Microbial communities play a significant role in the functioning of the ecosystem in the cold mountain desert of Eastern Pamir, a region that is characterized by extreme environments with limited nutrient and water availability and sparse vegetation. This study aims to investigate the taxonomic composition and structure of bacterial endolithic (rock matrix colonizing) assemblages and soil-inhabiting communities that occur in the Eastern Pamir Mountains, and to compare the composition and structure of both types of communities looking for general patterns and trying to identify the connectivity between these types of microbial assemblages. The taxonomic composition of Pamirian endolithic communities and soil-inhabiting microbial consortia (biocrust communities) exhibit similarities to communities from cold and hot deserts, but they also harbor taxa, which are possibly novel species or which, so far, lack reference sequences in the databases. The endolithic communities occurring in three subregions of Eastern Pamir are characterized by high heterogeneity and cannot be grouped according to the subregion, while the distribution of Cyanobacteria in the soil crusts demonstrates the similarities between the communities within the subregion reflecting regional differences. We also found connectivity between both habitats concerning the occurrence the same taxa .Chroococcidiopsis, Gloeocapsopsis and Wilmottia. Despite the niches’ specificity, which is related to the influence of microenvironment factors on the composition and structure of endolithic communities, our results illustrate the interrelation between the endoliths and the surrounding BSCs in some regions. The structure of cyanobacterial communities from BSC was the only one to demonstrate some subregional differences. Microbial communities found in arid environments are commonly represented by biological soil crusts (BSCs) and endolithic assemblages. There is still limited knowledge concerning endoliths and BSCs occurring in the cold mountain desert of Pamir. The aim of the study was to investigate the composition and structure of endolithic bacterial communities in comparison to surrounding BSCs in three subregions of the Eastern Pamir (Tajikistan). The endolithic and BSC communities were studied using culture-independent and culture-dependent techniques. The structure of the endolithic bacterial communities can be characterized as Actinobacteria–Proteobacteria–Bacteroidetes–Chloroflexi–Cyanobacteria, while the BSCs’ can be described as Proteobacteria–Actinobacteria–Bacteroidetes–Cyanobacteria assemblages with low representation of other bacteria. The endolithic cyanobacterial communities were characterized by the high percentage of Chroococcidiopsaceae, Nodosilineaceae, Nostocaceae and Thermosynechococcaceae, while in the BSCs were dominated by Nodosilineaceae, Phormidiaceae and Nostocaceae. The analysis of 16S rRNA genes of the cyanobacterial cultures revealed the presence of possibly novel species of  Arid environments constitute a large part of the Earth’s landmass. They are sensitive to climate changes and have a tendency for expansion . Thus, tBoth types of microbial systems are significant for the functioning of desert ecosystems, including their role in basic biochemical processes such as carbon and nitrogen sequestration, nutrients cycling, biological rock weathering and pedogenesis (lithobionts), soil-geomorphic processes and stabilization of soil (soil-inhabiting microorganisms) ,20,21,22There are only a few studies comparing the composition and structure of both niches in the desert ecosystems of the Earth and they concerned communities from Antarctica ,20 and tThe previously described differences in climatic conditions prevailing across the high mountains plateau, and divergent hydrology and geomorphology of Eastern Pamir ,5,29,30,Taking into account the specific climatic and geological conditions and geographical differences of localities from Eastern Pamir, analyzed within the present study, we hypothesize that: (i) there are regional differences in the distribution of taxonomically different groups of endolithic bacteria occurring in the Eastern Pamir compared to those described from other cold and hot deserts; (ii) geomorphology of region and climate have a great influence on diversity and structure of the endolithic communities occurring in different subregions of Eastern Pamir and (iii) there is connectivity between communities occurring in the endolithic and edaphic habitats.Hence, the aims of the present study were (1) to investigate the taxonomic composition and structure of endolithic bacterial community, which occur in different types of rocks and along geomorphologically different zones of the Eastern Pamir Mountains; (2) to characterize the diversity and structure of biological soil crust (BSC) systems in these subregions; (3) to estimate the contribution of cyanobacteria at both types of communities (endolithic and edaphic) and (4) to compare the composition and structure of both types of communities looking for general patterns and trying to identify the connectivity between these types of microbial assemblages.The field area of the study comprises Eastern Pamir, which is located in the eastern part of the Gorno-Badakhshan province of Tajikistan. The majority of Eastern Pamir is a barren area with sparse vegetation, where the biodiversity spots are concentrated around the lakes of Pamir, hot springs and, sometimes drying out, rivers. The top of the mountains, where environmental conditions are even harsher than at lower altitudes, are characterized by rocky surfaces and widely distributed endolithic colonization. The geology of Eastern Pamir is very complex and based on the generalized classification, the area can be divided into three main zones: the northern part/zone dominated by volcanic rocks; the central part dominated by sedimentary rocks, and the southern zone mainly represented by metamorphic bedrock ,30. For The study took place in three subregions of Eastern Pamir, which fall within the main geological zones of the Pamir Mountains, near lakes; Karakul—the northern zone, Rangkul—central zone and Bulunkul—the most southern zone ,30 The sForty-three of the studied samples of endoliths have been collected in July 2017, which according to the recently developed study , shall bThe samples with endolithic colonization have been split up into four subsamples intended for (1) for molecular analysis, (2) isolation of cyanobacteria, (3) SEM microscopy and (4) the back-up sample. The BSCs were sampled from areas surrounding the rocks from which the endolithic specimens came. In some sampling areas, the diversity of the rock types was high, while in the others the soil seemed to be more heterogeneous and the representations of rocks within the sampling area were less diverse. Thus, the sampling was aimed to screen different types of microhabitats colonized by microorganisms as accurately as it was possible. The diversity and distribution of cyanobacteria in the endolithic communities were compared with these parameters of the soil-inhabiting communities. The sampling of endoliths and BSC was performed concurrently.Twenty-seven samples of the BSCs were collected to characterize the diversity, composition and structure and the distribution of bacteria in this microhabitat and to compare with the endolithic microhabitats. The subsampling of the BSCs was performed in a similar way as in the case of endoliths, but instead of SEM examination, the samples of biocrusts were tested through chemical analysis of the soil, which is described in the next section.The chemical analysis of the soil was performed in the Laboratory of Biogeochemistry and Environmental Conservation, at the University of Warsaw. Dried samples of soil crusts have been ground and sieved with a 1 mm mesh sieve. The pH of the soil and the mineral parts content was investigated based on samples’ ignition at 550 °C for 90 min. Total C and total N . Total K, Na, Ca, Mg and Fe contents in soil have been estimated after the digestion in nitric/hydrofluoric acids (10:1) with Speedwave 4 microwave mineralizer  ,34.The environmental samples of endoliths were examined under the FE-SIGMA VP microscope  with an energy-dispersive (EDS) detector , based on the procedure described in our previous work . Small fThe cross-sections of rock samples were prepared to assess the available pore space (porosity) of the rocks. The porosity was analyzed based on two parameters: the mean grain size (MGS), and the mean grain area (MGA). Up to 10 images were done, based on the cross-section per sample using SEM. Next, the images were binarized and analyzed using Gwyddion software according to the user guidelines instructions .v/v in phosphate buffer), then postfixed in osmium tetroxide (1% w/v in phosphate buffer) and finally dehydrated in a graded ethanol series before embedding in Spurr’s resin. Ultrathin sections (70 nm) were post-stained with lead citrate and observed in a JEOL JEM-1011 transmission electron microscope.The ultrastructure of cyanobacterial cells was analyzed using transmission electron microscopy (TEM). The samples were prepared following the protocol described by de los Ríos and Ascaso . The cyaFragments of rocks with endolithic colonization have been isolated and inserted into Petri dishes with solid (1.5–2% agar) and liquid WC or BG11 medium ,38. The Selected cultures were restreaked, then purified by washing in ultraclean water and maintained in 50- or 100-mL Erlenmeyer flasks containing BG11 or WC. Next, four strains were prepared for TEM analysis and the sequencing of two regions from the cyanobacterial genome, a fragment of the 16S ribosomal RNA gene and the 16S-23S internal transcribed spacer (ITS).®Soil DNA Kit  following the manufacturer’s protocol. The extraction was repeated three to five times per sample until satisfactory DNA quality has been reached. The amplification of a targeted fragment was conducted using a primer pair of 341 f/785 r [The sample preparation for DNA extraction has been described previously ,28. Extr f/785 r  and HotS f/785 r . The seq f/785 r  and 373RPaired-end reads have been processed using version 2020.11 of the QIIME2 environment . The “deThe complementary sequences of 16S and 16S-23S ITS were joined into contigs using SeqMan software . The initial identification of the sequences was performed using the BLAST algorithm . The mulThe analysis of the physicochemical parameters of the soil revealed the remarkable fluctuation of studied variables within each subregion. The most stable pH values were found in the Rangkul area where the mean pH value was 7.94. In Karakul, it varied between 7.26 and 8.2 and in the Bulunkul area between 7.7 and 8.7. The electric conductivity varied much more than pH between the subregions; the lowest EC was detected for the sample F23 (Karakul) (5 µS/cm), while the highest was identified for F13 (Rangkul) (1530 µS/cm). The mean values of total nitrogen concentration calculated for subregions were lowest in Karakul (0.7 g/kg), and highest in Rangkul and Bulunkul (0.1 g/kg), while the mean values of total carbon were rising from the Bulunkul (17 g/kg) through Rangkul (19.1 g/kg) and was highest in Karakul (26 g/kg). Details concerning the values obtained for other chemical parameters of the soil such as the concentration of Fe, Na and Ca are provided in the 2 mean grain area; quartzite) and 14.72 µm2 . However, the grain sizes also varied between the samples of granites and quartzites, with mean pore sizes of 7.82 µm2 and 6.12 µm2 respectively, while the mean grain size of conglomerates was a little bit bigger (8.0 µm2). The porosity of other rock types of the reference samples was characterized as similar to the main sample set and can be described as follows: the mean pore size of the conglomerates was similar to calcites, MGS of pegmatites in granites, the diorites, kaolinite and regolith were close to limestones. For the amphibolites, similar parameters as for the quartzes were obtained. The mean grain area (MGA) can be considered as a parameter reflecting the weathering rate of studied rocks, the highest value of which was noted for the granites  and 21,874 (metagenome obtained from amphibolite). The dominant phyla in endolithic microhabitats were Actinobacteria , Proteobacteria , Bacteroidetes (Bacteroidota) , Chloroflexi  and Cyanobacteria (5.2%). The number of reads identified as those that originated from chloroplasts accounted for an average of 0.7%. At the phylum level, the granites, quartzites, limestones, calcites and conglomerates had a similar composition . The cluThe comparative analysis of the structure of both types of communities revealed the prevalence of Proteobacteria in soil-inhabiting communities ; with Actinobacteria being the second largest group. A higher percentage of Proteobacteria was observed only for the Karakul region.Despite the remarkable differences in the soil chemistry identified for different sampling sites within the subregions, the relative abundance of bacterial phyla did not vary significantly. For this reason, in this study, the plot presenting the composition and structure of BSC is given for studied subregions rather than for single samples. The clustering analysis of endolithic and edaphic communities showed that communities occurring in the amphibolites and kaolinite in the Karakul subregion were more comparable to the BSCs than to other endolithic assemblages. They formed a well-defined cluster with a high level of similarity .The NMDS analysis based on the structure of both types of communities demonstrated that, in rare instances, communities grouped according to localization; this was the case for a few samples of endoliths and BSC from Bulunkul. Thus, some similarities in structure were detected for these samples. Some of the endolithic and BSC communities collected from the most arid mountainsides, and those from the area near the Uisu glacier in the Karakul subregion, and a few BSC and endoliths from the driest mountain slopes in the Rangkul area, were characterized by similar structure and were grouped in the NMDS plot . The endAlpha diversity analysis performed for lithobiontic assemblages and BSC revealed that endolithic communities were characterized by slightly lower diversity. However, the variability of diversity among samples was high in endolithic communities . The mosThe BSCs’ communities demonstrated the maximum and minimum value of Pielou’s evenness index among the communities from the subregion of Karakul; with the highest value being noted in the sample F16 (J = 0.96) (close to the Lake Karakul) and the minimum value (J = 0.91) in sample F20 from the mountainside in the Karakul subregion, far away from the lake. The number of observed ASV (observed features) fluctuated between 167  and 697 . Faith’s phylogenetic diversity was the lowest in F07 (PD = 25.97) and the highest in sample F16 (PD = 62.61).p < 0.05) (p < 0.05) and with the Shannon diversity index, and the number of observed features (observed ASVs) . Other significant correlations occurred between all the diversity parameters and the number of bacterial reads. The cyanobacterial reads did not correlate significantly with these parameters or with bacterial reads. Additionally, the diversity parameters correlated positively with each other, as did some chemical elements with each other  . We alsoch other . The co-occurrence of bacterial taxa in endolithic and edaphic niches has been analyzed using artificial networks. Network analysis on the basis of the most abundant ASVs occurring in the endolithic niche allowed for the identification of a core community and the identification of the relationships between the most abundant families. We have noted a high contribution of Micrococcaceae, Nitriluptoraceae and Euzebyaceae in Actinobacteria, Rhodobacteriaceae, Sphingomonadaceae and Xanthomonadaceae in Proteobacteria, Truperaceae in Deinococcus-Thermus and Chroococcidiopsidaceae, Thermosynechococcaceae and Oscillatoriaceae in Cyanobacteria, and families KD 4-96, AKIW781 and JG30-KF-CM45  in Chloroflexi A. The MiThe most abundant bacterial families identified in the BSC were represented by Xanthomonadaceae and Sphingomonadaceae belonging to Proteobacteria, Flavobacteriaceae and Cytophagaceae from Bacteroidetes, Iamiaceae, Nitriliruptoraceae and Euzebyaceae belonging to Actinobacteria, Pirellulaceae belonging to Planctomycetes and finally Nodosilineaceae, Nostocaceae, Coelofasciculaceae and Oscillatoriaceae belonging to Cyanobacteria B. Some AComparative analysis of co-occurrence of microorganisms at the family level in endolithic and edaphic niches revealed some differences in the abundance and types of ASVs representing the same families. For example, Nodosilineaceae occurring in both types of communities was not abundant in the endolithic system. Consequently, this family is absent in the network plot performed for endolithic microbial communities.We observed comparatively higher heterogeneity in the composition and structure of cyanobacteria between different endolithic samples from the same area than between communities from different regions. The structure of cyanobacteria in the BSC demonstrated divergence in the communities from different regions and lower heterogeneity among samples from the same region. The highest contribution of Cyanobacteria (7.3% on average) to the endolithic community structure was found in the granites from Karakul . These gThe structure of endolithic cyanobacterial communities was characterized by high variability. The presence of the Chroococcidiopsidaceae family was a similar feature of all the rock types collected from the Bulunkul subregion. They were also identified in limestones, calcites, and conglomerates from Rangkul, and in quartzites and a coralloid from Karakul. The family Chroococcidiopsidaceae was present in 53% (23) of the studied samples of endoliths. Other abundant families were Nostocaceae, Nodosilineaceae and Thermosynechococcaceae. We identified Sericytochromatia (1.2% on average) in 8 out of 12 types of rocks. Vampirovibrionia were noted only occasionally and accounted for an exceptionally low mean percentage (0.43% on average) of the community. The cyanobacterial communities occurring in the soil in the Bulunkul subregion were characterized by the dominance of Phormidiaceae (57%) with Nodosilineaceae (22%) being the second largest group, while in the Rangkul and the Karakul communities Nodosilineaceae (27.8% and 34.6% respectively) and Nostocaceae (24% and 20.4% respectively) prevailed. Together, they accounted for more than 50% of the cyanobacteria in the communities in both subregions. However, there were also differences in the taxonomic composition and relative abundance of cyanobacterial families occurring in individual samples from studied subregions .Chroococcidiopsis in coralloid (CK) and Oscillatoriaceae (Oscillatoria) in diorite (DK). In terms of the SILVA classification, the sequences of Nodosilinea (which were ubiquitous in BSCs in Eastern Pamir) are remarkably similar to Nodosilinea nodulosa, which is known for its ability of nitrogen fixation. The same type of ASV was also noted in endolithic communities. Nostocaceae, which were an abundant component of both types of communities, were highly represented by the ASV identified as Nodularia and Tolypothrix , Phormidium spp. (isolated from 8 samples) and Leptolyngbya spp. (isolated from 8 samples). Nodosilinea sp. were isolated from five samples, while Nostoc-like morphotypes were isolated from four samples  from which the strain was isolated. However, no reference sequence of this species features in the databases. The strain E122 of the filamentous cyanobacterium was identified as Phormidium sp. based on the morphology, but 16S phylogeny and ultrastructure of the cells demonstrated it should be identified as Wilmottia sp.  was isolated from an environmental sample of granite from Karakul (GC1K). The strain CP24R (E121) and strain CP28 (E122) were obtained from samples of limestones from the Rangkul subregion (L22R and L28R respectively), while strain CP49R (E124) came from the sample of quartzite collected from Karakul QC2K. Endolithic strains E119 (isolated from granite) and E124 (isolated from quartzite) were morphologically similar to the psis sp. . Howeverpsis sp.  and its ttia sp. .Altogether, the Pamirian endolithic communities can be considered to be more heterogeneous than those from the edaphic systems. This is in line with the currently published results of studies of microbial diversity from the cold deserts of Antarctica  and the Despite the use of different markers, the similarities in community structure of endoliths at the higher taxonomic level and alpha-diversity indices were found to be similar to those previously reported in Antarctica ,17,20, hIn the communities analyzed here, the Actinobacteria family was mostly represented by Euzebyaceae. Another abundant family, which was represented in both types of communities, was the Xanthomonadaceae, which belongs to Proteobacteria and is known for its N-fixing ability. Rhizobiaceae, another family with common diazotrophic abilities, was in turn abundant only in the BSCs. The high contribution of these families to the soil-inhabiting bacteria was also reported by other researchers studying samples from Antarctica ,52.Chroococcidiopsis [Gloeocapsopsis [Differences concerning the relative abundance of dominant bacterial phyla identified within the present study, and in previously reported investigations, can be the result of divergent environmental conditions  and geographic isolation. As has been observed in other studies, cyanobacterial communities in the endolithic niche were represented by coccoid package-forming idiopsis ,20,51,53apsopsis , filamenapsopsis . The edaapsopsis . The strChroococcidiopsis sp. and Gloeocapsopsis sp. was confirmed using phylogenetic analysis of the 16S rRNA gene sequences of these cyanobacterial cultures, similarly as for cyanobacterial communities from the Atacama Desert [Wilmottia sp. Its closes relative identified on the basis of the 16S rRNA is Wilmottia murrayi, which belongs to Oscillatoriales and which was reported from Antarctica [The high throughput sequencing technology (next-generation sequencing) provided the opportunity to explore cyanobacterial diversity without applying a culture-dependent approach. However, the isolation and cultivation of cyanobacteria is still an important step to optimize the method of studying this group of microorganisms. In the present study four cultured endolithic cyanobacterial taxa have been characterized following the polyphasic approach for endolithic taxa of cyanobacteria. These cyanobacterial taxa are characterized by high morphological variability, especially those isolated from the most extreme environments. The presence of a Desert . Anothertarctica . The resOur results demonstrated that the hypothesis concerning the separation of the bacteria occurring in the edaphic and lithobiontic niches ,7,12,20 Chroococcidiopsis in loess formation due to its ability to produce the high biomass of extracellular polymeric substances, which was reported recently [Diversity metrics is an informative characteristic of bacterial communities, which characterizes environmental conditions such as the trophic level or water availability . The correcently , is anotThe composition and structure of endolithic communities occurring in the mountain desert of Pamir is mainly shaped by specific microenvironmental factors, which was illustrated by the heterogeneous distribution of taxa within each niche. A link between endolithic and edaphic communities was established, particularly in the most oligotrophic areas, which are characterized by the most severe climatic conditions. While the structure of soil-inhabiting bacterial communities was characteristic for the different subregions of the Eastern Pamir, no patterns associated with geographical distribution were detected for bacterial endolithic communities. The composition and structure of endolithic communities in these geologically divergent areas cannot be associated purely with their geographical location. It seems to be connected more strongly to the specific physicochemical features of different rock types. The cyanobacterial communities occurring at edaphic and endolithic niches in Eastern Pamir share similarities with these from other arid and hyperarid environments; however, the assemblages are also characterized by particular features associated with the unique climatic conditions found in the studied subregions of Pamir.


