Tayloreskildsen5074

Primary amines and benzothiophene-3-carboxaldehyde were reacted to give four large, bulky imine ligands. These imine ligands were reacted with a tetramethyl platinum dimer and by heteroatom-assisted C-H activation, both monometalated compounds and bismetalated compounds were synthesized. In all cases, five-membered platinacycles were formed. The compounds were characterized by NMR spectroscopy, and one bismetalated compound was characterized by single-crystal X-ray diffraction. The UV-vis absorption and emission spectra and the excited-state lifetimes were recorded for these complexes. Density functional theory (DFT) and time-dependent-DFT calculations were performed to aid in the assignment of the absorption and emission spectra of the newly synthesized complexes.Recently, a new class of two-dimensional (2D) materials, called MXene, consisting of layers of transition-metal carbides and nitrides/carbonitrides has been introduced. MXene, a multifunctional material with hydrophilic nature and excellent electrical conductivity and chemical stabilities, can be applied in diverse research areas such as energy harvesting and its storage, water purification, thermal dissipation, and gas sensing. To achieve the best quality of MXene, optimization of some important synthetic parameters is highly required such as an optimized etchant concentration to remove an "A" element from the MAX phase and sonication time for the efficient exfoliation of MXene flakes. Besides, there is a need to disclose that particular solvent through which intercalation can easily be achieved. In this work, we optimized the abovementioned critical parameters for the synthesis of good-quality MXene. Our results clearly explain the variations in the quality of MXene under applied etchant concentrations, solvents for better intercalation, and optimization of sonication time for better exfoliation. The obtained results suggest that 30% HF as an etchant, dimethyl sulfoxide (DMSO) as a solvent, and 135 min as the sonication time are effective parameters for the synthesis of good-quality MXene. We expect that this report will be helpful for the young research community to synthesize good-quality MXene with the required properties.Remediation of organic pollutant matrixes from wastewater by photodegradation using different heterojunctions is extensively studied to improve performance for potential application. Brilliant black (BB) and p-nitrophenol (PNP) have been detected in the environment and implicated as directly or indirectly carcinogenic to human health. This work analyzes their elimination from aqueous solutions under visible-light irradiation with composites of cobalt(II, III) oxide and bismuth oxyiodides (Co3O4/Bi4O5I2/Bi5O7I). The synthesized nanomaterial properties were investigated using various techniques such as BET, SEM/EDS, TEM, XRD, FTIR, PL, and UV-vis. All the nanocomposites absorbed in the visible range of the solar spectrum with band gaps between 1.68 and 2.79 eV, and the specific surface area of the CB2 composite increased by 35.8% from that of Bi4O5I2/Bi5O7I. There was an observed massive reduction in the rate of electron and hole recombination, and the band gaps of the composites decreased. The mineralization of PNP and BB was followed by determination of the total organic carbon with reductions of 93.6 and 83.7%, respectively. The main active species were the hydroxyl radicals, while the superoxide anion radical and generated holes were minor as confirmed by radical trapping experiments. The optimum pHs for degradation of PNP and BB were 9.6 and 5.3, respectively. Pitstop 2 The enhanced performance of the catalyst was due to C-scheme heterojunction formation that reduced the electron and hole recombination rate and was attributed to strong adsorption of the pollutants on the photocatalyst active surface. The nanocomposite is apposite for solar energy-driven remediation of organic pollutants from environmental aqueous samples.In this paper, the influence of Stefan flow on different reactivity coke solution loss reaction (Ccoke + CO2 = 2CO) at different temperatures were analyzed and compared to deeply understand the mechanism of the coke solution loss reaction. Isothermal experiments of carbon dioxide gasification with Coke A (low reactivity), Coke B (medium reactivity), and Coke C (high reactivity), respectively, were carried out at 1100-1300 °C. After calculation, it is concluded that the external diffusion coefficients and the mass transfer coefficients with Stefan flow of three kinds of coke were decreased, and their minimum average deviations with and without Stefan flow were 44.57/43.27/43.23 and 42.57/39.47/39.15%, respectively. As the coke reactivity increased, the diffusion and mass transfer capacity of carbon dioxide with Stefan flow in the boundary layer decreased. The carbon dioxide concentration on the outer surface of three kinds of coke with Stefan flow was less than that without Stefan flow. The influence of Stefan flow on carbon dioxide concentration on the outer surface of coke was increased with the increase of coke reactivity. The area of carbon dioxide concentration region in the three kinds of coke declined after modification, and the deviations of the carbon dioxide concentration region area before and after modification of three kinds of coke ranged from 6.62 to 22.85%, 7.74 to 25.17%, and 8.62 to 26.74%. The influence of Stefan flow on the carbon dioxide concentration region increased as coke reactivity increased.Serratia marcescens chitinase A (SmChiA) processively hydrolyzes recalcitrant biomass crystalline chitin under mild conditions. Here, we combined multiple sequence alignment, site-saturation mutagenesis, and automated protein purification