甲基红共振瑞利散射法测定肝素钠

肝素钠（Hep）系葡糖胺聚糖,是蛋白多糖的一种,它具有广泛的生物学功能,是重要的生化药物之一。对不同的疾病,有不同的最适剂量,临床上需进行监控。因此,研究肝素的定量测定方法是非常重要的。肝素的测定最常采用的是生物方法。此外,化学方法有分光光度法、HPLC法,毛细管电泳法,电化学传感器。在国内外利用共振瑞利散射测试肝素钠的也有报道,一般都采用了稀土高价阳离子作增色剂。本文采用的是一种价格便宜的甲基红（methylred）染料作增色剂,结果表明：在近中性的B—R缓冲溶液中,肝素钠与甲基红染料形成离子缔合物后,RRS强度显著增强,并产生了新的RRS光谱;且在一定范围内,RRS强度与肝素钠浓度成正比。在0．060μg/mL～4．00μg/mL范围内呈良好的线形关系,由此对肝素钠注射液进行效价分析,并用此方法测定人体血清中的肝素钠含量,测得人体血清中肝素钠含量为9．18mg／100mL,回收率在90％以上。显然,此法对肝素钠的测定是可靠、灵敏而实用的。     

Synthesis and Crystal Structure of Methyl 12-Bromo- 13,14-furoxan-deisopropyldehydroabietate

1 INTRODUCTION Pine resin is a very abundant renewable natural source mainly composed of diterpenic resin acids with the general formula C19H29COOH, which has been widely applied in industrial manufactures and fine chemicals[1]. Recently, a series of research re- sults show that the resin acid derivatives are poten- tially useful intermediates in the synthesis of drugs active against viruses[2～5]. Their antiviral activity and function as nucleoside analogues or non- nucleoside inhibito…     

The Antioxidant,Cytotoxic and Antimicrobial Potential of Phenolic Acids-Enriched Extract of Elicited Hairy Roots of Salvia bulleyana

Hairy root cultures are valuable sources of a range of phytochemicals. Among them, Salvia bulleyana root culture is a promising source of polyphenols, especially rosmarinic acid (RA), a phenolic acid depside with pleiotropic activity and a wide application in medicine and cosmetology. The aim of the study was to enhance the culture productivity by finding suitable elicitation protocol and to determine its biological potential in terms of antioxidant, anticancer and antimicrobial properties. The total content of phenols and the levels of particular constituents in root extracts were analyzed using HPLC-PDA. Among four elicitors tested (yeast extract; methyl jasmonate, MJA; trans-anethol; and cadmium chloride), MJA was found to be the most effective. The greatest boost in phenolic production (up to 124.4 mg/g dry weight) was observed after three-day treatment with MJA at 100 µM, with an almost 100% improvement compared to the controls (non-treated root culture). The hydromethanolic extract from the elicited culture exhibited strong antioxidant activity with IC₅₀ values of 11.1 µg/mL, 6.5 µg/mL and 69.5 µg/mL for DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid)) and superoxide anion radical, respectively. Moreover, in concentrations of 0.5–5 mg/mL the extract inhibited the growth of LoVo, AGS and HeLa cell lines, but was safe for the L929 cells up to the concentration of 5 mg/mL. The extract also exhibited moderate antimicrobial activity. Thus, the results confirmed that elicitation can be a beneficial strategy for increase the phenolic acid biosynthesis in hairy roots of S. bulleyana, and that such a highly productive culture can show significant biological potential.     

On the evidence of crosslinking in methyl pendent PBZT fiber

In order to influence the compressive strength of the rigid rod polymeric fibers, methyl pendent poly(p-phenylene benzobisthiazole) fibers have been heat treated in the 400 to 550°C temperature range in air and in nitrogen for varying times to achieve intermolecular crosslinking. These fibers have been examined using Fourier transform infrared (FTIR) spectroscopy, ¹³C solid-state nuclear magnetic resonance (NMR) swelling behavior, and scanning electron microscopy. ¹³C NMR has also been carried out on solutions of as-spun fibers. Fibers heat-treated at 400°C, both in nitrogen and in air, up to heat-treatment times of 60 min are insoluble in 99% chlorosulfonic acid, however no direct evidence of crosslinking has been obtained for these fibers using spectroscopic techniques, suggesting that in these fibers the degree of crosslinking must be very low. Evidence that methyl groups are precursors to certain crosslinks was first seen via a weak methylene resonance in ¹³C solid-state NMR, corresponding to about 2% of the original methyl intensity, in a sample heat-treated at 450°C in air. Fibers heat-treated in nitrogen at 550°C for 10 minutes do not exhibit any swelling in chlorosulfonic acid, are brittle, have lost most methyl groups; however, some CH₂ groups form. In this fiber, the carbon intensity for the CH₂ group in the ¹³C solid-state NMR is 18% of the intensity for the CH₃ group in the as-spun fiber. The fibers heat-treated at 400 and 450°C show a fibrillar morphology, while the fibrillar morphology is not observed in the fibers heat-treated at 550°C in nitrogen for 10 min. Based on this work, it is our judgment that if heat treatment of this material is to improve compressive strength, the heat treatment protocol of time and temperature will probably be critical and the highest temperatures of exposure will probably lie in the 450 to 550°C range. © 1996 John Wiley & Sons, Inc.     

