Assessment of In Situ Immobilization of Lead (Pb) and Arsenic (As) in Contaminated Soils with Phosphate and Iron: Solubility and Bioaccessibility     

Yanshan Cui  Xin Du  Liping Weng  Willem H. Van Riemsdijk 《Water, air, and soil pollution》2010,213(1-4):95-104

The effect of in situ immobilization of lead (Pb) and arsenic (As) in soil with respectively phosphate and iron is well recognized. However, studies on combined Pb and As-contaminated soil are fewer, and assessment of the effectiveness of the immobilization on mobility and bioaccessibility is also necessary. In this study, a Pb and As-contaminated soil was collected from an abandoned lead/zinc mine in Shaoxing, Zhejiang province of China, which has been treated with three phosphates, i.e., calcium magnesium phosphate (CMP), phosphate rock, and single super-phosphate (SSP) for 6 months in a field study. The ferrous sulfate (FeSO₄) at 20 g kg^?1 was then amended to the soil samples and incubated for 8 weeks in a greenhouse. The solubility and bioaccessibility tests were used to assess the effectiveness of the in situ immobilization. The result showed that phosphates addition decreased the concentrations of CaCl₂-extractable Pb; however, the concentrations of water-soluble As increased upon CMP and SSP addition. With the iron addition, the water-soluble As concentrations decreased significantly, but CaCl₂-extractable Pb concentrations increased. The bioaccessibility of As and Pb measured in artificial gastric and small intestinal solutions decreased with phosphate and iron application except for the bioaccessibility of As in the gastric phase with SSP addition. Combined application of phosphates and iron can be an effective approach to lower bioaccessibility of As and Pb, but has opposing effects on mobility of As and Pb in contaminated soils.  相似文献   

Effect of early training on the jumping technique of horses     

Santamaría S  Bobbert MF  Back W  Barneveld A  van Weeren PR 《American journal of veterinary research》2005,66(3):418-424

OBJECTIVE: To investigate the effects of early training for jumping by comparing the jumping technique of horses that had received early training with that of horses raised conventionally. ANIMALS: 40 Dutch Warmblood horses. PROCEDURE: The horses were analyzed kinematically during free jumping at 6 months of age. Subsequently, they were allocated into a control group that was raised conventionally and an experimental group that received 30 months of early training starting at 6 months of age. At 4 years of age, after a period of rest in pasture and a short period of training with a rider, both groups were analyzed kinematically during free jumping. Subsequently, both groups started a 1-year intensive training for jumping, and at 5 years of age, they were again analyzed kinematically during free jumping. In addition, the horses competed in a puissance competition to test maximal performance. RESULTS: Whereas there were no differences in jumping technique between experimental and control horses at 6 months of age, at 4 years, the experimental horses jumped in a more effective manner than the control horses; they raised their center of gravity less yet cleared more fences successfully than the control horses. However, at 5 years of age, these differences were not detected. Furthermore, the experimental horses did not perform better than the control horses in the puissance competition. CONCLUSIONS AND CLINICAL RELEVANCE: Specific training for jumping of horses at an early age is unnecessary because the effects on jumping technique and jumping capacity are not permanent.  相似文献   

When can a veterinarian be expected to detect classical swine fever virus among breeding sows in a herd during an outbreak?   总被引：1，自引：0，他引：1  

Engel B  Bouma A  Stegeman A  Buist W  Elbers A  Kogut J  Döpfer D  de Jong MC 《Preventive veterinary medicine》2005,67(2-3):195-212

The herd sensitivity (HSe) and herd specificity (Hsp) of clinical diagnosis of an infection with classical swine fever (CSF) virus during veterinary inspection of breeding sows in a herd was evaluated. Data gathered from visits to herds during the CSF outbreak in 1997-1998 in The Netherlands were used for the analysis. Herds were visited one or more times by the same or by different veterinarians. On the basis of the veterinarians' reports, each visit was coded as 0 (negative clinical diagnosis) or 1 (positive clinical diagnosis). The HSe for clinical diagnosis of CSF was modelled as a function of days elapsed since introduction of the virus. The moment of introduction of the CSF virus in the CSF-positive herds was unknown, so for each herd, a probability distribution for the unknown number of days since introduction was derived from serum samples collected at depopulation. The information from the reports of the veterinarians and from the test results of the serum samples at depopulation was combined in a Bayesian analysis. Data from CSF-negative herds were analysed to estimate HSp of clinical diagnosis of CSF. The HSe of clinical diagnosis was 0.5 at 37 days after virus introduction (95% CI: 31, 45) and reached 0.9 at 47 days after virus introduction (95% CI: 41, 54). The estimated herd specificity was 0.72 (95% CI: 0.64, 0.79). Dependence of HSe and HSp on characteristics of the veterinarians and the herds also was studied. Specialisation of the veterinarian significantly, although not markedly, affected the HSe.  相似文献   

Evaluation of a new antibody-based enzyme-linked immunosorbent assay for the detection of bovine leukemia virus infection in dairy cattle.     

