Synthesis and characterization of copolyesters of PET and substituted p-hydroxybenzoic acids

Random copolyesters of different compositions were synthesized by melt polycondensation of poly(ethylene terephthalate) and 3-bromo - and 3,5-dibromo-p-hydroxybenzoic acids. The copolymer compositions were determined by proton nuclear magnetic resonance spectroscopy. The thermal behavior of these copolyesters was investigated by differential scanning calorimetry. The glass transition temperature, crystallization temperature, and decomposition temperature were found to increase with increase in the paraoxybenzoate content of the copolyesters. The limiting viscosity number and the weight-average molecular weight were determined.     

Thermal and calorimetrical investigations of ordinary and deuterated hydrates of barium acetate

The percentage of thermal dehydration and decomposition of ordinary and deuterated hydrates of barium acetate (tri- and monohydrates) were studied with a derivatograph and by DSC method. The observed phase transitions were identified and their corresponding enthalpy changes determined. The latter were compared with those estimated on thermodynamic data. The conclusions made on the dehydration process in correlation with IR spectra were used as information about the structure of the dehydrated water in the compounds investigated. The end product was also identified as barium carbonate.     

支化聚乙烯的合成及结构与性能

以[ArNC(An)-C(An)NAr]NiBr₂[An=acenaphthyl, Ar=2,6-C₆H₃(ⁱPr)₂]为主催化剂, 以改性甲基铝氧烷(MMAO)和常规的甲基铝氧烷(MAO)为助催化剂, 研究了压力、 温度和时间等条件对乙烯聚合制备支化聚乙烯的影响, 采用高温核磁、 高温凝胶渗透色谱(GPC)及差示扫描量热仪(DSC)等对所得的聚乙烯结构进行表征. 研究发现, 以MMAO为助催化剂时, 催化活性比以MAO为助催化剂时高约1个数量级, 达到10⁷ g/(mol Ni·h); 所得聚乙烯的支化度为(45~64)/1000C, 而以MAO为助催化剂时所得聚乙烯的支化度达(82~88)/1000C. 对支化聚乙烯的力学性能进行了分析, 并与低密度聚乙烯(LDPE)和二元乙丙橡胶(EPM)进行比较. 结果表明, 支化聚乙烯拉伸强度达27.90 MPa, 比LDPE(14.40 MPa)和EPM(5.44 MPa)高, 但支化聚乙烯的弹性模量仅为2.10 MPa, 与EPM(2.11 MPa)相近; 支化聚乙烯的断裂伸长率为774.6%, 略高于LDPE的断裂伸长率(725.6%), 比EPM的断裂伸长率(1770.1%)低.     

南瓜籽烘烤前后化学成分的分析

对烘烤前后南瓜籽中的化学成分进行分析并对比。采用同时蒸馏萃取装置萃取南瓜籽中的挥发性成分,采取超临界CO2萃取技术萃取南瓜籽油脂,并将其分为酸、碱、中性三个部分,用气相色谱-质谱联用方法分析其中化学成分并进行对比。结果表明,南瓜籽挥发性成分中含有多种醛类和酯类化合物,烘烤后产生了大量的烷基吡嗪,其在碱性部分中的相对含量比烘烤前提高14倍多,不饱和醛类化合物含量也有明显提高。南瓜籽油脂中的主要化学成分是油酸、亚油酸及其酯类。还含有生物活性功能成分如植物甾醇、角鲨烯和维生素E等。烘烤后除角鲨烯含量有所降低,维生素E、植物甾醇、亚麻酸等均有提高。     

The enthalpies and heat capacities of hydration of ammonium and tetraalkylammonium bromides

The heat effects of solution of ammonium, tetraethylammonium, and tetrabutylammonium bromides in water were measured over the temperature range 277.15-328.15 K. The standard enthalpies of solution were calculated in the second approximation of the Debye-Hückel theory. The results were compared with the literature data on the enthalpies of solution of tetrabutylammonium and tetrapentylammonium bromides. The applicability of various equations suggested to describe the temperature dependences of enthalpy characteristics was analyzed. Heat capacity changes caused by the hydration of the salts and the temperature dependences of the entropies of hydration were calculated and discussed.     

The enthalpies of formation and sublimation of amino acids and peptides

The experimental enthalpies of formation of L-amino acids and peptides were analyzed using the additive scheme and group contributions. Group contributions to the enthalpies of formation were calculated (increment denotations corresponded to the Benson-Buss symbols). The thermochemical characteristics of a wide range of amino acids and their derivatives were calculated.     

Bond energies and the enthalpies of formation of mono- and polyradicals in nitroalkanes 2. Nitro derivatives of ethane and propane

Based on the experimental results and the published data, the enthalpies of formation of ethane and propane nitro derivatives were obtained for both the standard state and gas phase. The bond dissociation energies of the ethane and propane nitro derivatives were calculated using the enthalpies of atomization and the energies of nonvalent interactions of nitro groups. The calculated values were compared with the kinetic data on thermal decomposition. The bond dissociation energies in radicals of the ethane and propane nitro derivatives were also calculated using the enthalpies of atomization and the energies of nonvalent interactions of nitro groups. Regularities of changes in the bond dissociation energies of the ethane and propane nitro derivatives and their radicals were established.     

