Thermal, spectroscopic, and ab initio structural characterization of carprofen polymorphs.

PubMed

Bruni, Giovanna; Gozzo, Fabia; Capsoni, Doretta; Bini, Marcella; Macchi, Piero; Simoncic, Petra; Berbenni, Vittorio; Milanese, Chiara; Girella, Alessandro; Ferrari, Stefania; Marini, Amedeo

2011-06-01

Commercial and recrystallized polycrystalline samples of carprofen, a nonsteroidal anti-inflammatory drug, were studied by thermal, spectroscopic, and structural techniques. Our investigations demonstrated that recrystallized sample, stable at room temperature (RT), is a single polymorphic form of carprofen (polymorph I) that undergoes an isostructural polymorphic transformation by heating (polymorph II). Polymorph II remains then metastable at ambient conditions. Commercial sample is instead a mixture of polymorphs I and II. The thermodynamic relationships between the two polymorphs were determined through the construction of an energy/temperature diagram. The ab initio structural determination performed on synchrotron X-Ray powder diffraction patterns recorded at RT on both polymorphs allowed us to elucidate, for the first time, their crystal structure. Both crystallize in the monoclinic space group type P2(1) /c, and the unit cell similarity index and the volumetric isostructurality index indicate that the temperature-induced polymorphic transformation I → II is isostructural. Polymorphs I and II are conformational polymorphs, sharing a very similar hydrogen bond network, but with different conformation of the propanoic skeleton, which produces two different packing. The small conformational change agrees with the low value of transition enthalpy obtained by differential scanning calorimetry measurements and the small internal energy computed with density functional methods. Copyright © 2011 Wiley-Liss, Inc.

New thermoresistant polymorph from CO2 recrystallization of minocycline hydrochloride.

PubMed

Rodrigues, Miguel A; Tiago, João M; Padrela, Luis; Matos, Henrique A; Nunes, Teresa G; Pinheiro, Lídia; Almeida, António J; de Azevedo, Edmundo Gomes

2014-11-01

To prepare and thoroughly characterize a new polymorph of the broad-spectrum antibiotic minocycline from its hydrochloride dehydrate salts. The new minocycline hydrochloride polymorph was prepared by means of the antisolvent effect caused by carbon dioxide. Minocycline recrystallized as a red crystalline hydrochloride salt, starting from solutions or suspensions containing CO2 and ethanol under defined conditions of temperature, pressure and composition. This novel polymorph (β-minocycline) revealed characteristic PXRD and FTIR patterns and a high melting point (of 247 ºC) compared to the initial minocycline hydrochloride hydrates (α-minocycline). Upon dissolution the new polymorph showed full anti-microbial activity. Solid-state NMR and DSC studies evidenced the higher chemical stability and crystalline homogeneity of β-minocycline compared to the commercial chlorohydrate powders. Molecular structures of both minocyclines present relevant differences as shown by multinuclear solid-state NMR. This work describes a new crystalline structure of minocycline and evidences the ability of ethanol-CO2 system in removing water molecules from the crystalline structure of this API, at modest pressure, temperature and relatively short time (2 h), while controlling the crystal habit. This process has therefore the potential to become a consistent alternative towards the control of the solid form of APIs.

Characterization of nicergoline polymorphs crystallized in several organic solvents.

PubMed

Malaj, Ledjan; Censi, Roberta; Capsoni, Doretta; Pellegrino, Luca; Bini, Marcella; Ferrari, Stefania; Gobetto, Roberto; Massarotti, Vincenzo; Di Martino, Piera

2011-07-01

Nicergoline (NIC), a poorly water-soluble semisynthetic ergot derivative, was crystallized from several organic solvents, obtaining two different polymorphic forms, the triclinic form I and the orthorhombic form II. NIC samples were then characterized by several techniques such as (13)C cross-polarization magic angle spinning solid-state spectroscopy, room-temperature and high-temperature X-ray powder diffraction, differential scanning calorimetry, and by analysis of weight loss, solvent content, powder density, morphology, and particle size. Solubility and intrinsic dissolution rates determined for the two polymorphic forms in water and hydrochloride solutions (HCl 0.1 N) were always higher for form II than for form I, which is actually the form used for the industrial preparation of NIC medicinal products. Preformulation studies might encourage industry for the evaluation of polymorph II, as it is more suitable for pharmaceutical applications. Results in drug delivery, as well as those obtained by the above-mentioned techniques, and the application of Burger-Ramberger's rules make it possible to conclude that there is a thermodynamic relation of monotropy between the two polymorphs. This last assumption may help formulators in predicting the relative stability of the two forms. Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association

Investigation of the L-Glutamic acid polymorphism: Comparison between stirred and stagnant conditions

NASA Astrophysics Data System (ADS)

Tahri, Yousra; Gagnière, Emilie; Chabanon, Elodie; Bounahmidi, Tijani; Mangin, Denis

2016-02-01

This work highlights the effect of the stirring, the temperature and the supersaturation on the cooling crystallization of L-Glutamic acid (LGlu) polymorphs. First, solubility measurements of the metastable polymorph α and the stable polymorph β were performed. Then, crystallization experiments were carried out in stirred vessel and in stagnant cell. All these experiments were monitored by in situ devices. The effect of the temperature on the LGlu polymorphs was found to be more relevant than the supersaturation in the stirred crystallizer. In the stagnant cell, only the stable form β crystallized regardless of the operating conditions. Moreover, an unexpected and new habit of the β form was discovered and confirmed. These results suggest that the temperature and the stirring can strongly affect the nucleation and the growth kinetics of polymorphic forms.

Temperature Dependent Characterization of Terahertz Vibrations of Explosives and Related Threat Materials

DTIC Science & Technology

2010-12-10

absorption spectra of 1,3,5,7- tetranitro-1,3,5,7-tetrazocane ( HMX ) polymorphs ,” Chem. Phys. Lett. 489(1-3), 48–53 (2010). 23. P. Main, R. E...The β polymorph is the most stable form of the four polymorphs (α,β,γ,δ) of HMX and the room temperature THz spectrum of β- HMX has been measured by...EXPRESS 27248 polymorph to be formed. The α- HMX and δ- HMX forms are described as stable above room temperature: α- HMX is stable from 377 K to 429 K [24

High pressure-temperature polymorphism of 1,1-diamino-2,2-dinitroethylene

NASA Astrophysics Data System (ADS)

Bishop, M. M.; Chellappa, R. S.; Liu, Z.; Preston, D. N.; Sandstrom, M. M.; Dattelbaum, D. M.; Vohra, Y. K.; Velisavljevic, N.

2014-05-01

1,1-diamino-2,2-dinitroethylene (FOX-7) is a low sensitivity energetic material with performance comparable to commonly used secondary explosives such as RDX and HMX. At ambient pressure, FOX-7 exhibits complex polymorphism with at least three structurally distinct phases (α, β, and γ). In this study, we have investigated the high pressure-temperature stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra and corresponding differential scanning calorimetry (DSC) measurements confirmed the known α → β (~110 °C) and α → β (~160 °C) structural phase transitions; as well as, indicated an additional transition γ → (~210 °C), with the δ phase being stable up to ~251 °C prior to decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa, revealed a potential α → β transition that could occur as early as 180 °C, while β → β+δ phase transition shifted to ~300 °C with suppression of γ phase. Decomposition was observed slightly above 325 °C at 0.9 GPa.

In situ 3D-X-ray diffraction tracking of individual grains of olivine during high-pressure/ high-temperature phase transitions

NASA Astrophysics Data System (ADS)

Rosa, A. D.; Merkel, S.; Ghosh, S.; Hilairet, N.; Perrillat, J.; Mezouar, N.; Vaughan, G.

2013-12-01

The series of phase transitions between olivine, wadsleyite and ringwoodite play an essential role for large scale dynamical processes in the Earth mantle. Detailed knowledge of the microscopic mechanism at the origin of these high-pressure and high-temperature phase transformations is useful to connect global seismic observations and geodynamics. Indeed, the textures of these phases can be induced either during mantle flow or during the phase transformations and they greatly affect the characteristics of seismic wave propagation. Here, we present a new design of diamond anvil cell experiments to collect three-dimensional diffraction images and track individual grains inside a polycristalline sample at high pressure and high temperature. The instrumentation includes a new resistively heated diamond anvil cell developed at beamline ID27 of the ESRF which provided stable and homogenous temperature condition over more than 24 hours. In our experiments, the pressure is first increased up to 12 GPa at a constant temperature of T = 800 K. The temperature is then further increased to 1300 K to reach the stability field of the high-pressure polymorph. Upon further compression the transformation of olivine to its high-pressure polymorph is successfully monitored. At each pressure-temperature step and while the sample is transforming the crystallographic parameters, the orientations and positions of grains within the sample are tracked in situ using three-dimensional X-ray diffraction. This will provide important information on the micromechanical properties of olivine including orientation statistics, orientation relations between parent and daughter phases, and transformation textures at different stages of the phase transition. This in turn will help in interpreting the geophysical observations. Details of the experimental and analytical approach used in this study will be given.

High-pressure/high-temperature polymorphs of energetic materials by first-principles simulations

NASA Astrophysics Data System (ADS)

Le, Nam; Schweigert, Igor

2017-06-01

Energetic molecular crystals exhibit complex phase diagrams that include solid-solid phase transitions, melting, and decomposition. Sorescu and Rice have recently demonstrated that first-principles molecular dynamics (MD) simulations based on dispersion-corrected density functional theory (DFT) can capture the α to γ phase transition in hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) on time scales of several picoseconds. Motivated by their work, we are using DFT-based MD to model the relative stability of solid phases in several molecular crystals. In this presentation, we report simulations of pentaerythritol tetranitrate (PETN) and 2,4,6-trinitrotoluene (TNT) under high pressures and temperatures and compare them with experimentally observed polymorphs. This work was supported by the U.S. Naval Research Laboratory via the National Research Council and by the Office of Naval Research through the U.S. Naval Research Laboratory.

Solid state characterization of E2101, a novel antispastic drug.

PubMed

Kushida, Ikuo; Ashizawa, Kazuhide

2002-10-01

E2101, a novel antispastic drug, was found to exist in at least two polymorphs that were confirmed by X-ray powder diffraction (XRD). These two species are designated forms I and II. The physicochemical and thermodynamic properties of these polymorphs were characterized by variable temperature XRD, thermal analysis, hygroscopicity measurements, and dissolution studies. The transition temperature was also estimated from the solubilities determined at various temperatures. The E2101 polymorphs were anhydrous and adsorbed little moisture under high humidity conditions. The melting onsets and heats of fusion for form I were 148.1 +/- 0.2 degrees C and 38.2 +/- 1.0 kJ/mol, respectively, and for form II were 139.8 +/- 0.4 degrees C and 35.2 +/- 0.5 kJ/mol, respectively. The intrinsic dissolution rate of form II in JP 2 medium was 1.5-fold faster than that of form I, corresponding to the rank order of the aqueous solubility and the enthalpy of fusion. Accordingly, form I was thought to be thermodynamically more stable than form II and thus suitable for further development. According to the thermal analysis and variable temperature XRD results, the recrystallization of form I occurred at approximately 145 degrees C after form II melted, however, no crystal transition behavior was observed below the lower melting point. The DSC thermograms at various heating rates and van't Hoff plots from the solubility studies indicated that the polymorphic pair would be monotropic. Copyright 2002 Wiley-Liss Inc. and the American Pharmaceutical Association

Cristobalite X-I: A bridge between low and high density silica polymorphs

NASA Astrophysics Data System (ADS)

Shelton, H.; Tiange, B.; Zurek, E.; Smith, J.; Dera, P.

2017-12-01

SiO2 is one of the most common compounds found on Earth. Despite its chemical simplicity, and because of its crystal chemical characteristics, SiO2 exhibits a complex phase diagram. SiO2 has a wide variety of thermodynamically stable crystalline phases, as well as numerous metastable crystalline and amorphous polymorphs. Many of the phase transition sequences that produce metastable phases of SiO2 are strongly path-dependent, where the rate of change controls the transition just as much as the final conditions. The elusive metastable polymorphs of SiO2 may provide a better understanding of the factors controlling its densification. On compression of α-cristobalite (the high temperature tetrahedral phase of SiO2) to pressures above 12 GPa, a new polymorph known as cristobalite X-I forms. Existence of cristobalite X-I has been known for several decades, however, consensus regarding the exact atomic arrangement has not yet been reached. The X-I phase constitutes an important step in the silica densification process, separating low-density tetrahedral framework structures from high-density octahedral polymorphs. It is unique in being the only non-quenchable high-density SiO2 phase, which reverts back to the tetrahedral low-density form on decompression at ambient temperature. Our new single crystal synchrotron X-ray diffraction experiments, with quasihydrostatic neon as the pressure medium, revealed the structure of this enigmatic phase to consist of octahedral silicate chains with 4-60°-2 zigzag chain geometry. This geometry has not been considered before, but is closely related to post-quartz, stishovite and seifertite. Density functional theory calculations support this observation, confirming the dynamic stability of the X-I arrangement and reasonably reproducing the pressure at which the transformation takes place. The enthalpy of cristobalite X-I is higher than stishovite and seifertite, but it is favored as a high-pressure successor of cristobalite due to a unique transformation pathway.

Entropic Anomaly Observed in Lipid Polymorphisms Induced by Surfactant Peptide SP-B(1-25).

PubMed

Tran, Nhi; Kurian, Justin; Bhatt, Avni; McKenna, Robert; Long, Joanna R

2017-10-05

The N-terminal 25 amino-acid residues of pulmonary surfactant protein B (SP-B 1-25 ) induces unusual lipid polymorphisms in a model lipid system, 4:1 DPPC/POPG, mirroring the lipid composition of native pulmonary surfactant. It is widely suggested that SP-B 1-25 -induced lipid polymorphisms within the alveolar aqueous subphase provide a structural platform for rapid lipid adsorption to the air-water interface. Here, we characterize in detail the phase behavior of DPPC and POPG in hydrated lipid assemblies containing therapeutic levels of SP-B 1-25 using 2 H and 31 P solid state NMR spectroscopy. The appearance of a previously observed isotropic lipid phase is found to be highly dependent on the thermal cycling of the samples. Slow heating of frozen samples leads to phase separation of DPPC into a lamellar phase whereas POPG lipids interact with the peptide to form an isotropic phase at physiologic temperature. Rapid heating of frozen samples to room temperature leads to strongly isotropic phase behavior for both DPPC and POPG lipids, with DPPC in exchange between isotropic and interdigitated phases. 31 P T 2 relaxation times confirm the isotropic phase to be consistent with a lipid cubic phase. The observed phases exhibit thermal stability up to physiologic temperature (37 °C) and are consistent with the formation of a ripple phase containing a large number of peptide-induced membrane structural defects enabling rapid transit of lipids between lipid lamellae. The coexistance of a lipid cubic phase with interdigitated lipids suggests a specific role for the highly conserved N-terminus of SP-B in stabilizing this unusual lipid polymorphism.

High pressure-temperature polymorphism of 1,1-diamino-2,2-dinitroethylene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, M. M.; Chellappa, R. S.; Liu, Z.

Here, 1,1-diamino-2,2-dinitroethylene (FOX-7) is a low sensitivity energetic material with performance comparable to commonly used secondary explosives such as RDX and HMX. At ambient pressure, FOX-7 exhibits complex polymorphism with at least three structurally distinct phases (α, β, and γ). In this study, we have investigated the high pressure-temperature stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra and corresponding differential scanning calorimetry (DSC) measurements confirmed the known α → β (~110 °C) and β → γ (~160 °C) structural phase transitions; as well as, indicated an additional transition γ → δ (~210 °C),more » with the δ phase being stable up to ~251 degree C prior to decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa, revealed a potential α → β transition that could occur as early as 180 degree C, while β → β+δ phase transition shifted to ~300 °C with suppression of γ phase. Decomposition was observed slightly above 325 °C at 0.9 GPa..« less

High pressure-temperature polymorphism of 1,1-diamino-2,2-dinitroethylene

DOE PAGES

Bishop, M. M.; Chellappa, R. S.; Liu, Z.; ...

2014-05-07

Here, 1,1-diamino-2,2-dinitroethylene (FOX-7) is a low sensitivity energetic material with performance comparable to commonly used secondary explosives such as RDX and HMX. At ambient pressure, FOX-7 exhibits complex polymorphism with at least three structurally distinct phases (α, β, and γ). In this study, we have investigated the high pressure-temperature stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra and corresponding differential scanning calorimetry (DSC) measurements confirmed the known α → β (~110 °C) and β → γ (~160 °C) structural phase transitions; as well as, indicated an additional transition γ → δ (~210 °C),more » with the δ phase being stable up to ~251 degree C prior to decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa, revealed a potential α → β transition that could occur as early as 180 degree C, while β → β+δ phase transition shifted to ~300 °C with suppression of γ phase. Decomposition was observed slightly above 325 °C at 0.9 GPa..« less

Shock induced polymorphic transition in quartz, carbon, and boron nitride

NASA Technical Reports Server (NTRS)

Tan, Hua; Ahrens, Thomas J.

1990-01-01

The model proposed by Ahrens (1988) to explain the mechanism of the polymorphism in silicates is revised, and the revised model is applied to the quartz/stishovite, graphite/diamond, and graphite-boron nitride (g-BN) phase transformations. In this model, a key assumption is that transformation to a high-density amorphous or possibly liquid phase which rapidly crystallized to the high-pressure phase is triggered by the high temperatures in the shear band and upon crossing the metastable extension of a melting curve. Good agreement between the calcualted results and published data is obtained. The present theory predicts the standard entropy for cubic BN to be 0.4-0.5 J/g K.

Structure of organic solids at low temperature and high pressure.

PubMed

Lee, Rachael; Howard, Judith A K; Probert, Michael R; Steed, Jonathan W

2014-07-07

This tutorial review looks at structural and supramolecular chemistry of molecular solids under extreme conditions, and introduces the instrumentation and facilities that enable single crystal diffraction studies on molecular crystals at both high pressure and low temperature. The equipment used for crystallography under extreme conditions is explored, particularly pressure cells such as the diamond anvil cell, and their mechanism of action, as well as the cryogenic apparatus which allows materials to be cooled to significantly low temperatures. The review also covers recent advances in the structural chemistry of molecular solids under extreme conditions with an emphasis on the use of single crystal crystallography in high pressure and low temperature environments to probe polymorphism and supramolecular interactions.

Exploring the high-pressure behavior of the three known polymorphs of BiPO{sub 4}: Discovery of a new polymorph

DOE Office of Scientific and Technical Information (OSTI.GOV)

Errandonea, D., E-mail: daniel.errandonea@uv.es; García-Domene, B.; Gomis, O.

We have studied the structural behavior of bismuth phosphate under compression. We performed x-ray powder diffraction measurements up to 31.5 GPa and ab initio calculations. Experiments were carried out on different polymorphs: trigonal (phase I) and monoclinic (phases II and III). Phases I and III, at low pressure (P < 0.2–0.8 GPa), transform into phase II, which has a monazite-type structure. At room temperature, this polymorph is stable up to 31.5 GPa. Calculations support these findings and predict the occurrence of an additional transition from the monoclinic monazite-type to a tetragonal scheelite-type structure (phase IV). This transition was experimentally found after the simultaneous applicationmore » of pressure (28 GPa) and temperature (1500 K), suggesting that at room temperature the transition might by hindered by kinetic barriers. Calculations also predict an additional phase transition at 52 GPa, which exceeds the maximum pressure achieved in the experiments. This transition is from phase IV to an orthorhombic barite-type structure (phase V). We also studied the axial and bulk compressibility of BiPO{sub 4}. Room-temperature pressure-volume equations of state are reported. BiPO{sub 4} was found to be more compressible than isomorphic rare-earth phosphates. The discovered phase IV was determined to be the less compressible polymorph of BiPO{sub 4}. On the other hand, the theoretically predicted phase V has a bulk modulus comparable with that of monazite-type BiPO{sub 4}. Finally, the isothermal compressibility tensor for the monazite-type structure is reported at 2.4 GPa showing that the direction of maximum compressibility is in the (0 1 0) plane at approximately 15° (21°) to the a axis for the case of our experimental (theoretical) study.« less

Characterization of Perovskite Films Grown by a Novel Low-Temperature Process for Uncooled IR Detector Applications

DTIC Science & Technology

2008-12-01

hydrolysis and polycondensation of molecular precursors in vitro to form SiO2, anatase-TiO2, and - Ga2O3 under very mild conditions, whereas...forming high temperature crystalline polymorphs of TiO2 and Ga2O3 lies in kinetically controlled, slow catalytic hydrolysis and growth. In an

Inferring thermodynamic stability relationship of polymorphs from melting data.

PubMed

Yu, L

1995-08-01

This study investigates the possibility of inferring the thermodynamic stability relationship of polymorphs from their melting data. Thermodynamic formulas are derived for calculating the Gibbs free energy difference (delta G) between two polymorphs and its temperature slope from mainly the temperatures and heats of melting. This information is then used to estimate delta G, thus relative stability, at other temperatures by extrapolation. Both linear and nonlinear extrapolations are considered. Extrapolating delta G to zero gives an estimation of the transition (or virtual transition) temperature, from which the presence of monotropy or enantiotropy is inferred. This procedure is analogous to the use of solubility data measured near the ambient temperature to estimate a transition point at higher temperature. For several systems examined, the two methods are in good agreement. The qualitative rule introduced this way for inferring the presence of monotropy or enantiotropy is approximately the same as The Heat of Fusion Rule introduced previously on a statistical mechanical basis. This method is applied to 96 pairs of polymorphs from the literature. In most cases, the result agrees with the previous determination. The deviation of the calculated transition temperatures from their previous values (n = 18) is 2% on average and 7% at maximum.

Recrystallization of fluconazole using the supercritical antisolvent (SAS) process.

PubMed

Park, Hee Jun; Kim, Min-Soo; Lee, Sibeum; Kim, Jeong-Soo; Woo, Jong-Soo; Park, Jeong-Sook; Hwang, Sung-Joo

2007-01-10

The supercritical antisolvent (SAS) process was used to modify solid state characteristics of fluconazole. Fluconazole was recrystallized at various temperatures (60-80 degrees C) and pressures (8-16MPa) using dichloromethane (DCM) as a solvent. Acetone and ethanol were also employed as solvents. The fluconazole polymorphs prepared by the SAS process were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Furthermore, the equilibrium solubility of the samples in aqueous solution was determined. Fluconazole anhydrate form I was obtained at low temperature (40 degrees C) and anhydrate form II was obtained at high temperature (80 degrees C). The variation of pressure during the SAS process may influence the preferred orientation. Anhydrate forms I and II were also obtained using various solvents. Therefore, it was shown that solid state characteristics of fluconazole, including the polymorphic form and preferred orientation, can be controlled by changing operating conditions of the SAS process such as temperature, pressure, and solvent.

Polymorphisms in carcinogen metabolism enzymes, fish intake, and risk of prostate cancer

PubMed Central

Stern, Mariana C.

2012-01-01

Cooking fish at high temperature can produce potent carcinogens such as heterocyclic amines and polycyclic aromatic hydrocarbons. The effects of these carcinogens may undergo modification by the enzymes responsible for their detoxification and/or activation. In this study, we investigated genetic polymorphisms in nine carcinogen metabolism enzymes and their modifying effects on the association between white or dark fish consumption and prostate cancer (PCA) risk. We genotyped 497 localized and 936 advanced PCA cases and 760 controls from the California Collaborative Case–Control Study of Prostate Cancer. Three polymorphisms, EPHX1 Tyr113His, CYP1B1 Leu432Val and GSTT1 null/present, were associated with localized PCA risk. The PTGS2 765 G/C polymorphism modified the association between white fish consumption and advanced PCA risk (interaction P 5 0.002), with high white fish consumption being positively associated with risk only among carriers of the C allele. This effect modification by PTGS2 genotype was stronger when restricted to consumption of well-done white fish (interaction P 5 0.021). These findings support the hypotheses that changes in white fish brought upon by high-temperature cooking methods, such as carcinogen accumulation and/or fatty acid composition changes, may contribute to prostate carcinogenesis. However, the gene–diet interactions should be interpreted with caution given the limited sample size. Thus, our findings require further validation with additional studies. Abbreviations: AA African American; BMI body mass index; CI confidence interval; CNV copy number variant; EPIC European Prospective Investigation into Cancer and Nutrition; HCA heterocyclic amine; HCFA Health Care Financing Administration; LAC Los Angeles county; MAF minor allele frequency; NHW non-Hispanic White; OR odds ratio; PAH polycyclic aromatic hydrocarbon; PCA prostate cancer; PTGS2 prostaglandin- endoperoxide synthase 2; PUFA polyunsaturated fatty acids; RDD random-digit dialing; SEER Surveillance, Epidemiology, and End Result; SES socio-economic status; SFBA San Francisco Bay Area; SNP single-nucleotide polymorphism PMID:22610071

High-pressure polymorphism of As2S3 and new AsS2 modification with layered structure

NASA Astrophysics Data System (ADS)

Bolotina, N. B.; Brazhkin, V. V.; Dyuzheva, T. I.; Katayama, Y.; Kulikova, L. F.; Lityagina, L. V.; Nikolaev, N. A.

2014-01-01

At normal pressure, the As2S3 compound is the most stable equilibrium modification with unique layered structure. The possibility of high-pressure polymorphism of this substance remains questionable. Our research showed that the As2S3 substance was metastable under pressures P > 6 GPa decomposing into two high-pressure phases: As2S3 → AsS2 + AsS. New AsS2 phase can be conserved in the single crystalline form in metastable state at room pressure up to its melting temperature (470 K). This modification has the layered structure with P1211 monoclinic symmetry group; the unit-cell values are a = 7.916(2) Å, b = 9.937(2) Å, c = 7.118(1) Å, β = 106.41° ( Z = 8, density 3.44 g/cm3). Along with the recently studied AsS high-pressure modification, the new AsS2 phase suggests that high pressure polymorphism is a very powerful tool to create new layered-structure phases with "wrong" stoichiometry.

Dynamics of Polymorphic Transformations in Palm Oil, Palm Stearin and Palm Kernel Oil Characterized by Coupled Powder XRD-DSC.

PubMed

Zaliha, Omar; Elina, Hishamuddin; Sivaruby, Kanagaratnam; Norizzah, Abd Rashid; Marangoni, Alejandro G

2018-06-01

The in situ polymorphic forms and thermal transitions of refined, bleached and deodorized palm oil (RBDPO), palm stearin (RBDPS) and palm kernel oil (RBDPKO) were investigated using coupled X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results indicated that the DSC onset crystallisation temperature of RBDPO was at 22.6°C, with a single reflection at 4.2Å started to appear from 23.4 to 17.1°C, and were followed by two prominent exothermic peaks at 20.1°C and 8.5°C respectively. Further cooling to -40°C leads to the further formation of a β'polymorph. Upon heating, a of β'→βtransformation was observed between 32.1 to 40.8°C, before the sample was completely melted at 43.0°C. The crystallization onset temperature of RBDPS was 44.1°C, with the appearance of the α polymorph at the same temperature as the appearance of the first sharp DSC exothermic peak. This quickly changed from α→β´ in the range 25 to 21.7°C, along with the formation of a small β peak at -40°C. Upon heating, a small XRD peak for the β polymorph was observed between 32.2 to 36.0°C, becoming a mixture of (β´+ β) between 44.0 to 52.5°C. Only the β polymorph survived further heating to 59.8°C. For RBDPKO, the crystallization onset temperature was 11.6°C, with the formation of a single sharp exothermic peak at 6.5°C corresponding to the β' polymorphic form until the temperature reached -40°C. No transformation of the polymorphic form was observed during the melting process of RBDPKO, before being completely melted at 33.2°C. This work has demonstrated the detailed dynamics of polymorphic transformations of PKO and PS, two commercially important hardstocks used widely by industry and will contribute to a greater understanding of their crystallization and melting dynamics.

Synthesis and magnetic properties of the high-pressure scheelite-type GdCrO{sub 4} polymorph

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dos santos-Garcia, A.J., E-mail: adossant@quim.ucm.es; Climent-Pascual, E.; Gallardo-Amores, J.M.

The scheelite-type polymorph of GdCrO{sub 4} has been obtained from the corresponding zircon-type compound under high pressure and temperature conditions, namely 4 GPa and 803 K. The crystal structure has been determined by X-ray powder diffraction. This GdCrO{sub 4} scheelite crystallizes in a tetragonal symmetry with space group I4{sub 1}/a (No. 88, Z=4), a=5.0501(1) A, c=11.4533(2) A and V=292.099(7) A{sup 3}. The thermal decomposition leads to the formation of the zircon-polymorph as intermediate phase at 773 K to end in the corresponding GdCrO{sub 3} distorted perovskite-structure at higher temperatures. Magnetic susceptibility and magnetization measurements suggest the existence of long-range antiferromagneticmore » interactions which have been also confirmed from specific heat measurements. Neutron powder diffraction data reveal the simultaneous antiferromagnetic Gd{sup 3+} and Cr{sup 5+} ordering in the scheelite-type GdCrO{sub 4} with a T{sub N}{approx}20 K. The magnetic propagation vector was found to be k=(0 0 0). Combined with group theory analysis, the best neutron powder diffraction fit was obtained with a collinear antiferromagnetic coupling in which the m{sub Cr{sup 5}{sup +}} and m{sub Gd{sup 3}{sup +}} magnetic moments are confined in the tetragonal basal plane according to the mixed representation {Gamma}{sub 6} Circled-Plus {Gamma}{sub 8}. Thermal decomposition of the GdCrO{sub 4} high pressure polymorph, from the scheelite-type through the zircon-type structure as intermediate to end in the GdCrO{sub 3} perovskite. Highlights: Black-Right-Pointing-Pointer New high pressure GdCrO{sub 4} polymorph crystallizing in the scheelite type structure. Black-Right-Pointing-Pointer It is an antiferromagnet with a metamagnetic transition at low magnetic fields. Black-Right-Pointing-Pointer We have determined its magnetic structure from powder neutron diffraction data. Black-Right-Pointing-Pointer Otherwise, the room pressure zircon-polymorph is a ferromagnet. Black-Right-Pointing-Pointer The paper will be a great contribution in the study of 3d-4f magnetic interactions.« less

Polymorphism of Alprazolam (Xanax): a review of its crystalline phases and identification, crystallographic characterization, and crystal structure of a new polymorph (form III).

PubMed

de Armas, Héctor Novoa; Peeters, Oswald M; Van den Mooter, Guy; Blaton, Norbert

2007-05-01

A new polymorphic form of Alprazolam (Xanax), 8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo-[4,3-alpha][1,4]benzodiazepine, C(17)H(13)ClN(4), has been investigated by means of X-ray powder diffraction (XRPD), single crystal X-ray diffraction, and differential scanning calorimetry (DSC). This polymorphic form (form III) was obtained during DSC experiments after the exothermic recrystallization of the melt of form I. The crystal unit cell dimensions for form III were determined from diffractometer methods. The monoclinic unit cell found for this polymorph using XRPD after indexing the powder diffractogram was confirmed by the cell parameters obtained from single crystal X-ray diffractometry on a crystal isolated from the DSC pans. The single crystal unit cell parameters are: a = 28.929(9), b = 13.844(8), c = 7.361(3) angstroms, beta = 92.82(3) degrees , V = 2944(2) angstroms(3), Z = 8, space group P2(1) (No.4), Dx = 1.393 Mg/m(3). The structure obtained from single crystal X-ray diffraction was used as initial model for Rietveld refinement on the powder diffraction data of form III. The temperature phase transformations of alprazolam were also studied using high temperature XRPD. A review of the different phases available in the Powder Diffraction File (PDF) database for this drug is described bringing some clarification and corrections. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Thermodynamic Stability Analysis of Tolbutamide Polymorphs and Solubility in Organic Solvents.

PubMed

Svärd, Michael; Valavi, Masood; Khamar, Dikshitkumar; Kuhs, Manuel; Rasmuson, Åke C

2016-06-01

Melting temperatures and enthalpies of fusion have been determined by differential scanning calorimetry (DSC) for 2 polymorphs of the drug tolbutamide: FI(H) and FV. Heat capacities have been determined by temperature-modulated DSC for 4 polymorphs: FI(L), FI(H), FII, FV, and for the supercooled melt. The enthalpy of fusion of FII at its melting point has been estimated from the enthalpy of transition of FII into FI(H) through a thermodynamic cycle. Calorimetric data have been used to derive a quantitative polymorphic stability relationship between these 4 polymorphs, showing that FII is the stable polymorph below approximately 333 K, above which temperature FI(H) is the stable form up to its melting point. The relative stability of FV is well below the other polymorphs. The previously reported kinetic reversibility of the transformation between FI(L) and FI(H) has been verified using in situ Raman spectroscopy. The solid-liquid solubility of FII has been gravimetrically determined in 5 pure organic solvents (methanol, 1-propanol, ethyl acetate, acetonitrile, and toluene) over the temperature range 278 to 323 K. The ideal solubility has been estimated from calorimetric data, and solution activity coefficients at saturation in the 5 solvents determined. All solutions show positive deviation from Raoult's law, and all van't Hoff plots of solubility data are nonlinear. The solubility in toluene is well below that observed in the other investigated solvents. Solubility data have been correlated and extrapolated to the melting point using a semiempirical regression model. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Transitiometric analysis of solid II/solid I transition in anhydrous theophylline.

PubMed

Legendre, Bernard; Randzio, Stanislaw L

2007-10-01

For the first time, with the use of a high sensitivity, low heating rate, scanning transitiometry, it was possible to distinguish and characterise the polymorphic equilibrium transition between forms II and I in anhydrous theophylline. In this manner it was univocally proved, that forms II and I in theophylline are enantiotropically related. The temperature and enthalpy for that transition are as follows: T(trs)(II/I)=536.8+/-2.2K; Delta(trs)H(II/I)=1.99+/-0.09 kJ/mol. Making use of advantages of very slow heating rate and of a high energetic sensitivity of the transitiometer it was possible to observe in detail the polymorphic transition followed by melting of high temperature form I and to stop the solid I-liquid transition at a desired point of equilibrium. Such a solid I-liquid equilibrium could be stabilised and then displaced back to the crystallisation of form I with an adequate use of a precise temperature programming. In such a way a pure single phase of form I of theophylline was prepared. This fact was confirmed by X-ray powder diffraction patterns and calorimetric traces of fusion of the crystallised product. The temperature and enthalpy of the form I-liquid transition are as follows: T(fus)(I)=546.5+/-0.2K and Delta(fus)H(I)=29.37+/-0.29 kJ/mol.

Changes in dark chocolate volatiles during storage.

PubMed

Nightingale, Lia M; Cadwallader, Keith R; Engeseth, Nicki J

2012-05-09

Chocolate storage is critical to the quality of the final product. Inadequate storage, especially with temperature fluctuations, may lead to a change in crystal structure, which may eventually cause fat bloom. Bloom is the main cause of quality loss in the chocolate industry. The impact of various storage conditions on the flavor quality of dark chocolate was determined. Dark chocolate was stored in different conditions leading to either fat or sugar bloom and analyzed at 0, 4, and 8 weeks of storage. Changes in chocolate flavor were determined by volatile analysis and descriptive sensory evaluation. Results were analyzed by analysis of variance (ANOVA), cluster analysis, principal component analysis (PCA), and linear partial least-squares regression analysis (PLS). Volatile concentration and loss were significantly affected by storage conditions. Chocolates stored at high temperature were the most visually and texturally compromised, but volatile concentrations were affected the least, whereas samples stored at ambient, frozen, and high relative humidity conditions had significant volatile loss during storage. It was determined that high-temperature storage caused a change in crystal state due to the polymorphic shift to form VI, leading to an increase in sample hardness. Decreased solid fat content (SFC) during high-temperature storage increased instrumentally determined volatile retention, although no difference was detected in chocolate flavor during sensory analysis, possibly due to instrumental and sensory sampling techniques. When all instrumental and sensory data had been taken into account, the storage condition that had the least impact on texture, surface roughness, grain size, lipid polymorphism, fat bloom formation, volatile concentrations, and sensory attributes was storage at constant temperature and 75% relative humidity.

Multilocus adaptation associated with heat resistance in reef-building corals.

PubMed

Bay, Rachael A; Palumbi, Stephen R

2014-12-15

The evolution of tolerance to future climate change depends on the standing stock of genetic variation for resistance to climate-related impacts, but genes contributing to climate tolerance in wild populations are poorly described in number and effect. Physiology and gene expression patterns have shown that corals living in naturally high-temperature microclimates are more resistant to bleaching because of both acclimation and fixed effects, including adaptation. To search for potential genetic correlates of these fixed effects, we genotyped 15,399 single nucleotide polymorphisms (SNPs) in 23 individual tabletop corals, Acropora hyacinthus, within a natural temperature mosaic in backreef lagoons on Ofu Island, American Samoa. Despite overall lack of population substructure, we identified 114 highly divergent SNPs as candidates for environmental selection, via multiple stringent outlier tests, and correlations with temperature. Corals from the warmest reef location had higher minor allele frequencies across these candidate SNPs, a pattern not seen for noncandidate loci. Furthermore, within backreef pools, colonies in the warmest microclimates had a higher number and frequency of alternative alleles at candidate loci. These data suggest mild selection for alternate alleles at many loci in these corals during high heat episodes and possible maintenance of extensive polymorphism through multilocus balancing selection in a heterogeneous environment. In this case, a natural population harbors a reservoir of alleles preadapted to high temperatures, suggesting potential for future evolutionary response to climate change. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterization of two polymorphs of salmeterol xinafoate crystallized from supercritical fluids.

PubMed

Tong, H H; Shekunov, B Y; York, P; Chow, A H

2001-06-01

To characterize two polymorphs of salmeterol xinafoate (SX-I and SX-II) produced by supercritical fluid crystallization. SX-I and SX-II were crystallized as fine powders using Solution Enhanced Dispersion by Supercritical Fluids (SEDS). The two polymorphs and a reference micronized SX sample (MSX) were characterized using powder X-ray diffractometry (PXRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), aqueous solubility (and dissolution) determination at 5-40 degrees C, BET adsorption analysis, and inverse gas chromatography (IGC). Compared with SX-I, SX-II exhibited a lower enthalpy of fusion, a higher equilibrium solubility, a higher intrinsic dissolution rate, a lower enthalpy of solution (based on van't Hoff solubility plots), and a different FTIR spectrum (reflecting differences in intermolecular hydrogen bonding). Solubility ratio plot yielded a transition temperature (-99 degrees C) below the melting points of both polymorphs. MSX showed essentially the same crystal form as SX-I (confirmed by PXRD and FTIR), but a distinctly different thermal behaviour. Mild trituration of SX-I afforded a similar DSC profile to MSX while prolonged grinding of SX-I gave rise to an endotherm at -109 degrees C, corresponding to solid-solid transition of SX-I to SX-II. Surface analysis of MSX, SX-I, and SX-II by IGC revealed significant differences in surface free energy in terms of both dispersive (nonpolar) interactions and specific (polar) acid-base properties. The SEDS-processed SX-I and SX-II display high polymorphic purity and distinctly different physical and surface properties. The polymorphs are related enantiotropically with SX-I being the thermodynamically stable form at room temperature.

Polymorphisms in base excision repair genes as colorectal cancer risk factors and modifiers of the effect of diets high in red meat.

PubMed

Brevik, Asgeir; Joshi, Amit D; Corral, Román; Onland-Moret, N Charlotte; Siegmund, Kimberly D; Le Marchand, Loïc; Baron, John A; Martinez, Maria Elena; Haile, Robert W; Ahnen, Dennis J; Sandler, Robert S; Lance, Peter; Stern, Mariana C

2010-12-01

A diet high in red meat is an established colorectal cancer (CRC) risk factor. Carcinogens generated during meat cooking have been implicated as causal agents and can induce oxidative DNA damage, which elicits repair by the base excision repair (BER) pathway. Using a family-based study, we investigated the role of polymorphisms in 4 BER genes (APEX1 Gln51His, Asp148Glu; OGG1 Ser236Cys; PARP Val742Ala; and XRCC1 Arg194Trp, Arg280His, Arg399Gln) as potential CRC risk factors and modifiers of the association between diets high in red meat or poultry and CRC risk. We tested for gene-environment interactions using case-only analyses (n = 577) and compared statistically significant results with those obtained using case-unaffected sibling comparisons (n = 307 sibships). Carriers of the APEX1 codon 51 Gln/His genotype had a reduced CRC risk compared with carriers of the Gln/Gln genotype (odds ratio (OR) = 0.15, 95% CI = 0.03-0.69, P = 0.015). The association between higher red meat intake (>3 servings per week) and CRC was modified by the PARP Val762Ala single-nucleotide polymorphisms (SNP; case-only interaction P = 0.026). This SNP also modified the association between higher intake of high-temperature cooked red meat (case-only interaction P = 0.0009). We report evidence that the BER pathway PARP gene modifies the association of diets high in red meat cooked at high temperatures with risk of CRC. Our findings suggest a contribution to colorectal carcinogenesis of free radical damage as one of the possible harmful effects of a diet high in red meat. ©2010 AACR.

Lithium ion conduction in sol-gel synthesized LiZr2(PO4)3 polymorphs

NASA Astrophysics Data System (ADS)

Kumar, Milind; Yadav, Arun Kumar; Anita, Sen, Somaditya; Kumar, Sunil

2018-04-01

Safety issue associated with the high flammability and volatility of organic electrolytes used in commercial rechargeable lithium ion batteries has led to significant attention to ceramic-based solid electrolytes. In the present study, lithium ion conduction in two polymorphs of LiZr2(PO4)3 synthesized via the sol-gel route has been investigated. Rietveld refinement of room temperature X-ray diffraction data of LiZr2(PO4)3 powders calcined at 900 °C and 1300 °C confirmed these to be the monoclinic phase with P21/n structure and rhombohedral phase with R3¯c structure, respectively. Increase in calcination temperature and resultant phase transformation improved the room temperature conductivity from 2.27×10-6 ohm-1m-1 for the monoclinic phase to 1.41×10-4 ohm-1m-1 for rhombohedral phase. Temperature dependence of conductivity was modeled using Arrhenius law and activation energy of ˜ 0.59 eV (for monoclinic phase) and ˜0.50 eV (for rhombohedral phase) were obtained.

Diffusion-controlled and "diffusionless" crystal growth near the glass transition temperature: relation between liquid dynamics and growth kinetics of seven ROY polymorphs.

PubMed

Sun, Ye; Xi, Hanmi; Ediger, M D; Richert, Ranko; Yu, Lian

2009-08-21

The liquid dynamics of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile, named ROY for its red, orange, and yellow crystal polymorphs, was characterized by dielectric spectroscopy and differential scanning calorimetry. Four of these polymorphs show fast "diffusionless" crystal growth at low temperatures while three others do not. ROY was found to be a typical fragile organic liquid. Its alpha relaxation process has time-temperature superposition symmetry across the viscous range (tau(alpha)=100 s-100 ns) with the width of the relaxation peak characterized by a constant beta(KWW) of 0.73. No secondary relaxation peak was observed, even with glasses made by fast quenching. For the polymorphs not showing fast crystal growth in the glassy state, the growth rate has a power-law relation with tau(alpha), u proportional to tau(alpha)(-xi), where xi approximately = 0.7. For the polymorphs showing fast crystal growth in the glassy state, the growth is so fast near and below the glass transition temperature T(g) that thousands of molecular layers can be added to the crystalline phase during one structural relaxation time of the liquid. In the glassy state, this mode of growth slows slightly over time. This slowdown is not readily explained by the effect of physical aging on the thermodynamic driving force of crystallization, the glass vapor pressure, or the rate of structural relaxation. This study demonstrates that from the same liquid or glass, the growth of some polymorphs is accurately described as being limited by the rate of structural relaxation or bulk diffusion, whereas the growth of other polymorphs is too fast to be under such control.

Structural study of polymorphism in methylprednisolone aceponate

NASA Astrophysics Data System (ADS)

Knyazev, A. V.; Somov, N. V.; Shipilova, A. S.; Gusarova, E. V.; Knyazeva, S. S.; Stepanova, O. V.; Chuprunov, E. V.

2017-08-01

The crystal structures of methylprednisolone aceponate were determined by X-ray diffraction analysis at temperatures 90 K and 150 K: space group P212121, a = 14.8592(2), b = 19.6844(5), c = 26.1626(4) Å, Z = 12; R = 0.0598 (T = 90 K); space group P212121, a = 6.57348(14), b = 14.8295(3), c = 26.2214(5) Å, Z = 4; R = 0.0518 (T = 150 K). Features of structural changes in the phase transition were revealed. The abrupt change in the unit cell parameters in the phase transition was shown by low-temperature X-ray powder. The methods of degree of invariance of crystal electron density and molecular Voronoi-Dirichlet polyhedra were used for the analysis of polymorphism in methylprednisolone aceponate. The atomic structure at 90 K have a translational pseudosymmetry of electron density η = 0.329(1). The decrease of number of intermolecular contacts in the high-temperature modification due to rupture of intermolecular non-valence contacts C/O was observed.

Structure-energy relationship in barbituric acid: a calorimetric, computational, and crystallographic study.

PubMed

Roux, María Victoria; Temprado, Manuel; Notario, Rafael; Foces-Foces, Concepción; Emel'yanenko, Vladimir N; Verevkin, Sergey P

2008-08-14

This paper reports the value of the standard (p(o) = 0.1 MPa) molar enthalpy of formation in the gas phase at T = 298.15 K for barbituric acid. The enthalpies of combustion and sublimation were measured by static bomb combustion calorimetry and transference (transpiration) method in a saturated N2 stream and a gas-phase enthalpy of formation value of -(534.3 +/- 1.7) kJ x mol(-1) was determined at T = 298.15 K. G3-calculated enthalpies of formation are in very good agreement with the experimental value. The behavior of the sample as a function of the temperature was studied by differential scanning calorimetry, and a new polymorph of barbituric acid at high temperature was found. In the solid state, two anhydrous forms are known displaying two out of the six hydrogen-bonding patterns observed in the alkyl/alkenyl derivatives retrieved from the Cambridge Crystallographic Database. The stability of these motifs has been analyzed by theoretical calculations. X-ray powder diffraction technique was used to establish to which polymorphic form corresponds to the commercial sample used in this study and to characterize the new form at high temperature.

Origin of the magnetic transition at 100 K in ɛ-Fe2O3 nanoparticles studied by x-ray absorption fine structure spectroscopy

NASA Astrophysics Data System (ADS)

López-Sánchez, J.; Muñoz-Noval, A.; Castellano, C.; Serrano, A.; del Campo, A.; Cabero, M.; Varela, M.; Abuín, M.; de la Figuera, J.; Marco, J. F.; Castro, G. R.; Rodríguez de la Fuente, O.; Carmona, N.

2017-12-01

The current study unveils the structural origin of the magnetic transition of the ɛ-Fe2O3 polymorph from an incommensurate magnetic order to a collinear ferrimagnetic state at low temperature. The high crystallinity of the samples and the absence of other iron oxide polymorphs have allowed us to carry out temperature-dependent x-ray absorption fine structure spectroscopy experiments out. The deformation of the structure is followed by the Debye-Waller factor for each selected Fe-O and Fe-Fe sub-shell. For nanoparticle sizes between 7 and 15 nm, the structural distortions between the Fete and Fe-D1oc sites are localized in a temperature range before the magnetic transition starts. On the contrary, the inherent interaction between the other sub-shells (named Fe-O1,2 and Fe-Fe1) provokes cooperative magneto-structural changes in the same temperature range. This means that the Fete with Fe-D1oc polyhedron interaction seems to be uncoupled with temperature dealing with these nanoparticle sizes wherein the structural distortions are likely moderate due to surface effects.

Crystal structure, chemical expansion and phase stability of HoMnO{sub 3} at high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selbach, Sverre M., E-mail: selbach@material.ntnu.no; Nordli Lovik, Amund; Bergum, Kristin

Anisotropic thermal and chemical expansion of hexagonal HoMnO{sub 3} was investigated by high temperature X-ray diffraction in inert (N{sub 2}) and oxidizing (air) atmospheres up to 1623 K. A second order structural phase transition directly from P6{sub 3}cm to P6{sub 3}/mmc was found at 1298{+-}4 K in N{sub 2} atmosphere, and 1318{+-}4 K in air. For the low temperature polymorph P6{sub 3}cm the contraction of the c-axis was more rapid in inert than in oxidizing atmosphere. The c-axis of the P6{sub 3}/mmc polymorph of HoMnO{sub 3} displayed anomalously high expansion above 1400 K, which is discussed in relation to chemicalmore » expansion caused by point defects. The a-axis expanded stronger in inert than oxidizing atmosphere. Anisotropic chemical and thermal expansion of the P6{sub 3}cm phase of YMnO{sub 3} in N{sub 2}, air and O{sub 2} atmospheres was found to be qualitatively similar to that of HoMnO{sub 3}. Decomposition of hexagonal HoMnO{sub 3} by two different processes occurs in oxidizing atmosphere above {approx}1200 K followed by nucleation and growth of the perovskite polymorph of HoMnO{sub 3}. A rapid, reconstructive transition from the perovskite back to the hexagonal polymorph was observed in situ at 1623 K upon reduction of the partial pressure of oxygen. A phase stability diagram of the hexagonal and orthorhombic polymorphs is proposed. Finally, distinctly non-linear electrical conductivity was observed for both HoMnO{sub 3} and YMnO{sub 3} in oxidizing atmosphere between 555 and 630 K, and shown to be associated with excess oxygen. - Graphical abstract: Chemical expansion of hexagonal HoMnO{sub 3} is observed during HTXRD in different pO{sub 2}. Oxidizing atmosphere favors the competing perovskite polymorph. Electrical conductivity anomalies related to excess oxygen are found at 550-630 K. Highlights: Black-Right-Pointing-Pointer Thermal evolution of crystal structure of HoMnO{sub 3} studied up to 1623 K in air and N{sub 2}. Black-Right-Pointing-Pointer Anisotropic chemical expansion of HoMnO{sub 3} and YMnO{sub 3} in N{sub 2}, air and O{sub 2}. Black-Right-Pointing-Pointer Hexagonal phase destabilized with respect to perovskite in oxidizing atmosphere. Black-Right-Pointing-Pointer Crystal structure and phase stability discussed in terms of point defect chemistry. Black-Right-Pointing-Pointer Electrical conductivity anomalies associated with excess oxygen at 550-630 K.« less

Polymorphic Transitions in Cerium-Substituted Zirconolite (CaZrTi 2O 7)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Braeden M.; Sundaram, S. K.; Misture, Scott T.

Compounds with the formulae CaZr 1–xCe xTi 2O 7 with x = 0.1–0.5 were synthesized by solid state reaction. Cerium was used as a surrogate for actinide elements. A transition from the 2M polymorph to the 4M polymorph (expanded unit cell due to cation ordering) in zirconolite was observed with increasing cerium content. The presence of both tri- and tetravalent Ce, contrary to formulation, was confirmed using X-ray absorption near edge spectroscopy, suggesting substitution on both Ca and Zr sites. Sintering was carried out via spark plasma sintering, during which the perovskite phase (Ca 0.4Ce 0.4TiO 3) was stabilized duemore » to the reducing conditions of this technique. Scanning electron microscopy and energy dispersive spectrometry revealed that the 2M polymorph was dilute in Ce content in comparison to the 4M-zirconolite. High temperature X-ray diffraction was used to detail the kinetics of perovskite to zirconolite transition. It was found that CaCeTi 2O 7 (cubic pyrochlore) formed as an intermediate phase during the transition. Lastly, our results show that a transition from 2M- to 4M-zirconolite occurs with increasing Ce content and can be controlled by adjusting the P O2 and the heat treatment temperature.« less

Polymorphic Transitions in Cerium-Substituted Zirconolite (CaZrTi 2O 7)

DOE PAGES

Clark, Braeden M.; Sundaram, S. K.; Misture, Scott T.

2017-07-19

Compounds with the formulae CaZr 1–xCe xTi 2O 7 with x = 0.1–0.5 were synthesized by solid state reaction. Cerium was used as a surrogate for actinide elements. A transition from the 2M polymorph to the 4M polymorph (expanded unit cell due to cation ordering) in zirconolite was observed with increasing cerium content. The presence of both tri- and tetravalent Ce, contrary to formulation, was confirmed using X-ray absorption near edge spectroscopy, suggesting substitution on both Ca and Zr sites. Sintering was carried out via spark plasma sintering, during which the perovskite phase (Ca 0.4Ce 0.4TiO 3) was stabilized duemore » to the reducing conditions of this technique. Scanning electron microscopy and energy dispersive spectrometry revealed that the 2M polymorph was dilute in Ce content in comparison to the 4M-zirconolite. High temperature X-ray diffraction was used to detail the kinetics of perovskite to zirconolite transition. It was found that CaCeTi 2O 7 (cubic pyrochlore) formed as an intermediate phase during the transition. Lastly, our results show that a transition from 2M- to 4M-zirconolite occurs with increasing Ce content and can be controlled by adjusting the P O2 and the heat treatment temperature.« less

Photobacterium damselae ssp. piscicida: detection by direct amplification of 16S rRNA gene sequences and genotypic variation as determined by amplified fragment length polymorphism (AFLP).

PubMed

Kvitt, H; Ucko, M; Colorni, A; Batargias, C; Zlotkin, A; Knibb, W

2002-04-05

A PCR protocol for the rapid diagnosis of fish 'pasteurellosis' based on 16S rRNA gene sequences was developed. The procedure combines low annealing temperature that detects low titers of Photobacterium damselae but also related species, and high annealing temperature for the specific identification of P. damselae directly from infected fish. The PCR protocol was validated on 19 piscine isolates of P. damselae ssp. piscicida from different geographic regions (Japan, Italy, Spain, Greece and Israel), on spontaneously infected sea bream Sparus aurata and sea bass Dicentrarchus labrax, and on closely related American Type Culture Collection (ATCC) reference strains. PCR using high annealing temperature (64 degrees C) discriminated between P. damselae and closely related reference strains, including P. histaminum. Sixteen isolates of P. damselae ssp. piscicida, 2 P. damselae ssp. piscicida reference strains and 1 P. damselae ssp. damselae reference strain were subjected to Amplified Fragment Length Polymorphism (AFLP) analysis, and a similarity matrix was produced. Accordingly, the Japanese isolates of P. damselae ssp. piscicida were distinguished from the Mediterranean/European isolates at a cut-off value of 83% similarity. A further subclustering at a cut-off value of 97% allowed discrimination between the Israeli P. damselae ssp. piscicida isolates and the other Mediterranean/European isolates. The combination of PCR direct amplification and AFLP provides a 2-step procedure, where P. damselae is rapidly identified at genus level on the basis of its 16S rRNA gene sequence and then grouped into distinct clusters on the basis of AFLP polymorphisms. The first step of direct amplification is highly sensitive and has immediate practical consequences, offering fish farmers a rapid diagnosis, while the AFLP is more specific and detects intraspecific variation which, in our study, also reflected geographic correspondence. Because of its superior discriminative properties, AFLP can be an important tool for epidemiological and taxonomic studies of this highly homogeneous genus.

The Thermodynamic Properties of Cubanite

NASA Technical Reports Server (NTRS)

Berger, E. L.; Lauretta, D. S.; Keller, L. P.

2012-01-01

CuFe2S3 exists in two polymorphs, a low-temperature orthorhombic form (cubanite) and a high-temperature cubic form (isocubanite). Cubanite has been identified in the CI-chondrite and Stardust collections. However, the thermodynamic properties of cubanite have neither been measured nor estimated. Our derivation of a thermodynamic model for cubanite allows constraints to be placed on the formation conditions. This data, along with the temperature constraint afforded by the crystal structure, can be used to assess the environments in which cubanite formation is (or is not) thermodynamically favored.

Polymorphism and mesomorphism of oligomeric surfactants: effect of the degree of oligomerization.

PubMed

Jurašin, D; Pustak, A; Habuš, I; Šmit, I; Filipović-Vinceković, N

2011-12-06

A series of cationic oligomeric surfactants (quaternary dodecyldimethylammonium ions with two, three, or four chains connected by an ethylene spacer at the headgroup level, abbreviated as dimer, trimer, and tetramer) were synthesized and characterized. The influence of the degree of oligomerization on their polymorphic and mesomorphic properties was investigated by means of X-ray diffraction, polarizing optical microscopy, thermogravimetry, and differential scanning calorimetry. All compounds display layered arrangements with interdigitated dodecyl chains. The increase in the degree of oligomerization increases the interlayer distance and decreases the ordering in the solid phase; whereas the dimer sample is fully crystalline with well-developed 3D ordering and the trimer and tetramer crystallize as highly ordered crystal smectic phases. The number of thermal phase transitions and sequence of phases are markedly affected by the number of dodecyl chains. Anhydrous samples exhibit polymorphism and thermotropic mesomorphism of the smectic type, with the exception of the tetramer that displays only transitions at higher temperature associated with decomposition and melting. All hydrated compounds form lyotropic mesophases showing reversible phase transitions upon heating and cooling. The sequence of liquid-crystalline phases for the dimer, typical of concentrated ionic surfactant systems, comprises a hexagonal phase at lower temperatures and a smectic phase at higher temperatures. In contrast, the trimer and tetramer reveal textures of the hexagonal phase. © 2011 American Chemical Society

Spin-liquid polymorphism in a correlated electron system on the threshold of superconductivity.

PubMed

Zaliznyak, Igor; Savici, Andrei T; Lumsden, Mark; Tsvelik, Alexei; Hu, Rongwei; Petrovic, Cedomir

2015-08-18

We report neutron scattering measurements which reveal spin-liquid polymorphism in an "11" iron chalcogenide superconductor. It occurs when a poorly metallic magnetic state of FeTe is tuned toward superconductivity by substitution of a small amount of tellurium with isoelectronic sulfur. We observe a liquid-like magnetic response, which is described by the coexistence of two disordered magnetic phases with different local structures whose relative abundance depends on temperature. One is the ferromagnetic (FM) plaquette phase observed in undoped, nonsuperconducting FeTe, which preserves the C4 symmetry of the underlying square lattice and is favored at high temperatures, whereas the other is the antiferromagnetic plaquette phase with broken C4 symmetry, which emerges with doping and is predominant at low temperatures. These findings suggest the coexistence of and competition between two distinct liquid states, and a liquid-liquid phase transformation between these states, in the electronic spin system of FeTe(1-x)(S,Se)(x). We have thus discovered the remarkable physics of competing spin-liquid polymorphs in a correlated electron system approaching superconductivity. Our results facilitate an understanding of large swaths of recent experimental data in unconventional superconductors. In particular, the phase with lower C2 local symmetry, whose emergence precedes superconductivity, naturally accounts for a propensity for forming electronic nematic states which have been observed experimentally, in cuprate and iron-based superconductors alike.

Spin-liquid polymorphism in a correlated electron system on the threshold of superconductivity

PubMed Central

Zaliznyak, Igor; Savici, Andrei T.; Lumsden, Mark; Tsvelik, Alexei; Hu, Rongwei; Petrovic, Cedomir

2015-01-01

We report neutron scattering measurements which reveal spin-liquid polymorphism in an “11” iron chalcogenide superconductor. It occurs when a poorly metallic magnetic state of FeTe is tuned toward superconductivity by substitution of a small amount of tellurium with isoelectronic sulfur. We observe a liquid-like magnetic response, which is described by the coexistence of two disordered magnetic phases with different local structures whose relative abundance depends on temperature. One is the ferromagnetic (FM) plaquette phase observed in undoped, nonsuperconducting FeTe, which preserves the C4 symmetry of the underlying square lattice and is favored at high temperatures, whereas the other is the antiferromagnetic plaquette phase with broken C4 symmetry, which emerges with doping and is predominant at low temperatures. These findings suggest the coexistence of and competition between two distinct liquid states, and a liquid–liquid phase transformation between these states, in the electronic spin system of FeTe1−x(S,Se)x. We have thus discovered the remarkable physics of competing spin-liquid polymorphs in a correlated electron system approaching superconductivity. Our results facilitate an understanding of large swaths of recent experimental data in unconventional superconductors. In particular, the phase with lower C2 local symmetry, whose emergence precedes superconductivity, naturally accounts for a propensity for forming electronic nematic states which have been observed experimentally, in cuprate and iron-based superconductors alike. PMID:26240327

Influence of climate on the presence of colour polymorphism in two montane reptile species

PubMed Central

Broennimann, Olivier; Ursenbacher, Sylvain; Meyer, Andreas; Golay, Philippe; Monney, Jean-Claude; Schmocker, Hans; Guisan, Antoine; Dubey, Sylvain

2014-01-01

The coloration of ectotherms plays an important role in thermoregulation processes. Dark individuals should heat up faster and be able to reach a higher body temperature than light individuals and should therefore have benefits in cool areas. In central Europe, montane local populations of adder (Vipera berus) and asp viper (Vipera aspis) exhibit a varying proportion of melanistic individuals. We tested whether the presence of melanistic V. aspis and V. berus could be explained by climatic conditions. We measured the climatic niche position and breadth of monomorphic (including strictly patterned individuals) and polymorphic local populations, calculated their niche overlap and tested for niche equivalency and similarity. In accordance with expectations, niche overlap between polymorphic local populations of both species is high, and even higher than that of polymorphic versus monomorphic montane local populations of V. aspis, suggesting a predominant role of melanism in determining the niche of ectothermic vertebrates. However, unexpectedly, the niche of polymorphic local populations of both species is narrower than that of monomorphic ones, indicating that colour polymorphism does not always enable the exploitation of a greater variability of resources, at least at the intraspecific level. Overall, our results suggest that melanism might be present only when the thermoregulatory benefit is higher than the cost of predation. PMID:25392313

The effect of colour polymorphism on thermoregulation in an orb web spider.

PubMed

Rao, Dinesh; Mendoza-Cuenca, Luis

2016-08-01

Spiders that build aerial webs in open areas face the risk of overheating due to incident solar radiation. These spiders can counteract overheating by either moving the web to another site or by adopting behavioural thermoregulation within the web. Since moving can be costly, studies have suggested that a passive but effective method of reducing heat load is by light reflectance through body colouration. We explored the interaction between colour and thermoregulation in a colour polymorphic species, under both field and laboratory conditions. We show that in natural conditions, the spiders maintain their body temperature below that of the ambient, but with no difference in surface temperature between colour morphs. In laboratory experiments with internal temperature measurements, white morphs bore the risk of overheating better than the yellow morphs since they heated up slower and cooled faster. We suggest that the thermoregulatory properties of colour polymorphism in Verrucosa arenata have physiological consequences and may play an important role in the maintenance of colour polymorphism in this species.

The effect of colour polymorphism on thermoregulation in an orb web spider

NASA Astrophysics Data System (ADS)

Rao, Dinesh; Mendoza-Cuenca, Luis

2016-08-01

Spiders that build aerial webs in open areas face the risk of overheating due to incident solar radiation. These spiders can counteract overheating by either moving the web to another site or by adopting behavioural thermoregulation within the web. Since moving can be costly, studies have suggested that a passive but effective method of reducing heat load is by light reflectance through body colouration. We explored the interaction between colour and thermoregulation in a colour polymorphic species, under both field and laboratory conditions. We show that in natural conditions, the spiders maintain their body temperature below that of the ambient, but with no difference in surface temperature between colour morphs. In laboratory experiments with internal temperature measurements, white morphs bore the risk of overheating better than the yellow morphs since they heated up slower and cooled faster. We suggest that the thermoregulatory properties of colour polymorphism in Verrucosa arenata have physiological consequences and may play an important role in the maintenance of colour polymorphism in this species.

Application of temperature-gradient gel electrophoresis for detection of prion protein gene polymorphisms in Polish Swiniarka sheep.

PubMed

Jasik, Agnieszka; Reichert, Michal

2006-05-01

This study presents preliminary data on the polymorphism in the prion protein gene of Swiniarka sheep using temperature gradient gel electrophoresis (TGGE). Available data indicate that sensitivity to scrapie is associated with polymorphisms in three codons of prion protein gene: 136,154, and 171. The TGGE method was used to detect point mutations in these codons responsible for sensitivity or resistance to scrapie. This study revealed presence of an allele encoding valine (V) in codon 136, which is associated with high sensitivity to scrapie and occurred in the form of heterozygous allele together with alanine (AV). The highest variability was observed in codon 171, with presence of arginine (R) and glutamine (Q) in the homozygous (RR or QQ) as well as the heterozygous form (RQ). The results of examination of fifty sheep DNA samples with mutations in codons 136, 154, and 171 demonstrated that TGGE can be used as a simple and rapid method to detect mutations in the PrP gene of sheep. Several samples can be run at the same time, making TGGE ideal for the screening of large numbers of samples.

Sputtering Deposition of Sandwich-Structured V2O5/Metal (V, W)/V2O5 Multilayers for the Preparation of High-Performance Thermally Sensitive VO2 Thin Films with Selectivity of VO2 (B) and VO2 (M) Polymorph.

PubMed

Liu, Hengwu; Wan, Dongyun; Ishaq, Ahmad; Chen, Lanli; Guo, Beibei; Shi, Siqi; Luo, Hongjie; Gao, Yanfeng

2016-03-01

For specific application to an uncooled infrared detector, VO2 thin films should have a series of characteristics including purposefully chosen polymorphs, accurate stoichiometry, phase stabilization, a high temperature-coefficient of resistance (TCR), and suitable square-resistance. This work reports controllable preparation of high-performance VO2 films via post annealing of a sandwich-structured V2O5/metal (V, W)/V2O5 multilayer precursor, which was deposited by RF magnetron sputtering. This sandwich structure can dynamically regulate oxygen contents and doping element levels in the films, enabling us to achieve accurate regulation of stoichiometry and polymorphs. The precursor films undergo a B to M phase transition depending on the quantity of the metal layers. At the thickness of the metal layer below a limitation, the resulting film after heat treatment was VO2 (B), and above the limitation, the product was VO2 (M). The optical modulation of the VO2 (M) in the near-infrared region can be tuned from 1.2 to 39.8% (ΔT2000 nm). TCR values can range from -1.89 to -4.29%/K and the square-resistances at room temperature (R0) from 69.68 to 12.63 kΩ. The simplicity in phase regulation of the present method and the superior optical and electrical properties of the films may allow its wide applications in thermo-opto-electro sensing devices.

The anomalously high melting temperature of bilayer ice.

PubMed

Kastelowitz, Noah; Johnston, Jessica C; Molinero, Valeria

2010-03-28

Confinement of water usually depresses its melting temperature. Here we use molecular dynamics simulations to determine the liquid-crystal equilibrium temperature for water confined between parallel hydrophobic or mildly hydrophilic plates as a function of the distance between the surfaces. We find that bilayer ice, an ice polymorph in which the local environment of each water molecule strongly departs from the most stable tetrahedral structure, has the highest melting temperature (T(m)) of the series of l-layer ices. The melting temperature of bilayer ice is not only unusually high compared to the other confined ices, but also above the melting point of bulk hexagonal ice. Recent force microscopy experiments of water confined between graphite and a tungsten tip reveal the formation of ice at room temperature [K. B. Jinesh and J. W. M. Frenken, Phys. Rev. Lett. 101, 036101 (2008)]. Our results suggest that bilayer ice, for which we compute a T(m) as high as 310 K in hydrophobic confinement, is the crystal formed in those experiments.

Thermal, spectroscopic and structural characterization of isostructural phase transition in 4-hydroxybenzaldehyde

NASA Astrophysics Data System (ADS)

Panicker, Lata

2018-05-01

Polycrystalline samples of 4-hydroxybenzaldehyde (4-HOBAL) were investigated using differential scanning calorimeter (DSC), Raman spectroscopy and X-ray powder diffraction. The DSC data indicated that 4-HOBAL on heating undergoes a polymorphic transformation from polymorph I to polymorph II. The polymorph II formed remains metastable at ambient condition and transforms to polymorph I when annealed at ambient temperature for more than seven days. The structural information of polymorphs I and II obtained using its X-ray powder diffraction patterns indicated that 4-HOBAL undergoes an isostructural phase transition from polymorph I (monoclinic, P21/c) to polymorph II (monoclinic, P21/c). Raman data suggest that this structural change is associated with some change in its molecular interactions. Thus, in 4-HOBAL the polymorphic phase transformation (II to I) even though energetically favoured is kinetically hindered.

Effect of ethanol on crystallization of the polymorphs of L-histidine

NASA Astrophysics Data System (ADS)

Wantha, Lek; Punmalee, Neeranuch; Sawaddiphol, Vanida; Flood, Adrian E.

2018-05-01

It is known that the antisolvents used for crystallization can affect the crystallization outcome and may promote the crystallization of a specific polymorph. In this study L-histidine (L-his) is used as a model substance, and ethanol was selected to be an antisolvent. The formation of the polymorphs of L-his in antisolvent crystallization as a function of supersaturation, ethanol volume fraction, and temperature was studied. The induction time for the antisolvent crystallization was also measured. The results showed that the induction time decreases with higher supersaturation and ethanol volume fraction, indicating that the nucleation rate of L-his from antisolvent crystallization (where water was used as the solvent and ethanol as the antisolvent) increases with higher supersaturation, as expected, and ethanol fraction. At all temperatures studied, the pure metastable polymorph B of L-his was obtained initially at higher ethanol volume fraction and supersaturation, while a mixture of the polymorphs A and B was obtained at lower ethanol volume fraction and supersaturation.

Crystallization of D-mannitol in binary mixtures with NaCl: phase diagram and polymorphism.

PubMed

Telang, Chitra; Suryanarayanan, Raj; Yu, Lian

2003-12-01

To study the crystallization, polymorphism, and phase behavior of D-mannitol in binary mixtures with NaCl to better understand their interactions in frozen aqueous solutions. Differential scanning calorimetry, hot-stage microscopy, Raman microscopy, and variable-temperature X-ray diffractometry were used to characterize D-mannitol-NaCl mixtures. NaCl and D-mannitol exhibited significant melt miscibility (up to 7.5% w/w or 0.20 mole fraction of NaCl) and a eutectic phase diagram (eutectic composition 7.5% w/w NaCl; eutectic temperature 150 degrees C for the alpha and beta polymorphs of D-mannitol and 139 degrees C for the delta). The presence of NaCl did not prevent mannitol from crystallizing but, depending on sample size, affected the polymorph crystallized: below 10 mg, delta was obtained; above 100 mg, alpha was obtained. Pure mannitol crystallized under the same conditions first as the delta polymorph and then as the a polymorph, with the latter nucleating on the former. KCl showed similar eutectic points and melt miscibility with D-mannitol as NaCl. LiCl yielded lower eutectic melting points, inhibited the crystallization of D-mannitol during cooling, and enabled the observation of its glass transition. Despite their structural dissimilarity, significant melt miscibility exists between D-mannitol and NaCl. Their phase diagram has been determined and features polymorph-dependent eutectic points. NaCl influences the polymorphic behavior of mannitol, and the effect is linked to the crystallization of mannitol in two polymorphic stages.

Markers and mapping revisited: finding your gene.

PubMed

Jones, Neil; Ougham, Helen; Thomas, Howard; Pasakinskiene, Izolda

2009-01-01

This paper is an update of our earlier review (Jones et al., 1997, Markers and mapping: we are all geneticists now. New Phytologist 137: 165-177), which dealt with the genetics of mapping, in terms of recombination as the basis of the procedure, and covered some of the first generation of markers, including restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNA (RAPDs), simple sequence repeats (SSRs) and quantitative trait loci (QTLs). In the intervening decade there have been numerous developments in marker science with many new systems becoming available, which are herein described: cleavage amplification polymorphism (CAP), sequence-specific amplification polymorphism (S-SAP), inter-simple sequence repeat (ISSR), sequence tagged site (STS), sequence characterized amplification region (SCAR), selective amplification of microsatellite polymorphic loci (SAMPL), single nucleotide polymorphism (SNP), expressed sequence tag (EST), sequence-related amplified polymorphism (SRAP), target region amplification polymorphism (TRAP), microarrays, diversity arrays technology (DArT), single-strand conformation polymorphism (SSCP), denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE) and methylation-sensitive PCR. In addition there has been an explosion of knowledge and databases in the area of genomics and bioinformatics. The number of flowering plant ESTs is c. 19 million and counting, with all the opportunity that this provides for gene-hunting, while the survey of bioinformatics and computer resources points to a rapid growth point for future activities in unravelling and applying the burst of new information on plant genomes. A case study is presented on tracking down a specific gene (stay-green (SGR), a post-transcriptional senescence regulator) using the full suite of mapping tools and comparative mapping resources. We end with a brief speculation on how genome analysis may progress into the future of this highly dynamic arena of plant science.

The impact of Ti and temperature on the stability of Nb5Si3 phases: a first-principles study

PubMed Central

Papadimitriou, Ioannis; Utton, Claire; Tsakiropoulos, Panos

2017-01-01

Abstract Nb-silicide based alloys could be used at T > 1423 K in future aero-engines. Titanium is an important additive to these new alloys where it improves oxidation, fracture toughness and reduces density. The microstructures of the new alloys consist of an Nb solid solution, and silicides and other intermetallics can be present. Three Nb5Si3 polymorphs are known, namely αNb5Si3 (tI32 Cr5B3-type, D8l), βNb5Si3 (tI32 W5Si3-type, D8m) and γNb5Si3 (hP16 Mn5Si3-type, D88). In these 5–3 silicides Nb atoms can be substituted by Ti atoms. The type of stable Nb5Si3 depends on temperature and concentration of Ti addition and is important for the stability and properties of the alloys. The effect of increasing concentration of Ti on the transition temperature between the polymorphs has not been studied. In this work first-principles calculations were used to predict the stability and physical properties of the various Nb5Si3 silicides alloyed with Ti. Temperature-dependent enthalpies of formation were computed, and the transition temperature between the low (α) and high (β) temperature polymorphs of Nb5Si3 was found to decrease significantly with increasing Ti content. The γNb5Si3 was found to be stable only at high Ti concentrations, above approximately 50 at. % Ti. Calculation of physical properties and the Cauchy pressures, Pugh’s index of ductility and Poisson ratio showed that as the Ti content increased, the bulk moduli of all silicides decreased, while the shear and elastic moduli and the Debye temperature increased for the αNb5Si3 and γNb5Si3 and decreased for βNb5Si3. With the addition of Ti the αNb5Si3 and γNb5Si3 became less ductile, whereas the βNb5Si3 became more ductile. When Ti was added in the αNb5Si3 and βNb5Si3 the linear thermal expansion coefficients of the silicides decreased, but the anisotropy of coefficient of thermal expansion did not change significantly. PMID:28740563

Structural properties of hydrolyzed high-amylose rice starch by α-amylase from Bacillus licheniformis.

PubMed

Qin, Fengling; Man, Jianmin; Xu, Bin; Hu, Maozhi; Gu, Minghong; Liu, Qiaoquan; Wei, Cunxu

2011-12-14

High-amylose cereal starch has a great benefit on human health through its resistant starch (RS) content. Enzyme hydrolysis of native starch is very helpful in understanding the structure of starch granules and utilizing them. In this paper, native starch granules were isolated from a transgenic rice line (TRS) enriched with amylose and RS and hydrolyzed by α-amylase. Structural properties of hydrolyzed TRS starches were studied by X-ray powder diffraction, Fourier transform infrared, and differential scanning calorimetry. The A-type polymorph of TRS C-type starch was hydrolyzed faster than the B-type polymorph, but the crystallinity did not significantly change during enzyme hydrolysis. The degree of order in the external region of starch granule increased with increasing enzyme hydrolysis time. The amylose content decreased at first and then went back up during enzyme hydrolysis. The hydrolyzed starches exhibited increased onset and peak gelatinization temperatures and decreased gelatinization enthalpy on hydrolysis. These results suggested that the B-type polymorph and high amylose that formed the double helices and amylose-lipid complex increased the resistance to BAA hydrolysis. Furthermore, the spectrum results of RS from TRS native starch digested by pancreatic α-amylase and amyloglucosidase also supported the above conclusion.

Polymorphism, mesomorphism, and metastability of monoelaidin in excess water.

PubMed

Chung, H; Caffrey, M

1995-11-01

The polymorphic and metastable phase behavior of monoelaidin dry and in excess water was studied by using high-sensitivity differential scanning calorimetry and time-resolved x-ray diffraction in the temperature range of 4 degrees C to 60 degrees C. To overcome problems associated with a pronounced thermal history-dependent phase behavior, simultaneous calorimetry and time-resolved x-ray diffraction measurements were performed on individual samples. Monoelaidin/water samples were prepared at room temperature and stored at 4 degrees C for up to 1 week before measurement. The initial heating scan from 4 degrees C to 60 degrees C showed complex phase behavior with the sample in the lamellar crystalline (Lc0) and cubic (Im3m, Q229) phases at low and high temperatures, respectively. The Lc0 phase transforms to the lamellar liquid crystalline (L alpha) phase at 38 degrees C. At 45 degrees C, multiple unresolved lines appeared that coexisted with those from the L alpha phase in the low-angle region of the diffraction pattern that have been assigned previously to the so-called X phase (Caffrey, 1987, 1989). With further heating the X phase converts to the Im3m cubic phase. Regardless of previous thermal history, cooling calorimetric scans revealed a single exotherm at 22 degrees C, which was assigned to an L alpha+cubic (Im3m, Q229)-to-lamellar gel (L beta) phase transition. The response of the sample to a cooling followed by a reheating or isothermal protocol depended on the length of time the sample was incubated at 4 degrees C. A model is proposed that reconciles the complex polymorphic, mesomorphic, and metastability interrelationships observed with this lipid/water system. Dry monoelaidin exists in the lamellar crystalline (beta) phase in the 4 degrees C to 45 degrees C range. The beta phase transforms to a second lamellar crystalline polymorph identified as beta* at 45 degrees C that subsequently melts at 57 degrees C. The beta phase observed with dry monoelaidin is identical to the LcO phase formed by monoelaidin that was dispersed in excess water and that had not been previously heated.

Polymorphism, mesomorphism, and metastability of monoelaidin in excess water.

PubMed Central

Chung, H; Caffrey, M

1995-01-01

The polymorphic and metastable phase behavior of monoelaidin dry and in excess water was studied by using high-sensitivity differential scanning calorimetry and time-resolved x-ray diffraction in the temperature range of 4 degrees C to 60 degrees C. To overcome problems associated with a pronounced thermal history-dependent phase behavior, simultaneous calorimetry and time-resolved x-ray diffraction measurements were performed on individual samples. Monoelaidin/water samples were prepared at room temperature and stored at 4 degrees C for up to 1 week before measurement. The initial heating scan from 4 degrees C to 60 degrees C showed complex phase behavior with the sample in the lamellar crystalline (Lc0) and cubic (Im3m, Q229) phases at low and high temperatures, respectively. The Lc0 phase transforms to the lamellar liquid crystalline (L alpha) phase at 38 degrees C. At 45 degrees C, multiple unresolved lines appeared that coexisted with those from the L alpha phase in the low-angle region of the diffraction pattern that have been assigned previously to the so-called X phase (Caffrey, 1987, 1989). With further heating the X phase converts to the Im3m cubic phase. Regardless of previous thermal history, cooling calorimetric scans revealed a single exotherm at 22 degrees C, which was assigned to an L alpha+cubic (Im3m, Q229)-to-lamellar gel (L beta) phase transition. The response of the sample to a cooling followed by a reheating or isothermal protocol depended on the length of time the sample was incubated at 4 degrees C. A model is proposed that reconciles the complex polymorphic, mesomorphic, and metastability interrelationships observed with this lipid/water system. Dry monoelaidin exists in the lamellar crystalline (beta) phase in the 4 degrees C to 45 degrees C range. The beta phase transforms to a second lamellar crystalline polymorph identified as beta* at 45 degrees C that subsequently melts at 57 degrees C. The beta phase observed with dry monoelaidin is identical to the LcO phase formed by monoelaidin that was dispersed in excess water and that had not been previously heated. Images FIGURE 3 PMID:8580338

High-pressure, high-temperature Raman spectroscopy of Ca 2GeO 4 (olivine form): some insights on anharmonicity

NASA Astrophysics Data System (ADS)

Gillet, Philippe; Guyot, Francois; Malezieux, Jean-Marie

1989-12-01

High pressure (up to 2.7 GPa) and high temperature (up to 1000 K) Raman spectra of Ca 2GeO 4 (olivine form) have been recorded. Measurements of the pressure- and temperature-induced frequency shifts of 14 modes have been performed. The classical mode Gruneisen parameter and a corresponding parameter related to temperature variation are calculated. For the high frequency modes (GeO stretching) we calculate these parameters with local tetrahedral elastic parameters. From these parameters anharmonic parameters are calculated for each Raman active mode. The effect of anharmonicity on the specific heat is calculated and compared with calorimetric data. Taking anharmonicity into account leads to a departure from the Dulong and Petit limit of the order of 2% at 1000 K and more than 6% at 2000 K, in good accord with experimental data. We propose that, eventually, such effects might be significant in the calculations of thermodynamic properties of mantle silicates like forsterite and its polymorphs.

Coarse-grained modeling of crystal growth and polymorphism of a model pharmaceutical molecule.

PubMed

Mandal, Taraknath; Marson, Ryan L; Larson, Ronald G

2016-10-04

We describe a systematic coarse-graining method to study crystallization and predict possible polymorphs of small organic molecules. In this method, a coarse-grained (CG) force field is obtained by inverse-Boltzmann iteration from the radial distribution function of atomistic simulations of the known crystal. With the force field obtained by this method, we show that CG simulations of the drug phenytoin predict growth of a crystalline slab from a melt of phenytoin, allowing determination of the fastest-growing surface, as well as giving the correct lattice parameters and crystal morphology. By applying meta-dynamics to the coarse-grained model, a new crystalline form of phenytoin (monoclinic, space group P2 1 ) was predicted which is different from the experimentally known crystal structure (orthorhombic, space group Pna2 1 ). Atomistic simulations and quantum calculations then showed the polymorph to be meta-stable at ambient temperature and pressure, and thermodynamically more stable than the conventional orthorhombic crystal at high pressure. The results suggest an efficient route to study crystal growth of small organic molecules that could also be useful for identification of possible polymorphs as well.

