Reactions of singly-reduced ethylene carbonate in lithium battery electrolytes: a molecular dynamics simulation study using the ReaxFF

We have conducted quantum chemistry calculations and gas- and solution-phase reactive molecular dynamics simulation studies of reactions involving the ethylene carbonate (EC) radical anion EC(-) using the reactive force field ReaxFF. Our studies reveal that the substantial barrier for transition from the closed (cyclic) form, denoted c-EC(-), of the radical anion to the linear (open) form, denoted o-EC(-), results in a relatively long lifetime of the c-EC(-) allowing this compound to react with other singly reduced alkyl carbonates. Using ReaxFF, we systematically investigate the fate of both c-EC(-) and o-EC(-) in the gas phase and EC solution. In the gas phase and EC solutions with a relatively low concentration of Li(+)/x-EC(-) (where x = o or c), radical termination reactions between radical pairs to form either dilithium butylene dicarbonate (CH(2)CH(2)OCO(2)Li)(2) (by reacting two Li(+)/o-EC(-)) or ester-carbonate compound (by reacting Li(+)/o-EC(-) with Li(+)/c-EC(-)) are observed. At higher concentrations of Li(+)/x-EC(-) in solution, we observe the formation of diradicals which subsequently lead to formation of longer alkyl carbonates oligomers through reaction with other radicals or, in some cases, formation of (CH(2)OCO(2)Li)(2) through elimination of C(2)H(4). We conclude that the local ionic concentration is important in determining the fate of x-EC(-) and that the reaction of c-EC(-) with o-EC(-) may compete with the formation of various alkyl carbonates from o-EC(-)/o-EC(-) reactions.     

Miscibility and interfacial property studies of the blends of ethyl cellulose with copolyamide6/66/1010

Interfacial properties governing reverse osmosis separations were studied by using liquid chromatography data with respect to ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends. The miscibility of ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends was investigated by using differential scanning calorimetry (DSC) and Fourier transform infrared, while the interfacial properties of the blends, including the interfacial adsorption, hydrophobicity, polar and non-polar parameters and β-parameters, were studied by using liquid chromatography. The results show that EC and PA-130 are miscible at compositions of (80/20), (70/30) and (50/50). The hydrophobicity of EC/PA-130 increases with the of PA-130 content. The EC/PA-130(70/30) is superior to the other blends for separating non-dissociable polar organic solute and is more suitable for use as desalting membrane material. It seems that liquid chromatography is an effective tool for studying the interfacial properties of polymer blend materials and selecting high performance of membrane materials.     

Influence of Organic Additive on the Morphological, Electrical and Electrochromic Properties of Sol-Gel Derived WO3 Coatings

The WO₃ electrode is ubiquitous in an electrochromic device (ECD) and is a common choice as the electrochromic (EC) layer. EC films were deposited on different substrates by spin coating using peroxotungstic acid based precursor solutions followed by appropriate thermal treatment. Many properties of the films, including some of the EC properties dependant on microstructure of the films, were found to be modified by the addition of small amounts of organic acid to the precursor solution. A study of structural, electrical and electrochromic properties of films cast by using precursor solution comprising 0 to 10 wt% of oxalic acid dihydrate (OAD) was carried out in terms of surface morphology, electrical resistance, structure and EC response. The important findings are that the addition of oxalic acid to the precursor solution results in films with excellent EC properties, devoid of cracks and decreases their dc electrical resistance.     

Oxidation induced decomposition of ethylene carbonate from DFT calculations - importance of explicitly treating surrounding solvent

