Model of LPG Refrigerator: A Literature Review

This work investigates the result of an experimental study carried out to determine the Coefficient of performance of domestic refrigerator when a propane-butane mixture is liquefied petroleum gas (LPG) which is available and comprises 56.4% butane, 24.4%propane, and 17.2% isobutene. This paper also presented an experimental investigation of COP by the effect of changing capillary tube length, capillary tube inner diameter and capillary coil diameter on the mass flow rate of refrigerant in an adiabatic helical capillary tube. Large amount of electricity supply is not available easily in large part of underdevelopment country like India. It will also prove to be an effective for remote area such as research sites, mines, & deserts where electricity is generally not available. The LPG is cheaper and possesses an environmental free in nature with no ozone depletion potential (ODP). Also LPG is available as a side product in local refineries. The results of the present work indicate the successful use of this propane-butane mixture as an alternative refrigerant to CFCs and HFCs in domestic refrigerator. It would include Experimental setup of working model and detailed observation of the LPG refrigerator and represents its application in refinery, hotel, chemical industries where requirement of LPG is more. Keywords: LPG refrigerator, domestic refrigerator, eco friendly refrigerants, Mixed Refrigerant

One-Year Water-Stable and Porous Bi(III) Halide Semiconductor with Broad-Spectrum Antibacterial Performance

Hybrid metal halide semiconductors are a unique family of materials with immense potential for numerous applications. For this to materialize, environmental stability and toxicity deficiencies must be simultaneously addressed. We report here a porous, visible light semiconductor, namely, (DHS)Bi2I8 (DHS = [2.2.2] cryptand), which consists of nontoxic, earth-abundant elements, and is water-stable for more than a year. Gas- and vapor-sorption studies revealed that it can selectively and reversibly adsorb H2O and D2O at room temperature (RT) while remaining impervious to N2 and CO2. Solid-state NMR measurements and density functional theory (DFT) calculations verified the incorporation of H2O and D2O in the molecular cages, validating the porous nature. In addition to porosity, the material exhibits broad band-edge light emission centered at 600 nm with a full width at half-maximum (fwhm) of 99 nm, which is maintained after 6 months of immersion in H2O. Moreover, (DHS)Bi2I8 exhibits bacteriocidal action against three Gram-positive and three Gram-negative bacteria, including antibiotic-resistant strains. This performance, coupled with the recorded water stability and porous nature, renders it suitable for a plethora of applications, from solid-state batteries to water purification and disinfection

The United States COVID-19 Forecast Hub dataset

Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages

Etude des relations structure-stabilité-propriété dans les pérovskites hybrides par spectroscopie RMN à l'état solide

