Reactive alumina production for the refractory industry

In this study, fine reactive alumina powder production was investigated using Bayer gibbsite as a starting material. Experimental studies consist of three steps; in the first step, the soda content was reduced by means of boric acid and distilled water. In the second step, the effect of heating rate and calcinations temperature on crystal size, phase transformation and surface area were investigated and characterization of the powders was performed by means of XRD and SEM analyses. In the third step, the powders obtained optimum conditions were ground in an attritor mill and then particle size distribution and surface area were measured. The soda content of the gibbsite was reduced from 0.325 to 0.05% by H₃BO₃ treatment, calcination at 1200 °C and then washing in distilled water. The higher the heating rate, the smaller the crystal size is. Alumina ceramics with a density higher than 94.70% of theoretical density were obtained.     

Effects of sowing and harvesting dates on yield and some quality characteristics of crops in sugar beet/cereal rotation system

BACKGROUND: Cereals are the main crops in rotation following sugar beet harvest. However, a delay in planting winter cereals as a result of late sugar beet harvest is a disadvantage in sugar beet/cereal rotations. In this study, field trials were carried out to investigate the effects of sowing and harvesting dates on the yield and quality of sugar beet (Beta vulgaris L.) and cereals (wheat, Triticum aestivum L., and six‐rowed barley, Hordeum vulgare L.) during two consecutive years. Beet was sown on three dates and harvested on four dates, followed by cereals which were sown on four dates. Root yield and digestion ratio (sugar beet) and grain yield, 1000‐kernel weight, test weight and protein content (wheat and barley) were determined. RESULTS: The highest root yield (52.53 t ha^?1) was obtained from early sown (5 April) and late harvested (1 November) beet, while the highest digestion ratio (17.4%) was obtained from late sown (3 May) and late harvested (1 November) beet. Lower cereal grain yields were obtained from later sowings. The highest grain yields (5.87 and 6.02 t ha^?1) were obtained from earlier sown wheat. Protein content was also affected by sowing date, which appeared to be very important under unstable climatic conditions. CONCLUSION: It is essential to consider the timing of sowing of cereal crops when unstable climatic conditions are present. Hence sowing date recommendations in regular climatic conditions may be misleading for countries dependent on winter rainfall for cereal production. Copyright © 2007 Society of Chemical Industry     

Effects of cysteine and different incubation temperatures on the microflora,chemical composition and sensory characteristics of bio-yogurt made from goat’s milk

Yogurt and bio-yogurts were made from goat’s milk using a starter culture and probiotic culture, with or without cysteine addition (0.5%). Incubation was carried out at 37 and 42 °C until pH 4.6 was reached and yogurts were stored 4 ± 1 °C for 14 days. Yogurts were analysed 1, 7 and 14 days after production. The addition of cysteine, incubation temperature and storage time significantly influenced overall properties of the samples. During storage, whey separation, pH and acetaldehyde decreased, while lactic acid increased. Viable bacterial counts in all bio-yogurts were above 10⁷ cfu g⁻¹ at the end of storage. Whey separation, titratable acidity and lactic acid contents were lower, while acetaldehyde and viable bacterial counts were higher in the bio-yogurts incubated at 37 °C and supplemented with cysteine, in comparison to other samples. This indicates that lower temperature incubation and addition of cysteine can be used satisfactorily for the manufacture of bio-yogurt.     

Geometric design of slider-crank mechanisms for desirable slider positions and velocities

In problems requiring uniform cutting speeds uniform flow rates etc. slider-crank mechanisms provide economical solutions. Thus, the problem of designing slider-crank mechanisms for desirable slider positions and velocities is handled within a geometric framework in this paper. Here, the rotation of the crank has been related to the translation of the slider through a linear function. A unified methodology comprising the so-called Subdomain, Galerkin methods together with the classical collocation method is implemented to find the values of the parameters involved. The effectiveness of the methodology has been demonstrated on numerical examples. Since more than one solution results from the solution process, it is always possible to form multi-loop mechanisms. Moreover, designs with low velocity errors in the forward stroke exhibit similar feature in the backward stroke too.     

An algorithm for the solution of second order fuzzy initial value problems

In this paper, we state a fuzzy initial value problem of the second order fuzzy differential equations. Here we investigate problems with fuzzy coefficients, fuzzy initial values and fuzzy forcing functions. We propose an algorithm based on alpha-cut of a fuzzy set. Finally we present some examples by using our proposed algorithm.     

Identification and characterisation of lactic acid bacteria isolated from traditional Urfa cheese

In this study, characterisation of dominant strains of lactic flora in traditional Urfa cheese made from sheep's milk was performed using biochemical, phenotypic and genotypic methods. According to the results obtained, the percentage distributions of the lactic acid bacteria isolated were as follows: 48.95% Enterococcus spp., 40.55% Lactococcus spp., 9.10% Lactobacillus spp., 0.69% Streptococcus spp. and 0.69% Leuconostoc spp. The majority of lactococcal isolates showed an atypical phenotype of growing in the presence of 6.5% NaCl. Acidification and bacteriocin production were also determined for each isolate. Four strains showed bacteriocin activity.     

Solid phase extraction enrichment of pesticide mixtures from aqueous solutions: a quantitative FT‐IR analysis

Solid phase extraction of ten commonly used pesticides on activated carbon has been investigated. Enrichment of these pesticides was successfully achieved at ppm levels and samples were then analysed using FT‐IR. The enrichment technique was employed for each pesticide sample individually and their complex mixtures. The FT‐IR technique was employed for the quantitative analysis. According to the results obtained from FT‐IR some pesticides were recovered at 36.8–86.5% whereas 2,4‐D and endosulfan were decomposed during the extraction procedure.     

Dielectric Properties of Coronene Film Deposited onto Silicon Substrate by Spin Coating for Optoelectronic Applications

Silicon - To determine the electrical modulus, dielectric properties, and ac conductivity of Coronene semiconductor layer, we have produced Al/Coronene/n-Si structure by using the thermally...     

Structural,electrical, and electromagnetic properties of cotton fabrics coated with polyaniline and polypyrrole

In this study, the structural, electrical, and electromagnetic properties of cotton fabrics coated with polyaniline (PAni) and polypyrrole (PPy) were investigated and compared. For the aims, anilin and pyrrole were used as monomers, and in situ polymerization on cotton fabric by chemical oxidative polymerization was performed. After production, the structural properties of the fabrics were determined with Fourier transform infrared spectroscopy and X‐ray diffraction. In addition, ultraviolet (UV) permeability, tensile strength, colorfastness, and electrical and electromagnetic measurements of the fabric samples were carried out. The resistance values of the cotton fabrics coated with PAni and PPy were found to be 350 and 512 Ω, respectively. The average electromagnetic shielding efficiency and average absorption values of the cotton fabrics coated with PAni were determined to be 3.8 dB and 48%, respectively, and these values for the cotton fabrics coated with PPy were 6 dB and 50%, respectively. Consequently, a significant difference was not observed between the resistance values and electromagnetic parameters of the fabrics coated with PAni and PPy, although the intact textile characteristics of the fabric coated with PPy were protected and improved, whereas the characteristics of the fabric coated with PAni were inferior. Moreover, we first report that the fabrics coated with conductive polymers had excellent UV‐protection properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009