Nanoparticles of the Lead-free Solder Alloy Sn-3.0Ag-0.5Cu with Large Melting Temperature Depression

Due to the toxicity of lead (Pb), Pb-containing solder alloys are being phased out from the electronics industry. This has lead to the development and implementation of lead-free solders. Being an environmentally compatible material, the lead-free Sn-3.0Ag-0.5Cu (wt.%) solder alloy is considered to be one of the most promising alternatives to replace the traditionally used Sn-Pb solders. This alloy composition possesses, however, some weaknesses, mainly as a result of its higher melting temperature compared with the Sn-Pb solders. A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy particle size down to the nanometer range. The melting temperature of Sn-3.0Ag-0.5Cu lead-free solder alloy, both as bulk and nanoparticles, was investigated. The nanoparticles were manufactured using the self-developed consumable-electrode direct current arc (CDCA) technique. The melting temperature of the nanoparticles, with an average size of 30 nm, was found to be 213.9°C, which is approximately 10°C lower than that of the bulk alloy. The developed CDCA technique is therefore a promising method to manufacture nanometer-sized solder alloy particles with lower melting temperature compared with the bulk alloy.     

Accuracy of the zero crossings of the second directional derivative as an edge detector

In this paper the accuracy of the second directional derivative edge detector is analyzed, based on a number of idealized edge models. The results are compared with those for the Laplacian edge detector. Errors are shown to be small under a number of conditions. These conditions are less severe for the second directional derivative than for the Laplacian edge detector. Spurious or phantom edges can be removed by checking the sign of the third directional derivative, though this is not enough to remove all large errors. Indeed, it is also shown that large errors will be obtained if no threshold is set on the magnitude of a third order derivative.This work was supported by the Belgian National Fund for Scientific Research (NFWO).     

在减少碳足迹的道路上——Stora Enso集团减少碳足迹实例

近年来,为了人类的可持续发展和应对全球气候变暖,减少碳排放及发展低碳经济已成为全球共识。林纸产品行业在遏制气候变化方面握有先机,可持续森林和人工林管理在减缓气候变化方面发挥着重要作用。     

The extreme xerophilic mould Xeromyces bisporus--growth and competition at various water activities

Little is known about the mould, Xeromyces bisporus, unique in its strong xerophilicity and ability to grow at water activity (a_w) 0.62, lower than for any other known organism. The linear growth rates of one fast and one slow-growing strain of X. bisporus were assessed at 20, 25, 30 and 37 °C on solid agar media containing a mixture of glucose and fructose to reduce a_w to 0.94, 0.88, 0.84, 0.80, 0.76 and 0.66. Growth rates of xerophilic species closely related to X. bisporus, viz. Chrysosporium inops, C. xerophilum and Monascus eremophilus, were also assessed. Optimal conditions for growth of both X. bisporus strains were approx. 0.84 a_w and 30 °C, despite FRR 2347 growing two- to five-fold faster than CBS 185.75. X. bisporus FRR 2347 even grew well at 0.66 a_w (0.48 mm/day). C. inops and C. xerophilum were more tolerant of high a_w than X. bisporus, and could be differentiated from each other based on: the faster growth of C. xerophilum; its preference for temperatures ≥ 30 °C and a_w ≥ 0.94 (c.f. ≤ 25 °C and ~ 0.88 a_w for C. inops); and its ability to grow at 0.66 a_w, which is the lowest a_w reported to date for this species. M. eremophilus grew slowly (max. 0.4 mm/day) even in its optimal conditions of ~ 0.88 a_w and 25 °C. To investigate the competitive characteristics of X. bisporus at low a_w, both X. bisporus strains were grown in dual-culture with xerotolerant species Aspergillus flavus and Penicillium roqueforti, and xerophilic species A. penicillioides, C. inops, C. xerophilum and Eurotium chevalieri, on glucose-fructose agar plates at 0.94, 0.84, 0.80 and 0.76 a_w and at 25 °C. Growth rates and types of interactions were assessed. Excretion of inhibitory substances acting over a long-range was not observed by any species; inhibitors acting over a short-range that temporarily slowed competitors' growth or produced a protective zone around the colony were occasionally observed for A. penicillioides, C. inops and C. xerophilum. Instead, rapid growth relative to the competitor was the most common means of dominance. The xerotolerant species, A. flavus and P. roqueforti were dominant over X. bisporus at 0.94 a_w. E. chevalieri was often dominant due to its rapid growth over the entire a_w range. At a_w < 0.80, X. bisporus was competitive because it grew faster than the other species examined. This supports the concept that its ideal environmental niche is sugary foods with low a_w.     

