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The post-dynamic recrystallization behavior of ultrafine-grained (UFG: 0.44 μm) cp-Ti under annealing, room temperature (RT) monotonic and cyclic loading was investigated across a range of temperatures and deformation rates wherever appropriate. By characterizing the grain and boundary structures, it was confirmed that recrystallization and grain growth occurred due to annealing (≥ 600 °C) and R = − 1 fatigue at RT. There was a noticeable 30 deg aggregation in misorientation distribution, along with the increased grain size. However, the hypothetical correlation between 30 deg aggregation and Σ13a or the other characteristic coincidence site lattice boundaries was found to be weak. The fatigue-induced grain growth is particularly intriguing for two reasons. First, the large monotonic deformation with low strain rate cannot trigger grain growth. Second, fatigue sharpened the basal intensity around the ND and caused a weaker texture component close to TD (load axis along the LD, perpendicular to the TD–ND plane). By contrast, high-temperature annealing only strengthened the UFG processing induced basal pole but without affecting its location. Novel insights into this fatigue-induced texture evolution in UFG cp-Ti has been provided. The lattice rotation during fatigue can be attributed to the combined effect of activation of prismatic ⟨a⟩ slip parallel to LD, and basal ⟨a⟩ slip perpendicular to it. The theoretically calculated stress to activate dislocation slip by assuming a non-equilibrium grain boundary state lent support to the above assertion. Moreover, the TEM observation evidently showed the characteristics of dislocation cross-slip and multiple slip in the grain interior.

Summary The treatment of 300-mg/day isoflavones (aglycone equivalents) (172.5 mg genistein + 127.5 mg daidzein) for 2 years failed to prevent lumbar spine and total proximal femur bone mineral density (BMD) from declining as compared with the placebo group in a randomized, double-blind, two-arm designed study enrolling 431 postmenopausal women 45–65 years old. Introduction This study evaluated the effects of soy isoflavones on bone metabolism in postmenopausal women. Methods Four hundred and thirty-one women, aged 45–65 years, orally consumed 300-mg/day isoflavones (aglycone equivalents) or a placebo for 2 years in a parallel group, randomized, double-blind, two-arm study. Each participant also ingested 600 mg of calcium and 125 IU of vitamin D 3 per day. The BMD of the lumbar spine and total proximal femur were measured using dual-energy X-ray absorptiometry at baseline and every half-year thereafter. Serum bone-specific alkaline phosphatase, urinary N-telopeptide of type 1 collagen/creatinine, and other safety assessments were examined regularly. Results Two hundred out of 217 subjects in the isoflavone group and 199 out of 214 cases in placebo group completed the treatment. Serum concentrations of isoflavone metabolites, genistein and daidzein, of the intervention group were remarkably elevated following intake of isoflavones ( p  < 0.001). However, differences in the mean percentage changes of BMD throughout the treatment period were not statistically significant (lumbar spine, p  = 0.42; total femur, p  = 0.39) between the isoflavone and placebo groups, according to the generalized estimating equation (GEE) method. A significant time trend of bone loss was observed at both sites as assessed by the GEE method following repeated measurement of BMD ( p  < 0.001). Differences in bone marker levels were not significant between the two treatment groups. Conclusion Treatment with 300-mg/day isoflavones (aglycone equivalents) failed to prevent a decline in BMD in the lumbar spine or total femur compared with the placebo group.

