Investigation Of Reactions Research Articles

Direct Evidence of Reversible Changes in Electrolyte and its Interplay with LiO2 Intermediate in Li-O2 Batteries.

Lithium-oxygen batteries show promising energy storage potential with high theoretical energy density; however, further investigation of chemical reactions is required. In this study, experimental Raman and theoretical analyzes are performed for a Li-O2 battery with LiClO4/dimethyl sulfoxide (DMSO) electrolyte and carbon cathode to understand the role of intermediate species in the reactional mechanism of the cell using a high donor number solvent. Operando Raman results reveal reversible changes in the DMSO bands, in addition to the formation and decomposition of Li2O2. On discharge, a decrease in DMSO polarizability is observed and bands of DMSO-Li+-anion interactions are evidenced and supported by abinitio density functional theory (DFT) calculations. Molecular dynamics (MD) force field simulations and operando Raman show that DMSO interacts with LiO2(sol), highlighting the stability of the electrolyte compared to the interaction with reactive . On charging, the presence of Li+ indicates the formation of a lithium-deficient phase, followed by the release of Li+ and oxygen. Therefore, this study contributes to understanding the discharge/charge chemistry of a Li-O2 cell, employing a common carbon cathode and DMSO electrolyte. The combination of a simple characterization technique in operando mode and theoretical studies provides essential information on the mechanism of Li-O2system.

Clustering in gallium ion beam sputtered compound materials driven by bond strength and interstitial/vacancy reaction

The investigation of chemical reactions during ion irradiation is a frontier for the study of the ion–material interaction. In order to probe the chemistry of ion produced nanoclusters, valence electron energy loss spectroscopy (VEELS) was exploited to investigate Ga+ ion damage in Al2O3, InP, and InGaAs, where each target material has been shown to react differently to the interaction between impinging ions, recoil atoms, and vacancies: metallic Ga, ternary InGaP clusters, and metallic In clusters are formed in Al2O3, InP, and InGaAs, respectively. Supporting simulations based on Monte Carlo and crystal orbital Hamiltonian calculations indicate that the chemical constitution of cascade induced nano-precipitates is a result of a competition between interstitial/vacancy consumption rates and preferential bond formation due to differing bond strengths.

Synthesis, X-Ray Diffraction, DFT and Hirshfeld Surface Studies of 9-(4-Hydroxyphenyl-Tetramethyl-Hexahydro-1H-Xanthene-1,8(2H)-Dione

9-(4-hydroxyphenyl-tetramethyl-hexahydro-1H-xanthene-1,8(2H)-dione (OH-X) was synthesized and characterized experimentally using X-ray diffraction, FT-IR, 1H, 13 C NMR, and UV-Vis spectra, and theoretically using DFT calculations. To look at stability, different physicochemical properties have been compared. The most stable optimized structure was discovered using the B3LYP/6-311++G(d,p) basis set, followed by FTIR and NMR investigation. Further details on the estimation of the electronic transitions in the UV-Vis spectra were provided by TD-DFT analysis. The Hirshfeld surface analyses were presented and discussed, as well as the energy framework calculations. The estimated maximum wavelength (λ) absorbance and the band-gap energy of OH-X were computed for various solvents and compared to the outcomes of experiments. Investigations of chemical reactivity, MEP map, and surface area maps were also carried out. To show electron delocalization in the molecule, electron localization function (ELF) and the local orbital localizer (LOL) were used. Other topics included topological and Mulliken charge distribution studies. Utilizing certain vibrational modes, the vibrational assignments were accomplished and experimental data was compared. The docking studies were utilized to investigate the interactions of the ligand (OH-X) with certain protein targets, suggesting that OH-X could be employed as a potential cytotoxic and antibacterial agent. OH-X may be considered a potential medicinal molecule as a result of the current research. In terms of geometric and spectroscopic features, the findings from the experimental and theoretical were highly comparable.

Software‐guided Microfluidic Reaction Calorimeter Based on Thermoelectric Modules

AbstractA software‐guided, continuous reaction calorimeter based on thermoelectric modules for direct heat flux measurements is presented. Sensors and actuators of the calorimeter's setup are implemented within a lab automation system, which enables the automated calibration of the heat flux sensors and investigations of chemical reactions through sequential function charts. Functionality of the calibration is shown by heat transfer experiments. Additionally, the calorimeter's performance is demonstrated by good agreement of conducted neutralization experiments with literature data.

