Vector analysis vs. regions of integration ratio method for determination of gamma and neutron contributions in a mixed field

The different ratios of the dosimetry peaks and the high temperature peaks after gamma and neutron irradiation can be employed for mixed field dosimetry, after performing proper analysis. In the present work the results obtained by the vector analysis method were compared to those obtained by the regions of integration (ROI) method for TLD600 chips irradiated by different combinations of gamma rays and thermal neutron doses. When applying the ROI method, the calculated neutron to gamma dose ratios (D_n/D_γ) were in good agreement (differences up to about 20%) with the actual experimental values in the D_n/D_γ range from 0.033 to 20. When applying the vector analysis method, the range of the D_n/D_γ ratio with differences up to about 20% is reduced to 0.033–4, and the uncertainties are generally higher. Thus, no advantage is expected when using the vector analysis method compared to the ROI method for evaluation of the dose ratio D_n/D_γ in a mixed field.     

Charmed hadrons in nuclear medium

We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner.We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions.We discuss the implications of the in-medium properties of open-charm mesons on the D s0 （2317） and the predicted X（3700） scalar resonances.     

Charmed hadrons in nuclear medium

We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss the implications of the in-medium properties of open-charm mesons on the DsO(2317) and the predicted X(3700) scalar resonances.     

Prediction of narrow N* and Λ* resonances with hidden charm above 4 GeV

The interaction between various charmed mesons and charmed baryons is studied within the framework of the coupled-channel unitary approach with the local hidden gauge formalism. Several meson-baryon dynamically generated narrow N* and Λ* resonances with hidden charm are predicted with mass above 4 GeV and width smaller than 100 MeV. The predicted new resonances definitely cannot be accommodated by quark models with three constituent quarks and can be looked for in the forthcoming PANDA/FAIR experiments.     

Synchrotron applications of an amorphous silicon flat‐panel detector

A GE Revolution 41RT flat‐panel detector (GE 41RT) from GE Healthcare (GE) has been in operation at the Advanced Photon Source for over two years. The detector has an active area of 41 cm × 41 cm with 200 µm × 200 µm pixel size. The nominal working photon energy is around 80 keV. The physical set‐up and utility software of the detector system are discussed in this article. The linearity of the detector response was measured at 80.7 keV. The memory effect of the detector element, called lag, was also measured at different exposure times and gain settings. The modulation transfer function was measured in terms of the line‐spread function using a 25 µm × 1 cm tungsten slit. The background (dark) signal, the signal that the detector will carry without exposure to X‐rays, was measured at three different gain settings and with exposure times of 1 ms to 15 s. The radial geometric flatness of the sensor panel was measured using the diffraction pattern from a CeO₂ powder standard. The large active area and fast data‐capturing rate, i.e. 8 frames s^?1 in radiography mode, 30 frames s^?1 in fluoroscopy mode, make the GE 41RT one of a kind and very versatile in synchrotron diffraction. The loading behavior of a Cu/Nb multilayer material is used to demonstrate the use of the detector in a strain–stress experiment. Data from the measurement of various samples, amorphous SiO₂ in particular, are presented to show the detector effectiveness in pair distribution function measurements.     

The challenge of optimizing expensive black boxes: a scatter search/rough set theory approach

There is renewed interest in the development of effective and efficient methods for optimizing models of which the optimizer has no structural knowledge. This is what in the literature is referred to as optimization of black boxes. In particular, we address the challenge of optimizing expensive black boxes, that is, those that require a significant computational effort to be evaluated. We describe the use of rough set theory within a scatter search framework, with the goal of identifying high-quality solutions with a limited number of objective function evaluations. The rough set strategies that we developed take advantage of the information provided by the best and diverse solutions found during the search, in order to define areas of the solution space that are promising for search intensification. We test our procedure on a set of 92 nonlinear multimodal functions of varied complexity and size and compare the results with a state-of-the-art procedure based on particle swarm optimization.     

