Variations of Antioxidant Properties and NO Scavenging Abilities during Fermentation of Tea

Tea is known as one of the most popular beverages in the world, which is believed to be beneficial for health. The main components in tea will change a lot depending on the different processes of fermentation, and thus the effects of different teas on human health may differ. The aim of this study is to explore the varied abilities of reactive oxygen species (ROS) and nitric oxide (NO) scavenging during the fermentation of tea. In this study, we conducted the in vitro experiments which involved some reaction systems indicating the abilities of scavenging ROS and NO. We also investigated the effects of tea and their components (catechins, theabrownins, caffeine) on the intracellular levels of ROS and NO, using Raw 264.7 cells as the model. We found that regardless of whether it was out of cell system or in Raw 264.7 cells, the abilities of scavenging ROS would decrease during the fermentation of tea. Further, the post-fermented pu-erh tea showed the best effect on inhibiting the lipopolysaccharide (LPS)-induced production of NO. These findings indicated that the fermentation process caused a change of the components which might be due to the changes of their antioxidant properties and NO scavenging abilities.     

丙二酰氧基硼氢化钠介入的醛、酮还原胺化反应

叙述了在原位生成的丙二酰氧基硼氢化钠存在下的醛、酮还原胺化反应。讨论了还原胺化的反应条件和立体位阻效应,发现丙二酰氧基硼氢化钠是一个高选择性还原剂,在给定条件下不发生自身还原反应。     

Free Radical Scavenging and Cellular Antioxidant Properties of Astaxanthin

Astaxanthin is a coloring agent which is used as a feed additive in aquaculture nutrition. Recently, potential health benefits of astaxanthin have been discussed which may be partly related to its free radical scavenging and antioxidant properties. Our electron spin resonance (ESR) and spin trapping data suggest that synthetic astaxanthin is a potent free radical scavenger in terms of diphenylpicryl-hydrazyl (DPPH) and galvinoxyl free radicals. Furthermore, astaxanthin dose-dependently quenched singlet oxygen as determined by photon counting. In addition to free radical scavenging and singlet oxygen quenching properties, astaxanthin induced the antioxidant enzyme paroxoanase-1, enhanced glutathione concentrations and prevented lipid peroxidation in cultured hepatocytes. Present results suggest that, beyond its coloring properties, synthetic astaxanthin exhibits free radical scavenging, singlet oxygen quenching, and antioxidant activities which could probably positively affect animal and human health.     

Radical Scavenging Activity and Pharmacokinetic Properties of Coumarin–Hydroxybenzohydrazide Hybrids

Free radicals often interact with vital proteins, violating their structure and inhibiting their activity. In previous studies, synthesis, characterisation, and the antioxidative properties of the five different coumarin derivatives have been investigated. In the tests of potential toxicity, all compounds exhibited low toxicity with significant antioxidative potential at the same time. In this paper, the radical scavenging activity of the abovementioned coumarin derivatives towards ten different radical species was investigated. It was found that all investigated compounds show good radical scavenging ability, with results that are in correlation with the results published in the previous study. Three additional mechanisms of radical scavenging activity were investigated. It was found that all three mechanisms are thermodynamically plausible and in competition. Interestingly, it was found that products of the Double Hydrogen Atom Transfer (DHAT) mechanism, a biradical species in triplet spin state, are in some cases more stable than singlet spin state analogues. This unexpected trend can be explained by spin delocalisation over the hydrazide bridge and phenolic part of the molecule with a low probability of spin pairing. Besides radical-scavenging activity, the pharmacokinetic and drug-likeness of the coumarin hybrids were investigated. It was found that they exhibit good membrane and skin permeability and potential interactions with P-450 enzymes. Furthermore, it was found that investigated compounds satisfy all criteria of the drug-likeness tests, suggesting they possess a good preference for being used as potential drugs.     

