Idiopathic pulmonary fibrosis (IPF) is the most rapidly progressive and fatal of all fibrotic conditions with no curative therapies. Common pathomechanisms between IPF and cancer are increasingly recognised, including dysfunctional pan-PI3 kinase (PI3K) signalling as a driver of aberrant proliferative responses. GSK2126458 is a novel, potent, PI3K/mammalian target of rapamycin (mTOR) inhibitor which has recently completed phase I trials in the oncology setting. Our aim was to establish a scientific and dosing framework for PI3K inhibition with this agent in IPF at a clinically developable dose.We explored evidence for pathway signalling in IPF lung tissue and examined the potency of GSK2126458 in fibroblast functional assays and precision-cut IPF lung tissue. We further explored the potential of IPF patient-derived bronchoalveolar lavage (BAL) cells to serve as pharmacodynamic biosensors to monitor GSK2126458 target engagement within the lung.We provide evidence for PI3K pathway activation in fibrotic foci, the cardinal lesions in IPF. GSK2126458 inhibited PI3K signalling and functional responses in IPF-derived lung fibroblasts, inhibiting Akt phosphorylation in IPF lung tissue and BAL derived cells with comparable potency. Integration of these data with GSK2126458 pharmacokinetic data from clinical trials in cancer enabled modelling of an optimal dosing regimen for patients with IPF.Our data define PI3K as a promising therapeutic target in IPF and provide a scientific and dosing framework for progressing GSK2126458 to clinical testing in this disease setting. A proof-of-mechanism trial of this agent is currently underway.NCT01725139, pre-clinical. Is there a scientific rationale for the use of a clinically advanced pan-PI3 kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitor in idiopathic pulmonary fibrosis (IPF)?We provide a comprehensive scientific and dosing framework for targeting PI3 kinase signalling in IPF with the pan-PI3 kinase/mTOR inhibitor, GSK2126458, based on the exploration of novel functional endpoints in patient-derived cells and precision cut lung slices.This study provides key data to support the progression of this agent to a proof-of-mechanism trial in patients with IPF and further proposes a roadmap for the repositioning of existing oncology agents as novel therapeutic agents in the IPF setting with minimal requirement for the additional use of experimental animals.Idiopathic pulmonary fibrosis (IPF) represents one of the most rapidly progressive fibrotic conditions with a median survival of 3.5 years from diagnosis,Fibrotic foci, the sentinel lesions in IPF, comprise fibroblasts and α smooth muscle actin positive (αSMA+) myofibroblasts embedded in a type I collagen-rich matrix. These lesions are thought to represent the leading edge of the relentless fibrotic response and arise as a result of a highly abnormal wound healing response characterised by dysregulated epithelial/mesenchymal crosstalk and a complex network of proliferation and differentiation signals received from a remodelled and homeostatically degenerate microenvironment1.in vitro and in tumour necrosis factor α induced fibrosis in vivo.20Class 1 PI3K form an important oncogenic signalling node, integrating signals from a variety of inputs including tyrosine kinase receptors, G-protein coupled receptors and activated Ras,https://clinicaltrials.gov/ct2/show/NCT00972686).GSK2126458 is a potent, highly selective pyridilsulfonamide inhibitor of class 1 isozymes of PI3K in addition to mammalian target of rapamycin (mTOR).in vitro pharmacological assessment of GSK2126458 and related development compounds in lung IPF and non-IPF control fibroblasts. We also assess inhibitor effects using novel functional endpoints in precision-cut IPF tissue slices, and further evaluate pAkt levels in IPF bronchoalveolar (BAL) cells as a potential pharmacodynamic (PD) biomarker to monitor target engagement in future clinical studies. Integration of these data with pharmacokinetic (PK) data for GSK2126458 from oncology trials enabled modelling of an optimal dosing regimen for IPF and the progression of GSK2126458 to an IPF proof-of-mechanism (PoM) study . As well as providing a rationale for progressing a novel therapeutic agent in IPF, these studies further provide a new paradigm for the future re-positioning of existing drugs as novel anti-fibrotic agents.The aim of the present study was to evaluate the scientific and dose rationale for re-positioning GSK2126458 as a potential novel therapeutic agent for IPF. We explore evidence for PI3K pro-fibrotic signalling in IPF lung tissue in combination with performing All human samples were obtained with informed signed consent and with research ethics committee approval . Patients with IPF were diagnosed in accordance with current international guidelines.Primary human lung fibroblasts (LFs) were grown from explant cultures of IPF (IPF-LF) or non-IPF control (C-LF) lung tissue, and cultured as previously described.10.1136/thoraxjnl-2015-207429.supp1Supplementary dataS473, pAktT308, αSMA and CD68 was conducted on 4 μm formalin-fixed paraffin-embedded serial sections of human lung biopsy material from n=12 patients with IPF, using the avidin–biotinylated HRP enzyme complex method (Vector Laboratories). Confocal dual-immunofluorescence microscopy for these markers was also performed on representative fibrotic foci. See Immunostaining for pAkt2/100% humidity) prior to incubation with the PI3K inhibitors Compound 1 or GSK2126458. The effect of short-term exposure (2 h) to Compound 1 on Akt phosphorylation was assessed by Milliplex Map (Millipore) bead assay of lung slice homogenates prepared in ice cold PhosphoSafe buffer (Millipore). In separate experiments, the effect of GSK2126458 on levels of the collagen formation marker P1NP in tissue supernatant was assessed by proprietary competitive ELISA (Nordic Bioscience) as previously described.Precision cut slices of IPF lung, 8 mm, were cultured for 24 h in DMEM supplemented with 0.4% FCS (5% COThe effect of GSK2126458 on FCS-induced Akt phosphorylation in C-LFs (n=2) and IPF-LFs (n=5) was assessed by Meso Scale Discovery (MSD) system. Phosphorylation events (pAkt and pSMAD2) in C-LFs were also assessed by Western blot. Densitometric analysis of Western blots was performed using ImageQuant TL v8.1 software . The intensity of bands in phospho-protein blots was divided by the intensity of the total protein following stripping and re-probing. Values were expressed as a ratio of the positive (stimulated) control. The effect of GSK2126458 on bronchoalveolar lavage fluid (BALF) cell pellet obtained from patients with IPF (n=6) undergoing routine diagnostic BAL was also assessed by MSD. See The effect of GSK2126458 on FCS-induced proliferation in control (n=2) and IPF-derived primary human LFs (n=5) was assessed by MTS assay. Fibroblast proliferation was also assessed by 5-ethynyl-2′deoxyuridine (EdU) incorporation into DNA of primary human LFs . Fibroblast and HBEC apoptosis was assessed by caspase 3,7 activation. See Col1A1 gene expression in confluent fibroblast monolayers following TGFβ stimulation was assessed by RT-PCR following TRIzol extraction as per the manufacturer's instructions (Thermo Fisher). RNA was DNAse treated using a DNAfree kit (Ambion) and real-time RT-PCR conducted using the MESA GREEN qPCR MasterMix Plus for SYBR Assay (Eurogentec). Detailed methods are provided in the S473 and AktT308 localised to classic spindle-shaped, αSMA+ myofibroblasts and epithelium overlying fibrotic foci and cells morphologically characteristic of capillary endothelium  to explore evidence of functional PI3K signalling in areas of active fibrosis in IPF lung biopsy material (representative sections from n=12 patients shown), assessing the phosphorylation state of the critical downstream kinase, Akt. lium see  S1A,C,E.T308 see  S1A,C,G.T308 see  S1B,D,F.T308 see . These spAktS473 A–F. In t located M–R. αSMApAktT308 G–L.Studies performed in live cultured precision-cut lung slices obtained from a patient with IPF confirmed prominent Akt phosphorylation in lung tissue and this signal was reduced in a concentration-dependent manner following incubation with a closely related analogue of GSK2126458, Compound 1  (see onl50=0.84 nM (range 0.43–1.64), n=2 donors) and IPF-LF (50=1.52 nM (95% CI 0.73 to 3.18), n=5 donors) in IPF-LF. S473 phosphorylation. 50=18.70 nM , IPF-LF geometric mean=23.64 nM (95% CI 13.61 to 41.07), n=5 donors) assessed by MTS assay. The inhibitory effects of GSK2126458 on FCS-induced fibroblast proliferation were confirmed using a second assay based on the incorporation of the modified thymidine analogue, EdU, into newly synthesised DNA (Click-iT EdU). The IC50 for GSK2126458 obtained in this assay system was comparable to that obtained in the MTS assay ). Investigation of the effect of GSK2126458 on fibroblast apoptosis , showed that apoptosis was not detectable until concentrations ≥3 μM (We next assessed the effect of GSK2126458 on Akt phosphorylation and proliferation of primary IPF and non-IPF control LFs (IPF-LF and C-LF). GSK2126458 inhibited serum-induced pAkt in C-LF  revealed that macrophages within IPF alveolar spaces were highly immunoreactive for pAkt. We therefore reasoned that since macrophages are a prominent cell type in IPF BALF, this observation could be exploited to develop a PD biosensor to monitor in vivo inhibition of PI3K signalling by GSK2126458.IHC studies (50=0.58 nM (95% CI 0.40 to 0.86)). The inhibitory profile of GSK2126458 was further found to be maintained in BALF cells re-suspended in ice-cold saline for up to 35 min following incubation with the drug (data not shown).BALF differential cell counts confirmed that macrophages formed a prominent cell type n=6, see  S5. Akt in vitro studies were integrated with human PK data for GSK2126458 from ongoing clinical trials in patients with advanced solid tumours , according to the scheme outlined in To develop a dose rationale for GSK2126458 for future IPF clinical trials, the data from these The observation that the epithelium also displays a prominent pAkt signal lead us to further investigate the potential effect of GSK2126458 on epithelial cell apoptosis. 