Introduction of Marinelli effective solid angles for correcting the calibration of NaI(Tl) field gamma-ray spectrometry in TL/OSL dating

A study is made of the corrections that are needed in the evaluation of the annual radiation dose, for use in TL/OSL-dating, via NaI(Tl) field gamma-ray spectrometry (monitoring of K, Th and U), calibrated via voluminous blocks that are simulating the Auger hole measuring conditions. Two cases are considered: the Heidelberg granite calibration block, which was found to be quasi-infinite, and the Oxford concrete calibration blocks, for which effective concentrations of elements are reported so as to account for their non-infiniteness. The calculations, via the software package ANGLE, are based on the concept of effective solid angles for Marinelli geometries.     

Electrometric titrations with a single polarised electrode Determination of hydrogen peroxide and manganese

A simple electrometric method for end-point detection, based on the lack of response of the indicator electrode in the titrated irreversible system has been described. The end-point is reached at the beginning of depolarisation of the electrode, when the equilibrium in the pre-balanced circuit is destroyed, producing an offbalance current.     

Thermal degradation of aliphatic hyperbranched polyesters and their derivatives

In this study results of thermal degradation of aliphatic hyperbranched polyesters, AHBP, and their derivatives, determined by non-isothermal thermogravimetric analysis in inert atmosphere (N₂) are presented. The thermal stability of linear polyester PHPA (polyhydroxypivalic acid), additionally synthesized from hydroxypivalic acid, was also studied. AHBP samples, from second to tenth pseudo-generation, were synthesized starting from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylolpropane. Modification of some selected AHBP samples was accomplished with the propionyl and benzoyl chloride, as well as with stearic acid. Thermal degradation of AHBP samples starts in the region between 250 °C and 275 °C and it ends around 430 °C. The thermal stability of AHBP samples increases with the number of end groups in the macromolecule, as well as with the modification of end groups with stearic acid and propionyl chloride. An AHBP sample of the fourth pseudo-generation, where all -OH end groups are modified with benzoyl chloride, shows lower thermal stability than the corresponding unmodified sample. The thermal stability of the linear polyester PHPA is lower than the thermal stability of the AHBP samples of the similar molar mass. The activation energies of thermal degradation for all synthesized AHBP samples were also calculated.     

Effect of aluminium on the radiochemical purity and99mTc-MDP biodistribution

Results on aluminium and^99mTc-MDP interaction under in vivo and in vitro conditions are presented. Aluminium, as chemical impurity, which in^99mTc-eluate some times appears above the allowed concentration (more than 20 g/ml) in the course of preparate labeling procedure may interact under in vitro conditions. Such a form of interaction was discovered by radiochromatographic methods. The highest Al³⁺-ion concentration studied (200 g/ml) increases the^99mTc-hydrolysate content by about ten times compared to the control. However, the same Al³⁺-ion concentration decreases by about four times the content of^99mTc-MDP complex, which is responsible for deposition in bones. According to biodistribution results obtained on wistar rats, significant increase of radioactivity in liver is observed, and at the same time the decrease in bones, in dependence on the aluminium ion dose. With a maximum dose of 200 g Al³⁺/kg b.w. the uptake of^99mTc-MDP in liver was higher for about 35% and lower in bones for 3.6%/g. With compensan (antacide drug) with which the animals were primarily treated per os, only considerably small changes were observed in^99mTc-MDP uptake, if compared to the control group. These findings are very important for clinical application of this preparate.     

ANGLE: A PC-code for semiconductor detector efficiency calculations

A broadly applicable, flexible and user-friendly PC-code (ANGLE) for calculations of semiconductor detector full energy peak efficiencies ( _p ) is presented. The physical model behind is the concept of the effective solid angle . Written in Pascal, and operating in windows and menus data manipulation mode, ANGLE yields the efficiencies for: (1) HPGe true- and closed-end coaxial (bothn- andp-types), (2) Ge(Li) open- and closed-end, (3) planar LEPD and (4) well-type detectors. Supposing coaxial positioning, cylindrical or Marinelli sources can be treated, regardless of their dimensions (this includes point, disk and ring sources, bulky samples and infinite geometrics). Possible displacement between source and detector axes is treated in our another work, relative to this one. ANGLE input parameters are: (1) reference efficiency curve for the detector used (i.e., efficiency vs. -energy for calibrated point sources at a reference distance), (2) detector type and configuration (active body and inactive layers, end cap, windows, housing, shielding, (3) source data (dimension and composition of both container and active material), (4) source-detector geometry (distance, intercepting layers and their composition) and (5) some computational data (Gauss integration coefficients). Gamma-attenuation is calculated upon an extensive (per element and per energy) data file. In the output, efficiency vs. -energy is found, both in forms of tables and graphs. In routine applications accuracies of 3–4% are achieved (not worse than 7% for the most unfavourable geometries). Computation times when using recent PC models are of the order of minutes. ANGLE frame is also easily adjustable to other semiempirical or Monte Carlo models for efficiency calculations.     

