APDC和氧化铝富集-冷原子吸收光谱法测定水产品中的痕量汞

用吡咯烷二硫代氨基甲酸铵（APDC）作配位剂,在pH=5.0～6.0的条件下,用氧化铝捕集、膜滤纸抽滤分离Hg-APDC配合物,然后用0.1moL/L盐酸从膜滤纸上洗下氧化铝,得到能够直接用冷原子吸收光谱法测定汞的悬浊液。该法特征质量为2.1×10-11g/1%。在最佳条件下,用这个方法测定了5种水产品中的痕量汞,当测定次数n=6时,标准偏差SD为0.0314～0.136,相对标准偏差RSD为1.67%～2.87%,样品的加标回收率在94.2%～101%之间,结果较为满意。      

Correlation of cooking time with water absorption and changes in relative density during boiling of cassava roots

Consumers prefer cassava roots that cook quickly during boiling. Current methods to evaluate cooking time (CT) are slow and labour-intensive. This article describes improved protocols for assessing CT in roots. We evaluated CT in 36 genotypes monthly at 8–11 months after planting. CT showed differences for plant age at harvest and among genotypes. During boiling, roots absorbed water (WAB) and thus reduced their relative density (DEN). We classified three groups of genotypes with increasing CT (≤25 min, 25–40 min and >40 min), associated with decreasing WAB, respectively, 15.3 ± 3.1, 10.7 ± 1.7 and 4.9 ± 3.8% of initial root weight. A similar trend was observed for changes in DEN (46.3 ± 9.8, 54.5 ± 11.1 and 75.9 ± 6.9% of initial DEN, respectively). The highest correlations between WAB and DEN with CT (r² > 0.6) were found at 30-min boiling. These alternative protocols facilitate screening large numbers of cassava genotypes for CT.     

Prediction of water absorption and swelling of thermally modified fir wood by artificial neural network models

European Journal of Wood and Wood Products - Classification is a useful tool for analyzing the quality control of thermally modified timber. This study aimed to predict water absorption and...     

Comparative 3D simulation on water absorption and hygroscopic swelling in japonica rice grains under various isothermal soaking conditions

Cracking in rice grains caused by moisture absorption is a major concern among food processors because it has a detrimental effect on the texture. This paper aimed to simulate moisture diffusion three dimensionally (3D) using Fick's diffusion equation, compare the results with an empirical model (Peleg's equation), and simulate in 3D the hygroscopic swelling in rice during soaking at 25, 35, 45 and 55 °C. This study intends to provide preparatory information in understanding the cracking mechanism during soaking. The concept was based on finite element analysis to evaluate both the moisture diffusion and hygroscopic expansion coefficients of milled rice using the reconstructed 3D model of rice geometry. The proposed model was satisfactory for describing the moisture absorption kinetics with root mean square error (RMSE), that ranged from 0.66 to 2.52% dry basis. The results of the 3D simulation of hygroscopic swelling were found to be adequate in representing the swelling characteristics of rice. Analysis of 3D simulation enabled both quantitative and qualitative assessment of the changes in the amount, distribution of moisture, and expansion in the geometry of rice grains.     

顶空-气相色谱法测定5种挥发性消毒副产物在饮用水加热前后的含量变化

目的建立顶空气相色谱法测定生活饮用水在加热前后5种挥发性消毒副产物三氯甲烷、四氯化碳、一溴二氯甲烷、二溴一氯甲烷、三溴甲烷含量的变化。方法取出厂水、末梢水、煮沸的开水、敞口持续煮沸1 min的开水各10 mL于顶空瓶中70℃顶空平衡15 min,取上层气体进样进行气相色谱分析, HP-5毛细管色谱柱分离,电子捕获检测器检测,外标法定量。结果 5种挥发性消毒副产物在不同的浓度下线性关系良好,相关系数为0.9992～0.9996;加标回收率为83.3%～101.8%。其中三氯甲烷在4种样品中检出浓度为0.717～44.9μg/L;四氯化碳、一溴二氯甲烷、二溴一氯甲烷均有不同程度检出,三溴甲烷均未检出。结论经过氯化消毒的自来水煮沸后,挥发性消毒副产物含量大幅降低,其中以开盖持续煮沸1min的开水中含量最低,因此建议饮用自来水需要提前煮沸。     

预富集-冷原子吸收光谱法测定水中的痕量汞

建立了一种预富集-冷原子吸收光谱法测定水中的痕量汞的方法,研究了预富集条件、测定条件等对灵敏度的影响.在最佳的条件下,用这个方法测定水样中的痕量汞,150ml样品中,特征质量为0.01ng/1%,标准偏差为0.0008～0.001,回收率为95.0%～100.0%,结果较为满意.     

