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Scientific exploration of phototrophic bacteria over nearly 200 years has revealed large phylogenetic gaps between known phototrophic groups that limit understanding of how phototrophy evolved and diversified1,2. Here, through Boreal Shield lake water incubations, we cultivated an anoxygenic phototrophic bacterium from a previously unknown order within the Chloroflexota phylum that represents a highly novel transition form in the evolution of photosynthesis. Unlike all other known phototrophs, this bacterium uses a type I reaction centre (RCI) for light energy conversion yet belongs to the same bacterial phylum as organisms that use a type II reaction centre (RCII) for phototrophy. Using physiological, phylogenomic and environmental metatranscriptomic data, we demonstrate active RCI-utilizing metabolism by the strain alongside usage of chlorosomes3and bacteriochlorophylls4related to those of RCII-utilizing Chloroflexota members. Despite using different reaction centres, our phylogenomic data provide strong evidence that RCI-utilizing and RCII-utilizing Chloroflexia members inherited phototrophy from a most recent common phototrophic ancestor. The Chloroflexota phylum preserves an evolutionary record of the use of contrasting phototrophic modes among genetically related bacteria, giving new context for exploring the diversification of phototrophy on Earth.

Aquatic environments with high levels of dissolved ferrous iron and low levels of sulfate serve as an important systems for exploring biogeochemical processes relevant to the early Earth. Boreal Shield lakes, which number in the tens of millions globally, commonly develop seasonally anoxic waters that become iron rich and sulfate poor, yet the iron–sulfur microbiology of these systems has been poorly examined. Here we use genome-resolved metagenomics and enrichment cultivation to explore the metabolic diversity and ecology of anoxygenic photosynthesis and iron/sulfur cycling in the anoxic water columns of three Boreal Shield lakes. We recovered four high-completeness and low-contamination draft genome bins assigned to the class Chlorobia(formerly phylum Chlorobi) from environmental metagenome data and enriched two novel sulfide-oxidizing species, also from the Chlorobia. The sequenced genomes of both enriched species, including the novel “CandidatusChlorobium canadense”, encoded the cyc2gene that is associated with photoferrotrophy among cultured Chlorobiamembers, along with genes for phototrophic sulfide oxidation. One environmental genome bin also encoded cyc2. Despite the presence of cyc2in the corresponding draft genome, we were unable to induce photoferrotrophy in “Ca. Chlorobium canadense”. Genomic potential for phototrophic sulfide oxidation was more commonly detected than cyc2among environmental genome bins of Chlorobia, and metagenome and cultivation data suggested the potential for cryptic sulfur cycling to fuel sulfide-based growth. Overall, our results provide an important basis for further probing the functional role of cyc2and indicate that anoxygenic photoautotrophs in Boreal Shield lakes could have underexplored photophysiology pertinent to understanding Earth’s early microbial communities.

Hydroxyapatite (HA) coating was carried out by plasma spraying on bulk Ti substrates and porous Ti substrates having a Young’s modulus similar to that of human bone. The microstructures and bond strengths of HA coatings were investigated in this study. The HA coatings with thickness of 200–250 µ m were free from cracks at interfaces between the coating and Ti substrates. XRD analysis revealed that the HA powder used for plasma spraying had a highly crystallized apatite structure, while the HA coating contained several phases other than HA. The bond strength between the HA coating and the Ti substrates evaluated by standard bonding test (ASTM C633-01) were strongly affected by the failure behavior of the HA coating. A mechanism to explain the failure is discussed in terms of surface roughness of the plasma-sprayed HA coatings on the bulk and porous Ti substrates.

Fetal human liver cell fractions, which contain large numbers of hepatocyte progenitors, have high proliferation potential in vitro. To create an engineered liver tissue equivalent of a clinically significant size, however, repeated subcultivation and functional maturation are necessary in vitro. A commercially available human fetal liver cell fraction that was cultivated for some time in vitro has been reported to lose liver specific functions almost completely. We therefore investigated the effects of oncostatin M (OSM) and hepatocyte growth factor (HGF) in long term three-dimensional (3D) culture using macroporous poly-L-lactic acid (PLLA) scaffolds on the restoration of such liver-specific functions of the fraction.3D culture using PLLA scaffolds with OSM remarkably enhanced the albumin production and cytochrome P450 1A1/2 capacity with the culture time. HGF alone had no preferable effect on these functions even in 3D culture. a-fetoprotein production was consistently suppressed in the 3D culture compared with that in monolayers. This suppression was not observed in the same types of culture of hepatocarcinoma Hep G2 cells.Despite these favorable observations on the 3D culture with OSM, the final attained functional levels at the 5th week were still over ten-times lower than those of Hep G2 cells when standardized with a cellular DNA amount. Although further improvement is needed for the complete functional restoration and maturation in vitro, these results demonstrate that a combination of 3D culture using PLLA scaffolds and OSM offers promising culture conditions for in vitro maturation of human hepatocyte progenitors.