In the last decade, there has been a progressive increase in the performance of solution-processed hybrid lead halide perovskite solar cells (PSCs), which has been enabled by means of compositional tailoring and interfacial engineering of the perovskite absorber layer and the charge transport layers. However, the long-term operational stability of these materials, including state-of-the-art perovskite formulations, is a major bottleneck in commercializing these materials. In this context, the main objective of this thesis is to understand the different degradation reactions and kinetics aspects of these reactions in hybrid perovskite layers and charge transport layers, especially in the presence of moisture. The degradation reactions in methylammonium (MA) and formamidinium (FA)-based perovskite formulation, in particular, MAPbI3, FAPbI3, and CsMAFAPbIxBr3-x, which are among the high-performing perovskite formulations in PSCs, are studied, analyzed, and compared. In doing so, these materials in crystalline and thin film forms are exposed to low (40% relative humidity, RH) and high (85% RH) water-vapor concentrations. However, the coexistence of the different organic/inorganic and hybrid byproducts and dilute concentrations of different phases formed during the degradation reactions raise challenges in terms of structural characterization. A multi-technique approach involving XRD, microscopy, and solid-state (ss)NMR spectroscopy has been employed to characterize the different degradation products. As a quantitative local characterization technique, ssNMR spectroscopy has notably the ability to probe dilute concentrations of organic byproducts formed upon degradation, which are challenging to detect using other structure-determining techniques. In particular, insights into the moisture-induced phase transformation reactions of FAPbI3 as a function of water vapor concentration, particle size, and light illumination have been obtained by this multi-technique approach. This concept has been later extended to investigate the cascading degradation reactions in MAPbI3-based perovskites with and without surface passivating agents. Our studies indicate that the stability of the perovskite can be adjusted from a few days to several months, depending on the moisture-exposure conditions. Finally, a combination of ssNMR, ssEPR, and computational modelling (NMR crystallography) has been employed to gain insight into the structure-stability-property relationship in a hole-transporting layer spiro-OMeTAD. A detailed study of degradation reactions using multiscale characterization techniques described in this thesis has wider implications for the molecular-level understanding of structure-processing-stability-property relationships in hybrid perovskites and charge transport layers.Les performances des cellules solaires à base de pérovskites hybrides contenant des halogénures de plomb (PSC) ont été fortement améliorées depuis dix ans. Ces améliorations ont été rendues possibles en ajustant les compositions et en jouant sur la nature des interfaces des couches de pérovskite et de transport de charge. Cependant, la stabilité opérationnelle à long terme de ces matériaux reste un problème majeur dans l'optique d'une commercialisation de ces matériaux. Dans ce contexte, l'objectif principal de cette thèse est de comprendre les différentes réactions de dégradation et les aspects cinétiques de ces réactions dans les couches de pérovskites hybrides et les couches de transport de charge, notamment en atmosphère humide. Nous avons notamment analysé les réactions de dégradation des pérovskites à base de méthylammonium (MA) et de formamidinium (FA), en particulier MAPbI3, FAPbI3 et CsMAFAPbIxBr3x. Ces matériaux sous forme de cristaux et de couches minces ont été exposés à des concentrations faibles (40%) et élevées (85%) de vapeur d'eau. Cependant, la coexistence des différents sous-produits organiques/inorganiques et hybrides ainsi que les concentrations diluées des différentes phases formées lors des réactions de dégradation posent des difficultés en terme de caractérisation structurale. Une approche multi-technique combinant la diffraction des rayons, la microscopie et la spectroscopie RMN à l'état solide a été utilisée pour caractériser les différents produits de dégradation. En particulier, la spectroscopie RMN des solides, en tant que méthode de caractérisation locale quantitative, permet de mesurer des concentrations diluées de sous-produits organiques formés lors de la dégradation, qui sont difficiles à détecter à l'aide d'autres techniques de caractérisation. En particulier, cette approche multi-technique a permis d'obtenir des informations uniques sur les transformations de phase du FAPbI3 en fonction du taux d'humidité, de la taille des particules et de l'irradiation lumineuse. Cette approche a ensuite été étendue pour étudier les réactions de dégradation en cascade des pérovskites à base de MAPbI3 avec et sans agent passivant de surface. Enfin, des mesures RMN et RPE sur les solides ont été combinées avec des calculs de chimie théorique, selon une approche de cristallographie RMN, afin de mieux comprendre la relation structure-stabilité-propriété dans un matériau de transport de trous, spiro-OMeTAD. Une étude détaillée des réactions de dégradation à l'aide de techniques de caractérisation multi-échelles décrites dans cette étude a des implications plus larges pour la compréhension au niveau moléculaire des relations structure-traitement-stabilité-propriété dans les pérovskites hybrides et les semi-conducteurs organiques

Etude des relations structure-stabilité-propriété dans les pérovskites hybrides par spectroscopie RMN à l'état solide

