Effects of IR Laser Shots on the Surface Hardness and Electrical Resistivity of High-Purity Iron

Annealed specimens of 99.99% pure iron were irradiated with 500, 750, 1000, and 1250 Nd:YAG laser shots. The laser fluence and laser intensity at the laser irradiation spot on the target surface were 4.4 × 10³ J/cm² and 4.8 × 10¹¹ W/cm², respectively. Vickers hardness of irradiated specimens was measured at various points separated by 0.5 mm in four different mutually perpendicular directions around the laser irradiation spot. The surface hardness profile for each irradiated specimen shows an increasing trend in surface hardness till a distance of 3.5 mm from the reference point. The average surface hardness (ASH) is found to increase up to 21% and electrical resistivity increases up to 50% as the number of laser shots is increased to 1250. A linear relationship between electrical resistivity and ASH is observed. Moreover, the ASH follows the well-known Hall-Petch relation, indicating that the crystallite boundaries impede the motion of dislocations to a greater extent as the crystallite size gets smaller.     

Impedance spectroscopy properties of polypyrrole doped with boric acid

The electrical conductivity and dielectric properties of polypyrrole doped with boric acid have been investigated. The direct current conductivity (dc) of the polymer increases with increasing temperature. The alternating current (ac) conductivity of the polymer obeys the power law, i.e., σ_ac(ω) = Aω^s. The alternating conductivity of polypyrrole doped with boric acid is controlled by the correlated barrier hopping model. The activation energy for alternating current mechanism decreases with increasing frequency which confirms the hopping conduction to the dominant mechanism as compared with the dc activation energy. The density of localized states N(E_F) for polypyrrole doped with boric acid was in the range of 2.5–9.2 × 10²² cm^?3 for various temperatures. The dielectric relaxation mechanism was explained on the basis of complex dielectric modulus. The imaginary modulus plot at different temperatures shows a dielectric mechanism with non-Debye relaxation. Boric acid can be a good candidate for controlling the electrical conductivity of the conducting polymer.     

Insight into the binding of copper(II) by non-toxic biodegradable material (Oryza sativa): effect of modification and interfering ions

The present studies are focused on the use of non-toxic biodegradable straw from Oryza sativa in its simple and modified forms for the binding of copper(II) ions. A relatively new “green” method was adopted for modification with urea under microwaves. The studies have been performed by using the aqueous solution of Cu(II) ions with and without the presence of Cd(II) and Pb(II) as interfering ions. FTIR analysis showed the presence of oxygen- and nitrogen-containing functional groups in simple and modified materials. The emergence of new bands and shifts in the peaks confirmed the modification. The kinetics of the process was studied using the commonly employed mathematical models. Although Elovich model seemed to fit yet coefficient of determination did not reinforce it. Pseudo-second-order model was found to explain the kinetics of the binding of metal ions by simple and modified straw. The equilibrium was studied using the non-linear approach. Based on root mean square error values, it was found that Langmuir model was the most suitable model, followed by Temkin model. Surface areas were compared for single and multi-metal systems. The effect of pH was also studied. Under the studied set of conditions, the modification of straw caused a decrease in the equilibrium time of contact and increase in the biosorption capacities. The presence of other ions decreased the capacities drastically due the competition to bind with the materials.     

Faster dynamic spatial partitioning in OpenSimulator

OpenSimulator has emerged as one of the leading tools to help researchers, developers, and practitioners working in the field of virtual worlds since it is an open-source alternative to second life, the state of the art in virtual worlds. The grid mode of OpenSimulator is highly scalable, and it places no restriction on the number of cooperating OpenSimulator instances, each of which may simulate activity in an arbitrary number of regions. However, like second life, it suffers from both over-provision and under-provision of resources due to static allocation of regions to instances and the lack of an expansion and contraction model which adjusts resource allocation according to workload. We have used OpenSimulator to implement dynamic scalability which is an integral part of our novel infrastructure presented in earlier work. This paper reports timing analysis of the basic capabilities of OpenSimulator that are used to re-locate regions to additional simulators. The focus has been on a conservative extension to OpenSimulator using existing methods. To overcome serious performance issues during reassignment of a region, we present two extended region removal methods. Comparison of timing information for both existing and extended strategies is provided on both a network of Windows systems and a cluster of Linux nodes.     

Quality practices in design organizations

Design organizations play a major role in the construction industry: they are the media that transfer the requirements of the client to the contractor and ensure that they are met. Thus they need to provide a high quality of service to ensure that their client's project achieves the best possible standards of cost, time and quality. Seventy quality practices (QP) were identified as having a bearing on the quality of service provided by the local design organizations. These quality practices were grouped into fifteen sections termed quality sections (QS). The prevalence of these practices among the local design organizations was surveyed and determined. The results indicate a significant need for improvement in the quality sections ‘working relationship’, ‘employee training and education’, and ‘performance quality audit’. The study reveals the need for the establishment of a design code, and evaluation standards for local design organizations.     

Effect of tartrazine dye on micellisation of cationic surfactants: conductometric,spectrophotometric, and tensiometric studies

The interactions between anionic dye (tartrazine) and cationic surfactants (dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide) have been studied by conductometric, spectrophotometric, and tensiometric techniques. The conductance and surface tension of dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide in pure water as well as in aqueous tartrazine when plotted with surfactant concentration gave values of the critical micelle concentration at different temperatures. As well as increasing the length of the carbon chain of surfactants, the presence of tartrazine reduces the critical micelle concentration. From specific conductivity data, the counterion dissociation constant, standard free energy, enthalpy, entropy of micellisation, surface excess concentration, surface tension at critical micelle concentration, minimum area per molecule, surface pressure at critical micelle concentration, and Gibbs energy of adsorption were evaluated. Spectroscopic studies reveal that the binding of dye to micelles brings a bathochromic shift in dye absorption spectra that indicates dye–surfactant interaction.     

Enhancement of Thermoelectric Performance in Hierarchical Mesoscopic Oxide Composites of Ca3Co4O9 and La0.8Sr0.2CoO3

The natural contradiction in enhancing electrical conductivity and thermopower in thermoelectric oxides makes it hard to improve the performance of a single thermoelectric oxide material. We report a facile method to construct a unique architecture of thermoelectric oxides that is promising to realize a simultaneous improvement of overall electrical conductivity and thermopower. Here, a series of two‐phase nanocomposites comprising of Ca₃Co₄O₉ (CCO) and La_0.8Sr_0.2CoO₃ (LSCO) has been synthesized through ball milling followed by spark plasma sintering (SPS) method. The electron microscope images reveal that the two constituents form the unique composites while retaining their individual crystalline and morphological identities. Owing to the hierarchical mesoscopic structure with nanoscale particles and submicrometer scale grain boundaries, an external strain is induced into the CCO grains by the LSCO nanoparticles to enhance the thermopower. The mesoscopic structure is also favorable for improving the electrical conductivity. Moreover, the long‐wavelength phonons can be scattered effectively from LSCO nanoparticles and the thermal conductivity is further suppressed. With compromises between power factor and thermal conductivity, the largest ZT achieved is up to 0.41 at 1000 K for the composites with 25 wt% of LSCO.