Thermodynamics of calcite growth: baseline for understanding biomineral formation     

HH Teng  PM Dove  CA Orme  De Yoreo JJ 《Science (New York, N.Y.)》1998,282(5389):724-727

The complexity of biomineralized structures suggests the potential of organic constituents for controlling energetic factors during crystal synthesis. Atomic force microscopy was used to investigate the thermodynamic controls on carbonate growth and to measure the dependence of step speed on step length and the dependence of critical step length on supersaturation in precisely controlled solutions. These data were used to test the classic Gibbs-Thomson relationship and provided the step edge free energies and free energy barriers to one-dimension nucleation for calcite. Addition of aspartic acid, a common component in biomineralizing systems, dramatically affected growth morphology and altered the magnitude of the surface energy.  相似文献   

Effects of timing and method of application of Penicillium oxalicum on efficacy and duration of control of Fusarium wilt of tomato   总被引：3，自引：0，他引：3  

De Cal  García-Lepe  Pascual  & Melgarejo 《Plant pathology》1999,48(2):260-266

The effects of timing and method of application of Penicillium oxalicum on the control of fusarium wilt of tomato were investigated. Application of P. oxalicum to tomato seedlings in seedbeds reduced disease caused by Fusarium oxysporum f.sp. lycopersici in a growth chamber by 45–49% and in glasshouse experiments by 22–69%. Disease suppression was maintained for 60–100 days after inoculation with the pathogen in the glasshouse. No disease reduction was observed in tomato plants where P. oxalicum was applied to seeds. Treatment with P. oxalicum did not affect the population of F. oxysporum f.sp. lycopersici in the rhizosphere.  相似文献   

Filamentous Intranuclear Inclusion Bodies in Psittacine Birds. A Structural and Ultrastructural Study     

E. Scarlata  J. J. Salguero  J. Hervs  F. Chacon  M De Lara  J. Jahn  J. C. G  . mez-Villamandos 《Zoonoses and public health》1999,46(6):375-380

This paper concerns a disease affecting a group of African grey parrots, which involves intranuclear inclusion bodies composed of filamentous material. The disease was characterized by either sudden death or death within 2–3 days from onset of non-specific symptoms. At necropsy, gross lesions included enlarged liver, mild hepatic congestion and focal necrosis. Samples from five birds were fixed in 10% formol and routinely processed for light and electron microscopy. In four birds, numerous hepatocytes displayed an enlarged nucleus, with peripheral margination of chromatin; the nucleus was partially or wholly filled by a basophilic inclusion body. In the remaining bird, inclusion bodies were acidophilic and completely filled the nucleus; nuclear enlargement was less evident than in the other birds. At ultrastructural examination, and in both types of IIB, nuclei contained looped filaments but no evidence of viral structures. However, virion-like structures were observed in the cytoplasm of some hepatocytes.  相似文献   

The Impact of Atmospheric Deposition of Non-Acidifying Substances on the Quality of European Forest Soils and the North Sea     

Van den Hout  K. D.  Bakker  D. J.  Berdowski  J. J. M.  Van Jaarsveld  J. A.  Reinds  G. J.  Bril  J.  Breeuwsma  A.  Groenenberg  J. E.  De Vries  W.  Van Pagee  J. A.  Villars  M.  Sliggers  C. J. 《Water, air, and soil pollution》1999,109(1-4):357-396

In the pilot study ESQUAD the impact of atmospheric deposition of three heavy metals (cadmium, copper and lead) and two persistent organic pollutants (benzo(a)-pyrene and lindane) on the quality of European soils and seawater has been calculated. Calculations have been made of atmospheric transport and deposition using a detailed emissions database for Europe. This enabled deposition maps to be produced to a resolution of approximately 50 km. The distribution of pollutant concentrations in forest soils was calculated for each grid cell using a database of soil property parameters in Europe. For the North Sea, a model was used to map long-term concentrations in water and sediment, which are due to atmospheric deposition and other, non-atmospheric sources. The model calculations allowed detailed comparisons of deposition fluxes and concentrations of the substances studied with critical loads and environmental quality threshold values, including critical loads. Although significant uncertainties were identified, the study gives insight in how threshold exceedance rates in Europe relate to pollutant type, threshold type, environmental compartment and chemophysical phase (adsorbed, dissolved). For all pollutants and for all compartments exceedances were calculated for at least some of the quality thresholds that were chosen.  相似文献   

Effects of Sewage on the Chemical Composition of Piracicaba River,Brazil     

Martinelli  Luiz A.  Krusche  Alex V.  Vicgoria  Reynaldo L.  De Camargo  Plinio B.  Bernardes  Marcelo  Ferraz  Epaminondas S.  De Moraes  Jorge M.  Ballester  Maria Victoria 《Water, air, and soil pollution》1999,110(1-2):67-79

Water samples were collected from 7 locations along major rivers of Piracicaba River basin for 22 months. The 4 upstream points represent non-polluted sites and the 3 downriver points represent polluted sites. Due to sewage input, concentrations of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), major conservative cations and anions increased significantly in the polluted sites. The major increases were observed for sodium, chloride and sulfate. Nitrate was an exception for this pattern, with similar concentrations between polluted and non-polluted sites. The probable cause was reduction of nitrate to ammonium in the polluted sites, where anoxic conditions prevail. Most of the variables had an inverse correlation with water discharge, especially in the polluted points. The sewage load was diluted by precipitation and surface waters.  相似文献   

