Dielectric characterization of rapeseed (Brassica napus L.) in the temperature range of 20-60 degrees C and at moisture contents of 8.5, 12.5 and 16% wet basis (w.b.) was performed by determining:the dielectric constant and loss factor at frequencies from 10 to 3000 MHz. This range of frequencies, includes the ISM (Industrial, Scientific and Medical) frequencies of 13, 27, 40, 915 and 2450 MHz. An open-ended coaxial probe (Speag DAK, 12) and a vector network analyzer (Agilent Technologies, E5071C) were used to measure the dielectric properties (dielectric constant and loss factor). Compressed ground samples of rapeseed at densities nearly equivalent to seed density were used. Determined data at the ISM frequencies was fitted to polynomials to represent the dependence of the dielectric constant as well as the loss factor on temperature and moisture content. The calculated penetration depth of the electromagnetic field in rapeseed at the ISM frequencies shows that at a given moisture content and temperature, it decreases with increasing frequency. The reported data are useful in designing and developing radio-frequency (RF) and microwave (MW) applicators for dielectric heating of rapeseed. (C) 2015 IAgrE. Published by Elsevier Ltd. All rights reserved.

Basal (non-stimulated) tears that are produced by accessory lacrimal glands located in conjunctiva of human eye, form tear film which in turn keeps the eye moist and lubricate; nourishes the eye; protects the eye from dust, bacterial infection and shear forces generated during eye movements and blinking; and provides a refractive surface on the corneal epithelium. Film is known to contain water, mucin, lipids, lysozyme, glucose, urea, sodium etc. In present communication, loss tangent of human tear film has been determined at 9.8 GHz microwaves by employing cavity perturbation technique at a temperature of 37 degrees C. The basal tears from a small population comprising six subjects were collected and average value of loss tangent is reported. Slater's technique was used to reduce the error caused in measuring the volume of sample. The determined values are useful to study the biological effects of microwaves on tear film as well as other parts of human eye such as eye lens and lens epithelial cells. To the best of author's knowledge, no such study is available in literature at any radio as well as microwave frequencies; therefore present determinations are first of its kind.

A modified form of existing geometrical set-up of sample holder and coaxial line probe which is coupled with Agilent E5071C vector network analyzer, is used to determine the dielectric constant epsilon' and loss factor epsilon '' of corn flour at tapped densities 0.69, 0.63, 0.54 and 0.46 g/cm(3) that correspond to moisture contents 8.8%, 12.6%, 17.4% and 22.7% wet basis respectively; and in the temperature and frequency ranges 25-75 degrees C and 0.2-10 GHz respectively. Measurements made at tapped density helps in designing microwave (MW) applicators as this density remains almost unchanged under unintentionally produced mechanical impacts, when flour is transported from grinding unit to applicators. Results show that epsilon' decreases smoothly with increase in frequency at all temperatures and tapped densities, while epsilon '' decreases up to similar to 1 GHz and then starts increasing. At a given frequency, change in both epsilon' and epsilon '' with tapped density does not follow a particular trend for temperatures up to 50 degrees C; while increasing trend with decrease in tapped density is observed above 50 degrees C. Under strict controlled conditions such as power of electromagnetic field, exposure time, and desired maximum temperature of corn flour to get the acceptable quality of flour, these dielectric properties are beneficial to develop MW applicators for the purpose of thermal treatment to flour. (C) 2015 Elsevier Ltd. All rights reserved.

Linear attenuation coefficient of irregular targets having unknown thickness (La, Pr, Nd, Gd, Tb, Ho and Er) and regular targets of known thickness (Mo, Ag, Sn, W and Pb) at 59.54keV have been measured by using a new technique named Advanced Two Media (ATM) method. In this modified Advanced Two Media method pure metallic foils have been used as a mediums 1 and 2. The obtained results from Advanced Two Media method and transmission geometry are in good agreement with theoretical values of WinXCOM.

Total mass attenuation coefficient, total photon interaction cross-section, effective atomic numbers (Zeff) and electron densities (Ne) of Aniline (C6H5NH2), Cyclohexane (C6H12), Glycerine (C3H5(OH)3), Butyl alcohol N-(C4H9OH), DMSO – dimethyl sulfoxide (C2H6OS), Methyl ethyl-ketone (C4H8O), Xylene (C8H10), Acetophenone (C8H8O) and Triethyl amine (C6H15N) have been measured at 59.54keV energy photon emitted by 100mCi 241Am point source employing narrow beam transmission geometry. Obtained results have been compared with theoretically calculated values of XCOM (Berger and Hubbel, 1987) and FFAST (Chantler et al., 2005). Mixture rule was employed to calculated theoretical mass attenuation coefficient values for each sample. Good agreement has been observed between experimental and theoretical values within experimental uncertainties.

