Integration of polymer elements at the end of optical fibers by free-radical photopolymerization

In this article, we report a method of free-radical photopolymerization on the top end of a single-mode optical fiber. The process is very simple to carry out and uses the visible light guided in the fiber. It permits one to produce, on the fiber end, a micronic polymer tip which may be viewed as an extension of the fiber core and whose optical properties improve the intrinsic capability of the fiber, particularly in terms of efficiency of coupling with a laser source. Formation of the tip is explained by self-guiding of the light within the material and photophysical response of the material.     

Effect of concentration,pH and ionic strength on the kinetic self-assembly of acid-soluble collagen from walleye pollock (Theragra chalcogramma) skin

The effects of concentration, pH value and ionic strength on the kinetic self-assembly of acid-soluble collagen from walleye pollock (Theragra chalcogramma) skin were investigated. A two-phase kinetic process was provided which included the formation of nucleus center and nucleus growth, the first phase being the controlled step for collagen self-assembly. Collagen showed marked assembly behavior when concentration reaching and above 0.6 mg/mL, and higher concentration could accelerate collagen self-assembly. Rate constants of the first and second assembly phase both increased with pH to a maximum around pH 7.2 and then decreased, indicating that pH 7.2 was the optimum pH value for collagen self-assembly. The kinetics of collagen self-assembly could be modulated by NaCl concentration. The concentration of NaCl from 30 to 60 mM was more suitable to self-assemble for pollock skin collagen.     

Computational analysis methods to quantify a.c. impedance data

For the interpretation of a.c. impedance data, two data analysis techniques are described and evaluated. The first method is a least squares analysis of a nonlinear model. Modifications to a previously published algorithm, CIRFIT, include a least squares estimate of the double layer capacitance. Also, two convergence techniques for CIRFIT were explored and evaluated. The second method is a nonlinear least squares analysis of an equivalent circuit consisting of three RC parallel combinations, the final circuit containing a diffusion limiting impedance. The method satisfactorily estimated the component values of the proposed equivalent circuit, even when two time constants were closely spaced. Both methods could be valuable in analyzing, modeling, and interpreting experimental a.c. impedance data.     

Modelling net primary productivity of terrestrial ecosystems in East Asia based on an improved CASA ecosystem model

By using a land cover map, normalized difference vegetation index (NDVI) data sets, monthly meteorological data and observed net primary productivity (NPP) data, we have improved the method of estimating light use efficiency (LUE) for different biomes and soil moisture coefficients in the Carnegie–Ames–Stanford Approach (CASA) ecosystem model. Based on this improved model we produced an annual NPP map (in 1999) for the East Asia region located at 10–70° N, 70–170° E (about 19.66% of the terrestrial surface of the Earth). The results show that the mean NPP for the study area in 1999 was 374.12 g carbon (C) m^?2 year^?1 and the total NPP was 1.096 × 10¹⁴ kg C year^?1, making up 17.51–18.39% of the global NPP. Comparison between the estimated NPP obtained from this improved CASA ecosystem model and the observed NPP obtained from two NPP databases indicates that the estimated NPP is close to the observed NPP, with an average error of 5.15% for the study region. We used two different land cover maps of China to drive the improved CASA model by keeping other inputs unchanged to determine how the classification accuracy of the land cover map affects the estimated NPP, and the results indicate that an accurate land cover map is important for obtaining an accurate and reliable estimate of NPP for some regions, especially for a particular biome.     

利用TG-FTIR研究造纸黑液碱木质素的热解机理

采用热重-傅里叶红外光谱（TG-FTIR）联用的分析方法对造纸黑液碱木质素的热解失重特性和产物生成特性进行了研究。结果表明：碱木质素热解失重过程可分为3个阶段,其中200~500℃是碱木质素主要的热解挥发阶段,反应符合一级反应动力学模型,利用Coats-Redfern动力学模型计算得出不同升温速率下热解主反应的表观活化能为39.3~43.1 kJ/mol。FTIR的实时分析结果表明：碱木质素热解的气态产物主要有H₂O、CO₂、CO、CH₄、甲醇、酚类和N₂O;产物中的CH₄、甲醇、酚类和N₂O主要在300~500℃区间内释放,随着热解温度的升高,这些气态产物在420℃附近集中释放,且产量达到最大。     

