钌钯双金属催化剂固载顺序控制及性能

以Al_2O_3、PdCl_2和RuCl_3为原料,采用水溶液浸渍法,通过控制固载顺序、制备流程以及焙烧温度等条件,制得系列负载型Ru Pd双金属催化剂,并用于对苯二甲酸二甲酯(DMT)制取1,4-环己烷二甲酸二甲酯(DMCD)的选择性加氢过程。其中,Ru和Pd的总负载量为0.3%(以催化剂总质量为基准,下同),且m(Ru)∶m(Pd)=1∶1。结果发现,采用先Ru后Pd(Ru-Pd)式固载顺序和浸渍-干燥-浸渍-干燥-焙烧(IDIDC)型制备流程,并在450℃下焙烧后,所得负载型Ru-Pd双金属催化剂的反应性能最佳,在6 MPa、180℃下,DMT转化率为89.6%,DMCD选择性为96.0%,DMCD产率为85.9%。这可能与Ru-Pd中大粒径粒子的形成受到抑制、粒径尺寸和分布更小、比表面积和总孔容更高、表面Pd原子摩尔分数较高以及Ru/Pd物质的量比较低有关。     

聚氨酯泡沫固定化重组枯草杆菌三段培养生产青霉素酰化酶

引　言青霉素G酰化酶 (penicillinGacylase ,EC3 5 1 11,PGA)是 β 内酰胺类抗生素工业中的关键酶之一 .目前主要采用大肠杆菌和巨大芽孢杆菌进行工业化生产 ,但由于产酶水平较低、变温发酵和需要苯乙酸诱导等缺点 ,国内外研究者尝试采用各种基因重组技术 ,以期大幅度提高产酶     

Poly(pyridine-2,5-diyl)–CuCl2 catalyst for synthesis of dimethyl carbonate by oxidative carbonylation of methanol: catalytic activity and corrosion influence

A -conjugated polymer, poly(pyridine-2,5-diyl) (PPy) was investigated as a support for CuCl₂ in the synthesis of dimethyl carbonate by oxidative carbonylation of methanol. The PPy–CuCl₂ adduct had high catalytic activity which was comparable to that of the homogeneous CuCl₂ catalyst. The adduct caused corrosion of stainless-steel vessels only to minor extent, compared with the homogeneous CuCl₂ catalyst. This PPy–CuCl₂ catalyst was easily recycled by filtration and showed a similar catalytic activity in the third time use. The presence of the -conjugated system in PPy, through which electrons can move, may bring about the high catalytic activity for the oxidative carbonylation of methanol, which involves Cu(II)/Cu(I) redox processes.     

Immobilization of a cyclodextrin glucanotransferase (CGTase) onto polyethylene film with a carboxylic acid group and production of cyclodextrins from corn starch using CGTase‐immobilized PE film

Carboxylic acid groups were introduced onto polyethylene (PE) film by radiation‐induced graft copolymerization. Subsequently, the clodextrin glucanotransferase (CGTase) was immobilized on the PE film with a carboxylic acid group. The activity of the immobilized CGTase on PE film was in the range of 0.40–1.04 U/cm² per min. The production of cyclodextrins (CDs) from corn starch was examined using the CGTase‐immobilized PE film. The production ratios of CDs using CGTase‐immobilized PE film was in the following order: α–CD > β–CD > γ–CD. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2451–2457, 2002     

SHS of mineral-like ceramics for immobilization of radioactive nuclear wastes

Synthetic analogs of titanate ceramics (perovskite and zirconolite) designed for use as a matrix for immobilization of high-level nuclear fuel reprocessing wastes (HLW). Such ceramics have been prepared by SHS method from a mixture of titanate ceramics and non-radioactive model oxides. Synthesis conditions have been optimized. The synthesized low-porosity cylindrical compacts exhibited a high strength and low rate for leaching Cs, Sr, Y, Ce, and La in bidistilled water. The phase composition and microstructure of synthesized products have been characterized. The immobilization of Cs was found to be accompanied by a marked loss of this element. The text was submitted by the authors in English.     