噻吩和苯并噻吩在原位氢存在下的还原脱硫

研究了噻吩和苯并噻吩在原位氢和硼化镍存在下的还原脱硫。实验对操作条件进行了优化;研究了可能的反应机理。结果表明,六水合氯化镍与还原剂于质子溶剂中反应的对硫化物脱硫,产生的原位氢脱硫活性较高;还原剂用量为0.64 g时,脱硫率可达99%以上。噻吩和苯并噻吩脱硫主要发生直接氢解反应;少量苯并噻吩脱硫经由加氢途径进行,硫化物主要通过S原子"端连吸附"在硼化镍表面。推测反应机理为,反应中大量原位氢吸附在硼化镍表面并活化;硼化镍中富电子镍介入硫化物分子中C—S键形成加合物,与活性原位氢进一步作用,使C—S和C—C键断裂。     

含铜和镍电镀污泥还原氨浸工艺及反应动力学分析

采用还原氨浸工艺实现电镀污泥中铜、镍的浸出。在20%(质量分数)氨水+0.3 mol/L (NH₄)₂CO₃+0.4 mol/L Na₂SO₃的浸出体系中,当固液比为1∶15,在70℃下浸出3h,铜、镍的浸出率别为95.84%和90.12%。反应动力学分析表明,氨-碳酸铵-亚硫酸钠体系浸出电镀污泥中铜、镍受界面传质和固体膜层扩散共同控制。     

氩气对NTP转化NO/N_2/O_2气氛中NO的影响及发射光谱分析

为研究氩气(Ar)添加剂对低温等离子体(NTP)转化NO过程的影响,建立了NTP转化NO/N2/O2/Ar气氛中NO的试验平台,考察了激励电压峰-峰值(Vp-p)和Ar浓度对NO转化率、NO2、O3浓度及发射光谱的影响,并结合发射光谱诊断法对NTP转化NO的机理进行了分析。研究结果表明,Vp-p较小时,由于潘宁效应,在NO/N2/O2气氛中加入Ar会增加分子的活化几率;另外添加Ar会引起NTP电子密度的增加,从而促进N、O原子的生成,NO转化率随Ar浓度升高而升高;Vp-p较高时,混合气加入Ar后会抑制O3的生成,O3浓度随Ar浓度升高而降低;NO2浓度的变化趋势与O3浓度变化相似。     

Nickel‐Catalyzed Reductive Benzylation of Aldehydes with Benzyl Halides and Pseudohalides

The reductive benzylation of aromatic and aliphatic aldehydes with benzylic halides is reported using a nickel/zinc catalyst system. In addition to benzylic halides, the first report on the addition of benzylic triflates, acetates, tosylates and tritylates to aldehydes is also presented. By this new method a range of alcohols was synthesized efficiently from aldehydes and benzylic substrates at room temperature in moderate to high yields. The mild reaction conditions and good functional group tolerance make this nickel‐catalyzed process synthetically useful for the synthesis of diverse benzylic alcohols.

     

Well defined CuI(NO), CuI(NO)2 and CuII(NO)X (X = O− and/or NO 2 − ) complexes in CuI-ZSMS prepared by interaction of H-ZSM5 with gaseous CuCl

In this note an exchange procedure of the acidic protons of H-ZSM5 by Cu^I ions through reaction with CuCl in the gas phase is described. In the so obtained Cu^I-ZSM5 exchanged zeolite the Cu^I ions are in well defined configuration and form with NO mono and di-nitrosyl complexes of high structural and spectroscopic quality. The Cu^I(NO)₂ species are transformed at RT into Cu^II(NO)X (X=O^– and/or NO ₂ ^– ) species which could represent an intermediate in NO decomposition.     

一些天然提取物对超氧自由基和羟基自由基的清除作用

皮肤衰老与自由基有着密切关系。利用邻苯三酚自氧化产生超氧自由基（Ｏ２）,Ｆｅｎｔｏｎ反应产生羟基自由基（ＯＨ）,以比色法测定了一些天然提取物对这二种自由基的清除作用,结果表明：这些提取物大都具有清除作用,其中以芦丁、槲皮素,黄芪总黄酮较强。     

