Multi-level Modeling of Silica–Template Interactions During Initial Stages of Zeolite Synthesis

Zeolite synthesis is driven by structure-directing agents, such as tetrapropyl ammonium ions (TPA⁺) for Silicalite-1 and ZSM-5. However, the guiding role of these organic templates in the complex assembly to highly ordered frameworks remains unclear, limiting the prospects for advanced material synthesis. In this work, both static ab initio and dynamic classical modeling techniques are employed to provide insight into the interactions between TPA⁺ and Silicalite-1 precursors. We find that as soon as the typical straight 10-ring channel of Silicalite-1 or ZSM-5 is formed from smaller oligomers, the TPA⁺ template is partially squeezed out of the resulting cavity. Partial retention of the template in the cavity is, however, indispensable to prevent collapse of the channel and subsequent hydrolysis.

In-Situ,On-Demand Lubrication System for Space Mechanisms

Many of today's spaceraft have long mission lifetimes. Whatever the lubrication method selected, the initial lubricant charge is required to last the entire mission. Fluid lubricant losses are mainly due to evaporation, tribo-degradation, and oil creep out of the tribological regions.

In the past, several techniques were developed to maintain the appropriate amount of oil in the system. They were based on oil reservoirs (cartridges, impregnated porous parts), barrier films, and labyrinth seals. Nevertheless, all these systems have had limited success or have not established a proven record for space missions.

The system reported here provides to the ball-race contact fresh lubricant in-situ and on demand when the ball bearing is close to failure. The lubricant is stored in a porous cartridge attached to the inner or the outer ring of a ball bearing. The oil is released by heating the cartridge to eject oil, taking advantage of the greater thermal expansion of the oil compared to the porous network. The heating may be activated by torque increases that signal the depletion of oil in the contact. The low surface tension of the oil compared to the ball bearing material is utilized and the close proximity of the cartridge to the moving balls allows the lubricant to reach the ball-race contacts. This oil re-supply system avoided a mechanism failure, reduced torque to an acceptable level, and extended the life of the component.     

Real-time 3D thermal modeling of a magnetically levitated planar actuator

A transient thermal model used to monitor the temperature distribution in real-time in a long-stroke moving-magnet planar actuator is presented. The temperature distribution in the stator coils of the planar actuator depends on the trajectory of the levitated magnet plate as the set of active coils changes with the position of the translator. Using the presented real-time model, the transient thermal behavior can be investigated. Using this thermal model, the commutation algorithm of the planar actuator is adjusted to actively limit the temperature of the coils, and better spread the temperature over the stator coils.     

ANTIBACTERIAL EFFECT, HISTOLOGICAL IMPACT AND OXIDATIVE STRESS STUDIES FROM LAURUS NOBILIS EXTRACT

Laurus nobilis is one of the most broadly used spices in Moroccan gastronomy. Its antimicrobial activity against both gram-positive and gram-negative bacterial species was demonstrated. Likewise, its toxicity was investigated on Swiss albinos' mice . Daily, mice were treated orally with 0.003 and 0.3 mg during 7 days. Plasmatic markers and enzymatic systems were assessed and histological alterations were evaluated. A significant increase in creatine phosphokinase level was observed. The microscopic evaluation showed that L. nobilis induces morphological perturbation in mice's liver. The results also showed an inhibitory effect of glyceraldehydes 3-phosphate dehydrogenase and an important increase in the level of thiobarbituric acid reactive substances and succinate dehydrogenase and no change in catalase activities. The results showed that L. nobilis induces toxicity at 0.3 mg/g mouse and affects energy metabolism and oxidative stress.

PRACTICAL APPLICATIONS

The aim of the present study is to determine the antimicrobial effect of Laurus nobilis on pathogens for potential application as herbal medicine in infusion or oral preparation. The effect of the spice extract was investigated on the metabolic markers, stress biomarkers and clinical parameters. This study was completed with histological coupes. To our knowledge, this is the first report to demonstrate the laurel effect on energy metabolism and oxidative stress.     

Computation of finite and infinite zeros of linear multivariable systems: a state space approach

An iterative algorithm, developed by the authors to compute the finite zeros of a linear multivariable system (Sebakhy et al. 1983), is extended to compute the infinite zeros of the system as well. The method is simple, efficient and suitable for programming on a digital computer     

The deformation of the moving magnet plate of a commutated magnetically levitated planar actuator

This paper presents a method to calculate the deformation of the magnet plate of a commutated magnetically levitated planar actuator using a linked electromagnetic–mechanical model. The force and torque distribution on the moving magnet array is obtained from an electromagnetic model based on the surface charge method and the Lorentz force and torque integral. The mechanical model is a state-space model derived from FEM. This mechanical model uses the force and torque distribution to determine the deformation of the magnet plate during movement due to the commutated coil set.     

Stabilization of controlled positive discrete‐time T‐S fuzzy systems by state feedback control

This paper deals with sufficient conditions of asymptotic stability and stabilization for nonlinear discrete‐time systems represented by a Takagi–Sugeno‐type fuzzy model whose state variables take only nonnegative values at all times t for any nonnegative initial state. This class of systems is called positive systems. The conditions of stabilizability are obtained with state feedback control. This work is based on multiple Lyapunov functions. The results are presented in linear matrix inequalities form. A real plant is studied to illustrate this technique. Copyright © 2010 John Wiley & Sons, Ltd.     

Eating behavior in response to food-cue exposure: Examining the cue-reactivity and counteractive-control models.

Many studies have demonstrated that those high in weight-related concerns eat more after food-cue exposure, which is consistent with predictions of the cue-reactivity model. However, the counteractive-control model predicts that exposure to fattening foods activates dieting-related goals and behavior in weight-concerned individuals. Although these models seem incongruous, the authors hypothesized that the salience of the cue could represent a critical factor in determining which model is activated. The authors predicted that attending to salient food cues would result in increased intake (cue reactivity) in individuals with high weight-related concerns, whereas incidental food-cue exposure would result in decreased intake (counteractive control), relative to control exposure. The authors employed a 3 (attended vs. incidental vs. control cue) × 2 (low vs. high weight-related concerns) design. As expected, participants with high weight-related concerns who attended to a food cue ate more than did both those with high weight-related concerns in the control condition and those with low weight-related concerns in the attended-cue condition; however, intake of individuals with high weight-related concerns who were exposed to the incidental cue did not differ from that of those in the control condition. The manner of food-cue presentation may be a critical factor in determining eating behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impact of diesel policy banning on PM levels in urban areas

Increased use of diesel engine in on‐road vehicles presents a serious health concern, particularly in traffic‐congested urban areas. Diesel exhaust contains various gaseous and particulate pollutants, which, at high concentrations, pose adverse health effects. In this respect, various policy measures are being adopted worldwide to curtail emissions from diesel engines. This paper presents an assessment of diesel engine policy banning in the Greater Beirut Area. For this purpose, particulate matter levels in the air were measured after the ban and compared with concentrations reported prior to the ban. Health‐based socio‐economic benefits associated with improvement in air quality were then estimated using the long‐term decrease of particulate matter as an indicator.