Evaluation of the enthalpy of formation, proton affinity, and gas-phase basicity of gamma-butyrolactone and 2-pyrrolidinone by isodesmic reactions

The knowledge of thermochemical parameters such as the enthalpy of formation, gas-phase basicity, and proton affinity may be the key to understanding molecular reactivity. The obtention of these thermochemical parameters by theoretical chemical models may be advantageous when experimental measurements are difficult to accomplish. The development of ab initio composite models represents a major advance in the obtention of these thermochemical parameters,. but these methods do not always lead to accurate values. Aiming at achieving a comparison between the ab initio models and the hybrid models based on the density functional theory (DFT), we have studied gamma-butyrolactone and 2-pyrrolidinone with a goal of obtaining high-quality thermochemical parameters using the composite chemical models G2, G2MP2, MP2, G3, CBS-Q, CBS-4, and CBS-QB3; the DFT methods B3LYP, B3P86, PW91PW91, mPW1PW, and B98; and the basis sets 6-31G(d), 6-31+G(d), 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p), 6-311G(d), 6-311+G(d), 6-311G(d,p), 6-311+G(d,p), 6-311++G(d,p), aug-cc-pVDZ, and aug-cc-pVTZ. Values obtained for the enthalpies of formation, proton affinity, and gas-phase basicity of the two target molecules were compared to the experimental data reported in the literature. The best results were achieved with the use of DFT models, and the B3LYP method led to the most accurate data.

Constancy check of beam quality in conventional diagnostic X-ray equipment

A tandem ionization chamber was developed for quality control programs of X-ray equipment used in conventional radiography and mammography. A methodology for the use of the tandem chamber in the constancy check of diagnostic X-ray beam qualities was established. The application at a medical X-ray imaging facility of this established methodology is presented. The use of the tandem chamber in the constancy check of diagnostic X-ray beam qualities is a useful method to control the performance of the X-ray equipment. (c) 2008 Elsevier Ltd. All rights reserved.

Thoracic aorta calcification detected by electron beam tomography predicts all-cause mortality

Background: The presence of coronary artery calcium (CAC) is an independent marker of increased risk of cardiovascular disease (CVD) events and mortality. However, the predictive value of thoracic aorta calcification (TAC), which can be additionally identified without further scanning during assessment of CAC, is unknown. Methods: We followed a cohort of 8401 asymptomatic individuals (mean age: 53 +/- 10 years, 69% men) undergoing cardiac risk factor evaluation and TAC and CAC testing with electron beam computed tomography. Multivariable Cox proportional hazards models were developed to predict all-cause mortality based on the presence of TAC. Results: During a median follow-up period of 5 years, 124 (1.5%) deaths were observed. Overall survival was 96.9% and 98.9% for those with and without detectable TAC, respectively (p < 0.0001). Compared to those with no TAC, the hazard ratio for mortality in the presence of TAC was 3.25 (95% CI: 2.28-4.65, p < 0.0001) in unadjusted analysis. After adjusting for age, gender, hypertension, dyslipidemia, diabetes mellitus, smoking and family history of premature coronary artery disease, and presence of CAC the relationship remained robust (HR 1.61, 95% CI: 1.10-2.27, p = 0.015). Likelihood ratio chi(2) statistics demonstrated that the addition of TAC contributed significantly in predicting mortality to traditional risk factors alone (chi(2) = 13.62, p = 0.002) as well as risk factors + CAC (chi(2) = 5.84, p = 0.02) models. Conclusion: In conclusion, the presence of TAC was associated with all-cause mortality in our study; this relationship was independent of conventional CVD risk factors as well as the presence of CAC. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Results of high dose-rate brachytherapy boost before 2D or 3D external beam irradiation for prostate cancer

