Transfer of Large-Scale Two-Dimensional Semiconductors:Challenges and Developments

Two-dimensional (2D) materials offer opportunities to explore both fundamental science and applications in the limit of atomic thickness. Beyond the prototypical case of graphene, other 2D materials have recently come to the fore. Of particular technological interest are 2D semiconductors, of which the family of materials known as the group-VI transition metal dichalcogenides (TMDs) has attracted much attention. The presence of a bandgap allows for the fabrication of high on-off ratio transistors and optoelectronic devices, as well as valley/spin polarized transport. The technique of chemical vapour deposition (CVD) has produced high-quality and contiguous wafer-scale 2D films, however, they often need to be transferred to arbitrary substrates for further investigation. In this Review, the various transfer techniques developed for transferring 2D films will be outlined and compared, with particular emphasis given to CVD-grown TMDs. Each technique suffers undesirable process-related drawbacks such as bubbles, residue or wrinkles, which can degrade device performance by for instance reducing electron mobility. This Review aims to address these problems and provide a systematic overview of key methods to characterize and improve the quality of the transferred films and heterostructures. With the maturing technological status of CVD-grown 2D materials, a robust transfer toolbox is vital

T-lymphocyte Tyrosine Hydroxylase Regulates T H 17 T-lymphocytes During Repeated Social Defeat Stress

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder which results in deleterious changes to psychological and physical health. Patients with PTSD are especially susceptible to life-threatening co-morbid inflammation-driven pathologies, such as autoimmunity, while also demonstrating increased T-helper 17 (TH17) lymphocyte-driven inflammation. While the exact mechanism of this increased inflammation is unknown, overactivity of the sympathetic nervous system is a hallmark of PTSD. Neurotransmitters of the sympathetic nervous system (i.e., catecholamines) can alter T-lymphocyte function, which we have previously demonstrated to be partially mitochondrial redox-mediated. Furthermore, we have previously elucidated that T-lymphocytes generate their own catecholamines, and strong associations exist between tyrosine hydroxylase (TH; the rate-limiting enzyme in the synthesis of catecholamines) and pro-inflammatory interleukin 17A (IL-17A) expression within purified T-lymphocytes in a rodent model of psychological trauma. Therefore, we hypothesized that T-lymphocyte-generated catecholamines drive TH17 T-lymphocyte polarization through a mitochondrial superoxide-dependent mechanism during psychological trauma. To test this, T-lymphocyte-specific TH knockout mice (THT-KO) were subjected to psychological trauma utilizing repeated social defeat stress (RSDS). RSDS characteristically increased tumor necrosis factor-α (TNFα), IL-6, IL-17A, and IL-22, however, IL-17A and IL-22 (TH17 produced cytokines) were selectively attenuated in circulation and in T-lymphocytes of THT-KO animals. When activated ex vivo, secretion of IL-17A and IL-22 by THT-KO T-lymphocytes was also found to be reduced, but could be partially rescued with supplementation of norepinephrine specifically. Interestingly, THT-KO T-lymphocytes were still able to polarize to TH17 under exogenous polarizing conditions. Last, contrary to our hypothesis, we found RSDS-exposed THT-KO T-lymphocytes still displayed elevated mitochondrial superoxide, suggesting increased mitochondrial superoxide is upstream of T-lymphocyte TH induction, activity, and TH17 regulation. Overall, these data demonstrate TH in T-lymphocytes plays a critical role in RSDS-induced TH17 T-lymphocytes and offer a previously undescribed regulator of inflammation in RSDS

A study on the inclusion of forest canopy morphology data in numerical simulations for the purpose of wind resource assessment

A series of numerical simulations of the flow over a forest stand have been conducted using two different turbulence closure models along with various levels of canopy morphology data. Simulations have been validated against Stereoscopic Particle Image Velocimetry measurements from a wind tunnel study using one hundred architectural model trees, the porosities of which have been assessed using a photographic technique. It has been found that an accurate assessment of the porosity of the canopy, and specifically the variability with height, improves simulation quality regardless of the turbulence closure model used or the level of canopy geometry included. The observed flow field and recovery of the wake is in line with characteristic canopy flows published in the literature and it was found that the shear stress transport turbulence model was best able to capture this detail numerically

Effect of distillers grains moisture and inclusion level in livestock diets on greenhouse gas emissions in the corn-ethanol-livestock life cycle

