壳聚糖氧化自组装膜的制备及其性能

由高碘酸钠和壳聚糖溶液反应,成功制备出壳聚糖氧化自组装膜。采用傅立叶变换红外光谱(FTIR)和X射线衍射法对氧化自组装膜进行了结构表征,并对膜的吸水率及其力学性能进行了测试。当壳聚糖为3 g,而高碘酸钠加入量等于0.010 g时,得到壳聚糖氧化自组装膜的最佳的抗张强度,干膜为54.32 MPa,湿膜为29.11 MPa,相对壳聚糖膜分别提高了17.52%和26.78%;并且得到了最佳的阻水性,其吸水率为78.51%,相对于壳聚糖膜降低了6.88%。     

Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: propanol as background electrolyte solvent

Peak dispersion effects in nonaqueous capillary electrophoretic separations of aromatic anionic analytes were investigated in a propanolic background electrolyte solution. Poly(glycidylmethacrylate-co-N-vinylpyrrolidone) coating was applied to the capillary to suppress the electroosmotic flow and to improve the repeatability of the migration times. Electrical field strengths up to 2000 Vcm(-1) were applied in separations and the separation efficiencies were compared with theoretical values calculated on the basis of plate height theory. The contributions to the total plate height were calculated for injection plug length, diffusion, Joule heating, electromigration dispersion, analyte adsorption to the capillary wall, and detector slit aperture length. Analyte diffusion coefficients were measured by Taylor dispersion method, while distribution constants were measured chromatographically. Agreement between the calculated and empirical results was fairly good even though some approximations were required. In most cases the longitudinal diffusion contribution governed the total plate height, while the contribution of Joule heating was insignificant even at exceptionally high field strengths used. The relatively long detection slit aperture was found to influence the separation efficiency strongly, while the other dispersion sources that were investigated were of minor importance, except for adsorption in the case of one analyte. With all analytes, the dispersive effect of longitudinal diffusion was reduced as the field strength was increased, leading to enhanced migration velocities and faster separations.     

反相非水乳液法制备聚酰亚胺微球

在N,N-二甲基甲酰胺(DMF)/Pluronic-F127、十二烷基苯磺酸钠(SDBS)/液体石蜡(LP)反相非水乳液体系中,以均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为单体合成聚酰胺酸(PAA),采用吡啶/乙酸酐脱水剂,对PAA化学酰亚胺化,并进一步热酰亚胺化,制得PI耐热微球.产物通过红外、热重、扫描电镜表征.结果表明,较高的固含量和良好的乳液分散性有利于PI微球的形成;反相非水乳液体系稳定的配比条件是,VDMF∶VLP为1∶4,MF127∶MSDBS为3:2,乳化剂用量为9 wt%;在此配比条件下,当固含量为20%,热酰亚胺化温度不高于330℃时,可制得分散良好、球形规整、高热稳定性的PI微球,其粒径约为10μm.     

Thermal characterization of a Spanish red mud

A Spanish red mud was thermally characterized. Chemical and mineralogical composition were determined by XRF and XRD.The thermal events observed in the range from room temperature to 1300°C were related to the sample composition. The first mass loss step was related to free water content, while many of the other processes were related to dehydration processes. It was found that most of the decomposition reactions of hydrohematite, ferrihydrite, aluminogoethite, boehmite, silicates and carbonates were strongly overlapping. It was also explained the formation of silicates and calcium titanate, which presence was confirmed at 1000°C by XRD.     

