Search results for "polymorphs"

THE ASSOCIATION BETWEEN PROGRESSION OF POST-SURGICAL CALF VEIN THROMBOSIS AND 4G/5G POLYMORPHSM IN THE PROMOTER OF THE PLASMINOGEN ACTIVATOR INHIBITOR

2006

The formation of silica high temperature polymorphs from quartz: Influence of grain size and mineralising agents

2015

Abstract The formation of high-temperature silica polymorphs in presence of Na and K has been studied at various temperatures and soaking times, starting from quartzes of different grain size, ex situ as well as in situ. The results show that cristobalite and tridymite formation is strongly influenced by the nature and the amount of mineraliser added. In particular, K seems to discriminate more between the two structures, as it produces the largest observed amount of cristobalite. The disappearance of quartz can be controlled by the proper combination of mineraliser/temperature/time, which in turn control the amount and the type of polymorph formed, together with the amount of amorphous mat…

Study of the different polymorphs of alumina and transitional phases appearing in the first oxidation stage of aluminium : simulation at the atomic s…

2014

The goal of this work is to develop a new SMTB-Q potential in order to study the early stages of the oxidation of aluminium by molecular dynamics (MD).Our potential is able to model different alumina polymorphs as well as transitions from the amorphous state to a crystalline phase. Our approach couples a covalent term with the charge. It uses Rapp_ and Goddard scheme for the electrostatic part and the model of alternating network developed by C. Noguera for the covalent part.The SMTB-Q potential was validated with a Monte Carlo approach. This study shows that the potential SMTB-Q gives satisfactory results for the Al-O bonding in different atomic configurations. The bonding results from the…

CaSO4 and its pressure-induced phase transitions. A density functional theory study

2012

Theoretical investigations concerning possible calcium sulfate, CaSO(4), high-pressure polymorphs have been carried out. Total-energy calculations and geometry optimizations have been performed by using density functional theory at the B3LYP level for all crystal structures considered. The following sequence of pressure-driven structural transitions has been found: anhydrite, Cmcm (in parentheses the transition pressure) → monazite-type, P2(1)/n (5 GPa) → barite-type, Pnma (8 GPa), and scheelite-type, I4(1)/a (8 GPa). The equation of state of the different polymorphs is determined, while their corresponding vibrational properties have been calculated and compared with previous theoretical r…

Extraction–Pyrolytic Method for TiO2 Polymorphs Production

2021

The authors thank V. Kuzovkov, A. Lushchik and M. Lushchik for many useful discussions. The research was (partly) performed in the Institute of Solid State Physics, University of Latvia ISSP UL. ISSP UL as the Center of Excellence is supported through the Framework Program for European universities Union Horizon 2020, H2020-WIDESPREAD-01–2016–2017-TeamingPhase2 under Grant Agreement No. 739508, CAMART2 project.

Synthesis, structural and luminescent properties of Mn-doped calcium pyrophosphate (Ca2P2O7) polymorphs

2022

The study was partially funded by the Swedish Research Council FORMAS project “Utilization of solid inorganic waste from the aquaculture industry as wood reinforcement material for flame retardancy” (grant no. 2018-01198). Vilnius University is highly acknowledged for financial support from the Science Promotion Foundation (MSF-JM-5/2021). This project has also received funding from European Social Fund (project No 09.3.3-LMT-K-712-19-0069) under grant agreement with the Research Council of Lithuania (LMTLT). The authors acknowledge the Center of Spectroscopic Characterization of Materials and Electronic/Molecular Processes ("SPECTROVERSUM" www.spectroversum.ff.vu.lt ) at the Lithuanian Nat…

Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of…

2021

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed…