Stabilizing perovskite precursors with the reductive natural amino acid for printable mesoscopic perovskite solar cells

Solution processability significantly advances the development of highly-efficient perovskite solar cells.However,the precursor solution tends to undergo irreversible degradation reactions,impairing the device performance and reproducibility.Here,we utilize a reductive natural amino acid,Nacetylcysteine(NALC),to stabilize the precursor solution for printable carbon-based hole-conductorfree mesoscopic perovskite solar cells.We find that I_(2) can be generated in the aged solution containing methylammonium iodide(MI) in an inert atmosphere and speed up the MA-FA^(+)(formamidinium) reaction which produces large-size cations and hinders the formation of perovskite phase.NALC effectively stabilizes the precursor via its sulfhydryl group which reduces I_(2) back to I^(-)and provides H^(+).The NALC-stabilized precursor which is aged for 1440 h leads to devices with a power conversion efficiency equivalent to 98% of that for devices prepared with the fresh precursor.Furthermore,NALC improves the device power conversion efficiency from 16.16% to 18.41% along with enhanced stability under atmospheric conditions by modifying grain boundaries in perovskite films and reducing associated defects.

Efficient light-driven reductive amination of furfural to furfurylamine over ruthenium-cluster catalyst

Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reactions.Herein,the ultrasmall Ru nanoclusters(~0.9 nm)were successfully fabricated over P25 support with positive charged Ru^(δ+)species at the interface.A new route was developed to achieve the furfural(FAL)to furfurylamine(FAM)by coupling the light-driven reductive amination and hydrogen transfer of ethanol over this type catalyst.Strikingly,the photocatalytic activity and selectivity are strongly dependent on the particle size and electronic structure of Ruthenium.The Ru^(δ+)species at the interface promote the formation of active imine intermediates;moreover,the Ru nanoclusters facilitate the separation efficiency of electrons and holes as well as accelerate the further hydrogenation of imine intermediates to product primary amines.In contrast Ru particles in larger nanometer size facilitate the formation of the furfuryl alcohol and excessive hydrogenation products.In addition,the coupling byproducts can be effectively inhibited via the construction of sub-nanocluster.This study offers a new path to produce the primary amines from biomass-derived carbonyl compounds over hybrid semiconductor/metal-clusters photocatalyst via light-driven tandem catalytic process.

Developing a GIS Audit Framework in the Context of Information Technology though a Reductive Model Approach

A GIS audit framework is necessary considering the diverse nature of GIS with regard to components, applications and industry. In practice, checklists are generated during the audit process based on specific objectives. There is no standardized list of items that can be used as a reference. The purpose of this study was to develop a GIS audit framework as a foundation for GIS audits. The framework provides that comprehensive approach to various GIS aspects during the audit process. The design builds on a developed conceptual framework where most significant categories of GIS audit parameters namely data quality, software utilization, GIS competency and procedures (work flows) were identified. The study adopted a reductive model approach to simplify the complexity associated with each category of GIS audit parameter. The resultant audit elements for each category are organized in a matrix that forms an integral part of the framework. The columns comprise audit goal, audit questions and audit subjects as indicators which are qualitatively measured. The rows comprise the parameters (data quality, software utilization, personnel competency and procedure (workflows)). To use the framework, an auditor only needs to create an audit checklist that consists of particular parameters and indicators from the framework depending on audit objective. As part of an on-going research, the next step will involve validating the framework through a mock testing process.

Selectively reductive amination of levulinic acid with aryl amines to N-substituted aryl pyrroles

Synthesizing nitrogen(N)-containing molecules from biomass derivatives is a new strategy for production of this kind of chemicals.Herein,for the first time we present the synthesis of N-substituted aryl pyrroles via reductive amination/cyclization of levulinic acid(LA)with primary aromatic amines and hydrosilanes(e.g.,PMHS)over Cs F,and a series of N-substituted aryl pyrroles could be obtained in good to excellent yields at 120○C.The mechanism investigation indicates that the reaction proceeds in two steps:the cyclization between amine and LA occurs first to form intermediate 5-methyl-N-alkyl-1,3-dihydro-2H-pyrrolones and their isomeride(B),and then the chemo-and region-selective reduction of intermediates take place to produce the final products.This approach for synthesis of N-substituted aryl pyrroles can be performed under mild and green conditions,which may have promising applications.

NATURALLY REDUCTIVE(α_(1),α_(2))METRICS

Letting F be a homogeneous(α_(1),α_(2))metric on the reductive homogeneous manifold G/H,we first characterize the natural reductiveness of F as a local f-product between naturally reductive Riemannian metrics.Second,we prove the equivalence among several properties of F for its mean Berwald curvature and S-curvature.Finally,we find an explicit flag curvature formula for G/H when F is naturally reductive.

