Microbial respiration activities related to sequentially separated, particulate and water-soluble organic matter fractions from arable and forest topsoils

This study aimed to reveal differences in the relevance of particulate as well as water-soluble organic matter (OM) fractions from topsoils to the easily biodegradable soil organic matter (SOM). We selected eight paired sites with quite different soil types and soil properties. For each of these sites, we took samples from adjacent arable and forest topsoils. Physically uncomplexed, macro-, and micro-aggregate-occluded organic particle, as well as water-soluble OM fractions were sequentially separated by a combination of electrostatic attraction, ultrasonic treatment, density separation, sieving, and water extraction. The easily biodegradable SOM of the topsoil samples was determined by measuring microbial respiration during a short-term incubation experiment (OC_R). The organic carbon (OC) contents separated by i) the physically uncomplexed water-soluble OM, ii) the macro-, and iii) the micro-aggregate-occluded organic particle as well as water-soluble OM fractions were significantly correlated with OC_R. The correlation coefficients vary between 0.54 and 0.65 suggesting differences in the relevance of these OM fractions to the easily biodegradable SOM. The strongest correlation to OC_R was detected for the OC content separated by the physically uncomplexed water-soluble OM indicating the most distinct relation to the easily biodegradable SOM. This was found to be independent from land use or soil properties.     

Influence of tree crown characteristics on the local PM10 distribution inside an urban street canyon in Antwerp (Belgium): A model and experimental approach

Apart from influencing the amount of leaf-deposited particles, tree crown morphology will influence the local distribution of atmospheric particles. Nevertheless, tree crowns are often represented very rudimentary in three-dimensional air quality models. Therefore, the influence of tree crown representation on the local ambient PM₁₀ concentration and resulting leaf-deposited PM₁₀ mass was evaluated, using the three-dimensional computational fluid dynamics (CFD) model ENVI-met^® and ground-based LiDAR imaging. The modelled leaf-deposited PM₁₀ mass was compared to gravimetric results within three different particle size fractions (0.2–3, 3–10 and >10 μm), obtained at 20 locations within the tree crown. Modelling of the LiDAR-derived tree crown resulted in altered atmospheric PM₁₀ concentrations in the vicinity of the tree crown. Although this model study was limited to a single tree and model configuration, our results demonstrate that improving tree crown characteristics (shape, dimensions and LAD) affects the resulting local PM₁₀ distribution in ENVI-met. An accurate tree crown representation seems, therefore, of great importance when aiming at modelling the local PM distribution.     

Hyper-spectral estimation of wheat biomass after alleviating of soil effects on spectra by non-negative matrix factorization

Hyper-spectral technology has been proven to be an effective method for the fast and non-destructive monitoring of crop biomass. However, the biomass estimation accuracy of this method is limited due to the effects of background factors, such as soils and water. In this study, a spectral separation method, non-negative matrix factorization (NMF), was proposed to alleviate the effects of soil on spectra. With the application of the NMF method, pure vegetation spectra were extracted from the field-observed spectra of wheat canopy, which were collected in four growing seasons from the tillering to the booting stages of wheat. Then, prediction models of wheat biomass (WB) were established and validated using the extracted spectra with the partial least squares regression (PLSR) method. The results showed that the NMF method could effectively separate the vegetation spectra from the mixed canopy spectra. Based on the extracted vegetation spectra, the WB prediction accuracy could be greatly improved with an increase of 31.7% for the R²_p and an increase of 46.6% for the ratio of performance to deviation (RPD) as compared to the original spectra, indicating that the NMF method could significantly improve the performance of the WB prediction model. This method has potential application in the estimation of biomass using remote sensing technology.     

灌木围障预防兔害对油松高影响研究

产生兔害的根本原因是竞争有限的空间和食物资源,灌木围障将野兔与林木隔离,不限制其在林内的活动,是一种环境友好型的林木兔害预防方法.为了掌握灌木围障对林木高的影响,研究了用沙棘、黄刺玫和其他灌木枝条围罩处理对油松高的作用.试验在当年油松定植时布设,设罩盖与不罩盖处理,5次重复,苗龄3 a,各处理300株.2006年5月定植时对处理区的油松进行测量、标记.处理后2007-2011年5月各调查1次油松高生长量.结果表明:灌木围障隔离对油松高有促长作用,且灌木篱笆促长作用优于灌木围墙.桥北灌木篱笆区定植5 a的油松综合增益指数为20.6％±1.35％,比灌木围墙处理提高了9.3％±1.90％,差异极显著(F=23.299,p=0.000).而旬邑林区两种处理间油松净高增益指数差异不显著(F=2.429,p=0.126),综合增益指数相差2.7％±1.03％.两地各处理油松净高增益大小依次为桥北篱笆＞桥北围墙＞旬邑篱笆＞旬邑围墙.随着定植年限的延长,两地油松净高增益指数有进一步扩大的趋势,油松高生长差距逐渐扩大.     

砂土抗剪强度数值模拟的关键技术研究

利用二维颗粒流软件PFC 2D对砂土的抗剪强度进行研究。通过建立数值试样模型、设立相对合理参数、引用＂橡皮膜＂程序等方法对砂土的三轴剪切试验进行数值模拟,模拟的结果较好地反映了砂土的力学性质。     

汉语自动分词中的神经网络技术研究

本文讨论了人工神经网络技术应用于汉语自动分词的映射模型和性能，着重分析网络结构和学习算法对歧义词切分的影响，在大量仿真实验的基础上，对其性能进行评价。     

乳状液膜在金属离子测定中的分离富集作用

简要介绍乳状液膜技术在金属离子分析测定中的分离富集作用以及新的研究和应用进展状况。     

电选法回收废印刷线路板中金属Cu的研究

采用破碎机和高压电选机对废印刷线路板中金属Cu进行回收.结果表明,破碎产物粒度<0.9mm时金属的单体解离度较高,可以作为分选的原料.物料在电选过程中的动力学分析表明,影响电选效果的主要因素为电极电压、滚筒转速、电晕电极距及物料粒度.经正交实验优化影响参数后,-0.9+0.074mm粒级的破碎产物一次电选所得精料中Cu的富集情况较好,Cu品位由32.0%富集到63.6%,回收率为78.7%.     

48小时母仔分离对自由哺育或控制哺育母兔性能的影响

本试验估测了48小时母仔分离（Doe-Litter Separation,DLS)对不同哺育方式（自由或控制）的母兔进行周期发情的效果。结果表明：控制哺育相对于自由哺育来说，可提高哺育母兔繁殖率（68．62％和46．00％，P＜0．01），降低1－9日龄期间仔兔死亡率（8．00％和10．74％，P＜0．05），同时也提高了母兔淘汰率（67．92％和56．41％，P＜0．05）和乳房炎的发病率（15．09％和11．11％，P＜0．05）。当母仔分离的方法使用在自由哺育方式中时，母兔的发病率和繁殖率均能得到极显著的改善（74．18％和53．72％，P＜0．01；69．23％和46．00％，P＜0．01）。然而，当母仔分离的方法使用在控制哺育方式中时，母兔的发情率和繁殖率的改善不及自由哺育中的应用效果（73．35％和58．47％，P＜0．05；77．77％和69．62％，P＞0．05）。48小时母仔分离时自由或控制两种哺育方式来说，均能显著降低哺乳期间仔兔的死亡率（18．69％和22．35％，P＜0．05；15．47％和19．52％，P＜0．05），尤其是9－42日龄期间仔兔的死亡率（8．15％和14．29％，P＜0．01；8．57％和11．98％，P＜0．01）。哺育方式和母仔分离对哺乳母兔窝产仔数、窝产活仔数、断奶个体重和断奶前日增重均无明显影响。     

马铃薯损伤诱导型启动子Wun1基因的克隆及其GFP表达活性

通过聚合酶链式反应(PCR),以马铃薯基因组DNA为模板,根据已报道Wun1序列设计了一对特异引物,在优化的PCR反应条件下扩增出了Wun1基因片段,通过序列分析与文献报道的碱基序列有96.86%的同源性,该基因已登录到GenBank(No.AY803296)。以pBIPG(携带GFP基因)的质粒DNA为模板,通过PCR技术亚克隆到了源自水母(Aequorea)大小为756bp的绿色荧光蛋白(GFP)基因,与已知序列同源率为100%。利用GFP基因作为报告基因,构建了用于比较鉴定所克隆启动子活性的pBIG(35S-GFP)和pBIWG(Wun1-GFP)两个植物表达载体,采用基因枪法进行对洋葱表皮细胞的遗传转化,检测Wun1启动子在受体细胞中调控基因表达的活性,结果表明克隆到的Wun1启动子活性强于组成型表达的35S启动子,GFP瞬时表达的分析方法也让我们有效的筛选到用于进行马铃薯抗病育种的调控元件。