Non-heme Fe(IV)-oxo intermediates

High-valent non-heme iron-oxo intermediates have been proposed for decades as the key intermediates in numerous biological oxidation reactions. In the past three years, the first direct characterization of such intermediates has been provided by studies of several alphaKG-dependent oxygenases that catalyze either hydroxylation or halogenation of their substrates. In each case, the Fe(IV)-oxo intermediate is implicated in cleavage of the aliphatic C-H bond to initiate hydroxylation or halogenation. The observation of non-heme Fe(IV)-oxo intermediates and Fe(II)-containing product(s) complexes with almost identical spectroscopic parameters in the reactions of two distantly related alphaKG-dependent hydroxylases suggests that members of this subfamily follow a conserved mechanism for substrate hydroxylation. In contrast, for the alphaKG-dependent non-heme iron halogenase, CytC3, two distinct Fe(IV) complexes form and decay together, suggesting that they are in rapid equilibrium. The existence of two distinct conformers of the Fe site may be the key factor accounting for the divergence of the halogenase reaction from the more usual hydroxylation pathway after C-H bond cleavage. Distinct transformations catalyzed by other mononuclear non-heme enzymes are likely also to involve initial C-H bond cleavage by Fe(IV)-oxo complexes, followed by diverging reactivities of the resulting Fe(III)-hydroxo/substrate radical intermediates.     

丹麦Lynetten污水处理厂运行维护与管理

对丹麦第一大城市污水处理厂--Lynetten污水处理厂的运行、维护和日常管理进行了详细介绍.同时对该污水处理厂的能耗状况、污泥处理工艺以及污水和污泥处理费用进行了总结和分析.     

Energieeffizienz in der Vakuumtechnik

Energy efficiency in vacuum technology Vacuum is used to produce a huge variety of products of our everyday life. To provide the vacuum environment, a lot of energy is usually used and therefore the vacuum pumps should run as efficient as possible. Actually, many various improvements can be made to gain energy savings on vacuum pumps. With those considered in this paper it's possible to save 928 GWh/a of energy in the EU and thereof 629 GWh/a or 64 % are economically realizable. Only specific improvements concerning the vacuum system are taken into account, basic technology options, like motors, controls, etc., are excluded. To show and discuss the results a conserved energy supply curve is used.     

Neural networks as material models within a multiscale approach

This paper shows the application of neural networks in a multiscale analysis of a reinforced concrete beam. A mesoscale model is presented, which simulates the pullout test of a reinforcement bar in concrete. By applying a homogenization procedure, a macroscopic stress vs. crack opening response is obtained from the mesoscale simulations. The neural network is used to approximate this relation in a macroscale simulation and replaces the material formulation of the interface layer between concrete and reinforcement, thus avoiding the computationally expensive parallel simulation on different scales.     

Playing chess unconsciously.

Expertise in a certain stimulus domain enhances perceptual capabilities. In the present article, the authors investigate whether expertise improves perceptual processing to an extent that allows complex visual stimuli to bias behavior unconsciously. Expert chess players judged whether a target chess configuration entailed a checking configuration. These displays were preceded by masked prime configurations that either represented a checking or a nonchecking configuration. Chess experts, but not novice chess players, revealed a subliminal response priming effect, that is, faster responding when prime and target displays were congruent (both checking or both nonchecking) rather than incongruent. Priming generalized to displays that were not used as targets, ruling out simple repetition priming effects. Thus, chess experts were able to judge unconsciously presented chess configurations as checking or nonchecking. A 2nd experiment demonstrated that experts' priming does not occur for simpler but uncommon chess configurations. The authors conclude that long-term practice prompts the acquisition of visual memories of chess configurations with integrated form-location conjunctions. These perceptual chunks enable complex visual processing outside of conscious awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gait generation considering dynamics for artificial segmented worms

This paper deals with terrestrial worm-like locomotion systems living in a straight line. They are modeled as chains of mass points having ground interaction via spikes which make the velocities unidirectional. A method is presented to construct gaits with any desired time pattern of resting mass points (which are acted on by the propulsive forces). Taking the dynamics into consideration, conclusions about the choice and shift of gaits in connection with actuator data are given.     

Fire resistance of wood treated with a cationic silica sol

Wood was treated with the cationic silica sol (CSS) Levasil 200S and dried at various temperatures (room temperature, 40, 60, 80 and 103 °C). A water leaching test revealed fixation of the silica in wood even after drying at room temperature. Maximum cross sectional swelling of the specimens decreased from 15.6 % (untreated control) to 13.0 %, when treated wood was dried at 103 °C; cell wall bulking values were also negative (?2.3 %), indicating a thermal degradation of the cell wall polymers catalyzed by the CSS. Penetration of the CSS into the cell wall did not occur. A simple flammability test revealed increased fire resistance of the treated wood. Mass loss and velocity of mass loss as well as burning time were reduced; glowing of the formed charcoal was completely prevented. The effectiveness increased with increasing weight percent gain of the CSS in the wood. Thermo gravimetric analysis under nitrogen atmosphere displayed only minor reduction in the initial temperature of thermal decomposition for wood treated with CSS as compared to the control. In the presence of oxygen the resulting charcoal showed comparable thermal behaviour to the control. The yield of charcoal after pyrolysis was increased to a minor extent (from 19.9 to 23.0 %), indicating that the release of combustible gases was hardly reduced. The mode of action of enhanced fire resistance due to CSS-treatment is discussed.