scholarly journals Influence of high pressure on amino acids and their multicomponent crystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1192-C1192
Author(s):  
Boris Zakharov ◽  
Elena Boldyreva ◽  
Boris Kolesov ◽  
Evgeniy Losev ◽  
Sergey Arkhipov
Keyword(s):  
Crystal Structure ◽  
Amino Acids ◽  
High Pressure ◽  
Phase Transitions ◽  
Crystal Structures ◽  
High Pressures ◽  
Ministry Of Education ◽  
Amino Acid Salts ◽  
The Individual ◽  
Academy Of Sciences

The studies of molecular crystals at high pressures help to understand intermolecular interactions, their role in the formation of crystal structures and in crystal structure response to external actions. Multicomponent crystals are promising for high-pressure research since a large number of phenomena has been observed for them [1]. Crystals of amino acids, their salts and co-crystals are of special interest in this respect. They are promising as new materials and can serve as biomimetics since the structure forming units of these crystals are similar to those in biomolecules. The aim of this study was to follow the effect of increasing pressure on crystal structures of amino acid salts and co-crystals to compare the results with those obtained for individual amino acids. Glycine, alanine, serine and their corresponding salts with carboxylic acids were chosen as objects of the study. Single-crystal X-ray diffraction and Raman spectroscopy were used as main experimental techniques. Three different types of behavior of salts on increasing pressure as compared with individual crystals were observed. For some salts, adding the second component stabilized the crystal structure with respect to phase transitions [2]. In the second group, on the contrary, the salts underwent phase transitions at relatively low pressures, though individual components did not undergo phase transitions at least up to 8-10 GPa. The last, third group of salts showed phase transitions in a similar pressure range as the individual components, but the mechanism of the transition changed. The phase transitions were accompanied either by crystal structure disordering, or by switching-over hydrogen bonds [3]. This work was supported by a grant from RFBR (12-03-31541 mol_a), by the Ministry of Education and Science of Russia, Russian Academy of Sciences, and by a grant of President of Russia for State support of Russian leading Scientific Schools (project NSh-279.2014.3).

Crystal structure, compressibility and possible phase transitions in \boldvarepsilon-FeSi studied by first-principles pseudopotential calculations

1999 ◽  
Vol 55 (4) ◽  
pp. 484-493 ◽  
Author(s):  
Lidunka Vočadlo ◽  
Geoffrey D. Price ◽  
I. G. Wood
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Phase Transitions ◽  
First Principles ◽  
Stable Phase ◽  
Third Order ◽  
First Derivative ◽  
Pseudopotential Calculations ◽  
Cscl Type ◽  
Murnaghan Equation

An investigation of the relative stability of the FeSi structure and of some hypothetical polymorphs of FeSi has been made by first-principles pseudopotential calculations. It has been shown that the observed distortion from ideal sevenfold coordination is essential in stabilizing the FeSi structure relative to one of the CsCl type. Application of high pressure to FeSi is predicted to produce a structure having nearly perfect sevenfold coordination. However, it appears that FeSi having a CsCl-type structure will be the thermodynamically most stable phase for pressures greater than 13 GPa. Fitting of the calculated internal energy vs volume for the FeSi structure to a third-order Birch–Murnaghan equation of state led to values, at T = 0 K, for the bulk modulus, K 0, and for its first derivative with respect to pressure, K 0′, of 227 GPa and 3.9, respectively.

High-Pressure Phase Transitions of Cubic Y 2 O 3 under High Pressures by In-situ Synchrotron X-Ray Diffraction

2019 ◽  
Vol 36 (4) ◽  
pp. 046103 ◽  
Author(s):  
Sheng Jiang ◽  
Jing Liu ◽  
Xiao-Dong Li ◽  
Yan-Chun Li ◽  
Shang-Ming He ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
High Pressures ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase

79Br, 127I NQR of Diammoniumalkyl Halides and Piperazinium Halides. Crystal Structure of Piperazinium Dibromide Monohydrate and Piperazinium Monoiodide

1989 ◽  
Vol 44 (1) ◽  
pp. 41-55 ◽  
Author(s):  
Jutta Hartmann ◽  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Temperature Range

