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Sample records for synthesis revised structure

  1. Total synthesis and structural revision of (+)-amphidinolide W.

    PubMed

    Ghosh, Arun K; Gong, Gangli

    2004-03-31

    An enantioselective first total syntheis of amphidinolide W (2) and a revision of its C6 absolute stereochemistry (1) are described. Amphidinolide W (1), a 12-membered macrolide isolated from Amphidinium sp., has shown potent antitumor properties against a variety of NCI tumor cell lines. The synthesis is convergent, and four of the five chiral centers were derived through asymmetric synthesis. The synthesis features Sharpless asymmetric dihydroxylation, diastereoselective alkylation, efficient cross metathesis of functionalized substrates, and novel functional group transformations using selective lipase-catalyzed hydrolysis of the primary acetate group. Of particular note, the C6 absolute stereochemistry of amphidinolide W (1) has now been revised through our current synthesis.

  2. Survey of marine natural product structure revisions: a synergy of spectroscopy and chemical synthesis.

    PubMed

    Suyama, Takashi L; Gerwick, William H; McPhail, Kerry L

    2011-11-15

    The structural assignment of new natural product molecules supports research in a multitude of disciplines that may lead to new therapeutic agents and or new understanding of disease biology. However, reports of numerous structural revisions, even of recently elucidated natural products, inspired the present survey of techniques used in structural misassignments and subsequent revisions in the context of constitutional or configurational errors. Given the comparatively recent development of marine natural products chemistry, coincident with modern spectroscopy, it is of interest to consider the relative roles of spectroscopy and chemical synthesis in the structure elucidation and revision of those marine natural products that were initially misassigned. Thus, a tabulated review of all marine natural product structural revisions from 2005 to 2010 is organized according to structural motif revised. Misassignments of constitution are more frequent than perhaps anticipated by reliance on HMBC and other advanced NMR experiments, especially when considering the full complement of all natural products. However, these techniques also feature prominently in structural revisions, specifically of marine natural products. Nevertheless, as is the case for revision of relative and absolute configuration, total synthesis is a proven partner for marine, as well as terrestrial, natural products structure elucidation. It also becomes apparent that considerable 'detective work' remains in structure elucidation, in spite of the spectacular advances in spectroscopic techniques. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Synthesis-Guided Structure Revision of the Sarcodonin, Sarcoviolin and Hydnellin Natural Product Family

    PubMed Central

    Lin, David W.; Masuda, Takeshi; Biskup, Moritz B.; Nelson, Jonathan D.; Baran, Phil S.

    2011-01-01

    A sweeping structural revision of the sarcodonin natural product family (published structures: 1a–13a) is proposed after extensive studies aimed at their chemical synthesis. Key features of revised structure 1b include replacement of the N,N-dioxide moiety with an oxime, ring opening of the central diketopiperazine, and transposition of the terphenyl wing from the 1β-2β position of 1a to the 2β-3β position of 1b. This structure revision arose from the serendipitous synthesis of a benzodioxane aminal (44) whose structure was unambiguously determined by X-Ray crystallography and whose spectral properties bore considerable resemblance to the published data for the sarcodonins. A versatile new method for O-arylation of hydroxamic acids is also reported herein, as well as a manganese(III)-mediated α-oxidation of hydroxamic acids to aminals. PMID:21250718

  4. Total synthesis of a new cytotoxic acetogenin, jimenezin, and the revised structure.

    PubMed

    Takahashi, S; Maeda, K; Hirota, S; Nakata, T

    1999-12-16

    The first total synthesis of jimenezin was achieved by using carbohydrates as chiral building blocks, thus revising the proposed structure 1 to 2. The key steps in this synthesis include an efficient construction of the THP-THF fragments 3 and 16 through a stereoselective condensation between the pyranyl aldehyde 5 and the acetylene derivative 6, and a palladium-catalyzed coupling reaction of 3 or 16 with a terminal butenolide 4.

  5. The asymmetric total synthesis of cinbotolide: a revision of the original structure.

    PubMed

    Botubol, José Manuel; Durán-Peña, María Jesús; Macías-Sánchez, Antonio J; Hanson, James R; Collado, Isidro G; Hernández-Galán, Rosario

    2014-12-05

    The structure 3,4-dihydroxy-2,4,6,8-tetramethyldec-8-enolide (1) was assigned to a metabolite of Botrytis cinerea, but the spectra of several synthetic analogues had significant differences from that of 1. Examination of the constituents of a B. cinerea mutant that overproduces polyketides gave sufficient quantities of 1, now named cinbotolide, for chemical transformations. These led to a revised γ-butyrolactone structure for the metabolite. This structure has been confirmed by an asymmetric total synthesis, which also established its absolute configuration.

  6. Synthesis and Structure Revision of Dimeric Tadalafil Analogue Adulterants in Dietary Supplements.

    PubMed

    Mandava, Suresh; Ganganna, Bogonda; Hwang, Jungjoong; Jang, Younchang; Hwang, Jiho; Samala, Mallesham; Kim, Ki-Bbeum; Park, Haeil; Lee, Ji Hyun; Baek, Sun Young; Lee, Jongkook

    2017-01-01

    A number of phosphodiesterase 5 (PDE5) inhibitors approved by authorities have been used successfully in the treatment of erectile dysfunction. These medicines must be prescribed carefully due to their adverse effects, but they and their analogues are being illegally added to dietary supplements. These illegal dietary supplements pose a significant risk to public health. Several dimeric tadalafil analogues have been synthesized for use as reference standards in the inspection of functional foods that are mainly advertised as sexual enhancement products. During the course of this synthesis, 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxid hexafluorophosphate (HATU) was proven to be the reagent of choice for amide coupling to produce these dimeric tadalafil analogues. Moreover, the trans-isomer structures tentatively assigned for the isolated dimeric tadalafil analogues (bisprehomotadalafil and bisprecyclopentyltadalafil) found in dietary supplements are now revised to cis-isomer structures.

  7. Total Synthesis of Viridicatumtoxin B and Analogues Thereof: Strategy Evolution, Structural Revision, and Biological Evaluation

    PubMed Central

    2015-01-01

    The details of the total synthesis of viridicatumtoxin B (1) are described. Initial synthetic strategies toward this intriguing tetracycline antibiotic resulted in the development of key alkylation and Lewis acid-mediated spirocyclization reactions to form the hindered EF spirojunction, as well as Michael–Dieckmann reactions to set the A and C rings. The use of an aromatic A-ring substrate, however, was found to be unsuitable for the introduction of the requisite hydroxyl groups at carbons 4a and 12a. Applying these previous tactics, we developed stepwise approaches to oxidize carbons 12a and 4a based on enol- and enolate-based oxidations, respectively, the latter of which was accomplished after systematic investigations that revealed critical reactivity patterns. The herein described synthetic strategy resulted in the total synthesis of viridicatumtoxin B (1), which, in turn, formed the basis for the revision of its originally assigned structure. The developed chemistry facilitated the synthesis of a series of viridicatumtoxin analogues, which were evaluated against Gram-positive and Gram-negative bacterial strains, including drug-resistant pathogens, revealing the first structure–activity relationships within this structural type. PMID:25317739

  8. Evolution of a Strategy for the Synthesis of Structurally Complex Batzelladine Alkaloids. Enantioselective Total Synthesis of the Proposed Structure of Batzelladine F and Structural Revision

    PubMed Central

    Cohen, Frederick; Overman, Larry E.

    2008-01-01

    Stereoselective synthesis of octahydro-5,6,6a-triazaacenaphthalenes 29 and 34 having the anti relationship of the angular hydrogens flanking the pyrrolidine nitrogen confirmed suspicions that the relative configuration of the left hand tricyclic guanidine fragment of batzelladine F should be revised to have the syn relationship of these hydrogens. Several strategies were examined for coupling tricyclic guanidine fragments to prepare potential structures for batzelladine F. Eventually a convergent synthesis strategy was devised, whose central step was a fragment-coupling tethered-Biginelli reaction (Scheme 17). Using this approach we synthesized four potential structures of batzelladine F, 35–38. None of these compounds, nor their enantiomers, were identical to natural batzelladine F. Reinvestigation of mass spectra of natural batzelladine F, and fragments 88 and 89 obtained upon saponification of batzelladine F, demonstrated that the originally proposed connectivity of this alkaloid was also incorrect. The revised connectivity, 90, of natural batzelladine F depicted in Scheme 21 is proposed. PMID:16492043

  9. Evolution of a strategy for the synthesis of structurally complex batzelladine alkaloids. Enantioselective total synthesis of the proposed structure of batzelladine F and structural revision.

    PubMed

    Cohen, Frederick; Overman, Larry E

    2006-03-01

    Stereoselective synthesis of octahydro-5,6,6a-triazaacenaphthalenes 29 and 34 having the anti-relationship of the angular hydrogens flanking the pyrrolidine nitrogen confirmed suspicions that the relative configuration of the left-hand tricyclic guanidine fragment of batzelladine F should be revised to have the syn relationship of these hydrogens. Several strategies were examined for coupling tricyclic guanidine fragments to prepare potential structures for batzelladine F. Eventually, a convergent synthesis strategy was devised, whose central step was a fragment-coupling tethered-Biginelli reaction (Scheme 17). Using this approach we synthesized four potential structures of batzelladine F, 35-38. None of these compounds, nor their enantiomers, were identical to natural batzelladine F. Reinvestigation of mass spectra of natural batzelladine F, and fragments 88 and 89 obtained upon saponification of batzelladine F, demonstrated that the originally proposed connectivity of this alkaloid was also incorrect. The revised connectivity, 90, of natural batzelladine F depicted in Scheme 21 is proposed.

  10. Total Synthesis and Structural Revision of Vannusals A and B. Synthesis of the True Structures of Vannusals A and B

    PubMed Central

    Ortiz, Adrian; Zhang, Hongjun; Guella, Graziano

    2010-01-01

    Having determined, through total synthesis, that the originally assigned structure of vannusals A and B were incorrect, we set out to uncover the identity of the true structures of these novel marine natural products. Our search was based on intelligence gathered by NMR spectroscopy and chemical synthesis and took us through the total synthesis of eight diastereomeric vannusal B structures [2, d-2, 3, d-3, 4, d-4, 5, and d-5, Figure 1]. The true structures of vannusals A and B were finally determined to be d-5 and d-1, respectively. Their total synthesis was based on a highly convergent and efficient strategy that involved fragments vinyl iodide (−)-6 and aldehyde (±)-94, and featured a stereoselective lithium-mediated coupling reaction and a samarium-induced cyclization process that forged the final ring of the carbon framework. The synthetic strategies and technologies developed in these investigations expand the scope of chemical synthesis and render these compounds readily available for biological evaluation, while the NMR spectroscopic insights gained should prove useful in future structural determination endeavors. PMID:20443558

  11. Chemical synthesis of dendrotoxin-I: revision of the reported structure.

    PubMed

    Nishio, H; Inui, T; Nishiuchi, Y; De Medeiros, C L; Rowan, E G; Harvey, A L; Katoh, E; Yamazaki, T; Kimura, T; Sakakibara, S

    1998-05-01

    Dendrotoxin I (DTX-I) is a 60-residue peptide from the venom of the black mamba snake Dendroaspis polylepis, which binds to neuronal K+ channels. The structure reported previously for DTX-I was synthesized for the first time by a solution procedure. The synthetic product was confirmed to have the correct primary and disulfide structure determined by peptide mapping, sequence analysis and mass measurements. Comparison of synthetic DTX-I with the natural one by high-performance liquid chromatography and capillary zone electrophoresis, as well as by sequence analysis, revealed that the Asn residue at position 12 in the synthetic peptide was Asp in the natural product. Synthesis of DTX-I with Asp at position 12 gave a peptide identical with the natural product in all aspects. NMR analysis of synthetic [Asn12]- and [Asp12]-DTX-I also supported our findings that the Asn residue at position 12 in the DTX-I molecule should be revised as Asp. [Asn12]- and [Asp12]-DTX-I had very similar binding affinities when tested against radiolabeled dendrotoxin binding to rat brain synaptosomal membranes.

  12. Synthesis and structure revision of the C43-C67 part of amphidinol 3.

    PubMed

    Ebine, Makoto; Kanemoto, Mitsunori; Manabe, Yoshiyuki; Konno, Yosuke; Sakai, Ken; Matsumori, Nobuaki; Murata, Michio; Oishi, Tohru

    2013-06-07

    Stereoselective synthesis of the C43-C67 part of amphidinol 3 (AM3) and its C51-epimer was achieved starting from a common intermediate corresponding to the tetrahydropyran moiety of AM3, via asymmetric oxidations and Julia-Kocienski olefination. By comparing NMR data of the synthetic specimens with those of AM3, the absolute configuration at C51 of AM3 was revised from R to S.

  13. Remote Stereoinductive Intramolecular Nitrile Oxide Cycloaddition: Asymmetric Total Synthesis and Structure Revision of (-)-11β-Hydroxycurvularin.

    PubMed

    Choe, Hyeonjeong; Pham, Thuy Trang; Lee, Joo Yun; Latif, Muhammad; Park, Haeil; Kang, Young Kee; Lee, Jongkook

    2016-03-18

    The first total synthesis and structure revision of (-)-11β-hydroxycurvularin (1b), a macrolide possessing a β-hydroxyketone moiety, were accomplished. The β-hydroxyketone moiety in this natural product was introduced by cleavage of the N-O bond in an isoxazoline ring that was formed diastereoselectively in a 1,5-remote stereocontrolled fashion by employing intramolecular nitrile oxide cycloaddition.

  14. Total Synthesis and Structural Revision of Vannusals A and B. Synthesis of the Originally Assigned Structure of Vannusal B

    PubMed Central

    Nicolaou, K. C.; Ortiz, Adrian; Zhang, Hongjun; Dagneau, Philippe; Lanver, Andreas; Jennings, Michael P.; Arseniyadis, Stellios; Faraoni, Raffaella; Lizos, Dimitrios E.

    2010-01-01

    The total synthesis of the originally assigned structure of vannusal B (2) and its diastereomer (d-2) are described. Initial forays into these structures with model systems revealed the viability of a metathesis-based approach and a SmI2-mediated strategy for the key cyclization to forge the central region of the molecule, ring C. The former approach was abandoned in favor of the latter when more functionalized substrates failed to enter the cyclization process. The successful, devised convergent strategy based on the SmI2-mediated ring closure utilized vinyl iodide (−)-26 and aldehyde fragment (±)-86 as key building blocks, whose lithium-mediated coupling led to isomeric coupling products (+)-87 and (−)-88. These intermediates were separately converted to precursors (+)-25 and (−)-97, which cyclized under the influence of SmI2–HMPA to afford products (−)-90/(−)-91 and (+)-98, respectively. The former two intermediates were converted to vannusal B structure 2 while the latter gave rise to its diastereomeric structure d-2, neither of which exhibited the reported spectroscopic data of the natural product. These investigations led to the discovery and development of a number of new synthetic technologies that set the stage for the solution of the vannusal structural conundrum. PMID:20443561

  15. On the structure of palau'amine: evidence for the revised relative configuration from chemical synthesis.

    PubMed

    Lanman, Brian A; Overman, Larry E; Paulini, Ralph; White, Nicole S

    2007-10-24

    Hexacyclic congeners 3 and 4 of palau'amine, which incorporate both guanidine functional groups and have the cis configuration of the azabicyclo[3.3.0]octane core, are prepared in 14 steps from cycloadduct 6. Synthetic access to these analogues allows the first direct comparison of NMR data for hexacyclic diguanidine structures having the originally proposed cis-azabicyclo[3.3.0]octane fragment with data for natural alkaloids of the palau'amine family. This comparison provides convincing evidence in favor of the recently proposed structural revision of these marine alkaloids, fully supporting the trans configuration of the central azabicyclo[3.3.0]octane ring system of palau'amine and congeners.

  16. On the Structure of Palau’amine: Evidence for the Revised Relative Configuration from Chemical Synthesis

    PubMed Central

    Lanman, Brian A.; Overman, Larry E.; Paulini, Ralph; White, Nicole S.

    2008-01-01

    Hexacyclic congeners 2 and 3 of palau’amine, which incorporate both guanidine functional groups and have the cis configuration of the azabicyclo[3.3.0]octane core, are prepared in 14 steps from cycloadduct 6. Synthetic access to these analogs allows the first direct comparison of NMR data for hexacyclic diguanidine structures having the originally proposed cis-azabicyclo[3.3.0]octane fragment with data for natural alkaloids of the palau’amine family. This comparison provides convincing evidence in favor of the recently proposed structural revision of these marine alkaloids, fully supporting the trans configuration of the central azabicyclo[3.3.0]octane ring system of palau’amine and congeners. PMID:17902668

  17. Dehydromicrosclerodermin B and Microsclerodermin J: Total Synthesis and Structural Revision

    PubMed Central

    Melikhova, Ekaterina Y.; Pullin, Robert D. C.; Winter, Christian

    2016-01-01

    Abstract The total synthesis of dehydromicrosclerodermin B and microsclerodermin J is described. Efficient approaches to the unusual amino acids in the target molecules were developed on the basis of a Negishi coupling (for Trp‐2‐CO2H) and Blaise reaction (for Pyrr). An incorrect assignment of the pyrrolidinone stereochemistry of both compounds was confirmed by synthesizing epimers of the proposed structures. The spectroscopic data of these epimers were in complete agreement with those for the naturally derived material. PMID:27418203

  18. Synthesis of iso-epoxy-amphidinolide N and des-epoxy-caribenolide I structures. Revised strategy and final stages.

    PubMed

    Nicolaou, K C; Bulger, Paul G; Brenzovich, William E

    2006-06-07

    A general and highly convergent synthetic route to the macrocyclic core structures of the antitumour agents amphidinolide N (1) and caribenolide I (2) has been developed, and the total synthesis of iso-epoxy-amphidinolide N and des-epoxy-caribenolide I structures is described. Central to the revised strategy was the use of a Horner-Wadsworth-Emmons olefination between beta-ketophosphonate 51 and aldehyde 14 to construct the C1-C13 sector common to both 1 and 2. Stereoselective alkylation of hydrazone 11 with iodide 65 and then with bromide 56 allowed for the rapid assembly of the complete caribenolide I carbon skeleton. Key steps in the completion of the synthesis of des-epoxy-caribenolide I structure 78 included hydrolysis of a sensitive methyl ester using Me(3)SnOH, followed by regioselective macrolactonisation of the resulting diol seco-acid and global deprotection. Coupling of hydrazone 11, bromide 56 and iodide 64 was followed by an analogous sequence of late-stage manoeuvres to arrive at the fully deprotected des-epoxy-amphidinolide N framework, obtained as a mixture of hemiacetal and bicyclic acetal 84. Regio- and diastereo-selective epoxidation of the C6 methylene group in bicyclic acetal 84 provided access to iso-epoxy-amphidinolide N stereoisomer 89.

  19. Concise Total Synthesis of (+)-Asperazine, (+)-Pestalazine A, and (+)-iso-Pestalazine A. Structure Revision of (+)-Pestalazine A

    PubMed Central

    Loach, Richard P.; Fenton, Owen S.; Movassaghi, Mohammad

    2016-01-01

    The concise, enantioselective total syntheses of (+)-asperazine (1), (+)-iso-pestalazine A (2), and (+)-pestalazine A (3) have been achieved by the development of a late-stage C3–C8′ Friedel-Crafts union of polycyclic diketopiperazines. Our modular strategy enables the union of complex polycyclic diketopiperazines in virtually their final forms, thus providing rapid and highly convergent assembly at the challenging quaternary stereocenter of these dimeric alkaloids. The significance of this carbon–carbon bond formation can be gauged by the manifold constraints that were efficiently overcome, namely the substantial steric crowding at both reactive sites, the nucleophilic addition of C8′ over N1′ to the C3 carbocation, and the multitude of reactivity posed by the use of complex diketopiperazine fragments in the coupling event. The success of the indoline π-nucleophile that evolved through our studies is notable given the paucity of competing reaction pathways observed in the presence of the highly reactive C3 carbocation generated. This first total synthesis of (+)-pestalazine A also allowed us to revise the molecular structure for this natural alkaloid. PMID:26726924

  20. Total synthesis and structural revision of TMG-chitotriomycin, a specific inhibitor of insect and fungal beta-N-acetylglucosaminidases.

    PubMed

    Yang, You; Li, Yao; Yu, Biao

    2009-09-02

    TMG-chitotriomycin, a potent and selective inhibitor of the beta-N-acetylglucosaminidases that possesses an unique N,N,N-trimethyl-d-glucosamine (TMG) residue, is revised to be the TMG-beta-(1-->4)-chitotriose instead of the originally proposed alpha-anomer via its total synthesis, for which a highly convergent approach was developed in which the sterically demanding (1-->4)-glycosidic linkages are efficiently constructed by the Au(I)-catalyzed glycosylation protocol with glycosyl o-hexynylbenzoates as donors.

  1. Asymmetric total synthesis and stereochemical revision of gymnangiamide.

    PubMed

    Tone, Hitoshi; Buchotte, Marie; Mordant, Céline; Guittet, Eric; Ayad, Tahar; Ratovelomanana-Vidal, Virginie

    2009-05-07

    The asymmetric total synthesis of the originally proposed structure of gymnangiamide, a cytotoxic pentapeptide isolated from the marine hydroid Gymnangium regae Jaderholm, has been achieved. Key to the synthesis was the use of asymmetric hydrogenation of alpha-substituted beta-ketoesters through dynamic kinetic resolution for the preparation of nonproteinogenic chiral amino acids. The disparity of the NMR spectra between the synthetic material containing the L-serine residue and the natural product required a revision of the proposed structure.

  2. The revised solar array synthesis computer program

    NASA Technical Reports Server (NTRS)

    1970-01-01

    The Revised Solar Array Synthesis Computer Program is described. It is a general-purpose program which computes solar array output characteristics while accounting for the effects of temperature, incidence angle, charged-particle irradiation, and other degradation effects on various solar array configurations in either circular or elliptical orbits. Array configurations may consist of up to 75 solar cell panels arranged in any series-parallel combination not exceeding three series-connected panels in a parallel string and no more than 25 parallel strings in an array. Up to 100 separate solar array current-voltage characteristics, corresponding to 100 equal-time increments during the sunlight illuminated portion of an orbit or any 100 user-specified combinations of incidence angle and temperature, can be computed and printed out during one complete computer execution. Individual panel incidence angles may be computed and printed out at the user's option.

  3. Short synthesis of 3-(hydroxymethyl)xylitol and structure revision of the anti-diabetic natural product from Casearia esculenta.

    PubMed

    Wang, Ruomeng; Paddon-Row, Michael N; Sherburn, Michael S

    2013-11-01

    3-(Hydroxymethyl)xylitol, a compound reportedly isolated from the root of Casearia esculenta (Roxb.), along with its three possible stereoisomers, has been synthesized for the first time by way of a triple dihydroxylation reaction performed upon the simplest cross-conjugated hydrocarbon, [3]dendralene. The data for the natural product do not match any of the isomeric 3-(hydroxymethyl)pentitols. The structure of the natural product from the root of Casearia esculenta (Roxb.) has been corrected by reanalysis of the published data.

  4. Total synthesis and revision of C6 stereochemistry of (+)-amphidinolide W.

    PubMed

    Ghosh, Arun K; Gong, Gangli

    2006-02-03

    An enantioselective first total synthesis and structural revision of the cytotoxic natural product amphidinolide W is described. We initially investigated a ring-closing metathesis based synthetic strategy to form the 12-membered macrocycle. This strategy was unsuccessful as it led to formation of a 17-membered macrocycle. Subsequently, we explored an alternative strategy that involved cross-metathesis followed by a Yamaguchi macrolactonization reaction sequence utilizing the same key intermediates. This strategy led to the synthesis of amphidinolide W. The synthesis was carried out in a convergent manner, and four of the five stereogenic centers in amphidinolide W were set by asymmetric synthesis. The synthesis features Sharpless asymmetric dihydroxylation, diastereoselective alkylation, efficient cross-metathesis of functionalized substrates, and novel functional group transformations using selective lipase-catalyzed hydrolysis of the primary acetate group. Of particular note, the C6 absolute stereochemistry of amphidinolide W has now been revised through our synthesis.

  5. Misassigned natural products and their revised structures.

    PubMed

    Yoo, Hye-Dong; Nam, Sang-Jip; Chin, Young-Won; Kim, Min-Sun

    2016-02-01

    Natural products are a major pipeline for drug development and are responsible for more than 50 % of drugs on the market. NMR is a fundamental and powerful tool for the structure determination of natural products. It is essential to provide unambiguous chemical structure information on natural products in drug development research, including the structure-activity relationship, derivatization and pharmacokinetic/pharmacodynamic studies. Advancement of NMR instruments has made it possible to deal with nanomole-scale natural products for structure elucidation, but misinterpretation of NMR spectra still occurs. We review 21 natural products with revised chemical structures and the methods used for those revisions.

  6. Programing Structural Synthesis System

    NASA Technical Reports Server (NTRS)

    Rogers, James L., Jr.

    1986-01-01

    Program aids research in analysis and optimization. Programing Structural Synthesis System (PROSSS2) developed to provide structural-synthesis capability by combining access to SPAR with CONMIN program and set of interface procedures. SPAR is large general-purpose finite-element structural-analysis program, and CONMIN is large general-purpose optimization program. PROSSS2 written in FORTRAN IV for batch execution.

  7. Stereochemistry of N-Benzoyl-5-substituted-1-benzazepines Revisited: Synthesis of the Conformationally Biased Derivatives and Revision of the Reported Structure.

    PubMed

    Tabata, Hidetsugu; Yoneda, Tetsuya; Tasaka, Tomohiko; Ito, Shigekazu; Oshitari, Tetsuta; Takahashi, Hideyo; Natsugari, Hideaki

    2016-04-15

    The syn (aR*,5R*) and anti (aS*,5R*) diastereomers of N-benzoyl-C5-substituted-1-benzazepines originating in the chiralities at C5 and the Ar-N(C═O) axis were first stereoselectively synthesized by biasing the conformation with a substituent at C6 and C9, respectively. Detailed examination of the stereochemistry (i.e., conformation and configuration) of these N-benzoyl-1-benzazepines by X-ray crystallographic analysis, VT NMR, and DFT calculations revealed new physicochemical aspects of these heterocycles including revision of the stereochemistry previously reported.

  8. Structural revision of two flavanonol glycosides from Smilax glabra.

    PubMed

    Zhou, Xiang; Xu, Qiang; Li, Jian-Xin; Chen, Ting

    2009-05-01

    The structures of two flavanonol glycosides isolated from Smilax glabra, named smitilbin and neosmitilbin, have been revised to isoastilbin and neoastilbin, respectively. The revised structures were determined based on intensive studies of chemical interconversion, NMR spectroscopy, and X-ray crystallographic analysis. The latest NMR data were also summarized.

  9. A Unified Strategy for Enantioselective Total Synthesis of Cladiellin and Briarellin Diterpenes: Total Synthesis of Briarellins E and F, and the Putative Structure of Alcyonin and Revision of Its Structure Assignment

    PubMed Central

    Corminboeuf, Olivier; Overman, Larry E.; Pennington, Lewis D.

    2009-01-01

    Enantioselective total syntheses of briarellin E (12) and briarellin F (13), as well as the structure originally proposed for the cladiellin diterpene alcyonin (10), have been realized. Comparison of the spectral data for synthetic 10, natural alcyonin, cladiellisin (33), and cladiellaperoxide (34), as well as chemical transformations of 10 and natural alcyonin, suggest that the structure of this coral metabolite is allylic peroxide 11. The unified approach detailed herein can be used to access both C4-deoxygenated and C4-oxygenated cladiellins and briarellins. The central step in these syntheses is acid-promoted condensation of (Z)-α,β-unsaturated aldehydes 17 with cyclohexadienyl diols 18, to form intermediates 16 incorporating the hexahydroisobenzofuran core and five stereocenters of these marine diterpenes (Scheme 1). PMID:19534538

  10. Synthesis of Inorganic Materials, 2nd, Revised and Updated Edition

    NASA Astrophysics Data System (ADS)

    Schubert, Ulrich; Hüsing, Nicola

    2005-02-01

    This second edition of a very well received advanced textbook retains the chemist's viewpoint in its comprehensive overview of methods for chemical synthesis of inorganic materials. The second chapter now includes a section on biomorphic ceramics, while one on LEDs has been added to Chapter 3. Chapter 4 now includes a more thorough explanation of borate glasses, with certain sections being completely rearranged. In addition, Chapter 6 has been extensively revised, and a whole new sub-chapter added on coordination polymers. The general principles and requirements are discussed for each method given, along with selected examples of technically applied materials, as well as the material properties and applications of the resulting products. Furthermore, numerous tables with further examples help in assessing the scope and limitation of the various methods and in choosing a suitable synthesis for any given problem. Intended for both courses in inorganic chemistry and materials science, this volume is equally valuable for all researchers working on the borderline of these two disciplines.

  11. Fostering revision of argumentative writing through structured peer assessment.

    PubMed

    Tsai, Ya-Chin; Chuang, Min-Tun

    2013-02-01

    This quasi-experimental study investigated the effect of structured peer assessment on revision of an argumentative writing. Two intact classes (N = 22, 26) were randomly assigned to be the trained and control groups. The latter received no facilitative resources, while the former participated in structured peer assessment based on Calibrated Peer Review, a web-based program purposefully designed for students to receive peer-assessment training, assess their peers' writing, and make written commentary online. At the end of the treatment, both groups revised their writing. The trained group revised their writing more extensively, outperforming the control group on frequency and type of revision, as well as the holistic quality of argumentative writing. After structured peer assessment, participants of the trained group became critical of their own work and invested more effort in spontaneous revision to produce higher-quality argumentative writing.

  12. Control Augmented Structural Synthesis

    NASA Technical Reports Server (NTRS)

    Lust, Robert V.; Schmit, Lucien A.

    1988-01-01

    A methodology for control augmented structural synthesis is proposed for a class of structures which can be modeled as an assemblage of frame and/or truss elements. It is assumed that both the plant (structure) and the active control system dynamics can be adequately represented with a linear model. The structural sizing variables, active control system feedback gains and nonstructural lumped masses are treated simultaneously as independent design variables. Design constraints are imposed on static and dynamic displacements, static stresses, actuator forces and natural frequencies to ensure acceptable system behavior. Multiple static and dynamic loading conditions are considered. Side constraints imposed on the design variables protect against the generation of unrealizable designs. While the proposed approach is fundamentally more general, here the methodology is developed and demonstrated for the case where: (1) the dynamic loading is harmonic and thus the steady state response is of primary interest; (2) direct output feedback is used for the control system model; and (3) the actuators and sensors are collocated.

  13. Structure A, architectural sections & details. Drawing no. H2, revised ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Structure A, architectural sections & details. Drawing no. H2, revised as-built dated October 11, 1951. Original drawing by Black & Veatch, consulting engineers, Kansas City, Missouri, prepared for the U.S. Department of the Army, Office of Engineers, Military Construction Division, Washington, D.C. dated October 1. - Travis Air Force Base, Building No. 925, W Street, Fairfield, Solano County, CA

  14. 78 FR 19541 - Proposed Revision to Design of Structures, Components, Equipment and Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-01

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Proposed Revision to Design of Structures, Components, Equipment and Systems AGENCY: Nuclear... comments on the proposed revisions in Chapter 3, ``Design of Structures, Components, Equipment, and...

  15. Revising.

    ERIC Educational Resources Information Center

    Wyman, Linda, Ed.

    1983-01-01

    In focusing on recursive writing, the nine articles in this journal issue suggest that student writing should be taken seriously. The first article states that revision should occur throughout the writing process while the second discusses how to invite writers to become active readers of their own texts. The third article presents methods of…

  16. Metallacyclopentadienes: synthesis, structure and reactivity.

    PubMed

    Ma, Wangyang; Yu, Chao; Chen, Tianyang; Xu, Ling; Zhang, Wen-Xiong; Xi, Zhenfeng

    2017-02-20

    Metallacyclopentadienes, which possess two M-C(sp(2)) bonds and feature the structure of M(C[upper bond 1 start]R(1)[double bond, length as m-dash]CR(2)-CR(3)[double bond, length as m-dash]C[upper bond 1 end]R(4)), are an important class of five-membered metallacycles. They are considered as both reactive intermediates in the stoichiometric and catalytic transformations of organic molecules and useful precursors to main group element compounds, and have received considerable attention in organometallic chemistry, coordination chemistry and synthetic organic chemistry over the past six decades because of their unique metallacyclic structure. This review comprehensively presents the synthesis, structure and reactivity of the s-, p-, d- and f-block metallacyclopentadienes distributed in the whole periodic table. In addition, their application in synthetic organic chemistry and polymer chemistry is summarized. This review aims to be beneficial for the design and synthesis of novel metallacyclopentadienes, and for promoting the rapid development of metallacyclic chemistry.

  17. Coibacins A and B: Total Synthesis and Stereochemical Revision

    PubMed Central

    Carneiro, Vânia M. T.; Avila, Carolina M.; Balunas, Marcy J.; Gerwick, William H.; Pilli, Ronaldo A.

    2014-01-01

    The interface between synthetic organic chemistry and natural products was explored in order to unravel the structure of coibacin A, a metabolite isolated from the marine cyanobacterium cf. Oscillatoria sp. that exhibits selective antileishmanial activity and potent anti-inflammatory properties. Our synthetic plan focused on a convergent strategy that allows rapid access to the desired target by coupling of three key fragments involving E-selective Wittig and modified Julia olefinations. CD measurements and comparative HPLC analyses between the natural product and four synthetic stereoisomers led to determination of its absolute configuration thus correcting the original assignment at C-5 and unambiguously establishing those at C-16 and C-18. Additionally, we have synthesized coibacin B based on the assignment of configuration for coibacin A. PMID:24359482

  18. Structural revision of some recently published iridoid glucosides.

    PubMed

    Jensen, Søren R; Caliş, Ihsan; Gotfredsen, Charlotte H; Søtofte, Inger

    2007-01-01

    The structures of six different iridoid glucosides have been revised. Three compounds isolated from Eremostachys glabra and designated 6,9-epi-8-O-acetylshanziside (1), 5,9-epi-penstemoside (2), and 5,9-epi-7,8-didehydropenstemoside (3) have been shown to be identical to the known iridoids barlerin (4, 8-O-acetylshanziside), penstemoside (5), and 7,8-didehydropenstemoside (6), respectively. Another compound named harpagoside-B, isolated from Scrophularia deserti and proposed to be 9-epi-6-O-methylharpagoside (11), was demonstrated from the spectroscopic data given to be the known harpagoside (10b). Finally, two alleged iridoid galactosides from Buddleja crispa named buddlejosides A and B (12a and 12b) have been shown to be the corresponding glucosides; the former is identical to agnuside (13a), while the latter is 3,4-dihydroxybenzoylaucubin (13b), an iridoid glucoside not previously published. This clearly showed that care should be taken with the interpretation of NOEs involving bridgehead protons in iridoid structures because they can be capricious and lead to erroneous structural assignments.

  19. Factor Structure of the Revised Anticipated Task-Orientation Scale.

    ERIC Educational Resources Information Center

    Jurma, William E.

    1981-01-01

    Responses to the revised version of the Anticipated Task-Orientation (ATO) Scale of 261 undergraduates were factor analyzed. Items associated with communication performance and motivation were similar to those in the original ATO instrument. Items composing the self-confidence factor were loaded on the communication performance factor in the…

  20. Confirming the Revised C-Terminal Domain of the MscL Crystal Structure

    PubMed Central

    Maurer, Joshua A.; Elmore, Donald E.; Clayton, Daniel; Xiong, Li; Lester, Henry A.; Dougherty, Dennis A.

    2008-01-01

    The structure of the C-terminal domain of the mechanosensitive channel of large conductance (MscL) has generated significant controversy. As a result, several structures have been proposed for this region: the original crystal structure (1MSL) of the Mycobacterium tuberculosis homolog (Tb), a model of the Escherichia coli homolog, and, most recently, a revised crystal structure of Tb-MscL (2OAR). To understand which of these structures represents a physiological conformation, we measured the impact of mutations to the C-terminal domain on the thermal stability of Tb-MscL using circular dichroism and performed molecular dynamics simulations of the original and the revised crystal structures of Tb-MscL. Our results imply that this region is helical and adopts an α-helical bundle conformation similar to that observed in the E. coli MscL model and the revised Tb-MscL crystal structure. PMID:18326638

  1. Approximation concepts for efficient structural synthesis

    NASA Technical Reports Server (NTRS)

    Schmit, L. A., Jr.; Miura, H.

    1976-01-01

    It is shown that efficient structural synthesis capabilities can be created by using approximation concepts to mesh finite element structural analysis methods with nonlinear mathematical programming techniques. The history of the application of mathematical programming techniques to structural design optimization problems is reviewed. Several rather general approximation concepts are described along with the technical foundations of the ACCESS 1 computer program, which implements several approximation concepts. A substantial collection of structural design problems involving truss and idealized wing structures is presented. It is concluded that since the basic ideas employed in creating the ACCESS 1 program are rather general, its successful development supports the contention that the introduction of approximation concepts will lead to the emergence of a new generation of practical and efficient, large scale, structural synthesis capabilities in which finite element analysis methods and mathematical programming algorithms will play a central role.

  2. 78 FR 48727 - Proposed Revisions to Design of Structures, Components, Equipment and Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... Core Support Structures.'' DATES: Comments must be filed no later than September 9, 2013. Comments... COMMISSION Proposed Revisions to Design of Structures, Components, Equipment and Systems AGENCY: Nuclear... Chapter 3, ``Design of Structures, Components, Equipment, and Systems'' and soliciting public comment...

  3. Synthesis and structures of metal chalcogenide precursors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.

    1990-01-01

    The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

  4. Eudistomidin G, a new beta-carboline alkaloid from the Okinawan marine tunicate Eudistoma glaucus and structure revision of eudistomidin B.

    PubMed

    Takahashi, Yohei; Ishiyama, Haruaki; Kubota, Takaaki; Kobayashi, Jun'ichi

    2010-07-15

    A new beta-carboline alkaloid, eudistomidin G (1), has been isolated from the Okinawan marine tunicate Eudistoma glaucus, and the structure was elucidated from spectroscopic data. Furthermore, the structure of eudistomidin B (2), which has been isolated from the same tunicate, was revised from 2a to 2b by detailed analyses of spectroscopic data. Asymmetric synthesis of the revised structure (2b) of eudistomidin B (2) and its (1S,10S)-diastereomer (2c) has been accomplished with the Noyori catalytic asymmetric hydrogen-transfer reaction. The absolute configuration of eudistomidin B (2) was confirmed to be 2b possessing (1R,10S)-configuration, from comparison of the (1)H NMR data, CD spectra, [alpha](D) values, and HPLC analysis of 2b, 2c, and natural eudistomidin B.

  5. 78 FR 15755 - Proposed Revision to Design of Structures, Components, Equipment and Systems; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-12

    ... COMMISSION Proposed Revision to Design of Structures, Components, Equipment and Systems; Correction AGENCY... Chapter 3, ``Design of Structures, Components, Equipment, and Systems'' and is soliciting public comment on NUREG-0800, ``Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power...

  6. Group psychology and the structural theory: a revised psychoanalytic model of group psychology.

    PubMed

    Saravay, S M

    1975-01-01

    It has been my aim in this paper to revise the existing psychoanalytic theory of group psychology in accordance with current structural concepts. The need for fundamental revision in the existing theory of group organization is demonstrated by its restriction to an oedipal paradigm, which cannot account for the regression to an oral paradigm of group organization during group formation. Freud's explanation of regression in crowds is reviewed. The limitations inherent in Freud's topographic and narcisistic models are demonstrated; irreconcilable contradictions are shown to exist between the two theories. A structural model of group psychology that is free from internal contradictions and provides a unifying explanation for both regression and merging in the crowd is developed. As a consequence of these revisions it is possible to conceptualize preoedipal organizations of group structure in addition to the oedipal paradigm proposed by Freud.

  7. Starch Synthesis in Arabidopsis. Granule Synthesis, Composition, and Structure1

    PubMed Central

    Zeeman, Samuel C.; Tiessen, Axel; Pilling, Emma; Kato, K. Lisa; Donald, Athene M.; Smith, Alison M.

    2002-01-01

    The aim of this work was to characterize starch synthesis, composition, and granule structure in Arabidopsis leaves. First, the potential role of starch-degrading enzymes during starch accumulation was investigated. To discover whether simultaneous synthesis and degradation of starch occurred during net accumulation, starch was labeled by supplying 14CO2 to intact, photosynthesizing plants. Release of this label from starch was monitored during a chase period in air, using different light intensities to vary the net rate of starch synthesis. No release of label was detected unless there was net degradation of starch during the chase. Similar experiments were performed on a mutant line (dbe1) that accumulates the soluble polysaccharide, phytoglycogen. Label was not released from phytoglycogen during the chase indicating that, even when in a soluble form, glucan is not appreciably degraded during accumulation. Second, the effect on starch composition of growth conditions and mutations causing starch accumulation was studied. An increase in starch content correlated with an increased amylose content of the starch and with an increase in the ratio of granule-bound starch synthase to soluble starch synthase activity. Third, the structural organization and morphology of Arabidopsis starch granules was studied. The starch granules were birefringent, indicating a radial organization of the polymers, and x-ray scatter analyses revealed that granules contained alternating crystalline and amorphous lamellae with a periodicity of 9 nm. Granules from the wild type and the high-starch mutant sex1 were flattened and discoid, whereas those of the high-starch mutant sex4 were larger and more rounded. These larger granules contained “growth rings” with a periodicity of 200 to 300 nm. We conclude that leaf starch is synthesized without appreciable turnover and comprises similar polymers and contains similar levels of molecular organization to storage starches, making Arabidopsis

  8. Starch synthesis in Arabidopsis. Granule synthesis, composition, and structure.

    PubMed

    Zeeman, Samuel C; Tiessen, Axel; Pilling, Emma; Kato, K Lisa; Donald, Athene M; Smith, Alison M

    2002-06-01

    The aim of this work was to characterize starch synthesis, composition, and granule structure in Arabidopsis leaves. First, the potential role of starch-degrading enzymes during starch accumulation was investigated. To discover whether simultaneous synthesis and degradation of starch occurred during net accumulation, starch was labeled by supplying (14)CO(2) to intact, photosynthesizing plants. Release of this label from starch was monitored during a chase period in air, using different light intensities to vary the net rate of starch synthesis. No release of label was detected unless there was net degradation of starch during the chase. Similar experiments were performed on a mutant line (dbe1) that accumulates the soluble polysaccharide, phytoglycogen. Label was not released from phytoglycogen during the chase indicating that, even when in a soluble form, glucan is not appreciably degraded during accumulation. Second, the effect on starch composition of growth conditions and mutations causing starch accumulation was studied. An increase in starch content correlated with an increased amylose content of the starch and with an increase in the ratio of granule-bound starch synthase to soluble starch synthase activity. Third, the structural organization and morphology of Arabidopsis starch granules was studied. The starch granules were birefringent, indicating a radial organization of the polymers, and x-ray scatter analyses revealed that granules contained alternating crystalline and amorphous lamellae with a periodicity of 9 nm. Granules from the wild type and the high-starch mutant sex1 were flattened and discoid, whereas those of the high-starch mutant sex4 were larger and more rounded. These larger granules contained "growth rings" with a periodicity of 200 to 300 nm. We conclude that leaf starch is synthesized without appreciable turnover and comprises similar polymers and contains similar levels of molecular organization to storage starches, making Arabidopsis

  9. Structural synthesis: Precursor and catalyst

    NASA Technical Reports Server (NTRS)

    Schmit, L. A.

    1984-01-01

    More than twenty five years have elapsed since it was recognized that a rather general class of structural design optimization tasks could be properly posed as an inequality constrained minimization problem. It is suggested that, independent of primary discipline area, it will be useful to think about: (1) posing design problems in terms of an objective function and inequality constraints; (2) generating design oriented approximate analysis methods (giving special attention to behavior sensitivity analysis); (3) distinguishing between decisions that lead to an analysis model and those that lead to a design model; (4) finding ways to generate a sequence of approximate design optimization problems that capture the essential characteristics of the primary problem, while still having an explicit algebraic form that is matched to one or more of the established optimization algorithms; (5) examining the potential of optimum design sensitivity analysis to facilitate quantitative trade-off studies as well as participation in multilevel design activities. It should be kept in mind that multilevel methods are inherently well suited to a parallel mode of operation in computer terms or to a division of labor between task groups in organizational terms. Based on structural experience with multilevel methods general guidelines are suggested.

  10. Application of the Crystalline Sponge Method to Revise the Structure of the Phenalenone Fuliginone.

    PubMed

    Brkljača, Robert; Schneider, Bernd; Hidalgo, William; Otálvaro, Felipe; Ospina, Felipe; Lee, Shoukou; Hoshino, Manabu; Fujita, Makoto; Urban, Sylvia

    2017-01-30

    The structure of fuliginone was revised from a phenyl substituted phenalenone to a hydroxyl substituted phenalenone as a result of its re-purification via HPLC with subsequent NMR analysis together with an independent synthesis and analysis of the crystal structure, which was secured via the crystalline sponge method. On-flow High Performance Liquid Chromatography coupled to Nuclear Magnetic Resonance spectroscopy (HPLC-NMR) was employed to confirm the presence of the natural product in the plant extract and to monitor for any possible degradation or conversion of the compound.

  11. Structural shape optimization in multidisciplinary system synthesis

    NASA Technical Reports Server (NTRS)

    Sobieszczanski-Sobieski, Jaroslaw

    1988-01-01

    Structural shape optimization couples with other discipline optimization in the design of complex engineering systems. For instance, the wing structural weight and elastic deformations couple to aerodynamic loads and aircraft performance through drag. This coupling makes structural shape optimization a subtask in the overall vehicle synthesis. Decomposition methods for optimization and sensitivity analysis allow the specialized disciplinary methods to be used while the disciplines are temporarily decoupled, after which the interdisciplinary couplings are restored at the system level. Application of decomposition methods to structures-aerodynamics coupling in aircraft is outlined and illustrated with a numerical example of a transport aircraft. It is concluded that these methods may integrate structural and aerodynamic shape optimizations with the unified objective of the maximum aircraft performance.

  12. Marine Nucleosides: Structure, Bioactivity, Synthesis and Biosynthesis

    PubMed Central

    Huang, Ri-Ming; Chen, Yin-Ning; Zeng, Ziyu; Gao, Cheng-Hai; Su, Xiangdong; Peng, Yan

    2014-01-01

    Nucleosides are glycosylamines that structurally form part of nucleotide molecules, the building block of DNA and RNA. Both nucleosides and nucleotides are vital components of all living cells and involved in several key biological processes. Some of these nucleosides have been obtained from a variety of marine resources. Because of the biological importance of these compounds, this review covers 68 marine originated nucleosides and their synthetic analogs published up to June 2014. The review will focus on the structures, bioactivities, synthesis and biosynthetic processes of these compounds. PMID:25474189

  13. Marine nucleosides: structure, bioactivity, synthesis and biosynthesis.

    PubMed

    Huang, Ri-Ming; Chen, Yin-Ning; Zeng, Ziyu; Gao, Cheng-Hai; Su, Xiangdong; Peng, Yan

    2014-12-02

    Nucleosides are glycosylamines that structurally form part of nucleotide molecules, the building block of DNA and RNA. Both nucleosides and nucleotides are vital components of all living cells and involved in several key biological processes. Some of these nucleosides have been obtained from a variety of marine resources. Because of the biological importance of these compounds, this review covers 68 marine originated nucleosides and their synthetic analogs published up to June 2014. The review will focus on the structures, bioactivities, synthesis and biosynthetic processes of these compounds.

  14. Factor Structure of the Revised TOEIC[R] Test: A Multiple-Sample Analysis

    ERIC Educational Resources Information Center

    In'nami, Yo; Koizumi, Rie

    2012-01-01

    This study examined the factor structure of the listening and reading sections of the revised Test of English for International Communication (TOEIC[R]) test. The data from the TOEIC IP (institutional program) test taken by 569 English learners were randomly split into two samples (n = 285 vs. 284). Four models (higher-order, correlated,…

  15. Factor Structure of Scores from the Conners' Rating Scales-Revised among Nepali Children

    ERIC Educational Resources Information Center

    Pendergast, Laura L.; Vandiver, Beverly J.; Schaefer, Barbara A.; Cole, Pamela M.; Murray-Kolb, Laura E.; Christian, Parul

    2014-01-01

    This study used exploratory and confirmatory factor analyses to examine the structures of scores from the Conners' Teacher and Parent Rating Scales-Revised (CTRS-R and CPRS-R, respectively; Conners, 1997). The scales were administered to 1,835 parents and 1,387 teachers of children in Nepal's Sarlahi district, a region where no other measures of…

  16. Factor Structure of Scores from the Conners' Rating Scales-Revised among Nepali Children

    ERIC Educational Resources Information Center

    Pendergast, Laura L.; Vandiver, Beverly J.; Schaefer, Barbara A.; Cole, Pamela M.; Murray-Kolb, Laura E.; Christian, Parul

    2014-01-01

    This study used exploratory and confirmatory factor analyses to examine the structures of scores from the Conners' Teacher and Parent Rating Scales-Revised (CTRS-R and CPRS-R, respectively; Conners, 1997). The scales were administered to 1,835 parents and 1,387 teachers of children in Nepal's Sarlahi district, a region where no other measures of…

  17. Structural, Item, and Test Generalizability of the Psychopathy Checklist-Revised to Offenders with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Morrissey, Catrin; Cooke, David; Michie, Christine; Hollin, Clive; Hogue, Todd; Lindsay, William R.; Taylor, John L.

    2010-01-01

    The Psychopathy Checklist-Revised (PCL-R) is the most widely used measure of psychopathy in forensic clinical practice, but the generalizability of the measure to offenders with intellectual disabilities (ID) has not been clearly established. This study examined the structural equivalence and scalar equivalence of the PCL-R in a sample of 185 male…

  18. Factor Structure of the Revised TOEIC[R] Test: A Multiple-Sample Analysis

    ERIC Educational Resources Information Center

    In'nami, Yo; Koizumi, Rie

    2012-01-01

    This study examined the factor structure of the listening and reading sections of the revised Test of English for International Communication (TOEIC[R]) test. The data from the TOEIC IP (institutional program) test taken by 569 English learners were randomly split into two samples (n = 285 vs. 284). Four models (higher-order, correlated,…

  19. Structural, Item, and Test Generalizability of the Psychopathy Checklist-Revised to Offenders with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Morrissey, Catrin; Cooke, David; Michie, Christine; Hollin, Clive; Hogue, Todd; Lindsay, William R.; Taylor, John L.

    2010-01-01

    The Psychopathy Checklist-Revised (PCL-R) is the most widely used measure of psychopathy in forensic clinical practice, but the generalizability of the measure to offenders with intellectual disabilities (ID) has not been clearly established. This study examined the structural equivalence and scalar equivalence of the PCL-R in a sample of 185 male…

  20. Improved approximations for control augmented structural synthesis

    NASA Technical Reports Server (NTRS)

    Thomas, H. L.; Schmit, L. A.

    1990-01-01

    A methodology for control-augmented structural synthesis is presented for structure-control systems which can be modeled as an assemblage of beam, truss, and nonstructural mass elements augmented by a noncollocated direct output feedback control system. Truss areas, beam cross sectional dimensions, nonstructural masses and rotary inertias, and controller position and velocity gains are treated simultaneously as design variables. The structural mass and a control-system performance index can be minimized simultaneously, with design constraints placed on static stresses and displacements, dynamic harmonic displacements and forces, structural frequencies, and closed-loop eigenvalues and damping ratios. Intermediate design-variable and response-quantity concepts are used to generate new approximations for displacements and actuator forces under harmonic dynamic loads and for system complex eigenvalues. This improves the overall efficiency of the procedure by reducing the number of complete analyses required for convergence. Numerical results which illustrate the effectiveness of the method are given.

  1. Improved approximations for control augmented structural synthesis

    NASA Technical Reports Server (NTRS)

    Thomas, H. L.; Schmit, L. A.

    1990-01-01

    A methodology for control-augmented structural synthesis is presented for structure-control systems which can be modeled as an assemblage of beam, truss, and nonstructural mass elements augmented by a noncollocated direct output feedback control system. Truss areas, beam cross sectional dimensions, nonstructural masses and rotary inertias, and controller position and velocity gains are treated simultaneously as design variables. The structural mass and a control-system performance index can be minimized simultaneously, with design constraints placed on static stresses and displacements, dynamic harmonic displacements and forces, structural frequencies, and closed-loop eigenvalues and damping ratios. Intermediate design-variable and response-quantity concepts are used to generate new approximations for displacements and actuator forces under harmonic dynamic loads and for system complex eigenvalues. This improves the overall efficiency of the procedure by reducing the number of complete analyses required for convergence. Numerical results which illustrate the effectiveness of the method are given.

  2. Computer applications for engineering/structural analysis. Revision 1

    SciTech Connect

    Zaslawsky, M.; Samaddar, S.K.

    1991-12-31

    Analysts and organizations have a tendency to lock themselves into specific codes with the obvious consequences of not addressing the real problem and thus reaching the wrong conclusion. This paper discusses the role of the analyst in selecting computer codes. The participation and support of a computation division in modifying the source program, configuration management, and pre- and post-processing of codes are among the subjects discussed. Specific examples illustrating the computer code selection process are described in the following problem areas: soil structure interaction, structural analysis of nuclear reactors, analysis of waste tanks where fluid structure interaction is important, analysis of equipment, structure-structure interaction, analysis of the operation of the superconductor supercollider which includes friction and transient temperature, and 3D analysis of the 10-meter telescope being built in Hawaii. Validation and verification of computer codes and their impact on the selection process are also discussed.

  3. Revised structure of the orthoborate YBO{sub 3}

    SciTech Connect

    Chadeyron, G.; El-Ghozzi, M.; Mahiou, R.; Arbus, A.; Cousseins, J.C.

    1997-02-01

    The YBO{sub 3} orthoborate was prepared by a flux evaporation process and the diffraction lines of its X-ray pattern were indexed on the basis of single crystal data. Crystal structure was determined (R = 0.035) in the P6{sub 3}/m space group from data recorded on a four-circle automatic diffractometer, with cell parameters a = 3.776 (1) {Angstrom}, c = 8.806 (4) {Angstrom}. The structure consists of a three-dimensional network made up of eightfold coordinated yttrium atoms and fourfold coordinated boron atoms. The structure exhibits two nonequivalent environments for the yttrium ions, which is confirmed by luminescence studies using the En{sup 3+} ion as structural probe. This work was completed by {sup 11}B NMR and IR studies, which show that boron has tetrahedral coordination.

  4. Chromene chalcones from Tephrosia carrollii and the revised structure of Oaracacin.

    PubMed

    Gómez-Garibay, F; Arciniega, M D; Céspedes, C L; Taboada, J; Calderón, J S

    2001-01-01

    The aerial parts of Tephrosia carrollii afforded two chromene chalcones. Their structures and stereochemistry were established by spectroscopic methods. The structure of oaxacacin was revised and confirmed by X-ray diffraction. In this paper, we describe the isolation of the chalcone known as "oaxacacin" and the new chalcone named epoxyobovatachalcone. The compound der. oaxacacin was found to be identical with obovatachalcone based on spectroscopic evidence and X-ray diffraction.

  5. Application of optimality criteria in structural synthesis

    NASA Technical Reports Server (NTRS)

    Terai, K.

    1974-01-01

    The rational use of optimality criteria was investigated for a class of structural synthesis problems where materials, configuration and applied load conditions are specified, and the minimum weight design is to be determined. The potential of hybrid methods of structural optimization for dealing with relatively large design problems involving practical complexity was explored. The reduced basis concept in design space was used to decrease the number of generalized design variables dealt with by the mathematical programming algorithm. Optimality criteria methods for obtaining design vectors associated with displacement, system buckling and natural frequency constraints are presented. A stress ratio method was used to generate a basis design vector representing the stress constraints. The finite element displacement method was used as the basic structural analysis tool. Results for several examples of truss systems subject to stress, displacement and minimum size constraints are presented. An assessment of these results indicates the effectiveness of the hybrid method developed.

  6. Nanostructured lead sulfide: synthesis, structure and properties

    NASA Astrophysics Data System (ADS)

    Sadovnikov, S. I.; Gusev, A. I.; Rempel, A. A.

    2016-07-01

    The theoretical and experimental results of recent studies dealing with nanostructured lead sulfide are summarized and analyzed. The key methods for the synthesis of nanostructured lead sulfide are described. The crystal structure of PbS in nanopowders and nanofilms is discussed. The influence of the size of nanostructure elements on the optical and thermal properties of lead sulfide is considered. The dependence of the band gap of PbS on the nanoparticle (crystallite) size for powders and films is illustrated. The bibliography includes 222 references.

  7. Simulation of Aircraft Engine Blade-Out Structural Dynamics. Revised

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

    2001-01-01

    A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

  8. `Guanigma': the revised structure of biogenic anhydrous guanine

    NASA Astrophysics Data System (ADS)

    Hirsch, Anna; Gur, Dvir; Polishchuk, Iryna; Levy, Davide; Pokroy, Boaz; Cruz-Cabeza, Aurora J.; Addadi, Lia; Kronik, Leeor; Leiserowitz, Leslie

    Living organisms display a spectrum of colors, produced by pigmentation, structural coloration, or both. A relatively well-studied system, which produces colors via an array of alternating anhydrous guanine crystals and cytoplasm, is responsible for the metallic luster of many fish. The structure of biogenic anhydrous guanine was believed to be the same as that of the synthetic one - a monoclinic polymorph. Here we re-examine the structure of biogenic guanine, using experimental X-ray and electron diffraction (ED) data exposing troublesome inconsistencies - namely, a 'guanigma'. To address this, we sought alternative candidate polymorphs using symmetry and packing considerations, then used first principles calculations to determine whether the selected candidates could be energetically stable. We identified theoretically a different monoclinic polymorph, were able to synthesize it, and to confirm using X-ray diffraction that it is this polymorph that occurs in biogenic samples. However, the ED data were still not consistent with this polymorph, but rather with a theoretically generated orthorhombic polymorph. This apparent inconsistency was resolved by showing how the ED pattern could be affected by crystal structural faults composed of offset molecular layers.

  9. Revision of the Li13Si4 structure

    PubMed Central

    Zeilinger, Michael; Fässler, Thomas F.

    2013-01-01

    Besides Li17Si4, Li16.42Si4, and Li15Si4, another lithium-rich representative in the Li–Si system is the phase Li13Si4 (trideca­lithium tetra­silicide), the structure of which has been determined previously [Frank et al. (1975 ▶). Z. Naturforsch. Teil B, 30, 10–13]. A careful analysis of X-ray diffraction patterns of Li13Si4 revealed discrepancies between experimentally observed and calculated Bragg positions. Therefore, we redetermined the structure of Li13Si4 on the basis of single-crystal X-ray diffraction data. Compared to the previous structure report, decisive differences are (i) the introduction of a split position for one Li site [occupancy ratio 0.838 (7):0.162 (7)], (ii) the anisotropic refinement of atomic displacement parameters for all atoms, and (iii) a high accuracy of atom positions and unit-cell parameters. The asymmetric unit of Li13Si4 contains two Si and seven Li atoms. Except for one Li atom situated on a site with symmetry 2/m, all other atoms are on mirror planes. The structure consists of isolated Si atoms as well as Si–Si dumbbells surrounded by Li atoms. Each Si atom is either 12- or 13-coordinated. The isolated Si atoms are situated in the ab plane at z = 0 and are strictly separated from the Si–Si dumbbells at z = 0.5. PMID:24454148

  10. Total Synthesis, Stereochemical Revision, and Biological Reassessment of Mandelalide A: Chemical Mimicry of Intrafamily Relationships.

    PubMed

    Willwacher, Jens; Heggen, Berit; Wirtz, Conny; Thiel, Walter; Fürstner, Alois

    2015-07-13

    Mandelalide A and three congeners had recently been isolated as the supposedly highly cytotoxic principles of an ascidian collected off the South African coastline. Since these compounds are hardly available from the natural source, a concise synthesis route was developed, targeting structure 1 as the purported representation of mandelalide A. The sequence involves an iridium-catalyzed two-directional Krische allylation and a cobalt-catalyzed carbonylative epoxide opening as entry points for the preparation of the major building blocks. The final stages feature the first implementation of terminal acetylene metathesis into natural product total synthesis, which is remarkable in that this class of substrates had been beyond the reach of alkyne metathesis for decades. Synthetic 1, however, proved not to be identical with the natural product. In an attempt to clarify this issue, NMR spectra were simulated for 20 conceivable diastereomers by using DFT followed by DP4 analysis; however, this did not provide a reliable assignment either. The puzzle was ultimately solved by the preparation of three diastereomers, of which compound 6 proved identical with mandelalide A in all analytical and spectroscopic regards. As the entire "northern sector" about the tetrahydrofuran ring in 6 shows the opposite configuration of what had originally been assigned, it is highly likely that the stereostructures of the sister compounds mandelalides B-D must be corrected analogously; we propose that these natural products are accurately represented by structures 68-70. In an attempt to prove this reassignment, an entry into mandelalides C and D was sought by subjecting an advanced intermediate of the synthesis of 6 to a largely unprecedented intramolecular Morita-Baylis-Hillman reaction, which furnished the γ-lactone derivative 74 as a mixture of diastereomers. Whereas (24R)-74 was amenable to a hydroxyl-directed dihydroxylation by using OsO4 /TMEDA as the reagent, the sister

  11. DOING THERAPY: A POST-STRUCTURAL RE-VISION.

    PubMed

    de Shazer, S; Berg, I K

    1992-01-01

    The purpose of this essay is to develop a way to look at doing therapy based on (a) Wittgenstein's concept of "language game"; (b) the relationship between Wittgenstein's "private language" argument, language games, and constructivism; and (c) post-structural thinking about language, how therapy works within language, and how language works within therapy. Case material is used to illustrate the usefulness of this approach.

  12. Superheavy Elements -- Synthesis, Structure and Reaction Mechanism

    SciTech Connect

    Ackermann, Dieter

    2006-08-14

    The exciting results search for superheavy elements which have been achieved in the recent years have triggered a broad range of activities. Apart from experiments to attempt the synthesis of new elements, nuclear structure investigations in the transactinide region has become possibly for Z up to 108 or 110. Heavy element chemistry has successfully placed Hs in the periodic table and is no attacking element 112. The development of accelerators and experimental methods promises advances to enable the extension of these investigations in regions closer to the ''island of stability''. Mass measurements using ion traps and neutron rich unstable beam species for the systematic investigation of nuclear structure and reaction mechanisms for heavy neutron rich system are believed to complete the variety of tools in future.

  13. Betulin Phosphonates; Synthesis, Structure, and Cytotoxic Activity.

    PubMed

    Chrobak, Elwira; Bębenek, Ewa; Kadela-Tomanek, Monika; Latocha, Małgorzata; Jelsch, Christian; Wenger, Emmanuel; Boryczka, Stanisław

    2016-08-26

    Betulin derivatives are a widely studied group of compounds of natural origin due to their wide spectrum of biological activities. This paper describes new betulin derivatives, containing a phosphonate group. The allyl-vinyl isomerization and synthesis of acetylenic derivatives have been reported. Structural identification of products as E and Z isomers has been carried out using ¹H-, (13)C-, (31)P-NMR, and crystallographic analysis. The crystal structure in the orthorhombic space group and analysis of crystal packing contacts for 29-diethoxyphosphoryl-28-cyclopropylpropynoyloxy-lup-20E(29)-en-3β-ol 8a are reported. All new compounds were tested in vitro for their antiproliferative activity against human T47D (breast cancer), SNB-19 (glioblastoma), and C32 (melanoma) cell lines.

  14. Structure A, protective alarm installation details. Drawing no. H3709, revised ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Structure A, protective alarm installation details. Drawing no. H3-709, revised as-built dated August 28, 1952. Original drawing by Black & Veatch, consulting engineers, Kansas City, Missouri, prepared for the U.S. Department of the Army, Office of Engineers, Military Construction Division, Washington, D.C. dated October 1, 1951. - Travis Air Force Base, Building No. 925, W Street, Fairfield, Solano County, CA

  15. The regional structure of the Red Sea Rift revised

    NASA Astrophysics Data System (ADS)

    Augustin, Nico; van der Zwan, Froukje M.; Devey, Colin W.; Brandsdóttir, Bryndís

    2017-04-01

    The Red Sea Rift has, for decades, been considered a text book example of how young ocean basins form and mature. Nevertheless, most studies of submarine processes in the Red Sea were previously based on sparse data (mostly obtained between the late 1960's and 1980's) collected at very low resolution. This low resolution, combined with large gaps between individual datasets, required large interpolations when developing geological models. Thus, these models generally considered the Red Sea Rift a special case of young ocean basement formation, dividing it from North to South into three zones: a continental thinning zone, a "transition zone" and a fully developed spreading zone. All these zones are imagined, in most of the models, to be separated by large transform faults, potentially starting and ending on the African and Arabian continental shields. However, no consensus between models e.g. about the locations (or even the existence) of major faults, the nature of the transition zone or the extent of oceanic crust in the Red Sea Rift has been reached. Recently, high resolution bathymetry revealed detailed seafloor morphology as never seen before from the Red Sea, very comparable to other (ultra)slow spreading mid-ocean ridges such as the Gakkel Ridge, the Mid-Atlantic Ridge and SW-Indian Ridge, changing the overall picture of the Red Sea significantly. New discoveries about the extent, movement and physical properties of submarine salt deposits led to the Red Sea Rift being linked to the young Aptian-age South Atlantic. Extensive crosscutting transform faults are not evident in the modern bathymetry data, neither in teleseismic nor vertical gravity gradient data and comparisons to Gakkel Ridge and the SW-Indian Ridge suggest that the Red Sea is much simpler in terms of structural geology than was previously thought. Complicated tectonic models do not appear necessary and there appears to be large areas of oceanic crust under the Red Sea salt blankets. Based on

  16. Comparison of the original and revised structures of the Health Promotion Model in predicting construction workers' use of hearing protection.

    PubMed

    Ronis, David L; Hong, OiSaeng; Lusk, Sally L

    2006-02-01

    Pender's health promotion model (HPM) has been revised, including substantial changes in its structure. The purpose of this study was to compare the fit and predictive usefulness of the original and revised structures of the HPM as applied to the use of hearing protection devices by 703 construction workers. Structural equation modeling was used to evaluate the two alternative forms of the model. Both forms of the model fit well, with the revised structure having a better fit and explaining more of the variance in use of hearing protection (28% vs. 18%). Results support the revised structure of the health promotion model (HPM) over the original form, and indicate it may be useful in understanding and predicting use of hearing protection.

  17. Synthesis, Structure And Properties of Electrochemically Active Nanocomposites

    DTIC Science & Technology

    2003-05-01

    agents such as alkali metals (Li and Na), alkaline-earth, hydrazine , sodium borohydride (NaBH4) and even late transition metals such as Zn [44, 45... SYNTHESIS , STRUCTURE AND PROPERTIES OF ELECTROCHEMICALLY ACTIVE NANOCOMPOSITES IL-SEOK KIM Department of Materials...A 3. DATES COVERED - 4. TITLE AND SUBTITLE Synthesis , Structure And Properties Of Electrochemically Active Nanocomposites 5a. CONTRACT

  18. Robust fixed-structure controller synthesis

    NASA Astrophysics Data System (ADS)

    Corrado, Joseph Ralph

    2000-10-01

    The ability to develop an integrated control system design methodology for robust high performance controllers satisfying multiple design criteria and real world hardware constraints constitutes a challenging task. The increasingly stringent performance specifications required for controlling such systems necessitates a trade-off between controller complexity and robustness. The principle challenge of the minimal complexity robust control design is to arrive at a tractable control design formulation in spite of the extreme complexity of such systems. Hence, design of minimal complexity robust controllers for systems in the face of modeling errors has been a major preoccupation of system and control theorists and practitioners for the past several decades. Although the theory for designing linear output feedback controllers is quite mature, the actual solution of the design equations can be a daunting task. This becomes even more difficult if an optimal reduced-order controller is sought. In this dissertation, we develop a general fixed-structure control design framework that addresses the following paradigm: Minimize control law complexity subject to the achievement of a specified accuracy in the face of a specified level of uncertainty. The control law complexity is minimized by developing a decentralized static output feedback formulation for fixed-structure controller synthesis. The decentralized static output feedback formulation captures a large class of controller architectures within a common framework and allows a common numerical algorithm to be used for computational purposes.

  19. Examining the impact of gender on the factor structure of the Psychopathic Personality Inventory-Revised.

    PubMed

    Anestis, Joye C; Caron, Kelly M; Carbonell, Joyce L

    2011-09-01

    Research on the factor structure of psychopathy has yielded mixed results, supporting anywhere from one to three factors. Additionally, most of this research has used all-male samples, and the possibility of structural invariance across gender has not been examined. Using a mixed-gender sample of 360 undergraduates, the factor structure of the Psychopathic Personality Inventory-Revised was examined using confirmatory factor analysis and multiple group analysis. One-, two-, and three-factor models were tested and compared with each other. When males and females were combined, none of the three models provided adequate fit to the data. Multiple group analyses revealed partial invariance across gender for all three models. Model comparison criteria supported use of both the one- and two-factor models, taking into account variable factor structure across gender. The importance of considering structural differences based on biological sex when assessing psychopathic traits is discussed.

  20. A revised structure and hydrogen bonding system in cellulose II from a neutron fiber diffraction analysis

    SciTech Connect

    Langan, P.; Nishiyama, Y.; Chanzy, H.

    1999-11-03

    The crystal and molecular structure and hydrogen bonding system in cellulose II have been revised using new neutron diffraction data extending to 1.2 {angstrom} resolution collected from two highly crystalline fiber samples of mercerized flax. Mercerization was achieved in NaOH/H{sub 2}O for one sample and in NaOD/D{sub 2}O for the other, corresponding to the labile hydroxymethyl moieties being hydrogenated and deuterated, respectively. Fourier difference maps were calculated in which neutron difference amplitudes were combined with phases calculated from two revised X-ray models of cellulose II. The revised phasing models were determined by refinement against the X-ray data set of Kolpak and Blackwell, using the LALS methodology. Both models have two antiparallel chains organized in a P2{sub 1} space group and unit cell parameters: a = 8.01 {angstrom}, b = 9.04 {angstrom}, c = 10.36 {angstrom}, and {gamma} = 117.1{degree}. One has equivalent backbone conformations for both chains but different conformations for the hydroxymethyl moieties: gt for the origin chain and tg for the center chain. The second model based on the recent crystal structures of cellotetraose, has different conformations for the two chains but nearly equivalent conformations for the hydroxymethyl moieties. On the basis of the X-ray data alone, the models could not be differentiated. From the neutron Fourier difference maps, possible labile hydrogen atom positions were identified for each model and refined using LALS. The second model is significantly different from previous proposals based on the crystal structures of cellotetraose, MD simulations of cellulose II, and any potential hydrogen-bonding network in the structure of cellulose II determined in earlier X-ray fiber diffraction studies. The exact localization of the labile hydrogen atoms involved in this bonding, together with their donor and acceptor characteristics, is presented and discussed. This study provides, for the first time

  1. Chiral Peropyrene: Synthesis, Structure, and Properties.

    PubMed

    Yang, Wenlong; Longhi, Giovanna; Abbate, Sergio; Lucotti, Andrea; Tommasini, Matteo; Villani, Claudio; Catalano, Vincent J; Lykhin, Aleksandr O; Varganov, Sergey A; Chalifoux, Wesley A

    2017-09-20

    Herein we describe the synthesis, structure, and properties of chiral peropyrenes. Using p-terphenyl-2,2″,6,6″-tetrayne derivatives as precursors, chiral peropyrenes were formed after a 4-fold alkyne cyclization reaction promoted by triflic acid. Due to the repulsion of the two aryl substituents within the same bay region, the chiral peropyrene adopts a twisted backbone with an end-to-end twist angle of 28° that was unambiguously confirmed by X-ray crystallographic analysis. The chiral peropyrene products absorb and emit in the green region of the UV-visible spectrum. Circular dichroism spectroscopy shows strong Cotton effects (Δε = ±100 M(-1) cm(-1) at 300 nm). The Raman data shows the expected D-band along with a split G-band that is due to longitudinal and transversal G modes. This data corresponds well with the simulated Raman spectra of chiral peropyrenes. The chiral peropyrene products also display circularly polarized luminescence. The cyclization reaction mechanism and the enantiomeric composition of the peropyrene products are explained using DFT calculations. The inversion barrier for racemization was determined experimentally to be 29 kcal/mol and is supported by quantum mechanical calculations.

  2. Organoactinide chemistry: synthesis, structure, and solution dynamics

    SciTech Connect

    Brennan, J.G.

    1985-12-01

    This thesis considers three aspects of organoactinide chemistry. In chapter one, a bidentate phosphine ligand was used to kinetically stabilize complexes of the type Cp/sub 2/MX/sub 2/. Ligand redistribution processes are present throughout the synthetic work, as has often been observed in uranium cyclopentadienyl chemistry. The effects of covalent M-L bonding on the solution and solid state properties of U(III) coordination complexes are considered. In particular, the nature of the more subtle interaction between the metal and the neutral ligand are examined. Using relative basicity data obtained in solution, and solid state structural data (and supplemented by gas phase photoelectron measurements), it is demonstrated that the more electron rich U(III) centers engage in significant U ..-->.. L ..pi..-donation. Trivalent uranium is shown to be capable of acting either as a one- or two-electron reducing agent toward a wide variety of unsaturated organic and inorganic molecules, generating molecular classes unobtainable via traditional synthetic approaches, as well as offering an alternative synthetic approach to molecules accessible via metathesis reactions. Ligand redistribution processes are again observed, but given the information concerning ligand lability, this reactivity pattern is applied to the synthesis of pure materials inaccessible from redox chemistry. 214 refs., 33 figs., 10 tabs.

  3. Meroterpenoids with New Skeletons from Myrtus communis and Structure Revision of Myrtucommulone K.

    PubMed

    Liu, Chao; Ang, Song; Huang, Xiao-Jun; Tian, Hai-Yan; Deng, Yuan-Yuan; Zhang, Dong-Mei; Wang, Ying; Ye, Wen-Cai; Wang, Lei

    2016-08-19

    Five sesquiterpene-based meroterpenoids with three kinds of new skeletons [1, 2, 3, (+)-4, and (-)-4] were isolated from the leaves of Myrtus communis. Compound 1 featured a new carbon skeleton with an unprecedented octahydrospiro[bicyclo[7.2.0]undecane-2,2'-chromene] tetracyclic ring system, which possessed two preferred conformations detected by variable-temperature NMR spectroscopy experiments. In addition, the structure of reported myrtucommulone K was revised to be compound 3. The plausible biosynthetic pathways of these meroterpenoids and their cytotoxicities are discussed.

  4. Structural Ceramic Nanocomposites: A Review of Properties and Powders' Synthesis Methods.

    PubMed

    Palmero, Paola

    2015-04-28

    Ceramic nanocomposites are attracting growing interest, thanks to new processing methods enabling these materials to go from the research laboratory scale to the commercial level. Today, many different types of nanocomposite structures are proposed in the literature; however, to fully exploit their exceptional properties, a deep understanding of the materials' behavior across length scales is necessary. In fact, knowing how the nanoscale structure influences the bulk properties enables the design of increasingly performing composite materials. A further key point is the ability of tailoring the desired nanostructured features in the sintered composites, a challenging issue requiring a careful control of all stages of manufacturing, from powder synthesis to sintering. This review is divided into four parts. In the first, classification and general issues of nanostructured ceramics are reported. The second provides basic structure-property relations, highlighting the grain-size dependence of the materials properties. The third describes the role of nanocrystalline second-phases on the mechanical properties of ordinary grain sized ceramics. Finally, the fourth part revises the mainly used synthesis routes to produce nanocomposite ceramic powders, underlining when possible the critical role of the synthesis method on the control of microstructure and properties of the sintered ceramics.

  5. Synthesis of the reported structures for kealiinines B and C

    PubMed Central

    Gibbons, Joseph B.; Gligorich, Keith M.; Welm, Bryan E.

    2013-01-01

    Synthesis of the reported structures of kealiinines B and C have been executed. An intermolecular electrophile-induced cyclization of a pendant arene on an ene-guanidine affords the tetracyclic, oxidized naphthimidazole cores. PMID:22966873

  6. Total Synthesis and Complete Structural Assignment of Thiocillin I

    PubMed Central

    2011-01-01

    The total synthesis of the thiopeptide antibiotic, thiocillin I, is described. This work unequivocally defines the full structure (constitution and configuration) of the natural product as 1. PMID:21446660

  7. Halohydrins and polyols derived from antirrhinoside: structural revisions of muralioside and epimuralioside

    PubMed

    Franzyk; Jensen; Thale; Olsen

    1999-02-01

    Treatment of the iridoid glucoside antirrhinoside (1) with pyridinium chloride in dimethylformamide gave rise to the two possible trans-halohydrins, linarioside (4) and isolinarioside (5). Pyridinium bromide gave the two analogous bromohydrins. It is shown that the iridoid glucosides 8-epi-muralioside from Linaria arcusangeli and 7,8-epi-antirrhinoside from Linaria dalmatica are both identical with isolinarioside, and therefore, these names are redundant. The structure of muralioside isolated from Cymbalaria muralis is revised to that of its 8-epimer (8), while the structure of an isomeric, new iridoid glucoside from Paulownia tomentosa has been elucidated to be 7beta-hydroxyharpagide (3), the structure originally assigned to 8. In addition, 7alpha-hydroxyharpagide (2), the known product from the base-catalyzed hydrolytic opening of 1, has been isolated from Antirrhinum majus and thus shown to be a natural product.

  8. A BIFACTOR APPROACH TO MODELING THE STRUCTURE OF THE PSYCHOPATHY CHECKLIST-REVISED

    PubMed Central

    Patrick, Christopher J.; Hicks, Brian M.; Nichol, Penny E.; Krueger, Robert F.

    2008-01-01

    To date, models of the structure of psychopathy as assessed by the Psychopathy Checklist-Revised (PCL-R) have taken a higher-order approach in which the factors of the PCL-R are modeled as correlated elements of a higher-order psychopathy construct. Here, we propose an alternative structural model of the PCL-R, the bifactor model, which accounts for the covariance among PCL-R items in terms of a general factor reflecting the overlap across all items, and independent subfactors reflecting the unique coherency among particular groups of items. We present examples of how this alternative structural model can account for diverging associations between different subsets of PCL-R items and external criteria in the domains of personality and psychopathology, and we discuss implications of the bifactor model for future research on the conceptualization and assessment of psychopathy. PMID:17492917

  9. Structure and Mechanism Revision of a Catalyzed Cyclization of Benzaldehyde Bearing Alkyne-Nitrile.

    PubMed

    Šafář, Peter; Marchalín, Štefan; Šoral, Michal; Moncol, Ján; Daïch, Adam

    2017-09-06

    Pt(II)-catalyzed carbocyclization of benzaldehyde containing a keto-nitrile functionality resulted in the formation, respectively, of isochromenes and spiro-lactones instead of fused lactams and spiro-lactams as was previously reported. The reaction mechanism was proposed, and the products were identified by multidimensional NMR, IR, and X-ray analysis. The structure of these new products was also confirmed by their synthesis in an unambiguous manner using practical and short approaches.

  10. Structural Ceramic Nanocomposites: A Review of Properties and Powders’ Synthesis Methods

    PubMed Central

    Palmero, Paola

    2015-01-01

    Ceramic nanocomposites are attracting growing interest, thanks to new processing methods enabling these materials to go from the research laboratory scale to the commercial level. Today, many different types of nanocomposite structures are proposed in the literature; however, to fully exploit their exceptional properties, a deep understanding of the materials’ behavior across length scales is necessary. In fact, knowing how the nanoscale structure influences the bulk properties enables the design of increasingly performing composite materials. A further key point is the ability of tailoring the desired nanostructured features in the sintered composites, a challenging issue requiring a careful control of all stages of manufacturing, from powder synthesis to sintering. This review is divided into four parts. In the first, classification and general issues of nanostructured ceramics are reported. The second provides basic structure–property relations, highlighting the grain-size dependence of the materials properties. The third describes the role of nanocrystalline second-phases on the mechanical properties of ordinary grain sized ceramics. Finally, the fourth part revises the mainly used synthesis routes to produce nanocomposite ceramic powders, underlining when possible the critical role of the synthesis method on the control of microstructure and properties of the sintered ceramics. PMID:28347029

  11. Revised structures of avenacosides A and B and a new sulfated saponin from Avena sativa L.

    PubMed

    Pecio, Łukasz; Jędrejek, Dariusz; Masullo, Milena; Piacente, Sonia; Oleszek, Wiesław; Stochmal, Anna

    2012-11-01

    The revised structures of avenacosides A and B and a new sulfated steroidal saponin isolated from grains of Avena sativa L. were elucidated. Their structures and complete NMR assignments are based on 1D and 2D NMR studies and identified as nuatigenin 3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-glucopyranoside}-26-O-β-D-glucopyranoside (1), nuatigenin 3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-(1→4)]-β-D-glucopyranoside}-26-O-β-D-glucopyranoside (2), and nuatigenin 3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-6-O-sulfoglucopyranosyl-(1→4)]-β-D-glucopyranoside}-26-O-β-D-glucopyranoside (3). Copyright © 2012 John Wiley & Sons, Ltd.

