Models for organics removal from vinasse from ethanol production

Global ethanol production generates almost 100 billion liters per year of a high-strength liquid waste called vinasse. One sustainable method of treating vinasse using environmental biotechnology is anaerobic digestion, which generates biogas that can be used as a renewable energy resource. Although a number of models have been developed for predicting biogas generation rates, no previous study has modeled liquid organic removal rates for vinasse treatment. The goal of this research was thus to develop models for predicting liquid-phase organic removal rates for anaerobic treatment of vinasse. 6-L laboratory-scale batch reactors were filled with vinasse of six different compositions and operated at three different mesophilic temperatures (30, 35, 40 °C). Biochemical and chemical oxygen demand (BOD and COD) were measured over time using Standard Methods 5210B and 5220C. Based on data collected, multiple linear regression equations (R² = 0.79 and 0.94) were developed to predict first-order rate constants k_BOD and k_COD as functions of temperature and vinasse composition (initial values of nitrogen, potassium, phosphorous, and sulfur). The first-order models developed require a small number of readily available input parameters. They apply to treatment of vinasse from ethanol produced from corn and milo; future work can test their applicability to ethanol produced from other feedstocks. The models can be used for sizing/design of reactors for anaerobic treatment of vinasse.     

Electroluminescence from silicon nanoparticles fabricated from the gas phase

Electroluminescence from as-prepared silicon nanoparticles, fabricated by gas phase synthesis, is demonstrated. The particles are embedded between an n-doped GaAs substrate and a semitransparent indium tin oxide top electrode. The total electroluminescence intensity of the Si nanoparticles is more than a factor of three higher than the corresponding signal from the epitaxial III-V semiconductor. This, together with the low threshold voltage for electroluminescence, shows the good optical properties of these untreated particles and the efficient electrical injection into the device. Impact ionization by electrons emitted from the top electrode is identified as the origin of the electrically driven light emission.     

Enhanced photoluminescence from polycrystalline ZnO films resulting from oxygen processing

We report studies of photoluminescence from polycrystalline ZnO films deposited on sapphire as a function of the in situ oxygen pressure during growth and ex situ annealing. The ultraviolet photoluminescence was observed to increase by more than two orders of magnitude as a result of the annealing treatment. Enhanced cathodoluminescence was observed from the same films. The role of oxygen defects is discussed.     

Lessons from Vitruvius

Vitruvius's Ten Books on Architecture was in regular use as a design manual for over 1500 years. This paper argues for a reinterpretation of Vitruvius in terms of design method. On this view, the study of Vitruvius and his historical influence still has important lessons for the theory of types and for the construction of design heuristics.     

Message from guest

正今年3月在伦敦签署的新中英合作协议和去年12月在北京签署的中英标准互认专项协议标志着中英合作掀开了新的篇章!自2004年首次签署合作协议以来,BSI和SAC已经携手走过了整整十年。让我们共同努力,着眼全球,充分发挥标准的积极作用,支撑经济发展,保护消费者,帮助政府实现全面增长和社会繁荣。     

Letter from Editors-in-Chief

<正>Engineering comes to you at last.As the Editors-in-Chief of Engineering,first of all,we wish to thank all the scholars at home and abroad for their eager responses and full support,and all those who have provided encouragement and contributions toward the emergence of this journal.     

Learning from experience

Some process accidents and the actions needed to prevent them occurring again are described. They illustrate the following points: Some investigators are too eager to recommend changes in instructions or better observation of them than to look for ways of removing hazards or for changes in design that will make an accident less likely. Some people fail to calculate the effects of changes or the time required for them to take place. Facts that are well known in one industry or company may be unknown in another. The incidents have been chosen because of their value as learning experiences.     

编读直通车

‘读过《中国质量与品牌》创刊号,觉得这本杂志的权威性很高,主打文章“神五”系列报道角度很新,是我在其他杂志上未看到的。我很喜欢杂志的编排,比较大气,图片也很精彩。但我也提点个人的意见,有些文章还可以再挖得深一些,记者可以深入实践去获得更多的信息。另外, 杂志的新闻性可以更强一点,和现实联系再紧密一点。希望《中国质量与品牌》更上一层楼! ——山西读者刘敏‘看了贵刊的创刊号,使我兴奋不已, 文章大都很精彩。对徐匡迪的采访,他既是政府官员,又是著名的学者,论述很深     

Photographs from Auschwitz

Abstract

Photographs, albums, families. Many psychotherapists ask their patients to bring in their family albums to discover a new, sharper point of view of the family, its structure and dependencies. Many times we ask friends to show us their family photo album to get to know them better. Sometimes we ourselves look at our own family photo album and all of a sudden we see details we have not yet noticed: a smile, a look, a sign.     

X-rays from stars

More than two years of observation with Chandra and XMM-Newton has provided a rich harvest of new results on the physics of stellar coronae and winds. High-resolution X-ray spectroscopy in particular has opened new windows to the structure, the dynamics and the composition of stellar atmospheres. The present paper presents selected results from the areas of hot and cool stars and star formation, summarizing new views of the thermal structure and energy release in stellar coronae, observations of magnetically active brown dwarfs, the structure of winds in hot stars, the physics in colliding-wind binary systems, and X-rays from protostars and stellar jets.