Analysis and evaluation of distributed photovoltaic generation in electrical energy production and related regulations of Turkey

Clean Technologies and Environmental Policy - Turkey is a developing country with rising energy demands. Energy access is one of the key parameters to sustain the development, since the country...     

Preparation and drug‐release behavior of minocycline‐loaded poly[hydroxyethyl methacrylate‐co‐poly(ethylene glycol)–methacrylate] films

In this work, biocompatible hydrogel matrices for wound‐dressing materials and controlled drug‐release systems were prepared from poly[hydroxyethyl methacrylate‐co‐poly(ethylene glycol)–methacrylate] [p(HEMA‐co‐PEG–MA] films via UV‐initiated photopolymerization. The characterization of the hydrogels was conducted with swelling experiments, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis (differential scanning calorimetry), and contact‐angle studies. The water absorbency of the hydrogel films significantly changed with the change of the medium pH from 4.0 to 7.4. The thermal stability of the copolymer was lowered by an increase in the ratio of poly(ethylene glycol) (PEG) to methacrylate (MA) in the film structure. Contact‐angle measurements on the surface of the p(HEMA‐co‐PEG–MA) films demonstrated that the copolymer gave rise to a significant hydrophilic surface in comparison with the homopolymer of 2‐hydroxyethyl methacrylate (HEMA). The blood protein adsorption was significantly reduced on the surface of the copolymer hydrogels in comparison with the control homopolymer of HEMA. Model antibiotic (i.e., minocycline) release experiments were performed in physiological buffer saline solutions with a continuous flow release system. The amount of minocycline release was shown to be dependent on the HEMA/PEG–MA ratio. The hydrogels have good antifouling properties and therefore are suitable candidates for wound dressing and other tissue engineering applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Spectral characterisation and computational studies of some novel phenylazoindol‐2‐one dyes

A series of novel phenylazo disperse dyes were prepared by coupling selected diazotised 3‐ or 4‐anilines with indol‐2‐one. The structures of the synthesised dyes were determined by spectroscopic and analytical methods. Solvent effects on the ultraviolet–visible absorption spectra of these novel dyes were studied. The colour of the dyes was evaluated with respect to the substituent therein. Acid and base effects on the visible absorption maxima of the dyes were also reported. The tautomerism of 3‐(phenyldiazenyl)indol‐2‐one was modelled by density functional theory at the B3LYP level. The ultraviolet–visible absorption spectra for the tautomers were reproduced with the time‐dependent density functional theory and semi‐empirical Zerner’s intermediate neglect of differential overlap/spectroscopic (ZINDO/S) method. The predominance of the keto–hydrazone tautomer was confirmed experimentally and theoretically.     

A bicriteria parallel machine scheduling with a learning effect

Conventionally, job processing times are assumed to be constant from the first job to be processed until the last job to be completed. However, recent empirical studies in several industries have verified that unit costs decline as firms produce more of a product and gain knowledge or experience. This phenomenon is known as the “learning effect.” In this paper a bicriteria m-identical parallel machine scheduling problem with a learning effect is considered. The objective function of the problem is to find a sequence that minimizes a weighted sum of total completion time and total tardiness. Total completion time and total tardiness are widely used performance measures in scheduling literature. To solve this scheduling problem, a mathematical programming model is formulated.     

Comparison of PWM and PFM induction drives regarding audible noise and vibration for household applications

This paper is aimed at comparing the performance of pulse frequency modulation (PFM) and pulsewidth modulation (PWM) techniques regarding audible noise generated from inverter-driven induction motors. For the purpose of illustrating the performance of the two modulation techniques, a drive developed for washing machine applications is considered. First, the measured and simulated harmonic content of this inverter is compared with the measured harmonic spectrum of a three-phase input-output commercial variable-frequency inverter. It is found that despite the 8-bit processor inexpensive implementation, the total harmonic distortion (THD) of PFM is comparable to the THD of PWM in more sophisticated applications. It is discovered that the harmonic spectrum of PFM exhibits harmonics of smaller magnitude distributed over 0.9f/sub o/--2.1f/sub o/ (base switching frequency) range, as opposed to a smaller number of dominant harmonics of PWM. Next, the prototype drive is programmed to generate both sine-PWM and PFM waveforms. The motor is driven at several frequencies and the audible noise and vibration level of the motor is measured. It is observed that the type of current harmonic content of PFM leads to reduced noise and vibration.     

