Hydrological studies of Matatilla Reservoir, Uttar Pradesh

Matatilla Reservoir, located in semi arid region, (Lat. 25 degree 15'N and Long. 78 degree 23'E) has an area (at FRL) of 13,893 ha, volume and shore development 0.663 and 1.65, shoreline 73.6 km. Volume and shore development indicate that greater part of the reservoir is shallow, which is a favourable point for fish productivity. Temperature and dissolved oxygen gradually decreased with the increase in depth. Carbon dioxide was absent from the surface but invariably present in the bottom (3.6 ppm) pH remained alkaline (7.2-8.4 ppm) throughout the year. Alkalinity, chloride, calcium, magnesium, hardness and priductivity was maximum in pre-monsoon and minimum in monsoon except for calcium and manganesium in post-monsoon. Phosphate, nitrogen and ammonical nitrogen were found in traces. These variations may be due to influx and outflow of water and use of reservoir water for multipurpose activities.

氮素添加对内蒙古羊草草原净氮矿化的影响

　　氮素作为陆地生态系统生产力主要的限制因子，对生态系统过程的调控有着重要的意义。净氮矿化是有机氮素到无机氮素的转变过程，该过程决定了土壤氮素的可利用性。准确估计土壤的供氮能力可以为确定最佳施肥量和施肥时间提供理论依据，并将影响着土地的可持续发展和管理政策。氮矿化潜力N0被定义为在最适温度和湿度下，土壤氮素在无限时间内所能矿化的最大量。由于氮矿化潜力是土壤供氮能力很好的指示值，所以对氮矿化潜力的研究能够使我们更好地了解土壤的氮素矿化动态和其供氮潜力。 　　为更好地了解天然草原氮素矿化对全球氮沉降背景以及草原施肥管理模式的响应，我们从2000年起在内蒙古羊草草原开展了长期的氮素添加实验，分别设置对照(N0)、添加5g N•m-2(N1.75)、30g N•m-2(N10.5)和80g N•m-2(N28)四个氮肥添加梯度以及对照(control)、添加100g有机肥•m-2(O100)、添加500g有机肥•m-2(O500)、添加1000g有机肥•m-2(O1000)四个有机肥添加梯度。氮肥添加在相邻并同时进行施肥的两个生态系统类型中展开，即成熟羊草草原（A区，1979年围封）和退化的羊草草原（B区，1999年围封），有机肥添加也同时在与之相邻的C区中展开（C区的土地利用历史与B区一致）。 2002年和2006年，从A、B区中进行氮肥处理后的土壤取样；有机肥处理的土壤样品从2002年C区中获得。土样在最佳温度(25℃)和湿度(60%田间持水量（WHC）)下进行了5周室内培养，并用阶段淋溶方法来测定氮肥添加和有机肥添加对土壤氮矿化动态的影响。 　　氮肥添加显著降低了土壤的pH值，但累积氮矿化量与土壤pH值、有机碳、全氮均没有显著的相关性。在两个区内，氮素添加都显著改变了土壤的累积氮矿化量。最高氮素处理N28相对应于最低的累积氮矿化量，而低氮素处理N1.75却使得累积氮矿化量最高。同时，在N0和N1.75处理中硝态氮的含量高于铵态氮，但在N28处理中却表现出相反趋势。实验还表明大多数氮素添加强度处理在A区比B区有更高的土壤累积氮矿化量。 　　有机肥添加也显著改变了土壤5周内的累积氮矿化量，并且累积氮矿化量随有机肥添加强度的升高而显著增加。培养5周末时土壤的累积铵态氮的含量与有机肥施加强度之间并没有相关性，但是累积硝态氮的含量有随着有机肥施加强度的上升而增加的趋势。 　　基于前5周土壤培养所得到的结果，我们选择了氮肥添加的N0，N1.75， N28处理以及有机肥添加的control、O100、O1000处理继续进行了长达15周的培养。培养数据与描述土壤氮矿化动态的一级动力学模型--first-order kinetics: Nm=N0（1－exp(-kt)）拟合良好( R2=0.893～0.97)。无论是氮肥添加还是有机肥添加都显著增加了土壤的氮矿化潜力N0，并且N0随着氮肥或者机肥添加强度的增加而增加。对于氮肥处理的土壤来说， N0与氮矿化速率常数k之间反向相关，但是在有机氮处理的土壤中N0与k之间却没有相关性。总的结果显示，经有机肥添加的土壤比经氮肥添加的土样有着更大的氮矿化潜力N0值以及氮矿化速率常数k值，较大的k值暗示着土壤氮素较快的周转速率。

Trawling pull exerted by a trawler: a method of estimation from propeller dimensions and its comparison with sea measurements

The proper matching of the pull exerted by a trawler and the size of trawl is important for maximizing the catching efficiency. The available pull is more dependent on the propeller and its working conditions than the installed engine power. The normal practice is to directly connect net size to the installed power in the boat by formulae without reference to the prope1ler dimensions or the available trawling pull and this is not adequate to find out the optimum combination. By the method outlined in this paper, the accurate calculation of trawling pull is possible by taking into account only the propeller diameter, pitch and r. p. m. The predictions by the method are compared for trawlers with powers between 30 and 60 hp and agreement is found to be within + 5%. The power absorbed by the propeller in trawling condition can also be calculated by this method for checking whether the engine is being overloaded.