Abstract The 79Br and 127I NQR spectra were investigated for 1,2-diammoniumethane dibromide, -diiodide, 1,3-diammoniumpropane dibromide, -diiodide, piperazinium dibromide monohydrate, and piperazinium monoiodide in the temperature range 77 ≦ T/K ≦ 420. Phase transitions could be observed for the three iodides. The temperatures for the phase transitions are: 400 K and 404 K for 1,2-diammoniumethane diiodide, 366 K for 1,3-diammoniumpropane diiodide, and 196 K for piperazinium monoiodide.The crystal structures were determined for the piperazinium compounds. Piperazinium dibromide monohydrate crystallizes monoclinic, space group C2/c, with a= 1148.7 pm, 0 = 590.5 pm, c= 1501.6pm, β = 118.18°, and Z = 4. For piperazinium monoiodide the orthorhombic space group Pmn 21 was found with a = 958.1 pm, b = 776.9 pm, c = 989.3 pm, Z = 4. Hydrogen bonds N - H ... X with X = Br, I were compared with literature data.

scholarly journals Hochdrucksynthese quaternärer Chalkogenidhalogenide AB2X3Y (A = Cu, Ag; B = In; X = S, Se, Te; Y = Cl, Br, I)/High Pressure Synthesis of Quaternary Chalcogenide Halogenides AB2X3Y (A = Cu, Ag; B = In; X = S, Se, Te; Y = Cl, Br, I)

1983 ◽  
Vol 38 (2) ◽  
pp. 155-160 ◽  
Author(s):  
Klaus-Jürgen Range ◽  
Heinz-Joachim Hübner
Keyword(s):  
High Pressure ◽  
Crystal Structures ◽  
Spinel Structure ◽  
High Pressures ◽  
Reaction Pathways ◽  
High Pressure Synthesis ◽  
Quaternary Compounds ◽  
Pressure Synthesis ◽  
High Pressures And Temperatures

Abstract Quaternary compounds AB2X3Y (A = Cu, Ag; B = In; X = S, Se, Te; Y = Cl, Br, I) could be synthesized at high pressures and temperatures. The crystal structures found are defect-zincblende (AgIn2Se3I, AgIn2Te3l, CuIn2Se3Br, CuIn2Se3I, CuIn2Te3Cl, CuIn2Te3Br, CuInTe3I), spinel (AgIn2S3Cl, AgIn2S3Br, AgIn2Se3Cl, AgIn2Se3Br, AgIn2Se3l) and defect-rocksalt (AgIn2Te3Cl, AgIn2Te3Br). A second form of CuIn2Se3l is intermediate between the zincblende and spinel structure. A survey of the different reaction pathways of AB-B2X3 mixtures at high pressures and temperatures is given.

Structural characterization of a new high-pressure phase of GaAsO4

2006 ◽  
Vol 62 (6) ◽  
pp. 1019-1024 ◽  
Author(s):  
David Santamaría-Pérez ◽  
Julien Haines ◽  
Ulises Amador ◽  
Emilio Morán ◽  
Angel Vegas
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Pressures ◽  
Ambient Conditions ◽  
Hexagonal Cell ◽  
Octahedral Sites ◽  
New Phase ◽  
Pressure Phase

As in SiO2 which, at high pressures, undergoes the α-quartz → stishovite transition, GaAsO4 transforms into a dirutile structure at 9 GPa and 1173 K. In 2002, a new GaAsO4 polymorph was found by quenching the compound from 6 GPa and 1273 K to ambient conditions. The powder diagram was indexed on the basis of a hexagonal cell (a = 8.2033, c = 4.3941 Å, V = 256.08 Å3), but the structure did not correspond to any known structure of other AXO4 compounds. We report here the ab initio crystal structure determination of this hexagonal polymorph from powder data. The new phase is isostructural to β-MnSb2O6 and it can be described as a lacunary derivative of NiAs with half the octahedral sites being vacant, but it also contains fragments of the rutile-like structure.

High Pressure Carbon Behavior Induced from Carbide Hugoniots

1997 ◽  
Vol 499 ◽  
Author(s):  
T. Sekine ◽  
E. Takazawa ◽  
T. Kobayashi
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Molar Volume ◽  
Partial Molar Volume ◽  
High Pressures ◽  
Diamond Structure ◽  
Structural Variations ◽  
Diamond Phase ◽  
Type Carbide ◽  
Diamond Type

ABSTRACTInvestigations of Hugoniots the diamond-type carbides(various SiC) and NaCl-type carbides such as TiC give some insights into the high-pressure carbon behaviors. The experimental results of phase transitions of a-SiC and β-SiC, together with those of diamond-structure Si, imply that the candidate as post-diamond phase has sixfold coordination and that a possible transition pressure is about 1–2 TPa. The NaCl-type carbide Hugoniots indicate that sixfold coordinated C is very stable at high pressures. The partial molar volume of carbon in the NaCl-type carbides ranges between 1.4 to 2.6 cnvVg-atom C at 1 atm and reaches about 2.8 cm3/g-atom C at 100 GPa. Taking into account structural variations of the corresponding metals, the volume of the sixfold coordinated C is estimated to be 1.7 cm3/g-atom C, about half of that of diamond, and the post-diamond phase appears to be extremely hard.

Phase transitions of BaCO3 at high pressures

2008 ◽  
Vol 72 (2) ◽  
pp. 659-665 ◽  
Author(s):  
S. Ono ◽  
J. P. Brodholt ◽  
G. D. Price
Keyword(s):  
Phase Transition ◽  
Experimental Study ◽  
High Pressure ◽  
Phase Transitions ◽  
Bulk Modulus ◽  
First Principles ◽  
High Pressures ◽  
Ambient Conditions ◽  
The Stability ◽  
Previous Experimental Study

AbstractFirst-principles simulations and high-pressure experiments were used to study the stability of BaCO3 carbonates at high pressures. Witherite, which is orthorhombic and isotypic with CaCO3 aragonite, is stable at ambient conditions. As pressure increases, BaCO3 transforms from witherite to an orthorhombic post-aragonite structure at 8 GPa. The calculated bulk modulus of the post-aragonite structure is 60.7 GPa, which is slightly less than that from experiments. This structure shows an axial anisotropicc ompressibility and the a axis intersects with the c axis at 70 GPa, which implies that the pressure-induced phase transition reported in previous experimental study is misidentified. Although a pyroxene-like structure is stable in Mg- and Ca-carbonates at pressures >100 GPa, our simulations showed that this structure does not appear in BaCO3.

scholarly journals Effects of hydrostatic pressure on membrane processes. Sodium channels, calcium channels, and exocytosis.

1987 ◽  
Vol 90 (6) ◽  
pp. 765-778 ◽  
Author(s):  
S H Heinemann ◽  
F Conti ◽  
W Stühmer ◽  
E Neher
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Pressures ◽  
Mean Amplitude ◽  
National Academy Of Sciences ◽  
Na Currents ◽  
Experimental Resolution ◽  
Adrenal Chromaffin ◽  
Academy Of Sciences ◽  
Ca Currents

A patch-clamp study under high hydrostatic pressure was performed by transferring cells or membrane patches into a pressure vessel (Heinemann, S. H., W. Stühmer, and F. Conti, 1987, Proceedings of the National Academy of Sciences, 84:3229-3233). Whole-cell Na currents as well as Ca currents were measured at pressures up to 40 MPa (approximately 400 atm; 1 MPa = 9.87 atm) in bovine adrenal chromaffin cells. Ca currents were found to be independent of pressure within experimental resolution. The mean amplitude and the gating kinetics of Na currents were affected by less than 20% at 10 MPa. This lack of a pronounced effect is surprising since the high-pressure nervous syndrome (HPNS), a disorder at high pressures known to result from impaired nervous transmission, manifests itself at pressures as low as 5 MPa. The results show that ion channels involved in transmission cannot be implicated in HPNS. However, when exocytosis was studied at high pressure by monitoring the cell capacitance (Neher, E., and A. Marty, 1982, Proceedings of the National Academy of Sciences, 79:6712-6716), more drastic effects were seen. The degranulation evoked by dialyzing the cell with 1 microM free Ca2+ could be slowed by a factor of 2 by application of 10 MPa. The same effect was observed for the degranulation of rat peritoneal mast cells stimulated with 40 microM of the GTP analogue GTP-gamma-S. According to these results, the process of exocytosis is the most likely site at which hydrostatic pressure can act to produce nervous disorders. Furthermore, we demonstrate that pressure can be a useful tool in the investigation of other cellular responses, since we were able to separate different steps occurring during exocytosis owing to their different activation volumes.

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