Antioxidant vitamins and prevention of cardiovascular disease: Epidemiological and clinical trial data

Naturally occurring antioxidants such as vitamin E, β-carotene, and vitamin C can inhibit the oxidative modification of low density lipoproteins. This action could positively influence the atherosclerotic process and, as a consequence, the progression of coronary heart disease. A wealth of experimental studies provide a sound biological rationale for the mechanisms of action of antioxidants, whereas epidemiologic studies strongly sustain the “antioxidant hypothesis”. To date, however, clinical trials with β-carotene supplements have been disappointing, and their use as a preventive intervention for cancer and coronary heart disease should be discouraged. Only scanty data from clinical trials are available for vitamin C. As to vitamin E, discrepant results have been obtained by the Alpha-Tocopherol, Beta Carotene Cancer Prevention Study with a low-dose vitamin E supplementation (50 mg/d) and the Cambridge Heart Antioxidant Study (400–800 mg/d). The results of the GISSI-Prevenzione (300 mg/d) and HOPE (400 mg/d) trials suggest the absence of relevant clinical effects of vitamin E on the risk of cardiovascular events. Currently ongoing are several large-scale clinical trials that will help in clarifying the role of vitamin E in association with other antioxidants in the prevention of atherosclerotic coronary disease.     

Einfluss der Vakuumwärmebehandlung neuer Warmarbeitsstähle auf deren mechanische Eigenschaften und Verzug — Vergleich numerische Simulation mit Messung

Heat treatment simulation of high alloyed hot work tool steels — Analysis of the vacuum heat treatment process — Temperature measurement — Generation of material data of the individual phases and mathematical formulation of the phase transformations — Validation of the model on basis of several vacuum heat treatments with different hot work tool steels and different gas quenchings — Comparison of measured and calculated hardness distributions, residual stresses, changes in dimension und volume fraction of phases both in the hardened and in the tempered state — Influence of different gas quenchings on unnotched and notched impact energy (Charpy-V)     

Dead time-dependent line distortions in absolute-value electron spin echo envelope modulation spectra

The 30-base pair (bp) deletion of the cytoplasmic carboxy-terminal domain of the latent membrane protein 1 (LMP-1) gene was analyzed in 37 frozen tissues from patients with Epstein-Barr virus (EBV)-related gastric cancer and 18 throat washings from healthy adults in southern Japan. The 30-bp deletion was identified in 33 (91.7%) of 36 specimens of EBV-related gastric cancers and in 15 (83.3%) of 18 throat washings from healthy adults. In one case of gastric cancer, an additional 9-bp deletion was identified downstream of the 30-bp deletion. From the last transmembrane domain to the end of the carboxy terminal of LMP-1, mutations were examined in 37 cases of gastric cancers and in three cases of throat washings. Twenty-eight nonsilent mutations were identified in this region of EBV-related gastric cancer and throat washings. Five nonsilent mutations at positions 168,755, 168,746, 168,687, 168,357, and 168,355 were identified in all 30-bp-deleted cases of EBV-related gastric cancers and throat washings. However, these nonsilent mutations were not identified in three patients without the 30-bp deletion. Although the deletion and single-base mutations of the LMP-1 gene in gastric cancers and throat washings were similar to those of nasopharyngeal carcinoma in Taiwan and China, more single-base mutations were found in southern Japan. These data indicate that high prevalence of the 30-bp deletion of the LMP-1 gene in gastric cancers may reflect the prevalence of the deletion variant in the normal population in southern Japan.     

Crystallization of Rhenium Salts in a Simulated Low‐Activity Waste Borosilicate Glass

This study presents the characterization of salt phases that formed on simulated low‐activity waste glass melts during a rhenium solubility study. This study with rhenium salts is also applicable to real applications involving radioactive technetium salts. In this synthesis method, oxide glass powder is mixed with the volatile species, vacuum‐sealed in a fused quartz ampoule, and then heated in a furnace. This technique restricts the volatile species to the headspace above the melt but still within the sealed ampoule, thus maximizing the concentration of these species that are in contact with the glass. Above the previously determined solubility of Re⁷⁺ in this glass, a molten salt phase segregated to the top of the melt and crystallized into a solid layer. This salt was analyzed with X‐ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, as well as wavelength dispersive spectroscopy and was found to be composed of alkali perrhenates (NaReO₄, KReO₄) and alkali sulfates. Similar crystalline inclusions were found in the bulk of some glasses as well.     

