A New Criteria Decision Applied on the Primary Synchronization in the DS-WCDMA Interface of the UMTS System

In DS-WCDMA mobile systems such the UMTS, asynchronous cell site operation,assigning different long spreading code to each cell, yields the advantageof flexible system deployment. We can design an indoor system basedon an outdoor one. However, in general, much longer search time isrequired in asynchronous operation than in synchronous. This paperproposes three techniques to take decisions about synchronizationbased on observation of correlated signals. Classical decision criterialike maximum and threshold criterion are presented. A new decisioncriteria that we call Threshold&Max combined decision criteriais analyzed. The results of this new introduced technique is comparedwith the classical ones.     

Preparation and properties of novel polyurethane insulating coatings based on glycerin‐terminated urethane prepolymers and blocked isocyanate

Novel polyurethane insulating coatings were prepared from the reaction of glycerin‐terminated polyurethane prepolymers (GPUPs) and a blocked isocyanate curing agent (BIC). The GPUPs were prepared from the reaction of one equivalent of polycaprolactone polyol (CAPA 210) with an excess amount of 4,4′‐methylene bis(phenyl isocyanate) (MDI) and subsequent reaction of the NCO‐terminated polyurethane with glycerin. The BIC was prepared from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). The polyols and curing agent were characterized by conventional methods while the curing condition was optimized via gel content measurements. The curing kinetics of the polyurethane coating were investigated and the kinetic parameters derived. The crosslink densities of the samples were determined via the equilibrium swelling method, using the Flory–Rehner equation. The relationships between the crosslink density and the electrical, physical, mechanical and dynamic mechanical properties of the coatings were also studied. Copyright © 2005 Society of Chemical Industry     

Continuous hydrolysis of olive oil by lipase in microporous hydrophobic membrane bioreactor

Continuous hydrolysis of olive oil byCandida cylindracea’s lipase was studied in a microporous hydrophobic membrane bioreactor. Olive oil and buffer solution, fed continuously through two compartments partitioned by membrane, caused reaction at the interface of lipase-adsorbed membrane and buffer solution. Fatty acid was obtained in a single phase without being mixed with components of other phases. At all mean residence times, countercurrent flow mode was superior to cocurrent one. The lipase was adsorbed onto the membrane, and its adsorption was suggested to be partially specific from the experiments with enzymes having various levels of purity. The percent hydrolysis depended hyperbolically on the interfacial enzyme concentration. The hydrolysis seemed to be limited by diffusion of fat or fatty acid through the micropores of the membrane at higher interfacial enzyme concentrations. The lipase was stabilized significantly by glycerol added to the buffer solution. Satisfactory performance of the membrane bioreactor was obtained in a longterm continuous operation which lasted for 24 days by feeding buffer-glycerol (18.0%) solution over the adsorbed lipase. The operational half-life of the adsorbed enzyme was 15 days at 40 C.     

Structural properties of phosphorous-doped polycrystalline silicon

The structural properties and hydrogen bonding of undoped and phosphorous doped polycrystalline silicon produced by step-by-step laser dehydrogenation and crystallization technique were investigated using Raman spectroscopy and hydrogen effusion measurements. At low laser fluences, E_L, a two-layer system is created. This is accompanied by the change in hydrogen bonding. The intensity of the Si–H vibration mode at 2000 decreases faster than the one at 2100 cm⁻¹. This is even more pronounced in phosphorous-doped specimens. The laser crystallization results in an increase of the hydrogen binding energy by approximately 0.2–0.3 eV compared to the amorphous starting materials.     

Cellular mechanisms for developmental toxicity of chlorpyrifos: targeting the adenylyl cyclase signaling cascade

Developmental neurotoxicity caused by chlorpyrifos exposure is generally thought to target cholinesterase but chlorpyrifos may also act on cellular intermediates, such as adenylyl cyclase, that serve global functions in the coordination of cell development. In the current study, neonatal rats were exposed to apparently subtoxic doses of chlorpyrifos (no weight loss, no mortality) either on Postnatal Days 1-4 or on Postnatal Days 11-14, and the effects on components of the adenylyl cyclase cascade were evaluated in brain regions that are enriched (forebrain) or sparse (cerebellum) in cholinergic innervation, as well as in a nonneural tissue (heart). In all three, chlorpyrifos evoked deficits in multiple components of the adenylyl cyclase cascade: expression and activity of adenylyl cyclase itself, functioning of G-proteins that link neurotransmitter and hormone receptors to cyclase activity, and expression of neurotransmitter receptors that act through this cascade. Disruption of signaling function was not restricted to transduction of cholinergic signals but rather extended to adrenergic signals as well. In most cases, the adverse effects were not evident during the immediate period of chlorpyrifos administration, but appeared after a delay of several days. These results suggest that chlorpyrifos can affect cell development by altering the activity and reactivity of the adenylyl cyclase signaling cascade, a major control point for trophic regulation of cell differentiation. The effects are not restricted to cholinergic targets, nor even to the central nervous system. Hence, disruption of cell development by chlorpyrifos is likely to be more widespread than previously thought.     

A New Image Analysis Based Method for Measuring Electrospun Nanofiber Diameter

In this paper, a new image analysis based method for electrospun nanofiber diameter measurement has been presented. The method was tested by a simulated image with known characteristics and a real web. Mean (M) and standard deviation (STD) of fiber diameter obtained using this method for the simulated image were 15.02 and 4.80 pixels respectively, compared to the true values of 15.35 and 4.47 pixels. For the real web, applying the method resulted in M and STD of 324 and 50.4 nm which are extremely close to the values of 319 and 42 nm obtained using manual method. The results show that this approach is successful in making fast, accurate automated measurements of electrospun fiber diameters.     

Synthesis and activation of Pt nanoparticles with controlled size for fuel cell electrocatalysts

Well-dispersed Pt nanoparticles with controlled size and narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate, using oleylamine as a capping agent. The particle size was varied from 3.5 nm to 11.5 nm by decreasing the amount of oleylamine added in the synthesis. Size selection of the as-prepared particles by solvent fractionation yielded nearly monodispersed Pt particles. The as-prepared particles were loaded on a carbon support by physical deposition, but showed no electrocatalytic activity due to the oleylamine bound to the particle surface. The particles were activated for electrocatalysis after heating the particles in air at 185 °C for 5 h, conditions that gave no particle-sintering and no oxidation. Cyclic voltammetry showed that the particles after the heat treatment in air were electrocatalytically active for methanol oxidation. The smaller 3.5 nm and 4.0 nm Pt particles had a higher intrinsic activity for methanol oxidation, but a lower tolerance to CO poisoning, compared with 6.0 nm, 9.5 nm and 11.5 nm particles. CO-stripping results suggest that CO is more easily oxidized on larger Pt particles.     

Binders for jute-reinforced unsaturated polyester resin

Reinforcement of polyester resin with jute cloth under constant load is studied, The pretreatment of jute cloth with tetrahydrofuran and the effect of binding properties of poly(vinyl acetate) and acrylic acid and their effect on the impact, tensile, and water absorptions of jute cloth polyester composites are reported and their chemical reactions are discussed.     

A Novel UWB Pulse Shape Modulation System

In this paper novel modified Hermite polynomial functions for use in impulse radio (ultra-wideband) communications are proposed. With these functions pulse shapes which are orthogonal and have nearly constant pulse width regardless of the pulse order are generated. These properties hold under the effects of differentiation. An M-ary communication system is constructed using these pulse shapes. A Matlab model for generating the pulses is designed and the effect of timing jitter on the performance of the system is investigated by computer simulation.