Log Characteristics and Sawn Timber Recovery of Home-Garden Teak from Wet and Dry Localities of Kerala, India

There is a widely held view among smallholders that teak timber produced from small-scale agroforestry systems, especially home-garden forestry, fetches a lower price than that from conventional plantation forestry. To examine the veracity of this view, the wood quality attributes of teak from two home gardens in the district of Ernakulam (wet site) and Palakkad (dry site) in India were compared to those of forest plantation in Nilambur. The logs were graded using standard timber trade practices into high, medium and low quality as determined by the potential sawn timber grade-yield recovery pattern. Of 96 home garden teak logs (aged 35 years) from wet and dry sites, 59% belonged to timber Grade II–IV and the rest were classified as poles. Grade I logs (export quality) with a girth above 150 cm were not available from either of the homesteads. Faster-grown teak in the wet site produced large diameter logs (dbh 1.37 m) with average diameter of 39.6 cm, which is comparable to that of best site quality in India. In contrast, the average dbh for teak grown in the dry site was 24 cm as compared to the average dbh of 31 cm recorded from the same aged forest plantation in Nilambur. It was found that only 10% of logs belonged to Grade II timber and the rest fell under grades III and IV with more frequent visual defects. The sawn timber recovery percentage was lower for the dry site (66.8%), whereas there was no significant difference in grade from the wet and forest plantation sites, with recovery rates of 76.5% and 78.8%, respectively. The general notion that home garden teak has a large proportion of sapwood seems to be baseless, no significant difference being found between the heartwood-sapwood ratio of home-garden and forest plantation teak. Lack of appropriate silvicultural practices in home-garden forestry caused the production of more defective logs, adversely affecting the market price of timber.

三聚氰胺的毒性残留及检测方法研究进展

三聚氰胺是一种化工原料,但由于其含氮（N）量高,常被不法商人添加到食品及饲料中,对人类及动物健康造成了严重危害。三聚氰胺的急性毒性很低,口服的半数致死量（LD50）为3100～3300mg·kg^-1;慢性毒性试验动物症状主要表现为肾结石及膀胱癌。三聚氰胺在生物体内无代谢转化,以原体形式或同系物形式排出体外。文章对三聚氰胺的毒性、残留代谢及检测方法进行了综述。     

重型木结构在我国的应用和发展

文中总结了重型木结构的特性与相关技术发展动态以及在发达国家和地区的工程应用现状, 结合我国经济社会发展现阶段面临的环境问题和国内土木工程建设技术发展要求, 从政策导向、社会需求、木材资源和技术力量等方面对重型木结构在我国的应用适宜性进行了分析, 最后指出其应用前景。     

南昌市市售蔬菜有机磷农药残留调查及其原因分析

对南昌市市售蔬菜有机磷农药残留超标情况进行了系统调查,发现 21. 1%的样品中有机磷农药残留超标。分析了导致蔬菜有机磷农药残留超标的原因。     

转基因香石竹Moonlite品系特异性定性PCR检测方法的建立

以转基因香石竹品种Moonlite(月之伊人)为研究对象,通过TAIL-PCR方法,获得外源基因插入位点的左侧旁邻序列。根据旁邻序列设计引物,建立品系特异性定性PCR方法,其扩增片段覆盖了转化载体及香石竹基因组临界序列。本方法特异性好、灵敏度高,可快速、准确、高效地检测转基因香石竹Moonlite品种。     

猪伪狂犬病病毒gE抗体胶体金免疫层析检测方法的建立及应用

以纯化的抗人红细胞单链抗体(ScFv)-猪伪狂犬病病毒(PRV)gE蛋白双功能融合蛋白为诊断抗原和胶体金标记物,以羊抗猪IgG包被硝酸纤维膜作为质控带,制作检测猪伪狂犬病毒gE抗体的双抗原胶体金试纸条。利用方阵滴定试验筛选出金标抗原最佳工作浓度为17.6μg,检测线诊断抗原最佳标记量为1.76μg,血清最佳稀释度为1∶10,作用时间15 min,与猪瘟病毒(CSFV)、猪细小病毒(PPV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪乙型脑炎病毒(JEV)、猪布鲁菌(Brucella)阳性血清和PRVgE缺失疫苗接种的猪免疫血清检测线均不出现红色条带,与PRV标准阳性血清反应检测线出现红色条带。试纸条操作简单,肉眼于15 min内可判定结果;试纸条在室温保存6个月,其特异性和敏感性没有明显变化;与美国IDEXX和法国LSI gE-ELISA抗体检测诊断试剂盒检测结果比较,1 164份猪血清的符合率均为90.55%。制备的胶体金试纸条具有操作简便、敏感性和特异性较高的特点,可用于PRV野毒感染的快速筛查。     