碘酸钾滴定法测定分银渣中的锡含量

采用碘酸钾滴定法测定分银渣中的锡含量。试样用过氧化钠熔融,水浸酸化,加铁粉过滤除杂质;加铝片还原,待反应平静后加热煮沸至冒大泡,冷却至室温;以淀粉为指示剂,碘酸钾滴定至淡蓝色为终点。对试样进行11次平行测定,相对标准偏差(RSD)小于1.2%,加标回收率在99%~101%。方法流程短,除杂质效果好,结果准确。     

酚醛树脂胶粘剂的复合改性

采用有机硅和蔗糖对酚醛树脂胶粘剂进行复合改性,以提高树脂胶膜的柔韧性,并使产品具有较高的粘接强度。通过考察改性剂有机硅种类、改性剂加入时间、加入量对产品性能的影响,结果发现:在反应开始时加入总质量1.5%的有机硅(8427)和总质量0.9%的蔗糖,反应所得产品分子量及粘度适中,粘接强度高达6MPa,游离甲醛含量低至0.067%。采用FT-IR和TG对产品结构及性能进行分析,由此可知,改性后的酚醛树脂胶粘剂有大量—Si—O—生成,其柔韧性和耐热性有很大的提高。     

THE PREPARATION AND STUDY ON THE NANO-TiO2/SILK FIBROIN COMPOSITE FILMS BY THE SOL-GEL METHOD

Based on the sol-gel technique using butyl titanate as oxide precursor, the regenerated SF (silk fibroin)/nano-TiO2 composite films were synthesized. Different amounts of butyl titanate to SF were used to verify this effect on the characteristics of the formed materials. Samples were characterized by thermogravimetric analysis, X-ray diffractometry, UV, AFM and FT-IR spectroscopy.The experimental results reveal that, compared to the pure silk fibroin films, the mechanical strength of these regenerated SF/nano-TiO2 composite films were increased and the dissolubility in water of SF/nano-TiO2 composite films in aqueous solution were decreased. The diameter of nano-TiO2 particle films was about 80nm through UV and AFM. The nano-TiO2 particles were well dispersed in the regenerated silk fibroin. It was found that the crystal structures of the composite films were transited from typical Silk Ⅰ to typical Silk Ⅱ by the XRD and FTIR. Furthermore, the crystallinity of the composite films was obviously improved. Through the TGA, it was demonstrated that the heat transition temperature of composite films was also enhanced.     

Preparation of186Re labeled immunoglobulins: Direct and indirect methods

Kits were developed for labeling sulphur microcolloids with^99mTc. The microcolloids were prepared to get the desired particle size. The stannous chloride was treated with sulphide ions released from thioacetamide in the presence of carboxymethyl cellulose and the pH of the reaction was adjusted to 3.0. The contents of single reaction vial were reacted with^99mTc, the radiochemical yield was higher than 95%. Sulphur-microcolloid kits were stable and the stability was followed for 6 hours. The freeze-dried kits were followed more than three months after production and were found stable. Bone marrow uptake in rabbits was determined to be about 36%. The preparation of^99mTc-sulphur microcolloid is performed in single step process and axellent node scintigraphy was obtained using experimental animal.     

沉淀剂用量对反萃取产物结构、形貌及热分析结果的影响

研究了相同浓度不同用量的沉淀剂草酸从负载铈的有机相中反萃取沉淀。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、红外分析(FTIR)及热重-差热分析仪(TG-DSC)等手段,对反萃所得铈沉淀产物的物相、形貌、红外谱图和热失重等进行了分析。结果表明:随着沉淀剂草酸用量从90%增大到150%,萃取产物的晶型逐渐完整,但只有草酸用量为130%时,沉淀产物呈现为典型的水合草酸铈,其他沉淀剂用量经验证均未得到确定的化合物;草酸用量从90%增大到150%时产物的形貌从不规则的块状逐渐变为较为均匀的片状,且草酸用量越大,片状产物的尺度越大;热重分析表明萃合物的失重率较大,考虑是萃合物中含有大量的有机物所致。     

