The synthesis,structure, and electrochemical properties of Li<Subscript>2</Subscript>FeSiO<Subscript>4</Subscript>-based lithium-accumulating electrode material

Different approaches to synthesis of Li₂FeSiO₄-based electrode materials for lithium intercalation, using low-cost and abundant Li-, Si-, and Fe-containing parent substances, are discussed. XRD, SEM, and a laser-diffraction analyzer of particle size were used for structure and morphology characterization of the composite electrode materials. Li₂FeSiO₄ was shown to be the main lithium-accumulating crystalline phase; minor LiFeO₂ and Li₂SiO₃ admixtures are also present. The material microparticles’ average size was shown to vary from tenths of micrometer to 1 μm. Larger objects sized ca. 2–4 μm are the microparticles’ agglomerates. The material electrochemical properties were studied by dc chronopotentiometry (galvanostatic charging–discharging) and cyclic voltammetry with potential linear sweeping. The initial reversible cycled capacity of the best samples is 170 mA h/g. The anodic and cathodic processes manifest obvious hysteresis caused by the presence of several different lithium ion energy states in the material; the transition between the states is kinetically hindered. The dependences of the specific capacity and its stability under cycling on the current load and the conductive carbon component content in the composite were elucidated.     

Regularities of oxygen and water thermal desorption from barium cerate doped by neodymium,samarium, and gadolinium

Processes of thermal desorption of oxygen molecules and water from BaCe_1–x M _x O_3–δ, where M= Nd, Sm, and Gd, presintered in air at the temperature of 650°C are studied. It is found that oxygen is desorbed only from neodymium–doped barium cerate and is almost not evolved from barium cerate doped by samarium and gadolinium. The amount of desorbed oxygen features a square dependence on cationic doping by neodymium. At similar degrees of cationic doping, the amount of water desorbed from neodymium–doped barium cerate is always lower than that from the cerate doped by samarium and gadolinium. The obtained experimental data on thermal desorption and analysis of literature data served as a basis for the conclusion as to the mixed valency of neodymium Nd(III)–Nd(IV) in BaCe_1–x Nd _x O_3–δ. In this case, at similar doping degrees x, the hydration degree of BaCe_1–x Nd _x O_3–δ is lower and the oxygen index is higher than in BaCe1_–x (Sm,Gd) _x O_3–δ. The differences become more pronounced at high degrees of cationic doping and must decrease at an increase in temperature.     

Quantitative Proteomic Analysis of Optimal Cutting Temperature (OCT) Embedded Core-Needle Biopsy of Lung Cancer

With recent advances in understanding the genomic underpinnings and oncogenic drivers of pathogenesis in different subtypes, it is increasingly clear that proper pretreatment diagnostics are essential for the choice of appropriate treatment options for non-small cell lung cancer (NSCLC). Tumor tissue preservation in optimal cutting temperature (OCT) compound is commonly used in the surgical suite. However, proteins recovered from OCT-embedded specimens pose a challenge for LC-MS/MS experiments, due to the large amounts of polymers present in OCT. Here we present a simple workflow for whole proteome analysis of OCT-embedded NSCLC tissue samples, which involves a simple trichloroacetic acid precipitation step. Comparisons of protein recovery between frozen versus OCT-embedded tissue showed excellent consistency with more than 9200 proteins identified. Using an isobaric labeling strategy, we quantified more than 5400 proteins in tumor versus normal OCT-embedded core needle biopsy samples. Gene ontology analysis indicated that a number of proliferative as well as squamous cell carcinoma (SqCC) marker proteins were overexpressed in the tumor, consistent with the patient’s pathology based diagnosis of “poorly differentiated SqCC”. Among the most downregulated proteins in the tumor sample, we noted a number of proteins with potential immunomodulatory functions. Finally, interrogation of the aberrantly expressed proteins using a candidate approach and cross-referencing with publicly available databases led to the identification of potential druggable targets in DNA replication and DNA damage repair pathways. We conclude that our approach allows LC-MS/MS proteomic analyses on OCT-embedded lung cancer specimens, opening the way to bring powerful proteomics into the clinic.

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Application of Atmospheric Solids Analysis Probe Mass Spectrometry (ASAP-MS) in Petroleomics: Analysis of Condensed Aromatics Standards,Crude Oil,and Paraffinic Fraction

Atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful tool for analysis of solid and liquid samples. It is an excellent alternative for crude oil analysis without any sample preparation step. Here, ASAP-MS in positive ion mode, ASAP(+)-MS, has been optimized for analysis of condensed aromatics (CA) standards, crude oil, and paraffinic fraction samples using a Synapt G2-S HDMS. Initially, two methodologies were used to access the chemical composition of samples: (1) using a temperature gradient varying from 150 to 600 °C at a heating rate of 150 °C min^–1, and (2) with constant temperature of 300 and 400 °C. ASAP(+)-MS ionized many compounds with a typical petroleum profile, showing a greater signals range of m/z 250–1300 and 200–1400 for crude oil and paraffin samples, respectively. Such performance, mainly related to the detection of high molecular weight compounds (>1000 Da), is superior to that of other traditional ionization sources, such as ESI, APCI, DART, and DESI. Additionally, the CA standards were identified in both forms: radicals, [M]^+?, and protonated cations, [M + H]⁺, with minimum fragmentation. Therefore, ASAP was more efficient in accessing the chemical composition of nonpolar and polar compounds. It is promising in its application with ultrahigh resolution MS instruments, such as FT-ICR MS and Orbitrap, since molecular formulas with greater resolution and mass accuracy (<1 ppm) would be assigned.

