Pharmacological and Therapeutic Applications of Esculetin

Esculetin is a coumarin compound, which belongs to the class of benzopyrone enriched in various plants such as Sonchus grandifolius, Aesculus turbinata, etc. Free radicals lead to the development of oxidative stress causing inflammation, arthritis, cancer, diabetes, fatty liver disease, etc. These further reduce the efficacy of anticancer drugs, activate inflammatory signaling pathways, degrade joints and cartilage, and disrupt the glycemic index and normal function of liver enzymes. For instance, the current treatment modalities used in arthritis such as non-steroidal anti-inflammatory drugs, disease-modifying anti-rheumatoid drugs, and lipoxygenase inhibitors present limited efficacy and adverse effects. Thus, there is a constant need to find newer and safer alternatives. Esculetin has an immense antioxidative potential thereby alleviating arthritis, diabetes, malignancies, and hepatic disorders. Structurally, esculetin contains two hydroxyl groups, which enhance its ability to function as an antioxidant by inhibiting oxidative stress in pathological conditions. Leukotriene B4 synthesis, NF-κB and MPAK pathway activation, and inflammatory cytokine production are the main causes of bone and joint deterioration in arthritis, whereas esculetin treatment reverses these factors and relieves the disease condition. In contrast, lipid peroxidation caused by upregulation of TGF-β-mediated expression and dysfunction of antioxidant enzymes is inhibited by esculetin therapy, thus reducing liver fibrosis by acting on the PI3K/FoxO1 pathway. Therefore, targeting NF-κB, pro-inflammatory cytokines, TGF-β and oxidative stress may be a therapeutic strategy to alleviate arthritis and liver fibrosis.     

四氯化碳催化加氢研究进展

从四氯化碳选择性加氢脱氯催化剂的活性组分、反应机理和催化剂失活及预处理等方面详细介绍了四氯化碳选择性加氢脱氯反应及催化剂的最新研究进展,简述了反应温度、压力和n(H2)/n(CCl4)比对四氯化碳催化加氢产品分布的影响,并指出了四氯化碳选择性加氢脱氯反应的发展方向。     

CCl4加氢脱氯合成CHCl3的研究进展

CCl₄加氢脱氯合成CHCl₃是一条具有工业前景的新型合成路线。论述了Pt/Al₂O₃催化剂Pt粒径、前驱体、反应压力、n(H₂)∶n(CCl₄)和惰性气体等因素对气相催化CCl₄加氢脱氯反应的影响。     

我国四氯化碳现状和出路

通过对国内四氯化碳产能、产量、原料路线、用途和用量等现状的分析，提出了四氯化碳的出路，同时介绍了焚烧技术和以四氯化碳为原料特产氯仿、四氯乙烯、一氯甲烷、HFC—236af、肉桂酸等产品的最新进展。     

Kinetic study of the reaction between molybdenum trioxide and gaseous carbon tetrachloride

The kinetics of the chlorination reaction of molybdenum trioxide with gaseous carbon tetrachloride has been studied at temperatures between 713 and 753 K. The effects of temperature, reaction time, residence time and gaseous reactant concentration on conversion were studied throughout the reaction. In all cases, there was an increase in conversion when the above operating variables were increased. The kinetic model proposed is consistent with and correlates the experimental data. In the range studied for the different variables, the step that controls the rate of reaction is the surface chemical reaction. Values of the rate constant and the activation energy were estimated.     

四氯化碳生产中氯化反应的回火原因分析与对策

探讨了四氯化碳生产中氯化反应的回火原因及避免回火的对策 ,解决了生产中的实际问题     

CCl4低温氯化人造金红石制备TiCl4

为了开发低温钛氯化工艺及解决工业副产物CCl₄的再利用问题,在固定床和流化床反应器中考察了自贡法人造金红石原料与CCl₄低温氯化制备TiCl₄的反应过程,利用SEM、XRD、XPS等手段表征了人造金红石原料在反应前后的变化。结果显示,在450～500℃下,自贡法人造金红石能与CCl₄快速反应生成TiCl₄产品。少量Fe元素的掺杂是金红石相具备较高反应速率的关键原因。人造金红石原料制备过程中的弱氧化焙烧处理在颗粒表面形成的惰性金红石壳层,导致TiCl₄收率极限为90%,但该壳层能在酸解过程以及低温CCl₄氯化过程中维持颗粒粒度,使该原料能用于流化床操作。此过程具有显著的环保价值和工业应用前景。     

药物合成反应中四氯化碳的应用及替换研究进展

综述了四氯化碳在药物合成反应中的应用,总结了在药物合成反应中四氯化碳溶剂替换研究工作.     

