Short communication: effects of X-rays on growth and germinal tissue of calves

A study was carried out to measure the growth and germinal tissue responses of young bull calf whose testicles were exposed to different levels of high energy, pulsed beams (X rays). Treatments (absorbed doses) were 0, 1530, 1980, 3060, or 6300 rads. Body weights were measured monthly for 10 mo; testosterone concentrations were measured in mo 2 and 5. At the end of the study, scrotal circumferences were measured, and testes were removed and weighed. Sections of testes were taken, processed, and evaluated for effects on germinal epithelium. Treatments did not affect body weights or weight gains. Testosterone concentrations at mo 5 generally decreased with increased energy dose. Testicular weights were not different among treatments; generally, scrotal circumferences decreased and germinal tissue degeneration increased as the absorbed dose was increased.     

Use of duplex polymerase chain reaction (duplex-PCR) technique to identify bovine and water buffalo milk used in making mozzarella cheese

Molecular biology techniques have been used for species identification in food of animal origin in relatively recent years. A polymerase chain reaction (PCR) based method, the multiplex PCR, was recently applied to species identification in meat and meat products. It allows co-amplification of separate regions of a single gene or specific fragments, each typical of a different animal species in a single PCR reaction, using different pairs of primers in the same reaction mix. In the present paper, the duplex-PCR technique is proposed to identify bovine and water buffalo DNA in a single PCR assay in milk and mozzarella cheese (a typical Italian cheese, originally made from pure water buffalo milk). Because of its lower cost, undeclared bovine milk is added to water buffalo milk for making different kinds of mozzarella cheese. The results of this experiment indicate the applicability of this method, which showed an absolute specificity for the two species and a high sensitivity even down to low DNA concentrations (1 pg). In bovine and water buffalo mixtures of both milk and mozzarella cheese, the minimum concentration tested was 1% of bovine in water buffalo milk and water buffalo in bovine milk. The importance of the somatic cell content in raw milk is also discussed with special reference to the evaluation of mixtures (milk or cheese) of the two species.     

Evaluation and testing of analytical methods for cyanide species in municipal and industrial contaminated waters

Total cyanide analysis by distillation is used most commonly to assess cyanide content of water samples. This manual method is robust but slow and provides no information about cyanide speciation, a significant limitation in that cyanide species have substantially different toxicity characteristics. Seven alternative methods for the analysis of cyanide species or groups of species were evaluated in reagent water and five different contaminated water matrices, including five species-specific methods--weak acid dissociable (WAD) cyanide, free cyanide by microdiffusion, available cyanide, automated WAD cyanide by thin film distillation, metal cyanides by ion chromatography--and two automated techniques for total cyanide--total cyanide bythin film distillation and total cyanide by low-power UV digestion. The species-specific cyanide analytical techniques achieved low, ppb-level detection limits and exhibited satisfactory accuracy and precision for most contaminated waters. Analysis of low concentrations of cyanide species in raw wastewater was problematical for the available cyanide and ion chromatography methods, which experienced significant interference problems and/or low recoveries. There was recovery of significant diffusible cyanide in microdiffusion tests with nickel-cyanide-spiked samples, reflecting dissociation of this weak metal-cyanide complex during the test and demonstrating that the test can recover some fraction of WAD cyanide in addition to free cyanide. The automated total cyanide methods, which involve UV digestion, achieved low detection limits for most waters but exhibited low recoveries for some waters.     

NMR-based metabolomics: a powerful approach for characterizing the effects of environmental stressors on organism health

It is important to assess the chronic effects of chemical, physical, and biological stressors on organisms in the environment. Appropriate methods must enable rapid, inexpensive, and multibiomarker analyses of organism health. Here we investigate withering syndrome in red abalone (Haliotis rufescens), an important wild and farmed shellfish species along the Pacific coast, using a metabolomic approach that combines the metabolic profiling capabilities of nuclear magnetic resonance spectroscopy (NMR) with pattern recognition methods. Foot muscle, digestive gland, and hemolymph samples were collected from healthy, stunted, and diseased abalone, and the extracts were analyzed by NMR. Following spectral preprocessing, principal components analyses of the metabolite profiles were conducted. Our results confirm that NMR-based metabolomics can successfully distinguish the biochemical profiles of the three groups of animals, in every type of tissue or biofluid studied. Furthermore, this discovery-based approach successfully identified novel metabolic biomarker profiles associated with withering syndrome. The application of these methods for investigating other environmental stressors is discussed, as are the advantages of NMR-based metabolomics for biomonitoring, particularly in conjunction with gene and protein expression profiling.     

