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     

光化学固定法表面改性医用高分子材料研究进展

综述了光化学固定法表面改性医用高分子材料方面的研究进展,介绍了光化学固定法的原理和优点。     

活性污泥吸附重金属离子的研究进展

从处理含重金属离子废水的现状出发,简述了活性污泥吸附重金属离子过程中的表面有机络合、离子交换及其它机理;讨论了温度、时间、pH值、污泥种类、预处理、重金属离子浓度等因素对活性污泥吸附重金属离子的影响,并对解吸方式进行了论述;综述了目前国内外有关活性污泥吸附重金属离子的最新研究成果,指明了进一步加强吸附机理和固定化技术以提高活性污泥应用性的研究是今后的方向。     

Transformations and losses of fertilizer nitrogen on no-till and conventional till soils

A field study was conducted in 1982 to measure the effect of no-till (NT) and conventional till (CT) systems on N transformation after surface and subsurface applications of N fertilizers. Urea, urea-ammonium nitrate (UAN) solution, (NH₄)₂SO₄ (AS), and CA(NO₃)₂ were applied to NT and CT plots (5.95 m²) at a rate of 448 kg N ha^–1. A comparison of fertilizer N recovered in soils receiving incorporated or surface applied N was used to estimate NH₃ volatilization while denitrification was estimated from fertilizer N recovered in the presence and absence of nitrapyrin with incorporated N. Immobilization was assessed in microplots (0.37 m²) after surface application of (¹⁵NH₄)₂SO₄ to NT and CT systems at a rate of 220 kg N ha^–1.The results indicate little difference between NT and CT systems on urea hydrolysis rates and immobilization of surface applied fertilizer N. Approximately 50% and 10% of the surface applied N was recovered in the inorganic and organic fractions, respectively, on both tillage systems. The N not recovered was likely lost from plot areas through soil runoff. Incorporation of UAN, urea and AS resulted in 20 to 40% greater inorganic N recovery than from surface application. Nitrification rates were greater under the NT than the CT system. The similarities in concentration in the various N pools observed between the two tillage systems may be partially due to the short length of time that NT was imposed in this field study (<1 year) since other researchers using established tillage systems (>5 y) indicate that NT tends to promote decreased efficiency of fertilizer N.     

Lipase PS-catalyzed transesterification of citronellyl butyrate and geranyl caproate: Effect of reaction parameters

Pseudomonas sp. lipase PS was immobilized by adsorption and tested for its ability to catalyze the synthesis of citronellyl butyrate and geranyl caproate by transesterification in n-hexane. The reaction parameters investigated were: enzyme load, effect of substrate concentration, added water, temperature, time course, organic solvent, pH memory, and enzyme reuse. Yields as high as 96 and 99% were obtained for citronellyl butyrate and geranyl caproate, respectively, with 300 units (approx. 15% w/w of reactants) of lipase PS. Increasing amounts of terpene alcohol inhibited lipase activity, while excess acyl donor (triacylglycerol) concentration enhanced ester production. Optimal yields were obtained at temperatures from 30–50°C after 24-h incubation time. Yields of 90 and 99% were obtained for citronellyl and geranyl esters, respectively, with 2% added water. Solvents with log P values ≥ 2.5 showed the highest conversion yields. pH 7 and 6–8 seemed to be ideal for citronellyl butyrate and geraniol caproate, respectively. The lipase remained active after reusing 12 times.     

炭纤维载体表面快速固着机理研究

采用炭纤维作为生物膜载体材料进行了污水处理实验,对炭纤维载体表面快速固着机理进行了研究。研究发现,炭纤维能够在水中快速且大量的固着活性污泥微生物。采用表面积测定仪、扫描电镜和XPS研究了炭纤维的表面特征。结果显示,炭纤维的表面形貌、表面官能团及表面活性碳原子是影响炭纤维表面微生物快速且大量固着的主要因素。     

载体化双邻香草醛类苯亚胺钛四齿配体催化剂的制备及其催化性能

以邻香草醛和4,4＇-二氨基二苯醚为原料合成的双邻香草醛（二苯醚）苯亚胺配体与四氯化钛反应制备双邻香草醛（二苯醚）苯亚胺钛络合物,并以SiO2-PEG复合物为载体制备载体化新型四齿配体烯烃聚合催化剂,考察PEG改性对SiO2的影响及载体催化剂的聚合性能．结果表明,改性后可将PEG链接到SiO2载体表面;在50℃、Al／Ti摩尔比为1500时,催化剂活性最高,达到3．21×10^5g／（mol·h）,Al／Ti摩尔比为1000时,聚合物相对分子质量达到最大值4．01×10^5．     

Reducing N losses (NH3, N2o, N2) and immobilization from slurry through optimized application techniques

In model, pot and field trials the effect of C reduced slurries and different application techniques on N losses and N immobilization were investigated. The C reduced slurries were produced by mechanical separation. Ammonia losses from surface-applied and injected cattle slurry were measured under field conditions using a wind tunnel system. Injection of slurry was the most efficient way to reduce volatilization of ammonia. After 6 days the total loss from the injected slurry was only 9% of that from surface band application. Furthermore, additional losses of N may occur through denitrification, specially after injection of slurry which may create an anaerobic environment abundant in readily oxidizable C. Therefore denitrification measurements by the acetylene inhibition technique were conducted. Until 100 days after application the loss from the injected slurry was 7.3 kg compared to 4.5 kg N ha^–1 from surface band applied slurry. After injection, denitrification was only 4.1 kg N ha^–1 for C reduced compared to 6.5 kg N ha^–1 for normal slurry. In pot trials the ammonium-¹⁵N of normal slurry and C-reduced slurry was utilized by oats between 52 and 60%, the ammonium sulfate by 67%. The increased biomass C confirmed a greater immobilization of the NH₄-N of the normal slurry resulting in a lower initial efficiency.Dedicated to Prof. Dr. A. Amberger on his 75th birthday     

海藻酸钠-硅藻土包埋石油脱硫菌Rhodococcus sp.H-412

生物菌固定化研究对生物脱硫技术的推广应用具有重要的意义。本文以实验室筛选的、符合4S脱硫代谢途径的Rhodococcus sp．H．412为研究对象，二苯并噻吩（DBT）为生物催化脱硫模拟化舍物，考察了脱硫菌Rhodococcus sp．H．412的固定化操作条件和使用条件。试验结果表明：在交联温度为4℃，交联剂氯化钙溶液浓度为0．10mmol／L，海藻酸钠质量分数为3．0％，添加剂硅藻土质量分数为1．0％，菌胶比（菌体湿重：胶体体积）为1：20的条件下，用8号医用针头造粒，可以得到具有较高的脱硫活性、较好的机械强度和传质性能的固定化细胞颗粒。固定化细胞相对游离细菌而言，具有较高的温度适应能力和较宽的pH适应范围。