Thermal-diffusion and diffusion-thermo effects on combined heat and mass transfer by hydromagnetic three-dimensional free convection over a permeable stretching surface with radiation

The thermal-diffusion and diffusion-thermo effects on the heat and mass transfer characteristics of free convection past a continuously stretching permeable surface in the presence of magnetic field, blowing/suction and radiation are studied. The fluid viscosity is assumed to vary with temperature. The resulting, governing three-dimensional equations are transformed using a similarity transformation and then solved numerically by the shooting method. Comparison with previously published work is performed and full agreement is obtained. A parametric study showing the effects of variable viscosity parameter β, magnetic parameter M, Dufour number Df, Soret number Sr, radiation parameter R and blowing/suction parameter f₀ on the velocity, temperature, and concentration field of a hydrogen-air mixture as a non-chemical reacting fluid pair, as well as the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number is carried out. These are illustrated graphically and in tabular form to depict special features of the solutions.     

The influence of heat transfer and magnetic field on peristaltic transport of a Newtonian fluid in a vertical annulus: Application of an endoscope

This Letter discusses the influence of heat transfer and magnetic field on the peristaltic flow of Newtonian fluid in a vertical annulus under a zero Reynolds number and long wavelength approximation. The inner tube is uniform, rigid, while the outer tube has a sinusoidal wave traveling down its wall. The flow is investigated in a wave frame of reference moving with velocity of the wave. Numerical calculations are carried out for the pressure rise and frictional forces. The features of the flow characteristics are analyzed by plotting graphs and discussed in detail.     

Novel flame retardant paint based on Co(II) and Ni(II) metal complexes as new additives for surface coating applications

The study is focused on the synthesis of a new Co(II) and Ni(II) metal complexes, which is synthesized by the reaction of the isatin 4‐aminoantipyrine Schiff base ligand with selected divalent Co(II) and Ni(II) ions and their possible applications as flame retardant additives in paint formulations for surface coating application. The prepared metal complexes were characterized using a combination of Fourier transform infrared, elemental analysis, proton nuclear magnetic resonance, ¹³C‐NMR spectra, and mass spectroscopy. The prepared Schiff base ligand metal complexes were physically added to alkyd paint formulation to give coating formulations at a laboratory scale and then applied onto plywood and steel panels using a brush. The ignitability and oxygen index values obtained indicated that the paint which contained the prepared Co(II) and Ni(II) metal complexes as additives exhibited very good flame retardant. The physical and mechanical characteristics of the coatings were studied in order to estimate any disadvantages due to the incorporation of the additives. It was discovered that the added substances did not impact the hardness, flexibility, and adhesion of the prepared coating films. The gloss of the paint formulation film was improved due to the incorporation of the aromatic ring into the formulation and the level of the oil percent.     

The impact of indium metal as a minor bimetal on the anodic dissolution and passivation performance of zinc for alkaline batteries: part I—potentiodynamic,potentiostatic, XRD,SEM, and EDAX studies

Journal of Solid State Electrochemistry - Zinc metal is an important element that can be used for long-life alkaline batteries. In this work, it is found that the addition of minor amounts of...     

Spectrophotometric Methods for the Determination of Chloramphenicol,Dexamethasone Sodium Phosphate,and Tetrahydrozoline HCl in their Pure and Ophthalmic Dosage Forms

Journal of Applied Spectroscopy - Chloramphenicol (CHL), dexamethasone sodium phosphate (DSP), and tetrahydrozoline HCl (THZ) are co-formulated for conjunctivitis treatment. The ternary mixture...     

Metastable and stable pitting events at zinc passive layer in alkaline solutions

The electrochemical behavior of Zn in 0.5 M NaOH solutions containing various concentrations (0.01–0.1 M) of ClO₃ ^? or ClO₄ ^? anions was studied with potentiodynamic anodic polarization and chronoamperometry techniques. Microstructural and topographical characterization of the pitted surfaces was carried out by ex situ scanning electron microscopy and atomic force microscopy examinations. Addition of either ClO₃ ^? or ClO₄ ^? stimulated general corrosion and ruptured the passive layer (stable pitting), with ClO₃ ^? being more aggressive than ClO₄ ^?. Metastable pitting events appear as current oscillations (spikes) at potentials close to the pitting potential when Cl^? ions are produced by cathodic reduction of ClO₃ ^? and ClO₄ ^? before passive layer growth. Current–time measurements are performed at fixed potential after production of Cl^? ions and show that the rate of metastable pitting and the intensity of current spikes increase with the potential and the concentration of aggressive anions. Concepts of thin film growth are applied to the passive layer formation in order to explain those results. Metastable events are related to the presence of defects in the passive layer because their frequency and intensity are enhanced in conditions that favor defect formation and roughening in growing films, while stable pitting typically occurs at regions of high metal disorder.     

