Snow algae are found in snowfields across cold regions of the planet, forming highly visible red and green patches below and on the snow surface. In Antarctica, they contribute significantly to terrestrial net primary productivity due to the paucity of land plants, but our knowledge of these communities is limited. Here we provide the first description of the metabolic and species diversity of green and red snow algae communities from four locations in Ryder Bay , Antarctic Peninsula.During the 2015 austral summer season, we collected samples to measure the metabolic composition of snow algae communities and determined the species composition of these communities using metabarcoding.Chloromonas, Chlamydomonas and Chlorella were found in green blooms but only Chloromonas was detected in red blooms. Both communities also contained bacteria, protists and fungi.Green communities were protein‐rich, had a high chlorophyll content and contained many metabolites associated with nitrogen and amino acid metabolism. Red communities had a higher carotenoid content and contained more metabolites associated with carbohydrate and fatty acid metabolism. These data show the complexity and variation within snow algae communities in Antarctica and provide initial insights into the contribution they make to ecosystem functioning. Samples were returned within 3 h of sampling to the Bonner Laboratory , where they were melted in 4°C lit incubators . Algal cell density was measured by adding 6 μl of snowmelt into Hycor Kova haemocytometer wells and counting the number of algal cells using bright field microscopy. Algal community dry cell mass was obtained by gravity filtration of 50 ml of melted snow through a preweighed dry filter . Filters were dried at 80°C for at least 48 h before reweighing. Samples for FT‐IR analysis, which enabled measurements to be obtained as close as possible to the time of sampling ensuring minimal metabolic degradation, were processed by pelleting 2 ml of snowmelt (2000 g for 10 min at 4°C), discarding the supernatant and drying the pellet at 80°C for 24 h, followed by 24 h in a desiccator. The dried pellets were analysed on station using a Perkin‐Elmer Spectrum Two FT‐IR device, set to measure the absorbance intensity between wavenumbers 400 and 4000 cm−1 and normalised against air. For the metabolite and genomic analysis, carried out at the Department of Plant Sciences, Cambridge, 10 ml of snowmelt was pelleted using centrifugation , after which the supernatant was discarded and the remaining algal pellet was flash frozen in liquid nitrogen and stored at −80°C. Live algae were transported to the UK by adding 20 μl of snowmelt containing algae onto Tris‐acetate‐phosphate (TAP) agar slopes in 30 ml clear plastic tubes for growth under controlled conditions  at Cambridge and were imported under UK APHA/DEFRA licence number 119979/260872/0. The slopes and frozen samples were transferred to the UK by ship at 4°C or −80°C.Snow algae communities Fig.  were colg for 10 min). The supernatant was removed and the remaining pellet was homogenised with glass beads and frozen in liquid nitrogen three times, after which 1 ml of dimethylformamide was added and sonicated for 30 min. Samples were repelleted and the supernatant was transferred to an HPLC glass vial, mixed with methanol (3 : 2) and stored at −80°C until analysis. Pigments were separated by HPLC  as described by Remias & Lütz   with 1 ml dimethylformamide using the equations of Inskeep & Bloom  and Wells & Lütz  but usinet al. (Lipids were extracted using the chloroform/methanol/water method and triacylglycerides (TAGs), polar lipids and free fatty acids in the total lipid extract and total fatty acid methyl esters (FAMEs) were analysed by GC, as described in Davey et al. .et al. (N‐methyl‐N‐trimethylsilyl‐trifluoroacetamide (MSTFA) and trimethylsilyl (TMS) as described by Dunn et al.  with a ZB‐5MSi column . The injection volume was 1 μl (splitless) with an injector temperature of 300°C, using helium as a carrier gas (constant flow rate of 1.0 ml min−1). The following gradient was used: initial oven temperature 70°C; 130°C at 10°C min−1; 230°C at 5°C min−1; 310°C at 20°C min−1; hold for 5 min. The MS conditions in the positive mode were: transfer line 310°C; ion source, 310°C; mass range 45–800 Da; dwell time 0.17 amu s−1. GC‐MS spectra were aligned to an internal standard  and nist software (nist v.2.0 http://www.nist.gov/srd/nist1a.cfm) to aid identification based on molecular mass. Pathway analysis of the identified metabolites used metaboanalyst open source software  using the Arabidopsis thaliana metabolic pathway library . R script for the metaboanalyst software can be downloaded at https://github.com/xia-lab/MetaboAnalystR  of field‐collected algal communities from 10 ml snowmelt were allowed to thaw before being resuspended in 1 ml of RNase‐free water. After transferring to a clean 1.5 ml microfuge tube, the samples were ground with sterilised sand before adding another 1 ml of RNase‐free water and subsequent transfer to a 15 ml tube to which 3 ml of SDS‐EB buffer  was added, followed by mixing by vortexing and shaking for 5 min at 4°C. Subsequently, 3 ml of chloroform was added, mixed gently by inversion and the whole suspension was centrifuged for 5 min at 2000 g and 4°C, resulting in a two‐phase separation. The top aqueous phase was transferred to a new 15 ml tube and two volumes of 100% chilled ethanol were added before incubating overnight at −20°C. The following day, the mix was spun at 6800 g at 0°C for 30 min. After carefully discharging the supernatant, the pellet was resuspended with 1 ml of ethanol (70%) and recovered in a clean microfuge tube before determining total RNA concentration and quality. Libraries of the fourth hypervariable (V4) domain of the 16S rRNA gene and ITS of the rRNA gene were produced using the NEXTflex ‘16S V4’ and ‘18S ITS’ Amplicon‐Seq Library Prep Kit and primers , respectively. For consistency we hereafter use the term ‘ITS’ for the NEXTflex 18S ITS region. The microbial 16S rRNA gene forward primer (V4 Forward) sequence was: 5′‐GACGCTCTTCCGATCTTATGGTAATTGTGTGCCAGCMGCCGCGGTAA‐3′ and the reverse primer (V4 Reverse) sequence was: 5′‐TGTGCTCTTCCGATCTAGTCAGTCAGCCGGACTACHVGGGTWTCTAAT‐3′. The eukaryotic ITS forward primer (18S ITS Forward) sequence was: 5′‐CTCTTTCCCTACACGACGCTCTTCCGATCTTCCGTAGGTGAACCTGCGG‐3′ and the reverse primer (18S ITS Forward) was 5′‐ CTGGAGTTCAGACGTGTGCTCTTCCGATCTTCCTCCGCTTATTGATATGC‐3′. Samples were sequenced by Cambridge Genomic Services  using an Illumina MiSeq v3 600‐Cycle Sequencer following the manufacturer's protocol and primers. Quality control analysis of the Illumina MiSeq paired‐end reads (2 × 300 bp) was performed using fastqc (https://www.bioinformatics.babraham.ac.uk/projects/fastqc/). Taxonomic analysis of 16S rRNA gene sequences was performed using qiime 2 release 2017.10 . In brief, for each sample, demultiplexed paired‐end sequences were imported into qiime 2. Potential amplicon sequence errors were corrected with the qiime 2 implementation of dada2  marker gene reference database , the lowest common denominator was used for taxonomic assignment. Since there were so few operational taxonomic units (OTUs), and in the absence of an ITS database that is representative of the communities under investigation, we treated these results as exploratory. Sequence reads were submitted to the ENA Sequence Read Archive at the European Bioinformatics Institute (https://www.ebi.ac.uk/ena) and are available under accession number PRJEB23732.Frozen pellets (1−) and kasugamycin (50 μg ml−1). Cultures were maintained under a 12 : 12, light : dark photoperiod at 4°C. PCR mixtures contained REDTaq ReadyMix PCR Reaction Mix (Sigma) with 10 μM of the 18S rRNA gene universal eukaryotic primers , with expected product size of 582–584 bp. Primers were adapted from Wang et al.  and grown axenically on TAP agar plates supplemented with ampicillin  or two‐way ANOVA with Tukey's test  were performed. Multivariate analyses to test whether green and red communities could be discriminated based on their identified and unidentified metabolites (from FT‐IR fingerprints or GC‐MS profiling datasets) were performed using principal components analysis (PCA)  to produce standard score scatter plots and ranked score contribution plots of how each variable (FT‐IR wavenumber or GC‐MS metabolite) contributed to clustering within the PCA score scatter plot.To determine whether the differences between green and red communities, or among bloom site locations, were statistically significant, qiime 2's diversity analyses (q2‐diversity) plugin . In brief, the core‐metrics‐phylogenetic method was applied, which first subsamples the counts from each sample in order to obtain an even sampling depth (43 828 for the 16S rRNA data and 69 for the ITS data). Alpha and beta diversity metrics (Faith's Phylogenetic Diversity and Pielou's Evenness) were subsequently computed (PERMANOVA). To determine whether the richness of the samples had been fully captured, alpha diversity rarefaction plots were calculated using the qiime diversity alpha‐rarefaction visualiser. Plots for 16S rRNA gene and ITS data approached saturation at depths of 43 828 and 69 sequences, respectively  with stress levels of 0.1–0.2, using the Bray–Curtis dissimilarity calculation  varied (1–30) per site, and these sample numbers are given in the figure and table legends.Alpha diversity and beta diversity were measured using ly Fig. , suggest6 cells per ml snowmelt (± 0.17 × 106) vs 1.24 × 106 cells per ml snowmelt (± 0.79 × 106), respectively , with, on average across all sites, 62% less biomass in the red‐dominated communities than in the green communities  in cell numbers or cell dry masses between sampling locations in the red communities. However, the green communities on Léonie Island had a greater number of cells (c. 2.2 × 106 more cells per ml) and biomass (c. 2.9 g dry mass more per litre) of snowmelt than on the other islands .There were many fewer cells in the red algal communities than in the green communities, with mean (± SD) cell densities of 0.15 × 10ly Fig. a. Similaes Fig. b. There −1) or red  snow algae communities  and per volume snowmelt (c. 90% more) , which was probably due to the greater biomass per unit of snowmelt at that location. There were no other effects of location on total Chl or total carotenoid in the red communities.Crude solvent extractions and ultraviolet–visible spectrometry of green and red blooms shortly after field collection showed the presence of peaks indicative of Chlin Fig. . There we) Fig. a,b. Ther Fig.  c or on aa and b, β‐carotene and lutein, and in the red community were Chla and b and astaxanthin esters. The main differences between the communities were that the red communities had significantly less Chla and b, β‐carotene, lutein  and xanthophyll and more astaxanthin‐like and astaxanthin esters, although these were not significant (Table a to Chlb was similar in both green (1.9 : 1) and red (2.2 : 1) communities.Pigment composition was analysed in detail using HPLC. As there was minimal effect of location from the above pigment analyses, samples from the islands were pooled to provide an average composition over Ryder Bay for green and red communities Table . Dominant Table . The ratP ≤ 0.05) more neutral storage lipids (TAGs) per unit dry mass in the lipid extracts from the red community at Lagoon Island . Unlike the other metabolites detected, there was little variation in the nonpolar (TAG) and polar lipid content between the green and red communities, nor between the different island locations. The exception to this was significantly  fatty acids Table . Overallin silico MetaboAnalyst Pathway Analysis Tool. Metabolites involved in energy production and the TCA cycle and in nitrogen and amino acid metabolism, such as succinic acid and the amino acids asparagine and valine, were strongly associated with green snow algae communities   on unweighted UniFrac distances generated during the first diversity analysis step was used to test whether sequence reads from samples within a bloom type were more similar to each other than they were to samples from the other bloom type. Similar to alpha diversity, there was no significant dissimilarity between the green and red 16S rRNA gene and ITS communities (P ≥ 0.05) . To test for associations between discrete metadata categories  and alpha diversity data, the community richness and evenness were calculated using Faith's Phylogenetic Diversity  and Pielou's Evenness (a measure of community evenness). No significant differences in community richness or evenness were measured between green and red 16S rRNA gene and ITS sequence‐based communities (t) Fig. . For bett) Fig.  test (us5) Fig. . Beta di Fig.  . Chloromonas, Chlamydomonas and Chlorella were detected in approximately equal measures, whereas in the red blooms only Chloromonas was identified, with the other OTUs being assigned to unknown Chlorophytes  and grown axenically, during which the cells transformed from their red phase to a green phase (over 21 d). A blast search of the forward and reverse nucleotide sequences resulted in 98–99% similarity to Chloromonas sp. and Chlamydomonas sp., supporting our initial classification. However, a blast search against only Chlamydomonas nivalis or Chloromonas nivalis sequences resulted in just 92% similarity . The number of Sphingobacteria OTUs was statistically significantly lower (P < 0.05) and Chryseobacterium reads significantly higher (P < 0.01) in the red communities compared to the green communities , which is reported to catabolise it , a yeast in the genus Cryptococcus (Tremellaceae) and chytrids in the Rhizophydiales (Fungi) , determined species matching our metabarcoding OTUs for the red blooms (Chloromonas), implying that this taxon may be distributed widely, at least along the Antarctic Peninsula. In a similar study in continental Antarctica , Fujii et al.  and, as here, a range of yeasts. Although the detailed composition of bacterial, protist and fungal communities in snow algal blooms may be different across the globe, it is becoming apparent that snow algae communities have similar wide functional and taxonomic structures. The dominance of fungi, specifically yeasts and chytrids, in the communities studied here is of particular note, with fungi also having been identified as important components of Arctic snow packs  and North America (Hoham gi) Fig. . The Rhi, et al. , studyini et al.  also ideo et al. ) and numMPD, KKN, PC and LSP designed and planned the fieldwork and logistics. MPD carried out the fieldwork. MPD, LN and AGS planned the field sample analysis at Rothera and Cambridge with MPD and LN extracting and analysing the metabolites at Cambridge. MH‐O performed the DNA extraction for metabarcoding and PS performed the metabarcoding bioinformatics. FB and BKWL carried out the algae isolation and targeted 18S analysis. MPD and SS carried out the pigment analysis. MPD led the writing of the manuscript with all other authors contributing and editing the text. All authors have seen and approved the final version.New Phytologist Central Office.Please note: Wiley Blackwell are not responsible for the content or functionality of any Supporting Information supplied by the authors. Any queries  should be directed to the Fig. S1 Alpha diversity rarefaction plots.Fig. S2 Snow algae community biomass and cell counts.Fig. S3 Representative ultraviolet–visible absorption spectra of solvent ethanol extracts from green‐ or red‐dominant snow algae communities.Fig. S4 Pigment content of snow algae blooms.Fig. S5 Alpha diversity boxplots.Fig. S6 Screen shots of beta diversity boxplots.Fig. S7 Metabarcoding NMDS plots.Fig. S8 Composition of Chlorophyta OTUs in green and red snow algae blooms.Methods S1 Raw read metabarcoding R script files in vegan.Table S1 Sampling locations and light (PAR) and temperatures recorded at snow surface and 5 cm depth during sampling.Table S2 FT‐IR metabolic fingerprinting of snow algae communities.Table S3 Fatty acid composition of snow algae.Table S4 Score contribution of putatively identified metabolites associated with either green or red snow algae communities.Table S5 Metabolite pathways of the putatively identified metabolites associated with either green or red snow algae communities.Table S6 Percentage contributions and number of taxonomic assignments for Level 2 (Kingdom/Phylum) 16S rRNA gene and ITS sequences in green and red snow algae communities.Table S7 Percentage contributions and number of taxonomic assignments for Level 3  16S rRNA gene and ITS sequences in green and red snow algae communities.Table S8 Percentage contributions and numbers of taxonomic assignments for Level 6  16S rRNA gene and ITS sequences in green and red snow algae communities.Table S9 Targeted genomic identification of snow algae.Click here for additional data file.


Patients with higher A/L ratios had worse survival than those with lower A/L ratios . Further, in multivariate analysis, serum A/L ratio was a significant prognostic factor in patients with AE-IPF . In conclusion, the higher adiponectin/leptin ratio may be associated with a poor prognosis in patients with AE-IPF.Weight loss progresses with the progression of idiopathic pulmonary fibrosis (IPF), and acute exacerbation of IPF (AE-IPF) frequently occurs in its advanced stage. Adiponectin and leptin are adipokines produced from adipose tissue, and are related to thinness and obesity, respectively. Additionally, these adipokines are implicated in the regulation of inflammation and fibrosis centering on peroxisome proliferator-activated receptor γ (PPARγ). However, the relationship between adiponectin/leptin and AE-IPF remains poorly known. We conducted this study to evaluate levels of serum adiponectin/leptin, and to elucidate the clinical importance of adiponectin and leptin in patients with AE-IPF. Thirty-two patients (39 episodes) who were diagnosed with AE-IPF at our hospital from 1997 to 2016 were retrospectively studied. Serum adiponectin and leptin concentrations were measured with enzyme-linked immunosorbent assay. Patients with AE-IPF showed higher levels of serum adiponectin and leptin than those at initial diagnosis of IPF . Serum adiponectin/leptin (A/L) ratio was negatively correlated with body mass index at AE-IPF  and PaO AE occurs more frequently in patients with IPF than in those with other interstitial pneumonias such as connective tissue disease-associated interstitial pneumonia4, and causes 30–40% of all deaths6. In patients with IPF, AE more often occurs in the advanced stage of IPF than in its early stages7. Patients with IPF lose further weight as the disease progresses. Therefore, the amount of adipose tissue should decrease in the advanced stage of IPF.Idiopathic pulmonary fibrosis (IPF) shows a catastrophic prognosis9. Additionally, the regulation of inflammation centering on the transcription factor peroxisome proliferator-activated receptor γ (PPARγ) has been reported in the biology of these adipokines9. Adiponectin and leptin have the opposite effect on PPARγ expression: adiponectin increases the level of PPARγ and leptin conversely decreases it8. Regarding fibrosis, decreased adiponectin levels were recently reported in patients with systemic sclerosis and interstitial pneumonia11. Furthermore, leptin levels in bronchoalveolar lavage fluid reportedly increased in patients with acute respiratory distress syndrome (ARDS), and higher leptin levels were associated with higher mortality in nonobese patients12. In addition, Cao et al. reported that plasma leptin levels increased at AE-IPF, and AE-IPF patients with higher leptin levels at AE showed worse prognosis than those with lower levels13. These results lead us to hypothesize that not only leptin but also adiponectin, which have opposite effects on PPARγ expression, may be related to pathogenesis of AE-IPF in the advanced stage of IPF. Further, adiponectin levels in patients with AE-IPF and their mechanism of action have been unknown.Adiponectin and leptin are adipokines produced from adipose tissue and are related to obesity and emaciation. These adipokines have pleiotropic functions, and affect lymphocytes, macrophages, epithelial cells, endothelial cells, and smooth muscle cellsIn the current study, we retrospectively studied patients with AE-IPF and evaluated serum concentrations of these adipokines. To the best of our knowledge, this is the first study to show the relationship between these two adipokines, and the relationship between adipokines and clinical parameters/prognosis in patients with AE-IPF.CO) within 12 months before AE-IPF onset was moderately impaired . The most frequent IPF severity grades were GAP III (36%), and Japanese Respiratory Society (JRS) grade IV (36%), which is the most severe grade in each grading system. Twenty-four of 39 patients (62%) underwent treatment for IPF before AE-IPF, including corticosteroids, immunosuppressants, and pirfenidone. Thirteen patients (33%) underwent long-term oxygen therapy before AE-IPF. At the diagnosis of AE-IPF, the median number of peripheral blood white blood cells was 9755/μL and the median PaO2/FiO2 (P/F) ratio was 176. Steroid pulse therapy was administered to all patients. Treatments for AE-IPF began as soon as possible after admission concomitantly with antibiotics administration. The period from admission to beginning treatments for AE showed a median of one day.Clinical characteristics of all patients (39 episodes) are shown in Table Serum adiponectin and leptin levels were evaluated in 39 episodes of AE-IPF, for which serum was available at the diagnosis of AE-IPF Fig. . Median 8. A negative correlation was found between A/L ratio and BMI  ratio  at AE-IPF in 39 patients, the patients were divided into two groups. For the prognostic analysis, comparisons of clinical data between patients with higher A/L ratio (≥905) and lower A/L ratio (<905) in 32 patients without duplicate are shown in Supplementary Table Among 32 patients with AE-IPF, seven died within 1 month of onset , 9 died within 3 months , and 23 died within 12 months  from the first episode of AE-IPF. Nineteen patients died of respiratory failure and four died of infectious pneumonia after beginning of steroid-treatment. Kaplan-Meier survival curves from the first AE-IPF onset are shown in Fig. 2 before AE-IPF, and positively correlated with CRP. Finally, A/L ratio was a significant prognostic factor in patients with AE-IPF. To the best of our knowledge, this is the first study to show the relationship between adiponectin and leptin, and the significance of these two adipokines in patients with AE-IPF.In this study, we evaluated serum adipokine concentrations and determined whether adipokines were important to predict prognosis in patients with AE-IPF. Patients with AE-IPF had increased levels of serum adiponectin and leptin compared with those at first diagnosis of IPF. A/L ratio negatively correlated with BMI and PaO9. In patients with obesity and type II diabetes mellitus, the serum adiponectin level decreases and that of leptin increases9. Conversely, in emaciated subjects, adiponectin increases and leptin decreases. Furthermore, the biological functions of both adipokines are closely linked to PPARγ activity and its anti-inflammation capacity9. In the current study, however, both adiponectin and leptin levels increased at AE-IPF, and the mechanism of action of these adipokines does not seem to be simple like in obesity or diabetes mellitus.Adiponectin and leptin are produced from adipose tissue, and these adipokines are related to obesity and type II diabetes mellitus9. Leptin reportedly promotes profibrotic gene transcription related to transforming growth factor (TGF) β in patients with ARDS without obesity12. Further, Cao et al. reported that leptin levels increased at AE-IPF, and AE-IPF patients with higher leptin levels at AE had poorer prognosis than those with lower levels13. Even in the present study, the leptin level significantly increased at AE-IPF. However, higher leptin alone was not related to worse prognosis, and higher adiponectin rather seemed to be related to poor prognosis. Adiponectin has anti-inflammatory effects via activation of PPARγ9. Furthermore, adiponectin suppresses TGF β signaling centering on PPARγ8, and suppresses acute lung injury14. Reportedly, in patients with IPF15 or systemic sclerosis11, adiponectin levels significantly decreased. Conversely, several studies have shown that adiponectin has profibrotic effects. Higher adiponectin levels were positively related to advanced liver fibrosis in hepatitis B viral infection17, and lack of adiponectin was associated with dampened wound healing in diabetes mellitus18. Further, adiponectin promoted collagen production from fibroblast20, induced intercellular adhesion molecule (ICAM)-1 on fibroblast21, and then facilitated its adhesion capacity20. In the current study, both adipokines increased at AE-IPF, and higher A/L ratio was rather related to poorer prognosis. Although the exact mechanism related to these adipokines remains unknown in AE-IPF, these results imply that adiponectin’s anti-inflammatory (profibrotic) effects following leptin’s proinflammatory effects may play a role in the pathogenesis of AE-IPF. This pathogenesis seems to be similar to the activation of M2 (anti-inflammatory and profibrotic) alveolar macrophages following that of M1 (proinflammatory) macrophages in acute lung injury or ARDS22.Leptin has proinflammatory effects via PPARγ suppressionThis study has several limitations. First, only a small number of patients with AE-IPF were enrolled. Second, the clinical and prognostic data were retrospectively analyzed. Finally, the treatment of AE-IPF was not uniform. A prospective and larger study should be conducted to determine the role of adipokines in patients with AE-IPF.In conclusion, this study showed that serum adiponectin and leptin levels significantly increased in patients with AE-IPF. A/L ratio positively correlated with CRP, and A/L ratio was a significant prognostic factor in patients with AE-IPF. These adipokines are closely associated with the balance between inflammation and fibrosis, and may play a role in the pathogenesis of AE-IPF. A larger and prospective study is needed to precisely evaluate the role of these adipokines in the pathogenesis of AE-IPF.1. The remaining 12 patients showed clinical and high-resolution computed tomography (HRCT) features identical to IPF and were diagnosed with IPF without surgical lung biopsy1. Patients diagnosed with any connective tissue disorders were excluded from the study.Thirty-two patients who were diagnosed with AE-IPF at our hospital between 1997 and 2016 were studied. Seven patients had two episodes of AE-IPF , and this study was carried out in accordance with the approved protocol. The need for patient approval and informed consent was waived due to the retrospective nature of the study.AE-IPF was diagnosed according to the modified diagnostic criteria as previously described28 and the Japanese Respiratory Society (JRS)-severity scale of interstitial pneumonia7. The former considers gender, age, and two lung physiology variables: FVC and DLCO28. The latter is based on PaO2 at rest and minimum SpO2 during the 6-minute walking test (6MWT)7.Clinical data were obtained from the medical records. Disease severity of IPF within 12 months before the AE event was assessed using the GAP-staging system30. The sum of the scores from five lobes (0–25) was used to express the extent of lung opacities in each patient. The HRCT patterns of AE-IPF were evaluated as reported by Akira31. The HRCT findings were reviewed by two observers.The extent of lung opacities was measured on three HRCT slices as previously describedAll blood samples were collected on the first or second day of admission before starting treatments for AE-IPF. Serum adiponectin and leptin concentrations were measured with enzyme-linked immunosorbent assay .t-test. Continuous data at different time points in the same patient were compared using the paired t-test. The relationship between adiponectin/leptin ratio and serial data was analyzed using Pearson’s correlation coefficient, and that between adiponectin/leptin ratio and discrete variable data was analyzed using Spearman’s rank correlation coefficient. Survival of patient groups was evaluated with Kaplan-Meier curves, and was compared between groups using the log-rank test. The relationships between variables and mortality were assessed by the Cox proportional hazards regression analysis. All tests were two-sided and statistical significance was set at p < 0.05.Statistical analyses were performed using StatView J-4.5 and JMP-13.1.0 . Categorical data were compared using the Chi-square test or Fisher’s exact probability test for independence, and continuous data were compared using the unpaired Supplementary Information


We present an effective scheme to improve the modulation capacity in graphene-based silicon modulator by employing the double slots configuration with hybrid plasmonic effects. Two modulators, i.e., metal-insulator-metal and insulator-metal-insulator configurations have been demonstrated, showing that the double slots design can significantly improve the modulation efficiency. The obtained modulation efficiency is up to 0.525 dB/μm per graphene layer, far exceeding previous studies. It can be found that the light-graphene interaction plays a pivotal role in the modulation efficiency, whereas the height of metal has profound influence on the modulation. Our results may promote various future modulation devices based on graphene. Among these devices, graphene-based optical modulators dictates sharply contrasting properties: the modulation speed, the bandwidth, and especially the efficiency can be improved by orders of magnitude, compared with silicon modulators2. In 2011, modulator composed of single-layer graphene on top of silicon waveguide was experimentally studied3, with an operation speed of 1.2 GHz, a broad optical bandwidth (1.35–1.6 μm), and a modulation efficiency (ME) of 0.1 dB/μm. In 2012, a modulator with two graphene layers was proposed4, working with improved modulation efficiency at 0.16 dB/μm. Further improvement has been demonstrated in a similar two-layer graphene based modulator in year 2013, with an improved modulation efficiency of 0.34 dB/μm5. A ultra-compact graphene-embedded silicon waveguide modulator was investigated with a high ME over 0.3 dB/μm6. In all these designs, the most difficult part is that the thickness of graphene is only 0.34 nm, but the corresponding optical wavelength in silicon is around hundreds of nanometers. Thus, there is a strong dimension mismatch between graphene and silicon, which indicates that graphene can only capture very few portions of the optical mode in these designs. Such drawback seriously limited the ME, e. g., the ME is only 0.1 dB/μm in ref.3. One possible solution we proposed before is to use the hybrid plasmonic effect in the slot waveguide to squeeze the optical field and enhance its integration with graphene7. However, in such design, the large portion of the mode leaks in the background. The potential of combining the versatility of graphene with subwavelength field confinement of plasmonic waveguides still need to be improved.Graphene optics, in tandem with silicon devices, have received much attention in the past two decadesIn this paper, we design novel modulators based on double-slots plasmonic waveguide (DSPW) with enhanced light-graphene interaction. Our results show that the ME in the designed DSPW modulators can be significantly improved than all previous results.According to different symmetries, two kinds of DSPWs have been proposed, i.e., the insulator-metal-insulator (IMI) configuration and the metal-insulator-metal (MIM) configurationnAg = 0.1453 + 11.3587i) rib waveguide (WAg = 300 nm) is sandwiched between two silicon blocks  to form a compound hybrid plasmonic waveguide  on the surface of a SiO2 substrate (nSiO2 = 1.45). In this design, the double-layer graphene isolated by 10 nm Al2O3 layer  can be set as “Off”, and low propagation loss (μ = 0.55 eV) can be set as “On” for a modulation.The IMI configuration is illustrated in Fig. 9, there are two coupled modes in a pair of silicon waveguide named the odd symmetrical mode and the even symmetrical mode. In Fig. Ex fields at the two sides are opposite. In Fig. Ex field distribution where the signs of Ex fields at the two sides are the same. This also can be found from the arrows in Fig. In Fig. 10, ME is used here to estimate the potential modulation capacity. ME is defined as the modulation depth  per micro-meter. Figure WSi increases from 180 to 340 nm. Here, EIF is defined in the signal 0 state to quantitively study the graphene-light interaction:11. EIF represents the degree of the light concentration in graphene, and the more the optical field concentrates in graphene, the more modulation capacity can be obtained. In Fig. WSi continuously increases. The even mode of IMI-DSPW has the highest ME for all the WSi values because it has the strongest confinement. On the other hand, the odd mode of IMI-DSPW has the worst ME performance, because the odd mode of IMI has the smallest field concentrated in graphene according to smaller EIF as shown in Fig. In accordance with previous studiesentclass1pt{minimaWGap = 30 nm) are inserted between the silicon rib  and the two Ag waveguides (WAg = 300 nm). Two graphene layers are embedded in the compound waveguide with an isolated 10 nm Al2O3 layer. Figure Ex field distribution for the designed MIM configuration. Unlike previous IMI case, the leaking modes gathering at the two sidewalls disappear, and all the intrinsic modes are concentrated in the central region, most of which are filled inside the slot areas. This indicates a much stronger EIF in the MIM structure than in the IMI structure, thus a larger ME shall be expected in the MIM structure.In Fig. WSi. As a comparison, the ME for single slot waveguide is also plotted. The MIM configuration significantly improves ME with the maximum ME up to 0.82 dB/um, which is not only larger than the single slot waveguide but also larger than the largest ME value for the IMI-DSPW in Fig. WSi from 200 nm to 340 nm, the ME for MIM-DSPW gradually decreases, because the increased central silicon region leads to a weaker light confinement. For the MIM configuration, it can be found that the ME/EIF is inversely proportional to the slot width, as can be seen in Fig. WGap has the largest ME. In Fig. Figure 13, the surface plasmon is localized and significantly enhanced at the sharp corners of metal. Therefore, the idea here is to introduce the sharp corners of the metal inside the double-slots region. We deliberately reduce the height of the Ag region of the DSPW, as depicted in Fig. According to previous plasmonic knowledgeHAg and width of the silicon waveguide Wsi. Since Ag is separated into two parts by the insertion of the graphene layer, only the top part of HAg is modified while the bottom part keeps constant at 105 nm. Our results show HAg has dominate influence on ME: the decrease of HAg significantly enlarges ME in Fig. HAg not only introduces sharp metallic corners in the slot region, which enhances the hybrid plasmonic effects, but also enlarge the EIF factor according to Eq. , as shown in Table There are plenty of designs on the topic of graphene-based modulators including single-layer graphene12 have shown the feasibility of experimental verification of graphene-based plasmonic modulators.In this paper, the double slots configuration has further improved the ME per layer. The ME per layer for even mode of IMI-DSPW has improved to 0.486 dB/μm, and for MIM-DSPW, it has improved to 0.525 dB/μm. To our knowledge, this is also the largest ME per graphene layer ever reported. This paper mainly focuses on the theoretical investigation and the optimization of the modulator performances. Although the fabrications of the proposed sandwich structures are quite challenged for the present clean room technology, the previous literatureIn conclusion, we propose a novel IMI-DSPW and MIM-DSPW modulator to significantly improve the modulation capacity. The modulation efficiency of the proposed MIM-DSPW is over ~0.525 dB/μm per graphene layer. The ME and corresponding EIF under different DSPW approaches and geometrical parameters are also investigated. It is found that the EIF is of great importance to the ME, and the height of metal also dramatically influences the modulation efficiency. Our results may benefit the design of high-performance on-chip electro-optical modulator.7, and e, T, ω is the angular frequency, Γ is the scattering rate, and μ is the chemical potential of graphene.Graphene is an anisotropic material, its permittivity in the out-of-plane direction The EM wave simulation in this paper is based on mode analysis on the cross-section of the waveguide. The principle is to use the intrinsic mode distribution to analyze the wave vector (propagation constant) of the waveguide, as a result, the real part of the propagation constant indicates the phase performance, and the imaginary part epotomizes the loss information. The eigenvalue solver of commercial software COMSOL was used to find modes of the hybrid waveguide. The effective index and propagation distance were determined from the real and imaginary parts of the eigenvalue. The extremities of the calculation region were given scattering properties to mimic the necessary open boundary conditions. A convergence analysis was conducted to ensure that the real and imaginary parts of the effective indices varied within 1%.


The mechanical response (deflection) of the bimaterial (the coated cantilever) was investigated under the influence of relative humidity. The variations in the deflection of the coated cantilevers when exposed to relative humidity were evaluated. The results indicated a linear sensitivity in ranges, where the high value was obtained for a polypyrrole-sensitive layer between 20 and 45% of humidity. Furthermore, the sensor shows excellent performance along with rapid response and recovery times, relatively low hysteresis, and excellent stability. The sensors developed are potentially excellent materials for sensing low humidity for long time.This paper describes the use of different conducting polymers (polyaniline, poly( Highly sensitive sensors capable of rapid, real-time, in situ biological and chemical detection are desired. Thus, the sensors based on cantilevers present as miniaturized devices, extremely sensitive to several environmental factors , humiditIn this context, there has been a considerable interest in exploring the conducting polymer as a sensitive layer in humidity sensors. Conductive polymers are organic materials having such a structural feature of the combination of monomeric units and can undergo reduction and oxidation reactions. Also, characterized by having electrical properties and magnetic and optical typical metallic behavior but with mechanical properties and processability solution commonly associated with conventional polymers , 5.o-ethoxyaniline) [Conducting polymers suffer many changes when exposed to an analyte, such as modifications of the backbone conformation, solvation effects on the polymer chain, and the attraction of dopant counter ions or transfer of electrons . Thus, caniline) –13, polyaniline) , and polaniline) .Lahav et al.  used an Steffens et al.  evaluatev and response time less than 2.1 seconds.Steffens et al.  evaluateo-ethoxyaniline), and polypyrrole. The technique employed to deposit the polymeric films on the substrates is the spin-coating technique. The linear sensitivity, response time, detection limit, and reversibility of the cantilever sensors were evaluated.In this research was study functionalization of silicon cantilever with different conducting polymer layers, aiming the development of humidity sensors. The polymers studied include polyaniline, poly kHz, spring constant of 0.03–0.13 N/m, and dimensions (rectangular shape) of 350.0 o-ethoxyaniline) was obtained by chemical synthesis as described by Mattoso et al. [The poly and washed with methanol and Milli-Q water.The polyaniline was obtained in the emeraldine base oxidation state by an interfacial synthesis followed by a chemical route to obtain the polyaniline nanofibers as reported by Huang and Kaner . The aniCommercial polypyrrole (Aldrich) was used, and its pH was adjusted to 2 with 1 M HCl. All reagents used had analytical grade P.A. and were used without any further purification.o-ethoxyaniline), the polymers synthetized were dissolved in 5 mL of N-methyl pyrrolidone; these solutions are kept in an ultrasound (Branson) for 30 min for solubilization.In order to obtain the solution of polyaniline and poly(o-ethoxyaniline), and polypyrrole), all doped with HCl, and thin filmed by the spin-coating method, as reported previously by Steffens et al. [The AFM cantilever was functionalized with different polymers , through monitoring the position of the laser beam, which is focused at the endpoint of the cantilever and reflected to a four-quadrant photodiode, and this signal value was converted in nanometers. All measurements of deflection were performed in triplicate at a static mode of operation.The cantilever sensor deflection was measured at various relative humidities (RH) in a closed chamber (9 mL) in the static mode. The humidity in the chamber was obtained by combining flows of dry nitrogen (RH from 70 to 20%) and wet nitrogen passing by gas bubbler tube containing water (RH from 20 to 70%) at a flow rate of 0.1 L/min . The temperature in the chamber during the experiments was maintained constant at 20 ± 0.2°C using an ultrathermostatic bath .η) of the cantilever sensors at different humidities was calculated as follows [D0 is the initial deflection of the microcantilever sensor obtained at 20% of humidity, D is the deflection after exposure to a flow of dry nitrogen, and Df is the minimum deflection after exposure to wet nitrogen using a water bubbler. The initial deflection of the cantilever sensors was 10 nm during the three cycles evaluated. The reversibility was calculated to assess whether the ability of the sensors varies its state of deflection under the action of humidity and returns to its initial state when the humidity left to act on the sensitive coating. The linear sensitivity of the cantilever sensor was calculated from the slope of the deflection (nm) versus humidity (20–70%) curve.The reversibility The sensor hysteresis was calculated as the difference between the mean measured values during the drying and wetting stages.Detection limits was calculated as the lowest concentration of humidity giving a signal of three times the medium-term deflection stability of the sensor according to the International Union of Pure and Applied Chemistry (IUPAC).The reversibility and detection limit of the cantilever sensors were expressed as means ± standard deviation and subjected to one-way analysis of variance (Tukey) test at 5% significance using Statistic 5.0  software.o-ethoxyaniline), then decreased upon return to wet gas. The sensor responses to humidity were completely reversible to all cycles evaluated (The deflection response (nm) of the cantilever sensors was evaluated varying the humidity over a large range  during desiccation and humidification cycles (wet and dried gas). valuated , also exIn v. The results demonstrated that the cantilever sensor functionalized with polypyrrole presented the higher reversibility and detection limit to humidity (p < 0.05) to other sensors. The polypyrrole film conduction is of p-type, thus, molecules of water act as electron acceptors attracting the polymer electrons, increasing the conductivity [The detection limit of sensors with different conducting polymers is as low as 170 ppbhumidity , differ uctivity . Also, suctivity .Yang et al.  evaluateSteffens et al.  observedThe results obtained in the concentration range from 20 to 70% of RH of cantilever sensors with different conducting polymers were shown in o-ethoxyaniline), and polypyrrole displayed a response time of 5, 10, and 4 s, respectively. It can be seen that the sensors functionalized with poly(o-ethoxyaniline) showed the slower response to RH. This is an indication that this polymer showed a great adsorption and desorption of water vapor molecules. Moreover, this shows a fast response time compared with resistive sensors which mostly range from 10 to 30 s at RH [The response time of the cantilever sensors coated with different conducting polymers was obtained when the sensor has reached a steady state from the time where the RH changed. The experiments were carried out to obtain a baseline and sequentially the insertion of wet gas in the chamber; the RH ranges from 20 to 50% at 20°C . The can s at RH . The res s at RH , and low s at RH .Geng et al.  evaluateThe humidity hysteresis was analyzed only for the cantilever sensor functionalized with polypyrrole. The humidity was decreased from 70 to 20% (by introducing dry nitrogen into a chamber) and increased from 20 to 70% (wetting nitrogen by passing through water at the same rate of 0.1 L/min) . The hyso-ethoxyaniline)) present many advantages in comparison to metal oxide and other humidity sensors due to their capacity to operate at room temperature at low cost.Thus, it is possible to observe that conducting polymers used  sensors to RH. The hysteresis of the sensor was found as 1.23% RH, and the response time measurements showed 3 seconds. The sensors developed are potentially excellent materials for sensing low humidity for long time.Different conducting polymers were applied to develop a humidity sensor using a microeletromechanical system (cantilever). The polypyrrole cantilever sensor presented very low detection limit and good reproducibility compared to polyaniline and poly(


