Fast lateral hydrogen diffusion in magnesium-hydride films on sapphire substrates studied by electrochemical hydrogenography

Hydrogen diffusion in thin magnesium films in lateral film direction is studied by stepwise electrochemical loading via the change in optical light transmission (‘electrochemical hydrogenography’) during the dihydride formation. During the first loading step, the dihydride front propagation kinetics allows determining the lateral hydrogen diffusion coefficient in the film, by applying an analytical model and, alternatively, by comparison with finite-element simulations. Subsequent loading steps show a time lag behavior in the dihydride front propagation. Therefore, they can be regarded as permeation experiments. These subsequent loading steps can be explained by hydrogen diffusion along grain boundaries and by taking the Gaussian shape of the hydrogen site energy distribution in the grain boundaries into account. In average, an effective hydrogen diffusion coefficient of $3_{?2}^{+12}?{10}^{?12}\raisebox{1ex}{${\text{m}}^2$}\!\left/ \!\raisebox{-1ex}{$\text{s}$}\right.$ was found in lateral film direction. This value is the highest value known for hydrogen diffusion in Mg-dihydride, at room temperature. Possible sources for this high lateral hydrogen diffusivity are discussed including preferential hydrogen diffusion along the Mg/Mg-oxide interface, anisotropy of diffusion coefficients and lowering of diffusion energy barrier upon anisotropic film expansion.     

Effect of dimorphic regulation on heterologous glucose oxidase production by Mucor circinelloides

The production of Aspergillus niger glucose oxidase (GOX) and native amylase by the recombinant M. circinelloides KFA199 strain under conditions of dimorphic growth was investigated. The recombinant KFA199 strain was compared to its parental ATCC 1216b strain and a wild‐type CBS 232.29 strain under similar morphology‐controlled conditions. Cultivation in Vogel's medium supplemented with ergosterol/Tween‐80 and sparged with nitrogen gas was most suitable for yeast‐like biomass production under anaerobic conditions. Anaerobic growth was characterized by high levels of ethanol formation and linear growth rates of 0.24–0.05/h, indicating metabolic stress. Subsequent to anaerobic growth, cultures were shifted to aerobic conditions to induce aerobic mycelial growth. GOX produced by the recombinant KFA199 after the shift to aerobic conditions was poorly secreted and accumulated intracellularly to 0.56 U/ml_culture. Amylase production by the KFA199, ATCC12b and CBS 232.29 strains was determined during growth on starch after the shift to aerobic culture. Growth‐associated amylase production by the ATCC 1216b (0.63 U/ml_culture) and wild‐type CBS 232.29 (0.33 U/ml_culture) strains was substantially higher than by the recombinant KFA199 strain (0.07 U/ml_culture), which may be related to the leucine auxotrophy of the transformation host, or genetic changes induced during transformation of the KFA199 strain. Copyright © 2010 John Wiley & Sons, Ltd.     

No improvement in fruit quality through chemical flower thinning in sweet cherry (Prunus avium L.)

BACKGROUND: Chemical flower thinning with ammonium thiosulfate (ATS) was applied on branches of sweet cherry (Prunus avium L.) cultivars ‘Blaze Star’, ‘Samba’, ‘Techlovan’ and ‘Merchant’ (all grafted on GiSelA 5) in a two‐year field study in 2006 and 2007. Different concentrations of ATS (8.82 and 17.64 g L^?1) and different application times were studied. Fruit quality parameters analysed included crop load, fruit size, fruit weight, flesh/stone ratio, content of soluble solids, pH value and content of titratable acids. RESULTS: Crop load was significantly affected (P < 0.01) by application, cultivar and year. Fruit size, fruit weight and content of titratable acids were not improved by any of the application strategies. An influence of cultivar and application on pH value was observed (P < 0.05). Flesh/stone ratio was significantly enhanced (P < 0.05) in ‘Blaze Star’ only, while content of soluble solids was significantly affected in ‘Techlovan’ only in 2007. CONCLUSION: No general improvement in quality parameters was achieved by chemical flower thinning in the P. avium cultivars studied over a two‐year field experiment. Copyright © 2009 Society of Chemical Industry     

Hydrogen production from carrot pulp by the extreme thermophiles Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana

Hydrogen was produced from carrot pulp hydrolysate, untreated carrot pulp and (mixtures of) glucose and fructose by the extreme thermophiles Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana in pH-controlled bioreactors. Carrot pulp hydrolysate was obtained after enzymatic hydrolysis of the polysaccharide fraction in carrot pulp. The main sugars in the hydrolysate were glucose, fructose, and sucrose.     

