Synthesis, spectra and X-ray crystallography of dipyridin-2-ylmethanone oxime and its CuX2(oxime)2 complexes: Thermal, Hirshfeld surface and DFT analysis

NASA Astrophysics Data System (ADS)

Warad, Ismail; Abdoh, Muneer; Al Ali, Anas; Shivalingegowda, Naveen; Kumara, Karthik; Zarrouk, Abdelkader; Lokanath, Neartur Krishnappagowda

2018-02-01

Dipyridin-2-ylmethanone oxime (C11H9N3O), was prepared using di-2-pyridyl ketone. The oxime ligand and its neutral CuX2 (oxime)2 (X = Cl or Br) complexes have been identified with the aid of several spectroscopic techniques such as: IR, EI-MS, EA, UV-visible, TG, 1H-NMR and finally the structure of the free oxime ligand was confirmed by X-ray diffraction studies. The oxime crystallizes in the monoclinic space group P21/c, with cell parameters a = 8.8811 (8) Å, b = 10.6362 (8) Å, c = 11.2050 (8) Å, β = 109.085 (4) º, V = 1000.26 (14) Å3 and Z = 4. The molecular conformation is stabilized by a strong intramolecular Osbnd H⋯N hydrogen bonding between the hydroxyl group of the oxime moiety and the nitrogen of the pyridine ring. Since the oxime structure was solved by XRD, the ligand structure parameters like bond length and angles were compared to the DFT computed one, the UV-visible to TD-SCF and Hirshfeld surface to MEP analysis.

Crystal structure and electronic properties of a thiolate-protected Au24 nanocluster

NASA Astrophysics Data System (ADS)

Das, Anindita; Li, Tao; Li, Gao; Nobusada, Katsuyuki; Zeng, Chenjie; Rosi, Nathaniel L.; Jin, Rongchao

2014-05-01

Solving the total structures of gold nanoclusters is of critical importance for understanding their electronic, optical and catalytic properties. Herein, we report the X-ray structure of a charge-neutral Au24(SCH2Ph-tBu)20 nanocluster. This structure features a bi-tetrahedral Au8 kernel protected by four tetrameric staple-like motifs. Electronic structure analysis is further carried out and the optical absorption spectrum is interpreted. The Au24(SCH2Ph-tBu)20, Au23(S-c-C6H11)16 and Au25(SCH2CH2Ph)18 nanoclusters constitute the first crystallographically characterized ``trio''.Solving the total structures of gold nanoclusters is of critical importance for understanding their electronic, optical and catalytic properties. Herein, we report the X-ray structure of a charge-neutral Au24(SCH2Ph-tBu)20 nanocluster. This structure features a bi-tetrahedral Au8 kernel protected by four tetrameric staple-like motifs. Electronic structure analysis is further carried out and the optical absorption spectrum is interpreted. The Au24(SCH2Ph-tBu)20, Au23(S-c-C6H11)16 and Au25(SCH2CH2Ph)18 nanoclusters constitute the first crystallographically characterized ``trio''. Electronic supplementary information (ESI) available: Experimental and supporting Fig. S1-S3. CCDC NUMBER(1000102). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4nr01350f

Computational design of thermostabilizing point mutations for G protein-coupled receptors

PubMed Central

Popov, Petr; Peng, Yao; Shen, Ling; Stevens, Raymond C; Cherezov, Vadim; Liu, Zhi-Jie

2018-01-01

Engineering of GPCR constructs with improved thermostability is a key for successful structural and biochemical studies of this transmembrane protein family, targeted by 40% of all therapeutic drugs. Here we introduce a comprehensive computational approach to effective prediction of stabilizing mutations in GPCRs, named CompoMug, which employs sequence-based analysis, structural information, and a derived machine learning predictor. Tested experimentally on the serotonin 5-HT2C receptor target, CompoMug predictions resulted in 10 new stabilizing mutations, with an apparent thermostability gain ~8.8°C for the best single mutation and ~13°C for a triple mutant. Binding of antagonists confers further stabilization for the triple mutant receptor, with total gains of ~21°C as compared to wild type apo 5-HT2C. The predicted mutations enabled crystallization and structure determination for the 5-HT2C receptor complexes in inactive and active-like states. While CompoMug already shows high 25% hit rate and utility in GPCR structural studies, further improvements are expected with accumulation of structural and mutation data. PMID:29927385

Interactive Nonlinear Structural Analysis: A Review of the Gifts-Stags Union.

DTIC Science & Technology

1980-03-31

is unfiri* L’NTERACTIVE *iNLINEAR STRUCTURAL ’ ANALYSIS: REVIEW OF THE GIFTS -STG 9 NI0N! 3r’ac N Wl4-79-C~7 *jbLMSC/D686137 2731 Marobu&8O) Prpr- y G...14 4 Organization of the GIFTS Global Data-Base . . . 15 5 The STAGS Movers ..... ................ . 16 6 Transformers (Long-Distance Movers...17 7 The GIFTS *-’ STAGS Transformation . ....... . 18 8 Role of Control ................ 15 9 The GIFTS -STAGS Control Module: GIST ..... . 20 10 A

Structural Basis by Which Alternative Splicing Modulates the Organizer Activity of FGF8 in the Brain

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

Olsen,S.; Li, J.; Eliseenkova, A.

2006-01-01

Two of the four human FGF8 splice isoforms, FGF8a and FGF8b, are expressed in the mid-hindbrain region during development. Although the only difference between these isoforms is the presence of an additional 11 amino acids at the N terminus of FGF8b, these isoforms possess remarkably different abilities to pattern the midbrain and anterior hindbrain. To reveal the structural basis by which alternative splicing modulates the organizing activity of FGF8, we solved the crystal structure of FGF8b in complex with the 'c' splice isoform of FGF receptor 2 (FGFR2c). Using surface plasmon resonance (SPR), we also characterized the receptor-binding specificity ofmore » FGF8a and FGF8b, the 'b' isoform of FGF17 (FGF17b), and FGF18. The FGF8b-FGFR2c structure shows that alternative splicing permits a single additional contact between phenylalanine 32 (F32) of FGF8b and a hydrophobic groove within Ig domain 3 of the receptor that is also present in FGFR1c, FGFR3c, and FGFR4. Consistent with the structure, mutation of F32 to alanine reduces the affinity of FGF8b toward all these receptors to levels characteristic of FGF8a. More importantly, analysis of the mid-hindbrain patterning ability of the FGF8b{sup F32A} mutant in chick embryos and murine midbrain explants shows that this mutation functionally converts FGF8b to FGF8a. Moreover, our data suggest that the intermediate receptor-binding affinities of FGF17b and FGF18, relative to FGF8a and FGF8b, also account for the distinct patterning abilities of these two ligands. We also show that the mode of FGF8 receptor-binding specificity is distinct from that of other FGFs and provide the first biochemical evidence for a physiological FGF8b-FGFR1c interaction during mid-hindbrain development. Consistent with the indispensable role of FGF8 in embryonic development, we show that the FGF8 mode of receptor binding appeared as early as in nematodes and has been preserved throughout evolution.« less

15N nuclear magnetic resonance studies on the tautomerism of 8-hydroxy-2'-deoxyguanosine, 8-hydroxyguanosine, and other C8-substituted guanine nucleosides.

PubMed

Cho, B P; Kadlubar, F F; Culp, S J; Evans, F E

1990-01-01

The favored tautomeric and ionic structures were examined for the oxidative DNA damage adduct 8-hydroxy-2'-deoxyguanosine and its RNA analogue 8-hydroxyguanosine by 15N NMR spectroscopy. In addition, 15N chemical shifts and coupling constants from 13 different guanine nucleosides, including a wide variety of C8 substitutions (OH, SH, Br, OCH2C6H5, OCH3, SCH3, and SO2CH3), have been analyzed with respect to their tautomeric structures. A -98.5-Hz proton-nitrogen coupling constant observed for the N7 resonance of 8-hydroxyguanosine in dimethyl sulfoxide was evidence for 8-keto substitution, which is contrary to the structure implied by the generally used nomenclature. The pH dependence of 15N NMR spectra of 8-hydroxyguanosine in aqueous solution showed downfield shifts of the N1 and N7 resonances that were greater than 50 ppm, which indicated the conversion from a neutral 6,8-diketo to a 6-enolate-8-keto (pKa1 = 8.6) and finally to a 6,8-dienolate structure (pKa2 = 11.7). There was no evidence of an 8-enol substituent in the absence of ionization. It is proposed that the syn conformation of these oxidized bases in duplex DNA and RNA can be further stabilized by abnormal hydrogen bonding or mispairing that involves N7-H. The combined data show that 15N NMR is a sensitive probe to examine tautomerism of the guanine ring system. The analysis indicates that the change from a single to a double bond for the C8 substituent, and the accompanying removal of the normal double bond between N7 and C8 on the imidazole ring system, has no detectable effect on the tautomerism at the N1-O6 site of the pyrimidine ring system for both the 8-keto and 8-thio substitutions. In addition, large differences in electronegativity of the C8 substituents do not alter the N1-O6 tautomerism.

Ginkgotides: Proline-Rich Hevein-Like Peptides from Gymnosperm Ginkgo biloba

PubMed Central

Wong, Ka H.; Tan, Wei Liang; Serra, Aida; Xiao, Tianshu; Sze, Siu Kwan; Yang, Daiwen; Tam, James P.

2016-01-01

Hevein and hevein-like peptides belong to the family of chitin-binding cysteine-rich peptides. They are classified into three subfamilies, the prototypic 8C- and the 6C- and 10C-hevein-like peptides. Thus far, only five 8C-hevein-like peptides have been characterized from three angiosperms and none from gymnosperm. To determine their occurrence and distribution in the gymnosperm, Ginkgo biloba leaves were examined. Here, we report the discovery and characterization of 11 novel 8C-hevein-like peptides, namely ginkgotides gB1–gB11. Proteomic analysis showed that the ginkgotides contain 41–44 amino acids (aa), a chitin-binding domain and are Pro-rich, a distinguishing feature that differs from other hevein-like peptides. Solution NMR structure determination revealed that gB5 contains a three β-stranded structure shaped by a cystine knot with an additional disulfide bond at the C-terminus. Transcriptomic analysis showed that the ginkgotide precursors contain a three-domain architecture, comprised of a C-terminal tail (20 aa) that is significantly shorter than those of other 8C- and 10C-hevein-like peptides, which generally contain a protein cargo such as a Barwin-like protein (126 aa) or class I chitinase (254 aa). Transcriptomic data mining found an additional 48 ginkgotide homologs in 39 different gymnosperms. Phylogenetic analysis revealed that ginkgotides and their homologs belong to a new class of 8C-hevein-like peptides. Stability studies showed that ginkgotides are highly resistant to thermal, acidic and endopeptidase degradation. Ginkgotides flanked at both the N- and C-terminal ends by Pro were resistant to exopeptidase degradation by carboxypeptidase A and aminopeptidase. Antifungal assays showed that ginkgotides inhibit the hyphal growth of phyto-pathogenic fungi. Taken together, ginkgotides represent the first suite of hevein-like peptides isolated and characterized from gymnosperms. As a group, they represent a novel class of 8C-hevein-like peptides that are Pro-rich and protein-cargo free. Our findings also suggest that the ginkgotide scaffold could be useful for engineering metabolic-stable peptide therapeutics. PMID:27857717

Ginkgotides: Proline-Rich Hevein-Like Peptides from Gymnosperm Ginkgo biloba.

PubMed

Wong, Ka H; Tan, Wei Liang; Serra, Aida; Xiao, Tianshu; Sze, Siu Kwan; Yang, Daiwen; Tam, James P

2016-01-01

Hevein and hevein-like peptides belong to the family of chitin-binding cysteine-rich peptides. They are classified into three subfamilies, the prototypic 8C- and the 6C- and 10C-hevein-like peptides. Thus far, only five 8C-hevein-like peptides have been characterized from three angiosperms and none from gymnosperm. To determine their occurrence and distribution in the gymnosperm, Ginkgo biloba leaves were examined. Here, we report the discovery and characterization of 11 novel 8C-hevein-like peptides, namely ginkgotides gB1-gB11. Proteomic analysis showed that the ginkgotides contain 41-44 amino acids (aa), a chitin-binding domain and are Pro-rich, a distinguishing feature that differs from other hevein-like peptides. Solution NMR structure determination revealed that gB5 contains a three β-stranded structure shaped by a cystine knot with an additional disulfide bond at the C-terminus. Transcriptomic analysis showed that the ginkgotide precursors contain a three-domain architecture, comprised of a C-terminal tail (20 aa) that is significantly shorter than those of other 8C- and 10C-hevein-like peptides, which generally contain a protein cargo such as a Barwin-like protein (126 aa) or class I chitinase (254 aa). Transcriptomic data mining found an additional 48 ginkgotide homologs in 39 different gymnosperms. Phylogenetic analysis revealed that ginkgotides and their homologs belong to a new class of 8C-hevein-like peptides. Stability studies showed that ginkgotides are highly resistant to thermal, acidic and endopeptidase degradation. Ginkgotides flanked at both the N- and C-terminal ends by Pro were resistant to exopeptidase degradation by carboxypeptidase A and aminopeptidase. Antifungal assays showed that ginkgotides inhibit the hyphal growth of phyto-pathogenic fungi. Taken together, ginkgotides represent the first suite of hevein-like peptides isolated and characterized from gymnosperms. As a group, they represent a novel class of 8C-hevein-like peptides that are Pro-rich and protein-cargo free. Our findings also suggest that the ginkgotide scaffold could be useful for engineering metabolic-stable peptide therapeutics.

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

Li, H.K.; Science Center for Phase Diagram and Materials Design and Manufacture, Central South University, Changsha, Hunan 410083; Cai, G.M., E-mail: caigemei@csu.edu.cn

Two novel borate compounds MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8}, have been synthesized via solid-state reactions, and their crystal structures have been solved and refined from powder X-ray diffraction data. The compound MgInBO{sub 4}, which was obtained at 1190 °C, belongs to the warwickite family. It crystallizes in the Pnma space group (no. 62) with a=9.5443(1) Å, b=3.2771(1) Å, c=9.5228(1) Å, and Z=4. The fundamental building units are liner –Mg(In)O{sub 6}–[In(Mg)]{sub 2}O{sub 10}–Mg(In)O{sub 6}– chains and isolated BO{sub 3} triangles. The low-temperature phase, MgIn{sub 7/8}B{sub 7/8}O{sub 29/8}, whose crystal structure is solved ab initio by the charge-flipping method withmore » standard chemical formula MgInBO{sub 4}, was prepared at 1080 °C. It crystallizes in the P12{sub 1}/n1 space group (no. 14) with a=17.0976(1) Å, b=3.2504(1) Å, c=5.3387(1) Å, β=96.0829(3)°, and Z=4. The structure of MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} contains [In(2)/Mg(2)]{sub 2}O{sub 10} groups, –MgO{sub 6}–InO{sub 6}– infinite ribbons and isolated BO{sub 3} triangles. The experiments and the differential thermal analysis (DTA) show the decompositions of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} happen at about 1220 °C and 1180 °C, respectively. The comparative crystal chemistry from MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} to MgInBO{sub 4} has been discussed. Infrared spectra and UV–vis diffuse reflectance spectra of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} were measured. - Graphical abstract: The structural transformation from the monoclinic MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} (P12{sub 1}/n1) to the orthorhombic MgInBO{sub 4} (Pnma). - Highlights: • Two novel borate compounds MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} have been synthesized via solid-state reactions for the first time. • The crystal structures of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} have been solved and refined from powder X-ray diffraction data. • The possible crystal chemical analysis from MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} to MgInBO{sub 4} is discussed. • Infrared spectra and UV–vis diffuse reflectance spectra of MgInBO{sub 4} and MgIn{sub 7/8}B{sub 7/8}O{sub 29/8} have been measured.« less

X-ray structural investigation of nonsymmetrically and symmetrically alkylated [1]benzothieno[3,2-b]benzothiophene derivatives in bulk and thin films.

PubMed

Gbabode, Gabin; Dohr, Michael; Niebel, Claude; Balandier, Jean-Yves; Ruzié, Christian; Négrier, Philippe; Mondieig, Denise; Geerts, Yves H; Resel, Roland; Sferrazza, Michele

2014-08-27

A detailed structural study of the bulk and thin film phases observed for two potential high-performance organic semiconductors has been carried out. The molecules are based on [1]benzothieno[3,2-b]benzothiophene (BTBT) as conjugated core and octyl side groups, which are anchored either symmetrically at both sides of the BTBT core (C8-BTBT-C8) or nonsymmetrically at one side only (C8-BTBT). Thin films of different thickness (8-85 nm) have been prepared by spin-coating for both systems and analyzed by combining specular and grazing incidence X-ray diffraction. In the case of C8-BTBT-C8, the known crystal structure obtained from single-crystal investigations is observed within all thin films, down to a film thickness of 9 nm. In the case of C8-BTBT, the crystal structure of the bulk phase has been determined from X-ray powder diffraction data with a consistent matching of experimental and calculated X-ray diffraction patterns (Rwp = 5.8%). The packing arrangement of C8-BTBT is similar to that of C8-BTBT-C8, that is, consisting of a lamellar structure with molecules arranged in a "herringbone" fashion, yet with lamellae composed of two head-to-head (or tail-to-tail as the structure is periodic) superimposed molecules instead of only one molecule for C8-BTBT-C8. As for C8-BTBT-C8, we demonstrate that the same phase is observed in bulk and thin films for C8-BTBT whatever the film thickness investigated.

Investigation on mechanical behavior and material characteristics of various weight composition of SiCp reinforced aluminium metal matrix composite

NASA Astrophysics Data System (ADS)

Pichumani, Sivachidambaram; Srinivasan, Raghuraman; Ramamoorthi, Venkatraman

2018-02-01

Aluminium - silicon carbide (Al - SiC) metal matrix composite is produced with following wt % of SiC reinforcement (4%, 8% & 12%) using stir casting method. Mechanical testing such as micro hardness, tensile testing and bend testing were performed. Characterizations, namely micro structure, X-ray diffraction (XRD) analysis, inductive coupled plasma - optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM) analysis, were carried out on Al - SiC composites. The presence of SiC on Al - SiC composite is confirmed through XRD technique and microstructure. The percentage of SiC was confirmed through ICP-OES technique. Increase in weight percentage of SiC tends to increase micro hardness, ultimate strength & yield strength but it reduces the bend strength and elongation (%) of the material. SEM factrography of tensile tested fractured samples of Al - 8% SiC & Al - 12% SiC showed fine dimples on fractured surface & coarse dimples fractured surface respectively. This showed significant fracture differences between Al - 8% SiC & Al - 12% SiC. From the above experiment, Al - 8% SiC had good micro hardness, ultimate strength & yield strength without significant loss in elongation (%) & bend strength.

Examining the factor structure of MUIS-C scale among baby boomers with hepatitis C.

PubMed

Reinoso, Humberto; Türegün, Mehmet

2016-11-01

Baby boomers account for two out of every three cases of hepatitis C infection in the U.S. To conduct an exploratory factor analysis directed at supporting the use of the MUIS-C as a reliable instrument in measuring illness uncertainty among baby boomers with hepatitis C. The steps of conducting a typical principal component analysis (PCA) with an oblique rotation were used on a sample of 146 participants, the sampling adequacy of items was examined via the Kaiser-Meyer-Olkin (KMO) measure, and the Bartlett's sphericity test was used for appropriateness of conducting a factor analysis. A two-factor structure was obtained by using Horn's parallel analysis method. The two factors explained a cumulative total of 45.8% of the variance. The results of the analyses indicated that the MUIS-C was a valid and reliable instrument and potentially suitable for use in baby boomer population diagnosed with hepatitis C. Published by Elsevier Inc.

Design Study of 8 Meter Monolithic Mirror UV/Optical Space Telescope

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2008-01-01

The planned Ares V launch vehicle with its 10 meter fairing shroud and 55,000 kg capacity to the Sun Earth L2 point enables entirely new classes of space telescopes. NASA MSFC has conducted a preliminary study that demonstrates the feasibility of launching a 6 to 8 meter class monolithic primary mirror telescope to Sun-Earth L2 using an Ares V. Specific technical areas studied included optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; launch vehicle performance and trajectory; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; operations and servicing; mass and power budgets; and system cost.

Structure elucidation and chemical synthesis of stigmolone, a novel type of prokaryotic pheromone.

PubMed

Hull, W E; Berkessel, A; Plaga, W

1998-09-15

Approximately 2 micromol of a novel prokaryotic pheromone, involved in starvation-induced aggregation and formation of fruiting bodies by the myxobacterium Stigmatella aurantiaca, were isolated by a large-scale elution procedure. The pheromone was purified by HPLC, and high-resolution MS, IR, 1H-NMR, and 13C-NMR were used to identify the active substance as the hydroxy ketone 2,5, 8-trimethyl-8-hydroxy-nonan-4-one, which has been named stigmolone. The analysis was complicated by a solvent-dependent equilibrium between stigmolone and the cyclic enol-ether 3,4-dihydro-2,2, 5-trimethyl-6-(2-methylpropyl)-2H-pyran formed by intramolecular nucleophilic attack of the 8-OH group at the ketone C4 followed by loss of H2O. Both compounds were synthesized chemically, and their structures were confirmed by NMR analysis. Natural and synthetic stigmolone have the same biological activity at ca. 1 nM concentration.

Synthesis, magnetic and electrical properties of R3AlCx (R = Ce, Pr and Nd)

NASA Astrophysics Data System (ADS)

Ghule, S. S.; Garde, C. S.; Ramakrishnan, S.; Singh, S.; Rajarajan, A. K.; Laad, Meena; Karmakar, Koushik

2017-09-01

R3AlCx (R = Ce, Pr and Nd; x = 0-1) series has been synthesized by arc melting. Rietveld analysis of x-ray powder diffraction reveals cubic (Pm-3m) structure. A Kondo temperature TK 1 K is estimated for Ce3AlC0.65 from the susceptibility and resistivity data. Magnetic susceptibility measurements indicate antiferromagnetic (AFM) order for R = Pr (x = 0.8 and 1) and Nd (x = 0.6, 0.8 and 1) and ferromagnetic (FM) for Nd3Al. Metamagnetic behaviour in the magnetization curve indicates complex magnetic structure. Band structure calculations indicate growth of a pseudo-gap in the density of states (DOS) from Ce3AlC to Pr3AlC to Nd3AlC. The DOS calculations predict a metallic behaviour which is consistent with the resistivity measurements.

Novel dimeric metabolites from Alternaria tagetica.

PubMed

Gamboa-Angulo, M M; Alejos-González, F; Escalante-Erosa, F; García-Sosa, K; Delgado-Lamas, G; Peña-Rodríguez, L M

2000-08-01

Two novel polyketides, bis-7-O-8' '.8-O-7' '- and bis-7-O-7' '. 8-O-8' '-zinniol (2 and 3, respectively) were isolated from the organic crude extract of culture filtrates from Alternaria tagetica. Both structures were determined on the basis of their spectroscopic data (IR, MS, (1)H NMR, (13)C NMR, and 2D NMR experiments) and confirmed by chemical synthesis. Zinniol (1) was isolated as a major component, and its (13)C NMR data was correctly assigned after careful analysis of data from its 2D NMR experiments (HMQC and HMBC).

Biochemical characterization of Yarrowia lipolytica LIP8, a secreted lipase with a cleavable C-terminal region.

PubMed

Kamoun, Jannet; Schué, Mathieu; Messaoud, Wala; Baignol, Justine; Point, Vanessa; Mateos-Diaz, Eduardo; Mansuelle, Pascal; Gargouri, Youssef; Parsiegla, Goetz; Cavalier, Jean-François; Carrière, Frédéric; Aloulou, Ahmed

2015-02-01

Yarrowia lipolytica is a lipolytic yeast possessing 16 paralog genes coding for lipases. Little information on these lipases has been obtained and only the major secreted lipase, namely YLLIP2, had been biochemically and structurally characterized. Another secreted lipase, YLLIP8, was isolated from Y. lipolytica culture medium and compared with the recombinant enzyme produced in Pichia pastoris. N-terminal sequencing showed that YLLIP8 is produced in its active form after the cleavage of a signal peptide. Mass spectrometry analysis revealed that YLLIP8 recovered from culture medium lacks a C-terminal part of 33 amino acids which are present in the coding sequence. A 3D model of YLLIP8 built from the X-ray structure of the homologous YLLIP2 lipase shows that these truncated amino acids in YLLIP8 belong to an additional C-terminal region predicted to be mainly helical. Western blot analysis shows that YLLIP8 C-tail is rapidly cleaved upon enzyme secretion since both cell-bound and culture supernatant lipases lack this extension. Mature recombinant YLLIP8 displays a true lipase activity on short-, medium- and long-chain triacylglycerols (TAG), with an optimum activity at alkaline pH on medium chain TAG. It has no apparent regioselectivity in TAG hydrolysis, thus generating glycerol and FFAs as final lipolysis products. YLLIP8 properties are distinct from those of the 1,3-regioselective YLLIP2, acting optimally at acidic pH. These lipases are tailored for complementary roles in fatty acid uptake by Y. lipolytica. Copyright © 2014 Elsevier B.V. All rights reserved.

Conformation and structure of 3-methoxyphenyl-salicylaldimine

NASA Astrophysics Data System (ADS)

Elmali, A.; Kabak, M.; Elerman, Y.

1999-06-01

3-methoxyphenyl-salicylaldimine (C 14H 13NO 2) was studied by X-ray analysis and AM1 molecular orbital methods. It crystallises in the monoclinic space group P2 1/c with a=20.486(4) Å, b=4.7935(8) Å Å, c=12.310(5) Å, β=107.43(2)°, V=1153.3(6) Å 3, Z=4, D 0=1.309 g cm -3, Z=4, and μ(MoK α)=0.088 mm -1. The structure was solved by direct methods and refined to R=0.033 for 1635 reflections [ I<2(( I)]. The title molecule was nearly planar. There was a strong intramolecular hydrogen bond of distance 2.598(2) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformations from AM1 were calculated as a function of the three torsion angles θ1(C8-N1-C7-C6), θ2(N1-C7-C6-C5), and θ3(C9-C8-N1-C7) varied every 10°. The theoretical calculations were carried out to compare with experimental results of the molecular conformations. The optimized geometry of the crystal structure corresponding to a non-planar conformation is the most stable conformation in all theoretical calculations.

Crystal Structure of the MACPF Domain of Human Complement Protein C8[alpha] in Complex with the C8[gamma] Subunit

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

Slade, Daniel J.; Lovelace, Leslie L.; Chruszcz, Maksymilian

2010-03-04

Human C8 is one of five complement components (C5b, C6, C7, C8, and C9) that assemble on bacterial membranes to form a porelike structure referred to as the 'membrane attack complex' (MAC). C8 contains three genetically distinct subunits (C8{alpha}, C8{beta}, C8{gamma}) arranged as a disulfide-linked C8{alpha}-{gamma} dimer that is noncovalently associated with C8{beta}. C6, C7 C8{alpha}, C8{beta}, and C9 are homologous. All contain N- and C-terminal modules and an intervening 40-kDa segment referred to as the membrane attack complex/perforin (MACPF) domain. The C8{gamma} subunit is unrelated and belongs to the lipocalin family of proteins that display a {beta}-barrel fold andmore » generally bind small, hydrophobic ligands. Several hundred proteins with MACPF domains have been identified based on sequence similarity; however, the structure and function of most are unknown. Crystal structures of the secreted bacterial protein Plu-MACPF and the human C8{alpha} MACPF domain were recently reported and both display a fold similar to those of the bacterial pore-forming cholesterol-dependent cytolysins (CDCs). In the present study, we determined the crystal structure of the human C8{alpha} MACPF domain disulfide-linked to C8{gamma} ({alpha}MACPF-{gamma}) at 2.15 {angstrom} resolution. The {alpha}MACPF portion has the predicted CDC-like fold and shows two regions of interaction with C8{gamma}. One is in a previously characterized 19-residue insertion (indel) in C8{alpha} and fills the entrance to the putative C8{gamma} ligand-binding site. The second is a hydrophobic pocket that makes contact with residues on the side of the C8{gamma} {beta}-barrel. The latter interaction induces conformational changes in {alpha}MACPF that are likely important for C8 function. Also observed is structural conservation of the MACPF signature motif Y/W-G-T/S-H-F/Y-X{sub 6}-G-G in {alpha}MACPF and Plu-MACPF, and conservation of several key glycine residues known to be important for refolding and pore formation by CDCs.« less

Structural analysis of benzothienobenzothiophene-based soluble organic semiconducting crystals grown by liquid crystal solvent

NASA Astrophysics Data System (ADS)

Shibata, Yosei; Matsuzaki, Tomoya; Ishinabe, Takahiro; Fujikake, Hideo

2018-06-01

In this study, we analyzed organic semiconducting single crystals composed of benzothienobenzothiophene derivatives (2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene, C8-BTBT) grown by nematic-phase liquid crystal (LC) solvent. As a result, we clarified that the crystal b-axis direction of the C8-BTBT single crystals was consistent with the LC alignment direction. By optical evaluation and simulation based on density functional theory, we found that the C8-BTBT single crystals in LC solvent exhibited a novel molecular conformation having alkyl chains oriented toward the b-axis.

Bisabolane-type sesquiterpenes from the aerial parts of Lippia dulcis.

PubMed

Ono, Masateru; Tsuru, Tsuyoshi; Abe, Hiroaki; Eto, Masashi; Okawa, Masafumi; Abe, Fumiko; Kinjo, Junei; Ikeda, Tsuyoshi; Nohara, Toshihiro

2006-10-01

Six new bisabolane-type sesquiterpenes, peroxylippidulcines A-C (3-5), peroxyepilippidulcine B (6), and epilippidulcines B (7) and C (8), have been isolated from the aerial parts of Lippia dulcis, along with two known bisabolane-type sesquiterpenes, seven known flavonoids, and a known triterpenoid. The structures of 3-8 were characterized on the basis of NMR, MS, specific rotation, and X-ray crystallographic analysis data and chemical evidence.

Crystal structures, Hirshfeld surface analysis, thermal behavior and dielectric properties of a new organic-inorganic hybrid [C6H10(NH3)2]Cu2Cl8

NASA Astrophysics Data System (ADS)

Salah, Najet; Hamdi, Besma; Bouzidia, Nabaa; Salah, Abdelhamid Ben

2017-12-01

A novel organic-inorganic hybrid sample [C6H10(NH3)2]Cu2Cl8 has been prepared under mild hydrothermal conditions and characterized by single crystal X-ray diffraction, Hirshfeld surface analysis, FT-IR,NMR and UV-Vis spectroscopies, differential scanning calorimetric and dielectric measurement. It is crystallized in the monoclinic system with P21/c space group. The cohesion and stabilization of the structure are provided by the hydrogen bond interactions, (Nsbnd H⋯Cl and Csbnd H⋯Cl), between [C6H10(NH3)2]2+ cation and [Cu2Cl8]2- anion. The Hirschfeld surface analysis has been performed to explore the behavior of these weak interactions. The presence of different functional groups and the nature of their vibrations were identified by FT-IR and Solid state NMR. The thermal study revealed that this compound undergoes two structural phase transitions around 353 and 376 K. Electrical measurements of our compounds have been investigated using complex impedance spectroscopy (CIS) in the frequency and temperature range 331-399 K and 200 Hz-5 MHz, respectively. The AC conductivity is explained using the correlated barrier hopping model (CBH) conduction mechanism. The nature of DC conductivity variation suggests Arrhenius type of electrical conductivity. A relationship between crystal structure and ionic conductivity was established and discussed. Finally, the real and imaginary parts of the permittivity constant are analyzed with the Cole-Cole formalism and the optical spectra indicate that the compound has a direct band gap (3.14 eV) due to direct transition. The wide band gap is due to low defect concentration in the grown crystal, which is more useful for the laser/optical applications.

Structure-function analysis of myomaker domains required for myoblast fusion.

PubMed

Millay, Douglas P; Gamage, Dilani G; Quinn, Malgorzata E; Min, Yi-Li; Mitani, Yasuyuki; Bassel-Duby, Rhonda; Olson, Eric N

2016-02-23

During skeletal muscle development, myoblasts fuse to form multinucleated myofibers. Myomaker [Transmembrane protein 8c (TMEM8c)] is a muscle-specific protein that is essential for myoblast fusion and sufficient to promote fusion of fibroblasts with muscle cells; however, the structure and biochemical properties of this membrane protein have not been explored. Here, we used CRISPR/Cas9 mutagenesis to disrupt myomaker expression in the C2C12 muscle cell line, which resulted in complete blockade to fusion. To define the functional domains of myomaker required to direct fusion, we established a heterologous cell-cell fusion system, in which fibroblasts expressing mutant versions of myomaker were mixed with WT myoblasts. Our data indicate that the majority of myomaker is embedded in the plasma membrane with seven membrane-spanning regions and a required intracellular C-terminal tail. We show that myomaker function is conserved in other mammalian orthologs; however, related family members (TMEM8a and TMEM8b) do not exhibit fusogenic activity. These findings represent an important step toward deciphering the cellular components and mechanisms that control myoblast fusion and muscle formation.

Conformational analysis of α-helical polypeptide included L-proline residue by high-resolution solid-state NMR measurement and quantum chemical calculation

NASA Astrophysics Data System (ADS)

Souma, Hiroyuki; Shoji, Akira; Kurosu, Hiromichi

2008-10-01

We challenged the problem about the stabilization mechanism of an α-helix formation for polypeptides containing L-proline (Pro) residue. We computed the optimized structure of α-helical poly( L-alanine) molecules including a Pro residue, H-(Ala) 8-Pro-(Ala) 9-OH, based on the molecular orbital calculation with density functional theory, B3LYP/6-31G(d) and the 13C and 15N chemical shift values based on the GIAO-CHF method with B3LYP/6-311G(d,p), respectively. It was found that two kinds of optimized structures, 'Bent structure' and 'Included α-helix structure', were preferred structures in H-(Ala) 8-Pro-(Ala) 9-OH. In addition, based on the precise 13C and 15N chemical shift data of the simple model, we successfully analyzed the secondary structure of well-defined synthetic polypeptide H-(Phe-Leu-Ala) 3-Phe C-Pro-Ala N-(Phe-Leu-Ala) 2-OH (FLA-11P), the secondary structure of which was proven to the 'Included α-helix structure'.

A Saturn-Like Complex Composed of Macrocyclic Oligothiophene and C60 Fullerene: Structure, Stability, and Photophysical Properties in Solution and the Solid State.

PubMed

Shimizu, Hideyuki; Park, Kyu Hyung; Otani, Hiroyuki; Aoyagi, Shinobu; Nishinaga, Tohru; Aso, Yoshio; Kim, Dongho; Iyoda, Masahiko

2018-03-12

A Saturn-like 1:1 complex composed of macrocyclic oligothiophene E-8T7A and C 60 fullerene (C 60 ) was synthesized to investigate the interaction between macrocyclic oligothiophenes and C 60 in solution and the solid state. Because the Saturn-like 1:1 complex E-8T7A⋅C 60 is mainly stabilized by van der Waals interactions between C 60 and the sulfur atoms of the E-8T7A macrocycle, C 60 is rather weakly incorporated inside the macro-ring in solution. However, in the solid state the Saturn-like 1:1 complex preferentially formed single crystals or nanostructured polymorphs. Interestingly, X-ray analysis and theoretical calculations exhibited hindered rotation of C 60 in the Saturn-like complex due to interactions between C 60 and the sulfur atoms. Furthermore, the photoinduced charge transfer (CT) interaction between E-8T7A and C 60 in solution was investigated by using femtosecond transient absorption (TA) spectroscopy. The ultrafast TA spectral changes in the photoinduced absorption bands were attributed to the CT process in the Saturn-like structure. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A sodium gadolinium phosphate with two different types of tunnel structure: Synthesis, crystal structure, and optical properties of Na 3GdP 2O 8

NASA Astrophysics Data System (ADS)

Fang, M.; Cheng, W.-D.; Zhang, H.; Zhao, D.; Zhang, W.-L.; Yang, S.-L.

2008-09-01

A sodium gadolinium phosphate crystal, Na 3GdP 2O 8, has been synthesized by a high-temperature solution reaction, and it exhibits a new structural family of the alkali-metal-rare-earth phosphate system. Although many compounds with formula M 3LnP 2O 8 have been reported, but they were shown to be orthorhombic [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] rather than monoclinic as shown in this paper. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group C2/ c and the cell parameters: a=27.55 (25), b=5.312 (4), c=13.935(11) Å, β=91.30(1)°, and V=2038.80 Å 3, Z=4. Its structure features a three-dimensional GdP 2O 83- anionic framework with two different types of interesting tunnels at where Na atoms are located by different manners. The framework is constructed by Gd polyhedra and isolated PO 4 tetrahedra. It is different from the structure of K 3NdP 2O 8 [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] with space group P2 1/ m that shows only one type of tunnel. The emission spectrum and the absorption spectrum of the compound have been investigated. Additionally, the calculations of band structure, density of states, dielectric constants, and refractive indexes have been also performed with the density functional theory method. The obtained results tend to support the experimental data.

Relaxations of fluorouracil tautomers by decorations of fullerene-like SiCs: DFT studies

NASA Astrophysics Data System (ADS)

Kouchaki, Alireza; Gülseren, Oğuz; Hadipour, Nasser; Mirzaei, Mahmoud

2016-06-01

Decorations of silicon carbide (SiC) fullerene-like nanoparticles by fluorouracil (FU) and its tautomers are investigated through density functional theory (DFT) calculations. Two models of fullerene-like particles including Si12C8 and Si8C12 are constructed to be counterparts of decorated hybrid structures, FU@Si12C8 and FU@Si8C12, respectively. The initial models including original FU and tautomeric structures and SiC nanoparticles are individually optimized and then combined for further optimizations in the hybrid forms. Covalent bonds are observed for FU@Si12C8 hybrids, whereas non-covalent interactions are seen for FU@Si8C12 ones. The obtained properties indicated that Si12C8 model could be considered as a better counterpart for interactions with FU structures than Si8C12 model. The results also showed significant effects of interactions on the properties of atoms close to the interacting regions in nanoparticles. Finally, the tautomeric structures show different behaviors in interactions with SiC nanoparticles, in which the SiC nanoparticles could be employed to detect the situations of tautomeric processes for FU structures.

Approximate Fluid-Structure Interaction Theories for Acoustic Echo Signal Predictions.

DTIC Science & Technology

1981-10-19

mations for Structure-Fluid Interaction Analysis," PA,,e𔃻n:s the Second International Symposium on Tnnovative Nijm,r;-a’ An.ti si in Applied ... Engineering Science, Montreal, Canada, June !,150, pi. 79-88. 8. Junger, M.C. and Feit, D., Sound. Structures and tht ir Tu,>i the MIT Press, Cambridge, MA

Hydrothermal synthesis, crystal structures, and enantioselective adsorption property of bis(L-histidinato)nickel(II) monohydrate

NASA Astrophysics Data System (ADS)

Ramos, Christian Paul L.; Conato, Marlon T.

2018-05-01

Despite the numerous researches in metal-organic frameworks (MOFs), there are only few reports on biologically important amino acids, histidine in particular, on its use as bridging ligand in the construction of open-framework architectures. In this work, hydrothermal synthesis was used to prepare a compound based on Ni2+ and histidine. The coordination assembly of imidazole side chain of histidine with divalent nickel ions in aqueous condition yielded purple prismatic solids. Single crystal X-ray diffraction (XRD) analysis of the product revealed structure for Ni(C6H8N3O2)2 • H2O that has a monoclinic (C2) structure with lattice parameters, a = 29.41, b = 8.27, c = 6.31 Å, β = 90.01 ˚. Circular dichroism - optical rotatory dispersion (CD-ORD), Powder X-ray diffraction (PXRD) and Fourier transform - infrared spectroscopy (FT-IR) analyses are conducted to further characterize the crystals. Enantioselective adsorption analysis using racemic mixture of 2-butanol confirmed bis(L-histidinato)nickel(II) monohydrate MOF crystal's enantioselective property preferentially favoring the adsorption of (S)-2-butanol isomer.

Crystal structure, conformational analysis, and molecular dynamics of tetra-0-methyl-(+)-catechin

Treesearch

Frank R. Fronczek; Richard W. Hemingway; G. Wayne McGraw; Jan P. Steynberg; Carin A. Helfer; Wayne L. Mattice

1993-01-01

The structure of tetra-O-methyl-(+)-catechin has been determined in the crystalline state. Two independent molecules, denoted structure A and structure B, exist in the unit cell. Crystals are triclinic, space group P1, a=4.8125(2) Ǻ, b=12.9148(8) Ǻ, c=13.8862(11) Ǻ, α=86.962(6)°, β=89.120(5)°, γ=...

Interfacial Electronic Structures of Photodetectors Based on C8BTBT/Perovskite.

PubMed

Li, Lin; Tong, Sichao; Zhao, Yuan; Wang, Can; Wang, Shitan; Lyu, Lu; Huang, Yingbao; Huang, Han; Yang, Junliang; Niu, Dongmei; Liu, Xiaoliang; Gao, Yongli

2018-06-07

Comprehensive measurements of ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, X-ray diffraction, and atomic force microscopy are adopted to investigate the corelevance of energy level alignment, molecular orientation, and film growth of Au/C8BTBT/perovskite interfaces. A small energy offset of valence band maximum of 0.06 eV between perovskite and C8BTBT makes hole transportation feasible. About 0.65 eV upward shift of energy levels is observed with the deposition of the Au film on C8BTBT, which enhances hole transportation to the Au electrode. The observations from the interface analysis are supported by a prototype photodetector of Au (80 nm)/C8BTBT (20 nm)/perovskite (100 nm) that exhibits excellent performances whose responsivity can reach up to 2.65 A W -1 , 4 times higher than the best CH 3 NH 3 PbI 3 photodetectors.

Experimental (FTIR, Raman, UV-visible and PL) and theoretical (DFT and TDDFT) studies on bis(8-hydroxyquinolinium) tetrachlorocobaltate(II) compound

NASA Astrophysics Data System (ADS)

Chaouachi, Soumaya; Elleuch, Slim; Hamdi, Besma; Zouari, Ridha

2016-12-01

The purpose of this paper is to present the chemical preparation, crystal structure, vibrational study and optical features for new organic-inorganic compound [C9H8NO]2CoCl4 abbreviated [8-HQ]2CoCl4. The structural study by X-ray diffraction prove that this compound crystallize in a monoclinic unit-cell with space group C2/c (point group 2/m = C2h). It is built of tetrahedra [CoCl4]2- anions and (C9H8NO)+ cations in the 1/2 ratio. The crystal structure is stabilized by network three-dimensional of Nsbnd H⋯Cl, Nsbnd H⋯O, Osbnd H⋯Cl, Csbnd H⋯Cl hydrogen bonds, and offset π-π stacking interactions. Also, the Hirshfeld Surface projections and Fingerprint plots were elucidated the relative contribution of the type, nature and explore the H⋯Cl, C⋯H, C⋯C, C⋯N, H⋯O intermolecular contacts in the crystal in a visual manner. Furthermore, vibrational analysis of the structural groups in the compound was carried out by both Fourier transforms infrared (FT-IR) and Raman spectra. The spectral data are complemented by good information at the region characteristic of metal-ligand, which evidences coordination through the compound. The optical properties of the crystal were studied by using optical absorption UV-visible and photoluminescence (PL) spectroscopy studies. Theoretical calculations were performed using density functional theory (DFT) at (DFT/B3LYP/LanL2DZ) level in the aim of aiding in studying structural, vibrational and optical properties of the investigated compound. Good relationship consistency is found between the experimental and theoretical studies. Inspection of the optical properties has lead to confirm the exhibition of a green photoluminescence and the occurrence of charge transfer phenomenon in this material.

Stochastic-Strength-Based Damage Simulation of Ceramic Matrix Composite Laminates

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Mital, Subodh K.; Murthy, Pappu L. N.; Bednarcyk, Brett A.; Pineda, Evan J.; Bhatt, Ramakrishna T.; Arnold, Steven M.

2016-01-01

The Finite Element Analysis-Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program was used to characterize and predict the progressive damage response of silicon-carbide-fiber-reinforced reaction-bonded silicon nitride matrix (SiC/RBSN) composite laminate tensile specimens. Studied were unidirectional laminates [0] (sub 8), [10] (sub 8), [45] (sub 8), and [90] (sub 8); cross-ply laminates [0 (sub 2) divided by 90 (sub 2),]s; angled-ply laminates [plus 45 (sub 2) divided by -45 (sub 2), ]s; doubled-edge-notched [0] (sub 8), laminates; and central-hole laminates. Results correlated well with the experimental data. This work was performed as a validation and benchmarking exercise of the FEAMAC/CARES program. FEAMAC/CARES simulates stochastic-based discrete-event progressive damage of ceramic matrix composite and polymer matrix composite material structures. It couples three software programs: (1) the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC), (2) the Ceramics Analysis and Reliability Evaluation of Structures Life Prediction Program (CARES/Life), and (3) the Abaqus finite element analysis program. MAC/GMC contributes multiscale modeling capabilities and micromechanics relations to determine stresses and deformations at the microscale of the composite material repeating-unit-cell (RUC). CARES/Life contributes statistical multiaxial failure criteria that can be applied to the individual brittle-material constituents of the RUC, and Abaqus is used to model the overall composite structure. For each FEAMAC/CARES simulation trial, the stochastic nature of brittle material strength results in random, discrete damage events that incrementally progress until ultimate structural failure.

Structural study of dehydration mechanisms of NH4Th(NO3)5·9H2O

NASA Astrophysics Data System (ADS)

Knyazev, A. V.; Komshina, M. E.; Baranov, E. V.; Savushkin, I. A.; Nipruk, O. V.; Lukoyanov, A. Yu.

2017-12-01

The new pentanitrate thorium compounds NH4Th(NO3)5·nH2O were synthesized and their crystal structures were determined by X-ray diffraction analysis: space group P21/n, a = 10.5476(5), b = 14.0444(7), c = 15.5287(8) Å, β = 109.4999(7)°, Z = 4; R = 0.0246 (NH4Th(NO3)5·9H2O); space group P212121, a = 8.7039(4), b = 11.9985(6), c = 16.3531(8) Å, Z = 4; R = 0.0259 (NH4Th(NO3)5·5H2O). Features of structural changes in the dehydration were revealed. Conditions of thermal decomposition of the thorium compound were established using differential scanning calorimetry. The compound was investigated by IR spectroscopy and its bands are assigned.

Effective virtual screening protocol for CYP2C9 ligands using a screening site constructed from flurbiprofen and S-warfarin pockets

NASA Astrophysics Data System (ADS)

Polgár, Tímea; Menyhárd, Dóra K.; Keserű, György M.

2007-09-01

An effective virtual screening protocol was developed against an extended active site of CYP2C9, which was derived from X-ray structures complexed with flubiprofen and S-warfarin. Virtual screening has been effectively supported by our structure-based pharmacophore model. Importance of hot residues identified by mutation data and structural analysis was first estimated in an enrichment study. Key role of Arg108 and Phe114 in ligand binding was also underlined. Our screening protocol successfully identified 76% of known CYP2C9 ligands in the top 1% of the ranked database resulting 76-fold enrichment relative to random situation. Relevance of the protocol was further confirmed in selectivity studies, when 89% of CYP2C9 ligands were retrieved from a mixture of CYP2C9 and CYP2C8 ligands, while only 22% of CYP2C8 ligands were found applying the structure-based pharmacophore constraints. Moderate discrimination of CYP2C9 ligands from CYP2C18 and CYP2C19 ligands could also be achieved extending the application domain of our virtual screening protocol for the entire CYP2C family. Our findings further demonstrate the existence of an active site comprising of at least two binding pockets and strengthens the need of involvement of protein flexibility in virtual screening.

An Improved Analysis of the Sevoflurane-Benzene Structure by Chirped Pulse Ftmw Spectroscopy

NASA Astrophysics Data System (ADS)

Seifert, Nathan A.; Perez, Cristobal; Zaleski, Daniel P.; Neill, Justin L.; Pate, Brooks H.; Lesarri, Alberto; Vallejo, Montserrat; Cocinero, Emilio J.; Castano, Fernando; Kleiner, Isabelle

2013-06-01

Recent improvements to the 2-8 GHz CP-FTMW spectrometer at University of Virginia have improved the structural and spectroscopic analysis of the sevoflurane-benzene cluster. Previously reported results, although robust, were limited to a fit of the a-type transitions of the normal species in the determination of the six-fold barrier to benzene internal rotation. Structural analysis was limited to the benzene hydrogen atom positions using benzene-d_{1}. The increased sensitivity of the new 2-8 GHz setup allows for a full internal rotation analysis of the a- and c-type transitions of the normal species, which was performed with BELGI. A fit value for V_{6} of 32.868(11) cm^{-1} is determined. Additionally, a full substitution structure of the benzene carbon atom positions was determined in natural abundance. Also, new measurements of a sevoflurane/benzene-d_{1} mixture enabled detection of 33 of the 60 possible ^{2}D / ^{13}C double isotopologues. This abundance of isotopic data, a total of 45 isotopologues, enabled a full heavy atom least-squares r_{0} structure fit for the complex, including positions for all seven fluorines in sevoflurane. N. A. Seifert, D. P. Zaleski, J. L. Neill, B. H. Pate, A. Lesarri, M. Vallejo, E. J. Cocinero, F. Castańo. 67th OSU Int. Symp. On Mol. Spectrosc., Columbus, OH, 2012, MH13.

Phase transition on the Si(001) clean surface prepared in UHV MBE chamber: a study by high-resolution STM and in situ RHEED

PubMed Central

2011-01-01

The Si(001) surface deoxidized by short annealing at T ~ 925°C in the ultrahigh vacuum molecuar beam epitaxy chamber has been in situ investigated using high-resolution scanning tunneling microscopy (STM)and redegreesected high-energy electron diffraction (RHEED. RHEED patterns corresponding to (2 × 1) and (4 × 4) structures were observed during sample treatment. The (4 × 4) reconstruction arose at T ≲ 600°C after annealing. The reconstruction was observed to be reversible: the (4 × 4) structure turned into the (2 × 1) one at T ≳ 600°C, the (4 × 4) structure appeared again at recurring cooling. The c(8 × 8) reconstruction was revealed by STM at room temperature on the same samples. A fraction of the surface area covered by the c(8 × 8) structure decreased, as the sample cooling rate was reduced. The (2 × 1) structure was observed on the surface free of the c(8 × 8) one. The c(8 × 8) structure has been evidenced to manifest itself as the (4 × 4) one in the RHEED patterns. A model of the c(8 × 8) structure formation has been built on the basis of the STM data. Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed. PACS 68.35.B-·68.37.Ef·68.49.Jk·68.47.Fg PMID:21711733

Structure elucidation and chemical synthesis of stigmolone, a novel type of prokaryotic pheromone

PubMed Central

Hull, William E.; Berkessel, Albrecht; Plaga, Wulf

1998-01-01

Approximately 2 μmol of a novel prokaryotic pheromone, involved in starvation-induced aggregation and formation of fruiting bodies by the myxobacterium Stigmatella aurantiaca, were isolated by a large-scale elution procedure. The pheromone was purified by HPLC, and high-resolution MS, IR, 1H-NMR, and 13C-NMR were used to identify the active substance as the hydroxy ketone 2,5,8-trimethyl-8-hydroxy-nonan-4-one, which has been named stigmolone. The analysis was complicated by a solvent-dependent equilibrium between stigmolone and the cyclic enol-ether 3,4-dihydro-2,2,5-trimethyl-6-(2-methylpropyl)-2H-pyran formed by intramolecular nucleophilic attack of the 8-OH group at the ketone C4 followed by loss of H2O. Both compounds were synthesized chemically, and their structures were confirmed by NMR analysis. Natural and synthetic stigmolone have the same biological activity at ca. 1 nM concentration. PMID:9736725

A blue corrinoid from partial degradation of vitamin B12 in aqueous bicarbonate: spectra, structure, and interaction with proteins of B12 transport.

PubMed

Fedosov, Sergey N; Ruetz, Markus; Gruber, Karl; Fedosova, Natalya U; Kräutler, Bernhard

2011-09-20

Cobalamin (Cbl) is a complex cofactor produced only by bacteria but used by all animals and humans. Cyanocobalamin (vitamin B(12), CNCbl) is one commonly isolated form of cobalamin. B(12) belongs to a large group of corrinoids, which are characterized by a distinct red color conferred by the system of conjugated double bonds of the corrin ring retaining a Co(III) ion. A unique blue Cbl derivative was produced by hydrolysis of CNCbl in a weakly alkaline aqueous solution of bicarbonate. This corrinoid was purified and isolated as dark blue crystals. Its spectroscopic analysis and X-ray crystallography revealed B-ring opening with formation of 7,8-seco-cyanocobalamin (7,8-sCNCbl). The unprecedented structural change was caused by cleavage of the peripheral C-C bond between saturated carbons 7 and 8 of the corrin macrocycle accompanied by formation of a C═C bond at C7 and a carbonyl group at C8. Additionally, the C-amide was hydrolyzed to a carboxylic acid. The extended conjugation of the π-system caused a considerable red shift of the absorbance spectrum. Formation and degradation of 7,8-sCNCbl were analyzed qualitatively. Its interaction with the proteins of mammalian Cbl transport revealed both a slow binding kinetics and a low overall affinity. The binding data were compared to those of other monocarboxylic derivatives and agreed with the earlier proposed scheme for two-step ligand recognition. The obtained results are consistent with the structural models of 7,8-sCNCbl and the transport proteins intrinsic factor and transcobalamin. Potential applications of the novel derivative for drug conjugation are discussed. © 2011 American Chemical Society

Structure and conformation of N-(2-methyl-5-chlorophenyl)salicylaldimine

NASA Astrophysics Data System (ADS)

Elmali, A.; Elerman, Y.

1998-02-01

N-(2-methyl-5-chlorophenyl)salicylaldimine (C 14H 12ClNO) has been studied by X-ray analysis and AM1 molecular orbital methods. It crystallises in the orthorhombic space group P2 12 12 1 with a = 7.474(1) Å, b = 12.155(1) Å, c = 13.378(1) Å, V = 1215.3(2) Å3, Z = 4, Dc = 1.343 g cm -3 and μ(Mo Kα) = 0.296 mm -1. The structure was solved by direct methods and refined to R = 0.0374 for 1689 reflections [ I > 2 σ( I)]. The title compound is photochromic and the molecule is not planar. There is a strong intramolecular hydrogen bond of distance 2.604(3) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformations from AM1 were calculated as a function of the three torsion angles θ1(C8N1C7C6), θ2(C9C8N1C7) and θ3(N1C7C6C5), varied every 10°. The optimised geometry of the crystal structure corresponding to a non-planar conformation is the most stable conformation in all calculations.

Dehydration-driven evolution of topological complexity in ethylamonium uranyl selenates

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

Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru; Krivovichev, Sergey V.; Tananaev, Ivan G.

Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules, (C{sub 2}H{sub 8}N){sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}O) (I), (C{sub 2}H{sub 8}N){sub 3}[(UO{sub 2})(SeO{sub 4}){sub 2}(HSeO{sub 4})] (II), (C{sub 2}H{sub 8}N)[(UO{sub 2})(SeO{sub 4})(HSeO{sub 3})] (III), and (C{sub 2}H{sub 8}N)(H{sub 3}O)[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (IV) have been prepared by isothermal evaporation from aqueous solutions. Uranyl-containing 1D and 2D units have been investigated using topological approach and information-based complexity measurements that demonstrate the evolution of structural units and the increase of topological complexity with the decrease of H{sub 2}O content. - Graphical abstract: Single crystals ofmore » four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules have been prepared by isothermal evaporation from aqueous solutions. Structural analysis and information-based topological complexity calculations points to the possible sequence of crystalline phases formation, showing both topological and structural branches of evolution. - Highlights: • Single crystals of four novel uranyl oxysalts were prepared by evaporation method. • The graph theory was used for investigation of topologies of structural units. • Dehydration processes drives the evolution of topological complexity of 1D and 2D structural units.« less

Two human homeobox genes, c1 and c8: structure analysis and expression in embryonic development.

PubMed

Simeone, A; Mavilio, F; Acampora, D; Giampaolo, A; Faiella, A; Zappavigna, V; D'Esposito, M; Pannese, M; Russo, G; Boncinelli, E

1987-07-01

Two human cDNA clones (HHO.c1.95 and HHO.c8.5111) containing a homeobox region have been characterized, and the respective genomic regions have been partially analyzed. Expression of the corresponding genes, termed c1 and c8, was evaluated in different organs and body parts during human embryonic/fetal development. HHO.c1.95 apparently encodes a 217-amino acid protein containing a class I homeodomain that shares 60 out of 61 amino acid residues with the Antennapedia homeodomain of Drosophila melanogaster. HHO.c8.5111 encodes a 153-amino acid protein containing a homeodomain identical to that of the frog AC1 gene. Clones HHO.c1 and HHO.c8 detect by blot-hydridization one and two specific polyadenylylated transcripts, respectively. These are differentially expressed in spinal cord, backbone rudiments, limb buds (or limbs), heart, and skin of human embryos and early fetuses in the 5- to 9-week postfertilization period, thus suggesting that the c1 and c8 genes play a key role in a variety of developmental processes. Together, the results of the embryonic/fetal expression of c1 and c8 and those of two previously analyzed genes (c10 and c13) indicate a coherent pattern of expression of these genes in early human ontogeny.

Fabrication and Properties of Multilayer Structures

DTIC Science & Technology

1983-09-01

according to both the high x-ray count and a Read camera pattern which showed only the 111 8 SiC reflection in a tight ± 30 distribution about the substrate...structural rearrangement. X-ray analysis of the deposited films at the composition of Pd2 Si using a Read camera indicated strong texturing. The...Phys. 35, 547 (1964). 11. C.A. Neubauer and J.R. Randen, Proc. IEEE 52, 1234 (1964). 12. W.A. Tiller, "Fabrication and Properties of Multilayer

Spherical harmonics analysis of surface density fluctuations of spherical ionic SDS and nonionic C12E8 micelles: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Yoshii, Noriyuki; Nimura, Yuki; Fujimoto, Kazushi; Okazaki, Susumu

2017-07-01

The surface structure and its fluctuation of spherical micelles were investigated using a series of density correlation functions newly defined by spherical harmonics and Legendre polynomials based on the molecular dynamics calculations. To investigate the influence of head-group charges on the micelle surface structure, ionic sodium dodecyl sulfate and nonionic octaethyleneglycol monododecylether (C12E8) micelles were investigated as model systems. Large-scale density fluctuations were observed for both micelles in the calculated surface static structure factor. The area compressibility of the micelle surface evaluated by the surface static structure factor was tens-of-times larger than a typical value of a lipid membrane surface. The structural relaxation time, which was evaluated from the surface intermediate scattering function, indicates that the relaxation mechanism of the long-range surface structure can be well described by the hydrostatic approximation. The density fluctuation on the two-dimensional micelle surface has similar characteristics to that of three-dimensional fluids near the critical point.

Spherical harmonics analysis of surface density fluctuations of spherical ionic SDS and nonionic C12E8 micelles: A molecular dynamics study.

PubMed

Yoshii, Noriyuki; Nimura, Yuki; Fujimoto, Kazushi; Okazaki, Susumu

2017-07-21

The surface structure and its fluctuation of spherical micelles were investigated using a series of density correlation functions newly defined by spherical harmonics and Legendre polynomials based on the molecular dynamics calculations. To investigate the influence of head-group charges on the micelle surface structure, ionic sodium dodecyl sulfate and nonionic octaethyleneglycol monododecylether (C 12 E 8 ) micelles were investigated as model systems. Large-scale density fluctuations were observed for both micelles in the calculated surface static structure factor. The area compressibility of the micelle surface evaluated by the surface static structure factor was tens-of-times larger than a typical value of a lipid membrane surface. The structural relaxation time, which was evaluated from the surface intermediate scattering function, indicates that the relaxation mechanism of the long-range surface structure can be well described by the hydrostatic approximation. The density fluctuation on the two-dimensional micelle surface has similar characteristics to that of three-dimensional fluids near the critical point.

Halocin C8: an antimicrobial peptide distributed among four halophilic archaeal genera: Natrinema, Haloterrigena, Haloferax, and Halobacterium.

PubMed

Besse, Alison; Vandervennet, Manon; Goulard, Christophe; Peduzzi, Jean; Isaac, Stéphanie; Rebuffat, Sylvie; Carré-Mlouka, Alyssa

2017-05-01

Halophilic archaea thrive in hypersaline ecosystems and produce antimicrobial peptides (AMPs) named halocins. AMPs are essential effectors of microbial interactions in natural ecosystems. Halocin C8 is a 7.4 kDa peptide produced by Natrinema sp. AS7092. Surrounded by genes involved in regulation and transport, the halC8 gene encodes a precursor, processed into the mature halocin and an immunity protein, protecting the producing strain against its halocin. This feature constitutes a unique property of halocin C8, as known AMPs and their immunity proteins are generally encoded on distinct ORFs in an operon. By complementary in silico and PCR-based approaches, the presence of halC8 in halophilic archaea collected from various parts of the world was evidenced. The full-length halC8 gene is restricted and consistently found in the genomes of strains belonging to the phylogenetically related genera Natrinema and Haloterrigena, along with transport and regulation genes. Functional expression of halC8 was demonstrated by RT-PCR and antimicrobial assays. Active halocin C8 was shown to contain five disulphide bridges, presumably conferring a compact structure resistant to harsh environmental conditions. In other archaeal genera, Haloferax and Halobacterium, genes encoding halocin C8 with diverging immunity protein moiety were evidenced. A phylogenetic analysis of halocin C8 sequences was conducted.

Solid-state NMR detection of 14N-13C dipolar couplings between amino acid side groups provides constraints on amyloid fibril architecture.

PubMed

Middleton, David A

2011-02-01

Solid-state nuclear magnetic resonance (SSNMR) is a powerful technique for the structural analysis of amyloid fibrils. With suitable isotope labelling patterns, SSNMR can provide constraints on the secondary structure, alignment and registration of β-strands within amyloid fibrils and identify the tertiary and quaternary contacts defining the packing of the β-sheet layers. Detection of (14)N-(13)C dipolar couplings may provide potentially useful additional structural constraints on β-sheet packing within amyloid fibrils but has not until now been exploited for this purpose. Here a frequency-selective, transfer of population in double resonance SSNMR experiment is used to detect a weak (14)N-(13)C dipolar coupling in amyloid-like fibrils of the peptide H(2)N-SNNFGAILSS-COOH, which was uniformly (13)C and (15)N labelled across the four C-terminal amino acids. The (14)N-(13)C interatomic distance between leucine and asparagine side groups is constrained between 2.4 and 3.8 Å, which allows current structural models of the β-spine arrangement within the fibrils to be refined. This procedure could be useful for the general structural analysis of other proteins in condensed phases and environments, such as biological membranes. Copyright © 2011 John Wiley & Sons, Ltd.

In the Middle of a Chain Interaction.

PubMed

Kinsella, Sinéad; Prehn, Jochen H M

2016-10-20

In this issue of Molecular Cell, Fu et al. (2016) present a detailed structural analysis of death-inducing signaling complex (DISC) assembly and regulation through flexible caspase-8 interactions with cFLIP L , cFLIP S , and the viral inhibitor MC159, thereby identifying novel apoptosis control mechanisms. Copyright © 2016 Elsevier Inc. All rights reserved.

An 8 Meter Monolithic UV/Optical Space Telescope

NASA Technical Reports Server (NTRS)

Stahl, H. Philip; Postman, Marc

2008-01-01

The planned Ares V launch vehicle with its 10 meter fairing and at least 55,600 kg capacity to Earth Sun L2 enables entirely new classes of space telescopes. A consortium from NASA, Space Telescope Science Institute, and aerospace industry are studying an 8-meter monolithic primary mirror UV/optical/NIR space telescope to enable new astrophysical research that is not feasible with existing or near-term missions, either space or ground. This paper briefly reviews the science case for such a mission and presents the results of an on-going technical feasibility study, including: optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; launch vehicle performance and trajectory; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; operations & servicing; mass budget and cost.

Crystal structure of human complement protein C8{gamma} at 1.2 {Angstrom} resolution reveals a lipocalin fold and a distinct ligand binding site.

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

Ortlund, E.; Parker, C. L.; Schreck, A. F.

2002-01-01

C8gamma is a 22-kDa subunit of human C8, which is one of five components of the cytolytic membrane attack complex of complement (MAC). C8gamma is disulfide-linked to a C8alpha subunit that is noncovalently associated with a C8beta chain. In the present study, the three-dimensional structure of recombinant C8gamma was determined by X-ray diffraction to 1.2 A resolution. The structure displays a typical lipocalin fold forming a calyx with a distinct binding pocket that is indicative of a ligand-binding function for C8gamma. When compared to other lipocalins, the overall structure is most similar to neutrophil gelatinase associated lipocalin (NGAL), a proteinmore » released from granules of activated neutrophils. Notable differences include a much deeper binding pocket in C8gamma as well as variation in the identity and position of residues lining the pocket. In C8gamma, these residues allow ligand access to a large hydrophobic cavity at the base of the calyx, whereas corresponding residues in NGAL restrict access. This suggests the natural ligands for C8gamma and NGAL are significantly different in size. Cys40 in C8gamma, which forms the disulfide bond to C8alpha, is located in a partially disordered loop (loop 1, residues 38-52) near the opening of the calyx. Access to the calyx may be regulated by movement of this loop in response to conformational changes in C8alpha during MAC formation.« less

CCR2 and CCR5 receptor-binding properties of herpesvirus-8 vMIP-II based on sequence analysis and its solution structure.

PubMed

Shao, W; Fernandez, E; Sachpatzidis, A; Wilken, J; Thompson, D A; Schweitzer, B I; Lolis, E

2001-05-01

Human herpesvirus-8 (HHV-8) is the infectious agent responsible for Kaposi's sarcoma and encodes a protein, macrophage inflammatory protein-II (vMIP-II), which shows sequence similarity to the human CC chemokines. vMIP-II has broad receptor specificity that crosses chemokine receptor subfamilies, and inhibits HIV-1 viral entry mediated by numerous chemokine receptors. In this study, the solution structure of chemically synthesized vMIP-II was determined by nuclear magnetic resonance. The protein is a monomer and possesses the chemokine fold consisting of a flexible N-terminus, three antiparallel beta strands, and a C-terminal alpha helix. Except for the N-terminal residues (residues 1-13) and the last two C-terminal residues (residues 73-74), the structure of vMIP-II is well-defined, exhibiting average rmsd of 0.35 and 0.90 A for the backbone heavy atoms and all heavy atoms of residues 14-72, respectively. Taking into account the sequence differences between the various CC chemokines and comparing their three-dimensional structures allows us to implicate residues that influence the quaternary structure and receptor binding and activation of these proteins in solution. The analysis of the sequence and three-dimensional structure of vMIP-II indicates the presence of epitopes involved in binding two receptors CCR2 and CCR5. We propose that vMIP-II was initially specific for CCR5 and acquired receptor-binding properties to CCR2 and other chemokine receptors.

Three-Dimensional Viscous Flow Analysis for Moving Bodies Past Fixed Structures

DTIC Science & Technology

1988-05-13

BELLEVUE, WA 98n)05 Research Triangle Park, UC 27709-2211 6Sý. NAME Of FUNDING I PONSORING O Ib. C’FFICE SYMBOL 9 . PROCUREMENT INSTRUMENT IPENTIFICATION...34 otheor sditico Grs IMa ý; pl S- Three- Dimvensio:.iýal Viscrous Flow Analysis for Moving Bodies Past Fixed Structures Fina.11Report, Kelton M. Peery and...Recommendations 40 List of Figures 1 Finite-Volume Mesh ......... ......................... 8 2 Finite-Volume Cell ....... ............................ 9 3

a Study of the Synchrotron Laue Method for Quantitative Crystal Structure Analysis.

NASA Astrophysics Data System (ADS)

Gomez de Anderez, Dora M.

1990-01-01

Available from UMI in association with The British Library. Quantitative crystal structure analyses have been carried out on small molecule crystals using synchrotron radiation and the Laue method. A variety of single crystal structure determinations and associated refinements are used and compared with the monochromatic analyses. The new molecular structure of 7-amino-5-bromo -4-methyl-2-oxo-1,2,3,4-tetrahidro-1, 6 -naphthyridine-8-carbonitrile (C_{10 }H_9ON_4 Br.H_2O) has been determined, first using monochromatic Mo Kalpha radiation and a four-circle diffractometer, then using synchrotron Laue diffraction photography. The structure refinements showed a R-factor of 4.97 and 14.0% for the Mo Kalpha and Laue data respectively. The molecular structure of (S)-2-chloro-2-fluoro-N-((S)-1-phenylethyl) ethanamide, (C_{10}H _{11}ClFNO), has been determined using the same crystal throughout for X-ray monochromatic analyses (Mo Kalpha and Cu K alpha) followed by synchrotron Laue data collection. The Laue and monochromatic data compare favourably. The R -factors (on F) were 6.23, 6.45 and 8.19% for the Mo K alpha, Cu Kalpha and Laue data sets respectively. The molecular structure of 3-(5-hydroxy-3-methyl-1-phenylpyrazol-4-yl)-1,3-diphenyl -prop- 2-en-1-one, (C_{25 }H_{20}N _2O_2) has been determined using the synchrotron Laue method. The results compare very well with Mo Kalpha monochromatic data. The R-factors (on F) were 4.60 and 5.29% for Mo Kalpha and Laue analysis respectively. The Laue method is assessed in locating the 20 hydrogen atoms in this structure. The structure analysis of the benzil compound ((C_6H_5 O.CO_2)) is carried out using the synchrotron Laue method firstly at room temperature and secondly at low temperature -114 ^circC. The structure shows an R-factor (on F) of 13.06% and 6.85% for each data set respectively. The synchrotron Laue method was used to collect data for ergocalciferol (Vitamin D_2). The same crystal was also used to record oscillation data with the synchrotron radiation monochromatic beam. A new molecular structure of (Dinitrato-(N,N ^'-dimethylethylene-diamine)copper(II)) has been determined using Mo Kalpha radiation on a four circle diffractometer. The refinement resulted in an R-factor (on F) of 4.06%.

Production, purification, crystallization and preliminary X-ray analysis of adeno-associated virus serotype 8

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

Lane, Michael Douglas; Nam, Hyun-Joo; Padron, Eric

2005-06-01

The production, purification, crystallization and preliminary X-ray crystallographic analysis of adeno-associated virus serotype 8 is reported. Adeno-associated viruses (AAVs) are actively being developed for clinical gene-therapy applications and the efficiencies of the vectors could be significantly improved by a detailed understanding of their viral capsid structures and the structural determinants of their tissue-transduction interactions. AAV8 is ∼80% identical to the more widely studied AAV2, but its liver-transduction efficiency is significantly greater than that of AAV2 and other serotypes. The production, purification, crystallization and preliminary X-ray crystallographic analysis of AAV8 viral capsids are reported. The crystals diffract X-rays to 3.0 Åmore » resolution using synchrotron radiation and belong to the hexagonal space group P6{sub 3}22, with unit-cell parameters a = 257.5, c = 443.5 Å. The unit cell contains two viral particles, with ten capsid viral protein monomers per crystallographic asymmetric unit.« less

Alkamides from the fruits of Piper longum and Piper nigrum displaying potent cell adhesion inhibition.

PubMed

Lee, Seung Woong; Kim, Young Kook; Kim, Koanhoi; Lee, Hyun Sun; Choi, Jung Ho; Lee, Woo Song; Jun, Chang-Duk; Park, Jee Hun; Lee, Jeong Min; Rho, Mun-Chual

2008-08-15

Eight alkamides 1-8 were isolated by bioassay-guided isolation of EtOH extracts of the fruits of Piper longum and Piper nigum (Piperaceae). Their structures were elucidated by spectroscopic analysis ((1)H, (13)C NMR, and ESI-MS) as follows: guineensine (1), retrofracamide C (2), (2E,4Z,8E)-N-[9-(3,4-methylenedioxyphenyl)-2,4,8-nonatrienoyl]piperidine (3), pipernonaline (4), piperrolein B (5), piperchabamide D (6), pellitorin (7), and dehydropipernonaline (8). Their compounds 3-5, 7, and 8 inhibited potently the direct binding between sICAM-1 and LFA-1 of THP-1 cells in a dose-dependent manner, with IC(50) values of 10.7, 8.8, 13.4, 13.5, and 6.0 microg/mL, respectively.

Globular, Sponge-like to Layer-like Morphological Transition in 1-n-Alkyl-3-methylimidazolium Octylsulfate Ionic Liquid Homologous Series.

PubMed

Kapoor, Utkarsh; Shah, Jindal K

2018-01-11

Segregation of polar and nonpolar domains in ionic liquids for which either the cation or anion is responsible for inducing nonpolar domains is well understood. On the other hand, information regarding the nanoscale heterogeneities originating due to the presence of nonpolar content on both the ions is rudimentary at this point. The present contribution is aimed at addressing this question and focuses on a molecular dynamics simulation study to probe nanoscale structural and aggregation features of the 1-n-alkyl-3-methylimidazolium [C n mim] octylsulfate [C 8 SO 4 ] ionic liquid homologous series (n = 2, 4, 6, 8, 10, and 12). The objective of this work is to determine the effect of increasing alkyl chain length in the cation on nonpolar domain formation, especially when the alkyl chain lengths from both the ions participate in defining such domains. The results indicate that all the ionic liquids form nonpolar domains, morphology of which gradually changes from globular, sponge-like to layer-like structure with increase in the cationic alkyl chain length. The length of the nonpolar domains calculated from the total structure factor for [C 10 mim][C 8 SO 4 ] is considerably higher than that reported for other imidazolium-based ionic liquid containing smaller anions. The structure factor for [C 12 mim][C 8 SO 4 ] ionic liquid contains multiple intermediate peaks separating the charge alternation peak and pre-peak, which points to nonpolar domains of varying lengths, an observation that remains to be validated. Analysis of the heterogeneous order parameters and orientational correlation functions of the alkyl chains further suggests an increase in the spatial heterogeneity and long-range order along the homologous series. The origin of rich diversity of structures obtained by introducing nonpolar content on both the ions is discussed.

Investigation of structural, ferroelectric, piezoelectric and dielectric properties of Ba0.92Ca0.08TiO3-BaTi0.96Zr0.04O3 lead-free electroceramics

NASA Astrophysics Data System (ADS)

Keswani, Bhavna C.; Patil, S. I.; Kolekar, Y. D.

2018-04-01

Lead free ferroelectric with composition 0.55Ba0.92Ca0.08TiO3-0.45BaTi0.96Zr0.04O3 (BCT8-BZT4) was synthesized by solid state reaction method and investigated their structural, ferroelectric, piezoelectric and dielectric properties. X-ray diffraction analysis shows that BCT8-BZT4 ceramic possess both tetragonal (space group P4mm) and orthorhombic (space group Amm2) crystal structure which was further confirmed from Raman spectra spectroscopy. The micronized grains were observed from scanning electron micrographs while the presence of polarization-electric field hysteresis loop confirms ferroelectric nature of BCT8-BZT4 ceramic. Higher values of maximum polarization (Pmax = 22.27 μC/cm2), remnant polarization (Pr = 11.61 μC/cm2), coercive electric field (Ec = 4.77 kV/cm) and direct piezoelectric coefficient (d33) approximately 185 pC/N were observed. The real part of dielectric constant with frequency shows the usual dielectric dispersion behaviour at RT. The observed properties show that the lead free BCT8-BZT4 ceramic is suitable for ferroelectric memory device, piezoelectric sensor, capacitor, etc. applications.

Crystal structure of (2E)-3-[4-(di-methyl-amino)-phen-yl]-1-(thio-phen-2-yl)prop-2-en-1-one.

PubMed

de Oliveira, Gabriela Porto; Bresolin, Leandro; Flores, Darlene Correia; de Farias, Renan Lira; de Oliveira, Adriano Bof

2017-04-01

The equimolar reaction between 4-(di-methyl-amino)-benzaldehyde and 2-acetyl-thio-phene in basic ethano-lic solution yields the title compound, C 15 H 15 NOS, whose mol-ecular structure matches the asymmetric unit. The mol-ecule is not planar, the dihedral angle between the aromatic and the thio-phene rings being 11.4 (2)°. In the crystal, mol-ecules are linked by C-H⋯O and weak C-H⋯S inter-actions along [100], forming R 2 2 (8) rings, and by weak C-H⋯O inter-actions along [010], forming chains with a C (6) graph-set motif. In addition, mol-ecules are connected into centrosymmetric dimers by weak C-H⋯π inter-actions, as indicated by the Hirshfeld surface analysis. The most important contributions for the crystal structure are the H⋯H (46.50%) and H⋯C (23.40%) inter-actions. The crystal packing resembles a herringbone arrangement when viewed along [100]. A mol-ecular docking calculation of the title compound with the neuraminidase enzyme was carried out. The enzyme shows ( ASN263 )N-H⋯O, ( PRO245 )C-H⋯ Cg (thio-phene ring) and ( AGR287 )C-H⋯N inter-molecular inter-actions with the title compound. The crystal structure was refined as a two-component twin with a fractional contribution to the minor domain of 0.0181 (8).

Molecular structure, vibrational spectra, NBO analysis and molecular packing prediction of 3-nitroacetanilide by ab initio HF and density functional theory.

PubMed

Li, Xiao-Hong; Li, Tong-Wei; Ju, Wei-Wei; Yong, Yong-Liang; Zhang, Xian-Zhou

2014-01-24

Quantum chemical calculations of geometries and vibrational wavenumbers of 3-nitroacetanilide (C8H8N2O3) in the ground state were carried out by using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-31+G(*) basis set. The -311++G(**) basis set is also used for B3LYP level. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. Theoretical vibrational spectra of the title compound were interpreted by means of potential energies distributions (PEDs) using MOLVIB program. The theoretical spectrograms for IR spectra of the title compound have been constructed. The shortening of C-H bond length and the elongation of N-H bond length suggest the existence of weak C-H⋯O and N-H⋯O hydrogen bonds, which is confirmed by the natural bond orbital analysis. In addition, the crystal structure obtained by molecular mechanics belongs to the P2(1) space group, with lattice parameters Z=4, a=14.9989 Å, b=4.0367 Å, c=12.9913 Å, ρ=0.998 g cm(-3). Copyright © 2013 Elsevier B.V. All rights reserved.

Water-soluble phosphine-protected Au9 clusters: Electronic structures and nuclearity conversion via phase transfer

NASA Astrophysics Data System (ADS)

Yao, Hiroshi; Tsubota, Shuhei

2017-08-01

In this article, isolation, exploration of electronic structures, and nuclearity conversion of water-soluble triphenylphosphine monosulfonate (TPPS)-protected nonagold (Au9) clusters are outlined. The Au9 clusters are obtained by the reduction of solutions containing TPPS and HAuCl4 and subsequent electrophoretic fractionation. Mass spectrometry and elemental analysis reveal the formation of [Au9(TPPS)8]5- nonagold cluster. UV-vis absorption and magnetic circular dichroism (MCD) spectra of aqueous [Au9(TPPS)8]5- are quite similar to those of [Au9(PPh3)8]3+ in organic solvent, so the solution-phase structures are likely similar for both systems. Simultaneous deconvolution analysis of absorption and MCD spectra demonstrates the presence of some weak electronic transitions that are essentially unresolved in the UV-vis absorption. Quantum chemical calculations for a model compound [Au9(pH3)8]3+ show that the possible (solution-phase) skeletal structure of the nonagold cluster has D2h core symmetry rather than C4-symmetrical centered crown conformation, which is known as the crystal form of the Au9 compound. Moreover, we find a new nuclearity conversion route from Au9 to Au8; that is, phase transfer of aqueous [Au9(TPPS)8]5- into chloroform using tetraoctylammonium bromide yields [Au8(TPPS)8]6- clusters in the absence of excess phosphine.

An Abstract Data Model for the IDEF0 Graphical Analysis Language

DTIC Science & Technology

1990-01-11

whatever level was necessary to ensure an unambiguous interpretation of the system require- ments. Marca and McGowan have written an excellent book which...December 1987. AFIT/GE/ENG/87D-28. [7] MARCA , D. A., AND McGOWAN, C. L. SADT Structured Analysis and Design Technique. McGraw- Hill Book Company, 1988. [8

Analysis of Fusarium mycotoxins by gas chromatography--Fourier transform infrared spectroscopy.

PubMed

Young, J C; Games, D E

1994-03-11

The Fourier transform infrared (FTIR) spectra of selected Fusarium mycotoxins of various structure types were determined. Absorptions were observed for the following functionalities: hydroxyl at 3625-65 cm-1 and 3482 cm-1, the latter being associated with a 7 alpha-hydroxyl adjacent to an 8-carbonyl in keto trichothecenes; carbonyl at 1760-6 cm-1 for 5-membered rings and at 1695-8 cm-1 for those conjugated to a single C = C in a six-membered ring; acetate carbonyl at 1765 cm-1 and acetate C-O at 1220-9 cm-1; and C = C at 1680 cm-1. Gas chromatography combined with FTIR and mass spectrometry was applied to the identification of some mycotoxins in a F. roseum liquid culture extract.

Structural changes during a liquid-liquid transition in the deeply undercooled Z r58.5C u15.6N i12.8A l10.3N b2.8 bulk metallic glass forming melt

NASA Astrophysics Data System (ADS)

Stolpe, Moritz; Jonas, Isabell; Wei, Shuai; Evenson, Zach; Hembree, William; Yang, Fan; Meyer, Andreas; Busch, Ralf

2016-01-01

Using high energy synchrotron x-ray radiation combined with electrostatic levitation, in situ structural analysis of a bulk metallic glass forming liquid is performed from above the liquidus temperature down to the glass transition. The data indicate a liquid-liquid transition (LLT) in the deeply undercooled state at T /Tg˜1.2 which manifests as a maximum in the heat capacity and an abrupt shift in the first peak position of the total structure factor in the absence of a pronounced density change. Analysis of the corresponding real-space data shows that the LLT involves changes in short- and medium-range order. The structural changes on the length scale of medium-range order imply a fragile-strong transition in agreement with experimental viscosity data.

A new isocoumarin from Cajanus cajan (Fabaceae).

PubMed

Rodrigues, Virginia F; Oliveira, Rodrigo R; Vega, Maria Raquel G

2014-04-01

A new isocoumarin, 3-phenyl-8-hydroxy-6-methoxy-5-gamma,gamma-dimethylallyl-isocoumarin, named cajavilmina (1) and eight known compounds: a-amirenone (2), beta-amirenone (3), lupenone (4), 5-hydroxy-7-methoxydihydroflavone (5), longistilin C (6), 3-hydroxy-5-methoxystilbene (7), beta-sitosterol (8) and stigmasterol (9) were identified in a dichloromethane fraction from Cajanus cajan leaves. Structures were elucidated by analysis of spectral data, mainly those afforded by 1H, NOEDIFF and 13C NMR (1D and 2D NMR HMQC, HMBC and COSY) and mass spectra.

Core-Level Photoemission Investigations of the CADMIUM-TELLURIDE(100) and INDIUM-ANTIMONY(100) Surface and Interfacial Structures.

NASA Astrophysics Data System (ADS)

John, Peter James

1988-12-01

Photoemission techniques, utilizing a synchrotron light source, were used to analyze the clean (100) surfaces of the zinc-blende semiconductor materials CdTe and InSb. Several interfacial systems involving the surfaces of these materials were also studied, including the CdTe(100)-Ag interface, the CdTe(100)-Sb system, and the InSb(100)-Sn interface. High -energy electron diffraction was also employed to acquire information about of surface structure. A one-domain (2x1) structure was observed for the CdTe(100) surface. Analysis of photoemission spectra of the Cd 4d core level for this surface structure revealed two components resulting from Cd surface atoms. The total intensity of these components accounts for a full monolayer of Cd atoms on the surface. A structural model is discussed commensurate with these results. Photoemission spectra of the Cd and Te 4d core levels indicate that Ag or Sb deposited on the CdTe(100)-(2x1) surface at room temperature do not bound strongly to the surface Cd atoms. The room temperature growth characteristics for these two elements on the CdTe(100)-(2x1) are discussed. The growth at elevated substrate temperatures was also studied for Sb deposition. The InSb(100) surface differed from the CdTe(100) surface. Using molecular beam epitaxy, several structures could be generated for the InSb(100) surface, including a c(8x2), a c(4x4), an asymmetric (1x3), a symmetric (1x3), and a (1x1). Analysis of photoemission intensities and line shapes indicates that the c(4x4) surface is terminated with 1{3 over 4} monolayers of Sb atoms. The c(8x2) surface is found to be terminated with {3over 4} monolayer of In atoms. Structural models for both of these surfaces are proposed based upon the photoemission results and upon models of the similar GaAs(100) structures. The room temperature growth characteristics of grey Sn on the InSb(100)-c(4x4) and InSb(100)-c(8x2) surfaces were studied with photoemission. The discontinuity in the valence band maximum for this semiconductor heterojunction system is measured to be 0.40 eV, independent of the starting surface structure and stoichiometry. This result is reconciled with theoretical predictions for heterostructure behavior.

[Chemical Constituents from Processed Products of Aconitum Vilmoriniani Radix].

PubMed

Guo, Zhi-jun; Yang, Zhu-ya; Tan, Wen-hong; Zhou, Zhi-hong; Ma, Xiao-xia

2015-05-01

To investigate the chemical constituents of the processed products of Aconitum Vilmorinian Radix. The constituents were isolated by repeated column chromatography over silica gel, alumina and RP-C18 as well as recrystallization. The structures were elucidated on the basis of spectral analysis and physicochemical properties. Ten compounds were obtained from the methanol extract, and they were identified as yunaconitine (1), 8-deacetyl-yunaconitine (2), geniculatine C (3), vilmorrianine B (4), vilmorrianine C(5), vilmorrianine D (6), talatisamine (7), β-sitosterol (8), β-daucosterol (9) and β-sitosterol acetate (10). All compounds are obtained from the processed products of Aconitum Vilmoriniani Radix for the first time.