Improvement of AlN Thermal Conductivity Based on Reductive Compound Additives

AlN ceramics were prepared by plasma activation sintering(PAS)with compound additives yttrium acetylacetonate(Y(acac)_(3))and melamine(C_(3)H_(6)N_(6)).The effects of compound additives on the microstructure,density,and thermal properties of Al N ceramic were studied.Y(acac)3and C_(3)H_(6)N_(6)can form Y_(2)O_(3),residual organic carbon and reducing gas during the heating process,which improves the Al N sintering performance at a temperature of 1700℃and the bulk thermal conductivity.When the content of Y(acac)_(3)is 10 wt%and C_(3)H_(6)N_(6)is 3 wt%,the thermal conductivity of Al N ceramics is 105.6 W/(m·K),which is much higher than that of Al N ceramics with Y_(2)O_(3)under the same sintering conditions.This work provides theoretical reference for the preparation of high-performance Al N ceramic.

Mechano-chemical sulfidization of zinc oxide by grinding with sulfur and reductive additives

A novel process for sulfidation of ZnO by co-grinding with sulfur and reductive additives （P, Fe, A1, and Mg） was developed. The sulfidation extent of ZnO with the addition of P, Fe, A1 or Mg can reach 85.2%, 81.6%, 96.7% and 92.6% after grinding for 4, 6, 1 and 1 h, respectively. Based on the chemical phase composition analysis and morphological characteristics of sulfidized products by XRD, SEM and TEM, a possible reaction mechanism, mechanically induced self-propagating reaction （MSR）, was proposed to explain the sulfidization reaction. In addition, the floatability of sulfidized products was investigated for the recovery of metal sulfide and ZnS can be concentrated with a high concentration ratio and concentrate grade. By using the sulfidizing process, it is expected that the recovery of zinc from the wastes or purification of heavy-metal-containing hazardous residues is technically feasible.

Reductive leaching of zinc and indium from industrial zinc ferrite particulates in sulphuric acid media

Zinc ferrite is the principal constituent in zinc neutral-leach residue（NLR） which is commonly treated by hot-acid leaching in electrolytic zinc plants. Reductive leaching of zinc ferrite with sphalerite concentrate as a reducing agent was performed. It was found that leaching of zinc ferrite in the presence of sphalerit concentrate was a viable process that effectively extracted zinc and indium and converted Fe^3＋ into Fe^2＋ at the same time. Reflux leaching tests by two stages were performed to achieve extractions of 98.1% for zinc and 97.5% for indium, and a Fe^2＋/Fe^3＋ molar ratio of 9.6 in leach solution was also obtained. The leaching behaviors of other elements, such as iron, copper and tin were also studied. The results showed that iron and copper were completely leached, whereas tin presented lower extraction values.

Reaction behavior of ferric oxide in system Fe_2O_3-SiO_2-Al_2O_3 during reductive sintering process

Pure compounds and kaolin were employed to investigate the reaction behavior of ferric oxide in thetrinarysystem Fe2O3?SiO2?Al2O3 during reductive sintering process. The thermodynamic analyses and reductive sintering experimental results show that ferrous oxide generated from the reduction of ferric oxide by carbon can react with silicon dioxide and aluminum oxide to form ferrous silicate and hercynite at 1173 K, respectively. In the trinary system Fe2O3?SiO2?Al2O3, ferrous oxide obtained from ferric oxide reduction preferentially reacts with aluminum oxide to form hercynite, and the reaction of ferrous oxide with silicon dioxide occurs only when there is surplus ferrous oxide after the exhaustion of aluminum oxide. When sintering temperature rises to 1473 K, hercynite further reacts with silicon dioxide to form mullite and ferrous oxide. Results presented in this work may throw a new light upon the separation of alumina and silica present in Al/Fe-bearing materials with low mass ratio of alumina to silica in alumina production.

Reductive acid leaching of cadmium from zinc neutral leaching residue using hydrazine sulfate

Zinc neutral leaching residue（ZNLR） from hydrometallurgical zinc smelting processing can be determined as hazardous intermediate containing considerable amounts of Cd and Zn which have great threats to the environment. The ZNLR contained approximately 35.99% Zn, 15.93% Fe and 0.26% Cd, and Cd mainly existed as ferrites in the ZNLR in this research. Reductive acid leaching of ZNLR was investigated. The effects of hydrazine sulfate concentration, initial sulfuric acid concentration, temperature, duration and liquid-to-solid ratio on the extraction of Cd, Zn and Fe were examined. The extraction efficiencies of Cd, Zn and Fe reached 90.81%, 95.83% and 94.19%, respectively when the leaching parameters were fixed as follows： hydrazine sulfate concentration, 33.3 g/L; sulfuric acid concentration, 80 g/L; temperature, 95 °C; duration of leaching, 120 min; liquid-to-solid ratio, 10 m L/g and agitation, 400 r/min. XRD and SEM-EDS analyses of the leaching residue confirmed that lead sulfate（Pb SO4） and hydrazinium zinc sulfate（（N2H5）2Zn（SO4）2） were the main phases remaining in the reductive leaching residue.