We have investigated the high-temperature solid-solution strengthening by oxygen in Nb, Nb–Ta and Nb–Mo single crystals by compression tests with constant strain rate. Nb, Nb–20Ta, Nb–40Ta, Nb–20Mo, and Nb–40Mo single crystals with various O content were grown by use of the electron-beam floating zone melting method. It is found that Nb and Nb–Ta single crystals are strengthened by oxygen at temperatures below 1100 K, while Nb–20Mo single crystals are strengthened even at 1473 K. The critical resolved shear stress (c.r.s.s.) of Nb–Ta single crystals at 298 K increases linearly with increasing O content, irrespective of Ta content. Furthermore, the increment of c.r.s.s. of Nb–Ta single crystals is larger than that of Nb. The c.r.s.s. of Nb-Mo single crystals is higher than that of Nb for all temperatures tested, and the c.r.s.s. of Nb–20Mo single crystals also increases with increasing O content. These results indicate that the interstitial–substitutional (i–s) interaction between O and Ta or Mo affects the mechanical properties in the Nb-based alloys at high temperature.

Off-stoichiometric Fe3Si single crystals with compositions of Fe–14at%Si and Fe–18at%Si were tensile tested at 973–1223 K and at various strain rates in order to investigate a mechanism for large elongation in coarse-grained Fe3Si polycrystals at elevated temperatures. Maximum elongation over 150% is attained for both the single crystals. 〈111〉 slip is dominantly operative in Fe–14at%Si with B2-ordered structure, while 〈001〉 is in Fe–18at%Si with D03-ordered structure. The mvalues indicating strain rate sensitivity are between 0.33 and 0.23 depending on orientation and temperature. Dynamic recrystallization is not occurring on large uniform elongation. The large elongation in the single crystals is attributable to a large mvalue around 0.3, which is not necessarily related to a solute-drag controlled creep mechanism, but to dislocation interactions accompanied with subgrain formation.

We have examined the expression of P-glycoprotein (P-gp) in adult T- cell leukemia (ATL) samples from 25 patients. Based on immunoblotting with a monoclonal antibody against P-gp, C219, 8 of 20 ATL patients were P-gp positive at the initial presentation. All 6 patients at the relapsed stage were P-gp positive, and refractory to chemotherapy. The expression of MDR1 mRNA in P-gp-positive ATL cells was increased at the relapsed stage of one patient. P-gp of this patient was photolabeled with [3H]azidopine and the labeling was inhibited with nimodipine, vinblastine and progesterone. These results suggest that P-gp expressed in ATL cells from patients at relapsed stage has the same binding site(s) for the drugs as that in multidrug resistant cells, and is correlated with the refractory nature of the cells to chemotherapy.

To determine whether or not presynaptic gamma-aminobutyric acid (GABA) receptors regulate the release of GABA, we examined properties of the presynaptic GABA receptor and compared the findings within the case of the postsynaptic GABA receptor, using the longitudinal muscle with myenteric plexus (L-M) preparation of guinea pig small intestine. Muscimol, but not baclofen, reduced the Ca++-dependent release of [3H]GABA evoked by high K+ in the presence of tetrodotoxin from L-M preparation of the small intestine preloaded with [3H]GABA. Bicuculline, picrotoxin and furosemide antagonized the effect of muscimol. Diazepam, clonazepam and pentobarbital potentiated the muscimol-induced inhibition of high K+-evoked release of [3H]GABA. The potentiating effect of clonazepam was antagonized by Ro 15-1788. Muscimol induced a Ca++-dependent and tetrodotoxin-sensitive release of [3H]acetylcholine from L-M preparation preloaded with [3H]choline. The effect of muscimol was antagonized by bicuculline, picrotoxin and furosemide. Diazepam, clonazepam and pentobarbital potentiated the muscimol-evoked release of [3H]ACh. The potentiation of muscimol effect by clonazepam was inhibited by Ro 15-1788. These results indicate that both the GABA autoreceptor and postsynaptic receptor may possess the same property which is related to benzodiazepine and barbiturate binding sites in the enteric nervous system of the guinea pig small intestine. The benzodiazepine binding site seems to be of central type.

