Mixed Cation Halide Perovskite under Environmental and Physical Stress

Despite the ideal performance demonstrated by mixed perovskite materials when used as active layers in photovoltaic devices, the factor which still hampers their use in real life remains the poor stability of their physico-chemical and functional properties when submitted to prolonged permanence in atmosphere, exposure to light and/or to moderately high temperature. We used high resolution photoelectron spectroscopy to compare the chemical state of triple cation, double halide Cs [Formula: see text] (FA [Formula: see text] MA [Formula: see text]) [Formula: see text] Pb(I [Formula: see text] Br [Formula: see text]) [Formula: see text] perovskite thin films being freshly deposited or kept for one month in the dark or in the light in environmental conditions. Important deviations from the nominal composition were found in the samples aged in the dark, which, however, did not show evident signs of oxidation and basically preserved their own electronic structures. Ageing in the light determined a dramatic material deterioration with heavily perturbed chemical composition also due to reactions of the perovskite components with surface contaminants, promoted by the exposure to visible radiation. We also investigated the implications that 2D MXene flakes, recently identified as effective perovskite additive to improve solar cell efficiency, might have on the labile resilience of the material to external agents. Our results exclude any deleterious MXene influence on the perovskite stability and, actually, might evidence a mild stabilizing effect for the fresh samples, which, if doped, exhibited a lower deviation from the expected stoichiometry with respect to the undoped sample. The evolution of the undoped perovskites under thermal stress was studied by heating the samples in UHV while monitoring in real time, simultaneously, the behaviour of four representative material elements. Moreover, we could reveal the occurrence of fast changes induced in the fresh material by the photon beam as well as the enhanced decomposition triggered by the concurrent X-ray irradiation and thermal heating

Precursors for cytochrome P450 profiling breath tests from an in silico screening approach

The family of cytochrome P450 enzymes (CYPs) is a major player in the metabolism of drugs and xenobiotics. Genetic polymorphisms and transcriptional regulation give a complex patient-individual CYP activity profile for each human being. Therefore, personalized medicine demands easy and non-invasive measurement of the CYP phenotype. Breath tests detect volatile organic compounds (VOCs) in the patients’ exhaled air after administration of a precursor molecule. CYP breath tests established for individual CYP isoforms are based on the detection of 13CO2 or 14CO2 originating from CYP-catalyzed oxidative degradation reactions of isotopically labeled precursors. We present an in silico work-flow aiming at the identification of novel precursor molecules, likely to result in VOCs other than CO2 upon oxidative degradation as we aim at label-free precursor molecules. The ligand-based work-flow comprises five parts: (1) CYP profiling was encoded as a decision tree based on 2D molecular descriptors derived from established models in the literature and validated against publicly available data extracted from the DrugBank. (2) Likely sites of metabolism were identified by reactivity and accessibility estimation for abstractable hydrogen radical. (3) Oxidative degradation reactions (O- and N-dealkylations) were found to be most promising in the release of VOCs. Thus, the CYP-catalyzed oxidative degradation reaction was encoded as SMIRKS (a programming language style to implement reactions based on the SMARTS description) to enumerate possible reaction products. (4) A quantitative structure property relation (QSPR) model aiming to predict the Henry constant H was derived from data for 488 organic compounds and identifies potentially VOCs amongst CYP reaction products. (5) A blacklist of naturally occurring breath components was implemented to identify marker molecules allowing straightforward detection within the exhaled air.peer-reviewe

Ultra high vacuum beam pipe of the Einstein Telescope project: Challenges and perspectives

The Einstein Telescope (ET) is a project aiming to realize a facility to host a gravitational wave (GW) detector of the third generation. The new instrument will change our vision of the Universe by observing millions of GW signals emitted during the coalescence of stellar and intermediate-mass black hole binary systems. It will permit to shed light on the first phase of the Universe formation and it will contribute to solving the dark matter enigma. The new GW detector is conceived as a series of six nested Michelson interferometers forming a triangle of 10 km side. The laser light biasing the interferometers must propagate in large ultra-high vacuum (UHV) tubes in order to reduce the noise induced by the residual gas pressure fluctuations, setting a requirement on the residual pressure in the 10 - 10 mbar range. The vacuum system will be made of a pipe with a 1 m diameter and an overall length of 120 km, making ET one of the largest UHV systems ever made. The giant UHV project asks for attentive optimization of material choice, manufacturing processes, post-processing treatments of the tubes, and pumping systems in order to find a cost-effective solution. In this article, we shortly review the vacuum solution adopted in the case of the second generation of GW detectors. After a general description of the main elements that constitute the ET vacuum system, the detailed design being the subject of the next 3 years of work, we will present a refined calculation of the noise due to residual-gas pressure fluctuations in the ET beam pipe

Synchrotron Radiation Research and Analysis of the Particulate Matter in Deep Ice Cores: An Overview of the Technical Challenges

Airborne dust extracted from deep ice core perforations can provide chemical and mineralogical insight into the history of the climate and atmospheric conditions, with unrivalled temporal resolution, time span and richness of information. The availability of material for research and the natural complexity of the particulate, however, pose significant challenges to analytical methods. We present the developments undertaken to optimize the experimental techniques, materials and protocols for synchrotron radiation-based analysis, in particular for the acquisition of combined Synchrotron Radiation X-Ray Fluorescence and X-ray Absorption Spectroscopy data

