Radionuclide levels at two sites in a water extraction area in the Netherlands after chernobyl

The coastal dune aquifer, providing drinking water for a large part of the population of the western Netherlands, is recharged by fainfall and artificial infiltration of Rhine water. Chernobyl fall-out has been detected in both water sources. At the Castricum lysimeter station the rainfall-derived water, draining from 2.25 m of unsaturated sandy soil, shows levels of Cs-137 around the detection limit of 20 to 40 mBq kg^?1. At this site, the soil itself retained some Chernobyl-derived Cs-137 in the top 10 cm, where a similar quantity of old Cs-137 has also been retained. Penetration of old Cs-137 is deeper (up to 70 cm) under oak vegetation than in the bare soil. In the infiltration channels, fed by Rhine water, the bottom mud contains only Chernobyl-derived Cs nuclides. Radioactivity from Cs-137 is about one tenth of that from natural radioactivity due to K-40. Cesium levels are apparently unrelated to adsorptive properties.     

Derivation, safety and efficacy of a Marek's disease vaccine developed from an Australian isolate of very virulent Marek's disease virus

Objective To develop a serotype 1 Marek's disease (MD) vaccine from a very virulent MDV (vvMDV) pathotype and demonstrate safety and efficacy against early challenge with very virulent field strains in the presence of maternal antibody.
Study design Strain BH 16 was isolated and attenuated by serial cell culture passage. One of two cloned passages was selected for vaccine development following early laboratory-scale protection trials in commercial birds. Comparative protection trials were carried out on the BH 16 vaccine and on a CVI 988 Rispens vaccine using commercial and SPF chickens. Challenge viruses used were either a low passage strain BH 16 virus, the Woodlands No. 1 strain or MPF 57 strain of MDV. The BH 16 vaccine was back-passaged in SPF chickens six times and virus recovered from the final passage and the original vaccine virus were tested for safety. The immunosuppressive potential of the BH 16 and Rispens vaccines was also assessed in parallel.
Results The BH 16 and Rispens vaccines induced comparable levels of protection when used as monovalent or multi-valent vaccines, although protection achieved with the mono-valent vaccines was lower. No gross tumour formation was evident in any birds receiving the BH 16 vaccine or bird-passaged virus, although microscopic lesions were present in 2/12 birds that received the bird-passaged virus. In tests for immunosuppression, there was no histological evidence of damage to either the bursa of Fabricius or the thymus.
Conclusion The BH 16 vaccine was shown to be safe and at least as protective as the Rispens vaccine against three highly virulent MD challenge viruses.     

干草原区植被保护支持技术研究绿色添加剂—大蒜(Allium sativum)对肉牛增重影响的研究

大蒜是一种植物鳞茎 ,作为肉牛饲料添加剂尚未见报道。本文研究的目的是 :研究大蒜对肉牛增重的影响。试验选用西门塔尔杂交后代公牛 3 8头其中 3 5头牛随机分为七组 ,大蒜组 A( 50 g/ d.头 )、D( 1 0 0 g/ d.头 )、F( 1 50 g/ d.头 ) ;大蒜素组 C( 0 .2 g/ d.头 )、E( 0 .4g/ d.头 )、G( 0 .6g/ d.头 ) ;对照组。试验采用完全拉丁方设计。试验结果表明 :1 .大蒜在添加 74.6g/ d.头左右 ,对肉牛增重有明显的促进作用 ,Y=-0 .0 0 2 2 x2 +0 .3 2 8x+2 8.3 2 ,R2 =0 .972 8( Y为增重 ,X大蒜用量 )。 2 .当大蒜素添加量为 0 .3 5g/ d.头时肉牛体增重最高 ,y=-92 .5x2 +65.4x+2 7.3 3 R2 =0 .91 96( Y为增重 ,X大蒜素用量 )。 3 .大蒜促进肉牛增重的主要成分是大蒜素     

欧拉羊与山谷型藏羊杂交F_1代羔羊补饲兼放牧育肥试验效果观察

用欧拉羊杂交改良山谷型藏羊,对杂交F1代羔羊补饲兼放牧育肥试验,补饲阶段试验结果表明：经过90 d补饲,试验组增重10.88kg,比对照组高4.32 kg（P〈0.01）,平均日增重0.121 kg,比对照组高0.048 kg;放牧育肥阶段试验结果表明：经过3个月放牧育肥,试验组增重9.09 kg,比对照组高2.67 kg（P〈0.05）,平均日增重0.101 kg,比对照组高0.03 kg。     

Sex Pheromones of Summer Fruit Tortrix Moth Adoxophyes orana: Two Synergistic Isomers

Both cis-9-and cis-11-tetradecenyl acetate were isolated from 2500 virgin females of the summer fruit tortrix moth Adoxophyes orana (F.v.R.) by gel permeation, column chromatography on silica gel, and gas chromatography. Their chemical, physical, and biological properties were identical to those of the synthetic compounds. In contrast to the single compounds, mixtures of these pheromones were highly active in laboratory and field tests. Catches, in traps, with the pheromone mixture were comparable to those obtained when live females were used as bait. This is the first example of a member of the lepidoptera in which the presence of two isomers is an absolute requirement for activity in laboratory and in field experiments.     

Polystyrene-dendrimer amphiphilic block copolymers with a generation-dependent aggregation

A class of amphiphilic macromolecules has been synthesized by combining well-defined polystyrene (PS) with poly(propylene imine) dendrimers. Five different generations, from PS-dendr-NH(2) up to PS-dendr-(NH(2))(32), were prepared in yields of 70 to 90 percent. Dynamic light scattering, conductivity measurements, and transmission electron microscopy show that in aqueous phases, PS-dendr-(NH(2))(32) forms spherical micelles, PS-dendr-(NH(2))(16) forms micellar rods, and PS-dendr-(NH(2))(8) forms vesicular structures. The lower generations of this class of macromolecules show inverted micellar behavior. The observed effect of amphiphile geometry on aggregation behavior is in qualitative agreement with the theory of Israelachvili et al. The amphiphiles presented here are similar in shape but different in size as compared with traditional surfactants, whereas they are similar in size but different in shape as compared with traditional block copolymers.     

Titanium carbide nanocrystals in circumstellar environments

Meteorites contain micrometer-sized graphite grains with embedded titanium carbide grains. Although isotopic analysis identifies asymptotic giant branch stars as the birth sites of these grains, there is no direct observational identification of these grains in astronomical sources. We report that infrared wavelength spectra of gas-phase titanium carbide nanocrystals derived in the laboratory show a prominent feature at a wavelength of 20.1 micrometers, which compares well to a similar feature in observed spectra of postasymptotic giant branch stars. It is concluded that titanium carbide forms during a short (approximately 100 years) phase of catastrophic mass loss (>0.001 solar masses per year) in dying, low-mass stars.     

欧拉羊与山谷型藏羊杂交后代各年龄段生长速度分析

对欧拉羊与山谷型藏羊杂交试验组和山谷型藏羊本交对照组所产的后代进行了初生、3月龄、6月龄、12月龄、18月龄的体重跟踪测定和差异显著性检验。结果表明,欧山杂交F1代公、母羊初生～3月龄,3～6月龄,6～12月龄、12～18月龄日增重分别比同期对照组后代日增重均快,差异极显著(P﹤0.01),并且随着月龄的增加,日增重降低。说明欧山杂交后代的生长速度在初生至12月龄增长速度快,而12～18月龄的增长速度减慢,适宜羔羊肉生产。