LIII subshell absorption edge jump factor and jump ratio of elements W, Au and Hg have been measured experimentally using EDXRF technique using X-PIPS Si (Li) detector. 90° reflection geometry has been used to detect the emitted fluorescent L X-rays from the target elements excited by 59.54keV gamma-rays emitted from 241Am radioactive point source. Measured values of these parameters have been compared with different theoretically calculated values obtained from XCOM (Berger et al., 2005, Chantler et al., 2005). Result shows a fairly good agreement within experimental uncertainty. These parameters have been reported for the first time for aforesaid elements using this methodology.

L3-subshell absorption jump ratios and jump factors of Pb, Th and U have been measured by using EDXRF spectroscopy technique. Measured values of jump factors and jump ratios of Pb, Th and U are compared with theoretical values obtained from WinXcom programme [Radiat. Phys. Chem. 2001 (60) 23] and Chantler et al. [18] (http://physics.nist.gov/ffast). The experimental results are in agreement with the theoretical values within uncertainties of measurements. The measured values of jump factors and jump ratios are reported for the first time.

Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios in elements Mn, Fe, Co, Cu, Zn, As and Sr using an X-PIPS Si(Li) detector. 90° reflection geometry has been used to detect the emitted fluorescent K X-rays from the target elements excited by 59.54keV gamma-rays emitted from an 241Am radioactive point source. Measured values of these parameters have been compared with different theoretically calculated as well as with other available experimental values. It is found that the present results fairly agree with theoretically calculated and experimental values within experimental uncertainties.

Linear attenuation coefficients of regular as well as irregular shaped archaeological samples of FaLG (flyash–lime–gypsum) of unknown thickness have been measured employing ‘simplified two media’ method. Seven different liquid materials plus air have been used as media to measure attenuation coefficient of these samples. Obtained results have been compared with those for regular shaped samples. Experimental values have also been compared with theoretical values calculated from FFAST and XCOM. A good agreement has been observed between experimental and theoretical values. Present measurements employing ‘simplified two media’ method have been reported for the first time for checking its validation and reliability.

Energy, charge and Z dependence of L shell X-ray intensity ratios in the energy range 0.9 MeV to 15 MeV has been investigated in Au. TI, Bi, Th and U for incident carbon (i.e. C+q where q=1,2,3) projectile. The intensity ratios and first I-l/I-gamma , I-alpha/I-gamma and I-beta/I-gamma first decreases with increase in energy, attain minimum value and then start increasing. The minimum value of I-l/I-gamma and I-alpha/I-gamma falls in the energy range (0.9MeV to 3MeV) and of I-beta/I-gamma in the energy range 6MeV to 15MeV for all elements. It has also been investigated that for a particular energy and Z, values of I-l/I-gamma , I-alpha/I-gamma and I-beta/I gamma I, increases with decrease in value of charge (q). Similarly for particular energy and charge, values of I-l/I-gamma , I-alpha/I-gamma and I-beta/I-gamma increases with increase in Z value. Also a comparison has been made among the intensity ratios evaluated using two different sets of parameters i.e. (fluorescence yield omega(i) where i=1.2,3 for L-1, L-2 and L-3 sub shells and Coster Kronig transitions f(ij) where i,j=1,2,3 for L-1, L-2 and L-3 sub shells) given by Krause et al and Campbell.

Measurement of differential M-shell X-ray emission cross-sections for bismuth at different angles has been reported. The present results confirm the prediction of the calculations of Flugge et al. [S. Flugge, W. Mehlhron, V. Schmidt, Phys. Rev. Lett. 29 (1972) 7] that the atomic inner-shell vacancies produced after photoionization are aligned and the X-ray emission from the filling of these vacancy states with j>1/2 are anisotropic. These results contradict the predictions of Cooper and Zare [J. Cooper, R.N. Zare, Atomic Collision Processes, vol. xic, Gordon & Breach, New York, 1969, p. 317] that, after photoionization of inner shells, the vacancy states have equal population of magnetic substates and the subsequent X-ray emission is isotropic.