Probability of bystander effect per mSv induced by α-particle radiation

Radiation-induced bystander effect represents a paradigm shift in our understanding of the radiobiological effects of ionizing radiation in sense that they may also contribute to the final biological consequences of exposure to low doses of radiation. There exist the need to include the influence of the bystander effect in dosimetry of the human lung. The purpose of this work is to calculate the probability of bystander effect per one mSv, induced by α-particle radiation on sensitive cells of human lung. In this aim, a analytical model of cylinder bifurcation was created to simulate the geometry of human lung, with the distribution of cell in the airway wall of the tracheobronchial tree. This analytical model of the human tracheobronchial tree represents the extension of the ICRP66 model. Propagation of α-particle in human lung and airway tubes was simulated by Monte Carlo method. Calculations have been performed for the various source-target combinations. The results are given for two initial alpha particle energies (6 and 7.69 MeV) and two existing sources (fast and slow clearing mucus).     

Über die Einwirkung von Diazo-methan auf aromatische Ketone

Ohne Zusammenfassung     

Normal- and Reversed-Phase Behaviour of 16,17-Secoestrone Derivatives on Cyanopropyl-Bonded Silica Gel

The retention behaviour of a number of 16,17-secoestrone derivatives has been studied by LC and HPTLC on a polar cyanopropyl-bonded stationary phase using non-aqueous and aqueous-organic mobile phases. The retention behaviour has been discussed in terms of nature of the solute, eluent and stationary phase. The correlation between retention constants of 16,17-secoestrone derivatives obtained from reversed-phases and commercially available ACD log P software (Advanced Chemistry, Toronto, Canada) has also been examined.     

Kinetics of the substitution reactions of some Pt(II) complexes with 5′‐GMP and L‐histidine

The reactions of platinum(II) complexes, [PtCl₂(dach)] (dach = (1R,2R)‐1,2‐diaminocyclohexane) and [PtCl₂(en)] (en = ethylenediamine) with biologically relevant ligands such as 5′‐GMP (guanosine‐5′‐monophosphate) and l ‐His (l ‐histidine) were studied by UV–vis spectrophotometry, ¹H NMR spectroscopy, and high‐performance liquid chromatography (HPLC). Spectrophotometrically, these reactions were investigated under pseudo‐first‐order conditions at 310 K in 25 mM Hepes buffer (pH 7.2) and 10 mM NaCl to prevent the hydrolysis of the complexes. The [PtCl₂(en)] complex reacts faster than [PtCl₂(dach)] in the reaction with studied nucleophiles. This confirms the fact that the reactivity of studied Pt(II) complexes depends on the structure of the inert bidentate ligand. Also, the substitution reactions with l ‐His are always faster than the reactions with nucleotide 5′‐GMP. The reactions of [PtCl₂(dach)] and [PtCl₂(en)] complexes with l ‐histidine are studied by ¹H NMR spectroscopy. The obtained rate constants are in agreement with those obtained by UV–vis. The same reactions were studied by HPLC comparing the obtained chromatograms during the reaction. The changes in intensity of signals of the free and coordinated ligand show that after a few days there is only one dominant product in the system. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 43: 99–106, 2011     

Hamiltonization and Integrability of the Chaplygin Sphere in ℝ n

This paper studies a natural n-dimensional generalization of the classical nonholonomic Chaplygin sphere problem. We prove that for a specific choice of the inertia operator, the restriction of the generalized problem onto a zero value of the SO(n−1)-momentum mapping becomes an integrable Hamiltonian system after an appropriate time reparametrization.