Climate change has far-reaching effects on human and ecological systems, requiring collaboration across sectors and disciplines to determine effective responses. To inform regional responses to climate change, decision-makers need credible and relevant information representing a wide swath of knowledge and perspectives. The southeastern U. S. State of Georgia is a valuable focal area for study because it contains multiple ecological zones that vary greatly in land use and economic activities, and it is vulnerable to diverse climate change impacts. We identified 40 important research questions that, if answered, could lay the groundwork for effective, science-based climate action in Georgia. Top research priorities were identified through a broad solicitation of candidate research questions (180 were received). A group of experts across sectors and disciplines gathered for a workshop to categorize, prioritize, and filter the candidate questions, identify missing topics, and rewrite questions. Participants then collectively chose the 40 most important questions. This cross-sectoral effort ensured the inclusion of a diversity of topics and questions  likely to be important to Georgia policy-makers, practitioners, and scientists. Several cross-cutting themes emerged, including the need for long-term data collection and consideration of at-risk Georgia citizens and communities. Workshop participants defined effective responses as those that take economic cost, environmental impacts, and social justice into consideration. Our research highlights the importance of collaborators across disciplines and sectors, and discussing challenges and opportunities that will require transdisciplinary solutions. Climate change alters atmospheric chemistry and temperature, ocean chemistry and temperature, the frequency and intensity of extreme weather events, and precipitation patterns, all of which will directly and indirectly influence ecological systems and human well-being globally IPCC . PatternSociety’s response to climate change is shaped by economic, social, ecological, and political factors , a network of colleges and universities working with federal, state and local government officials, non-governmental organizations, private industry, and other partners seeking to improve understanding of climate impacts and solutions in Georgia.Effectively responding to climate change will require cross-sectoral and cross-disciplinary perspectives both to develop effective technical and policy responses and to understand how such responses may lead to synergistic or antagonistic outcomes across regions and sectors  brought a group of experts together to discuss and vet the submitted candidate research questions. Attendees included steering committee members, invited workshop participants not previously involved in project design or implementation, and student assistants. In an effort to ensure that a wide diversity of research priorities were addressed, we strategically invited workshop participants to balance, to the best of our ability, sectoral, regional, disciplinary, and demographic characteristics across a group of approximately 40 participants. The workshop participants (co-authors on this paper) represented a broad distribution of interests, expertise, sectors, career stages, and geographic locations (supplementary information Table S1), helping to ensure that a diverse range of candidate questions and that other important questions not represented in the candidate question pool were considered.The workshop followed the standard format . The final selection of key climate research questions important for policy- and decision-makers, practitioners, and scientists in Georgia is presented below grouped by theme. Each theme contains questions regarding both the effects of climate change in Georgia and potential responses. It is important to note that many of these questions cut across topical areas. Georgia’s 40 important research questions are not presented in rank order; a follow-up survey project , the vulnerability or sensitivity of people, infrastructure and ecosystems exposed to those hazards, and their resilience  emissions warming the planet. However, the National Academies of Sciences, Engineering, and Medicine  recently7.What species and ecosystems are most at risk of population declines or extirpation due to climate stresses?Species distribution models have been used to predict climate-driven habitat shifts for a variety of taxa , but such methods may vary greatly in cost and levels of acceptability for various management agencies, stakeholders, and citizens. Information about the trade-offs that groups are willing to make in terms of costs and management outcomes is needed to help evaluate the appropriateness of different management options  but research is needed to identify how other cities and municipalities can use nature to not just efficiently increase resilience to various stressors. Coastal protection is another example where the effectiveness and value of coastal protection has been assessed for other regions  include research and tools on irrigation, animal agriculture, and forestry. There is considerable scope however for improving these technologies, adapting them for Georgia conditions, developing new tools, and/or or introducing them to growers not familiar with them. This implies the need for more explicit and participatory engagement strategies along food supply chains and methods that directly incorporate input from farmers and extension agents, to take into consideration Georgia farmers’ explicit interests, needs and ideas  thus indirectly spreading vector-borne diseases  of many climate-sensitive environmental health exposures . These exposures, individually or in combination, will impact a range of health outcomes through direct and indirect pathways  and the healthcare sector  will be critical in responding to the health impacts of climate change. Enhancing the existing capacity to respond to climate-related health events and building the resilience of communities to avoid negative health impacts could play a major role in protecting at-risk citizens and communities. Adaptation and interventions exist to protect at-risk communities , directly influence the levels and concentrations of GHG emissions  across Georgia’s important climate research questions.39.What are the most cost-effective and equitable policy and technology options for reducing emissions of greenhouse gases in Georgia, and how can these be prioritized?www.rggi.org) in the northeast USA, for example, agreed in August 2017 to reduce GHG emissions by 30% across 9 States by 2030. Common approaches for assessing and presenting emissions reduction options include marginal abatement cost curves and stabilization wedges  incentives, policies and regulations, and operating at multiple scales presents a challenge to policy analysts. In Georgia, it would be useful to assess which interventions or investments are most effective at which scales  and identify policy pathways that are effective and adaptive, retaining flexibility to respond to changing conditions in the future. The simultaneous growth of adaptation and mitigation legal regimes may facilitate a reasoned and effective response to climate change. Legal solutions can help ensure that local, state, and federal governments, regional compacts, organizations, and individuals both limit climate change (through mitigation) and better respond to present and future climate risks (through adaptation) when making decisions about the built and natural environment. Existing laws could be modified or new laws crafted to deal with climate change  and susceptibility to damages. Efforts to addressing environmental injustices must consider who is most adversely impacted by environmental hazards and how their response is shaped by the various resources that different groups have access to  whether or not the questions adequately reflect the priorities of a broad set of stakeholders and (b) whether or not the answers to these questions will be relevant to policymakers and practitioners. We will seek to address both issues in our follow-up work, described below. With regard to the former, there is always the potential for the final list of important questions to reflect the personal perspectives of workshop participants rather than of the stakeholder community as a whole. However, the methodology outlined by Sutherland et al. , and whiAnother important consideration for the GCRR project in particular is whether or not it is generalizable beyond Georgia. The process itself is certainly transferable; it would be straightforward to apply exactly the same methodology to conduct a similar exercise in another state, for example. With regard to the questions themselves, it is difficult to speculate about their transferability to other locations. With a few exceptions , most of these questions could certainly be applied to other states. What is less clear, however, is how much priority key stakeholders would place on these questions versus others. This determination is based on a range of locally-relevant factors including the social, economic, or environmental priorities of stakeholders in that state and the extent to which stakeholders feel a question has been sufficiently answered in the context of that state.Through a broad, multi-stakeholder process, we have identified 40 important research questions that, if answered, could lay the groundwork for effective, science-based climate action in Georgia. This list of questions is best thought of as a starting point for further discussion of priorities, research in the state, and deliberation regarding policy priorities (Sutherland et al. First, in Spring 2018 we will conduct a survey to determine how professionals from Georgia rank the relative importance of the research questions we identified and to provide an opportunity for input on topics we may have missed. This will help us broaden inclusion in the question identification and prioritization process, thereby improving the robustness and policy relevance of the results Rudd . Second,