  12. Revising the Child and Adolescent Perfectionism Scale: A Test of the Four-Factor Structure in a Chinese Sample

    ERIC Educational Resources Information Center

    Yang, Hongfei; Hong, Chaoqin; Tao, Xiaodan; Zhu, Lingyi

    2015-01-01

    This study examined the structure, reliability, and validity of the revised Chinese version of the Child and Adolescent Perfectionism Scale (N = 933). The results confirmed the four-factor structure of the Chinese version of the Child and Adolescent Perfectionism Scale. Implications, limitations, and suggestions for future research are provided.

  13. Revising the Child and Adolescent Perfectionism Scale: A Test of the Four-Factor Structure in a Chinese Sample

    ERIC Educational Resources Information Center

    Yang, Hongfei; Hong, Chaoqin; Tao, Xiaodan; Zhu, Lingyi

    2015-01-01

    This study examined the structure, reliability, and validity of the revised Chinese version of the Child and Adolescent Perfectionism Scale (N = 933). The results confirmed the four-factor structure of the Chinese version of the Child and Adolescent Perfectionism Scale. Implications, limitations, and suggestions for future research are provided.

  14. Dynamic analysis of large structures by modal synthesis techniques.

    NASA Technical Reports Server (NTRS)

    Hurty, W. C.; Hart, G. C.; Collins, J. D.

    1971-01-01

    Several criteria that may be used to evaluate the merits of some of the existing techniques for the dynamic analysis of large structures which involve division into substructures or components are examined. These techniques make use of component displacement modes to synthetize global systems of generalized coordinates and, for that reason, they have come to be known as modal synthesis or component mode methods. Two techniques have been found to be particularly useful - i.e., the modal synthesis method with fixed attachment modes, and the modal synthesis method with free attachment modes. These two methods are treated in detail, and general flow charts are presented for guidance in computer programming.

  15. Convergent Synthesis and Structural Confirmation of Phellodonin and Sarcodonin ε

    PubMed Central

    Usui, Ippei; Lin, David W.; Masuda, Takeshi

    2013-01-01

    The first synthesis of members of the sarcodonin family, phellodonin and sarcodonin ε, is reported herein. This verifies that the unprecedented and seemingly unstable N,N-dioxide-containing benzodioxazine framework can be constructed in the laboratory, and lends further support to the proposed structures. The key step in the synthesis involves a biomimetic hetero-Diels–Alder reaction between a pyrazine N-oxide and an ortho-quinone. PMID:23577748

  16. Factor structure of the Impact of Event Scale-Revised in two different Peruvian samples.

    PubMed

    Gargurevich, Rafael; Luyten, Patrick; Fils, Jean-Francois; Corveleyn, Jozef

    2009-01-01

    This article studied the factor structure of the Impact of Event Scale-Revised (IES-R) in two samples in Peru, i.e., a sample of survivors of a fire (N=174) and a university student sample (N=562). First, confirmatory factor analysis was used to compare nine different models of posttraumatic stress disorder symptoms as evaluated by the IES-R in both of the samples separately. The model with the best fit in both samples had four correlated factors, i.e., Intrusion, Avoidance, Hyperarousal and Sleep Disturbance. Second, the degree of factorial invariance of the IES-R was compared in both the samples using multiple group confirmatory factor analysis. The results showed almost no differences between both samples. Finally, the results supported the internal consistency, as well as the concurrent and convergent validity of the IES-R in Peru. (c) 2009 Wiley-Liss, Inc.

  17. Factor Structure of Scores from the Conners’ Rating Scales–Revised Among Nepali Children

    PubMed Central

    Pendergast, Laura L.; Vandiver, Beverly J.; Schaefer, Barbara A.; Cole, Pamela M.; Murray-Kolb, Laura M.; Christian, Parul

    2014-01-01

    This study used exploratory and confirmatory factor analyses to examine the structures of scores from the Conners’ Teacher and Parent Rating Scales–Revised (CTRS-R and CPRS-R, respectively; Conners, 1997). The scales were administered to 1,835 parents and 1,387 teachers of children in Nepal's Sarlahi district – a region where no other measures of child psychopathology have been studied. With a Nepali sample, the findings indicate that reduced two factor models for the Conners’ scales are superior to the models identified in the scale development research. The hyperactivity and inattention factors were comparable to what has been identified in prior research, while other factors (e.g., social problems) differed substantially. Implications for use of the Conners’ scales in Nepal and cross cultural issues in the assessment of ADHD symptoms are discussed. PMID:25574454

  18. Factor Structure of Scores from the Conners' Rating Scales-Revised Among Nepali Children.

    PubMed

    Pendergast, Laura L; Vandiver, Beverly J; Schaefer, Barbara A; Cole, Pamela M; Murray-Kolb, Laura M; Christian, Parul

    2014-10-01

    This study used exploratory and confirmatory factor analyses to examine the structures of scores from the Conners' Teacher and Parent Rating Scales-Revised (CTRS-R and CPRS-R, respectively; Conners, 1997). The scales were administered to 1,835 parents and 1,387 teachers of children in Nepal's Sarlahi district - a region where no other measures of child psychopathology have been studied. With a Nepali sample, the findings indicate that reduced two factor models for the Conners' scales are superior to the models identified in the scale development research. The hyperactivity and inattention factors were comparable to what has been identified in prior research, while other factors (e.g., social problems) differed substantially. Implications for use of the Conners' scales in Nepal and cross cultural issues in the assessment of ADHD symptoms are discussed.

  19. Spin waves and revised crystal structure of honeycomb iridate Na2IrO3.

    PubMed

    Choi, S K; Coldea, R; Kolmogorov, A N; Lancaster, T; Mazin, I I; Blundell, S J; Radaelli, P G; Singh, Yogesh; Gegenwart, P; Choi, K R; Cheong, S-W; Baker, P J; Stock, C; Taylor, J

    2012-03-23

    We report inelastic neutron scattering measurements on Na2IrO3, a candidate for the Kitaev spin model on the honeycomb lattice. We observe spin-wave excitations below 5 meV with a dispersion that can be accounted for by including substantial further-neighbor exchanges that stabilize zigzag magnetic order. The onset of long-range magnetic order below T(N)=15.3  K is confirmed via the observation of oscillations in zero-field muon-spin rotation experiments. Combining single-crystal diffraction and density functional calculations we propose a revised crystal structure model with significant departures from the ideal 90° Ir-O-Ir bonds required for dominant Kitaev exchange.

  20. Structure and properties of the precipitates formed from condensed solutions of the revised simulated body fluid.

    PubMed

    Dorozhkina, Elena I; Dorozhkin, Sergey V

    2003-11-01

    Precipitation experiments with aqueous solutions of the Kokubo's revised simulated body fluid (rSBF) equal to 2, 4, 8, and 12 times the ionic concentration of human blood plasma were performed. Instead of Hepes, solution pH was adjusted to the desired value of 7.40 +/- 0.02 by either bubbling of CO2 or addition of HCl. The experiments were performed in tightly closed plastic vessels kept at 37.0 +/- 0.2 degrees C for 72 h under permanent shaking. Afterward, the suspensions were filtrated, and the precipitates were collected and analyzed. The results revealed that increasing the concentration of rSBF resulted in great changes in both the structure and the chemical composition of the precipitates. Phosphate substitution for carbonate (although the amounts of calcium and magnesium remained unchanged) and crystallinity decreasing were the most important modifications found in the precipitates formed from the highly condensed solutions of rSBF.

  1. The Revised Identity Style Inventory: Factor Structure and Validity in Italian Speaking Students

    PubMed Central

    Monacis, Lucia; de Palo, Valeria; Sinatra, Maria; Berzonsky, Michael D.

    2016-01-01

    The purpose of this study was to evaluate the factor structure and convergent and discriminant validity of scores on an Italian translation of the Revised Identity Style Inventory (ISI-5) with samples of 237 adolescents (50 males, Mage = 18.04, SD = .86) and 268 university students (42 males, Mage = 22.71, SD = 3.70). Confirmatory Factor Analysis indicated that a three-factor solution provided a good fit, which was invariant across age and sex groups. The theoretically relationships between scores on the ISI and scores on measures of reasoning and identity processes, identity commitment, and social desirability were partially consistent, thus further studies are needed to give more evidence to the convergent and discriminant validity. PMID:27378980

  2. Hierarchically porous materials: synthesis strategies and structure design.

    PubMed

    Yang, Xiao-Yu; Chen, Li-Hua; Li, Yu; Rooke, Joanna Claire; Sanchez, Clément; Su, Bao-Lian

    2017-01-23

    Owing to their immense potential in energy conversion and storage, catalysis, photocatalysis, adsorption, separation and life science applications, significant interest has been devoted to the design and synthesis of hierarchically porous materials. The hierarchy of materials on porosity, structural, morphological, and component levels is key for high performance in all kinds of applications. Synthesis and applications of hierarchically structured porous materials have become a rapidly evolving field of current interest. A large series of synthesis methods have been developed. This review addresses recent advances made in studies of this topic. After identifying the advantages and problems of natural hierarchically porous materials, synthetic hierarchically porous materials are presented. The synthesis strategies used to prepare hierarchically porous materials are first introduced and the features of synthesis and the resulting structures are presented using a series of examples. These involve templating methods (surfactant templating, nanocasting, macroporous polymer templating, colloidal crystal templating and bioinspired process, i.e. biotemplating), conventional techniques (supercritical fluids, emulsion, freeze-drying, breath figures, selective leaching, phase separation, zeolitization process, and replication) and basic methods (sol-gel controlling and post-treatment), as well as self-formation phenomenon of porous hierarchy. A series of detailed examples are given to show methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro-micropores, micro-mesopores, micro-macropores, meso-mesopores, meso-macropores, multiple porosities: micro-meso-macropores and meso-meso-macropores). We hope that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information about the synthesis of new hierarchically porous materials and

  3. Synthesis and revision of groups within the Newark Supergroup, eastern North America

    USGS Publications Warehouse

    Weems, R.E.; Olsen, P.E.

    1997-01-01

    early Mesozoic rift basins requires revision of the stratigraphy of several basins to make formation boundaries match group boundaries.

  4. Structural, item, and test generalizability of the psychopathy checklist--revised to offenders with intellectual disabilities.

    PubMed

    Morrissey, Catrin; Cooke, David; Michie, Christine; Hollin, Clive; Hogue, Todd; Lindsay, William R; Taylor, John L

    2010-03-01

    The Psychopathy Checklist-Revised (PCL-R) is the most widely used measure of psychopathy in forensic clinical practice, but the generalizability of the measure to offenders with intellectual disabilities (ID) has not been clearly established. This study examined the structural equivalence and scalar equivalence of the PCL-R in a sample of 185 male offenders with ID in forensic mental health settings, as compared with a sample of 1,212 male prisoners without ID. Three models of the PCL-R's factor structure were evaluated with confirmatory factor analysis. The 3-factor hierarchical model of psychopathy was found to be a good fit to the ID PCL-R data, whereas neither the 4-factor model nor the traditional 2-factor model fitted. There were no cross-group differences in the factor structure, providing evidence of structural equivalence. However, item response theory analyses indicated metric differences in the ratings of psychopathy symptoms between the ID group and the comparison prisoner group. This finding has potential implications for the interpretation of PCL-R scores obtained with people with ID in forensic psychiatric settings.

  5. Synthesis, structure and reactivity of [15]-macrodilactones.

    PubMed

    Si, Debjani; Peczuh, Mark W

    2015-06-21

    A strategy for utilizing parameters such as the ring size, planar units and the connections between them, and the location of asymmetric centers has been applied to the design and synthesis of a new class of 15-membered macrocycles. The interplay between three planar units in combination with a hinge atom and a stereogenic center, introduces a planar chirality that defines the molecular topology of these [15]-macrodilactones.

  6. Simple structured model for alpha-amylase synthesis by Bacillus amyloliquefaciens.

    PubMed

    Ponzo, J H; Weigand, W A

    1991-11-01

    A predictive, simple, structured model describing the synthesis of alpha-amylase by Bacillus amyloliquefaciens was formulated. Three key intracellular processes were identified (i.e, translation, and excretion) along with two key intracellular components (i.e., mRNA and the intracellular form of the alpha-amylase enzyme). Nearly all the model parameters were estimated by means of performing independent experiments, primarily fed-batch experiments. The model was shown to predict transient system behavior in batch and in fed-batch operation with some limitation and minor model parameter revisions. Since a principal objective was to demonstrate that independent experimental parameter determination can be used to construct the predictive model, further fine-tuning of the parameters may be necessary before application for optimization and control purposes.

  7. Factor Structure of the Luria-Nebraska Neuropsychological Battery-Children's Revision with Learning-Disabled Children.

    ERIC Educational Resources Information Center

    Snow, Jeffrey; Hynd, George W.

    1985-01-01

    Examined the factor structure of the Luria-Nebraska Neuropsychological Battery-Children's Revision in a population of learning-disabled children (N=100). Factor analysis and varimax rotation revealed three factors: a language-general intellectual factor, a reading-written expression factor, and a sensory-motor factor. (Author/MCF)

  8. The Structural and Predictive Properties of the Psychopathy Checklist-Revised in Canadian Aboriginal and Non-Aboriginal Offenders

    ERIC Educational Resources Information Center

    Olver, Mark E.; Neumann, Craig S.; Wong, Stephen C. P.; Hare, Robert D.

    2013-01-01

    We examined the structural and predictive properties of the Psychopathy Checklist-Revised (PCL-R) in large samples of Canadian male Aboriginal and non-Aboriginal offenders. The PCL-R ratings were part of a risk assessment for criminal recidivism, with a mean follow-up of 26 months postrelease. Using multigroup confirmatory factor analysis, we were…

  9. The Structural and Predictive Properties of the Psychopathy Checklist-Revised in Canadian Aboriginal and Non-Aboriginal Offenders

    ERIC Educational Resources Information Center

    Olver, Mark E.; Neumann, Craig S.; Wong, Stephen C. P.; Hare, Robert D.

    2013-01-01

    We examined the structural and predictive properties of the Psychopathy Checklist-Revised (PCL-R) in large samples of Canadian male Aboriginal and non-Aboriginal offenders. The PCL-R ratings were part of a risk assessment for criminal recidivism, with a mean follow-up of 26 months postrelease. Using multigroup confirmatory factor analysis, we were…

  10. First synthesis and structural determination of a monomeric, unsolvated lithium amide, LiNH(2).

    PubMed

    Grotjahn, D B; Sheridan, P M; Al Jihad, I; Ziurys, L M

    2001-06-13

    Alkali metal amides typically aggregate in solution and the solid phase, and even in the gas phase. In addition, even in the few known monomeric structures, the coordination number of the alkali metal is raised by binding of Lewis-basic solvent molecules, with concomitant changes in structure. In contrast, the simplest lithium amide LiNH(2) has never been made in a monomeric form, even though its structure has been theoretically predicted several times. Here, the first experimental structural data for a monomeric, unsolvated lithium amide are determined using a combination of gas-phase synthesis and millimeter/submillimeter-wave spectroscopy. All data point to a planar structure for LiNH(2). The r(o) structure of LiNH(2) has a Li-N distance of 1.736(3) A, an N-H distance of 1.022(3) A, and a H-N-H angle of 106.9(1) degrees. These results are compared with theoretical predictions for LiNH(2), and experimental data for oligomeric, solid-phase samples, which could not resolve the question of whether LiNH(2) is planar or not. In addition, comparisons are made with revised gas-phase and solid-phase data and calculated structures of NaNH(2).

  11. Synthesis and structural study of N-isopropenylbenzimidazolone

    NASA Astrophysics Data System (ADS)

    Mondieig, D.; Negrier, Ph.; Leger, J. M.; Lakhrissi, L.; El Assyry, A.; Lakhrissi, B.; Essassi, E. M.; Benali, B.; Boucetta, A.

    2015-05-01

    The synthesis and the crystal structure of the N-isopropenylbenzimidazolone (C10H10N2O) are presented. The synthesis was performed by Meth-Cohen method by reaction of o-phenylenediamine with ethyl acetoacetate in refluxed xylene. The single crystal structure was determined at room temperature by means of X-rays diffraction. The crystal system is monoclinic, with space group C2/c and eight molecules per unit cell. The unit cell dimensions are: a = 15.978(1) Å, b = 6.100(2) Å, c = 18.222(2) Å, β = 90.16(1)° and V = 1776.0(6) Å3.

  12. Structure elucidation of capsular polysaccharides from Streptococcus pneumoniae serotype 33C, 33D, and revised structure of serotype 33B.

    PubMed

    Lin, Fiona L; Vinogradov, Evgeny; Deng, Chenghua; Zeller, Sandra; Phelan, Lynn; Green, Bruce A; Jansen, Kathrin U; Pavliak, Viliam

    2014-01-13

    We report herein the previously unknown structures of the pneumococcal capsular polysaccharides serotype 33C and 33D, and a revised structure of serotype 33B. The syntenic pair 33B/33D has nearly identical polysaccharide repeat units with the exception of one sugar residue (→2-α-Glcp in 33B and →2-α-Galp in 33D). Serotype 33C is structurally more similar to 33B/33D than 33A/33F, in that it also possesses a backbone ribitol-phosphate group and a →3-β-GalpNAc residue, both of which are absent in the repeat units of 33A/33F. Serotype 33C is notably different from all other serogroup 33 polysaccharides, as there is no →3-β-Glcp residue and the location of the O-acetylation of the →5-β-Galf residue (O-6) differs from the other serogroup 33 polysaccharides (O-2). This completes the structural assignments of polysaccharides within serogroup 33 and provides a framework for understanding the recognition of epitopes by serogroup 33 typing sera based on observed cross-reactivities reported in the literature. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Factor structure of the Schizophrenia Quality of Life Scale Revision 4 (SQLS-R4).

    PubMed

    Martin, Colin R; Allan, Richard

    2007-03-01

    The Schizophrenia Quality of Life Scale Revision 4 (SQLS-R4) appears to offer excellent potential as an easily administered and patient acceptable assessment and monitoring measure of quality of life (QoL). However, a principle psychometric criterion crucial to the use and validity of the instrument concerns the underlying factor structure. The SQLS-R4 comprises two sub-scales, these being cognition and vitality QoL and psychosocial feelings QoL. However, the factor structure of the SQLS-R4 has yet to be established in a patient group in the UK. Confirmatory factor analysis was conducted on the SQLS-R4 to determine its psychometric properties in 100 patients with a primary ICD-10 diagnosis of schizophrenia. Internal reliability of the SQLS-R4 cognition and vitality QoL and psychosocial feelings QoL sub-scales was found to be excellent. Consistent with the original validation of the SQLS-R4, two correlated factors comprising cognition and vitality QoL and psychosocial feelings QoL were observed to offer the best fit to the data. In conclusion, the SQLS-R4 would appear to be suitable for use in patients with a primary diagnosis of schizophrenia in the UK. Potential clinical uses and the direction of future research with the SQLS-R4 are indicated.

  14. Total synthesis of the proposed structure of astakolactin

    PubMed Central

    Mameda, Keisuke; Fujishiro, Moe; Yoshinaga, Yutaka

    2014-01-01

    Summary The first total synthesis of the proposed structure of astakolactin, a sesterterpene metabolite isolated from the marine sponge Cacospongia scalaris, has been achieved, mainly featuring Johnson–Claisen rearrangement, asymmetric Mukaiyama aldol reaction and MNBA-mediated lactonization. PMID:25383112

  15. Structural morphology of crystals with the barite (BaSO 4) structure: A revision and extension

    NASA Astrophysics Data System (ADS)

    Hartman, P.; Strom, C. S.

    1989-09-01

    The structural morphology of crystals with the barite (BaSO 4) structure (sulphates, chromates, perchlorates, permanganates and tetrafluoroborates) has been determined with the use of computer programs. Uniquely defined F forms are {002}, {210}, {211}, {020} and {201}. Two different F slices were found for {101} and {200}, 33 for {011}. Attachment energies and specific surface energies have been calculated for an electrostatic point charge model as a function of the charge distribution in the anion. On this basis it is concluded that {101} behaves as an F form, {200} as an S form and {011} as a K form. The theoretical growth form shows {210}, {101} and {002} as main forms. A comparison is made with habits of natural and synthetic crystals. Experiments on KCIO 4 show that {011} appears at high supersaturations (>38; ;20%). It is shown that a broken bond model provides relative attachment energies that are higher by a factor of about three.

  16. Spreading Effect in Industrial Complex Network Based on Revised Structural Holes Theory

    PubMed Central

    Ye, Qing; Guan, Jun

    2016-01-01

    This paper analyzed the spreading effect of industrial sectors with complex network model under perspective of econophysics. Input-output analysis, as an important research tool, focuses more on static analysis. However, the fundamental aim of industry analysis is to figure out how interaction between different industries makes impacts on economic development, which turns out to be a dynamic process. Thus, industrial complex network based on input-output tables from WIOD is proposed to be a bridge connecting accurate static quantitative analysis and comparable dynamic one. With application of revised structural holes theory, flow betweenness and random walk centrality were respectively chosen to evaluate industrial sectors’ long-term and short-term spreading effect process in this paper. It shows that industries with higher flow betweenness or random walk centrality would bring about more intensive industrial spreading effect to the industrial chains they stands in, because value stream transmission of industrial sectors depends on how many products or services it can get from the other ones, and they are regarded as brokers with bigger information superiority and more intermediate interests. PMID:27218468

  17. An Assessment of the Dimensionality and Factorial Structure of the Revised Paranormal Belief Scale

    PubMed Central

    Drinkwater, Kenneth; Denovan, Andrew; Dagnall, Neil; Parker, Andrew

    2017-01-01

    Since its introduction, the Revised Paranormal Belief Scale (RPBS) has developed into a principal measure of belief in the paranormal. Accordingly, the RPBS regularly appears within parapsychological research. Despite common usage, academic debates continue to focus on the factorial structure of the RPBS and its psychometric integrity. Using an aggregated heterogeneous sample (N = 3,764), the present study tested the fit of 10 factorial models encompassing variants of the most commonly proposed solutions (seven, five, two, and one-factor) plus new bifactor alternatives. A comparison of competing models revealed a seven-factor bifactor solution possessed superior data-model fit (CFI = 0.945, TLI = 0.933, IFI = 0.945, SRMR = 0.046, RMSEA = 0.058), containing strong factor loadings for a general factor and weaker, albeit acceptable, factor loadings for seven subfactors. This indicated that belief in the paranormal, as measured by the RPBS, is best characterized as a single overarching construct, comprising several related, but conceptually independent subfactors. Furthermore, women reported significantly higher paranormal belief scores than men, and tests of invariance indicated that mean differences in gender are unlikely to reflect measurement bias. Results indicate that despite concerns about the content and psychometric integrity of the RPBS the measure functions well at both a global and seven-factor level. Indeed, the original seven-factors contaminate alternative solutions. PMID:29018398

  18. [Clinical research. XIII. Research design contribution in the structured revision of an article].

    PubMed

    Talavera, Juan O; Rivas-Ruiz, Rodolfo

    2013-01-01

    The quality of information obtained in accordance to research design is integrated to the revision structured in relation to the causality model, used in the article "Reduction in the Incidence of Nosocomial Pneumonia Poststroke by Using the 'Turn-mob' Program", which corresponds to a clinical trial design. Points to identify and analyze are ethical issues in order to safeguard the security and respect for patients, randomization that seek to create basal homogeneous groups, subjects with the same probability of receiving any of the maneuvers in comparison, with the same pre maneuver probability of adherence, and which facilitate the blinding of outcome measurement and the distribution between groups of subjects with the same probability of leaving the study for reasons beyond the maneuvers. Other aspects are the relativity of comparison, the blinding of the maneuver, the parallel application of comparative maneuver, early stopping, and analysis according to the degree of adherence. The analysis in accordance with the design is complementary, since it is done based on the architectural model of causality, and the statistical and clinical relevance consideration.

  19. Spreading Effect in Industrial Complex Network Based on Revised Structural Holes Theory.

    PubMed

    Xing, Lizhi; Ye, Qing; Guan, Jun

    2016-01-01

    This paper analyzed the spreading effect of industrial sectors with complex network model under perspective of econophysics. Input-output analysis, as an important research tool, focuses more on static analysis. However, the fundamental aim of industry analysis is to figure out how interaction between different industries makes impacts on economic development, which turns out to be a dynamic process. Thus, industrial complex network based on input-output tables from WIOD is proposed to be a bridge connecting accurate static quantitative analysis and comparable dynamic one. With application of revised structural holes theory, flow betweenness and random walk centrality were respectively chosen to evaluate industrial sectors' long-term and short-term spreading effect process in this paper. It shows that industries with higher flow betweenness or random walk centrality would bring about more intensive industrial spreading effect to the industrial chains they stands in, because value stream transmission of industrial sectors depends on how many products or services it can get from the other ones, and they are regarded as brokers with bigger information superiority and more intermediate interests.

  20. Synthesis and structural characterization of zinc titanates

    NASA Astrophysics Data System (ADS)

    Akgül, Güvenç

    2013-04-01

    The aim of this study is to accurately obtain of local atomic structures of zinc titanates (ZnTiO3 and Zn2TiO4). Samples have been synthesized by the ball milling method using mixture of high purity ZnO and TiO2 powders. X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) techniques have been used to probe crystal and local structures of the synthesized powders. They have been found to exhibit very high crystallinity. In addition, the EXAFS results have showed that the ball milling is a quite effective method to fabricate highly crystalline nanosized powders. The obtained results are presented in detail.

  1. RNA synthesis and purification for structural studies.

    PubMed

    Ahmed, Yasar Luqman; Ficner, Ralf

    2014-01-01

    RNAs play pivotal roles in the cell, ranging from catalysis (e.g., RNase P), acting as adaptor molecule (tRNA) to regulation (e.g., riboswitches). Precise understanding of its three-dimensional structures has given unprecedented insight into the molecular basis for all of these processes. Nevertheless, structural studies on RNA are still limited by the very special nature of this polymer. The most common methods for the determination of 3D RNA structures are NMR and X-ray crystallography. Both methods have their own set of requirements and give different amounts of information about the target RNA. For structural studies, the major bottleneck is usually obtaining large amounts of highly pure and homogeneously folded RNA. Especially for X-ray crystallography it can be necessary to screen a large number of variants to obtain well-ordered single crystals. In this mini-review we give an overview about strategies for the design, in vitro production, and purification of RNA for structural studies.

  2. Synthesis and Structure of Perrhenate Sodalite

    SciTech Connect

    Mattigod, Shas V.; McGrail, B. PETER; McCready, David E.; Wang, Li Q.; Parker, Kent E.; Young, James S.

    2006-04-15

    Na8(AlSiO4)6(ReO4)2 sodalite was synthesized using a hydrothermal method, and its crystal structure was determined from Rietveld refinement of experimental X-ray powder diffraction data. The refinement showed that this compound adopts the cubic sodalite structure (Space Group, No.218) with a = 9.1528 (1) ?. Raman spectroscopic measurements confirm the presence of tetrahedral ReO4- groups. Broadening of the asymmetric stretching and bending vibrational modes suggests the tetrahedra are slightly distorted from ideal Td symmetry in the sodalite lattice. MAS NMR of 29Si and 27Al nuclei showed single intense peaks at ?iso = -92.4 ppm and ?iso = 57.5 ppm, respectively, confirming the alternating Si, Al tetrahedral ordering in sodalite deduced from the structural data. Chemical shifts for 29Si and 27Al calculated using correlative structural parameters (56.6 ? 0.8 ppm and -92.3 ? 0.9 ppm) showed good agreement with measured data indicating the validity of data derived from the Rietveld structural refinement.

  3. The Neo Personality Inventory-Revised: Factor Structure and Gender Invariance from Exploratory Structural Equation Modeling Analyses in a High-Stakes Setting

    ERIC Educational Resources Information Center

    Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas

    2013-01-01

    This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)…

  4. The Neo Personality Inventory-Revised: Factor Structure and Gender Invariance from Exploratory Structural Equation Modeling Analyses in a High-Stakes Setting

    ERIC Educational Resources Information Center

    Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas

    2013-01-01

    This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)…

  5. Specific accumulation and revised structures of acridone alkaloid glucosides in the tips of transformed roots of Ruta graveolens.

    PubMed

    Kuzovkina, Inna; Al'terman, Irina; Schneider, Bernd

    2004-04-01

    The root tips of Ruta graveolens (common rue) show strong autofluorescence of acridone alkaloids, which are characteristic secondary metabolites of this plant. To study the specific distribution and accumulation of acridone alkaloids in various root segments of Ruta graveolens, root material was harvested from genetically transformed root cultures and extracts were investigated by chromatographic techniques and HPLC-(1)H NMR spectroscopy. The cells of the elongation and differentiation zones contained acridone glucosides and large amounts of acridone alkaloids, mainly rutacridone. Gravacridondiol glucoside was identified as the dominant secondary compound of the root tips and its structure revised by means of spectroscopic methods. In addition, minor acridones, including the structurally revised gravacridontriol glucoside and unknown natural products, were found in the root tip.

  6. The Padua Inventory: Do Revisions Need Revision?

    ERIC Educational Resources Information Center

    Gonner, Sascha; Ecker, Willi; Leonhart, Rainer

    2010-01-01

    The purpose of the present study was to examine the psychometric properties, factorial structure, and validity of the Padua Inventory-Washington State University Revision and of the Padua Inventory-Revised in a large sample of patients with obsessive-compulsive disorder (n = 228) and with anxiety disorders and/or depression (n = 213). The…

  7. The Padua Inventory: Do Revisions Need Revision?

    ERIC Educational Resources Information Center

    Gonner, Sascha; Ecker, Willi; Leonhart, Rainer

    2010-01-01

    The purpose of the present study was to examine the psychometric properties, factorial structure, and validity of the Padua Inventory-Washington State University Revision and of the Padua Inventory-Revised in a large sample of patients with obsessive-compulsive disorder (n = 228) and with anxiety disorders and/or depression (n = 213). The…

  8. Analysis and Synthesis of Robust Data Structures

    DTIC Science & Technology

    1990-08-01

    1.3.2 Multiversion Software. .. .. .. .. .. .... .. ... .. ...... 5 1.3.3 Robust Data Structure .. .. .. .. .. .. .. .. .. ... .. ..... 6 1.4...context are 0 multiversion software, which is an adaptation oi N-modulo redundancy (NMR) tech- nique. * recovery blocks, which is an adaptation of...implementations using these features for such a hybrid approach. 1.3.2 Multiversion Software Avizienis [AC77] was the first to adapt NMR technique into

  9. Synthesis and Structure of Technetium Trichloride

    SciTech Connect

    Poineau, Frederic; Johnstone, Erik V.; Weck, Philippe F.; Kim, Eunja; Forster, Paul M.; Scott, Brian L.; Sattelberger, Alfred P.; Czerwinski, Kenneth R.

    2010-12-07

    Technetium trichloride has been synthesized by reaction of Tc{sub 2}(O{sub 2}CCH{sub 3}){sub 4}Cl{sub 2} with HCl(g) at 300 C. The mechanism of formation mimics the one described earlier in the literature for rhenium. Tc{sub 2}(O{sub 2}CCH{sub 3}){sub 2}Cl{sub 4} [P{sub T}; a = 6.0303(12) {angstrom}, b = 6.5098(13) {angstrom}, c = 8.3072(16) {angstrom}, {alpha} = 112.082(2){sup o}, {beta} = 96.667(3){sup o}, {gamma} = 108.792(3){sup o}; Tc-Tc = 2.150(1) {angstrom}] is formed as an intermediate in the reaction at 100 C. Technetium trichloride is formed above 250 C and is isostructural with its rhenium homologue. The structure consists of Tc{sub 3}Cl{sub 9} clusters [R{sub 3}m; a = b = 10.1035(19) {angstrom}, c = 20.120(8) {angstrom}], and the Tc-Tc separation is 2.444(1) {angstrom}. Calculations on TcX{sub 3} (X = Cl, Br) have confirmed the stability of TcCl{sub 3} and suggest the existence of a polymorph of TcBr{sub 3} with the ReBr{sub 3} structure.

  10. Analysis and synthesis of textures by structural methods

    NASA Astrophysics Data System (ADS)

    Gutiérrez Vázquez, León M.; Kober, Vitaly

    2008-08-01

    The purpose of this work is to develop structural models for textures description. On the base of the models, algorithms for analysis of textures are proposed. The algorithms consist of a set of basic digital linear and nonlinear filters, which are used in cascade and parallel connections with possible feedback. The proposed methods and models are also used for synthesis of textures, which are similar to textures from the Brodatz's album. Computer simulation results are provided and discussed.

  11. Synthesis of the putative structure of 15-oxopuupehenoic acid.

    PubMed

    Boulifa, Ettahir; Fernández, Antonio; Alvarez, Esteban; Alvarez-Manzaneda, Ramón; Mansour, Ahmed I; Chahboun, Rachid; Alvarez-Manzaneda, Enrique

    2014-11-07

    Synthesis of the putative structure of the marine natural 15-oxopuupehenoic acid has been achieved starting from commercial (-)-sclareol. Key steps of the synthetic sequence are the Robinson annulation of a β-ketoester and methyl vinyl ketone and an unprecedented cyclization of the resulting α,β-enone, which is mediated by tin(IV) chloride in the presence of N-phenylselenophthalimide. The physical properties of the synthetic compound are somewhat different from those reported for the natural product.

  12. An implementation of the distributed programming structural synthesis system (PROSSS)

    NASA Technical Reports Server (NTRS)

    Rogers, J. L., Jr.

    1981-01-01

    A method is described for implementing a flexible software system that combines large, complex programs with small, user-supplied, problem-dependent programs and that distributes their execution between a mainframe and a minicomputer. The Programming Structural Synthesis System (PROSSS) was the specific software system considered. The results of such distributed implementation are flexibility of the optimization procedure organization and versatility of the formulation of constraints and design variables.

  13. A new approximation method for stress constraints in structural synthesis

    NASA Technical Reports Server (NTRS)

    Vanderplaats, Garret N.; Salajegheh, Eysa

    1987-01-01

    A new approximation method for dealing with stress constraints in structural synthesis is presented. The finite element nodal forces are approximated and these are used to create an explicit, but often nonlinear, approximation to the original problem. The principal motivation is to create the best approximation possible, in order to reduce the number of detailed finite element analyses needed to reach the optimum. Examples are offered and compared with published results, to demonstrate the efficiency and reliability of the proposed method.

  14. Synthesis and Structure of a Novel Bis-Stibole

    DTIC Science & Technology

    1994-10-18

    are thermochromic . 3 in this account, we report the synthesis and solid state structure of some unusual bis- stibolobenzene dervatives. We have... material through the column. The solvent was removed In vacuo to leave a yellow solid (0.265 g, 0.434 mreol, 71%). This material was dissolved in...from the remaining material by fractional crystallization were unsuccessful. In a separate experiment, a mixture of 2a and 2b was crystallized from

  15. Tetrabromidocuprates(II)—Synthesis, Structure and EPR

    PubMed Central

    Zabel, André; Winter, Alette; Kelling, Alexandra; Schilde, Uwe; Strauch, Peter

    2016-01-01

    Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g‖ and g⊥) of the tensors could be determined and information on the structural changes in the [CuBr4]2− anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. PMID:27104522

  16. Robust penalty method for structural synthesis

    NASA Technical Reports Server (NTRS)

    Kamat, M. P.

    1983-01-01

    The Sequential Unconstrained Minimization Technique (SUMT) offers an easy way of solving nonlinearly constrained problems. However, this algorithm frequently suffers from the need to minimize an ill-conditioned penalty function. An ill-conditioned minimization problem can be solved very effectively by posing the problem as one of integrating a system of stiff differential equations utilizing concepts from singular perturbation theory. This paper evaluates the robustness and the reliability of such a singular perturbation based SUMT algorithm on two different problems of structural optimization of widely separated scales. The report concludes that whereas conventional SUMT can be bogged down by frequent ill-conditioning, especially in large scale problems, the singular perturbation SUMT has no such difficulty in converging to very accurate solutions.

  17. Curdlan ester derivatives: synthesis, structure, and properties.

    PubMed

    Marubayashi, Hironori; Yukinaka, Kazuyori; Enomoto-Rogers, Yukiko; Takemura, Akio; Iwata, Tadahisa

    2014-03-15

    A series of ester derivatives of curdlan, which is a β-(1 → 3)-D-glucan extracellularly produced by microorganism, with varying alkyl chain lengths (C2-C12) were synthesized by the heterogeneous reaction using trifluoroacetic anhydride. As a result, high-molecular-weight (Mw ≥ 6 × 10(5)) and fully-acylated curdlan was obtained with relatively high yield (>70%). Thermal stability of curdlan was greatly improved by esterification. Crystallization was observed for curdlan esters with C2-C6 side chains. Both Tg (170 → 50 °C) and Tm (290 → 170 °C) of curdlan esters decreased with increasing the side-chain length. By the increase in the side-chain carbon number, curdlan esters showed lower Young's modulus and tensile strength, and larger elongation at break. Thus, material properties of curdlan esters can be controlled by changing the side-chain length. It was found that the increase of the side-chain length resulted in the decrease of crystallinity and the change of crystal structures.

  18. Structure prediction and targeted synthesis: a new Na(n)N2 diazenide crystalline structure.

    PubMed

    Zhang, Xiuwen; Zunger, Alex; Trimarchi, Giancarlo

    2010-11-21

    Significant progress in theoretical and computational techniques for predicting stable crystal structures has recently begun to stimulate targeted synthesis of such predicted structures. Using a global space-group optimization (GSGO) approach that locates ground-state structures and stable stoichiometries from first-principles energy functionals by objectively starting from randomly selected lattice vectors and random atomic positions, we predict the first alkali diazenide compound Na(n)N(2), manifesting homopolar N-N bonds. The previously predicted Na(3)N structure manifests only heteropolar Na-N bonds and has positive formation enthalpy. It was calculated based on local Hartree-Fock relaxation of a fixed-structure type (Li(3)P-type) found by searching an electrostatic point-ion model. Synthesis attempts of this positive ΔH compound using activated nitrogen yielded another structure (anti-ReO(3)-type). The currently predicted (negative formation enthalpy) diazenide Na(2)N(2) completes the series of previously known BaN(2) and SrN(2) diazenides where the metal sublattice transfers charge into the empty N(2) Π(g) orbital. This points to a new class of alkali nitrides with fundamentally different bonding, i.e., homopolar rather than heteropolar bonds and, at the same time, illustrates some of the crucial subtleties and pitfalls involved in structure predictions versus planned synthesis. Attempts at synthesis of the stable Na(2)N(2) predicted here will be interesting.

  19. Structure, synthesis and biological properties of the pentacyclic guanidinium alkaloids.

    PubMed

    Shi, Yunlong; Moazami, Yasamin; Pierce, Joshua G

    2017-06-01

    The pentacyclic guanidinium alkaloids (PGAs) are a family of marine natural products that possess a polycyclic guanidine-containing core and a long alkyl chain tethered spermidine-derived tail that is rarely observed in other natural products. These natural products exhibit potent activities on a wide range of organisms and therefore have attracted the attention of many synthetic chemists; however, the structure-activity relationships and mechanisms of action of PGAs remain largely elusive. Herein we summarize the structure, synthesis, toxicity and mechanisms of action of PGAs and highlight their potential as chemical probes and/or therapeutic leads. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Optimal placement of active elements in control augmented structural synthesis

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Jin, I. M.; Schmit, L. A., Jr.

    1992-01-01

    A methodology for structural/control synthesis is presented in which the optimal location of active members is treated in terms of (0,1) variables. Structural member sizes, control gains and (0,1) placement variables are treated simultaneously as design variables. Optimization is carried out by generating and solving a sequence of explicit approximate problems using a branch and bound strategy. Intermediate design variable and intermediate response quantity concepts are used to enhance the quality of the approximate design problems. Numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.

  1. Synthesis of aircraft structures using integrated design and analysis methods

    NASA Technical Reports Server (NTRS)

    Sobieszczanski-Sobieski, J.; Goetz, R. C.

    1978-01-01

    A systematic research is reported to develop and validate methods for structural sizing of an airframe designed with the use of composite materials and active controls. This research program includes procedures for computing aeroelastic loads, static and dynamic aeroelasticity, analysis and synthesis of active controls, and optimization techniques. Development of the methods is concerned with the most effective ways of integrating and sequencing the procedures in order to generate structural sizing and the associated active control system, which is optimal with respect to a given merit function constrained by strength and aeroelasticity requirements.

  2. Ionothermal synthesis and crystal structures of metal phosphate chains

    SciTech Connect

    Wragg, David S.; Le Ouay, Benjamin; Beale, Andrew M.; O'Brien, Matthew G.; Slawin, Alexandra M.Z.; Warren, John E.; Prior, Timothy J.; Morris, Russell E.

    2010-07-15

    We have prepared isostructural aluminium and gallium phosphate chains by ionothermal reactions in 1-ethyl-3-methylimidazolium bromide and 1-ethylpyridinium bromide under a variety of conditions. The chains can be prepared as pure phases or along with three dimensional framework phases. The chains are favoured at shorter heating times and the crystallinity can be improved by addition of transition metal acetates and amines which are not included in the final structure. The chain can be prepared with or without the presence of hydrofluoric acid. - Graphical abstract: Chain structures prepared from ionic liquid solvents under a wide variety of synthesis conditions.

