黄土丘陵区典型植物种群下土壤大孔隙特征及其影响因素研究

采用亮蓝(Brilliant blue,FCF)野外染色示踪实验和图像分析技术,研究了陇中黄土高原安家坡流域典型植物种群下土壤大孔隙分布特征及其与植物种群和土壤物理性质的关系。结果表明:6种植物种群下土壤中的大孔隙流不同,大孔隙流使水分在土壤中的运移深度提高了2～3倍;随着土层深度的加深,6种植物种群下土壤的染色面积均呈减小趋势;6种植物种群下土壤中各级别大孔隙以2、3级大孔隙最多,平均占染色面积的29.3%和29.4%,其次是1级和4级大孔隙,分别占17%和19.8%,5级特大孔隙最低,占4.5%。大孔隙分布特征与土壤有机质含量和容重有关。     

魔幻与现实——评《大妈妈的葬礼》的反殖民主义和封建主义主题

本文以加西亚·马奎斯中篇小说《大妈妈的葬礼》为对象,分析作品中的反殖民主义和反封建主义思想。     

In vitro inhibition of ETEC K88 adhesion by pea hulls and of LT enterotoxin binding by faba bean hulls

Enterotoxigenic Escherichia coli (ETEC) expressing K88 (F4) adhesins are associated with post‐weaning diarrhoea in piglets. Different grain fractions from pea (Pisum sativum) and faba bean (Vicia faba) were tested in vitro for their capacity to counteract aetiological factors, which contribute to the development of diarrhoea. In detail, adhesion of E. coli O149:K91:K88ac (ETEC K88ac) to grain legume products, intended to impair the colonization of the host, was studied as well as interference with receptor binding of the pathogen’s heat‐labile enterotoxin LT, intended to reduce toxin‐inflicted gut cell damage. When comparing different pea and faba bean products tested for their binding capacity of ETEC K88ac, especially pea hulls, but also whole pea meal, starch‐enriched and protein‐enriched pea meal, and digestion‐resistant pea hull and meal fractions showed a higher binding of ETEC K88ac than faba bean products. In contrast to the ETEC K88ac adhesion results, bean hulls proved more effective than pea hulls in preventing GM1 receptor binding of LT. Previous small intestinal segment perfusion experiments we performed with ETEC K88ac‐challenged piglets indicated that both pea and bean hulls have the potential for successful application in diarrhoea prophylaxis and treatment, which is in agreement with and refined by our detection of their different modes of functioning.     

地肤子甲醇萃取物杀菌抑菌活性成分的初步研究

为探索藜科地肤属植物地肤种子的杀菌抑菌活性,本试验采用生物活性跟踪法对该植物的杀菌抑菌活性成分进行了初步的研究,并采用柱层析法对其成分进行分离。结果表明,甲醇萃取物的生物活性显著高于石油醚和氯仿萃取物(P<5%);分离的流分F13经活性测定后对桃褐腐病菌有较好的抑菌效果。     

An argument for reframing debates about corruption: Insights from Papua New Guinea

There have been few attempts to identify the way different perspectives of corruption are employed in Papua New Guinea (PNG). The paucity of such analysis makes it difficult to identify the way scholars and policy‐makers understand corruption in the country, in turn leading to potentially poor targeting of anti‐corruption programmes. This article categorises perspectives of corruption that are found in academic and policy accounts of PNG. It finds that this literature is marked by an over‐reliance on ‘mainstream’ Western interpretations of the definition, causes and solutions to corruption. In turn, it is argued that there is an important role that ‘critical’ and culturally aware academics can play in reframing debates about corruption in PNG and the Pacific.     

Anti sliding pile performance under acid stress coupling

Anti sliding piles are an important engineering structure used extensively in landslide prevention. Their durability influences their work lives. In a laboratory model experiment of a cantilevered anti sliding pile under acid stress coupling, the pile body displacement variation is monitored continuously, and both concrete strength and neutralization depth are tested. The results indicate that the concrete strength decreases gradually under acid stress coupling, while the displacement increases continuously. The neutralization depth of the concrete in the anti sliding pile is linear to the square of duration in acid stress coupling.     