基于紫外吸收光谱法的水中氨氮浓度测量方法研究

氨氮是水中常见的污染物,是各类水质检测重要 的指标。水中氨氮含量超标会影 响水生植物、动物的生长,导致水体环境恶化,水环境受到污染。因此,加强水中氨氮 的监测尤为重要。本文基于紫外光谱检测技术,搭建了水中氨氮浓度紫外光谱检测系统。 通过检测系统将液相氨氮转换为气相氨气,获得氨气在 190-235nm波长间的紫外吸 光度,并分别采用傅里叶滤波和傅里叶变换两种数据处理方式对吸光度信号进行分析。 结果表明,经傅里叶滤波后氨气的吸光度在190-235nm波长间存在明显的周期性的峰 值,周期约为4nm,随着氨气浓度的增加其吸光度峰值也增大。通过最小二乘法拟合 发现,氨气的吸光度和浓度之间存在着良好的线性关系,相关系数为0.99814。经傅里 叶变换后的吸光度信号在频域中存在特征频率,通过拟合发现,振幅强度与氨氮浓度之 间同样存在线性关系,相关系数为0.98686。实验证明可以根据氨气吸 光度获得氨氮的 浓度,为水中氨氮浓度的检测提供了新的检测手段。     

基于SAILH模型的植被冠层NDVI二向性分析

NDVI是植被遥感中最为常用的一种植被指数,建立NDVI与其他冠层参数模型必须考虑其方向性问题.本文基于SAILH模型讨论了连续植被冠层NDVI的二向性特征,并分析了叶面积指数、叶倾角分布、热点参数以及太阳天顶角和相对方位角对NDVI的影响.研究表明冠层NDVI在主平面观测方向存在一个明显的负热点,前向散射方向的NDV...     

Economic evaluation of common reed potential for energy production: A case study in Wuliangsuhai Lake (Inner Mongolia,China)

Wuliangsuhai Lake is one of the largest wetlands in Inner Mongolia, China, half covered by large and highly productive Common Reed (Phragmites australis) stands. However, benefits from current utilization practices do not cover the costs of harvesting. Against this background, Wuliangsuhai Lake is taken as a case study for the assessment of the potential use of reed biomass for energy production. Taking into account, both the present and the potential reed availability, four scenarios are considered, i.e. (1) a decentralized application in household stoves, (2) a centralized reed supplied combined heat and power gasification, (3) a direct combustion plant and (4) a co-firing in existing coal plants. Two field campaigns have been conducted firstly collect information about the current situation of the reed and coal market and secondly to measure reed above-ground biomass. The suitability of reed for thermochemical conversion processes has been evaluated by means of chemical-physical, calorimetric, and thermal analyses of the samples. The potential energy production is valued regarding the profitability on the current Chinese energy market. Possible subsidies for reed as a renewable resource are taken into account. The evaluation has shown that reed has the potential to act as an energy feedstock. In relation to the considered study site, reed energy use can be profitable on the household level, in CHP combustion plants and in co-combustion. Gasification CHP plants are not economic feasible under current conditions. The results show that reed can be a sustainable alternative to highly health and environment damaging coal.     

水质在线安全生物预警系统模拟预警及应用

水质安全在线生物预警系统可以实现水体突发性污染事故安全预警,根据受试生物生物学指标变化对水体内多种污染物的综合毒性进行监测。模拟预警结果表明,水质安全在线生物预警技术通过低压电信号采集日本青鳉的行为变化,并通过信号分析系统,结合行为变化阈值的设定,对水质状况进行综合分析,实现对污染水体的水质变化报警。     

Antibiotic and antifouling compound production by the marine-derived fungus Cladosporium sp. F14

A marine-derived fungus, Cladosporium sp. F14, was studied for its ability to produce antibiotic and antifouling compounds on different cultivation media. The fungus grew well on tryptone or yeast extract media, slowly on ammonium or nitrate media, and not at all on urea media. In nutrient-enriched cultivation media, this strain produced antibiotic and antifouling compounds in the presence of glucose or xylose. These bioactive compounds were rarely produced in the absence of the sugars, even though the fungal cells grew well under these conditions. Fungal extracts decreased the attachment of bryozoan larvae (Bugula neritina) and showed antibiotic activity towards 6 tested bacterial species. Metabolite profiles of the fungus revealed by gas chromatography – mass spectrometry (GC–MS) showed clear differences when glucose was present in or absent from the culture medium. This study provides another evidence that marine fungus has the ability to produce antibiotic and antifouling compounds.