An in vitro L-band EPR study with whole human teeth in a surface coil resonator. Radiat

Abstract L-band EPR measurements were done in vitro on extracted human teeth with the objective to evaluate the feasibility of retrospective in vivo EPR dosimetry. In a recent study, the relative contributions of individual tooth components (enamel, crown dentin and root) to the total response of a whole tooth inside an L-band surface coil resonator was investigated. In the present work, the gamma-dose response curves were evaluated for di erent EPR signal evaluation methods, using 35 whole teeth with absorbed doses in the range 1-100 Gy. The paper reports on the ÿrst attempt to deconvolute the single composite L-band EPR line in components due to CO − 2 and native radicals. The L-band EPR spectrum of teeth could be approximated by combining powder-simulated spectra of orthorhombic and quasi-axial signals of the CO − 2 radical and an isotropic signal of the native radicals. Among the applied EPR signal evaluation methods, the evaluation by spectrum deconvolution revealed the lowest detection limit for absorbed dose. A detection limit of about 0:5 Gy was estimated for the currently available L-band equipment

Evaluation of the Native Killer Yeasts against the Postharvest Phytopathogenic mould of Balady Orange Fruits

Yeasts are some of the most important postharvest biocontrol agents (BCAs). Postharvest oranges frequently deteriorate due to green and blue moulds, leading to significant economic losses. The purposes of the present study were to isolate blue and green moulds from infected orange fruits, to assess the ability of killer yeasts isolated from healthy orange fruits and leaves from orange orchards to control blue and green moulds and to evaluate the additive effect of BCAs in combination with 2% sodium bicarbonate (SBC), 2%, sodium benzoate (SB), 2% calcium chloride, 0.2% salicylic acid (SA) or 0.5% chitosan. Among eight fungi isolated from orange fruits showing symptoms of green and blue mulds infection, two were identified as P. digitatum and P. italicum and selected for in vitro assays. Twenty eight yeast isolates were obtained from orange leaves and from the surface of fruits. All yeasts exhibited high killer activity. Twelve yeasts reduced 22.5 –70% of P. digitatum growth while seven isolates reduced 21.1- 68.5% of P. italicum growth. The most potent yeast isolates were identified as Candida pseudotropicalis, Candida salmanticensis, Candida membranifaciens and Pichia guilliermondii. Combination of the BCAs, C. pseudotropicalis, C. salmanticensis and P. guilliermondii with SBC, CaCl2 or chitosan increased their effectiveness against P. digitatum. While combination of C. pseudotropicalis, C. membranifaciens and P. guilliermondii with these natural compounds decreased their effectiveness against P. italicum. Combination of C. membranifaciens with SA increased its effectiveness against P. digitatum. Sodium benzoate has additive effect on C. pseudotropicalis against P. digitatum and C. pseudotropicalis and P. guilliermondii against P. italicum

Optimization of visible photoluminescence emission from Ni-Zn ferrite thin films

Ni-Zn ferrite films with different thicknesses were prepared by the spray method, aiming to study the relationship between the annealing effect in an oxygen rich environment and the structural, optical properties and photoluminescence emission. X-ray diffraction (XRD) analysis used with Rietveld refinement showed that all prepared samples had a single spinel phase structure. Likewise, the Fourier transform infrared (FTIR) spectra confirmed the phase formation of Ni-Zn ferrites by appearing in both of the two characteristic absorption bands which are related to the tetrahedral and octahedral sites. For annealed thin film samples of Ni-Zn ferrite, the atomic force microscope (AFM) surface morphology exhibits pinning structure on the surface in nanoscale height, whereas for un-annealed samples, there are hills and valleys cover a broad region. The different electronic transitions were estimated from the UV-visible transmission spectrum. Strong photoluminescence (PL) intensity in the visible range was observed under the excitation of UV radiation. The intensity of the PL signal was strongest at a film thickness of 750 nm then decreased for higher thicknesses. This could be interpreted by using proposed energy level structures based on the transmission spectrum of the investigated samples. The strong PL intensity introduces the samples as a direct optical detector for UV radiation

Enhancement of magnetization and optical properties of CuFe2O4/ZnFe2O4 core/shell nanostructure

Abstract In this work, core/shell of CuFe2O4/ZnFe2O4 nanostructure composite was prepared by hydrothermal method. X-ray diffraction (XRD) analysis, transmission electron microscope imaging, energy dispersive X-ray (EDX), and Fourier transform infrared techniques were used to prove the phase formation, morphology, elemental analysis, and cation distribution of core/shell structure, respectively. Furthermore, measurement of the optical properties proved the decrease of photoluminescence (PL) efficiency. The magnetic measurements showed an enhancement of the magnetization by about 63% relative to pure Cu ferrite, and the magnetization curve exhibited superparamagnetic behavior. These results were explained in terms of the depression of the magnetic dead layer thickness in the core/shell structure. The results unleash the promising applications of the prepared samples as transformer cores in the high frequency range and as a photocatalytic agent for water purification and hydrogen production

Influence Parameters on Nitriding Process of Ferromanganese Alloy

A 24 factorial design technique was used to investigate the magnitude effect of temperature, time, carbon percent, and pressure of the nitriding process of gas solid reaction of ferromanganese. The design was based on experiments results obtained from nitriding of two grades of ferromanganese alloys containing 0.23% C and 7.1% C at temperatures 700°C and 950°C, during time of 2 hours and 6 hours and with nitrogen pressure of 1 and 8 bar. The required calculations were carried out by Matlab. It was found that the highest positive effect was temperature while the carbon content has the highest negative effect. Nitrogen pressure has more positive effect than time. The interaction combination between two parameters or more of temperature, nitrogen pressure, and time has positive influence with different extent. The interaction combination between carbon and one or more of parameters of time, temperature, or nitrogen pressure has negative effect on nitriding process. The driven models were found to be in good agreement with the experiments and published work of nitriding process of ferromanganese containing different carbon contents (0.23–7.1%) in temperature range 700°C–950°C, with nitrogen pressure up to 8 bar, and during time of 2–6 hours

Construction and characterization of a phototherapy radiometer for optical radiation measurements

379-382It is necessary to measure the irradiance levels to evaluate the effective dose delivered to the neonate from phototherapy devices. For such purpose, a broadband phototherapy radiometer has been used for measuring these phototherapy irradiance doses of plurality types of phototherapy sources. A phototherapy radiometer has been designed and during the construction its optical characteristics has been tested in collaboration between the National Institute of Standards in Egypt (NIS) and Department of Research And Development, Medical Engineering Group (MEG) Company. The most parameters required to characterize the performance of radiometer are the responsivity and uniformity. Then the present radiometer has been compared to other two available portable phototherapy radiometers in irradiance levels measurement. The calibration has been settled and the expanded uncertainties has been calculated according to the Guide to the expression of uncertainty in measurement (GUM) at coverage factor k = 2. The designed radiometer has responsivity range 415-495 nm with FWHM 35 nm which covers the phototherapy blue band. The radiometer results output summarized as; quantum efficiency is 84%, the uniformity 72% and measuring irradiance range 100-2500 µW.cm-2