电感耦合等离子体质谱法测定石膏及其制品中铅、镉等10种元素

通过对进出口石膏及其制品特性的研究,摸索出适合石膏及其制品消解的方法,并对传统的仪器方法进行分析比较,最终确定了完整的检测路线。实验中试样经酸消解后过滤得到澄清溶液,用电感耦合等离子体质谱仪对试液中的铅、镉、铬、砷、汞、铜、锌、锰、镍、钴进行测定,10种元素的检出限和定量限分别为0.07mg/kg和0.2 mg/kg,加标回收率为87.0%-104.1%,相对标准偏差均小于10%。     

DUO-ICP-AES法同时测定不锈钢食具容器中铅、镉、铬、镍、砷的溶出量

采用DUO-ICP-AES同时测定不锈钢食具容器中铅、镉、铬、镍、砷的溶出量,对4%醋酸溶液中仪器的分析线选择、背景校正、入射功率、雾化器压力、辅助气流量、冷却气流量、蠕动泵转速的影响及共存元素的干扰等因素进行了详细的研究.方法的检测限:铅0.0063m/L;镉0.0009m/L;铬0.0018mg/L;镍0.0012mg/L;砷0.015mg/L,方法的回收率和精密度分别为96.4%～100.0%和0.31%～2.1%.该方法快速简便,具有良好的精密度和准确度,适用于进出口不锈钢食具容器的日常检验.     

电感耦合等离子体原子发射光谱法测定聚乙烯、聚丙烯中铬、锆、钒和铪

采用微波消解技术对以聚乙烯、聚丙烯为原料制作的食品容器、食品包装薄膜进行预处理,确定了溶样酸介质及其用量、微波消解温度、时间等关键因素,建立了一种快速测定聚乙烯、聚丙烯材料中铬、锆、钒和铪含量的电感耦合等离子体原子发射光谱法。实验结果表明,5mL硝酸和1mL过氧化氢的混合溶液即可实现样品的完全消解,同时通过优化光谱分析条件,得到铬、锆、钒和铪的检测限分别为1.0 mg/kg,0.7mg/kg,0.7 mg/kg,1.4 mg/kg。该法加标回收率在88%-103%之间,相对标准偏差（n=3）为0.84-6.4%。用于实际样品的测定,所得结果与标准样品的参考值相符。     

微波消解电感耦合等离子质谱法测定银耳中元素

建立了微波消解-电感耦合等离子体质谱(ICP-MS)同时测定银耳中镁、钙、铬、锰、铁、铜、锌、砷、硒、镉、汞、铅等12种元素的分析方法。样品经微波消解,通过在线加入内标校正基体干扰,采用干扰校正方程校正质量数干扰,各元素工作曲线相关系数均大于0.9995。所有待测元素的相对标准偏差RSD(n=6)均小于5%,加标回收率为90.0%-105.0%。通过对国家标准物质绿茶(GBW10052)和辽宁大米(GBW10043)进行验证,测定值与标准值相符。该方法具有准确、快速、灵敏度高等优点,适用于银耳中12种元素的同时测定。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定出口食品级磷酸中铜、镍、铅、锰、镉、钛

【目的】建立快速、准确并可同时测定食品级磷酸中铜、镍、铅、锰、镉、钛含量的方法。【方法】食品级磷酸样品直接稀释20倍后,用ICP—AES仪测定溶液中待测元素特征谱线的强度,采用标准品加入法定量。【结果】本方法测定食品级磷酸中铜、镍、铅、镉、钛的测定低限为1mg／kg,锰的测定低限为0．1mg／kg。室间相对标准偏差RSD〈13％,各项回收率85%-112％。【结论】能够满足出入境检验检疫实验室以及企业产品质量把关对食品磷酸中多种金属含量的一次性测定的需要。     

ICP-MS测定50种市售大米中铅、砷、镉、铬、汞的方法研究以及风险评估

应用微波消解-电感耦合等离子体质谱法(ICP-MS)同时测定大米中铅、砷、镉、铬、汞5种重金属含量。实验结果表明:5种元素标准曲线相关系数均大于0.999 8,精密度实验的RSD小于5%,加标回收率在76%～102%,检出限均低于0.02 mg·kg~(-1)。基于该方法得到的检测结果结合FAO/WHO规定的每日允许摄入量(ADI)、暂定每日可耐受摄入量(PMTDI)以及健康风险指数(RI)对50种市售大米样品进行重金属暴露健康风险评估均低于相关限量标准,处于安全水平。     

微波消解-FI-HG-AAS法测定中药材中汞和砷含量的研究

[目的]建立快速、准确地测定中药材中汞和砷含量的方法.[方法]微波消解处理样品,流动注射-氢化物发生-原子吸收法检测.[结果]汞在0.002 mg/L～0.02 mg/L浓度范围内线形良好,检出限为0.0004mg/L;砷在0.02 mg/L～0.16 mg/L浓度范围内线形良好,检出限为0.001mg/L,相关系数均大于0.99990;汞的回收率在85.0%～93.8%,砷的回收率在89.4%～102.0%,相对标准偏差分别为5.5%和4.1%.[结论]该方法省时、节能、准确度高.     

