Microstructure development of steel during severe plastic deformation

The microstructure development during plastic deformation was reviewed for iron and steel which were subjected to cold rolling or mechanical milling (MM) treatment, and the change in strengthening mechanism caused by the severe plastic deformation (SPD) was also discussed in terms of ultra grain refinement behavior. The microstructure of cold-rolled iron is characterized by a typical dislocation cell structure, where the strength can be explained by dislocation strengthening. It was confirmed that the increase in dislocation density by cold working is limited at 10¹⁶m⁻², which means the maximum hardness obtained by dislocation strengthening is HV3.7 GPa. However, the iron is abnormally work-hardened over the maximum dislocation strengthening by SPD of MM because of the ultra grain refinement caused by the SPD. In addition, impurity of carbon plays an important role in such grain refinement: the carbon addition leads to the formation of nano-crystallized structure in iron.     

Peroxiredoxin 2 as a chemotherapy responsiveness biomarker candidate in osteosarcoma revealed by proteomics

Purpose : We aimed to identify novel chemotherapy responsiveness biomarkers for osteosarcoma (OS) by investigating the global protein expression profile of 12 biopsy samples from OS patients. Experimental design : Six patients were classified as good responders and six as poor responders, according to the Huvos grading system. The protein expression profiles obtained by 2‐D DIGE consisted of 2250 protein spots. Results : Among them, we identified 55 protein spots whose intensity was significantly different (Bonferroni adjusted p‐value<0.01) between the two patient groups. Mass spectrometric protein identification demonstrated that the 55 spots corresponded to 38 distinct gene products including peroxiredoxin 2 (PRDX 2). Use of a specific antibody against PRDX 2 confirmed the differential expression of PRDX 2 between good and poor responders, while PRDX 2 levels as measured by Western blotting correlated highly with their corresponding 2‐D DIGE values. The predictive value of PRDX 2 expression was further confirmed by examining an additional four OS cases using Western blotting. Conclusions and clinical relevance : These results establish PRDX 2 as a candidate for chemotherapy responsiveness marker in OS. Measuring PRDX 2 in biopsy samples before treatment may contribute to more effective management of OS.     

Deformation-induced martensitic transformation behavior in cold-rolled and cold-drawn type 316 stainless steels

We investigate deformation-induced martensitic transformation behavior in cold-rolled and cold-drawn specimens of type 316 stainless steel. Deformation-induced martensite preferentially nucleates at the twin boundary between the austenite matrix and a deformation twin. In the cold-rolled specimen, martensite formed at the twin boundary has a Kurdjumov–Sachs (K–S) relationship with both the austenite matrix and the deformation twin (“double K–S relationship”). In the cold-drawn specimen, two kinds of deformation twins with different twin planes are typically formed, and therefore deformation-induced martensites are formed where the deformation twin boundaries intersect: martensite thus has an imperfect “triple K–S relationship” with the austenite matrix and the two deformation twins. The complicated crystallographic orientation relationship between austenite and martensite grains strongly restricts the formation of some variants of deformation-induced martensites. Because of the difference in number of nucleation sites in the cold-drawn and cold-rolled specimens, martensitic transformation is more enhanced in the former than in the latter.     

Interaction of Ag ions with a vanadium pentoxide hydrate—Formation of silver vanadate at low temperature

Reactions between V₂O₅·nH₂O sol and Ag⁺ solution were investigated and new conventional reaction processes to produce silver vanadate bronzes were found. Reactions were surveyed as a function of the concentration ratios of Ag and V, and the reaction regions were divided into 4 parts dependent upon the reaction products. System 1: ion-exchanged sediment to produce -Ag_0.35V₂O₅; System 2: needle-like -AgVO₃ and hydrate to produce Ag_{2 – x}V₄O₁₁ upon heating; System 3: new fine needle-like particle and small proportions of various dendrite crystallites; System 4: hydrate to produce -AgVO₃ upon heating. The new needle-like particle of system 3 was analyzed by use of electron diffraction and XRD and found to be monoclinic, a = 32.96 Å, b = 2.60 Å, c = 3.62 Å, and = 91.88°. The material is named -AgVO_3· -Ag_0.35V₂O₅ and Ag_{2 – x}V₄O₁₁ were reversibly crystallized after melt. -AgVO₃ was crystallized when the melt was cooled slowly, while -AgVO₃ was crystallized when quenched rapidly.     

Reactivity of layered vanadium pentoxide hydrate with ultrafine metal oxide, TiO2 and ZrO2, particles in an aqueous system

The interactions between vanadium pentoxide hydrate (V₂O₅·nH₂O) sol and colloid solutions of ultra fine titanium dioxide TiO₂ and zirconium dioxide particles ZrO₂ were studied. When mixed with an intrinsic V₂O₅·nnH₂O sol, TiO₂ particles in the mixed sol are sandwiched by V₂O₅·nH₂O layer sheets to form intercalation compounds. An Interlayer distance of V₂O₅·nH₂O was increased by this treatment and the surface area was also increased from 7.9 m² g^–1 for the V₂O₅·nH₂O to ca. 50 m² g^–1. When the TiO₂ sol was contacted with K-type V₂O₅·nH₂O, microporous nature appeared in the sample and the surface area incrased up to ca. 100 m² g^–1. The porous structure was maintained up to 300°C, above which materials were separated into two phases, anhydrous V₂O₅ and anatase type TiO₂. Ultrafine ZrO₂ particles were intercalated stoichiometrically in both intrinsic and K-type V₂O₅·nH₂O giving ZrO₂-V₂O₅·nH₂O for all the mixing ratios from ZrO₂/V₂O₅ = 5 to 20. Physico-chemical properties were almost unvaried and the materials were nonporous. Their surface areas are around 50 m² g^–1 for the former and around 60 m² g^–1 for the latter. The layered structure was maintained up to 300°C above which the sample was crystallized into ZrV₂O₇. The reaction temperature is about 150°C lower than that the heated mixture of ZrO₂ and V₂O₅ powders. The electron microscope observations of the prepared materials showed that the number of the stacked layers was decreased from more than 10 sheets for the sample before intercalation to about 2–4 sheets by exfoliation. This indicates that V₂O₅·nH₂O is exfoliated by ion exchangeably reacting to ultrafine titanium oxide and zirconium oxide particles.     

KOSI — An integrated system for discovering functional relations from databases

This paper describes an integrated system called KOSI (Knowledge Oriented Statistic Inference) for discovering functional relations from databases. The key feature of KOSI is that AI techniques and statistical methods are cooperatively used in the discovery process based on incipient hypothesis generation and evaluation, in which multi-search is performed in meta control. Two types of search, which use respectively different type of heuristics, are used inattribute calculation which is a kind of operation in which new attribute is generated as a function of the existing attributes. Third type of search, which is based on regression analysis, is mainly used for evaluating/selecting the best functional relation from the results of attribute calculation. Furthermore, a model-base and meta/domain knowledge are used for controlling the multi-search, and the methods of forming scopes/clusters can be used as a step of pre-processing before the search. KOSI is organized into multi-level structure for knowledge discovery and management efficiently. We try to provide a systematic manner of discovering functional relations, to support qualitative/quantitative discovery, and develop a more robust, general-purpose discovery system.     

Knowledge-based man-machine systems

A new method of increase user gain in man-machine interaction is discussed. In particular, attention is directed to describing a model in the computer. An intelligent system provided with the knowledge base and the inference mechanism is proposed for the purpose, whereby illustration is given of the system describing both structure and attributes of the real object in the same framework.