The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (−60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to ~70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α′ → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov–Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

     

Can organic farming help to reduce N-losses?

This study is in two parts. In the first part, nitrogen (N) losses per unit of milk and meat in Danish conventional and organic pig and dairy farming were compared on the basis of farm data. In the second part, organic and conventional dairy farming were compared in detail, using modelling. N-surpluses at different livestock densities, fodder intensities, and soil types were simulated. Finally, simulated N-surpluses were used in national scenarios for conversion to organic dairy farming in Denmark. In Part one, pig farming was found to have a higher N-efficiency than dairy farming. Organic pig production had a lower N-efficiency and a higher N-surplus per kg meat than conventional pig production. The possibilities to reduce N-loss by conversion to organic pig production therefore appear to be poor. Organic dairy farming had a higher N-efficiency and a lower N-surplus per kg milk than conventional dairy farming. Conversion from conventional to organic dairy farming may therefore reduce N-losses. In Part two, a positive correlation between livestock density and N-surplus ha^-1 was found for dairy farming. For all simulated livestock densities, fodder feeding intensities and soil types, organic systems showed a lower N-surplus per unit of milk produced than conventional systems. National scenarios for dairy farming showed that the present Danish milk production could be achieved with a 24% lower total N-surplus if converted from intensive conventional farming to extensive organic farming. At the same time, N-surplus ha^-1 and N-surplus (t milk)^-1 would be lowered by 50% and 25% respectively. Changing from intensive to extensive conventional dairy farming with a livestock density equal to that in the organic scenario resulted in a reduction in N-surplus ha^-1 of 15%. It was concluded that a reduction in total N-loss from agriculture is possible by converting from conventional to organic dairy farming but at the cost of either lower production on the present dairy farm area, or the current production on a substantially larger area.     

The Impact of a Ketogenic Diet and Liver Dysfunction on Serum Very Long-Chain Fatty Acids Levels

Peroxisomes play an essential role in mammalian cellular metabolism, particularly in oxidation fatty acid pathways. Serum very long-chain fatty acids (VLCFA), the main biochemical diagnostic parameters for peroxisomal disorders, were examined in 25 neurological patients with epilepsy on a ketogenic diet and 27 patients with liver dysfunction. The data show that patients on a ketogenic diet have increased levels of C22:0 and C24:0, but not C26:0, and normal C24:0/C22:0 and C26:0/C22:0. Patients with liver insufficiency showed a slightly elevated level of C26:0, a normal level of C24:0 and a decreased level of C22:0; thus in 21/27 the ratio of C24:0/C22:0 was increased and 15/27 the ratio of C26:0/C22:0 was increased.     

The effect of receptor-polymer matrix compatibility on properties of PEO-based polymer electrolytes containing a supramolecular additive: Part 1. Studies on phenomenon of compatibility

This paper presents the results of studies of poly(ethylene oxide)-based solid polymer electrolyte with the addition of anion receptor. The main stress is put on the influence of the anion receptor-polymeric matrix compatibility on the morphology of the composite. The comparison of the properties of two supramolecular compounds (calix[4]arene derivatives) having identical groups active in anion coordination in the narrow rim but with wide rim modified by groups having structure non-compatible and compatible to poly(ethylene oxide), is analyzed. The research of the system is made by means of vibrational (both IR and Raman) spectroscopies to evaluate the anion receptor-polymer–salt interactions. Raman and EDS mapping are used to determine the local concentration of the additive and salt. DSC and XRD determine the membrane crystallinity. Imaging techniques (both SEM and polarized light micrographs) allow to observe the morphology of membrane surface. The presented results show that additive distribution depends on the type of the receptor used and the phase of the polymer matrix (amorphous or crystalline).     

Superionic phase transition in Rb3D(SeO4)2 single crystals

Rb₃D(SeO₄)₂ belongs to the well-known group of hydrogen sulfate and selenate crystals which are promising for fuel cell applications. However, the high temperature properties of this salt have been much less extensively studied than those of Rb₃H(SeO₄)₂. Superionic phase transition in Rb₃D(SeO₄)₂ and Rb₃H(SeO₄)₂ single crystals was studied using impedance spectroscopy and DSC methods. Temperature evolution of the ferroelastic domain structure was observed under a polarizing microscope. Additionally, the X-ray diffraction and Raman scattering measurements for both crystals were carried out at room temperature. Rb₃D(SeO₄)₂ undergoes a structural phase transition from the low temperature ferroelastic phase to the superionic, paraelastic one. A correlation was found between the ferroelastic domains evolution, the anomalies of DSC and the temperature dependence of ionic conductivity. The temperature range of superionic phase transition in the first heating run was much wider and the T_S value was lower in Rb₃D(SeO₄)₂ than in the non-deuterated compound. Additionally, a considerable temperature hysteresis of T_S in Rb₃D(SeO₄)₂ was observed, unlike in Rb₃H(SeO₄)₂. The activation energies of H⁺ and D⁺ conductivity along the c-axis were found to be almost the same. The temperature variation of ionic conductivity in Rb₃D(SeO₄)₂ obtained in the first heating run of a virgin sample was found to differ considerably from that measured in subsequent cooling/heating runs. The small H/D isotope effect of proton conductivity in the crystals studied pointed to a classical activated diffusion mechanism.     

