Optical properties of chemical bath deposited CdS thin films

CdS thin films have been prepared by chemical bath deposition. As-deposited films are cubic and show a sulfur deficiency. From the transmittance and reflectance data analysis direct band gaps (E_g) ranging from 2.180 to 2.448 eV have been obtained. Air and vacuum annealed samples show a decrease in the band gap. The refractive index (n) lies in the range 1.61–2.34. A dependence of band gap on composition has been observed and the possible reasons are discussed.     

Functional binding between Gbeta and the LIM domain of Ste5 is required to activate the MEKK Ste11

BACKGROUND: In the budding yeast Saccharomyces cerevisiae, the pheromones that induce haploid cells of opposite cell types to mate activate the Gbeta and Ggamma subunits of a heterotrimeric G protein. These subunits signal through the PAK kinase Ste20 to activate a mitogen-activated protein (MAP) kinase cascade comprising the MEKK Ste11, the MEK Ste7 and two MAP kinases, Fus3 and Kss1. The pathway requires Ste5, a scaffold protein that tethers the MAP kinase cascade enzymes into a high molecular weight complex. Ste5 is thought to associate with Gbeta in a pheromone-independent manner, but it is not known if this interaction affects signaling. RESULTS: A ste5C180A mutant - which expresses Ste5 disrupted in the LIM domain, a putative metal-binding motif that has been proposed to be essential for Ste5 oligomerization - could not transmit the pheromone signal from Gbeta through Ste20 to Ste11. The Ste5C180A protein was impaired in binding Gbeta, although it could oligomerize, bind Ste11, Ste7 and Fus3, facilitate the basal activation of Ste11, and relay the Ste11 signal to MAP kinases. Ste5 bound to Gbeta in a pheromone-dependent manner and preferentially associated with a phosphorylated form of Gbeta in wild-type and ste20Delta, but not in ste5C180A, strains. CONCLUSIONS: Pheromone induces binding of Gbeta to Ste5 through its LIM domain. This binding is essential for activation of Ste11 and is distinct from the ability of Ste5 to oligomerize or to serve as a scaffold and relay the signal from Ste11 to the MAP kinases. Pheromone also induces Ste5-dependent phosphorylation of Gbeta.     

Hybrid Approach to Optimal Packing Using Genetic Algorithm and Coulomb Potential Algorithm

It is difficult and computationally time-consuming to find the best possible solutions for blank packing problems, because they include a lot of underlying combinational conditions. This paper presents two approaches for packing two-dimensional irregular-shaped polygonal elements—a real-encoded genetic algorithm and a hybrid algorithm using a real-encoded genetic algorithm and a local optimization algorithm. The local optimization algorithm presented is a novel one utilizing the Coulomb potential technique.

In the hybrid approach, the real-encoded genetic algorithm generates the order of the polygons while the coulomb potential algorithm determines the embodiment layout under the fixed combinations so as to minimize the scrap. The hybrid genetic algorithm is found to give better results for problems of larger size although it takes more computational time.     

A Genetic-Algorithms-Based Multiobjective Approach for a Three-Dimensional Guillotine Cutting Problem

A novel method based upon multiobjective genetic algorithms is presented for simultaneously minimizing the amount of scrap and the number of turns in a three-dimensional guillotine cutting. The concept of best orientation between two cuboids has been used to improve the efficiency of the minimization process. Two different evolutionary algorithms have been used and also compared for effectiveness.     

A comparative property investigation of lithium phosphate glass melted in microwave and conventional heating

The present study addresses the application of microwave (MW) energy for melting lithium phosphate glass. A comparative analysis of the properties is presented with glasses melted in conventional resistance heating adopting standard methods of characterization. The density of the glass was found less in MW heating. The glass transition temperature was recorded as 3–10\({^{\circ }}\hbox {C}\) lower in MW prepared glass than in conventional glass. Micro-hardness is found to be improved in case of MW heating. Maximum forward power was recorded less than 2 kW with an average power \(\sim \)1 kW during melting of 40 g glass in MW furnace. MW forward and reflected power measured during melting in the MW cavity was elaborated. Total melting time was within 2 h 30 min in MW heating, whereas it was 6–7 h in resistive heating. Total power consumed was \(\sim \)5 kWh in MW heating and \(\sim \)14 kWh in resistance heating.     