  3. Reduced complexity structural modeling for automated airframe synthesis

    NASA Technical Reports Server (NTRS)

    Hajela, Prabhat

    1987-01-01

    A procedure is developed for the optimum sizing of wing structures based on representing the built-up finite element assembly of the structure by equivalent beam models. The reduced-order beam models are computationally less demanding in an optimum design environment which dictates repetitive analysis of several trial designs. The design procedure is implemented in a computer program requiring geometry and loading information to create the wing finite element model and its equivalent beam model, and providing a rapid estimate of the optimum weight obtained from a fully stressed design approach applied to the beam. The synthesis procedure is demonstrated for representative conventional-cantilever and joined wing configurations.

  4. Measuring chronic condition self-management in an Australian community: factor structure of the revised Partners in Health (PIH) scale.

    PubMed

    Smith, David; Harvey, Peter; Lawn, Sharon; Harris, Melanie; Battersby, Malcolm

    2017-01-01

    To evaluate the factor structure of the revised Partners in Health (PIH) scale for measuring chronic condition self-management in a representative sample from the Australian community. A series of consultations between clinical groups underpinned the revision of the PIH. The factors in the revised instrument were proposed to be: knowledge of illness and treatment, patient-health professional partnership, recognition and management of symptoms and coping with chronic illness. Participants (N = 904) reporting having a chronic illness completed the revised 12-item scale. Two a priori models, the 4-factor and bi-factor models were then evaluated using Bayesian confirmatory factor analysis (BCFA). Final model selection was established on model complexity, posterior predictive p values and deviance information criterion. Both 4-factor and bi-factor BCFA models with small informative priors for cross-loadings provided an acceptable fit with the data. The 4-factor model was shown to provide a better and more parsimonious fit with the observed data in terms of substantive theory. McDonald's omega coefficients indicated that the reliability of subscale raw scores was mostly in the acceptable range. The findings showed that the PIH scale is a relevant and structurally valid instrument for measuring chronic condition self-management in an Australian community. The PIH scale may help health professionals to introduce the concept of self-management to their patients and provide assessment of areas of self-management. A limitation is the narrow range of validated PIH measurement properties to date. Further research is needed to evaluate other important properties such as test-retest reliability, responsiveness over time and content validity.

  5. Confirming the Structural Validity of the My Class Inventory -- Short Form Revised

    ERIC Educational Resources Information Center

    Mariani, Melissa; Villares, Elizabeth; Sink, Christopher A.; Colvin, Kimberly; Kuba, Summer Perhay

    2015-01-01

    Researchers analyzed data collected from elementary school students (N = 893) to further establish the psychometric soundness of the My Class Inventory--Short Form Revised (MCI-SFR). A confirmatory factor analysis was conducted resulting in a good fit for a four-factor model, which corresponds to the instrument's four scales (Cohesion,…

  6. The Structure of the Autism Diagnostic Interview-Revised: Diagnostic and Phenotypic Implications

    ERIC Educational Resources Information Center

    Snow, Anne V.; Lecavalier, Luc; Houts, Carrie

    2009-01-01

    Background: Multivariate statistics can assist in refining the nosology and diagnosis of pervasive developmental disorders (PDD) and also contribute important information for genetic studies. The Autism Diagnostic Interview-Revised (ADI-R) is one of the most widely used assessment instruments in the field of PDD. The current study investigated its…

  7. The Structure of the Autism Diagnostic Interview-Revised: Diagnostic and Phenotypic Implications

    ERIC Educational Resources Information Center

    Snow, Anne V.; Lecavalier, Luc; Houts, Carrie

    2009-01-01

    Background: Multivariate statistics can assist in refining the nosology and diagnosis of pervasive developmental disorders (PDD) and also contribute important information for genetic studies. The Autism Diagnostic Interview-Revised (ADI-R) is one of the most widely used assessment instruments in the field of PDD. The current study investigated its…

  8. Confirming the Structural Validity of the My Class Inventory -- Short Form Revised

    ERIC Educational Resources Information Center

    Mariani, Melissa; Villares, Elizabeth; Sink, Christopher A.; Colvin, Kimberly; Kuba, Summer Perhay

    2015-01-01

    Researchers analyzed data collected from elementary school students (N = 893) to further establish the psychometric soundness of the My Class Inventory--Short Form Revised (MCI-SFR). A confirmatory factor analysis was conducted resulting in a good fit for a four-factor model, which corresponds to the instrument's four scales (Cohesion,…

  9. Precision synthesis, structure and function of helical polymers

    PubMed Central

    OKAMOTO, Yoshio

    2015-01-01

    Helical structures are chiral, which means that if we can synthesize a polymer having a stable one-handed helicity, the polymer is optically active. In 1979, we succeeded in the synthesis of a one-handed helical polymer from an optically inactive achiral monomer, triphenylmethyl methacrylate (TrMA). This is the first example of the asymmetric synthesis of an optically active one-handed helical polymer. The polymer (PTrMA) exhibited an unexpected high chiral recognition ability and afforded a practically useful chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) by coating it on silica gel. In addition, we also succeeded in the development of very useful CSPs for HPLC using the phenylcarbamate derivatives of polysaccharides, cellulose and amylose. These CSPs can efficiently resolve a broad range of chiral compounds, and have been used all over the world for separating and analyzing chiral compounds. PMID:26062738

  10. Total Synthesis and Evaluation of Phostriecin and Key Structural Analogues

    PubMed Central

    Burke, Christopher P.; Swingle, Mark R.; Honkanen, Richard E.; Boger, Dale L.

    2010-01-01

    Full details of the total synthesis of phostriecin (2), the assignment of its relative and absolute stereochemistry, and the resultant structural reassignment of the natural product previously represented as sultriecin (1), a phosphate versus sulfate monoester, are detailed. Studies with authentic material confirmed that phostriecin, but not sultriecin, is an effective and selective inhibitor of protein phosphatase 2A (PP2A) defining a mechanism of action responsible for its antitumor activity. The extension of the studies to the synthesis and evaluation of a series of key synthetic analogues is disclosed that highlights the importance of the natural product phosphate monoester (vs sulfate or free alcohol, inactive and >250-fold), the α,β-unsaturated lactone (12-fold), and the hydrophobic Z,Z,E-triene tail (C12–C22, ca. 200-fold) including the unique importance of its unsaturation (50-fold, and no longer PP2A selective). PMID:20669916

  11. Precision synthesis, structure and function of helical polymers.

    PubMed

    Okamoto, Yoshio

    2015-01-01

    Helical structures are chiral, which means that if we can synthesize a polymer having a stable one-handed helicity, the polymer is optically active. In 1979, we succeeded in the synthesis of a one-handed helical polymer from an optically inactive achiral monomer, triphenylmethyl methacrylate (TrMA). This is the first example of the asymmetric synthesis of an optically active one-handed helical polymer. The polymer (PTrMA) exhibited an unexpected high chiral recognition ability and afforded a practically useful chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) by coating it on silica gel. In addition, we also succeeded in the development of very useful CSPs for HPLC using the phenylcarbamate derivatives of polysaccharides, cellulose and amylose. These CSPs can efficiently resolve a broad range of chiral compounds, and have been used all over the world for separating and analyzing chiral compounds.

  12. Alphavirus RNA synthesis and non-structural protein functions.

    PubMed

    Rupp, Jonathan C; Sokoloski, Kevin J; Gebhart, Natasha N; Hardy, Richard W

    2015-09-01

    The members of the genus Alphavirus are positive-sense RNA viruses, which are predominantly transmitted to vertebrates by a mosquito vector. Alphavirus disease in humans can be severely debilitating, and depending on the particular viral species, infection may result in encephalitis and possibly death. In recent years, alphaviruses have received significant attention from public health authorities as a consequence of the dramatic emergence of chikungunya virus in the Indian Ocean islands and the Caribbean. Currently, no safe, approved or effective vaccine or antiviral intervention exists for human alphavirus infection. The molecular biology of alphavirus RNA synthesis has been well studied in a few species of the genus and represents a general target for antiviral drug development. This review describes what is currently understood about the regulation of alphavirus RNA synthesis, the roles of the viral non-structural proteins in this process and the functions of cis-acting RNA elements in replication, and points to open questions within the field.

  13. Reconciling icetexane biosynthetic connections with their chemical synthesis: total synthesis of (+/-)-5,6-dihydro-6alpha-hydroxysalviasperanol, (+/-)-brussonol, and (+/-)-abrotanone.

    PubMed

    Simmons, Eric M; Yen, Jennifer R; Sarpong, Richmond

    2007-07-05

    A unified strategy for the chemical synthesis of the icetexane diterpenoids brussonol and 5,6-dihydro-6alpha-hydroxysalviasperanol has led to a structural revision of the recently isolated natural products abrotandiol and abrotanone.

  14. Revised Atomistic Models of the Crystal Structure of C-S-H with high C/S Ratio

    NASA Astrophysics Data System (ADS)

    Kovačević, Goran; Nicoleau, Luc; Nonat, André; Veryazov, Valera

    2016-09-01

    The atomic structure of calcium-silicate-hydrate (C1.67-S-Hx) has been studied. Atomistic C-S-H models suggested in our previous study have been revised in order to perform a direct comparison of energetic stability of the different structures. An extensive set of periodic structures of C-S-H with variation of water content was created, and then optimized using molecular dynamics with reactive force field ReaxFF and quantum chemical semiempirical method PM6. All models show organization of water molecules inside the structure of C-S-H. The new geometries of C-S-H, reported in this paper, show lower relative energy with respect to the geometries from the original definition of C-S-H models. Model that corresponds to calcium enriched tobermorite structure has the lowest relative energy and the density closest to the experimental values.

  15. Structural studies of myosin:nucleotide complexes: a revised model for the molecular basis of muscle contraction.

    PubMed Central

    Fisher, A J; Smith, C A; Thoden, J; Smith, R; Sutoh, K; Holden, H M; Rayment, I

    1995-01-01

    The structures of the MgADP-beryllium fluoride and MgADP-aluminum fluoride complexes of the truncated myosin head from Dictyostelium myosin II are reported. These reveal the location of the nucleotide complex and define the amino acid residues that form the active site. The tertiary structure of the beryllium fluoride complex is essentially identical to that seen previously in the three-dimensional structure of chicken skeletal muscle myosin. By contrast, significant domain movements are observed in the aluminum fluoride complex. These structural findings form the basis of a revised model for the structural basis of the contractile cycle. It is now suggested that the narrow cleft that splits the central 50-kDa segment of the heavy chain provides not only the communication route between the nucleotide-binding pocket and actin but also transmits the conformational change necessary for movement. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 PMID:7787065

  16. PASS: A computer program for Preliminary Aircraft Structural Synthesis

    NASA Technical Reports Server (NTRS)

    Johnson, E. H.

    1977-01-01

    A computer code for Preliminary Aircraft Structural Synthesis provides rapid and accurate analysis for aircraft structures that can be adequately modeled by beam finite elements. The philosophy used in developing the program was to provide a basic framework that can be used for structural synthesis. It is anticipated that a user will need to add detail to this framework in order to perform his specific task. With this philosophy in mind, the program was written so that it is easily divided into segments, thereby making it readily adaptable. The theoretical portion of this manual describes the basic structure of the program and details the development of the unique beam element that is used. The present capability of the algorithm is stated and suggestions are made regarding enhancements to this capability. User information is also given that provides an overview of the program's construction, identifies the required inputs, describes the program output, provides some comments on the program use, and exhibits results for a simple example.

  17. Application of the Probabilistic Dynamic Synthesis Method to Realistic Structures

    NASA Technical Reports Server (NTRS)

    Brown, Andrew M.; Ferri, Aldo A.

    1998-01-01

    The Probabilistic Dynamic Synthesis method is a technique for obtaining the statistics of a desired response engineering quantity for a structure with non-deterministic parameters. The method uses measured data from modal testing of the structure as the input random variables, rather than more "primitive" quantities like geometry or material variation. This modal information is much more comprehensive and easily measured than the "primitive" information. The probabilistic analysis is carried out using either response surface reliability methods or Monte Carlo simulation. In previous work, the feasibility of the PDS method applied to a simple seven degree-of-freedom spring-mass system was verified. In this paper, extensive issues involved with applying the method to a realistic three-substructure system are examined, and free and forced response analyses are performed. The results from using the method are promising, especially when the lack of alternatives for obtaining quantitative output for probabilistic structures is considered.

  18. Synthesis and structure of a carbohydrate-fused [15]-macrodilactone.

    PubMed

    Si, Debjani; Peczuh, Mark W

    2016-11-03

    The design, synthesis and structural characterization of a new α-d-glucose fused [15]-macrodilactone is reported. The macrolide was synthesized by a route involving sequential acylations of glucose at the C4' and C6' hydroxyl groups followed by an intramolecular Stille reaction previously established for other [15]-macrodilactones. Analysis of the X-ray crystallographic structure of the macrolide revealed a unique conformation of this macrocycle that differs from earlier models for [13]- and [15]-macrodilactones. Organizing the three planar units and the pyranose moiety into a macrocyclic ring resulted in a cup-shaped structure with planar chirality. Further, the gt conformation of the exocyclic hydroxymethyl group in the glucose unit was found to be crucial for controlling the planar chirality and, hence, governing the molecular shape and overall topology of the compound. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Neural network based decomposition in optimal structural synthesis

    NASA Technical Reports Server (NTRS)

    Hajela, P.; Berke, L.

    1992-01-01

    The present paper describes potential applications of neural networks in the multilevel decomposition based optimal design of structural systems. The generic structural optimization problem of interest, if handled as a single problem, results in a large dimensionality problem. Decomposition strategies allow for this problem to be represented by a set of smaller, decoupled problems, for which solutions may either be obtained with greater ease or may be obtained in parallel. Neural network models derived through supervised training, are used in two distinct modes in this work. The first uses neural networks to make available efficient analysis models for use in repetitive function evaluations as required by the optimization algorithm. In the second mode, neural networks are used to represent the coupling that exists between the decomposed subproblems. The approach is illustrated by application to the multilevel decomposition-based synthesis of representative truss and frame structures.

  20. A highly convergent synthesis of the C1-C31 polyol domain of amphidinol 3 featuring a TST-RCM reaction: confirmation of the revised relative stereochemistry.

    PubMed

    Grisin, Aleksandr; Evans, P Andrew

    2015-11-13

    The concise enantioselective synthesis of the revised C1-C31 fragment of the polyketide amphidinol 3 was accomplished in 16 steps and 12.8% overall yield. Salient features of the strategy include chemoselective Weinreb amide coupling and concomitant CBS reduction for the preparation of the C1-C15 tris-syn-1,5-diol motif and a temporary silicon-tethered ring-closing metathesis (TST-RCM) reaction in combination with a diastereoselective hydroboration for the construction of the C16-C31 polypropionate fragment. The union of the fragments was accomplished by a regioselective ring-opening of the terminal epoxide with a phenyl sulfone stabilized carbanion, which upon reduction and deprotection permits a comparison of the relative configuration with the natural product.

  1. The extended evolutionary synthesis: its structure, assumptions and predictions

    PubMed Central

    Laland, Kevin N.; Uller, Tobias; Feldman, Marcus W.; Sterelny, Kim; Müller, Gerd B.; Moczek, Armin; Jablonka, Eva; Odling-Smee, John

    2015-01-01

    Scientific activities take place within the structured sets of ideas and assumptions that define a field and its practices. The conceptual framework of evolutionary biology emerged with the Modern Synthesis in the early twentieth century and has since expanded into a highly successful research program to explore the processes of diversification and adaptation. Nonetheless, the ability of that framework satisfactorily to accommodate the rapid advances in developmental biology, genomics and ecology has been questioned. We review some of these arguments, focusing on literatures (evo-devo, developmental plasticity, inclusive inheritance and niche construction) whose implications for evolution can be interpreted in two ways—one that preserves the internal structure of contemporary evolutionary theory and one that points towards an alternative conceptual framework. The latter, which we label the ‘extended evolutionary synthesis' (EES), retains the fundaments of evolutionary theory, but differs in its emphasis on the role of constructive processes in development and evolution, and reciprocal portrayals of causation. In the EES, developmental processes, operating through developmental bias, inclusive inheritance and niche construction, share responsibility for the direction and rate of evolution, the origin of character variation and organism–environment complementarity. We spell out the structure, core assumptions and novel predictions of the EES, and show how it can be deployed to stimulate and advance research in those fields that study or use evolutionary biology. PMID:26246559

  2. The extended evolutionary synthesis: its structure, assumptions and predictions.

    PubMed

    Laland, Kevin N; Uller, Tobias; Feldman, Marcus W; Sterelny, Kim; Müller, Gerd B; Moczek, Armin; Jablonka, Eva; Odling-Smee, John

    2015-08-22

    Scientific activities take place within the structured sets of ideas and assumptions that define a field and its practices. The conceptual framework of evolutionary biology emerged with the Modern Synthesis in the early twentieth century and has since expanded into a highly successful research program to explore the processes of diversification and adaptation. Nonetheless, the ability of that framework satisfactorily to accommodate the rapid advances in developmental biology, genomics and ecology has been questioned. We review some of these arguments, focusing on literatures (evo-devo, developmental plasticity, inclusive inheritance and niche construction) whose implications for evolution can be interpreted in two ways—one that preserves the internal structure of contemporary evolutionary theory and one that points towards an alternative conceptual framework. The latter, which we label the 'extended evolutionary synthesis' (EES), retains the fundaments of evolutionary theory, but differs in its emphasis on the role of constructive processes in development and evolution, and reciprocal portrayals of causation. In the EES, developmental processes, operating through developmental bias, inclusive inheritance and niche construction, share responsibility for the direction and rate of evolution, the origin of character variation and organism-environment complementarity. We spell out the structure, core assumptions and novel predictions of the EES, and show how it can be deployed to stimulate and advance research in those fields that study or use evolutionary biology.

  3. Analyses for the National Commission on the Structure of the Air Force (Revised)

    DTIC Science & Technology

    2014-04-01

    the Air Force (Revised) Colin M. Doyle Stanley A. Horowitz Nancy M. Huff Shaun K. McGee Steven B. Walser INSTITUTE FOR DEFENSE ANALYSES 4850 Mark...M. Huff Shaun K. McGee Steven B. Walser Executive Summary This paper presents four short analyses performed by the Institute for Defense Analyses...Force F-16 Analysis Shaun K. McGee A. Introduction This chapter addresses the cost of Air Force F-16 aircraft squadrons. Units are modeled using Air

  4. An approximation based global optimization strategy for structural synthesis

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Schmit, L. A.

    1991-01-01

    A global optimization strategy for structural synthesis based on approximation concepts is presented. The methodology involves the solution of a sequence of highly accurate approximate problems using a global optimization algorithm. The global optimization algorithm implemented consists of a branch and bound strategy based on the interval evaluation of the objective function and constraint functions, combined with a local feasible directions algorithm. The approximate design optimization problems are constructed using first order approximations of selected intermediate response quantities in terms of intermediate design variables. Some numerical results for example problems are presented to illustrate the efficacy of the design procedure setforth.

  5. Synthesis, Structure and Reactivity of Molecules Attached to Electrode Surfaces.

    DTIC Science & Technology

    2014-09-26

    FAD-A1i58 621 SYNTHESIS STRUCTURE AND REACTIVITY OF MOLECULES - - BARBARA DEPT OF CHEMISTRY A T HUBBARD 18 JUL 85 UNCATACHED O ELETR-8D UR .)CLFO RN...PRINCIPAL INVESTIGATOR: Arthur T. Hubbard Professor, Department of Chemistry SUniversity of California Santa Barbara, CA 93106 (805) 961-3707 CO...3 "-627 GaL NAME OF PERFORMING ORGANIZATION b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION Department of Chemistry (,rappSi abi9 ,/C.- 6c

  6. Incompletely-Condensed Fluorinated Silsesquioxane: Synthesis and Crystal Structure

    DTIC Science & Technology

    2011-11-29

    other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a ...ABSTRACT A recently developed sub-class of POSS, fluorinated polyhedral oligomeric silsesquioxane (F-POSS), consists of a Si-O core with a periphery of...incompletely-condensed silsesquioxane, (CF3(CF2)7CH2CH2)8Si8O11(OH)2, has been synthesized via a multi-step synthesis (52% yield). The structure was

  7. Korean Anxiety Sensitivity Index-Revised: its factor structure, reliability, and validity in clinical and nonclinical samples.

    PubMed

    Lim, Young-Jin; Yu, Bum-Hee; Kim, Ji-Hae

    2007-01-01

    The factor structure and convergent and discriminant validity of the Anxiety Sensitivity Index-Revised (ASI-R) were examined in a community sample, a student sample, and patients with panic disorder in Korea. Results from a confirmatory factor analysis (CFA) comparing our data to factor solutions commonly reported as representative of European American populations indicated a poor fit. A subsequent exploratory factor analysis (EFA) indicated that a four-factor solution provided the best fit. Correlations between the ASI-R and anxiety measures were moderately high, providing evidence of convergent validity. Implications for assessment with Koreans are discussed.

  8. Planning and Revising Written Arguments: The Effects of Two Text Structure-Based Interventions on Persuasiveness of 8th-Grade Students' Essays

    ERIC Educational Resources Information Center

    Midgette, Ekaterina; Haria, Priti

    2016-01-01

    The purpose of the study was to investigate the effects of two comprehensive argumentative writing interventions--Text Structure Instruction (TSI) and Text Structure Revision Instruction (TSRI)--on the eighth-grade students' ability to compose convincing essays that include structural elements of argumentative discourse. Both treatment groups…

  9. Planning and Revising Written Arguments: The Effects of Two Text Structure-Based Interventions on Persuasiveness of 8th-Grade Students' Essays

    ERIC Educational Resources Information Center

    Midgette, Ekaterina; Haria, Priti

    2016-01-01

    The purpose of the study was to investigate the effects of two comprehensive argumentative writing interventions--Text Structure Instruction (TSI) and Text Structure Revision Instruction (TSRI)--on the eighth-grade students' ability to compose convincing essays that include structural elements of argumentative discourse. Both treatment groups…

  10. FANCJ promotes DNA synthesis through G-quadruplex structures.

    PubMed

    Castillo Bosch, Pau; Segura-Bayona, Sandra; Koole, Wouter; van Heteren, Jane T; Dewar, James M; Tijsterman, Marcel; Knipscheer, Puck

    2014-11-03

    Our genome contains many G-rich sequences, which have the propensity to fold into stable secondary DNA structures called G4 or G-quadruplex structures. These structures have been implicated in cellular processes such as gene regulation and telomere maintenance. However, G4 sequences are prone to mutations particularly upon replication stress or in the absence of specific helicases. To investigate how G-quadruplex structures are resolved during DNA replication, we developed a model system using ssDNA templates and Xenopus egg extracts that recapitulates eukaryotic G4 replication. Here, we show that G-quadruplex structures form a barrier for DNA replication. Nascent strand synthesis is blocked at one or two nucleotides from the G4. After transient stalling, G-quadruplexes are efficiently unwound and replicated. In contrast, depletion of the FANCJ/BRIP1 helicase causes persistent replication stalling at G-quadruplex structures, demonstrating a vital role for this helicase in resolving these structures. FANCJ performs this function independently of the classical Fanconi anemia pathway. These data provide evidence that the G4 sequence instability in FANCJ(-/-) cells and Fancj/dog1 deficient C. elegans is caused by replication stalling at G-quadruplexes.

  11. FANCJ promotes DNA synthesis through G-quadruplex structures

    PubMed Central

    Castillo Bosch, Pau; Segura-Bayona, Sandra; Koole, Wouter; van Heteren, Jane T; Dewar, James M; Tijsterman, Marcel; Knipscheer, Puck

    2014-01-01

    Our genome contains many G-rich sequences, which have the propensity to fold into stable secondary DNA structures called G4 or G-quadruplex structures. These structures have been implicated in cellular processes such as gene regulation and telomere maintenance. However, G4 sequences are prone to mutations particularly upon replication stress or in the absence of specific helicases. To investigate how G-quadruplex structures are resolved during DNA replication, we developed a model system using ssDNA templates and Xenopus egg extracts that recapitulates eukaryotic G4 replication. Here, we show that G-quadruplex structures form a barrier for DNA replication. Nascent strand synthesis is blocked at one or two nucleotides from the G4. After transient stalling, G-quadruplexes are efficiently unwound and replicated. In contrast, depletion of the FANCJ/BRIP1 helicase causes persistent replication stalling at G-quadruplex structures, demonstrating a vital role for this helicase in resolving these structures. FANCJ performs this function independently of the classical Fanconi anemia pathway. These data provide evidence that the G4 sequence instability in FANCJ−/− cells and Fancj/dog1 deficient C. elegans is caused by replication stalling at G-quadruplexes. PMID:25193968

  12. Factor Structure, Reliability, and Validity of the Japanese Version of the Disgust Propensity and Sensitivity Scale-Revised

    PubMed Central

    Tanaka, Tsunehiko; Yamada, Yuki

    2016-01-01

    The Disgust Propensity and Sensitivity Scale-Revised is one of the most widely used measures of individual differences for the emotion of disgust. It consists of 2 subscales: disgust propensity and disgust sensitivity. This study examined the factor structure, reliability, and validity of the Japanese version of the revised Disgust Propensity and Sensitivity Scale. Japanese participants (N = 1067) completed the scale as well as the Padua Inventory, Anxiety Sensitivity Index, State-Trait Anxiety Inventory, and Positive and Negative Affective Schedule. The participants were divided into 3 samples: Sample 1 (n = 481, mean age = 23.05, 186 males and 295 females); Sample 2 (n = 492, mean age = 20.27, 243 males and 249 females); and Sample 3 (n = 94, mean age = 22.68, 35 males and 58 females). We combined Samples 1 and 2 (n = 973, mean age = 21.66, 429 males and 544 females), and then created 2 subsamples to ensure the mutual independence of the samples used for two different factor analyses: subsample 1 (n = 486, mean age = 21.86, 199 male and 287 female) for exploratory factor analysis and subsample 2 (n = 487, mean age = 21.40, 230 male and 257 female) for confirmatory factor analysis. We examined test-retest reliability using Sample 3, and construct validity using Samples 1, 2, and the combined sample. Exploratory and confirmatory factor analyses revealed that the item-factor structure of the Japanese Disgust Propensity and Sensitivity Scale-Revised was identical to the English version. Moreover, the scale showed good internal consistency, test-retest reliability, and construct validity for empirical support as provided by correlational analyses. Results revealed adequate psychometric properties of the scale. This study provided the first examples of empirical support for the DPSS-R-J. PMID:27732659

  13. Discrete-continuous variable structural synthesis using dual methods

    NASA Technical Reports Server (NTRS)

    Schmit, L. A.; Fleury, C.

    1980-01-01

    Approximation concepts and dual methods are extended to solve structural synthesis problems involving a mix of discrete and continuous sizing type of design variables. Pure discrete and pure continuous variable problems can be handled as special cases. The basic mathematical programming statement of the structural synthesis problem is converted into a sequence of explicit approximate primal problems of separable form. These problems are solved by constructing continuous explicit dual functions, which are maximized subject to simple nonnegativity constraints on the dual variables. A newly devised gradient projection type of algorithm called DUAL 1, which includes special features for handling dual function gradient discontinuities that arise from the discrete primal variables, is used to find the solution of each dual problem. Computational implementation is accomplished by incorporating the DUAL 1 algorithm into the ACCESS 3 program as a new optimizer option. The power of the method set forth is demonstrated by presenting numerical results for several example problems, including a pure discrete variable treatment of a metallic swept wing and a mixed discrete-continuous variable solution for a thin delta wing with fiber composite skins.

  14. Computational simulation for analysis and synthesis of impact resilient structure

    NASA Astrophysics Data System (ADS)

    Djojodihardjo, Harijono

    2013-10-01

    Impact resilient structures are of great interest in many engineering applications varying from civil, land vehicle, aircraft and space structures, to mention a few examples. To design such structure, one has to resort fundamental principles and take into account progress in analytical and computational approaches as well as in material science and technology. With such perspectives, this work looks at a generic beam and plate structure subject to impact loading and carry out analysis and numerical simulation. The first objective of the work is to develop a computational algorithm to analyze flat plate as a generic structure subjected to impact loading for numerical simulation and parametric study. The analysis will be based on dynamic response analysis. Consideration is given to the elastic-plastic region. The second objective is to utilize the computational algorithm for direct numerical simulation, and as a parallel scheme, commercial off-the shelf numerical code is utilized for parametric study, optimization and synthesis. Through such analysis and numerical simulation, effort is devoted to arrive at an optimum configuration in terms of loading, structural dimensions, material properties and composite lay-up, among others. Results will be discussed in view of practical applications.

  15. Structure-Controlled Synthesis of Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Yan

    Single-walled carbon nanotubes (SWNTs) present structure-determined outstanding properties and SWNTs with a single (n, m) type are needed in many advanced applications. However, the chirality-specific growth of SWNTs is always a great challenge. Carbon nanotubes and their caps or catalysts can all act as the structural templates to guide the formation of SWNTs with a specified chirality. SWNT growth via a catalyzed chemical vapor deposition CVD process is normally more efficient and therefore of great interest. We developed a new family of catalyst, tungsten-based intermetallic nanocrystals, to grow SWNTs with specified chiral structures. Such intermetallic nanocrystals present unique structure and atomic arrangements, which are distinctly different from the normal alloy nanoparticles or simple metal nanocrystals, therefore can act as the template to grow SWNTs with designed (n, m) structures. Using W6Co7 catalysts, we realized the selective growth of (12, 6), (16, 0), (14, 4) and other chiralities. By the cooperation of thermodynamic and kinetic factors, SWNTs with high chirality purity can be obtained. . Structure-Controlled Synthesis of Single-Walled Carbon Nanotubes.

  16. Synthesis and structural characterization of three-layer Aurivillius ceramics

    NASA Astrophysics Data System (ADS)

    Haluska, Michael Stephan

    2003-07-01

    The three layer Aurivillius crystal structure was investigated for use as an ionic conductor. Sample synthesis was investigated using high temperature x-ray diffraction (HTXRD) for a range of compounds, using solid state synthesis and the polymerized complex method. Isothermal Avrami type kinetics studies were performed on Bi4Ti3O12 using in situ HTXRD and quantitative analysis performed via Rietveld refinements using TOPAS. The kinetics analysis yielded Avrami exponents of approximately 0.54, which fell in the range of the diffusion controlled reaction mechanisms. The activation energy over a range of temperatures was calculated to be on the order of 140kJ/mol. Crystal structure refinements were performed on the Bi2Sr2-xAxNb2TiO12 (A = Ca,Ba, x = 0.5, 1) series using combined x-ray and neutron diffraction Rietveld refinements. Refinements indicated a static disorder between the Bi and A sites, and between the Nb and Ti sites. A-site lattice strain investigated via the bond valence method reveals a linear increase in strain with the size of the substituted alkaline earth cation. Furthermore, large isotropic thermal parameters for the O1 and O4 oxygen sites reveal possible oxygen vacancy formation as a result of unresolved strain between the A and Ti layers of the structure. Oxygen stoichiometry is found to decrease as the size of the a lattice parameter decreases. Synthesis of non-stoichiometric three-layer phases was accomplished by aliovalent substitution and via forced site-mixing. Neither method produced samples with conductivities greater than 10-3 Scm at 900°C. Non-stoichiometric compositions follow similar structural trends to those observed in the stoichiometric crystal structure refinements. Increased numbers of oxygen vacancies were recorded than anticipated from the dopants. The number of extra vacancies corresponds well with the amount shown in the stoichiometric compositions. Based on the conductivity and number of charge carriers, the mobilities of

  17. Synthesis and structure of perovskite ScMnO3.

    PubMed

    Chen, Haiyan; Yu, Tian; Gao, Peng; Bai, Jianming; Tao, Jing; Tyson, Trevor A; Wang, Liping; Lalancette, Roger

    2013-08-19

    The rare-earth manganites RMnO3 (R = rare earth) are a class of important multiferroics with stable hexagonal structures for small R ion radius (Sc, Lu, Yb, ...). Metastable perovskite phases of these systems possess intriguing electronically driven electrical polarization, but the synthesis of the perovskite phase for the end member ScMnO3 system has proven to be elusive. We report the structure of a new monoclinic P2(1)/n perovskite phase of ScMnO3 synthesized from the hexagonal phase under high-pressure and high-temperature conditions. This extends the small ion region for so-called E-phase electronically driven ferroelectric manganese perovsites.

  18. An implementation of the programming structural synthesis system (PROSSS)

    NASA Technical Reports Server (NTRS)

    Rogers, J. L., Jr.; Sobieszczanski-Sobieski, J.; Bhat, R. B.

    1981-01-01

    A particular implementation of the programming structural synthesis system (PROSSS) is described. This software system combines a state of the art optimization program, a production level structural analysis program, and user supplied, problem dependent interface programs. These programs are combined using standard command language features existing in modern computer operating systems. PROSSS is explained in general with respect to this implementation along with the steps for the preparation of the programs and input data. Each component of the system is described in detail with annotated listings for clarification. The components include options, procedures, programs and subroutines, and data files as they pertain to this implementation. An example exercising each option in this implementation to allow the user to anticipate the type of results that might be expected is presented.

  19. Dual methods and approximation concepts in structural synthesis

    NASA Technical Reports Server (NTRS)

    Fleury, C.; Schmit, L. A., Jr.

    1980-01-01

    Approximation concepts and dual method algorithms are combined to create a method for minimum weight design of structural systems. Approximation concepts convert the basic mathematical programming statement of the structural synthesis problem into a sequence of explicit primal problems of separable form. These problems are solved by constructing explicit dual functions, which are maximized subject to nonnegativity constraints on the dual variables. It is shown that the joining together of approximation concepts and dual methods can be viewed as a generalized optimality criteria approach. The dual method is successfully extended to deal with pure discrete and mixed continuous-discrete design variable problems. The power of the method presented is illustrated with numerical results for example problems, including a metallic swept wing and a thin delta wing with fiber composite skins.

  20. Hydrothermal synthesis as a route to mineralogically-inspired structures.

    PubMed

    McMillen, Colin D; Kolis, Joseph W

    2016-02-21

    The use of high temperature hydrothermal reactions to prepare crystals having mineralogically-related structures is described. Complex naturally occurring minerals can have fascinating structures and exhibit important features like low dimensionality, noncentrosymmetry, or ion channels that can provide excellent guideposts for the designed synthesis of new materials. Actual minerals, even though they may have intriguing physical properties, are often unsuitable for study because of the persistent impurities inevitably present in natural samples. Hydrothermal fluids at relatively high temperatures provide access to large, high quality single crystals of structures with mineral-like structures. This enables the study of physical properties like ionic conduction, magnetic spin frustration and non-linear optical behavior. Some fundamental considerations of the hydrothermal technique are discussed in the context of synthesizing mineralogically-inspired materials. The metal vanadates provide a surprisingly rich and diversified range of compounds and are selected to illustrate many of the concepts described here. A series of low dimensional mineral analogs featuring isolated units, chains, and layers have been prepared in the laboratory as large single crystals using a high temperature hydrothermal synthetic methods, and their physical properties are under investigation. The metal silicates are also highlighted as another promising field of exploration, since their hydrothermal synthesis surprisingly lags behind the enormous literature of the natural silicate minerals. The introduction of heteroelements, such as boron to make borosilicates, appears to also open the door to additional new materials. Many of these new materials have direct equivalents in the mineral kingdom, while others have no known analogs but are reminiscent of minerals and can be classified in the same ways. From these initial results there appears to be a very rich vein of synthetic minerals waiting

  1. Synthesis and photocatalytic activity of titania microspheres with hierarchical structures

    SciTech Connect

    Cheng, Qian-Qian; Cao, Ying; Yang, Lin; Zhang, Pei-Pei; Wang, Kui; Wang, Hua-Jie

    2011-03-15

    Research highlights: {yields} Lauryl alcohol directs the formation of titania with hierarchical structures. {yields} Hierarchical structures endow the higher specific area to titania. {yields} Titania had a higher photocatalytic activity than commercial Degussa P25. {yields} The synthesis process of the target product is low-cost. -- Abstract: A combined sol-gel and solvothermal process was introduced to fabricate the titania microspheres with hierarchical structures by using lauryl alcohol as the structure-directing agent. Scanning electron microscope, high-resolution transmission electron microscope, Fourier transform infrared spectrograph and powder X-ray powder diffraction indicated that the molar ratio of lauryl alcohol, water and tetra-n-butyl titanate was the key factor for the formation of the mono-dispersed titania with anatase phase and the optimal ratio was 1.2:4:1. The diameter of the end-product was 523 {+-} 74 nm and it was composed of smaller nanoparticles with about 6.8 nm size in diameter. Photocatalytic activity of the end-product was investigated by employing Rhodamine B and Methylene blue as the model compounds. The target microspheres exhibited the higher photocatalytic efficiency compared with commercial Degussa P25 titania and this result might be due to the hierarchical structures of microspheres according to the analysis of Brunauer-Emmett-Teller specific surface areas.

  2. Factor Structure and Reliability of the Revised Conflict Tactics Scales' (CTS2) 10-Factor Model in a Community-Based Female Sample

    ERIC Educational Resources Information Center

    Yun, Sung Hyun

    2011-01-01

    The present study investigated the factor structure and reliability of the revised Conflict Tactics Scales' (CTS2) 10-factor model in a community-based female sample (N = 261). The underlying factor structure of the 10-factor model was tested by the confirmatory multiple group factor analysis, which demonstrated complex factor cross-loadings…

  3. Factor Structure and Reliability of the Revised Conflict Tactics Scales' (CTS2) 10-Factor Model in a Community-Based Female Sample

    ERIC Educational Resources Information Center

    Yun, Sung Hyun

    2011-01-01

    The present study investigated the factor structure and reliability of the revised Conflict Tactics Scales' (CTS2) 10-factor model in a community-based female sample (N = 261). The underlying factor structure of the 10-factor model was tested by the confirmatory multiple group factor analysis, which demonstrated complex factor cross-loadings…

  4. Alphavirus RNA synthesis and non-structural protein functions

    PubMed Central

    Rupp, Jonathan C.; Sokoloski, Kevin J.; Gebhart, Natasha N.

    2015-01-01

    The members of the genus Alphavirus are positive-sense RNA viruses, which are predominantly transmitted to vertebrates by a mosquito vector. Alphavirus disease in humans can be severely debilitating, and depending on the particular viral species, infection may result in encephalitis and possibly death. In recent years, alphaviruses have received significant attention from public health authorities as a consequence of the dramatic emergence of chikungunya virus in the Indian Ocean islands and the Caribbean. Currently, no safe, approved or effective vaccine or antiviral intervention exists for human alphavirus infection. The molecular biology of alphavirus RNA synthesis has been well studied in a few species of the genus and represents a general target for antiviral drug development. This review describes what is currently understood about the regulation of alphavirus RNA synthesis, the roles of the viral non-structural proteins in this process and the functions of cis-acting RNA elements in replication, and points to open questions within the field. PMID:26219641

  5. Synthesis and structure of 6-aminofulvene-2-aldiminate complexes.

    PubMed

    Willcocks, Alexander M; Gilbank, Alexander; Richards, Stephen P; Brayshaw, Simon K; Kingsley, Andrew J; Odedra, Raj; Johnson, Andrew L

    2011-02-07

    We report here a synthetic route to bis(N,N'-aryl)-6-aminofulvene-2-aldimine (AFA) ligand systems, specifically Ph(2)-AFAH and Dip(2)-AFAH. The synthesis and structural characterization of a series of Cu(I) complexes [(Ph(2)-AFA)Cu(CNPh)(2)] (2), [(Ph(2)-AFA)Cu(CN(i)Pr)] (3), and [(Dip(2)-AFA)Cu(CN(i)Pr)] (4), from the reaction of the corresponding lithiated AFA systems with Cu-Cl derivatives are reported; notably in the case of [(Ph(2)-AFA)Cu(CNPh)(2)] studies have revealed the existence of two structural isomers (2a and 2b), both of which can be isolated and structurally characterized. Density functional theory (DFT) calculations suggest that the two crystal forms are comparatively close in energy, and geometry optimization reveals a convergence of these two forms to a geometry that more closely resembles the solid-state structure of isomer 2b, having a CH···π interaction. The reactions of the AFA compounds Ph(2)-AFAH and Dip(2)-AFAH with ZnMe(2) and AlMe(3) have also been investigated, and the results of these reactions are described here.

  6. Contractual Revision.

    ERIC Educational Resources Information Center

    Engel, Mary F.; Sawyer, Thomas M.