Background and purpose: To evaluate biochemical control and treatment related toxicity of patients with localized adenocarcinoma of the prostate treated with high dose-rate brachytherapy (HDRB) combined with conventional 2D or 3D-conformal external beam irradiation (EBI). Material and methods: Four-hundred and three patients treated between December 2000 and March 2004. HDRB was delivered with three fractions of 5.5-7 Gy with a single implant, followed by 45 Gy delivered with 2D or 3D conformal EBI. Results: The median follow-up was 48.4 months. Biochemical failure (BF) occurred in 9.6% according to both ASTRO and Phoenix consensus criteria. Mean time to relapse was 13 and 26 months, respectively. The 5-year BF free survival using the ASTRO criteria was 94.3%, 86.9% and 86.6% for the low, intermediate and high risk groups, respectively; using Phoenix criteria, 92.4%, 88.0% and 85.3%, respectively. The only predictive factor of BF in the multivariate analysis by both ASTRO and Phoenix criteria was the presence of prostate nodules detected by digital palpation, and patients younger than 60 years presented a higher chance of failure using Phoenix criteria only. Conclusions: Treatment scheme is feasible and safe with good efficacy. (C) 2011 Elsevier Ireland Ltd All rights reserved. Radiotherapy and Oncology 98 (2011) 169-174

Determination of the force constant of a single-beam gradient trap by measurement of backscattered light

A single-beam gradient trap could potentially be used to hold a stylus for scanning force microscopy. With a view to development of this technique, we modeled the optical trap as a harmonic oscillator and therefore characterized it by its force constant. We measured force constants and resonant frequencies for 1-4-mu m-diameter polystyrene spheres in a single-beam gradient trap using measurements of back-scattered light. Force constants were determined with both Gaussian and doughnut laser modes, with powers of 3 and 1 mW, respectively. Typical values for spring constants were measured to be between 10(-6) and 4 x 10(-6) N/m. The resonant frequencies of trapped particles were measured to be between 1 and 10 kHz, and the rms amplitudes of oscillations were estimated to be around 40 nm. Our results confirm that the use of the doughnut mode for single-beam trapping is more efficient in the axial direction. (C) 1996 Optical Society of America.

Characterization of the Biocompatible Magnetic Colloid on the Basis of Fe(3)O(4) Nanoparticles Coated with Dextran, Used as Contrast Agent in Magnetic Resonance Imaging

The magnetic resonance imaging contrast agent, the so-called Endorem (TM) colloidal suspension on the basis of superparamagnetic iron oxide nanoparticles (mean diameter of 5.5 nm) coated with dextran, were characterized on the basis of several measurement techniques to determine the parameters of their most important physical and chemical properties. It is assumed that each nanoparticle is consisted of Fe(3)O(4) monodomain and it was observed that its oxidation to gamma-Fe(2)O(3) occurs at 253.1 degrees C. The Mossbauer spectroscopy have shown a superparamagnetic behavior of the magnetic nanoparticles. The Magnetic Resonance results show an increase of the relaxation times T(1), T(2), and T(2)* with decreasing concentration of iron oxide nanoparticles. The relaxation effects of SPIONs contrast agents are influenced by their local concentration as well as the applied field strength and the environment in which these agents interact with surrounding protons. The proton relaxation rates presented a linear behavior with concentration. The measured values of thermooptic coefficient partial derivative n/partial derivative T, thermal conductivity K, optical birefringence Delta n(0), nonlinear refractive index n(2), nonlinear absorption beta` and third-order nonlinear susceptibility vertical bar chi((3))vertical bar are also reported.

Proton transport model in the ionosphere .1. Multistream approach of the transport equations

The suprathermal particles, electrons and protons, coming from the magnetosphere and precipitating into the high-latitude atmosphere are an energy source of the Earth's ionosphere. They interact with ambient thermal gas through inelastic and elastic collisions. The physical quantities perturbed by these precipitations, such as the heating rate, the electron production rate, or the emission intensities, can be provided in solving the kinetic stationary Boltzmann equation. This equation yields particle fluxes as a function of altitude, energy, and pitch angle. While this equation has been solved through different ways for the electron transport and fully tested, the proton transport is more complicated. Because of charge-changing reactions, the latter is a set of two-coupled transport equations that must be solved: one for protons and the other for H atoms. We present here a new approach that solves the multistream proton/hydrogen transport equations encompassing the collision angular redistributions and the magnetic mirroring effect. In order to validate our model we discuss the energy conservation and we compare with another model under the same inputs and with rocket observations. The influence of the angular redistributions is discussed in a forthcoming paper.

