Presence Of Lithium Carbonate Research Articles

Thermal transformations of graphite and anthracite in the presence of lithium carbonate

The method of differential scanning calorimetry was used to study mixtures of graphite and anthracite with lithium carbonate in an argon atmosphere and in air. It was found that in the temperature range of 100–500°C, a stronger mass loss occurs in argon than in air. This phenomenon is caused by the removal of oxygen compounds with carbon. Competing processes take place in the air – the formation of oxygen compounds with carbon, coal and desorption of oxygen-containing substances. A comparison of thermal effects on the curves of DSC and gravimetry for graphite–lithium carbonate systems in argon, in air is carried out. It was found that up to 700°C in the reaction products, the molar ratio of carbon oxides (IV; II) can be estimated at 10 : 1. Endothermic effects of lithium carbonate melting in an argon atmosphere for mixtures of graphite and anthracite with lithium carbonate were observed at 732°C and 727°C, respectively. In air, the peaks of endothermic effects do not correspond to the heat absorption curves in argon. The most probable explanations of the observed effects are given – the presence of phases of carbonate and lithium oxide; the manifestation of the stretched nature of the pre-transition region of lithium carbonate. By the method of powder X-ray diffractometry, it was found that the burnout of the carbon phase at 500°C in graphite, anthracite does not lead to a significant change in the interplane distances in lithium carbonate.

Thermal Transformations of Graphite and Anthracite in the Presence of Lithium Carbonate

Thermal Transformations of Graphite and Anthracite in the Presence of Lithium Carbonate

The effect of pH on the corrosion protection of aluminum alloys in lithium-carbonate-containing NaCl solutions

The corrosion inhibiting effect of lithium carbonate has been studied over the pH range relevant for atmospheric corrosion conditions at the polymer/metal interface. It is demonstrated that lithium carbonate offers optimum corrosion protection under moderately alkaline conditions attributed to the formation of a protective layer identified as aluminum-lithium layered double hydroxide. It is proposed that an active-to-passive transition occurs in the presence of lithium carbonate under moderately alkaline conditions where anodic dissolution of the aluminum matrix is an important step prior to the formation of the protective layer. After prolonged exposure, the protective layer is uniformly formed on the surface of AA2024-T3 and lithium containing AA2198-T8 covering both the matrix and active intermetallic particles thus hindering further corrosion reactions.

Effect of lithium carbonate on autophagy and proliferative activity of isolated hepatocytes

The hepatocytes were cultivated in the presence of lithium carbonate (LC) for drugs testing or possible source for transplantation in the treatment of hereditary or terminal liver diseases. The LC, as an inducer of autophagy, is a promising drug for maintaining cell homeostasis and has a significant effect on the ultrastructural organization of hepatocyte cells. Within current investigation, new mechanisms of the biological effects of lithium and the ultrastructural analysis of the primary culture of hepatocytes were studied via flow cytofluorometry, light, and electron microscopy methods. Obtained results demonstrate the absence of the toxic effect of 5 mM of LC on the primary hepatocyte culture. In addition, LC does not block the cell cycle at the G0/G1 stage after 24 h of hepatocyte cultivation and promotes the preservation of their viability by 48 h of the experiment. Moreover, LC does not stimulate hepatocyte apoptosis, induces autophagy and the preserves the proliferative activity of hepatocytes.

ChemInform Abstract: Palladium‐Catalyzed Picolinamide‐Directed Acetoxylation of Unactivated γ‐C(sp3)—H Bonds of Alkylamines.

AbstractN‐Alkylpicolinamide substrates (I) are converted into the corresponding γ‐acetoxylated products in the presence of lithium carbonate, which suppresses the competing intramolecular C‐H amination process.

Analysis of the Li KLL Auger Transition on Freshly Exposed Lithium and Lithium Surface Oxide by AES

Lithium scribed in vacuum and a particle of lithium oxide were analysed by AES and lithium metal exposed to atmosphere for <1 min was analysed by XPS. The oxide particle embedded in the host metal was analysed at low and high take off angles. AES spectra acquired demonstrate the change in the KLL structure with increasing oxygen concentration. Survey spectra as well as high resolution narrow spectra were acquired and are presented. The presence of lithium carbonate, together with the oxide, formed in air, was confirmed by XPS as it is not easily resolvable using AES.

Photochemical Monoalkylation of Propanedinitrile by Electron-Rich Alkenes

The synthesis of monoalkylated propanedinitriles was achieved upon photoirradiation of MeCN/H(2)O solutions containing propanedinitrile (1; malononitrile) and electron-rich alkenes in the presence of lithium carbonate and a catalytic amount of 9-cyanophenanthrene or redox-type photosensitizers (electron-mediating photosensitizers), through regioselective anti-Markovnikov photochemical polar addition of 1 into electron-rich alkenes. With 2,5-dimethyl-2,4-hexadiene (2g) as an electron-rich alkene, propanedinitrile-incorporated dimer 4g was obtained.