Microstructures in a commercial Nb-Ti alloy heat-treated or repeatedly aged and cold worked have been investigated by transmission electron microscopy. In the aged samples after solution treatment,?-phase forms at ageing temperatures below 673 K anda-phase precipitates at 773 K. Cold work after solution treatment or heavy cold work without prior solution treatment results in accelerated precipitation of?-phase on ageing at 623 K and ofa-phase on ageing at 773 K, while it givesa-precipitation instead of? on ageing at 673 K. Repeated ageing and cold work make the microstructures very fine. The refinement is due to formation of dislocation cell structures and subgrains and precipitation of?- anda-phases.

Deformation behaviour of the recrystallized Ni3AI with non-stoichiometric and stoichiometric compositions have been investigated. Recrystallization microstructures in non-stoichiometric Ni3AI are composed of the Ll2 ordered ?' and a small amount of the f c c disordered ?. It is shown that the large elongation of non-stoichiometric Ni3AI is due to ?-phase existing at recrystallized ?t'-?' grain boundaries. Recrystallization microstructures in stoichiometric Ni3AI are confirmed to be a single phase of ?'. Coarse-grained stoichiometric Ni3AI shows considerable ductility, although the fine-grained compound is brittle. The ductility may be related to the low yield strength in the coarse-grained samples.

High-temperature compression tests were performed in air for YBa2Cu3O7-x polycrystals with grain sizes of 3 and 7 ?m at various strain rates between 1.3×10-5 and 4×10-4s-1 and at temperatures between 1136 and 1253 K. Steady state deformation appeared above 1203 K for both samples. A stress exponent of 1.3 and an activation energy of 150 kJ mol-1 were evaluated. The compression tests and microstructural observations revealed that there was a difference in deformation mechanism above and below 1203 K. The dominant mechanism was diffusional creep associated with grain-boundary sliding above 1203 K, and dislocation glide accompanied with grain-boundary sliding below 1203 K. The growth of anisotropic grains and their preferred arrangement were enhanced by deformation.

Our studies on lattice defects and strength anomaly in B2 FeAl are reviewed in this paper, including our latest results. Influence of excess vacancies introduced by quenching from an elevated temperature is very important to the mechanical properties of B2 FeAl. Dot-like features and very small dislocation loops, probably formed by the interaction between gliding dislocations and excess vacancy clusters, were observed on the traces of dislocation movement in a thin foil of a water-quenched specimen. It is considered that the formation process of these dot-like features and small loops is closely associated with an excess-vacancy strengthening mechanism. Positive temperature dependence of yield stress is one of the hottest topics in B2 FeAl. It has been revealed by strain-rate change tests and stress relaxation tests that a recovery rate increases with increasing temperature in the range where temperature dependence of yield stress is positive (Stage II). It was observed in TEM that many superlattice dislocations had climb-dissociated configurations in Stage II, and that 〈111〉-type dislocations were predominant even at the peak temperature when a specimen was deformed to a small strain. Based on these results, the climb-dissociation locking is believed to be the major cause for the strength anomaly.

A monoclonal antibody, FTF 148, was prepared by hybridizing murine myelomal cells (NS-1) and spleen cells of BALB/c mice immunized with cultured cells derived from an adult T cell leukemia (ATL) patient (KUT- 2 cells). This monoclonal antibody reacted with all of the human T cell leukemia virus I (HTLV-I)-infected cell lines tested but did not react with other T cell lines derived from acute lymphocytic leukemia, Epstein-Barr virus-transformed B cell lines, or an erythroleukemic cell line. This monoclonal antibody was not directed to viral antigens because it reacted equally well with almost all KUT-2 and MT-1 cells, only 1% to 3% of which were ATL-associated antigen-positive. In contrast to interleukin 2 receptors expressed on both ATL cells and normal phytohemagglutinin-stimulated blasts, this antigen was not expressed on the latter cells. The antigen, mainly expressed on the cell membrane, was analyzed by metabolic labeling with 3H-leucine and surface labeling with 125I followed by cell lysis and immunoprecipitation with the FTF 148 antibody. The findings obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that p50 and p74 proteins were specifically precipitated and the antigen was also different from the product of the Xs gene of HTLV-I.

