Conformal Ricci Collineations of Static Spherically Symmetric Spacetimes

Conformal Ricei collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating eonformal Rieei eollineations is found when the Rieei tensor is non-degenerate, in which ease the number of independent eonformal Rieei eollineations is 15, the maximum number for four-dimensional manifolds. In the degenerate ease it is found that the static spherically symmetric spaeetimes always have an infinite number of eonformal Rieei eollineations. Some examples are provided which admit non-trivial eonformal Rieei eollineations, and perfect fluid source of the matter.     

An improved Darcian analysis for chemically reacted Maxwell liquid toward convectively heated moving surface with magnetohydrodynamics

Journal of Thermal Analysis and Calorimetry - Heat transportation analysis subjected to porous medium consideration has increased because of industrial and engineering utilization. Typical examples...     

Carter's fourth invariant of the motion

An interpretation of Carter's fourth invariant of the motion is presented and its significance is discussed.     

Simultaneous spectrophotometric determination of nitrite and nitrate by flow injection analysis.

A new catalytic spectrophotometric method is reported for the simultaneous determination of nitrite and nitrate by flow injection analysis, based on the catalytic effect of nitrite on the redox reaction between pyrogallolsulfonephthalein and potassium bromate in acidic media. Nitrate can also be on-line reduced to nitrite with a modified copper-coated cadmium reduction column. The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of pyrogallolsulfonephthalein at 465 nm. Various analytical parameters such as effects of acidity, reagent concentrations, flow rates, sample sizes, lengths of the reaction coil and temperatures were studied and were optimized. Under the optimized conditions, the calibration graph was linear for 2.4 to 160 ng ml(-1) of nitrite and 4.0 to 100 ng ml(-1) of nitrate. The influences of potential interfering cations and anions for nitrite and nitrate determination were studied. The method is successfully applied for food and water samples. Up to ten samples can be analyzed per hour.     

Modeling Thin Film Multilayer Broad-Band-Pass Filters in Visible Spectrum

Multilayer thin-film structures have been used to model and analyze the performance of broad-band-pass interference optical filters in visible spectrum. Starting from nine-layer configuration comprising quarter-wave layers, the number of layers is increased to make the pass band smooth with steep slopes and square band-pass characteristics. The layer materials are also varied to improve the performance of the filters. Further, matching layers are also introduced with incident medium and the substrate to reduce the magnitude of ripples in the pass band. Shift in the peak wavelength is also investigated as a function of angle of incidence.     

A mathematical model for the study of gliding motion of bacteria on a layer of non‐Newtonian slime

This paper is concerned with a mathematical hydrodynamical model of motility involving an undulating cell surface. The cell surface transmits stresses through a layer of exuded slime to the substratum. The slime is considered as a Johnson–Segalman fluid. A perturbation approach is used to find the analytic solution. Analytical expressions for the stream function, velocity, pressure gradient and pressure rise over a wavelength as well as the corresponding computational results are presented. The propulsive and lift forces and the power required for gliding propulsion have also been determined. The presented mechanism is found to generate a force for the propulsion of glider at a realistic speed and requires an output of power that is much less than the organism's metabolic rate of energy production. It is observed that unlike the Newtonian case of slime, the lift force is generated due to the Weissenberg number for non‐Newtonian slime, represented by the model of Johnson–Segalman fluid. It is also found that power required for translation in Johnson–Segalman fluid is reduced. Copyright © 2004 John Wiley & Sons, Ltd.     

Radiolabeling of anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb BW 431/26) for clinical applications

A method for labeling of anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb) BW 431/26 is described. For preparations of^99mTc-anti-CEA complex, a solution (1 ml) of tetrasodium-1,1,3,3-propanetetetraphosphate dihydrate (2.7 mg), stannous chloride dihydrate (0.12 mg) and sodium chloride (0.2 mg) in 5 ml of 0.9% saline was added to a vial containing monoclonal antibody (2 mg) from mouse (MAb BW 431/26), D-glucitol (2 mg) and sodium sulfate (2 mg) to obtain a clear solution. A quantitative labeling yield of the MAb BW 431/26 was achieved by addition of 5 ml (40.5 mCi, 1.5 Gbq) technetium-99m-pertechnetate (^99mTcO₄) generator eluate at room temperature within 10 minutes. The radiochemical purity determined by ITLC (Gelman, SG) plates was >95%.     

A comparative study to evaluate the performance of coated Fe3O4 nanoparticles for adsorption of asphaltene from crude oil in bench scale

The present study was conducted to evaluate the performance of magnetic Fe₃O₄ nanoparticles coated with polythiophene (PT), Mil-101 (Cr) (MOF), graphene oxide (GO), SiO₂, and chitosan for adsorption of asphaltene from crude oil in a bench scale setup. All nanoparticles were synthesized using co-precipitation method. The characteristics of nanoparticles were verified using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and field emission scanning electron microscope (FESEM) analyses. The concentration of nanoparticles was kept constant at the optimum value of 10g?L^?1. The amount of asphaltene adsorption was determined at different contact times of 0.5, 0.75, 1, 2, and 4 hours. The results showed that the adsorption increased with contact time and reached equilibrium after about 2 hours in both continuous and batch experiments. The amount of asphaltene adsorption was lower in continuous experiments compared to batch experiments. However, it was found that magnetic nanoparticles are applicable for inhibition of asphaltene precipitation under flow conditions. Furthermore, polythiophene coating on magnetic Fe₃O₄ nanoparticles had the highest capacity for asphaltene adsorption. Besides, by applying a magnetic field, the magnetic nanoparticles that adsorbed asphaltene can be separated from crude oil to prevent asphaltene aggregation and precipitation.     

Triethylammonium picrate: An above-room-temperature phase transition material to switch quadratic nonlinear optical properties

Quadratic nonlinear optical properties of the picrate-based molecular crystal have been switched using the order-disorder phase transition, which opens up a potential way to design stimuli-responsive materials.     

Hydrogen evolution reaction and formic acid oxidation by decorated nanostructural Pt/Pd on a copper-filled nanoporous stainless steel

In this work, a 304 stainless steel (SS) was anodized to prepare nanoporous SS (NPSS) with an average size of about 75 nm and then filled with copper (Cu/NPSS) using pulsed electrodeposition method. Afterward, a nanostructural Pt and Pd film was deposited by galvanic replacement (GR) on the Cu/NPSS to prepare modified electrode (PtPd/Cu/NPSS) for hydrogen evolution reaction (HER) and formic acid electrooxidation (FAO). The electrocatalytic activity of the modified electrode and its structural characterization have been studied by voltammetric methods, electrochemical impedance spectroscopy (EIS), inductively coupled plasma optical emission spectrometry (ICP-OES), and field emission scanning electron microscopy (FESEM). The results show that the nanostructural Pt₁Pd₁/Cu/NPSS composition, with low Pt loading and suitable stability, has a good electrocatalytic performance toward HER (E_Onset = + 12 mV vs. NHE) and FAO (E_Onset = ?180 mV vs. NHE). For HER observed a high mass activity of noble metals (87.54 mA cm^?2μg _Pd+Pt ^?1 ) in comparison with Pt deposited Cu/NPSS (41.5 mA cm^?2 μg _Pt ^?1 ) at the same applied potential of ? 0.25 V versus NHE. Also, the fabricated electrocatalysts with more electrochemically active surface area in comparison with Pd/Cu/NPSS and Pt/Cu/NPSS revealed more resisting to the poisoning components and good stability for FAO.