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The photoelectric conversion efficiency of perovskite solar cells has improved rapidly, but their stability is poor, which is an important factor that restricts their commercial production. This paper studies the physical and chemical stability of perovskite solar cells based on first principles. It is well known that methylamido lead iodide compounds and methylamino lead iodide compounds are easily degraded into NH2CHNH2I, CH3NH3I and PbI2. First, the chemical stability of the above two perovskite-type solar cell materials is discussed by calculating the binding energy. Then, their phonon scattering lines, state density and thermodynamic properties are calculated and analyzed, and the work functions of different types of crystals along different planes such as [1 0 0], [0 1 0 0], [0 0 1] and [1 1 1] are calculated. The results show that the work function of the methylamine iodized lead compound is greater than that of the methylamidine iodized lead compound, which means that the electrons of the methylamidine iodized lead compound escape more easily and the carrier transfer efficiency is higher under the same conditions. Finally, the effects of different temperatures, different electric fields and light on the two kinds of crystal materials are analyzed. This provides theoretical guidance for us to improve the stability of perovskite materials experimentally.

Introduction Patients with type 2 diabetes (T2D) receiving premixed insulin often fail to achieve optimal glycemic control. The insulin injection technique (IT) itself may be one of the factors affecting glycemic variability (GV). The aim of this study was to assess the relationship between GV and IT in patients with T2D using premixed insulin. Methods This was a single center, cross-sectional, and self-controlled trial. Patients with T2D using premixed insulin were enrolled as inpatients. The 4-day study consisted of a 2-day patient insulin injection period (days 0 and 1) and a 2-day specialist nurse insulin injection period (days 2 and 3). Patient insulin IT were assessed on day 1 by two independent nurses using a skill-related scale consisting of 15 items, with a maximum score for each item of 2 and a total optimum score of 30. All patients underwent 96-h continuous glucose monitoring (CGM) during the 4-day study, and CGM data collected on days 1 and 3 were recorded and analyzed. The primary outcome was the relationship between the insulin IT score and the 24-h mean amplitude glycemic excursion (MAGE) during the patient injection period. Results A total of 52 inpatients with T2D who used premixed insulin were recruited and completed the study. The mean total insulin IT score of these patients was considerably lower than the optimum score (17.0 ± 4.4 vs. 30). Our CGM data showed that the MAGE was significantly higher during the patient injection period than during the nurse injection period (P

Plasma is an efficient method that can activate inert molecules such as methane and carbon dioxide in a mild environment to make them reactive. In this work, we have prepared an AE-NiO/γ-Al2O3 catalyst using an ammonia-evaporation method for plasma promoted dry reforming reaction of CO2 and CH4 at room temperature. According to the characterization data of XRD, H2-TPR, TEM, XPS, etc., the AE-NiO/γ-Al2O3 catalyst has higher dispersion, smaller particle size and stronger metal-support interaction than the catalyst prepared by the traditional impregnation method. In addition, the AE-NiO/γ-Al2O3 catalyst also exhibits higher activity in dry reforming reaction. This work provides a feasible reference experience for the research of plasma promoted dry reforming reaction catalysts at room temperature.

The interparticle friction behavior of saturated clay controls its mechanical properties, but remains unclear at nanoscale. As one of major clay minerals, the hydrated montmorillonite (MMT) is selected to investigate the nanoscale friction characteristics using Molecular Dynamics simulation method. Two portions of MMT representing two particles with a water film in the middle are created to simulate an undrained system. A virtual spring is applied on the upper MMT portion to provide the sliding with a constant velocity relative to the bottom portion. The effects of normal load and sliding velocity on the frictional behavior are then investigated. The friction coefficients of hydrated MMT at different cases were measured and compared with other experimental and simulation results for the validation. The evolution of normal load with the number of hydrogen bonds for hydrated MMT was finally analyzed. All simulation results indicated that the friction load fluctuated periodically with a cycle of about 9.10 A at sliding velocity inferior 0.001 A•fs−1, which was nearly equal to montmorillonite's lattice constant along the sliding direction; the fluctuation amplitude of the friction load increased with the decreasing sliding velocity; the relationship between the average friction load and the logarithm of sliding velocity followed a power function; the friction coefficient and the cohesion were found to increase approximately linearly with sliding velocity.