Plastic deformation mode and its relation to tensile properties were investigated in retainedß phase ofß-eutectoid type Ti-Cr alloys. A plate-like single variant? phase is induced during deformation of the most unstableß phase having a minimum chromium content required to suppress martensitic transformation. A selected area electron diffraction pattern taken from a boundary region of the stress-induced? phase plate can be explained by the idea that a single variant of? phase is induced in a {3 3 2} <1 1 3> twin produced during deformation. Anisotropy in population of four? phase variants decreases with increasing chromium content. On further increasing chromium content, deformation occurs by slip. Enhanced ductility is obtained in as-quenched Ti-Cr alloys accompanied by? phase transformation or {332} <1 1 3> twinning during deformation,? phase of as-quenched Ti-Cr alloys changes continuously from commensurate structure with sharp reflections to incommensurate structure with diffuse reflections with increasing chromium content. The obtained results inß-eutectoid type Ti-Cr alloys are quite similar to those inß-isomorphous type Ti-V alloys.

Plastic deformation mode ofß-eutectoid Ti-Fe alloys has been investigated at 300 and 77 K in a retainedß single phase (containing athermal ? phase). Surface analysis and transmission electron microscopy show that {332}<1 1 3> twinning and <1 1 1> slip appear to be dependent on orientation, composition and deformation temperature. The {3 3 2} <1 1 3> twinning appears only in metastableß regions adjacent to the Ms curve in good agreement with previous work inß-isomorphous alloys. Orientation dependence for occurrence of the preferential {332} <1 1 3> twinning among the twelve equivalent twinning systems can be explained in terms of the Schmid factor and the polarization of twinning shear. It is concluded that the {332} <1 1 3> twinning is common forß-titanium alloys and related to the instability of theß phase.

A microprocessor-based monitoring and control system for power system stability is described in this paper. A new method for monitoring and controlling the stability condition of the generator and system using the measured airgap fluxes has been developed and implemented on a microprocessor system. In order to check the validity of the proposed system, experimental investigation were performed on a laboratory-model power system. Problems encountered throughout the experiments are also discussed.

At the peak temperature, 823K, of the yield strength anomaly of B2 FeAl, slip band propagation and slip vector transition were investigated using Fe–39mol% Al single crystals. The single crystal oriented along a compression axis close to the [123]direction showed serrated flow during work-hardening at small strains (<2%). Coarse slip bands propagate in the single crystal specimens, like Lüders band propagation in polycrystals, in the initial strain range. The slip vector was identified by TEM to be parallel to 〈111〉 in the early stage of strain corresponding to yielding. Beyond plastic strains of about 3%, serrations disappeared and significant work-softening occurred. The slip vector responsible for the later stage of deformation was observed to be 〈100〉. That is, the slip vector changes from 〈111〉 to 〈100〉 as the plastic strain increases. Because the density of 〈111〉 superdislocations is found to be very low after the slip transition, glide decomposition of 〈111〉 superdislocations is believed to the primary source mechanism for 〈100〉 dislocations. The slip band propagation in B2 single crystals is discussed in comparison with that of other intermetallic single-crystalline materials.

A large tensile elongation reaching 180% is observed in Fe3Si single crystal with the B2 structure at temperatures of 0.65–0.74Tm, and at initial strain rates of 10−4–10−3/s. The large tensile elongation takes place at a steadily increased flow stress with increasing strain. The mechanical parameters evaluated for a constitutive equation show that the strain rate sensitivity is as large as 0.38 and the apparent activation energy ranges from 230 to 280kJ/mol. The deformation microstructure responsible for the large tensile elongation consists of subgrain microstructure, and indicates that glide and climb motions of the 〈111〉-type dislocations are concomitantly operating. It is suggested that comparable work hardening (by the glide motion of dislocations) with the dynamic recovery (by the climb motion of dislocations) takes place, and leads to a steadily increased flow stress and a favorable value of strain rate sensitivity, resulting in large plastic elongation and high fracture resistance.