Along temperature, humidity is one of the principal environmental factors that plays an important role in various application areas. Presented work investigates possibility of distributed fiberoptic humidity monitoring based on humidity-induced strain measurement in polyimide (PI)-coated optical fibers. Characterization of relative humidity (RH) and temperature response of four different commercial PI- and one acrylate-coated fiber was performed using optical backscattering reflectometry (OBR). The study addresses issues of temperature-humidity cross-sensitivity, fiber response stability, repeatability, and the influence of annealing. Acrylate-coated fiber exhibited rather unfavorable nonlinear RH response with strong temperature dependence, which makes it unsuitable for humidity sensing applications. On the other hand, humidity response of PI-coated fibers showed good linearity with fiber sensitivity slightly decreasing at rising temperatures. In the tested range, temperature sensitivity of the fibers remained humidity independent. Thermal annealing was shown to considerably improve and stabilize fiber RH response. Based on performed analysis, a 20 m sensor using the optimal PI-coated fibers was proposed and constructed. The sensor uses dual sensing fiber configuration for mutual decoupling and simultaneous measurement of temperature and RH variations. Using OBR, distributed dual temperature-RH monitoring with cm spatial resolution was demonstrated for the first time. Distributed fiberoptic sensors (DFOSs) have a unique ability to provide spatially continuous measurement over extended distances up to hundreds of kilometers . This maConventional Raman- or Brillouin-based fiberoptic distributed temperature sensing with active (heated) sensing fiber was explored for a number of soil hydrologic monitoring applications ,9,10,11.Another category of fiberoptic DHS relies on the measurement of humidity-induced attenuation (HIA). Various concepts have been explored to incur additional optical loss to the fiber upon interaction with water/moisture. A combination of water-swellable elements and smart fiber packaging was used to induce HIA via fiber bending losses ,13. Anot2 [At the moment, approaches based on measurement of humidity-induced strain (HIS) caused by a swelling of hygroscopic fiber coating materials seem to be the most promising and practical. While other coating materials, e.g., acrylates  or TiO2 2 , have be2 ,19,20,212 . The sam2 . Neverth2 . The inc2 . In our 2 .While previous works had a proof-of-concept character and focused on validation of HIS-based sensing mechanism, in this work, we address key practical aspects of HIS-based DHS and demonstrate distributed environmental sensing that allows decoupling of temperature, strain, and relative humidity (RH) effects. Temperature and RH response characterization of four different commercial PI- and one acrylate-coated fiber is performed. The analysis addresses issues of temperature-RH cross-sensitivity, fiber response stability, repeatability, and the influence of annealing with an aim of selecting the optimal sensing fiber (s). After thorough fiber characterization, short (20 m) sensing cable is developed that allows distributed environmental measurement with mutual discrimination of RH and temperature variations at simultaneous isolation from mechanical (strain) influences. Using OBR, HIS-based distributed dual temperature-RH environmental sensing with cm spatial resolution is demonstrated for the first time. The research is carried out in the context of power cable monitoring, targeting development of water ingress sensor for subsea cable joints. Nevertheless, the presented results remain relevant in the broader context of distributed humidity sensing and the developed sensor can be of interest in various other application areas.Humidity and temperature response of five single-mode fibers (SMFs) was investigated in scope of this work. The fibers include four different commercial PI-coated fibers with different fiber-coating geometry and a standard acrylate-coated fiber as a reference. As the RH sensitivity of PI-coated fibers depends on the relative glass-to-coating area ratio , used fiFor the temperature-humidity characterization, roughly 5 m long segments were cut from each fiber and coiled into small spools with diameter of 6–8 cm. The individual spools were put into a compact shelf-type holder at separate levels and spliced together in order to allow simultaneous measurement of all fibers in series. The order of the fibers in the series as they were interrogated throughout the study is indicated in For temperature characterization, an automated climate chamber program with 10 °C temperature steps from 10 °C to 50 °C and back with 2 h holding time at each temperature level was used. Fiber temperature response characterization was performed separately at 3 different constant relative humidity levels of 10%, 50%, and 90%. For humidity characterization, automated climate chamber program with 20% RH steps from 10% to 90% and back with 4 h holding time at each RH level was used. Fiber humidity response characterization was performed separately at 3 different constant temperature levels of 20 °C, 35 °C, and 50 °C. Throughout the CC program runtime, automated backscatter measurement with Luna OBR was taken each 5 or 10 min for temperature and humidity response characterization, respectively. All SMFs were interrogated simultaneously (in series) using a 15 nm scanning range and 5 cm spectral shift resolution. Relative spectral shift curves calculated by the device native software, as well as raw backscatter data, were saved for further post-processing. Entire temperature and humidity characterization series (2 × 3 measurement cycles) was firstly performed with pristine fibers and then repeated after the fibers had been annealed for 48 h at 50 °C and 90% RH. The upper operation temperature limit (50 °C) was chosen based on preliminary investigations, which indicated that prolonged operation at temperatures above 60 °C may deteriorate linearity of humidity response of some of the fibers see . ValidatSlight inhomogeneities of the spectral shift response within individual fiber sections are most likely caused by local restrictions in free movement (expansion) of the fibers within 5 m spools. This is hard to completely avoid for tight fiber spools with such small diameters. On the other hand, our preliminary studies showed that using fiber spools with considerably larger diameter led to even more severe inhomogeneities in the measured signal. These are associated with real spatial inhomogeneities of temperature and RH distribution within the climate chamber. Therefore, the selected fiber holder design targeted maximal compactness of the fiber assembly in order to minimize the impact of spatial temperature and RH inhomogeneities in the CC. Nevertheless, part of the signal fluctuations along the fiber sections might also come from coating inhomogeneities along the fiber.To evaluate the evolution of fiber RH or temperature response throughout the characterization cycle, spectral shift values corresponding to the individual fiber sections were spatially averaged separately for each OBR trace recorded in a given measurement cycle. The extent (length) of averaged sections was kept the same for all five fibers and is indicated by shaded areas in While humidity response of PI-coated fibers followed stepwise changes of RH relatively nicely, response of acrylate-coated fiber exhibited more complicated behavior with significant hysteresis. This might be caused by thermally induced relaxation processes occurring in the coating polymer matrix, which leads to a permanent change of the coating characteristics and is typically associated with fiber longitudinal shrinkage. The effect is well known, for example, in the area of polymer optical fibers ,28 and iFor humidity cycle at this temperature, slight hysteresis became visible even for pristine PI-coated fibers as the measured spectral shift curves did not return to their original zero value a. AnnealTo further evaluate fiber temperature and relative humidity response, sensitivity of individual fibers was determined by plotting calculated section-averaged spectral shift values against corresponding temperature or RH step values. Fiber spectral shift values at individual RH or temperature steps were calculated as time-averaged values from the corresponding plateau regions of the temporal evolution curves  might be relevant strategies for obtaining reference temperature measurement free of impacts of humidity variation. However, we deem these approaches rather unpractical due to price- and/or handling-related factors. Here, two parallel sensing fibers with different temperature and RH sensitivities were used simultaneously. Spectral shift signal Effectiveness of the decoupling increases with increasing dissimilarity of sensitivity ratio Stability and reproducibility of fiber humidity response is important for the reliable sensor operation. To demonstrate the distributed environmental sensing with simultaneous measurement of relative humidity and temperature, a small-scale sensing cable was prepared using the two selected PI-coated fibers a. The fiTo test possibility of distributed environmental sensing, two sections of the prepared sensing cable were put into the climate chamber. A roughly 5-m-long section of the cable (3–8 m from the connectorized end of the cable) was coiled inside of the climate chamber. An additional 0.5-m-long section (roughly at 15 m from the connectorized end of the cable) was fed directly (straight) through the side openings of the chamber. The rest of the sensing cable was placed freely around the room. Spectral shift evolution from the entire cable was recorded during a 54-h climate chamber program with simultaneous change of temperature and RH. The program consisted of two temperature ramp cycles between 20 °C and 40 °C and a simultaneous step-wise RH cycle from 10% to 90% and back in 20% steps. Automated Luna OBR measurement every 20 min, with the same settings as for general fiber characterization, was used. To decouple the effects of temperature and RH, separate spectral shift traces from the two sensing fibers were overlaid in the postprocessing and relative change of temperature and RH were calculated using Equations (2) and (3), respectively, at each point along the sensing fiber. The process is illustrated in In this work, development and demonstration of distributed fiberoptic sensor for simultaneous temperature and relative humidity monitoring was reported. The investigated humidity measurement principle relies on humidity-induced strain of polyimide-coated optical fibers. The sensor uses dual sensing fiber configuration for mutual decoupling and simultaneous measurement of temperature and RH variations. Optical backscatter reflectometry was used as an interrogation technique throughout this work. In the first step, thorough characterization of RH and temperature response of four different commercial PI- and one acrylate-coated fiber was performed with the aim of analyzing their sensing performance and selecting most suitable candidates. Humidity response of acrylate-coated fiber was shown to have unfavorable nonlinear nature and strong temperature dependence with increasing RH sensitivity at lower temperatures. While this makes acrylate-coated fiber rather unsuitable for RH sensing tasks, its RH sensitivity still should be considered for high precision temperature or strain sensing applications, especially at low temperatures. In contrast to acrylate-coated fiber, all tested PI-coated fibers exhibited RH response with good linearity and superior stability. A similar trend of slight RH sensitivity increase at decreasing temperatures was observed for all PI-coated fibers. Depending on the application precision requirements and expected temperature operation range, the effect might need to be considered. For the temperature range considered in this work (20–50 °C), the effect may be neglected while keeping the introduced measurement error below 5% of measured RH change. In the tested range, temperature sensitivity of the PI-coated fibers remained humidity independent. Thermal annealing was shown to considerably improve RH response of PI-coated fibers in terms of minimizing the hysteresis, homogenizing the response along the fiber and increasing RH sensitivity. Based on performed analysis, the two most suitable fibers with similar temperature but different RH sensitivity were selected for development of targeted sensor. Sample 20-m sensor cable using the selected PI-coated fibers was proposed and constructed. The cable used metal spring hose to provide mechanical insulation for the sensing fibers while allowing them to interact with the environment. Using OBR and dual fiber configuration, distributed simultaneous temperature and RH measurement with cm spatial resolution was demonstrated for the first time. Although OBR was used for all the measurements in this work, the presented sensing approach should be readily employable with other DFOS techniques such as phase-sensitive OTDR. Similarly, all qualitative conclusions on fiber performance remain generally valid.


