Feeding trials were conducted to determine the dietary level of yeast extract (YE) for replacing dietary fish meal for evaluating whether yeast extract was superior to intact yeast as an alternative protein source for shrimp Litopenaeus vannamei. The basal diet (control, D0, containing 25% fish meal), was compared with five isonitrogenous and isoenergetic experimental diets [replacing 15% (D15), 30% (D30), 45% (D45), 60% (D60) or 100% (D100) of the fish meal in the basal diet with IYE]. The digestibility, growth and muscle composition of the shrimp were measured. The results showed that all replacement treatments displayed higher apparent digestibility of crude protein than did the control. The trypsinase activity in shrimp hepatopancreas increased significantly, whereas lipase activity decreased as the amount of dietary YE increased. The shrimp treated with D30 diet displayed the highest amylase activity in hepatopancreas. There was no significant difference in the weight gain (WG) and survival of shrimp between the control and the YE replacement treatments. Feed conversion ratio (FCR) increased as the dietary YE increased, and the FCRs of the D60 and the D100 treatments were significantly higher than that of the control (P<0.05). The growth performance among the treatments was closely related to the similarity of the essential amino acids in the diets. There was no significant difference in muscle composition of the shrimp between control and other treatments. In conclusion, up to approximately 45% of the fish meal in shrimp diet can be replaced by yeast extract in the presence of supplemental fish oil, phosphorus and calcium.

为探明使用经氨基酸平衡后的酵母提取物替代鱼粉对凡纳滨对虾消化机能的影响,分别用酵母提取物替代饲料中15％(B)、30％(C)、45％(D)、60％(E)和1OO ％(F)的鱼粉,配制6种等氮、等能的试验饲料投喂凡纳滨对虾(6.328±0.630 g),以鱼粉含量为25％的饲料为对照组(A).饲养7d后开始收集粪便,测定凡纳滨对虾对饲料的表观消化率.养殖试验结束后,研究酵母提取物替代鱼粉对凡纳滨对虾消化酶的影响.试验结果:凡纳滨对虾对各组饲料均具有较高的干物质表观消化率(77.96％ ～81.21％)和粗蛋白表观消化率(87.19％ ～92.82％);各替代组饲料的表观消化率均高于对照组,其中C、E和F组的干物质表观消化率显著高于对照组(P＜0.05),粗蛋白表观消化率随酵母提取物用量的增加而显著增加(P＜0.05)；凡纳滨对虾肝胰腺中类胰蛋白酶的活性随饲料中酵母提取物用量的增加而显著升高(P＜0.05),脂肪酶的活性随饲料中酵母提取物用量的增加而显著降低(P＜0.05)；肝胰腺中淀粉酶活性最高的为C组；各替代组凡纳滨对虾的肠胰蛋白酶活性均高于对照组.结果表明,以氨基酸平衡酵母提取物替代饲料中的鱼粉可以提高凡纳滨对虾对饲料的消化机能.

Based on analysis of influcing factors on slope stability at the right bank of the Xihe River,some treatment schemes are recommended in this paper through calculation of slope stability by simplified Bishop method.

The basal diet(A) contains 25% fish meal as control,and four isonitrogenous isoenergic yeast extract experiment diets,which substituted 15%(B),30%(C),45%(D) and 60%(E) fish meal in basal diet,were fed to the Litopenaeus vannamei(7.50±0.13) g respectively for 42 d,then superoxide dismutase(SOD) activity and lysozyme(LSZ) activity in haemolymph and the expressions of lysozyme mRNA and Toll receptor mRNA in gill were detected.The shrimp were also challenged with Vibrio alginolyticus.The results showed that: LSZ activity in haemolymph in 15% group was significantly higher than that of control(P0.05).There was no significant difference of SOD activity in haemolymph,the expressions of lysozyme mRNA and Toll Receptor mRNA in gill between alternative groups and control group(P0.05).The cumulative mortality of 60% group at 24 h and 48 h was significant higher than that of control(P0.05),and there was no significant difference of cumulative mortality between alternative groups and control group at 72 h and 96 h(P0.05).It is therefore suggested that yeast extract can replace 45% fish meal of the diets without affecting immunity and vibrio-resistant ability of the shrimp.

Experiments were conducted to determine copper accumulation,SOD and lysozyme activities,immune-related genes(Toll receptor mRNA and Lysozyme mRNA) expression level and Vibrio-resistant ability of white shrimp Litopenaeus vannamei fed the diet with different copper levels(via adding copper methionine 0,30 and 50 mg Cu/kg) for 7d,14d and 21d,respectively.The results indicated that the copper content in hepatopancreas of shrimp significantly increased(P0.05) with increasing dietary copper and feeding time.Copper content in muscle was always significantly lower than that in hepatopancreas(P0.05).There was no significant difference in lysozyme activities in hepatopancreas,muscle and haemolymph of the shrimp among different copper treatments(P0.05),although SOD activity of the shrimp was affected by dietary copper level as well as feeding time.The SOD activities in muscle,haemplymph and hepatopancreas of the shrimp treated with 30 mg Cu/kg diet for 21d were significantly higher than those of the shrimp treated with 50 mg Cu/ kg and 0 mg Cu/kg diets.The dietary copper level did not affect the lysozyme mRNA expression level in shrimp’s gills,but it significantly affected the Toll receptor mRNA expression level in shrimp’s gills(P0.05).The Toll receptor mRNA expression level in shrimp’s gills increased significantly(P0.05) with an increasing dietary copper for 7d(P0.05).While the shrimp treated with 30 mg Cu/kg diet showed the highest Toll receptor mRNA expression level in gills for 14d and 21d.The shrimp treated with 50 mg Cu/kg diet for 7d or with 30 mg Cu/kg diet for 14d displayed the largest half lethal time and complete lethal time when the shrimp were artificially infected with Vibrio alginolyticus.It is therefore suggested that dietary copper level affected not only the accumulation of copper in shrimp tissues,but also the SOD activity and Toll receptor mRNA expression level of the shrimp and finally affected the Vibrio resistance of the shrimp.