A review of occupant control on natural ventilation

According to IPCC (Intergovernmental Panel on Climate Change), the largest use of energy in commercial buildings is space heating in colder climates and air conditioning in hot climates. In Europe, the Directive on the energy performance of buildings EPBD (European Energy Performance of Buildings Directive) [1] provides a framework for national building performance regulations and calculation procedures. However, there are often large discrepancies between calculated and measured energy performance of buildings. One main reason is the behaviour of occupants, which is often not reflected in calculation models.This paper presents a literature review of various parameters influencing the effectiveness of occupant controlled natural ventilation. Additionally possibilities to implement these influences into calculation procedures/building simulation and adaptive thermal comfort evaluation are discussed.     

Offshore wind farm wake recovery: Airborne measurements and its representation in engineering models

We present an analysis of wind measurements from a series of airborne campaigns conducted to sample the wakes from two North Sea wind farm clusters, with the aim of determining the dependence of the downstream wind speed recovery on the atmospheric stability. The consequences of the stability dependence of wake length on the expected annual energy yield of wind farms in the North Sea are assessed by an engineering model. Wakes are found to extend for significantly longer downstream distances (>50 km) in stable conditions than in neutral and unstable conditions (  15 km). The parameters of one common engineering model are modified to reproduce the observed wake decay at downstream distances  30 km. More significant effects on the energy yield are expected for wind farms separated by distances  30 km, which is generally the case in the North Sea, but additional data would be required to validate the suggested parameter modifications within the engineering model. A case study is accordingly performed to show reductions in the farm efficiency downstream of a wind farm. These results emphasize not only the importance of understanding the impact of atmospheric stability on offshore wind farms but also the need to update the representation of wakes in current industry models to properly include wake‐induced energy losses, especially in large offshore clusters.     

Separation and characterization of cis-trans isomers of α-tocotrienol by HPLC using a permethylated β-cyclodextrin phase

 The behaviour of α-, β-, γ- and δ-tocotrienols (structurally related to tocopherols with naturally trans-configurated double bonds in the side-chain) during HPLC on a permethylated β-cyclodextrin phase was studied. A newly developed isocratic HPLC method is described with an acetonitrile/water (58:42 by vol.) eluent and fluorescence detection at an emission wavelength of 330 nm (excitation wavelength = 295 nm). Each of the separately injected tocotrienols exhibited four peaks. The four separated components of α-tocotrienol were identified by spectroscopy (MS, ¹H-NMR, FTIR) to be structural side-chain isomers. The order of retention times was determined to be all-cis-α-tocotrienol followed by cis-trans-/trans-cis-α-tocotrienol (differentiation between the two compounds was not possible) with all-trans-α-tocotrienol as the last eluting isomer. Received: 27 June 1997     

五富兰克林大楼

该大楼有20层,包含55个公寓,在楼中可以眺望啥德逊河、东河和曼哈顿的天际线。 该大楼有一个戏剧性、极富装饰性的立面,灵感来自Tribeca的19世纪的铸铁建筑和当代时尚。闪闪发光的黑色金属横带将包装的墙面扭曲,划分了阳台、平台和遮阳篷的位置,同时体现了立面的框架感。     

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Speckle contrast of the sum of N partially correlated speckle patterns

In this paper a general method is presented for calculating the theoretical speckle contrast of a sum of correlated speckle patterns, motivated by the need to suppress the presence of speckle in laser projection displays. The method is applied to a specific example, where correlated speckle patterns are created by sequentially passing light through partially overlapping areas on a diffuser, before being projected onto a screen. This design makes it possible to find a simple expression for the correlation between speckle patterns. When the set of correlations involves symmetry, it is shown that the expression for the speckle contrast becomes simpler. The difference in performance between discretely and continuously varying speckle patterns is also investigated. In an example with speckle reduction by a rotating sinusoidal grating, it is found that continuous variation gives a speckle contrast that is 0.61 times the contrast obtained by discretely summing the maximum number of independent patterns.