Global Dryland Ecosystem Programme (Global-DEP): Australasian consultation report

Journal of Soils and Sediments -     

湖南省某生猪批发市场疫病传播风险评估

为评估湖南省某生猪批发市场猪群疫病的发生风险,找出可能的风险因素,便于提出针对性预防措施,采用自行设计的调查问卷,结合访谈和现场调查,对27户经营户进行了调查,并将调查结果和调运数据相结合进行了疫病传播风险定性评估。结果显示:该市场疫病传入的可能性"高",内部传播的可能性"中等",疫病传出的可能性"高"。生猪调运频次多、数量大,经纪人行为复杂,运输车辆清洗消毒不彻底是可能的风险因素。评估结果提示,应尽量减少经纪人行为影响,重点加强对运输车辆的清洗消毒。     

Effects of different arginine/lysine level on growth performance,body composition and digestive enzyme activity of Macrobrachium rosenbergii

Given the universal presence of antagonism between arginine and lysine, determining the optimal dietary arginine/lysine level is of great importance. In this study, eight diets were formulated to contain different arginine/lysine level, followed by a 9‐week feeding trial with shrimps of 2.10 ± 0.01 cm in length and 0.38 ± 0.02 g in weight to determine the effect of dietary arginine/lysine level on growth performance, body composition and enzyme activity. The results showed that the Diet 6 (arginine/lysine level of 29.4/21.0 g/kg) group had significantly higher weight gain rate, and specific growth rate than the control group and most of the other groups (p < .05) did. Similarly, the retention efficiency of arginine and lysine in the Diet 6 group was significantly higher than the control group and most of the other groups (p < .05). Moreover, most digestive enzymes had higher activity levels in the Diet 6 group, and evident antagonism between dietary arginine and lysine was detected. In summary, dietary arginine/lysine level of 29.4/21.0 g/kg produced the best growth performance, suggesting that a better growth performance in Macrobrachium rosenbergii culture can be obtained by adjusting the dietary arginine/lysine level.     

绿色木霉纤维素酶AS3.3032固态发酵的研究

该研究以麦麸和汽爆蔗渣为主要原料 ,采用绿色木霉AS3 30 32 (Trichodermaviride)固态发酵生产纤维素酶 ,研究了氮源、碳源、表面活性剂、接种方式、培养基含水量、培养温度、培养基起始pH值对绿色木霉产酶活力的影响 .研究结果表明 :①以硫酸铵为氮源 ,其FPA ,CMC ,和 β Gase酶活力均较高 ,每克干曲分别高达 12 2 5FPAU g ,1470 0CMCU g和 119 3β GaseU g ;②碳源以麸蔗比为 3∶2时 ,FPA ,β Gase和CMC酶活力均为最高 ,每克干曲分别高达 138 2FPAU g ,134 6 β GaseU g和 16 0 3 1CMCU g ;③添加 0 1%的Tween 80和 0 5 %～ 0 7%的洗衣粉可分别提高FPA ,β Gase和CMC为 2 3倍、2 8倍、2 3倍和 3 1倍、3 7倍、3 0倍 ;④培养基含水量、培养温度、培养起始pH值分别为 2 5 0 % ,2 8℃和pH3 5 ,产酶活力最高     

NDVI时序相似性对冬小麦种植面积总量控制的制图精度影响

遥感技术获取的区域作物面积与作物面积统计数据间常常存在不一致的问题,这在一定程度上影响了作物分布遥感制图信息的应用.为获得与作物面积统计数据一致的高精度作物分布遥感制图信息,该研究以河北省衡水市武邑县为研究区,以时序Sentinel-2遥感影像生成的归一化差值植被指数(Normalized Difference Veg...     

Mechanisms of phosphate retention by calcite: effects of magnesium and pH

Purpose

Sorption and precipitation of phosphate are important processes in controlling fate of phosphorus (P) in P-fertilized soils, especially those affected by magnesium (Mg) ions.

Materials and methods

The interaction between Mg(II) (0.42 and 8.33 mM) ions and phosphate (0.32 and 6.45 mM) at the calcite–water interface were investigated with various pH values from 6.0 to 12.0, using a combination of sorption envelopes, Fourier transform infrared spectroscopy, and X-ray diffraction.