Gustavo E Monti  Klaas Frankena  Bas Engel  Willem Buist  Héctor D Tarabla  Mart C M de Jong 《Journal of veterinary diagnostic investigation》2005,17(5):451-457

The objective of this study was to validate a new blocking enzyme-linked immunosorbent assay (ELISA) (designated M108 for milk and S108 for serum samples) for detecting bovine leukemia virus (BLV) infection in dairy cattle. Milk, serum, and ethylenediaminetetraacetic acid-blood samples were collected from 524 adult Holstein cows originating from 6 dairy herds in Central Argentina. The M108 and S108 were compared with agar gel immunodiffusion (AGID), polymerase chain reaction and a commercial ELISA. Because there is currently no reference test capable of serving as a gold standard, the test sensitivity (SE) and specificity (SP) were evaluated by the use of a latent class model. Statistical inference was performed by classical maximum likelihood and by Bayesian techniques. The maximum-likelihood analysis was performed assuming conditional independence of tests, whereas the Bayesian approach allowed for conditional dependence. No clear conclusion could be drawn about conditional dependence of tests. Results with maximum likelihood (under conditional independence) and posterior Bayes (under conditional dependence) were practically the same. Conservative estimates of SE and SP (with 95% confidence intervals) for M108 were 98.6 (96.7; 99.6) and 96.7 (92.9; 98.8) and for S108 99.5 (98.2; 99.9) and 95.4 (90.9; 98.1), respectively. The ELISA 108 using either milk or serum to detect BLV-infected animals had comparable SE and SP with the official AGID and a commercial ELISA test, which are currently the most widely accepted tests for the serological diagnosis of BLV infection. Therefore, ELISA 108 can be used as an alternative test in monitoring and control programs.  相似文献   

A simulation of Johne's disease control     

Groenendaal H  Nielen M  Jalvingh AW  Horst SH  Galligan DT  Hesselink JW 《Preventive veterinary medicine》2002,54(3):225-245

A dynamic and stochastic simulation model (the "JohneSSim model") was developed to evaluate the economic and epidemiological effects of different strategies for control of paratuberculosis in dairy herds. Animals occupy one of the six defined infection states; the spread of Johne's disease is modeled with five infection routes. Many different dairy farm situations can be simulated. Control strategies that can be simulated are: (1) test-and-cull; (2) calf hygiene management; (3) vaccination and (4) grouping of animals. Losses are caused by: (1) reduced milk production; (2) diagnosis and treatment costs; (3) lower slaughter value of cows and (4) sub-optimal culling. The benefits were calculated as reduction in the losses caused by Johne's disease; the costs of each strategy were calculated on the basis of actual costs of each item; and net present value (NPV) was calculated as benefits minus costs. Herd and prevalence data from The Netherlands and Pennsylvania, USA were used. In both situations, a low true mean prevalence within 20 years could be reached only when all calf management tools were applied. The Dutch control program (PPN) was on average economically attractive (with or without labor costs, the average NPV was Euro 1183 and 12,397, respectively). In Pennsylvania, contract heifer rearing and improved calf hygiene reduced the prevalence effectively and had large economic benefits (US$ 43,917 for 20-year period) if the calves were sent to the heifer facility while very young. Validation with data from 21 infected Dutch dairy farms (as well as face-validation: comparison of the results of the JohneSSim model with experiences of Johne's experts) supported the basic assumptions in the model.  相似文献   

Applications of a cell culture system for studying the interaction of Anaplasma marginale with tick cells     

Blouin EF  de la Fuente J  Garcia-Garcia JC  Sauer JR  Saliki JT  Kocan KM 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2002,3(2):57-68

