Copper/polypyrrole multilayer coating for 7075 aluminum alloy protection

The corrosion behavior of 7075 aluminum (Al), copper modified Al (Al/Cu), polypyrrole modified Al (Al/PPy) and copper (under layer)/polypyrrole (top layer) modified Al (Al/Cu/PPy) samples were investigated in 3.5% NaCl solution. The copper plating on aluminum was carried out from acidic copper sulphate solution by electroless method. Polypyrrole (PPy) was electrochemically synthesized on Al and Al/Cu electrodes from 0.1 M pyrrole containing 0.4 M oxalic acid solution using cyclic voltammetry technique. The films synthesized were characterized by Fourier transform infrared spectroscopy (FT-IR). The thermal stability of PPy films was investigated by thermogravimetric analysis (TGA). The surface morphologies were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The corrosion behavior of samples was investigated by electrochemical impedance spectroscopy (EIS) and anodic polarization curves. The data obtained showed that the synthesis of PPy on top of the Cu layer significantly enhances the corrosion resistance of Al by exhibiting a barrier effect against the attack of corrosive environment.     

Inhibitory effects of selected pesticides on peroxidases purified by affinity chromatography

The objective of this study was to determine the in vitro inhibition effects of seven commonly used pesticides including 2,4-d-acid dimethylamine, fenoxaprop-p-ethyl, glyphosate isopropylamine, haloxyfop-p-methyl, cypermethrin, λ-cyhalothrin, and dichlorvos on the peroxidase purified from turnip (Brassica rapa L.) and black radish (Raphanus sativus L.) using 4-amino benzohydrazide affinity column chromatography. The purification factors for the turnip and black radish peroxidases were found to be 263.29-fold (with a yield of 12.89%) and 36.20-fold (with a yield of 6.90%), respectively. Among these compounds, λ-cyhalothrin showed the strongest inhibitory effect against turnip peroxidase (K_i: 1.23 × 10^?2 ± 0.21 × 10^?2 mM) as noncompetitive inhibition. On the other hand, cypermethrin demonstrated the highest inhibition effect against black radish peroxidase (K_i: 2.14 × 10^?2 ± 0.08 × 10^?2 mM) as competitive inhibition.     

Catalytic-kinetic spectrophotometric determination of vanadium （V） based on the Celestine blue-bromate-vanadium （V）-citric acid reaction

A novel sensitive and relatively selective kinetic method is presented for the determination of V(V) based on its catalytic effect on the oxidation reaction of Celestine blue by potassium bromate in the presence of citric acid as an activator.The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Celestine blue at a maximum absorption wavelength of 540 nm between 0.5 and 9 min(the fixed-time method) in an H3PO4 medium at 45°C.The effect of various parameters such as con...     

Catalytic-kinetic spectrophotometric determination of vanadium (Ⅴ) based on the Celestine blue-bromate-vanadium (Ⅴ)-citric acid reaction

A novel sensitive and relatively selective kinetic method is presented for the determination of V(Ⅴ) based on its catalytic effect on the oxidation reaction of Celestine blue by potassium bromate in the presence of citric acid as an activator.The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Celestine blue at a maximum absorption wavelength of 540 nm between 0.5 and 9 min (the fixed-time method) in an H3PO4 medium at 45℃.The effect of various parameters such as concentrations of H3PO4,citric acid,potassium bromate and Celestine blue,ionic strength,reaction temperature and time on the rate of V(Ⅴ) catalyzed reaction was studied.The method is free from the most interferences,especially from large amounts of V(Ⅳ).The decrease in absorbance is proportional to the concentration of V(Ⅴ) over the entire concentration range tested (0.025-1.25 μg·mL-1) with a detection limit of 6.80 μg·L-1 (according to statistical 3Sblank/k criterion) and a coefficient of variation (CV) of 1.78％ (for ten replicate measurements at 95％ confidence level).The proposed method suffers from a few interferences such as Cr(Ⅵ) and Hg(Ⅱ) ions.The method was successfully applied to the determination of V(Ⅴ) in river water,lake water,tap water,natural drinking water samples and a certified standard reference material such as SRM-1640 with satisfactory results.The vanadium contents of natural water samples were detected by using both linear calibration curve and standard addition curve methods.The recoveries of spiked vanadium (Ⅴ) into the certified standard water sample were found to be quantitative,and the reproducibility was satisfactory.It was observed that the results of the SRM 1640 were in good agreement with the certified value.     

