基于光能利用率模型估算大兴安岭北部火烧迹地生产力

以大兴安岭火后不同强度(轻度、中度、重度)及未火烧区森林为研究对象,利用光能利用率模型和ETM+影像,结合植被资料,估算了火烧结束12 a后(1999年8月)过火区的针叶林、阔叶林、针阔混交林的净初级生产力(Net primary productivity,NP,P),分析了1987年"5.6"大火不同强度火烧对森林分布和生产力的影响。结果表明:轻度和中度过火区林地面积的比重与未过火区相近,且NP,P比未过火区高;重度过火区部分林地的比重降低,森林退化成非林地,但林地NP,P与未过火区相近。     

施肥对麻疯树幼树生长与叶片养分动态的影响

[目的]探讨麻疯树成熟叶片N、P2O5、K2O、Ca、Mg、Fe、Mn、Cu、Zn、B共10种营养元素含量的动态变化和相关性,为麻疯树科学施肥提供参考依据.[方法]选取长势一致的麻疯树进行每株0、0.2、0.4、0.6kg的复合肥施肥处理,在每月的中下旬取植株成熟叶片,测定其营养元素的动态变化特征,分析其相互关系.[结果]麻疯树叶片营养元素含量高低顺序为：K2O＞N＞Ca＞ Mg＞P2O5＞Mn＞Fe＞Zn＞B＞Cu.不同施肥处理对叶片营养元素含量有一定影响,其中N、K2O、Ca、Mn、Fe、Zn、B元素含量受施肥影响比较大,而P2O5、Mg、Cu受影响比较小.麻疯树的株高、总新梢生长量、地茎粗随着施肥量的增加而增加,果枝率随着施肥量的增加先增加后降低,果枝率最高的是施肥0.4 kg/株处理.[结论]施肥能促进麻疯树的生长,0.4 kg/株/年（15-15-15复合肥）时最利于麻疯树果枝的形成.麻疯树叶片的营养元素受施肥的影响,养分元素间有协同和拮抗作用,生产上要根据麻疯树的营养需求规律和需肥特性进行平衡施肥.     

拉美解决粮食问题的典范——以委内瑞拉粮食主权运动为考察对象

粮食主权作为一种宗旨,正成为发展中国家解决粮食问题的指导思想,委内瑞拉查维斯政府在土地改革基础上推行的粮食主权运动是最早实践粮食主权宗旨的国家之一。通过对委内瑞拉粮食主权运动推行的背景、过程、措施的分析阐述,认为拉美各国只要在政府层面制定一个清晰的规划和农业发展战略,能够适应粮食市场的发展规律,提高小农的生产力水平,同时能最大限度地减少发达国家廉价粮食的冲击就可以真正解决粮食匮乏所带来社会、经济等问题。     

厌氧发酵生物技术处理果蔬废弃物分析及展望——基于北京新发地农产品批发市场的调查

新发地作为北京市交易规模最大的农产品专业批发市场,其产生的垃圾（主要为果蔬垃圾）日益增加,已经严重影响附近居民的生活。通过对新发地市场实地调查,分析该地垃圾（主要为果蔬垃圾）的产生数量、成分和目前的处理方式,充分验证处理新发地垃圾的急迫性和重要性,以及厌氧发酵处理的可行性和优越性;此外,对新发地垃圾进行批式厌氧发酵产气试验,在添加底物为3gVS／L、污泥负荷（F／M）为0．5下,经过35d的发酵反应,累计产气量达701mL／gVs,挥发性固体去除率为80％,实验表明新发地垃圾产气潜力大,为实际解决新发地垃圾问题提供了理论保障．     

农户参与农地股份合作制意愿的影响因素研究——基于湖北省三汊镇的农户调查

农地股份合作制作为一种新的土地流转方式,在实践过程中极大地显示了其制度的优越性。通过对湖北省三汊镇农户的入户调查,采用Logistic模型,实证分析了影响农户土地入股意愿的内部因素,并加以规范分析找出了影响农户入股意愿的主要外部因素。研究结果表明,农户入股意愿主要受户主的职业、家庭主要收入来源和家庭人口数量等内部因素和劳保福利、完善的社保等外部因素的影响,并据此提出了相应的促进农地股份合作制的建议。最后,对其前景进行了展望。     

以“食品微生物学”为例探索基于工程认证的学生自主实践教学模式

针对"食品微生物学"实践教学,倡导以学生为中心、自主实践的教学理念,培养自主学习意识和科学素养,对实验课程的教学模式、考核评价等进行改革,优化考核评价体系,从而提高实验课堂效果,加强学生动手能力的培养。为解决复杂工程问题打下坚实的基础,有力支撑工程教育认证对课程教学指标点达成的要求。其他食品类基础实验也可借鉴"食品微生物学",不断完善食品科学与工程专业基础实验教学模式。     

Mercury distribution and speciation in floodplain soils and uptake into native earthworms (Diplocardia spp.)