Melting analysis on microbeads in rapid temperature-gradient inside microchannels for single nucleotide polymorphisms detectiona)

PubMed Central

Li, Kan-Chien; Ding, Shih-Torng; Lin, En-Chung; Wang, Lon (Alex); Lu, Yen-Wen

2014-01-01

A continuous-flow microchip with a temperature gradient in microchannels was utilized to demonstrate spatial melting analysis on microbeads for clinical Single Nucleotide Polymorphisms (SNPs) genotyping on animal genomic DNA. The chip had embedded heaters and thermometers, which created a rapid and yet stable temperature gradient between 60 °C and 85 °C in a short distance as the detection region. The microbeads, which served as mobile supports carrying the target DNA and fluorescent dye, were transported across the temperature gradient. As the surrounding temperature increased, the fluorescence signals of the microbeads decayed with this relationship being acquired as the melting curve. Fast DNA denaturation, as a result of the improved heat transfer and thermal stability due to scaling, was also confirmed. Further, each individual microbead could potentially bear different sequences and pass through the detection region, one by one, for a series of melting analysis, with multiplex, high-throughput capability being possible. A prototype was tested with target DNA samples in different genotypes (i.e., wild and mutant types) with a SNP location from Landrace sows. The melting temperatures were obtained and compared to the ones using a traditional tube-based approach. The results showed similar levels of SNP discrimination, validating our proposed technique for scanning homozygotes and heterozygotes to distinguish single base changes for disease research, drug development, medical diagnostics, agriculture, and animal production. PMID:25553186

Influence of climate on the presence of colour polymorphism in two montane reptile species.

PubMed

Broennimann, Olivier; Ursenbacher, Sylvain; Meyer, Andreas; Golay, Philippe; Monney, Jean-Claude; Schmocker, Hans; Guisan, Antoine; Dubey, Sylvain

2014-11-01

The coloration of ectotherms plays an important role in thermoregulation processes. Dark individuals should heat up faster and be able to reach a higher body temperature than light individuals and should therefore have benefits in cool areas. In central Europe, montane local populations of adder (Vipera berus) and asp viper (Vipera aspis) exhibit a varying proportion of melanistic individuals. We tested whether the presence of melanistic V. aspis and V. berus could be explained by climatic conditions. We measured the climatic niche position and breadth of monomorphic (including strictly patterned individuals) and polymorphic local populations, calculated their niche overlap and tested for niche equivalency and similarity. In accordance with expectations, niche overlap between polymorphic local populations of both species is high, and even higher than that of polymorphic versus monomorphic montane local populations of V. aspis, suggesting a predominant role of melanism in determining the niche of ectothermic vertebrates. However, unexpectedly, the niche of polymorphic local populations of both species is narrower than that of monomorphic ones, indicating that colour polymorphism does not always enable the exploitation of a greater variability of resources, at least at the intraspecific level. Overall, our results suggest that melanism might be present only when the thermoregulatory benefit is higher than the cost of predation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

[Thermodynamics of drug polymorphism: domains and stability hierarchy by pressure temperature diagram. Application to the tetramorphism of fananserine].

PubMed

Toscani, S

2002-05-01

In this communication, an application of classical thermodynamics to crystalline solid state polymorphism is shown to allow stability p, T domains and stability hierarchy among crystalline phases of a polymorph to be defined by constructing the unary p, T phase diagram. The three topological rules upon which this construction is founded are presented; the first one is a straight consequence of the least vapour pressure criterion by Ostwald. Calculation of triple point co-ordinates and of two-phase equilibrium curves is based upon using both thermodynamic and crystallographic data obtained at ordinary pressure. Clapeyron equation allows the slopes of the straight lines representing equilibria between condensed phases to be calculated and, hence, triple points situated at high or negative pressure to be determined. On the other hand, the hierarchy among the thermodynamic stability degrees of the crystalline varieties may be inferred from the location of the sublimation curves, by merely acknowledging inequalities among vapour pressures at each temperature on the whole T-range. These building-up processes are pointed out by outlining the achievement of a phase diagram related to the tetramorphism of fananserine, an anxiolytic drug. Three out four crystalline forms, namely phases II, III and IV, possess their own stability domain, although those belonging to phases II and III are limited at high pressure by that of phase IV. Conversely, phase I is overall metastable and exhibits a whole monotropic behaviour.

Polymorphism control of superconductivity and magnetism in Cs(3)C(60) close to the Mott transition.

PubMed

Ganin, Alexey Y; Takabayashi, Yasuhiro; Jeglic, Peter; Arcon, Denis; Potocnik, Anton; Baker, Peter J; Ohishi, Yasuo; McDonald, Martin T; Tzirakis, Manolis D; McLennan, Alec; Darling, George R; Takata, Masaki; Rosseinsky, Matthew J; Prassides, Kosmas

2010-07-08

The crystal structure of a solid controls the interactions between the electronically active units and thus its electronic properties. In the high-temperature superconducting copper oxides, only one spatial arrangement of the electronically active Cu(2+) units-a two-dimensional square lattice-is available to study the competition between the cooperative electronic states of magnetic order and superconductivity. Crystals of the spherical molecular C(60)(3-) anion support both superconductivity and magnetism but can consist of fundamentally distinct three-dimensional arrangements of the anions. Superconductivity in the A(3)C(60) (A = alkali metal) fullerides has been exclusively associated with face-centred cubic (f.c.c.) packing of C(60)(3-) (refs 2, 3), but recently the most expanded (and thus having the highest superconducting transition temperature, T(c); ref. 4) composition Cs(3)C(60) has been isolated as a body-centred cubic (b.c.c.) packing, which supports both superconductivity and magnetic order. Here we isolate the f.c.c. polymorph of Cs(3)C(60) to show how the spatial arrangement of the electronically active units controls the competing superconducting and magnetic electronic ground states. Unlike all the other f.c.c. A(3)C(60) fullerides, f.c.c. Cs(3)C(60) is not a superconductor but a magnetic insulator at ambient pressure, and becomes superconducting under pressure. The magnetic ordering occurs at an order of magnitude lower temperature in the geometrically frustrated f.c.c. polymorph (Néel temperature T(N) = 2.2 K) than in the b.c.c.-based packing (T(N) = 46 K). The different lattice packings of C(60)(3-) change T(c) from 38 K in b.c.c. Cs(3)C(60) to 35 K in f.c.c. Cs(3)C(60) (the highest found in the f.c.c. A(3)C(60) family). The existence of two superconducting packings of the same electronically active unit reveals that T(c) scales universally in a structure-independent dome-like relationship with proximity to the Mott metal-insulator transition, which is governed by the role of electron correlations characteristic of high-temperature superconducting materials other than fullerides.

Spin liquid polymorphism in a correlated electron system on the threshold of superconductivity

DOE PAGES

Zalinznyak, Igor; Savici, Andrei T.; Lumsden, Mark D.; ...

2015-08-18

We report neutron scattering measurements which reveal spin-liquid polymorphism in an “11” iron chalcogenide superconductor. It occurs when a poorly metallic magnetic state of FeTe is tuned toward superconductivity by substitution of a small amount of tellurium with isoelectronic sulfur. We also observe a liquid-like magnetic response, which is described by the coexistence of two disordered magnetic phases with different local structures whose relative abundance depends on temperature. One is the ferromagnetic (FM) plaquette phase observed in undoped, nonsuperconducting FeTe, which preserves the C 4 symmetry of the underlying square lattice and is favored at high temperatures, whereas the othermore » is the antiferromagnetic plaquette phase with broken C 4 symmetry, which emerges with doping and is predominant at low temperatures. These findings suggest the coexistence of and competition between two distinct liquid states, and a liquid–liquid phase transformation between these states, in the electronic spin system of FeTe 1-x(S,Se) x. We have thus discovered the remarkable physics of competing spin-liquid polymorphs in a correlated electron system approaching superconductivity. These results facilitate an understanding of large swaths of recent experimental data in unconventional superconductors. In particular, the phase with lower C 2 local symmetry, whose emergence precedes superconductivity, naturally accounts for a propensity for forming electronic nematic states which have been observed experimentally, in cuprate and iron-based superconductors alike.« less

Photochemical solution processing of films of metastable phases for flexible devices: the β-Bi2O3 polymorph

PubMed Central

Pérez-Mezcua, Dulce; Bretos, Iñigo; Jiménez, Ricardo; Ricote, Jesús; Jiménez-Rioboó, Rafael J.; da Silva, Cosmelina Gonçalves; Chateigner, Daniel; Fuentes-Cobas, Luis; Sirera, Rafael; Calzada, M. Lourdes

2016-01-01

The potential of UV-light for the photochemical synthesis and stabilization of non-equilibrium crystalline phases in thin films is demonstrated for the β-Bi2O3 polymorph. The pure β-Bi2O3 phase is thermodynamically stable at high temperature (450–667 °C), which limits its applications in devices. Here, a tailored UV-absorbing bismuth(III)-N-methyldiethanolamine complex is selected as an ideal precursor for this phase, in order to induce under UV-light the formation of a –Bi–O–Bi– continuous network in the deposited layers and the further conversion into the β-Bi2O3 polymorph at a temperature as low as 250 °C. The stabilization of the β-Bi2O3 films is confirmed by their conductivity behavior and a thorough characterization of their crystal structure. This is also supported by their remarkable photocatalytic activity. Besides, this processing method has allowed us for the first time the preparation of β-Bi2O3 films on flexible plastic substrates, which opens new opportunities for using these materials in potential applications not available until now (e.g., flexible photocatalytic reactors, self-cleaning surfaces or wearable antimicrobial fabrics). Therefore, photochemical solution deposition (PCSD) demonstrates to be not only an efficient approach for the low temperature processing of oxide films, but also an excellent alternative for the stabilization of metastable phases. PMID:27996042

Polymorphic one-dimensional (N2H4)2ZnTe: soluble precursors for the formation of hexagonal or cubic zinc telluride.

PubMed

Mitzi, David B

2005-10-03

Two hydrazine zinc(II) telluride polymorphs, (N2H4)2ZnTe, have been isolated, using ambient-temperature solution-based techniques, and the crystal structures determined: alpha-(N2H4)2ZnTe (1) [P21, a = 7.2157(4) Angstroms, b = 11.5439(6) Angstroms, c = 7.3909(4) Angstroms, beta = 101.296(1) degrees, Z = 4] and beta-(N2H4)2ZnTe (2) [Pn, a = 8.1301(5) Angstroms, b = 6.9580(5) Angstroms, c = 10.7380(7) Angstroms, beta = 91.703(1) degrees, Z = 4]. The zinc atoms in 1 and 2 are tetrahedrally bonded to two terminal hydrazine molecules and two bridging tellurium atoms, leading to the formation of extended one-dimensional (1-D) zinc telluride chains, with different chain conformations and packings distinguishing the two polymorphs. Thermal decomposition of (N2H4)2ZnTe first yields crystalline wurtzite (hexagonal) ZnTe at temperatures as low as 200 degrees C, followed by the more stable zinc blende (cubic) form at temperatures above 350 degrees C. The 1-D polymorphs are soluble in hydrazine and can be used as convenient precursors for the low-temperature solution processing of p-type ZnTe semiconducting films.

Rayleigh analysis of domain dynamics across temperature induced polymorphic phase transitions in lead-free piezoceramics (1‑x)(BaTi0.88Sn0.12)–x(Ba0.7Ca0.3)TiO3

NASA Astrophysics Data System (ADS)

Abebe, Mulualem; Brajesh, Kumar; Singh Malhotra, Jaskaran; Ranjan, Rajeev

2018-05-01

We carried out a Rayleigh analysis of the dielectric permittivity of a lead-free piezoceramic system (1‑x)(BaTi0.88Sn0.12)–x(Ba0.7Ca0.3)TiO3 across the composition and temperature induced polymorphic phase transformations to determine the trend in the reversible and irreversible domain wall motion across the composition and temperature induced structural changes. Experiments were carried out on three representative compositions x  =  0.10, 0.2, and 0.25 exhibiting rhombohedral, orthorhombic, and tetragonal phases at room temperature. While confirming that the irreversible Rayleigh parameter is large in the orthorhombic phase, we discuss a correspondence between the reduction in the coercive field and the corresponding increase in the irreversible Rayleigh parameter. We also show how the proximity of the Curie point to the polymorphic phase boundary greatly undermines this correspondence.

Supercritical fluids crystallization of budesonide and flunisolide.

PubMed

Velaga, Sitaram P; Berger, Rolf; Carlfors, Johan

2002-10-01

Budesonide and flunisolide anhydrate were crystallized using the solution enhanced dispersion by supercritical fluids (SEDS) technique. The aim was to investigate the possibility of preparing different pure polymorphs. 0.25% w/v solutions of each drug were prepared from acetone and methanol. Operating conditions were 40-80 degrees C and 80-200 bars. The flow rate of drug solution was 0.3 mL/min and that of CO2 was 9-25 mL/min. Sample characterizations included differential scanning calorimetry, X-ray powder diffraction, variable temperature X-ray diffraction, scanning electron microscopy, and solubility studies. The particle morphology of budesonide was dependent on the nature of the solvent. SEDS processing of flunisolide with acetone at 100 bars resulted in the formation of polymorphic mixtures at 80 degrees C and a new polymorph III at 60 C and 40 degrees C. With methanol at 100 bars another new polymorph IV was formed with different particle morphology at 80 degrees C and a polymorphic mixture at 60 degrees C. Using the SEDS, microparticles of crystalline budesonide were prepared and new polymorphs of flunisolide were produced. Particle characteristics were controlled by the temperature, pressure and relative flow rates of drug solution and CO2.

Solubility and crystal nucleation in organic solvents of two polymorphs of curcumin.

PubMed

Liu, Jin; Svärd, Michael; Hippen, Perschia; Rasmuson, Åke C

2015-07-01

Two crystal polymorphs of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) have been obtained by crystallization from ethanol (EtOH) solution. The polymorphs have been characterized by differential scanning calorimetry, infrared spectroscopy, and X-ray powder diffraction and shown to be the previously described forms I and III. The solubility of both polymorphs in EtOH and of one polymorph in ethyl acetate (EA) has been measured between 10°C and 50°C with a gravimetric method. Primary nucleation of curcumin from EtOH solution has been investigated in 520 constant temperature crystallization experiments in sealed, magnetically stirred vials under different conditions of supersaturation, temperature, and agitation rate. By a thermodynamic analysis of the melting data and solubility of form I, the solid-state activity is estimated from 10°C up to the melting point. The solubility is lower in EtOH than in EA, and in both solvents, a positive deviation from Raoult's law is observed. Form I has lower solubility than form III and is accordingly thermodynamically more stable over the investigated temperature interval. Extrapolation of solubility regression models indicates that there should be a low-temperature enantiotropic transition point, below which form I will be metastable. By slurry conversion experiments, it is established that this temperature is below -30°C. All nucleation experiments resulted in the stable form I. The induction time is observed to decrease with increasing agitation rate up to a certain point, and then increase with further increasing agitation rate; a trend previously observed for other compounds. By correlating the induction time data obtained at different supersaturation and temperature, the interfacial energy of form I in EtOH is estimated to be 3.0 mJ/m(2) . © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

New Insights into the Diverse Electronic Phases of a Novel Vanadium Dioxide Polymorph: A Terahertz Spectroscopy Study

PubMed Central

Lourembam, James; Srivastava, Amar; La-o-vorakiat, Chan; Rotella, H.; Venkatesan, T.; Chia, Elbert E. M.

2015-01-01

A remarkable feature of vanadium dioxide is that it can be synthesized in a number of polymorphs. The conductivity mechanism in the metastable layered polymorph VO2(B) thin films has been investigated by terahertz time-domain spectroscopy (THz-TDS). In VO2(B), a critical temperature of 240 K marks the appearance of a non-zero Drude term in the observed complex conductivity, indicating the evolution from a pure insulating state towards a metallic state. In contrast, the THz conductivity of the well-known VO2(M1) is well fitted only by a modification of the Drude model to include backscattering. We also identified two different THz conductivity regimes separated by temperature in these two polymorphs. The electronic phase diagram is constructed, revealing that the width and onset of the metal-insulator transition in the B phase develop differently from the M1 phase. PMID:25777320

Solid-state properties and crystallization behavior of PHA-739521 polymorphs.

PubMed

Sun, Changquan Calvin

2006-08-17

PHA-739521 is an experimental compound that exhibits polymorphism. The two anhydrous crystal forms, I and II, are characterized using powder X-ray diffractometry, thermal analyses, moisture sorption gravimetry. Both Forms I and II are non-hygroscopic and are stable to compaction pressure. The melting temperature is about 152 degrees C for Form I and 168 degrees C for Form II. Forms I and II are enantiotropically related where Form I is more stable below a transition temperature of approximately 70 degrees C. Crystallization behavior of this compound from solutions and during heating is also studied. Information obtained is used to design an appropriate crystallization process to successfully manufacture desired polymorph at large scale.

Possible significance of cubic water-ice, H2O-Ic, in the atmospheric water cycle of Mars

NASA Technical Reports Server (NTRS)

Gooding, James L.

1988-01-01

The possible formation and potential significance of the cubic ice polymorph on Mars is discussed. When water-ice crystallizes on Earth, the ambient conditions of temperature and pressure result in the formation of the hexagonal ice polymorph; however, on Mars, the much lower termperature and pressures may permit the crystallization of the cubic polymorph. Cubic ice has two properties of possible importance on Mars: it is an excellant nucleator of other volatiles (such as CO2), and it undergoes an exothermic transition to hexagonal ice at temperatures above 170 K. These properties may have significant implications for both martian cloud formation and the development of the seasonal polar caps.

The phase diagram of ammonium nitrate.

PubMed

Chellappa, Raja S; Dattelbaum, Dana M; Velisavljevic, Nenad; Sheffield, Stephen

2012-08-14

The pressure-temperature (P-T) phase diagram of ammonium nitrate (AN) [NH(4)NO(3)] has been determined using synchrotron x-ray diffraction (XRD) and Raman spectroscopy measurements. Phase boundaries were established by characterizing phase transitions to the high temperature polymorphs during multiple P-T measurements using both XRD and Raman spectroscopy measurements. At room temperature, the ambient pressure orthorhombic (Pmmn) AN-IV phase was stable up to 45 GPa and no phase transitions were observed. AN-IV phase was also observed to be stable in a large P-T phase space. The phase boundaries are steep with a small phase stability regime for high temperature phases. A P-V-T equation of state based on a high temperature Birch-Murnaghan formalism was obtained by simultaneously fitting the P-V isotherms at 298, 325, 446, and 467 K, thermal expansion data at 1 bar, and volumes from P-T ramping experiments. Anomalous thermal expansion behavior of AN was observed at high pressure with a modest negative thermal expansion in the 3-11 GPa range for temperatures up to 467 K. The role of vibrational anharmonicity in this anomalous thermal expansion behavior has been established using high P-T Raman spectroscopy.

The phase diagram of ammonium nitrate

NASA Astrophysics Data System (ADS)

Chellappa, Raja S.; Dattelbaum, Dana M.; Velisavljevic, Nenad; Sheffield, Stephen

2012-08-01

The pressure-temperature (P-T) phase diagram of ammonium nitrate (AN) [NH4NO3] has been determined using synchrotron x-ray diffraction (XRD) and Raman spectroscopy measurements. Phase boundaries were established by characterizing phase transitions to the high temperature polymorphs during multiple P-T measurements using both XRD and Raman spectroscopy measurements. At room temperature, the ambient pressure orthorhombic (Pmmn) AN-IV phase was stable up to 45 GPa and no phase transitions were observed. AN-IV phase was also observed to be stable in a large P-T phase space. The phase boundaries are steep with a small phase stability regime for high temperature phases. A P-V-T equation of state based on a high temperature Birch-Murnaghan formalism was obtained by simultaneously fitting the P-V isotherms at 298, 325, 446, and 467 K, thermal expansion data at 1 bar, and volumes from P-T ramping experiments. Anomalous thermal expansion behavior of AN was observed at high pressure with a modest negative thermal expansion in the 3-11 GPa range for temperatures up to 467 K. The role of vibrational anharmonicity in this anomalous thermal expansion behavior has been established using high P-T Raman spectroscopy.

Quantum size effects in the size-temperature phase diagram of gallium: structural characterization of shape-shifting clusters.

PubMed

Steenbergen, Krista G; Gaston, Nicola

2015-02-09

Finite temperature analysis of cluster structures is used to identify signatures of the low-temperature polymorphs of gallium, based on the results of first-principle Born-Oppenheimer molecular dynamics simulations. Pre-melting structural transitions proceed from either the β- and/or the δ-phase to the γ- or δ-phase, with a size- dependent phase progression. We relate the stability of each isomer to the electronic structures of the different phases, giving new insight into the origin of polymorphism in this complicated element. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isothermal Crystallization Kinetics of Palm Oil as Influenced by Addition of a Commercial Phytosterol Ester Mixture.

PubMed

Daels, Eva; Goderis, Bart; Matton, Valerie; Foubert, Imogen

2018-04-18

In literature there is good agreement on the health-promoting effects of phytosterols. However, addition of phytosterol esters (PEs) to lipid (containing food products) may influence its crystallization behavior. This study investigated the crystallization kinetics of palm oil (PO) after addition of PEs in high concentrations (≥10%). The isothermal crystallization of the PE-PO blends was analyzed at a temperature of 20 °C and at a supercooling of 18.7 °C using differential scanning calorimetry and time-resolved synchrotron X-ray diffraction. At increasing PE concentrations, PO crystallization at an isothermal temperature of 20 °C started later and was slower and a smaller amount of crystals were formed. Furthermore, a delay in polymorphic transition from α to β' was observed. When the blends were isothermally crystallized at a supercooling of 18.7 °C, only two of these effects remained: the delay in polymorphic transition and the decrease in crystalline content.

Rheo-NMR Measurements of Cocoa Butter Crystallized Under

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mudge, E.; Mazzanti, G

2009-01-01

Modifications of a benchtop NMR instrument were made to apply temperature control to a shearing NMR cell. This has enabled the determination in situ of the solid fat content (SFC) of cocoa butter under shearing conditions. The cocoa butter was cooled at 3 C/min to three final temperatures of 17.5, 20.0, and 22.5 C with applied shear rates between 45 and 720 s-1. Polymorphic transitions of the cocoa butter were determined using synchrotron X-ray diffraction with an identical shearing system constructed of Lexan. Sheared samples were shown to have accelerated phase transitions compared to static experiments. In experiments where formmore » V was confirmed to be the dominant polymorph, the final SFC averaged around 50%. However, when other polymorphic forms were formed, a lower SFC was measured because the final temperature was within the melting range of that polymorph and only partial crystallization happened. A shear rate of 720 s-1 delayed phase transitions, likely due to viscous heating of the sample. Pulsed NMR is an invaluable tool for determining the crystalline fraction in hydrogen containing materials, yet its use for fundamental and industrial research on fat or alkanes crystallization under shear has only recently been developed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han,W.Q.

Boron nitride (BN) is a synthetic binary compound located between III and V group elements in the Periodic Table. However, its properties, in terms of polymorphism and mechanical characteristics, are rather close to those of carbon compared with other III-V compounds, such as gallium nitride. BN crystallizes into a layered or a tetrahedrally linked structure, like those of graphite and diamond, respectively, depending on the conditions of its preparation, especially the pressure applied. Such correspondence between BN and carbon readily can be understood from their isoelectronic structures [1, 2]. On the other hand, in contrast to graphite, layered BN ismore » transparent and is an insulator. This material has attracted great interest because, similar to carbon, it exists in various polymorphic forms exhibiting very different properties; however, these forms do not correspond strictly to those of carbon. Crystallographically, BN is classified into four polymorphic forms: Hexagonal BN (h-BN) (Figure 1(b)); rhombohedral BN (r-BN); cubic BN (c-BN); and wurtzite BN (w-BN). BN does not occur in nature. In 1842, Balmain [3] obtained BN as a reaction product between molten boric oxide and potassium cyanide under atmospheric pressure. Thereafter, many methods for its synthesis were reported. h-BN and r-BN are formed under ambient pressure. c-BN is synthesized from h-BN under high pressure at high temperature while w-BN is prepared from h-BN under high pressure at room temperature [1]. Each BN layer consists of stacks of hexagonal plate-like units of boron and nitrogen atoms linked by SP{sup 2} hybridized orbits and held together mainly by Van der Waals force (Fig 1(b)). The hexagonal polymorph has two-layered repeating units: AA'AA'... that differ from those in graphite: ABAB... (Figure 1(a)). Within the layers of h-BN there is coincidence between the same phases of the hexagons, although the boron atoms and nitrogen atoms are alternatively located along the c-axis. The rhombohedral system consists of three-layered units: ABCABC..., whose honeycomb layers are arranged in a shifted phase, like as those of graphite. Reflecting its weak interlayer bond, the h-BN can be cleaved easily along its layers, and hence, is widely used as a lubricant material. The material is stable up to a high temperature of 2300 C before decomposition sets in [2] does not fuse a nitrogen atmosphere of 1 atm, and thus, is applicable as a refractory material. Besides having such properties, similar to those of graphite, the material is transparent, and acts as a good electric insulator, especially at high temperatures (10{sup 6} {Omega}m at 1000 C) [1]. c-BN and w-BN are tetrahedrally linked BN. The former has a cubic sphalerite-type structure, and the latter has a hexagonal wurtzite-type structure. c-BN is the second hardest known material (the hardest is diamond), the so-called white diamond. It is used mainly for grinding and cutting industrial ferrous materials because it does not react with molten iron, nickel, and related alloys at high temperatures whereas diamond does [1]. It displays the second highest thermal conductivity (6-9 W/cm.deg) after diamond. This chapter focuses principally upon information about h-BN nanomaterials, mainly BN nanotubes (BNNTs), porous BN, mono- and few-layer-BN sheets. There are good reviews book chapters about c-BN in [1, 4-6].« less

On the polymorphism of benzocaine; a low-temperature structural phase transition for form (II).

PubMed

Chan, Eric J; Rae, A David; Welberry, T Richard

2009-08-01

A low-temperature structural phase transition has been observed for form (II) of benzocaine (BZC). Lowering the temperature doubles the b-axis repeat and changes the space group from P2(1)2(1)2(1) to P112(1) with gamma now 99.37 degrees. The structure is twinned, the twin rule corresponding to a 2(1) screw rotation parallel to a. The phase transition is associated with a sequential displacement parallel to a of zigzag bi-layers of ribbons perpendicular to b*. No similar phase transition was observed for form (I) and this was attributed to the different packing symmetries of the two room-temperature polymorphic forms.

Structure family and polymorphous phase transition in the compounds with soft sublattice: Cu{sub 2}Se as an example

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu, Wujie; State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050; Lu, Ping

Quite a few interesting but controversial phenomena, such as simple chemical composition but complex structures, well-defined high-temperature cubic structure but intriguing phase transition, coexist in Cu{sub 2}Se, originating from the relatively rigid Se framework and “soft” Cu sublattice. However, the electrical transport properties are almost uninfluenced by such complex substructures, which make Cu{sub 2}Se a promising high-performance thermoelectric compound with extremely low thermal conductivity and good power factor. Our work reveals that the crystal structure of Cu{sub 2}Se at the temperature below the phase-transition point (∼400 K) should have a group of candidate structures that all contain a Se-dominated face-centered-cubic-likemore » layered framework but nearly random site occupancy of atoms from the “soft” Cu sublattice. The energy differences among those structures are very low, implying the coexistence of various structures and thus an intrinsic structure complexity with a Se-based framework. Detailed analyses indicate that observed structures should be a random stacking of those representative structure units. The transition energy barriers between each two of those structures are estimated to be zero, leading to a polymorphous phase transition of Cu{sub 2}Se at increasing temperature. Those are all consistent with experimental observations.« less

Association Genetics of Coastal Douglas Fir (Pseudotsuga menziesii var. menziesii, Pinaceae). I. Cold-Hardiness Related Traits

Treesearch

Andrew J. Eckert; Andrew D. Bower; Jill L. Wegrzyn; Barnaly Pande; Kathleen D. Jermstad; Konstantin V. Krutovsky; J. Bradley St. Clair; David B. Neale

2009-01-01

Adaptation to cold is one of the greatest challenges to forest trees. This process is highly synchronized with environmental cues relating to photoperiod and temperature. Here, we use a candidate gene-based approach to search for genetic associations between 384 single-nucleotide polymorphism (SNP) markers from 117 candidate genes and 21 cold-hardiness related traits....

Rotigotine: Unexpected Polymorphism with Predictable Overall Monotropic Behavior.

PubMed

Rietveld, Ivo B; Céolin, René

2015-12-01

Crystallization of polymorphs still has a touch of art, as even prior observations of polymorphs do not guarantee their crystallization. However, once crystals of various polymorphs have been obtained, their relative stabilities can be established with a straightforward thermodynamic approach even if the conclusion will depend on the quality of the experimental data. Rotigotine is an active pharmaceutical ingredient, which has suffered the same setback as Ritonavir: a sudden appearance of a more stable crystalline polymorph than the one used for the formulation. Although the cause of the defect in the formulation was quickly established, the interpretation of the phase behavior of rotigotine has been lacking in clarity. In the present paper, data published in the patents resulting from the discovery of the new polymorph have been used to establish the pressure-temperature phase diagram of the two known solid forms of rotigotine. The analysis clearly demonstrates that form II is the stable solid phase and form I is metastable in the entire pressure-temperature domain: form I is overall monotropic in relation to form II. Thus, it was a sensible decision of European Medicines Agency to ask for a reformulation, as the first formulation was metastable even if crystallization appeared to be very slow. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Impact of storage on dark chocolate: texture and polymorphic changes.

PubMed

Nightingale, Lia M; Lee, Soo-Yeun; Engeseth, Nicki J

2011-01-01

Chocolate storage is critical to final product quality. Inadequate storage, especially with temperature fluctuations, may lead to rearrangement of triglycerides that make up the bulk of the chocolate matrix; this rearrangement may lead to fat bloom. Bloom is the main cause of quality loss in the chocolate industry. The effect of storage conditions leading to bloom formation on texture and flavor attributes by human and instrumental measures has yet to be reported. Therefore, the impact of storage conditions on the quality of dark chocolate by sensory and instrumental measurements was determined. Dark chocolate was kept under various conditions and analyzed at 0, 4, and 8 wk of storage. Ten members of a descriptive panel analyzed texture and flavor. Instrumental methods included texture analysis, color measurement, lipid polymorphism by X-ray diffraction and differential scanning calorimetry, triglyceride concentration by gas chromatography, and surface properties by atomic force microscopy. Results were treated by analysis of variance, cluster analysis, principal component analysis, and linear partial least squares regression analysis. Chocolate stored 8 wk at high temperature without fluctuations and 4 wk with fluctuations transitioned from form V to VI. Chocolates stored at high temperature with and without fluctuations were harder, more fracturable, more toothpacking, had longer melt time, were less sweet, and had less cream flavor. These samples had rougher surfaces, fewer but larger grains, and a heterogeneous surface. Overall, all stored dark chocolate experienced instrumental or perceptual changes attributed to storage condition. Chocolates stored at high temperature with and without fluctuations were most visually and texturally compromised. Practical Application: Many large chocolate companies do their own "in-house" unpublished research and smaller confectionery facilities do not have the means to conduct their own research. Therefore, this study relating sensory and instrumental data provides published evidence available for application throughout the confectionery industry.

Breeding for blast-disease-resistant and high-yield Thai jasmine rice (Oryza sativa L. cv. KDML 105) mutants using low-energy ion beams

NASA Astrophysics Data System (ADS)

Mahadtanapuk, S.; Teraarusiri, W.; Phanchaisri, B.; Yu, L. D.; Anuntalabhochai, S.

2013-07-01

Low-energy ion beam was applied on mutation induction for plant breeding of blast-disease-resistant Thai jasmine rice (Oryza sativa L. cv. KDML 105). Seeds of the wild-type rice were bombarded in vacuum by nitrogen ion beam at energy of 60-80 keV to a beam fluence range of 2 × 1016-2 × 1017 ions/cm2. The ion-bombarded rice seeds were grown in soil for 2 weeks as transplanted rice in plastic pots at 1 seedling/pot. The seedlings were then screened for blast resistance by Pyricularia grisea inoculation with 106 spores/ml concentrations. The blast-resistant rice mutant was planted up to F6 generation with the consistent phenotypic variation. The high percentage of the blast-disease-resistant rice was analyzed with DNA fingerprint. The HAT-RAPD (high annealing temperature-random amplified polymorphic DNA) marker revealed the modified polymorphism fragment presenting in the mutant compared with wild type (KDML 105). The cDNA fingerprints were investigated and the polymorphism fragment was subcloned into pGEM-T easy vector and then sequenced. The sequence of this fragment was compared with those already contained in the database, and the fragment was found to be related to the Spotted leaf protein 11 (Spl11).

Phase equilibria in the NaF-CdO-NaPO3 system at 873 K and crystal structure and physico-chemical characterizations of the new Na2CdPO4F fluorophosphate

NASA Astrophysics Data System (ADS)

Aboussatar, Mohamed; Mbarek, Aïcha; Naili, Houcine; El-Ghozzi, Malika; Chadeyron, Geneviève; Avignant, Daniel; Zambon, Daniel

2017-04-01

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO3 system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO4 side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na2CdPO4F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na2CaPO4F and the fluorosilicate Ca2NaSiO4F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na2MIIPO4F (MII=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and 19F, 23Na, 31P MAS NMR characterizations of Na2CdPO4F have been investigated.

Unraveling the Origin of Structural Disorder in High Temperature Transition Al2O3: Structure of θ-Al2O3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovarik, Libor; Bowden, Mark E.; Shi, Dachuan

The crystallography of transition Al2O3 has been extensively studied in the past due to the advantageous properties of the oxide in catalytic and a range of other technological applications. However, existing crystallographic models are insufficient to describe the structure of many important Al2O3 polymorphs due to their highly disordered nature. In this work, we investigate structure and disorder in high-temperature treated transition Al2O3, and provide a structural description for θ-Al2O3 by using a suite of complementary imaging, spectroscopy and quantum calculation techniques. Contrary to current understanding, our high-resolution imaging shows that θ-Al2O3 is a disordered composite phase of at leastmore » two different end members. By correlating imaging and spectroscopy results with DFT calculations, we propose a model that describes θ-Al2O3 as a disordered intergrowth of two crystallographic variants at the unit cell level. One variant is based on β-Ga2O3, and the other on a monoclinic phase that is closely-related to δ-Al2O3. The overall findings and interpretations afford new insight into the origin of poor crystallinity in transition Al2O3, and also provide new perspectives on structural complexity that can emerge from intergrowth of closely related structural polymorphs.« less

Influence of solvent polarity and supersaturation on template-induced nucleation of carbamazepine crystal polymorphs

NASA Astrophysics Data System (ADS)

Parambil, Jose V.; Poornachary, Sendhil K.; Tan, Reginald B. H.; Heng, Jerry Y. Y.

2017-07-01

Studies on the use of template surfaces to induce heterogeneous crystal nucleation have gained momentum in recent years-with potential applications in selective crystallisation of polymorphs and in the generation of seed crystals in a continuous crystallisation process. In developing a template-assisted solution crystallisation process, the kinetics of homogeneous versus heterogeneous crystal nucleation could be influenced by solute-solvent, solute-template, and solvent-template interactions. In this study, we report the effect of solvents of varying polarity on the nucleation of carbamazepine (CBZ) crystal polymorphs, a model active pharmaceutical ingredient. The experimental results demonstrate that functionalised template surfaces are effective in promoting crystallisation of either the metastable (form II) or stable (form III) polymorphs of CBZ only in moderately (methanol, ethanol, isopropanol) and low polar (toluene) solvents. A solvent with high polarity (acetonitrile) is thought to mask the template effect on heterogeneous nucleation due to strong solute-solvent and solvent-template interactions. The current study highlights that a quality-by-design (QbD) approach-considering the synergistic effects of solute concentration, solvent type, solution temperature, and template surface chemistry on crystal nucleation-is critical to the development of a template-induced crystallisation process.

Mismatch cleavage by single-strand specific nucleases

PubMed Central

Till, Bradley J.; Burtner, Chris; Comai, Luca; Henikoff, Steven

2004-01-01

We have investigated the ability of single-strand specific (sss) nucleases from different sources to cleave single base pair mismatches in heteroduplex DNA templates used for mutation and single-nucleotide polymorphism analysis. The TILLING (Targeting Induced Local Lesions IN Genomes) mismatch cleavage protocol was used with the LI-COR gel detection system to assay cleavage of amplified heteroduplexes derived from a variety of induced mutations and naturally occurring polymorphisms. We found that purified nucleases derived from celery (CEL I), mung bean sprouts and Aspergillus (S1) were able to specifically cleave nearly all single base pair mismatches tested. Optimal nicking of heteroduplexes for mismatch detection was achieved using higher pH, temperature and divalent cation conditions than are routinely used for digestion of single-stranded DNA. Surprisingly, crude plant extracts performed as well as the highly purified preparations for this application. These observations suggest that diverse members of the S1 family of sss nucleases act similarly in cleaving non-specifically at bulges in heteroduplexes, and single-base mismatches are the least accessible because they present the smallest single-stranded region for enzyme binding. We conclude that a variety of sss nucleases and extracts can be effectively used for high-throughput mutation and polymorphism discovery. PMID:15141034

An Opposite Pattern to the Conventional Thermal Hypothesis: Temperature-Dependent Variation in Coloration of Adults of Saccharosydne procerus (Homoptera: Delphacidae)

PubMed Central

Yin, Haichen; Shakeel, Muhammad; Kuang, Jing; Li, Jianhong

2015-01-01

Melanism is a common polymorphism in many insect species that also influences immune function. According to the thermal melanin hypothesis, ectothermic individuals from cooler environments have darker cuticles and higher polyphenol oxidase (PO) levels, which represent a better immunocompetence. In this study, the links among environmental temperature, melanism, and PO activity of Saccharosydne procerus (Matsumura) were examined. Most S. procerus have a black spot on their forewings at high temperatures in the field and in the laboratory. In PO activity assay, a positive association between PO level and temperature was found. Our results showed that a diversification of melanism occurred under different temperatures and that melanism in S. procerus presented an opposite pattern to the one proposed by the thermal hypothesis. PMID:26024474

Survey and analysis of crystal polymorphism in organic structures

PubMed Central

Kaur, Ramanpreet

2018-01-01

With the intention of producing the most comprehensive treatment of the prevalence of crystal polymorphism among structurally characterized materials, all polymorphic compounds flagged as such within the Cambridge Structural Database (CSD) are analysed and a list of crystallographically characterized organic polymorphic compounds is assembled. Classifying these structures into subclasses of anhydrates, salts, hydrates, non-hydrated solvates and cocrystals reveals that there are significant variations in polymorphism prevalence as a function of crystal type, a fact which has not previously been recognized in the literature. It is also shown that, as a percentage, polymorphic entries are decreasing temporally within the CSD, with the notable exception of cocrystals, which continue to rise at a rate that is a constant fraction of the overall entries. Some phenomena identified that require additional scrutiny include the relative prevalence of temperature-induced phase transitions among organic salts and the paucity of polymorphism in crystals with three or more chemical components. PMID:29765601

Shell colour, temperature, (micro)habitat structure and predator pressure affect the behaviour of Cepaea nemoralis

NASA Astrophysics Data System (ADS)

Rosin, Zuzanna M.; Kwieciński, Zbigniew; Lesicki, Andrzej; Skórka, Piotr; Kobak, Jarosław; Szymańska, Anna; Osiejuk, Tomasz S.; Kałuski, Tomasz; Jaskulska, Monika; Tryjanowski, Piotr

2018-06-01

Although shell colour polymorphism of the land snail Cepaea nemoralis is a well-known phenomenon, proximate and ultimate factors driving its evolution remain uncertain. Polymorphic species show variation in behavioural responses to selective forces. Therefore, we estimated effects of various environmental factors (temperature, humidity, food availability, (micro)habitat structure and predatory pressure) on behavioural response (frequency of locomotion, climbing and hiding) of C. nemoralis morphs, in experimental and natural conditions. In the experimental part of study, the frequency of locomotion was negatively affected by temperature and the presence of food and positively influenced by the presence of light. Morphs significantly differed in behavioural responses to environmental variability. Pink mid-banded and yellow five-banded morphs climbed less often and hide in shelter more often than yellow and pink unbanded individuals when temperature was low and food was absent. Snails fed most often at moderate temperature compared to low and high temperatures. Field investigations partially confirmed differences among morphs in frequency of climbing, but not in terms of probability of hiding in sheltered sites. In natural colonies, temperature and (micro)habitat structure significantly affected frequency of climbing as well as hiding in shelter. Snails more often hid in sheltered sites where thrushes preyed on Cepaea. Tendency of unbanded morphs to climb trees may have evolved under avian predatory pressure as thrushes forage on a ground. Tendency of banded morphs to hide in sheltered sites may reflect prey preferences for cryptic background. The results implicate that differential behaviour of C. nemoralis morphs compensate for their morphological and physiological limitations of adaptation to habitat.

Shell colour, temperature, (micro)habitat structure and predator pressure affect the behaviour of Cepaea nemoralis.

PubMed

Rosin, Zuzanna M; Kwieciński, Zbigniew; Lesicki, Andrzej; Skórka, Piotr; Kobak, Jarosław; Szymańska, Anna; Osiejuk, Tomasz S; Kałuski, Tomasz; Jaskulska, Monika; Tryjanowski, Piotr

2018-05-09

Although shell colour polymorphism of the land snail Cepaea nemoralis is a well-known phenomenon, proximate and ultimate factors driving its evolution remain uncertain. Polymorphic species show variation in behavioural responses to selective forces. Therefore, we estimated effects of various environmental factors (temperature, humidity, food availability, (micro)habitat structure and predatory pressure) on behavioural response (frequency of locomotion, climbing and hiding) of C. nemoralis morphs, in experimental and natural conditions. In the experimental part of study, the frequency of locomotion was negatively affected by temperature and the presence of food and positively influenced by the presence of light. Morphs significantly differed in behavioural responses to environmental variability. Pink mid-banded and yellow five-banded morphs climbed less often and hide in shelter more often than yellow and pink unbanded individuals when temperature was low and food was absent. Snails fed most often at moderate temperature compared to low and high temperatures. Field investigations partially confirmed differences among morphs in frequency of climbing, but not in terms of probability of hiding in sheltered sites. In natural colonies, temperature and (micro)habitat structure significantly affected frequency of climbing as well as hiding in shelter. Snails more often hid in sheltered sites where thrushes preyed on Cepaea. Tendency of unbanded morphs to climb trees may have evolved under avian predatory pressure as thrushes forage on a ground. Tendency of banded morphs to hide in sheltered sites may reflect prey preferences for cryptic background. The results implicate that differential behaviour of C. nemoralis morphs compensate for their morphological and physiological limitations of adaptation to habitat.

Polymorphisms in xenobiotic metabolizing genes, intakes of heterocyclic amines and red meat, and postmenopausal breast cancer

PubMed Central

Lee, Hae-Jeung; Wu, Kana; Cox, David G.; Hunter, David; Hankinson, Susan E.; Willett, Walter C.; Sinha, Rashmi; Cho, Eunyoung

2013-01-01

Heterocyclic amines (HCAs) are mutagenic compounds generated when meats are cooked at high temperature and for long duration. The findings from previous studies on the relation between HCAs and breast cancer are inconsistent, possibly due to genetic variations in the enzymes metabolizing HCAs. To evaluate whether the associations of intakes of estimated HCAs, meat-derived mutagenicity (MDM), and red meat with risk of postmenopausal breast cancer were modified by N-acetyltransferase 2 (NAT2) acetylator genotype or cytochrome P450 1A2 -164 A/C (CYP1A2) polymorphism, we conducted a nested case-control study with 579 cases and 981 controls within a prospective cohort, the Nurses’ Health Study (NHS). HCAs and MDM intakes were derived using a cooking method questionnaire administered in 1996. NAT2 acetylator genotype, the CYP1A2 polymorphism, and intakes of HCAs, MDM, and red meat were not associated with risk of postmenopausal breast cancer. There was also no interaction between NAT2 acetylator genotype or CYP1A2 polymorphism and HCAs and MDM and red meat intake in relation to breast cancer. These results do not support the hypothesis that genetic polymorphisms of xenobiotic enzymes involved in the metabolism of HCAs may modify the associations between intakes of red meat or meat-related mutagens and breast cancer risk. PMID:24099317

Structure-property relationship of supramolecular ferroelectric [H-66dmbp][Hca] accompanied by high polarization, competing structural phases, and polymorphs.

PubMed

Kobayashi, Kensuke; Horiuchi, Sachio; Ishibashi, Shoji; Kagawa, Fumitaka; Murakami, Youichi; Kumai, Reiji

2014-12-22

Three polymorphic forms of 6,6'-dimethyl-2,2'-bipyridinium chloranilate crystals were characterized to understand the origin of polarization properties and the thermal stability of ferroelectricity. According to the temperature-dependent permittivity, differential scanning calorimetry, and X-ray diffraction, structural phase transitions were found in all polymorphs. Notably, the ferroelectric α-form crystal, which has the longest hydrogen bond (2.95 Å) among the organic acid/base-type supramolecular ferroelectrics, transformed from a polar structure (space group, P21) into an anti-polar structure (space group, P21/c) at 378 K. The non-ferroelectric β- and γ-form crystals also exhibited structural rearrangements around hydrogen bonds. The hydrogen-bonded geometry and ferroelectric properties were compared with other supramolecular ferroelectrics. A positive relationship between the phase-transition temperature (TC ) and hydrogen-bond length () was observed, and was attributed to the potential barrier height for proton off-centering or order/disorder phenomena. The optimized spontaneous polarization (Ps ) agreed well with the results of the first-principles calculations, and could be amplified by separating the two equilibrium positions of protons with increasing . These data consistently demonstrated that stretching is a promising way to enhance the polarization performance and thermal stability of hydrogen-bonded organic ferroelectrics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature dependent polymorphism of pyrazinamide: An in situ Raman and DFT study

NASA Astrophysics Data System (ADS)

Sharma, Poornima; Nandi, Rajib; Gangopadhyay, Debraj; Singh, Anurag; Singh, Ranjan K.

2018-02-01

The α and γ polymorphs of drug pyrazinamide have been detected with the help of temperature dependent Raman spectroscopic technique. Pyrazinamide is a very useful drug used for the treatment of tuberculosis (TB) and plays a significant role in destroying the dormant tubercle bacilli which are not destroyed by other common TB drugs. Temperature dependent Raman spectra suggest polymorphic phase change from α → γ form of pyrazinamide between 145 and 146 °C. In situ Raman spectra of pyrazinamide between 145 and 146 °C show the conversion of α → γ form by the shift in Cdbnd O stretching vibration accompanied by several other changes. The phase change is characterized by the breaking of two linear Nsbnd H ⋯ O type hydrogen bonds associated with Cdbnd O stretching vibration in α dimer and formation of one linear Nsbnd H ⋯ N type hydrogen bond along with a weak intramolecular Csbnd H ⋯ O type hydrogen bond in the γ dimer.

Shear induced structures in crystallizing cocoa butter

NASA Astrophysics Data System (ADS)

Mazzanti, Gianfranco; Guthrie, Sarah E.; Sirota, Eric B.; Marangoni, Alejandro G.; Idziak, Stefan H. J.

2004-03-01

Cocoa butter is the main structural component of chocolate and many cosmetics. It crystallizes in several polymorphs, called phases I to VI. We used Synchrotron X-ray diffraction to study the effect of shear on its crystallization. A previously unreported phase (phase X) was found and a crystallization path through phase IV under shear was observed. Samples were crystallized under shear from the melt in temperature controlled Couette cells, at final crystallization temperatures of 17.5^oC, 20^oC and 22.5^oC in Beamline X10A of NSLS. The formation of phase X was observed at low shear rates (90 s-1) and low crystallization temperature (17.5^oC), but was absent at high shear (720 s-1) and high temperature (20^oC). The d-spacing and melting point suggest that this new phase is a mixture rich on two of the three major components of cocoa butter. We also found that, contrary to previous reports, the transition from phase II to phase V can happen through the intermediate phase IV, at high shear rates and temperature.

High-pressure synthesis of mesoporous stishovite: potential applications in mineral physics

NASA Astrophysics Data System (ADS)

Stagno, Vincenzo; Mandal, Manik; Landskron, Kai; Fei, Yingwei

2015-06-01

Recently, we have described a successful synthesis route to obtain mesoporous quartz and its high-pressure polymorph coesite by nanocasting at high pressure using periodic mesostructured precursors, such as SBA-16 and FDU-12/carbon composite as starting materials. Periodic mesoporous high-pressure silica polymorphs are of particular interest as they combine transport properties and physical properties such as hardness that potentially enable the industrial use of these materials. In addition, synthesis of mesoporous crystalline silica phases can allow more detailed geology-related studies such as water/mineral interaction, dissolution/crystallization rate and the surface contribution to the associated thermodynamic stability (free energy and enthalpy) of the various polymorphs and their crossover. Here, we present results of synthesis of mesoporous stishovite from cubic large-pore periodic mesoporous silica LP-FDU-12/C composite as precursor with an fcc lattice. We describe the synthesis procedure using multi-anvil apparatus at 9 GPa (about 90,000 atm) and temperature of 500 °C. The synthetic mesoporous stishovite is, then, characterized by wide and small-angle X-ray diffraction, scanning/transmission electron microscopy and gas adsorption. Results show that this new material is characterized by accessible mesopores with wide pore size distribution, surface area of ~45 m2/g and volume of pores of ~0.15 cm3/g. Results from gas adsorption indicate that both porosity and permeability are retained at the high pressures of synthesis but with weak periodic order of the pores.

An Assessment of Molecular Dynamic Force Fields for Silica for Use in Simulating Laser Damage Mitigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soules, T F; Gilmer, G H; Matthews, M J

2010-10-21

We compare force fields (FF's) that have been used in molecular dynamic (MD) simulations of silica in order to assess their applicability for use in simulating IR-laser damage mitigation. Although pairwise FF?s obtained by fitting quantum mechanical calculations such as the BKS and CHIK potentials have been shown to reproduce many of the properties of silica including the stability of silica polymorphs and the densification of the liquid, we show that melting temperatures and fictive temperatures are much too high. Softer empirical force fields give liquid and glass properties at experimental temperatures but may not predict all properties important tomore » laser mitigation experiments.« less

Microstructure of calcite deformed by high-pressure torsion: An X-ray line profile study

NASA Astrophysics Data System (ADS)

Schuster, Roman; Schafler, Erhard; Schell, Norbert; Kunz, Martin; Abart, Rainer

2017-11-01

Calcite aggregates were deformed to high strain using high-pressure torsion and applying confining pressures of 1-6 GPa and temperatures between room temperature and 450 °C. The run products were characterized by X-ray diffraction, and key microstructural parameters were extracted employing X-ray line profile analysis. The dominant slip system was determined as r { 10 1 bar 4 } ⟨ 2 bar 021 ⟩ with edge dislocation character. The resulting dislocation density and the size of the coherently scattering domains (CSD) exhibit a systematic dependence on the P-T conditions of deformation. While high pressure generally impedes recovery through reducing point defect mobility, the picture is complicated by pressure-induced phase transformations in the CaCO3 system. Transition from the calcite stability field to those of the high-pressure polymorphs CaCO3-II, CaCO3-III and CaCO3-IIIb leads to a change of the microstructural evolution with deformation. At 450 °C and pressures within the calcite stability field, dislocation densities and CSD sizes saturate at shear strains exceeding 10 in agreement with earlier studies at lower pressures. In the stability field of CaCO3-II, the dislocation density exhibits a more complex behavior. Furthermore, at a given strain and strain rate, the dislocation density increases and the CSD size decreases with increasing pressure within the stability fields of either calcite or of the high-pressure polymorphs. There is, however, a jump from high dislocation densities and small CSDs in the upper pressure region of the calcite stability field to lower dislocation densities and larger CSDs in the low-pressure region of the CaCO3-II stability field. This jump is more pronounced at higher temperatures and less so at room temperature. The pressure influence on the deformation-induced evolution of dislocation densities implies that pressure variations may change the rheology of carbonate rocks. In particular, a weakening is expected to occur at the transition from the calcite to the CaCO3-II stability field, if aragonite does not form.

Negative thermal expansion materials related to cubic zirconium tungstate

NASA Astrophysics Data System (ADS)

Lind, Cora

2001-12-01

A non-hydrolytic sol-gel method for the preparation of ZrW2O 8 was developed. A new trigonal polymorph was discovered, which is structurally related to trigonal ZrMO2O8 and MnRe2O 8 as evidenced by powder x-ray diffraction and EXAFS studies. Seeding of the starting mixtures with cubic ZrW2O8 promoted crystallization of the cubic phase instead of trigonal material. Dehydration of ZrW2O7(OH)2·2H 2O gave cubic ZrW2O8 at 650°C, and a modification of this route led to the discovery of the new NTE materials cubic ZrMo 2O8 and HfMo2O8. These compounds crystallize in the same temperature range as the more stable trigonal AMo2O 8 polymorphs. To facilitate preparation of phase pure cubic molybdates, the influence of precursor chemistry on the crystallization behavior was investigated. The synthesis was extended to the solid solution system ZrxHf 1-xMoyW2-yO8 (0 ≤ x ≤ 1, 0 ≤ y ≤ 2). All compounds showed negative thermal expansion between 77 and 573 K. High-pressure in situ diffraction experiments were conducted on several AM2O8 polymorphs. With the exception of monoclinic ZrMo2O8, all materials underwent at least one pressure induced phase transition. Quasi-hydrostatic experiments on cubic AMo 2O8 led to a reversible transition to a new high-pressure structure, while low-pressure amorphization was observed under non-hydrostatic conditions. Isothermal kinetic studies of the cubic to trigonal transformation for ZrMo2O8 were carried out on four samples. Apparent activation energies of 170--290 kJ/mol were obtained using an Avrami model in combination with an Arrhenius analysis. This corresponds to 5% conversion levels after one year at temperatures between 220 and 315°C. Ex situ studies showed that the conversion at lower temperatures was considerably slower than what would be expected from extrapolation of the kinetic data. Drop solution calorimetry was carried out on several polymorphs of ZrMo 2O8, HfMo2O8 and ZrW2O 8. Only monoclinic ZrMo2O8 was enthalpically stabilized with respect to the binary oxides. For all other polymorphs, the differences in enthalpies of formation from the binary oxides for each AM2O 8 system (A = Zr, Hf; M = Mo, W) were small. Attempts to synthesize new materials MIIRe2O 8 (M = Mg, Zn, Mn, Co) with the cubic ZrW2O8 structure from a hydrate precursor were not successful.

Magnetic characteristics of polymorphic single crystal compounds DyIr2Si2

NASA Astrophysics Data System (ADS)

Uchima, Kiyoharu; Shigeoka, Toru; Uwatoko, Yoshiya

2018-05-01

We have confirmed that the tetragonal ternary compound DyIr2Si2 shows polymorphism; the ThCr2Si2-type structure as a low temperature phase (I-phase) and the CaBe2Ge2-type one as a high temperature phase (P-phase) exist. A comparative study on magnetic characteristics of the morphs was performed on the I- and P-phase single crystals in order to elucidate how magnetic properties are influenced by crystallographic symmetry. The magnetic behavior changes drastically depending on the structure. The DyIr2Si2(I) shows an antiferromagnetic ordering below TN = 30 K, additional magnetic transitions of T1 = 17 K and T2 = 10 K, and a strong uniaxial magnetic anisotropy with the easy [001] direction. The [001] magnetization shows four metamagnetic transitions at low temperatures. On the other hand, the DyIr2Si2(P) has comparatively low ordering temperature of TN1 = 9.4 K and an additional transition temperature of TN2 = 3.0 K, and exhibits an easy-plane magnetic anisotropy with the easy [110] direction. Two metamagnetic transitions appear in the basal plane magnetization processes. In both the morphs, the χ-T behavior suggests the existence of component-separated magnetic transitions. The ab-component of magnetic moments orders at the higher transition temperature TN1 for the P-phase compound, which is contrast to the I-phase behavior; the c-component orders firstly at TN. The crystalline electric field (CEF) analysis was made, and the difference in magnetic behaviors between both the morphs is explained by the CEF effects.

Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied

NASA Technical Reports Server (NTRS)

Farmer, Serene C.; Sayir, Ali

2001-01-01

Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.

Diffuse Scattering as an Aid to the Understanding of Polymorphism in Pharmaceuticals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welberry, T.R.; Chan, E.J.; Goossens, D.J.

Polymorphism occurs when the same molecular compound can crystallize in more than one distinct crystal structure. Its study is a field of great interest and activity. This is largely driven by its importance in the pharmaceutical industry, but polymorphism is also an issue in the pigments, dyes, and explosives industries. The polymorph formed by a compound generally exerts a strong influence on its solid-state properties. The polymorphic form of a drug molecule may affect the ease of manufacture and processing, shelf life, and most significantly the rate of uptake of the molecule by the human body. They can even varymore » in toxicity; one polymorph may be safe, while a second may be toxic. In this review of recently published work, we show how diffuse scattering experiments coupled with Monte Carlo (MC) computer modeling can aid in the understanding of polymorphism. Examples of the two common pharmaceuticals, benzocaine and aspirin, both of which are bimorphic, at ambient temperatures, are discussed.« less

Diffuse Scattering as an Aid to the Understanding of Polymorphism in Pharmaceuticals

NASA Astrophysics Data System (ADS)

Welberry, T. R.; Chan, E. J.; Goossens, D. J.; Heerdegen, A. P.

2012-05-01

Polymorphism occurs when the same molecular compound can crystallize in more than one distinct crystal structure. Its study is a field of great interest and activity. This is largely driven by its importance in the pharmaceutical industry, but polymorphism is also an issue in the pigments, dyes, and explosives industries. The polymorph formed by a compound generally exerts a strong influence on its solid-state properties. The polymorphic form of a drug molecule may affect the ease of manufacture and processing, shelf life, and most significantly the rate of uptake of the molecule by the human body. They can even vary in toxicity; one polymorph may be safe, while a second may be toxic. In this review of recently published work, we show how diffuse scattering experiments coupled with Monte Carlo (MC) computer modeling can aid in the understanding of polymorphism. Examples of the two common pharmaceuticals, benzocaine and aspirin, both of which are bimorphic, at ambient temperatures, are discussed.

The structure, thermal expansion and phase transition properties of Ho{sub 2}Mo{sub 3−x}W{sub x}O{sub 12} (x = 0, 1.0, 2.0) solid solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, X.Z.; Hao, L.J.; Wu, M.M.

Graphical abstract: A polymorph with Gd{sub 2}Mo{sub 3}O{sub 12}-type structure (space group: Pba2) for negative thermal expansion material Ho{sub 2}Mo{sub 3}O{sub 12} is observed above 700 °C, this polymorphism could be effectively supressed by W-substiution for Mo, the give the temperature dependence of Pba2 phase contents for Ho{sub 2}Mo{sub 3−x}W{sub x}O{sub 12} (x = 0.0, 1.0, 2.0). - Highlights: • The solid solution Ho{sub 2}Mo{sub 3−x}W{sub x}O{sub 12} was investigated by in situ X-ray diffraction. • It is found that the substitution slightly influence thermal expansion property. • A polymorph of Ho{sub 2}Mo{sub 3}O{sub 12} with Pba2 space group wasmore » observed above 700 °C. • The W-substitution for Mo effectively suppresses this transformation. - Abstract: Three solid solutions of Ho{sub 2}Mo{sub 3−x}W{sub x}O{sub 12}(x = 0, 1.0, 2.0) were prepared by solid state reaction method, the temperature dependent in-situ X-ray diffraction and thermal analysis were performed to investigate their structure and thermal expansion. All samples have orthorhombic structure(space group Pbcn# 60) with negative thermal expansion at the room temperature. the substitution of W for Mo enlarges the lattice constant and slightly influences the negative thermal expansion. An irreversible phase transformation to the Pba2 phase(Tb{sub 2}Mo{sub 3}O{sub 12} structure) was observed at high temperature for Mo-rich samples. This ploymorphism could be effectively suppressed by the W-substitution for Mo, this phenomenon could be explained by the lower electronegativity of W{sup 6+} than Mo{sup 6+}.« less

Stimulus-Responsive Nanoparticles and Associated (Reversible) Polymorphism via Polymerization Induced Self-assembly (PISA).

PubMed

Pei, Yiwen; Lowe, Andrew B; Roth, Peter J

2017-01-01

Polymerization-induced self-assembly (PISA) is an extremely versatile method for the in situ preparation of soft-matter nanoparticles of defined size and morphologies at high concentrations, suitable for large-scale production. Recently, certain PISA-prepared nanoparticles have been shown to exhibit reversible polymorphism ("shape-shifting"), typically between micellar, worm-like, and vesicular phases (order-order transitions), in response to external stimuli including temperature, pH, electrolytes, and chemical modification. This review summarises the literature to date and describes molecular requirements for the design of stimulus-responsive nano-objects. Reversible pH-responsive behavior is rationalised in terms of increased solvation of reversibly ionized groups. Temperature-triggered order-order transitions, conversely, do not rely on inherently thermo-responsive polymers, but are explained based on interfacial LCST or UCST behavior that affects the volume fractions of the core and stabilizer blocks. Irreversible morphology transitions, on the other hand, can result from chemical post-modification of reactive PISA-made particles. Emerging applications and future research directions of this "smart" nanoparticle behavior are reviewed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identity and diversity of coral endosymbionts (zooxanthellae) from three Palauan reefs with contrasting bleaching, temperature and shading histories.

PubMed

Fabricius, K E; Mieog, J C; Colin, P L; Idip, D; van Oppen, M J H

2004-08-01

The potential of corals to associate with more temperature-tolerant strains of algae (zooxanthellae, Symbiodinium) can have important implications for the future of coral reefs in an era of global climate change. In this study, the genetic identity and diversity of zooxanthellae was investigated at three reefs with contrasting histories of bleaching mortality, water temperature and shading, in the Republic of Palau (Micronesia). Single-stranded conformation polymorphism and sequence analysis of the ribosomal DNA internal transcribed spacer (ITS)1 region was used for genotyping. A chronically warm but partly shaded coral reef in a marine lake that is hydrographically well connected to the surrounding waters harboured only two single-stranded conformation polymorphism profiles (i.e. zooxanthella communities). It consisted only of Symbiodinium D in all 13 nonporitid species and two Porites species investigated, with the remaining five Porites harbouring C*. Despite the high temperature in this lake (> 0.5 degrees above ambient), this reef did not suffer coral mortality during the (1998) bleaching event, however, no bleaching-sensitive coral families and genera occur in the coral community. This setting contrasts strongly with two other reefs with generally lower temperatures, in which 10 and 12 zooxanthella communities with moderate to low proportions of clade D zooxanthellae were found. The data indicate that whole coral assemblages, when growing in elevated seawater temperatures and at reduced irradiance, can be composed of colonies associated with the more thermo-tolerant clade D zooxanthellae. Future increases in seawater temperature might, therefore, result in an increasing prevalence of Symbiodinium phylotype D in scleractinian corals, possibly associated with a loss of diversity in both zooxanthellae and corals. Copyright 2004 Blackwell Publishing Ltd

Pressure-induced changes of the structure and properties of monoclinic α -chalcocite Cu2S

NASA Astrophysics Data System (ADS)

Zimmer, D.; Ruiz-Fuertes, J.; Morgenroth, W.; Friedrich, A.; Bayarjargal, L.; Haussühl, E.; Santamaría-Pérez, D.; Frischkorn, S.; Milman, V.; Winkler, B.

2018-04-01

The high-pressure behavior of monoclinic (P 21/c ) α -chalcocite, Cu2S , was investigated at ambient temperature by single-crystal x-ray diffraction, electrical resistance measurements, and optical absorption spectroscopy up to 16 GPa. The experiments were complemented by density-functional-theory-based calculations. Single-crystal x-ray diffraction data show that monoclinic α -chalcocite undergoes two pressure-induced first-order phase transitions at ˜3.1 and ˜7.1 GPa. The crystal structure of the first high-pressure polymorph, HP1, was solved and refined in space group P 21/c with a =10.312 (4 )Å , b =6.737 (3 )Å , c =7.305 (1 )Å , and β =100.17 (2) ∘ at 6.2(3) GPa. The crystal structure of the second high-pressure polymorph, HP2, was solved and refined in space group P 21/c with a =6.731 (4 )Å , b =6.689 (2 )Å , c =6.967 (8 )Å , and β =93.18 (3) ∘ at 7.9(4) GPa. Electrical resistance measurements upon compression and optical absorption experiments upon decompression show that the structural changes in α -chalcocite are accompanied by changes of the electrical and optical properties. Upon pressure release, the band gap Eg of α -chalcocite (1.24 eV at ambient conditions) widens across the first structural phase transition, going from 1.24 eV at 2.2 GPa (α -chalcocite) to 1.35 eV at 2.6 GPa (HP1), and closes significantly across the second phase transition, going from 1.32 eV at 4.4 GPa (HP1) to 0.87 eV at 4.9 GPa (HP2). The electrical resistance shows similar behavior: its highest value is for the first high-pressure polymorph (HP1), and its lowest value is for the second high-pressure polymorph (HP2) of α -chalcocite. These results are interpreted on the basis of calculated electronic band structures.

Solid-state characterization and impurities determination of fluconazol generic products marketed in Morocco

PubMed Central

Bourichi, Houda; Brik, Youness; Hubert, Philipe; Cherrah, Yahia; Bouklouze, Abdelaziz

2012-01-01

In this paper, we report the results of quality control based in physicochemical characterization and impurities determination of three samples of fluconazole drug substances marketed in Morocco. These samples were supplied by different pharmaceuticals companies. The sample A, as the discovered product, was supplied by Pfizer, while samples B and C (generics), were manufactured by two different Indian industries. Solid-state characterization of the three samples was realized with different physicochemical methods as: X-ray powder diffraction, Fourier-transformation infrared spectroscopy, differential scanning calorimetry. High performance liquid chromatography was used to quantify the impurities in the different samples. The results from the physicochemical methods cited above, showed difference in polymorph structure of the three drug substances. Sample A consisted in pure polymorph III, sample B consisted in pure polymorph II, sample C consisted in a mixture of fluconazole Form III, form II and the monohydrate. This result was confirmed by differential scanning calorimetry. Also it was demonstrated that solvents used during the re-crystallization step were among the origins of these differences in the structure form. On the other hand, the result of the stability study under humidity and temperature showed that fluconazole polymorphic transformation could be owed to the no compliance with the conditions of storage. The HPLC analysis of these compounds showed the presence of specific impurities for each polymorphic form, and a possible relationship could be exist between impurities and crystalline form of fluconazole. PMID:29403776

Conformational polymorphism and thermochemical analysis of 5,5' ''-bis[(2,2,5,5-tetramethyl-1-aza-2,5-disila-1-cyclopentyl)ethyl]-2,2':5',2' ':5' ',2' ''-quaterthiophene.

PubMed

Muguruma, Hitoshi; Hotta, Shu

2006-11-23

The titled compound exists as two polymorphic solid phases (denoted form-I and form-II). Form-I obtained by as-synthesized material is a more stable phase. Form-II is a less stable phase. Spontaneous solid-solid transformation from form-II to form-I is observed in the temperature range between room temperature and the melting point of form-I (Tm = 156.5 degrees C), and its activation energy is estimated to be 96 kJ mol-1 by Arrhenius plot. The solid-solute-solid transformation (recrystallization from solution) from form-II to form-I is also observed. In contrast, form-II is obtained only by a solid-melt-solid transformation from form-I. Therefore, the system of two polymorphs is monotropic. The solid-state NMR measurement shows that form-I has the molecular conformation of complete S-syn-anti-syn in the oligothiophene backbone, whereas form-II has that of S-all-anti. With the solution NMR data, the polymorphism could not be observed. Therefore, the polymorphs originate from the different molecular packing involving the conformational change of the molecule. This unique property is attributed to the extra bulky terminal groups of the compounds. However, despite the extra bulky terminal groups, the mentioned polymorphism is not observed in the titled compound analogue which has S-all-anti conformation (like form-II).

Nucleation control and separation of paracetamol polymorphs through swift cooling crystallization process

NASA Astrophysics Data System (ADS)

Sudha, C.; Srinivasan, K.

2014-09-01

Polymorphic nucleation behavior of pharmaceutical solid paracetamol has been investigated by performing swift cooling crystallization process. Saturated aqueous solution prepared at 318 K was swiftly cooled to 274 K in steps of every 1 K in the temperature range from 274 K to 313 K with uniform stirring of 100 rpm. The resultant supersaturation generated in the mother solution favours the nucleation of three different polymorphs of paracetamol. Lower supersaturation region σ=0.10-0.83 favours stable mono form I; the intermediate supersaturation region σ=0.92-1.28 favours metastable ortho form II and the higher supersaturation region σ=1.33-1.58 favours unstable form III polymorphic nucleation. Depending upon the level of supersaturation generated during swift cooling process and the corresponding solubility limit and metastable zone width (MSZW) of each polymorph, the nucleation of a particular polymorph occurs in the system. The type of polymorphs was identified by in-situ optical microscopy and the internal structure was confirmed by Powder X-ray diffraction (PXRD) study. By this novel approach, the preferred nucleation regions of all the three polymorphs of paracetamol are optimized in terms of different cooling ranges employed during the swift cooling process. Also solution mediated polymorphic transformations from unstable to mono and ortho to mono polymorphs have been studied by in-situ.

Adapting phase-switch Monte Carlo method for flexible organic molecules

NASA Astrophysics Data System (ADS)

Bridgwater, Sally; Quigley, David

2014-03-01

The role of cholesterol in lipid bilayers has been widely studied via molecular simulation, however, there has been relatively little work on crystalline cholesterol in biological environments. Recent work has linked the crystallisation of cholesterol in the body with heart attacks and strokes. Any attempt to model this process will require new models and advanced sampling methods to capture and quantify the subtle polymorphism of solid cholesterol, in which two crystalline phases are separated by a phase transition close to body temperature. To this end, we have adapted phase-switch Monte Carlo for use with flexible molecules, to calculate the free energy between crystal polymorphs to a high degree of accuracy. The method samples an order parameter , which divides a displacement space for the N molecules, into regions energetically favourable for each polymorph; which is traversed using biased Monte Carlo. Results for a simple model of butane will be presented, demonstrating that conformational flexibility can be correctly incorporated within a phase-switching scheme. Extension to a coarse grained model of cholesterol and the resulting free energies will be discussed.

Intragenomic polymorphisms among high-copy loci: a genus-wide study of nuclear ribosomal DNA in Asclepias (Apocynaceae).

PubMed

Weitemier, Kevin; Straub, Shannon C K; Fishbein, Mark; Liston, Aaron

2015-01-01

Despite knowledge that concerted evolution of high-copy loci is often imperfect, studies that investigate the extent of intragenomic polymorphisms and comparisons across a large number of species are rarely made. We present a bioinformatic pipeline for characterizing polymorphisms within an individual among copies of a high-copy locus. Results are presented for nuclear ribosomal DNA (nrDNA) across the milkweed genus, Asclepias. The 18S-26S portion of the nrDNA cistron of Asclepias syriaca served as a reference for assembly of the region from 124 samples representing 90 species of Asclepias. Reads were mapped back to each individual's consensus and at each position reads differing from the consensus were tallied using a custom perl script. Low frequency polymorphisms existed in all individuals (mean = 5.8%). Most nrDNA positions (91%) were polymorphic in at least one individual, with polymorphic sites being less frequent in subunit regions and loops. Highly polymorphic sites existed in each individual, with highest abundance in the "noncoding" ITS regions. Phylogenetic signal was present in the distribution of intragenomic polymorphisms across the genus. Intragenomic polymorphisms in nrDNA are common in Asclepias, being found at higher frequency than any other study to date. The high and variable frequency of polymorphisms across species highlights concerns that phylogenetic applications of nrDNA may be error-prone. The new analytical approach provided here is applicable to other taxa and other high-copy regions characterized by low coverage genome sequencing (genome skimming).

The interplay between the paracetamol polymorphism and its molecular structures dissolved in supercritical CO2 in contact with the solid phase: In situ vibration spectroscopy and molecular dynamics simulation analysis.

PubMed

Oparin, Roman D; Moreau, Myriam; De Walle, Isabelle; Paolantoni, Marco; Idrissi, Abdenacer; Kiselev, Michael G

2015-09-18

The aim of this paper is to characterize the distribution of paracetamol conformers which are dissolved in a supercritical CO2 phase being in equilibrium with their corresponding crystalline form. The quantum calculations and molecular dynamics simulations were used in order to characterize the structure and analyze the vibration spectra of the paracetamol conformers in vacuum and in a mixture with CO2 at various thermodynamic state parameters (p,T). The metadynamics approach was applied to efficiently sample the various conformers of paracetamol. Furthermore, using in situ IR spectroscopy, the conformers that are dissolved in supercritical CO2 were identified and the evolution of the probability of their presence as a functions of thermodynamic condition was quantified while the change in the crystalline form of paracetamol have been monitored by DSC, micro IR and Raman techniques. The DSC analysis as well as micro IR and Raman spectroscopic studies of the crystalline paracetamol show that the subsequent heating up above the melting temperature of the polymorph I of paracetamol and the cooling down to room temperature in the presence of supercritical CO2 induces the formation of polymorph II. The in situ IR investigation shows that two conformers (Conf. 1 and Conf. 2) are present in the phase of CO2 while conformer 3 (Conf. 3) has a high probability to be present after re-crystallization. Copyright © 2015. Published by Elsevier B.V.

A pragmatic approach for engineering porous mannitol and mechanistic evaluation of particle performance.

PubMed

Al-Khattawi, Ali; Koner, Jasdip; Rue, Peter; Kirby, Dan; Perrie, Yvonne; Rajabi-Siahboomi, Ali; Mohammed, Afzal R

2015-08-01

The importance of mannitol has increased recently as an emerging diluent for orodispersible dosage forms. The study aims to prepare spray dried mannitol retaining high porosity and mechanical strength for the development of orally disintegrating tablets (ODTs). Aqueous feed of d-mannitol (10% w/v) comprising ammonium bicarbonate, NH4HCO3 (5% w/v) as pore former was spray dried at inlet temperature of 110-170°C. Compacts were prepared at 151MPa and characterized for porosity, hardness and disintegration time. Particle morphology and drying mechanisms were studied using thermal (HSM, DSC and TGA) and polymorphic (XRD) methods. Tablet porosity increased from 0.20±0.002 for pure mannitol to 0.53±0.03 using fabricated porous mannitol. Disintegration time dropped by 50-77% from 135±5.29s for pure mannitol to 75.33±2.52-31.67±1.53s for mannitol 110-170°C. Hardness increased by 150% at 110°C (258.67±28.89N) and 30% at 150°C (152.70±10.58N) compared to pure mannitol tablets (104.17±1.70N). Increasing inlet temperature resulted in reducing tablet hardness due to generation of 'micro-sponge'-like particles exhibiting significant elastic recovery. Impact of mannitol polymorphism on plasticity/elasticity cannot be ruled out as a mixture of α and β polymorphs formed upon spray drying. Copyright © 2015 Elsevier B.V. All rights reserved.

A Caenorhabditis elegans Wild Type Defies the Temperature–Size Rule Owing to a Single Nucleotide Polymorphism in tra-3

PubMed Central

Kammenga, Jan E; Doroszuk, Agnieszka; Riksen, Joost A. G; Hazendonk, Esther; Spiridon, Laurentiu; Petrescu, Andrei-Jose; Tijsterman, Marcel; Plasterk, Ronald H. A; Bakker, Jaap

2007-01-01

Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature–size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature–size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature–size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 × CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature–size rule, which has puzzled biologists for decades. PMID:17335351

Electronic Structure of CO2 at High Pressure

NASA Astrophysics Data System (ADS)

Shieh, S. R.; Jarrige, I.; Hiraoka, N.; Cai, Y.

2009-12-01

Carbon dioxide (CO2) is one of the important planetary materials that can be found in the Venus, Earth and Mars. Therefore, the behavior of CO2 under different pressure and temperature conditions is of great importance for understanding the evolution of these planets. Recent studies showed that there are six solid phases and one amorphous phase of CO2 found at various pressure and temperature conditions. This indicates that CO2 may exhibit different forms within planetary interiors. To better understand the behavior of CO2 polymorphs and their interactions with other materials it is necessary to study the electronic structures of CO2 polymorphs. Here we report the electronic structures of CO2-I and -III at high pressure and room temperature. The high-pressure inelastic scattering measurements of CO2 were conducted at beamline 12XU, SPring-8. A monochromatic beam with incident energy about 10 KeV was focused by a pair of KB mirrors to a size of 20 by 30 μm2. The inelastic x-ray scattering photons were collected at about 35 degrees and a solid state Si detector with resolution of about 1.4eV was used. Each spectrum was collected for 8-20 hours. Our results show that a strong pi bond, together with weak sigma bonds of oxygen K-edge were observed in CO2-I and -III phase. For the carbon K-edge of CO2-I, only a single pi bond was observed. This suggests that the molecular solid phase of CO2-I exhibits a gas-like phase instead of a crystal-like phase. Similar results were also observed form CO2-III.

Limited social plasticity in the socially polymorphic sweat bee Lasioglossum calceatum.

PubMed

Davison, P J; Field, J

2018-01-01

Eusociality is characterised by a reproductive division of labour, where some individuals forgo direct reproduction to instead help raise kin. Socially polymorphic sweat bees are ideal models for addressing the mechanisms underlying the transition from solitary living to eusociality, because different individuals in the same species can express either eusocial or solitary behaviour. A key question is whether alternative social phenotypes represent environmentally induced plasticity or predominantly genetic differentiation between populations. In this paper, we focus on the sweat bee Lasioglossum calceatum , in which northern or high-altitude populations are solitary, whereas more southern or low-altitude populations are typically eusocial. To test whether social phenotype responds to local environmental cues, we transplanted adult females from a solitary, northern population, to a southern site where native bees are typically eusocial. Nearly all native nests were eusocial, with foundresses producing small first brood (B1) females that became workers. In contrast, nine out of ten nests initiated by transplanted bees were solitary, producing female offspring that were the same size as the foundress and entered directly into hibernation. Only one of these ten nests became eusocial. Social phenotype was unlikely to be related to temperature experienced by nest foundresses when provisioning B1 offspring, or by B1 emergence time, both previously implicated in social plasticity seen in two other socially polymorphic sweat bees. Our results suggest that social polymorphism in L. calceatum predominantly reflects genetic differentiation between populations, and that plasticity is in the process of being lost by bees in northern populations. Phenotypic plasticity is thought to play a key role in the early stages of the transition from solitary to eusocial behaviour, but may then be lost if environmental conditions become less variable. Socially polymorphic sweat bees exhibit either solitary or eusocial behaviour in different geographic populations, depending on the length of the nesting season. We tested for plasticity in the socially polymorphic sweat bee Lasioglossum calceatum by transplanting nest foundresses from a northern, non-eusocial population to a southern, eusocial population. Plasticity would be detected if transplanted bees exhibited eusocial behaviour. We found that while native bees were eusocial, 90% of transplanted bees and their offspring did not exhibit traits associated with eusociality. Environmental variables such as time of offspring emergence or temperatures experienced by foundresses during provisioning could not explain these differences. Our results suggest that the ability of transplanted bees to express eusociality is being lost, and that social polymorphism predominantly reflects genetic differences between populations.

Skeletal mineralogy of coral recruits under high temperature and pCO2

NASA Astrophysics Data System (ADS)

Foster, T.; Clode, P. L.

2015-08-01

Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility leaves animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore, important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg / Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ∼540 myr. Experimentally reduced Mg / Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals, however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of one-month old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (∼900 μatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be to investigate the combined impact of high pCO2 and reduced Mg / Ca ratio on coral skeletal mineralogy.

Skeletal mineralogy of coral recruits under high temperature and pCO2

NASA Astrophysics Data System (ADS)

Foster, T.; Clode, P. L.

2016-03-01

Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility may leave animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg / Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ˜ 540 Ma. Experimentally reduced Mg / Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals; however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of 1-month-old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (˜ 900 µatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be the investigation of the combined impact of high pCO2 and reduced Mg / Ca ratio on coral skeletal mineralogy.

Polymorphisms in base excision repair genes as colorectal cancer risk factors and modifiers of the effect of diets high in red meat

PubMed Central

Brevik, Asgeir; Joshi, Amit D.; Corral, Román; Onland-Moret, N. Charlotte; Siegmund, Kimberly D.; Le Marchand, Loïc; Baron, John A.; Martinez, Maria Elena; Haile, Robert W.; Ahnen, Dennis J.; Sandler, Robert S.; Lance, Peter; Stern, Mariana C.

2010-01-01

Background A diet high in red meat is an established colorectal cancer (CRC) risk factor. Carcinogens generated during meat cooking have been implicated as causal agents, and can induce oxidative DNA damage, which elicits repair by the base excision repair (BER) pathway. Methods Using a family-based study we investigated the role of polymorphisms in four BER genes (APEX1 Gln51His, Asp148Glu; OGG1 Ser236Cys; PARP Val742Ala; XRCC1 Arg194Trp, Arg280His, Arg399Gln) as potential CRC risk factors and modifiers of the association between high-red meat or poultry diets and CRC risk. We tested for gene-environment interactions using case-only analyses (N = 577) and compared statistically significant results to those obtained using case-unaffected sibling comparisons (N = 307 sibships). Results Carriers of the APEX1 codon 51 Gln/His genotype had a reduced CRC risk compared to carriers of the Gln/Gln genotype (OR 0.15, 95% CI 0.03-0.69, p = 0.015). The association between higher red meat intake (>3 servings/week) and CRC was modified by the PARP Val762Ala SNP (case-only interaction p = 0.026). This SNP also modified the association between higher intake of high-temperature cooked red meat (case-only interaction p = 0.0009). Conclusions We report evidence that the BER pathway PARP gene modifies the association of diets high in red meat cooked at high temperatures with risk of CRC. Impact Our findings suggest a contribution to colorectal carcinogenesis of free radical damage as one of the possible harmful effects of a high-red meat diet. PMID:21037106

Searching the Cambridge Structural Database for polymorphs.

PubMed

van de Streek, Jacco; Motherwell, Sam

2005-10-01

In order to identify all pairs of polymorphs in the Cambridge Structural Database (CSD), a method was devised to automatically compare two crystal structures. The comparison is based on simulated powder diffraction patterns, but with special provisions to deal with differences in unit-cell volumes caused by temperature or pressure. Among the 325,000 crystal structures in the Cambridge Structural Database, 35,000 pairs of crystal structures of the same chemical compound were identified and compared. A total of 7300 pairs of polymorphs were identified, of which 154 previously were unknown.

N-Acetyltransferase 1 Polymorphism and Breast Cancer Risk

DTIC Science & Technology

2011-10-01

reported that cancer risk associated with NAT1*10 is further modulated by exposure to environmental carcinogens found in cigarette smoke, meats cooked...at high temperatures, and the use of hair dye. For example, frequent 7 consumption of red meat in combination with NAT1*10 is associated with an...well- done meat intake, and breast cancer risk. Cancer Epidemiol Biomarkers Prev 8, 233-239. Zhu, Y., and Hein, D.W. (2008). Functional effects of

Anomalous heat transfer in two polymorphs of para-bromobenzophenone

NASA Astrophysics Data System (ADS)

Romantsova, O. O.; Horbatenko, Yu. V.; Krivchikov, A. I.; Korolyuk, O. A.; Vdovichenko, G. A.; Zloba, D. I.; Pyshkin, O. S.