Erythrocyte folate status and serum iron levels in patients undergoing hemodialysis

The present study was aimed to evaluate erythrocyte folate and the iron levels in diabetes and hypertension patients treated with/without hemodialysis. The effects of erythropoietin and iron treatment as well as vitamin supplementation on measured parameters were considered. The 67 controls consisted of healthy subjects (n = 22), hypertensive subjects (n = 22), and diabetic subjects (n = 23) without any renal disorder. According to primary renal disorders, the patients undergoing hemodialysis (n = 68) were classified into four groups as diabetic nephropathy, hypertensive nephropathy, reflux nephropathy or interstitial nephritis, and renal insufficiency depending on other causative factors. The mean value of erythrocyte folate levels of all patients undergoing hemodialysis was higher than the healthy control group (P < 0.05). Erythrocyte folate levels in hypertensive and diabetic nephropathy patients were higher than their own hypertensive or diabetic controls and also healthy controls (both, P < 0.05). Serum iron levels of all subgroups in hemodialysis patients were found to be similar with healthy controls (all, P > 0.05). The only significance observed within the subgroups was between diabetic controls and diabetic nephropathy patients (P < 0.05). None of the treatment or supplementation of erythropoietin, iron and vitamin affected erythrocyte folate levels (all, P > 0.05). The increase in erythrocyte folate status of patients with end stage renal diseases might be the result of sum or individual effects of causative factors such as renal pathology, compensation mechanism against renal anemia, or routine folate supplementation.     

Effects of different drying treatments on fungal population and ochratoxin A occurrence in sultana type grapes

This study aimed to determine the changes in mould and ochratoxin A (OTA) occurrence in sultanas under three different conventional drying conditions. Five different vineyards were chosen, and the three different treatments were applied to these grapes while drying. At the end of the drying process, total mould and black aspergilli (BA) populations in the samples varied from 2.45 to 5.61 log colony-forming units (CFU) g^–1 and from 0 to 4.92 log CFU g^–1, respectively. Significant increases (p < 0.05) occurred in mould loads depending on the extending drying period. However, independent of vineyard location, all the samples treated with cold dipping solution showed the lowest fungal loads. These results indicate that dipping solution treatment was the most effective drying method to minimise fungal infection of grapes. The expected results could not be achieved by drying grapes artificially contaminated with ochratoxigenic Aspergillus carbonarius spores. Seventy-one of 96 isolates (73.95%) obtained during drying were Aspergillus spp., and the remaining (n = 25, 26.05%) belonged to other genera, such as Penicillium, Trichoderma and Cladosporium. Grape juice-based agar medium was used to determine the realistic OTA production capacities of the isolated mould strains. The highest OTA production capacities were 809.70 ± 9.19, 87.58 ± 16.89 and 45.44 ± 18.78 ng g^–1 in 50% grape juice agar (GJ50), all five of which were from A. niger isolates. OTA was not present in any sample during the drying period; however, OTA was detected in two samples at 0.32 ± 0.15 and 0.52 ± 0.36 µg kg^–1 after the end of the drying process. The limit of detection (LOD) and limit of quantitation (LOQ) of the method used for detecting OTA in samples were 0.1 and 0.3 µg kg^–1, respectively.     

Synthesis,characterization and thermal properties of a novel star polymer consisting of poly(ε-caprolactone) arms emanating from an octa-functional porphyrazine core

Octaarmed star-shaped poly(ε-caprolactone) (OSPCL) was successfully synthesized via the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with a magnesium porphyrazine as the multisite initiator and tin(II) 2-ethylhexanoate (Sn(Oct₂)) as the catalyst in bulk at 115 °C. The star polymer has a central Mg-porphyrazine surrounded by ε-CL arms. OSPCL was characterized by ¹H NMR, FTIR, GPC and UV–vis, and fluorescent spectroscopy. The effect of the molar ratio of the monomer to the initiator on molecular weight of the polymer was also investigated. The molecular weight of the polymer linearly increased with increasing molar ratio of the monomer to the initiator. The crystallization behavior of OSPCL was studied using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). OSPCL displayed an interrupted crystal morphology owing to its highly branched architecture, and consequently, the degree of crystallinity was lower in comparison with the linear analogue. Thermogravimetric analysis (TGA) clearly indicated that incorporation of porphyrazine core enhanced the thermal stability of the resulting polymers.     