Proton spectroscopy in Alzheimer`s disease and cognitive impairment no dementia: A community-based study

Objective: To describe the findings of proton magnetic resonance spectroscopy (H-1-MRS) in Alzheimer`s disease (AD) and cognitive impairment, no dementia (CIND) elderly from a community-based sample. Methods: Thirteen patients with AD, 12 with CIND and 15 normal individuals were evaluated. The H-1-MRS was performed in the right temporal, left parietal and medial occipital regions studying the metabolites N-acetylaspartate (NAA), creatine (Cr), choline (Cho) and myoinositol (ml). The clinical diagnosis was based on standardized cognitive tests - MMSE and CAMDEX - and the results correlated with the H-1-MRS. Results: Parietal Cho was higher in control individuals and lower in CIND subjects. AD and control groups were better identified by temporal and parietal ml combined with the temporal NAA/Cr ratio. CIND was better identified by parietal Cho. Conclusion: The H-1-MRS findings confirmed the hypothesis that metabolic alterations are present since the first symptoms of cognitively impaired elderly subjects. These results suggest that combining MRS from different cerebral regions can help in the diagnosis and follow-up of community elderly individuals with memory complaints and AD. Copyright (C) 2008 S. Karger AG, Basel.

Brazilian experience with two conditioning regimens in patients with multiple sclerosis: BEAM/horse ATG and CY/rabbit ATG

Studies have shown that autologous hematopoietic SCT (HSCT) can be used as an intensive immunosuppressive therapy to treat refractory patients and to prevent the progression of multiple sclerosis (MS). This is a prospective multicentric Brazilian MS trial comparing two conditioning regimens: BEAM/horse ATG and CY/rabbit ATG. Most (80.4%) of the 41 subjects in the study had the secondary progressive MS subtype and the mean age was 42 years. The baseline EDSS score in 58.5% of the subjects was 6.5 and 78% had a score of 6.0 or higher, respectively. The complication rate during the intra-transplantation period was 56% for all patients: 71.4% of the patients in the BEAM/hATG group and 40% in the CY/rATG group (P = 0.04). Three subjects (7.5%) died of cardiac toxicity, sepsis and alveolar hemorrhage, all of them in the BEAM/ATG group. EFS was 58.54% for a ll patients: 47% in the BEAM/hATG group and 70% in the CY/rATG group (P = 0.288). In conclusion, the CY/rATG regimen seems to be associated with similar outcome results, but presented less toxicity when compared with the BEAM/hATG regimen. Long-term follow-up would be required to fully assess the differences in therapeutic effectiveness between the two regimens. Bone Marrow Transplantation (2010) 45, 239-248; doi:10.1038/bmt.2009.127; published online 6 July 2009

In vivo dosimetry with thermoluminescent dosimeters in external photon beam radiotherapy

The ultimate check of the actual dose delivered to a patient in radiotherapy can only be achieved by using in vivo dosimetry. This work reports a pilot study to test the applicability of a thermoluminescent dosimetric system for performing in vivo entrance dose measurements in external photon beam radiotherapy. The measurements demonstrated the value of thermoluminescent dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in radiotherapy. (c) 2009 Elsevier Ltd. All rights reserved.

Detection of Horizontal Root Fracture with Small-volume Cone-Beam Computed Tomography in the Presence and Absence of Intracanal Metallic Post

Introduction: The aim of the present study was to test the accuracy of small-volume cone-beam computed tomography (CBCT) scanning in the detection of horizontal root fractures and to assess the influence of a metallic post. Methods: Forty teeth were divided into four groups based on the presence of metallic posts and horizontal root fracture. The teeth were examined by small-volume CBCT scanning at 0.2-mm voxel resolution. Three observers analyzed the samples for the presence of a horizontal root fracture. Sensitivity and specificity were calculated. Results: High values for accuracy (73%-88%) were obtained in the groups without a metallic post, and statistically significant differences were found when the group with a metallic post has been observed (55%-70%). Intraobserver agreement also showed statistically significant differences in the groups with a metallic post. Conclusions: Small-volume CBCT scanning showed high accuracy in detecting horizontal root fracture without a metallic post. However, the presence of a metallic post significantly reduced the specificity and sensitivity of this examination. (J Endod 2011;37:1456-1459)