Osteryoung square wave voltammetric determination of lactose in food samples by a derivative procedure

A method for determination of lactose in food samples by Osteryoung square wave voltammetry （OSWV） was developed. It was based on the nucleophilic addition reaction between lactose and aqua ammonia. The carbonyl group of lactose can be changed into imido group, and this increases the electrochemical activity in reduction and the sensitivity. The optimal condition for the nucleophilic addition reaction was investigated and it was found that in NH4C1-NH3 buffer of pH 10.1, the linear range between the peak current and the concentration of lactose was 0.6-8.4 mg L-l, and the detection limits was 0.44 mg L- 1. The proposed method was applied to the ＇determination of lactose in food samples and satisfactory results were obtained.     

Synthesis of 3-Methylbutanal by Strecker Reaction at Unelevated Temperature and in Acidic Systems

It was reported that3-methylbutanal was an important volatile compound in dry-cured ham products1-3.It has been associated with nutty,cheesy and salty notes in Parma ham4and correlated with the aged flavor of hams5.It is also maybe one of the reasons for …     

Pd-gate MOS sensor for detection of methanol and propanol

The present paper focused on the detection of methanol and propanol using Pd-gate metal-oxide-semiconductor (MOS) sensor. Surface mor- phology and composition of the gate film were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The response of the sensor for propanol and methanol was measured as shift in capacitance-voltage (C-V) and conductance-voltage (G-V) curves of the MOS structure. The sensitivity of the sensor towards methanol was found to be greater than that towards propanol. It was 58.2% for methanol and 32% for propanol (at 0.6 V, 1 MHz) in terms of capacitance measurements, while in terms of conductance results the sensitivity was found to be 57.2% for methanol and 38.9% for propanol at 1 kHz. The discontinuities or cracks present in the microstructure of the gate material are believed to be mainly responsible for the high sensitivity of the sensor, going with the decomposition of gas molecules and subsequent hydrogen permeation through Pd.     

FOURIER TRANSFORM INFRARED STUDY OF FRACTIONATED AROMATIC POLYESTERS

Infrared spectra at different temperatures have been studied for fractions ofa liquid crystal tormmg aromatic polyester. The molecular interactions in different phases and their changes duringthe transitions were discussed. Abrupt frequency shift was found for bands of groups both in mesogens and flexible spacers during fusion and isotropization transitions. It may imply that both the mesogens and the flexible spacers are included in the same crystalline phase and give their contributions to the formation of the mesophase. The splitting into doublet of the C—O stretching vibrations was observed for both the aromatic and aliphatic esters and was attributed to the existence of local regions for ester groups different in ordering. The more ordered regions do not disappear completely even in the isotropic liquid phase.     

高效液相色谱手性固定相的研究 I:L-缬氨酸-叔丁酰胺型固定相的制备及对映体拆分

A new chiral chemically bonded stationary phase for direct resolution of optical isomers in HPLC was prepared. The experiemental data showed that the chiral stationary phase gave good resolution for the racemic α-amino acid derivatives and that there was no significant influence on the resolution as the eluting rate varied from 0.6 to 2.0 mL/min. The content of isopropanol in the eluent significantly affected the resolution of the enantiomers. The eluent consisting of 1% isopropanol in hexane gave most favorable result, but the retention times were a little longer. It is evident that the resolution was also influenced by the structure of the solute. In all cases, the resolution of N-Ac-DL-Phe-OMe is lower than that of N-Ac-DL-Leu-OMe and N-Ac-DL-Val-OMe. Although the capacity factor of N-Ac-DL-Tyr-Ome varied greatly in different eluting systems, the separation factor and resolution were very close. It was observed that D-amino acid derivatives eluted faster than the corresponding L-isomers. In the above chromatographic conditions N-acetyl-DL-α-phenylethylamine could not be resolved.     

HORMONAL REGULATION OF CALLUS FORMATION IN RELATION TO NUCLEIC ACIDS AND AMINO ACIDS METABOLISM

The cotyledon segments of mung bean were cultured On Miller's medium with or without auxins and cytokinins. It was found that NAA and kinetiu were both required for callus formation and the growth rate increased proportionally to their concentrations. RNA and protein synthesis increased in the early stage of callus formation and the increase of the total RNA was mainly due to the increase of 25S and 18S RNA. In addition, it has been shown that the total amount of free amino acids in the control segments obviously increased after incubation and was larger than that in the callus-forming segments. On the other hand, the amount of protein amino acids in the callus-forming segments was larger than that in the control. Both proline and hydroxyproline existed in the control and callus-forming segments were increased, but the ratio of hydroxyprolinc and proline in the callus-forming segments was tfigher than that in the control.     