2017-03-01

The thermal conductivity of a polycrystalline sample of monoclinic polymorph of para-bromobenzophenone in the T = 3-320 K temperature range was measured using steady-state linear heat flow. The temperature dependences of thermal conductivity are presented as the sum of two independent contributions: a contribution that corresponds to the thermal conductivity of an orientationally ordered crystal structure, and a new additional thermally activated contribution that manifests itself above 130 K. A comparison is made with the data on the thermal conductivity of a single crystal triclinic polymorph of para-bromobenzophenone. It is established that the contribution corresponding to the thermal conductivity of the orientationally ordered crystal structure depends on the molecular crystal packing, and the characteristic activation energy of the thermal activation contribution, which is caused by the intramolecular vibrations of the C-Br bond, does not depend on the grain size or on the structure of the sample.

Crystal structure of minoxidil at low temperature and polymorph prediction.

PubMed

Martín-Islán, Africa P; Martín-Ramos, Daniel; Sainz-Díaz, C Ignacio

2008-02-01

An experimental and theoretical investigation on crystal forms of the popular and ubiquitous pharmaceutical Minoxidil is presented here. A new crystallization method is presented for Minoxidil (6-(1-piperidinyl)-2,4-pyrimidinediamide 3-oxide) in ethanol-poly(ethylene glycol), yielding crystals with good quality. The crystal structure is determined at low temperature, with a final R value of 0.035, corresponding to space group P2(1) (monoclinic) with cell dimensions a = 9.357(1) A, b = 8.231(1) A, c = 12.931(2) A, and beta = 90.353(4) degrees . Theoretical calculations of the molecular structure of Minoxidil are set forward using empirical force fields and quantum-mechanical methods. A theoretical prediction for Minoxidil crystal structure shows many possible polymorphs. The predicted crystal structures are compared with X-ray experimental data obtained in our laboratory, and the experimental crystal form is found to be one of the lowest energy polymorphs.

An Experiment in Physical Chemistry: Polymorphism and Phase Stability in Acetaminophen (Paracetamol)

ERIC Educational Resources Information Center

Myrick, Michael L.; Baranowski, Megan; Profeta, Luisa T. M.

2010-01-01

Differential scanning calorimetry analyses of two easily prepared polymorphs of acetaminophen (also known as paracetamol) are recorded. The density of the forms can be found in the literature. Rules for heats of transition, heats of fusion, and density, as well as methods for determining the solid-solid transition temperature between the forms,…

Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aboussatar, Mohamed; Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax; Mbarek, Aïcha

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1),more » c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F compounds are reviewed. • IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F.« less

Mechanical and thermodynamic properties of AlX (X = N, P, As) compounds

NASA Astrophysics Data System (ADS)

Xu, Lifang; Bu, Wei

2017-09-01

The Vickers hardness of various AlX (X = N, P, As) compound polymorphs were calculated with the bond resistance model. Thermodynamic properties, such as vibrational entropy, constant volume specific heat and Debye temperatures, were calculated using phonon dispersion relations and phonon density of states (DOS). The calculated values are in good agreement with the previous experimental and theoretical data. For the same structure of AlX (X = N, P, As) compounds, their hardness and Debye temperatures both decrease with the X atomic number. The wurtzite (wz) and zincblende (zb) structures of the same compounds AlX share an almost identical hardness, but have different Debye temperatures. The difference between wz and zb structures increases as the atomic number of X increases. The thermodynamic properties reveal that the constant volume specific heat approaches the Dulong-Petit rule at high temperatures.

The influence of growth environment on the crystallization of nortriptyline hydrochloride, a tricyclic antidepressant

NASA Astrophysics Data System (ADS)

MacCalman, M. L.; Roberts, K. J.; Hendriksen, B. A.

1993-03-01

The preparation of the nortriptyline hydrochloride, an important pharmaceutical product, by crystallization from both alcohol and aqueous solutions is presented. At low temperatures this material shows a higher solubility in absolute alcohol compared to aqueous solutions in a trend which reverses at higher temperatures. Examination of crystals prepared from alcohol solutions reveal essentially a needle-like crystal habit which is in excellent agreement with morphological predictions based on the bulk crystallographic structure. In contrast crystals prepared from aqueous solution at high temperatures reveal a particulate structure dominated by heavily agglomerated crystallites with plate-like morphology. When this material is crystallized at the lower temperatures, where the solubility curve is steep, X-ray and thermal analysis appear to show that crystallization results in a new polymorphic structure associated with a less agglomerated product.

A superhard, quenchable carbon polymorph formed by the room-temperature compression of graphite (Invited)

NASA Astrophysics Data System (ADS)

Wang, Y.; Kiefer, B.; Lee, K. K.

2010-12-01

As one of the revolutionary inventions of the 20th century, synthetic diamond has had a large impact on industry and on scientific research. However, the necessities of high pressures, high temperatures and a metal catalyst during the manufacturing of synthetic diamond make it energy consuming thus limits its availability and use. Here, we report on the synthesis of a superhard non-diamond material resulting from the compression of graphite above ~20 GPa at room temperature without the utilization of metal catalysts. The final product includes a nano-sized phase of carbon that is recoverable at ambient conditions. Furthermore, the ring cracks left on the diamond anvils suggest that the hardness of this post-graphite phase is at least comparable to that of diamond. We use high-resolution synchrotron x-ray diffraction and micro-Raman spectroscopy to monitor the structural transformation in graphite under high pressure and room temperature and find the transition to be sluggish. The possible crystal structure of the new, quenchable phase will be discussed and the time-dependent formation of this superhard post-graphite carbon will be addressed and compared to first-principle predictions.

Synthesis and high (pressure, temperature) stability of ZnTiO3 polymorphs studied by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Bernert, T.; Ruiz-Fuertes, J.; Bayarjargal, L.; Winkler, B.

2015-05-01

The phase-purity of ilmenite-type ZnTiO3 prepared by the ceramic method was investigated in dependence of the conditions during ball milling. The previously proposed addition of 2 ml ethanol to the starting materials led to a significant contamination of the product phase after a subsequent sintering process at 1073 K. However, by omitting ethanol this synthesis route led to a phase-pure sample of ZnTiO3 as confirmed by X-ray powder diffraction and Raman spectroscopy. High-temperature high-pressure experiments gave an ilmenite-type to perovskite-type phase boundary with a slope of dT/dP∼-135 K GPa-1 crossing ambient temperature conditions at ∼ 24 GPa in good agreement with previous calculations. Room-temperature high-pressure Raman spectroscopy experiments have shown the stability of the ilmenite-type phase up to a pressure of at least 38.5 GPa, the highest pressure applied in this study, indicating the presence of a kinetic barrier in this phase transition. The synthesis of ferroelectric LiNbO3-type ZnTiO3 was confirmed by second harmonic generation.

Stability hierarchy between Piracetam forms I, II, and III from experimental pressure-temperature diagrams and topological inferences.

PubMed

Toscani, Siro; Céolin, René; Minassian, Léon Ter; Barrio, Maria; Veglio, Nestor; Tamarit, Josep-Lluis; Louër, Daniel; Rietveld, Ivo B

2016-01-30

The trimorphism of the active pharmaceutical ingredient piracetam is a famous case of polymorphism that has been frequently revisited by many researchers. The phase relationships between forms I, II, and III were ambiguous because they seemed to depend on the heating rate of the DSC and on the history of the samples or they have not been observed at all (equilibrium II-III). In the present paper, piezo-thermal analysis and high-pressure differential thermal analysis have been used to elucidate the positions of the different solid-solid and solid-liquid equilibria. The phase diagram, involving the three solid phases, the liquid phase and the vapor phase, has been constructed. It has been shown that form III is the high-pressure, low-temperature form and the stable form at room temperature. Form II is stable under intermediary conditions and form I is the low pressure, high temperature form, which possesses a stable melting point. The present paper demonstrates the strength of the topological approach based on the Clapeyron equation and the alternation rule when combined with high-pressure measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

Intragenomic polymorphisms among high-copy loci: a genus-wide study of nuclear ribosomal DNA in Asclepias (Apocynaceae)

PubMed Central

Straub, Shannon C.K.; Fishbein, Mark; Liston, Aaron

2015-01-01

Despite knowledge that concerted evolution of high-copy loci is often imperfect, studies that investigate the extent of intragenomic polymorphisms and comparisons across a large number of species are rarely made. We present a bioinformatic pipeline for characterizing polymorphisms within an individual among copies of a high-copy locus. Results are presented for nuclear ribosomal DNA (nrDNA) across the milkweed genus, Asclepias. The 18S-26S portion of the nrDNA cistron of Asclepias syriaca served as a reference for assembly of the region from 124 samples representing 90 species of Asclepias. Reads were mapped back to each individual’s consensus and at each position reads differing from the consensus were tallied using a custom perl script. Low frequency polymorphisms existed in all individuals (mean = 5.8%). Most nrDNA positions (91%) were polymorphic in at least one individual, with polymorphic sites being less frequent in subunit regions and loops. Highly polymorphic sites existed in each individual, with highest abundance in the “noncoding” ITS regions. Phylogenetic signal was present in the distribution of intragenomic polymorphisms across the genus. Intragenomic polymorphisms in nrDNA are common in Asclepias, being found at higher frequency than any other study to date. The high and variable frequency of polymorphisms across species highlights concerns that phylogenetic applications of nrDNA may be error-prone. The new analytical approach provided here is applicable to other taxa and other high-copy regions characterized by low coverage genome sequencing (genome skimming). PMID:25653903

Control of temperature and aqueous Mg2+/Ca2+ ratio on the (trans-)formation of ikaite

NASA Astrophysics Data System (ADS)

Purgstaller, B.; Dietzel, M.; Baldermann, A.; Mavromatis, V.

2017-11-01

The calcium carbonate hexahydrate mineral ikaite (CaCO3 ṡ 6 H2O) has been documented in aquatic environments at near-freezing temperatures. An increase of the prevailing temperature in the depositional environment, results in the transformation of natural ikaite into less soluble calcium carbonate phases occasionally leaving calcite pseudomorphs in the sediments, which are considered as an indicator for primary cold water temperatures. Detailed understanding on the physicochemical parameters controlling ikaite (trans-)formation however, such as temperature and reactive solution chemical composition, are still under debate. In order to study the formation of ikaite, we conducted precipitation experiments under controlled physicochemical conditions (pH = 8.3 ± 0.1; T = 6, 12, and 18 ± 0.1 °C) at defined aqueous molar Mg/Ca ratios. The transformation of ikaite into anhydrous calcium carbonate polymorphs was investigated in solution and at air exposure. The obtained results reveal the formation of ikaite at temperatures up to 12 °C, whereas Mg-rich amorphous calcium carbonate precipitated at 18 °C. In contact with the reactive solution ikaite transformed into aragonite at aqueous molar Mg2+/Ca2+ ratios of ≥14. In contrast, ikaite separated from the Mg-rich solution and exposed to air transformed in all cases into calcite/vaterite. The herein obtained temperature limit of ≤12 for ikaite formation is significantly higher than formerly expected and most probably caused by (i) the high saturation degree of the solution with respect to ikaite and (ii) the slow dehydration of the aqueous Ca2+ ion at low temperatures. This result questions the suitability of calcite pseudomorphs (i.e. glendonites) as a proxy for near-freezing temperatures. Moreover, our findings show that the CaCO3 polymorph formed from ikaite is strongly controlled by the physicochemical conditions, such as aqueous molar Mg2+/Ca2+ ratio of the reactive fluid and H2O availability throughout the transformation process.

Bulk and Interface Thermodynamics of Calcia-, and Yttria-doped Zirconia Ceramics: Nanograined Phase Stability

NASA Astrophysics Data System (ADS)

Drazin, John Walter

Calcia-, and yttria- doped zirconia powders and samples are essential systems in academia and industry due to their observed bulk polymorphism. Pure zirconia manifests as Baddeleyite, a monoclinic structured mineral with 7-fold coordination. This bulk form of zirconia has little application due to its asymmetry. Therefore dopants are added to the grain in-order to induce phase transitions to either a tetragonal or cubic polymorph with the incorporation of oxygen vacancies due to the dopant charge mis-match with the zirconia matrix. The cubic polymorph has cubic symmetry such that these samples see applications in solid oxide fuel cells (SOFCs) due to the high oxygen vacancy concentrations and high ionic mobility at elevated temperatures. The tetragonal polymorph has slight asymmetry in the c-axis compared to the a-axis such that the tetragonal samples have increased fracture toughness due to an impact induced phase transformation to a cubic structure. These ceramic systems have been extensively studied in academia and used in various industries, but with the advent of nanotechnology one can wonder whether smaller grain samples will see improved characteristics similar to their bulk grain counterparts. However, there is a lack of data and knowledge of these systems in the nano grained region which provides us with an opportunity to advance the theory in these systems. The polymorphism seen in the bulk grains samples is also seen in the nano-grained samples, but at slightly distinct dopant concentrations. The current theory hypothesizes that a surface excess, gamma (J/m 2), can be added to the Gibbs Free energy equation to account for the additional free energy of the nano-grain atoms. However, these surface energies have been difficult to measure and therefore thermodynamic data on these nano-grained samples have been sparse. Therefore, in this work, I will use a well established water adsorption microcalorimetry apparatus to measure the water coverage isotherms while simultaneously collecting the energetic contribution of the adsorbing water vapor. With this data and apparatus, I have derived a 2nd order differential equation that relates the surface energy to the measured quantities such that I collected surfaces energies for over 35 specimens in the calcia-zirconia and yttria-zirconia systems for the first time. From the results, it was found that the monoclinic polymorph had the largest surface energy in the range of 1.9 - 2.1 ( J/m2) while the tetragonal surface energies were roughly 1.4 - 1.6 (J/m2), the cubic surface energies were roughly 0.8 - 1.0 (J/m2), and the amorphous surface energies were the smallest at roughly 0.7 - 0.8 (J/m 2). With the measured surface energy data, collected for the first time, we can create a nano-grain phase diagram similar to a bulk phase diagram that shows the stable polymorph as a function of dopant concentration and grain size using the bulk enthalpy data collected from high temperature oxide melt drop solution calorimetry. The phase diagrams show that pure zirconia will transform into tetragonal and cubic polymorphs from the monoclinic one at 7 and 5 nm respectively which confirms the experimental observations. The results are powerful predictive tools successfully applied in the nCZ and nYZ systems to a high degree of accuracy and adds a new development to conventional bulk phase diagrams. These diagrams should be the basis for nanotechnological efforts in nCZ and nYZ based systems, and suggest similar efforts are needed in other nano systems to pursue an in depth understanding and optimization of nanomaterials. After working on the theoretical aspects of phase stability, the focus of the research will shift to producing dense samples to measure observable quantities such as oxygen conduction and mechanical hardness. However, producing said samples with the nanocrystalline grain sizes has also been challenging as conventional sintering requires high temperatures which, as a consequence, induces grain growth of the samples limiting the minimum grain size of the samples. Therefore, in this work, we have developed a Pressure Assisted Rapid Sintering Technique (PARS) that uses high currents to Joule heat the samples to moderate temperatures (650-900 °C) for short durations (5-10 min) under large compressive pressures (600-2200 MPa). With this new technique, atomic level grain sizes (sub-10nm) can be easily achieved at high relative densities (>98 %). Using the PARS setup, multiple 3nYZ samples were produced with varied grain sizes down to 9 nm and as large as 5mum. The mechanical hardness of these samples were tested using a Vicker's microhardness indentation apparatus. The hardness of the "bulk" grains was roughly 12.9 GPa while the smallest grain size pellet had a hardness approaching 15 GPa. All of the 3nYZ pellets had a higher hardness with diminishing grain size, thereby extending the Hall-Petch relationship to 9 nm in the 3YZ system. This is an amazing and unprecedented result to date. After producing the extreme nano-grained samples (15nCZ and 17.5nYSZ), they were tested for inter- and intragranular oxygen ion conduction as well. The results showed that the smaller grained samples have increased levels of oxygen ion conduction from both inter- and intragranular diffusion regardless of the operating temperatures. In addition, it was seen that the activation energies for both modes of oxygen ion diffusion were lowered for the nCZ system while a plateaued effect was seen in the nYZ system. A new theoretical formulation was proposed to explain the trends such that there are two modifiable parameters to exploit; activation energy and grain size. With the lowering of the grain size, the number of interconnected grain boundaries would increase dramatically allowing for more efficient travel around and through the grains. The activation energy can be lowered by modifying the chemistry of the grain boundary by specifically choosing larger dopants with a positive enthalpy of segregation such the concentration of the dopants on the grain boundary would increase, spacing the unattached bonds further apart and reducing their number. Therefore, one can use an engineered nanograined SOFC to decrease the operating temperature of the device without altering the output power density; significantly improving safety and economics.

Albite dissociation reaction in the Northwest Africa 8275 shocked LL chondrite and implications for its impact history

NASA Astrophysics Data System (ADS)

Miyahara, Masaaki; Ohtani, Eiji; Yamaguchi, Akira

2017-11-01

An impact event recorded in the Northwest Africa (NWA) 8275 LL7 ordinary chondrite was investigated based on high-pressure mineralogy of pervasive shock-melt veins present in the rock. NWA 8275 consists of olivine, low-Ca pyroxene, plagioclase (albite-oligoclase composition), and minor high-Ca pyroxene, K-feldspar, phosphate minerals, metallic Fe-Ni and iron sulfide. Plagioclase and K-feldspar grains near the shock-melt veins have become amorphous, although no high-pressure polymorphs of olivine and pyroxene were identified in or adjacent the shock-melt veins. Raman spectroscopy and focused ion beam (FIB)-assisted transmission electron microscopy (TEM) observations reveal that plagioclase entrained around the center portion of the shock-melt veins has dissociated into a jadeite + coesite assemblage. Alternately stacked jadeite and coesite crystals occur in the original plagioclase. On approaching the host rock/shock-melt vein, only jadeite is present. Based on the high-pressure polymorph assemblage, the shock pressure and temperature conditions recorded in the shock-melt veins are ∼3-12 GPa and ∼1973-2373 K, respectively. Following a Rankine-Hugoniot relationship, the impact velocity was at least ∼0.45-1.54 km/s. The duration of high-pressure and high-temperature (HPHT) conditions required for the albite dissociation reaction is estimated a maximum of ∼4-5 s using the phase transition rate of albite, implying that a body of up to ∼9-12 km across collided with the parent body of NWA 8275. The coexistence of jadeite and coesite, the latter of which rarely accompanies jadeite in shocked ordinary chondrites, as a dissociation product of albite requires relatively long duration HPHT conditions. Thus, the impact event recorded in NWA 8275 was likely caused by a larger-than-typical projectile.

Electric-field-dependent phase volume fractions and enhanced piezoelectricity near the polymorphic phase boundary of (K0.5Na0.5)1-xLixNbO3 textured ceramics

NASA Astrophysics Data System (ADS)

Ge, Wenwei; Li, Jiefang; Viehland, D.; Chang, Yunfei; Messing, Gary L.

2011-06-01

The structure, ferroelectric and piezoelectric properties of <001> textured (K0.5Na0.5)0.98Li0.02NbO3 ceramics were investigated as a function of temperature and dc bias E. X-ray diffraction revealed an orthorhombic (O) → tetragonal (T) polymorphic phase boundary (PPB). Phase coexistence was found near the PPB over a 30 °C temperature range, where the relative phase volume fractions changed with temperature. Furthermore, increasing E applied along the <001> texture direction resulted in a notable increase in the volume fraction of the T phase at the expense of the O phase, effectively shifting the O → T boundary to lower temperature. An enhancement in the piezoelectric properties was found to accompany this increase in the T volume fraction.

Inverse Correlation of Population Similarity and Introduction Date for Invasive Ascidians

PubMed Central

Silva, Nathan; Smith, William C.

2008-01-01

The genomes of many marine invertebrates, including the purple sea urchin and the solitary ascidians Ciona intestinalis and Ciona savignyi, show exceptionally high levels of heterozygosity, implying that these populations are highly polymorphic. Analysis of the C. savignyi genome found little evidence to support an elevated mutation rate, but rather points to a large population size contributing to the polymorphism level. In the present study, the relative genetic polymorphism levels in sampled populations of ten different ascidian species were determined using a similarity index generated by AFLP analysis. The goal was to determine the range of polymorphism within the populations of different species, and to uncover factors that may contribute to the high level of polymorphism. We observe that, surprisingly, the levels of polymorphism within these species show a negative correlation with the reported age of invasive populations, and that closely related species show substantially different levels of genetic polymorphism. These findings show exceptions to the assumptions that invasive species start with a low level of genetic polymorphism that increases over time and that closely related species have similar levels of genetic polymorphism. PMID:18575620

Experimental and theoretical investigation of the elastic moduli of silicate glasses and crystals

NASA Astrophysics Data System (ADS)

Philipps, Katharina; Stoffel, Ralf Peter; Dronskowski, Richard; Conradt, Reinhard

2017-02-01

A combined quantum-mechanical and thermodynamic approach to the mechanical properties of multicomponent silicate glasses is presented. Quantum chemical calculations based on density-functional theory (DFT) on various silicate systems were performed to explore the crystalline polymorphs existing for a given chemical composition. These calculations reproduced the properties of known polymorphs even in systems with extensive polymorphism, like MgSiO3. Properties resting on the atomic and electronic structure, i.e., molar volumes (densities) and bulk moduli were predicted correctly. The theoretical data (molar equilibrium volumes, bulk moduli) were then used to complement the available experimental data. In a phenomenological evaluation, experimental data of bulk moduli, a macroscopic property resting on phononic structure, were found to linearly scale with the ratios of atomic space demand to actual molar volume in a universal way. Silicates ranging from high-pressure polymorphs to glasses were represented by a single master line. This suggests that above the Debye limit (in practice: above room temperature), the elastic waves probe the short range order coordination polyhedra and their next-neighbor linkage only, while the presence or absence of an extended translational symmetry is irrelevant. As a result, glasses can be treated - with respect to the properties investigated - as commensurable members of polymorphic series. Binary glasses fit the very same line as their one-component end-members, again both in the crystalline and glassy state. Finally, it is shown that the macroscopic properties of multicomponent glasses also are linear superpositions of the properties of their constitutional phases (as determined from phase diagrams or by thermochemical calculations) taken in their respective glassy states. This is verified experimentally for heat capacities and Young’s moduli of industrial glass compositions. It can be concluded, that the combined quantum mechanical and thermochemical approach is a truly quantitative approach for the design of glasses with desired mechanical properties, e.g., for the development of high-modulus glasses.

Probing of Fast Chemical Dynamics at High Pressures and Temperatures using Pulsed Laser Techniques

DTIC Science & Technology

2014-12-17

Alexander F. Goncharov, N . Subramanian, T. R. Ravindran, Maddury Somayazulu, Vitali B. Prakapenka, Russell J. Hemley. Polymorphism of dense, hot oxygen...2011): 0. doi: 10.1021/jp204642b Alexander F. Goncharov, N . Subramanian, T. R. Ravindran, Maddury Somayazulu, Vitali B. Prakapenka, Russell J...study the evolution and dynamics of planets and stars. (a) Papers published in peer-reviewed journals ( N /A for none) Enter List of papers submitted or

Preferential Stereocomplex Crystallization in Enantiomeric Blends of Cellulose Acetate-g-Poly(lactic acid)s with Comblike Topology.

PubMed

Bao, Jianna; Han, Lili; Shan, Guorong; Bao, Yongzhong; Pan, Pengju

2015-10-01

Although stereocomplex (sc) crystallization is highly effective for improving the thermal resistance of poly(lactic acid) (PLA), it is much less predominant than homocrystallization in high-molecular-weight (HMW) poly(l-lactic acid)/ poly(d-lactic acid) (PLLA/PDLA) racemic blends. In this contribution, the sc crystallization of HMW PLLA/PDLA racemic blends was facilitated by using comblike PLAs with cellulose acetate as the backbone. Competing crystallization kinetics, polymorphic crystalline structure, and structural transition of comblike PLLA/PDLA blends with a wide range of MWs were investigated and compared with the corresponding linear/comblike and linear blends. The HMW comblike blend is preferentially crystallized in sc polymorphs and exhibits a faster crystallization rate than does the corresponding linear blend. The sc crystallites are predominantly formed in nonisothermal cold crystallization and isothermal crystallization at temperatures above 120 °C for the comblike blends. Except for the facilitated sc formation in primary crystallization, synchrotron radiation WAXD analysis indicates that the presence of a comblike component also facilitates the transition or recrystallization from homocrystallite (hc) to sc crystallite upon heating. Preferential sc formation of comblike blends is probably attributable to the favorable interdigitation between enantiomeric branches and the increased mobility of polymer segments. After crystallization under the same temperature, the comblike blends, which mainly contain sc crystallites, show smaller long periods and thinner crystalline lamellae than do the corresponding PLLA with homocrystalline structures.

Phenomenology of Polymorphism, III: p, TDiagram and Stability of Piracetam Polymorphs

NASA Astrophysics Data System (ADS)

Céolin, R.; Agafonov, V.; Louër, D.; Dzyabchenko, V. A.; Toscani, S.; Cense, J. M.

1996-02-01

The nootropic drug Piracetam is known to crystallize in three phases. In order to obtain their stability hierarchy from sublimation pressure inequalities, the drawing of a topologicalp,Tdiagram was attempted. For such a purpose and also for quality control, crystallographic and thermodynamic data were required. Powder X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) were used. Molecular energy calculations were performed. Phase I melts at 426 K (ΔfusH(I) = +180 J·g-1). Phase II transforms into Phase I at 399 K (Δ(II→I)H= +24 J·g-1). Phase III transforms into phase I at 392 K (Δ(III→I)H= +28 J·g-1) or melts at 412 K (ΔfusH(III) = +210 J·g-1). Thep,Tdiagram shows that phase I is stable at higher temperature and phase II at lower temperature, like phase III, which is stable under high pressure. At room temperature, phase II is the more stable form, and phase I the less stable one. This agrees with the spontaneous I → II transformation observed at 298 K within a few hours, and with lattice energies, calculated previously. Molecular energy calculations and crystal structure comparison show how intermolecular hydrogen bonds and H-bonded dimers, in phases II and III, may stabilize conformations higher in energy than those of the isolated molecule and of phase I.

Coordination polymer flexibility leads to polymorphism and enables a crystalline solid-vapour reaction: a multi-technique mechanistic study.

PubMed

Vitórica-Yrezábal, Iñigo J; Libri, Stefano; Loader, Jason R; Mínguez Espallargas, Guillermo; Hippler, Michael; Fletcher, Ashleigh J; Thompson, Stephen P; Warren, John E; Musumeci, Daniele; Ward, Michael D; Brammer, Lee

2015-06-08

Despite an absence of conventional porosity, the 1D coordination polymer [Ag4 (O2 C(CF2 )2 CF3 )4 (TMP)3 ] (1; TMP=tetramethylpyrazine) can absorb small alcohols from the vapour phase, which insert into AgO bonds to yield coordination polymers [Ag4 (O2 C(CF2 )2 CF3 )4 (TMP)3 (ROH)2 ] (1-ROH; R=Me, Et, iPr). The reactions are reversible single-crystal-to-single-crystal transformations. Vapour-solid equilibria have been examined by gas-phase IR spectroscopy (K=5.68(9)×10(-5) (MeOH), 9.5(3)×10(-6) (EtOH), 6.14(5)×10(-5) (iPrOH) at 295 K, 1 bar). Thermal analyses (TGA, DSC) have enabled quantitative comparison of two-step reactions 1-ROH→1→2, in which 2 is the 2D coordination polymer [Ag4 (O2 C(CF2 )2 CF3 )4 (TMP)2 ] formed by loss of TMP ligands exclusively from singly-bridging sites. Four polymorphic forms of 1 (1-A(LT) , 1-A(HT) , 1-B(LT) and 1-B(HT) ; HT=high temperature, LT=low temperature) have been identified crystallographically. In situ powder X-ray diffraction (PXRD) studies of the 1-ROH→1→2 transformations indicate the role of the HT polymorphs in these reactions. The structural relationship between polymorphs, involving changes in conformation of perfluoroalkyl chains and a change in orientation of entire polymers (A versus B forms), suggests a mechanism for the observed reactions and a pathway for guest transport within the fluorous layers. Consistent with this pathway, optical microscopy and AFM studies on single crystals of 1-MeOH/1-A(HT) show that cracks parallel to the layers of interdigitated perfluoroalkyl chains develop during the MeOH release/uptake process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heat-transfer resistance at solid-liquid interfaces: a tool for the detection of single-nucleotide polymorphisms in DNA.

PubMed

van Grinsven, Bart; Vanden Bon, Natalie; Strauven, Hannelore; Grieten, Lars; Murib, Mohammed; Monroy, Kathia L Jiménez; Janssens, Stoffel D; Haenen, Ken; Schöning, Michael J; Vermeeren, Veronique; Ameloot, Marcel; Michiels, Luc; Thoelen, Ronald; De Ceuninck, Ward; Wagner, Patrick

2012-03-27

In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA. © 2012 American Chemical Society

Exploring the Phase Diagram SiO2-CO2 at High Pressures and Temperatures

NASA Astrophysics Data System (ADS)

Kavner, A.

2015-12-01

CO2 is an important volatile system relevant for planetary sciences and fundamental chemistry. Molecular CO2 has doubly bonded O=C=O units but high pressure-high temperature (HP-HT) studies have recently shown its transformation into a three-dimensional network of corner-linked [CO4] units analogous to the silica mineral polymorphs, through intermediate non-molecular phases. Here, we report P-V-T data on CO2-IV ice from time-of-flight neutron diffraction experiments, which allow determining the compressibility and thermal expansivity of this intermediate molecular-to-non-molecular phase.1 Aditionally, we have explored the SiO2-CO2 phase diagram and the potential formation of silicon carbonate compounds. New data obtained by laser-heating diamond-anvil experiments in CO2-filled microporous silica polymorphs will be shown. In particular, these HP-HT experiments explore the existence of potential CO2/SiO2 compounds with tetrahedrally-coordinated C/Si atoms by oxygens, which are predicted to be stable (or metastable) by state-of-the-art ab initio simulations.2,3 These theoretical predictions were supported by a recent study that reports the formation of a cristobalite-type Si0.4C0.6O2 solid solution at high-pressures and temperatures, which can be retained as a metastable solid down to ambient conditions.4 Entirely new families of structures could exist based on [CO4]4- units in various degrees of polymerisation, giving rise to a range of chain, sheet and framework solids like those found in silicate chemistry. References[1] S. Palaich et al., Am. Mineral. Submitted (2015) [2] A. Morales-Garcia et al., Theor. Chem. Acc. 132, 1308 (2013) [3] R. Zhou et al., Phys. Rev. X, 4, 011030 (2014) [4] M. Santoro et al. Nature Commun. 5, 3761 (2014)

Immune and stress responses in oysters with insights on adaptation.

PubMed

Guo, Ximing; He, Yan; Zhang, Linlin; Lelong, Christophe; Jouaux, Aude

2015-09-01

Oysters are representative bivalve molluscs that are widely distributed in world oceans. As successful colonizers of estuaries and intertidal zones, oysters are remarkably resilient against harsh environmental conditions including wide fluctuations in temperature and salinity as well as prolonged air exposure. Oysters have no adaptive immunity but can thrive in microbe-rich estuaries as filter-feeders. These unique adaptations make oysters interesting models to study the evolution of host-defense systems. Recent advances in genomic studies including sequencing of the oyster genome have provided insights into oyster's immune and stress responses underlying their amazing resilience. Studies show that the oyster genomes are highly polymorphic and complex, which may be key to their resilience. The oyster genome has a large gene repertoire that is enriched for immune and stress response genes. Thousands of genes are involved in oyster's immune and stress responses, through complex interactions, with many gene families expanded showing high sequence, structural and functional diversity. The high diversity of immune receptors and effectors may provide oysters with enhanced specificity in immune recognition and response to cope with diverse pathogens in the absence of adaptive immunity. Some members of expanded immune gene families have diverged to function at different temperatures and salinities or assumed new roles in abiotic stress response. Most canonical innate immunity pathways are conserved in oysters and supported by a large number of diverse and often novel genes. The great diversity in immune and stress response genes exhibited by expanded gene families as well as high sequence and structural polymorphisms may be central to oyster's adaptation to highly stressful and widely changing environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chromium incorporation into TiO{sub 2} at high pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escudero, Alberto, E-mail: aescudero@icmse.csic.es; Langenhorst, Falko; Institut fuer Geowissenschaften, Friedrich-Schiller-Universitaet Jena, Carl-Zeiss-Promenade 10, D-07745 Jena

2012-06-15

Chromium incorporation into TiO{sub 2} up to 3 GPa at 1300 Degree-Sign C and 900 Degree-Sign C has been studied by XRD as well as TEM. A CaCl{sub 2} type TiO{sub 2} polymorph has been observed in the quenched samples from high pressure. Two different mechanisms of solubility occur in the recovered samples. Chromium replaces titanium on normal octahedral sites but it also occupies interstitial octahedral sites, especially in the samples recovered from higher pressures. Interstitial chromium is responsible for an orthorhombic distortion of the TiO{sub 2} rutile structure in the quenched samples and gives rise to a (1 1more » 0) twinned CaCl{sub 2}-structured polymorph. This phase is very likely the result of temperature quench at high pressure. The formation of this phase is directly related to the chromium content of the TiO{sub 2} grains. Chromium solubility in TiO{sub 2} increases with increasing the synthesis pressure. TiO{sub 2} is able to accommodate up to 15.3 wt% Cr{sub 2}O{sub 3} at 3 GPa and 1300 Degree-Sign C, compared to 5.7 wt% at atmospheric pressure at the same temperature. - Graphical abstract: Microstructure consisting of twins domains of recovered Cr-doped CaCl{sub 2} type TiO{sub 2} grains synthesised at high pressure. Highlights: Black-Right-Pointing-Pointer Chromium solubility in TiO{sub 2} increases at high pressure. Black-Right-Pointing-Pointer Chromium occupies substitutional and interstitial positions in the rutile structure. Black-Right-Pointing-Pointer Interstitial chromium causes a decrease of the rutile symmetry. Black-Right-Pointing-Pointer An orthorhombic CaCl{sub 2} type structure is observed in the quenched samples.« less

Polymorphism in molecular solids: an extraordinary system of red, orange, and yellow crystals.

PubMed

Yu, Lian

2010-09-21

Diamond and graphite are polymorphs of each other: they have the same composition but different structures and properties. Many other substances exhibit polymorphism: inorganic and organic, natural and manmade. Polymorphs are encountered in studies of crystallization, phase transition, materials synthesis, and biomineralization and in the manufacture of specialty chemicals. Polymorphs can provide valuable insights into crystal packing and structure-property relationships. 5-Methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile, known as ROY for its red, orange, and yellow crystals, has seven polymorphs with solved structures, the largest number in the Cambridge Structural Database. First synthesized by medicinal chemists, ROY has attracted attention from solid-state chemists because it demonstrates the remarkable diversity possible in organic solids. Many structures of ROY polymorphs and their thermodynamic properties are known, making ROY an important model system for testing computational models. Though not the most polymorphic substance on record, ROY is extraordinary in that many of its polymorphs can crystallize simultaneously from the same liquid and are kinetically stable under the same conditions. Studies of ROY polymorphs have revealed a new crystallization mechanism that invalidates the common view that nucleation defines the polymorph of crystallization. A slow-nucleating polymorph can still dominate the product if it grows rapidly and nucleates on another polymorph. Studies of ROY have also helped understand a new, surprisingly fast mode of crystal growth in organic liquids cooled to the glass transition temperature. This growth mode exists only for those polymorphs that have more isotropic, and perhaps more liquid-like, packing. The rich polymorphism of ROY results from a combination of favorable thermodynamics and kinetics. Not only must there be many polymorphs of comparable energies or free energies, many polymorphs must be kinetically stable and crystallize at comparable rates to be observed. This system demonstrates the unique insights that polymorphism provides into solid-state structures and properties, as well as the inadequacy of our current understanding of the phenomenon. Despite many studies of ROY, it is still impossible to predict the next molecule that is equally or more polymorphic. ROY is a lucky gift from medicinal chemists.

New Polymorph of Fe3O4 Stable at Core-Mantle Boundary Conditions

NASA Astrophysics Data System (ADS)

Greenberg, E.; Prakapenka, V. B.

2017-12-01

Magnetite Fe3O4 (and its high-pressure polymorphs) is one of the most studied iron bearing minerals. One reason for the interest in magnetite is that it contains both Fe2+ and Fe3+, which is especially important for understanding the physical and chemical properties of Earth's deep interior. Early studies on magnetite debated the nature of the structural phase transition at 35 GPa [1-4]. This high-pressure structure was shown to be of the CaTi2O4-type [5], but with Fe3+ occupying multiple sites. Furthermore, at pressures above 65 GPa a second structural transition to a Pmma space group was shown to take place [5], similar to that in Fe3-xTixO4 solid solution [6]. Other studies have focused on the P-T stability of Fe3O4. Early studies by Lazor et al. [7] predicted that Fe3O4 might disproportionate into FeO and h-Fe2O3 at 50 GPa. Other studies suggested that the high-pressure phase should be stable up to 100 GPa [3]. A more recent experimental study by Ricolleau and Fei [8] revealed that Fe3O4 is stable at least up to 103 GPa. Thus far, structural studies of Fe3O4 have been limited to pressures below 105 GPa. We have studied Fe3O4 up to pressures of 175 GPa and temperatures above 4000K, using diamond anvil cells in combination with synchrotron x-ray diffraction and an online pulsed laser-heating system to study the stability of Fe3O4 at relevant pressure-temperature conditions. Our results show that Fe3O4 is stable up to at least 176 GPa and 4200 K. We have discovered a new polymorph of Fe3O4 at these high P-T conditions. This new phase is stable in the pressure range of at least 100

Polymorphism of a new Mannich base - [-4-methyl-2-((4-(4-nitrophenyl)piperazin-1-yl)methyl)phenol

NASA Astrophysics Data System (ADS)

Ayeni, Ayowole O.; Watkins, Gareth M.; Hosten, Eric C.

2018-05-01

Two polymorphs (forms I and II) of a new Mannich base 4-methyl-2-((4-(4-nitrophenyl)piperazin-1-yl)methyl)phenol have been isolated and characterized by single crystal and powder (experimental and theoretical) X-ray diffraction, thermal analysis (differential scanning calorimetry), Fourier transform infrared spectroscopy. 1H and 13C nuclear magnetic resonance spectroscopy was employed in characterising the new Mannich base. Single crystal X-ray diffraction revealed that the two polymorphs contain different conformers of the Mannich base whose hydrogen bonding schemes and packing arrangements in their respective crystals are different. Thermal analysis led to the conclusion that the two polymorphs are enantiotropically related, with a transition temperature of 138.5 °C.

Solid solubility of Yb 2Si 2O 7 in β-, γ- and δ-Y 2Si 2O 7

NASA Astrophysics Data System (ADS)

Fernández-Carrión, A. J.; Alba, M. D.; Escudero, A.; Becerro, A. I.

2011-07-01

This paper examines the structural changes with temperature and composition in the Yb 2Si 2O 7-Y 2Si 2O 7 system; members of this system are expected to form in the intergranular region of Si 3N 4 and SiC structural ceramics when sintered with the aid of Yb 2O 3 and Y 2O 3 mixtures. A set of different compositions have been synthesised using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1650 °C during different times. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of Yb 2Si 2O 7 in β-Y 2Si 2O 7 and γ-Y 2Si 2O 7. Although Yb 2Si 2O 7 shows a unique stable polymorph (β), Yb 3+ is able to replace Y 3+ in γ-Y 2Si 2O 7 and δ-Y 2Si 2O 7 at high temperatures and low Yb contents. IR results confirm the total solid solubility in the system and suggest a constant SiOSi angle of 180° in the Si 2O 7 unit across the system. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β- RE2Si 2O 7 polymorph, with γ- RE2Si 2O 7 and δ- RE2Si 2O 7 showing reduced stability fields. The diagram is in accordance with Felsche's diagram if average ionic radii are assumed for the members of the solid solution at any temperature, as long as the β-γ phase boundary is slightly shifted towards higher radii.

Characterization of Coconut Oil Fractions Obtained from Solvent Fractionation Using Acetone.

PubMed

Sonwai, Sopark; Rungprasertphol, Poonyawee; Nantipipat, Nantinee; Tungvongcharoan, Satinee; Laiyangkoon, Nantikan

2017-09-01

This work was aimed to study the solvent fraction of coconut oil (CNO). The fatty acid and triacylglycerol compositions, solid fat content (SFC) and the crystallization properties of CNO and its solid and liquid fractions obtained from fractionation at different conditions were investigated using various techniques. CNO was dissolved in acetone (1:1 w/v) and left to crystallize isothermally at 10°C for 0.5, 1 and 2 h and at 12°C for 2, 3 and 6 h. The solid fractions contained significantly lower contents of saturated fatty acids of ≤ 10 carbon atoms but considerably higher contents of saturated fatty acids with > 12 carbon atoms with respect to those of CNO and the liquid fractions. They also contained higher contents of high-melting triacylglycerol species with carbon number ≥ 38. Because of this, the DSC crystallization onset temperatures and the crystallization peak temperatures of the solid fractions were higher than CNO and the liquid fractions. The SFC values of the solid fractions were significantly higher than CNO at all measuring temperatures before reaching 0% just below the body temperature with the fraction obtained at 12°C for 2 h exhibiting the highest SFC. On the contrary, the SFC values of the liquid fractions were lower than CNO. The crystallization duration exhibited strong influence on the solid fractions. There was no effect on the crystal polymorphic structure possibly because CNO has β'-2 as a stable polymorph. The enhanced SFC of the solid fractions would allow them to find use in food applications where a specific melting temperature is desired such as sophisticated confectionery fats, and the decreased SFC of the liquid fractions would provide them with a higher cold stability which would be useful during extended storage time.

Flux-mediated syntheses, structural characterization and low-temperature polymorphism of the p-type semiconductor Cu2Ta4O11

NASA Astrophysics Data System (ADS)

King, Nacole; Sullivan, Ian; Watkins-Curry, Pilanda; Chan, Julia Y.; Maggard, Paul A.

2016-04-01

A new low-temperature polymorph of the copper(I)-tantalate, α-Cu2Ta4O11, has been synthesized in a molten CuCl-flux reaction at 665 °C for 1 h and characterized by powder X-ray diffraction Rietveld refinements (space group Cc (#9), a=10.734(1) Å, b = 6.2506(3) Å, c=12.887(1) Å, β = 106.070(4)°). The α-Cu2Ta4O11 phase is a lower-symmetry monoclinic polymorph of the rhombohedral Cu2Ta4O11 structure (i.e., β-Cu2Ta4O11 space group R 3 ̅ c (#167), a = 6.2190(2) Å, c=37.107(1) Å), and related crystallographically by ahex=amono/√3, bhex=bmono, and chex=3cmonosinβmono. Its structure is similar to the rhombohedral β-Cu2Ta4O11 and is composed of single layers of highly-distorted and edge-shared TaO7 and TaO6 polyhedra alternating with layers of nearly linearly-coordinated Cu(I) cations and isolated TaO6 octahedra. Temperature dependent powder X-ray diffraction data show the α-Cu2Ta4O11 phase is relatively stable under vacuum at 223 K and 298 K, but reversibly transforms to β-Cu2Ta4O11 by at least 523 K and higher temperatures. The symmetry-lowering distortions from β-Cu2Ta4O11 to α-Cu2Ta4O11 arise from the out-of-center displacements of the Ta 5d0 cations in the TaO7 pentagonal bipyramids. The UV-vis diffuse reflectance spectrum of the monoclinic α-Cu2Ta4O11 shows an indirect bandgap transition of ∼2.6 eV, with the higher-energy direct transitions starting at ∼2.7 eV. Photoelectrochemical measurements on polycrystalline films of α-Cu2Ta4O11 show strong cathodic photocurrents of ∼1.5 mA/cm2 under AM 1.5 G solar irradiation.

Variability in response to nicotine in the LSxSS RI strains: potential role of polymorphisms in alpha4 and alpha6 nicotinic receptor genes.

PubMed

Tritto, Theresa; Stitzel, Jerry A; Marks, Michael J; Romm, Elena; Collins, Allan C

2002-04-01

Several studies have shown that genetic factors influence the effects of nicotine on respiration, acoustic startle, Y-maze crosses and rears, heart rate and body temperature in the mouse. Recently, we identified restriction fragment length polymorphisms (RFLPs) associated with the alpha4 (Chrna4) and alpha6 (Chrna6) nicotinic cholinergic receptor genes in the recombinant inbred (RI) strains derived from the Long-Sleep (LS) and Short-Sleep (SS) mouse lines. The alpha4 polymorphism has been identified as a point-mutation at position 529 (threonine to alanine) and the alpha6 polymorphism has not yet been identified. The studies described here evaluated the potential role of these polymorphisms in regulating sensitivity to nicotine by constructing dose-response curves for the effects of nicotine on six responses in the LSxSS RI strains. The results obtained suggest that both of the polymorphisms may play a role in regulating variability in sensitivity to nicotine. Those RI strains carrying the LS-like alpha4 RFLP were significantly more sensitive to the effects of nicotine on Y-maze crosses and rears, temperature and respiration and were less sensitive to the effects of nicotine on acoustic startle than those strains carrying the SS-like alpha4 RFLP. Those RI strains carrying the LS-like alpha6 RFLP were more sensitive to the effects of nicotine on respiration and acoustic startle, and less sensitive to the effects of nicotine on Y-maze crosses than those strains carrying the SS-like alpha6 RFLP. These results suggest that genetically determined differences in sensitivity to nicotine may be explained, in part, by variability associated with at least two of the neuronal nicotinic receptor genes, alpha4 and alpha6.

Polymorphism and thermodynamic ground state of silver fulminate studied from van der Waals density functional calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yedukondalu, N.; Vaitheeswaran, G., E-mail: gvsp@uohyd.ernet.in

2014-06-14

Silver fulminate (AgCNO) is a primary explosive, which exists in two polymorphic phases, namely, orthorhombic (Cmcm) and trigonal (R3{sup ¯}) forms at ambient conditions. In the present study, we have investigated the effect of pressure and temperature on relative phase stability of the polymorphs using planewave pseudopotential approaches based on Density Functional Theory (DFT). van der Waals interactions play a significant role in predicting the phase stability and they can be effectively captured by semi-empirical dispersion correction methods in contrast to standard DFT functionals. Based on our total energy calculations using DFT-D2 method, the Cmcm structure is found to bemore » the preferred thermodynamic equilibrium phase under studied pressure and temperature range. Hitherto Cmcm and R3{sup ¯} phases denoted as α- and β-forms of AgCNO, respectively. Also a pressure induced polymorphic phase transition is seen using DFT functionals and the same was not observed with DFT-D2 method. The equation of state and compressibility of both polymorphic phases were investigated. Electronic structure and optical properties were calculated using full potential linearized augmented plane wave method within the Tran-Blaha modified Becke-Johnson potential. The calculated electronic structure shows that α, β phases are indirect bandgap insulators with a bandgap values of 3.51 and 4.43 eV, respectively. The nature of chemical bonding is analyzed through the charge density plots and partial density of states. Optical anisotropy, electric-dipole transitions, and photo sensitivity to light of the polymorphs are analyzed from the calculated optical spectra. Overall, the present study provides an early indication to experimentalists to avoid the formation of unstable β-form of AgCNO.« less

Polymorphic Transformation of Indomethacin during Hot Melt Extrusion Granulation: Process and Dissolution Control.

PubMed

Xu, Ting; Nahar, Kajalajit; Dave, Rutesh; Bates, Simon; Morris, Kenneth

2018-05-10

To study and elucidate the effect of the intensity and duration of processing stresses on the possible solid-state changes during a hot melt extrusion granulation process. Blends of α-indomethacin and PEG 3350 (w/w 4:1) were granulated using various screw sizes/designs on the melt extruder under different temperature regimes. Differential Scanning Calorimetry and X-ray Powder Diffraction were employed for characterization. The dissolution behavior of the pure polymorphs and the resulting granules was determined using in-situ fiber optic UV testing system. An XRPD quantitation method using Excel full pattern fitting was developed to determine the concentration of each constituent (amorphous, α and γ indomethacin and PEG) in samples collected from each functioning zone and in granules. Analysis of in-process samples and granules revealed that higher temperature (≥130°C) and shear stress accelerated the process induced phase transitions from amorphous and/or the α form to γ indomethacin during heating stage. However, rapid cooling resulted in an increased percentage of the α form allowing isolation of the meta-stable form. By determining the conditions that either prevent or facilitate process induced transformations of IMC polymorphs during melt granulation, a design space was developed to control the polymorph present in the resulting granules. This represents the conditions necessary to balance the thermodynamic relationships between the polymorphs of the IMC system and the kinetics of the possible transformations as a function of the processing stresses.

Using reweighting and free energy surface interpolation to predict solid-solid phase diagrams

NASA Astrophysics Data System (ADS)

Schieber, Natalie P.; Dybeck, Eric C.; Shirts, Michael R.

2018-04-01

Many physical properties of small organic molecules are dependent on the current crystal packing, or polymorph, of the material, including bioavailability of pharmaceuticals, optical properties of dyes, and charge transport properties of semiconductors. Predicting the most stable crystalline form at a given temperature and pressure requires determining the crystalline form with the lowest relative Gibbs free energy. Effective computational prediction of the most stable polymorph could save significant time and effort in the design of novel molecular crystalline solids or predict their behavior under new conditions. In this study, we introduce a new approach using multistate reweighting to address the problem of determining solid-solid phase diagrams and apply this approach to the phase diagram of solid benzene. For this approach, we perform sampling at a selection of temperature and pressure states in the region of interest. We use multistate reweighting methods to determine the reduced free energy differences between T and P states within a given polymorph and validate this phase diagram using several measures. The relative stability of the polymorphs at the sampled states can be successively interpolated from these points to create the phase diagram by combining these reduced free energy differences with a reference Gibbs free energy difference between polymorphs. The method also allows for straightforward estimation of uncertainties in the phase boundary. We also find that when properly implemented, multistate reweighting for phase diagram determination scales better with the size of the system than previously estimated.

Controlling the selective formation of calcium sulfate polymorphs at room temperature.

PubMed

Tritschler, Ulrich; Van Driessche, Alexander E S; Kempter, Andreas; Kellermeier, Matthias; Cölfen, Helmut

2015-03-23

Calcium sulfate is a naturally abundant and technologically important mineral with a broad scope of applications. However, controlling CaSO4 polymorphism and, with it, its final material properties still represents a major challenge, and to date there is no universal method for the selective production of the different hydrated and anhydrous forms under mild conditions. Herein we report the first successful synthesis of pure anhydrite from solution at room temperature. We precipitated calcium sulfate in alcoholic media at low water contents. Moreover, by adjusting the amount of water in the syntheses, we can switch between the distinct polymorphs and fine-tune the outcome of the reaction, yielding either any desired CaSO4 phase in pure state or binary mixtures with predefined compositions. This concept provides full control over phase selection in CaSO4 mineralization and may allow for the targeted fabrication of corresponding materials for use in various areas. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Donghui; Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi, Changning, Shanghai 200050; Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn

In this article, the polymorph selection of calcium carbonate has been successfully achieved in water-soluble carboxymethyl chitosan aqueous solution at different temperatures (25-95 {sup o}C). Vaterite is formed in carboxymethyl chitosan solution 25 {sup o}C accompanied with trace of calcite, whereas pure aragonite is obtained at 95 {sup o}C. Scanning electron microscopy and transmission electron microscopy analyses show that the products are formed from the recrystallization of nanometer crystallites. Thermodynamic and kinetic analyses reveal that the polymorph of calcium carbonate is controlled and selected by kinetics in various temperatures. As a heterogeneous nucleator and stabilizing agent, carboxymethyl chitosan changes themore » nucleation and growth of calcium carbonate from thermodynamic into kinetic control. Under kinetic limitation, the reaction rate of aragonite increases along with the elevating of temperature and surpasses the rate of vaterite above 327 K.« less

Ultrafast X-Ray Diffraction Studies of the Phase Transitions and Equation of State of Scandium Shock Compressed to 82 GPa

DOE PAGES

Briggs, R.; Gorman, M. G.; Coleman, A. L.; ...

2017-01-09

Using x-ray diffraction at the Linac Coherent Light Source x-ray free-electron laser, we have determined simultaneously and self-consistently the phase transitions and equation of state (EOS) of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Furthermore, shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearancemore » of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.« less

Zinc-blende to rocksalt transition in SiC in a laser-heated diamond-anvil cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daviau, Kierstin; Lee, Kanani K. M.

2017-04-18

We explore the stability of the ambient pressure zinc-blende polymorph (B3) structure of silicon carbide (SiC) at high pressures and temperatures where it transforms to the rocksalt (B1) structure. We find that the transition occurs ~40 GPa lower than previously measured when heated to moderately high temperatures. A lower transition pressure is consistent with the transition pressures predicted in numerous ab initio computations. We find a large volume decrease across the transition of ~17%, with the volume drop increasing at higher formation pressures, suggesting this transition is volume driven yielding a nearly pressure-independent Clapeyron slope. Such a dramatic density increasemore » occurring at pressure is important to consider in applications where SiC is exposed to extreme conditions, such as in industrial applications or planetary interiors.« less

Ultrafast X-Ray Diffraction Studies of the Phase Transitions and Equation of State of Scandium Shock Compressed to 82 GPa.

PubMed

Briggs, R; Gorman, M G; Coleman, A L; McWilliams, R S; McBride, E E; McGonegle, D; Wark, J S; Peacock, L; Rothman, S; Macleod, S G; Bolme, C A; Gleason, A E; Collins, G W; Eggert, J H; Fratanduono, D E; Smith, R F; Galtier, E; Granados, E; Lee, H J; Nagler, B; Nam, I; Xing, Z; McMahon, M I

2017-01-13

Using x-ray diffraction at the Linac Coherent Light Source x-ray free-electron laser, we have determined simultaneously and self-consistently the phase transitions and equation of state (EOS) of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearance of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.

Combined crystal structure prediction and high-pressure crystallization in rational pharmaceutical polymorph screening

PubMed Central

Neumann, M. A.; van de Streek, J.; Fabbiani, F. P. A.; Hidber, P.; Grassmann, O.

2015-01-01

Organic molecules, such as pharmaceuticals, agro-chemicals and pigments, frequently form several crystal polymorphs with different physicochemical properties. Finding polymorphs has long been a purely experimental game of trial-and-error. Here we utilize in silico polymorph screening in combination with rationally planned crystallization experiments to study the polymorphism of the pharmaceutical compound Dalcetrapib, with 10 torsional degrees of freedom one of the most flexible molecules ever studied computationally. The experimental crystal polymorphs are found at the bottom of the calculated lattice energy landscape, and two predicted structures are identified as candidates for a missing, thermodynamically more stable polymorph. Pressure-dependent stability calculations suggested high pressure as a means to bring these polymorphs into existence. Subsequently, one of them could indeed be crystallized in the 0.02 to 0.50 GPa pressure range and was found to be metastable at ambient pressure, effectively derisking the appearance of a more stable polymorph during late-stage development of Dalcetrapib. PMID:26198974

Single-crystal diffuse scattering studies on polymorphs of molecular crystals. I. The room-temperature polymorphs of the drug benzocaine.

PubMed

Chan, E J; Welberry, T R; Goossens, D J; Heerdegen, A P; Beasley, A G; Chupas, P J

2009-06-01

The drug benzocaine (ethyl 4-aminobenzoate), commonly used as a local anaesthetic, is a bimorphic solid at room temperature. Form (I) is monoclinic P2(1)/c, while the metastable form (II) is orthorhombic P2(1)2(1)2(1). Three-dimensional diffuse X-ray scattering data have been collected for the two forms on the 11-ID-B beamline at the Advanced Photon Source (APS). Both forms show strong and highly structured diffuse scattering. The data have been interpreted and analysed using Monte Carlo (MC) modelling on the basis that the scattering is purely thermal in origin and indicates the presence of highly correlated molecular motions. In both forms (I) and (II) broad diffuse streaks are observed in the 0kl section which indicate strong longitudinal displacement correlations between molecules in the 031 directions, extending over distances of up to 50 A. Streaks extending between Bragg peaks in the hk0 section normal to [100] correspond to correlated motions of chains of molecules extending along a that are linked by N-H...O=C hydrogen bonds and which occur together as coplanar ribbon pairs. The main difference between the two forms is in the dynamical behaviour of the ribbon pairs and in particular how they are able to slide relative to each other. While for form (I) a model involving harmonic springs is able to describe the motion satisfactorily, as simple excursions away from the average structure, there is evidence in form (II) of anharmonic effects that are precursors of a phase transition to a new low-temperature phase, form (III), that was subsequently found.

Genotype by temperature interactions in the metabolic rate of the Glanville fritillary butterfly.

PubMed

Niitepõld, Kristjan

2010-04-01

Metabolic rate is a highly plastic trait. Here I examine factors that influence the metabolic rate of the Glanville fritillary butterfly (Melitaea cinxia) in pupae and resting and flying adults. Body mass and temperature had consistent positive effects on metabolic rate in pupae and resting adults but not in flying adults. There was also a consistent nonlinear effect of the time of the day, which was strongest in pupae and weakest in flying adults. Flight metabolic rate was strongly affected by an interaction between the phosphoglucose isomerase (Pgi) genotype and temperature. Over a broad range of measurement temperatures, heterozygous individuals at a single nucleotide polymorphism (SNP) in Pgi had higher peak metabolic rate in flight, but at high temperatures homozygous individuals performed better. The two genotypes did not differ in resting metabolic rate, suggesting that the heterozygotes do not pay an additional energetic cost for their higher flight capacity. Mass-independent resting and flight metabolic rates were at best weakly correlated at the individual level, and therefore, unlike in many vertebrates, resting metabolic rate does not serve as a useful surrogate of the metabolic capacity of this butterfly.

Thermal evolution of the metastable r8 and bc8 polymorphs of silicon

DOE PAGES

Haberl, Bianca; Guthrie, Malcolm; Sinogeikin, Stanislav V.; ...

2015-01-28

The kinetics of two metastable polymorphs of silicon under thermal annealing was investigated. These phases with body-centered cubic bc8 and rhombohedral r8 structures can be formed upon pressure release from metallic silicon.We study these metastable polymorphs were formed by two different methods, via point loading and in a diamond anvil cell (DAC). Upon thermal annealing different transition pathways were detected. In the point loading case, the previously reported Si-XIII formed and was confirmed as a new phase with an as-yet-unidentified structure. In the DAC case, bc8-Si transformed to the hexagonal-diamond structure at elevated pressure, consistent with previous studies at ambientmore » pressure. In contrast, r8-Si transformed directly to diamond-cubic Si at a temperature of 255⁰C. In conclusion, these data were used to construct diagrams of the metastability regimes of the polymorphs formed in a DAC and may prove useful for potential technological applications of these metastable polymorphs.« less

Thermal evolution of the metastable r8 and bc8 polymorphs of silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haberl, Bianca; Guthrie, Malcolm; Sinogeikin, Stanislav V.

The kinetics of two metastable polymorphs of silicon under thermal annealing was investigated. These phases with body-centered cubic bc8 and rhombohedral r8 structures can be formed upon pressure release from metallic silicon.We study these metastable polymorphs were formed by two different methods, via point loading and in a diamond anvil cell (DAC). Upon thermal annealing different transition pathways were detected. In the point loading case, the previously reported Si-XIII formed and was confirmed as a new phase with an as-yet-unidentified structure. In the DAC case, bc8-Si transformed to the hexagonal-diamond structure at elevated pressure, consistent with previous studies at ambientmore » pressure. In contrast, r8-Si transformed directly to diamond-cubic Si at a temperature of 255⁰C. In conclusion, these data were used to construct diagrams of the metastability regimes of the polymorphs formed in a DAC and may prove useful for potential technological applications of these metastable polymorphs.« less

Non-linear thermal evolution of the crystal structure and phase transitions of LaFeO{sub 3} investigated by high temperature X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selbach, Sverre M.; Tolchard, Julian R.; Fossdal, Anita

2012-12-15

The crystal structure, anisotropic thermal expansion and structural phase transition of the perovskite LaFeO{sub 3} has been studied by high-temperature X-ray diffraction from room temperature to 1533 K. The structural evolution of the orthorhombic phase with space group Pbnm and the rhombohedral phase with R3{sup Macron }c structure of LaFeO{sub 3} is reported in terms of lattice parameters, thermal expansion coefficients, atomic positions, octahedral rotations and polyhedral volumes. Non-linear lattice expansion across the antiferromagnetic to paramagnetic transition of LaFeO{sub 3} at T{sub N}=735 K was compared to the corresponding behavior of the ferroelectric antiferromagnet BiFeO{sub 3} to gain insight tomore » the magnetoelectric coupling in BiFeO{sub 3}, which is also multiferroic. The first order phase transition of LaFeO{sub 3} from Pbnm to R3{sup Macron }c was observed at 1228{+-}9 K, and a subsequent transition to Pm3{sup Macron }m was extrapolated to occur at 2140{+-}30 K. The stability of the Pbnm and R3{sup Macron }c polymorphs of LaFeO{sub 3} is discussed in terms of the competing enthalpy and entropy of the two crystal polymorphs and the thermal evolution of the polyhedral volume ratio V{sub A}/V{sub B}. - Graphical abstract: Aniostropic thermal evolution of the lattice parameters and phase transition of LaFeO{sub 3}. Highlights: Black-Right-Pointing-Pointer The crystal structure of LaFeO{sub 3} is studied by HTXRD from RT to 1533 K. Black-Right-Pointing-Pointer A non-linear expansion across the Neel temperature is observed for LaFeO{sub 3}. Black-Right-Pointing-Pointer The ratio V{sub A}/V{sub B} is used to rationalize the thermal evolution of the structure.« less

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol.

PubMed

Barrio, Maria; Huguet, Judit; Rietveld, Ivo B; Robert, Benoît; Céolin, René; Tamarit, Josep-Lluis

2017-06-01

Understanding the polymorphic behavior of active pharmaceutical ingredients is important for formulation purposes and regulatory reasons. Metacetamol is an isomer of paracetamol and it similarly exhibits polymorphism. In the present article, it has been found that one of the polymorphs of metacetamol is only stable under increased pressure, which has led to the conclusion that metacetamol like paracetamol is a monotropic system under ordinary (= laboratory) conditions and that it becomes enantiotropic under pressure with the I-II-L triple point coordinates for metacetamol T I-II-L  = 535 ± 10 K and P I-II-L  = 692 ± 70 MPa. However, whereas for paracetamol the enantiotropy under pressure can be foreseen, because the metastable polymorph is denser, in the case of metacetamol this is not possible, as the metastable polymorph is less dense than the stable one. The existence of the stability domain for the less dense polymorph of metacetamol can only be demonstrated by the construction of the topological phase diagram as presented in this article. It is a delicate interplay between the specific volume differences and the enthalpy differences causing the stability domain of the less dense polymorph to be sandwiched between the denser polymorph and the liquid. Metacetamol shares this behavior with bicalutamide and fluoxetine nitrate. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Lead(ii) soaps: crystal structures, polymorphism, and solid and liquid mesophases.

PubMed

Martínez-Casado, F J; Ramos-Riesco, M; Rodríguez-Cheda, J A; Redondo-Yélamos, M I; Garrido, L; Fernández-Martínez, A; García-Barriocanal, J; da Silva, I; Durán-Olivencia, M; Poulain, A

2017-07-05

The long-chain members of the lead(ii) alkanoate series or soaps, from octanoate to octadecanoate, have been thoroughly characterized by means of XRD, PDF analysis, DSC, FTIR, ssNMR and other techniques, in all their phases and mesophases. The crystal structures at room temperature of all of the members of the series are now solved, showing the existence of two polymorphic forms in the room temperature crystal phase, different to short and long-chain members. Only nonanoate and decanoate present both forms, and this polymorphism is proven to be monotropic. At higher temperature, these compounds present a solid mesophase, defined as rotator, a liquid crystal phase and a liquid phase, all of which have a similar local arrangement. Since some lead(ii) soaps appear as degradation compounds in oil paintings, the solved crystal structures of lead(ii) soaps can now be used as fingerprints for their detection using X-ray diffraction. Pair distribution function analysis on these compounds is very similar in the same phases and mesophases for the different members, showing the same short range order. This observation suggests that this technique could also be used in the detection of these compounds in disordered phases or in the initial stages of formation in paintings.

Thermal vibrations and polymorphic β → γ transition in cerium

NASA Astrophysics Data System (ADS)

Agafonov, S. S.; Blanter, M. S.; Glazkov, V. P.; Somenkov, V. A.; Shushunov, M. N.

2010-10-01

Method of neutron diffraction was used to determine the temperature dependence of the Debye-Waller factor and the related thermal atomic displacements for two polymorphic modifications of cerium, namely, for β-Ce with a double hexagonal closed-packed (dhcp) structure and for γ-Ce with a face-centered cubic (fcc) structure. It has been shown that the phase transition does not lead to substantial changes in the root-mean-square thermal atomic displacements and that the Debye temperatures of the two modifications are close: 131 K for β-Ce and 127 K for γ-Ce. However, the relative (with respect to the lattice parameters) displacements along the axes change considerably. The transition from the anisotropic hexagonal to the isotropic cubic modification leads, because of a redistribution of thermal atomic displacements along the crystallographic axes, to a decrease in the maximum values of these quantities and to a weakening of their temperature dependence. It has also been shown that a change in the thermal atomic vibrations and in the vibrational contribution to the entropy of the polymorphic transformations is connected with the sign of the volume effect of the transformation (stronger upon a positive effect and weaker, upon a negative one). The reasons for this behavior are discussed.

Non-hydrolytic Sol-gel Synthesis of Tin Sulfides

NASA Astrophysics Data System (ADS)

Kaur, Rajvinder

The non-hydrolytic sol-gel (NHSG) process is an effective low temperature route well known for preparing homogeneous metal oxides. Thermodynamically as well as kinetically favored products, which cannot be prepared with the traditional solid-state routes, can be produced using NHSG. This project is focused on the exploration of NHSG synthesis of binary tin sulfides. In the past few years, metal sulfides have been the subject of significant interest. Much effort has been devoted to understand these materials because of their potential applications in electronic, optical, and superconductor devices.4 Among these materials, tin sulfides are materials of technological importance, which are being explored as semiconductors, anode materials for Li ion batteries, photoconductors, photocatalysts and absorber layer materials in photovoltaic solar cell devices. All of these applications depend upon features like homogeneity, oxidation state, high surface area and purity of the materials. These properties can be difficult to achieve by employing traditional synthetic routes, which require high temperatures due to slow diffusion, limiting the products to thermodynamically stable phases and prohibiting control over properties like particle size and surface area. A variety of low temperature methods are being explored due to the increased demand for such advanced materials. This project is focused on exploring the NHSG approach to synthesize binary tin sulfides, with the main goal of establishing conditions for the targeted synthesis of different tin sulfide polymorphs with controlled particle size. Being non-oxide materials, tin sulfides can be air sensitive, which requires special attention in handling. All reactions were carried out in absence of oxygen. This project explores the reaction of tin halides with thioethers in a dry solvent medium, leading to the formation of tin sulfides. There are a number of synthetic parameters that can be varied for the NHSG approach. A systematic study was carried out to understand the influence of all reaction variables, which include tin halides, thioethers, solvents, time, temperature, stoichiometry and concentration. Fine tuning of all reaction variables was carried out. The crystallization and phase stability of the as-recovered products was further studied by heat treatments of the samples. A detailed investigation of synthetic variables during NHSG reactions resulted in controlled synthesis of two crystalline tin sulfide polymorphs, SnS and SnS2. A third polymorph, Sn2S3, could be obtained after heat treatments in the temperature range of 400 to 500 °C. Conditions for the targeted synthesis of particles with various sizes and morphologies were established. Samples were characterized by powder X-ray diffraction, electron microscopy in combination with EDS, CHNS analysis and thermo gravimetric/differential thermal analysis.

Are "functionally related polymorphisms" of renin-angiotensin-aldosterone system gene polymorphisms associated with hypertension?

PubMed

Hahntow, Ines N; Mairuhu, Gideon; van Valkengoed, Irene Gm; Koopmans, Richard P; Michel, Martin C

2010-06-02

Genotype-phenotype association studies are typically based upon polymorphisms or haplotypes comprised of multiple polymorphisms within a single gene. It has been proposed that combinations of polymorphisms in distinct genes, which functionally impact the same phenotype, may have stronger phenotype associations than those within a single gene. We have tested this hypothesis using genes encoding components of the renin-angiotensin-aldosterone system and the high blood pressure phenotype. Our analysis is based on 1379 participants of the cross-sectional SUNSET study randomly selected from the population register of Amsterdam. Each subject was genotyped for the angiotensinogen M235T, the angiotensin-converting enzyme insertion/deletion and the angiotensin II type 1 receptor A1166C polymorphism. The phenotype high blood pressure was defined either as a categorical variable comparing hypertension versus normotension as in most previous studies or as a continuous variable using systolic, diastolic and mean blood pressure in a multiple regression analysis with gender, ethnicity, age, body-mass-index and antihypertensive medication as covariates. Genotype-phenotype relationships were explored for each polymorphism in isolation and for double and triple polymorphism combinations. At the single polymorphism level, only the A allele of the angiotensin II type 1 receptor was associated with a high blood pressure phenotype. Using combinations of polymorphisms of two or all three genes did not yield stronger/more consistent associations. We conclude that combinations of physiologically related polymorphisms of multiple genes, at least with regard to the renin-angiotensin-aldosterone system and the hypertensive phenotype, do not necessarily offer additional benefit in analyzing genotype/phenotype associations.

Modeling dynamic beta-gamma polymorphic transition in Tin

NASA Astrophysics Data System (ADS)

Chauvin, Camille; Montheillet, Frank; Petit, Jacques; CEA Gramat Collaboration; EMSE Collaboration

2015-06-01

Solid-solid phase transitions in metals have been studied by shock waves techniques for many decades. Recent experiments have investigated the transition during isentropic compression experiments and shock-wave compression and have highlighted the strong influence of the loading rate on the transition. Complementary data obtained with velocity and temperature measurements around the polymorphic transition beta-gamma of Tin on gas gun experiments have displayed the importance of the kinetics of the transition. But, even though this phenomenon is known, modeling the kinetic remains complex and based on empirical formulations. A multiphase EOS is available in our 1D Lagrangian code Unidim. We propose to present the influence of various kinetic laws (either empirical or involving nucleation and growth mechanisms) and their parameters (Gibbs free energy, temperature, pressure) on the transformation rate. We compare experimental and calculated velocities and temperature profiles and we underline the effects of the empirical parameters of these models.

The ammonia-water system and the chemical differentiation of icy satellites

USGS Publications Warehouse

Hogenboom, D.L.; Kargel, J.S.; Consolmagno, G.J.; Holden, T.C.; Lee, L.; Buyyounouski, M.

1997-01-01

We report the discovery of the first high-pressure polymorphs of ammonia hydrates: ammonia monohydrate II and ammonia dihydrate II. The subsolidus transitions and melting curves of these substances are shown by their volume-temperature functions; uncalibrated calorimetry corroborates these phase changes. From 20 to 300 MPa ammonia dihydrate and ice melt at a eutectic to form water-rich liquids; at lower and higher pressures, ammonia dihydrate melts incongruently to ammonia-rich liquids. The new data are consistent with independently known thermodynamic parameters of the ammonia-water system. These results fill in an important region of pressure-temperature space not previously studied; a body of previous data reported by other investigators covers a complementary region (higher pressures), but in the light of the new data those earlier results now appear to have been misinterpreted. We show that a suitable reinterpretation of the previous data supports the identification of at least one high-pressure polymorph of each compound. The behavior of the system H2O-NH3in many ways follows that of MgO-SiO2, and the roles of ammonia-water in icy satellite evolution may parallel those of magnesium silicates in Earth's structure, volcanism, and deep mantle tectonism. Pressure-related effects, including a pressure influence on the ammonia content of cryomagmas, might be significant in determining some potentially observable aspects of cryovolcanic morphologies, surface compositions, and interior structures of icy satellites. ?? 1997 Academic Press.

Vitamin K 3 family members - Part II: Single crystal X-ray structures, temperature-induced packing polymorphism, magneto-structural correlations and probable anti-oncogenic candidature

NASA Astrophysics Data System (ADS)

Rane, Sandhya; Ahmed, Khursheed; Salunke-Gawali, Sunita; Zaware, Santosh B.; Srinivas, D.; Gonnade, Rajesh; Bhadbhade, Mohan

2008-12-01

Temperature-induced packing polymorphism is observed for vitamin K 3 (menadione, 3-methyl-1,4-naphthoquinone, 1). Form 1a crystallizes at 300 K and 1b at 277 K both in the same space group P2 1/ c. Form 1b contains one molecule per asymmetric unit, performing anisotropy in g-factor viz. g z = 2.0082, g y = 2.0055 and g x = 2.0025, whereas form 1a contains two molecules in its asymmetric unit. Vitamin K 3 family members 2, [2-hydroxy vitamin K 3] and 3, [2-hydroxy-1-oximino vitamin K 3] also perform intrinsic neutral active naphthosemiquinone valence tautomers even in dark having spin concentrations due to hydrogen bonding and aromatic stacking interactions which are compared to vitamin K 3. The significant lateral C-H⋯O and O-H⋯π bifurcated or π-π ∗ interactions are discussed for molecular associations and radical formations. X-ray structure of 3 revealed π-π ∗ stack dimers as radicals signatured in EPR as triplet with five hyperfine splits [ Ā( 14N) = 11.9 G]. The centrosymmetric biradicals in 3 show diamagnetism at high temperature but below 10 K it shows paramagnetism with μeff as 0.19 B.M. Vitamin K 3 and its family members inhibit biological activities of acid phosphatase ( APase), which are proportional to their spin concentrations. This may relate to their probable anti-oncogenic candidature in future.

A polymorph of terephthalaldehyde.

PubMed

Teng, Lei; Wang, Zhiguo

2008-07-23

A new ortho-rhom-bic polymorph of terephthalaldehyde, C(8)H(6)O(2), with a melting point of 372 K, has been obtained by recrystallization from ethanol. At room temperature, the crystals transform into the well known monoclinic form, with a melting point of 389 K. The crystal structure of the monoclinic form involves C-H⋯O hydrogen bonds, but no such bonds are observed in the orthorhombic form. The molecule is planar.

Quantification Of 4H- To 3C-Polymorphism In Silicon Carbide (SiC) Epilayers And An Investigation Of Recombination-Enhanced Dislocation Motion In SiC By Optical Emission Microscopy (Oem) Techniques

NASA Technical Reports Server (NTRS)

Speer, Kevin M.

2004-01-01

Environments that impose operational constraints on conventional silicon-(Si) based semiconductor devices frequently appear in military- and space-grade applications. These constraints include high temperature, high power, and high radiation environments. Silicon carbide (SiC), an alternative type of semiconductor material, has received abundant research attention in the past few years, owing to its radiation-hardened properties as well as its capability to withstand high temperatures and power levels. However, the growth and manufacture of SiC devices is still comparatively immature, and there are severe limitations in present crystal growth and device fabrication processes. Among these limitations is a variety of crystal imperfections known as defects. These imperfections can be point defects (e.g., vacancies and interstitials), line defects (e.g., edge and screw dislocations), or planar defects (e.g., stacking faults and double-positioning boundaries). All of these defects have been experimentally shown to be detrimental to the performance of electron devices made from SiC. As such, it is imperative that these defects are significantly reduced in order for SiC devices to become a viable entity in the electronics world. The NASA Glenn High Temperature Integrated Electronics & Sensors Team (HTIES) is working to identify and eliminate these defects in SiC by implementing improved epitaxial crystal growth procedures. HTIES takes two-inch SiC wafers and etches patterns, producing thousands of mesas into each wafer. Crystal growth is then carried out on top of these mesas in an effort to produce films of improved quality-resulting in electron devices that demonstrate superior performance-as well as fabrication processes that are cost-effective, reliable, and reproducible. In this work, further steps are taken to automate HTIES' SiC wafer inspection system. National Instruments LabVIEW image processing and pattern recognition routines are developed that are capable of quantifying and mapping defects on both the substrate and mesa surfaces, and of quantifying polymorphic changes in the grown materials. In addition, an optical emission microscopy (OEM) system is developed that will facilitate comprehensive study of recombination-enhanced dislocation motion (REDM).

Drug recrystallization using supercritical anti-solvent (SAS) process with impinging jets: Effect of process parameters

NASA Astrophysics Data System (ADS)

Careno, Stéphanie; Boutin, Olivier; Badens, Elisabeth

2012-03-01

The aim of this study is to improve mixing in supercritical anti-solvent process (SAS) with impinging jets in order to form finer particles of sulfathiazole, a poorly water-soluble drug. The influence of several process parameters upon the powder characteristics is studied. Parameters are jets' velocity (0.25 m s-1 to 25.92 m s-1), molar ratio solvent/CO2 (2.5% to 20%), temperature (313 K to 343 K), pressure (10 MPa to 20 MPa) and sulfathiazole concentration in the organic solution (0.5% to 1.8%). Two solvents are used: acetone and methanol. Smaller particles with a more homogeneous morphology are obtained from acetone solutions. For the smallest jets' velocity, corresponding to a non-atomized jet, the stable polymorphic form is obtained, pure or in mixture. At this velocity, pressure is the most influential parameter controlling the polymorphic nature of the powder formed. The pure stable polymorph is formed at 20 MPa. Concerning the particle size, the most influential parameters are temperature and sulfathiazole concentration. The use of impinging jets with different process parameters allows the crystallization of four polymorphs among the five known, and particle sizes are varied. This work demonstrates the studied device ability of the polymorph and the size control. A comparison with the classical SAS process shows that particle size, size distribution and morphology of particles crystallized with impinging jets are different from the ones obtained with classical SAS introduction device in similar operating conditions. Mean particle sizes are significantly smaller and size distributions are narrower with impinging jets device.

Amorphization of nanocrystalline monoclinic ZrO2 by swift heavy ion irradiation.

PubMed

Lu, Fengyuan; Wang, Jianwei; Lang, Maik; Toulemonde, Marcel; Namavar, Fereydoon; Trautmann, Christina; Zhang, Jiaming; Ewing, Rodney C; Lian, Jie

2012-09-21

Bulk ZrO(2) polymorphs generally have an extremely high amorphization tolerance upon low energy ion and swift heavy ion irradiation in which ballistic interaction and ionization radiation dominate the ion-solid interaction, respectively. However, under very high-energy irradiation by 1.33 GeV U-238, nanocrystalline (40-50 nm) monoclinic ZrO(2) can be amorphized. A computational simulation based on a thermal spike model reveals that the strong ionizing radiation from swift heavy ions with a very high electronic energy loss of 52.2 keV nm(-1) can induce transient zones with temperatures well above the ZrO(2) melting point. The extreme electronic energy loss, coupled with the high energy state of the nanostructured materials and a high thermal confinement due to the less effective heat transport within the transient hot zone, may eventually be responsible for the ionizing radiation-induced amorphization without transforming to the tetragonal polymorph. The amorphization of nanocrystalline zirconia was also confirmed by 1.69 GeV Au ion irradiation with the electronic energy loss of 40 keV nm(-1). These results suggest that highly radiation tolerant materials in bulk forms, such as ZrO(2), may be radiation sensitive with the reduced length scale down to the nano-metered regime upon irradiation above a threshold value of electronic energy loss.

Kinetic control in the synthesis of metastable polymorphs: Bixbyite-to-Rh{sub 2}O{sub 3}(II)-to-corundum transition in In{sub 2}O{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bekheet, Maged F., E-mail: maged.bekheet@ceramics.tu-berlin.de; Fachgebiet Keramische Werkstoffe, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin; Schwarz, Marcus R.

2015-09-15

An example for kinetic control of a solid-state phase transformation, in which the system evolves via the path with the lowest activation barrier rather than ending in the thermodynamically most favorable state, has been demonstrated. As a case study, the phase transitions of indium sesquioxide (In{sub 2}O{sub 3}) have been guided by theoretical calculations and followed in situ under high-pressure high-temperature conditions in multi-anvil assemblies. The corundum-type rh-In{sub 2}O{sub 3} has been synthesized from stable bixbyite-type c-In{sub 2}O{sub 3} in two steps: first generating orthorhombic Rh{sub 2}O{sub 3}-II-type o′-In{sub 2}O{sub 3} which is thermodynamically stable at 8.5 GPa/850 °C and,more » thereafter, exploiting the preferred kinetics in the subsequent transformation to the rh-In{sub 2}O{sub 3} during decompression. This synthesis strategy of rh-In{sub 2}O{sub 3} was confirmed ex situ in a toroid-type high-pressure apparatus at 8 GPa and 1100 °C. The pressure–temperature phase diagrams have been constructed and the stability fields of In{sub 2}O{sub 3} polymorphs and the crystallographic relationship between them have been discussed. - Graphical abstract: In situ energy-dispersive XRD patterns in multi-anvil assemblies show the sequence of phase transition c-In{sub 2}O{sub 3}→o′-In{sub 2}O{sub 3}→rh-In{sub 2}O{sub 3} under particular pressure and temperature conditions. The tick marks refer to the calculated Bragg positions of bixbyite-type (c-In{sub 2}O{sub 3}), Rh{sub 2}O{sub 3}-II-type (o–-In2O{sub 3}) and corundum-type (rh-In{sub 2}O{sub 3}). - Highlights: • The solid-state synthesis methods can be employed for obtaining metastable phases. • The phase transition of In{sub 2}O{sub 3} was guided by DFT calculations. • The phase transition of In{sub 2}O{sub 3} was followed in situ under HP–HT conditions. • Orthorhombic o′-In{sub 2}O{sub 3} polymorph was synthesized from c-In{sub 2}O{sub 3} at 8.5 GPa/850 °C. • Metastable rh-In{sub 2}O{sub 3} was obtained from o′-In{sub 2}O{sub 3} at 5.5 GPa during decompression.« less

Formation of ferromagnetic molecular thin films from blends by annealing

PubMed Central

Robaschik, Peter; Ma, Ye; Din, Salahud

2017-01-01

We report on a new approach for the fabrication of ferromagnetic molecular thin films. Co-evaporated films of manganese phthalocyanine (MnPc) and tetracyanoquinodimethane (TCNQ) have been produced by organic molecular beam deposition (OMBD) on rigid (glass, silicon) and flexible (Kapton) substrates kept at room temperature. The MnPc:TCNQ films are found to be entirely amorphous due to the size mismatch of the molecules. However, by annealing while covering the samples highly crystalline MnPc films in the β-polymorph can be obtained at 60 °C lower than when starting with pure MnPc films. The resulting films exhibit substantial coercivity (13 mT) at 2 K and a Curie temperature of 11.5 K. PMID:28900600

Selective nucleation of iron phthalocyanine crystals on micro-structured copper iodide.