1 implicated as a critical mediator of this process.1 signalling.1-induced fibroblast collagen production.Progressive, excessive and disorganised deposition of collagen and other extracellular matrix (ECM) proteins underlies the gross remodelling leading to loss of lung function in IPF, with TGFβ1 (1 ng/ml) stimulation. 1 induces rapid phosphorylation of SMAD2 peaking at 2 h, with pAktS473 exhibiting a slower kinetic peaking at 12–24 h (COL1A1) gene expression , and leads to a reduction in cell number with an IC50 of 1.66 μM (95% CI 0.51 to 5.43). Induction of caspase 3,7 in molecular crowded conditions is consistent with concentrations of GSK2126458 which cause reduction in cell count, suggesting apoptosis in crowded conditions may be responsible for the observed reduction in cell number  in IPF tissue slices using a competitive ELISA based on a proprietary monoclonal antibody.PI3K represents a key oncogenic signalling node, implicated in a range of cellular processes from inflammation to cancer. More recent evidence also suggests a role for this pathway in fibrosis, however to the best of our knowledge there are currently no PI3K agents in clinical development for IPF or any other fibrotic condition. The aim of the current study was to further explore the rationale for targeting PI3K signalling in IPF and to define the pharmacological profile of a potent and clinically advanced PI3K/mTOR inhibitor, GSK2126458, as a novel anti-fibrotic.T308) and serine 473 (pAktS473) to initiate downstream signalling. The initial focus for our PI3K pathway validation studies in IPF was therefore to perform detailed IHC studies to determine Akt phosphorylation in IPF biopsy tissue. These studies showed demonstrable immunoreactivity for pAktS473 associated with activated myofibroblasts within IPF fibrotic foci, as previously suggested.T308 immunostaining associated with these myofibroblasts and thus provide the first evidence of full Akt activation in situ in this disease context. Immunofluorescent confocal co-localisation studies further provide the first evidence of cell-specific differential phosphorylation of Akt: whereas pAktT308 immunostaining predominates in myofibroblasts and a thin band of cells located at the epithelial–mesenchymal border of fibrotic foci, pAktS473 immunostaining was evident in both the epithelium and myofibroblasts. Moreover, heterogeneous distribution and phosphorylation of Akt were observed in bronchial epithelium and macrophages in the IPF lung. Differential phosphorylation of Akt has not been extensively studied; however in cancer, it has been proposed to influence the interactions of Akt with its substrates and thereby influence cell motility and invasion.T308 relative to pAktS473 is associated with poor prognosis.PI3K mediates the conversion of phosphatidylinositol 4,5 bisphosphate (PIP2) to phosphatidylinositol 3,4,5 trisphosphate (PIP3) at the plasma membrane, inducing the recruitment and phosphorylation of Akt at threonine 308 , GSK2126458 would significantly impact fibroblast PI3K signalling and proliferation in the lungs of patients with IPF.1-induced myofibroblast collagen production, based on limited literature reports suggesting the involvement of PI3K in SMAD-independent TGFβ1 signalling.1-induced myofibroblast collagen deposition at concentrations around the 100 nM range.The decision to progress GSK2126458 to a PoM trial in IPF was predicated on an appropriate dose rationale for this compound as a fibroblast anti-proliferative agent, based on the widespread evidence linking this pathway to cell growth and proliferative responses in multiple cell types and disease settings.1 signalling at clinically attainable doses, while potentially sparing its essential homeostatic and tumour suppressor functions. This is a particularly important consideration in patients with IPF who are at a heightened risk of developing lung cancer.39Our final aim was to directly link PI3K/mTOR signalling to pro-fibrotic collagen formation in IPF lung tissue using an ex vivo human tissue model. Type I collagen is the most represented extracellular protein in the lungs and its dysregulated turnover is a hallmark of fibrosis. During maturation of type I collagen, soluble pro-collagen is processed to its insoluble form by carboxy and amino terminal endopeptidase cleavage, generating peptide fragments such as the N-terminal P1NP which can be monitored as a sensitive biomarker of collagen formation.1-induced collagen production in IPF fibroblasts. Population modelling and integration of preclinical biomarker data with human PK data has enabled us to develop a dosing framework which should safely and effectively engage PI3K signalling in the lungs of patients with IPF, providing support for progressing GSK2126458 to further clinical evaluation in IPF in a dose-finding, double-blind, placebo-controlled study . To the best of our knowledge, this represents the first IPF clinical study aimed at assessing target engagement and tolerability of a PI3K/mTOR inhibitor in this disease setting.In conclusion, we have considerably extended the scientific rationale for targeting PI3K signalling in IPF using patient-derived cells and lung tissue. We provide evidence for active PI3K signalling in the fibrotic foci of IPF patients together with data that GSK2126458 attenuates serum-induced proliferation and TGFβ


The neurotransmitter dopamine (DA) inhibits the fibrillisation of α-syn into amyloid, and promotes α-syn aggregation into SDS-stable soluble oligomers. While this inhibition of amyloid formation requires the oxidation of both DA and the methionines in α-syn, the molecular basis for these processes is still unclear. This study sought to define the protein sequences required for the generation of oligomers. We tested N- (α-syn residues 43–140) and C-terminally (1–95) truncated α-syn, and found that similar to full-length protein both truncated species formed soluble DA:α-syn oligomers, albeit 1–95 had a different profile. Using nuclear magnetic resonance (NMR), and the N-terminally truncated α-syn 43–140 protein, we analysed the structural characteristics of the DA:α-syn 43–140 dimer and α-syn 43–140 monomer and found the dimerisation interface encompassed residues 43 to 60. Narrowing the interface to this small region will help define the mechanism by which DA mediates the formation of SDS-stable soluble DA:α-syn oligomers. Parkinson's disease (PD) is a progressive neurodegenerative disorder characterised by severe motor dysfunction, muscular rigidity and resting tremor.  PathologThe loss of dopaminergic neurons in the substantia nigra, and the subsequent depletion of dopamine (DA) in the striatum is a key feature of PD. α-syn expression can regulate DA metabolism since α-syn knockout mice have reduced striatal DA levels and an attenuated DA-dependent locomotor response to amphetamine.  There isThere is a clear difference in behaviour between α-syn and the DA:α-syn oligomer since the DA:α-syn oligomer cannot interact with lipid vesicles or cause membrane permeability while α-syn (in the absence of DA) does.  While DAStructural analysis using atomic force microscopy indicated the DA:α-syn oligomers possessed non-fibrillar morphologies. , 24 ElecFull-length (1–140) human α-syn cDNA sequence was cloned into the vector pRSETB  and expressed and purified as previously described.  PurifiedThe α-syn 1–60, 1–95, 43–140, H50N, T75P constructs were made using the QuikChange Site Directed Mutagenesis system . α-syn 1–60 was also produced synthetically using FMOC peptide synthesis . The α-syn 43–140 construct has a Met as the first residue. All truncated and mutant α-syn proteins except α-syn 1–60 and 1–95 were expressed and purified as for wildtype α-syn above. The α-syn 1–60 and 1–95 proteins were purified by ammonium sulfate (50%) precipitation, whereby solid ammonium sulphate was added to the lysed cell mixture (v/v) and stirred overnight at 4°C. Following centrifugation at 3200 × g for 1 hour at 4°C, the supernatant discarded and the pellet resuspended in 10 mM sodium phosphate buffer pH 7.5. After boiling for 20 mins and centrifugation at 3200 × g for 1 hour at 4°C the supernatant was collected. The supernatant was desalted using a PD-10 desalting column  and then loaded on a HiTrap SP Sepharose FF cation exchange column. Bound α-syn 1–60 and 1–95 were eluted using a linear salt gradient from 0 to 1M NaCl in 20 mM Tris HCl at pH 8.5. Fractions containing α-syn 1–60 and 1–95 were pooled and lyophilised. The sample was resuspended in 100 mM ammonium bicarbonate pH 7.5 and loaded onto a Sephacryl 300 SEC column  and eluted isocratically with 100 mM ammonium bicarbonate (pH 7.5) at a flow rate of 1mL/min. α-syn 1–60 containing fractions were pooled, dialysed and lyophilised. Protein identities were confirmed by mass spectrometry. The α-syn 43–60 peptide was synthesised using FMOC peptide synthesis 15N) or doubly  for NMR studies. [600 of ~0.6 was achieved, the cells were pelleted by centrifugation at 3200 × g for 15 minutes at 4°C. Cells were washed twice, centrifuging after each wash with M9 minimal media to remove contaminating LB media. Cells were resuspended in M9 minimal media containing either 15NH4Cl or 15NH4Cl and 13C glucose and allowed to equilibrate at 37°C shaking at 220 rpm for 2 hours. Expression was induced with 1 mM IPTG overnight at 37°C. Cells were harvested by centrifugation at 3200 × g, 1 hour at 4°C. Cell pellets were stored at -20°C until lysis and purification were performed according to the method outlined above. Different batches of the protein being expressed and purified during this study.