水洗钽粉中氮的测定

针对水洗钽粉中杂质元素的干扰,采用EMGA-620W氧氮分析仪,测定了水洗钽粉中的氮,并与脉冲气相色谱法测氧氮(联测)进行了比较,认为该法快速、准确、可靠。     

Simulation of nitrogen dynamics and biomass production in winter wheat using the Danish simulation model DAISY

A dynamic simulation model for the soil plant system is described. The model includes a number of main modules, viz., a hydrological model including a submodel for soil water dynamics, a soil temperature model, a soil nitrogen model including a submodel for soil organic matter dynamics, and a crop model including a submodel for nitrogen uptake. The soil part of the model has a one-dimensional vertical structure. The soil profile is divided into layers on the basis of physical and chemical soil characteristics. The simulation model was used to simulate soil nitrogen dynamics and biomass production in winter wheat grown at two locations at various levels of nitrogen fertilization. The simulated results were compared to experimental data including concentration of inorganic nitrogen in soil, crop yield, and nitrogen accumulated in the aboveground part of the crop. Based on this validation it is concluded that the overall performance of the model is satisfactory although some minor adjustments of the model may prove to be necessary.     

Evaluation of oxidative stability of canola oils by headspace analysis

Lipid oxidation is a major factor affecting flavor quality and shelf life of vegetable oils. Oxidative stability is therefore an important criterion by which oils are judged for usefulness in various food applications. In this study a method based on headspace analysis was developed to evaluate relative oxidative stability of canola oils. The method does not require the use of chemicals, involves minimal sample preparation, and can be performed on a relatively small sample size in comparison with traditional wet chemical methods. Canola oils freshly extracted in the laboratory from different seed samples were subjected to accelerated oxidation and analyzed for PV by standard methods and headspace volatiles by solid phase microextraction/GC-MS. Forward stepwise regression analysis of the data revealed a relationship between PV and headspace concentration of the volatile lipid oxidation products hexanal and trans,trans-2,4-heptadienal. The PV calculated using this formula correlated (R ²=0.73) with those measured by conventional methods. Presented in part at the 96th Annual Meeting of the AOCS, 1–4 May 2005, Salt Lake City, UT.     

影响PET树脂反应活性因素的分析

探讨了影响连续固相增粘产品活性的因素，提出了控制主反应器的温度、氮气流量、基础切片的端羧基、氮气露点等主要因素，实现生产的平稳控制，从而保证产品黏度的稳定。     

纤维增强塑料筋的性能与发展

本文详细介绍了纤维增强塑料筋（Fiber Reinforced Plastic Rebar，简称FRP筋）在国内外的发展概况及其基本物理力学性能，指出了目前的纤维增强塑料筋及其混凝土构件力学性能研究中存在的问题。     

Biosynthesis and identification of volatiles released by the myxobacterium Stigmatella aurantiaca

The volatiles released by agar plate cultures of two strains of the myxobacterium Stigmatella aurantiaca (strains Sg a15 and DW4/3-1) were collected in a closed-loop stripping apparatus (CLSA) and analyzed by GC-MS. Large numbers of substances from different compound classes (ketones, esters, lactones, terpenes, and sulfur and nitrogen compounds) were identified; several of them are reported from natural sources for the first time. The volatiles 2-methyltridecan-4-one (17), its isomer 3-methyltridecan-4-one (20), and the higher homologue 2-methyltetradecan-4-one (18) were identified in the extracts of both strains and were synthesized. In addition, strain Sg a15 produced 2,12-dimethyltridecan-4-one (19), 2-methyltridec-2-en-4-one (23), and a series of phenyl ketones, among them 1-phenyldecan-1-one (14) and 9-methyl-1-phenyldecan-1-one (16), whereas strain DW4/3-1 emitted traces of 10-methylundecan-2-one (21). The biosynthesis of 14 and 16 was examined in feeding experiments with deuterated precursors carried out on agar plate cultures. The leucine-derived starter unit isovalerate was shown to be incorporated into 16, as was phenylalanine-derived benzoic acid into both 14 and 16. The results point to formation both of the phenyl ketones and of the structurally related aliphatic ketones through an unusual head-to-head coupling between a starter unit such as benzoyl-CoA and a fatty acyl-CoA, followed by decarboxylation.     

甲醛法测定铵盐含氮量

对甲醛法测定铵盐含氮量进行了研究，提出采用百里酚酞和酚酞混和指示剂进行测定。该法简单、快速、准确，能满足生产实际和样品检验需要。     

Fabrication of TiO2 composite materials for air purification by magnetic field effect and electrocodeposition

Novel air purification materials were fabricated by the application of a magnetic field. In a magnetic field perpendicular to a copper plate, nickel particles with a diameter of 10 m were arranged to form numerous pillar-like structures on the matrix surface, and copper as a binder was deposited onto the three-dimensional surface. The total surface area of the pillars and the matrix increased with the magnetic flux density, up to about 800 cm² per cm² of the original matrix surface at 6.2 T. After successful codeposition of TiO₂ particles on the fabricated materials by electroplating, their photocatalytic activities were evaluated on the basis of the removal efficiency of nitrogen oxides (NO _x ), which are some of the most hazardous air pollutants. It was concluded that the samples with the pillar-like structures had two opposite characteristics: large surface area as a positive effect and shadowing against ultraviolet (UV) irradiation as a negative effect. However, total photocatalytic activity increased to twice as much as that of the flat sample by improving the UV irradiation method and the preparation condition of the materials     

Influence of volatile matter and deposited carbon on coke yield from coals

The relations between coke yields and the volatile matter content of 30 individual and 30 blended coals were investigated. Coke yields and deposited carbon related to volatile matter content can be expressed in the following equations: CY (%) = 97.89?0.86 VMch+VMc; and DC (%)= ?2.24+0.16 VMch; where: CY=real coke yield; VMch = volatile matter content of charging coal; VMc=volatile matter content of coke, and in the case of <2%; DC = deposited carbon. The test results show excellent correlation with practice.     

改性丙-叔共聚乳液在天然石漆生产中的应用

以丙烯酸酯-叔碳酸乙烯酯共聚乳液为基料生产的天然石漆，具有形象逼真、不褪色、耐水耐碱性好、抗紫外线辐射性强等特点。