    Contractual revision promotes cooperation between teachers and tutors and, being student initiated, provides a method to increase student control over the revision process and encourage students to communicate their strengths and weaknesses in writing to their teachers or tutors. The contractual revision process requires students to form contracts…

  7. Scalable Synthesis of Cortistatin A and Related Structures

    PubMed Central

    Shi, Jun; Manolikakes, Georg; Yeh, Chien-Hung; Guerrero, Carlos A.; Shenvi, Ryan A.; Shigehisa, Hiroki

    2011-01-01

    Full details are provided for an improved synthesis of cortistatin A and related structures as well as the underlying logic and evolution of strategy. The highly functionalized cortistatin A-ring embedded with a key heteroadamantane was synthesized by a simple and scalable 5-step sequence. A chemoselective, tandem geminal dihalogenation of an unactivated methyl group, a reductive fragmentation/trapping/elimination of a bromocyclopropane, and a facile chemoselective etherification reaction afforded the cortistatin A core, dubbed “cortistatinone”. A selective Δ16-alkene reduction with Raney Ni provided cortistatin A. With this scalable and practical route, copious quantities of cortistatinone, Δ16-cortistatin A-the equipotent direct precursor to cortistatin A, and its related analogs were prepared for further biological studies. PMID:21539314

  8. Hexamethylenetetramine carboxyborane: synthesis, structural characterization and CO releasing properties.

    PubMed

    Ayudhya, T I; Raymond, C C; Dingra, N N

    2017-01-17

    Carbon monoxide, although widely known as a toxic gas, has received great attention in the past few decades due to its promising role as a medical gas. Several classes of carbon monoxide releasing molecules (CORMs) have been synthesised with many of them having pharmacological activities under physiological conditions. Herein, we report the synthesis and structural characterization of the first example of amine carboxyborane that releases CO under physiological conditions without the aid of inducers. A representative compound hexamethylenetetramine carboxyborane (HMTA-CB) described here has a half-life of 2.7 days and gradually releases CO with the rate constant of 3.0 × 10(-6) s(-1). Its ability to promote cell growth shows the beneficial effect of slow CO release to supplement CO in small amounts over time.

  9. Perovskite oxide nanowires: synthesis, property and structural characterization.

    PubMed

    Zhu, Xinhua; Liu, Zhiguo; Ming, Naiben

    2010-07-01

    Perovskite oxide materials display a wide spectrum of functional properties, including switchable polarization, piezoelectricity, pyroelectricity, and non-linear dielectric behavior. These properties are indispensable for application in electronic devices such as non-volatile memories, sensors, microactuators, infrared detectors, microwave phase filters, and so on. Recent advances in science and technology of perovskite oxide materials have resulted in the feature sizes of perovskite oxides-based electronic devices entering into nanoscale dimensions. At nanoscale perovskite oxide materials exhibit a pronounced size effect manifesting itself in a significant deviation of the properties of low-dimensional structures from the bulk and film counterparts. In the last decade low-dimensional perovskite nanosized oxides have been received much attention because of their superior physical and chemical properties. Among them, perovskite oxide nanowires are especially attractive for nanoscience studies and nanotechnology applications. Compared to other low-dimensional perovskite oxide systems, perovskite oxide nanowires are not only used as the building blocks of future nanodevices, but also they offer fundamental scientific opportunities for investigating the intrinsic size effects of physical properties. In the recent years, much progress has been made both in synthesis and physical property testing of perovskite oxide nanowires, which have a profound impact on the nanoelectronics. In this work, an overview of the state of art in perovskite oxide nanowires is presented, which covers their synthesis, property, and structural characterization. In the first part, the recent literatures for fabricating perovskite oxide nanowires with promising features, are critically reviewed. The second part deals with the recent advances on the physical property testing of perovskite oxide nanowires. The third part summarizes the recent progress on microstructural characterizations of

  10. Synthesis, structure and magnetism in copper chalcochromite spinels

    NASA Astrophysics Data System (ADS)

    Neulinger, Janell Rebecca

    The copper chalcochromites (CuCr2X4 (X = S, Se, Te)) possess a rare combination of magnetic and electronic properties compared to other chalcogenide spinet materials. A precise structural and magnetic investigation of these materials was undertaken in order to facilitate technological exploitation of these unusual properties. CuCr2Se4, several halogenated derivatives of the form CuCr2Se4 -xXx (with X = Cl, Br, or I), and CuCr2S3Cl were prepared via powder methods and chemical vapor transport growth of single crystals. A variety of X-ray diffraction techniques were employed to determine the crystal structures of the synthesis products. The materials adopt a trigonal variation of the spinet structure type; the lower-symmetry structure includes a single threefold roto-inversion axis. Halogen doping introduces systematic changes in the properties of the chalcochromites, and the effects of halogen doping were monitored by magnetometry, soft X-ray spectroscopy, and magnetic microscopy techniques. Bulk magnetic properties were characterized by SQUID and vibrating sample magnetometry, at temperatures from 5 K to above the Curie temperatures. Soft X-ray spectroscopic measurements performed at the Advanced Light Source at Lawrence Berkeley National Laboratory included X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) experiments. Dichroic spectra at the Cr L2,3 and Cu L 2,3 absorption edges confirm a ferrimagnetic model of opposing magnetic sub-lattices localized on the Cr and Cu centers; increasing levels of halogen doping suppress the contribution from the copper sublattice and reduce T C. Magnetic domain imaging using the Photoelectron Electron Microscope (PEEM) at the Advanced Light Source indicates the presence of a variety of domain morphologies, including predominantly stripe domains reflecting the uniaxial symmetry of the trigonal spinel structure. The magnetic and structural features of the copper chalcochromites mark them as robust, tunable, and

  11. A new structural analysis/synthesis capability - ACCESS. [Approximation Concepts Code for Efficient Structural Synthesis

    NASA Technical Reports Server (NTRS)

    Schmit, L. A.; Miura, H.

    1975-01-01

    The creation of an efficient automated capability for minimum weight design of structures is reported. The ACCESS 1 computer program combines finite element analysis techniques and mathematical programming algorithms using an innovative collection of approximation concepts. Design variable linking, constraint deletion techniques and approximate analysis methods are used to generate a sequence of small explicit mathematical programming problems which retain the essential features of the design problem. Organization of the finite element analysis is carefully matched to the design optimization task. The efficiency of the ACCESS 1 program is demonstrated by giving results for several example problems.

  12. Structural Revisions of a Class of Natural Products: Scaffolds of Aglycon Analogues of Fusicoccins and Cotylenins Isolated from Fungi.

    PubMed

    Tang, Ying; Xue, Yongbo; Du, Guang; Wang, Jianping; Liu, Junjun; Sun, Bin; Li, Xiao-Nian; Yao, Guangmin; Luo, Zengwei; Zhang, Yonghui

    2016-03-14

    The reisolation and structural revision of brassicicene D is described, and inspired us to reassign the core skeletons of brassicicenes C-H, J and K, ranging from dicyclopenta[a,d]cyclooctane to tricyclo[9.2.1.0(3,7)]tetradecane using quantum-chemical predictions and experimental validation strategies. Three novel, highly modified fusicoccanes, brassicicenes L-N, were also isolated from the fungus Alternaria brassicicola, and their structures were unequivocally established by spectroscopic data, ECD calculations, and crystallography. The reassigned structures represent the first class of bridgehead double-bond-containing natural products with a bicyclo[6.2.1]undecane carbon skeleton. Furthermore, their stabilities were first predicted with olefin strain energy calculations. Collectively, these findings extend our view of the application of computational predictions and biosynthetic logic-based structure elucidation to address problems related to the structure and stability of natural products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesis, base pairing and structure studies of geranylated RNA

    PubMed Central

    Wang, Rui; Vangaveti, Sweta; Ranganathan, Srivathsan V.; Basanta-Sanchez, Maria; Haruehanroengra, Phensinee; Chen, Alan; Sheng, Jia

    2016-01-01

    Natural RNAs utilize extensive chemical modifications to diversify their structures and functions. 2-Thiouridine geranylation is a special hydrophobic tRNA modification that has been discovered very recently in several bacteria, such as Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa and Salmonella Typhimurium. The geranylated residues are located in the first anticodon position of tRNAs specific for lysine, glutamine and glutamic acid. This big hydrophobic terpene functional group affects the codon recognition patterns and reduces frameshifting errors during translation. We aimed to systematically study the structure, function and biosynthesis mechanism of this geranylation pathway, as well as answer the question of why nature uses such a hydrophobic modification in hydrophilic RNA systems. Recently, we have synthesized the deoxy-analog of S-geranyluridine and showed the geranylated T-G pair is much stronger than the geranylated T-A pair and other mismatched pairs in the B-form DNA duplex context, which is consistent with the observation that the geranylated tRNAGluUUC recognizes GAG more efficiently than GAA. In this manuscript we report the synthesis and base pairing specificity studies of geranylated RNA oligos. We also report extensive molecular simulation studies to explore the structural features of the geranyl group in the context of A-form RNA and its effect on codon–anticodon interaction during ribosome binding. PMID:27307604

  14. High octane ethers from synthesis gas-derived alcohols. Quarterly technical progress report, October--December 1992, Revision 1

    SciTech Connect

    Klier, K.; Herman, R.G.; Johansson, M.A.; Feeley, O.C.

    1993-04-01

    The objective of the proposed research is to synthesize high octane ethers, primarily methyl isobutyl ether (MIBE) and methyl tertiary butyl ether (MTBE) directly from H{sub 2}/CO/CO{sub 2} coal-derived synthesis gas via alcohol mixtures that are rich in methanol and 2-methyl-l-propanol (isobutanol). The overall scheme involves gasification of coal, purification and shifting of the synthesis gas, higher alcohol synthesis, and direct synthesis of ethers. The testing of strongly acidic catalysts for the conversion of a mixture of methanol and isobutanol to ethers and hydrocarbons was continued. Under standardized test conditions the catalysts tested this quarter were: phosphotungstic acid supported on zirconia (PW{sub 12}/ZrO{sub 2}), ``niobic acid`` (Nb{sub 2}O{sub 5}{center_dot}xH{sub 2}O), and an iron and manganese doped sulfate-modified zirconia (Fe/Mn/ZrO{sub 2}/SO{sub 4}{sup 2{minus}}). The overall activity of these catalysts followed the order of Fe/Mn/ZrO{sub 2}/SO{sub 4}{sup 2{minus}} > PW{sub 12}/ZrO{sub 2} >Nb{sub 2}O{sub 5}{center_dot}xH{sub 2}O With the Fe/Mn/ZrO{sub 2}/SO{sub 4}{sup 2{minus}} catalyst approaching ZrO{sub 2}/SO{sub 4}{sup 2{minus}} in both activity and selectivity for isobutene production. The effect of the presence of water on the reaction of methanol and isobutanol over ZrO{sub 2}/SO{sub 4}{sup 2{minus}} was determined to be insignificant under the reaction conditions investigated.

  15. Synthesis, Structure, Stability and Redispersion of Gold-based Nanoparticles

    NASA Astrophysics Data System (ADS)

    Tiruvalam, Ram Chandra

    Nanoscale gold has been shown to possess an intriguing combination of unexpected optical, photochemical and catalytic properties. The ability to control the size, shape, morphology, composition and dispersion of gold-based nanostructures is key to optimizing their performance for nanotechnology applications. The advanced electron microscopy studies described in this thesis analyze three important aspects of gold and gold-palladium alloy nanoparticles: namely, (i) the ability to synthesize gold nanoparticles of controlled size and shape in an aqueous medium; (ii) the colloidal preparation of designer gold-palladium alloys for selective oxidation catalysis; and (iii) the ability to disperse gold as finely and homogeneously as possible on a metal oxide or carbon support. The ability to exploit the nanoscale properties of gold for various engineering applications often depends on our ability to control size and shape of the nanoscale entity by careful manipulation of the synthesis parameters. We have explored an aqueous based synthesis route, using oleylamine as both a reductant and surfactant, for preparing gold nanostructures. By systematically varying synthesis parameters such as oleylamine concentration, reaction temperature, and aging time it is possible to identify processing regimens that generate Au nanostructures having either pseudo-spherical, faceted polyhedral, nanostar or wire shaped morphologies. Furthermore, by quenching the reaction partway through it is possible to create a class of metastable Au-containing structures such as nanocubes, nanoboxes and nanowires. Possible formation mechanisms for these gold based nano-objects are discussed. There is a growing interest in using supported bimetallic AuPd alloy nanoparticles for selective oxidation reactions. In this study, a systematic series of size controlled AuPd bimetallic particles have been prepared by colloidal synthesis methods. Particles having random alloy structures, as well as `designer

  16. Fluorinated proteins: from design and synthesis to structure and stability.

    PubMed

    Marsh, E Neil G

    2014-10-21

    Fluorine is all but absent from biology; however, it has proved to be a remarkably useful element with which to modulate the activity of biological molecules and to study their mechanism of action. Our laboratory's interest in incorporating fluorine into proteins was stimulated by the unusual physicochemical properties exhibited by perfluorinated small molecules. These include extreme chemical inertness and thermal stability, properties that have made them valuable as nonstick coatings and fire retardants. Fluorocarbons also exhibit an unusual propensity to phase segregation. This phenomenon, which has been termed the "fluorous effect", has been effectively exploited in organic synthesis to purify compounds from reaction mixtures by extracting fluorocarbon-tagged molecules into fluorocarbon solvents. As biochemists, we were curious to explore whether the unusual physicochemical properties of perfluorocarbons could be engineered into proteins. To do this, we developed a synthesis of a highly fluorinated amino acid, hexafluoroleucine, and designed a model 4-helix bundle protein, α4H, in which the hydrophobic core was packed exclusively with leucine. We then investigated the effects of repacking the hydrophobic core of α4H with various combinations of leucine and hexafluoroleucine. These initial studies demonstrated that fluorination is a general and effective strategy for enhancing the stability of proteins against chemical and thermal denaturation and proteolytic degradation. We had originally envisaged that the "fluorous interactions", postulated from the self-segregating properties of fluorous solvents, might be used to mediate specific protein-protein interactions orthogonal to those of natural proteins. However, various lines of evidence indicate that no special, favorable fluorine-fluorine interactions occur in the core of the fluorinated α4 protein. This makes it unlikely that fluorinated amino acids can be used to direct protein-protein interactions. More

  17. New structure for the O-polysaccharide of Providencia alcalifaciens O27 and revised structure for the O-polysaccharide of Providencia stuartii O43.

    PubMed

    Ovchinnikova, Olga G; Bushmarinov, Ivan S; Kocharova, Nina A; Toukach, Filip V; Wykrota, Marianna; Shashkov, Alexander S; Knirel, Yuriy A; Rozalski, Antoni

    2007-06-11

    The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide from Providencia alcalifaciens O27 and studied by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, H-detected (1)H,(13)C HSQC, and HMBC experiments. It was found that the polysaccharide is built up of linear partially O-acetylated tetrasaccharide repeating units and has the following structure: [structure: see text] where Qui4NFo stands for 4-formamido-4,6-dideoxyglucose (4-formamido-4-deoxyquinovose). The O-polysaccharide structure of Providencia stuartii O43 established earlier was revised with respect to the configuration of the constituent 4-amino-4,6-dideoxyhexose (from Rha4N to Qui4N).

  18. Hollow-structured mesoporous materials: chemical synthesis, functionalization and applications.

    PubMed

    Li, Yongsheng; Shi, Jianlin

    2014-05-28

    Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis and structure of nanocrystalline mixed Ce–Yb silicates

    SciTech Connect

    Małecka, Małgorzata A. Kępiński, Leszek

    2013-07-15

    Graphical abstract: - Highlights: • New method of synthesis of nanocrystalline mixed lanthanide silicates is proposed. • Formation of A-type (Ce{sub 1−y}Yb{sub y}){sub 2}Si{sub 2}O{sub 7} in well dispersed Ce{sub 1−x}Yb{sub x}O{sub 2−(x/2)}–SiO{sub 2} system. • Formation of Yb{sub y}Ce{sub 9.33−y}(SiO{sub 4}){sub 6}O{sub 2} in agglomerated Ce{sub 1−x}Yb{sub x}O{sub 2−(x/2)}–SiO{sub 2} system. - Abstract: This work presents results of studies on synthesis and structure of mixed, nanocrystalline Ce–Yb silicates. Using TEM, XRD and FTIR we showed that heat treatment of nanocrystalline Ce{sub 1−x}Yb{sub x}O{sub 2−(x/2)} (x = 0.3, 0.5) mixed oxide supported on amorphous silica in reducing atmosphere, results in formation of Ce–Yb mixed silicates. Dispersion of the oxide on the silica surface and thus a local lanthanide/Si atomic ratio determines the stoichiometry of the silicate. Oxide crystallites uniformly dispersed on the silica surface transformed into A-(Ce{sub 1−y}Yb{sub y}){sub 2}Si{sub 2}O{sub 7} disilicate, while the agglomerated nanoparticles converted into Yb{sub y}Ce{sub 9.33−y}(SiO{sub 4}){sub 6}O{sub 2} oxyapatite silicate as an intermediate phase.

  20. Examining the Impact of Gender on the Factor Structure of the Psychopathic Personality Inventory--Revised

    ERIC Educational Resources Information Center

    Anestis, Joye C.; Caron, Kelly M.; Carbonell, Joyce L.

    2011-01-01

    Research on the factor structure of psychopathy has yielded mixed results, supporting anywhere from one to three factors. Additionally, most of this research has used all-male samples, and the possibility of structural invariance across gender has not been examined. Using a mixed-gender sample of 360 undergraduates, the factor structure of the…

  1. Thioanalogues of N-1-methylanabasine and nicotine - Synthesis and structure

    NASA Astrophysics Data System (ADS)

    Wojciechowska-Nowak, Marzena; Boczoń, Władysław; Warżajtis, Beata; Rychlewska, Urszula; Jasiewicz, Beata

    2011-03-01

    The synthesis, spectral characteristics and structures of N-1-methyl-6-(pyridin-3-yl)piperidine-2-thione ( 1) (thioanalogue of N-1-methylanabasine) and N-1-methyl-(5-pyridin-3-yl)pyrrolidine-2-thione ( 2) (thioanalogue of nicotine) are reported. Both compounds were obtained using Lawesson's reagent. The structures of compounds 1 and 2 are confirmed by NMR, IR, UV and mass spectroscopy, as well as, by X-ray diffraction analysis. Pyridine ring of compound 1 adopts a pseudo-axial orientation in solution, as well as in a solid state. A substantial lengthening of the C dbnd S bond in the crystals of 1 is interpreted as a sign of an enhanced electron delocalization within the thiolactam group due to the presence of several C sbnd H groups in the nearest vicinity of the sulfur atom. In the crystals of 2, which differ from 1 in that the relatively puckered piperidine-2-thione moiety is replaced by the flat pyrrolidine-2-thione ring, no short CH⋯S( dbnd C) contacts are observed. Instead, the packing is governed by stacking interactions between pyridine rings. The pyrrolidine and pyridine rings in 2 are nearly perpendicular to each other and the pyrrolidine moiety adopts a flattened half-chair conformation.

  2. Resonant active sites in catalytic ammonia synthesis: A structural model

    NASA Astrophysics Data System (ADS)

    Cholach, Alexander R.; Bryliakova, Anna A.; Matveev, Andrey V.; Bulgakov, Nikolai N.

    2016-03-01

    Adsorption sites Mn consisted of n adjacent atoms M, each bound to the adsorbed species, are considered within a realistic model. The sum of bonds Σ lost by atoms in a site in comparison with the bulk atoms was used for evaluation of the local surface imperfection, while the reaction enthalpy at that site was used as a measure of activity. The comparative study of Mn sites (n = 1-5) at basal planes of Pt, Rh, Ir, Fe, Re and Ru with respect to heat of N2 dissociative adsorption QN and heat of Nad + Had → NHad reaction QNH was performed using semi-empirical calculations. Linear QN(Σ) increase and QNH(Σ) decrease allowed to specify the resonant Σ for each surface in catalytic ammonia synthesis at equilibrium Nad coverage. Optimal Σ are realizable for Ru2, Re2 and Ir4 only, whereas other centers meet steric inhibition or unreal crystal structure. Relative activity of the most active sites in proportion 5.0 × 10- 5: 4.5 × 10- 3: 1: 2.5: 3.0: 1080: 2270 for a sequence of Pt4, Rh4, Fe4(fcc), Ir4, Fe2-5(bcc), Ru2, Re2, respectively, is in agreement with relevant experimental data. Similar approach can be applied to other adsorption or catalytic processes exhibiting structure sensitivity.

  3. The Anxiety Sensitivity Index--Revised: Confirmatory Factor Analyses, Structural Invariance in Caucasian and African American Samples, and Score Reliability and Validity

    ERIC Educational Resources Information Center

    Arnau, Randolph C.; Broman-Fulks, Joshua J.; Green, Bradley A.; Berman, Mitchell E.

    2009-01-01

    The most commonly used measure of anxiety sensitivity is the 36-item Anxiety Sensitivity Index--Revised (ASI-R). Exploratory factor analyses have produced several different factors structures for the ASI-R, but an acceptable fit using confirmatory factor analytic approaches has only been found for a 21-item version of the instrument. We evaluated…

  4. The Anxiety Sensitivity Index--Revised: Confirmatory Factor Analyses, Structural Invariance in Caucasian and African American Samples, and Score Reliability and Validity

    ERIC Educational Resources Information Center

    Arnau, Randolph C.; Broman-Fulks, Joshua J.; Green, Bradley A.; Berman, Mitchell E.

    2009-01-01

    The most commonly used measure of anxiety sensitivity is the 36-item Anxiety Sensitivity Index--Revised (ASI-R). Exploratory factor analyses have produced several different factors structures for the ASI-R, but an acceptable fit using confirmatory factor analytic approaches has only been found for a 21-item version of the instrument. We evaluated…

  5. Development and validation of the revised Identity Style Inventory (ISI-5): factor structure, reliability, and validity.

    PubMed

    Berzonsky, Michael D; Soenens, Bart; Luyckx, Koen; Smits, Ilse; Papini, Dennis R; Goossens, Luc

    2013-09-01

    Identity processing style refers to differences in how individuals process identity-relevant information as they engage or manage to avoid the challenges of constructing, maintaining, and/or reconstructing a sense of identity. The third version of the Identity Style Inventory (Berzonsky, 1992b) has been used to operationally define identity styles in most empirical investigations. The objective of the present series of studies was the development and validation of a new revised measure of identity processing style: Identity Style Inventory-Version 5 (ISI-5). Initially a pool of 39 generic items was generated that highlighted the processing of identity-relevant information on content-neutral issues such as personal values, goals, problems, and the like. Three style scales were identified by Exploratory Factor Analysis: A 9-item Informational-style scale; a 9-item Normative-style scale; and a 9-item Diffuse-avoidant style scale. Confirmatory factor analysis on an independent sample indicated that this 3-factor solution provided the best fit. Results from 5 studies provided evidence for the psychometric properties of the scales. Scores on the 3 style scales demonstrated good test-retest reliability and internal consistency. Theoretically predicted correlations between the ISI-5 scale scores and performance on measures of identity status, content, and commitment, and measures of rational and automatic processing provided evidence for their convergent and discriminant validity. It is concluded that the scales should be useful for researchers interested in investigating individual differences in identity processing style. Limitations and directions for future research are considered.

  6. Factor structure and item level psychometrics of the Social Problem Solving Inventory-Revised: Short Form in traumatic brain injury.

    PubMed

    Li, Chih-Ying; Waid-Ebbs, Julia; Velozo, Craig A; Heaton, Shelley C

    2016-01-01

    Social problem-solving deficits characterise individuals with traumatic brain injury (TBI), and poor social problem solving interferes with daily functioning and productive lifestyles. Therefore, it is of vital importance to use the appropriate instrument to identify deficits in social problem solving for individuals with TBI. This study investigates factor structure and item-level psychometrics of the Social Problem Solving Inventory-Revised: Short Form (SPSI-R:S), for adults with moderate and severe TBI. Secondary analysis of 90 adults with moderate and severe TBI who completed the SPSI-R:S was performed. An exploratory factor analysis (EFA), principal components analysis (PCA) and Rasch analysis examined the factor structure and item-level psychometrics of the SPSI-R:S. The EFA showed three dominant factors, with positively worded items represented as the most definite factor. The other two factors are negative problem-solving orientation and skills; and negative problem-solving emotion. Rasch analyses confirmed the three factors are each unidimensional constructs. It was concluded that the total score interpretability of the SPSI-R:S may be challenging due to the multidimensional structure of the total measure. Instead, we propose using three separate SPSI-R:S subscores to measure social problem solving for the TBI population.

  7. Dental beliefs: factor structure of the revised dental beliefs survey in a group of regular dental patients.

    PubMed

    Abrahamsson, Kajsa H; Ohrn, Kerstin; Hakeberg, Magnus

    2009-12-01

    The aim of this study was to investigate the factor structure of the revised dental beliefs survey (DBS-R) in a group of regular dental patients. The study group consisted of 278 patients (mean age 54 yr), 61% of whom were women. The DBS-R item mean value was 1.6. Principal component analysis (PCA) and confirmatory factor analysis (CFA) were performed. The initial PCA among the 28 DBS-R items showed four factors with eigenvalues of > 1 explaining 67% of the total variance. Five different CFA models were tested. The final model revealed a four-factor solution with one second-order factor (i.e. a hierarchical CFA). Thus, the latent second-order variable, 'dental beliefs', explains the variance from all DBS-R items through the four first-order factors labeled 'ethics', 'belittlement', 'communication and empathy', and 'control and anxiety'. The results suggest a somewhat different factor structure of DBS-R than previously reported for dental-fear patients. Hence, the underlying factor structure of the DBS-R may differ between different patient groups. The results point towards the use of the original 28-item DBS-R and interpreting the scale as measuring an overall construct of 'dental beliefs' and thus patients' attitudes and feelings related to dentists and dentistry.

  8. Factor Structure and Item Level Psychometrics of the Social Problem Solving Inventory Revised-Short Form in Traumatic Brain Injury

    PubMed Central

    Li, Chih-Ying; Waid-Ebbs, Julia; Velozo, Craig A.; Heaton, Shelley C.

    2016-01-01

    Primary Objective Social problem solving deficits characterize individuals with traumatic brain injury (TBI). Poor social problem solving interferes with daily functioning and productive lifestyles. Therefore, it is of vital importance to use the appropriate instrument to identify deficits in social problem solving for individuals with TBI. This study investigates factor structure and item-level psychometrics of the Social Problem Solving Inventory-Revised Short Form (SPSI-R:S), for adults with moderate and severe TBI. Research Design Secondary analysis of 90 adults with moderate and severe TBI who completed the SPSI-R:S. Methods and Procedures An exploratory factor analysis (EFA), principal components analysis (PCA) and Rasch analysis examined the factor structure and item-level psychometrics of the SPSI-R:S. Main Outcomes and Results The EFA showed three dominant factors, with positively worded items represented as the most definite factor. The other two factors are negative problem solving orientation and skills; and negative problem solving emotion. Rasch analyses confirmed the three factors are each unidimensional constructs. Conclusions The total score interpretability of the SPSI-R:S may be challenging due to the multidimensional structure of the total measure. Instead, we propose using three separate SPSI-R:S subscores to measure social problem solving for the TBI population. PMID:26052731

  9. The structural and predictive properties of the Psychopathy Checklist--revised in Canadian aboriginal and non-aboriginal offenders.

    PubMed

    Olver, Mark E; Neumann, Craig S; Wong, Stephen C P; Hare, Robert D

    2013-03-01

    We examined the structural and predictive properties of the Psychopathy Checklist-Revised (PCL-R) in large samples of Canadian male Aboriginal and non-Aboriginal offenders. The PCL-R ratings were part of a risk assessment for criminal recidivism, with a mean follow-up of 26 months postrelease. Using multigroup confirmatory factor analysis, we were able to show that the PCL-R items were invariant across these 2 groups and that a 4-factor model fit the data well. Predictive accuracy analyses (receiver operator characteristic curves and Cohen's d) generated effect sizes that were medium in magnitude overall for the PCL-R total score in the prediction of violent, nonviolent, and general criminal recidivism (area under the curve=.63-.70, Cohen's d=.28-.42) for both ancestral groups. When disaggregated into its constituent factors, for both ancestral groups, the Lifestyle and Antisocial factors consistently and significantly predicted all recidivism outcomes, whereas the Interpersonal and Affective factors did not significantly predict any of the recidivism outcomes. Finally, structural equation modeling results with the total sample indicated that the PCL-R factors were able to account for 32% of the variance in a latent recidivism factor. Implications regarding the latent structure of psychopathy and the clinical use of the instrument with Aboriginal and non-Aboriginal male offenders are discussed.

  10. Ligand-protected gold clusters: the structure, synthesis and applications

    NASA Astrophysics Data System (ADS)

    Pichugina, D. A.; Kuz'menko, N. E.; Shestakov, A. F.

    2015-11-01

    Modern concepts of the structure and properties of atomic gold clusters protected by thiolate, selenolate, phosphine and phenylacetylene ligands are analyzed. Within the framework of the superatom theory, the 'divide and protect' approach and the structure rule, the stability and composition of a cluster are determined by the structure of the cluster core, the type of ligands and the total number of valence electrons. Methods of selective synthesis of gold clusters in solution and on the surface of inorganic composites based, in particular, on the reaction of Aun with RS, RSe, PhC≡C, Hal ligands or functional groups of proteins, on stabilization of clusters in cavities of the α-, β and γ-cyclodextrin molecules (Au15 and Au25) and on anchorage to a support surface (Au25/SiO2, Au20/C, Au10/FeOx) are reviewed. Problems in this field are also discussed. Among the methods for cluster structure prediction, particular attention is given to the theoretical approaches based on the density functional theory (DFT). The structures of a number of synthesized clusters are described using the results obtained by X-ray diffraction analysis and DFT calculations. A possible mechanism of formation of the SR(AuSR)n 'staple' units in the cluster shell is proposed. The structure and properties of bimetallic clusters MxAunLm (M=Pd, Pt, Ag, Cu) are discussed. The Pd or Pt atom is located at the centre of the cluster, whereas Ag and Cu atoms form bimetallic compounds in which the heteroatom is located on the surface of the cluster core or in the 'staple' units. The optical properties, fluorescence and luminescence of ligand-protected gold clusters originate from the quantum effects of the Au atoms in the cluster core and in the oligomeric SR(AuSR)x units in the cluster shell. Homogeneous and heterogeneous reactions catalyzed by atomic gold clusters are discussed in the context of the reaction mechanism and the nature of the active sites. The bibliography includes 345 references.

  11. SSME/side loads analysis for flight configuration, revision A. [structural analysis of space shuttle main engine under side load excitation

    NASA Technical Reports Server (NTRS)

    Holland, W.

    1974-01-01

    This document describes the dynamic loads analysis accomplished for the Space Shuttle Main Engine (SSME) considering the side load excitation associated with transient flow separation on the engine bell during ground ignition. The results contained herein pertain only to the flight configuration. A Monte Carlo procedure was employed to select the input variables describing the side load excitation and the loads were statistically combined. This revision includes an active thrust vector control system representation and updated orbiter thrust structure stiffness characteristics. No future revisions are planned but may be necessary as system definition and input parameters change.

  12. New multirate sampled-data control law structure and synthesis algorithm

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.; Yang, Gen-Sheng

    1992-01-01

    A new multirate sampled-data control law structure is defined and a new parameter-optimization-based synthesis algorithm for that structure is introduced. The synthesis algorithm can be applied to multirate, multiple-input/multiple-output, sampled-data control laws having a prescribed dynamic order and structure, and a priori specified sampling/update rates for all sensors, processor states, and control inputs. The synthesis algorithm is applied to design two-input, two-output tip position controllers of various dynamic orders for a sixth-order, two-link robot arm model.

  13. A new multirate sampled-data control law structure and synthesis algorithm

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.; Yang, Gen-Sheng

    1991-01-01

    A new multirate sampled-data control law structure is defined and a new parameter-optimization-based synthesis algorithm for that structure is introduced. The synthesis algorithm can be applied to multirate, multiple-input multiple-output, sampled-data control laws having a prescribed dynamic order and structure, and a priori specified sampling/update rates for all sensors, processor states, and control inputs. The synthesis algorithm is applied to design two-input, two-output tip position controllers of various dynamic orders for a sixth-order, two-link robot arm model.

  14. New multirate sampled-data control law structure and synthesis algorithm

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.; Yang, Gen-Sheng

    1992-01-01

    A new multirate sampled-data control law structure is defined and a new parameter-optimization-based synthesis algorithm for that structure is introduced. The synthesis algorithm can be applied to multirate, multiple-input/multiple-output, sampled-data control laws having a prescribed dynamic order and structure, and a priori specified sampling/update rates for all sensors, processor states, and control inputs. The synthesis algorithm is applied to design two-input, two-output tip position controllers of various dynamic orders for a sixth-order, two-link robot arm model.

  15. A new multirate sampled-data control law structure and synthesis algorithm

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.; Yang, Gen-Sheng

    1991-01-01

    A new multirate sampled-data control law structure is defined and a new parameter-optimization-based synthesis algorithm for that structure is introduced. The synthesis algorithm can be applied to multirate, multiple-input multiple-output, sampled-data control laws having a prescribed dynamic order and structure, and a priori specified sampling/update rates for all sensors, processor states, and control inputs. The synthesis algorithm is applied to design two-input, two-output tip position controllers of various dynamic orders for a sixth-order, two-link robot arm model.

  16. Severe tibial bone loss in revision total knee replacement managed with structural femoral head allograft: a prospective case series from the Royal London Hospital.

    PubMed

    Lyall, H S; Sanghrajka, A; Scott, G

    2009-10-01

    Large tibial bone defects may cause problems at the time of revision total knee replacement. We report on 15 patients (15 knees) followed at a mean of 5.4 years (33-115 months) who underwent revision total knee replacement for severe tibial bone loss using shaped femoral head allograft and Freeman-Samuelson revision components (Zimmer, Winterthur, Switzerland). The mean American Knee Society Score pre-operatively was 22.7 points (0-45) increasing to a mean of 77.2 points (15-95) after operation. The survivorship for the series at 6 years was seven out of nine knees. One patient required an above knee amputation at 3.5 years, whilst another underwent a second revision TKR procedure at 3.4 years. Thirteen knees did not require further surgery and showed a mean time for allograft incorporation of 1.9 years (12-36 months) with no component migration. Severe tibial bone loss at the time of revision TKR surgery is a difficult problem to treat. Our case series demonstrates that when shaped femoral heads are used as structural allograft along with long stemmed components a successful result can be achieved.

  17. Inositolphosphoglycan mediators structurally related to glycosyl phosphatidylinositol anchors: synthesis, structure and biological activity.

    PubMed

    Martín-Lomas, M; Khiar, N; García, S; Koessler, J L; Nieto, P M; Rademacher, T W

    2000-10-02

    The preparation of the pseudopentasaccharide 1a, an inositol-phosphoglycan (IPG) that contains the conserved linear structure of glycosyl phosphatidylinositol anchors (GPI anchors), was carried out by using a highly convergent 2+3-block synthesis approach which involves imidate and sulfoxide glycosylation reactions. The preferred solution conformation of this structure was determined by using NMR spectroscopy and molecular dynamics simulations prior to carrying out quantitative structure--activity relationship studies in connection with the insulin signalling process. The ability of 1a to stimulate lipogenesis in rat adipocytes as well as to inhibit cAMP dependent protein kinase and to activate pyruvate dehydrogenase phosphatase was investigated. Compound 1a did not show any significant activity, which may be taken as a strong indication that the GPI anchors are not the precursors of the IPG mediators.

  18. Structure-borne sound: Structural vibrations and sound radiation at audio frequencies /2nd revised and enlarged edition/

    NASA Astrophysics Data System (ADS)

    Cremer, Lothar; Heckl, Manfred

    The fundamental principles of sound production and propagation in and from structures are examined analytically in an introductory textbook, and their design implications are considered. Chapters are devoted to the definition, measurement, and generation of structure-borne sound; wave types and characteristics; damping; impedances; attenuation; and sound radiation from structures. Diagrams, drawings, graphs, and tables of numerical data are provided.

  19. Synthesis modified structural and dielectric properties of semiconducting zinc ferrospinels

    NASA Astrophysics Data System (ADS)

    Kumari, N.; Kumar, V.; Singh, S. K.; Khasa, S.; Dahiya, M. S.

    2017-02-01

    The influence of preparation techniques on structural and dielectric properties of ZnCrxFe1-xO4 (x=0, 0.1 abbreviated as Z and ZC) ferrite nano-particles synthesized using chemical co-precipitation (CCP), sol-gel (SG) and solid state reaction (SS) techniques is discussed. XRD profiles are used to confirm the single phase spinel ferrite formation. TEM images indicate the change in size and shape of particles on changing either the composition or the synthesis methodology. The TEM micrograph of samples obtained through CCP shows uniform particle size formation compared to those obtained through SG and SS. Sample prepared through CCP possess porosity >70% making these materials suitable for sensing applications. The dielectric loss, dielectric constant and ac conductivity are analyzed as a function of frequency, temperature and composition using impedance spectroscopy. A universal dielectric behavior has been predicted through temperature and frequency variations of different parameters. Dielectric constant is found to possess highest value for sample synthesized through SG which marks the possibility of using the SG derived ferrospinels as microwave device components.

  20. Infant food applications of complex carbohydrates: Structure, synthesis, and function.

    PubMed

    Ackerman, Dorothy L; Craft, Kelly M; Townsend, Steven D

    2017-01-02

    Professional health bodies such as the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Department of Health and Human Services (HHS) recommend breast milk as the sole source of food during the first year of life. This position recognizes human milk as being uniquely suited for infant nutrition. Nonetheless, most neonates in the West are fed alternatives by 6 months of age. Although inferior to human milk in most aspects, infant formulas are able to promote effective growth and development. However, while breast-fed infants feature a microbiota dominated by bifidobacteria, the bacterial flora of formula-fed infants is usually heterogeneous with comparatively lower levels of bifidobacteria. Thus, the objective of any infant food manufacturer is to prepare a product that results in a formula-fed infant developing a breast-fed infant-like microbiota. The goal of this focused review is to discuss the structure, synthesis, and function of carbohydrate additives that play a role in governing the composition of the infant microbiome and have other health benefits.

  1. [Synthesis and crystalline structure of cis-monochloro(dimenthylsulfoxide)].

    PubMed

    Bentefrit, F; Viossat, B; Tomas, A; Nguyen Huy, D; Morgant, G

    2002-03-01

    The synthesis of cis-monochloro(dimethylsulfoxide)(metforminuro) platine(II) was investigated. It crystallizes in the monoclinic system, space group P 2(1)/c with Z=4. The cell parameters are: a=9.173(2); b=11.286( 2); c=12.556( 3) (A); b=99.69(2) degrees. The structure of this compound was refined to R=0.031 and wR=0.038 using 1461 independent reflexions with I>3 s(I). The platinum coordination is square planar, built up from one Cl, one O from the dimethylsulfoxide, and one bidentate chelating ligand (metforminure anion) via the two imine nitrogen atoms in cis position. The negative charge of the metforminure ligand ensures the electric neutrality in the complex. The crystal packing is characterized by four hydrogen bonds, one of which is bifurcated (involving Cl atom (intramolecular bonding) and O(i) (intermolecular bonding; symmetry code i: x, 3/2-y; 1/2+z).

  2. 78 FR 13911 - Proposed Revision to Design of Structures, Components, Equipment and Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ...,'' Section 3.7.3, ``Seismic Subsystem Analysis,'' Section 3.8.1, ``Concrete Containment,'' Section 3.8.3, ``Concrete And Steel Internal Structures of Steel Or Concrete Containments, ``Section 3.8.4, ``Other...

  3. Computer analysis of structural frameworks (2nd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Balfour, James A. D.

    The present book is intended to give engineering students and practicing engineers the background knowledge necessary to make safe and efficient use of commercial frame analysis programs. Fundamentals of structural behavior, the stiffness method, smultaneous linear equations, plane and space trusses, and plane frames are discussed. Attention is also given to grillages, space frames, structural dynamics, and the purchase and use of commercial and frame analysis programs.

  4. Mapping structures of the South China Sea; a synthesis

    NASA Astrophysics Data System (ADS)

    Pubellier, Manuel; Savva, Dimitri; Aurelio, Mario; Yan, Qiu; Phach Phung, Van; Franke, Dieter; Rahman, Hadi A.; Mansor, Yazid M.; Auxiètre, Jean Luc; Meresse, Florian; Delescluse, Matthias; Pichot, Thibaud; Chan, Lung Sang; Le Gal, Virginie; Xin, Nie

    2015-04-01

    The South China Sea margin has been the focus of scientific interest in the past decade including ODP and IODP drilling, oil and gas exploration, and projects from several international teams onshore and offshore. The South China Sea, because of its narrow V shape oceanic crust, the wide extension of its rifted continental crust, and the various styles of rifting is an interesting playground to study the formation of passive margins. We present a synthesis of the main characteristics of the SCS on a structural map focused on the Late Mesozoic and Cenozoic features. The basement, similar in China, Vietnam and part of the western Philippines is undifferentiated. The Mesozoic location of the area was on the upper plate of a subduction zone, resulting in an impressive coverage of Cretaceous granites sometimes separated by narrow Cretaceous molasse basins. These granitic bodies, widespread offshore in the extended crust conditioned the location of the extension via large detachments and normal faults; later cut by steeper faults. The geometries of the faults vary from E-W to NE-SW indicating that the rifting underwent several stages with different stretching directions and a varying degree of extension which ultimately exhumed the mantle. Some faults are low angle detachments and therefore surround the granitic/metamorphic basement structures with an E-W general trend. Platform and reef carbonates occupy some of the bathymetric highs and developed mainly during Late Oligocene to Mid Miocene times and during Late Miocene times. The map also illustrates the coverage of the different units of the NW Borneo wedge, which actually develops offshore in the SE SCS and shifts to the NW of the Sulu Sea. Onshore Borneo, the sub-aerial conditions for the NW Borneo wedge resulted in intense erosion and deltas formation.