α-syn was isotopically labelled either singly . The concentration of stock solutions were determined by UV absorbance measurements using an extinction coefficient of 5120MSamples were prepared in SDS sample buffer  (v/v) and heated at 100°C for 10 minutes. The samples, unless otherwise stated, were separated on a 12% Bis-tris SDS-PAGE gel (Life Technologies) and the proteins visualised by silver staining according to manufacturer’s instructions (Bio Rad). Some samples were analysed on a Novex 16% Tricine SDS-PAGE gel (Life Technologies) according to the manufacturer’s instructions.Oxidised DA was generated by incubating 2mM DA in PBS pH 7.4 at 30°C and shaking for 28 days. The reaction was then centrifuged at 200,000 × rpm for 60 min to obtain a pellet (insoluble oxidised DA corresponding to polymerised oxidised DA) and a supernatant (soluble oxidised DA) fraction. The pellet fraction was washed 3× with water and resuspended in the original volume with water. The supernatant fractions were analysed by ESI-MS and an UV-visible absorbance spectrum acquired between 200–700nm confirmed the absence of un-oxidised DA in the sample.DA mediated α-syn oligomerisation was performed as previously described  using 20Oligomerisation of α-syn for NMR analysis was performed by incubating 15mg of α-syn 43–140 at a concentration of 200 μM with 2 mM DA at 37°C on a heat block for 7 days to ensure maximal oligomerisation had occurred. After 7 days, the mixture was centrifuged 100,000 × rpm for 1 hour at 4°C and the supernatant collected. The supernatant of the crude reaction mixture was loaded onto a Superdex 200 16/60 GL SEC column . Fractions were eluted in 10 mM sodium phosphate pH7.5. Monomer and dimer-containing fractions were pooled and concentrated using an Amicon centrifugal unit with a molecular cut-off (MWCO) of 10 kDa. The monomer was concentrated using a unit with a 3 kDa MWCO. Different batches of the oligomers were generated and purified during this study.Circular dichroism (CD) measurements were performed on a JASCO 815 CD spectrometer , using the Jasco software. Far UV-CD spectra were collected between 180–250 nm at 37°C. Measurements were recorded at 50 nm/min with a 1 nm bandwidth and a 2s response time, averaging 3 accumulation scans per measurement. All spectra were background subtracted, and smoothed with the default algorithm in the Jasco software. Experiments were performed in triplicate.2O/90% H2O or 100% D2O as appropriate. 1H,13C-HSQC spectra were acquired on α-syn, at natural abundance. All double-resonance spectra were acquired with 2048 complex data points in the directly detected dimension and 512 complex data points in the indirect dimension.NMR spectra were acquired on a Bruker-Biospin Avance 800MHz spectrometer equipped with a cryogenically cooled probe. All experiments were performed at 5°C, and samples were typically 0.5mM protein in 0.5mL 10mM phosphate buffer pH 5.5 with either 10% D1H, 15N NOESY-HSQC with a mixing time of 100 ms, 1H, 1H NOESY with a mixing time of 300 ms, 1H TOCSY with a mixing time of 50 ms, 1H, 15N-HSQC, 1H, 13C-HSQC, HNCO, HN(CA)CO, HN(CO)CA, HNCA, HNCACB, CC(CO)NH, HNHA, and HNHB. [A series of standard two-dimensional (2D) and three-dimensional (3D) spectra were recorded to obtain sequence specific assignments, these included nd HNHB. Spectra wnd HNHB. 1H,15N X-filtered NOESY-HSQC experiment were performed using sample prepared by incubating α-syn in a reaction containing 50% unlabelled α-syn and 50% 13C, 15N labelled α-syn with DA in a 1:10 protein to DA ratio. This reaction was mixed and incubated at 37°C for 7 days. The solution was then centrifuged 100,000 × rpm, 1 hour at 4°C and the supernatant was then separated by SEC on a Superdex 200 16/60 column  to isolate the dimer. The dimer fractions were eluted in 10 mM sodium phosphate buffer at pH 7.5 and concentrated using an Amicon centrifugal filter unit  with a MWCO of 10 kDa to a final volume of ~500μl.A 120 ms Sequencing grade trypsin  was added to a solution containing either α-syn 43–140 monomer or α-syn 43–140 dimer in 50 mM Tris-HCl pH 7.5 at a 1:50 trypsin to protein ratio. Typically, 1mg of protein and 20 μg of trypsin was used in each experiment. The reaction was incubated at 37°C for 18 hours and analysed using reverse phase HPLC and ESI-TOF-MS.ESI-IMS-MS was performed as described.  All reagAggregation and spectroscopy experiments were repeated at least three separate times and were performed with different batches of expressed and purified protein and different batches of purified oligomers.To define which regions of α-syn are required for the formation of the DA-mediated soluble oligomers, we tested N- and C-terminal truncated proteins . α-syn 4The generation of DA mediated α-syn oligomerisation requires oxidation of DA to occur  and it iTo study the biophysical properties of the DA:α-syn 43–140 species we reacted α-syn 43–140 with DA and the dimer and monomer were purified using SEC and their identity confirmed by SDS-PAGE  and ESI-The DA:α-syn 43–140 dimer was characterised by far-UV CD spectroscopy and gave a single minima at λ = 200 nm that is indicative of a predominately random coil structure. A similar spectrum was observed for the DA:α-syn 43–140 monomer . TherefoTo investigate the stability of the DA:α-syn 43–140 dimer, we exposed it to trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP), which are known to dissociate oligomers to their monomeric species. , 36 The To further analyse the conformational properties of the DA:α-syn 43–140 protein we employed electrospray ionisation—ion mobility—mass spectrometry (ESI-IMS-MS). This method allows the gross conformation state and non-covalent interactions of a protein to be determined. , 38 The To analyse the behaviour and structure of the DA:α-syn 43–140 oligomers in solution we studied DA:α-syn 43–140 using NMR. This protein construct was chosen to reduce the spectral complexity arising from the presence of multiple repeat sequence motifs in α-syn and the resultant chemical shift redundancy.15N) or doubly  labelled protein (refer Methods). A proton nitrogen correlation spectrum  of the DA:α-syn 43–140 monomer was recorded at pH 5.5 to ensure favourable amide proton exchange rates. The 1H, 15N-HSQC spectrum of the DA:α-syn 43–140 monomer displayed the characteristic narrow chemical shift dispersion in the amide 1H resonances for an IDP [1H, 15N HSQC spectrum of DA:α-syn 43–140 dimer also showed the characteristic lack of chemical shift dispersion for the amide 1H resonances expected for an IDP  abuts 43–60 and is required for α-syn fibrillisation. A proline scan of this region identified residues that inhibited fibril formation, such as threonine 75.  To examiThe N-terminally truncated 43–140 α-syn dimer was chosen for structural characterisation, over the C-terminal truncation or full-length α-syn, as α-syn 43–140 formed DA-mediated soluble oligomers with a similar oligomeric pattern to full length α-syn but significantly simplified the NMR analysis by reducing the number of sequence repeats to minimize chemical shift redundancy in the spectra. Moreover, the ESI-IMS-MS analysis of 43–140 α-syn showed it behaved in a similar manner to full-length α-syn by occupying both extended and compact conformations under neutral conditions. In the presence of DA the highly extended state monomeric state bound three DA ligands without the need to oxidise the Met residues. These similarities between 43–140 and full-length α-syn support the utility of using the 43–140 construct to investigate which regions of α-syn are required for the formation of the DA-mediated oligomers. In this study we compared the monomeric and dimeric species in order to understand the mechanism by which DA mediates α-syn oligomerisation.1H, 15N HSQC spectrum showed amide resonances with limited chemical shift dispersion, characteristic of an IDP [1H,15N HSQC of α-syn 43–140 dimer were unshifted compared with those in the monomer, indicating that there is not a gross conformational change when compared to the monomer. Amide resonances of T43, V48, V49, H50, G51, T59, K60, E114, M116, V118, E126, M127, and S129 for the α-syn 43–140 dimer, are shifted or broadened compared to those in the monomer. These changes are centred around the N-terminus and the M127 residue at the C-terminus and indicates changes in chemical environment surrounding specific residues upon interaction with DA. Furthermore, the similarity in the 1H,15N-HSQC spectra between the dimer and monomer α-syn 43–140 suggests that, only a limited number of residues are modified by DA.CD and NMR spectra showed the DA:α-syn 43–140 dimer adopted a largely unstructured conformation in solution. The f an IDP , while Cf an IDP  The majoWhile CD, NMR and mass spectrometry data identified very few differences between the DA:α-syn 43–140 dimer and monomer, the dimer displayed altered behaviour in a membrane-mimetic environment. The presence of SDS caused α-syn 43–140 monomer to adopt α-helical structures and similar behaviour has been observed for full length α-syn. , 54–56 IOur studies expand upon the NMR and biophysical analysis of full length α-syn modified by DA quinones  which shThis study has provided novel and important data on the structural characteristics of the DA:α-syn oligomer, and the contribution of distinct domains and residues to their formation. We have narrowed the interface to a small region and while the exact residues involved and the nature of the interaction with DA / DA-products remains unresolved, our new data further defines the mechanism by which DA mediates the formation of these SDS-stable soluble DA:α-syn oligomers.S1 FigSilver stained SDS-PAGE gel of the different α-syn proteins treated with either freshly prepared or pre-oxidised DA. No DA refers to the proteins minus the addition DA. Fresh DA refers to DA (200uM) that has been added to the α-syn soon after the DA has been dissolved, as per the other incubations performed in this study, i.e. (TIF)Click here for additional data file.