In order to verify the performance of a graphene-based space radiation detection sensor, the radiation detection principle based on two-dimensional graphene material was analyzed according to the band structure and electric field effect of graphene. The method of space radiation detection based on graphene was studied and then a new type of space radiation sensor samples with small volume, high resolution, and radiation-resistance was formed. Using protons and electrons, the electrical performance of GFET radiation sensor was verified. The designed graphene space radiation detection sensor is expected to be applied in the radiation environment monitoring of the space station and the moon, and can also achieve technological breakthroughs in pulsar navigation and other fields. Although these materials have good energy deposition capacity and large-area preparation is also possible, their electrical properties and charge collection properties are affected by silicon and niobium crystals. In addition, these broadband compound semiconductors are far less mature and advanced than monomass semiconductors in doping, processing, and integrated circuit technology, thus limiting their further application. High-resolution radiation detectors are able to distinguish narrow energy peaks near room temperature or at room temperature, providing new capabilities for radiation detection and measurement in areas such as material characterization, astrophysics, homeland security, and nuclear forensics. Studies have shown that silicon drifting detectors have been used to achieve a significant increase in energy resolution. There are also potential materials for high-resolution radiation detectors, such as high-density, high-charge materials, such as mercury iodide  is a zero-band gap semiconductor material with a conductor belt and a valence band that coincide at the Dirac point. Near the Dirac point, the number of graphene crystals in the k-space unit area is, using a dispersion relationship, expressed as:E = 0, the state density is zero.That is, graphene’s state density and energy at the Dirac point are also linear, and at Under the action of an electric field, Dirac–Fermi can be continuously transformed from an electron (or hole) to a hole (or electron). Far from the Dirac point, graphene has only a single carrier, whose concentration is proportional to the loaded voltage. Because the conductivity is proportional to the carrier concentration, graphene’s resistance value is affected by voltage, as shown in After the rays produce electrons in the detector’s absorption substrate—the cavity pair—under the action of gate voltage, the electron moves towards the graphene detection layer, and the hole moves towards the bottom of the substrate, detecting the number of electrons by bringing the electron drift below the graphene layer . Using g2 insulation layer and a Si semiconductor absorption substrate. Among them, the Si semiconductor absorbs the substrate as the working medium of radiation detection, absorbs the incoming rays and produces an electron–hole pair within the substrate; the SiO2 insulation layer in the graphene detection layer and Si Semiconductors absorb insulation between substrates, preventing electrons produced by radiation rays from being received directly by graphene. Graphene sensitive detection layers are mainly used to sense the electric field formed by radiation-producing electrons.Based on the above analysis, the graphene radiation sensor is designed to consist of three layers: a graphene sensitive detection layer, a SiO2 insulation and eventually gathers below the graphene detection layer. The concentration of graphene carriers is regulated by the electric field by the concentration of the inductors of graphene, which changes the resistance value of graphene by the electric field in which the inductive electrons (holes) are concentrated [Ray incident to detector Si ionization in the substrate produces electrons called cavity pairs, and the number of resulting electron–cavity pairs is proportional to their energy. Load the voltage between the graphene detection layer and the Si semiconductor absorption substrate to form a suitable electric field distribution inside the detector, which directs the electrons (holes) generated by the radiation rays inside the substrate to drift towards the graphene detection layer and is blocked by the SiOentrated . By measentrated , and thuAs can be seen from The penetration path and energy deposition of high-energy electrons are simulated by Monte Carlo simulation, mainly to obtain the penetration depth and energy deposition of incident rays in the substrate medium . Taking Using the CVD method to deposit single-layer polycrystalline graphene film, the test device is prepared, which is shown in 2 insulation layer is 200 μm. The thickness of the electrode with Au is 40 nm. The monolayer graphene sensitive area is 10 μm × 10 μm. In order to detect space particles, semiconductor detection sensitive area can be measured in millimeters, the using of etching technology to etch graphene film into an array distribution of micron-sized graphene units, made of graphene devices. The thickness of Si substrate is 700 μm, and the thickness of the SiO, so that they can be as much as possible ohm contact.In order to characterize the test, the process of gold wire lead welding is required to lead out the electrodes of the micro-devices , so as tThe electrical properties of graphene devices are verified by electron and proton irradiation. The parameters for the electron irradiation test are shown in DSs = 1.0 V, the gate voltage VGSs = 0 V, and the electrical characteristics test are tested by the semiconductor parameter test analyzer Keysight B1500A measured. In order to ensure the comparability of electrical characteristics between the devices, the electrical characteristics test data after irradiation are normalized.Y-axis) after the comparable coordinate processing can be obtained from GS = −50 to 50 V, and the source leak bias VDS is 0.1 V. It can be seen that the current of graphene devices after electronic irradiation decreased significantly, and the numerical treatment was carried out to compare the degree of decline of different irradiated doses. As can be seen from For proton irradiation experiments, the irradiation energy of 40 keV is also set, and the proton irradiation test parameters are shown in 2 media layer.DSs = 0.1 V, gate voltage VGSs = 0 V, and the test time is 60 s. From this diagram, we can see the change of device source leakage current over time, so as to determine the stability of the device. It can be seen from The current stability test curve (I–t curve) for graphene samples before and after electron irradiation is shown in DS = 0.1 V and VDS = 1.0 V, and then normalizing them separately, the relationship between the leakage current and the electron irradiation dose can be obtained, as shown in DSs = 0.1 V and VDSs = 1.0 V, it can be seen that the leakage current at VDSs 0.1 V is more affected by electron irradiation than the leakage current at VDSs = 0.1 V, but the trend of the two is the same.After extracting the leakage current at the source leakage voltages VThe source leakage current stability test curve of graphene samples before and after proton irradiation is shown in DS = 0.1 V and VDS = 1.0 V, the leakage current can be obtained with the change of proton irradiation dose, as shown in After the leakage current is normalized to extract the leakage current at the source leakage voltages VThe application of a graphene field effect transistor (GFET) in collecting radiation-induced charge was verified. The experimental study found that, without any protection, the device electrical and photoelectric performance attenuation is small, showing a strong radiation protection ability. If the device is subsequently given packaged protection, the anti-radiation characteristics of the device will be further enhanced, making the impact of radiation damage smaller. However, in electronic and proton irradiation, it is also found that the electro-transmission characteristics of graphene devices are relatively large, so in practical applications, the device needs to have some package and other protection, so as not to expose the device to high doses of irradiation . The res


Drosophila central nervous system (CNS). Interestingly, we discovered that pharmacological treatments aimed to potentiate GABA neurotransmission were able to revert locomotion deficiencies in TBPH-minus flies, revealing novel mechanisms and therapeutic strategies in ALS.Alterations in the function of the RNA-binding protein TDP-43 are largely associated with the pathogenesis of amyotrophic lateral sclerosis (ALS), a devastating disease of the human motor system that leads to motoneurons degeneration and reduced life expectancy by molecular mechanisms not well known. In our previous work, we found that the expression levels of the glutamic acid decarboxylase enzyme (GAD1), responsible for converting glutamate to γ-aminobutyric acid (GABA), were downregulated in TBPH-null flies and motoneurons derived from ALS patients carrying mutations in TDP-43, suggesting that defects in the regulation of GAD1 may lead to neurodegeneration by affecting neurotransmitter balance. In this study, we observed that TBPH was required for the regulation of GAD1 pre-mRNA splicing and the levels of GABA in the  TDP-43 is a protein involved in several aspects of RNA metabolism including pre-mRNA splicing, mRNA transport and micro RNA maturation 6. A breakthrough link with neurodegenerative diseases came in 2006, when TDP-43 was identified as the main component of the ubiquitinated cytoplasmic inclusions in ALS and frontotemporal lobar degeneration (FTLD) 9. TDP-43 pathology is currently described in a large proportion of cases of Alzheimer’s disease as well as Parkinson’s and Huntington’s disease 14. Attentive studies aimed to understand the normal function of TDP-43 and its participation in the mechanisms of neurodegeneration have, therefore, became critical to establish the metabolic pathways implicated in TDP-43-mediated neuronal toxicity. In this direction we have previously indicated that TDP-43 is required to regulate the synaptic levels of GAD67, the enzyme responsible for converting glutamate to γ-aminobutyric acid (GABA), suggesting that modifications in the glutamate/GABA neurotransmitter balance may affect neuronal survival in TDP-43 perturbed brains 15. In this direction, evidences of the involvement of glutamate in the pathogenesis of ALS disease were already suggested by