Enzymatic treatment on cotton fibers: degradation kinetics of pectin and influence of shape change on adsorption

Alkaline pectinase was one of the most effective enzymes to treat cotton as alternative agent to replace the conventional alkaline method. Removal of pectin and cutin was considered the explanation for improvement of wettability as well as water adsorption on cotton fiber. However, degradation kinetics of pectin is unclear, and the influence of fiber shape on property changes after enzymatic treatment was ignored. The main objective of this work was to reveal interactions between pectinase and cotton fiber for mechanism study. A heterogeneous catalysis kinetic equation, which is associated with Langmuir adsorption model and enzyme deactivation, was used to describe the heterogeneous catalysis. The enzymatic process conditions were optimized. Raw cotton fibers, pectinase-treated and alkali-treated fibers were characterized by impurities content determination, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). Mechanism of water adsorption enhancement on treated fibers was discussed. In addition to elimination of the outer impurities, flat fibers with less twist and shape changes of lumen were also obtained to ensure better accessibility and water adsorption after enzymatic treatment.     

杭青梨澄清果汁加工中的护色条件和酶法液化技术

结果表明 :杭青梨果实经挑选、清洗、热烫、冷却后破碎 ,在破碎时用质量分数为 0 .4 g· kg-1的抗坏血酸处理 ,可防止果汁氧化褐变而保持淡黄色或黄白色 ;每公斤果浆加果胶酶量为 2 .5g,在 4 5℃下酶解 2 .5h,出汁率可提高 12 .1% .果胶酶用量是影响梨果出汁率的主要因素     

果园环境参数远程检测WSN网关节点设计

为解决果园环境参数远程检测中网关节点因电磁干扰造成ZigBee模块传输距离过短,不能满足动态配置ZigBee网络的不足,采用核心板加底板及模块化接口的硬件设计思路,提高系统的抗电磁干扰能力;采用串口编程及单线程通信策略实现ZigBee网络动态配置,用判断2次接收数据差值及变化趋势决定是否传输数据以减小功耗.测试表明,网关节点可稳定采集数据并远程传输,提高了抗电磁干扰能力,与电路板集成设计相比通信距离增加了1倍,并可灵活地动态配置ZigBee网络.     

种植水稻和长期施用无机肥对红壤氨氧化细菌多样性和硝化作用的影响

以中国科学院红壤生态试验站发育于第四纪红黏土的植稻红壤为研究对象,研究了长期种植水稻和施用无机肥对土壤β-变形杆菌纲中氨氧化细菌多样性和硝化作用的影响。原始红壤改种水稻13年后,氨氧化细菌16SrDNA的DGGE条带数量增加,条带谱与原始红壤的差异较大,相似性为61%,说明种植水稻后土壤氨氧化细菌群落结构发生了变化。PCR-DGGE方法研究结果也显示,长期施用无机氮肥的处理(NP、NPK和NK),DGGE带谱相似性较高,达到73%,硝化率和硝化势均高于未施用氮肥的处理。逐步回归分析显示硝化率和硝化势均随着土壤脲酶活性的提高而显著增加。推测尿素可提高土壤水解氮含量,使土壤脲酶活性提高,促进硝化细菌的生长,进而提高硝化率和硝化势。     

Survival and serum biochemical responses of spotted sea bass Lateolabrax maculatus during simulated waterless live transportation

Waterless live fish transportation is an alternative and promising transport strategy, which may reduce shipping costs, increase stocking density and improve survival of some species. Spotted sea bass is one of the most economically important marine fish in China. However, waterless transportation has not yet been studied on spotted sea bass. To explore the possibility of waterless transportation of spotted sea bass and its sublethal stress responses, the survival rate and dynamics of blood biochemical parameters were evaluated in the present study by preserving it under no water, less water and water (control) conditions for 9 hr. The serum biochemical parameters including total protein, cortisol, glucose, lactate, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total carbon dioxide (TCO₂), creatinine, blood urea nitrogen (BUN), ammonia, superoxide dismutase (SOD) activity and malonaldehyde (MDA) were investigated. Results showed that the survival rates of fish in all groups gradually declined with time increasing. At the end of transportation, the survival rates in the control group, less‐water group and no‐water group decreased to 49.11%, 15.60% and 23.96% respectively. Significant changes were observed in several selected serum biochemical parameters, including glucose, lactate, ALT, TCO₂, BUN and ammonia during simulated waterless transportation, which might negatively affect the physiological homeostasis of fish, leading to the high mortality in present study. In general, waterless transportation of spotted sea bass was possible, but it might be rather suitable for short time than long time.     