Sarcoidosis is an inflammatory disease with a wide range of clinical presentations. The manifestations and prognosis in sarcoidosis are dependent upon not only organ involvement but also age and sex. The purpose of this review is to describe the systemic and ocular manifestations of sarcoidosis with a specific focus on sex-dependent difference in presentation and management. Sarcoidosis is more common in women, particularly in patients who present after age of 50 years. Women with sarcoidosis are more likely to develop cystoid macular edema and the mortality rate is higher than that of men. Sarcoidosis is a systemic inflammatory disease of unknown etiology that can target almost any organ of the body. The most commonly involved organs include the lungs, lymph nodes, skin, and eyes . The cliPatients suspected of having sarcoidosis may undergo a battery of diagnostic tests that are not specific for sarcoidosis, but rather markers of granulomatous inflammation. Angiotensin converting enzyme (ACE) may be elevated in 60–70% of patients with sarcoidosis . The serWhile various diagnostic tests can support a diagnosis, none are confirmatory, and, thus, sarcoidosis is considered a diagnosis of exclusion. Experts agree that three criteria must be met prior to assigning a diagnosis of sarcoidosis: (1) clinical or radiologic findings consistent with sarcoidosis, such as pulmonary disease, uveitis, mediastinal hilar lymphadenopathy, or erythema nodosum; (2) tissue biopsy with histologic evidence of noncaseating granulomas; (3) absence of other causes of granulomatous disease . A diagnOcular involvement occurs in 11–83% of cases of sarcoidosis patients and can lead to significant morbidity –18. The Initial management of patients with systemic sarcoidosis is challenging because evidence exists that the use of systemic corticosteroids actually increases the likelihood of relapse . In patiUnderstanding the epidemiology of sarcoidosis is complicated by the variability in presentation and diagnostic criteria and the disease is certainly underdiagnosed. As an example, one recent study reported sarcoidosis in 22% of patients with mediastinal incidentalomas identified on chest CT .Sarcoidosis presents most often in young adults under the age of 50, with the highest incidence reported in patients between 20 and 39 years of age . CountriAs with many inflammatory diseases, sarcoidosis affects women more than men. Three population-based studies performed in three different countries have produced similar findings. In Japan, the rates were 1.2 versus 1.4 per 100,000 in males versus females  and, in The increased incidence of sarcoidosis in females has led some to hypothesize that hormones may be a compounding factor. The Black Women's Health Study (BWHS) followed black women between 1995 and 2009 and determined that factors not associated with an increase in incidence of sarcoidosis included age at menarche, age at menopause, and parity. A reduced incidence of sarcoidosis was noted with a later age at first birth, and a weak association was suggested between recent birth and reduced incidence of sarcoidosis , althougP = 0.003). Uveitis was more common in the elderly group versus the younger group , and 80% of the patients with uveitis in the study were female [A second trend is the recognized second peak of sarcoidosis diagnosed in patients over 50 years of age , 27, 32.e female .The relapse rate of systemic sarcoidosis may also be influenced by sex. White males reportedly have a higher relapse rate of sarcoidosis than white females and African Americans of either gender . In thisThe array of clinical manifestations associated with sarcoidosis is quite varied and includes both constitutional and organ-specific presentations. In any patient with suspected sarcoidosis, a complete review of systems is essential to help characterize the systemic disease and direct diagnostic testing and management. Generalized symptoms of sarcoidosis include fatigue, night sweats, weight loss, arthralgia, and exercise intolerance . Gender Organ-specific involvement is easier to characterize and several sex differences have been identified in this regard. Males tend to have higher rates of pulmonary and cardiac involvement, while females are more prone to peripheral lymph node, skin, eye, and liver disease , 38, 39.Endocrine abnormalities are common and possibly underreported in sarcoidosis. Hypercalciuria and hyperprolactinemia have been reported in up to 30% of patients with sarcoidosis , 42. AbnGenitourinary sarcoidosis will obviously differ between men and women. Among men, clinical signs include testicular swelling and a painless mass in the scrotum , while wSarcoidosis can involve almost any ocular structure, including the globe, orbit, and adnexa. As with systemic sarcoidosis, ocular manifestations of the disease are more common in women –48. In ASeveral studies have demonstrated a second peak of uveitis in patients over the age of 50, and the vast majority of patients in this subset are female , 49, 50.Patients with sarcoidosis have been successfully treated with numerous anti-inflammatory agents, ranging from topical and systemic corticosteroids to antimetabolites and monoclonal antibodies. Because sarcoidosis often occurs in patients of childbearing age, special considerations must be made in patients who may have planned or unplanned pregnancy. The pregnancy class of many medications used to treat sarcoidosis is listed in A recent international poll of sarcoidosis specialists found that 80% of physicians considered MTX their preferred second-line treatment option for sarcoidosis, after systemic corticosteroids . They alTopical and periocular corticosteroids are commonly used to treat uveitis during pregnancy. In the case of topical administration, patients should be educated on punctual occlusion after administering the medication to reduce systemic absorption. Intravitreal bevacizumab, a class C drug, has reportedly been used for choroidal neovascularization, a potential complication of posterior segment inflammation which can lead to significant and permanent vision loss, in pregnant patients. In a small series of 4 patients treated off-label with intraocular bevacizumab, vision improved and no adverse events were observed . The usePatients with sarcoidosis often report a diminished health-related quality of life , with a Extrapulmonary manifestations of sarcoidosis differ by race and sex. Black Americans have a higher prevalence of extrathoracic involvement . A recenDeath from sarcoidosis is closely associated with respiratory, cardiac, neurologic, and hepatic involvement . A recenWomen tend to have higher rates of many autoimmune diseases , includiGender differences may also be related to genetics. A recent Brazilian study found that certain HLA alleles were more likely to be found in mestizos and blacks with sarcoidosis . It is pAlmost every aspect of sarcoidosis, from epidemiology and clinical presentation to treatment options and prognosis, is influenced by patient sex. Men are diagnosed at a younger age than women, and the onset of sarcoidosis in women follows a bimodal distribution with a second peak of onset occurring after age of 50. In this older cohort of patients, chest X-ray may not be sensitive enough to identify pulmonary changes and computed tomography is recommended. Women tend to have more CME and a worse overall visual prognosis than men. Women are more likely to have cutaneous involvement than men, and the mortality rate is higher in women. Several medications used to treat sarcoidosis are contraindicated in pregnancy; therefore, discussions regarding birth control should be thorough and repeated at every visit.


Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp.Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures ( Although some aspects of its superconductivity remain under debate141516171415in situ ARPES measurements on metal decorated graphene20Tc ~ 6 K. Due to the nature of these experiments, however, they could not provide direct evidence of the emergence of intrinsic superconductivity.Graphene, a zero-gap semimetal, can be transformed into a metallic, semiconducting or insulating state by either physical or chemical modification12457891112In this report, we have investigated the possibility of inducing superconductivity in graphene by decorating it with K, Cs, Li and Ca. To this end, we used so-called graphene laminates (GLs) that consist of graphene crystals arranged in a layered manner, similar to bulk graphite. However, unlike in graphite, crystallites within a GL are rotationally disordered and exhibit larger interlayer separations. This is known to result in effective decoupling of individual layers so that their electronic band structure corresponds to that of isolated graphene2324M(T), for Ca-GL and Li-GL. Zero field cooling (ZFC) data for Ca-GL clearly shows a diamagnetic transition at ≈6.0 K . The onset transition temperature found from H = 0 M(T) curves is H the samples clearly exhibit the Meissner effect (inset in M(T) with increasing H: both the diamagnetic response and Tc decrease as expected. The T-dependent upper critical field, Hc2(T)  see  exhibitsR(T) (see Tc ≈ 12 K. The much higher Tc compared to that found in M(T) measurements indicates sample inhomogeneity, possibly due to the presence of some intercalated few-layer graphene  measurements. The relatively small (factor of 2) drop in resistance is due to partial degradation of the sample: unlike all other techniques used in our study, transport measurements required relatively long air exposure of the samples before data could be taken. The resulting partial degradation of the samples was apparent from the colour change (see below) after the measurements; it was also apparent from magnetization measurements that showed an order of magnitude smaller diamagnetic moment compared to Further evidence for superconductivity in Ca-GLs was obtained from the temperature dependence of their electrical resistivity, R(T) see . The zerTo find out whether the observed superconducting response corresponds to a bulk layered system similar to intercalated graphite or, alternatively, is representative of superconductivity within individual graphene crystals, we have prepared mixed laminates where graphene crystallites are interspersed with BN flakes (GBNLs), and RGOLs where graphene flakes have larger separations compared to GLs, ≈3.6 Å versus ≈3.4 Å . The mixTc : d ≈ 5.1 and 5.4 Å vs 4.5 Å  were fabricated as reported earlier232425Metal intercalation was done in either high vacuum or an argon-filled glove box to avoid exposure of the highly reactive alkali-/alkali-earth metals and the intercalated samples to ambient moisture and oxygen. We have used both pure-metal vapour transport10H applied and the magnetisation M measured as a function of increasing temperature, T . The field-cooling (FC) part of an M(T) curve was obtained on cooling the sample to 1.8 K in the same H.Magnetisation measurements were performed on 4 × 4 mm square samples using Quantum Design MPMS XL7 SQUID magnetometer . In the For electrical transport measurements, we have fabricated GL devices in van-der-Pauw geometry, i.e. four contacts were made with silver paint in the corners of a 3 × 3 mm square sample of a graphene laminate. The devices were then intercalated with Ca using vapour transport technique, transferred to a container inside the glove box and quickly cooled down to liquid nitrogen temperature to avoid degradation. Later, the samples were transferred to a liquid helium cryostat, cooled down to 0.3 K and the resistance of the device continuously monitored while cooling. All transport measurements were performed using standard four probe DC measurement techniques using Keithley’s 2400 source-meter and 2182 A nanovoltmeter. Raman spectra were acquired using a Renishaw micro Raman spectrometer with a 514 nm excitation using a laser power <1 mW. Due to the extreme sensitivity of the samples to air, they were sealed inside quartz tubes in the inert atmosphere of a glove box to avoid degradation.Optical reflectivity measurements were carried out using an Energetiq laser-driven light source (available wavelength range 190 nm–2.4 μm), where the light passed through a broadband fibre into a reflective collimator, a neutral density filter wheel and a 70/30 beam splitter before being focused with a 25× objective (NA – 0.65) onto the sample. To prevent degradation of the samples, they were covered with a thin film of paraffin oil and sealed inside a glass cell in the inert atmosphere of a glove box. To eliminate reflection from the glass plate encapsulating the sample, we used a refractive index matching gel. The sample was brought into focus with a three-dimensional stage manipulation system. The reflected light passed back through the lens and beam splitter, before being split again (92/8) to allow a digital image to be simultaneously captured by the camera (8%), with the remaining light (92%) then focused along another broadband fibre to the Ocean Optics spectrometer for analysis. The obtained digital images allowed us to confirm that the samples remained stable (did not degrade) during the measurements by monitoring their colour. The spectra were taken at 345–1040 nm wavelengths, using a silver mirror as a reference.How to cite this article: Chapman, J. et al. Superconductivity in Ca-doped graphene laminates. Sci. Rep.6, 23254; doi: 10.1038/srep23254 (2016).


Graphene by virtue of its structural properties has the potential to address this issue. Studies have indicated that use of monolayer graphene can be used to filter micro volumes of saline solution. Unfortunately it is extremely difficult, resource intensive and almost impractical with current technology to fabricate operational devices using mono-layered graphene. Nevertheless, graphene based devices still hold the key to solve this problem due to its nano-sieving ability. Here we report synthesis of oxidized graphene frameworks and demonstrate a functional device to desalinate and purify seawater from contaminants including Na+ and Cl− ions, dyes and other microbial pollutants. Micro-channels in these frameworks help in immobilizing larger suspended solids including bacteria, while nano-sieving through graphene enables the removal of dissolved ions (e.g. Cl−). Nano-sieving incorporated with larger frameworks has been used in filtering Na+ and Cl− ions in functional devices.The small size of Na Optical, chemical and electrical measurements reveal that these frameworks filter the solution efficiently by utilizing sieving at micro and nano scale. Filtration capability is significantly better than that of mono-layer graphene membranes. Membranes are easy to fabricate, reusable and economically viable. This is expected to have wide implications in meeting the demand for fresh water, a matter of global concern, at lower costExtraordinary properties of graphene make it a potential candidate for nano-sieving in desalination. Molecular dynamics simulations suggests better salt rejection in graphene oxide based frameworks than existing technologies+ and Cl− ions has created a bottleneck in the development of filtration devices to filter these ions from saline solution. De-ionization of saline water is achieved by thermal898111213+ ions. As an alternative to expensive graphene based filters, green methods are being used to synthesize graphene based materials+ and Cl− ions for the production of fresh water from saline source at industrial or individual level; hence there is an urgent need to address this global issue12The small size of NaD/IG ratio of ~0.6471 in their Raman signature shown in top right inset in D/IG ratio can be used to study point like defects in graphene, thereby suggesting the presence of point like defects in the oxidized graphene membrane which act as nanopores for sieving of small ions. This is also supported by UV-Vis signature at ~270 nmThe 3D oxidized graphene framework used in this study was synthesized by charring fresh sugarcane bagasse for about 10 minutes. Thermal processing in air leads to slight oxidation of the 3D graphene frameworks in Analysis of the micrograph suggest that the thermal processing of sugarcane bagasse produces interconnected hierarchical porous structures forming a 3D network of micro-channels made of oxidized graphene. Formation of diffused hexagonal pattern in FFT micrograph is seen in bottom right inset in Microscopic analysis of the membranes after filtration of 0.5 M NaCl solution in + and Cl− ions at room temperature under atmospheric pressure. Results suggest that the filtrate obtained using 3D oxidized graphene membranes qualify to be labeled as fresh water. The filtrate obtained using sea water as feed was also tested for different elemental solvents such as chlorides, residual chlorine, phosphorous and fluorides  at the end of filtering 10 ml and approaches to ~13 g (91.02%) after filtering 490 ml of 0.5 M NaCl solution (−2h−1 was observed for 0.5 M NaCl solution corresponding to an osmotic pressure of ~22.5 bar at room temperature. A device was fabricated (It is observed that ~29.20 mg/ml (99.95%) of NaCl is filtered in the 1solution . The NaC9 mg/ml 9.34% at tbricated  using sybricated .260/I230  as feed solution to the levels much better than the acceptable limits of fresh water (TDS < 990). These are not only simple to synthesize and easy to fabricate and recyclable but also highly economical to use in point of use applications.To conclude, we have synthesized 3D oxidized graphene framework using green method. The membrane fabricated using these frameworks are highly efficient in removing Na2 holes to provide structural stability from flow of tap water. This assembly was finally mounted inside a plastic case. Microstructural characterizations were performed using TEM and FEGSEM. Raman spectroscopy was performed using Witec alpha 300RAS confocal-raman imaging system using 532 nm laser for excitation. The UV-Vis spectrum was obtained using shimadzu UV2600 UV-Vis spectrophotometer. Water quality tests were performed using commercial test kits “Aquacheck”. The details vital parameters test for evaluating the health of water has been provided in Porous 3D oxidized graphene membranes (~1.2 cm diameter) were prepared by thermally processing for device fabrication. The pellet was sandwiched between two plastic filters with ~1 mmHow to cite this article: Pawar, P. B. et al. 3D Oxidized Graphene Frameworks for Efficient Nano Sieving. Sci. Rep.6, 21150; doi: 10.1038/srep21150 (2016).