several studies 18. However, treatments aimed to prevent glutamate mediated excitotoxicity have failed to correct the clinical symptoms of the disease, revealing that different mechanisms might be at work besides the excessive availability of glutamate. In support of this hypothesis, it has been reported that GABA levels are reduced in motor cortex of patients with ALS and demonstrated that TDP-43 overexpression increased GAD67 protein levels and GABA release in mouse forebrain 22, implying that the synaptic transmission mediated by GABA might be affected or/and may have a role in TDP-43 defective brains. In this study we investigated the mechanisms by which TDP-43 regulates the cytoplasmic levels of GAD1 and determined the role of GABA neurotransmission in TDP-43 pathology using Drosophila.A common characteristic shared by several neurodegenerative diseases is the dysfunction of the RNA-binding protein TDP-43, a member of the heterogenous nuclear ribonucleoproteins (hnRNPs) family 15. In order to address this question, and considering that TBPH is involved in the regulation of different aspects of RNA metabolism, we decided to investigate whether GAD1 RNA splicing was affected in TBPH-minus alleles . To this purpose, we designed a set of primers specific to discriminate GAD1 pre-mRNA and another one specific for mRNA . Thus, S2 cells co-transfected with an RNAi against TBPH showed a strong reduction in the expression of the EGFP protein compared to control cells treated with an RNAi against luciferase in western blot assays  A type receptor (RDL), the ligand-gated chloride channel (LCCH3), the GABAB type receptor 1, 2 and 3  were expressed, either alone or together with an RNAi against TBPH, under the neuronal driver elav-GAL4. As a result, we found that the suppression of the GABA receptors strongly enhanced the motility problems present in TBPH-defective flies compared to control insects expressing the RNAi against the GABA receptors alone  was added to the fly food during larvae development and we found that the administration of this compound was able to consistently improve the peristaltic movements of the TBPH-minus third-instar larvae (L3) compared to untreated mutants or wild-type controls Fig. a.Figure Δ23, elav-GAL4/ + ; TBPH-RNAi/ +) were sufficient to recover motility , this showed a significative rescue of L3 larvae motility in TBPH hypomorphic background-null alleles compared to controls  mouse model 25, in which the glutamatergic neuronal hyperexcitability was associated to a decreased GABAergic intracortical inhibition 26. On a different ALS mouse model, the wobbler mice 27, similar evidences were described including a reduction in vesicular GABA transport followed by a decreased GABAergic inhibition 28. Suitably, alterations in GABA neurotransmission were described in patients suffering from Alzheimer’s disease 29, Parkinson’s disease 30 and related neurodegenerative process in addition to ALS 31. Nevertheless, despite the evidences indicated above, the role of GABA and others inhibitory neurotransmitters balance in TDP-43 pathology was not completely clarified. In that respect, our data revealed that TBPH, the TDP-43 conserved protein in Drosophila, plays an important role in maintaining the equilibrium between neuroexcitatory and inhibitory signals through the regulation of GAD1, the enzyme responsible for the synthesis of GABA after the cleavage and processing of glutamate. On that point, we found that TBPH has an important role in the modulation of GAD1 mRNA splicing. Thus, we observed that a reduction of TBPH promoted the accumulation of GAD1 pre-mRNA transcripts with the subsequent reduction in the processing and generation of mature GAD1 mRNA and protein. Regarding the molecular mechanisms, notwithstanding the presence of putative binding sites for TBPH in the 5’UTR region of GAD1 mRNA, we did not find a direct binding between TBPH and GAD1 mRNA 15. Successively, we observed that the overexpression of TBPH was not sufficient to modify the pre-mRNA processing of GAD1 either  significantly contribute to the pathological phenotypes described in TBPH loss of function alleles. In that respect, we observed that the pharmacological potentiation of GABA signaling with nipecotic acid, an inhibitor of GABA uptake, was able to significantly revert the locomotor defects observed in TBPH-null flies. Interestingly, our results are in line with other evidences obtained from different ALS models, Boussicault et al. 2020 demonstrated that GABA agonists treatment synergistically improved the phenotype in primary cultures of motoneurons derived from SOD1 G93A rat embryos 34. On the other hand, clinical trials using GABA agonists to treat ALS patients have not yet yielded significant results suggesting that the modulation of GABA neurotransmission alone may not be sufficient to overcome the complete symptoms of the disease 35. More sophisticated therapies, perhaps combining GABAergic with anti-glutamatergic approaches, might be required to re-stablish the neurotransmitter balance in TDP-43 affected brains. In support of this hypothesis, gene-based therapies using GAD1 to modulate neuronal signaling are being used to treat patients with Parkinson’s disease and similar approaches could be evaluated in patients with ALS 37.Defect in the neuronal handle of the excessive formation of glutamate, has been long implicated in the mechanisms of neurotoxicity behind ALS. However, growing evidences suggest that the glutamate-induced excitotoxicity hypothesis, alone, is not sufficient to explain the hyperexcitability of the motoneurons observed in ALS. In effect, one of the few approved compounds to treat ALS, riluzole, besides its anti-glutamate action directly interact with GABA receptors, signifying that the activation of inhibitory neurotransmission may also play a role in the disease. In this direction, a reduced GABA levels in the motor cortex of ALS patients were previously describe Altogether, our results reveal a novel molecular mechanism behind TDP-43-derived pathologies and put forward novel therapeutic strategies aimed to potentiate inhibitory signaling or balancing the levels of neurotransmitters may succeed to control motoneurons hyperexcitability in ALS affected individuals.1118—OregonR—w;tbphΔ23/CyOGFP —w;tbphΔ142/CyOGFP —w;elav-GAL4/CyOGFP—w,UAS-Dicer2;elav-GAL4/CyOGFP—w;siRNA-UAS-GFP —w;UAS-GAD1/TM3,Sb (gifted from Dr. Andreas Prokop)—w;UAS-TBPH—w;UAS-mCD8::GFP/CyO—w;UAS-TBPH-RNAi/TM6B —siRNA-GABAA receptor, resistant to dieldrin —siRNA Ligand Gated Chloride Channel —siRNA Glycine like receptor —siRNA Vesicular GABA Transporter —siRNA-GABAB Receptor Type 1 —siRNA-GABAB receptor Type 2 —siRNA-GABAB receptor Type 3 .The fly genotypes used for the experiments are indicated hereafter: wFreshly eclosed flies were transferred in new food vials and let to adapt for 3 to 4 days. A female-male ratio of 1:1 was maintained. After this period, they were moved, without anesthesia, to 15 ml glass cylinders, tapped to the bottom and let climb taking advantage of their natural drive for negative geotaxis. The number of flies that reached the top of the tube in 15 s was counted, and converted in percentage.38. Briefly, for whole larval brain staining, previously selected larvae were dissected on Sylgard plates in Phosphate Buffer (PB), brains were removed and fixed 20 min in 4% formaldehyde in Phosphate Buffer with 0.3% Triton X100 (PBT), blocked in 5% Normal Goat Serum (NGS), labelled with primary and secondary antibodies and mounted on microscope slides in Slow Fade . Brain images were acquired on 20 × at a 0.6-fold magnification on a LSM 880 Zeiss confocal microscope and then analyzed using ImageJ. Z-stacking was performed and the ratio of GABA/Elav Max Intensity was calculated. Primary antibodies concentration: anti-Elav , anti-GABA . Secondary antibodies concentration: Alexa Fluor 488 , Alexa Fluor 555 .Larvae were selected and dissected as previously described in Drosophila TBPH (5’-GGAAGACCACAGAGGAGAGC-3’), as control siRNA for luciferase was used . Immediately before transfection 2 × 106 cells were seeded in 6-well plates in 1.4 ml of medium containing 10% fetal serum. 2 µg of each siRNA, were added to 91 µl of Opti-MEM I reduced serum medium , incubated 5 min at room temperature and subsequently 6 µl of HiPerfect Transfection Reagent were added. The silencing procedure was performed again after 24 h. Plasmid containing the Gad1 mini-gene and GAL4 were co-transfected (0.3 µg each) at 24 h together with the second siRNA dose. Cells were analyzed after 72 h of the initial treatment.S2 cells were cultured in Insect-Xpress medium (Lonza) supplemented with 10% fetal bovine serum and 1X antibiotic–antimycotic solution . RNA interference was achieved using HiPerfect Transfection Reagent  and siRNA specific for A mini-gene containing the 5’ UTR region of Gad1 spanning from exon1 to exon2 (ref isoform FBtr0073276) in frame with a reporter EGFP has been cloned in pUAST attB plasmid. The minigene was co-transfected with p-actin-GAL4 in S2 cells. The EGFP expression was analyzed in S2 cells treated with siRNAs against TDP-43 or luciferase.Adult heads were mechanically squeezed to proceed with RNA extraction, using RNeasy Microarray tissue kit (#73304 Qiagen) and treated with Turbo DNA-free kit (#AM1907 Ambion). Retro-transcription was performed using oligo-dT primers and SuperScript III First-Strand Synthesis (#18080093 Invitrogen). Gene specific primers were designed for amplification:5’GCCAAACTCCGCATTCCATTT3’ and 5’ACCGAAGGCCGTGGGTCCTCG3’;Gad1(intronic set): 5’TGATCCTTGAACCGGAGTGC3’ and 5’ACCATCAGCGTTCCCTTCTG3’;Gad1(exon/exon set): 5’CCATCGGTATCTATGGTCTGGA3’ and 5’CATCGTATTTCTGCTGGAACCA3’.Rpl11 T equation and then normalized on control genotype.The quantification was calculated according the ΔΔC23 and anti -tubulin DM1A . Secondary antibodies concentration: anti-rabbit HRP conjugated , anti-mouse HRP conjugated . For detection, SuperSignal West Femto Maximum Sensitivity Substrate Kit  was used. Quantification was performed by Alliance software, after acquisition with UVItec CAMBRIDGE Alliance.S2 cells were lysed in lysis buffer ) and after protein quantification of lysates by Qbit , samples were separated on NuPAGE 4–12% Bis–Tris precast gels (Thermo Fisher Scientific) and transfer to 0.22 µm nitrocellulose membranes (#NBA083C Whatman Protran). Membranes were blocked in 5% non-fat dry milk in Tris Buffered Saline with 0.1% Tween-20 (TBS-T). Primary antibodies were used with the following concentrations: anti-GFP , anti-TBPH  and the two-way ANOVA test Fig. .Supplementary Figures.


