Phasing in crystallography: a modern perspective Giacovazzo, Carmelo
Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Scienze fisiche e naturali,
03/2013, Volume:
24, Issue:
Suppl 1
Journal Article
Peer reviewed
Phasing by crystallographic methods dramatically contributed to the development of the modern Sciences. As effect of their application, hundreds of thousands structures have been deposited in ...appropriate databases, a mine of information for chemistry, physics, geosciences and biology, so far only partially exploited. In this paper the historical development of the phasing approaches and the connected scientific paradigms are discussed. A short presentation of the state of the art is also given, together with short term perspectives.
Laue lenses for gamma-ray astronomy Frontera, Filippo
Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Scienze fisiche e naturali,
03/2013, Volume:
24, Issue:
Suppl 1
Journal Article
Peer reviewed
Laue lenses offer the possibility to efficiently focus soft gamma-rays with energy beyond 70/100 keV, thus significantly increasing the sensitivity of the current astronomical instrumentation. I ...report on the development status of these new focusing telescopes.
Time-resolved Laue diffraction is an elegant approach by which polychromatic X-ray pulses are used in combination with rapid laser triggering of light-sensitive samples so as to make a movie of ...protein reaction dynamics in real time. The current state-of-the-art with protein Laue diffraction has been time-resolved studies of light-induced conformational changes in myoglobin-CO with 150 ps resolution. Myoglobin has traversed the whole history of pump–probe Laue diffraction, yielding a massive amount of data that have provided considerable insight into the understanding of protein dynamics. A picture of factors governing myoglobin dynamics following ligand dissociation has been drawn from data arising from wild-type and mutant proteins. Other heme proteins have been studied using this approach:
Scapharca inequivalvis
dimeric hemoglobin, the FixL PAS domain and the photosynthetic reaction center complex of
Blastochloris viridis
.
Combining pharmacotherapy with psychosocial and behavioral interventions has helped improve the treatment of alcohol dependence. However, the clinical use of effective medications, such as ...naltrexone, is limited by poor adherence to a daily oral regimen. Recently, a once monthly extended-release injectable formulation of naltrexone (Vivitrol, Alkermes, Inc.) became the first FDA-approved long-acting formulation of naltrexone for alcohol dependence. Compared with the oral preparation, extended-release naltrexone shows reduced peaks and minimal fluctuations in plasma levels that may possibly lead to a more benign adverse-event profile. The administration of long-acting naltrexone in conjunction with psychosocial support has been associated with significant improvement in drinking outcome measures, especially among patients who are abstinent entering treatment. Additional studies are warranted to increase the knowledge on the clinical applications of long-acting naltrexone in other addictive disorders and to compare extended-release naltrexone with other long-acting formulations that are in development. The clinical availability of extended-release naltrexone has the potential to enhance treatment outcomes for alcohol and other drug dependence disorders.
Chemical impurity contained in the coolant helium of Very High Temperature Reactors (VHTRs) affects not only the deterioration of mechanical strength caused by decarburization of the high-temperature ...materials utilized at the heat transfer tubes of the Intermediate Heat Exchanger (IHX) but also the deterioration of heat transfer efficiency caused by carbon deposition, which could occur at the surface of the heat transfer tubes. Such deterioration results in the shortening of the lifetime of high-temperature equipment. Since the helium purification technology applied in past high-temperature gas-cooled reactors can only maintain the core integrity by limiting the oxidation of graphite, it is necessary to establish a control technology in order to maintain the mechanical strength as well as heat transfer efficiency of high-temperature equipment. In this study, carbon deposition that could occur at the surface of the heat transfer tubes of the IHX and decarburization of Hastelloy XR used at the heat transfer tubes were evaluated by referring to the actual chemistry data obtained by the HTTR. Also, the chemical composition to be maintained during a reactor operation was proposed by evaluating not only the core graphite oxidation but also carbon deposition and decarburization. It was identified that when the chemical composition could not be maintained adequately, the injection of 10 ppm carbon monoxide could effectively control the chemical composition towards the designated area at the chromium stability diagram where the stable oxidized layer would be generated sufficiently. The proposed chemistry control technology is expected to contribute to the economy of the purification systems of future VHTRs.
Information on the Earth’s interior cannot be derived from direct observations since very few rocks on the Earth’s surface come from below the crust; thus, we have to rely on detailed geochemical and ...petrological studies of meteorites, basalts and kimberlites as well as measurements of seismic wave speeds throughout the globe. Such studies have revealed an increasingly complex picture of the Earth’s mantle. One of the keys for decoding this complex information and hence for narrowing the range of acceptable compositional and thermal models of our planet is the acquisition of elasticity and phase equilibrium data at pressures and temperature conditions that are as close as possible to those present inside the Earth. Developments in the area of diamond anvil cell methodology coupled with the use of bright synchrotron sources and laser heating have made possible the acquisition of X-ray diffraction data at extreme
P
–
T
conditions and the determination of high-pressure and high-temperature structures of minerals.
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