Serum tumor necrosis factor-beta (TNF-beta) from patients with adult T- cell leukemia (ATL) was studied by a sandwich enzyme-linked immunosorbent assay (ELISA) developed in our laboratory using biotinylated monoclonal anti-TNF-beta and recombinant TNF-beta. Seven of eight patients with hypercalcemia showed elevation of serum TNF- beta. On the other hand, TNF-beta could not be detected by the ELISA in 28 patients without hypercalcemia. The lower detection limit in this assay was 100 pg/mL, corresponding to 500 pg/mL by the conventional method. In two patients serum TNF-beta level decreased after treatment in association with the level of serum calcium. Furthermore, immuno- staining using anti-TNF-beta and avidin-biotin complex showed the presence of cytoplasmic TNF-beta in not only human T-cell leukemia virus type I infected cell lines, but also freshly isolated cells from ATL patients with hypercalcemia. The actual biologic activity of TNF- beta in serum was confirmed by a conventional bioassay in a patient with hypercalcemia, and its cytotoxic activity was inhibited by the addition of anti-TNF-beta antibody in the assay. These results suggested that serum TNF-beta might be one of the factors contributing to the hypercalcemia, at least in patients with ATL.

Abstract The purpose of this study was to clarify the clinical efficacy of multidrug chemotherapy for aggressive adult T-cell leukemia (ATL). We report the therapeutic results of treatment of patients with aggressive ATL undertaken between 1986 and 1995. A total of 120 newly diagnosed patients with a performance status of 0-3 and aged &lt;70 years at diagnosis were entered into the study. Clinical features, including clinical subtypes, serum levels of lactate dehydrogenase and blood urea nitrogen, the response to chemotherapy, and doses of individual chemotherapeutic agents, were evaluated. Of the 120 patients enrolled, 97 had acute-type and 23 lymphoma-type ATL. The complete response rate and median survival of these patients were 25.3% and 9 months, respectively. The 2- and 5-year survival rates were 18.4% and 8%, respectively, and five patients have been alive for >5 years and are disease-free. These long-term survivors had good prognostic factors at diagnosis. There was no correlation between the doses of the various chemotherapeutic agents and the survival duration. These results indicate that ordinary combined chemotherapy has limited ability to improve the prognosis of aggressive ATL. Our previous study indicated that expression of P-glycoprotein in ATL cells might be involved in resistance to chemotherapeutic agents, particularly doxorubicin, vincristine, and etoposide. Therefore, new therapeutic strategies will be necessary to improve the prognosis of ATL patients.

The effects of temperature and grain size on the deformation and fracture behaviour of recrystallized Ni3Al doped with boron were investigated by tensile tests at temperatures up to 973 K as a function of grain sizes from 1.6 to 105µm. The yield stress showed a positive temperature dependence to a peak temperature in somewhat different manners depending on the grain size. For coarse-grained specimens, a rapid drop in elongation was observed with increasing temperature. The predominant fracture mode changed with temperature from the transgranular fracture of {1 1 1} cracking to brittle intergranular fracture. This embrittlement at elevated temperatures was considered to occur by a high stress concentration at grain boundaries arising from increased flow stress level and the occurrence of grain boundary sliding (GBS). In contrast, the elongation was not so markedly decreased with temperature for intermediate- and fine-grained specimens which exhibited ductile intergranular fracture and cavitation fracture, respectively, at elevated temperatures, and a slant-type fracture and cup-cone fracture, respectively, at low temperatures. The suppression of serious high-temperature embrittlement for intermediate-grained specimens was explained in terms of the slow propagation of a crack formed by GBS, owing to stress relaxation by dynamic recrystallization (DR) and plastic deformation. In the case of ultra-fine-grained specimens a large elongation was developed at elevated temperatures, which was interpreted as that the further occurrence of DR with increasing volume fraction of grain boundaries reduces the cavitation promoted by GBS, and that the limited sliding length due to extremely small grain diameter raises the stress for cavity formation.

Atomic arrangements at a nearest neighbour anti-phase boundary (APB), on the (110) plane, connected by 1/2[111] superpartials in Fe3Al were directly observed in an edge-on view using high resolution electron microscopy (HREM). In HREM images, Al atom positions projected along the [110] direction were revealed as white dots. A single step on the APB interface, which is related to a jog on the partial dislocation line, was identified directly from the geometrical patterns of the white dots. Detailed comparisons of the experimental data with simulated images indicated that the apparent relaxation of atomic rows at the APB is very localized to its interface even at the step.

Single phase Nb3Al alloys and two phase Nb3Al alloys containing a Nb solid solution (Nbss) or Nb2Al are fabricated by a modified reactive sintering process. This process, called the clad chip extrusion (CCE) method, consists of clad-rolling Al/Nb/Al three layered plates, cutting the clad-rolled plates into pieces, extruding a container filled with the pieces and heat-treating the extruded Nb/Al composite rod with a very fine micro structure. Heat-treatments combined with HIPing are used to form high-density Nb3Al compacts containing neither Kirkendall voids nor alumina particles. Nb3Al alloys are brittle below 1300 K and fracture before yielding in compression tests in this temperature region. Single phase Nb3Al alloys with the compositions from 20·2 to 23·3 at% Al possess very high yield strength in compression above 1473 K. The compressive strengths are almost independent of Al content, and the materials exhibit dynamic recrystallization around initial grain boundaries at large strains. Two phase alloys of Nb3Al and Nbss deform, without cracking at lower temperatures, to larger strains, although they have lower yield strengths.

