Minimum propagation diameter and thickness of high explosives

The critical diameter and critical thickness of two heterogeneous explosives were measured experimentally. By comparing these experimentally determined values of critical diameter and critical thickness, the role of front curvature in the failure of the detonation can be investigated. Current theories of detonation based on front curvature would predict the critical diameter should be twice the critical thickness. Experimentally, the expected two-to-one ratio was only validated for the case of a heterogeneous explosive with very fine scale heterogeneities. The ratios of critical diameter to critical thickness (for the two selected explosives) are also compared to previously measured values for homogeneous (liquid) explosives in order to contrast the dominant failure mechanism in these different explosives.     

Mass media and environmental knowledge of secondary school students in Hong Kong

A postal survey on a random cluster sample of 1032 secondary school students in Hong Kong was conducted to investigate what and how much students know about the environment and how their knowledge is related to use of mass media. Results indicated that students were very knowledgeable on general and local environmental issues. The average score for environmental knowledge was 60.7 on a 100-point scale. There was some indications that students' environmental knowledge was shaped and limited by the reporting of environmental news in Hong Kong. Television news viewership had positive correlation with students' environmental knowledge while Chinese newspaper readership had a positive but weak correlation. Male students and students in higher forms were more knowledgeable about the environment. The study established a comprehensive measure for both general and local environmental knowledge with an acceptable level of internal consistency for subsequent studies.     

Prenatal sonographic detection of intra-abdominal extralobar pulmonary sequestration: Report of three cases and literature review

Three cases of intra-abdominal extralobar pulmonary sequestration detected antenatally by ultrasound are reported. One case was associated with a large left diaphragmatic hernia. Sonographically, all the cases were found in the left supra-renal region presenting as a well-defined echogenic mass with cystic hypoechoic areas. The condition should be considered in the differential diagnosis of all antenatally detected upper abdominal echogenic masses, particularly when associated with a diaphragmatic hernia. Postnatal ultrasound-guided fine needle aspiration biopsy in one case yielded respiratory type epithelium and this procedure could provide a reasonably confident diagnosis of the lesion.     

城市污水快速渗滤处理技术与常用污水处理技术的对比分析

快速渗滤技术与传统氧化塘技术比较，单位处理负荷大幅度提高，占地面积明显减少；与传统污水处理厂比较，设计施工简便、建设费用低、运行费用小，管理方便。     

陕西省冬春季PM2.5时空分布特征研究

根据陕西省2016年12月至2017年5月PM_2.5质量浓度逐小时数据，利用ArcGIS分析陕西省PM_2.5污染时空变化格局，并分析造成南北差异的原因，再利用小波分析手段探讨各市PM_2.5污染时间序列周期和突变特性。结果表明：（1）陕西省冬季PM_2.5污染重，春季污染轻，并表现出"关中高，南北低"的特征，秦岭南北经济发展差异和供暖差异是控制陕西省PM_2.5污染空间格局的主要原因；（2）冬季和春季单日PM_2.5浓度变化趋势基本一致，为"双峰双谷型"，日最低值出现在16∶00~18∶00；（3）Morlet小波分析结果显示，陕西省PM_2.5日均变化序列存在多时间尺度特征。陕北城市PM_2.5污染第1主周期为40 d，关中城市和陕南商洛市有40 d和65 d两个共同周期，安康市和汉中市共同周期为20 d和80 d；（4）陕西省PM_2.5突变事件冬季频繁而春季较少，多发生在1月和2月，春季1次大范围的沙尘天气，造成了陕西省5月5日8个城市PM_2.5污染浓度剧增。     

False non-paternity in a family for prenatal diagnosis of β-thalassaemia

Initial screening for the common β-thalassaemia mutations with allele-specific oligonucleo-tide probes in an at-risk family suggested non-paternity. Subsequent DNA fingerprinting of the members proved otherwise. The mother had a codon 41/42 frameshift mutation and the father's defect, determined by direct sequencing of PCR-amplified β gene, was a codon 43 nonsense mutation. In the affected children, the close proximity of these two defects resulted in the absence of a hybridization signal to the normal probe in that region and a wrong assumption of homozygosity for the codon 41/42 mutation. The non-reactivity of the father's amplified DNA to the codon 41/42 thalassaemic probe accounted for the initial wrong conclusion of non-paternity. Since prior screening for β-thalassaemia mutations is done in all prenatal diagnosis programmes and concomitant inheritance of these two defects is relatively common in the Chinese, this ‘artefact’ of false non-paternity is worth noting.     

Growth and value of Chlorella salina grown on highly saline sewage effluent

Chlorella salina was successfully cultivated in secondarily treated domestic sewage effluent of salinity (14%) in an outdoor cultivation tank. Removal efficiencies of NH₄⁺ -N, NO₃⁻ -N, and PO₄³⁻ -P by this alga from secondarily treated sewage effluent were 89–100%, 35–66% and 100%, respectively. The high removal efficiencies of inorganic N and P means that this process can be used as a tertiary sewage treatment. The yield of the sewage-grown algae was 5.1 g m⁻² day⁻¹ for a retention time of 6 days. The high protein content (46.8%), relatively good amino-acid profile and low metal content enabled the use of algal biomass as feed supplement for the silver carp (Hypophthalmichthys molitrix). The food conversion ratios (FCR) of 5% and 10% sewage-grown algae supplemented fish food were better than on the control diet (i.e. artificial fish food alone), while the FCR of 20% sewage-grown algae supplemented fish food and live sewage-grown algae alone were inferior to that on the control diet. These results indicate that cultivation of C. salina in secondarily treated sewage effluent of high salinity can be used as a tertiary sewage treatment to remove inorganic N and P from secondarily treated sewage effluent to reduce pollution problems, and to produce algal protein suitable as a supplement for fish feed in aquaculture.     

王莉丽与她的《绿媒体》

“环保传播”是王莉丽喜爱的词汇。在她看来，这个区别于“环境宣传”的命名，代表着环境文化的反思与建构。这就有了《绿媒体》，有了她的关于“环保传播”，以及由此衍生出来的话题，有了本刊对其绿色理想的关注。[编者按]     

重庆大气酸沉降与钢材腐蚀

通过在重庆城区、郊区的钢材大气曝露试验得到了不同品种钢材的大气腐蚀率．结果表明：以燃煤硫污染为主要特征的干湿酸沉降加速了钢材腐蚀。