Staphylococcus aureus (SA4-149), Staphylococcus epidermidis (SEP7602), Streptococcus pyogenes (SPY165), Streptococcus agalactiae (SAG146), and Enterococcus faecium (EF897) previously characterized.The concentration of quinolone uptake was estimated by agar disc-diffusion bioassay. Furthermore, we determined the inhibitory concentrations 50 (IC50) of OZN, MOX, LVX, and CIP against type II topoisomerases from S. aureus.The accumulation of OZN inside the bacterial cell was superior in comparison to MOX, LVX, and CIP in all tested species. The accumulation of OZN inside the bacterial cell was superior in comparison to MOX, LVX, and CIP in all tested species. The rapid penetration of OZN into the cell was reflected during the first minute of exposure with antibiotic values between 190 and 447 ng/mg (dry weight) of bacteria in all strains. Moreover, OZN showed the greatest inhibitory activity among the quinolones tested for both DNA gyrase and topoisomerase IV isolated from S. aureus with IC50 values of 10 and 0.5 mg/L, respectively. OZN intracellular concentration was significantly higher than that of MOX, LVX and CIP. All of these features may explain the higher in vitro activity of OZN compared to the other tested quinolones.The big problem of antimicrobial resistance is that it requires great efforts in the design of improved drugs which can quickly reach their target of action. Studies of antibiotic uptake and interaction with their target it is a key factor in this important challenge. We investigated the accumulation of ozenoxacin (OZN), moxifloxacin (MOX), levofloxacin (LVX), and ciprofloxacin (CIP) into the bacterial cells of 5 species, including  A long list of compounds with antagonistic activity against bacteria have been described by various researchers worldwide . Many ofIn this sense, most of the existing techniques for determining the cellular accumulation of compounds are based on the detection of fluorescence ,6. SpeciMoreover, techniques based on LC-MS described by Zhou et al., 2015  could beStaphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) . Then, 25 µL of the aqueous phase of each sample was analyzed on 1% agarose gels for 4 h at 80 V in 1XTAE  and visualized after staining with SYBR® Gold Nucleic Acid stain  under UV light. For each analysis, a negative control that contained the buffer tampon and plasmid pBR322/kinetoplast, and a positive control that contained 1 U of enzyme (gyrase or topo IV) were used, and finally, four reactions with different concentrations of quinolones were analyzed.The enzymatic assay was carried using commercial topoisomerase type II as previously described by Alt et al.  with som50) for each antibiotic. The IC50 was defined as the concentration causing 50% inhibition of the supercoiling or the decatenation reaction, as seen with the drug-free controls.The analysis of gel electrophoresis bands was performed using G:BOX software  to determine the inhibitory concentration 50 (ICS. aureus and S. pyogenes, which are causal agents of impetigo. Furthermore, this fast penetration of OZN allows for a quick interaction with the targets of action, inhibiting DNA gyrase supercoiling activity and topoisomerase IV decatenation simultaneously. All of these features may explain the higher in vitro activity of OZN compared to the other tested quinolones.The strong inhibitory activity of ozenoxacin at low concentrations might be explained by its rapid penetration of the bacterial cell in the first minute after exposure, reaching high intrabacterial concentrations compared with other quinolones in all studied microorganisms, among them


This study analyzed the mechanical and fracture behavior of graphene/copper (Cu) composites with different Cu thicknesses by using molecular dynamics (MD) and representative volume element (RVE) analysis. Three graphene/Cu composite analytical models were classified as 4.8, 9.8, and 14.3 nm according to Cu thicknesses. Using MD analysis, zigzag-, armchair-, and z (thickness)-direction tensile analyses were performed for each model to analyze the effect of Cu thickness variation on graphene/Cu composite strength and delamination fracture. In the RVE analysis, the mechanical characteristics of the interface between graphene and Cu were evaluated by setting the volume fraction to 1.39, 2.04, and 4.16% of the graphene/Cu composite model, classified according to the Cu thickness. From their obtained results, whether the graphene bond is maintained has the greatest effect on the strength of graphene/Cu composites, regardless of the Cu thickness. Additionally, graphene/Cu composites are more vulnerable to armchair direction tensile forces with fracture strengths of 14.7, 8.9, and 8.2 GPa depending on the Cu thickness. The results of this study will contribute to the development of guidelines and performance evaluation standards for graphene/Cu composites. Graphene is highly flexible and does not lose its intrinsic electrical conductivity when its area increases by more than 10% or it is bent. In addition, graphene has a 0.5–1 TPa elastic modulus [Graphene, a structure with a hexagonal arrangement of carbon (C) atoms, is a thin and light nanomaterial with a thickness of 0.14 nm and a density of 0.77 mg/m modulus . As suchTo produce graphene on an industrial scale, it is necessary to consider a large area, high quality, and cost effectiveness. For instance, Zhuo et al.  producedNevertheless, mass-producing graphene for commercialization is still difficult. The acquisition of high-quality large-area graphene for commercialization inevitably poses the risk of defects in the manufacturing process. To overcome this limitation, previous studies have continued the efforts to utilize graphene and metals as composite materials (composites). Since graphene has a large specific surface area and is composed of small atoms, using it in graphene/metal composites can facilitate graphene manufacturing and enhance existing metal materials with small volumes, which satisfies the strength and weight requirements and improves important mechanical properties such as tensile strength and elastic modulus ,7.In related studies, Kim et al.  revealedIn particular, efforts are being made to composite Cu, which is widely used in semiconductor wiring and electronic devices, with graphene. Cu is a material with excellent electrical properties, and when used in combination with graphene, it is possible to add the excellent properties of graphene to the properties of Cu.In other related studies, Kim et al.  developeNevertheless, previous studies have focused on the strength improvement effect or electrical/thermal efficiency problems in graphene and Cu composites, and the usage specifications and performance of graphene/Cu composites for mass production or commercialization have not been fully researched. Furthermore, fracture characteristics such as interface delamination, which inevitably occurs when combining graphene and Cu, have not been elaborated on.Therefore, according to these needs, this study evaluated the mechanical properties and delamination characteristics of graphene/Cu composite fractures according to two analytical methods. First, since the excellent properties of graphene result from its atomic structure, the MD approach, which is a suitable method for calculating intrinsic fracture phenomena that considers the atomic bonds of materials, was performed to evaluate the characteristics of the graphene/Cu composite interface.Subsequently, representative volume element (RVE) analysis was performed to evaluate the mechanical properties associated with the interface between graphene and Cu, which extended from the microscopic dimension to the macroscopic dimension. RVE analysis is a technique that evaluates the properties of composites at a microscopic scale. This technique is independent of MD analysis and is extended to the microscopic scale, which is the scale at which graphene/Cu composites are used. The derivation of material properties at the macroscopic scale and the close examination of the characteristics of the interface between materials are possible by performing a distribution shape analysis of the mixed constituents in composites. As such, this study will be useful in the development of guidelines and performance evaluation criteria for graphene/Cu composites, because it is performed as an evaluation of graphene/Cu composites according to Cu thickness by controlling the thickness of Cu that is easy to manufacture.Carbon atoms in graphene arrange in either zigzag or armchair configurations. This means that even if the same tensile force is applied to graphene, crack propagation may vary depending on the direction of the tensile force. Therefore, MD is required to estimate the effects of the graphene atomic arrangement.The MD technique is known to be the most suitable method for computing changes in the dynamic properties of nanomaterials. Nanomaterials such as graphene have large specific surface areas; therefore, the phenomena that occur at interfaces have a significant impact on their characteristics. An MD analysis allows us to account for the structural features associated with the atomic arrangement of graphene, calculate the interactions between the graphene and Cu molecules as tensile forces are loaded, analyze the mechanical behaviors, and obtain the strength and strain values. In this study, the large-scale atomic/molecular massively parallel simulator (LAMMPS)  was usedIn general, LAMMPS analysis proceeds in three stages. The first step involves the creation of an initial model that consists of the number of atoms that shapes the analytical model. To produce composites, each of the two materials must be modeled before the composites are modeled. In this paper, after modeling graphene and Cu separately, two models were used for graphene/Cu composites, and three new models were produced to evaluate different Cu thicknesses. The Cu thickness was modeled as 5, 10, or 15 nm in the graphene/Cu composites in accordance with previous studies in the semiconductor field