The oxidation induced reactions of the common lithium battery electrolyte solvent ethylene carbonate (EC) have been investigated for EC(2) using density functional theory and for selected reaction paths using M?ller-Plesset perturbation theory (MP4). The importance of explicitly treating at least one solvent molecule interacting with EC during oxidation (removal of an electron) on the EC oxidation potential and decomposition reactions was shown by comparing oxidation of EC and EC(2). Accuracy of DFT results was evaluated by comparing with MP4 and G4 values for oxidation of EC. The polarized continuum model (PCM) was used to implicitly include the rest of the surrounding solvent. The oxidation potentials of EC(2) and EC(4) were found to be significantly lower than the intrinsic oxidation potential of an isolated EC and also lower than the oxidation potential of EC-BF(4)(-). The exothermic proton abstraction from the ethylene group of EC by the carbonyl group of another EC was responsible for the decreased oxidative stability of EC(2) and EC(4) compared to EC. The most exothermic path with the smallest barrier for EC(2) oxidation yielded CO(2) and an ethanol radical cation. The reaction paths with the higher barrier yielded oligo(ethylene carbonate) suggesting a pathway for the experimentally observed poly(ethylene carbonate) formation of EC-based electrolytes at cathode surfaces.     

Properties of passivation film on carbon electrode in LiPF6/EC+DEC electrolytes

The co-solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) was used to investigate the decomposition of electrolyte in Li-ion batteries. The electrolyte solutions were prepared by mixing in various volume ratios from pure DEC to 7:3 (EC:DEC). The potentials at which they are decomposed on the anodic electrode were examined using cyclic voltammetry. It was found that some kinds of reduction reactions proceeded and a film on the surface of the anode was formed. The film showed different properties, which were dependent on the mixing ratio of the solvents. From our results, we concluded that the best composition ratio of EC:DEC in 1 M LiPF₆/(EC+DEC) system was approximately 4:6 (EC:DEC, volume ratio).     

Revealing the Potential Application of EC-Synthetic Retinoid Analogues in Anticancer Therapy

(1) Background and Aim: All-trans retinoic acid (ATRA) induces differentiation and inhibits growth of many cancer cells. However, resistance develops rapidly prompting the urgent need for new synthetic and potent derivatives. EC19 and EC23 are two synthetic retinoids with potent stem cell neuro-differentiation activity. Here, these compounds were screened for their in vitro antiproliferative and cytotoxic activity using an array of different cancer cell lines. (2) Methods: MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, AV/PI (annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI)), cell cycle analysis, immunocytochemistry, gene expression analysis, Western blotting, measurement of glutamate and total antioxidant concentrations were recruited. (3) Results: HepG2, Caco-2, and MCF-7 were the most sensitive cell lines; HepG2 (ATRA; 36.2, EC19; 42.2 and EC23; 0.74 µM), Caco-2 (ATRA; 58.0, EC19; 10.8 and EC23; 14.7 µM) and MCF-7 (ATRA; 99.0, EC19; 9.4 and EC23; 5.56 µM). Caco-2 cells were selected for further biochemical investigations. Isobologram analysis revealed the combined synergistic effects with 5-fluorouracil with substantial reduction in IC₅₀. All retinoids induced apoptosis but EC19 had higher potency, with significant cell cycle arrest at subG₀-G₁, -S and G₂/M phases, than ATRA and EC23. Moreover, EC19 reduced cellular metastasis in a transwell invasion assay due to overexpression of E-cadherin, retinoic acid-induced 2 (RAI2) and Werner (WRN) genes. (4) Conclusion: The present study suggests that EC-synthetic retinoids, particularly EC19, can be effective, alone or in combinations, for potential anticancer activity to colorectal cancer. Further in vivo studies are recommended to pave the way for clinical applications.     

Estimation of Ethyl Cellulose Layer Thickness of Coated Polyethylene Oxide Particles Using Differential Scanning Calorimetry

Particles of poly(ethylene oxide) (PEO) were coated using ethyl cellulose (EC). Equations and a method were proposed to estimate the EC layer thickness by using differential scanning calorimetry (DSC) based on melting or crystallization heat of phase-change materials. The result shows that EC layer thickness of polyethylene oxide particles determined using DSC is consistent with the result using an optical microscope.     

High Performance Liquid Chromatographic Determination of Phenylenediamines in Aqueous Environmental Samples

Abstract

The use of high performance liquid chromatography (HPLC) for the determination of phenylenediamines has been studied. Detection limits using both ultraviolet (UV) and electrochemical (EC) detectors have been determined and EC is superior in most cases. Chromatographic conditions and sample preparation procedures are described for many phenylenediamines of environmental significance.     

