Volatile flavour components of baked potato flesh. A comparison of eleven potato cultivars.

Tubers of eleven cultivars of potato were baked and the flavour compounds from the flesh were isolated by headspace adsorption onto Tenax and analysed by gas chromatography-mass spectrometry (GC-MS). Lipid degradation and the Maillard reaction were the main sources of flavour compounds, accounting for 22-69% and 28-77%, respectively, of the total yields. Various sulfur compounds, methoxypyrazines and terpenes were also identified at lower levels. Relative aroma impact values (RAVs) were calculated by dividing compound yields by the odour threshold value. Compounds contributing most to aroma (RAV > 10,000 in at least one cultivar) were 2-isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, beta-damascenone, dimethyl trisulfide, decanal and 3-methylbutanal. The observed differences in yields and RAVs for compounds among cultivars would be expected to result in differences in perceived flavour.     

Stochastic texture image estimators for local spatial anisotropyand its variability

A new image analysis technique is proposed for the evaluation of local anisotropy and its variability in stochastic texture images. It utilizes the gradient function to provide information on local anisotropy, from two-dimensional (2-D) density images for foil materials like polymer sheets, nonwoven textiles, and paper. Such images can be captured by radiography or light-transmission; results are reported for a range of paper structures, and show that the proposed technique is more robust to unfavorable imaging conditions than other approaches. The method has potential for on-line application to monitoring and control of anisotropy and its variability, as well as local density itself, in continuous manufacturing processes     

Hydrodynamic study of a toroidal fluidized bed reactor

Hydrodynamic behavior of a newly developed toroidal fluidized bed reactor is studied in this work. The reactor has a gas distributor consisting of angled blades in an annular ring at the reactor bottom. The driving force for particles to move over the distributing blades comes from the velocity head of gas jets accelerated upon entering the blade spacing. Relevant hydrodynamic behaviors are measured with various inert materials in a pilot scale 400-mm toroidal fluidized bed reactor. The observed hydrodynamic behavior is found to be essentially predictable at ambient temperature by conventional hydrodynamic models. Fine particle tracking on the reactor wall is clearly observed through oxidation of zinc dross at a bed temperature of around 1120°C, and is simulated on the basis of a simplified mathematical model. Hydrodynamic issues, such as particle flying trajectory and retention time in the reactor, are discussed based on the developed model.     

An energy evaluation of coupling nutrient removal from wastewater with algal biomass production

Recently, several life cycle analyses of algal biodiesel from virtual production facilities have outlined the potential environmental benefits and energetic balance of the process. There are a wide range of assumptions that have been utilized for these calculations, including the addition of fertilizers and carbon dioxide to achieve high algal yields in open ponds. This paper presents an energy balance of microalgal production in open ponds coupled with nutrient removal from wastewater. Actual microalgal yields and nutrient removal rates were obtained from four pilot-scale reactors (2500 gallons each) fed with wastewater effluent from a conventional activated sludge process for 6 months, and the data was used to estimate an energy balance for treating the total average 12 million gallons per day processed by the wastewater treatment plant. Since one of the most energy-intensive steps is the dewatering of algal cultures, several thickening and dewatering processes were compared. This analysis also includes the energy offset from removing nutrients with algal reactors rather than the biological nutrient removal processes typically utilized in municipal wastewater treatment. The results show that biofuel production is energetically favorable for open pond reactors utilizing wastewater as a nutrient source, even without an energy credit for nutrient removal. The energy content of algal biomass was also considered as an alternate to lipid extraction and biodiesel production. Direct combustion of algal biomass may be a more viable energy source than biofuel production, especially when the lipid content of dry biomass (10% in this field experiment) is lower than the high values reported in lab-scale reactors (50–60%).     

Effect of material properties and processing conditions on the prediction accuracy of a CFD model for simulating high pressure thermal (HPT) processing

High pressure thermal (HPT) processing is a candidate technology for achieving commercial sterility of low acid shelf-stable and chilled food products. A major food safety challenge to the implementation of HPT lies in achieving temperature uniformity inside the vessel during processing. Computational Fluid Dynamics (CFD) modelling can be used to predict locally specified temperature profiles arising during HPT processing, but it is essential that such models are validated, and that predictions agree well with temperatures measured in actual processes. In this work, the effects of variations in inputs for compression fluid properties and process conditions (i.e., the applied pressure profiles) on the prediction accuracy of a CFD model for a Stansted 3.6 L Isolab HPTS system were studied. Good agreement was found between simulated and measured temperature distributions when accurate compression heating coefficients for the compressed materials and actual pressure profiles were used as inputs of the model. Inaccurate approximations of these values and conditions resulted in much less useful models, highlighting the importance of attention to detail in input data for CFD models of HPT processing, in these still early stages of development of the technology.     

Office workers' computer use patterns are associated with workplace stressors

This field study examined associations between workplace stressors and office workers' computer use patterns. We collected keyboard and mouse activities of 93 office workers (68F, 25M) for approximately two work weeks. Linear regression analyses examined the associations between self-reported effort, reward, overcommitment, and perceived stress and software-recorded computer use duration, number of short and long computer breaks, and pace of input device usage. Daily duration of computer use was, on average, 30 min longer for workers with high compared to low levels of overcommitment and perceived stress. The number of short computer breaks (30 s–5 min long) was approximately 20% lower for those with high compared to low effort and for those with low compared to high reward. These outcomes support the hypothesis that office workers' computer use patterns vary across individuals with different levels of workplace stressors.     

台北艺术中心

正为什么过去百年间最令人兴奋的剧场盛事总是发生在正规场所之外?建筑如何才能超越自身卑微的命运,摆脱那种限制各种可能的宿命?近年来,世界各地的演艺中心数目渐增,但不知何故,这些演艺中心似乎达成一种共识,呈现出雷同的空间组合:一座约2 000席的大型演艺厅和一个1 500席的中型剧院,再加上一个黑盒子剧场。标志性的外形掩饰以典型19世纪做法为基础的     

Understanding Bulk Defects in Topological Insulators from Nuclear‐Spin Interactions

Non‐invasive local probes are needed to characterize bulk defects in binary and ternary chalcogenides. These defects contribute to the non‐ideal behavior of topological insulators. The bulk electronic properties are studied via ¹²⁵Te NMR in Bi₂Te₃, Sb₂Te₃, Bi_0.5Sb_1.5Te₃, Bi₂Te₂Se, and Bi₂Te₂S. A distribution of defects gives rise to asymmetry in the powder lineshapes. The Knight shift, line shape, and spin‐lattice relaxation are investigated in terms of how they affect carrier density, spin‐orbit coupling, and phase separation in the bulk. The present study confirms that the ordered ternary compound Bi₂Te₂Se is the best topological insulator candidate material at the present time. These results, which are in good agreement with transport and angle‐resolved photoemission spectroscopy studies, help establish the NMR probe as a valuable method to characterize the bulk properties of these materials.