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Abstract

Extreme ultraviolet (XUV) capillary-discharge lasers (CDLs) are a suitable source for the efficient, clean ablation of ionic crystals, which are obviously difficult to ablate with conventional, long-wavelength lasers. In the present study, a single crystal of cesium iodide (CsI) was irradiated by multiple, focused 1.5-ns pulses of 46.9-nm radiation delivered from a compact XUV-CDL device operated at either 2-Hz or 3-Hz repetition rates. The ablation rates were determined from the depth of the craters produced by the accumulation of laser pulses. Langmuir probes were used to diagnose the plasma plume produced by the focused XUV-CDL beam. Both the electron density and electron temperature were sufficiently high to confirm that ablation was the key process in the observed CsI removal. Moreover, a CsI thin film on MgO substrate was prepared by XUV pulsed laser deposition; a fraction of the film was detected by X-ray photoelectron spectroscopy.

Abstract

The aim of the present study is to compare dose distributions and their verification in target areas and organs at risk (OAR) in conformal and volumetric modulated arc therapy (VMAT) techniques. Proper verification procedures allow the removal of the major sources of errors, such as incorrect application of a planning system, its insufficient or cursory commissioning, as well as an erroneous interpretation of the obtained results. Three target areas (head and neck, chest, and pelvic) were selected and the treatment was delivered based on plans made using collapsed cone convolution and Monte Carlo algorithms with 6-MV photon beams, adopting conformal and VMAT techniques, respectively. All the plans were prepared for the anthropomorphic phantom. Dose measurements were performed with TL detectors made of LiF phosphor doped with magnesium and titanium (LiF:Mg,Ti). This paper presents the results of TL measurements and calculated doses, as well as their deviations from the treatment planning system (TPS) in the three planned target areas. It was established that the algorithms subject to analysis differ, particularly in dose calculations for highly inhomogeneous regions (OAR). Aside from the need to achieve the dose intended for the tumour, the choice of irradiation technique in teleradiotherapy should be dictated by the degree of exposure to individual critical organs during irradiation. While nothing deviated beyond the bounds of what is acceptable by international regulatory bodies in plans from TPS, clinically one must be more cautious with the OAR areas.

Abstract

The new vehicle scanning system Sowa has been developed in the National Centre for Nuclear Research. This innovative device is equipped with a 300 kV X-ray tube, U-shape imaging detector line, transport system, and fully shielded container. Sowa allows for a detailed inspection of the car and the detection of illegal transported items. This article presents the design, applied solutions, and achieved results of Sowa scanning system.

Abstract

The aim of this experimental work was to examine whether semiconductor photodetectors may be applied for the efficient reading of thermoluminescent dosimeter (TLD) signals. For this purpose, a series of experiments have been performed at the Department of Physics, Warsaw University of Technology, in cooperation with the Central Laboratory for Radiological Protection (CLOR). Specifically, the measurement system proposed here has been designed to detect a signal from TLDs that use a semiconductor detector operating in conditions analogous to those met when using commercial devices equipped with a classic photomultiplier. For the experimental tests, the TLDs were irradiated with a beam of 137Cs radiation in the accredited Laboratory for Calibration of Dosimetric and Radon Instruments. Eventually, a comparison of the results obtained with a semiconductor detector (ID120) and a commercial TLD reader with a photomultiplier tube (RADOS) were made.

Abstract

By considering energy-dependent form factors extracted from generalized Chou–Yang model, root mean square (rms) charge radii of deuteron and helium nuclei (alpha) are predicted at different values of center of mass energy which are in good agreement with theoretical predictions and experimental results. The rms radius is inversely proportional to mass of nuclei. Besides, the relationship between radii and energy are also derived.

Abstract

The solution behavior of beryllium halides and triflate in acetonitrile was studied by NMR, IR and Raman spectroscopy. Thereby mononuclear units [(MeCN)2BeX 2] (X = Cl, Br, I, OTf) were identified as dominant species in these solutions. The solid state structure of [(MeCN)2Be(OTf)2] has been determined by X-ray diffraction. If only one equivalent of MeCN is used the dinuclear compounds [(MeCN)BeX 2]2 (X = Cl, Br, I) are formed. Partial halide and triflate dissociation into the monomeric complexes as well as the formation of hetero-halide complexes [(MeCN)2BeClBr], [(MeCN)2BeClI] and [(MeCN)2BeBrI] was observed.

Abstract

Two new salts composed of the diprotonated 1,4-diazabicyclo[2.2.2]octane (DABCO) molecule as the cations and bromide and hydrogen oxalate as the anions have been isolated and structurally characterized by X-ray diffraction analysis. The salt [DABCOH2]{[HC2O4][Br]} (1) crystallizes in the orthorhombic system, space group P212121 with a = 9.0809(7), b = 9.5156(7), c = 12.3558(9) Å, V = 1067.67(14) Å3 and Z = 4. The salt [DABCOH2]2{[HC2O4][Br]3}·H2O (2) crystallizes in the orthorhombic system, space group Pnma with a = 26.6554(17), b = 7.3711(4), c = 10.7421(7) Å, V = 2110.6(2) Å3 and Z = 4. The compounds were prepared from ethanolic solutions of [DABCOH2][HC2O4]2 (L 1) and ZnBr2 in molar ratios of 2:1 and 1:1, respectively. The salts 1 and 2 exhibit extended hydrogen bonding networks leading to supramolecular topologies.

Abstract

Carbon subsulfide C3S2 can be produced on a preparative scale by flash vacuum pyrolysis (FVP). The precursor 5-(methylthio)-3H-1,2-dithiole-3-thione (C4H4S4) proved to be particularly suitable and yields up to 8% could be achieved on evaporation at T = 180 °C and pyrolysis of the vapour at 950 °C. The other precursors tested, C4S6 and C6S8, were far less productive. Insight into the thermal conversion of C4S6 was gained by isolation and structure determination of a new isomer of the sulur-carbon compound C8S8, which is formed on thermal treatment of C4S6 at T = 330 °C. The formation of C8S8 can be interpreted by sulfur cleavage from C4S6. Crystal growth by sublimation below 0 °C allowed for the determination of the crystal structure of C3S2. The five-atomic molecules are linear and arranged in a typical pattern analogous to the crystal structures of I2, CS2 and CSe2. The reaction of C3S2 with bromine is known to give C3Br6S2 of yet unknown structure. By sublimation of C3Br6S2 in air, 4,5-dibromo-1,2-dithiol-3-one (C3Br2OS2) was obtained, representing the product of bromine abstraction and oxidation. This substantiates the former suggestion for C3Br6S2 to have the structure of a hexabromodithiolane.

Abstract

The excited state properties of Pt(II) complexes are strongly influenced by their microenvironment and by intermolecular interactions. In this work, we investigated the photoluminescence of six Pt(II) complexes adsorbed onto a layered nanoclay, namely Laponite® (LAP). The excellent water dispersibility and gel-forming nature of the LAP was exploited to achieve a class of versatile materials. In particular, we report on the comparative photophysics of the dry powders and the hydrogels. Steady-state and time-resolved photoluminescence spectroscopy were used to assess the role of structural features at molecular level on the interaction between the nanodiscs, which in turn affects the intermolecular coupling of the coordination compounds in the excited state.