PubMed

Rochford, Luke A; Ramadan, Alexandra J; Heutz, Sandrine; Jones, Tim S

2014-12-14

Morphological and structural control of organic semiconductors through structural templating is an efficient route by which to tune their physical properties. The preparation and characterisation of iron phthalocyanine (FePc)-copper iodide (CuI) bilayers at elevated substrate temperatures is presented. Thin CuI(111) layers are prepared which are composed of isolated islands rather than continuous films previously employed in device structures. Nucleation in the early stages of FePc growth is observed at the edges of islands rather than on the top (111) faces with the use of field emission scanning electron microscopy (FE-SEM). Structural measurements show two distinct polymorphs of FePc, with CuI islands edges nucleating high aspect ratio FePc crystallites with modified intermolecular spacing. By combining high substrate temperature growth and micro-structuring of the templating CuI(111) layer structural and morphological control of the organic film is demonstrated.

Effects of allelic variations in starch synthesis-related genes on grain quality traits of Korean nonglutinous rice varieties under different temperature conditions

PubMed Central

Mo, Young-Jun; Jeung, Ji-Ung; Shin, Woon-Chul; Kim, Ki-Young; Ye, Changrong; Redoña, Edilberto D.; Kim, Bo-Kyeong

2014-01-01

Influences of allelic variations in starch synthesis-related genes (SSRGs) on rice grain quality were examined. A total of 187 nonglutinous Korean rice varieties, consisting of 170 Japonica and 17 Tongil-type varieties, were grown in the field and in two greenhouse conditions. The percentages of head rice and chalky grains, amylose content, alkali digestion value, and rapid visco-analysis characteristics were evaluated in the three different environments. Among the 10 previously reported SSRG markers used in this study, seven were polymorphic, and four of those showed subspecies-specific allele distributions. Six out of the seven polymorphic SSRG markers were significantly associated with at least one grain quality trait (R2 > 0.1) across the three different environments. However, the association level and significance were markedly lower when the analysis was repeated using only the 170 Japonica varieties. Similarly, the significant associations between SSRG allelic variations and changes in grain quality traits under increased temperature were largely attributable to the biased allele frequency between the two subpopulations. Our results suggest that within Korean Japonica varieties, these 10 major SSRG loci have been highly fixed during breeding history and variations in grain quality traits might be influenced by other genetic factors. PMID:24987303

Genetic polymorphisms in lung disease: bandwagon or breakthrough?

PubMed Central

Iannuzzi, Michael C; Maliarik, Mary; Rybicki, Benjamin

2002-01-01

The study of genetic polymorphisms has touched every aspect of pulmonary and critical care medicine. We review recent progress made using genetic polymorphisms to define pathophysiology, to identify persons at risk for pulmonary disease and to predict treatment response. Several pitfalls are commonly encountered in studying genetic polymorphisms, and this article points out criteria that should be applied to design high-quality genetic polymorphism studies. PMID:11980584

The New Superconductor tP-SrPd2Bi2: Structural Polymorphism and Superconductivity in Intermetallics.

PubMed

Xie, Weiwei; Seibel, Elizabeth M; Cava, Robert J

2016-04-04

We consider a system where structural polymorphism suggests the possible existence of superconductivity through the implied structural instability. SrPd2Bi2 has two polymorphs, which can be controlled by the synthesis temperature: a tetragonal form (CaBe2Ge2-type) and a monoclinic form (BaAu2Sb2-type). Although the crystallographic difference between the two forms may, at first, seem trivial, we show that tetragonal SrPd2Bi2 is superconducting at 2.0 K, whereas monoclinic SrPd2Bi2 is not. We rationalize this finding and place it in context with other 1-2-2 phases.

The nature, distribution and genesis of the coesite and stishovite associated with the pseudotachylite of the Vredefort Dome, South Africa

NASA Astrophysics Data System (ADS)

Martini, J. E. J.

1991-04-01

The Vredefort Dome represents the uplift centre of a well known 2.00 Ga old impact structure of unusually large magnitude. Shock features like shatter cones, planar features and high-pressure silica polymorphs are common. The present study deals with the description, mode of occurrence, field distribution and post-shock metamorphic alteration of coesite and stishovite which were poorly documented up to now. These minerals occur as unusually large crystals in the quartzite of the wall rock in contact with very thin pseudotachylite veins. In the pseudotachylite itself, which can be interpreted as a friction and/or a shock recovery melt, fine needles of kyanite are ubiquitous. It is proposed that these thin pseudotachylites (A-type) formed during the transit of the shock wave. They preceded the development of thick pseudotachylite and microbreccia veins (B-type) which formed during the tensional period which immediately followed. From comparison with the model of formation of high-pressure polymorphs in porous sandstone, it is suggested that higher pressure and stress was concentrated along the A-type veins at the arrival of the shock front. At this time the quartz was transformed into a "high-pressure phase" which was probably poorly crystalline. Behind the shock front, that is during the rarefaction, the pressure was progressively released and the polymorphs crystallized from this initial "high-pressure phase". Stishovite crystallized first, followed by coesite. The high-pressure conditions may have lasted an unusually long time due to the magnitude of the Vredefort impact. This long time, probably about one second, may account for the large size of the coesite and stishovite crystals. Most of the high-pressure silica polymorphs are corroded to a variable degree by secondary quartz and preserved only in a restricted area of the impact structure. This alteration is attributed to post-shock metamorphism due to the temperature of the rock before impact plus the heat left after shock recovery. Some of the evidence put forward by authors against the impact model is discussed according to the facts arising from this investigation. It is concluded that an origin by impact remains the simplest and most realistic model to explain the origin of the Vredefort Dome.

Polymorphic transition of tin under shock wave compression: Experimental results

NASA Astrophysics Data System (ADS)

Chauvin, C.; Petit, J.; Sinatti, F.

2012-08-01

In this work, the β-bct polymorphic transition in tin is investigated by means of plate impact experiments. The Sn target surface is observed in a partially released state obtained thanks to a transparent lithium fluoride (LiF) anvil. We report both measurements of interface velocity and temperature obtained using Photon Doppler Velocimetry and IR optical pyrometer on shock-loaded tin from 8 to 16 GPa. We show that the Mabire Model EOS associated to the SCG plasticity model provides an overall good estimate of the velocity profiles. However, depnding on the shock amplitude, its prediction of the temperature profile may be less satisfactory, hence underlining the need for future improvements in terms of phase transition kinetics description.

CsSnI[subscript 3]: Semiconductor or Metal? High Electrical Conductivity and Strong Near-Infrared Photoluminescence from a Single Material. High Hole Mobility and Phase-Transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, In; Song, Jung-Hwan; Im, Jino

CsSnI{sub 3} is an unusual perovskite that undergoes complex displacive and reconstructive phase transitions and exhibits near-infrared emission at room temperature. Experimental and theoretical studies of CsSnI{sub 3} have been limited by the lack of detailed crystal structure characterization and chemical instability. Here we describe the synthesis of pure polymorphic crystals, the preparation of large crack-/bubble-free ingots, the refined single-crystal structures, and temperature-dependent charge transport and optical properties of CsSnI{sub 3}, coupled with ab initio first-principles density functional theory (DFT) calculations. In situ temperature-dependent single-crystal and synchrotron powder X-ray diffraction studies reveal the origin of polymorphous phase transitions of CsSnI{submore » 3}. The black orthorhombic form of CsSnI{sub 3} demonstrates one of the largest volumetric thermal expansion coefficients for inorganic solids. Electrical conductivity, Hall effect, and thermopower measurements on it show p-type metallic behavior with low carrier density, despite the optical band gap of 1.3 eV. Hall effect measurements of the black orthorhombic perovskite phase of CsSnI{sub 3} indicate that it is a p-type direct band gap semiconductor with carrier concentration at room temperature of {approx} 10{sup 17} cm{sup -3} and a hole mobility of {approx} 585 cm{sup 2} V{sup -1} s{sup -1}. The hole mobility is one of the highest observed among p-type semiconductors with comparable band gaps. Its powders exhibit a strong room-temperature near-IR emission spectrum at 950 nm. Remarkably, the values of the electrical conductivity and photoluminescence intensity increase with heat treatment. The DFT calculations show that the screened-exchange local density approximation-derived band gap agrees well with the experimentally measured band gap. Calculations of the formation energy of defects strongly suggest that the electrical and light emission properties possibly result from Sn defects in the crystal structure, which arise intrinsically. Thus, although stoichiometric CsSnI{sub 3} is a semiconductor, the material is prone to intrinsic defects associated with Sn vacancies. This creates highly mobile holes which cause the materials to appear metallic.« less

Effect of supersaturation on L-glutamic acid polymorphs under droplet-based microchannels

NASA Astrophysics Data System (ADS)

Jiang, Nan; Wang, Zhanzhong; Dang, Leping; Wei, Hongyuan

2016-07-01

Supersaturation is an important controlling factor for crystallization process and polymorphism. Droplet-based microchannels and conventional crystallization were used to investigate polymorphs of L-gluatamic acid in this work. The results illustrate that it is easy to realize the accurate and rapid control of the crystallization temperature in the droplets, which is especially beneficial to heat and mass transfer during crystallization. It is also noted that higher degree of supersaturation favors the nucleation of α crystal form, while lower degree of supersaturation favors the nucleation of β crystal form under droplet-based microchannels for L-gluatamic acid. In addition, there is a different nucleation behavior to be found under droplet-based microchannels both for the β form and α form of L-glutamic acid. This new finding can provide important insight into the development and design of investigation meanings for drug polymorph.

A Two-Dimensional 'Zigzag' Silica Polymorph on a Metal Support.

PubMed

Kuhness, David; Yang, Hyun Jin; Klemm, Hagen W; Prieto, Mauricio; Peschel, Gina; Fuhrich, Alexander; Menzel, Dietrich; Schmidt, Thomas; Yu, Xin; Shaikhutdinov, Shamil; Lewandowski, Adrian; Heyde, Markus; Kelemen, Anna; Włodarczyk, Radosław; Usvyat, Denis; Schütz, Martin; Sauer, Joachim; Freund, Hans-Joachim

2018-05-16

We present a new polymorph of the two-dimensional (2D) silica film with a characteristic 'zigzag' line structure and a rectangular unit cell which forms on a Ru(0001) metal substrate. This new silica polymorph may allow for important insights into growth modes and transformations of 2D silica films as a model system for the study of glass transitions. Based on scanning tunneling microscopy, low energy electron diffraction, infrared reflection absorption spectroscopy, and X-ray photoelectron spectroscopy measurements on the one hand, and density functional theory calculations on the other, a structural model for the 'zigzag' polymorph is proposed. In comparison to established monolayer and bilayer silica, this 'zigzag' structure system has intermediate characteristics in terms of coupling to the substrate and stoichiometry. The silica 'zigzag' phase is transformed upon reoxidation at higher annealing temperature into a SiO 2 silica bilayer film which is chemically decoupled from the substrate.

1-Nitro-4-(4-nitro-phen-oxy)benzene: a second monoclinic polymorph.

PubMed

Naz, Mehwish; Akhter, Zareen; McKee, Vickie; Nadeem, Arif

2013-11-06

In the title compound, C12H8N2O5, the aromatic rings are inclined to one another by 56.14 (7)°. The nitro groups are inclined by to the benzene rings to which they are attached by 3.86 (17) and 9.65 (15)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming a three-dimensional structure. The title compound is a new monoclinic polymorph, crystallizing in space group P21/c. The first polymorph crystallized in space group C2/c and the mol-ecule possesses twofold rotation symmetry. Two low-temperature structures of this polymorph (150 K and 100 K, respectively) have been reported [Meciarova et al. (2004). Private Communication (refcode IXOGAD). CCDC, Cambridge, England, and Dey & Desiraju (2005). Chem. Commun. pp. 2486-2488].

Two Polymorphs of an Organic-Zincophosphate Incorporating a Terephthalate Bridging Ligand in an Unusual Bonding Mode.

PubMed

Wang, Chih-Min; Pan, Ming-Feng; Chen, Yen-Chieh; Lin, Hsiu-Mei; Chung, Mei-Ying; Wen, Yuh-Sheng; Lii, Kwang-Hwa

2017-07-17

Two new polymorphs of a zinc phosphate incorporating the terephthalate organic ligand 1,4-benzenedicarboxylate (BDC), (H 2 DA)Zn 2 (cis-BDC)(HPO 4 ) 2 (1) and (H 2 DA)Zn 2 (trans-BDC)(HPO 4 ) 2 (2), where DA = 1,7-diaminoheptane, were synthesized via a hydro(solvo)thermal method at different reaction temperatures and structurally characterized by single-crystal X-ray diffraction. Interestingly, the BDC ligands, which adopt the bis-monodentate coordination model with a unusual cis type for compound 1 and with a trans linkage for compound 2, bridge the Zn atoms of the inorganic layers in the generation of two polymorphs with structural diversities (one kind of arrangement of the layered zincophosphate layer in 1; the flat and zigzag sheets of inorganic networks in 2). A simple method for tuning the optical luminescence of the title compound from blue, red, green, yellow, and pink to white emission by stirring powdered samples in lanthanide-cation-containing aqueous ethanol solutions at room temperature for 1-2 h is also presented.

Phase stability of iron germanate, FeGeO3, to 127 GPa

NASA Astrophysics Data System (ADS)

Dutta, R.; Tracy, S. J.; Stan, C. V.; Prakapenka, V. B.; Cava, R. J.; Duffy, T. S.

2018-04-01

The high-pressure behavior of germanates is of interest as these compounds serve as analogs for silicates of the deep Earth. Current theoretical and experimental studies of iron germanate, FeGeO3, are limited. Here, we have examined the behavior of FeGeO3 to 127 GPa using the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. Upon compression at room temperature, the ambient-pressure clinopyroxene phase transforms to a disordered triclinic phase [FeGeO3 (II)] at 18 GPa in agreement with earlier studies. An additional phase transition to FeGeO3 (III) occurs above 54 GPa at room temperature. Laser-heating experiments ( 1200-2200 K) were conducted at three pressures (33, 54, and 123 GPa) chosen to cover the stability regions of different GeO2 polymorphs. In all cases, we observe that FeGeO3 dissociates into GeO2 + FeO at high pressure and temperature conditions. Neither the perovskite nor the post-perovskite phase was observed up to 127 GPa at ambient or high temperatures. The results are consistent with the behavior of FeSiO3, which also dissociates into a mixture of the oxides (FeO + SiO2) at least up to 149 GPa.

Strain-Induced Extrinsic High-Temperature Ferromagnetism in the Fe-Doped Hexagonal Barium Titanate

PubMed Central

Zorko, A.; Pregelj, M.; Gomilšek, M.; Jagličić, Z.; Pajić, D.; Telling, M.; Arčon, I.; Mikulska, I.; Valant, M.

2015-01-01

Diluted magnetic semiconductors possessing intrinsic static magnetism at high temperatures represent a promising class of multifunctional materials with high application potential in spintronics and magneto-optics. In the hexagonal Fe-doped diluted magnetic oxide, 6H-BaTiO3-δ, room-temperature ferromagnetism has been previously reported. Ferromagnetism is broadly accepted as an intrinsic property of this material, despite its unusual dependence on doping concentration and processing conditions. However, the here reported combination of bulk magnetization and complementary in-depth local-probe electron spin resonance and muon spin relaxation measurements, challenges this conjecture. While a ferromagnetic transition occurs around 700 K, it does so only in additionally annealed samples and is accompanied by an extremely small average value of the ordered magnetic moment. Furthermore, several additional magnetic instabilities are detected at lower temperatures. These coincide with electronic instabilities of the Fe-doped 3C-BaTiO3-δ pseudocubic polymorph. Moreover, the distribution of iron dopants with frozen magnetic moments is found to be non-uniform. Our results demonstrate that the intricate static magnetism of the hexagonal phase is not intrinsic, but rather stems from sparse strain-induced pseudocubic regions. We point out the vital role of internal strain in establishing defect ferromagnetism in systems with competing structural phases. PMID:25572803

Ab initio molecular dynamic study of solid-state transitions of ammonium nitrate

PubMed Central

Yu, Hongyu; Duan, Defang; Liu, Hanyu; Yang, Ting; Tian, Fubo; Bao, Kuo; Li, Da; Zhao, Zhonglong; Liu, Bingbing; Cui, Tian

2016-01-01

High-pressure polymorphism and phase transitions have wide ranging consequences on the basic properties of ammonium nitrate. However, the phase diagram of ammonium nitrate at high pressure and high temperature is still under debate. This study systematically investigates the phase transitions and structural properties of ammonium nitrate at a pressure range of 5–60 GPa and temperature range of 250–400 K by ab initio molecular dynamics simulations. Two new phases are identified: one corresponds to the experimentally observed phase IV’ and the other is named AN-X. Simultaneously, the lattice strains play a significant role in the formation and stabilization of phase IV’, providing a reasonable explanation for experimental observation of phase IV-IV’ transition which only appears under nonhydrostatic pressure. In addition, 12 O atoms neighboring the NH (N atom in ammonium cation) atom are selected as reference system to clearly display the tanglesome rotation of ammonium cation. PMID:26754622

Tetravalent chromium doped laser materials and NIR tunable lasers

NASA Technical Reports Server (NTRS)

Alfano, Robert R. (Inventor); Petricevic, Vladimir (Inventor); Bykov, Alexey (Inventor)

2008-01-01

A method is described to improve and produce purer Cr.sup.4+-doped laser materials and lasers with reduced co-incorporation of chromium in any other valence states, such as Cr.sup.3+, Cr.sup.2+, Cr.sup.5+, and Cr.sup.6+. The method includes: 1) certain crystals of olivine structure with large cation (Ca) in octahedral sites such as Cr.sup.4+:Ca.sub.2GeO.sub.4, Cr.sup.4+:Ca.sub.2SiO.sub.4, Cr.sup.4+:Ca.sub.2Ge.sub.xSi.sub.1-xO.sub.4 (where 0

Age-related macular degeneration-associated silent polymorphisms in HtrA1 impair its ability to antagonize insulin-like growth factor 1.

PubMed

Jacobo, Sarah Melissa P; Deangelis, Margaret M; Kim, Ivana K; Kazlauskas, Andrius

2013-05-01

Synonymous single nucleotide polymorphisms (SNPs) within a transcript's coding region produce no change in the amino acid sequence of the protein product and are therefore intuitively assumed to have a neutral effect on protein function. We report that two common variants of high-temperature requirement A1 (HTRA1) that increase the inherited risk of neovascular age-related macular degeneration (NvAMD) harbor synonymous SNPs within exon 1 of HTRA1 that convert common codons for Ala34 and Gly36 to less frequently used codons. The frequent-to-rare codon conversion reduced the mRNA translation rate and appeared to compromise HtrA1's conformation and function. The protein product generated from the SNP-containing cDNA displayed enhanced susceptibility to proteolysis and a reduced affinity for an anti-HtrA1 antibody. The NvAMD-associated synonymous polymorphisms lie within HtrA1's putative insulin-like growth factor 1 (IGF-1) binding domain. They reduced HtrA1's abilities to associate with IGF-1 and to ameliorate IGF-1-stimulated signaling events and cellular responses. These observations highlight the relevance of synonymous codon usage to protein function and implicate homeostatic protein quality control mechanisms that may go awry in NvAMD.

Infraspecific DNA methylation polymorphism in cotton (Gossypium hirsutum L.).

PubMed

Keyte, Anna L; Percifield, Ryan; Liu, Bao; Wendel, Jonathan F

2006-01-01

Cytosine methylation is important in the epigenetic regulation of gene expression and development in plants and has been implicated in silencing duplicate genes after polyploid formation in several plant groups. Relatively little information exists, however, on levels and patterns of methylation polymorphism (MP) at homologous loci within species. Here we explored the levels and patterns of methylation-polymorphism diversity at CCGG sites within allotetraploid cotton, Gossypium hirsutum, using a methylation-sensitive amplified fragment length polymorphism screen and a selected set of 20 G. hirsutum accessions for which we have information on genetic polymorphism levels and relationships. Methylation and MP exist at high levels within G. hirsutum: of 150 HpaII/MspI sites surveyed, 48 were methylated at the inner cytosine (32%) and 32 of these were polymorphic (67%). Both these values are higher than comparable measures of genetic diversity using restriction fragment length polymorphisms. The high percentage of methylation-polymorphic sites and potential relationship to gene expression underscore the potential significance of MP within and among populations. We speculate that biased correlation of methylation-polymorphic sites and genes in cotton may be a consequence of polyploidy and the attendant doubling of all genes.

Vibrational Properties of Bulk Boric Acid 2A and 3T Polymorphs and Their Two-Dimensional Layers: Measurements and Density Functional Theory Calculations.

PubMed

Bezerra da Silva, M; Santos, R C R; Freire, P T C; Caetano, E W S; Freire, V N

2018-02-08

Boric acid (H 3 BO 3 ) is being used effectively nowadays in traps/baits for the management of Aedes aegypti L. and Aedes albopictus Skuse species of mosquitoes, which are the main spreading vectors worldwide for diseases such as malaria, dengue, and zika. Previously, we published results on the structural, electronic, and optical properties of its molecular triclinic H 3 BO 3 -2A and trigonal H 3 BO 3 -3T polymorphs within the framework of density functional theory (DFT). Because of the renewed importance of these materials, the focus of this work is on the vibrational properties of the bulk boric acid 2A and 3T polymorphs. We measured the infrared and Raman spectra of the former, which was accompanied and interpreted through state-of-the-art DFT calculations, supplemented by computations regarding the H 3 BO 3 molecule and two-dimensional layers based on the bulk structures. We identify/assign their normal modes and find vibrational signatures for each polymorph as well as in- and out-of-plane motions and molecular vibrations, unveiling a nice agreement between the DFT level of theory employed and our improved spectroscopic measurements in the wavenumber ranges of 400-2000 cm -1 (infrared) and 0-1500 cm -1 (Raman). We show that a dispersion-corrected DFT functional within the generalized gradient approximation (GGA) can be very accurate in describing the vibrational properties of the boric acid polymorphs. Besides, several issues left open/not clearly resolved in previously published works on the vibrational mode assignments of the bulk and 2D sheets of boric acid are explained satisfactorily. Finally, phonon dispersions and associated densities of states were also evaluated for each polymorph along with their temperature-dependent DFT-calculated entropy, enthalpy, free energy, heat capacity, and Debye temperature. In particular, our DFT calculations suggest a possible way to differentiate the 2A and 3T boric acid polymorphs through Raman spectroscopy and heat capacity measurements.

Characterization and Thermodynamic Relationship of Three Polymorphs of a Xanthine Oxidase Inhibitor, Febuxostat.

PubMed

Patel, Jinish; Jagia, Moksh; Bansal, Arvind Kumar; Patel, Sarsvatkumar

2015-11-01

Febuxostat (FXT), a xanthine oxidase inhibitor, is an interesting and unique molecule, which exhibits extensive polymorphism, with over 15 polymorphic forms reported to date. The primary purpose of the study was to characterize the three polymorphic forms with respect to their thermodynamic quantities and establish thermodynamic relationship between them. The polymorphs were characterized by thermal and powder X-ray diffraction methods. Three different methods were used to calculate the transition temperatures (Ttr) and thereby their thermodynamic relationships. Although the first and second method used calorimetric data (melting point and heat of fusion), the third method employed the use of configurational free energy phase diagram. The onset melting points of three polymorphic forms were found to be 482.89 ± 0.37 K for form I, 476.30 ± 1.21 K for form II, and 474.19 ± 0.11 K for form III. Moreover, the powder X-ray diffraction patterns for each form were also unique. The polymorphic pair of form I and II and of form I and III was found to be enantiotropic, whereas pair of form II and III was monotropic. Besides the relative thermodynamic aspects (free energy differences, enthalpy, entropy contributions) using different methods, the pharmaceutical implications and phase transformation aspects have also been covered. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Plasminogen Activator Inhibitor-2 Polymorphism Associates with Recurrent Coronary Event Risk in Patients with High HDL and C-Reactive Protein Levels

PubMed Central

Corsetti, James P.; Salzman, Peter; Ryan, Dan; Moss, Arthur J.; Zareba, Wojciech; Sparks, Charles E.

2013-01-01

The objective of this work was to investigate whether fibrinolysis plays a role in establishing recurrent coronary event risk in a previously identified group of postinfarction patients. This group of patients was defined as having concurrently high levels of high-density lipoprotein cholesterol (HDL-C) and C-reactive protein (CRP) and was previously demonstrated to be at high-risk for recurrent coronary events. Potential risk associations of a genetic polymorphism of plasminogen activator inhibitor-2 (PAI-2) were probed as well as potential modulatory effects on such risk of a polymorphism of low-density lipoprotein receptor related protein (LRP-1), a scavenger receptor known to be involved in fibrinolysis in the context of cellular internalization of plasminogen activator/plansminogen activator inhibitor complexes. To this end, Cox multivariable modeling was performed as a function of genetic polymorphisms of PAI-2 (SERPINB, rs6095) and LRP-1 (LRP1, rs1800156) as well as a set of clinical parameters, blood biomarkers, and genetic polymorphisms previously demonstrated to be significantly and independently associated with risk in the study population including cholesteryl ester transfer protein (CETP, rs708272), p22phox (CYBA, rs4673), and thrombospondin-4 (THBS4, rs1866389). Risk association was demonstrated for the reference allele of the PAI-2 polymorphism (hazard ratio 0.41 per allele, 95% CI 0.20-0.84, p=0.014) along with continued significant risk associations for the p22phox and thrombospondin-4 polymorphisms. Additionally, further analysis revealed interaction of the LRP-1 and PAI-2 polymorphisms in generating differential risk that was illustrated using Kaplan-Meier survival analysis. We conclude from the study that fibrinolysis likely plays a role in establishing recurrent coronary risk in postinfarction patients with concurrently high levels of HDL-C and CRP as manifested by differential effects on risk by polymorphisms of several genes linked to key actions involved in the fibrinolytic process. PMID:23874812

Low temperature magneto-morphological characterisation of coronene and the resolution of previously observed unexplained phenomena

NASA Astrophysics Data System (ADS)

Potticary, Jason; Boston, Rebecca; Vella-Zarb, Liana; Few, Alex; Bell, Christopher; Hall, Simon R.

2016-12-01

The polyaromatic hydrocarbon coronene has been the molecule of choice for understanding the physical properties of graphene for over a decade. The modelling of the latter by the former was considered to be valid, as since it was first synthesised in 1932, the physical behaviour of coronene has been determined extremely accurately. We recently discovered however, an unforeseen polymorph of coronene, which exists as an enantiotrope with the previously observed crystal structure. Using low-temperature magnetisation and crystallographic measurements, we show here for the first time that the electronic and magnetic properties of coronene depend directly on the temperature at which it is observed, with hysteretic behaviour exhibited between 300 K and 100 K. Furthermore we determine that this behaviour is a direct result of the appearance and disappearance of the newly-discovered polymorph during thermal cycling. Our results not only highlight the need for theoretical models of graphene to take into account this anomalous behaviour at low temperatures, but also explain puzzling experimental observations of coronene dating back over 40 years.

Natural occurrence and synthesis of two new postspinel polymorphs of chromite.

PubMed

Chen, Ming; Shu, Jinfu; Mao, Ho-kwang; Xie, Xiande; Hemley, Russell J

2003-12-09

A high-pressure polymorph of chromite, the first natural sample with the calcium ferrite structure, has been discovered in the shock veins of the Suizhou meteorite. Synchrotron x-ray diffraction analyses reveal an orthorhombic CaFe2O4-type (CF) structure. The unit-cell parameters are a = 8.954(7) A, b = 2.986(2) A, c = 9.891(7) A, V = 264.5(4) A3 (Z = 4) with space group Pnma. The new phase has a density of 5.62 g/cm3, which is 9.4% denser than chromite-spinel. We performed laser-heated diamond anvil cell experiments to establish that chromite-spinel transforms to CF at 12.5 GPa and then to the recently discovered CaTi2O4-type (CT) structure above 20 GPa. With the ubiquitous presence of chromite, the CF and CT phases may be among the important index minerals for natural transition sequence and pressure and temperature conditions in mantle rocks, shock-metamorphosed terrestrial rocks, and meteorites.

Strong seasonality and interannual recurrence in marine myovirus communities.

PubMed

Pagarete, A; Chow, C-E T; Johannessen, T; Fuhrman, J A; Thingstad, T F; Sandaa, R A

2013-10-01

The temporal community dynamics and persistence of different viral types in the marine environment are still mostly obscure. Polymorphism of the major capsid protein gene, g23, was used to investigate the community composition dynamics of T4-like myoviruses in a North Atlantic fjord for a period of 2 years. A total of 160 unique operational taxonomic units (OTUs) were identified by terminal restriction fragment length polymorphism (TRFLP) of the gene g23. Three major community profiles were identified (winter-spring, summer, and autumn), which resulted in a clear seasonal succession pattern. These seasonal transitions were recurrent over the 2 years and significantly correlated with progression of seawater temperature, Synechococcus abundance, and turbidity. The appearance of the autumn viral communities was concomitant with the occurrence of prominent Synechococcus blooms. As a whole, we found a highly dynamic T4-like viral community with strong seasonality and recurrence patterns. These communities were unexpectedly dominated by a group of persistently abundant viruses.

Study of liquid?liquid demixing from drug solution

NASA Astrophysics Data System (ADS)

Lafferrère, Laurent; Hoff, Christian; Veesler, Stéphane

2004-09-01

In pharmaceutical industry, a deep understanding of the phase diagram is required in design of crystallization processes. We have investigated the phase diagram of a pharmaceutical compound (C 35H 41Cl 2N 3O 2) in a mixture of ethanol/water. This phase diagram exhibits a solid-solid (polymorphism) and a liquid-liquid-phase separation (LLPS) as a function of temperature and drug substance concentration. This study focuses on the LLPS which is metastable with respect to the crystallization of the two polymorphs FI and FII of C 35H 41Cl 2N 3O 2 in an ethanol/water mixture. The LLPS is metastable towards the solubility curve on the whole solvent-solute concentrations and temperature range studied. The LLPS occurred within the metastable zone for crystallization. In our experiments the liquid-liquid-phase transition prevented the drug from crystallizing, while it changed the medium and the conditions of crystallization, which consequently affected the process. The coexistence curves for the liquid phases, also named TL-L boundary, and the spinodal line were measured for a ternary mixture of water-drug-ethanol at atmospheric pressure over a temperature range of 10-50°C. This temperature range corresponds to that used in the crystallization process. Static Light Scattering, HPLC measurements and Karl-Fischer titration were applied to investigate the drug-phase diagram. The isoplethe section of the phase diagram exhibits four regions: one homogeneous (one liquid) and three two-phases (two regions with one liquid+one solid and one region with two liquids), the two solids phases being two polymorphs.

Untangling the roles of microclimate, behaviour and physiological polymorphism in governing vulnerability of intertidal snails to heat stress.

PubMed

Dong, Yun-Wei; Li, Xiao-Xu; Choi, Francis M P; Williams, Gray A; Somero, George N; Helmuth, Brian

2017-05-17

Biogeographic distributions are driven by cumulative effects of smaller scale processes. Thus, vulnerability of animals to thermal stress is the result of physiological sensitivities to body temperature ( T b ), microclimatic conditions, and behavioural thermoregulation. To understand interactions among these variables, we analysed the thermal tolerances of three species of intertidal snails from different latitudes along the Chinese coast, and estimated potential T b in different microhabitats at each site. We then empirically determined the temperatures at which heart rate decreased sharply with rising temperature (Arrhenius breakpoint temperature, ABT) and at which it fell to zero (flat line temperature, FLT) to calculate thermal safety margins (TSM). Regular exceedance of FLT in sun-exposed microhabitats, a lethal effect, was predicted for only one mid-latitude site. However, ABTs of some individuals were exceeded at sun-exposed microhabitats in most sites, suggesting physiological impairment for snails with poor behavioural thermoregulation and revealing inter-individual variations (physiological polymorphism) of thermal limits. An autocorrelation analysis of T b showed that predictability of extreme temperatures was lowest at the hottest sites, indicating that the effectiveness of behavioural thermoregulation is potentially lowest at these sites. These results illustrate the critical roles of mechanistic studies at small spatial scales when predicting effects of climate change. © 2017 The Author(s).

Untangling the roles of microclimate, behaviour and physiological polymorphism in governing vulnerability of intertidal snails to heat stress

PubMed Central

Li, Xiao-xu; Choi, Francis M. P.; Williams, Gray A.; Somero, George N.; Helmuth, Brian

2017-01-01

Biogeographic distributions are driven by cumulative effects of smaller scale processes. Thus, vulnerability of animals to thermal stress is the result of physiological sensitivities to body temperature (Tb), microclimatic conditions, and behavioural thermoregulation. To understand interactions among these variables, we analysed the thermal tolerances of three species of intertidal snails from different latitudes along the Chinese coast, and estimated potential Tb in different microhabitats at each site. We then empirically determined the temperatures at which heart rate decreased sharply with rising temperature (Arrhenius breakpoint temperature, ABT) and at which it fell to zero (flat line temperature, FLT) to calculate thermal safety margins (TSM). Regular exceedance of FLT in sun-exposed microhabitats, a lethal effect, was predicted for only one mid-latitude site. However, ABTs of some individuals were exceeded at sun-exposed microhabitats in most sites, suggesting physiological impairment for snails with poor behavioural thermoregulation and revealing inter-individual variations (physiological polymorphism) of thermal limits. An autocorrelation analysis of Tb showed that predictability of extreme temperatures was lowest at the hottest sites, indicating that the effectiveness of behavioural thermoregulation is potentially lowest at these sites. These results illustrate the critical roles of mechanistic studies at small spatial scales when predicting effects of climate change. PMID:28469014

Phase stability of TiO 2 polymorphs from diffusion Quantum Monte Carlo

DOE PAGES

Luo, Ye; Benali, Anouar; Shulenburger, Luke; ...

2016-11-24

Titanium dioxide, TiO 2, has multiple applications in catalysis, energy conversion and memristive devices because of its electronic structure. Most of applications utilize the naturally existing phases: rutile, anatase and brookite. In spite of the simple form of TiO 2 and its wide uses, there is long- standing disagreement between theory and experiment on the energetic ordering of these phases that has never been resolved. We present the first analysis of phase stability at zero temperature using the highly accurate many-body fixed node diffusion Quantum Monte Carlo (QMC) method. We include temperature effects by calculating the Helmholtz free energy includingmore » both internal energy corrected by QMC and vibrational contributions from phonon calculations within the quasi harmonic approximation via density functional perturbation theory. Our QMC calculations find that anatase is the most stable phase at zero temperature, consistent with many previous mean- field calculations. Furthermore, at elevated temperatures, rutile becomes the most stable phase. For all finite temperatures, brookite is always the least stable phase.« less

Molecular Identification of Date Palm Cultivars Using Random Amplified Polymorphic DNA (RAPD) Markers.

PubMed

Al-Khalifah, Nasser S; Shanavaskhan, A E

2017-01-01

Ambiguity in the total number of date palm cultivars across the world is pointing toward the necessity for an enumerative study using standard morphological and molecular markers. Among molecular markers, DNA markers are more suitable and ubiquitous to most applications. They are highly polymorphic in nature, frequently occurring in genomes, easy to access, and highly reproducible. Various molecular markers such as restriction fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP), simple sequence repeats (SSR), inter-simple sequence repeats (ISSR), and random amplified polymorphic DNA (RAPD) markers have been successfully used as efficient tools for analysis of genetic variation in date palm. This chapter explains a stepwise protocol for extracting total genomic DNA from date palm leaves. A user-friendly protocol for RAPD analysis and a table showing the primers used in different molecular techniques that produce polymorphisms in date palm are also provided.

Genome-wide signatures of flowering adaptation to climate temperature: Regional analyses in a highly diverse native range of Arabidopsis thaliana.

PubMed

Tabas-Madrid, Daniel; Méndez-Vigo, Belén; Arteaga, Noelia; Marcer, Arnald; Pascual-Montano, Alberto; Weigel, Detlef; Xavier Picó, F; Alonso-Blanco, Carlos

2018-03-08

Current global change is fueling an interest to understand the genetic and molecular mechanisms of plant adaptation to climate. In particular, altered flowering time is a common strategy for escape from unfavourable climate temperature. In order to determine the genomic bases underlying flowering time adaptation to this climatic factor, we have systematically analysed a collection of 174 highly diverse Arabidopsis thaliana accessions from the Iberian Peninsula. Analyses of 1.88 million single nucleotide polymorphisms provide evidence for a spatially heterogeneous contribution of demographic and adaptive processes to geographic patterns of genetic variation. Mountains appear to be allele dispersal barriers, whereas the relationship between flowering time and temperature depended on the precise temperature range. Environmental genome-wide associations supported an overall genome adaptation to temperature, with 9.4% of the genes showing significant associations. Furthermore, phenotypic genome-wide associations provided a catalogue of candidate genes underlying flowering time variation. Finally, comparison of environmental and phenotypic genome-wide associations identified known (Twin Sister of FT, FRIGIDA-like 1, and Casein Kinase II Beta chain 1) and new (Epithiospecifer Modifier 1 and Voltage-Dependent Anion Channel 5) genes as candidates for adaptation to climate temperature by altered flowering time. Thus, this regional collection provides an excellent resource to address the spatial complexity of climate adaptation in annual plants. © 2018 John Wiley & Sons Ltd.

Benzocaine polymorphism: pressure-temperature phase diagram involving forms II and III.

PubMed

Gana, Inès; Barrio, Maria; Do, Bernard; Tamarit, Josep-Lluís; Céolin, René; Rietveld, Ivo B

2013-11-18

Understanding the phase behavior of an active pharmaceutical ingredient in a drug formulation is required to avoid the occurrence of sudden phase changes resulting in decrease of bioavailability in a marketed product. Benzocaine is known to possess three crystalline polymorphs, but their stability hierarchy has so far not been determined. A topological method and direct calorimetric measurements under pressure have been used to construct the topological pressure-temperature diagram of the phase relationships between the solid phases II and III, the liquid, and the vapor phase. In the process, the transition temperature between solid phases III and II and its enthalpy change have been determined. Solid phase II, which has the highest melting point, is the more stable phase under ambient conditions in this phase diagram. Surprisingly, solid phase I has not been observed during the study, even though the scarce literature data on its thermal behavior appear to indicate that it might be the most stable one of the three solid phases. Copyright © 2013 Elsevier B.V. All rights reserved.

High Pressure-Temperature Phase Diagram of 1,1-diamino-2,2-dinitroethylene

NASA Astrophysics Data System (ADS)

Bishop, Matthew; Chellappa, Raja; Liu, Zhenxian; Preston, Daniel; Sandstrom, Mary; Dattelbaum, Dana; Vohra, Yogesh; Velisavljevic, Nenad

2013-06-01

1,1-diamino-2,2-dinitroethelyne (FOX-7) is a less sensitive energetic material with performance comparable to commonly used secondary explosives such as RDX and HMX. At ambient pressure, FOX-7 exhibits complex polymorphism with at least three structurally distinct phases (α, β, and γ) . In this study, we have investigated the high P-T stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra confirmed the known α --> β (110 °C) and β --> γ (160 °C) phase transitions; as well as, indicated an additional phase transition, γ --> δ (210°C), with the δ phase being stable up to 250 °C prior to melt/decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa revealed that the α --> β transition occurs at 180 °C, while β --> β + δ phase transition shifted to 300 °C with suppression of γ phase. Decomposition was observed above 325 °C. Based on multiple high P-T measurements, we have established the first high P-T phase diagram of FOX-7. This work was, in part, supported by the US DOE under contract No. DE-AC52-06NA25396 and Science Campaign 2 Program. MB acknowledges additional support from the NSF BD program. Use of NSLS (DE-AC02-98CH10886) beamline U2A (COMPRES, No.EAR01-35554, CDAC).

Highly selective detection of single-nucleotide polymorphisms using a quartz crystal microbalance biosensor based on the toehold-mediated strand displacement reaction.

PubMed

Wang, Dingzhong; Tang, Wei; Wu, Xiaojie; Wang, Xinyi; Chen, Gengjia; Chen, Qiang; Li, Na; Liu, Feng

2012-08-21

Toehold-mediated strand displacement reaction (SDR) is first introduced to develop a simple quartz crystal microbalance (QCM) biosensor without an enzyme or label at normal temperature for highly selective and sensitive detection of single-nucleotide polymorphism (SNP) in the p53 tumor suppressor gene. A hairpin capture probe with an external toehold is designed and immobilized on the gold electrode surface of QCM. A successive SDR is initiated by the target sequence hybridization with the toehold domain and ends with the unfolding of the capture probe. Finally, the open-loop capture probe hybridizes with the streptavidin-coupled reporter probe as an efficient mass amplifier to enhance the QCM signal. The proposed biosensor displays remarkable specificity to target the p53 gene fragment against single-base mutant sequences (e.g., the largest discrimination factor is 63 to C-C mismatch) and high sensitivity with the detection limit of 0.3 nM at 20 °C. As the crucial component of the fabricated biosensor for providing the high discrimination capability, the design rationale of the capture probe is further verified by fluorescence sensing and atomic force microscopy imaging. Additionally, a recovery of 84.1% is obtained when detecting the target sequence in spiked HeLa cells lysate, demonstrating the feasibility of employing this biosensor in detecting SNPs in biological samples.

Dolomite III: A new candidate lower mantle carbonate

NASA Astrophysics Data System (ADS)

Mao, Zhu; Armentrout, Matt; Rainey, Emma; Manning, Craig E.; Dera, Przemyslaw; Prakapenka, Vitali B.; Kavner, Abby

2011-11-01

Dolomite is a major constituent of subducted carbonates; therefore evaluation of its phase stability and equation of state at high pressures and temperatures is important for understanding the deep Earth carbon cycle. X-ray diffraction experiments in the diamond anvil cell show that Ca0.988Mg0.918Fe0.078Mn0.016(CO3)2 dolomite transforms to dolomite-II at ∼17 GPa and 300 K and then upon laser-heating transforms to a new monoclinic phase (dolomite-III), that is observed between 36 and 83 GPa. Both high-pressure polymorphs are stable up to 1500 K, indicating that addition of minor Fe stabilizes dolomite to Earth's deep-mantle conditions.

Multiphase Equations of State for Polymer Materials at High Dynamic Pressures

NASA Astrophysics Data System (ADS)

Khishchenko, Konstantin V.

2015-06-01

Equations of state for materials over a wide range of pressures and temperatures are necessary for numerical simulations of shock-wave processes in condensed matter. Accuracy of calculation results is determined mainly by adequacy of equation of state of a medium. In this work, a new multiphase equation-of-state model is proposed with taking into account the polymorphic phase transformations, melting and evaporation. Thermodynamic calculations are carried out for 2 polymer materials (polymethylmethacrylate and polytetrafluoroethylene) in a broad region of the phase diagram. Obtained results are presented in comparison with available data of experiments at high dynamic pressures in shock and release waves. This work is supported by RSF, Grant 14-50-00124.

Wheat CBF gene family: identification of polymorphisms in the CBF coding sequence.

PubMed

Mohseni, Sara; Che, Hua; Djillali, Zakia; Dumont, Estelle; Nankeu, Joseph; Danyluk, Jean

2012-12-01

Expression of cold-regulated genes needed for protection against freezing stress is mediated, in part, by the CBF transcription factor family. Previous studies with temperate cereals suggested that the CBF gene family in wheat was large, and that CBF genes were at the base of an important low temperature tolerance trait. Therefore, the goal of our study was to identify the CBF repertoire in the freezing-tolerant hexaploid wheat cultivar Norstar, and then to examine if the coding region of CBF genes in two spring cultivars contain polymorphisms that could affect the protein sequence and structure. Our analyses reveal that hexaploid wheat contains a complex CBF family consisting of at least 65 CBF genes of which 60 are known to be expressed in the cultivar Norstar. They represent 27 paralogous genes with 1-3 homeologous copies for the A, B, and D genomes. The cultivar Norstar contains two pseudogenes and at least 24 additional proteins having sequences and (or) structures that deviate from the consensus in the conserved AP2 DNA-binding and (or) C-terminal activation-domains. This suggests that in cultivars such as Norstar, low temperature tolerance may be increased through breeding of additional optimal alleles. The examination of the CBF repertoire present in the two spring cultivars, Chinese Spring and Manitou, reveals that they have additional polymorphisms affecting conserved positions in these domains. Understanding the effects of these polymorphisms will provide additional information for the selection of optimum CBF alleles in Triticeae breeding programs.

Phase Stability of Epsilon and Gamma HNIW (CL-20) at High-Pressure and Temperature

NASA Astrophysics Data System (ADS)

Gump, Jared

2007-06-01

Hexanitrohexaazaisowurtzitane (CL-20) is one of the few ingredients developed since World War II to be considered for transition to military use. Five polymorphs have been identified for CL-20 by FTIR measurements (α, β, γ, ɛ, and ζ). As CL-20 is transitioned into munitions it will become necessary to predict its response under conditions of detonation, for performance evaluation. Such predictive modeling requires a phase diagram and basic thermodynamic properties of the various phases at high pressure and temperature. Theoretical calculations have been performed for a variety of explosive ingredients including CL-20, but it was noted that no experimental measurements existed for comparison with the theoretical bulk modulus calculated for CL-20. Therefore, the phase stabilities of epsilon and gamma CL-20 at static high-pressure and temperature were investigated using synchrotron angle-dispersive x-ray diffraction experiments. The samples were compressed and heated using diamond anvil cells (DAC). Pressures and temperatures achieved were around 5GPa and 175^oC, respectively. No phase change (from the starting epsilon phase) was observed under hydrostatic compression up to 6.3 GPa at ambient temperature. Under ambient pressure the epsilon phase was determined to be stable to a temperature of 120^oC. When heating above 125^oC the gamma phase appeared and it remained stable until thermal decomposition occurred above 150^oC. The gamma phase exhibits a phase change upon compression at both ambient temperature and 140^oC. Pressure -- volume data for the epsilon and gamma phase at ambient temperature and the epsilon phase at 75^oC were fit to the Birch-Murnaghan formalism to obtain isothermal equations of state.

New high-pressure polymorph of In{sub 2}S{sub 3} with defect Th{sub 3}P{sub 4}-type structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Xiaojing; Zhu, Feng; Wu, Ye

The high pressure behavior of β-In{sub 2}S{sub 3} (I4{sub 1}/amd and Z=16) has been studied by in situ synchrotron radiation X-ray diffraction combined with diamond anvil cell up to 71.7 GPa. Three pressure-induced phase transitions are evidenced at ∼6.6 GPa, ∼11.1 GPa at room temperature and 35.6 GPa after the high-temperature annealing using a portable laser heating system. The new polymorph of In{sub 2}S{sub 3} at 35.6 GPa is assigned to the denser cubic defect Th{sub 3}P{sub 4} structure (I4¯3d and Z=5.333), whose unit-cell parameters are a=7.557(1) Å and V=431.6(2) Å{sup 3}. The Th{sub 3}P{sub 4}-type phase can be stablemore » at least up to 71.7 GPa and cannot be preserved at ambient pressure. The pressure–volume relationship is well described by the second-order Birch–Murnaghan Equation of State, which yields B{sub 0}=63(3) GPa and B{sub 0}′=4 (fixed) for the β-In{sub 2}S{sub 3} phase and B{sub 0}=87(3) GPa and B{sub 0}′=4 (fixed) for the defect Th{sub 3}P{sub 4}-type phase respectively. - Graphical abstract: The structure and Rietveld refinement of new polymorph the defect Th{sub 3}P{sub 4}-type In{sub 2}S{sub 3}. This structure was observed at 35.6 GPa after laser heating by X-ray diffraction. Display Omitted - Highlights: Three pressure-induced phase transitions of β-In{sub 2}S{sub 3} were observed. β-In{sub 2}S{sub 3} was stable up to 6.6 GPa. The defect Th{sub 3}P{sub 4}-type In{sub 2}S{sub 3} was identified at 35.6 GPa after laser heating and was stable up to 71.7 GPa. Elastic properties of β-In{sub 2}S{sub 3} and Th{sub 3}P{sub 4}-type In{sub 2}S{sub 3} are well presented by Birch–Murnaghan EoS.« less

Polyimine and its potential significance for prebiotic chemistry on Titan

NASA Astrophysics Data System (ADS)

Rahm, Martin; Lunine, Jonathan I.; Usher, David; Shalloway, David

2016-10-01

Hydrogen cyanide (HCN), a key reagent in prebiotic chemistry, is being generated in large amounts in the atmosphere of Titan. Contradictions between Cassini-Huygens measurements of the atmosphere and the surface of Titan, suggest that HCN is undergoing reaction chemistry, despite the frigid temperatures of 90-94 K. We will discuss computational results [1] investigating polyimine as one potential explanation for this observation. Polyimine is a polymer identified as the major component of polymerized HCN in laboratory experiments. It is flexible, which aids low temperature mobility, and it is able to form intermolecular and intramolecular =N-H...N hydrogen bonds, allowing for different polymorphs. Polymorphs have been predicted and explored by density functional theory coupled with a structure-searching algorithm. We have calculated the thermodynamics of polymerization, and show that polyimine is capable of absorbing light in a window of relative transparency in Titan's atmosphere. Light absorption and the possible catalytic functions of polyimine are suggestive of it driving photochemistry on the surface, with potential prebiotic implications.References:[1] M. Rahm, J. I. Lunine, D. Usher, D. Shalloway, "Polymorphism and electronic structure of polyimine and its potential significance for prebiotic chemistry on Titan", PNAS, early view. doi: 10.1073/pnas.1606634113

What Determines the Ice Polymorph in Clouds?

PubMed

Hudait, Arpa; Molinero, Valeria

2016-07-20

Ice crystals in the atmosphere nucleate from supercooled liquid water and grow by vapor uptake. The structure of the ice polymorph grown has strong impact on the morphology and light scattering of the ice crystals, modulates the amount of water vapor in ice clouds, and can impact the molecular uptake and reactivity of atmospheric aerosols. Experiments and molecular simulations indicate that ice nucleated and grown from deeply supercooled liquid water is metastable stacking disordered ice. The ice polymorph grown from vapor has not yet been determined. Here we use large-scale molecular simulations to determine the structure of ice that grows as a result of uptake of water vapor in the temperature range relevant to cirrus and mixed-phase clouds, elucidate the molecular mechanism of the formation of ice at the vapor interface, and compute the free energy difference between cubic and hexagonal ice interfaces with vapor. We find that vapor deposition results in growth of stacking disordered ice only under conditions of extreme supersaturation, for which a nonequilibrium liquid layer completely wets the surface of ice. Such extreme conditions have been used to produce stacking disordered frost ice in experiments and may be plausible in the summer polar mesosphere. Growth of ice from vapor at moderate supersaturations in the temperature range relevant to cirrus and mixed-phase clouds, from 200 to 260 K, produces exclusively the stable hexagonal ice polymorph. Cubic ice is disfavored with respect to hexagonal ice not only by a small penalty in the bulk free energy (3.6 ± 1.5 J mol(-1) at 260 K) but also by a large free energy penalty at the ice-vapor interface (89.7 ± 12.8 J mol(-1) at 260 K). The latter originates in higher vibrational entropy of the hexagonal-terminated ice-vapor interface. We predict that the free energy penalty against the cubic ice interface should decrease strongly with temperature, resulting in some degree of stacking disorder in ice grown from vapor in the tropical tropopause layer, and in polar stratospheric and noctilucent clouds. Our findings support and explain the evolution of the morphology of ice crystals from hexagonal to trigonal symmetry with decreasing temperature, as reported by experiments and in situ measurements in clouds. We conclude that selective growth of the elusive cubic ice polymorph by manipulation of the interfacial properties can likely be achieved at the ice-liquid interface but not at the ice-vapor interface.

Polymorphism and Superconductivity in Bilayer Molecular Metals (CNB-EDT-TTF)4I3.

PubMed

Rabaça, Sandra; Oliveira, Sandrina; Santos, Isabel C; Gama, Vasco; Belo, Dulce; Lopes, Elsa B; Canadell, Enric; Almeida, Manuel

2016-10-17

Electrocrystallization from solutions of the dissymmetrical ET derivative cyanobenzene-ethylenedithio-tetrathiafulvalene (CNB-EDT-TTF) in the presence of triiodide I 3 - affords two different polymorphs (β″ and κ) with the composition (CNB-EDT-TTF) 4 I 3 , both with a bilayer structure of the donors. These polymorphs differ in the packing patterns (β″- and κ-type) of the donor molecules in each layer, in both cases with bifurcated C-N···H interactions effectively coupling head-to-head donor molecules between layer pairs. Two β″ polymorphs can be obtained with different degrees of anionic ordering. In one disordered phase, β″ d , with a smaller unit cell, the triiodide anions are disordered over two possible positions in a channel between the donor bilayers, while in the ordered phase, β″ o , the triiodide anions occupy only one of those positions in this channel, leading to the doubling of the unit cell in the layer plane. These results for β″ phases contrast with the κ polymorph previously reported, for which weaker disorder of the triiodide anions, over two possible orientations with 94 and 6% occupation factors, was observed. While the β″ polymorphs remains metallic down to 1.5 K with a ρ 300K /ρ 4K resistivity ratio of 250, the κ polymorph presents a much smaller resistivity ratio in the range of 4-10 and superconductivity with an onset temperature of 3.5 K.

Polytypism, polymorphism, and superconductivity in TaSe 2 –xTe x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Huixia; Xie, Weiwei; Tao, Jing

2015-03-03

Polymorphism in materials often leads to significantly different physical properties - the rutile and anatase polymorphs of TiO₂ are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivitymore » of TaSe₂, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access 2 stable polytypes and 2 stable polymorphs in the TaSe 2-xTe x solid solution, and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. Thus, the reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of T c on subtle differences in the characteristics of the single layers present, or from a surprising effect of the layer stacking sequence on electronic properties that instead are expected to be dominated by the properties of a single layer in materials of this kind.« less

Competitive stereocomplexation, homocrystallization, and polymorphic crystalline transition in poly(L-lactic acid)/poly(D-lactic acid) racemic blends: molecular weight effects.

PubMed

Pan, Pengju; Han, Lili; Bao, Jianna; Xie, Qing; Shan, Guorong; Bao, Yongzhong

2015-05-28

Competitive crystallization kinetics, polymorphic crystalline structure, and transition of poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic blends with a wide range of molecular weights (MWs) were symmetrically investigated. Stereocomplex (sc) crystallites are exclusively formed in the low-MW racemic blends. However, stereocomplexation is remarkably depressed, and homocrystallization becomes prevailing with increasing MWs of PLLA and PDLA. Suppressed stereocomplexation in high-MW (HMW) racemic blends is proposed to be due to the low chain diffusion ability and restricted intermolecular crystal nucleation/growth. Equilibrium melting point of sc crystallites first increases and then decreases as MW increases. Crystallinity and relative fraction of sc crystallites in racemic blends enhance with crystallization temperature (Tc), and the sc crystallites are merely formed at Tc > 170 °C because of their higher thermodynamic stability. In situ wide-angle X-ray diffraction (WAXD) analysis reveals that the stereocomplexation and homocrystallization are successive rather than completely simultaneous, and the stereocomplexation is preceding homocrystallization in isothermal crystallization of HMW racemic blends. Both initial crystalline structure of homocrystallites (hc) and MW influence the heating-induced hc-to-sc transition of HMW racemic blend drastically; the hc-to-sc transition becomes easier with decreasing Tc and MW. After crystallization at the same temperature, sc crystallites show smaller long period than their hc counterparts.

West Nile Virus Temperature Sensitivity and Avian Virulence Are Modulated by NS1-2B Polymorphisms.

PubMed

Dietrich, Elizabeth A; Langevin, Stanley A; Huang, Claire Y-H; Maharaj, Payal D; Delorey, Mark J; Bowen, Richard A; Kinney, Richard M; Brault, Aaron C

2016-08-01

West Nile virus (WNV) replicates in a wide variety of avian species, which serve as reservoir and amplification hosts. WNV strains isolated in North America, such as the prototype strain NY99, elicit a highly pathogenic response in certain avian species, notably American crows (AMCRs; Corvus brachyrhynchos). In contrast, a closely related strain, KN3829, isolated in Kenya, exhibits a low viremic response with limited mortality in AMCRs. Previous work has associated the difference in pathogenicity primarily with a single amino acid mutation at position 249 in the helicase domain of the NS3 protein. The NY99 strain encodes a proline residue at this position, while KN3829 encodes a threonine. Introduction of an NS3-T249P mutation in the KN3829 genetic background significantly increased virulence and mortality; however, peak viremia and mortality were lower than those of NY99. In order to elucidate the viral genetic basis for phenotype variations exclusive of the NS3-249 polymorphism, chimeric NY99/KN3829 viruses were created. We show herein that differences in the NS1-2B region contribute to avian pathogenicity in a manner that is independent of and additive with the NS3-249 mutation. Additionally, NS1-2B residues were found to alter temperature sensitivity when grown in avian cells.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brgoch, Jakoah; Klob, Simon D.; Denault, Kristin A.

The preparation of Eu 2+-substituted barium aluminum silicates is achieved using a rapid microwave-assisted preparation. The phase evolution of two BaAl 2Si 2O 8:Eu 2+ polymorphs, the higher temperature hexagonal phase (hexacelsian), and the lower temperature monoclinic phase (celsian), is explored by varying the ramp time and soak time. This preparation method significantly reduces the reaction time needed to form these phases compared to conventional solid state routes. The luminescent properties of the two phases are identified under UV excitation with the hexagonal phase emitting in the UV region (λ em = 372 nm) and the monoclinic phase emitting inmore » the blue region (λ em = 438 nm). The differences in optical properties of the two polymorphs are correlated to the coordination number and arrangement of the alkali earth site. The optical properties of the monoclinic phase can be further tuned through the substitution of Sr 2+, forming the solid solution (Ba 1–xSr x)Al 2Si 2O 8:Eu 2+. Changes in the crystal structure due to Sr 2+ substitution produce a surprising blue-shift in the emission spectrum, which is explained by a greater dispersion of bond lengths in the (Ba/Sr)–O polyhedra. The entire monoclinic solid solution exhibits excellent quantum yields of nearly 90 %, owing to the structural rigidity provided by the highly connected tetrahedral network.« less

High pressure–temperature phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, Matthew M.; Velisavljevic, Nenad; Chellappa, Raja

In this study, the pressure–temperature (P–T) phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7) was determined by in situ synchrotron infrared radiation spectroscopy with the resistively heated diamond anvil cell (DAC) technique. The stability of high-P–T FOX-7 polymorphs is established from ambient pressure up to 10 GPa and temperatures until decomposition. The phase diagram indicates two near isobaric phase boundaries at ~2 GPa (α → I) and ~5 GPa (I → II) that persists from 25 °C until the onset of decomposition at ~300 °C. In addition, the ambient pressure, high-temperature α → β phase transition (~111 °C) lies along a steep boundarymore » (~100 °C/GPa) with a α–β–δ triple point at ~1 GPa and 300 °C. A 0.9 GPa isobaric temperature ramping measurement indicates a limited stability range for the γ-phase between 0.5 and 0.9 GPa and 180 and 260 °C, terminating in a β–γ–δ triple point. With increasing pressure, the δ-phase exhibited a small negative dT/dP slope (up to ~0.2 GPa) before turning over to a positive 70 °C/GPa slope, at higher pressures. The decomposition boundary (~55 °C/GPa) was identified through the emergence of spectroscopic signatures of the characteristic decomposition products as well as trapped inclusions within the solid KBr pressure media.« less

High pressure–temperature phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7)

DOE PAGES

Bishop, Matthew M.; Velisavljevic, Nenad; Chellappa, Raja; ...

2015-08-27

In this study, the pressure–temperature (P–T) phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7) was determined by in situ synchrotron infrared radiation spectroscopy with the resistively heated diamond anvil cell (DAC) technique. The stability of high-P–T FOX-7 polymorphs is established from ambient pressure up to 10 GPa and temperatures until decomposition. The phase diagram indicates two near isobaric phase boundaries at ~2 GPa (α → I) and ~5 GPa (I → II) that persists from 25 °C until the onset of decomposition at ~300 °C. In addition, the ambient pressure, high-temperature α → β phase transition (~111 °C) lies along a steep boundarymore » (~100 °C/GPa) with a α–β–δ triple point at ~1 GPa and 300 °C. A 0.9 GPa isobaric temperature ramping measurement indicates a limited stability range for the γ-phase between 0.5 and 0.9 GPa and 180 and 260 °C, terminating in a β–γ–δ triple point. With increasing pressure, the δ-phase exhibited a small negative dT/dP slope (up to ~0.2 GPa) before turning over to a positive 70 °C/GPa slope, at higher pressures. The decomposition boundary (~55 °C/GPa) was identified through the emergence of spectroscopic signatures of the characteristic decomposition products as well as trapped inclusions within the solid KBr pressure media.« less

Temperature and rate of dehydration of major constituents of carbonaceous chondrites under vacuum conditions

NASA Astrophysics Data System (ADS)

Pohl, Leos; Britt, Daniel

2017-10-01

Some sub-types of carbonaceous chondrites contain a significant amount of hydrated minerals which produce specific absorption lines, typically due to the presence of hydroxyls. However, if these asteroids have come close enough to the Sun during their history, the high temperatures might have resulted in mineral decomposition and consequent loss of hydroxyl (or water) molecules in the surface layer and even to certain depths. Determination of the hydration state of phyllosilicates typically found on asteroids as well as the relative quantities of hydrated to desiccated phyllosilicates relies on experimental data - the temperature and rate of dehydration. Both dehydration temperature and rate depend on pressure. The rate also depends on the temperature. Experimentally determined phase curves for serpentine, that show for example decomposition of antigorite to forsterite and enstatite or talc and water, exist for GPa pressure levels. For antigorite, these temperatures span the range 500-750°C for pressures between 0.1 GPa and 8 GPa. However, these data are not suitable for vacuum environment found on asteroids; further, at lower pressures, the available data suggest a monotonically decreasing dehydration temperature with decreasing pressure. Also, the available data suggest dependence of both dehydration temperature and rate on the grain size distribution of the mineral. We have determined the temperature and rate of dehydration of the serpentine polymorphs antigorite, lizardite, cronstedtite, under high vacuum conditions and for various grain size distributions. The grain size distributions have been determined by particle analyzer and each sample source was also analyzed using X-Ray Diffraction.

Hydrothermal Signatures at Gale Crater, Mars, and Possible In-Situ Formation of Tridymite

NASA Astrophysics Data System (ADS)

Yen, A. S.; Morris, R. V.; Gellert, R.; Berger, J. A.; Sutter, B.; Downs, R. T.; Bristow, T.; Treiman, A. H.; Ming, D. W.; Achilles, C.; Blake, D. F.; Chipera, S.; Clark, B. C.; Craig, P.; Morrison, S. M.; Rampe, E. B.; Schmidt, M. E.; Schwenzer, S. P.; Thompson, L. M.; Vaniman, D.

2017-12-01

The occurrence of tridymite, a high temperature SiO2 polymorph definitively identified by the Curiosity rover in the Buckskin mudstone sample at Gale crater, Mars, has been attributed to detrital accumulation of rhyolitic material. This interpretation of a detrital origin is revisited in light of the observation that the tridymite-hosting sediments appear to have interacted with the same fluids that produced alteration halos in the overlying sandstone. The alteration halos in the Stimson sandstone are light-toned, elevated silica zones within 50 cm of a central fracture. They have likely experienced chemical leaching under acidic conditions resulting in depletion of metals (including Al), retention of Ti, formation of amorphous iron sulfates, 50% reduction of the pyroxene:plagioclase ratio, a factor of two increase in the Fe/Mn ratio, and passive enrichment of Si. This alteration is not constrained (nor precluded) to have occurred at elevated temperatures, but there are abundant indicators of hydrothermal activity within Gale crater. High concentrations of Ge, Zn, Ni, Pb, Cu, Se and Ga in a variety of samples analyzed by the Alpha Particle X-ray Spectrometer are indicative of mobility in hydrothermal solutions. Mineralogy of Gale crater samples determined by the CheMin X-ray diffraction instrument includes phases which may be associated with hydrothermal activity (smectites, anhydrite, hematite), but definitive detections of mineral assemblages that are necessarily hydrothermal in origin remain absent. The nearly identical patterns of enriched and depleted elements of the Stimson alteration halos (relative to parent rocks) and the tridymite-bearing unit (relative to typical mudstone samples) require the consideration of co-genetic origins. Cristobalite, a SiO2 polymorph stable above 1470°C found in the Buckskin sample, is known to form in hydrothermal solutions at temperatures well below its stability field (Henderson et al., 1971). Formation of well-crystalline tridymite at temperatures below its thermodynamic stability range (870-1470°C) has not been established, but cannot be excluded. Thus, the possibility that the fluids responsible for the passive enrichment of silica in the Stimson alteration halos also resulted in the in-situ formation of tridymite deserves further consideration.

Phase stability of iron germanate, FeGeO 3, to 127 GPa

DOE PAGES

Dutta, R.; Tracy, S. J.; Stan, C. V.; ...

2017-11-15

The high-pressure behavior of germanates is of interest as these compounds serve as analogs for silicates of the deep Earth. Current theoretical and experimental studies of iron germanate, FeGeO 3, are limited. Here in this paper, we have examined the behavior of FeGeO 3 to 127 GPa using the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. Upon compression at room temperature, the ambient-pressure clinopyroxene phase transforms to a disordered triclinic phase [FeGeO 3 (II)] at ~ 18 GPa in agreement with earlier studies. An additional phase transition to FeGeO 3 (III) occurs above 54 GPa atmore » room temperature. Laser-heating experiments (~ 1200–2200 K) were conducted at three pressures (33, 54, and 123 GPa) chosen to cover the stability regions of different GeO 2 polymorphs. In all cases, we observe that FeGeO 3 dissociates into GeO 2 + FeO at high pressure and temperature conditions. Neither the perovskite nor the post-perovskite phase was observed up to 127 GPa at ambient or high temperatures. The results are consistent with the behavior of FeSiO 3, which also dissociates into a mixture of the oxides (FeO + SiO 2) at least up to 149 GPa.« less

Genetic polymorphisms in the amino acid transporters LAT1 and LAT2 in relation to the pharmacokinetics and side effects of melphalan.

PubMed

Kühne, Annett; Kaiser, Rolf; Schirmer, Markus; Heider, Ulrike; Muhlke, Sabine; Niere, Wiebke; Overbeck, Tobias; Hohloch, Karin; Trümper, Lorenz; Sezer, Orhan; Brockmöller, Jürgen

2007-07-01

Melphalan is widely used in the treatment of multiple myeloma. Pharmacokinetics of this alkylating drug shows high inter-individual variability. As melphalan is a phenylalanine derivative, the pharmacokinetic variability may be determined by genetic polymorphisms in the L-type amino acid transporters LAT1 (SLC7A5) and LAT2 (SLC7A8). Pharmacokinetics were analysed in 64 patients after first administration of intravenous melphalan. Severity of side effects was documented according to WHO criteria. Genomic DNA was analysed for polymorphisms in LAT1 and LAT2 by sequencing of the entire coding region, intron-exon boundaries and 2 kb upstream promoter region. Selected polymorphisms in the common heavy chain of both transporters, the protein 4F2hc (SLC3A2), were analysed by single nucleotide primer extension. Melphalan pharmacokinetics was highly variable with up to 6.2-fold differences in total clearance. A total of 44 polymorphisms were identified in LAT1 and 21 polymorphisms in LAT2. From all variants, only five were in the coding region and only one heterozygous non-synonymous polymorphism (Ala94Thr) was found in LAT2. Numerous polymorphisms were found in the LAT1 and LAT2 5'-flanking regions but did not correlate with expression of the respective genes. No significant correlations could be observed between the polymorphisms in 4F2hc, LAT1, and LAT2 with melphalan pharmacokinetics or with melphalan side effects. The study confirmed that these transporter genes are highly conserved, particularly in the coding sequences. Genetic variation in 4F2hc, LAT1, and LAT2 does not appear to be a major cause of inter-individual variability in pharmacokinetics and of adverse reactions to melphalan.

Polymorphism of phosphoric oxide

USGS Publications Warehouse

Hill, W.L.; Faust, G.T.; Hendricks, S.B.

1943-01-01

The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

Crystallization of a salt of a weak organic acid and base: solubility relations, supersaturation control and polymorphic behavior.

PubMed

Jones, H P; Davey, R J; Cox, B G

2005-03-24

Control of crystallization processes for organic salts is of importance to the pharmaceutical industry as many active pharmaceutical materials are marketed as salts. In this study, a method for estimating the solubility product of a salt of a weak acid and weak base from measured pH-solubility data is described for the first time. This allows calculation of the supersaturation of solutions at known pH. Ethylenediammonium 3,5-dinitrobenzoate is a polymorphic organic salt. A detailed study of the effects of pH, supersaturation, and temperature of crystallization on the physical properties of this salt shows that the desired polymorph may be produced by appropriate selection of the pH and supersaturation of crystallization. Crystal morphology is also controlled by these crystallization conditions.

Genetic polymorphisms of PPAR gamma, arsenic methylation capacity and breast cancer risk in Mexican women.

PubMed

Pineda-Belmontes, Cristina P; Hernández-Ramírez, Raúl U; Hernández-Alcaraz, César; Cebrián, Mariano E; López-Carrillo, Lizbeth

2016-04-01

To evaluate whether the presence of polymorphisms of peroxisome proliferator-activated receptor gamma PPARγ (Pro 1 2Ala) and PPARGC1B (Ala203Pro) modifies the association between the inorganic arsenic (iAs) methylation capacity and breast cancer (BC). Mexican women were interviewed, and blood and urine samples were collected from them (cases/controls= 197/220). The concentration of urinary arsenic species and the polymorphisms of interest were determined by high-performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and polymerase chain reaction (PCR), respectively. In women with a high %MMA (urinary monomethyl arsenic) and high primary methylation ratio (PM = MMA/iAs), the risk of BC was increased (odds ratio [OR]%MMA T3 vs.T1= 3.60: 95% confidence interval [CI] 2.02-6.41, ORPMI T3 vs.T1= 3.47: 95%CI 1.95-6.17), which was maintained after adjusting for polymorphisms. No significant interactions were observed between the polymorphisms and the arsenic variables on the risk of BC. Pro 12Ala and Ala203Pro polymorphisms did not modify the association between the iAs methylation capacity and BC.

HTRA1 promoter polymorphism predisposes Japanese to age-related macular degeneration.

PubMed

Yoshida, Tsunehiko; DeWan, Andrew; Zhang, Hong; Sakamoto, Ryosuke; Okamoto, Haru; Minami, Masayoshi; Obazawa, Minoru; Mizota, Atsushi; Tanaka, Minoru; Saito, Yoshihiro; Takagi, Ikue; Hoh, Josephine; Iwata, Takeshi

2007-04-04

To study the effect of candidate single nucleotide polymorphisms (SNPs) on chromosome 10q26, recently shown to be associated with wet age-related macular degeneration (AMD) in Chinese and Caucasian cohorts, in a Japanese cohort. Using genomic DNA isolated from peripheral blood of wet AMD cases and age-matched controls, we genotyped two SNPs, rs10490924, and rs11200638, on chromosome 10q26, 6.6 kb and 512 bp upstream of the HTRA1 gene, respectively, using temperature gradient capillary electrophoresis (TGCE) and direct sequencing. Association tests were performed for individual SNPs and jointly with SNP complement factor H (CFH) Y402H. The two SNPs, rs10490924 and rs11200638, are in complete linkage disequilibrium (D'=1). Previous sequence comparisons among seventeen species revealed that the genomic region containing rs11200638 was highly conserved while the region surrounding rs10490924 was not. The allelic association test for rs11200638 yielded a p-value <10(-11). SNP rs11200638 conferred disease risk in an autosomal recessive fashion: Odds ratio was 10.1 (95% CI 4.36, 23.06), adjusted for SNP CFH 402, for those carrying two copies of the risk allele, whereas indistinguishable from unity if carrying only one risk allele. The HTRA1 promoter polymorphism, rs11200638, is a strong candidate with a functional consequence that predisposes Japanese to develop neovascular AMD.

Surface chemistry and reactivity of SiO2 polymorphs: A comparative study on α-quartz and α-cristobalite

NASA Astrophysics Data System (ADS)

Tang, Cuihua; Zhu, Jianxi; Li, Zhaohui; Zhu, Runliang; Zhou, Qing; Wei, Jingming; He, Hongping; Tao, Qi

2015-11-01

Silica minerals are widely used in environmental remediation for their prevalence in soil and sediment. Two common SiO2 polymorphs, α-quartz and α-cristobalite, were investigated for the removal of a typical cationic dye, methylene blue (MB), from aqueous solutions. Their adsorption behaviors were studied in batch experiments as a function of specific surface area (SSA), pH, and temperature. The surface site density of α-quartz (10.6 sites/nm2) was higher than that of α-cristobalite (6.2 sites/nm2) with the Gran plot method, and the adsorption maxima of MB on the two were 0.84 mg/m2 and 0.49 mg/m2, respectively, at 303 K and pH 8. The potentiometric titration showed the capacity of proton-donating by α-quartz was stronger than that by α-cristobalite. A drastic increase of adsorption amount on α-quartz at pH < 3 was caused by its greater quantity of isolated silanols. The negative ΔG and positive ΔH values suggested adsorption of MB on both minerals was spontaneous and endothermic. At three different temperatures (288 K, 298 K, and 303 K), the adsorption capacities of two polymorphs increased with increasing temperature. The surface heterogeneity of α-quartz and α-cristobalite corresponds to their different adsorption behavior, and our work also provides some referential significance in evaluating the overall quality of soils and sediments.

Electron petrography of silica polymorphs associated with pseudotachylite, Vredefort structure, South Africa

NASA Technical Reports Server (NTRS)

White, J. C.

1992-01-01

High-pressure silica polymorphs (coesite and stishovite) were described from the Vredefort structure in association with pseudotachylite veinlets. In addition to the fundamental significance of the polymorphs to genetic interpretations of the structure, it was additionally argued that the type of pseudotachylite with which they occur forms during the compressional phase of the shock process, while the larger, classic pseudotachylite occurrences are barren of polymorphs and formed during passage of the rarefaction wave. This identification of temporal relationships among transient shock features at a regional scale is similar to observations from the Manicouagan structure, Quebec, where texturally distinct diaplectic plagioclase glasses formed during both compressional and decompressional phases of the shock process. The clarification of such relationships impinges directly on interpretations of natural shock processes and the identification of high probability targets for polymorph searches. Detailed analytical scanning (SEM) and transmission electron microscopy (TEM) were utilized to further establish the nature of both the pseudotachylite and the silica polymorph occurrences in the Vredefort rocks. The results of this investigation are discussed.

Characterization of Novel Gene Yr79 and Four Additional Quantitative Trait Loci for All-Stage and High-Temperature Adult-Plant Resistance to Stripe Rust in Spring Wheat PI 182103.

PubMed

Feng, Junyan; Wang, Meinan; See, Deven R; Chao, Shiaoman; Zheng, Youliang; Chen, Xianming

2018-06-01

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important disease of wheat worldwide. Exploring new resistance genes is essential for breeding resistant wheat cultivars. PI 182103, a spring wheat landrace originally from Pakistan, has shown a high level of resistance to stripe rust in fields for many years, but genes for resistance to stripe rust in the variety have not been studied. To map the resistance gene(s) in PI 182103, 185 recombinant inbred lines (RILs) were developed from a cross with Avocet Susceptible (AvS). The RIL population was genotyped with simple sequence repeat (SSR) and single nucleotide polymorphism markers and tested with races PST-100 and PST-114 at the seedling stage under controlled greenhouse conditions and at the adult-plant stage in fields at Pullman and Mt. Vernon, Washington under natural infection by the stripe rust pathogen in 2011, 2012, and 2013. A total of five quantitative trait loci (QTL) were detected. QyrPI182103.wgp-2AS and QyrPI182103.wgp-3AL were detected at the seedling stage, QyrPI182103.wgp-4DL was detected only in Mt. Vernon field tests, and QyrPI182103.wgp-5BS was detected in both seedling and field tests. QyrPI182103.wgp-7BL was identified as a high-temperature adult-plant resistance gene and detected in all field tests. Interactions among the QTL were mostly additive, but some negative interactions were detected. The 7BL QTL was mapped in chromosomal bin 7BL 0.40 to 0.45 and identified as a new gene, permanently designated as Yr79. SSR markers Xbarc72 and Xwmc335 flanking the Yr79 locus were highly polymorphic in various wheat genotypes, indicating that the molecular markers are useful for incorporating the new gene for potentially durable stripe rust resistance into new wheat cultivars.

A flow-free droplet-based device for high throughput polymorphic crystallization.

PubMed

Yang, Shih-Mo; Zhang, Dapeng; Chen, Wang; Chen, Shih-Chi

2015-06-21

Crystallization is one of the most crucial steps in the process of pharmaceutical formulation. In recent years, emulsion-based platforms have been developed and broadly adopted to generate high quality products. However, these conventional approaches such as stirring are still limited in several aspects, e.g., unstable crystallization conditions and broad size distribution; besides, only simple crystal forms can be produced. In this paper, we present a new flow-free droplet-based formation process for producing highly controlled crystallization with two examples: (1) NaCl crystallization reveals the ability to package saturated solution into nanoliter droplets, and (2) glycine crystallization demonstrates the ability to produce polymorphic crystallization forms by controlling the droplet size and temperature. In our process, the saturated solution automatically fills the microwell array powered by degassed bulk PDMS. A critical oil covering step is then introduced to isolate the saturated solution and control the water dissolution rate. Utilizing surface tension, the solution is uniformly packaged in the form of thousands of isolating droplets at the bottom of each microwell of 50-300 μm diameter. After water dissolution, individual crystal structures are automatically formed inside the microwell array. This approach facilitates the study of different glycine growth processes: α-form generated inside the droplets and γ-form generated at the edge of the droplets. With precise temperature control over nanoliter-sized droplets, the growth of ellipsoidal crystalline agglomerates of glycine was achieved for the first time. Optical and SEM images illustrate that the ellipsoidal agglomerates consist of 2-5 μm glycine clusters with inner spiral structures of ~35 μm screw pitch. Lastly, the size distribution of spherical crystalline agglomerates (SAs) produced from microwells of different sizes was measured to have a coefficient variation (CV) of less than 5%, showing crystal sizes can be precisely controlled by microwell sizes with high uniformity. This new method can be used to reliably fabricate monodispersed crystals for pharmaceutical applications.

Polymorphous computing fabric

DOEpatents

Wolinski, Christophe Czeslaw [Los Alamos, NM; Gokhale, Maya B [Los Alamos, NM; McCabe, Kevin Peter [Los Alamos, NM

2011-01-18

Fabric-based computing systems and methods are disclosed. A fabric-based computing system can include a polymorphous computing fabric that can be customized on a per application basis and a host processor in communication with said polymorphous computing fabric. The polymorphous computing fabric includes a cellular architecture that can be highly parameterized to enable a customized synthesis of fabric instances for a variety of enhanced application performances thereof. A global memory concept can also be included that provides the host processor random access to all variables and instructions associated with the polymorphous computing fabric.

A Novel Small Heat Shock Protein Gene, vis1, Contributes to Pectin Depolymerization and Juice Viscosity in Tomato Fruit1

PubMed Central

Ramakrishna, Wusirika; Deng, Zhiping; Ding, Chang-Kui; Handa, Avtar K.; Ozminkowski, Richard H.

2003-01-01

We have characterized a novel small heat shock protein gene, viscosity 1 (vis1) from tomato (Lycopersicon esculentum) and provide evidence that it plays a role in pectin depolymerization and juice viscosity in ripening fruits. Expression of vis1 is negatively associated with juice viscosity in diverse tomato genotypes. vis1 exhibits DNA polymorphism among tomato genotypes, and the alleles vis1-hta (high-transcript accumulator; accession no. AY128101) and vis1-lta (low transcript accumulator; accession no. AY128102) are associated with thinner and thicker juice, respectively. Segregation of tomato lines heterogeneous for vis1 alleles indicates that vis1 influences pectin depolymerization and juice viscosity in ripening fruits. vis1 is regulated by fruit ripening and high temperature and exhibits a typical heat shock protein chaperone function when expressed in bacterial cells. We propose that VIS1 contributes to physiochemical properties of juice, including pectin depolymerization, by reducing thermal denaturation of depolymerizing enzymes during daytime elevated temperatures. PMID:12586896

Rotor-stator molecular crystals of fullerenes with cubane.

PubMed

Pekker, Sándor; Kováts, Eva; Oszlányi, Gábor; Bényei, Gyula; Klupp, Gyöngyi; Bortel, Gábor; Jalsovszky, István; Jakab, Emma; Borondics, Ferenc; Kamarás, Katalin; Bokor, Mónika; Kriza, György; Tompa, Kálmán; Faigel, Gyula

2005-10-01

Cubane (C8H8) and fullerene (C60) are famous cage molecules with shapes of platonic or archimedean solids. Their remarkable chemical and solid-state properties have induced great scientific interest. Both materials form polymorphic crystals of molecules with variable orientational ordering. The idea of intercalating fullerene with cubane was raised several years ago but no attempts at preparation have been reported. Here we show that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane. Static cubane occupies the octahedral voids of the face-centred-cubic structures and acts as a bearing between the rotating fullerene molecules. The smooth contact of the rotor and stator molecules decreases significantly the temperature of orientational ordering. These materials have great topochemical importance: at elevated temperatures they transform to high-stability covalent derivatives although preserving their crystalline appearance. The size-dependent molecular recognition promises selective formation of related structures with higher fullerenes and/or substituted cubanes.

Packing Polymorphism of Dapivirine and Its Impact on the Performance of a Dapivirine-Releasing Silicone Elastomer Vaginal Ring.

