Iteratively reweighted least squares and slime mold dynamics: connection and convergence

Mathematical Programming - We present a connection between two dynamical systems arising in entirely different contexts: the Iteratively Reweighted Least Squares (IRLS) algorithm used in compressed...     

Effect of macropore convection on mass transfer in a bidisperse adsorbent particle

The importance of adsorption induced convection in the macropores of a bidisperse adsorbent particle is studied for a step change in mole fraction or total pressure at the surface of the particle. Material balance equations for a binary gas mixture are written for both the macropores and the macropores with allowance for convection in the macropores, which is described by Darcy's law. The coupled set o1' partial differential equations is solved by orthogonal collocation. The enhancement in mass transfer as a result of convection is assessed by comparing the fractional uptake curves obtained with and without allowance for convection. Both equilibrium-based and kinetic-based separation processes are considered. The effect of the presence of convection in determining the controlling diffusional resistance (macropore or micropore) is also examined. Due to inclusion of convection no single non-dimensional group alone can determine the relative importance of macropore and micropore resistances. Results show that convection can significantly affect the performance of an equilibrium-based macropore diffusion controlled process and that the enhancement in mass transfer is more for a particle with a high value of Darcy permeability.     

rmpM Genosensor for Detection of Human Brain Bacterial Meningitis in Cerebrospinal Fluid

Human brain bacterial meningitis is a life-threatening disease caused mainly by Neisseria meningitidis, lead to damage of the outer membrane covering (meninges) of brain or even death. The usual methods of diagnosis are either time-consuming or have some limitations. The specific rmpM (reduction-modifiable protein M) virulent gene based genosensor is more sensitive, specific, and can detect N. meningitidis directly from the patient cerebrospinal fluid in 30 min including 1-min response time. 5′-Thiol-labeled single-stranded DNA (ssDNA) probe was immobilized onto screen-printed gold electrode (SPGE) and hybridized with denatured (95 °C) single-stranded genomic DNA (ssG-DNA) for 10 min at 25 °C. The electrochemical response was measured by cyclic voltammetry, differential pulse voltammetry (DPV) and electrochemical impedance using redox indicators. The sensitivity of the genosensor was 9.5087?(μA/cm²)/ng with DPV and limit of detection was 3 ng/6 μL ssG-DNA. The immobilization of the ssDNA probe and hybridization with ssG-DNA from N. meningitidis was characterized by atomic force microscopy and Fourier transform infrared spectroscopy. The rmpM genosensor was stable for 6 months at 4 °C with 10 % loss in initial DPV current. The advantage of rmpM genosensor is to detect bacterial meningitis simultaneously in multiple patients using SPGE array during an outbreak of the disease.     

Design and synthesis of organochalcogen (Se or Te) based multifunctional derivatives: structural determination and dynamic behavior of 2-chloro-4,6-bis(phenylselenoethylamino)-1,3,5-triazines

A novel class of multifunctional and multinucleate chalcogen (selenium and tellurium) containing derivatives (1-10) has been developed based on sequential chloride substitution of 2,4,6-trichloro-1,3,5-triazine with chalcogen-bearing amines. The structure of compound 1 has been determined in the solid state by X-ray crystallography.     

Influence of the Oxide Content in the Catalytic Power of Raney Nickel in Hydrogen Generation

The influence of oxides in the hydrogen evolution on Raney nickel electrocatalysts was characterized by electrochemical impedance measurements. In addition, these materials show competitive overpotentials for hydrogen evolution with a modified Watts bath as a binder for the Raney nickel. The optimum result was ?190?mV of overpotential at 100?mA?cm^?2. Oxygen in the Raney Ni catalyst affects its electroactivity toward hydrogen evolution. The source of oxygen is related to the presence of chloride ions in the modified Watts bath. A Watts bath binds Raney Ni particles to the surface of the catalysts and chloride regulates the oxygen content in the nickel binder during electrodeposition. High oxygen content increases the hydrogen evolution overpotential of the electrode. The electroactivity of the synthesized porous coatings was evaluated by polarization curves and impedance plots. In addition, surface characterization by X-ray diffraction, field emission–scanning electron microscopy equipped with energy-dispersive analysis, and X-ray photoelectron spectroscopy is reported.     

Biocompatibility of gold nanoparticles and their endocytotic fate inside the cellular compartment: a microscopic overview

Macrophages are one of the principal immune effector cells that play essential roles as secretory, phagocytic, and antigen-presenting cells in the immune system. In this study, we address the issue of cytotoxicity and immunogenic effects of gold nanoparticles on RAW264.7 macrophage cells. The cytotoxicity of gold nanoparticles has been correlated with a detailed study of their endocytotic uptake using various microscopy tools such as atomic force microscopy (AFM), confocal-laser-scanning microscopy (CFLSM), and transmission electron microscopy (TEM). Our findings suggest that Au(0) nanoparticles are not cytotoxic, reduce the production of reactive oxygen and nitrite species, and do not elicit secretion of proinflammatory cytokines TNF-alpha and IL1-beta, making them suitable candidates for nanomedicine. AFM measurements suggest that gold nanoparticles are internalized inside the cell via a mechanism involving pinocytosis, while CFLSM and TEM studies indicate their internalization in lysosomal bodies arranged in perinuclear fashion. Our studies thus underline the noncytotoxic, nonimmunogenic, and biocompatible properties of gold nanoparticles with the potential for application in nanoimmunology, nanomedicine, and nanobiotechnology.     

XANES of the AuLIII edge in gold metal and in two compounds AuCN and AuCl3

The X-ray Absorption Near Edge Structure (XANES) of the AuL_III edge in gold metal and in its two compounds AuCN and AuCl₃ have been recorded. The observed chemical shifts of the edge and the fine structure peaks in the compounds are discussed. It is observed that the energy shifts ΔE of the AuL_III due to chemical effects in aurous cyanide (AuCN) and auric chloride (AuCl₃) with respect to the pure Au edge is 2.9 eV in AuCN and 0.7eV in AuCl₃. The edge widths in AuCN and AuCl₃ are found to be almost the same for both the compounds, presumably because electronegativities of CN and Cl are not very different. The observed fine structure peaks of the discontinuities of AuCN and AuCl₃ are displaced progressively away from the main edge.