Separation of peroxidation products of diacyl-phosphatidylcholines by reversed-phase liquid chromatography-mass spectrometry

Lipid peroxidation process has attracted much attention due to the growing evidence of its involvement in the pathogenesis of age-related diseases. The monitoring of the lipid peroxidation products in phospholipids, formed under oxidative stress conditions, may provide new markers for oxidative stress signaling and for disease states, giving new insights in the pathogenesis process. Reversed-phase liquid chromatographic method coupled to mass spectrometry was developed for the separation of oxidized glycero-phosphatidylcholine (GPC) peroxidation products formed by the Fenton reaction that mimic in vivo oxidative stress conditions. The LC-MS conditions were applied for the separation of peroxidation products of oleoyl- (POPC), lineloyl- (PLPC) and arachidonoyl-palmitoyl phosphatidylcholine (PAPC). The peroxidation products separated included products resulting from the insertion of oxygen atoms in the sn-2 chain (long-chain), and products with the sn-2 chain shortened resulting from cleavage of oxygen-centered radicals (short-chain). Among long-chain products were the keto, hydroxy, hydroperoxide and poly-hydroxy derivatives, while short-chain products included dicarboxylic acids, aldehydes and hydroxy-aldehydes. Separation of long-chain products formed in each phosphatidylcholine was observed, and the reconstructed ion chromatogram of each ion showed an increase in the number of peaks with the increase in the number of oxygen atoms inserted into the phospholipid. Separation of short-chain products took place according to the functional group present at the sn-2 moiety that allowed the elution of dicarboxylic acids distinct from aldehydes. Separation between isomeric structures that were present in short- and long-chain products was also achieved.     

The Research of Sulfuric Acidic Recycling of Aluminum Industry Fluorine-containing Waste Products

The article presents the method of recycling aluminum industry fluorine-containing waste products to produce hydrogen fluoride. We carried out the estimate of the thermodynamic parameters of sulfuric acidic recycling of fluorine-containing waste products. We considered the necessity of waste products preliminary oxidizing roast stage to reduce carbonic constituent due to the interaction between carbonic constituent blocks of the sulfuric acid and waste products. We also carried out the researches for kinetic characteristics and to determine the optimal conditions for the to recycle sulfuric acidic in the fluorine-containing waste products.     

Products of non-flaming combustion of phenol-formaldehyde resin foam

Phenol-formaldehyde foam was decomposed by non-flaming combustion under temperature and atmosphere conditions simulating the main stages of a fire development and the decomposition products were studied. The type and amounts of the products were affected by the decomposition conditions. The residue yield, which was large, decreased with increase in temperature and atmospheric oxygen. Volatile products consisted mostly of light gases with some volatile-condensable products. The volatile products included light hydrocarbons, formaldehyde, phenols, aldehydes, ketones, ethers, oxygen-containing heterocycles, fused ring compounds and benzene and its homologues. The concentration dependence on combustion conditions was studied.     

基于毛细管电泳的环介导恒温扩增技术检测方法研究

以大肠杆菌(E.coli)为对象,采用环介导恒温扩增技术(LAMP)对其扩增,在实验室自制的毛细管电泳-诱导荧光平台上建立了LAMP产物的检测新方法。引物F3,B3,FIP,BIP扩增的E.coli LAMP产物大小为240 bp。优化的毛细管电泳条件为:毛细管有效长度/总长度(10 cm/15 cm),筛分介质溶液为0.5%羟乙基纤维素(1 300 K),电场强度(100 V/cm),进样条件(100 V/cm,1.0 s)。毛细管电泳时,DNA长度在100~500 bp范围内与其迁移时间呈线性关系,相关系数为0.996。在相同毛细管电泳条件下对E.coli LAMP产物进行分析,并利用这种线性关系在电泳图中对E.coli LAMP产物与假阳性产物做区分,结果表明,毛细管电泳技术不仅可在15 min内实现LAMP产物及附加产物的快速检测,而且可快速区分LAMP阳性及假阳性实验产物。采用建立的毛细管电泳快速检测LAMP产物的方法,对AB0174 E.coli基因实施了LAMP,结果表明该方法适合DNA LAMP产物的快速检测。     

