Measurement of K shell fluorescence cross sections and K shell fluorescence yields for the atomic region 22≤Z≤64 by 59.5 keV photons

A new method has been developed to determine K shell fluorescence cross section and K shell fluorescence yields. This method is based on simultaneous measurement of fluorescence radiation and scattered radiation, thus avoiding problems with measuring the source strength and source-to-detector solid angle. The K shell fluorescence cross section and K shell fluorescence yield for 21 elements in the atomic range 22£Z£64 have been measured by using a Si(Li) detector. The obtained results are compared with the other experimental, theoretical and fit values.     

Enzymatic oxidative polymerization of para‐imine functionalized phenol catalyzed by horseradish peroxidase

Enzymatic oxidative polymerization of a new para‐imine functionalized phenol derivative, 4‐(4‐hydroxybenzylideneamino)benzoic acid (HBBA), using horseradish peroxidase enzyme and hydrogen peroxide oxidizer has been investigated in an equivolume mixture of an organic solvent (acetone, methanol, ethanol, dimethylformamide, 1,4‐dioxane, and tetrahydrofuran) and phosphate buffer (pH = 5.0, 6.0, 6.8, 7.0, 7.2, 8.0, and 9.0) at different temperatures under air for 24 h. The resulting oligomer, oligo(4‐(4‐hydroxybenzylideneamino)benzoic acid) [oligo(HBBA)], was characterized using ultraviolet–visible, Fourier transform infrared (FT‐IR), ¹H nuclear magnetic resonance (NMR), cyclic voltammetry, size exclusion chromatography, differential scanning calorimetry, and thermogravimetric analyses. Polymerization involved carbon dioxide and hydrogen elimination from the monomer, and terminal units of the oligomer structure consisted of phenolic hydroxyl (–OH) groups at the ends. The polymer is mainly composed of a mixture of phenylene and oxyphenylene units according to ¹H NMR and FT‐IR analyses. Effects of solvent system, temperature and buffer pH on the polymerization have been investigated in respect to the yield and molecular weight (M_n) of the product. The best condition in terms of the highest molecular weight (M_n = 3000 g/mol, DP ~ 15) was achieved in an equivolume mixture of 1,4‐dioxane/pH 5.0 phosphate buffer condition at 35°C. Electrochemical characterization of oligo(HBBA) was investigated at different scan rates. The resulting oligomer has also shown relatively high thermal stability according to thermogravimetric analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemical Effect on L X-ray Intensity Ratios of Mercury,Lead, and Bismuth

INTRODUCTION

The information regarding the experimental values of K and L X-ray intensity ratios are important due to its wide use in many areas of basic and applied science and non-destructive elemental analysis of materials using the X-ray fluorescence technique. Chemical effects on K and L X-ray intensity ratios are not very well known, but they are an interesting subject. Some studies [1–4] addressing chemical effects on the K_β/K_α intensity ratios have been made. We investigated chemical effects [5–7] and alloying effects [8] on the K_β/K_α intensity ratios, and measured K_β/K_α intensity ratios following radioactive decay and photoionisation [9]. But there are few studies addressing chemical effects on the L X-rays intensity ratios. Iihara et a1.[10] examined chemical effects on chromium L X-rays.     

Measurement of K shell radiative transition probabilities and K, L2 and L3 shell/subshell fluorescence yields of some elements in the atomic number range 30 ≤ Z ≤ 40

K shell radiative transition probabilities and K, L₂ and L₃ shell/subshell fluorescence yields were measured using the K_β/K_α intensity ratio for seven elements in the atomic number range 30≤Z≤40 (Zn, As, Se, Rb, Sr, Y and Zr). The targets were irradiated with γ photons of energy 59.5 keV from Am-241. The obtained values were compared with the theoretical values. It was observed that the present values agree with previous theoretical results. The L₂ and L₃ subshell fluorescence yields were the first measured for the present elements.     

Synthesis and Characterization of Conducting Copolymers of Bisphenol A-Diglycidyl Ether with Thiophene Side-Groups and Pyrrole

Copolymers of bisphenol A-diglycidyl ether with thiophene side-groups and pyrrole were synthesized by electrochemical polymerization. Bisphenol A-diglycidyl ether with thiophene side-groups (DGEBATh) was obtained from the reaction between bisphenol A-diglycidyl ether (DGEBA) and thiophene-3-acetic acid. The syntheses of copolymers of DGEBATh and pyrrole were achieved electrochemically using three different supporting electrolytes, p-toluene sulfonic acid (PTSA), sodium dodecyl sulfate (SDS) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterizations of DGEBATh and copolymers were performed by combination of techniques including cyclic voltammetry, scanning electron microscopy, gel permeation chromatography, differential scanning calorimetry, ¹H-NMR and FT-IR. The conductivities were measured by the four-probe technique.     

Microwave coaxial slot bridge technique for the dielectric parameter control of liquids

The basic physical principles and construction of the device for investigation of dielectric parameters of liquids are considered. The key moment is in the using of the rigorous solution of initial boundary value problem for the resonant electromagnetic structure that is in the focus of the device. Thus all electromagnetic characteristics are calculated with the required accuracy and several rather special phenomena are taken into account.     

Average 2p subshells fluorescence yield values of some elements in the atomic number range 60 ≤ Z ≤ 90

The average 2p (L_2,3) subshells fluorescence yield (?_2,3) in 11 elements with Z ranging from 60 to 90 were measured with corporation of total L_2,3 X-ray production cross-sections. Measurements were carried out exciting L₂ and L₃ subshells of relevant elements that were exposed to beam of selected K X-rays from secondary sources. The measured values were compared with theoretical and semi-empirical values. It is clear that the present values of experimental ?_2,3 are generally smaller than the calculated and semi-empirical values for some elements in the atomic number range 60–90.