Synchrotron Radiation Research and Analysis of the Particulate Matter in Deep Ice Cores: An Overview of the Technical Challenges

Airborne dust extracted from deep ice core perforations can provide chemical and mineralogical insight into the history of the climate and atmospheric conditions, with unrivalled temporal resolution, time span and richness of information. The availability of material for research and the natural complexity of the particulate, however, pose significant challenges to analytical methods. We present the developments undertaken to optimize the experimental techniques, materials and protocols for synchrotron radiation-based analysis, in particular for the acquisition of combined Synchrotron Radiation X-Ray Fluorescence and X-ray Absorption Spectroscopy data

<i>fahd-1(tm5005) C</i>. <i>elegans</i> have a locomotion deficit.

<p>(A) 4-day old wild-type and <i>fahd-1(tm5005)</i> animals were placed on an empty NGM plate (without bacterial lawn) and the number of body bends was counted for one minute. <i>fahd-1(tm5005)</i> animals show fewer and more uncoordinated body bends compared to wild-type animals (28.53 ±SD 1.12 for wt vs. 11.57 ±SD 0.42 for <i>fahd-1(tm5005)</i>; p = 1.60E-05; N = 3 experiments (30 worms total)). (B) 4-day old wild type and <i>fahd-1(tm5005)</i> worms were put in the center of an NGM plate seeded with <i>E</i>. <i>coli</i> OP50. The radial dispersal rate (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134161#sec002" target="_blank">Materials and Methods</a>) was determined for three different time points (30 sec, 1 min, 2 min). The radial dispersal rate is decreased in <i>fahd-1(tm5005) C</i>. <i>elegans</i> compared to wild-type controls (3.41 ±SD 0.76 zones after two minutes for wt vs. 1.69 ±SD 0.11 zones after two minutes for <i>fahd-1(tm5005)</i>; p < 0.03 in all cases; N = 3 experiments (90 worms total)). (C) 4-day old wild-type and <i>fahd-1(tm5005)</i> hermaphrodites were screened for their swimming endurance performance in M9 buffer for up to 10 h. Wild-type worms are able to swim significantly longer than <i>fahd-1(tm5005)</i> worms (94.56% ±SD 4.72% swimming after 5 hours for wild-type vs. 23.72% ±SD 6.18 swimming after 10 hours for <i>fahd-1(tm5005)</i>; p = 0.001; N = 3 experiments (72 worms total)).</p

Expression and subcellular localization of FAHD-1 in nematodes.

<p>(A) Young adult and gravid adult hermaphrodites of the transcriptional reporter N2;<i>Ex</i>[p_{<i>fahd-1</i>}GFP, pRF4] were monitored by confocal microscopy. <i>fahd-1</i> seems to be expressed in most tissues, including pharynx, canal cell, neurons, vulva, intestine, and stomato-intestinal muscle. Representative pictures are shown. Size bar = 100 μm. (B) Confocal images of young adult <i>C</i>. <i>elegans</i> of the transcriptional reporter N2;<i>Ex</i>[p_{<i>fahd-1</i>}GFP, pRF4]. Representative images are shown. Size bar = 10 μm. <i>Upper left panel</i>: Detailed picture of <i>fahd-1</i> expression in the peri-vulvar region; vulva and uterine muscles are stained positive. <i>Upper right panel</i>: Detailed picture of <i>fahd-1</i> expression in the pharyngeal region; buccal cavity, procorpus, metacorpus, isthmus, posterior bulb, and pharyngeal-intestinal valve, as well as sensory neurons in the head were stained positive. <i>Lower left panel</i>: Detailed picture of <i>fahd-1</i> expression in the mid-body region; body wall muscles, lateral ganglion, dorsal chord (DC), and ventral nerve chord (VNC) were stained positive. <i>Lower right panel</i>: Detailed picture of <i>fahd-1</i> expression in the anus region; the stomato-intestinal muscles, the anus and the intestine were stained positive. (C) Temporal expression pattern of <i>fahd-1</i>. The translational reporter N2;<i>Ex</i>[p_{<i>fahd-1</i>}FAHD-1::GFP, pRF4] was examined (and pictured) by confocal fluorescence microscopy from the time point the eggs were laid at gastrula stage to 10-day old post fertile adults. GFP fluorescence was overlaid with phase-contrast microscopy. The FAHD1-1::GFP fusion protein is present in all stages from gastrulation to old worms. Representative images are shown. Size bar = 50 μm. (D) Young adult hermaphrodites of the translational reporter N2;<i>Ex</i>[p_{<i>fahd-1</i>}FAHD-1::GFP, pRF4] expressing the FAHD-1::GFP fusion protein (shown in green) were stained with 100 nM MitoTracker Red (shown in red) overnight. Shown here are confocal pictures of the pharynx region of the worm recorded in the green and red channel, as well as the merged pictures. Regions of overlapping staining (shown in yellow) are indicated by arrows. Representative pictures are shown. Size bar = 10 μm.</p