X射线荧光光谱法定性和定量筛选电子电气产品中铅、汞、铬、镉和溴

本文提出了用X射线荧光光谱法定性和定量筛选电子电气设备中限制使用物质铅、汞、铬、镉和溴的一种新的测试方法.方法研究了金属材料基体、聚合物基体和不同电子产品等对待测元素的基体影响,研究了基体、元素间的谱线重叠所产生的光谱干扰.考察了样品大小不同和样品厚度不同对待测元素测试结果的影响,并选用Rh线的康普顿散射线作内标来校正这些非光谱干扰的影响.方法选用有证标准物质制作工作曲线,各待测元素的浓度范围从0.1mg/Kg到200rg/Kg,均获得非常好的线性关系,选用有证标准物质BCR-681,并设置100s测量时间来计算铅、汞、铬、镉和溴的最低检出限,其检出限分别为PbL(0.64mg/Kg、Hg L(0.51mg/Kg、Cr K(0.78mg/Kg、Cd K(1.10mg/Kg和Br K(0.27mg/Kg.以BCR-681作为实际样品进行测试,其结果与标准推荐值非常吻合.     

普洱茶中重金属元素砷铅镉铬汞铜的含量测定及风险评价

采用电感耦合等离子体质谱法(ICP-MS)对普洱市辖区内购买的100批普洱茶进行砷、铅、镉、铬、汞和铜6种重金属含量检测,了解这6种金属元素在各县区茶叶中的富集情况并进行风险评价,为保障茶叶质量安全提供数据支撑。GB 2762-2017《食品安全国家标准食品中污染物限量》规定茶叶中铅限量标准为5.0 mg·kg~(-1);农业部标准NY 659-2003《茶叶中铬、镉、汞、砷及氟化物限量》、NY 5196-2002《有机茶》规定茶叶中镉、铬、汞、砷、铜限量标准分别为1、5、0.3、2 mg·kg~(-1)和30 mg·kg~(-1)。在所有检出的茶叶样品中,总砷含量为0.001～0.300 mg·kg~(-1),铅含量为0.003～0.600 mg·kg~(-1),镉含量为0.004～0.090 mg·kg~(-1),铬含量为0.07～1.00 mg·kg~(-1),总汞含量为0.005～0.100 mg·kg~(-1),铜含量为14～32 mg·kg~(-1),除思茅区的1个样品铜元素含量为32 mg·kg~(-1),超出临界值外,其他元素含量均不超国家限量标准。     

微波消解-电感耦合等离子体质谱法测定六堡虫茶中的6种重金属含量

六堡虫茶试样经微波消解后,采用电感耦合等离子体质谱法(ICP-MS)测定其中的铅、砷、汞、镉、铬和铜6种重金属含量。结果表明,方法加标回收率在93.2%～104.7%,相对标准偏差在0.67%～4.35%。本方法简单快速、准确度高、重复性及稳定性良好,是检测六堡虫茶中重金属元素的一种有效分析方法,为六堡虫茶的质量控制及安全性提供科学依据。     

China and Africa, Fiendship, Pace,Cooperation and Dvelopment

The Forum of China-Africa Cooperation（FOCAC）.was held in Nowember, as well as the The 2nd Sino-African Entrepreneurs Conference ,marking the milestone of the China-Africa relations which have experienced the test of several thousand years,     

HOPE,FEAR, AND ASPIRATIONS

We propose a rank‐dependent portfolio choice model in continuous time that captures the role in decision making of three emotions: hope, fear, and aspirations. Hope and fear are modeled through an inverse‐S shaped probability weighting function and aspirations through a probabilistic constraint. By employing the recently developed approach of quantile formulation, we solve the portfolio choice problem both thoroughly and analytically. These solutions motivate us to introduce a fear index, a hope index, and a lottery‐likeness index to quantify the impacts of three emotions, respectively, on investment behavior. We find that a sufficiently high level of fear endogenously necessitates portfolio insurance. On the other hand, hope is reflected in the agent's perspective on good states of the world: a higher level of hope causes the agent to include more scenarios under the notion of good states and leads to greater payoffs in sufficiently good states. Finally, an exceedingly high level of aspirations results in the construction of a lottery‐type payoff, indicating that the agent needs to enter into a pure gamble in order to achieve his goal. We also conduct numerical experiments to demonstrate our findings.     

