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。     

Raptor wing morphing with flight speed

In gliding flight, birds morph their wings and tails to control their flight trajectory and speed. Using high-resolution videogrammetry, we reconstructed accurate and detailed three-dimensional geometries of gliding flights for three raptors (barn owl, Tyto alba; tawny owl, Strix aluco, and goshawk, Accipiter gentilis). Wing shapes were highly repeatable and shoulder actuation was a key component of reconfiguring the overall planform and controlling angle of attack. The three birds shared common spanwise patterns of wing twist, an inverse relationship between twist and peak camber, and held their wings depressed below their shoulder in an anhedral configuration. With increased speed, all three birds tended to reduce camber throughout the wing, and their wings bent in a saddle-shape pattern. A number of morphing features suggest that the coordinated movements of the wing and tail support efficient flight, and that the tail may act to modulate wing camber through indirect aeroelastic control.     

Relativistic red‐black trees

This paper presents algorithms for concurrently reading and modifying a red‐black tree (RBTree). The algorithms allow wait‐free, linearly scalable lookups in the presence of concurrent inserts and deletes. They have deterministic response times for a given tree size and uncontended read performance that is at least 60% faster than other known approaches. The techniques used to derive these algorithms arise from a concurrent programming methodology called relativistic programming. Relativistic programming introduces write‐side delay primitives that allow the writer to pay most of the cost of synchronization between readers and writers. Only minimal synchronization overhead is placed on readers. Relativistic programming avoids unnecessarily strict ordering of read and write operations while still providing the capability to enforce linearizability. This paper shows how relativistic programming can be used to build a concurrent RBTree with synchronization‐free readers and both lock‐based and transactional memory‐based writers. Copyright © 2013 John Wiley & Sons, Ltd.     

Energy and the Environment: EPA's New Carbon Rule: Lots of Heat,Little Light

Shakespeare seems to describe appropriately the Environmental Protection Agency's proposed new Clean Power Act rule, a 645-page monstrosity that will, supposedly, reduce carbon dioxide (CO₂) emissions from electric-generating plants by 30 percent from 2005 levels by 2030. Although power plant emissions have already decreased significantly since 2005, thanks to the wonders of hydraulic fracturing and low-cost natural gas, the EPA's rule nevertheless is supposed to save the world from the multitudinous horrors that will be wrought by global warming—climate change, climate volatility, or whatever today's favorite moniker happens to be.     

Outlook—Industry Standards: NAESB at the Forefront of Standards Development in 2014

As we enter our 20th year, you might ask, “How am I impacted by NAESB?” To understand our impact, we will provide a quick profile of our organization and describe the activities under way and those on the horizon.     

Bioreduction of uranium: environmental implications of a pentavalent intermediate

The release of uranium and other transuranics into the environment, and their subsequent mobility, are subjects of intense public concern. Uranium dominates the inventory of most medium- and low-level radioactive waste sites and under oxic conditions is highly mobile as U(VI), the soluble uranyl dioxocation (UO2)2+. Specialist anaerobic bacteria are, however, able to reduce U(VI)to insoluble U(IV), offering a strategy for the bioremediation of uranium-contaminated groundwater and a potential mechanism for the biodeposition of uranium ores. Despite the environmental importance of U(VI) bioreduction, there is little information on the mechanism of this transformation. In the course of this study we used X-ray absorption spectroscopy (XAS) to show that the subsurface metal-reducing bacterium Geobacter sulfurreducens reduces U(VI) by a one-electron reduction, forming an unstable (UO2)+ species. The final, insoluble U(IV) product could be formed either through further reduction of U(V) or through its disproportionation. When G. sulfurreducens was challenged with the chemically analogous (NpO2)+, which is stable with respect to disproportionation, it was not reduced, suggesting that it is disproportionation of U(V) which leads to the U(IV) product. This surprising discrimination between U and Np illustrates the need for mechanistic understanding and care in devising in situ bioremediation strategies for complex wastes containing other redox-active actinides, including plutonium.     

The utility of coal molecular models

There are a large number (> 125) of molecular representations for coals that span the rank range over seven decades. However, their utility has mostly been in representing chemical structural features, rather than in probing physical structure or exploring the structure-behavior relationship. This paper examines the utility of coal models and reviews the existing and emerging opportunities for coal models to contribute to coals effective utilization via demystification of the structure-behavior relationship. Coal models have been used to explore the coalification pathway, including contraction with water removal. Physical evaluations have probed the density of models as a check on their accuracy. Pore size distribution and sorption have been explored in simple pores and more recent work with carbon dioxide, water and methane sorption within the porous structure of large-scale (< 20,000 atoms) model. Pair distribution frequency and small angle X-ray scattering simulations have also been compared with experimental observations and offer an additional check on the constitution of the model structure. Simulated HRTEM and simulated (calculated) NMR spectra also exist. Models have been disassembled in efforts to represent the pyrolysis process, char formation, and char reactivity (including the role of ion-exchangable ions). Similar to the pyrolysis models, direct liquefaction has been explored with a pyrolysis style approach. Coal-solvent swelling, and coal-solvent solubility have also been explored. While considerable progress has accompanied improvements in computational power and software advances, it is the generation of the model that is the most significant barrier to the meaningful utility of these models. The ability to generate large-scale models (incorporation of molecular weight diversity and structural diversity) with new automation approaches, coupled with new dynamic force-fields that can simulate reactive events in complicated materials like coals, offers a new hope for the utility of coal or char molecular models to probe our understanding and aid in the scientific method rather than our current informed trial and error approach.     

Characteristics and Catalytic Properties of Mesocellular Foam Silica Supported Pd Nanoparticles in the Liquid-Phase Selective Hydrogenation of Phenylacetylene

Abstract  

An ultra-large pore mesocellular foam silica (MCF) was employed as a support for preparation of supported Pd catalysts for the liquid-phase selective hydrogenation of phenylacetylene. The catalysts were prepared by three different routes: (i) incipient wetness impregnation using Pd(II)acetate solution (Pd/MCF-imp), (ii) impregnation of colloidal Pd nanoparticles obtained by the solvent reduction method (Pd/MCF-col), and (iii) in situ synthesis of MCF in the presence of the Pd colloid (Pd/MCF-ss). The conventional impregnation method resulted in more agglomeration of Pd particles and partial collapse of MCF structure, hence the Pd/MCF-imp exhibited the lowest selectivity towards styrene at total conversion of phenylacetylene. Only the Pd/MCF-ss, in which most of the Pd nanoparticles were encapsulated by the silica matrix, was found to retain high styrene selectivity (>80%) after complete conversion of phenylacetylene. Comparing to the other highly efficient Pd catalysts reported in the literature under similar reaction conditions, it can be emphasized that coverage of Pd surface by the support produces great beneficial effect for enhancing styrene selectivity, regardless of the type of supports used (i.e., TiO₂, carbon nanotubes, or mesostructured silica).