Volatile Organic Compounds from Bacillus aryabhattai MCCC 1K02966 with Multiple Modes against Meloidogyne incognita

Plant-parasitic nematodes cause severe losses to crop production and economies all over the world. Bacillus aryabhattai MCCC 1K02966, a deep-sea bacterium, was obtained from the Southwest Indian Ocean and showed nematicidal and fumigant activities against Meloidogyne incognita in vitro. The nematicidal volatile organic compounds (VOCs) from the fermentation broth of B. aryabhattai MCCC 1K02966 were investigated further using solid-phase microextraction gas chromatography-mass spectrometry. Four VOCs, namely, pentane, 1-butanol, methyl thioacetate, and dimethyl disulfide, were identified in the fermentation broth. Among these VOCs, methyl thioacetate exhibited multiple nematicidal activities, including contact nematicidal, fumigant, and repellent activities against M. incognita. Methyl thioacetate showed a significant contact nematicidal activity with 87.90% mortality at 0.01 mg/mL by 72 h, fumigant activity in mortality 91.10% at 1 mg/mL by 48 h, and repellent activity at 0.01–10 mg/mL. In addition, methyl thioacetate exhibited 80–100% egg-hatching inhibition on the 7th day over the range of 0.5 mg/mL to 5 mg/mL. These results showed that methyl thioacetate from MCCC 1K02966 control M. incognita with multiple nematicidal modes and can be used as a potential biological control agent.     

Characterization of azo-containing polydimethylsiloxanes and their copolymers with methyl methacrylate

Azo group-containing polydimethylsiloxanes (PDMS–ACP), macroazoinitiators, were prepared by polycondensation reaction of 4,4′-azobis-4-cyanopentanoyl chloride (ACPC) with hydroxybutyl-terminated polydimethylsiloxane (PDMS) of varying molecular weights. The activation energy (E_a), activation enthalpy (ΔH^‡), and activation entropy (ΔS^‡) of the thermodecomposition of PDMS-ACP in toluene increased with increase in poly-dimethyl-siloxane chain length (SCL) in PDMS moieties, while the activation free energy (ΔG^‡) was independent on the SCL. The polydimethylsiloxane-poly(methyl methacrylate) block copolymers (PDMS-b-PMMA) were prepared by the use of PDMS-ACP macroazoinitiators, and they were characterized by ¹H-, ²⁹Si-, and ¹³C-nuclear magnetic resonance (NMR) spectroscopies. The microstructure and morphology of copolymers were investigated by proton spin–spin relaxation measurements and scanning electron microscopy (SEM). © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of amphiphilic diblock copolymers of methyl tri(ethylene glycol) vinyl ether and isobutyl vinyl ether

Water-soluble diblock copolymers of methyl tri(ethylene glycol) vinyl ether (hydrophilic block) and isobutyl vinyl ether (hydrophobic block) of different molecular weights and composition were synthesized by living cationic polymerization. The molecular weight and comonomer composition of these copolymers were determined by GPC and ¹H NMR spectroscopy, respectively. Aqueous solutions of the copolymers were characterized in terms of their micellar behavior using dynamic light scattering, aqueous GPC, and dye solubilization. All the copolymers formed aggregates with the exception of a diblock copolymer with only two hydrophobic monomer units. The micellar hydrodynamic size scaled with the 0.61 power of the number of hydrophobic units, in good agreement with a theoretical exponent of 0.73. An increase in the length of the hydrophobic block at constant hydrophilic block length or an increase in the overall polymer size at constant block length ratio both resulted in lower critical micelle concentrations (cmcs). The cloud points of 1% w/w aqueous solutions of the polymers were determined by turbidimetry. An increase in the length of the hydrophobic block at constant hydrophilic block length caused a decrease in the cloud points of the copolymers. However, an increase in the overall polymer size at constant block length ratio led to an increase in the cloud point. © 1996 John Wiley & Sons, Inc.     

A systematic approach to the study of multicomponent polymerization kinetics: The butyl acrylate/methyl methacrylate/vinyl acetate example. IV. Optimal Bayesian design of emulsion terpolymerization experiments in a pilot plant reactor

A systematic study of the terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate (BA/MMA/VAc) is being conducted. In this stage of the study, emulsion terpolymerizations were performed in a 5 L stainless steel pilot plant reactor. The experimental trials were of the two-level factorial type and were designed optimally using a Bayesian method. The design procedure allowed us to improve our knowledge about the process using our prior knowledge and our subjective judgement. The polymers produced were characterized for conversion, composition, molecular weight, and particle size. The Bayesian design of experiments is shown to have several advantages over conventional factorial designs. © 1996 John Wiley & Sons, Inc.