The design of multiple feedback topology Chebyshev low-pass active filter with average differential evolution algorithm

Neural Computing and Applications - This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are...     

The effect of cholinergic drugs on [3H]acetylcholine release from slices of rat hippocampus, striatum and cortex

Slices from rat hippocampus, striatum or cortex were incubated with l mum [3H] choline and following 75 min superfusion with Krebs solution the efflux of radioactivity was measured. The slices were stimulated either electrically (1 Hz) or with 25 mM potassium and the rate constant of the evoked release and the size of the releasable pool were estimated. The spontaneous efflux of radioactivity and the releasable pool but not the rate of evoked release correlated with the reported endogenous ACh content of the 3 areas. Raised potassium released radioactivity at a lower rate but from a larger pool than electrical stimulation from all 3 areas. In all 3 areas atropine alone potentiated while physostigmine, oxotremorine and carbamylcholine decreased the rate of evoked release. This depression was fully antagonized by atropine. The drugs had no effect on the size of the releasable pool. Findings suggest that muscarinic receptors located on cholinergic axons or terminals have a physiological role in the autoregulation of ACh release from these 3 areas.     

Investigation of microstructure and wear behaviors of al matrix composites reinforced by carbon nanotube

In this study, the effect of CNT amount in Al-CNT composites produced by adding carbon nanotube (CNT) to 7075 Al alloy in various amounts on microstructure and wear behaviors of aluminum matrix composites was investigated. CNT was added to 7075 Al alloy powder at five different amounts. The powders were mechanically milled for 2 hours. Mechanical milled powders were cold pressed and then pre-shaped by hot pressing. Pre-shaped samples were sintered for 1 hour under 10^?6 millibar in 580°C. Microstructure examinations, hardness measurements, and wear tests were carried out. The results show that CNT's in the microstructure were agglomerated as nanotube amount increases and there was no uniform distribution. The highest hardness value was obtained in AMC reinforced with 1% CNT while it is seen that hardness of the composite decreases and weight loss increases as CNT amount increases.     

Novel synthesis medium for poly(aniline-co-o-anisidine)

Aqueous sodium oxalate (NaOX) solutions both without (1) and with (2) p-toluenesulfonic acid (p-TSA) were used to synthesize a poly(aniline-co-o-anisidine) (PANI-co-POA) film on mild steel (MS). Polarization of the substrate in p-TSA containing NaOX solution mixture led to the passivation of the surface mainly via the formation of an iron(II) oxalate layer. Copolymer coatings showed that p-TSA + NaOX solution mixture was a suitable medium for the deposition of a uniform, compact and strongly adherent PANI-co-POA coating on MS electrode. Similar coating was achieved when NaOX solution was used free of p-TSA. It was observed that addition of p-TSA in NaOX solution provided also an increase in electropolymerization rate. Evaluation of the anticorrosion performance of copolymer coatings in 3.5% NaCl solution was investigated by using AC impedance spectroscopy (EIS) technique and anodic polarization curves. Both copolymer coatings exhibited a significant physical barrier property against the attack of corrosive products on mild steel, in longer periods.     

The frequency of left atrial spontaneous echo contrast and its clinical significance in mitral valve insufficiency

The authors investigated the frequency of left atrial spontaneous echo contrast in mitral valve disease. They also tested whether there was any correlation between the presence of left atrial spontaneous echo contrast and the severity of the mitral valve disease. Echocardiographic investigations were performed using both transthoracal and transesophageal echocardiographic methods employing monoplane transducer. The authors carried out 273 transesophageal investigations over a period of 2 years and found left atrial spontaneous echo contrast in 85 patients, who had mitral valve disease. Of this, in 18 cases thrombi were also detected in the left atrium and/or auricula. The diagnoses of mitral stenosis were made in 24 patients, of whom in 12 cases the stenosis were found to be severe, whilst in 12 cases to be moderate. Furthermore insufficiency of the mitral valve was detected in 35 cases. 20 patients had artificial mitral valve implanted, they received long term anticoagulant treatment. 59 patients had no spontaneous echo contrast. 14 patients had previous embolic events of which 9 were cerebral and in other cases arteries of the kidney, eye and extremities were affected. 71 patients had no history of embolism. The authors concluded that mitral valve disease, particularly mitral stenosis is frequently associated with left atrial spontaneous echo contrast. It has been also observed, that the more severe the mitral valve disease, the greater the probability of left atrial spontaneous echo contrast. In all cases where thrombi were found, left atrial echo contrast were demonstrated and the risk of embolism is high. In these cases anticoagulant therapy is suggested.     

