A study of effects of wall-normal rotation on the turbulent channel flow

The effects of the wall–normal rotation on the turbulence channel flow have been studied. A series of direct numerical simulations have been performed with various rotation rates for Reynolds number 180 based on the friction velocity in the non–rotating case. All remarkable changes are discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Anodic electrodeposition of Ag1− x Cu x O microcrystals

We demonstrate the anodic electrodeposition of copper-doped AgO at high pH using a silver counter-electrode. Precipitates from a mixture of nitrates and NaOH provided source material for the deposition, and application of a moderate anodic voltage (0.9 V) to the substrate led to deposition of crystalline nanoparticles with incorporated copper. Further increase of the NaOH concentration reduced the amount of copper in the crystals, and higher voltages degraded the crystal quality. XRD confirms the underlying structure to be that of AgO, and Auger and energy dispersive x-ray analyses confirm copper concentrations of approximately 3 % in the crystals.     

A novel technique based on diffuse reflectance near-infrared spectrometry and back-propagation artificial neural network for estimation of particle size in TiO2 nano particle samples

Determination of particle size is one of the critical parameters in nanotechnology. The relationship between particle size and diffuse reflectance (DR) spectra in near-infrared region has been applied to introduce a method for estimation of particle size. Back-propagation artificial neural network (BP-ANN) as a nonlinear model was applied to estimate average particle size based on near-infrared diffuse reflectance spectra. Thirty five different nano TiO₂ samples with different particle size were analyzed by DR-FTNIR spectrometry and the obtained data were processed by BP-ANN. The network was trained by 30 samples and was evaluated by the remaining 5 samples. In order to establish whether the new method is applicable for estimation of particle size of nano structured samples, the optimized model was applied to analyze 44 nano TiO₂ samples. It was observed that ANN using the back-propagation algorithm is capable of generalization and could correctly predict the average particle size of nano-sized particles.     

Rapid and Highly Sensitive Detection of Target DNA Related to COVID-19 Virus With a Fluorescent Bio-conjugated Probe via a FRET Mechanism

Journal of Fluorescence - A novel cyanine 3 (Cy3)-based bio-conjugated sensor has been developed to detect target DNA or extracted RNA from COVID -19 samples using the fluorescence resonance energy...     

Hydrophobin purification based on the theory of CO2-nanobubbles

Purification is a critical step to obtain hydrophobin HFBII for use in positive applications. In this study, hydrophobin HFBII was produced by Trichoderma reesei via submerged fermentation. Using the CO₂-foam fractionation method yielded a fourfold increase in protein concentration. The foamate (α_L-HFBII) was dried using a nano spray-dryer under optimal temperature. The gushing activity of the dried foamate (α_S-HFBII) decreased. Addition of Tween 80 to the foamate before the drying process partially prevented the deactivation of hydrophobin HFBII. The purity of the powder was enhanced based on the theory of CO₂-nanobubbles in a CO₂-rich environment. The collected CO₂-nanobubbles were added to an apolar–polar system and the interface of these two phases was collected. After evaporation of the apolar phase, the purity of the hydrophobins assembled on the surface of the liquid was significantly improved.     

Application of QR Decomposition Algorithm for Multivariate Calibration in High Overlapping Systems

An accurate and stable algorithm, QR Decomposition Algorithm (QRDA) is initially presented into the chemistry field. The basic principle of QR Multivariate Calibration Algorithm (QRMCA) is investigated, and the complexes system of sodium tripolyphosphate (STPP), sodium sulfate (SS), and sodium Carbonate (SC) with serious overlapping absorption peaks is analyzed by QRMCA. According to our survey, QRDA can avoid matrix inverting, reduce the orders of matrixes, and speed up the operation of matrices. So, it has bright prospects in chemometrics. The process of the QR Decomposition Algorithm (QRDA) was implemented by an orthogonal and upper triangular matrix decomposition that is robust and convenient. Then it was applied to overcome the problem of overlapping spectra of different components in detergent-washing powder.     

Direct syntheses,characterization and optical analysis of PbX2 (X = I,Br and Cl) nanoparticles without any additives

Lead iodide, bromide and chloride nanoparticles (NP-PbX₂, X = I, Br and Cl) with various morphologies were successfully prepared through a simple hydrothermal method without any additives or stabilizers. By treating the PbX₂ in EtOH/CH₂Cl₂ solution at 170 °C for 12 h, the corresponding PbX₂ nanoparticles were synthesized. The average sizes of PbX₂ nanoparticles were between 30 and 80 nm. The structure, morphology, surface and size of PbX₂ nanoparticles were determined by X-ray diffraction powder, Scanning Electron Microscopy, solid state Photo Luminescent, BET surface area and solid state UV.     

Characterization of a cylindrical rod by inversion of acoustic scattering data

In this paper, a new approach is proposed for nondestructive characterization of immersed and embedded isotropic rod-shaped samples by inversion of acoustic scattering data. The normal mode expansion technique is used for modelling the scattered field and the compression incident and compression scattered waves are considered. Genetic algorithm is the inversion technique used for estimating the elastic wave velocities and density of the rods from their measured backscattered pressure spectrum. The inversion technique is capable of computing the parameter values that best fit a particular set of data. A perturbation study is conducted on the sensitivity of the resonance frequencies to changes in elastic properties and density of the rods. The numerical results indicate that proper selection of resonance frequencies leads to accurate measurement of elastic constants and density. The proposed approach showed very good convergence and the results obtained were found to agree very well with available data.     

Reward maximization in general dynamic matching systems

Queueing Systems - We consider a matching system with random arrivals of items of different types. The items wait in queues—one per item type—until they are “matched.” Each...