The evidence base for micronutrient powder (MNP) interventions predominantly consists of quantitative studies focused on measuring coverage, utilization, and/or biological outcomes. We need other types of studies to broaden the scope of our knowledge about determinants of MNP programme effectiveness. Addressing this knowledge gap, this paper focuses on the process of designing an ethnographic research protocol to obtain caregivers' perspectives on the factors that influenced their use of intervention delivery services and their adherence to MNP recommendations. The research was undertaken within the context of formative evaluations conducted in Mozambique and Ethiopia. Ethnography provides a means for acquiring and interpreting this knowledge and is an approach particularly well suited for formative evaluation to understand the response of a population to new interventions and programme delivery processes. We describe decisions made and challenges encountered in developing the protocol, and their implications for advancing methodology in implementation research science. In addition to a core team of three investigators, we added an “advisory group” of 10 experts to advise us as we developed the protocol. The advisory group reviewed multiple drafts of the interview protocol and participated in mock interviews. In the protocol development process, we faced the issues and made decisions about concerned gaps in content, cultural adaptations and comprehension, and interview guide structure and format. Differences between the core team and the advisory group in methodological approaches to the structure and content of questions call attention to the importance of establishing greater communication among implementation scientists working in nutrition interventions. Pretesting with an advisory group in the process of developing an ethnographic interview protocol for process evaluation played a vital role to improve structure and content of the protocol.A primary theme in the advisory group's feedback was criticism of the “conversational tone” of the open‐ended questions. A second, related concern was the balance between “broadness” and “specificity” of questions.Findings illustrate how fundamental features of ethnography are different from survey‐type research.Improvements to the protocol, along with results of using it described in accompanying papers of this supplement, demonstrate the value of involving an advisory group in implementation research.1Although there is substantial evidence to support the selection of a micronutrient powder (MNP) intervention as part of an integrated strategy to address infant and child undernutrition in low‐ and middle‐income countries  and/or to explain programme outcomes Phase IIICore team revisions to the caregiver interview guidePhase IVPretesting, field testing, and cognitive testingThis paper covers Phases I–III. We do not include Phase IV or describe in detail the revisions that were necessary to adapt the guide for the different delivery systems that were used in Ethiopia and Mozambique. We made the decision to omit discussion of these topics to devote sufficient attention to a formative evaluation activity that we feel has received less attention in nutrition, namely, initial guide development. In our view, research guidelines on pretesting and field testing instruments are more systematized, more widely available, and more commonly utilized by implementation researchers, compared with initial development of interview tools  was organized into four phases:Collins, .2.3A list of key topics and questions to address was generated based on a review of the literature on MNP interventions  interactions with the delivery system; (b) acceptance and utilization of MNP; (c) beliefs, perceptions, and behaviours related to MNP; (d) child food preparation practices; and (e) child feeding practices. In the two study sites, different questions were sometimes required because of the differences in the delivery systems in the two programmes: In Mozambique, the plan was for caregivers to receive vouchers from NGO or government health workers and redeem them for MNP sachets  at local shops. In Ethiopia, the MNP sachets  were distributed directly through government health extension workers.Phase I was the responsibility of a small team, hereafter referred to as “the core team” . Two activities were used to develop the first draft of the interview guide.After the initial draft of questions was prepared, the wording of questions was examined to ensure they accorded with good ethnographic interviewing techniques and to avoid imposing preconceived assumptions Seidman, . At this2.4Seven experts assisted by conducting mock interviews with our draft interview guide. They were assigned to assume the roles of different types of respondents .Three experts with research experience were asked to complete an in‐depth review of the interview guide, which involved reviewing each question for all types of respondents.After the core team completed a provisional draft of the interview guide, the next step was to seek advice from an informally constituted group of experts, hereafter referred to as the PAG  took approximately 3 weeks to complete.Finally, it is important to note that the development and critical review of the caregiver interview guide was undertaken in conjunction with the development of a general programme impact pathway model for caregiver MNP adherence as previously described by Tumilowicz et al. .3Table 3.1Phase II revealed several topics that needed to be explored more thoroughly than we had initially realized when we constructed the guide. These topics concerned the caregiver's experiences with intervention delivery, their sources of information about MNP and its recommended use, and the potential impact of social support networks on the caregiver's acceptance and utilization of MNP. For the Mozambique programme, which used a voucher system, a brief introductory module served to screen for MNP voucher receipt and redemption. However, many of the advisory team members felt that questions should be added to discover what the caregiver's experience was when she received and redeemed the voucher. Several PAG members noted a gap in investigating caregivers' exposure to various sources of information about MNP and how to use it. They recommended asking questions specifically about who explained to caregivers how to use MNP, what they were told, the setting in which they were told , and what programme materials, if any, caregivers had received to aid in their understanding of the product. One expert with experience in maternal, infant, and young child nutrition programme development and implementation stressed the role social support can play in a caregiver's involvement with an intervention and recommended adding several questions to further explore the attitudes and behaviours of a caregiver's social support network to determine how those may have influenced her acceptance and utilization of MNP, either positively or negatively.3.2Pretesting in Phase II revealed words, phrases, concepts, and questions that needed to be modified. For instance, a note for the interviewers regarding the question, “Is there anything parents can give to help children grow?”, suggested that they might ask about “teas or tonics,” as an example. However, one expert with knowledge of the local culture noted that “tonics” would not translate well into the local language, nor would caregivers be likely to have the same understanding of “tonics” as the interview guide developers or perhaps any understanding of them at all.3.3after respondents were asked to describe behaviours with MNP, so that the line of questioning about sources of information and instructions did not influence how respondents described their own behaviours.PAG members provided insights into how the sequence of questions could be changed to (a) avoid the potential for bias; (b) enhance the logical flow of questions; and (c) minimize the frequency of skip patterns. They highlighted questions that might be redundant and could therefore frustrate participants. They suggested ways the interview guide format could be modified to improve the interviewers' experience. To minimize bias, PAG members suggested that follow‐up questions about respondents' sources of information about MNP should be asked Although the core team recognized the complexity of the interview guide during the initial development phase and attempted to address this through format changes, our experts still raised concerns about frequent skip patterns. As the status of the respondent relative to use  was not known before the interview began but emerged in response to the use questions, the original plan was to use a single caregiver interview guide with all the respondents. One PAG member recommended creating separate “passages” for different types of respondents in the module assessing the caregiver's behaviours with using MNP. These separate passages would eliminate the need for skips in the section on use behaviour, prevent confusion, and ease the burden on interviewers. We subsequently took the recommendation further and created separate interview guides for the different types of respondents. As soon as it was clear what type of user the respondent was, the interviewer simply reached for a separate interview guide.However, the use of different guides did not entirely eliminate skip patterns because even caregivers in the same intervention respondent type category had unique experiences and perspectives to share that needed to be embraced, anticipated, and accounted for.One PAG member, who conducted an in‐depth review of the interview guide, recommended placing all questions regarding intervention delivery in Mozambique, including voucher receipt and redemption in the same module to make it easier for caregivers, rather than asking intervention delivery questions in both the opening and closing modules, as was the initial plan.Related to the interview guide structure and format, and similar to the core team's own discussions, experts shared their ideas about how to handle “yes/no” questions. We initially included “yes/no” questions and skip patterns to distinguish who needed to answer which questions. However, expert feedback about the complexity of skip patterns and discussions about how to best elicit all the information for the formative evaluation led us to rethink these questions and the interviewer instructions that came with them. We recognized that not only would additional skip patterns be complicated for the interviewers but they could also prevent the interviewer from collecting valuable information. Thus, instead of using “yes” and “no” options on the interview guide, with skip patterns and separate follow‐up questions , we decided that “yes” and “no” answers should be avoided in favour of questions that provided insights about the caregiver's experiences. For example, instead of prefacing with, “Do you remember the first time your child got food with MNP?” the question directly asks about the experience, “Thinking back to the first time your child got some food with MNP, do you remember how he or she took it; what the child's response was to the food?”Members of the PAG raised concerns about whether the interviewers would be able to elicit the necessary information. They also emphasized the need for interviewers to have a solid understanding of the technical aspects of MNP and the intervention, as well as strong interviewing skills to effectively probe and prompt on answers to open‐ended questions.Finally, with respect to format, another finding of note is that none of the experts expressed concern about the use of questions that were framed in a “survey‐like format” in what was positioned as “a qualitative study.”3.4A primary theme in the feedback from the expert team was criticism of the “conversational tone” of the open‐ended questions. A second, related concern was the balance between “broadness” and “specificity” of questions. The differences in methodological approaches were revealed in several ways, outlined below.A central piece of feedback from one expert with extensive MNP programming and research experience was to make the interview guide more straightforward by simplifying and condensing questions and removing extraneous instructions because introductory language or “pleasantries” ran the risk of “getting lost in translation.” For example, instead of phrasing a question as: “You have told me what happens to leftover food with MNP, but I also wonder, does anyone else in the family besides (child name) also get (MNP product name)?” a PAG member suggested we simply ask: “Does anyone else in the family get (MNP product name)?”Following basic ethnographic techniques, the core team explicitly crafted the questions to elicit “emic” perspectives and reduce the influence of the investigators' or interviewers' perspectives. However, PAG experts made numerous suggestions to rephrase questions to be more direct, which in some instances led to tension between maintaining an ethnographic approach but ensuring specific information of interest was still elicited. For example, as part of exploring caregivers' interpretations and perceptions of MNP, we asked: “Are there times when it is particularly more important to give infants and young children vitamins?” One expert team member suggested asking: “Did you give your child MNP the last time he or she was sick?”There were also tensions regarding the instructions for interviewers on using probes. Relating to the concern about information to improve the programmes, there were lively discussions about whether that information would come out naturally as part of a caregiver's answer to a broader question followed by probing, or whether separate, more specific questions were required to elicit the desired information. Some PAG members were concerned about relying too much on probes and follow‐up questions for fear that the suggested probes would be overlooked or forgotten by interviewers in the “heat of the interview.”Discussions between PAG members and core team members also concerned the issue of appropriate specificity of the probes themselves. Some thought it was important for probes to be explicit so that interviewers would know the exact information that was important to obtain, whereas others promoted the idea that the listing of potential probes should be more general to avoid unduly influencing respondents.Please tell me the steps you followed when you prepared the food with MNP. I'd like to understand a little more about how you mixed the MNP with (food name or foods) when you fed it to (child name). Can you explain to me how you did this?We wrote instructions