Structure elucidation of 3-[1-(6-methoxy-2-naphtyl)ethyl]-6-(2,4-dichlorophenyl)-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine, C 23H 18Cl 2N 4OS from synchrotron X-ray powder diffraction

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

Gündoğdu, Gülsüm; Aytaç, Sevim Peri; Müller, Melanie

The 3-[1-(6-methoxy-2-naphtyl)ethyl]-6-(2,4-dichlorophenyl)-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine, C 23H 18Cl 2N 4OS compound was synthesized, as a member of the family of novel potential anticancer agents. The structure of the title compound was characterized by IR, 1H-NMR, mass spectroscopy, and elemental analysis, previously. In this study, the crystal structure of this compound has been determined from synchrotron X-ray powder diffraction data. The crystal structure was solved by simulated annealing and the final structure was achieved by Rietveld refinement method using soft restrains on all interatomic bond lengths and angles. This compound crystallizes in space groupP21,Z= 2, with the unit-cell parametersa= 15.55645(11) Å,b= 8.61693(6) Å,c= 8.56702(6)more » Å,β= 104.3270(4)°, andV= 1112.68(1) Å 3. In the crystal structure, strong C-H∙∙∙πand weak intermolecular hydrogen-bonding interactions link the molecules into a three-dimensional network. The molecules are in a head-to-head arrangement in the unit cell.« less

Elaboration, structural, spectroscopy, DSC investigations and Hirshfeld surface analysis of a one-dimensional self-assembled organic-inorganic hybrid compound

NASA Astrophysics Data System (ADS)

Mesbeh, Radhia; Hamdi, Besma; Zouari, Ridha

2017-01-01

The new organic-inorganic hybrid of the formula [H2mela]Cu2Cl6, where mela = 1,3,5-triazine-2,4,6-triamine, has been synthesized by the reaction of 1,3,5-triazine-2,4,6-triamine and copper(II) chloride dihydrate in the presence of hydrochloric acid. This compound has been determined by X-ray diffraction analysis and characterized by FT-IR, Raman, NMR characterization, differential scanning calorimetric (DSC) analysis, dielectric measurements and Hirshfeld surface. 1,3,5-triazinidium-2,4,6-triamine hexachlorodicuprate(II) crystallizes in the monoclinic system with space group P21/c. The final refinement of the structure of the program led to the reliability factors unweighted R1 = 3.53% and weighted WR2 = 8.87%. The observed internal C3sbnd N31sbnd C1 and C3sbnd N23sbnd C2 angle (121.5 and 121.4°) at protanated N-atom are significantly greater the other ring angle C1sbnd N12sbnd C2 (117.1°). The titled compound crystallizes as an organic-inorganic one-dimensional (1D) structure. The crystal structure was stabilized by two types of hydrogen bonding Nsbnd H⋯Cl and Nsbnd H⋯N. The infrared spectra was recorded in the 4000-400 cm-1 frequency region and the Raman spectra was recorded in the external region of the anionic sublattice vibration 4000-50 cm-1 at room temperature. Solid-state 13C and 63Cu MAS-NMR spectroscopies are in agreement with the X-ray structure. The differential scanning calorimetric (DSC) show the presence of a structural phase transition of the title compound at 338 K. Hirshfeld surface analyses for visually analyzing intermolecular interactions in crystal structures employing molecular surface contours and 2D fingerprint plots have been used to examine molecular shapes.

Copper tolerance in Frankia sp. strain EuI1c involves surface binding and copper transport.

PubMed

Rehan, Medhat; Furnholm, Teal; Finethy, Ryan H; Chu, Feixia; El-Fadly, Gomaah; Tisa, Louis S

2014-09-01

Several Frankia strains have been shown to be copper-tolerant. The mechanism of their copper tolerance was investigated for Frankia sp. strain EuI1c. Copper binding was shown by binding studies. Unusual globular structures were observed on the surface of the bacterium. These globular structures were composed of aggregates containing many relatively smaller "leaf-like" structures. Scanning electron microscopy with energy-dispersive X-ray (SEM-EDAX) analysis of these structures indicated elevated copper and phosphate levels compared to the control cells. Fourier transform infrared spectroscopy (FTIR) analysis indicated an increase in extracellular phosphate on the cell surface of copper-stressed cells. Bioinformatics' analysis of the Frankia sp. strain EuI1c genome revealed five potential cop genes: copA, copZ, copC, copCD, and copD. Experiments with Frankia sp. strain EuI1c using qRT-PCR indicated an increase in messenger RNA (mRNA) levels of the five cop genes upon Cu(2+) stress. After 5 days of Cu(2+) stress, the copA, copZ, copC, copCD, and copD mRNA levels increased 25-, 8-, 18-, 18-, and 25-fold, respectively. The protein profile of Cu(2+)-stressed Frankia sp. strain EuI1c cells revealed the upregulation of a 36.7 kDa protein that was identified as FraEuI1c_1092 (sulfate-binding periplasmic transport protein). Homologues of this gene were only present in the genomes of the Cu(2+)-resistant Frankia strains (EuI1c, DC12, and CN3). These data indicate that copper tolerance by Frankia sp. strain EuI1c involved the binding of copper to the cell surface and transport proteins.

The Disgust Scale: Item Analysis, Factor Structure, and Suggestions for Refinement

ERIC Educational Resources Information Center

Olatunji, Bunmi O.; Williams, Nathan L.; Tolin, David F.; Abramowitz, Jonathan S.; Sawchuk, Craig N.; Lohr, Jeffrey M.; Elwood, Lisa S.

2007-01-01

In the 4 studies presented (N = 1,939), a converging set of analyses was conducted to evaluate the item adequacy, factor structure, reliability, and validity of the Disgust Scale (DS; J. Haidt, C. McCauley, & P. Rozin, 1994). The results suggest that 7 items (i.e., Items 2, 7, 8, 21, 23, 24, and 25) should be considered for removal from the DS.…

Structure analysis of BaCe{sub 0.8}Y{sub 0.2}O{sub 3−δ} in dry and wet atmospheres by high-temperature X-ray diffraction measurement

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

Han, Donglin, E-mail: han.donglin.8n@kyoto-u.ac.jp; Majima, Masatoshi; Uda, Tetsuya, E-mail: materials_process@aqua.mtl.kyoto-u.ac.jp

2013-09-15

High temperature X-ray diffraction measurements were performed under dry and wet atmospheres to investigate phase behavior of BaCe{sub 0.8}Y{sub 0.2}O{sub 3−δ} (BCY20). In the temperature range of 30–400 °C, BCY20 was identified to be rhombohedral and monoclinic structures in dry and wet atmospheres, respectively. Larger lattice volumes were obtained in a wet atmosphere due to a chemical expansion induced by water incorporation. A gradual change in diffraction peak shape due to a phase transformation from rhombohedral to monoclinic was observed at 300 °C when moisture was introduced into the atmosphere. These results indicated clearly the dependence of phase behavior ofmore » BCY20 on partial pressure of water vapor in atmosphere. - Graphical abstract: A BaCe{sub 0.8}Y{sub 0.2}O{sub 3−δ} rhombohedral phase transited to a monoclinic phase at 300 °C when moisture was introduced into the atmosphere. Display Omitted - Highlights: • Different structures for hydrated and dehydrated BaCe{sub 0.8}Y{sub 0.2}O{sub 3−δ} (BCY20). • Slow phase transition from rhombohedral to monoclinic at 300 °C in wet atmosphere. • Chemical expansion of BCY20 in wet atmosphere. • Importance of considering moisture when discussing phase behavior of BCY20.« less

Structure determination of two structural analogs, named 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-fluorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C23H16F2N4S) and 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-chlorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C23H16ClFN4S) by synchrotron X-ray powder diffraction

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

Gündoğdu, Gülsüm; Aytaç, Sevim Peri; Müller, Melanie

Two novel compounds, 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-fluorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C 23H 16F 2N 4S) (1) and 3-[1-(2-fluoro-4-biphenyl)ethyl]-6-(4-chlorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C 23H 16ClFN 4S) (2), have been designed and synthesized as cytotoxic agents. The compounds were characterized by infrared, proton nuclear magnetic resonance, mass spectral data, elemental analysis and X-ray powder diffraction. The present study comprises spectral data and crystal structures of these novel compounds determined from synchrotron X-ray powder diffraction data. The structure solutions were obtained by simulated annealing. The final structures were achieved by Rietveld refinement using soft restraints for all bond lengths, bond angles, and planar groups. Both compounds crystallize in space groupmore » $$P\\bar 1$$,Z= 2, with the unit-cell parametersa= 6.37433(9),b= 11.3641(2),c= 14.09115(19) Å,α= 80.1740(8)°,β= 85.1164(8)°,γ= 80.9831(10)°,V= 991.55(3) Å 3of compound (1) anda= 6.53736(6),b= 11.55725(15),c= 14.01373(13) Å,α= 80.3323(7)°,β= 84.8939(6)°,γ= 79.3954(8)°,V= 1024.08(2) Å 3of compound (2). Structural analyses reveal that the title compounds are isostructural.« less

Effects of ionizing radiation and temperature on uranyl silicates: soddyite (UO2)2(SiO4)(H2O)2 and Uranophane Ca(UO2)2(SiO3OH)2·5H2O.

PubMed

Sureda, R; Casas, I; Giménez, J; de Pablo, J; Quiñones, J; Zhang, J; Ewing, R C

2011-03-15

The stability of soddyite under electron irradiation has been studied over the temperature range of 25-300 °C. At room temperature, soddyite undergoes a crystalline-to-amorphous transformation (amorphization) at a total dose of 6.38 × 10(8) Gy. The electron beam irradiation results suggest that the soddyite structure is susceptible to radiation-induced nanocrystallization of UO(2). The temperature dependence of amorphization dose increases linearly up to 300 °C. A thermogravimetric and calorimetric analysis (TGA-DSC) combined with X-ray diffraction (XRD) indicates that soddyite retains its water groups up to 400 °C, followed by the collapse of the structure. Based on thermal analysis of uranophane, the removal of some water groups at relatively low temperatures provokes the collapse of the uranophane structure. This structural change appears to be the reason for the increase of amorphization dose at 140 °C. According to the results obtained, radiation field of a nuclear waste repository, rather than temperature effects, may cause changes in the crystallinity of soddyite and affect its stability during long-term storage.

Impact of self-assembled surfactant structures on rheology of concentrated nanoparticle dispersions.

PubMed

Zaman, A A; Singh, P; Moudgil, B M

2002-07-15

Rheological behavior of surfactant-stabilized colloidal dispersions of silica particles under extreme conditions (low pH, high ionic strength) has been investigated in relation to interparticle forces and stability of the dispersion. The surfactant used as the dispersing agent was C(12)TAB, a cationic surfactant. Stability analysis through turbidity measurements indicated that there is a sharp increase in the stability of the dispersion when the surfactant concentration is in the range of 8 to 10 mM in the system. The state of the dispersion changes from an unstable regime to a stable regime above a critical concentration of C(12)TAB in the system. In the case of interaction forces measured between the silica substrate and AFM tip, no repulsive force was observed up to a surfactant concentration of 8 mM and a transition from no repulsive forces to steric repulsive forces occurred between 8 and 10 mM. Rheological measurements as a function of C(12)TAB concentration indicated a significant decrease in the viscosity and linear viscoelastic functions of the dispersion over the same range of surfactant concentration (8 to 10 mM C(12)TAB), showing a strong correlation between the viscosity behavior, interparticle forces, and structure development in the dispersion.

Cervarix, the GSK HPV-16/HPV-18 AS04-adjuvanted cervical cancer vaccine, demonstrates stability upon long-term storage and under simulated cold chain break conditions.

PubMed

Le Tallec, David; Doucet, Diane; Elouahabi, Abdelatif; Harvengt, Pol; Deschuyteneer, Michel; Deschamps, Marguerite

2009-07-01

Cervarix is a recombinant human papillomavirus (HPV)-16 and -18 L1 virus-like-particle (VLP) AS04-adjuvanted vaccine designed to protect against cervical intraepithelial neoplasia and cervical cancer caused by the HPV types 16 and 18. Assessment of the stability of the vaccine during long-term storage and after transient exposure to temperatures out of normal storage range is an integrated part of vaccine quality evaluation. This assessment was done with vaccine samples stored at 2-8 degrees C for up to 36 months, with or without simulated cold chain break (either one week at 37 degrees C, or two or four weeks at 25 degrees C). Among the stability-indicating parameters, antigenicity and immunogenicity were evaluated along with L1 antigen integrity and adsorption to aluminum. Differential scanning calorimetry (DSC) was used to investigate the structural stability of the VLPs before and after vaccine formulation and over time. Cervarix was stable at 2-8 degrees C for at least three years, and the occurrence of cold chain break had no impact, as shown by unchanged product characteristics during the full storage period. DSC analysis demonstrated that the structure of the HPV-16 and -18 L1 proteins and their corresponding VLPs was not affected throughout the manufacturing process. Moreover, the structure of aluminum-adsorbed HPV-16 and -18 L1 VLPs was robust over a 14-month test period. In conclusion, Cervarix was very stable upon long-term storage at 2-8 degrees C with or without transient exposure to higher temperatures (up to 37 degrees C). The observed robust structure of the L1 VLPs contributes to the excellent stability of Cervarix.

Conformational study and structure of N-(2,5-methylphenyl)salicylaldimine

NASA Astrophysics Data System (ADS)

Elmali, A.; Elerman, Y.; Zeyrek, C. T.

1998-02-01

N-(2,5-methylphenyl)salicylaldimine (C 15H 15NO) has been investigated by X-ray analysis and AM1 semi-empirical quantum mechanical method. The crystal is in the orthorhombic space group P2 12 12 1 with a = 6.839(1), b = 7.720(4), c = 23.183(3) Å, V = 1224.1(2) Å3, Z = 4, Dc = 1.222 g cm -3 and μ(Mo K α) = 0.076 mm -1. The title structure was solved by direct methods and refined to R = 0.0364 for 1489 reflections [ I > 2 σ( I)] by full-matrix anisotropic least-squares methods. The title compound is photochromic and the molecule is not planar. There is a strong intramolecular hydrogen bond of distance 2.604(2) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformations from AM1 were calculated as a function of three torsion angles, θ1 (C8N1C7C6), θ2 (C9C8N1C7) and θ3 (N1C7C6C5), varied every 10°. The optimized geometry of the crystal structure corresponding to non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by non-bonded hydrogen-hydrogen repulsions.

Crystal Structure Analysis of Electromagnetic Wave Absorber Material BaFe12-xTix/2Znx/2O19Based

NASA Astrophysics Data System (ADS)

Delina, M.; Nenni, N.; Adi, W. A.

2018-04-01

The optimization of BaFe12-xTix/2Znx/2O19 (x=2.2; 2.4; 2.6; 2.8)single phase composition have been performed. The materials were synthesized by solid state reaction method through mechanical milling technique.The materials were made from the mixture of oxide materials, which are BaCO3, Fe2O3, TiO2 and ZnO. The mixture was milled for five hours using a High Energy Milling (HEM), was dried at 100°C in the Oven and then was sintered at 1000°C for five hours in the Furnace. The phase identification of BaFe12-xTix/2Znx/2O19 (x=2.2; 2.4; 2.6; 2.8) were carried out by using a Match Program while the crystal structure analysis were investigated by using a General Structure Analysis System (GSAS) program. The refinement results of x-ray diffraction pattern showed that the sample of x ≤ 2.4 have a BaFe12O19 single phase while the sample of x> 2.4 have two phases, which are BaFe12O19 and ZnFe2O4 phases. The surface morphology of sample and the element of sample were identified through an analysis of Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) data.

Inhibition of telomerase by linear-chain fatty acids: a structural analysis.

PubMed Central

Oda, Masako; Ueno, Takamasa; Kasai, Nobuyuki; Takahashi, Hirotada; Yoshida, Hiromi; Sugawara, Fumio; Sakaguchi, Kengo; Hayashi, Hideya; Mizushina, Yoshiyuki

2002-01-01

In the present study, we have found that mono-unsaturated linear-chain fatty acids in the cis configuration with C(18) hydrocarbon chains (i.e. oleic acid) strongly inhibited the activity of human telomerase in a cell-free enzymic assay, with an IC(50) value of 8.6 microM. Interestingly, fatty acids with hydrocarbon chain lengths below 16 or above 20 carbons substantially decreased the potency of inhibition of telomerase. Moreover, the cis-mono-unsaturated C(18) linear-chain fatty acid oleic acid was the strongest inhibitor of all the fatty acids tested. A kinetic study revealed that oleic acid competitively inhibited the activity of telomerase ( K (i)=3.06 microM) with respect to the telomerase substrate primer. The energy-minimized three-dimensional structure of the linear-chain fatty acid was calculated and modelled. A molecule width of 11.53-14.26 A (where 1 A=0.1 nm) in the C(16) to C(20) fatty acid structure was suggested to be important for telomerase inhibition. The three-dimensional structure of the telomerase active site (i.e. the substrate primer-binding site) appears to have a pocket that could bind oleic acid, with the pocket being 8.50 A long and 12.80 A wide. PMID:12121150

Crystallization and preliminary X-ray crystallographic analysis of agkicetin-C from Deinagkistrodon acutus venom

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

Xu, Gufeng; Departments of Molecular and Cell Biology, School of Life Sciences, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026; Huang, Qingqiu

2005-01-01

The crystallization and preliminary crystallographic analysis of agkicetin-C, a well known platelet glycoprotein Ib (GPIb) antagonist from the venom of Deinagkistrodon acutus found in Anhui Province, China is reported. The crystallization and preliminary crystallographic analysis of agkicetin-C, a well known platelet glycoprotein Ib (GPIb) antagonist from the venom of Deinagkistrodon acutus found in Anhui Province, China is reported. Crystals of agkicetin-C suitable for structure determination were obtained from 1.8 M ammonium sulfate, 40 mM MES pH 6.5 with 2%(v/v) PEG 400. Interestingly, low buffer concentrations of MES seem to be necessary for crystal growth. The crystals of agkicetin-C belong tomore » space group C2, with unit-cell parameters a = 177.5, b = 97.7, c = 106.8 Å, β = 118.5°, and diffract to 2.4 Å resolution. Solution of the phase problem by the molecular-replacement method shows that there are four agkicetin-C molecules in the asymmetric unit, with a V{sub M} value of 3.4 Å{sup 3} Da{sup −1}, which corresponds to a high solvent content of approximately 64%. Self-rotation function calculations show a single well defined non-crystallographic twofold axis with features that may represent additional elements of non-crystallographic symmetry.« less

Ambipolar carrier transport properties and molecular packing structure of octahexyl-substituted copper phthalocyanine

NASA Astrophysics Data System (ADS)

Watanabe, Ken; Watanabe, Koichi; Tohnai, Norimitsu; Itani, Hiromichi; Shimizu, Yo; Fujii, Akihiko; Ozaki, Masanori

2018-04-01

The charge carrier mobility of a solution-processable low-molecular-weight organic semiconductor material, i.e., 1,4,8,11,15,18,22,25-octahexylphthalocyanine copper complex (C6PcCu), was investigated by the time-of-flight technique. The anomalous ambipolar carrier mobility was discussed from the viewpoint of the molecular packing structure, which was clarified by single-crystal X-ray structure analysis. In the comparison between the molecular packing structures of C6PcCu and its metal-free-type homologue, it was found that the difference in carrier mobility originates from the rotation of the molecule, which is caused by the steric hindrance due to the introduction of a center metal and the interpenetration of the nonperipheral alkyl chains.

Potential of extracts from Saponaria officinalis and Calendula officinalis to modulate in vitro rumen fermentation with respect to their content in saponins.

PubMed

Budan, Alexandre; Bellenot, Denis; Freuze, Ingrid; Gillmann, Louisa; Chicoteau, Pierre; Richomme, Pascal; Guilet, David

2014-01-01

Saponins have the potential to favorably modulate rumen fermentation, but there is generally a lack of the chemical structures associated with the described effects. The activity of extracts from Calendula officinalis and Saponaria officinalis in the rumen was evaluated in vitro. The S. officinalis root extract, reduced CH₄ production by 8.5% and increased total VFA concentration by 25.2%. C. officinalis and S. officinalis root extracts and the S. officinalis aerial part extract decreased the acetate to propionate ratio from 8.6 to 17.4%, according to the extract. An HPLC-ELSD analysis indicated that the saponin content ranged from 43.6 to 57.6 mg/g of dry matter (DM) in the C. officinalis extracts and from 224.0 to 693.8 mg/g of DM in the S. officinalis extracts, expressed as the hederacoside C equivalent. Identification of the saponin compounds present in the extracts by HPLC-MS(n) suggested that the saponin profile modulated the biological activities, showing the importance of determining the structure of saponins when evaluating extracts.

The crystal structures of potassium and cesium trivanadates

USGS Publications Warehouse

Evans, H.T.; Block, S.

1966-01-01

Potassium and cesium trivanadates are monoclinic and isomorphous, space group P21/m, with the following dimensions (Z = 2): KV3O8, a = 7.640 A, b = 8.380 A, c = 4.979 A, ??= 96?? 57???; CsV3O8, a = 8.176 A, b = 8.519 A, c = 4.988 A, ?? = 95?? 32???. The crystal structure of KV3O8 has been determined from hk0, 0kl, and h0l Weissenberg data with an R factor of 0.15. The structure of CsV3O8 has been refined with 1273 hkl Weissenberg data to an R factor of 0.089. The structures consist of corrugated sheets based on a linkage of distorted VO6, octahedra. Two of the vanadium atoms lie in double, square-pyramid groups V2O8, which are linked through opposite basal corners into chains along the b axis. The chains are joined laterally along the c axis into sheets by the third vanadium atom in VO groups, also forming part of a square-pyramid coordination. Various aspects of these structures are compared with other known oxovanadate structures.

A Sterically Biased Unsymmetrical Azobenzene Derivative: Synthesis, Molecular Structure, and 15N NMR Spectroscopic Analysis of (E)-1-(2,6-Diisopropylphenyl)-2-phenyldiazine

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

Baumann, David O.; Erickson, Karla A.; Scott, Brian L.

We synthesized and characterized the title compound, (E)-1-(2,6-diisopropylphenyl)-2-phenyldiazine (I) using a combination of 1H, 13C, and 15N NMR spectroscopy, infrared and UV/Vis spectroscopy, X-ray crystallography, and GC mass spectrometry. The solid-state structure is also reported. The unsymmetric azobenzene crystallizes in the space group P2 1/c with unit cell parameters a = 8.001(7) Å, b = 17.827(16) Å, c = 11.129(10) Å, β = 101.960(10)°, V = 1553(2) Å 3, Z = 4, D calc = 1.139 g/cm 3.

A Sterically Biased Unsymmetrical Azobenzene Derivative: Synthesis, Molecular Structure, and 15N NMR Spectroscopic Analysis of (E)-1-(2,6-Diisopropylphenyl)-2-phenyldiazine

DOE PAGES

Baumann, David O.; Erickson, Karla A.; Scott, Brian L.; ...

2017-10-24

We synthesized and characterized the title compound, (E)-1-(2,6-diisopropylphenyl)-2-phenyldiazine (I) using a combination of 1H, 13C, and 15N NMR spectroscopy, infrared and UV/Vis spectroscopy, X-ray crystallography, and GC mass spectrometry. The solid-state structure is also reported. The unsymmetric azobenzene crystallizes in the space group P2 1/c with unit cell parameters a = 8.001(7) Å, b = 17.827(16) Å, c = 11.129(10) Å, β = 101.960(10)°, V = 1553(2) Å 3, Z = 4, D calc = 1.139 g/cm 3.

Electronic Structures and Nanofilm Growth of 2,7-Dioctyl[1]Benzothieno[3,2-b]Benzothiophene on Black Phosphorus.

PubMed

Wei, Xuhui; Wang, Shitan; Wang, Can; Zhu, Menglong; Zhao, Yuan; Xie, Haipeng; Niu, Dongmei; Gao, Yongli

2018-06-01

The interfacial electronic structure and morphology of nanofilm of 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on black phosphorus (BP) was investigated with photoemission spectroscopy (PES) and atomic force microscopy (AFM). The heterojunction of C8-BTBT/BP is a straddling one with a hole injection barrier of 1.41 eV and electron injection barrier of 2.43 eV from BP to C8-BTBT. There is a 0.18 eV interface dipole pointing from BP to C8-BTBT, which means a relative weak interaction of substrate BP and the C8-BTBT molecules. Volmer-Weber growth mode of C8-BTBT nanofilm on BP was confirmed and the C8-BTBT molecules adopt standing up configuration.

Crystal Structure of the C-terminal Domain of Splicing Factor Prp8 Carrying Retinitis Pigmentosa Mutants

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

Zhang,L.; Shen, J.; Guarnieri, M.

2007-01-01

Prp8 is a critical pre-mRNA splicing factor. Prp8 is proposed to help form and stabilize the spliceosome catalytic core and to be an important regulator of spliceosome activation. Mutations in human Prp8 (hPrp8) cause a severe form of the genetic disorder retinitis pigmentosa, RP13. Understanding the molecular mechanism of Prp8's function in pre-mRNA splicing and RP13 has been hindered by its large size (over 2000 amino acids) and remarkably low-sequence similarity with other proteins. Here we present the crystal structure of the C-terminal domain (the last 273 residues) of Caenorhabditis elegans Prp8 (cPrp8). The core of the C-terminal domain ismore » an / structure that forms the MPN (Mpr1, Pad1 N-terminal) fold but without Zn{sup 2+} coordination. We propose that the C-terminal domain is a protein interaction domain instead of a Zn{sup 2+}-dependent metalloenzyme as proposed for some MPN proteins. Mapping of RP13 mutants on the Prp8 structure suggests that these residues constitute a binding surface between Prp8 and other partner(s), and the disruption of this interaction provides a plausible molecular mechanism for RP13.« less

Reinvestigation of structure of porritoxin, a phytotoxin of Alternaria porri.

PubMed

Horiuchi, Masayuki; Maoka, Takashi; Iwase, Noriyasu; Ohnishi, Keiichiro

2002-08-01

The structure of porritoxin, a phytotoxin of Alternaria porri, was reinvestigated by detailed 2D NMR analysis including (1)H-(13)C and (1)H-(15)N HMBC experiments. The structure of porritoxin was determined to be 2-(2'-hydroxyethyl)-4-methoxy-5-methyl-6-(3' '-methyl-2' '-butenyloxy)-2,3-dihydro-1H-isoindol-1-one (1). Thus our previous proposed structure, 8-(3',3'-dimethylallyloxy)-10-methoxy-9-methyl-1H-3,4-dihydro-2,5-benzoxazocin-6(5H)-one (2), is incorrect.

Intermolecular interactions in the solid state structures of neutral and N-protonated 5-alkoxymethyl-8-hydroxyquinolines

NASA Astrophysics Data System (ADS)

Schulze, Mathias M.; Böhme, Uwe; Schwarzer, Anke; Weber, Edwin

2017-04-01

A series of five different alkoxymethyl substituted derivatives of 8-hydroxyquinoline was synthesised both in protonated (1a-1e) and neutral (2a-2e) form. The alkoxymethyl groups are MeO (1a, 2a), EtO (1b, 2b), n-PrO (1c, 2c), iso-PrO (1d, 2d), n-BuO (1e, 2e). The compounds were characterised by single crystal X-ray diffraction and spectroscopic methods. Hirshfeld surface analysis was performed to analyse the crystal packing quantitatively. Topological analysis of the electron density distribution delivers information about the strength of the hydrogen bonds. The overall results reveal a main difference between the charged (1a-1d) and uncharged (2a-2e) compounds in the orientation of the hydroxyl group resulting in a different cyclic dimer formation. In both cases the structures are dominated by hydrogen bonding (1a-1d: Osbnd H⋯Cl, Nsbnd H⋯Cl and 2a-2e: Osbnd H⋯N). Furthermore, all crystal structures show π involved interactions though taking only a minor part in the packing of the molecules.

Structural characterization and Hirshfeld surface analysis of racemic baclofen

NASA Astrophysics Data System (ADS)

Maniukiewicz, Waldemar; Oracz, Monika; Sieroń, Lesław

2016-11-01

The crystal structure of baclofen, (R,S) [4-amino-3-(4-chlorophenyl)butanoic acid], (C10H12ClNO2, Mr = 213.66) has been determined by single crystal X-ray diffraction analysis. The title compound crystallizes in the orthorhombic space group Pbca (No. 61) with a = 9.2704(5), b = 7.0397(4), c = 30.4015(15) Å, V = 1984.0(2) Å3 and Z = 8. The molecules exist as zwitterions, adopting a gauche conformation with respect to the Cαsbnd Cβ bond, and held in a cross-linked chain arrangement by strong Nsbnd H⋯O hydrogen bonds and Csbnd Cl⋯π interactions. The electrostatic molecular potential as well as the intermolecular interactions of the title compound were analyzed by the Hirshfeld surfaces. The FT-IR spectrum is also reported. The DTA, TG and DTG results indicate that baclofen is stable up to 205 °C.

Solution structure of an artificial Fe8S8 ferredoxin: the D13C variant of Bacillus schlegelii Fe7S8 ferredoxin.

PubMed

Aono, S; Bentrop, D; Bertini, I; Cosenza, G; Luchinat, C

1998-12-01

The solution structure of the D13C variant of the thermostable Fe7S8 ferredoxin from Bacillus schlegelii has been determined by 1H-NMR spectroscopy in its oxidized form. In a variable-temperature NMR study the D13C variant was as thermostable (up to 90 degrees C) as the wild-type protein (WT). Seventy-five out of 77 amino acid residues and 81% of all theoretically expected proton resonances in the D13C Fe8S8 protein have been assigned. Its structure was determined through torsion angle dynamics calculations with the program DYANA, using 935 meaningful NOEs (from a total of 1251), hydrogen bond constraints, and NMR-derived dihedral angle constraints for the cluster-ligating cysteines. Afterwards, restrained energy minimization and restrained molecular dynamics were applied to each conformer of the family. The final family of 20 structures has RMSD values from the mean structure of 0.055 nm for the backbone atoms and of 0.099 nm for all heavy atoms. The overall folding of the WT is maintained in the mutant, except for the immediate vicinity of the new cysteine, which becomes much more similar to native Fe8S8 proteins. The two residues at positions 11 and 12, which constitute an insertion with respect to all known Fe8S8 proteins, assume a conformation that does not prevent the preceding and following residues from folding like in native Fe8S8 proteins. Clear evidence for the existence of two conformations involving almost half of the amino acid residues was found. The two conformations are structurally indistinguishable. Temperature-dependent NMR experiments show that one of them is thermodynamically more stable than the other.

The correlations of the electronic structure and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on SiO2.

PubMed

Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Zhao, Yuan; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

2017-01-04

Combining ultraviolet photoemission spectroscopy (UPS), X-ray photoemission spectroscopy (XPS), atomic force microscopy (AFM) and small angle X-ray diffraction (SAXD) measurements, we perform a systematic investigation on the correlations of the electronic structure, film growth and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on silicon oxide (SiO 2 ). AFM analysis reveals a phase transition of disorderedly oriented molecules in clusters in thinner films to highly ordered standing-up molecules in islands in thicker films. SAXD peaks consistently support the standing-up configuration in islands. The increasing ordering of the molecular orientation with film thickness contributes to the changing of the shape and lowering of the leading edge of the highest occupied molecular orbital (HOMO). The end methyl of the highly ordered standing molecules forms an outward pointing dipole layer which makes the work function (WF) decrease with increasing thickness. The downward shift of the HOMO and a decrease of WF result in unconventional downward band bending and decreased ionization potential (IP). The correlations of the orientation ordering of molecules, film growth and interface electronic structures provide a useful design strategy to improve the performance of C8-BTBT thin film based field effect transistors.

Antileishmanial activities of dihydrochalcones from piper elongatum and synthetic related compounds. Structural requirements for activity.

PubMed

Hermoso, Alicia; Jiménez, Ignacio A; Mamani, Zulma A; Bazzocchi, Isabel L; Piñero, José E; Ravelo, Angel G; Valladares, Basilio

2003-09-01

Two dihydrochalcones (1 and 2) were isolated from Piper elongatum Vahl by activity-guided fractionation against extracellular promastigotes of Leishmania braziliensis in vitro. Their structures were elucidated by spectral analysis, including homonuclear and heteronuclear correlation NMR experiments. Derivatives 3-7 and 20 synthetic related compounds (8-27) were also assayed to establish the structural requirements for antileishmanial activity. Compounds 1-11 that proved to be more active that ketoconazol, used as positive control, were further assayed against promastigotes of Leishmania tropica and Leishmania infantum. Compounds 7 and 11, with a C(6)-C(3)-C(6) system, proved to be the most promising compounds, with IC(50) values of 2.98 and 3.65 microg/mL, respectively, and exhibited no toxic effect on macrophages (around 90% viability). Correlation between the molecular structures and antileishmanial activity is discussed in detail.

Novel aldehyde and thiosemicarbazone derivatives: Synthesis, spectroscopic characterization, structural studies and molecular docking studies

NASA Astrophysics Data System (ADS)

Karakurt, Tuncay; Tahtaci, Hakan; Subasi, Nuriye Tuna; Er, Mustafa; Ağar, Erbil

2016-12-01

In this study our purpose is that, synthesis and characterization of compounds containing the aldehyde and thiosemicarbazone groups and comparison of the theoretical results with the experimental results. The structures of all synthesized compounds were elucidated by IR, 1H NMR, 13C NMR, elemental analyses techniques. The structure of compound (4) (C9H8N4O2S) was also elucidated by X-ray diffraction analysis. In addition, the theoretical IR spectrum, 1H NMR and 13C NMR chemical shift values, frontier molecular orbital values (FMO) of these molecules were analyzed by using Becke-3- Lee-Yang-Parr (B3LYP) method with LanL2DZ basis set. Finally, molecular docking studies were performed on synthesized compounds using the 4DKI beta-lactam protein structure to determine the potential binding mode of inhibitors.

First-principle study of structural, electronic and magnetic properties of (FeC)n (n = 1-8) and (FeC)8TM (TM = V, Cr, Mn and Co) clusters.

PubMed

Li, Cheng-Gang; Zhang, Jie; Zhang, Wu-Qin; Tang, Ya-Nan; Ren, Bao-Zeng; Hu, Yan-Fei

2017-12-13

The structural, electronic and magnetic properties of the (FeC) n (n = 1-8) clusters are studied using the unbiased CALYPSO structure search method and density functional theory. A combination of the PBE functional and 6-311 + G* basis set is used for determining global minima on potential energy surfaces of (FeC) n clusters. Relatively stabilities are analyzed via computing their binding energies, second order difference and HOMO-LUMO gaps. In addition, the origin of magnetic properties, spin density and density of states are discussed in detail, respectively. At last, based on the same computational method, the structures, magnetic properties and density of states are systemically investigated for the 3d (V, Cr, Mn and Co) atom doped (FeC) 8 cluster.

A STUDY OF THE η^'π^- SYSTEM PRODUCED IN THE REACTION π^-parrowη^'π^- p AT 18 GeV/c

NASA Astrophysics Data System (ADS)

Ivanov-Tatar, Emil

2000-04-01

The η^'π^- system has been studied in the reaction π^-parrowη^'π^- p at 18 GeV/c. The partial wave analysis of 6040 kinematically-identified events shows that the reaction is dominated by natural parity exchange. The production of an exotic isovector state π_1(1600) is observed in the I^G(J^PC) = 1^-(1^-+) wave. The mass and the width of that state are estimated via simultaneous mass-dependent fits of the I^G(J^PC) = 1^-(1^-+) and I^G(J^PC) = 1^-(2^++) waves. The a_2^-(1320) and a wide structure at 1.8 GeV/c^2 are observed in the I^G(J^PC) = 1^-(2^++) wave. The amplitude analysis of the mass interval above 1.8 GeV/c^2 indicates an interference between I^G(J^PC) = 1^-(2^++) and I^G(J^PC) = 1^-(4^++) waves.

Synthesis, structure, spectral characterization and thermal analysis of the tetraaquabis (isothiocyanato-κN) cobalt (II)-bis(caffeine)-tetrahydrate complex

NASA Astrophysics Data System (ADS)

EL Hamdani, H.; EL Amane, M.; Duhayon, C.

2018-04-01

The complex 2(C8H10N4O2).[Co(H2O)4(NCS)2].4H2O was prepared in the water-ethanol solution at room temperature and characterized by the single crystal X-ray diffraction analysis, 1H, 13C NMR, TGA/DTA and IR spectroscopy. This complex was crystallized in the monoclinic system (P 21/c). The unit cell parameters are a = 10.65854 (19) A°, b = 8.16642 (14) A°, c = 18.0595 (3) A° with β = 96.4701° (15). The cobalt (II) cation is coordinated by four oxygen atoms of the water molecules and two nitrogen in isothiocyanato a trans octahedral geometry, stabilized by hydrogen bonds with caffeine molecule and free water molecule, The intermolecular hydrogen bonds: Osbnd H⋯N, Osbnd H⋯O, Csbnd H⋯S, π···π interactions are together playing a vital role in the stabilization of the crystal packing.

Synthesis, structural characterization and density functional studies of ethyl 4-(biphenyl-4-yl)-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate A non-merohedral twinned structure

NASA Astrophysics Data System (ADS)

Yıdırım, Sema Öztürk; Büyükmumcu, Zeki; Butcher, Ray J.; Çetin, Gökalp; Şimşek, Rahime; Şafak, Cihat

2018-07-01

1,4-Dihydropyridine (1,4-DHP) derivatives have the reducing effect of extracellular Ca2+ ions influx on the L-type calcium channel. Because of this effect many 1,4-DHP derivatives are potent calcium channel blockers and antihypertensive agents. The biphenyl group is present in the structures of the most biologically active compounds and thus is an important group. By introducing this moiety into the structure of various compounds, active compounds are obtained. Thus, pharmacologically active structures can be condensed with the biphenyl structure to achieve novel biologically active compounds or compounds with increased activity. In this study, to achieve an active calcium channel blocker compound, the biphenyl group was introduced into the 1,4-DHP structure. The structure of the compound is proved by IR, 1H NMR, Mass spectroscopy, X-ray crystallography and elemental analysis. The cytotoxic activity assays have continued and positive results have been obtained. The phenyl rings [C16-C21 and C22-C27] make dihedral angles of 84.4 (1) and 87.5 (1)°, respectively, with the 1,4-dihydropyridine ring [N1/C1/C4-C9]. In the crystal, adjacent molecules are linked by Nsbnd H … O and Csbnd H … O hydrogen bonds into chains parallel to [010].

Practical Application of Finite Element Analysis to Aircraft Structural Design

DTIC Science & Technology

1986-08-01

at the design stage AEROELASTICITE ET OPTIMISATION EN AVANT-PROJET (AA)PETIAU, C; (AB) BOUTIN , D. Avions Marcel Dassault-Breguet Aviation, Saint...Interscience, 1981, p. 431-443. 810000 p. 13 refs 8 In: EN (English) p. 2018 The design complexity and size of convectively-cooled engine and airframe

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

Thimmaiah, Srinivasa; Tener, Zachary; Lamichhane, Tej N.

Here, the γ-region of the Mn–Al phase diagram between 45 and 70 at.% Al was re-investigated by a combination of powder and single crystal X-ray diffraction as well as EDS analysis to establish the distribution of Mn and Al atoms. Single crystals of γ-Mn 5–x Al 8+x were grown using Sn-flux at 650 °C. The crystal structure, atomic coordinates and site occupancy parameters of γ-Mn 5–x Al 8+x phases were refined from single crystal X-ray data. The γ-Mn 5-x Al 8+x phase adopts the rhombohedral Cr 5Al 8-type structure rather than a cubic γ-brass structure. The refined compositions from twomore » crystals extracted from the Al-rich and Mn-rich sides are, respectively, Mn 4.76Al 8.24(2) (I) and Mn 6.32Al 6.68(2) (II). The structure was refined in the acentric R3m space group (No.160, Z=6), in order to compare with other reported rhombohedral γ-brasses. In addition, according to X-ray powder diffraction analysis, at the Al-rich side the γ-phase coexists with LT–Mn 4Al 11 and, at the Mn-rich side, with a hitherto unknown phase. The refined lattice parameters from powder patterns fall in the range a=12.6814(7)–12.6012(5) Å and c=7.9444(2)–7.9311(2) Å from Al-rich to Mn-rich loadings, and the corresponding rhombohedral angles distorted from a pseudo-cubic cell were found to be 89.1(1)°–88.9(1)°. Magnetic susceptibility and magnetization studies of Mn 4.92Al 8.08(2) are consistent with moment bearing Mn and suggest a spin glass state below 27 K. Tight-binding electronic structure calculations (LMTO-ASA with LSDA) showed that the calculated Fermi level for γ-“Mn 5Al 8” falls within a pseudogap of the density of states, a result which is in accordance with a Hume-Rothery stabilization mechanism γ-brass type phases.« less

Newly assigned microwave transitions and a global analysis of the combined microwave/millimeter wave rotational spectra of 9-fluorenone and benzophenone

NASA Astrophysics Data System (ADS)

West, Channing; Sedo, Galen; van Wijngaarden, Jennifer

2017-05-01

Microwave spectra of 9-fluorenone and benzophenone have been observed using a broadband chirped-pulse Fourier Transform Microwave (cp-FTMW) Spectrometer. An analysis of the microwave spectra allowed for the assignment of 178 b-type rotational transitions for 9-fluorenone in the 8.0-13.0 GHz region, the assignment of 166 b-type transitions for benzophenone in the 8.0-14.0 GHz region, and effectively quadrupled the total number of pure rotational transitions observed for these molecules. This new microwave data and the previously published millimeter wave data of Maris et al. have been analyzed together in a global fit, where the resulting rotational constants accurately reproduce the spectra over the entire 8-80 GHz region for both molecules. In addition, the resulting constants have been found to be consistent with the expected planar C2v structure for 9-fluorenone and the paddle-wheel like C2 structure of benzophenone. The rotational constants of the combined global fit have allowed for a more precise determination of the inertial defects (Δ) and second moments of inertia (Pcc) for 9-fluoreneone and benzophenone. Specific focus has been paid to the second moment of benzophenone, which when used in conjunction with theory strongly suggests an ∼32.9° torsional angle out of the ab-plane for the paddle-wheel structure of the gas-phase molecule.

An Approach to Knowledge-Directed Image Analysis,

DTIC Science & Technology

1977-09-01

34AN APPROACH TO KNOWLEDGE -DIRECTED IMAGE ANALYSIS D.H. Ballard, C.M.’Brown, J.A. Feldman Computer Science Department iThe University of Rochester...Rochester, New York 14627 DTII EECTE UTIC FILE COPY o n I, n 83 - ’ f t 8 11 28 19 1f.. AN APPROACH TO KNOWLEDGE -DIRECTED IMAGE ANALYSIS 5*., D.H...semantic network model and a distributed control structure to accomplish the image analysis process. The process of " understanding an image" leads to

A Survey of Probabilistic Methods for Dynamical Systems with Uncertain Parameters.

DTIC Science & Technology

1986-05-01

J., "An Approach to the Theoretical Background of Statistical Energy Analysis Applied to Structural Vibration," Journ. Acoust. Soc. Amer., Vol. 69...1973, Sect. 8.3. 80. Lyon, R.H., " Statistical Energy Analysis of Dynamical Systems," M.I.T. Press, 1975. e) Late References added in Proofreading !! 81...Dowell, E.H., and Kubota, Y., "Asymptotic Modal Analysis and ’~ y C-" -165- Statistical Energy Analysis of Dynamical Systems," Journ. Appi. - Mech

Interpenetration of a 3D Icosahedral M@Ni12 (M=Al, Ga) Framework with Porphyrin-Reminiscent Boron Layers in MNi9 B8.

PubMed

Zheng, Qiang; Wagner, Frank R; Ormeci, Alim; Prots, Yurii; Burkhardt, Ulrich; Schmidt, Marcus; Schnelle, Walter; Grin, Yuri; Leithe-Jasper, Andreas

2015-11-09

Two ternary borides MNi9 B8 (M=Al, Ga) were synthesized by thermal treatment of mixtures of the elements. Single-crystal X-ray diffraction data reveal AlNi9 B8 and GaNi9 B8 crystallizing in a new type of structure within the space group Cmcm and the lattice parameters a=7.0896(3) Å, b=8.1181(3) Å, c=10.6497(4) Å and a=7.0897(5) Å, b=8.1579(4) Å, c=10.6648(7) Å, respectively. The boron atoms build up two-dimensional layers, which consist of puckered [B16 ] rings with two tailing B atoms, whereas the M atoms reside in distorted vertices-condensed [Ni12 ] icosahedra, which form a three-dimensional framework interpenetrated by boron porphyrin-reminiscent layers. An unusual local arrangement resembling a giant metallo-porphyrin entity is formed by the [B16 ] rings, which, due to their large annular size of approximately 8 Å, chelate four of the twelve icosahedral Ni atoms. An analysis of the chemical bonding by means of the electron localizability approach reveals strong covalent B-B interactions and weak Ni-Ni interactions. Multi-center dative B-Ni interaction occurs between the Al-Ni framework and the boron layers. In agreement with the chemical bonding analysis and band structure calculations, AlNi9 B8 is a Pauli-paramagnetic metal. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Structural characterization of β-ketoiminate-stabilized gallium hydrides for chemical vapor deposition applications.

PubMed

Marchand, Peter; Pugh, David; Parkin, Ivan P; Carmalt, Claire J

2014-08-11

Bis-β-ketoimine ligands of the form [(CH2 )n {N(H)C(Me)CHC(Me)O}2 ] (L(n) H2 , n=2, 3 and 4) were employed in the formation of a range of gallium complexes [Ga(L(n) )X] (X=Cl, Me, H), which were characterised by NMR spectroscopy, mass spectrometry and single-crystal X-ray diffraction analysis. The β-ketoimine ligands have also been used for the stabilisation of rare gallium hydride species [Ga(L(n) )H] (n=2 (7); n=3 (8)), which have been structurally characterised for the first time, confirming the formation of five-coordinate, monomeric species. The stability of these hydrides has been probed through thermal analysis, revealing stability at temperatures in excess of 200 °C. The efficacy of all the gallium β-ketoiminate complexes as molecular precursors for the deposition of gallium oxide thin films by chemical vapour deposition (CVD) has been investigated through thermogravimetric analysis and deposition studies, with the best results being found for a bimetallic gallium methyl complex [L(3) {GaMe2 }2 ] (5) and the hydride [Ga(L(3) )H] (8). The resulting films (F5 and F8, respectively) were amorphous as-deposited and thus were characterised primarily by XPS, EDXA and SEM techniques, which showed the formation of stoichiometric (F5) and oxygen-deficient (F8) Ga2 O3 thin films. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

All-atomic Molecular Dynamic Studies of Human CDK8: Insight into the A-loop, Point Mutations and Binding with Its Partner CycC

PubMed Central

Xu, Wu; Amire-Brahimi, Benjamin; Xie, Xiao-Jun; Huang, Liying; Ji, Jun-Yuan

2014-01-01

The Mediator, a conserved multisubunit protein complex in eukaryotic organisms, regulates gene expression by bridging sequence-specific DNA-binding transcription factors to the general RNA polymerase II machinery. In yeast, Mediator complex is organized in three core modules (head, middle and tail) and a separable ‘CDK8 submodule’ consisting of four subunits including Cyclin-dependent kinase CDK8 (CDK8), Cyclin C (CycC), MED12, and MED13. The 3-D structure of human CDK8-CycC complex has been recently experimentally determined. To take advantage of this structure and the improved theoretical calculation methods, we have performed molecular dynamic simulations to study dynamics of CDK8 and two CDK8 point mutations (D173A and D189N), which have been identified in human cancers, with and without full length of the A-loop as well as the binding between CDK8 and CycC. We found that CDK8 structure gradually loses two helical structures during the 50-ns molecular dynamic simulation, likely due to the presence of the full-length A-loop. In addition, our studies showed the hydrogen bond occupation of the CDK8 A-loop increases during the first 20-ns MD simulation and stays stable during the later 30-ns MD simulation. Four residues in the A-loop of CDK8 have high hydrogen bond occupation, while the rest residues have low or no hydrogen bond occupation. The hydrogen bond dynamic study of the A-loop residues exhibits three types of changes: increasing, decreasing, and stable. Furthermore, the 3-D structures of CDK8 point mutations D173A, D189N, T196A and T196D have been built by molecular modeling and further investigated by 50-ns molecular dynamic simulations. D173A has the highest average potential energy, while T196D has the lowest average potential energy, indicating that T196D is the most stable structure. Finally, we calculated theoretical binding energy of CDK8 and CycC by MM/PBSA and MM/GBSA methods, and the negative values obtained from both methods demonstrate stability of CDK8-CycC complex. Taken together, these analyses will improve our understanding of the exact functions of CDK8 and the interaction with its partner CycC. PMID:24754906

Altered Pre-mRNA Splicing Caused by a Novel Intronic Mutation c.1443+5G>A in the Dihydropyrimidinase (DPYS) Gene

PubMed Central

Nakajima, Yoko; Meijer, Judith; Zhang, Chunhua; Wang, Xu; Kondo, Tomomi; Ito, Tetsuya; Dobritzsch, Doreen; Van Kuilenburg, André B. P.

2016-01-01

Dihydropyrimidinase (DHP) deficiency is an autosomal recessive disease caused by mutations in the DPYS gene. Patients present with highly elevated levels of dihydrouracil and dihydrothymine in their urine, blood and cerebrospinal fluid. The analysis of the effect of mutations in DPYS on pre-mRNA splicing is hampered by the fact that DHP is primarily expressed in liver and kidney cells. The minigene approach can detect mRNA splicing aberrations using cells that do not express the endogenous mRNA. We have used a minigene-based approach to analyze the effects of a presumptive pre-mRNA splicing mutation in two newly identified Chinese pediatric patients with DHP deficiency. Mutation analysis of DPYS showed that both patients were compound heterozygous for a novel intronic mutation c.1443+5G>A in intron 8 and a previously described missense mutation c.1001A>G (p.Q334R) in exon 6. Wild-type and the mutated minigene constructs, containing exons 7, 8 and 9 of DPYS, yielded different splicing products after expression in HEK293 cells. The c.1443+5G>A mutation resulted in altered pre-mRNA splicing of the DPYS minigene construct with full skipping of exon 8. Analysis of the DHP crystal structure showed that the deletion of exon 8 severely affects folding, stability and homooligomerization of the enzyme as well as disruption of the catalytic site. Thus, the analysis suggests that the c.1443+5G>A mutation results in aberrant splicing of the pre-mRNA encoding DHP, underlying the DHP deficiency in two unrelated Chinese patients. PMID:26771602

Altered Pre-mRNA Splicing Caused by a Novel Intronic Mutation c.1443+5G>A in the Dihydropyrimidinase (DPYS) Gene.

PubMed

Nakajima, Yoko; Meijer, Judith; Zhang, Chunhua; Wang, Xu; Kondo, Tomomi; Ito, Tetsuya; Dobritzsch, Doreen; Van Kuilenburg, André B P

2016-01-12

Dihydropyrimidinase (DHP) deficiency is an autosomal recessive disease caused by mutations in the DPYS gene. Patients present with highly elevated levels of dihydrouracil and dihydrothymine in their urine, blood and cerebrospinal fluid. The analysis of the effect of mutations in DPYS on pre-mRNA splicing is hampered by the fact that DHP is primarily expressed in liver and kidney cells. The minigene approach can detect mRNA splicing aberrations using cells that do not express the endogenous mRNA. We have used a minigene-based approach to analyze the effects of a presumptive pre-mRNA splicing mutation in two newly identified Chinese pediatric patients with DHP deficiency. Mutation analysis of DPYS showed that both patients were compound heterozygous for a novel intronic mutation c.1443+5G>A in intron 8 and a previously described missense mutation c.1001A>G (p.Q334R) in exon 6. Wild-type and the mutated minigene constructs, containing exons 7, 8 and 9 of DPYS, yielded different splicing products after expression in HEK293 cells. The c.1443+5G>A mutation resulted in altered pre-mRNA splicing of the DPYS minigene construct with full skipping of exon 8. Analysis of the DHP crystal structure showed that the deletion of exon 8 severely affects folding, stability and homooligomerization of the enzyme as well as disruption of the catalytic site. Thus, the analysis suggests that the c.1443+5G>A mutation results in aberrant splicing of the pre-mRNA encoding DHP, underlying the DHP deficiency in two unrelated Chinese patients.

Catenanes: A molecular mechanics analysis of the (C13H26)2 Structure 13-13 D2.

PubMed

Lii, Jenn-Huei; Allinger, Norman L; Hu, Ching-Han; Schaefer, Henry F

2016-01-05

Molecular mechanics (MM4) studies have been carried out on the catenane (C13H26)2, specifically 13-13D2. The structure obtained is in general agreement with second-order perturbation theory. More importantly, the MM4 structure allows a breakdown of the energy of the molecule into its component classical parts. This allows an understanding of why the structure is so distorted, in terms of C-C bonding and nonbonding interactions, van der Waals repulsion, C-C-C and C-C-H angle bending, torsional energies, stretch-bend, torsion-stretch, and bend-torsion-bend interactions. Clearly, the hole in 113-membered ring is too small for the other ring to fit through comfortably. There are too many atoms trying to fit into the limited space at the same time, leading to large van der Waals repulsions. The rings distort in such a way as to enlarge this available space, and lower the total energy of the molecule. While the distortions are spread around the rings, one of the nominally tetrahedral C-C-C bond angles in each ring is opened to 147.9° by MM4 (146.8° by MP2). The stability of the compound is discussed in terms of the strain energy. © 2015 Wiley Periodicals, Inc.

A phase transition caught in mid-course: independent and concomitant analyses of the monoclinic and triclinic structures of (nBu4N)[Co(orotate)2(bipy)]·3H2O.

PubMed

Castro, Miguel; Falvello, Larry R; Forcén-Vázquez, Elena; Guerra, Pablo; Al-Kenany, Nuha A; Martínez, Gema; Tomás, Milagros

2017-09-01

The preparation and characterization of the n Bu 4 N + salts of two bis-orotate(2-) complexes of cobalt, namely bis(tetra-n-butylammonium) diaquabis(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κ 2 N 1 ,O 6 )cobalt(II) 1.8-hydrate, (C 16 H 36 N) 2 [Co(C 5 H 2 N 2 O 4 ) 2 (H 2 O) 2 ]·1.8H 2 O, (1), and tetra-n-butylammonium (2,2'-bipyridine-κ 2 N,N')bis(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κ 2 N 1 ,O 6 )cobalt(III) trihydrate, (C 16 H 36 N)[Co(C 5 H 2 N 2 O 4 ) 2 (C 10 H 8 N 2 )]·3H 2 O, (2), are reported. The Co III complex, (2), which is monoclinic at room temperature, presents a conservative single-crystal-to-single-crystal phase transition below 200 K, producing a triclinic twin. The transition, which involves a conformational change in one of the n Bu groups of the cation, is reversible and can be cycled. Both end phases have been characterized structurally and the system was also characterized structurally in a two-phase intermediate state, using single-crystal diffraction techniques, with both the monoclinic and triclinic phases present. Thermal analysis allows a rough estimate of the small energy content, viz. 0.25 kJ mol -1 , for both the monoclinic-to-triclinic transformation and the reverse transition, in agreement with the nature of the structural changes involving only the n Bu 4 N + cation.

Counting individual sulfur atoms in a protein by ultrahighresolution Fourier transform ion cyclotron resonance mass spectrometry: Experimental resolution of isotopic fine structure in proteins

PubMed Central

Shi, Stone D.-H.; Hendrickson, Christopher L.; Marshall, Alan G.

1998-01-01

A typical molecular ion mass spectrum consists of a sum of signals from species of various possible isotopic compositions. Only the monoisotopic peak (e.g., all carbons are 12C; all nitrogens are 14N, etc.) has a unique elemental composition. Every other isotope peak at approximately integer multiples of ∼1 Da higher in nominal mass represents a sum of contributions from isotope combinations differing by a few mDa (e.g., two 13C vs. two 15N vs. one 13C and one 15N vs. 34S, vs. 18O, etc., at ∼2 Da higher in mass than the monoisotopic mass). At sufficiently high mass resolving power, each of these nominal-mass peaks resolves into its isotopic fine structure. Here, we report resolution of the isotopic fine structure of proteins up to 15.8 kDa (isotopic 13C,15N doubly depleted tumor suppressor protein, p16), made possible by electrospray ionization followed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass analysis at 9.4 tesla. Further, a resolving power of m/Δm50% ≈8,000,000 has been achieved on bovine ubiquitin (8.6 kDa). These results represent a 10-fold increase in the highest mass at which isotopic fine structure previously had been observed. Finally, because isotopic fine structure reveals elemental composition directly, it can be used to confirm or determine molecular formula. For p16, for example, we were able to determine (5.1 ± 0.3) the correct number (five) of sulfur atoms solely from the abundance ratio of the resolved 34S peak to the monoisotopic peak. PMID:9751700

The haloarchaeal MCM proteins: bioinformatic analysis and targeted mutagenesis of the β7-β8 and β9-β10 hairpin loops and conserved zinc binding domain cysteines.

PubMed

Kristensen, Tatjana P; Maria Cherian, Reeja; Gray, Fiona C; MacNeill, Stuart A

2014-01-01

The hexameric MCM complex is the catalytic core of the replicative helicase in eukaryotic and archaeal cells. Here we describe the first in vivo analysis of archaeal MCM protein structure and function relationships using the genetically tractable haloarchaeon Haloferax volcanii as a model system. Hfx. volcanii encodes a single MCM protein that is part of the previously identified core group of haloarchaeal MCM proteins. Three structural features of the N-terminal domain of the Hfx. volcanii MCM protein were targeted for mutagenesis: the β7-β8 and β9-β10 β-hairpin loops and putative zinc binding domain. Five strains carrying single point mutations in the β7-β8 β-hairpin loop were constructed, none of which displayed impaired cell growth under normal conditions or when treated with the DNA damaging agent mitomycin C. However, short sequence deletions within the β7-β8 β-hairpin were not tolerated and neither was replacement of the highly conserved residue glutamate 187 with alanine. Six strains carrying paired alanine substitutions within the β9-β10 β-hairpin loop were constructed, leading to the conclusion that no individual amino acid within that hairpin loop is absolutely required for MCM function, although one of the mutant strains displays greatly enhanced sensitivity to mitomycin C. Deletions of two or four amino acids from the β9-β10 β-hairpin were tolerated but mutants carrying larger deletions were inviable. Similarly, it was not possible to construct mutants in which any of the conserved zinc binding cysteines was replaced with alanine, underlining the likely importance of zinc binding for MCM function. The results of these studies demonstrate the feasibility of using Hfx. volcanii as a model system for reverse genetic analysis of archaeal MCM protein function and provide important confirmation of the in vivo importance of conserved structural features identified by previous bioinformatic, biochemical and structural studies.

Spoxazomicin D and Oxachelin C, Potent Neuroprotective Carboxamides from the Appalachian Coal Fire-Associated Isolate Streptomyces sp. RM-14-6.

PubMed

Shaaban, Khaled A; Saunders, Meredith A; Zhang, Yinan; Tran, Tuan; Elshahawi, Sherif I; Ponomareva, Larissa V; Wang, Xiachang; Zhang, Jianjun; Copley, Gregory C; Sunkara, Manjula; Kharel, Madan K; Morris, Andrew J; Hower, James C; Tremblay, Matthew S; Prendergast, Mark A; Thorson, Jon S

2017-01-27

The isolation and structure elucidation of six new bacterial metabolites [spoxazomicin D (2), oxachelins B and C (4, 5), and carboxamides 6-8] and 11 previously reported bacterial metabolites (1, 3, 9-12a, and 14-18) from Streptomyces sp. RM-14-6 is reported. Structures were elucidated on the basis of comprehensive 1D and 2D NMR and mass spectrometry data analysis, along with direct comparison to synthetic standards for 2, 11, and 12a,b. Complete 2D NMR assignments for the known metabolites lenoremycin (9) and lenoremycin sodium salt (10) were also provided for the first time. Comparative analysis also provided the basis for structural revision of several previously reported putative aziridine-containing compounds [exemplified by madurastatins A1, B1, C1 (also known as MBJ-0034), and MBJ-0035] as phenol-dihydrooxazoles. Bioactivity analysis [including antibacterial, antifungal, cancer cell line cytotoxicity, unfolded protein response (UPR) modulation, and EtOH damage neuroprotection] revealed 2 and 5 as potent neuroprotectives and lenoremycin (9) and its sodium salt (10) as potent UPR modulators, highlighting new functions for phenol-oxazolines/salicylates and polyether pharmacophores.

Thiocyanate-Ligated Heterobimetallic {PtM} Lantern Complexes Including a Ferromagnetically Coupled 1D Coordination Polymer.

PubMed

Guillet, Jesse L; Bhowmick, Indrani; Shores, Matthew P; Daley, Christopher J A; Gembicky, Milan; Golen, James A; Rheingold, Arnold L; Doerrer, Linda H

2016-08-15

A series of heterobimetallic lantern complexes with the central unit {PtM(SAc)4(NCS)} have been prepared and thoroughly characterized. The {Na(15C5)}[PtM(SAc)4(NCS)] series, 1 (Co), 2 (Ni), 3 (Zn), are discrete compounds in the solid state, whereas the {Na(12C4)2)}[PtM(SAc)4(NCS)] series, 4 (Co), 5 (Ni), 6 (Zn), and 7 (Mn), are ion-separated species. Compound 7 is the first {PtMn} lantern of any bridging ligand (carboxylate, amide, etc.). Monomeric 1-7 have M(2+), necessitating counter cations that have been prepared as {(15C5)Na}(+) and {(12C4)2Na}(+) variants, none of which form extended structures. In contrast, neutral [PtCr(tba)4(NCS)]∞ 8 forms a coordination polymer of {PtCr}(+) units linked by (NCS)(-) in a zigzag chain. All eight compounds have been thoroughly characterized and analyzed in comparison to a previously reported family of compounds. Crystal structures are presented for compounds 1-6 and 8, and solution magnetic susceptibility measurements are presented for compounds 1, 2, 4, 5, and 7. Further structural analysis of dimerized {PtM} units reinforces the empirical observation that greater charge density along the Pt-M vector leads to more Pt···Pt interactions in the solid state. Four structural classes, one new, of {MPt}···{PtM} units are presented. Solid state magnetic characterization of 8 reveals a ferromagnetic interaction in the {PtCr(NCS)} chain between the Cr centers of J/kB = 1.7(4) K.

13C and 19F solid-state NMR and X-ray crystallographic study of halogen-bonded frameworks featuring nitrogen-containing heterocycles.

PubMed

Szell, Patrick M J; Gabriel, Shaina A; Gill, Russell D D; Wan, Shirley Y H; Gabidullin, Bulat; Bryce, David L

2017-03-01

Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ-hole) and an electron donor. We report a crystallographic and structural analysis of halogen-bonded compounds by applying a combined X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) approach. Single-crystal XRD was first used to characterize the halogen-bonded cocrystals formed between two fluorinated halogen-bond donors (1,4-diiodotetrafluorobenzene and 1,3,5-trifluoro-2,4,6-triiodobenzene) and several nitrogen-containing heterocycles (acridine, 1,10-phenanthroline, 2,3,5,6-tetramethylpyrazine, and hexamethylenetetramine). New structures are reported for the following three cocrystals, all in the P2 1 /c space group: acridine-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 13 H 9 N, 1,10-phenanthroline-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 12 H 8 N 2 , and 2,3,5,6-tetramethylpyrazine-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 8 H 12 N 2 . 13 C and 19 F solid-state magic-angle spinning (MAS) NMR is shown to be a convenient method to characterize the structural features of the halogen-bond donor and acceptor, with chemical shifts attributable to cocrystal formation observed in the spectra of both nuclides. Cross polarization (CP) from 19 F to 13 C results in improved spectral sensitivity in characterizing the perfluorinated halogen-bond donor when compared to conventional 1 H CP. Gauge-including projector-augmented wave density functional theory (GIPAW DFT) calculations of magnetic shielding constants, along with optimization of the XRD structures, provide a final set of structures in best agreement with the experimental 13 C and 19 F chemical shifts. Data for carbons bonded to iodine remain outliers due to well-known relativistic effects.

R2C: improving ab initio residue contact map prediction using dynamic fusion strategy and Gaussian noise filter.

PubMed

Yang, Jing; Jin, Qi-Yu; Zhang, Biao; Shen, Hong-Bin

2016-08-15

Inter-residue contacts in proteins dictate the topology of protein structures. They are crucial for protein folding and structural stability. Accurate prediction of residue contacts especially for long-range contacts is important to the quality of ab inito structure modeling since they can enforce strong restraints to structure assembly. In this paper, we present a new Residue-Residue Contact predictor called R2C that combines machine learning-based and correlated mutation analysis-based methods, together with a two-dimensional Gaussian noise filter to enhance the long-range residue contact prediction. Our results show that the outputs from the machine learning-based method are concentrated with better performance on short-range contacts; while for correlated mutation analysis-based approach, the predictions are widespread with higher accuracy on long-range contacts. An effective query-driven dynamic fusion strategy proposed here takes full advantages of the two different methods, resulting in an impressive overall accuracy improvement. We also show that the contact map directly from the prediction model contains the interesting Gaussian noise, which has not been discovered before. Different from recent studies that tried to further enhance the quality of contact map by removing its transitive noise, we designed a new two-dimensional Gaussian noise filter, which was especially helpful for reinforcing the long-range residue contact prediction. Tested on recent CASP10/11 datasets, the overall top L/5 accuracy of our final R2C predictor is 17.6%/15.5% higher than the pure machine learning-based method and 7.8%/8.3% higher than the correlated mutation analysis-based approach for the long-range residue contact prediction. http://www.csbio.sjtu.edu.cn/bioinf/R2C/Contact:hbshen@sjtu.edu.cn Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Highly (002) textured large grain bcc Cr{sub 80}Mn{sub 20} seed layer on Cr{sub 50}Ti{sub 50} amorphous layer for FePt-C granular film

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

Jeon, Seong-Jae, E-mail: jsjigst@ecei.tohoku.ac.jp; Saito, Shin; Hinata, Shintaro

Effect of bcc Cr{sub 80}Mn{sub 20} seed layer and Cr{sub 50}Ti{sub 50} amorphous texture inducing layer on the heteroepitaxy system in FePt-C granular film was studied by introducing a new concept of the layered structure. The concept suggested that the large grain seed layer in which the crystallographic texture was initially formed on an amorphous layer in the layered structure can reduce the angular distribution of (002) c-axis crystal orientation in the FePt-C granular film owing to heteroepitaxial growth. Structure analysis by X-ray diffraction revealed that (1) when the substrate heating temperature was elevated from 300 °C to 500 °C, grain sizemore » in the seed layer increased from 9.8 nm to 11.6 nm, and then decreased with further increasing the substrate temperature. The reduction of the grain size over 500 °C corresponds to the crystallization of the amorphous texture inducing layer, (2) when the grain size increased from 9.8 nm to 11.6 nm, the angular distribution of the (002) orientation in the seed layer dramatically decreased from 13.7° to 4.1°. It was shown that the large grain seed layer increased the perpendicular hysteresis in FePt-C granular film.« less

Synthesis, structures, and photophysical properties of π-expanded oligothiophene 8-mers and their Saturn-like C₆₀ complexes.

PubMed

Shimizu, Hideyuki; Cojal González, José D; Hasegawa, Masashi; Nishinaga, Tohru; Haque, Tahmina; Takase, Masayoshi; Otani, Hiroyuki; Rabe, Jürgen P; Iyoda, Masahiko

2015-03-25

Two isomers of a multifunctional π-expanded macrocyclic oligothiophene 8-mer, E,E-1 and Z,Z-1, were synthesized using a McMurry coupling of a dialdehyde composed of four 2,5-thienylene and three ethynylene units under high dilution conditions. On the other hand, cyclo[8](2,5-thienylene-ethynylene) 2 was synthesized by intramolecular Sonogashira cyclization of ethynyl bromide 5. From STM measurements, both E,E-1 and Z,Z-1 formed self-assembled monolayers at the solid-liquid interface to produce porous networks, and from X-ray analyses of E,E-1 and 2, both compounds had a round shape with a honeycomb stacked structure. E,E-1 formed various fibrous polymorphs due to nanophase separation of the macrorings. E,E-1 and Z,Z-1 in solution exhibited photochromism upon irradiation with visible and UV light, respectively, and this photoisomerization was confirmed by using STM. Furthermore, amorphous films of Z,Z-1 and E,E-1 showed photoisomerization, although single crystals, fibers, and square tubes of E,E-1 remained unchanged under similar conditions. E,E-1 with a 12.5-14.7 Å inner cavity incorporated fullerene C60 in the cavity in solution and the solid state to produce a Saturn-like complex, whose structure was determined by X-ray analysis. 2 also formed a Saturn-like complex with C60 in the solid state. These Saturn-like complexes are stabilized by van der Waals interactions between the sulfur atoms of 8-mer and C60. The complexes exhibited charge-transfer interactions in the solid state. Like E,E-1, Saturn-like complex E,E-1⊃C60 formed small cube and fiber structures depending on the solvent used, whereas those of Saturn-like complex 2⊃C60 were limited due to the rigidity of the macroring of 2.

Structural Analysis of Proteins in Extreme Saline Environments

DTIC Science & Technology

1989-03-16

ferredoxinz with the same 2Fe-2S prosthetic group trom the blue-green algae Spirulina platensis (SplFd) (K. Fukuyama et al., 1980; Tsukihara et al...8 b) Molecular Conformation of 2Fe-2S Ferredoxin....................................9 c) Similarity to 2Fe-2S Ferredoxin from Spiruifina platensis ...ferredoxin from Peptococcus aerogenes (Adman, Sicker & Jensen, 1972; Carter et al., 1974). c) Similarity to 2Fe-2S Ferredoxin from Svindina platensis The

A New Ergosterol Analog, a New Bis-Anthraquinone and Anti-Obesity Activity of Anthraquinones from the Marine Sponge-Associated Fungus Talaromyces stipitatus KUFA 0207

PubMed Central

Noinart, Jidapa; Buttachon, Suradet; Dethoup, Tida; Gales, Luís; Pereira, José A.; Urbatzka, Ralph; Freitas, Sara; Lee, Michael; Silva, Artur M. S.; Pinto, Madalena M. M.; Vasconcelos, Vítor; Kijjoa, Anake

2017-01-01

A new ergosterol analog, talarosterone (1) and a new bis-anthraquinone derivative (3) were isolated, together with ten known compounds including palmitic acid, ergosta-4,6,8(14),22-tetraen-3-one, ergosterol-5,8-endoperoxide, cyathisterone (2), emodin (4a), questinol (4b), citreorosein (4c), fallacinol (4d), rheoemodin (4e) and secalonic acid A (5), from the ethyl acetate extract of the culture of the marine sponge-associated fungus Talaromyces stipitatus KUFA 0207. The structures of the new compounds were established based on extensive 1D and 2D spectral analysis, and in the case of talarosterone (1), the absolute configurations of its stereogenic carbons were determined by X-ray crystallographic analysis. The structure and stereochemistry of cyathisterone (2) was also confirmed by X-ray analysis. The anthraquinones 4a–e and secalonic acid A (5) were tested for their anti-obesity activity using the zebrafish Nile red assay. Only citreorosein (4c) and questinol (4b) exhibited significant anti-obesity activity, while emodin (4a) and secalonic acid A (5) caused toxicity (death) for all exposed zebrafish larvae after 24 h. PMID:28509846

Tautomeric properties, conformations and structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine

NASA Astrophysics Data System (ADS)

Elmali, A.; Kabak, M.; Kavlakoglu, E.; Elerman, Y.; Durlu, T. N.

1999-11-01

The crystal structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine (C 13H 10NO 2Cl) was determined by X-ray analysis. It crystallizes orthorhombic space group P2 12 12 1 with a=12.967(2) Å, b=14.438(3) Å, c=6.231(3) Å, V=1166.5(6) Å 3, Z=4, Dc=1.41 g cm -3 and μ(MoK α)=0.315 mm -1. The title compound is thermochromic and the molecule is nearly planar. Both tautomeric forms (keto and enol forms in 68(3) and 32(3)%, respectively) are present in the solid state. The molecules contain strong intramolecular hydrogen bonds, N1-H1⋯O1/O2 (2.515(1) and 2.581(2) Å) for the keto form and O1-H01⋯N1 for the enol one. There is also strong intermolecular O2-H⋯O1 hydrogen bonding (2.599(2) Å) between neighbouring molecules. Minimum energy conformations AM1 were calculated as a function of the three torsion angles, θ1(N1-C7-C6-C5), θ2(C8-N1-C7-C6) and θ3(C9-C8-N1-C7), varied every 10°. Although the molecule is nearly planar, the AM1 optimized geometry of the title compound is not planar. The non-planar conformation of the title compound corresponding to the optimized X-ray structure is the most stable conformation in all calculations.

Characterization of a novel thermostable Mn(II)-dependent 2,3-dihydroxybiphenyl 1,2-dioxygenase from a polychlorinated biphenyl- and naphthalene-degrading Bacillus sp. JF8.

PubMed

Hatta, Takashi; Mukerjee-Dhar, Gouri; Damborsky, Jiri; Kiyohara, Hohzoh; Kimbara, Kazuhide

2003-06-13

A novel thermostable Mn(II)-dependent 2,3-dihydroxybiphenyl-1,2-dioxygenase (BphC_JF8) catalyzing the meta-cleavage of the hydroxylated biphenyl ring was purified from the thermophilic biphenyl and naphthalene degrader, Bacillus sp. JF8, and the gene was cloned. The native and recombinant BphC enzyme was purified to homogeneity. The enzyme has a molecular mass of 125 +/- 10 kDa and was composed of four identical subunits (35 kDa). BphC_JF8 has a temperature optimum of 85 degrees C and a pH optimum of 7.5. It exhibited a half-life of 30 min at 80 degrees C and 81 min at 75 degrees C, making it the most thermostable extradiol dioxygenase studied. Inductively coupled plasma mass spectrometry analysis confirmed the presence of 4.0-4.8 manganese atoms per enzyme molecule. The EPR spectrum of BphC_JF8 exhibited g = 2.02 and g = 4.06 signals having the 6-fold hyperfine splitting characteristic of Mn(II). The enzyme can oxidize a wide range of substrates, and the substrate preference was in the order 2,3-dihydroxybiphenyl > 3-methylcatechol > catechol > 4-methylcatechol > 4-chlorocatechol. The enzyme is resistant to denaturation by various chelators and inhibitors (EDTA, 1,10-phenanthroline, H2O2, 3-chlorocatechol) and did not exhibit substrate inhibition even at 3 mm 2,3-dihydroxybiphenyl. A decrease in Km accompanied an increase in temperature, and the Km value of 0.095 microm for 2,3-dihydroxybiphenyl (at 60 degrees C) is among the lowest reported. The kinetic properties and thermal stability of the native and recombinant enzyme were identical. The primary structure of BphC_JF8 exhibits less than 25% sequence identity to other 2,3-dihydroxybiphenyl 1,2-dioxygenases. The metal ligands and active site residues of extradiol dioxygenases are conserved, although several amino acid residues found exclusively in enzymes that preferentially cleave bicyclic substrates are missing in BphC_JF8. A three-dimensional homology model of BphC_JF8 provided a basis for understanding the substrate specificity, quaternary structure, and stability of the enzyme.

Statistical Methods for Turbine Blade Dynamics

DTIC Science & Technology

2008-09-30

disks Journal of Sound and Vibration 317 , pp. 625-645. Calanni, G., Volovoi, V., Ruzzene, M, Vining, C., Cento, P., (2007). Application of Bayesian...are investigated for two vibration problems regarding a one-dimensional beam and a three-dimensional plate structure. It is to be noted that the...gaps," Reliability Engi- neering and System Safety, no. 85, pp. 249-266, 2004. [8] BENFIELD, W. A. andHRUDA, R. F., " Vibration analysis of structures

Architecture of the hydrophobic and hydrophilic layers as found from crystal structure analysis of N-benzyl-N,N-dimethylalkylammonium bromides.

PubMed

Hodorowicz, Maciej; Stadnicka, Katarzyna; Czapkiewicz, Jan

2005-10-01

The molecular and crystal structures of N-benzyl-N,N-dimethylalkylammonium bromides monohydrates with chain length n=8-10 have been determined. The crystals are isostructural with the N-benzyl-N,N-dimethyldodecylammonium bromide monohydrate. The structures consist of alternated hydrophobic and hydrophilic layers perpendicular to [001]. The attraction between N+ of the cation head-groups and Br- anions is achieved through weak C_H...Br interactions. The water molecules incorporated into ionic layers are donors for two O_H...Br hydrogen bonds and serve as the acceptors in two weak interactions of C_H...O type. The methylene chains, with the slightly curved general shape, have the extended all-trans conformation. The mutual packing of the chains in the hydrophobic layers is governed by weak C_H...pi interactions.

Molecular cloning and functional analysis of a UV-B photoreceptor gene, MdUVR8 (UV Resistance Locus 8), from apple.

PubMed

Zhao, Cheng; Mao, Ke; You, Chun-Xiang; Zhao, Xian-Yan; Wang, Shu-Hui; Li, Yuan-Yuan; Hao, Yu-Jin

2016-06-01

UVR8 (UV Resistance Locus 8) is an ultraviolet-B (UV-B; 280-315nm) light receptor that is involved in regulating many aspects of plant growth and development. UV-B irradiation can increase the development of flower and fruit coloration in many fruit trees, such as grape, pear and apple. Previous investigations of the structure and functions of UVR8 in plants have largely focused on Arabidopsis. Here, we isolated the UVR8 gene from apple (Malus domestica) and analyzed its function in transgenic Arabidopsis. Genomic and protein sequence analysis showed that MdUVR8 shares high similarity with the AtUVR8 protein from Arabidopsis, including the conserved seven-bladed β-propeller, the C27 region, the 3 "GWRHT" motifs and crucial amino-acid residues (14 Trps, 2 Args). A point mutation prediction and three-dimensional structural analysis of MdUVR8 indicated that it has a similar structure to AtUVR8 and that the crucial residues are also important in MdUVR8. In terms of transcript levels, MdUVR8 expression was up-regulated by UV-B light, which suggests that its expression follows a 24-h circadian rhythm. Using heterologous expression of MdUVR8 in both uvr8-1 mutant and wild-type (WT) Arabidopsis, we found that MdUVR8 regulates hypocotyl elongation and gene expression under UV-B light. These data provide functional evidence for a role of MdUVR8 in controlling photomorphogenesis under UV-B light and indicate that the function of UVR8 is conserved between Arabidopsis and apple. Furthermore, we examined the interaction between MdUVR8 and MdCOP1 (constitutive photomorphogenic1) using a yeast two-hybrid assay and a co-immunoprecipitation assay. This interaction provides a direction for investigating the regulatory mechanisms of the UV-B-light pathway in apple. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Two novel 2D lanthanide sulfate frameworks: Syntheses, structures, and luminescence properties

NASA Astrophysics Data System (ADS)

Li, Zhong-Yi; Zhang, Chi; Zhang, Fu-Li; Zhang, Fu-Qiang; Zhang, Xiang-Fei; Li, Su-Zhi; Cao, Guang-Xiu; Zhai, Bin

2016-03-01

Two novel lanthanide-sulfate compounds, [Ln2(SO4)3(H2O)8] (Ln = Tb (1) and Dy (2)), have been synthesized under hydrothermal reactions. X-ray crystal structure analyses reveal that 1 and 2 are isomorphous and crystallize in monoclinic C2/c pace group, showing a layered structure. The layers bear a rare quasi-honeycomb metal arrangement, which is fastened by μ3 = η1:η1:η1 and μ2 = η1:η1 sulfates. If assigning the μ3 = η1:η1:η1 sulfate as a 3-connected node and the Ln3+ ion as a 4-connected node, the network can be rationalized as a binodal (3,4)-connected V2O5 topology with a Schäfli symbol of (42·63·8) (42·6). In addition, the infrared, thermogravimetric analysis and luminescent properties were also studied. Complexes 1 and 2 exhibit outstanding thermal stability and characteristic terbium and dysprosium luminescence.

Differentiation-dependent expression of hypothetical proteins in the neuroblastoma cell line N1E-115.

PubMed

Oh, Ji-eun; Karlmark, Karlin Raja; Shin, Jooho; Hengstschläger, Markus; Lubec, Gert

2006-05-15

Several protein cascades, including signaling, cytoskeletal, chaperones, metabolic, and antioxidant proteins, have been shown to be involved in the process of neuronal differentiation (ND) of neuroblastoma cell lines. No systematic approach to detect hitherto unknown and unnamed proteins or structures that have been predicted upon nucleic acid sequences in ND has been published so far. We therefore decided to screen hypothetical protein (HP) expression by protein profiling. Two-dimensional gel electrophoresis with subsequent matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF/TOF) identification was used for expression analysis of undifferentiated and dimethylsulfoxide-induced neuronally differentiated N1E-115 cells. We unambiguously identified six HPs: Q8C520, Q99LF4, Q9CXS1, Q9DAF8, Q91WT0, and Q8C5G2. A prefoldin domain in Q91WT0, a t-SNARE domain in Q9CXS1, and a bromodomain were observed in Q8C5G2. For the three remaining proteins, no putative function using Pfam, BLOCKS, PROSITE, PRINTS, InterPro, Superfamily, CoPS, and ExPASy could be assigned. While two proteins were present in both cell lines, Q9CXS1 was switched off (i.e., undetectably low) in differentiated cells only, and Q9DAF8, Q91WT0, and Q8C5G2 were switched on in differentiated cells exclusively. Herein, using a proteomic approach suitable for screening and identification of HP, we present HP structures that have been only predicted so far based upon nucleic acid sequences. The four differentially regulated HPs may play a putative role in the process of ND. (c) 2006 Wiley-Liss, Inc.

Structural, spectral, DFT and biological studies on macrocyclic mononuclear ruthenium (II) complexes

NASA Astrophysics Data System (ADS)

Muthukkumar, M.; Kamal, C.; Venkatesh, G.; Kaya, C.; Kaya, S.; Enoch, Israel V. M. V.; Vennila, P.; Rajavel, R.

2017-11-01

Macrocyclic mononuclear ruthenium (II) complexes have been synthesized by condensation method [Ru (L1, L2, L3) Cl2] L1 = (C36 H31 N9), L2= (C42H36N8), L3= (C32H32 N8)]. These ruthenium complexes have been established by elemental analyses and spectroscopic techniques (Fourier transform infrared spectroscopy (FT-IR), 1H- nuclear magnetic resonance (NMR), 13C- NMR and Electrospray ionization mass spectrometry (ESI-MS)). The coordination mode of the ligand has been confirmed and the octahedral geometry around the ruthenium ion has been revealed. Binding affinity and binding mode of ruthenium (II) complexes with Bovine serum Albumin (BSA) have been characterized by Emission spectra analysis. UV-Visible and fluorescence spectroscopic techniques have also been utilized to examine the interaction between ligand and its complexes L1, L2, & L3 with BSA. Chemical parameters and molecular structure of Ru (II) complexes L1H, L2H, & L3H have been determined by DFT coupled with B3LYP/6-311G** functional in both the gaseous and aqueous phases.

Titan's Atmospheric Composition from Observations by the Cassini Infrared Spectrometer

NASA Technical Reports Server (NTRS)

Abbas, M. M.; LeClair, A.; Flasar, F. M.; Kunde, V. G.; Conrath, B. J.; Coustenis, A.; Jennings, D. J.; Nixon, C. A.; Brasunas, J.; Achterberg, R. K.

2006-01-01

The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft has been making observations during the fly-bys of Titan since the Saturn-Orbit-Insertion in July 2004. The observations provide infrared them1 emission spectra of Titan s atmosphere in three spectral channels covering the 10/cm to 1400/cm spectral region, with variable spectral resolutions of 0.53/cm and 2.8/cm. The uniquely observed spectra exhibit rotational and vibrational-rotational spectral lines of the molecular constituents of Titan s atmosphere that may be analyzed to retrieve information about the composition, thermal structure, and physical and dynamical processes in the remotely sensed atmosphere. We present an analysis of Titan's infrared spectra observed during July 2004 (TO), December 2004 (Tb) and February 2005 (T3), for retrieval of the stratospheric thermal structure, distribution of the hydrocarbons, nitriles, and oxygen bearing constituents, such as C2H2, C2H4, C2H6, C3H8, HCN, HC3N, CO, and CO2 . Preliminary results on the distribution and opacity of haze in Titan s atmosphere are discussed.

Microbolometer SU-8 photoresist microstructure with cytochrome c protein as a sensing pixel for microbolometer

NASA Astrophysics Data System (ADS)

Lai, Jian-Lun; Su, Guo-Dung J.