UV-light induced photodegradation of bisphenol a in water: Kinetics and influencing factors

The synthesis of dimethyl carbonate (DMC) from methanol and ethylene carbonate (EC) without using any solvent was investigated in the presence of ionic liquids as catalysts. The conversion of ethylene carbonate was affected by the structure of ionic liquid. For a series of 1-alkyl-3-methylimidazolium ionic liquids, the one with shorter alkyl chain and the one with more nucleophilic anion showed higher reactivity. The conversion of EC also increased with CO₂ pressure and reaction temperature. Esterification of EC and methanol can be considered as a pseudo-first order reaction with respect to EC concentration. The activation energy was estimated as 50.1 kJ/mol.     

Polymer electrolytes based on poly(ester diacrylate), ethylene carbonate, and LiClO4: a relationship of the conductivity and structure of the polymer according to IR spectroscopy and quantum chemical modeling data

New polymer electrolytes based on poly(ester diacrylate) (PEDA), LiClO₄, and additives of ethylene carbonate (EC) have a Li⁺ ion conductivity comparable with that of liquid electrolytes. The conductivity first decreases by an order of magnitude at an EC content of ??5 wt.% and then increases by three orders of magnitude at 55 wt.% EC. To understand the nature of this extreme dependence, a comprehensive study using IR spectroscopy and quantum chemical modeling was performed. It was found that the changes in the IR spectra with an increase in the EC content were stepwise to form at final stage the same absorption peaks that were observed for the IR spectra of LiClO₄ solutions in EC. The density functional theory studies of the energy and structures of mixed Li⁺ complexes and LiClO₄ with EC and PEDA, which was modeled by oligomers H-((CH₂)₂COO(CH₂)₂O) _n -CH₃ (n ?? 10) showed a stronger binding of the lithium ion with the polymer matrix in the mixed complexes with one EC molecule at a low content of EC resulting, most likely, in a decrease in the conductivity. Less stable mixed complexes with three EC molecules can be formed with an increase in the EC fraction and they become unstable in EC excess because of the transition of the Li⁺ ions to solvate complexes containing only EC molecules.     

Solid asymmetric electrochemical capacitors using proton-conducting polymer electrolytes

Solid asymmetric electrochemical capacitors (EC) using polyvinyl alcohol (PVA)–heteropoly acid (HPA) electrolytes and RuO₂–graphite electrodes were developed. The devices were about 0.2 mm thick and had a working voltage window of 0–1.5 V, 50% wider than that of any proton-conducting symmetric EC. Pseudocapacitance from HPA contributes to the total capacitance of the asymmetric EC within a certain potential window. The PVA–HPA polymers have been proven to function both as electrolyte and as pseudocapacitive electrode material in EC cells.     

Fast printing of thin,large area,ITO free electrochromics on flexible barrier foil

Processing of large area, indium tin oxide (ITO) free electrochromic (EC) devices has been carried out using roll‐to‐roll (R2R) processing. By use of very fine high‐conductive silver grids with a hexagonal structure, it is possible to achieve good transparency of the electrode covered substrates and when used in EC devices switching times are similar to corresponding ITO devices. This is obtained without the uneven switching of larger areas, which is generally observed when using ITO because of its high‐sheet resistance. The silver electrode structures for 18 × 18 cm² devices can be processed at high speed (10 m/min) on PET by flexographic printing and the EC polymer ECP‐Magenta as well as a minimal color changing polymer MCCP by slot‐die coating, showing the potential for fast fabrication of large volumes of low‐priced flexible EC devices by use of R2R processing techniques. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Labeled vs. Label-Free Raman Imaging of Lipids in Endothelial Cells of Various Origins

