贵州省主要人造板产品的甲醛释放量研究

[目的]分析人造板产品的甲醛释放量特征及变化,有助于质量监督部门对产品进入市场前的监督、为消费者提供必要的人造板甲醛释放量警戒。[方法]采取厂家样品送检、进厂(场)抽检相结合的办法,对省内人造板产品的甲醛释放量进行监测,持续时间3年。[结果]连续3年的定位抽检和送抽表明,贵州省主要人造板大干燥器法的平均甲醛释放量排序为胶合板>中密板>细木工板>刨花板>饰面板>强化板,相应值为15.934、8.280、6.913、5.717、2.668和0.925 mg/L。甲醛释放量均值较高者变动幅度较小。甲醛释放量频率分布中,强化板、细木工板和刨花板呈"偏左型"偏态分布,胶合板和饰面板呈均匀分布,中密板呈"偏右型"偏态分布。除强化板外,不同人造板甲醛释放量的大、小干燥器测定法之间有着紧密的直线关系,可作为不同方法间的数据转换和预测依据。产地、规格和生产时间对人造板甲醛释放量有影响,均未达显著水平。[结论]不同人造板产品的甲醛释放量存在差异,产地、规格和生产时间对人造板甲醛释放量有影响,均未达显著水平。     

不同复配比例对γ-氨基丁酸茶品质的影响

为弄清不同复配比例菊花改善γ-氨基丁酸茶不良气味的效果,采用感官审评及化学分析方法,研究了不同复配比例对γ-氨基丁酸茶品质的影响.结果表明:感官审评中,各处理的综合品质差异不大,菊花花瓣对外形匀度略有影响;γ-氨基丁酸含量,处理E最高,为1.89 mg/g;处理A最低,仅1.24 mg/g.茶多酚含量,处理B最低,为18.12％,其余处理变化不大,为20.17％～21.36％.游离氨基酸含量,各处理均较高,为5.31％～5.82％.荼多酚、游离氨基酸、可溶性糖含量均达到绿茶或花茶的质量要求,菊花香气消除了γ-氨基丁酸的不良气味.     

Determination of Available Cadmium and Lead in Soil by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

A cloud point extraction (CPE) procedure has been developed for the determination of available cadmium (Cd) and lead (Pb) in soil by flame atomic absorption spectrometry. The proposed method was based on the CPE of a complex from ammonium pyrrolidine dithiocarbamate (APDC) and metal Cd and Pb using emulsifier octyl polyethylene glycol phenol ether (OP) as surfactant. Conditions that would affect the complex formation and separation were researched in detail, including extraction conditions as well as pH, amount of the chelating agent, concentration of the surfactant, equilibration temperature and time, and salt effect. Under the optimized conditions, both of the calibration graphs were linear in range of 0–1.0 μg mL^?1 with detection limits of 0.29 ng mL^?1 for Cd and 2.10 ng mL^?1 for Pb. The relative standard deviation (RSD) for 11 replicate measurements at 0.10 μg mL^?1 of Cd and Pb were 2.18% and 4.04%, respectively. The enhancement factors were 48.8 and 61.6 for Cd and Pb, respectively. The recoveries of Cd and Pb at the spiking level of 0.10 μg g^?1 in soil samples were from 91.7% to 115% and from 91.0% to 115%, respectively. The proposed method has been applied to the determination of available Cd and Pb in soil.     

Determination of Total Nitrogen in Solid Samples by Two-Step Digestion–Ultraviolet Spectrophotometry Method

A two-step digestion–ultraviolet (UV) spectrophotometry method for total nitrogen (N) determination in solid samples is described in this work. Three influencing factors (amount of hydrogen peroxide, amount of sulfuric acid, and digestion time) of the digestion are optimized, and for digestion of a 0.1-g solid sample, the optimal conditions are 0.5 mL of sulfuric acid, 0.2 mL of hydrogen peroxide, and 40 min of the digestion time. The results of ion chromatography show that under the optimal conditions the organic nitrogen almost quantitatively mineralizes into ammonium in the first digestion. The nitrogen content in six real samples has been analyzed under the optimal conditions, and the nitrogen recovery rates of standard compounds added in the real samples were between 88% and 99%. The results obtained by two-step digestion–UV spectrophotometry method are consistent with those by classical Kjeldahl method (correlation coefficient is 0.9999). The possible degradation pathways of three amino acids were also proposed.     

