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.     

Preconcentration and determination of copper and cadmium ions with 1,6-bis(2-carboxy aldehyde phenoxy)butane functionalized Amberlite XAD-16 by flame atomic absorption spectrometry

A new chelating resin, covalently linked 1,6-bis(2-carboxy aldehyde phenoxy)butane with the Amberlite XAD-16 was synthesized and used for preconcentration of Cu(II) and Cd(II) prior to their determination by flame atomic absorption spectrometry (FAAS). It was characterized by elemental analyses and Fourier Transform Infrared Spectroscopy (FT-IR). Cu(II) and Cd(II) ions were quantitatively preconcentrated on minicolumn loaded with synthesised resin at pH 4.00 and 6.00, respectively. They were eluated with 5 mL of 0.5 mol L⁻¹ HCl. Recoveries of Cu(II) and Cd(II) were found to be 100 ± 2.15, 100 ± 1.40 (N = 5), the limits of detection of Cu(II) and Cd(II) in the determination by FAAS (3s, N = 20) were found to be 0.33 and 1.19 μg L⁻¹, respectively. The effect of foreign ions on the recovery has been investigated. The proposed method has been applied for the determination of Cu(II) and Cd(II) ions to the real samples collected from Tigris river water in Diyarbak?r and Elaz?? cities in Turkey. Standard addition method and analysis of the certified reference material (NCS-DC 73350) was employed to check the accuracy of the method.     

Thermal and economical analysis of an underground seasonal storage heating system in Thrace

Economical analysis of the solar heating system with seasonal storage, which was established in Edirne (41°39′54″N) in order to provide the heat requirement of buildings, has been fulfilled. Optimum collector area for the heating system has been determined. Total heat requirement of 69% has been met by means of heating system concerning the space heating and domestic water heating. In the accordance with the results of the economical analysis, the payback time of the heating system has been determined as 19-20 years.     

Secondhand smoke exposure and the risk of hearing loss

Hearing loss has been associated with tobacco smoking, but its relationship with secondhand smoke is not known. We sought to investigate the association between secondhand smoke exposure and hearing loss in a nationally representative sample of adults. The National Health and Nutrition Examination Survey (NHANES), a nationally representative cross-sectional dataset, was utilised to investigate the association between secondhand smoke exposure and hearing loss. Data collected from non-smoking participants aged 20-69 years were included in the analysis if they had completed audiometric testing, had a valid serum continue value, and provided complete smoking, medical co-morbidity and noise exposure histories (N=3307). Hearing loss was assessed from averaged pure-tone thresholds over low- or mid-frequencies (500, 1000 and 2000 Hz) and high-frequencies (3000, 4000, 6000 and 8000 Hz), and was defined as mild or greater severity (pure-tone average in excess of 25 dB HL). Second-Hand Smoke (SHS) exposure was significantly associated with increased risk of hearing loss for low-/mid-frequencies (adjusted OR=1.14; 95% CI 1.02-1.28 for never smokers and 1.30; 1.10-1.54 for former smokers) and high-frequencies (1.40; 1.22-1.81 for former smokers), after controlling for potential confounders. Findings from the present analysis indicate that SHS exposure is associated with hearing loss in non-smoking adults.     

Synthesis, characterization and structure effects on preconcentration and extraction of N,N'-bis-(salicylaldehydene)-1,4-bis-(p-aminophenoxy) butane towards some divalent cations

Separation with solvent extraction of Cu(II), Co(II) and Ni(II) from aqueous solution using N,N'-bis-(salicylaldehydene)-1,4-bis-(p-aminophenoxy)butane (H(2)L) as the new extractant has been studied. The new Schiff base, was synthesized by reaction of 1,4-bis-(p-aminophenoxy)butane and salicylaldehyde. Microanalytical data, elemental analysis, UV-vis (1)H NMR and (13)C NMR spectra and IR-spectra were used to confirm the structures. The extractability and selectivity of divalent cations was evaluated as a function of relationship between distribution ratios of the metal and pH or ligand concentration. Cu(+2) showed the highest extractability and selectivity at pH 7.8, whereas Ni(+2) and Co(+2) showed at pH 9.2. From the loaded organic phase, Cu(II), Co(II), Ni(II) stripping were carried out in one stage with aqueous acid solution including various concentrations of HCl. The stripping efficiency was found to be quantitative in case of 1.5M HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complexes extracted are the simple 1:1 chelates, CuL, CoL, NiL.     

A comparative study of delayed stroke handling approaches in online handwriting

International Journal on Document Analysis and Recognition (IJDAR) - Delayed strokes, such as i-dots and t-crosses, cause a challenge in online handwriting recognition by introducing an extra...     

Dissipation of organophosphorus pesticides in wheat during pasta processing

For investigating the carryover of some organophosphorus pesticide residues in the cereal food chain from grain to consumer, a study was set up on durum wheat, semolina and pasta. Pesticide-free durum wheat was placed into a small-scale model of a commercial storage vessel and treated with pesticides (malathion, fenitrothion, chlorpyrifos methyl, and pirimiphos methyl) according to the raw material legislation of Turkey. The residue levels of insecticides were determined in wheat, semolina, and spaghetti produced from stored wheat at various time intervals during five months of storage. A multiresidue analysis was performed using GC equipped with an NPD. The confirmation was performed by GC–MS. The residue levels of insecticides in wheat exceeded the maximum residue limits (MRLs) for wheat. The storage period was generally not effective enough to reduce the residues in wheat to levels below the MRLs. Although a considerable amount of the insecticides remained in the semolina, spaghetti processing significantly reduced residue concentrations in general. Pirimiphos methyl was the most persistent of the insecticides and comparatively less substantial loss occurred during milling and spaghetti processing due to its physicochemical properties.     

Biofouling affinity of membrane surfaces under quiescent conditions

Biofouling affinity of four thin film membranes was evaluated under quiescent conditions by exposing the membrane to the effluent from a membrane bioreactor. Coupons of the thin film membranes were left for 5 days in the bioreactor effluent which was filtered through a 0.2 micron filter. The surface morphologies of the membranes before and after the exposure were evaluated by atomic force microscopy (AFM). All membranes showed significant amounts of deposits after the exposure. The easily disturbed nature of the deposits on the polyamide membrane indicated that these deposits were either entrapped within the surface crevices or loosely attached on the membrane. The extent of surface coverage and uniform appearance of the deposits on the polysulfone membrane were indicative of molecular adhesion by functional groups on the membrane surface. Based on the wetting angle measurements, all clean membranes exhibited hydrophilic characteristics. After exposure to the bioreactor effluent, the membranes exhibited complete wetting characteristics. The use of AFM image analysis technique provided insight for the morphological changes and substrate accumulation patterns on membrane surfaces.