商品肉鸡舍内环境因子含量测定及分布规律研究

 对商品肉鸡舍内主要环境因子如氧气、二氧化碳、氨气、硫化氢浓度、细菌浓度以及温度、湿度等进行定量检测,并分析各环境因子变化规律。试验结果显示,该鸡舍内氧气浓度平均为19.6%,比舍外降低6.0%;二氧化碳浓度平均为3 673×10⁶ mg/m³,为舍外二氧化碳浓度的8.48倍;细菌浓度平均为6.9×10⁵ cfu/m³;舍内平均温度为24.0 ℃,相对湿度为75.5%;氨气浓度在试验期间均超过100 mg/m³;硫化氢浓度低于检测仪器最低浓度1 mg/m³。试验表明,鸡舍内空气环境中二氧化碳浓度与氨气浓度严重超标,氧气含量不足,各环境因子与病原微生物相互作用,可能是导致鸡群发病的主要原因。     

机器视觉在农产品物流分级检测中的应用

综述了近些年国内外机器视觉技术在农产品品质分级检测中的研究进展,选取水果、谷物籽粒、家畜、家禽和蔬菜为代表,重点阐述了机器视觉技术针对这些农产品特征进行分级检测的方法以及成果。同时,总结了目前机器视觉技术应用于农产品物流分级检测的不足之处,展望了未来的发展趋势。     

猪瘟病毒结构蛋白抗体间接ELISA检测方法的建立及评价

通过研究猪瘟(CSF)疫苗免疫猪抗结构蛋白E2、E0和C抗体的产生规律,为临床制定合理的CSF疫苗免疫程序提供参考。利用间接ELISA方法检测CSF疫苗免疫猪过程中,抗E2抗原血清抗体的产生特征;分别以重组猪瘟病毒(CSFV)结构蛋白E0和C为抗原,建立检测血清抗体的间接ELISA方法,评价其敏感性和特异性,并检测疫苗免疫过程中抗E0和C蛋白抗体的消长规律。结果显示:CSFV-E0和CSFV-C间接ELISA抗体检测方法的抗原最佳包被质量浓度分别为2.09和1.59μg/mL,待检血清样本最适稀释度分别为1∶60和1∶80,酶标二抗稀释度分别为1∶100和1∶350,2种ELISA方法与常见猪病原的阳性血清无交叉反应,具有良好的特异性。CSF疫苗免疫后第7天即可检测到抗E2、E0和C蛋白的抗体,其中抗E2和E0的抗体在免疫后第21天达到最高水平,E2抗体滴度先上升后下降,E0抗体在免疫后第21天开始下降并最终趋于稳定;C蛋白抗体在免疫后第7天出现,随后开始下降,在第28天转为阴性。结果表明,利用重组抗原建立的CSFV血清抗体ELISA检测方法,可以用于评价CSF疫苗免疫后血清中针对3种结构蛋白的抗体消长特点,从而为临床猪瘟疫苗免疫程序的制定提供参考。     

Advances on Detection Methods for Residues of Nitrofurans in Food

Nitrofurans are broad-spectrum antibiotics which have been widely used in food animals to the prevention and treatment of gastrointestinal infections.Due to abuse of drugs by criminals,animals could produce drug-resistant strains,which reduces the role of antibiotics.Meanwhile,excessive drugs residues in food has carcinogenic,teratogenic and mutagenic effects to the human body.In this paper,the damage and the detection methods of the residues of the nitrofurans in food are surveyed.The main detection methods include high performance liquid chromatography,liquid chromatography-mass spectrometry,liquid chromatography tandem mass spectrometry,enzyme-linked immunoassay,colloidal gold immunoassay and fluorescence immunity analysis method.The research status of various detection methods are summarized and the suggestions for further research are put forward.It is expected to provide reference for future research.