Carbon dioxide, a greenhouse gas mainly from the consumption of fossil fuel, is regarded as an attractive feedstock in view of synthetic chemistry. Great efforts have been devoted to developing catalytic processes for converting CO2 into value-added compounds with reduced carbon footprint. Among versatile applications in organic synthesis, CO2 can serve as a promising raw material for fuel production, especially methanol. ‘Coming from fuel and returning to fuel’ is an appealing objective in terms of sustainable development associated with circumventing the energy shortage and CO2 issue. To date, metal complexes and organocatalysts for CO2 hydrogenation to methanol have been developed along with the reaction mechanistic insight. Understanding the interaction of active catalytic species with CO2 or hydrogen could account for development of efficient homogeneous catalysts. In this context, homogeneous catalytic hydrogenation of CO2 and its derivatives into methanol is highlighted in this article in combination with mechanistic understanding on a molecular level.

Carbon dioxide utilization has continued to capture the interest of chemists worldwide due to global warming associated with positive carbon accumulation. As an environmentally friendly C1 feedstock, the reaction of carbon dioxide has been extensively investigated for several decades. On the other hand, acrylic acid is a valuable industrial product that is widely used for various important purposes in industry. From the point view of atom- and process-economical chemistry, the most concise and promising route for acrylic acid derivatives synthesis would be direct carboxylation of olefins or alkynes with carbon dioxide. In this review, we would like to discuss and update the latest advances on synthesis of acrylic acid derivatives from unsaturated hydrocarbons and carbon dioxide.

The selective aerobic oxidation of alkynes to corresponding α,β-acetylenic ketones was achieved in polyethylene glycol/dense CO 2 /O 2 biphasic system without any catalyst or additive. The effects of reaction parameters, e.g. temperature, CO 2 pressure, PEG molecular weight and loading on the reaction were carefully examined. Moreover, various substrates worked well in the presence of PEG1000 under 5 MPa of CO 2 and 2 MPa of O 2 at 100 °C for 12 to 24 h and acceptable yield and selectivity could be obtained in most cases. Preliminary mechanistic investigations were also discussed.

It is not easy to distinguish hybrid pines using their morphological characteristics. Traditional methods of identification, such as chemical analysis or molecular marker technology, are complicated, time-consuming and costly and are not very accurate. They are not, therefore, an ideal means of identification and the use of near-infrared technology, which is comparatively inexpensive and simple to use, is preferable. For the future development of Pinus taedax P. caribaea var. hondurensis (PTC) hybrid trials and breeding programmes, and to provide a more comprehensive understanding of their physiological and biochemical characteristics, it is necessary to identify PTC among the parents ( P. elliottii, P. taeda and P. caribaea var. hondurensis) and other possible hybrids ( P. elliottiix P. caribaea var. hondurensis) in order to be able to distinguish them from each other. In this study, partial least-squares discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) regression modelling are used, The results are as follows: PLS-DA has a low accuracy rate, at 89.09%, but using the PLS-DA scores as the input data into the LDA resulted in LDA distinction models, with accuracy rates reaching 99%, allowing a reliable identification of pure species and hybrids. It is clear from the results that near infrared technology can be used to identify hybrid and purebreds in pine and that the accuracy rate is higher than that derived when using standard molecular techniques.

An efficient CuI-catalyzed carboxylation of terminal alkynes under mild conditions and without the need of any additional ligand is developed.

Carbon capture and storage/sequestration (CCS) is now being considered as a potential option to mitigate global warming associated with carbon accumulation. The chemical absorption technique employing efficient amino-containing absorbents has been widely developed. Nevertheless, extensive energy consumption in desorption–compression process would be a crucial barrier to realize practical CCS. On the other hand, CO2 is very attractive as a typical renewable feedstock for manufacturing commodity chemicals and fuels. However, the reactions involving CO2 are commonly carried out at high pressure, which may not be economically suitable and also pose safety concerns. Consequently, we have proposed a carbon capture and utilization (CCU) strategy as an alternative approach to addressing energy issue in CCS. This crucial point of CCU could be simultaneous activation of CO2 upon its capture (e.g., formation of carbamate/alkyl carbonate) and thus in situ catalytic transformation into value-added chemicals under mild conditions, avoiding additional desorption step. This chapter is intended to discuss carbon capture and in situ transformation of CO2 to oxazolidinones, carbonates, quinazolines, urea derivatives, isocyanates, and carbamates via the formation of C O and C N bond.