  5. Thiaminylated adenine nucleotides. Chemical synthesis, structural characterization and natural occurrence.

    PubMed

    Frédérich, Michel; Delvaux, David; Gigliobianco, Tiziana; Gangolf, Marjorie; Dive, Georges; Mazzucchelli, Gabriel; Elias, Benjamin; De Pauw, Edwin; Angenot, Luc; Wins, Pierre; Bettendorff, Lucien

    2009-06-01

    Thiamine and its three phosphorylated derivatives (mono-, di- and triphosphate) occur naturally in most cells. Recently, we reported the presence of a fourth thiamine derivative, adenosine thiamine triphosphate, produced in Escherichia coli in response to carbon starvation. Here, we show that the chemical synthesis of adenosine thiamine triphosphate leads to another new compound, adenosine thiamine diphosphate, as a side product. The structure of both compounds was confirmed by MS analysis and 1H-, 13C- and 31P-NMR, and some of their chemical properties were determined. Our results show an upfield shifting of the C-2 proton of the thiazolium ring in adenosine thiamine derivatives compared with conventional thiamine phosphate derivatives. This modification of the electronic environment of the C-2 proton might be explained by a through-space interaction with the adenosine moiety, suggesting U-shaped folding of adenosine thiamine derivatives. Such a structure in which the C-2 proton is embedded in a closed conformation can be located using molecular modeling as an energy minimum. In E. coli, adenosine thiamine triphosphate may account for 15% of the total thiamine under energy stress. It is less abundant in eukaryotic organisms, but is consistently found in mammalian tissues and some cell lines. Using HPLC, we show for the first time that adenosine thiamine diphosphate may also occur in small amounts in E. coli and in vertebrate liver. The discovery of two natural thiamine adenine compounds further highlights the complexity and diversity of thiamine biochemistry, which is not restricted to the cofactor role of thiamine diphosphate.

  6. Uncertainty Modeling for Structural Control Analysis and Synthesis

    NASA Technical Reports Server (NTRS)

    Campbell, Mark E.; Crawley, Edward F.

    1996-01-01

    The development of an accurate model of uncertainties for the control of structures that undergo a change in operational environment, based solely on modeling and experimentation in the original environment is studied. The application used throughout this work is the development of an on-orbit uncertainty model based on ground modeling and experimentation. A ground based uncertainty model consisting of mean errors and bounds on critical structural parameters is developed. The uncertainty model is created using multiple data sets to observe all relevant uncertainties in the system. The Discrete Extended Kalman Filter is used as an identification/parameter estimation method for each data set, in addition to providing a covariance matrix which aids in the development of the uncertainty model. Once ground based modal uncertainties have been developed, they are localized to specific degrees of freedom in the form of mass and stiffness uncertainties. Two techniques are presented: a matrix method which develops the mass and stiffness uncertainties in a mathematical manner; and a sensitivity method which assumes a form for the mass and stiffness uncertainties in macroelements and scaling factors. This form allows the derivation of mass and stiffness uncertainties in a more physical manner. The mass and stiffness uncertainties of the ground based system are then mapped onto the on-orbit system, and projected to create an analogous on-orbit uncertainty model in the form of mean errors and bounds on critical parameters. The Middeck Active Control Experiment is introduced as experimental verification for the localization and projection methods developed. In addition, closed loop results from on-orbit operations of the experiment verify the use of the uncertainty model for control analysis and synthesis in space.

  7. Brazilian version of the Structured Interview for Disorders of Extreme Stress - Revised (SIDES-R): adaptation and validation process.

    PubMed

    Camargo, Jessica; Kluwe-Schiavon, Bruno; Sanvicente-Vieira, Breno; Levandowski, Mateus Luz; Grassi-Oliveira, Rodrigo

    2013-12-01

    Posttraumatic stress disorder (PTSD) contemplates the impact of acute traumatic events, but the literature indicates that this is not true for chronic exposure to stress. In this sense, the category disorders of extreme stress not otherwise specified (DESNOS) has been proposed to characterize the behavior and cognitive alterations derived from exposure to continuous early life stress. The Structured Interview for Disorders of Extreme Stress - Revised (SIDES-R) was developed to investigate and measure DESNOS. Considering the lack of instruments designed to assess DESNOS, especially in Brazil, the aim of this study was to translate, adapt, and validate the contents of SIDES-R to Brazilian Portuguese (SIDES-R-BR). The original interview was subjected to translation, back-translation, semantic equivalence and conceptual correspondence analyses by naive and specialized judges, respectively, an acceptability trial, and inter-rater validity analysis. The interview underwent semantic and structural adaptations considering the Brazilian culture. The final version, SIDES-R-BR, showed a mean understanding score of 4.98 on a 5-point verbal rating scale, in addition to a kappa coefficient of 0.853. SIDES-R-BR may be a useful tool in the investigation of DESNOS and contributes a valuable input to clinical research in Brazil. The availability of the instrument allows to test symptoms with adequate reliability, as verified by the kappa coefficient and translation steps.

  8. Structure of the Children's Revised Impact of Event Scale (CRIES) with children and adolescents exposed to debris flood.

    PubMed

    Chen, Zhenggen; Zhang, Yuqing; Liu, Zhengkui; Liu, Yin; Dyregrov, Atle

    2012-01-01

    PTSD symptoms were pervasive among children and adolescents after experiencing or exposure to traumatic events. Screening and diagnosis of PTSD symptoms is crucial in trauma-related research and practice. The 13-item Children's Revised Impact of Event Scale (CRIES) has been demonstrated to be a valid and reliable tool to achieve this goal. This study was designed to examine the psychometric properties of the 13-item CRIES in a sample of Chinese debris flood victims. A total of 268 participants (145 girls, 123 boys) aged 8-18 years were recruited from an integral part of a service oriented project, supported by the Institute of Psychology, Chinese Academy of Sciences following the debris flood. The participants were given the 13-item CRIES 3 months after the debris flood. The results of confirmatory factor analysis indicated that a two-factor structure (intrusion+arousal vs avoidance) emerged as the model best fit in total sample, boys and girls subsamples, respectively. The scale was also demonstrated to have good internal consistency (Cronbach's alpha = 0.83). The study confirmed the good psychometric properties of the CRIES and its' applicability to Chinese children and adolescents. Moreover, these findings imply that the CRIES factor structure is stable across age, gender, and different types of trauma.

  9. Structure, Mechanics and Synthesis of Nanoscale Carbon and Boron Nitride

    NASA Astrophysics Data System (ADS)

    Rinaldo, Steven G.

    This thesis is divided into two parts. In Part I, we examine the properties of thin sheets of carbon and boron nitride. We begin with an introduction to the theory of elastic sheets, where the stretching and bending modes are considered in detail. The coupling between stretching and bending modes is thought to play a crucial role in the thermodynamic stability of atomically-thin 2D sheets such as graphene. In Chapter 2, we begin by looking at the fabrication of suspended, atomically thin sheets of graphene. We then study their mechanical resonances which are read via an optical transduction technique. The frequency of the resonators was found to depend on their temperature, as was their quality factor. We conclude by offering some interpretations of the data in terms of the stretching and bending modes of graphene. In Chapter 3, we look briefly at the fabrication of thin sheets of carbon and boron nitride nanotubes. We examine the structure of the sheets using transmission and scanning electron microscopy (TEM and SEM, respectively). We then show a technique by which one can make sheets suspended over a trench with adjustable supports. Finally, DC measurements of the resistivity of the sheets in the temperature range 600 -- 1400 C are presented. In Chapter 4, we study the folding of few-layer graphene oxide, graphene and boron nitride into 3D aerogel monoliths. The properties of graphene oxide are first considered, after which the structure of graphene and boron nitride aerogels is examined using TEM and SEM. Some models for their structure are proposed. In Part II, we look at synthesis techniques for boron nitride (BN). In Chapter 5, we study the conversion of carbon structures of boron nitride via the application of carbothermal reduction of boron oxide followed by nitridation. We apply the conversion to a wide variety of morphologies, including aerogels, carbon fibers and nanotubes, and highly oriented pyrolytic graphite. In the latter chapters, we look at the

  10. Synthesis, Structure, and Properties of New Ternary Calcium Nitrides

    NASA Astrophysics Data System (ADS)

    Chern, Ming-Yau

    The discussion of the chemistry of nitrides, its relationship with oxides, especially the high T _{rm c} oxides, and ways to approach new nitrides is introduced in Chapter 1. Chapter 2 describes the synthesis and physical properties of a new metallic ternary nitride, CaNiN, prepared by the reaction of Ca_3N _2 and Ni in N_2 gas at 1000^circC. The structure is a simple one with all atoms occupying fixed special positions, yet it features interesting and uncommon--Ni -N-Ni-N--linear chains. Although Ni usually has a 2+ or 3+ formal oxidation state in oxides and sulfides, it has the unusual oxidation state of 1+ in CaNiN. In Chapter 3, a new ternary nitride Ca _2ZnN_2, prepared by the reaction of Ca_3N _2 and Zn in N_2 gas at 680^circC is described. The structure, refined by Rietveld profile analysis of x-ray powder diffraction data, is tetragonal (I 4/m m m) with a = 3.5835(4)A, c = 12.6583(7)A, and Z = 2. It features condensed nitrogen-centered metal octahedra and an unusual linear coordination of Zn by two nitrogen atoms. Conductivity and magnetic measurements show that Ca_2 ZnN_2 is insulating and diamagnetic. A family of anti-perovskite nitrides of the formula Ca_3MN, where M is a Group IV or a Group V element, is reported in Chapter 4. Ca _3BiN is the first one synthesized in this family. It is semiconducting and diamagnetic as expected from the closed shell electronic configuration of each species, i.e. Bi^{3-}, N^{3-}, and Ca ^{2+}. The anionic bismuth suggests that it can be subsituted for by other trivalent anions Sb^{3-}, As^ {3-}, and P^{3-} . The structure of Ca_3AsN and Ca_3PN are actually distorted from the cubic cell at room temperature because As ^{3-} and P^{3 -} are smaller than Bi^{3 -}. Structural phase transitions were also observed at high temperatures by magnetic susceptibility measurements in those two phases. In the last chapter, Chapter 6, the use and design of several apparatuses in characterizing the compounds mentioned above are presented

  11. Scar revision

    MedlinePlus

    ... corrects skin changes (disfigurement) caused by an injury, wound, poor healing, or previous surgery. Description Scar tissue forms as ... stiffening of the joint, you may need physical therapy after surgery. Apply sunscreen to keep sunlight from permanently ... Keloid revision; Hypertrophic scar revision; ...

  12. America Revising.

    ERIC Educational Resources Information Center

    Marty, Myron

    1982-01-01

    Reviews Frances FitzGerald's book, "America Revised," and discusses FitzGerald's critique of recent revisions in secondary-level U.S. history textbooks. The author advocates the implementation of a core curriculum for U.S. history which emphasizes political and local history. (AM)

  13. Structural Design Requirements and Factors of Safety for Spaceflight Hardware: For Human Spaceflight. Revision A

    NASA Technical Reports Server (NTRS)

    Bernstein, Karen S.; Kujala, Rod; Fogt, Vince; Romine, Paul

    2011-01-01

    This document establishes the structural requirements for human-rated spaceflight hardware including launch vehicles, spacecraft and payloads. These requirements are applicable to Government Furnished Equipment activities as well as all related contractor, subcontractor and commercial efforts. These requirements are not imposed on systems other than human-rated spacecraft, such as ground test articles, but may be tailored for use in specific cases where it is prudent to do so such as for personnel safety or when assets are at risk. The requirements in this document are focused on design rather than verification. Implementation of the requirements is expected to be described in a Structural Verification Plan (SVP), which should describe the verification of each structural item for the applicable requirements. The SVP may also document unique verifications that meet or exceed these requirements with NASA Technical Authority approval.

  14. A revised version of the transfer matrix method to analyze one-dimensional structures

    NASA Technical Reports Server (NTRS)

    Nitzsche, F.

    1983-01-01

    A new and general method to analyze both free and forced vibration characteristics of one-dimensional structures is discussed in this paper. This scheme links for the first time the classical transfer matrix method with the recently developed integrating matrix technique to integrate systems of differential equations. Two alternative approaches to the problem are presented. The first is based upon the lumped parameter model to account for the inertia properties of the structure. The second releases that constraint allowing a more precise description of the physical system. The free vibration of a straight uniform beam under different support conditions is analyzed to test the accuracy of the two models. Finally some results for the free vibration of a 12th order system representing a curved, rotating beam prove that the present method is conveniently extended to more complicated structural dynamics problems.

  15. Total synthesis of the putative structure of the proposed Banyasin A

    PubMed Central

    Gao, Xuguang; Ren, Qi; Choi, Sun; Xu, Zhengshuang; Ye, Tao

    2015-01-01

    The first total synthesis of four possible isomers of a molecule possessing the configuration proposed for Banyasin A is described. The structure synthesized appears to be different from that of the natural product. PMID:25853121

  16. Internal Structure and Clinical Utility of the Anxiety Control Questionnaire-Revised (ACQ-R) Spanish Version.

    PubMed

    Osma, Jorge; Barrada, Juan Ramón; García-Palacios, Azucena; Navarro-Haro, María; Aguilar, Alejandra

    2016-10-03

    Perceived control has shown predictive value for anxiety severity symptoms as well as cognitive-behavior therapy outcomes. The most commonly used measure of perceived control is the Anxiety Control Questionnaire (ACQ), and more recently the ACQ Revised (ACQ-R). However, both questionnaires have shown structural inconsistencies among several studies. Also, although the ACQ and ACQ-R seem to be multidimensional instruments, a single total score have been commonly used. This study examined the internal structure of the ACQ-R Spanish version using exploratory factor and exploratory bi-factor analysis in a sample of 382 college students and 52 people diagnosed of panic disorder (with or without agoraphobia). Also, in this study we assessed the preliminary diagnostic value of the ACQ-R scores. The results indicated that the ACQ-R Spanish version structure consisted of two factors: one related with perceived control of internal emotional reactions (Emotion Control) and another related with perceived control of external events (Threat and Stress Control). Both specific factors can be adequately summarized by a general factor (General Anxiety Perception of Control; CFI = .973, TLI = .954, RMSEA = .039; p = .002), which accounted for 70% of the common explained variance. The correlations between the ACQ-R scores and with variables like anxiety (r = -.66) or anxiety sensitivity (r = -.50) presented the expected pattern of results. Either the two dimensions structure or the total score have proved to be a good tool to distinguish between participants with panic disorder and non-clinical samples (area under the curve = 0.79).

  17. Total Synthesis of Pinnatoxins A and G and Revision of the Mode of Action of Pinnatoxin A

    PubMed Central

    Araoz, Romulo; Servent, Denis; Molgó, Jordi; Iorga, Bogdan I.; Fruchart-Gaillard, Carole; Benoit, Evelyne; Gu, Zhenhua; Stivala, Craig; Zakarian, Armen

    2012-01-01

    Pinnatoxins belong to an emerging class of potent marine toxins of the cyclic imine group. Detailed studies of their biological effects have been impeded by unavailability of the complex natural product from natural sources. This work describes the development of a robust, scalable synthetic sequence relying on a convergent strategy that delivered a sufficient amount of the toxin for detailed biological studies and its commercialization for use by other research groups and regulatory agencies. A central transformation in the synthesis is the highly diastereoselective Ireland–Claisen rearrangement of a complex α,α-disubstituted allylic ester based on a unique mode for stereoselective enolization through a chirality match between the substrate and the lithium amide base. With synthetic pinnatoxin A, a detailed study has been performed that provides conclusive evidence for its mode of action as a potent inhibitor of nicotinic acetylcholine receptors selective for the human neuronal α7 subtype. The comprehensive electrophysiological, biochemical, and computational studies support the view that the spiroimine subunit of pinnatoxins is critical for blocking nicotinic acetylcholine receptor subtypes, as evidenced by analyzing the effect of a synthetic analogue of pinnatoxin A containing an open form of the imine ring. Our studies have paved the way for the production of certified standards to be used for mass-spectrometric determination of these toxins in marine matrices and for the development of tests to detect these toxins in contaminated shellfish. PMID:21644584

  18. Revised structural phase transitions in the archetype KMnF3 perovskite crystal

    NASA Astrophysics Data System (ADS)

    Kapusta, Joanna; Daniel, Philippe; Ratuszna, Alicja

    1999-06-01

    Reinvestigation of the structural and vibrational properties of the typical perovskite KMnF3, exhibiting two antiferrodistortive structural phase transitions, was performed using x-ray powder diffraction and Raman spectroscopy in the range between 30 and 300 K. The x-ray-diffraction work has unambiguously shown that a monoclinic distortion (ra-b+c- tilt system P21/m space group) is observed at low temperature below TC2=91 K. This result corresponds with the Raman temperature study which shows that this transition, in spite of its first-order character, can be associated with a group-subgroup relation between tetragonal and monoclinic symmetries. Additionally, existence of a large structural disorder far above the cubic to tetragonal transition (TC1=186 K) is suggested by the two following experimental indications: (i) persistence of hard modes of the tetragonal phase in the cubic symmetry, and (ii) existence of Raman broad bands in normally inactive ideal cubic phase, which are interpreted by the folding of the whole phonons branches of the cubic Brillouin zone. This last observation allows us to follow the evolution of the cubic R'15 soft mode versus temperature, based only on the Raman-scattering data, in full agreement with previous inelastic neutron data. The results of Raman investigations into KMnF3 are discussed in more general framework of structural disorder in perovskite systems which exhibit anisotropic correlation between octahedra.

  19. 78 FR 59732 - Revisions to Design of Structures, Components, Equipment, and Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-27

    ..., ``Seismic Subsystem Analysis,'' Section 3.8.1, ``Concrete Containment,'' Section 3.8.3, ``Concrete and Steel Internal Structures of Steel or Concrete Containments,'' Section 3.8.4, ``Other Seismic Category I... Analysis,'' (Accession No. ML13198A239); Section 3.8.1, ``Concrete Containment,'' (Accession...

  20. The Factorial Structure of the Revised Collett--Lester Fear of Death Scale

    ERIC Educational Resources Information Center

    Lester, David

    2004-01-01

    In a study of 144 college students, the factorial structure of the Collett?Lester Fear of Death Scale matched the face content of the subscales quite closely, ameliorating the criticism of the scale by R. A. Neimeyer et al. (2003).

  1. Mercy Mission and Transformative Change: Evaluation of a Revised Governance Structure

    ERIC Educational Resources Information Center

    Affenito, Sandra G.; Artz, Judy; Carlson, Vivian

    2014-01-01

    The University of St. Joseph, a Mercy institution, was founded during the Great Depression to provide women a gateway to higher education for careers in fields that would serve the well-being of society. Recently, the institution has undergone changes to modernize its organizational structure. Consistent with its commitment to educate people of…

  2. Mercy Mission and Transformative Change: Evaluation of a Revised Governance Structure

    ERIC Educational Resources Information Center

    Affenito, Sandra G.; Artz, Judy; Carlson, Vivian

    2014-01-01

    The University of St. Joseph, a Mercy institution, was founded during the Great Depression to provide women a gateway to higher education for careers in fields that would serve the well-being of society. Recently, the institution has undergone changes to modernize its organizational structure. Consistent with its commitment to educate people of…

  3. Synthesis of the Bycroft-Gowland structure of micrococcin P1.

    PubMed

    Ciufolini, M A; Shen, Y C

    1999-12-02

    [formula: see text] We describe the chemical synthesis of the accepted structure of micrococcin P1, a member of the thiostrepton group of antibiotics, and we show that this architecture does not correspond to that of the natural product. Methods developed during the present study should greatly facilitate ongoing efforts centering on the determination of the actual structure of microccin P1, in addition to being applicable to the synthesis of more complex thiostrepton congeners.

  4. Structural allograft and cemented long-stem prosthesis for complex revision hip arthroplasty: use of a trochanteric claw plate improves final hip function

    PubMed Central

    Lemoine, Camille Thevenin; Kerboull, Marcel; Courpied, Jean Pierre

    2007-01-01

    Extensive bone loss raises formidable challenges in total hip revision. The aim of this study was to evaluate the results of reconstruction using a cemented long-stem and massive structural allograft implanted in a filleted proximal femur, with and without the use of a trochanteric claw plate. Between 1988 and 2001, 44 revisions were performed in 42 patients. After a transtrochanteric approach, the femur was cut longitudinally. A long, cemented Charnley-type prosthesis was used, and flaps of the residual femur were folded around the allograft. The greater trochanter was reinserted with wires in all revisions, and with both wires and a claw plate in 20 revisions. Mean follow-up was 7.15 years (range: 3–16); seven patients, died and four were lost to follow-up. The follow-up exceeded five years in 34 patients. The major complication was nonunion of the greater trochanter, which occurred in 25 cases. Six dislocations, one recurrence of infection, two mechanical loosening, and two fractures below the stem were also recorded. The use of a trochanteric claw plate significantly improved final hip stability, even in patients with nonunion. Femoral reconstruction with a massive structural allograft is reliable and long-lived, and serious complications and long-term resorption are uncommon. The use of a trochanteric claw plate significantly improves final hip stability. Level of evidence: Therapeutic study, level III (retrospective comparative study). PMID:18008098

  5. Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures

    NASA Technical Reports Server (NTRS)

    Rodriquez, Gary

    2013-01-01

    The Moonraker Excavator and other tools under development for use on the Moon, Mars, and asteroids will be employed to construct a number of civil engineering projects and to mine the soil. Mounds of loose soil will be subject to the local transport mechanisms plus artificial mechanisms such as blast effects from landers and erosion from surface vehicles. Some of these structures will require some permanence, with a minimum of maintenance and upkeep. Combustion Synthesis (CS) is a family of processes and techniques whereby chemistry is used to transform materials, often creating flame in a hard vacuum. CS can be used to stabilize civil engineering works such as berms, habitat shielding, ramps, pads, roadways, and the like. The method is to unroll thin sheets of CS fabric between layers of regolith and then fire the fabric, creating a continuous sheet of crusty material to be interposed among layers of loose regolith. The combination of low-energy processes, ISRU (in situ resource utilization) excavator, and CS fabrics, seems compelling as a general method for establishing structures of some permanence and utility, especially in the role of robotic missions as precursors to manned exploration and settlement. In robotic precursory missions, excavator/ mobility ensembles mine the Lunar surface, erect constructions of soil, and dispense sheets of CS fabrics that are covered with layers of soil, fired, and then again covered with layers of soil, iterating until the desired dimensions and forms are achieved. At the base of each berm, for example, is a shallow trench lined with CS fabric, fired and filled, mounded, and then covered and fired, iteratively to provide a footing against lateral shear. A larger trench is host to a habitat module, backfilled, covered with fabric, covered with soil, and fired. Covering the applied CS fabric with layers of soil before firing allows the resulting matrix to incorporate soil both above and below the fabric ply into the fused layer

  6. Using the Dempster-Shafer theory of evidence with a revised lattice structure for activity recognition.

    PubMed

    Liao, Jing; Bi, Yaxin; Nugent, Chris

    2011-01-01

    This paper explores a sensor fusion method applied within smart homes used for the purposes of monitoring human activities in addition to managing uncertainty in sensor-based readings. A three-layer lattice structure has been proposed, which can be used to combine the mass functions derived from sensors along with sensor context. The proposed model can be used to infer activities. Following evaluation of the proposed methodology it has been demonstrated that the Dempster-Shafer theory of evidence can incorporate the uncertainty derived from the sensor errors and the sensor context and subsequently infer the activity using the proposed lattice structure. The results from this study show that this method can detect a toileting activity within a smart home environment with an accuracy of 88.2%.

  7. Sliding and Rocking of Unanchored Components and Structures: Chapter 7.6 ASCE 4 Revision 2

    SciTech Connect

    S. R. Jensen

    2011-04-01

    Chapter 7.6 of ASCE 4-Rev 2, Seismic Analysis of Safety-Related Nuclear Structures: Standard and Commentary, provides updated guidance for analysis of rocking and sliding of unanchored structures and components subjected to seismic load. This guidance includes provisions both for simplified approximate energy-based approaches, and for detailed probabilistic time history analysis using nonlinear methods. Factors to be applied to the analytical results are also provided with the intent of ensuring achievement of the 80% non-exceedence probability target of the standard. The present paper surveys the published literature supporting these provisions. The results of available testing and analysis are compared to results produced by both simplified and probabilistic approaches. In addition, adequacy of the standard's provisions for analysis methods and factors is assessed. A comparison is made between the achieved level of conservatism and the standard's non-exceedence probability target.

  8. Revised domain structure of ulvan lyase and characterization of the first ulvan binding domain

    PubMed Central

    Melcher, Rebecca L. J.; Neumann, Marten; Fuenzalida Werner, Juan Pablo; Gröhn, Franziska; Moerschbacher, Bruno M.

    2017-01-01

    Biomass waste products from green algae have recently been given new life, as these polysaccharides have potential applications in industry, agriculture, and medicine. One such polysaccharide group called ulvans displays many different, potentially useful properties that arise from their structural versatility. Hence, performing structural analyses on ulvan is crucial for future applications. However, chemical reaction–based analysis methods cannot fully characterize ulvan and tend to alter its structure. Thus, better methods require well-characterized ulvan-degrading enzymes. Therefore, we analysed a previously sequenced ulvan lyase (GenebankTM reference number JN104480) and characterized its domains. We suggest that the enzyme consists of a shorter than previously described catalytic domain, a newly identified substrate binding domain, and a C-terminal type 9 secretion system signal peptide. By separately expressing the two domains in E. coli, we confirmed that the binding domain is ulvan specific, having higher affinity for ulvan than most lectins for their ligands (affinity constant: 105 M−1). To our knowledge, this is the first description of an ulvan-binding domain. Overall, identifying this new binding domain is one step towards engineering ulvan enzymes that can be used to characterize ulvan, e.g. through enzymatic/mass spectrometric fingerprinting analyses, and help unlock its full potential. PMID:28327560

  9. An Exploration of the Four-Factor Structure of the Drinking Motives Questionnaire-Revised Among Undergraduate Students in China

    PubMed Central

    Sun, Li; Windle, Michael; Thompson, Nancy J.

    2016-01-01

    Background College drinking has become a significant health issue in China; the current study addressed the gap that no prior research has investigated drinking motives among Chinese undergraduate students. Objectives This study aimed to replicate the four-factor structure of the Drinking Motives Questionnaire-Revised (DMQ-R) reported for Western populations. Additionally, the relationships between drinking motives and alcohol use were investigated. Methods In 2012, 436 participants (mean age = 20.49 and SD = 1.49; 50% male) recruited from a college in China completed a self-administered survey in their classroom setting. Drinking motives were measured by the Chinese version of the DMQ-R; three indicators of alcohol use were assessed. Factor analysis was conducted to examine the factor structure of the DMQ-R, followed by regression analysis to investigate the associations between drinking motives and alcohol-related outcomes. Results Confirmatory factor analysis failed to replicate the measurement model tested, but exploratory factor analysis identified a similar four-dimensional factor structure. Reliability and convergent and discriminant validity of the four factors were acceptable. The results also showed that social motives were related to alcohol use and heavy drinking; conformity motives were related to alcohol use and alcohol-related problems. Enhancement motives were the strongest correlates of alcohol use; coping motives were the strongest correlates of heavy drinking and alcohol-related problems. Conclusions/Importance The DMQ-R was a reliable and valid scale measuring four types of drinking motives among Chinese college students. Findings suggested that the motivational model of alcohol use may apply to studying college drinking in China. PMID:26576670

  10. An Exploration of the Four-Factor Structure of the Drinking Motives Questionnaire-Revised Among Undergraduate Students in China.

    PubMed

    Sun, Li; Windle, Michael; Thompson, Nancy J

    2015-01-01

    College drinking has become a significant health issue in China; the current study addressed the gap that no prior research has investigated drinking motives among Chinese undergraduate students. This study aimed to replicate the four-factor structure of the Drinking Motives Questionnaire-Revised (DMQ-R) reported for Western populations. Additionally, the relationships between drinking motives and alcohol use were investigated. In 2012, 436 participants (mean age = 20.49 and SD = 1.49; 50% male) recruited from a college in China completed a self-administered survey in their classroom setting. Drinking motives were measured by the Chinese version of the DMQ-R; three indicators of alcohol use were assessed. Factor analysis was conducted to examine the factor structure of the DMQ-R, followed by regression analysis to investigate the associations between drinking motives and alcohol-related outcomes. Confirmatory factor analysis failed to replicate the measurement model tested, but exploratory factor analysis identified a similar four-dimensional factor structure. Reliability and convergent and discriminant validity of the four factors were acceptable. The results also showed that social motives were related to alcohol use and heavy drinking; conformity motives were related to alcohol use and alcohol-related problems. Enhancement motives were the strongest correlates of alcohol use; coping motives were the strongest correlates of heavy drinking and alcohol-related problems. The DMQ-R was a reliable and valid scale measuring four types of drinking motives among Chinese college students. Findings suggested that the motivational model of alcohol use may apply to studying college drinking in China.

  11. Structural asymmetry of the terminal catalytic complex in selenocysteine synthesis.

    PubMed

    French, Rachel L; Gupta, Nirupama; Copeland, Paul R; Simonović, Miljan

    2014-10-17

    Selenocysteine (Sec), the 21(st) amino acid, is synthesized from a serine precursor in a series of reactions that require selenocysteine tRNA (tRNA(Sec)). In archaea and eukaryotes, O-phosphoseryl-tRNA(Sec):selenocysteinyl-tRNA(Sec) synthase (SepSecS) catalyzes the terminal synthetic reaction during which the phosphoseryl intermediate is converted into the selenocysteinyl moiety while being attached to tRNA(Sec). We have previously shown that only the SepSecS tetramer is capable of binding to and recognizing the distinct fold of tRNA(Sec). Because only two of the four tRNA-binding sites were occupied in the crystal form, a question was raised regarding whether the observed arrangement and architecture faithfully recapitulated the physiologically relevant ribonucleoprotein complex important for selenoprotein formation. Herein, we determined the stoichiometry of the human terminal synthetic complex of selenocysteine by using small angle x-ray scattering, multi-angle light scattering, and analytical ultracentrifugation. In addition, we provided the first estimate of the ratio between SepSecS and tRNA(Sec) in vivo. We show that SepSecS preferentially binds one or two tRNA(Sec) molecules at a time and that the enzyme is present in large molar excess over the substrate tRNA in vivo. Moreover, we show that in a complex between SepSecS and two tRNAs, one enzyme homodimer plays a role of the noncatalytic unit that positions CCA ends of two tRNA(Sec) molecules into the active site grooves of the other, catalytic, homodimer. Finally, our results demonstrate that the previously determined crystal structure represents the physiologically and catalytically relevant complex and suggest that allosteric regulation of SepSecS might play an important role in regulation of selenocysteine and selenoprotein synthesis. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Synthesis and crystal structure characterisation of sodium neptunate compounds

    NASA Astrophysics Data System (ADS)

    Smith, A. L.; Raison, P. E.; Konings, R. J. M.

    2011-06-01

    The present work reports studies of the chemical reactions between neptunium dioxide and sodium oxide either in the presence of oxygen or inert gas (Ar), leading to compounds with hexavalent, heptavalent or pentavalent/tetravalent neptunium, respectively. Solid state synthesis with different NpO 2/Na 2O ratios led to the following polycrystalline compounds: Na 2Np 2O 7 monoclinic (P12 11), α-Na 2NpO 4 orthorhombic (Pbam), β-Na 2NpO 4 orthorhombic (Pbca), β-Na 4NpO 5 tetragonal (I4/mmm), Na 5NpO 6 monoclinic (C2/m) and a cubic compound (Fm-3m) that could either be Na 3NpO 4 or Na 4NpO 4. The crystal structures of the α-Na 2NpO 4 and Na 2Np 2O 7 compounds were refined by Rietveld analysis. Evolution of the cell parameters of α-Na 2NpO 4 was also followed as a function of temperature up to 1273 K by X-ray diffraction. The corresponding linear thermal expansion coefficients along the different axis were determined: αa = 41.3 × 10 -6 K -1, αb = 35.0 × 10 -6 K -1, αc ˜ 0 K -1. From the high temperature X-ray diffraction experiment it was also possible to evidence formation of diverse phases at different temperatures and to review parts of the Na-Np-O system.

  13. Barium borohydride chlorides: synthesis, crystal structures and thermal properties.

    PubMed

    Grube, Elisabeth; Olesen, Cathrine H; Ravnsbæk, Dorthe B; Jensen, Torben R

    2016-05-10

    Here we report the synthesis, mechanism of formation, characterization and thermal decomposition of new barium borohydride chlorides prepared by mechanochemistry and thermal treatment of MBH4-BaCl2, M = Li, Na or K in ratios 1 : 1 and 1 : 2. Initially, orthorhombic barium chloride, o-BaCl2 transforms into o-Ba(BH4)xCl2-x, x ∼ 0.15. Excess LiBH4 leads to continued anion substitution and a phase transformation into hexagonal barium borohydride chloride h-Ba(BH4)xCl2-x, which accommodates higher amounts of borohydride, possibly x ∼ 0.85 and resembles h-BaCl2. Thus, two solid solutions are in equilibrium during mechano-chemical treatment of LiBH4-BaCl2 (1 : 1) whereas LiBH4-BaCl2 (2 : 1) converts to h-Ba(BH4)0.85Cl1.15. Upon thermal treatment at T > ∼200 °C, h-Ba(BH4)0.85Cl1.15 transforms into another orthorhombic barium borohydride chloride compound, o-Ba(BH4)0.85Cl1.15, which is structurally similar to o-BaBr2. The samples with M = Na and K have lower reactivity and form o-Ba(BH4)xCl2-x, x ∼ 0.1 and a solid solution of sodium chloride dissolved in solid sodium borohydride, Na(BH4)1-xClx, x = 0.07. The new compounds and reaction mechanisms are investigated by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mass spectroscopy (MS) and temperature programmed photographic analysis (TPPA).

  14. DAA modal analysis for parametric investigations of fluid-structure interaction in underwater shock. Revision 2

    SciTech Connect

    Ginsberg, J.H.; Rosenkilde, C.E.

    1985-02-01

    A program was initiated several years ago with the goal of developing a simulation of the underwater shock response of submarines. This capability was to be employed for systems analysis studies of a variety of tactical parameters, especially the orientation of the shock wave relative to the structure. It was deemed to be acceptable to develop generic analytical models that avoided the details of specific structures, and the number of degrees of freedom was limited by the need for computational efficiency. The present paper shows how these objectives were met by using the modal expansion version of the doubly asymptotic approximation. This technique is implemented in a modular form that permits progressive enhancements of a basic model. The concept is to partition the system into substructures that are not inertially coupled. Based on these concepts three varients on a basic model are described; each modification provides the capability to evaluate different aspects of the system. The basic model consists of a rigid cylinder capped by hemispheres which is subjected to a shock wave arriving from an arbitrary heading angle. The REFLECT model extends this fundamental model to treat multiple shock waves associated with reflections from the surface and bottom. This analysis employs a vectorial superposition of the CAPS response for each incident wave. In order to assess the importance of an internal dead load, such as a reactor, the CAPS model was extended. The new version includes a large internal mass suspended from the cylinder by four springs that give equivalent axial, transverse and rotational suspension stiffnesses. The center of mass of this dead load can be located arbitrarily along the axis of symmetry of the cylinder. The TDEF model of structural deformation was the last to be developed.

  15. Kermesite, Sb2S2O: crystal structure revision and order-disorder interpretation.

    PubMed

    Hybler, Jiří; Durovič, Slavomil

    2013-12-01

    Kermesite, Sb2S2O, is a desymmetrized order-disorder (OD) structure of layers. Two data sets were recorded using twinned crystals from Pezinok, Slovakia (named as Pz21, Pz24). The primitive unit cell is triclinic, P1, Z = 4, cell parameters are a = 8.1416 (3), b = 10.6968 (3), c = 5.7835 (2) Å, α = 102.758 (3), β = 110.657 (3), γ = 101.020 (3)°, R(obs) = 0.0243 (Pz21), and a = 8.1372 (2), b = 10.6969 (2), c = 5.7840 (1) Å, α = 102.787 (2), β = 110.606 (2), γ = 100.983 (2)°, R(obs) = 0.0321 (Pz24). The structure can also be described in the non-standard pseudo-monoclinic octuple (Z = 32), F-centered (Kupčík) cell with extra points in 1/4,1/4,0; 1/4,3/4,1/2; 3/4,1/4,1/2; 3/4,3/4,0, with parameters a = 21.6466 (9), b = 8.1416 (3), c = 20.3824 (9) Å, α = 90.079 (4), β = 101.985 (5), γ = 89.948 (4)° (Pz21), and a = 21.6558 (5), b = 8.1372 (2), c = 20.3859 (8) Å, α = 90.028 (3), β = 101.994 (3), γ = 89.986 (2)° (Pz24). The structure is built of layers parallel to the bc plane, stacked along the a vector of the octuple cell, composed of ribbons parallel to the b vector: (i) ribbon of two strips of SbO5 flattened quadrangular pyramids, sharing apical edges; (ii) ribbon of edge-sharing corrugated lozenges SbO3S. Basal S atoms of pyramids share corners of lozenges. Sb atoms are displaced out of coordination polyhedra into the inter-layer space. The OD layer comprises adjacent halves of the structure building layers. The layer group is A(1)2/m1, the protocell is defined by b, c, (a/4)sin β. The MDO1 (4A) polytype is generated by repetition of the t(1,1/4,0) [or alternatively t(1,-1/4,0)] translation. The co-existence of two kinds of domains give rise to the twinning. The twin operation is 2[010], twin index 2. The total continuation of [. a2 .] generates the MDO2 (2M) polytype, space group A12/a1. Simulated and real diffraction patterns are presented. The important values (edges, angles) and

  16. Synthesis, crystal structures and properties of lead phosphite compounds

    SciTech Connect

    Song, Jun-Ling Hu, Chun-Li; Xu, Xiang; Kong, Fang; Mao, Jiang-Gao

    2015-11-15

    Here, we report the preparation and characterization of two lead(II) phosphites, namely, Pb{sub 2}(HPO{sub 3}){sub 2} and Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} through hydrothermal reaction or simple solution synthesis, respectively. A new lead phosphite, namely, Pb{sub 2}(HPO{sub 3}){sub 2}, crystallizes in the noncentrosymmetric space group Cmc2{sub 1} (no. 36), which features 3D framework formed by the interconnection of 2D layer of lead(II) phosphites and 1D chain of [Pb(HPO{sub 3}){sub 5}]{sub ∞}. The nonlinear optical properties of Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} have been studied for the first time. The synergistic effect of the stereo-active lone-pairs on Pb{sup 2+} cations and π-conjugated NO{sub 3} units in Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} produces a moderate second harmonic generation (SHG) response of ∼1.8×KDP (KH{sub 2}PO{sub 4}), which is phase matchable (type I). IR, UV–vis spectra and thermogravimetric analysis (TGA) for the two compounds were also measured. - Graphical abstract: Two lead phosphites Pb{sub 2}(HPO{sub 3}){sub 2} and Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} are studied. A new lead phosphite Pb{sub 2}(HPO{sub 3}){sub 2} features a unique 3D framework structure and Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} shows a moderate SHG response of ∼1.8×KDP (KH{sub 2}PO{sub 4}). - Highlights: • A new lead phosphite, Pb{sub 2}(HPO{sub 3}){sub 2} is reported. • Pb{sub 2}(HPO{sub 3}){sub 2} features a unique 3D framework structure. • NLO property of Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} is investigated. • Pb{sub 2}(HPO{sub 3})(NO{sub 3}){sub 2} produces a moderate SHG response of ∼1.8×KDP (KH{sub 2}PO{sub 4}).

  17. Revised age and structural interpretations of Nuka Formation at Nuka Ridge, northwestern Alaska

    USGS Publications Warehouse

    Tailleur, I.L.; Mamet, B.L.; Dutro, J.T.