to help interviewers lead the respondents through the step‐by‐step process, such as asking “and then what?” after the caregiver described each step. We listed topical probes to capture different parts of the preparation process, such as the consistency and portion of food to which MNP was added, if the whole MNP sachet was used, and at what point in the food's preparation the MNP was added. The PAG members were not uniform in their suggestions concerning this important question. The suggestions included (a) making each of the preparation step probes into separate questions, (b) making the questions more specific to ensure the information was obtained, and (c) providing probing suggestions that consisted of few words to cue interviewers to topics of interest or, alternatively, writing out the probes as full questions so interviewers knew exactly what to say. For example, one PAG member suggested we ask: “Did you add the MNP to the food while it was still cooking?” In the final version, we included the probe: “Do you remember at what point in the food preparation or cooking process the MNP was mixed in with the food?” We reasoned that we would still learn when she added the MNP, but the information could be elicited in a less biased and more emic way. In the analysis, the information obtained from this question turned out to be essential to determine whether caregivers actually followed the preparation instructions they should have been given by the health workers.An example that illustrates both “specificity” and “probe issues” in experts' feedback is a question asking caregivers to describe how they prepared foods with MNP. We originally framed the question as follows:In contrast to the foregoing concerns, one PAG member with extensive MNP research experience, and who was also more familiar with a focused ethnography approach and the focused ethnographic study on infant and young child feeding manual  and question construction (probing). In Phase II, with the essential inputs from the PAG, the implications of differentiation became fully apparent. After the fact, it seems obvious, but the implications of differentiation, particularly the methodological implications, only emerged over the course of developing the data collection instrument. In Phase III, we collectively developed solutions to the challenges of differentiation with respect to the structure of the interview schedules, as well as interviewer recruitment, training and monitoring, and resource allocation.The study results illustrate the ways in which some of the fundamental features of ethnography are different from survey‐type research. The discovery that some PAG members were uneasy with, or even negative about, some of the features of good qualitative interview techniques was surprising. It is an important finding and raises larger issues that require exploration to identify the reasons for the tensions related to methodological approaches and what can be done to ameliorate them.Throughout the process of developing and implementing the research, the ethnographically trained and oriented members of the core team were committed to maintaining the principles of ethnographic interviewing to accurately capture caregivers' experiences with MNP. When we changed questions and/or probes, the end results were closer to the ethnographic rather than the quantitative survey end of the spectrum. The interview guides developed for Mozambique through the process described here is available in Beyond the basic premise that caregivers are often best placed to offer insights into whether or how a nutrition intervention and its mode of delivery are functioning, there are inherent advantages of using of ethnographic methods in formative evaluation (Fetterman, As noted above, the research results we obtained by using an ethnographic approach are described in other papers in this supplement (Pelto et al., There is a relatively large body of literature of valuable ex post facto analyses of how well‐intentioned nutrition and public health interventions failed to achieve their intended impact because of cultural, social, and behavioural factors in both the delivery systems and utilization systems in which the interventions took place. This scientific literature has a long‐time depth, dating back many decades, and continues to grow as social science investigators conduct evaluations of nutrition and public health interventions. However, at present, there are few published examples of formative evaluations that systematically explore caregivers' perspectives to understand how delivery and utilization processes affect programme outcomes or impacts. This lacuna is a significant gap in supporting the application of ethnography in implementation research.In our view, ethnographically trained implementation scientists need to do a better job of documenting the benefits of expanding and employing their research modalities, explaining the different types of techniques of their mixed method approach, and addressing the concerns of quantitative researchers. At the same time, quantitatively oriented investigators need to be better informed about the benefits and contributions of ethnography. There are, undoubtedly, multiple reasons for the slow progress on application of mixed methods. Some of these involve fundamental beliefs about what constitutes science and scientific rigour. Some of it can be attributed to the “silos” that are created by social, academic, and institutional structures, as well as communication modalities and channels.A systematic and empirical exploration of the reasons for the study findings concerning the tensions that were revealed in Phase II of the study is beyond the scope of this paper. However, we hope that these results, which highlight the need for better communication among implementation scientists working in the field of nutrition interventions, will lead to further discussions and new actions to support sound and effective formative evaluation, as well as other aspects of implementation research in nutrition.The authors report no conflicts of interest.CHS, AT, and GHP developed the paper concept; CHS conducted the PAG pretesting and analysis and wrote the first draft of the manuscript; AT and GHP provided intellectual content; all authors read and approved the final version submitted for publication.Data S1: Supporting informationClick here for additional data file.Data S2: Supporting informationClick here for additional data file.Data S3: Supporting informationClick here for additional data file.Data S4: Supporting informationClick here for additional data file.


In this work, we demonstrate that the electromagnetic properties of graphene oligomer can be drastically modified by locally modifications of the chemical potentials. The chemical potential variations of different positions in graphene oligomer have different impacts on both extinction spectra and electromagnetic fields. The flexible tailoring of the localizations of the electromagnetic fields can be achieved by precisely adjusting the chemical potentials of the graphene nanodisks at corresponding positions. The proposed nanostructures in this work lead to the practical applications of graphene-based plasmonic devices such as nanosensing, light trapping and photodetection. Recently, an increasing number of subwavelength components and structures have been designed and manufactured based on metamaterials (MMs) which get spotlight by the versatility of controlling the electromagnetic (EM) behaviors . MMs sup2 hybridization of carbon atoms in the honeycomb lattice structure. Due to the surpassing behaviors in electronics as well as photonics of graphene, various research groups investigate graphene with different methods to create plasmonic structures that exhibit lower losses, higher confinement and tunability of the EM fields [Graphene is one two-dimensional material made up of spM fields –23. GrapM fields –26. GrapM fields . GraphenM fields . By chanM fields . However12h symmetry is able to sustain two plasmonic modes in calculated range. Further utilization of graphene oligomer relies on the precise control of local chemical potential of graphene. By selectively varying chemical potentials of graphene oligomer, the two innate plasmonic modes are profoundly modulated. Tuning the chemical potential of prominent graphene nanodisks in two plasmonic modes respectively has different influence on two plasmonic modes. The change of chemical potential of intersection part between the two plasmonic modes intensifies both two plasmonic resonances and leads to degeneration of plasmonic modes. In addition, the change of chemical potential of central graphene nanodisk also significantly affects the EM properties of graphene oligomer. The simulated results show that the graphene oligomer possesses high tunability and flexibility, and provides new degrees of freedom for designing plasmonic nanodevices capable of tailoring two-dimensional light confinement.To verify the effect mechanisms of PMs based on graphene, a numerical study on the graphene oligomer consisting of 13 equal-sized graphene nanodisks has been systemically conducted by intentionally varying chemical potential of partial graphene in this work. The graphene oligomer with Dσg is the complex surface conductivity of graphene, ŋ0=377 Ω stands for the impendence of the free space, and k0 = 2π/λ is the wave number of the light in air. The complex surface conductivity σg of graphene monolayer is modeled by Kubo’s formulation, which consists of contributions from both intraband electron-photon scattering σintra and interband electron-electron transition σinter [In our model, the graphene is treated as one thin film with one atom layer thickness ∆ and modeled by a complex permittivity ε .1\documen σinter ,2\documeℏ is the reduced Planck constant, kB is the Boltzmann constant, T is the temperature set as 300 K, τ is the momentum relaxation time set as 0.5 ps, ω is the radian frequency, and μc is the chemical potential of graphene.In these equations, e is the charge of an electron, 12h symmetry |/|Re(neff)| is significantly small. So the real part of neff mainly effect the calculate results and the imaginary part of neff has little effect on our model with chemical potential changing. We therefore neglect the effect of imaginary part of neff in this study.We incorporate graphene nanodisk arrays into a graphene oligomer with Dtry Fig.  to invesσext is obtained as σext = σsc + σabs, where σsc corresponds to the scattering cross-sectionσabs, is determined byThe electric fields and extinction spectra of graphene oligomer are calculated in the commercial finite element method (FEM) software, COMSOL Multi-Physics, RF Module. The extinction cross-section 0 is the incident intensity. In these equations, IEquation  is takenμc. By varying μc of the whole graphene oligomer from 0.4 eV to 0.6 eV, both two plasmonic resonances become intense, and the positions move to higher frequency range simultaneously. The distinct enhancement of absorption in graphene oligomer is ascribed to the promotion of carrier density with increasing μc, which creates an optical gap where plasmons avoid being quenched through coupling to electron−hole pairs (Landau damping). The increase of virtual electron-hole pair transitions allowed gives rise to the significant interaction of coherently coupled graphene nanodisks which intensifies extinction maximum [μc = 0.5eV as the benchmark and the two peaks labeled by A0 and B0 represent two different plasmonic modes and the corresponding electric fields are presented in Fig. 0, the hot spots mainly concentrate on the eight nanodisks on the top and bottom, and especially focus on the four nanodisks on the highest and lowest positions in the nanostructure. For peak B0, the hot spots mainly concentrate on the eight nanodisks on the left side and right side, and the brightest four nanodisks are on the most left and right positions in the nanostructure, which is perpendicular to the mode of peak A0. Based on the different electric field distributions of peak A0 and B0, we define the mode of peak A0 as Y mode and the mode of peak B0 as X mode for a clear expression. The four brightest graphene nanodisks in Y mode are extremely dark in X mode and vice versa. Another four graphene nanodisks composed of a square are relatively bright both in Y mode and X mode defined as the intersection part. We divide the peripheral graphene nanodisks into three parts with different chemical potentials μc1, μc2 and μc3 respectively , a new resonance peak appears obviously in the extinction spectrum  (PMMA) as an electron beam resist is used to pattern the graphene film to produce the proposed nanostructures, and the exposed area is etched away by the oxygen plasma, remaining the pattern of graphene protected by a PMMA layer with subsequent lift-off using acetone. Then the device is ready for test. The chemical potential can be tuned via manipulating chemical and electrostatic doping. For chemical doping, local chemical potential change can be realized by exposing the required graphene nanodisks to HNO3 vapor and simultaneously preventing the contact between other graphene nanodisks and HNO3 vapor. For electrostatic doping, an appropriate top gate configuration may locally manipulate the chemical potential of graphene by supplying top gate voltage.In practice, continuous atomic single-layer of graphene is first grown using an optimized chemical vapor deposition method with CHIn conclusion, we have demonstrated the versatility of the graphene oligomer to modify the EM behaviors and spectral lineshape by varying chemical potential of graphene at the nanoscale. The characteristics are summarized from the electric fields and extinction spectra of the various chemical potentials. First, by changing the chemical potential of two graphene nanodisks in Y mode and X mode respectively, a flexible variation of two resonance peaks appears in extinction spectra. The two resonance peaks can be enhanced or reduced by changing the different chemical potentials of graphene oligomer. Second, increasing the chemical potential of intersection part intensifies the both two resonance peaks and gives rise to degeneration of Y mode. Third, high chemical potential of central graphene nanodisk is able to support a strong resonance peak and simultaneously restrain two innate resonance peaks. The dependence of the graphene oligomer on chemical potential suggests that one can modify the EM behaviors of the graphene nanostructure with chemical potential without modifying the geometry. The previous studies based on graphene nanostructures can only change one absorption peak by changing chemical potential of whole graphene –23, but