微波消解-电感耦合等离子体质谱(ICP-MS)法测定纳米银抗菌产品中多种微量元素

建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定4种纳米银抗菌产品中多种微量元素的分析方法。比较了湿法消解和微波消解这两种样品前处理方法对样品测定的影响,探讨了消除汞记忆效应的方法,并研究了待测元素的质谱干扰的消除。实验结果表明,采用Au(100μg/L)+HCl(2%)能较好地消除Hg的记忆效应。与湿法消解相比,微波消解可短时间消解样品并获得好的Hg回收率。在优化ICP-MS条件后,各元素线性相关系数均大于0.999。采用微波消解-ICP-MS法对样品进行加标回收,样品加标回收率在84.0%~109%,相对标准偏差在0.97%~13.2%。方法快速、简便,能够满足纳米银抗菌产品中微量元素的定量测定。     

基于乘积季节模型的社会消费品零售总额分析

社会消费品零售总额是反映人们消费水平的重要度量指标,也是国民经济体系中的一个重要评价指标.因此,分析研究社会消费品零售总额发展趋势对于转型期的中国经济高质量发展具有重要意义.基于乘积季节模型对2001年至2020年的社会消费品零售总额数据进行时间序列分析,经过差分、单位根检验、模型识别与拟合等过程,确定最终模型为ARI...     

Weibull分布在新产品市场渗透研究中的应用拓展

在应用Weibull模型研究新产品市场渗透时,"永不采用人群"、消费者个体之间的差异、消费者群体之间的差异是研究新产品采用时需要考虑的三种因素。本文基于这三种因素分别建立了三个拓展的Weibull模型,并利用面板数据进行了实证研究,发现三种拓展之后的模型在数据拟合和数据预测方面均有显著的提高.然后,本文将三种因素整合至一个模型之中形成了一种新的综合Weibull模型,实证分析结果显示新的模型有很好的新产品市场渗透数据拟合和预测能力.     

基于不同政府补贴策略的供应链绿色努力决策比较研究

研究由单一制造商与单一零售商组成的二级绿色供应链,探讨在同时考虑制造商与零售商绿色努力情况下政府补贴策略对供应链绿色努力与定价决策的影响,比较分析无补贴策略、制造商补贴策略与消费者补贴策略对决策影响的差异性,并进一步考虑零售商的风险规避特征对最优决策的影响。结果表明,政府补贴能够激励制造商与零售商的绿色努力行为,对供应链的绿色发展总是有利的;且制造商补贴策略下的绿色质量水平高于消费者补贴策略,但对供应链利润而言并不是最优的;而在消费者补贴策略下,尽管产品的绿色质量水平不是最优的,但供应链可以获得最高的利润。研究还发现,风险规避特征不会改变参数对最优决策与最优利润的影响趋势,但会降低零售商的绿色努力积极性,导致其利润的下降。     

基于消费者偏好的低碳双渠道供应链定价与减排策略

在考虑消费者渠道偏好和低碳偏好的基础上,使用以制造商为主的Stackelberg博弈模型,研究了单一传统零售渠道、网上直销双渠道和网上分销双渠道中各成员的最优定价决策与减排策略,以及两种双渠道的利润分享协调策略。研究发现:当制造商引入网上直销和分销渠道后,能够有效增加制造商的最优单位减排量;在开通新的渠道后,传统零售商的利润总是会降低,而当消费者对网上销售渠道的偏好处于某一范围内时,制造商的利润会增加。本文通过设计利润分享机制来协调制造商和传统零售商的利润问题,使得供应链成员的利润实现Pareto改进。     

Omnichannel operations with ship-from-store

While embracing omnichannel operations, firms are rolling out ship-from-store (SFS). This paper considers a newsvendor-like retailer operating both online and offline channels, and analyzes how SFS affects the seller’s profits. In our model, consumers strategically choose a channel to optimize their utility, which is investigated by applying the theory of hyperbolic discounting. The results show that, interestingly, the firm can be worse off implementing SFS, when the customer-base expansion thanks to SFS is not significant.     