    1973-01-01

    New collections of foraminifers and macrofossils from Nuka Ridge, the type area of the enigmatic Nuka Formation, demonstrate that the type Nuka Formation is not a continuous stratigraphic sequence as originally described. Paleontologic evidence indicates the presence of a structurally repeated sequence at Nuka Ridge consisting of Upper Mississippian (Meramec and younger) strata overlain by Permian beds which, in turn, are succeeded by Triassic(?) and Cretaceous rocks. Mississippian calcareous mudstone and limestone units are correlated with the Lisburne Group; microcline-bearing arkose units with Mississippian and Permian macrofossils and microfossils represent the Nuka Formation; units of chert are inferred to be of Permian and Triassic age; and wacke at the top of the sequence resembles unnamed wacke assigned to the Cretaceous elsewhere. These new data and their interpretations indicate that the type section of the Nuka Formation is inadequate. The standard for the Nuka Formation is therefore referred to a newly measured section of the middle arkosic unit of the old section.

  18. Relativistic astrophysics. Volume 2 - The structure and evolution of the universe /Revised and enlarged edition/

    NASA Astrophysics Data System (ADS)

    Zeldovich, Ia. B.; Novikov, I. D.

    This book constitutes the second volume of the monograph, Relativistic Astrophysics. It is devoted to cosmology and can be read independently of the first volume. The expansion and geometrical structure of the homogeneous, isotropic universe are examined, taking into account the local properties of the cosmological model, the relativistic theory of the universe, the propagation of photons and neutrinos, observational methods for testing cosmological theories, and the cosmological constant. Other subjects discussed are related to the physical processes in the hot universe, anisotropic cosmology, and the singularity and new theoretical developments. Attention is given to the thermodynamic equilibrium at the beginning of the cosmological expansion, the kinetics of elementary-particle processes, the radiation-dominated plasma and the relic radiation, the gravitational instability in Newtonian theory, instability in the hot model, gravitational instability in the general theory of relativity, statistical theory, and theories of galaxy formation.

  19. BBA Review Revised Mechanism and Structure of the Bacterial Type IV Secretion Systems

    PubMed Central

    Christie, Peter J.; Whitaker, Neal; González-Rivera, Christian

    2014-01-01

    The bacterial type IV secretion systems (T4SSs) translocate DNA and protein substrates to bacterial or eukaryotic target cells generally by a mechanism dependent on direct cell-to-cell contact. The T4SSs encompass two large subfamilies, the conjugation systems and the effector translocators. The conjugation systems mediate interbacterial DNA transfer and are responsible for the rapid dissemination of antibiotic resistance genes and virulence determinants in clinical settings. The effector translocators are used by many Gram-negative bacterial pathogens for delivery of potentially hundreds of virulence proteins to eukaryotic cells for modulation of different physiological processes during infection. Recently, there has been considerable progress in defining the structures of T4SS machine subunits and large machine subassemblies. Additionally, the nature of substrate translocation sequences and the contributions of accessory proteins to substrate docking with the translocation channel have been elucidated. A DNA translocation route through the Agrobacterium tumefaciens VirB/VirD4 system was defined, and both intracellular (DNA ligand, ATP energy) and extracellular (phage binding) signals were shown to activate type IV-dependent translocation. Finally, phylogenetic studies have shed light on the evolution and distribution of T4SSs, and complementary structure-function studies of diverse systems have identified adaptations tailored for novel functions in pathogenic settings. This review summarizes the recent progress in our understanding of the architecture and mechanism of action of these fascinating machines, with emphasis on the ‘archetypal’ A. tumefaciens VirB/VirD4 T4SS and related conjugation systems. PMID:24389247

  20. The NEO Personality Inventory-Revised: factor structure and gender invariance from exploratory structural equation modeling analyses in a high-stakes setting.

    PubMed

    Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z; Chamorro-Premuzic, Tomas

    2013-02-01

    This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM) technique, the authors show that model fits improve markedly over conventional confirmatory factor analyses (CFA) of the same data set, but that (a) factor interpretations do not change under ESEM analyses, (b) ESEM factor scores, just like CFA factors scores, correlate at near unity with sums of observed scores, (c) NEO-PI-R facets under ESEM analyses are invariant across gender, and (d) ESEM highlights the inappropriateness of alpha and beta as a higher order representation of NEO-PI-R facets, whereas a CFA approach might lead researchers to believe in the appropriateness of these higher order factors. These results, coupled with the existing validity evidence for the NEO-PI-R, suggest that the five-factor structure is the most parsimonious structure for summarizing NEO-PI-R responses from high-stakes settings in the United Kingdom.

  1. The Factor Structure and Psychometric Properties of the Persian Version of the Revised Prenatal Coping Inventory (Nu-PCI).

    PubMed

    Faramarzi, Mahbobeh; Pasha, Hajar; Khafri, Sorayya; Heidary, Shima

    2017-03-01

    Familiarity with coping strategies is essential for stress management during pregnancy. The Revised Prenatal Coping Inventory (Nu-PCI) was developed to assess coping strategies during pregnancy. This study aimed to assess the factor structure and psychometric properties of the Persian version of the Nu-PCI. After forward-backward translation, the Nu-PCI was administered to 210 pregnant women who were enrolled in two teaching referral clinics in the North of the Islamic Republic of Iran (Babol). The participants completed the Persian Nu-PCI and Ways of Coping Questionnaire (WCQ), which was used to determine the validity of the Persian Nu-PCI. To test construct validity of the Persian Nu-PCI, a principal components factor analysis was performed. Principal components analysis with varimax rotation showed a best fitting 3-factor structure similar to the original with three coping subscales: planning-preparation, avoidance, and spiritual-positive coping. The Persian Nu-PCI was internally consistent and within the acceptable range (α=0.89-0.97). The alpha coefficients for the Nu-PCI and the subscales of planning-preparation, avoidance, and spiritual-positive coping were high. Test-retest coefficients for the Nu-PCI and subscales were 0.98-0.99. The Nu-PCI and its subscales correlated with the WCQ in the entire sample and within each trimester. The Persian version of the Nu-PCI and the subscales of planning-preparation, avoidance, and spiritual-positive coping represent the first reliable standardized tool for measuring coping strategies during pregnancy in the Islamic Republic of Iran. Therefore, it can be applied as a quick and accurate preliminary screening tool for evaluating coping strategies throughout pregnancy in clinics and other medical and research settings.

  2. Revised structure for the phenazine antibiotic from Pseudomonas fluorescens 2-79 (NRRL B-15132).

    PubMed Central

    Brisbane, P G; Janik, L J; Tate, M E; Warren, R F

    1987-01-01

    A phenazine antibiotic (mp, 243 to 244 degrees C), isolated in a yield of 134 micrograms/ml from cultures of Pseudomonas fluorescens 2-79 (NRRL B-15132), was indistinguishable in all of its measured physicochemical (melting point, UV and infrared spectra, and gas chromatography-mass spectrometry data) and biological properties from synthetic phenazine-1-carboxylic acid. Gurusiddaiah et al. (S. Gurusiddaiah, D. M. Weller, A. Sarkar, and R. J. Cook, Antimicrob. Agents Chemother. 29:488-495, 1986) attributed a dimeric phenazine structure to an antibiotic with demonstrably similar properties obtained from the same bacterial strain. Direct comparison of the physicochemical properties of the authentic antibiotic obtained from D. M. Weller with synthetic phenazine-1-carboxylic acid and with the natural product from the present study established that all three samples were indistinguishable within the experimental error of each method. No evidence to support the existence of a biologically active dimeric species was obtained. Phenazine-1-carboxylic acid has a pKa of 4.24 +/- 0.01 (25 degrees C; I = 0.09), and its carboxylate anion shows no detectable antimicrobial activity compared with the active uncharged carboxylic acid species. These data suggest that phenazine-1-carboxylic acid is probably not an effective biological control agent for phytopathogens in environments with a pH greater than 7. Images PMID:3125789

  3. Lakshminine, a new rare oxoisoaporphine alkaloid from Sciadotenia toxifera, and structural revisions of telazoline and teladiazoline, two related oxoaporphines from Telitoxicum peruvianum and T. glaziovii.

    PubMed

    Killmer, Lew; Vogt, Frederick G; Freyer, Alan J; Menachery, Mary D; Adelman, Clark M

    2003-01-01

    Lakshminine (1), a novel oxoisoaporphine alkaloid possessing a C-6 amine substituent, was isolated from a basic fraction from the woody vines (collected from two bush-ropes) of Sciadotenia toxifera. This compound represents the first documented occurrence of an oxoisoaporphine from any Menispermaceae species other than Menispermum dauricum. The structures of two related aporphine alkaloids, telazoline (3) and teladiazoline (5), were revised on the basis of a comparison of their spectral data with that of lakshminine (1).

  4. A Revised Parallel-Sequence Galaxy Classification: Structure and Formation of S0 and Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Kormendy, John; Bender, R.

    2012-01-01

    We update van den Bergh's (1976, ApJ, 206, 883) parallel sequence galaxy classification in which S0 galaxies form a sequence S0a-S0b-S0c that parallels the sequence Sa-Sb-Sc of spiral galaxies. The ratio B/T of bulge to total light defines the position of a galaxy in this tuning fork diagram. Our classification makes one main improvement. We extend the S0a-S0b-S0c sequence to spheroidal (Sph) galaxies that are positioned in parallel to irregular galaxies in a similarly extended Sa-Sb-Sc-Im sequence. This provides a natural home for spheroidals, which previously were thought to be low-surface-brightness ellipticals. To motivate our juxtaposition of spheroidals and irregulars, we present photometry and bulge-disk decompositions of late-type S0s that bridge the gap between the more common S0b and Sph galaxies. We find several S0s in the Virgo cluster that have B/T <= 0.1. They are the S0cs that were missing from van den Bergh's paper. We update the structural parameter correlations of Sph, spiral and irregular, and elliptical galaxies. We show that spheroidals of increasing luminosity form a continuous sequence with the disks (but not bulges) of S0c-S0b-S0a galaxies. Remarkably, this Sph-S0-disk sequence is almost identical to that of irregular and spiral galaxies. We suggest that spheroidal galaxies are transformed, "red and dead" Scd-Im galaxies in the same way that many S0 galaxies are transformed, red and dead Sa-Sc spiral galaxies. Plausible transformation processes include ram-pressure gas stripping, gravitational harassment, and starvation by cutting off the late infall of cold gas. We suggest that many different processes act together to engineer S0 and Sph galaxies. This work was supported by NSF grant AST-0607490.

  5. Crystal structure of Spot 14, a modulator of fatty acid synthesis

    SciTech Connect

    Colbert, Christopher L.; Kim, Chai-Wan; Moon, Young-Ah; Henry, Lisa; Palnitkar, Maya; McKean, William B.; Fitzgerald, Kevin; Deisenhofer, Johann; Horton, Jay D.; Kwon, Hyock Joo

    2011-09-06

    Spot 14 (S14) is a protein that is abundantly expressed in lipogenic tissues and is regulated in a manner similar to other enzymes involved in fatty acid synthesis. Deletion of S14 in mice decreased lipid synthesis in lactating mammary tissue, but the mechanism of S14's action is unknown. Here we present the crystal structure of S14 to 2.65 {angstrom} and biochemical data showing that S14 can form heterodimers with MIG12. MIG12 modulates fatty acid synthesis by inducing the polymerization and activity of acetyl-CoA carboxylase, the first committed enzymatic reaction in the fatty acid synthesis pathway. Coexpression of S14 and MIG12 leads to heterodimers and reduced acetyl-CoA carboxylase polymerization and activity. The structure of S14 suggests a mechanism whereby heterodimer formation with MIG12 attenuates the ability of MIG12 to activate ACC.

  6. Optimal Full Information Synthesis for Flexible Structures Implemented on Cray Supercomputers

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Balas, Gary J.

    1995-01-01

    This paper considers an algorithm for synthesis of optimal controllers for full information feedback. The synthesis procedure reduces to a single linear matrix inequality which may be solved via established convex optimization algorithms. The computational cost of the optimization is investigated. It is demonstrated the problem dimension and corresponding matrices can become large for practical engineering problems. This algorithm represents a process that is impractical for standard workstations for large order systems. A flexible structure is presented as a design example. Control synthesis requires several days on a workstation but may be solved in a reasonable amount of time using a Cray supercomputer.

  7. Knowledge Based Synthesis of Efficient Structures for Concurrent Computation Using Fat-Trees and Pipelining.

    DTIC Science & Technology

    1986-12-31

    based on the proof is feasible. KES.U.86.11 AFO -Th, 87-0 791 Kestrel Institute Knowledge Based Synthesis of Efficient Structures for Concurrent...manner similar to an assembly line. The proof is a constructive one; a synthesis method based on the proof is feasible. 2 Chapter 2 Introduction This...These techniques are based on the use of closures as a device to schedule commu- nication, resulting from divide and conquer, between halves of a tree

  8. Motualevic Acids and Analogs: Synthesis and Antimicrobial Structure Activity Relationships

    PubMed Central

    Cheruku, Pradeep; Keffer, Jessica L.; Dogo-Isonagie, Cajetan; Bewley, Carole A.

    2010-01-01

    Synthesis of the marine natural products motualevic acids A, E, and analogs in which modifications have been made to the ω-brominated lipid (E)-14,14-dibromotetra-deca-2,13-dienoic acid or amino acid unit are reported, together with antimicrobial activities against Staphylococcus aureus, methicillin-resistant S. aureus, Enterococcus faecium, and vancomycin-resistant Enterococcus. PMID:20538459

  9. Gendered Performances during Peer Revision

    ERIC Educational Resources Information Center

    Styslinger, Mary E.

    2008-01-01

    This study explored the ways gender is accomplished in varied social contexts during the peer revision process in a secondary English classroom. Using a post-structural feminist theoretical framework, an analysis of classroom discourse provided a basis for understanding the performance of gender during peer revision, the effects of gender…

  10. Interior Design: Revision as Focus.

    ERIC Educational Resources Information Center

    Smede, Shelly D.

    2000-01-01

    Describes how the author teaches her eighth-grade students to revise their writing, providing "working revision days" in class, offering direction and structure, and thereby helping students learn how much impact going back to a piece of writing and making sweeping changes can have on the end result. (SR)

  11. A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E

    PubMed Central

    Reimann, Marcel; Sandjo, Louis P; Antelo, Luis; Thines, Eckhard; Siepe, Isabella

    2017-01-01

    Two hitherto unknown fusaricidins were obtained from fermentation broths of three Paenibacillus strains. After structure elucidation based on tandem mass spectrometry and NMR spectroscopy, fusaricidin E was synthesized to confirm the structure and the suggested stereochemistry. The synthesis was based on a new strategy which includes an efficient access to the 15-guanidino-3-hydroxypentadecanoyl (GHPD) side chain from erucamide. PMID:28781709

  12. A new member of the fusaricidin family - structure elucidation and synthesis of fusaricidin E.

    PubMed

    Reimann, Marcel; Sandjo, Louis P; Antelo, Luis; Thines, Eckhard; Siepe, Isabella; Opatz, Till

    2017-01-01

    Two hitherto unknown fusaricidins were obtained from fermentation broths of three Paenibacillus strains. After structure elucidation based on tandem mass spectrometry and NMR spectroscopy, fusaricidin E was synthesized to confirm the structure and the suggested stereochemistry. The synthesis was based on a new strategy which includes an efficient access to the 15-guanidino-3-hydroxypentadecanoyl (GHPD) side chain from erucamide.

  13. ACCESS-2: Approximation Concepts Code for Efficient Structural Synthesis, user's guide

    NASA Technical Reports Server (NTRS)

    Miura, H.; Schmit, L. A., Jr.

    1978-01-01

    A user's guide is presented for the ACCESS-2 computer program. ACCESS-2 is a research oriented program which implements a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and general mathematical programming algorithms are applied in the design optimization procedure.

  14. Structure sensitivity of Cu and CuZn catalysts relevant to industrial methanol synthesis

    PubMed Central

    van den Berg, Roy; Prieto, Gonzalo; Korpershoek, Gerda; van der Wal, Lars I.; van Bunningen, Arnoldus J.; Lægsgaard-Jørgensen, Susanne; de Jongh, Petra E.; de Jong, Krijn P.

    2016-01-01

    For decades it has been debated whether the conversion of synthesis gas to methanol over copper catalysts is sensitive or insensitive to the structure of the copper surface. Here we have systematically investigated the effect of the copper particle size in the range where changes in surface structure occur, that is, below 10 nm, for catalysts with and without zinc promotor at industrially relevant conditions for methanol synthesis. Regardless of the presence or absence of a zinc promotor in the form of zinc oxide or zinc silicate, the surface-specific activity decreases significantly for copper particles smaller than 8 nm, thus revealing structure sensitivity. In view of recent theoretical studies we propose that the methanol synthesis reaction takes place at copper surface sites with a unique configuration of atoms such as step-edge sites, which smaller particles cannot accommodate. PMID:27703166

  15. Laser-assisted solid-state synthesis of carbon nanotube/silicon core/shell structures.

    PubMed

    Mahjouri-Samani, M; Zhou, Y S; Fan, L; Gao, Y; Xiong, W; More, K L; Jiang, L; Lu, Y F

    2013-06-28

    A single-step solid-state synthetic approach was developed for the synthesis of silicon-coated carbon nanotube (CNT) core/shell structures. This was achieved through laser-induced melting and evaporation of CNT-deposited Si substrates using a continuous wavelength CO2 laser. The synthesis location of the CNT/Si structures was defined by the laser-irradiated spots. The thickness of the coating was controlled by tuning the laser power and synthesis time during the coating process. This laser-based synthetic technique provides a convenient approach for solid-state, controllable, gas-free, simple and cost-effective fabrication of CNT/Si core/shell structures.

  16. Revision Rhinoplasty.

    PubMed

    Loyo, Myriam; Wang, Tom D

    2016-01-01

    Revision rhinoplasty is one of the most challenging operations the facial plastic surgeon performs given the complex 3-dimensional anatomy of the nose and the psychological impact it has on patients. The intricate interplay of cartilages, bone, and soft tissue in the nose gives it its aesthetic and function. Facial harmony and attractiveness depends greatly on the nose given its central position in the face. In the following article, the authors review common motivations and anatomic findings for patients seeking revision rhinoplasty based on the senior author's 30-year experience with rhinoplasty and a review of the literature.

  17. General sacrificial template method for the synthesis of cadmium chalcogenide hollow structures.

    PubMed

    Miao, Jian-Jun; Jiang, Li-Ping; Liu, Chang; Zhu, Jian-Min; Zhu, Jun-Jie

    2007-07-09

    Semiconductor CdX (X=Te, Se, S) hollow structures have been successfully prepared by using Cd(OH)Cl precursors as a sacrificial template. The hollow structures can be hollow spheres or tubes by controlling the shape of the sacrificial template. The products were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and energy-dispersive spectrometry. The obtained results showed that the hollow structures had complementary shapes and sizes of the original sacrificial templates. This is a general method for the synthesis of cadmium chalcogenide hollow structures, and the method is simpler and more practical than direct synthesis of certain hollow structures, which further widens the avenue to using those materials that have been synthesized with various shapes to fabricate specific hollow structures.

  18. Acetabular Cup Revision.

    PubMed

    Kim, Young-Ho

    2017-09-01

    The use of acetabular cup revision arthroplasty is on the rise as demands for total hip arthroplasty, improved life expectancies, and the need for individual activity increase. For an acetabular cup revision to be successful, the cup should gain stable fixation within the remaining supportive bone of the acetabulum. Since the patient's remaining supportive acetabular bone stock plays an important role in the success of revision, accurate classification of the degree of acetabular bone defect is necessary. The Paprosky classification system is most commonly used when determining the location and degree of acetabular bone loss. Common treatment options include: acetabular liner exchange, high hip center, oblong cup, trabecular metal cup with augment, bipolar cup, bulk structural graft, cemented cup, uncemented cup including jumbo cup, acetabular reinforcement device (cage), trabecular metal cup cage. The optimal treatment option is dependent upon the degree of the discontinuity, the amount of available bone stock and the likelihood of achieving stable fixation upon supportive host bone. To achieve successful acetabular cup revision, accurate evaluation of bone defect preoperatively and intraoperatively, proper choice of method of acetabular revision according to the evaluation of acetabular bone deficiency, proper technique to get primary stability of implant such as precise grafting technique, and stable fixation of implant are mandatory.

  19. The Factorial Structure and Construct Validity of the Psychopathy Checklist-Revised (PCL-R) among Alcoholic Inpatients.

    ERIC Educational Resources Information Center

    Windle, Michael; Dumenci, Levent

    1999-01-01

    Conducted simultaneous group confirmatory factor analyses of the Psychopathy Checklist-Revised (PCL-R)(R. Hare, 1991) with 740 alcoholic inpatients. Results provide general support for the use of the PCL-R with alcoholic inpatients, although there was substantial intercorrelation for the factors of Personality and Behavioral Features. (SLD)

  20. ACCESS 1: Approximation Concepts Code for Efficient Structural Synthesis program documentation and user's guide

    NASA Technical Reports Server (NTRS)

    Miura, H.; Schmit, L. A., Jr.

    1976-01-01

    The program documentation and user's guide for the ACCESS-1 computer program is presented. ACCESS-1 is a research oriented program which implements a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and general mathematical programming algorithms are applied in the design optimization procedure. Implementation of the computer program, preparation of input data and basic program structure are described, and three illustrative examples are given.

  1. Revised stereochemistry of ceramide-trafficking inhibitor HPA-12 by X-ray crystallography analysis.

    PubMed

    Ueno, Masaharu; Huang, Yi-Yong; Yamano, Akihito; Kobayashi, Shū

    2013-06-07

    In response to Berkeš's report revising the stereochemistry of HPA-12, an important ceramide-trafficking inhibitor that was discovered and synthesized and its stereochemistry determined in 2001, the synthesis and the stereochemistry were reinvestigated. A large-scale synthetic method for HPA-12 based on a Zn-catalyzed asymmetric Mannich-type reaction in water was developed. Single crystals of HPA-12 for X-ray crystallographic analysis were obtained from ethyl propionate/n-hexane, and the stereochemistry was definitely determined to be 1R,3S, consistent with Berkeš's revised structure.

  2. Parent and trisubstituted triazacoronenes: synthesis, crystal structure and physicochemical properties.

    PubMed

    Tan, Qitao; Chen, Huanhuan; Xia, Huaida; Liu, Bingxin; Xu, Bin

    2016-01-11

    A four-step synthesis of the C3-symmetric parent 1,5,9-triazacoronene (TAC) and its derivatives was achieved using a three-fold Bischler-Napieralski cyclization as the key step. The single-crystal X-ray diffraction of 1b (R = n-Bu) demonstrates that the azacoronene core is perfectly co-planar and the molecules adopt a favorable 2-D "brick-wall" arrangement with strong π-π interactions. The unique stacking, tunable photophysical and electronic properties, and high thermal stability should make them promising candidates for emissive and electron-transport materials.

  3. Tris(acetonitrile)chloropalladium tetrafluoroborate synthesis, application and structural analysis

    NASA Astrophysics Data System (ADS)

    Dybała, Izabela; Demchuk, Oleg M.

    2016-10-01

    Results of the single crystal X-ray diffraction analysis of tris(acetonitrile)chloropalladium tetrafluoroborate [PdCl(CH3CN)3]BF4 are presented in details. It was found that the title compound crystallises in the monoclinic system, in the space group C2/c. The role of charge-assisted C-HṡṡṡF-B interactions in crystal architecture was investigated. Due to its untypical properties the prepared [PdCl(CH3CN)3]BF4 has proved to be an excellent palladium source in the synthesis of phosphine-palladium complexes.

  4. Synthesis, Structure, and Properties of PBO/SWNT Composites

    DTIC Science & Technology

    2002-01-01

    strength of the commercial PBO fiber ( Zylon HM) is 5.8 GPa.19 If similar tensile strength improvement with the incorporation of SWNTs is achieved in Zylon ...the fiber axis, a low percolation threshold should be ob- served. Raman spectra of the HiPco SWNT, PBO ( Zylon HM), and PBO/SWNT (90/10) fibers are...the com- mercial PBO fiber ( Zylon HM) Raman spectra was used for comparison. Conclusions SWNTs were well-dispersed during PBO synthesis in PPA. PBO

  5. Assessment of telavancin minimal inhibitory concentrations by revised broth microdilution method in phase 3 complicated skin and skin-structure infection clinical trial isolates.

    PubMed

    Smart, Jennifer I; Corey, G Ralph; Stryjewski, Martin E; Wang, Whedy; Barriere, Steven L

    2017-03-01

    The broth microdilution (BMD) MIC testing method for telavancin was recently revised BMD (rBMD) to improve accuracy and reproducibility. Staphylococcus aureus isolates from telavancin phase 3 complicated skin and skin-structure infection (cSSSI) studies were tested using the rBMD method. Retesting of 1132 isolates produced MICs ranging from ≤0.015 to 0.12μg/mL that were 8-fold lower than the original method. All isolates tested remained susceptible to telavancin at the revised susceptibility breakpoint of 0.12μg/mL. The clinical cure and microbiological eradication rates were 90% (368/409) and 89% (366/409) for telavancin-treated patients, and were similar for patients with methicillin-susceptible and -resistant S. aureus isolates and S. aureus isolates with elevated vancomycin MICs (≥1μg/mL). The data presented here are aimed to update the literature and better inform clinicians and clinical microbiologists about the revised telavancin MICs, as well as the corresponding clinical and microbiological cure rates for cSSSI patients.

  6. Structural tailoring and feedback control synthesis - An interdisciplinary approach

    NASA Technical Reports Server (NTRS)

    Belvin, W. Keith; Park, K. C.

    1988-01-01

    Structural tailoring provides an attractive method to optimize the performance of actively controlled space structures. However, the simultaneous optimization of control gains and structural properties often becomes prohibitively expensive for large systems and physical insight is often lost in the resulting control law. This paper presents a method for optimization of the closed loop structural system using only structural tailoring. Optimal Linear Quadratic Regulator (LQR) control theory is used with weighting matrices chosen based on physical considerations. The LQR control law depends only on two scalar gains and the structural properties. Hence, the closed loop-performance can be expressed in terms of the structural parameters. Results are given for a beam and a truss-beam to show the simplicity of the method and the importance of structural tailoring to increase dynamic performance and to reduce the control effort.

  7. Controlled Synthesis of Ultralong Carbon Nanotubes with Perfect Structures and Extraordinary Properties.

    PubMed

    Zhang, Rufan; Zhang, Yingying; Wei, Fei

    2017-02-21

    Carbon nanotubes (CNTs) have drawn intensive research interest in the past 25 years due to their excellent properties and wide applications. Ultralong CNTs refers to the horizontally aligned CNT arrays which are usually grown on flat substrates, parallel with each other with large intertube distances. They usually have perfect structures, excellent properties, and lengths up to centimeters, even decimeters. Ultralong CNTs are promising candidates as building blocks for transparent displays, nanoelectronics, superstrong tethers, aeronautics and aerospace materials, etc. The controlled synthesis of ultralong CNTs with perfect structures is the key to fully exploit the extraordinary properties of CNTs. CNTs are typical one-dimensional single-crystal nanomaterials. It has always been a great challenge how to grow macroscale single-crystals with no defects. Thus, the synthesis of ultralong CNTs with no defect is of significant importance from both fundamental and industrial aspects. In this Account, we focus on our progress on the controlled synthesis of ultralong CNTs with perfect structures and excellent properties. A deep understanding of the CNT growth mechanism is the first step for the controlled synthesis of ultralong CNTs with high quality. We first introduce the growth mechanism for ultralong CNTs and the main factor affecting their structures. We then discuss the strategies to control the defects in the as-grown ultralong CNTs. With these approaches, ultralong high-quality CNTs with different structures can be obtained. By completely eliminating the factors which may induce defects in the CNT walls, ultralong CNTs with perfect structures can be obtained. Their chiral indices keep unchanged for several centimeters long along the axial direction of the CNTs. The defect-free structures render the ultralong CNTs with excellent electrical, mechanical and thermal properties. The as-grown ultralong CNTs exhibit superhigh mechanical strength (>100 GPa) and their

  8. The Factorial Structure of the Arabic Version of the Revised Collett--Lester Fear of Death Scale

    ERIC Educational Resources Information Center

    Abdel-Khalek, Ahmed; Lester, David

    2004-01-01

    A sample of 209 volunteer Kuwaiti undergraduates responded to an Arabic version of the Revised Collett-Lester Fear of Death Scale with 4 subscales: Death of Self, Dying of Self, Death of Others, and Dying of Others. Reliabilities of the 4 subscales and of the grand total score ranged from 0.75 to 0.92, which is considered adequate. A 4-factor…

  9. Total chemical synthesis and X-ray structure of kaliotoxin by racemic protein crystallography

    SciTech Connect

    Pentelute, Brad L.; Mandal, Kalyaneswar; Gates, Zachary P.; Sawaya, Michael R.; Yeates, Todd O.; Kent, Stephen B.H.

    2010-11-05

    Here we report the total synthesis of kaliotoxin by 'one pot' native chemical ligation of three synthetic peptides. A racemic mixture of D- and L-kaliotoxin synthetic protein molecules gave crystals in the centrosymmetric space groupP that diffracted to atomic-resolution (0.95 {angstrom}), enabling the X-ray structure of kaliotoxin to be determined by direct methods.

  10. Computer simulation of low-temperature ceramics with a hierarchical structure synthesis

    NASA Astrophysics Data System (ADS)

    Leitsin, Vladimir; Ponomarev, Sergey; Dmitrieva, Maria

    2015-10-01

    Low-temperature ceramics has been widely used in modern materials production, especially radio engineering and medical supplies. Creation of a comprehensive computer model of the processes of low-temperature ceramics synthesis allows to investigate the kinetics of sintering processes and get the forecast of structural and geometric characteristics.

  11. Rapid and Convenient Synthesis of the 1,4-Dihydropyridine Privileged Structure

    ERIC Educational Resources Information Center

    Cheung, Lawrence L. W.; Styler, Sarah A.; Dicks, Andrew P.

    2010-01-01

    A short, semi-microscale synthesis of two 1,4-dihydropyridine drug analogues via a Hantzsch reaction is described, which is appropriate for a second-year undergraduate organic laboratory. Products are specifically chosen to highlight the biological relevance of this compound type while introducing the notion of a privileged structure.…

  12. Robust nonlinear dynamic inversion flight control design using structured singular value synthesis based on genetic algorithm

    NASA Astrophysics Data System (ADS)

    Ying, Sibin; Ai, Jianliang; Luo, Changhang; Wang, Peng

    2006-11-01

    Non-linear Dynamic Inversion (NDI) is a technique for control law design, which is based on the feedback linearization and achieving desired dynamic response characteristics. NDI requires an ideal and precise model, however, there must be some errors due to the modeling error or actuator faults, therefore the control law designed by NDI has less robustness. Combining with structured singular value μ synthesis method, the system's robustness can be improved notably. The designed controller, which uses the structured singular value μ synthesis method, has high dimensions, and the dimensions must be reduced when we calculate it. This paper presents a new method for the design of robust flight control, which uses structured singular value μ synthesis based on genetic algorithm. The designed controller, which uses this method, can reduce the dimensions obviously compared with the normal method of structured singular value synthesis, so it is easier for application. The presented method is applied to robustness controller design of some super maneuverable fighter. The simulation results show that the dynamic inversion control law achieves a high level of performance in post-stall maneuver condition, and the whole control system has perfect robustness and anti-disturbance ability.

  13. Oligomeric flavanoids. Part 26. Structure and synthesis of the first profisetinidins with epifisetinidol constituent units

    Treesearch

    Petrus J. Steynberg; Jan P. Steynberg; E. Vincent Brandt; Daneel Ferreira; Richard W. Hemingway

    1997-01-01

    The natural occurrence of the first oligomeric profisetinidins with (2R,3R}-2,3-cis-epifisetinidol chain extender units is demonstrated in the bark of Pithecellobium dulce (Guamuchil). Semi-synthesis using the appropriate flavan-3-ol and flavan-3,4-diol precursors permits unequivocal structural...

  14. Rapid and Convenient Synthesis of the 1,4-Dihydropyridine Privileged Structure

    ERIC Educational Resources Information Center

    Cheung, Lawrence L. W.; Styler, Sarah A.; Dicks, Andrew P.

    2010-01-01

    A short, semi-microscale synthesis of two 1,4-dihydropyridine drug analogues via a Hantzsch reaction is described, which is appropriate for a second-year undergraduate organic laboratory. Products are specifically chosen to highlight the biological relevance of this compound type while introducing the notion of a privileged structure.…

  15. Design, synthesis, and structure-activity relationship studies of new phenolic DNA gyrase inhibitors.

    PubMed

    Lübbers, Thomas; Angehrn, Peter; Gmünder, Hans; Herzig, Silvia

    2007-08-15

    Starting from a biased needle screening hit 3a, we report herein the design and synthesis of a series of novel 2,3-dihydroisoindol-1-ones structurally related to cyclothialidine 2 with DNA gyrase inhibitory activity. In this series, some compounds exhibited promising antibacterial activity against gram-positive bacterial strains.

  16. Melanostatin, a new melanin synthesis inhibitor. Production, isolation, chemical properties, structure and biological activity.

    PubMed

    Ishihara, Y; Oka, M; Tsunakawa, M; Tomita, K; Hatori, M; Yamamoto, H; Kamei, H; Miyaki, T; Konishi, M; Oki, T

    1991-01-01

    Melanostatin, a new antibiotic with melanin synthesis inhibitor activity, was isolated from the fermentation broth of Streptomyces clavifer No. N924-2. Its structure was determined by spectral analysis and degradation experiments. Melanostatin strongly inhibited melanin formation in Streptomyces bikiniensis NRRL B-1049 and B16 melanoma cells.

  17. Total Synthesis and Structure-Activity Relationship of Glycoglycerolipids from Marine Organisms

    PubMed Central

    Zhang, Jun; Li, Chunxia; Yu, Guangli; Guan, Huashi

    2014-01-01

    Glycoglycerolipids occur widely in natural products, especially in the marine species. Glycoglycerolipids have been shown to possess a variety of bioactivities. This paper will review the different methodologies and strategies for the synthesis of biological glycoglycerolipids and their analogs for bioactivity assay. In addition, the bioactivities and structure-activity relationship of the glycoglycerolipids are also briefly outlined. PMID:24945415

  18. First-principles prediction of stable SiC cage structures and their synthesis pathways

    NASA Astrophysics Data System (ADS)

    Pochet, Pascal; Genovese, Luigi; Caliste, Damien; Rousseau, Ian; Goedecker, Stefan; Deutsch, Thierry

    2010-07-01

    In this paper we use density functional theory calculations to investigate the structure and the stability of different SiC cagelike clusters. In addition to the fullerene family and the mixed four and six membered ring family, we introduce a family based on reconstructed nanotube slices. We propose an alternative synthesis pathway starting from SiC nanotubes.

  19. Poliovirus RNA synthesis in vitro: structural elements and antibody inhibition

    SciTech Connect

    Semler, B.L.; Hanecak, R.; Dorner, L.F.; Anderson, C.W.; Wimmer, E.

    1983-01-01

    The poliovirus RNA polymerase complex has been analyzed by immunoautoradiography using antibody probes derived from purified replicase (P3) region viral polypeptides. Antibody preparations made against the polio RNA polymerase, P3-4b, detected a previously unreported cellular protein that copurifies with the RNA polymerase. An IgG fraction purified from rabbit antiserum to polypeptide P3-2, a precursor fo the RNA polymerase, specifically inhibits poliovirus RNA synthesis in vitro. The authors have also immunoprecipitated a 60,000-dalton protein (P3-4a) with antiserum to protein P3-4b and have determined the precise genomic map position of this protein by automated Edman degradation. Protein P3-4a originates by cleavage of the RNA polymerase precursor at a glutamine-glucine amino acid pair not previously reported to be a viral cleavage site.

  20. Synthesis, structure and imaging of oligodeoxyribonucleotides with tellurium-nucleobase derivatization

    SciTech Connect

    Sheng, J.; Soares, A.; Hassan, A. E. A.; Zhang, W.; Zhou, J.; Xu, B.; Huang, Z.

    2011-05-01

    We report here the first synthesis of 5-phenyl-telluride-thymidine derivatives and the Te-phosphoramidite. We also report here the synthesis, structure and STM current-imaging studies of DNA oligonucleotides containing the nucleobases (thymine) derivatized with 5-phenyl-telluride functionality (5-Te). Our results show that the 5-Te-DNA is stable, and that the Te-DNA duplex has the thermo-stability similar to the corresponding native duplex. The crystal structure indicates that the 5-Te-DNA duplex structure is virtually identical to the native one, and that the Te-modified T and native A interact similarly to the native T and A pair. Furthermore, while the corresponding native showed weak signals, the DNA duplex modified with electron-rich tellurium functionality showed strong topographic and current peaks by STM imaging, suggesting a potential strategy to directly image DNA without structural perturbation.

  1. Synthesis Structure and Imaging of Oligodeoxyribonucleotides with Tellurium-nucleobase Derivatization

    SciTech Connect

    J Sheng; A Hassan; W Zhang; J Zhou; B Xu; A Soares; Z Huang

    2011-12-31

    We report here the first synthesis of 5-phenyl-telluride-thymidine derivatives and the Te-phosphoramidite. We also report here the synthesis, structure and STM current-imaging studies of DNA oligonucleotides containing the nucleobases (thymine) derivatized with 5-phenyl-telluride functionality (5-Te). Our results show that the 5-Te-DNA is stable, and that the Te-DNA duplex has the thermo-stability similar to the corresponding native duplex. The crystal structure indicates that the 5-Te-DNA duplex structure is virtually identical to the native one, and that the Te-modified T and native A interact similarly to the native T and A pair. Furthermore, while the corresponding native showed weak signals, the DNA duplex modified with electron-rich tellurium functionality showed strong topographic and current peaks by STM imaging, suggesting a potential strategy to directly image DNA without structural perturbation.

  2. Structural characterization of rotavirus-directed synthesis and assembly of metallic nanoparticle arrays.

    PubMed

    Plascencia-Villa, Germán; Medina, Ariosto; Palomares, Laura A; Ramírez, Octavio T; Ascencio, Jorge A

    2013-08-01

    Self-assembled structures derived of viral proteins display sophisticated structures that are difficult to obtain with even advanced synthesis methods and the use of protein nanotubes for synthesis and organization of inorganic nanoarrays into well-defined architectures are here reported. Nanoparticle arrays derived of rotavirus VP6 nanotubes were synthesized by in situ functionalization with silver and gold nanoparticles. The size and morphology of metal nanoparticles were characterized by transmission electron microscopy (TEM) and high resolution TEM (HR-TEM). Processing of micrographs to obtain fast Fourier transforms (FFT) patterns of nanoparticles shown that the preferred morphologies are fcc-like and multiple twinned ones. Micrographs were used to assign structure and orientation, and the elemental composition analysis was performed with energy dispersive spectroscopy (EDS). Structural characterization of functionalized rotavirus VP6 demonstrated its utility for directed construction of hybrid anisotropic nanomaterials formed by arrays of metallic nanoparticles.

  3. Synthesis, structure and imaging of oligodeoxyribonucleotides with tellurium-nucleobase derivatization.

    PubMed

    Sheng, Jia; Hassan, Abdalla E A; Zhang, Wen; Zhou, Jianfeng; Xu, Bingqian; Soares, Alexei S; Huang, Zhen

    2011-05-01

    We report here the first synthesis of 5-phenyl-telluride-thymidine derivatives and the Te-phosphoramidite. We also report here the synthesis, structure and STM current-imaging studies of DNA oligonucleotides containing the nucleobases (thymine) derivatized with 5-phenyl-telluride functionality (5-Te). Our results show that the 5-Te-DNA is stable, and that the Te-DNA duplex has the thermo-stability similar to the corresponding native duplex. The crystal structure indicates that the 5-Te-DNA duplex structure is virtually identical to the native one, and that the Te-modified T and native A interact similarly to the native T and A pair. Furthermore, while the corresponding native showed weak signals, the DNA duplex modified with electron-rich tellurium functionality showed strong topographic and current peaks by STM imaging, suggesting a potential strategy to directly image DNA without structural perturbation.

  4. Origami-inspired active structures: a synthesis and review

    NASA Astrophysics Data System (ADS)

    Peraza-Hernandez, Edwin A.; Hartl, Darren J.; Malak, Richard J., Jr.; Lagoudas, Dimitris C.

    2014-09-01

    Origami, the ancient art of paper folding, has inspired the design of engineering devices and structures for decades. The underlying principles of origami are very general, which has led to applications ranging from cardboard containers to deployable space structures. More recently, researchers have become interested in the use of active materials (i.e., those that convert various forms of energy into mechanical work) to effect the desired folding behavior. When used in a suitable geometry, active materials allow engineers to create self-folding structures. Such structures are capable of performing folding and/or unfolding operations without being kinematically manipulated by external forces or moments. This is advantageous for many applications including space systems, underwater robotics, small scale devices, and self-assembling systems. This article is a survey and analysis of prior work on active self-folding structures as well as methods and tools available for the design of folding structures in general and self-folding structures in particular. The goal is to provide researchers and practitioners with a systematic view of the state-of-the-art in this important and evolving area. Unifying structural principles for active self-folding structures are identified and used as a basis for a quantitative and qualitative comparison of numerous classes of active materials. Design considerations specific to folded structures are examined, including the issues of crease pattern identification and fold kinematics. Although few tools have been created with active materials in mind, many of them are useful in the overall design process for active self-folding structures. Finally, the article concludes with a discussion of open questions for the field of origami-inspired engineering.