Ageing of V 2O 5 thin films induced by Li intercalation multi-cycling

Cyclic voltammetry, XPS, RBS and AFM have been combined to study the ageing mechanism of Li intercalation in V 2O 5 thin films prepared by thermal oxidation of vanadium metal. Multi-cycling tests were performed in 1 M LiClO 4-PC in the potential range E ∈ [3.8, 2.8 V] versus Li/Li +, corresponding to the α-to-δ phase transition. XPS and AFM were performed using direct anaerobic and anhydrous transfer. Capacity fading remains inferior to 20% during ∼2500 cycles. XPS shows slight modifications of the oxide composition with a V 4+ concentration increasing from ∼5% prior to cycling to ∼16–27% after cycling, due to Li trapped in the oxide film and to the loss of V 2O 5 active material. The presence of lithium carbonate and lithium-alkyl carbonate species evidences the formation of the so-called SEI layer. AFM evidences the loss of crystalline material by grain exfoliation from the outer V 2O 5 layer of the oxide film. By further exfoliation, the inner VO 2 layer of the oxide film is reached and pits are formed, occupying ∼9–13% of the surface. This de-cohesion at grain boundaries is attributed to the strain generated by repeated lattice distortions. After 3300 cycles, the disappearance of lithium carbonates, whereas Li-alkyl carbonates and/or Li-alkoxides remain on the surface, indicates the dissolution and/or conversion of the SEI layer. After 4500 cycles, the oxide film became very labile and could be stripped away by rinsing to reveal the vanadium metal substrate.

Fluorinated, crosslinkable terpolymers based on vinylidene fluoride and bearing sulfonic acid side groups for fuel‐cell membranes

AbstractThe radical terpolymerization of 8‐bromo‐1H,1H,2H‐perfluorooct‐1‐ene with vinylidene fluoride (VDF) and perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride is presented. Changing the feed compositions of these three fluorinated comonomers enabled us to obtain different random‐type poly[vinylidene fluoride‐ter‐perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride‐ter‐8‐bromo‐1H,1H,2H‐perfluorooct‐1‐ene] terpolymers containing various sulfonyl fluoride and brominated side groups. Yields higher than 70% were reached in all cases. The hydrolysis of the sulfonyl fluoride group into the SO3Li function in the presence of lithium carbonate was quantitatively achieved without the content of VDF being affected, and so dehydrofluorination of the VDF base unit was avoided. These original terpolymers were then crosslinked via dangling bromine atoms in the presence of a peroxide/triallyl isocyanurate system, which produced films insoluble in organic solvents such as acetone and dimethylformamide (which totally dissolved uncured terpolymers). The acidification of SO3Li into the SO3H function enabled protonic membranes to be obtained. The thermal stabilities of the crosslinked materials were higher than those of the uncured terpolymers, and their electrochemical performances were investigated. According to the contents of the sulfonic acid side functions, the ion‐exchange capacities ranged from 0.6 to 1.5 mequiv of H+/g, whereas the water uptake and conductivities ranged from 5–26% (±11%) and from 0.5 to 6.0 mS/cm, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4566–4578, 2006

Selecting Different Complexes from a Dynamic Combinatorial Library of Coordination Compounds

A choice selection: A dynamic combinatorial library of oligonuclear coordination compounds is formed from a flexible tris(catechol) ligand with titanium(IV) ions in the presence of lithium carbonate or potassium carbonate. A trinuclear complex (1) can be isolated by crystallization from DMF. In contrast, well-defined mononuclear (2) compounds are obtained by addition of Na+ as a template, and tetranuclear compounds (3) are isolated by changing the solvent to DMSO.

Synthesis and Electrode Properties of Metastable Li2Mn4 O 9 − δ Spinel Oxides

spinel oxides with 0.36 < δ < 0.46 were synthesized by oxidation of aqueous with hydrogen peroxide or lithium peroxide in the presence of lithium carbonate or lithium hydroxide followed by firing the precursor in air at 300–400°C spinel is metastable and disproportionates at about 500°C to give a lithium‐rich spinel and . The disproportionation temperature and the amount of impurity formed depended on the synthesis procedure and raw materials used. Use of lithium peroxide and lithium hydroxide in the solution‐based oxidation procedure produced the least amount of impurity at intermediate temperatures. However, the value of x in the lithium‐rich spinel decreased with a further increase in firing temperature, and the stoichiometric spinel without impurity was formed at 800°C. Phase analysis as a function of firing temperature for a wider range of Li/Mn ratios in the system (0.7 ≤ y ≤1.33) also revealed that single‐phase spinel could be formed for the entire firing temperature range 300 ≤ T ≤ 800°C only for a narrow value of 1.05 ≤ y ≤ 1.25. The lithium‐intercalation properties of the metastable spinel were influenced by the firing temperaturfe deltae. A sample formed at an optimum temperature of 400°C showed a capacity of 130 mAh/g in the range 3.8–2.0 V with excellent cyclability. © 2000 The Electrochemical Society. All rights reserved.