A cell culture system for the tick-borne rickettsia Anaplasma marginale offers new opportunities for research on this economically important pathogen of cattle. A. marginale multiplies in membrane-bound inclusions in host cells. Whereas erythrocytes appear to be the only site of infection in cattle, A. marginale undergoes a complex developmental cycle in ticks and transmission occurs via the salivary glands during feeding. We recently developed a cell culture system for A. marginale using a cell line derived from embryos of Ixodes scapularis. Here we review the use of this cell culture system for studying the interaction of A. marginale with tick cells. Several assays were developed using the A. marginale/tick cell system. An adhesion assay was developed for the identification of proteins required by A. marginale for adhesion to tick cells. The effect of antibodies against selected major surface proteins in inhibiting A. marginale infection was tested in an assay that allowed further confirmation of the role of surface proteins in the infection of tick cells. A drug screening assay for A. marginale was developed and provides a method of initial drug selection without the use of cattle. The culture system was used to test for enhancing effects of tick saliva and saliva components on A. marginale infection. The tick cell culture system has proved to be a good model for studying A. marginale-tick interactions. Information gained from these studies may be applicable to other closely related tick-borne pathogens that have been propagated in the same tick cell line.  相似文献   

Evaluation of diallel analysis using β-glucuronidase activity from transgenes in Nicotiana tabacum     

Anthony J. Conner  L.C. Paul Keizer  Ludmila Mlynárová  Willem J. Stiekema  Jan-Peter Nap 《Euphytica》1998,102(2):161-168

A full diallel analysis is a tool for selection in plant breeding that has been subject to many discussions and controversies regarding its interpretation and merits. The analysis of well-defined transgenes by such an approach permits assessment of the value of diallel analyses. The performance of the Eberhart/Gardner diallel approach is analysed for the β-glucuronidase (GUS) activity of six well-defined, homozygous one-locus tobacco (Nicotiana tabacum L.) transgenic lines, each carrying differently located alleles of the GUS gene, and the nulliplex wild type. Tobacco is an inbreeding plant species, therefore all these lines are fully isogenic apart from the T-DNA insertion. The analysis shows that additivity of GUS gene activity as well as epistatic gene silencing translate well in the diallel parameters of general combining ability (GCA) and specific combining ability (SCA) or more detailed versions thereof, when compared to a parsimonious model based on the precise genetic constitution of the transgenic plants lines used as parents. The tobacco line with the highest GUS activity also has the highest GCA, demonstrating that an evaluation of parental phenotype would be sufficient for determining breeding potential. In case of the epistatic gene silencing, however, there is no positive correlation between GCA and parental performance, the reduction in GUS activity is more severe than is to be expected on the basis of parental performance. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

The history of commercial fisheries for European eel commenced only a century ago     

Willem Dekker 《Fisheries Management and Ecology》2019,26(1):6-19

The stock of the European eel is in decline throughout its distribution area—for decades, if not for centuries. Its population dynamics are not well understood. The extremely scattered occurrence, as well as the general lack of quantified information before 1950, prevents a straightforward analysis. This article discusses the history of eel fisheries across Europe, reviewing the literature published before 1940. A follow‐up study is advocated, to unearth primary information in archives across Europe. In the late 1800s, development programmes were initiated in central Europe, complementing the widespread subsistence fisheries with “modern” commercial exploitation of new areas, new markets and new products. In the early 1900s, increasing fisheries and trade were reported throughout northern Europe, and new developments started in the south. This lasted until about 1950—when the current multidecadal decline set in. The eel fisheries have never experienced a period of stable, sustainable exploitation. The decline in the stock is probably not a simple case of overfishing, but a continent‐wide serial depletion of local resources—eventually depleting the whole stock—in times of growing non‐fisheries impacts. Consequences for the European eel protection programme and for the derivation of restoration targets are discussed.  相似文献   

土壤旋切振动减阻的有限元分析   总被引：8，自引：0，他引：8  

蒋建东  高洁  赵颖娣  Willem Hoogmoe  张宪 《农业机械学报》2012,43(1):58-62

提出了一种对旋耕机具施加振动载荷进行压实土壤切削减阻的方法。对板结土壤参数进行土壤三轴测试试验,结合LS—DYNA的MAT147材料模型,测试土壤材料模型参数,并建立了南方丘陵地带板结土壤本构模型及土壤振动旋切过程的有限元数值模型。通过三维数值模拟和计算,分析了外加激励的振型、频率及振幅等因素对土壤切削阻力的影响及变化规律,并得到实现最优减阻效果的各项参数组合。研究结果表明,采用振动旋耕机具进行土壤作业过程中,选择合适振动频率、幅值以及振动类型的外加刀具振动能实现土壤耕作减阻,有效降低机具的土壤切削功率。  相似文献   

Acute amaurotic epilepsy caused by lead poisoning in nonhuman primates   总被引：1，自引：0，他引：1  

B C Zook  R M Sauer  F M Garner 《Journal of the American Veterinary Medical Association》1972,161(6):683-686

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