Results 221 to 230 of about 568,935 (268)
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The Journal of Physical Chemistry Letters, 2022
Hydrogenated borophenes─borophanes─have recently been synthesized as a new platform for studying low-dimensional borides, but most of their lattice structures remain unknown. Here, we determine the structures of borophane polymorphs on Ag(111) by performing extensive structural search using the cluster expansion method augmented with first-principles ...
Ying Xu +6 more
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Hydrogenated borophenes─borophanes─have recently been synthesized as a new platform for studying low-dimensional borides, but most of their lattice structures remain unknown. Here, we determine the structures of borophane polymorphs on Ag(111) by performing extensive structural search using the cluster expansion method augmented with first-principles ...
Ying Xu +6 more
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Polymorphs and Polymorphic Cocrystals of Temozolomide
Chemistry – An Asian Journal, 2008AbstractCrystal polymorphism in the antitumor drug temozolomide (TMZ), cocrystals of TMZ with 4,4′‐bipyridine‐N,N′‐dioxide (BPNO), and solid‐state stability were studied. Apart from a known X‐ray crystal structure of TMZ (form 1), two new crystalline modifications, forms 2 and 3, were obtained during attempted cocrystallization with carbamazepine and 3‐
N Jagadeesh, Babu +3 more
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Chemical Reviews, 2013
An unambiguous definition of conformational change and conformational polymorphism, as well as a quantitative basis for the likelihood of its appearance, is reviewed. Conformational adjustment and conformational change are different phenomena. Two polymorphs are conformational polymorphs only if their conformations are related by conformational change.
Cruz-Cabeza, A.J., Bernstein, J.
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An unambiguous definition of conformational change and conformational polymorphism, as well as a quantitative basis for the likelihood of its appearance, is reviewed. Conformational adjustment and conformational change are different phenomena. Two polymorphs are conformational polymorphs only if their conformations are related by conformational change.
Cruz-Cabeza, A.J., Bernstein, J.
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On the Polymorphism of Aspirin
Angewandte Chemie International Edition, 2007More headaches with aspirin: No new polymorph? Reduction and re-indexing of X-ray data collected on a crystal of the well-known form I of aspirin in a unit cell recently reported for the new form II results in a data set from which this so-called new form can be obtained and even refined isotropically! Form II, if it exists, needs to be identified with
Bond, Andrew +2 more
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Journal of Pharmaceutical Sciences, 1972
An evaluation of entropies and enthalpies of transition and fusion and a comparison of X-ray diffraction patterns and IR spectra of polymorphic forms of structurally related compounds were undertaken to obtain information which might prove useful in correlating the frequency of occurrence of polymorphism with certain aspects of chemical structure ...
S S, Yang, J K, Guillory
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An evaluation of entropies and enthalpies of transition and fusion and a comparison of X-ray diffraction patterns and IR spectra of polymorphic forms of structurally related compounds were undertaken to obtain information which might prove useful in correlating the frequency of occurrence of polymorphism with certain aspects of chemical structure ...
S S, Yang, J K, Guillory
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Journal of Pharmaceutical Sciences, 1989
As the solubility in water of the cytotoxic drug estramustine is less than 1 mg/L, polymorphism can have an impact on the bioavailability of orally administered drug. Therefore, the solid state characteristics of estramustine samples, crystallized from different solvents, were investigated by means of X-ray crystallography, thermal analysis, and IR ...
T, Wadsten, N O, Lindberg
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As the solubility in water of the cytotoxic drug estramustine is less than 1 mg/L, polymorphism can have an impact on the bioavailability of orally administered drug. Therefore, the solid state characteristics of estramustine samples, crystallized from different solvents, were investigated by means of X-ray crystallography, thermal analysis, and IR ...
T, Wadsten, N O, Lindberg
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Journal of Theoretical Biology, 1993
It is well known that for a single, autosomal locus with differential viabilities convergence to a stable equilibrium is assured. However if new alleles are introduced sequentially by mutation the final equilibrium may depend on the particular sequence. Thus the equilibrium to which the population moves will be randomly determined.
C, Cannings, J P, Tyrer, G T, Vickers
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It is well known that for a single, autosomal locus with differential viabilities convergence to a stable equilibrium is assured. However if new alleles are introduced sequentially by mutation the final equilibrium may depend on the particular sequence. Thus the equilibrium to which the population moves will be randomly determined.
C, Cannings, J P, Tyrer, G T, Vickers
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Acta Crystallographica Section C Crystal Structure Communications, 1996
The title compound, 7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diyl diacetate, C21H23NO5, was crystallized from a solution of its hydrochloride and sodium acetate. Unlike prior reports in which crystals were hexagonal shaped (orthorhombic) and in space group P2(1)2(1)2(1), the crystals in the present determination grew as large prisms (monoclinic ...
J R, Deschamps +2 more
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The title compound, 7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diyl diacetate, C21H23NO5, was crystallized from a solution of its hydrochloride and sodium acetate. Unlike prior reports in which crystals were hexagonal shaped (orthorhombic) and in space group P2(1)2(1)2(1), the crystals in the present determination grew as large prisms (monoclinic ...
J R, Deschamps +2 more
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Nature, 1968
Lecithin–water systems display a variety of phases. Several of these phases, observed at a high temperature in the presence of small amounts of water, belong to a class of structures recently discovered in the anhydrous divalent cation-soaps. In these structures the polar groups are clustered in rod-shaped regions, embedded in a disordered paraffin ...
V, Luzzati +2 more
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Lecithin–water systems display a variety of phases. Several of these phases, observed at a high temperature in the presence of small amounts of water, belong to a class of structures recently discovered in the anhydrous divalent cation-soaps. In these structures the polar groups are clustered in rod-shaped regions, embedded in a disordered paraffin ...
V, Luzzati +2 more
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Polymorphous hemangioendothelioma
The Annals of Thoracic Surgery, 1999Polymorphous hemangioendothelioma is a rare vascular tumor; only 5 patients have been previously described. Half of all cases described have occurred in the thoracic cavity, all being discovered on chest radiologic studies obtained for other reasons. This report presents the case of a female patient with polymorphous hemangioendothelioma and a brief ...
T F, Rehring, A, Deutchman, J S, Cross
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