The Baotaliang slump deformed mass is situated on a Nanjiang River right bank steep slope in the Caicun village,Chengguan Township,Zhenping County,Shaanxi Province.The slump mass was first found in 1987,and has not been obviously deformed until January,2008.The deformation was started from 1st of February,2008,on 23rd of February,the collapsed face width of slump deformed mass front along the riverside road was increasing from original meters to 60~70m and stretched to upper part of the steep slope,the slope collapsing ceaselessly,and fully interdicted riverside road.Emergency deloading has been carried out during March and April,and then no longer large deformation happened afterwards.Based on detailed description of slump mass deformation features and degree of crushing,considered that the slump mass has presented spall off or disintegration,poor binding force between fragments,and belongs to large type slump mass.Multiple methods including drilling,prospect pit,shallow seismic prospecting,Rayleigh wave test and indoor tests,analyzed and identified configuration,deformation state and boundary of the deformed mass,gave deformation structural plane and computing parameters,and took the parameters carried out stability checking computations.The result has demonstrated that the I―I and III―III sections of slump mass stand in understable state,while the II―II section in stable state,as a whole in understable state.The study result has been verified in July 2009 slump deformed mass rejuvenated deformation.

Experiments were conducted to study the effects of dietary zinc supplementation on the immune gene expression and immunity and disease-resistant ability of white shrimp(Litopenaeus vannamei).The shrimp were fed with 3 zinc methionine diets(supplemented at 0,50,150 mg Zn/kg diet respectively)respectively for 14 days.Then the expressions of Toll Receptor mRNA and lysozyme mRNA in gill and superoxide dismutase(SOD)activity and lysozyme(LSZ)activity in hepatopancreas,muscle and haemolymph were assayed respectively.The shrimp treated with different zinc diets were also challenged with Vibrio alginolyticus.The results showed that the zinc levels in hepatopancreas and muscle of shrimp significantly increased(P0.05)as the dietary zinc increased.While the hepatopancreas accumulated more zinc than muscle.Compared to those of the shrimp in 0 mg Zn/kg and 150 mg Zn/kg treatments,the expressions of Toll receptor mRNA and lysozyme mRNA in gill of the shrimp in 50 mg Zn/kg treatment were significantly up-regulated.The lysozyme activities in muscle,hepatopancreas and haemolymph of the shrimp in 50 mg Zn/kg treatment were significantly higher than those in 0 mg Zn/kg treatment(P0.05).The SOD activities in hepatopancreas and haemolymph of the shrimp in 50 mg Zn/kg and 150 mg Zn/kg treatments were also higher than those in 0 mg Zn/kg treatments(P0.05).While the SOD activity in muscle of the shrimp treated with 150 mg Zn/kg was significantly higher than those treated with 0 mg Zn/kg and 50 mg Zn/kg respectively.The half lethal time and complete lethal time for the shrimp in 50 mg Zn/kg treatment were longer than those in 0 mg Zn/kg and 150 mg Zn/kg treatments after being challenged with V.alginolyticus.It is therefore suggested that compared to those in 0 mg Zn/kg and 150 mg Zn/kg treatments,the shrimp fed the diets added 50 mg Zn/kg(the content of zinc in diet was 73.25 mg Zn/kg)had improved immunity and Vibrio-resistant ability.

在强夯法处理地基的技术参数的设计中,夯点间距的取值和布置形式是强夯法的主要参数,直接关系到强夯后的加固效果、施工效率和经济效益。本文介绍了目前常用的强夯布点间距形式,及确定夯间距大小的依据,比较了不同布点形式的适用情况及利弊。

Through analysis of prestressing force steel,it proposes the method of calculating prestressing force steel with section multiply and similar solution,so as to solve the uncertain problems for present cave-bridge construction.

Based on analysis of the general damage phenomena in bridge deck,the paper elaborates on it from the perspective of vehicle load and brings up calculation method for the depth of cement concrete bridge deck,solving the deck fissure problems caused by wheel load.

质量是设计产品的生命,强调设计质量,强调系统控制,强调过程控制在建设工程设计中的应用,以达到提高设计产品质量的目的。并提出了具体的设计要求。

In order to obtain the effects of polishing parameters on the surface profile of silicon wafer,the kinematical equation on a pendulum polisher is established according to the transformation of coordinate system.Base on kinematical equation and Preston equation on material removal rate,using the method of Monte Carlo,the trajectory of the abrasive grit cutting and the friction distance on the silicon wafer are numerically simulated,and the effects of the rotational speed of the polishing disk,the amplitude and initializing angle of swing arm on the trajectory and the friction distance have been discussed,the simulative results show that there are optimal polishing parameters,which can make the distribution of material removal rate more uniformity and the trajectory better on wafer surface.

The Baotaliang landslide mass in Zhenping County formed in 1987,on which in February 2008,intense deformation occurred,resulting in the increase of fissures from 1～2 to more with the longest fissure over 100 m and a width about 1.2 m.Most of the fissures linked each other with a visible depth about 2m,the largest relative displacement about 1.6m and slump depth about 1.2m.The width of slump surface at the front margin of slump mass increased from original several meters to 60～70m and extended upward to the top of cliff.The volume of collapsed accumulation expands from several hundreds cubic meters to several thousands cubic meters.The deformation of the landslide mass slowed down till to 3rd of May.In this article,the genesis of the landslide mass is analyzed based on geology,tectonics,landform,geomorphology,hydrogeology,and human engineering and climate changes.