Re‐Gradation of Photo‐Oxidized Post‐Consumer Greenhouse Films

Summary: The degradation undergone by the polymers during their use and because of the thermo‐mechanical degradation undergone during the reprocessing operations provokes, among other effects, the decrease of the molecular weight. The change of the molecular architecture is responsible for the deterioration of all the properties. In order to restore the properties of post‐consumer recycled plastics, some rebuilding of the molecular structure is necessary. In this work, photo‐oxidized films for greenhouses were reprocessed in presence of additives able to react with the polyethylene in order to form branching and cross‐linking, improving the properties of these post‐consumer plastic.

Pressure as a function of time in the mini twin‐screw extruder, processing speed 70 rpm.     

Identification of Non-Volatile Compounds That Impact Flavor Disliking of Whole Wheat Bread Made with Aged Flours

Whole wheat flour has a shorter shelf life than refined wheat flour due to off-flavor development. An untargeted liquid chromatography/mass spectrometry (LC/MS) flavoromics approach was applied to identify compounds that negatively impact the flavor liking in whole wheat bread made from aged flours. The chemical profiles of thirteen breads made from aged flours were obtained using LC/MS and modeled by orthogonal partial least squares (OPLS) to predict flavor liking. Top predictive chemical features (negatively correlated) were identified as pinellic acid (9S,12S,13S-trihydroxy-10E-octadecenoic acid), 12,13-dihydroxy-9Z-octadecenoic acid, and 1-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine. The sensory analysis confirmed the three compounds increased the bitterness intensity of the bread samples. The formation of the trihydroxy fatty acid bitter compound, pinellic acid (9S,12S,13S-trihydroxy-10E-octadecenoic acid), was impacted by the lipoxygenase activity of the flour; however, there was no influence on the formation of 12,13-dihydroxy-9Z-octadecenoic acid or 1-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine. Additionally, the concentrations of all bitter compounds were significantly higher in bread made from aged flour versus non-aged flour.     

Optimizing fleet size and delivery scheduling for multi-temperature food distribution

In light of the demand for high-quality fresh food, transportation requirements for fresh food delivery have been continuously increasing in urban areas. Jointly delivering foods with different temperature-control requirements is an important issue for urban logistic carriers who transport both low temperature-controlled foods and normal merchandise. This study aims to analyze and optimize medium- and short-term operation planning for multi-temperature food transportation. For medium-term planning, this study optimizes fleet size for carriers considering time-dependent multi-temperature food demand. For short-term planning, this study optimizes vehicle loads and departure times from the terminal for each order of multi-temperature food, taking the fleet size decided during medium-term planning into account. The results suggest that carriers determine departure times of multi-temperature food with demand–supply interaction and deliver food of medium temperature ranges with priority because delivering such food yields more profit.     

Diet–consumer nitrogen isotope fractionation for prolonged fasting arthropods

Nitrogen acquisition for cellular metabolism during diapause is a primary concern for herbivorous arthropods. Analyses of naturally occurring stable isotopes of nitrogen help elucidate the mechanism. Relevant articles have cited (58 times up to mid-June 2011) anomalously elevated δ¹⁵N (per mil deviation of ¹⁵N/¹⁴N, relative to atmospheric nitrogen=0 ‰) values (diet–consumer nitrogen isotope fractionation; up to 12 ‰) for a prolonged fasting raspberry beetle (Byturus tomentosus Degeer (Coleoptera: Byturidae)), which feeds on red raspberries (Rubus idaeus: δ¹⁵N=～+2 ‰). Biologists have hypothesised that extensive recycling of amino acid nitrogen is responsible for the prolonged fasting. Since this hypothesis was proposed in 1995, scientists have integrated biochemical and molecular knowledge to support the mechanism of prolonged diapausing of animals. To test the validity of the recycling hypothesis, we analysed tissue nitrogen isotope ratios for four Japanese arthropods: the shield bug Parastrachia japonensis Scott (Hemiptera: Cydnidae), the burrower bug Canthophorus niveimarginatus Scott (Hemiptera: Cydnidae), leaf beetle Gastrophysa atrocyanea Motschulsky (Coleoptera: Chrysomelidae) and the Japanese oak silkworm Antheraea yamamai (Lepidoptera: Saturniidae), all of which fast for more than 6 months as part of their life-history strategy. Resulting diet–consumer nitrogen isotope discrimination during fasting ranged from 0 to 7‰, as in many commonly known terrestrial arthropods. We conclude that prolonged fasting of arthropods does not always result in anomalous diet–consumer nitrogen isotope fractionation, since the recycling process is closed or nearly closed with respect to nitrogen isotopes.