and activity measurement with liquid-handling robot to reduce the number of mutation trials and shorten the screening time for hydrolytic activity improvement of SmChiA. The amino acid residues, which are not conserved in the alignment and are close to the aromatic residues along the substrate-binding sites in the crystal structure, were selected for site-saturation mutagenesis. Using the previously identified highly active F232W/F396W mutant as a template, we identified the F232W/F396W/S538V mutant, which shows further improved hydrolytic activity just by trying eight different sites. Importantly, valine was not found in the multiple sequence alignment at Ser538 site of SmChiA. Our combined approach allows engineering of highly active enzyme mutants, which cannot be identified only by the introduction of predominant amino acid residues in the multiple sequence alignment.Based on experimental data of both batch and continuous enzyme-catalyzed kinetic resolutions of (±)-trans-1,2-cyclohexanediol in supercritical carbon dioxide, kinetic models of increasing complexity were developed to explore the strengths and drawbacks of various modeling approaches. The simplest, first-order model proved to be a good fit for the batch experimental data in regions of high reagent concentrations but failed elsewhere. A more complex system that closely follows the true mechanism was able to fit the full range of experimental data, find constant reaction rate coefficients, and was successfully used to predict the results of the same reaction run continuously in a packed bed reactor. Care must be taken when working with such models, however, to avoid problems of overfitting; a more complex model is not always more accurate. This work may serve as an example for more rigorous reaction modeling and reactor design in the future.We report the formation of cubic and tetragonal BaSrN3 at 100 GPa using an ab initio structure search method. Pressure ramping to 0 GPa reveals a reaction pressure threshold of 4.92 and 7.23 GPa for the cubic and tetragonal BaSrN3, respectively. The cubic phase is stabilized by coulombic interaction between the ions. Meanwhile, tetragonal BaSrN3 is stabilized through an expansion of the d-orbital in Ba and Sr atoms that is compensated by delocalization of π-electrons in N through reduction of π overlap. Elastic properties analysis suggests that both phases are mechanically stable. The structures also have high melting points as predicted using an empirical model, and all imaginary modes vanishes at about 2000 K. These results have significant implication for the design of cleaner and environmentally friendly high energy density materials.The growth of sputtered GaN at low temperature is strongly desired to realize the dissemination of low-cost GaN high electron mobility transistor devices for next-generation communication technology. In this work, the roles of atomic nitrogen (N)/hydrogen (H) in GaN film growth on AlN/sapphire substrates by chemically assisted dual source sputtering are studied at a low growth temperature of 600 °C under a pressure of 2 Pa using vacuum ultraviolet absorption spectroscopy. The lateral growth was strongly enhanced with an appropriate H/N flux ratio of 1.9 at a GaN growth rate of ∼1 μm h-1. X-ray photoelectron spectroscopy measurements indicated that N removal from the grown GaN surface by atomic hydrogen promoted the migration of Ga. A smooth GaN surface was achieved at a suitable N/Ga supply ratio of 53 and a H/N ratio of 1.9 with the addition of 0.5% chlorine to the Ar sputtering gas.This paper involved conducting an experimental investigation on the effects of exhaust gas recirculation (EGR) and spark timing on the combustion, performance, and emission characteristics of a China-VI heavy-duty, natural gas engine fueled with high-methane content. The results showed that increasing the EGR rate extends the spark timing range and slows the combustion. This then increases ignition delay, prolongs combustion duration, and decreases heat release rate. Peak in-cylinder pressure (PCP) and indicated thermal efficiency (ITE) initially increase because of higher boost pressure with increasing EGR rate. However, as EGR rate increases further, PCP and ITE begin to decrease because of the deviation of combustion phasing. Lower in-cylinder temperature caused by higher EGR rate may cause nitrogen oxide (NOx) emissions to reduce significantly, while total hydrocarbon (THC) and carbon monoxide (CO) emissions increase, and THC emissions could increase exponentially at high EGR rates. In-cylinder pressure, temperature, and heat release rate increase with early spark timing, but the rate of increase is reduced at higher engine speeds. Early spark timing causes THC and CO emissions to increase at part-load conditions, whereas there is little change at full-load conditions. NOx emissions also increase with early spark timing because of the higher in-cylinder temperature.Herein, a 3.0%-Au/Sr0.70Ce0.20WO4 sample was prepared for the photocatalytic reduction of the Cr2O72- ion. The photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectra. The Sr0.70Ce0.20WO4 sample presented a photocatalytic reduction activity that is better than those of the Ce-doped sample and the intrinsic sample. Thereafter, different metal elements, Cu, Ag, Au, and Pt, were used as cocatalysts, which were loaded on the Sr0.70Ce0.20WO4 sample. The 3.0%-Au/Sr0.70Ce0.20WO4 photocatalyst showed optimal photocatalytic reduction activity in a 8 vol % methanol solution (pH = 7) under visible light irradiation. The kinetic constant of the optimal one is 0.0039 min-1, which is 1.86 times that of the Sr0.70Ce0.20WO4 sample. The photocatalyst is stable enough after a 24 h photocatalytic experiment.