Historically as part of its national security mission, the U.S. Department of Energy's Y-12 National Security Facility in Oak Ridge, TN acquired a significant fraction of the world's supply of elemental mercury. During the 1950s and 1960s, a large amount of elemental mercury escaped confinement and is still present in the watershed surrounding the Y-12 facility. Earthworms are key components in natural food chains, providing a food source for many small mammals and important food sources for small birds. The objectives of this study were to investigate the current status of mercury distribution and speciation and determination of mercury bioavailability to native earthworms in floodplain soils of East Fork Poplar Creek (EFPC) after decades of U.S. Department of Energy's remediation. The present study clearly shows that the total mercury in a tested floodplain field of EFPC was significantly below the US Department of Energy target 400 mg Hg/kg. The major mercury form in the current floodplain soils of EFPC is mainly the non-cinnabar mercury bound form in soil silicates (4 M HNO₃-extractable residual fraction). The results show strong linear relationships between mercury concentrations in native earthworms (both mature and immature groups) and the non-cinnabar mercury form. Native earthworms may be used as a potential mercury ecological bio-indicator (bio-marker) for demonstrating mercury bioavailability and ecotoxicity in the ecosystem.     

Purification, cloning, and immunological characterization of arginine kinase, a novel allergen of Octopus fangsiao

Arginine kinase (AK) is an important enzyme participating in energy metabolism in invertebrates, but, to date, there have been no reports that AK from octopus is an allergen. In this study, octopus AK was purified, and its molecular biological, immunological, and physicochemical characterizations were analyzed. The results showed that octopus AK was purified and confirmed by mass spectrometry for the first time, and its molecular mass was 38 kDa. The full-length gene sequence of octopus AK encompassed 1209 bp and was predicted to encode a protein with 348 amino acid residues. The homology of octopus AK and crustacean AK was about 54%, but the similarity between their three-dimensional structures was high. Octopus AK could react with mouse anti-shrimp AK and rabbit anti-crab AK polyclonal antibody singly. Octopus AK could also react with specific IgE of the sera from octopus-allergic patients effectively, whereas crab AK could inhibit the reaction between them. Finally, the IgE-binding activity of octopus AK could be reduced in the processes of thermal or acid-alkali treatment. In summary, AK was identified as a novel allergen in octopus, which had a sensitizing ability similar to that of crustacean AK. This is significant in allergy diagnosis and the treatment of octopus-allergic disorders.     

Whey protein nanofibrils: the environment-morphology-functionality relationship in lyophilization, rehydration, and seeding

Amyloid-like fibrils from β-lactoglobulin have potential as efficient thickening and gelling agents for food and biomedical applications, but the link between fibril morphology and bulk viscosity is poorly understood. We examined how lyophilization and rehydration affects the morphology and rheological properties of semiflexible (i.e., straight) and highly flexible (i.e., curly) fibrils, the latter made with 80 mM CaCl(2). Straight fibrils were fractured into short rods by lyophilization and rehydration, whereas curly fibrils sustained little damage. This was reflected in the viscosities of rehydrated fibril dispersions, which were much lower for straight fibrils than for curly fibrils. Lyophilized straight or curly fibrils seeded new fibril growth, but viscosity enhancement due to seeding was negligible. We believe that the increase in fibril concentration caused by seeding was counterbalanced by a decrease in fibril length, reducing the ability of fibrils to form physical entanglement networks.     

Isolation and characterization of an oxygen radical absorbance activity peptide from defatted peanut meal hydrolysate and its antioxidant properties

Defatted peanut meal hydrolysate (DPMH) was purified using ultrafiltration, gel filtration chromatography, and high-performance liquid chromatography. A tripeptide with strong oxygen radical absorbance capacity (ORAC) was isolated and identified as Tyr-Gly-Ser by ESI-MS/MS. It was then synthesized to measure its antioxidant properties in different systems. The ORAC value of Tyr-Gly-Ser was 3-fold higher than that of glutathione (GSH), and it displayed a stronger protective effect on linoleic acid peroxidation and H(2)O(2)-induced oxidative injury in rat pheochromocytoma line PC12 cells than GSH (p < 0.05). However, Tyr-Gly-Ser showed negligible DPPH radical scavenging activity, reducing power, and no metal chelating ability. The results suggested that Tyr-Gly-Ser displayed antioxidant activity via the hydrogen atom transfer mechanism, and the Tyr at the N-terminal was the hydrogen donor. The ORAC assay was recommended as a reliable and effective method to measure the antioxidant activity in the course of antioxidant peptide isolation.