Application of a genetic algorithm to optimal lay-up of shells made of composite laminates

The orientation of fiber direction in layers and the number of layers of composites play the major role in determining the strength and stiffness. Thus, the basic design problem is to determine the optimum stacking sequence of the composite laminate. Many methods are available at present for the design optimization of structural systems. However, these methods are based on mathematical programming techniques involving the gradient search and the direct search. These methods assume that the variables are continuous. In this paper, a different search and optimization algorithm, known as a Genetic Algorithm (GA), has been successfully applied to obtain the optimum fiber orientation of multilayered shells, which considers the angle of fiber orientation as a discrete variable. The principle of GA is applied to obtain optimum layers and the orientation of fibers of stiffened shells for both the symmetric and antisymmetric orientations of fibers for dynamic analysis. Shells composed of two to nine layers without stiffeners, with one stiffener, and with two stiffeners for a single as well as different materials are analyzed and the maximum frequency for each population is computed using the FEAST-C software. Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000). Published in Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 271–278, March–April, 2000.     

Sensing of Pyrophosphate Anion by a Fluorescent Zn(II) Complex Bearing Acenaphthene Imidazole Moiety

Journal of Analytical Chemistry - Acenaphthene imidazole ligand (AIMP) reacted with zinc acetate for the synthesis of Zn-AIMP complex which was used to detect pyrophosphate (PPi) ions in the...     

A microscopic study on shape transition and shape coexistence in superdeformed nuclei

Superdeformed nuclei at high-spin states in several mass regions are investigated within a microscopic approach using cranked Nilsson-Strutinsky formalism to explore the equilibrium deformations in the ground state and their evolution with spin. Shape transition from normal deformed to superdeformed states with increasing spin is studied and a clear picture of shape coexistence is provided. Detailed information on spin, rotational energy, dynamical moment of inertia, and rotational frequency of superdeformed rotational bands is presented and the general features of superdeformed bands in certain mass regions are outlined. Rotational energy and dynamical moment of inertia are compared with available experimental data and the impact of temperature and pairing on superdeformed configuration are discussed.     

Crystal structure,dielectric properties of (K0.5Na0.5)NbO3 single crystal grown by flux method using B2O3 flux

Lead free piezoelectric single crystals of sodium potassium niobate (K_0.5Na_0.5)NbO₃ (KNN) were grown by high‐temperature solution method using two different fluxes; one with a mixture of NaF and KF and other with addition of B₂O₃ along with the mixture. In the present study, the growth of KNN crystals without B₂O₃ flux and the same with B₂O₃ flux were compared. It was found that additions of small amounts of B₂O₃ lowered the melting temperature of the solid solution and enabled better dielectric properties. Phase analysis showed that all samples were crystallized in pure orthorhombic perovskite phase. AFM morphological studies showed that the addition of B₂O₃ flux increased the roughness of the grown crystal. Further, addition of B₂O₃ flux slightly decreased the orthorhombic to tetragonal phase transition temperature T_(O—T) and the Curie temperature T_C. The ferroelectric behaviour of KNN single crystal has been investigated at room temperature. The crystal grown using B₂O₃ flux exhibited a remanent polarization (P_r) ∼ 32 μC/cm² and coercive field (Ec) of ∼11.8 kV/cm whereas the crystal grown without the use of B₂O₃ flux had a remanent polarization (P_r) ∼ 36 μC/cm² and coercive field (Ec) of ∼14.6 kV/cm.     

Growth and characterization of semiorganic crystal

Single crystals of urea thiourea sodium chloride (UTNC) were grown from aqueous solution by slow evaporation technique. FTIR spectra were recorded to identify the functional groups. The crystals were characterized by recording the powder X-ray diffraction that revealed the crystalline nature of the crystal. The UV?CVis spectral study was carried out to test the optical transmitting property. The second harmonic generation test (SHG) was carried out, and it shows the non-linear nature of the crystal. The thermal stability of the crystal was analyzed by thermogravimetric and differential thermal analysis (TG-DTA).     

Photo-pens: a simple and versatile tool for maskless photolithography

We demonstrate conical pores etched in tracked glass chips for fabricating patterns at the micrometer scale. Highly fluorescent patterns based on photopolymerization of diacetylene films were formed by irradiating UV light through conical pores called "photo-pens". The properties of photopens were investigated through experiments, finite-difference-time-domain (FDTD) simulations and numerical calculations based on Fresnel equations. We show that the pattern dimensions are easily controlled by adjusting the exposure time. Thus, patterns with a range of dimensions can be fabricated without any need of changes in the pore diameter. Parallel patterning was also demonstrated by simultaneously exposing the films to photons through multiple pores in the chip. Our method provides an inexpensive, versatile, and efficient way for patterning without the use of sophisticated masks.     