PubMed

McCoy, Clare F; Murphy, Diarmaid J; Boyd, Peter; Derrick, Tiffany; Spence, Patrick; Devlin, Brid; Malcolm, R Karl

2017-08-01

A silicone elastomer vaginal ring providing sustained release over 28 days of the anti-retroviral microbicide dapivirine has recently completed phase III clinical testing and showed moderate protection against HIV acquisition. In support of the product licensure program, we report the impact of dapivirine packing polymorphism on the thermal and solubility characteristics of dapivirine and on the in vitro performance of the 25 mg dapivirine ring product. This is the first time that polymorphism has been reported for a drug-releasing vaginal ring product. Thermal, particle size, powder X-ray diffraction, and thermodynamic solubility analyses of dapivirine polymorphic forms I and IV, both of which are persistent at room temperature and with form I being the thermodynamically stable form, were conducted for both micronized and non-micronized materials. No significant differences in solubility between DPV forms I and IV were observed in media commonly used for in vitro release testing. Matrix-type silicone elastomer vaginal rings were manufactured and the impact of dapivirine polymorphism on key in vitro parameters (compression and tensile behavior; content assay; in vitro release; residual content assay) was investigated. The data demonstrate that dapivirine packing polymorphism has no significant impact on in vitro performance of the 25 mg dapivirine vaginal ring. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Computational and experimental studies of iron-bearing carbonates and silicate glasses at lower mantle pressures

NASA Astrophysics Data System (ADS)

Solomatova, N. V.; Jackson, J. M.; Asimow, P. D.; Sturhahn, W.; Rossman, G. R.; Roskosz, M.

2017-12-01

Decomposition of carbonates may be responsible for creating silicate melts within the lower mantle by lowering the melting temperature of surrounding rock. Identifying and characterizing the stability of carbonates is therefore a necessary step towards understanding the transport of carbon in Earth's interior. Dolomite is one of the major mineral forms in which carbon is subducted into the Earth's mantle. Although iron-free dolomite is expected to break down upon compression, high-pressure polymorphs of iron-bearing dolomite may resist decomposition. Using a genetic algorithm that predicts crystal structures, we found a monoclinic phase with space group C2/c that has a lower energy than all previously reported dolomite structures at pressures above 15 GPa, where the substitution of iron for magnesium stabilizes monoclinic dolomite at certain pressures of the lower mantle. Thus, an iron-bearing dolomite polymorph may be an important carbon carrier in regions of Earth's lower mantle. The depth at which carbonates will decompose is dependent on the age, temperature and density of subducting slabs. Decarbonation reactions may lower the melting temperature of surrounding rocks to produce silicate melts. In regions of the mantle where silicate melts may exist, it is important to understand the physical properties and dynamic behavior of the melts because they affect the chemical and thermal evolution of its interior. Composition, degree of polymerization, and iron's spin state affect such properties. The behavior of iron in silicate melts is poorly understood but, in some cases, may be approximated by iron-bearing glasses. We measured the hyperfine parameters of iron-bearing rhyolitic and basaltic glasses up to 120 GPa and 100 GPa, respectively, in a neon pressure medium using time-domain synchrotron Mössbauer spectroscopy. The spectra for rhyolitic and basaltic glasses are well explained by three high-spin Fe2+-like sites with distinct quadrupole splittings, reflecting the influence of evolving coordination environments with pressure. With the assumption that coordination environments in silicate glasses may serve as a good indicator for those in a melt, this study suggests that ferrous iron in chemically-complex silicate melts likely exists in a high-spin state throughout most of Earth's mantle.

A pilot study assessing the association between paraoxonase 1 gene polymorphism and prostate cancer.

PubMed

Uluocak, Nihat; Atılgan, Doğan; Parlaktaş, Bekir Süha; Erdemir, Fikret; Ateş, Ömer

2017-09-01

We aimed to show the relationship between paraoxonase 1 (PON1) gene polymorphism and the development of prostate cancer (PCa). We investigated the association of single nuclotide polymorphisms of PON1 enzyme with the development of PCa risk. A total of 147 male patients were divided into PCa, and control groups. The control group was also divided into two subgroups according to serum prostate specific antigen (PSA) levels as non PCa-high PSA (>4 ng/mL) and non PCa-low PSA (≤4 ng/mL) groups. The mean ages of the patients were 64.81 years, 63.27 years and 64.22 years in PCa group, non PCa-low PSA and non PCa -high PSA groups, respectively. The mean PSA levels were 10.9 ng/mL, 1.16 ng/mL and 6.63 ng/mL for PCa group, non PCa -low PSA and non PCa -high PSA groups, respectively. In terms of PON1 polymorphisms and allele frequencies, there were no statistically significant differences between PCa and control groups. There was not a statistically significant difference between PCa and non PCa-high PSA groups as for genotypic and allelic frequencies. As a result of this small sample sized hypothetical study of polymorphism, a relationship could not be detected between PCa development and PON1 gene polymorphism. According to the results of this preliminary study, it is thought that more comprehensive future studies are necessary to clarify the possible role of PON1 gene polymorphism in the etiology of PCa.

A pilot study assessing the association between paraoxonase 1 gene polymorphism and prostate cancer

PubMed Central

Uluocak, Nihat; Atılgan, Doğan; Parlaktaş, Bekir Süha; Erdemir, Fikret; Ateş, Ömer

2017-01-01

Objective We aimed to show the relationship between paraoxonase 1 (PON1) gene polymorphism and the development of prostate cancer (PCa). Material and methods We investigated the association of single nuclotide polymorphisms of PON1 enzyme with the development of PCa risk. A total of 147 male patients were divided into PCa, and control groups. The control group was also divided into two subgroups according to serum prostate specific antigen (PSA) levels as non PCa-high PSA (>4 ng/mL) and non PCa-low PSA (≤4 ng/mL) groups. Results The mean ages of the patients were 64.81 years, 63.27 years and 64.22 years in PCa group, non PCa-low PSA and non PCa –high PSA groups, respectively. The mean PSA levels were 10.9 ng/mL, 1.16 ng/mL and 6.63 ng/mL for PCa group, non PCa –low PSA and non PCa –high PSA groups, respectively. In terms of PON1 polymorphisms and allele frequencies, there were no statistically significant differences between PCa and control groups. There was not a statistically significant difference between PCa and non PCa-high PSA groups as for genotypic and allelic frequencies. As a result of this small sample sized hypothetical study of polymorphism, a relationship could not be detected between PCa development and PON1 gene polymorphism. Conclusion According to the results of this preliminary study, it is thought that more comprehensive future studies are necessary to clarify the possible role of PON1 gene polymorphism in the etiology of PCa. PMID:28861298

Correlated topographic and structural modification on Si surface during multi-shot femtosecond laser exposures: Si nanopolymorphs as potential local structural nanomarkers

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kudryashov, S. I.; Levchenko, A. O.; Nguyen, L. V.; Saraeva, I. N.; Rudenko, A. A.; Ageev, E. I.; Potorochin, D. V.; Veiko, V. P.; Borisov, E. V.; Pankin, D. V.; Kirilenko, D. A.; Brunkov, P. N.

2017-09-01

High-pressure Si-XII and Si-III nanocrystalline polymorphs, as well as amorphous Si phase, appear consequently during multi-shot femtosecond-laser exposure of crystalline Si wafer surface above its spallation threshold along with permanently developing quasi-regular surface texture (ripples, microcones), residual hydrostatic stresses and subsurface damage, which are characterized by scanning and transmission electron microscopy, as well as by Raman micro-spectroscopy. The consequent yields of these structural Si phases indicate not only their spatially different appearance, but also potentially enable to track nanoscale, transient laser-induced high-pressure, high-temperature physical processes - local variation of ablation mechanism and rate, pressurization/pressure release, melting/resolidification, amorphization, annealing - versus cumulative laser exposure and the related development of the surface topography.

Phase selective synthesis of quantum cutting nanophosphors and the observation of a spontaneous room temperature phase transition.

PubMed

Ghosh, Pushpal; Mudring, Anja-Verena

2016-04-21

Oxygen-free Eu(3+)-doped NaGdF4 nanocrystals with high quantum cutting efficiency are accessible at low temperatures (room temperature to 80 °C) using task-specific ionic liquids (ILs) as structure directing agents and only water as solvent. Selective tuning of the shape, morphology and, most importantly, the crystal phase of the host lattice is achieved by changing the alkyl side length, the H-bonding capabilities and the concentration of 1-alkyl-3-methylimidazolium bromide ILs, [C(n)mim]Br. When using [C2mim]Br, hexagonal NaGdF4 nanoparticles are obtained. In the case of methylimidazolium bromides with longer pendant alkyl chains such as butyl (C4), octyl (C8) or decyl (C10), extremely small nanoparticles of the cubic polymorph form, which then convert even at room temperature (RT) to the thermodynamically favored hexagonal modification. To the best of our knowledge, this kind of spontaneous phase transition is not yet reported. The hexagonal nanomaterial shows a substantial quantum cutting efficiency (154%) whilst in the cubic material, the effect is negligible (107%). The easy yet highly phase selective green synthesis of the materials promises large scale industrial application in environmentally benign energy efficient lighting.

Physical inactivity interacts with an endothelial lipase polymorphism to modulate high density lipoprotein cholesterol in the GOLDN study

USDA-ARS?s Scientific Manuscript database

BACKGROUND: Plasma high density lipoprotein (HDL) cholesterol (HDL-C) concentration is highly heritable but is also modifiable by environmental factors including physical activity. HDL-C response to exercise varies among individuals, and this variability may be associated with genetic polymorphism...

Association of COL1A1 polymorphism with high myopia: a Meta-analysis

PubMed Central

Jin, Guang-Ming; Zhao, Xiao-Jing; Chen, Ai-Ming; Chen, Yong-Xing; Li, Qin

2016-01-01

AIM To investigate the association between collagen type I alpha 1 (COL1A1) gene and high myopia. METHODS In this Meta-analysis, we examined 5 published case-control studies that involved 1942 high myopia cases and 2929 healthy controls to assess the association between the COL1A1 rs2075555 polymorphism and high myopia risk. We calculated the pooled odds ratios (ORs) of COL1A1 rs2075555 polymorphism in high myopia cases vs healthy controls to evaluate the strength of the association. RESULTS Overall, there was no significant difference both in the genotype and allele distributions of COL1A1 rs2075555 polymorphism between high myopia cases and healthy controls: CC vs AA OR=1.10, 95% confidence interval (CI)=0.76-1.58; AC vs AA OR=0.98, 95%CI 0.80-1.20; CC/AC vs AA/OR=1.01, 95%CI 0.84-1.22; CC vs AC/AA OR=1.06, 95%CI=0.93-1.20; C vs A OR=1.06, 95%CI 0.91-1.23). In addition, in the stratified analyses by ethnicity, no significant associations were found in any genetic model both in European and Asia cohorts. CONCLUSION Our results indicate that the COL1A1 rs2075555 polymorphism may not affect susceptibility to high myopia. PMID:27162737

[MSW incineration fly ash melting by DSC-DTA].

PubMed

Li, Rundong; Chi, Yong; Li, Shuiqing; Wang, Lei; Yan, Jianhua; Cen, Kefa

2002-07-01

Melting characteristics of two kinds of municipal solid waste incineration(MSWI) fly ash were studied in this paper by high temperature differential scanning calorimetry and differential temperature analysis. MSWI fly ash was considered as hazardous waste because it contains heavy metals and dioxins. The experiments were performed in either N2 or O2 atmosphere in temperature range of 20 degrees C-1450 degrees C at various heating rates. Two different MSW incineration fly ashes used in the experiments were collected from our country and France respectively. The process of fly ash melting exhibits two reactions occurring at temperature ranges of about 480 degrees C-670 degrees C and 1136 degrees C-1231 degrees C, respectively. The latent heat of polymorphic transformation and fusion were approximately 20 kJ/kg and 700 kJ/kg, while the total heat required for melting process was about 1800 kJ/kg. The paper also studied effect of CaO to melting. A heat flux thermodynamic model for fly ash melting was put forward and it agrees well with experimental data.

Quasi-dynamic pressure and temperature initiated β<-->δ solid phase transitions in HMX

NASA Astrophysics Data System (ADS)

Zaug, Joseph M.; Farber, Daniel L.; Craig, Ian M.; Blosch, Laura L.; Shuh, David K.; Hansen, Donald W.; Aracne-Ruddle, Chantel M.

2000-04-01

The phase transformation of β-HMX (>0.5% RDX) to δ phase has been studied for over twenty years and more recently with an high-contrast optical second harmonic generation technique. Shock studies of the plastic binder composites of HMX have indicated that the transition is perhaps irreversible, a result that concurs with the static pressure results published by F. Goetz et al. [1] in 1978. However, the stability field favors the β polymorph over δ as pressure is increased (up to 5.4 GPa) along any thermodynamically reasonable isotherm. In this experiment, strict control of pressure and temperature is maintained while x-ray and optical diagnostics are applied to monitor the conformational dynamics of HMX. Unlike the temperature induced β→δ transition, the pressure induced is heterogeneous in nature. The 1 bar 25 °C δ→β transition is not immediate, occuring over tens of hours. Transition points and kinetics are path dependent and consequently this paper describes our work in progress.

Phase transitions of CaCO3 at high P and T determined by in-situ Vibrational Spectroscopy in Diamond-Anvil-Cells

NASA Astrophysics Data System (ADS)

Koch-Müller, Monika; Jahn, Sandro; Birkholz, Natalie; Schade, Ulrich

2014-05-01

Carbonates are the most abundant carbon-bearing minerals on Earth. They can be transported into the upper and lower mantle via subduction processes. Knowledge of the stability of solid carbonates adapting different structures with increasing pressure and temperature is therefore of great importance to understand the structure and dynamics of the Earth. Even for the very simple system CaCO3 the phase relations of at high pressure and temperature are still not fully understood. It has been known for many years that calcite (cc) can adopt different structures with increasing pressure (e.g. Bridgman, 1939: cc-I to III; Tyburczy and Ahrens, 1986: cc-VI). But only recently Merlini et al. (2012) were able to solve the crystal structures of some of these high-pressure polymorphs namely cc-III, cc-IIIb and cc-VI. They report that cc-VI has a higher density then aragonite under the same conditions. To study the stability of the CaCO3-polymorphs, experiments were performed in conventional diamond anvil cells (DAC) at ambient temperatures as a function of pressure up to 30 GPa as well as in internally heated diamond anvil cells (DAC-HT) in the pressure range 9 to 20 GPa and temperatures up to 800 K. As probe for the structural changes we used conventional mid-infrared-, synchrotron far-infrared- and Raman-spectroscopy. Within the cc-III stability field (3 to 15 GPa at room temperature, e.g. Catalli and Williams, 2005) we observed in all types of experiments consistently two different spectral patterns: one at lower P < 5 GPa and another at P > 5 < 15 GPa independent on the starting material and the pressure- and time-path of the experiments. Whether these P-induced structural changes may be linked to the above mentioned different structures of cc-III is not yet clear. Also, in all types of experiments we confirmed the transition of cc-III to cc-VI at about 15 GPa at room temperature. Merlini et al. (2012) speculated that temperature may stabilize the structures of cc-III to lower pressure and surprisingly we found the same for the cc-III to cc-VI transition. The reaction has a negative slope of about -0.007 GPa/K. However, our density-functional theory calculations indicate that cc-VI is still metastable in respect to aragonite at least at zero K. We will prove if temperature and the incorporation of smaller cations than Ca have an influence on the stability relations. References: Bridgman P.W. (1939) Am J Sci, 237, 7 - 18. Catalli K. and Williams Q. (2005) Am Mineral, 90, 1679 - 1682. Merlini M. et al. (2012) EPSL, 333-334, 265 - 271. Tyburczy J. A. and Ahrens T. J. (1986) J Geophysical Research, 91, 4730 - 4744.

Asymmetric Dispersal Can Maintain Larval Polymorphism: A Model Motivated by Streblospio benedicti

PubMed Central

Zakas, Christina; Hall, David W.

2012-01-01

Polymorphism in traits affecting dispersal occurs in a diverse variety of taxa. Typically, the maintenance of a dispersal polymorphism is attributed to environmental heterogeneity where parental bet-hedging can be favored. There are, however, examples of dispersal polymorphisms that occur across similar environments. For example, the estuarine polychaete Streblospio benedicti has a highly heritable offspring dimorphism that affects larval dispersal potential. We use analytical models of dispersal to determine the conditions necessary for a stable dispersal polymorphism to exist. We show that in asexual haploids, sexual haploids, and in sexual diploids in the absence of overdominance, asymmetric dispersal is required in order to maintain a dispersal polymorphism when patches do not vary in intrinsic quality. Our study adds an additional factor, dispersal asymmetry, to the short list of mechanisms that can maintain polymorphism in nature. The region of the parameter space in which polymorphism is possible is limited, suggesting why dispersal polymorphisms within species are rare. PMID:22576818

PAI-1 expression and its regulation by promoter 4G/5G polymorphism in clear cell renal cell carcinoma.

PubMed

Choi, Jung-Woo; Lee, Ju-Han; Park, Hong Seok; Kim, Young-Sik

2011-10-01

To characterise patients with high plasminogen activator inhibitor-1 (PAI-1) expression as oral PAI-1 antagonists are currently in preclinical trials, and to determine whether the PAI-1 promoter 4G/5G polymorphism regulates PAI-1 expression in clear cell renal cell carcinoma (CCRCC). PAI-1 expression was examined by immunohistochemistry in 69 CCRCC specimens. In addition, the promoter 4G/5G polymorphism was investigated by both allele-specific PCR and direct DNA sequencing. PAI-1 was overexpressed in 25/69 (36.2%) patients with CCRCC. PAI-1 staining was intense in tumour cells with a high Fuhrman nuclear grade and in spindle-shaped tumour cells. PAI-1 expression was significantly associated with older age at diagnosis (p=0.027), high nuclear grade (p<0.001), advanced clinical stage (p=0.030) and distant metastasis (p=0.009). In survival analyses, PAI-1 expression was correlated with disease-free survival in Kaplan-Meier curves (p=0.015) but was not significant in the Cox hazards model (p=0.527). The frequencies of the promoter polymorphism were 24.6% (17/69) 4G/4G, 43.5% (30/69) 4G/5G and 31.9% (22/69) 5G/5G. The homozygous 4G/4G or 5G/5G group showed a tendency for a high nuclear grade (p=0.05) but the 4G/5G polymorphism was not related to other prognostic parameters. PAI-1 expression was poorly correlated with its promoter 4G/5G polymorphism (Spearman ρ=0.088). CCRCC with high PAI-1 expression is characterised by older age, high nuclear grade, advanced stage, distant metastasis and/or shortened disease-free survival. PAI-1 expression is not affected by the promoter 4G/5G polymorphism.

An effective 2-band eg model of sulfur hydride H3S for high-Tc superconductivity

NASA Astrophysics Data System (ADS)

Nishiguchi, Kazutaka; Teranishi, Shingo; Miyao, Satoaki; Matsushita, Goh; Kusakabe, Koichi

To understand high transition temperature (Tc) superconductivity in sulfur hydride H3S, we propose an effective 2-band model having the eg symmetry as the minimal model for H3S. Two eg orbitals centered on a sulfur S atom are chosen for the smallest representation of relevant bands with the van-Hove singularity around the Fermi levels except for the Γ-centered small hole pockets by the sulfur 3 p orbitals. By using the maximally localized Wannier functions, we derive the minimal effective model preserving the body-centered cubic (bcc) crystal symmetry of the H3S phase having the highest Tc ( 203 K under pressures) among the other polymorphs of H3S.

Review of calcium carbonate polymorph precipitation in spring systems

NASA Astrophysics Data System (ADS)

Jones, Brian

2017-05-01

Many spring deposits throughout the world are characterized by spectacular deposits of calcium carbonate that are formed of various combinations of aragonite and calcite, and in very rare cases vaterite. The factors that control the precipitation of the aragonite and calcite have been the subject of considerable debate that has been based on natural precipitates and information gained from numerous laboratory experiments. Synthesis of this information indicates that there is probably no single universal factor that controls calcite and aragonite precipitation in all springs. Instead, the reason for aragonite as opposed to calcite precipitation should be ascertained by considering the following ordered series of possibilities for each system. First, aragonite, commonly with calcite as a co-precipitate, will form from spring water that has a high CO2 content and rapid CO2 degassing, irrespective of the Mg:Ca ratio and scale of precipitation. Second, aragonite can be precipitated from waters that have low levels of CO2 degassing provided that the Mg:Ca ratio is high enough to inhibit calcite precipitation. Third, the presence of biofilms may lead to the simultaneous precipitation of aragonite and calcite (irrespective of CO2 degassing or Mg:Ca ratio) either within the different microdomains that develop in the biofilm or because of diurnal changes in various geochemical parameters associated with the biofilm. Although the precipitation of calcite and aragonite has commonly been linked directly to water temperature, there is no clear evidence for this proposition. It is possible, however, that temperature may be influencing another parameter that plays a more direct role in the precipitation of these CaCO3 polymorphs. Despite the advances that have been made, the factors that ultimately control calcite and aragonite are still open to debate because this long-standing problem has still not been fully resolved.

Significance of "stretched" mineral inclusions for reconstructing P- T exhumation history

NASA Astrophysics Data System (ADS)

Ashley, Kyle T.; Darling, Robert S.; Bodnar, Robert J.; Law, Richard D.

2015-06-01

Analysis of mineral inclusions in chemically and physically resistant hosts has proven to be valuable for reconstructing the P- T exhumation history of high-grade metamorphic rocks. The occurrence of cristobalite-bearing inclusions in garnets from Gore Mountain, New York, is unexpected because the peak metamorphic conditions reached are well removed (>600 °C too cold) from the stability field of this low-density silica polymorph that typically forms in high temperature volcanic environments. A previous study of samples from this area interpreted polymineralic inclusions consisting of cristobalite, albite and ilmenite as representing crystallized droplets of melt generated during a garnet-in reaction, followed by water loss from the inclusion to explain the reduction in inclusion pressure that drove the transformation of quartz to cristobalite. However, the recent discovery of monomineralic inclusions of cristobalite from the nearby Hooper Mine cannot be explained by this process. For these inclusions, we propose that the volume response to pressure and temperature changes during exhumation to Earth's surface resulted in large tensile stresses within the silica phase that would be sufficient to cause transformation to the low-density (low-pressure) form. Elastic modeling of other common inclusion-host systems suggests that this quartz-to-cristobalite example may not be a unique case. The aluminosilicate polymorph kyanite also has the capacity to retain tensile stresses if exhumed to Earth's surface after being trapped as an inclusion in plagioclase at P- T conditions within the kyanite stability field, with the stresses developed during exhumation sufficient to produce a transformation to andalusite. These results highlight the elastic environment that may arise during exhumation and provide a potential explanation of observed inclusions whose stability fields are well removed from P- T paths followed during exhumation.

Three reversible polymorphic copper(I) complexes triggered by ligand conformation: insights into polymorphic crystal habit and luminescent properties.

PubMed

Chai, Wenxiang; Hong, Mingwei; Song, Li; Jia, Guohua; Shi, Hongsheng; Guo, Jiayu; Shu, Kangying; Guo, Bing; Zhang, Yicheng; You, Wenwu; Chen, Xueyuan

2015-05-04

Three luminescent polymorphs based on a new copper(I) complex Cu(2-QBO)(PPh3)PF6 (1, PPh3 = triphenylphosphine, 2-QBO = 2-(2'-quinolyl)benzoxazole) have been synthesized and characterized by FT-IR, UV-vis, elemental analyses, and single-crystal X-ray diffraction analyses. Each polymorph can reversibly convert from one to another through appropriate procedures. Interestingly, such interconversion can be distinguished by their intrinsic crystal morphologies and colors (namely α, dark yellow plate, β, orange block, γ, light yellow needle) as well as photoluminescent (PL) properties. X-ray crystal structure analyses of these three polymorphs show three different supramolecular structures from 1D to 3D, which are expected to be responsible for the formation of three different crystal morphologies such as needle, plate, and block. Combination of the experimental data with DFT calculations on these three polymorphs reveals that the polymorphic interconversion is triggered by the conformation isomerization of the 2-QBO ligand and can be successfully controlled by the polarity of the process solvents (affecting the molecular dipole moment) and thermodynamics (affecting the molecular total energy). It is also found that the different crystal colors of polymorphs and their PL properties are derived from different θ values (dihedral angle between benzoxazolyl and quinolyl group of the 2-QBO ligand) and P-Cu-P angles based on TD-DFT calculations. Moreover, an interesting phase interconversion between γ and β has also been found under different temperature, and this result is consistent with the DFT calculations in which the total energy of β is larger than that of γ. This polymorphism provides a good model to study the relationship between the structure and the physical properties in luminescent copper(I) complexes as well as some profound insights into their PL properties.

Influence of polymorphism on the surface energetics of salmeterol xinafoate crystallized from supercritical fluids.

PubMed

Tong, Henry H Y; Shekunov, Boris Yu; York, Peter; Chow, Albert H L

2002-05-01

To characterize the surface thermodynamic properties of two polymorphic forms (I and II) of salmeterol xinafoate (SX) prepared from supercritical fluids and a commercial micronized SX (form 1) sample (MSX). Inverse gas chromatographic analysis was conducted on the SX samples at 30, 40, 50, and 60 degrees C using the following probes at infinite dilution: nonpolar probes (NPs; alkane C5-C9 series); and polar probes (PPs; i.e., dichloromethane, chloroform, acetone, ethyl acetate, diethyl ether, and tetrahydrofuran). Surface thermodynamic parameters of adsorption and Hansen solubility parameters were calculated from the retention times of the probes. The free energies of adsorption (- deltaG(A)) of the three samples obtained at various temperatures follow this order: SX-II > MSX approximately/= SX-I for the NPs; and SX-II > MSX > SX-I for the PPs. For both NPs and PPs, SX-II exhibits a less negative enthalpy of adsorption (deltaH(A)) and a much less negative entropy of adsorption (ASA) than MSX and SX-I, suggesting that the high -AGA of SX-II is contributed by a considerably reduced entropy loss. The dispersive component of surface free energy (gammas(D)) is the highest for MSX but the lowest for SX-II at all temperatures studied, whereas the specific component of surface free energy of adsorption (-deltaG(A)SP) is higher for SX-II than for SX-I. That SX-II displays the highest -deltaG(A) for the NP but the lowest gammasD of all the SX samples may be explained by the additional -AGA change associated with an increased mobility of the probe molecules on the less stable and more disordered SX-II surface. The acid and base parameters, K(A) and K(D) that were derived from deltaH(A)SP reveal significant differences in the relative acid and base properties among the samples. The calculated Hansen solubility parameters (deltaD, deltap, and deltaH) indicate that the surface of SX-II is the most polar and most energetic of all the three samples in terms of specific interactions (mostly hydrogen bonding). The metastable SX-II polymorph possesses a higher surface free energy, higher surface entropy, and a more polar surface than the stable SX-I polymorph.

Selection and use of microsatellite markers for individual identification and meat traceability of six swine breeds in the Chinese market.

PubMed

Zhao, Jie; Li, Tingting; Zhu, Chao; Jiang, Xiaoling; Zhao, Yan; Xu, Zhenzhen; Yang, Shuming; Chen, Ailiang

2018-06-01

Meat traceability based on molecular markers is exerting a great influence on food safety and will enhance its key role in the future. This study aimed to investigate and verify the polymorphism of 23 microsatellite markers and select the most suitable markers for individual identification and meat traceability of six swine breeds in the Chinese market. The mean polymorphism information content value of these 23 loci was 0.7851, and each locus exhibited high polymorphism in the pooled population. There were 10 loci showing good polymorphism in each breed, namely, Sw632, S0155, Sw2406, Sw830, Sw2525, Sw72, Sw2448, Sw911, Sw122 and CGA. When six highly polymorphic loci were combined, the match probability value for two random individual genotypes among the pig breeds (Beijing Black, Sanyuan and Taihu) was lower than 1.151 E-06. An increasing number of loci indicated a gradually decreasing match probability value and therefore enhanced traceability accuracy. The validation results of tracing 18 blood and corresponding meat samples based on five highly polymorphic loci (Sw2525, S0005, Sw0107, Sw911 and Sw857) were successful, with 100% conformation probability, which provided a foundation for establishing a traceability system for pork in the Chinese market.

Reduction of the allotropic transition temperature in nanocrystalline zirconium: Predicted by modified equation of state (MEOS) method and molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Salati, Amin; Mokhtari, Esmail; Panjepour, Masoud; Aryanpour, Gholamreza

2013-04-01

The temperature at which polymorphic phase transformation occurs in nanocrystalline (NC) materials is different from that of coarse-grained specimens. This anomaly has been related to the role of grain boundary component in these materials and can be predicted by a dilated crystal model. In this study, based on this model, a modified equation of state (MEOS) method (instead of equation of state, EOS, method) is used to calculate the total Gibbs free energy of each phase (β-Zr or α-Zr) in NC Zr. Thereupon, the change in the total Gibbs free energy for β-Zr to α-Zr phase transformation (ΔGβ→α) via the grain size is calculated by this method. Similar to polymorphic transformation in other NC materials (Fe, Nb, Co, TiO2, Al2O3 and ZnS), it is found that the estimated transformation temperature in NC Zr (β→α) is reduced with decreasing grain size. Finally, a molecular dynamics (MD) simulation is employed to confirm the theoretical results.

The Nominal/Generic Specific Heat per Average Atom Concept for CHNO Energetic Materials

DTIC Science & Technology

2006-07-01

Heat Per Average Atom for TATB. RDX . TNT. HMX . and HNS... HMX can exist in different solid polymorphic forms. At a certain temperature, TT, one form may change to another form if the heat energy of...densities ( p. ) up to, and including, crystals at TMD for TNT, RDX , HMX , and TATB. The presently proposed N/G CP magnitude, in certain temperature

How and how much does RAD-seq bias genetic diversity estimates?

PubMed

Cariou, Marie; Duret, Laurent; Charlat, Sylvain

2016-11-08

RAD-seq is a powerful tool, increasingly used in population genomics. However, earlier studies have raised red flags regarding possible biases associated with this technique. In particular, polymorphism on restriction sites results in preferential sampling of closely related haplotypes, so that RAD data tends to underestimate genetic diversity. Here we (1) clarify the theoretical basis of this bias, highlighting the potential confounding effects of population structure and selection, (2) confront predictions to real data from in silico digestion of full genomes and (3) provide a proof of concept toward an ABC-based correction of the RAD-seq bias. Under a neutral and panmictic model, we confirm the previously established relationship between the true polymorphism and its RAD-based estimation, showing a more pronounced bias when polymorphism is high. Using more elaborate models, we show that selection, resulting in heterogeneous levels of polymorphism along the genome, exacerbates the bias and leads to a more pronounced underestimation. On the contrary, spatial genetic structure tends to reduce the bias. We confront the neutral and panmictic model to "ideal" empirical data (in silico RAD-sequencing) using full genomes from natural populations of the fruit fly Drosophila melanogaster and the fungus Shizophyllum commune, harbouring respectively moderate and high genetic diversity. In D. melanogaster, predictions fit the model, but the small difference between the true and RAD polymorphism makes this comparison insensitive to deviations from the model. In the highly polymorphic fungus, the model captures a large part of the bias but makes inaccurate predictions. Accordingly, ABC corrections based on this model improve the estimations, albeit with some imprecisions. The RAD-seq underestimation of genetic diversity associated with polymorphism in restriction sites becomes more pronounced when polymorphism is high. In practice, this means that in many systems where polymorphism does not exceed 2 %, the bias is of minor importance in the face of other sources of uncertainty, such as heterogeneous bases composition or technical artefacts. The neutral panmictic model provides a practical mean to correct the bias through ABC, albeit with some imprecisions. More elaborate ABC methods might integrate additional parameters, such as population structure and selection, but their opposite effects could hinder accurate corrections.

Development and application of a 6.5 million feature Affymetrix Genechip® for massively parallel discovery of single position polymorphisms in lettuce (Lactuca spp.)

PubMed Central

2012-01-01

Background High-resolution genetic maps are needed in many crops to help characterize the genetic diversity that determines agriculturally important traits. Hybridization to microarrays to detect single feature polymorphisms is a powerful technique for marker discovery and genotyping because of its highly parallel nature. However, microarrays designed for gene expression analysis rarely provide sufficient gene coverage for optimal detection of nucleotide polymorphisms, which limits utility in species with low rates of polymorphism such as lettuce (Lactuca sativa). Results We developed a 6.5 million feature Affymetrix GeneChip® for efficient polymorphism discovery and genotyping, as well as for analysis of gene expression in lettuce. Probes on the microarray were designed from 26,809 unigenes from cultivated lettuce and an additional 8,819 unigenes from four related species (L. serriola, L. saligna, L. virosa and L. perennis). Where possible, probes were tiled with a 2 bp stagger, alternating on each DNA strand; providing an average of 187 probes covering approximately 600 bp for each of over 35,000 unigenes; resulting in up to 13 fold redundancy in coverage per nucleotide. We developed protocols for hybridization of genomic DNA to the GeneChip® and refined custom algorithms that utilized coverage from multiple, high quality probes to detect single position polymorphisms in 2 bp sliding windows across each unigene. This allowed us to detect greater than 18,000 polymorphisms between the parental lines of our core mapping population, as well as numerous polymorphisms between cultivated lettuce and wild species in the lettuce genepool. Using marker data from our diversity panel comprised of 52 accessions from the five species listed above, we were able to separate accessions by species using both phylogenetic and principal component analyses. Additionally, we estimated the diversity between different types of cultivated lettuce and distinguished morphological types. Conclusion By hybridizing genomic DNA to a custom oligonucleotide array designed for maximum gene coverage, we were able to identify polymorphisms using two approaches for pair-wise comparisons, as well as a highly parallel method that compared all 52 genotypes simultaneously. PMID:22583801

Development and application of a 6.5 million feature Affymetrix Genechip® for massively parallel discovery of single position polymorphisms in lettuce (Lactuca spp.).

PubMed

Stoffel, Kevin; van Leeuwen, Hans; Kozik, Alexander; Caldwell, David; Ashrafi, Hamid; Cui, Xinping; Tan, Xiaoping; Hill, Theresa; Reyes-Chin-Wo, Sebastian; Truco, Maria-Jose; Michelmore, Richard W; Van Deynze, Allen

2012-05-14

High-resolution genetic maps are needed in many crops to help characterize the genetic diversity that determines agriculturally important traits. Hybridization to microarrays to detect single feature polymorphisms is a powerful technique for marker discovery and genotyping because of its highly parallel nature. However, microarrays designed for gene expression analysis rarely provide sufficient gene coverage for optimal detection of nucleotide polymorphisms, which limits utility in species with low rates of polymorphism such as lettuce (Lactuca sativa). We developed a 6.5 million feature Affymetrix GeneChip® for efficient polymorphism discovery and genotyping, as well as for analysis of gene expression in lettuce. Probes on the microarray were designed from 26,809 unigenes from cultivated lettuce and an additional 8,819 unigenes from four related species (L. serriola, L. saligna, L. virosa and L. perennis). Where possible, probes were tiled with a 2 bp stagger, alternating on each DNA strand; providing an average of 187 probes covering approximately 600 bp for each of over 35,000 unigenes; resulting in up to 13 fold redundancy in coverage per nucleotide. We developed protocols for hybridization of genomic DNA to the GeneChip® and refined custom algorithms that utilized coverage from multiple, high quality probes to detect single position polymorphisms in 2 bp sliding windows across each unigene. This allowed us to detect greater than 18,000 polymorphisms between the parental lines of our core mapping population, as well as numerous polymorphisms between cultivated lettuce and wild species in the lettuce genepool. Using marker data from our diversity panel comprised of 52 accessions from the five species listed above, we were able to separate accessions by species using both phylogenetic and principal component analyses. Additionally, we estimated the diversity between different types of cultivated lettuce and distinguished morphological types. By hybridizing genomic DNA to a custom oligonucleotide array designed for maximum gene coverage, we were able to identify polymorphisms using two approaches for pair-wise comparisons, as well as a highly parallel method that compared all 52 genotypes simultaneously.

Crystallization of Calcium Carbonate in a Large Scale Field Study

NASA Astrophysics Data System (ADS)

Ueckert, Martina; Wismeth, Carina; Baumann, Thomas

2017-04-01

The long term efficiency of geothermal facilities and aquifer thermal energy storage in the carbonaceous Malm aquifer in the Bavarian Molasse Basin is seriously affected by precipitations of carbonates. This is mainly caused by pressure and temperature changes leading to oversaturation during production. Crystallization starts with polymorphic nuclei of calcium carbonate and is often described as diffusion-reaction controlled. Here, calcite crystallization is favoured by high concentration gradients while aragonite crystallization is occurring at high reaction rates. The factors affecting the crystallization processes have been described for simplified, well controlled laboratory experiments, the knowledge about the behaviour in more complex natural systems is still limited. The crystallization process of the polymorphic forms of calcium carbonate were investigated during a heat storage test at our test site in the eastern part of the Bavarian Molasse Basin. Complementary laboratory experiments in an autoclave were run. Both, field and laboratory experiments were conducted with carbonaceous tap water. Within the laboratory experiments additionally ultra pure water was used. To avoid precipitations of the tap water, a calculated amount of {CO_2} was added prior to heating the water from 45 - 110°C (laboratory) resp. 65 - 110°C (field). A total water volume of 0.5 L (laboratory) resp. 1 L (field) was immediately sampled and filtrated through 10 - 0.1

Negative-pressure polymorphs made by heterostructural alloying

PubMed Central

Perkins, John D.

2018-01-01

The ability of a material to adopt multiple structures, known as polymorphism, is a fascinating natural phenomenon. Various polymorphs with unusual properties are routinely synthesized by compression under positive pressure. However, changing a material’s structure by applying tension under negative pressure is much more difficult. We show how negative-pressure polymorphs can be synthesized by mixing materials with different crystal structures—a general approach that should be applicable to many materials. Theoretical calculations suggest that it costs less energy to mix low-density structures than high-density structures, due to less competition for space between the atoms. Proof-of-concept experiments confirm that mixing two different high-density forms of MnSe and MnTe stabilizes a Mn(Se,Te) alloy with a low-density wurtzite structure. This Mn(Se,Te) negative-pressure polymorph has 2× to 4× lower electron effective mass compared to MnSe and MnTe parent compounds and has a piezoelectric response that none of the parent compounds have. This example shows how heterostructural alloying can lead to negative-pressure polymorphs with useful properties—materials that are otherwise nearly impossible to make. PMID:29725620

Genomic polymorphism, recombination, and linkage disequilibrium in human major histocompatibility complex-encoded antigen-processing genes.

PubMed Central

van Endert, P M; Lopez, M T; Patel, S D; Monaco, J J; McDevitt, H O

1992-01-01

Recently, two subunits of a large cytosolic protease and two putative peptide transporter proteins were found to be encoded by genes within the class II region of the major histocompatibility complex (MHC). These genes have been suggested to be involved in the processing of antigenic proteins for presentation by MHC class I molecules. Because of the high degree of polymorphism in MHC genes, and previous evidence for both functional and polypeptide sequence polymorphism in the proteins encoded by the antigen-processing genes, we tested DNA from 27 consanguineous human cell lines for genomic polymorphism by restriction fragment length polymorphism (RFLP) analysis. These studies demonstrate a strong linkage disequilibrium between TAP1 and LMP2 RFLPs. Moreover, RFLPs, as well as a polymorphic stop codon in the telomeric TAP2 gene, appear to be in linkage disequilibrium with HLA-DR alleles and RFLPs in the HLA-DO gene. A high rate of recombination, however, seems to occur in the center of the complex, between the TAP1 and TAP2 genes. Images PMID:1360671

Negative-pressure polymorphs made by heterostructural alloying.

PubMed

Siol, Sebastian; Holder, Aaron; Steffes, James; Schelhas, Laura T; Stone, Kevin H; Garten, Lauren; Perkins, John D; Parilla, Philip A; Toney, Michael F; Huey, Bryan D; Tumas, William; Lany, Stephan; Zakutayev, Andriy

2018-04-01

The ability of a material to adopt multiple structures, known as polymorphism, is a fascinating natural phenomenon. Various polymorphs with unusual properties are routinely synthesized by compression under positive pressure. However, changing a material's structure by applying tension under negative pressure is much more difficult. We show how negative-pressure polymorphs can be synthesized by mixing materials with different crystal structures-a general approach that should be applicable to many materials. Theoretical calculations suggest that it costs less energy to mix low-density structures than high-density structures, due to less competition for space between the atoms. Proof-of-concept experiments confirm that mixing two different high-density forms of MnSe and MnTe stabilizes a Mn(Se,Te) alloy with a low-density wurtzite structure. This Mn(Se,Te) negative-pressure polymorph has 2× to 4× lower electron effective mass compared to MnSe and MnTe parent compounds and has a piezoelectric response that none of the parent compounds have. This example shows how heterostructural alloying can lead to negative-pressure polymorphs with useful properties-materials that are otherwise nearly impossible to make.

Cytotoxic T-lymphocyte-associated protein 4 gene polymorphism is related to rheumatoid arthritis in Egyptian population.

PubMed

Fattah, Shaimaa A; Ghattas, Maivel H; Saleh, Samy M; Abo-Elmatty, Dina M

2017-02-01

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a CD28-family receptor expressed on T-cells which suppresses T cell proliferation. CTLA-4 -318C/T polymorphism is involved in regulation of CTLA-4 expression. The study aimed to investigate the genetic association of CTLA-4 -318C/T polymorphism with rheumatoid arthritis (RA) and the activity and severity of the disease in the Egyptian population. A single nucleotide polymorphism (rs5742909) in CTLA-4 was genotyped in 100 RA patients and 100 healthy controls using polymerase chain reaction-restriction fragment length polymorphism. Diagnostic tests were measured for RA patients. The frequency of T allele in RA patients was significantly higher than in the control subjects (p = 0.002). CT and TT genotypes had high C-reactive protein, erythrocyte sedimentation rate and disease activity score 28 while CC genotype had a high rheumatoid factor. A minor allele of CTLA-4 rs5742909 polymorphism was associated with RA and the activity but not the severity of the disease.

Genetic differences in human circadian clock genes among worldwide populations.

PubMed

Ciarleglio, Christopher M; Ryckman, Kelli K; Servick, Stein V; Hida, Akiko; Robbins, Sam; Wells, Nancy; Hicks, Jennifer; Larson, Sydney A; Wiedermann, Joshua P; Carver, Krista; Hamilton, Nalo; Kidd, Kenneth K; Kidd, Judith R; Smith, Jeffrey R; Friedlaender, Jonathan; McMahon, Douglas G; Williams, Scott M; Summar, Marshall L; Johnson, Carl Hirschie

2008-08-01

The daily biological clock regulates the timing of sleep and physiological processes that are of fundamental importance to human health, performance, and well-being. Environmental parameters of relevance to biological clocks include (1) daily fluctuations in light intensity and temperature, and (2) seasonal changes in photoperiod (day length) and temperature; these parameters vary dramatically as a function of latitude and locale. In wide-ranging species other than humans, natural selection has genetically optimized adaptiveness along latitudinal clines. Is there evidence for selection of clock gene alleles along latitudinal/photoperiod clines in humans? A number of polymorphisms in the human clock genes Per2, Per3, Clock, and AANAT have been reported as alleles that could be subject to selection. In addition, this investigation discovered several novel polymorphisms in the human Arntl and Arntl2 genes that may have functional impact upon the expression of these clock transcriptional factors. The frequency distribution of these clock gene polymorphisms is reported for diverse populations of African Americans, European Americans, Ghanaians, Han Chinese, and Papua New Guineans (including 5 subpopulations within Papua New Guinea). There are significant differences in the frequency distribution of clock gene alleles among these populations. Population genetic analyses indicate that these differences are likely to arise from genetic drift rather than from natural selection.

Unraveling the Decomposition Process of Lead(II) Acetate: Anhydrous Polymorphs, Hydrates, and Byproducts and Room Temperature Phosphorescence.

PubMed

Martínez-Casado, Francisco J; Ramos-Riesco, Miguel; Rodríguez-Cheda, José A; Cucinotta, Fabio; Matesanz, Emilio; Miletto, Ivana; Gianotti, Enrica; Marchese, Leonardo; Matěj, Zdeněk

2016-09-06

Lead(II) acetate [Pb(Ac)2, where Ac = acetate group (CH3-COO(-))2] is a very common salt with many and varied uses throughout history. However, only lead(II) acetate trihydrate [Pb(Ac)2·3H2O] has been characterized to date. In this paper, two enantiotropic polymorphs of the anhydrous salt, a novel hydrate [lead(II) acetate hemihydrate: Pb(Ac)2·(1)/2H2O], and two decomposition products [corresponding to two different basic lead(II) acetates: Pb4O(Ac)6 and Pb2O(Ac)2] are reported, with their structures being solved for the first time. The compounds present a variety of molecular arrangements, being 2D or 1D coordination polymers. A thorough thermal analysis, by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), was also carried out to study the behavior and thermal data of the salt and its decomposition process, in inert and oxygenated atmospheres, identifying the phases and byproducts that appear. The complex thermal behavior of lead(II) acetate is now solved, finding the existence of another hydrate, two anhydrous enantiotropic polymorphs, and some byproducts. Moreover, some of them are phosphorescent at room temperature. The compounds were studied by TGA, DSC, X-ray diffraction, and UV-vis spectroscopy.

Polymorphisms in the ghrelin gene are associated with serum high-density lipoprotein cholesterol level and not with type 2 diabetes mellitus in Koreans.

PubMed

Choi, Hyung Jin; Cho, Young Min; Moon, Min Kyong; Choi, Hye Hun; Shin, Hyoung Doo; Jang, Hak Chul; Kim, Seong Yeon; Lee, Hong Kyu; Park, Kyong Soo

2006-11-01

Ghrelin is known to play a role in glucose metabolism and in beta-cell function. There are controversies regarding the role of ghrelin polymorphisms in diabetes and diabetes-related phenotypes. The objective of this study was to examine polymorphisms of the ghrelin gene in a Korean cohort and investigate associations between them and susceptibility to type 2 diabetes and its related phenotypes. The ghrelin gene was sequenced to identify polymorphisms in 24 DNA samples. Common variants were then genotyped in 760 type 2 diabetic patients and 641 nondiabetic subjects. Genetic associations with diabetes-related phenotypes were also analyzed. Nine polymorphisms were identified, and four common polymorphisms [g.-1500C>G, g.-1062G > C, g.-994C > T, g.+408C > A (Leu72Met)] were genotyped in a larger study. The genotype distributions of these four common polymorphisms in type 2 diabetes patients were similar to those of normal nondiabetic controls. However, these four common polymorphisms were variably associated with several diabetes-related phenotypes, such as high-density lipoprotein (HDL) cholesterol, fasting plasma glucose, and homeostasis model assessment of insulin resistance. In particular, subjects harboring g.-1062C were associated with a lower serum HDL cholesterol level after adjusting for other variables (P = 0.0004 or 0.01 after Bonferroni correction for 24 tests). The aforementioned four common polymorphisms in the ghrelin gene were not found to be significantly associated with susceptibility to type 2 diabetes mellitus in the Korean population. However, the common polymorphism g.-1062G > C in the promoter region of the ghrelin gene was found to be significantly associated with serum HDL cholesterol levels.

Studies of isothermal crystallisation kinetics of sunflower hard stearin-based confectionery fats.

PubMed

Bootello, Miguel A; Hartel, Richard W; Levin, Madeline; Martínez-Blanes, Jose M; Real, Concepción; Garcés, Rafael; Martínez-Force, Enrique; Salas, Joaquín J

2013-08-15

The crystallisation and polymorphic properties of three sunflower hard stearins (SHSs) and cocoa butter equivalents (CBEs) formulated by blending SHSs and palm mid fraction (PMF) were studied and compared with those from cocoa butter (CB), to explore their possibilities as confectionery fats. The isothermal crystallisation kinetics of these fats were examined by pNMR and DSC at three different temperatures. All samples studied displayed a two-step crystallisation profile that could be fitted to an exponential-Gompertz equation. Stop-and-return DSC studies showed that SHSs and CBEs exhibited different crystallisation mechanisms according to their triacylglycerol composition, with a quick formation of metastable crystals, followed by a polymorphic transition to the more stable β or β' forms. X-ray diffraction (XRD) was used to investigate the polymorphic forms of tempered SHSs and CBEs in the long term. In all cases the resulting fats displayed short spacing patterns associated with β polymorphism. These formulations based on SHSs and PMF met all the requirements to be considered as CBEs; therefore they could be used as an alternative to traditional confectionery fats. Copyright © 2013 Elsevier Ltd. All rights reserved.

Supercritical carbon dioxide treatment as a method for polymorph preparation of deoxycholic acid.

PubMed

Tozuka, Yuichi; Kawada, Dai; Oguchi, Toshio; Yamamoto, Keiji

2003-09-16

A new polymorph of deoxycholic acid (DCA) was formed by using a supercritical carbon dioxide treatment. Deoxycholic acid crystals were stored in a pressure vessel purged with carbon dioxide at 12MPa, 60 degrees C for definite intervals. After storage for 1h in supercritical carbon dioxide (SC-CO2), new X-ray diffraction (XRD) peaks, not found in the bulk DCA crystal, were observed at 2theta = 7.4 degrees, 9.7 degrees and 14.0 degrees. The intensities of the new diffraction peaks increased with an increase in storage time, whereas the intensities of the diffraction peaks due to bulk DCA crystal decreased. On the DSC curves, the crystals obtained showed an exothermic peak at around 155 degrees C followed by the melting peak of bulk DCA crystal at 175 degrees C. By the temperature-controlled powder XRD measurement, the crystals obtained were found to be a metastable form of DCA. The polymorphs of DCA have not been reported; therefore, the SC-CO2 treatment would be a peculiar method to obtain a DCA polymorph.

A first-principles study on new high-pressure metastable polymorphs of MoO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, Nils; Dronskowski, Richard; Jülich-Aachen Research Alliance

The pressure-dependence of the stabilities of several MoO{sub 2} phases has been investigated by density-functional theory (GGA/PBE/PAW). Out of a set of 15 MX{sub 2} structures, the [SnO{sub 2}(II)], [α-PbO{sub 2}], and a modified rutile structure type were identified as possible metastable MoO{sub 2} polymorphs based on the analysis of thermodynamic properties and dynamic stability. High-pressure calculations suggest an orthorhombic TiO{sub 2} structure, dubbed [ortho-TiO{sub 2}], as a high-pressure polymorph at around 25 GPa. Furthermore, we find that the previously reported rutile-type MoO{sub 2} may be understood as a modified rutile type similar to the [VO{sub 2}] structure. - Graphicalmore » abstract: First-principles electronic structure and thermochemical calculations reveal four structure candidates as possible metastable polymorphs of MoO{sub 2}. Most promising is a distorted rutile-type similar to the known [VO{sub 2}] structure. An orthorhombic polymorph is proposed as a high-pressure polymorph. Display Omitted - Highlights: • Three possible metastable structure candidates for MoO{sub 2}. • Undistorted rutile type is improbable, a new distorted rutile-type MoO{sub 2} was suggested. • Orthorhombic phase of MoO{sub 2} (ortho-TiO{sub 2} type) should form at 25 GPa. • ab initio thermochemical data provided for MoO{sub 2}.« less

High-pressure polymorphism of acetylsalicylic acid (aspirin): Raman spectroscopy

NASA Astrophysics Data System (ADS)

Crowell, Ethan L.; Dreger, Zbigniew A.; Gupta, Yogendra M.

2015-02-01

Micro-Raman spectroscopy was used to elucidate the high-pressure polymorphic behavior of acetylsalicylic acid (ASA), an important pharmaceutical compound known as aspirin. Using a diamond anvil cell (DAC), single crystals of the two polymorphic phases of aspirin existing at ambient conditions (ASA-I and ASA-II) were compressed to 10 GPa. We found that ASA-I does not transform to ASA-II, but instead transforms to a new phase (ASA-III) above ∼2 GPa. It is demonstrated that this transformation primarily introduces structural changes in the bonding and arrangement of the acetyl groups and is reversible upon the release of pressure. In contrast, a less dense ASA-II shows no transition in the pressure range studied, though it appears to exhibit a disordered structure above 7 GPa. Our results suggest that ASA-III is the most stable polymorph of aspirin at high pressures.

Ecological separation in a polymorphic terrestrial salamander.

PubMed

Anthony, Carl D; Venesky, Matthew D; Hickerson, Cari-Ann M

2008-07-01

1. When studying speciation, researchers commonly examine reproductive isolation in recently diverged populations. Polymorphic species provide an opportunity to examine the role of reproductive isolation in populations that may be in the process of divergence. 2. We examined a polymorphic population of Plethodon cinereus (red-backed salamanders) for evidence of sympatric ecological separation by colour morphology. Recent studies have correlated temperature and climate with colour morphology in this species, but no studies have looked at differences in diet or mate choice between colour morphs. We used artificial cover objects to assess salamander diet, mating preference and surface activity over a 2-year period at a field site in north-eastern Ohio. 3. We detected differences in diet between two colour morphs, striped and unstriped. The diets of striped individuals were significantly more diverse and were made up of more profitable prey than the diets of unstriped salamanders. 4. Opposite sex pairs were made up of individuals of the same colour morph and striped males were found more often with larger females than were unstriped males. 5. We corroborate findings of earlier studies suggesting that the unstriped form is adapted to warmer conditions. Unstriped individuals were the first to withdraw from the forest floor as temperatures fell in the late fall. We found no evidence that the colour morphs responded differently to abiotic factors such as soil moisture and relative humidity, and responses to surface temperatures were also equivocal. 6. We conclude that the two colour morphs exhibit some degree of ecological separation and tend to mate assortatively, but are unlikely to be undergoing divergence given the observed frequency of intermorph pairings.

Thermal plasticity in life-history traits in the polymorphic blue-tailed damselfly, Ischnura elegans: no differences between female morphs.

PubMed

Bouton, Niels; Iserbyt, Arne; Van Gossum, Hans

2011-01-01

Female polymorphism is observed in various animal species, but is particularly common in damselflies. The maintenance of this polymorphism has traditionally been explained from frequency and density dependent sexual conflict, however, the role of abiotic factors has recently attracted more interest. Here, the role of ambient temperature in shaping life-history was investigated for the three female morphs of Ischnura elegans (Vander Linden) (Zygoptera: Coenagrionidae). Eggs were obtained from the three mature female morphs for two populations in the Netherlands. Using a split-brood design, eggs of both populations were divided between a cold and a warm treatment group in the laboratory, and egg survival and hatching time were measured. Significant thermal plasticity was found in both hatching time and egg survival between both temperature treatments. However, individuals born to mothers belonging to different colour morphs did not differ in their response to temperature treatment. Independent of colour morph, clear differences in both life-history traits between the populations were found, suggesting local adaptation. Specifically, individuals from one population hatched faster but had lower egg survival in both thermal regimes. The selection force establishing fast hatching could be (facultative) bivoltinism in one of the populations compared to univoltinism in the other. This would be in line with the more southern (and more coastal) location of the presumed bivoltine population and the inverse relation between voltinism and latitude known from earlier studies. However, other natural selection forces, e.g. deterioration of the aquatic habitat, may also drive fast hatching.

New data from basal Australian songbird lineages show that complex structure of MHC class II β genes has early evolutionary origins within passerines.

PubMed

Balasubramaniam, Shandiya; Bray, Rebecca D; Mulder, Raoul A; Sunnucks, Paul; Pavlova, Alexandra; Melville, Jane

2016-05-21

The major histocompatibility complex (MHC) plays a crucial role in the adaptive immune system and has been extensively studied across vertebrate taxa. Although the function of MHC genes appears to be conserved across taxa, there is great variation in the number and organisation of these genes. Among avian species, for instance, there are notable differences in MHC structure between passerine and non-passerine lineages: passerines typically have a high number of highly polymorphic MHC paralogs whereas non-passerines have fewer loci and lower levels of polymorphism. Although the occurrence of highly polymorphic MHC paralogs in passerines is well documented, their evolutionary origins are relatively unexplored. The majority of studies have focussed on the more derived passerine lineages and there is very little empirical information on the diversity of the MHC in basal passerine lineages. We undertook a study of MHC diversity and evolutionary relationships across seven species from four families (Climacteridae, Maluridae, Pardalotidae, Meliphagidae) that comprise a prominent component of the basal passerine lineages. We aimed to determine if highly polymorphic MHC paralogs have an early evolutionary origin within passerines or are a more derived feature of the infraorder Passerida. We identified 177 alleles of the MHC class II β exon 2 in seven basal passerine species, with variation in numbers of alleles across individuals and species. Overall, we found evidence of multiple gene loci, pseudoalleles, trans-species polymorphism and high allelic diversity in these basal lineages. Phylogenetic reconstruction of avian lineages based on MHC class II β exon 2 sequences strongly supported the monophyletic grouping of basal and derived passerine species. Our study provides evidence of a large number of highly polymorphic MHC paralogs in seven basal passerine species, with strong similarities to the MHC described in more derived passerine lineages rather than the simpler MHC in non-passerine lineages. These findings indicate an early evolutionary origin of highly polymorphic MHC paralogs in passerines and shed light on the evolutionary forces shaping the avian MHC.

Frequency of CYP450 enzyme gene polymorphisms in the Greek population: review of the literature, original findings and clinical significance.

PubMed

Ragia, Georgia; Giannakopoulou, Efstathia; Karaglani, Makrina; Karantza, Ioanna-Maria; Tavridou, Anna; Manolopoulos, Vangelis G

2014-01-01

The cytochrome P450 (CYP450) enzyme family is involved in the oxidative metabolism of many therapeutic drugs and various endogenous substrates. These enzymes are highly polymorphic. Prevalence of CYP450 enzyme gene polymorphisms vary among different populations and substantial inter- and intra-ethnic variability in frequency of CYP450 enzyme gene polymorphisms has been reported. This paper provides an overview and investigation of CYP450 genotypic and phenotypic reports published in the Greek population.

[Association of IL-1β-511T gene rs16944 polymorphism with febrile seizures].

PubMed

Ren, Xiao-Tun; Sun, Su-Zhen; Liu, Fang; Wang, Xiao-Ming

2014-02-01

Despite substantial research efforts worldwide, the role of inflammatory cytokine IL-1β in the onset of febrile seizures (FS) remains controversial. The aim of this study was to assess the relationship between rs16944 polymorphism of the IL-1β-511T gene and occurrence of simple FS in a sample of Han children in northern China. The IL-1β-511T gene rs16944 was genotyped by SNaPshot SNP technique in 141 FS children and 130 healthy control subjects. The genotypic and allelic frequencies in the two groups were comparatively analyzed. There were no significant differences in genotypic and allelic frequencies of rs16944 polymorphism of the IL-1β-511T gene between FS patients and control subjects (P>0.05).When the clinical data on A/A, A/G and G/G genotypes of the rs16944 polymorphism in FS patients, there was statistically significant difference in age of first onset (χ(2)=19.491, P<0.01), temperature of first onset (χ(2)=9.317, P<0.05) and family history of FS (χ(2)=26.798, P<0.01). There is no association between rs16944 polymorphism of the IL-1β-511T gene and the incidence of FS in Han children in Northern China. However, the differences in genotypes of this polymorphism might be associated with pathogenesis and prognosis of simple FS in the population studied.

High-efficiency cogeneration boiler bagasse-ash geochemistry and mineralogical change effects on the potential reuse in synthetic zeolites, geopolymers, cements, mortars, and concretes.

PubMed

Clark, Malcolm W; Despland, Laure M; Lake, Neal J; Yee, Lachlan H; Anstoetz, Manuela; Arif, Elisabeth; Parr, Jeffery F; Doumit, Philip

2017-04-01

Sugarcane bagasse ash re-utilisation has been advocated as a silica-rich feed for zeolites, pozzolans in cements and concretes, and geopolymers. However, many papers report variable success with the incorporation of such materials in these products as the ash can be inconsistent in nature. Therefore, understanding what variables affect the ash quality in real mills and understanding the processes to characterise ashes is critical in predicting successful ash waste utilisation. This paper investigated sugarcane bagasse ash from three sugar mills (Northern NSW, Australia) where two are used for the co-generation of electricity. Data shows that the burn temperatures of the bagasse in the high-efficiency co-generation boilers are much higher than those reported at the temperature measuring points. Silica polymorph transitions indicate the high burn temperatures of ≈1550 °C, produces ash dominated α -quartz rather than expected α-cristobilite and amorphous silica; although α-cristobilite, and amorphous silica are present. Furthermore, burn temperatures must be ≤1700 °C, because of the absence of lechatelierite where silica fusing and globulisation dominates. Consequently, silica-mineralogy changes deactivate the bagasse ash by reducing silica solubility, thus making bagasse ash utilisation in synthetic zeolites, geopolymers, or a pozzolanic material in mortars and concretes more difficult. For the ashes investigated, use as a filler material in cements and concrete has the greatest potential. Reported mill boiler temperatures discrepancies and the physical characteristics of the ash, highlight the importance of accurate temperature monitoring at the combustion seat if bagasse ash quality is to be prioritised to ensure a usable final ash product.

WDR1 and CLNK gene polymorphisms correlate with serum glucose and high-density lipoprotein levels in Tibetan gout patients.

PubMed

Lan, Bing; Chen, Peng; Jiri, Mutu; He, Na; Feng, Tian; Liu, Kai; Jin, Tianbo; Kang, Longli

2016-03-01

Current evidence suggests heredity and metabolic syndrome contributes to gout progression. Specifically, the WDR1 and CLNK genes may play a role in gout progression in European ancestry populations. However, no studies have focused on Chinese populations, especially Tibetan individuals. This study aims to determine whether variations in these two genes correlate with gout-related indices in Chinese-Tibetan gout patients. Eleven single-nucleotide polymorphisms in the WDR1 and CLNK genes were detected in 319 Chinese-Tibetan gout patients and 318 controls. We used one-way analysis of variance to evaluate the polymorphisms' effects on gout based on mean serum levels of metabolism indicators, such as albumin, glucose (GLU), triglycerides, cholesterol, high-density lipoproteins (HDL-C), creatinine, and uric acid, from fasting venous blood samples. All p values were Bonferroni corrected. Polymorphisms of the WDR1 and CLNK genes affected multiple risk factors for gout development. Significant differences in serum GLU levels were detected between different genotypic groups with WDRI polymorphisms rs4604059 (p = 0.005) and rs12498927 (p = 0.005). In addition, significant differences in serum HDL-C levels were detected between different genotypic groups with the CLNK polymorphism rs2041215 (p = 0.001). Polymorphisms of CLNK also affected levels of albumin, triglycerides, and creatinine. This study is the first to investigate and identify positive correlations between WDR1 and CLNK gene polymorphisms in Chinese-Tibetan populations. Our findings provide significant evidence for the effect of genetic polymorphisms on gout-related factors in Chinese-Tibetan populations.

Estrogen receptor alpha polymorphisms and the risk of prostate cancer development.

PubMed

Jurečeková, Jana; Babušíková, Eva; Kmeťová, Monika; Kliment, Ján; Dobrota, Dušan

2015-11-01

The main purpose of the study was to evaluate the effect of two polymorphisms in the estrogen receptor alpha, rs2077647 and rs3798577, on the development of prostate cancer, their correlation with selected clinical characteristics, as well as consideration of potential interactions between four estrogen receptor alpha polymorphisms (rs2077647, rs3798577, PvuII, XbaI). The study was performed using 395 patients with histologically verified prostate cancer and 253 healthy male controls. The CC genotype of rs2077647 was significantly associated with prostate cancer (OR = 1.61). No association was found between rs3798577 polymorphism and prostate cancer. After stratification of patients according to the age at diagnosis and Gleason score, we observed significant correlation between rs2077647 polymorphism and prostate cancer risk in patients diagnosed before the age of 60 as well as patients with Gleason score <7, while rs3798577 was significantly associated with prostate cancer risk development in patients older than 60 and with Gleason score ≥7. Double analysis of each combination of four studied polymorphisms showed that presence of at least three variant alleles was associated with prostate cancer risk in all combinations, while each containing rs3798577 was significantly associated with development of high-grade carcinomas. The present study suggests that rs2077647 polymorphism may be a risk factor for prostate cancer especially in patients diagnosed before the age of 60, while rs3798577 polymorphism could probably serve rather as promoting factor in combination with other polymorphisms in estrogen receptor alpha contributing preferably to development of high-grade carcinomas.

A Web-Based Genetic Polymorphism Learning Approach for High School Students and Science Teachers

ERIC Educational Resources Information Center

Amenkhienan, Ehichoya; Smith, Edward J.

2006-01-01

Variation and polymorphism are concepts that are central to genetics and genomics, primary biological disciplines in which high school students and undergraduates require a solid foundation. From 1998 through 2002, a web-based genetics education program was developed for high school teachers and students. The program included an exercise on using…

Shape and size variation on the wing of Drosophila mediopunctata: influence of chromosome inversions and genotype-environment interaction.

PubMed

Hatadani, Luciane Mendes; Klaczko, Louis Bernard

2008-07-01

The second chromosome of Drosophila mediopunctata is highly polymorphic for inversions. Previous work reported a significant interaction between these inversions and collecting date on wing size, suggesting the presence of genotype-environment interaction. We performed experiments in the laboratory to test for the joint effects of temperature and chromosome inversions on size and shape of the wing in D. mediopunctata. Size was measured as the centroid size, and shape was analyzed using the generalized least squares Procrustes superimposition followed by discriminant analysis and canonical variates analysis of partial warps and uniform components scores. Our findings show that wing size and shape are influenced by temperature, sex, and karyotype. We also found evidence suggestive of an interaction between the effects of karyotype and temperature on wing shape, indicating the existence of genotype-environment interaction for this trait in D. mediopunctata. In addition, the association between wing size and chromosome inversions is in agreement with previous results indicating that these inversions might be accumulating alleles adapted to different temperatures. However, no significant interaction between temperature and karyotype for size was found--in spite of the significant presence of temperature-genotype (cross) interaction. We suggest that other ecological factors--such as larval crowding--or seasonal variation of genetic content within inversions may explain the previous results.

Associations of polymorphisms in the Pit-1 gene with growth and carcass traits in Angus beef cattle.

PubMed

Zhao, Q; Davis, M E; Hines, H C

2004-08-01

The Pit-1 gene was studied as a candidate for genetic markers of growth and carcass traits. Angus beef cattle that were divergently selected for high- or low-blood serum IGF-I concentration were used in this study. The single-strand conformation polymorphism method was used to identify polymorphism in the Pit-1 gene including regions from intron 2 to exon 6. Two polymorphisms, Pit1I3H (HinfI) and Pit1I3NL (NlaIII), were detected in intron 3 of the Pit-1 gene. One polymorphism, Pit1I4N (BstNI), was found in intron 4, and a single nucleotide polymorphism, Pit1I5, was found in intron 5. The previously reported polymorphism in exon 6, Pit1E6H (HinfI), was also studied in 416 Angus beef cattle. Associations of the polymorphisms with growth traits, carcass traits, and IGF-I concentration were analyzed using a general linear model procedure. No significant associations were observed between these polymorphisms and growth and carcass traits.

Synthesis, Characterization, and Self-Controlled Orthorhombic to Tetragonal Polymorphic Transformation in BaTiO3 Nanoparticles

NASA Astrophysics Data System (ADS)

Ram, S.; Jana, A.; Kundu, T. K.

The phase formation and thermal-induced phase transformation are studied in BaTiO3 nanoparticles. 2 h of heating a polymer precursor at 550°C in air formed a single phase BaTiO3 of 15 nm average crystallite size D. The X-ray diffraction peaks are analyzed assuming a Pnma orthorhombic (o) crystal structure of lattice parameters a = 0.6435 nm, b = 0.5306 nm, and c = 0.8854 nm. The lattice volume V = 0.3023 nm3, with z = 4 formula units, yields a density ρ = 5.124 g/cm3. This is a new polymorph in comparison to well-known Pm3m tetragonal (t) structure, V = 0.0644 nm3 or ρ = 6.016 g/cm3 (z = 1). An o ↦ t transformation appears on heating at temperature as high as 650°C in air. A proposed model explains the transformation above a certain D value in terms of the Gibbs free energy. Unless heating above 750°C, the two phases coexist in a composite structure (D≤27 nm), with as much residual o-phase trace as ~28 vol%. As a function of temperature both the phases decrease in the V values up to 0.2975 and 0.0643 nm3 at 750°C respectively (0.0650 nm3 at 650°C). This is an important parameter for designing useful ferroelectric and other properties in a hybrid composite structure.

Creep of water ices at planetary conditions: A compilation

USGS Publications Warehouse

Durham, W.B.; Kirby, S.H.; Stern, L.A.

1997-01-01

Many constitutive laws for the flow of ice have been published since the advent of the Voyager explorations of the outer solar system. Conflicting data have occasionally come from different laboratories, and refinement of experimental techniques has led to the publication of laws that supersede earlier ones. In addition, there are unpublished data from ongoing research that also amend the constitutive laws. Here we compile the most current laboratory-derived flow laws for water ice phases I, II, III, V, and VI, and ice I mixtures with hard particulates. The rheology of interest is mainly that of steady state, and the conditions reviewed are the pressures and temperatures applicable to the surfaces and interiors of icy moons of the outer solar system. Advances in grain-size-dependent creep in ices I and II as well as in phase transformations and metastability under differential stress are also included in this compilation. At laboratory strain rates the several ice polymorphs are rheologically distinct in terms of their stress, temperature, and pressure dependencies but, with the exception of ice III, have fairly similar strengths. Hard particulates strengthen ice I significantly only at high particulate volume fractions. Ice III has the potential for significantly affecting mantle dynamics because it is much weaker than the other polymorphs and its region of stability, which may extend metastably well into what is nominally the ice II field, is located near likely geotherms of large icy moons. Copyright 1997 by the American Geophysical Union.

α-Ga2O3 grown by low temperature atomic layer deposition on sapphire

NASA Astrophysics Data System (ADS)

Roberts, J. W.; Jarman, J. C.; Johnstone, D. N.; Midgley, P. A.; Chalker, P. R.; Oliver, R. A.; Massabuau, F. C.-P.

2018-04-01

α-Ga2O3 is a metastable phase of Ga2O3 of interest for wide bandgap engineering since it is isostructural with α-In2O3 and α-Al2O3. α-Ga2O3 is generally synthesised under high pressure (several GPa) or relatively high temperature (∼500 °C). In this study, we report the growth of α-Ga2O3 by low temperature atomic layer deposition (ALD) on sapphire substrate. The film was grown at a rate of 0.48 Å/cycle, and predominantly consists of α-Ga2O3 in the form of (0001) -oriented columns originating from the interface with the substrate. Some inclusions were also present, typically at the tips of the α phase columns and most likely comprising ε-Ga2O3. The remainder of the Ga2O3 film - i.e. nearer the surface and between the α-Ga2O3 columns, was amorphous. The film was found to be highly resistive, as is expected for undoped material. This study demonstrates that α-Ga2O3 films can be grown by low temperature ALD and suggests the possibility of a new range of ultraviolet optoelectronic and power devices grown by ALD. The study also shows that scanning electron diffraction is a powerful technique to identify the different polymorphs of Ga2O3 present in multiphase samples.

Solid state stability and solubility of triethylenetetramine dihydrochloride.

PubMed

Henriet, Théo; Gana, Inès; Ghaddar, Carine; Barrio, Maria; Cartigny, Yohann; Yagoubi, Najet; Do, Bernard; Tamarit, Josep-Lluis; Rietveld, Ivo B

2016-09-10

The API triethylenetetramine dihydrochloride used as an alternative treatment of Wilson's disease is sensitive to water and it exhibits polymorphism. As this may become an issue for the drug formulation, the physical stability has been studied by differential scanning calorimetry, high-pressure thermal analysis, dynamic vapor sorption, and X-ray diffraction as a function of temperature. In addition, high-pressure liquid chromatography and mass spectrometry have been used to study the purity and chemical stability of the API. A pressure-temperature phase diagram of the pure compound has been constructed and it can be concluded that form II is monotropic in relation to form I, which is the only stable solid. The solubilities of the different solid forms have been determined with the help of a temperature - composition phase diagram. The API is very soluble, at 20° C about 10% of the saturated solution with respect to the dihydrate consists of API and the solubility of the pure form I is twice as high. Moreover, it has been shown that at 20°C, a relative humidity above 40% induces the formation of the dihydrate and at 70% a saturated solution appears. At higher temperatures, the formation of the dihydrate appears at lower relative humidity values. A clear link has been established between the API's chemical stability, its physical stability and the relative humidity in the air. Humidity levels above 40% are detrimental to the quality of the API. Copyright © 2016 Elsevier B.V. All rights reserved.

Biomarker sensing using nanostructured metal oxide sensors

NASA Astrophysics Data System (ADS)

Kalyanasundaram, Krithika

Resistive Chemical sensors are those gas sensitive materials, typically semiconducting metal oxides, that change their electrical properties in response to a change in the ambient. The key features of a chemosensor are sensitivity, selectivity, response time and sensor stability. The hypothesis of this work is that, since metal oxides are polymorphic compounds, the crystal structure of the specific polymorph determines the relative gas selectivity of the material; also that the morphology of the sensing element determines the gas sensitivity limit. This work focuses on the synthesis of nanostructured metal oxides for chemosensors used in selective 'biomarker' detection. Biomarkers are chemical compounds, products of human metabolism which act as specific disease markers. The biomarkers studied in this work include NO, isoprene, NH3, ethanol and acetone which can all be found in exhaled human breath and which allow the non-invasive detection of a range of diseases. Sensors based on three different metal oxides-MoO3, WO 3, and TiO2 were fabricated using sol-gel, electrospinning and spray pyrolysis techniques and tested both as single elements and in an array configuration (electronic nose). The effects of the processing method used, grain size and shape and crystal phase of the material produced, and temperature effects of postsynthesis processing and sensing have been evaluated. Structural characterization has been carried out using X-Ray Diffraction, Scanning and High Resolution Transmission Electron Microscopy, while spectroscopic measurements using XPS, Raman and In-situ FTIR provide valuable information about the surface-analyte interactions. This work has shown that the use of monoclinic polymorph of WO3 yields a selective response to NO, while the other phase of the same oxide give a non-selective chemical response. The orthorhombic phase of MoO 3 exhibits specificity to NH3. An explanation for the variable sensing properties is given based on the gas interactions with the given polymorph involving adsorption/reaction processes. Another major finding of this work is that there was orders of magnitude increase in gas sensitivity when high aspect ratio nanowires as opposed to nanoparticles of the same diameter were used.

Characterization of polyploid wheat genomic diversity using a high-density 90 000 single nucleotide polymorphism array

USDA-ARS?s Scientific Manuscript database

High-density single nucleotide polymorphism (SNP) genotyping chips are a powerful tool for studying genomic patterns of diversity, inferring ancestral relationships among individuals in populations and studying marker-trait associations in mapping experiments. We developed a genotyping array includ...

Use of palm mid-fraction in dark chocolate as base filling centre at different storage temperatures.

PubMed

Jinap, S; Ali, A A; Man, Y B; Suria, A M

2000-11-01

Dark chocolates filled with palm mid-fraction (PMF) were stored at different temperatures to evaluate the physical and chemical changes. Storage at low temperature (18 degrees C) reduces the PMF migration to negligible extent. Higher storage temperatures (30 and 35 degrees C) increased the PMF migration from the filling centre into the chocolate coating. As a consequence of fat migration, fatty acid composition, triglyceride composition, hardness, solid fat content, melting point and polymorphic structure changed, leading to bloom formation, which started by fat migration and was influenced by recrystallization tendency within the chocolate coating.

Structural and conformational properties of 1-decyl-3-methylimidazolium tetrafluoroborate under high pressure

NASA Astrophysics Data System (ADS)

Chen, Liucheng; Li, Haining; Zhu, Xiang; Su, Lei; Yang, Kun; Yuan, Chaosheng; Yang, Guoqiang; Li, Xiaodong

2017-06-01

In situ crystalization of 1-decyl-3-methylimidazolium tetrafluoroborate ([C10MIM][BF4]) from melt has been investigated under high pressure up to 3.4 GPa at room temperature by using Raman spectroscopy and synchrotron X-ray diffraction measurement. Raman spectral analysis indicated that [C10MIM][BF4] experienced two successive phase transitions at about 0.3 GPa and 1.6 GPa. And the polymorphism was also discussed in view of the conformational isomerism of [C10MIM]+ cation between gauche and trans conformers. Notably, liquid-crystal and crystal-crystal phase transitions were further confirmed by synchrotron X-ray diffraction measurement. Moreover, it also indicated that high structural flexibility of the cations with long alkyl chain might have effect on the degree of disorder of pressure-induced crystallization for ionic liquids.

Plasminogen activator inhibitor-1 4G/5G promoter polymorphism and coagulation factor VII Arg353-->Gln polymorphism in Korean patients with coronary artery disease.

PubMed Central

Song, J.; Yoon, Y. M.; Jung, H. J.; Hong, S. H.; Park, H.; Kim, J. Q.

2000-01-01

An increased risk for arterial thrombosis is associated with high plasma levels of coagulation and fibrinolytic factors such as PAI-1 and FVII. In this study, the 4G/5G polymorphism in the promoter of PAI-1 gene and Arg353-->Gln polymorphism in the FVII gene were analysed in 139 normal adults and 158 patients with coronary artery disease (CAD), and their association with plasma lipid traits was investigated. There were no significant differences in the allele frequencies of PAI-1 and FVII polymorphisms between control and patient groups. The allelic distributions of both polymorphisms in Koreans were similar to those in Japanese but significantly different from those in Caucasians. In the CAD group, the 4G homozygotes of PAI-1 polymorphism showed significantly higher levels of total (p=0.0250) and LDL cholesterol (p=0.0335) with individuals having other genotypes. However, FVII polymorphism showed no association with lipid levels. In conclusion, the 4G/5G PAI-1 promoter polymorphism and Arg353-->Gln FVII polymorphism are not major genetic risk factors for CAD in Koreans. However, 4G allele of PAI-1 polymorphism revealed to be associated with the levels of cholesterol, especially LDL cholesterol levels in CAD patients. PMID:10803689

rs11613352 polymorphism (TT genotype) associates with a decrease of triglycerides and an increase of HDL in familial hypercholesterolemia patients.

PubMed

Aledo, Rosa; Padró, Teresa; Mata, Pedro; Alonso, Rodrigo; Badimon, Lina

2015-04-01

Recent genome-wide association studies have identified a locus on chromosome 12q13.3 associated with plasma levels of triglyceride and high-density lipoprotein cholesterol, with rs11613352 being the lead single nucleotide polymorphism in this genome-wide association study locus. The aim of the study is to investigate the involvement of rs11613352 in a population with high cardiovascular risk due to familial hypercholesterolemia. The single nucleotide polymorphism was genotyped by Taqman(®) assay in a cohort of 601 unrelated familial hypercholesterolemia patients and its association with plasma triglyceride and high-density lipoprotein cholesterol levels was analyzed by multivariate methods based on linear regression. Minimal allele frequency was 0.17 and genotype frequencies were 0.69, 0.27, and 0.04 for CC, CT, and TT genotypes, respectively. The polymorphism is associated in a recessive manner (TT genotype) with a decrease in triglyceride levels (P=.002) and with an increase in high-density lipoprotein cholesterol levels (P=.021) after adjusting by age and sex. The polymorphism rs11613352 may contribute to modulate the cardiovascular risk by modifying plasma lipid levels in familial hypercholesterolemia patients. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Polymorphisms in the oxytocin receptor gene are associated with the development of psychopathy.

PubMed

Dadds, Mark R; Moul, Caroline; Cauchi, Avril; Dobson-Stone, Carol; Hawes, David J; Brennan, John; Urwin, Ruth; Ebstein, Richard E

2014-02-01

The co-occurrence of child conduct problems (CPs) and callous-unemotional (CU) traits confers risk for psychopathy. The oxytocin (OXT) system is a likely candidate for involvement in the development of psychopathy. We tested variations in the OXT receptor gene (OXTR) in CP children and adolescents with varying levels of CU traits. Two samples of Caucasian children, aged 4-16 years, who met DSM criteria for disruptive behavior problems and had no features of autism spectrum disorder, were stratified into low versus high CU traits. Measures were the frequencies of nine candidate OXTR polymorphisms (single nucleotide polymorphisms). In Sample 1, high CU traits were associated with single nucleotide polymorphism rs1042778 in the 3' untranslated region of OXTR and the CGCT haplotype of rs2268490, rs2254298, rs237889, and rs13316193. The association of rs1042778 was replicated in the second rural sample and held across gender and child versus adolescent age groups. We conclude that polymorphic variation of the OXTR characterizes children with high levels of CU traits and CPs. The results are consistent with a hypothesized role of OXT in the developmental antecedents of psychopathy, particularly the differential amygdala activation model of psychopathic traits, and add genetic evidence that high CU traits specify a distinct subgroup within CP children.

Synchrotron x-ray high energy PDF and tomography studies for gallium melts under high-pressure conditions

NASA Astrophysics Data System (ADS)

Liu, H.; Liu, L. L.; Li, R.; Li, L.

2015-12-01

Liquid gallium exhibits unusual and unique physical properties. A rich polymorphism and metastable modifications of solid Ga have been discovered and a number of studies of liquid gallium under high pressure conditions were reported. However, some fundamental properties, such as the equation of state (EoS) of Ga melt under extreme conditions remain unclear. To compare to the previous reports, we performed the pair distribution function (PDF) study using diamond anvil cell, in which synchrotron high-energy x-ray total scattering data, combined with reverse Monte Carlo simulation, was used to study the microstructure and EoS of liquid gallium under high pressure at room temperature conditions. The EoS of Ga melt, which was measured from synchrotron x-ray tomography method at room temperature, was used to avoid the potential relatively big errors for the density estimation from the reverse Monte Carlo simulation with the mathematical fit to the measured structure factor data. The volume change of liquid gallium have been studied as a function of pressure and temperature up to 5 GPa at 370 K using synchrotron x-ray microtomography combined with energy dispersive x-ray diffraction (EDXRD) techniques using Drickamer press. The directly measured P-V-T curves were obtained from 3D tomography reconstruction data. The existence of possible liquid-liquid phase transition regions is proposed based on the abnormal compressibility and local structure change in Ga melts.

Methane- and sulfur-metabolizing microbial communities dominate the Lost City hydrothermal field ecosystem.

PubMed

Brazelton, William J; Schrenk, Matthew O; Kelley, Deborah S; Baross, John A

2006-09-01

Hydrothermal venting and the formation of carbonate chimneys in the Lost City hydrothermal field (LCHF) are driven predominantly by serpentinization reactions and cooling of mantle rocks, resulting in a highly reducing, high-pH environment with abundant dissolved hydrogen and methane. Phylogenetic and terminal restriction fragment length polymorphism analyses of 16S rRNA genes in fluids and carbonate material from this site indicate the presence of organisms similar to sulfur-oxidizing, sulfate-reducing, and methane-oxidizing Bacteria as well as methanogenic and anaerobic methane-oxidizing Archaea. The presence of these metabolic groups indicates that microbial cycling of sulfur and methane may be the dominant biogeochemical processes active within this ultramafic rock-hosted environment. 16S rRNA gene sequences grouping within the Methylobacter and Thiomicrospira clades were recovered from a chemically diverse suite of carbonate chimney and fluid samples. In contrast, 16S rRNA genes corresponding to the Lost City Methanosarcinales phylotype were found exclusively in high-temperature chimneys, while a phylotype of anaerobic methanotrophic Archaea (ANME-1) was restricted to lower-temperature, less vigorously venting sites. A hyperthermophilic habitat beneath the LCHF may be reflected by 16S rRNA gene sequences belonging to Thermococcales and uncultured Crenarchaeota identified in vent fluids. The finding of a diverse microbial ecosystem supported by the interaction of high-temperature, high-pH fluids resulting from serpentinization reactions in the subsurface provides insight into the biogeochemistry of what may be a pervasive process in ultramafic subseafloor environments.