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Gas mixture flow in nanoporous media in the presence of surface forces. The dusty-gas model

The dusty-gas model has been generalized to the case of gas mixture flow in nanoporous media under the conditions of the action of surface forces. A basic set of transport equations has been derived proceeding from kinetic equations for a gas mixture and dust particles. To take into account the surface forces, the interaction between a gas and dust particles has been represented as a sum of a long-range potential, which reflects the surface forces, and a short-range potential, which describes gas molecule scattering on the surface of pore walls. The contribution of the long-range component has been taken into account in the self-consistent approximation, while the short-range component has been considered in the standard manner. The surface forces have been shown to have a substantial effect on the transfer of mixed gases through porous bodies; in particular, it becomes possible to separate mixture components due to different potentials of the interaction of their molecules with pore surface.     

Synthesis of hydrated tungsten(VI) oxide sols by peptization

A method has been developed for the synthesis of hydrated tungsten oxide hydrosols, with this method being based on potassium tungstate hydrolysis followed by peptization of the formed precipitate. The influence of the conditions of precipitation, aging, and washing of the precipitate on the particle phase composition and shape and the degree of precipitate peptization has been studied. Hydrosol-particle sizes have been determined by different methods. It has been found that the dispersed phase of the hydrosols consists mainly of platelike particles of hydrated tungsten oxide WO₃ · 2H₂O with a number-average size of 52 nm. The sols are stable to aggregation in a pH range of 3.0–4.5. The zeta potential of the particles ranges from–33 to–38 mV.     

Adsorption of nonionic surfactant on porous and nonporous poly(ethylene terephthalate) films

The application of surfactants in the chemical etching of track membranes enables one to control their pore shape. To find out the mechanism of the surfactant action on the track etching in the nanometer range of pore sizes, the adsorption of a nonionic surfactant (polyoxyethyelene-4-nonylphenyl ether) on porous and nonporous poly(ethylene terephthalate) films has been studied. The experimental results have been analyzed in comparison with the data previously obtained on the adsorption of an anionic surfactant on similar films. It has been concluded that the behaviors of anionic and nonionic surfactants in negatively charged pores about 100 nm in radius are strongly different due to the electrostatic exclusion of co-ions from the pores, which is of significance only for compounds dissociating into ions.     

Food safety assurance using methods of chemical analysis

A review of state-of-the-art methods of sample preparation and chemical analysis for the control of contaminants in foodstuffs and food raw materials is presented. The main achievements and performance characteristics of methods for the determination of pesticides and veterinary drugs, their metabolites, natural toxins, trace amounts of chemical elements, first of all toxic, allergens, food additives, and contaminants from packaging materials in foodstuffs and for the identification of falsifications by methods of chemical analysis are considered.     

Chromatographic determination of nitrophenols in aqueous media after two-stage preconcentration using an N-vinylpyrrolidone-based polymer

Two-stage procedures for the preconcentration of nitrophenols (4-nitrophenol, 2,4- and 2,5-dinitrophenol, and 2,4,6-trinitrophenol) from aqueous solutions are proposed. At the first stage, the preconcentration and desorption of nitrophenols under dynamic conditions is carried out. At the second stage, depending on the nature of the desorption solution, the eluate is evaporated (acetonitrile) or saturated with ammonium sulfate and extracted with acetone (aqueous NH₃ solution). The concentration factors are 4000 and 910, respectively. Nitrophenols are determined in concentrates by thin layer chromatography and HPLC, the limits of detection are 1.0–1.8 and 0.25–0.45 μg/L, respectively. The duration of analysis is 200 min.     

Determination of gold and palladium in rocks and ores by atomic absorption spectrometry using two-stage probe atomization

The efficiency of two-stage probe atomization for the determination of gold and palladium in geological samples by electrothermal atomic absorption spectrometry is studied. The effects of temperature–time program and the position of the probe in an atomizer on the fractionation of sample components and the magnitude of the analytical signal are studied. It is demonstrated that gold and palladium can be quantitatively determined by atomic absorption spectrometry in rocks and ores, using a two-stage probe atomization with the limits of detection for gold and palladium 0.01 and 0.04 g/t, respectively.