Vanadium(V)-substituted Keggin-type heteropolyoxotungstophosphates as electron transfer and antimicrobial agents: oxidation of glutathione and sensitization of MRSA towards β-lactam antibiotics

Glutathione (GSH) undergoes facile electron transfer with vanadium(V)-substituted Keggin-type heteropolyoxometalates, [ \textPV^\textV \textW _{1 1} \textO _{4 0} ] ^{4 -} [ {\text{PV}}^{\text{V}} {\text{W}}_{ 1 1} {\text{O}}_{ 4 0} ]^{{ 4 { - }}} (HPA1) and [ \textPV^\textV \textV^\textV \textW _{1 0} \textO _{4 0} ] ^{5 -} [ {\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} ]^{{ 5 { - }}} (HPA2). The kinetics of these reactions have been investigated in phthalate buffers spectrophotometrically at 25 °C in aqueous medium. One mole of HPA1 consumes one mole of GSH and the product is the one-electron reduced heteropoly blue, [ \textPV^\textIV \textW _{1 1} \textO ₄₀ ] ^5- [ {\text{PV}}^{\text{IV}} {\text{W}}_{ 1 1} {\text{O}}_{ 40} ]^{ 5- } . But in the GSH-HPA2 reaction, one mole of HPA2 consumes two moles of GSH and gives the two-electron reduced heteropoly blue [ \textPV^\textIV \textV^\textIV \textW ₁₀ \textO ₄₀ ] ^7- [ {\text{PV}}^{\text{IV}} {\text{V}}^{\text{IV}} {\text{W}}_{ 10} {\text{O}}_{ 40} ]^{ 7- } . Both reactions show overall third-order kinetics. At constant pH, the order with respect to both [HPA] species is one and order with respect to [GSH] is two. At constant [GSH], the rate shows inverse dependence on [H⁺], suggesting participation of the deprotonated thiol group of GSH in the reaction. A suitable mechanism has been proposed and a rate law for the title reaction is derived. The antimicrobial activities of HPA1, HPA2 and [ \textPV^\textV \textV^\textV \textV^\textV \textW ₉ \textO _{4 0} ] ^{6 -} [ {\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 9} {\text{O}}_{ 4 0} ]^{{ 6 { - }}} (HPA3) against MRSA were tested in vitro in combination with vancomycin and penicillin G. The HPAs sensitize MRSA towards penicillin G.     

Biological evaluation of redox stable cisplatin/Cu(II)-DNA adducts as potential anticancer agents

A series of non-enolizable β-diketonate-based copper(II) complexes with LCuCl₂ [L = Knoevenagel condensates of curcumin (Salcimine) and methylacetoacetate (SalMaA)-based Schiff bases] chromospheres as functional models of chemotherapy drug cisplatin were investigated for their covalent interaction with herring sperm DNA. The synthesis and structural characterization of 1a and 1b have been reported in our previous article. However, their DNA interactions and cytotoxicity properties were not studied. These analyses have been carried out mainly through electrochemical techniques supplemented with spectral, relative viscosity, gel electrophoresis techniques, and AGS cancer cells using MTT assay. The cytotoxic activities of the ligand, curcumin-based copper complex, and cisplatin were tested against the AGS cancer cell line under similar experimental conditions showing that the complex exhibited cancer cell inhibitory rate closer to cisplatin even at low concentration. This was also seen in the docking of the Cu-complex onto a rich guanine B-DNA decamer, where a Cu–N3_(guanine) interaction instead of Pt-N7 as cisplatin is detected. The obtained results in this study prove that these complexes could be a promising substitute for cisplatin as a new family of non-platinum-based anticancer metallo-drugs after in vivo tests on animal models.     

Analysis of curved beams using a new differential transformation based curved beam element

Differential transformation method is used to obtain the shape functions for nodal variables of an arbitrarily non-uniform curved beam element including the effects of shear deformation considering axially functionally graded material. The proposed shape functions depend on the variations in cross-sectional area, moment of inertia, curvature and material properties along the axis of the curved beam element. The static and free vibration of axially functionally graded tapered curved beams including shear deformation and rotary inertia are studied through solving several examples. Numerical results are presented for circular, parabolic, catenary, elliptic and sinusoidal beams (both forms—prime and quadratic) with hinged-hinged, hinged-clamped and clamped-clamped and clamped-free end restraints. Three general taper types (depth taper, breadth taper and square taper) for rectangular cross section are studied. Out of plane vibration is studied and the lowest natural frequencies are calculated and compared with the published results. Out of plane buckling is investigated for circular beams due to radial load.