NO2 inhibits the catalytic reaction of NO and O2 over Pt

The rate equation for the overall reaction of NO and O₂ over Pt/Al₂O₃ was determined to be r=k_f[NO] ^1.05±0.08[O₂]^1.03±0.08[NO₂]^0.92±0.07(1-), with k_f as the forward rate constant, =([NO₂]/K[NO][O₂]^1/2), and K as the equilibrium constant for the overall reaction. An apparent activation energy of 82 kJ mol^–1 ± 9 kJ mol^–1 was observed. The inhibition by the product NO₂ makes it imperative to include the influence of NO₂ concentration in any analysis of the kinetics of this reaction. The reaction mechanism that fits our observed orders consists of the equilibrated dissociation of NO₂ to produce a surface mostly covered by oxygen, thereby inhibiting the equilibrium adsorption of NO, and the non-dissociative adsorption of O₂, which is the proposed rate determining step.     

Separation of Phosphorus and Magnetic Mineral Fines from Siderite Reductive Ore by Applying Magnetic Flocculation

The characteristics of siderite reductive ore and the ultrafine grinding-magnetic flocculation separation (MFS) of this ore were investigated in the present work. The results indicated that the iron phase in the raw ore was predominantly metallic iron with an iron particle size below 30 μm, and the phosphorus compound was apatite. By applying MFS to siderite reductive ore containing 37.14% Fe and 0.52 P, a concentrate assaying 66.37% Fe and 0.19 P with 74.32% recovery was produced. The iron recovery increased by 5.77% compared with the results of the conventional magnetic separation. The high efficiency in phosphorus removal and iron recovery achieved by the MFS process may be attributed to the adequate liberation of iron particles and the increase in magnetic force on the iron mineral fines in the form of flocs in a magnetic field.     

Nickel-Catalyzed Reductive Coupling of Vinyl Triflates and 1,4-Dicyanobenzene to Access Alkenyl Nitriles

We report a vinyl cyanation reaction of vinyl triflates and readily available 1,4-dicyanobenzene through a nickel-catalyzed reductive coupling process. The reaction is operated under mild conditions with remarkable functional-group compatibility. Cyclic vinyl triflates with various ring sizes and substituents at different positions all reacted smoothly. The synthetic utility is demonstrated by the derivatization of pharmaceutical and natural compounds, a scale-up synthesis, and various functional group transformations. Preliminary mechanistic studies demonstrate that vinyl triflates are more reactive than 1,4-dicyanobenzene towards the oxidative addition to nickel catalyst.     

HIPS和PE-LD阴燃特性的研究

采用锥形量热仪研究了金属化合物、还原性物质等添加剂对HIPS及PE-LD阴燃特性的影响,以及炭黑等填料在阴燃中的作用,并且对阴燃机理作了初步探索。结果表明:常用金属氧化物氧化铁、氧化钙、氧化锌以及氯化铜可以提高炭层活性,能够明显促进HIPS及PE-LD阴燃燃烧;氧化铝、氧化镁、氧化钼降低炭层活性减缓阴燃燃烧; 炭黑为阴燃提供燃料促进阴燃燃烧;阴燃燃烧过程是一个氧气扩散过程,减少阴燃前沿的氧气供应,可以起到抑制阴燃的作用。     

Dynamic Reductive Kinetic Resolution of Benzyl Ketones using Alcohol Dehydrogenases and Anion Exchange Resins

Dynamic reductive kinetic resolutions of racemic 3‐arylalkanones have been performed by the proper combination of an alcohol dehydrogenase and a basic anionic resin. The best results were found for the bioreduction with the alcohol dehydrogenase type A from Rhodococcus ruber DSM 44541 overexpressed in Escherichia coli (E. coli/ADH‐A) and the commercially available evo‐1.1.200, while the Amberlite IRA‐440 C and the DOWEX‐MWA‐1 resins allowed efficient in situ racemizations. Reaction conditions were optimized in terms of enzyme source and loading, type and amount of resin, pH, temperature and reaction times, obtaining a series of (R,R)‐substituted propan‐2‐ols with good conversions and both diastereoselectivity and stereoselectivity. As a proof of concept, the subsequent intramolecular cyclization of a selected propan‐2‐ol substrate afforded a valuable isochroman heterocycle without any loss of the optical purity.