Photon correlation spectroscopy on flowing polydisperse fluid-particle systems: theory

We develop an analytical expression for the homodyne autocorrelation function of laser light scattered by a laminar flow of a polydisperse particle-fluid system. In contrast to the already existing literature on the development of autocorrelation functions, we explicitly begin with the effects of the finite linewidth of the light source, the spatial and temporal intensity averaging that is due to the detection process, the Brownian particle movement on the amplitudes of the scattered light waves as well as on the degree of resolution that we introduce in this paper, and a general system velocity v = (v(x), v(y), v(z)). One main result is a new physical interpretation of the well-known, generally empirically introduced coherence factor. Quantities that are comparable to the well-known degree of coherence, coherence area, and number of coherence areas have also been obtained. Finally the investigations are simplified to an autocorrelation function that can be used for the analysis of fluid-particle systems in the low Knudsen number regime. It is shown that in this case particle size or size distribution, system velocity, and particle concentration can be obtained simultaneously. The developed autocorrelation function is related to frequently analyzed special cases and compared with expressions from the literature.     

Structural resonances in a coated sphere: investigation of the volume-averaged source function and resonance positions

Morphology-dependent resonances in a coated sphere are investigated by computation of the volumeaveraged source function obtained from Lorenz-Mie theory. Analytic expressions for the source function in absorbing and nonabsorbing spheres are given in a suitable form for computations. An advantage of the investigation of the source function is that core and shell contributions can be computed and examined independently. Furthermore the influences of the refractive index and the thickness of the outer layer on resonance positions and height are studied in detail. These influences are presented for the α(104) partial-wave example.     

Application of the finite-element method for the forward and inverse models in optical tomography

The development of an optical tomographic imaging system for biological tissue based on time-resolved near-infrared transillumination has received considerable interest recently. The reconstruction problem is ill posed because of scatter-dominated photon propagation, and hence it requires both an accurate and fast transport model and a robust solution convergence scheme. The iterative image recovery algorithm described in this paper uses a numerical finite-element solution to the diffusion equation as the photon propagation model. The model itself is used to compare the influence of absorbing and scattering inhomogeneities embedded in a homogeneous tissue sample on boundary measurements to estimate the possibility of separating absorption and scattering images. Images of absorbers and scatterers reconstructed from both mean-time-of-flight and logarithmic intensity data are presented. It is found that mean-time-of-flight data offer increased resolution for reconstructing the scattering coefficient, whereas intensity data are favorable for reconstructing absorption.     

Computational calibration method for optical tomography

We propose a computational calibration method for optical tomography. The model of the calibration scheme is based on the rotation symmetry of source and detector positions in the measurement setup. The relative amplitude losses and phase shifts at the optic fibers are modeled by complex-valued coupling coefficients. The coupling coefficients can be estimated when optical tomography data from a homogeneous and isotropic object are given. Once these coupling coefficients have been estimated, any data measured with the same measurement setup can be corrected for the relative variation in the data due to source and detector losses. The final calibration of the data for the source and detector losses and the source calibration between the data and the forward model are obtained as part of the initial estimation for reconstruction. The calibration method was tested with simulations and measurements. The results show that the coupling coefficients of the sources and detectors can be estimated with good accuracy. Furthermore, the results show that the method can significantly improve the quality of reconstructed images.     

Optical tomography in the presence of void regions

There is a growing interest in the use of near-infrared spectroscopy for the noninvasive determination of the oxygenation level within biological tissue. Stemming from this application, there has been further research in the use of this technique for obtaining tomographic images of the neonatal head, with the view of determining the levels of oxygenated and deoxygenated blood within the brain. Owing to computational complexity, methods used for numerical modeling of photon transfer within tissue have usually been limited to the diffusion approximation of the Boltzmann transport equation. The diffusion approximation, however, is not valid in regions of low scatter, such as the cerebrospinal fluid. Methods have been proposed for dealing with nonscattering regions within diffusing materials through the use of a radiosity-diffusion model. Currently, this new model assumes prior knowledge of the void region location; therefore it is instructive to examine the errors introduced in applying a simple diffusion-based reconstruction scheme in cases in which there exists a nonscattering region. We present reconstructed images of objects that contain a nonscattering region within a diffusive material. Here the forward data is calculated with the radiosity-diffusion model, and the inverse problem is solved with either the radiosity-diffusion model or the diffusion-only model. The reconstructed images show that even in the presence of only a thin nonscattering layer, a diffusion-only reconstruction will fail. When a radiosity-diffusion model is used for image reconstruction, together with a priori information about the position of the nonscattering region, the quality of the reconstructed image is considerably improved. The accuracy of the reconstructed images depends largely on the position of the anomaly with respect to the nonscattering region as well as the thickness of the nonscattering region.