2012-08-01

There are two important parts in Microbolometer: the high TCR sensing material and low thermal conductance. The high TCR material cytochrome c protein is a good candidate for infrared detection. Our group already demonstrated cytochrome c thin film has high TCR on the top of SU8 surface that has been published in Proc. of SPIE (2011). Because the very low thermal conductivity of SU-8, we proposed a new concept of SU-8 photoresist thermal insulation desk structure, and used the exposure dose method to establish it. Although exposure dose method is very sensitive to exposure time and PEB time, we successfully investigated the right recipe to create new desk insulation structure which with different height. We also explored the relationship between mask II exposure time and desktop thickness, and how the post-exposure baking (PEB) time influenced our structure. Our SU-8 photoresist insulation structure fabrication process is much easier and cheaper than present SiNx fabrication process. The desk shape structure can have low thermal conductance of 6.681*10-6 W/K. The easy-made SU-8 microstructures and cytochrome c thin films that and can reduce the cost of IR microbolometer. We believe that it is possible to fabricate a new generation of microbolometer based on cytochrome c protein and SU-8 photoresist microstructures.

Pharmacokinetics, excretion of 8-cetylberberine and its main metabolites in rat urine.

PubMed

Hu, Yuli; Fan, Shoujun; Liao, Xiaobing; Chen, Chao; Su, Liang; Li, Xuegang

2017-01-05

Berberine (BBR) is a bioactive plant ingredient derived from the roots and bark of Berberis aristata and Coptis chinensis and has a wide variety of pharmacological effects. 8-cetylberberine (8-BBR-C16) is the berberine (BBR) derivative reconstructed from adding octadecyl at C-8 of BBR to enhance its activity. This study presents a reliable method for the determination of BBR and 8-BBR-C16 in rat plasma, urine and feces. BBR and 8-BBR-C16 were determined by HPLC-UV after liquid-liquid extraction for plasma samples, and solid-phase extraction for urinary and fecal samples. The method was linear over the concentration range of 10-300 ng·ml -1 for the plasma samples, 25-2000 ng·ml -1 for the urinary samples, and 100-2000 ng·g -1 for the fecal samples. Furthermore, a metabolic investigation on urine was performed by LC/MS/MS analysis to identify the structures of 8-BBR-C16 metabolites by full scan and product ion scan. Adult Sprague-Dawley rats were divided into two groups. In the control group, rats received 80 mg·kg -1 BBR, and in the drug-treated group, rats received 80 mg·kg -1 8-BBR-C16. The results indicate that there were significant differences in the pharmacokinetic parameters and in the accumulated excretion levels between the control group and the drug-treated group. The C max and AUC 0-t of 8-BBR-C16 were 2.8 and 12.9 times higher than those of BBR, and the relative bioavailability of BBR to 8-BBR-C16 was 7.7%. The total excretion amount through the urine and feces of 8-BBR-C16 was 76.9%, but that of BBR was only 20.5%. Additionally, 8-BBR-C16 was metabolized in rat urine with phase I demethylation and phase II glucuronidation or sulfation. Copyright © 2016 Elsevier B.V. All rights reserved.

Antifeedant effect of polygodial and drimenol derivatives against Spodoptera frugiperda and Epilachna paenulata and quantitative structure-activity analysis.

PubMed

Montenegro, Iván J; Del Corral, Soledad; Diaz Napal, Georgina N; Carpinella, María C; Mellado, Marco; Madrid, Alejandro M; Villena, Joan; Palacios, Sara M; Cuellar, Mauricio A

2018-07-01

The antifeedant activity of 18 sesquiterpenoids of the drimane family (polygodial, drimenol and derivatives) was investigated. Polygodial, drimanic and nordrimanic derivatives were found to exert antifeedant effects against two insect species, Spodoptera frugiperda and Epilachna paenulata, which are pests of agronomic interest, indicating that they have potential as biopesticide agents. Among the 18 compounds tested, the epoxynordrimane compound (11) and isonordrimenone (4) showed the highest activity [50% effective concentration (EC 50 ) = 23.28 and 25.63 nmol cm - 2 , respectively, against S. frugiperda, and 50.50 and 59.00 nmol/cm 2 , respectively, against E. paenulata]. The results suggest that drimanic compounds have potential as new agents against S. frugiperda and E. paenulata. A quantitative structure-activity relationship (QSAR) analysis of the whole series, supported by electronic studies, suggested that drimanic compounds have structural features necessary for increasing antifeedant activity, namely a C-9 carbonyl group and an epoxide at C-8 and C-9. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Using an SU-8 photoresist structure and cytochrome C thin film sensing material for a microbolometer.

PubMed

Lai, Jian-Lun; Liao, Chien-Jen; Su, Guo-Dung John

2012-11-27

There are two critical parameters for microbolometers: the temperature coefficient of resistance (TCR) of the sensing material, and the thermal conductance of the insulation structure. Cytochrome c protein, having a high TCR, is a good candidate for infrared detection. We can use SU-8 photoresist for the thermal insulation structure, given its low thermal conductance. In this study, we designed a platform structure based on a SU-8 photoresist. We fabricated an infrared sensing pixel and recorded a high TCR for this new structure. The SU-8 photoresist insulation structure was fabricated using the exposure dose method. We experimentally demonstrated high values of TCR from 22%/K to 25.7%/K, and the measured noise was 1.2 × 10(-8) V2/Hz at 60 Hz. When the bias current was 2 μA, the calculated voltage responsivity was 1.16 × 10(5) V/W. This study presents a new kind of microbolometer based on cytochrome c protein on top of an SU-8 photoresist platform that does not require expensive vacuum deposition equipment.

Using an SU-8 Photoresist Structure and Cytochrome C Thin Film Sensing Material for a Microbolometer

PubMed Central

Lai, Jian-Lun; Liao, Chien-Jen; Su, Guo-Dung John

2012-01-01

There are two critical parameters for microbolometers: the temperature coefficient of resistance (TCR) of the sensing material, and the thermal conductance of the insulation structure. Cytochrome c protein, having a high TCR, is a good candidate for infrared detection. We can use SU-8 photoresist for the thermal insulation structure, given its low thermal conductance. In this study, we designed a platform structure based on a SU-8 photoresist. We fabricated an infrared sensing pixel and recorded a high TCR for this new structure. The SU-8 photoresist insulation structure was fabricated using the exposure dose method. We experimentally demonstrated high values of TCR from 22%/K to 25.7%/K, and the measured noise was 1.2 × 10−8 V2/Hz at 60 Hz. When the bias current was 2 μA, the calculated voltage responsivity was 1.16 × 105 V/W. This study presents a new kind of microbolometer based on cytochrome c protein on top of an SU-8 photoresist platform that does not require expensive vacuum deposition equipment. PMID:23443384

Computer simulation of an Aircraft Seat and Occupant(s) in a Crash Environment - Program SOM-LA/SOM-TA (User Manual)

DTIC Science & Technology

1991-05-01

INFORMATION 8 2.7.1 Rigid Seat Option 8 2.7.2 Simplified Energy-Absorbing Seal Option 8 2.7.3 Finite Elemrent Structural Analysis 8 3.0 PROGRAM OUTPUT DATA 10...62000. 0,0 0.0 00035000 244130- STFEL 000330].0 7 .120E-4 29.086 163000. 6. CFb 180000. 0. 𔃻 00034010 174000. 81000, 0.0 0.0 00035010 8 0 0.4347 0.3028...0.0 IRoiational damping in neck. (Ub .’c). IIUCEIFjI.__Qti: Dimensions of seaL model as shown in Figure A-8. _45Y 0 V14567 ’TT2 l-8-7-T345367 0 1

Investigations on the crystal-structure and non-ambient behaviour of K2Ca2Si8O19 - a new potassium calcium silicate

NASA Astrophysics Data System (ADS)

Schmidmair, Daniela; Kahlenberg, Volker; Praxmarer, Alessandra; Perfler, Lukas; Mair, Philipp

2017-09-01

Within the context of a systematic re-investigation of phase relationships between compounds of the ternary system K2O-CaO-SiO2 a new potassium calcium silicate with the chemical formula K2Ca2Si8O19 was synthesized via solid state reactions as well as the flux method using KCl as a solvent. Its crystal structure was determined from single-crystal X-ray diffraction data by applying direct methods. The new compound crystallizes in the triclinic space group P 1 bar . Unit cell dimensions are a = 7.4231(7) Å, b = 10.7649(10) Å, c = 12.1252(10) Å, α = 70.193(8)°, β = 83.914(7)° and γ = 88.683(7)°. K2Ca2Si8O19 is built up of corner-connected, slightly distorted [SiO4]-tetrahedra forming double-sheets, which are linked by double-chains of edge-sharing [CaO6]-octahedra. Electroneutrality of the material is provided by additional potassium atoms that are located within the voids of the silicate layers and between adjacent [Ca2O6]-double-chains. Further characterization of the compound was performed by Raman spectroscopy and differential thermal analysis. The behaviour of K2Ca2Si8O19 under high-temperature and high-pressure was investigated by in-situ high-temperature powder X-ray diffraction up to a maximum temperature of 1125 °C and a piston cylinder experiment at 1.5 GPa and 1100 °C. Additionally an overview of known double-layer silicates is given as well as a comparison of K2Ca2Si8O19 to closely related structures.

Analysis of quaternary ammonium compounds in estuarine sediments by LC-ToF-MS: very high positive mass defects of alkylamine ions provide powerful diagnostic tools for identification and structural elucidation

PubMed Central

Li, Xiaolin; Brownawell, Bruce J.

2009-01-01

A sensitive and robust method of analysis for quaternary ammonium compounds (QACs) in marine sediments is presented. Methods for extraction, sample purification, and HPLC-Time-of-Flight-MS analysis were optimized, providing solutions to problems associated with analysis of QACs, such as dialkyldimethylammonium (DADMAC) and benzalkonium (BAC) compounds experienced previously. Recognized in this study are the exceptionally high positive mass defects characteristic of alkylammonium or protonated alkylamine ions. No alternative and chemically-viable elemental formulas exist within 25.2 mDa when the number of double bond equivalents is low, effectively allowing facile discrimination of this compound class in complex mixtures. Accurate mass measurements of diagnostic collision induced dissociation fragment ions and heavy isotope peaks were obtained and also seen to be uniquely heavy compared to other elemental formulae. In the case of BACs, the ability to resolve masses of alkylamine fragment ions is greater than it is for molecular ions, opening up a wide range of potential applications. The power of utilizing a combination of approaches is illustrated with the identification of non-targeted DADMAC C8:C8 and C8:C10, two widely used biocides previously unreported in environmental samples. Concentrations of QACs in sewage-impacted estuarine sediments (up to 74 μg/g) were higher than concentrations of other organic contaminants measured in the same or nearby samples, suggesting further study is needed. PMID:19739657

Summary of Aerodynamic Data for Structural Analysis of the B-36 Airplane, Revision 1,

DTIC Science & Technology

1950-06-01

b° 31 7c aw • 7.700 327d 0 % - 12.900 3 AA_ b• -- 5°O " -00% 6034 8b aw - 4.25 358C - 7.25𔃺, 36 6da • 12.550 M 7 ga 6 --10, a - -0.700 389b C11 :x...span loadi, aret 3.v"fl- cleatly accurate ani realistic, anl are not as mcnservative as a oarprison with prese-t test dita ww.d i-ldia-te. a, bAo.’ i

A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810

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

Zhang, Zilian; Cai, Ruanhong; Zhang, Wenhui

Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu 2+, Ni 2+, and Cr 6+ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS formore » heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu 2+ and Ni 2+ were 140.8-8.2 mg/g and 226.3-3.3 mg/g at pH 5.0; however, for Cr 6+ it was 215.2-5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni 2+ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.« less

A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810

DOE PAGES

Zhang, Zilian; Cai, Ruanhong; Zhang, Wenhui; ...

2017-06-12

Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu 2+, Ni 2+, and Cr 6+ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS formore » heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu 2+ and Ni 2+ were 140.8-8.2 mg/g and 226.3-3.3 mg/g at pH 5.0; however, for Cr 6+ it was 215.2-5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni 2+ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.« less

High-Resolution Infrared Studies of Perdeutero-Spiropentane, C 5D 8

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

Erickson, Blake A.; Ju, X.; Nibler, Joseph W.

Perdeutero-spiropentane (C 5D 8) has been synthesized and infrared and Raman spectra are reported for the first time. Wavenumber assignments are made for most of the fundamental vibrational modes. Gas phase infrared spectra were recorded at a resolution (0.002 cm -1) sufficient to resolve individual rovibrational lines and show evidence of strong Coriolis and/or Fermi resonance interactions for most bands. However a detailed rovibrational analysis of the fundamental v 15 (b 2) parallel band proved possible and a fit of more than 1600 lines yielded a band origin of 1053.84465(10) cm -1 and ground state constants (in units of cmmore » -1): B 0 = 0.1120700(9), D J = 1.51(3) x10 -8, D JK = 3.42(15) x10 -8. We note that the B 0 value is significantly less than a value of Ba = 0.1140 cm-1 calculated using structural parameters from an earlier electron diffraction (ED) study, whereas one expects B a to be lower than B 0 because of thermal averaging over higher vibrational levels. A similar discrepancy was noted in an earlier study of C 5H 8 [1]. The structural and spectroscopic results are in good accord with values computed at the anharmonic level using the B3LYP density functional method with a cc-pVTZ basis set.« less

Raman studied of undoped amorphous carbon thin film deposited by bias assisted-CVD

NASA Astrophysics Data System (ADS)

Ishak, A.; Fadzilah, A. N.; Dayana, K.; Saurdi, I.; Malek, M. F.; Nurbaya, Z.; Shafura, A. K.; Rusop, M.

2018-05-01

The undoped amorphous carbon thin film carbon was deposited at 200°C-350°C by bias assisted-CVD using palm oil as a precursor material. The effect of different substrate deposition temperatures on structural and electrical properties of undoped doped amorphous carbon film was discussed. The structural of undoped amorphous carbon films were correlated with Raman analysis through the evolution of D and G bands, Fourier spectra, and conductivity measurement. The spectral evolution observed showed the increase of upward shift of D and G peaks as substrate deposition temperatures increased. The spectral evolution observed at different substrate deposition temperatures show progressive formation of crystallites. It was predicted that small number of hydrogen is terminated with carbon at surface of thin film as shown by FTIR spectra since palm oil has high number of hydrogen (C67H127O8). These structural changes were further correlated with conductivity and the results obtained are discussed and compared. The conductivity is found in the range of 10-8 Scm-1. The increase of conductivity is correlated by the change of structural properties as correlated with characteristic parameters of Raman spectra including the position of G peak, full width at half maximum of G peak, and ID/IG and FTIR result.

[Diabetes care and incidence of severe hypoglycemia in nursing home facilities and nursing services: The Heidelberg Diabetes Study].

PubMed

Bahrmann, A; Wörz, E; Specht-Leible, N; Oster, P; Bahrmann, P

2015-04-01

The goal of this study was to perform a structured analysis of the treatment quality and acute complications of geriatric patients with diabetes mellitus (DM) cared for by nursing services and nursing home facilities. Secondly, structural problems and potentials for improvement in the care of multimorbid older people with DM treated by nursing homes and nursing services were analysed from the viewpoint of geriatric nurses, managers of nursing homes and general practitioners. In all, 77 older persons with DM from 13 nursing homes and 3 nursing services were included in the analysis (76.6% female, HbA1c 6.9 ± 1.4%, age 81.6 ± 9.9 years). Structural problems and potentials for improvement were collected from 95 geriatric nurses, 9 managers of nursing homes and 6 general practitioners using semistandardized questionnaires. Metabolic control was too strict in care-dependent older people with DM (mean HbA1c value: 6.9 ± 1.4 %; recommended by guidelines: 7-8%). The measurement of HbA1c was performed in 16 of 77 people (20.8%) within the last year despite a high visitation frequency of the general practitioners (12.7 ± 7.7 within the last 6 months). The incidence of severe hypoglycemia was 7.8%/patient/year. Regarding the management in case of diabetes-related acute complications 33 geriatric nurses (34.7%) stated not having any written standard (nursing home 39%, geriatric services 16.7%). Complex insulin therapies are still used in older people with DM with the consequence of a high incidence of severe hypoglycemia. Concrete management standards in the case of diabetes-related acute complications for geriatric nurses are lacking for more than one third of the nursing services.

Preparation, Characterization, and Structure of Two Layered Molybdenum(VI) Phosphates: KMo(H 2O)O 2PO 4 and NH 4Mo(H 2O)O 2PO 4

NASA Astrophysics Data System (ADS)

Millini, Roberto; Carati, Angela

1995-08-01

New layered Mo(VI) compounds, KMo(H 2O)O 2PO 4 (I) and NH 4Mo(H 2O)O 2PO 4 (II), were synthesized hydrothermally and their structures were determined from single-crystal X-ray analysis. Compounds (I) and (II) are isostructural and crystallize in the monoclinic P2 1/ n space group with a = 12.353(3), b = 8.623(2), c = 5.841(1) Å, β = 102.78(1)°, V = 606.8(2) Å 3, Z = 4, and R = 0.027 ( Rw = 0.030) for compound (I) and a = 12.435(3), b = 8.761(2), c = 6.015(1), β = 103.45(1)°, V = 637.3(2) Å 3, Z = 4, and R = 0.040 ( Rw = 0.041) for compound (II). The structure consists of layers built up of eight- and four-membered rings resulting from the alternation of corner-sharing [MoO 6] octahedra and [PO 4] tetrahedra. The layers stack along the (1¯01) direction by intercalating K and NH 4 ions.

Functional bacterial and archaeal community structures of major trophic groups in a full-scale anaerobic sludge digester.

PubMed

Ariesyady, Herto Dwi; Ito, Tsukasa; Okabe, Satoshi

2007-04-01

Functional Bacteria and Archaea community structures of a full-scale anaerobic sludge digester were investigated by using a full-cycle 16S rRNA approach followed by microautoradiography (MAR)-fluorescent in situ hybridization (FISH) technique and micromanipulation. FISH analysis with a comprehensive set of 16S and 23S rRNA-targeted oligonucleotide probes based on 16S rRNA clone libraries revealed that the Gram-positive bacteria represented by probe HGC69A-hybridized Actinobacteria (8.5+/-1.4% of total 4', 6-diamidino-2-phenylindole (DAPI)-stained cells) and probe LGC354-hybridized Firmicutes (3.8+/-0.8%) were the major phylogenetic bacterial phyla, followed by Bacteroidetes (4.0+/-1.2%) and Chloroflexi (3.7+/-0.8%). The probe MX825-hybridized Methanosaeta (7.6+/-0.8%) was the most abundant archaeal group, followed by Methanomicrobiales (2.8+/-0.6%) and Methanobacteriaceae (2.7+/-0.4%). The functional community structures (diversity and relative abundance) of major trophic groups were quantitatively analyzed by MAR-FISH. The results revealed that glucose-degrading microbial community had higher abundance (ca. 10.6+/-4.9% of total DAPI-stained cells) and diversity (at least seven phylogenetic groups) as compared with fatty acid-utilizing microbial communities, which were more specialized to a few phylogenetic groups. Despite the dominance of Betaproteobacteria, members of Chloroflexi, Smithella, Syntrophomonas and Methanosaeta groups dominated the [(14)C]glucose-, [(14)C]propionate-, [(14)C]butyrate- and [(14)C]acetate-utilizing microorganism community, and accounted for 27.7+/-4.3%, 29.6+/-7.0%, 34.5+/-7.6% and 18.2+/-9.5%, respectively. In spite of low abundance (ca. 1%), the hitherto unknown metabolic functions of Spirochaeta and candidate phylum of TM7 as well as Synergistes were found to be glucose and acetate utilization, respectively.

Copper(II) hexaaza macrocyclic binuclear complexes obtained from the reaction of their copper(I) derivates and molecular dioxygen.

PubMed

Costas, Miquel; Ribas, Xavi; Poater, Albert; López Valbuena, Josep Maria; Xifra, Raül; Company, Anna; Duran, Miquel; Solà, Miquel; Llobet, Antoni; Corbella, Montserrat; Usón, Miguel Angel; Mahía, José; Solans, Xavier; Shan, Xiaopeng; Benet-Buchholz, Jordi

2006-05-01

Density functional theory (DFT) calculations have been carried out for a series of Cu(I) complexes bearing N-hexadentate macrocyclic dinucleating ligands and for their corresponding peroxo species (1c-8c) generated by their interaction with molecular O2. For complexes 1c-7c, it has been found that the side-on peroxodicopper(II) is the favored structure with regard to the bis(mu-oxo)dicopper(III). For those complexes, the singlet state has also been shown to be more stable than the triplet state. In the case of 8c, the most favored structure is the trans-1,2-peroxodicopper(II) because of the para substitution and the steric encumbrance produced by the methylation of the N atoms. Cu(II) complexes 4e, 5e, and 8e have been obtained by O2 oxidation of their corresponding Cu(I) complexes and structurally and magnetically characterized. X-ray single-crystal structures for those complexes have been solved, and they show three completely different types of Cu(II)2 structures: (a) For 4e, the Cu(II) centers are bridged by a phenolate group and an external hydroxide ligand. The phenolate group is generated from the evolution of 4c via intramolecular arene hydroxylation. (b) For 5e, the two Cu(II) centers are bridged by two hydroxide ligands. (c) For the 8e case, the Cu(II) centers are ligated to terminally bound hydroxide ligands, rare because of its tendency to bridge. The evolution of complexes 1c-8c toward their oxidized species has also been rationalized by DFT calculations based mainly on their structure and electrophilicity. The structural diversity of the oxidized species is also responsible for a variety of magnetic behavior: (a) strong antiferromagnetic (AF) coupling with J = -482.0 cm(-1) (g = 2.30; rho = 0.032; R = 5.6 x 10(-3)) for 4e; (b) AF coupling with J = -286.3 cm(-1) (g = 2.07; rho = 0.064; R = 2.6 x 10(-3)) for 5e; (c) an uncoupled Cu(II)2 complex for 8e.

New vanadium tellurites: Syntheses, structures, optical properties of noncentrosymmetric VTeO{sub 4}(OH), centrosymmetric Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})

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

Liang, Ming-Li; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002; Marsh, Matthew

Two new vanadium tellurites, VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2), have been synthesized successfully with the use of hydrothermal reactions. The crystal structures of the two compounds were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the polar space group Pca2{sub 1} (No. 29) while compound 2 crystallizes in the centrosymmetric space group C2/c (No. 15). The topography of compound 1 reveals a two-dimensional, layered structure comprised of VO{sub 6} octahedral chains and TeO{sub 3}(OH) zig-zag chains. Compound 2, on the contrary, features a three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic framework withmore » Ba{sup 2+} ions filled into the 10-member ring helical tunnels. The [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic network is the first 3D vanadium tellurite framework to be discovered in the alkaline-earth vanadium tellurite system. Powder second harmonic generation (SHG) measurements indicate that compound 1 shows a weak SHG response of about 0.3×KDP (KH{sub 2}PO{sub 4}) under 1064 nm laser radiation. Infrared spectroscopy, elemental analysis, thermal analysis, and dipole moment calculations have also been carried out. - Graphical abstract: VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} (No. 29) while Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) crystallizes in the centrosymmetric space group C2/c (No. 15). - Highlights: • VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) have been synthesized successfully with the use of hydrothermal reactions. • VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} and displays a weak SHG response. • VTeO{sub 4}(OH) (1) represents only the fourth SHG-active material found in vanadium tellurite systems. • Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) exhibits a novel three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic framework.« less

Interfacial chemical and electronic structure of cobalt deposition on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT)

NASA Astrophysics Data System (ADS)

Zhu, Menglong; Lyu, Lu; Niu, Dongmei; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

2017-04-01

Interfacial chemical and electronic structure of Co deposition on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene(C8-BTBT) was investigated by ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS). Chemical reaction of cobalt with C8-BTBT at the interface is confirmed by a new component of S 2s peak which is electron-rich compared to the original one of C8-BTBT molecules. Intensity evolution of the core level in XPS indicates that the adsorption of Co atoms is mainly at the surface without deeper diffusion into C8-BTBT layer. Initial deposition of Co atoms downward shifts the core levels of C8-BTBT by electron transfer from isolated Co atoms or clusters to the C8-BTBT. Further deposition of Co upward shifts the core levels of C8-BTBT because of the neutralization of the thicker metal Co film. Our investigation suggests an inert buffer layer inserted to protect organic layer from reaction or decomposition and to lower the carrier barriers for both the electron and hole to improve the performance of Co/C8-BTBT-based OFETs.

Mechanism of pyranopterin ring formation in molybdenum cofactor biosynthesis

DOE PAGES

Hover, Bradley M.; Tonthat, Nam K.; Schumacher, Maria A.; ...

2015-05-04

The molybdenum cofactor (Moco) is essential for all kingdoms of life, plays central roles in various biological processes, and must be biosynthesized de novo. During Moco biosynthesis, the characteristic pyranopterin ring is constructed by a complex rearrangement of guanosine 5'-triphosphate (GTP) into cyclic pyranopterin (cPMP) through the action of two enzymes, MoaA and MoaC (molybdenum cofactor biosynthesis protein A and C, respectively). Conventionally, MoaA was considered to catalyze the majority of this transformation, with MoaC playing little or no role in the pyranopterin formation. Recently, this view was challenged by the isolation of 3',8-cyclo-7,8-dihydro-guanosine 5'-triphosphate (3',8-cH 2GTP) as the productmore » of in vitro MoaA reactions. To elucidate the mechanism of formation of Moco pyranopterin backbone, in this paper we performed biochemical characterization of 3',8-cH 2GTP and functional and X-ray crystallographic characterizations of MoaC. These studies revealed that 3',8-cH 2GTP is the only product of MoaA that can be converted to cPMP by MoaC. Our structural studies captured the specific binding of 3',8-cH 2GTP in the active site of MoaC. These observations provided strong evidence that the physiological function of MoaA is the conversion of GTP to 3',8-cH 2GTP (GTP 3',8-cyclase), and that of MoaC is to catalyze the rearrangement of 3',8-cH 2GTP into cPMP (cPMP synthase). Furthermore, our structure-guided studies suggest that MoaC catalysis involves the dynamic motions of enzyme active-site loops as a way to control the timing of interaction between the reaction intermediates and catalytically essential amino acid residues. In conclusion, these results reveal the previously unidentified mechanism behind Moco biosynthesis and provide mechanistic and structural insights into how enzymes catalyze complex rearrangement reactions.« less

Molecular Eigensolution Symmetry Analysis and Fine Structure

PubMed Central

Harter, William G.; Mitchell, Justin C.

2013-01-01

Spectra of high-symmetry molecules contain fine and superfine level cluster structure related to J-tunneling between hills and valleys on rovibronic energy surfaces (RES). Such graphic visualizations help disentangle multi-level dynamics, selection rules, and state mixing effects including widespread violation of nuclear spin symmetry species. A review of RES analysis compares it to that of potential energy surfaces (PES) used in Born–Oppenheimer approximations. Both take advantage of adiabatic coupling in order to visualize Hamiltonian eigensolutions. RES of symmetric and D2 asymmetric top rank-2-tensor Hamiltonians are compared with Oh spherical top rank-4-tensor fine-structure clusters of 6-fold and 8-fold tunneling multiplets. Then extreme 12-fold and 24-fold multiplets are analyzed by RES plots of higher rank tensor Hamiltonians. Such extreme clustering is rare in fundamental bands but prevalent in hot bands, and analysis of its superfine structure requires more efficient labeling and a more powerful group theory. This is introduced using elementary examples involving two groups of order-6 (C6 and D3~C3v), then applied to families of Oh clusters in SF6 spectra and to extreme clusters. PMID:23344041

Tuning of acyl-ACP thioesterase activity directed for tailored fatty acid synthesis.

PubMed

Feng, Yanbin; Zhang, Yunxiu; Wang, Yayue; Liu, Jiao; Liu, Yinghui; Cao, Xupeng; Xue, Song

2018-04-01

Medium-chain fatty acids have attracted significant attention as sources of biofuels in recent years. Acyl-ACP thioesterase, which is considered as the key enzyme to determine the carbon chain length, catalyzes the termination of de novo fatty acid synthesis. Although recombinant medium-chain acyl-ACP thioesterase (TE) affects the fatty acid profile in heterologous cells, tailoring of the fatty acid composition merely by engineering a specific TE is still intractable. In this study, the activity of a C8-C10-specific thioesterase FatB2 from Cuphea hookeriana on C10-ACP was quantified twice as high as that on C8-ACP based on a synthetic C8-C16 acyl-ACP pool in vitro. Whereas in vivo, it was demonstrated that ChFatB2 preferred to accumulate C8 fatty acids with 84.9% composition in the ChFatB2-engineered E. coli strain. To achieve C10 fatty acid production, ChFatB2 was rationally tuned based on structural investigation and enzymatic analysis. An I198E mutant was identified to redistribute the C8-ACP flow, resulting in C10 fatty acid being produced as the principal component at 57.6% of total fatty acids in vivo. It was demonstrated that the activity of TE relative to β-ketoacyl-ACP synthases (KAS) directly determined the fatty acid composition. Our results provide a prospective strategy in tailoring fatty acid synthesis by tuning of TE activities based on TE-ACP interaction.

Structure investigation of fluorinated aluminophosphate ULM-3 Al templated by 3-methylaminopropylamine

NASA Astrophysics Data System (ADS)

Zabukovec Logar, Natasa; Mali, Gregor; Rajic, Nevenka; Jevtic, Sanja; Rangus, Mojca; Golobic, Amalija; Kaucic, Venceslav

2010-05-01

A single-crystal X-ray diffraction analysis of an open-framework aluminophosphate ULM-3 Al prepared by 3-methylaminopropylamine (MAPA) as structure-directing agent revealed an orthorhombic Pcab symmetry ( a=9.9949(4) Å, b=15.8229(7) Å, c=18.1963(5) Å, R=0.0648, Z=8, unit cell formula [Al 24P 24O 96F 16·C 32H 112N 16]), which differs from the Pbc2 1 symmetry of the structural analogue prepared in the presence of 1,4-diaminobutane. The 27Al, 31P, 19F, 13C and 1H NMR investigations, which were performed to study in detail MAPA arrangement inside the framework as well as the interactions of MAPA with the aluminophosphate host, confirmed the crystal symmetry and the proposed hydrogen bonding scheme between the template and the framework.

Nanocrystalline ordered vanadium carbide: Superlattice and nanostructure

NASA Astrophysics Data System (ADS)

Kurlov, A. S.; Gusev, A. I.; Gerasimov, E. Yu.; Bobrikov, I. A.; Balagurov, A. M.; Rempel, A. A.

2016-02-01

The crystal structure, micro- and nanostructure of coarse- and nanocrystalline powders of ordered vanadium carbide V8C7 have been examined by X-ray and neutron diffraction and electron microscopy methods. The synthesized coarse-crystalline powder of ordered vanadium carbide has flower-like morphology. It was established that the real ordered phase has the composition V8C7-δ (δ ≅ 0.03) deviating from perfect stoichiometric composition V8C7. The vanadium atoms forming the octahedral environment □V6 of vacant sites in V8C7-δ are displaced towards the vacancy □. The presence of carbon onion-like structures was found in the vanadium carbide powders with a small content of free (uncombined) carbon. The nanopowders of V8C7-δ carbide with average particle size of 20-30 nm produced by high-energy milling of coarse-crystalline powder retain the crystal structure of the initial powder, but differ in the lattice deformation distortion anisotropy.

Common structural features of cholesterol binding sites in crystallized soluble proteins

PubMed Central

Bukiya, Anna N.; Dopico, Alejandro M.

2017-01-01

Cholesterol-protein interactions are essential for the architectural organization of cell membranes and for lipid metabolism. While cholesterol-sensing motifs in transmembrane proteins have been identified, little is known about cholesterol recognition by soluble proteins. We reviewed the structural characteristics of binding sites for cholesterol and cholesterol sulfate from crystallographic structures available in the Protein Data Bank. This analysis unveiled key features of cholesterol-binding sites that are present in either all or the majority of sites: i) the cholesterol molecule is generally positioned between protein domains that have an organized secondary structure; ii) the cholesterol hydroxyl/sulfo group is often partnered by Asn, Gln, and/or Tyr, while the hydrophobic part of cholesterol interacts with Leu, Ile, Val, and/or Phe; iii) cholesterol hydrogen-bonding partners are often found on α-helices, while amino acids that interact with cholesterol’s hydrophobic core have a slight preference for β-strands and secondary structure-lacking protein areas; iv) the steroid’s C21 and C26 constitute the “hot spots” most often seen for steroid-protein hydrophobic interactions; v) common “cold spots” are C8–C10, C13, and C17, at which contacts with the proteins were not detected. Several common features we identified for soluble protein-steroid interaction appear evolutionarily conserved. PMID:28420706

The crystal structure and morphology of NiO-YSZ composite that prepared from local zircon concentrate of Bangka Island

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

Rahmawati, F., E-mail: fitria@mipa.uns.ac.id; Apriyani, K.; Heraldy, E.

2016-03-29

In order to increase the economic value of local zircon concentrate from Bangka Island, NiO-YSZ was synthesized from Zirconia, ZrO{sub 2} that was prepared from local zircon concentrate. The NiO-YSZ composite was synthesized by solid state reaction method. XRD analysis equipped with Le Bail refinement was carried out to analyze the crystal structure and cell parameters of the prepared materials. The result showed that zirconia was crystallized in tetragonal structure with a space group of P42/NMC. Yttria-Stabilized-Zirconia (YSZ) was prepared by doping 8% mol yttrium oxide into zirconia and then sintered at 1250°C for 3 hours. Doping of 8% molmore » Yttria allowed phase transformation of zirconia from tetragonal into the cubic structure. Meanwhile, the composite of NiO-YSZ consists of two crystalline phases, i.e. the NiO with cubic structure and the YSZ with cubic structure. SEM analysis of the prepared materials shows that the addition of NiO into YSZ allows the morphology to become more roughness with larger grain size.« less

Crystal structures and theoretical studies of polyphosphate LiZnP3O9 for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Xie, Zhiqing; Su, Xin; Ding, Hanqin; Li, Hongyi

2018-06-01

Nonlinear optical materials have attracted worldwide attention owing to their wide range of applications, specially in the laser field. Phosphates with noncentrosymmetric structures are potential candidates for novel ultraviolet (UV)-NLO materials, because they usually display short UV cut-off edges. In this work, a polyphosphate, the LiZnP3O9 polyphosphate crystals were grown through spontaneous crystallization from high-temperature melts. It crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 8.330(3) Å, b = 8.520(3) Å, c = 8.635(3) Å, and Z = 4. In the structure, all the P atoms are coordinated by four oxygen atoms forming the [PO4] tetrahedra and further connected to generate a zig-zag [PO3]∞ anionic framework. Thermal analysis, IR spectroscopy, UV-vis-NIR diffuse reflectance spectrum and powder second harmonic generation measurements are performed. In addition, the first-principles calculation was employed for better understanding the structure-property relationships of LiZnP3O9.

High pressure structure studies of 6H-SrIrO3 and the octahedral tilting in 3C-SrIrO3 towards a post-perovskite

NASA Astrophysics Data System (ADS)

Kronbo, Camilla H.; Nielsen, Morten B.; Kevy, Simone M.; Parisiades, Paraskevas; Bremholm, Martin

2016-06-01

The high pressure behaviors of the two perovskite structures (hexagonal 6H-SrIrO3 and orthorhombic 3C-SrIrO3) have been studied in diamond anvil cells to 43 and 60 GPa, respectively, using synchrotron powder X-ray diffraction. 6H-SrIrO3 was first synthesized at ambient pressure and subsequently transformed into 3C-SrIrO3 in a large volume press at 8.8 GPa and 1000 °C. Both polymorphs were found to retain the initial symmetry up to the highest pressures measured, but in the case of 6H-SrIrO3, two anomalies were identified: a change in the axial compressibilities at 24 GPa and a change in both the axial and volume compressibilities at 32 GPa. Fitting a 3rd order Birch-Murnaghan equation of state to the obtained P-V data yielded bulk moduli of K0=151.5(12) GPa (fitted range 0

The immune adjuvant response of polysaccharides from Atractylodis macrocephalae Koidz in chickens vaccinated against Newcastle disease (ND).

PubMed

Zhao, Xiaona; Sun, Wenjing; Zhang, Shijie; Meng, Guangju; Qi, Chunhua; Fan, Wentao; Wang, Yuge; Liu, Jianzhu

2016-05-05

Build on our previous research, polysaccharides from the rhizome of Atractylodis macrocephalae Koidz (RAMPS), RAMPStp and RAMPS60c were prepared and the structural characterization and immune response of ND vaccine in chicken were investigated. Immune organ index, Lymphocyte proliferation, antibody titers, cell cycle distribution, and percentages of CD4(+) and CD8(+) cells were determined. GPC analysis showed that the Mn of RAMPS with two peaks were 1.29×10(5) and 1.74×10(3), respectively. GC-MS analysis revealed that RAMPS was composed of glucose, mannose, arabinose, galactose, xylose, d-Ribose and rhamnose, with mass percentages of 66.39%, 21.24%, 5.64%, 2.65%, 2.30%, 1.15% and 0.64%, respectively. NMR spectroscopic analysis demonstrated that a preliminary structure of RAMPS was proposed as 1,3-linked β-d-Galp and 1,6-linked β-d-Galpresidues. In vivo test showed that RAMPStp and RAMPS60c could promote peripheral lymphocytes proliferation and entering into S and G2/M phases, enhance serum HI antibody titer and effectively improve the percentages of CD4(+) and CD8(+) T cells in chickens vaccinated with ND vaccine at most time points. The actions of RAMPStp and RAMPS60c were stronger than that of Lev, and RAMPStp presented the best efficacy. These results indicated that RAMPStp and RAMPS60c characterize of the immune-enhancing activity and RAMPStp possessed the strongest activity. It would be anticipated as a component of new-type immunopotentiator. Copyright © 2016 Elsevier Ltd. All rights reserved.

Physical properties of monolithic U8 wt.%-Mo

NASA Astrophysics Data System (ADS)

Hengstler, R. M.; Beck, L.; Breitkreutz, H.; Jarousse, C.; Jungwirth, R.; Petry, W.; Schmid, W.; Schneider, J.; Wieschalla, N.

2010-07-01

As a possible high density fuel for research reactors, monolithic U8 wt.%-Mo ("U8Mo") was examined with regard to its structural, thermal and electric properties. X-ray diffraction by the Bragg-Brentano method was used to reveal the tetragonal lattice structure of rolled U8Mo. The specific heat capacity of cast U8Mo was determined by differential scanning calorimetry, its thermal diffusivity was measured by the laser flash method and its mass density by Archimedes' principle. From these results, the thermal conductivity of U8Mo in the temperature range from 40 °C to 250 °C was calculated; in the measured temperature range, it is in good accordance with literature data for UMo with 8 and 9 wt.% Mo, is higher than for 10 wt.% Mo and lower than for 5 wt.% Mo. The electric conductivity of rolled and cast U8Mo was measured by a four-wire method and the electron based part of the thermal conductivity calculated by the Wiedemann-Frantz law. Rolled and cast U8Mo was irradiated at about 150 °C with 80 MeV 127I ions to receive the same iodine ion density in the damage peak region as the fission product density in the fuel of a typical high flux reactor after the targeted nuclear burn-up. XRD analysis of irradiated U8Mo showed a change of the lattice parameters as well as the creation of UO 2 in the superficial sample regions; however, a phase change by irradiation was not observed. The determination of the electron based part of the thermal conductivity of the irradiated samples failed due to high measurement errors which are caused by the low thickness of the damage region in the ion irradiated samples.

Molecular structure of Ti8C12 and related complexes.

PubMed Central

Pauling, L

1992-01-01

Application of valence-bond theory leads to the assignment to the molecule Ti8C12 of a cubic structure, point group Ohm3m, with 8 Ti at the cube corners, +/-(x x x, x, x x [symbol, see text]) where x = 1.78 A, and with 12 C in pairs in the cube faces, +/-(0 y z, [symbol, see text], 0, y z [symbol, see text]) where y = 1.78 A and z = 0.71 A. The Ti-C and C-C bonds have bond number 4/3, corresponding to resonance of single and double bonds in 2:1 ratio. PMID:11607323

Structural and Functional Analysis of the Signal-Transducing Linker in the pH-Responsive One-Component System CadC of Escherichia coli.

PubMed

Buchner, Sophie; Schlundt, Andreas; Lassak, Jürgen; Sattler, Michael; Jung, Kirsten

2015-07-31

The pH-responsive one-component signaling system CadC in Escherichia coli belongs to the family of ToxR-like proteins, whose members share a conserved modular structure, with an N-terminal cytoplasmic winged helix-turn-helix DNA-binding domain being followed by a single transmembrane helix and a C-terminal periplasmic pH-sensing domain. In E. coli CadC, a cytoplasmic linker comprising approximately 50 amino acids is essential for transmission of the signal from the sensor to the DNA-binding domain. However, the mechanism of transduction is poorly understood. Using NMR spectroscopy, we demonstrate here that the linker region is intrinsically disordered in solution. Furthermore, mutational analyses showed that it tolerates a range of amino acid substitutions (altering polarity, rigidity and α-helix-forming propensity), is robust to extension but is sensitive to truncation. Indeed, truncations either reversed the expression profile of the target operon cadBA or decoupled expression from external pH altogether. CadC dimerizes via its periplasmic domain, but light-scattering analysis provided no evidence for dimerization of the isolated DNA-binding domain, with or without the linker region. However, bacterial two-hybrid analysis revealed that CadC forms stable dimers in a stimulus- and linker-dependent manner, interacting only at pH<6.8. Strikingly, a variant with inversed cadBA expression profile, which lacks most of the linker, dimerizes preferentially at higher pH. Thus, we propose that the disordered CadC linker is required for transducing the pH-dependent response of the periplasmic sensor into a structural rearrangement that facilitates dimerization of the cytoplasmic CadC DNA-binding domain. Copyright © 2015 Elsevier Ltd. All rights reserved.

HRTEM and chemical study of an ion-irradiated chromium/zircaloy-4 interface

NASA Astrophysics Data System (ADS)

Wu, A.; Ribis, J.; Brachet, J.-C.; Clouet, E.; Leprêtre, F.; Bordas, E.; Arnal, B.

2018-06-01

Chromium-coated zirconium alloys are being studied as Enhanced Accident Tolerant Fuel Cladding for Light Water Reactors (LWRs). Those materials are especially studied to improve the oxidation resistance of LWRs current fuel claddings in nominal and at High Temperature (HT) for hypothetical accidental conditions such as LOss of Coolant Accident. Beyond their HT behavior, it is essential to assess the materials behavior under irradiation. A first generation chromium/Zircaloy-4 interface was thus irradiated with 20 MeV Kr8+ ions at 400 °C up to 10 dpa. High-Resolution Transmission Electron Microscopy and chemical analysis (EDS) were conducted at the Cr/Zr interface. The atomic structure of the interface reveals the presence of Zr(Fe, Cr)2 Laves phase, displaying both C14 and C15 structure. After irradiation, only the C14 structure was observed and atomic row matching was preserved across the different interfaces, thus ensuring a good adhesion of the coating after irradiation.

Synthesis, structures and properties of the new lithium cobalt(II) phosphate Li{sub 4}Co(PO{sub 4}){sub 2}

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

Glaum, R., E-mail: rglaum@uni-bonn.de; Gerber, K.; Schulz-Dobrick, M.

2012-04-15

{alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} has been synthesized and crystallized by solid-state reactions. The new phosphate crystallizes in the monoclinic system (P2{sub 1}/a, Z=4, a=8.117(3) Angstrom-Sign , b=10.303(8) Angstrom-Sign , c=8.118(8) Angstrom-Sign , {beta}=104.36(8) Angstrom-Sign ) and is isotypic to {alpha}-Li{sub 4}Zn(PO{sub 4}){sub 2}. The structure of {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} has been determined from single-crystal X-ray diffraction data {l_brace}R{sub 1}=0.040, wR{sub 2}=0.135, 2278 unique reflections with F{sub o}>4{sigma}(F{sub o}){r_brace}. The crystal structure, which might be regarded as a superstructure of the wurtzite structure type, is build of layers of regular CoO{sub 4}, PO{sub 4} and Li1O{sub 4} tetrahedra. Lithium atomsmore » Li2, Li3 and Li4 are located between these layers. Thermal investigations by in-situ XRPD, DTA/TG and quenching experiments suggest decomposition followed by formation and phase transformation of Li{sub 4}Co(PO{sub 4}){sub 2}: {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} Long-Rightwards-Double-Arrow {sup 442 Degree-Sign C}{beta}-Li{sub 3}PO{sub 4}+LiCoPO{sub 4} Rightwards-Harpoon-Over-Leftwards-Harpoon {sup 773 Degree-Sign C}{beta}-Li{sub 4}Co(PO{sub 4}){sub 2} Long-Rightwards-Double-Arrow {sup quenchingto25 Degree-Sign C}{alpha}-Li{sub 4} Co(PO{sub 4}){sub 2} According to HT-XRPD at {theta}=850 Degree-Sign C{beta}-Li{sub 4}Co(PO{sub 4}){sub 2} (Pnma, Z=2, 10.3341(8) A, b=6.5829(5) A, c=5.0428(3) Angstrom-Sign ) is isostructural to {gamma}-Li{sub 3}PO{sub 4}. The powder reflectance spectrum of {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} shows the typical absorption bands for the tetrahedral chromophore [Co{sup II}O{sub 4}]. - Graphical abstract: The complex formation and decomposition behavior of Li{sub 4}Co(PO{sub 4}){sub 2} with temperature has been elucidated. The crystal structure of its {alpha}-phase was determined from single crystal data, HT-XRPD allowed derivation of a structure model for the {beta}-phase. Both modifications belong to the Li{sub 3}PO{sub 4} structure family. Highlights: Black-Right-Pointing-Pointer Li{sub 4}Co(PO{sub 4}){sub 2} exhibits complex thermal behavior. Black-Right-Pointing-Pointer The new phosphate belongs to the Li{sub 3}PO{sub 4} structure family. Black-Right-Pointing-Pointer A single-crystal structure analysis is provided for the metastable {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2}. Black-Right-Pointing-Pointer From HT-XRPD data a cation distribution model is developed for {beta}-Li{sub 4}Co(PO{sub 4}){sub 2}. Black-Right-Pointing-Pointer No electrochemical delithiation is observed up to 5 V.« less

Metal-organic frameworks assembled from lanthanide and 2,5-pyridinedicaboxylate with cubane-like [Ln4(OH)4] building units

NASA Astrophysics Data System (ADS)

Abdelbaky, Mohammed S. M.; Amghouz, Zakariae; Fernández-Zapico, Eva; García-Granda, Santiago; García, José R.

2015-09-01

Lanthanide-organic frameworks based on 2,5-pyridinedicaboxylate (25p) ligand, formulated as [Yb4(OH)4(25p)4(H2O)3]·H2O (25pYb), [Y4(OH)4(25p)4(H2O)3]·H2O (25pY-1) and [Y6(OH)8(25p)5(H2O)2] (25pY-2), have been obtained as single phases under hydrothermal conditions. 25pYb and 25pY-1 are isostructural, and crystallize in the triclinic space group, P-1, with a=8.6075(5) Å, b=14.8478(7) Å, c=15.9164(9) Å, α=86.277(4)°, β=80.196(5)°, γ=81.785(4)°, and a=8.7166(6) Å, b=14.966(1) Å, c=15.966(1) Å, α=86.260(6)°, β=80.036(6)°, γ=81.599(6)°, respectively. 25pY-2 crystallizes in the monoclinic space group, P21/c, with a=24.9117(17) Å, b=13.7340(8) Å, c=14.3385(10) Å, β=100.551(7)°. 25pYb and 25pY-2 have been structurally characterized by single-crystal X-ray diffraction. The 25pYb structure is based on tetranuclear cubane-like [Yb4(OH)4]8+ clusters, which are interconnected to eight neighbouring clusters through teen surrounding 25p ligands leading to neutral 3D framework, while the structure of 25pY-2 is based on two independent cuban-like [Y4(OH)4]8+ clusters, which are joined together through Y1 cation leading to the formation of hexanuclear [Y6(OH)8]10+ clusters, which in turn are joined via Y2 cation resulting in infinite inorganic chain extending along c-axis, and each chain is interconnected to six adjacent chains through 25p ligands leading finally to 3D framework. The luminescence properties of Eu3+ and Tb3+ doped 25pY-1 and 25pY-2 compounds have also been investigated. All materials has been characterized by powder X-ray diffraction, thermal analyses (TG-SDTA-MS), FTIR spectroscopy, C-H-N elemental analysis, scanning electron microscopy (SEM-EDX), and powder X-ray thermodiffraction.

N-2-Hydroxy-4-methoxyacetophenone- N'-4-nitrobenzoyl hydrazine: Synthesis and structural characterization

NASA Astrophysics Data System (ADS)

Bessy Raj, B. N.; Kurup, M. R. Prathapachandra

2007-04-01

A new aroyl hydrazone, N-2-hydroxy-4-methoxyacetophenone- N'-4-nitrobenzoyl hydrazine was prepared by the condensation reaction of 2-hydroxy-4-methoxyacetophenone and 4-nitrobenzoyl hydrazine. Characterization of the compound was done by elemental analysis and electronic, infrared and NMR spectral analyses. The complete structural assignment of the compound was done by NMR studies by using COSY homonuclear and HSQC heteronuclear techniques. The crystal and molecular structure was determined by single crystal X-ray diffraction studies: crystallized in the monoclinic system, space group P2 1/ n, Z = 4, a = 7.3343(9) Å, b = 20.3517(9) Å, c = 10.1375(5) Å, α = 90.00°, β = 95.735(7)° and γ = 90.00°. From the crystal structure, it is concluded that the compound exists as the keto isomer in the solid state. There is a completely extended conformation in the central part of the molecule C5 sbnd C8 dbnd N1 sbnd N2 sbnd C10 dbnd O2 with an E configuration at the double bond of the hydrazinic bridge.

Hydrothermal synthesis and characterization of a two-dimensional piperazinium cobalt–zinc phosphate via a metastable one-dimensional phase

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

Torre-Fernández, Laura; Khainakova, Olena A.; Espina, Aránzazu

2015-05-15

A two-dimensional piperazinium cobalt–zinc phosphate, formulated as (C{sub 4}N{sub 2}H{sub 12}){sub 1.5}(Co{sub 0.6}Zn{sub 0.4}){sub 2}(HPO{sub 4}){sub 2}(PO{sub 4})·H{sub 2}O (2D), was synthesized under hydrothermal conditions. The crystal structure was determined using single-crystal X-ray diffraction data (monoclinic P2{sub 1}/c, a=8.1165(3) Å, b=26.2301(10) Å, c=8.3595(4) Å, and β=110.930(5)°) and the hydrogen atom positions were optimized by DFT calculations. A single-crystal corresponding to one-dimensional metastable phase, (C{sub 4}N{sub 2}H{sub 12})Co{sub 0.3}Zn{sub 0.7}(HPO{sub 4}){sub 2}·H{sub 2}O (1D), was also isolated and the crystal structure was determined (monoclinic P2{sub 1}/c, a=8.9120(6) Å, b=14.0290(1) Å, c=12.2494(5) Å, and β=130.884(6)°). The bulk was characterized by chemical (C–H–N)more » analysis, powder X-ray diffraction (PXRD), powder X-ray thermodiffractometry (HT-XRD), transmission electron microscopy (STEM(DF)-EDX and EFTEM), and thermal analysis (TG/SDTA-MS), including activation energy data of its thermal decomposition. The magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. - Graphical abstract: Hydrothermal synthesis and structural characterization of a two-dimensional piperazinium cobalt–zinc phosphate, (C{sub 4}N{sub 2}H{sub 12}){sub 1.5}(Co{sub 0.6}Zn{sub 0.4}){sub 2}(HPO{sub 4}){sub 2}(PO{sub 4})·H{sub 2}O (2D), have been reported. The crystal structure of a one-dimensional piperazinium cobalt–zinc phosphate, (C{sub 4}N{sub 2}H{sub 12})Co{sub 0.3}Zn{sub 0.7}(HPO{sub 4}){sub 2}·H{sub 2}O (1D) a metastable phase during the hydrothermal synthesis, was also determined. The thermal behavior of 2D compound is strongly dependent on the selected heating rate and the magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. - Highlights: • A 2D piperazinium cobalt–zinc phosphate has been synthesized and characterized. • Crystal structure of 1D metastable phase was also determined. • Thermal behavior of 2D compound is strongly dependent on the selected heating rate. • Magnetic measurements show no magnetic ordering down to 4 K.« less

Sodium 4-phenylbutyrate ameliorates the effects of cataract-causing mutant gammaD-crystallin in cultured cells.

PubMed

Gong, Bo; Zhang, Li-Yun; Lam, Dennis Shun-Chiu; Pang, Chi-Pui; Yam, Gary Hin-Fai

2010-06-04

gammaD-Crystallin (CRYGD) is a major structural lens crystallin and its mutations result in congenital cataract formation. In this study, we attempted to correct the altered protein features of G165fsX8 CRYGD protein with small chemical molecules. Recombinant FLAG-tagged mutants (R15C, R15S, P24T, R61C, and G165fsX8) of CRYGD were expressed in COS-7 cells and treated with small chemical molecules with reported protein chaperoning properties (sodium 4-phenylbutyrate [4-PBA], trimethylamine N-oxide [TMAO], and glycerol and DMSO [DMSO]). Protein solubility in 0.5% Triton X-100 and subcellular distribution was examined by western blotting and immunofluorescence, respectively. Apoptosis was assayed as the percentage of fragmented nuclei in transfected cells. Expression of heat-shock proteins (Hsp70 and Hsp90) was examined by reverse transcription-polymerase chain reaction analysis. Unlike WT and most mutants (R15C, R15S, P24T, and R61C) of CRYGD, G165fsX8 CRYGD was significantly insoluble in 0.5% Triton X-100. This insolubility was alleviated by dose-dependent 4-PBA treatment. The treatment relieved the mislocalization of G165fsX8 CRYGD from the nuclear envelope. Also, 4-PBA treatment reduced cell apoptosis and caused an upregulation of Hsp70. 4-PBA treatment reduced the defective phenotype of mutant G165fsX8 CRYGD and rescued the affected cells from apoptosis. This could be a potential treatment for lens structural protein and prevent lens opacity in cataract formation.

Intramolecular B-B Linkage Between Polyhedral Cages in a Commo-Metallacarborane. Synthesis and Structure of a Fluxional Metal-Boron Cluster, (n(5)-C5(CH3)5)2Co3(CH3)4C4B8H7.

DTIC Science & Technology

1980-11-01

FINSTER , E SINN, R N GRIMES N0001475--0305 UNCLASSIFIED TR-35 NL’ minimnmlhnnnhu ,IIIIIIIIIIIIIl hEIIIIIIIIEIII EEEEEEEEEEEL 1.8 MICROCOPY’ RESOLUTION...David C./ Finster Ekk/inn Russell . Grimes Department of Chemistry ",00t University ofLyirginla ’ Charlottesville, Va. 22901 Prepared for Publication In...a Commo-Metallacarborane. Synthesis and Structure of a Fluxi:. Metal-Boron Cluster, [n5C 5 (CCB3)512HCo3(C13)4C4B8H7 David C. Finster , Ekk Sinn, and

Development and validation of the Australian Aboriginal racial identity and self-esteem survey for 8-12 year old children (IRISE_C).

PubMed

Kickett-Tucker, C S; Christensen, D; Lawrence, D; Zubrick, S R; Johnson, D J; Stanley, F

2015-10-24

In Australia, there is little empirical research of the racial identity of Indigenous children and youth as the majority of the current literature focuses on adults. Furthermore, there are no instruments developed with cultural appropriateness when exploring the identity and self-esteem of the Australian Aboriginal population, especially children. The IRISE_C (Racial Identity and Self-Esteem of children) inventory was developed to explore the elements of racial identity and self-esteem of urban, rural and regional Aboriginal children. This paper describes the development and validation of the IRISE_C instrument with over 250 Aboriginal children aged 8 to 12 years. A pilot of the IRISE C instrument was combined with individual interviews and was undertaken with 35 urban Aboriginal children aged 8-12 years. An exploratory factor analysis was performed to refine the survey and reduce redundant items in readiness for the main study. In the main study, the IRISE C was employed to 229 Aboriginal children aged 6-13 years across three sites (rural, regional and urban) in Western Australia. An exploratory factor analysis using Principal axis factoring was used to assess the fit of items and survey structure. A confirmatory factor analysis was then employed using LISREL (diagonally weighted least squares) to assess factor structures across domains. Internal consistency and reliability of subscales were assessed using Cronbach's co-efficient alpha. The pilot testing identified two key concepts - children's knowledge of issues related to their racial identity, and the importance, or salience, that they attach to these issues. In the main study, factor analyses showed two clear factors relating to: Aboriginal culture and traditions; and a sense of belonging to an Aboriginal community. Principal Axis Factoring of the Knowledge items supported a 2-factor solution, which explained 38.7% of variance. Factor One (Aboriginal culture) had a Cronbach's alpha of 0.835; Factor 2 (racial identity) had a Cronbach's alpha of 0.800, thus demonstrating high internal reliability of the scales. The IRISE_C has been shown to be a valid instrument useful of exploring the development of racial identity of Australian Aboriginal children across the 8-12 year old age range and across urban, rural and regional geographical locations.

High-pressure behavior of cuprospinel CuFe 2O 4: Influence of the Jahn-Teller effect on the spinel structure

DOE PAGES

Kyono, Atsushi; Gramsch, Stephen A.; Nakamoto, Yuki; ...

2015-08-14

The Jahn-Teller-effect at Cu 2+ in cuprospinel CuFe 2O 4 was investigated using high-pressure, single crystal synchrotron x-ray diffraction (XRD) techniques at beamline BL10A at the Photon Factory, KEK, Japan. Six data sets were collected in the pressure range from ambient to 5.9 GPa at room temperature. Structural refinements based on the data were performed at 0.0, 1.8, 2.7, and 4.6 GPa. The unit cell volume of cuprospinel decreases continuously from 590.8 (6) Å 3 to 579.5 (8) Å 3 up to 3.8 GPa. Leastsquares fitting to a third-order Birch-Murnaghan equation of state yields zero-pressure volume V 0 = 590.7more » (1) Å 3 and bulk modulus K 0 = 188.1 (4.4) GPa with K’ fixed at 4.0. The crystal chemical composition determined by electron-probe analysis and x-ray site-occupancy refinement is represented as [Cu 0.526Fe 0.474] [6][Cu 0.074Fe 1.926]O 4. Most of the Cu 2+ are preferentially distributed onto the tetrahedral (T) site of the spinel structure. At 4.6 GPa, a cubic-tetragonal phase transition is indicated by a splitting of the a axis of the cubic structure into a smaller a axis and a longer c axis, with unit cell parameters a = 5.882 (1) Å and c = 8.337 (1) Å. The tetragonal crystal structure with space group I4 1/amd was refined to R1 = 0.0182 and wR2 = 0.0134 using observed 35 x-ray reflections. At the T site, the tetrahedral O-T-O bond angles along the c-axis direction of the unit cell decreases slightly from 109.47 ° to 108.7 (4) °, which generates a stretched tetrahedral geometry along the c-axis. The cubic-totetragonal transition induced by the Jahn-Teller effect at Cu 2+ is attributable to the angular distortion at the tetrahedral site. At the octahedral (M) site, on the other hand, the two M-O bonds parallel to the caxis are shortened with respect to the four M-O bonds parallel to the ab-plane, which are lengthened as a result of the phase transition, leading to a compressed octahedral geometry along the c-axis. With the competing distortions between the stretched tetrahedron and the compressed octahedron along the c-axis, the a unit cell parameter is shortened with respect to the c unit cell parameter, giving a c/a ratio slightly greater than unity as referred to cubic lattice (c/a = 1.002). The c/a value increases to 1.007 with pressure, suggesting a further evolution of the stretched tetrahedron and the compressed octahedron. The variation of c/a ratio of the cuprospinel is similar to that observed in the tetragonally distorted cuprospinel with Cu 2+ fully occupying the octahedral site of the structure.« less

Fast dynamic electron transfer along infinite anion-cation chains in technetium and rhenium acido clusters

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

Antipov, B.G.; Kryuchkov, S.V.; Grigor`ev, M.S.

1995-09-01

New technetium and rhenium compounds with ferricenium cations - [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}I{sub 14}], [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}Cl{sub 14}], [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 2}[Tc{sub 8}Br{sub 14}], and [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 2}[Re{sub 2}Br{sub 8}] - are synthesized and identified. The compounds are characterized by the methods of static magnetic susceptibility and differential scanning calorimetry; solid-state conductivity measurements; and IR, EPR, {sup 57}Fe Moessbauer, and X-ray photoelectron spectroscopic data. These data are compared with the physicochemical characteristics of ferricenium pertechnetate and hexachlorotechnetate, as well as of a number of reference technetium and rhenium compounds containing the samemore » anions but different cations. The structure of [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}I{sub 14}] is determined by X-ray diffraction analysis of a single crystal [space group P6/m, a = 15.34(2), c = 12.70(1) {angstrom}]. The structures of the remaining compounds were confirmed by comparing their spectroscopic properties with corresponding properties of compounds with known composition and structure. None of the compounds with ferricenium cations exhibit covalent or other localized bonds between anions and cations. However, the physicochemical properties of these compounds indicate the occurrence of a fast dynamic electron transfer along infinite anion-cation chains. Compounds [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}Cl{sub 14}] and [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 2}[Tc{sub 8}Br{sub 14}] were found to exhibit a new phenomenon of X-ray-induced low-temper ature high-energy electron emission.« less

Tetrahydroxanthones from Mongolian medicinal plant Gentianella amarella ssp. acuta.

PubMed

Lu, Shuangxin; Tanaka, Naonobu; Kawazoe, Kazuyoshi; Murakami, Kotaro; Damdinjav, Davaadagva; Dorjbal, Enkhjargal; Kashiwada, Yoshiki

2016-10-01

Two tetrahydroxanthones, 1,3,5S,8S-tetrahydroxy-5,6,7,8-tetrahydroxanthone (1) and 1,3,5R,8S-tetrahydroxy-5,6,7,8-tetrahydroxanthone (2), and six new tetrahydroxanthone glycosides, amarellins A-F (3-8), were isolated from the aerial parts of a Mongolian medicinal plant Gentianella amarella ssp. acuta (Gentianaceae). The structures of 1-8 were elucidated on the basis of spectroscopic analysis, chemical conversion, and ECD calculation. Amarellins A-C (3-5) were assigned as 8-O-β-D-glucoside, 8-O-β-D-xyloside, and 1-O-β-D-glucoside of 1, respectively, while amarellins D-F (6-8) were elucidated to be 8-O-β-D-xyloside, 1-O-β-D-glucoside, and 3-O-β-D-glucoside of 2, respectively.

The Phase Transformation and Crystal Structure Studies of Strontium Substituted Barium Monoferrite

NASA Astrophysics Data System (ADS)

Mulyawan, A.; Adi, W. A.; Mustofa, S.; Fisli, A.

2017-03-01

Unlike other AFe2O4 ferrite materials, Barium Monoferrite (BaFe2O4) have an orthorhombic structure which is very interesting to further study the crystal structure and phase formation. In this study, Strontium substituted Barium Monoferrite in the form of Ba(1-x)Sr(x)Fe2O4 has successfully been synthesized through solid state reaction method which includes BaCO3, SrCO3, and Fe2O3 as starting materials. Ba(1-x)Sr(x)Fe2O4 was made by varying the dopant composition of Strontium (Sr2+) from x = 0, 0.1, 0.3, and 0.5. Each composition was assisted by ethanol and continued to the milling process for 5 hours then followed by sintering process at 900 °C for 5 hours. The phase transformation was studied by using X-ray diffractometer (XRD) and Rietveld refinement using General Structure Analysis System (GSAS) also 3D crystal visualization using VESTA. Referring to the refinement results, a single phase of BaFe2O4 was formed in x = 0 and 0.1. The composition has orthorhombic structure, space group B b21m, and lattice parameters of a = 19.0229, b = 5.3814 c = 8.4524 Å, α = β = γ = 90° and a = 18.9978, b = 5.3802 c = 8.4385 Å, α = β = γ = 90° respectively. In the composition of x = 0.3 it was found that the phase of BaSrFe4O8 begin to form due to the overload expansion of the Sr2+ occupancy which made the distortion of the initial lattice parameters and finally in the x = 0.5 composition the single phase of BaSrFe4O8 was clearly formed. Energy Dispersive Spectroscopy (EDS) was used to confirm the change of the material structure by measuring the elemental compound composition ratio. The result of EDS spectra clearly exhibited the dominant elements were Barium (Ba), Strontium (Sr), Iron (Fe), and Oxygen (O) with the compound ratio (Atomic percentage and mass percentage) correspond to the BaFe2O4 and BaSrFe4O8 phase.

Palladium complexes of a phosphorus ylide with two stabilizing groups: synthesis, structure, and DFT study of the bonding modes.

PubMed

Falvello, Larry R; Ginés, Juan Carlos; Carbó, Jorge J; Lledós, Agustí; Navarro, Rafael; Soler, Tatiana; Urriolabeitia, Esteban P

2006-08-21

The phosphorus ylide ligand [Ph3P=C(CO2Me)C(=NPh)CO2Me] (L1) has been prepared and fully characterized by spectroscopic, crystallographic, and density functional theory (DFT) methods (B3LYP level). The reactivity of L1 toward several cationic Pd(II) and Pt(II) precursors, with two vacant coordination sites, has been studied. The reaction of [M(C/\\X)(THF)2]ClO4 with L1 (1:1 molar ratio) gives [M(C/\\X)(L1)]ClO4 [M = Pd, C/\\X = C6H4CH2NMe2 (1), S-C6H4C(H)MeNMe2 (2), CH2-8-C9H6N (3), C6H4-2-NC5H4 (4), o-CH2C6H4P(o-tol)2 (6), eta3-C3H5 (7); M = Pt, C/\\X = o-CH2C6H4P(o-tol)2 (5); M(C/\\X) = Pd(C6F5)(SC4H8) (8), PdCl2 (9)]. In complexes 1-9, the ligand L1 bonds systematically to the metal center through the iminic N and the carbonyl O of the stabilizing CO2Me group, as is evident from the NMR data and from the X-ray structure of 3. Ligand L1 can also be orthopalladated by reaction with Pd(OAc)2 and LiCl, giving the dinuclear derivative [Pd(mu-Cl)(C6H4-2-PPh2=C(CO2Me)C(CO2Me)=NPh)]2 (10). The X-ray crystal structure of 10 is also reported. In none of the prepared complexes 1-10 was the C(alpha) atom found to be bonded to the metal center. DFT calculations and Bader analysis were performed on ylide L1 and complex 9 and its congeners in order to assess the preference of the six-membered N,O metallacycle over the four-membered C,N and five-membered C,O rings. The presence of two stabilizing groups at the ylidic C causes a reduction of its bonding capabilities. The increasing strength of the Pd-C, Pd-O, and Pd-N bonds along with other subtle effects are responsible for the relative stabilities of the different bonding modes.

New examples of ternary rare-earth metal boride carbides containing finite boron carbon chains: The crystal and electronic structure of RE15B6C20 (RE=Pr, Nd)

NASA Astrophysics Data System (ADS)

Babizhetskyy, Volodymyr; Mattausch, Hansjürgen; Simon, Arndt; Hiebl, Kurt; Ben Yahia, Mouna; Gautier, Régis; Halet, Jean-François

2008-08-01

The ternary rare-earth metal boride carbides RE15B6C20 (RE=Pr, Nd) were synthesized by co-melting the elements. They exist above 1270 K. Their crystal structures were determined from single-crystal X-ray diffraction data. Both crystallize in the space group P1¯, Z=1, a=8.3431(8) Å, b=9.2492(9) Å, c=8.3581(8) Å, α=84.72(1)°, β=89.68(1)°, γ =84.23(1)° (R1=0.041 (wR2=0.10) for 3291 reflections with Io>2σ(Io)) for Pr15B6C20, and a=8.284(1) Å, b=9.228(1) Å, c=8.309(1) Å, α=84.74(1)°, β=89.68(1)°, γ=84.17(2)° (R1=0.033 (wR2=0.049) for 2970 reflections with Io>2σ(Io)) for Nd15B6C20. Their structure consists of a three-dimensional framework of rare-earth metal atoms resulting from the stacking of slightly corrugated and distorted square nets, leading to cavities filled with unprecedented B2C4 finite chains, disordered C3 entities and isolated carbon atoms, respectively. Structural and theoretical analyses suggest the ionic formulation (RE3+)15([B2C4]6-)3([C3]4-)2(C4-)2·11ē. Accordingly, density functional theory calculations indicate that the compounds are metallic. Both structural arguments as well as energy calculations on different boron vs. carbon distributions in the B2C4 chains support the presence of a CBCCBC unit. Pr15B6C18 exhibits antiferromagnetic order at TN=7.9 K, followed by a meta-magnetic transition above a critical external field B>0.03 T. On the other hand, Nd15B6C18 is a ferromagnet below TC≈40 K.

Preparation and Characterization of an Amphipathic Magnetic Nanosphere

PubMed Central

Ji, Yongsheng; Lv, Ruihong; Xu, Zhigang; Zhao, Chuande; Zhang, Haixia

2014-01-01

The amphipathic magnetic nanospheres were synthesized using C8 and polyethylene glycol as ligands. Their morphology, structure, and composition were characterized by transmission electron microscope, Fourier transform infrared, and elementary analysis. The prepared materials presented uniform sphere with size distribution about 200 nm. The magnetic characteristics of magnetic nanomaterials were measured by vibrating sample magnetometer. The target products had a saturation magnetization value of 50 emu g−1 and superparamagnetism. The adsorption capability was also studied by static tests, and the material was applied to enrich benzenesulfonamide from calf serum. The results exhibited that the C8-PEG phase owned better adsorption capability, biocompatible property, and dispersivity in aqueous samples. PMID:24729917

8-O-Azeloyl-14-benzoylaconine: a new alkaloid from the roots of Aconitum karacolicum Rapcs and its antiproliferative activities.

PubMed

Chodoeva, Ainura; Bosc, Jean-Jacques; Guillon, Jean; Decendit, Alain; Petraud, Michel; Absalon, Christelle; Vitry, Christiane; Jarry, Christian; Robert, Jacques

2005-12-01

A new alkaloid of Aconitum karacolicum Rapcs, from the Ranunculaceae family, collected in Kirghizstan, was isolated from the roots of this plant, using a purification scheme based upon its in vitro antiproliferative properties against three human tumour cell lines in culture. Structural identification was performed using high resolution MS-MS mass spectrometry and (1)H, (13)C, 2D NOESY NMR spectroscopy analysis. This compound consists of a 14-benzoylaconine moiety substituted on C-8 by an azeloyl chain. It presents in vitro cytotoxicity with an IC(50) of about 10-20 microM, which warrants further investigation on its possible interest in cancer chemotherapy.

Solution structure and base pair opening kinetics of the i-motif dimer of d(5mCCTTTACC): a noncanonical structure with possible roles in chromosome stability.

PubMed

Nonin, S; Phan, A T; Leroy, J L

1997-09-15

Repetitive cytosine-rich DNA sequences have been identified in telomeres and centromeres of eukaryotic chromosomes. These sequences play a role in maintaining chromosome stability during replication and may be involved in chromosome pairing during meiosis. The C-rich repeats can fold into an 'i-motif' structure, in which two parallel-stranded duplexes with hemiprotonated C.C+ pairs are intercalated. Previous NMR studies of naturally occurring repeats have produced poor NMR spectra. This led us to investigate oligonucleotides, based on natural sequences, to produce higher quality spectra and thus provide further information as to the structure and possible biological function of the i-motif. NMR spectroscopy has shown that d(5mCCTTTACC) forms an i-motif dimer of symmetry-related and intercalated folded strands. The high-definition structure is computed on the basis of the build-up rates of 29 intraresidue and 35 interresidue nuclear Overhauser effect (NOE) connectivities. The i-motif core includes intercalated interstrand C.C+ pairs stacked in the order 2*.8/1.7*/1*.7/2.8* (where one strand is distinguished by an asterisk and the numbers relate to the base positions within the repeat). The TTTA sequences form two loops which span the two wide grooves on opposite sides of the i-motif core; the i-motif core is extended at both ends by the stacking of A6 onto C2.C8+. The lifetimes of pairs C2.C8+ and 5mC1.C7+ are 1 ms and 1 s, respectively, at 15 degrees C. Anomalous exchange properties of the T3 imino proton indicate hydrogen bonding to A6 N7 via a water bridge. The d(5mCCTTTTCC) deoxyoligonucleotide, in which position 6 is occupied by a thymidine instead of an adenine, also forms a symmetric i-motif dimer. However, in this structure the two TTTT loops are located on the same side of the i-motif core and the C.C+ pairs are formed by equivalent cytidines stacked in the order 8*.8/1.1*/7*.7/2.2*. Oligodeoxynucleotides containing two C-rich repeats can fold and dimerize into an i-motif. The change of folding topology resulting from the substitution of a single nucleoside emphasizes the influence of the loop residues on the i-motif structure formed by two folded strands.

Ultralight anisotropic foams from layered aligned carbon nanotube sheets

NASA Astrophysics Data System (ADS)

Faraji, Shaghayegh; L. Stano, Kelly; Yildiz, Ozkan; Li, Ang; Zhu, Yuntian; Bradford, Philip D.

2015-10-01

In this work, we present large scale, ultralight aligned carbon nanotube (CNT) structures which have densities an order of magnitude lower than CNT arrays, have tunable properties and exhibit resiliency after compression. By stacking aligned sheets of carbon nanotubes and then infiltrating with a pyrolytic carbon (PyC), resilient foam-like materials were produced that exhibited complete recovery from 90% compressive strain. With density as low as 3.8 mg cm-3, the foam structure is over 500 times less dense than bulk graphite. Microscopy revealed that PyC coated the junctions among CNTs, and also increased CNT surface roughness. These changes in the morphology explain the transition from inelastic behavior to foam-like recovery of the layered CNT sheet structure. Mechanical and thermal properties of the foams were tuned for different applications through variation of PyC deposition duration while dynamic mechanical analysis showed no change in mechanical properties over a large temperature range. Observation of a large and linear electrical resistance change during compression of the aligned CNT/carbon (ACNT/C) foams makes strain/pressure sensors a relevant application. The foams have high oil absorption capacities, up to 275 times their own weight, which suggests they may be useful in water treatment and oil spill cleanup. Finally, the ACNT/C foam's high porosity, surface area and stability allow for demonstration of the foams as catalyst support structures.In this work, we present large scale, ultralight aligned carbon nanotube (CNT) structures which have densities an order of magnitude lower than CNT arrays, have tunable properties and exhibit resiliency after compression. By stacking aligned sheets of carbon nanotubes and then infiltrating with a pyrolytic carbon (PyC), resilient foam-like materials were produced that exhibited complete recovery from 90% compressive strain. With density as low as 3.8 mg cm-3, the foam structure is over 500 times less dense than bulk graphite. Microscopy revealed that PyC coated the junctions among CNTs, and also increased CNT surface roughness. These changes in the morphology explain the transition from inelastic behavior to foam-like recovery of the layered CNT sheet structure. Mechanical and thermal properties of the foams were tuned for different applications through variation of PyC deposition duration while dynamic mechanical analysis showed no change in mechanical properties over a large temperature range. Observation of a large and linear electrical resistance change during compression of the aligned CNT/carbon (ACNT/C) foams makes strain/pressure sensors a relevant application. The foams have high oil absorption capacities, up to 275 times their own weight, which suggests they may be useful in water treatment and oil spill cleanup. Finally, the ACNT/C foam's high porosity, surface area and stability allow for demonstration of the foams as catalyst support structures. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03899e

Density functional theory calculations in stereochemical determination of terpecurcumins J-W, cytotoxic terpene-conjugated curcuminoids from Curcuma longa L.

PubMed

Lin, Xionghao; Ji, Shuai; Qiao, Xue; Hu, Hongbo; Chen, Ni; Dong, Yinhui; Huang, Yun; Guo, Dean; Tu, Pengfei; Ye, Min

2013-12-06

Fourteen novel terpene-conjugated curcuminoids, terpecurcumins J-W (1-14), have been isolated from the rhizomes of Curcuma longa L. Among them, terpecurcumins J-Q and V represent four unprecedented skeletons featuring an unusual core of hydrobenzannulated[6,6]-spiroketal (1 and 2), bicyclo[2.2.2]octene (3-7), bicyclo[3.1.3]octene (8), and spiroepoxide (13), respectively. The structures of compounds 1-14 were elucidated by extensive spectroscopic analysis, and their absolute configurations were established by electronic circular dichroism, vibrational circular dichroism, and (13)C NMR spectroscopic data analysis, together with density functional theory calculations. The structure and configuration of 1 was further confirmed by single-crystal X-ray diffraction (Cu Kα). The biogenetic pathways of 1-14 were proposed, involving Michael addition, condensation, Diels-Alder cycloaddition, and electrophilic substitution reactions. Terpecurcumins showed more potent cytotoxic activities than curcumin and ar-/β-turmerone. Among them, terpecurcumin Q (8) exhibited IC50 of 3.9 μM against MCF-7 human breast cancer cells, and mitochondria-mediated apoptosis played an important role in the overall growth inhibition. Finally, LC/MS/MS quantitative analysis of five representative terpecurcumins indicated these novel compounds were present in C. longa at parts per million level.

Structural basis for the mutual antagonism of cAMP and TRIP8b in regulating HCN channel function

PubMed Central

Saponaro, Andrea; Pauleta, Sofia R.; Cantini, Francesca; Matzapetakis, Manolis; Hammann, Christian; Donadoni, Chiara; Hu, Lei; Thiel, Gerhard; Banci, Lucia; Santoro, Bina; Moroni, Anna

2014-01-01

cAMP signaling in the brain mediates several higher order neural processes. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels directly bind cAMP through their cytoplasmic cyclic nucleotide binding domain (CNBD), thus playing a unique role in brain function. Neuronal HCN channels are also regulated by tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b), an auxiliary subunit that antagonizes the effects of cAMP by interacting with the channel CNBD. To unravel the molecular mechanisms underlying the dual regulation of HCN channel activity by cAMP/TRIP8b, we determined the NMR solution structure of the HCN2 channel CNBD in the cAMP-free form and mapped on it the TRIP8b interaction site. We reconstruct here the full conformational changes induced by cAMP binding to the HCN channel CNBD. Our results show that TRIP8b does not compete with cAMP for the same binding region; rather, it exerts its inhibitory action through an allosteric mechanism, preventing the cAMP-induced conformational changes in the HCN channel CNBD. PMID:25197093

0.8 V nanogenerator for mechanical energy harvesting using bismuth titanate-PDMS nanocomposite

NASA Astrophysics Data System (ADS)

Abinnas, N.; Baskaran, P.; Harish, S.; Ganesh, R. Sankar; Navaneethan, M.; Nisha, K. D.; Ponnusamy, S.; Muthamizhchelvan, C.; Ikeda, H.; Hayakawa, Y.

2017-10-01

We present a novel, low-cost approach to fabricate piezoelectric nanogenerators using Bismuth titanate (BiT)/Polydimethylsiloxane (PDMS) nanocomposite. The nanogenerator has the advantage of the simple process of fabrication and is eco-friendly. This simple device was fabricated to harvest the energy released from finger tapping. This device generated an output of 0.8 V. The BiT samples were synthesized by wet chemical method. The structural, dielectric and ferroelectric properties of the samples were analyzed. Phase analysis using X-ray diffraction indicated that the phase structure was orthorhombic. The FESEM images of the sample calcined at 700 °C exhibited sheet-like morphology. Further characterizations like XPS, Raman studies, TEM were done.

Structural analysis and characterization of layer perovskite oxynitrides made from Dion Jacobson oxide precursors

NASA Astrophysics Data System (ADS)

Schottenfeld, Joshua A.; Benesi, Alan J.; Stephens, Peter W.; Chen, Gugang; Eklund, Peter C.; Mallouk, Thomas E.

2005-07-01

A three-layer oxynitride Ruddlesden-Popper phase Rb 1+xCa 2Nb 3O 10-xN x· yH 2O ( x=0.7-0.8, y=0.4-0.6) was synthesized by ammonialysis at 800 °C from the Dion-Jacobson phase RbCa 2Nb 3O 10 in the presence of Rb 2CO 3. Incorporation of nitrogen into the layer perovskite structure was confirmed by XPS, combustion analysis, and MAS NMR. The water content was determined by thermal gravimetric analysis and the rubidium content by ICP-MS. A similar layered perovskite interconversion occurred in the two-layer Dion-Jacobson oxide RbLaNb 2O 7 to yield Rb 1+xLaNb 2O 7-xN x· yH 2O ( x=0.7-0.8, y=0.5-1.0). Both compounds were air- and moisture-sensitive, with rapid loss of nitrogen by oxidation and hydrolysis reactions. The structure of the three-layer oxynitride Rb 1.7Ca 2Nb 3O 9.3N 0.7·0.5H 2O was solved in space group P4 /mmm with a=3.887(3) and c=18.65(1) Å, by Rietveld refinement of X-ray powder diffraction data. The two-layer oxynitride structure Rb 1.8LaNb 2O 6.3N 0.7·1.0H 2O was also determined in space group P4 /mmm with a=3.934(2) and c=14.697(2) Å. GSAS refinement of synchrotron X-ray powder diffraction data showed that the water molecules were intercalated between a double layer of Rb+ ions in both the two- and three-layer Ruddlesden-Popper structures. Optical band gaps were measured by diffuse reflectance UV-vis for both materials. An indirect band gap of 2.51 eV and a direct band gap of 2.99 eV were found for the three-layer compound, while an indirect band gap of 2.29 eV and a direct band gap of 2.84 eV were measured for the two-layer compound. Photocatalytic activity tests of the three-layer compound under 380 nm pass filtered light with AgNO 3 as a sacrificial electron acceptor gave a quantum yield of 0.025% for oxygen evolution.

Sequence characterization of S100A8 gene reveals structural differences of protein and transcriptional factor binding sites in water buffalo and yak.

PubMed

Kathiravan, P; Goyal, S; Kataria, R S; Mishra, B P; Jayakumar, S; Joshi, B K

2011-01-01

The present study was undertaken to characterize the structure of S100A8 gene and its promoter in water buffalo and yak. Sequence data of 2.067 kb, 2.071 kb, and 2.052 kb with respect to complete S100A8 gene including 5' flanking region was generated in river buffalo, swamp buffalo, and yak, respectively. BLAST analysis of coding DNA sequences (CDS) of S100A8 gene revealed 95% homology of buffalo sequence with cattle, 85% with pig and horse, 83% with dog, 72-73% with murines, and around 79% with primates and humans. Phylogenetic analysis of predicted CDS revealed distinct clustering of murines, primates, and domestic animals with bovines and bubalines forming a subcluster among farm animals. In silico translation of predicted CDS revealed a sequence of 89 amino acids with 7 amino acid changes between cattle and buffalo and 2 changes between cattle and yak. The search for Pfam family revealed the N-terminal calcium binding domain and the noncanonical EF hand domain in the carboxy terminus, with more variations being observed in the N-terminal domain among different species. Two amino acid changes observed in carboxy terminal EF hand domain resulted in altered secondary structure of yak S100A8 protein. Analysis of S100A8 gene promoter revealed 14 putative motifs for transcriptional factor binding sites. Two putative motifs viz. C/EBP and v-Myb were found to be absent in swamp buffalo as compared to river buffalo and cattle. Differences in the structure of S100A8 protein and the transcriptional factor binding sites identified in the present study need to be analyzed further for their functional significance in yak and swamp buffalo respectively. Copyright © Taylor & Francis Group, LLC

Population genetics of Cryptosporidium meleagridis in humans and birds: evidence for cross-species transmission.

PubMed

Wang, Yuanfei; Yang, Wenli; Cama, Vitaliano; Wang, Lin; Cabrera, Lilia; Ortega, Ynes; Bern, Caryn; Feng, Yaoyu; Gilman, Robert; Xiao, Lihua

2014-07-01

Population genetic studies have been used to understand the transmission of pathogens in humans and animals, especially the role of zoonotic infections and evolution and dispersal of virulent subtypes. In this study, we analysed the genetic diversity and population structure of Cryptosporidium meleagridis, the only known Cryptosporidium species that infects both avian and mammalian hosts and is responsible for approximately 10% of human cryptosporidiosis in some areas. A total of 62 C. meleagridis specimens from children, AIDS patients, and birds in Lima, Peru were characterised by sequence analysis of the ssrRNA gene and five minisatellite, microsatellite and polymorphic markers in chromosome 6, including the 60 kDa glycoprotein (gp60), 47 kDa glycoprotein (CP47), a serine repeat antigen (MSC6-5), retinitis pigmentosa GTPase regulator (RPGR) and thrombospondin protein 8 (TSP8). The multilocus sequence analysis identified concurrent infections with Cryptosporidium hominis in four AIDS patients and three children. Unique subtypes of C. meleagridis ranged from eight at the gp60 locus (gene diversity -Hd=0.651), three at the RPGR (Hd=0.556), three at the MSC6-5 locus (Hd=0.242), two at TSP8 (Hd=0.198), to one at CP47 (monomorphic), much lower than that of C. hominis in the same area. Intragenic linkage disequilibrium was strong and complete at all gene loci. Intergenic linkage disequilibrium was highly significant (P<0.001) for all pairs of polymorphic loci. Two major groups of subtypes were seen, with most subtypes belonging to group 1. Within group 1, there was no clear population segregation, and two of the 14 multilocus subtypes of C. meleagridis were found in both AIDS patients and birds. We believe that these results provide the first evidence of a clonal population structure of C. meleagridis and the likely occurrence of cross-species transmission of C. meleagridis between birds and humans. Published by Elsevier Ltd.

Synthesis and antibacterial activity of bis-[2-hydroxy-3-(1,7,8,9,10-pentamethyl-3,5-dioxo-4-aza-tricyclo[5.2.1.0(2,6)]dec-8-en-4-yloxy)-propyl]-dimethyl-ammonium chloride.