Homopolymers and copolymers of acrylates and methacrylates of homoterpenylmethyl carbinol and α-campholenol

Acrylates and methacrylates of homoterpenylmethyl carbinol and α-campholenol were homopolymerized. Copolymers with each other and acrylonitrile were studied. Terpolymers of the acrylate of homoterpenylmethyl carbinol and the acrylate of α-campholenol with butadiene and styrene or acrylonitrile were also prepared. The lactone ring in the homopolymer of methacrylate of homoterpenylmethyl carbinol was opened up under basic conditions at room temperature, yielding a water-soluble polymer. Films of this polymer were cast from a water solution. The acrylate of homoterpenylmethyl carbinol gave a high molecular weight copolymer with acrylonitrile which could be molded into a transparent, extremely tough, film. The terpolymers of the acrylate of homoterpenylmethyl carbinol with butadiene and styrene or acrylonitrile were obtained in high yield and could be molded into strong, rubbery films. Several polymers were epoxidized and cured with p-phenylenediamine.     

Structural modification of sanguinarine and chelerythrine and their antibacterial activity

In this study, five derivatives of sanguinarine (1) and chelerythrine (2) were prepared, with 1 and 2 as starting materials, by reduction, oxidation and nucleophilic addition to the iminium bond C=N+. The structures of all compounds were elucidated on account of their MS, 1H-NMR and 13C-NMR data. The antibacterial activities of all compounds were screened, using Staphylococcus aureus, Escherichia coli, Aeromonas hydrophila and Pasteurella multocida as test bacteria. The minimum bacteriostatic concentration and minimum bactericidal concentration of the active compounds were determined by the turbidity method. The structure-activity relationships of 1 and 2 were discussed. The results showed that 1, 2 and their pseudoalcoholates were found to be potent inhibitors to S. aureus, E. coli and A. hydrophila, while the other derivatives were found to be inactive. The pseudoalcoholates might be the prodrugs of 1 and 2. The iminium bond in the molecules of 1 or 2 was the determinant for antibacterial activity, and the substituents at the 7 and 8 positions influenced the antibacterial activities of 1 and 2 against different bacteria.     

Preparation and properties of mixed micelles made of Pluronic polymer and PEG-PE

Mixed micelles made of Pluronic P105 (P105) and poly(ethylene glycol)-phosphatidyl ethanolamine conjugate (PEG-PE) were prepared. The interaction of Pluronic and PEG-PE was studied and the interaction parameter beta and critical micelle concentration (CMC) were used to evaluate the micellar stability toward dilution. The results showed that certain mixed micelles were more stable than pure Pluronic micelles upon dilution. The mixed micelles were used to trap the poorly soluble anticancer drug camptothecin (CPT). The cytotoxicity of the CPT-loaded mixed micelles against MCF-7 cancer cell was higher than that of CPT-loaded P105 micelles and much higher than that of the free drug.     

HDEHP和HEHEHP界面性质及添加剂对界面性质的影响

测定了HDEHP、HEHEHP、TOPO、TBP、SDS和CTMAB的煤油溶液与硫酸盐水溶液所构成的液-液体系的界面张力,考察了水相pH对界面张力的影响,求得这些化合物的界面吸附常数,计算出饱和吸附时界面吸附分子的截面积,提出了用Cmin计算活性剂分配比的方法,研究了向HDEHP或HEHEHP体系中添加TOPO(或TBP)、SDS、CTMAB时界面张力的变化及其对萃取速率的影响。界面化学反应控制的萃取金属阳离子过程的速率将因添加剂占据界面和(或)形成界面负电层而降低,因添加剂与萃取剂形成界面活性较强的分子缔合物对金属的萃取而提高。     

Evaluation of process conditions and characterization of particle size and stability of oil-in-water nanoemulsions

This article reports on the oil in water (o/w) nanoemulsions, which were prepared using a mixture of solvents (decane, toluene and cyclohexane) as oils and the mixtures of ethoxylated lauryl alcohols with various concentrations as surfactants with HLB values ranged from 10 to 12. The Ultra-Turrax (rotor-stator type) stirring and/or ultrasound processing were applied for varied processing times. The data show that the particle sizes in nanoemulsions prepared with ultrasound were smaller than those produced by stirring. The stability of these emulsions was, however, enhanced, when the mixtures were preliminary processed with the shearing agitator. The most stable nanoemulsions were obtained in 10 wt % surfactant mixture of the alcohols with HLB 11 in the shearing agitator.     