Highly sensitive chemiluminescent point mutation detection by circular strand-displacement amplification reaction.

PubMed

Shi, Chao; Ge, Yujie; Gu, Hongxi; Ma, Cuiping

2011-08-15

Single nucleotide polymorphism (SNP) genotyping is attracting extensive attentions owing to its direct connections with human diseases including cancers. Here, we have developed a highly sensitive chemiluminescence biosensor based on circular strand-displacement amplification and the separation by magnetic beads reducing the background signal for point mutation detection at room temperature. This method took advantage of both the T4 DNA ligase recognizing single-base mismatch with high selectivity and the strand-displacement reaction of polymerase to perform signal amplification. The detection limit of this method was 1.3 × 10(-16)M, which showed better sensitivity than that of most of those reported detection methods of SNP. Additionally, the magnetic beads as carrier of immobility was not only to reduce the background signal, but also may have potential apply in high through-put screening of SNP detection in human genome. Copyright © 2011 Elsevier B.V. All rights reserved.

Shock-induced decomposition of a high density glass (ZF6)

NASA Astrophysics Data System (ADS)

Zhou, Xianming; Liu, Xun; Li, Jiabo; Li, Jun; Cao, Xiuxia

2011-07-01

The dynamic high-pressure behavior of a high density glass (ZF6) was investigated in this study. The Hugoniot data, shock temperature (TH) and release sound velocity (C) of ZF6 were measured by a time-resolved multi-channel pyrometer in the shock pressure (PH) range of 50-170 GPa. The Hugoniot data is in accord with the Los Alamos Scientific Laboratory (LASL) shock Hugoniot data and shows a good linearity over 21 GPa. Polymorphic phase transitions were identified by the kinks in the measured TH-PH and C-PH relationships. The onset pressures of the transformations are ˜75 and ˜128 GPa, respectively. A thermodynamic calculation suggests that the phase transition at 75 GPa is its disproportionation to massicot (high pressure phase of PbO) and melted silica while the transition at 128 GPa is from the melting of massicot.

Association between angiotensin II receptor gene polymorphism and serum angiotensin converting enzyme (SACE) activity in patients with sarcoidosis.

PubMed

Takemoto, Y; Sakatani, M; Takami, S; Tachibana, T; Higaki, J; Ogihara, T; Miki, T; Katsuya, T; Tsuchiyama, T; Yoshida, A; Yu, H; Tanio, Y; Ueda, E

1998-06-01

Serum angiotensin converting enzyme (SACE) is considered to reflect disease activity in sarcoidosis. SACE activity is increased in many patients with active sarcoid lesions. The mechanism for the increased SACE activity in this disease has not been clarified. ACE insertion/deletion (I/D) gene polymorphism has been reported to have an association with SACE levels in sarcoidosis, but no evidence of an association between angiotensin II receptor gene polymorphism and SACE in this disease has been found. A study of the association of angiotensin II receptor gene polymorphisms with sarcoidosis was therefore undertaken. ACE (I/D), angiotensin II type 1 receptor (AGTR1), and angiotensin II type 2 receptor (AGTR2) gene polymorphisms were investigated by polymerase chain reaction (PCR) and SACE levels were measured in three groups of patients: those with sarcoidosis or tuberculosis and normal controls. There was no difference in allele frequency of AGTR1 and AGTR2 polymorphism among the three groups. Neither AGTR1 nor AGTR2 polymorphisms were associated with sarcoidosis. SACE activity was higher in patients with sarcoidosis with the AGTR1 A/C genotype than in others. However, this tendency was not detected in patients with tuberculosis. The AGTR1 allele C is associated with high activity of SACE in patients with sarcoidosis. It is another predisposing factor for high levels of SACE in patients with sarcoidosis and is considered to be an independent factor from the ACE D allele for high levels of SACE in sarcoidosis. This fact could be one of the explanations for the increased SACE activity in sarcoidosis.

Structural, thermodynamic, and kinetic aspects of the trimorphism of hydrocortisone.

PubMed

Suitchmezian, Viktor; Jess, Inke; Näther, Christian

2008-10-01

Hydrocortisone was investigated for polymorphism and pseudopolymorphism and three different polymorphic modifications (I-III) and one 2-propanol solvate were found. Forms I and III crystallize in the orthorhombic space group P2(1)2(1)2(1), whereas form II and the 2-propanol solvate crystallize monoclinic in space group P2(1). In all the modifications the molecules are connected by intermolecular O--H...O hydrogen bonding. In the 2-propanol solvate, channels are formed in which the solvent molecules are embedded. Solvent-mediated conversion experiments reveal that the commercially available form I represents the thermodynamically most stable modification at room temperature, whereas forms II and III are metastable. On heating, form III transforms into form II in an endothermic reaction, which shows that an enantiotropic relationship exists between these forms. Form I exhibits the highest melting point and the highest heat of fusion and thus represents the thermodynamically most stable form over the whole temperature range. DSC measurements indicate that form I behaves monotropic to forms II and III. Desolvation of the 2-propanol solvate at higher temperatures results in a transformation into form II, whereas the removal of 2-propanol at room temperature and in vacuum reduced pressure leads to the formation of form III. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

Thermoregulation and microhabitat choice in the polymorphic asp viper (Vipera aspis).

PubMed

Muri, Daniele; Schuerch, Johan; Trim, Naïke; Golay, Joaquim; Baillifard, Alexandre; El Taher, Athimed; Dubey, Sylvain

2015-10-01

In ectotherms, thermoregulation strongly depends on environmental conditions, as well as on intrinsic factors, such as skin colour. Indeed, due to its physical properties, melanin pigments allow melanistic morphs to benefit of a more efficient thermoregulation compared to non-melanistic ones. Despite thermal benefits of melanism have often been highlighted under experimental conditions, such field data remain scarce. In this study, we investigated the influence of colouration on body temperature and microhabitat choice in a montane population of colour polymorphic asp viper (Vipera aspis) characterized by a strong presence of melanism (64%). Results highlighted a difference in internal body temperature, but only within gravid females, with melanistic individuals having higher body temperatures compared to non-melanistic ones. No differences were found when considering both sexes. We also showed that melanistic and non-melanistic vipers were found in different microhabitat types, i.e. melanistic snakes used areas marked by a scarcer sun exposure and by higher vegetation cover compared to non-melanistic ones. This result has important implications. Indeed, besides providing a possible explanation for the lack of difference in body temperature (except for gravid females), it confirms that melanistic individuals can potentially use their efficient thermoregulation in order to inhabit less exposed and thermally unfavourable microhabitats. Copyright © 2015 Elsevier Ltd. All rights reserved.

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak P.; Gump, Jared C.

2006-07-01

Explosive formulations with reduced-sensitivity RDX showed reduced shock sensitivity using Naval Ordnance Laboratory (NOL) Large Scale Gap Test, compared with similar formulations using standard RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light on the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. I-RDX®, a form of reduced- sensitivity RDX was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transform IR (FTIR). The pressure dependence of the Raman mode frequencies of I-RDX® was determined and compared with that of standard RDX. The behavior of I-RDX® near the pressure at which standard RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph is presented.

Glass Transitions in a Monatomic Liquid with Two Glassy States

NASA Astrophysics Data System (ADS)

Gordon, Andrew; Giovambattista, Nicolas

2014-04-01

We perform out-of-equilibrium molecular dynamics simulations of a monatomic liquid that exhibits liquid and glass polymorphism, with two distinct glasses, low- (LDA) and high-density (HDA) amorphous solids. By performing isobaric heating simulations of LDA and HDA at different pressures, we determine (a) the glass transition temperature of LDA and HDA, TgLDA(P) and TgHDA(P), as well as (b) the corresponding glass-glass transformation temperatures, TLDA-HDA(P) and THDA-LDA(P). It is found that TgLDA(P) is anomalous; i.e., it decreases with increasing pressure, while TgHDA(P) increases with increasing pressure. Interestingly, the TgLDA(P) and TLDA-HDA(P) loci, as well as the TgHDA(P) and THDA-LDA(P) loci, constitute smooth single lines in the P -T plane, suggesting that heating-induced glass-glass and glass transitions are related. We discuss the present results in the context of water experiments and simulations.

Thermophysical properties of liquid UO2, ZrO2 and corium by molecular dynamics and predictive models

NASA Astrophysics Data System (ADS)

Kim, Woong Kee; Shim, Ji Hoon; Kaviany, Massoud

2017-08-01

Predicting the fate of accident-melted nuclear fuel-cladding requires the understanding of the thermophysical properties which are lacking or have large scatter due to high-temperature experimental challenges. Using equilibrium classical molecular dynamics (MD), we predict the properties of melted UO2 and ZrO2 and compare them with the available experimental data and the predictive models. The existing interatomic potential models have been developed mainly for the polymorphic solid phases of these oxides, so they cannot be used to predict all the properties accurately. We compare and decipher the distinctions of those MD predictions using the specific property-related autocorrelation decays. The predicted properties are density, specific heat, heat of fusion, compressibility, viscosity, surface tension, and the molecular and electronic thermal conductivities. After the comparisons, we provide readily usable temperature-dependent correlations (including UO2-ZrO2 compounds, i.e. corium melt).

A new polymorph of 4'-hydroxyvalerophenone revealed by thermoanalytical and X-ray diffraction studies

NASA Astrophysics Data System (ADS)

Lopes, Cátia S. D.; Bernardes, Carlos E. S.; Piedade, M. Fátima M.; Diogo, Hermínio P.; da Piedade, Manuel E. Minas

2017-04-01

A new polymorph of 1-(4-hydroxyphenyl)pentan-1-one (4'-hydroxyvalerophenone, HVP) was identified by using differential scanning calorimetry, hot stage microscopy, and X-ray powder diffraction. This novel crystal form (form II) was obtained by crystallization from melt. It has a fusion temperature of T fus = 324.3 ± 0.2 K and an enthalpy of fusion Δfus H m o = 18.14±0.18 kJ·mol-1. These values are significantly lower than those observed for the previously known phase (form I, monoclinic, space group P21/ c, T fus = 335.6 ± 0.7 K; Δfus H m o = 26.67±0.04 kJ·mol-1), which can be prepared by crystallization from ethanol. The results here obtained, therefore, suggest that form I is thermodynamically more stable than the newly identified form II and, furthermore, that the two polymorphs are monotropically related.

X-ray crystallography, an essential tool for the determination of thermodynamic relationships between crystalline polymorphs.

PubMed

Céolin, R; Rietveld, I-B

2016-01-01

After a short review of the controversies surrounding the discovery of crystalline polymorphism in relation to our present day understanding, the methods of how to solve the stability hierarchy of different polymorphs will be briefly discussed. They involve either theoretical calculations, or, more commonly, experimental methods based on classical thermodynamics. The experimental approach is mainly carried out using heat-exchange data associated to the transition of one form into another. It will be demonstrated that work-related data associated to the phase transition should be taken into account and the role of X-ray crystallography therein will be discussed. X-ray crystallography has become increasingly precise and can nowadays provide specific volumes and their differences as a function of temperature, and also as a function of pressure, humidity, and time. Copyright © 2015 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

Genetic Variants in TAP Are Associated with High-Grade Cervical Neoplasia

PubMed Central

Einstein, Mark H.; Leanza, Suzanne; Chiu, Lydia G.; Schlecht, Nicolas F.; Goldberg, Gary L.; Steinberg, Bettie M.; Burk, Robert D.

2018-01-01

Purpose The transporter associated with antigen processing (TAP) is essential in assembling MHC-I proteins. Human papillomavirus (HPV) evades immune recognition by decreasing class I MHC cell surface expression through down-regulation of TAP1 levels. Consistent with heterogeneity in MHC expression is the individual variability in clearing detectable HPV infections. Genetic polymorphisms in TAP genes may affect protein structure, function, and the ability to clear HPV infection. Experimental Design Case-control study of women with cervical intraepithelial neoplasia (CIN) II or III (n = 114) and women without high-grade CIN (n = 366). Five nonsynonymous single nucleotide polymorphisms (SNP) in TAP1 and TAP2 were genotyped using DNA collected in cervicovaginal lavage samples using microsphere array technology (Luminex ×MAP). HPV typing was done using a PCR-based system with MY09/MY11 primers. TAP1 and TAP2 SNPs were validated by direct sequencing. Results Differences in allele distribution between women with high-grade cervical neoplasia and women without was seen for TAP1 I333V (P = 0.02) and TAP1 D637G (p = 0.01).The odds ratios (OR) for CIN III were significantly lower among carriers of the TAP1 I333V polymorphism (OR, 0.28; 95% confidence interval, 0.1-0.8), and TAP1 D637G polymorphism (OR, 0.27; 95% confidence interval, 0.1-0.7). These associations remained significant even after restricting the evaluation to women who were positive for high-risk HPV types. Conclusions In addition to the down-regulation of MHC-1 by oncogenic HPV, HPV pathogenesis might be facilitated by polymorphisms in the TAP proteins. Identifying TAP polymorphisms may potentially be used to identify women less susceptible to progression to high-grade CIN and cervical cancer. PMID:19188174

Development of highly polymorphic simple sequence repeat markers using genome-wide microsatellite variant analysis in Foxtail millet [Setaria italica (L.) P. Beauv.

PubMed Central

2014-01-01

Background Foxtail millet (Setaria italica (L.) Beauv.) is an important gramineous grain-food and forage crop. It is grown worldwide for human and livestock consumption. Its small genome and diploid nature have led to foxtail millet fast becoming a novel model for investigating plant architecture, drought tolerance and C4 photosynthesis of grain and bioenergy crops. Therefore, cost-effective, reliable and highly polymorphic molecular markers covering the entire genome are required for diversity, mapping and functional genomics studies in this model species. Result A total of 5,020 highly repetitive microsatellite motifs were isolated from the released genome of the genotype 'Yugu1’ by sequence scanning. Based on sequence comparison between S. italica and S. viridis, a set of 788 SSR primer pairs were designed. Of these primers, 733 produced reproducible amplicons and were polymorphic among 28 Setaria genotypes selected from diverse geographical locations. The number of alleles detected by these SSR markers ranged from 2 to 16, with an average polymorphism information content of 0.67. The result obtained by neighbor-joining cluster analysis of 28 Setaria genotypes, based on Nei’s genetic distance of the SSR data, showed that these SSR markers are highly polymorphic and effective. Conclusions A large set of highly polymorphic SSR markers were successfully and efficiently developed based on genomic sequence comparison between different genotypes of the genus Setaria. The large number of new SSR markers and their placement on the physical map represent a valuable resource for studying diversity, constructing genetic maps, functional gene mapping, QTL exploration and molecular breeding in foxtail millet and its closely related species. PMID:24472631

Development of highly polymorphic simple sequence repeat markers using genome-wide microsatellite variant analysis in Foxtail millet [Setaria italica (L.) P. Beauv].

PubMed

Zhang, Shuo; Tang, Chanjuan; Zhao, Qiang; Li, Jing; Yang, Lifang; Qie, Lufeng; Fan, Xingke; Li, Lin; Zhang, Ning; Zhao, Meicheng; Liu, Xiaotong; Chai, Yang; Zhang, Xue; Wang, Hailong; Li, Yingtao; Li, Wen; Zhi, Hui; Jia, Guanqing; Diao, Xianmin

2014-01-28

Foxtail millet (Setaria italica (L.) Beauv.) is an important gramineous grain-food and forage crop. It is grown worldwide for human and livestock consumption. Its small genome and diploid nature have led to foxtail millet fast becoming a novel model for investigating plant architecture, drought tolerance and C4 photosynthesis of grain and bioenergy crops. Therefore, cost-effective, reliable and highly polymorphic molecular markers covering the entire genome are required for diversity, mapping and functional genomics studies in this model species. A total of 5,020 highly repetitive microsatellite motifs were isolated from the released genome of the genotype 'Yugu1' by sequence scanning. Based on sequence comparison between S. italica and S. viridis, a set of 788 SSR primer pairs were designed. Of these primers, 733 produced reproducible amplicons and were polymorphic among 28 Setaria genotypes selected from diverse geographical locations. The number of alleles detected by these SSR markers ranged from 2 to 16, with an average polymorphism information content of 0.67. The result obtained by neighbor-joining cluster analysis of 28 Setaria genotypes, based on Nei's genetic distance of the SSR data, showed that these SSR markers are highly polymorphic and effective. A large set of highly polymorphic SSR markers were successfully and efficiently developed based on genomic sequence comparison between different genotypes of the genus Setaria. The large number of new SSR markers and their placement on the physical map represent a valuable resource for studying diversity, constructing genetic maps, functional gene mapping, QTL exploration and molecular breeding in foxtail millet and its closely related species.

APOE, MTHFR, LDLR and ACE polymorphisms among Angami and Lotha Naga populations of Nagaland, India.

PubMed

Murry, Benrithung; Vakha, Neikethono; Achoubi, Nongthombam; Sachdeva, M P; Saraswathy, K N

2011-12-01

Several common polymorphisms in the ApoE, ACE, MTHFR and LDLR genes have been implicated in the pathogenesis of common complex diseases across world populations. This study investigates the prevalence of five known and clinically important common polymorphisms in Angami and Lotha Naga populations. A total of 112 unrelated healthy volunteers (52 Lotha Nagas and 60 Angami Nagas) participated in the study. All the five genes were found to be polymorphic in the studied populations. The Lotha Nagas displayed higher mutant allele frequencies than the Angami Nagas except for the T allele frequency of the AvaII polymorphism of the LDLR gene, though chi square did not reveal any significant population differences by genotypes. In view of the relatively high mutant allele frequencies in both the populations, they are likely to be at a high risk of developing various complex diseases as they shift from an active and rigorous lifestyle to a more sedentary one.

Magnetism of Carbonados

NASA Technical Reports Server (NTRS)

Kletetschka, G.; Taylor, P. T.; Wasilewski, P. J.

1999-01-01

Carbonados are porous polycrystalline (with crystal sizes up to 100 micrometer) diamonds. Carbonado is found only in alluvial deposits in Bahia, Brazil and in the Central African Republic (CAR). Alluvial deposit host is 1.5 Ga while the carbonados are between 2.6 - 3.8 Ga. The process of fusing the carbonado microcrystals together is not fully understood, partly due to fact that the origin of these carbonado, is not known. Several modes of origins are proposed for carbonado. First, a crustal origin. Carbonados have a light carbon and helium isotopic signature. They contain an enrichment of the rare-earth elements (REE). Carbonados have tightly trapped atmospheric noble gases and contain an evidence of high He content despite the carbonado expected depletion of He at mantle temperatures. Carbonados have high porosity incompatible with high pressure mantle conditions. Second, a mantle origin is proposed based on similar REE pattern to kimberlites. The presence of nitrogen platelet (by IR spectra) indicates high temperature origin and syngenetic inclusions of rutile, ilmenite, and magnetite indicates high pressure and high temperature conditions consistent with mantle origin as well. Third, it is proposed that carbonado diamonds are a result of early impacts into crustal rocks. This is indicated by the rare and controversial occurrence of high pressure diamond polymorph, londsdaleite, frequently found in diamonds from meteorite impact sites, and by observation of planar deformation features, possibly indicating shock events. Finally, it is suggested that carbonados have an extraterrestrial origin, as indicated by a long term annealing based on observation of a zero-phonon line, attributed to paired nitrogen atoms in association with a vacancy.

Improved tabletability after a polymorphic transition of delta-mannitol during twin screw granulation.

PubMed

Vanhoorne, V; Bekaert, B; Peeters, E; De Beer, T; Remon, J-P; Vervaet, C

2016-06-15

In most formulations processed via continuous twin screw granulation microcrystalline cellulose (MCC) and/or lactose are used as excipients, but mannitol is also a preferred excipient for wet granulation and tableting due to its non-hygroscopicity and inertness. Therefore, the aim of the current study was to investigate the influence of process parameters on critical quality attributes of granules (moisture content, solid state, morphology, size distribution, specific surface area, friability, flowability and hygroscopicity) and tablets (tensile strength and friability) after twin screw granulation of δ-mannitol. The δ-polymorph was selected since a moisture-induced transformation to β-mannitol was observed during batch wet granulation, which exhibited a unique morphology with a large surface area and improved tabletability. A full factorial experimental design was performed, varying screw speed (400-900rpm), granulation temperature (25-40°C), number of kneading elements (6 or 12) and liquid-to-solid (L/S) ratio, on the granulation unit of a ConsiGma™-25 line (a continuous powder-to-tablet manufacturing system). After tray drying the granules were milled and tableted. The results showed that the polymorphic transition from δ- to β-mannitol also occurred during twin screw granulation, although the residence time and L/S ratios were much lower in continuous twin screw granulation compared to batch processing. However, the polymorphic transition was not complete in all experiments and depended on the L/S ratio, screw speed and number of kneading elements. Nevertheless all granules exhibited the unique morphology linked to the polymorphic transition and had a superior tabletability compared to granules produced with β-mannitol as starting material. This was attributed to enhanced plastic deformation of the granules manufactured using δ-mannitol as starting material. In addition, it was concluded that mannitol was granulated via a different mechanism than other, less-soluble, excipients (e.g. lactose, microcrystalline cellulose) due to its high solubility and dissolution rate as the influence of process parameters on the mannitol granule characteristics was different. Copyright © 2016 Elsevier B.V. All rights reserved.

Polymorphisms in the bovine HSP90AB1 gene are associated with heat tolerance in Thai indigenous cattle.

PubMed

Charoensook, Rangsun; Gatphayak, Kesinee; Sharifi, Ahmad Reza; Chaisongkram, Chavin; Brenig, Bertram; Knorr, Christoph

2012-04-01

Heat shock proteins act as molecular chaperones that have preferentially been transcribed in response to severe perturbations of the cellular homeostasis such as heat stress. Here the traits respiration rate (RR), rectal temperature (RT), pack cell volume (PCV) and the individual heat tolerance coefficient (HTC) were recorded as physiological responses on heat stress (environmental temperatures) in Bos taurus (crossbred Holstein Friesian; HF) and B. indicus (Thai native cattle: White Lamphun; WL and Mountain cattle; MT) animals (n = 47) in Thailand. Polymorphisms of the heat shock protein 90-kDa beta gene (HSP90AB1) were evaluated by comparative sequencing. Nine single nucleotide polymorphisms (SNP) were identified, i.e. three in exons 10 and 11, five in introns 8, 9, 10 and 11, and one in the 3'UTR. The exon 11 SNP g.5082C>T led to a missense mutation (alanine to valine). During the period of extreme heat (in the afternoon) RR and RT were elevated in each of the three breeds, whereas the PCV decreased. Mountain cattle and White Lamphun heifers recorded significantly better physiologic parameters (p < 0.05) in all traits considered, including or particularly HTC than Holstein Friesian heifers. The association analysis revealed that the T allele at SNP g.4338T>C within intron 3 improved the heat tolerance (p < 0.05). Allele T was exclusively found in White Lamphun animals and to 84% in Mountain cattle. Holstein Friesian heifers revealed an allele frequency of only 18%. Polymorphisms within HSP90AB1 were not causative for the physiological responses; however, we propose that they should at least be used as genetic markers to select appropriate breeds for hot climates.

Matrix isolation studies of carbonic acid--the vapor phase above the β-polymorph.

PubMed

Bernard, Jürgen; Huber, Roland G; Liedl, Klaus R; Grothe, Hinrich; Loerting, Thomas

2013-05-22

Twenty years ago two different polymorphs of carbonic acid, α- and β-H2CO3, were isolated as thin, crystalline films. They were characterized by infrared and, of late, by Raman spectroscopy. Determination of the crystal structure of these two polymorphs, using cryopowder and thin film X-ray diffraction techniques, has failed so far. Recently, we succeeded in sublimating α-H2CO3 and trapping the vapor phase in a noble gas matrix, which was analyzed by infrared spectroscopy. In the same way we have now investigated the β-polymorph. Unlike α-H2CO3, β-H2CO3 was regarded to decompose upon sublimation. Still, we have succeeded in isolation of undecomposed carbonic acid in the matrix and recondensation after removal of the matrix here. This possibility of sublimation and recondensation cycles of β-H2CO3 adds a new aspect to the chemistry of carbonic acid in astrophysical environments, especially because there is a direct way of β-H2CO3 formation in space, but none for α-H2CO3. Assignments of the FTIR spectra of the isolated molecules unambiguously reveal two different carbonic acid monomer conformers (C(2v) and C(s)). In contrast to the earlier study on α-H2CO3, we do not find evidence for centrosymmetric (C(2h)) carbonic acid dimers here. This suggests that two monomers are entropically favored at the sublimation temperature of 250 K for β-H2CO3, whereas they are not at the sublimation temperature of 210 K for α-H2CO3.

Genetic Association Study of KCNQ5 Polymorphisms with High Myopia.

PubMed

Liao, Xuan; Yap, Maurice K H; Leung, Kim Hung; Kao, Patrick Y P; Liu, Long Qian; Yip, Shea Ping

2017-01-01

Identification of genetic variations related to high myopia may advance our knowledge of the etiopathogenesis of refractive error. This study investigated the role of potassium channel gene (KCNQ5) polymorphisms in high myopia. We performed a case-control study of 1563 unrelated Han Chinese subjects (809 cases of high myopia and 754 emmetropic controls). Five tag single-nucleotide polymorphisms (SNPs) of KCNQ5 were genotyped, and association testing with high myopia was conducted using logistic regression analysis adjusted for sex and age to give P asym values, and multiple comparisons were corrected by permutation test to give P emp values. All five noncoding SNPs were associated with high myopia. The SNP rs7744813, previously shown to be associated with refractive error and myopia in two GWAS, showed an odds ratio of 0.75 (95% CI 0.63-0.90; P emp = 0.0058) for the minor allele. The top SNP rs9342979 showed an odds ratio of 0.75 (95% CI 0.64-0.89; P emp = 0.0045) for the minor allele. Both SNPs are located within enhancer histone marks and DNase-hypersensitive sites. Our data support the involvement of KCNQ5 gene polymorphisms in the genetic susceptibility to high myopia and further exploration of KCNQ5 as a risk factor for high myopia.

A pipeline for the systematic identification of non-redundant full-ORF cDNAs for polymorphic and evolutionary divergent genomes: Application to the ascidian Ciona intestinalis

DOE PAGES

Gilchrist, Michael J.; Sobral, Daniel; Khoueiry, Pierre; ...

2015-05-27

Genome-wide resources, such as collections of cDNA clones encoding for complete proteins (full-ORF clones), are crucial tools for studying the evolution of gene function and genetic interactions. Non-model organisms, in particular marine organisms, provide a rich source of functional diversity. Marine organism genomes are, however, frequently highly polymorphic and encode proteins that diverge significantly from those of well-annotated model genomes. The construction of full-ORF clone collections from non-model organisms is hindered by the difficulty of predicting accurately the N-terminal ends of proteins, and distinguishing recent paralogs from highly polymorphic alleles. We also report a computational strategy that overcomes these difficulties,more » and allows for accurate gene level clustering of transcript data followed by the automated identification of full-ORFs with correct 5'- and 3'-ends. It is robust to polymorphism, includes paralog calling and does not require evolutionary proximity to well annotated model organisms. Here, we developed this pipeline for the ascidian Ciona intestinalis, a highly polymorphic member of the divergent sister group of the vertebrates, emerging as a powerful model organism to study chordate gene function, Gene Regulatory Networks and molecular mechanisms underlying human pathologies. Furthermore, using this pipeline we have generated the first full-ORF collection for a highly polymorphic marine invertebrate. It contains 19,163 full-ORF cDNA clones covering 60% of Ciona coding genes, and full-ORF orthologs for approximately half of curated human disease-associated genes.« less

Negative-pressure polymorphs made by heterostructural alloying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siol, Sebastian; Holder, Aaron; Steffes, James

The ability of a material to adopt multiple structures, known as polymorphism, is a fascinating natural phenomenon. Various polymorphs with unusual properties are routinely synthesized by compression under positive pressure. However, changing a material's structure by applying tension under negative pressure is much more difficult. We show how negative-pressure polymorphs can be synthesized by mixing materials with different crystal structures - a general approach that should be applicable to many materials. Theoretical calculations suggest that it costs less energy to mix low-density structures than high-density structures, due to less competition for space between the atoms. Proof-of-concept experiments confirm that mixingmore » two different high-density forms of MnSe and MnTe stabilizes a Mn(Se,Te) alloy with a low-density wurtzite structure. This Mn(Se,Te) negative-pressure polymorph has 2x to 4x lower electron effective mass compared to MnSe and MnTe parent compounds and has a piezoelectric response that none of the parent compounds have. Lastly, this example shows how heterostructural alloying can lead to negative-pressure polymorphs with useful properties - materials that are otherwise nearly impossible to make.« less

Negative-pressure polymorphs made by heterostructural alloying

DOE PAGES

Siol, Sebastian; Holder, Aaron; Steffes, James; ...

2018-04-20

The ability of a material to adopt multiple structures, known as polymorphism, is a fascinating natural phenomenon. Various polymorphs with unusual properties are routinely synthesized by compression under positive pressure. However, changing a material's structure by applying tension under negative pressure is much more difficult. We show how negative-pressure polymorphs can be synthesized by mixing materials with different crystal structures - a general approach that should be applicable to many materials. Theoretical calculations suggest that it costs less energy to mix low-density structures than high-density structures, due to less competition for space between the atoms. Proof-of-concept experiments confirm that mixingmore » two different high-density forms of MnSe and MnTe stabilizes a Mn(Se,Te) alloy with a low-density wurtzite structure. This Mn(Se,Te) negative-pressure polymorph has 2x to 4x lower electron effective mass compared to MnSe and MnTe parent compounds and has a piezoelectric response that none of the parent compounds have. Lastly, this example shows how heterostructural alloying can lead to negative-pressure polymorphs with useful properties - materials that are otherwise nearly impossible to make.« less

Recalibration of the sphalerite cosmobarometer: Experimental and theoretical treatment

NASA Astrophysics Data System (ADS)

Balabin, Alexey I.; Urusov, Vadim S.

1995-04-01

Temperature dependence of the composition of sphalerite in equilibrium with troilite + metallic iron has been determined experimentally from 400 to 840°C at 1 bar. The high-temperature runs (660-840°C) were conducted in evacuated silica tubes; a new version of the recrystallization in anhydrous halide flux technique was used for attaining equilibrium at 600-400°C. The zero-pressure solvus of sphalerite proved to be at higher FeS contents than was located by Barton and Toulmin (1966). Detailed calculations, based on updated thermochemical appraisal of the sphalerite (Zn,Fe)S solution, have shown the new solvus to be in apparent consistency with the high-pressure experimental data of Hutchison and Scott (1983 ). An improved calibration of the cosmobarometer is presented, based on our experimental results and those of Hutchison and Scott (1983) ; the calibration takes into account some inferences regarding thermodynamic properties of sphalerite solution and low-temperature polymorphism in FeS. Recently published metallographic cooling rates of iron meteorites (Saikumar and Goldstein, 1988) provide estimates of blocking temperatures for Fe diffusion in sphalerite, which fall in the range 205-217°C. Pressures of formation of these meteorites calculated from available sphalerite compositions range from 0 for Landes to 1.8 kbar for Toluca. The most reliable of the pressure estimates exhibit a linear relationship with wt% Ni of the meteorite.

Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na{sub 3}OBr and Na{sub 4}OI{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yonggang, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu; Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou, Henan 450006; High Pressure Synergetic Consortium

2016-01-14

The structure stability under high pressure and thermal expansion behavior of Na{sub 3}OBr and Na{sub 4}OI{sub 2}, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na{sub 3}OBr and Na{sub 4}OI{sub 2}, respectively. The cubic Na{sub 3}OBr structure and tetragonal Na{sub 4}OI{sub 2} with intergrowth K{sub 2}NiF{sub 4} structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na{sub 4}OI{sub 2} exhibits nearly isotropic compressibility. Negative thermal expansion was observed at lowmore » temperature range (20–80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.« less

Association between TLR2 and TLR4 Gene Polymorphisms and the Susceptibility to Inflammatory Bowel Disease: A Meta-Analysis.

PubMed

Cheng, Yang; Zhu, Yun; Huang, Xiuping; Zhang, Wei; Han, Zelong; Liu, Side

2015-01-01

The associations between toll-like receptor 2 (TLR2) and toll-like receptor 4(TLR4) polymorphisms and inflammatory bowel disease (IBD) susceptibility remain controversial. A meta-analysis was performed to assess these associations. A systematic search was performed to identify all relevant studies relating TLR2 and TLR4 polymorphisms and IBD susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed by ethnicity and publication quality. Thirty-eight eligible studies, assessing 10970 cases and 7061 controls were included. No TLR2 Arg677Trp polymorphism was found. No significant association was observed between TLR2 Arg753Gln polymorphism and Crohn's disease (CD) or ulcerative colitis (UC) in all genetic models. Interestingly, TLR4 Asp299Gly polymorphism was significantly associated with increased risk of CD and UC in all genetic models, except for the additive one in CD. In addition, a statistically significant association between TLR4 Asp299Gly polymorphism and IBD was observed among high quality studies evaluating Caucasians, but not Asians. Associations between TLR4 Thr399Ile polymorphisms and CD risk were found only in the allele and dominant models. The TLR4 Thr399Ile polymorphism was associated with UC risk in pooled results as well as subgroup analysis of high quality publications assessing Caucasians, in allele and dominant models. The meta-analysis provides evidence that TLR2 Arg753Gln is not associated with CD and UC susceptibility in Asians; TLR4 Asp299Gly is associated with CD and UC susceptibility in Caucasians, but not Asians. TLR4 Thr399Ile may be associated with IBD susceptibility in Caucasians only. Additional well-powered studies of Asp299Gly and other TLR4 variants are warranted.

Azathioprine-induced alopecia and leukopenia associated with NUDT15 polymorphisms.

PubMed

Nomura, H; Kurihara, Y; Saito, M; Fukushima, A; Shintani, Y; Shiiyama, R; Toshima, S; Kamata, A; Yamagami, J; Funakoshi, T; Kameyama, K; Amagai, M; Kubo, A; Umegaki-Arao, N

2018-04-28

Azathioprine (AZA), a widely used immunosuppressant, can induce cytotoxic effects including myelosuppression and alopecia. 1 Recent studies revealed that polymorphisms of NUDT15 are associated with thiopurine-induced alopecia and leukopenia. 2-5 The frequency of NUDT15 polymorphisms in East and South Asians is high (22.6% and 13.6%, respectively). 5 Thus, adverse event management during AZA treatment is essential for Asian populations with these polymorphisms. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Assessment of genetic diversity among Indian potato (Solanum tuberosum L.) collection using microsatellite and retrotransposon based marker systems.

PubMed

Sharma, Vishakha; Nandineni, Madhusudan R

2014-04-01

Potato (Solanum tuberosum) is an important non-cereal crop throughout the world and is highly recommended for ensuring global food security. Owing to the complexities in genetics and inheritance pattern of potato, the conventional method of cross breeding for developing improved varieties has been difficult. Identification and tagging of desirable traits with informative molecular markers would aid in the development of improved varieties. Insertional polymorphism of copia-like and gypsy-like long terminal repeat retrotransposons (RTN) were investigated among 47 potato varieties from India using Inter-Retrotransposon Amplified Polymorphism (IRAP) and Retrotransposon Microsatellite Amplified Polymorphism (REMAP) marker techniques and were compared with the DNA profiles obtained with simple sequence repeats (SSRs). The genetic polymorphism, efficiency of polymorphism and effectiveness of marker systems were evaluated to assess the extent of genetic diversity among Indian potato varieties. A total of 139 polymorphic SSR alleles, 270 IRAP and 98 REMAP polymorphic bands, showing polymorphism of 100%, 87.9% and 68.5%, respectively, were used for detailed characterization of the genetic relationships among potato varieties by using cluster analysis and principal coordinate analysis (PCoA). IRAP analysis resulted in the highest number of polymorphic bands with an average of 15 polymorphic bands per assay unit when compared to the other two marker systems. Based on pair-wise comparison, the genetic similarity was calculated using Dice similarity coefficient. The SSRs showed a wide range in genetic similarity values (0.485-0.971) as compared to IRAP (0.69-0.911) and REMAP (0.713-0.947). A Mantel's matrix correspondence test showed a high positive correlation (r=0.6) between IRAP and REMAP, an intermediate value (r=0.58) for IRAP and SSR and the lowest value (r=0.17) for SSR and REMAP. Statistically significant cophenetic correlation coefficient values, of 0.961, 0.941 and 0.905 were observed for REMAP, IRAP and SSR, respectively. The widespread presence and distinct DNA profiles for copia-like and gypsy-like RTNs in the examined genotypes indicate that these elements are active in the genome and may have even contributed to the potato genome organization. Although the three marker systems were capable of distinguishing all the 47 varieties; high reproducibility, low cost and ease of DNA profiling data collection make IRAP and REMAP markers highly efficient whole-genome scanning molecular probes for population genetic studies. Information obtained from the present study regarding the genetic association and distinctiveness provides an useful guide for selection of germplasm for plant breeding and conservation efforts. Copyright © 2014. Published by Elsevier Inc.

Methylenetetrahydrofolate Reductase Gene Polymorphism (C677T) as a Risk Factor for Arterial Thrombosis in Georgian Patients.

PubMed

Garakanidze, Sopio; Costa, Elísio; Bronze-Rocha, Elsa; Santos-Silva, Alice; Nikolaishvili, Giorgi; Nakashidze, Irina; Kakauridze, Nona; Glonti, Salome; Khukhunaishvili, Rusudan; Koridze, Marina; Ahmad, Sarfraz

2018-01-01

Methylenetetrahydrofolate reductase ( MTHFR) gene polymorphism (C677T)] is a well-recognized genetic risk factor for venous thrombosis; however, its association with arterial thrombosis is still under debate. Herein, we evaluated the prevalence of MTHFR C677T polymorphism in Georgian patients in comparison with healthy individuals and its association with arterial thrombosis. We enrolled 214 participants: 101 with arterial thrombosis (71.3% males; mean age: 66.3 ± 12.1 years) and 113 controls (67.3% males; mean age: 56.6 ± 11.3 years). Genomic DNA was extracted from dry blood spot on Whatman filter paper. Polymerase chain reaction was performed to determine MTHFR C677T polymorphism. Frequency of C677T allele polymorphism in controls was 21.2%, which corresponded to heterozygous and homozygous stage frequencies of 35.4% and 3.5%, respectively. In patient group, an allelic frequency of 33.2% was found, which corresponded to the presence of 48.5% of heterozygous and 8.9% of homozygous individuals. Comparing the frequency of mutated alleles between the 2 groups, a significantly high frequency of mutated alleles was found in patient group ( P < .05). In conclusion, high frequency of MTHFR C677T polymorphism found in arterial thrombosis patient group suggests that this polymorphism might increase the risk of arterial thrombosis in Georgian patients.

Phase relation of CaSO4 at high pressure and temperature up to 90 GPa and 2300 K

NASA Astrophysics Data System (ADS)

Fujii, Taku; Ohfuji, Hiroaki; Inoue, Toru

2016-05-01

Calcium sulfate (CaSO4), one of the major sulfate minerals in the Earth's crust, is expected to play a major role in sulfur recycling into the deep mantle. Here, we investigated the crystal structure and phase relation of CaSO4 up to ~90 GPa and 2300 K through a series of high-pressure experiments combined with in situ X-ray diffraction. CaSO4 forms three thermodynamically stable polymorphs: anhydrite (stable below 3 GPa), monazite-type phase (stable between 3 and ~13 GPa) and barite-type phase (stable up to at least 93 GPa). Anhydrite to monazite-type phase transition is induced by pressure even at room temperature, while monazite- to barite-type transition requires heating at least to 1500 K at ~20 GPa. The barite-type phase cannot always be quenched from high temperature and is distorted to metastable AgMnO4-type structure or another modified barite structure depending on pressure. We obtained the pressure-volume data and density of anhydrite, monazite- and barite-type phases and found that their densities are lower than those calculated from the PREM model in the studied P-T conditions. This suggests that CaSO4 is gravitationally unstable in the mantle and fluid/melt phase into which sulfur dissolves and/or sulfate-sulfide speciation may play a major role in the sulfur recycling into the deep Earth.

Mechanisms of high-temperature, solid-state flow in minerals and ceramics and their bearing on the creep behavior of the mantle

USGS Publications Warehouse

Kirby, S.H.; Raleigh, C.B.

1973-01-01

The problem of applying laboratory silicate-flow data to the mantle, where conditions can be vastly different, is approached through a critical review of high-temperature flow mechanisms in ceramics and their relation to empirical flow laws. The intimate association of solid-state diffusion and high-temperature creep in pure metals is found to apply to ceramics as well. It is shown that in ceramics of moderate grain size, compared on the basis of self-diffusivity and elastic modulus, normalized creep rates compare remarkably well. This comparison is paralleled by the near universal occurrence of similar creep-induced structures, and it is thought that the derived empirical flow laws can be associated with dislocation creep. Creep data in fine-grained ceramics, on the other hand, are found to compare poorly with theories involving the stress-directed diffusion of point defects and have not been successfully correlated by self-diffusion rates. We conclude that these fine-grained materials creep primarily by a quasi-viscous grain-boundary sliding mechanism which is unlikely to predominate in the earth's deep interior. Creep predictions for the mantle reveal that under most conditions the empirical dislocation creep behavior predominates over the mechanisms involving the stress-directed diffusion of point defects. The probable role of polymorphic transformations in the transition zone is also discussed. ?? 1973.

Isolation and cross-familial amplification of 41 microsatellites for the brook charr (Salvelinus fontinalis)

USGS Publications Warehouse

Perry, G.M.L.; King, T.L.; St. -Cyr, J.; Valcourt, M.; Bernatchez, L.

2005-01-01

The brook charr (Salvelinus fontinalis; Osteichthyes: Salmonidae) is a phenotypically diverse fish species inhabiting much of North America. But relatively few genetic diagnostic resources are available for this fish species. We isolated 41 microsatellites from S. fontinalis polymorphic in one or more species of salmonid fish. Thirty-seven were polymorphic in brook charr, 15 in the congener Arctic charr (Salvelinus alpinus) and 14 in the lake charr (Salvelinus namaycush). Polymorphism was also relatively high in Oncorhynchus, where 21 loci were polymorphic in rainbow trout (Oncorhynchus mykiss) and 16 in cutthroat trout (Oncorhynchus clarkii) but only seven and four microsatellite loci were polymorphic in the more distantly related lake whitefish (Coregonus clupeaformis) and Atlantic salmon (Salmo salar), respectively. One duplicated locus (Sfo228Lav) was polymorphic at both duplicates in S. fontinalis. ?? 2005 Blackwell Publishing Ltd.

Preferred temperature of juvenile Atlantic cod Gadus morhua with different haemoglobin genotypes at normoxia and moderate hypoxia.

PubMed

Petersen, Maria Faldborg; Steffensen, John Fleng

2003-01-01

Atlantic cod Gadus morhua has polymorphic haemoglobin, which can be separated into two homozygous types, HbI-1 and HbI-2, and one heterozygous type HbI-1/2. The geographical distribution of Atlantic cod with the different haemoglobin types varies, with the HbI(2) allele occurring at high frequency in northern regions, and the HbI(1) allele dominant in warmer areas. To determine if temperature is a selective parameter in the distribution of the haemoglobin types, the preferred temperature of the homozygous genotypes HbI-1 and HbI-2 was measured. We found that HbI-2 cod preferred a temperature of 8.2+/-1.5 degrees C while HbI-1 cod preferred 15.4+/-1.1 degrees C, and this preference was significant. The effect of hypoxia (35% oxygen saturation) on the preferred temperature was also measured. Previous studies showed that the preferred temperature of fish decreases during hypoxia, and this was the case for HbI-1 cod, which preferred 9.8+/-1.8 degrees C during hypoxia, whereas HbI-2 cod did not show this effect. The results indicate that environmental temperature changes will lead to a distributional change in the different haemoglobin types of Atlantic cod, global warming providing an advantage for HbI-1 cod. However, since HbI-1 cod prefer a low temperature under hypoxic conditions, a combination of increased water temperature and hypoxia could be unfavourable for Atlantic cod stocks.

T85C polymorphisms of the dihydropyrimidine dehydrogenase gene detected in gastric cancer tissues by high-resolution melting curve analysis.

PubMed

Fang, Weijia; Xu, Nong; Jin, Dazhi; Chen, Yu; Chen, Xiaogang; Zheng, Yi; Shen, Hong; Yuan, Ying; Zheng, Shusen

2012-01-01

Dihydropyrimidine dehydrogenase is a key enzyme acting on the metabolic pathway of medications for gastric cancer. High-resolution melting curve technology, which was developed recently, can distinguish the wild-type dihydropyrimidine dehydrogenase gene from multiple polymorphisms by fluorescent quantitative polymerase chain reaction products in a direct and effective manner. T85C polymorphisms of dihydropyrimidine dehydrogenase in the peripheral blood of 112 Chinese gastric cancer patients were detected by real-time polymerase chain reaction combined with high-resolution melting curve technology. Primer design, along with the reaction system and conditions, was optimized based on the GenBank sequence. Seventy nine cases of wild-type (TT, [70.5%]), 29 cases of heterozygous (TC, [25.9%]), and 4 cases of homozygous mutant (CC, [3.6%]) were observed. The result was completely consistent with the results of the sequencing. Real-time polymerase chain reaction combined with high-resolution melting curve technology is a rapid, simple, reliable, direct-viewing, and convenient method for the detection and screening of polymorphisms.

[Prevalence of dyslipidemia in middle-aged adults with NOS3 gene polymorphism and low cardiorespiratory fitness].

PubMed

Malagrino, Pamella A; Sponton, Carlos H G; Esposti, Rodrigo D; Franco-Penteado, Carla F; Fernandes, Romulo A; Bezerra, Marcos André C; Albuquerque, Dulcinéia M; Rodovalho, Cynara M; Bacci, Maurício; Zanesco, Angelina

2013-02-01

To evaluate the influence of the interaction between endothelial nitric oxide synthase gene (NOS3) polymorphisms at positions -786T>C, Glu298Asp and intron 4b/a, and cardiorespiratory fitness on plasma nitrite/nitrate levels, blood pressure, lipid profile, and prevalence of cardiometabolic disorders. Ninety-two volunteers were genotyped for NOS3 polymorphisms at positions (-786T>C and Glu298Asp) and (intron 4b/a) and divided according to the genotype: non-polymorphic (NP) and polymorphic (P). After that, they were subdivided according to the cardiorespiratory fitness associated with genotype: high (HNP and HP) and low (LNP and LP). The subjects with polymorphism for the interactions at positions Glu298Asp + intron 4b/a, and Glu298Asp+-786T>C showed the highest values in total cholesterol, as well as dyslipidemia. Our findings show that NOS3 gene polymorphisms at positions -786T>C, Glu298Asp, and intron 4b/a exert negative effects on the lipid profile compared with those who do not carry polymorphisms.

DRD2/ANKK1 gene polymorphisms in forensic autopsies of methamphetamine intoxication fatalities.

PubMed

Matsusue, Aya; Ishikawa, Takaki; Ikeda, Tomoya; Tani, Naoto; Arima, Hisatomi; Waters, Brian; Hara, Kenji; Kashiwagi, Masayuki; Takayama, Mio; Ikematsu, Natsuki; Kubo, Shin-Ichi

2018-04-22

Dopamine D2 receptor/ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1) gene polymorphisms have been associated with responses to psychotropic drugs and addiction. We analyzed two DRD2/ANKK1 polymorphisms, Taq1A and -141C Ins/Del, in 37 fatal methamphetamine (MA) intoxication cases and 235 control cases in which MA and psychotropic drugs were not detected. The association among polymorphism, cause of death, and cerebrospinal fluid (CSF) dopamine concentration was evaluated. The Taq1A polymorphism distribution in the fatal MA intoxication cases differed from in the controls (P = 0.030) with a significantly high A1/A1 + A1/A2 genotype frequency. No significant associations were observed between -141C Ins/Del polymorphisms and MA intoxication cases or between DRD2/ANKK1 polymorphisms and CSF dopamine concentrations. Our findings suggest that the DRD2/ANKK1 Taq1A polymorphism is associated with susceptibility to fatal MA intoxication. Copyright © 2018 Elsevier B.V. All rights reserved.

No evidence of association between NOD2/CARD15 gene polymorphism and atherosclerotic events after renal transplantation

PubMed Central

Courivaud, Cécile; Ferrand, Christophe; Deschamps, Marina; Tiberghien, Pierre; Chalopin, Jean-Marc; Duperrier, Anne; Saas, Philippe; Ducloux, Didier

2006-01-01

Stable renal transplant recipients (RTR) display high rates of atherosclerotic events (AE). Innate immunity and especially vascular inflammation play a role in the pathogenesis of atherosclerosis. It is illustrated both by an increased occurrence of post-renal transplant cardiovascular events in patients with elevated levels of C-reactive protein and by a correlation between post-transplant AE and Toll-like receptor-4 Asp299Gly polymorphism. Here, we analyze the influence NOD2/CARD15 gene polymorphism since NOD2 can modulate macrophage pro-inflammatory activity and macrophage is present in early atherosclerotic lesions. The incidence of single nucleotide polymorphism (SNP) in the three major polymorphic region of NOD2 gene (SNP8, SNP12 and SNP13) was assessed in 182 RTR and the correlation between such polymorphism and the development of AE was analyzed. No correlation was observed between NOD2 gene polymorphism and the occurrence of AE after renal transplantation. NOD2 gene polymorphism thus does not appear to influence cardiovascular complications in RTR. PMID:16641610

RSCA genotyping of MHC for high-throughput evolutionary studies in the model organism three-spined stickleback Gasterosteus aculeatus

PubMed Central

Lenz, Tobias L; Eizaguirre, Christophe; Becker, Sven; Reusch, Thorsten BH

2009-01-01

Background In all jawed vertebrates, highly polymorphic genes of the major histocompatibility complex (MHC) encode antigen presenting molecules that play a key role in the adaptive immune response. Their polymorphism is composed of multiple copies of recently duplicated genes, each possessing many alleles within populations, as well as high nucleotide divergence between alleles of the same species. Experimental evidence is accumulating that MHC polymorphism is a result of balancing selection by parasites and pathogens. In order to describe MHC diversity and analyse the underlying mechanisms that maintain it, a reliable genotyping technique is required that is suitable for such highly variable genes. Results We present a genotyping protocol that uses Reference Strand-mediated Conformation Analysis (RSCA), optimised for recently duplicated MHC class IIB genes that are typical for many fish and bird species, including the three-spined stickleback, Gasterosteus aculeatus. In addition we use a comprehensive plasmid library of MHC class IIB alleles to determine the nucleotide sequence of alleles represented by RSCA allele peaks. Verification of the RSCA typing by cloning and sequencing demonstrates high congruency between both methods and provides new insight into the polymorphism of classical stickleback MHC genes. Analysis of the plasmid library additionally reveals the high resolution and reproducibility of the RSCA technique. Conclusion This new RSCA genotyping protocol offers a fast, but sensitive and reliable way to determine the MHC allele repertoire of three-spined sticklebacks. It therefore provides a valuable tool to employ this highly polymorphic and adaptive marker in future high-throughput studies of host-parasite co-evolution and ecological speciation in this emerging model organism. PMID:19291291

Intracapsular development and dispersal polymorphism in the predatory gastropod Ocenebra erinaceus (Linnaeus 1758)

NASA Astrophysics Data System (ADS)

Smith, Kathryn E.; Reed, Adam J.; Thatje, Sven

2015-09-01

Intraspecific polymorphism during development, such as poecilogony or dispersal polymorphism, has rarely been observed in the marine environment. The ecological advantages of this bet-hedging strategy, whereby the offspring from one species exhibit multiple developmental modes, include the potential for rapid colonization of new habitats while simultaneously achieving a degree of gene flow between populations. The muricid gastropod, Ocenebra erinaceus, is a common, shallow-water marine predator found across England and France. Historically, O. erinaceus caused significant damage to shellfisheries, but more recently it has been impacted by TBT-induced imposex. Despite the previous attention given to this species, little is known about its encapsulated development. Studying O. erinaceus egg capsules from the Solent, UK, we describe intracapsular development at 15 °C, the in situ temperature at time of oviposition. Within each capsule, all embryos developed; no nurse eggs were present. Development was categorized into eight ontogenetic stages, although not all individuals displayed every stage; embryos hatched as either swimming late-pediveliger larvae or crawling juveniles after 59-69 days, indicating dispersal polymorphism to occur in this species. Swimming late-pediveliger larvae completed metamorphosis within 72 h of hatching. As O. erinaceus continues to recover from TBT pollution, dispersal polymorphism may facilitate a rapid expansion in both population size and range. If this occurs, O. erinaceus has the potential to, once again, become a serious problem for shellfisheries around Europe.

Low-Ca pyroxenes from LL group chondritic meteorites: Crystal structural studies and implications for their thermal histories

NASA Astrophysics Data System (ADS)

Artioli, G.; Davoli, G.

1994-12-01

Crystal structural refinements of one orthorhombic (Pbca) and two monoclinic (P21/c) single crystals, from chondrules of low-Ca pyroxenes from unequilibrated chondritic meteorites of the LL group, were carried out. The intracrystalline Fe-Mg distribution between the M1 and M2 crystallographic sites of the Parnallee (LL-3) orthoenstatite is suggestive of very rapid cooling, whereas both the structural state and intracrystalline Fe-Mg distribution in the Soko Banja (LL-4) and Jolomba (LL-6) clinoenstaties indicate rapid cooling from the high temperature polymorphs, with no significant re-equilibration at lower temperatures. These results imply that thermal metamorphism in the parent body, if present, was insufficient to allow re-equilibration of the pyroxene minerals to low temperature, ordered crystal structures. The data also indicate that, assuming low or mild pressure and shock effects, there is no well defined correlation between equilibrium temperature of the mineral phases and the alleged petrologic type of the meteorites. This evidence is consistent with a rubble pile model for the parent body accretional history, or with an onion shell model with very low thermal peak metamorphism, as is assumed for a very small object.

Temperatures of shock-induced shear instabilities and their relationship to fusion curves. [emission from glass

NASA Technical Reports Server (NTRS)

Schmitt, D. R.; Ahrens, T. J.

1983-01-01

New emission spectra for MgO and CaAl2Si2O8 (glass) are observed from 430 to 820 nm. Taken with previous data, it is suggested that transparent solids display three regimes of light emission upon shock compression to successively higher pressures: (1) characteristic radiation such as observed in MgO and previously in other minerals, (2) heterogeneous hot spot (greybody) radiation observed in CaAl2Si2O8 and previously in all transparent solids undergoing shock-induced phase transformations, and (3) blackbody emission observed in the high pressure phase regime in NaCl, SiO2, CaO, CaAl2Si2O8, and Mg2SiO4. The onset of the second regime may delineate the onset of shock-induced polymorphism whereas the onset of the third regime delineates the Hugoniot pressure required to achieve local thermal equilibrium in the shocked solid. It is also proposed that the hot spot temperatures and corresponding shock pressures determined in the second regime delineate points on the fusion curves of the high pressure phase.

Association between angiotensin II receptor gene polymorphism and serum angiotensin converting enzyme (SACE) activity in patients with sarcoidosis

PubMed Central

Takemoto, Y.; Sakatani, M.; Takami, S.; Tachibana, T.; Higaki, J.; Ogihara, T.; Miki, T.; Katsuya, T.; Tsuchiyama, T.; Yoshida, A.; Yu, H.; Tanio, Y.; Ueda, E.

1998-01-01

BACKGROUND—Serum angiotensin converting enzyme (SACE) is considered to reflect disease activity in sarcoidosis. SACE activity is increased in many patients with active sarcoid lesions. The mechanism for the increased SACE activity in this disease has not been clarified. ACE insertion/deletion (I/D) gene polymorphism has been reported to have an association with SACE levels in sarcoidosis, but no evidence of an association between angiotensin II receptor gene polymorphism and SACE in this disease has been found. A study of the association of angiotensin II receptor gene polymorphisms with sarcoidosis was therefore undertaken.
METHODS—ACE (I/D), angiotensin II type 1 receptor (AGTR1), and angiotensin II type 2 receptor (AGTR2 ) gene polymorphisms were investigated by polymerase chain reaction (PCR) and SACE levels were measured in three groups of patients: those with sarcoidosis or tuberculosis and normal controls.
RESULTS—There was no difference in allele frequency of AGTR1 and AGTR2 polymorphism among the three groups. Neither AGTR1 nor AGTR2 polymorphisms were associated with sarcoidosis. SACE activity was higher in patients with sarcoidosis with the AGTR1 A/C genotype than in others. However, this tendency was not detected in patients with tuberculosis.
CONCLUSIONS—The AGTR1 allele C is associated with high activity of SACE in patients with sarcoidosis. It is another predisposing factor for high levels of SACE in patients with sarcoidosis and is considered to be an independent factor from the ACE D allele for high levels of SACE in sarcoidosis. This fact could be one of the explanations for the increased SACE activity in sarcoidosis.

 PMID:9713444

Association of HMOX1 and NQO1 Polymorphisms with Metabolic Syndrome Components

PubMed Central

Martínez-Hernández, Angélica; Córdova, Emilio J.; Rosillo-Salazar, Oscar; García-Ortíz, Humberto; Contreras-Cubas, Cecilia; Islas-Andrade, Sergio; Revilla-Monsalve, Cristina; Salas-Labadía, Consuelo; Orozco, Lorena

2015-01-01

Metabolic syndrome (MetS) is among the most important public health problems worldwide, and is recognized as a major risk factor for various illnesses, including type 2 diabetes mellitus, obesity, and cardiovascular diseases. Recently, oxidative stress has been suggested as part of MetS aetiology. The heme oxygenase 1 (HMOX1) and NADH:quinone oxidoreductase 1 (NQO1) genes are crucial mediators of cellular defence against oxidative stress. In the present study, we analysed the associations of HMOX1 (GT)n and NQO1 C609T polymorphisms with MetS and its components. Our study population comprised 735 Mexican Mestizos unrelated volunteers recruited from different tertiary health institutions from Mexico City. In order to know the HMOX1 (GT)n and NQO1 C609T allele frequencies in Amerindians, we included a population of 241 Amerindian native speakers. Their clinical and demographic data were recorded. The HMOX1 (GT)n polymorphism was genotyped using PCR and fluorescence technology. NQO1 C609T polymorphism genotyping was performed using TaqMan probes. Short allele (<25 GT repeats) of the HMOX1 polymorphism was associated with high systolic and diastolic blood pressure, and the T allele of the NQO1 C609T polymorphism was associated with increased triglyceride levels and decreased HDL-c levels, but only in individuals with MetS. This is the first study to analyse the association between MetS and genes involved in oxidative stress among Mexican Mestizos. Our data suggest that polymorphisms of HMOX1 and NQO1 genes are associated with a high risk of metabolic disorders, including high systolic and diastolic blood pressure, hypertriglyceridemia, and low HDL-c levels in Mexican Mestizo individuals. PMID:25933176

Association of HMOX1 and NQO1 Polymorphisms with Metabolic Syndrome Components.

PubMed

Martínez-Hernández, Angélica; Córdova, Emilio J; Rosillo-Salazar, Oscar; García-Ortíz, Humberto; Contreras-Cubas, Cecilia; Islas-Andrade, Sergio; Revilla-Monsalve, Cristina; Salas-Labadía, Consuelo; Orozco, Lorena

2015-01-01

Metabolic syndrome (MetS) is among the most important public health problems worldwide, and is recognized as a major risk factor for various illnesses, including type 2 diabetes mellitus, obesity, and cardiovascular diseases. Recently, oxidative stress has been suggested as part of MetS aetiology. The heme oxygenase 1 (HMOX1) and NADH:quinone oxidoreductase 1 (NQO1) genes are crucial mediators of cellular defence against oxidative stress. In the present study, we analysed the associations of HMOX1 (GT)n and NQO1 C609T polymorphisms with MetS and its components. Our study population comprised 735 Mexican Mestizos unrelated volunteers recruited from different tertiary health institutions from Mexico City. In order to know the HMOX1 (GT)n and NQO1 C609T allele frequencies in Amerindians, we included a population of 241 Amerindian native speakers. Their clinical and demographic data were recorded. The HMOX1 (GT)n polymorphism was genotyped using PCR and fluorescence technology. NQO1 C609T polymorphism genotyping was performed using TaqMan probes. Short allele (<25 GT repeats) of the HMOX1 polymorphism was associated with high systolic and diastolic blood pressure, and the T allele of the NQO1 C609T polymorphism was associated with increased triglyceride levels and decreased HDL-c levels, but only in individuals with MetS. This is the first study to analyse the association between MetS and genes involved in oxidative stress among Mexican Mestizos. Our data suggest that polymorphisms of HMOX1 and NQO1 genes are associated with a high risk of metabolic disorders, including high systolic and diastolic blood pressure, hypertriglyceridemia, and low HDL-c levels in Mexican Mestizo individuals.

Multifunctional Logic Gate Controlled by Temperature

NASA Technical Reports Server (NTRS)

Stoica, Adrian; Zebulum, Ricardo

2005-01-01

A complementary metal oxide/semiconductor (CMOS) electronic circuit has been designed to function as a NAND gate at a temperature between 0 and 80 deg C and as a NOR gate at temperatures from 120 to 200 C. In the intermediate temperature range of 80 to 120 C, this circuit is expected to perform a function intermediate between NAND and NOR with degraded noise margin. The process of designing the circuit and the planned fabrication and testing of the circuit are parts of demonstration of polymorphic electronics a technological discipline that emphasizes designing the same circuit to perform different analog and/or digital functions under different conditions. In this case, the different conditions are different temperatures.

Bridging ImmunoGenomic Data Analysis Workflow Gaps (BIGDAWG): An integrated case-control analysis pipeline.

PubMed

Pappas, Derek J; Marin, Wesley; Hollenbach, Jill A; Mack, Steven J

2016-03-01

Bridging ImmunoGenomic Data-Analysis Workflow Gaps (BIGDAWG) is an integrated data-analysis pipeline designed for the standardized analysis of highly-polymorphic genetic data, specifically for the HLA and KIR genetic systems. Most modern genetic analysis programs are designed for the analysis of single nucleotide polymorphisms, but the highly polymorphic nature of HLA and KIR data require specialized methods of data analysis. BIGDAWG performs case-control data analyses of highly polymorphic genotype data characteristic of the HLA and KIR loci. BIGDAWG performs tests for Hardy-Weinberg equilibrium, calculates allele frequencies and bins low-frequency alleles for k×2 and 2×2 chi-squared tests, and calculates odds ratios, confidence intervals and p-values for each allele. When multi-locus genotype data are available, BIGDAWG estimates user-specified haplotypes and performs the same binning and statistical calculations for each haplotype. For the HLA loci, BIGDAWG performs the same analyses at the individual amino-acid level. Finally, BIGDAWG generates figures and tables for each of these comparisons. BIGDAWG obviates the error-prone reformatting needed to traffic data between multiple programs, and streamlines and standardizes the data-analysis process for case-control studies of highly polymorphic data. BIGDAWG has been implemented as the bigdawg R package and as a free web application at bigdawg.immunogenomics.org. Copyright © 2015 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilchrist, Michael J.; Sobral, Daniel; Khoueiry, Pierre

Genome-wide resources, such as collections of cDNA clones encoding for complete proteins (full-ORF clones), are crucial tools for studying the evolution of gene function and genetic interactions. Non-model organisms, in particular marine organisms, provide a rich source of functional diversity. Marine organism genomes are, however, frequently highly polymorphic and encode proteins that diverge significantly from those of well-annotated model genomes. The construction of full-ORF clone collections from non-model organisms is hindered by the difficulty of predicting accurately the N-terminal ends of proteins, and distinguishing recent paralogs from highly polymorphic alleles. We also report a computational strategy that overcomes these difficulties,more » and allows for accurate gene level clustering of transcript data followed by the automated identification of full-ORFs with correct 5'- and 3'-ends. It is robust to polymorphism, includes paralog calling and does not require evolutionary proximity to well annotated model organisms. Here, we developed this pipeline for the ascidian Ciona intestinalis, a highly polymorphic member of the divergent sister group of the vertebrates, emerging as a powerful model organism to study chordate gene function, Gene Regulatory Networks and molecular mechanisms underlying human pathologies. Furthermore, using this pipeline we have generated the first full-ORF collection for a highly polymorphic marine invertebrate. It contains 19,163 full-ORF cDNA clones covering 60% of Ciona coding genes, and full-ORF orthologs for approximately half of curated human disease-associated genes.« less

The 3R polymorph of CaSi{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nedumkandathil, Reji; Benson, Daryn E.; Grins, Jekabs

The Zintl phase CaSi{sub 2} commonly occurs in the 6R structure where puckered hexagon layers of Si atoms are stacked in an AA′BB′CC′ fashion. In this study we show that sintering of CaSi{sub 2} in a hydrogen atmosphere (30 bar) at temperatures between 200 and 700 °C transforms 6R-CaSi{sub 2} quantitatively into 3R-CaSi{sub 2}. In the 3R polymorph (space group R-3m (no. 166), a=3.8284(1), c=15.8966(4), Z=3) puckered hexagon layers are stacked in an ABC fashion. The volume per formula unit is about 3% larger compared to 6R-CaSi{sub 2}. First principles density functional calculations reveal that 6R and 3R-CaSi{sub 2} aremore » energetically degenerate at zero Kelvin. With increasing temperature 6R-CaSi{sub 2} stabilizes over 3R because of its higher entropy. This suggests that 3R-CaSi{sub 2} should revert to 6R at elevated temperatures, which however is not observed up to 800 °C. 3R-CaSi{sub 2} may be stabilized by small amounts of incorporated hydrogen and/or defects. - Graphical abstract: The common 6R form of CaSi{sub 2} can be transformed quantitatively into 3R-CaSi{sub 2} upon sintering in a hydrogen atmosphere. - Highlights: • Quantitative and reproducible bulk synthesis of the rare 3R polymorph of CaSi{sub 2}. • Clarification of the energetic relation between 3R and conventional 6R form. • 3R-CaSi{sub 2} is presumably stabilized by small amounts of incorporated hydrogen and/or defects.« less

Behavioral and physiological polymorphism in males of the austral lizard Liolaemus sarmientoi.

PubMed

Fernández, Jimena B; Bastiaans, Elizabeth; Medina, Marlin; Méndez De la Cruz, Fausto R; Sinervo, Barry R; Ibargüengoytía, Nora R

2018-02-01

Integrative behavioral studies show that the interplay between individual physiology and social behavior influences the ecology of the species, ultimately affecting individual fitness. Particularly in lizards, color polymorphism is associated with differential behaviors and reproductive strategies, which are evident in mature males during the mating season. Dominant males generally have greater endurance, higher body temperature, and larger bodies than submissive males, so they can acquire and defend larger territories and have greater access to females for mating. We studied whether the color morphs observed in males of one of the world's southernmost reptiles, Liolaemus sarmientoi, are related to behavioral variation during agonistic interactions, thermal physiology, morphology, and/or locomotor stamina. Liolaemus sarmientoi males exhibit three color morphs: red (RR), red-yellow (RY), and yellow (YY). These lizards exhibit subtle behavioral displays and we did not observe stamina differences among morphs. However, we found that RR males are more aggressive than YY males during agonistic encounters. In addition, greater body temperature change during trials, higher field body temperatures, and greater head sizes of RR males compared to RY or YY indicate that RR is a dominant morph, which may influence their ability to acquire and defend territory and tactics for achieving reproductive success.

An NQR Study of TNT Characteristics.

DTIC Science & Technology

1977-09-01

RDX , HMX , a r d some of t he heavy me t al 3~~: id~.s h~~’n for rn.nn ye.~rs been use d as rn~~lit~~ry nii p lns i n’t-~~~~, Thr p h y s i c a l...ambient temperatures of more than one coexisting crystal phase. This polymorphism is known to occur in TNT , HMX and PbN3, and is responsible for a...specific problems of TNT polymorphism and phase transitions were researched . This is one of the problems which is relevant to present day concerns . The

Association between ADAM metallopeptidase domain 33 gene polymorphism and risk of childhood asthma: a meta-analysis.

PubMed

Sun, F J; Zou, L Y; Tong, D M; Lu, X Y; Li, J; Deng, C B

2017-08-31

This study aimed to investigate the association between ADAM metallopeptidase domain 33 (ADAM33) gene polymorphisms and the risk of childhood asthma. The relevant studies about the relationship between ADAM33 gene polymorphisms and childhood asthma were searched from electronic databases and the deadline of retrieval was May 2016. The single nucleotide polymorphisms (SNPs) of ADAM33 (rs511898, rs2280092, rs3918396, rs528557, rs2853209, rs44707, rs2280091 and rs2280089) were analyzed based on several models including the allele, codominant, recessive and dominant models. The results showed that the ADAM33 rs2280091 polymorphism in all four genetic models was associated with an increased risk of childhood asthma. Positive associations were also found between the polymorphisms rs2280090, rs2787094, rs44707 and rs528557 and childhood asthma in some genetic models. This meta-analysis suggested that ADAM33 polymorphisms rs2280091, rs2280090, rs2787094, rs44707 and rs528557 were significantly associated with a high risk of childhood asthma.

Identification and characterization of microsatellite markers from the tropical sea cucumber, Stichopus horrens (Selenka).

PubMed

Shangguan, J B; Li, Z B; Yuan, Y; Huang, Y S

2015-10-28

Tropical commercial sea cucumber Stichopus horrens is extensively distributed throughout the tropical Indo-Pacific region, and wild stocks have been severely depleted over the past decade. In this study, we used the microsatellite enrichment library of S. horrens to identify and characterize 13 microsatellite loci, including 11 polymorphic loci and 2 monomorphic loci. Among the 11 polymorphic loci, the number of alleles was 3-8. The observed and expected heterozygosity varied from 0.1364 to 0.8966 and from 0.1653 to 0.7551, respectively. Additionally, all 11 polymorphic loci showed moderate and high polymorphism with the polymorphism information content (0.271-0.7311). A total of 9 polymorphic loci were in Hardy-Weinberg equilibrium, except for 2 loci (adjusted P = 0.004545). Linkage disequilibrium was not detected in any pairs of polymorphic loci. The present study will be useful for studying genetic structure, population conservation, and breeding of wild S. horrens; moreover, our results contribute to the phylogeny and evolutionary research of Holothuroidea.

Association between Six CETP Polymorphisms and Metabolic Syndrome in Uyghur Adults from Xinjiang, China

PubMed Central

Hou, Huixian; Ma, Rulin; Guo, Heng; He, Jia; Hu, Yunhua; Mu, Lati; Yan, Yizhong; Ma, Jiaolong; Li, Shugang; Zhang, Jingyu; Ding, Yusong; Zhang, Mei; Niu, Qiang; Liu, Jiaming; Guo, Shuxia

2017-01-01

Objective: To explore the association between CETP gene polymorphisms and metabolic syndrome (MS), as well as the relationship between the CETP gene polymorphisms and each component of MS. Methods: A total of 571 individuals which were randomly selected from 5692 Uyghur adults were subdivided into two groups, including 280 patients with MS and 291 control subjects, using the group-matching method after matching for gender. We detected CETP polymorphisms (rs5882, rs1800775, rs3764261, rs12149545, rs711752, and rs708272) by using the Snapshot method. Results: (1) Significant differences were found involving the frequency distribution of genotypes and alleles of rs1800775, rs3764261, rs12149545, rs711752, and rs708272 between the control and MS groups (all p < 0.05). (2) rs1800775, rs3764261, rs12149545, rs711752, and rs708272 polymorphisms were significantly related to the risk of MS (all p < 0.05). (3) The rs1800775 polymorphism was associated with high fasting blood glucose levels and low high density lipoprotein cholesterol (HDL-C); rs3764261 and rs12149545 polymorphisms were associated with all components of MS except high blood pressure; rs711752 and rs708272 polymorphisms were associated with low HDL-C (all p < 0.05). (4) Complete linkage disequilibrium (LD) was identified for two pairs of single nucleotide polymorphisms (SNPs) (rs3764261 and rs12149545 (D’ = 1.000, r2 = 0.931), rs711752 and rs708272 (D’ = 1.000, r2 = 0.996)). (5) The A-G-G-G-C (p = 0.013, odds ratio [OR] = 0.622, 95% confidence interval [95% CI] = 0.427–0.906) and A-T-A-A-T (p < 0.001, OR = 0.519, 95% CI = 0.386–0.697) haplotypes were more frequent in the control group than in the case group. Conclusions: The rs1800775, rs3764261, rs12149545, rs711752, and rs708272 polymorphisms of CETP were associated with MS and its components among the Uyghur ethnic group. Complete LD was found between two pairs of SNPs (rs3764261 and rs12149545, rs711752, and rs708272). The A-G-G-G-C and A-T-A-A-T haplotypes might be protective factors for MS. PMID:28629169

Thermally-prepared polymorphic forms of cilostazol.

PubMed

Stowell, Grayson W; Behme, Robert J; Denton, Stacy M; Pfeiffer, Inigo; Sancilio, Frederick D; Whittall, Linda B; Whittle, Robert R

2002-12-01

Prior to this study, cilostazol, an antithrombotic drug, was thought to exist as a single crystalline phase with a melting point of approximately 159 degrees C (Form A). On cooling, melts often form a glass that, when heated, may crystallize as additional crystalline polymorphic forms. Cilostazol, when reheated, subsequently forms polymorphs that melt at approximately 136 degrees C (Form B) and 146 degrees C (Form C). Free-energy temperature diagrams estimated from calorimetry data reveal that each pair of the cilostazol polymorphs (A-B, B-C, and A-C) is monotropic. Essentially pure samples of suitable crystalline shape and size permitted single crystal structural analysis of Forms A and C. Theoretical solubility ratios calculated using calorimetry data indicate that at 37 degrees C, Form B should be more than four times more soluble and Form C should be more than two times more soluble than Form A. Forms B and C could not be crystallized from solvents. Metastable forms from super cooled melts analyzed by intrinsic dissolution and Fourier transform-Raman experiments demonstrated that Forms B and C undergo a rapid, solvent-mediated recrystallization to Form A, making dissolution rate measurements difficult. Copyright 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:2481-2488, 2002

A Liquid-Liquid Transition in an Undercooled Ti-Zr-Ni Liquid

NASA Technical Reports Server (NTRS)

Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.

2003-01-01

If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, TI, finally freezing into a glass below a characteristic temperature called the glass transition temperature, T,. In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of HzO and Si4. Such phase transitions have been predicted in some stable liquids, i.e. above TI at atmospheric pressure, for Si02 and BeF;, but these have not been verified experimentally. They have been observed in liquids of P7, Sis and C9, but only under high pressure. All of these transitions are driven by an anomalous density change, i.e. change in local structure, with temperature or pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity liquid that is not driven by an anomalous density change, but by an approach to a constant configuration state. A maximum in the specific heat at constant pressure, similar to what is normally observed near T,, is reported here for undercooled low viscosity liquids of quasicrystal- forming Ti-Zr-Ni alloys. that includes cooperativity, by incorporating a temperature dependent excitation energy fits the data well, signaling a phase transition.

Structural and impurity phase transitions of LiNaSO4:RE probed using cathodo-thermoluminescence

NASA Astrophysics Data System (ADS)

Maghrabi, M.; Finch, A. A.; Townsend, P. D.

2008-11-01

Spectrally resolved cathodo-thermoluminescence spectra of rare earth (RE) doped LiNaSO4 measured from 20 to 673 K reveal several anomalies in the RE emission lines and intensities. The low (20-300 K) temperature data show a discontinuous change in intensity at ~170 K that is either a marked intensity enhancement or a drop truncating the entire spectrum. Such an effect on the host luminescence has previously been assigned to a transition between cubic and hexagonal polymorphs of ice nanoparticle inclusions. Similar, but less profound anomalies are seen above room temperature (300-673 K) where the changes take the form of either a discontinuity in intensity at ~480 K or reduced intensity in the range 430-530 K. There are changes in the relative intensities of different emission lines of the same dopant in this temperature range. Such high temperature variations are ascribed to structural phase changes within the LiNaSO4 crystals. The behaviours may result from Li-poor surfaces or twin boundaries behaving like Na2SO4. This phase change is suggested in the open literature for LiNaSO4 but not yet fully documented, perhaps because the effects span a wide range of temperatures or due to experimental features inherent in most luminescence facilities.

Temperature induced phase transition of CaMn{sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3} phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orlova, Maria, E-mail: maria.p.orlova@gmail.com; Perfler, Lukas; Tribus, Martina

2016-03-15

In this work we investigated the structural behaviour of a CaMn{sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3}. Due to the presence of divalent Mn{sup 2+} cations this compound can possess interesting luminescence properties. It was recently understood that this phosphate undergoes a temperature induced irreversible phase transition in the range of 800–875 °C. It has also been shown that the 3d–3d luminescence of Mn{sup 2+} increases 10 fold for the high temperature polymorph. To determine the Mn environment structural investigations of both phases have been performed by the X-ray powder diffraction and Raman spectroscopy methods. The low temperature modification adopts the trigonalmore » NZP structure type with a slightly lower symmetry (space group R32, a=8.7850(2) Å, c=22.6496(7) Å, V=1514.8(1) Å{sup 3}). The high temperature form in turn has orthorhombic symmetry (space group Pnma, a=6.2350(3) Å, b=6.6281(3) Å, c=14.4731(6) Å, V=598.13(5) Å{sup 3}). Both structures were solved ab-initio from powder data and structural analysis was performed. In-situ and RT Raman spectra are consistent with the XRD derived structural model. Mn{sup 2+} cations occupy different types of positions in these structures and a change in Mn coordination number (6 for LT phase, 7 for HT phase) results in different Mn–O bond lengths. These differences may explain the change in the optical properties between the polymorphs. - Graphical abstract: The compound CaMn{sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3} was synthesized in order to create a material with enhanced luminescent properties. The goal of present studies is to define Mn{sup 2+} environment and its changes due to the structural transformations of the phosphate along phase transition at the T range of 800–875 °C. It was found that LT modification adopts the trigonal NZP structure type, sp.gr. R32, the HT form in turn exhibits orthorhombic symmetry sp.gr. Pnma. Mn2+ cations occupy different types of positions in those structures and a change in coordination number of Mn (6 for LT phase, 7 for HT phase) results in a change in Mn–O bond lengths.« less

Temperature Dependence of the Structural Parameters in the Transformation of Aragonite to Calcite, as Determined from In Situ Synchrotron Powder X-ray-Diffratction Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antao, Sytle M.; Hassan, Ishmael; West Indies)

The temperature dependency of the crystal structure and the polymorphic transition of CaCO{sub 3} from aragonite to calcite were studied using Rietveld structure refinement and high-temperature in situ synchrotron powder X-ray-diffraction data at ambient pressure, P. The orthorhombic metastable aragonite at room P, space group Pmcn, transforms to trigonal calcite, space group R{bar 3}c, at about T{sub c} = 468 C. This transformation occurs rapidly; it starts at about 420 C and is completed by 500 C, an 80 C interval that took about 10 minutes using a heating rate of 8 C/min. Structurally, from aragonite to calcite, the distributionmore » of the Ca atom changes from approximately hexagonal to cubic close-packing. A 5.76% discontinuous increase in volume accompanies the reconstructive first-order transition. Besides the change in coordination of the Ca atom from nine to six from aragonite to calcite, the CO{sub 3} groups change by a 30{sup o} rotation across the transition.« less

Origin of high piezoelectric activity in ferroelectric (K0.44Na0.52Li0.04)-(Nb0.84Ta0.1Sb0.06)O3 ceramics

NASA Astrophysics Data System (ADS)

Akdoǧan, E. K.; Kerman, K.; Abazari, M.; Safari, A.

2008-03-01

We study the temperature dependence of dielectric constant (K) and spontaneous polarization (Ps) in the range of -95-200°C. Cubic (C)-tetragonal (T) and T-orthorhombic (O) transitions are observed at 264 and 25°C, respectively. The Curie-Weiss temperature of C-T transition is 249°C, indicating it is first order. X-ray data indicate T-O phase coexistence at 25°C. A singularity in Ps at 25°C and a T-O phase coexistence spanning 25-31°C was observed, wherein Ps increases from 17×10-2C /m2 at 31°Cto23×10-2C/m2 25°C. The transition at 25°C appears diffusionless and polymorphic with martensite start and finish temperatures of 31 and 25°C, respectively. The maximum in d33 is 345pC/N and is attributed to the instability at 25°C, where Ps and K show singularity.

Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

PubMed

Kang, Il-Mo; Roh, Ki-Min

2013-01-01

The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

Genetic Polymorphism Associated Prefrontal Glutathione and Its Coupling With Brain Glutamate and Peripheral Redox Status in Early Psychosis.

PubMed

Xin, Lijing; Mekle, Ralf; Fournier, Margot; Baumann, Philipp S; Ferrari, Carina; Alameda, Luis; Jenni, Raoul; Lu, Huanxiang; Schaller, Benoit; Cuenod, Michel; Conus, Philippe; Gruetter, Rolf; Do, Kim Q

2016-09-01

Oxidative stress and glutathione (GSH) metabolism dysregulation has been implicated in the pathophysiology of schizophrenia. GAG-trinucleotide repeat (TNR) polymorphisms in the glutamate-cysteine ligase catalytic gene (GCLC), the rate-limiting enzyme for GSH synthesis, are associated with schizophrenia. In addition, GSH may serve as a reserve pool for neuronal glutamate (Glu) through the γ-glutamyl cycle. The aim of this study is to investigate brain [GSH] and its association with GCLC polymorphism, peripheral redox indices and brain Glu. Magnetic resonance spectroscopy was used to measure [GSH] and [Glu] in the medial prefrontal cortex (mPFC) of 25 early-psychosis patients and 33 controls. GCLC polymorphism was genotyped, glutathione peroxidases (GPx) and glutathione reductase (GR) activities were determined in blood cells. Significantly lower [GSHmPFC] in GCLC high-risk genotype subjects were revealed as compared to low-risk genotype subjects independent of disease status. In male subjects, [GSHmPFC] and blood GPx activities correlate positively in controls (P = .021), but negatively in patients (P = .039). In GCLC low-risk genotypes, [GlumPFC] are lower in patients, while it is not the case for high-risk genotypes. GCLC high-risk genotypes are associated with low [GSHmPFC], highlighting that GCLC polymorphisms should be considered in pathology studies of cerebral GSH. Low brain GSH levels are related to low peripheral oxidation status in controls but with high oxidation status in patients, pointing to a dysregulated GSH homeostasis in early psychosis patients. GCLC polymorphisms and disease associated correlations between brain GSH and Glu levels may allow patients stratification. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Genetic polymorphisms in one-carbon metabolism: associations with CpG island methylator phenotype (CIMP) in colon cancer and the modifying effects of diet

PubMed Central

Curtin, Karen; Slattery, Martha L.; Ulrich, Cornelia M.; Bigler, Jeannette; Levin, Theodore R.; Wolff, Roger K.; Albertsen, Hans; Potter, John D.; Samowitz, Wade S.