Effect of oligonol intake on cortisol and cytokines,and body temperature after leg immersion into hot water

This study investigated the effects of oligonol intake on cortisol, interleukin (IL)-1β, and IL-6 concentrations in the serum as well as body temperature after leg immersion into hot water. Thirteen healthy male volunteers participated in this study. Each subject received oligonol (100 mg) before leg immersion into hot water. Skin and tympanic temperatures were measured and mean body temperatures were calculated. Serum concentrations of cortisol, IL-1β, and IL-6 were measured during and after leg immersion. Individuals who received oligonol had significantly decreased cortisol concentrations and serum levels of IL-1β and IL-6 compared to ones who did not receive oligonol. In addition, skin, tympanic, and mean body temperatures of oligonol group were maintained at lower degree overall recovery period compared with placebo group. These results suggest that oral oligonol intake before hot water immersion had a significant effect on inhibition of pyrogenic cytokine response and thermal suppression in healthy young men.     

Determination of total mercury in seafood by cold vapor-atomic absorption spectroscopy (CVAAS) after microwave decomposition

A method was developed for determination of total Hg in seafood using 10% w/v SnCl₂ · 2H₂O and continuous flow CVAAS after microwave decomposition in closed vessels. Seafoods were decomposed with 5 mL HNO₃ and 1 mL 1% w/v NaCl at 200 °C, transferred to polypropylene tubes containing 3.5 mL HCl, and diluted to 50 mL with H₂O. Standards were prepared in diluent containing 10% v/v HNO₃, 7% v/v HCl, and 0.02% w/v NaCl. Potential interference by 22 elements was evaluated. Interference by Se and Au was observed. Stability of standard solutions in HNO₃, HCl and NaCl was evaluated. Stabilizing effect of chloride was demonstrated. Results for six reference materials containing 0.0371–1.59 mg/kg Hg were 86–106% of certificate values. Concentrations in 11 varieties of seafood were 0.015–1.78 mg/kg. Average recoveries of inorganic and organic Hg added to seafood were 102% and 99%, respectively; average recoveries from fortified method blanks were 100% and 97%, respectively. The limits of quantitation were 0.0022 and 0.011 mg/kg in seafoods and reference materials, respectively.     

超声波辅助香菇多糖的水浸提取工艺条件研究

利用超声波辅助热水浸提法提取香菇中的多糖,采用正交试验方法优化了工艺条件,结果表明,采用正交试验优化影响香菇多糖得率的主次因素顺序为温度＞料液比＞时间.最佳的提取工艺参数为:浸提温度70℃,浸提时间120min,料液比1∶60 (g∶mL).在此条件下香菇多糖得率可达3.37％.     

活性印染逐格逆流全沸洗工艺

活性染料的水洗主要分为两个阶段,一是去除纤维表面浮色、盐和碱的脏洗阶段,第二是去除纤维内部浮色,以提供较好色牢度。分析了影响水洗效果的主要因素,包括染料的性质、电解质浓度、水洗温度、洗液pH值、织物带液量、水质和皂洗剂等。在传统水洗的基础上提出了全新的全沸洗工艺。实践证明,活性染料平幅全沸洗工艺可节水40%～50%,节约蒸汽20%～30%。     

还需挂上火车头——有所悟才能有所为(续篇)

一、逻辑推理1.既然讨论的中心是：知识经济对印刷业的挑战,那么,与知识经济关系最密切的出版印刷也就应该是讨论的重点和主题。2.“出版印刷”不仅仅是印刷业的事,主要还涉及新闻、书刊、杂志及科教等出版单位,印刷仅是受前者的委托而进行加工服务。故如何适应21世纪知识经济的挑战,制订规划或对策若仅有印刷界而没有出版界的积极参与,就难免落空或至少事倍功半。3.据此,要适应21世纪知识经济对印刷业的挑战,重点应抓好“出版印刷”的对策,而“出版印刷”就必须把“出版”与“印刷”两个界面紧贴在一起,由出版界与印刷界共同来拟…     

Microbiological effectiveness and cost of boiling to disinfect drinking water in rural Vietnam

Despite certain shortcomings, boiling is still the most common means of treating water in the home and the benchmark against which alternative household-based disinfection and filtration methods must be measured. We assessed the microbiological effectiveness and cost of boiling among a vulnerable population relying on unimproved water sources and commonly practicing boiling as a means of disinfecting water. In a 12 week study among 50 households from a rural community in Vietnam, boiling was associated with a 97% reduction in geometric mean thermotolerant coliforms (TTCs) (p < 0.001). Despite high levels of faecal contamination in source water, 37% of stored water samples from self-reported boilers met the WHO standard for safe drinking water (0 TTC/100 mL), and 38.3% fell within the low risk category (1--10 TTC/100 mL). Nevertheless, 60.5% of stored drinking water samples were positive for TTC, with 22.2% falling into the medium risk category (11--100 TTC/100 mL). The estimated cost of wood used to boil water was US$ 0.272 per month for wood collectors and US$ 1.68 per month for wood purchasers, representing approximately 0.48% to 1.04%, respectively, of the average monthly income of participating households.     