细胞固定化催化生产精细化学品的研究进展Q

摘要：细胞固定化技术具有流程简单、生物相容、操作稳定等优点，可有效保证细胞活性，实现高效的细胞催化生产精细化学品。本文介绍了表面附着、凝胶包埋、聚电解质层层自组装膜等多细胞固定化方法，及其在二元醇、生物乙醇、乳酸、酯、多糖等精细化学品生产中的研究现状和进展，并分析讨论了各种方法存在的问题。同时，总结了近年来新发展的单细胞纳米涂层固定化方法的机理、趋势及应用于精细化学品生产的可能性。最后对细胞固定化催化生产精细化学品面临的技术挑战及研究方向做出展望，以期为精细化学品生产提供一定的技术支持。     

Simulation of the nitrogen balance in the soil and a winter wheat crop

A simulation model for winter wheat growth, crop nitrogen dynamics and soil nitrogen supply was tested against experimental data. When simulations of dry matter production agreed with measurements, nitrogen uptake was simulated accurately. The total amount of soil mineral nitrogen as well as the distribution of mineral nitrogen over the various soil layers were generally simulated well, except for experiments in which fertilizer was applied late in spring. In these experiments, applied nitrogen disappeared because it could not be accounted for by the model. Some explanations for this disappearance are briefly discussed.     

Immobilization of biologically active species on PA‐6 foils treated by a dielectric barrier discharge

In the field of biomaterials and biomedical devices, surface activation has been focused on creating functional groups capable of preferential adsorption of biologically active species (proteins, enzymes, cells, drugs, etc.). In this way an interface can be created between the synthetic material and the biological medium, with the aim of increasing the compatibility of the implant with the human organism. In our experiments a dielectric barrier discharge (DBD), in helium at atmospheric pressure, was used as the source of energy capable of creating active centers that render the functionalized surface favorable to immobilization of biological molecules. Retention of immunoglobulin (IgG) and heparin biomolecules on polyamide‐6 (PA‐6) surfaces after treatment by the DBD was analyzed by atomic force microscopy, adhesion evaluation, and measurement of the contact angle titration in order to assess this incorporation on the treated surfaces. The marked adsorption of the biomolecules on the active sites created by DBD on the exposed surfaces also was related to a complex set of processes, such as enhanced roughness, increased surface wettability, and modified distribution of cationic and anionic groups on the treated surfaces. All these factors could promote interfacial interactions between the specific groups of the biomolecules existing in the biological medium and the type of cationic and/or anionic groups present on the surface. The efficiency of the DBD treatment showed that the DBD technique is useful for preactivation of the polymer surface for immobilization of other biologically active species (such as drugs and enzymes). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1985–1990, 2003     

An easy pot incubation method for measuring nitrogen mineralization from easily decomposable organic material under well defined conditions

A pot incubation method for measuring mineralization dynamics from fresh plant material was tested. The aim was to develop a method which under well-defined conditions could produce mineralization data suited for estimating model input parameters for nitrogen prediction models. The results showed that the water tension of the soil could be controlled easily and precisely by diffusion through porous ceramic cups, and that nitrogen mineralization or immobilization could be measured already after 15 days at 15°C. The results showed that for the incubated catch crop residues carbon, nitrogen and nitrate-N contents were the most important factors determining mineralization. No significant effects ould be ascribed to other parameters measured.     

Thermal crosslinking of collagen immobilized on poly(acrylic acid) grafted poly(ethylene terephthalate) films

Graft polymerization of acrylic acid onto plasma‐treated poly(ethylene terephthalate) (PET) films was used to prepare surfaces suitable for collagen immobilization by dip‐coating. Such surfaces could be used as matrices for smooth muscle cell cultures in tissue engineering. Contact angle measurements showed that plasma‐treated and grafted PET films undergo considerable surface reorganization during storage under ambient conditions. However, after collagen immobilization the contact angle remained relatively stable. The amount of collagen initially attached to the film surface increased with increasing poly(acrylic acid) graft density, but subsequent washing in water led to significant collagen loss. This loss could nevertheless be substantially reduced by thermal crosslinking of the collagen in the range 110–130 °C. Atomic force microscopy (AFM) observations suggested that the washed crosslinked collagen has a very similar structure to that of the un‐crosslinked collagen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1874–1880, 2002