Incremental gravitational search algorithm for high-dimensional benchmark functions

Neural Computing and Applications - In this study, gravitational search algorithm (GSA), which is a powerful optimization algorithm developed in recent years and based on physics, is improved by...     

Investigation of the Effect of Ni Amount on the Wear Performance of A356 Cast Aluminum Alloys

Metallurgist - This study investigates the effect of artificial aging treatment on wear performance of A356 alloy containing different amounts of Ni. Within the scope of the study, A356/Ni alloys...     

Experimental Study of Flow Reversal Ammonia Synthesis

Operation of fixed bed reactors with periodic flow reversal as proposed by Matros and co-workers is an unconventional mode of operation for exothermic, equilibrium limited catalytic reactions. In the present paper, reverse flow ammonia synthesis at 240–300 bar over a promoted iron catalyst is considered. The catalyst had a particle size of 1.0–1.5 mm to neglect the intra- and interparticle transport intrusions. Temperature profiles, which developed and moved back and forth through the laboratory scale reactor, depending upon the direction of the flow, and the exit ammonia concentration were monitored. The time average ammonia concentration observed in the non-steady-state of operation was exceeded by 5–27% the ammonia concentration obtained in similar but under steady-state conditions. The enhancement in the ammonia production was mainly due to the transient state of the catalyst surface and the dynamic behavior of the reactor bed.     

Bicycle injuries in children: An analysis based on demographic density

IntroductionThe purpose of this study was to investigate the characteristics and the outcome of bicycle injuries in paediatric patients according to the living environment, and to create guidelines for injury prevention.PatientsThe evaluation was performed in part based on hospital database of 1803 in- and out-patient children treated at the Paediatric Surgical Department of Pécs/Hungary between 2000 and 2006, and at the Department of Paediatric Surgery at the Heim Pal Hospital Budapest between 2004 and 2006. Additionally questionnaires were mailed to the patients’ families to gain follow-up information. We analysed three groups according to demographic density (village, midsize town and large town).ResultsWe found, that poor road quality played an important role as a contributing factor of injuries in villages. The number of bicycle spoke-injuries was higher in villages (13%), than in midsize towns (4.6%) and the large town (9.9%). In villages, 5% of children injured wore a helmet; this rate was 9% in midsize towns and 9.1% in the large town. Head injury was more common in villages, while in midsize towns and the large town arm injuries proved to be predominant.DiscussionPrevention strategies targeting bicycle injuries in children should take into account the population density. This analysis revealed a substantial difference in the use of safety devices, and in the characteristics of injuries occurring in villages, indicating that there is a need for special attention regarding this higher risk population.     

Stability test of novel combined formulated dry powder inhalation system containing antibiotic: physical characterization and in vitro–in silico lung deposition results

Objective: The aim was to study the stability of dry powder inhaler (DPI) formulations containing antibiotic with different preparation ways – carrier-based, carrier-free, and novel combined formulation – and thereby to compare their physicochemical and in vitro–in silico aerodynamical properties before and after storage. Presenting a novel combined technology in the field of DPI formulation including the carrier-based and carrier-free methods, it is the most important reason to introduce this stable formulation for the further development of DPIs.

Methods: The structure, the residual solvent content, the interparticle interactions, the particle size distribution and the morphology of the samples were studied. The aerodynamic values were determined based on the cascade impactor in vitro lung model. We tested the in silico behavior of the novel combined formulated samples before and during storage.

Results: The physical measurements showed that the novel combined formulated sample was the most favorable. It was found that thanks to the formulation technique and the use of magnesium stearate (MgSt) has a beneficial effect on the stability compared with the carrier-based formulation without MgSt and carrier-free formulations. The results of in vitro and in silico lung models were consistent with the physical results, so the highest deposition was found for the novel combined formulated sample during the storage.

Conclusions: It can be established that after the storage a novel combined formulated DPI contained amorphous drug to have around 2.5?μm mass median aerodynamic diameter and nearly 50% fine particle fraction predicted high lung deposition in silico also.