Sarcoidosis is a multisystem inflammatory disorder of unknown etiology. It shows a great variety of clinical presentation, organ involvement, and disease progression. Lungs and lymphoid system are the most common sites involved with a frequency of 90% and 30%, respectively. Extrapulmonary involvement of sarcoidosis is reported in 30% of patients and abdomen is the most frequent site. Furthermore, peritoneal involvement is extremely rare in sarcoidosis. The case presented here described peritoneal manifestations of sarcoidosis without involvement of lungs. A 78-year-old woman possessing signs of malignancy on blood test and abdominal magnetic resonance imaging underwent laparatomy with a suspicion of ovarian malignancy. The macroscopic interpretation during surgery was peritoneal carcinomatosis. Total abdominal hysterectomy, bilateral salpingo-oophorectomy, peritoneal biopsies, total omentectomy, and appendectomy were performed. Final histopathological result revealed the diagnosis of sarcoidosis. Clinicians must keep in mind that peritoneal sarcoidosis can mimic intra-abdominal malignancies. Sarcoidosis is a multisystem inflammatory disorder of unknown etiology. The cause may be related to a bacterial or fungal infection or an immune response from an unidentified antigen . The genA 78-year-old woman, gravida 4, para 3, presented with complaints of dyspnea, abdominal discomfort, and distension that persisted for one month on December 2014. Her medical history revealed no history of tuberculosis and of asbestos exposure. On abdominal examination, she had abdominal tenderness without rebound or defense signs. Hepatosplenomegaly and lymphadenopathy were not noted on physical examination. Chest examination was dull to percussion over both hemithorax and respiratory sounds diminished at both basal regions. Although blood tests were at normal range, serum CA 125 and CA 15.3 levels were 116 u/mL and 49,1 u/mL, respectively. Ultrasonography of the abdomen confirmed the presence of diffuse ascites. Chest radiography revealed bilateral pleural effusion. Thickening of parietal peritoneum and nodular implantation at right side of lower abdomen and sign of omental cake were detected on T1-weighted fat-saturated, contrast-enhanced transverse images of abdominal magnetic resonance (MR) . T1-weigAn explorative laparotomy procedure was planned with the preliminary diagnosis of intraabdominal malignancy. At laparotomy under spinal anesthesia, miliary white nodules measured 2–5 mm in diameter studded the diaphragm, liver, omentum, gastric serosa, small and large intestines, whole surface of parietal peritoneum, and both ovaries. Furthermore, approximately 1,5 liters of nonbloody ascites was aspirated from intraabdominal cavity. The sample of ascites was sent for cytological examination. Omental cake appearance was prominent. Interpretation of case was manifestation of peritoneal carcinomatosis. Cytological examination and frozen section pathology resulted in the fact that malignancy could not be excluded. Then we performed total abdominal hysterectomy, bilateral salpingo-oophorectomy, peritoneal biopsies, total omentectomy, and appendectomy. Numerous lymphadenopathies of bilateral iliac, obturator, and paraaortic sites were noted. The size of lymph nodes ranged from 2,0 cm to 5,5 cm in diameter. Enlarged lymph nodes were sampled during the operation. She was discharged from the hospital after uneventful postoperative course at 10th day.Final histopathology demonstrated epithelioid noncaseating granulomas containing multinucleated giant cells in the serosal surfaces of uterus, ovaries, fallopian tubes, peritoneum, and omentum as well as iliac, obturator, and paraovarian lymph nodes . The patThe manifestations of abdominal sarcoidosis are less characteristic. It may mimic neoplastic or infectious diseases such as lymphoma, diffuse metastasis, granulomatous, and mycobacterial infection . The othExudative ascites (bloody and nonbloody) and abdominal pain are the mostly seen clinical presentations. Multiple granulomatous nodules involving peritoneum or a single peritoneal lesion may be seen. Enlarged lymph nodes are detected in nearly 30% of patients, especially in the porta hepatis, para-aortic region, and the celiac axis . InteresOmental cake is an unfavorable sign and mostly caused malignancy. It is associated with infiltration of the omental fat. The other causes of omental cake are inflammatory conditions such as tuberculosis, Crohn's disease, phlegmonous pancreatitis, and granulomatous enterocolitis. The differential diagnosis should also be focused on benign tumors derived from lymphatic, vascular, neuromuscular, or fatty tissues . To our Homogenous hepatosplenomegaly (HSM) is typically related to extrapulmonary sarcoidosis. In 5 to 15% of cases, multiple, hypoechoic, hypodense, and hypointense nodules are scattered in the liver and spleen. HSM in sarcoidosis is easily misdiagnosed as lymphoma, infection, or metastatic disease .Sclerosing peritonitis is a syndrome characterized by abdominal pain, intestinal obstruction, and thickening of peritoneum with massive adhesions. This condition is easily curable by steroid therapy. The other causes of sclerosing peritonitis are bacterial infections (mycobacteria), foreign bodies, peritoneal dialysis, asbestos exposure, carcinoid syndrome, or being idiopathic . Almost Carbohydrate antigen or cancer antigen 125 (CA 125) is a tumor marker secreted by the mesothelial cells lining the peritoneal cavity. It has also been identified on tissues of nonmesothelial origin such as tracheobronchial epithelium, epithelium of pancreas, colon, gallbladder, stomach, kidney and breast, amniotic tissue, placenta, and cervical mucous membrane. Therefore, inflammation of these regions can yield elevated serum levels of CA 125. Elevated CA 125 levels have also been reported in endometriosis, pelvic inflammatory disease, during menstruation and pregnancy, after laparotomy, and in numerous conditions . InteresAlthough isolated occurrence of sarcoidosis in the genital system is rare, uterine and ovarian involvement are most common sites relatively. Like uterine sarcoidosis, most of the ovarian ones are reported in the reproductive age period. A few cases of ovarian sarcoidosis in postmenopausal women were reported as in our case presentation . SymptomIn conclusion, sarcoidosis should be kept in mind for differential diagnosis of intraabdominal malignancies that can affect female genital organs and peritoneum. Therefore, optimum management of such patients should be delivered and inessential invasive procedures can be avoided.