Mechanistic pathways of the hydroxyl radical reactions of quinoline. 1. Identification, distribution, and yields of hydroxylated products

The mechanistic details of the hydroxyl radical-induced transformations of quinoline have been elucidated. The nature and distribution of the final products have provided insight into the preferential attack of the hydroxyl radicals at different sites on the aromatic rings. Hydroxylated products at all of the carbon atoms but one, C2, have been observed and quantified following controlled radiolysis of N2O-purged aqueous quinoline solutions. The difference in the growth pattern and the lifetime of the monohydroxylated products under radiolytic conditions, as well as the formation of high-molecular-weight products (e.g., quinoline dimers), shows the complexity of the OH reaction pathways. The radiolytic yields (G values) for the degradation of the quinoline and the formation of the hydroxylated products are calculated in the absence and in the presence of an oxidant, K3Fe(CN)6. The addition of K3Fe(CN)6 changes only the distribution of the hydroxylated products. These experiments indicate that the nature of the hydroxylated products is determined in the initial addition step of the reaction of the hydroxyl radical with quinoline, whereas the chemistry of the OH adducts is relevant to the distribution of the final products. The discrepancy between the products of -radiolysis and the photo-Fenton reaction of quinoline is also discussed.     

芳香类化合物异戊烯基化的研究进展

结构多样的芳香类化合物一直被用作新药发现的线索或主要来源。通过对类药物天然产物进行异戊烯基化结构修饰,能有效提高芳香类化合物生物活性及生物利用度,为新药研究与开发提供简便高效的方法。本文综述了近年来芳香类化合物异戊烯基化的各种方法,以为今后研究提供参考。     

Promising Antimicrobial Properties of Bioactive Compounds from Different Honeybee Products

Bee products have been known for centuries for their versatile healing properties. In recent decades they have become the subject of documented scientific research. This review aims to present and compare the impact of bee products and their components as antimicrobial agents. Honey, propolis, royal jelly and bee venom are bee products that have antibacterial properties. Sensitivity of bacteria to these products varies considerably between products and varieties of the same product depending on their origin. According to the type of bee product, different degrees of activity were observed against Gram-positive and Gram-negative bacteria, yeasts, molds and dermatophytes, as well as biofilm-forming microorganisms. Pseudomonas aeruginosa turned out to be the most resistant to bee products. An analysis of average minimum inhibitory concentration values for bee products showed that bee venom has the strongest bacterial effectiveness, while royal jelly showed the weakest antibacterial activity. The most challenging problems associated with using bee products for medical purposes are dosage and safety. The complexity and variability in composition of these products raise the need for their standardization before safe and predictable clinical uses can be achieved.     

Pyrolysis studies of aromatic polyesters

The products of pyrolysis, at 400°C in vacuo (1 Pa), of poly(ethyleneterephthalate) (PET) and poly(butyleneterephthalate) (PBT) were studied. The products were identified by gas chromatography/mass spectrometry technique. The highly volatile products of PET contained acetaldehyde, benzene, toluene, styrene and ethylbenzene and in the case of PBT, butadiene, tetrahydrofuran, vinylcyclohexene and ethylbenzene were the major products. A qualitative analysis of the products of low volatility revealed that the main components were benzoic acid, terephthalic acid, monovinyl esters of terephthalic acid and higher oligomers in the case of PET, whereas benzoic acid, monobutenyl esters of terephthalic acid and higher oligomers were the main products from PBT. The results obtained were in good agreement with those obtained from pyrolysis experiments, carried out directly in the mass spectrometer. Mechanisms to explain the occurrence of the different products are proposed.     

Influence of photo-Fries reaction products on the photodegradation of bisphenol-A polycarbonate

The photodegradation of BPA polycarbonate (PC) can be described as an autoaccelerating process initiated by the formation of biphenol products arising from a formal photo-Fries reaction pathway. Evidence comes from spiking PC films with model compounds of photo-Fries reaction products, pre-exposure of films to generate photo-Fries products, and kinetic analysis. Published data on products formed during natural PC weathering are consistent with this pathway.     