固体氯蜡－70中四氯化碳含量的测定

提出了采用气相色谱顶空取样的方法测定氯化石蜡-70中残余四氯化碳的含量,其加样平均回收率为99.34％,该方法操作简便,测量快速、准确,对于提高氯蜡-70的产品质量,具有一定的指导意义。     

苯乙烯-四氯化碳合成肉桂酸工业化问题的探讨

传统的肉桂酸制备方法——帕金反应法 ,因反应温度高、能耗多、产率低等缺点而削弱了竞争力。新方案改革了工艺 ,剔除了加成液的水洗、酸洗、干燥工序 ,直接回收四氯化碳 ,中间体直接进入水解 ,回收醋酸后再经一系列处理 ,能一次性地得到合格产品     

Electrochemical behaviour of uranium (IV) in DMF at vitreous carbon

The electrochemical behaviour of UCl₄ (0.01 mol L⁻¹ up to 0.05 mol L⁻¹) in 0.1 mol L⁻¹ TBAPF₆/DMF solution at vitreous carbon was studied, at room temperature, by cyclic voltammetry and potentiostatic techniques. The electrolytic solutions were analyzed by UV spectroscopy (UV), and the electrodeposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and X-ray diffraction (XRD). The cyclic voltammetric results, at low UCl₄ concentrations (0.01 mol L⁻¹), point that the reduction of U(IV) to U(0) occurs in two steps involving mainly U(IV) and U(III) species. The first electron transfer reaction is quasi-reversible and the second irreversible. The diffusion coefficient of U(IV) in DMF and the charge rate constant were determined to be 4.78 × 10⁻⁷ cm² s⁻¹ and 1.93 × 10⁻³ cm s⁻¹ (at 0.02 V s⁻¹), respectively.RBS data obtained from samples prepared at constant potential (−3.10 V) during 3 h at room temperature, indicated the presence of uranium particles deposited all over the vitreous carbon surface with aggregates in some places, confirming that the second reduction step corresponds to uranium electrodeposition. No crystallographic ordering could be seen by XRD, pointing to an amorphous character of the uranium films.     

二硫化碳-四氯化碳精馏过程模拟与优化

为实现二硫化碳氯化工艺中产生的二硫化碳和四氯化碳的完全回收,利用Aspen Plus软件对二硫化碳、四氯化碳混合物的精馏工艺进行了模拟计算.分析了理论塔板数、进料口位置、回流比对分离效果的影响,选出最适宜的工艺条件:理论塔板数为21块,进料口位于第9块塔板,回流比为1.9.在该工艺条件下,塔顶温度为46.9℃,二硫化碳...     

Feasibility study for reductive destruction of carbon tetrachloride using bare and polymer coated nickel electrodes

This research investigated the feasibility of an electrochemical reductive dechlorination method for removing carbon tetrachloride (CT) from contaminated waters. Reaction rates and Faradaic current efficiencies were measured for CT dechlorination in small flow-through reactors utilizing bare and silicone polymer coated nickel cathodes. CT dechlorination resulted in near stoichiometric production of methane. Rates of CT reduction were found to follow a first-order kinetic model for all CT concentrations investigated. CT disappearance was limited by its reaction rate, and the performance of the reactor could be approximated with an ideal plug-flow reactor model. Destruction half-life values for CT with the bare nickel electrode ranged from 3.5 to 5.8min for electrode potentials ranging from –652 to –852mV with respect to the standard hydrogen electrode (SHE). The apparent electron transfer coefficient for CT reduction was only 0.06. The low transfer coefficient can be attributed to oxides coating the electrode surface that contributed to mass transfer resistance for CT reduction. Faradaic current efficiencies for CT reduction were found to decline with decreasing electrode potential. This can be attributed to an electron transfer coefficient for water reduction of 0.33 that was significantly greater than that for CT reduction. Faradaic current efficiencies could be increased by 100–360% by coating the electrode with a silicone polymer. In addition to decreasing the rate of water reduction by acting as hydrophobic mass transfer barrier, the polymer coating resulted in small increases in CT reaction rates. The energy cost per volume of water treated was strongly dependent on the electrode potential, but only weakly dependent on the influent CT concentration over the range of practical interest. The energy costs for reductive dechlorination appear to be lower than the carbon costs for adsorptive treatment of CT. This indicates that low current efficiencies at low CT concentrations are not a significant obstacle for developing a practical treatment process. The main impediment to electrochemical treatment for removing CT from water is the slow reaction rate that requires large reactors for obtaining sufficient hydraulic detention time to meet effluent water standards.     

气相色谱法监测氯磺化聚乙烯生产过程中四氯化碳含量

提出了将生产氯磺化聚乙烯中各控制点的不同状态的样品(液体、固体)处理成易于气相色谱分析的样品的方法。为了提高分析准确度。采用不同的定量方法监测其中的四氯化碳含量。该方法在实际应用中取得了满意的结果。     

四氯化碳液相催化加氢制氯仿反应动力学研究

使用高压搅拌釜,在123℃实验条件下,对四氯化碳、二氯甲烷、三氯甲烷、催化剂组成的反应体系进行动力学研究,用最小二乘法对数据进行回归处理,并建立反应动力学方程。     

Formation of chlorine species over magnesium oxide in the oxidative coupling of methane in the presence of carbon tetrachloride

The oxidative coupling of methane on magnesium oxide (MgO) has been studied in the presence of carbon tetrachloride (TCM) as a gas-phase additive. Addition of a small amount of TCM to the reactant stream improves the selectivity to C₂H₄, while the conversion of methane is not influenced by the additive. X-ray photoelectron spectra of the used MgO reveal the formation of chlorine species on the catalyst surface in quantities up to 0.20 of Cl/Mg (atomic ratio), although X-ray diffraction spectra of the catalyst show MgO only and the content of the chlorine species in the bulk phase estimated by X-ray fluorescence analysis is very low. It is concluded that the enhancement of the selectivity to C₂H₄ primarily results from the presence of surface chlorine species. The chlorinated species on the catalyst has been identified as MgCl₂.     