Yielding and plastic flow behavior of B2-type Fe-39.5 mol.% Al were investigated by deforming single crystals in the temperature range from room temperature to 1073 K. Yield stress exhibits a distinct positive temperature dependence followed by a peak for all the orientations examined. The temperatures of the anomalous peak are located between 823 and 873 K for all the orientations except the near-[111] orientation. Only for the near-[111] orientation the peak temperature is located between 773 and 823 K. The slip transition from 〈111〉 direction at intermediate temperatures to 〈100〉 at high temperatures occurs at the peak temperatures. The yield stress at 773 K exhibits a strong orientation dependence and has a good correlation with respect to non-glide stress component. Specimens having compression axes of χ ⪖ 0° exhibit serrations in stress-strain curves below the peak temperatures, whereas the serrations are not observed in those of χ < 0°. In addition, a yield drop is observed around the peak temperatures for all the orientations. Below the peak temperatures, even as low as at room temperature, the yield stress hardly depends on the applied strain rate. This indicates that the motion of 〈111〉-type superdislocations has very small strain-rate sensitivity in the temperature range. On the other hand, there is a strong strain-rate dependence at the peak temperature and above, indicating that the motion of 〈100〉-type dislocations is strongly rate sensitive. The positive temperature dependence of yield stress in B2 FeAl is discussed on the basis of the present results.

Tensile properties and plastic deformation modes ofß zirconium-niobium alloys were investigated at 290 and 77 K in the wide composition range from metastable to stableß phase. Three types of plastic deformation modes, {332}<113> twinning, {112}<111> twinning and slip, were observed depending on alloy composition and temperature. {332}<113> twinning, which occurs in metastableß zirconium alloys, is related to the stability ofß phase to? decomposition and leads to low yield stress and large elongation. On the other hand, {112}<111> twinning, which appears in stableß zirconium alloys, results from high critical stress for slip due to solution hardening and high Peierls stress and does not affect tensile properties significantly. The results obtained for zirconium-alloys are similar to those forß titanium alloys, strongly suggesting that {332}<113> twinning is an important plastic deformation mode which is common toß phase alloys containing athermal? phase.

Abstract: Microstructure and crystallography of a stress-induced plate in metastableβ titanium alloys, Ti-V, Ti-Mo, Ti-Nb, Ti-Fe, were investigated by a combination of two surface trace analysis and transmission electron microscopy. Stress-inducedω phase transformation or {332} 〈113〉 twinning appeared in circumstances whereβ phase was very unstable. It was found that there were two types of {332} 〈113〉 twinning, depending on whether one variant ofω phase was preferentially induced in a twin or not. Stress-inducedω phase not relating to {332} 〈113〉 twinning was not observed in matrix. This suggests that stress-inducedω phase transformation is accompanied with {332} 〈113〉 twinning. Preferential formation of oneω variant was influenced not only by alloy system and its composition, but also by cooling rate from solution treatment temperature. The relation between athermalω structure and stress-inducedω phase transformation or plastic deformation mode is also discussed.

The effect of plastic deformation mode on tensile properties of quenched commercial β-phase titanium alloys has been investigated at approximately constant grain size and oxygen content. In addition, stability of β-phase has been estimated from ω-reflections or diffuse streaking in electron diffraction patterns in a manner similar to the previous works on binary β-phase titanium alloys. Dominant mode of plastic deformation is {332}<113> twinning in the alloys with large instability of β-phase, such as Ti-11.5Mo-6Zr-4. 5Sn and Ti-15Mo-5Zr, and is crystallographic slip in the alloys with small instability of β-phase, such as Ti-15Mo-5Zr-3Al, Ti-3Al-8V-6Cr-4Mo-4Zr, Ti-15V-3Cr-3Al-3Sn, Ti-8Mo-8V-2Fe-3Al, and Ti-13V-11C-3Al. Twinning leads to low yield strength and large elongation, while slip results in high yield strength and small elongation in agreement with binary and termary β-phase titanium alloys.