WIND TUNNEL SIMULATION OF WINDBLOWN SAND ALONG CHINA'S QINGHAI–TIBET RAILWAY

The Qinghai–Tibet Railway is frequently damaged by windblown sand, and this hinders railway operation. To better understand the characteristics of windblown sand near the railway, wind tunnel experiments were conducted for the Tuotuo River Section, a typical stretch suffering from windblown sand damage. According to climate data, the windy period combines with an arid seasonal climate to increase the risk of blowing sand in this area. Wind tunnel simulation results showed how the airflow interacted with the railway embankment to create sand deposition as well as aeolian erosion. Sand transport rates behind the railbed fitted a Gaussian function well. The results can be used to guide the design of sand‐control structures both in the study area and in other areas that experience threats from windblown sand. Copyright © 2012 John Wiley & Sons, Ltd.     

鲁北地区棉花与赤松茸大田轮作栽培技术

近年来,鲁北地区棉花生产呈现结构性萎缩态势。为充分利用棉花秸秆和冬闲棉田,提高植棉效益,初步探索了鲁北棉花与赤松茸大田轮作技术。从播种、田间管理、病虫害防治和采收等方面对其进行介绍,并分析了其发展前景,以期为该技术在鲁北地区的推广应用提供参考。     

醋酸改性电石渣催化酯交换特性研究

以醋酸为改性介质,从醇油摩尔比、催化剂质量分数、酯交换温度及时间等因素出发,并辅以热重分析仪、X射线衍射仪、N2吸附仪和哈米特指示剂等催化剂表征手段,通过酯交换实验系统研究改性电石渣催化酯交换的特性。酯交换原料油(花生油)脂肪酸中的碳原子长度主要为16~18碳;醋酸改性后,电石渣主要成分为(CH3COO)2Ca·0.5H2O,经800℃煅烧活化处理后转变为CaO,比表面积为19.07 m2/g、比孔容积为0.081 4 cm3/g,且能够表现出比未改性电石渣煅烧产物更强的催化酯交换性能。在醇油摩尔比15、催化剂质量分数4%、酯交换温度59℃、酯交换时间2 h的工况下,醋酸改性电石渣催化酯交换能取得甘油收率为96.79%,且重复使用5次时,甘油收率仍能达到92.90%。     

新形势下柑桔黄龙病防控工作思路和方法探析

近年来,柑桔黄龙病在多省份区域均有发生,甚至在部分柑桔生产区域造成了毁灭性的危害.新形势下,研究探讨适应地方工作实际情况的柑桔黄龙病防控工作思路和办法刻不容缓.本文以梧州市柑桔黄龙病防控工作为样本,坚持“以防为主,防治结合,群防群治”的原则,通过深入实践、调查了解,探讨总结了新形势下柑桔黄龙病防控综合治理的工作思路及方法,以期为当前柑桔产业的安全、健康和持续发展提供积极的参考和借鉴.     

油茶SRAP-PCR反应体系的建立和优化

为了建立油茶SRAP-PCR扩增体系,本研究使用单因素试验设计,对反应体系的Taq酶、Mg2＋、模板DNA、dNTP和引物浓度5个主要影响因子各设10个不同的水平梯度,筛选出适宜的因子范围;在此基础上,进一步采用L16（45）正交设计,对影响油茶SRAP-PCR反应体系的5个因素在4水平上进行优化,建立了油茶SRAP-PCR最佳反应体系,即25μL体积中包含模板DNA30ng,Mg2＋2.8mmol/L,引物0.44μmol/L,dNTP0.2mmol/L和Taq酶1.0U。该SRAP-PCR体系的建立为油茶种质资源遗传多样性分析、品种鉴定及指纹图谱构建等研究提供了一个标准化的程序。     

Concentration Distribution and Bioaccessibility of Trace Elements in Nano and Fine Urban Airborne Particulate Matter: Influence of Particle Size

Trace elements, especially those associated with fine particles in airborne particulate matter (PM), may play an important role in PM adverse health effect. The aim of this paper is to characterize elements in a wide particle size range from nano (57–100 nm) to fine (100–1,000 nm) and to coarse (1,000–10,000 nm) fractions of two urban PM samples collected in Ottawa. Size-selective particle sampling was performed using a micro-orifice uniform deposit impactor, and element concentrations were determined in each different size fraction by inductively coupled plasma-mass spectroscopy. A general trend of increasing element concentration with decreasing aerodynamic diameter was observed for elements V, Mn, Ni, Cu, Zn, Se, and Cd, indicating they were predominately concentrated in the nanoparticle size range. Other elements including Fe, Sr, Mo, Sn, Sb, Ba, and Pb were predominately concentrated in the fine-size range. Increased concentration of elements in the nano and fine particle size range is significant due to their ability to penetrate into the deepest alveolar area of the lungs. This was confirmed by the calculation of median concentration diameters, which were less than 800 nm for most of the investigated elements. Particle size distribution and element correlation analysis suggest that the elements concentrated in the nano- and fine-size fractions originated mainly from vehicular combustion and emission. Long-range airborne transport and soil or road dust resuspension may also contribute. Particle size had an important effect on element bioaccessibility for the studied urban PM samples showing a general trend of increasing element bioaccessibility with decreasing particle size. These results emphasize the importance of acquiring information on nano and/or fine PM-bound elements and their bioaccessibilities for accurate element and PM exposure assessment.     