基于氧化石墨烯气凝胶固相萃取柱检测有机磷农药北大核心CSCD

以氧化石墨烯气凝胶三维纳米材料作为固相萃取的吸附剂,结合高效液相色谱,对食品中的有机磷农药(辛硫磷、双硫磷、倍硫磷、杀螟硫磷)进行检测分析。首先,利用冷冻干燥的方式制备得到氧化石墨烯气凝胶,通过扫描电镜、红外光谱、比表面积吸附等一系列的实验手段对其形貌及物理特性进行了表征,证明其成功合成。从扫描电镜中可见石墨烯的层状褶皱结构,其表面积为740.51 m^(2)/g。然后,将氧化石墨烯气凝胶直接填充于固相萃取柱中,在未借助任何硅胶等基体的条件下进行萃取研究;通过单因素实验,系统研究了萃取和洗脱条件对有机磷农药萃取回收率的影响。结果显示,在上样体积15 mL、样品溶液pH值4、上样速率1.0 mL/min、洗脱剂1.0 mL乙腈的条件下萃取回收率最高。与商用的萃取材料进行比较,包括碳十八硅胶柱(C18)、阴离子交换柱(SAX)、氨基柱(-NH_(2))和硅酸镁柱(Florisil),氧化石墨烯气凝胶填充的固相萃取柱的萃取回收率有明显提高。实验考察了氧化石墨烯气凝胶直接填充的萃取柱的寿命,结果显示该萃取柱可以重复使用15次,可见解决了分散无基体支撑的石墨烯纳米片容易破碎、堵塞筛板的问题。与液相色谱联用建立分析方法,4种有机磷农药的线性范围较宽,辛硫磷、双硫磷和倍硫磷的线性范围为1~200μg/L,杀螟硫磷的线性范围为2~200μg/L,线性拟合良好(线性相关系数r^(2)≥0.9949),检出限为0.2~0.5μg/L,满足于我国和其他国家限定标准的检测。将该方法应用于实际样品,在苹果皮中未检测到有机磷农药,对其进行加标,回收率为70.5%~93.6%,相对标准偏差≤10.4%。     

Evaluation of on-line solid phase extraction-capillary electrophoresis-electrospray-mass spectrometry for the analysis of neuropeptides in human plasma

In this study, the suitability of SPE coupled on-line to CE-electrospray-MS (SPE-CE-ESI-MS) was evaluated for the analysis of neuropeptides in human plasma. First, CE-ESI-MS was investigated and a sample pretreatment based on precipitation with ACN was used for cleanup of plasma samples. The main quality parameters were determined and were consistent with those previously obtained for the analysis of standard mixtures, e.g., the LODs were of around 1 microg/mL. SPE-CE-ESI-MS employing microcartridges containing a C18 stationary phase was explored in order to decrease the LODs. A double-step sample cleanup pretreatment consisting of precipitation with ACN and ultrafiltration through 3000 Da MW cut-off membranes was needed to prevent the microcartridge saturation. Repeatability, reproducibility, linearity, and LODs of the SPE-CE-ESI-MS method and the durability of the microcartridges were studied. The LODs were markedly improved, ranging between 10 and 0.1 ng/mL depending on the peptide.     

Kinetics and Characterization of Degradation Products of Dihydralazine and Hydrochlorothiazide in Binary Mixture by HPLC-UV,LC-DAD and LC–MS Methods

Dihydralazine and hydrochlorothiazide were stored at high temperature and humidity, under UV/Vis light and different pH, as individual drugs and the mixture. Then, a sensitive and selective HPLC-UV method was developed for simultaneous determination of dihydralazine and hydrochlorothiazide in presence of their degradation products. Finally, the degradation products were characterized through LC-DAD and LC–MS methods. Dihydralazine was sensitive to high temperature and humidity, UV/Vis light and pH?≥?7. At the same time, it was resistant to acidic conditions. Hydrochlorothiazide was sensitive to high temperature and humidity, UV/Vis light and changes in pH. Its highest level of degradation was observed in 1 M HCl. Degradation of the drugs was higher when they were stressed in the mixture. In the case of dihydralazine, the percentage degradation was 5–15 times higher. What is more, dihydralazine became sensitive to acidic conditions. Hydrochlorothiazide was shown to be more sensitive to UV/Vis light and pH?>?4. Degradation of dihydralazine and hydrochlorothiazide followed first-order kinetics. The quickest degradation of dihydralazine was found to be in 1 M NaOH while of hydrochlorothiazide was in 1 M HCl (individual hydrochlorothiazide) or at pH 7–10 (hydrochlorothiazide in the mixture). A number of new degradation products were detected and some of them were identified by our LC-DAD and LC–MS methods. In the stressed individual samples, (phenylmethyl)hydrazine and 1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide were observed for the first time. Interactions between dihydralazine and hydrochlorothiazide in the mixture were confirmed by additional degradation products, e.g., 2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1,4-trioxide.     