Analytical procedure to simultaneously measure trace amounts of trenbolone acetate and beta-trenbolone residues in porcine muscle using HPLC-UVD and MS

The current study was undertaken to validate the performance for the determination of both TBA and beta-trenbolone (beta-TB) residues in porcine muscle at concentrations required to monitor compliance with the maximum residue limit (MRL). The method involves a one phase liquid-liquid extraction, cleanup with low-temperature fat precipitation, separation of the respective compounds by HPLC on a Capcell pak C(18) column, use of a methanol-water isocratic system as an eluent, and measurement by UV absorbance detection at 340 nm. Both compounds were confirmed using LC-MS/MS with electrospray interface (ESI) and a triple quadrupole (QqQ) analyzer. The method was found to be precise and accurate, with a linearity range of 1-10 microg/kg (r(2) >0.973). The intra- and interday precision showed good reproducibility with RSDs < or =13.25%. The LODs were 0.12 and 0.22 microg/kg, and the LOQs were 0.37 and 0.66 microg/kg, for TBA and beta-TB, respectively. The applicability of the method was demonstrated by analyzing real samples collected from major cities in the Republic of Korea. No residues of the selected compounds were detected in any of the samples. The advantages of our method are that it is: selective, sensitive, requires a short time for analysis (13 min), and performs simple sample extraction and clean-up procedure with low-temperature fat precipitation as compared to the previously published methods.     

Microwave-induced combustion synthesis and characterization of NixCo1−xFe2O4 nanocrystals (x = 0.0, 0.4, 0.6, 0.8, 1.0)

A series of Ni-doped cobalt ferrites Ni_xCo1_−xFe₂O₄ (x = 0.0, 0.4, 0.6, 0.8, and 1.0) were prepared using microwave-induced combustion. Nickel, cobalt, and ferric nitrates were used as starting materials and glycine as fuel. The influence of Ni content on the lattice parameter, stretching vibrations, and magnetization was studied. XRD, FTIR, and SEM were used for structure, composition, and morphology investigation. A porous network structure was observed with average particle size 60–67 nm. All samples had a cubic spinel structure. The unit cell parameter “a” decreases linearly with nickel concentration due to the smaller ionic radius of nickel. Magnetization measurements showed that coercivity decreased as Ni content increased; it increased with decreasing temperature.      

Synthesis and reactions of thiosemicarbazides,triazoles, and <Emphasis Type="Italic">Schiff</Emphasis> bases as antihypertensive α-blocking agents

Methyl 2-(thiazol-2-ylcarbamoyl)acetate was synthesized and used as starting material. It was treated with hydrazine hydrate to afford the hydrazide, which was reacted with nitromethane and formaldehyde to give the saturated nitropyrimidine. The hydrazide was reacted with phenyl isothiocyanate to afford the thiosemicarbazide, which was cyclized with ethyl bromoacetate, sodium hydroxide, or sulfuric acid to afford N-phenylthiazolidinone, N-phenyltriazole, and thiadiazolyl derivatives. The methyl 2-(thiazol-2-ylcarbamoyl)acetate was coupled with diazonium salts of aniline, 4-chloroaniline, 4-bromoaniline, or 4-aminobenzenesulfonamide to afford the carbamoyl acetates, which were reacted with 2-aminobenzimidazole, 1,2,4,5-tetrachlorophthalic anhydride, and hydrazine hydrate to afford the corresponding thiazolylmalonamide, tetrachloroisoindolylimide, and tri-azole derivatives. Schiff bases and imides are newly synthesized candidates obtained via simple condensation of the hydrazide with aldehydes, 2,3-pyridinedicarboxylic anhydride, or 1,8-naphthalenedicarboxylic anhydride. The pharmacological screening showed that many of these compounds have good antihypertensive α-blocking activity and low toxicity. Correspondence: Abd El-Galil E. Amr, National Research Center, Applied Organic Chemistry, Dokki, Cairo, Egypt.     

Development of extraction procedures for the determination of imidacloprid: application to residue analysis and dynamics of two formulations in Chinese cabbage

This study was undertaken to investigate whether an additional column clean-up procedure can affect the accuracy of an analytical method developed for the determination of imidacloprid residues in Chinese cabbage. Thereafter, the residue levels and the degradation rates of imidacloprid were investigated in experimental Chinese cabbage plots after treatment with two different commercial formulations: emulsifiable concentrate (EC) and wettable powder (WP). The analyte was determined using high-performance liquid chromatography-ultraviolet detection (HPLC-UVD) and confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) in the select ion-monitoring mode. The mean recoveries ranged from 75.34 to 98.00% and 96.95 to 100.97%, with relative standard deviations of 0.86-4.14 and 1.22-3.52%, in samples treated with and without additional column clean-up procedures, respectively. The minimum detectable amount of imidacloprid was 4 ng, while the limits of detection and quantitation were 0.2 and 0.5 ppm, respectively. The degradation of pesticide was monitored throughout a period of 13 days under greenhouse conditions. Although the behaviors of the EC and WP formulations appear to be similar, the absolute residue levels obtained with EC and WP treatments differed slightly. When imidacloprid formulations were applied (as foliar treatments) according to the recommended rate, the final residues (13 days post-treatment) in Chinese cabbage were much lower than the maximum residue limit (MRL = 3.5 ppm) established by the Korean Food and Drug Administration. Taken together, our study suggests that the analysis of imidacloprid can be performed without an additional column clean-up procedure, and the decline curve and the residue levels in Chinese cabbage could change if the same active ingredient is used in different formulations.