Synthesis and properties of polymeric azine and thiazine dyes

Some polymeric azine or thiazine dyes were prepared by radical polymerization of dye monomers or by polymer reactions between dyes and suitable prepolymers, and their photoredox reactivities were studied. The thionine polymers containing labile ? OH groups exhibited photochromism and thermochromism, which were extremely sensitive to the moisture content of the polymer film. The reversibility of the photochromism and thermochromism increased with the water content in the film. The water-soluble polymeric dyes were photobleached under the influence of suitable reducing agents. The degree of photobleaching was smaller than for the monomeric systems except for the dye polymers containing ? OH groups, probably because of the large steric hindrance of the polymers.     

Preparation and characterization of thin films of monomeric and polymeric octacyanophthalocyanines

Thin films were prepared on substrates, cleavage surface of KCl single crystal, and metallic copper, by reaction of 1,2,4,5-tetracyanobenzene with the substrate at various temperatures. The films were characterized by elemental analysis, IR, and UV/VIS spectroscopies. The films were observed by scanning electron microscopy. The films produced on copper at temperatures between 300 and 400°C consisted of copper octacyanophthalocyanine and its polymer with ladder structure. The ratio of polymer to monomer increased with elevating the reaction temperature. The films were composed of ribbon-like crystals. The film produced on copper above 450°C was composed of an amorphous and continuous layer of polymeric copper phthalocyanine. The film produced on KCl at temperatures between 250 and 350°C consisted of potassium octacyanophthalocyanine and its polymer with ladder structure. The film produced on KCl above 450°C was polymeric potassium phthalocyanine. Those films contained more metal content than that required stoichiometrical.     

用微机估算单体及其聚合反应的焓与熵

采用ABW (Anderson Beyer Watson)基团贡献法 ,通过建立数据库、计算机编程 ,分别在UC DOS 6.0环境、MicrosoftFoxPro 2 .6编辑平台和Windows 95环境、BorlandDelphi 3.0编辑平台上运行。对常见烯类单体及其聚合反应的焓与熵进行估算 ,其结果与文献值很接近、操作简单、显示直观。     

Synthesis and vibrational spectroscopy of halotrichite and bilinite

The new uranyl complexes with tetradentate unsymmetrical N₂O₂ Schiff base ligands were synthesized and characterized by IR, UV–vis, NMR and elemental analysis. The DMF solvent is coordinated to uranyl complexes. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the uranyl complexes were carried out in the range of 20–700 °C. The UO₂L¹ complex was decomposed in two and the others were decomposed in three stages. Up to 100 °C, the coordinated solvent was released then the Schiff base ligands were decomposed in one or two steps. Decomposition of synthesized complexes is related to the Schiff base characteristics. The thermal decomposition reaction is first order for the studied complexes.     

六芳基二咪唑类化合物的合成及光致变色性能

六芳基咪唑;六芳基二咪唑类化合物的合成及光致变色性能     

Quantification of polyphenols and flavonoid content and evaluation of anti-inflammatory and antimicrobial activities of Stenocereus stellatus extracts

The hexanic, ethyl acetate and methanolic extracts from branches of Stenocereus stellatus were tested in both the 12-O-tetradecanoylphorbol-13-acetate (TPA) – induced ear oedema model and antimicrobial activity assay. The % of oedema inhibition, the Minimum Inhibitory Concentration (MIC), as well as the polyphenolic and flavonoid content were determined. Also, extracts were analysed by gas chromatography–mass spectrometry (GC–MS). In TPA model, the three extracts showed moderate oedema inhibition. In the antimicrobial activity assay, methanolic extract shows better MIC against all strains. The lowest MICs were for Candida albicans (31 μg/mL) and Rhizopus sp. (15 μg/mL). Also, 50.78 mg eq. of gallic acid/g extract of polyphenol and 115.12 mg eq. of catequine/g extract of flavonoids content were founded in ethyl acetate extract. In the chromatographic analysis, β-sitosterol, β-amyrine, betulin and some other molecules were identified. The results show that S. stellatus possess antimicrobial activities against some fungus species.     

理化实验室的设计与建设

以某新建理化实验室为例,阐述了实验室的建设过程,指出了建设理化实验室的设计思想和遵循原则：介绍了普通理化实验室设计与建设过程中必备的功能区域及基本要求;从电力系统、通风系统、供排水和供排气系统几方面探讨了筹建理化实验室的设计思想,强调了合理规划设计对实验室长期可靠运行的重要性。     

聚合松香的制备及其含量测定

以工业松香为原料,用硫酸-无水氯化锌作催化剂制备聚合松香.在70℃下,用甲苯溶解松香(松香和甲苯的重量比为1∶1),加入n(H2SO4)∶n(ZnCl2)=0.6的催化剂,120℃温度聚合反应10 h和270℃减压蒸馏(200 Pa)的条件下,所得一级聚合松香的二聚松香的含量≥90.5%,软化点182℃,酸值150.6 mg KOH/g,收率≥74%;二级聚合的二聚松香的含量≥65%,软化点135℃,酸值157 mg KOH/g,收率≥95%.用GC-MS分离出二聚体中的14个异构体;通过测定松香单体和二聚体的相对校正因子,采用面积归一法测定产品二聚体的含量.