that used <10 nm graphene in processing ,17.Moreover, the potential of each atom was determined, as this is the most appropriate method to calculate the interactions between atoms. In this study, Tersoff  potentiaThe second step involves an equilibrium stage, in which Newtonian equations are used to interpret the process (equilibrium phase) in which the position and speed of the atoms that make up the molecules are independent of changes over time. It is necessary to obtain only the desired properties, with the synthesized interatomic bonds acting as compounds. The concept of a computer simulating the interaction between atoms is called an ensemble, and ensembles should be determined in the equilibrium phase.The last step involves calculating the physical quantities. Equilibrium graphene/Cu composite models are subjected to tensile analysis to evaluate their failure and strength under various conditions. A tensile analysis should define the tensile direction and velocity. Specific inputs and interpretation conditions for each step are described in Table 1 of The physical properties of composites depend on the size, volume fraction, shape and mixed structure of the component materials; thus, an evaluation of the RVE, which models microcomposites, is important . The RVEPBCs are a concept used in both RVE analysis and MD. If the simulation box is periodic, then atoms interact across the boundary, and they can exit from one end of the box and enter in the other end again. As a result, since the total number of molecules in the box remains constant, it can be homogenized, as the meaning of the boundary disappears within the system as a whole.PBCs are applied evenly according to the characteristics and shape of the composites. Specifically, for each interface, the boundary conditions are applied by binding the top and bottom surfaces and the left and right surfaces. This is the governing equation for the PBCs in Equation (1).In Equation (1), The governing equation is Equation (2). tion (4) .(3)σ11σIn the modeling phase, the analytical model is divided into three separate models according to the thickness of Cu, as shown in The thicknesses used in models A, B and C were 4.8, 9.8 and 14.3 nm, respectively. The thickness of Cu was determined by referring to studies from the semiconductor field in which the product thickness was less than 10 nm when graphene was used. Subsequently, the specific condition of the atomic system in the equilibrium phase, the ensemble, was used to produce an NVT ensemble. NVT ensembles are suitable ensembles that can be used in tensile analysis because they reduce the incidence of errors in mechanical property predictions by considering the number of atoms (N), volume (V), and temperature (T). In the tensile analysis step for each axis, the boundary condition was set to 0.6 nm at both ends of the axis. For graphene, there were three types of tensile forces applied to each axis , and the tensile speed was 0.017 nm/ps. The x-axis is the zigzag direction, and the y-axis is the armchair direction. The z-axis is in the direction of the thickness of the structure. The analytical cases were distinguished based on the load direction. Cracks exist in the zigzag and armchair directions which are feature of hexagonal graphene. Under these conditions, the characteristics of both the armchair direction and the zigzag direction of graphene were determined. The following were used to describe the conditions under which bonds were broken: when the stress approached zero; when the hexagonal arrangement inherent to graphene was broken; and when Cu was completely fractured.The RVE analytical model is composed of Cu and graphene, as illustrated in The RVE model comprises three separate models, and the volume fraction of graphene in each model was specified as 1.39, 2.04, or 4.16%. These criteria result from calculating the volume fraction of graphene and Cu in the three models by using MD. The properties of graphene and Cu are shown in The 1.39% value results from calculating the volume fraction of model A with MD by using the largest Cu thickness, where the 2.04% value is the volume fraction of model B calculated with MD, and the 4.16% value is the volume fraction of model C calculated with MD by using the smallest Cu thickness. The boundary condition for each RVE analytical model includes six analytical cases in which the center point of the RVE model is fixed (Ux = Uy = Uz = 0), and the strain in each direction , the maximum stress increases to 182 GPa.Additionally, the stress levels and range in Cu increased as the volume fraction of graphene increased. Since all three analytical models had the same applied strain magnitude, this result means that as the volume fraction of graphene under the same loading conditions increases, the stress level in the graphene/Cu composites also increases.The intraparticle stress variations in graphene are illustrated at the bottom of From the left, the volume fraction of graphene increases from 1.39% to 2.04% and then to 4.16%. The overall stress variations are similar to those of the x-axis analysis. That is, graphene is under higher stress than Cu, and the stress level increases as the volume fraction of graphene increases.For all of the analytical models, a maximum stress of 170 GPa is observed when the volume fraction of graphene is 1.39%. When the volume fraction of graphene is 2.04%, the maximum stress is 173 GPa, and when the volume fraction of graphene is at its largest (at 4.16%), the maximum stress increases to 182 GPa. The intraparticle stress variations in graphene are similar to those of the x-axis analysis. When a tensile force was applied along the y-axis, the highest stresses appeared in the graphene at the top and bottom of the diagonal of the y-axis, and a low stress variation was observed along the rotational direction of the y-axis. These results indicate that the tensile force applied along the y-axis of the graphene/Cu composites causes greater deformation along the diagonal of the load direction than at the center of the graphene.For all of the analytical models, a maximum stress of 170 GPa is observed when the volume fraction of graphene is 1.39%. When the volume fraction of graphene is 2.04%, the maximum stress is 173 GPa, and when the volume fraction of graphene is the largest (at 4.16%), the maximum stress increases to 182 GPa. These results are the same as those observed in the y-axis tensile analysis. The stress variations in graphene were also found to be the same as those observed in the x-axis and y-axis tensile analyses. The highest stresses appeared in the graphene at the top and bottom of the diagonal of the z-axis, and a low stress variation was observed along the rotational direction of the z-axis. These results indicate that the tensile force applied along the z-axis of the graphene/Cu composites causes greater deformation along the diagonal of the load direction than at the center of graphene. The same results were also found for the As with previous results, increasing the volume fraction of graphene only increases the stress value, and all other results show the same trend. Therefore, representatively, the As shown in Equations (2)–(4)  were appIt was calculated that the RVE model with a 1.39% volume fraction of graphene had an elastic modulus of approximately 112 GPa and a Poisson’s ratio of 0.34. This result is attributed to an increase of only 2 GPa in the elastic modulus of Cu. However, when the volume fraction of graphene increased to 4.16%, the elastic modulus increased to approximately 118 GPa, and the Poisson’s ratio decreased to 0.33.These results imply that an increase in the volume fraction of graphene increases the elastic modulus of the Cu/graphene composites and decreases the Poisson’s ratio. The physical properties calculated and described above are properties that consider the microscopic constituents of the composite material containing graphene, the volume fraction, and the mixed structure of the constituent materials. These properties can be used for a macroscopic structural analysis.In this study, uniaxial tensile analyses were conducted considering three different directions to estimate the effects of Cu thickness on structural fracture and stress behavior in graphene/Cu composites. The following conclusions were obtained.In the MD analysis results for graphene/Cu composites, the strength performance of the graphene/Cu composites is influenced by whether the graphene maintains its bonds. The strength of the graphene/Cu composites does not increase if the Cu thickness increases. Rather, an increase in Cu thickness in the same tensile direction reduces the strength performance of the graphene/Cu composites.Additionally, graphene/Cu composites are more vulnerable to armchair-direction tensile forces than zigzag-direction tensile forces. In graphene/Cu composites, it is necessary to consider the direction of graphene to prevent sudden fracture after delamination.In the RVE analysis results for the graphene/Cu composites, a large stress occurred in graphene, which resulted in a large stress difference between graphene and Cu. This means that the interface of graphene/Cu composites is most vulnerable to external loads. The difference according to the volume fraction change was that when the volume fraction of graphene increased, the stress distribution of Cu also increased.In the RVE analysis results for graphene where the stress is most concentrated, even within graphene, various stress distributions were observed. These results disprove the necessity of RVE multiscale analysis for graphene/Cu composites. In this study, it was found that higher stress appeared at the interface than at the center of graphene.Further work should be performed with the aim of evaluating graphene/Cu composites that laminated multi-layer graphene rather than single-layer graphene. This further work will validate the usage specifications and performance of graphene/Cu composites in practical applications such as semiconductor wiring and electronic devices.


