Enhancement of the enzymatic digestibility of waste newspaper using tween

Methods of increasing the enzymatic digestibility of waste newspaper by adding Tween (TW)-20 and 80 surfactants were investigated. Tween-series surfactants were selected because these surfactants increase cellulase activity during enzymatic hydrolysis and do not inhibit cell growth in downstream fermentation processes. When surfactant was used in a pretreatment, a benefic effect was expected in the enzymatic hydrolysis stage owing to surfactant carry-over from the pretreatment stage immediately upstream of the hydrolysis. However, because it was necessary to wash the pretreated substrate with water to remove inhibitors produced during pretreatment, no added benefit was obtained. When surfactant was used in the pretreatment only, it was found that it had a marked effect on digestibility and that this effect was higher at lower enzyme loadings. Also, TW-80 was found to be more effective than TW-20, and the addition of enzyme and TW-80 to substrate at the beginning of enzyme reaction was found to most effectively increase digestibility. When TW-80 was added into either the pretreatment stage or the hydrolysis stage the digestibilities of untreated sample increased by approx 40%, whereas an increase of only 45% was observed when TW-80 was added to both stages. These results show that the addition of surfactant to either the pretreatment or the enzymatic hydrolysis stage is sufficient to increase digestibility.     

比对法在计量标准考核验证中的应用探讨

为探讨比对法在计量标准考核验证中的可行性,将5家实验室分别对同一分度吸量管的检定结果进行比对,同时采用具有溯源性的传递比较法进一步验证比对法的可靠性。验证结果显示,采用比对法和传递比较法对被考核实验室的验证结果一致,说明采用比对法对检定结果的验证是有效的、可行的。     

统计方法在微量金分析中的应用

化探金样品前处理过程中消解、富集、解吸等环节控制不严格,往往会导致最后数据处理产生过高的校正系数。为了降低校正系数,用统计学的方法对实验过程进行了详细分析,确定了主要影响因素。将水浴时间延长并保温3 h以上,泡塑大小改为0.2 g,清洗时间不大于15 s,解吸到上机时间间隔小于5 h。方法改进后,检测结果校正系数有了明显改善,从改进前有40%批次的校正系数大于1.2,降到了全部小于1.2,甚至不用校正。方法改进后降低了实验过程的误差,提高了分析测试结果的稳定性。     

Cardiovascular effects of mycelium extract of Ganoderma lucidum: inhibition of sympathetic outflow as a mechanism of its hypotensive action

In an effort to understand the mechanism of cardiovascular actions of Ganoderma lucidum which was cultivated in Korea, the mycelium was isolated for a large-scale culture. Water extract of the mycelia was evaluated for its cardiovascular activity in anesthetized rabbits and rats. The left femoral artery and vein were cannulated for the measurement of arterial pressure and subsequent delivery of drugs. The left kidney was exposed retroperitoneally and a branch of the renal nerve was used to integrate renal efferent or afferent nerve activities. The extract decreased systolic and diastolic blood pressure, which was accompanied by an inhibition of renal efferent sympathetic nerve activity. The extract did not decrease heart rate in these animals, although there was clear hypotension in the extract dose dependent manner. This suggests that the hypotension induced by the treatment of the extract was secondary to the primary effect of the extract in the central nerve system, which suppressed the sympathetic outflow. Therefore we concluded that the mechanism of hypotensive action of Ganoderma lucidum was due to its central inhibition of sympathetic nerve activity.     

纳米催化剂在CO_(2)加氢制甲醇中的研究进展北大核心CSCD

为减缓温室效应,将CO_(2)转换成高附加值的甲醇是减少CO_(2)排放的有效途径,而高效催化剂是CO_(2)加氢制甲醇反应规模化的关键.可调控合成的具有量子尺寸效应的纳米催化剂在该反应上具有独特的优势.因此我们深入探讨了反应机理,综述了纳米材料在CO_(2)加氢制甲醇中的研究进展,最后给出了高效催化剂可能的发展方向.     

1,1,3,3-四(全氟己基乙基)二锡氧烷二聚体在环氧化合物开环反应中的催化作用

采用氟碳-有机溶剂两相催化体系,考察了1,1,3,3-四(全氟己基乙基)二锡氧烷二聚体(1)在环氧化合物开环反应中的催化作用.结果表明,催化剂(1)在氟碳-有机溶剂两相体系中使环氧苯乙烯和甲醇的开环反应产率高达95%,¹³CNMR谱表明,开环反应的区域选择性为100%.在氟碳-有机溶剂两相催化体系中以一锅法制备了3-苯基丙酸2-甲氧基-2-苯乙醇酯,收率高,方法简便,催化剂几乎可以定量回收循环使用.     

