VARIATION FEATURES OF PRECIPITATION IN GUANGXI

VariationfeaturesofprecipitationinGuangxiUnevendistributionofprecipitationinareas　ByreasonofcomplexlandforminGuangxi,theprecipitationvariesindifferentregionsandisgenerallyabundantinthesouthandthenorth,littleinthemiddleregion;abundantintheeastandlittleinthewest;abundantinhillyareasandlittleintherivervalleysandbasins;abundantinwindwardslopesandlittleinleewardslopes;abundantincoastlandandlittleinis lands.Therearemainly 4 pluvialregionsand 2littlerainfallregions.The 4pluvialregionswithprecipitat…     

双室火灾烟气特性的实验研究

本文在１／２缩尺建筑模型中，取双室－走廊结构，以标准木垛为火源，对建筑火灾的初始阶段进行了实验模拟。着重研究了火灾初期的烟气特性及其变化，包括烟气温度及烟气中ＣＯ＿２气体和炭颗粒浓度。本文目的在于在探索和发展中等尺寸火灾实验模拟手段和方法的同时，定性地确定火源功率对烟气特性的影响，并积累一定的实验数据，为建筑火灾的分析和模化提供实验基础和依据。     

喷射溶气回流浮选工艺处理含油废水

采用喷射溶气回流浮选工艺处理含油废水，替代原来的全加压溶气浮选工艺，提高了浮选过程的处理效果，增强了系统的抗负荷冲击能力，浮选出水油含量由原来的〈４０ｍｇ／Ｌ降至〈２０ｍｇ／Ｌ，ＣＯＤ由原来的〈１５０ｍｇ／Ｌ降至〈１１０ｍｇ／Ｌ。     

Modelling nitrogen fluxes at the landscape scale

The distribution and impacts of different nitrogen pollutants are inextricably linked. To understand the problem fully, the interactions between the different pollutants need to be taken into account. This is particularly important when it comes to abatement techniques, since measures to reduce emissions of one nitrogen pollutant can often lead to an increase in another. This project represents a step towards greater understanding of these issues by linking together new and existing nitrogen flux models into a larger framework. The modelling framework has been constructed and some of the nitrogen flows between fields, farms and the atmosphere have been modelled for a UK study area for typical farm management scenarios.     

Rapid amino acid cycling in arctic and antarctic soils

Amino acids constitute one of the largest inputs of organic nitrogen (N) to most polar soils and have been hypothesized to be important in regulating vegetational succession and productivity in Arctic ecosystems. Our understanding of amino acid cycling in these soils, however, is poor. The aim of this study was to investigate the size and rate of turnover of the amino acid pool in a range of Arctic and Antarctic soils. Our results indicate that in polar soils with either high or low ornithogenic inputs the amino acid pool is small in comparison to the inorganic N pool (NO^–₃ and NH⁺₄). The free amino acid pool constituted only a small proportion of the total dissolved organic nitrogen (DON) pool in these soils. Here we show that these low concentrations may be due to rapid use by the soil microbial community in both Arctic and Antarctic soils. The turnover of the amino acid pool in soil was extremely rapid, with a half-life ranging from 2 to 24 h, indicating that this N pool can be turned over many hundred times each summer when polar soils are frequently unfrozen. The implications of amino acids in N cycling and plant and microbial nutrition are discussed.     

Applying metabolic fingerprinting to ecology: The use of Fourier-transform infrared spectroscopy for the rapid screening of plant responses to N deposition

The potential for metabolic fingerprinting via Fourier-transform infrared (FT-IR) spectroscopy to provide a novel approach for the detection of plant biochemical responses to N deposition is examined. An example of spectral analysis using shoot samples taken from an open top chamber (OTC) experiment simulating wet ammonium deposition is given. Sample preparation involved oven drying and homogenisation via mill grinding. Slurries of a consistent dilution were then prepared prior to FT-IR analysis. Spectra from control, 8 and 16 kg N ha^–1 yr^–1 treatments were then subjected to cross-validated discriminant function analysis. Ordination diagrams showed clear separation between the three N treatments examined. The potential for using Calluna vulgaris (L.) Hull as a bioindicator of N deposition is further evident from these results. The results also clearly demonstrate the power of FT-IR in discriminating between subtle phenotypic alterations in overall plant biochemistry as affected by ammonium pollution.     

Mechanical and Barrier Properties of Biodegradable Films Made from Chitosan and Poly (Lactic Acid) Blends

Biodegradable film blends of chitosan with poly(lactic acid) (PLA) were prepared by solution mixing and film casting. The main goal of these blends is to improve the water vapor barrier of chitosan by blending it with a hydrophobic biodegradable polymer from renewable resources. Mechanical properties of obtained films were assessed by tensile test. Thermal properties, water barrier properties, and water sensitivity were studied by differential scanning calorimeter analysis, water vapor permeability measurements, and surface-angle contact tests, respectively. The incorporation of PLA to chitosan improved the water barrier properties and decreased the water sensitivity of chitosan film. However, the tensile strength and elastic modulus of chitosan decreased with the addition of PLA. Mechanical and thermal properties revealed that chitosan and PLA blends are incompatible, consistent with the results of Fourier transform infrared (FTIR) analysis that showed the absence of specific interaction between chitosan and PLA.