The key performance index for the polarization independent modulator is polarization-sensitivity loss (PSL). The waveguide of our device just supports basic TE and TM modes, and the PSL between two modes is of < 0.24 dB. The model can offer extinction ratio (ER) more than 16 dB and insertion loss less than 1 dB. The operation spectrum ranges from 2 to 2.4 μm with optical bandwidth of 400 nm. The 3 dB modulation bandwidth is as high as 136 GHz based on theoretical calculation.A polarization-insensitive graphene-based mid-infrared optical modulator is presented that comprised SiO Near-infrared wavelength optical fiber communication networks are becoming the core of the whole telecommunication networks. However, the mid-infrared is also an important waveband for the application of electro-optic device in military and civil fields, such as infrared countermeasure, chemical sensing, infrared guidance, environmental monitoring, space communication, etc. In addition, mid-infrared integrated electro-optic devices, such as photodetectors and modulators, also are developed to expand the 1.55 μm communication window.23Sb7S70-on-graphene structure, which opened the field of graphene-based mid-infrared modulator.In recent years, 2D functional electro-optic materials, such as graphene –4, chalcGraphene as electro-optic material, we also need to consider one of the most important characteristics of anisotropic dielectric , which h23Sb7S70 glass strip which is embedded in SiO2 cladding as waveguide core. In the Ge23Sb7S70 waveguide, two graphene layers are U (semiellipse)-type distribution and are insulated by Ge23Sb7S70 glass. Since the graphene layer is U-type distribution, both TE and TM modes can strongly interact with graphene. By proper choosing structure parameters, we can well overcome the polarization dependence. Using the finite element method (FEM), we analyzed the effective mode index (EMI) and absorption coefficient (α) of the U-structure device. The result shows that the real parts of EMI for TE (Nte) and TM (Ntm) modes have the same fluctuations (with constant difference) in different chemical potential (μc), and the imaginary parts of both TE and TM modes have almost identical fluctuations and wavelength independent in a wide spectrum. By proper choosing of switching points for “ON” and “OFF” states, for both TE and TM modes, the modulation depth is more than 16 dB, the operation wavelength spectrum is 2–2.4 μm, the PSL is less than 0.24 dB, and the theoretical 3 dB modulation bandwidth is as high as 136 GHz.In this work, we present a new structure of graphene-based mid-infrared polarization-independent electro-optic modulator, which has the advantages of large modulation bandwidth and wide spectrum of polarization insensitivity. We used the SOI structure and a Ge23Sb7S70 glass ranges from 2 to 10 μm . Th. ThR is 100 Ω/μm  and Rs =100 Ω/μm  were useThe above simulations are based on the semiellipse layout with Ra = 0.35 μm and Rb = 0.565 μm. However, in fabrication, this exact radius size cannot always be guaranteed. Therefore, we have also investigated the fabrication tolerance Fig. . When RaIn conclusion, we presented a concept of a broadband polarization-independent graphene-based mid-infrared electro-absorption optical modulator. In our structure, a U-structure double-layer graphene is placed in chalcogenide glass waveguide. Under different graphene chemical potentials, different wavelengths and different short radius lengths, the graphene-induced EMI variations for both TE and TM modes are investigated. The results show that TE and TM modes have almost identical absorption coefficient variation in the mid-infrared 2–2.4 μm, which fulfills the requirement of polarization-independent modulation. Based on this structure, the modulator with a length of 200 μm has a modulation depth more than 16 dB. The modulation depth difference between the two modes is 0.24 dB, and the theoretical modulation bandwidth of the device is as high as 136 GHz. We believe that this mid-infrared polarization-independent graphene-based electro-optic modulator will further promote the study of the graphene-based modulator in the middle-infrared bands.


Based on the graphene floating gate, a tunable terahertz metamaterial absorber is proposed. Compared with the traditional graphene–dielectric–metal absorber, our absorber has the property of being non-volatile and capacity for anti-interference. Using the finite element method, the paper investigates the absorption spectra, the electric field energy distribution, the tunability and the physical mechanism. In addition, we also analyse the influence of geometry, polarization and incident angles on the absorption. Simulation results show that the bandwidth of the absorption above 90% can reach up to 2.597 THz at the center frequency of 3.970 THz, and the maximum absorption can be tuned continuously from 14.405% to 99.864% by controlling the Fermi level from 0 eV to 0.8 eV. Meanwhile, the proposed absorber has the advantages of polarization insensitivity and a wide angle, and has potential applications in imaging, sensing and photoelectric detection. Terahertz (THz) waves have proven to be promising applications in the areas of imaging , communiGraphene possesses many unique electronic and optical properties, which can be applied in solar cells  and otheTo improve the anti-interference ability of the absorbers, we designed a non-volatile tunable THz MMA by using the graphene floating gate. In the off condition of external bias voltage, the absorption of the absorber can still maintain stability. Compared with the traditional tunable terahertz absorber, our absorber has the property of being non-volatile and capacity for anti-interference. Furthermore, the results indicate that the frequency range of absorption above 90% is 2.671 THz to 5.268 THz, and the tuning depth of maximum absorption is 85.575%. Meanwhile, the proposed absorber has the advantages of polarization insensitivity and a wide angle.2), isolation layer  and upper conductive layer (p-type Si), where the graphene composite layer is made up of silicon dioxide embedded in a graphene block. The conductivity of gold is σ = 4.09 × 107 S/m [2 and Al2O3 are ε = 3.80 [ε = 9.39 [A(ω) = 1 − R(ω) = 1 − |S11|2, where R(ω) is reflectivity, S11 is reflection coefficient. 107 S/m . The disε = 3.80  and ε = ε = 9.39 : A(ω) = The graphene floating gate consists of the top five layers of the absorber, as shown in The absorption spectrum is presented in To grasp the physical mechanism of the absorber, the electric field distributions of the graphene composite layer at 2.995 THz and 4.808 THz are calculated, as shown in L, the bandwidth of the absorber broadens monotonously and the maximum absorptivity increases gradually. That is because the bigger the side length L is, the farther the spacing between two resonance frequencies of the transverse and longitudinal plasmon resonances is. Meanwhile, the ability to localize the electric field becomes stronger as the side length L increases.According to the above analysis, the absorbing performance of the absorber is closely related to the graphene composite layer. So, we compute the influence of the graphene geometries on the absorption spectra, as shown in 2 of the dielectric layer for the proposed absorber. So, we calculated the influence of the thickness on the absorption spectra, as shown in 2, the absorption firstly increases and then decreases, due to the realization of a good impedance match between the absorber and the free space near h2 = 9 μm. When h2 deviates from 9 μm, the impedance mismatch results in a decrease in absorption.In a perfect absorber design, the impedance matching plays an important role, which mainly depends on the thickness hEf and charge density Ef in Ef from 0 to 0.8 eV. When the Fermi level increases to 0.5 eV, the absorptivity is over 80%. Furthermore, the electric field distributions of the graphene composite layer at the center frequency of 3.970 THz for different Fermi levels are shown in Ef ≥ 0.5 eV, the increase in the absorption slows down and the electric field has a slight change. Moreover, as the fE changes from 0 eV to 0.7 eV, the electric field energy is continuously concentrated. The reason is that the higher the fE, the lower the intrinsic loss of graphene [The tunability of the absorber is realized by graphene, because the Fermi level of the graphene can be adjusted by changing the applied voltage. Graphene in a floating gate can capture the tunneled electrons under the positive applied voltage, which increases the charge density. On the contrary, graphene, under the reverse applied voltage, can release electrons, leading to a decrease in its charge density. The relationship between Fermi level  follows ,43: Ef≈μgraphene . It is hIn addition, we also investigate the sensitivity to polarization and the robustness of oblique incidence for the proposed absorber, and its corresponding absorption spectra are shown in In this paper, we propose a broadband, tunable, non-volatile, polarization-insensitive and wide-angle THz MMA based on a graphene floating gate. The absorption of the absorber can be dynamically tuned by changing the Fermi level of graphene and the depth of the tuning reaches up to 85.575%. More importantly, it can maintain a stable absorption performance even if the external bias voltage is disconnected. The proposed absorber shows potential applications in terahertz detecting, imaging, sensing and stealth areas.