The total M shell relative photoionization cross-sections for Au, Pb, Th and U have been measured in the energy region 6–12 keV. External conversion K X-rays of suitable elements has been employed as incident photons to photo ionize the total M shell of elements under investigation. The method provides relative cross-sections therefore does not make use of theoretically calculated average M shell fluorescence yields which involve uncertainties of the order of 20%. No evidence of deviation from calculated values of cross-sections have been observed within experimental errors for all incident photon energies.

Measurement of differential K shell X ray intensity ratios, I(K-alpha)/I(K-beta) for Copper and Gadolinium at 60 degrees-100 degrees has been reported. A new approach has been developed to know quantitatively the isotropy in K shell X-rays. The present results confirm the prediction of the calculations of Flugge et al. (1), Scofield(2), Berezhko et al.(3) and Cooper and Zare(4) that, after photoionization of inner shells, the vacancy states with J = 1/2 has equal population of magnetic sub states and the subsequent K shell X-ray emission is isotropic.

In the present work, relative K-shell photoionization cross-sections of 6-25 keV photons in S, Ca and V are measured. Experimental results are found to agree with calculated theoretical values within the experimental uncertainties.

In the present communication, the decay of surface charge density of bees wax and the role of a variety of relaxation times in describing the nature of charge carriers have been studied in detail. Thermo-electrets of bees wax were prepared under different conditions of polarizing field, temperature and time. The results of present investigations show that a single line does not fit the complete exponential decay of the surface charge. The values of decay constants range from 2.0x10(2) sec to 1.3x10(7) sec. Due to the presence of a large number of dipoles and ions of different kinds in bees wax, a number of dipole relaxation frequencies are expected.

The energy dependence of the L subshell X-ray intensity ratios L-alpha/L-l, L-alpha/L-beta and L-alpha/L-r in elements Sm, Lu, Gd and Tb has been systematically investigated by making measurements at eight different incident X-ray energies and the measured values have been compared with the theoretically calculated values. The comparison shows a good agreement in all the cases. As expected from theory, the experimental values of L-alpha/L-l in all these elements are found to be independent of the incident photon energies within the uncertainties of the experimental measurements, however, the ratio L-alpha/L-gamma is found to be Strongly energy dependent.

The cross-sections of M x-ray emission following photoionization of L and M shell electrons in Au, Pb, Th and U by 59.57 keV gamma rays were measured. The experimental values of cross-sections were found to be higher than those calculated from the theoretical values of L and M shell photoionization cross-sections, the L(i) subshell to M shell vacancy transfer probabilities and M shell average fluorescence yields. The transfer of vacancies from the L(i) subshell to the M shell was found to play a significant role in M x-ray emission. The present status of the experimental and calculated values of the cross-sections is discussed.

M shell X-ray production cross sections in thick targets of Pb, Th and U by K X-rays of Rb, Nb and Mo respectively have been measured. As the incident K X-ray energies are above the L3 edge but below L2 edge energies of the respective target elements under reference, the M X-rays are produced not only due to direct interaction of incident photons with M shell electrons but also due to the decay of L3 subshell vacancies to M shell. The measured values have been compared with those calculated using known values of M and L3 subshell photoionization cross sections and fluorescence yields etc, wherever possible. The percentage contribution due to shift of L3 subshell vacancies to M shell to the total M shell X-ray emission were evaluated and it is seen that the shift contributes nearly 50% of the total M X-rays produced in the case while it is nearly 75% in the case of Th and U at the incident energies under reference.

AbstractCross‐sections for the production of Ll, Lα, Lβ and Lγ x‐rays in 22 elements (57 ≤ Z ≤ 92) by photons of 13 different energies in the range 8–50 ke V are reported. The experimental values of the cross‐sections were determined by measuring the absolute yield of L subshell x‐rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. The theoretical values of the cross‐sections were calculated from the theoretical/semi‐empirical values of subshell photoionization cross‐sections, fluorescence yields, Coster‐Kronig transition probabilities, intra‐shell transition probabilities and radiative decay rates. The present and previous measured and calculated values of the cross‐sections are tabulated to bring out the existing status of L x‐ray production cross‐sections.

Cross-sections for the production of Ll, L alpha, L beta and L gamma x-rays in 22 elements (57 less than or equal to Z less than or equal to 92) by photons of 13 different energies in the range 8-50 keV are reported. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell x-rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. The theoretical values of the cross-sections were calculated from the theoretical/semi-empirical values of subshell photoionization cross-sections, fluorescence yields, Coster-Kronig transition probabilities, intra-shell transition probabilities and radiative decay rates. The present and previous measured and calculated values of the cross-sections are tabulated to bring out the existing status of L x-ray production cross-sections.