PubMed

Struga, Marta; Kossakowski, Jerzy; Stefańska, Joanna; Zimniak, Andrzej; Koziol, Anna E

2008-06-01

A new quaternary ammonium compound, bis-[2-hydroxy-3-(1,7,8,9,10-pentamethyl-3,5-dioxo-4-aza-tricyclo[5.2.1.0(2,6)]dec-8-en-4-yloxy)-propyl]-dimethyl-ammonium chloride (4), was synthesized. The compound was investigated for antibacterial activity, including Gram-positive cocci and Gram-negative rods, and antifungal activity. Compound 4 showed significant inhibition against Staphylococcus aureus. Research was carried out over 4 standard strains and 40 hospital strains. Elementary analysis and/or MS, (1)H NMR and (13)C NMR spectra confirmed the identity of the products. The molecular structure of 3 was determined by an X-ray analysis.

Correlations of phase structure and thermal stability for Alnico 8 alloys

NASA Astrophysics Data System (ADS)

Zhao, J. T.; Sun, Y. L.; Liu, L.; Lee, D.; Liu, Z.; Feng, X. C.; Yan, A. R.

2017-11-01

The correlations of phase structure and thermal stability for Alnico 8 alloys is analyzed by three-step aging at 650 °C, 600 °C and 550 °C gradually in this paper. After three-step aging the a1 phase is a chess-like structure in transverse direction and a bamboo-like structure in longitudinal direction. Meanwhile the magnetic energy product ((BH)m) increases from 9.17 MGOe to 10.59 MGOe, and the remanence temperature coefficient a(RT-180 °C) reduces from -2.31 %%/°C to -1.25 %%/°C. The MPMS and VSM measurements indicate that three-step aging makes the a1 phase be single domain particles and dispersed distribution, which plays an important role in optimizing the thermal stability of Alnico alloys.

Synthesis and biological activities of novel 5-substituted-1,3,4-oxadiazole Mannich bases and bis-Mannich bases as ketol-acid reductoisomerase inhibitors.

PubMed

Zhang, Yan; Liu, Xing-Hai; Zhan, Yi-Zhou; Zhang, Li-Yuan; Li, Zheng-Ming; Li, Yong-Hong; Zhang, Xiao; Wang, Bao-Lei

2016-10-01

A series of novel 5-substituted-1,3,4-oxadiazole Mannich bases and bis-Mannich bases have been conveniently synthesized in good yields. Their structures were characterized by IR, (1)H NMR, (13)C NMR and elemental analysis. The preliminary bioassay results indicated that some of the compounds showed promising in vitro fungicidal activities towards several test plant fungi; some of them exhibited significant herbicidal activities against Brassica campestris and excellent in vitro inhibitory activities against rice ketol-acid reductoisomerase (KARI). Among 14 novel compounds, 8c, 8d and 8m showed potent KARI inhibitory activities with Ki value of (0.96±0.42), (3.86±0.49) and (3.10±0.71) μmol/L, respectively, and were comparable with IpOHA. These compounds could be novel KARI inhibitors for further investigation. The density functional theory (DFT) calculations and molecular docking were carried out to study the structure-activity relationship (SAR) of the active inhibitors in this Letter. Copyright © 2016 Elsevier Ltd. All rights reserved.

Functional analysis reveals the possible role of the C-terminal sequences and PI motif in the function of lily (Lilium longiflorum) PISTILLATA (PI) orthologues

PubMed Central

Chen, Ming-Kun; Hsieh, Wen-Ping; Yang, Chang-Hsien

2012-01-01

Two lily (Lilium longiflorum) PISTILLATA (PI) genes, Lily MADS Box Gene 8 and 9 (LMADS8/9), were characterized. LMADS9 lacked 29 C-terminal amino acids including the PI motif that was present in LMADS8. Both LMADS8/9 mRNAs were prevalent in the first and second whorl tepals during all stages of development and were expressed in the stamen only in young flower buds. LMADS8/9 could both form homodimers, but the ability of LMADS8 homodimers to bind to CArG1 was relatively stronger than that of LMADS9 homodimers. 35S:LMADS8 completely, and 35S:LMADS9 only partially, rescued the second whorl petal formation and partially converted the first whorl sepal into a petal-like structure in Arabidopsis pi-1 mutants. Ectopic expression of LMADS8-C (with deletion of the 29 amino acids of the C-terminal sequence) or LMADS8-PI (with only the PI motif deleted) only partially rescued petal formation in pi mutants, which was similar to what was observed in 35S:LMADS9/pi plants. In contrast, 35:LMADS9+L8C (with the addition of the 29 amino acids of the LMADS8 C-terminal sequence) or 35S:LMADS9+L8PI (with the addition of the LMADS8 PI motif) demonstrated an increased ability to rescue petal formation in pi mutants, which was similar to what was observed in 35S:LMADS8/pi plants. Furthermore, ectopic expression of LMADS8-M (with the MADS domain truncated) generated more severe dominant negative phenotypes than those seen in 35S:LMADS9-M flowers. These results revealed that the 29 amino acids including the PI motif in the C-terminal region of the lily PI orthologue are valuable for its function in regulating perianth organ formation. PMID:22068145

Crystallization and preliminary X-ray analysis of recombinant human acid beta-glucocerebrosidase, a treatment for Gaucher's disease

NASA Technical Reports Server (NTRS)

Roeber, Dana; Achari, Aniruddha; Manavalan, Partha; Edmunds, Tim; Scott, David L.

2003-01-01

Acid beta-glucocerebrosidase (N-acylsphingosyl-1-O-beta-D-glucoside:glucohydrolase) is a lysosomal glycoprotein that catalyzes the hydrolysis of the glycolipid glucocerebroside to glucose and ceramide. Inadequate levels of this enzyme underly the pathophysiology of Gaucher's disease. Cerezyme (Genzyme Corporation, Cambridge, MA, USA) is a partially deglycosylated form of recombinant human acid beta-glucocerebrosidase that is used in the treatment of Gaucher patients. Although acid beta-glucocerebrosidase belongs to a large family of glycosidases, relatively little is known regarding its structural biology. Here, the crystallization and the initial diffraction analysis of Cerezyme are reported. The crystals are C-centered orthorhombic, with unit-cell parameters a = 285.0, b = 110.2, c = 91.7 A. A 99.9% complete data set has been collected to 2.75 A with an R(sym) of 8.8%.

Crystallization and Preliminary X-ray analysis of Human Recombinant Acid beta-glucocerebrosidase, a treatment for Gaucher's Disease

NASA Technical Reports Server (NTRS)

Roeber, Dana F.; Achari, Aniruddha; Manavalan, Partha; Edmunds, Tim; Scott, David L.; Curreri, Peter A. (Technical Monitor)

2002-01-01

Acid beta-glucocerebrosidase (N-acylsphingosyl - O - beta-D - glucoside:glucohydrolase) is a lysosomal glycoprotein that catalyzes the hydrolysis of the glycolipid glucocerebroside to glucose and ceramide. Inadequate levels of this enzyme underly the pathophysiology of Gaucher's disease. Cerezyme(R) (Genzyme Corporation, Cambridge, MA) is a partially deglycosylated form of recombinant human acid beta-glucocerebrosidase that is commercially available for the treatment of Gaucher patients. Although acid beta-glucocerebrosidase belongs to a large family of glycosidases, relatively little is known regarding its structural biology. We report the crystallization and the initial diffraction analysis of Cerezyme(R). The crystals are C-centered orthorhombic, with unit-cell parameters of a = 285.0 A, b = 110.2 A, and c = 91.7 A. A 99.9 A complete data set has been collected to 2.75 A with an R(sub sym) of 8.8 %.

Synthesis, Dielectric, Electrical and Optical characterization of ZnO synthesized by chemical route using polymer precursors

NASA Astrophysics Data System (ADS)

Mishra, Raman; Bajpai, P. K.

2011-11-01

Nano-size ZnO (particle size 7.8 nm) have been prepared from a versatile, efficient and technically simple polymer matrix based precursor solution. The precursor solution constituted of zinc nitrates with polymer PVA in presence of mono-/disaccharides. Annealing the precursor mass at 900 °C single phase zinc oxide nano-particles are obtained. X-ray diffraction analysis confirms hexagonal crystal structure with lattice parameter a = b = 3.261 A0, c = 5.220 A0. The estimated average particle size obtained from XRD data is ≈7.8 nm. The impedance analysis reveals that the grain resistance decreases with increase in temperature as expected for a semi-conducting material. The relaxation is polydispersive and conduction is mainly through grains. Optical properties and AC/DC conduction activation energies are estimated from Arrhenius plots and conduction mechanism is discussed.

Localization of human coagulation factor VIII (hFVIII) in transgenic rabbit by FISH-TSA: identification of transgene copy number and transmission to the next generation.

PubMed

Krylov, V; Tlapáková, T; Mácha, J; Curlej, J; Ryban, L; Chrenek, P

2008-01-01

For chromosomal localization of the hFVIII human transgene in F2 and F3 generation of transgenic rabbits, FISH-TSA was applied. A short cDNA probe (1250 bp) targeted chromosomes 3, 7, 8, 9 and 18 of an F2 male (animal 1-3-8). Two transgenic offspring (F3) revealed signal positions in chromosome 3 and chromosomes 3 and 7, respectively. Sequencing and structure analysis of the rabbit orthologous gene revealed high similarity to its human counterpart. Part of the sequenced cDNA (1310 bp) served as a probe for FISH-TSA analysis. The rabbit gene was localized in the q arm terminus of the X chromosome. This result is in agreement with reciprocal chromosome painting between the rabbit and the human. The presented FISH-TSA method provides strong signals without any interspecies reactivity.

Layered Structures and Disordered Polyanionic Nets in the Cation-Poor Polar Intermetallics CsAu 1.4 Ga 2.8 and CsAu 2 Ga 2.6

DOE PAGES

Smetana, Volodymyr; Steinberg, Simon; Mudring, Anja-Verena

2016-12-27

Gold intermetallics are known for their unusual structures and bonding patterns. Two new compounds have been discovered in the cation-poor part of the Cs–Au–Ga system. We obtained both compounds directly by heating the elements at elevated temperatures. Structure determinations based on single-crystal X-ray diffraction analyses revealed two structurally and compositionally related formations: CsAu 1.4Ga 2.8 (I) and CsAu 2Ga 2.6 (II) crystallize in their own structure types (I: Rmore » $$\\bar{3}$$, a = 11.160(2) Å, c = 21.706(4) Å, Z = 18; II: R$$\\bar{3}$$, a = 11.106(1) Å, Å, c = 77.243(9) Å, Z = 54) and contain hexagonal cationic layers of cesium. Furthermore, this is a unique structural motif, which has never been observed for the other (lighter) alkali metals in combination with Au and post transition elements. The polyanionic part is characterized in contrast by Au/Ga tetrahedral stars, a structural feature that is characteristic for light alkali metal representatives, and disordered sites with mixed Au/Ga occupancies that occur in both structures with a more significant disorder in the polyanionic component of CsAu 2Ga 2.6. Examinations of the electronic band structure for a model approximating the composition of CsAu 1.4Ga 2.8 have been completed using density-functional-theory-based methods and reveal a deep pseudogap at E F. Bonding analysis by evaluating the crystal orbital Hamilton populations show dominant heteroatomic Au–Ga bonds and only a negligible contribution from Cs pairs.« less

High-Resolution Infrared and Electron-Diffraction Studies of Trimethylenecyclopropane ([3]-Radialene)

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

Wright, Corey; Holmes, Joshua; Nibler, Joseph W.

2013-05-16

Combined high-resolution spectroscopic, electron-diffraction, and quantum theoretical methods are particularly advantageous for small molecules of high symmetry and can yield accurate structures that reveal subtle effects of electron delocalization on molecular bonds. The smallest of the radialene compounds, trimethylenecyclopropane, [3]-radialene, has been synthesized and examined in the gas phase by these methods. The first high-resolution infrared spectra have been obtained for this molecule of D3h symmetry, leading to an accurate B0 rotational constant value of 0.1378629(8) cm-1, within 0.5% of the value obtained from electronic structure calculations (density functional theory (DFT) B3LYP/cc-pVTZ). This result is employed in an analysis ofmore » electron-diffraction data to obtain the rz bond lengths (in Å): C-H = 1.072 (17), C-C = 1.437 (4), and C=C = 1.330 (4). The analysis does not lead to an accurate value of the HCH angle; however, from comparisons of theoretical and experimental angles for similar compounds, the theoretical prediction of 117.5° is believed to be reliable to within 2°. The effect of electron delocalization in radialene is to reduce the single C-C bond length by 0.07 Å compared to that in cyclopropane.« less

Synthesis, properties and crystal structure of (Gly) 2H 4SiW 12O 40·5.5H 2O

NASA Astrophysics Data System (ADS)

Lihua, Bi; Qizhuang, He; Qiong, Jia; Enbo, Wang

2001-10-01

A novel polyoxometalate containing Glycine (Gly), (Gly)2H4SiW12O40·5.5H2O (I), has been synthesized and characterized by single-crystal X-ray diffraction, elemental analyzes, IR spectrum, cyclic voltammograms and thermogravimetric analysis. The compound crystallizes in the monoclinic space group C2/C with a=40.362 (8) Å, b=12.478 (3) Å, c=19.879 (4) Å, β=96.22 (3)°, V=9953 (4) Å3, Z=8 and R1 (wR2)=0.0699 (0.1609). The crystal structure consists of [SiW12O40]4- units linked together with Gly molecules through hydrogen bonding. The electrochemical properties of I showed that the electrode reaction is surface-controlled. The compound has photosensitivity under irradiation of sunlight to result in charge transfer by oxidation of Gly and the reduction of SiW12O404-. We also found that the compound exhibited effectiveness in preventing cucumber mosaic virus (CMV).

4-[2-(4-cyanophenyl)ethenyl]-N-methylpyridinium tetraphenylborate.

PubMed

Jin, Dan; Zhang, De Chun

2005-11-01

In the title compound, C(15)H(13)N(2)(+).C(24)H(20)B(-), the pyridyl ring of the cation makes a dihedral angle of 1.6 degrees with the benzene ring. Each is rotated in the same direction with respect to the central -C-CH=CH-C- linkage, by 3.8 and 5.3 degrees, respectively. The anions have a slightly distorted tetrahedral geometry. Molecular packing analysis was carried out using the packing energy portioning scheme in the program OPEC. Around each anion in the crystal structure there are eight anions, which interact with the central anion through C-H...pi interactions. The cations are hydrogen bonded in a head-to-tail fashion, forming chains along [101].

Synthesis and characterization of nanocrystalline Co-Fe-Nb-Ta-B alloy

NASA Astrophysics Data System (ADS)

Raanaei, Hossein; Fakhraee, Morteza

2017-09-01

In this research work, structural and magnetic evolution of Co57Fe13Nb8Ta4B18 alloy, during mechanical alloying process, have been investigated by using, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron dispersive X-ray spectroscopy, differential thermal analysis and also vibrating sample magnetometer. It is observed that at 120 milling time, the crystallite size reaches to about 7.8 nm. Structural analyses show that, the solid solution of the initial powder mixture occurs at160 h milling time. The coercivity behavior demonstrates a rise, up to 70 h followed by decreasing tendency up to final stage of milling process. Thermal analysis of 160 h milling time sample reveals two endothermic peaks. The characterization of annealed milled sample for 160 h milling time at 427 °C shows crystallite size growth accompanied by increasing in saturation magnetization.

Orthorhombic YBaCo{sub 4}O{sub 8.4} crystals as a result of saturation of hexagonal YBaCo{sub 4}O{sub 7} crystals with oxygen

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

Podberezskaya, N. V., E-mail: podberez@niic.nsc.ru; Bolotina, N. B., E-mail: nb-bolotina@mail.ru; Komarov, V. Yu., E-mail: komarov-v-y@niic.nsc.ru

Hexagonal YBaCo{sub 4}O{sub 7} crystals (sp. gr. P6{sub 3}mc, a{sub h} = 6.3058(4) Å, c{sub h} = 10.2442(7) Å, Z = 2) are saturated with oxygen to the YBaCo{sub 4}O{sub 8.4} composition and studied by X-ray diffraction (XRD) analysis. The saturation is completed by a structural first-order phase transition to orthorhombic crystals (sp. gr. Pbc2{sub 1}, a{sub o} = 31.8419(2) Å, b{sub o} = 10.9239(5) Å, c{sub o} = 10.0960(5) Å, Z = 20). The connection of two lattices is expressed in terms of the action of matrix (500/120/001) on the hexagonal basis. Five structural fragments of the same typemore » but with different degrees of order alternate along the long axis of the oxygen-saturated orthorhombic structure. The XRD data on single crystals differ from the results obtained by other researchers on ceramic samples; possible causes of these differences are discussed.« less

A phase transition caught in mid-course: independent and concomitant analyses of the monoclinic and triclinic structures of (nBu4N)[Co(orotate)2(bipy)]·3H2O

PubMed Central

Castro, Miguel; Falvello, Larry R.; Forcén-Vázquez, Elena; Al-Kenany, Nuha A.; Martínez, Gema

2017-01-01

The preparation and characterization of the nBu4N+ salts of two bis-orotate(2−) complexes of cobalt, namely bis­(tetra-n-butyl­ammonium) di­aqua­bis­(2,4-dioxo-1,2,3,4-tetra­hydro­pyrimidin-1-ide-6-carboxyl­ato-κ2 N 1,O 6)cobalt(II) 1.8-hydrate, (C16H36N)2[Co(C5H2N2O4)2(H2O)2]·1.8H2O, (1), and tetra-n-butyl­ammonium (2,2′-bi­pyridine-κ2 N,N′)bis­(2,4-dioxo-1,2,3,4-tetra­hydro­pyrimidin-1-ide-6-carbox­yl­ato-κ2 N 1,O 6)cobalt(III) trihydrate, (C16H36N)[Co(C5H2N2O4)2(C10H8N2)]·3H2O, (2), are reported. The CoIII complex, (2), which is monoclinic at room tem­perature, presents a conservative single-crystal-to-single-crystal phase transition below 200 K, producing a triclinic twin. The transition, which involves a conformational change in one of the nBu groups of the cation, is reversible and can be cycled. Both end phases have been characterized structurally and the system was also characterized structurally in a two-phase inter­mediate state, using single-crystal diffraction techniques, with both the monoclinic and triclinic phases present. Thermal analysis allows a rough estimate of the small energy content, viz. 0.25 kJ mol−1, for both the monoclinic-to-triclinic transformation and the reverse transition, in agreement with the nature of the structural changes involving only the nBu4N+ cation. PMID:28872072

(±)-Pestalachloride D, an antibacterial racemate of chlorinated benzophenone derivative from a soft coral-derived fungus Pestalotiopsis sp.

PubMed

Wei, Mei-Yan; Li, Dan; Shao, Chang-Lun; Deng, Dong-Sheng; Wang, Chang-Yun

2013-03-28

A new antibacterial chlorinated benzophenone derivative, (±)-pestalachloride D (1), along with a related analog, (±)-pestalachloride C (2), was recently isolated from the marine-derived fungus Pestalotiopsis sp. isolated from a soft coral Sarcophyton sp. collected from Yongxing Island in the South China Sea. Both chiral HPLC analysis and single-crystal X-ray data indicated that 1 is a racemic mixture. Interestingly, 1 did not exhibit any effect in the zebrafish embryo teratogenicity assay, while 2 led to abnormal growth. The potential impact on zebrafish embryo growth is discussed based on their crystal structures. The main difference of crystal structures between 1 and 2 is that the six-member non-aromatic ring (O4, C10, C9, C8, C2', and C3') in 1 exhibits a distorted chair conformation, while 2 shows a distorted boat conformation. Moreover, compounds 1 and 2 both exhibited moderate antibacterial activity.

(±)-Pestalachloride D, an Antibacterial Racemate of Chlorinated Benzophenone Derivative from a Soft Coral-Derived Fungus Pestalotiopsis sp

PubMed Central

Wei, Mei-Yan; Li, Dan; Shao, Chang-Lun; Deng, Dong-Sheng; Wang, Chang-Yun

2013-01-01

A new antibacterial chlorinated benzophenone derivative, (±)-pestalachloride D (1), along with a related analog, (±)-pestalachloride C (2), was recently isolated from the marine-derived fungus Pestalotiopsis sp. isolated from a soft coral Sarcophyton sp. collected from Yongxing Island in the South China Sea. Both chiral HPLC analysis and single-crystal X-ray data indicated that 1 is a racemic mixture. Interestingly, 1 did not exhibit any effect in the zebrafish embryo teratogenicity assay, while 2 led to abnormal growth. The potential impact on zebrafish embryo growth is discussed based on their crystal structures. The main difference of crystal structures between 1 and 2 is that the six-member non-aromatic ring (O4, C10, C9, C8, C2′, and C3′) in 1 exhibits a distorted chair conformation, while 2 shows a distorted boat conformation. Moreover, compounds 1 and 2 both exhibited moderate antibacterial activity. PMID:23538869

Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

DOE PAGES

Ghafoor, Naureen; Eriksson, Fredrik; Aquila, Andrew; ...

2017-01-01

We investigate the influence of B 4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization nearmore » Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.« less

Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

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

Ghafoor, Naureen; Eriksson, Fredrik; Aquila, Andrew

We investigate the influence of B 4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization nearmore » Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.« less

Chemistry of vinylidene complexes. XXIV. A new μ-vinylidene complex containing RePt core, and platinum-bound carbonyl ligand. Spectroscopic, structural and electrochemical study

NASA Astrophysics Data System (ADS)

Verpekin, Victor V.; Vasiliev, Alexander D.; Kondrasenko, Alexander A.; Burmakina, Galina V.; Chudin, Oleg S.; Pavlenko, Nina I.; Zimonin, Dmitry V.; Rubaylo, Anatoly I.

2018-07-01

The novel heterobinuclear μ-vinylidene complex [Cp(CO)2Re(μ-C=CHPh)Pt(PPh3)(CO)] (1) was isolated from the reaction mixture of [Cp(CO)2Re(μ-C=CHPh)Fe(CO)4] and Pt(PPh3)4 for the first time. Alternative high-yield synthetic approaches to 1 were developed including the reactions of [Cp(CO)2Re(μ-C=CHPh)Pt(PPh3)2] (2) with Co2(CO)8 and Rh(acac)(CO)2. The complex was characterized by IR and 1H, 13C and 31P NMR spectroscopy, a molecular structure of 1 was determined by X-ray diffraction analysis. The electrochemical behavior of the new complex was studied by cyclic voltammetry at platinum or glassed carbon electrodes and by dc polarography at a dropping mercury electrode.

The haloarchaeal MCM proteins: bioinformatic analysis and targeted mutagenesis of the β7-β8 and β9-β10 hairpin loops and conserved zinc binding domain cysteines

PubMed Central

Kristensen, Tatjana P.; Maria Cherian, Reeja; Gray, Fiona C.; MacNeill, Stuart A.

2014-01-01

The hexameric MCM complex is the catalytic core of the replicative helicase in eukaryotic and archaeal cells. Here we describe the first in vivo analysis of archaeal MCM protein structure and function relationships using the genetically tractable haloarchaeon Haloferax volcanii as a model system. Hfx. volcanii encodes a single MCM protein that is part of the previously identified core group of haloarchaeal MCM proteins. Three structural features of the N-terminal domain of the Hfx. volcanii MCM protein were targeted for mutagenesis: the β7-β8 and β9-β10 β-hairpin loops and putative zinc binding domain. Five strains carrying single point mutations in the β7-β8 β-hairpin loop were constructed, none of which displayed impaired cell growth under normal conditions or when treated with the DNA damaging agent mitomycin C. However, short sequence deletions within the β7-β8 β-hairpin were not tolerated and neither was replacement of the highly conserved residue glutamate 187 with alanine. Six strains carrying paired alanine substitutions within the β9-β10 β-hairpin loop were constructed, leading to the conclusion that no individual amino acid within that hairpin loop is absolutely required for MCM function, although one of the mutant strains displays greatly enhanced sensitivity to mitomycin C. Deletions of two or four amino acids from the β9-β10 β-hairpin were tolerated but mutants carrying larger deletions were inviable. Similarly, it was not possible to construct mutants in which any of the conserved zinc binding cysteines was replaced with alanine, underlining the likely importance of zinc binding for MCM function. The results of these studies demonstrate the feasibility of using Hfx. volcanii as a model system for reverse genetic analysis of archaeal MCM protein function and provide important confirmation of the in vivo importance of conserved structural features identified by previous bioinformatic, biochemical and structural studies. PMID:24723920

Variable White Matter Atrophy and Intellectual Development in a Family With X-linked Creatine Transporter Deficiency Despite Genotypic Homogeneity.

PubMed

Heussinger, Nicole; Saake, Marc; Mennecke, Angelika; Dörr, Helmuth-Günther; Trollmann, Regina

2017-02-01

The X-linked creatine transporter deficiency (CRTD) caused by an SLC6A8 mutation represents the second most common cause of X-linked intellectual disability. The clinical phenotype ranges from mild to severe intellectual disability, epilepsy, short stature, poor language skills, and autism spectrum disorders. The objective of this study was to investigate phenotypic variability in the context of genotype, cerebral creatine concentration, and volumetric analysis in a family with CRTD. The clinical phenotype and manifestations of epilepsy were assessed in a Caucasian family with CRTD. DNA sequencing and creatine metabolism analysis confirmed the diagnosis. Cerebral magnetic resonance imaging (cMRI) with voxel-based morphometry and magnetic resonance spectroscopy was performed in all family members. An SLC6A8 missense mutation (c.1169C>T; p.Pro390Leu, exon 8) was detected in four of five individuals. Both male siblings were hemizygous, the mother and the affected sister heterozygous for the mutation. Structural cMRI was normal, whereas voxel-based morphometry analysis showed reduced white matter volume below the first percentile of the reference population of 290 subjects in the more severely affected boy compared with family members and controls. Normalized creatine concentration differed significantly between the individuals (P < 0.005). There is a broad phenotypic variability in CRTD even in family members with the same mutation. Differences in mental development could be related to atrophy of the subcortical white matter. Copyright © 2016 Elsevier Inc. All rights reserved.

Water-Solubilized, Cap-Stabilized, Helical Polyalanines: Calibration Standards for NMR and CD Analyses

PubMed Central

Heitmann, Björn; Job, Gabriel E.; Kennedy, Robert J.; Walker, Sharon M.; Kemp, Daniel S.

2006-01-01

NMR and CD studies are reported for two length series of solubilized, spaced, highly helical polyalanines that are N-capped by the optimal helix stabilizer βAsp-Hel and C-capped by β-aminoalanine beta and that are studied in water at 2 °C, pH 1–8. NMR analysis yields a structural characterization of the peptide AcβAspHelAla8betaNH2 and selected members of one βAspHelAlanbeta series. At pH > 4.5 the βAspHel cap provides a preorganized triad of carboxylate anion and two amide residues that is complementary to the helical polyalanine N-terminus. The C-terminal β-aminoalanine assumes a helix-stabilizing conformation consistent with literature precedents. H(N)CO NMR experiments applied to capped, uniformly 13C- and 15N-labeled Ala8 and Ala12 peptides define Alan hydrogen bonding signatures as α-helical without detectable 310 character. Relative NH→ND exchange rates yield site protection factors PFi that define uniquely high fractional helicities FH for the peptide Alan regions. These Alan calibration series, studied in water and lacking helix-stabilizing tertiary structure, yield the first 13C NMR chemical shifts, 3JHNHα coupling constants, and CD ellipticities [θMolar]λ,n characteristic of a fully helical alanine within an Alan context. CD data are used to assign parameters X and [θ]λ,∞, required for rigorous calculation of FH values from CD ellipticities. PMID:15701003

The structure and conformations of piracetam (2-oxo-1-pyrrolidineacetamide): Gas-phase electron diffraction and quantum chemical calculations

NASA Astrophysics Data System (ADS)

Ksenafontov, Denis N.; Moiseeva, Natalia F.; Khristenko, Lyudmila V.; Karasev, Nikolai M.; Shishkov, Igor F.; Vilkov, Lev V.

2010-12-01

The geometric structure of piracetam was studied by quantum chemical calculations (DFT and ab initio), gas electron diffraction (GED), and FTIR spectroscopy. Two stable mirror symmetric isomers of piracetam were found. The conformation of pyrrolidine ring is an envelope in which the C4 atom deviates from the ring plane, the angle between the planes (C3 sbnd C4 sbnd C5) and (C2 sbnd C3 sbnd C5) is 154.1°. The direction of the deviation is the same as that of the side acetamide group. The piracetam molecule is stabilized in the gas phase by an intramolecular hydrogen bond between the N9H 2 group and the oxygen O6, bonded to C2. The principal structural parameters ( re, Å and ∠e, degrees; uncertainties are 3 σLS values) were found to be: r(С3 sbnd С4) = 1.533(1), r(C4 sbnd C5) = 1.540(1), r(N1 sbnd C5) = 1.456(1), r(C2 sbnd C3) = 1.520(1), r(N1 sbnd C7) = 1.452(1), r(C7 sbnd C8) = 1.537(1), r(N1 sbnd C2) = 1.365(2), r(C8 sbnd N9) = 1.360(2), r(C2 dbnd O6) = 1.229(1), r(C8 dbnd O10) = 1.221(1), ∠C2 sbnd N1 sbnd C5 = 113.4(6), ∠N1 sbnd C2 sbnd C3 = 106.9(6), ∠N1 sbnd C7 sbnd C8 = 111.9(6), ∠C7 sbnd C8 sbnd N9 = 112.5(6), ∠N1 sbnd C2 sbnd O6 = 123.0(4), ∠C3 sbnd N1 sbnd C7 = 120.4(4), ∠C7 sbnd C8 sbnd O10 = 120.2(4), ∠C5 sbnd N1 sbnd C2 sbnd O6 = 170(6), ∠C3 sbnd C2 sbnd N1 sbnd C7 = 178(6), ∠C2 sbnd N1 sbnd C7 sbnd C8 = 84.2, ∠N1 sbnd C7 sbnd C8 sbnd O10 = 111.9.

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

Yang, Xi; Wang, Shanshan; Ghiviriga, Ion

A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt 3Au] 4(μ-N 3C 2C 6H 5) (1) and [PPhMe 2Au] 43C 2C 6H 5) (2) and {[PEt 3Au] 4[(μ-N 3C 2) 2-9,9-dihexyl-9H-fluorene]} n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysismore » reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. The degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

Structural analysis of nested neutralizing and non-neutralizing B cell epitopes on ricin toxin's enzymatic subunit.

PubMed

Rudolph, Michael J; Vance, David J; Cassidy, Michael S; Rong, Yinghui; Shoemaker, Charles B; Mantis, Nicholas J

2016-08-01

In this report, we describe the X-ray crystal structures of two single domain camelid antibodies (VH H), F5 and F8, each in complex with ricin toxin's enzymatic subunit (RTA). F5 has potent toxin-neutralizing activity, while F8 has weak neutralizing activity. F5 buried a total of 1760 Å(2) in complex with RTA and made contact with three prominent secondary structural elements: α-helix B (Residues 98-106), β-strand h (Residues 113-117), and the C-terminus of α-helix D (Residues 154-156). F8 buried 1103 Å(2) in complex with RTA that was centered primarily on β-strand h. As such, the structural epitope of F8 is essentially nested within that of F5. All three of the F5 complementarity determining regions CDRs were involved in RTA contact, whereas F8 interactions were almost entirely mediated by CDR3, which essentially formed a seventh β-strand within RTA's centrally located β-sheet. A comparison of the two structures reported here to several previously reported (RTA-VH H) structures identifies putative contact sites on RTA, particularly α-helix B, associated with potent toxin-neutralizing activity. This information has implications for rational design of RTA-based subunit vaccines for biodefense. Proteins 2016; 84:1162-1172. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Seismic soil structure interaction analysis for asymmetrical buildings supported on piled raft for the 2015 Nepal earthquake

NASA Astrophysics Data System (ADS)

Badry, Pallavi; Satyam, Neelima

2017-01-01

Seismic damage surveys and analyses conducted on modes of failure of structures during past earthquakes observed that the asymmetrical buildings show the most vulnerable effect throughout the course of failures (Wegner et al., 2009). Thus, all asymmetrical buildings significantly fails during the shaking events and it is really needed to focus on the accurate analysis of the building, including all possible accuracy in the analysis. Apart from superstructure geometry, the soil behavior during earthquake shaking plays a pivotal role in the building collapse (Chopra, 2012). Fixed base analysis where the soil is considered to be infinitely rigid cannot simulate the actual scenario of wave propagation during earthquakes and wave transfer mechanism in the superstructure (Wolf, 1985). This can be well explained in the soil structure interaction analysis, where the ground movement and structural movement can be considered with the equal rigor. In the present study the object oriented program has been developed in C++ to model the SSI system using the finite element methodology. In this attempt the seismic soil structure interaction analysis has been carried out for T, L and C types piled raft supported buildings in the recent 25th April 2015 Nepal earthquake (M = 7.8). The soil properties have been considered with the appropriate soil data from the Katmandu valley region. The effect of asymmetry of the building on the responses of the superstructure is compared with the author's research work. It has been studied/observed that the shape or geometry of the superstructure governs the response of the superstructure subjected to the same earthquake load.

Crystal Structures of Two Archaeal 8-Oxoguanine DNA Glycosylases Provide Structural Insight into Guanine/8-Oxoguanine Distinction

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

Faucher, Frédérick; Duclos, Stéphanie; Bandaru, Viswanath

Among the four DNA bases, guanine is particularly vulnerable to oxidative damage and the most common oxidative product, 7,8-dihydro-8-oxoguanine (8-oxoG), is the most prevalent lesion observed in DNA molecules. Fortunately, 8-oxoG is recognized and excised by the 8-oxoguanine DNA glycosylase (Ogg) of the base excision repair pathway. Ogg enzymes are divided into three separate families, namely, Ogg1, Ogg2, and archaeal GO glycosylase (AGOG). To date, structures of members of both Ogg1 and AGOG families are known but no structural information is available for members of Ogg2. Here we describe the first crystal structures of two archaeal Ogg2: Methanocaldococcus janischii Oggmore » and Sulfolobus solfataricus Ogg. A structural comparison with OGG1 and AGOG suggested that the C-terminal lysine of Ogg2 may play a key role in discriminating between guanine and 8-oxoG. This prediction was substantiated by measuring the glycosylase/lyase activity of a C-terminal deletion mutant of MjaOgg.« less

Zn(II) and Cd(II) coordination polymers with tri-tert-butoxysilanethiol and bipyridines. Synthesis, crystal structure and spectroscopy

NASA Astrophysics Data System (ADS)

Pladzyk, Agnieszka; Ponikiewski, Łukasz; Stanulewicz, Natalia; Hnatejko, Zbigniew

2013-12-01

Three new zinc(II) and cadmium(II) silanethiolate complexes [Zn{SSi(OtBu)3}2(μ-bpea)ṡCH3CN]n1, [Cd{SSi(OtBu)3}2(μ-bpea)ṡ2CHCl3]n2 and [Cd{SSi(OtBu)3}2(μ-bpey)ṡC7H8]n3 with two bypiridine derivatives, [bpea = 1,2-bis(4-pyridyl)ethane and bpey = 1,2-bis(4-pyridyl)ethylene] have been synthesized and structurally characterized by X-ray crystallography. Their structures and properties have also been established with elemental analysis, IR, TGA and photoluminescent studies. Complexes 1-3 exhibit one-dimensional (1D) chain structures in which [M{SSi(OtBu)3}2] (M = Zn, Cd) units are held together by bpea or bpey bridges, respectively. Complexes are stable up to 300 °C and display blue emissions.

Synthesis and structural study of 4-(2-chlorophenyl)-2-ethoxy-5,6,7,8,9,10-hexahydrocycloocta[B]pyridine-3-carbonitrile

NASA Astrophysics Data System (ADS)

Fathima, K. Saiadali; Vasumathi, M.; Anitha, K.

2016-05-01

The novel organic material C20H21ClN2O was synthesized by One-Pot synthesis method and the single crystals were grown by slow evaporation solution growth technique. The crystal structure was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R=0.039 for 2746 reflections. Crystal system of the grown crystal was found to be monoclinic with the space group P21/a and a=9.196(4) Å, b=13.449(4) Å, c=14.818(4) Å, β= 101.542(3)°, V=1795.6(11) Å3 and Z=4. In this crystal structure, cyclooctanone prefers to reside in a chair-boat conformation. The structure is stabilized by attractive molecular force such as CH/π interaction called hydrophobic interaction.

X-ray study of the hetero ring flexibility in 5,6-tri-, 5,6-tetra- and 5,6-penta-methylene-2,3,5,6-tetrahydro-1,3-oxazin-4-ones. The structures of 2-spiropentamethylene- cis-5,6-tetramethylene-2,3,5,6-tetrahydro-1,3-oxazin-4-one (I), 2-spiropentamethylene- cis-5,6-pentamethylene-2,3,5,6-tetrahydro-1,3-oxazin-4-one ( c-II) and 2-spiropentamethylene- trans-5,6-pentamethylene-2,3,5,6-tetrahydro-1,3-oxazin-4-one ( t-II)

NASA Astrophysics Data System (ADS)

Ribár, B.; Kapor, Á.; Kálmán, A.; Argay, Gy.; Fülöp, F.; Bernáth, G.

1989-01-01

The structures of the title compounds were established by X-ray crystallography by means of direct methods. Crystals of compound I (C 12H 19NO 2) are monoclinic, space group P2 1/ n, with a = 11.365(3), b = 10.343(4), c = 10.343(2) Å, β = 110.25(3)°, Z = 4 and Dc = 1.218 g cm -3. Crystals of compound c- II (C 13H 21NO 2) are monoclinic, space group C2/ c, with a = 20.830(8), b = 6.594(4), c = 17.944(8) Å, β = 95.83(2)°, Z = 8 and Dc = 1.209 g cm -3. Crystals of t- II (C 13H 21NO 2) are also monoclinic, space group P2 1/ n, with a = 14.268(4), b = 6.112(3), c = 14.041(7) Å, β = 93.63(3)°, Z = 4 and Dc = 1.210 g cm -3. The structures were refined to R = 0.059 for 1697 reflections of I, R = 0.052 for 1718 reflections of c- II, and R = 0.057 for 2178 reflections of t- II. The conformations of the 1,3-oxazin-4-one moieties in the title compounds were compared with those found earlier in related compounds. As shown by an analysis of the puckering parameters (D. Cremer and J.A. Pople, J. Am. Chem. Soc., 97 (1975) 1354), they cluster in a random distribution around the 1H 6 half-chair form. Marked deviation from this canonical form towards the 1E envelope was observed only under the influence of the cyclopentane ring.

The Effects of Random and Nonlinear Waves on Coastal and Offshore Structures

DTIC Science & Technology

1987-07-01

Barik and Paramasivam [2]. Dao and Penzien [3]. Leonard, et al. (4). and Tuali and Hudspeth [8). For a real sea state, the super- position of linear...34 Ocean Engng., Vol. 10, No. 5, 1983, p 303 312. [2] Barik , K. C. and V. Paramasivam, "Response Analysis of Offehore Struc- tures," J. Waterways Port

The crystal structure of calcite III

NASA Astrophysics Data System (ADS)

Smyth, Joseph R.; Ahrens, Thomas J.

The crystal structure of calcite III has been deduced from existing high pressure powder X-ray diffraction patterns, based on the assumption that it is a displacive modification of the calcite I structure. The structure is monoclinic with space group C2 and a Z of 6. There are two Ca and two C positions, and five O positions, and atom coordinates have been refined by distance-least-squares methods to give reasonable octahedral coordination for Ca and parallel, planar CO3 groups. Unit cell parameters refined from a published powder diffraction pattern at 4.1 GPa are: a = 8.746(8)Å b = 4.685(5)Å c = 8.275(8)Å and β= 94.4°. The structure has a calculated density of 2.949 Mg/m³ at 4.1 GPa which is less than that of aragonite at this pressure and consistent with early piston cylinder studies. This implies that calcite III is indeed a metastable intermediary between calcite I and aragonite.

Molecular structure, vibrational spectra, NBO analysis and molecular packing prediction of 3-nitroacetanilide by ab initio HF and density functional theory

NASA Astrophysics Data System (ADS)

Li, Xiao-Hong; Li, Tong-Wei; Ju, Wei-Wei; Yong, Yong-Liang; Zhang, Xian-Zhou

2014-01-01

Quantum chemical calculations of geometries and vibrational wavenumbers of 3-nitroacetanilide (C8H8N2O3) in the ground state were carried out by using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-31+G* basis set. The -311++G** basis set is also used for B3LYP level. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. Theoretical vibrational spectra of the title compound were interpreted by means of potential energies distributions (PEDs) using MOLVIB program. The theoretical spectrograms for IR spectra of the title compound have been constructed. The shortening of Csbnd H bond length and the elongation of Nsbnd H bond length suggest the existence of weak Csbnd H⋯O and Nsbnd H⋯O hydrogen bonds, which is confirmed by the natural bond orbital analysis. In addition, the crystal structure obtained by molecular mechanics belongs to the P21 space group, with lattice parameters Z = 4, a = 14.9989 Å, b = 4.0367 Å, c = 12.9913 Å, ρ = 0.998 g cm-3.

Alkali and alkaline earth metal salts of tetrazolone: structurally interesting and excellently thermostable.

PubMed

He, Piao; Wu, Le; Wu, Jin-Ting; Yin, Xin; Gozin, Michael; Zhang, Jian-Guo

2017-07-04

Tetrazolone (5-oxotetrazole) was synthesized by a moderate strategy through three steps (addition, cyclization and catalytic hydrogenation) avoiding the unstable intermediate diazonium, as reported during the previous preparation. Alkali and alkaline earth metal salts with lithium (1), sodium (2), potassium (3), rubidium (4) caesium (5), magnesium (6), calcium (7), strontium (8) and barium (9) were prepared and fully characterized using elemental analysis, IR and NMR spectroscopy, DSC and TG analysis. All metal salts were characterized via single-crystal X-ray diffraction. They crystallize in common space groups with high densities ranging from 1.479 (1) to 3.060 g cm -3 (5). Furthermore, the crystal structures of 7, 8 and 9 reveal interesting porous energetic coordination polymers with strong hydrogen bond interactions. All new salts have good thermal stabilities with decomposition temperature between 215.0 °C (4) and 328.2 °C (7), significantly higher than that of the reported nitrogen-rich salt neutral tetrazolone. The sensitivities towards impact and friction were tested using standard methods, and all the tetrazolone-based compounds investigated can be classified into insensitive. The flame test of these metal salts supports their potential use as perchlorate-free pyrotechnics or eco-friendly insensitive energetic materials.

Super RLuc8: A novel engineered Renilla luciferase with a red-shifted spectrum and stable light emission.

PubMed

Rahnama, Somaieh; Saffar, Behnaz; Kahrani, Zahra Fanaei; Nazari, Mahboobeh; Emamzadeh, Rahman

2017-01-01

Renilla luciferase is a bioluminescent enzyme which is broadly used as a reporter protein in molecular biosensors. In this study, a novel luciferase with desired light emission wavelength and thermostability is reported. The results indicated that the new luciferase, namely super RLuc8, had a red-shifted spectrum and showed stable light emission. Super RLuc8 showed a 10-fold (p-value=0.0084) increase in the thermostability at 37°C after 20min incubation, in comparison to the native enzyme. The optimum temperature of the mutant increased from 30 to 37°C. Molecular dynamics simulation analysis indicated that the increased thermostability was most probably caused by a better structural compactness and more local rigidity in the regions out of the emitter site. Copyright © 2016 Elsevier Inc. All rights reserved.

School Refusal Assessment Scale-Revised: Factorial Invariance and Latent Means Differences across Gender and Age in Spanish Children

PubMed Central

Gonzálvez, Carolina; Inglés, Cándido J.; Kearney, Christopher A.; Vicent, María; Sanmartín, Ricardo; García-Fernández, José M.

2016-01-01

The aim of this study was to analyze the factorial invariance and latent means differences of the Spanish version of the School Refusal Assessment Scale-Revised for Children (SRAS-R-C) in a sample of 1,078 students (50.8% boys) aged 8–11 years (M = 9.63, SD = 1.12). The results revealed that the proposed model in this study, with a structure of 18 items divided into four factors (Negative Affective, Social Aversion and/or Evaluation, To Pursue Attention and Tangible Reinforcements), was the best-fit model with a tetra-factorial structure, remaining invariant across gender and age. Analysis of latent means differences indicated that boys and 11-year-old students scored highest on the Tangible Reinforcements subscale compared with their 8- and 9-year-old peers. On the contrary, for the subscales of Social Aversion and/or Evaluation and to Pursue Attention, the differences were significant and higher in younger age groups compared to 11-year-olds. Appropriate indexes of reliability were obtained for SRAS-R-C subscales (0.70, 0.79, 0.87, and 0.72). Finally, the founded correlation coefficients of scores of the SRAS-R-C revealed a predictable pattern between school refusal and positive/negative affect and optimism/pessimism. PMID:28082938

Clathrate hydrates in the solar system

NASA Technical Reports Server (NTRS)

Miller, S. L.

1985-01-01

Clathrate hydrates are crystalline compounds in which an expanded ice lattice forms cages that contain gas molecules. There are two principal hydrate structures. Structure I, with a 12 A cubic unit cell, contains 46 water molecules and 8 cages of two types, giving an ideal formula (for CH4) of CH4.5.75H2O. The actual formula contains somewhat more water as the cages are not completely filled. Other examples that form Structure I hydrates are C2H6, C2H4, C2H2, CO2, SO2, OCS, Xe, H2S. Structure II, with a 17 A cubic unit cell, contains 136 water molecules, and 8 large and 16 small cages. The ideal formula for CHCl3 is CHCL3.17H2O. Other examples of Structure II hydrates include C3H8, C2H5Cl, acetone, and tetrahydrofuran. Small molecules such as Ar, Kr and probably N2 and O2 also form a Structure II hydrate. The small molecules occupy both the large and small cages, giving an ideal formula of Ar.5.67H2O. The conditions of pressure and temperature for hydrate formation are discussed.

Three Co(II) complexes with a sexidentate N2O4-donor bis-Schiff base ligand: Synthesis, crystal structures, DFT studies, urease inhibition and molecular docking studies

NASA Astrophysics Data System (ADS)

Wang, Hu; Zhang, Xia; Zhao, Yu; Zhang, Dongmei; Jin, Fan; Fan, Yuhua

2017-11-01

Three new N2O4-donor bis-Schiff base Co(II) complexes, Co(C36H34N2O8)·2CH3OH (1), Co(C28H34N2O8S2)·H2O (2) and Co(C40H36N4O8)·3CH3OH (3) with distorted octahedral six-coordinate Co(II) centers were synthesized and determined by single crystal X-ray analysis. The X-ray crystallography shows that the metal atoms of three complexes are all six-coordinate with two nitrogen atoms from Cdbnd N groups, two oxygen atoms from ether groups and two carboxylic oxygen atoms in the mono-ligand, forming a distorted octahedral geometry. Theoretical studies of the three complexes were carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-31G basis set. The DFT studies indicate that the calculation is in accordance with the experimental results. Moreover, inhibition of jack bean urease by Co(II) complexes 1-3 have also been investigated. At the same time, a docking analysis using a DOCK program was conducted to determine the probable binding mode by inserting the complexes into the active site of jack bean urease. The experimental values and docking simulation exhibited that the complex 3 showed strong inhibitory activity (IC50 = 16.43 ± 2.35 μM) and the structure-activity relationships were further discussed.

Molecular and crystal structure and the Hirshfeld surface analysis of 1-amino-1-deoxy-α-D-sorbopyranose and 1-amino-1-deoxy-α-D-psicopyranose ("D-sorbosamine" and "D-psicosamine") derivatives

NASA Astrophysics Data System (ADS)

Mossine, Valeri V.; Barnes, Charles L.; Mawhinney, Thomas P.

2018-05-01

Sorbosamine and psicosamine are the last two 1-amino-1-deoxy-hexuloses for which no structural data were available. We report on a13C NMR and a single crystal X-ray diffraction study of 1-deoxy-1-(N-methylphenylamino)-D-sorbose (1) and 1-deoxy-1-(N-methylphenylamino)-D-psicose (2). In solutions, both aminosugars are conformationally unstable and establish equilibria, with 90.7% α-pyranose, 3.8% α-furanose, 1.0% β-pyranose, 0.5% β-furanose, and 4.0% acyclic keto form for 1 and 32.4% α-furanose, 27.2% α-pyranose, 21.0% β-pyranose, 9.1% β-furanose, and 11.0% acyclic keto form for 2. X-ray diffraction data provided detailed structural information on 1 and 2 in the α-pyranose form. Both molecules adopt the 5C2 ring conformations, the bond distances and valence angles compare well with respective pyranose structures. All hydroxyl groups in crystal structures of both 1 and 2 participate in two-dimensional hydrogen bonding networks, the H-bonding pattern in 1 is dominated by co-crystallized water molecules. The Hirshfeld surface analysis revealed a significant contribution of non- or weakly polar interactions to the packing forces for both molecules, with crystal structure of 2 featuring short H⋯H contacts. Other structural features found in 2 are a significant planarity of the tertiary amino group (the pyramid heights are 0.127 Å in 2 vs 0.231 Å in 1), a concomitant non-involvement of the amine nitrogen in heteroatom contacts, and a unique anti-periplanar conformation around the C1sbnd C2 bond.

Structural basis for the neutralization and genotype specificity of hepatitis E virus.

PubMed

Tang, Xuhua; Yang, Chunyan; Gu, Ying; Song, Cuiling; Zhang, Xiao; Wang, Yingbin; Zhang, Jun; Hew, Choy Leong; Li, Shaowei; Xia, Ningshao; Sivaraman, J

2011-06-21

Hepatitis E virus (HEV) causes acute hepatitis in humans, predominantly by contamination of food and water, and is characterized by jaundice and flu-like aches and pains. To date, no vaccines are commercially available to prevent the disease caused by HEV. Previously, we showed that a monoclonal antibody, 8C11, specifically recognizes a neutralizing conformational epitope on HEV genotype I. The antibody 8C11 blocks the virus-like particle from binding to and penetrating the host cell. Here, we report the complex crystal structure of 8C11 Fab with HEV E2s(I) domain at 1.9 Å resolution. The 8C11 epitopes on E2s(I) were identified at Asp(496)-Thr(499), Val(510)-Leu(514), and Asn(573)-Arg(578). Mutations and cell-model assays identified Arg(512) as the most crucial residue for 8C11 interaction with and neutralization of HEV. Interestingly, 8C11 specifically neutralizes HEV genotype I, but not the other genotypes. Because HEV type I and IV are the most abundant genotypes, to understand this specificity further we determined the structure of E2s(IV) at 1.79 Å resolution and an E2s(IV) complex with 8C11 model was generated. The comparison between the 8C11 complexes with type I and IV revealed the key residues that distinguish these two genotypes. Of particular interest, the residue at amino acid position 497 at the 8C11 epitope region of E2s is distinct among these two genotypes. Swapping this residue from one genotype to another inversed the 8C11 reactivity, demonstrating the essential role played by amino acid 497 in the genotype recognition. These studies may lead to the development of antibody-based drugs for the specific treatment against HEV.

Ground Shock Effects from Accidental Explosions

DTIC Science & Technology

1976-11-01

1,200 P0 A = V P cp 8 Horizontal Dh = Dv tannin " 1 (cp/U)] Vh = Vv tan [sin" 1 (cp/U)] \\ - \\ tanfainŕ (cp/U)] For tan sin (c /U...explosive are not included in the present analysis . This effect will limit the credibility of the direct- induced ground shock predictions, but if the... analysis . Dr. D. R. Richmond of Lovelace Foundation provided data on human shock tolerances. 26 REFERENCES 1. "Structures to Resist the Effects of

BACKWARD ANGLE STRUCTURE IN THE 20Ne+28Si QUASIELASTIC SCATTERING

NASA Astrophysics Data System (ADS)

Sgouros, O.; Soukeras, V.; Pakou, A.; Patronis, N.; Zerva, K.; Keeley, N.; Strojek, I.; Trzcińska, A.; Piasecki, E.; Rusek, K.; Stiliaris, E.; Mazzocco, M.

2013-10-01

New data for the quasielastic scattering of 20Ne from a 28Si target at incident energies of 42.5 MeV and 52.3 MeV and for the 28Si(20Ne, 24Mg)24Mg, 28Si(20Ne, 16O)32S and 28Si(20Ne, 12C)36Ar transfer reactions at 52.3 MeV are reported. Oscillations are observed in the backward angle quasielastic scattering data at 52.3 MeV and the 28Si(20Ne, 12C)36Ar transfer cross-sections are of the same magnitude as those for single-α stripping. Coupled reaction channels (CRC) calculations are unable to describe either the quasielastic or the 28Si(20Ne, 12C)36Ar transfer data assuming a sequential α transfer process with α-particle form factors from the literature. The addition of direct 8Be cluster transfer can provide a reasonable description of both data sets, but only with much larger spectroscopic factors than suggested by simple structure calculations or the large 8Be emission thresholds of 20Ne, 28Si and 36Ar, suggesting that the observed structure is of resonance-like origin. An optical model analysis of the quasielastic scattering data is also reported.

Infrared and Raman spectroscopic characterization of the silicate mineral olmiite CaMn2+[SiO3(OH)](OH) - implications for the molecular structure

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Scholz, Ricardo; López, Andrés; Xi, Yunfei; Granja, Amanda; Žigovečki Gobac, Željka; Lima, Rosa Malena Fernandes

2013-12-01

We have studied the mineral olmiite CaMn[SiO3(OH)](OH) which forms a series with its calcium analogue poldervaartite CaCa[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is pure and contains only calcium and manganese in the formula. Thermogravimetric analysis proves the mineral decomposes at 502 °C with a mass loss of 8.8% compared with the theoretical mass loss of 8.737%. A strong Raman band at 853 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations. Two intense Raman bands observed at 3511 and 3550 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of olmiite.

Condensation of Macrocyclic Polyketides Produced by Penicillium sp. DRF2 with Mercaptopyruvate Represents a New Fungal Detoxification Pathway.

PubMed

de Castro, Marcos V; Ióca, Laura P; Williams, David E; Costa, Bruna Z; Mizuno, Carolina M; Santos, Mario F C; de Jesus, Karen; Ferreira, Éverton L F; Seleghim, Mirna H R; Sette, Lara D; Pereira Filho, Edenir R; Ferreira, Antonio G; Gonçalves, Natália S; Santos, Raquel A; Patrick, Brian O; Andersen, Raymond J; Berlinck, Roberto G S

2016-06-24

Application of a refined procedure of experimental design and chemometric analysis to improve the production of curvularin-related polyketides by a marine-derived Penicillium sp. DRF2 resulted in the isolation and identification of cyclothiocurvularins 6-8 and cyclosulfoxicurvularins 10 and 11, novel curvularins condensed with a mercaptolactate residue. Two additional new curvularins, 3 and 4, are also reported. The structures of the sulfur-bearing curvularins were unambiguously established by analysis of spectroscopic data and by X-ray diffraction analysis. Analysis of stable isotope feeding experiments with [U-(13)C3(15)N]-l-cysteine confirmed the presence of the 2-hydroxy-3-mercaptopropanoic acid residue in 6-8 and the oxidized sulfoxide in 10 and 11. Cyclothiocurvularins A (6) and B (7) are formed by spontaneous reaction between 10,11-dehydrocurvularin (2) and mercaptopyruvate (12) obtained by transamination of cysteine. High ratios of [U-(13)C3(15)N]-l-cysteine incorporation into cyclothiocurvularin B (7), the isolation of two diastereomers of cyclothiocurvularins, the lack of cytotoxicity of cyclothiocurvularin B (7) and its methyl ester (8), and the spontaneous formation of cyclothiocurvularins from 10,11-dehydrocurvularin and mercaptopyruvate provide evidence that the formation of cyclothiocurvularins may well correspond to a 10,11-dehydrocurvularin detoxification process by Penicillium sp. DRF2.

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

Faucher, Frédérick; Robey-Bond, Susan M.; Wallace, Susan S.

DNA is subject to a multitude of oxidative damages generated by oxidizing agents from metabolism and exogenous sources and by ionizing radiation. Guanine is particularly vulnerable to oxidation, and the most common oxidative product 8-oxoguanine (8-oxoG) is the most prevalent lesion observed in DNA molecules. 8-OxoG can form a normal Watson-Crick pair with cytosine (8-oxoG:C), but it can also form a stable Hoogsteen pair with adenine (8-oxoG:A), leading to a G:C {yields} T:A transversion after replication. Fortunately, 8-oxoG is recognized and excised by either of two DNA glycosylases of the base excision repair pathway: formamidopyrimidine-DNA glycosylase and 8-oxoguanine DNA glycosylasemore » (Ogg). While Clostridium acetobutylicum Ogg (CacOgg) DNA glycosylase can specifically recognize and remove 8-oxoG, it displays little preference for the base opposite the lesion, which is unusual for a member of the Ogg1 family. This work describes the crystal structures of CacOgg in its apo form and in complex with 8-oxo-2'-deoxyguanosine. A structural comparison between the apo form and the liganded form of the enzyme reveals a structural reorganization of the C-terminal domain upon binding of 8-oxoG, similar to that reported for human OGG1. A structural comparison of CacOgg with human OGG1, in complex with 8-oxoG containing DNA, provides a structural rationale for the lack of opposite base specificity displayed by CacOgg.« less

NMR structural studies of the ionizing radiation adduct 7-hydro-8-oxodeoxyguanosine (8-oxo-7H-dG) opposite deoxyadenosine in a DNA duplex. 8-oxo-7H-dG(syn)ter dot dA(anti) alignment at lesion site

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

Kouchakdjian, M.; Patel, D.J.; Bodepudi, V.

1991-02-05

Proton NMR studies are reported on the complementary d(C1-C2-A3-C4-T5-A6-oxo-G7-T8-C9-A10-C11-C12){center dot}d(G13-G14-T15-G16-A17-A18-T19-A20-G21-T22-G23-G24) dodecanucleotide duplex (designated 8-oxo-7H-dG{center dot}dA 12-mer), which contains a centrally located 7-hydro-8-oxodeoxyguanosine (8-oxo-7H-dG) residue, a group commonly found in DNA that has been exposed to ionizing radiation or oxidizing free radicals. From the NMR spectra it can be deduced that this moiety exists as two tautomers, or gives rise to two DNA conformations, that are in equilibrium and that exchange slowly. The present study focuses on the major component of the equilibrium that originates in the 6,8-dioxo tautomer of 8-oxo-7H-dG. The authors have assigned the exchangeable NH1, NH7, and NH{submore » 2}-2 base protons located on the Watson-Crick and Hoogsteen edges of 8-oxo-7H-dG7 in the 8-oxo-7H-dG{center dot}dA 12-mer duplex, using an analysis of one- and two-dimensional nuclear Overhauser enhancement (NOE) data in H{sub 2}O solution. They were able to detect a set of intra- and interstrand NOEs between protons (exchangeable and nonexchangeable) on adjacent residues in the d(A6-oxo-G7-T8){center dot}d(A17-A18-T19) trinucleotide segment centered about the lesion site that establishes stacking of the oxo-dG7(syn){center dot}dA(anti) pair between stable Watson-Crick dA6{center dot}dT19 and dT8{center dot}A17 base pairs with minimal perturbation of the helix. The structural studies demonstrate that 8-oxo-7H-dG(syn){center dot}dA(anti) forms a stable pair in the interior of the helix, providing a basis for the observed incorporation of dA opposite 8-oxo-7H-dG when readthrough occurs past this oxidized nucleoside base.« less

Comparison of headspace-oxylipin-volatilomes of some Eastern Himalayan mosses extracted by sample enrichment probe and analysed by gas chromatography-mass spectrometry.

PubMed

Mitra, Souvik; Burger, Barend V; Poddar-Sarkar, Mousumi

2017-03-01

Mosses have an inherent adaptability against different biotic and abiotic stresses. Oxylipins, the volatile metabolites derived from polyunsaturated fatty acids (PUFAs), play a key role in the chemical defence strategy of mosses. In the present study, a comparative survey of these compounds, including an investigation into their precursor fatty acids (FAs), was carried out for the first time on the mosses Brachymenium capitulatum (Mitt.) Paris, Hydrogonium consanguineum (Thwaites & Mitt.) Hilp., Barbula hastata Mitt., and Octoblepharum albidum Hedw. collected from the Eastern Himalayan Biodiversity hotspot. Their headspace volatiles were sampled using a high-efficiency sample enrichment probe (SEP) and were characterized by gas chromatography-mass spectrometric analysis. FAs from neutral lipid (NL) and phospholipid (PL) fractions were also evaluated. Analysis of the oxylipin volatilome revealed the generation of diverse metabolites from C 5 to C 18 , dominated by alkanes, alkenes, saturated and unsaturated alcohols, aldehydes, ketones and cyclic compounds, with pronounced structural variations. The C 6 and C 8 compounds dominated the total volatilome of all the samples. Analyses of FAs from membrane PL and storage NL highlighted the involvement of C 18 and C 20 PUFAs in oxylipin generation. The volatilome of each moss is characterized by a 'signature oxylipin mixture'. Quantitative differences in the C 6 and C 8 metabolites indicate their phylogenetic significance.

C8-structured carbon quantum dots: Synthesis, blue and green double luminescence, and origins of surface defects

NASA Astrophysics Data System (ADS)

Xifang, Chen; Wenxia, Zhang; Qianjin, Wang; Jiyang, Fan

Carbon quantum dots (CQDs) have attracted great attention in the past few years due to their low cytotoxicity, exploited various synthesis methods, unexampled abundance of raw materials on earth, and robust near-infrared to near-UV luminescence. Carbon nanoparticles have applications in biological labeling, delivery of drugs and biological molecules into cells, and light emitting diodes and lasing. CQDs generally exist as nanodiamonds or graphite quantum dots according to previous research reports. In this study, we report the first synthesis of the third-allotrope CQDs through carbonization of sucrose and study their luminescence properties. These CQDs have a body-centered cubic structure and each lattice point is composed of eight atoms which form a sub-cube (so called C8 crystal structure). High-resolution transmission electron microscopy and X-ray diffraction confirm the C8 structure of the synthesized carbon nanocrystallites with an average size of 2 nm. The C8 CQDs exhibit double-band luminescence with two peaks centered at around 432 and 520 nm. The study based on the photoluminescence, UV-Vis absorption, Fourier-transform infrared, and X-ray photoelectron spectroscopies reveals that the green emission originates from the C=O related surface defect.

The 1:1 co-crystal of 2-bromo-naphthalene-1,4-dione and 1,8-di-hydroxy-anthracene-9,10-dione: crystal structure and Hirshfeld surface analysis.

PubMed

Tonin, Marlon D L; Garden, Simon J; Jotani, Mukesh M; Wardell, Solange M S V; Wardell, James L; Tiekink, Edward R T

2017-05-01

The asymmetric unit of the title co-crystal, C 10 H 5 BrO 2 ·C 14 H 8 O 4 [systematic name: 2-bromo-1,4-di-hydro-naphthalene-1,4-dione-1,8-dihy-droxy-9,10-di-hydro-anthracene-9,10-dione (1/1)], features one mol-ecule of each coformer. The 2-bromo-naphtho-quinone mol-ecule is almost planar [r.m.s deviation of the 13 non-H atoms = 0.060 Å, with the maximum deviations of 0.093 (1) and 0.099 (1) Å being for the Br atom and a carbonyl-O atom, respectively]. The 1,8-di-hydroxy-anthra-quinone mol-ecule is planar (r.m.s. deviation for the 18 non-H atoms is 0.022 Å) and features two intra-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bonds. Dimeric aggregates of 1,8-di-hydroxy-anthra-quinone mol-ecules assemble through weak inter-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bonds. The mol-ecular packing comprises stacks of mol-ecules of 2-bromo-naphtho-quinone and dimeric assembles of 1,8-di-hydroxy-anthra-quinone with the shortest π-π contact within a stack of 3.5760 (9) Å occurring between the different rings of 2-bromo-naphtho-quinone mol-ecules. The analysis of the Hirshfeld surface reveals the importance of the inter-actions just indicated but, also the contribution of additional C-H⋯O contacts as well as C=O⋯π inter-actions to the mol-ecular packing.

Indole Alkaloids from Chaetomium globosum.

PubMed

Xu, Guo-Bo; He, Gu; Bai, Huan-Huan; Yang, Tao; Zhang, Guo-Lin; Wu, Lin-Wei; Li, Guo-You

2015-07-24

Two new indole alkaloids chaetocochin J (1) and chaetoglobinol A (8), along with chetomin (2), chetoseminudin A (3), cochliodinol (9), and semicochliodinol (10), were isolated from the rice culture of the fungus Chaetomium globosum. Their structures were elucidated by spectral analysis. Three new epipolythiodioxopiperazines, chaetocochins G-I (5-7), were identified by the combination of UPLC and mass spectrometric analysis. Chaetocochin I contained two sulfur bridges, one formed by three sulfur atoms between C-3 and C-11a, and the other formed by four sulfur atoms between C-3' and C-6'. Chaetocochin I was readily transformed into chetomin (2), chetoseminudin A (3), chaetocochin D (4), chaetocochin G (5), and chaetocochin H (6) by losing sulfur atoms. Compounds 1-3, and 8 exhibited antibacterial activities against Bacillus subtilis with MICs of 25, 0.78, 0.78, and 50 μg/mL, respectively, but not against Gram-negative bacterium (Escherichia coli). Compounds 2 and 8 were inactive against Candida albicans, Fusarium graminearum, Fusarium vasinfectum, Saccharomyces cerevisiae, and Aspergillus niger even at the high concentrations of 200 and 100 μg/mL, respectively. Compound 8 showed free radical scavenging capacity against the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical (ABTS(+•)), with IC50 values of 143.6 and 45.2 μM, respectively. The free radical scavenging capacity rates of compounds 1-3 on the DPPH and ABTS(+•) were less than 20% at the test concentrations (89.9-108.3 μM). The superoxide anion radical scavenging assay indicated that compounds 1-3, and 8 showed 14.8% (90.9 μM), 18.1% (90.9 μM), 51.5% (88.3 μM), and 30.4% (61.3 μM) superoxide anion radical scavenging capacity, respectively.

Novel molecular targets for kRAS downregulation: promoter G-quadruplexes

DTIC Science & Technology

2016-11-01

conditions, and described the structure as having mixed parallel/anti-parallel loops of lengths 2:8:10 in the 5’-3’ direction. Using selective small...and anti-parallel loop directionality of lengths 4:10:8 in the 5’–3’ direction, three tetrads stacked, and involving guanines in runs B, C, E, and F...a tri-stacked structure incorporating runs B, C, E and F with intervening loops of 2, 10, and 8 bases in the 5’–3’ direction. G = black circles, C

Rational Design, Synthesis and Evaluation of First Generation Inhibitors of the Giardia lamblia Fructose-1,6-biphosphate Aldolase

PubMed Central

Li, Zhimin; Liu, Zhengang; Cho, Dae Won; Zou, Jiwen; Gong, Maozhen; Breece, Robert M.; Galkin, Andrey; Li, Ling; Zhao, Hong; Maestas, Gabriel D.; Tierney, David L.; Herzberg, Osnat; Dunaway-Mariano, Debra; Mariano, Patrick S.

2011-01-01

Inhibitors of the Giardia lamblia fructose 1,6-bisphosphate aldolase (GlFBPA), which transforms fructose 1,6-bisphosphate (FBP) to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, were designed based on 3-hydroxy-2-pyridone and 1,2-dihydroxypyridine scaffolds that position two negatively charged tetrahedral groups for interaction with substrate phosphate binding residues, a hydrogen bond donor to the catalytic Asp83, and a Zn2+ binding group. The inhibition activities for the GlFBPA catalyzed reaction of FBP of the prepared alkyl phosphonate/phosphate substituted 3-hydroxy-2-pyridinones and a dihydroxypyridine were determined. The 3-hydroxy-2-pyridone inhibitor 8 was found to bind to GlFBPA with an affinity (Ki = 14 μM) that is comparable to that of FBP (Km = 2 μM) or its inert analog TBP (Ki = 1 μM). The X-ray structure of the GlFBPA-inhibitor 8 complex (2.3 Å) shows that 8 binds to the active site in the manner predicted by in silico docking with the exception of coordination with Zn2+. The observed distances and orientation of the pyridone ring O=C-C-OH relative to Zn2+ are not consistent with a strong interaction. To determine if Zn2+coordination occurs in the GlFBPA-inhibitor 8 complex in solution, EXAFS spectra were measured. A four coordinate geometry comprised of the three enzyme histidine ligands and an oxygen atom from the pyridone ring O=C-C-OH was indicated. Analysis of the Zn2+ coordination geometries in recently reported structures of class II FBPAs suggests that strong Zn2+ coordination is reserved for the enediolate-like transition state, accounting for minimal contribution of Zn2+ coordination to binding of 8 to GlFBPA. PMID:21333622

Titanium, aluminum and zinc complexes containing diamine-bis(benzotriazole phenolate) ligands: Synthesis, structural characterization and catalytic studies for ring-opening polymerization of ε-caprolactone

NASA Astrophysics Data System (ADS)

Liu, Zheng-Tang; Li, Chen-Yu; Chen, Jhy-Der; Liu, Wan-Ling; Tsai, Chen-Yen; Ko, Bao-Tsan

2017-04-01

Structurally diverse metal complexes bearing diamine-bis(benzotriazole phenolate) (DiBTP) ligands have been synthesized and fully characterized by single crystal X-ray crystallography. The reaction of Ti(OiPr)4 with C8MEADiBTP-H2 or C8BEADiBTP-H2 (1.0 mol equiv.) generated the monomeric titanium alkoxy complexes [(C8MEADiBTP)Ti(OiPr)2] (1) and [(C8BEADiBTP)Ti(OiPr)2] (2), respectively. Moreover, C8BEADiBTP-H2 reacted with 2.0 molar equiv. of AlMe3 to give the tetra-coordinated di-aluminum complex [(C8BEADiBTP)Al2Me4] (3). Zinc complex [(C8BEADiBTP)Zn2Et2] (4) could be obtained by the alkane elimination of ZnEt2 (2.0 equiv.) with C8BEADiBTP-H2 as the pro-ligand under similar synthetic methods in good yield. Single-crystal X-ray diffraction indicates that 3 is a bimetallic aluminum dimethyl complex with a tetradentate C8BEADiBTP moiety chelating two metal atoms, whereas complex 4 displays the dinuclear feature containing both tetra- and penta-coordinated zinc atoms bonded by one ONNON-pentadentate C8BEADiBTP ligand. Catalytic studies for ring-opening polymerization of ε-caprolactone of complex 1-4 were systematic explored; the comparative studies of such polymerization were also discussed.

Growth Oscillatory Zoning in Erythrite, Ideally Co3(AsO4)2·8H2O: Structural Variations in Vivianite-Group Minerals

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

Antao, Sytle M.; Dhaliwal, Inayat

The crystal structure of an oscillatory zoned erythrite sample from Aghbar mine, Bou Azzer, Morocco, was refined using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data, Rietveld refinement, space group C2/m, and Z = 2. The crystal contains two sets of oscillatory zones that appear to have developed during epitaxial growth. The unit-cell parameters obtained are a = 10.24799(3) Å, b = 13.42490(7) Å, c = 4.755885(8) Å, β = 105.1116(3)°, and V = 631.680(4) Å3. The empirical formula for erythrite, obtained with electron-probe micro-analysis (EPMA), is [Co2.78Zn0.11Ni0.07Fe0.04]Σ3.00(AsO4)2·8H2O. Erythrite belongs to the vivianite-type structure that contains M1O2(H2O)4 octahedra and M22O6(H2O)4 octahedralmore » dimers that are linked by TO4 (T5+ = As or P) tetrahedra to form complex layers parallel to the (010) plane. These layers are connected by hydrogen bonds. The average [6] = 2.122(1) Å and average [6] = 2.088(1) Å. With space group C2/m, there are two solid solutions: M3(AsO4)2·8H2O and M3(PO4)2·8H2O where M2+ = Mg, Fe, Co, Ni, or Zn. In these As- and P-series, using data from this study and from the literature, we find that their structural parameters evolve linearly with V and in a nearly parallel manner despite of the large difference in size between P5+ (0.170 Å) and As5+ (0.355 Å) cations. Average [4], [6], and [6] distances increase linearly with V. The average distance is affected by M atoms, whereas the average distance is unaffected because it contains shorter and stronger P–O bonds. Although As- and P-series occur naturally, there is no structural reason why similar V-series vivianite-group minerals do not occur naturally or cannot be synthesized.« less

Geometrically frustrated magnetic structures of the heavy-fermion compound CePdAl studied by powder neutron diffraction

NASA Astrophysics Data System (ADS)

Dönni, A.; Ehlers, G.; Maletta, H.; Fischer, P.; Kitazawa, H.; Zolliker, M.

1996-12-01

The heavy-fermion compound CePdAl with ZrNiAl-type crystal structure (hexagonal space group 0953-8984/8/50/043/img8) was investigated by powder neutron diffraction. The triangular coordination symmetry of magnetic Ce atoms on site 3f gives rise to geometrical frustration. CePdAl orders below 0953-8984/8/50/043/img9 with an incommensurate antiferromagnetic propagation vector 0953-8984/8/50/043/img10, and a longitudinal sine-wave (LSW) modulated spin arrangement. Magnetically ordered moments at Ce(1) and Ce(3) coexist with frustrated disordered moments at Ce(2). The experimentally determined magnetic structure is in agreement with group theoretical symmetry analysis considerations, calculated by the program MODY, which confirm that for Ce(2) an ordered magnetic moment parallel to the magnetically easy c-axis is forbidden by symmetry. Further low-temperature experiments give evidence for a second magnetic phase transition in CePdAl between 0.6 and 1.3 K. Magnetic structures of CePdAl are compared with those of the isostructural compound TbNiAl, where a non-zero ordered magnetic moment for the geometrically frustrated Tb(2) atoms is allowed by symmetry.

Sulfonamide-containing PTP 1B inhibitors: Docking studies, synthesis and model validation

NASA Astrophysics Data System (ADS)

Niu, Enli; Gan, Qiang; Chen, Xi; Feng, Changgen

2017-01-01

PTP 1B plays an important role in regulating insulin signaling pathway and is regarded as a valid target for curing diabetes and obesity. In this paper, two novel sulfonamide-containing PTP 1B inhibitors were designed, synthesized in mild condition, and characterized by FT-IR, 1H NMR, 13C NMR and elemental analysis. The single crystal of compounds 7 and 8 were obtained and their structures were determined by X-ray single crystal diffraction analysis. In addition, their inhibitory activity were predicted by genetic algorithm, and carried on in vitro enzyme activity test. Of which compound 8 showed good inhibitory activity, in consistent with docking studies.

Design Study of an 8 Meter Monolithic Mirror UV/Optical Space Telescope

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2008-01-01

This paper will review a recent NASA MSFC preliminary study that demonstrated the feasibility of launching a 6 to 8 meter class monolithic primary mirror telescope to Sun-Earth L2 using an Ares V. The study started with the unique capabilities of the Ares V vehicle and examined the feasibility of launching a large aperture low cost low risk telescope based on a conventional ground based glass primary mirror. Specific technical areas studied included optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; launch vehicle performance and trajectory; spacecraft including structure, propulsion, GN & C, avionics, power systems and reaction wheels; operations & servicing, mass budget and system cost. The study telescope was an on-axis three-mirror anastigmatic design with a fine steering mirror. The observatory has a 100 arc-minute (8.4 X 12 arc-minutes) of diffraction limited field of view at a wavelength les than 500 nm. The study assumed that the primary mirror would be fabricated from an existing Schott Zerodur residual VLT blank edged to 6.2 meters, 175 mm thick at the edge with a mass of 11,000 kg. The entire mass budget for the observatory including primary mirror, structure, light baffle tube, instruments, space craft, avionics, etc. is less than 40,000 kg - a 33% mass margin on the Ares V's 60,000 kg Sun-Earth L2 capability. An 8 meter class observatory would have a total mass of less than 60,000 kg of which the primary mirror is the largest contributor.

Structural and Biochemical Analyses Reveal the Mechanism of Glutathione S-Transferase Pi 1 Inhibition by the Anti-cancer Compound Piperlongumine.

PubMed

Harshbarger, Wayne; Gondi, Sudershan; Ficarro, Scott B; Hunter, John; Udayakumar, Durga; Gurbani, Deepak; Singer, William D; Liu, Yan; Li, Lianbo; Marto, Jarrod A; Westover, Kenneth D

2017-01-06

Glutathione S-transferase pi 1 (GSTP1) is frequently overexpressed in cancerous tumors and is a putative target of the plant compound piperlongumine (PL), which contains two reactive olefins and inhibits proliferation in cancer cells but not normal cells. PL exposure of cancer cells results in increased reactive oxygen species and decreased GSH. These data in tandem with other information led to the conclusion that PL inhibits GSTP1, which forms covalent bonds between GSH and various electrophilic compounds, through covalent adduct formation at the C7-C8 olefin of PL, whereas the C2-C3 olefin of PL was postulated to react with GSH. However, direct evidence for this mechanism has been lacking. To investigate, we solved the X-ray crystal structure of GSTP1 bound to PL and GSH at 1.1 Å resolution to rationalize previously reported structure activity relationship studies. Surprisingly, the structure showed that a hydrolysis product of PL (hPL) was conjugated to glutathione at the C7-C8 olefin, and this complex was bound to the active site of GSTP1; no covalent bond formation between hPL and GSTP1 was observed. Mass spectrometry (MS) analysis of the reactions between PL and GSTP1 confirmed that PL does not label GSTP1. Moreover, MS data also indicated that nucleophilic attack on PL at the C2-C3 olefin led to PL hydrolysis. Although hPL inhibits GSTP1 enzymatic activity in vitro, treatment of cells susceptible to PL with hPL did not have significant anti-proliferative effects, suggesting that hPL is not membrane-permeable. Altogether, our data suggest a model wherein PL is a prodrug whose intracellular hydrolysis initiates the formation of the hPL-GSH conjugate, which blocks the active site of and inhibits GSTP1 and thereby cancer cell proliferation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Structural and Biochemical Analyses Reveal the Mechanism of Glutathione S-Transferase Pi 1 Inhibition by the Anti-cancer Compound Piperlongumine*

PubMed Central

Harshbarger, Wayne; Gondi, Sudershan; Ficarro, Scott B.; Hunter, John; Udayakumar, Durga; Gurbani, Deepak; Singer, William D.; Liu, Yan; Li, Lianbo; Marto, Jarrod A.; Westover, Kenneth D.

2017-01-01

Glutathione S-transferase pi 1 (GSTP1) is frequently overexpressed in cancerous tumors and is a putative target of the plant compound piperlongumine (PL), which contains two reactive olefins and inhibits proliferation in cancer cells but not normal cells. PL exposure of cancer cells results in increased reactive oxygen species and decreased GSH. These data in tandem with other information led to the conclusion that PL inhibits GSTP1, which forms covalent bonds between GSH and various electrophilic compounds, through covalent adduct formation at the C7-C8 olefin of PL, whereas the C2-C3 olefin of PL was postulated to react with GSH. However, direct evidence for this mechanism has been lacking. To investigate, we solved the X-ray crystal structure of GSTP1 bound to PL and GSH at 1.1 Å resolution to rationalize previously reported structure activity relationship studies. Surprisingly, the structure showed that a hydrolysis product of PL (hPL) was conjugated to glutathione at the C7-C8 olefin, and this complex was bound to the active site of GSTP1; no covalent bond formation between hPL and GSTP1 was observed. Mass spectrometry (MS) analysis of the reactions between PL and GSTP1 confirmed that PL does not label GSTP1. Moreover, MS data also indicated that nucleophilic attack on PL at the C2-C3 olefin led to PL hydrolysis. Although hPL inhibits GSTP1 enzymatic activity in vitro, treatment of cells susceptible to PL with hPL did not have significant anti-proliferative effects, suggesting that hPL is not membrane-permeable. Altogether, our data suggest a model wherein PL is a prodrug whose intracellular hydrolysis initiates the formation of the hPL-GSH conjugate, which blocks the active site of and inhibits GSTP1 and thereby cancer cell proliferation. PMID:27872191

Atomistic study on the site preference and lattice vibration of Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} (T=Al and Ge)

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

Cheng, Hai-Xia; Wang, Xiao-Xu; Department of Materials Engineering, National Ping Tung University of Technology and Science, Ping-Tung 91201, Taiwan

The effects of the Y substitution for Gd on the structural stability and the site preference of intermetallics Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} (T=Al and Ge) are studied by using a series of interatomic pair potentials. The calculated results show Y can stabilize Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} with the tetragonal structure, and Y substitute for Gd with a strong preference for the 2b sites. The calculated lattice parameters are in good agreement with the experimental data. Furthermore, the total and partial phonon densities of states are evaluated for the Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} compounds withmore » the tetragonal structure. A qualitative analysis is carried out with the relevant potentials for the vibrational modes, which makes it possible to predict some properties related to lattice vibration. - Graphical abstract: The lattice cell of Gd{sub 3}Co{sub 29}T{sub 4}B{sub 10} consists of 92 atoms, or two Gd{sub 3}Co{sub 29}T{sub 4}B{sub 10} formula units, with fourteen distinct kinds of site. Rare-earth atoms occupy 2b and 4d sites, Co atoms occupy the Co1(2c), Co2(8i1), Co3(8i2), Co4(8i3), Co5(8j1), Co6(8j2) and Co7(16k), T atoms occupy the T(8i) sites, and B atoms occupy the B1(2c1), B2(2c2), B3(8i) and B4(8j) sites. - Highlights: • The application of the pair potentials obtained from lattice-inversion method. • The lattice vibrations for Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} (T=Ge and Al) are first evaluated. • The Y atoms should prefer the 2b site of Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} compounds. • The total and partial phonon densities of states are evaluated for the Gd{sub 3−x}Y{sub x}Co{sub 29}T{sub 4}B{sub 10} compounds with the tetragonal structure. • A qualitative analysis is carried out with the relevant potentials for the vibrational modes.« less

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

Davaasuren, Bambar; Dashjav, Enkhtsetseg; Kreiner, Guido

The carboferrates RE{sub 15}[Fe{sub 8}C{sub 25}] (RE=Dy, Ho) were prepared from mixtures of the elements by arc-melting followed with subsequent annealing at 1373 K. The crystal structures were determined from single crystal X-ray diffraction data and revealed an isotypic relationship to Er{sub 15}[Fe{sub 8}C{sub 25}] (hP48, P321). The main feature of the crystal structure is given by Fe{sub 6} cluster units characterized by covalent Fe–Fe bonding interactions. {sup 57}Fe Mössbauer spectra of Dy{sub 15}[Fe{sub 8}C{sub 25}] were fitted by three subspectra with relative spectral weights of about 3:3:2 which is in general agreement with the crystal structure. Below 50 K,more » an onset of magnetic hyperfine fields at the three iron sites is observed which is supposed to be caused by dipolar fields arising from neighboring, slowly relaxing Dy magnetic moments. - Graphical abstract: Fe{sub 6}-cluster in the crystal structure of RE{sub 15}[Fe{sub 8}C{sub 25}], RE=Dy, Ho. - Highlights: • New carboferrates RE{sub 15}[Fe{sub 8}C{sub 25}] with RE=Dy, Ho have been synthesized. • The crystal structures were refined using single crystal X-ray data. • An orientational relationship between Fe{sub 6}-clusters and Fe in γ-Fe is outlined. • {sup 57}Fe Mössbauer spectra are in agreement with structural data from X-rays. • Magnetic hyperfine fields below 50 K are explained by dipolar fields from Dy atoms.« less

Terpenoids and norlignans from Metasequoia glyptostroboides.

PubMed

Dong, Liao-Bin; He, Juan; Wang, Yuan-Yuan; Wu, Xing-De; Deng, Xu; Pan, Zheng-Hong; Xu, Gang; Peng, Li-Yan; Zhao, Yu; Li, Yan; Gong, Xun; Zhao, Qin-Shi

2011-02-25

Four new terpenoids, metaseglyptorin A (1), metasequoic acid C (2), 12α-hydroxy-8,15-isopimaradien-18-oic acid (3), and (-)-acora-2,4(14),8-trien-15-oic acid (4), and three new norlignans, metasequirins D-F (5-7), were isolated from Metasequoia glyptostroboides, together with 15 known compounds. Structures of the new compounds were determined by analysis of their spectroscopic data, and the absolute configuration of 7 was established by the modified Mosher method. All of the compounds were evaluated for cytotoxicity against five human tumor cell lines.

Genome-Wide Divergence and Linkage Disequilibrium Analyses for Capsicum baccatum Revealed by Genome-Anchored Single Nucleotide Polymorphisms

PubMed Central

Nimmakayala, Padma; Abburi, Venkata L.; Saminathan, Thangasamy; Almeida, Aldo; Davenport, Brittany; Davidson, Joshua; Reddy, C. V. Chandra Mohan; Hankins, Gerald; Ebert, Andreas; Choi, Doil; Stommel, John; Reddy, Umesh K.