Simulation of an adaptive anti slip regulation/hill start assist control system

Anti slip regulation (ASR) systems can maintain the slip rate within a certain range when a vehicle accelerates on low adhesive road surfaces and thus prevent the drive wheels from rotating uncontrollably. Hill start assist control (HAC) systems, the late     

Biochemistry of hexose and pentose transformations in soil analyzed by position-specific labeling and 13C-PLFA

Microbial transformations are key processes of soil organic matter (SOM) formation, stabilization and decomposition. Combination of position-specific ¹³C labeling with compound-specific ¹³C-PLFA analysis is a novel tool to trace metabolic pathways. This combination was used to analyze short-term transformations (3 and 10 days after tracer application) of two key monosaccharides: glucose and ribose in soil under field conditions. Transformations of sugars were quantified by the incorporation of ¹³C from individual molecule positions in bulk soil, microbial biomass (by CFE) and in cell membranes of microbial groups classified by ¹³C-PLFA.The ¹³C incorporation in the Gram negative bacteria was higher by one order of magnitude compared to all other microbial groups. All of the ¹³C recovered in soil on day 3 was allocated in microbial biomass. On day 10 however, a part of the ¹³C was recovered in non-extractable microbial cell components or microbial excretions. As sugars are not absorbed by mineral particles due to a lack of charged functional groups, their quick mineralization from soil solution is generally expected. However, microorganisms transformed sugars to metabolites with a slower turnover. The ¹³C incorporation from the individual glucose positions into soil and microbial biomass showed that the two main glucose utilizing pathways in organisms – glycolysis and the pentose phosphate pathway – exist in soils in parallel. However, the pattern of ¹³C incorporation from individual glucose positions into PLFAs showed intensive recycling of the added ¹³C via gluconeogenesis and a mixing of both glucose utilizing pathways. The pattern of position-specific incorporation of ribose C also shows initial utilization in the pentose phosphate pathway but is overprinted on day 10, again due to intensive recycling and mixing. This shows that glucose and ribose – as ubiquitous substrates – are used in various metabolic pathways and their C is intensively recycled in microbial biomass.Analyzing the fate of individual C atoms by position-specific labeling deeply improves our understanding of the pathways of microbial utilization of sugars (and other compounds) by microbial groups and so, of soil C fluxes.     

Fingerprinting sediment sources in a typical karst catchment of southwest China

Due to the complex hydrogeological conditions in karst regions, it is difficult to measure sediment source contributions at a catchment scale directly. The objective of this study was to quantify the relative contributions of sediment sources and their temporal variability in a karst catchment in southwest China. Karst depressions can trap eroded sediment similar to a dam or reservoir and, thus, are representative and typical test beds for identifying sediment sources in karst regions. Three sediment cores were taken from a karst depression, 58 soil samples from three potential sediment sources were collected, and 18 soil properties were analyzed. The relative contributions of cropland, forestland, and fissure or crack soils were calculated using a multivariate mixing model. The fingerprinting results demonstrated that the cropland was the main sediment source in karst catchment. Specifically, according to the mean sediment contributions of the three deposited sediment cores, the sediment contribution from cropland topsoil was 69.3%, varying from 46.9% to 92.3%, and forestland soil and crack soil accounted for 8.6% and 22.1% of the sediment yield, and varying from 2.8% to 16.5% and 4.8%–36.6%, respectively. This result indicated that great attention should be paid when using only a single core to quantify sediment provenance. Due to the deposited sediment was generally disturbed as cropland in the karst depression, the area that has not been disturbed in recent decades in depression was more appropriate to trace sediment sources in karst catchment. To the best of our knowledge, this study was the first to quantify the contributions of sediment sources in the karst catchment of southwest China. This study provides valuable information and a preliminary reference for applying a composite fingerprinting technique to quantify sediment sources in karst catchments.