Microbial‐induced synthesis of mineralization products based on the capture of carbon dioxide: Characteristics,reaction kinetics,interfacial adhesion properties,and mechanism of action

As a new type of green environment‐friendly cementitious material, microbial‐induced mineralization products have garnered more and more attention. In this paper, the synthesis of mineralization products under microbial inducement was conducted. The composition and microstructure of mineralization products were studied using energy‐dispersive spectrometer (EDS), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The results showed that mineralization products were calcite, while the shape was similar to globular type, and particle size was about 5 μm. The effect of microbial culture solution, secretion solution, and concentration on the conductivity of the solution was compared and analyzed. During the formation of mineralization products, bacterial bodies not only played the role of nucleation sites but also accelerated the deposition of mineralization products. Thus, it could be seen that the bacterial bodies had a certain influence on the reaction kinetics. The adhesion force of mineralization products was evaluated by the interfacial adhesion properties between the mineralization products and glass slides. The results of the sonication test and scratch test indicated that the interfacial adhesion strength between mineralization products and glass slides was closely related to the mass of mineralization products deposited. The larger the mass of mineralization products deposited, the greater the interfacial adhesion strength. Based on the above research and analysis, the reaction process and mechanism model of microbial‐induced mineralization were defined.     

Identification of the decomposition products of nitrobenzanthracenes in solution

Air oxidation products of nitrobenzanthracenes and nitrodibenzanthracenes were separated with high-performance liquid chromatography. The major products were identified as quinones, and the bulk fo the minor products were identified as nitroquinones. Tentative structures are assigned on the basis of mass spectrometry.     

Identification and evaluation of radiolysis products of irradiated chloramphenicol by HPLC-MS and HPLC-DAD

Summary The radiolysis products of chloramphenicol under γ-radiation sterilization were investigated systematically. Eight main radiolysis products were identified and quantified by HPLC-MS and HPLC-DAD, including two compounds never before reported. The minor radiolysis products were quantified, which shows that they are at concentration levels<threshold for identification. Carbon-carbon rupture reaction and oxidation reaction are proposed as the main radiolysis reactions of chloramphenicol powder. The applicability of γ-sterilization for chloramphenicol products was evaluated quantitatively with qualitative and quantitative data that were compared to the threshold requirements of international regulations for identification. It was concluded that toxicities of the radiolysis products of chloramphenicol produced by γ-radiation sterilization can be neglected, the radiolysis products are safe for human health from the chemical view.     

Study of the mechanism of polysulfone decomposition by pyrolysis/gas chromatography and pyrolysis/gas chromatography/mass spectrometry

Both co- and terpolysulfones have been flash-pyrolyzed at high temperature followed by separation and identification of the products by gas chromatography and/or gas chromatography/mass spectrometry. As expected, most of the products were the corresponding olefin and SO₂. Additionally, higher molecular weight products, including aromatics, and olefin isomerization products, were produced. Mechanisms for initiation and formation of the higher molecular weight products are presented which include the back reaction of intermediate free radicals to abstract hydrogen or to form C? C bonds followed by expulsion of SO₂. The free-radical intermediates formed by the SO₂ expulsion undergo transformations to give the aromatic products. No breakdown products were found with either O or S present, nor was SO₂H found.     

减黏裂化产物的长期储存稳定性

利用不同储存条件下,减黏产物运动黏度、酸值、质量损失、胶质和沥青质含量的变化,研究了委内瑞拉奥里常渣减黏产物长期储存稳定性的影响因素。结果表明,氧化缩聚、轻组分挥发和无氧缩聚作用影响减黏产物的长期储存稳定性,其中氧化缩聚作用最显著。热反应结束后,减黏产物中自由基并没有完全进行链终止反应,室温下自由基继续发生反应,减黏产物的稳定性与其中所含的自由基密切相关。不同储存条件下产物的沥青质和胶质的芳碳率均略低于减黏产物,沥青质间并没有发生缩聚,不易产生分层现象,减黏产物较稳定。     

A study of the composition of solid phases formed in the reaction of titanite with phosphoric acid

The composition and structure of titanium phosphate products formed in decomposition of titanite with phosphoric acid were studied. The sorption capacity of the products obtained for alkali and alkaline-earth elements was determined. The possibility of using phosphate products as titanium-containing pigment fillers was examined.     