The catalytic role of uranyl in formation of polycatechol complexes

To better understand the association of contaminant uranium with natural organic matter (NOM) and the fate of uranium in ground water, spectroscopic studies of uranium complexation with catechol were conducted. Catechol provides a model for ubiquitous functional groups present in NOM. Liquid samples were analyzed using Raman, FTIR, and UV-Vis spectroscopy. Catechol was found to polymerize in presence of uranyl ions. Polymerization in presence of uranyl was compared to reactions in the presence of molybdate, another oxyion, and self polymerization of catechol at high pH. The effect of time and dissolved oxygen were also studied. It was found that oxygen was required for self-polymerization at elevated pH. The potential formation of phenoxy radicals as well as quinones was monitored. The benzene ring was found to be intact after polymerization. No evidence for formation of ether bonds was found, suggesting polymerization was due to formation of C-C bonds between catechol ligands. Uranyl was found to form outer sphere complexes with catechol at initial stages but over time (six months) polycatechol complexes were formed and precipitated from solution (forming humic-like material) while uranyl ions remained in solution. Our studies show that uranyl acts as a catalyst in catechol-polymerization.     

Development of SPE for recovery of polysaccharides and its application to the determination of monosaccharides composition of the polysaccharide sample of a lactobacillus KLB 58

A new SPE cartridge has been prepared in this study to purify polysaccharides of high molecular weights. A porous nonpolar styrene-divinylbenzene copolymer phase (Hamilton PRP-1) was used to make the new cartridge. The cartridge was conditioned with methanol, water, and ACN in sequence, and the sample dissolved in a small amount of water was loaded. Impurities of low molecular weights were removed first by elution of 80:20 or 90:10 v/v% ACN/water, and polysaccharides were quantitatively recovered by elution of 50:50 v/v% ACN/water or pure water. The recovery of pure dextran 10000 was 90-95%. The SPE method was applied to purification of the polysaccharide sample of KLB58, a new lactobacillus discovered in Korea. The purified KLB 58 sample (weight recovery after SPE purification; 60%) was hydrolyzed for analysis of composition of monosaccharides. The hydrolysate was found to be composed primarily of fructose, glucose, galactose, rhamnose, mannose with small amounts of fucose and ribose.     

Apparent increase of insulin peak area in HPLC analysis of a preparation consisting of a mixture of insulin and total parenteral nutrition

The peak area of insulin in a mixture of K.C.L. injection and hyperalimentation fluid was found to increase in a time dependent manner up to 24 h in measurement by a high-performance liquid chromatograph. The increase of peak area corresponding to the insulin was detected at wavelengths of both 210 and 280 nm. This increase was only observed in the presence of the sugars, tryptophan, riboflavin, and insulin, and ascorbate was shown to counteract the increase. These results suggest the possibility that insulin forms a mixture caused by the oxidation reaction in a hyperalimentation fluid.     

导数测量技术在气相色谱信号处理中的应用

介绍了导数测量技术在气相色谱信号处理中的应用。导数-气相色谱的热导检测器对苯的灵敏度和敏感度分别达到270kV·L/kg和0.3μg／L。与可分辨导数色谱峰相对应的常规色谱峰最小分离度为2．8。在被测组分质量浓度为8．1～810g／L的范围内,导数峰上峰高、下峰高、总峰高、峰面积均与质量浓度呈线性关系,其线性相关系数分别为0．9911,0．9982,0．9960和0.9991。     

LC Evaluation of Intestinal Transport of Praziquantel

Praziquantel (PZQ) is a highly lipophilic drug with low aqueous solubility. Despite this, it is well absorbed from the gastrointestinal tract. In this study, a simple LC method was developed and validated, in order to monitor the concentration of PZQ in TC-199 buffer in vitro, in the rat everted gut sac absorption model. PZQ was analyzed by a reversed-phase LC method with an isocratic mobile phase containing acetonitrile and water in the proportions 45:55. The flow-rate was 1 mL min⁻¹ and PZQ was determined by measuring absorbance at 215 nm, at 25 °C. The method was found to be specific, as none of the components of TC-199 or intestinal sac artefacts interfered with the drug peak. Recovery was within acceptable statistical limits. The limit of detection was 0.54 μg mL⁻¹ and the limit of quantitation was 1.63 μg mL⁻¹. The calibration curve was found to be linear in the concentration range of 10–90 μg mL⁻¹ PZQ. The proposed method was found to be rapid and selective and hence can be applied in the monitoring of the absorption of PZQ in in vitro everted gut sac absorption studies.