Results and discussion

Amorphous calcium phosphate, dibasic calcium phosphate dihydrate, and hydroxyapatite are formed at high phosphate concentration (6.45 mM) and high pH (>8.0). The presence of low Mg(II) ion level (0.42 mM) had little effect on phosphate sorption. When Mg(II) ions increased to 8.33 mM, phosphate retention was inhibited in the weak acid condition since incorporation of Mg(II) ions kinetically hinders precipitation resulting in greater solubility of calcium phosphate while high pH favors Mg adsorption to provide more =Mg sites and OH functional groups on the surface of calcite, which enhanced the formation of Mg–P phases. The likely mechanism is attributed to the different surface terminations of calcite sorbed by phosphate at pH?<?8.0 and pH?>?8.0 in the presence of Mg(II) ions.

Conclusions

Our experimental results suggested that soil pH, initial concentration of phosphate, and the presence of Mg(II) ions and calcite play an important role to affect the fate of phosphate in P-fertilized soils.     

牛粪污螺旋挤压式固液分离机优化设计与试验

为优化螺旋挤压式固液分离机工作参数,研究了牛粪尿TS质量分数为10%时,变径螺旋轴分离段锥度、分离筛笼栅条间隙、螺旋轴转速、出料端部压力对机器分离效率、原料的固体去除率和机器能耗的影响。经参数优化和试验验证,在螺旋轴分离段锥度2.68°、分离筛笼栅条间隙1 mm、螺旋轴转速60 r/min、出料端部初始压力3 250 N时,分离效率可达746.18 kg/h,固体去除率可达49.84%,分离后固体的含水率为61%,分离效果较好。     

微生物菌肥与化学肥料配施对盈江省藤生长的影响

为了解不同肥料种类及其施肥量对盈江省藤生长的影响,采用L₉(3⁴)正交试验设计对其2年生幼林进行连续3年的微生物菌肥与复合肥和磷肥配施试验。结果表明,3年中不同因素的各水平组合间苗木的地径、株高、叶片数和冠幅均呈现极显著的差异(P<0.01)。施用复合肥和磷肥总体呈现显著(P<0.05)或极显著(P<0.01)地抑制盈江省藤生长的现象。不同肥料配施试验组合的地径、株高和叶片数均大于对照的相应指标。试验期间,单施微生物菌肥0.3~0.6 g/株即可满足盈江省藤生长的需求。     

狂犬病病毒糖蛋白转基因小鼠的构建研究

将狂犬病病毒糖蛋白ｃＤＮＡ ＢｇｌⅡ（１．６７ｋｂ）片段正向插入ｐＭＴ０１０／Ａ＾＋ＢａｍＨⅠ切点，构建重组质粒ｐＭＴ０１０／Ａ＾＋－Ｒｇｐ，用ＥｃｏＲⅠ＋ＳａｌⅠ对ｐＭＴ０１０／Ａ＾＋－Ｒｇｐ进行双酶切后，回收含有狂犬病病毒糖蛋白ｃＤＮＡ和绵羊ＭＴ启动子的２．７６ｋｂ片段，通过显微注射技术将该片段注入小鼠单细胞受精卵雄前核内，在进行胚胎移植后，获得４４只小鼠，经ＰＣＲ、Ｓｏｕｔｈｅｒｎ杂交及原位     

不同用量白云质石灰石对泥炭pH的调节试验

针对无土栽培中使用的泥炭酸性较强、不适合绝大多数花卉生长这一特点,通过在泥炭中加入不同用量的白云质石灰石,在25℃±3℃的恒温培养箱中进行培养,测定基质pH的变化,从而研究白云质石灰石对栽培基质pH调节的效果及pH与石粉用量的关系.结果表明,泥炭pH的变化主要发生在前5 d(天),到15 d(天)后基本达到稳定状态.白云质石灰石用量与泥炭pHH2O、pHKCL之间呈线性关系,回归方程分别为y=0.1341x 3.9856;y=0.11x 3.8309.