Psychological Symptoms Are Greater in Caregivers of Patients on Hemodialysis Than Those of Peritoneal Dialysis

Background: The purpose of this study was to evaluate and compare psychosocial characteristics in caregiving relatives (caregivers) of hemodialysis (HD) and peritoneal dialysis (PD) patients. Methods: Thirty‐three caregivers (17 women, 16 men) of HD patients, 27 caregivers (11 women, 16 men) of PD patients, and a control group of 49 subjects who do not care for family members with chronic illness (23 women, 26 men) are included in this study. The brief symptom inventory (BSI), social disability schedule (SDS), and brief disability questionnaire (BDQ) were used for the psychosocial evaluation. Results: The mean age, men‐to‐women ratios, duration of education, and distribution of marital status did not differ significantly among the three groups. In addition, dialysis duration and distribution of caregiver type were not different between the HD and PD groups. Although the mean global severity index scores of the three groups were similar, somatization and depression scores from BSI subitems were greater in the HD group than the scores of the PD and control groups. Although the mean SDS and BDQ scores were higher in the HD group, the differences did not achieve statistical significance. BSI subitems such as somatization, obsession–compulsion, interpersonal sensitivity, depression, and anxiety were positively correlated among themselves. Hostility and somatization were negatively correlated with age and education, respectively. Nevertheless, somatization was positively correlated with age. Social disability was negatively correlated with duration of education. Conclusion: Somatization and depression are greater in the caregivers of center HD patients compared to PD and control groups. According to the findings of this study, we suggest that caregiving family members of dialysis patients especially on HD also should be evaluated for psychosocial problems and supported as needed. Further studies are needed to explore whether psychosocial parameters of caregivers predict outcomes for caregivers and patients.     

Superparamagnetic flexible substrates based on submicron electrospun Estane® fibers containing MnZnFe?Ni nanoparticles

Flexible, elastomeric, and superparamagnetic substrates were prepared by electrospinning a solution of elastomeric polyurethane containing ferrite nanoparticles (～14 nm) of Mn? Zn? Ni. The flexible mats were characterized in terms of fiber morphology and magnetic properties. Field emission scanning electron microscopy (FESEM) indicated that the diameter of these composite fibers was ～300–500 nm. Furthermore, the back‐scattered electron FESEM images indicated agglomeration of the nanoparticles at higher wt % (ca. 17–26 wt %) loading in the electrospun fibers. The induced specific magnetic saturation and the relative permeability were found to increase linearly with increasing wt % loading of the ferrite nanoparticles on the submicron electrospun fibers. A specific magnetic saturation of 1.7–6.3 emu/g at ambient conditions indicated superparamagnetic behavior of these composite electrospun substrates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4935–4942, 2006     

Equilibrium, kinetic and thermodynamic studies of adsorption of Pb(II) from aqueous solution onto Turkish kaolinite clay

The adsorption of Pb(II) onto Turkish (Bandirma region) kaolinite clay was examined in aqueous solution with respect to the pH, adsorbent dosage, contact time, and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well. The monolayer adsorption capacity was found as 31.75 mg/g at pH 5 and 20 degrees C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. The mean free energy of adsorption (13.78 kJ/mol) indicated that the adsorption of Pb(II) onto kaolinite clay may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (deltaG degrees ), enthalpy (deltaH degrees ) and entropy (deltaS degrees ) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto kaolinite clay was feasible, spontaneous and exothermic process in nature. Furthermore, the Lagergren-first-order, pseudo-second-order and the intraparticle diffusion models were used to describe the kinetic data. The experimental data fitted well the pseudo-second-order kinetics.