Les performances des cellules solaires à base de pérovskites hybrides contenant des halogénures de plomb (PSC) ont été fortement améliorées depuis dix ans. Ces améliorations ont été rendues possibles en ajustant les compositions et en jouant sur la nature des interfaces des couches de pérovskite et de transport de charge. Cependant, la stabilité opérationnelle à long terme de ces matériaux reste un problème majeur dans l'optique d'une commercialisation de ces matériaux. Dans ce contexte, l'objectif principal de cette thèse est de comprendre les différentes réactions de dégradation et les aspects cinétiques de ces réactions dans les couches de pérovskites hybrides et les couches de transport de charge, notamment en atmosphère humide. Nous avons notamment analysé les réactions de dégradation des pérovskites à base de méthylammonium (MA) et de formamidinium (FA), en particulier MAPbI3, FAPbI3 et CsMAFAPbIxBr3x. Ces matériaux sous forme de cristaux et de couches minces ont été exposés à des concentrations faibles (40%) et élevées (85%) de vapeur d'eau. Cependant, la coexistence des différents sous-produits organiques/inorganiques et hybrides ainsi que les concentrations diluées des différentes phases formées lors des réactions de dégradation posent des difficultés en terme de caractérisation structurale. Une approche multi-technique combinant la diffraction des rayons, la microscopie et la spectroscopie RMN à l'état solide a été utilisée pour caractériser les différents produits de dégradation. En particulier, la spectroscopie RMN des solides, en tant que méthode de caractérisation locale quantitative, permet de mesurer des concentrations diluées de sous-produits organiques formés lors de la dégradation, qui sont difficiles à détecter à l'aide d'autres techniques de caractérisation. En particulier, cette approche multi-technique a permis d'obtenir des informations uniques sur les transformations de phase du FAPbI3 en fonction du taux d'humidité, de la taille des particules et de l'irradiation lumineuse. Cette approche a ensuite été étendue pour étudier les réactions de dégradation en cascade des pérovskites à base de MAPbI3 avec et sans agent passivant de surface. Enfin, des mesures RMN et RPE sur les solides ont été combinées avec des calculs de chimie théorique, selon une approche de cristallographie RMN, afin de mieux comprendre la relation structure-stabilité-propriété dans un matériau de transport de trous, spiro-OMeTAD. Une étude détaillée des réactions de dégradation à l'aide de techniques de caractérisation multi-échelles décrites dans cette étude a des implications plus larges pour la compréhension au niveau moléculaire des relations structure-traitement-stabilité-propriété dans les pérovskites hybrides et les semi-conducteurs organiques.In the last decade, there has been a progressive increase in the performance of solution-processed hybrid lead halide perovskite solar cells (PSCs), which has been enabled by means of compositional tailoring and interfacial engineering of the perovskite absorber layer and the charge transport layers. However, the long-term operational stability of these materials, including state-of-the-art perovskite formulations, is a major bottleneck in commercializing these materials. In this context, the main objective of this thesis is to understand the different degradation reactions and kinetics aspects of these reactions in hybrid perovskite layers and charge transport layers, especially in the presence of moisture. The degradation reactions in methylammonium (MA) and formamidinium (FA)-based perovskite formulation, in particular, MAPbI3, FAPbI3, and CsMAFAPbIxBr3-x, which are among the high-performing perovskite formulations in PSCs, are studied, analyzed, and compared. In doing so, these materials in crystalline and thin film forms are exposed to low (40% relative humidity, RH) and high (85% RH) water-vapor concentrations. However, the coexistence of the different organic/inorganic and hybrid byproducts and dilute concentrations of different phases formed during the degradation reactions raise challenges in terms of structural characterization. A multi-technique approach involving XRD, microscopy, and solid-state (ss)NMR spectroscopy has been employed to characterize the different degradation products. As a quantitative local characterization technique, ssNMR spectroscopy has notably the ability to probe dilute concentrations of organic byproducts formed upon degradation, which are challenging to detect using other structure-determining techniques. In particular, insights into the moisture-induced phase transformation reactions of FAPbI3 as a function of water vapor concentration, particle size, and light illumination have been obtained by this multi-technique approach. This concept has been later extended to investigate the cascading degradation reactions in MAPbI3-based perovskites with and without surface passivating agents. Our studies indicate that the stability of the perovskite can be adjusted from a few days to several months, depending on the moisture-exposure conditions. Finally, a combination of ssNMR, ssEPR, and computational modelling (NMR crystallography) has been employed to gain insight into the structure-stability-property relationship in a hole-transporting layer spiro-OMeTAD. A detailed study of degradation reactions using multiscale characterization techniques described in this thesis has wider implications for the molecular-level understanding of structure-processing-stability-property relationships in hybrid perovskites and charge transport layers

