A New Electron Paramagnetic Resonance Method to Identify Irradiated Soybean

ABSTRACT:  Low-dose gamma irradiation causes minimal changes in food matrix making identification of radiation-processed foods a challenging task. In the present study, soybean samples were irradiated with commercially permitted gamma radiation dose in the 0.25 to 1.0 kGy range for insect disinfestations of food. Immediately after irradiation electron paramagnetic resonance (EPR) spectrum of the skin part of soybean showed a triplet signal ( g  = 2.0046, hyperfine coupling constant  hfcc  = 3.0 mT) superimposed on naturally present singlet. These signals were characterized as cellulose and phenoxyl radicals using EPR spectrum simulation technique. Kernel part of the samples exhibited a short-lived, radiation-induced singlet of carbon-centered radical superimposed on naturally present sextet signal of Mn²⁺. A detailed study on relaxation and thermal behavior of induced radicals in skin part was carried out using EPR spectroscopy. These findings revealed that progressive saturation and thermal characteristics of the induced radicals may be the most suitable parameters to distinguish soybean subjected to radiation dose as low as 0.25 kGy from thermally treated and nonirradiated samples, even after a prolonged period of storage.     

Electrical and dielectric properties of sol–gel derived mullite doped with transition metals

Highly crystallized mullite composite has been synthesized at 1000 °C and 1300 °C via sol–gel technique in the presence of transition metal ions such as cobalt, nickel and copper. The dielectric properties (dielectric constant, loss tangent and a.c. conductivity) of the composites have been measured at room temperature and their variation with increasing frequency and concentration of the doped metals has been investigated. The composite doped with nickel exhibits minimum dielectric constant of 3.15 at 0.002(M) concentration at a frequency of 1.5 MHz. Experimental data shows a linear increase in a.c. conductivity with increasing concentration of metal doping ions .The dielectric constant and loss tangent of the composites are within the range of requirements for commercial use in electronics.     

Control of Slag Formation, Foaming, Slopping, and Chaos in BOF

Decarburization, slag formation, foaming, and slopping in basic oxygen furnace (BOF) can now be partly understood, and to some extent predicted with the help of several on-line measurements and on-line control models. The principal reaction in BOF is decarburization. The bulk of the decarburization takes place in the turbulent region of jet impact irrespective of the fact whether the slag is solid, liquid or foamy. Metal droplets are ejected from the jet impact zone but it is difficult to distinguish the decarburization occurring in the bulk metal from that occurring in the droplets. Slag in BOF is heterogeneous and always contains some entrained gas bubbles and solid material (either un-dissolved or precipitated). At no stage the slag is 100 % liquid. A significant part of the metal droplets fall back and travel through the semi liquid slag. Through this mechanism the droplets can cause slag foaming and slopping in the BOF. Phenomenon of slag foaming and slopping can be monitored and controlled by following, dynamically, the audio signals, gas flow rate and composition, by tracking ‘Chaos’ in chemical reactions, by manipulating the chaotic attractors, and by monitoring the lance water temperature and weight. Relative stability potential (RSP) diagrams are found to be a good indicator of the dynamics of process inside the BOF and help in advance prediction of the impending chaos.     

Application of EPR spectroscopy to identify irradiated Indian medicinal plant products

A study of gamma-irradiated Indian medicinal plant products was carried out using electron paramagnetic resonance (EPR) spectroscopy. Improved approaches like high-power measurement, microwave saturation, and thermal behavior of the radicals were explored for detection of irradiation. Aswagandha (Withania somnifera), vairi (Salacia reticulata), amla (Emblica officinalis), haldi (Curcumin longa), and guduchi (Tinospora cordifolia) exhibited a weak singlet at g = 2.005 before irradiation. Aswagandha, immediately after radiation treatment, revealed a complex EPR spectrum characterized by EPR spectrum simulation technique as superposition of 3 paramagnetic centers. One group of signal with organic origin was carbohydrate and cellulose radical and the other was isotropic signal of inorganic origin (g|| = 2.0044 and g [perpendicular line] = 1.9980). However, other products did not exhibit any radiation-specific signal after irradiation. Power saturation and thermal behavior techniques were not suitable for these products. However, amongst all the 3 approaches, high-power measurement of EPR spectra emerged as a suitable technique in identification of the irradiated aswagandha. PRACTICAL APPLICATION: Gamma-irradiation confirms hygienic quality and improves shelf life of food and other products. However, there is a lack of international consensus over considering this as a general application and different regulations are being enforced. EPR is one of the most promising techniques to identify irradiated foodstuffs for regulatory requirements but it has many limitations. Improved approaches based on the EPR technique explained in this study may be useful to identify irradiated products and become beneficial to food regulators and food irradiation enterprises to enhance confidence in irradiation technology.     