2016-01-01

Principal component analysis (PCA) with 36,621 polymorphic genome-anchored single nucleotide polymorphisms (SNPs) identified collectively for Capsicum annuum and Capsicum baccatum was used to characterize population structure and species domestication of these two important incompatible cultivated pepper species. Estimated mean nucleotide diversity (π) and Tajima's D across various chromosomes revealed biased distribution toward negative values on all chromosomes (except for chromosome 4) in cultivated C. baccatum, indicating a population bottleneck during domestication of C. baccatum. In contrast, C. annuum chromosomes showed positive π and Tajima's D on all chromosomes except chromosome 8, which may be because of domestication at multiple sites contributing to wider genetic diversity. For C. baccatum, 13,129 SNPs were available, with minor allele frequency (MAF) ≥0.05; PCA of the SNPs revealed 283 C. baccatum accessions grouped into 3 distinct clusters, for strong population structure. The fixation index (FST) between domesticated C. annuum and C. baccatum was 0.78, which indicates genome-wide divergence. We conducted extensive linkage disequilibrium (LD) analysis of C. baccatum var. pendulum cultivars on all adjacent SNP pairs within a chromosome to identify regions of high and low LD interspersed with a genome-wide average LD block size of 99.1 kb. We characterized 1742 haplotypes containing 4420 SNPs (range 9–2 SNPs per haplotype). Genome-wide association study (GWAS) of peduncle length, a trait that differentiates wild and domesticated C. baccatum types, revealed 36 significantly associated genome-wide SNPs. Population structure, identity by state (IBS) and LD patterns across the genome will be of potential use for future GWAS of economically important traits in C. baccatum peppers. PMID:27857720

Genome-Wide Divergence and Linkage Disequilibrium Analyses for Capsicum baccatum Revealed by Genome-Anchored Single Nucleotide Polymorphisms.

PubMed

Nimmakayala, Padma; Abburi, Venkata L; Saminathan, Thangasamy; Almeida, Aldo; Davenport, Brittany; Davidson, Joshua; Reddy, C V Chandra Mohan; Hankins, Gerald; Ebert, Andreas; Choi, Doil; Stommel, John; Reddy, Umesh K

2016-01-01

Principal component analysis (PCA) with 36,621 polymorphic genome-anchored single nucleotide polymorphisms (SNPs) identified collectively for Capsicum annuum and Capsicum baccatum was used to characterize population structure and species domestication of these two important incompatible cultivated pepper species. Estimated mean nucleotide diversity (π) and Tajima's D across various chromosomes revealed biased distribution toward negative values on all chromosomes (except for chromosome 4) in cultivated C. baccatum , indicating a population bottleneck during domestication of C. baccatum . In contrast, C. annuum chromosomes showed positive π and Tajima's D on all chromosomes except chromosome 8, which may be because of domestication at multiple sites contributing to wider genetic diversity. For C. baccatum , 13,129 SNPs were available, with minor allele frequency (MAF) ≥0.05; PCA of the SNPs revealed 283 C. baccatum accessions grouped into 3 distinct clusters, for strong population structure. The fixation index ( F ST ) between domesticated C. annuum and C. baccatum was 0.78, which indicates genome-wide divergence. We conducted extensive linkage disequilibrium (LD) analysis of C. baccatum var. pendulum cultivars on all adjacent SNP pairs within a chromosome to identify regions of high and low LD interspersed with a genome-wide average LD block size of 99.1 kb. We characterized 1742 haplotypes containing 4420 SNPs (range 9-2 SNPs per haplotype). Genome-wide association study (GWAS) of peduncle length, a trait that differentiates wild and domesticated C. baccatum types, revealed 36 significantly associated genome-wide SNPs. Population structure, identity by state (IBS) and LD patterns across the genome will be of potential use for future GWAS of economically important traits in C. baccatum peppers.

Detecting novel SNPs and breed-specific haplotypes at calpastatin gene in Iranian fat- and thin-tailed sheep breeds and their effects on protein structure.

PubMed

Aali, Mohsen; Moradi-Shahrbabak, Mohammad; Moradi-Shahrbabak, Hosein; Sadeghi, Mostafa

2014-03-01

Calpastatin has been introduced as a potential candidate gene for growth and meat quality traits. In this study, genetic variability was investigated in the exon 6 and its intron boundaries of ovine CAST gene by PCR-SSCP analysis and DNA sequencing. Also a protein sequence and structural analysis were performed to predict the possible impact of amino acid substitutions on physicochemical properties and structure of the CAST protein. A total of 487 animals belonging to four ancient Iranian sheep breeds with different fat metabolisms, Lori-Bakhtiari and Chall (fat-tailed), Zel-Atabay cross-bred (medium fat-tailed) and Zel (thin-tailed), were analyzed. Eight unique SSCP patterns, representing eight different sequences or haplotypes, CAST-1, CAST-2 and CAST-6 to CAST-11, were identified. Haplotypes CAST-1 and CAST-2 were most common with frequency of 0.365 and 0.295. The novel haplotype CAST-8 had considerable frequency in Iranian sheep breeds (0.129). All the consensus sequences showed 98-99%, 94-98%, 92-93% and 82-83% similarity to the published ovine, caprine, bovine and porcine CAST locus sequences, respectively. Sequence analysis revealed four SNPs in intron 5 (C24T, G62A, G65T and T69-) and three SNPs in exon 6 (c.197A>T, c.282G>T and c.296C>G). All three SNPs in exon 6 were missense mutations which would result in p.Gln 66 Leu, p.Glu 94 Asp and p.Pro 99 Arg substitutions, respectively, in CAST protein. All three amino acid substitutions affected the physicochemical properties of ovine CAST protein including hydrophobicity, amphiphilicity and net charge and subsequently might influence its structure and effect on the activity of Ca2+ channels; hence, they might regulate calpain activity and afterwards meat tenderness and growth rate. The Lori-Bakhtiari population showed the highest heterozygosity in the ovine CAST locus (0.802). Frequency difference of haplotypes CAST-10 and CAST-8 between Lori-Bakhtiari (fat-tailed) and Zel (thin-tailed) breeds was highly significant (P<0.001), indicating that these two haplotypes might be breed-specific haplotypes that distinguish between fat-tailed and thin-tailed sheep breeds. Copyright © 2013 Elsevier B.V. All rights reserved.

Otolith shape analysis for stock discrimination of two Collichthys genus croaker (Pieces: Sciaenidae,) from the northern Chinese coast

NASA Astrophysics Data System (ADS)

Zhao, Bo; Liu, Jinhu; Song, Junjie; Cao, Liang; Dou, Shuozeng

2017-08-01

The otolith morphology of two croaker species (Collichthys lucidus and Collichthys niveatus) from three areas (Liaodong Bay, LD; Huanghe (Yellow) River estuary, HRE; Jiaozhou Bay, JZ) along the northern Chinese coast were investigated for species identification and stock discrimination. The otolith contour shape described by elliptic Fourier coefficients (EFC) were analysed using principal components analysis (PCA) and stepwise canonical discriminant analysis (CDA) to identify species and stocks. The two species were well differentiated, with an overall classification success rate of 97.8%. And variations in the otolith shapes were significant enough to discriminate among the three geographical samples of C. lucidus (67.7%) or C. niveatus (65.2%). Relatively high mis-assignment occurred between the geographically adjacent LD and HRE samples, which implied that individual mixing may exist between the two samples. This study yielded information complementary to that derived from genetic studies and provided information for assessing the stock structure of C. lucidus and C. niveatus in the Bohai Sea and the Yellow Sea.

Studies of the metastable decay of met-cars. The vanadium and niobium systems

NASA Astrophysics Data System (ADS)

Purnell, J.; Wei, S.; Castleman, A. W., Jr.

1994-10-01

The decay fractions and metastable decomposition channels were measured for V(m)C(n)(+) and Nb(m)C(n)(+) clusters using a reflectron time-of-flight mass spectrometer. These measurements for the V(m)C(n)(+) clusters reveal stable (8, 12) and (8, 13) met-car species. However, under the present experimental conditions, the Nb(m)C(n)(+) clusters display dominantly cubic structures, but the decay fraction and metastable decomposition measurements also show the presence of a stable (8, 12) species in the parent cluster spectrum. This evidence indicates that cubic structures and met-cars are being formed simultaneously for the niobium system.

Role for Tyrosine Phosphorylation of A-kinase Anchoring Protein 8 (AKAP8) in Its Dissociation from Chromatin and the Nuclear Matrix.

PubMed

Kubota, Sho; Morii, Mariko; Yuki, Ryuzaburo; Yamaguchi, Noritaka; Yamaguchi, Hiromi; Aoyama, Kazumasa; Kuga, Takahisa; Tomonaga, Takeshi; Yamaguchi, Naoto

2015-04-24

Protein-tyrosine phosphorylation regulates a wide variety of cellular processes at the plasma membrane. Recently, we showed that nuclear tyrosine kinases induce global nuclear structure changes, which we called chromatin structural changes. However, the mechanisms are not fully understood. In this study we identify protein kinase A anchoring protein 8 (AKAP8/AKAP95), which associates with chromatin and the nuclear matrix, as a nuclear tyrosine-phosphorylated protein. Tyrosine phosphorylation of AKAP8 is induced by several tyrosine kinases, such as Src, Fyn, and c-Abl but not Syk. Nucleus-targeted Lyn and c-Src strongly dissociate AKAP8 from chromatin and the nuclear matrix in a kinase activity-dependent manner. The levels of tyrosine phosphorylation of AKAP8 are decreased by substitution of multiple tyrosine residues on AKAP8 into phenylalanine. Importantly, the phenylalanine mutations of AKAP8 inhibit its dissociation from nuclear structures, suggesting that the association/dissociation of AKAP8 with/from nuclear structures is regulated by its tyrosine phosphorylation. Furthermore, the phenylalanine mutations of AKAP8 suppress the levels of nuclear tyrosine kinase-induced chromatin structural changes. In contrast, AKAP8 knockdown increases the levels of chromatin structural changes. Intriguingly, stimulation with hydrogen peroxide induces chromatin structural changes accompanied by the dissociation of AKAP8 from nuclear structures. These results suggest that AKAP8 is involved in the regulation of chromatin structural changes through nuclear tyrosine phosphorylation. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Ergot alkaloids produced by submerged cultures of Claviceps zizaniae.

PubMed

Kantorová, Michaela; Kolínská, Renata; Pazoutová, Sylvie; Honzátko, Ales; Havlícek, Vladimír; Flieger, Miroslav

2002-07-01

Two ergopeptine alkaloids, alpha-ergocryptine (1) and its C(8) epimer alpha-ergocryptinine, have been isolated from the mycelium and fermentation broth of submerged cultures of Claviceps zizaniae CCM 8240. The structure of 1 was determined by HPLC/positive ion APCI MS and NMR analysis. Alkaloid concentrations of 10 microg/mL in 14-day-old fermentation broth and 1 mg/g of dry mycelium mass were found. These results are of considerable biotechnological interest since these were the only detectable alkaloids produced. Toxicity of naturally occurring sclerotia of C. zizaniae cannot be excluded.

Consistent Structural Integrity and Efficient Certification with Analysis. Volume 2: Detailed Report on Innovative Research Developed, Applied, and Commercially Available

DTIC Science & Technology

2005-05-01

RESULTS ................................................................................................................49 5.3.1 Phase I Test Data...Ins 3 2.2a Wrinkling failure test article 7 2.2b Test results for a) Set A “0° core”, and b) Set B “90° core” 7 2.2c Test ... results for c) Set E “Isotropic (Foam) Core” 8 2.3 P = T because test data not yet reanalyzed with established CFs 9 2.4 P and T are now different

New structure type in the mixed-valent compound YbCu4Ga8.

PubMed

Subbarao, Udumula; Gutmann, Matthias J; Peter, Sebastian C

2013-02-18

The new compound YbCu(4)Ga(8) was obtained as large single crystals in high yield from reactions run in liquid gallium. Preliminary investigations suggest that YbCu(4)Ga(8) crystallizes in the CeMn(4)Al(8) structure type, tetragonal space group I4/mmm, and lattice constants are a = b = 8.6529(4) Å and c = 5.3976(11) Å. However, a detailed single-crystal XRD revealed a tripling of the c axis and crystallizing in a new structure type with lattice constants of a = b = 8.6529(4) Å and c = 15.465(1) Å. The structural model was further confirmed by neutron diffraction measurements on high-quality single crystal. The crystal structure of YbCu(4)Ga(8) is composed of pseudo-Frank-Kasper cages occupying one ytterbium atom in each ring which are shared through the corner along the ab plane, resulting in a three-dimensional network. The magnetic susceptibility of YbCu(4)Ga(8) investigated in the temperature range 2-300 K showed Curie-Weiss law behavior above 100 K, and the experimentally measured magnetic moment indicates mixed-valent ytterbium. Electrical resistivity measurements show the metallic nature of the compound. At low temperatures, variation of ρ as a function of T indicates a possible Fermi-liquid state at low temperatures.

Potential and kinetic energetic analysis of phonon modes in varied molecular solids

NASA Astrophysics Data System (ADS)

Kraczek, Brent

2015-03-01

We calculate partitioned kinetic and potential energies of the phonon modes in molecular solids to illuminate the dynamical behavior of the constituent molecules. This enables analysis of the relationship between the characteristics of sets of phonon modes, molecular structure and chemical reactivity by partitioning the kinetic energy into the translational, rotational and vibrational motions of groups of atoms (including molecules), and the potential energy into the energy contained within interatomic interactions. We consider three solids of differing size and rigidity: naphthalene (C1 0 H6), nitromethane (CH3NO2)andα-HMX(C4H8N8O8). Naphthalene and nitromethane mostly act in the semi-rigid manner often expected in molecular solids. HMX exhibits behavior that is significantly less-rigid. While there are definite correlations between the kinetic and potential energetic analyses, there are also differences, particularly in the excitation of chemical bonds by low-frequency lattice modes. This suggests that in many cases computational and experimental methods dependent on atomic displacements may not identify phonon modes active in chemical reactivity.

Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers

DOE PAGES

Wang, Hao; Dong, Xinglong; Lin, Junzhong; ...

2018-05-01

As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr 6O 4(OH) 4(bptc) 3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr 6O 4(OH) 8(H 2O) 4(abtc) 2, ismore » capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.« less

Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers

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

Wang, Hao; Dong, Xinglong; Lin, Junzhong

As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr 6O 4(OH) 4(bptc) 3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr 6O 4(OH) 8(H 2O) 4(abtc) 2, ismore » capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.« less

Superspace description of wagnerite-group minerals (Mg,Fe,Mn)2(PO4)(F,OH)

PubMed Central

Lazic, Biljana; Armbruster, Thomas; Chopin, Christian; Grew, Edward S.; Baronnet, Alain; Palatinus, Lukas

2014-01-01

Reinvestigation of more than 40 samples of minerals belonging to the wagnerite group (Mg, Fe, Mn)2(PO4)(F,OH) from diverse geological environments worldwide, using single-crystal X-ray diffraction analysis, showed that most crystals have incommensurate structures and, as such, are not adequately described with known polytype models (2b), (3b), (5b), (7b) and (9b). Therefore, we present here a unified superspace model for the structural description of periodically and aperiodically modulated wagnerite with the (3+1)-dimensional superspace group C2/c(0β0)s0 based on the average triplite structure with cell parameters a ≃ 12.8, b ≃ 6.4, c ≃ 9.6 Å, β ≃ 117° and the modulation vectors q = β b*. The superspace approach provides a way of simple modelling of the positional and occupational modulation of Mg/Fe and F/OH in wagnerite. This allows direct comparison of crystal properties. PMID:24675594

Interface electronic structure and morphology of 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on Au film

NASA Astrophysics Data System (ADS)

Wang, Shitan; Niu, Dongmei; Lyu, Lu; Huang, Yingbao; Wei, Xuhui; Wang, Can; Xie, Haipeng; Gao, Yongli

2017-09-01

The interfacial electronic structure and morphology of 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene(C8-BTBT) on polycrystalline Au film was investigated with photoemission spectroscopy (PES), atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD). The transport barriers of holes and electrons at the interface are 1.72 eV and 2.12 eV, respectively, from the UPS measurement. There is no chemical reaction of C8-BTBT with Au from the XPS investigation of core levels Au 4f, C 1s and S 2p. The upmost molecules adopt a standing up configuration deduced from the diffraction peaks in GIXRD and the step height in AFM. Increasing order of the upright orientation of C8-BTBT molecules with film growth result in decreasing work function of the C8-BTBT thin film by forming an outward pointing dipole layer with the ordered end Csbnd H bonds.

Synthesis and characterisation of new types of side chain cholesteryl polymers.

PubMed

Wang, Bin; Du, Haiyan; Zhang, Junhua

2011-01-01

A series of cholesterol derivatives have been synthesised via the alkylation reaction of the 3-hydroxyl group with the aliphatic bromide compounds with different chain lengths, namely 3β-alkyloxy-cholesterol. The double bond between the C5 and C6 positions in these cholesterol derivatives was oxidised into epoxy, followed by an epoxy-ring-opening reaction with the treatment with acrylic acid, resulting in a series of 3β-alkyloxy-5α-hydroxy-6β-acryloyloxycholesterol, C(n)OCh (n=1, 2, 4, 6, 8, 10, 12), The acrylate group is connected to the C6 position, which is confirmed by the single crystal structure analysis. The corresponding polymers, PC(n)OCh, were prepared via free radical polymerisation. The structure of monomers and the resulting polymers were characterised with nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). The thermal properties of PC(n)OCh were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). To determine the secondary structure of polymers, circular dichroism (CD) spectra were performed. It was found that not all monomers produce high-molecular-weight polymers because of steric hindrance. However, all polymers have a helical structure, which can be enhanced by increasing the alkoxy chain length. In addition, increasing the alkoxy chain length decreases the glass transition temperature and increases the decomposition temperature of the polymers. Copyright © 2010 Elsevier Inc. All rights reserved.

Scoparic acid A, a beta-glucuronidase inhibitor from Scoparia dulcis.

PubMed

Hayashi, T; Kawasaki, M; Okamura, K; Tamada, Y; Morita, N; Tezuka, Y; Kikuchi, T; Miwa, Y; Taga, T

1992-12-01

The 70% EtOH extract of Scoparia dulcis showed inhibitory activity against beta-glucuronidase from bovine liver. Bioassay-directed fractionation of the active extract led to the isolation of three labdane-type diterpene acids, scoparic acid A [1] [6-benzoyl-12-hydroxy-labda-8(17), 13-dien-18-oic acid], scoparic acid B [2] [6-benzoyl-14,15-dinor-13-oxo-8(17)-labden-18-oic acid], and scoparic acid C [3] [6-benzoyl-15-nor-14-oxo-8(17)-labden-18-oic acid], the structures of which were established by spectral means, including X-ray analysis. Scoparic acid A was found to be a potent beta-glucuronidase inhibitor.

Study on structural recovery of graphite irradiated with swift heavy ions at high temperature

NASA Astrophysics Data System (ADS)

Pellemoine, F.; Avilov, M.; Bender, M.; Ewing, R. C.; Fernandes, S.; Lang, M.; Li, W. X.; Mittig, W.; Schein, M.; Severin, D.; Tomut, M.; Trautmann, C.; Zhang, F. X.

2015-12-01

Thin graphite foils bombarded with an intense high-energy (8.6 MeV/u) gold beam reaching fluences up to 1 × 1015 ions/cm2 lead to swelling and electrical resistivity changes. As shown earlier, these effects are diminished with increasing irradiation temperature. The work reported here extends the investigation of beam induced changes of these samples by structural analysis using synchrotron X-ray diffraction and transmission electron microscope. A nearly complete recovery from swelling at irradiation temperatures above about 1500 °C is identified.

Synthesis and characterization of 3-acetoxy-2-methyl-N-(phenyl)benzamide and 3-acetoxy-2-methyl-N-(4- methylphenyl)benzamide

NASA Astrophysics Data System (ADS)

Kırca, Başak Koşar; Çakmak, Şükriye; Kütük, Halil; Odabaşoğlu, Mustafa; Büyükgüngör, Orhan

2018-01-01

This study treats about two successfully synthesized secondary amide compounds 3-Acetoxy-2-methyl-N-(phenyl)benzamide, I and 3-Acetoxy-2-methyl-N-(4-methylphenyl)benzamide, II. Compounds were characterized by FTIR, 1H NMR, 13C NMR and X-ray single crystal diffraction analysis techniques. Single crystal X-ray diffraction analyses show that while I crystallized in the orthorhombic system with space group Pbca, II crystallized in the triclinic system with space group P-1 and the asymmetric unit of II consists of two crystallographically independent molecules. Lattice constants are a = 7.9713 (3) Å, b = 9.5059 (3) Å, c = 37.1762 (2) Å, Z = 8 for I and a = 7.5579 (8) Å, b = 8.8601 (8) Å, c = 23.363 (3) Å, α = 97.011 (9) °, β = 96.932 (9)°, γ = 90.051 (8)°, Z = 4 for II. Crystallographic studies also show that the supramolecular structures were stabilized by intramolecular, intermolecular hydrogen bonds and Csbnd H … π interactions for both compounds. Characteristic amide bonds were observed in IR and NMR spectra.

The molecular structure and vibrational, 1H and 13C NMR spectra of lidocaine hydrochloride monohydrate

NASA Astrophysics Data System (ADS)

Badawi, Hassan M.; Förner, Wolfgang; Ali, Shaikh A.

2016-01-01

The structure, vibrational and NMR spectra of the local anesthetic drug lidocaine hydrochloride monohydrate salt were investigated by B3LYP/6-311G∗∗ calculations. The lidocaine·HCl·H2O salt is predicted to have the gauche structure as the predominant form at ambient temperature with NCCN and CNCC torsional angles of 110° and -123° as compared to 10° and -64°, respectively in the base lidocaine. The repulsive interaction between the two N-H bonds destabilized the gauche structure of lidocaine·HCl·H2O salt. The analysis of the observed vibrational spectra is consistent with the presence of the lidocaine salt in only one gauche conformation at room temperature. The 1H and 13C NMR spectra of lidocaine·HCl·H2O were interpreted by experimental and DFT calculated chemical shifts of the lidocaine salt. The RMSD between experimental and theoretical 1H and 13C chemical shifts for lidocaine·HCl·H2O is 2.32 and 8.21 ppm, respectively.

Defense Against Threat. Threat Recognition and Analysis Project

DTIC Science & Technology

1975-09-01

but clustering around it ( land affecting it) are other action structures of different character, now entering strongly on the world scene...seeks .o cap ur ^^’^^try to gestalts of cognition and affect , ^[Jj^ f c!anrPr or country, that put the signature of...TRAMSPORT 8, PETROL PRODUCTS 7.*, USR 27, JAP 18, IND Ik, - FRUITS +NUTS Ik, NATURAL GAS 17, LAMBSKINS 12, USR 30, PAK

Organogold oligomers: Exploiting iClick and aurophilic cluster formation to prepare solution stable Au 4 repeating units

DOE PAGES

Yang, Xi; Wang, Shanshan; Ghiviriga, Ion; ...

2015-05-19

A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt 3Au] 4(μ-N 3C 2C 6H 5) (1) and [PPhMe 2Au] 43C 2C 6H 5) (2) and {[PEt 3Au] 4[(μ-N 3C 2) 2-9,9-dihexyl-9H-fluorene]} n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysismore » reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. The degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

The hOGG1 Ser326Cys Gene Polymorphism and Breast Cancer Risk in Saudi Population.

PubMed

Alanazi, Mohammed; Pathan, Akbar Ali Khan; Shaik, Jilani P; Alhadheq, Abdullah; Khan, Zahid; Khan, Wajahatullah; Al Naeem, Abdulrahman; Parine, Narasimha Reddy

2017-07-01

The purpose of this study was to test the association between human 8-oxoguanine glycosylase 1 (hOGG1) gene polymorphisms and susceptibility to breast cancer in Saudi population. We have also aimed to screen the hOGG1 Ser326Cys polymorphism effect on structural and functional properties of the hOGG1 protein using in silico tools. We have analyzed four SNPs of hOGG1 gene among Saudi breast cancer patients along with healthy controls. Genotypes were screened using TaqMan SNP genotype analysis method. Experimental data was analyzed using Chi-square, t test and logistic regression analysis using SPSS software (v.16). In silco analysis was conducted using discovery studio and HOPE program. Genotypic analysis showed that hOGG1 rs1052133 (Ser326Cys) is significantly associated with breast cancer samples in Saudi population, however rs293795 (T >C), rs2072668 (C>G) and rs2075747 (G >A) did not show any association with breast cancer. The hOGG1 SNP rs1052133 (Ser326Cys) minor allele T showed a significant association with breast cancer samples (OR = 1.78, χ2 = 7.86, p = 0.02024). In silico structural analysis was carried out to compare the wild type (Ser326) and mutant (Cys326) protein structures. The structural prediction studies revealed that Ser326Cys variant may destabilize the protein structure and it may disturb the hOGG1 function. Taken together this is the first In silico study report to confirm Ser326Cys variant effect on structural and functional properties of hOGG1 gene and Ser326Cys role in breast cancer susceptibility in Saudi population.

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

Abdelbaky, Mohammed S.M.; Amghouz, Zakariae; Department of Materials Science and Metallurgical Engineering, University of Oviedo, Campus Universitario, 33203 Gijón

Novel metal phosphonate [CuLi(PPA)] [H{sub 3}PPA=3-phosphonopropionic acid] was synthesized hydrothermally and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. It crystallizes in the space group C2/c, with cell parameters a=21.617(2) Å, b=4.9269(2) Å, c=14.342(1) Å, β=132.3(2)°, and Z=8. Its framework is built up from a main trimer, acting as a secondary building unit (SBU), which is formed by vertex-shared between two (LiO{sub 4}) and one (Cu(1)O{sub 4}) polyhedra. These units repeat along b-axis forming infinite inorganic chains, these chains are in turn cross-linked by corner sharing with (Cu(2)O{sub 4}) polyhedra to producemore » inorganic layers lying in the bc-plane. The neighboring layers are connected through the PPA ligand, leading to a 3D pillared-layered structure. The topological analysis reveals that the compound exhibits 3,4,10-c net. Finally, magnetic susceptibility measurement of this compound over the temperature range of 2–300 K reveals the occurrence of weak antiferromagnetic intrachain interactions. - Graphical abstract: Hydrothermal synthesis and structural characterization of a novel lithium-copper phosphonate, formulated as [CuLi(PPA)] (H{sub 3}PPA=3-phosphonopropionic acid), have been reported. This compound has a 3D pillared-layered structure with 3,4,10-c net topology. The magnetic susceptibility data over the temperature range of 2–300 K reveals the occurrence of weak antiferromagnetic interactions. - Highlights: • Novel metal phosphonate, [CuLi(PPA)] (1), has been synthesized and characterized. • Compound 1 has a 3D pillared-layered structure with 3,4,10-c net topology. • Magnetic susceptibility data reveals the occurrence of weak antiferromagnetic interactions.« less

Microwave Spectrum and Structure of the Methane-Propane Complex

NASA Astrophysics Data System (ADS)

Peterson, Karen I.; Lin, Wei; Arsenault, Eric A.; Choi, Yoon Jeong; Novick, Stewart E.

2017-06-01

Methane is exceptional in its solid-phase orientational disorder that persists down to 24 K. Only below that temperature does the structure become partially ordered, and full crystallinity requires even lower temperatures and high pressures. Not surprisingly, methane appears to freely rotate in most van der Waals complexes, although two notable exceptions are CH_4-HF and CH_4-C_5H_5N. Of interest to us is how alkane interactions affect the methane rotation. Except for CH_4-CH_4, rotationally-resolved spectra of alkane-alkane complexes have not been studied. To fill this void, we present the microwave spectrum of CH_4-C_3H_8 which is the smallest alkane complex with a practical dipole moment. The microwave spectrum of CH_4-C_3H_8 was measured using the Fourier Transform microwave spectrometer at Wesleyan University. In the region between 7100 and 25300 MHz, we observed approximately 70 transitions that could plausibly be attributed to the CH_4-C_3H_8 complex (requiring high power and the proper mixture of gases). Of these, 16 were assigned to the A-state (lowest internal rotor state of methane) and four to the F-state. The A-state transitions were fitted with a Watson Hamiltonian using nine spectroscopic constants of which A = 7553.8144(97) MHz, B = 2483.9183(35) MHz, and C = 2041.8630(21) MHz. The A rotational constant is only 1.5 MHz higher than that of Ar-C_3H_8 and, since the a-axis of the complex passes approximately through the centers of mass of the subunits, this indicates a similar relative orientation. Thus, we find that the CH_4 is located above the plane of the propane. The center-of-mass separation of the subunits in CH_4-C_3H_8 is calculated to be 3.993 Å, 0.16 Å longer than the Ar-C_3H_8 distance of 3.825 Å, a reasonable difference considering the larger van der Waals radius of CH_4. The four F-state lines, which were about twice as strong as the A-state lines, could be fitted to A, B, and C rotational constants, and further analysis is in progress.

The synthesis and structure of a chiral 1D aluminophosphate chain compound: d-Co(en) 3[AlP 2O 8]·6.5H 2O

NASA Astrophysics Data System (ADS)

Chen, Peng; Li, Jiyang; Yu, Jihong; Wang, Yu; Pan, Qinhe; Xu, Ruren

2005-06-01

A new chiral one-dimensional (1D) aluminophosphate chain compound [ d-Co(en) 3][AlP 2O 8]·6.5H 2O (designated AlPO-CJ22) has been hydrothermally synthesized by using the optically pure d-Co(en) 3I 3 complex as the template. Single-crystal structural analysis reveals that its structure is built up from alternating connection of AlO 4 and PO 2(=O 2) tetrahedra to form corner-shared Al 2P 2 four-membered ring (4-MR) chains. The d-Co(en) 33+ complex cations extended along the 2 1 screw axis interact with the inorganic chains through hydrogen-bonds of N⋯O atoms in a helical fashion. Optical rotation measurement shows that AlPO-CJ22 is chiral as with d-Co(en) 33+ complex cations. Crystal data: orthorhombic, I2 12 12 1, a=8.5573(8) Å, b=22.613(2) Å, c=22.605(2) Å, Z=8, R1=0.067, wR2=0.1291, and Flack parameter: -0.02(3). CCDC number: 254179.

[Cloning and bioinformatics analysis of abscisic acid 8'-hydroxylase from Pseudostellariae Radix].

PubMed

Li, Jun; Long, Deng-Kai; Zhou, Tao; Ding, Ling; Zheng, Wei; Jiang, Wei-Ke

2016-07-01

Abscisic acid 8'-hydroxylase was one of key enzymes genes in the metabolism of abscisic acid (ABA). Seven menbers of abscisic acid 8'-hydroxylase were identified from Pseudostellaria heterophylla transcriptome sequencing results by using sequence homology. The expression profiles of these genes were analyzed by transcriptome data. The coding sequence of ABA8ox1 was cloned and analyzed by informational technology. The full-length cDNA of ABA8ox1 was 1 401 bp,with 480 encoded amino acids. The predicated isoelectric point (pI) and relative molecular mass (MW) were 8.55 and 53 kDa,respectively. Transmembrane structure analysis showed that there were 21 amino acids in-side and 445 amino acids out-side. High level of transcripts can detect in bark of root and fibrous root. Multi-alignment and phylogenetic analysis both show that ABA8ox1 had a high similarity with the CYP707As from other plants,especially with AtCYP707A1 and AtCYP707A3 in Arabidopsis thaliana. These results lay a foundation for molecular mechanism of tuberous root expanding and response to adversity stress. Copyright© by the Chinese Pharmaceutical Association.

Synthesis, structure, antitumor activity of novel pharmaceutical co-crystals based on bispyridyl-substituted α, β-unsaturated ketones with gallic acid

NASA Astrophysics Data System (ADS)

Liu, Lian-Dong; Liu, Shu-Lian; Liu, Zhi-Xian; Hou, Gui-Ge

2016-05-01

Three novel pharmaceutical co-crystals, (A)·(gallic acid) (1), (B)·(gallic acid) (2), and (C)·(gallic acid) (3) were generated based on 2,6-bis((pyridin-4-yl)methylene)cyclohexanone (A), N-methyl-3,5-bis((pyridin-3-yl)methylene)-4-piperidone (B), N-methyl-3,5-bis((pyridin-4-yl)methylene)-4-piperidone (C) with gallic acid, respectively. They are characterized by elemental analysis, FTIR spectroscopy, 1H NMR and single-crystal X-ray diffraction. Structural analysis reveals that two pharmaceutical ingredients link each other into H-bonding-driven 3D network in 1, 2, or 2D plane in 3. In addition, their antitumor activities against human neoplastic cell lines A549, SGC-7901, MCF-7, OVCA-433, HePG2 and cytotoxicity for HUVEC cell lines by CCK-8 method were evaluated primarily. Compared with gallic acid and free A, B and C, their antitumor activities have improved distinctly, while cytotoxicities have reduced markedly, especially for co-crystal 1. This is mainly because of the synergistic effect between pharmaceutical ingredients A, B, and C and gallic acid.

Coordination geometry of lead carboxylates - spectroscopic and crystallographic evidence.

PubMed

Catalano, Jaclyn; Murphy, Anna; Yao, Yao; Yap, Glenn P A; Zumbulyadis, Nicholas; Centeno, Silvia A; Dybowski, Cecil

2015-02-07

Despite their versatility, only a few single-crystal X-ray structures of lead carboxylates exist, due to difficulties with solubility. In particular, the structures of long-chain metal carboxylates have not been reported. The lone electron pair in Pb(ii) can be stereochemically active or inactive, leading to two types of coordination geometries commonly referred to as hemidirected and holodirected structures, respectively. We report (13)C and (207)Pb solid-state NMR and infrared spectra for a series of lead carboxylates, ranging from lead hexanoate (C6) to lead hexadecanoate (C18). The lead carboxylates based on consistent NMR parameters can be divided in two groups, shorter-chain (C6, C7, and C8) and longer-chain (C9, C10, C11, C12, C14, C16, and C18) carboxylates. This dichotomy suggests two modes of packing in these solids, one for the short-chain lead carboxylates and one for long-chain lead carboxylates. The consistency of the (13)C and (207)Pb NMR parameters, as well as the IR data, in each group suggests that each motif represents a structure characteristic of each subgroup. We also report the single-crystal X-ray diffraction structure of lead nonanoate (C9), the first single-crystal structure to have been reported for the longer-chain subgroup. Taken together the evidence suggests that the coordination geometry of C6-C8 lead carboxylates is hemidirected, and that of C9-C14, C16 and C18 lead carboxylates is holodirected.

Hydrothermal synthesis, structural elucidation, spectroscopic studies, thermal behavior and luminescence properties of a new 3-d compound: FeAlF2(C10H8N2)(HPO4)2(H2O)

NASA Astrophysics Data System (ADS)

Bouzidia, Nabaa; Salah, Najet; Hamdi, Besma; Ben Salah, Abdelhamid

2017-04-01

The study of metal phosphate has been a proactive field of research thanks to its applied and scientific importance, especially in terms of the development of optical devices such as solid state lasers as well as optical fibers. The present paper seeks to investigate the synthesis, crystal structure, elemental analysis and properties of FeAlF2(C10H8N2)(HPO4)2(H2O) compound investigated by spectroscopic studies (FT-IR and FT-Raman), thermal behavior and luminescence. The Hirshfeld surface analysis and 2-D fingerprint plot have been performed to explore the behavior of these weak interactions and crystal cohesion. This investigation shows that the molecules are connected by hydrogen bonds of the type Osbnd H⋯O and Osbnd H⋯F. In addition, the 2,2'‒bipyridine ligand plays a significant role in the construction of 3-D supramolecular framework via π‒π stacking. FT‒IR and FT‒Raman spectra were used so as to ease the responsibilities of the vibration modes of the title compound. The thermal analysis (TGA) study shows a mass loss evolution as a temperature function. Finally, the optical properties were evaluated by photoluminescence spectroscopy.

Isolation and characterization of cDNA clones for human erythrocyte beta-spectrin.

PubMed Central

Prchal, J T; Morley, B J; Yoon, S H; Coetzer, T L; Palek, J; Conboy, J G; Kan, Y W

1987-01-01

Spectrin is an important structural component of the membrane skeleton that underlies and supports the erythrocyte plasma membrane. It is composed of nonidentical alpha (Mr 240,000) and beta (Mr 220,000) subunits, each of which contains multiple homologous 106-amino acid segments. We report here the isolation and characterization of a human erythroid-specific beta-spectrin cDNA clone that encodes parts of the beta-9 through beta-12 repeat segments. This cDNA was used as a hybridization probe to assign the beta-spectrin gene to human chromosome 14 and to begin molecular analysis of the gene and its mRNA transcripts. RNA transfer blot analysis showed that the reticulocyte beta-spectrin mRNA is 7.8 kilobases in length. Southern blot analysis of genomic DNA revealed the presence of restriction fragment length polymorphisms (RFLPs) within the beta-spectrin gene locus. The isolation of human spectrin cDNA probes and the identification of closely linked RFLPs will facilitate analysis of mutant spectrin genes causing congenital hemolytic anemias associated with quantitative and qualitative spectrin abnormalities. Images PMID:3478706

Synthetic endeavors on cadmium species bearing glycolate and aromatic chelators with structure-specific biotoxic correlations in vitro.

PubMed

Iordanidou, C; Tsave, O; Gabriel, C; Hatzidimitriou, A; Yavropoulou, M P; Mateescu, C; Salifoglou, A

2017-11-01

Cadmium is a well-known metallotoxin widespread in the environment and easily reaching cellular targets in lower and higher organisms, including humans. The form(s) of that metal ion through which it interacts with biomolecular targets in a cellular milieu are critical in cell survival. Poised to investigate the structure-specific activity of Cd(II) in a cellular environment and delve into the associated biotoxic processes, binary and ternary systems of that metal ion in the presence of the physiological α-hydroxycarboxylic acid glycolic acid and aromatic (N,N')-binders 2,2'-bipyridine (2,2'-bipy) and 4,4'-bipyridine (4,4'-bipy) were examined synthetically in aqueous media and a pH-specific fashion. The arising new materials [Cd(C 2 H 3 O 3 ) 2 ] n (1), [Cd(C 2 H 3 O 3 )(C 10 H 8 N 2 )(NO 3 )] n ·nH 2 O (2), and {[Cd(C 2 H 3 O 3 )(C 10 H 8 N 2 )(H 2 O)](NO 3 )} n ·2nH 2 O (3) project coordination polymers, which were physicochemically characterized through elemental analysis, FT-IR, NMR, luminescence and X-ray crystallography. The distinct spectroscopic features of 1-3, with luminescence exemplifying distinct behavior (2,3), further corroborated by crystallographic analysis, lend credence to a structure-specific selection of species employed in ensuing in vitro biological studies. The emerging results in two different cell lines (3T3-L1, Saos-2) reveal a concentration-dependent, structure-specific and cell line-specific toxicity profile of Cd(II), reflecting its coordination composition and formulation, rendering it soluble and bioavailable (1,2). Mechanistic information riding on caspase-dependent investigation unravels that metal ion's specific behavior compromising cell survival and integrity. Employment of ethylenediamine tetraacetic acid (EDTA) a) shows efficient sequestration of Cd(II) away from its toxic reactivity denoting the strength of interactions involved, and b) lends credence to further development of appropriately configured organic binders, selectively providing molecular protection from Cd(II) toxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Zn-doping on structural and magnetic properties of copper ferrite nanoparticles

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

Gautam, Nisha; Thirupathi, Gadipelly; Singh, Rajender

2016-05-23

The nanoparticles of CuFe{sub 2}O{sub 4} (CF) and Cu{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} (CZF) were synthesized using co-precipitation method to study the effect of Zn doping in Cu-ferrite. The X-ray diffraction (XRD) patterns were well fitted with two-phase structure using Rietveld analysis as Fd-3 m space group (spinel system) and C12/c1 space group (monoclinic system CuO-phase). The average crystallite size of the CF and CZF nanoparticles for spinel structure are 6 and 7 nm respectively. The spinel phase fraction is increased from 56% to 71% with Zn-doping of 20% in CF. The transmission electron micrograph analysis showed the narrow size distribution formore » CZF nanoparticles. The magnetization plots as a function of magnetic field (M (H)) of CF and CZF nanoparticles indicate superparamagnetic behavior. The magnetization is increased with Zn-doping in CF. The stable spinel Cu-ferrite can be obtained with Zn-doping in CF.« less

Structural characterization of new Schiff bases of sulfamethoxazole and sulfathiazole, their antibacterial activity and docking computation with DHPS protein structure.

PubMed

Mondal, Sudipa; Mandal, Santi M; Mondal, Tapan Kumar; Sinha, Chittaranjan

2015-01-01

New Schiff bases (1, 2) of substituted salicylaldehydes and sulfamethoxazole (SMX)/sulfathiazole (STZ) are synthesized and characterized by elemental analysis and spectroscopic data. Single crystal X-ray structure of one of the compounds (E)-4-((3,5-dichloro-2-hydroxybenzylidene)amino)-N-(5-methylisoxazol-3-yl)benzenesulfonamide (1c) has been determined. Antimicrobial activities of the Schiff bases and parent sulfonamides (SMX, STZ) have been examined against several Gram-positive and Gram-negative bacteria and sulfonamide resistant pathogens; the lowest MIC is observed for (E)-4-((3,5-dichloro-2-hydroxybenzylidene)amino)-N-(thiazol-2-yl)benzene sulfonamide (2c) (8.0 μg mL(-1)) and (E)-4-((3,5-dichloro-2-hydroxybenzylidene)amino)-N-(5-methylisoxazol-3-yl)benzene sulfonamide (1c) (16.0 μg mL(-1)) against sulfonamide resistant pathogens. DFT optimized structures of the Schiff bases have been used to carry out molecular docking studies with DHPS (dihydropteroate synthase) protein structure (downloaded from Protein Data Bank) using Discovery Studio 3.5 to find the most preferred binding mode of the ligand inside the protein cavity. The theoretical data have been well correlated with the experimental results. Cell viability assay and ADMET studies predict that 1c and 2c have good drug like characters. Copyright © 2015 Elsevier B.V. All rights reserved.

Fine Structure in Multi-Phase Zr8Ni21-Zr7Ni10-Zr2Ni7 Alloy Revealed by Transmission Electron Microscope

PubMed Central

Shen, Haoting; Bendersky, Leonid A.; Young, Kwo; Nei, Jean

2015-01-01

The microstructure of an annealed alloy with a Zr8Ni21 composition was studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of three phases, Zr8Ni21, Zr2Ni7, and Zr7Ni10, was confirmed by SEM/X-ray energy dispersive spectroscopy compositional mapping and TEM electron diffraction. Distribution of the phases and their morphology can be linked to a multi-phase structure formed by a sequence of reactions: (1) L → Zr2Ni7 + L’; (2) peritectic Zr2Ni7 + L’ → Zr2Ni7 + Zr8Ni21 + L”; (3) eutectic L” → Zr8Ni21 + Zr7Ni10. The effect of annealing at 960 °C, which was intended to convert a cast structure into a single-phase Zr8Ni21 structure, was only moderate and the resulting alloy was still multi-phased. TEM and crystallographic analysis of the Zr2Ni7 phase show a high density of planar (001) defects that were explained as low-energy boundaries between rotational variants and stacking faults. The crystallographic features arise from the pseudo-hexagonal structure of Zr2Ni7. This highly defective Zr2Ni7 phase was identified as the source of the broad X-ray diffraction peaks at around 38.4° and 44.6° when a Cu-K was used as the radiation source. PMID:28793460

Structural characterization of polysaccharides from bamboo

NASA Astrophysics Data System (ADS)

Kamil, Ruzaimah Nik Mohamad; Yusuf, Nur'aini Raman; Yunus, Normawati M.; Yusup, Suzana

2014-10-01

The alkaline and water soluble polysaccharides were isolate by sequential extractions with distilled water, 60% ethanol containing 1%, 5% and 8% NaOH. The samples were prepared at 60 °C for 3 h from local bamboo. The functional group of the sample were examined using FTIR analysis. The most precipitate obtained is from using 60% ethanol containing 8% NaOH with yield of 2.6%. The former 3 residues isolated by sequential extractions with distilled water, 60% ethanol containing 1% and 5% NaOH are barely visible after filtering with cellulose filter paper. The FTIR result showed that the water-soluble polysaccharides consisted mainly of OH group, CH group, CO indicates the carbohydrate and sugar chain. The sample weight loss was slightly decreased with increasing of temperature.

Synthesis, structure and topological analysis of glycine templated highly stable cadmium sulfate framework: A New Lewis Acid catalyst

NASA Astrophysics Data System (ADS)

Paul, Avijit Kumar

2018-04-01

One new open-framework two-dimensional layer, [Cd(NH3CH2COO)(SO4)], I, has been synthesized using amino acid as templating agent. Single crystal structural analysis shows that the compound crystallizes in monoclinic cell with non-centrosymmetric space group P21, a = 4.9513(1) Å, b = 7.9763(2) Å, c = 8.0967(2) Å, β = 105.917(1)° and V = 307.504(12) Å3. The compound has connectivity between the Cd-centers and the sulfate units forming a two-dimensional layer structure. Sulfate unit is coordinated to metal center with η3, μ4 mode possessing a coordination free oxygen atom. The zwitterionic form of glycine molecule is present in the structure bridging with two metal centers through μ2-mode by carboxylate oxygens. The topological analysis reveals that the two-dimensional network is formed with a novel 4- and 6-connected binodal net of (32,42,52)(34,44,54,63) topology. Although one end of the glycine molecule is free from coordination, the structure is highly stable up to 350 °C. Strong N-H⋯ O hydrogen bonding interactions play an important role in the stabilization and formation of three-dimensional supramolecular structure. The cyanosilylation of imines using the present compounds as heterogeneous catalyst indicates good catalytic behavior. The present study illustrates the usefulness of the amino acid for the structure building in less studied sulfate based framework materials as well as designing of new heterogeneous catalysts for the broad application. The compound has also been characterized through elemental analysis, PXRD, IR, SEM and TG-DT studies.

Stereometric parameters change vs. Topographic Change Analysis (TCA) agreement in Heidelberg Retina Tomography III (HRT-3) early detection of clinical significant glaucoma progression.

PubMed

Dascalu, A M; Cherecheanu, A P; Stana, D; Voinea, L; Ciuluvica, R; Savlovschi, C; Serban, D

2014-01-01

to investigate the sensitivity and specificity of the stereometric parameters change analysis vs. Topographic Change Analysis in early detection of glaucoma progression. 81 patients with POAG were monitored for 4 years (GAT monthly, SAP at every 6 months, optic disc photographs and HRT3 yearly). The exclusion criteria were other optic disc or retinal pathology; topographic standard deviation (TSD>30; inter-test variation of reference height>25 μm. The criterion for structural progression was the following: at least 20 adjacent super-pixels with a clinically significant decrease in height (>5%). 16 patients of the total 81 presented structural progression on TCA. The most useful stereometric parameters for the early detection of glaucoma progression were the following: Rim Area change (sensitivity 100%, specificity 74.2% for a "cut-off " value of -0.05), C/D Area change (sensitivity 85.7%, specificity 71.5% for a "cut off " value of 0.02), C/D linear change (sensitivity 85.7%, specificity 71.5% for a "cut-off " value of 0.02), Rim Volume change (sensitivity 71.4%, specificity 88.8% for a "cut-off " value of -0.04). RNFL Thickness change (<0) was highly sensitive (82%), but less specific for glaucoma progression (45,2%). Changes of the other stereometric parameters have a limited diagnostic value for the early detection of glaucoma progression. TCA is a valuable tool for the assessment of the structural progression in glaucoma patients and its inter-test variability is low. On long-term, the quantitative analysis according to stereometric parameters change is also very important. The most relevant parameters to detect progression are RA, C/D Area, Linear C/D and RV.

Carotid intima-media thickness as a cardiovascular risk marker in pediatric end-stage renal disease patients on dialysis and in renal transplantation.

PubMed

Delucchi, A; Dinamarca, H; Gainza, H; Whitttle, C; Torrealba, I; Iñiguez, G

2008-11-01

Cardiovascular diseases are the principal cause of morbidity and mortality among young adults with chronic renal disease. Atherosclerotic structural changes as detected by high-resolution B-mode ultrasonography preceed clinical findings by several decades. The carotid intima-media thickness (cIMT) is being used as a marker of early atherosclerosis. We determined the cIMT of common carotid artery (CCA) in 8 asymptomatic children on dialysis or 12 after renal transplantation for comparison with 30 healthy controls. This prospective study of 40 children showed a mean age of 13.5 years (range, 8 to 18). We evaluated cIMT, hemoglobin, serum creatinine levels, lipid profile, and homeostasis model assessment (HOMA). The statistical analysis for variables with normal distribution was Student's t test. Parameters with a non-normal distribution were evaluated by the Mann-Whitney or Spearman correlation analysis with P < .05 considered statistically significant. The mean measurements of cIMT (mm) of both CCA were dialysis 0.450 +/- 0.042; transplant 0.467 +/- 0.033, and controls 0.380 +/- 0.009 (P < .03). The homa levels of 2.45 +/- 0.98 for dialysis and 1.8 +/- 0.62 for transplant, were both significantly higher than the control group (0.8 +/- 0.09; P < .01). The Ca x P product was higher in dialysis vs transplant group: 63.0 +/- 10.0 versus 46.2 +/- 2.2 (P < .03). The intact parathyroid hormone levels were 666.7 +/- 276.7 versus 44.2 +/- 2.8, respectively (P < .008). The low-density lipoprotein cholesterol was 129.0 +/- 23.1 versus 80.8 +/- 10.6, respectively (P < .04). The cIMT correlated with the duration of dialysis before transplantation. Changes in IMT can be detected by ultrasonography in early childhood in uremic patients. The etiology of atherosclerosis is multifactorial in children with end-stage renal disease. It seems possible to prevent or improve the factors related to cardiovascular risk in these patients.

Crystal structure, quantum mechanical investigation, IR and NMR spectroscopy of two new organic salts: (C8H12NO)·[NO3] (I) and (C8H14N4)·[ClO4]2 (II)

NASA Astrophysics Data System (ADS)

Bayar, I.; Khedhiri, L.; Soudani, S.; Lefebvre, F.; Pereira da Silva, P. S.; Ben Nasr, C.

2018-06-01

Two new organic-inorganic hybrid materials, 4-methoxybenzylammonium nitrate, (C8H12NO)·[NO3] (I), and 2-(1-piperazinyl)pyrimidinium bis(perchlorate), (C8H14N4)·[ClO4]2(II), have been synthesized by an acid/base reaction at room temperature, their structures were determined by single crystal X-ray diffraction. Compound (I) crystallizes in the orthorhombic system and Pnma space group with a = 15.7908 (7), b = 6.8032 (3), c = 8.7091 (4) Å, V = 935.60 (7) Å3 with Z = 4. Full-matrix least-squares refinement converged at R = 0.038 and wR(F2) = 0.115. Compound (II) belongs to the monoclinic system, space group P21/c with the following parameters: a = 10.798(2), b = 7.330(1), c = 21.186(2) Å, β = 120.641 (4)°, V = 1442.7 (3) Å3and Z = 4. The structure was refined to R = 0.044, wR(F2) = 0.132. In the structures of (I) and (II), the anionic and cationic entities are interconnected by hydrogen bonding contacts forming three-dimensional networks. Intermolecular interactions were investigated by Hirshfeld surfaces and the contacts of the four different chloride atoms in (II) were compared. The Molecular Electrostatic Potential (MEP) maps and the HOMO and LUMO energy gaps of both compounds were computed. The vibrational absorption bands were identified by infrared spectroscopy. These compounds were also investigated by solid-state 13C, 35Cl and 15N NMR spectroscopy. DFT calculations allowed the attribution of the IR and NMR bands.

Crystal structure and theoretical studies of derivative of imidazo-1,2,4-triazine

NASA Astrophysics Data System (ADS)

Dybała, Izabela; Sztanke, Krzysztof

2016-09-01

In this study, we present the result of X-ray structure analysis of methyl [8-(3-chlorophenyl)-4-oxo-2,3,4,6,7,8-heksahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate (1). The molecule conformation is flat, with a chlorophenyl substituent and the ester moiety lying in the plain of the heterobicyclic scaffold. Its conformation is stabilized by an intramolecular Nsbnd H…O hydrogen bond. Within the crystalline structure of 1, molecules associate with one another by weak Csbnd H…O, Csbnd H…Cl and Csbnd H…π bonds. The molecular and crystal structure of 1 was compared with the previously described structurally similar compound possessing the same bicyclic rigid core and similar chemical nature of the functional ester moiety. Very interesting differences in molecules geometry and association were observed. Non-covalent bonds within the crystals are additionally visualized by determination of Hirshfeld surfaces. Moreover, the quantum chemical calculation for 1 in the gas phase were carried out. The DFT calculation methods was used to optimize of molecule geometry and obtain molecular energy profiles with respect to selected torsion angles. The quantum chemical conformational analysis that was carried out for compound 1 in the gas phase suggests that in the solid state the molecules adopt the minimum energy conformation.

Experimental and theoretical investigation of three-dimensional nitrogen-doped aluminum clusters AI 8N - and AI 8N

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

Wang, Leiming; Huang, Wei; Wang, Lai S.

The structure and electronic properties of the Al 8N - and Al 8N clusters were investigated by combined photoelectron spectroscopy and ab initio studies. Congested photoelectron spectra were observed and experimental evidence was obtained for the presence of multiple isomers for Al 8N - Global minimum searches revealed several structures for Al 8N - with close energies. The calculated vertical detachment energies of the two lowest-lying isomers, which are of C 2v and C s symmetry, respectively, were shown to agree well with the experimental data. Unlike the three-dimensional structures of Al 6N - and Al 7N -, in whichmore » the dopant N atom has a high coordination number of 6,the dopant N atom in the two low-lying isomers of Al 8N - has a lower coordination number of 4 and 5, respectively. The competition between the Al–Al and Al–N interactions are shown to determine the global minimum structures of the doped aluminum clusters and results in the structural diversity for both Al 8N - and Al8N. © 2009 American Institute of Physics« less

Pressure-induced ferroelectric to paraelectric transition in LiTaO 3 and (Li,Mg)TaO 3

DOE PAGES

Yamanaka, Takamitsu; Nakamoto, Yuki; Takei, Fumihiko; ...

2016-02-16

X-ray powder diffraction and Raman scattering of LiTaO 3 (LT) and (Li,Mg)TaO 3 (LMT) have been measured under pressure up to 46 GPa. Above 30 GPa, the ferroelectric rhombohedral phase (R3c, Z – 6) of LiTaO 3 transforms to a paraelectric orthorhombic phase (Pnma with Z – 4) with a large hysteresis. Rietveld profile fitting analysis shows that the Li-O bond is compressed and approaches that of Ta-O with pressure. The cation distribution analysis of the orthorhombic perovskite structure shows that Li and Ta are located in the octahedral 8-fold coordination sites. Difference Fourier |F obs(hkl)| - |F cal(hkl)| mapsmore » of LiTaO 3 and (Li,Mg)TaO 3 indicate polarization in the c axis direction and a more distinct electron density distribution around the Ta position for (Li,Mg)TaO 3 compared to LiTaO 3. The observed effective charges indicate that for (Li,Mg)TaO 3 without vacancies Ta 5+ becomes less ionized as a function of Mg substitution. Considering both site occupancy and effective charge analysis, Ta 5+ is reduced to Ta 4.13+. Mg 2+ and O 2- change to Mg 1.643+ and O 1.732 -, respectively. The space- and time-averaged structures of the dynamical vibration of atoms can be elucidated from the electron density analysis by difference Fourier and temperature factors T(hkl) in the structure refinement. The refinement of the temperature factor is consistent with the cation distribution assuming full stoichiometry. The residual electron density induced from the excess electron in (Li,Mg)TaO 3 indicates more electrons around the Ta site, as confirmed by the effective charge analysis. Raman spectra of LiTaO 3 and (Li,Mg)TaO 3 show notable changes over the measured pressure range. Raman peaks centered at 250 cm –1 and 350 cm –1 at ambient pressure merge above 8 GPa, which we associate with the diminishing of difference in distances between Li-O and Ta-O bonds with pressure in both materials. Finally, Raman spectra show significant changes at 28 GPa and 33 GPa for LT and LMT, respectively, due to the structural transition from R3c to Pnma consistent with the x-ray diffraction results.« less

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

Rettie, Alexander J. E.; Sturza, Mihai; Malliakas, Christos D.

The two-dimensional material KCu 3–xSe 2 was synthesized using both a K 2Se 3 flux and directly from the elements. It crystallizes in the CsAg 3S 2 structure (monoclinic space group C2/m with a = 15.417(3) Å, b = 4.0742(8) Å, c = 8.3190(17) Å, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu 3–xSe 2]– layers separated by K + ions. Thermal analysis indicated that KCu 3–xSe 2 melts congruently at ~755 °C. UV–vis spectroscopy showed an optical band gap of ~1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurementsmore » on single crystals yielded an in-plane resistivity of ~6 × 10 –1 Ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K –1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm 2 V –1 s –1) holes caused by relatively flat valence bands with substantial Cu 3d character and a significant concentration of Cu ion vacancy defects (p ~ 10 19 cm –3) in this material. In conclusion, electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.« less

A new series of mixed oxalates MM'(C 2O 4) 3(H 2O) 3· nH 2O (M = Cd, Hg, Pb; M' = Zr, Hf) based on eight-fold coordinated metals: Synthesis, crystal structure from single-crystal and powder diffraction data and thermal behaviour

NASA Astrophysics Data System (ADS)

Gavilan, Elisabeth; Audebrand, Nathalie; Jeanneau, Erwann

2007-11-01

A new series of mixed oxalates MM'(C 2O 4) 3(H 2O) 3· nH 2O (M = Cd, Hg, Pb; M' = Zr, Hf) has been prepared. The crystal structures have been solved from single-crystal and powder diffraction data. The isotypical compounds crystallise with space group P2 1/ c (No. 14). The structures consist of honeycomb layers formed by eight-fold coordinated metals, in a distorted square-based antiprismatic conformation, connected together via oxalates which act as bidentate ligands and also as monodentate in a less-common μ3-bridging mode. Sheets are built from two shifted honeycomb layers and linked to each other through a hydrogen network. The resulting frameworks of the series display a compact two-dimensional arrangement of polyhedra MO 8 and M'O 8. Weakly-bonded water molecules are located between and within the sheets. Comparisons with the 3D open-framework structures of related metal oxalates are made. The dehydration processes occur in three or four steps. The final products are MO, M'O 2 and PbZrO 3 resulting from the sublimation of PbO in air. The size of PbZrO 3 crystallites, which are on average isotropic, has been evaluated to be 1055 Å from line-broadening analysis.

Synthesis, structural analysis, Hirshfeld surface, spectroscopic characterization and, in vitro, antioxidant activity of a novel organic cyclohexaphosphate

NASA Astrophysics Data System (ADS)

Fezai, Ramzi; Mezni, Ali; Rzaigui, Mohamed

2018-02-01

The new hybrid [4-Cl-2-(CH3)C6H3NH3]6P6O18·2H2O was synthesized under normal conditions of temperature and pressure. Single crystal X-ray diffraction study was used to identify its structure. It revealed that this organic cyclohexaphosphate crystallized in the P 1 bar triclinic space group with a = 10.41 (10) Å b = 10.94 (7) Å, c = 15.45 (10) Å, α = 77.37 (8), β = 89.75 (8)°, γ = 61.69 (7)°, V = 1501 (2) Å3 and Z = 1. In the crystal framework, the assembling of the three dimensional (3D) structure is formed by intermolecular hydrogen bonds and Van Der Waals interactions. A spectroscopic characterization was carried out to elucidate the structure (UV-Vis, FTIR, 31P MAS-NMR and fluorescent properties). The thermal stability was studied by TG-DTA diagrams under argon atmosphere. Furthermore, 3-D Hirshfeld surfaces in combination with 2-D fingerprint plots were carried out. This compound was also evaluated for its antioxidant activity; four tests were done, in vitro, 1,1-diphenyl-2-picrylhydrazyl (DPPH•), hydroxyl scavenging ability (OH•), ferric reducing power (FRP) and ferrous ion chelating (FIC) ability, using ascorbic acid as a control.

Structure of β-AgGaO{sub 2}; ternary I–III–VI{sub 2} oxide semiconductor with a wurtzite-derived structure

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

Nagatani, Hiraku; Suzuki, Issei; Kita, Masao

2015-02-15

The structure of the wurtzite-derived β-AgGaO{sub 2} was refined by Rietveld analysis of high-resolution powder diffraction data obtained using synchrotron X-ray radiation. The space group of the crystal is Pna2{sub 1} with lattice parameters of a{sub 0}=5.56175 Å, b{sub 0}=7.14749 Å, and c{sub 0}=5.46875 Å. The deviation of O–Ag–O and M–O–M bond angles from the regular tetrahedral angle of 109.5° was very large at ∼8° and ∼11°, respectively. The electronic structure of β-AgGaO{sub 2} is discussed based on its structure, and the indirect band gap of β-AgGaO{sub 2} was related to significant tetrahedral distortion. Although β-AgGaO{sub 2} decomposes into metallicmore » silver and Ga{sub 2}O{sub 3} at a high temperature in any atmosphere, β-AgGaO{sub 2} is stable up to 690 °C under an O{sub 2} atmosphere. No direct transformation from the wurtzite-derived phase to a delafossite phase occurs in β-AgGaO{sub 2}. - Graphical abstract: Crystal structure of β-AgGaO{sub 2} was refined by Rietveld analysis. AgO{sub 4} and O(Ag,Ga){sub 4} tetrahedra are significantly distorted from ideal tetrahedron. - Highlights: • Orthorhombic β-AgGaO{sub 2} with a wurtzite-derived β-NaFeO{sub 2} structure was synthesized. • Its structure was refined by Rietveld analysis of high-resolution XRD data. • Silver and oxygen tetrahedra are significantly distorted from an ideal tetrahedron. • The extent of this tetrahedral distortion is related to the band gap nature. • β-AgGaO{sub 2} is a metastable phase but is stable up to 690 °C in an O{sub 2} atmosphere.« less

Molecular basis of thermostability enhancement of Renilla luciferase at higher temperatures by insertion of a disulfide bridge into the structure.

PubMed

Fanaei Kahrani, Zahra; Emamzadeh, Rahman; Nazari, Mahboobeh; Rasa, Seyed Mohammad Mahdi

2017-02-01

Renilla luciferase (RLuc), also known as Renilla-luciferin 2-monooxygenase, is a light producing enzyme used in many biotechnological applications such as bioreporters. However, its kinetics stability -especially at higher temperatures- is a limiting factor for developing thermostable bioreporters. The aim of this study was to improve the stability of super Renilla luciferase 8 (SRLuc 8) which is a red-emitter variety of RLuc at higher temperatures, by introduction of a disulfide bridge into its structure. In this study, the choice of the proper disulfide bond formation was based on computational methods and enzyme functionality (active site position) which is called geometric-functional method. N45 and A71 at the N-terminal of the enzyme were selected for directed evolution. The engineered luciferase was called C-SRLuc 8 and its activity and stability were assayed. The results indicated that the kinetic stability of C-SRLuc 8 increased significantly at 60°C to 70°C as compared to SRLuc 8; the residual activity of C-SRLuc 8 was approximately 20% after incubation at 65°C for 5min. Moreover, the enzyme activity decreased compared with SRLuc 8. The molecular basis of the structural changes was considered using molecular dynamics simulations and the results indicated that the N45C/A71C crosslink was involved in a hotspot foldon which seemed to be the rate-limiting step of conformational collapse at higher temperatures. The present study may provide an opportunity for the development of the next-generation of thermostable RLuc-based biosensors. Copyright © 2016. Published by Elsevier B.V.

The galactolipase activity of Fusarium solani (phospho)lipase.

PubMed

Jallouli, Raida; Othman, Houcemeddine; Amara, Sawsan; Parsiegla, Goetz; Carriere, Frédéric; Srairi-Abid, Najet; Gargouri, Youssef; Bezzine, Sofiane

2015-03-01

The purified (phospho)lipase of Fusarium solani (FSL), was known to be active on both triglycerides and phospholipids. This study aimed at assessing the potential of this enzyme in hydrolyzing galactolipids. FSL was found to hydrolyze at high rates of synthetic medium chains monogalactosyldiacylglycerol (4658±146U/mg on DiC8-MGDG) and digalactosyldiacylglycerol (3785±83U/mg on DiC8-DGDG) and natural long chain monogalactosyldiacylglycerol extracted from leek leaves (991±85U/mg). It is the microbial enzyme with the highest activity on galactolipids identified so far with a level of activity comparable to that of pancreatic lipase-related protein 2. FSL maximum activity on galactolipids was measured at pH8. The analysis of the hydrolysis product of natural MGDG from leek showed that FSL hydrolyzes preferentially the ester bond at the sn-1 position of galactolipids. To investigate the structure-activity relationships of FSL, a 3D model of this enzyme was built. In silico docking of medium chains MGDG and DGDG and phospholipid in the active site of FSL reveals structural solutions which are in concordance with in vitro tests. Copyright © 2015 Elsevier B.V. All rights reserved.

Fine mapping analysis confirms and strengthens linkage of four chromosomal regions in familial hypospadias

PubMed Central

Söderhäll, Cilla; Körberg, Izabella Baranowska; Thai, Hanh T T; Cao, Jia; Chen, Yougen; Zhang, Xufeng; Shulu, Zu; van der Zanden, Loes F M; van Rooij, Iris A L M; Frisén, Louise; Roeleveld, Nel; Markljung, Ellen; Kockum, Ingrid; Nordenskjöld, Agneta

2015-01-01

Hypospadias is a common male genital malformation and is regarded as a complex disease affected by multiple genetic as well as environmental factors. In a previous genome-wide scan for familial hypospadias, we reported suggestive linkage in nine chromosomal regions. We have extended this analysis by including new families and additional markers using non-parametric linkage. The fine mapping analysis displayed an increased LOD score on chromosome 8q24.1 and 10p15 in altogether 82 families. On chromosome 10p15, with the highest LOD score, we further studied AKR1C2, AKR1C3 and AKR1C4 involved in steroid metabolism, as well as KLF6 expressed in preputial tissue from hypospadias patients. Mutation analysis of the AKR1C3 gene showed a new mutation, c.643G>A (p.(Ala215Thr)), in a boy with penile hypospadias. This mutation is predicted to have an impact on protein function and structure and was not found in controls. Altogether, we homed in on four chromosomal regions likely to harbor genes for hypospadias. Future studies will aim for studying regulatory sequence variants in these regions. PMID:24986825

Computational analysis of molt-inhibiting hormone from selected crustaceans.

PubMed

C, Kumaraswamy Naidu; Y, Suneetha; P, Sreenivasula Reddy

2013-12-01

Molt-inhibiting hormone (MIH) is a principal endocrine hormone regulating the growth in crustaceans. In total, nine MIH peptide sequences representing members of the family Penaeidae (Penaeus monodon, Litopenaeus vannamei, Marsupenaeus japonicus), Portunidae (Portunus trituberculatus, Charybdis japonica, Charybdis feriata), Cambaridae (Procambarus bouvieri), Parastacidae (Cherax quadricarinatus) and Varunidae (Eriocheir sinensis) were selected for our study. In order to develop a structure based phylogeny, predict functionally important regions and to define stability changes upon single site mutations, the 3D structure of MIH for the crustaceans were built by using homology modeling based on the known structure of MIH from M. japonicus (1J0T). Structure based phylogeny showed a close relationship between P. bouvieri and C. japonica. ConSurf server analysis showed that the residues Cys(8), Arg(15), Cys(25), Asp(27), Cys(28), Asn(30), Arg(33), Cys(41), Cys(45), Phe(51), and Cys(54) may be functionally significant among the MIH of crustaceans. Single amino acid substitutions 'Y' and 'G' at the positions 71 and 72 of the MIH C-terminal region showed an alteration in the stability indicating that a change in this region may alter the function of MIH. In conclusion, we proposed a computational approach to analyze the structure, phylogeny and stability of MIH from crustaceans. © 2013.

Binary polymorphic cocrystals: an update on the available literature in the Cambridge Structural Database, including a new polymorph of the pharmaceutical 1:1 cocrystal theophylline-3,4-dihydroxybenzoic acid.

PubMed

Mnguni, Malitsatsi J; Michael, Joseph P; Lemmerer, Andreas

2018-06-01

An analysis and classification of the 2925 neutral binary organic cocrystals in the Cambridge Structural Database is reported, focusing specifically on those both showing polymorphism and containing an active pharmaceutical ingredient (API). The search was confined to molecules having only C, H, N, O, S and halogens atoms. It was found that 400 out of 2925 cocrystals can be classified as pharmaceutical cocrystals, containing at least one API, and that of those, 56 can be classified as being polymorphic cocrystals. In general, the total number of polymorphic cocrystal systems of any type stands at 125. In addition, a new polymorph of the pharmaceutical cocrystal theophylline-3,4-dihydroxybenzoic acid (1/1), C 7 H 8 N 4 O 2 ·C 7 H 6 O 4 , is reported.

Hydrothermal Synthesis, Crystal Structure, and Photoluminescent Properties of Li[UO2(CH3COO)3]3[Co(H2O)6

NASA Astrophysics Data System (ADS)

AlDamen, Murad A.; Juwhari, Hassan K.; Al-zuheiri, Aya M.; Alnazer, Louy A.

2017-12-01

Single crystal of Li[UO2(CH3COO)3]3[Co(H2O)6] was prepared and found to crystallize in the monoclinic crystal system in the sp. gr. C2/ c, with Z = 2, and unit cell parameters a = 22.1857(15) Å, b = 13.6477(8) Å, c = 15.6921(10) Å, β = 117.842(9)°, V = 4201.3(4) Å3. The crystal was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The single crystal X-ray diffraction analysis revealed that the crystal has a lamellar structure in which a cobalt hydrate is sandwiched within the Li[UO2(CH3COO)3]3 2- chains. Furthermore, the room temperature photoluminescence spectrum of the complex was investigated in the solid state.

Structural stability of posterior retainer design for resin-bonded prostheses: a 3D finite element study.

PubMed

Lin, Jie; Zheng, Zhiqiang; Shinya, Akikazu; Matinlinna, Jukka Pekka; Botelho, Michael George; Shinya, Akiyoshi

2015-09-01

The purpose of this in vitro study was to compare the stress distribution and natural frequency of different shape and thickness retainer designs for maxillary posterior resin-bonded prostheses using finite element (FE) method. A 3D FE model of a three unit posterior resin-bonded prosthesis analysis model was generated. Three different shaped retainer designs, viz. C-shaped (three axial surface wraparounds), D-shaped (three axial surface wraparounds with central groove) and O-shaped (360° wraparounds), and three different thicknesses, viz., 0.4, 0.8, and 1.2 mm, resin-bonded prostheses were used in this study. The resin-bonded prosthesis analysis model was imported into an FE analysis software (ANSYS 10.0, ANSYS, USA) and attribution of material properties. The nodes at the bottom surface of the roots were assigned fixed zero displacement in the three spatial dimensions. A simulated angle of 45° loading of a 100 N force was applied to the node of the pontic lingual cusp surface. The stress distributions and corresponding natural frequencies were analyzed and resolved. The C-shaped retainer for 0.4 mm thickness recorded the greatest von Mises stresses of 71.4 MPa for all three groups. C-shaped, D-shaped and O-shaped retainer presented natural frequencies 3,988, 7,754, and 10,494 Hz, respectively. D-shaped retainer and O-shaped retainer increased natural frequencies and structural rigidity over the traditional C-shaped retainer. The maximum von Mises stresses values of the remaining tooth and prosthesis decreased with greater retainer thickness. D-shaped retainer and O-shaped retainer increased natural frequencies and structural rigidity over the traditional C-shaped retainer.

Crystal structures of the ionic conductors Bi{sub 46}M{sub 8}O{sub 89} (M=P, V) related to the fluorite-type structure

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

Darriet, J.; Launay, J.C.; Zuniga, F.J.

2005-06-15

The crystal structures of the two oxides Bi{sub 46}M{sub 8}O{sub 89} (M=P, V) have been solved from single crystals X-ray data at room temperature. Bi{sub 46}P{sub 8}O{sub 89} crystallizes in the monoclinic symmetry (space group C2/m) with the cell parameters a=19.6073(4)A, b=11.4181(4)A, c=21.1119(4)A and {beta}=112.14(3){sup o}. The symmetry of Bi{sub 46}V{sub 8}O{sub 89} is also monoclinic but the space group is P2{sub 1}/c with the unit-cell parameters: a=20.0100(4)A, b=11.6445(4)A, c=20.4136(4)A and {beta}=107.27(3){sup o}. Both structures derive from an oxygen deficient fluorite-type structure where the Bi and M cations (M=P, V) are ordered in the framework. The structures are characterised bymore » isolated MO{sub 4} tetrahedra (M=P, V) which contradicts the previous results. The difference between the two structures is only due to a different order of the M atoms (M=P, V) in the fluorite-type superstructure. It will be shown that some oxygen sites are partially occupied in both structures which can explain the ion conduction properties of these phases. A structural building principle will be proposed that can explain the large domain of solid solution related to the fluorite-type observed in both systems.« less

Dysfunctional C8 beta chain in patients with C8 deficiency.

PubMed

Tschopp, J; Penea, F; Schifferli, J; Späth, P

1986-12-01

Two sera from unrelated individuals, each lacking C8 activity, were examined by Western blot analysis. Using antisera raised against whole C8, the two sera are shown to lack the C8 beta chain, indicating a C8 beta deficiency, which is frequently observed in cases of dysfunctional C8. In contrast, by means of a specific anti-C8-beta antiserum, a C8 beta-like polypeptide chain of apparently identical molecular weight compared to normal C8 beta was detected. Digestion of normal and dysfunctional C8 beta with Staphylococcus aureus V8 protease revealed distinct differences in the enzymatic digestion pattern. We conclude that the dysfunction in the C8 protein in these two patients resides in the dysfunctional C8 beta chain, and that this form of C8 deficiency is distinct from C8 deficiencies previously reported, in which one or both C8 subunits are lacking.

Hydrogen bond assisted interaction of glutamine with chromium (III) complex of 8-hydroxyquinoline: Experimental and theoretical studies

NASA Astrophysics Data System (ADS)

Narayanan, Jayanthi; Carlos-Alberto, Aguilar H.; Arturo, Lazarini M.; Höpfl, Herbert; Enrique-Fernando, Velazquez C.; Fernando, Rocha A.; Fernando-Toyohiko, Wakida K.; Velazquez-Lopez, José E.; Lesli, Arroyo O.

2018-03-01

Chromium (III) complex [Cr (hq)3;C2H5OH] of 8-hydroxyquinoline (hq) was prepared and its structure was resolved by X-ray diffraction analysis at low-temperature, showing that Cr3+ ion presents in distorted octahedral geometry, and it is consistent with the DFT optimized structure. It was observed that solvent ethanol is involved a hydrogen bond with 8-hydroxyquinoline anion. Furthermore, the molecular orbital contributions to spectral bands observed for the complex were determined by TD-DFT. The interaction of [Cr (hq)3;C2H5OH] with glutamine (Gln) or asparagine (Asn) shows that the complex binds effectively with glutamine through hydrogen bonding (H2N+-HṡṡṡOethanol) to form a possible stable adduct [Cr (hq)3;C2H5OH)Gln], yielding its binding constant 10,000 times greater (1.4315 M-1) than that for Asn (5.0 × 10-4 M-1). This is apparently due to the formation of stable secondary coordination sphere through the hydrogen bond between the metal complex with Gln. This observation is good agreement with the total molecular energy as well as with the molecular orbital study, i.e. in the DFT calculation, a lower total molecular energy (-8299,549.441 kcal/mmol) for [Cr (hq)3;C2H5OH) Gln] was obtained than that resulted for [Cr (hq)3;C2H5OH)Asn] (-8194,799.867 kcal/mmol), establishing ethanol effectively stabilizes the interaction between glutamine and the complex. Finally, antibacterial properties of [Cr (hq)3;C2H5OH] against Gram positive Bacillus cereus and Gram negative Escherichia coli was also studied, and compared its bacterial growths for its adducts of glutamine or of asparagine.

Structure and inhibition analysis of the mouse SAD-B C-terminal fragment.

PubMed

Ma, Hui; Wu, Jing-Xiang; Wang, Jue; Wang, Zhi-Xin; Wu, Jia-Wei

2016-10-01

The SAD (synapses of amphids defective) kinases, including SAD-A and SAD-B, play important roles in the regulation of neuronal development, cell cycle, and energy metabolism. Our recent study of mouse SAD-A identified a unique autoinhibitory sequence (AIS), which binds at the junction of the kinase domain (KD) and the ubiquitin-associated (UBA) domain and exerts autoregulation in cooperation with UBA. Here, we report the crystal structure of the mouse SAD-B C-terminal fragment including the AIS and the kinase-associated domain 1 (KA1) at 2.8 Å resolution. The KA1 domain is structurally conserved, while the isolated AIS sequence is highly flexible and solvent-accessible. Our biochemical studies indicated that the SAD-B AIS exerts the same autoinhibitory role as that in SAD-A. We believe that the flexible isolated AIS sequence is readily available for interaction with KD-UBA and thus inhibits SAD-B activity.

Approach to the study of flavone di-C-glycosides by high performance liquid chromatography-tandem ion trap mass spectrometry and its application to characterization of flavonoid composition in Viola yedoensis.

PubMed

Cao, Jie; Yin, Chengle; Qin, Yan; Cheng, Zhihong; Chen, Daofeng

2014-10-01

The mass spectrometric (MS) analysis of flavone di-C-glycosides has been a difficult task due to pure standards being unavailable commercially and to that the reported relative intensities of some diagnostic ions varied with MS instruments. In this study, five flavone di-C-glycoside standards from Viola yedoensis have been systematically studied by high performance liquid chromatography-electrospray ionization-tandem ion trap mass spectrometry (HPLC-ESI-IT-MS(n)) in the negative ion mode to analyze their fragmentation patterns. A new MS(2) and MS(3) hierarchical fragmentation for the identification of the sugar nature (hexoses or pentoses) at C-6 and C-8 is presented based on previously established rules of fragmentation. Here, for the first time, we report that the MS(2) and MS(3) structure-diagnostic fragments about the glycosylation types and positions are highly dependent on the configuration of the sugars at C-6 and C-8. The base peak ((0,2) X1 (0,2) X(2)(-) ion) in MS(3) spectra of di-C-glycosides could be used as a diagnostic ion for flavone aglycones. These newly proposed fragmentation behaviors have been successfully applied to the characterization of flavone di-C-glycosides found in V. yedoensis. A total of 35 flavonoid glycosides, including 1 flavone mono-C-hexoside, 2 flavone 6,8-di-C-hexosides, 11 flavone 6,8-di-C-pentosides, 13 flavone 6,8-C-hexosyl-C-pentosides, 5 acetylated flavone C-glycosides and 3 flavonol O-glycosides, were identified or tentatively identified on the base of their UV profiles, MS and MS(n) (n = 5) data, or by comparing with reference substances. Among these, the acetylated flavone C-glycosides were reported from V. yedoensis for the first time. Copyright © 2014 John Wiley & Sons, Ltd.

New C16-noriridals and formyl-monocycloiridals from the rhizomes of Iris pseudoacorus.

PubMed

Chen, Xinglong; Zhang, Xiuqiong; Geng, Changan; Li, Tianze; Chen, Jijun

2018-01-01

Four new C 16 -noriridals (1-4) and two reported C 16 -noriridals (5-6), together with two new formyl-monocycloiridals (7-8) and three known monocycloiridals (9-11) were isolated from the rhizomes of Iris pseudoacorus. Irispseudoacorins A-D (1-4) and iridojaponals A-B (5-6) were C 16 -noriridals which shared a 6/5/7 tricyclic ring system (1-2, 5-6) or 6/5 tricyclic ring system (3-4). The formyl-monocycloiridals (7-8) were detected in the crude extracts of I. pseudoacorus by LC-MS analysis which suggested they were originated from natural sources rather than artificial products during the isolation. Their structures were determined by UV, IR, extensive NMR spectra and X-ray diffraction analyses. The known monocycloiridals 9-10 displayed pronounced cytotoxic effects against five human tumor cell lines. The IC 50 values of 9 were ranging from 12.63 to 24.69μM. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba11B26O44(PO4)2(OH)6, Li9BaB15O27(CO3) and Ba3Si2B6O16

NASA Astrophysics Data System (ADS)

Heyward, Carla; McMillen, Colin D.; Kolis, Joseph

2013-07-01

Several new borate compounds, Ba11B26O44(PO4)2(OH)6 (1), Li9BaB15O27(CO3) (2), and Ba3Si2B6O16 (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P21/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17) Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO4]3- and [CO3]2- respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO4]4- groups directly bonded to the borate groups creating a B-O-Si framework.

PAMAM-Based Dendrimers with Different Alkyl Chains Self-Assemble on Silica Surfaces: Controllable Layer Structure and Molecular Aggregation.

PubMed

Zhang, Minghui; Yang, Hui; Wang, Shujuan; Zhang, Wei; Hou, Qingfeng; Guo, Donghong; Liu, Fanghui; Chen, Ting; Wu, Xu; Wang, Jinben

2018-06-20

Amphiphilic poly(amidoamine) (PAMAM) dendrimers are a well-known dendritic family due to their remarkable ability to self-assemble on solid surface. However, the relationship between molecular conformation (or adsorption kinetics) of a self-assembled layer and molecular amphiphilicity of such kind of dendrimer is still lacking, which limits the development of modulating self-assembling structures and surface functionality. With this in mind, we synthesized a series of amphiphilic PAMAM-based dendrimers, denoted as G 1 C n , with different alkyl chains ( n = 8, 12, and 16), and investigated the molecular aggregation on silica surfaces by means of quartz crystal microbalance with dissipation, atomic force microscopy, and contact angle. After rinsing, remaining adsorption amounts of G 1 C 12 were higher than those of G 1 C 8 at high concentrations, suggesting that G 1 C 12 adlayers were more stable due to the stronger intermolecular hydrophobic interactions, whereas it preferred to adopt the intramolecular hydrophobic interactions for G 1 C 16 , with low adsorption amounts and unstable adlayers. Bilayer-like structures were inferred in G 1 C 8 and G 1 C 12 adlayers with loose conformation, whereas monolayer structures were likely to exist in the sparse adsorption film of G 1 C 16 . Our results provided more detailed understanding of the effect of molecular structure on the self-assembled structures of amphiphilic dendrimers on solid surfaces, shedding light on the controlled microstructure and wettability of functional surface by modulating the length of hydrophobic chains of dendrimers and a potential application of dendrimer-substrate combinations.

Chemical synthesis, structure-activity relationship, and properties of shepherin I: a fungicidal peptide enriched in glycine-glycine-histidine motifs.

PubMed

Remuzgo, César; Oewel, Thaís S; Daffre, Sirlei; Lopes, Thiago R S; Dyszy, Fabio H; Schreier, Shirley; Machado-Santelli, Gláucia M; Teresa Machini, M

2014-11-01

Although glycine-rich antimicrobial peptides (AMPs) are found in animals and plants, very little has been reported on their chemistry, structure activity-relationship, and properties. We investigated those topics for Shepherin I (Shep I), a glycine-rich AMP with the unique amino acid sequence G(1)YGGHGGHGGHGGHGGHGGHGHGGGGHG(28). Shep I and analogues were synthesized by the solid-phase method at 60 °C using conventional heating. Purification followed by chemical characterization confirmed the products' identities and high purity. Amino acid analysis provided their peptide contents. All peptides were active against the clinically important Candida species, but ineffective against bacteria and mycelia fungi. Truncation of the N- or C-terminal portion reduced Shep I antifungal activity, the latter being more pronounced. Carboxyamidation of Shep I did not affect the activity against C. albicans or C. tropicalis, but increased activity against S. cerevisiae. Carboxyamidated analogues Shep I (3-28)a and Shep I (6-28)a were equipotent to Shep I and Shep Ia against Candida species. As with most cationic AMPs, all peptides had their activity significantly reduced in high-salt concentrations, a disadvantage that is defeated if 10 µM ZnCl2 is present. At 100 µM, the peptides were practically not hemolytic. Shep Ia also killed C. albicans MDM8 and ATCC 90028 cells. Fluo-Shep Ia, an analogue labeled with 5(6)-carboxyfluorescein, was rapidly internalized by C. albicans MDM8 cells, a salt-sensitive process dependent on metabolic energy and temperature. Altogether, such results shed light on the chemistry, structural requirements for activity, and other properties of candidacidal glycine-rich peptides. Furthermore, they show that Shep Ia may have strong potential for use in topical application.

An investigation of manganese based electrode materials for use in lithium ion batteries

NASA Astrophysics Data System (ADS)

Sengupta, Surajit

Lithium-based batteries are potential candidates to provide maximum volumetric and gravimetric energy density. One of the most attractive candidates as a cathode material for secondary lithium ion battery systems is the spinel LiMn 2O4 because it is environmentally friendly, less expensive and is capable of providing high energy density as compared to other cathode materials that are currently available. One problem associated with the spinel structure is capacity fading during multiple cycles of charge and discharge operations. This behaviour is due in part to the structural distortion during deep charge and discharge where nearly 100% of the lithium is extracted and inserted inside the spinel structure. Capacity fading can also be caused by dissolution of manganese ions in the electrolyte phase. A solution based method has been adapted for the synthesis of lithium manganese oxide, and chromium and cobalt doped mixed oxide materials using polyvinyl alcohol (PVA) as a chelating agent. It has been found from TGA/DSC analysis that at around 220°C the synthesis reaction is completed. The precursor powders obtained were annealed at different temperatures and times in the range of 250°C to 600°C and from 2 to 8 hours respectively to obtain pure spinel oxides. From X-ray analysis it has been observed that the crystallite size can be controlled in the range of approximately 6 nm to 32 nm depending on the annealing time and the temperature. The morphology of the synthesized materials consisted of submicron sized particles agglomerated with micropores inside the network structure. To observe the effect of physical properties on battery performance cyclic chronopotentiometric evaluation was conducted. It has been found with these synthesized materials that there is an increase in the 1st discharge capacity with an increase in the annealing time and the temperature at both 1C and C/5 rates. This increase is more significant when the annealing temperature is 600°C as compared to that at 250°C. This implies that an increase in particle size may improve the initial discharge capacity. It was observed that at the discharge rate of 1C, the material annealed at 600°C for 8 hours showed the best performance with respect to an average initial discharge capacity, energy density and capacity retention. However, it was found that the initial discharge capacity, the energy density and the capacity retention are poor for highly crystalline, micron sized lithium manganese oxide cathode material. (Abstract shortened by UMI.)

