Biodegradable PASP can effectively inhibit nitrification,moderate NH3 emission,and promote crop yield

Polyaspartic acid (PASP) is a low-cost, environmentally friendly, and multifunctional polymer material. The knowledge regarding the effects of PASPs, especially the PASPs with a different molecular weight (MW), on nitrogen use efficiency (NUE), ammonia (NH₃) volatilization and nitrous oxide (N₂O) emission in crop fields is scarce. In this study, maize pot experiments were conducted to evaluate three types of PASPs with different MW. Five treatments were designed: (1) application of chemical phosphorus (P) and potassium (K) fertilizer (PK), (2) PK plus urea (NPK), (3) NPK plus PASP-1 (PASPT1, MW: 5517), (4) NPK plus PASP-2 (PASPT2, MW: 6934), and (5) NPK plus PASP-3 (PASPT3, MW: 7568). The yield indicators of crop height, straw dry weight and 100-grain weight showed that PASP application improved the crop growth. In PASP3, NUE reached 46.1%, almost double of that in NPK (28.6%). Moreover, there were significantly less N losses in the forms of NH₃ volatilization and NO₂ emission following PASP amendment than regular urea application. Another positive impact revealed that PASP inhibited the transformation of NH₄⁺-N to NO₃^–N. Among the three PASPs, PASP-3 with the highest MW overall presented optimal effects, implying that MW was a major driving factor for PASP performance on maize production.     

Au20: a tetrahedral cluster

Photoelectron spectroscopy revealed that a 20-atom gold cluster has an extremely large energy gap, which is even greater than that of C60, and an electron affinity comparable with that of C60. This observation suggests that the Au20 cluster should be highly stable and chemically inert. Using relativistic density functional calculations, we found that Au20 possesses a tetrahedral structure, which is a fragment of the face-centered cubic lattice of bulk gold with a small structural relaxation. Au20 is thus a unique molecule with atomic packing similar to that of bulk gold but with very different properties.     

12MCP延缓观赏植物衰老的研究与应用

 1-MCP (1 - 甲基环丙烯) 是一种新型乙烯作用抑制剂, 能有效地抑制内源和外源乙烯对植物的作用, 延缓乙烯诱导的器官衰老和脱落。本文综述了12MCP的作用机理和在观赏植物上的研究与应用现状以及最新进展。     

不同类型土壤的含钙量与苹果的钙素营养

分析了山东省棕壤、褐土、潮土、砂姜黑土和盐碱土果园的土壤理化性状,取样测定了上述土壤红富士苹果的果实含钙量。结果表明,除盐碱土外,土壤有效性钙含量高低顺序是:砂姜黑土>褐土>潮土>棕壤;果实中含钙量高低的排序同上。土壤交换性钙含量与果实含钙量呈显著正相关。栽培红富士苹果的土壤Ca/Mg比值为8-16、N/Ca比值9-18较适宜。棕壤栽培红富士苹果应增施钙肥,并减少氮素化肥的施用量,以降低N/Ca比值。     

钙蛋白酶抑制蛋白与肉嫩度相关性

钙蛋白酶蛋白系统是影响肌肉生长和宰后肉嫩化的一个重要因素,主要由钙蛋白酶(μ-calpain和m-cal-pain)、钙蛋白酶抑制蛋白(calpastatin,CAST)及骨骼肌特异性钙蛋白酶(muscle specific calpain,P94)组成,钙蛋白酶抑制蛋白是一种内源性专一抑制钙蛋白酶(calpain)活性的蛋白,参与了调控肌原纤维蛋白的降解并在其中发挥了关键作用。本文概述了钙蛋白酶系统、钙蛋白酶抑制蛋白的结构、功能及其对提高肉嫩度的作用。     

苹果果实酸/低酸性状的SSR分析

 以91株‘东光’和‘富士’的正反交F₁ 代群体为试材, 测定了成熟果实可滴定酸含量和果实不同发育阶段苹果酸含量的变化, 从表型上分析了苹果酸的遗传规律。利用140对共显性遗传的SSR引物对高酸和低酸个体群体分离分析, 筛选到一个与果实酸/低酸性状连锁的标记SDY085, 遗传距离为8.89 cM, 表型分析和标记分析都表明苹果果实酸/低酸性状由一对主效基因Ma/ma控制, 并且Ma对ma为完全显性, 而酸个体中苹果酸的连续分布则是加性多基因作用的结果。     

东北民猪、哈尔滨白猪在发情期和配种后血液生化常值变化的研究

采用Ｆｏｌｉｎ－吴宪法、比色法、微量消化定氮法和醋纤薄膜电泳法分别测定了东北民猪和哈白猪发情期和配种后的血液糖量、血清总脂、血清总蛋白和血清蛋白含量．结果说明：哈白猪发情情与配种后生化常值比较差异皆不显著；东北民猪除γ－球蛋白和β－球蛋白差异显著外，其它皆不显著。东北民猪、哈白猪比较，发情期生化指标差异皆不显著；配种后生化常值除清蛋白和γ－球蛋白外，其它皆无显著差异。     

膨润土用于反刍动物的饲料添加剂

本文就产自新疆哈密的膨胀润土进行了全面的岩石学和矿物学研究。采用红外光谱，Ｘ－射线衍射分析、化学全分析等手段，对其矿物成分，微量元素、稀土元素、物化性能等方面做了全面测试分析，结果表明：该膨润土为质地优良的钠基膨润土，可作为饲料工业的原料矿产，尤其是反刍动物的饲料添加剂效果最佳。     

在我国发生的甜菜坏死黄脉病毒病

 1978年以来,在内蒙包头、呼和浩特等地发现了一种甜菜新病害。地上部表现叶片黄化、枯斑坏死、沿脉黄化坏死等症状;地下部表现次生侧根异常增生。根据鉴别寄主的症状,病株根部多粘菌(Polymyxa betae)的寄生和病毒形态及粒子长度分布特征确定内蒙所发现的这种新病害即国外报道的由Polymyxa betae传带的甜菜坏死黄脉病毒所致的甜菜丛根病。     

CAD在建筑设计业中的利与弊

本文作者从自身建筑设计行业角度研讨CAD在建筑设计工作应用中的利弊,客观地反映了CAD在实际工作中的使用情况,对CAD在普及应用过程中应把握的问题提出一定的见解。