Investigation of chemical reactions on wire cloth micro heat exchangers

Investigation of chemical reactions on wire cloth micro heat exchangers

Investigation of chemical reaction during sodium alginate drop impact on calcium chloride film

The objective of this work is to study the chemical reaction between sodium alginate drop and calcium chloride film and instantaneous formation of calcium alginate gel. The complexity of this work is the simultaneous effect of both liquid and solid surface on drop impact gelation process. The sodium alginate concentration in the drop fluid, liquid film thickness, and drop impingement height are varied and the observations are captured using a high speed camera. Several interesting phenomena like splashing and jet break up occur depending on the drop impingement velocity, drop concentration, and film thickness. Crosslinking reaction and mixing mechanisms are schematically explained accounting the role of capillary wave propagation within the liquid film. A mathematical model on drop spreading on the solid surface after penetrating the liquid film is developed to predict the theoretical gel length for ultrathin and thin film regimes. Maximum spreading diameter of the drop postimpact on the liquid film is predicted from the model. However, the experimentally measured solidified gel length deviates from the theoretical values and these deviations are utilized to measure the rate of crosslinking gelation and instantaneous solidification. Different hydrodynamic parameters such as the crater depth, crater contact time, and crater dissipation energy are evaluated for the dynamics of gelation. Finally, the kinetics of gelation with the variation of liquid film thickness are determined for alginate drop concentrations and drop impingement heights.

Numerical Investigation of Chemical Reaction and Heat Source on Radiating MHD Stagnation Point Flow of Carreau Nanofluid with Suction/Injection

This research work is focused on the effects of combined heat and mass transfer on MHD stagnation point flow of Carreau nanaofluid embedded in porous medium with heat source. Thermal radiation and chemical reaction are also taken into account. The governing non-linear PDEs are transformed into a set of non-linear coupled ODEs which are then solved numerically by using the Runge– Kutta–Fehlberg fourth–fifth order method along shooting technique. The graphical and tabular results elucidate the influence of different non-dimensional governing parameters on the velocity, temperature and concentration fields along with the wall friction, local Nusselt and Sherwood numbers. We found the dual nature of the solutions for suction and injection cases. A good agreement of the present results has been observed by comparing with the existing literature results.

Investigation of chemical reactivity and active components of ambient VOCs in Jinan, China

An analysis of 55 volatile organic compounds (VOCs) in the atmosphere was conducted to identify the active components and to determine the potential reactivity using 2 years of air pollution monitoring data in a city in east of China. The results show that the atmospheric hydroxyl radical consumption rate (L OH) and ozone forming potential (OFP) of the VOCs corresponded directly to the concentration profiles. The values of L OH and OFP were found to be higher in summer than other seasons. The hydroxyl radical loss rate constant (k OH) of the VOCs by regression analysis was much higher than that of ethylene, while the maximum incremental reactivity (MIR) of VOCs was similar to that of ethylene. Alkenes were found to be the key active components identified in atmospheric pollution, and vehicle exhaust was considered to be the major source of the VOCs in Jinan’s atmosphere.

Investigation of chemical reactivity at the M/CuO interfaces (where M = Fe, Co, or Ni)

The chemical reactivity at the M/CuO interfaces (where M is Fe, Co, or Ni) has been studied. Thin films (of thickness 0.5 nm) of the metal M were deposited at room temperature on the CuO substrate by the e-beam method. The interfaces have been characterized in situ by the technique of x-ray photoelectron spectroscopy. The 2p core level regions of the metals have been investigated. The spectral data show considerable reactivity at the interfaces formed at room temperature. The core level peaks of the metal M have been observed to shift to the high binding energy side. Intense satellites appear on the high binding energy side of these core level peaks. The spectral data have been compared with those of the oxidized metal. These spectral features conform to each other confirming the formation of the metal oxide. The satellite structure in the copper region was observed to disappear, and the spectral features approach those of elemental copper after the deposition of the metallic overlayer. The data, therefore, suggest that the copper oxide gets reduced to elemental copper, and the metal M is oxidized to the metal oxide. The presence of the high binding energy satellite has been used to identify the phase of the metal oxide formed at the interface. The uniformity of the initial 0.5 nm overlayer has also been investigated. A second overlayer of 0.5 nm was deposited over the first layer. The characterization of these samples showed core level peaks at the elemental positions. The spectral features correspond to the presence of unreacted metal in these samples. The content of this unreacted metal was determined and is observed to increase in the order from iron to cobalt to nickel. The investigation shows room temperature chemical reactivity at the M/CuO interface and provides a new method to prepare sub-nano-oxide films of iron, cobalt, and nickel.

The Bridge Connecting Gas‐Phase and Solution Chemistries

Charged wings for flying fish: Mass spectrometry allows the investigation of chemical reactions at the molecular level with ease, speed, selectivity, sensitivity, and great flexibility. Modern mass spectrometry provides a bridge that allows chemical reactions that occur in the gas phase to be studied in solution, and vice-versa (see picture).