Structure-based engineering of alkaline α-amylase from alkaliphilic Alkalimonas amylolytica for improved thermostability.

PubMed

Deng, Zhuangmei; Yang, Haiquan; Li, Jianghua; Shin, Hyun-Dong; Du, Guocheng; Liu, Long; Chen, Jian

2014-05-01

This study aimed to improve the thermostability of alkaline α-amylase from Alkalimonas amylolytica through structure-based rational design and systems engineering of its catalytic domain. Separate engineering strategies were used to increase alkaline α-amylase thermostability: (1) replace histidine residues with leucine to stabilize the least similar region in domain B, (2) change residues (glycine, proline, and glutamine) to stabilize the highly conserved α-helices in domain A, and (3) decrease the free energy of folding predicted by the PoPMuSiC program to stabilize the overall protein structure. A total of 15 single-site mutants were obtained, and four mutants - H209L, Q226V, N302W, and P477V - showed enhanced thermostability. Combinational mutations were subsequently introduced, and the best mutant was triple mutant H209L/Q226V/P477V. Its half-life at 60 °C was 3.8-fold of that of the wild type and displayed a 3.2 °C increase in melting temperature compared with that of the wild type. Interestingly, other biochemical properties of this mutant also improved: the optimum temperature increased from 50 °C to 55 °C, the optimum pH shifted from 9.5 to 10.0, the stable pH range expanded from 7.0-11.0 to 6.0-12.0, the specific activity increased by 24 %, and the catalytic efficiency (k cat/K m) increased from 1.8×10(4) to 3.5 × 10(4) l/(g min). Finally, the mechanisms responsible for the increased thermostability were analyzed through comparative analysis of structure models. The structure-based rational design and systems engineering strategies in this study may also improve the thermostability of other industrial enzymes.

LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

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

Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

2002-03-31

This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. This period has continued to address the problem of making dense 1/2 to 5 {micro}m thick dense layers on porous substrates (the cathode LSM). Our current status is that we are making structures of 2-5 cm{sup 2} in area, which consist of either dense YSZ or CGO infiltrated into a 2-5 {micro}m thick 50% porous layer made of either nanoncrystalline CGO or YSZ powder. This composite structure coats a macroporous cathode or anode; which serves asmore » the structural element of the bi-layer structure. These structures are being tested as SOFC elements. A number of structures have been evaluated both as symmetrical and as button cell configuration. Results of this testing indicates that the cathodes contribute the most to cell losses for temperatures below 750 C. In this investigation different cathode materials were studied using impedance spectroscopy of symmetric cells and IV characteristics of anode supported fuel cells. Cathode materials studied included La{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF), La{sub 0.7}Sr{sub 0.2}MnO{sub 3} (LSM), Pr{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}O{sub 3} (PSCF), Sm{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF), and Yb{sub .8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF). A new technique for filtering the Fourier transform of impedance data was used to increase the sensitivity of impedance analysis. By creating a filter specifically for impedance spectroscopy the resolution was increased. The filter was tailored to look for specific circuit elements like R//C, Warburg, or constant phase elements. As many as four peaks can be resolved using the filtering technique on symmetric cells. It may be possible to relate the different peaks to material parameters, like the oxygen exchange coefficient. The cathode grouped in order from lowest to highest ASR is LSCF < PSCF < SSCF < YSCF < LSM. The button cell results agree with this ordering indicating that this is an important tool for use in developing our understanding of electrode behavior in fuel cells.« less

Effects of C/N ratio on nitrous oxide production from nitrification in a laboratory-scale biological aerated filter reactor.

PubMed

He, Qiang; Zhu, Yinying; Fan, Leilei; Ai, Hainan; Huangfu, Xiaoliu; Chen, Mei

2017-03-01

Emission of nitrous oxide (N 2 O) during biological wastewater treatment is of growing concern. This paper reports findings of the effects of carbon/nitrogen (C/N) ratio on N 2 O production rates in a laboratory-scale biological aerated filter (BAF) reactor, focusing on the biofilm during nitrification. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and microelectrode technology were utilized to evaluate the mechanisms associated with N 2 O production during wastewater treatment using BAF. Results indicated that the ability of N 2 O emission in biofilm at C/N ratio of 2 was much stronger than at C/N ratios of 5 and 8. PCR-DGGE analysis showed that the microbial community structures differed completely after the acclimatization at tested C/N ratios (i.e., 2, 5, and 8). Measurements of critical parameters including dissolved oxygen, oxidation reduction potential, NH 4 + -N, NO 3 - -N, and NO 2 - -N also demonstrated that the internal micro-environment of the biofilm benefit N 2 O production. DNA analysis showed that Proteobacteria comprised the majority of the bacteria, which might mainly result in N 2 O emission. Based on these results, C/N ratio is one of the parameters that play an important role in the N 2 O emission from the BAF reactors during nitrification.

Enrichment of peptides in serum by C(8)-functionalized magnetic nanoparticles for direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis.

PubMed

Yao, Ning; Chen, Hemei; Lin, Huaqing; Deng, Chunhui; Zhang, Xiangmin

2008-03-21

Human serum contains a complex array of proteolytically derived peptides (serum peptidome), which contain biomarkers of preclinical screening and disease diagnosis. Recently, commercial C(8)-functionalized magnetic beads (1-10 microm) were widely applied to the separation and enrichment of peptides in human serum, prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. In this work, laboratory-prepared C(8)-functionalized magnetic nanoparticles (about 50 nm) were prepared and applied to the fast separation and the enrichment of peptides from serum. At first, the C(8)-magnetic nanoparticles were synthesized by modifying amine-functionalized magnetic nanoparticles with chlorodimethyloctylsilane. These synthesized C(8)-amine-functionalized magnetic particles have excellent magnetic responsibility, high dispersibility and large surface area. Finally, the C(8)-magnetic nanoparticles were successfully applied to fast and efficient enrichment of low-abundance peptides from protein tryptic digestion and human serum followed by MALDI-TOF-MS analysis.

Superconductivity in layered ZrP2-x Se x with PbFCl-type structure

NASA Astrophysics Data System (ADS)

Ishida, Shigeyuki; Fujihisa, Hiroshi; Hase, Izumi; Yanagi, Yousuke; Kawashima, Kenji; Oka, Kunihiko; Gotoh, Yoshito; Yoshida, Yoshiyuki; Iyo, Akira; Eisaki, Hiroshi; Kito, Hijiri

2016-05-01

We performed a systematic study of the crystal structure, physical properties, and electronic structure of PbFCl-type ZrP2-x Se x (0.3 ≤ x ≤ 0.9). We successfully synthesized single-phase polycrystalline samples for the Se substitution range of 0.4 ≤ x ≤ 0.8. The crystal structure of the compound is characterized by the alternate stacking of a two-dimensional P square net and a Zr-(P1-x Se x ) network. ZrP2-x Se x exhibits a dome-like superconductivity phase diagram and has a maximum superconducting transition temperature (T c) of 6.3 K for x ≈ 0.6. Resistivity and Hall measurements indicated that electron-phonon scattering plays a dominant role and that electron-type carriers dominate charge transport. Specific heat measurements confirmed that ZrP2-x Se x exhibits bulk superconductivity. Further, the value of the specific heat jump at T c (ΔC/γT c ≈ 1.35) is in keeping with the BCS weak-coupling model. These facts suggest a rather conventional pairing mechanism in ZrP2-x Se x . The x dependence of T c can be explained on the basis of the density of states (DOS) for x ≤ 0.7, whereas the decrease in T c with an increase in the DOS for x = 0.8 needs further investigation. One possible reason for the suppression of superconductivity is that the PbFCl-type structure becomes unstable for x ≥ 0.8. The results of electronic structure calculations agree reasonably well with those of the experimental observations, suggesting that the Zrd band plays a primary role in determining the physical properties. Further, the calculations predict a significant change in the Fermi-surface topology for x ≥ 0.8 this is a probable reason for the decrease in T c as well as the instability of the PbFCl-type structure.

Crystallization and preliminary X-ray crystallographic analysis of BxlA, an intracellular beta-D-xylosidase from Streptomyces thermoviolaceus OPC-520.

PubMed

Morioka, Hideaki; Miki, Yasuhiro; Saito, Kei; Tomoo, Koji; Ishida, Toshimasa; Hasegawa, Tomokazu; Yamano, Akihito; Takada, Chiaki; Miyamoto, Katsushiro; Tsujibo, Hiroshi

2010-07-01

BxlA from Streptomyces thermoviolaceus OPC-520, together with the extracellular BxlE and the integral membrane proteins BxlF and BxlG, constitutes a xylanolytic system that participates in the intracellular transport of xylan-degradation products and the production of xylose. To elucidate the mechanism of the hydrolytic degradation of xylooligosaccharides to xylose at the atomic level, X-ray structural analysis of BxlA was attempted. The recombinant BxlA protein (molecular weight 82 kDa) was crystallized by the hanging-drop vapour-diffusion method at 289 K. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 142.2, b = 129.5, c = 101.4 A, beta = 119.8 degrees , and contained two molecules per asymmetric unit (V(M) = 2.47 A(3) Da(-1)). Diffraction data were collected to a resolution to 2.50 A and provided a data set with an overall R(merge) of 8.3%.

Characterizing a partially ordered miniprotein through folding molecular dynamics simulations: Comparison with the experimental data.

PubMed

Baltzis, Athanasios S; Glykos, Nicholas M

2016-03-01

The villin headpiece helical subdomain (HP36) is one of the best known model systems for computational studies of fast-folding all-α miniproteins. HP21 is a peptide fragment-derived from HP36-comprising only the first and second helices of the full domain. Experimental studies showed that although HP21 is mostly unfolded in solution, it does maintain some persistent native-like structure as indicated by the analysis of NMR-derived chemical shifts. Here we compare the experimental data for HP21 with the results obtained from a 15-μs long folding molecular dynamics simulation performed in explicit water and with full electrostatics. We find that the simulation is in good agreement with the experiment and faithfully reproduces the major experimental findings, namely that (a) HP21 is disordered in solution with <10% of the trajectory corresponding to transiently stable structures, (b) the most highly populated conformer is a native-like structure with an RMSD from the corresponding portion of the HP36 crystal structure of <1 Å, (c) the simulation-derived chemical shifts-over the whole length of the trajectory-are in reasonable agreement with the experiment giving reduced χ(2) values of 1.6, 1.4, and 0.8 for the Δδ(13) C(α) , Δδ(13) CO, and Δδ(13) C(β) secondary shifts, respectively (becoming 0.8, 0.7, and 0.3 when only the major peptide conformer is considered), and finally, (d) the secondary structure propensity scores are in very good agreement with the experiment and clearly indicate the higher stability of the first helix. We conclude that folding molecular dynamics simulations can be a useful tool for the structural characterization of even marginally stable peptides. © 2015 The Protein Society.

Structure of 8B from elastic and inelastic 7Be+p scattering

NASA Astrophysics Data System (ADS)

Mitchell, J. P.; Rogachev, G. V.; Johnson, E. D.; Baby, L. T.; Kemper, K. W.; Moro, A. M.; Peplowski, P.; Volya, A. S.; Wiedenhöver, I.

2013-05-01

Background: Detailed experimental knowledge of the level structure of light weakly bound nuclei is necessary to guide the development of new theoretical approaches that combine nuclear structure with reaction dynamics.Purpose: The resonant structure of 8B is studied in this work.Method: Excitation functions for elastic and inelastic 7Be+p scattering were measured using a 7Be rare isotope beam. Excitation energies ranging between 1.6 and 3.4 MeV were investigated. An R-matrix analysis of the excitation functions was performed.Results: New low-lying resonances at 1.9, 2.54, and 3.3 MeV in 8B are reported with spin-parity assignment 0+, 2+, and 1+, respectively. Comparison to the time-dependent continuum shell (TDCSM) model and ab initio no-core shell model/resonating-group method (NCSM/RGM) calculations is performed. This work is a more detailed analysis of the data first published as a Rapid Communication. J. P. Mitchell, G. V. Rogachev, E. D. Johnson, L. T. Baby, K. W. Kemper , [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.82.011601 82, 011601(R) (2010)].Conclusions: Identification of the 0+, 2+, 1+ states that were predicted by some models at relatively low energy but never observed experimentally is an important step toward understanding the structure of 8B. Their identification was aided by having both elastic and inelastic scattering data. Direct comparison of the cross sections and phase shifts predicted by the TDCSM and ab initio no-core shell model coupled with the resonating group method is of particular interest and provides a good test for these theoretical approaches.

Cu3Mo2O9: An Ultralow-Firing Microwave Dielectric Ceramic with Good Temperature Stability and Chemical Compatibility with Aluminum

NASA Astrophysics Data System (ADS)

Wen, Wangxi; Li, Chunchun; Sun, Yihua; Tang, Ying; Fang, Liang

2018-02-01

An ultralow-firing microwave dielectric ceramic Cu3Mo2O9 with orthorhombic structure has been fabricated via a solid-state reaction method. X-ray diffraction analysis, Rietveld refinement, Raman spectroscopy, energy-dispersive spectrometry, and scanning electron microscopy were employed to explore the phase purity, crystal structure, and microstructure. Pure and dense Cu3Mo2O9 ceramics could be obtained in the sintering temperature range from 580°C to 680°C. The sample sintered at 660°C for 4 h exhibited the highest relative density (˜ 97.2%) and best microwave dielectric properties with ɛ r = 7.2, Q × f = 19,300 GHz, and τ f = - 7.8 ppm/°C. Chemical compatibility with aluminum electrodes was also confirmed. All the results suggest that Cu3Mo2O9 ceramic is a promising candidate for use in ultralow-temperature cofired ceramic applications.

The Structure and Mechanical Properties of Ni-Mo PM Steels with Addition of Mn And Cu

NASA Astrophysics Data System (ADS)

Lichańska, E.; Kulecki, P.; Pańcikiewicz, K.

2017-12-01

The aim of the study was to evaluate the effect of chemical composition on the structure and mechanical properties of Mn-Ni-Mo and Ni-Mo-Cu PM steels. Pre-alloyed powder Astaloy 85Mo, diffusion alloyed powders Distaloy AQ and Distaloy AB produced by Höganäs, low carbon ferromanganese, carbonyl nickel powder T255 with three-dimensional filamentary structure and graphite CU-F have been used as the basic powders. Three mixtures with compositions of Fe-1%Mn-(0.5/1.75)%Ni-(0.5/0.85)%Mo-0.8%C and Fe-1.75%Ni-0.5%Mo-1.5%Cu-0.8%C were prepared in a Turbula mixer. Green compacts were single pressed in a steel die at 660 MPa according to PN-EN ISO 2740 standard. Sinterhardening was carried out at 1250°C in a mixture of 95% N2+5% H2 for 60 minutes. Mechanical tests (tensile, bend, hardness) and microstructural investigations were performed. Additionally, XRD and EDS analysis, fractographic investigations were carried out. The microstructures of steels investigated were mainly bainitic or bainitic-martensitic. Addition 1% Mn to Distaloy AQ based steel caused increase of tensile properties (YS from 422 to 489 MPa, UTS from 522 to 638 MPa, TRS from 901 to 1096 MPa) and decrease of plasticity (elongation from 3.65 to 2.84%).

Enhancing the superconducting temperature of MgB2 by SWCNT dilution

NASA Astrophysics Data System (ADS)

Ma, Danhao; Jayasingha, Ruwantha; Hess, Dustin T.; Adu, Kofi W.; Sumanasekera, Gamini U.; Terrones, Mauricio

2014-02-01

We report, for the first time, an increase in the superconducting critical temperature, TC of commercial “dirty” MgB2 by a nonsubstitutional hole-doping of the MgB2 structure using minute, single-wall carbon nanotube (SWCNT) inclusions. We varied the SWCNTs concentration from 0.05 wt% to 5 wt% and investigated the temperature-dependent resistivity from 10 K to 300 K. We used micro-Raman spectroscopy, field-emission scanning electron microscopy, and X-ray diffraction to analyze the interfacial interactions between the SWCNTs and the MgB2 grains. We obtained an increase in TC from 33.0 to 37.8 K (ΔTC+=4.8 K), which is attributed to charge transfer from the MgB2 structure to the SWCNT structure. The charge transfer phenomenon is confirmed by micro-Raman analysis of the phonon states of the SWCNT tangential band frequency in the composites. We determined the charge transfer per carbon atom to be 0.0023/C, 0.0018/C and 0.0008/C for 0.05 wt%, 0.5 wt% and 5 wt% SWCNT inclusions, respectively, taking into account the contributions from the softening of the lattice constant and the nonadiabatic (dynamic) effects at the Fermi level. This report provides an experimental, alternative pathway to hole-doping of MgB2 without appealing to chemical substitution.

Ab initio/GIAO-CCSD(T) (13)C NMR study of the rearrangement and dynamic aspects of rapidly equilibrating tertiary carbocations, C6H13(+) and C7H15(+).

PubMed

Olah, George A; Prakash, G K Surya; Rasul, Golam

2016-01-05

The rearrangement pathways of the equilibrating tertiary carbocations, 2,3-dimethyl-2-butyl cation (C6H13(+), 1), 2,3,3-trimethyl-2-butyl cation (C7H15(+), 5) and 2,3-dimethyl-2-pentyl cation (C7H15(+), 8 and 9) were investigated using the ab initio/GIAO-CCSD(T) (13)C NMR method. Comparing the calculated and experimental (13)C NMR chemical shifts of a series of carbocations indicates that excellent prediction of δ(13)C could be achieved through scaling. In the case of symmetrical equilibrating cations (1 and 5) the Wagner-Meerwein 1,2-hydride and 1,2-methide shifts, respectively, produce the same structure. This indicates that the overall (13)C NMR chemical shifts are conserved and independent of temperature. However, in the case of unsymmetrical equilibrating cations (8 and 9) the Wagner-Meerwein shift produces different tertiary structures, which have slightly different thermodynamic stabilities and, thus, different spectra. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level structure 8 is only 90 calories/mol more stable than structure 9. Based on computed (13)C NMR chemical shift calculations, mole fractions of these isomers were determined by assuming the observed chemical shifts are due to the weighted average of the chemical shifts of the static ions. © 2015 Wiley Periodicals, Inc.

CaB2 S4 O16 : A Borosulfate Exhibiting a New Structure Type with Phyllosilicate Analogue Topology.

PubMed

Bruns, Jörn; Podewitz, Maren; Schauperl, Michael; Joachim, Bastian; Liedl, Klaus R; Huppertz, Hubert

2017-11-27

The reaction of Ca(CO 3 ) with H 3 BO 3 in oleum (20 % SO 3 ) yielded colorless single-crystals of CaB 2 S 4 O 16 (monoclinic, P2 1 /c, a=5.5188(2), b=15.1288(6), c=13.2660(6) Å, β=92.88(1)°, V=1106.22(8) Å 3 ). X-ray single-crystal structure analysis revealed a phyllosilicate-analogue anionic sub-structure, forming 2D infinite anionic layers, which exhibit an unprecedented arrangement of condensed twelve-membered (zwölfer) and four-membered (vierer) rings of corner-shared (SO 4 ) and (BO 4 ) tetrahedra. Charge compensation is achieved by Ca 2+ cations, residing exclusively above the centers of the twelve-membered rings. DFT investigations on the solid-state structure corroborate the experimental findings and allow for a detailed valuation of charge distribution within the anionic network and an assignment of vibrational frequencies. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and structural study of 4-(2-chlorophenyl)-2-ethoxy-5,6,7,8,9,10-hexahydrocycloocta[B] pyridine-3-carbonitrile

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

Fathima, K. Saiadali; Vasumathi, M.; Anitha, K., E-mail: singlecrystalxrd@gmail.com

2016-05-23

The novel organic material C{sub 20}H{sub 21}ClN{sub 2}O was synthesized by One-Pot synthesis method and the single crystals were grown by slow evaporation solution growth technique. The crystal structure was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R=0.039 for 2746 reflections. Crystal system of the grown crystal was found to be monoclinic with the space group P2{sub 1}/a and a=9.196(4) Å, b=13.449(4) Å, c=14.818(4) Å, β= 101.542(3)°, V=1795.6(11) Å{sup 3} and Z=4. In this crystal structure, cyclooctanone prefers to reside in a chair-boat conformation. Themore » structure is stabilized by attractive molecular force such as CH/π interaction called hydrophobic interaction.« less

Structure-function analysis of the extracellular domains of the Duffy antigen/receptor for chemokines: characterization of antibody and chemokine binding sites.

PubMed

Tournamille, Christophe; Filipe, Anne; Wasniowska, Kazimiera; Gane, Pierre; Lisowska, Elwira; Cartron, Jean-Pierre; Colin, Yves; Le Van Kim, Caroline

2003-09-01

The Duffy antigen/receptor for chemokines (DARC), a seven-transmembrane glycoprotein carrying the Duffy (Fy) blood group, acts as a widely expressed promiscuous chemokine receptor. In a structure-function study, we analysed the binding of chemokines and anti-Fy monoclonal antibodies (mAbs) to K562 cells expressing 39 mutant forms of DARC with alanine substitutions spread out on the four extracellular domains (ECDs). Using synthetic peptides, we defined previously the Fy6 epitope (22-FEDVW-26), and we characterized the Fya epitope as the linear sequence 41-YGANLE-46. In agreement with these results, mutations of F22-E23, V25 and Y41, G42, N44, L45 on ECD1 abolished the binding of anti-Fy6 and anti-Fya mAbs to K562 cells respectively, Anti-Fy3 binding was abolished by D58-D59 (ECD1), R124 (ECD2), D263 and D283 (ECD4) substitutions. Mutations of C51 (ECD1), C129 (ECD2), C195 (ECD3) and C276 (ECD4 severely reduced anti-Fy3 and CXC-chemokine ligand 8 (CXCL-8) binding. CXCL-8 binding was also abrogated by mutations of F22-E23, P50 (ECD1) and D263, R267, D283 (ECD4). These results defined the Fya epitope and suggested that (1) two disulphide bridges are involved in the creation of an active chemokine binding pocket; (2) a limited number of amino acids in ECDs 1-4 participate in CXCL-8 binding; and (3) Fy3 is a conformation-dependent epitope involving all ECDs. We also showed that N-glycosylation of DARC occurred on N16SS and did not influence antibody and chemokine binding.

Metabolites from the Endophytic Fungus Curvularia sp. M12 Act as Motility Inhibitors against Phytophthora capsici Zoospores.

PubMed

Mondol, Muhammad Abdul Mojid; Farthouse, Jannatul; Islam, Mohammad Tofazzal; Schüffler, Anja; Laatsch, Hartmut

2017-02-24

The endophytic fungus Curvularia sp., strain M12, was isolated from a leaf of the medicinal plant Murraya koenigii and cultured on rice medium followed by chemical screening of the culture extract. Chromatographic analysis led to the isolation of four new compounds, murranofuran A (1), murranolide A (2), murranopyrone (3a), and murranoic acid A (4a), along with six known metabolites, N-(2-hydroxy-6-methoxyphenyl)acetamide (5), curvularin (6), (S)-dehydrocurvularin (7), pyrenolide A (8), modiolide A (9), and 8-hydroxy-6-methoxy-3-methylisocoumarin (10). The structures of the known compounds were confirmed by comparing ESI HR mass spectra, 1 H and 13 C NMR, and optical rotation data with values reported in the literature. The planar structures of the new compounds were elucidated by extensive analysis of 1D and 2D NMR and mass data. The absolute configurations of the new compounds were established by coupling constant analysis, modified Mosher's method, and CD data. Compound 8 showed a strong motility impairing activity against Phytophthora capsici zoospores at a low concentration (100% at 0.5 μg/mL) in a short time (30 min). Compounds 2, 3a, 6, 7, 9, and 10 exhibited zoospore motility impairment activity at higher concentrations (IC 50 : 50-100 μg/mL).

Understanding the conformational changes and molecular structure of furoyl thioureas upon substitution

NASA Astrophysics Data System (ADS)

Cairo, Raúl Ramos; Stevens, Ana María Plutín; de Oliveira, Tamires Donizeth; Batista, Alzir A.; Castellano, Eduardo E.; Duque, Julio; Soria, Delia B.; Fantoni, Adolfo C.; Corrêa, Rodrigo S.; Erben, Mauricio F.

2017-04-01

1-Acyl thioureas [R1C(O)NHC(S)NR2R3] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R1 = 2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, 1H and 13C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans-cis geometry of the almost planar thiourea unit is stabilized by intramolecular Nsbnd H ⋯ Odbnd C hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31 + G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular Nsbnd H ⋯ Sdbnd C hydrogen bond forming R22(8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S ⋯ H, O ⋯ H and H ⋯ H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.

Identification of new diterpene esters from green Arabica coffee beans, and their platelet aggregation accelerating activities.

PubMed

Wang, Xia; Meng, QianQian; Peng, XingRong; Hu, GuiLin; Qiu, MingHua

2018-10-15

Eight new ent-kaurane diterpene fatty acid esters, namely caffarolides A-H (1-8), were isolated from green beans of Coffea arabica. Their chemical structures were confirmed by extensive spectroscopic analysis including 1D, 2D NMR (HSQC, HMBC, 1 H- 1 H COSY, and ROESY), HRMS, IR and CD spectra and by GC-FID analysis. Interestingly, the diterpene moiety of these new compounds first occurred in genus Coffea. All the isolates were evaluated for platelet aggregation activity in vitro. As the results, caffarolides C, D and F (3, 4 and 6) showed induction effect for platelet aggregation and the possible structure-activity relationships have been discussed briefly. Copyright © 2018 Elsevier Ltd. All rights reserved.

Crystal structure, thermochromic and magnetic properties of organic-inorganic hybrid compound: (C7H7N2S)2CuCl4

NASA Astrophysics Data System (ADS)

Vishwakarma, Ashok K.; Kumari, Reema; Ghalsasi, Prasanna S.; Arulsamy, Navamoney

2017-08-01

The synthesis, thermal analysis, crystal structure and magnetic properties of (2-aminobenzothiazolium)2CuCl4, organic-inorganic hybrid compound, have been described. The compound crystallizes in the monoclinic space group P21/c with two formula units in a unit cell of dimensions a = 6.9522(4) Å, b = 9.6979(4) Å, c = 13.9633(6) Å, β = 97.849(3)° and volume 930.83(8) Å3 at 150(2) K. The structure consists of isolated nearly square planer [CuC14]2- units, with somewhat longer than normal Cusbnd Cl bond lengths [Cusbnd Cl (average) = 2.2711 Å]. The magnetic measurements of (2-aminobenzothiazolium)2CuCl4 using SQUID magnetometer show paramagnetic nature of the compound. Thermal measurements (TG-DTA and DSC) on this compound showed reversible phase transition at 83 °C. This transition is accompanied by the reversible change in colour of the prismatic crystal from green to dark brown, thermochromic behaviour. Temperature dependent EPR measurements on powdered sample ascertain change in coordination sphere around Cu(II) with shift in g|| = 2.150 and g⊥ = 2.071 at room temperature, typical of square planar, to g|| = 2.201 and g⊥ = 2.182 at 170 °C, typical of distorted tetrahedral geometry.

Combined neutron and synchrotron X-ray diffraction study of Sr/Mg-doped lanthanum gallates up to high temperatures

NASA Astrophysics Data System (ADS)

Guenter, M. M.; Lerch, M.; Boysen, H.; Toebbens, D.; Suard, E.; Baehtz, C.

2006-08-01

Combined neutron diffraction and high-resolution synchrotron X-ray powder diffraction methods have been used to examine the crystal structures of two sample sets of Sr/Mg-doped Lanthanum gallate with the compositions La0.9Sr0.1Ga1-yMgyO3-0.5(0.1+y) (y=0, 0.1, 0.2) and La0.8Sr0.2Ga1-yMgyO3-0.5(0.2+y) (y=0.15, 0.2) up to 900 °C. At room temperature all samples of the first series exhibit orthorhombic structures with space group Imma: La0.9Sr0.1GaO2.95: a=5.4904(1)Å, b=7.7757(1)Å, c=5.5229(1)Å; La0.9Sr0.1Ga0.9Mg0.1O2.9: a=5.5100(1)Å, b=7.8080(1)Å, c=5.5411(1)Å; La0.9Sr0.1Ga0.8Mg0.2O2.85: a=5.5269(1)Å, b=7.8318(2)Å, c=5.5459(1)Å. The samples of the second series have the cubic perovskite structure with space group Pm3¯m at room temperature: La0.8Sr0.2Ga0.85Mg0.15O2.825: a=3.9160(1)Å; La0.8Sr0.2Ga0.8Mg0.20O2.80: a=3.9195(1)Å. Samples of the first series transform from the orthorhombic to a rhombohedral (Imma→R3¯c) structure at ˜170 °C for La0.9Sr0.1GaO2.95, at ˜430 °C for La0.9Sr0.1Ga0.9Mg0.1O2.9, and between 600 and 700 °C for La0.9Sr0.1Ga0.8Mg0.2O2.85. Both La0.8Sr0.2Ga0.85Mg0.15O2.825 and La0.8Sr0.2Ga0.8Mg0.2 show no structural deviations from the cubic aristotype over the whole temperature range. The room temperature Imma structures of the first series are justified by a domain model and are rationalized in terms of static disorder increasing with Mg content, thus driving the phase transition temperatures to higher values in agreement with tolerance factor considerations. The distortion of the rhombohedral high-temperature phases (octahedra tilting and compression) and the effect of phase transitions on the ionic conductivity are discussed.

Structure and Electrical-Transport Relations in Ba(Zr,Pr)O3-δ Perovskites.

PubMed

Antunes, Isabel; Amador, Ulises; Alves, Adriana; Correia, Maria Rosário; Ritter, Clemens; Frade, Jorge Ribeiro; Pérez-Coll, Domingo; Mather, Glenn C; Fagg, Duncan Paul

2017-08-07

Members of the perovskite solid solution BaZr 1-x Pr x O 3-δ (0.2 ≤ x ≤ 0.8) with potential high-temperature electrochemical applications were synthesized via mechanical activation and high-temperature annealing at 1250 °C. Structural properties were examined by Rietveld analysis of neutron powder diffraction and Raman spectroscopy at room temperature, indicating rhombohedral symmetry (space group R3̅c) for members x = 0.2 and 0.4 and orthorhombic symmetry (Imma) for x = 0.6 and 0.8. The sequence of phase transitions for the complete solid solution from BaZrO 3 to BaPrO 3 is Pm3̅m → R3̅c → Imma → Pnma. The structural data indicate that Pr principally exists as Pr 4+ on the B site and that oxygen content increases with higher Pr content. Electrical-conductivity measurements in the temperature range of 250-900 °C in dry and humidified (pH 2 O ≈ 0.03 atm) N 2 and O 2 atmospheres revealed an increase of total conductivity by over 2 orders of magnitude in dry conditions from x = 0.2 to x = 0.8 (σ ≈ 0.08 S cm -1 at 920 °C in dry O 2 for x = 0.8). The conductivity for Pr contents x > 0.2 is attributable to positively charged electronic carriers, whereas for x = 0.2 transport in dry conditions is n-type. The change in conduction mechanism with composition is proposed to arise from the compensation regime for minor amounts of BaO loss changing from predominantly partitioning of Pr on the A site to vacancy formation with increasing Pr content. Conductivity is lower in wet conditions for x > 0.2 indicating that the positive defects are, to a large extent, charge compensated by less mobile protonic species. In contrast, the transport mechanism of the Zr-rich composition (x = 0.2), with much lower electronic conductivity, is essentially independent of moisture content.

Structural studies on Pax-8 Prd domain/DNA complex.

PubMed

Campagnolo, M; Pesaresi, A; Zelezetsky, I; Geremia, S; Randaccio, L; Bisca, A; Tell, G

2007-04-01

Pax-8 is a member of the Pax family of transcription factors and is essential in the development of thyroid follicular cells. Pax-8 has two DNA-binding domains: the paired domain and the homeo domain. In this study, a preliminary X-ray diffraction analysis of the mammalian Pax-8 paired domain in complex with the C-site of the thyroglobulin promoter was achieved. The Pax-8 paired domain was crystallized by the hanging-drop vapor-diffusion method in complex with both a blunt-ended 26 bp DNA fragment and with a sticky-ended 24 bp DNA fragment with two additional overhanging bases. Crystallization experiments make clear that the growth of transparent crystals with large dimensions and regular shape is particularly influenced by ionic strength. The crystals of Pax-8 complex with blunt-ended and sticky-ended DNA, diffracted synchrotron radiation to 6.0 and 8.0 A resolution and belongs both to the C centered monoclinic system with cell dimensions: a = 89.88 A, b = 80.05 A, c = 67.73 A, and beta = 124.3 degrees and a = 256.56, b = 69.07, c = 99.32 A, and beta = 98.1 degrees , respectively. Fluorescence experiments suggest that the crystalline disorder, deduced by the poor diffraction, can be attributed to the low homogeneity of the protein-DNA sample. The theoretical comparative model of the Pax-8 paired domain complexed with the C-site of the thyroglobulin promoter shows the probable presence of some specific protein-DNA interactions already observed in other Pax proteins and the important role of the cysteine residues of PAI subdomain in the redox control of the DNA recognition.

Assembly of a new inorganic-organic frameworks based on [Sb4Mo12(OH)6O48]10- polyanion

NASA Astrophysics Data System (ADS)

Thabet, Safa; Ayed, Meriem; Ayed, Brahim; Haddad, Amor

2014-10-01

A new organic-inorganic hybrid material, (C4N2H7)8[K(H2O)]2[Sb4Mo12(OH)6O48]ṡ16H2O (1) has been isolated by the conventional solution method and characterized by elemental analysis, single-crystal X-ray diffraction, infrared spectroscopy, UV-visible spectroscopies, cyclic voltammetry and TG-DTA analysis. The compound crystallizes in the triclinic space group P - 1 with a = 13.407(6) Å, b = 13.906(2) Å, c = 14.657(7) Å, α = 77.216(9)°, β = 71.284(6)°, γ = 71.312(3)° and Z = 1. The crystal structure exhibits an infinite 1D inorganic structure built from [Sb4Mo12(OH)6O48]10- clusters and potassium cations; adjacent chains are further joined up hydrogen bonding interactions between protonated 2-methylimidazolim cations, water molecules and polyoxoanions to form a 3D supramolecular architecture.

Determination of Trophic Structure in Selected Freshwater Ecosystems by using Stable Isotope Analysis

PubMed Central

Zainordin, ‘Amila Faqhira; Ab Hamid, Suhaila

2017-01-01

Stable isotope analysis has been used extensively to establish trophic relationships in many ecosystems. Present study utilised stable isotope signatures of carbon and nitrogen to identify trophic structure of aquatic food web in river and rice field ecosystems in Perak, northern peninsular Malaysia. The mean δ13C values of all producers ranged from −35.29 ± 0.21 to −26.00 ± 0.050‰. The greatest δ15N values noted was in zenarchopterid fish with 9.68 ± 0.020‰. The δ15N values of aquatic insects ranged between 2.59 ± 0.107 in Elmidae (Coleoptera) and 8.11 ± 0.022‰ in Nepidae (Hemiptera). Correspondingly, with all the δ13C and δ15N values recorded, it can be deduced that there are four trophic levels existed in the freshwater ecosystems which started with the producer (plants), followed by primary consumer (aquatic insects and non-predatory fish), secondary consumer (invertebrate predators) and lastly tertiary consumer (vertebrate predators). PMID:28890758

Synthesis, crystal structure and DFT studies of N-(4-acetyl-5,5-dimethyl-4,5-dihydro-1,3,4-thiadiazol-2-yl)acetamide

NASA Astrophysics Data System (ADS)

Gautam, P.; Gautam, D.; Chaudhary, R. P.

2013-12-01

The title compound N-(4-acetyl-5,5-dimethyl-4,5-dihydro-1,3,4-thiadiazol-2-yl)acetamide ( III) was obtained from the reaction of 2-(propan-2-ylidene)hydrazinecarbothioamide ( II) with acetic anhydride instead of formation of the desired thiosemcarbazide derivative of Meldrum acid. The structures of II and III were established by elemental analysis, IR, NMR, Mass and X-ray crystallographic studies. II crystallizes in triclinic system, sp. gr. Z = 2; III crystallizes in the monoclinic system, sp. gr. P21/ c, Z = 8. Density functional theory (DFT) calculations have been carried out for III. 1H and 13C NMR of III has been calculated and correlated with experimental results.

Synthesis and structural analysis of Fe doped TiO2 nanoparticles using Williamson Hall and Scherer Model

NASA Astrophysics Data System (ADS)

Patle, L. B.; Labhane, P. K.; Huse, V. R.; Gaikwad, K. D.; Chaudhari, A. L.

2018-05-01

The nanoparticles of Pure and doped Ti1-xFexO were synthesized by modified co-precipitation method successfully with nominal composite of x=0.0, 0.01, 0.03 and 0.05 at room temperature. The precursors were further calcined at 500°C for 6hrs in muffle furnace which results in the formation of different TiO2 phase compositions. The structural analysis carried out by XRD (Bruker D8 Cu-Kα1). X-ray peak broadening analysis was used to evaluate the crystalline sizes, the lattice parameters, atomic packing fraction, c/a ratio, X-ray density and Volume of unit cell. The Williamson Hall analysis is used to find grain size and Strain of prepared TiO2 nano particles. Crystalline TiO2 with a Tetragonal Anatase phase is confirmed by XRD results. The grain size of pure and Fe doped samples were found in the range of 10nm to 18nm. All the physical parameters of anatase tetragonal TiO2 nanoparticles were calculated more precisely using modified W-H plot a uniform deformation model (UDM). The results calculated from both the techniques were approximately similar.

Effect of calcination temperature on structure and photocatalytic activity under UV and visible light of nanosheets from low-cost magnetic leucoxene mineral

NASA Astrophysics Data System (ADS)

Charerntanom, Wissanu; Pecharapa, Wisanu; Pavasupree, Suttipan; Pavasupree, Sorapong

2017-07-01

This research has experimentally synthesized the nanosheets from the naturally-mineral magnetic leucoxene under the hydrothermal synthesis condition of 105 °C for 24 h. Magnetic leucoxene was utilized as the starting material due to its high TiO2 content (70-80%) and inexpensiveness. The characterization of the synthesized nanosheets was subsequently carried out: the crystalline structure, the chemical composition, the shape, the size and the specific surface area, by the X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) specific surface area analysis. The analysis results indicated that the starting magnetic leucoxene is of rutile phase while the synthesized nanosheets are of titanate structure (H2TixO2x + 1). After calcination at the temperature range of 300 and 400 °C, the calcined samples demonstrated TiO2 (B). At 500 and 600 °C, the calcined nanosheets revealed a bi-crystalline mixture consisting of TiO2 (B) and anatase TiO2. At 700-1000 °C, the crystalline structure shows anatase and rutile phase. At 1100 °C, the prepared samples consisted of a mixture of anatase, rutile phase of TiO2, and Fe2O3 phase. The synthesized product also exhibited the flower-like morphology with 2-5 μm in diameter, and the nanosheets structure was slightly curved, with 100 nm to 2 μm in width and 1-3 nm in thickness. At 100-200 °C showed sheets-like structure. At 300-1100 °C, the calcined nanosheets became unstable and began to decompose and transform into nanoparticles. The increasing size of nanoparticle decreased the specific surface area of the nanosheets, caused by increasing calcination temperature. Furthermore, the BET specific surface area of the nanosheets was approximately 279.8 m2/g. More importantly, the synthesized nanosheets achieved the higher photocatalytic activity under UV and visible light than did the commercial TiO2 nanoparticles (JRC-01, JRC-03, ST-01 and P-25).

Characteristics and phylogenetic analysis of the complete mitochondrial genome of Cheilodactylus quadricornis (Perciformes, Cheilodactylidae).

PubMed

Wang, Aishuai; Sun, Yuena; Wu, Changwen

2016-11-01

The complete mitochondrial genome of the Cheilodactylus quadricornis was firstly determined in the present study. The mitochondrial genome of C. quadricornis is 16 521 nucleotides, comprising 13 protein-coding genes and 2 ribosomal RNA genes, 22 tRNA genes and 2 main non-coding regions (the control region and the origin of the light-strand replication). The overall base composition was T, 26.3%; C, 29.6%; A, 27.8% and G, 16.3%. The gene arrangement, base composition, and tRNA structures of the complete mitochondrial genome of C. quadricornis is similar to other teleosts. Only two central conserved sequence blocks (CSB-2 and CSB-3) were identified in the control region. In addition, the conserved motif 5'-GCCGG-3' was identified in the origin of light-strand replication of C. quadricornis. The complete mitochondrial genome of C. quadricornis was used to construct phylogenetic tree, which shows that C. quadricornis and C. variegatus clustered in a clade and formed a sister relationship. This mitogenome sequence data would play an important role in population genetics and phylogenetic analysis of the Cheilodactylidae.

Dimeric c-di-GMP is required for post-translational regulation of alginate production in Pseudomonas aeruginosa

DOE PAGES

Whitney, John C.; Robinson, Howard; Whitfield, Gregory B.; ...

2015-05-15

Pseudomonas aeruginosa is an opportunistic human pathogen that secretes the exopolysaccharide alginate during infection of the respiratory tract of individuals afflicted with cystic fibrosis and chronic obstructive pulmonary disease. Among the proteins required for alginate production, Alg44 has been identified as an inner membrane protein whose bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) binding activity post-translationally regulates alginate secretion. In this study, we report the 1.8 Å crystal structure of the cytoplasmic region of Alg44 in complex with dimeric self-intercalated c-di-GMP and characterize its dinucleotide-binding site using mutational analysis. The structure shows that the c-di-GMP binding region of Alg44 adopts a PilZmore » domain fold with a dimerization mode not previously observed for this family of proteins. Moreover, calorimetric binding analysis of residues in the c-di-GMP binding site demonstrate that mutation of Arg-17 and Arg-95 alters the binding stoichiometry between c-di-GMP and Alg44 from 2:1 to 1:1. Introduction of these mutant alleles on the P. aeruginosa chromosome show that the residues required for binding of dimeric c-di-GMP in vitro are also required for efficient alginate production in vivo. Our results suggest that the dimeric form of c-di-GMP represents the biologically active signaling molecule needed for the secretion of an important virulence factor produced by P. aeruginosa.« less

Dimeric c-di-GMP is required for post-translational regulation of alginate production in Pseudomonas aeruginosa

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

Whitney, John C.; Robinson, Howard; Whitfield, Gregory B.

Pseudomonas aeruginosa is an opportunistic human pathogen that secretes the exopolysaccharide alginate during infection of the respiratory tract of individuals afflicted with cystic fibrosis and chronic obstructive pulmonary disease. Among the proteins required for alginate production, Alg44 has been identified as an inner membrane protein whose bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) binding activity post-translationally regulates alginate secretion. In this study, we report the 1.8 Å crystal structure of the cytoplasmic region of Alg44 in complex with dimeric self-intercalated c-di-GMP and characterize its dinucleotide-binding site using mutational analysis. The structure shows that the c-di-GMP binding region of Alg44 adopts a PilZmore » domain fold with a dimerization mode not previously observed for this family of proteins. Moreover, calorimetric binding analysis of residues in the c-di-GMP binding site demonstrate that mutation of Arg-17 and Arg-95 alters the binding stoichiometry between c-di-GMP and Alg44 from 2:1 to 1:1. Introduction of these mutant alleles on the P. aeruginosa chromosome show that the residues required for binding of dimeric c-di-GMP in vitro are also required for efficient alginate production in vivo. Our results suggest that the dimeric form of c-di-GMP represents the biologically active signaling molecule needed for the secretion of an important virulence factor produced by P. aeruginosa.« less

Dimeric c-di-GMP Is Required for Post-translational Regulation of Alginate Production in Pseudomonas aeruginosa*

PubMed Central

Whitney, John C.; Whitfield, Gregory B.; Marmont, Lindsey S.; Yip, Patrick; Neculai, A. Mirela; Lobsanov, Yuri D.; Robinson, Howard; Ohman, Dennis E.; Howell, P. Lynne

2015-01-01

Pseudomonas aeruginosa is an opportunistic human pathogen that secretes the exopolysaccharide alginate during infection of the respiratory tract of individuals afflicted with cystic fibrosis and chronic obstructive pulmonary disease. Among the proteins required for alginate production, Alg44 has been identified as an inner membrane protein whose bis-(3′,5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) binding activity post-translationally regulates alginate secretion. In this study, we report the 1.8 Å crystal structure of the cytoplasmic region of Alg44 in complex with dimeric self-intercalated c-di-GMP and characterize its dinucleotide-binding site using mutational analysis. The structure shows that the c-di-GMP binding region of Alg44 adopts a PilZ domain fold with a dimerization mode not previously observed for this family of proteins. Calorimetric binding analysis of residues in the c-di-GMP binding site demonstrate that mutation of Arg-17 and Arg-95 alters the binding stoichiometry between c-di-GMP and Alg44 from 2:1 to 1:1. Introduction of these mutant alleles on the P. aeruginosa chromosome show that the residues required for binding of dimeric c-di-GMP in vitro are also required for efficient alginate production in vivo. These results suggest that the dimeric form of c-di-GMP represents the biologically active signaling molecule needed for the secretion of an important virulence factor produced by P. aeruginosa. PMID:25817996

Oxalato-bridged dinuclear complexes of Cr(III) and Fe(III): synthesis, structure, and magnetism of [(C2H5)4N]4[MM'(ox)(NCS)8] with MM' = CrCr, FeFe, and CrFe.

PubMed

Triki, S; Bérézovsky, F; Sala Pala, J; Coronado, E; Gómez-García, C J; Clemente, J M; Riou, A; Molinié, P

2000-08-21

A new series of homo- and heterometallic oxalato-bridged dinuclear compounds of formulas [Et4N]4[MM'(ox)(NCS)8] ([Et4N]+ = [(C2H5)4N]+; ox = C2O4(2-)) with MM' = Cr(III)-Cr(III) (1), Fe(III)-Fe(III) (2), and Cr(III)-Fe(III) (3) is reported. They have been structurally characterized by infrared spectra and single-crystal X-ray diffraction. The three compounds are isostructural and crystallize in the orthorhombic space group Cmca with Z = 8, a = 16.561(8) A, b = 13.481(7) A, and c = 28.168(8) A for 1, a = 16.515(2) A, b = 13.531(1) A, and c = 28.289(4) A for 2, a = 16.664(7) A, b = 13.575(6) A, and c = 28.386(8) A for 3. The structure of 3 is made up of a discrete dinuclear anion [CrFe(ox)(NCS)8]4- and four disordered [Et4N]+ cations, each of them located on special positions. The anion, in a crystallographically imposed C2h symmetry, contains metal cations in distorted octahedral sites. The Cr(ox)Fe group, which is planar within 0.02 A, presents an intramolecular metal-metal distance of 5.43 A. Magnetic susceptibility measurements indicate antiferromagnetic pairwise interactions for 1 and 2 with J = -3.23 and -3.84 cm-1, respectively, and ferromagnetic Cr-Fe coupling with J = 1.10 cm-1 for 3 (J being the parameter of the exchange Hamiltonian H = -2JS1S2). The ESR spectra at different temperatures confirm the magnetic susceptibility data.

Molecular structure and conformation of N-2-[3'-(methoxysalicylideneimino)benzyl]-3″-methoxysalicylideneimine

NASA Astrophysics Data System (ADS)

Dey, D. K.; Dey, S. P.; Elmali, A.; Elerman, Y.

2001-05-01

The Schiff base, N-2-[3'-(methoxysalicylideneimino)benzyl]-3″-methoxysalicylidene-imine, 1,2-C 6H 4[NCHC 6H 3(OMe-3')OH-2']CH 2NCHC 6H 3(OMe-3″)OH-2″, has been prepared by the reaction of 2-amino-1-benzylamine and 3-methoxysalicylaldehyde ( o-vanillin) in ethanol. The molecular structure has been confirmed by single crystal X-ray crystallography. The crystal is in the monoclinic space group P2 1/ n with a=16.179(5), b=6.715(5), c=18.780(6) Å, β=100.56(3)°, Dcalc=1.293 mg cm -3, V=2006(2) Å 3 and R=0.0357 for 3929 independent reflections. The 1H and 13C NMR spectra in CDCl 3 solution indicate the retention of solid state structure in solution. The title compound is not planar. Intramolecular hydrogen bonds occur between O(1) and N(1) [2.614(2) Å] and between O(2) and N(2) [2.585(2) Å] atoms, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformations from AM1 were calculated as a function of five torsion angles θ1 (C6-C7-N1-C8), θ2 (C14-N2-C15-C16), θ3 (C9-C8-N1-C7), θ4 (C13-C14-N2-C15) and θ5 (C10-C9-C8-N1), varied every 5°. The optimized geometry of the crystal structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by non-bonded hydrogen-hydrogen repulsions.

Thermal-induced structural and optical investigations of Agsbnd ZnO nanocomposite thin films

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.

2018-07-01

In the present paper, we have successfully synthesized Agsbnd ZnO nanocomposite thin films by RF-magnetron sputtering technique at room temperature. Systematic investigations of thermal-induced structural and optical modifications in Agsbnd ZnO thin films have been observed and described. The Agsbnd ZnO thin films were annealed at three different temperatures of 300 °C, 400 °C and 500 °C in vacuum to prevent the oxidation of Ag. The presence and formation of Ag nanoparticles were estimated by transmission electron microscopy. X-ray diffraction analysis revealed the structural information about the crystalline quality of ZnO. The crystallinity as well as the crystallite size of the films have been found to be improved with annealing temperatures. The estimated crystallite size was ∼15.8 nm for as-deposited film and 19.0 nm for the film at a higher temperature. The chemical composition and structural analysis of as-deposited film were carried out by X-ray photoelectron spectroscopy. A very sharp absorption band appeared at ∼540 nm for Ag NPs that is associated with the surface plasmon resonance band of Ag. A noticeable red shift of about ∼12 nm has been recorded for films annealed at 500 °C. Atomic force microscopy has been utilized to examine the surface morphology of the as-deposited and annealed films. The grain size was found to be increase with increasing annealing temperature, while no significant changes were observed in the roughness of Agsbnd ZnO thin films. Raman spectroscopy revealed lattice defects and disordering in the films after the thermal annealing.

Structures of (2E,5E)-2-(4-cyanobenzylidene)-5-(4-dimethylaminobenzylidene)cyclopentanone and (2E,5E)-2-benzylidene-5-cinnamylidenecyclopentanone

NASA Astrophysics Data System (ADS)

Zoto, Christopher A.; MacDonald, John C.

2017-10-01

The X-ray crystal structures of (2E,5E)-2-(4-cyanobenzylidene)-5-(4-dimethylaminobenzylidene)cyclopentanone (I) and (2E,5E)-2-benzylidene-5-cinnamylidenecyclopentanone (II) are presented, compared to the gas phase structures calculated using density functional theory, and discussed in the context of the photophysical behavior exhibited by I and II. Compound I crystallizes in the triclinic space group P 1 bar with a = 6.8743(2) Å, b = 8.8115(2) Å, c = 14.9664(4) Å, α = 77.135(2)°, β = 81.351(2)°, γ = 80.975(2)°, and Z = 2, and exhibits a planar structure. Compound II crystallizes in the monoclinic space group C2/c with a = 33.4281(10) Å, b = 11.9668(4) Å, c = 7.8031(2) Å, β = 92.785(2)°, and Z = 8, and adopts a nonplanar structure in the solid state and calculated structure.

Dipicolinate salt of imidazole: Discovering its structure and properties using different experimental methodologies and quantum chemical investigations

NASA Astrophysics Data System (ADS)

Thirumurugan, R.; Anitha, K.

2018-03-01

A novel organic proton transfer complex of imidazolium dipicolinate (ID) has been synthesized and it was grown as single crystals using slow evaporation method. The molecular structure of synthesized compound and vibrational modes of its functional groups were confirmed by (1H and 13C) NMR, FTIR and FT-Raman spectroscopic studies, respectively. Single crystal X-ray diffraction (SCXRD) analysis confirmed the orthorhombic system with noncentrosymmetric (NCS), P212121, space group of grown ID crystal. UV-Vis-NIR spectral study confirmed its high optical transparency within the region of 285-1500 nm. Powder second harmonic generation (SHG) efficiency of ID crystal was confirmed and it was 6.8 times that of KDP crystal. TG-DTA and DSC analysis revealed the higher thermal stability of grown crystal as 249 °C. The dielectric response and mechanical behaviour of grown crystal were studied effectively. Density functional theory calculations were performed to probe the relationship between the structure and its properties including molecular optimization, Mulliken atomic charge distribution, frontier molecular orbital (FMOs) and molecular electrostatic potential map (MEP) analysis and first hyperpolarizability. All these experimental and computational results were discussed in this communication and it endorsed the ID compound as a potential NLO candidate could be employed in optoelectronics device applications in near future.

A3V5O14 (A = K+, Rb+, or Tl+), new polar oxides with a tetragonal tungsten bronze related structural topology: synthesis, structure, and functional properties.

PubMed

Yeon, Jeongho; Kim, Sang-Hwan; Halasyamani, P Shiv

2010-08-02

Three polar noncentrosymmetric (NCS) oxide materials, A(3)V(5)O(14) (A = K(+), Rb(+), or Tl(+)), have been synthesized by hydrothermal and conventional solid state techniques. Their crystal structures and functional properties (second-harmonic generation, piezoelectricity, and polarization) have been determined. The iso-structural materials exhibit a layered structural topology that consists of corner-sharing VO(4) tetrahedra and VO(5) square pyramids. The layers stack parallel to the c-axis direction and are separated by the K(+), Rb(+), or Tl(+) cations. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate the materials exhibit moderate SHG efficiencies of approximately 100 x alpha-SiO(2). Additional SHG measurements, that is, particle size versus SHG efficiency, indicate the materials are type-I phase-matchable. Converse piezoelectric measurements for K(3)V(5)O(14), Rb(3)V(5)O(14), and Tl(3)V(5)O(14) revealed d(33) values of 28, 22, and 26 pm/V, respectively. Pyroelectric measurements, that is, temperature-dependent polarization measurements, resulted in pyroelectric coefficients of -2.2, -2.9, and -2.8 microC/m(2) x K at 65 degrees C, for K(3)V(5)O(14), Rb(3)V(5)O(14), and Tl(3)V(5)O(14) respectively. Frequency-dependent polarization measurements confirmed that all of the materials are nonferroelectric, consistent with our first principle density functional theory (DFT) electronic structure calculations. Infrared, UV-vis, thermogravimetric, and differential scanning calorimetry measurements were also performed. Crystal data: K(3)V(5)O(14), trigonal, space group P31m (No. 157), a = 8.6970(16) A, c = 4.9434(19) A, V = 323.81(15), and Z = 1; Rb(3)V(5)O(14), trigonal, space group P31m (No. 157), a = 8.7092(5) A, c = 5.2772(7) A, V = 346.65(5), and Z = 1; Tl(3)V(5)O(14), trigonal, space group P31m (No. 157), a = 8.7397(8) A, c = 5.0846(10) A, V = 336.34(8), and Z = 1.

Design of Phosphonium-Type Zwitterion as an Additive to Improve Saturated Water Content of Phase-Separated Ionic Liquid from Aqueous Phase toward Reversible Extraction of Proteins

PubMed Central

Ito, Yoritsugu; Kohno, Yuki; Nakamura, Nobuhumi; Ohno, Hiroyuki

2013-01-01

We designed phosphonium-type zwitterion (ZI) to control the saturated water content of separated ionic liquid (IL) phase in the hydrophobic IL/water biphasic systems. The saturated water content of separated IL phase, 1-butyl-3-methyimidazolium bis(trifluoromethanesulfonyl)imide, was considerably improved from 0.4 wt% to 62.8 wt% by adding N,N,N-tripentyl-4-sulfonyl-1-butanephosphonium-type ZI (P555C4S). In addition, the maximum water content decreased from 62.8 wt% to 34.1 wt% by increasing KH2PO4/K2HPO4 salt content in upper aqueous phosphate buffer phase. Horse heart cytochrome c (cyt.c) was dissolved selectively in IL phase by improving the water content of IL phase, and spectroscopic analysis revealed that the dissolved cyt.c retained its higher ordered structure. Furthermore, cyt. c dissolved in IL phase was re-extracted again from IL phase to aqueous phase by increasing the concentration of inorganic salts of the buffer solution. PMID:24013379

C-Methylated Flavonoid Glycosides from Pentarhizidium orientale Rhizomes and Their Inhibitory Effects on the H1N1 Influenza Virus.

PubMed

Huh, Jungmoo; Ha, Thi Kim Quy; Kang, Kyo Bin; Kim, Ki Hyun; Oh, Won Keun; Kim, Jinwoong; Sung, Sang Hyun

2017-10-27

Thirteen C-methylated flavonoid glycosides (1-13), along with 15 previously known flavonoids (14-28), were isolated from rhizomes of Pentarhizidium orientale. Among these compounds, matteuorienates D-K (1-8) were obtained as analogues of matteuorienates A-C (14-16), which contain a characteristic 3-hydroxy-3-methylglutaryl (HMG) moiety. The structures of 1-13 were characterized by spectroscopic analysis and chemical derivatization. The isolates were evaluated for their antiviral activities against influenza virus (H1N1), with compounds 21, 22, 23, 25, and 26 showing inhibitory effects (IC 50 of 23.9-30.3 μM) against neuraminidases.

Synthesis and Electrochemical Properties of LiFePO4/C for Lithium Ion Batteries.

PubMed

Gao, Hong; Wang, Jiazhao; Yin, Shengyu; Zheng, Hao; Wang, Shengfu; Feng, Chuanqi; Wang, Shiquan

2015-03-01

LiFePO4/C was prepared through a facile rheological phase reaction method by using Fe3(PO4)2, Li3PO4 · 8H2O, and glucose as reactants. The LiFePO4/C samples were characterized by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The electrochemical properties of the samples were investigated. The results show that the LiFePO4/C samples have single-phase olivine-type structure, and their particles feature a spherical shape. The carbon coating on the particles of LiFePO4 is about 1.8% of the LiFePO4/C by weight. The particle size was distributed from 0.2 to 1 µm. The initial discharge capacity of LiFePO4/C reached 154 mA h/g at 0.1 C. The retained discharge capacity of LiFePO4/C was 152.9 mA h g(-1) after 50 cycles. The LiFePO4/C also showed better cycling performance than that of the bare LiPeO4 at a higher charge/discharge rate (1 C). The LIFePO4/C prepared in this way could be a promising cathode material for lithium ion battery application.

Solution structure of murine macrophage inflammatory protein-2.

PubMed

Shao, W; Jerva, L F; West, J; Lolis, E; Schweitzer, B I

1998-06-09

The solution structure of murine macrophage inflammatory protein-2 (MIP-2), a heparin-binding chemokine that is secreted in response to inflammatory stimuli, has been determined using two-dimensional homonuclear and heteronuclear NMR spectroscopy. Structure calculations were carried out by means of torsion-angle molecular dynamics using the program X-PLOR. The structure is based on a total of 2390 experimental restraints, comprising 2246 NOE-derived distance restraints, 44 distance restraints for 22 hydrogen bonds, and 100 torsion angle restraints. The structure is well-defined, with the backbone (N, Calpha, C) and heavy atom atomic rms distribution about the mean coordinates for residues 9-69 of the dimer being 0.57 +/- 0.16 A and 0.96 +/- 0.12 A, respectively. The N- and C-terminal residues (1-8 and 70-73, respectively) are disordered. The overall structure of the MIP-2 dimer is similar to that reported previously for the NMR structures of MGSA and IL-8 and consists of a six-stranded antiparallel beta-sheet (residue 25-29, 39-44, and 48-52) packed against two C-terminal antiparallel alpha-helices. A best fit superposition of the NMR structure of MIP-2 on the structures of MGSA, NAP-2, and the NMR and X-ray structures of IL-8 are 1.11, 1.02, 1.27, and 1.19 A, respectively, for the monomers, and 1.28, 1.10, 1.55, and 1.36 A, respectively, for the dimers (IL-8 residues 7-14 and 16-67, NAP-2 residues 25-84). At the tertiary level, the main differences between the MIP-2 solution structure and the IL-8, MGSA, and NAP-2 structures involve the N-terminal loop between residues 9-23 and the loops formed by residues 30-38 and residues 53-58. At the quaternary level, the difference between MIP-2 and IL-8, MGSA, or NAP-2 results from differing interhelical angles and separations.

Structural composition of organic matter in particle-size fractions of soils along a climo-biosequence in the main range of Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Jafarzadeh-Haghighi, Amir Hossein; Shamshuddin, Jusop; Hamdan, Jol; Zainuddin, Norhazlin

2016-09-01

Information on structural composition of organic matter (OM) in particle-size fractions of soils along a climo-biosequence is sparse. The objective of this study was to examine structural composition and morphological characteristics of OM in particle-size fractions of soils along a climo-biosequence in order to better understand the factors and processes affecting structural composition of soil organic matter. To explore changes in structural composition of OM in soils with different pedogenesis, the A-horizon was considered for further analyses including particle-size fractionation, solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Due to the increase in the thickness of organic layer with increasing elevation, the A-horizon was situated at greater depth in soils of higher elevation. The relationship between relative abundances of carbon (C) structures and particle-size fractions was examined using principal component analysis (PCA). It was found that alkyl C (20.1-73.4%) and O-alkyl C (16.8-67.7%) dominated particle-size fractions. The proportion of alkyl C increased with increasing elevation, while O-alkyl C showed an opposite trend. Results of PCA confirmed this finding and showed the relative enrichment of alkyl C in soils of higher elevation. Increase in the proportion of alkyl C in 250-2000 μm fraction is linked to selective preservation of aliphatic compounds derived from root litter. SEM results showed an increase in root contribution to the 250-2000 μm fraction with increasing elevation. For the <53 μm fraction, pedogenic process of podzolization is responsible for the relative enrichment of alkyl C. This study demonstrates that changes in structural composition of OM in particle-size fractions of soils along the studied climo-biosequence are attributed to site-specific differences in pedogenesis as a function of climate and vegetation.

Precise side-chain conformation analysis of L-phenylalanine in α-helical polypeptide by quantum-chemical calculation and 13C CP-MAS NMR measurement

NASA Astrophysics Data System (ADS)

Niimura, Subaru; Suzuki, Junya; Kurosu, Hiromichi; Yamanobe, Takeshi; Shoji, Akira

2010-04-01

To clarify the positive role of side-chain conformation in the stability of protein secondary structure (main-chain conformation), we successfully calculated the optimization structure of a well-defined α-helical octadecapeptide composed of L-alanine (Ala) and L-phenylalanine (Phe) residues, H-(Ala) 8-Phe-(Ala) 9-OH, based on the molecular orbital calculation with density functional theory (DFT/B3LYP/6-31G(d)). From the total energy and the precise secondary structural parameters such as main-chain dihedral angles and hydrogen-bond parameters of the optimized structure, we confirmed that the conformational stability of an α-helix is affected dominantly by the side-chain conformation ( χ1) of the Phe residue in this system: model A ( T form: around 180° of χ1) is most stable in α-helix and model B ( G + form: around -60° of χ1) is next stable, but model C ( G - form: around 60° of χ1) is less stable. In addition, we demonstrate that the stable conformation of poly( L-phenylalanine) is an α-helix with the side-chain T form, by comparison of the carbonyl 13C chemical shift measured by 13C CP-MAS NMR and the calculated one.

Structure, mechanical, and frictional properties of hydrogenated fullerene-like amorphous carbon film prepared by direct current plasma enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Wang, Yongfu; Gao, Kaixiong; Zhang, Junyan

2016-07-01

In this study, fullerene like carbon (FL-C) is introduced in hydrogenated amorphous carbon (a-C:H) film by employing a direct current plasma enhanced chemical vapor deposition. The film has a low friction and wear, such as 0.011 and 2.3 × 10-9mm3/N m in the N2, and 0.014 and 8.4 × 10-8mm3/N m in the humid air, and high hardness and elasticity (25.8 GPa and 83.1%), to make further engineering applications in practice. It has several nanometers ordered domains consisting of less frequently cross-linked graphitic sheet stacks. We provide new evidences for understanding the reported Raman fit model involving four vibrational frequencies from five, six, and seven C-atom rings of FL-C structures, and discuss the structure evolution before or after friction according to the change in the 1200 cm-1 Raman band intensity caused by five- and seven-carbon rings. Friction inevitably facilitates the transformation of carbon into FL-C nanostructures, namely, the ultra low friction comes from both such structures within the carbon film and the sliding induced at friction interface.

The Crystal Structure of PF-8, the DNA Polymerase Accessory Subunit from Kaposi's Sarcoma-Associated Herpesvirus

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

Baltz, Jennifer L.; Filman, David J.; Ciustea, Mihai

2009-12-01

Kaposi's sarcoma-associated herpesvirus is an emerging pathogen whose mechanism of replication is poorly understood. PF-8, the presumed processivity factor of Kaposi's sarcoma-associated herpesvirus DNA polymerase, acts in combination with the catalytic subunit, Pol-8, to synthesize viral DNA. We have solved the crystal structure of residues 1 to 304 of PF-8 at a resolution of 2.8 {angstrom}. This structure reveals that each monomer of PF-8 shares a fold common to processivity factors. Like human cytomegalovirus UL44, PF-8 forms a head-to-head dimer in the form of a C clamp, with its concave face containing a number of basic residues that are predictedmore » to be important for DNA binding. However, there are several differences with related proteins, especially in loops that extend from each monomer into the center of the C clamp and in the loops that connect the two subdomains of each protein, which may be important for determining PF-8's mode of binding to DNA and to Pol-8. Using the crystal structures of PF-8, the herpes simplex virus catalytic subunit, and RB69 bacteriophage DNA polymerase in complex with DNA and initial experiments testing the effects of inhibition of PF-8-stimulated DNA synthesis by peptides derived from Pol-8, we suggest a model for how PF-8 might form a ternary complex with Pol-8 and DNA. The structure and the model suggest interesting similarities and differences in how PF-8 functions relative to structurally similar proteins.« less

Nouvelle serie d'oxydes derives de la structure de α-U 3U 8: MIIUMo 4O 16

NASA Astrophysics Data System (ADS)

Lee, M. R.; Jaulmes, S.

1987-04-01

A new family of isotypical oxides MIIUMo 4O 16 ( MII = Mg,Mn,Cd,Ca,Hg,Sr,Pb) is identified. The structure of the compound with Ca was determined by X-ray diffraction. It is triclinic, space group P overline1 with a = 13.239(5) Å, b = 6.651(2) Å, c = 8.236(3) Å, α = 90°00(4), β = 90°38(4), γ = 120°16(3), Z = 2. The final index and the weighted Rw index are 0.049 and 0.040, respectively. The cell is related to the orthorhombic one of α-U 3O 8: a = 2 a0, b = -( a0 + b0)/2, c = 2 c0. The structure, reminiscent of that of α-U 3O 8, consists of chains of [Ca,U]O 7 pentagonal bipyramids and MoO 6 octahedra, running parallel to the c axis. The UO distances along the UOCaO chains are shortened to 1.77(1) Å. The uranyl ion was characterized by its IR spectrum.

Enhancing the cellular anti-proliferation activity of pyridazinones as c-met inhibitors using docking analysis.

PubMed

Xing, Weiqiang; Ai, Jing; Jin, Shiyu; Shi, Zhangxing; Peng, Xia; Wang, Lang; Ji, Yinchun; Lu, Dong; Liu, Yang; Geng, Meiyu; Hu, Youhong

2015-05-05

A series of 2, 6-disubstituted pyridazinone derivatives were evaluated and optimized for their c-Met inhibitory activity in enzyme and cellular assay. An analysis of the SAR results arising from computer modeling analysis of members of the library led to the proposal that in order to obtain optimal inhibitory activity in cellular systems the lipophilic/hydrophilic properties of individual structural fragments in the inhibitors need to match those of corresponding binding pockets in the enzyme. Guided by this proposal, the quinoline-pyridazinone 8a, containing hydrophobic 6-indolyl pyridazinone and quinoline moieties along with a hydrophilic morpholine terminal group, was designed and synthesized. The results of studies with this substance showed that it is a selective c-Met inhibitor with both a high enzyme inhibition IC50 value of 4.2 nM and a high EBC-1 cell proliferation inhibition IC50 value of 17 nM. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Determination of molecular structure of succinic acid in a very complex conformational landscape: Gas-phase electron diffraction (GED) and ab initio studies

NASA Astrophysics Data System (ADS)

Vogt, Natalja; Abaev, Maxim A.; Rykov, Anatolii N.; Shishkov, Igor F.

2011-06-01

The molecular structure of succinic acid has been investigated by the gas-phase electron diffraction (GED) method for the first time. According to predictions of MP2/cc-pVTZ calculations, the molecule has 18 stable conformers with the C sbnd C sbnd C sbnd C chain in the gauche ( G) or anti ( A) configuration, and four of them, I ( G), II ( A), III ( G) and IV ( A) belonging to the C 2, C 2h, C 1 and C 1 point groups, respectively, with relative energies ΔE ZPE within 2.2 kcal/mol can be present at the experimental temperature of 445 K in noticeable amounts. The ratio of the conformers I:II:III:IV = 45(15):20(15):10(assumed):25(15) (in %) has been determined in the GED analysis guided by theoretical predictions. To take into account vibrational effects, the corrections Δ( r e - r a) to the experimental r a bond lengths were calculated from the MP2/cc-pVTZ quadratic and cubic force constants. The obtained equilibrium structural parameters of the dominant conformer I are the following (bond lengths in Å, angles in degrees): r e(C sp3sbnd C sp3) = 1.508(3), r e(C sp3sbnd C sp2) = 1.499(2), r e(C sbnd O) = 1.343(2), r e(C dbnd O) = 1.202(1), e(C sbnd C sbnd C) = 111.8(4), e(C sbnd C sbnd O) = 112.0(4), e(O sbnd C dbnd O) = 123.0(1), τ(C sbnd C sbnd C sbnd C) = 69.9(11). Yielding the best agreement with the GED structure, the MP2/cc-pVQZ approximation overestimates the C sbnd O and C dbnd O bond lengths by ca. 0.005(2) Å.

Noncanoncial signal recognition particle RNAs in a major eukaryotic phylum revealed by purification of SRP from the human pathogen Cryptococcus neoformans

PubMed Central

Dumesic, Phillip A.; Rosenblad, Magnus A.; Samuelsson, Tore; Nguyen, Tiffany; Moresco, James J.; Yates, John R.; Madhani, Hiten D.

2015-01-01

Despite conservation of the signal recognition particle (SRP) from bacteria to man, computational approaches have failed to identify SRP components from genomes of many lower eukaryotes, raising the possibility that they have been lost or altered in those lineages. We report purification and analysis of SRP in the human pathogen Cryptococcus neoformans, providing the first description of SRP in basidiomycetous yeast. The C. neoformans SRP RNA displays a predicted structure in which the universally conserved helix 8 contains an unprecedented stem-loop insertion. Guided by this sequence, we computationally identified 152 SRP RNAs throughout the phylum Basidiomycota. This analysis revealed additional helix 8 alterations including single and double stem-loop insertions as well as loop diminutions affecting RNA structural elements that are otherwise conserved from bacteria to man. Strikingly, these SRP RNA features in Basidiomycota are accompanied by phylum-specific alterations in the RNA-binding domain of Srp54, the SRP protein subunit that directly interacts with helix 8. Our findings reveal unexpected fungal SRP diversity and suggest coevolution of the two most conserved SRP features—SRP RNA helix 8 and Srp54—in basidiomycetes. Because members of this phylum include important human and plant pathogens, these noncanonical features provide new targets for antifungal compound development. PMID:26275773

Crystal structures of two bis-(iodo-meth-yl)benzene derivatives: similarities and differences in the crystal packing.

PubMed

McAdam, C John; Hanton, Lyall R; Moratti, Stephen C; Simpson, Jim

2015-12-01

The isomeric derivatives 1,2-bis-(iodo-meth-yl)benzene, (I), and 1,3-bis-(iodo-meth-yl)benzene (II), both C8H8I2, were prepared by metathesis from their di-bromo analogues. The ortho-derivative, (I), lies about a crystallographic twofold axis that bis-ects the C-C bond between the two iodo-methyl substituents. The packing in (I) relies solely on C-H⋯I hydrogen bonds supported by weak parallel slipped π-π stacking inter-actions [inter-centroid distance = 4.0569 (11) Å, inter-planar distance = 3.3789 (8) Å and slippage = 2.245 Å]. While C-H⋯I hydrogen bonds are also found in the packing of (II), type II, I⋯I halogen bonds [I⋯I = 3.8662 (2) Å] and C-H⋯π contacts feature prominently in stabilizing the three-dimensional structure.

Structure cristalline de NaLiYb/sub 2/F/sub 8/: composes isotypes

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

Dib, A.; Gorius, M.F.; Aleonard, S.

1986-11-15

NaLiYb/sub 2/F/sub 8/ crystallizes in the monoclinic system, space group C2/c, with a = 10.3516(9), b = 8.2069(9), c = 6,9674(7) A, ..beta.. = 90/sup 0/, Z = 4. The crystal structure has been solved from single crystal diffractometer measurements (AgK..cap alpha.. radiation) using Patterson and Fourier syntheses and refined by a least-squares method. The final R value is 0.021 for 1756 independent observed reflections. Two YbF/sub 8/ polyhedra share one of their edges to form Yb/sub 2/F/sub 14/ groups which are three-dimensionally linked and create cavities in which Na and Li are located. Yb/sub 2/F/sub 14/ groups share twomore » of their edges with these of one NaF/sub 7/ (or NaF/sub 9/ polyhedron to form Y/sub 2/NaF/sub 20/ blocks. As well, the structure may be described by the packing of planes formed by these two-dimensionally linked blocks. The description of this structure is compared with that ascribed to NaLiY/sub 2/F/sub 8/, which has been described in the monoclinic system, space group P2/sub 1//m, with a' = (a + b)/2, b' = c,c' = (b - a)/2, Z = 2. It is shown that positions of the atoms confer pseudoorthorhombic symmetry on the cell. Lattice parameters of isotypic compounds are given in the pseudoorthorhombic lattice and they are compared with those recently published with the structure described in the monoclinic system, space group P2/sub 1//m.« less

Crystal structures of 2,3,8,9,14,15-hexa-methyl-5,6,11,12,17,18-hexa-aza-tri-naphthyl-ene and 2,3,8,9,14,15-hexa-phenyl-5,6,11,12,17,18-hexa-za-tri-naphthyl-ene di-chloro-methane disolvate.

PubMed

Fangmann, Pia; Schmidtmann, Marc; Beckhaus, Rüdiger

2018-02-01

The crystal structures of two substituted HATN (hexa-aza-tri-naphthyl-ene) derivatives, namely 2,3,8,9,14,15-hexa-methyl- and 2,3,8,9,14,15-hexa-phenyl-5,6,11,12,17,18- hexa-zatri-naphthyl-ene (HATNMe 6 and HATNPh 6 ), are reported. Whereas the structure of the methyl-substituted derivative (HATNMe 6 ) contains no solvent mol-ecules (C 30 H 24 N 6 ), the hexa-phenyl-substituted structure (HATNPh 6 ) contains two mol-ecules of di-chloro-methane (C 60 H 36 N 6 ·2CH 2 Cl 2 ). This class of planar bridging ligands is known for its electron-deficient systems and its ability to form π-π stacking inter-actions. Indeed, in both crystal structures strong π-π stacking inter-actions are observed, but with different packing features. The di-chloro-methane mol-ecules in the crystal structure of HATNPh 6 are situated in the voids and are involved in C-H⋯N contacts to the nitro-gen atoms of the pyrazine units.

Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-two-dimensional honeycomb lattice compound N a2C o2Te O6

NASA Astrophysics Data System (ADS)

Bera, A. K.; Yusuf, S. M.; Kumar, Amit; Ritter, C.

2017-03-01

The crystal structure, magnetic ground state, and the temperature-dependent microscopic spin-spin correlations of the frustrated honeycomb lattice antiferromagnet N a2C o2Te O6 have been investigated by powder neutron diffraction. A long-range antiferromagnetic (AFM) ordering has been found below TN˜24.8 K . The magnetic ground state, determined to be zigzag antiferromagnetic and characterized by a propagation vector k =(1 /2 0 0 ) , occurs due to the competing exchange interactions up to third-nearest neighbors within the honeycomb lattice. The exceptional existence of a limited magnetic correlation length along the c axis (perpendicular to the honeycomb layers in the a b planes) has been found even at 1.8 K, well below the TN˜24.8 K . The observed limited correlation along the c axis is explained by the disorder distribution of the Na ions within the intermediate layers between honeycomb planes. The reduced ordered moments mCo (1 )=2.77 (3 ) μB/C o2 + and mCo (2 )=2.45 (2 ) μB/C o2 + at 1.8 K reflect the persistence of spin fluctuations in the ordered state. Above TN˜24.8 K , the presence of short-range magnetic correlations, manifested by broad diffuse magnetic peaks in the diffraction patterns, has been found. Reverse Monte Carlo analysis of the experimental diffuse magnetic scattering data reveals that the spin correlations are mainly confined within the two-dimensional honeycomb layers (a b plane) with a correlation length of ˜12 Å at 25 K. The nature of the spin arrangements is found to be similar in both the short-range and long-range ordered magnetic states. This implies that the short-range correlation grows with decreasing temperature and leads to the zigzag AFM ordering at T ≤TN . The present study provides a comprehensive picture of the magnetic correlations over the temperature range above and below the TN and their relation to the crystal structure. The role of intermediate soft Na layers on the magnetic coupling between honeycomb planes is discussed.

On the formation and structure of rare-earth element complexes in aqueous solutions under hydrothermal conditions with new data on gadolinium aqua and chloro complexes

USGS Publications Warehouse

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2007-01-01

Synchrotron X-ray spectroscopy experiments were made on the Gd(III) aqua and chloro complexes in low pH aqueous solutions at temperatures ranging from 25 to 500????C and at pressures up to 480??MPa using a hydrothermal diamond anvil cell. Analysis of fluorescence Gd L3-edge X-ray absorption fine structure (XAFS) spectra measured from a 0.006m Gd/0.16m HNO3 aqueous solution at temperatures up to 500????C and at pressures up to 260??MPa shows that the Gd-O distance of the Gd3+ aqua ion decreases steadily at a rate of ??? 0.007??A??/100????C whereas the number of coordinated H2O molecules decreases from 9.0 ?? 0.5 to 7.0 ?? 0.4. The loss of water molecules in the Gd3+ aqua ion inner hydration shell over this temperature range (a 22% reduction) is smaller than exhibited by the Yb3+ aqua ion (42% reduction) indicating that the former is significantly more stable than the later. We conjecture that the anomalous enrichment of Gd reported from measurement of REE concentrations in ocean waters may be attributed to the enhanced stability of the Gd3+ aqua ion relative to other REEs. Gd L3-edge XAFS measurements of 0.006m and 0.1m GdCl3 aqueous solutions at temperatures up to 500????C and pressures up to 480??MPa reveal that the onset of significant Gd3+-Cl- association occurs around 300????C. Partially-hydrated stepwise inner-sphere complexes most likely of the type Gd(H2O)??-nCln+3-n occur in the chloride solutions at higher temperatures, where ?? ??? 8 at 300????C decreasing slightly to an intermediate value between 7 and 8 upon approaching 500????C. This is the first direct evidence for the occurrence of partially-hydrated REE Gd (this study) and Yb [Mayanovic, R.A., Jayanetti, S., Anderson, A.J., Bassett, W.A., Chou, I-M., 2002a. The structure of Yb3+ aquo ion and chloro complexes in aqueous solutions at up to 500 ??C and 270 MPa. J. Phys. Chem. A 106, 6591-6599.] chloro complexes in hydrothermal solutions. The number of chlorides (n) of the partially-hydrated Gd(III) chloro complexes increases steadily with temperature from 0.4 ?? 0.2 to 1.7 ?? 0.3 in the 0.006m chloride solution and from 0.9 ?? 0.7 to 1.8 ?? 0.7 in the 0.1m GdCl3 aqueous solution in the 300-500????C range. Conversely, the number of H2O ligands of Gd(H2O)??-nCln+3-n complexes decreases steadily from 8.9 ?? 0.4 to 5.8 ?? 0.7 in the 0.006m GdCl3 aqueous solution and from 9.0 ?? 0.5 to 5.3 ?? 1.0 in the 0.1m GdCl3 aqueous solution at temperatures from 25 to 500????C. Analysis of our results shows that the chloride ions partially displace the inner-shell water molecules during Gd(III) complex formation under hydrothermal conditions. The Gd-OH2 bond of the partially-hydrated Gd(III) chloro complexes exhibits slightly smaller rates of length contraction (??? 0.005??A??/100????C) for both solutions. The structural aspects of chloride speciation of Gd(III) as measured from this study and of Yb(III) as measured from our previous experiments are consistent with the solubility of these and other REE in deep-sea hydrothermal fluids. ?? 2006 Elsevier B.V. All rights reserved.

Ultralight anisotropic foams from layered aligned carbon nanotube sheets.

PubMed

Faraji, Shaghayegh; Stano, Kelly L; Yildiz, Ozkan; Li, Ang; Zhu, Yuntian; Bradford, Philip D

2015-10-28

In this work, we present large scale, ultralight aligned carbon nanotube (CNT) structures which have densities an order of magnitude lower than CNT arrays, have tunable properties and exhibit resiliency after compression. By stacking aligned sheets of carbon nanotubes and then infiltrating with a pyrolytic carbon (PyC), resilient foam-like materials were produced that exhibited complete recovery from 90% compressive strain. With density as low as 3.8 mg cm(-3), the foam structure is over 500 times less dense than bulk graphite. Microscopy revealed that PyC coated the junctions among CNTs, and also increased CNT surface roughness. These changes in the morphology explain the transition from inelastic behavior to foam-like recovery of the layered CNT sheet structure. Mechanical and thermal properties of the foams were tuned for different applications through variation of PyC deposition duration while dynamic mechanical analysis showed no change in mechanical properties over a large temperature range. Observation of a large and linear electrical resistance change during compression of the aligned CNT/carbon (ACNT/C) foams makes strain/pressure sensors a relevant application. The foams have high oil absorption capacities, up to 275 times their own weight, which suggests they may be useful in water treatment and oil spill cleanup. Finally, the ACNT/C foam's high porosity, surface area and stability allow for demonstration of the foams as catalyst support structures.

Purification, crystallization and preliminary X-ray analysis of Escherichia coli UDP-N-acetylmuramoyl:L-alanine ligase (MurC).

PubMed

Deva, Taru; Pryor, KellyAnn D; Leiting, Barbara; Baker, Edward N; Smith, Clyde A

2003-08-01

UDP-N-acetylmuramoyl:L-alanine ligase (MurC) is involved in the pathway leading from UDP-N-glucosamine to the UDP-N-acetylmuramoyl:pentapeptide unit, which is the building block for the peptidoglycan layer found in all bacterial cell walls. The pathways leading to the biosynthesis of the peptidoglycan layer are important targets for the development of novel antibiotics, since animal cells do not contain these pathways. MurC is the first of four similar ATP-dependent amide-bond ligases which share primary and tertiary structural similarities. The crystal structures of three of these have been determined by X-ray crystallography, giving insights into the binding of the carbohydrate substrate and the ATP. Diffraction-quality crystals of the enzyme MurC have been obtained in both native and selenomethionine forms and X-ray diffraction data have been collected at the Se edge at a synchrotron source. The crystals are orthorhombic, with unit-cell parameters a = 73.9, b = 93.6, c = 176.8 A, and diffraction has been observed to 2.6 A resolution.

CVD of silicon carbide on structural fibers - Microstructure and composition

NASA Technical Reports Server (NTRS)

Veitch, Lisa C.; Terepka, Francis M.; Gokoglu, Suleyman A.

1992-01-01

Structural fibers are currently being considered as reinforcements for intermetallic and ceramic materials. Some of these fibers, however, are easily degraded in a high temperature oxidative environment. Therefore, coatings are needed to protect the fibers from environmental attack. Silicon carbide (SiC) was chemically vapor deposited (CVD) on Textron's SCS6 fibers. Fiber temperatures ranging from 1350 to 1500 C were studied. Silane (SiH4) and propane (C2H8) were used for the source gases and different concentrations of these source gases were studied. Deposition rates were determined for each group of fibers at different temperatures. Less variation in deposition rates were observed for the dilute source gas experiments than the concentrated source gas experiments. A careful analysis was performed on the stoichiometry of the CVD SiC coating using electron microprobe. Microstructures for the different conditions were compared. At 1350 C, the microstructures were similar; however, at higher temperatures, the microstructure for the more concentrated source gas group were porous and columnar in comparison to the cross sections taken from the same area for the dilute source gas group.

CVD of silicon carbide on structural fibers: Microstructure and composition

NASA Technical Reports Server (NTRS)

Veitch, Lisa C.; Terepka, Francis M.; Gokoglu, Suleyman A.

1992-01-01

Structural fibers are currently being considered as reinforcements for intermetallic and ceramic materials. Some of these fibers, however, are easily degraded in a high temperature oxidative environment. Therefore, coatings are needed to protect the fibers from environmental attack. Silicon carbide (SiC) was chemically vapor deposited (CVD) on Textron's SCS6 fibers. Fiber temperatures ranging from 1350 to 1500 C were studied. Silane (SiH4) and propane (C2H8) were used for the source gases and different concentrations of these source gases were studied. Deposition rates were determined for each group of fibers at different temperatures. Less variation in deposition rates were observed for the dilute source gas experiments than the concentrated source gas experiments. A careful analysis was performed on the stoichiometry of the CVD SiC coating using electron microprobe. Microstructures for the different conditions were compared. At 1350 C, the microstructures were similar; however, at higher temperatures, the microstructure for the more concentrated source gas group were porous and columnar in comparison to the cross sections taken from the same area for the dilute source gas group.

Characteristics of thermostable amylopullulanase of Geobacillus thermoleovorans and its truncated variants.

PubMed

Nisha, M; Satyanarayana, T

2015-05-01

The far-UV CD spectroscopic analysis of the secondary structure in the temperature range between 30 and 90°C revealed a compact and thermally stable structure of C-terminal truncated amylopullulanase of Geobacillus thermoleovorans NP33 (gt-apuΔC) with a higher melting temperature [58°C] than G. thermoleovorans NP33 amylopullulanase (gt-apu) [50°C] and the N-terminal truncated amylopullulanase from G. thermoleovorans NP33 (gt-apuΔN) [55°C]. A significant decline in random coils in gt-apuΔC and gt-apuΔN suggested an improvement in conformational stability, and thus, an enhancement in their thermal stability. The improvement in the thermostability of gt-apuΔC was corroborated by the thermodynamic parameters for enzyme inactivation. The Trp fluorescence emission (335 nm) and the acrylamide quenching constant (22.69 M(-1)) of gt-apuΔC indicated that the C-terminal truncation increases the conformational stability of the protein with the deeply buried tryptophan residues. The 8-Anilino Naphthalene Sulfonic acid (ANS) fluorescence experiments indicated the unfolding of gt-apu to expose its hydrophobic surface to a greater extent than the gt-apuΔC and gt-apuΔN. Copyright © 2015 Elsevier B.V. All rights reserved.

Structures and standard molar enthalpies of formation of a series of Ln(III)–Cu(II) heteronuclear compounds with pyrazine-2,3-dicarboxylic acid

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

Yang, Qi; Xie, Gang; Wei, Qing

2014-07-01

Fifteen lanthanide–copper heteronuclear compounds, formulated as [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 6}]·xH{sub 2}O (1–6(x=2), 8(x=3), 9–10(x=4)); [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 4}]·xH{sub 2}O (7, 12–13, 15(x=4), 14(x=5), 11(x=8)) (Ln(III)=La(1); Ce(2); Pr(3); Nd(4); Sm(5); Eu(6); Gd(7); Tb(8); Dy(9); Ho(10); Er(11); Tm(12); Yb(13); Lu(14); Y(15); H{sub 2}pzdc (C{sub 6}H{sub 4}N{sub 2}O{sub 4})=pyrazine-2,3-dicarboxylic acid) have been hydrothermally synthesized. All compounds were characterized by element analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analyses confirm that all compounds are isostructural and feature a 3D brick-like framework structure with (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 2}.8{sup 2})(6{sup 3}){sup 2}(6{sup 5}.8){sub 2} topology. Using 1 mol cm{supmore » −3} HCl(aq) as calorimetric solvent, with an isoperibol solution–reaction calorimeter, the standard molar enthalpies of formation of all compounds were determined by a designed thermochemical cycle. In addition, solid state luminescence properties of compounds 5, 6, 8 and 9 were studied in the solid state. - Graphical abstract: According to Hess' rule, the standard molar enthalpies of formation of Ln–Cu heterometallic coordination compounds were determined by a designed thermochemical cycle. - Highlights: • Fifteen lanthanide–copper heteronuclear isostructural compounds. • Structurally characterization by IR, X-ray diffraction and thermal analysis. • The standard molar enthalpy of formation. • Isoperibol solution–reaction calorimetry.« less

The Effects of One Amino Acid Substitutions at the C-Terminal Region of Thermostable L2 Lipase by Computational and Experimental Approach.

PubMed

Sani, Hartini Ahmad; Shariff, Fairolniza Mohd; Rahman, Raja Noor Zaliha Raja Abd; Leow, Thean Chor; Salleh, Abu Bakar

2018-01-01

The substitutions of the amino acid at the predetermined critical point at the C-terminal of L2 lipase may increase its thermostability and enzymatic activity, or even otherwise speed up the unfolding of the protein structure. The C-terminal of most proteins is often flexible and disordered. However, some protein functions are directly related to flexibility and play significant role in enzyme reaction. The critical point for mutation of L2 lipase structure was predicted at the position 385 of the L2 sequence, and the best three mutants were determined based on I-Mutant2.0 software. The best three mutants were S385E, S385I and S385V. The effects of the substitution of the amino acids at the critical point were analysed with molecular dynamics simulation by using Yet Another Scientific Artificial Reality Application software. The predicted mutant L2 lipases were found to have lower root mean square deviation value as compared to L2 lipase. It was indicated that all the three mutants had higher compactness in the structure, consequently enhanced the stability. Root mean square fluctuation analysis showed that the flexibility of L2 lipase was reduced by mutations. Purified S385E lipase had an optimum temperature of 80 °C in Tris-HCl pH 8. The highest enzymatic activity of purified S385E lipase was obtained at 80 °C temperature in Tris-HCl pH 8, while for L2 lipase it was at 70 °C in Glycine-NaOH pH 9. The thermal stability of S385V lipase was enhanced as compared to other protein since that the melting point (T m ) value was at 85.96 °C. S385I lipase was more thermostable compared to recombinant L2 lipase and other mutants at temperature 60 °C within 16 h preincubation.

Synthesis and structural and conformational study of some esters derived from 8-β-hydroxy-3-phenethyl-3- azabicyclico [3.2.11] octan-8-α-carboxylic acid

NASA Astrophysics Data System (ADS)

Diez, M.; Izquierdo, M. L.; Arias, M. S.; Galvez, E.; Matesanz, E.; Martinez-Ripoll, M.

1991-09-01

A series of 8-β-hydroxy-8-α-alkoxycarbonyl- N-phenethyl-3-azabicyclo [3.2.1.]octane derivatives have been synthesized and studied by IR, 1H and 13C NMR spectroscopy, and the crystal structure of ethyl-8-β-hydroxy-3-phenethyl-3-azabicyclo [3.2.1] octan-8-α-carboxylate ( Va) has been determined by X-ray diffraction. In deuterochloroform and deuterobenzene the cyclopentane and piperidine rings of the title compounds show an envelope conformation flattened at C8 and a distorted chair conformation puckered at C8 and flattened at N3, respectively, with the N-substituent in an equatorial position. These results are in close agreement with that found for compound Va in the crystalline state. By comparing the NMR and X-ray parameters of the title compounds with those of the corresponding 8-α-hydroxy-8β-alkoxycarbonyl- N-phenethyl-3- azabicyclo [3.2.1] octane epimers and 3-phenethyl-3-azabicyclo [3.2.1] octan-8-α-(andβ)ol, several stereoelectronic effects have been deduced.

Synthesis and structure-activity relationship of di-(3, 8-diazabicyclo[3.2.1]octane) diquaternary ammonium salts as unique analgesics.

PubMed

Liu, Hong; Cheng, Tie-Ming; Zhang, Hong-Mei; Li, Run-Tao

2003-11-01

Based on the structure characteristics of the lead compounds, 1, 1' octanedioyl-4, 4'-dimethyl-4, 4'-dibenzyl dipiperazinium dibromide (2) and 3, 8-disubstituted-3, 8-diazabicyclo [3.2.1]octanes (DBO), di-(3, 8-diazabicyclo [3.2.1]octane) diquaternary ammonium salts 3 a-c were designed and synthesized through a highly practical procedure. Target compounds 3 a-c and the hydrochloride salts of their precursors 10 a-c were evaluated for their in vivo analgesic and sedative activities. Interestingly, the introduction of an endoethylenic bridge in the piperazine of lead compound 2 causes loss of the analgesic activity and increases the toxicity dramatically. This result shows that the flexible conformation of piperazine in compound 2 is favorable for interaction with the receptor, and the quaternization of compounds 10 a-c is the main reason for the toxicity increase.

A Psychometric Analysis and Standardization of the Behavior Assessment System for Children-2, Self-Report of Personality, Child Version among a Korean Sample

ERIC Educational Resources Information Center

Ahn, Christine M.; Ebesutani, Chad; Kamphaus, Randy

2014-01-01

The psychometric properties of the Korean version of the Behavior Assessment System for Children-2, Self-Report of Personality, Child Form (K-BASC-2 SRP-C) are reported. A total of 1100 Korean children ages 8-11 years participated in the study to establish normative data. The results of this study generally supported the factor structure and…

Enhancing the Dependability of Complex Missions Through Automated Analysis

DTIC Science & Technology

2013-09-01

triangular or self - referential relationships. The Semantic Web Rule Language (SWRL)—a W3C-approved OWL extension—addresses some of these limitations by...SWRL extends OWL with Horn-like rules that can model complex relational structures and self - referential relationships; Prolog extends OWL+SWRL with the...8]. Additionally, multi-agent model checking has been used to verify OWL-S process models [9]. OWL is a powerful knowledge representation formalism

Synthesis and characterization of microporous inorganic membranes for propylene/propane separation

NASA Astrophysics Data System (ADS)

Ma, Xiaoli

Membrane-based gas separation is promising for efficient propylene/propane (C3H6/C3H8) separation with low energy consumption and minimum environment impact. Two microporous inorganic membrane candidates, MFI-type zeolite membrane and carbon molecular sieve membrane (CMS) have demonstrated excellent thermal and chemical stability. Application of these membranes into C3H6/C3H 8 separation has not been well investigated. This dissertation presents fundamental studies on membrane synthesis, characterization and C3H 6/C3H8 separation properties of MFI zeolite membrane and CMS membrane. MFI zeolite membranes were synthesized on α-alumina supports by secondary growth method. Novel positron annihilation spectroscopy (PAS) techniques were used to non-destructively characterize the pore structure of these membranes. PAS reveals a bimodal pore structure consisting of intracrystalline zeolitic micropores of ~0.6 nm in diameter and irregular intercrystalline micropores of 1.4 to 1.8 nm in size for the membranes. The template-free synthesized membrane exhibited a high permeance but a low selectivity in C3H 6/C3H8 mixture separation. CMS membranes were synthesized by coating/pyrolysis method on mesoporous gamma-alumina support. Such supports allow coating of thin, high-quality polymer films and subsequent CMS membranes with no infiltration into support pores. The CMS membranes show strong molecular sieving effect, offering a high C3H 6/C3H8 mixture selectivity of ~30. Reduction in membrane thickness from 500 nm to 300 nm causes an increase in C3H8 permeance and He/N2 selectivity, but a decrease in the permeance of He, N 2 and C3H6 and C3H6/C 3H8 selectivity. This can be explained by the thickness dependent chain mobility of the polymer film resulting in final carbon membrane of reduced pore size with different effects on transport of gas of different sizes, including possible closure of C3H6-accessible micropores. CMS membranes demonstrate excellent C3H6/C 3H8 separation performance over a wide range of feed pressure, composition and operation temperature. No plasticization was observed at a feed pressure up to 100 psi. The permeation and separation is mainly controlled by diffusion instead of adsorption. CMS membrane experienced a decline in permeance, and an increase in selectivity over time under on-stream C 3H6/C3H8 separation. This aging behavior is due to the reduction in effective pore size and porosity caused by oxygen chemisorption and physical aging of the membrane structure.

Electrical and galvanomagnetic properties of biocarbon preforms of white pine wood

NASA Astrophysics Data System (ADS)

Popov, V. V.; Orlova, T. S.; Ramirez-Rico, J.

2009-11-01

The electrical and galvanomagnetic properties of high-porosity biocarbon preforms prepared from white pine wood by pyrolysis at carbonization temperatures T carb = 1000 and 2400°C have been studied. Measurements have been made of the behavior with temperature of the electrical resistivity, as well as of magnetoresistance and the Hall coefficient in the 1.8-300-K temperature interval and magnetic fields of up to 28 kOe. It has been shown that samples of both types (with T carb = 1000 and 2400°C) are characterized by high carrier (hole) concentrations of 6.3 × 1020 and 3.6 × 1020 cm-3, respectively. While these figures approach the metallic concentration, the electrical resistivity of the biocarbon materials studied, unlike that of normal metals, grows with decreasing temperature. Increasing T carb brings about a decrease in electrical resistivity by a factor 1.5-2 within the 1.8-300-K temperature range. The magnetoresistance also follows a qualitatively different pattern at low (1.8-4.2 K) temperatures: it is negative for T carb = 2400°C and positive for T carb = 1000°C. An analysis of experimental data has revealed that the specific features in the conductivity and magnetoresistance of these samples are described by quantum corrections associated inherently with structural characteristics of the biocarbon samples studied, more specifically with the difference between the fractions of the quasi-amorphous and nanocrystalline phases, as well as with the fine structure of the latter phase forming at the two different T carb.

[Cloning and bioinformatic analysis and expression analysis of beta-glucuronidase in Scutellaria baicalensis].

PubMed

Guo, Shuang-shuang; Cheng, Lin; Yang, Li-min; Han, Mei

2015-11-01

The β-Glucuronidase gene (sbGUS) cDNA firstly from Scutellari abaicalensis leaf was cloned by RT-PCR, with GenBank accession number KR364726. The full length cDNA of sbGUS was 1 584 bp with an open reading frame (ORF), encoding an unstable protein with 527 amino acids. The bioinformatic analysis showed that the sbGUS encoding protein had isoelectric point (pI) of 5.55 and a calculated molecular weight about 58.724 8 kDa, with a transmembrane regions and signal peptide, had conserved domains of glycoside hydrolase super family and unintegrated trans-glycosidase catalytic structure. In the secondary structure, the percentage of alpha helix, extended strand, β-extended and random coil were 25.62%, 28.84%, 13.28% and 32.26%, respectively. The homologous analysis indicated the nucleotide sequence 98.93% similarity and the amino acid sequence 98.29% similarity with S. baicalensis (BAA97804.1), in the nine positions were different. The expression level of sGUS was the highest in root based on a real-time PCR analysis, followed by flower and stem, and the lowest was in stem. The results provide a foundation for exploring the molecular function of sbGUS involved in baicalcin biosynthesis based on synthetic biology approach in S. baicalensis plants.

Lanthanide Contraction Effect In Magnetic Thermoelectric Materials Of Rare Earth-doped Bi1.5Pb0.5Ca2Co2O8

NASA Astrophysics Data System (ADS)

Sutjahja, Inge Magdalena; Akbar, Taufik; Nugroho, Agung

2010-12-01

We report in this paper the result of synthesis and crystal structure characterization of magnetic thermoelectric materials of rare-earth-doped Bi1.5Pb0.5Ca2Co2O8, namely Bi1.5Pb0.5Ca1.9RE0.1Co2O8 (RE = La, Pr, Sm, Eu, Gd, Ho). Single phase samples have been prepared by solid state reaction process using precursors of Bi2O3, PbO, CaCO3, RE2O3, and Co3O4. The precursors were pulverized, calcinated, and sintered in air at various temperatures for several hours. Analysis of XRD data shows that Bi1.5Pb0.5Ca1.9RE0.1Co2O8 compound is a layered system consisting of an alternate stack of CoO2 layer and Bi2Sr2O4 block along the c-axis. The misfit structure along b-direction is revealed from the difference of the b-axis length belonging to two sublattices, namely hexagonal CdI2-type CoO2 layer and rock-salt (RS) NaCl-type Bi2Sr2O4 block, while they possess the common a- and c-axis lattice parameters and β angles. The overall crystal structure parameters (a, b, and c) increases with type of doping from La to Ho, namely by decreasing the ionic radii of rare-earth ion. We discuss this phenomenon in terms of the lanthanide contraction, an effect commonly found in the rare-earth compound, results from poor shielding of nuclear charge by 4f electrons. In addition, the values of b-lattice parameters in these rare-earth doped samples are almost the same with those belongs to undoped parent compound (Bi1.5Pb0.5Sr2Co2O8) and its related Y-doped (Bi1.5Pb0.5Ca1.9Y0.1Co2O8) samples, while the c-values reduced significantly in rare-earth doped samples, with opposite trend with those of variation of a-axis length. Morevover, the misfit degree in rare-earth doped compound is higher in compared to parent compound and Y-doped samples. We argue that these structural changes induced by rare-earth doping may provide information for the variation of electronic structure of Co-ions (Co3+ and Co4+), in particular their different spin states of low-spin, intermediate-spin, and high-spin. This, in turn, will affect the thermoelectric properties (Seebeck coefficient) of the system.

Out-of-equilibrium Sm Fe based phases

NASA Astrophysics Data System (ADS)

Djéga-Mariadassou, C.; Bessais, L.

2008-02-01

Structure and magnetic properties of nanocrystalline P6/mmm out-of-equilibrium precursors of hard magnetic R-3m Sm2(Fe,M)17C (M=Ga,Si,) and I4/mmm Sm(Fe,Co,Ti)11 equilibrium phases, are presented. Their structure is explained with a model ground on the R1 - s T5 + 2 s formula (R=rare-earth, s=vacancy rate, T=transition metal) where s Sm atoms are statistically substituted by s transition metal pairs. The Rietveld analysis (RA) provides the stoichiometry of the precursors, 1:9 and 1:10, respectively precursor of 2:17 and 1:12 phases. The interpretation of the Mössbauer spectra of the 1:9 and 1:10 phases, is based on the correlation between δ and the Wigner Seitz Cell volumes, calculated from the structural parameters. The δ behaviour of each crystallographic site versus Co content, defines the Co location while it confirms that of Si and Ga obtained by RA. Substitution occurs in 3 g site, whatever Co or M. The Sm(Fe,Co,Ti)10 and Sm(Fe,M)9C Curie temperature (Tc) are compared to those of the equilibrium phases, the effects of Fe substitution and C addition are discussed. The maximum μ 0Hc is obtained for low M or Co content, for auto-coherent diffraction domain size ˜30 nm. SmFe8.75Ga0.25C and SmFe8.75Si0.25C with Tc of 680 and 690 K, show respectively Mr and μ 0Hc of 58 emu/g, 27 kOe and 95 emu/g, 15 kOe, values higher than those obtained for Sm2(Fe,M)17 carbides.

Molecular dynamics of the frame-shifting pseudoknot from beet western yellows virus: the role of non-Watson-Crick base-pairing, ordered hydration, cation binding and base mutations on stability and unfolding.

PubMed

Csaszar, K; Spacková, N; Stefl, R; Sponer, J; Leontis, N B

2001-11-09

Molecular dynamics simulations of the frame-shifting pseudoknot from beet western yellows virus (BWYV, NDB file UR0004) were performed with explicit inclusion of solvent and counterions. In all, 33 ns of simulation were carried out, including 10 ns of the native structure with protonation of the crucial cytosine residue, C8(N3+). The native structure exhibited stable trajectories retaining all Watson-Crick and tertiary base-pairs, except for fluctuations or transient disruptions at specific sites. The most significant fluctuations involved the change or disruption of hydrogen-bonding between C8(N3+) and bases G12, A25, and C26, as well as disruption of the water bridges linking C8(N3+) with A25 and C26. To increase sampling of rare events, the native simulation was continued at 400 K. A partial, irreversible unfolding of the molecule was initiated by slippage of C8(N3+) relative to G12 and continued by sudden concerted changes in hydrogen-bonding involving A23, A24, and A25. These events were followed by a gradual loss of stacking interactions in loop 2. Of the Watson-Crick base-pairs, only the 5'-terminal pair of stem 1 dissociated at 400 K, while the trans sugar-edge/sugar-edge A20.G4 interaction remained surprisingly stable. Four additional room-temperature simulations were carried out to obtain insights into the structural and dynamic effects of selected mutations. In two of these, C8 was left unprotonated. Considerable local rearrangements occurred that were not observed in the crystal structure, thus confirming N3-protonation of C8 in the native molecule. We also investigated the effect of mutating C8(N3+) to U8, to correlate with experimental and phylogenetic studies, and of changing the G4 x C17 base-pair to A4 x U17 to weaken the trans sugar-edge interaction between positions 4 and 20 and to test models of unfolding. The simulations indicate that the C8 x G12 x C26 base-triple at the junction is the most labile region of the frame-shifting pseudoknot. They provide insights into the roles of the other non-Watson-Crick base-pairs in the early stages of unfolding of the pseudoknot, which must occur to allow readthrough of the message by the ribosome. The simulations revealed several critical, highly ordered hydration sites with close to 100 % occupancies and residency times of individual water molecules of up to 5 ns. Sodium cation coordination sites with occupancies above 50 % were also observed. Copyright 2001 Academic Press.

Electrical and Optical Properties of Nanocrystalline A8ZnNb6O24 (A = Ba, Sr, Ca, Mg) Ceramics

NASA Astrophysics Data System (ADS)

John, Fergy; Thomas, Jijimon K.; Jacob, John; Solomon, Sam

2017-08-01

Nanoparticles of A8ZnNb6O24 (A = Ba, Sr, Ca, and Mg, abbreviated as BZN, SZN, CZN, and MZN) have been synthesized by an auto-igniting combustion technique and their structural and optical properties characterized. The phase purity, crystal structure, and particle size of the prepared nanopowders were examined by x-ray diffraction (XRD) analysis and transmission electron microscopy. The XRD results revealed that all the samples crystallized with hexagonal perovskite structure in space group P6 3 cm. The Fourier-transform infrared and Raman (FT-Raman) spectra of the samples were investigated in detail. The ultraviolet-visible (UV-Vis) absorption spectra of the samples were also recorded and their optical bandgap energy values calculated. The nanopowders synthesized by the combustion technique were sintered to 95% of theoretical density at temperature of 1250°C for 2 h. The surface morphology of the sintered pellets was studied by scanning electron microscopy. The photoluminescence spectra of the samples showed intense emission in the blue-green region. Complex impedance analysis was used to determine the grain and grain boundary effects on the dielectric behavior of the ceramics.

Substituent Effects In a Series of 1,7-C60(RF)2 Compounds (RF = CF3, C2F5, n-C3F7, i-C3F7, n-C4F9, s-C4F9, n-C8F17): Electron Affinities, Reduction Potentials, and E(LUMO) Values Are Not Always Correlated

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

Kuvychko, Igor V.; Whitaker, James B.; Larson, Bryon W.

Substituent effects are of paramount importance in virtually all fields of fundamental and applied chemistry. Classical and modern examples can be found in organic chemistry (Hammett parameters and Charton steric parameters), inorganic chemistry (trans effect and trans influence), organometallic chemistry (phosphine cone angles), physical chemistry (linear free energy relationships and DFT), biochemistry (protein tertiary structure), medicinal chemistry (SAR maps and BioMAP analysis), polymer chemistry (nonlinear optical and permeation properties and glass transition temperatures), and materials chemistry (stability and luminescent properties of electroluminescent devices and light-to-power conversion efficiencies of fullerene-derivative-based OPV devices).

Batisite, Na2BaTi2(Si4O12)O2, from Inagli massif, Aldan, Russia: crystal-structure refinement and high-temperature X-ray diffraction study

NASA Astrophysics Data System (ADS)

Zolotarev, Andrey A.; Zhitova, Elena S.; Gabdrakhmanova, Faina A.; Krzhizhanovskaya, Maria G.; Zolotarev, Anatoly A.; Krivovichev, Sergey V.

2017-12-01

The crystal structure of batisite, Na2BaTi2 (Si4O12)O2, from the Inagli massif (Aldan, Yakutia, Russia) was refined to R 1 = 0.032 for 1449 unique observed reflections. The mineral is orthorhombic, Imma, a = 8.0921(5), b = 10.4751(7), c = 13.9054(9) Å, V = 1178.70(13) Å3. The mineral is based upon three-dimensional titanosilicate framework consisting of chains of corner-sharing MO6 octahedra ( M = Ti, Nb, Fe and Zr) and vierer chains of corner-sharing SiO4 tetrahedra. Both chains are parallel to the a axis and are linked by sharing peripheral O atoms. The octahedral chains display disorder of M atoms and bridging O sites related to the out-of-center distortion of octahedral geometry around Ti4+ cations. Electron microprobe analysis gives SiO2 39.46, TiO2 24.66, BaO 21.64, Na2O 7.56, K2O 4.38, Fe2O3 0.90, ZrO2 0.66, Nb2O5 0.36, (H2O)calc 0.58, sum 99.76 wt%. The seven strongest X-ray powder-diffraction lines [listed as d in Å (I) hkl] are: 8.39 (94) 011, 3.386 (56) 031, 3.191 (36) 123, 2.910 (46) 222, 2.896 (100) 024, 2.175 (45) 035, 1.673 (57) 055. The thermal behaviour of batisite in the temperature range from 25 to 950 °C was studied using high-temperature powder X-ray diffraction. The thermal expansion coefficients along the principal crystallographic axes are: α a = 14.4 × 10-6, α b = 8.7 × 10-6, α c = 8.4 × 10-6, α V = 31.5 °C-1 for the temperature range 25-500 °C and α a = 19.6 × 10-6, α b = 9.1 × 10-6, α c = 8.8 × 10-6, α V = 37.6 °C-1 for the temperature range 500-900 °C. The direction of maximal thermal expansion is parallel to the chains of both MO6 octahedra and SiO4 tetrahedra, which can be explained by the stretching of silicate chains due to the increasing thermal vibrations of the Ba2+ cations. At 1000 °C, the titanosilicate framework in batisite collapses with the formation of fresnoite, Ba2TiSi2O7O.

Phase behavior of 1-dodecyl-3-methylimidazolium fluorohydrogenate salts (C12MIm(FH)(n)F, n = 1.0-2.3) and their anisotropic ionic conductivity as ionic liquid crystal electrolytes.

PubMed

Xu, Fei; Matsumoto, Kazuhiko; Hagiwara, Rika

2012-08-23

The effects of the HF composition, n, in 1-dodecyl-3-methylimidazolium fluorohydrogenate salts (C(12)MIm(FH)(n)F, n = 1.0-2.3) on their physicochemical and structural properties have been investigated using infrared spectroscopy, thermal analysis, polarized optical microscopy, X-ray diffraction, and anisotropic ionic conductivity measurements. The phase diagram of C(12)MIm(FH)(n)F (n vs transition temperature) suggests that C(12)MIm(FH)(n)F is a mixed crystal system that has a boundary around n = 1.9. For all compositions, a liquid crystalline mesophase with a smectic A interdigitated bilayer structure is observed. The temperature range of the mesophase decreases with increasing n value (from 61.8 °C for C(12)MIm(FH)(1.0)F to 37.0 °C for C(12)MIm(FH)(2.3)F). The layer spacing of the smectic structure decreases with increasing n value or increasing temperature. Two structural types with different layer spacings are observed in the crystalline phase (type I, 1.0 ≤ n ≤ 1.9, and type II, 1.9 ≤ n ≤ 2.3). Ionic conductivities parallel and perpendicular to the smectic layers (σ(||) and σ([perpendicular])) increase with increasing n value, whereas the anisotropy of the ionic conductivities (σ(||)/σ([perpendicular])) is independent of the n value, since the thickness of the insulating sheet formed by the dodecyl group remains nearly unchanged.

Electron transfer flavoprotein domain II orientation monitored using double electron-electron resonance between an enzymatically reduced, native FAD cofactor, and spin labels

PubMed Central

Swanson, Michael A; Kathirvelu, Velavan; Majtan, Tomas; Frerman, Frank E; Eaton, Gareth R; Eaton, Sandra S

2011-01-01

Human electron transfer flavoprotein (ETF) is a soluble mitochondrial heterodimeric flavoprotein that links fatty acid β-oxidation to the main respiratory chain. The crystal structure of human ETF bound to medium chain acyl-CoA dehydrogenase indicates that the flavin adenine dinucleotide (FAD) domain (αII) is mobile, which permits more rapid electron transfer with donors and acceptors by providing closer access to the flavin and allows ETF to accept electrons from at least 10 different flavoprotein dehydrogenases. Sequence homology is high and low-angle X-ray scattering is identical for Paracoccus denitrificans (P. denitrificans) and human ETF. To characterize the orientations of the αII domain of P. denitrificans ETF, distances between enzymatically reduced FAD and spin labels in the three structural domains were measured by double electron-electron resonance (DEER) at X- and Q-bands. An FAD to spin label distance of 2.8 ± 0.15 nm for the label in the FAD-containing αII domain (A210C) agreed with estimates from the crystal structure (3.0 nm), molecular dynamics simulations (2.7 nm), and rotamer library analysis (2.8 nm). Distances between the reduced FAD and labels in αI (A43C) were between 4.0 and 4.5 ± 0.35 nm and for βIII (A111C) the distance was 4.3 ± 0.15 nm. These values were intermediate between estimates from the crystal structure of P. denitrificans ETF and a homology model based on substrate-bound human ETF. These distances suggest that the αII domain adopts orientations in solution that are intermediate between those which are observed in the crystal structures of free ETF (closed) and ETF bound to a dehydrogenase (open). PMID:21308847

Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu 3–xSe 2

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

Rettie, Alexander J. E.; Sturza, Mihai; Malliakas, Christos D.

The two-dimensional material KCu 3–xSe 2 was synthesized using both a K 2Se 3 flux and directly from the elements. It crystallizes in the CsAg 3S 2 structure (monoclinic space group C2/m with a = 15.417(3) Å, b = 4.0742(8) Å, c = 8.3190(17) Å, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu 3–xSe 2]– layers separated by K + ions. Thermal analysis indicated that KCu 3–xSe 2 melts congruently at ~755 °C. UV–vis spectroscopy showed an optical band gap of ~1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurementsmore » on single crystals yielded an in-plane resistivity of ~6 × 10 –1 Ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K –1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm 2 V –1 s –1) holes caused by relatively flat valence bands with substantial Cu 3d character and a significant concentration of Cu ion vacancy defects (p ~ 10 19 cm –3) in this material. In conclusion, electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.« less

Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu 3–xSe 2

DOE PAGES

Rettie, Alexander J. E.; Sturza, Mihai; Malliakas, Christos D.; ...

2017-06-21

The two-dimensional material KCu 3–xSe 2 was synthesized using both a K 2Se 3 flux and directly from the elements. It crystallizes in the CsAg 3S 2 structure (monoclinic space group C2/m with a = 15.417(3) Å, b = 4.0742(8) Å, c = 8.3190(17) Å, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu 3–xSe 2]– layers separated by K + ions. Thermal analysis indicated that KCu 3–xSe 2 melts congruently at ~755 °C. UV–vis spectroscopy showed an optical band gap of ~1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurementsmore » on single crystals yielded an in-plane resistivity of ~6 × 10 –1 Ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K –1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm 2 V –1 s –1) holes caused by relatively flat valence bands with substantial Cu 3d character and a significant concentration of Cu ion vacancy defects (p ~ 10 19 cm –3) in this material. In conclusion, electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.« less

Characterization of Capsicum annuum Genetic Diversity and Population Structure Based on Parallel Polymorphism Discovery with a 30K Unigene Pepper GeneChip

PubMed Central

Hill, Theresa A.; Ashrafi, Hamid; Reyes-Chin-Wo, Sebastian; Yao, JiQiang; Stoffel, Kevin; Truco, Maria-Jose; Kozik, Alexander; Michelmore, Richard W.; Van Deynze, Allen

2013-01-01

The widely cultivated pepper, Capsicum spp., important as a vegetable and spice crop world-wide, is one of the most diverse crops. To enhance breeding programs, a detailed characterization of Capsicum diversity including morphological, geographical and molecular data is required. Currently, molecular data characterizing Capsicum genetic diversity is limited. The development and application of high-throughput genome-wide markers in Capsicum will facilitate more detailed molecular characterization of germplasm collections, genetic relationships, and the generation of ultra-high density maps. We have developed the Pepper GeneChip® array from Affymetrix for polymorphism detection and expression analysis in Capsicum. Probes on the array were designed from 30,815 unigenes assembled from expressed sequence tags (ESTs). Our array design provides a maximum redundancy of 13 probes per base pair position allowing integration of multiple hybridization values per position to detect single position polymorphism (SPP). Hybridization of genomic DNA from 40 diverse C. annuum lines, used in breeding and research programs, and a representative from three additional cultivated species (C. frutescens, C. chinense and C. pubescens) detected 33,401 SPP markers within 13,323 unigenes. Among the C. annuum lines, 6,426 SPPs covering 3,818 unigenes were identified. An estimated three-fold reduction in diversity was detected in non-pungent compared with pungent lines, however, we were able to detect 251 highly informative markers across these C. annuum lines. In addition, an 8.7 cM region without polymorphism was detected around Pun1 in non-pungent C. annuum. An analysis of genetic relatedness and diversity using the software Structure revealed clustering of the germplasm which was confirmed with statistical support by principle components analysis (PCA) and phylogenetic analysis. This research demonstrates the effectiveness of parallel high-throughput discovery and application of genome-wide transcript-based markers to assess genetic and genomic features among Capsicum annuum. PMID:23409153

Characterization of Capsicum annuum genetic diversity and population structure based on parallel polymorphism discovery with a 30K unigene Pepper GeneChip.

PubMed

Hill, Theresa A; Ashrafi, Hamid; Reyes-Chin-Wo, Sebastian; Yao, JiQiang; Stoffel, Kevin; Truco, Maria-Jose; Kozik, Alexander; Michelmore, Richard W; Van Deynze, Allen

2013-01-01

The widely cultivated pepper, Capsicum spp., important as a vegetable and spice crop world-wide, is one of the most diverse crops. To enhance breeding programs, a detailed characterization of Capsicum diversity including morphological, geographical and molecular data is required. Currently, molecular data characterizing Capsicum genetic diversity is limited. The development and application of high-throughput genome-wide markers in Capsicum will facilitate more detailed molecular characterization of germplasm collections, genetic relationships, and the generation of ultra-high density maps. We have developed the Pepper GeneChip® array from Affymetrix for polymorphism detection and expression analysis in Capsicum. Probes on the array were designed from 30,815 unigenes assembled from expressed sequence tags (ESTs). Our array design provides a maximum redundancy of 13 probes per base pair position allowing integration of multiple hybridization values per position to detect single position polymorphism (SPP). Hybridization of genomic DNA from 40 diverse C. annuum lines, used in breeding and research programs, and a representative from three additional cultivated species (C. frutescens, C. chinense and C. pubescens) detected 33,401 SPP markers within 13,323 unigenes. Among the C. annuum lines, 6,426 SPPs covering 3,818 unigenes were identified. An estimated three-fold reduction in diversity was detected in non-pungent compared with pungent lines, however, we were able to detect 251 highly informative markers across these C. annuum lines. In addition, an 8.7 cM region without polymorphism was detected around Pun1 in non-pungent C. annuum. An analysis of genetic relatedness and diversity using the software Structure revealed clustering of the germplasm which was confirmed with statistical support by principle components analysis (PCA) and phylogenetic analysis. This research demonstrates the effectiveness of parallel high-throughput discovery and application of genome-wide transcript-based markers to assess genetic and genomic features among Capsicum annuum.

Cloning of developmentally regulated flagellin genes from Caulobacter crescentus via immunoprecipitation of polyribosomes.

PubMed Central

Milhausen, M; Gill, P R; Parker, G; Agabian, N

1982-01-01

Immunoprecipitation of Caulobacter crescentus polyribosomes with antiflagellin antibody provided RNA for the synthesis of cDNA probes that were used to identify three specific EcoRI restriction fragments (6.8, 10, and 22 kilobases) in genomic digests of Caulobacter DNA. The RNA was present only in polyribosomes isolated from a time interval in the Caulobacter cell cycle that was coincident with flagellin polypeptide synthesis. The structural gene for Mr 27,500 flagellin polypeptide was assigned to a region of the 10-kilobase EcoRI restriction fragment by DNA sequence analysis. Analysis of mutants defective in motility further established a correlation between the Mr 27,500 flagellin gene and the flaE gene locus [Johnson, R. C. & Ely, B. (1979) J. Bacteriol. 137, 627-634]. The other EcoRI fragments that hybridize with the immunoprecipitated polyribosome-derived cDNA probe are also temporally regulated and have features that suggest they encode other polypeptides associated with the flagellum. Modifications were required to adapt the procedure of immunoprecipitation of polyribosomes for use with Caulobacter and should be applicable to the production of specific structural gene probes from other prokaryotic systems. Images PMID:6294658

Community structure and soil pH determine chemoautotrophic carbon dioxide fixation in drained paddy soils.

PubMed

Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

2015-06-16

Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem.

Rational Design Synthesis and Evaluation of First Generation Inhibitors of the Giardia Lamblia Fructose-1 6-biphosphate Aldolase

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

Z Li; Z Liu; D Cho

2011-12-31

Inhibitors of the Giardia lamblia fructose 1,6-bisphosphate aldolase (GlFBPA), which transforms fructose 1,6-bisphosphate (FBP) to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, were designed based on 3-hydroxy-2-pyridone and 1,2-dihydroxypyridine scaffolds that position two negatively charged tetrahedral groups for interaction with substrate phosphate binding residues, a hydrogen bond donor to the catalytic Asp83, and a Zn{sup 2+} binding group. The inhibition activities for the GlFBPA catalyzed reaction of FBP of the prepared alkyl phosphonate/phosphate substituted 3-hydroxy-2-pyridinones and a dihydroxypyridine were determined. The 3-hydroxy-2-pyridone inhibitor 8 was found to bind to GlFBPA with an affinity (K{sub i} = 14 {micro}M) that is comparable tomore » that of FBP (K{sub m} = 2 {micro}M) or its inert analog TBP (K{sub i} = 1 {micro}M). The X-ray structure of the GlFBPA-inhibitor 8 complex (2.3 {angstrom}) shows that 8 binds to the active site in the manner predicted by in silico docking with the exception of coordination with Zn{sup 2+}. The observed distances and orientation of the pyridone ring O=C-C-OH relative to Zn{sup 2+} are not consistent with a strong interaction. To determine if Zn{sup 2+} coordination occurs in the GlFBPA-inhibitor 8 complex in solution, EXAFS spectra were measured. A four coordinate geometry comprised of the three enzyme histidine ligands and an oxygen atom from the pyridone ring O=C-C-OH was indicated. Analysis of the Zn{sup 2+} coordination geometries in recently reported structures of class II FBPAs suggests that strong Zn{sup 2+} coordination is reserved for the enediolate-like transition state, accounting for minimal contribution of Zn{sup 2+} coordination to binding of 8 to GlFBPA.« less

Rational design, synthesis and evaluation of first generation inhibitors of the Giardia lamblia fructose-1,6-biphosphate aldolase.

PubMed

Li, Zhimin; Liu, Zhengang; Cho, Dae Won; Zou, Jiwen; Gong, Maozhen; Breece, Robert M; Galkin, Andrey; Li, Ling; Zhao, Hong; Maestas, Gabriel D; Tierney, David L; Herzberg, Osnat; Dunaway-Mariano, Debra; Mariano, Patrick S

2011-04-01

Inhibitors of the Giardia lamblia fructose 1,6-bisphosphate aldolase (GlFBPA), which transforms fructose 1,6-bisphosphate (FBP) to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, were designed based on 3-hydroxy-2-pyridone and 1,2-dihydroxypyridine scaffolds that position two negatively charged tetrahedral groups for interaction with substrate phosphate binding residues, a hydrogen bond donor to the catalytic Asp83, and a Zn(2+) binding group. The inhibition activities for the GlFBPA catalyzed reaction of FBP of the prepared alkyl phosphonate/phosphate substituted 3-hydroxy-2-pyridinones and a dihydroxypyridine were determined. The 3-hydroxy-2-pyridone inhibitor 8 was found to bind to GlFBPA with an affinity (K(i)=14μM) that is comparable to that of FBP (K(m)=2μM) or its inert analog TBP (K(i)=1μM). The X-ray structure of the GlFBPA-inhibitor 8 complex (2.3Å) shows that 8 binds to the active site in the manner predicted by in silico docking with the exception of coordination with Zn(2+). The observed distances and orientation of the pyridone ring O=C-C-OH relative to Zn(2+) are not consistent with a strong interaction. To determine if Zn(2+)coordination occurs in the GlFBPA-inhibitor 8 complex in solution, EXAFS spectra were measured. A four coordinate geometry comprised of the three enzyme histidine ligands and an oxygen atom from the pyridone ring O=C-C-OH was indicated. Analysis of the Zn(2+) coordination geometries in recently reported structures of class II FBPAs suggests that strong Zn(2+) coordination is reserved for the enediolate-like transition state, accounting for minimal contribution of Zn(2+) coordination to binding of 8 to GlFBPA. Copyright © 2010 Elsevier Inc. All rights reserved.

Hydrothermal synthesis of zinc(II)-phosphonate coordination polymers with different dimensionality (0D, 2D, 3D) and dimensionality change in the solid phase (0D→3D) induced by temperature

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

Fernández-Zapico, Eva; Montejo-Bernardo, Jose; Fernández-González, Alfonso

2015-05-15

Three new zinc(II) coordination polymers, [Zn(HO{sub 3}PCH{sub 2}CH{sub 2}COO)(C{sub 12}H{sub 8}N{sub 2})(H{sub 2}O)] (1), [Zn{sub 3}(O{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(C{sub 12}H{sub 8}N{sub 2})](H{sub 2}O){sub 3.40} (2) and [Zn{sub 5}(HO{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(O{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(C{sub 12}H{sub 8}N{sub 2}){sub 4}](H{sub 2}O){sub 0.32} (3), with different structural dimensionality (0D, 2D and 3D, respectively) have been prepared by hydrothermal synthesis, and their structures were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system (P2{sub 1}/c) forming discrete dimeric units bonded through H-bonds, while compounds 2 and 3 crystallize in the triclinic (P−1) and the monoclinic (C2/c) systems, respectively.more » Compound 3, showing three different coordination numbers (4, 5 and 6) for the zinc atoms, has also been obtained by thermal treatment of 1 (probed by high-temperature XRPD experiments). The crystalline features of these compounds, related to the coordination environments for the zinc atoms in each structure, provoke the increase of the relative fluorescence for 2 and 3, compared to the free phenanthroline. Thermal analysis (TG and DSC) and XPS studies have been also carried out for all compounds. - Graphical abstract: Three new coordination compounds of zinc with 2-carboxyethylphosphonic acid (H{sub 2}PPA) and phenanthroline have been obtained by hydrothermal synthesis. The crystalline structure depends on the different coordination environments of the zinc atoms (see two comparative Zn{sub 6}-moieties). The influence of the different coordination modes of H{sub 2}PPA with the central atom in all structures have been studied, being found new coordination modes for this ligand. Several compounds show a significant increase in relative fluorescence with respect to the free phenanthroline. - Highlights: • Compounds have been obtained modifying the reaction time and the rate of reagents. • Dimensionality and crystalline structure is a function of the zinc environments. • New coordination modes for 2-carboxyethylphosphonic acid are reported. • 3D-compound presents three different coordination environments for the zinc atoms. • Fluorescence properties are related to the structural dimensionality.« less

Gold(III) bis-thiosemicarbazonato complexes: synthesis, characterization, radiochemistry and X-ray crystal structure analysis.

PubMed

Bottenus, Brienne N; Kan, Para; Jenkins, Tyler; Ballard, Beau; Rold, Tammy L; Barnes, Charles; Cutler, Cathy; Hoffman, Timothy J; Green, Mark A; Jurisson, Silvia S

2010-01-01

A variety of (bis)thiosemicarbazone-based ligand systems have been investigated as chelating agents for Au(III) complexes with potential radiotherapeutic applications. Ligand systems containing an ethyl, propyl or butyl backbone between the two imine N donors have been synthesized to evaluate chelate ring size effects on the resultant Au(III) complex stability at the macroscopic and radiotracer levels. The Au(III) complexes were synthesized and characterized by NMR, electrospray ionization mass spectra, elemental analysis and X-ray crystallography. The (198)Au complexes were evaluated in vitro at the tracer level for stability in phosphate-buffered saline at pH 7.4 and 37 degrees C. One of these complexes [(198)Au(3,4-HxTSE)] showed high in vitro stability and was further evaluated in vivo in normal mice. [Au(ATSM)]AuCl(4).2CH(3)OH, (ATSM=diacetyl-bis(N(4)-methylthiosemicarbazone)) H(14)C(8)N(6)O(2)S(2)Cl(4)Au(2).2CH(3)OH, crystallized from methanol in the monoclinic space group P21/n with a=14.7293(13) A, b=7.7432(7) A, c=20.4363(18) A, beta=100.140(2) degrees, V=2294.4 (4) A(3), Z=4; [Au(3,4-HxTSE)]Cl.CH(3)CH(2)OH/AuCl(2), (3,4-HxTSE=3,4-hexanedione-bis(N(4)-ethylthiosemicarbazone)) H(26)C(13.6)N(6)O(0.8)S(2)Cl(1.2)Au(1.2), crystallized from ethanol in the monoclinic space group P21/c with a=10.1990(10) A, b=13.8833(14) A, c=15.1752(15) A, beta=99.353(2) degrees , V=2120.2 (4) A(3), Z=4. These studies revealed poor stability of the [(198)Au][Au(3,4-HxTSE)](+) complex; however, crystal structure data suggest potential alterations to the ligand backbone may increase stability. Copyright 2010 Elsevier Inc. All rights reserved.

Single-crystal growth, structure refinement and the properties of Bis(glycine) Strontium Chloride

NASA Astrophysics Data System (ADS)

Balaji, S. R.; Balu, T.; Rajasekaran, T. R.

2018-02-01

Single crystals of Bis (glycine) Strontium Chloride (BGSC) were grown by means of slow evaporation process by using analar grade Glycine and Strontium Chloride Hexahydrate as a parent compound from its aqueous solution at room temperature. The final chemical composition, [{{Sr}}{({{{C}}}2{{{H}}}5{{{NO}}}2)}2{{{Cl}}}2].{{{H}}}4{{{O}}}3+{{{H}}}8{{{O}}}3, formed were metallic light colorless block, about the size of 28 mm × 9 mm × 8 mm. A single-crystal x-ray diffraction study revealed an ordered superstructure with orthorhombic symmetry that could be assigned to the space group Pbcn. The structure in BGSC, revealed in the electron density distribution was analyzed by the direct methods (SHELXS-2014) and refined by least squares full matrix method (SHELXL-2014). The crystal structure, including anisotropic atomic displacement parameters for each atom and isotropic atomic displacement parameters for hydrogen atom, was refined to R1 = 0.0395, wR2 = 0.0776 using 1097 independent reflections. The FTIR spectrum of BGSC confirms the protonation of amino groups and the different molecular groups present in BGSC vibrate in different modes. Reverse Indentation Size Effect (RISE) was revealed in BGSC in the micro-hardness analysis using Vicker’s micro-hardness analysis. DTA and DSC results ruled out the possibility of structural change independent of mass change. The AFM studies shows fine nano size fiber like structure of the grown crystals.

Structure and Luminescence Properties of New Green-Emitting Phosphor BaAl12O19:Tb

NASA Astrophysics Data System (ADS)

Xiao, Linjiu; He, Mingrui; Tian, Yanwen; Chen, Yongjie; Karaki, Tomoaki; Zhang, Liqing; Wang, Ning

2007-09-01

New green-emitting BaAl12O19:Tb phosphors were prepared by using the sol-gel method, and their structure and luminescence property were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry. The results of XRD analysis revealed that a Ba1-xAl12O19:Tbx crystal structure was obtained at 1300 °C and Tb3+ ions substituted Ba2+ ions into the BaAl12O19 phase in the ion range x=0.005--0.05. The excitation peak of BaAl12O19:Tb was a wide band at approximately 240 nm, originating from the 4 f8-4 f75d1 transition of Tb3+. The emission spectrum consisted of eight emission peaks, originating from the 5D3-7Fi (i=6,5,4,3) and 5D4-7Fj ( j=6,5,4,3) transitions of Tb3+. The emission intensity of BaAl12O19:Tb phosphors at 543 nm was strongest when the phosphors were crystallized at 1300 °C for 2 h, and the content of Tb3+ was 2 mol %.

Tunable thermo-responsive hydrogels: synthesis, structural analysis and drug release studies.

PubMed

Cirillo, Giuseppe; Spataro, Tania; Curcio, Manuela; Spizzirri, U Gianfranco; Nicoletta, Fiore Pasquale; Picci, Nevio; Iemma, Francesca

2015-03-01

Thermo-responsive hydrogel films, synthesized by UV-initiated radical polymerization, are proposed as delivery devices for non-steroidal anti-inflammatory drugs (Diclofenac sodium and Naproxen). N-isopropylacrylamide and N,N'-ethylenebisacrylamide were chosen as thermo-sensitive monomer and crosslinker, respectively. Infrared spectroscopy was used to assess the incorporation of monomers into the network, and the network density of hydrogel films was found to strictly depend on both feed composition and film thickness. Calorimetric analyses showed negative thermo-responsive behaviour with shrinking/swelling transition values in the range 32.8-36.1°C. Equilibrium swelling studies around the LCST allowed the correlation between the structural changes and the temperature variations. The mesh size, indeed, rapidly changed from a collapsed to a swollen state, with beneficial effects in applications such as size-selective permeation or controlled drug delivery, while the crosslinking degree, the film thickness, and the loading method deeply influenced the drug release profiles at 25 and 40°C. The analysis of both 3D-network structure, release kinetics and diffusional constraints at different temperatures was evaluated by mathematical modelling. Copyright © 2014 Elsevier B.V. All rights reserved.

The complete mitochondrial genome of the armored catfish, Hypostomus plecostomus (Siluriformes: Loricariidae).

PubMed

Liu, Shikai; Zhang, Jiaren; Yao, Jun; Liu, Zhanjiang

2016-05-01

The complete mitochondrial genome of the armored catfish, Hypostomus plecostomus, was determined by next generation sequencing of genomic DNA without prior sample processing or primer design. Bioinformatics analysis resulted in the entire mitochondrial genome sequence with length of 16,523 bp. The H. plecostomus mitochondrial genome is consisted of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 1 control region, showing typical circular molecule structure of mitochondrial genome as in other vertebrates. The whole genome base composition was estimated to be 31.8% A, 27.0% T, 14.6% G, and 26.6% C, with A/T bias of 58.8%. This work provided the H. plecostomus mitochondrial genome sequence which should be valuable for species identification, phylogenetic analysis and conservation genetics studies in catfishes.

Benzylic oxidation of gemfibrozil-1-O-beta-glucuronide by P450 2C8 leads to heme alkylation and irreversible inhibition.

PubMed

Baer, Brian R; DeLisle, Robert Kirk; Allen, Andrew

2009-07-01

Gemfibrozil-1-O-beta-glucuronide (GEM-1-O-gluc), a major metabolite of the antihyperlipidemic drug gemfibrozil, is a mechanism-based inhibitor of P450 2C8 in vitro, and this irreversible inactivation may lead to clinical drug-drug interactions between gemfibrozil and other P450 2C8 substrates. In light of this in vitro finding and the observation that the glucuronide conjugate does not contain any obvious structural alerts, the current study was conducted to determine the potential site of GEM-1-O-gluc bioactivation and the subsequent mechanism of P450 2C8 inhibition (i.e., modification of apoprotein or heme). LC/MS analysis of a reaction mixture containing recombinant P450 2C8 and GEM-1-O-gluc revealed that the substrate was covalently linked to the heme prosthetic heme group during catalysis. A combination of mass spectrometry and deuterium isotope effects revealed that a benzylic carbon on the 2',5'-dimethylphenoxy group of GEM-1-O-gluc was covalently bound to the heme of P450 2C8. The regiospecificity of substrate addition to the heme group was not confirmed experimentally, but computational modeling experiments indicated that the gamma-meso position was the most likely site of modification. The metabolite profile, which consisted of two benzyl alcohol metabolites and a 4'-hydroxy-GEM-1-O-gluc metabolite, indicated that oxidation of GEM-1-O-gluc was limited to the 2',5'-dimethylphenoxy group. These results are consistent with an inactivation mechanism wherein GEM-1-O-gluc is oxidized to a benzyl radical intermediate, which evades oxygen rebound, and adds to the gamma-meso position of heme. Mechanism-based inhibition of P450 2C8 can be rationalized by the formation of the GEM-1-O-gluc-heme adduct and the consequential restriction of additional substrate access to the catalytic iron center.

High-Pressure Synthesis and Characterization of the Ammonium Yttrium Borate (NH4)YB8O14.

PubMed

Schmitt, Martin K; Podewitz, Maren; Liedl, Klaus R; Huppertz, Hubert

2017-11-20

The first high-pressure yttrium borate (NH 4 )YB 8 O 14 was synthesized at 12.8 GPa/1300 °C using a Walker-type multianvil module. The compound crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 17.6375(9), b = 10.7160(5), and c = 4.2191(2) Å. (NH 4 )YB 8 O 14 constitutes a novel structure type but exhibits similarities to the crystal structure of β-BaB 4 O 7 . X-ray single-crystal and powder diffraction, EDX, vibrational spectroscopy as well as quantum chemical calculations were used to characterize (NH 4 )YB 8 O 14 .

Halogen Oxygen Interactions and Disorder Modes in Pressure Frozen Complexes of 1,2-Dihaloperfluoroethanes with 1,4-Dioxane (Preprint)

DTIC Science & Technology

2007-05-17

iodoperfluoroethanes in 1:1 mixtures with 1,4-dioxane were pressure frozen in a diamond-anvil cell. Structures of cocrystal of 1,2...GPa/296 K. The cocrystal of ICF2CF2I:C4H8O2 and the 1,4-dioxane crystals are isostructural with their phases frozen by cooling; the...BrCF2CF2I:C4H8O2 cocrystal has not been reported earlier. In the structure of ICF2CF2I:C4H8O2 the –CF2-CF2-moiety is disordered about the I˙˙˙I molecular axis and

Chaetoglobosins from Chaetomium globosum, an endophytic fungus in Ginkgo biloba, and their phytotoxic and cytotoxic activities.

PubMed

Li, He; Xiao, Jian; Gao, Yu-Qi; Tang, Jiang Jiang; Zhang, An-Ling; Gao, Jin-Ming

2014-04-30

In preceding studies, cultivation of Chaetomium globosum, an endophytic fungus in Ginkgo biloba, produced five cytochalasan mycotoxins, chaetoglobosins A, G, V, Vb, and C (1-5), in three media. In the present work, five known chaetoglobosins, C, E, F, Fex, and 20-dihydrochaetoglobosin A (5-9), together with the four known compounds (11-14), were isolated from the MeOH extracts of the solid culture of the same endophyte. The structures of these metabolites were elucidated on the basis of spectroscopic analysis. Treatment of chaetoglobosin F (7) with (diethylamino)sulfur trifluoride (DAST) in dichloromethane afforded an unexpected fluorinated chaetoglobosin, named chaetoglobosin Fa (10), containing an oxolane ring between C-20 and C-23. The phytotoxic effects of compounds 1, 3-8, and 10 were assayed on radish seedlings; some of these compounds (1, 3, and 6-8) significantly inhibited the growth of radish (Raphanus sativus) seedlings with inhibitory rates of >60% at a concentration of 50 ppm, which was comparable or superior to the positive control, glyphosate. In addition, the cytotoxic activities against HCT116 human colon cancer cells were also tested, and compounds 1 and 8-10 showed remarkable cytotoxicity with IC50 values ranging from 3.15 to 8.44 μM, in comparison to the positive drug etoposide (IC50 = 2.13 μM). The epoxide ring between C-6 and C-7 or the double bond at C-6(12) led to a drastically increased cytotoxicity, and chaetoglobosin Fa (10) displayed a markedly increased cytotoxicity but decreased phytotoxicity.

Structural analysis of DNA binding by C.Csp231I, a member of a novel class of R-M controller proteins regulating gene expression

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

Shevtsov, M. B.; Streeter, S. D.; Thresh, S.-J.

2015-02-01

The structure of the new class of controller proteins (exemplified by C.Csp231I) in complex with its 21 bp DNA-recognition sequence is presented, and the molecular basis of sequence recognition in this class of proteins is discussed. An unusual extended spacer between the dimer binding sites suggests a novel interaction between the two C-protein dimers. In a wide variety of bacterial restriction–modification systems, a regulatory ‘controller’ protein (or C-protein) is required for effective transcription of its own gene and for transcription of the endonuclease gene found on the same operon. We have recently turned our attention to a new class ofmore » controller proteins (exemplified by C.Csp231I) that have quite novel features, including a much larger DNA-binding site with an 18 bp (∼60 Å) spacer between the two palindromic DNA-binding sequences and a very different recognition sequence from the canonical GACT/AGTC. Using X-ray crystallography, the structure of the protein in complex with its 21 bp DNA-recognition sequence was solved to 1.8 Å resolution, and the molecular basis of sequence recognition in this class of proteins was elucidated. An unusual aspect of the promoter sequence is the extended spacer between the dimer binding sites, suggesting a novel interaction between the two C-protein dimers when bound to both recognition sites correctly spaced on the DNA. A U-bend model is proposed for this tetrameric complex, based on the results of gel-mobility assays, hydrodynamic analysis and the observation of key contacts at the interface between dimers in the crystal.« less

Evidence for co-operativity in coenzyme binding to tetrameric Sulfolobus solfataricus alcohol dehydrogenase and its structural basis: fluorescence, kinetic and structural studies of the wild-type enzyme and non-co-operative N249Y mutant.

PubMed

Giordano, Antonietta; Febbraio, Ferdinando; Russo, Consiglia; Rossi, Mosè; Raia, Carlo A

2005-06-01

The interaction of coenzyme with thermostable homotetrameric NAD(H)-dependent alcohol dehydrogenase from the thermoacidophilic sulphur-dependent crenarchaeon Sulfolobus solfataricus (SsADH) and its N249Y (Asn-249-->Tyr) mutant was studied using the high fluorescence sensitivity of its tryptophan residues Trp-95 and Trp-117 to the binding of coenzyme moieties. Fluorescence quenching studies performed at 25 degrees C show that SsADH exhibits linearity in the NAD(H) binding [the Hill coefficient (h) approximately 1) at pH 9.8 and at moderate ionic strength, in addition to positive co-operativity (h=2.0-2.4) at pH 7.8 and 6.8, and at pH 9.8 in the presence of salt. Furthermore, NADH binding is positively co-operative below 20 degrees C (h approximately 3) and negatively co-operative at 40-50 degrees C (h approximately 0.7), as determined at moderate ionic strength and pH 9.8. Steady-state kinetic measurements show that SsADH displays standard Michaelis-Menten kinetics between 35 and 45 degrees C, but exhibits positive and negative co-operativity for NADH oxidation below (h=3.3 at 20 degrees C) and above (h=0.7 at 70-80 degrees C) this range of temperatures respectively. However, N249Y SsADH displays non-co-operative behaviour in coenzyme binding under the same experimental conditions used for the wild-type enzyme. In loop 270-275 of the coenzyme domain and segments at the interface of dimer A-B, analyses of the wild-type and mutant SsADH structures identified the structural elements involved in the intersubunit communication and suggested a possible structural basis for co-operativity. This is the first report of co-operativity in a tetrameric ADH and of temperature-induced co-operativity in a thermophilic enzyme.

Arizona porphyry copper/hydrothermal deposits II: Crystal structure of ajoite, (K + Na)3Cu20Al3Si29O76(OH)16⋅∼8H2O

PubMed Central

Pluth, Joseph J.; Smith, Joseph V.

2002-01-01

A crystal from the type locality Ajo, AZ, yielded just enough intensity from streaked diffractions using synchrotron x-rays at the Advanced Photon Source to solve the crystal structure with composition (K + Na)3Cu20Al3Si29O76(OH)16⋅∼8H2O; triclinic, P1̄, a = 13.634(5) Å, b = 13.687(7), c = 14.522(7), α = 110.83(1)°, β = 107.21(1), γ = 105.68(1); refined to a final R = 12.5%. Electron microprobe analysis yielded a similar chemical composition that is slightly different from the combined chemical and electron microprobe analyses in the literature. The ajoite structure can be described as a zeolitic octahedral-tetrahedral framework that combines the alternate stacking of edge-sharing octahedral CuO6 layers and curved aluminosilicate layers and strings. Channels bounded by elliptical 12-rings and circular 8-rings of tetrahedra contain (K and Na) ions and water. The Al atoms occupy some of the Si tetrahedral sites. Each Cu atom has near-planar bonds to four oxygen atoms plus two longer distances that generate a distorted octahedron. Valence bond estimates indicate that 8 oxygen atoms of 46 are hydroxyl. Only one alkali atom was located in distorted octahedral coordination, and electron microprobe analyses indicate K and Na as major substituents. The water from chemical analysis presumably occurs as disordered molecules of zeolitic type not giving electron density from diffraction. The high R factor results from structural disorder and many weak intensities close to detection level. The crystal chemistry is compared with shattuckite, Cu5(SiO3)4(OH)2, and planchéite, Cu8Si8O22(OH)4⋅H2O, both found in oxidized copper deposits of Arizona but only the former directly with ajoite. PMID:12177404

Arizona porphyry copper/hydrothermal deposits II: crystal structure of ajoite, (K + Na)3Cu20Al3Si29O76(OH)16*~8H2O.

PubMed

Pluth, Joseph J; Smith, Joseph V

2002-08-20

A crystal from the type locality Ajo, AZ, yielded just enough intensity from streaked diffractions using synchrotron x-rays at the Advanced Photon Source to solve the crystal structure with composition (K + Na)3Cu20Al3Si29O76(OH)16* approximately 8H2O; triclinic, P1, a = 13.634(5) A, b = 13.687(7), c = 14.522(7), alpha = 110.83(1) degrees, beta = 107.21(1), gamma = 105.68(1); refined to a final R = 12.5%. Electron microprobe analysis yielded a similar chemical composition that is slightly different from the combined chemical and electron microprobe analyses in the literature. The ajoite structure can be described as a zeolitic octahedral-tetrahedral framework that combines the alternate stacking of edge-sharing octahedral CuO6 layers and curved aluminosilicate layers and strings. Channels bounded by elliptical 12-rings and circular 8-rings of tetrahedra contain (K and Na) ions and water. The Al atoms occupy some of the Si tetrahedral sites. Each Cu atom has near-planar bonds to four oxygen atoms plus two longer distances that generate a distorted octahedron. Valence bond estimates indicate that 8 oxygen atoms of 46 are hydroxyl. Only one alkali atom was located in distorted octahedral coordination, and electron microprobe analyses indicate K and Na as major substituents. The water from chemical analysis presumably occurs as disordered molecules of zeolitic type not giving electron density from diffraction. The high R factor results from structural disorder and many weak intensities close to detection level. The crystal chemistry is compared with shattuckite, Cu5(SiO3)4(OH)2, and planchéite, Cu8Si8O22(OH)4.H2O, both found in oxidized copper deposits of Arizona but only the former directly with ajoite.

Vibrational, NMR spectrum and orbital analysis of 3,3',5,5'-tetrabromobisphenol A: a combined experimental and computational study.

PubMed

Qiu, Shanshan; Wei, Jin; Pan, Feng; Liu, Jingping; Zhang, Aiqian

2013-03-15

In the present work, the experimental and theoretical studies on the structure, vibrations, NMR and HOMO-LUMO analysis of 3,3',5,5'-tetrabromobisphenol A (TBBPA) are presented. The FT-IR (400-4000 cm(-1)) and FT-Raman (100-4000 cm(-1)) spectra of TBBPA were recorded. The molecular geometry, vibrational frequencies were calculated by using density functional theory (DFT) method with the 6-31G(d) basis set. The optimized geometric properties, scaled vibrational wavenumbers, IR intensities, Raman activities show good agreement with the experimental data. The assigned vibrational modes of the IR and Raman spectra were compared with the corresponding properties of the polybrominated diphenyl ethers (PBDEs). Comparative analysis indicated that the red shift of C-Br vibration could probably be ascribed to the further electronic density equalization due to the p-π conjugation between O atom and the benzene. The natural bonding orbital (NBO) analysis demonstrated that the intermolecular hyperconjugative interactions are mainly formed by the orbital overlap between σ (O-H), σ(*) (C-C), π (C-C), π(*) (C-C) bond orbitals. Compared to the higher E((2)) value (33.65-34.82 kcal/mol) originated from LP(2)O to π(*) (C-C), the one (E((2)): 8.23-9.73 kcal/mol) from LP(3)Br and π(*) (C-C) contributes to the preferential tendency of C-Br breakage to the C-O breakage in the transformation. The calculated NMR results obtained on the 6-31G(d) level proves good agreement with the experimental data (r(2)=0.999). Analysis of isosurface of the related orbital shows that all the main excitation exhibit π-π(*) character localized on the benzene rings. Copyright © 2012 Elsevier B.V. All rights reserved.

PREFACE: Symposium 1: Advanced Structure Analysis and Characterization of Ceramic Materials

NASA Astrophysics Data System (ADS)

Yashima, Masatomo

2011-05-01

Preface to Symposium 1 (Advanced Structure Analysis and Characterization of Ceramic Materials) of the International Congress of Ceramics III, held 14-18 November 2010 in Osaka, Japan Remarkable developments have been made recently in the structural analysis and characterization of inorganic crystalline and amorphous materials, such as x-ray, neutron, synchrotron and electron diffraction, x-ray/neutron scattering, IR/Raman scattering, NMR, XAFS, first-principle calculations, computer simulations, Rietveld analysis, the maximum-entropy method, in situ measurements at high temperatures/pressures and electron/nuclear density analysis. These techniques enable scientists to study not only static and long-range periodic structures but also dynamic and short-/intermediate-range structures. Multi-scale characterization from the electron to micrometer levels is becoming increasingly important as a means of understanding phenomena at the interfaces, grain boundaries and surfaces of ceramic materials. This symposium has discussed the structures and structure/property relationships of various ceramic materials (electro, magnetic and optical ceramics; energy and environment related ceramics; bio-ceramics; ceramics for reliability secure society; traditional ceramics) through 38 oral presentations including 8 invited lectures and 49 posters. Best poster awards were given to six excellent poster presentations (Y-C Chen, Tokyo Institute of Technology; C-Y Chung, Tohoku University; T Stawski, University of Twente; Y Hirano, Nagoya Institute of Technology; B Bittova, Charles University Prague; Y Onodera, Kyoto University). I have enjoyed working with my friends in the ICC3 conference. I would like to express special thanks to other organizers: Professor Scott T Misture, Alfred University, USA, Professor Xiaolong Chen, Institute of Physics, CAS, China, Professor Takashi Ida, Nagoya Institute of Technology, Japan, Professor Isao Tanaka, Kyoto University, Japan. I also acknowledge the invited speakers, all the participants and organizing committee of the ICC3. I am pleased to publish the Proceedings of the Symposium 1 of ICC3. I hope that the papers contained in these Proceedings will prove helpful to Professors, researchers and students in improving the fields of Structure Analysis and Characterization of Ceramic Materials. Masatomo Yashima April 2011 Department of Chemistry and Materials Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, Japan

Quantifying intermolecular interactions in solid state indapamide and other popular diuretic drugs: Insights from Hirshfeld surface study

NASA Astrophysics Data System (ADS)

Bojarska, Joanna; Fruziński, Andrzej; Maniukiewicz, Waldemar

2016-07-01

Hirshfeld surfaces (HS) and two-dimensional fingerprint plots are used to analyze the intermolecular interactions in indapamide and other popular thiazide diuretic derivatives. The crystal structure of indapamide (INDP) at 100 K determined by single-crystal X-ray analysis, is also reported. The title compound crystallizes in the centrosymmetric I2/a space group with one indapamide and half water molecule (lying on the glide plane) in the asymmetric unit. An interplay of N-H⋯O hydrogen bonds connects the indapamide molecules generating chains with the graph-set motifs: C (8) and C23 (16), and together with C-H⋯O and π⋯π stacking interactions create a 3D net. The Hirshfeld surface study facilitates comparison of diverse and numerous intercontacts, such as H⋯H, O⋯H, Cl⋯H, C⋯C (π⋯π), C⋯O (π⋯lone pair), O⋯O (lone pair⋯lone pair), Cl⋯O, Cl⋯Cl, N⋯N, C⋯H (C-H⋯π) with regard to building self-assembled framework of indapamide and related thiazide derivatives retrieved from the Cambridge Structural Database. The HS analysis highlights that H⋯H, O⋯H/H⋯O and C⋯H/H⋯C contacts play an influential role contributing to about 80% of the HS areas in this class of compounds. Nevertheless, in the case of INDP the H⋯H interactions, while in hydrochlorothiazide (HCTZ) O⋯H/H⋯O are dominant amongst all intercontacts towards the HS. Notably, indapamide has the highest proportion of C⋯C contacts.

Lipid metabolites with free-radical scavenging activity from Euphorbia helioscopia L.

PubMed

Cateni, F; Zilic, J; Altieri, T; Zacchigna, M; Procida, G; Gaggeri, R; Rossi, D; Collina, S

2014-07-01

The methanolic extract of the plant Euphorbia helioscopia L. exhibited an interesting free-radical scavenging activity. From the aerial parts of Euphorbia helioscopia L. (Euphorbiaceae), a complex mixture of seven cerebrosides together with glucoclionasterol, a digalactosyldiacylglycerol and a diacylmonogalactosylglycerol were identified. The structures of the cerebrosides were characterized as 1-O-β-D-glucosides of phytosphingosines, which comprised (2S, 3S, 4E, 8E)-2-amino-4(E),8(E)-octadecadiene-1,3-diol, (2S, 3S, 4E, 8Z)-2-amino-4(E),8(Z)-octadecadiene-1,3-diol, (2S, 3S, 4R, 8Z)-2-amino-8(Z)-octadecene-1,3,4-triol as long chain bases with seven 2-hydroxy fatty acids of varying chain lengths (C16, C24:1, C26:1, C24, C26, C28:1) linked to the amino group. The glycosylglycerides were characterized as (2S)-2,3-O-di-(9,12,15-octadecatrienoyl)-glyceryl-6-O-(α-D-galactopyranosyl)-β-D-galactopyranoside and (2S)-2,3-O-di-(9,12,15-octadecatrienoyl)-glyceryl-1-O-β-D-galactopyranoside. The structures were established on the basis of spectroscopic data and chemical reactions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Propylene/propane permeation properties of ethyl cellulose (EC) mixed matrix membranes fabricated by incorporation of nanoporous graphene nanosheets

PubMed Central

Yuan, Bingbing; Sun, Haixiang; Wang, Tao; Xu, Yanyan; Li, Peng; Kong, Ying; Niu, Q. Jason

2016-01-01

Nanopore containing graphene nanosheets were synthesized by graphene oxide and a reducing agent using a facile hydrothermal treatment in sodium hydroxide media. The as-prepared nanoporous graphene was incorporated into ethyl cellulose (EC) to prepare the mixed matrix membranes (MMMs) for C3H6/C3H8 separation. Transmission electron microscopy (TEM) photograph and X-ray photoelectron spectroscopy (XPS) analysis of nanoporous graphene nanosheets indicated that the structure of nano-pore was irregular and the oxygen-containing groups in the surface were limited. More importantly, the as-prepared MMMs presented better separation performance than that of pristine EC membrane due to simultaneous enhancement of C3H6 permeability and ideal selectivity. The ideal selectivity of the MMMs with 1.125 wt‰ nanoporous graphene content for C3H6/C3H8 increased from 3.45 to 10.42 and the permeability of C3H6 increased from 57.9 Barrer to 89.95 Barrer as compared with the pristine membrane. The presumed facilitated mechanism was that the high specific surface area of nanoporous graphene in polymer matrix increased the length of the tortuous pathway formed by nanopores for the gas diffusion as compared with the pristine graphene nanosheets, and generated a rigidified interface between the EC chains and fillers, thus enhanced the diffusivity selectivity. Therefore, it is expected that nanoporous graphene would be effective material for the C3H6/C3H8 separation. PMID:27352851

Microwave assisted synthesis and anti-lipase activity of some new fluorine-containing benzimidazoles.

PubMed

Menteşe, E; Yilmaz, F; Ülker, S; Kahveci, B

2015-01-01

In this study, a new series of fluorine containing benzimidazoles (4a-l) and bisbenzimidazoles (6a-c, 8) were synthesized by the reaction of o-phenylenediamines with iminoester hydrochlorides (3a-l, 7) in methanol under microwave irradiation. The structures of these newly synthesized compounds were identified by IR, (1)H-NMR, (13)C-NMR, mass spectroscopy and elemental analysis data. The synthesized compounds were screened for their pancreatic lipase activities. Our results indicate that the compounds 6a, 6b and 6c can serve as an anti-lipase agent. The compounds 6b and 6c inhibited pancreatic lipase activity by 84.03% and 97.49% at a concentration of 3 µg/mL, respectively. © Georg Thieme Verlag KG Stuttgart · New York.

Post mortem analysis of fatigue mechanisms in LiNi0.8Co0.15Al0.05O2 - LiNi0.5Co0.2Mn0.3O2 - LiMn2O4/graphite lithium ion batteries

NASA Astrophysics Data System (ADS)

Lang, Michael; Darma, Mariyam Susana Dewi; Kleiner, Karin; Riekehr, Lars; Mereacre, Liuda; Ávila Pérez, Marta; Liebau, Verena; Ehrenberg, Helmut

2016-09-01

The fatigue of commercial lithium ion batteries after long-term cycling at two different temperatures and cycling rates is investigated. The cells are opened after cycling and post-mortem analysis are conducted. Two main contributions to the capacity loss of the batteries are revealed. The loss of active lithium leads to a relative shift between anodes and cathodes potentials. A growth of the solid electrolyte interface (SEI) on the anode is determined as well as the formation of lithium fluoride species as an electrolyte decomposition product. Those effects are reinforced by increasing cycling rates from 1C/2C (charge/discharge) to 2C/3C as well as by increasing cycling temperatures from 25 °C to 40 °C. The other contribution to the capacity loss originates from a fatigue of the blended cathodes consisting of LiNi0.5Co0.2Mn0.3O2 (NCM), LiNi0.8Co0.15Al0.05O2 (NCA) and LiMn2O4 (LMO). Phase-specific capacity losses and fatigue mechanisms are identified. The layered oxides tend to form microcracks and reveal changes of the surface structure leading to a worsening of the lithium kinetics. The cathode exhibits a loss of manganese at 40 °C cycling temperature. Cycling at 40 °C instead of 25 °C has the major impact on cathodes capacity loss, while cycling at 2C/3C rates barely influences it.

Electrical transport properties of LiNiV O ceramics

NASA Astrophysics Data System (ADS)

Ram, Moti

2009-08-01

The LiNiV O 4 fine powder has been synthesized by chemical "pyrophoric reaction process". The formation of LiNiV O 4 is confirmed by X-ray diffraction analysis. X-ray analysis shows that the compound has cubic crystal structure with lattice constant ( a=8.2243(2) Å). Microstructure of the sintered pellet is identified by taking the field emission scanning electron microscopy (FE-SEM) pictures, which reveals the grain size as ˜0.2-2 μm. Electrical properties are measured using complex impedance spectroscopy technique. Bulk contribution to electrical response is identified by the analysis of complex plane diagrams. The activation energy calculated from σ vs 10 3/T graph is ˜0.06 eV (25-225 ∘C) and ˜0.55 eV (225-375 ∘C). Complex modulus study shows non-Debye type (polydispersive) conductivity relaxation in the compound.

n-Alkane adsorption to polar silica surfaces.

PubMed

Brindza, Michael R; Ding, Feng; Fourkas, John T; Walker, Robert A

2010-03-21

The structures of medium-length n-alkane species (C(8)-C(11)) adsorbed to a hydrophilic silica/vapor interface were examined using vibrational sum frequency spectroscopy. Experiments sampling out-of-plane orientation show a clear pattern in vibrational band intensities that implies chains having primarily all-trans conformations lying flat along the interface. Further analysis shows that the methylene groups of the alkane chains have their local symmetry axes directed into and away from the surface. Spectra acquired under different polarization conditions interlock to reinforce this picture of interfacial structure and organization. Variation in signal intensities with chain length suggests that correlation between adsorbed monomers weakens with increasing chain length. This result stands in contrast with alkane behavior at neat liquid/vapor interfaces where longer length alkanes show considerably more surface induced ordering than short chain alkanes.

Acid--chlorite pretreatment and liquefaction of cornstalk in hot-compressed water for bio-oil production.

PubMed

Liu, Hua-Min; Feng, Bing; Sun, Run-Cang

2011-10-12

In this study, cornstalk was pretreated by an acid-chlorite delignification procedure to enhance the conversion of cornstalk to bio-oil in hot-compressed water liquefaction. The effects of the pretreatment conditions on the compositional and structural changes of the cornstalk and bio-oil yield were investigated. It was found that acid-chlorite pretreatment changed the main components and physical structures of cornstalk and effectively enhanced the bio-oil yield. Shorter residence time favored production of the total bio-oil products, whereas longer time led to cracking of the products. A high water loading was found to be favorable for high yields of total bio-oil and water-soluble oil. GC-MS analysis showed that the water-soluble oil and heavy oil were the complicated products of C(5-10) and C(8-11) organic compounds.

Diamond-like phases formed from fullerene-like clusters

NASA Astrophysics Data System (ADS)

Belenkov, E. A.; Greshnyakov, V. A.

2015-11-01

The geometrically optimized structure and properties of thirteen diamond-like carbon phases formed by linking or combining fullerene-like clusters (C4, C6, C8, C12, C16, C24, or C48) have been investigated. Atoms in the structures of these phases are located in crystallographically equivalent positions. The calculations have been performed using the density functional theory in the generalized gradient approximation. The calculated values of the structural characteristics and properties (sublimation energies, bulk moduli, band gaps, X-ray diffraction patterns) of the studied diamond-like phases differ significantly from the corresponding values for cubic diamond.

Structural characterization of selenium and selenium-diiodine analogues of the antithyroid drug 6-n-propyl-2-thiouracil and its alkyl derivatives.

PubMed

Antoniadis, Constantinos D; Blake, Alexander J; Hadjikakou, Sotiris K; Hadjiliadis, Nick; Hubberstey, Peter; Schröder, Martin; Wilson, Claire

2006-08-01

The structures of four selenium analogues of the antithyroid drug 6-n-propyl-2-thiouracil [systematic name: 2,3-dihydro-6-n-propyl-2-thioxopyrimidin-4(1H)-one], namely 6-methyl-2-selenouracil, C(5)H(6)N(2)OSe (1), 6-ethyl-2-selenouracil, C(6)H(8)N(2)OSe (2), 6-n-propyl-2-selenouracil, C(7)H(10)N(2)OSe (3), and 6-isopropyl-2-selenouracil, C(7)H(10)N(2)OSe (4), are described, along with that of the dichloromethane monosolvate of 6-isopropyl-2-selenouracil, C(7)H(10)N(2)OSe.CH(2)Cl(2) (4.CH(2)Cl(2)). The extended structure of (1) is a two-dimensional sheet of topology 6(3) with a brick-wall architecture. The extended structures of (2) and (4) are analogous, being based on a chain of eight-membered R(8)(6)(32) hydrogen-bonded rings. In (3) and (4.CH(2)Cl(2)), R(2)(2)(8) hydrogen bonding links molecules into chains. 6-n-Propyl-2-selenouracil.I(2), C(7)H(10)N(2)OSe.I(2) (7), is a charge-transfer complex with a ;spoke' structure, the extended structure of which is based on a linear chain formed principally by intermolecular N-H...O hydrogen bonds. Re-crystallization of 6-ethyl-2-selenouracil or (7) from acetone gave crystals of the diselenides [N-(6'-ethyl-4'-pyrimidone)(6-ethyl-2-selenouracil)(2)(Se-Se)].2H(2)O (9.2H(2)O) or [N-(6'-n-propyl-4'-pyrimidone)(6-n-propyl-2-selenouracil)(2)(Se-Se)] (10), respectively: these have similar extended chain structures formed via N-H...O and C-H...O hydrogen bonds, stacked to give two-dimensional sheets. Re-crystallization of (7) from methanol/acetonitrile led via deselenation to the formation of crystals of 6-n-propyl-2-uracil (11), in which six symmetry-related molecules combine to form a six-membered R(6)(6)(24) hydrogen-bonded ring, with each pair of molecules linked by an R(2)(2)(8) motif.

A Study of the Synchrotron Laue Method for Quantitative Crystal Structure Analysis

NASA Astrophysics Data System (ADS)

Gomez de Anderez, Dora M.

1990-01-01

Quantitative crystal structure analyses have been carried out on small molecule crystals using synchrotron radiation and the Laue method. A variety of single crystal structure determinations and associated refinements are used and compared with the monochromatic analyses. The new molecular structure of 7-amino-5-bromo -4-methyl-2-oxo-1,2,3,4 -tetrahidro-1,6 -naphthyridine-8-carbonitrile (C_{10 }H_9ON_4 BrcdotH_2O) has been determined, first using monochromatic Mo K alpha radiation and a four-circle diffractometer, then using synchrotron Laue diffraction photography. The structure refinements showed an R-factor of 4.97 and 14.0% for the Mo Kalpha and Laue data respectively. The molecular structure of (S)-2-chloro-2-fluoro-N-((S)-1-phenylethyl) ethanamide, (C_{10}H _{11}ClFNO), has been determined using the same crystal throughout for X-ray monochromatic analyses (Mo Kalpha and Cu K alpha) followed by synchrotron Laue data collection. The Laue and monochromatic data compare favourably. The R -factors (on F) were 6.23, 6.45 and 8.19% for the Mo K alpha, Cu Kalpha and Laue data sets respectively. The molecular structure of 3-(5-hydroxy-3-methyl-1-phenylpyrazol-4-yl)-1,3-diphenyl -prop-2-en-1-one, (C_{25}H _{20}N_2 O_2) has been determined using the synchrotron Laue method. The results compare very well with Mo Kalpha monochromatic data. The R-factors (on F) were 4.60 and 5.29% for Mo Kalpha and Laue analyses respectively. The Laue method is assessed in locating the 20 hydrogen atoms in this structure. The structure analyses of the benzil compound ((C_6H_5 OcdotCO_2)) is carried out using the synchrotron Laue method firstly at room temperature and secondly at low temperature. The structure shows an R-factor (on F) of 13.06% and 6.85% for each data set respectively. The synchrotron Laue method was used to collect data for ergocalciferol (Vitamin D_2). The same crystal was also used to record oscillation data with the synchrotron radiation monochromatic beam. A new molecular structure of (Dinitrato-(N,N ^'-dimethylethylene-diamine)copper(II)) has been determined using Mo Kalpha radiation on a four circle diffractometer. The refinement resulted in an R-factor (on F) of 4.06%.

Phase equilibria in the La–Mg–Ge system at 500 °C and crystal structure of the new ternary compounds La{sub 11}Mg{sub 2}Ge{sub 7} and LaMg{sub 3−x}Ge{sub 2}

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

De Negri, S., E-mail: serena.denegri@unige.it; Solokha, P.; Skrobańska, M.

2014-10-15

The whole 500 °C isothermal section of the La–Mg–Ge ternary system was constructed. The existence and crystal structure of three ternary compounds were confirmed: La{sub 2+x}Mg{sub 1−x}Ge{sub 2} (τ{sub 2}, P4/mbm, tP10–Mo{sub 2}FeB{sub 2}, 0≤x≤0.25), La{sub 4}Mg{sub 5}Ge{sub 6} (τ{sub 3}, Cmc2{sub 1}, oS60–Gd{sub 4}Zn{sub 5}Ge{sub 6}) and La{sub 4}Mg{sub 7}Ge{sub 6} (τ{sub 4}, C2/m, mS34, own structure type). Five novel compounds were identified and structurally characterized: La{sub 11}Mg{sub 2}Ge{sub 7} (τ{sub 1}, P4{sub 2}/ncm, tP88-8, own structure type, a=1.21338(5), c=1.57802(6) nm), LaMg{sub 3−x}Ge{sub 2} (τ{sub 5}, P3{sup ¯}1c, hP34-0.44, own structure type, x=0.407(5), a=0.78408(4), c=1.45257(7) nm), La{sub 6}Mg{sub 23}Gemore » (τ{sub 6}, Fm3{sup ¯}m, cF120–Zr{sub 6}Zn{sub 23}Si, a=1.46694(6) nm), La{sub 4}MgGe{sub 10−x} (τ{sub 7}, x=0.37(1), C2/m, mS60-1.46, own structure type, a=0.88403(8), b=0.86756(8), c=1.7709(2) nm, β=97.16°(1) and La{sub 2}MgGe{sub 6} (τ{sub 8}, Cmce, oS72–Ce{sub 2}(Ga{sub 0.1}Ge{sub 0.9}){sub 7}, a=0.8989(2), b=0.8517(2), c=2.1064(3) nm). Disordering phenomena were revealed in several La–Mg–Ge phases in terms of partially occupied sites. The crystal structures of La{sub 11}Mg{sub 2}Ge{sub 7} and LaMg{sub 3−x}Ge{sub 2} are discussed in details. The latter is a √3a×√3a×2c superstructure of the LaLi{sub 3}Sb{sub 2} structure type; the symmetry reduction scheme is shown in the Bärnighausen formalism terms. - Graphical abstract: La–Mg–Ge isothermal section at 500 °C and group–subgroup relation between the LaLi{sub 3}Sb{sub 2} (parent type) and LaMg{sub 3−x}Ge{sub 2} (derivative) structures. - Highlights: • Novel La−Mg−Ge compounds structure determination from X-ray single crystal data. • Disordering phenomena as common features of the studied germanides. • Bärnighausen formalism as a useful tool for accurate structure determination. • Full isothermal section of the La–Mg–Ge ternary system at 500 °C.« less

What Is the Structure of the Naphthalene-Benzene Heterodimer Radical Cation? Binding Energy, Charge Delocalization, and Unexpected Charge-Transfer Interaction in Stacked Dimer and Trimer Radical Cations.