This study focuses on the contact regions among neighboring nanoparticles in polymer graphene nanocomposites by the extension of nanosheets. The resistance of graphene and the contact zones represent the total resistance of the prolonged nanosheets. Furthermore, the graphene size, interphase depth, and tunneling distance express the effective volume portion of graphene, while the onset of percolation affects the fraction of percolated nanosheets. Finally, a model is developed to investigate the conductivity of the samples using the graphene size, interphase depth, and tunneling size. In addition to the roles played by certain factors in conductivity, the experimental conductivity data for several samples confirm the conductivity predictions. Generally, the polymer sheet in tunnels determines the total resistance of the extended nanosheets because graphene ordinarily exhibits negligible resistance. In addition, a large tunnel positively accelerates the onset of percolation, but increases the tunneling resistance and attenuates the conductivity of the nanocomposite. Further, a thicker interphase and lower percolation threshold promote the conductivity of the system. The developed model can be applied to optimize the biosensors detecting the breast cancer cells. However, the dispersion of graphene and the formation of conductive networks in thermoplastic polymer matrices are easier than those of rubbers, owing to the complexity of network creation in cross-linked rubber matrices. Certain studies have shown that graphene nanocomposites exhibit a relatively low percolation threshold and more optimized electrical conductivity than CNT23. Generally, the high surface energy of graphene and their strong interactions attenuate their uniform dispersal in the polymer medium28.Graphene has the ability to combine the unusual electrical conductivity of carbon nanotubes (CNT) and excellent barrier properties of layered clays with significant mechanical stiffness30. Many models have been developed to assume the effects of various variables, such as polymer-filler interfacial energy (affecting dispersion level), tunneling effect, agglomeration, and waviness on the conductivity of polymer nanocomposites37. These models can offer guidelines for determining effective parameters on the conductivity of nanocomposites. Numerous studies have used the conventional power-law model to predict the percolation onset and an exponent using the tested conductivity for graphene-based nanocomposites40; however, this model disregards innovative features such as tunnels and interphase districts.The conductivity of nanocomposites is commonly governed by the concentration, dimensions, conductivity, and dispersion features of nanoparticles44. This implies that even a short distance between nanoparticles can form conductive paths to promote conductivity. Accordingly, the onset of percolation in the nanocomposites does not depend solely on the dimensions of nanoparticles, because it can be changed by the tunneling distance. The filler dimensions, contact area, tunneling distance, and polymer matrix affect the contact resistance45. Furthermore, the tunneling resistance was found to increase rapidly as the thickness of insulating layer between the two nanoparticles increases46.The tunneling effect governs the electrical conductivity of graphene-filled nanocomposites because electrons can be transported between adjacent nanosheets through a tunneling mechanism, even when they are not physically joined51. The effects of the interphase depth and toughness on the potency of polymer nanocomposites have been studied previously55. Interestingly, the interphase district can create networks in the nanocomposite, which shifts the onset of percolation and enlarges the nets57. This necessitates the assumption of an interphase role at the onset of percolation and conductivity. However, to the best of our knowledge the limited number of models in this area cannot simulate the tunnels and interphase with respect to the conductivity of nanocomposites.The large surface area of nanofillers frequently results in the development of interphase districts among the polymer media and nanofillers in nanocomposites59. Graphene-based nanocomposites are ideal for fabricating the low-cost and efficient electrodes, because of their unique properties causing high sensitivity, good selectivity and low-limit detection62. However, there is not a simple model predicting the electrical conductivity of graphene-filled nanocomposites in biosensors.Biosensors with high sensitivity and good selectivity are important in the medical fields such as cancer. Recently, various nanomaterials were used to design the effective biosensors for the detection of breast cancer cellsIn this study, the contact region between adjacent nanoparticles is considered by increasing the diameter of graphene nanosheets. The resistances of the contact region and graphene are assumed in a simple model to estimate conductivity. Moreover, the filler dimensions express the percolation threshold and effective filler concentration. Therefore, the developed model can predict conductivity using numerous graphene, interphase, and tunnel factors. Empirical records and parametric analyses are used to examine the suggested model. The developed model can provide precise prediction of conductivity, suggesting valuable strategies for the optimization of multifunctional products.The contact regions between the nanoparticles can be considered by extending the nanosheets. The total resistance of the extended nanosheets is calculated and its effects on the conductivity of nanocomposites are examined.The two possible configurations of contacts between randomly dispersed nanosheets are expressed as crossing and overlapping, as shown in Fig. f and Rc represent graphene and contact resistance, respectively,The total resistance of an extended nanosheet is suggested to be:f is expressed as63:f, and t are the diameter, cross-sectional area, conductivity and thickness of the graphene nanosheet, respectively.Rg) and the polymer tunneling resistance (Rt) as:In addition, the contact resistance includes the intrinsic resistance of the nanosheets on both sides of the tunneling spaces and the tunneling resistance introduced by the insulating matrix layer into the tunneling regions. Therefore, the contact resistance is expressed by the resistances of the graphene fraction between two contacts  can be disregarded when it is too low. In addition, Eq. An equation for nanocomposite conductivity due to accidental dispersal of CNTsWhen the total conductivity of the extended nanosheets from Eq. As mentioned, the interphase regions around graphene can promote the effects of nanoparticles on conductivity by network contribution.64 is calculated as:i is the interphase depth.The interphase volume fraction in nanocomposites63 because both graphene and the surrounding interphase control the conductivity of nanocomposites.The optimal graphene volume portion in the samples contains filler and interphase concentrations65 as:Additionally, the onset of percolation in randomly distributed graphite nanosheets in polymer nanocomposites has been proposedThis equation does not reflect the interphase and tunneling roles in the percolation phenomenon, while they form around the nanosheets and shift the onset of percolation.The subsequent equation can be developed based on interphase and contact districts as:66, was expressed as:Furthermore, only a portion of the nanoparticles was employed in the nets at the onset of percolation, whereas others were detached in the sample. f, the portion of net in the sampleion Eqs.  and 15 aFinally, the model developed using Eq. 67, polyimide (PI)   (PET)  for the PVA, PI, ABS, and PET samples are , , , and  nm, respectively. PI/graphene nanocomposite yields the highest values of , whereas ABS/graphene yields the smallest values. Therefore, it is possible to estimate and evaluate the extents of the interphase and tunneling based on the onset of percolation. Generally, a low percolation threshold is attained in samples comprising narrow and large nanosheets, profuse interphase, and large tunnels  (PVA)  can be used to calculate the effective filler concentration (Eq. f = 105 S/m. Figure The values of (ttion Eq.  and f astion Eq. . Consequi = 4 nm, σf = 105 S/m, d = 5 nm, and ρ = 200 Ω m.The significance of all the factors on conductivity is described to validate the developed model. The average values of the variables in all plots are t = 2 nm, Figure 71, and a few studies have shown a direct relationship between these factors65. However, the large tunneling spaces limit the transfer of charges because of the intrinsic insulating nature of the polymer matrix in these regions. Therefore, the developed equation rationally expresses the impacts of “t” and “d” on the conductivity.Thin nanosheets favorably govern the conductivity of the nanocomposite because they yield high operational filler attentiveness Eq.  and low f are also shown in Fig. f. The variations in conductivity by 34. Conversely, the significant conductivity of graphene nanosheets compared to polymer matrices mainly decreases the resistance of the graphene nanosheets in the networks and contacts. Accordingly, the high conductivity of graphene considerably minimizes the Rf (Eq. g (Eq. f cannot manipulate the conductivity of nanocomposite. However, certain studies have reported that the filler conductivity controls the conductivity of the sample because they commonly do not pay attention to the contact resistance68. Consequently, the developed model correctly expresses the roles of An extraordinary concentration of nanoparticles logically increases conductivity because it increases the segment of the conductive phase in the sample, which produces conductive paths for electron transfer. In reality, the concentration of conductive graphene in the nanocomposite is significant because only graphene controls the conductivity of the nanocomposite in the presence of an insulated medium. However, a significantly higher concentration of nanoparticles after percolation beginning negligibly affects conductivity because they fail to considerably change the performance of networkse Rf Eq.  and Rg (i and D. The small ranks of these factors decrease conductivity, but extraordinary conductivity is observed at high ranges of these terms. ti < 3 nm and D < 1.75 μm produce an insulated nanocomposite, but ti = 10 nm and D = 4 μm cause the conductivity of 0.06 S/m. Accordingly, both ti and D as interphase thickness and graphene diameter directly alter conductivity. This evidence is reasonable because these parameters positively affect the properties of conductive networks.Figure 72, but this interesting item has not been studied for polymer graphene samples.A thick interphase enhances the effective filler concentration Eq. , and dec73, but its direct role in the conductivity of nanocomposites has been limitedly discussed in previously studies.The direct character of D in the conductivity is justifiable because large nanosheets lower the percolation threshold, which changes the size and density of filler networks. Large nanosheets can produce bulky nets in the sample, which facilitates electron transportation. In addition, the large nanosheets diminish the tunneling resistance introduced by the polymer matrix Eq.  because Figure f decreases the resistances of other parts in R, as mentioned. Therefore, ρ significantly changes the conductivity and resistance of extended graphene, which play a key role in the conductivity of the entire nanocomposite. Clearly, a high ρ indicates high resistance against the transfer of electrons in the tunneling spaces, which decreases the conductivity of nanocomposite. Moreover, f reasonably governs conductivity because it represents the scope and density of the conductive nets in the sample. Meanwhile, the extent and efficiency of conductive networks determine the level of charge transportation and electrical conductivity in nanocomposites75; therefore, more optimized conductivity owing to relatively high f is logical. So, the present model accurately demonstrates the associations of conductivity to ρ and f.A high ρ enhances the general resistance of the extended graphene in the nanocomposite based on Eq. Finally, the conductivity is plotted at different values of The contact region between the nanosheets was assumed by extending the graphene nanosheets, and its effect on conductivity was evaluated. In addition, a simple model was developed to express the conductivity based on the graphene size, interphase depth, and tunneling distance. The experimental results from previous studies and parametric examinations were used to analyze the proposed model, confirming the approximations of the advanced model for the conductivity of the nanocomposites. The insulated polymer layer at the contact region mainly controls the resistance of the extended nanosheets and the conductivity of the nanocomposite because graphene intrinsically has a negligible resistance. Additionally, thinner and larger nanosheets and thicker interphases increase the conductivity of nanocomposites because they can enhance the effective filler fraction and decrease the percolation threshold to produce large nets. A high tunneling distance decreases the percolation beginning, but increases the tunneling resistance and diminishes electron transfer. Moreover, a relatively high effective filler portion and relatively low percolation threshold yield increased conductivity in nanocomposites. The advanced model is applicable to improve the performance of biosensors containing polymer graphene nanocomposites for detecting the breast cancer cells.