Counting elusive animals: Comparing field and genetic census of the entire mountain gorilla population of Bwindi Impenetrable National Park, Uganda

Accurate population size estimates are an essential part of every effective management plan for conserving endangered species. However, censusing rare and elusive wild animals is challenging and often relies on counting indirect signs, such as nests or feces. Despite widespread use, the accuracy of such estimates has rarely been evaluated. Here we compare an estimate of population size derived solely from field data with that obtained from a combination of field and genetic data for the critically endangered population of mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda. After genotyping DNA from 384 fecal samples at 16 microsatellite loci, the population size estimate was reduced by 10.1% to 302 individuals, compared with 336 gorillas estimated using the traditional nest-count based method alone. We found that both groups and lone silverbacks were double-counted in the field and that individuals constructed multiple nests with an overall rate of 7.8%, resulting in the overestimation of the population size in the absence of genetic data. Since the error associated with the traditional field method exceeded the estimated population growth of 5% in the last 4 years, future genetic censusing will be needed to determine how the population size is changing. This study illustrates that newly improved molecular methods allow fast, efficient and relatively affordable genotyping of several hundred samples, suggesting that genetic censusing can be widely applied to provide accurate and reliable population size estimates for a wide variety of species.     

巴西橡胶树叶片蛋白样品的制备及质谱初步分析

采用TCA-丙酮沉淀法并稍做改进提取巴西橡胶树叶片总蛋白,蛋白溶解后,用试剂盒对蛋白上清液进行纯化和浓度测定。十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和双向凝胶电泳(2-DE)的结果均表明,所制得的蛋白样品质量较高,并且纯化过的蛋白样品2-DE(双向电泳)图谱效果更好(7 cm,考染)。根据预实验结果,选用17 cm IPG预制干胶条对纯化的蛋白样品进行2-DE实验,采用快速银染法进行染色,随机挖取银染胶上6个蛋白点进行MALDI-TOF MS分析和数据库检索,鉴定了3个蛋白,它们是：1-氨基环丙烷-1羧酸合酶2,核酮糖-1,5-二磷酸羧化酶/加氧酶大亚基和F11O4.2。本实验为进一步对巴西橡胶树叶片中具有重要生物学功能蛋白的筛选和鉴定打下了方法学基础。     

投影寻踪模型用于水质等级评价的研究

投影寻踪模型具有可处理高维、非正态数据分类问题的优点,适合于在水质等级评价中应用。该文在介绍该模型基本计算步骤的基础上,经建模分析,得出：各评价等级取值范围内样本个数不小于20即可具有较好的稳定性,投影向量分量的取值范围为[0,1]时更有利于提高计算速度,选用加速遗传算法寻优时间更短,使用图解法或直接比较法更为方便和快捷。这些探索能为该模型在今后的实际应用提供有益参考。     

皖南稻区褐飞虱怀卵雌成虫数量和前期防控对褐飞虱种群动态的影响

通过褐飞虱怀卵雌成虫不同梯度数量下的田间药效试验,研究了安徽省黄山市徽州区单季中稻田二代褐飞虱怀卵雌成虫数量以及前期防控对后期褐飞虱种群动态的影响。试验结果表明:二代怀卵雌成虫数量(x)决定了后期褐飞虱种群大小(y);前期防控(防控:c=1;不防控:c=0)能够明显压低后期褐飞虱种群大小(y);并可建立广义线性回归模型:log(y)=0.943x-3.191c+0.703xc+7.200。根据该模型可以确定两个临界值:(1)x0.4头/百丛时,需要采取"压前控后"策略,即在二、三代低龄若虫高峰期各施药一次,才能有效控制褐飞虱发生危害;(2)x2.4头/百丛时,即使采取"压前控后"的策略,褐飞虱仍然会大发生。2006-2014年大田普查数据亦表明当x2.4头/百丛时,三代褐飞虱极易大发生。本研究明确了褐飞虱前期种群数量对后期发生程度的影响,并可依据前期怀卵雌成虫数量采取不同的防控策略,实现科学防控,减少用药。     

农产品与环境样品中氯虫苯甲酰胺的残留动态分析

氯虫苯甲酰胺是以昆虫鱼尼丁受体为靶标的新型杀虫剂,具有超高的杀虫性能,尤其对鳞翅目害虫具有优异的防效,在水稻、蔬菜、瓜果等农产品生产上大量应用。随着氯虫苯甲酰多年大面积连续使用,其对农产品及环境的安全性日益受到关注。为了解氯虫苯甲酰胺的残留动态规律,笔者总结相关文献,简要概述了氯虫苯甲酰胺在不同样本中的残留分析方法,包括主要的样品提取、净化和检测技术及其优缺点,综述了近年来氯虫苯甲酰胺在蔬菜、水果、粮食作物、土壤等农产品与环境样品中的残留动态,以期为氯虫苯甲酰胺在农业生产上的科学安全使用和残留量的控制提供参考。