     

Liquid-liquid Extraction Methods to Determine Reductive Dechlorination of 2,4,6-trichlorophenol by Zero-valent Metals and Zero-valent Bimetals

Abstract

The reductive dechlorination of 2,4,6-trichlorophenol (2,4,6-TCP) was studied using zero-valent metals (ZVMs) and bimetals. A reliable extraction method was required to distinguish the removal by chemical transformation from the removal by physical adsorption on the ZVMs or bimetal. Three liquid–liquid extraction methods with ethyl acetate were evaluated by conducting mass recovery tests in the ZVM-chlorophenol systems. A typical liquid–liquid extraction showed low recoveries for 2,4,6-TCP and the reaction products while the modified liquid–liquid extraction involving acid addition gave increased recoveries. The Mg system needed an additional modification since the modified extraction method was not working on the Mg and Pd/Mg system. Pd/Fe and Pd/Zn gave the highest reaction rate for 2,4,6-TCP dechlorination, producing less or no chlorinated daughter compounds while the plain metals such as Fe and Zn showed much slower degradation rates for 2,4,6-TCP.     

分解炉中NO生产模拟与优化

针对水泥行业中水泥分解炉产生NO的过程进行了机理性分析,同时推导了描述分解炉中NO生成的机理性模型,并对分解炉中的NO生成进行了全三维模拟研究.模拟结果与现场测试结果进行了比较,验证了模拟的合理性.对分解炉的生料入口位置进行了改造,在不影响生产的前提条件下,对单独分风、分料和同时分风分料时降低分解炉内NO生成的情况进行了模拟优化,分析得到了分料方法是降低分解炉中NO的最有效途径的结论,为降低水泥分解炉中NO排放提供了实用的参考依据.     

The growth of FeOOH microcrystals and chemisorption rate of NO

The adsorption of NO over a period of 1 ms–1 min on α- and γ-FeOOH with different degrees of crystallization has been examined in order to clarify the fast chemisorption phenomenon. The FeOOH crystals were prepared under the conditions of various reaction temperatures and ageing times. The changes in X-ray diffraction patterns, particle size, specific surface area and electrical conductivity were examined. The fast chemisorption rate constant, k_f, for NO was obtained at 30°C from the conductivity change in the initial stage of NO adsorption. The α-FeOOH aged for 2 days and 6 days, the crystallite size of which approximately 100 Å gave the highest k_f and the greatest amount of chemisorption; the high activity is assumed to be caused by a special surface structure accepting NO molecules. The maximum k_f for α-FeOOH was also for a crystallite size of approximately 100 Å. As the change of k_f with crystal growth for γ-FeOOH is similar to that of electrical conductivity, an electronic factor seems to be most important in the fast chemisorption process of NO on γ-FeOOH.     

大叶榕榕树须总黄酮提取及对羟自由基清除作用

为充分利用大叶榕榕树须植物资源,避免资源的浪费,探讨大叶榕榕树须总黄酮的提取、鉴别方法及对羟自由基清除作用。采用超声波乙醇浸提法、超声波石油醚浸提法、超声波水浸提法分别从大叶榕榕树须中提取黄酮类物质,对所提取的黄酮类物质进行验证,并用紫外分光光度法测定含量。测得样品中总黄酮的含量分别为C=0.7240 mg/mL、0.5962 mg/mL、0.4529 mg/mL,回收率分别为101.0%、99.8%、100.9%,其纯度和产率均较高,其中,超声波乙醇浸提法产率最高。该提取液对Fenton体系产生的.OH自由基有很好的清除作用。该方法采用全物理过程,无任何污染,是提取大叶榕榕树须黄酮类物质的有效途径。大叶榕榕树须总黄酮有清除.OH自由基的作用。     

Ene‐Carbonyl Reductive Coupling Mediated by Zinc and Ammonia for the Synthesis of γ‐Hydroxybutyric Acid Derivatives

The reductive coupling of an aryl carbonyl group with an activated alkene to give the corresponding γ‐hydroxybutyric acid (GHBA) derivative was achieved in the presence of zinc and ammonia. A board scope of GHBA derivatives could be synthesized under ambient conditions by this method. A mechanism involving a Zn‐ketyl radical as the key intermediate is proposed.