小水电给尼泊尔边区带来的社会效益

尼泊尔的小水电开发潜能巨大，这是给偏远地区村庄提供电能以及促进工程周边地区社会经济整体发展的一个有效途径。本文针对尼泊尔私营企业在该领域所作的努力的一个实例，对该问题进行了分析研究。     

Criteria to determine food allergen priority

The emergent health issue of food allergens presents an important challenge to the food industry. More than 170 foods have been reported in the scientific literature as causing allergic reactions. Clearly, it would be impossible to deal with the presence of trace amounts of all these in the context of food labeling. If the decision to classify major allergens is based solely on the knowledge and experience of allergists and food scientists in the field, without scientifically defined criteria, it is likely to lead to a proliferation of lists. Such practices may lead to an unnecessary elimination of foods containing important nutrients. This paper defines food allergy, food intolerance, and food anaphylaxis and identifies criteria for classifying food allergens associated with frequent allergic reactions. A practical list of food allergens that may result in potentially life-threatening allergic reactions is provided. A mechanism-based (i.e., immunoglobulin E mediated), acute life-threatening anaphylaxis that is standardized and measurable and reflects the severity of health risk is proposed as the principal inclusion criterion for food allergen labeling. Where available, prevalence in the population and threshold levels of allergens should be used as an additional guide to identify possible future labeling needs.     

Microwave radiometer blackbody calibration standard for use at millimeter wavelengths

We describe a high-temperature reference load designed for calibration of microwave radiometers at frequencies of 80-150 GHz. An effective temperature of 410 K and a power reflection coefficient of less than 5 x 10(-4) have been measured at frequencies between 85 and 95 GHz.     

马蒂尔坝址区的滑坡及其加固措施

拟建在摩洛哥经部的马蒂尔坝水库，其地质测量清楚地表明有一些大滑坡存在，特别是在未来水库的库尾和１９６１年投入运行的昂那克拉大坝下游处，这些滑坡对现有的建筑物的基础结构和规划中的大坝会产和不利的影响，工程业主通过地球物理法和岩心探法，以及设置斜仪和测量水准点对此进行了专门研究。根据这些研究成果考虑采用适用于坝址条件的加固方法。     

加强尚扎流域的水资源管理

西班牙西南部78m高的安德瓦洛堆石坝的投入运行对加强尚扎流域水资源的管理和利用将起到重要的作用。大坝将有助于满足旅游业和农业繁荣兴旺的区域内快速增长的供水需求。未来计划修建一座电厂。     

Simulation of packed-bed chromatography utilizing high-resolution flow fields: comparison with models

A computer simulation of a section of the interior region of a liquid chromatographic column is performed. The detailed fluid flow profile is provided from a microscopic calculation of low Reynolds number flow through a random packed bed of nonporous spherical particles. The fluid mechanical calculations are performed on a parallel processor computer utilizing the lattice Boltzmann technique. Convection, diffusion, and retention in this flow field are calculated using a stochastic-based algorithm. This computational scheme provides for the ability to reproduce the essential dynamics of the chromatographic process from the fundamental considerations of particle geometry, particle size, flow velocity, solute diffusion coefficient, and solute retention parameters when retention is utilized. The simulation data are fit to semiempirical models. The best agreement is found for the "coupling" model of Giddings and the four-parameter Knox model. These models are verified over a wide range of particle sizes and flow velocities at both low and high velocity. The simulations appear to capture the essential dynamics of the chromatographic flow process for non-dimensional flow velocities (Péclet number) less than 500. Since the same packing geometry is utilized for different particle size studies, the interpretation of the parameter estimates from these models can be extended to the physical column model. The simulations reported here agree very well with a number of experiments reported previously.