Sluggish Migration Research Articles

Isotope Effects in a Li−S Battery: A New Concept

AbstractLithium‐sulfur battery represents an innovative technology for the next generation electrochemical energy storage, and insight into the fundamentals about its electrochemistry is a key to improved battery storage performance. With years of striving efforts, the interpretation of Li−S reaction mechanism has been extended down to a molecular level. Based on our recent work, we propose to re‐examine the Li−S electrochemistry at a (sub)atomic level. Both Li anode and S cathode are made up of mixtures of stable isotopes. Provided with almost the same nucleus structure yet different neutron numbers (and atomic mass), these isotopes could affect the thermodynamic and kinetic parameters of a chemical reaction, and energy storage capability of a Li−S battery. At the cathode, 34S forms stronger S−S bonds and shows higher tendency to react with Li than 32S, so that it helps to improve cathode reaction kinetics. High‐order polysulfide anions based on 34S show more sluggish migration in the ether electrolyte than the 32S‐based counterparts, which accounts for improved cycling stability of battery. Based on the electrochemical isotope effects of S, a conceptual technology for separating isotopes from natural chalcogen elements was introduced and shows a higher separation factor than the conventional methods.

Application of the Modified Method of Material Balance in Combination with Pyrolysis in Estimating the Hydrocarbon Generation Properties of the Bazhenov Formation, Western Siberia

The paper analyzes methods currently used to evaluate the generation parameters of source rocks and suggests a new modified variant of the van Krevelen diagram and an original algorithm for evaluating the hydrocarbon generation properties of bitumen-bearing rocks of the Bazhenov Formation and its analogues. This is done with the application of an integrated approach that employs pyrolitic data on core samples and material-balance calculations. Data on the most probable values of the hydrogen index and the degree of transformations of the original organic matter into naphtides are suggested to use to formally subdivide the possible types of the organic matter into five groups. The paper presents processed analytical data on 340 samples from wells at 13 hydrocarbon fields and three areas in the Khanty–Mansi Autonomous Area and calculated original contents of organic matter in the rocks before naphtide generation was initiated in them, the original and current generation potential values, and the amounts of generated and migrated naphtides. The generation properties of the samples taken at minimum distances from one another (sampling sites spaced 1–3 cm apart) are demonstrated to broadly vary. The broad scatter of the generation properties of the samples cannot be explained only by that they contained organic matter of two types: terra- and aquagenetic. The broad variations in the generation characteristics of the rocks are thought to be likely explained by specifics of their microbial processing and variations in the redox parameters of sedimentation and diagenesis. The two probable reasons for the high S1/S2 ratios of the bitumen-bearing rocks are (1) the open porosity of the rocks and (2) active generation and sluggish migration of naphtides generated in these rocks. The very high contents of organic matter of the rocks (up to 40–50% and more) are explained by that they contain epigenetic thiobitumen, which were produced when these rocks were affected by high-enthalpy hydrothermal fluids. The minimum and maximum specific generation of naphtides in rocks of the Bazhenov Formation and its analogues are evaluated (per 1 km2, per 25 m rock thickness). The specific migration of naphtides generated in the Bazhenov Formation and its analogues are compared with the specific (per 1 km2) geological hydrocarbon reserves in the Khanty-Mansi Autonomous Area.

Titanium Dioxide: From Engineering to Applications

Titanium dioxide (TiO2) nanomaterials have garnered extensive scientific interest since 1972 and have been widely used in many areas, such as sustainable energy generation and the removal of environmental pollutants. Although TiO2 possesses the desired performance in utilizing ultraviolet light, its overall solar activity is still very limited because of a wide bandgap (3.0–3.2 eV) that cannot make use of visible light or light of longer wavelength. This phenomenon is a deficiency for TiO2 with respect to its potential application in visible light photocatalysis and photoelectrochemical devices, as well as photovoltaics and sensors. The high overpotential, sluggish migration, and rapid recombination of photogenerated electron/hole pairs are crucial factors that restrict further application of TiO2. Recently, a broad range of research efforts has been devoted to enhancing the optical and electrical properties of TiO2, resulting in improved photocatalytic activity. This review mainly outlines state-of-the-art modification strategies in optimizing the photocatalytic performance of TiO2, including the introduction of intrinsic defects and foreign species into the TiO2 lattice, morphology and crystal facet control, and the development of unique mesocrystal structures. The band structures, electronic properties, and chemical features of the modified TiO2 nanomaterials are clarified in detail along with details regarding their photocatalytic performance and various applications.

Elution and internal migration of free amino acids in fish meats by soaking in sodium chloride or sorbitol solution

Elution and internal migration of free amino acids (FAA) in fish meats by soaking were investigated when the meat strips were soaked in various concentrations of sodium chloride (NaCl) or sorbitol solution. Rapid decrease of FAA in an earlier phase of soaking was followed by a mild one, irrespective of the kind and the concentration of soaking solution. The loss of FAA by soaking in NaCl solution was slightly larger than that in sorbitol solution. However, regardless of the kinds of soaking solution, the elution of FAA from fish meats by soaking was only dependent on the soaking time, independently of the concentration, namely osmotic pressure of the soaking solution. Conversely, sluggish migration of FAA from the inside to the surface of the meat strips proceeded by soaking. These results suggested that the elution of FAA from fish meats by soaking was driven by a simple diffusion from the surface of the meats to soaking solution, but it was regulated by sluggish migration rate of FAA in fish meats.