We attribute the high performance to the elimination of possible deep charge traps, most probably at the graphene/GaSe nanosheets interface. This result demonstrates high photoconductive gain and fast photoresponse can be achieved simultaneously and a clean interface is the key to the high performance of these hybrid devices.While high photoconductive gain has been recently achieved in graphene-based hybrid phototransistors using semiconductor two-dimensional transition/post-transition metal dichalcogenides or quantum dots sensitizers, obtaining fast photoresponse simutaneously remains a challenge that must be addressed for practical applications. In this paper we report a graphene/GaSe nanosheets hybrid photodetector, in which GaSe nanosheets provide a favorable geometric link to graphene conductive layer through van Der Waals force. After a vacuum annealing process, a high gain in exceeding 10 The oppositely charged carriers are trapped in the QD layer within their lifetime, providing a photo-gating effect on the PbS-QD/graphene FET (GFET) channel conductance1620q is electron charge, η is quantum efficiency, A is detector area, Φs is incident light photon flux densityl and inversely proportional to the carrier mobility in photoconductive channel μc and the bias voltage Vbias8 reported in graphene/PbS-QD and graphene/TMDC nanosheets hybrid photodetectors161718where oCμm elemental dimension were reported with a peak responsivity of 1.4 A/W under 240 nm illumination31327–108 and the fast photoresponse to visible light with both light-on and light-off time constants as short as 10 ms in the graphene/GaSe-nanosheet FET phototransistors.While these results are exciting, restrictions exist in slow transient response decay time in these hybrid photodetectors with photoresponse time typically in exceeding 100 ms due to the surface/interface charge trap states1624GaSe nanosheets were synthesized from bulk GaSe and details are summarized in Methods2 (90 nm)/Si substrates was patterned into micro-channels and Au/Ti electrodes were fabricated on top. The GaSe-nanosheet/methanol solution was deposited onto the graphene channels to form the graphene/GaSe nanosheet hybrid photodetector. The source-drain current (ID) versus back gate voltage (VBG) curves with/without GaSe nanosheets in dark are compared in ID versus VBG in dark and under 155 mW/cm2 Xenon light illumination taken on a representative graphene/GaSe-nanosheet hybrid GFET is shown in VSD (or Vbias in this paper) was kept at a larger bias of 1 V, which is needed to obtain higher photocurrent as described in the later part of this paper. Under an incident light, the Diract point shifts further to the right side as anticipated from photogenerated hole doping, inducing a positive photocurrent response at zero gate voltage bias as a result of the photo-gating effect, which is qualitatively consistent with previously reported graphene/PbS-QD phototransistorsIBG vs. VBG curves are also shown in The graphene/GaSe-nanosheet interface band diagram is illustrated schematically in 2] and after [2] the vacuum annealing to a 532 nm laser at comparable incident power intensities, and the back gate voltage Vbg = 0 V and source-drain voltage Vd = 1 V were maintained for both measurements. While the two curves follow a similar trend qualitatively, they differ considerably in both the magnitide of the photoresponse, defined as the difference of the source-drain current ID under illunimation with respect to in dark (or photocurrent ΔID), and the photoresponse time constants, defined as the consumed time corresponding to 50% magnitude rise/decay change upon incident light on/off. After the vacuum annealing, the ΔID increased by a factor of eight, which illustrates the importance in achieving a clean GFET channel interface since polar molecules adsorbed the channel respond to the electric field applied to the GFET and reduce the effective gating field sensed by GFETetectors , while t7. For example, at VBG = 0 V and incident power intensity of 198 mW/cm2, the carrier transient time l = 5 μm, μc ~ 320 cm2V−1s−1 [extracted from Vbias = 1 V, and 8 is obtained at lower incident power intensity of 5.7 × 10−3 mW/cm2 in our measurements. This result therefore demonstrates the feasibility of simultaneous achivement of both the high gain and fast response in the graphene/GaSe-nanosheet hybrid GFET photodetectors.It should be noted that this fast photoresponse is obtained together with a high gain in exceeding 10ID as function of source-drain bias voltage VSD  is summarized in VBG of 0 V and laser intensity of 198 mW/cm2. Apparently, the photocurrent ΔID is linearly dependent on the bias VSD in the entire measurement range, as described in equation ID vs. VBG at a constant VSD = 1 V. Interestingly, the maximum photocurrent was observed at ~VBG = 0 V while it decrases monotonically with increasing VBG abosulte value, which is qualitatively consistent with the photoresponse observed under Xenon light, as shown in The photocurrent ΔRI at different laser intensities is summarized in RI with increasing laser power intensity is in good agreement with ideal photoconductive response16RI ~ 3.5 × 105 A/W is obtained at 5.7 × 10−3 mW/cm2, the minimum controllable laser power intensity in our setup, and higher responsivity value is expected at lower incident laser intensity by following the trend in VSD = 1 V, VBG = 0 V and frequencies about 1.6 Hz, giving a detectivity D* up to 1.1 × 1010 cm.Hz1/2/W at 5.7 × 10−3 mW/cm2 intensity for 532 nm incident laser, where detectivity is calculated as Ad is the detection area and RI is lower than the best reported value of 106–107 A/W taken on the graphene/PbS-QD and graphene/TMDC hybrid photodetectors, several factors should be considered before a direct comparison is made. First, it is widely reported that the observed photoresponsivity decreases monotonically with increasing incident light power, and all the previously reported higher photoresponsivity results were obtained at light power intensity much lower than that of this work1618RI decreases linearly in the log-log scale from about 106 A/W at around 10−5 mW/cm2 to about 20 A/W at around 10 mW/cm2RI results were obtained in hybrid photodetectors167 A/W and maximum detectivity of 7 × 1013 cmHz1/2/W were obtained at 8 fW, corresponding to an incident power intensity of 1 × 10−9 mW/cm2 for the laser spot diameter of 1 mm.), considerably higher RI values are expected on graphene/GaSe-nanosheet hybrid GFET photodetectors at lower light intensity. Furthermore, it should be pointed out that the high gain  and fast response time are achieved simultaneously at zero VBG in this work on graphene/GaSe-nanosheets. This is in contrast to the mandatory high VBG in the range of −60 V to −40 V required to observe photoresponse in graphene/MoS2 hybridsRI was observed at VBG ~ −20 V, which is considerably better than the RI at zero VBG by a factor of 3–4. Finally, all the devices studied in this work were made using CVD graphene. In contrast, the high RI records obtained in previous graphene hybrid photodetectors were all obtained on exfoliated graphene flakes16The laser power intensity affects responsivity as summarized in 7 and fast photoresponse with response time constants around 10 ms have been demostrated simultaneously for the first time to our knowledge. In particular, the demonstrated fast and symmetric dynamic photoresponse is so far the best achieved in the graphene-based hybrid devices integrated with quantum dots or other two dimensional materials. The key to this achievement is the elimination of interfacial deep charge traps. The method developed for fabrication of GaSe nanosheets on CVD graphene is robust and low-cost, which is promising for large-scale device fabrication with compatibility to existing microfabrication procedures and on-chip integration with Si-based readout circuits.In summary, we have developed a graphene/GaSe-nanosheet hybrid GFET for photodetection. High gain in exceeding 102 (500 sccm:500 sccm) at 400 oC for 15 min to clean up residues of transfer process37−6 Torr for about three days in the probe station, which was found critical to removing the polar molecules adsorbed to the GFET channel during the device fabrication  was transferred onto heavily doped Si(100) substrate with 90 nm thermal oxide and annealed in Ar:HTransmission electron microscopy (TEM) imaging of the GaSe nanosheets was done at room temperature using a FEI Tecnai F20 XT field emission transmission electron microscope. Samples were prepared by directly depositing the sonicated GaSe-nanosheet/methanol solution onto a lacey carbon copper grid. The resolution of the instrument was 0.25 nm in TEM mode and 0.18 nm in scanning transmission electron microscopy mode with high angular annular diffraction (STEM-HAAD) mode for elemental analysis. Energy-dispersive X-ray (EDX) spectroscopy was conducted to analyze the sample’s chemical composition.−6 Torr at room temperature. A Xenon lamp was used as broad-band light source for preliminary tests and a 532 nm laser was used for detailed dynamic photoresponse measurements. The laser spot of 1.5 mm in diameter provided a uniform illumination over the GFET channel region. The power intensity was tuned using a continuously variable neutral density filter and calibrated using a Coherent FieldMaxII power meter with OP-2 probe. Electrical current noise spectra across the GFET channel were characterized by measuring the noise fluctuation on a resistor in serial with the GFET using a Stanford Research SR760 spectrum analyzer while keeping the required source-drain voltage across GFET channel.The back-gated field effect transport properties were characterized using an Agilent B1505A semiconductor device analyzer in a high-vacuum probe station of <2 × 10How to cite this article: Lu, R. et al. Graphene/GaSe-Nanosheet Hybrid: Towards High Gain and Fast Photoresponse. Sci. Rep.6, 19161; doi: 10.1038/srep19161 (2016).


The as-synthesized graphene with incorporation of nitrogen groups possesses unique structure including thin layer thickness, high surface area, mesopores and vacancies. These structural features and their synergistic effects could not only improve ions and electrons transportation with nanometer-scale diffusion distances but also promote the penetration of electrolyte. The N-doped graphene exhibits high reversible capacity, superior rate capability as well as long-term cycling stability, which demonstrate that the N-doped graphene with great potential to be an efficient electrode material. The experimental results provide a new hydrothermal route to synthesize N-doped graphene with potential application for advanced energy storage, as well as useful information to design new graphene materials.Nitrogen-doped (N-doped) graphene has been prepared by a simple one-step hydrothermal approach using hexamethylenetetramine (HMTA) as single carbon and nitrogen source. In this hydrothermal process, HMTA pyrolyzes at high temperature and the N-doped graphene subsequently self-assembles on the surface of MgO particles (formed by the Mg powder reacting with H In the past decade, graphene has attracted wide attentions due to its fascinating characters and broad applications13622s22p3)3 is the next element to carbon (1s22s22p2) in the periodic table with only one less valence electron, which possesses higher electronegativity of N (χ = 3.04) than that of C (χ = 2.55). The doping of N would create polarization in the sp2 carbon network, thereby further influence the chemical and physical properties of graphene. Previous reports demonstrated that N doping is efficient in tuning the characters of graphene materials: the bandgap opening and charge-carrier concentration could be induced by only 0.4 at% doping of graphitic N1015Nitrogen (1s3 and nitric acid)2328To date, N-doped graphene materials can be obtained by various methods including plasma method212O). During this in-situ approach, graphene synthesis and nitrogen doping are simultaneously achieved. The as-synthesized graphene with nitrogen-containing functional groups possesses an average thickness of 4–10 nm with interconnected mesoporous system. The high surface area, mesopores and vacancies of the N-doped graphene are particularly beneficial for the reversibly storage of lithium ions. These structural features and their synergistic effects would promote ions and electrons transportation with nanometer-scale diffusion distances as well as be favorable to the penetration of electrolyte. Extensive research carried out on lithium ion batteries demonstrate that the N-doped graphene electrode exhibits high reversible capacity, superior rate capability as well as long-term cycling stability , which suggest its great potential to be an efficient electrode material candidate.In this paper, we developed a novel one-step hydrothermal method using HMTA as single carbon and nitrogen source. Briefly, HMTA pyrolyzes in high temperature and the N-doped graphene subsequently self-assembles on the surface of MgO particles 2 and release small molecules sp2 carbon clusterssp2 clusters may assemble into polyaromatic systems and finally into graphene. A variety of nitrogen atoms would residue from the precursors after the whole hydrolyzation and graphitization process; the attachment of the sp2 carbons to the remaining nitrogen atoms preserves the sp2 hybridization state in HMTA. 002) of the sample are about 0.34 nm, which is slightly larger than the d002 spacing of graphite (d002 = 0.335 nm)Structural characterization of the as-prepared sample was carried out by the powder X-ray diffraction (XRD). The morphology and microstructure of as-prepared samples were imaged by SEM tests. 