A 13-week subchronic toxicity study of josamycin in F344 rats

A 13-week subchronic toxicity study of josamycin was performed in male and female F344 rats to determine the maximum tolerable dose (MTD) for subsequent investigation of the carcinogenicity. As animals refused to take diet containing 5.0% josamycin in our preliminary study, dose levels in the present study were determined as 0, 0.16, 0.32, 0.63, 125 and 2.5% in diet. Rats were randomly allocated to 6 groups, each consisting of 10 males and 10 females. No animal died during the administration period and no group showed significant changes in body weight gain. Definite toxicity of josamycin was not noted in hematological and serum biochemical examinations. Histopathological examinations revealed no particular findings related to josamycin administration except cecal enlargement in the 1.25 and 2.5% groups. based on the results of the present study, it was concluded that the MTD of josamycin in 2.5% in diet, because the dietary dose level of 2.5% proved to exert no significant toxicological signs.     

Characterization of solid-phase welds between Ti---6A1---2Sn---4Zr---2Mo---0.1Si and Ti---13.5A1---21.5Nb titanium aluminide

Dissimilar-alloy welds have been produced between Ti---6Al---2Sn---Z4---2Mo---0.1Si (wt. %) and Ti---13.5Al---21.5 NB (wt.%) titanium aluminde using the three different solid-phase welding processes that create significantly different thermo-mechanical conditions at the weld interface. Exposure to supertransus temperatures, appreciable deformation and rapid cooling of the weld interface region during linear-friction welding promote dynamic recrystallization of beta grains and beta decomposition to fine martensitic products. In contrast, diffusion welding at temperatures below the base metal beta transus temperatures and at relatively low pressures minimizes deformation and microstructural variations in the weld interface region relative to the unaffected base metal. During capacitor-discharge resistance spot welding, extremely rapid heating of the weld interface region to near-solidus temperatures, and subsequent rapid cooling, result in the formation of a metastable, ordered-beta microstructure in the Ti---s13.5Al---21.6Nb and fine alpha-prime martensite in the Ti---6Al---2Sn---4Zr---2Mo-0.1Si.     

US trends in nutrient intake: the 1987 and 1992 National Health Interview Surveys

OBJECTIVES: This study examined US trends in nutrient intake, using almost identical methods and nutrient databases in two time periods. METHODS: An extensive dietary intake questionnaire was included in supplements to the 1987 and 1992 National Health Interview Surveys. Dietary data from approximately 11,000 persons in each of those years were analyzed. RESULTS: The total and saturated fat intake and the percentage of energy from fat declined among Whites and Hispanics, but only minimal changes were seen in Black Americans. The changes in fat intake were attributable principally to behavioral changes in frequency and type of fat-containing foods consumed rather than to the increased availability of leaner cuts of meat. Dietary cholesterol showed one of the largest declines of the nutrients examined. Less desirable changes were also seen. Cereal fortification played an important role in the observed changes in several micronutrients. CONCLUSIONS: Educational campaigns on dietary fat and cholesterol have been moderately effective, but not in all racial/ethnic groups. Future campaigns should emphasize maintaining or increasing micronutrient intake.     

Solution and applications of the Lyapunov equation for controlsystems

Recent advances in control systems analysis and design have implied new uses for the Lyapunov equation of the form AX+XA^T+Q=0. Implementation requirements for the incorporation of the use of Lyapunov equations in practical design, however, point out the need for a set of specialized numerical procedures. This special set of numerical procedures must efficiently solve large, sparse Lyapunov equations, solve sets of Lyapunov equations that differ only in the coefficient matrix Q, and provide good low rank estimates of the Lyapunov equation solution X in the case where low rank approximations are applicable. Discussions of the motivations for the solution of these problems and of candidate solution approaches are provided     

The Heat Capacity of 4He Monolayers Adsorbed on Evaporated Gold

The specific heat of ⁴He condensed on an evaporated gold surface has been measured for coverages between 0.007 and 0.096 Å^?2 and temperatures between 0.4 and 3.0 K. There are at least two types of physisorption site on the gold surface with binding energies ?83 ± 7 and ?94 ± 7 K. For coverages below 0.06 Å^?2 (～0.5 monolayers), the ⁴He is a two-dimensional classical gas at sufficiently high temperatures. At lower temperatures and higher coverages, the ⁴He forms condensed phases, including liquids, solids commensurate with the gold lattice, and incommensurate solids. The phase diagram of ⁴He/evaporated gold is similar to that for ⁴He/graphite, but the phase boundaries are shifted and not well defined, nor is the diagram as rich in structure.     

Cooling condition dependence on ion etching rate in a softmagnetic metallic glass

Taking into consideration the knock-on cascade mechanism and the free volume theory, the cooling condition dependentR _s (ion etching rate) is investigated for a liquid-quenched Fe-10at%Si-15at%B alloy glass. A highR _s is found in a slow cooled glass.     

The oxidative inducation test applied to medical PVC and other polymers

We have examined the applicability of this simple and effective test to polymer systems widely used in the medical industry. First, it was found that not every polymer examined exhibited a distinct onset of autocatalytic oxidation detectable by DSC. However, for cases where distinct onsets are found, powerful insights can be obtained. These included activation energy of the degradation, thermal oxidative shelf life prediction, and correlation, with product performances. Actual examples are presented to illustrate the utility of the test.     

Intergranular stresses in ZIRCALOY-2

The development of the understanding of the intergranular stresses in ZIRCALOY-2 is reviewed. Neutron diffraction measurements of the intergranular strains were made on rod-textured material and highly textured plate. The elastoplastic self-consistent (EPSC) model provides a sound theoretical foundation for our understanding of the behavior. The strain response of ZIRCALOY-2 to applied tensile stress is well described for two very different textures with the same slip and hardening parameters. It is almost certain that tensile twinning is the explanation for the response to compressive stress and rolling that is, as yet, incompletely understood. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.