萘与丙烯在脱铝丝光沸石上的烷基化反应

Shape selective alkylation of polynuclear aromatics has begun to receive increasing attention. 2,6 dialkylnaphthalenes are important raw materials for manufacturing high quality polyester fibers and plastics. Understanding of the reaction and the catalysis for conversion of polycyclic aromatic hydrocarbons is needed both from fundamental and practical view points. In this paper, alkylation of naphthalene with propene over a series of dealuminated mordenite with different Si/Al ratios was carried out in an autoclave with an electromagnetical stirrer. Textural property of the dealuminated mordenite was determined by nitrogen adsorption. The amount of the acid sites was measured by NH 3 TPD. The catalytic activity of HM and β shape selectivity for products increased with increasing the Si/Al ratio in HM. Moreover, the selectivity for alkylation with propene was also increased by dealumination treatment. The increase of the catalytic activity was attributed to the formation of mesopores, which significantly promoted the diffusion of reactants and products in mordenite. It was suggested that the increase of β selectivity resulted from the elimination of acid sites from the external surface, and the selectivity for alkylation with propene was improved owing to the creation of the interconnection between 12 ring and 8 rimg channels by dealumination.     

Comparative study on the reaction of methane over a ZnO bed in the absence and presence of CO2

The reaction of zinc oxide with methane in the absence and presence of CO2 were theoretically and experimentally investigated using HSC Chemistry 5.1 software and a fixed bed reactor, respectively. In the absence of CO2 at 1193 K, the reduction of ZnO was accompanied with methane cracking, and metallic zinc, CO, and H2 were the main reaction products. This system could be utilized for the co-production of metallic zinc and synthesis gas, in which ZnO was a donor of oxygen. In the presence of CO2, ZnO plays as a catalyst in the CO2 reforming of methane and produces syngas with the average H2/CO ratio of 0.88 at 1193 K, which was close to the total reaction theoretic value of 1. It was also found that higher temperature favored high CH4 and CO2 conversions. XRD technique was used to characterize the ZnO species. The result showed that there were no differences in the peak profiles of the XRD patterns of the ZnO powder obtained before and after passing the CH4/CO2 mixed gases for 6 h at 1193 K. It is suggested that ZnO functions as a catalyst according to the redox cycle and metallic zinc plays the role of intermediate product in this process.     

Separation of Aniline Derivatives by Micellar Electrokinetic Capillary Chromatography

A micellar electrokinetic capillary chromatography (MECC) was developed for the determination of aniline and 6 substituted anilines. The seven components were separated within 25min in the buffer solution of 40mmol/L sodium borate and 100mmol/L SDS. It was found that the separation was dependent on operating voltage, pH value, borate and SDS concentrations.The analytical performance was examined in terms of linear response and reproducibility.Wastewater was determined by the established method.     

SINERING BEHAVIOUR OF RANEY-COPPER CATALYST IN VARIOUS ATMOSPHERES

Raney-Copper(R-Cu)catalyst was prepared and its sintering behaviour in atmospheresat teperature 300℃-600℃ was detected by methods of SSA,PSD,XRD and SEM.It was found thatsintering of R-Cu started from much lower temperature than the melting point of copper.Changesboth on the surface and in the body phase were discovered.There is a rule in the extent ofsintering for R-Cu in different atmospheres which is related to the adsorption of the particulargases molecules on the surface of the catalyst.Dynamical equations of the surface decrease isestablished and the mechanism of sintering is discussed.Calculations of quantum mechanics givethe similar results.     

银胶体系中的平衡因素对表面增强拉曼散射的影响

分析银胶体系中样品分子的平衡因子有器壁、银胶、水和杂质，并试验了某此样品的表面增强拉曼散射强度对这些因素的响应，指出全面分析影响对于表面增强拉曼散射的分应用的重要性。     

高血压性左室肥厚患者全血镁的测定

通过对比观察了50例高血压性左室肥厚患者和60例高血压性无左室肥厚患者全血镁含量的变化。结果表明,左室肥厚组全血镁明显低于无左室肥大组（P＜0．05）。提示高血压性左室肥厚患者镁的缺乏,可能是形成左室肥厚的因素之一。建议高血压性左室肥厚患者,在降压治疗过程中,同时给予适量补充镁剂,有利于左室肥厚的逆转。     

Load drop at the upper yield point of a polymer

The stress-system curves have been measured for isotropic and oriented specimens of poly(ethylene terephthalate) in extension, shear, and compression. It was found that for all these types of deformations there was an intrinsic yield drop, i.e., a fall in true stress. It is concluded therefore that the stress for initiation is greater than the stress for propagation of yielding.     

Extraction of Rare-Earth Elements in Hydrofluoride Decomposition of Loparite Concentrate

Distribution and existence forms of rare-earth elements in decomposition of the loparite concentrate with ammonium hydrofluoride were studied. It was found that, in the course of the aqueous leaching of the fluorinated concentrate, rare-earth elements fully remain in the insoluble residue as complex salts of general formula NaLnF₄. The process of pyrohydrolysis of the insoluble residue was examined. It was shown that varying the process conditions always results in that a NaLnF4-containing product is obtained. It was found that rare-earth elements can be extracted from the insoluble residue and separated from calcium and thorium, and the conditions for this extraction were determined.     