     

活化条件对负载Ru催化剂的Ru粒子化学环境的影响

本文应用动态脉冲吸附技术测定了H_2和CO的吸附量,结合透射电镜(TEM)和程序升温还原(TPR)等表征技术考察了活化条件对金属Ru粒子化学环境的影响.发现活化条件对Ru催化剂H_2和CO吸附量的影响很显著,H_2和CO低温吸附量随焙烧温度的升高而锐减;改由在惰性气体中焙烧或载体经HCI或HF预处理,大大增加了低温吸附量.TEM测定结果表明:金属Ru平均粒径(?)值随焙烧温度(在623K以下的范围内)的升高而减小,说明在此活化条件下处理的催化剂,其低温H_2和CO化学吸附量不能反映金属的分散度.TPR结果说明在空气中焙烧催化剂,Ru非氧化物前身转变成为RuO_2,并且导致金属与载体之间产生较强的相互作用,改变金属Ru粒子的化学环境,吸附活化能垒增高,在低温下H_2和CO的吸附量很小.     

Fundamental study of the influence of pixel size on the quality of scintigrams

The effect of pixel size on image quality was investigated. The image quality was examined by abnormality detection and image preference for clinical images displayed with different pixel sizes. Smaller pixel size was found to be superior to large one in image quality using large field of gamma camera (FWHM 6.42 mm), 1.6mm pixel size (a 256 x 256 matrix) was found to be the best in image quality. Examined image minification effect, 3.2 mm pixel size (image size: 5 cm phi) was found to be superior to 1.6 mm pixel size (image size: 10 cm phi) in image preference and to be almost equal to 1.6 pixel size in abnormality detection.     

Mechanism of Thermal Decomposition of Barium Benzoate

Barium benzoate was synthesized in a hydrothermal reaction. The complex was characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. It was monoclinic and had a layered structure. The mechanism of thermal decomposition of the barium benzoate was studied by using TG, DTA, IR and gas chromatography-mass spectrometry. In a nitrogen atmosphere, the barium benzoate decomposed to form BaCO₃ and organic compounds: mainly benzophenone, triphenylmethane, etc.This revised version was published online in November 2005 with corrections to the Cover Date.     

Synthesis of PANI and Study of Morphology in the Process of Polymerization

The polyaniline micro/nanostructure was prepared by a self‐assembly process with molybdic acid as dopants in the presence of ammonium persulfate as the oxidant. It was found that the morphology of PANI micro/nanostructure was affected by the concentration of the dopant, that is, the morphology of PANI changed from nanofibers to co‐existence of nanofibers and microspheres as the molar ratio of molybdic acid to aniline varied from 0.01 to 1.5. Under the same condition it was also found that the conductivity value of PANI enhanced from 4.58×10^?3 S·cm^?1 to 3.8×10^?1 S·cm^?1. The structure of PANI was characterized by FTIR and XRD which confirmed the presence of the molybdic acid in the PANI. The electrochemical characteristics of the PANI nanofibers were investigated by means of cyclic voltammetry. The morphology of PANI in the process of polymerization was characterized by SEM. It was found that when the molar ratio of molybdic acid to aniline was 0.3, the morphology of PANI was co‐existence of nanofibers and microspheres and the formation of microspheres was ahead of the nanofibers.     

Hydrolysis of dextrin in the presence of block copolymer of vinyl alcohol and styrenesulfonic acid

A block copolymer of vinyl alcohol and styrenesulfonic acid was prepared by a two-step polymerization and subsequent modification, and its catalytic activity on the hydrolysis of dextrin was investigated. The hydrolysis rate in the presence of the copolymer containing more vinyl alcohol-repeating units was found to follow Michaelis–Menten-type kinetics, whereas that in the presence of a copolymer containing fewer vinyl alcohol units proceeded according to ordinary second-order kinetics. The process of complex formation for the former system was characterized by pronounced decreases in enthalpy and entropy, although the enthalpy and the entropy of activation for the decomposition of the complex to product was comparable to that of a sulfuric acid-catalyzed system. The maximum rate enhancement obtained in the present experiment was approximately fivefold on the basis of the reaction in the presence of sulfuric acid at 65°C. The results were compared with those obtained in the presence of a random copolymer catalyst, previously reported.     