2008-01-01

This study investigated associations between CpG island methylator phenotype (CIMP) colon cancer and genetic polymorphisms relevant to one-carbon metabolism and thus, potentially the provision of methyl groups and risk of colon cancer. Data from a large, population-based case–control study (916 incident colon cancer cases and 1972 matched controls) were used. Candidate polymorphisms in methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS), transcobalamin II (TCNII), methionine synthase (MTR), reduced folate carrier (RFC), methylene-tetrahydrofolate dehydrogenase 1 (MTHFD1), dihydrofolate reductase (DHFR) and alcohol dehydrogenase 3 (ADH3) were evaluated. CIMP− or CIMP+ phenotype was based on five CpG island markers: MINT1, MINT2, MINT31, p16 and MLH1. The influence of specific dietary factors (folate, methionine, vitamin B12 and alcohol) on these associations was also analyzed. We hypothesized that polymorphisms involved in the provision of methyl groups would be associated with CIMP+ tumors (two or more of five markers methylated), potentially modified by diet. Few associations specific to CIMP+ tumors were observed overall, which does not support the hypothesis that the provision of methyl groups is important in defining a methylator phenotype. However, our data suggest that genetic polymorphisms in MTHFR 1298A > C, interacting with diet, may be involved in the development of highly CpG-methylated colon cancers. AC and CC genotypes in conjunction with a high-risk dietary pattern (low folate and methionine intake and high alcohol use) were associated with CIMP+ (OR = 2.1, 95% CI = 1.3–3.4 versus AA/high risk; P-interaction = 0.03). These results provide only limited support for a role of polymorphisms in one-carbon metabolism in the etiology of CIMP colon cancer. PMID:17449906

Genetic polymorphisms in one-carbon metabolism: associations with CpG island methylator phenotype (CIMP) in colon cancer and the modifying effects of diet.

PubMed

Curtin, Karen; Slattery, Martha L; Ulrich, Cornelia M; Bigler, Jeannette; Levin, Theodore R; Wolff, Roger K; Albertsen, Hans; Potter, John D; Samowitz, Wade S

2007-08-01

This study investigated associations between CpG island methylator phenotype (CIMP) colon cancer and genetic polymorphisms relevant to one-carbon metabolism and thus, potentially the provision of methyl groups and risk of colon cancer. Data from a large, population-based case-control study (916 incident colon cancer cases and 1,972 matched controls) were used. Candidate polymorphisms in methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS), transcobalamin II (TCNII), methionine synthase (MTR), reduced folate carrier (RFC), methylenetetrahydrofolate dehydrogenase 1 (MTHFD1), dihydrofolate reductase (DHFR) and alcohol dehydrogenase 3 (ADH3) were evaluated. CIMP- or CIMP+ phenotype was based on five CpG island markers: MINT1, MINT2, MINT31, p16 and MLH1. The influence of specific dietary factors (folate, methionine, vitamin B(12) and alcohol) on these associations was also analyzed. We hypothesized that polymorphisms involved in the provision of methyl groups would be associated with CIMP+ tumors (two or more of five markers methylated), potentially modified by diet. Few associations specific to CIMP+ tumors were observed overall, which does not support the hypothesis that the provision of methyl groups is important in defining a methylator phenotype. However, our data suggest that genetic polymorphisms in MTHFR 1,298A > C, interacting with diet, may be involved in the development of highly CpG-methylated colon cancers. AC and CC genotypes in conjunction with a high-risk dietary pattern (low folate and methionine intake and high alcohol use) were associated with CIMP+ (OR = 2.1, 95% CI = 1.3-3.4 versus AA/high risk; P-interaction = 0.03). These results provide only limited support for a role of polymorphisms in one-carbon metabolism in the etiology of CIMP colon cancer.

Stability limits and transformation pathways of α-quartz under high pressure

NASA Astrophysics Data System (ADS)

Hu, Q. Y.; Shu, J.-F.; Yang, W. G.; Park, C.; Chen, M. W.; Fujita, T.; Mao, H.-K.; Sheng, H. W.

2017-03-01

Ubiquitous on Earth, α-quartz plays an important role in modern science and technology. However, despite extensive research in the past, the mechanism of the polymorphic transitions of α-quartz at high pressures remains poorly understood. Here, combining in situ single-crystal x-ray diffraction experiment and advanced ab initio modeling, we report two stability limits and competing transition pathways of α-quartz under high pressure. Under near-equilibrium compression conditions at room temperature, α-quartz transits to a new P 2 /c silica phase via a structural intermediate. If the thermally activated transition is kinetically suppressed, the ultimate stability of α-quartz is controlled by its phonon instability and α-quartz collapses into a different crystalline phase. Our studies reveal that pressure-induced solid-state transformation of α-quartz undergoes a succession of structural stability limits, due to thermodynamic and mechanical catastrophes, and exhibits a hierarchy of transition pathways contingent upon kinetic conditions.

Electron spin relaxation in two polymorphic structures of GaN

NASA Astrophysics Data System (ADS)

Kang, Nam Lyong

2015-03-01

The relaxation process of electron spin in systems of electrons interacting with piezoelectric deformation phonons that are mediated through spin-orbit interactions was interpreted from a microscopic point of view using the formula for the electron spin relaxation times derived by a projection-reduction method. The electron spin relaxation times in two polymorphic structures of GaN were calculated. The piezoelectric material constant for the wurtzite structure obtained by a comparison with a previously reported experimental result was {{P}pe}=1.5 × {{10}29} eV {{m}-1}. The temperature and magnetic field dependence of the relaxation times for both wurtzite and zinc-blende structures were similar, but the relaxation times in zinc-blende GaN were smaller and decreased more rapidly with increasing temperature and magnetic field than that in wurtzite GaN. This study also showed that the electron spin relaxation for wurtzite GaN at low density could be explained by the Elliot-Yafet process but not for zinc-blende GaN in the metallic regime.

Dynamically fluctuating electric dipole moments in fullerene-based magnets.

PubMed

Kambe, Takashi; Oshima, Kokichi

2014-09-19

We report here the direct evidence of the existence of a permanent electric dipole moment in both crystal phases of a fullerene-based magnet--the ferromagnetic α-phase and the antiferromagnetic α'-phase of tetra-kis-(dimethylamino)-ethylene-C60 (TDAE-C60)--as determined by dielectric measurements. We propose that the permanent electric dipole originates from the pairing of a TDAE molecule with surrounding C60 molecules. The two polymorphs exhibit clear differences in their dielectric responses at room temperature and during the freezing process with dynamically fluctuating electric dipole moments, although no difference in their room-temperature structures has been previously observed. This result implies that two polymorphs have different local environment around the molecules. In particular, the ferromagnetism of the α-phase is founded on the homogeneous molecule displacement and orientational ordering. The formation of the different phases with respect to the different rotational states in the Jahn-Teller distorted C60s is also discussed.

Dynamically fluctuating electric dipole moments in fullerene-based magnets

PubMed Central

Kambe, Takashi; Oshima, Kokichi

2014-01-01

We report here the direct evidence of the existence of a permanent electric dipole moment in both crystal phases of a fullerene-based magnet—the ferromagnetic α-phase and the antiferromagnetic α′-phase of tetra-kis-(dimethylamino)-ethylene-C60 (TDAE-C60)—as determined by dielectric measurements. We propose that the permanent electric dipole originates from the pairing of a TDAE molecule with surrounding C60 molecules. The two polymorphs exhibit clear differences in their dielectric responses at room temperature and during the freezing process with dynamically fluctuating electric dipole moments, although no difference in their room-temperature structures has been previously observed. This result implies that two polymorphs have different local environment around the molecules. In particular, the ferromagnetism of the α-phase is founded on the homogeneous molecule displacement and orientational ordering. The formation of the different phases with respect to the different rotational states in the Jahn–Teller distorted C60s is also discussed. PMID:25236361

Hydrothermal Synthesis of VO2 Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows.

PubMed

Li, Ming; Magdassi, Shlomo; Gao, Yanfeng; Long, Yi

2017-09-01

Vanadium dioxide (VO 2 ) is a widely studied inorganic phase change material, which has a reversible phase transition from semiconducting monoclinic to metallic rutile phase at a critical temperature of τ c ≈ 68 °C. The abrupt decrease of infrared transmittance in the metallic phase makes VO 2 a potential candidate for thermochromic energy efficient windows to cut down building energy consumption. However, there are three long-standing issues that hindered its application in energy efficient windows: high τ c , low luminous transmittance (T lum ), and undesirable solar modulation ability (ΔT sol ). Many approaches, including nano-thermochromism, porous films, biomimetic surface reconstruction, gridded structures, antireflective overcoatings, etc, have been proposed to tackle these issues. The first approach-nano-thermochromism-which is to integrate VO 2 nanoparticles in a transparent matrix, outperforms the rest; while the thermochromic performance is determined by particle size, stoichiometry, and crystallinity. A hydrothermal method is the most common method to fabricate high-quality VO 2 nanoparticles, and has its own advantages of large-scale synthesis and precise phase control of VO 2 . This Review focuses on hydrothermal synthesis, physical properties of VO 2 polymorphs, and their transformation to thermochromic VO 2 (M), and discusses the advantages, challenges, and prospects of VO 2 (M) in energy-efficient smart windows application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymorphisms in heterocyclic aromatic amines metabolism-related genes are associated with colorectal adenoma risk

PubMed Central

Eichholzer, Monika; Rohrmann, Sabine; Barbir, Aline; Hermann, Silke; Teucher, Birgit; Kaaks, Rudolf; Linseisen, Jakob

2012-01-01

Colorectal adenoma (CRA) and colorectal cancer (CRC) risks have been linked to the intake of red and processed meat. Heterocyclic aromatic amines (HCA) formed herein during high temperature cooking, are metabolized by a variety of enzymes, and allelic variation in the coding genes could influence individual CRA risk. Associations of polymorphisms in NAT1, NAT2, GSTA1, SULT1A1, CYP1A2, UGT1A7, UGT1A9, GSTP1 genes with colorectal adenoma risk were investigated in a nested case-control study of the EPIC-Heidelberg cohort including 428 cases matched by age, sex and year of recruitment with one or two controls (n=828) with negative colonoscopy per case. Genoyping was preformed with the Sequenom MassArray system and the LightCycler 480. Conditional logistic regression was used to compute odds ratios (OR) and corresponding 95% confidence intervals (CI). For rs15561 (NAT1) and rs1057126 (NAT1), the rarer allel was significantly inversely associated with adenoma risk OR=0.80 (95% CI 0.65-0.97) and (OR=0.81 (95% CI 0.65-0.99) and, respectively). For the combined NAT2 alleles encoding for enzymes with medium (versus slow) activity we also observed a significantly inverse association with adenoma risk (OR=0.75; 95% CI 0.85-0.97). In addition, homozygous carriers of the A allele of rs3957357 (GSTA1), i.e., those with a decreased enzyme activity, had a decreased risk of colorectal adenoma with an OR of 0.68 (95% CI 0.50-0.92; AA versus GG/GA). Polymorphisms in the other tested genes did not modify the risk of colorectal adenomas. In conclusion, polymorphisms in NAT1, NAT2, and GSTA1 are related to colorectal adenoma risk in this German cohort. PMID:22724046

Polymorphisms in heterocyclic aromatic amines metabolism-related genes are associated with colorectal adenoma risk.

PubMed

Eichholzer, Monika; Rohrmann, Sabine; Barbir, Aline; Hermann, Silke; Teucher, Birgit; Kaaks, Rudolf; Linseisen, Jakob

2012-01-01

Colorectal adenoma (CRA) and colorectal cancer (CRC) risks have been linked to the intake of red and processed meat. Heterocyclic aromatic amines (HCA) formed herein during high temperature cooking, are metabolized by a variety of enzymes, and allelic variation in the coding genes could influence individual CRA risk. Associations of polymorphisms in NAT1, NAT2, GSTA1, SULT1A1, CYP1A2, UGT1A7, UGT1A9, GSTP1 genes with colorectal adenoma risk were investigated in a nested case-control study of the EPIC-Heidelberg cohort including 428 cases matched by age, sex and year of recruitment with one or two controls (n=828) with negative colonoscopy per case. Genoyping was preformed with the Sequenom MassArray system and the LightCycler 480. Conditional logistic regression was used to compute odds ratios (OR) and corresponding 95% confidence intervals (CI). For rs15561 (NAT1) and rs1057126 (NAT1), the rarer allel was significantly inversely associated with adenoma risk OR=0.80 (95% CI 0.65-0.97) and (OR=0.81 (95% CI 0.65-0.99) and, respectively). For the combined NAT2 alleles encoding for enzymes with medium (versus slow) activity we also observed a significantly inverse association with adenoma risk (OR=0.75; 95% CI 0.85-0.97). In addition, homozygous carriers of the A allele of rs3957357 (GSTA1), i.e., those with a decreased enzyme activity, had a decreased risk of colorectal adenoma with an OR of 0.68 (95% CI 0.50-0.92; AA versus GG/GA). Polymorphisms in the other tested genes did not modify the risk of colorectal adenomas. In conclusion, polymorphisms in NAT1, NAT2, and GSTA1 are related to colorectal adenoma risk in this German cohort.

An integrated genetic linkage map of watermelon and genetic diversity based on single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers

USDA-ARS?s Scientific Manuscript database

Watermelon (Citrullus lanatus var. lanatus) is an important vegetable fruit throughout the world. A high number of single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers should provide large coverage of the watermelon genome and high phylogenetic resolution of germplasm acces...

Workshop Report: Fundamental Reactions in Solid Propellant Combustion

DTIC Science & Technology

1979-05-01

combustion conditions. 6. What effect might a pressure-induced phase transition to a polymorph other than 6- HMX have on the pressure slope break during...pure HMX as well. Nevertheless, it is recommended that the high pressure polymorphs of HMX and RDX be determined. It was also felt that there...plateau burning phenomena E. Solid phase, surface, gas phase reactions F. Phase transitions : melting, vaporization, polymorphs G. Flame

Comparative analyses of genetic/epigenetic diversities and structures in a wild barley species (Hordeum brevisubulatum) using MSAP, SSAP and AFLP.

PubMed

Shan, X H; Li, Y D; Liu, X M; Wu, Y; Zhang, M Z; Guo, W L; Liu, B; Yuan, Y P

2012-08-17

We analyzed genetic diversity and population genetic structure of four artificial populations of wild barley (Hordeum brevisubulatum); 96 plants collected from the Songnen Prairie in northeastern China were analyzed using amplified fragment length polymorphism (AFLP), specific-sequence amplified polymorphism (SSAP) and methylation-sensitive amplified polymorphism (MSAP) markers. Indices of (epi-)genetic diversity, (epi-)genetic distance, gene flow, genotype frequency, cluster analysis, PCA analysis and AMOVA analysis generated from MSAP, AFLP and SSAP markers had the same trend. We found a high level of correlation in the artificial populations between MSAP, SSAP and AFLP markers by the Mantel test (r > 0.8). This is incongruent with previous findings showing that there is virtually no correlation between DNA methylation polymorphism and classical genetic variation; the high level of genetic polymorphism could be a result of epigenetic regulation. We compared our results with data from natural populations. The population diversity of the artificial populations was lower. However, different from what was found using AFLP and SSAP, based on MSAP results the methylation polymorphism of the artificial populations was not significantly reduced. This leads us to suggest that the DNA methylation pattern change in H. brevisubulatum populations is not only related to DNA sequence variation, but is also regulated by other controlling systems.

No evidence of association of methylenetetrahydrofolate reductase polymorphism with occurrence of second neoplasms after treatment of childhood leukemia.

PubMed

Jazbec, Janez; Kitanovski, Lidija; Aplenc, Richard; Debeljak, Marusa; Dolzan, Vita

2005-06-01

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms have been associated not only with the risk for acute lymphoblastic leukemia (ALL) in adults and children, but also with increased methotrexate toxicity. The present study aimed to investigate whether MTHFR polymorphisms modify the risk for development of secondary malignancies in children treated for ALL with protocols that included high-dose methotrexate. MTHFR genotypes were determined in DNA samples isolated from archived bone marrow smears of 15 patients with a second malignancy and a matched control group of 30 patients who did not developed a second malignancy after the treatment for ALL. The frequencies of MTHFR C677T and A1298C genotypes in all patients were: C677T: CC 40%, CT 46.7% and TT 13.3% and A1298C: AA 46.7%, AC 44.4% and CC 8.9%. The relative risk for second malignancy was not significantly increased in ALL patients having at least one polymorphic C667T [odds ratio (OR) 1.51; 95% confidence interval (CI) 0.43-5.31] or one polymorphic A1298C allele (OR 1; 95% CI 0.29?-?3.46). Our study suggests that MTHFR polymorphisms are not associated with increased risk of second cancer in children treated with high-dose methotrexate.

A High Proportion of Chromosome 21 Promoter Polymorphisms Influence Transcriptional Activity

PubMed Central

Buckland, Paul R.; Coleman, Sharol L.; Hoogendoorn, Bastiaan; Guy, Carol; Smith, S. Kaye; O’Donovan, Michael C.

2004-01-01

We have sought to obtain an unbiased estimate of the proportion of polymorphisms in promoters of human genes that have functional effects. We carried out polymorphism discovery on a randomly selected group of 51 gene promoters mapping to human chromosome 21 and successfully analyzed the effect on transcription of 38 of the sequence variants. To achieve this, a total of 53 different haplotypes from 20 promoters were cloned into a modified pGL3 luciferase reporter gene vector and were tested for their abilities to promote transcription in HEK293t and JEG-3 cells. Up to seven (18%) of the 38 tested variants altered transcription by 1.5-fold, confirming that a surprisingly high proportion of promoter region polymorphisms are likely to be functionally important. The functional variants were distributed across the promoters of CRYAA, IFNAR1, KCNJ15, NCAM2, IGSF5, and B3GALT5. Three of the genes (NCAM2, IFNAR1, and CRYAA) have been previously associated with human phenotypes and the polymorphisms we describe here may therefore play a role in those phenotypes. PMID:15200235

Complete 13C NMR chemical shifts assignment for cholesterol crystals by combined CP-MAS spectral editing and ab initio GIPAW calculations with dispersion forces.

PubMed

Küçükbenli, Emine; Sonkar, Kanchan; Sinha, Neeraj; de Gironcoli, Stefano

2012-04-12

We report here the first fully ab initio determination of (13)C NMR spectra for several crystal structures of cholesterol, observed in various biomaterials. We combine Gauge-Including Projector Augmented Waves (GIPAW) calculations at relaxed structures, fully including dispersion forces, with Magic Angle Spinning Solid State NMR experiments and spectral editing to achieve a detailed interpretation of the complex NMR spectra of cholesterol crystals. By introducing an environment-dependent secondary referencing scheme in our calculations, not only do we reproduce the characteristic spectral features of the different crystalline polymorphs, thus clearly discriminating among them, but also closely represent the spectrum in the region of several highly overlapping peaks. This, in combination with spectral editing, allows us to provide a complete peak assignment for monohydrate (ChM) and low-temperature anhydrous (ChAl) crystal polymorphs. Our results show that the synergy between ab initio calculations and refined experimental techniques can be exploited for an accurate and efficient NMR crystallography of complex systems of great interest for biomaterial studies. The method is general in nature and can be applied for studies of various complex biomaterials.

Detection of single-nucleotide polymorphisms using gold nanoparticles and single-strand-specific nucleases.

PubMed

Chen, Yen-Ting; Hsu, Chiao-Ling; Hou, Shao-Yi

2008-04-15

The current study reports an assay approach that can detect single-nucleotide polymorphisms (SNPs) and identify the position of the point mutation through a single-strand-specific nuclease reaction and a gold nanoparticle assembly. The assay can be implemented via three steps: a single-strand-specific nuclease reaction that allows the enzyme to truncate the mutant DNA; a purification step that uses capture probe-gold nanoparticles and centrifugation; and a hybridization reaction that induces detector probe-gold nanoparticles, capture probe-gold nanoparticles, and the target DNA to form large DNA-linked three-dimensional aggregates of gold nanoparticles. At high temperature (63 degrees C in the current case), the purple color of the perfect match solution would not change to red, whereas a mismatched solution becomes red as the assembled gold nanoparticles separate. Using melting analysis, the position of the point mutation could be identified. This assay provides a convenient colorimetric detection that enables point mutation identification without the need for expensive mass spectrometry. To our knowledge, this is the first report concerning SNP detection based on a single-strand-specific nuclease reaction and a gold nanoparticle assembly.

Applications of NIR spectroscopy to monitoring and analyzing the solid state during industrial crystallization processes.

PubMed

Févotte, G; Calas, J; Puel, F; Hoff, C

2004-04-01

Fiber-optic near infrared (NIR) spectroscopy was used to investigate several key features of the polymorphic transitions observed during the crystallization and the filtration of SaC, an Active Pharmaceutical Ingredient (API) produced by Sanofi-Synthelabo. Using few samples, the spectroscopic data were calibrated to provide measurements of the polymorphic composition of the solid product which is likely to appear in two crystalline forms or in the amorphous state. Both qualitative and quantitative methods were successfully evaluated to characterize the API. The NIR spectroscopy measurement was then applied to investigate the kinetic behavior of the phase transition phenomena against various operating conditions. From the viewpoint of industrial process development several applications are presented. The effects of temperature and seed crystal habits on the rate of transition of filtration cakes are briefly investigated; and a study of the effect of residual water in the solvent on the transition occurring during filtration is more deeply analyzed. The experimental results demonstrate that highly valuable information can be provided by the NIR spectroscopy measurements, when one aims at understanding more deeply and optimizing the consequences of various and complex phenomena involved during the solid processing chain.

SLC2A9 and ZNF518B polymorphisms correlate with gout-related metabolic indices in Chinese Tibetan populations.

PubMed

Zhang, X Y; Geng, T T; Liu, L J; Yuan, D Y; Feng, T; Kang, L L; Jin, T B; Chen, C

2015-08-19

Current evidence suggests that heredity and metabolic syndrome contribute to gout progression. SLC2A9 and ZNF518B may play a role in gout progression in different populations, but no studies have focused on the Tibetan Chinese population. In this study, we determined whether variations in these 2 genes were correlated with gout-related indices in Chinese-Tibetan gout patients. We detected 6 single nucleotide polymorphisms in SLC2A9 and ZNF518B in 319 Chinese Tibetan gout patients. One-way analysis of variance was used to evaluate the polymorphisms' effects on gout based on mean serum levels of metabolism indicators. Polymorphisms in SLC2A9 and ZNF518B affected multiple risk factors related to gout development. Significant differences in serum triglyceride levels and high-density lipoprotein-cholesterol level were detected between different genotypic groups with SLC2A9 polymorphisms rs13129697 (P = 0.022), rs4447863 (P = 0.018), and rs1014290 (P = 0.045). Similarly in ZNF518B, rs3217 (P = 0.016) and rs10016022 (P = 0.046) were associated with high creatinine and glucose levels, respectively. This study is the first to investigate and identify positive correlations between SLC2A9 and ZNF518B gene polymorphisms and metabolic indices in Tibetan gout patients. We found significant evidence indicating that genetic polymorphisms affect gout-related factors in Chinese Tibetan populations.

Understanding polymorphism in organic semiconductor thin films through nanoconfinement.

PubMed

Diao, Ying; Lenn, Kristina M; Lee, Wen-Ya; Blood-Forsythe, Martin A; Xu, Jie; Mao, Yisha; Kim, Yeongin; Reinspach, Julia A; Park, Steve; Aspuru-Guzik, Alán; Xue, Gi; Clancy, Paulette; Bao, Zhenan; Mannsfeld, Stefan C B

2014-12-10

Understanding crystal polymorphism is a long-standing challenge relevant to many fields, such as pharmaceuticals, organic semiconductors, pigments, food, and explosives. Controlling polymorphism of organic semiconductors (OSCs) in thin films is particularly important given that such films form the active layer in most organic electronics devices and that dramatic changes in the electronic properties can be induced even by small changes in the molecular packing. However, there are very few polymorphic OSCs for which the structure-property relationships have been elucidated so far. The major challenges lie in the transient nature of metastable forms and the preparation of phase-pure, highly crystalline thin films for resolving the crystal structures and evaluating the charge transport properties. Here we demonstrate that the nanoconfinement effect combined with the flow-enhanced crystal engineering technique is a powerful and likely material-agnostic method to identify existing polymorphs in OSC materials and to prepare the individual pure forms in thin films at ambient conditions. With this method we prepared high quality crystal polymorphs and resolved crystal structures of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), including a new polymorph discovered via in situ grazing incidence X-ray diffraction and confirmed by molecular mechanic simulations. We further correlated molecular packing with charge transport properties using quantum chemical calculations and charge carrier mobility measurements. In addition, we applied our methodology to a [1]benzothieno[3,2-b][1]1benzothiophene (BTBT) derivative and successfully stabilized its metastable form.

Environmental Adaptation Contributes to Gene Polymorphism across the Arabidopsis thaliana Genome

PubMed Central

Lee, Cheng-Ruei

2012-01-01

The level of within-species polymorphism differs greatly among genes in a genome. Many genomic studies have investigated the relationship between gene polymorphism and factors such as recombination rate or expression pattern. However, the polymorphism of a gene is affected not only by its physical properties or functional constraints but also by natural selection on organisms in their environments. Specifically, if functionally divergent alleles enable adaptation to different environments, locus-specific polymorphism may be maintained by spatially heterogeneous natural selection. To test this hypothesis and estimate the extent to which environmental selection shapes the pattern of genome-wide polymorphism, we define the "environmental relevance" of a gene as the proportion of genetic variation explained by environmental factors, after controlling for population structure. We found substantial effects of environmental relevance on patterns of polymorphism among genes. In addition, the correlation between environmental relevance and gene polymorphism is positive, consistent with the expectation that balancing selection among heterogeneous environments maintains genetic variation at ecologically important genes. Comparison of the gene ontology annotations shows that genes with high environmental relevance are enriched in unknown function categories. These results suggest an important role for environmental factors in shaping genome-wide patterns of polymorphism and indicate another direction of genomic study. PMID:22798389

Polymorphic phase transitions and molecular motion in pyridinium chlorochromate

NASA Astrophysics Data System (ADS)

Pajaķ, Z.; Szafrańska, B.; Czarnecki, P.; Mayer, J.; Kozak, A.

1997-08-01

DTA, DSC, NMR and dielectric studies have been performed for pyridinium chlorochromate over a wide temperature range. A sequence of four solid-solid phase transitions was discovered. The in-plane complex reorientation of the cation is described by a three-well potential model with two correlation times. At higher temperatures one observes simultaneous cation tumbling and diffusion. Thus existence of a new ionic plastic phase is revealed. The domain structure observed suggests ferroelastic properties of the compound.

Superconductivity under high pressure in the binary compound CaLi2

NASA Astrophysics Data System (ADS)

Debessai, M.; Matsuoka, T.; Hamlin, J. J.; Gangopadhyay, A. K.; Schilling, J. S.; Shimizu, K.; Ohishi, Y.

2008-12-01

Feng predicted for CaLi2 highly anomalous properties with possible superconductivity under very high pressures, including for the hcp polymorph a significant lattice bifurcation at pressures above 47 GPa. More recently, however, Feng suggested that for pressures exceeding 20 GPa CaLi2 may dissociate into elemental Ca and Li. Here we present for hcp CaLi2 measurements of the electrical resistivity and ac susceptibility to low temperatures under pressures as high as 81 GPa. Pressure-induced superconductivity is observed in the pressure range of 11-81 GPa, with Tc reaching values as high as 13 K. X-ray diffraction studies to 54 GPa at 150 K reveal that hcp CaLi2 undergoes a structural phase transition above 23 GPa to orthorhombic but does not dissociate into elemental Ca and Li. In the hcp phase a fit of the equation of state with the Murnaghan equation yields the bulk modulus Bo=15(2)GPa and dBo/dP=3.2(6) .

Interesterification of engkabang (Shorea macrophylla) fat--canola oil blend with lipase from Candida antarctica to simulate the properties of lard.

PubMed

Illiyin, Mohamed Roslan Nur; Marikkar, Jalaldeen Mohamed Nazrim; Loke, Mei Key; Shuhaimi, Musthafa; Mahiran, Basri; Miskandar, Mat Saari

2014-01-01

A study was carried out to compare the composition and thermal properties of lard (LD) and engkabang fat (EF) - canola oil (CaO) blend interesterified with Candida antartica lipase (C. antartica). A fat blend EF-4 (40% EF in CaO) was prepared and interesterified using C. antartica lipase at 60°C for different time intervals (6 h, 12 h and 24 h) with 200 rpm agitation. The fat blends before and after interesterification were compared to LD with respect to their slip melting points (SMP), fatty acid and triacyglycerol (TAG) compositions, melting, solidification and polymorphic properties. Result showed that the slip melting point (SMP) of the fat blend interesterified for 6 h was the closest to that of LD. The solid fat content (SFC) values of fat blends interesterified for 12 and 24 h were found to become equal to those of LD within the temperature range of 0 to 20°C. In addition, all three interesterified blends had SFC values similar to those of LD within the temperature range of 30-40°C. According to thermal analysis, the transition of the fat blend interesterified for 24 h appearing at -2.39°C was similar to the low melting thermal transition of LD and the transition of the fat blend interesterified for 12 h appearing at 26.25°C was similar to the high melting thermal transition of LD. However, there is no compatibility between LD and all three interesterified blends with regard to polymorphic behaviour.

Polymorphic Transformation in Mixtures of High- and Low-Melting Fractions of Milk Fat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cisneros,A.; Mazzanti, G.; Campos, R.

2006-01-01

The kinetics of crystallization of high-melting fraction (HMF) and a mixture of 40% HMF and 60% low-melting fraction (LMF) of milk fat were studied at 5 C by time-resolved in-situ synchrotron X-ray diffraction. HMF crystallized in the {alpha} polymorph, had a longer lifetime than the ones previously reported in pure milk fat, and was almost completely solid. The HMF/LMF mixture crystallized initially in the {alpha} form and transformed into the {beta}' polymorph, with a solid fat content much lower than that of HMF. The polymorphic change was therefore attributed to a delayed sudden formation of {beta}' mixed crystals from themore » uncrystallized melt. These findings are important for the food industry and as fundamental knowledge to improve our understanding of the origin of the macroscopic physical properties of solid milk fat fractions used in many manufacturing processes.« less

The influence of folate pathway polymorphisms on high-dose methotrexate-related toxicity and survival in children with non-Hodgkin malignant lymphoma

PubMed Central

Erculj, Nina; Kotnik, Barbara Faganel; Debeljak, Marusa; Jazbec, Janez; Dolzan, Vita

2014-01-01

Background We evaluated the influence of folate pathway polymorphisms on high-dose methotrexate (HD-MTX) related toxicity in paediatric patients with T-cell non-Hodgkin lymphoma (NHL). Patients and methods In total, 30 NHL patients were genotyped for selected folate pathway polymorphisms. Results Carriers of at least one MTHFR 677T allele had significantly higher MTX area under the time-concentration curve levels at third MTX cycle (P = 0.003). These patients were also at higher odds of leucopoenia (P = 0.006) or thrombocytopenia (P = 0.041) and had higher number of different HD-MTX-related toxicity (P = 0.035) compared to patients with wild-type genotype. Conclusions Our results suggest an important role of MTHFR 677C>T polymorphism in the development of HD-MTX-related toxicity in children with NHL. PMID:25177243

Relationship between Job Stress and 5-HT2A Receptor Polymorphisms on Self-Reported Sleep Quality in Physicians in Urumqi (Xinjiang, China): A Cross-Sectional Study

PubMed Central

Ge, Hua; Jiang, Yu; Zhang, Chen; Liu, Jiwen

2018-01-01

The serotonin receptor (5-HTR) plays a key role in sleep quality regulation. Job-related stress is an important factor that influences sleep quality. However, few reports on the interaction between 5-HTR2A polymorphisms and job stress, and how they may impact upon sleep quality are available. Therefore this study investigated the effects of job stress, 5-HTR2A polymorphisms, and their interaction on sleep quality, in physicians. Using a two-stage stratified sampling method, 918 participants were initially invited to participate in the study. After screening for study inclusion and exclusion criteria, 504 subjects were eventually included in the study. Job stress and sleep quality were assessed using the Job Stress Survey (JSS) and Pittsburgh Sleep Quality Index (PSQI), respectively. The 5-HTR2A receptor gene polymorphisms T102C and -1438G/A of were determined using polymerase chain reaction-restriction fragment length polymorphism. Job stress was significantly associated with sleep quality. High levels of job stress were linked to a higher risk of poor sleep quality compared to low or moderate levels [odds ratio (OR) = 2.909, 95% confidence interval (CI): 1.697–4.986]. High levels of stress may reduce subjects’ sleep quality, leading to an increase the likelihood of sleep disturbances and subsequent daytime dysfunction. The 5-HTR2A receptor gene polymorphism T102C was not significantly associated with sleep quality in this study, however, the -1438G/A polymorphism was significantly associated with sleep quality. The GG genotype of the -1438G/A polymorphism was linked to poorer sleep quality. When compared with subjects with low job-related stress levels×AG/AA genotype (OR = 2.106, 95% CI: 1.278–3.471), physicians with high job-related stress levels×GG genotype had a higher risk of experiencing poor sleep quality (OR = 13.400, 95% CI: 3.143–57.137). The findings of our study indicate that job stress and 5-HTR2A receptor gene polymorphisms are associated with sleep quality in physicians. Subjects with high job stress level or/and the -1438G/A GG genotype were more likely to report poor sleep quality, and furthermore, their combination effect on sleep quality was higher than their independent effects, so it may be suggested that job-related stress and genes have a cumulative effect on sleep quality; that is, stress can increase the risk of poor sleep quality, but this effect is worse in a group of people with specific gene polymorphisms. PMID:29883419

Relationship between Job Stress and 5-HT2A Receptor Polymorphisms on Self-Reported Sleep Quality in Physicians in Urumqi (Xinjiang, China): A Cross-Sectional Study.

PubMed

Gao, Xiaoyan; Ge, Hua; Jiang, Yu; Lian, Yulong; Zhang, Chen; Liu, Jiwen

2018-05-21

The serotonin receptor (5-HTR) plays a key role in sleep quality regulation. Job-related stress is an important factor that influences sleep quality. However, few reports on the interaction between 5-HTR2A polymorphisms and job stress, and how they may impact upon sleep quality are available. Therefore this study investigated the effects of job stress, 5-HTR2A polymorphisms, and their interaction on sleep quality, in physicians. Using a two-stage stratified sampling method, 918 participants were initially invited to participate in the study. After screening for study inclusion and exclusion criteria, 504 subjects were eventually included in the study. Job stress and sleep quality were assessed using the Job Stress Survey (JSS) and Pittsburgh Sleep Quality Index (PSQI), respectively. The 5-HTR2A receptor gene polymorphisms T102C and -1438G/A of were determined using polymerase chain reaction-restriction fragment length polymorphism. Job stress was significantly associated with sleep quality. High levels of job stress were linked to a higher risk of poor sleep quality compared to low or moderate levels [odds ratio (OR) = 2.909, 95% confidence interval (CI): 1.697⁻4.986]. High levels of stress may reduce subjects’ sleep quality, leading to an increase the likelihood of sleep disturbances and subsequent daytime dysfunction. The 5-HTR2A receptor gene polymorphism T102C was not significantly associated with sleep quality in this study, however, the -1438G/A polymorphism was significantly associated with sleep quality. The GG genotype of the -1438G/A polymorphism was linked to poorer sleep quality. When compared with subjects with low job-related stress levels×AG/AA genotype (OR = 2.106, 95% CI: 1.278⁻3.471), physicians with high job-related stress levels×GG genotype had a higher risk of experiencing poor sleep quality (OR = 13.400, 95% CI: 3.143⁻57.137). The findings of our study indicate that job stress and 5-HTR2A receptor gene polymorphisms are associated with sleep quality in physicians. Subjects with high job stress level or/and the -1438G/A GG genotype were more likely to report poor sleep quality, and furthermore, their combination effect on sleep quality was higher than their independent effects, so it may be suggested that job-related stress and genes have a cumulative effect on sleep quality; that is, stress can increase the risk of poor sleep quality, but this effect is worse in a group of people with specific gene polymorphisms.

Widespread utility of highly informative AFLP molecular markers across divergent shark species.

PubMed

Zenger, Kyall R; Stow, Adam J; Peddemors, Victor; Briscoe, David A; Harcourt, Robert G

2006-01-01

Population numbers of many shark species are declining rapidly around the world. Despite the commercial and conservation significance, little is known on even the most fundamental aspects of their population biology. Data collection that relies on direct observation can be logistically challenging with sharks. Consequently, molecular methods are becoming increasingly important to obtain knowledge that is critical for conservation and management. Here we describe an amplified fragment length polymorphism method that can be applied universally to sharks to identify highly informative genome-wide polymorphisms from 12 primer pairs. We demonstrate the value of our method on 15 divergent shark species within the superorder Galeomorphii, including endangered species which are notorious for low levels of genetic diversity. Both the endangered sand tiger shark (Carcharodon taurus, N = 18) and the great white shark (Carcharodon carcharias, N = 7) displayed relatively high levels of allelic diversity. A total of 59 polymorphic loci (H(e) = 0.373) and 78 polymorphic loci (H(e) = 0.316) were resolved in C. taurus and C. carcharias, respectively. Results from other sharks (e.g., Orectolobus ornatus, Orectolobus sp., and Galeocerdo cuvier) produced remarkably high numbers of polymorphic loci (106, 94, and 86, respectively) from a limited sample size of only 2. A major constraint to obtaining much needed genetic data from sharks is the time-consuming process of developing molecular markers. Here we demonstrate the general utility of a technique that provides large numbers of informative loci in sharks.

A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.

PubMed

Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

2014-06-28

Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

Detection of AGXT bgene mutations by denaturing high-performance liquid chromatography for diagnosis of hyperoxaluria type 1.

PubMed

Pirulli, D; Giordano, M; Lessi, M; Spanò, A; Puzzer, D; Zezlina, S; Boniotto, M; Crovella, S; Florian, F; Marangella, M; Momigliano-Richiardi, P; Savoldi, S; Amoroso, A

2001-06-01

Primary hyperoxaluria type 1 is an autosomal recessive disorder of glyoxylate metabolism, caused by a deficiency of alanine:glyoxylate aminotransferase, which is encoded by a single copy gene (AGXT. The aim of this research was to standardize denaturing high-performance liquid chromatography, a new, sensitive, relatively inexpensive, and automated technique, for the detection of AGXT mutation. Denaturing high-performance liquid chromatography was used to analyze in blind the AGXT gene in 20 unrelated Italian patients with primary hyperoxaluria type I previously studied by other standard methods (single-strand conformation polymorphism analysis and direct sequencing) and 50 controls. Denaturing high-performance liquid chromatography allowed us to identify 13 mutations and the polymorphism at position 154 in exon I of the AGXT gene. Hence the method is more sensitive and less time consuming than single-strand conformation polymorphism analysis for the detection of AGXT mutations, thus representing a useful and reliable tool for detecting the mutations responsible for primary hyperoxaluria type 1. The new technology could also be helpful in the search for healthy carriers of AGXT mutations amongst family members and their partners, and for screening of AGXT polymorphisms in patients with nephrolithiasis and healthy populations.

Genetic variation within and among populations of Rhodiola alsia (Crassulaceae) native to the Tibetan Plateau as detected by ISSR markers.

PubMed

Xia, Tao; Chen, Shilong; Chen, Shengyun; Ge, Xuejun

2005-04-01

Genetic variation of 10 Rhodiola alsia (Crassulaceae) populations from the Qinghai-Tibet Plateau of China was investigated using intersimple sequence repeat (ISSR) markers. R. alsia is an endemic species of the Qinghai-Tibet Plateau. Of the 100 primers screened, 13 were highly polymorphic. Using these primers, 140 discernible DNA fragments were generated with 112 (80%) being polymorphic, indicating pronounced genetic variation at the species level. Also there were high levels of polymorphism at the population level with the percentage of polymorphic bands (PPB) ranging from 63.4 to 88.6%. Analysis of molecular variance (AMOVA) showed that the genetic variation was mainly found among populations (70.3%) and variance within populations was 29.7%. The main factors responsible for the high level of differentiation among populations are probably the isolation from other populations and clonal propagation of this species. Occasional sexual reproduction might occur in order to maintain high levels of variation within populations. Environmental conditions could also influence population genetic structure as they occur in severe habitats. The strong genetic differentiation among populations in our study indicates that the conservation of genetic variability in R. alsia requires maintenance of as many populations as possible.

Positive Association of D Allele of ACE Gene With High Altitude Pulmonary Edema in Indian Population.

PubMed

Bhagi, Shuchi; Srivastava, Swati; Tomar, Arvind; Bala Singh, Shashi; Sarkar, Soma

2015-06-01

High altitude pulmonary edema (HAPE) is a potentially fatal high altitude illness occurring as a result of hypobaric hypoxia with an unknown underlying genetic mechanism. Recent studies have shown a possible association between HAPE and polymorphisms in genes of the renin-angiotensin-aldosterone system (RAAS), which play a key role in sensitivity of an individual toward HAPE. For the present investigation, study groups consisted of HAPE patients (HAPE) and acclimatized control subjects (rCON). Four single-nucleotide polymorphisms (SNPs) were genotyped using restriction fragment length polymorphism (RFLP) analysis in genes of the RAAS pathway, specifically, renin (REN) C(-4063)T (rs41317140) and RENi8-83 (rs2368564), angiotensin (AGT) M(235)T (rs699), and angiotensin-converting enzyme (ACE) insertion/deletion (I/D) (rs1799752). Only the I/D polymorphism of the ACE gene showed a significant difference between the HAPE and rCON groups. The frequency of the D allele was found to be significantly higher in the HAPE group. Arterial oxygen saturation levels were significantly lower in the HAPE group compared with the rCON group and also decreased in the I/D and D/D genotypes compared with the I/I genotype in these groups. The other polymorphisms occurring in the REN and AGT genes were not significantly different between the 2 groups. These findings demonstrate a possible association of the I/D polymorphism of the ACE gene with the development of HAPE, with D/D being the at-risk genotype. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

AFLP marking and polymorphism among progenies of Gymnema sylvestre: an important medicinal plant of India.

PubMed

Osman, Magda Abbaker; Dhawan, Sunita Singh; Bahl, Janak Raj; Darokar, Mahendra P; Khanuja, Suman P S

2011-11-01

The level of polymorphism among twelve selected progenies of Gymnema sylvestre was investigated through AFLP markers by multiplexing PCR reactions using 64 (8x8) primer combinations. Fourteen primer combinations were selected as the most suitable combination for G. sylvestre. Analysis of the 12 progenies with these 14 primer pairs produced 1689 fragments of which 972 (57.5%) were polymorphic and 485 (28.7%) were unique to a particular genotype. The number of fragments produced by individual primer pairs was in the range of 55 to 225. Out of these, polymorphic fragments were in the range of 34 (E-ACC/M-CAC) to 157 (E-AGG/M-CAG) and unique bands observed were 8 (E-ACC / M-CAC) to 69 (E-AGG/M-CAC). Different primer combinations detected different levels of polymorphism, ranging from 33% (E-AGG/ M-CAC) to 69.8% (E-AGG/ M-CAC). From the observations, it appears that the primer combinations E-AGG/M-CAC, E-AGG/CTG, E-AGG/CAG and E-ACA/CAT were the most informative for the detection of polymorphism among the progenies compared with others, since they produced a high number of unique fragments. The similarity coefficient ranged from 0.212 to 0.731. High similarity was observed between progeny S8 and S9 (73%) and high divergence between progenies S3 and S11. Among the selected progeny, S9 was found to be the most similar to the parent (63%), while genotype S11 was the most distant (36.9%).

Prion gene haplotypes of U.S. cattle

PubMed Central

Clawson, Michael L; Heaton, Michael P; Keele, John W; Smith, Timothy PL; Harhay, Gregory P; Laegreid, William W

2006-01-01

Background Bovine spongiform encephalopathy (BSE) is a fatal neurological disorder characterized by abnormal deposits of a protease-resistant isoform of the prion protein. Characterizing linkage disequilibrium (LD) and haplotype networks within the bovine prion gene (PRNP) is important for 1) testing rare or common PRNP variation for an association with BSE and 2) interpreting any association of PRNP alleles with BSE susceptibility. The objective of this study was to identify polymorphisms and haplotypes within PRNP from the promoter region through the 3'UTR in a diverse sample of U.S. cattle genomes. Results A 25.2-kb genomic region containing PRNP was sequenced from 192 diverse U.S. beef and dairy cattle. Sequence analyses identified 388 total polymorphisms, of which 287 have not previously been reported. The polymorphism alleles define PRNP by regions of high and low LD. High LD is present between alleles in the promoter region through exon 2 (6.7 kb). PRNP alleles within the majority of intron 2, the entire coding sequence and the untranslated region of exon 3 are in low LD (18.0 kb). Two haplotype networks, one representing the region of high LD and the other the region of low LD yielded nineteen different combinations that represent haplotypes spanning PRNP. The haplotype combinations are tagged by 19 polymorphisms (htSNPS) which characterize variation within and across PRNP. Conclusion The number of polymorphisms in the prion gene region of U.S. cattle is nearly four times greater than previously described. These polymorphisms define PRNP haplotypes that may influence BSE susceptibility in cattle. PMID:17092337

Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

DOE PAGES

Kaercher, Pamela M.; Zepeda-Alarcon, Eloisa; Prakapenka, Vitali B.; ...

2014-11-07

Although the crystal structure of the high pressure SiO 2 polymorph stishovite has been studied in detail, little is known about the development of crystallographic preferred orientation (CPO) during deformation in stishovite. Insight into CPO and associated deformation mechanics of stishovite would provide important information for understanding subduction of quartz-bearing crustal rocks into the mantle. To study CPO development, we converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. We collected diffraction patterns in radial geometry to examine in situ development of crystallographic preferred orientationmore » and find that (001) poles preferentially align with the compression direction. Viscoplastic self-consistent modeling suggests the most likely slip systems at high pressure and ambient temperature are pyramidal and basal slip.« less

Ab initio random structure searching of organic molecular solids: assessment and validation against experimental data.

PubMed

Zilka, Miri; Dudenko, Dmytro V; Hughes, Colan E; Williams, P Andrew; Sturniolo, Simone; Franks, W Trent; Pickard, Chris J; Yates, Jonathan R; Harris, Kenneth D M; Brown, Steven P

2017-10-04

This paper explores the capability of using the DFT-D ab initio random structure searching (AIRSS) method to generate crystal structures of organic molecular materials, focusing on a system (m-aminobenzoic acid; m-ABA) that is known from experimental studies to exhibit abundant polymorphism. Within the structural constraints selected for the AIRSS calculations (specifically, centrosymmetric structures with Z = 4 for zwitterionic m-ABA molecules), the method is shown to successfully generate the two known polymorphs of m-ABA (form III and form IV) that have these structural features. We highlight various issues that are encountered in comparing crystal structures generated by AIRSS to experimental powder X-ray diffraction (XRD) data and solid-state magic-angle spinning (MAS) NMR data, demonstrating successful fitting for some of the lowest energy structures from the AIRSS calculations against experimental low-temperature powder XRD data for known polymorphs of m-ABA, and showing that comparison of computed and experimental solid-state NMR parameters allows different hydrogen-bonding motifs to be discriminated.

Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

NASA Astrophysics Data System (ADS)

Shi, Fa-Nian; Ananias, Duarte; Yang, Ting-Hai; Rocha, João

2013-08-01

A novel metal organic framework (MOF) formulated as [Eu(H2O)2(fdc)(ox)0.5·(H2O)]n (1, fdc2-=2,5-furandicarboxylate, ox2-=oxalate), was hydrothermally synthesized via in situ ox2- generation from the partial decomposition of the fdc2- ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) Å, β=116.917(2)° (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H2O, ox2-and fdc2-) via hydrogen bonding interactions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu3+ red emission and the differences observed reflects the slightly different structures of these polymorphs.

Association between TLR2 and TLR4 Gene Polymorphisms and the Susceptibility to Inflammatory Bowel Disease: A Meta-Analysis

PubMed Central

Huang, Xiuping; Zhang, Wei; Han, Zelong; Liu, Side

2015-01-01

Background The associations between toll-like receptor 2 (TLR2) and toll-like receptor 4(TLR4) polymorphisms and inflammatory bowel disease (IBD) susceptibility remain controversial. A meta-analysis was performed to assess these associations. Methods A systematic search was performed to identify all relevant studies relating TLR2 and TLR4 polymorphisms and IBD susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed by ethnicity and publication quality. Results Thirty-eight eligible studies, assessing 10970 cases and 7061 controls were included. No TLR2 Arg677Trp polymorphism was found. No significant association was observed between TLR2 Arg753Gln polymorphism and Crohn’s disease (CD) or ulcerative colitis (UC) in all genetic models. Interestingly, TLR4 Asp299Gly polymorphism was significantly associated with increased risk of CD and UC in all genetic models, except for the additive one in CD. In addition, a statistically significant association between TLR4 Asp299Gly polymorphism and IBD was observed among high quality studies evaluating Caucasians, but not Asians. Associations between TLR4 Thr399Ile polymorphisms and CD risk were found only in the allele and dominant models. The TLR4 Thr399Ile polymorphism was associated with UC risk in pooled results as well as subgroup analysis of high quality publications assessing Caucasians, in allele and dominant models. Conclusions The meta-analysis provides evidence that TLR2 Arg753Gln is not associated with CD and UC susceptibility in Asians; TLR4 Asp299Gly is associated with CD and UC susceptibility in Caucasians, but not Asians. TLR4 Thr399Ile may be associated with IBD susceptibility in Caucasians only. Additional well-powered studies of Asp299Gly and other TLR4 variants are warranted. PMID:26023918

Prothrombin polymorphism A19911G, factor V HR2 haplotype A4070G, and plasminogen activator-inhibitor-1 polymorphism 4G/5G and the risk of retinal vein occlusion.

PubMed

Kuhli-Hattenbach, Claudia; Hellstern, Peter; Nägler, Dorit Karin; Kohnen, Thomas; Hattenbach, Lars-Olof

2017-01-01

Thus far, no data has become available to evaluate systematically the prevalences of prothrombin polymorphism A19911G (PT A19911G), factor V HR2 haplotype A4070G (FV A4070G), or plasminogen activator-inhibitor-1 polymorphism 4G/5G (PAI-1 4G/5G) in patients who develop retinal vein occlusion (RVO) without cardiovascular risk factors. We retrospectively evaluated comprehensive thrombophilia data from 42 preselected RVO patients without cardiovascular risk factors. The prevalences of different gene mutations and polymorphisms including factor V Leiden mutation G1691A (FVL), FV A4070G, prothrombin mutation G20210A, PT A19911G, and PAI-1 4G/5G were compared with 241 healthy controls matched for age and sex. A total of 20 patients (47.7%) were found to carry thrombophilic gene polymorphisms including FVL, FV A4070G, and homozygous PT A19911G compared with 72 of 241 controls (29.9%; p = 0.03). Subgroup analysis of patients with a significant personal or family history of thromboembolism revealed a high prevalence of FVL, FV A4070G, and homozygous PT A19911G (p = 0.005). FV A4070G was found to be significantly associated with at least two other heterozygous or one homozygous gene polymorphisms (p = 0.02). Multivariate analysis revealed the presence of FVL (p = 0.0017) and homozygous PT A19911G (p = 0.03) polymorphism as independent risk factors for the development of RVO. Our results indicate that in selected RVO patients screening for thrombophilic gene polymorphisms including FVL, FV A4070G and homozygous PT G19911A may be helpful in a high percentage of cases. Our findings suggest that hereditary thrombophilia associated with RVO is more likely to be multigenic than caused by any single risk factor.

Transient receptor potential melastatin 8 gene polymorphism is associated with cold-induced airway hyperresponsiveness in bronchial asthma.

PubMed

Naumov, Denis E; Perelman, Juliy M; Kolosov, Victor P; Potapova, Tatyana A; Maksimov, Vladimir N; Zhou, Xiangdong

2015-11-01

Cold-induced airway hyperresponsiveness (CAH) is common in bronchial asthma (BA) patients and represents a problem for those living in cold climate. Transient receptor potential melastatin 8 (TRPM8) channel is the main cold temperature sensor in humans that could mediate cold response in asthmatics with CAH. No associations between TRPM8 gene polymorphisms and CAH have been reported. The present study involved 123 BA patients. CAH was assessed by 3-min isocapnic (5% CO2 ) cold air (-20°C) hyperventilation challenge. The c.750G > C (rs11562975), c.1256G > A (rs7593557), c.3048C > T (rs11563208) and c.3174C > G (rs11563071) polymorphisms of TRPM8 gene were genotyped by allele-specific polymerase chain reaction (PCR) and PCR with subsequent restriction fragment length polymorphism analysis. GC genotype and C allele carriers of the c.750G > C (rs11562975) polymorphism were more frequently observed to exhibit CAH. The estimated odds ratio for the GC genotype was 3.73 95%CI (1.48; 9.37), P = 0.005. Furthermore, GC heterozygotes had a prominent decrease in forced expiratory volume in 1 s after the challenge as compared to GG homozygotes (-12% (-16; -8.1) vs -6.45% (-11; -2.1), P < 0.001). GC carriers also had a marked reduction in other spirometric parameters. The GC variant of the TRPM8:c.750G > C (rs11562975) polymorphism is associated with CAH in patients with BA, which suggests a potential role of TRPM8 in CAH development. © 2015 Asian Pacific Society of Respirology.

Shock-induced deformation of Shergottites: Shock-pressures and perturbations of magmatic ages on Mars

NASA Astrophysics Data System (ADS)

El Goresy, Ahmed; Gillet, Ph.; Miyahara, M.; Ohtani, E.; Ozawa, S.; Beck, P.; Montagnac, G.

2013-01-01

Shergottites and Chassignites practiced major deformation effects whose nature, magnitude and relevance were controversially evaluated and disputatively debated. Our studies of many shocked shergottites present, contrary to numerous previous reports, ample evidence for pervasive shock-induced melting amounting of at least 23 vol.% of the shergottite consisting of maskelynite and pyrrhotite, partial melting of pyroxene, titanomagnetite, ilmenite and finding of several high-pressure polymorphs and pressure-induced dissociation reactions. Our results cast considerable doubt on using the refractive index (RI) or cathodoluminescence (CL) spectra of maskelynite, in estimating the magnitudes of peak-shock pressure in both shergottites and ordinary chondrites. RI of maskelynite was set after quenching of the feldspar liquid before decompression to maskelynite glass followed by glass relaxation after decompression at the closure temperature of relaxation. The RI procedure widely practiced in the past 38 years revealed unrealistic very high-pressure estimates discrepant with the high-pressure mineral inventory in shocked shergottites and ordinary chondrites and with results obtained by robust laboratory static experiments. Shergottites contain the silica high-pressure polymorphs: the scrutinyite-structured polymorph seifertite, a monoclinic ultra dense polymorph of silica with ZrO2-structure, stishovite, a dense liquidus assemblage consisting of stishovite + Na-hexa-aluminosilicate (Na-CAS) and both K-lingunite and Ca-lingunite. Applying individual high-pressure silica polymorphs alone like stishovite, to estimate the equilibrium shock pressure, is inadequate due to the considerable shift of their nominal upper pressure bounds intrinsically induced by spatially variable absorptions of minor oxides like Al2O3, Na2O, FeO, MgO and TiO2. This practice revealed variable pressure estimates even within the same shergottite subjected to the same peak-shock pressure. Occurrence of Na-CAS + stishovite, lack of the NaAlSiO4 Ca-ferrite structured polymorph or jadeite indicates that the peak-shock pressures barely exceeded 22 GPa. We present convincing and ample evidence refuting the claim that the shock-induced high-pressure inventory in shergottites and ordinary chondrites are disequilibrium assemblages resulted from local pressure spikes in excess of 80 GPa and during the decompression stage. Such scenario calls for a series of incomplete and quenched retrograde reactions starting with the crystallization of Mg-silicate perovskite + magnesiowüstite, if the claimed peak-shock pressure was in excess of 80 GPa. This would be followed by replacement of this pair by majorite-pyropess + magnesiowüstite or akimotoite + magnesiowüstite below 23 GPa and 2000 °C, polycrystalline ringwoodite above 16 GPa, respectively and finally replacement by polycrystalline olivine below 16 GPa. Such incomplete retrograde reactions were never encountered in any shergottite, chassignite or shocked ordinary chondrite so far. Olivine-ringwoodite phase transformation in the L6 Y-791384 commences with the coherent mechanism producing ringwoodite lamellae with their (1 1 1) planes parallel to the (1 0 0) of olivine followed by the incoherent mechanism due to build up of strain in the parental olivine. This is in accord with the olivine-ringwoodite settings produced in static laboratory experiments in a multi-anvil device. Olivine-ringwoodite phase transitions were also encountered in comparable settings in the shergottite NWA 1068. Application of experimentally obtained kinetic parameters of the olivine-ringwoodite phase transitions reveals possible duration of the natural dynamic events up to few seconds thus unambiguously refuting the claimed disequilibrium decompression mechanism. The shock-induced pervasive melting of labradorite, pyrrhotite, titanomagnetite, ilmenite and partial melting of clinopyroxene strongly suggests shock-induced partial to complete resetting of the Ar-Ar, Rb-Sr, Sm-Nd, Re-Os, U-Pb and Lu-Hf radiometric systems. This also casts considerable doubt on the radiometric ages shorter than 575 Ma reported in the past 38 years to allegedly be the igneous crystallization ages. These short ages probably resulted from partial or total shock-induced age resetting.

Neutron diffraction and μ SR studies of two polymorphs of nickel niobate NiNb 2 O 6

DOE PAGES

Munsie, T. J. S.; Wilson, M. N.; Millington, A.; ...

2017-10-13

Neutron diffraction and muon spin relaxation (μSR) studies are presented in this paper for the newly characterized polymorph of NiNb 2O 6 (β-NiNb 2O 6) with space group P4 2/n and μSR data only for the previously known columbite structure polymorph with space group Pbcn. The magnetic structure of the P4 2/n form was determined from neutron diffraction using both powder and single-crystal data. Powder neutron diffraction determined an ordering wave vector →k=( 1/ 2, 1/ 2, 1/ 2). Single-crystal data confirmed the same →k vector and showed that the correct magnetic structure consists of antiferromagnetically coupled chains running alongmore » the a or b axis in adjacent Ni 2+ layers perpendicular to the c axis, which is consistent with the expected exchange interaction hierarchy in this system. The refined magnetic structure is compared with the known magnetic structures of the closely related trirutile phases, NiSb 2O 6 and NiTa 2O 6. μSR data finds a transition temperature of T N~15K for this system, while the columbite polymorph exhibits a lower T N=5.7(3) K. Our μSR measurements also allowed us to estimate the critical exponent of the order parameter β for each polymorph. We found β =0.25(3) and 0.16(2) for the β and columbite polymorphs, respectively. The single-crystal neutron scattering data give a value for the critical exponent β =0.28(3) for β-NiNb 2O 6, in agreement with the μSR value. While both systems have β values less than 0.3, which is indicative of reduced dimensionality, this effect appears to be much stronger for the columbite system. Finally, in other words, although both systems appear to be well described by S=1 spin chains, the interchain interactions in the β polymorph are likely much larger.« less

Neutron diffraction and μ SR studies of two polymorphs of nickel niobate NiNb2O6

NASA Astrophysics Data System (ADS)

Munsie, T. J. S.; Wilson, M. N.; Millington, A.; Thompson, C. M.; Flacau, R.; Ding, C.; Guo, S.; Gong, Z.; Aczel, A. A.; Cao, H. B.; Williams, T. J.; Dabkowska, H. A.; Ning, F.; Greedan, J. E.; Luke, G. M.

2017-10-01

Neutron diffraction and muon spin relaxation (μ SR ) studies are presented for the newly characterized polymorph of NiNb2O6 (β -NiNb2O6) with space group P4 2/n and μ SR data only for the previously known columbite structure polymorph with space group P b c n . The magnetic structure of the P4 2/n form was determined from neutron diffraction using both powder and single-crystal data. Powder neutron diffraction determined an ordering wave vector k ⃗=(1/2 ,1/2 ,1/2 ) . Single-crystal data confirmed the same k ⃗ vector and showed that the correct magnetic structure consists of antiferromagnetically coupled chains running along the a or b axis in adjacent Ni2 + layers perpendicular to the c axis, which is consistent with the expected exchange interaction hierarchy in this system. The refined magnetic structure is compared with the known magnetic structures of the closely related trirutile phases, NiSb2O6 and NiTa2O6 . μ SR data finds a transition temperature of TN˜15 K for this system, while the columbite polymorph exhibits a lower TN=5.7 (3 ) K. Our μ SR measurements also allowed us to estimate the critical exponent of the order parameter β for each polymorph. We found β =0.25 (3 ) and 0.16(2) for the β and columbite polymorphs, respectively. The single-crystal neutron scattering data give a value for the critical exponent β =0.28 (3 ) for β -NiNb2O6 , in agreement with the μ SR value. While both systems have β values less than 0.3, which is indicative of reduced dimensionality, this effect appears to be much stronger for the columbite system. In other words, although both systems appear to be well described by S =1 spin chains, the interchain interactions in the β polymorph are likely much larger.

Neutron diffraction and μ SR studies of two polymorphs of nickel niobate NiNb 2 O 6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munsie, T. J. S.; Wilson, M. N.; Millington, A.

Neutron diffraction and muon spin relaxation (μSR) studies are presented in this paper for the newly characterized polymorph of NiNb 2O 6 (β-NiNb 2O 6) with space group P4 2/n and μSR data only for the previously known columbite structure polymorph with space group Pbcn. The magnetic structure of the P4 2/n form was determined from neutron diffraction using both powder and single-crystal data. Powder neutron diffraction determined an ordering wave vector →k=( 1/ 2, 1/ 2, 1/ 2). Single-crystal data confirmed the same →k vector and showed that the correct magnetic structure consists of antiferromagnetically coupled chains running alongmore » the a or b axis in adjacent Ni 2+ layers perpendicular to the c axis, which is consistent with the expected exchange interaction hierarchy in this system. The refined magnetic structure is compared with the known magnetic structures of the closely related trirutile phases, NiSb 2O 6 and NiTa 2O 6. μSR data finds a transition temperature of T N~15K for this system, while the columbite polymorph exhibits a lower T N=5.7(3) K. Our μSR measurements also allowed us to estimate the critical exponent of the order parameter β for each polymorph. We found β =0.25(3) and 0.16(2) for the β and columbite polymorphs, respectively. The single-crystal neutron scattering data give a value for the critical exponent β =0.28(3) for β-NiNb 2O 6, in agreement with the μSR value. While both systems have β values less than 0.3, which is indicative of reduced dimensionality, this effect appears to be much stronger for the columbite system. Finally, in other words, although both systems appear to be well described by S=1 spin chains, the interchain interactions in the β polymorph are likely much larger.« less

The effect of a promoter polymorphism on the transcription of nitric oxide synthase 1 and its relevance to Parkinson's disease.

PubMed

Rife, Terrie; Rasoul, Bareza; Pullen, Nicholas; Mitchell, David; Grathwol, Kristen; Kurth, Janice

2009-08-01

Transcriptional changes of the enzyme nitric oxide synthase I (NOS1) are believed to play a role in the development of many diseases. The gene for NOS1 has 12 alternative first exons (1A-1L). The 1F exon is one of the most highly utilized first exons in the brain and has a polymorphism ((TG)(m)TA(TG)(n)) located in its promoter region. The polymorphism's length has been suggested to affect NOS1 transcription and play a role in Parkinson's disease (PD); however, the actual influence of the polymorphism on NOS1 transcription has not been studied. To better characterize the links of the polymorphism with PD, a genotyping study was done comparing polymorphism length among 170 PD patients and 150 age-matched controls. The pattern of changes between the two group's allele frequencies shows statistical significance (P = 0.0359). The smallest polymorphism sizes are more predominant among PD patients than controls. To study the effects of this polymorphism on NOS1 gene transcription, reporter gene constructs were made by cloning the NOS1 1F promoter with polymorphism lengths of either 42, 54, or 62 bp in front of the luciferase gene and transfecting them into HeLa or Sk-N-MC cells. NOS1-directed reporter gene constructs with the 62-bp polymorphism increased transcription of luciferase 2.2-fold in HeLa and 1.8-fold in Sk-N-MC cells compared with reporter gene constructs with the 42-bp polymorphism. These data suggest that if smaller polymorphism size contributes to the higher NOS1 levels in PD patients, an as yet unknown transcriptional mechanism is required. Copyright 2009 Wiley-Liss, Inc.

Quantitative trait loci controlling leaf appearance and curd initiation of cauliflower in relation to temperature.

PubMed

Hasan, Yaser; Briggs, William; Matschegewski, Claudia; Ordon, Frank; Stützel, Hartmut; Zetzsche, Holger; Groen, Simon; Uptmoor, Ralf

2016-07-01

QTL regions on chromosomes C06 and C09 are involved in temperature dependent time to curd induction in cauliflower. Temperature is the main environmental factor influencing curding time of cauliflower (Brassica oleracea var. botrytis). Temperatures above 20-22 °C inhibit development towards curding even in many summer cultivars. To identify quantitative trait loci (QTL) controlling curding time and its related traits in a wide range of different temperature regimes from 12 to 27 °C, a doubled haploid (DH) mapping population segregating for curding time was developed and days to curd initiation (DCI), leaf appearance rate (LAR), and final leaf number (FLN) were measured. The population was genotyped with 176 single nucleotide polymorphism (SNP) markers. Composite interval mapping (CIM) revealed repeatedly detected QTL for DCI on C06 and C09. The estimated additive effect increased at high temperatures. Significant QTL × environment interactions (Q × E) for FLN and DCI on C06 and C09 suggest that these hotspot regions have major influences on temperature mediated curd induction. 25 % of the DH lines did not induce curds at temperatures higher than 22 °C. Applying a binary model revealed a QTL with LOD >15 on C06. Nearly all lines carrying the allele of the reliable early maturing parental line (PL) on that locus induced curds at high temperatures while only half of the DH lines carrying the allele of the unreliable PL reached the generative phase during the experiment. Large variation in LAR was observed. QTL for LAR were detected repeatedly in several environments on C01, C04 and C06. Negative correlations between LAR and DCI and QTL co-localizations on C04 and C06 suggest that LAR has also effects on development towards curd induction.

IM-19: a new flexible microporous gallium based-MOF framework with pressure- and temperature-dependent openings.

PubMed

Chaplais, Gérald; Simon-Masseron, Angélique; Porcher, Florence; Lecomte, Claude; Bazer-Bachi, Delphine; Bats, Nicolas; Patarin, Joël

2009-07-14

Five metal-organic frameworks (MOFs) based on the same three-dimensional gallium terephthalate network (IM-19) are described, and an incommensurate structure (for the as-synthesized form) as well as two remarkable guest-free polymorphs (open and closed) are highlighted.

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer).

PubMed

Drews, Anna; Strandh, Maria; Råberg, Lars; Westerdahl, Helena

2017-06-26

The Major Histocompatibility Complex (MHC) plays a central role in immunity and has been given considerable attention by evolutionary ecologists due to its associations with fitness-related traits. Songbirds have unusually high numbers of MHC class I (MHC-I) genes, but it is not known whether all are expressed and equally important for immune function. Classical MHC-I genes are highly expressed, polymorphic and present peptides to T-cells whereas non-classical MHC-I genes have lower expression, are more monomorphic and do not present peptides to T-cells. To get a better understanding of the highly duplicated MHC genes in songbirds, we studied gene expression in a phylogenetic framework in three species of sparrows (house sparrow, tree sparrow and Spanish sparrow), using high-throughput sequencing. We hypothesize that sparrows could have classical and non-classical genes, as previously indicated though never tested using gene expression. The phylogenetic analyses reveal two distinct types of MHC-I alleles among the three sparrow species, one with high and one with low level of polymorphism, thus resembling classical and non-classical genes, respectively. All individuals had both types of alleles, but there was copy number variation both within and among the sparrow species. However, the number of highly polymorphic alleles that were expressed did not vary between species, suggesting that the structural genomic variation is counterbalanced by conserved gene expression. Overall, 50% of the MHC-I alleles were expressed in sparrows. Expression of the highly polymorphic alleles was very variable, whereas the alleles with low polymorphism had uniformly low expression. Interestingly, within an individual only one or two alleles from the polymorphic genes were highly expressed, indicating that only a single copy of these is highly expressed. Taken together, the phylogenetic reconstruction and the analyses of expression suggest that sparrows have both classical and non-classical MHC-I genes, and that the evolutionary origin of these genes predate the split of the three investigated sparrow species 7 million years ago. Because only the classical MHC-I genes are involved in antigen presentation, the function of different MHC-I genes should be considered in future ecological and evolutionary studies of MHC-I in sparrows and other songbirds.

Characterization and compilation of polymorphic simple sequence repeat (SSR) markers of peanut from public database

PubMed Central

2012-01-01

Background There are several reports describing thousands of SSR markers in the peanut (Arachis hypogaea L.) genome. There is a need to integrate various research reports of peanut DNA polymorphism into a single platform. Further, because of lack of uniformity in the labeling of these markers across the publications, there is some confusion on the identities of many markers. We describe below an effort to develop a central comprehensive database of polymorphic SSR markers in peanut. Findings We compiled 1,343 SSR markers as detecting polymorphism (14.5%) within a total of 9,274 markers. Amongst all polymorphic SSRs examined, we found that AG motif (36.5%) was the most abundant followed by AAG (12.1%), AAT (10.9%), and AT (10.3%).The mean length of SSR repeats in dinucleotide SSRs was significantly longer than that in trinucleotide SSRs. Dinucleotide SSRs showed higher polymorphism frequency for genomic SSRs when compared to trinucleotide SSRs, while for EST-SSRs, the frequency of polymorphic SSRs was higher in trinucleotide SSRs than in dinucleotide SSRs. The correlation of the length of SSR and the frequency of polymorphism revealed that the frequency of polymorphism was decreased as motif repeat number increased. Conclusions The assembled polymorphic SSRs would enhance the density of the existing genetic maps of peanut, which could also be a useful source of DNA markers suitable for high-throughput QTL mapping and marker-assisted selection in peanut improvement and thus would be of value to breeders. PMID:22818284

Single-tube tetradecaplex panel of highly polymorphic microsatellite markers < 1 Mb from F8 for simplified preimplantation genetic diagnosis of hemophilia A.

PubMed

Zhao, M; Chen, M; Tan, A S C; Cheah, F S H; Mathew, J; Wong, P C; Chong, S S

2017-07-01

Essentials Preimplantation genetic diagnosis (PGD) of severe hemophilia A relies on linkage analysis. Simultaneous multi-marker screening can simplify selection of informative markers in a couple. We developed a single-tube tetradecaplex panel of polymorphic markers for hemophilia A PGD use. Informative markers can be used for linkage analysis alone or combined with mutation detection. Background It is currently not possible to perform single-cell preimplantation genetic diagnosis (PGD) to directly detect the common inversion mutations of the factor VIII (F8) gene responsible for severe hemophilia A (HEMA). As such, PGD for such inversion carriers relies on indirect analysis of linked polymorphic markers. Objectives To simplify linkage-based PGD of HEMA, we aimed to develop a panel of highly polymorphic microsatellite markers located near the F8 gene that could be simultaneously genotyped in a multiplex-PCR reaction. Methods We assessed the polymorphism of various microsatellite markers located ≤ 1 Mb from F8 in 177 female subjects. Highly polymorphic markers were selected for co-amplification with the AMELX/Y indel dimorphism in a single-tube reaction. Results Thirteen microsatellite markers located within 0.6 Mb of F8 were successfully co-amplified with AMELX/Y in a single-tube reaction. Observed heterozygosities of component markers ranged from 0.43 to 0.84, and ∼70-80% of individuals were heterozygous for ≥ 5 markers. The tetradecaplex panel successfully identified fully informative markers in a couple interested in PGD for HEMA because of an intragenic F8 point mutation, with haplotype phasing established through a carrier daughter. In-vitro fertilization (IVF)-PGD involved single-tube co-amplification of fully informative markers with AMELX/Y and the mutation-containing F8 amplicon, followed by microsatellite analysis and amplicon mutation-site minisequencing analysis. Conclusions The single-tube multiplex-PCR format of this highly polymorphic microsatellite marker panel simplifies identification and selection of informative markers for linkage-based PGD of HEMA. Informative markers can also be easily co-amplified with mutation-containing F8 amplicons for combined mutation detection and linkage analysis. © 2017 International Society on Thrombosis and Haemostasis.

Obesity-related gene ADRB2, ADRB3 and GHRL polymorphisms and the response to a weight loss diet intervention in adult women.

PubMed

Saliba, Louise F; Reis, Rodrigo S; Brownson, Ross C; Hino, Adriano A; Tureck, Luciane V; Valko, Cheryl; de Souza, Ricardo L R; Furtado-Alle, Lupe

2014-03-01

The individual response to diet may be influenced by gene polymorphisms. This study hypothesized that ADRB2 (Gln27Glu, rs1042714 and Arg16Gly, rs1042713), ADRB3 (Trp64Arg, rs4994) and GHRL (Leu72Met, rs696217) polymorphisms moderate weight loss. The study was a seven weeks dietary weight loss intervention with Brazilian adult obese women (n = 109). The body mass index (BMI) was calculated and polymorphisms in these genes were assessed by real-time PCR assays. Two-way repeated-measures ANOVA (2 × 2) were used to analyze the intervention effect between polymorphisms and BMI over the period and after stratification for age and socioeconomic status (SES). The weight loss intervention resulted in decreased BMI over the seven-week period (p < 0.001), for high and low SES (p < 0.05) and mainly for participants with 30-49 y. The intervention did not result in a statistically significant difference in weight loss between polymorphism carriers and non-carriers, and although, the ADRB2, ADRB3 and GHRL polymorphisms did not moderate weight loss, the Gln27Glu polymorphism carriers showed a lower BMI compared to non-carriers in the low SES (p = 0.018) and the 30-39 y (p = 0.036) groups, suggesting a role for this polymorphism related to BMI control.

Obesity-related gene ADRB2, ADRB3 and GHRL polymorphisms and the response to a weight loss diet intervention in adult women

PubMed Central

Saliba, Louise F.; Reis, Rodrigo S.; Brownson, Ross C.; Hino, Adriano A.; Tureck, Luciane V.; Valko, Cheryl; de Souza, Ricardo L.R.; Furtado-Alle, Lupe

2014-01-01

The individual response to diet may be influenced by gene polymorphisms. This study hypothesized that ADRB2 (Gln27Glu, rs1042714 and Arg16Gly, rs1042713), ADRB3 (Trp64Arg, rs4994) and GHRL (Leu72Met, rs696217) polymorphisms moderate weight loss. The study was a seven weeks dietary weight loss intervention with Brazilian adult obese women (n = 109). The body mass index (BMI) was calculated and polymorphisms in these genes were assessed by real-time PCR assays. Two-way repeated-measures ANOVA (2 × 2) were used to analyze the intervention effect between polymorphisms and BMI over the period and after stratification for age and socioeconomic status (SES). The weight loss intervention resulted in decreased BMI over the seven-week period (p < 0.001), for high and low SES (p < 0.05) and mainly for participants with 30–49 y. The intervention did not result in a statistically significant difference in weight loss between polymorphism carriers and non-carriers, and although, the ADRB2, ADRB3 and GHRL polymorphisms did not moderate weight loss, the Gln27Glu polymorphism carriers showed a lower BMI compared to non-carriers in the low SES (p = 0.018) and the 30–39 y (p = 0.036) groups, suggesting a role for this polymorphism related to BMI control. PMID:24688286

Single-feature polymorphism discovery in the barley transcriptome

PubMed Central

Rostoks, Nils; Borevitz, Justin O; Hedley, Peter E; Russell, Joanne; Mudie, Sharon; Morris, Jenny; Cardle, Linda; Marshall, David F; Waugh, Robbie

2005-01-01

A probe-level model for analysis of GeneChip gene-expression data is presented which identified more than 10,000 single-feature polymorphisms (SFP) between two barley genotypes. The method has good sensitivity, as 67% of known single-nucleotide polymorphisms (SNP) were called as SFPs. This method is applicable to all oligonucleotide microarray data, accounts for SNP effects in gene-expression data and represents an efficient and versatile approach for highly parallel marker identification in large genomes. PMID:15960806

Polymorphism of Trp64Arg in beta3-adrenergic receptor gene among Bolivian people in rural areas at high and low altitudes.

PubMed

Karasaki, Yuji; Kashiwazaki, Hiroshi

2004-01-01

To investigate whether population differences in food and/or lifestyle could affect the distribution frequencies of polymorphism in the gene for beta3-adrenergic receptor (beta3-AR), the frequency of Trp64Arg polymorphism was studied among Bolivian people living in rural areas of high (about 4000 m above sea level) and low (about 300 m above sea level) altitudes. Genomic DNA samples of Bolivian subjects (n=508) were amplified by polymerase chain reaction (PCR) for part of the beta3-AR gene. The amplified PCR products were digested with restriction enzyme NciI and analysed by agarose gel electrophoresis. We found no significant difference in the frequency of Arg allele in the beta3-AR gene between 331 native low-altitude Bolivian subjects (18.1%) and 177 native high-altitude Bolivian subjects (17.5%). Body mass index was not associated with Trp64Arg polymorphism among native Bolivian adults. The frequency of this allele in the complete Bolivian population (18%) was lower than that reported in Pima Indians (32%), is comparable to the Japanese (19%) and is higher than several ethnic groups, including Finns (12%) and French (4%). Our data indicate that the altitude-related lifestyle of a population has had little influence on the frequency of Trp64Arg polymorphism and obesity in Bolivian natives.

Isolation and characterization of new highly polymorphic DNA markers from the Huntington disease region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, B.; Hedrick, A.; Andrew, S.

1992-02-01

The defect causing Huntington disease (HD) has been mapped to 4p16.3, distal to the DNA marker D4S10. Subsequently, additional polymorphic markers closer to the HD gene have been isolated, which has led to the establishment of predictive testing programs for individuals at risk for HD. Approximately 17% of persons presenting to the Canadian collaborative study for predictive testing for HD have not received any modification of risk, in part because of limited informativeness of currently available DNA markers. Therefore, more highly polymorphic DNA markers are needed, which well further increase the accuracy and availability of predictive testing, specifically for familiesmore » with complex or incomplete pedigree structures. In addition, new markers are urgently needed in order to refine the breakpoints in the few known recombinant HD chromosomes, which could allow a more accurate localization of the HD gene within 4p16.3 and, therefore, accelerate the cloning of the disease gene. In this study, the authors present the identification and characterization of nine new polymorphic DNA markers, including three markers which detect highly informative multiallelic VNTR-like polymorphisms with PIC values of up to .84. These markers have been isolated from a cloned region of DNA which has been previously mapped approximately 1,000 kb from the 4p telomere.« less

Predictive Value of Gene Polymorphisms on Recurrence after the Withdrawal of Antithyroid Drugs in Patients with Graves’ Disease

PubMed Central

Liu, Jia; Fu, Jing; Duan, Yan; Wang, Guang

2017-01-01

Graves’ disease (GD) is one of the most common endocrine diseases. Antithyroid drugs (ATDs) treatment is frequently used as the first-choice therapy for GD patients in most countries due to the superiority in safety and tolerance. However, GD patients treated with ATD have a relatively high recurrence rate after drug withdrawal, which is a main limitation for ATD treatment. It is of great importance to identify some predictors of the higher recurrence risk for GD patients, which may facilitate an appropriate therapeutic approach for a given patient at the time of GD diagnosis. The genetic factor was widely believed to be an important pathogenesis for GD. Increasing studies were conducted to investigate the relationship between gene polymorphisms and the recurrence risk in GD patients. In this article, we updated the current literatures to highlight the predictive value of gene polymorphisms on recurrence risk in GD patients after ATD withdrawal. Some gene polymorphisms, such as CTLA4 rs231775, human leukocyte antigen polymorphisms (DRB1*03, DQA1*05, and DQB1*02) might be associated with the high recurrence risk in GD patients. Further prospective studies on patients of different ethnicities, especially studies with large sample sizes, and long-term follow-up, should be conducted to confirm the predictive roles of gene polymorphism. PMID:29085334

Influence of serum leptin levels and Q223R leptin receptor polymorphism on clinical characteristic of patients with rheumatoid arthritis from Western Mexico.

PubMed

Angel-Chávez, Luis I; Ruelas-Cinco, Elizabeth; Hernández-Bello, Jorge; Castro, Elena; Vázquez-Villamar, Mirna; Parra-Rojas, Isela; Brennan-Bourdon, L Michele; Muñoz-Barrios, Salvador; Guerrero-Velázquez, Celia; Muñoz-Valle, José Francisco

2018-04-01

The aim of the present study was to evaluate the possible association between the Q223R Leptin receptor (LEPR) polymorphism (A>G; rs1137101) and leptin levels in patients with rheumatoid arthritis (RA) from Western Mexico. A cross-sectional study was performed with 70 RA patients and 74 controls subject (CS). Disease activity was evaluated using DAS28 score, the Q223R LEPR polymorphism was determined by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and serum leptin levels, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factor (RF) were quantified. RA patients had significant high serum leptin levels compared with CS; leptin levels correlated strongly with body composition measures, but not with inflammatory markers, disease evolution, and activity. The genotype and allele frequencies of the Q223R LEPR polymorphism were not associated with RA. Similarly, leptin levels did not differ between Q223R LEPR genotypes. The LEPR Q223R polymorphism was not associated with RA risk in patients from Mexican population, even though high levels of serum leptin were present and these could explain the low weight observed in RA patients when they were compared to control subjects. However, the serum leptin levels did not correlate with inflammatory markers, severity and disease evolution.

CARCINOGEN METABOLISM GENES, RED MEAT AND POULTRY INTAKE, AND COLORECTAL CANCER RISK

PubMed Central

Wang, Jun; Joshi, Amit D.; Corral, Román; Siegmund, Kimberly D.; Le Marchand, Loïc; Martinez, Maria Elena; Haile, Robert W.; Ahnen, Dennis J.; Sandler, Robert S.; Lance, Peter; Stern, Mariana C.