Etude des relations structure-stabilité-propriété dans les pérovskites hybrides par spectroscopie RMN à l'état solide

In the last decade, there has been a progressive increase in the performance of solution-processed hybrid lead halide perovskite solar cells (PSCs), which has been enabled by means of compositional tailoring and interfacial engineering of the perovskite absorber layer and the charge transport layers. However, the long-term operational stability of these materials, including state-of-the-art perovskite formulations, is a major bottleneck in commercializing these materials. In this context, the main objective of this thesis is to understand the different degradation reactions and kinetics aspects of these reactions in hybrid perovskite layers and charge transport layers, especially in the presence of moisture. The degradation reactions in methylammonium (MA) and formamidinium (FA)-based perovskite formulation, in particular, MAPbI3, FAPbI3, and CsMAFAPbIxBr3-x, which are among the high-performing perovskite formulations in PSCs, are studied, analyzed, and compared. In doing so, these materials in crystalline and thin film forms are exposed to low (40% relative humidity, RH) and high (85% RH) water-vapor concentrations. However, the coexistence of the different organic/inorganic and hybrid byproducts and dilute concentrations of different phases formed during the degradation reactions raise challenges in terms of structural characterization. A multi-technique approach involving XRD, microscopy, and solid-state (ss)NMR spectroscopy has been employed to characterize the different degradation products. As a quantitative local characterization technique, ssNMR spectroscopy has notably the ability to probe dilute concentrations of organic byproducts formed upon degradation, which are challenging to detect using other structure-determining techniques. In particular, insights into the moisture-induced phase transformation reactions of FAPbI3 as a function of water vapor concentration, particle size, and light illumination have been obtained by this multi-technique approach. This concept has been later extended to investigate the cascading degradation reactions in MAPbI3-based perovskites with and without surface passivating agents. Our studies indicate that the stability of the perovskite can be adjusted from a few days to several months, depending on the moisture-exposure conditions. Finally, a combination of ssNMR, ssEPR, and computational modelling (NMR crystallography) has been employed to gain insight into the structure-stability-property relationship in a hole-transporting layer spiro-OMeTAD. A detailed study of degradation reactions using multiscale characterization techniques described in this thesis has wider implications for the molecular-level understanding of structure-processing-stability-property relationships in hybrid perovskites and charge transport layers.Les performances des cellules solaires à base de pérovskites hybrides contenant des halogénures de plomb (PSC) ont été fortement améliorées depuis dix ans. Ces améliorations ont été rendues possibles en ajustant les compositions et en jouant sur la nature des interfaces des couches de pérovskite et de transport de charge. Cependant, la stabilité opérationnelle à long terme de ces matériaux reste un problème majeur dans l'optique d'une commercialisation de ces matériaux. Dans ce contexte, l'objectif principal de cette thèse est de comprendre les différentes réactions de dégradation et les aspects cinétiques de ces réactions dans les couches de pérovskites hybrides et les couches de transport de charge, notamment en atmosphère humide. Nous avons notamment analysé les réactions de dégradation des pérovskites à base de méthylammonium (MA) et de formamidinium (FA), en particulier MAPbI3, FAPbI3 et CsMAFAPbIxBr3x. Ces matériaux sous forme de cristaux et de couches minces ont été exposés à des concentrations faibles (40%) et élevées (85%) de vapeur d'eau. Cependant, la coexistence des différents sous-produits organiques/inorganiques et hybrides ainsi que les concentrations diluées des différentes phases formées lors des réactions de dégradation posent des difficultés en terme de caractérisation structurale. Une approche multi-technique combinant la diffraction des rayons, la microscopie et la spectroscopie RMN à l'état solide a été utilisée pour caractériser les différents produits de dégradation. En particulier, la spectroscopie RMN des solides, en tant que méthode de caractérisation locale quantitative, permet de mesurer des concentrations diluées de sous-produits organiques formés lors de la dégradation, qui sont difficiles à détecter à l'aide d'autres techniques de caractérisation. En particulier, cette approche multi-technique a permis d'obtenir des informations uniques sur les transformations de phase du FAPbI3 en fonction du taux d'humidité, de la taille des particules et de l'irradiation lumineuse. Cette approche a ensuite été étendue pour étudier les réactions de dégradation en cascade des pérovskites à base de MAPbI3 avec et sans agent passivant de surface. Enfin, des mesures RMN et RPE sur les solides ont été combinées avec des calculs de chimie théorique, selon une approche de cristallographie RMN, afin de mieux comprendre la relation structure-stabilité-propriété dans un matériau de transport de trous, spiro-OMeTAD. Une étude détaillée des réactions de dégradation à l'aide de techniques de caractérisation multi-échelles décrites dans cette étude a des implications plus larges pour la compréhension au niveau moléculaire des relations structure-traitement-stabilité-propriété dans les pérovskites hybrides et les semi-conducteurs organiques