Endothelial cells (EC) constitute a single layer of the lining of blood vessels and play an important role in maintaining cardiovascular homeostasis. Endothelial dysfunction has been recognized as a primary or secondary cause of many diseases and it manifests itself, among others, by increased lipid content or a change in the lipid composition in the EC. Therefore, the analysis of cellular lipids is crucial to understand the mechanisms of disease development. Tumor necrosis factor alpha (TNF-α)-induced inflammation of EC alters the lipid content of cells, which can be detected by Raman spectroscopy. By default, lipid detection is carried out in a label-free manner, and these compounds are recognized based on their spectral profile characteristics. We consider (3S,3′S)-astaxanthin (AXT), a natural dye with a characteristic resonance spectrum, as a new Raman probe for the detection of lipids in the EC of various vascular beds, i.e., the aorta, brain and heart. AXT colocalizes with lipids in cells, enabling imaging of lipid-rich cellular components in a time-dependent manner using laser power 10 times lower than that commonly used to measure biological samples. The results show that AXT can be used to study lipids distribution in EC at various locations, suggesting its use as a universal probe for studying cellular lipids using Raman spectroscopy. The use of labeled Raman imaging of lipids in the EC of various organs could contribute to their easier identification and to a better understanding of the development and progression of various vascular diseases, and it could also potentially improve their diagnosis and treatment.     

Ring‐opening copolymerization of ethylene carbonate and ε‐caprolactone catalyzed by neodymium tris(2,6‐di‐tert‐butyl‐4‐methylphenolate): Synthesis,characterization, and dynamic mechanic analysis

The ring‐opening copolymerization of ethylene carbonate (EC) with ε‐caprolactone (CL) was carried out using neodymium tris(2,6‐di‐tert‐butyl‐4‐methylphenolate) as a single‐component catalyst. Copolymers containing up to 22.0% EC contents with high molecular weights (up to 23.97 × 10⁴) and moderate molecular weight distributions (between 1.66 and 2.03) were synthesized at room temperature. Compared with homopoly(ε‐caprolactone), the copolymers with EC units exhibited increased glass transition temperatures (?35.6 °C), reduced melting temperatures (44.5 °C), and greatly enhanced elongation percentage at break (2383%) based on dynamic mechanic analysis. The crystallinities of the copolymers decreased with the increasing EC molar percentage in the products. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4050–4055, 2008     

Study of metabonomic profiles of human esophageal carcinoma by use of high-resolution magic-angle spinning 1H NMR spectroscopy and multivariate data analysis

Esophageal carcinoma (EC) is one of the most common malignant tumors. EC survival has remained disappointingly low because of the high malignancy of esophageal cancer and the lack of obvious clinical symptoms at an early stage. Early diagnosis is often difficult because the small tumor nodules are frequently missed. Metabonomics based on high-resolution magic-angle spinning (HRMAS) NMR has been popular for tumor detection because it is highly sensitive, provides rich biochemical information and requires no sample pretreatment. ¹H HRMAS spectra of non-involved adjacent esophageal tissues and of well differentiated and moderately differentiated esophageal carcinoma tumors were recorded and analyzed by use of multivariate and statistical analysis techniques. Moderately differentiated EC tumors were found to have increased total choline, alanine, and glutamate and reduced creatine, myo-inositol, and taurine compared with non-involved adjacent tissues. Moreover, clear differences between the metabonomic profiles of EC tissues enabled tumor differentiation. Furthermore, the integral Gly/MI ratio for samples of different tissue types were statistically significantly different; this was sufficient both for distinguishing non-involved tissues from esophageal carcinoma and for classification of well differentiated and moderately differentiated EC tumors.

Self‐association of cellulose ethers with random and regioselective distribution of substitution

2 to 4% aqueous solutions of regioselectively substituted 3‐mono‐O‐ethyl‐ ( 3‐EC ) and randomly substituted ethyl‐ ( EC ) cellulose show association and gelation above 50–60 and 20–30 °C, respectively. In contrast, almost no association or gelation was seen with regioselectively substituted 3‐mono‐O‐methoxyethyl cellulose ( 3‐MEC ). This could be assessed by eye and measured using the techniques of ¹H high‐resolution nuclear magnetic resonance, oscillatory rheology, and micro‐differential scanning calorimetry (DSC). Several processes are thought to occur during association and gelation of EC and 3‐EC . These were separated with respect to temperature, to varying degrees, on cooling and have been modeled using DSC data. In accordance with other work in the literature, they are thought to be, on heating, the disassociation of structures in solution followed first by the formation of water cages and then by the association of hydrophobic moieties into a precipitate or gel. Contrasting with previous work (Haque and Morris, Carbohydr Polym 1993, 22, 161–173), the rheological measurements do not show “two distinct waves of structure formation” at the present concentrations and the DSC measurements show, on cooling, an extremely wide separation in temperature of the processes for the regioselectively substituted cellulose derivative 3‐EC . © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1743–1752, 2009     