Tamoxifen and bone metabolism in postmenopausal low-risk breast cancer patients: a randomized study

PURPOSE: This trial was undertaken to evaluate the effect of adjuvant tamoxifen on bone metabolism in postmenopausal women undergoing surgery for low-risk breast cancer. PATIENTS AND METHODS: In an open trial, 25 women were randomized to receive tamoxifen 30 mg/d for 2 years, and 25 women constituted the control group. Twenty women treated with tamoxifen and 23 women in the control group provided data for the analysis. Inclusion criteria were operation for low-risk breast cancer and cessation of menstruations for more than 1 year. Exclusion criteria were presence of metastases, disorders of bone metabolism, contraindications against tamoxifen, use of drugs with influence on bone metabolism, ailments that made bone mineral measurements impossible, and age greater than 65 years. Repeated measurements of bone mineral density and content at the lumbar spine and forearms, serum alkaline phosphatase, phosphate, and ionized calcium were performed in all patients. RESULTS: Lumbar spine bone mineral density increased during the first year in women treated with tamoxifen and then stabilized, compared with decreased bone mineral density in the control group (P = .00074). Bone mineral content at the forearms remained almost stable in tamoxifen-treated women compared with a decrease in the control group (P = .024). Serum alkaline phosphatase, phosphate, and ionized calcium decreased in the tamoxifen group (P < .00001, P = .002, and P = .002, respectively). CONCLUSION: Tamoxifen has estrogen-like effects on bone metabolism that result in an increase and stabilization of bone mineral density in the axial skeleton and a stabilization of bone mineral content in the appendicular skeleton.     

Diffusional penetration during diffusion-induced grain-boundary migration process in an Al-Zn couple

The existence of diffusion-induced grain-boundary migration (DIGM) has been re-examined by electron probe micro analysis and analytical electron microscopy in the aluminium substrate of Al-Zn diffusion couple annealed in the temperature range 395–535 K. The investigation revealed two basic kinds of DIGM: laminar and turbulent. The laminar kind occurs over the whole temperature range and is characterized by a small migration distance and large migration depth. The zinc enrichment at a sample surface is 4.0–5.0 wt% and gradually decreases with increasing depth. The turbulent kind is limited to annealing temperatures above 450 K. In this case, the width of the alloyed zone is much greater, close to the surface of sample and then dramatically decreases, showing a behaviour similar to the laminar morphology. The zinc content at the surface of sample is 8.0–9.0 wt%. The diffusivities of DIGM calculated based on Cahn's equation agree well with the values of stationary grain boundary in diluted AlZn alloys. Evidence for the existence of DIGM was the asymmetry of the zinc profile with regard to the final position of the boundary. Microanalytical scan across the alloyed zone showed an abrupt change of the zinc concentration at the moving boundary. This suggests that the role of volume diffusion during DIGM is not so important and a considerable chemical contribution to the total driving force should exist.     

Case of Aperts'-Crouzon syndrome in a 6-year old boy

A congenital disorder syndrome defined by literature as the Alperts'-Crouzon has been described for a six-year-old boy. Introduction of this case seems to be justified noting the rarity of its occurrence.     

Effect of Pre- and Post-weld Heat Treatments on Linear Friction Welded Ti-5553

Linear friction welding allows solid-state joining of near-beta (β) titanium alloy Ti-5553 (Ti-5Al-5V-5Mo-3Cr). In the as-welded condition, the weld zone (WZ) exhibits β grain refinement and marked softening as compared with Ti-5553 in the solution heat treated and aged condition. The softening of the weldment is attributed to the depletion of the strengthening alpha (α) phase in the WZ and the adjacent thermo-mechanically affected zone (TMAZ). Specifically, in near-β titanium alloys, the strength of the material mainly depends on the shape, size, distribution, and fraction of the primary α and other decomposition products of the β phase. Hence, a combination of pre- and post-weld heat treatments were applied to determine the conditions that allow mitigating the α phase depletion in the WZ and TMAZ of the welds. The mechanical response of the welded samples to the heat treatments was determined by performing microhardness measurements and tensile testing at room temperature with an automated 3D deformation measurement system. It was found that though the joint efficiency in the as-welded condition was high (96 pct), strain localization and failure occurred in the TMAZ. The application of post-weld solution heat treatment with aging was effective in restoring α, increasing the joint efficiency (97 to 99 pct) and inducing strain localization and failure in the parent material region.     

Stochastic Analysis of Grain Drying with Unheated Air Under Two Different Climates

A stochastic analytical model of mass transfer was used to analyze processes of drying thin layers of grain ventilated with unheated air. As an excitation to the drying system, stochastic analytical models of variations in input air parameters during the post-harvest period of drying were used. Stochastic models were based on historical weather data of two different climates: the maritime climate of England, and the climate that is the mixture of continental and maritime climates. Changes in time of the mean and the standard deviation values of grain moisture content during drying were compared with statistical characteristics of input air parameters.