Nanoscale Insight Into Lead‐Free BNT‐BT‐xKNN

Piezoresponse force microscopy (PFM) is used to afford insight into the nanoscale electromechanical behavior of lead‐free piezoceramics. Materials based on Bi_1/2Na_1/2TiO₃ exhibit high strains mediated by a field‐induced phase transition. Using the band excitation technique the initial domain morphology, the poling behavior, the switching behavior, and the time‐dependent phase stability in the pseudo‐ternary system (1–x)(0.94Bi_1/2Na_1/2TiO₃‐0.06BaTiO₃)‐xK_0.5Na_0.5NbO₃ (0 <= x <= 18 mol%) are revealed. In the base material (x = 0 mol%), macroscopic domains and ferroelectric switching can be induced from the initial relaxor state with sufficiently high electric field, yielding large macroscopic remanent strain and polarization. The addition of KNN increases the threshold field required to induce long range order and decreases the stability thereof. For x = 3 mol% the field‐induced domains relax completely, which is also reflected in zero macroscopic remanence. Eventually, no long range order can be induced for x >= 3 mol%. This PFM study provides a novel perspective on the interplay between macroscopic and nanoscopic material properties in bulk lead‐free piezoceramics.     

In和Te掺杂PbSe薄膜制备及其对薄膜光电性能的影响机制

采用中频磁控溅射技术制备了PbSeIn和PbSeTe两种掺杂PbSe薄膜, 并采用理论模拟与实际实验相结合的方法研究了In和Te两种元素的掺杂机制及其对薄膜性 能的影响。结果表明,In原子主要通过置换Pb原子的形式进行掺杂,而Te原子则主要置换 Se原子;与未掺杂PbSe薄膜相比,PbSeIn和PbSeTe两种薄膜的光电敏感性均有一定提高, 其中In掺杂PbSe薄膜的平均电阻变化率最高。这是由于In元素在PbSe薄膜禁带内形成深杂 质能级,提高非平衡载流子寿命所导致的。而PbSeTe薄膜的光电敏感性则与未掺杂PbSe薄 膜相近。     

从氯化铅渣中回收铅铋的研究

本文以柿竹园有色金属矿粗铋火法精炼、气化除铅产出的铅渣为原料，在常压下采用氯化钠水溶液进行浸出处理，有效地分离了铅和铋，并将铅制成了化工产品黄丹及硫酸铅     

硫酸中Pb－PbO_2阳极的电催化性能

本文对铅及Ｐｂ－ＰｂＯ２在硫酸溶液中作为析氧阳极的特性进行了研究。考察了Ｐｂ－ＰｂＯ２阳极在２．５ｍｏｌ／ＬＨ２ＳＯ４中电解使用寿命，测定了铅和Ｐｂ－ＰｂＯ２阳极的极化曲线和电化学动力学参数（ａ、ｂ和ｉ０），结果表明Ｐｂ－ＰｂＯ２电极比铅电极的电催化性能优良。     

国家标准方法测定铅精矿中铅的不确定度评定

本文对国家标准方法酸溶解-EDTA滴定法测定铅精矿中铅量的测量不确定度来源进行了分析,对Na2EDTA标准溶液的滴定度、滴定体积、不溶渣和滤液中铅量的测定、试样的质量、测试过程随机误差等不确定度分量进行了分析和量化,求得合成标准不确定度和扩展不确定度分别为0.11%和0.22%。     

快速无铅五香皮蛋的研制

以优质鸡蛋为原料,经无铅加五香料的适宜碱度的料夜浸泡,以保鲜膜包装后,在适宜条件下后熟,快速生产具有美观色泽、独特的风味、营养丰富的溏心鸡皮蛋。     

Trace elements in Canadian field peas: a grain safety assurance perspective

Canada is a significant exporter of field peas and, thus, issues of food safety are important in all grain and food products within the international marketplace. Environmental contaminants, such as trace elements, may be present in all foods and, as a result, international standards have been established for a number of toxic trace elements, such as cadmium, lead, mercury and arsenic, in raw food commodities and food products. The Canadian Grain Commission has undertaken a baseline study of various trace elements in Canadian peas to ensure compliance with international food safety legislation. Mean total cadmium content was found to be 0.023 mg kg^?1; arsenic and lead mean values were below the method limit of quantification of 0.050 mg kg^?1 and the total mean mercury level was below the quantification level of 0.002 mg kg^?1. All measured values in the study were below the maximum residue levels (MRLs) established by the FAO and WHO in the Codex Alimentarius. The mean total selenium content was 0.331 mg kg^?1, with 56% of the measured values exceeding the MRL established by the People's Republic of China (PRC) of 0.3 mg kg^?1. No Codex MRL has been established for selenium as it is regarded as an essential trace element for human health and the PRC is currently reviewing its MRL for selenium in light of this fact. For those parts of the world where selenium-deficiency is of nutritional concern, the higher level of selenium in Canadian peas and their products may be of nutritional benefit.     

溴百里香酚蓝作指示剂原子荧光光谱法测定食品中的铅

研究了氢化物原子荧光光谱法测定食品中铅的酸度控制.对样品溶液进行酸度调节后补加酸的方法来准确控制酸度,并确定样品溶液的最佳酸度为0.18mol/L,铅的浓度在5～4 0μg/L范围内呈现线性,相关系数达0.9999,RSD为0.22%,检出限为0.1 5μg/L,回收率为98.3%～104.6%.所拟方法用于米粉、奶粉、橡子淀粉、木耳、香菇等样品测定,结果满意.     

Removal of Cadmium and Lead from Aqueous Solution by Enterococcus faecium Strains

ABSTRACT:  Foods may be contaminated with heavy metals, which, even in small quantities, possess detrimental effects on human health. The aim of the present study was to investigate the uptake of cadmium or lead from an aqueous medium frequently found in foods, by 2  Enterococcus faecium  strains ( E. faecium  EF031 and  E. faecium  M74). Also, the effects of the bacterial viability, incubation (contact) time, and pH on the binding capacities and binding stability were assessed. The results showed that both of the strains efficiently removed cadmium and lead. While EF031 removed 77.3% to 98.1% of cadmium and 66.9% to 98.9% of lead, M74 removed 53.5% to 91% of cadmium and 42.9% to 93.1% of lead throughout a 48 h incubation period at pH 5. It was found that, at 1 h, EF031 and M74 strains removed cadmium and lead, which was more than 60% of total removed cadmium and lead throughout the whole incubation period of 48 h. It suggests that the uptake of cadmium and lead by EF031 and M74 strains is a rapid process. The binding of both heavy metals increased with increasing pH of an aqueous medium and was the highest at pH 5. Also, the complexes formed between both heavy metals and bacterial cells were found to be stable. These findings indicate that  E. faecium  strains used in the study are able to bind the 2 heavy metals and may be used in the production of fermented functional foods, which will be healthy via its detoxification properties.