Reductive leaching of manganese oxide ores using waste tea as reductant in sulfuric acid solution

Manganese oxide ores from Gabon and Xiangxi were leached with waste tea as reductant in dilute sulfuric acid solution. The effects of waste tea dosage, concentration of sulfuric acid, liquid-to-solid ratio, leaching temperature and reaction time on leaching process were explored. The leaching efficiency of Gabonese manganese oxide ore reached almost 100% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 2.5 molFL, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching efficiency of Xiangxi manganese oxide ore reached 99.8% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 1.7 mol/L, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching process followed the internal diffusion controlled kinetic model, and the apparent activation energies of Gabonese manganese oxide ore and Xiangxi manganese oxide ore were calculated to be 38.2 kJ/mol and 20.4 kJ/mol, respectively. The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of XRD analysis and SEM analysis.

Kinetics of Reductive Leaching of Low-grade Pyrolusite with Molasses Alcohol Wastewater in H_2SO_4

The kinetics of reductive leaching of manganese from low grade pyrolusite in dilute sulfuric acid in the presence of molasses alcohol wastewater was investigated. The shrinking core model was applied to quantify the effects of reaction parameters on leaching rate. The leaching rate increases with reaction temperature, concentrations of H 2 SO 4 and organic matter in molasses alcohol wastewater increase and ore particle size decreases. The leaching process follows the kinetics of a shrinking core model and the apparent activation energy is 57.5 kJ·mol –1 . The experimental results indicate a reaction order of 0.52 for H2SO4 concentration and 0.90 for chemical oxygen demand (COD) of molasses alcohol wastewater. It is concluded that the reductive leaching of pyrolusite with molasses alcohol wastewater is controlled by the diffusion through the ash/inert layer composed of the associated minerals.

Reductive acid leaching of valuable metals from spent lithium-ion batteries using hydrazine sulfate as reductant

Hydrazine sulfate was used as a reducing agent for the leaching of Li,Ni,Co and Mn from spent lithium-ion batteries.The effects of the reaction conditions on the leaching mechanism and kinetics were characterized and examined.97%of the available Li,96%of the available Ni,95%of the available Co,and 86%of the available Mn are extracted under the following optimized conditions:sulfuric acid concentration of 2.0 mol/L,hydrazine sulfate dosage of 30 g/L,solid-to-liquid ratio of 50 g/L,temperature of 80℃,and leaching time of 60 min.The activation energies of the leaching are determined to be 44.32,59.37 and 55.62 k J/mol for Li,Ni and Co,respectively.By performing X-ray diffraction and scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy,it is confirmed that the main phase in the leaching residue is MnO2.The results show that hydrazine sulfate is an effective reducing agent in the acid leaching process for spent lithium-ion batteries.

Photoreductive degradation of sulfur hexafluoride in the presence of styrene

Sulfur hexafluoride （SF6） is known as one of the most powerful greenhouse gases in the atmosphere. Reductive photodegradation of SF6 by styrene has been studied with the purpose of developing a novel remediation for sulfur hexafluoride pollution. Effects of reaction conditions on the destruction and removal efficiency （DRE） of SF6 are examined in this study. Both initial styrene-to-SF6 ratio and initial oxygen concentration exert a significant influence on DRE. SF6 removal efficiency reaches a maximum value at the initial styrene-to-SF6 ratio of 0.2. It is found that DRE increases with oxygen concentration over the range of 0 to 0.09 mol/m^3 and then decreases with increasing oxygen concentration. When water vapor is fed into the gas mixture, DRE is slightly enhanced over the whole studied time scale. The X-ray Photoelectron Spectroscopy （XPS） analysis, together with gas chromatography-mass spectrometry （GC-MS） and Fourier Transform Infrared spectroscopy （FT-IR） analysis, prove that nearly all the initial fluorine residing in the gas phase is in the form of SiF4, whereas, the initial sulfur is deposited in the form of elemental sulfur, after photodegradation. Free from toxic byproducts, photodegradation in the presence of styrene may serve as a promising technique for SF6 abatement.