2O and HMTA to obtain MgO and the MgO would agglomerate into clusters. Then, the MgO clusters would act as structural constructor, and the curled and overlapped nanosheets are synthesized on the surface of the MgO clusters. When the samples are washed by HCl, the two-dimensional structure of graphene is well maintained and the nanosheets reveal a curled morphology consisting of a thin crumpled paper-like structure.The formation process of the graphene nanosheets based on a solution-growth pathway could be deduced from the SEM images . Firstly002 spacing) is measured to be about 0.34 nm, which is larger than that of graphite (0.335 nm) and agreed with the interlayer spacing calculated by XRD pattern. It is worth noting that the basal planes are discontinuous and distorted, and some parts are wavy and turbostratic, indicating that the layer stacking is disordered−1 and 1586 cm−1, which could be ascribed to the well-documented D and G band2g mode corresponds to ordered sp2 bonded carbon and provides the formation of graphitic carbon. The D band arises from the breathing modes of six-atom rings of κ-point phonons of A1g symmetry with defects for activation−1) is the D-band overtone41Raman spectra have sensitive response to the crystallinity, defects and disorder of microstructure of carbon materials37sp2 domains. The ratio of D to G band integrated intensities (ID/IG) is usually used to estimate the average crystallite size along the a-axis (La) of sp2 regions in the graphene layer. The La could be calculated by the empirical Tuinstra-Koenig equation: La = (2.4 × 10−10) λ4(ID/IG)−1 37D/IG is 1.13, so the crystallite size of ordered sp2 regions surrounded by areas of nitrogened carbon atoms or defects is about 14.9 nm. As a consequence, the Raman spectrum reveals that the N-doped graphene are composed of few-layered structure with sufficient defects which is crucial to improve its lithium diffusion and storage properties.The D, G and 2D bands of graphene2g−1, as well as the high volume of mesopores  method). The N-doped graphene exhibits a characteristic type IV isotherm with a pronounced hysteresis at P/P0 = 0.4–0.8 between the adsorption and desorption branches, suggesting the existence of a large number of mesopores with uniform pore size distribution0 = 0.45) is significantly delayed comparing with the capillary condensation. This delay process2 condensed in the pore interiors to the exterior when the N2 is condensed in the narrower connecting pores0 = 0.4. In this case, the ink bottle-like pore networks account for the occurrence of broad hysteresis loops. Moreover, the adsorption and desorption branches do not close below P/P0 = 0.3, which indicates that chemical adsorption might occur in the mesopores; this chemical adsorption is irreversible so the adsorpted N2 could not be desorpted at lower pressure. The pore size distribution  . As show1 (0.7 V) and R2 (below 0.2 V) and two anodic peaks O1 (1.2 V) and O2 (0.2 V) during the first cycle. The R1 peak in the 1st cycle and disappeared in the following cycles could be assigned to the decomposition of the electrolyte and formation of solid electrolyte interphase (SEI) film on the surfaces of graphene in the first cycle2 peak and the counterpart anodic O2 peak could be attributed to Li ions insertion into the graphene layers1 peak indicated that the breaking of the bonds of the Li atom with the defects or other active sites during the charge processes takes place at high voltage+ produces good reversibility.+ of the first cycle begins at around 2.0 V vs. Li/Li+; the curve exhibits a slope plateau at 0.8 V which arises from the combination of Li ions adsorption on the structural defects in basal planes of the graphene layers and the formation of solid electrolyte interphase (SEI) film5856Galvanostatic charge/discharge of the sample was measured at a current rate of 100 mA/g in the potential range from 0.01 V to 3 V with Li foil as a counter electrode at room temperature (25 °C). s), resistance (R1) of the surface film formed on the electrodes and the contact problemsdl), charge-transfer resistance (Rct)D) related to the diffusion capacitance of lithium ions into the graphene electrodes1 = Ω and Rct = 2.738 Ω). In this case, the electrical conductive capability are improved, resulting in the high capacity and stable cycling performance.The above analysis well demonstrated that N-doped graphene is an excellent electrode material of Li-ion battery. To get further insight into the electrochemical process, electrochemical impedance spectroscopy (EIS) were carried out by three electrode system and the obtained Nyquist plots are presented in According to the above results, the significantly improved electrochemical performance of N-doped graphene get benefit from the unique structure by nitrogen doping61In summary, we have successfully prepared a new kind of N-doped graphene through a facile one-step hydrothermal approach. The as-synthesized graphene with incorporation of nitrogen groups possesses unique structure including high surface area, mesopores and vacancies, which is particularly important for the reversibly storage of lithium ions. The structural features and their synergistic effects could not only promote ions and electrons transportation with nanometer-scale diffusion distances but also benefit to the penetration of electrolyte. The N-doped graphene exhibits outstanding electrochemical properties such as high reversible capacity, superior rate capability as well as long-term cycling stability, which endow it great potential to be an efficient electrode material candidate, and the EIS test further indicates that the N-doped graphene is a good lithium ion battery. The experimental results provide a novel hydrothermal route to fabricate N-doped graphene material with potential application for advanced energy storage, as well as useful information to design new graphene materials for future applications.All reagents  were analytical purity and used without further purification.Details of a typical synthesis process are as follows: Hexamethylenetetramine , magnesium powder  and ultrapure water (3 mL) were added into a 20 ml stainless steel autoclave. The autoclave was sealed, put in an electric furnace, warmed up at a rate of 10 °C/min and maintained at 500 °C for 20 h, and was then cooled to room temperature naturally. The precipitate was filtered off, washed with distilled water, absolute ethanol, and hydrochloric acid solution (5 mol/L) for several times, and then dried in vacuum at 50 °C for 3 h.−1. The morphology of the graphene were observed using a JEOL JSM-6700F field emission scanning electron microscope (SEM) operated at 15 kV and Hitachi H7650 transmission electron microscope (TEM) operated at 100 kv. The high resolution images were recorded using a high resolution transmission electron microscope  operated at 200 kV. The surface areas of the sample were measured by TriStar II 3020  and calculated by N2 adsorption-desorption isotherms. The XPS tests were performed on a Thermo Scientific ESCALAB 250 X-ray photoelectronic spectrometer with a non-monochromated Mg Kα X-ray radiation as the excitation source. The Raman spectroscopy data were taken on a LABRAM-HR laser MicroRaman spectrometer with excitation wavelength of 514.5 nm (2.41 eV).The X-ray powder diffraction (XRD) measurements were carried out on a Bruker AXS D8 Advance X-ray diffractometer equipped with Cu Ka radiation (λ = 1.54182 Å) at a scanning rate of 10° min6 in ethylene carbonate/dimethyl carbonate (EC/DMC) with a volume ratio of 1:1. The galvanostatic charge/discharge tests were tested in the voltage range of 0.01–3.0 V using a computer-controlled multichannel battery test unit (LAND-CT2001A battery cycler) at room temperature. The typical cyclic voltammetry (CV) measurements were performed in the potential window of 0.01–3.0 V at a scanning rate of 0.1 mV/s on LK-2005A electrochemical workstation.The electrochemical performances were measured with CR2032 coin-type cells. The N-doped graphene acted as an anode electrode, and Li foil was used as a counter electrode. To prepare the working electrodes, the active materials (70 wt %) were mixed with Super P carbon black (20 wt %) and polyvinylidene fluoride (PVDF) (10 wt %). These materials were dissolved in N-methyl pyrrolidone (NMP) and ball milled for 5 hours at speed of 400 rpm to obtain uniform slurry. Then the slurry was coated on a Cu foil current collector and subsequently dried under vacuum at 80 °C for 12 h. The Celgard 2300 microporous membrane was used as polypropylene separator, and the electrolyte was a 1 mol/L solution of LiPFHow to cite this article: Xing, Z. et al. One-pot hydrothermal synthesis of Nitrogen-doped graphene as high-performance anode materials for lithium ion batteries. Sci. Rep.6, 26146; doi: 10.1038/srep26146 (2016).


We provide a comprehensive picture of magnetotransport in graphene monolayers in the limit of nonquantizing magnetic fields. We discuss the effects of two-carrier transport, weak localization, weak antilocalization, and strong localization for graphene devices of various mobilities, through theory, experiments, and numerical simulations. In particular, we observe a minimum in the weak localization and strong localization length reminiscent of the minimum in the conductivity, which allows us to make the connection between weak and strong localization. This provides a unified framework for both localizations, which explains the observed experimental features. We compare these results to numerical simulation and find a remarkable agreement between theory, experiment, and numerics. Various graphene devices were used in this study, including graphene on different substrates, such as glass and silicon, as well as low and high mobility devices. This square root dependence leads to a very large lowest Landau level splitting, where the field quantization has been observed up to room temperature [Graphene has attracted a considerable amount of attention due to the ease in isolating a single sheet of graphite via mechanical exfoliation , 2. Despperature . While tμqB ≪ 1, where μq is the quantum mobility. In this regime, the Landau quantization does not play any role, but the valley degeneracy, the linear dispersion, and the underlying disorder potential lead to interesting magnetotransport phenomena such as two-carrier transport (2CT), weak localization (WL), weak antilocalization (WAL), and strong localization (SL).The goal of this work is to present a comprehensive understanding of the magnetoresistance of monolayer graphene in a regime where the Landau quantization is not important; that is, τe−1, and intravalley scattering, where electrons scatter within a valley as described by a rate τa−1. In general, intervalley stems from short range scattering, such as atomic defects, including grain boundaries, whereas intravalley scattering is long range and is typically stronger and also includes large scale inhomogeneities and charged impurities in the substrate. Long range potential variations are responsible for the existence of both carriers' types (electrons and holes) simultaneously at the charge neutrality point (CNP). The carrier distribution can be understood by assuming that the total carrier density is given by n − p = C|VG − VD|/e, C is the gate capacitance, VG the gate voltage, and VD the gate