The oxidation of sulfides (I) with Oxone in ethanol leads to sulfoxides (II), while the oxidation in water affords sulfones (III) in high yields.

An efficient heterogeneous silver-catalyzed reaction for construction of the α-methylene cyclic carbonate motif was developed through carboxylative assembly of propargyl alcohols and CO2. Such a CO2 fixation protocol proceeded smoothly with only 1 mol% of Ag2WO4 and 2 mol% of PPh3 as well as atmospheric CO2 at room temperature under solvent-free conditions, in an environmentally benign and low energy manner along with an easy operating procedure. Notably, up to 98% isolated yields of carbonates could be attained with exclusive chemo-selectivity. In addition, the dual activation capacity of Ag2WO4 towards both the propargylic substrate and CO2 is based on which cooperative catalytic mechanism by the silver cation and the tungstate anion is proposed. Recycling trials on carboxylative cyclization of propargyl alcohols and CO2 illustrate that the catalyst can be reused at least 4 times with retention of high catalytic activity and selectivity. Especially, it allows the direct and effective application in the one-pot synthesis of various oxazolidinones bearing exocyclic alkenes and carbamates in moderate to high yields upon the alternative introduction of primary or secondary amines.

The CuI-catalyzed carboxylation of terminal alkynes with CO2 and alkyl halides using ethylene carbonate as the solvent under mild conditions was studied. DFT calculations reveal that the energy barrier for CO2 insertion into the sp-hybridized Cu-C bond could be reduced by employing ethylene carbonate as the solvent. Notably, the procedure was conducted under ambient CO2 pressure without any external ligands. A broad range of substrates with electron-withdrawing groups or electron-donating groups gave the corresponding products in reasonable yields.

PEG400 is employed as an efficient phase transfer catalyst for the cycloaddition reaction of imines with dichlorocarbene, which is generated in situ from chloroform and sodium hydroxide, to give gem-dichloroaziridines in moderate to excellent yields at ambient temperature. This protocol is also extended to the synthesis of cyclopropanes from a variety of alkenes. In this study, PEG400 behaves as a phase transfer reagent thanks to its ability to coordinate with alkali metal cations. Notably, the one-pot synthesis of gem-dichloroaziridines from benzaldehyde and aromatic amines has also been successfully performed. The in situ generated acid, derived from CO2 and H2O, can also be effectively applied to promote the amide synthesis via the gem-dichloroaziridine pathway. The application of the gem-dichlorocyclopropane as a platform chemical is also briefly demonstrated, to afford the 2-phenylacrylaldehyde derivative via a ring-opening reaction.

Selective oxidation of sulfides was successfully performed by employing oxone (2KHSO5·KHSO4·K2SO4) as oxidant without utilization of any catalyst/additive under mild reaction conditions. Notably, the reaction can be controlled by the chosen solvent. When ethanol was used as the solvent, sulfoxides were obtained in excellent yield; the reaction almost exclusively gave the sulfone in water. Furthermore, this protocol worked well for various sulfides to the corresponding sulfoxides in ethanol or sulfones in water.

The tape-scraper tribosystem of ATM (Auto Teller Machine) was used to study the wear properties of polymer tapes of PEN (polyethylene-2, 6-naphthalenedicarboxylate) and PI (polyimide) sliding against polymer scraper of POM (polyoxymethylene) in the clean air environment and in the simulated environment of sand dust with the natural sand from the desert. As main results, the mean wear rate of the PEN tape in the sand storm environment was about 500 times of that in the clean environment and the mean wear rate of the PI tape in the sand storm environment was about 1700 times of that in the clean environment. The PI tape exhibited higher abrasive resistance than the PEN tape. The bill substrate increased the abrasive resistance of polymer tapes. The micro wear mechanism examination showed the plastic flow and the broken of fibers for PEN tape and block fracture due to brittle nature for PI tape.Copyright © 2005 by ASME