消减食品加工过程中的真菌毒素：来自欧洲和东南亚的经验分享（网络首发、推荐阅读）

在世界范围内,由真菌毒素造成的经济损失估计达数十亿美元,给人类和动物带来安全风险。粮食中真菌毒素的预防可以通过食品加工过程中进行真菌毒素的消减处理。在过去几十年里,虽然发表的科技论文中报道了大量真菌毒素防控措施,但实际生产往往需要更容易实施的、简单易行的建议和指导方针。欧洲和东南亚在真菌毒素处理到数据分析、风险评估到污染防控、差异分析到流通途径等方面可以做到相互协作,互相补充。欧洲和东南亚政府及相关行业必须在综合考虑地域、农业系统和不同国家消费者偏好的背景下,寻求平衡食品安全和地区贸易二者关系,协同管控食品供应链。以谷物为例,加工过程包括初级加工（谷物清理和碾磨操作）和二次加工（如烘焙过程中的发酵和烘烤）,欧洲尤其关注烘焙食品安全性及全麦面包生产工艺对呕吐毒素的影响。结合农业、咖啡工业和科学研究人员的专业知识及亚洲咖啡生产者的具体情况,重点关注东南亚地区咖啡中赭曲霉毒素A污染问题。在农场环境中减少真菌毒素的措施给咖啡农民带来了较大的挑战,包括在规范种植农场模式下咖啡生产者和消费者之间社会经济效益和个人行为模式的相关影响因素。随着世界变得更加全球化,食品和饲料供应链也变得日趋复杂,因此,需要制定更全面的策略来确保食品供给及品质安全。     

Degradation of erythromycin in honey and selection of suitable marker residues for food safety analysis

Extra-label use of veterinary medications in apiculture is a practice which is known to result in the presence of drug residues in honey. Erythromycin has been used by some beekeepers in an attempt to control foulbrood diseases in honey bees. It is recognised that erythromycin degrades in acidic aqueous solutions to yield predominantly anhydroerythromycin. Honey is an acidic medium in which erythromycin should also degrade. Three degradation products with a molecular weight of 715 Da (anhydroerythromycin, erythromycin enol ether, and an unidentified but suspected related isomer) have been confirmed to be formed in honey. Erythromycin was found to degrade rapidly in honey at typical hive temperature with a half-life of less than one day. Based on these results, it is recommended that food safety laboratories include degradation products in analytical testing protocols when examining honey for erythromycin residues.     

Development and validation of a new LC–MS/MS method for the simultaneous determination of six major ergot alkaloids and their corresponding epimers. Application to some food and feed commodities

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous determination of six major ergot alkaloids, ergometrine, ergosine, ergotamine, ergocornine, ergokryptine and ergocristine, as well as their corresponding epimers in food and feed samples. The method involves extraction under alkaline conditions and subsequent clean-up by applying a simple and rapid liquid–liquid partitioning procedure prior to LC–MS/MS analysis. Evaluation of the method revealed good linearity, accuracy and precision. The limits of quantification varied from 0.1 to 1 μg/kg depending on the analyte and matrix. The average extraction and clean-up recoveries in different matrices were between 45 (only for ergometrine in biscuit) and 90%. The uncertainty associated with the analytical method was not higher than 51% and 30%, at concentration levels of 2.5 and 150 μg/kg respectively. Analyte epimerization proved to be minimal during the analytical procedure. The method has been successfully applied to the determination of ergot alkaloids in some Belgian food and feed commodities. Ergot alkaloids were found in 104 out of 122 samples investigated. Ergosine was the most frequently occurring alkaloid, while the highest levels were observed for ergotamine, ergocristine or ergosine, depending on the product type. The total alkaloid content in positive samples varied from 1 to 1145 μg/kg.     

Platinum particle size and support effects in NO(x) mediated carbon oxidation over platinum catalysts

Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces.