Green Nanocomposites of Natural Rubber/ Olivine Nanosilica: Viscoelastic,Mechanical, Transport and Thermal Characterizations

Silicon - Nanosilica was synthesized from a low cost raw material, olivine by a more sustainable and cost effective method. The pure nanosilica obtained was amorphous in nature with a surface area...     

Growth kinetics and lipid production using Chlorella vulgaris in a circulating loop photobioreactor

BACKGROUND: Compared with agriculture, microalgae culture promises to be a novel way of producing lipids for both food consumption and transportation fuel (biodiesel) purposes while using a minimal amount of land area. A circulating loop photobioreactor has been used to study the growth kinetics and lipid yield of Chlorella vulgaris growing on carbon dioxide as the sole source of carbon. RESULTS: Because of high photosynthetic active radiation (PAR) fluxes, C. vulgaris was observed to grow in exponential mode. The highest growth rate achieved was 0.049 h^?1 at the optimum growth conditions of 71.8 mW L^?1 PAR density, 10% CO₂ (v/v) in air and with an applied 8 h dark phase. The microalgae was observed to grow in a Monod fashion with a PAR density saturation coefficient of 2.8 mW L^?1. Light intensity showed the potential to significantly increase lipid yield, which reached a maximum of 30% (by mass) of cell dry weight. CONCLUSION: The circulating loop photobioreactor is a low‐cost bioreactor technology capable of culturing photosynthetic microalgae at high PAR densities and with uniform mixing and lighting. C. vulgaris is able to grow exponentially in this bioreactor and produce lipids at concentrations up to 30% by cell dry weight. Copyright © 2011 Society of Chemical Industry     

Characterisation of solution annealed VT-14 titanium alloy using eddy current based electrical resistivity measurements

This paper discusses characterisation of microstructures in Ti-4.5Al-3Mo-1V (VT-14) alloy specimens solutionized in the temperature range of 923K–1373K, using room temperature electrical resistivity measurements. Using phase angle of impedance change in eddy current coil as a parameter, calibration curve between resistivity and phase angle has been established using three reference specimens of known resistivity. The changes in the electrical resistivity of the specimens have been correlated with optical microscopy investigations. The electrical resistivity of unstable β phase has been compared with α and α′ phases and possible reasons for higher resistivity of β phase and lower resistivity of α′ have been given based on the rule of mixtures and scattering and mobility of electrons. The electrical resistivity of α′ martensite phase of the chosen VT-14 alloy has been determined as 1.04 αΩ-m. The studies reveal that it may be possible to identify the β transus temperature of α+β titanium alloys from the electrical resistivity data.     

Statistical two-dimensional correlation spectroscopy: its theory and applications to sets of vibrational spectra

The present study aims at developing a new form of two-dimensional (2D) correlation spectroscopy, statistical 2D correlation spectroscopy. Statistical 2D spectroscopy differs from the widely used generalized 2D correlation spectroscopy in that the former abstracts spectral features by pretreatment and by 2D maps that are limited by the correlation coefficients in the range from 1 to -1. In this paper, the theory of the new 2D method is briefly described, and then its applications are discussed to reveal spectral and concentration features of artificial model spectra, infrared spectra of polycondensation of bis(hydroxyethyl terephthalate) measured on-line, and short-wave near-infrared spectra of raw milk. The results are analyzed thoroughly and compared with those from generalized 2D correlation spectroscopy and partial least-squares loadings and scores. The most significant advantage of statistical 2D correlation spectroscopy is that the 2D correlation spectra are easy to calculate and are purely mathematical in nature, thereby eliminating any subjective involvement of an experimenter, while the inherent weakness of the method lies in its sensitivity to the noise.     

Ray and van cittert-zernike characterization of spatial coherence

We discuss a ray and a van Cittert-Zernike characterization of spatial coherence in condensers for projection systems. We present a rule of thumb with which to estimate the modulus of the coherence function at a given point of the illuminated object and a ray-tracing methodology with which to determine this modulus. For uniform illumination of the pupil we relate the modulus of the coherence function and the pupil-filling factor. We suggest that the rms of the angular ray spread at a given object point is an appropriate metric with which to characterize local coherence properties.     

Compressive deformation behavior of Al 2024 alloy using 2D and 4D processing maps

The hot deformation behavior of Al 2024 was studied by isothermal hot compression tests in the temperature range of 250–500 °C and strain rate range of 10⁻³ to 10² s⁻¹ in a computer-controlled 50 kN servo-hydraulic universal testing machine (UTM). The results show that the flow stress of Al 2024 alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. The processing map exhibits two domains of optimum efficiency for hot deformation at different strains, including the low strain rate domain at 500 °C and between 10⁻² and 10⁻¹ s⁻¹ and the high strain rate domain in 250 and 300 °C in the strain rate range of 10¹ to 10² s⁻¹. An attempt has been made in this article to generate a new hybrid 4D process map which illustrates contours of power dissipation and instability in the 3D space of strain rate, temperature, and strain.     

Role of the stimulated-emission rate in the photostability of solid-state dye lasers

The lasing and photostability characteristics of Rhodamine 6G and Pyrromethene 567 dyes dispersed in polymeric host materials have been investigated as a function of the intensities of incident pump and signal beams in a longitudinally pumped dye laser in an oscillator-amplifier configuration. A substantial reduction in the rate of photodegradation was observed under lasing conditions and with increasing signal intensity in a dye amplifier, establishing that the service lives of these materials improve with an increase in the rate of stimulated emission. We observed approximately 62% amplifier efficiency at 2 Hz operation and 10% reduction in amplifier efficiency at 10 Hz operation after exposure of 72,000 pulses by use of a Pyrromethene disk.