2011-01-01

Diets high in red meat are established risk factors for colorectal cancer (CRC). Carcinogenic compounds generated during meat cooking have been implicated as causal agents. We conducted a family-based case-control study to investigate the association between polymorphisms in carcinogen metabolism genes (CYP1A2 -154A>C, CYP1B1 Leu432Val, CYP2E1 -1054C>T, GSTP1 Ile105Val, PTGS2 5UTR -765, EPHX1 Tyr113His, NAT2 Ile114Thr, NAT2 Arg197Gln and NAT2 Gly286Glu) and CRC risk. We tested for gene-environment interactions using case-only analyses (N = 577) and compared statistically significant results to those obtained using case-unaffected sibling comparisons (N = 307 sibships). Our results suggested that CYP1A2 -154A>C might modify the association between intake of red meat cooked using high temperature methods and well done on the inside and CRC risk (case-only interaction OR = 1.53; 95% CI = 1.19-1.97; p = 0.0008) and the association between intake of red meat heavily browned on the outside and rectal cancer risk (case-only interaction OR = 0.65; 95% CI = 0.48-0.86; p = 0.003). We also found that GSTP1 Ile105Val might modify the association between intake of poultry cooked with high temperature methods and CRC risk (p = 0.0035), a finding that was stronger among rectal cancer cases. Our results support a role for heterocyclic amines that form in red meat as a potential explanation for the observed association between diets high in red meat and CRC. Our findings also suggest a possible role for diets high in poultry cooked at high temperatures in CRC risk. PMID:21618522

Differentiation of “Candidatus Liberibacter asiaticus” Isolates by Variable-Number Tandem-Repeat Analysis ▿

PubMed Central

Katoh, Hiroshi; Subandiyah, Siti; Tomimura, Kenta; Okuda, Mitsuru; Su, Hong-Ji; Iwanami, Toru

2011-01-01

Four highly polymorphic simple sequence repeat (SSR) loci were selected and used to differentiate 84 Japanese isolates of “Candidatus Liberibacter asiaticus.” The Nei's measure of genetic diversity values for these four SSRs ranged from 0.60 to 0.86. The four SSR loci were also highly polymorphic in four isolates from Taiwan and 12 isolates from Indonesia. PMID:21239554

One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films.

PubMed

Giri, Gaurav; Li, Ruipeng; Smilgies, Detlef-M; Li, Er Qiang; Diao, Ying; Lenn, Kristina M; Chiu, Melanie; Lin, Debora W; Allen, Ranulfo; Reinspach, Julia; Mannsfeld, Stefan C B; Thoroddsen, Sigurdur T; Clancy, Paulette; Bao, Zhenan; Amassian, Aram

2014-04-16

A crystal's structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes.

Impact of genomic polymorphisms on the repertoire of human MHC class I-associated peptides

PubMed Central

Granados, Diana Paola; Sriranganadane, Dev; Daouda, Tariq; Zieger, Antoine; Laumont, Céline M.; Caron-Lizotte, Olivier; Boucher, Geneviève; Hardy, Marie-Pierre; Gendron, Patrick; Côté, Caroline; Lemieux, Sébastien; Thibault, Pierre; Perreault, Claude

2014-01-01

For decades, the global impact of genomic polymorphisms on the repertoire of peptides presented by major histocompatibility complex (MHC) has remained a matter of speculation. Here we present a novel approach that enables high-throughput discovery of polymorphic MHC class I-associated peptides (MIPs), which play a major role in allorecognition. On the basis of comprehensive analyses of the genomic landscape of MIPs eluted from B lymphoblasts of two MHC-identical siblings, we show that 0.5% of non-synonymous single nucleotide variations are represented in the MIP repertoire. The 34 polymorphic MIPs found in our subjects are encoded by bi-allelic loci with dominant and recessive alleles. Our analyses show that, at the population level, 12% of the MIP-coding exome is polymorphic. Our method provides fundamental insights into the relationship between the genomic self and the immune self and accelerates the discovery of polymorphic MIPs (also known as minor histocompatibility antigens). PMID:24714562

Petrogenesis of Miller Range 07273, a new type of anomalous melt breccia: Implications for impact effects on the H chondrite asteroid

NASA Astrophysics Data System (ADS)

Ruzicka, Alex M.; Hutson, Melinda; Friedrich, Jon M.; Rivers, Mark L.; Weisberg, Michael K.; Ebel, Denton S.; Ziegler, Karen; Rumble, Douglas; Dolan, Alyssa A.

2017-09-01

Miller Range 07273 is a chondritic melt breccia that contains clasts of equilibrated ordinary chondrite set in a fine-grained (<5 μm), largely crystalline, igneous matrix. Data indicate that MIL was derived from the H chondrite parent asteroid, although it has an oxygen isotope composition that approaches but falls outside of the established H group. MIL also is distinctive in having low porosity, cone-like shapes for coarse metal grains, unusual internal textures and compositions for coarse metal, a matrix composed chiefly of clinoenstatite and omphacitic pigeonite, and troilite veining most common in coarse olivine and orthopyroxene. These features can be explained by a model involving impact into a porous target that produced brief but intense heating at high pressure, a sudden pressure drop, and a slower drop in temperature. Olivine and orthopyroxene in chondrule clasts were the least melted and the most deformed, whereas matrix and troilite melted completely and crystallized to nearly strain-free minerals. Coarse metal was largely but incompletely liquefied, and matrix silicates formed by the breakdown during melting of albitic feldspar and some olivine to form pyroxene at high pressure (>3 GPa, possibly to 15-19 GPa) and temperature (>1350 °C, possibly to ≥2000 °C). The higher pressures and temperatures would have involved back-reaction of high-pressure polymorphs to pyroxene and olivine upon cooling. Silicates outside of melt matrix have compositions that were relatively unchanged owing to brief heating duration.

Genes for psychosis and creativity: a promoter polymorphism of the neuregulin 1 gene is related to creativity in people with high intellectual achievement.

PubMed

Kéri, Szabolcs

2009-09-01

Why are genetic polymorphisms related to severe mental disorders retained in the gene pool of a population? A possible answer is that these genetic variations may have a positive impact on psychological functions. Here, I show that a biologically relevant polymorphism of the promoter region of the neuregulin 1 gene (SNP8NRG243177/rs6994992) is associated with creativity in people with high intellectual and academic performance. Intriguingly, the highest creative achievements and creative-thinking scores were found in people who carried the T/T genotype, which was previously shown to be related to psychosis risk and altered prefrontal activation.

Microsatellite markers characterized in the barn owl (Tyto alba) and of high utility in other owls (Strigiformes: AVES).

PubMed

Klein, Akos; Horsburgh, Gavin J; Küpper, Clemens; Major, Agnes; Lee, Patricia L M; Hoffmann, Gyula; Mátics, Róbert; Dawson, Deborah A

2009-11-01

We have identified 15 polymorphic microsatellite loci for the barn owl (Tyto alba), five from testing published owl loci and 10 from testing non-owl loci, including loci known to be of high utility in passerines and shorebirds. All 15 loci were sequenced in barn owl, and new primer sets were designed for eight loci. The 15 polymorphic loci displayed two to 26 alleles in 56-58 barn owls. When tested in 10 other owl species (n = 1-6 individuals), between four and nine loci were polymorphic per species. These loci are suitable for studies of population structure and parentage in owls. © 2009 Blackwell Publishing Ltd.

High-temperature crystal chemistry of layered calcium borosilicates: CaBSiO4(OH) (datolite), Ca4B5Si3O15(OH)5 (`bakerite') and Ca2B2SiO7 (synthetic analogue of okayamalite)

NASA Astrophysics Data System (ADS)

Krzhizhanovskaya, Maria G.; Gorelova, L. A.; Bubnova, R. S.; Pekov, I. V.; Krivovichev, S. V.

2018-05-01

The high-temperature behaviour of three Ca borosilicates has been studied by in situ powder high-temperature X-ray diffraction (HTXRD), differential scanning calorimetry and thermogravimetry in the temperature range 30-900 °C for natural samples of datolite, CaBSiO4(OH), and `bakerite', Ca4B5Si3O15(OH)5, and a synthetic analogue of okayamalite, Ca2B2SiO7. The latter was obtained by heating datolite at 800 °C for 5 h. Datolite and bakerite start to dehydroxylate above 700 and 500 °C, respectively, and decompose fully to form a high-temperature modification of okayamalite, HT-Ca2B2SiO7, and wollastonite, CaSiO3 at about 730 °C. Above 900 °C, HT-okayamalite decomposes with the formation of wollastonite, CaSiO3, and metaborate CaB2O4. The latter melts at about 990 °C. Above 1000 °C, only the existence of wollastonite, CaSiO3 and cristobalite, SiO2 was observed. According to the HTXRD data, in the temperature range 30-500 °C, datolite and `bakerite' demonstrate very similar and relatively low volumetric thermal expansion: α v = 29 and 27 × 10-6 °C-1, respectively. A high thermal expansion anisotropy ( α max/ α min 3) is caused by both the layered character of the crystal structures and the shear deformations of their monoclinic unit cells. The direction of maximum expansion is intermediate between the normal direction to the layers and the ( a + c) vector. A possible transformation mechanism from the datolite to the okayamalite structure topology is proposed from geometrical considerations. The synthetic analogue of okayamalite, Ca2B2SiO7, undergoes a reversible polymorphic transition at about 550 °C with a decrease in symmetry from tetragonal to orthorhombic. The crystal structure of the high-temperature (HT) modification of okayamalite was solved from the powder-diffraction data [900 °C: P21212, a = 7.3361(4), b = 7.1987(4), c = 4.8619(4) Å, V = 256.76(3) Å3, R wp = 6.61, R Bragg = 2.68%].

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avdontceva, Margarita S.; Zolotarev, Andrey A.; Krivovichev, Sergey V., E-mail: s.krivovichev@spbu.ru

High-temperature phase transition of synthetic kogarkoite, Na{sub 3}SO{sub 4}F, has been studied by high-temperature X-ray powder and single-crystal diffraction. The temperature of the phase transition can be estimated as 112.5±12.5 °C. The low-temperature phase, α-Na{sub 3}SO{sub 4}F, at 293 K, is monoclinic, P2{sub 1}/m, a=18.065(3), b=6.958(1), c=11.446(1) Å, β=107.711(1)°, Z=12. The structure contains thirteen symmetrically independent Na sites with coordination numbers varying from 6 to 8, and six independent S sites. The high-temperature β-phase at 423 K is rhombohedral, R-3m, a=6.94(1), c=24.58(4) Å, Z=9. The crystal structure of both polymorphs of Na{sub 3}SO{sub 4}F can be described as a 9Rmore » antiperovskite polytype based upon triplets of face-sharing [FNa{sub 6}] octahedra linked into a three-dimensional framework by sharing corners. In the α-modification, the SO{sub 4} tetrahedra are completely ordered and located in the framework cavities. In the β-modification, there are only two symmetrically independent Na atoms in the structure. The main difference between the structures of the α- and β-phases is the degree of ordering of the SO{sub 4} tetrahedra: in the α-modification, they are completely ordered, whereas, in the β-modification, the complete disorder is observed, which is manifested in a number of low-occupied O sites around fully occupied S sites. The phase transition is therefore has an order–disorder character and is associated with the decrease of structural complexity measured as an information content per unit cell [577.528 bits for the low- (α) and 154.830 bits for the high- (β) temperature modifications]. - Graphical abstract: High-temperature phase transition of synthetic kogarkoite, Na{sub 3}SO{sub 4}F, revealed the existence of the monoclinic-to-rhombohedral phase transition at 112.5±12.5 °C. The phase transition has an order–disorder character and is associated with the decrease of structural complexity. - Highlights: • Phase transition in Na{sub 3}SO{sub 4}F (kogarkoite) has an order–disorder character. • Antiperovskite framework of F-centered octahedra has a high stability. • Information-based structural complexity decreases across the phase transition.« less

Microscopic origin of entropy-driven polymorphism in hybrid organic-inorganic perovskite materials

NASA Astrophysics Data System (ADS)

Butler, Keith T.; Svane, Katrine; Kieslich, Gregor; Cheetham, Anthony K.; Walsh, Aron

2016-11-01

Entropy is a critical, but often overlooked, factor in determining the relative stabilities of crystal phases. The importance of entropy is most pronounced in softer materials, where small changes in free energy can drive phase transitions, which has recently been demonstrated in the case of organic-inorganic hybrid-formate perovskites. In this Rapid Communication we demonstrate the interplay between composition and crystal structure that is responsible for the particularly pronounced role of entropy in determining polymorphism in hybrid organic-inorganic materials. Using ab initio based lattice dynamics, we probe the origins and effects of vibrational entropy of four archetype perovskite (A B X3 ) structures. We consider an inorganic material (SrTiO3), an A -site hybrid-halide material (CH3NH3) PbI3 , a X -site hybrid material KSr (BH4)3 , and a mixed A - and X -site hybrid-formate material (N2H5) Zn (HCO2)3 , comparing the differences in entropy between two common polymorphs. The results demonstrate the importance of low-frequency intermolecular modes in determining the phase stability in these materials. The understanding gained allows us to propose a general principle for the relative stability of different polymorphs of hybrid materials as temperature is increased.

Numerical modeling of polymorphic transformation of oleic acid via near-infrared spectroscopy and factor analysis.

PubMed

Liu, Ling; Cheng, Yuliang; Sun, Xiulan; Pi, Fuwei

2018-05-15

Near-infrared (NIR) spectroscopy as a tool for direct and quantitatively screening the minute polymorphic transitions of bioactive fatty acids was assessed basing on a thermal heating process of oleic acid. Temperature-dependent NIR spectral profiles indicate that dynamical variances of COOH group dominate its γ → α phase transition, while the transition from active α to β phase mainly relates to the conformational transfer of acyl chain. Through operating multivariate curve resolution-alternating least squares with factor analysis, instantaneous contribution of each active polymorph during the transition process was illustrated for displaying the progressive evolutions of functional groups. Calculated contributions reveal that the α phase of oleic acid initially is present at around -18 °C, but sharply grows up around -2.2 °C from the transformation of γ phase and finally disappears at the melting point. On the other hand, the β phase of oleic acid is sole self-generation after melt even it embryonically appears at -2.2 °C. Such mathematical approach based on NIR spectroscopy and factor analysis calculation provides a volatile strategy in quantitatively exploring the transition processes of bioactive fatty acids; meanwhile, it maintains promising possibility for instantaneous quantifying each active polymorph of lipid materials. Copyright © 2018 Elsevier B.V. All rights reserved.

Numerical modeling of polymorphic transformation of oleic acid via near-infrared spectroscopy and factor analysis

NASA Astrophysics Data System (ADS)

Liu, Ling; Cheng, Yuliang; Sun, Xiulan; Pi, Fuwei

2018-05-01

Near-infrared (NIR) spectroscopy as a tool for direct and quantitatively screening the minute polymorphic transitions of bioactive fatty acids was assessed basing on a thermal heating process of oleic acid. Temperature-dependent NIR spectral profiles indicate that dynamical variances of COOH group dominate its γ → α phase transition, while the transition from active α to β phase mainly relates to the conformational transfer of acyl chain. Through operating multivariate curve resolution-alternating least squares with factor analysis, instantaneous contribution of each active polymorph during the transition process was illustrated for displaying the progressive evolutions of functional groups. Calculated contributions reveal that the α phase of oleic acid initially is present at around -18 °C, but sharply grows up around -2.2 °C from the transformation of γ phase and finally disappears at the melting point. On the other hand, the β phase of oleic acid is sole self-generation after melt even it embryonically appears at -2.2 °C. Such mathematical approach based on NIR spectroscopy and factor analysis calculation provides a volatile strategy in quantitatively exploring the transition processes of bioactive fatty acids; meanwhile, it maintains promising possibility for instantaneous quantifying each active polymorph of lipid materials.

DNA methylation polymorphism in flue-cured tobacco and candidate markers for tobacco mosaic virus resistance.

PubMed

Zhao, Jie-hong; Zhang, Ji-shun; Wang, Yi; Wang, Ren-gang; Wu, Chun; Fan, Long-jiang; Ren, Xue-liang

2011-11-01

DNA methylation plays an important role in the epigenetic regulation of gene expression during plant growth, development, and polyploidization. However, there is still no distinct evidence in tobacco regarding the distribution of the methylation pattern and whether it contributes to qualitative characteristics. We studied the levels and patterns of methylation polymorphism at CCGG sites in 48 accessions of allotetraploid flue-cured tobacco, Nicotiana tabacum, using a methylation-sensitive amplified polymorphism (MSAP) technique. The results showed that methylation existed at a high level among tobacco accessions, among which 49.3% sites were methylated and 69.9% allelic sites were polymorphic. A cluster analysis revealed distinct patterns of geography-specific groups. In addition, three polymorphic sites significantly related to tobacco mosaic virus (TMV) resistance were explored. This suggests that tobacco breeders should pay more attention to epigenetic traits.

A Matter of Life or Death: Untangling the Coupled Roles of Behavior, Microclimate and Physiological Polymorphism in Governing Vulnerability of Intertidal Snails to Heat Stress

NASA Astrophysics Data System (ADS)

Dong, Y.; Li, X.; Choi, F.; Willams, G.; Somero, G. N.; Helmuth, B.

2016-12-01

Changing patterns of species' biogeographic distributions are driven by cumulative effects of much smaller scale processes. Specifically, vulnerability of animals to thermal stress is the result of physiological sensitivities to body temperature (Tb), local microclimatic conditions, and abilities to anticipate extreme conditions and move to cooler refugia. These variables have rarely been quantified simultaneously over large geographic scales. We analyzed the thermal tolerances of three species of rocky intertidal snails from eight sites spanning 11.5 degrees of latitude along the Chinese coast. Using a biophysical model, we estimated potential Tb in sun-exposed and shaded microhabitats for all species at these sites for 30 years. We then compared maximum predicted Tb against the temperatures at which cardiac function was impaired (Arrhenius Break Temperatures, ABT) and lethal limits were reached (cardiac Flat Line Temperatures, FLT) to calculate thermal Safety Margins (TSM) for normal physiological function (TSMABT) and heat death (TSMFLT). Regular exceedance of FLT in sun-exposed microhabitats was predicted for only one site in the middle of the geographic gradient. However, ABT was exceeded at sun-exposed microhabitats in most sites, suggesting significant physiological impairment for snails that fail to move into the shade. An autocorrelation analysis of snail Tb showed that predictability of extreme temperatures was lowest at the hottest sites, an indication that reliance on behavioral thermoregulation may be a risky strategy. Observed large differences in ABT and FLT among conspecifics emphasize the critical role of physiological polymorphisms in governing the vulnerability of populations to heat stress.

How social learning adds up to a culture: from birdsong to human public opinion

PubMed Central

Feher, Olga; Fimiarz, Daniel; Conley, Dalton

2017-01-01

ABSTRACT Distributed social learning may occur at many temporal and spatial scales, but it rarely adds up to a stable culture. Cultures vary in stability and diversity (polymorphism), ranging from chaotic or drifting cultures, through cumulative polymorphic cultures, to stable monolithic cultures with high conformity levels. What features can sustain polymorphism, preventing cultures from collapsing into either chaotic or highly conforming states? We investigate this question by integrating studies across two quite separate disciplines: the emergence of song cultures in birds, and the spread of public opinion and social conventions in humans. In songbirds, the learning process has been studied in great detail, while in human studies the structure of social networks has been experimentally manipulated on large scales. In both cases, the manner in which communication signals are compressed and filtered – either during learning or while traveling through the social network – can affect culture polymorphism and stability. We suggest a simple mechanism of a shifting balance between converging and diverging social forces to explain these effects. Understanding social forces that shape cultural evolution might be useful for designing agile communication systems, which are stable and polymorphic enough to promote gradual changes in institutional behavior. PMID:28057835

Frequency of genetic polymorphisms of PXR gene in the Brazilian population.

PubMed

Moreira, Ricardo P P; Jorge, Alexander A L; Mendonca, Berenice B; Bachega, Tânia A S S

2011-01-01

PXR polymorphisms have been implicated in modulating CYP3A4 and PXR expression, potentially accounting for interindividual differences in drug metabolism. The prevalence of PXR polymorphisms varies among ethnic groups and data on the allelic distribution in the highly mixed Brazilian population is lacking. The aim of this study was to analyze genetic variations in the PXR gene in Brazilians and to compare the results to other ethnic groups. DNA samples from 117 healthy Brazilians underwent PCR amplification and sequencing. Eleven polymorphisms were identified, 3 of which are highly associated with differences in CYP3A4 expression. We also identified 1 new synonymous variant in 1.3% of the alleles. Among the functional polymorphisms, -25913 C>T and -6994T>C occurred at a higher frequency comparedtothe Africanalleles (p < 0.05) but at a lower frequency compared to Caucasian alleles. The 8055 C>T allele was found at a similar frequency to those described in Caucasians and Africans (p > 0.05). We observed that functional variants of the PXR were frequent in our sample of the Brazilian population. Our results suggest that PXR gene variants may be of interest in pharmacogenetic studies involving Brazilians.

Polymorphism and disorder in caffeine: Dielectric investigation of molecular mobilities

NASA Astrophysics Data System (ADS)

Descamps, M.; Decroix, A. A.

2014-12-01

Using dielectric relaxation data we have characterized the molecular mobilities of caffeine both in phase I (stable and metastable) and in phase II. In phase I effects of sublimation and phase transformation kinetics were carefully considered. In plane rotational motions were followed on a wide temperature range. A noticeable antiferroelectric short range order developing at the approach of the glass-like transition is characterized. Condition for occurrence of a critical-like behaviour is discussed. At high temperature the emergence of an additional ultra slow relaxation process is highlighted. Possible molecular mechanisms are proposed for both processes. In phase II the existence of a less intense relaxation process is confirmed. Close similarity with the main process developing in phase I hints at a common origin of the dipolar motions. Careful consideration of recent structure determinations leads to suggest that this process is associated to similar molecular in plane rotations but developing at the surface of crystalline samples. Lower cooperativity at the surface is reflected in the smaller activation entropy of the relaxation.

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak

2005-07-01

Explosives formulations with Reduced- Sensitivity RDX showed reduced shock sensitivity using NOL Large Scale Gap Test, compared with similar formulations using normal RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light to the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. SIRDX, a form of Reduced- Sensitivity RDX, was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transformed IR (FTIR). The pressure dependence of the Raman mode frequencies of SIRDX was determined and compared with that of normal RDX. The behavior of SIRDX near the pressure at which normal RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph will be presented. Implications to the reduction in sensitivity will be discussed.

Large Electrocaloric Effect in Lead-Free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics Prepared via Citrate Route

PubMed Central

Shi, Jing; Zhu, Rongfeng; Liu, Xing; Yuan, Ningyi; Ding, Jianning; Luo, Haosu

2017-01-01

The 1 wt % Li-doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT-Li) ceramics prepared by the citrate method exhibit improved phase purity, densification and electrical properties, which provide prospective possibility to develop high-performance electrocaloric materials. The electrocaloric effect was evaluated by phenomenological method, and the BCZT-Li ceramics present large electrocaloric temperature change ∆T, especially large electrocaloric responsibility ξ = ∆Tmax/∆Emax, which can be comparable to the largest values reported in the lead-free piezoelectric ceramics. The excellent electrocaloric effect is considered as correlating with the coexistence of polymorphic ferroelectric phases, which are detected by the Raman spectroscopy. The large ξ value accompanied by decreased Curie temperature (around 73 °C) of the BCZT-Li ceramics prepared by the citrate method presents potential applications as the next-generation solid-state cooling devices. PMID:28927004

Large Electrocaloric Effect in Lead-Free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O₃ Ceramics Prepared via Citrate Route.

PubMed

Shi, Jing; Zhu, Rongfeng; Liu, Xing; Fang, Bijun; Yuan, Ningyi; Ding, Jianning; Luo, Haosu

2017-09-18

The 1 wt % Li-doped (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O₃ (BCZT-Li) ceramics prepared by the citrate method exhibit improved phase purity, densification and electrical properties, which provide prospective possibility to develop high-performance electrocaloric materials. The electrocaloric effect was evaluated by phenomenological method, and the BCZT-Li ceramics present large electrocaloric temperature change ∆ T , especially large electrocaloric responsibility ξ = ∆ T max /∆ E max , which can be comparable to the largest values reported in the lead-free piezoelectric ceramics. The excellent electrocaloric effect is considered as correlating with the coexistence of polymorphic ferroelectric phases, which are detected by the Raman spectroscopy. The large ξ value accompanied by decreased Curie temperature (around 73 °C) of the BCZT-Li ceramics prepared by the citrate method presents potential applications as the next-generation solid-state cooling devices.

Influence of Space Flight Factors on the Genetic Properties of Streptomyces Lividans 66 (PIJ702)

NASA Technical Reports Server (NTRS)

Tabakov, V. Yu.; Voeikova, T. A.; Tairbekov, M. G.; Goins, T. L.; Martinson, V. G.; Pyle, B. H.

2006-01-01

Gram-positive Streptomyces bacteria display genetic instability in response to external factors. Strain S. lividans 66 harbors the multicopy plasmid pIJ702 with selective and differential marker genes for antibiotic thiostrepton resistance and melanin production. Culture plates of modified ISP agar medium with and without thiostrepton were flown on Foton-M2. Suboptimal flight temperatures, which were simulated for asynchronous ground controls, resulted in slow growth and failure to differentiate and sporulate. Flight samples and asynchronous controls showed a high frequency of failing to express plasmid markers compared to laboratory controls. This was associated with loss of plasmid DNA and likely resulted from suboptimal temperatures for flight cultures and controls. Neither restriction fragment length polymorphism, nor polymerase chain reaction amplification coupled with denaturing gradient gel electrophoresis, revealed differences between pIJ702 DNA from flight vs. control clones. Mutations of the plasmid marker genes resulting from specific spaceflight factors, e.g., microgravity and radiation, were not detected.

De-vitrification of nanoscale phase-separated amorphous thin films in the immiscible copper-niobium system

NASA Astrophysics Data System (ADS)

Puthucode, A.; Devaraj, A.; Nag, S.; Bose, S.; Ayyub, P.; Kaufman, M. J.; Banerjee, R.

2014-05-01

Copper and niobium are mutually immiscible in the solid state and exhibit a large positive enthalpy of mixing in the liquid state. Using vapour quenching via magnetron co-sputter deposition, far-from equilibrium amorphous Cu-Nb films have been deposited which exhibit a nanoscale phase separation. Annealing these amorphous films at low temperatures (~200 °C) initiates crystallization via the nucleation and growth of primary nanocrystals of a face-centred cubic Cu-rich phase separated by the amorphous matrix. Interestingly, subsequent annealing at a higher temperature (>300 °C) leads to the polymorphic nucleation and growth of large spherulitic grains of a body-centred cubic Nb-rich phase within the retained amorphous matrix of the partially crystallized film. This sequential two-stage crystallization process has been investigated in detail by combining transmission electron microscopy [TEM] (including high-resolution TEM) and atom probe tomography studies. These results provide new insights into the crystallization behaviour of such unusual far-from equilibrium phase-separated metallic glasses in immiscible systems.

Influence of oxidation temperature on the oxide scale formation of NiCoCrAl coatings

NASA Astrophysics Data System (ADS)

Sugiarti, E.; Zaini, K. A.; Sundawa, R.; Wang, Y.; Ohnuki, S.; Hayashi, S.

2017-04-01

Intermetalic coatings of NiCoCrAl have been successfully developed on low carbon steel substrate to improve oxidation resistance in extreme environments. The influence of oxidation temperature on the oxide scale formation was studied in the temperature range of 600-1000 °C. The measurements were made in air under isothermal oxidation test for 100 h. The surface morphology showed that a cauliflower like structure developed entire the oxide scale of sample oxidized at 800 °C and 1000 °C, while partly distributed on the surface of sample oxidized at 600 °C. The XRD analysis identified Cr2O3 phase predominantly formed on the oxidized sample at 600 °C and meta-stable Al2O3 with several polymorphs crystalline structures: η, δ, θ, κ, and α-Al2O3 at relatively high temperatures, i.e. 800 °C and 1000 °C. A Cross-sectional microstructure showed that complex and porous structures formed on the top surface of 600 °C and 1000 °C samples. In contrast, a very thin oxide scale formed on 800 °C oxidized samples and it appeared to act as a diffusion barrier of oxygen to diffuse inward, hence could increase in the service life of carbon steel substrate.

The evaluation of physical properties of injection molded systems based on poly(ethylene oxide) (PEO).

PubMed

Pajander, Jari; Rensonnet, Alexia; Hietala, Sami; Rantanen, Jukka; Baldursdottir, Stefania

2017-02-25

The effect of product design parameters on the formation and properties of an injection molded solid dosage form consisting of poly(ethylene oxide)s (PEO) and two different active pharmaceutical ingredients (APIs) was studied. The product design parameters explored were melting temperature and the duration of melting, API loading degree and the molecular weight (M w ) of PEO. The solid form composition of the model APIs, theophylline and carbamazepine, was of specific interest, and its possible impact on the in vitro drug release behavior. M w of PEO had the greatest impact on the release rate of both APIs. High M w resulted in slower API release rate. Process temperature had two-fold effect with PEO 300,000g/mol. Firstly, higher process temperature transformed the crystalline part of the polymer into metastable folded form (more folded crystalline regions) and less into the more stable extended form (more extended crystalline regions), which lead to enhanced theophylline release rate. Secondly, the higher process temperature seemed to induce carbamazepine polymorphic transformation from p-monoclinic form III (carbamazepine (M)) into trigonal form II (carbamazepine (T)). The results indicated that the actual content of carbamazepine (T) affected drug release behavior more than the magnitude of transformation. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bugaris, Daniel E.; Malliakas, Christos D.; Han, Fei

A new polymorph of the RE 2Ru 3Ge 5 (RE = Pr, Sm, Dy) compounds has been grown as single crystals via an indium flux. These compounds crystallize in tetragonal space group P4/mnc with the Sc 2Fe 3Si 5-type structure, having lattice parameters a = 11.020(2) Å and c = 5.853(1) Å for RE = Pr, a = 10.982(2) Å and c = 5.777(1) Å for RE = Sm, and a = 10.927(2) Å and c = 5.697(1) Å for RE = Dy. These materials exhibit a structural transition at low temperature, which is attributed to an apparent charge densitymore » wave (CDW). Both the high-temperature average crystal structure and the low-temperature incommensurately modulated crystal structure (for Sm 2Ru 3Ge 5 as a representative) have been solved. The charge density wave order is manifested by periodic distortions of the onedimensional zigzag Ge chains. From X-ray diffraction, charge transport (electrical resistivity, Hall effect, magnetoresistance), magnetic measurements, and heat capacity, the ordering temperatures (T CDW) observed in the Pr and Sm analogues are ~200 and ~175 K, respectively. The charge transport measurement results indicate an electronic state transition happening simultaneously with the CDW transition. X-ray absorption near-edge spectroscopy (XANES) and electronic band structure results are also reported.« less

Study of the role of tumor necrosis factor-α (-308 G/A) and interleukin-10 (-1082 G/A) polymorphisms as potential risk factors to acute kidney injury in patients with severe sepsis using high-resolution melting curve analysis.

PubMed

Hashad, Doaa I; Elsayed, Eman T; Helmy, Tamer A; Elawady, Samier M

2017-11-01

Septic acute kidney injury (AKI) is a prevalent complication in intensive care units with an increased incidence of complications. The aim of the present study was to assess the use of high-resolution melting curve (HRM) analysis in investigating whether the genetic polymorphisms; -308 G/A of tumor necrosis factor-α (TNF-α), and -1082 G /A of Interleukin-10 (IL-10) genes may predispose patients diagnosed with severe sepsis to the development of AKI. One hundred and fifty patients with severe sepsis participated in the present study; only sixty-six developed AKI. Both polymorphisms were studied using HRM analysis. The low producer genotype of both studied polymorphism of TNF-α and IL-10 genes was associated with AKI. Using logistic regression analysis, the low producer genotypes remained an independent risk factor for AKI. A statistically significant difference was detected between both studied groups as regards the low producer genotype in both TNF-α (-308 G/A) and interleukin-10 (IL-10) (-1082 G/A) polymorphisms being prevalent in patients developing AKI. Principle conclusions: The low producer genotypes of both TNF-α (-308 G/A) and IL-10 (-1082 G/A) polymorphisms could be considered a risk factor for the development of AKI in critically ill patients with severe sepsis, thus management technique implemented for this category should be modulated rescuing this sector of patients from the grave deterioration to acute kidney injury. Using HRM for genotyping proved to be a highly efficient, simple, cost-effective genotyping technique that is most appropriate for the routine study of large-scale samples.

Ab initio thermodynamics and seismic properties of MgSiO3 polymorphs at mantle transition zone conditions: the geodynamic role of non-olivine phases

NASA Astrophysics Data System (ADS)

Belmonte, Donato; Ottonello, Giulio Armando; Vetuschi Zuccolini, Marino

2014-05-01

MgSiO3 polymorphs with the garnet, pyroxene and ilmenite structure play a key role in controlling phase equilibria and seismic velocity gradients in the mantle transition zone (440-660 km). Despite the relative abundance of structural and thermoelastic informations, thermodynamic data are still poorly constrained and their extrapolation at high pressure and temperature conditions is affected by large uncertainties. In this work, ab initio calculations of the thermodynamic properties of MgSiO3 polymorphs stable at MTZ conditions (tetragonal majorite, Mj; akimotoite, Ak; HP-clinoenstatite, HPCEn) have been carried out with the hybrid B3LYP density functional method. The static and vibrational features of these minerals (equation of state, elastic constants, seismic velocities and anisotropy, IR and Raman spectra, mode Grüneisen parameters) have been fully characterized in a broad range of P-T conditions. The vibrational density of states (vDOS) have been reproduced in the framework of quasi-harmonic approximation through a full phonon dispersion calculation or, alternatively, a modified Kieffer's model splitting the acoustic and optic modes contribution to the thermodynamic functions. The calculated heat capacities are in good agreement with the relatively few calorimetric investigations made so far on these minerals in the low- to medium-T range. However, physical unsoundness may affect the high-temperature extrapolation of calorimetric results, so that the use in phase equilibria calculation deserves great care. The calculated Gibbs free energies allow to define phase transition boundaries in the MgSiO3 phase diagram and locate the majorite-akimotite-perovskite triple point at P = 21.09 ± 0.13 GPa and T = 2247 ± 31 K. The effect of partial structural disorder in majorite, assessed via an interchange enthalpy (ΔHint = 15 kJ/mol) and configurational entropy [Sconf = 1.9 J/(mol×K)] contribution, must be taken into account to accurately reproduce the Mj-Ak-Pv triple point. The predicted Clapeyron slopes of the phase boundaries Mj-Pv, Mj-Ak, Ak-Pv and HPCEn-Mj turn out to be 2.2, 8.3, -4.0 and -3.6 MPa/K, respectively, in good agreement with experimental observations and thermodynamic optimizations as well. The geophysical implications concerning the role of non-olivine mineral phases in mantle dynamics, deep seismic discontinuities, density change and slab stagnation at 660 km depth are briefly outlined and discussed.

[Polymorphism in the regulatory part of the cholesterol 7 alpha hydroxylase gene in children with high and low levels of cholesterol].

PubMed

Hubácek, J A; Pistulková, H; Skodová, Z; Lánská, V; Poledne, R

2003-01-01

High plasma cholesterol is one of the risk factors of atherosclerosis. Both environmental (diet, physic activity) and genetic factors have been concerned in the development of hypercholesterolemia. Cholesterol 7 alpha hydroxylase (CYP-7A1) is a key enzyme in the bile acid synthesis and it plays an important role in cholesterol catabolism. The aim of the study was to establish the role of A-204-->C polymorphism in CYP-7A1 gene in plasma lipid determination in children. Using PCR and restriction analysis (BsaI) we have measured A-204-->C polymorphism in CYP-7A1 gene in two groups of children selected from opposite ends of the cholesterol distribution curve of 2000 children. Eighty-two children in high- (HCG) and eighty-six children in low- (LCG) cholesterolemic groups participated in the study. No significant difference was found in the frequencies of the genotypes or alleles of the A-204-->C polymorphism in the CYP-7A1 gene between HCG and LCG. In HCG, C/C-204 homozygotes have the highest and A/A homozygotes the lowest levels of LDL-cholesterol (4.21 +/- 0.68 mmol/l vers. 3.69 +/- 0.60 mmol/l, p < 0.05). No associations between lipid parameters and genotypes within the LCG group were found. The A-204-->C polymorphism in the gene for CYP-7A1 is not the major determinant of plasma lipid levels in childhood. Its impact is expressed only on high cholesterol background.

The UCP2 -866G/A, Ala55Val and UCP3 -55C/T polymorphisms are associated with premature coronary artery disease and cardiovascular risk factors in Mexican population.

PubMed

Gamboa, Ricardo; Huesca-Gómez, Claudia; López-Pérez, Vanessa; Posadas-Sánchez, Rosalinda; Cardoso-Saldaña, Guillermo; Medina-Urrutia, Aida; Juárez-Rojas, Juan Gabriel; Soto, María Elena; Posadas-Romero, Carlos; Vargas-Alarcón, Gilberto

2018-05-21

We examined the role of UCP gene polymorphisms as susceptibility markers for premature coronary artery disease (pCAD). The UCP2 Ala55Val (C/T rs660339), UCP2 -866G/A (rs659366), and UCP3 -55C/T (rs1800849) polymorphisms were genotyped in 948 patients with pCAD, and 763 controls. The distribution of the UCP2 A55V (C/T rs660339) and UCP3 -55 (rs1800849) was similar in patients and controls. However, under a recessive model, the UCP2 -866 (rs659366) A allele was associated with increased risk of developing pCAD (OR = 1.43, Pc = 0.003). On the other hand, patients with pCAD and UCP2 A55V (rs660339) TT showed high levels of visceral abdominal fat (VAF) (Pc = 0.002), low levels of subcutaneous abdominal fat (SAF) (Pc = 0.001) and high VAT/SAT ratio (Pc < 0.001). Also, patients with UCP2 -866 (rs659366) AA showed increased levels of VAF (Pc = 0.003), low levels of SAF (Pc = 0.001) and a high VAT/SAT ratio (Pc = 0.002), whereas patients with the UCP3 -55 (rs1800849) TT presented high levels of VAF (Pc = 0.002). The results suggest the association of the UCP2 -866 (rs659366) polymorphism with risk of developing pCAD. Some polymorphisms were associated with abdominal fat levels and cardiovascular risk factors.

Effects of mannose-binding lectin polymorphisms on irinotecan-induced febrile neutropenia.

PubMed

van der Bol, Jessica M; de Jong, Floris A; van Schaik, Ron H; Sparreboom, Alex; van Fessem, Marianne A; van de Geijn, Fleur E; van Daele, Paul L; Verweij, Jaap; Sleijfer, Stefan; Mathijssen, Ron H

2010-01-01

Mannose-binding lectin (MBL) is important in the innate immune response. MBL2 gene polymorphisms affect MBL expression, and genotypes yielding low MBL levels have been associated with an elevated risk for infections in hematological cancer patients undergoing chemotherapy. However, these reported associations are inconsistent, and data on patients with solid tumors are lacking. Here, we investigated the effects of MBL2 genotypes on irinotecan-induced febrile neutropenia in patients with solid tumors. Irinotecan-treated patients were genotyped for the MBL2 gene. Two promoter (-550 H/L and -221 X/Y) and three exon polymorphisms (52 A/D, 54 A/B, and 57 A/C) were determined, together with known risk factors for irinotecan-induced toxicity. Neutropenia and febrile neutropenia were recorded during the first course. Of the 133 patients, 28% experienced severe neutropenia and 10% experienced febrile neutropenia. No associations were found between exon polymorphisms and febrile neutropenia. However, patients with the H/H promoter genotype, associated with high MBL levels, experienced significantly more febrile neutropenia than patients with the H/L and L/L genotypes (20% versus 13% versus 5%). Moreover, patients with the HYA haplotype encountered significantly more febrile neutropenia than patients without this high MBL-producing haplotype (16% versus 4%). In the subgroup with wild-type exon polymorphisms (A/A), patients with the high MBL promoter phenotype had the highest incidence of febrile neutropenia, regardless of known risk factors. Patients with high MBL2 promoter genotypes and haplotypes seem more at risk for developing febrile neutropenia. If confirmed, these preliminary findings may contribute to more individualized approaches of irinotecan treatment.

Interlayer Communication in Aurivillius Vanadate to Enable Defect Structures and Charge Ordering.

PubMed

Zhang, Yaoqing; Yamamoto, Takafumi; Green, Mark A; Kageyama, Hiroshi; Ueda, Yutaka

2015-11-16

The fluorite-like [Bi2O2](2+) layer is a fundamental building unit in a great variety of layered compounds. Here in this contribution, we presented a comprehensive study on an unusual Aurivillius phase Bi3.6V2O10 with respect to its defect chemistry and polymorphism control as well as implications for fast oxide ion transport at lower temperatures. The bismuth oxide layer in Bi4V2O11 is found to tolerate a large number of Bi vacancies without breaking the high temperature prototype I4/mmm structure (γ-phase). On cooling, an orthorhombic distortion occurs to the γ-phase, giving rise to a different type of phase (B-phase) in the intermediate temperature region. Cooling to room temperature causes a further transition to an oxygen-vacancy ordered A-phase, which is accompanied by the charge ordering of V(4+) and V(5+) cations, providing magnetic (d(1)) and nonmagnetic (d(0)) chains along the a axis. This is a novel charge ordering transition in terms of the concomitant change of oxygen coordination. Interestingly, upon quenching, both the γ- and B-phase can be kinetically trapped, enabling the structural probing of the two phases at ambient temperature. Driven by the thermodynamic forces, the oxide anion in the γ-phase undergoes an interlayer diffusion process to reshuffle the compositions of both Bi-O and V-O layers.

Application of virtual phase-shifting speckle-interferometry for detection of polymorphism in the Chlamydia trachomatis omp1 gene

NASA Astrophysics Data System (ADS)

Feodorova, Valentina A.; Saltykov, Yury V.; Zaytsev, Sergey S.; Ulyanov, Sergey S.; Ulianova, Onega V.

2018-04-01

Method of phase-shifting speckle-interferometry has been used as a new tool with high potency for modern bioinformatics. Virtual phase-shifting speckle-interferometry has been applied for detection of polymorphism in the of Chlamydia trachomatis omp1 gene. It has been shown, that suggested method is very sensitive to natural genetic mutations as single nucleotide polymorphism (SNP). Effectiveness of proposed method has been compared with effectiveness of the newest bioinformatic tools, based on nucleotide sequence alignment.

Microstructural study of the polymorphic transformation in pentacene thin films.

PubMed

Murakami, Yosuke; Tomiya, Shigetaka; Koshitani, Naoki; Kudo, Yoshihiro; Satori, Kotaro; Itabashi, Masao; Kobayashi, Norihito; Nomoto, Kazumasa

2009-10-02

We have observed, by high-resolution cross-sectional transmission electron microscopy, the first direct evidence of polymorphic transformation in pentacene thin films deposited on silicon oxide substrates. Polymorphic transformation from the thin-film phase to the bulk phase occurred preferentially near polycrystalline grain boundaries, which exhibit concave surfaces. This process is thought to be driven by compressive stress caused by the grain boundaries. In addition to this stress, lattice mismatch between the two phases also results in structural defect formation.

The candidate histocompatibility locus of a Basal chordate encodes two highly polymorphic proteins.

PubMed

Nydam, Marie L; Netuschil, Nikolai; Sanders, Erin; Langenbacher, Adam; Lewis, Daniel D; Taketa, Daryl A; Marimuthu, Arumugapradeep; Gracey, Andrew Y; De Tomaso, Anthony W

2013-01-01

The basal chordate Botryllus schlosseri undergoes a natural transplantation reaction governed by a single, highly polymorphic locus called the fuhc. Our initial characterization of this locus suggested it encoded a single gene alternatively spliced into two transcripts: a 555 amino acid-secreted form containing the first half of the gene, and a full-length, 1008 amino acid transmembrane form, with polymorphisms throughout the ectodomain determining outcome. We have now found that the locus encodes two highly polymorphic genes which are separated by a 227 bp intergenic region: first, the secreted form as previously described, and a second gene encoding a 531 amino acid membrane-bound gene containing three extracellular immunoglobulin domains. While northern blotting revealed only these two mRNAs, both PCR and mRNA-seq detect a single capped and polyadenylated transcript that encodes processed forms of both genes linked by the intergenic region, as well as other transcripts in which exons of the two genes are spliced together. These results might suggest that the two genes are expressed as an operon, during which both genes are co-transcribed and then trans-spliced into two separate messages. This type of transcriptional regulation has been described in tunicates previously; however, the membrane-bound gene does not encode a typical Splice Leader (SL) sequence at the 5' terminus that usually accompanies trans-splicing. Thus, the presence of stable transcripts encoding both genes may suggest a novel mechanism of regulation, or conversely may be rare but stable transcripts in which the two mRNAs are linked due to a small amount of read-through by RNA polymerase. Both genes are highly polymorphic and co-expressed on tissues involved in histocompatibility. In addition, polymorphisms on both genes correlate with outcome, although we have found a case in which it appears that the secreted form may be major allorecognition determinant.

Associations of Leu72Met Polymorphism of Preproghrelin with Ratios of Plasma Lipids Are Diversified by a High-Carbohydrate Diet in Healthy Chinese Adolescents.

PubMed

Su, Mi; Qiu, Li; Wang, Qian; Jiang, Zhen; Liu, Xiao Juan; Lin, Jia; Fang, Ding Zhi

2015-01-01

The association of preproghrelin Leu72Met polymorphism with plasma lipids profile was inconsistently reported and needs more studies to be confirmed. Our study was to investigate the changes of plasma lipids ratios after a high-carbohydrate (high-CHO) diet in healthy Chinese adolescents with different genotypes of this polymorphism. Fifty-three healthy university students were given a washout diet of 54.1% carbohydrate for 7 days, followed by a high-CHO diet of 70.1% carbohydrate for 6 days. The anthropometric and biological parameters were analyzed at baseline and before and after the high-CHO diet. When compared with those before the high-CHO diet, body mass index (BMI) decreased in the male and female Met72 allele carriers. Decreased low-/high-density lipoprotein cholesterol (LDL-C/HDL-C) was observed in all participants except the female subjects with the Leu72Leu genotype. TG/HDL-C and log (TG/HDL-C) were increased only in the female subjects with the Leu72Leu genotype. These results suggest that the Met72 allele of preproghrelin Leu72Met polymorphism may be associated with decreased BMI induced by the high-CHO diet in male and female adolescents, while the Leu72 allele with increased TG/HDL-C and log (TG/HDL-C) in the female adolescents only. Furthermore, the decreasing effect of the high-CHO diet on LDL/HDL-C may be eliminated in the female Leu72Leu homozygotes. © 2015 S. Karger AG, Basel.

Single nucleotide polymorphisms associated with thermoregulation in lactating dairy cows exposed to heat stress.

PubMed

Dikmen, S; Wang, X-z; Ortega, M S; Cole, J B; Null, D J; Hansen, P J

2015-12-01

Dairy cows with increased rectal temperature experience lower milk yield and fertility. Rectal temperature during heat stress is heritable, so genetic selection for body temperature regulation could reduce effects of heat stress on production. One aim of the study was to validate the relationship between genotype and heat tolerance for single nucleotide polymorphisms (SNPs) previously associated with resistance to heat stress. A second aim was to identify new SNPs associated with heat stress resistance. Thermotolerance was assessed in lactating Holsteins during the summer by measuring rectal temperature (a direct measurement of body temperature regulation; n = 435), respiration rate (an indirect measurement of body temperature regulation, n = 450) and sweating rate (the major evaporative cooling mechanism in cattle, n = 455). The association between genotype and thermotolerance was evaluated for 19 SNPs previously associated with rectal temperature from a genomewide analysis study (GWAS), four SNPs previously associated with change in milk yield during heat stress from GWAS, 2 candidate gene SNPs previously associated with rectal temperature and respiration rate during heat stress (ATPA1A and HSP70A) and 66 SNPs in genes previously shown to be associated with reproduction, production or health traits in Holsteins. For SNPs previously associated with heat tolerance, regions of BTA4, BTA6 and BTA24 were associated with rectal temperature; regions of BTA6 and BTA24 were associated with respiration rate; and regions of BTA5, BTA26 and BTA29 were associated with sweating rate. New SNPs were identified for rectal temperature (n = 12), respiration rate (n = 8) and sweating rate (n = 3) from among those previously associated with production, reproduction or health traits. The SNP that explained the most variation were PGR and ASL for rectal temperature, ACAT2 and HSD17B7 for respiration rate, and ARL6IP1 and SERPINE2 for sweating rate. ARL6IP1 was associated with all three thermotolerance traits. In conclusion, specific genetic markers responsible for genetic variation in thermoregulation during heat stress in Holsteins were identified. These markers may prove useful in genetic selection for heat tolerance in Holstein cattle. © 2015 Blackwell Verlag GmbH.

Genetic variation in the cannabinoid receptor gene (CNR1) (G1359A polymorphism) and their influence on anthropometric parameters and metabolic parameters under a high monounsaturated vs. high polyunsaturated fat hypocaloric diets.

PubMed

de Luis, Daniel Antonio; Aller, Rocio; Gonzalez Sagrado, Manuel; Conde, Rosa; Izaola, Olatz; de la Fuente, Beatriz

2013-08-01

An intragenic polymorphism (1359 G/A) of the cannabinoid receptor 1 (CNR1) gene was reported as a common polymorphism in Caucasian populations (rs1049353). Intervention studies with this polymorphism have yield contradictories results. We decide to investigate the role of polymorphism (G1359A) of (CNR1) gene on metabolic parameters and weight loss secondary to a high monounsaturated fat and high polyunsaturated fat hypocaloric diets in obese subjects. A population of 258 obese subjects was analyzed in a randomized trial. A nutritional evaluation was performed at the beginning and at the end of a 3-month period in which subjects received 1 of 2 diets (diet M: high monounsaturated fat diet vs diet P: high polyunsaturated fat diet). One hundred and sixty five patients (63.9%) had the genotype G1359G and 93 (36.1%) patients (A allele carriers) had G1359A (78 patients,30.3%) or A1359A (15 patients,5.8%) genotypes. In subjects with both genotypes, body mass index, weight, fat mass, waist circumference and systolic blood pressures decreased with both diets. With the diet-type M and in both genotype groups, biochemical parameters remained unchanged. After the diet type P and in subjects with both genotypes, glucose, total cholesterol, low-density lipoprotein (LDL) cholesterol, insulin and homeostasis model assessment for insulin resistance (HOMA-IR) levels decreased. In G1359G genotype subjects after both diets, leptin levels decreased. The finding of this study is the association of the A allele with a lack of improvement on leptin levels. Subjects with both genotypes and after a high polyunsaturated fat hypocaloric diet showed a significant improvement of LDL cholesterol, total cholesterol, HOMA-IR and insulin levels. Copyright © 2013 Elsevier Inc. All rights reserved.

Polymorph Impact on the Bioavailability and Stability of Poorly Soluble Drugs.

PubMed

Censi, Roberta; Di Martino, Piera

2015-10-15

Drugs with low water solubility are predisposed to poor and variable oral bioavailability and, therefore, to variability in clinical response, that might be overcome through an appropriate formulation of the drug. Polymorphs (anhydrous and solvate/hydrate forms) may resolve these bioavailability problems, but they can be a challenge to ensure physicochemical stability for the entire shelf life of the drug product. Since clinical failures of polymorph drugs have not been uncommon, and some of them have been entirely unexpected, the Food and Drug Administration (FDA) and the International Conference on Harmonization (ICH) has required preliminary and exhaustive screening studies to identify and characterize all the polymorph crystal forms for each drug. In the past, the polymorphism of many drugs was detected fortuitously or through manual time consuming methods; today, drug crystal engineering, in particular, combinatorial chemistry and high-throughput screening, makes it possible to easily and exhaustively identify stable polymorphic and/or hydrate/dehydrate forms of poorly soluble drugs, in order to overcome bioavailability related problems or clinical failures. This review describes the concepts involved, provides examples of drugs characterized by poor solubility for which polymorphism has proven important, outlines the state-of-the-art technologies and discusses the pertinent regulations.

Epitaxial stabilization and phase instability of VO2 polymorphs

NASA Astrophysics Data System (ADS)

Lee, Shinbuhm; Ivanov, Ilia N.; Keum, Jong K.; Lee, Ho Nyung

2016-01-01

The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide spectrum of functionalities useful for many potential applications in information and energy technologies. However, synthesis of phase pure materials, especially in thin film forms, has been a challenging task due to the fact that the VO2 polymorphs are closely related to each other in a thermodynamic framework. Here, we report epitaxial stabilization of the VO2 polymorphs to synthesize high quality single crystalline thin films and study the phase stability of these metastable materials. We selectively deposit all the phases on various perovskite substrates with different crystallographic orientations. By investigating the phase instability, phonon modes and transport behaviours, not only do we find distinctively contrasting physical properties of the VO2 polymorphs, but that the polymorphs can be on the verge of phase transitions when heated as low as ~400 °C. Our successful epitaxy of both VO2(A) and VO2(B) phases, which are rarely studied due to the lack of phase pure materials, will open the door to the fundamental studies of VO2 polymorphs for potential applications in advanced electronic and energy devices.

Epitaxial stabilization and phase instability of VO2 polymorphs.

PubMed

Lee, Shinbuhm; Ivanov, Ilia N; Keum, Jong K; Lee, Ho Nyung

2016-01-20

The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide spectrum of functionalities useful for many potential applications in information and energy technologies. However, synthesis of phase pure materials, especially in thin film forms, has been a challenging task due to the fact that the VO2 polymorphs are closely related to each other in a thermodynamic framework. Here, we report epitaxial stabilization of the VO2 polymorphs to synthesize high quality single crystalline thin films and study the phase stability of these metastable materials. We selectively deposit all the phases on various perovskite substrates with different crystallographic orientations. By investigating the phase instability, phonon modes and transport behaviours, not only do we find distinctively contrasting physical properties of the VO2 polymorphs, but that the polymorphs can be on the verge of phase transitions when heated as low as ~400 °C. Our successful epitaxy of both VO2(A) and VO2(B) phases, which are rarely studied due to the lack of phase pure materials, will open the door to the fundamental studies of VO2 polymorphs for potential applications in advanced electronic and energy devices.

Epitaxial stabilization and phase instability of VO2 polymorphs

PubMed Central

Lee, Shinbuhm; Ivanov, Ilia N.; Keum, Jong K.; Lee, Ho Nyung

2016-01-01

The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide spectrum of functionalities useful for many potential applications in information and energy technologies. However, synthesis of phase pure materials, especially in thin film forms, has been a challenging task due to the fact that the VO2 polymorphs are closely related to each other in a thermodynamic framework. Here, we report epitaxial stabilization of the VO2 polymorphs to synthesize high quality single crystalline thin films and study the phase stability of these metastable materials. We selectively deposit all the phases on various perovskite substrates with different crystallographic orientations. By investigating the phase instability, phonon modes and transport behaviours, not only do we find distinctively contrasting physical properties of the VO2 polymorphs, but that the polymorphs can be on the verge of phase transitions when heated as low as ~400 °C. Our successful epitaxy of both VO2(A) and VO2(B) phases, which are rarely studied due to the lack of phase pure materials, will open the door to the fundamental studies of VO2 polymorphs for potential applications in advanced electronic and energy devices. PMID:26787259

Polymorphism in 'L' shaped lipids: structure of N-, O-diacylethanolamines with mixed acyl chains.

PubMed

Tarafdar, Pradip K; Swamy, Musti J

2009-11-01

Although solid state polymorphism in lipids has been established by spectroscopic and calorimetric studies long ago, only in a few cases crystal structures of different polymorphs of the same compound have been reported, possibly due to difficulties in obtaining high quality single crystals of individual polymorphs. Recent studies show that N-, O-diacylethanolamines (DAEs) can be derived by the O-acylation of the stress-related lipids, the N-acylethanolamines under physiological conditions. In this study, two DAEs with mixed acyl chains, namely N-palmitoyl, O-octanoylethanolamine and N-palmitoyl, O-decanoylethanolamine have been synthesized and their three-dimensional structures were determined. Both the compounds were found to adopt 'L' shaped structures and exist in two polymorphic forms, alpha and beta. In the alpha form a mixed-type chain packing has been observed whereas in the beta form the chain packing is symmetric. Similar polymorphic forms are likely to exist in other 'L' shaped lipids such as 1,3-diacylglycerols and ceramides, where polymorphism has been detected earlier, but three-dimensional structures - which can give precise information about the packing at atomic resolution - have not been reported.

Nanomechanical properties of distinct fibrillar polymorphs of the protein α-synuclein.

PubMed

Makky, Ali; Bousset, Luc; Polesel-Maris, Jérôme; Melki, Ronald

2016-11-30

Alpha-synuclein (α-Syn) is a small presynaptic protein of 140 amino acids. Its pathologic intracellular aggregation within the central nervous system yields protein fibrillar inclusions named Lewy bodies that are the hallmarks of Parkinson's disease (PD). In solution, pure α-Syn adopts an intrinsically disordered structure and assembles into fibrils that exhibit considerable morphological heterogeneity depending on their assembly conditions. We recently established tightly controlled experimental conditions allowing the assembly of α-Syn into highly homogeneous and pure polymorphs. The latter exhibited differences in their shape, their structure but also in their functional properties. We have conducted an AFM study at high resolution and performed a statistical analysis of fibrillar α-Syn shape and thermal fluctuations to calculate the persistence length to further assess the nanomechanical properties of α-Syn polymorphs. Herein, we demonstrated quantitatively that distinct polymorphs made of the same protein (wild-type α-Syn) show significant differences in their morphology (height, width and periodicity) and physical properties (persistence length, bending rigidity and axial Young's modulus).

Nanomechanical properties of distinct fibrillar polymorphs of the protein α-synuclein

NASA Astrophysics Data System (ADS)

Makky, Ali; Bousset, Luc; Polesel-Maris, Jérôme; Melki, Ronald

2016-11-01

Alpha-synuclein (α-Syn) is a small presynaptic protein of 140 amino acids. Its pathologic intracellular aggregation within the central nervous system yields protein fibrillar inclusions named Lewy bodies that are the hallmarks of Parkinson’s disease (PD). In solution, pure α-Syn adopts an intrinsically disordered structure and assembles into fibrils that exhibit considerable morphological heterogeneity depending on their assembly conditions. We recently established tightly controlled experimental conditions allowing the assembly of α-Syn into highly homogeneous and pure polymorphs. The latter exhibited differences in their shape, their structure but also in their functional properties. We have conducted an AFM study at high resolution and performed a statistical analysis of fibrillar α-Syn shape and thermal fluctuations to calculate the persistence length to further assess the nanomechanical properties of α-Syn polymorphs. Herein, we demonstrated quantitatively that distinct polymorphs made of the same protein (wild-type α-Syn) show significant differences in their morphology (height, width and periodicity) and physical properties (persistence length, bending rigidity and axial Young’s modulus).

Polymorphism at the merozoite surface protein-3alpha locus of Plasmodium vivax: global and local diversity.

PubMed

Bruce, M C; Galinski, M R; Barnwell, J W; Snounou, G; Day, K P

1999-10-01

Allelic diversity at the Plasmodium vivax merozoite surface protein-3alpha (PvMsp-3alpha) locus was investigated using a combined polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) protocol. Symptomatic patient isolates from global geographic origins showed a high level of polymorphism at the nucleotide level. These samples were used to validate the sensitivity, specificity, and reproducibility of the PCR/RFLP method. It was then used to investigate PvMsp3alpha diversity in field samples from children living in a single village in a malaria-endemic region of Papua New Guinea, with the aim of assessing the usefulness of this locus as an epidemiologic marker of P. vivax infections. Eleven PvMsp-3alpha alleles were distinguishable in 16 samples with single infections, revealing extensive parasite polymorphism within this restricted area. Multiple infections were easily detected and accounted for 5 (23%) of 22 positive samples. Pairs of samples from individual children provided preliminary evidence for high turnover of P. vivax populations.

Reducing the Schottky barrier between few-layer MoTe2 and gold

NASA Astrophysics Data System (ADS)

Qi, Dianyu; Wang, Qixing; Han, Cheng; Jiang, Jizhou; Zheng, Yujie; Chen, Wei; Zhang, Wenjing; Thye Shen Wee, Andrew

2017-12-01

Schottky barriers greatly influence the performance of optoelectronic devices. Schottky barriers can be reduced by harnessing the polymorphism of 2D metal transition dichalcogenides, since both semiconducting and metallic phases exist. However, high energy, high temperature or chemicals are normally required for phase transformation, or the processes are complex. In this work, stable low-resistance contacts between few layer MoTe2 flakes and gold electrodes are achieved by a simple thermal annealing treatment at low temperature (200-400 °C). The resulting Schottky barrier height of the annealed MoTe2/Au interface is low (~23 meV). A new Raman A g mode of the 1T‧ metallic phase of MoTe2 on gold electrode is observed, indicating that the low-resistance contact is due to the phase transition of 2H-MoTe2. The gold substrate plays an important role in the transformation, and a higher gold surface roughness increases the transformation rate. With this method, the mobility and ON-state current of the MoTe2 transistor increase by ~3-4 orders of magnitude, the photocurrent of vertically stacked graphene/MoTe2/Au device increases ~300%, and the response time decreases by ~20%.

Diversity of Methane-Oxidizing Bacteria in Soils from “Hot Lands of Medolla” (Italy) Featured by Anomalous High-Temperatures and Biogenic CO2 Emission

PubMed Central

Cappelletti, Martina; Ghezzi, Daniele; Zannoni, Davide; Capaccioni, Bruno; Fedi, Stefano

2016-01-01

“Terre Calde di Medolla” (TCM) (literally, “Hot Lands of Medolla”) refers to a farming area in Italy with anomalously high temperatures and diffuse emissions of biogenic CO2, which has been linked to CH4 oxidation processes from a depth of 0.7 m to the surface. We herein assessed the composition of the total bacterial community and diversity of methane-oxidizing bacteria (MOB) in soil samples collected at a depth at which the peak temperature was detected (0.6 m). Cultivation-independent methods were used, such as: i) a clone library analysis of the 16S rRNA gene and pmoA (coding for the α-subunit of the particulate methane monooxygenase) gene, and ii) Terminal Restriction Fragment Length Polymorphism (T-RFLP) fingerprinting. The 16S rRNA gene analysis assessed the predominance of Actinobacteria, Acidobacteria, Proteobacteria, and Bacillus in TCM samples collected at a depth of 0.6 m along with the presence of methanotrophs (Methylocaldum and Methylobacter) and methylotrophs (Methylobacillus). The phylogenetic analysis of pmoA sequences showed the presence of MOB affiliated with Methylomonas, Methylocystis, Methylococcus, and Methylocaldum in addition to as yet uncultivated and uncharacterized methanotrophs. Jaccard’s analysis of T-RFLP profiles at different ground depths revealed a similar MOB composition in soil samples at depths of 0.6 m and 0.7 m, while this similarity was weaker between these samples and those taken at a depth of 2.5 m, in which the genus Methylocaldum was absent. These results correlate the anomalously high temperatures of the farming area of “Terre Calde di Medolla” with the presence of microbial methane-oxidizing bacteria. PMID:27645100

Diversity of Methane-Oxidizing Bacteria in Soils from "Hot Lands of Medolla" (Italy) Featured by Anomalous High-Temperatures and Biogenic CO2 Emission.

PubMed

Cappelletti, Martina; Ghezzi, Daniele; Zannoni, Davide; Capaccioni, Bruno; Fedi, Stefano

2016-12-23

"Terre Calde di Medolla" (TCM) (literally, "Hot Lands of Medolla") refers to a farming area in Italy with anomalously high temperatures and diffuse emissions of biogenic CO 2 , which has been linked to CH 4 oxidation processes from a depth of 0.7 m to the surface. We herein assessed the composition of the total bacterial community and diversity of methane-oxidizing bacteria (MOB) in soil samples collected at a depth at which the peak temperature was detected (0.6 m). Cultivation-independent methods were used, such as: i) a clone library analysis of the 16S rRNA gene and pmoA (coding for the α-subunit of the particulate methane monooxygenase) gene, and ii) Terminal Restriction Fragment Length Polymorphism (T-RFLP) fingerprinting. The 16S rRNA gene analysis assessed the predominance of Actinobacteria, Acidobacteria, Proteobacteria, and Bacillus in TCM samples collected at a depth of 0.6 m along with the presence of methanotrophs (Methylocaldum and Methylobacter) and methylotrophs (Methylobacillus). The phylogenetic analysis of pmoA sequences showed the presence of MOB affiliated with Methylomonas, Methylocystis, Methylococcus, and Methylocaldum in addition to as yet uncultivated and uncharacterized methanotrophs. Jaccard's analysis of T-RFLP profiles at different ground depths revealed a similar MOB composition in soil samples at depths of 0.6 m and 0.7 m, while this similarity was weaker between these samples and those taken at a depth of 2.5 m, in which the genus Methylocaldum was absent. These results correlate the anomalously high temperatures of the farming area of "Terre Calde di Medolla" with the presence of microbial methane-oxidizing bacteria.

Thermodynamic investigation of the phase equilibrium boundary between TiO2 rutile and its α-PbO2-type high-pressure polymorph

NASA Astrophysics Data System (ADS)

Kojitani, Hiroshi; Yamazaki, Monami; Kojima, Meiko; Inaguma, Yoshiyuki; Mori, Daisuke; Akaogi, Masaki

2018-06-01

Heat capacity (C P) of rutile and α-PbO2 type TiO2 (TiO2-II) were measured by the differential scanning calorimetry and thermal relaxation method. Using the results, standard entropies at 1 atm and 298.15 K of rutile and TiO2-II were determined to be 50.04(4) and 46.54(2) J/mol K, respectively. Furthermore, thermal expansivity (α) determined by high-temperature X-ray diffraction measurement and mode Grüneisen parameters obtained by high-pressure Raman spectroscopy suggested the thermal Grüneisen parameter (γ th) for TiO2-II of 1.7(1). By applying the obtained low-temperature C P and γ th, the measured C P and α data of TiO2-II were extrapolated to higher temperature region using a lattice vibrational model calculation, as well as rutile. Internally consistent thermodynamic data sets of both rutile and TiO2-II assessed in this study were used to thermodynamically calculate the rutile‒TiO2-II phase equilibrium boundary. The most plausible boundary was obtained to be P (GPa) = 0.0074T (K) - 1.7. Our boundary suggests that the crystal growth of TiO2-II observed below 5.5 GPa and 900 K in previous studies advanced in its stability field. The phase boundary calculation also suggested small, exothermic phase transition enthalpy from rutile to TiO2-II at 1 atm and 298.15 K of - 0.5 to - 1.1 kJ/mol. This implies that the thermodynamic stability of rutile at 1 atm above room temperature is due to larger contribution of entropy term.

Effects of Temperature on the Meiotic Recombination Landscape of the Yeast Saccharomyces cerevisiae

PubMed Central

Zhang, Ke; Wu, Xue-Chang

2017-01-01

ABSTRACT Although meiosis in warm-blooded organisms takes place in a narrow temperature range, meiosis in many organisms occurs over a wide variety of temperatures. We analyzed the properties of meiosis in the yeast Saccharomyces cerevisiae in cells sporulated at 14°C, 30°C, or 37°C. Using comparative-genomic-hybridization microarrays, we examined the distribution of Spo11-generated meiosis-specific double-stranded DNA breaks throughout the genome. Although there were between 300 and 400 regions of the genome with high levels of recombination (hot spots) observed at each temperature, only about 20% of these hot spots were found to have occurred independently of the temperature. In S. cerevisiae, regions near the telomeres and centromeres tend to have low levels of meiotic recombination. This tendency was observed in cells sporulated at 14°C and 30°C, but not at 37°C. Thus, the temperature of sporulation in yeast affects some global property of chromosome structure relevant to meiotic recombination. Using single-nucleotide polymorphism (SNP)-specific whole-genome microarrays, we also examined crossovers and their associated gene conversion events as well as gene conversion events that were unassociated with crossovers in all four spores of tetrads obtained by sporulation of diploids at 14°C, 30°C, or 37°C. Although tetrads from cells sporulated at 30°C had slightly (20%) more crossovers than those derived from cells sporulated at the other two temperatures, spore viability was good at all three temperatures. Thus, despite temperature-induced variation in the genetic maps, yeast cells produce viable haploid products at a wide variety of sporulation temperatures. PMID:29259092

Poly (vinylsulfonic acid) assisted synthesis of aqueous solution stable vaterite calcium carbonate nanoparticles.

PubMed

Nagaraja, Ashvin T; Pradhan, Sulolit; McShane, Michael J

2014-03-15

Calcium carbonate nanoparticles of the vaterite polymorph were synthesized by combining CaCl2 and Na2CO3 in the presence of poly (vinylsulfonic acid) (PVSA). By studying the important experimental parameters we found that controlling PVSA concentration, reaction temperature, and order of reagent addition the particle size, monodispersity, and surface charge can be controlled. By increasing PVSA concentration or by decreasing temperature CCNPs with an average size from ≈150 to 500 nm could be produced. We believe the incorporation of PVSA into the reaction plays a dual role to (1) slow down the nucleation rate by sequestering calcium and to (2) stabilize the resulting CCNPs as the vaterite polymorph, preventing surface calcification or aggregation into microparticles. The obtained vaterite nanoparticles were found to maintain their crystal structure and surface charge after storage in aqueous buffer for at least 5 months. The aqueous stable vaterite nanoparticles could be a useful platform for the encapsulation of a large variety of biomolecules for drug delivery or as a sacrificial template toward capsule formation for biosensor applications. Copyright © 2013 Elsevier Inc. All rights reserved.

A study of ethanol reactions on O2-treated Au/TiO2. Effect of support and metal loading on reaction selectivity

NASA Astrophysics Data System (ADS)

Nadeem, M. A.; Waterhouse, G. I. N.; Idriss, H.

2016-08-01

The reactions of ethanol have been studied on bare and Au supported TiO2 polymorphs (anatase and rutile) in order to understand the effect of Au loading and prior O2 treatment on the reaction selectivity and conversion using temperature programmed desorption (TPD). Although O2 treatment has negligible effect on the reaction selectivity of ethanol on TiO2 alone it considerably affects the reaction on Au/TiO2. Au/TiO2 had three main effects on the reaction when compared to TiO2 alone. First, it switches the reaction selectivity of the dehydration (to ethylene) in favor of dehydrogenation (to acetaldehyde) on both polymorphs. Second, it decreases the desorption temperature of the main reaction products. Third, it increases secondary reaction products (mainly C4 (crotonaldehyde, butene, furan) reaching ca. 78% of the overall carbon selectivity for the 8 wt.% Au/TiO2 anatase. These effects are more pronounced on the anatase phase when compared to that on the rutile phase. Reasons for these are discussed.

Synthesis of kalsilite from microcline powder by an alkali-hydrothermal process

NASA Astrophysics Data System (ADS)

Su, Shuang-qing; Ma, Hong-wen; Yang, Jing; Zhang, Pan; Luo, Zheng

2014-08-01

The properties of aluminosilicate kalsilite have attracted the interest of researchers in chemical synthesis, ceramic industry, biofuels, etc. In this study, kalsilite was hydrothermally synthesized from microcline powder in a KOH solution. The microcline powder, rich in potassium, aluminum, and silicon, was collected from Mountain Changling in Northwestern China. The effects of temperature, time, and KOH concentration on the decomposition of microcline were investigated. The kalsilite and intermediate products were characterized by means of wet chemistry analysis, X-ray Diffraction (XRD), infrared spectrometry (IR), 29Si magic angle spinning nuclear magnetic resonance (29Si MAS NMR), 27Al MAS NMR, and scanning electron microscope (SEM). With increasing temperature, the microcline powder transforms into a metastable KAlSiO4 polymorph before transforming further into pure kalsilite. A mixture of both kalsilite and metastable KAlSiO4 polymorph is obtained when the hydrothermal reaction is carried out within 2 h; but after 2 h, kalsilite is the predominant product. The concentration of KOH, which needs to be larger than 4.3 M, is an important parameter influencing the synthesis of kalsilite.

Further exploration of the conformational space of α-synuclein fibrils: solid-state NMR assignment of a high-pH polymorph.

PubMed

Verasdonck, Joeri; Bousset, Luc; Gath, Julia; Melki, Ronald; Böckmann, Anja; Meier, Beat H

2016-04-01

Polymorphism is a common and important phenomenon for protein fibrils which has been linked to the appearance of strains in prion and other neurodegenerative diseases. Parkinson disease is a frequently occurring neurodegenerative pathology, tightly associated with the formation of Lewy bodies. These deposits mainly consist of α-synuclein in fibrillar, β-sheet-rich form. α-synuclein is known to form numerous different polymorphs, which show distinct structural features. Here, we describe the chemical shift assignments, and derive the secondary structure, of a polymorph that was fibrillized at higher-than-physiological pH conditions. The fibrillar core contains residues 40-95, with both the C- and N-terminus not showing any ordered, rigid parts. The chemical shifts are similar to those recorded previously for an assigned polymorph that was fibrillized at neutral pH.

DNA methylation polymorphism in flue-cured tobacco and candidate markers for tobacco mosaic virus resistance*

PubMed Central

Zhao, Jie-hong; Zhang, Ji-shun; Wang, Yi; Wang, Ren-gang; Wu, Chun; Fan, Long-jiang; Ren, Xue-liang

2011-01-01

DNA methylation plays an important role in the epigenetic regulation of gene expression during plant growth, development, and polyploidization. However, there is still no distinct evidence in tobacco regarding the distribution of the methylation pattern and whether it contributes to qualitative characteristics. We studied the levels and patterns of methylation polymorphism at CCGG sites in 48 accessions of allotetraploid flue-cured tobacco, Nicotiana tabacum, using a methylation-sensitive amplified polymorphism (MSAP) technique. The results showed that methylation existed at a high level among tobacco accessions, among which 49.3% sites were methylated and 69.9% allelic sites were polymorphic. A cluster analysis revealed distinct patterns of geography-specific groups. In addition, three polymorphic sites significantly related to tobacco mosaic virus (TMV) resistance were explored. This suggests that tobacco breeders should pay more attention to epigenetic traits. PMID:22042659

Association of Gene Polymorphisms in Interleukin 6 in Infantile Bronchial Asthma.

PubMed

Babusikova, Eva; Jurecekova, Jana; Jesenak, Milos; Evinova, Andrea

2017-07-01

The genetic background of bronchial asthma is complex, and it is likely that multiple genes contribute to its development both directly and through gene-gene interactions. Cytokines contribute to different aspects of asthma, as they determine the type, severity and outcomes of asthma pathogenesis. Allergic asthmatics undergoing an asthmatic attack exhibit significantly higher levels of pro-inflammatory cytokines, such as interleukins and chemokines. In recent years, cytokines and their receptors have been shown to be highly polymorphic, and this prompted us to investigate interleukin 6 promoter polymorphisms at position -174G/C (rs1800795) and at -572G/C (rs1800796) in relation to asthma in children. Interleukin 6 promoter polymorphisms were analyzed in bronchial asthma patients and healthy children using polymerase chain reaction-restriction fragment length polymorphism analysis. We observed a significant association between polymorphism at -174G/C and bronchial asthma (OR=3.4, 95% CI: 2.045-5.638, P<.001). Higher associations between polymorphism at IL-6 -174G/C and bronchial asthma were observed in atopic patients (OR=4.1, 95% CI: 2.308-7.280, P<8.10 -7 ). Interleukin 6 polymorphism is associated with bronchial asthma, particularly its atopic phenotype. Expression and secretion of interleukins in asthmatic patients may be affected by genetic polymorphisms, and could have a disease-modifying effect in the asthmatic airway and modify the therapeutic response. Copyright © 2016 SEPAR. Publicado por Elsevier España, S.L.U. All rights reserved.

Role of annealing temperatures on structure polymorphism, linear and nonlinear optical properties of nanostructure lead dioxide thin films

NASA Astrophysics Data System (ADS)

Zeyada, H. M.; Makhlouf, M. M.

2016-04-01

The powder of as synthesized lead dioxide (PbO2) has polycrystalline structure β-PbO2 phase of tetragonal crystal system. It becomes nanocrystallites α-PbO2 phase with orthorhombic crystal system upon thermal deposition to form thin films. Annealing temperatures increase nanocrystallites size from 28 to 46 nm. The optical properties of α-PbO2 phase were calculated from absolute values of transmittance and reflectance at nearly normal incidence of light by spectrophotometer measurements. The refractive and extinction indices were determined and showed a response to annealing temperatures. The absorption coefficient of α-PbO2 films is >106 cm-1 in UV region of spectra. Analysis of the absorption coefficient spectra near optical edge showed indirect allowed transition. Annealing temperature decreases the value of indirect energy gap for α-PbO2 films. The dispersion parameters such as single oscillator energy, dispersion energy, dielectric constant at high frequency and lattice dielectric constant were calculated and its variations with annealing temperatures are reported. The nonlinear refractive index (n2), third-order nonlinear susceptibility (χ(3)) and nonlinear absorption coefficient (βc) were determined. It was found that χ(3), n2 and β increase with increasing photon energy and decrease with increasing annealing temperature. The pristine film of α-PbO2 has higher values of nonlinear optical constants than for annealed films; therefore it is suitable for applications in manufacturing nonlinear optical devices.

Haptoglobin, alpha-thalassaemia and glucose-6-phosphate dehydrogenase polymorphisms and risk of abnormal transcranial Doppler among patients with sickle cell anaemia in Tanzania.

PubMed

Cox, Sharon E; Makani, Julie; Soka, Deogratias; L'Esperence, Veline S; Kija, Edward; Dominguez-Salas, Paula; Newton, Charles R J; Birch, Anthony A; Prentice, Andrew M; Kirkham, Fenella J

2014-06-01

Transcranial Doppler ultrasonography measures cerebral blood flow velocity (CBFv) of basal intracranial vessels and is used clinically to detect stroke risk in children with sickle cell anaemia (SCA). Co-inheritance in SCA of alpha-thalassaemia and glucose-6-phosphate dehydrogenase (G6PD) polymorphisms is reported to associate with high CBFv and/or risk of stroke. The effect of a common functional polymorphism of haptoglobin (HP) is unknown. We investigated the effect of co-inheritance of these polymorphisms on CBFv in 601 stroke-free Tanzanian SCA patients aged <24 years. Homozygosity for alpha-thalassaemia 3·7 deletion was significantly associated with reduced mean CBFv compared to wild-type (β-coefficient -16·1 cm/s, P = 0·002) adjusted for age and survey year. Inheritance of 1 or 2 alpha-thalassaemia deletions was associated with decreased risk of abnormally high CBFv, compared to published data from Kenyan healthy control children (Relative risk ratio [RRR] = 0·53 [95% confidence interval (CI):0·35-0·8] & RRR = 0·43 [95% CI:0·23-0·78]), and reduced risk of abnormally low CBFv for 1 deletion only (RRR = 0·38 [95% CI:0·17-0·83]). No effects were observed for G6PD or HP polymorphisms. This is the first report of the effects of co-inheritance of common polymorphisms, including the HP polymorphism, on CBFv in SCA patients resident in Africa and confirms the importance of alpha-thalassaemia in reducing risk of abnormal CBFv. © 2014 The Authors. British Journal of Haematology Published by John Wiley & Sons Ltd.

Presence of Peierls pairing and absence of insulator-to-metal transition in VO2 (A): a structure-property relationship study.

PubMed

Popuri, S R; Artemenko, A; Decourt, R; Villesuzanne, A; Pollet, M

2017-03-01

Layered vanadium oxides have been extensively explored due to their interesting metal-insulator transitions and energy conversion/storage applications. In the present study, we have successfully synthesized VO 2 (A) polymorph powder samples by a single-step hydrothermal synthesis process and consolidated them using spark plasma sintering. The structural and electronic properties of VO 2 (A) are measured over a large temperature range from liquid helium, across the structural transition (400-440 K) and up to 500 K. The structural analysis around this transition reveals an antiferrodistorsive to partially ferrodistorsive ordering upon cooling. It is followed by a progressive antiferromagnetic spin pairing which fully settles at about 150 K. The transport measurements show that, in contrast to the rutile archetype VO 2 (R/M1), the structural transition comes with a transition from semiconductor to band-type insulator. Under these circumstances, we propose a scenario with a high temperature antiferrodistorsive paramagnetic semiconducting phase, followed by an intermediate regime with a partially ferrodistorsive paramagnetic semiconducting phase, and finally a low temperature partially ferrodistorsive antiferromagnetic band insulator phase with a possible V-V Peierls-type pairing.

Influence of Folate-Related Gene Polymorphisms on High-Dose Methotrexate-Related Toxicity and Prognosis in Turkish Children with Acute Lymphoblastic Leukemia.

PubMed

Yazıcıoğlu, Burcu; Kaya, Zühre; Güntekin Ergun, Sezen; Perçin, Ferda; Koçak, Ülker; Yenicesu, İdil; Gürsel, Türkiz

2017-06-05

High-dose methotrexate (HD-MTX) is widely used in the consolidation phase of childhood acute lymphoblastic leukemia (ALL), but the roles that polymorphisms in folate-related genes (FRGs) play in HD-MTX toxicity and prognosis in children with ALL are not understood. The aims of this study were to investigate the frequencies of polymorphisms in the genes for thymidylate synthase (TS), methionine synthase reductase (MTRR), and methylene tetrahydrofolate reductase (MTHFR) in Turkish children with ALL and to assess associations between these polymorphisms and HD-MTX-related toxicity and leukemia prognosis in this patient group. FRG polymorphisms were assessed by real-time polymerase chain reaction. Survival status, MTX levels, and toxicity data were retrieved from 106 patients' charts. The allele frequencies for the FRG polymorphisms were as follows: TS 2R 41.0%, 3R 57.0%, and 4R 2.0%; MTRR 66A 42.4% and 66G 57.6%; MTHFR 677C 59.3% and 677T 40.7%; and MTHFR 1298A 58.1% and 1298C 41.9%. At the 48th hour of HD-MTX infusion, serum MTX was significantly higher in patients who had TS 2R/3R/4R variants as compared to those with wild-type TS (p<0.05). No significant differences were detected with respect to event-free survival or toxicity between wild-type and other FRG variants. The frequencies of FRG polymorphisms in Turkish children with ALL are similar to those reported in other Caucasian populations. This is the first published finding of the TS 3R/4R variant in the Turkish population. The results indicate that HD-MTX can be tolerated by leukemic children with some polymorphic variants of FRG; thus, it may prevent future risk of leukemic relapse.