预富集-氢化物发生原子吸收光谱法测定水产品中的痕量硒

研究了预富集-氢化物发生原子吸收光谱法测定水产品中的痕量硒的新方法。用吡咯烷二硫代氨基甲酸铵(APDC)作配位剂,在pH4.0～6.5的条件下,用固体硅胶捕集、膜滤纸抽滤分离Se-APDC配合物,然后用0.1moL/L盐酸从膜滤纸上洗下硅胶,得到能够直接用氢化物原子吸收光谱法测定的硒悬浊液。该法操作简便,富集速度快。100mL溶液,特征质量为1.5×10-11g/1%。在最佳条件下,用这个方法测定了水产品中的痕量硒,当n=6时,标准偏差为0.0027～0.0054,变异系数为0.012～0.028,样品的加标回收率在95.2%～104.6%之间,结果较为满意。     

水煮法对亚麻籽脱毒的工艺研究

在浸提试验的基础上,根据各工艺参数和生氰糖苷去除量之间的关系,确定了水煮法的最佳温度为80℃、最合适的溶剂倍量为10和浸提时间120 min.     

有所悟 才能有所为——参加第七届世界印刷大会与第五届北京国际印刷技术展览会归来

第七届世界印刷大会与第五届北京国际印刷技术展览会在以李岚清为首的各级有关领导的关怀与支持下，通过国内外有关人士的精心组织与安排，赢得业内外广泛的重视与参与，终于在胜利的喜悦中落下帷幕。这将在中国印刷史上添上重彩浓墨、值得纪念的一页。作为参与者之一，《印刷杂志》等专业期刊敦促我发表些个人感受与体会，既感盛情难却，又属义不容辞，真诚地在此以抛砖引玉的愿望，略抒己见。一、认清时代背景和特点才能充分体会本届大会的时代意义世界印刷大会是国际印刷业规模最大、影响最广的行业盛会。第七届大会适逢新世纪伊始，选择…     

Assessing the microbiological performance and potential cost of boiling drinking water in urban Zambia

Boiling is the most common method of disinfecting water in the home and the benchmark against which other point-of-use water treatment is measured. In a six-week study in peri-urban Zambia, we assessed the microbiological effectiveness and potential cost of boiling among 49 households without a water connection who reported "always" or "almost always" boiling their water before drinking it. Source and household drinking water samples were compared weekly for thermotolerant coliforms (TTC), an indicator of fecal contamination. Demographics, costs, and other information were collected through surveys and structured observations. Drinking water samples taken at the household (geometric mean 7.2 TTC/100 mL, 95% CI, 5.4-9.7) were actually worse in microbiological quality than source water (geometric mean 4.0 TTC/100 mL, 95% CI, 3.1-5.1) (p < 0.001), although both are relatively low levels of contamination. Only 60% of drinking water samples were reported to have actually been boiled at the time of collection from the home, suggesting over-reporting and inconsistent compliance. However, these samples were of no higher microbiological quality. Evidence suggests that water quality deteriorated after boiling due to lack of residual protection and unsafe storage and handling. The potential cost of fuel or electricity for boiling was estimated at 5% and 7% of income, respectively. In this setting where microbiological water quality was relatively good at the source, safe-storage practices that minimize recontamination may be more effective in managing the risk of disease from drinking water at a fraction of the cost of boiling.     

Comparison of twice- and once-daily acidified boiling water cleaning of pipeline milking installations

Acidified boiling water (ABW) method, applied correctly on a twice- and once-daily basis, were compared on 15 farms in England and Wales during the winter of 1975/76. Treatments were applied in alternate months on each farm for six months, and during the once-daily treatment the second wash comprised a cold solution of sodium hypochlorite (250 mg/l available chlorine). Bacterio logical tests of both the milking equipment and the bulk milk showed no significant differences between the treatments. Continuous application of the once-daily method during a further three-month summer period on six farms showed mean bacterial colony counts to be higher in rinse samples but lower in milk samples compared with results previously obtained from the same farms for both treatments. The once-daily ABW treatment as monitored on one farm reduced the electricity costs for water heating by 45 per cent, which represented a saving of £28 per annum per milking unit.     

LonWorks技术在冷水站中的应用

研究了LonWorks现场总线技术在冷水站控制系统中的应用 .该系统的核心控制器为 2片Neuron 315 0芯片 ,分别组成DI和DO智能节点 .利用NodeBuilder开发工具在DI ,DO节点中分别定义 8个输出与 8个输入网络变量 ,由LonMaker对网络变量进行绑定操作 ,通过NenronC语言进行控制程序的开发 ,从而实现节点间的通信功能 .     

还原染料中汞的冷蒸气吸收法测定

探讨了微波消解后氢化物发生冷蒸气-原子吸收光谱法测定染料中汞的分析方法.比较了氯化亚锡和硼氢化钠分别作为还原剂测定汞含量的2种方法.结果表明:使用硼氢化钠作还原剂泡沫较少,但是存在共存离子干扰.最后选用氯化亚锡作还原剂,该方法的检出限为0.08 μg/L,回收率为95％～102％,线性范围为0～60 μg/L.