Long-term stabilization of two-dimensional perovskites by encapsulation with hexagonal boron nitride

Metal halide perovskites are known to suffer from rapid degradation, limiting their direct applicability. Here, the degradation of phenethylammonium lead iodide (PEA2 PbI4) two-dimensional perovskites under ambient conditions was studied using fluorescence, absorbance, and fluorescence lifetime measurements. It was demonstrated that the long-term stability of two-dimensional perovskites could be achieved through the encapsulation with hexagonal boron nitride. While un-encapsulated perovskite flakes degraded within hours, the encapsulated perovskites were stable for at least three months. In addition, encapsulation considerably improved the stability under laser irradiation. The environmental stability, combined with the improved durability under illumination, is a critical ingredient for thorough spectroscopic studies of the intrinsic optoelectronic properties of this material platformMS acknowledges the financial support of a fellowship from ”la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/IN17/11620040. MS has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 713673. FP acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through The “María de Maeztu” Program for Units of Excellence in R and D (MDM-2014-0377) and the Comunidad de Madrid Talent Program for Experienced Researchers (2016-T1/IND-1209). ACG acknowledges financial support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement n◦ 755655, ERC-StG 2017 project 2D-TOPSENSE) and EU Graphene Flagship funding (Grant Graphene Core 2, 785219

Fatigue related impairments in oculomotor control are prevented by caffeine

Strenuous exercise can result in an inability of the central nervous system to drive skeletal muscle e ectively, a phenomenon known as central fatigue. The impact of central fatigue on the oculomotor system is currently unexplored. Fatigue that originates in the central nervous system may be related to perturbations in the synthesis and metabolism of several neurotransmitters. In this study we examine central fatigue in the oculomotor system after prolonged exercise. The involvement of central neurotransmission was explored by administering ca eine during exercise. Within a double- blind, randomized, repeated measures, crossover design, 11 cyclists consumed a placebo or ca eine solution during 180 min of stationary cycling. Saccadic eye movements were measured using infra-red oculography. Exercise decreased saccade velocity by 8% (placebo trial). This e ect was reversed by ca eine, whereby velocity was increased by 11% after exercise. A non oculomotor perceptual task (global motion processing) was una ected by exercise. The human oculomotor system is impaired by strenuous exercise of the locomotor system. Ca eine exerts a protective e ect on oculomotor control, which could be related to up-regulated central neurotransmission. In addition, cortical processes supporting global motion perception appear to be robust to fatigue

A system for the deterministic transfer of 2D materials under inert environmental conditions

The isolation of air-sensitive two-dimensional (2D) materials and the race to achieve a better control of the interfaces in van der Waals heterostructures has pushed the scientific community towards the development of experimental setups that allow to exfoliate and transfer 2D materials under inert atmospheric conditions. These systems are typically based on over pressurized N2 of Ar gloveboxes that require the use of very thick gloves to operate within the chamber or the implementation of several motorized micro-manipulators. Here, we set up a deterministic transfer system for 2D materials within a gloveless anaerobic chamber. Unlike other setups based on over-pressurized gloveboxes, in our system the operator can manipulate the 2D materials within the chamber with bare hands. This experimental setup allows us to exfoliate 2D materials and to deterministically place them at a desired location with accuracy in a controlled O2-free and very low humidity (<2% RH) atmosphere. We illustrate the potential of this system to work with air-sensitive 2D materials by comparing the stability of black phosphorus and perovskite flakes inside and outside the anaerobic chamberThis project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement n° 755655, ERC-StG 2017 project 2D-TOPSENSE). EU Graphene Flagship funding (Grant Graphene Core 2, 785219) is acknowledged. RF acknowledges the support from the Spanish Ministry of Economy, Industry and Competitiveness through a Juan de la Cierva-formación fellowship 2017 FJCI2017-32919. QHZ acknowledges the grant from China Scholarship Council (CSC) under No. 201700290035. MS acknowledges the financial support of a fellowship from ‘la Caixa’ Foundation (ID 100010434). The fellowship code is LCF/BQ/IN17/11620040. MS has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 713673. FP acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through the ‘María de Maeztu’ Program for Units of Excellence in R and D (MDM-2014-0377