Determination of the critical parameters of polymer solutions

The contribution of short-range orientation order to the chemical potentials of components in a polymer-solvent system was determined. The temperature dependence of the degree of orientation of solvent molecules relative to polymer chains in a polyisobutylene-benzene system was obtained. It was shown that the short-range order in the polymer-solvent system fails with temperature to a much lesser extent than in the pure solvent. The expressions for the upper and lower critical solution temperatures with allowance for the contribution of short-range order to the entropy and the free energy of solution, as well as to the chemical potentials of components, were found. It was demonstrated that, in the polymer-solvent system, two upper and two lower critical solution temperatures can exist.     

电感耦合等离子体原子发射光谱法测定钒铁中8个杂质元素含量和方法精密度的验证

提出了电感耦合等离子体原子发射光谱法(ICP-AES)测定钒铁中硅、磷、铝、锰、镍、铬、铜、钛共8个杂质元素含量的方法。钒铁样品(0.5000g),先后加入50%(体积分数)硝酸溶液20mL及50%(体积分数)盐酸溶液10mL,在100℃左右加热溶解,溶解过程中应注意保持溶液体积在25mL左右。将溶液过滤并置于200mL容量瓶中作为母液留用。将滤纸及不溶物一并移入铂坩埚中,置于马弗炉中,先于250℃灰化20min,稍冷后加入无水碳酸钠和硼酸(质量比2∶1)组成的混合熔剂0.3g,升温至950℃融熔15min。冷却,用体积比1∶10的盐酸溶液10mL浸出熔块,将此溶液与上述母液合并并加水定容至200mL。此溶液供ICP-AES在仪器工作条件下进行分析。绘制校准曲线时,加入纯铁和五氧化二钒作为基体,以消除基体干扰,然后加入上述8种元素的标准溶液,并按上述溶液最终稀释体积条件和仪器工作条件制作曲线(R大于0.999)。为验证所提出的分析方法的测定数据的精密度,约请了10个实验室对8个不同含量水平的钒铁样品对方法作协同试验,按GB/T 6379.2-2004所规定的方法求算了重复性标准偏差Sr和重复性限r,以及再现性标准偏差SR和再现性限R,并求得所测定的8种元素在各自的测定范围内的r与w之间和R与w之间的函数关系,说明该方法有较好的稳定性和准确性,而且证明此方法是可行的。     

A total synthesis of hydroxylysine in protected form and investigations of the reductive opening of p-methoxybenzylidene acetals

A synthesis of (2S,5R)-5-hydoxylysine, based on (R)-malic acid and Williams glycine template as chiral precursors, has been developed. This afforded hydroxylysine, suitably protected for direct use in peptide synthesis, in 32% yield over the 13-step sequence. Regioselective reductive opening of a p-methoxybenzylidene acetal and alkylation of the Williams glycine template were key steps in the synthetic sequence. Surprisingly, the regioselectivity in opening of the p-methoxybenzylidene acetal was reversed as compared to what was expected. It was found that this was due to chelation of the trialkylsilyl choride, used as an electrophile in the reductive opening, to an adjacent azide functionality. It was also discovered that an equivalent amount of trialkylsilyl hydride was formed in the reaction, a finding that led to additional mechanistic insight into reductive openings of p-methoxybenzylidene acetals with sodium cyanoborohydride as reducing agent.     

Radical Polymerization of Maleic Acid by Potassium Persulfate in the Presence of Polyvinylpyrrolidone in Water

Maleic acid(MA) was found to polymerize easily by potassium persulfate (KPS) in water in the presence of polyvinylpyrrolidone (PVP), and to form a polymer complex in which the molar ratio of MA to VP monomer unit was approximately unity. The formation of the polymer complex was accelerated by increases in the reaction temperature, in the concentrations of KPS and MA, and in the molecular weight of PVP used. Thermal degradation behavior of the polymer complex was studied thermo-gravimetrically. The thermagram of the polymer complex was substantially different from those of PVP and the 1:1 mixture of MA and PVP. It was found that the poly-MA portion of the polymer complex decomposed at 100-300°C, while the PVP portion underwent degradation at 350-500°C. In order to separate poly-MA from the polymer complex, the polymer complex was methylated by diazomethane, and 50 ～ 60% of the poly-MA part in the polymer complex was separated as its methyl ester, which was found to be oligomer (M = 400 ～ 500) by GPC. Unseparated part of poly-MA seems to be grafted onto PVP. The polymerization of citraconic acid (CA) was also performed in the same manner. Similar results were obtained, though the polymerization of CA was slower as compared with that of MA.