Raman spectra and structure of a 25mer HCV RNA

We have employed Raman spectroscopy to investigate the conformation of an (Hepatitis C virus) HCV RNA 25mer (1–25 nucleotides) in solution. The principal findings of this study are (1) the A‐form secondary structure involving C3′‐ endo/anti ribofuranose pucker is predominant; (2) some uridine and guanosine nucleoside residues adopt the C2′‐ endo/anti and C3′‐ endo/syn conformations, respectively, which appear in looped nucleotide sequences; and (3) six out of nine guanine residues are base‐paired probably forming a stem. These results are interpreted as formation of a hairpin whose secondary structure is consistent with that proposed on the basis of phylogenetic comparisons with other viral RNAs. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel algorithm to solve the differential equation describing the non-interactive multiple-trap system model in thermoluminescence

The analysis of glow curves in thermoluminescence requires finding a closed expression for the light emitted as a function of the temperature and the parameters characterizing trap and recombination centers. Since it is not possible to derive a closed expression from the set of coupled differential equations describing the thermoluminescence phenomenon, approximations are made even for the simplest models. All of them resort to an approximation known as the quasi-equilibrium approximation (QE), and to further approximations. In this article, an algorithm is reported that permit the derivation of a closed expression for the emitted light for the model known as the non-interactive multi-trap system (NMTS) model by resorting only to the QE approximation. It is shown that the integration of the first order differential equation related to the NMTS model can be replaced by finding the roots of an analytical expression.     

Non‐Planar and Flexible Hole‐Transporting Materials from Bis‐Xanthene and Bis‐Thioxanthene Units for Perovskite Solar Cells

Two new hole‐transporting materials (HTMs), BX‐OMeTAD and BTX‐OMeTAD , based on xanthene and thioxanthene units, respectively, and bearing p‐methoxydiphenylamine peripheral groups, are presented for their use in perovskite solar cells (PSCs). The novelty of the newly designed molecules relies on the use of a single carbon‐carbon bond ‘C?C’ as a linker between the two functionalized heterocycles, which increases the flexibility of the molecule compared with the more rigid structure of the widely used HTM spiro‐OMeTAD. The new HTMs display a limited absorbance in the visible region, due to the lack of conjugation between the two molecular halves, and the chemical design used has a remarkably impact on the thermal properties when compared to spiro‐OMeTAD. BX‐OMeTAD and BTX‐OMeTAD have been tested in ([(FAPbI₃)_0.87(MAPbBr₃)_0.13]_0.92[CsPbI₃]_0.08)‐based PSC devices exhibiting power conversion efficiencies of 14.19 and 16.55 %, respectively. The efficiencies reached, although lower than those measured for spiro‐OMeTAD (19.63 %), are good enough to consider the chemical strategy used as an interesting via to design HTMs for PSCs.     

Ultra rapid freezing and vitrification of human embryos derived from abnormally fertilised zygotes

The present study was undertaken to compare the developmental capacity of human embryos derived from abnormally fertilised zygotes (1 PN, > 3 PN; 16-18 hours after ICSI) cryopreserved using two techniques: ultra rapid freezing and vitrification. At 2-4 cell stage, (48 hours after ICSI), these abnormally fertilised embryos were then distributed in three groups: a) embryos that were cryopreserved by ultra rapid freezing (URF Group), b) embryos cryopreserved by vitrification (V Group) and c) embryos that were not cryopreserved (Control group). Survival rates and embryo development after 24 hours of in vitro culture (72 hours after ICSI) were compared. 42 embryos were cryopreserved by ultra rapid freezing in 0.5 mL straws, using a mixture of dimethyl sulphoxide (3M) and sucrose (0.25M) in a base solution consisting of IVF medium plus 20 percent (v/v) of Human Serum Albumin (HSA), and 24 embryos were vitrified in 0.25 ml straws, using a two step protocol with an equilibration solution consisting of 10 percent ethylene glycol (1.79 M) and 10 percent dimethyl sulphoxide (1.41 M) in a base solution of modified phosphate buffered saline (PBS) with 20 percent of HSA and a vitrification solution consisting of 20 percent ethylene glycol (3.58 M), 20 percent dimethyl sulphoxide (2.82 M) and 0.5 M sucrose in base solution. The recovery rate after thawing/warming was lower for the vitrification group (75 percent V; 83 percent URF). The number of embryos with less than 50 percent of intact blastomeres after cryopreservation was significantly higher for the URF group (0 percent V; 34 percent URF). After in vitro culture, the rate of embryos not cryopreserved (Control group) that developed in vitro (72 hours after ICSI) was the highest (86 percent), followed by group V (50 percent), while group URF was the lowest (13 percent). These differences were statistically significant. This straw method of vitrification is successful and safe.