移动的芝加哥

说到芝加哥印象，我想除了公牛队应该就是穿梭在城市里那套陈旧破烂的高架列车系统了，美国的大多数“古董”车辆都集中于此，来来往往发出巨大的声响。每天往返于洛根广场和克拉克湖，我早已习惯蓝线上车辆的一切，这是1969年阿波罗登月时制造的，老式的四页折叠门，座椅横置，车厢与车厢之间并不连通，但我喜欢这样古老的味道。     

EL7564C的双电压FPGA电源解决方案

概述Xilinx公司的FPGA(现场可编程门阵列)芯片正向高密度化发展,FPGA的内核在提供低成本和高性能的同时还要求低功耗.当今先进的亚微米IC工艺正趋于采用低电压供电,同时这将导致对大电流的不断需求.工程线路板的设计必需满足这类电源供电的需要.     

土耳其陶瓷行业概览

土耳其陶瓷行业，于上世纪50年代开始以工业概念投入生产。自80年代以来，稳操迅速发展步伐。90年代开始更引进最先进技术实现了设备现代化。陶瓷行业是大工业一个分支，主要由以下子行业构成，主要为建筑业提供了配套。     

Health effects engineering of coal and biomass combustion particulates: influence of zinc, sulfur and process changes on potential lung injury from inhaled ash

This paper is concerned with health effects of the ash aerosol formed from the co-combustion of municipal sewage sludge (a CO₂ neutral, ostensibly ‘green’ biomass fuel) with pulverized coal. To study, and mitigate, possible lung injury caused by inhalation of these ash particles, it is useful to employ ‘Health Effects Engineering’, which involves collaboration between combustion researchers and toxicologists. Health Effects Engineering attempts to build connections between mechanisms that form particulates during the combustion process and mechanisms that cause these ill health effects. By employing the methods of Health Effects Engineering, one can determine not only which fuel attributes are likely to contribute to lung injury, but also how tendencies of the ash to cause lung injury can be engineered out of the combustion process.Initial results showed that inhalation of ash from the co-combustion of municipal sewage sludge (MSS) and pulverized coal caused much greater lung damage in mice, as measured by lung permeability increase, than that of coal ash, or MSS ash, alone. MSS contains substantial quantities of zinc but little sulfur, while coal contains sulfur but little zinc. Therefore, systematic experiments were conducted to determine the health effects of combustion generated zinc particles and zinc plus sulfur particles. Zinc without sulfur led to ‘normal’ behavior as far as lung permeability was concerned. Zinc with sulfur added led to the ‘abnormal’ behavior noted also in the coal+MSS experiments. Therefore, the bad actor was identified to be zinc together with sulfur, and that was why the co-combustion of coal and MSS caused greater lung injury than the combustion of either fuel alone. Health effects engineering can also be employed to diminish this health risk caused by burning fuels containing both zinc and sulfur. Injection of a kaolinite sorbent downstream of the flame, but above the Zn dew point, can sequester the Zn, and react it to form a new species which was shown to be relatively benign.     

Effects of α-, β- and maltosyl-β-cyclodextrins use on the glucoraphanin–sulforaphane system of broccoli juice

Cyclodextrins (CDs) are macromolecules with several industrial applications, being particularly used in the food industry as health-promoting compounds protection agents, as flavour stabilizers, or to eliminate undesired tastes and browning reactions, among others. This study shows the effects of α- (10, 30 and 40 mmol L⁻¹), β- (3, 6 and 10 mmol L⁻¹) and maltosyl-β-CDs (30, 60 and 90 mmol L⁻¹) use on the health-promoting glucoraphanin–sulforaphane system of a broccoli juice up to 24 h at 22 °C. Maltosyl-β-CD (90 mmol L⁻¹) highly retained glucoraphanin content after 24 h at 22 °C, showing better effectiveness than β-CD (10 mmol L⁻¹). Sulforaphane was efficiently encapsulated with β-CD at just 3 mmol L⁻¹, and the sulforaphane formed was stable during 3 h at 22 °C. On the other hand, 40 mmol L⁻¹ α-CD retained a high glucoraphanin content in broccoli juice. In contrast, glucoraphanin levels in juice without CDs decreased by 71% after 24 h. Consequently, CDs addition may potentially preserve glucoraphanin in this broccoli juice during industrial processing with the possibility to be later transformed by endogenous myrosinase after ingestion to the health-promoting sulforaphane. © 2018 Society of Chemical Industry     

Effect of Pulsed Light Treatment on the Germination of Bacillus subtilis Spores

Food and Bioprocess Technology - The loss of cell culturability (spore counts), spore germination and subsequent vegetative growth of Bacillus subtilis were evaluated after pulsed light (PL)...     

