Search

During the deformation of Mg alloys, {10–12} extension twin often contributes to the formation of basal texture but rarely assists the nucleation of recrystallization, i.e., effective grain refinement, therefore it seems to make against the improvement of formability and mechanical properties. In this work, {10–12} extension twin has been creatively utilized as a preference nucleation site for static recrystallization (SRX), achieving grain refinement and orientation randomization in a Mg-Gd-Y alloy using multi-directional impact forging (MDIF) and subsequent annealing treatment. Effect of {10–12} extension twin on SRX behavior has been investigated by annealing treatment at 450 °C using quasi-in-situ optical microscopy (OM) and quasi-in-situ electron back-scattering diffraction (EBSD). The microstructural evolution during annealing shows that several SRX gains can nucleate from the grain boundary of untwinned grains, but they only have few influences on the final microstructure due to their limited volume faction and sluggish growth. In contrast, a large number of SRX gains can initiate from {10–12} extension twin and grow up without the confine of twin boundaries. Finally, they consume their parent grains and make the main contribution to grain refinement. This should be attributed to those pinned {10–12} twin boundary, by interacting with various dislocation slips during the MDIF process, which can operate like grain boundary, store enough strain energy, and promote the nucleation of SRX during annealing. On the other hand, SRX grains usually keep initial random orientation and further randomize the forging texture during annealing treatment. [ABSTRACT FROM AUTHOR]

Objective:Patients with diabetic foot ulcers (DFU) have an increased risk of lower extremity amputation. A retrospective chart review of patients with DFUs attending the Foot Treatment and Assessment chiropodist-led outpatient clinic at an inner-city academic hospital was conducted to determine wound healing outcomes and characteristics contributing to outcomes.Method:We reviewed the complete clinical history of 279 patients with 332 DFUs spanning over a five-year period.Results:The mean age of patients was 61.5±12.5 years and most patients (83.5%) had one DFU. The majority of wounds (82.5%) were in the forefoot. Overall, 267/332 (80.5%) wounds healed. A greater proportion of wounds healed in the forefoot (82.5%) and midfoot (87.1%) than hindfoot (51.9%; p<0.001). Using a logistic regression model, palpable pedal pulse and use of a total contact cast were associated with better wound healing.Conclusion:Our findings are the first to demonstrate the benefits of chiropodists leading an acute care outpatient clinic in the management of DFUs in Canada and delivers wound healing outcomes equivalent to or exceeding those previously published.

Two atmospheric diffusion models, the box model ad the ATDL (Atmospheric Turbulent and Diffusion Laboratory) model, were used to calculate regional methane (CH4) emissions of rice fields in the Beijing area. Compared with conventional closed chamber measurements, the box model overestimated CH4emission because of meteorological conditions--the ground inverse layer was not favorable for the application of the model during the rice-growing season. The ATDL model, on the other hand, handled this unfavorable meteorological condition and gave reasonable CH4emission estimates (about 6.1–8.5 mg m−2h−1) close to conventional measurements (about 0.3–14.3 mg m−2h−1) in June, a period generally characterized by significant CH4emission from rice fields. In September, CH4emission as measured with closed chambers was negligible (about 0–0.3 mg m−2h−1), but the ATDL model still calculated it to be about 2.8–5.3 mg m−2h−1, albeit at a low level and considerably below the June emission level. This discrepancy cannot be explained at present and needs further stuy. Most likely causes are measurement artifacts and/or the presence of minor local CH4sources (ditches, field depressions) in the study area. The application of atmospheric diffusion models for regional CH4emission estimation depends greatly on meteorological conditions. Moreover, the models tend to give much more reliable results during periods of rather high CH4emission. This coincides with the time that such regional CH4emission estimates are most valuable. The atmospheric diffusion models complement the closed chamber method by providing integrated CH4emission estimates from 1–100-km2rice areas. Detailed information about agricultural management of rice fields and other potential CH4sources within the study region are necessary to better understand the integrated regional emission estimates.

The microstructure and tensile properties of twin and grain size strengthening Mg–6.85Gd–5.79Y–0.44Zr alloy have been investigated and characterized by optical microscopy (OM), scanning electron microscopy (SEM), and electron back-scattering diffraction (EBSD). Their room temperature tensile results exhibit that twin strengthening can enhance the strength of Mg–Gd–Y–Zr alloy but sacrifice its ductility or toughness. This should be attributed that lenticular {10−12} twins with high-stress localization directly lead to a brittle failure. In contrast, the strength, ductility, and toughness were synchronously improved for the grain size strengthening Mg–Gd–Y–Zr alloy, i.e., the ultimate tensile strength, uniform elongation, and static toughness increased to 254 (259–245) MPa, 1.02 (1.40–0.55)%, and 5.7 (6.7–4.2) MJ/m3, respectively. This ductility increment should have resulted from fine recrystallization that was free from stress concentration and accommodated the tensile strain by more non-basal slip and grain boundary sliding or grain rotation.