An autofrettage analysis of an internally pressurized thick-walled spherical shell is performed by using two closed-form solutions for an elastic linear-hardening shell and an elastic power-law hardening shell based on a strain gradient plasticity theory, which contains a microstructure-dependent length-scale parameter and can capture size effects observed at the micron scale. The analysis leads to the analytical determination of the elastic and plastic limiting pressures, the residual stress field, and the stress field induced by an operating pressure for each strain-hardening spherical shell. This is followed by a shakedown analysis of the autofrettaged thick-walled spherical shells, which results in analytical formulas for reverse yielding and elastic reloading shakedown limits. The newly obtained formulas include their classical plasticity-based counterparts as special cases. To quantitatively illustrate the new formulas derived, a parametric study is conducted. The numerical results reveal that the shakedown limit (as the upper bound of the autofrettage pressure) increases with the increase of the strain-hardening level. In addition, it is observed that the shakedown limit based on the strain gradient plasticity solution increases with the decrease of the inner radius when the shell inner radius is sufficiently small, but it approaches that (a constant value independent of the inner radius) based on the classical plasticity solution when the inner radius becomes large. This predicted size (strengthening) effect at the micron scale by the newly obtained formulas agrees with the general trends observed experimentally.

The finite element method based on GTN ductile damage mechanics model has been used to investigate the interaction effects of geometry and material constraints on fracture resistance behavior of bi-material interfaces. The geometry constraint is changed by changing the specimen width W , and the material constraint is changed by changing the work hardening mismatch. The main findings of this work are that the material constraint effect on fracture resistance of bi-material interfaces is related to geometry constraint, and there exists interaction between them. For lower geometry constraint, the material constraint effect on fracture resistance is insignificant. Under the condition of middle geometry constraint, the material constraint effect on fracture resistance is the most significant. With further increasing geometry constraint, the fracture resistance behavior of the interfaces is gradually dominated by the higher geometry constraint, and the material constraint effect becomes weaken. These results are analyzed by the stress triaxiality levels ahead of crack tips and crack path deviation.

The aim of this article was to address the effect of WC content on the microstructure, microhardness, and sliding wear resistance of laser cladded WC/Ni composite coatings. The content of WC particle in the feed powder varied in the range of 0-80 wt.%. Experimental results showed that the laser cladded coatings exhibited homogeneous microstructure without pores or cracks. By comparing with the 45# steel substrate, the microhardness of WC/Ni composite coatings was relatively high. The microhardness of coating increased with increasing the content of WC particles. The wear resistance of WC/Ni composite coatings was strongly dependent on the content of WC particle and their microstructure. When the WC content was lower than 40 wt.% in the feed powder, the wear rate of the coatings decreased with increasing WC content. The two-body abrasive wear was identified as the main wear mechanisms. For the coatings with WC content higher than 40 wt.% in the feed powder, their wear rate increased with increasing WC content. The three-body abrasive wear and fatigue wear were the main failures. The coating with 40 wt.% WC in the feed powder exhibited the best wear resistance.

In this work, the equivalent plastic strain ε p distributions ahead of crack tips for the experimental specimens with combined in-plane and out-of-plane constraints under brittle fracture condition in the literature were calculated by three-dimensional finite element. The constraint parameter A p based on the areas surrounded by ε p isolines ahead of crack tips has been comparatively analyzed with several constraint parameters ( T -stress, A 2 , Q and stress triaxiality h ) based on the crack-tip stress fields, and the capability of parameter A p for characterizing in-plane and out-of-plane crack-tip constraint effects for brittle fracture has been identified. The results show that the parameter A p has a good correlation with brittle fracture toughness K J c and J c of various specimens with different constraint levels, and it is a unified measure parameter of in-plane and out-of-plane constraint for brittle fracture. The unified correlation lines and formulae of the normalized brittle fracture toughness K J c / K r e f and J I c / J r e f with A p have been obtained for the steel, and they may be used to determine constraint-dependent or structurally relevant fracture toughness of specimens or cracked components with any constraint levels. The application methodology of the constraint parameter A p for structural integrity assessments needs to be further investigated by numerical calculations and experiments.