Accurate modeling of molecular crystal through dispersion-corrected density functional theory (DFT-D) method

ABSTRACTCrystal structure, pressure response, and polymorph transformation were investigated for crystalline indole through dispersion-corrected density functional theory (DFT-D) method. An accurate, nonempirical method (as in the latest implementations of CASTEP) is used to correct for the general DFT scheme to include van der Waals interactions important in molecular crystals. Ambient structural details, including space group symmetry, density, and fine structural details, such as bicyclic angles, have been reproduced to within experimental accuracy. Pressure response of the structure was obtained to isostatic pressure up to 25 GPa, in increments of 1 GPa. Evolution of space group symmetry and the bicyclic angle were mapped as a function of pressure. A previously unknown phase transformation has been identified around 14 GPa of isostatic pressure. Total energies of the phases before and after phase transformation are nearly identical, with a phase transformation barrier of 0.9 eV. The study opens up the door to reliable DFT investigations of chemical reactions of crystalline aromatic systems under high pressure (e.g. formation of amorphous sp3 hybridized phases).

DNA Strands from Denatured Duplexes are Translocated through Engineered Protein Nanopores at Alkaline pH

Nanopores are under development for the detection of a variety of analytes and the investigation of chemical reactions at the single molecule level. In particular, the analysis of nucleic acid molecules is under intense investigation, including the development of systems for rapid, low-cost DNA sequencing. Here, we show that DNA can be translocated through an engineered alphaHL protein pore at pH 11.7, a value at which dsDNA is denatured. Therefore, the alphaHL pore is sufficiently stable to entertain the possibility of direct nanopore sequencing of genomic dsDNA samples, which are more readily obtained and handled than ssDNA.

In Situ Investigations of Chemical Reactions on Surfaces by X-Ray Diffraction at Atomospheric Pressures

AbstractCatalytic reactions occurring at metal surfaces and nanoparticles have been an established research field for decades, yielding information on adsorption sites and reaction pathways under ultrahigh-vacuum conditions. Recent experimental developments have made it possible to perform well-controlled in situ surface x-ray diffraction measurements from single-crystal surfaces and nanoparticles under industrially relevant conditions. In this way, a new understanding of atomic-scale processes at surfaces and nanoparticles occurring during catalytic reactions under realistic conditions has been gained. In particular, the identification of the formation of thin oxides on model catalysts and their role in oxidation reactions demonstrates the importance of in situ probes under relevant conditions.

Application of radiochemical technique in the investigation of chemical reaction at low temperature

Radiochemical technique was used to investigate cryogenic chemical reaction. By introducing reactants of H and T into liquid 3H through 3He(n,p)T reaction, behaviors of H+T→HT and T+T→T2 were investigated under pressurized condition. Within saturated vapor pressure upto 0.61 Mpa, the isotope ratio of HT/T2 changed. It was suggested that the change of HT/T2 was attributed to bubble formation and chemical potential in liquid helium.

Neutron Scattering for Materials Science

The work is a review paper concerning application of neutron diffraction methods for condensed matter investigations and for characterizing modern materials, namely for crystal and magnetic structures determination, small-angle scattering, investigations of chemical reactions and some practical applications. It addresses briefly a few of more prominent techniques that are important for materials scientists. In the first part of the work information on the methods and ways of interpretation of obtained results is given. Then the results for some chosen compounds are presented.

Investigation of Chemical Reactions in Solution Using API‐MS

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Investigation of chemical reactions in solution using API-MS

The general concepts, advantages, and applications of on-line and off-line screening to organic reaction mechanistic studies applying API-MS are reviewed. An overview is presented of the development and the present stage of connected microreactors to API ion-sources. Examples of the successful application of API in revealing, elucidating, and helping to consolidate several proposed mechanisms of organic reactions are summarized. Finally, a variety of outstanding features and advantages that make API-MS the most suitable tool for the fast screening of intermediates directly from solution, and the exceptional gains in chemical information for organic chemists are also emphasized.

U-Zr合金／高速炉用被覆材の反応性確認試験

U-Zr合金／高速炉用被覆材の反応性確認試験

Potentials of variable–variable and sample–sample, generalized and statistical, two-dimensional correlation spectroscopies in investigations of chemical reactions

Generalized and statistical variable–variable (VV) and sample–sample (SS) two-dimensional (2D) correlation spectroscopies are used to investigate a three-band spectral model that represents a simple consecutive chemical reaction. Generalized and comprehensive linear algebra basis, which is essential for the analysis of three-component systems by 2D correlation, is provided. It is found from the analysis of slice spectra of synchronous and asynchronous VV correlation maps of the model that the spectral and concentration influences of an intermediate can be identified and related to the real characteristics of the intermediate. 2D correlation spectroscopy may be effectively employed to give a semiquantitative portrayal of a chemical reaction. The results of statistical 2D correlation spectroscopy are not directly related to the bands or concentration profiles, but are concerned with simple trends in intensity changes in the spectra. It seems that for all consecutive reactions where the mass of the system is entirely preserved, SS correlation maps may be the same, independent of spectroscopic techniques for monitoring reactions. If this is the case, the results of the present study offer a prospect for automatic determination of reaction constants in successive reactions by the means of 2D correlation spectroscopy.

ChemInform Abstract: A Chemical Synthesis of Porphobilinogen Imitating the Pathway Proposed by Shemin for the Biosynthesis: Comparing Inhibition Studies with Investigations of Chemical Reactivity

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.