PubMed

Attah, Isaac K; Platt, Sean P; Meot-Ner Mautner, Michael; El-Shall, M Samy; Peverati, Roberto; Head-Gordon, Martin

2015-04-02

The binding energy of the naphthalene(+•)(benzene) heterodimer cation has been determined to be 7.9 ± 1 kcal/mol for C10H8(+•)(C6H6) and 8.1 ± 1 kcal/mol for C10H8(+•)(C6D6) by equilibrium thermochemical measurements using the mass-selected drift cell technique. A second benzene molecule binds to the C10H8(+•)(C6D6) dimer with essentially the same energy (8.4 ± 1 kcal/mol), suggesting that the two benzene molecules are stacked on opposite sides of the naphthalene cation in the (C6D6)C10H8(+•)(C6D6) heterotrimer. The lowest-energy isomers of the C10H8(+•)(C6D6) and (C6D6)C10H8(+•)(C6D6) dimer and trimer calculated using the M11/cc-pVTZ method have parallel stacked structures with enthalpies of binding (-ΔH°) of 8.4 and 9.0 kcal/mol, respectively, in excellent agreement with the experimental values. The stacked face-to-face class of isomers is calculated to have substantial charge-transfer stabilization of about 45% of the total interaction energy despite the large difference between the ionization energies of benzene and naphthalene. Similarly, significant delocalization of the positive charge is found among all three fragments of the (C6D6)C10H8(+•)(C6D6) heterotrimer, thus leaving only 46% of the total charge on the central naphthalene moiety. This unexpectedly high charge-transfer component results in activating two benzene molecules in the naphthalene(+•)(benzene)2 heterotrimer cation to associate with a third benzene molecule at 219 K to form a benzene trimer cation and a neutral naphthalene molecule. The global minimum of the C10H8(+•)(C6H6)2 heterotrimer is found to be the one where the naphthalene cation is sandwiched between two benzene molecules. It is remarkable, and rather unusual, that the binding energy of the second benzene molecule is essentially the same as that of the first. This is attributed to the enhanced charge-transfer interaction in the stacked trimer radical cation.

Synthesis and characterization of two novel inorganic/organic hybrid materials based on polyoxomolybdate clusters: (C5H5N5)2(C5H6N5)4[(HAsO4)2Mo6O18]·11H2O and Na2(Himi)3[SeMo6O21(CH3COO)3]·6H2O

NASA Astrophysics Data System (ADS)

Ayed, Meriem; Mestiri, Imen; Ayed, Brahim; Haddad, Amor

2017-01-01

Two new organic-inorganic hybrid compound, (C5H5N5)2(C5H6N5)4[(HAsO4)2Mo6O18]·11H2O (I) and Na2(Himi)3[SeMo6O21(CH3COO)3]·6H2O (II) were synthesized and structurally characterized by scanning electron microscopy (SEM), elemental analyses, FTIR, UV spectroscopy, thermal stability analysis, XRD and single crystal X-ray diffraction. Crystal data: (I) triclinic system, space group P-1, a = 11,217 (9) Å, b = 11,637 (8) Å, c = 14,919 (8) Å, α = 70,90 (5)°, β = 70,83 (2)°, γ = 62,00(1)° and Z = 1; (II) triclinic system, space group P-1, a = 10.6740(1) Å, b = 10.6740(1) Å, c = 20.0570(1) Å, α = 76.285(1)°, β = 82.198(2)°, γ = 87.075(1)°, Z = 1. The crystal structure of (I) can be described by infinite polyanions [(HAsO4)2Mo6O18]4- organized with water molecules in layers parallel to the c-direction; adjacent layers are further joined up by hydrogen bonding interactions with organic groups which were associated in chains spreading along the b-direction. The structure of (II) consists of functionalized selenomolybdate clusters [SeMo6O21(CH3COO)3]5-, protonated imidazole cations, sodium ions and lattice water molecules, which are held together to generate a three-dimensional supramolecular network via hydrogen-bonding interaction. Furthermore, the electrochemical properties of these compounds have been studied.

Backbone amide 15N chemical shift tensors report on hydrogen bonding interactions in proteins: A magic angle spinning NMR study.

PubMed

Paramasivam, Sivakumar; Gronenborn, Angela M; Polenova, Tatyana

2018-08-01

Chemical shift tensors (CSTs) are an exquisite probe of local geometric and electronic structure. 15 N CST are very sensitive to hydrogen bonding, yet they have been reported for very few proteins to date. Here we present experimental results and statistical analysis of backbone amide 15 N CSTs for 100 residues of four proteins, two E. coli thioredoxin reassemblies (1-73-(U- 13 C, 15 N)/74-108-(U- 15 N) and 1-73-(U- 15 N)/74-108-(U- 13 C, 15 N)), dynein light chain 8 LC8, and CAP-Gly domain of the mammalian dynactin. The 15 N CSTs were measured by a symmetry-based CSA recoupling method, ROCSA. Our results show that the principal component δ 11 is very sensitive to the presence of hydrogen bonding interactions due to its unique orientation in the molecular frame. The downfield chemical shift change of backbone amide nitrogen nuclei with increasing hydrogen bond strength is manifested in the negative correlation of the principal components with hydrogen bond distance for both α-helical and β-sheet secondary structure elements. Our findings highlight the potential for the use of 15 N CSTs in protein structure refinement. Copyright © 2018 Elsevier Inc. All rights reserved.

Synthesis, characterization, crystal structure and theoretical studies of 4-[(E)-(3-chloro-4-hydroxyphenyl) diazenyl]-1, 5-dimethyl-2-phenyl-1, 2-dihydro-3H-pyrazol-3-one

NASA Astrophysics Data System (ADS)

Athira, L. S.; Lakshmi, C. S. Nair; Balachandran, S.; Arul Dhas, D.; Hubert Joe, I.

2017-11-01

Crystals of new heterocyclic azo compound of 4-aminoantipyrine, 4-[(E)-(3-chloro-4-hydroxyphenyl)diazenyl]-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one have been grown by slow evaporation method at room temperature and its structural characterization was performed by X- ray diffraction method. The spectroscopic characterization was also performed by FT-IR, UV-Vis, 13C and 1H NMR techniques. The compound crystallizes in the monoclinic CC space group with cell dimensions a = 12.4842 (13), b = 16.4492 (16), c = 8.3389 (8) and β = 102.698 (3)°. The phenyl ring attached to the pyrazolone moiety is disordered over two positions with an occupancy ratio 52:48. The components of the disorder were refined. DFT calculations have been performed by using B3LYP/6-311G (d,p) level basis set. The calculated vibrational frequency showed a red shift for Cdbnd O and OH stretching. The natural bond orbital analysis of monomer, dimer and trimer structures reveals the absence of intramolecular hydrogen bonding; however intermolecular hydrogen bonding is observed. The cationic and anionic reactive sites of compound have been visualized on MEP surface.

Three-Dimensional Networks of S-Doped Fe/N/C with Hierarchical Porosity for Efficient Oxygen Reduction in Polymer Electrolyte Membrane Fuel Cells.

PubMed

Wu, Yi-Jin; Wang, Yu-Cheng; Wang, Rui-Xiang; Zhang, Peng-Fang; Yang, Xiao-Dong; Yang, Hui-Juan; Li, Jun-Tao; Zhou, Yao; Zhou, Zhi-You; Sun, Shi-Gang

2018-05-02

Reasonable design and synthesis of Fe/N/C-based catalysts is one of the most promising way for developing precious metal-free oxygen reduction reaction (ORR) catalysts in acidic mediums. Herein, we developed a highly active metal-organic framework-derived S-doped Fe/N/C catalyst [S-Fe/Z8/2-aminothiazole (2-AT)] prepared by thermal treatment. The S-Fe/Z8/2-AT catalyst with uniform S-doping possesses a three-dimensional macro-meso-micro hierarchically porous structure. Moreover, the chemical composition and structural features have been well-optimized and characterized for such S-Fe/Z8/2-AT catalysts; and their formation mechanism was also revealed. Significantly, applying the optimal S-Fe/Z8/2-AT catalysts into electrocatalytic test exhibits remarkable ORR catalytic activity with a half-wave potential of 0.82 V (vs reversible hydrogen electrode) and a mass activity of 18.3 A g -1 at 0.8 V in 0.1 M H 2 SO 4 solution; the polymer electrolyte membrane fuel cell test also confirmed their excellent catalytic activity, which gives a maximal power density as high as 800 mW cm -2 at 1 bar. A series of designed experiments disclosed that the favorable structural merits and desirable chemical compositions of S-Fe/Z8/2-AT catalysts are critical factors for efficient electrocatalytic performance. The work provides a new approach to open an avenue for accurately controlling the composition and structure of Fe/N/C catalysts with highly activity for ORR.

Experimental and computational studies on creatininium 4-nitrobenzoate - An organic proton transfer complex

NASA Astrophysics Data System (ADS)

Thirumurugan, R.; Anitha, K.

2017-10-01

A new organic proton transfer complex of creatininium 4-nitrobenzoate (C4NB) has been synthesized and its single crystals were grown successfully by slow evaporation technique. The grown single crystal was subjected to various characterization techniques like single crystal X-ray diffraction (SCXRD), FTIR, FT-Raman and Kurtz-Perry powder second harmonic generation (SHG). The SCXRD analysis revealed that C4NB was crystallized into orthorhombic crystal system, with noncentrosymmetric (NCS), P212121 space group. The creatininium cation and 4-nitrobenzoate anion were connected through a pair of N__H⋯O hydrogen bonds (N(3)__H(6) ⋯ O(3) (x+1, y, z) and N(2)__H(5) &ctdot O(2) (x-1/2, -y-1/2, -z+2)) and fashioned a R22(8) ring motif. The crystal structure was stabilized by strong N__H⋯O and weak C__H⋯O intermolecular interactions and it was quantitatively analysed by Hirshfeld surface and fingerprint (FP) analysis. FTIR and FT-Raman studies confirmed the vibrational modes of functional groups present in C4NB compound indubitably. SHG efficiency of grown crystal was 4.6 times greater than that of standard potassium dihydrogen phosphate (KDP) material. Moreover, density functional theory (DFT) studies such as Mulliken charge distribution, frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) map, natural bond orbital analysis (NBO) and first order hyperpolarizability (β0) were calculated to explore the structure-property relationship.

Separation and purification of triterpene saponins from roots of Radix phytolaccae by high-speed countercurrent chromatography coupled with evaporative light scattering detection

PubMed Central

Ma, Jie; Chen, Qianliang; Lai, Daowan; Sun, Wenji; Zhang, Tianyou; Ito, Yoichiro

2009-01-01

Coupled with evaporative light scattering detection, high-speed countercurrent chromatography was successfully applied for the first time to separation and purification of four triterpene saponins including esculentoside A, B, C and D from roots of Radix Phytolaccae. The separation was performed with an optimized two-phase solvent system composed of chloroform-methanol-water (4:4:2, v/v) using the lower phase as the mobile phase at a flow rate of 1.5 ml/min,. From 150 mg of crude extract 46.3 mg of esculentoside A, 21.8 mg of esculentoside B, 7.3 mg of esculentoside C, and 13.6 mg of esculentoside D were obtained at purities of 96.7%, 99.2%, 96.5% and 97.8%, respectively, as determined by HPLC analysis. The structures of the four triterpene saponins were identified by ESI-MS,1H NMR and 13C NMR. PMID:20454595

Supramolecular interactions in carboxylate and sulfonate salts of 2,6-diamino-4-chloropyrimidinium.

PubMed

Mohana, Marimuthu; Thomas Muthiah, Packianathan; Butcher, Ray J

2017-07-01

Two new salts, namely 2,6-diamino-4-chloropyrimidinium 2-carboxy-3-nitrobenzoate, C 4 H 6 ClN 4 + ·C 8 H 4 NO 6 - , (I), and 2,6-diamino-4-chloropyrimidinium p-toluenesulfonate monohydrate, C 4 H 6 ClN 4 + ·C 7 H 7 O 3 S - ·H 2 O, (II), have been synthesized and characterized by single-crystal X-ray diffraction. In both crystal structures, the N atom in the 1-position of the pyrimidine ring is protonated. In salt (I), the protonated N atom and the amino group of the pyrimidinium cation interact with the carboxylate group of the anion through N-H...O hydrogen bonds to form a heterosynthon with an R 2 2 (8) ring motif. In hydrated salt (II), the presence of the water molecule prevents the formation of the familiar R 2 2 (8) ring motif. Instead, an expanded ring [i.e. R 3 2 (8)] is formed involving the sulfonate group, the pyrimidinium cation and the water molecule. Both salts form a supramolecular homosynthon [R 2 2 (8) ring motif] through N-H...N hydrogen bonds. The molecular structures are further stabilized by π-π stacking, and C=O...π, C-H...O and C-H...Cl interactions.

Cytotoxic Flavones from the Stem Bark of Bougainvillea spectabilis Willd.

PubMed

Do, Lien T M; Aree, Thammarat; Siripong, Pongpun; Vo, Nga T; Nguyen, Tuyet T A; Nguyen, Phung K P; Tip-Pyang, Santi

2018-01-01

Five new flavones possessing a fully substituted A-ring with C-6 and C-8 methyl groups, bougainvinones I - M (1: -5: ), along with three known congeners, 2'-hydroxydemethoxymatteucinol (6: ), 5,7,3',4'-tetrahydroxy-3-methoxy-6,8-dimethylflavone (7: ) and 5,7,4'-trihydroxy-3-methoxy-6,8-dimethylflavone (8: ), were isolated from the EtOAc extract of the stem bark of Bougainvillea spectabilis . Their structures were established by means of spectroscopic data (ultraviolet, infrared, high-resolution electrospray ionization mass spectrometry, and one-dimensional and two-dimensional nuclear magnetic resonance) and single-crystal X-ray crystallographic analysis. The in vitro cytotoxicity of all isolated compounds against five cancer cell lines (KB, HeLa S-3, MCF-7, HT-29, and HepG2) was evaluated. Compound 5: showed promising cytotoxic activity against the KB and HeLa S-3 cell lines, with IC 50 values of 7.44 and 6.68 µM. The other compounds exhibited moderate cytotoxicity against the KB cell line. Georg Thieme Verlag KG Stuttgart · New York.

Computational and Experimental Characterization of Five Crystal Forms of Thymine: Packing Polymorphism, Polytypism/Disorder and Stoichiometric 0.8-Hydrate.

PubMed

Braun, Doris E; Gelbrich, Thomas; Wurst, Klaus; Griesser, Ulrich J

2016-06-01

New polymorphs of thymine emerged in an experimental search for solid forms, which was guided by the computationally generated crystal energy landscape. Three of the four anhydrates (AH) are homeoenergetic ( A° - C ) and their packing modes differ only in the location of oxygen and hydrogen atoms. AHs A° and B are ordered phases, whereas AH C shows disorder (X-ray diffuse scattering). Anhydrates AHs A° and B are ordered phases, whereas AH C shows disorder (X-ray diffuse scattering). Analysis of the crystal energy landscape for alternative AH C hydrogen bonded ribbon motifs identified a number of different packing modes, whose 3D structures were calculated to deviate by less than 0.24 kJ mol -1 in lattice energy. These structures provide models for stacking faults. The three anhydrates A ° - C show strong similarity in their powder X-ray diffraction, thermoanalytical and spectroscopic (IR and Raman) characteristics. The already known anhydrate AH A ° was identified as the thermodynamically most stable form at ambient conditions; AH B and AH C are metastable but show high kinetic stability. The hydrate of thymine is stable only at water activities ( a w ) > 0.95 at temperatures ≤ 25 °C. It was found to be a stoichiometric hydrate despite being a channel hydrate with an unusual water:thymine ratio of 0.8:1. Depending on the dehydration conditions, either AH C or AH D is obtained. The hydrate is the only known precursor to AH D . This study highlights the value and complementarity of simultaneous explorations of computationally and experimentally generated solid form landscapes of a small molecule anhydrate ↔ hydrate system.

Computational and Experimental Characterization of Five Crystal Forms of Thymine: Packing Polymorphism, Polytypism/Disorder and Stoichiometric 0.8-Hydrate

PubMed Central

Braun, Doris E.; Gelbrich, Thomas; Wurst, Klaus; Griesser, Ulrich J.

2017-01-01

New polymorphs of thymine emerged in an experimental search for solid forms, which was guided by the computationally generated crystal energy landscape. Three of the four anhydrates (AH) are homeoenergetic (A° – C) and their packing modes differ only in the location of oxygen and hydrogen atoms. AHs A° and B are ordered phases, whereas AH C shows disorder (X-ray diffuse scattering). Anhydrates AHs A° and B are ordered phases, whereas AH C shows disorder (X-ray diffuse scattering). Analysis of the crystal energy landscape for alternative AH C hydrogen bonded ribbon motifs identified a number of different packing modes, whose 3D structures were calculated to deviate by less than 0.24 kJ mol–1 in lattice energy. These structures provide models for stacking faults. The three anhydrates A° – C show strong similarity in their powder X-ray diffraction, thermoanalytical and spectroscopic (IR and Raman) characteristics. The already known anhydrate AH A° was identified as the thermodynamically most stable form at ambient conditions; AH B and AH C are metastable but show high kinetic stability. The hydrate of thymine is stable only at water activities (aw) > 0.95 at temperatures ≤ 25 °C. It was found to be a stoichiometric hydrate despite being a channel hydrate with an unusual water:thymine ratio of 0.8:1. Depending on the dehydration conditions, either AH C or AH D is obtained. The hydrate is the only known precursor to AH D. This study highlights the value and complementarity of simultaneous explorations of computationally and experimentally generated solid form landscapes of a small molecule anhydrate ↔ hydrate system. PMID:28663717

Novel red phosphors KBaEu(XO4)3 (X = Mo, W) show high color purity and high thermostability from a disordered chained structure.

PubMed

Wang, G Q; Gong, X H; Chen, Y J; Huang, J H; Lin, Y F; Luo, Z D; Huang, Y D

2017-05-23

Two novel red phosphors KBaEu(XO 4 ) 3 (X = Mo, W) have been synthesized by high-temperature solid-state reactions and the crystal structures were determined for the first time. Single-crystal X-ray diffraction data reveal that their space groups are C2/c. The crystalline structure is constituted of K/BaO 8 distorted square antiprisms and distorted EuO 8 polyhedra which form chains lying along the c-axis and two kinds of distorted XO 4 tetrahedra. This high disorder of K/Ba which might lower the crystal field symmetry around Eu 3+ results in the high purity of red emission around 615 nm originating from 5 D 0 → 7 F 2 transition under near-ultraviolet (NUV) excitation. With increasing temperature, the luminescence of KBaEu(XO 4 ) 3 (X = Mo, W) phosphors decreases almost linearly with subtle alteration for the CIE coordinate. As the temperature reaches 550 K, the red emission intensity decreases to 37.3% and 50.7% of that at 300 K for KBaEu(MoO 4 ) 3 and KBaEu(WO 4 ) 3 , respectively. The analysis of the decay curves of the 5 D 0 → 7 F 2 emission at variable temperatures indicates the weak cross relaxation and non-radiative energy transfer between Eu 3+ ions. These results demonstrate that the investigated phosphors are attractive for application in high power NUV excited white LEDs.

Accurate gas-phase structure of para-dioxane by fs Raman rotational coherence spectroscopy and ab initio calculations

NASA Astrophysics Data System (ADS)

Den, Takuya; Menzi, Samuel; Frey, Hans-Martin; Leutwyler, Samuel

2017-08-01

p-Dioxane is non-polar, hence its rotational constants cannot be determined by microwave rotational coherence spectroscopy (RCS). We perform high-resolution gas-phase rotational spectroscopy of para-dioxane-h8 and -d8 using femtosecond time-resolved Raman RCS in a gas cell at T = 293 K and in a pulsed supersonic jet at T ˜130 K. The inertial tensor of p-dioxane-h8 is strongly asymmetric, leading to a large number of asymmetry transients in its RCS spectrum. In contrast, the d8-isotopomer is a near-oblate symmetric top that exhibits a much more regular RCS spectrum with few asymmetry transients. Fitting the fs Raman RCS transients of p-dioxane-h8 to an asymmetric-top model yields the ground-state rotational constants A0 = 5084.4(5) MHz, B0 = 4684(1) MHz, C0 = 2744.7(8) MHz, and (A0 + B0)/2 = 4884.5(7) MHz (±1 σ ). The analogous values for p-dioxane-d8 are A0 = 4083(2) MHz, B0 = 3925(4) MHz, C0 = 2347.1(6) MHz, and (A0 + B0)/2 = 4002.4(6) MHz. We determine the molecular structure with a semi-experimental approach involving the highly correlated coupled-cluster singles, doubles and iterated triples method and the cc-pCVXZ basis set series from double- to quadruple-zeta (X = D, T, Q). Combining the calculated vibrationally averaged rotational constants A0c a l c(X ) ,B0c a l c(X ) ,C0c a l c(X ) for increasing basis-set size X with non-linear extrapolation to the experimental constants A0e x p,B0e x p,C0e x p allows to determine the equilibrium ground state structure of p-dioxane. For instance, the equilibrium C-C and C-O bond lengths are re(CC) = 1.5135(3) Å and re(CO) = 1.4168(4) Å, and the four axial C-H bond lengths are 0.008 Å longer than the four equatorial ones. The latter is ascribed to the trans-effect (anomeric effect), i.e., the partial delocalization of the electron lone-pairs on the O atoms that are oriented trans, relative to the axial CH bonds.

Development of Microsatellite Markers and Analysis of Genetic Diversity and Population Structure of Colletotrichum gloeosporioides from Ethiopia

PubMed Central

Moges, Asmare D.; Admassu, Belayneh; Belew, Derbew; Yesuf, Mohammed; Njuguna, Joyce; Kyalo, Martina; Ghimire, Sita R.

2016-01-01

Twenty three polymorphic microsatellite markers were developed for citrus plant pathogenic fungus, Colletotrichum gloeosporioides, and were used to analyze genetic diversity and population structure of 163 isolates from four different geographical regions of Ethiopia. These loci produced a total of 118 alleles with an average of 5.13 alleles per microsatellite marker. The polymorphic information content values ranged from 0.104 to 0.597 with an average of 0.371. The average observed heterozygosity across all loci varied from 0.046 to 0.058. The gene diversity among the loci ranged from 0.106 to 0.664. Unweighted Neighbor-joining and population structure analysis grouped these 163 isolates into three major groups. The clusters were not according to the geographic origin of the isolates. Analysis of molecular variance showed 85% of the total variation within populations and only 5% among populations. There was low genetic differentiation in the total populations (FST = 0.049) as evidenced by high level of gene flow estimate (Nm = 4.8 per generation) among populations. The results show that Ethiopian C. gloeosporioides populations are generally characterized by a low level of genetic diversity. The newly developed microsatellite markers were useful in analyzing the genetic diversity and population structure of the C. gloeosporioides populations. Information obtained from this study could be useful as a base to design strategies for better management of leaf and fruit spot disease of citrus in Ethiopia. PMID:26978654

X-ray structural studies and physicochemical characterization of (E)-6-(3,4-dimethoxyphenyl)-1-ethyl-4-mesitylimino-3-methyl- 3,4-dihydro-2(1H)-pyrimidinone polymorphs.

PubMed

Miyamae, A; Kitamura, S; Tada, T; Koda, S; Yasuda, T

1991-10-01

The polymorphism of (E)-6-(3,4-dimethoxyphenyl)-1-ethyl-4-mesitylimino-3-methyl-3,4-di hydro- 2(1 H)-pyrimidinone (FK664; 1) was characterized by using X-ray powder diffractometry, differential scanning calorimetry (DSC), and IR spectroscopy. Structures of two polymorphs (Forms A and B) were determined by X-ray crystallographic analysis. Form A crystallized in the monoclinic space group P2(1)/c, with a = 13.504(2), b = 6.733(1), c = 24.910(8) A, beta = 96.55(4) degrees, z = 4, and dcal = 1.203 g/cm3, while Form B crystallized in the same space group, with a = 8.067(2), b = 15.128(4), c = 18.657(4) A, beta = 102.34(3) degrees, z = 4, and dcal = 1.216 g/cm3. The conformational features of 1 were very similar between the two polymorphs. Compound 1, in both crystal forms, took an energetically reasonable conformation in three rigid planes, such as 2-pyrimidone, trimethylphenyl, and dimethoxyphenyl rings, but the molecules were packed in different ways between the two polymorphs. In the Form B crystal, a short contact was possible, to form pi-pi interactions between two dimethoxyphenyl groups related with the inversion center in the crystal lattice; this interaction seems to contribute to stabilizing the crystal structure of Form B. Both Forms A and B showed only one endothermic peak due to fusion at 115 and 140 degrees C, respectively, on the DSC thermograms; therefore, it is suggested that there are no transition points between the two polymorphs. The heats of fusion obtained from the DSC thermograms were 33.2(2) kJ/mol for Form A and 36.8(1) kJ/mol for Form B.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for major input of riverine organic matter into the ocean

USGS Publications Warehouse

Cao, Xiaoyan; Aiken, George R.; Butler, Kenna D.; Huntington, Thomas G.; Balch, William M.; Mao, Jingdong; Schmidt-Rohr, Klaus

2018-01-01

The changes in the structure of XAD-8 isolated dissolved organic matter (DOM) samples along a river (Penobscot River) to estuary (Penobscot Bay) to ocean (across the Gulf of Maine) transect and from the Pacific Ocean were investigated using selective and two dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy coupled with elemental and carbon isotope analysis. The results provide important insights into the nature of relatively stable structures in the river-to-ocean continuum and the enigma of the fate of terrestrial DOM in the marine system. First, lignin and carboxyl-rich alicyclic molecules (CRAMs), which are indistinguishable from mass spectrometry, were clearly differentiated with NMR spectroscopy. NMR unambiguously showed that CRAMs persisted along the river-to-ocean transect and in the Pacific Ocean, while lignin residues dramatically decreased in abundance from the river to the coastal ocean and the Pacific Ocean. The results challenge a previous conclusion that lignin-derived compounds are refractory and can accumulate in the coastal ocean. The loss of terrestrial plant-derived aromatic compounds such as lignin and tannin residues throughout the sequence of riverine, coastal, and open ocean DOM extracts could also partially explain the decreasing organic carbon recovery by XAD-8 isolation and the change in carbon stable isotope composition from riverine DOM (δ13C −27.6‰) to ocean DOM (δ13C −23.0‰) extracts. The observation, from advanced NMR, of similar CRAM molecules in XAD-8 isolated DOM samples from the Penobscot River to the Penobscot Bay and from the ocean refutes a previous conclusion that XAD-isolated DOM samples from seawater and river are distinctly different. The alicyclic structural features of CRAMs and their presence as the major structural units in DOM extracts from the Penobscot River to Gulf of Maine transect, together with the deduced old 14C age of CRAMs in the ocean, imply that terrestrial CRAMs may persist on timescales long enough to be transported into the ocean.

The box C/D sRNP dimeric architecture is conserved across domain Archaea

PubMed Central

Bower-Phipps, Kathleen R.; Taylor, David W.; Wang, Hong-Wei; Baserga, Susan J.

2012-01-01

Box C/D small (nucleolar) ribonucleoproteins [s(no)RNPs] catalyze RNA-guided 2′-O-ribose methylation in two of the three domains of life. Recent structural studies have led to a controversy over whether box C/D sRNPs functionally assemble as monomeric or dimeric macromolecules. The archaeal box C/D sRNP from Methanococcus jannaschii (Mj) has been shown by glycerol gradient sedimentation, gel filtration chromatography, native gel analysis, and single-particle electron microscopy (EM) to adopt a di-sRNP architecture, containing four copies of each box C/D core protein and two copies of the Mj sR8 sRNA. Subsequently, investigators used a two-stranded artificial guide sRNA, CD45, to assemble a box C/D sRNP from Sulfolobus solfataricus with a short RNA methylation substrate, yielding a crystal structure of a mono-sRNP. To more closely examine box C/D sRNP architecture, we investigate the role of the omnipresent sRNA loop as a structural determinant of sRNP assembly. We show through sRNA mutagenesis, native gel electrophoresis, and single-particle EM that a di-sRNP is the near exclusive architecture obtained when reconstituting box C/D sRNPs with natural or artificial sRNAs containing an internal loop. Our results span three distantly related archaeal species—Sulfolobus solfataricus, Pyrococcus abyssi, and Archaeoglobus fulgidus—indicating that the di-sRNP architecture is broadly conserved across the entire archaeal domain. PMID:22753779

The box C/D sRNP dimeric architecture is conserved across domain Archaea.

PubMed

Bower-Phipps, Kathleen R; Taylor, David W; Wang, Hong-Wei; Baserga, Susan J

2012-08-01

Box C/D small (nucleolar) ribonucleoproteins [s(no)RNPs] catalyze RNA-guided 2'-O-ribose methylation in two of the three domains of life. Recent structural studies have led to a controversy over whether box C/D sRNPs functionally assemble as monomeric or dimeric macromolecules. The archaeal box C/D sRNP from Methanococcus jannaschii (Mj) has been shown by glycerol gradient sedimentation, gel filtration chromatography, native gel analysis, and single-particle electron microscopy (EM) to adopt a di-sRNP architecture, containing four copies of each box C/D core protein and two copies of the Mj sR8 sRNA. Subsequently, investigators used a two-stranded artificial guide sRNA, CD45, to assemble a box C/D sRNP from Sulfolobus solfataricus with a short RNA methylation substrate, yielding a crystal structure of a mono-sRNP. To more closely examine box C/D sRNP architecture, we investigate the role of the omnipresent sRNA loop as a structural determinant of sRNP assembly. We show through sRNA mutagenesis, native gel electrophoresis, and single-particle EM that a di-sRNP is the near exclusive architecture obtained when reconstituting box C/D sRNPs with natural or artificial sRNAs containing an internal loop. Our results span three distantly related archaeal species--Sulfolobus solfataricus, Pyrococcus abyssi, and Archaeoglobus fulgidus--indicating that the di-sRNP architecture is broadly conserved across the entire archaeal domain.

Synthesis, crystal structure and characterization of a new organic-inorganic hybrid material 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate

NASA Astrophysics Data System (ADS)

Lassoued, Mohamed Saber; Abdelbaky, Mohammed S. M.; Lassoued, Abdelmajid; Ammar, Salah; Gadri, Abdellatif; Ben Salah, Abdelhamid; García-Granda, Santiago

2018-03-01

The present paper undertakes the study of (C6H16N2) SnCl6·3H2O which is a new hybrid compound. It was prepared and characterized by single crystal X-ray diffraction, X-ray powder, Hirshfeld surface, Spectroscopy measurement, thermal study and photoluminescence properties. The single crystal X-ray diffraction studies revealed that the compound crystallizes in monoclinic Cc space group with cell parameters a = 8.3309(9) Å, b = 22.956(2) Å, c = 9.8381(9) Å, β = 101.334(9) ° and Z = 4. The atomic arrangement shows an alternation of organic and inorganic entities. The cohesion between these entities is performed via Nsbnd H⋯Cl, Nsbnd H⋯O, Osbnd H⋯Cl and Osbnd H⋯O hydrogen bonding to form a three-dimensional network. Hirshfeld surface analysis was used to investigate intermolecular interactions, as well 2D finger plots were conducted to reveal the contribution of these interactions in the crystal structure quantitatively. The X-ray powder is in agreement with the X-ray structure. Scanning electron microscope (SEM) was carried out. Furthermore, the room temperature infrared (IR) spectrum of the title compound was recorded and analyzed on the basis of data found in the literature. Solid state 13C NMR spectrum shows four signals, confirming the solid state structure determined by X-ray diffraction. Besides, the thermal analysis studies were performed, but no phase transition was found in the temperature range between 30 and 450 °C. The optical and PL properties of the compound were investigated in the solid state at room temperature and exhibited three bands at 348 and 401 cm-1 and a strong fluorescence at 480 nm.

Survey of Army/NASA Rotorcraft Aeroelastic Stability Research

DTIC Science & Technology

1988-10-01

modal analysis of aeroelastic sLaoili:v of .niform 5ant:- lever rotor blades that clearlv .llustra:ea the significar: ;.fl- ence : :ne -cn - ear bending... ence 8, the Newtonian approach does, not necessarily yield a syMetriC structural operator and althort3. the equations from the two methods are not... ence 69 to a true finite-element form so that the generalized coorainates were actual displacements and slopes at ends of the element. In addition to the

Transition metal coordination polymers based on tetrabromoterephthalic and bis(imidazole) ligands: Syntheses, structures, topological analysis and photoluminescence properties

NASA Astrophysics Data System (ADS)

Zhang, Xiaowei; Xing, Peiqi; Geng, Xiujuan; Sun, Daofeng; Xiao, Zhenyu; Wang, Lei

2015-09-01

Eight new coordination polymers (CPs), namely, [Zn(1,2-mbix)(tbtpa)]n (1), [Co(1,2-mbix)(tbtpa)]n (2), [CdCl(1,2-mbix)(tbtpa)0.5]n (3), {[Cd(1,2-bix)(tbtpa)]·H2O}n (4), {[Cd0.5(1,2-bix)(tbtpa)0.5]·H2O}n (5), {[Co0.5(1,2-bix)(tbtpa)0.5]·2H2O}n (6), {[Co(1,2-bix)(tbtpa)]·H2O}n (7) and {[Co(1,2-bix)(tbtpa)]·Diox·2H2O}n (8), were synthesized under solvothermal conditions based on mix-ligand strategy (H2tbtpa=tetrabromoterephthalic acid and 1,2-mbix=1,2-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, 1,2-bix=1,2-bis(imidazol-1-ylmethyl)benzene). All of the CPs have been structurally characterized by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). X-ray diffraction analyses show that 1 and 2 are isotypics which have 2D highly undulated networks with (4,4)-sql topology with the existence of C-H ⋯Br interactions; for 3, it has a 2D planar network with (4,4)-sql topology with the occurrence of C-H ⋯Cl interactions other than C-H ⋯Br interactions; 4 shows a 3D 2-fold interpenetrated nets with rare 65·8-mok topology which has a self-catention property. As the same case as 1 and 2, 5 and 6 are also isostructural with planar layers with 44-sql topology which further assembled into 3D supramolecular structure through the interdigitated stacking fashion and the C-Br ⋯Cph interactions. As for 7, it has a 2D slightly undulated networks with (4,4)-sql topology which has one dimension channel. While 8 has a 2-fold interpenetrated networks with (3,4)-connect jeb topology with point symbol {63}{65·8}. And their structures can be tuned by conformations of bis(imidazol) ligands and solvent mixture. Besides, the TGA properties for all compounds and the luminescent properties for 1, 3, 4, 5 are discussed in detail.

Crystal structures and transition mechanism of VO{sub 2}(A)

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

Oka, Yoshio; Yao, Takeshi; Yamamoto, Naoichi

1998-12-01

Structures of VO{sub 2}(A) have been redetermined by single-crystal diffractometry for low- (LTP) and high-temperature (HTP) phases at 298 and 473 K, respectively. The LTP adopts the tetragonal system P4/ncc with a = 8.4403(9) {angstrom}, c = 7.666(1) {angstrom}, and Z = 16, whereas the HTP adopts the body-centered tetragonal system I4/m with a = 8.476(2) {angstrom}, c = 3.824(2) {angstrom}, and Z = 8. The refinements led to R/R{sub w} = 0.031/0.032 for LTP and 0.012/0.033 for HTP. The structures of both phases consist of edge-sharing VO{sub 6} octahedra and exhibit quite similar oxygen frameworks. Through the transition themore » V{sup 4+}-V{sup 4+} bonding in LTP with a distance of 2.7695(8) {angstrom} is dissociated in HTP to a distance of 3.0794(3) {angstrom}. The transition occurs with cooperative movements of the V atoms, namely, a rotation around the c axis and a shift along the c axis. Strangely, twinning is induced on the LTP to HTP transition but disappears on the reverse transition.« less

Crystal structures of fac-tri-carbonyl-chlorido-(6,6'-dihy-droxy-2,2'-bi-pyridine)-rhenium(I) tetra-hydro-furan monosolvate and fac-bromido-tricarbon-yl(6,6'-dihy-droxy-2,2'-bi-pyridine)-manganese(I) tetra-hydro-furan monosolvate.

PubMed

Lense, Sheri; Piro, Nicholas A; Kassel, Scott W; Wildish, Andrew; Jeffery, Brent

2016-08-01

The structures of two facially coordinated Group VII metal complexes, fac-[ReCl(C10H8N2O2)(CO)3]·C4H8O (I·THF) and fac-[MnBr(C10H8N2O2)(CO)3]·C4H8O (II·THF), are reported. In both complexes, the metal ion is coordinated by three carbonyl ligands, a halide ligand, and a 6,6'-dihy-droxy-2,2'-bi-pyridine ligand in a distorted octa-hedral geometry. Both complexes co-crystallize with a non-coordinating tetra-hydro-furan (THF) solvent mol-ecule and exhibit inter-molecular but not intra-molecular hydrogen bonding. In both crystal structures, chains of complexes are formed due to inter-molecular hydrogen bonding between a hy-droxy group from the 6,6'-dihy-droxy-2,2'-bi-pyridine ligand and the halide ligand from a neighboring complex. The THF mol-ecule is hydrogen bonded to the remaining hy-droxy group.

Diastereoselective synthesis of ethyl ( Z)-3-(8-methylimidazo-[1,2- a]pyrid-2-yl)-2-phenylthioacrylate. X-ray crystal structure and conformational analysis

NASA Astrophysics Data System (ADS)

Gautier, A.; Roche, D.; Métin, J.; Carpy, A.; Madesclaire, M.

1995-09-01

The title compound 2, a gem vinyl sulfide ester, has been obtained diastereoselectively (de > 98%) by action of the ethyl thiophenoxyacetate carbanion on the imidazo[1,2- a]pyridinecarbaldehyde 1 in a basic medium, at low temperature. The X-ray crystal structure of 2 (C 19H 19N 2O 2S: Mr = 338.43, triclinic, P 1¯, a = 8.193(3) Å, b = 10.090(2) Å, c = 10.981(4) Å, α = 88.12(2)°, β = 78.66(4)°, γ = 78.53(2)°, V = 872.3(6) Å3, Z = 2, Dcalc = 1.29 g cm -3, λ( Mo Kα) = 0.71069 Å, μ = 0.189 mm -1, F(000) = 356, T = 293 K, R = 0.043 for 3610 observed reflections) has been determined and confirmed the Z configuration. The molecule is almost planar except for the phenyl ring situated in an approximate perpendicular plane. Despite the presence of the conjugate double bonds of the vinyl ester group (acrylate), coplanar with the imidazopyridine heterocycle, there is no evidence of π-electron delocalization over the whole structure. The crystal cohesion is ensured by a dense network of van der Waals contacts. A conformational analysis of the Z and E isomers by means of a Monte Carlo search and a stochastic dynamics simulation in CHCl 3 has shown that according to the method the Z isomer is more stable than the E isomer by about 7 to 10 kJ mol -1.

Molecular characterization and expression analysis of the myostatin gene and its association with growth traits in Noble scallop (Chlamys nobilis).

PubMed

Fan, Sigang; Xu, Youhou; Liu, Baosuo; He, Wenyao; Zhang, Bo; Su, Jiaqi; Yu, Dahui

2017-10-01

Myostatin (MSTN), also called growth and differentiation factor-8 (GDF-8), is a member of the transforming growth factor-β (TGF-β) superfamily and an inhibitor of muscle differentiation and growth. In this report, we identified and characterized a MSTN gene (CnMSTN) from the scallop Chlamys nobilis. The open reading frame of CnMSTN was 1374bp in length, encoding 457 amino acids. The structure of CnMSTN included a putative signal peptide, a TGF-β propeptide domain, and a conserved TGF-β domain. Phylogenetic analysis showed that the CnMSTN gene was clustered in the same subgroup with the MSTN gene found in Mollusca. Quantitative real-time PCR showed that the CnMSTN gene was widely expressed in all tissues tested, with the highest expression level observed in the adductor muscle. Six single nucleotide polymorphisms (SNPs) were identified in the promoter region, but no SNP was detected in the exon regions. Association analysis showed that SNP g.-579A/C had significant effects on body mass, soft-tissue mass, and adductor muscle mass. The CC and AC genotypes of g.-579A/C had significantly higher growth trait values than that of genotype AA (P<0.05). These results suggest that CnMSTN could be used as a candidate gene for the selective breeding of C. nobilis. Copyright © 2017 Elsevier Inc. All rights reserved.

Insight towards the conserved water mediated recognition of catalytic and structural Zn(+2) ions in human Matrix Metalloproteinase-8 enzyme: A study by MD-simulation methods.

PubMed

Chakrabarti, Bornali; Bairagya, Hridoy R; Mishra, Deepak Kr; Chatterjee, Pradip Kumar; Mukhopadhyay, Bishnu P

2013-01-01

Human matrix metalloproteinase-8 (hMMP-8) plays a important role in the progression of colorectal cancer, metastasis, multiple sclerosis and rheumetoid arthritis. Extensive MD-simulation of the PDB and solvated structures of hMMP-8 has revealed the presence of few conserved water molecules around the catalytic and structural zinc (ZnC and ZnS) ions. The coordination of two conserved water molecules (W and WS) to ZnS and the H-bonding interaction of WS to S151 have indicated the plausible involvement of that metal ion in the catalytic process. Beside this the coupling of ZnC and ZnS metal ions (ZnC - W(H) (W(1))…..W(2) ….H(162) - ZnS) through two conserved hydrophilic centers (occupied by water molecules) may also provide some rational on the recognition of two zinc ions which were separated by ~13 Å in their X-ray structures. This unique recognition of both the Zn(+2) ions in the enzyme through conserved water molecules may be implemented/ exploited for the design of antiproteolytic agent using water mimic drug design protocol.

Protein thermal stability enhancement by designing salt bridges: a combined computational and experimental study.

PubMed

Lee, Chi-Wen; Wang, Hsiu-Jung; Hwang, Jenn-Kang; Tseng, Ching-Ping

2014-01-01

Protein thermal stability is an important factor considered in medical and industrial applications. Many structural characteristics related to protein thermal stability have been elucidated, and increasing salt bridges is considered as one of the most efficient strategies to increase protein thermal stability. However, the accurate simulation of salt bridges remains difficult. In this study, a novel method for salt-bridge design was proposed based on the statistical analysis of 10,556 surface salt bridges on 6,493 X-ray protein structures. These salt bridges were first categorized based on pairing residues, secondary structure locations, and Cα-Cα distances. Pairing preferences generalized from statistical analysis were used to construct a salt-bridge pair index and utilized in a weighted electrostatic attraction model to find the effective pairings for designing salt bridges. The model was also coupled with B-factor, weighted contact number, relative solvent accessibility, and conservation prescreening to determine the residues appropriate for the thermal adaptive design of salt bridges. According to our method, eight putative salt-bridges were designed on a mesophilic β-glucosidase and 24 variants were constructed to verify the predictions. Six putative salt-bridges leaded to the increase of the enzyme thermal stability. A significant increase in melting temperature of 8.8, 4.8, 3.7, 1.3, 1.2, and 0.7°C of the putative salt-bridges N437K-D49, E96R-D28, E96K-D28, S440K-E70, T231K-D388, and Q277E-D282 was detected, respectively. Reversing the polarity of T231K-D388 to T231D-D388K resulted in a further increase in melting temperatures by 3.6°C, which may be caused by the transformation of an intra-subunit electrostatic interaction into an inter-subunit one depending on the local environment. The combination of the thermostable variants (N437K, E96R, T231D and D388K) generated a melting temperature increase of 15.7°C. Thus, this study demonstrated a novel method for the thermal adaptive design of salt bridges through inference of suitable positions and substitutions.

High-pressure single-crystal synchrotron X-ray diffraction of kainite (KMg(SO4) Cl 3H2O)

NASA Astrophysics Data System (ADS)

Nazzareni, S.; Comodi, P.; Hanfland, M.

2018-03-01

Kainite (KMg(SO4) Cl 3H2O) is a "mixed-salt" sulfate from the group of evaporitic minerals more soluble than Ca-sulfate hydrate and NaCl. The compressibility and structural modifications of monoclinic (sp. gr. C2/m) kainite up to a pressure of 14 GPa were studied by high-pressure single-crystal synchrotron X-ray diffraction. Kainite remains stable over the investigated pressure range and no phase transition was recognised. The bulk modulus is K 0 = 31.6 (1) GPa, with K' fixed to 4, as obtained by fitting the P-volume data with a second-order Birch-Murnaghan EoS (BM2); instead of using a BM3 EoS, we obtained K 0 = 32.2(5) GPa, K' =3.8 (1). The linear moduli calculated for the lattice parameters fitting the data with a BM3 EoS are for a-axis M 0a = 117(4) GPa, Mpa = 11(1), for b-axis M 0b = 113(2) GPa, Mpc = 8.6(5), and c-axis M 0c = 68.2(3) GPa, Mpc = 14(1). Structure refinements showed a strong compression of the K polyhedra and in particular K(1) and K(3) polyhedra have similar polyhedral bulk moduli: K 0K(1) = 20.8(7) GPa, K'=4.8(3); K 0K(2) = 29(1) GPa, K'=8.1(6); K 0K(3) = 26(1) GPa, K'=4.2(4). The most compressible bond distances are K(1)-Cl(2) with a shortening of about 13%, K(1)-Cl(1) with a shortening of about 10%, K(3)-Ow(6) and K(3)-O8(B) both with a shortening of 9%. S-tetrahedra are almost incompressible and Mg-octahedra bulk moduli are K 0Mg(2) = 102(4) GPa, and K 0Mg(4) = 72(1) GPa, K 0Mg(1) = 41(4) GPa K'= 8.9(1.7), and K 0Mg(3) = 65(5) GPa K'= 10(2). The strain tensor analysis indicates that the most compressible direction of the kainite monoclinic structure is oriented 29.7(2)° from the c-axis in the (0 1 0) plane. The shortening of the K(1)-K(2) distance (from 4.219(4) Å at ambient P to 3.521(7) Å at 11.9 GPa) and the different compressibilities of the octahedra/tetrahedra may explain why the stiffer direction of kainite is in the a-c plane approximatively along the direction where K(1)-K(2) and Mg(4)-Mg(3)-Mg(4) polyhedra align. This may explain the anisotropic compressional behaviour of the crystallographic axes, where c is more compressible (by tetrahedral tilting mechanism) than a and b, where cation-cation repulsion and a more rigid configuration make these directions stiffer. Following the structure modification increasing pressure a new sets of hydrogens bonds could form as oxygens and chlorine atoms get at less than 3 Å distance from the Ow.

Isolation and structural characterization of sugarcane bagasse lignin after dilute phosphoric acid plus steam explosion pretreatment and its effect on cellulose hydrolysis.

PubMed

Zeng, Jijiao; Tong, Zhaohui; Wang, Letian; Zhu, J Y; Ingram, Lonnie

2014-02-01

The structure of lignin after dilute phosphoric acid plus steam explosion pretreatment process of sugarcane bagasse in a pilot scale and the effect of the lignin extracted by ethanol on subsequent cellulose hydrolysis were investigated. The lignin structural changes caused by pretreatment were identified using advanced nondestructive techniques such as gel permeation chromatography (GPC), quantitative (13)C, and 2-D nuclear magnetic resonance (NMR). The structural analysis revealed that ethanol extractable lignin preserved basic lignin structure, but had relatively lower amount of β-O-4 linkages, syringyl/guaiacyl units ratio (S/G), p-coumarate/ferulate ratio, and other ending structures. The results also indicated that approximately 8% of mass weight was extracted by pure ethanol. The bagasse after ethanol extraction had an approximate 22% higher glucose yield after enzyme hydrolysis compared to pretreated bagasse without extraction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low temperature structures of dCpG-proflavine. Conformational and hydration effects.

PubMed Central

Schneider, B; Ginell, S L; Berman, H M

1992-01-01

The structure of the complex of dCpG with proflavine was determined using x-ray data taken at -130 degrees C (low temperature) and at -2 degrees C (cold temperature) and compared with the structure of the complex determined previously at room temperature (Shieh, H. S., H. M. Berman, M. Dabrow, and S. Neidle. 1980. Nucleic Acids Res. 8:85-97). Low temperature was refined with 5,125 reflections between 8.0 and 0.93 A, Anisotropically modeled temperature factors were used for DNA/drug atoms and isotropic ones for water oxygens to R factor of 12.2% in P2(1)2(1)2; a = 32.853, b = 21.760, c = 13.296 A. Cold temperature was refined isotropically with 2,846 reflections 8.0-0.89 A to R = 15.1% in P2(1)2(1)2; a = 32.867, b = 22.356, c = 13.461 A. Both structures are very similar to the room temperature one, though some important differences were observed: one guanine sugar moiety is disordered and additional water molecules have been located that give rise to infinite polyhedral hydration networks. Images FIGURE 2 PMID:1489914

Low temperature structures of dCpG-proflavine.

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

Schneider, B.; Ginell, S. L.; Berman, H. M.

1992-12-01

The structure of the complex of dCpG with proflavine was determined using x-ray data taken at -130 degrees C (low temperature) and at -2 degrees C (cold temperature) and compared with the structure of the complex determined previously at room temperature (Shieh, H. S., H. M. Berman, M. Dabrow, and S. Neidle. 1980. Nucleic Acids Res. 8:85-97). Low temperature was refined with 5,125 reflections between 8.0 and 0.93 A, Anisotropically modeled temperature factors were used for DNA/drug atoms and isotropic ones for water oxygens to R factor of 12.2% in P2(1)2(1)2; a = 32.853, b = 21.760, c = 13.296more » A. Cold temperature was refined isotropically with 2,846 reflections 8.0-0.89 A to R = 15.1% in P2(1)2(1)2; a = 32.867, b = 22.356, c = 13.461 A. Both structures are very similar to the room temperature one, though some important differences were observed: one guanine sugar moiety is disordered and additional water molecules have been located that give rise to infinite polyhedral hydration networks.« less

Outcomes associated with initial versus later vancomycin use in patients with complicated skin and skin-structure infections.

PubMed

Itani, Kamal M F; Akhras, Kasem S; Stellhorn, Robert; Quintana, Alvaro; Budd, David; Merchant, Sanjay

2009-01-01

Delayed coverage of pathogens including meticillin-resistant Staphylococcus aureus (MRSA) in pneumonia and bacteraemia has been associated with increased mortality and length of hospital stay (LOS). However, less is known about the impact of delayed appropriate coverage in complicated skin and skin-structure infections (cSSSIs). To evaluate the clinical and economic outcomes associated with early versus late use of vancomycin in the management of patients hospitalized for cSSSIs. Retrospective analysis was performed using an inpatient claims database of >500 US hospitals in 2005. Using prescription claims, patients with primary or secondary cSSSI admissions were classified into three groups: 1 = early vancomycin monotherapy; 2 = early vancomycin combination therapy; 3 = late vancomycin therapy. Outcomes studied included LOS and inpatient hospital costs. One-way analysis of variance was used for unadjusted analysis and multivariate regression methods were used to control for co-variates. A total of 34,942 patients (27.78% of all patients with cSSSIs) were treated with vancomycin. Mean age was 54.7 years and 54.3% of the patients were males. Mean unadjusted total LOS was 8.46, 9.44 and 13.2 days, and hospital costs in 2005 values were USD10 211.94, USD12 361.94 and USD18 344.00 for groups 1, 2 and 3, respectively. In-hospital mortality rate was highest in group 3 (4.18%) and lowest in group 1 (1.75%). Generalized linear models used to control for potential confounding variables between early versus late vancomycin use suggest that among cSSSI patients late vancomycin use is an independent predictor of higher LOS and costs. In this large inpatient database, later vancomycin use in patients with cSSSIs appears to be significantly associated with higher LOS and total costs.

Molecular basis for methoxyamine initiated mutagenesis. 1H nuclear magnetic resonance studies of base-modified oligodeoxynucleotides.

PubMed

Stone, M J; Nedderman, A N; Williams, D H; Lin, P K; Brown, D M

1991-12-05

In order to reach a more detailed understanding of the mechanism of the mutagenic action of methoxyamine and of N4-methoxycytidine and its 2'-deoxyribo-analogue, the solution structures of the self-complementary octanucleotide, d(CGAATTCG) and its analogues, d(CGAATCCG), d(CGAATMCG) and d(CGAATPCG) (designated 8mer-AT, 8mer-AC, 8mer-AM, and 8mer-AP, respectively), were investigated by 1H nuclear magnetic resonance spectroscopy; M is N4-methoxycytosine (mo4C) and P is an analogue, the bicyclic dihydropyrimido[4,5-c][1,2]oxazin-7-one, in which the N-O bond is held in the anti configuration with respect to N3 of the cytosine ring. Correlated spectroscopy and nuclear Overhauser spectroscopy allowed assignment of the base, anomeric and H2'/H2" protons in 8mers-AT, -AM and -AP, and showed that all three had features consistent with a regular B-DNA duplex structure. Duplex-to-coil transition temperatures were determined to be 52(+/- 2) degrees C (8mer-AT), 51(+/- 2) degrees C (8mer-AP), 32(+/- 2) degrees C (8mer-AM); on the chemical shift timescale, the melting transition was fast for 8mer-AT and 8mer-AP, but slow for 8mer-AM. Imino proton spectra were indicative of Watson-Crick base-pairing in 8mers-AT, -AP and -AM. The 8mer-AP duplex had a structure and melting characteristics virtually identical with those of the 8mer-AT duplex. The preferred syn configuration of the methoxyl group in M had a destabilising effect on the 8mer-AM duplex. At low temperatures, the A.M base-pair was in fast equilibrium between Watson-Crick and wobble configurations, with the methoxyl function anti-oriented, but the melting transition was accompanied by isomerization of the methoxyl group to the syn conformation. This syn-anti isomerization was the rate-determining step in the duplex-to-coil transition. The 8mer-AC oligomer did not form a stable duplex.

Liquid petroleum gas sensing application of ZnO/CdO:ZnO nanocomposites at low temperature

NASA Astrophysics Data System (ADS)

Rajput, Jeevitesh K.; Pathak, T. K.; Kumar, V.; Swart, H. C.; Purohit, L. P.

2018-04-01

ZnO and CdO:ZnO nanoparticles are synthesized by sol-gel precipitation method. The structural analysis shows composite structure for CdO:ZnO nanoparticles with (002) and (111) phase. The SEM images show wedge like morphology and 3-D hexagonal morphology with ˜110 nm in size. The uniform growth of CdO:ZnO nanoparticles were observed in EDS element mapping image. LPG sensing was observed for CdO:ZnO nanoparticle with rapid sensing response 8.69% at operating temperature 50°C. This sensing response can be accounted due by absorption ions reactions at low operating temperature.

Expectancy for food or expectancy for chocolate reveals timing systems for metabolism and reward.

PubMed

Angeles-Castellanos, M; Salgado-Delgado, R; Rodríguez, K; Buijs, R M; Escobar, C

2008-07-31

The clock gene protein Per 1 (PER1) is expressed in several brain structures and oscillates associated with the suprachiasmatic nucleus (SCN). Restricted feeding schedules (RFS) induce anticipatory activity and impose daily oscillations of c-Fos and clock proteins in brain structures. Daily access to a palatable treat (chocolate) also elicits anticipatory activity and induces c-Fos expression mainly in corticolimbic structures. Here the influence of daily access to food or chocolate was explored by the analysis of the oscillatory patterns of PER1 in hypothalamic and corticolimbic structures. Wistar rats were exposed to RFS or to daily access to chocolate for 3 weeks. Persistence of food or chocolate entrained rhythms was determined 8 days after cessation of the feeding protocols. RFS and chocolate induced a phase shift in PER1 rhythmicity in corticolimbic structures with peak values at zeitgeber time 12 and a higher amplitude in the chocolate group. Both RFS and chocolate groups showed an upregulation of PER1 in the SCN. Food and chocolate entrained rhythms persisted for 8 days in behavior and in PER1 expression in the dorsomedial hypothalamic nucleus, accumbens, prefrontal cortex and central amygdala. The present data demonstrate the existence of different oscillatory systems in the brain that can be activated by entrainment to metabolic stimuli or to reward and suggest the participation of PER1 in both entraining pathways. Persistence and amplification of PER1 oscillations in structures associated with reward suggest that this oscillatory process is fundamental to food addictive behavior.

Chromophoric Nucleoside Analogues: Synthesis and Characterization of 6-Aminouracil-Based Nucleodyes.

PubMed

Freeman, Noam S; Moore, Curtis E; Wilhelmsson, L Marcus; Tor, Yitzhak

2016-06-03

Nucleodyes, visibly colored chromophoric nucleoside analogues, are reported. Design criteria are outlined and the syntheses of cytidine and uridine azo dye analogues derived from 6-aminouracil are described. Structural analysis shows that the nucleodyes are sound structural analogues of their native nucleoside counterparts, and photophysical studies demonstrate that the nucleodyes are sensitive to microenvironmental changes. Quantum chemical calculations are presented as a valuable complementary tool for the design of strongly absorbing nucleodyes, which overlap with the emission of known fluorophores. Förster critical distance (R0) calculations determine that the nucleodyes make good FRET pairs with both 2-aminopurine (2AP) and pyrrolocytosine (PyC). Additionally, unique tautomerization features exhibited by 5-(4-nitrophenylazo)-6-oxocytidine (8) are visualized by an extraordinary crystal structure.

AC impedance spectroscopy of NASICON type Na3Fe2(PO4)3 ceramic

NASA Astrophysics Data System (ADS)

Mandal, Biswajit; Thakur, A. K.

2018-05-01

Super ionic conductors (e.g.; A3M2(XO4)3, A=Li, Na) have received attention in applied research due to their interesting electrochemical property and inherently high ionic conductivity [1]. However, structural and compatibility requirements for fast ion transport is stringent and it plays a crucial role. In A3M2(XO4)3, a suitable cage formation in the crystal framework due to corner sharing arrangement of XO4 tetrahedra and MO6 octahedra creates voids that acts as host/guest site for cation transport. In this work, we report Nasicon structure Na3Fe2(PO4)3 (NFP) prepared via sol-gel route mediated by citric acid. Structural analysis confirmed that NFP sample belongs to monoclinic crystal structure having Cc space group (S. G. No 9) with lattice parameters, a=15.106 Å, b=8.722 Å, c=8.775 Å and β=124.96°. Electrical properties of the prepared sample have been studied by AC impedance spectroscopy technique. The AC conductivity results indicated typical signature of ionically conducting system.

Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2014-09-01

Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3 with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO matrix covered with silver oxide shell, resulting in high quality nanocomposite thin films. The embedment of polyvinylpyrrolidone inhibited the growth of silver nanoparticles and ITO annealed at 350 °C. Delafossite structure of tin-doped AgInO2 was found at higher annealing temperatures. XRD analysis and FESEM micrographs showed that the optimum temperature to prevent the formation of AgInO2 is 350 °C. The embedment of silver particles (5-10 nm) from reduction of silver ion in ITO thin films improved the electrical conductivity and optical transmittance of ITO nanolayers. The lowest stable sheet resistance of 1,952 Ω/Sq for a 321 nm thick and an average optical transmittance of 91.8 % in the visible region with a band gap of 3.43 eV were achieved for silver-doping content of 0.04 M.

Inhibitors of bacterial multidrug efflux pumps from the resin glycosides of Ipomoea murucoides.

PubMed

Chérigo, Lilia; Pereda-Miranda, Rogelio; Fragoso-Serrano, Mabel; Jacobo-Herrera, Nadia; Kaatz, Glenn W; Gibbons, Simon

2008-06-01

A reinvestigation of the CHCl 3-soluble extract from flowers of the Mexican medicinal arborescent morning glory, Ipomoea murucoides, through preparative-scale recycling HPLC, yielded six new pentasaccharides, murucoidins VI-XI (1- 6), as well as the known pescaprein III (7), stoloniferin I (8), and murucoidins I-V (9- 13). Their structures were characterized through the interpretation of their NMR spectroscopic and FABMS data. Compounds 1-6 were found to be macrolactones of three known glycosidic acids identified as simonic acids A and B, and operculinic acid A, with different fatty acids esterifying the same positions, C-2 on the second rhamnose unit and C-4 on the third rhamnose moiety. The lactonization site of the aglycone was placed at C-2 or C-3 of the second saccharide unit. The esterifying residues were composed of two short-chain fatty acids, 2-methylpropanoic and (2S)-methylbutyric acids, and two long-chain fatty acids, n-dodecanoic (lauric) acid and the new (8R)-(-)-8-hydroxydodecanoic acid. For the latter residue, its absolute configuration was determined by analysis of its Mosher ester derivatives. All members of the murucoidin series exerted a potentiation effect of norfloxacin against the NorA overexpressing Staphylococcus aureus strain SA-1199B by increasing the activity 4-fold (8 microg/mL from 32 microg/mL) at concentrations of 5-25 microg/mL. Stoloniferin I (8) enhanced norfloxacin activity 8-fold when incorporated at a concentration of 5 microg/mL. Therefore, this type of amphipathic oligosaccharide could be developed further to provide more potent inhibitors of this multidrug efflux pump.

[Isoflavone genistein-8-c-glycoside prevents the oxidative damages in structure and function of rat liver microsomal membranes].

PubMed

Zavodnik, L B

2003-01-01

Bioflavonoids (polyhydroxyphenols) are ubiquitous components of plants, fruits and vegetables; these compounds are efficient scavengers of free oxygen radicals and peroxides. The aim of this study was to investigate the antioxidant and radioprotective effects of genistein-8-C-glicoside (G8CG), an isoflavone, isolated from the flowers of Lipinus luteusl L. G8CG prevents dose-dependently the destruction of the cytochrome P-450 and its conversion to an inactive form cytochrome P-420, inhibits membrane lipid peroxidation and membrane SH-group oxidation in isolated rat liver microsomal membranes under tert-butylhydroperoxide-induced oxidative stress. Single whole-body gamma-irradiation (1 Gy) of rats results in blood plasma and liver microsomal membrane lipid peroxidation, impairments of microsomal membrane structure and function. Rat treatment with G8CG (75 mg/kg) developed the clear protective effect, stabilized membrane structure and improved the parameters of the monooxygenase function. We can conclude that G8CG can be used as antioxidant and radioprotective agent.

Structural versus electrical properties of an organic-inorganic hybrid material based on sulfate

NASA Astrophysics Data System (ADS)

Ben Rached, Asma; Guionneau, Philippe; Lebraud, Eric; Mhiri, Tahar; Elaoud, Zakaria

2017-01-01

A new organo-sulfate compound is obtained by slow evaporation at room temperature and is characterized by powder and single-crystal X-ray diffraction (XRD) at variable temperatures. The benzylammonium monohydrogenosulfate of formula C6H5CH2NH3+. HSO4-, denoted (BAS), crystallizes in the monoclinic system P21/c space group with the following parameters at room temperature: a=5.623(5)Å, b=20.239(5) Å, c=8.188(5)Å, β=94.104(5)°. The crystal structure consists of infinite parallel two-dimensional planes built by HSO4- anions and C6H5CH2NH3+ cations interconnected by strong O-H….. O and N-H….. O hydrogen bonds. A phase transition is detected at 350 K by differential scanning calorimetry (DSC) and confirmed by powder XRD. Conductivity measurements using the impedance spectroscopy technique allow to determine the conductivity relaxation parameters associated with the H+ conduction from an analysis of the M"/M"max spectrum measured in a wide temperature range. Transport properties of this material appear to be due to an H+ ion hopping mechanism.

Purification, crystallization and preliminary X-ray analysis of native and selenomethionine class I tagatose-1,6-bisphosphate aldolase from Streptococcus pyogenes.

PubMed

Liotard, Brigitte; Sygusch, Jurgen

2004-03-01

Tagatose-1,6-bisphosphate aldolase (EC 4.1.2.40) is situated at the branching of the tagatose-6-phosphate and Embden-Meyerhof-Parnas (glycolysis) metabolic pathways, where it catalyzes the reversible cleavage of tagatose-1,6-bisphosphate to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. The recombinant protein from Streptococcus pyogenes was overexpressed in Escherichia coli in its native and selenomethionine-derivative forms and purified using ion-exchange and hydrophobic interaction chromatography. Orthorhombic crystals suitable for structural analysis were obtained by the hanging-drop vapour-diffusion method for both isoforms. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 63.7, b = 108.1, c = 238.7 A for the native form and a = 64.1, b = 108.3, c = 239.8 A for the selenomethionine derivative. The asymmetric unit contains four protomers, corresponding to a crystal volume per protein weight (V(M)) of 2.8 A(3) Da(-1) and a solvent content of 56% by volume.

Ultrasound assisted synthesis, characterization and electrochemical study of a tetradentate oxovanadium diazomethine complex

NASA Astrophysics Data System (ADS)

Merzougui, Moufida; Ouari, Kamel; Weiss, Jean

2016-09-01

The oxovanadium (IV) complex ;VOL; of a tetradentate Schiff base ligand derived from the condensation of diaminoethane and 2-hydroxy-1-naphthaldehyde was efficiently prepared via ultrasound irradiation and the template effect of VO(acac)2. The resulting product was characterized by elemental analysis, infrared, electronic absorption and molar conductance measurement. Single X-ray structure analysis showed that the complex is a monomeric five-coordinate with a distorted square pyramidal geometry. It crystallizes in monoclinic system having unit cell parameters a = 8.3960 (5) Å; b = 12.5533 (8) Å and c = 18.7804 (11) Å; α = γ = 90°; β = 104.843°(2), with P 21/c space group. Cyclic voltammetry of the complex, carried out on a glassy carbon (GC) electrode in DMF, showed reversible cyclic voltammograms response in the potential range 0.15-0.60 V involving a single electron redox wave VV/VIV, the diffusion coefficient is determinedusing GC rotating disk electrode. The Levich plot Ilim = f(ω1/2), was used to calculate the diffusion-convection controlled currents.

Superconductivity and valence state in layered single-crystal HfAs1.67Te0.12

NASA Astrophysics Data System (ADS)

Peng, Jian; Yu, Jia; Zhang, Shuai; Chen, Genfu

2018-01-01

We report a detailed study on single crystals of HfAs1.67Te0.12 within a PbFCl-type layered structure. The single crystals of the title compound were successfully grown using a chemical transport reaction. The temperature dependence of electrical resistivity ρ (T), AC magnetic susceptibility {χ }{AC}(T) and specific heat C(T) show a bulk superconductivity with transition temperature T c = 1.67 K. The jump of C/T at T c is comparable to the traditional BCS weak-coupling model. A full H-T phase diagram is established using the results of ρ (T,H) and C(T) under fields, suggesting a rather weak anisotropy [({H}c2\\parallel {ab}(0)/{H}c2\\parallel c(0)] of 1.8 in orbital limit dominated three-dimension-like superconducting system. The mixed-valence states of Hf and As observed in the binding energy from x-ray photoelectron spectroscopy are consistent with the single-crystal x-ray diffraction analysis, indicating that the As-Te disorder prefers to occur in the [HfAs] layer and a large amount of vacancies are present in tetragonal As layer. As compared to HfAs1.7Se0.2 (T c = 0.52 K), a positive-like vacancy effect on T c has been confirmed in HfAs1.67Te0.12. The analysis of the Hall coefficient implies that the hole-type carriers dominate the transport properties, which is in good agreement with the hole pockets at Fermi surface obtained in a band structure calculation. The detailed study of single-crystal HfAs1.67Te0.12 provides a possible candidate to discuss the non-magnetic Kondo effect.

Conformational Preference and Donor Atom Interaction Leading to Hexacoordination vs Pentacoordination in Bicyclic Tetraoxyphosphoranes(1).

PubMed

Sherlock, David J.; Chandrasekaran, A.; Prakasha, T. K.; Day, Roberta O.; Holmes, Robert R.

1998-01-12

New bicyclic tetraoxyphosphoranes all containing a six-membered oxaphosphorinane ring, C(6)H(8)(CH(2)O)(2)P(OC(12)H(8))(OXyl) (1), (C(6)H(4)O)(2)P(OC(12)H(8))(OXyl) (2), CH(2)[(t-Bu)(2)C(6)H(2)O](2)P(OC(12)H(8))(OXyl) (3), O(2)S[(t-Bu)MeC(6)H(2)O](2)P(OC(12)H(8))(OXyl) (4), and S[(t-Bu)MeC(6)H(2)O](2)P(OC(12)H(8))(OXyl) (5), were synthesized by the oxidative addition reaction of the cyclic phosphine P(OC(12)H(8))(OXyl) (6) with an appropriate diol in the presence of N-chlorodiisopropylamine. X-ray analysis revealed trigonal bipyramidal (TBP) geometries for 1-4 where the dioxa ring varied in size from six- to eight-membered. With a sulfur donor atom as part of an eight-membered ring in place of a potential oxygen donor atom of a sulfone group as in 4, the X-ray study of 5 showed the formation of a hexacoordinated structure via a P-S interaction. Ring constraints are evaluated to give an order of conformational flexibility associated with the (TBP) tetraoxyphosphoranes 4 > 3 approximately 1 > 2 which parallels the degree of shielding from (31)P NMR chemical shifts: 4 > 3 > 1 > 2. The six- and seven-membered dioxa rings in 1 and 2, respectively, are positioned at axial-equatorial sites, whereas the eight-membered dioxa ring in 3 and 4 occupies diequatorial sites of a TBP. V-T (1)H NMR data give barriers to xylyl group rotation about the C-OXyl bond. The geometry of 5 is located along a coordinate from square pyramidal toward octahedral to the extent of 60.7%. Achieving hexacoordination in bicyclic tetraoxyphosphoranes of reduced electrophilicity relative to bicyclic pentaoxyphosphoranes appears to be dependent on the presence of a sufficiently strong donor atom.

A novel mutation causing nephronophthisis in the Lewis polycystic kidney rat localises to a conserved RCC1 domain in Nek8

PubMed Central

2012-01-01

Background Nephronophthisis (NPHP) as a cause of cystic kidney disease is the most common genetic cause of progressive renal failure in children and young adults. NPHP is characterized by abnormal and/or loss of function of proteins associated with primary cilia. Previously, we characterized an autosomal recessive phenotype of cystic kidney disease in the Lewis Polycystic Kidney (LPK) rat. Results In this study, quantitative trait locus analysis was used to define a ~1.6Mbp region on rat chromosome 10q25 harbouring the lpk mutation. Targeted genome capture and next-generation sequencing of this region identified a non-synonymous mutation R650C in the NIMA (never in mitosis gene a)- related kinase 8 ( Nek8) gene. This is a novel Nek8 mutation that occurs within the regulator of chromosome condensation 1 (RCC1)-like region of the protein. Specifically, the R650C substitution is located within a G[QRC]LG repeat motif of the predicted seven bladed beta-propeller structure of the RCC1 domain. The rat Nek8 gene is located in a region syntenic to portions of human chromosome 17 and mouse 11. Scanning electron microscopy confirmed abnormally long cilia on LPK kidney epithelial cells, and fluorescence immunohistochemistry for Nek8 protein revealed altered cilia localisation. Conclusions When assessed relative to other Nek8 NPHP mutations, our results indicate the whole propeller structure of the RCC1 domain is important, as the different mutations cause comparable phenotypes. This study establishes the LPK rat as a novel model system for NPHP and further consolidates the link between cystic kidney disease and cilia proteins. PMID:22899815

The crystal structure of the Hsp90 co-chaperone Cpr7 from Saccharomyces cerevisiae.

PubMed

Qiu, Yu; Ge, Qiangqiang; Wang, Mingxing; Lv, Hui; Ebrahimi, Mohammad; Niu, Liwen; Teng, Maikun; Li, Xu

2017-03-01

The versatility of Hsp90 can be attributed to the variety of co-chaperone proteins that modulate the role of Hsp90 in many cellular processes. As a co-chaperone of Hsp90, Cpr7 is essential for accelerating the cell growth in an Hsp90-containing trimeric complex. Here, we report the crystal structure of Cpr7 at a resolution of 1.8Å. It consists of an N-terminal PPI domain and a C-terminal TPR domain, and exhibits a U-shape conformation. Our studies revealed the aggregation state of Cpr7 in solution and the interaction properties between Cpr7 and the MEEVD sequence from the C-terminus of Hsp90. In addition, the structure and sequence analysis between Cpr7 and homologues revealed the structure basis both for the function differences between Cpr6 and Cpr7 and the functional complements between Cns1 and Cpr7. Our studies facilitate the understanding of Cpr7 and provide decent insights into the molecular mechanisms of the Hsp90 co-chaperone pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

Crystal structure and cation exchanging properties of a novel open framework phosphate of Ce (IV)

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

Bevara, Samatha; Achary, S. N., E-mail: sachary@barc.gov.in; Tyagi, A. K.

2016-05-23

Herein we report preparation, crystal structure and ion exchanging properties of a new phosphate of tetravalent cerium, K{sub 2}Ce(PO{sub 4}){sub 2}. A monoclinic structure having framework type arrangement of Ce(PO{sub 4}){sub 6} units formed by C2O{sub 8} square-antiprism and PO{sub 4} tetrahedra is assigned for K{sub C}e(PO{sub 4}){sub 2}. The K{sup +} ions are occupied in the channels formed by the Ce(PO{sub 4})6 and provide overall charge neutrality. The unique channel type arrangements of the K+ make them exchangeable with other cations. The ion exchanging properties of K2Ce(PO4)2 has been investigated by equilibrating with solution of 90Sr followed by radiometricmore » analysis. In optimum conditions, significant exchange of K+ with Sr2+ with Kd ~ 8000 mL/g is observed. The details of crystal structure and ion exchange properties are explained and a plausible mechanism for ion exchange is presented.« less

Analysis of simple 2-D and 3-D metal structures subjected to fragment impact

NASA Technical Reports Server (NTRS)

Witmer, E. A.; Stagliano, T. R.; Spilker, R. L.; Rodal, J. J. A.

1977-01-01

Theoretical methods were developed for predicting the large-deflection elastic-plastic transient structural responses of metal containment or deflector (C/D) structures to cope with rotor burst fragment impact attack. For two-dimensional C/D structures both, finite element and finite difference analysis methods were employed to analyze structural response produced by either prescribed transient loads or fragment impact. For the latter category, two time-wise step-by-step analysis procedures were devised to predict the structural responses resulting from a succession of fragment impacts: the collision force method (CFM) which utilizes an approximate prediction of the force applied to the attacked structure during fragment impact, and the collision imparted velocity method (CIVM) in which the impact-induced velocity increment acquired by a region of the impacted structure near the impact point is computed. The merits and limitations of these approaches are discussed. For the analysis of 3-d responses of C/D structures, only the CIVM approach was investigated.

Structure of Atg7 Alone and its Atg8-Bound Forms

NASA Astrophysics Data System (ADS)

Noda, Nobuo

Atg7 is a noncanonical E1 enzyme that activates Atg8 and transfers it to Atg3 (E2 enzyme), thus playing an essential role in conjugating Atg8 with phosphatidylethanolamine and thus in autophagy. Atg7 protomer is comprised of two globular domains, the N-terminal domain (NTD) and the C-terminal domain (CTD), and forms a homodimer through CTD. Atg7-Atg8 complex structures and biochemical analyses revealed that Atg8 is initially recognized by the C-terminal tail of CTD and is then transferred to the adenylation domain in CTD, where Atg8 Gly116 is adenylated and thioester-linked to the catalytic cysteine of Atg7. Atg8 is then transferred to Atg3 bound to the NTD of the opposite protomer within an Atg7 dimer via a trans mechanism.

Synthesis, structure and physicochemical characterization of the hybrid material [C6H16N2O]2 SnCl6·2Cl·2H2O

NASA Astrophysics Data System (ADS)

Belhaj Salah, S.; Pereira da Silva, P. S.; Lefebvre, F.; Ben Nasr, C.; Ammar, S.; Mrad, M. L.

2017-04-01

The current study reports the chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel compound [C6H16N2O]2SnCl6·2Cl·2H2O. This compound crystallizes in the triclinic system (space group P - 1, Z = 1) with the following unit cell dimensions: a = 7.9764(9), b = 8.2703(9), c = 12.1103(14)Å, α = 84.469(6), β = 75.679(6), and γ = 64.066(5)°. The structure was solved using 3093 independent reflections down to R = 0.020. The atomic arrangement shows alternation of organic and inorganic entities. The cohesion between these entities is ensured by Nsbnd H…Cl and Osbnd H…Cl hydrogen bonds that build a three-dimensional network. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated for intermolecular interactions. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the IR and NMR bands. X-ray powder, XPS and UV spectrum have been carried out. The DSC profile shows that the title material exhibits dehydration at 339 K.

Interaction of sulfur dioxide with titanium-carbide nanoparticles and surfaces: A density functional study

NASA Astrophysics Data System (ADS)

Liu, Ping; Rodriguez, José A.

2003-11-01

In the control of environmental pollution, metal carbides are potentially useful for trapping and destroying sulfur dioxide (SO2). In the present study, the density functional theory was employed to study the surface structures and electronic properties of the adsorbed SO2 on titanium carbides: metcar Ti8C12, nanocrystal Ti14C13, and a bulk TiC(001) surface. The geometries and orientations of SO2 were fully optimized on all these substrates. Our calculations show that, in spite of the high C/Ti ratio and C2 groups, metcar Ti8C12 exhibits extremely high activity towards SO2. The S-O bonds of SO2 spontaneously break on Ti8C12. The products of the decomposition reaction (S, O) interact simultaneously with Ti and C sites. The C atoms are not simple spectators, and their participation in the dissociation of SO2 is a key element for the energetics of this process. Nanocrystal Ti14C13 also displays a strong interaction with SO2. Although the dissociation of SO2 on Ti14C13 cannot proceed as easily as that on Ti8C12, it could occur by thermal activation even at very low temperature. SO2 is weakly bonded with the bulk TiC(001) surface. By thermal activation the dissociation of SO2 on a TiC(001) surface may also take place but it should be much more difficult than that on Ti14C13. Therefore, we suggest that the carbide nanoparticles (Ti8C12 and Ti14C13) should have special chemical activity towards SO2 removal associated with their "magic" structures.

Progesterone binding nano-carriers based on hydrophobically modified hyperbranched polyglycerols

NASA Astrophysics Data System (ADS)

Alizadeh Noghani, M.; Brooks, D. E.

2016-02-01

Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models.Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models. Electronic supplementary information (ESI) available: Fig. S-1: chemical structure of progesterone (Pro). Fig. S-2: 1H NMR spectrum of HPG-C8-MPEG. Fig. S-3: GPC chromatogram of HPG-C8-MPEG. Fig. S-4: 1H NMR spectrum of HPG-C12-MPEG. Fig. S-5: GPC chromatogram of HPG-C8-MPEG. Fig. S-6: FTIR spectrum of HPG-C8-MPEG. Fig. S-7: inverse-gated 13C NMR spectrum of HPG-C8-MPEG in methanol-d4. Fig. S-8: semi-log plot to determine initial rapid release kinetics for HPG-C8-MPEG/Pro in PBS. Fig. S-9: semi-log plot to determine secondary slow release kinetics for HPG-C8-MPEG/Pro in PBS. Fig. S-10: semi-log plot illustrating the kinetics of Pro release from HPG-C8-MPEG/Pro in plasma. Fig. S-11: dependence of k1 and Vp - Va. Fig. S-12: correlation between the maximum binding capacity of HPG-Cn-MPEG polymeric systems for binding Pro and their total mass of alkyl carbon external to the oxygen (R2 = 0.77 and p < 0.025). Table S-1: effect of loaded Pro on HPG-Cn-MPEG size. Fig. S-13. DLS size determination of HPG-C10-MPEG at 2 mg ml-1 (on the left) and HPG-C10-MPEG/Pro at 2 mg ml-1 of polymer and 25 μg ml-1 of Pro (on the right). The minor population of larger particles was reduced in diameter by Pro binding, illustrated above, consistent with an earlier report.11 See DOI: 10.1039/c5nr08175k

One-pot facile synthesis of 4-amino-1,8-naphthalimide derived Tröger's bases via a nucleophilic displacement approach.

PubMed

Shanmugaraju, Sankarasekaran; McAdams, Deirdre; Pancotti, Francesca; Hawes, Chris S; Veale, Emma B; Kitchen, Jonathan A; Gunnlaugsson, Thorfinnur

2017-09-13

We report here a novel one-pot synthetic strategy for the synthesis of a family of N-alkyl-1,8-naphthalimide based Tröger's bases via a nucleophilic substitution reaction of a common 'precursor' (or a 'synthon') N-aryl-1,8-naphthalimide Tröger's base heated at 80 °C in neat aliphatic primary amine, in overall yield of 65-96%. This methodology provides an efficient and one-step facile route to design 1,8-naphthalimide derived Tröger's base structures in analytically pure form without the use of column chromatography purification, that can be used in medicinal chemistry and as supramolecular scaffolds. We also report the formation of the corresponding anhydride, and the crystallographic analysis of two of the resulting products, that of the N-phenyl-4-amino-1,8-naphthalimide and the anhydride derived Tröger's bases.

Hydrogen-bonded networks of [Fe(bpp)2]2+ spin crossover complexes and dicarboxylate anions: structural and photomagnetic properties.

PubMed

Jornet-Mollá, Verónica; Duan, Yan; Giménez-Saiz, Carlos; Waerenborgh, João C; Romero, Francisco M

2016-11-28

The paper reports the syntheses, crystal structures, thermal and (photo)magnetic properties of spin crossover salts of formula [Fe(bpp) 2 ](C 6 H 8 O 4 )·4H 2 O (1·4H 2 O), [Fe(bpp) 2 ](C 8 H 4 O 4 )·2CH 3 OH·H 2 O (2·2MeOH·H 2 O) and [Fe(bpp) 2 ](C 8 H 4 O 4 )·5H 2 O (2·5H 2 O) (bpp = 2,6-bis(pyrazol-3yl)pyridine; C 6 H 8 O 4 = adipate dianion; C 8 H 4 O 4 = terephthalate dianion). The salts exhibit an intricate network of hydrogen bonds between low-spin iron(ii) complexes and carboxylate dianions, with solvent molecules sitting in the voids. Desolvation is accompanied by a low-spin (LS) to high-spin (HS) transformation in the materials. The dehydrated phase 2 undergoes a two-step transition with a second step showing thermal hysteresis (T 1/2 ↑ = 139 K and T 1/2 ↓ = 118 K). 2 displays a quantitative LS to HS photomagnetic conversion, with a T(LIESST) value of 63 K.

Sesquiterpenes from Curcuma wenyujin with their inhibitory activities on nitric oxide production in RAW 264.7 cells.

PubMed

Gao, Suyu; Xia, Guiyang; Wang, Liqing; Zhou, Li; Zhao, Feng; Huang, Jian; Chen, Lixia

2017-03-01

One new sesquiterpene, 7α,11-epoxy-6α-hydroxy-carabrane-4,8-dione, along with 10 known ones were isolated from the essential oil of Curcuma wenyujin Y.H. Chen et C. Ling. Their structures were established based on extensive spectroscopic analysis. The absolute configuration of compound 1 was determined by the CD analysis of the insitu formed [Rh 2 (OCOCF 3 ) 4 ] complex, and the CD data analysis based on the octane rule of cyclohexanone. The inhibitory effects of these sesquiterpenes on nitric oxide production in lipopolysaccharide-activated macrophages were also evaluated. Furthermore, the biosynthesis pathway of the isolated compounds was proposed.

Directed divergent evolution of a thermostable D-tagatose epimerase towards improved activity for two hexose substrates.

PubMed

Bosshart, Andreas; Hee, Chee Seng; Bechtold, Matthias; Schirmer, Tilman; Panke, Sven

2015-03-02

Functional promiscuity of enzymes can often be harnessed as the starting point for the directed evolution of novel biocatalysts. Here we describe the divergent morphing of an engineered thermostable variant (Var8) of a promiscuous D-tagatose epimerase (DTE) into two efficient catalysts for the C3 epimerization of D-fructose to D-psicose and of L-sorbose to L-tagatose. Iterative single-site randomization and screening of 48 residues in the first and second shells around the substrate-binding site of Var8 yielded the eight-site mutant IDF8 (ninefold improved kcat for the epimerization of D-fructose) and the six-site mutant ILS6 (14-fold improved epimerization of L-sorbose), compared to Var8. Structure analysis of IDF8 revealed a charged patch at the entrance of its active site; this presumably facilitates entry of the polar substrate. The improvement in catalytic activity of variant ILS6 is thought to relate to subtle changes in the hydration of the bound substrate. The structures can now be used to select additional sites for further directed evolution of the ketohexose epimerase. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recyclable Thermoresponsive Polymer-β-Glucosidase Conjugate with Intact Hydrolysis Activity.

PubMed

Mukherjee, Ishita; Sinha, Sushant K; Datta, Supratim; De, Priyadarsi

2018-06-11

β-Glucosidase (BG) catalyzes the hydrolysis of cellobiose to glucose and is a rate-limiting enzyme in the conversion of lignocellulosic biomass to sugars toward biofuels. Since the cost of enzyme is a major contributor to biofuel economics, we report the bioconjugation of a temperature-responsive polymer with the highly active thermophilic β-glucosidase (B8CYA8) from Halothermothrix orenii toward improving enzyme recyclability. The bioconjugate, with a lower critical solution temperature (LCST) of 33 °C withstands high temperatures up to 70 °C. Though the secondary structure of the enzyme in the conjugate is slightly distorted with a higher percentage of β-sheet like structure, the stability and specific activity of B8CYA8 in the conjugate remains unaltered up to 30 °C and retains more than 70% specific activity of the unmodified enzyme at 70 °C. The conjugate can be reused for β-glucosidic bond cleavage of cellobiose for at least four cycles without any significant loss in specific activity.