Improvements on "fast space-variant elliptical filtering using box splines"

It is well-known that box filters can be efficiently computed using pre-integration and local finite-differences. By generalizing this idea and by combining it with a nonstandard variant of the central limit theorem, we had earlier proposed a constant-time or O(1) algorithm that allowed one to perform space-variant filtering using Gaussian-like kernels. The algorithm was based on the observation that both isotropic and anisotropic Gaussians could be approximated using certain bivariate splines called box splines. The attractive feature of the algorithm was that it allowed one to continuously control the shape and size (covariance) of the filter, and that it had a fixed computational cost per pixel, irrespective of the size of the filter. The algorithm, however, offered a limited control on the covariance and accuracy of the Gaussian approximation. In this paper, we propose some improvements of our previous algorithm.     

Sparsity-driven reconstruction for FDOT with anatomical priors

In this paper we propose a method based on (2, 1)-mixed-norm penalization for incorporating a structural prior in FDOT image reconstruction. The effect of (2, 1)-mixed-norm penalization is twofold: first, a sparsifying effect which isolates few anatomical regions where the fluorescent probe has accumulated, and second, a regularization effect inside the selected anatomical regions. After formulating the reconstruction in a variational framework, we analyze the resulting optimization problem and derive a practical numerical method tailored to (2, 1)-mixed-norm regularization. The proposed method includes as particular cases other sparsity promoting regularization methods such as l(1)-norm penalization and total variation penalization. Results on synthetic and experimental data are presented.     

Biodegradation of Chemically Modified Jute Fibers

Degradation of lignocellulosic fibers such as untreated jute fibers and those treated with an alkaline solution of neem oil and phenolic resin are studied by monitoring enzyme activities during burial of fibers within a compost of organic soil and animal refuse. Results indicate that biodegradation of fibers is dominated initially by enzymatic hydrolysis of hemicellulose and amorphous cellulose and subsequently by crystalline cellulose degradation. For neem oil and phenolic resin treated fibers, the degradation of hemicelluloses and cellulose were found to proceed at a remarkably slower rate compared to untreated fibers due to relative nonavailability of degradable matter.     

MILD HYDROCRACKING — A STATE OF THE ART

ABSTRACT

This paper is a brief, but not exhaustive review of the literature of the catalytic mild hydrocracking processes. It includes data characterizing reactivities, reaction network and kinetics of mild hydrocracking reactions. This review is designed for use as a reference for further research and development work in the field of mild hydrocracking.     

Third order lowpass Butterworth filter function realisation using CFA

A new realisation scheme for third order lowpass Butterworth filter function (BFF) using two CFA devices and few RC components is presented. The design equations utilise the transadmittance elements of the devices. The maximally flat response at select frequencies in the range 5 MHz ≤ f _o ≤ 30 MHz had been verified with PSPICE macromodel simulation and by hardware circuit implementation using the AD-844 device. The active sensitivities are quite low. The simulation result and the measured responses are included for f _o = 5.1 MHz and 22.2 MHz.     

An integral approach for simulation of vapour film dynamics around a spherical surface

The dynamics of a thermally driven vapour film around a solid sphere has been investigated here with both the sphere and the annular film surrounded by a large water pool. Integral models based on constant and variable vapour-phase densities have been developed here for studying a spherico-symmetric phase change problem for two immiscible phases, vapour and liquid around a hot sphere. Governing equations for both liquid and vapour phases are converted into a set of non-linear ODEs. Effects of distinct density on interface condition and density variation of vapour phase are taken into account both in energy equation of vapour phase and also in interfacial mass and energy balance. The present models have been validated with available analytical, incompressible Volume of Fluid (VOF) and experimental results of growth and collapse of either bubble or vapour film. A simple model, based on scale analysis, was evolved that successfully captured the non-monotonic growth of the film, as observed by the more detailed models under certain degree of liquid subcooling. In addition, the case of very small thermal boundary layer in the liquid side has been successfully studied for which the VOF model required very fine grid. It has been observed that the effect of density variation in the integral model results in marginally higher film growth at higher temperature. However, the effect of radiation on the film growth was found to be quite substantial. The integral model not only incorporates the effects of vapour-phase temperature variation and radiation exchange of heat but also is computationally several-fold efficient with respect to the VOF model.