Design Optimization of a Portable Thermophoretic Precipitator Nanoparticle Sampler

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are developing methods for characterizing diesel particulate matter in mines. Introduction of novel engine and exhaust aftertreatment technologies in underground mines is changing the nature of diesel emissions, and metrics alternative to the traditional mass-based measurements are being investigated with respect to their ability to capture changes in the properties of diesel aerosols. The emphasis is given to metrics based on measurement of number and surface area concentrations, but analysis of collected particles using electron microscopy (EM) is also employed for detailed particle characterization. To collect samples for EM analysis at remote workplaces, including mining and manufacturing facilities, NIOSH is developing portable particle samplers capable of collecting airborne nano-scale particles. This paper describes the design, construction, and testing of a prototype thermophoretic precipitator (TP) particle sampler optimized for collection of particles in the size range of 1–300 nm. The device comprises heated and cooled metal plates separated by a 0.8 mm channel through which aerosol is drawn by a pump. It weighs about 2 kg, has a total footprint of 27 × 22 cm, and the collection plate size is approximately 4 × 8 cm. Low power consumption and enhanced portability were achieved by using moderate flow rates (50–150 cm³/min) and temperature gradients (10–50 K/mm with ΔT between 8 K and 40 K). The collection efficiency of the prototype, measured with a condensation particle counter using laboratory-generated polydisperse submicrometer NaCl aerosols, ranged from 14–99%, depending on temperature gradient and flow rate. Analysis of transmission electron microscopy images of samples collected with the TP confirmed that the size distributions of collected particles determined using EM are in good agreement with those determined using a Fast Mobility Particle Sizer.

Copyright 2012 American Association for Aerosol Research     

Distribution of degradative enzymatic activities in the mesocarp of two melon groups

The differences in polyphenol oxidase, peroxidase, pectin methylesterase and polygalacturonase activities as well as the main physical and chemical attributes of nine different slice portions (from the inner to the outer end and from the blossom to the stem end) of two groups of melon (Cucumis melo var. cantalupensis‘Galia’ cv. and inodorus‘Piel de sapo’ cv.) at commercial maturity were studied. Moving from the inner to the outer end of the pulp, physico‐chemical properties, such as pH, total soluble solids and phenolics increased whereas titratable acidity, firmness and Chroma decreased in both types, reflecting different degrees of maturity within the same fruit. As for physico‐chemical attributes, the enzymatic activities responsible for browning and softening phenomena showed an increasing trend moving from the inner to the outer end of mesocarp in both cv., except for polygalacturonase in cantalupensis type.     

走进迪拜塔

<正>世界最高建筑的噱头让无数人燃起了对迪拜的向往。那里曾经是一个石油大都,而今更是一个奢华艺术品交易的集散地。迪拜,像其他中东地区一样因石油而富庶,鳞次栉比的摩天大楼在霍尔河畔高高耸立。它有世界上最高的建筑,有世界上最大的购物中心,还有世界上首个七星级酒店……所有这些使迪拜充满了"超现实"的意味。当代艺术,在这里当然也同样超现实地蓬勃发展。     

Study of colloidal quantum-dot surfaces using an innovative thin-film positron 2D-ACAR method

Nanosized inorganic particles are of great interest because their electronic properties can be easily tailored, providing a tremendous potential for applications in optoelectronic devices, light-emitting diodes, solar cells and hydrogen storage. Confinement of electrons and holes to dimensions comparable to their wavelength leads to quantum-well states with modified wavefunctions and density of states. Surface phenomena are crucial in determining nanoparticle properties in view of their large surface-to-volume ratio. Despite a wealth of information, many fundamental questions about the nature of the surface and its relationship with the electronic structure remain unsolved. Ab initio calculations on CdSe nanocrystals suggest that passivating the ligands does not produce the ideal wurtzite structure and that Se atoms relax outwards irrespective of passivation. Here we show that implanted positrons are trapped at the surface of CdSe nanocrystals. They annihilate mostly with the Se electrons, monitor changes in composition and structure of the surface while hardly sensing the ligand molecules, and we thus unambiguously confirm the predicted strong surface relaxation.