scholarly journals Rationale for BepiColombo Studies of Mercury’s Surface and Composition

2020 ◽  
Vol 216 (4) ◽  
Author(s):  
David A. Rothery ◽  
Matteo Massironi ◽  
Giulia Alemanno ◽  
Océane Barraud ◽  
Sebastien Besse ◽  
...  
Keyword(s):  
Heliocentric Distance ◽  
Topographic Mapping ◽  
Space Weathering ◽  
Volatile Species ◽  
Origin And Evolution ◽  
Geological Processes ◽  
Physical Chemical ◽  
Crustal Origin ◽  
Northern And Southern Hemispheres

Abstract BepiColombo has a larger and in many ways more capable suite of instruments relevant for determination of the topographic, physical, chemical and mineralogical properties of Mercury’s surface than the suite carried by NASA’s MESSENGER spacecraft. Moreover, BepiColombo’s data rate is substantially higher. This equips it to confirm, elaborate upon, and go beyond many of MESSENGER’s remarkable achievements. Furthermore, the geometry of BepiColombo’s orbital science campaign, beginning in 2026, will enable it to make uniformly resolved observations of both northern and southern hemispheres. This will offer more detailed and complete imaging and topographic mapping, element mapping with better sensitivity and improved spatial resolution, and totally new mineralogical mapping. We discuss MESSENGER data in the context of preparing for BepiColombo, and describe the contributions that we expect BepiColombo to make towards increased knowledge and understanding of Mercury’s surface and its composition. Much current work, including analysis of analogue materials, is directed towards better preparing ourselves to understand what BepiColombo might reveal. Some of MESSENGER’s more remarkable observations were obtained under unique or extreme conditions. BepiColombo should be able to confirm the validity of these observations and reveal the extent to which they are representative of the planet as a whole. It will also make new observations to clarify geological processes governing and reflecting crustal origin and evolution. We anticipate that the insights gained into Mercury’s geological history and its current space weathering environment will enable us to better understand the relationships of surface chemistry, morphologies and structures with the composition of crustal types, including the nature and mobility of volatile species. This will enable estimation of the composition of the mantle from which the crust was derived, and lead to tighter constraints on models for Mercury’s origin including the nature and original heliocentric distance of the material from which it formed.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

scholarly journals Determination of trace metals in water from Mangueira Lagoon – RS, Brazil

2018 ◽  
Vol 13 (3) ◽  
pp. 612-620
Author(s):  
Filipe Sousa dos Santos ◽  
Eduarda Medran Rangel ◽  
Pedro José Sanches Filho
Keyword(s):  
Trace Metals ◽  
Atomic Emission ◽  
Atomic Absorption Spectrophotometry ◽  
Emission Spectrometry ◽  
Chemical Parameters ◽  
Chelex 100 ◽  
Physical Chemical ◽  
Low Degree ◽  
Copper Zinc

Abstract Determination of trace metals was carried out in Mangueira Lagoon, in the southern zone of Rio Grande do Sul. Samples were collected at five points to evaluate the concentrations of the following trace metals: copper, zinc, lead, chromium, nickel and iron. Metals were determined by digestion with concentrated nitric acid and pre-concentrated in Chelex 100 resin analyzed by atomic absorption spectrophotometry. In parallel, the physical-chemical parameters pH, chlorides, alkalinity, hardness and organic matter in the water were determined. Potassium and sodium metals were analyzed by atomic emission spectrometry. The analyzes of pH and conductance were analyzed in the field while the others were done in the laboratory of the research group of environmental contaminants (GPCA). Through the results of physical-chemical parameters of the water, the Mangueira Lagoon exhibits a low degree of contamination, but in the future may compromise the biota of the lagoon. Regarding the focus of this work, of Cu, Cr, Fe, Ni, Pb, and Zn (heavy metals), only lead and iron obtained the values above that are established in CONAMA 357/2005.

scholarly journals The multivariate calculation of material balances of flowsheets for separating ternary mixtures of different physical-chemical nature

2016 ◽  
Vol 11 (3) ◽  
pp. 47-57 ◽  
Author(s):  
A. V. Frolkova ◽  
M. A. Ablizin ◽  
M. A. Mayevskiy ◽  
A. K. Frolkova
Keyword(s):  
Phase Diagrams ◽  
Chemical Nature ◽  
Material Balance ◽  
Ternary Systems ◽  
Butyl Alcohol ◽  
Ternary Mixtures ◽  
Two Phase ◽  
Physical Chemical ◽  
Alcohol Water

An approach to the determination of free variables required for calculating the material balance of the flowsheet of ternary mixtures separation is presented. Phase diagrams of the considered ternary systems are characterized by the presence of a two-phase splitting area and by the presence of different amounts of azeotropes (classes 3.1.0, 3.1.1, 3.2.1 and 3.3.1). For all the systems flowsheets containing three rectification columns and a florentine vessel for separation were suggested. The multivariance of the solution of the balance problem was shown. The approach was illustrated by the example of real ternary systems characterized by different phase diagrams (methanol - chloroform - water, butyl alcohol - water - toluene, nitromethane - hexane - water). The parameters of the rectification columns were presented.

scholarly journals PHYSICAL-CHEMICAL FORMATION CONDITIONS OF URANIUM-TITANIUM-METAGEL MINERALIZATION AT THE GOLD-URANIUM ELKON DEPOSIT

2017 ◽  
pp. 52-57 ◽  
Author(s):  
M. M. Komarova ◽  
VL. B. Komarov ◽  
A. P. Aleshin ◽  
T. L. Krylova
Keyword(s):  
Crystalline Form ◽  
Fluid Regime ◽  
Ore Formation ◽  
Physical Chemical ◽  
Wide Range ◽  
Moderate Salinity ◽  
Formation Conditions ◽  
Carbonate Composition ◽  
Main Factor

A wide range of the temperatures of hydrothermal fluid regime (430-103 °C) has been revealed in the result of microthermometric study of the fluid inclusions in the minerals of pre-ore and post-ore stages developed at the Elkon deposit. Average temperatures, as well as the temperature variation are similar for both pre-ore and post-ore stages. It allows sure determination of temperatures of uranium ore formation as 400-120 °C. Fluids possessed Na-chloride, rarely Na-chloride-carbonate composition and moderate salinity (6-16 wt. % · NaCl equiv.). The wide range of tem-peratures confirms an assumption made before that various temperatures were the reason of formation of uranium mineralization both in the form of predominantly amorphous phase (U-Ti-metagel), as well as the rarely crystalline form (brannerite). Abrupt temperature decrease was apparently the main factor of the ore precipitation.

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