植物乳杆菌对发酵奶油中胆固醇含量的影响

为了降低发酵奶油中胆固醇的含量,以植物乳杆菌为发酵菌种,通过正交实验研究了植物乳杆菌对发酵奶油中胆固醇含量的影响,并确定了植物乳杆菌参与下奶油的发酵工艺参数。结果表明,在发酵温度为41℃、发酵时间为6 h、接种量为9%,菌种(嗜热链球菌∶保加利亚乳杆菌∶植物乳杆菌)比例为1∶1∶1时,植物乳杆菌参与下的发酵工艺可使奶油中胆固醇含量由0.531 mg·g-1降至0.384 mg·g-1,胆固醇降解率为31%。     

Determining the bioavailability of contaminants and assessing the quality of sediments

Background, Aims and Scope  

Our study determined if and when an avoidance or attraction behavioural response would be displayed by Ilyanassa obsoleta when presented with a choice between harbour and reference sediments. Our goal was to develop a non-lethal approach that could be used in future assessments of the environmental quality of field sediments.     

黄河三角洲退化湿地土壤养分、微生物与土壤酶特性及其关系分析

为了揭示黄河三角洲湿地退化与土壤的关系,为湿地生态修复和有效利用湿地资源提供理论依据,对黄河三角洲退化湿地不同演替阶段的土壤酶活性、土壤养分和土壤微生物特性及土壤酶与养分和微生物的关系进行分析。结果表明:随着湿地由白茅群落到光板地的逆向演替,土壤脲酶、蛋白酶活性呈逐渐下降趋势,碱性磷酸酶和过氧化氢酶活性变化规律与其相似;不同演替阶段土壤酶活性表现出差异性,各种酶之间蛋白酶活性最高;土壤养分质量含量基本都随着湿地逆向演替的进行而递减,不同演替阶段土壤养分质量分数差异显著;退化湿地土壤中各种微生物数量存在明显差异性,在土壤微生物群落中,细菌数量所占比例最大,在各类微生物中占绝对优势,其次为放线菌,真菌数量最少;白茅群落阶段细菌和真菌数量最多,柽柳群落阶段放线菌数量最多;土壤酶与土壤养分、土壤微生物存在密切正相关关系;细菌与脲酶和过氧化氢酶有密切关系,真菌与脲酶、过氧化氢酶和碱性磷酸酶都具有显著的相关性。     

Integrated disease management of ascochyta blight in pulse crops

Ascochyta blight causes significant yield loss in pulse crops worldwide. Integrated disease management is essential to take advantage of cultivars with partial resistance to this disease. The most effective practices, established by decades of research, use a combination of disease-free seed, destruction or avoidance of inoculum sources, manipulation of sowing dates, seed and foliar fungicides, and cultivars with improved resistance. An understanding of the pathosystems and the inter-relationship between host, pathogen and the environment is essential to be able to make correct decisions for disease control without compromising the agronomic or economic ideal. For individual pathosystems, some components of the integrated management principles may need to be given greater consideration than others. For instance, destruction of infested residue may be incompatible with no or minimum tillage practices, or rotation intervals may need to be extended in environments that slow the speed of residue decomposition. For ascochyta-susceptible chickpeas the use of disease-free seed, or seed treatments, is crucial as seed-borne infection is highly effective as primary inoculum and epidemics develop rapidly from foci in favourable conditions. Implemented fungicide strategies differ according to cultivar resistance and the control efficacy of fungicides, and the effectiveness of genetic resistance varies according to seasonal conditions. Studies are being undertaken to develop advanced decision support tools to assist growers in making more informed decisions regarding fungicide and agronomic practices for disease control.     

热带次生林经营引入物种选择

在国际热带木材组织（ITTO）的资助下,广东省林业科学研究院在广东新会和海南通什开展了“旨在提高生态和经济效益的热带地区次生林经营研究与示范”活动。其目的是通过在干扰破坏较严重的次生林中引入具有较好生态和经济效益的优良物种,使林分物种增加,林区居民能从经营中取得非木质产品的经济收益,达到保护和促进次生林的生长发育的目的,实现森林可持续经营的目标。在广东新会热带次生林经营研究与示范区活动中,选择101个引入物种进行试验研究,其中区域缺失和退化的乡土树种68种,占67．3％;外来树种13种,占12．9％;非木质产品物种20种,占19．8％。总结了低质低效次生林经营中物种选择的原则、方法和经营效果。