In-situ nanoscale Al<Subscript>2</Subscript>O<Subscript>3</Subscript> spherical particle formation in Al-matrix of Al–Si/SiC<Subscript>P</Subscript> MMC foil by laser pulsing

An excimer pulse laser treatment is gaining more popularity for the surface modification of a metallic material due to its non-equilibrium processing character, ease of process, minimal depth of modification, effective absorptivity and extremely high cooling rate. In the present study, the laser surface treatment of the Al–Si/SiC_P Metal Matrix Composite foil was carried out by pulse excimer laser. The parameter used for the surface modifications are: pulse energy 1980 J m^–2 and number of pulses 1, 5 and 10. The microstructural characterization was carried out by SEM and TEM (Transmission Electron Microscopy), whereas the compositional analysis was done by TEM/EDS (Energy dispersive spectroscopy). The work demonstrates the possibility of in situ formation of fine scale, nano- to sub-micrometer, Al₂O₃ particles in the surface layer of Al-matrix composite. After a pulse of laser is irradiated on the Metal Matrix Composite surface, spherical Al₂O₃ particles are observed to nucleate and grow heterogeneously, whereas after 5 pulses of laser treatment, the fraction of Al₂O₃ particles increased. Later, at 10 pulses, it further increases ~30% of the surface. The particles showed a size distribution, the higher size limit increase with number of pulses, but it remains same around (2–20 nm) for lower range. Transmission Electron Microscopy study indicates the nucleation of the new Al₂O₃ phase with laser pulse cycle concurrent with the growth of the already existing particles.     

Batch biodegradation of PAHs in mixture by Mycobacterium frederiksbergense: analysis of main and interaction effects

Biodegradation is an effective technique to remediate soil and water contaminated with polycyclic aromatic hydrocarbons (PAHs). In the present experimental study, Mycobacterium frederiksbergense, a fast growing mycobacterium, was used to degrade anthracene, naphthalene and pyrene in mixture each at initial concentrations varying between 1 and 50 mg l⁻¹. Experiments were conducted according to the 2³ factorial design at the low (1 mg l⁻¹) and high (50 mg l⁻¹) levels of the PAHs in combination, to identify the main and interaction effects of the compounds on their biodegradation. The results showed that the PAH removals varied 54–81% when each PAHs were at low concentrations in the mixture and 67–89% at their higher concentration combinations. Statistical analysis of the results in the form of ANOVA and Student t test indicated significant role played by the main effects of pyrene on its degradation. Similarly on anthracene degradation, interaction effect with pyrene was found to be highly significant with P value less than 0.1.     

Experimental and finite element studies on mode I and mixed mode (I and II) stable crack growth—II. finite element analysis

Finite element studies are presented on both mode I and mixed mode stable crack growth under static loadings through an aluminium (D16AT) alloy. A COD based criterion has been used to predict the load-displacement diagram from initiation to instability. The theoretical predictions are compared with experimental results presented in Part I. Results on computed crack profiles, stress-strain distribution ahead of the crack tip, J integrals, J resistance curves, plastic zones, etc., are included. The study indicates that the load-displacement diagram associated with a mixed mode stable crack growth in a compact tension type of specimen geometry can be predicted reasonably accurately using the criterion of a fixed crack opening displacement at a finite distance behind the crack tip provided the crack is allowed to grow in the direction of initial growth in the finite element analysis. The crack assumes a more blunted profile in a mixed mode than in the mode I at all the stages of stable extension. The distributions of normal stress and strain in the direction perpendicular to the crack extension line, ahead of the current crack tip, have similarities between the mode I and mixed mode, irrespective of loading angle. Both the stress and strain levels increase as the crack extension proceeds. In a mixed mode, the J integral at the onset of crack extension is the lowest compared with the values at the later stages of the extension. Further, the tearing modulus associated with initial kinking is very small; it becomes close to the mode I values at the later stages. The tearing modulus remained approximately constant during the whole mode I stable growth and it had a similar trend subsequent to kinking in a mixed mode. The specific work of crack extension is zero as Δa → 0 and it increases gradually with Δa irrespective of the mode of loading; the actual variation depends on the loading angle. The plastic zone size grows as the stable extension progresses; the growth is approximately the maximum along the crack extension line.