Cr改性USY分子筛提高裂化催化剂的异构化性能

在催化裂化过程中,烷烃分子在酸性催化剂表面进行一系列的反应,其中氢转移反应能导致汽油中的烯烃质量分数降低,而异构化、环化、芳构化反应则改善裂化产品的分布,对提高裂化汽油的辛烷值有明显的效果。为了解决我国裂化汽油中烯烃质量分数过高的问题,目前大多数催化裂化装置都采用了降烯烃裂化催化剂,以氢转移反应活性高的REUSY分子筛作为裂化催化剂的活性组分。但由于REUSY分子筛的异构化活性较低,因此裂化汽油的辛烷值有所下降,需要对裂化汽油进行加氢异构化处理。若直接对裂化催化剂进行改性,提高其异构化反应活性,     

Optimisation of the chlorthalidone chiral separation by capillary electrochromatography using an achiral stationary phase and cyclodextrin in the mobile phase

The separation of chlorthalidone enantiomers in capillary electrochromatography on an achiral stationary phase when adding a chiral selector, hydroxypropyl-β-cyclodextrin, to the mobile phase, was optimised. The goal was to investigate the feasibility of modelling retention times and resolution when during the optimisation procedure regular replacement of columns is required due to their fragility. Therefore, it is essential that the packing procedure delivers reproducible columns. The optimisation of an existing chlorthalidone separation was chosen as case study. The influence of two factors, chiral selector concentration and organic modifier content, on the responses was modelled. The experiments performed prior to modelling were defined by a central composite design. Results on different columns, obtained under identical experimental conditions, were found comparable and thus modelling was possible in situations where several columns were required to complete a design. A second-order polynomial model was built for both responses. Optimal separations were also predicted using Derringer’s desirability functions. The optimum was found at 33 mM cyclodextrin and 16% (v/v) acetonitrile on two types of columns (with different packing times) leading to a strong reduction in analysis time for an equally good separation compared to the initial conditions. Measured and predicted responses were found comparable, indicating that acceptable models were obtained.     

Ionic effect on the binding of bilirubin to the imprinted poly(methacrylic acid-co-ethylene glycol dimethylacrylate)

A molecularly imprinted polymer (MIP) capable of detecting bilirubin was successfully synthesized. Bilirubin template was imprinted in poly(methacrylic acid-co-ethylene glycol dimethylacrylate) [poly(MAA-co-EGDMA)]. MAA and EGDMA were used as the monomer and the cross-linker, respectively. The optimal solvent conditions to maintain its stability were discussed. Solvent system based on ethylenediamine tetraacetic acid (EDTA) and ascorbic acid was compared with respect to the stability of bilirubin. pH and bilirubin concentration were both investigated for the bilirubin stability. Blue light as well as aeration was applied to inspect the regarding effects. The cross-linking effect was further confirmed by the thermogravimetric analysis (TGA). The effect of salts, such as NaCl and KCl on the binding capacity of the molecularly imprinted polymer was also discussed. Further, the rat serum and bile samples were applied and the binding of the MIPs for bilirubin was thus confirmed.     

