The effect of grain size on workhardening and superplasticity in Zn/0.4% Al Alloy

Superplasticity*requires, amongst other things, a metal with a grain-size in the range 0.5-5μ. Theories of SP invoking dynamic recovery require that the cell-Size of the substructure for the alloy in question is larger than the SP grain-size, so that gliding dislocations are always annihilated in the grain boundaries and workhardening cannot occur (1,2). .Thus the grain-size is critical, and for a given set of conditions, there must be a grain-size greater than which SP cannot be achieved

The effect of plastic anisotropy on flange wrinkling behaviour during sheet metal forming

During the drawing of sheet metal between a die and a blankholder, compressive hoop-stresses are developed which attempt to thicken or wrinkle the flange. Previous work on this behaviour has ignored any effects due to normal or planar plastic anisotropy. In this paper it is shown that the blankholder pressure necessary to suppress wrinkling increases with decreasing normal anisotropy (r) and increases with increasing planar anisotropy (AO. The approximate plane strain conditions (daz = 0) operating in the flange can be simulated by an edge-notched tensile specimen and this simulation demonstrates the effect of texture hardening and softening upon flange wrinkling behaviour. The results obtained can be interpreted valitatively by the use of anisotropic plasticity theory. The speed of drawing also effects wrinkling, in general, the number of wrinkles decreases with increasing drawing speed

Extended plasticity in commercial-purity zinc

90% rolling-reduction of annealed commercial-purity zinc sheet (grain size 100 - 150 μ) results in the fragmentation of the large grains into, finally, stable micro-grains, 1 - 211 in diameter. The stability of the micro-grains is due to the presence of soluble and insoluble impurities which prevent recrystallization. This micro-grain material is strain-rate sensitive, and elongations of 200% have been obtained at room temperature. Although this as-rolled, 90% reduction zinc sheet is not super-plastic according to the current definition, its behaviour has led to the coining of the phase 'extended plasticity'. Evidence of grain-boundary sliding is found on examination of the surface by scanning electron microscopy, while the examination of thin foils and activation energy measurements support the dynamic softening (recovery) theory; thus, both these mechanisms must be operating, to a greater or less extent, to confer on this material the observe mechanical behaviour. It is finally concluded that it is dangerous to draw conclusions regarding the mechanism of plastic deformation from surface observations alone

Anisotropic superplasticity

Anisotropy has already been mentioned in connexion with SP. Johnson et al (1) have shown that specimens of circular cross-section, machined from hot-rolled SP Zn/Al eutectic and eutectoid plate, become elliptical on straining in the rolling direction, while the fine-grain Zn/Al eutectoid produced by the quench-4 spinoidal decomposition method did not

Antiretroviral drug resistance mutations in naïve and experienced patients in Shiraz, Iran, 2014

Resistance to antiretroviral agents is a significant concern in the clinical management of HIV-infected individuals, particularly in areas of the world where treatment options are limited. In this study, we aimed to identify HIV drug-resistance-associated mutations in 40 drug-naïve patients and 62 patients under antiretroviral therapy (ART) referred to the Shiraz HIV/AIDS Research Center – the first such data available for the south of Iran. HIV reverse transcriptase and protease genes were amplified and sequenced to determine subtypes and antiretroviral- resistance-associated mutations (RAMs). Subtype CRF35-AD recombinant was the most prevalent in all patients (98 of 102, 96 % ), followed by subtype A1, and subtype B (one each, 2 % ). Among the 40 ART-naïve patients, two mutations associated with nucleoside reverse transcriptase inhibitor (NRTI) resistance (two with Y115F and T215I) and three associated with non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance (two with G190S and Y181C, four with V179T) were found. Among ART-experienced patients, four mutations associated with resistance to NRTI, four with NNRTI, and five with protease inhibitors (PI) were found. Twenty patients with high levels of resistance were already on second-line therapy. We document for the first time in this region of Iran high levels of ART resistance to multiple drugs. Our findings call for more vigilant systematic ART resistance surveillance, increased resistance testing, careful management of patients with existing regimens, and strong advocacy for expansion of available drugs in Iran. © 2016, Springer-Verlag Wien

Is Vietnam in need of supportive policies for promoting roots and tubers development? Insights from Quang Binh province

Despite their relative importance to the Vietnamese agri-food system, root and tuber crops are under-represented in terms of supportive policies at national level. The case of Quang Binh province shows the existence of potentially more conducive frameworks at provincial level, recognizing cassava as one the three provincial strategic crops and highlighting the roles of root and tuber crops in general in replacing other crops vulnerable to climate change

Technical Report: Market opportunities and value chain analysis of fresh cassava roots in Uganda.

European UnionInternational Fund for Agricultural Developmen

Effectiveness of cassava stem pruning for inducing delay in postharvest physiological deterioration (PPD) of fresh roots

European UnionInternational Fund for Agricultural Developmen

The contribution of open extremity fractures to infection in multiply injured patients

We sought to determine whether a contaminated open fracture was a reliable component for calculating the Outcome Predictive Score in patients with multiple injuries. We studied 41 patients whose primary source of contamination was open extremity fractures. Only one of the 41 patients developed osteomyelitis. The rate of infection from an open fracture is minimal in the multiply injured patient. Inclusion of patients with open fractures in studies that assess the likelihood of infection and the value of anti-infective agents incorrectly identified patients for clinical trials and results in an overestimation of survival based on the Outcome Predictive Score. These findings suggest that open fractures should be excluded as an entry criterion in future clinical trials.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31658/1/0000592.pd