Thickness-Dependent Differential Reflectance Spectra of Monolayer and Few-Layer MoS2, MoSe2, WS2 and WSe2

The research field of two dimensional (2D) materials strongly relies on optical microscopy characterization tools to identify atomically thin materials and to determine their number of layers. Moreover, optical microscopy-based techniques opened the door to study the optical properties of these nanomaterials. We presented a comprehensive study of the differential reflectance spectra of 2D semiconducting transition metal dichalcogenides (TMDCs), MoS2, MoSe2, WS2, and WSe2, with thickness ranging from one layer up to six layers. We analyzed the thickness-dependent energy of the different excitonic features, indicating the change in the band structure of the different TMDC materials with the number of layers. Our work provided a route to employ differential reflectance spectroscopy for determining the number of layers of MoS2, MoSe2, WS2, and WSe2.Comment: Main text (3 Figures) and Supp. Info. (23 Figures

Mapping of modifiable barriers and facilitators of medication adherence in bipolar disorder to the Theoretical Domains Framework: a systematic review protocol

Introduction: People with bipolar disorder require long-term treatment but it is estimated that 40% of these people do not adhere to prescribed medication regimens. Non-adherence increases the risk of relapse, hospitalisation and suicide. Some evidence syntheses report barriers to mental health treatment adherence but rarely delineate between modifiable and non-modifiable barriers. They also fail to distinguish between the patients’ perspective and that of other stakeholders such as clinicians despite of their different understanding and priorities about adherence. Facilitators of adherence, which are also important for informing adherence intervention design, are also lacking from syntheses and few syntheses focus on medications for bipolar disorder. This systematic review aims to identify modifiable barriers and facilitators (determinants) of medication adherence in bipolar disorder. We also plan to report determinants of medication adherence from perspectives of patients, carers, healthcare professionals and other third parties. A unique feature of this systematic review in the context of mental health is the use of the Theoretical Domains Framework (TDF) to organise the literature identified determinants of medication adherence. Methods and analysis: The protocol adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols and ENhancing Transparency in REporting the synthesis of Qualitative research (ENTREQ) guidelines. This review will include both qualitative and quantitative primary studies exploring determinants of medication adherence in bipolar disorder. We will search the following databases using a preplanned strategy: CINAHL, Cochrane Library (CENTRAL), Embase, LiLACS, Medline, PsychINFO, PubMed without date restrictions. We will report the quality of included studies. We will use framework synthesis using the TDF as an a priori ‘framework’. We will map the literature identified modifiable determinants to the domains of TDF. Ethics and dissemination: Ethical approval is not required as primary data will not be collected. The results will be disseminated through a peer-reviewed publication. PROSPERO registration number:CRD42018096306

Circadian Cycling of the Mouse Liver Transcriptome, as Revealed by cDNA Microarray, Is Driven by the Suprachiasmatic Nucleus

AbstractBackground: Genes encoding the circadian pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) of mammals have recently been identified, but the molecular basis of circadian timing in peripheral tissue is not well understood. We used a custom-made cDNA microarray to identify mouse liver transcripts that show circadian cycles of abundance under constant conditions.Results: Using two independent tissue sampling and hybridization regimes, we show that ∼9% of the 2122 genes studied show robust circadian cycling in the liver. These transcripts were categorized by their phase of abundance, defining clusters of day- and night-related genes, and also by the function of their products. Circadian regulation of genes was tissue specific, insofar as novel rhythmic liver genes were not necessarily rhythmic in the brain, even when expressed in the SCN. The rhythmic transcriptome in the periphery is, nevertheless, dependent on the SCN because surgical ablation of the SCN severely dampened or destroyed completely the cyclical expression of both canonical circadian genes and novel genes identified by microarray analysis.Conclusions: Temporally complex, circadian programming of the transcriptome in a peripheral organ is imposed across a wide range of core cellular functions and is dependent on an interaction between intrinsic, tissue-specific factors and extrinsic regulation by the SCN central pacemaker