烷基膦酸单酯的合成

用烷基膦酸二酯催化水解合成了相应的酸性单酯。首次建立了用叔丁基氯制成的Grignard试剂与亚磷酸二酯反应、继而用Todd碱性氧化法合成高位阻叔丁基膦酸单酯的新的合成路线, 这一合成路线比用Clay反应、继而醇解和水解的方法得率高。     

连续样条小波变换用于分解重叠峰的研究

以B-样条小波为分析小波，提出了用于分析化学重叠信号解析的新方法——连续样条小波变换，结果表明：连续样条小波变换应用于分析化学信号的处理，能使峰变窄同时还能提高信号的信噪比，是一种新型有效的重叠信号解析方法，能从含噪声重叠信号中直接得到重叠峰的峰数目及其相应的峰位置。     

Kinetic determination of ruthenium using the oxidation of a macrocyclic complex of Nickel(II) by iodate

It was found that complex ruthenium and iridium sulfates catalyze the oxidation of macrocyclic nickel(II) complexes by iodate. Dependences of the reaction rate on the procedure of the preparation of the catalyst, concentrations of components, the acidity of the reaction mixture, and temperature were determined. Based on these studies, a procedure was developed for the determination of ruthenium compounds in solutions. It was demonstrated that this reaction can be used for the determination of iridium.     

Determination of trace amounts of rare earth elements by neutron activation analysis after preconcentration using hydrated magnesium oxide

A preconcentration method of 13 rare earth elements (REES) was studied for neutron activation ananlysis (NAA). Hydrated magnesium oxide was used as the preconcentration agent to absorb the REES ions from aqueous solution onto the solid magnesium oxide, which was separated and analyzed. It was observed that the Langmuir equation for isothermal adsorption was well obeyed by the REES under the condition studied. The efficiency of the preconcentration process using hydrated magnesium oxide was critically examined for each of REE and for mixture of REES by preparing a known volume of solution containing known amount of trace REES. NAA was used to analyze REES recovered by the preconcentration process. It was found that the REES recoveries were satisfactory and the preconcentration process is reliable. There are several resort resort areas in Taiwan where local people are enjoying its hot spring water. It is generally believed that the hot spring water spa would bring about some sorts of therapeutic functions. The preconcentration method developed above, was applied to analyze the trace amounts of REES in hot spring wate in Taiwan.     

多面体低聚八硝基苯基硅倍半氧烷纯度分析

使用高效液相色谱-电喷雾四级杆飞行时间质谱(HPLC-ESI-Q-TOF MS)联用技术对八硝基苯基硅倍半氧烷(ONPS)纯度进行分析, 从而判定ONPS产物峰及杂质峰的位置, 根据ONPS峰和杂质峰的面积比计算ONPS的纯度. 通过改变HPLC的洗脱梯度和测试时间, 将ONPS产物中的杂质峰完全分开, 测得硝基苯基硅倍半氧烷(NPS)质量分数为97.55%, 其中ONPS的纯度约为92.42%, 产物中含有九硝基八苯基硅倍半氧烷(9-NPS)约5.13%, 其它杂质含量约为2.45%. 通过对ONPS高效液相色谱图峰形和同分异构体极性情况分析, 进一步证明ONPS分子中硝基取代发生于对位和间位. 使用超高效液相色谱(UPLC)对ONPS进行分析, 以更高的分离效率验证了HPLC的结果. 该方法可作为ONPS纯度的分析方法.     

Determination of heavy metal concentration in feed and permeate streams of polymer enhanced ultrafiltration process

Polymer enhanced ultrafiltration (PEUF) is a newly developed method for the removal of heavy metals from aqueous solutions. This method was applied for the removal of mercury and cadmium with the presence of polyethyleneimine (PEI) as a water soluble polymer. After ultrafiltration experiments for metal–polymer mixtures, two separate streams, namely, retentate and permeate, former of which contains mainly metal–polymer complex and free polymer molecules while latter of which mainly contains free metal ions, were obtained. At the end of PEUF experiments, performance of operation was determined by concentration analyses which was achieved by atomic absorption spectroscopy (AAS) applied in a different way for permeate and retentate streams considering the effect of presence of polymer. For mercury analysis, cold vapor AAS was applied. It was observed that the presence of PEI did not affect the atomic absorption signal when 10% HCl was added to the sample solutions. For calcium and cadmium, flame AAS was used. It was observed that change in PEI concentration results in change in measured concentration of calcium and cadmium. Therefore, two new approaches were developed for accurate measurement of concentrations of calcium and cadmium. It was also observed that presence of other metals did not affect the accuracy of the measurement of a particular metal in the concentration range studied.