Effects of Enhanced UV-B Radiation on N2O Emission in a Soil-Winter Wheat System

An outdoor pot experiments was conducted to investigate the effects of enhanced ultraviolet-B (UV-B) radiation on nitrous oxide (N₂O) emissions from soil-winter wheat systems. The enhanced UV-B radiation treatments were simulated by 20% increase in its intensity. N₂O fluxes were measured with a static opaque chamber-gas chromatograph method. The results showed that enhanced UV-B radiation did not change the seasonal patterns of N₂O emissions. Compared to the controls, the enhanced UV-B radiation reduced N₂O fluxes by 16.4% (p?=?0.015) during the elongation-booting stage, while it had no significant effects on N₂O fluxes in the turning-green and heading-maturity phases. During the turning green-overall heading span, the accumulative N₂O was largely decreased by the enhanced UV-B radiation (p?<?0.05). From the overall heading to maturity, however, the effects of enhanced UV-B on N₂O emissions were not pronounced (p?>?0.10). At the elongation-booting stage, enhanced UV-B increased soluble proteins content in leaves, NO ₃ ^- -N and NO ₄ ⁺ -N content in rhizosphere soil, and soil microbial biomass C (C _mic) and N (N _mic; p?<?0.05), as well as microbial biomass C:N ratio changing from 5.0 to 6.8. Our findings suggest that the effects of enhanced UV-B radiation on N₂O emissions differed with winter wheat developmental stages. To assess the overall effects of enhanced UV-B radiation on N₂O emissions from agroecosystems, nevertheless, more field measurements deserve to be carried out in various cropping systems.     

基于电子鼻的鱼粉中挥发性盐基氮检测模型比较

挥发性盐基氮（TVB-N）是表征鱼粉新鲜度的主要指标之一,为了探讨基于电子鼻系统检测鱼粉新鲜度的可行性,研制了检测鱼粉中TVB-N质量分数的电子鼻测量系统。该系统主要由氧化锡气敏传感器阵列、便携式数据采集设备和基于LabVIEW的采集程序组成。利用该系统对不同TVB-N质量分数的鱼粉样本进行气味信号采集,同时对鱼粉样本中的TVB-N的质量分数采用半微量凯式定氮法进行检测,利用2σ准则对传感器响应值进行数据剔除处理,建立了鱼粉中TVB-N质量分数的主成分分析（PCA）、多元线性回归（MLR）、BP神经网络模型,并用预测样本对模型进行验证。试验结果为：3种模型TVB-N质量分数预测值与实测值之间的决定系数R2、预测标准误差SEP、最大相对误差RE-max及平均相对误差RE-mean分别为0.48、10.25、13.62%、6.06%;0.59、9.14、13.91%、5.57%;0.94、3.64、6.30%、1.88%。BP神经网络效果最好,多元线性回归次之,主成分分析最差。研究结果表明,利用电子鼻技术可以有效对鱼粉中TVB-N质量分数进行检测。     

耕地利用生态社会效益测算方法及其应用

耕地利用生态社会效益测算是耕地保护经济补偿标准确定的依据。该文首先基于耕地利用过程中的生态系统服务功能重构了耕地利用效益体系,并对其内涵进行了界定和分析。然后以河南省焦作市为研究区域,选取2000、2002、2004和2006年4期数据,运用当量因子法和替代成本法测算了各年耕地利用的生态社会效益理论值。在此基础上,引入社会发展阶段系数测度了不同质量级别单位面积耕地的生态社会效益现实值。研究结果表明：2000、2002、2004和2006年,焦作市耕地利用的生态社会效益理论值分别为10 699.3、10 830.9、14 186.2和15 542.3元/hm2,表明耕地利用的生态社会效益随社会经济发展水平提高和耕地资源的稀缺性增强而增加;耕地利用社会效益占生态社会效益比重从2000年的42.99%上升到2006年的48.41%,尤其是粮食安全效益比重上升更为明显,表明粮食安全效益和社会保障效益的重要性将日趋凸现,同时也表明以往忽视社会效益单纯的耕地生态效益补偿研究是片面的;基于耕地质量水平和社会发展水平的修正,焦作市2006年耕地生态社会效益的现实值从最低级别的4 653.2元/hm2上升到最高级别的9 333.6元/hm2,表明单位面积耕地生态社会效益现实值的高低与其质量高低和区域支付意愿大小密切相关。通过对焦作市耕地利用生态社会效益理论值与现实值的测算,为焦作市构建具有动态性和可调性的耕地保护经济补偿标准和补偿体系提供了理论 依据。     

水稻苗间除草装置工作机理分析

为了满足绿色环保大米生产需要,设计了一种水稻中耕苗间除草装置。对总体结构、关键部件的设计及工作原理进行了分析。选择秧苗插秧后第7 d进行除草试验,秧苗行距为30 cm,株距为14~16 cm。采用二次旋转正交试验方法,利用Design-Expert软件进行数据处理与分析,获得了弹齿式苗间除草盘转速、机器前进速度、除草深度之间交互作用对除草率及伤秧率的影响。得到影响除草作业质量的指标主次因素和各因素的显著性水平。根据田间试验结果,插秧7 d时除草装置的较优工作参数为：除草盘转速186 r/min,机器前进速度为0.47 m/s,除草深度为37 mm,此时伤秧率为3.9 %,除草率为75 %。研究结果为整机的设计提供了可靠依据。