Generalized {G_\delta}-submaximal spaces

We study some properties of generalized submaximal spaces and introduce the notion of generalized door spaces. Furthermore we extend these notions to generalized \({G_\delta}\)-submaximal spaces by replacing \({\mu}\)-open sets by \({\mu-G_\delta}\)-sets and consider some of their properties.     

Synthesis and characterization of new fluorinated photoactive polyamides based on xanthene pendant: Evaluation of antibacterial and heavy metal ions removal behavior

A series of novel organosoluble polyamides (PAs) bearing different functional groups such as flexible ether, substituted imidazole, and xanthene rings and electron-withdrawing CF₃ groups were synthesized from diamines and various dicarboxylic acids. The structures of diamines and PAs were fully characterized by elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The PAs showed good solubility in aprotic and polar organic solvents, with high thermal stability exhibiting the glass transition temperatures (T_gs) and 10% weight loss temperatures (T₁₀%) in the range of 184–277°C and 410–480°C in N₂ atmosphere, respectively. These polymers showed fluorescence emission upon irradiation with UV light. Diamine compounds and two of synthesized polymers were also screened for antibacterial activity against gram-positive and gram-negative bacteria, and the obtained results for all four combinations showed good inhibition. Extraction capability for heavy metal ions such as Cr³⁺, Pb²⁺, Hg²⁺, Cd²⁺, and Co²⁺ from aqueous solutions was also tested at 25°C and pH 7–8.     

Optimization by Response Surface Methodology of the Adsorption of Anionic Dye on Superparamagnetic Clay/Maghemite Nanocomposite

Russian Journal of Applied Chemistry - Magnetic nanoparticles and clay minerals combine to form a class of advanced nanocomposites that would possess exceptional adsorption, magnetism, and...     

Green synthesis of silver nanoparticles using Eucalyptus comadulensis leaves extract and its immobilization on magnetic nanocomposite (GO-Fe3O4/PAA/Ag) as a recoverable catalyst for degradation of organic dyes in water

The magnetically recyclable graphene oxide-Fe₃O₄/polyallylamine (PAA)/Ag nanocatalyst was prepared via a green route using Eucalyptus comadulensis leaves extract as both reducing and stabilizing agent. The catalytic activity of this nanocatalyst was investigated for the reduction reaction of methylene blue and methyl orange in the presence of NaBH₄ in aqueous medium at room temperature. The prepared nanocatalyst was characterized by different methods such as Fourier transformed infrared spectroscopy, X-ray diffraction, scanning electron microscopy–energy dispersive X–ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, transmission electron microscopy, and UV–visible spectroscopy. The results show that graphene oxide/PAA/Ag nanocatalyst has good activity and recyclability, and can be reused several times without major loss of activity in the reduction process. The apparent rate constants of the methyl orange (MO) and methylene blue (MB) were calculated to be 0.077 s⁻¹ (3 mg of catalyst) and 0.15 s⁻¹ (2 mg of catalyst), respectively.     

Effect of geometric nonlinearity on dynamic pull-in behavior of coupled-domain microstructures based on classical and shear deformation plate theories

This paper investigates the dynamic pull-in behavior of microplates actuated by a suddenly applied electrostatic force. Electrostatic, elastic and fluid domains are involved in modeling. First-order shear deformation plate theory and classical plate theory are used to model the geometrically nonlinear microplates. The equations of motion are descritized by the finite element method. The effects of nonlinearity, fluid pressure, initial stress and different geometric parameters on dynamic behavior are examined. In addition, the influences of initial stress and actuation voltage on oscillatory behavior of microplates are evaluated.     

Glucose Biosensor Based on Silicon Nitride Nanoparticles

For the first time silicon nitride (Si₃N₄) nanoparticles was used for preparation electrochemical biosensor. GOx immobilized on the Si₃N₄ nanoparticles exhibits facile and direct electrochemistry. The surface coverage and heterogeneous electron transfer rate constant (k_s) of immobilized GOx were 6.3×10^?13 mol cm^?2 and 47.4±0.3 s^?1. The sensitivity, linear concentration range and detection limit of the biosensor for glucose detection were 38.57 µA mM^?1 cm^?2, 25 µM to 8 mM and 6.5 µM, respectively. This biosensor also exhibits good stability, reproducibility and long life time. These indicate Si₃N₄ nanoparticles is good candidate material for construction of third generation biosensor and bioelectronics devices.     

Static pull-in analysis of electrostatically actuated microbeams using homotopy perturbation method

In this study, static pull-in instability of electrostatically-actuated microbridges and microcantilevers is investigated considering different nonlinear effects. Galerkin’s decomposition method is utilized to convert the nonlinear differential equations of motion to nonlinear integro-algebraic equations. Afterward, analytic solutions to static deflections of the microbeams are obtained using the homotopy perturbation method. Results are in excellent agreement with those presented in the literature.     

Studies in molecular structure,symmetry and conformation I

Crystals of 1-aminocyclooctanecarboxylic acid hydrobromide are orthorhombic, witha= 26·026,b=7·087,c= 6·149,Z= 4 and space groupP2₁2₁2₁.The structure was solved in projections by direct methods and later refined with three-dimensional data using a full-matrix least-squares treatment. All hydrogen atoms were located from a difference Fourier and the finalRfactor for the 1128 observed reflections was 8·62 %. The molecules are held together by a series of hydrogen bonds in a three-dimensional network. A detailed discussion of the intramolecular and the intermolecular features of the structure is presented. The cyclooctane ring is found to exist in theboat-chair conformation.Contribution No. 304 from the Centre of Advanced Study in Physics, University of Madras, Madras-25, India.Our thanks are due to Dr K. Venkatesan for valuable discussions and to Professor G. N. Ramachandran for his keen interest. The refinement of the structure was carried out at first using the G. A. Mair's program for IBM 1620 and later using the full-matrix least-squares program (Program LALS) of Gantzel, Sparks and Trueblood, modified by Braenden, Zalkin and by Lundgren and Liminga in Uppsala for CDC 3690. The authors would like to record their thanks to these individuals for making their programs available. Thanks are due also to the authorities of the Tata Institute of Fundamental Research, Bombay and the Fundamental Engineering Research Establishment, Madras for making available computer facilities. One of us (T.S.) is grateful to the University of Madras and the Council of Scientific and Industrial Research, India for financial assistance. This work was supported in part by a grant to R. Zand from the National Institute of Neurological Diseases and Stroke, National Institutes of Health.