蓝宝石玻璃超声振动辅助磨削试验研究

为了探究烧结磨头不同磨头参数和磨削参数对蓝宝石玻璃磨削特性的影响,综合考虑了磨头粒度号、主轴转速、进给速度、磨削深度等因素,设计并开展了非超声和超声振动辅助磨削加工试验,研究了上述因素对蓝宝石磨削表面粗糙度、表面形貌及磨削力的影响。结果表明,超声和非超声磨削工况中,磨头粒度号增大对磨削力和表面粗糙度的影响整体均呈现先增大后减小的趋势。不同磨头粒度号工况下的超声磨削力和表面粗糙度普遍小于非超声结果,磨削力最大降幅为27.2%,表面粗糙度最大降幅为18.6%;采用粒度号200/230#的磨头进行磨削,可获得相对较小的切削力和表面粗糙度,是研究工况下的最佳粒度号,而140/170#的使用效果最差。相比于非超声磨削,超声可在所选的主轴转速、进给速度和磨削深度条件下实现磨削力和表面粗糙度不同程度的降低,在小主轴转速和小磨削深度工况下,超声磨削对蓝宝石表面质量的改善作用更显著。

超声滚压工艺对6061铝合金表层特性的影响研究

为了系统地探究超声滚压工艺对6061铝合金表层特性的影响,设计了三因素三水平正交实验,分析在不同超声滚压加工参数(主轴转速、进给速度以及往复次数)下对工件表面粗糙度、晶粒尺寸以及表面硬度的影响。结果表明:工件的表面粗糙度随着不同加工参数的增加先降低后增大;工件的表面晶粒尺寸随着主轴转速和往复次数的增加先降低后变大,进给速度对其影响较小;工件的表面硬度随着主轴转速和往复次数的增加先增大后减小,随着进给速度先减小后增大。在3个影响因素中,主轴转速对6061铝合金表面晶粒尺寸、表面硬度、表面粗糙度的影响最大,其次为往复次数和进给速度。

Analysis of Total Antimony in Fresh Fruit and Pollution Evaluation in Hunan Province

[ Objective] The content of total antimony （Sb） in fresh fruit was investigated and its pollution was evaluated, to provide the basic data for diet exposure evaluation. [ Method] The content of total Sb in 194 samples was detected by hydride generation-atomic fluorescence spectrometry （HG-AFS）, and the Sb pollution in several fruits was evaluated by the method of single factor pollution index. [ Result ] The mean of total Sb was 0. 005 6 mg/kg, and the median was 0.003 8 mg/kg. The minimum value was not detected while the maximum value was O. 21 mg/kg, and the confidence interval was ND-O. 019 mg/kg （PS-P95）. The medi- ans of total Sb content in different fruits successively were dragon fruit （0.011 0 mg/kg） 〉 kiwi fruit （0.008 0 mg/kg） 〉 peach （0.006 0 mg/kg）. According to the method of single factor pollution index, the index from all samples was less than 0.2, suggesting that the samples involved were under the normal background value. [ Conclusion ] The Sb was detected in all samples but under the background value, and it was concluded that there was no Sb pollution in fresh fruit in Hunan Province.

Spatial and Temporal Distribution of Total Antimony Content in Fresh Vegetables in Hunan Province

[Objective] The purpose of this paper is paper was to master the spatial and temporal distribution of total antimony content in fresh vegetables in Hu- nan Province. [ Method ] Fresh vegetable samples were collected in 14 areas of Hunan Province and Xikuangshan Street. The content of antimony was detected by Hydride Generation-atomic fluorescence spectrometry. The spatial and temporal distribution of total antimony in fresh vegetables in different areas and seasons were compared. [Result] In 703 vegetable samples, the reference range （P5-195） of total antimony content was ND -0.25mg/kg, and the median was 0. 018 mg/kg; and the median of total antimony content in Xiangtan City and Xikuangshan Street were 0.046 and 0.041 mg/kg respectively, significantly higher than those in other areas. The differences among groups were statistically significant （ P 〈 0. 05 ）. The reference range of total antimony content in spring samples was ND -0.24 mg/kg, and the median was 0. 023mg/kg; the reference range of total antimony in autumn samples was ND -0. 088mg/kg, and the median was 0.007 4 mg/kg. [ CondusionJ The reference range of total antimony content in Hunan Province is ND -0.25mg/kg, and the median is 0.018 mg/kg. The con- tent of total antimony content in Xiangtan City and Xikiangshan Street is higher. And the total antimony content in spring samples are higher than those in autumn samples.

亚洲共同体

陶丹(以下简称“陶”):你以前是学经济出生,这样的学历背景和知识准备对你后来做画廊有没有影响或者说帮助?因为经济学的背景,至少方便在财务上进行掌控。会比学艺术的更理性一些。而且我们自然会学到商业,包括如何去经营。对于画廊而言。经营是非常重要的工作。就这方面而言,我觉得当我去从事画廊业会比学艺术的具备更多有利的条件。

湖南不同地区居民锑的膳食暴露水平及地理分布趋势分析

目的掌握湖南不同地区居民总锑的膳食暴露水平及地理分布趋势。方法收集2014—2016年湖南省14地州市食品样品1 586份,样品取可食部分切碎、粉碎(匀浆)、混匀后称取试样0.5~1 g(精确至0.001 g)于微波消解罐内,加4 m L浓硝酸和2 m L 30%过氧化氢,放置30 min后,密闭旋紧内罐置于微波炉内,调节升温程序进行消解,其消解液采用AFS-230E型双道原子荧光光度计进行荧光强度测定,通过标准曲线法计算样品中总锑含量。将食品中锑含量×居民食物每日摄入量/标准人体重,计算得出各地区居民每人每日单位体重锑的平均膳食暴露量(居民食物摄入量数据源自《湖南省常住居民营养与健康状况现状分析》)。再取每个地区中心位置的经度和纬度值作为坐标值(x,y),使用Suffer 8.0软件把拟合的最优趋势方程得出的各地区居民锑的膳食暴露趋势数据和坐标数据,绘制趋势分析等值线图,分析其地理分布趋势特征。结果湖南各区域食品中总锑含量中位数由高到低分别为湘中(0.021 0 mg/kg)、湘北(0.009 2 mg/kg)、湘东(0.009 0 mg/kg)、湘南(0.007 8 mg/kg)和湘西(0.007 7 mg/kg)。湘东、湘南、湘中、湘西和湘北地区的居民锑膳食平均暴露量分别为1.19、0.90、0.75、0.55、0.40μg/(kg·BW)。结论湖南东部地区居民膳食锑的暴露量明显偏高,并且在湘东、湘中地区均有高峰值出现,其他区域都处于一个相对较低范围。