voltage at the charge neutrality point (CNP) with a total residual density n0 . n0 is composed of the thermal carriers plus remaining electrons and holes due to sample inhomogeneities as a consequence of the underlying disorder potential. This disorder induced residual density dominates at low temperatures. n and p are the carrier densities of electrons and holes, respectively. This allows us to define electron and hole mobilities, μn = σn/en and μp = σp/ep, where σn and σp are the corresponding electron and hole conductivities. Experimentally, μn and μp are often slightly different, which is likely due to the asymmetry of the scattering potential for electrons and holes.Most of the magnetotransport properties of graphene can be understood in terms of two types of scattering mechanisms: intervalley scattering, where electrons are scattered from one valley to the other (K to K′) with a rate hereby noted as 2+(n-p)2 , where nDorgan's  work, nμqB ≪ 1, this contribution can be evaluated using Drude's expression for two carriers, where ρxxη = ση−1 and ρxyη = sign(qη)B/eη for the two types of carrier densities (η = n or p). The total resistivity is then given by We start our magnetotransport analysis by discussing the simplest nontrivial contribution, which is due to the simultaneous existence of the two types of carriers near the CNP. As long as ρxx = (σn+σp)−1, and identifying ρmax as the zero field resistivity at the CNP, we obtainExpressing the conductivities in  in termsB the 2CT gives rise to a parabolic positive relative magnetoresistance before saturating to n0/|n − p| when B≃B1, which is valid as long as μqB ≪ 1. Close to the CNP, that is, |n − p | ≪n0, B0 is simply equal to the inverse median mobility and B1 ≫ B0, which is the regime where the 2CT effect is the largest. Away from the CNP (|n − p| ≫ n0), we have a maximum Δρ/ρ≃n0/nH, which decreases away from the CNP, since nH≃|n − p|, which is the Hall density, increases. The 2CT will play an important role, as long as μqB ≪ 1, to give rise to positive magnetoresistance due to large scale inhomogeneities. This effect is very important in graphene as compared to other two-dimensional systems because of the absence of a gap between the electron and hole carriers. The 2CT will serve as basis for the understanding of the classical contribution due to long range scattering, which will be present at all temperatures and even increases with temperature, since n0 increases with temperature due to the thermal activation of the electron and hole carriers.Hence, as a function of Pret can be expressed as [πDt)−1 in the integrant is the return probability (P0(t)) for diffusion constant D, the second term represents the short time cut-off (τe), below which no elastic scattering occurs, and the third term is the phase coherence time (τϕ) cut-off, beyond which phase coherence is lost. At low temperatures, where τϕ ≫ τe, this leads to the typical logarithmic WL correction of the conductivity δσ = −(4e2D/h)Pret≃−(e2/πh)ln(τϕ/τe).Moving beyond the Drude and classical description of transport, we need to include quantum effects, of which coherent backscattering is the most important contribution. Coherent backscattering leads to WL , 10. To essed as (5)Pret=PB(t), we have to solve for the return probability according to the field dependent diffusion equation [A is the vector potential. The solution to this diffusion equation can be evaluated for r = r′ and is given byτB = ħ/4eBD. At zero field we recover P0(t). In the long time limit, where we have PB(t)→(eB/h)et/2τB−, this leads to the field induced destruction of the phase coherence when approximately one flux penetrates the area LB2 = DτB. The full magnetic field dependence is obtained by inserting PB(t) into the expression of the coherent return probability and evaluating the integral; that is,Bϕ = ħ/4eDτϕ and Be = ħ/4eDτe are the characteristic magnetic fields for τϕ and τe, whereas ψ is the digamma function. The magnetic field correction to the coherent return probability is then given byF(z) = ψ(1/2 + 1/z) + ln(z), F(z)≃z2/24 for z ≪ 1, F(z)≃ln(1 + z/4eγ) for z ≫ 1, and γ is the Euler constant. The second term in  = ln(Bϕ/(Bϕ + Be)). This expression leads to the usual WL correction to the conductivity when expressing the conductivity correction in terms of the coherent return probability correction; that is, Δσ = −4e2DΔPret/h [To evaluate the magnetic field dependence of the return probability equation :(6)[∂∂tgiven byΔPret=Pre systems . The firΔPret/h , 14.τϕ (phase breaking) and τe (elastic). However, in graphene, we have two very different types of elastic scattering mechanisms: those that scatter electrons within a valley  and those that scatter between valleys . Here only intervalley scattering contributes to coherent backscattering; hence, the short time cut-off scattering time is provided by τe in graphene. Intervalley scattering is typically induced by short ranged impurities and can be due to grain boundaries or lattice defects. However, intravalley scattering is usually much stronger in graphene but does not contribute to coherent backscattering.In deriving  we assumB involving the scattering parameters τa and τe explicitly. They obtained the following expression:B⋆ = Ba + Be/2 and τ⋆ = ħ/4eDB⋆. This expression can also be obtained directly using (et/τe− in the magnetic field correction by (et/τe− + 2et/τ⋆−). While the first two terms in , where σ0 is related to the quantum conductance. For small corrections in the conductivity, this expression yields δLc/Lc≃δσ/σ0. However, for strong disorder this expression is not valid and we will evaluate Lc numerically below.Equation  tells usimension , which wimension , as Lc Lϕ > W and W is the width of the graphene ribbon. In this limit, the governing diffusion equation is no longer 2D but has to be replaced by the 1D analogue; that is, τb is given as usual by Lb2/D, where WLb [In many situations, both experimentally and numerically, one deals with a situation where the sample width is finite. This leads to a different field dependence, since the sample effectively becomes quasi-one-dimensional (Q1D) instead of 2D, when t)e-t/τb , where trea WLb . This leτe−1 ≫ τϕ−1 + τb−1 we obtain the following expression for the magnetic field correction of the coherent return probability:When σ = −4e2DΔPret/h, we recover the expression for the WL correction to the conductivity obtained by McCann and coworkers [Recalling that Δoworkers .τc, which has the effect of simply replacing 1/Lϕ2 by 1/Lcϕ2 = 1/Lϕ2 + 1/Lc2. We then obtain for the relative change in the coherent return probabilityBW = ħ/4eW2. This is the result for the Q1D limit, when Lϕ or Lc≫W. Here again we have ΔLc/Lc≃−ΔPret/Pret|Bϕ=0 for the relative change of the localization length.For the strong disorder case, we have to again introduce the localization time Lc numerically for graphene assuming that Lϕ ≫ Lc, W. There are two different limits: 2D and Q1D; that is, Lc ≪ W (the high disorder limit) and Lc ≫ W (the low disorder limit), respectively. These two limits are mainly determined by the amount of disorder in the system. For the numerical simulations, we will only consider short ranged disorder, since this is the relevant source for WL. The effect of long range disorder is to induce the coexistence of electrons and holes close to the charge neutrality point as well as WAL.We now move to evaluate t≃3 eV. The two ends of the graphene device are assumed to be connected to wide ohmic contacts with a quadratic dispersion. The short range disorder is implemented by adding a random onsite potential vi on every atom site uniformly distributed with −V/2 < vi < V/2. The magnetic field is simply a phase factor ϕ in the hopping term, where 2πϕ = 1 corresponds to one flux quantum in a hexagon. The two-terminal transmission probability T is then evaluated iteratively as a function of the length, L, of the system, using an efficient iterative Green's function method [T(L)〉e2/h, resistance 〈1/T(L)〉h/e2, or logarithm conductance 〈ln(T(L))〉 is obtained by averaging over many disorder configurations (〈·〉). For a given W and at large enough L, the system is always localized due to Anderson localization and Lc can be extracted whenever L ≫ Lc.To model the system accurately, we consider a tight binding model with a honeycomb structure with two types of edges: armchair and zigzag. The hopping term is given by n method . Similarn method , 24. TheLc with the analytical expressions derived above for the relative change in Lc, that is, testing  → L/Lc. Therefore, small variations in Lc lead to ΔRxx/Rxx≃−LΔLc/Lc2. This is assuming that Lϕ ≫ L. However, in experiments, where this is often not the case, Lϕ plays the role of effective sample size (Lϕ = L) so that when Lϕ ≪ L we can write ΔRxx/Rxx≃−LϕΔLc/Lc2 instead. This is often used in experiments to extract Lc from the temperature dependence of the resistance, since Lϕ also depends on temperature [Lϕ is constant, but Lc is magnetic field dependent. Hence, when Lϕ ≪ L we have, using ΔRxR/R ≪ 1), different contributions to the resistance are additive; hence the total effect on the resistance, including the two-carrier effect, yieldsLc−2 + Lϕ−2 = 4eBcϕ/ħ, Le−2 = 4eBe/ħ, B0≃ρmax/μρxx, and B1≃B0n0/nH.For small variations (Δμm) single crystal graphene. Monolayers of graphene were grown by chemical vapor deposition (CVD) of hydrocarbons on 25 μm thick commercial Cu foils. The CVD process used was similar to those described in previous works [While WL was observed in graphene in a number of previous experiments –29 and fus works –33.Lϕ≃50 nm and Lc≃120 nm, which shows that the localization length is of the same order of magnitude as the phase coherence length. The agreement between the fit and the data is quite remarkable over the entire available magnetic field range and only relies on three fitting parameters, in this case Bcϕ, Be, and Lϕ/Lc. The other parameters B0 and B1 are too large to significantly affect the fit. For even higher disorder, we expect Lc to be smaller than Lϕ and we would need to modify our assumption of the linear approximation used in (Lc(B) and its associated field dependence. This is amplified further for long but narrow samples (nanoribbons).We start with low mobility samples, which cannot be fitted with the standard WL theory  alone be used in . InsteadLϕ≃220 nm, Lc≃2.3 μm, and Le≃4.3 nm. Here again, the agreement between the fit and the data is quite remarkable, considering that the fit extends over the entire magnetic field range.The next step is to look at a large scale (~cm) graphene sample grown by CVD deposited on a glass slide with evaporated gold as contacts. The magnetic field dependence is shown in 2/Si substrate, where the doped silicon can be used as a back gate. The main difference is that this sample was grown using isotopically pure C13 methane gas instead of C12, so that the Raman peaks are shifted by Lϕ≃330 nm, Lc≃6 μm, Le≃120 nm, and a mean field effect mobility of μ≃0.18 m2/Vs, which is common for large scale CVD graphene, and a residual density of n0≃7.0 × 1011 cm−2.The next sample we are considering is a large scale (~cm) sized graphene sample grown by CVD and deposited on a standard SiOby 12/13 . Howevern and p type carriers. Strikingly, the quality of the fit is very remarkable over the entire available experimental magnetic field range.Interestingly, this is a prime example of a large parabolic-like positive magnetoresistance background, which cannot be fitted using WAL as per , since Wμm diameter) single graphene crystal grown by CVD [μn≃0.43 m2/Vs for electrons and μp≃0.63 m2/Vs for holes. The CNP was at VG = 5.4 V. Using ≃9 and found a remarkable agreement with the field effect mobility extracted from the gate voltage dependence. For the residual density we obtain n0≃5.8 × 1011 cm−2 using μ−1 = en0ρmax.We now turn to the higher mobility case, where we consider a graphene field effect device made out of a large , which all samples show, there is often a parabolic positive magnetoresistance which is mainly due to the 2CT effect because of large scale inhomogeneities in addition to WAL in very clean samples.The overall experimental behavior can be summarized as follows: at low temperatures, very low mobility samples show a very wide peak in the resistance at zero field  and from the presence of two types of carriers close to the CNP (the 2CT). While WL is generic to all disordered systems, both WAL and 2CT are specific to graphene, where both play an important role in the understanding of magnetotransport.