SUPPLY CHAIN MANAGEMENT AND ITS RELATIONSHIP TO LOGISTICS,MARKETING, PRODUCTION,AND OPERATIONS MANAGEMENT

The renaming of the Council of Logistics Management (CLM) to the Council of Supply Chain Management Professionals (CSCMP) ushered in some interesting definitional dialogue and debate within the practitioner and academic communities. Inherent in emerging definitions is the notion that SCM encompasses activities traditionally considered aspects of production, logistics, marketing, and operations management. Defining SCM in such a broad scope (i.e., a “within” and “across” functions perspective), while considered by many scholars as the true representation of the essence of SCM, creates confusion regarding the appropriate organizational level within a business that is best suited for managerial decision making regarding the phenomenon. This paper contributes to the emerging SCM dialogue by highlighting the functional spaces (the “within” function perspective), relationships, and conceptual overlaps (the “across” functions perspective) between marketing, logistics, production, operations, and supply chain management. By comparing and contrasting the literature‐based conceptual boundaries of each discipline, a framework is proposed that more clearly captures the essence of the SCM decision making sphere. Managerial insights and future research implications are presented.     

蒂芙尼,地位与财富的象征

那是一种很特殊的蓝,温柔地透着幸福的光彩,打开盒子上面的白色缎带,眼睛中的光芒映射出钻石的华彩。“嫁给我吧”,这是最悦耳的话语,一种爱的承诺被牢牢地攥在手中。最近,身边经常传来结婚的喜讯,让人也被一种满满的幸福所包围,不由想起了蒂芙尼（Tiffany）,想起了它经典的订婚钻戒。虽然没有卡地亚的豪华,但是蒂芙尼有着美国式的简洁、明朗,每件作品带着美国人与生俱来的直率、乐观和乍现的机智。     

DISUTILITY, OPTIMAL RETIREMENT, AND PORTFOLIO SELECTION

We study the optimal retirement and consumption/investment choice of an infinitely-lived economic agent with a time-separable von Neumann–Morgenstern utility. A particular aspect of our problem is that the agent has a retirement option. Before retirement the agent receives labor income but suffers a utility loss from labor. By retiring, he avoids the utility loss but gives up labor income. We show that the agent retires optimally if his wealth exceeds a certain critical level. We also show that the agent consumes less and invests more in risky assets when he has an option to retire than he would in the absence of such an option.
An explicit solution can be provided by solving a free boundary value problem. In particular, the critical wealth level and the optimal consumption and portfolio policy are provided in explicit forms.     

BESSEL PROCESSES, ASIAN OPTIONS, AND PERPETUITIES

Using Bessel processes, one can solve several open problems involving the integral of an exponential of Brownian motion. This point will be illustrated with three examples. The first one is a formula for the Laplace transform of an Asian option which is "out of the money." The second example concerns volatility misspecification in portfolio insurance strategies, when the stochastic volatility is represented by the Hull and White model. The third one is the valuation of perpetuities or annuities under stochastic interest rates within the Cox-Ingersoll-Ross framework. Moreover, without using time changes or Bessel processes, but only simple probabilistic methods, we obtain further results about Asian options: the computation of the moments of all orders of an arithmetic average of geometric Brownian motion; the property that, in contrast with most of what has been written so far, the Asian option may be more expensive than the standard option (e.g., options on currencies or oil spreads); and a simple, closed-form expression of the Asian option price when the option is "in the money," thereby illuminating the impact on the Asian option price of the revealed underlying asset price as time goes by. This formula has an interesting resemblance with the Black-Scholes formula, even though the comparison cannot be carried too far.     

CONSUMER PROTECTION,CONSUMERS AND BUSINESS

This paper is based on a speech given to an OYEZ-IBC Conference in London on 10 November 1979. It argues that U.K. consumers and business generally have benefited from recent changes in the law. The ‘backlash’ against consumer protection legislation by some elements in business is wholly misguided.     

GROWTH,STAGNATION AND STATUS PREFERENCE

We show that an economy grows or stagnates depending on which of three objects people most esteem as tokens of status. If the main object of status preference is consumption, then a steady state with full employment is reached. If it is physical capital (which is a producible asset), then permanent growth with full employment occurs. However, if it is money (which is not a producible asset), stagnation with persistent unemployment arises.     

CAPITALISTS,WORKERS AND SOCIAL SECURITY

This paper elaborates an exogenous growth model that nests overlapping generations of workers who save for life cycle reasons with dynastic agents who save for bequest reasons (‘capitalists’). The model overcomes Marglin's objection that the overlapping generations framework requires special assumptions about technology, and it also provides a natural environment to revisit Samuelson's analysis of lump‐sum transfers between generations. The ability of a benevolent planner to improve workers' welfare is severely restricted by the control capitalists exercise over the accumulation process. Prefunding social security assumes renewed significance because it overcomes this restriction.