Effect of UVA Fluence Rate on Indicators of Oxidative Stress in Human Dermal Fibroblasts

During the course of a day human skin is exposed to solar UV radiation that fluctuates in fluence rate within the UVA (290-315 nm) and UVB (315-400 nm) spectrum. Variables affecting the fluence rate reaching skin cells include differences in UVA and UVB penetrating ability, presence or absence of sunscreens, atmospheric conditions, and season and geographical location where the exposure occurs. Our study determined the effect of UVA fluence rate in solar-simulated (SSR) and tanning-bed radiation (TBR) on four indicators of oxidative stress---protein oxidation, glutathione, heme oxygenase-1, and reactive oxygen species--in human dermal fibroblasts after receiving equivalent UVA and UVB doses. Our results show that the higher UVA fluence rate in TBR increases the level of all four indicators of oxidative stress. In sequential exposures when cells are exposed first to SSR, the lower UVA fluence rate in SSR induces a protective response that protects against oxidative stress following a second exposure to a higher UVA fluence rate. Our studies underscore the important role of UVA fluence rate in determining how human skin cells respond to a given dose of radiation containing both UVA and UVB radiation

Modelling ruptures of buried high pressure dense phase CO2 pipelines in carbon capture and storage applications - Part I. Validation

Carbon dioxide (CO2) capture and storage presents a short-term option for significantly reducing the amount of CO2 released into the atmosphere and mitigating the effects of climate change. To this end, National Grid initiated the COOLTRANS research programme to consider the pipeline transportation of high pressure dense phase CO2, including the development and application of a mathematical model for predicting the sonic near-field dispersion of pure CO2 following the venting or failure of such a pipeline. Here, the application of this model to the rupture of a buried pipeline is considered and compared to experimental data obtained through the COOLTRANS programme. The rupture experiment was performed on a 230 m length of 152 mm external diameter pipeline with 300 mm soil cover, equivalent to approximately 1/4 scale when compared to the proposed full-scale 600 mm (24-inch) diameter pipelines with 1.2 m soil cover on average proposed in the UK. The experiment was performed in a pre-formed crater based on experimentally formed craters in other experiments. The comparison demonstrates reasonable quantitative and qualitative agreement. Such validated dispersion flow, to be applied to full-scale rupture modelling in Part II, defines novel, robust, thermodynamically accurate multi-phase source conditions, that enable far-field computational fluid dynamics studies and feed into pragmatic quantified risk assessment models

High pressure CO2 CCS pipelines: Comparing dispersion models with multiple experimental datasets

Carbon capture and storage (CCS) presents the short-term option for significantly reducing the amount of carbon dioxide (CO2) released into the atmosphere from the combustion of fossil fuels, thereby mitigating the effects of climate change. Enabling CCS requires the development of capture, storage and transport methodologies. The safe transport of CO2 in CCS scenarios can be achieved through pipelines or by shipping. Either way, transport and temporary storage of pressurised liquid CO2 will be required and subject to quantitative risk assessment, which includes the consideration of the low-risk, low-probability puncture or rupture scenario of such a pipeline, ship or storage facility. In this work, we combine multiple experimental datasets all concerned with the atmospheric free release of pure and impure liquid CO2 from CCS-transport-chain-relevant high pressure reservoirs and perform the first multiple dataset comparison to numerical models for both pure and impure jets in dry ambient air with no water vapour. The results validate the numerical approach adopted and for the prediction of such releases, highlight the significance of the mixture fraction at the release point, over the mixture composition itself. A new method for impure CO2 dispersion modelling is introduced and limited preliminary comparisons of impure CO2 data and predictions are performed. No clear difference between pure and impure releases is found for the cases considered