Near‐zero thermal expansion transparent lithium aluminosilicate glass‐ceramic by microwave hybrid heat treatment

The material of choice for space applications which demand very high dimensional stability is lithium aluminosilicate (LAS) based Ultra Low thermal Expansion Glass‐Ceramic (ULEGC). Generally, the controlled crystallization process recommended for the processing of transparent ULEGC involves a long soaking duration to achieve the required crystal number density. This paper brings out the process optimization procedure adopted for realizing transparent and nanocrystalline ULEGC from conventionally processed LAS glass using microwave‐assisted (hybrid) crystallization. The experimental strategy involves two stages (i) identification of the optimum crystallization temperature (T_c) under a microwave field (ii) optimization of a microwave‐assisted crystallization process to achieve near zero Coefficient of Thermal Expansion (CTE).. Optimum heat‐treatment schedules for nucleation and crystallization under a microwave environment were found to be 720°C/24 hours and 775°C/0.3 hours, respectively. The optimized heat‐treatment condition revealed the efficacy of the microwave hybrid heating, by producing nanocrystalline (35‐50 nm) and transparent (>82%) ULEGC having a thermal expansion of ?0.03 × 10^?6 K (0°C to 50°C).     

Instruction level power analysis and optimization of software

The increasing popularity of power constrained mobile computers and embedded computing applications drives the need for analyzing and optimizing power in all the components of a system. Software constitutes a major component of today's systems, and its role is projected to grow even further. Thus, an ever increasing portion of the functionality of today's systems is in the form of instructions, as opposed to gates. This motivates the need for analyzing power consumption from the point of view of instructions—something that traditional circuit and gate level power analysis tools are inadequate for. This paper describes an alternative, measurement based instruction level power analysis approach that provides an accurate and practical way of quantifying the power cost of soft-ware. This technique has been applied to three commercial, architecturally different processors. The salient results of these analyses are summarized. Instruction level analysis of a processor helps in the development of models for power consumption of software executing on that processor. The power models for the subject processors are described and interesting observations resulting from the comparison of these models are highlighted. The ability to evaluate software in terms of power consumption makes it feasible to seach fow low power implementations of given programs. In addition, it can guide the development of general tools and techniques for low power software. Several ideas in this regard as motivated by the power analysis of the subject processors are also described.     

Influence of scattering on transmission through long-period fiber gratings and tunable microstructure fibers

Controlled optical scattering within or around an optical fiber provides a potentially useful mean for adjusting its transmission characteristic. This approach can complement conventional methods based on the establishment of well-defined variations in the index of refraction of the core or the cladding of the fiber. We describe the use of a highly scattering submonolayer of nanoparticles deposited onto the fiber surface for adjusting the resonance wavelength, depth, and width of an in-fiber long-period grating filter. We also introduce a polymer-dispersed liquid-crystal material that has a thermally tunable scattering cross section and can be incorporated into the channels of a microstructure optical fiber; this system may provide the means for a fiber-based scattering switch.     

Hydrothermal synthesis of NH2-UiO-66 and its application for adsorptive removal of dye

In this research paper we report hydrothermal synthesis of NH₂-UiO-66, a metal organic framework (MOF) with zirconium as metal and amino terephthalic acid as a linker. The synthesized MOF was characterized by XRD, FTIR, SEM and BET surface area. As a potential application in water treatment, an adsorptive removal of safranin dye was studied using the synthesized material. The effect of initial concentration and pH of the dye solution was studied on the dye adsorption capacity of the material. An optimum set of conditions resulting into maximum dye adsorption was found out. The maximum adsorption capacity of the MOF was observed to be 390?mg/g at neutral pH of the solution and at room temperature. The experimental data was fitted with Langmuir, Freundlich and Temkin adsorption isotherm models. The kinetics of adsorption was studied using pseudo first order and pseudo second order model. The dye adsorption mechanism was also attempted.     

Enhanced tolerance and remediation of anthracene by transgenic tobacco plants expressing a fungal glutathione transferase gene

Plants can be used for remediation of polyaromatic hydrocarbons, which are known to be a major concern for human health. Metabolism of xenobiotic compounds in plants occurs in three phases and glutathione transferases (GST) mediate phase II of xenobiotic transformation. Plants, although have GSTs, they are not very efficient for degradation of exogenous recalcitrant xenobiotics including polyaromatic hydrocarbons. Hence, heterologous expression of efficient GSTs in plants may improve their remediation and degradation potential of xenobiotics. In the present study, we investigated the potential of transgenic tobacco plants expressing a Trichoderma virens GST for tolerance, remediation and degradation of anthracene—a recalcitrant polyaromatic hydrocarbon. Transgenic plants with fungal GST showed enhanced tolerance to anthracene compared to control plants. Remediation of ¹⁴C uniformly labeled anthracene from solutions and soil by transgenic tobacco plants was higher compared to wild-type plants. Transgenic plants (T₀ and T₁) degraded anthracene to naphthalene derivatives, while no such degradation was observed in wild-type plants. The present work has shown that in planta expression of a fungal GST in tobacco imparted enhanced tolerance as well as higher remediation potential of anthracene compared to wild-type plants.     

Development of Integrated Sediment Rating Curves Using ANNs

Correct estimation of sediment volume being carried by a river is very important for many water resources projects. Conventional sediment rating curves, however, are not able to provide sufficiently accurate results. Artificial neural networks (ANNs) are a simplied mathematical representation of the functioning of the human brain. Three-layer feed-forward ANNs have been shown to be a powerful tool for input-output mapping and have been widely used in water resources problems. The ANN approach is used to establish an integrated stage-discharge-sediment concentration relation for two sites on the Mississippi River. Based on the comparison of the results for two gauging sites, it is shown that the ANN results are much closer to the observed values than the conventional technique.     

Measurement of specific energy losses of individual fission fragments with a back-to-back δE−E detector system

The specific ionization of fission fragments of specified charge and $\text{E}\text{M}$ values in thermal neutron induced fission of ²³⁵U have been measured employing a back-to-back gridded ionization chamber ΔE-semiconductor detector E setup. The measurements were carried out for the case of a mixture of argon (95%) and methane (5%) gases at two gas pressures, 44 Torr and 270 Torr. The experimental data for the lower gas pressure were used to determine the effective charge parameter γ for the fragments at various velocities. These γ-values have been used to compute the fragment energy losses at the higher gas pressure and are compared with the measured energy loss values.     

A hysteresis in plasticized poly(vinyl chloride)

Plasticized poly(vinyl chloride) formulations were prepared in solid and foam form, and mechanical hysteresis was measured by low-speed tension and compression on an Instron tester and by high-speed rebound on a resiliometer. Hysteresis was greatest in copolymers with vinyl acetate, at low plasticizer concentration, with inefficient plasticizers, at high concentrations of reinforcing fillers, at high expansion to low density, and at high speed of testing. Conversely, resilience was greatest at high plasticizer concentration, with more efficient plasticizers, with non-reinforcing fillers, and at high density.