The actual pressure and temperature at the melt of elemental vanadium

It is claimed that all of the pressure scales of the reported melting curves derived by diamond anvil cell experiments require a correction which takes into account the pressure thermal shift, where vanadium is an illustrative example. The linear behavior of the thermal pressure (Pth) vs. the temperature, as predicted by first principles theoretical assumptions is then experimentally confirmed. This allows extrapolation to determine of the actual pressure and thermal temperature at the melt. Accounting for the role of the pressure transmitting media in diamond anvil cell experiments, the analysis of elemental vanadium melting curve is presented. It is shown that the appropriate correction of shock waves melting data which takes into account the radiation absorbed by the LiF window, applies only to vanadium metal. The correct pressure scale of vanadium metal as derived by diamond anvil cell is presented.Comment: 17 pages, 4 figure

Innovation and access to technologies for sustainable development: diagnosing weaknesses and identifying interventions in the Transnational Arena

Sustainable development – improving human well-being across present generations without compromising the ability of future generations to meet their own needs – is a central challenge for the 21st century. Technological innovation can play an important role in moving society toward sustainable development. However, poor, marginalized, and future populations often do not fully benefit from innovation due to their lack of market or political power to influence innovation processes. As a result, current innovation systems fail to contribute as much as they might to meeting sustainable development goals. This paper focuses on how actors and institutions operating in the transnational arena can mitigate such shortfalls. To identify the most important transnational functions required to meet sustainable development needs our analysis undertook three main steps. First, we developed a framework to diagnose blockages in the global innovation system for particular technologies. This framework was built on existing theory and new empirical analysis. On the theory side, we drew from the literatures of systems dynamics; technology and sectoral innovation systems, science and technology studies, the economics of innovation, and global governance. On the empirical front, we conducted eighteen detailed case studies of technology innovation in multiple sectors relevant to sustainable development: water, energy, health, food, and manufactured goods. We use the framework to analyze our case studies in the common language of (1) technology stocks, (2) non-linear flows between stocks substantiated by specific mechanisms, and (3) characteristics of actors and socio-technical conditions (STCs) which mediate the flows between stocks . We identify blockages in the innovation system for each of the cases, diagnosing where in the innovation system flows were hindered and which specific sets of STCs and actor characteristics were associated with these blockages. Figure E.1 displays the components of our framework and how they relate

Shock metamorphism of clay minerals on Mars by meteor impact

International audienceAbstract A large fraction of clay minerals detected on Mars by infrared remote sensing represent materials exhumed from the subsurface by meteor impact, begging the question of whether the infrared features used to detect the clays are affected by shock associated with the impacts. We used X‐ray diffraction and infrared and Mössbauer spectroscopy to evaluate the mineralogy of five clay minerals after experimentally shocking them to six shock pressures from ~10 to 40 GPa. The shocked clays exhibit three main relevant shock effects: (1) an overall decrease in infrared spectral contrast in the impact‐fragmented materials, (2) oxidation of Fe in ferrous clays, and (3) loss of some spectral structure in relatively well‐ordered clays such as kaolinite. Other than the widespread oxidation of ferrous clays, shock metamorphism likely has little effect on the accurate interpretation of clay mineralogy on Mars from remote sensing data. However, we are able to identify rare cases of extreme shock in some Martian clay deposits

Examining structural and related spectral change in marsrelevant phyllosilicates after experimental impacts between 10-40 GPA

© 2016, Clay Minerals Society. All rights reserved.Accurate clay mineral identification is key to understanding past aqueous activity on Mars, but martian phyllosilicates are old (>3.5 Ga) and have been heavily bombarded by meteoroid impacts. Meteoroid impacts can alter clay mineral structures and spectral signatures, making accurate remote sensing identifications challenging. This paper uses nuclear magnetic resonance (NMR) spectroscopy to examine the short-range structural deformation induced in clay mineral samples of known composition by artificial impacts and calcination. Structural changes are then related to changes in the visible-near infrared (VNIR) and mid-infrared (MIR) spectra of these clay mineral samples. The susceptibility of phyllosilicates to structural deformation after experimental impacts varies by structure. Experimental results showed that trioctahedral, Mg(II)-rich saponite was structurally resilient up to peak pressures of 39.8 GPa and its unchanged post-impact spectra reflected this. Experimental data on kaolinite showed that this Al(III)-rich, dioctahedral phyllosilicate was susceptible to structural alteration at peak pressures ≥ 25.1 GPa. This result is similar to previously reported experimental results on the Fe(III)-rich dioctahedral smectite nontronite, suggesting that dioctahedral phyllosilicates may be more susceptible to shock-induced structural deformation than trioctahedral phyllosilicates. The octahedral vacancies present in dioctahedral phyllosilicates may drive this increased susceptibility to deformation relative to trioctahedral phyllosilicates with fully occupied octahedral sheets. Thermal alteration accompanies shock in meteoroid impacts, but shock differs from thermal alteration. NMR spectroscopy showed that structural deformation in thermally altered phyllosilicates differs from that found in shocked phyllosilicates. Similar to shock, dioctahedral phyllosilicates are also more susceptible to thermal alteration. This differential susceptibility to impact-alteration may help explain generic smectite identifications from heavily bombarded terrains on Mars.Link_to_subscribed_fulltex

Structural and spectroscopic changes to natural nontronite induced by experimental impacts between 10 and 40 GPa

©2015. American Geophysical Union. All Rights Reserved.Many phyllosilicate deposits remotely detected on Mars occur within bombarded terrains. Shock metamorphism from meteor impacts alters mineral structures, producing changed mineral spectra. Thus, impacts have likely affected the spectra of remotely sensed Martian phyllosilicates. We present spectral analysis results for a natural nontronite sample before and after laboratory-generated impacts over five peak pressures between 10 and 40 GPa. We conducted a suite of spectroscopic analyses to characterize the sample's impact-induced structural and spectral changes. Nontronite becomes increasingly disordered with increasing peak impact pressure. Every infrared spectroscopic technique used showed evidence of structural changes at shock pressures above ~25 GPa. Reflectance spectroscopy in the visible near-infrared region is primarily sensitive to the vibrations of metal-OH and interlayer H2O groups in the nontronite octahedral sheet. Midinfrared (MIR) spectroscopic techniques are sensitive to the vibrations of silicon and oxygen in the nontronite tetrahedral sheet. Because the tetrahedral and octahedral sheets of nontronite deform differently, impact-driven structural deformation may contribute to differences in phyllosilicate detection between remote sensing techniques sensitive to different parts of the nontronite structure. Observed spectroscopic changes also indicated that the sample's octahedral and tetrahedral sheets were structurally deformed but not completely dehydroxylated. This finding is an important distinction from previous studies of thermally altered phyllosilicates in which dehydroxylation follows dehydration in a stepwise progression preceding structural deformation. Impact alteration may thus complicate mineral-specific identifications based on the location of OH-group bands in remotely detected spectra. This is a key implication for Martian remote sensing arising from our results.Link_to_subscribed_fulltex