Influence of inorganic and organic fertilization on soil microbial biomass, metabolic quotient and heavy metal bioavailability     

L. Leita  M. De Nobili  C. Mondini  G. Muhlbachova  L. Marchiol  G. Bragato  M. Contin 《Biology and Fertility of Soils》1999,28(4):371-376

 We studied the long-term effects (12 years) of municipal refuse compost addition on the total organic carbon (TOC), the amount and activity of the microbial biomass (soil microbial biomass C, B_C and metabolic quotient qCO₂) and heavy metal bioavaiability in soils as compared to manuring with mineral fertilizers (NPK) and farmyard manure (FYM). In addition, we studied the relationships between among the available fraction [Diethylenetriaminopentacetic acid (DTPA) extractable] of heavy metals and their total content, TOC and B_C. After 12 years of repeated treatments, the TOC and B_C of control and mineral fertilized plots did not differ. Soils treated with FYM and composts showed a significant increase in TOC and B_C in response to the increasing amounts of organic C added. Values of the B_C/TOC ratio ranged from 1.4 to 2, without any significative differences among soil treatments. The qCO₂ increased in the organic-amended soil and may have indicated microbial stress. The total amounts of metals in treated soils were lower than the levels permitted by the European Union in agricultural soils. DTPA-extractable metals increased in amended soils in response to organic C. A multiple regression analysis with stepwise selection of variables was carried out in order to discriminate between the influence exerted on DTPA-extractable metals by their total content, TOC and B_C. Results showed that each metal behaved quite differently, suggesting that different mechanisms might be involved in metal bioavailability Received: 31 October 1997  相似文献   

农用运输车可靠性分析评价研究     

郑殿旺  高德  鲁立刚  王耀斌 《农业机械学报》1999,30(1):89-92

以ＹＬ２２０８ＣＷ型四轮农用运输车可靠性试验为依据,参照有关的国家和前机械工业部标准,对该车可靠性进行了分析,计算和评价,并开发了农用运输车可靠性评价计算机系统,提出了提高和改进其可靠性的途径。  相似文献   

细粒棘球蚴细胞系(13G-5)细胞代谢抗原的免疫原性和反应原性   总被引：2，自引：0，他引：2  

陆家海  李德昌  郭中敏  张守竹  冯德元  郭固 《中国兽医学报》1999,(6)

应用培育成功的人源细粒棘球蚴细胞系(13G-5)细胞的天然代谢抗原,接种昆明小鼠,于接种后第14天给免疫小鼠接种人源细粒棘球蚴原头节约1 000 个,于200 d 剖检观察有无包囊形成,病理切片鉴定;并用该抗原作为诊断抗原,使用间接血凝(IHA)、琼脂扩散(AGD)试验,检测临床确诊的细粒棘球蚴病人血清。以多房棘球蚴病人血清、细颈囊尾蚴羊血清及正常人血清作为对照。结果表明,该抗原能使60% 的小鼠获得完全抵抗细粒棘球蚴原头节攻击的能力,未完全获得保护的小鼠形成包囊的数量、大小较对照组明显减少,且为不育囊;使用该抗原IHA 检测31 份血清,阳性24 份,阳性率77.42% ,AGD检测30 份血清,阳性13 份,阳性率43.33% ,2 种方法对多房棘球蚴病人血清和细颈囊尾蚴羊血清及正常人血清不起反应。  相似文献   

Reovirus serology in broiler parents and their progeny and its correlation with performance.     

P De Herdt  R Ducatelle  E Uyttebroek  J Hermans  A Sneep  R Torbeyns 《Avian diseases》1999,43(2):271-278

An intensive vertically integrated monitoring program for broiler breeders and their offspring was set up in a Belgian poultry integration between 1993 and 1997. Serology for anti-reovirus antibodies was performed by enzyme-linked immunosorbent assay on blood samples taken from the broiler parents throughout rearing and production and also on blood samples taken at day-old and at slaughter from the broilers. Furthermore, production parameters of the birds were registered. All data were used two by two in a simple correlation study to calculate the degree to which these variables were linearly correlated. The reovirus antibody pattern indicated frequent field infections breaking through vaccinal immunity in the broiler parents. Under the epidemiologic conditions of this study, high antibody titers in the parents or in the broilers at day-old were significantly correlated with poor feed conversion, increased mortality, increased slaughterhouse condemnation, and low production score in the broilers. These correlations strongly support the view that reovirus infections can be economically important under European conditions of broiler production. Improvement of reovirus vaccines or the vaccination scheme in broiler parents or both may lead to better production results in the broiler offspring.  相似文献   

梅花鹿幼鹿人工培育技术的研究   总被引：3，自引：0，他引：3  

潘庆杰  姜胜 《经济动物学报》1999,3(4):24-27

本试验首先通过幼鹿日粮调配寻求最佳合理的日粮配合,首次制定出了幼鹿发育阶段精料年供量曲线。通过对幼鹿采用直线培育措施,加强饲养管理,取得了显著的效果。其中日增重提高３５ ％ ,初角茸产量提高了３ 倍,头锯茸产量提高了７７－９ ％ ,创造了历史最高产,幼公鹿出生５ 个月开始产茸,幼母鹿培育至１７ 个月即可参加配种,配种准胎率１００ ％ ,仔鹿成活率达到９２ ％ 。  相似文献