A new in vitro/in vivo kinetic correlation method for nitrofurantoin matrix tablet formulations

The kinetic distributions of in vitro percentage release and in vivo percentage urinary excretion rates of nitrofurantoin from matrix tablets were plotted using a kinetic program. In vitro release rates were determined using the USP paddle and half-change methods. Urinary excretion curves of the drug were characterized by means of the statistical moments. The individual linear correlations between each in vitro and in vivo kinetic distribution were established, and regression equations were calculated. The application results of the best correlations obtained were evaluated according to in vivo results. A reversed kinetic procedure was applied for transformation of the correlated kinetic values to the drug percentage release rates. The modified Langenbucher kinetic showed excellent linear correlation (r = .9985). The method that is proposed in this study, the kinetic correlation program, is simple, independent of time, and suggests that it is possible to use kinetic distributions in the in vitro/in vivo correlation. This study also suggests using kinetic correlation to investigate the suitability of the in vitro dissolution methods with the in vivo drug dissolution.     

Evaluating Enzymatic Productivity—The Missing Link to Enzyme Utility

Kinetic productivity analysis is critical to the characterization of enzyme catalytic performance and capacity. However, productivity analysis has been largely overlooked in the published literature. Less than 0.01% of studies which report on enzyme characterization present productivity analysis, despite the fact that this is the only measurement method that provides a reliable indicator of potential commercial utility. Here, we argue that reporting productivity data involving native, modified, and immobilized enzymes under different reaction conditions will be of immense value in optimizing enzymatic processes, with a view to accelerating biotechnological applications. With the use of examples from wide-ranging studies, we demonstrate that productivity is a measure of critical importance to the translational and commercial use of enzymes and processes that employ them. We conclude the review by suggesting steps to maximize the productivity of enzyme catalyzed reactions.     

Impact of solids residence time on biological nutrient removal performance of membrane bioreactor

Impact of long solids residence times (SRTs) on nutrient removal was investigated using a submerged plate-frame membrane bioreactor with anaerobic and anoxic tanks. The system was operated at 10, 25, 50 and 75 days SRTs with hydraulic retention times (HRTs) of 2 h each for the anaerobic and anoxic tanks and 8 h for the oxic tank. Recirculation of oxic tank mixed liquor into the anaerobic tank and permeate into the anoxic tank were fixed at 100% each of the influent flow. For all SRTs, percent removals of soluble chemical oxygen demand were more than 93% and nitrification was more than 98.5% but total nitrogen percent removal seemed to peak at 81% at 50 days SRT while total phosphorus (TP) percent removal showed a deterioration from approximately 80% at 50 days SRT to 60% at 75 days SRT. Before calibrating the Biowin^® model to the experimental data, a sensitivity analysis of the model was conducted which indicated that heterotrophic anoxic yield, anaerobic hydrolysis factors of heterotrophs, heterotrophic hydrolysis, oxic endogenous decay rate for heterotrophs and oxic endogenous decay rate of PAOs had the most impact on predicted effluent TP concentration. The final values of kinetic parameters obtained in the calibration seemed to imply that nitrogen and phosphorus removal increased with SRT due to an increase in anoxic and anaerobic hydrolysis factors up to 50 days SRT but beyond that removal of phosphorus deteriorated due to high oxic endogenous decay rates. This indirectly imply that the decrease in phosphorus removal at 75 days SRT may be due to an increase in lysis of microbial cells at high SRTs along with the low food/microorganisms ratio as a result of high suspended solids in the oxic tank. Several polynomial correlations relating the various calibrated kinetic parameters with SRTs were derived. The Biowin^® model and the kinetic parameters predicted by the polynomial correlations were verified and found to predict well the effluent water quality of the MBR at 35 days SRT.     

Ochratoxin A and Brewing Technology: A Review

Ochratoxins are a hazardous group of mycotoxins produced as secondary metabolites by several fungi of the Aspergillus and Penicillium families. Ochratoxins have been detected and determined in foods and beverages, including barley, malt and beer, at ppb levels. Varied analytical methods have been developed for the detection of ochratoxin A [OTA] in cereals and beer. Ochratoxin A has hazardous effects on health and has been classified within group 2B, as a possible human carcinogen by IARC. Scientists have expressed great concern about the presence of ochratoxin A in foods. In this article, chemical structure, biosynthesis by microorganisms, analytical methods for testing, regulations, changes during brewing, and detoxification of OTA, are reviewed. Beer poses very little risk as a source of ochratoxin in the diet.