Investigation of Artefact Formation During Analysis of Volatile Sulphur Compounds Using Solid Phase Microextraction (SPME)

The occurrence and origin of artefact formation during the analysis of volatile sulphur compounds in air by PDMS/Carboxen fibre were investigated. Among the studied compounds (hydrogen sulphide, carbon disulphide, diethyl sulphide, methyl ethyl sulphide, isopropanethiol, methanethiol, dimethyl sulphide, dimethyl disulphide, carbonyl sulphide), essentially mercaptans were shown to react to form the corresponding dimers. However, in the presence of several oxygenated and amines compounds which are common components of industrial effluents, no further artefact formation or reaction was noticed. Artefact formation was therefore considered to be independent of the sample matrix. Thermal oxidation occurring during the desorption step in the GC injection port was assessed. As metallic elements were previously suspected to catalyse the reaction, a specially deactivated SPME needle was tested, but no significant difference was noticed compared to the original needle. It was therefore assumed that metallic elements naturally present on Carboxen may act as catalysts. Similar results were obtained by using Carboxen in adsorbent tubes, as artefacts were increased by comparison with Tenax TA and molecular sieve 5A.     

THE PREPARATION AND STUDY ON THE NANO-TiO_2/SILK FIBROIN COMPOSITE FILMS BY THE SOL-GEL METHOD

1. INTRODUCTIONSilk is a well described natural fiber produced by the silkworm, B. mori, which has been used traditionally in the form of thread in textiles for thousands of years. This silk contains a fibrous protein that forms the thread core and glueli…     

固相萃取法分析水生生物体中17种酞酸酯类环境激素

水生生物样品去壳、搅碎、匀浆;干货样品则首先烘干、研磨和过筛。以丙酮作为提取剂超声波辅助提取3次,提取液经无水硫酸钠脱水后进行氮吹浓缩;浓缩液经处理过的Florisil硅藻土吸附柱净化和乙酸乙酯/己烷(1/5,V/V)洗脱剂洗脱与浓缩后,采用气相色谱-电子轰击电离源/质谱法进行定性分析与内标法定量分析。实验优化与选择了提取剂的种类、吸附剂的种类及其活化条件、洗脱剂的种类等样品前处理过程,并讨论了分析空白值的控制问题。分析方法的线性相关系数均大于0.99987,方法检出限均小于3.67μg/L,平均加标回收率为64.1%~124%,方法的相对标准偏差均小于16.4%。此分析方法成功地应用于3种鱼类(刀鱼、黑鱼、草鱼)、2种贝类(沙螺、牡蛎)、1种甲壳类(明虾)、1种头足类(章鱼)、2种植物(海带、海藻)和2种干货(干海带、丁香鱼干)样品中17种酞酸酯类环境激素含量的同时分析,所分析的样品都检测到邻苯二甲酸二甲酯、邻苯二甲酸二异丁基酯和邻苯二甲酸二丁酯,在大部分样品中还检测出邻苯二甲酸二乙酯和邻苯二甲酸二乙基己基酯,说明此5种酞酸酯已造成了一定程度的水体污染。     

水相中酵母细胞催化4-氯乙酰乙酸乙酯不对称还原反应

 利用活性酵母细胞催化4-氯乙酰乙酸乙酯(COBE)的不对称还原可以直接合成具有光学活性的4-氯-3-羟基丁酸乙酯(CHBE). 实验发现,在水相体系中主要生成D-(S)-型产物,COBE的转化率及CHBE的收率和光学选择性都比较高. 考察了底物和产物的浓度、辅助底物的种类和浓度、体系的pH和温度以及菌体培养条件等因素对反应的影响. 结果表明,在较低COBE浓度下R型产物占优,在高浓度下主要是S型产物; 较高的反应温度有利于S型产物的生成,pH≈8.0时可获得较高的S型产物选择性; 产物CHBE对COBE的还原反应具有一定的抑制作用. 在酵母催化COBE还原的同时需要一定的辅助底物来再生辅酶NAD(P)H,利用乙醇、异丙醇和仲丁醇作辅助底物可获得较高的立体选择性. 对数生长期和厌氧条件培养的细胞对生成S型产物较有利.