Union production of low chlorinated polyethylene and chlorinated paraffin via a carbon tetrachloride solvent free process

A novel process for producing low chlorinated polyethylene (LCPE) with chlorinity of 28–33% by weight is presented, in which a reactive solvent, paraffin, is used as a green solvent to replace the commonly used inert solvent, carbon tetrachloride (CTC), an ozone depleting substance (ODS) being phased out under the Montreal Protocol. This process utilizes the principle that paraffin can dissolve high density polyethylene (HDPE) at about 135°C and the resulting solution can be chlorinated by chlorine forming two useful products simultaneously, viz chlorinated paraffin (CP) and LCPE, which are mutual soluble even at lower temperature e.g.70°C. The present process is superior to the conventional CTC solvent method because it can reduce the solvent emission dramatically, enhance the volume efficiency of reactor and achieve a union production of LCPE and CP under atmospheric pressure. The structure and properties of LCPE produced by two different methods are determined by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectrometer, proton magnetic resonance (¹H NMR), and gel permeation chromatography (GPC). The results indicate that polyethylene chain can be homogeneously chlorinated in paraffin as in CTC solvent via a radical mechanism, and the chlorinity of CP and LCPE is virtually same under optimal conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

乙酸乙酯/四氯化碳二元混合体系的体积性质

常压下测定了乙酸乙酯与四氯化碳二元体系在288.15-323.15 K内全摩尔分数范围的密度,分别建立了该二元体系密度与组成和温度的计算方程.在此基础上,计算了该二元体系的超额摩尔体积,结果表明:该二元体系的超额摩尔体积在所测定温度和全摩尔分数范围内均呈正偏差,且均随温度的升高而偏差增大,并利用Redlich-Kist...     

Atomistic molecular dynamics simulation of liquid carbon tetrachloride confined in pillared pore materials

Atomistic molecular dynamics simulations were performed to investigate the dependence of the self-diffusivity of liquid carbon tetrachloride (CCl₄) confined in pillared pore materials on the pore width, porosity and the surface heterogeneity of the solid walls. The simulated results show that the self-diffusivity of liquid CCl₄ does not increase monotonically with the pore width, but in an oscillatory manner to approach the bulk diffusivity. Moreover, the presence of activated sites characterizing the surface heterogeneity and the pillars reduces the self-diffusivity of liquid CCl₄ confined in pillared pores. The effects of these factors on the self-diffusivity of fluids should be taken into account when a porous nanomaterial is designed or chosen for a certain process, in addition to their effects on other properties such as the adsorption capability.     

RIPK1 in Liver Parenchymal Cells Limits Murine Hepatitis during Acute CCl4-Induced Liver Injury

Some life-threatening acute hepatitis originates from drug-induced liver injury (DILI). Carbon tetrachloride (CCl₄)-induced acute liver injury in mice is the widely used model of choice to study acute DILI, which pathogenesis involves a complex interplay of oxidative stress, necrosis, and apoptosis. Since the receptor interacting protein kinase-1 (RIPK1) is able to direct cell fate towards survival or death, it may potentially affect the pathological process of xenobiotic-induced liver damage. Two different mouse lines, either deficient for Ripk1 specifically in liver parenchymal cells (Ripk1^LPC-KO) or for the kinase activity of RIPK1 (Ripk1^K45A, kinase dead), plus their respective wild-type littermates (Ripk1^fl/fl, Ripk1^wt/wt), were exposed to single toxic doses of CCl₄. This exposure led in similar injury in Ripk1^K45A mice and their littermate controls. However, Ripk1^LPC-KO mice developed more severe symptoms with massive hepatocyte apoptosis as compared to their littermate controls. A pretreatment with a TNF-α receptor decoy exacerbated liver apoptosis in both Ripk1^fl/fl and Ripk1^LPC-KO mice. Besides, a FasL antagonist promoted hepatocyte apoptosis in Ripk1^fl/fl mice but reduced it in Ripk1^LPC-KO mice. Thus, the scaffolding properties of RIPK1 protect hepatocytes from apoptosis during CCl₄ intoxication. TNF-α and FasL emerged as factors promoting hepatocyte survival. These protective effects appeared to be independent of RIPK1, at least in part, for TNF-α, but dependent on RIPK1 for FasL. These new data complete the deciphering of the molecular mechanisms involved in DILI in the context of research on their prevention or cure.