Determination of tritium concentrations in humans before the development of a nuclear power plant in Turkey

The most widely used method to determine the level of tritium in humans is testing urine. Tritium concentrations in urine samples of 100 persons aged 18–66 years selected randomly from a pilot region in Turkey were analysed. The average activity concentration of urine samples was 4.66?±?1.94?Bq?L^?1 and the maximum activity concentration was 27.91?Bq?L^?1. The minimum detectable activity was 2.38?Bq?L^?1. The annual effective dose from tritium was also evaluated on the basis of the measurement results and reference values recommended by the International Commission on Radiological Protection. The effective doses for males and females were 4.56 and 3.54?nSv, respectively. These results were lower than the permissible annual effective dose for members of the public.     

Electric impedance study of elastic alternating propylene-carbon monoxide copolymer (PCO-200)

The electrical properties of elastic alternating propylene-carbon monoxide copolymer (PCO-200) were investigated using the impedance spectroscopy technique. The results revealed a phase transition at about 70 °C where the material transforms from its insulating phase of conductivity in the order of 6×10⁻⁹ to about 9×10⁻⁵ (Ω m)⁻¹, The second phase is characterized by temperature dependent electrical relaxation phenomena. The plot of the complex electric modulus and the complex impedance yields semicircles in the temperature range 70 up to 110 °C and a decreasing radius with increasing temperature. The activation energy was found to be in the order of 0.8 eV.     

Evaluation of Quantitative Sulfur Speciation in Gas Oils by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Validation by Comprehensive Two-Dimensional Gas Chromatography

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been applied for the quantitative speciation of sulfur containing compounds in gas oil (GO). For this purpose, ionization and mass spectrometric parameters have been studied and optimized with a set of standard compounds and GO samples. Comprehensive two-dimensional gas chromatography (GCxGC) was used as the reference method. To allow a quantitative comparison between FT-ICR MS and GCxGC results for GO samples, FT-ICR MS parameters were optimized and data obtained by both techniques were standardized. Response factors were established for two ionization modes: atmospheric pressure photo ionization (APPI) and electrospray after selective derivatization of sulfur compounds (MeESI). To test the validity of the developed MS methods, a third GO was analyzed and response factors were applied. Comparison with GCxGC results showed good agreement for sulfur families (deviation within 5% and 15% for MeESI and APPI data, respectively). Abundances of individual isomer groups match within 40% in most cases. These results principally demonstrate the suitability of FT-ICR MS for a quantitative analysis of sulfur compounds (by DBE and carbon number distribution pattern) in petroleum middle distillates. This approach has the potential to be extended to higher- and non-boiling petroleum fractions where quantitative speciation is presently not available.     

A facile solvent free Claisen-Schmidt reaction: synthesis of α,α'-bis-(substituted-benzylidene)cycloalkanones and α,α'-bis-(substituted-alkylidene)cycloalkanones

Solvent-free Claisen-Schmidt reactions of cycloalkanones with various substituted benzaldehydes (aryl aldehydes) using solid NaOH (20 mol%) and applying a grinding technique were studied. Quantitative yields (96-98%) of α,α'-bis-(substituted-benzylidene)cycloalkanones were obtained. Aliphatic aldehydes also provided α,α'-bis-(substituted-alkylidene)cycloalkanones in very good yields with minor amounts of a-(substituted-alkylidene)cycloalkanones. The catalytic performance of solid NaOH was examined. The molar ratio of NaOH was optimized. The catalytic effect of solid NaOH was also evaluated by comparing it with KOH, NaOAc, and NH(4)OAc and it turns out that 20 mol% of solid NaOH was good enough to catalyze the Claisen-Schmidt reactions of cycloalkanones with various substituted benzaldehydes. Additionally, the regioselectivity of the Claisen-Schmidt reaction of acetone with benzaldehyde was examined. Using the same method, we could synthesize the corresponding bis-benzylidene- and mono-benzylideneacetone separately in 98% and 96% yields, respectively.     

First seconds in a building's life-in situ synchrotron X-ray diffraction study of cement hydration on the millisecond timescale

Setting cement: highly dynamic hydration processes that occur during the first seconds of cement hydration were studied by time-resolved synchrotron X-ray diffraction. Polycarboxylate ether additives were found to influence the formation of the initial crystalline hydration products on a molecular level.     

Goldie Extending Modules

In this article, we define a module M to be 𝒢-extending if and only if for each X ≤ M there exists a direct summand D of M such that X ∩ D is essential in both X and D. We consider the decomposition theory for 𝒢-extending modules and give a characterization of the Abelian groups which are 𝒢-extending. In contrast to the charac-terization of extending Abelian groups, we obtain that all finitely generated Abelian groups are 𝒢-extending. We prove that a minimal cogenerator for 𝒢od-R is 𝒢-extending, but not, in general, extending. It is also shown that if M is (𝒢-) extending, then so is its rational hull. Examples are provided to illustrate and delimit the theory.     

The role of pulse time Toff on porous silicon as template for Au nanoparticles by using the integrated electrochemical technique

Gold nanoparticles (AuNPs) having variety of sizes and shape were prepared using the template synthesis approach. Porous silicon (PSi) was fabricated using the pulsed electrochemical anodization method at different pause times, T_off as template for gold deposition. Choosing suitable pulse parameter produces PSi with higher porosity and smaller crystallite size. SEM showed that the variation of T_off affects the pores formation and the growth of gold nanoparticles while EDX suggested the presence of Au inside the pores structure. Photoluminescence spectra showed emission enhancement and a blue shifted relative to porous silicon before deposited with AuNPs. XRD shows a high degree crystallinity of the samples and the presence of cubic gold with crystalline sizes was around 42 nm.     

Injection-seeded, gain-switched tunable Cr:ZnSe laser

We report a narrow-linewidth, tunable, gain-switched Cr:ZnSe laser operating between 2255 and 2455 nm. The spectral width of the laser was reduced from 125 nm to 0.3 nm by using injection seeding. Seeding was achieved with a second tunable CW Cr:ZnSe laser. The output wavelength was varied by tuning the wavelength of the seed laser. The seeded oscillator produced as high as 157 μJ pulses with 598 μJ incident pump pulse energy at a repetition rate of 1 kHz. The slope efficiency was determined to be 26%.     

Collective Perspective on Advances in Dyson-Schwinger Equation QCD

We survey contemporary studies of hadrons and strongly interacting quarks using QCD's Dyson-Schwinger equations, addressing the following aspects: confinement and dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and transition form factors, from small- to large-Q²; parton distribution functions; the physics of hadrons containing one or more heavy quarks; and properties of the quark gluon plasma.     

Investigation of the Interactions in Complexes of Low Molecular Weight Chitosan with Ibuprofen

Complexation between ibuprofen and low molecular weight chitosan (LMWC) was studied. LMWC was prepared from high molecular weight chitosan using the acid hydrolysis method. The complexes were investigated by using DSC, FT-IR and liquid-state ¹H-NMR. Molecular mechanics (MM) calculations were used to give insight into the stoichiometry of the interaction of chitosan with ibuprofen. The results showed that complexation of ibuprofen with LMWC involves ionic interaction between the ammonium group of LMWC and the carboxylate anion of ibuprofen. It was also shown that it is more efficient to prepare the complexes using lower concentration solutions of the polymer. These results were supported by molecular mechanics calculations. The experimental results may explain the discrepancies in the literature where, in many studies, the concentration of chitosan and its low average molecular weight were not considered to be important factors in the complexation process.