In this work, the stress dependent creep ductility and strain rate model have been implemented in a ductility exhaustion based damage model and the creep crack growth (CCG) rates of a Cr-Mo-V steel in compact tension (C(T)) and middle tension (M(T)) specimens with different thicknesses and crack depths have been simulated over a wide range of C*. The effects of in-plane and out-of-plane constraints on CCG rates are examined. The results show that the in-plane and out-of-plane constraint effects on CCG rate are more pronounced for the high constraint specimen geometry (C(T)), while such effects are less significant for low constraint specimen geometry (M(T)). The constraint effects on CCG rates mainly occur in low and transition C* regions and the CCG rate increases with increasing in-plane and out-of-plane constraints. There exists interaction between in-plane and out-of-plane constraint in terms of their effects on CCG rate. The higher in-plane constraint strengthens the out-of-plane constraint effect on CCG rate and higher out-of-plane constraint also strengthens the in-plane constraint effect on CCG rate. The constraint effects on creep crack growth behaviour for a wide range of C* mainly arise from the interaction of crack-tip stress states and stress dependent creep ductility of the steel in different C* levels.

In this work, the effect of stress dependent creep ductility on the creep crack growth (CCG) behaviour of steels has been investigated by finite element simulations based on ductility exhaustion damage model. The relationship between the transition region of creep ductility and the transition behaviour of CCG rate on da/dt-C* curves has been examined and the CCG life assessments of components and CCG resistance of materials for a wide range of C* were discussed. The results show that with increasing the transition region size of creep ductility, the transition C* region size on da/dt-C* curves increases. With moving transition region position of creep ductility to high stress region (increasing transition stress levels), the transition C* region on the da/dt-C* curves also moves to high C* region. Decreasing transition stress levels and transition region sizes of creep ductility and increasing the lower shelf and upper shelf creep ductility values can improve the CCG resistance of materials. If the extrapolation CCG rate data from the high C* region or from the transition C* region are used in life assessments of the components at low C* region, the non-conservative or excessive conservative results may be produced. Therefore, the CCG rate data should be obtained for a wide range of C* by long term laboratory tests or numerical predictions using the stress dependent creep ductility and model.

This study compared the clinical efficacy, safety, and tolerability of daily subcutaneous injections of teriparatide and salmon calcitonin in the treatment of postmenopausal women with established osteoporosis in Taiwan. This 6-month, multicenter, randomized, controlled study enrolled 63 women with established osteoporosis. They were randomized to receive either teriparatide 20 microg or calcitonin 100 IU daily in an open-label fashion. Lumber spine, femoral neck, total hip bone mineral density (BMD), and biochemical markers of bone turnover were measured, and adverse events and tolerability were recorded. The results at 6 months showed that patients using teriparatide had larger mean increases in spinal BMD than those who used calcitonin (4.5% vs. 0.1%), but the BMD changes in these two groups at the femoral neck and the total hip were not significant. There were also larger mean increases in bone markers in the teriparatide group than in the calcitonin group (bone specific alkaline phosphatase 142% vs. 37%; osteocalcin 154% vs. 23%). We conclude that teriparatide has more positive effects on bone formation than salmon calcitonin, as shown by the larger increments of lumbar spine BMD and bone formation markers, and caused only mild adverse events and no significant change in liver, kidney or hematological parameters. Compared with the published global results, teriparatide seems to be equally effective and safe to use in this Asian population.

The aim of this study was to assess the efficacy and safety of strontium ranelate in the treatment of postmenopausal women with osteoporosis in Taiwan. In this 12-month multicenter, randomized, double-blind, placebo-controlled study, 125 women with osteoporosis were randomly given either strontium ranelate 2 g daily or placebo. Lumbar spine, femoral neck, and total-hip bone mineral density (BMD) and biochemical markers of bone turnover were measured; adverse events and tolerability were recorded and assessed. Subjects treated with strontium ranelate showed significant increases in BMD of 5.9% at the lumbar spine, 2.6% at the femoral neck, and 2.7% at the total hip, while the placebo group exhibited no significant change at 12 months. Serum level of a formation marker (bone-specific alkaline phosphatase) was also significantly increased at 6 and 12 months. Thus, although the sample size and the treatment duration of this study could not show its effect of reducing osteoprotic fractures, strontium ranelate showed bone protection effects by increasing BMD and concentrations of a bone formation marker. Safety assessment revealed adverse events were mild and not significantly different from placebo.