Preservation of fish by freezing and glazing. Pt. 2. Keeping quality of fish with particular reference to yellow discolouration and other allied organoleptic changes on prolonged storage

Organoleptic observations of quick, slow and block frozen, glazed and stored fish were recorded at regular intervals. Glazing was renewed at intervals of four weeks. Development of yellow discolouration in the case of white pomfret was followed. Keeping quality of glazed fish was better than unglazed frozen fish. Yellow discolouration could be controlled by ascorbic acid for 42 months and by a mixture of sodium chloride and glucose for 52 months.

不同基因型小麦（Triticum aestivum）京411与小偃54抗光氧化特性及其机理的比较研究

对两种不同基因型小麦京411（北京地区高产小麦品种）和小偃54（在生产上已应用二十年的优良品种）幼苗及旗叶光抑制特性进行了比较研究，着重探讨了它们抗光氧化的差异及其机理，主要结果如下： 1. 强光条件下，同京411相比小偃54能保持较高的光合色素含量和放氧速率。其DCPIP光还原活性也较高。 2. 光谱特性分析表明，强光胁迫下小偃54在红区及蓝区的特征性吸收峰及F683荧光发射峰下降的幅度明显小于京411相应峰位的下降。 3. 色素蛋白复合物分析表明，强光条件下，京411色素蛋白复合物中LHCII聚合体大量的解聚，而小偃54在强光条件下仍能保持较高比例的LHCII聚合体。这可能在一定的程度上有利于小偃54在强光下维持较强的激发能耗散的能力。 4. 多肽SDS-PAGE分析表明，强光对不同基因型小麦中同PSII光抑制敏感性有关的两个外周蛋白23kD和17kD的影响不同。光抑制明显地降低了京411的23kD和17kD的含量，而对于小偃54中这两个外周蛋白23kD和17kD的影响不大。强光条件下小偃54旗叶PSII颗粒中捕光色素蛋白27kD含量提高，而京411捕光色素蛋白27kD含量明显的下降。 5. 上述结果表明，西北地区的优良小麦品种小偃54同北京地区的高产品种京411相比更耐强光的胁迫，其抗光氧化的能力较强。 6. 进一步分析表明，同京411相比，小偃54抗光氧化的主要原因是其不仅含有较大的叶黄素循环的色素库，而且在强光下能维持高的VDE酶活性及高水平的叶黄素循环的脱环化水平。 7. 叶黄素循环色素在两个小麦品种类囊体膜色素蛋白复合体中的分布存在差异，抗光氧化的小偃54大部分的VAZ分布在PSII上，其中绝大部分集中在LHCII聚合体上。LHCII上VAZ的集中分布可能有利于在强光下对过多光能的耗散，减少过多激发能对PSII的损伤。 8. 类囊体膜流动性分析表明，叶黄素循环参与了对类囊体膜流动性的调整，对维持强光下抗光氧化品种小偃54的类囊体膜相对稳定起重要作用。 9. 依赖于叶黄素循环的热耗散是抗光氧化品种小偃54的一个主要的光保护途径。

Field emission from tetrahedrally bonded amorphous carbon

The field emission behaviour of a series of Tetrahedrally Bonded Amorphous Carbon (ta-C) films has been measured. The films were produced using a Filtered Cathodic Vacuum Arc System. The threshold field for emission and current densities achievable have been investigated as a function of sp3/sp2 bonding ratio and nitrogen content. Typical as-grown undoped ta-C films have a threshold field of order 10-15 V/μm and optimally nitrogen-doped films exhibit fields as low as 5 V/μm. The emission as a function of back contact and front surface condition has also been considered and shows that the back contact has only a minor effect on emission efficiency. However, after etching in either an oxygen or hydrogen plasma, the films show a marked reduction in threshold field, down to as low as 2-3 V/μm, and a marked improvement in emission site density.

多路温度信号预处理电路（2）

本实用新型涉及一种计算机控制的、用于温度传感器信号采集与处理的、具有多个信号采集与处理通道的前端电子设备。主要用于大型多测量点温度自动监测与控制系统。一种多路温度信号预处理电路，包括有机箱，多个温度信号输入，基准电压产生电路，其主要特点包括有多个输入电路与其对应的多个温度信号输入、放大电路连接；放大电路连接于多路输出调制电路，多路输出调制电路输出信号；基准电压产生电路与输入电路的输入端连接；输入电路的输出端连接放大电路进而与多路输出调制电路连接或输入电路的输出端连接参比端（冷端）信号处理电路并进而与多路输出调制电路连接，两种连接方式采用跳线器／开关选择设置；计算机控制端连于多路输出调制电路。本实用新型适用性强，是一种既可以用于采集处理热电偶信号，也可以用于采集处理热电阻信号的前端设备；集成度高，单机包含通道数多；实行多路同时采集处理，处理速度快。