Effects of Landfill Gas on Growth and Nitrogen Fixation of Two Leguminous Trees (Acacia Confusa,Leucaena Leucocephala)

A study was made on the effects of landfill gas on ARA (acetylene reducing activity) of nodules of two woody legumes (Acacia confusa and Leucaena leucocephala) widespread on landfill sites in Hong Kong. The effects of the three main components of landfill gas, O₂, CO₂ and CH4, were first measured separately over a 1-hr period. Maximum ARA was found at 20% O₂ (close to atmospheric partial pressure) and ARA decreased as the O₂ decreased in the range of 16–1%. Acacia confusa nodular ARA was significantly inhibited at 30–50% CO₂, but not Leucaena leucocephala nodular ARA. CH₄ had no significant effect on ARA of either species. As the landfill gas concentrations in the landfill topsoil were mostly > 10% O₂ and < 10% CO₂, root nodules should fix N₂ effectively over these ranges of gases. A four-week test was conducted to assess the long-term influence of landfill gas on seedlings of the two legumes. Landfill gas and elevated CO₂ both suppressed their growth and their nodular ARA. Even under the influence of the gases, however, seedlings with nodules formed a higher biomass than seedlings lacking nodules. The growth of the two legumes under actual landfill conditions was investigated by transplanting non-inoculated and pre-inoculated seedlings to two landfill sites in Hong Kong: Junk Bay and Shuen Wan Landfill. After six months, most of the non-inoculated seedlings became infected: Acacia confusa 63 and 70%, Leucaena leucocephala 17 and 89%, respectively, at the test sites. The results indicate that there were free rhizobia at these landfill sites to infect the legumes and they had formed effective nodules to fix N₂ under landfill conditions.     

应用PAPD方法对鸡败血霉形体DNA多态性的研究

用随机扩增多态性ＤＮＡ（ＲＡＰＤ）方法,通过筛选的５个随机引物（ＯＰＨ－０２,ＯＰＨ－０５,ＯＰＨ－０７,ＯＰＨ－１３,ＯＰＧ－１６）,对１４株鸡败血霉形体（ＭＧ）国际标准株和国内分离株进行了ＤＮＡ多态性研究。结果表明,５个引物共产生２１种条带,其中有３个条带分别为２个菌株所特有,扩增产物片段的长度在１５０～４５００ｂｐ之间,所有菌株均有１条共同条带,以ＯＰＨ－０５扩增产物的多态性最丰富。根据样品ＤＮＡ所获得的菌株间相似性指数表明,Ｄ９６０３与Ｄ９６０７相似指数最高,Ｓ６,Ｋ３９１３和Ｄ９６０４三者相互间相似性指数最低。提示ＲＡＰＤ方法可用于霉形体遗传标记的分析。     

美味黑粉菌冬孢子萌发条件的研究

研究了疏亲水界面、温度、pH值和不同物质对美味黑粉菌冬孢子萌发的影响,以探讨美味黑粉菌冬孢子在自然生境条件萌发的适应性。研究结果表明,疏水界面促进美味黑粉菌冬孢子萌发,在疏水的聚苯乙烯塑料培养皿和茭白茎表皮上,萌发率高;冬孢子萌发的最适温度为27～30℃,温度过高或过低均抑制萌发;酸性条件促进冬孢子萌发,最适pH值为3～4;蔗糖促进冬孢子萌发,且以1%浓度最适,但同样浓度的甘露醇、葡萄糖、海藻糖、D-果糖等抑制冬孢子萌发。     

多年生人工牧草“老芒麦”根系层土壤含水率对节水的影响研究

基于浑善达克沙地人工牧草灌溉试验场观测的气象、叶片的蒸腾速率、叶面积指数、有效根系层深度、土壤含水率、土壤蒸发等数据,利用双作物系数法模拟计算了2004、2005年老芒麦的日作物需水量,经与实测的作物蒸腾和土壤蒸发数据对比分析,检验了需水量模拟值与实测值间的一致性,在此基础之上,讨论了老芒麦需水量与产量、光合作用与蒸腾速率、光合作用与根系层土壤含水率的关系,结果表明:对老芒麦来说,从抑制无效蒸腾角度实现节水最直接的方法应该是有效根系层的土壤水分保持在田间持水率的51%~74%。     

Effect of cold-anesthetization rate on blood biochemical parameters and muscle composition during live channel catfish Ictalurus punctatus waterless preservation

Fisheries Science - Cold-anesthetization waterless live fish preservation is considered a promising alternative strategy. This work investigates the effects of temperature chilling rates of 2, 4,...     

Tail Muscle Free Amino Acid Concentration of Pacific White Shrimp,Litopenaeus vannamei,Fed Diets Containing Protein‐bound versus Crystalline Amino Acids

Tail muscle tissue free amino acids (FAA) concentration is reported for subadult (4.3 g) Litopenaeus vannamei fed diets containing only protein‐bound amino acids, crystalline lysine as a supplement to protein‐bound lysine, and only crystalline amino acids (CAA). FAA were determined in shrimp at 0.00, 0.25, 0.5, 1, 2, 4, and 8 h postfeeding. Highest total tissue concentrations of essential amino acids and individual amino acids were typically observed 4 h postfeeding for shrimp fed intact and crystalline lysine‐supplemented feeds. Those shrimp offered diets containing only CAA showed no tissue maxima. Similar uptake patterns for lysine shown by shrimp fed the intact and crystalline lysine‐supplemented diet indicate the potential use of small amounts of crystalline lysine in shrimp feeds.     

Box-Behnken设计优化贵州野生地枇杷总黄酮提取工艺

在各单因素实验基础上,以总黄酮提取率为指标,通过Box-Behnken响应面设计考察乙醇浓度、料液比、提取时间、提取次数对地枇杷总黄酮提取工艺的影响,优化贵州野生地枇杷总黄酮提取工艺。结果表明:地枇杷总黄酮的乙醇回流最佳提取工艺条件的酒精浓度为70%,液固比1∶15,提取时间为30 min,提取次数为3次,地枇杷总黄酮提取率为5.09%。按最优提取条件进行3次验证实验,最终地枇杷总黄酮平均提取率5.13%。本文利用乙醇回流提取地枇杷总黄酮工艺操作简便,稳定可行。     

Transcrytalline structures and crystallization kinetics of Polyarylate/Nylon6 Islands-in-a-Sea conjugate fibers for high performance thermoplastic composite applications

We report the isothermal and non-isothermal crystallization kinetics and associated transcrystalline morphological features of polyarylate(PAR)/nylon6 islands-in-a-sea fibers, where 74 PAR islands serve as reinforcing fibers and nylon6 sea component acts as a semicrystalline matrix in final thermoplastic composites. The temperature-dependent polarized optical microscopic images obtained during a cooling process exhibit that the melt-crystallization is dominated by the interfacial crystallization of nylon6 on the surface of PAR fibers, leading to developing a transcrystalline structure. From the isothermal and non-isothermal melt-crystallization analyses of the islands-in-a sea fiber by using differential scanning calorimetry and the Avrami equation, the overall crystallization rates of the nylon6 sea component in the islands-in-a-sea fiber are found to be highly accelerated by the heterogeneous nucleating effect of the PAR island fibers. In addition, it is revealed that the isothermal and non-isothermal melt-crystallization kinetics of the nylon6 in the islands-in-a-sea fibers consists of two different mechanisms of the primary crystallization owing to the interfacial crystallization and the secondary crystallization due to the bulk crystallization.     

基于ALEPH单册管理系统的图书清点工作——以首都师范大学图书馆为例

图书馆馆藏清点工作是图书馆馆藏管理工作的重要内容,然而由于清点工作的复杂性导致此项工作难以经常开展。现以首都师范大学图书馆图书清点工作的实践为例,介绍了如何利用AIMS系统进行图书清点的方案设计和实际工作实践,并提出了AIMS系统本身存在的局限和问题,为图书馆馆藏清点以及管理工作提供参考。     

抚仙湖北部农田区不同施肥对水稻产量、氮素吸收及利用率的影响

针对抚仙湖北部农田区的蔬菜施肥过量导致土壤养分残余量大,会对后作水稻施肥造成影响的问题,采用田间小区开展不同施肥试验研究。结果表明,砂壤土和粘壤土在施氮量为150~360 kg/hm²范围内,水稻植株氮素积累量随着施氮量的增加而提高,而增加的氮素积累量主要表现在茎叶部位;穗肥施用氮肥可提高籽粒氮素积累量。水稻氮肥吸收利用率和产量,砂壤土以施氮255 kg/hm2时最高,分别为45.1%和10594 kg/hm²;而粘壤土施氮150~360 kg/hm²之间,氮肥吸收利用率为20.9%~22.4%之间,产量为10486~10596 kg/hm2之间;当对砂壤土和粘壤土的水稻穗肥施用氮肥时,水稻氮肥吸收利用率（分别为42.8%、23.5%）和产量（分别为10445 kg/hm²、10564 kg/hm²）最高。水稻的氮素收获指数、氮肥农学利用率、氮肥生理利用率及氮肥偏生产力,均以砂壤土明显高于粘壤土,且随着施氮量的增加而显著下降。蔬菜后作水稻施氮量以150~255 kg/hm²范围为宜,氮肥分基肥50%+分蘖肥30%+穗肥20%施用