Direct sale as a means for promoting the sustainable use of plant genetic resources: The case of the Tuscany Region

Similarly to other Northern countries, Italy has witnessed a growth in recent years of forms of direct sale of agri-food products. These so-called short supply chains often open new opportunities for the development and conservation of rural areas which are not merely economic in nature. The case study described here presents the results of a survey conducted in the Tuscany Region the purpose of which was to understand if and how direct sale has a part to play in promoting more diversified agricultural systems and in increasing or maintaining agrobiodiversity. The support that the institutions provide for direct sale in this context can be considered as a form of implementation of the FAO International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) that Italy has ratified and which obliges its contracting parties to promote a sustainable use of plant genetic resources

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

Extended plasticity in commercial-purity zinc sheet

Some microstructures are presented, following on from CoA Memo. No. 137. Annealed c.p. zinc deforms predictably, while the as rolled metal retains the equiaxed grain-size produced by room-temperature rolling. Some evidence of grain growth is apparent in the material strained at 0.2 in/min

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

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

Superplasticity in Zn-based alloys

This thesis is concerned with two-basic zinc-based superplastic . alloys, the virtually. single-phase Zn --0.4 wt % Al alloy and the two-phase Zn - Al eutectoid alloy. -The first investigation is concerned with superplasticityin the Zn - 0.4 % wt Al alloy, while the second investigation is devoted to the effect-of copper additions on-the behaviour of the Zn. - Al eutectoid superplastic alloy and the possible mechanisms operating during deformation. A-zinc - 0.4 Al alloy was developed, which showed a. remarkable degree of superplasticity. at room. temperature, and. elongations of greater than 500% could be obtained at the relatively fast crosshead velocity of 0.1 inch/min. The strain7rate sensitivity (m) was found to increase with strain up to 300% on elongation (. 35 -*-. 5)-parallel to the rolling . direction. and it was also found to be anisotropic in-the plane of the sheet. The strain ratio r was also strain dependent and varied in the plane of the sheet. At 900 to the rolling direction, the strain ratio. increased from . 35 to . 75 after an elongation of 350%, that is, tending to unity (isotropy). Texture determination after straining showed a marked change and agreed qualitatively with the change in strain ratio. Grain growth occurred at room temperature, but was observed to be inhibited on superplastic deformation. Surface observations after deformation revealed that grainboundary sliding was taking place; fracture behaviour, though characteristically ductile in nature, varied with strain-rate. This alloy obeyed the Hall-Petch relationship above. a certain critical grain size, below which it was inapplicable, due to the occurrence of superplasticity. Thin-foil transmission-electron microscopy showed the importance of a dislocation recovery Mechanism in the interpretation. of this deformation behaviour, and calculations based on the current theories of volume and grainboundary diffusion, grainboundary sliding and dislocation climb/recovery, showed-that a grainboundary sliding/dislocation-climb recovery model could reasonably predict the observed. strain rate sensitivity and strain-rate. Biaxial tests confirmed the anisotropic properties observed in uniaxial. tests and also in punch-stretching the effect of-friction on cup height was contrary to that observed with workhardening metals. In the second investigation, measurements of. the-flow stress (af) and. strain-rate. sensitivity (m). over a wide range of strain- . rates (6)-and temperatures between -75-to 3000C have been made on a range of superplastic alloys, based on. the Zn - Al eutectoid, but with additions of up to 1% copper. These additions do not significantly affect af or m above about-1500C. The peak in the m. -ý curve is not displaced. by these-copper additions at temperatures above 1500C. Increasing the grain-size (L) increases af for. temperatures above about 600C but decreases. of-below this temperature.. With increasing-grain-size, the peak in m-value moves towards lower L, The dependence of af vs.. La showed that the exponent a. was strain-rate dependent and varied, from 0.6 to I at 2500C. The exponent b in the relation ý vs. 1 was independent F of stress and varied from 1.8 at 2500C to 3 at L 200C. The activation energy was grain-size and stress-dependent, and for the smallest grain size (. 55 jim), a value. of about 14 k. cal/mole was obtained in the superplastic region, while a value of near 20 k-cal/mole was obtained at the low 6 region. Creep-rate - measurements-at room-temperature showed that the secondary creep- rate decreased with increasing copper. content,, by a factor-of about 120 between 0 and 1.0% copper. . Increasing the grain size from 0.55 Um to 1.75 Um decreased the creep-rate further by a-factor varying from 10-50 times and thus an overall gain in creep resistance of 1200 times can be obtained. Uniaxial tension, torsion and_camplastometer tests were. used to cover strain-rates between. 10 3. to 104'. -mirCl in order experimentally to determine the multistage. af -e curve. Hot-totsion stress-strain curves were typical of those shown in previous published work on hot working, and showed that a steady-state stress was obtained during superplasticity. . In uniaxial tension, elongations of greater than 1000% were obtained at the very high initial strain-rate of 1.6 x 101 min-1. Grain coarsening occurred during deformation and was found to be strain-rate and strain dependent. Thin-foil transmission electron microscopy showed the extensive activity. of dislocations and diffusional processes. Dislocation-free structures and rounded interphase boundaries-were observed under . superplastic. conditions. Also, though many of the grains appeared equiaxed after deformation, a variety of odd-shaped grains were observed, particularly in hot torsion, where there was evidence of accelerated spherodization. Fracture. behaviour was dependent on grain size, temperature and strain-rate sensitivity. Calculated of curves,. from current theories, suggested that a dislocation-climb-recovery/grainboundary sliding model, based on grainboundary diffusivity was the operating mechanism during superplasticity

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

Persistence of Jewish-Muslim Reconciliatory Activism in the Face of Threats and “Terrorism” (Real and Perceived) From All Sides

This dissertation concerns how Jewish-Muslim and Israel-Palestine grassroots activism can persist in the face of threats to the safety, freedom, lives, or even simply the income and employment of those engaged in acts of sustained resistance. At the heart of the study are the experiences of participants in the Hashlamah Project, an inter-religious collaboration project, involving Jews and Muslims. Across chapters and even nations, chapters of this organization faced similar threats and found universally-applicable solutions emerging for confronting those threats and persisting in the face of them. This raised the question of whether revolutionaries and activists in general can persevere with such work in the face of this sort of menacing. The study found answers to this in determining what methods were most widely employed and which had the best results. The results of the study showed an array of widely-employed methods for navigating threats in high risk activism, and persevering with such work in the face of these threats. This dissertation is available in open access at AURA: Antioch University Repository and Archive, http://aura.antioch.edu/ and OhioLINK ETD Center, https://etd.ohiolink.edu/