Solid-Form Transition Temperature Prediction from a Virtual Polymorph Screening: A Reality Check

2019 ◽  
Vol 19 (12) ◽  
pp. 7132-7137 ◽  
Author(s):  
Yuriy Abramov ◽  
Guangxu Sun ◽  
Yunfei Zhou ◽  
Mingjun Yang ◽  
Qiao Zeng ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Temperature Prediction ◽  
Reality Check ◽  
Solid Form ◽  
Polymorph Screening

scholarly journals Glass transition temperature prediction of polymers through the mass-per-flexible-bond principle

Polymer ◽  
2007 ◽  
Vol 48 (20) ◽  
pp. 6115-6124 ◽  
Author(s):  
J. Schut ◽  
D. Bolikal ◽  
I.J. Khan ◽  
A. Pesnell ◽  
A. Rege ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Prediction

scholarly journals Interpreting computed crystal energy landscapes for pharmaceutical molecules

2014 ◽  
Vol 70 (a1) ◽  
pp. C1615-C1615
Author(s):  
Sarah Price
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Prediction ◽  
Energy Landscape ◽  
Crystal Structure Prediction ◽  
Energy Landscapes ◽  
Pyridinecarboxylic Acid ◽  
Solid Form ◽  
Pharmaceutical Molecules ◽  
Polymorph Screening

Crystal Structure Prediction (CSP) algorithms aim to generate the thermodynamically feasible crystal structures of a molecule from the chemical diagram, ranking their relative stability by a necessarily approximate estimate of the crystal energy. Such calculations are becoming feasible for molecules of a size and flexibility of small molecule pharmaceuticals. Contrasting the crystal energy landscape, the computer generated structures that are thermodynamically plausible as polymorphs, with the results of experimental polymorph screening, shows that CSP studies are not limited to being a search for the most thermodynamically stable crystal structure but can play a valuable role in understanding polymorphism and the potential complexity of crystallisation behaviour.[1] This presentation will illustrate the use of CSP as a complement to industrial-type solid form screening activities. Examples will include olanzapine, [2] tazofelone, two closely related 5-HT2a agonists and 6-[(5-chloro-2-([(4-chloro-2-fluorophenyl)methyl]oxy)phenyl)methyl]-2-pyridinecarboxylic acid (GSK269984B).[3] This illustrates the use of the crystal energy landscape to understand disorder, help structurally characterise metastable polymorphs and suggest whether there are additional polymorphs to be targeted. Since crystal energy landscapes usually include a wider range of crystal structures than known polymorphs, it raises the scientific question as to what determines which structures can be observed as metastable polymorphs. Thus both scientific as well as technological challenges need to be overcome before we can predict polymorphs.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Reality Check for Researchers

PsycCRITIQUES ◽  
2009 ◽  
Vol 54 (10) ◽  
Author(s):  
Lowell Brubaker
Keyword(s):  
Reality Check

A SIMPLE QUALITATIVE DETERMINATION OF JOSEPHSON TUNNEL JUNCTION PARAMETERS NEAR THE TRANSITION TEMPERATURE

1978 ◽  
Vol 39 (C6) ◽  
pp. C6-1232-C6-1233 ◽  
Author(s):  
N. F. Pedersen ◽  
J. Mygind ◽  
O. H. Soerensen ◽  
B. Dueholm
Keyword(s):  
Transition Temperature ◽  
Tunnel Junction ◽  
Josephson Tunnel ◽  
Qualitative Determination
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