A model was previously developed (Biofuel Energy Systems Simulator; www. bess.unl.edu) to predict greenhouse gas (GHG) emissions and net energy yield when ethanol is produced from corn. The model also predicts feedlot cattle, dairy cattle, and swine performance and feed replacement value of ethanol coproducts. Updated equations that predict performance of feedlot cattle fed 0 to 40% of dietary DM as corn wet (WDGS), modified (MDGS), or dry (DDGS) distillers grains plus solubles replacing dry-rolled and high-moisture corn were developed and incorporated into the model. Equations were derived from pen-level performance for 20 finishing studies evaluating WDGS, 4 evaluating MDGS, and 4 evaluating DDGS conducted at the University of Nebraska. Feeding value of WDGS was 145 to 131% of corn replaced when included at 20 to 40% of diet DM due to a quadratic (P \u3c 0.01) increase in G:F. The feeding value of MDGS was 124 to 117% with a quadratic (P \u3c 0.01) increase in G:F and 112 to 110% for DDGS with a linear (P \u3c 0.01) increase in G:F. Midwest corn-ethanol-livestock life cycle GHG reduction relative to gasoline (97.7 g CO2 equivalent/MJ of ethanol) was 61 to 57% when WDGS was fed to feedlot cattle for 20 to 40% diet inclusion. Feeding MDGS and DDGS to feedlot cattle reduced GHG emissions from the corn-ethanol-cattle system by 53 to 50% and 46 to 41%, respectively. Feeding WDGS to feedlot cattle was the optimum feed use of distillers grains plus solubles based on feeding performance and GHG reduction

Estimating the probability of demonstrating vaccine efficacy in the declining Ebola epidemic: a Bayesian modelling approach.

OBJECTIVES: We investigate the chance of demonstrating Ebola vaccine efficacy in an individually randomised controlled trial implemented in the declining epidemic of Forécariah prefecture, Guinea. METHODS: We extend a previously published dynamic transmission model to include a simulated individually randomised controlled trial of 100,000 participants. Using Bayesian methods, we fit the model to Ebola case incidence before a trial and forecast the expected dynamics until disease elimination. We simulate trials under these forecasts and test potential start dates and rollout schemes to assess power to detect efficacy, and bias in vaccine efficacy estimates that may be introduced. RESULTS: Under realistic assumptions, we found that a trial of 100,000 participants starting after 1 August had less than 5% chance of having enough cases to detect vaccine efficacy. In particular, gradual recruitment precludes detection of vaccine efficacy because the epidemic is likely to go extinct before enough participants are recruited. Exclusion of early cases in either arm of the trial creates bias in vaccine efficacy estimates. CONCLUSIONS: The very low Ebola virus disease incidence in Forécariah prefecture means any individually randomised controlled trial implemented there is unlikely to be successful, unless there is a substantial increase in the number of cases

Duration of Ebola virus RNA persistence in semen of survivors: population-level estimates and projections.

Ebola virus can persist in semen after recovery, potentially for months, which may impact the duration of enhanced surveillance required after interruption of transmission. We combined recent data on viral RNA persistence with weekly disease incidence to estimate the current number of semen-positive men in affected West African countries. We find the number is low, and since few reported sexual transmission events have occurred, the future risk is also likely low, although sexual health promotion remains critical

The Effect of Single Nucleotide Polymorphisms from Genome Wide Association Studies in Multiple Sclerosis on Gene Expression

BACKGROUND: Multiple sclerosis (MS) is a complex neurological disorder. Its aetiology involves both environmental and genetic factors. Recent genome-wide association studies have identified a number of single nucleotide polymorphisms (SNPs) associated with susceptibility to (MS). We investigated whether these genetic variations were associated with alteration in gene expression. METHODS/PRINCIPAL FINDINGS: We used a database of mRNA expression and genetic variation derived from immortalised peripheral lymphocytes to investigate polymorphisms associated with MS for correlation with gene expression. Several SNPs were found to be associated with changes in expression: in particular two with HLA-DQA1, HLA-DQA2, HLA-DQB1, HLA-DRB1, HLA-DRB4 and HLA-DRB5, one with ZFP57, one with CD58, two with IL7 and FAM164A, and one with FAM119B, TSFM and KUB3. We found minimal cross-over with a recent whole genome expression study in MS patients. DISCUSSION: We have shown that many susceptibility loci in MS are associated with changes in gene expression using an unbiased expression database. Several of these findings suggest novel gene candidates underlying the effects of MS-associated genetic variation

Optimisation of the Schizosaccharomyces pombe urg1 expression system

The ability to study protein function in vivo often relies on systems that regulate the presence and absence of the protein of interest. Two limitations for previously described transcriptional control systems that are used to regulate protein expression in fission yeast are: the time taken for inducing conditions to initiate transcription and the ability to achieve very low basal transcription in the "OFF-state". In previous work, we described a Cre recombination-mediated system that allows the rapid and efficient regulation of any gene of interest by the urg1 promoter, which has a dynamic range of approximately 75-fold and which is induced within 30-60 minutes of uracil addition. In this report we describe easy-to-use and versatile modules that can be exploited to significantly tune down P urg1 "OFF-levels" while maintaining an equivalent dynamic range. We also provide plasmids and tools for combining P urg1 transcriptional control with the auxin degron tag to help maintain a null-like phenotype. We demonstrate the utility of this system by improved regulation of HO-dependent site-specific DSB formation, by the regulation Rtf1-dependent replication fork arrest and by controlling Rhp18(Rad18)-dependent post replication repair