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

Growth of metallic iron particles during reductive roasting of boron-bearing magnetite concentrate

The growing characteristics of metallic iron particles during reductive roasting of boron-bearing magnetite concentrate under different conditions were investigated.The size of the metallic iron particles was quantitatively measured via optical image analysis with consideration of size calibration and weighted ratio of image numbers in the core,middle and periphery zones of cross-section of pellets.In order to guarantee the measurement accuracy,54 images were captured in total for each specimen,with a weighted ratio of 1:7:19 with respect to the core,middle and periphery section of the cross-section of pellets.Increasing reduction temperature and time is favorable to the growth of metallic iron particles.Based on the modification of particle size measurement,in terms of time(t)and temperature(T)a predicting model of metallic iron particle size(D),was established as:D=125−0.112t−0.2352T−5.355×10^−4t^2+2.032×10^−4t∙T+1.134×10^−4T^2.

Zinc Borohydride-Ionic Liquid: Stable and Efficient System for Reductive Reaction of Aldehydes with Primary Amines to Corresponding Secondary Amines

Ionic liquids（ILs） are attracting much attention in various fields of chemical synthesis, electrochemical applications, liquid-liquid extractions, as well as biotransformations. Among those fields, the application of ILs as the potential green solvent for a wide variety of synthetic processes is an area of intense researches. High yield, high selectivity, and good catalytic charac-teristics have usually been achieved. After the isolation of products, ILs can usually be recovered and recycled many times by simple treating procedures, such as, filtration, extraction, and dryness.

Effective synthesis of 5-amino-1-pentanol by reductive amination of biomass-derived 2-hydroxytetrahydropyran over supported Ni catalysts

A highly efficient and green process was developed for the synthesis of useful 5-amino-1-pentanol(5-AP)from biomass-derived dihydropyran by coupling the in situ generation of 5-hydroxypentanal(5-HP,via the ring-opening tautomerization of 2-hydroxytetrahydropyran(2-HTHP))and its reductive amination over supported Ni catalysts.The catalytic performances of the supported Ni catalysts on different oxides including SiO2,TiO2,ZrO2,γ-Al2 O3,and MgO as well as several commercial hydrogenation catalysts were investigated.The Ni/ZrO2 catalyst presented the highest 5-AP yield.The characterization results of the oxide-supported Ni catalysts showed that the Ni/ZrO2 catalyst possessed high reducibility and a high surface acid density,which lead to the enhanced activity and selectivity of the catalyst.The effect of reaction parameters on the catalytic performance of the Ni/ZrO2 catalyst was studied,and a high 5-AP yield of 90.8%was achieved in the reductive amination of 2-HTHP aqueous solution under mild conditions of 80℃and 2 MPa H2.The stability of the Ni/ZrO2 catalyst was studied using a continuous flow reactor,and only a slight decrease in the 5-AP yield was observed after a 90-h time-on-stream.Additionally,the reaction pathways for the reductive amination of 2-HTHP to synthesize 5-AP were proposed.

Reductive cyclodimerization of arylmethylidenemalononitriles promoted by samarium and catalytic amount of iodine： facile synthesis of cyclopentene derivatives

Samarium and a catalytic amount of iodine were used to obtain functionalized cyclopentenes by reductive dimerization followed by intramolecular cyclization of 1， 1-dicyanoalkenes under mild conditions.

Key genes expression of reductive tricarboxylic acid cycle from deep-sea hydrothermal chemolithoautotrophic Caminibacter profundus in response to salinity, pH and O_2

CO2 fixation pathway of Caminibacter profundus, a chemolithoautotrophic e-Proteobacteria from deep-sea hydrothermal vent, was determined and characterized by genetic and enzymatic analyses. Gene expression of key enzymes for CO2 fixation in response to salinity, pH and O2 in Medium 829 were also investigated. The results demonstrate that C. profundus contained aclB, porA and oorA, the genes encoding key enzymes of reductive tricarboxylic acid （rTCA） cycle. However, genes fragments of cbbL and cbbMencoding key enzyme of Calvin cycle were not recovered. Key enzymatic activities of ATP citrate lyase （ACL）, pyruvate： ferredoxin oxidoreductase （POR） and 2-oxoglutarate： ferredoxin oxidoreductase （OOR） were also present in C. profun- dus. The combination of genetic and enzymatic analyses confirm that C. profundus adopted rTCA cycle for carbon assimilation. The results of aclB and oorA relative expressions of C. profundus demonstrate that the ranges of environmental factors for high genes expression were sea salt 3.0%-5.0% （optimum 3.0%）, pH 5.0-6.5（optimum pH 6.5）, anaerobic to microaerobic conditions （optimum 1.0% 02）. Gene expression pat- terns under different conditions show similar patterns with bacterial growth, revealing that key rTCA cycle genes provided molecular basis for bacterial growth and propagation. Our results suggest that C. profun- dus could regulate key genes of rTCA cycle for carbon assimilation and energy metabolism in response to environmental fluctuations in hydrothermal vent.