Influence of DSC Measurement Conditions on Kinetic Parameters of Thermal Decomposition of 2,4,6-trinitrotoluene

An autocatalytic model involving the limited solubility of volatile catalytic products was applied to the thermal decomposition of 2,4,6-trinitrotoluene. The critical supersaturation of the thermal decomposition products with the catalytic properties was higher at a low heating rate. Decrease of the sample mass led to an increased critical supersaturation of the decomposition products. This is probably a result of the greater contribution of products adsorption on the aluminium pan surface. It is presumed that the differences observed in the rate constant are connected with the uncontrolled critical supersaturation of the volatile thermal decomposition products. This revised version was published online in August 2006 with corrections to the Cover Date.     

Formation of C7-species pyrolysis products from ethylene-propylene heterosequences of poly(ethylene-co-propylene)

Properties of ethylene-propylene copolymer (EPM) are determined by ethylene/propylene ratio and degree of block and random sequences. EPM was pyrolyzed and the pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS) to examine pyrolysis products formed from the ethylene-propylene heterosequences. Pyrolysis products formed from EPM were compared with those formed from polyethylene (PE) and polypropylene (PP) to determine the pyrolysis products formed from ethylene-propylene heterosequences of EPM. Principal pyrolysis products formed from ethylene-propylene heterosequences were 3-methyl-1-hexene, 4-methyl-1-hexene, 2-methyl-1-hexene, and 2-heptene. Order of the relative intensity of the pyrolysis products was 2-methyl-1-hexene > 4-methyl-1-hexene > 3-methyl-1-hexene > 2-heptene. The relative abundances of the pyrolysis products decreased as the pyrolysis temperature increased. Relative abundances of the specific pyrolysis products formed from ethylene-propylene heterosequences may be used for determination of the relative degree of random sequences of EPM as well as ethylene-propylene-diene terpolymer (EPDM).     

Non-volatile products of triolein produced at frying temperatures characterized using liquid chromatography with online mass spectrometric detection.

Oxidation products from triolein under model heated frying conditions have been analyzed using liquid chromatography with an evaporative light scattering detector and atmospheric pressure chemical ionization (APCI) mass spectrometric detection. Triolein was heated at 190 degrees C with 2% water added each hour, to simulate the moisture of a frozen product, until polar components reached approximately 30%. The samples were separated using reversed-phase high-performance liquid chromatography with APCI-MS detection. Triolein oxidation products included hydroperoxides, epoxides and a ketone. Other products were formed by shortening of an acyl chain on the intact triolein. Normal and oxygen-containing products formed by the dimerization of triolein were also observed. Other products included chain addition products formed by addition of acyl chain subunits to intact triolein to form higher molecular weight products.     

五灵脂及其炮制品的微量元素含量测定

为分析五灵脂生药及其炮制品中的微量元素，用电感耦合等离子体发射光谱法（ICP－AES）分析比较了五灵脂及其炮制品中15种微量元素的含量。结果表明，五灵脂生药及其炮制品中富含钙，镁，铁，炮制品可减少铝的溶出。     

Structure elucidation of a condensation product of 4-aminopyrrole derivatives and dicyclohexylcarbodiimide

The chemical structure of the two condensation products of dicyclohexylcarbodiimide (DCC) with the precursors of the mono-pyrrole homologues of distamycin and with the mono and tri-pyrrole homologues of congocidine were established. The two products isolated were proven to be condensation products between 4-aminopyrrole derivatives and dicyclohexylcarbodiimide (DCC).