Synthesis of (24R)-3β-chloro-7α-bromo-5-hydroxy-5α-stigmastan-6-one and study of its dehydrohalogenation products

Starting from β-cytosterol (1) and going through the intermediate 3β-chloro-5α-hydroxy-6-ketone (2), the 3β-chloro-7α-bromo-5α-hydroxy-6-ketone (3) is synthesized. Dehydrohalogenation of3 in DMF in the presence of lithium carbonate and bromide gives the 6-ketosteroids4–6, depending on the reaction conditions.

Sintering of calcium carbonate in the presence of lithium carbonate additive

It is shown that calcium carbonate can be sintered in the liquid phase at a low temperature (620–650°C). The sintering temperature is decreased by introducing lithium carbonate. It is established that the degree of crushing of the calcium carbonate for sintering is an important factor.

Effect of a Combination of Drawing and Heat Treatment on the Tensile Properties of Poly[1,3,4-oxadiazole-2,5-diyl- 1,4-phenyleneimino(chloroterephthaloyl)imino-1,4-phenylene] Film

Abstract Poly[1,3,4-oxadiazole-2,5-diyl-1,4-phenyleneimino(chloroterephthaloyl)imino-1,4-phenylene] (PBO-ClT) was prepared by the low-temperature solution polycondensation of 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole with 2-chloroterephthaloyl dichloride in the presence of lithium carbonate as an acid accepter in 1-methyl-2-pyrrolidinone (NMP). The value of the inherent viscosity of PBO-ClT was 1.79 dl g−1 in sulfuric acid (0.5 g/100 ml, 25 °C). PBO-ClT was easily dissolved in NMP and N,N-dimethylacetamide (DMA). The solubility of PBO-ClT, chloro-substituted polymer, was larger than that of poly(1,3,4-oxadiazole-2,5-diyl-1,4-phenyleneiminoterephthaloylimino-1,4-phenylene) in these organic solvents. In order to enhance the tensile properties of PBO-ClT films cast from NMP solutions, the films were drawn and heat-treated under various conditions. The films were drawn in a DMA/water mixture (80 : 20, v/v, 70 °C) and subsequently heat-treated (the temperature was raised from room temp to 300 °C at a heating rate of 12—15 °C min−1). The values of the tensile strength, tensile modulus, and breaking energy of the drawn and heat-treated films were 1.30 GPa, 22.8 GPa, and 37.3 MJ m−3, respectively. These values were changed into 1.02 GPa, 18.5 GPa, and 26.9 MJ m−3 after 2 h of heat-aging at 350 °C in air. These results showed the high-temperature durability of the drawn and heat-treated materials.

Thermal decomposition of iron(II) sulphate heptahydrate in the presence of alkali metal carbonates

The thermal decomposition of iron(II) sulphate heptahydrate was carried out in air under dynamic conditions in the presence of lithium, sodium, potassium and rubidium carbonates. The decomposition path in the presence of lithium carbonate differs from that in the presence of the other carbonates. In the presence of lithium carbonate, the heptahydrate loses all the water molecules before entering into reaction with the carbonate. The anhydrous sulphate then reacts with the carbonate, presumably to form iron(II) carbonate, which in turn undergoes decomposition — oxidation via magnetic oxide to ferric oxide. In the case of the other carbonates, iron(II) sulphate enters into reaction with the carbonate in question even before dehydration is complete, to form ferrous carbonate, which in turn reacts with the moisture still present to form green iron(II) hydroxide. This compound then undergoes decomposition — oxidation reactions via magnetic oxide to ferric oxide.

The radiolysis of lithium oxalate induced by the reaction 6Li(n,α) 3H—II : Study by Nondestructive methods

The radiolysis of lithium oxalate induced by alpha- and 3H-particles had been studied by I.R. spectroscopy and thermal analysis. The presence of lithium carbonate in irradiated samples has been directly proved by X-ray and I.R. spectral analysis. The material balance in the overall radiolytic process Li 2( COO) 2 ⇝ Li 2 CO 3+ CO has been attained within 100±7 percent using for lithium oxalate and lithium carbonate determinations I.R. spectral measurements, and for the CO release the weight loss by thermogravimetric analysis. Some preliminary E.S.R. and diffuse reflectance spectroscopic studies have been performed.