Global mistranslation increases cell survival under stress in Escherichia coli.

Mistranslation is typically deleterious for cells, although specific mistranslated proteins can confer a short-term benefit in a particular environment. However, given its large overall cost, the prevalence of high global mistranslation rates remains puzzling. Altering basal mistranslation levels of Escherichia coli in several ways, we show that generalized mistranslation enhances early survival under DNA damage, by rapidly activating the SOS response. Mistranslating cells maintain larger populations after exposure to DNA damage, and thus have a higher probability of sampling critical beneficial mutations. Both basal and artificially increased mistranslation increase the number of cells that are phenotypically tolerant and genetically resistant under DNA damage; they also enhance survival at high temperature. In contrast, decreasing the normal basal mistranslation rate reduces cell survival. This wide-ranging stress resistance relies on Lon protease, which is revealed as a key effector that induces the SOS response in addition to alleviating proteotoxic stress. The new links between error-prone protein synthesis, DNA damage, and generalised stress resistance indicate surprising coordination between intracellular stress responses and suggest a novel hypothesis to explain high global mistranslation rates

Cooperative Self-Assembly Driven by Multiple Noncovalent Interactions: Investigating Molecular Origin and Reassessing Characterization.

International audienceCooperative interactions play a pivotal role in programmable supramolecular assembly. Emerging from a complex interplay of multiple noncovalent interactions, achieving cooperativity has largely relied on empirical knowledge. Its development as a rational design tool in molecular self-assembly requires a detailed characterization of the underlying interactions, which has hitherto been a challenge for assemblies that lack long-range order. We employ extensive one- and two-dimensional magic-angle-spinning (MAS) solid-state NMR spectroscopy to elucidate key structure-directing interactions in cooperatively bound aggregates of a perylene bisimide (PBI) chromophore. Analysis of 1H-13C cross-polarization heteronuclear correlation (CP-HETCOR) and 1H-1H double-quantum single-quantum (DQ-SQ) correlation spectra allow the identification of through-space 1H···13C and 1H···1H proximities in the assembled state and reveals the nature of molecular organization in the solid aggregates. Emergence of cooperativity from the synergistic interaction between a stronger π-stacking and a weaker interstack hydrogen-bonding is elucidated. Finally, using a combination of optical absorption, circular dichroism, and high-resolution MAS NMR spectroscopy based titration experiments, we investigate the anomalous solvent-induced disassembly of aggregates. Our results highlight the disparity between two well-established approaches of characterizing cooperativity, using thermal and good solvent-induced disassembly. The anomaly is explained by elucidating the difference between two disassembly pathways

Chemical exchange of labile protons by deuterium enables selective detection of pharmaceuticals in solid formulations

International audienceChemically assisted swapping of labile protons by deuterons is presented for amino acids, polysaccharides, pharmaceutical compounds, and their solid formulations. Solid-state packing interactions in these compounds are elucidated by 1H–2H isotope correlation NMR spectroscopy (iCOSY). A minuscule concentration of dopamine, 5 wt% or ∼100 μg, in a solid formulation can be detected by 2H NMR at 28.2 T (1H, 1200 MHz) in under a minute

Amelioration of lignocellulose valorization by measuring and understanding nanoscale compositions and structures through solid-state NMR spectroscopy

International audienc