Inexpensive isolation of beta-D-glucopyranosidase from alpha-L-arabinofuranosidase,alpha-L-rhamnopyranosidase,and o-acetylesterase

β-d-Glucopyranosidase (βG, EC 3.2.1.21) has been isolated from some collateral activities, α-l-arabinofuranosidase (Ara, EC3.2.1.55), α-l-rhamnopyranosidase (Rha, EC 3.2.1.40), and o-acetylesterase (Est, EC 3.1.1.53), using a commercial enzyme preparation and a simple method economically sustainable for the food industry. The procedure comprises precipitation of extraneous substances by adding ethanol and CaCl₂, ultrafiltration, and adsorption, first on bentonite and then on chitosan. The results obtained were the complete isolation of βG from the above-mentioned activities, a drastic reduction in extraneous compounds, such as brown substances and polysaccharides, and a slight increase in purification.     

The mid-infrared (attenuated total reflection) spectroscopy of ethylene carbonate in water.

Ethylene carbonate (EC) and water solution compositions ranging from pure water to 60 mass% EC have been examined using infrared (attenuated total reflection) spectroscopy. The fundamental vibrational modes of EC in the mid-infrared between 2050 and 1000 cm(-1) were fitted to mixed Lorentzian-Gaussian bandshapes. The spectral data for EC bands between 1000 and 650 cm(-1) are also shown but were not curve-fitted due to baseline distortions from water librational modes. The results of the band analysis have provided information regarding the molecular structure of these solutions, and the fact that the structure is also concentration dependent. The Fermi resonance coupling between the v2 and 2v7 vibrations of EC have been analysed using a standard perturbation model.     

Enzyme-catalyzed synthesis of nucleoside triphosphates from nucleoside monophosphates

Syntheses of adenosine 5′-triphosphate (ATP) from adenosine 5′-monophosphate (AMP) and ribavirin 5′-triphosphate (RTP) from ribavirin 5′-monophosphate (RMP) (1) were performed using enzymes as catalysts. Synthesis of ATP is based on acetyl phosphate as the phosphate donor, and acetate kinase (Bacillus stearothermophilus, EC 2.7.2.1), adenylate kinase (porcine muscle, EC 2.7.4.3), and inorganic pyrophosphatase (yeast, EC 2.6.1.1) as the catalysts. Three reactions on a 150-mmol scale provided ATP as its barium salt in 82% yield and 67% purity. Synthesis of RTP used phosphoenol pyruvate (PEP) as the phosphate donor, and pyruvate kinase (rabbit muscle, EC 2.7.1.40) and adenylate kinase (rabbit muscle) as the catalysts. A gram-scale reaction provided RTP as its barium salt in 93% yield and 97% purity. This work demonstrates the utility of the autoxidationresistant acetate kinase fromB. stearothermophilus, the value of pyrophosphatase in controlling the level of pyrophosphate in the reactions and the ability of adenylate kinase to accept at least one substrate other than a derivative of adenosine.     

Synthesis of dimethyl carbonate (dmc) from co2, ethylene oxide and methanol using heterogeneous anion exchange resins as catalysts

Summary A two-step synthesis of dimethyl carbonate (DMC) from ethylene oxide (EO), carbon dioxide and methanol using heterogeneous anion exchange resins as catalysts is reported. The first step is the reaction of EO with CO₂ to form ethylene carbonate (EC), and the second one the transesterification of EC with methanol to yield DMC. Effect of various reaction parameters on the activity and selectivity of the catalysts used was investigated. After the first step, the crude mixture containing EC was directly reacted with methanol in the presence of a heterogeneous anion exchange resin catalyst to produce DMC in high yield and selectivity. Our process is highly economic.