  5. On the Numerical Solution of the Integral Equation Formulation for Transient Structural Synthesis

    DTIC Science & Technology

    2014-09-01

    IRF impulse response function MDOF multiple degree-of-freedom SDOF single degree-of-freedom VIDE Volterra integro-differential equation VIE ...integral equation formulation to structural synthesis is based on the convolution integral and results in a Volterra integral equation ( VIE ) of the...strictly limited to linear models. The theory of transient structural modification, and the associated governing VIE , is based on the convolution

  6. Polyrhythmic Tapping: Examining the Effectiveness of the Strategy of Organizing Rhythmic Structures through Synthesis

    ERIC Educational Resources Information Center

    Yokus, Hamit; Yokus, Tuba

    2015-01-01

    In this study the strategy of organizing rhythmic structures through synthesis is named, and defined, and its procedures are described. Its effectiveness for teaching the execution of 3:2, 4:3, 8:3, 5:4, and 3:5 polyrhythmic structures is examined and described. Pre-test and Post-test Control Group Design was employed to test the effectiveness of…

  7. Field-structured material media and methods for synthesis thereof

    DOEpatents

    Martin, James E.; Hughes, Robert C.; Anderson, Robert A.

    2001-09-18

    The present application is directed to a new class of composite materials, called field-structured composite (FSC) materials, which comprise a oriented aggregate structure made of magnetic particles suspended in a nonmagnetic medium, and to a new class of processes for their manufacture. FSC materials have much potential for application, including use in chemical, optical, environmental, and mechanical sensors.

  8. Topography and Dynamics of Synthesis of Structural Proteins of Newcastle Disease Virus

    PubMed Central

    Zhdanov, Victor M.; Azadova, Nonna B.; Uryvayev, Leonid V.

    1966-01-01

    Zhdanov, Victor M. (The D. I. Ivanovsky Institute of Virology, Moscow, USSR), Nonna B. Azadova, and Leonid V. Uryvayev. Topography and dynamics of synthesis of structural proteins of Newcastle disease virus. J. Bacteriol. 91:1902–1906. 1966.—Newcastle disease virus S and V antigens are synthesized in the cytoplasm, as revealed by the immunofluorescence method. In some experiments, S antigen was found also in the nucleoli. Actinomycin D moderately decreased the titer of infectious virus and V antigen and accelerated the time of appearance of mature virus. Proflavine sharply decreased the synthesis of both antigens and the release of mature virus. Images PMID:5327911

  9. An Iminium Ion Cascade Annulation Strategy for the Synthesis of Akuammiline Alkaloid Pentacyclic Core Structures.

    PubMed

    Andreansky, Eric S; Blakey, Simon B

    2016-12-16

    The akuammiline alkaloids are a family of indole monoterpene natural products known for their polycyclic cage-like structures. An iminium ion cascade annulation approach was developed, simultaneously synthesizing both the C and D rings of these natural products by annulation onto a protected indole ring. This reaction allowed the synthesis of a key tetracyclic intermediate toward these natural products. This tetracycle was used for the synthesis of the pentacyclic methanoquinolizidine core present in such alkaloids as akuammiline and strictamine as well as the pentacyclic furoindoline core found in pseudoakuammigine.

  10. Synthesis, structural and morphological characterization of the perovskite LaYbO3

    NASA Astrophysics Data System (ADS)

    Cabrera Ramírez, A.; Charry Pastrana, F. E.; Roa Rojas, J.; Landinez Tellez, D. A.; Fajardo, F.

    2016-02-01

    In this work we report synthesis of the LaYbO3 ceramics material by the solid state reaction technique and its structural and morphological characterization from X-ray diffraction and Scanning Electron Microscopy experiments. Rietveld refinement of the diffraction patterns reveals that this material crystallizes in an orthorhombic perovskite, Pnma space group (#62) with lattice parameters a=6.0233Å, b=8.2080Å and c=5.7203Å. Systematic monitoring of the synthesis process is carried out through analysis of results of X-ray diffraction. The surface morphology of the samples was qualitatively analysed as a function of the sintering process.

  11. Synthesis and characterization of a new structure of gas hydrate.

    PubMed

    Yang, L; Tulk, C A; Klug, D D; Moudrakovski, I L; Ratcliffe, C I; Ripmeester, J A; Chakoumakos, B C; Ehm, L; Martin, C D; Parise, J B

    2009-04-14

    Atoms and molecules <0.9 nm in diameter can be incorporated in the cages formed by hydrogen-bonded water molecules making up the crystalline solid clathrate hydrates. For these materials crystallographic structures generally fall into 3 categories, which are 2 cubic forms and a hexagonal form. A unique clathrate hydrate structure, previously known only hypothetically, has been synthesized at high pressure and recovered at 77 K and ambient pressure in these experiments. These samples contain Xe as a guest atom and the details of this previously unobserved structure are described here, most notably the host-guest ratio is similar to the cubic Xe clathrate starting material. After pressure quench recovery to 1 atmosphere the structure shows considerable metastability with increasing temperature (T <160 K) before reverting back to the cubic form. This evidence of structural complexity in compositionally similar clathrate compounds indicates that the reaction path may be an important determinant of the structure, and impacts upon the structures that might be encountered in nature.

  12. Synthesis and characterization of a new structure of gas hydrate

    PubMed Central

    Yang, L.; Tulk, C. A.; Klug, D. D.; Moudrakovski, I. L.; Ratcliffe, C. I.; Ripmeester, J. A.; Chakoumakos, B. C.; Ehm, L.; Martin, C. D.; Parise, J. B.

    2009-01-01

    Atoms and molecules <0.9 nm in diameter can be incorporated in the cages formed by hydrogen-bonded water molecules making up the crystalline solid clathrate hydrates. For these materials crystallographic structures generally fall into 3 categories, which are 2 cubic forms and a hexagonal form. A unique clathrate hydrate structure, previously known only hypothetically, has been synthesized at high pressure and recovered at 77 K and ambient pressure in these experiments. These samples contain Xe as a guest atom and the details of this previously unobserved structure are described here, most notably the host-guest ratio is similar to the cubic Xe clathrate starting material. After pressure quench recovery to 1 atmosphere the structure shows considerable metastability with increasing temperature (T <160 K) before reverting back to the cubic form. This evidence of structural complexity in compositionally similar clathrate compounds indicates that the reaction path may be an important determinant of the structure, and impacts upon the structures that might be encountered in nature. PMID:19332791

  13. Synthesis, physicochemical, structural and rheological characterizations of carboxymethyl xanthan derivatives.

    PubMed

    Yahoum, Madiha M; Moulai-Mostefa, Nadji; Le Cerf, Didier

    2016-12-10

    The aim of this work was to synthesize a carboxymethylated xanthan (CMXG) via an etherification reaction between different ratios (2, 4, and 6) of xanthan gum (XG) and monochloroacetic acid (MCAA) using the Williamson synthesis method. The synthetized products were characterized in terms of their physico-chemical and rheological properties. Both FTIR and proton nuclear magnetic resonance (H(1) NMR) analyses confirmed the grafting of carboxymethyl groups on xanthan hydroxyl groups. The obtained results demonstrated that the degree of substitution was proportional to the chloroacetic acid and xanthan gum ratios. The obtained carboxymethyl derivatives presented greater hydrophilicity and lower molecular weights with increasing degrees of substitution than native xanthan gum. The rheological study revealed that the viscosity of the CMXG derivatives decreased with the degree of substitution and with the conservation of the shear-thinning and weak gel behaviours. The flow curves suggested the existence of two different populations of particles consisting of CMXG particles with a smaller average size and a second population formed by the residual fractions of native XG particles. It was also found that the elastic modulus of XG was largely higher than that of the CMXG derivatives and decreased with increasing DS. For the CMXG derivatives, two regions of viscoelastic behaviour were observed, which were separated by a crossover point corresponding to the critical frequency and relaxation time, i.e., the time required for stress relaxation.

  14. Synthesis of the reported structures for kealiinines B and C.

    PubMed

    Gibbons, Joseph B; Gligorich, Keith M; Welm, Bryan E; Looper, Ryan E

    2012-09-21

    Syntheses of the reported structures of kealiinines B and C have been executed. An intermolecular electrophile-induced cyclization of a pendant arene on an ene-guanidine affords the tetracyclic, oxidized naphthimidazole cores.

  15. DNA Origami Rotaxanes: Tailored Synthesis and Controlled Structure Switching.

    PubMed

    Powell, John T; Akhuetie-Oni, Benjamin O; Zhang, Zhao; Lin, Chenxiang

    2016-09-12

    Mechanically interlocked supramolecular assemblies are appealing building blocks for creating functional nanodevices. Herein, we describe the multistep assembly of large DNA origami rotaxanes that are capable of programmable structural switching. We validated the topology and structural integrity of these rotaxanes by analyzing the intermediate and final products of various assembly routes by electrophoresis and electron microscopy. We further analyzed two structure-switching behaviors of our rotaxanes, which are both mediated by DNA hybridization. In the first mechanism, the translational motion of the macrocycle can be triggered or halted at either terminus. In the second mechanism, the macrocycle can be elongated after completion of the rotaxane assembly, giving rise to a unique structure that is otherwise difficult to access.

  16. Synthesis, structure, and frequency-doubling effect of calcium cyanurate.

    PubMed

    Kalmutzki, Markus; Ströbele, Markus; Wackenhut, Frank; Meixner, Alfred J; Meyer, H-Jürgen

    2014-12-15

    Calcium cyanurate is synthesized by reacting calcium chloride with potassium cyanate following a solid-state reaction. The formation of the new compound Ca3(O3C3N3)2 (CCY), which occurs by the cyclotrimerization of cyanate ions, was examined thermoanalytically and the crystal structure was determined by single-crystal structure analysis. The structure of CCY is closely related to the structure of the well-known oxoborate β-BaB2O4 (BBO). Second harmonic generation (SHG) measurements on crystal powders show a higher SHG efficiency for CCY than for BBO by about one order of magnitude. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Benzotrifuranone: Synthesis, Structure, and Access to Polycyclic Heteroaromatics

    SciTech Connect

    Sumpter, Bobby G; Huang, Jingsong; Castellano, Ronald K; Lampkins, Andrew J; Baker, Matthew; Yan, Li; Abbound, Khalil A.

    2009-01-01

    Functionalized benzotrifurans can be accessed in one efficient acylation step from previously unreported benzotrifuranone. DFT calculations have confirmed the aromaticity of the heteroaromatic system and determined its electronic structure that is relevant to applications in materials and supramolecular chemistry.

  18. Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women.

    PubMed

    Hansen, Mette; Kongsgaard, Mads; Holm, Lars; Skovgaard, Dorthe; Magnusson, S Peter; Qvortrup, Klaus; Larsen, Jytte O; Aagaard, Per; Dahl, Morten; Serup, Annette; Frystyk, Jan; Flyvbjerg, Allan; Langberg, Henning; Kjaer, Michael

    2009-04-01

    The knowledge about the effect of estradiol on tendon connective tissue is limited. Therefore, we studied the influence of estradiol on tendon synthesis, structure, and biomechanical properties in postmenopausal women. Nonusers (control, n = 10) or habitual users of oral estradiol replacement therapy (ERT, n = 10) were studied at rest and in response to one-legged resistance exercise. Synthesis of tendon collagen was determined by stable isotope incorporation [fractional synthesis rate (FSR)] and microdialysis technique (NH(2)-terminal propeptide of type I collagen synthesis). Tendon area and fibril characteristics were determined by MRI and transmission electron microscopy, whereas tendon biomechanical properties were measured during isometric maximal voluntary contraction by ultrasound recording. Tendon FSR was markedly higher in ERT users (P < 0.001), whereas no group difference was seen in tendon NH(2)-terminal propeptide of type I collagen synthesis (P = 0.32). In ERT users, positive correlations between serum estradiol (s-estradiol) and tendon synthesis were observed, whereas change in tendon synthesis from rest to exercise was negatively correlated to s-estradiol. Tendon area, fibril density, fibril volume fraction, and fibril mean area did not differ between groups. However, the percentage of medium-sized fibrils was higher in ERT users (P < 0.05), whereas the percentage of large fibrils tended to be greater in control (P = 0.10). A lower Young's modulus (GPa/%) was found in ERT users (P < 0.05). In conclusion, estradiol administration was associated with higher tendon FSR and a higher relative number of smaller fibrils. Whereas this indicates stimulated collagen turnover in the resting state, collagen responses to exercise were negatively associated with s-estradiol. These results indicate a pivotal role for estradiol in maintaining homeostasis of female connective tissue.

  19. Enantiospecific Synthesis and Biological Investigations of a Nuphar Alkaloid: Proposed Structure of a Castoreum Component

    PubMed Central

    Seki, Hajime; Georg, Gunda I.

    2014-01-01

    An enantiospecific synthesis of a Nuphar alkaloid was achieved in 9 steps from N-Boc-(L)-proline. The alkaloid is a minor component of castoreum, the dried scent glands of the beaver. During the course of our study, the stereochemistry of three synthetic intermediates was verified by X-ray analysis, which contributes to resolving existing discrepancies among the literature reports regarding the synthesis of this particular compound. Based on our synthesis, we propose the structure of the natural product. Also, intrigued by castoreum’s therapeutic effect, which was used in ancient Greece and Rome for gynecological and other purposes, biological screening was conducted. We found that the alkaloid has affinity for the oxytocin receptor. PMID:25395879

  20. The Effects of Gravity on Combustion and Structure Formation During Synthesis of Advanced Materials

    NASA Technical Reports Server (NTRS)

    Varma, A.; Pelekh, A.; Mukasyan, A.

    1999-01-01

    Combustion in a variety of heterogeneous systems, leading to the synthesis of advanced materials, is characterized by high temperatures (2000-3500 K) and heating rates (up to 10(exp 6) K/s) at and ahead of the reaction front. These high temperatures generate liquids and gases which are subject to gravity-driven flow. The removal of such gravitational effects is likely to provide increased control of the reaction front, with a consequent improvement in control of the microstructure of the synthesized products. Thus, microgravity experiments can lead to major advances in the understanding of fundamental aspects of combustion and structure formation under the extreme conditions of the combustion synthesis wave. In addition, the specific features of microgravity environment allow one to produce unique materials, which cannot be obtained under terrestrial conditions. The general goals of the current research are: 1) to improve the understanding of fundamental phenomena taking place during combustion of heterogeneous systems, 2) to use low-gravity experiments for insight into the physics and chemistry of materials synthesis processes, and 3) based on the obtained knowledge, to optimize processing conditions for synthesis of advanced materials with desired microstructures and properties. This research follows logically from the results of investigations we have conducted in the framework of our previous grant on gravity influence on combustion synthesis (CS) of gasless systems. Prior work, by others and by us, has clearly demonstrated that gravity plays an important role during combustion synthesis of materials. The immediate tasks for the future are to quantitatively identify the nature of observed effects, and to create accurate local kinetic models of the processes, which can lead to a control of the microstructure and properties of the synthesized materials. In summary, this is the value of the proposed research. Based on our prior work, we focus on the fundamental

  1. The Effects of Gravity on Combustion and Structure Formation During Synthesis of Advanced Materials

    NASA Technical Reports Server (NTRS)

    Varma, A.; Pelekh, A.; Mukasyan, A.

    1999-01-01

    Combustion in a variety of heterogeneous systems, leading to the synthesis of advanced materials, is characterized by high temperatures (2000-3500 K) and heating rates (up to 10(exp 6) K/s) at and ahead of the reaction front. These high temperatures generate liquids and gases which are subject to gravity-driven flow. The removal of such gravitational effects is likely to provide increased control of the reaction front, with a consequent improvement in control of the microstructure of the synthesized products. Thus, microgravity experiments can lead to major advances in the understanding of fundamental aspects of combustion and structure formation under the extreme conditions of the combustion synthesis wave. In addition, the specific features of microgravity environment allow one to produce unique materials, which cannot be obtained under terrestrial conditions. The general goals of the current research are: 1) to improve the understanding of fundamental phenomena taking place during combustion of heterogeneous systems, 2) to use low-gravity experiments for insight into the physics and chemistry of materials synthesis processes, and 3) based on the obtained knowledge, to optimize processing conditions for synthesis of advanced materials with desired microstructures and properties. This research follows logically from the results of investigations we have conducted in the framework of our previous grant on gravity influence on combustion synthesis (CS) of gasless systems. Prior work, by others and by us, has clearly demonstrated that gravity plays an important role during combustion synthesis of materials. The immediate tasks for the future are to quantitatively identify the nature of observed effects, and to create accurate local kinetic models of the processes, which can lead to a control of the microstructure and properties of the synthesized materials. In summary, this is the value of the proposed research. Based on our prior work, we focus on the fundamental

  2. Synthesis and characterization of a new structure of gas hydrate

    SciTech Connect

    Tulk, Christopher A; Chakoumakos, Bryan C; Ehm, Lars; Klug, Dennis D; Parise, John B; Yang, Ling; Martin, Dave; Ripmeester, John; Moudrakovski, Igor; Ratcliffe, Chris

    2009-01-01

    Atoms and molecules 0.4 0.9 nm in diameter can be incorporated in the cages formed by hydrogen-bonded water molecules making up the crystalline solid clathrate hydrates. There are three structural families of these hydrates , known as sI, sII and sH, and the structure usually depends on the largest guest molecule in the hydrate. Species such as Ar, Kr, Xe and methane form sI or sII hydrate, sH is unique in that it requires both small and large cage guests for stability. All three structures, containing methane, other hydrocarbons, H2S and CO2, O2 and N2 have been found in the geosphere, with sI methane hydrate by far the most abundant. At high pressures (P > 0.7 kbar) small guests (Ar, Kr, Xe, methane) are also known to form sH hydrate with multiple occupancy of the largest cage in the hydrate. The high-pressure methane hydrate of sH has been proposed as playing a role in the outer solar system, including formation models for Titan , and yet another high pressure phase of methane has been reported , although its structure remains unknown. In this study, we report a new and unique hydrate structure that is derived from the high pressure sH hydrate of xenon. After quench recovery at ambient pressure and 77 K it shows considerable stability at low temperatures (T < 160 K) and is compositionally similar to the sI Xe clathrate starting material. This evidence of structural complexity in compositionally similar clathrate compounds indicates that thermodynamic pressure temperature conditions may not be the only important factor in structure determination, but also the reaction path may have an important effect.

  3. Synthesis and Monte Carlo Structure Determination of SSZ-77: A New Zeolite Topology

    SciTech Connect

    Earl,D.; Burton, A.; Rea, T.; Ong, K.; Deem, M.; Hwang, S.; Zones, S.

    2008-01-01

    A new molecular sieve topology has been determined from a multistage Monte Carlo computer simulation procedure using the program ZEFSAII. The material, SSZ-77, consists of alternating layers present in the RUT and AST topologies, and intergrowths may be possible in the way that this material grows. The product first arose from a synthesis where it appears that the degradation of the quaternary ammonium structure directing agent (SDA) produced the viable organo-guest molecule in the structure formation. The synthesis requires the use of Ge as well as Si as lattice components. In the absence of Ge, only RUT forms. An additional study was carried out to determine the suitable size of guest molecules in a series spanning trimethylamine to tetraethylammonium in the presence of benzyltrimethylammonium. It is found from NMR investigations that none of the larger molecules are occluded within the cages of the SSZ-77 structure, and that the primary occluded species is trimethylamine or tetramethylammonium.

  4. Hanford Site Environmental Restoration Program 1994 fiscal year work plan. Work breakdown structure 2.0: Revision 1

    SciTech Connect

    Not Available

    1993-12-22

    Site Management System (SMS) guidance requires a Fiscal Year Work Plan (FYWP) to be prepared for the Environmental Restoration (ER) Mission Area and all related programs. This revision is a complete update to cover the FY 1994 time period. This document describes the overall ER Missions Area and provides FYWP appendices for each of the following five program areas: Remedial Action (RA); Decontamination and Decommissioning (D&D); Project Management and Support (PM&S); Surveillance and Maintenance (S&M); and Disposal Facilities (DF).

  5. Revision of absolute configuration of enantiomeric (methylenecyclopropyl)carbinols obtained from (R)-(-)- and (S)-(+)-epichlorohydrin and methylenetriphenylphosphorane. Implications for reaction mechanism and improved synthesis of antiviral methylenecyclopropane analogues of nucleosides.

    PubMed

    Chen, Xinchao; Zemlicka, Jiri

    2002-01-11

    Absolute configurations of enantiomeric methylenecyclopropanecarbinols obtained by reaction of (R)- and (S)-epichlorohydrin 5 with methylenetriphenylphosphorane or resolution of the corresponding oxaphospholane 6 via a salt with L-(+)-tartaric acid and subsequent Wittig transformation with formaldehyde were revised. The (-)-oxaphospholane 6 has the S,S and (-)-(methylenecyclopropyl)carbinol (4) the R configuration. The configurations of (+)-6 and (+)-4 are then R,R and S, respectively. These assignments are in accord with an initial attack of phosphorane at the oxirane ring of epichlorohydrin. An improved preparation of key enantiomeric intermediates (R)-1a and (S)-1a, important for synthesis of antiviral purine methylenecyclopropane analogues of nucleosides, is also described.

  6. Synthesis and crystal structure analysis of uranyl triple acetates

    NASA Astrophysics Data System (ADS)

    Klepov, Vladislav V.; Serezhkina, Larisa B.; Serezhkin, Victor N.; Alekseev, Evgeny V.

    2016-12-01

    Single crystals of triple acetates NaR[UO2(CH3COO)3]3·6H2O (R=Mg, Co, Ni, Zn), well-known for their use as reagents for sodium determination, were grown from aqueous solutions and their structural and spectroscopic properties were studied. Crystal structures of the mentioned phases are based upon {Na[UO2(CH3COO)3]3}2- clusters and [R(H2O)6]2+ aqua-complexes. The cooling of a single crystal of NaMg[UO2(CH3COO)3]3·6H2O from 300 to 100 K leads to a phase transition from trigonal to monoclinic crystal system. Intermolecular interactions between the structural units and their mutual packing were studied and compared from the point of view of the stereoatomic model of crystal structures based on Voronoi-Dirichlet tessellation. Using this method we compared the crystal structures of the triple acetates with Na[UO2(CH3COO)3] and [R(H2O)6][UO2(CH3COO)3]2 and proposed reasons of triple acetates stability. Infrared and Raman spectra were collected and their bands were assigned.

  7. Synthesis and Characterization of Elastomeric Heptablock Terpolymers Structured by Crystallization

    SciTech Connect

    Alfonzo, C.Guillermo; Fleury, Guillaume; Chaffin, Kimberly A.; Bates, Frank S.

    2010-12-07

    We report the synthesis and characterization of fully saturated hydrocarbon block copolymer thermoplastic elastomers with competitive mechanical properties and attractive processing features. Block copolymers containing glassy poly(cyclohexylethylene) (C), elastomeric poly(ethylene-alt-propylene) (P), and semicrystalline poly(ethylene) (E) were produced in a CEC-P-CEC heptablock architecture, denoted XPX, by anionic polymerization and catalytic hydrogenation. The X blocks contain equal volume fractions of C and E, totaling 40%-60% of the material overall. All the XPX polymers are disordered above the melt temperature for E (T{sub m,E} {approx_equal} 95 C) as evidenced by SAXS and dynamic mechanical spectroscopy measurements. Cooling below T{sub m,E} results in crystallization of the E blocks, which induces microphase segregation of E, C, and P into a complex morphology with a continuous rubbery domain and randomly arranged hard domains as shown by TEM. This mechanism of segregation decouples the processing temperature from the XPX molecular weight up to a limiting value. Tensile mechanical testing (simple extension and cyclic loading) demonstrates that the tensile strength (ca. 30 MPa) and strain at break (>500%) are comparable to the behavior of CPC triblock thermoplastic elastomers of similar molecular weight and glass content. However, in the CPC materials, processability is constrained by the order-disorder transition temperature, limiting the applications of these materials. Elastic recovery of the XPX materials following seven cycles of tensile deformation is correlated with the fraction of X in the heptablock copolymer, and the residual strain approaches that of CPC when the fraction of hard blocks f{sub X} {le} 0.39.

  8. Strontium-copper selenite-chlorides: Synthesis and structural investigation

    SciTech Connect

    Berdonosov, Peter S.; Olenev, Andrei V.; Dolgikh, Valery A.

    2009-09-15

    Two new complex selenite-chlorides of strontium and copper Sr{sub 2}Cu(SeO{sub 3}){sub 2}Cl{sub 2} (I) and SrCu{sub 2}(SeO{sub 3}){sub 2}Cl{sub 2} (II) were obtained and characterized by X-ray diffraction technique, DTA and IR spectroscopy. Both compounds crystallize in the monoclinic system I: Sp. gr. P2{sub 1}/n, a=5.22996(3) A, b=6.50528(4) A, c=12.34518(7) A, beta=91.3643(2){sup o}, Z=2; II: Sp. gr. P2{sub 1}, a=7.1630(14) A, b=7.2070(14) A, c=8.0430(16) A, beta=95.92(3){sup o}, Z=2. Comparison of the crystal structure of (I) with the structures of Sr{sub 2}M(SeO{sub 3}){sub 2}Cl{sub 2} (M=Co, Ni) was performed. The substitution of strontium atom in the structure of (I) by Cu{sup 2+} ion with a 3d{sup 9} Jahn-Teller distorted surrounding leads to the lowering of the structure symmetry and to the appearance of the noncentrosymmetric structure of (II). The noncentrosymmetric character of the structure of (II) was confirmed by SHG signal (1.2 units relative to an alpha-quartz powder sample). - Graphical abstract: Sr{sub 2}Cu(SeO{sub 3}){sub 2}Cl{sub 2} and SrCu{sub 2}(SeO{sub 3}){sub 2}Cl{sub 2} were obtained and characterized by X-ray diffraction technique, DTA and IR spectroscopy.

  9. ACL Revision

    PubMed Central

    Costa-Paz, Matias; Dubois, Julieta Puig; Zicaro, Juan Pablo; Rasumoff, Alejandro; Yacuzzi, Carlos

    2017-01-01

    Objectives: The purpose of this study was to evaluate a series of patients one year after an ACL revision with clinical evaluation and MRI, to consider their condition before returning to sports activities. Methods: A descriptive, prospective and longitudinal study was performed. A series of patients who underwent an ACL revision between March 2014 and March 2015 were evaluated after one year post surgery. They were evaluated using the Lysholm score, IKDC, Tegner, artrometry and MRI (3.0 t). A signal pattern and osteointegration was determined in the MRI. Graft signal intensity of the ACL graft using the signal/noise quotient value (SNQ) was also determined to evaluate the ligamentatization process state. Results: A total of 18 male patients were evaluated with a mean age of 31 years old.Average scores were: Lysholm 88 points, IKDC 80 points, Pre-surgical Tegner 9 points and postoperative 4 points. Artrhometry (KT1000) at 20 newtons showed a side to side difference of less than 3 mm in 88%. Only 44% of patients returned to their previous sport activity one year after revision.The MRI showed a heterogeneous signal in neoligaments in 34% of patients. SNQ showed graft integration in only 28%. Synovial fluid was found in bone-graft interphase in 44% of tunnels, inferring partial osteointegration. The heterogeneous signal was present in 50% of patients who did not return to the previous sport level activity. (Fisher statistics: p = 0.043) There were no meaningful differences in patients with auto or allografts. Conclusion: Although the clinical evaluation was satisfactory, only 44% of patients returned to the previous level of sport activity one year after the ACL surgery. The ligamentatization process was found in 28% of knees evaluated with MRI one year later. Partial osteointegration is inferred in 44%. Results showed a meaningful relation between the signal of neoligaments in the MRI and the return to sport activity in said series of patients. MRI is a useful tool

  10. Synthesis, Structural, Electrical and Magnetic Studies of Ni- Ferrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Godbole, Bhavana; Badera, Nitu; Shrivastava, S. B.; Jain, Deepti; Chandra, L. S. Sharath; Ganesan, V.

    Mono-dispersed NiFe2O4 nanoparticles have been synthesized using a stable ferric salt of FeCl3 with co-precipitation technique, for study of their structural, morphological and magnetic properties. The XRD pattern conforms the formation of FCC structure with the lattice constant 8.31Ao. The crystallite size was found to increase with the bath temperature ranging from 33 nm to 55 nm. The AFM results revealed that uniform disc shaped particles were obtained. The resistivity measurements show a metal like to semiconductor transition, which depends on the size of the grains. The magnetic study reveals that saturation magnetization increases with the grain thickness.

  11. Structure/control synthesis with nonnegligible actuator mass

    NASA Technical Reports Server (NTRS)

    Zimmerman, David C.

    1990-01-01

    The simultaneous design of a structure/active control system is addressed in which the mass of the actuators required to implement the active control is considered. An algorithm for estimating the required actuator mass given the control law and the desired maneuver is presented. A nonlinear optimization algorithm is used to direct the design process. Results are given for the design of a L shaped structure where it is desired to minimize the line of sight pointing error after a worst case slew maneuver.

  12. Fischer-Tropsch Synthesis on Ceramic Monolith-Structured Catalysts

    SciTech Connect

    Wang, Yong; Liu, Wei

    2009-04-19

    This paper reports recent research results about impact of different catalyst bed configurations on FT reaction product distribution. A CoRe/γ-alumina catalyst is prepared in bulk particle form and tested in the packed bed reactor at a size of 60 to 100 mesh. The same catalyst is ball milled and coated on a ceramic monolith support structure of channel size about 1mm. The monolith catalyst module is tested in two different ways, as a whole piece and as well-defined channels. Steady-state reaction conversion is measured at various temperatures under constant H2/CO feed ratio of 2 and reactor pressure of 25 bar. Detailed product analysis is performed. Significant formation of wax is evident with the packed particle bed and with the monolith catalyst that is improperly packed. By contrast, the wax formation is not detected in the liquid product by confining the reactions inside the monolith channel. This study presents an important finding about the structured catalyst/reactor system that the product distribution highly depends on the way how the structured reactor is set up. Even if the same catalyst and same reaction conditions (T, P, H2/oil ratio) are used, hydrodynamics (or flow conditions) inside a structured channel can have a significant impact on the product distribution.

  13. Metal borohydrides and derivatives - synthesis, structure and properties.

    PubMed

    Paskevicius, Mark; Jepsen, Lars H; Schouwink, Pascal; Černý, Radovan; Ravnsbæk, Dorthe B; Filinchuk, Yaroslav; Dornheim, Martin; Besenbacher, Flemming; Jensen, Torben R

    2017-03-06

    A wide variety of metal borohydrides, MBH4, have been discovered and characterized during the past decade, revealing an extremely rich chemistry including fascinating structural flexibility and a wide range of compositions and physical properties. Metal borohydrides receive increasing interest within the energy storage field due to their extremely high hydrogen density and possible uses in batteries as solid state ion conductors. Recently, new types of physical properties have been explored in lanthanide-bearing borohydrides related to solid state phosphors and magnetic refrigeration. Two major classes of metal borohydride derivatives have also been discovered: anion-substituted compounds where the complex borohydride anion, BH4(-), is replaced by another anion, i.e. a halide or amide ion; and metal borohydrides modified with neutral molecules, such as NH3, NH3BH3, N2H4, etc. Here, we review new synthetic strategies along with structural, physical and chemical properties for metal borohydrides, revealing a number of new trends correlating composition, structure, bonding and thermal properties. These new trends provide general knowledge and may contribute to the design and discovery of new metal borohydrides with tailored properties towards the rational design of novel functional materials. This review also demonstrates that there is still room for discovering new combinations of light elements including boron and hydrogen, leading to complex hydrides with extreme flexibility in composition, structure and properties.

  14. Low-authority control synthesis for large space structures

    NASA Technical Reports Server (NTRS)

    Aubrun, J. N.; Margulies, G.

    1982-01-01

    The control of vibrations of large space structures by distributed sensors and actuators is studied. A procedure is developed for calculating the feedback loop gains required to achieve specified amounts of damping. For moderate damping (Low Authority Control) the procedure is purely algebraic, but it can be applied iteratively when larger amounts of damping are required and is generalized for arbitrary time invariant systems.

  15. Regional structural synthesis, Wyoming salient of western Overthrust Belt

    SciTech Connect

    Dixon, J.S.

    1983-08-01

    Surface geologic mapping, regional and high-density reflection seismic data and information from approximately 370 wells are combined to describe geometrically that area of the western Overthrust belt between the Snake River Plain and the Uinta uplift. Particular care has been taken to two-dimensionally verify interpretations of multiple thrust sheets by linear restoration. By establishing equivalence of pre-thrust lengths of affected beds, one can gain confidence in interpreted structural geometrics as well as generate data in regard to internal shortening and deformation intensity. Due to irresolvable geometric problems within sections, 47 cross sections were developed at roughly 6-mi (10 km) spacing to help verify changes in displacement or placement of key structural elements. Displacements of 0 to 32 mi (51 km) have been demonstrated, and both structure of faults and subcrop relations of Absaroka and younger thrusts are described. Jurassic to Paleocene (Sevier) thrusts were active across a previously deformed cratonic shelf terrane and interacted with active structural elements such as the Uinta uplift, Gros Ventre Range, and Moxa arch. Thrusts are progressively younger to the east, except for the Darby-Prospect pair in which the Darby system is younger.

  16. Synthesis and structural elucidation of a novel polymorph of alcaftadine

    NASA Astrophysics Data System (ADS)

    Pansuriya, Pramod B.; Maguire, Glenn E. M.; Friedrich, Holger B.

    2015-05-01

    In this study, we have synthesized and elucidated the structure of the H1 histamine antagonist, 2-(1-methylpiperidin-4-ylidene)-4,7-diazatricyclo[8.4.0.0(3,7)]tetradeca-1(14),3,5,10,12-pentaene-6-carbaldehyde in the solution and solid-state. We have also studied the thermal dilapidation of the compound. Solution structure analysis was achieved by employing NMR spectroscopy including 2D experiments NOESY, HSQC and HMBC, while solid state investigations were undertaken using SXRD, PXRD, TGA, DSC, and IR spectroscopy. For the first time the single crystal structure of alcaftadine has now been solved. Crystallographic data are as follows: monoclinic, Cc, a = 11.5694(6) Å, b = 14.5864(6) Å, c = 10.2688(4) Å, α = 90°, β = 111.793(3)°, γ = 90°, V = 1609.07(13) Å3, Z = 4. The Hirshfeld surface analyses also have been performed using the crystal structure.

  17. Synthesis, crystal structure and computational studies of 4-nitrobenzylphosphonic acid

    NASA Astrophysics Data System (ADS)

    Wilk, Magdalena; Jarzembska, Katarzyna N.; Janczak, Jan; Hoffmann, Józef; Videnova-Adrabinska, Veneta

    2014-09-01

    4-Nitrobenzylphosphonic acid (1a) has been synthesized and structurally characterized by vibrational spectroscopy (IR and Raman) and single-crystal X-ray diffraction. Additionally, Hirshfeld surface analysis and computational methods have been used to compare the intermolecular interactions in the crystal structures of 1a and its carboxylic analogue, 4-nitrobenzylcarboxylic acid (4-NBCA). The crystal structure analysis of 1a has revealed that the acid molecules are extended into helical chains along the b axis using one of the hydrogen bonds established between phosphonic groups. The second (P)Osbnd H⋯O(P) hydrogen bond cross-links the inversion-related chains to form a thick monolayer with phosphonic groups arranged inwards and aromatic rings outwards. The nitro groups serve to link the neighbouring monolayers by weak Csbnd H⋯O(N) hydrogen bonds. Computations have confirmed the great contribution of electrostatic interactions for the crystal lattice stability. The cohesive energy, computed for the crystal structure of 1a exceeds 200 kJ mol-1 in magnitude and is nearly twice as large as that of 4-NBCA. The calculated cohesive energy values have been further related to the results of thermal analyses.

  18. Phospholipase D as a catalyst: application in phospholipid synthesis, molecular structure and protein engineering.

    PubMed

    Damnjanović, Jasmina; Iwasaki, Yugo

    2013-09-01

    Phospholipase D (PLD) is a useful enzyme for its transphosphatidylation activity, which enables the enzymatic synthesis of various phospholipids (PLs). Many reports exist on PLD-mediated synthesis of natural and tailor-made PLs with functional head groups, from easily available lecithin or phosphatidylcholine. Early studies on PLD-mediated synthesis mainly employed enzymes of plant origin, which were later supplanted by ones from microorganisms, especially actinomycetes. Many PLDs are members of the PLD superfamily, having one or two copies of a signature sequence, HxKxxxxD or HKD motif, in the primary structures. PLD superfamily members share a common core structure, and thereby, a common catalytic mechanism. The catalysis proceeds via two-step reaction with the formation of phosphatidyl-enzyme intermediate. Both of the two catalytic His residues are critical in the reaction course, where one acts as a nucleophile, while the other functions as a general acid/base. PLD is being engineered to improve its activity and stability, alter head group specificity and further identify catalytically important residues. Since the knowledge on PLD enzymology is constantly expanding, this review focuses on recent advances in the field, regarding PLD-catalyzed synthesis of bioactive PLs, deeper understanding of substrate recognition and binding mechanism, altering substrate specificity, and improving thermostability. We introduced some of our recent results in combination with existing facts to further deepen the story on the nature of this useful enzyme. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  19. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    SciTech Connect

    Song, Xue-Qin Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-15

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.

  20. Structure revision and cytotoxic activity of marinamide and its methyl ester, novel alkaloids produced by co-cultures of two marine-derived mangrove endophytic fungi.

    PubMed

    Zhu, Feng; Chen, Guangying; Wu, Jingshu; Pan, Jiahui

    2013-01-01

    Marinamide (1) and its methyl ester (2) have been previously reported as pyrrolyl 1-isoquinolone alkaloids, which were produced by co-cultures of two marine-derived mangrove endophytic fungi from the South China Sea coast. Recrystallisation of methyl marinamide (2) from pyridine forms the known pesticide, quinolactacide (3). Treatment of 3 with methyl iodide to afford N-methyl quinolactacide (4) was identified by X-ray crystallography. Thus, the structures of 1 and 2 were revised from the previously reported pyrrolyl 1-isoquinolone structures to pyrrolyl 4-quinolone analogues. In the MTT assays, both 1 and 2 exhibited potent cytotoxic activity against HepG2, 95-D, MGC832 and HeLa tumour cell lines.

  1. Psychopathy and ethnicity: structural, item, and test generalizability of the Psychopathy Checklist--Revised (PCL-R) in Caucasian and African American Participants.

    PubMed

    Cooke, D J; Kosson, D S; Michie, C

    2001-12-01

    The Psychopathy Checklist--Revised (PCL-R) is an important measure in both applied and research settings. Evidence for its validity is mostly derived from male Caucasian participants. PCL-R ratings of 359 Caucasian and 356 African American participants were compared using confirmatory factor analysis (CFA) and item response theory (IRT) analyses. Previous research has indicated that 13 items of the PCL-R can be described by a 3-factor hierarchical model. This model was replicated in this sample. No cross-group difference in factor structure could be found using CFA; the structure of psychopathy is the same in both groups. IRT methods indicated significant but small differences in the performance of 5 of the 20 PCL-R items. No significant differential test functioning was found, indicating that the item differences canceled each other out. It is concluded that the PCL-R can be used, in an unbiased way, with African American participants.

  2. Bis(phosphine)boronium salts. Synthesis, structures and coordination chemistry.

    PubMed

    Shuttleworth, Timothy A; Huertos, Miguel A; Pernik, Indrek; Young, Rowan D; Weller, Andrew S

    2013-09-28

    The synthesis of a range of bis(phosphine)boronium salts is reported [(R2HP)2BH2][X] (R = Ph, (t)Bu, Cy) in which the counter anion is also varied (X(-) = Br(-), [OTf](-), [BAr(F)4](-), Ar(F) = 3,5-(CF3)2C6H3). Characterization in the solid-state by X-ray diffraction suggests there are weak hydrogen bonds between the PH units of the boronium cation and the anion (X(-) = Br(-), [OTf](-)), while solution NMR spectroscopy also reveals hydrogen bonding occurs in the order [BAr(F)4](-) < [OTf](-) < Br(-). [(Ph2HP)2BH2][BAr(F)4] reacts with RhH(PPh3)3, by elimination of H2, forming [Rh(κ(1),η-PPh2BH2·PPh2H)(PPh3)2][BAr(F)4] which shows a β-B-agostic interaction from the resulting base stabilised phosphino-borane ligand. Alternatively such ligands can be assembled directly on the metal centre by reaction of in situ generated {Rh(PPh3)3}(+) and Ph2HP·BH3 to afford [Rh(κ(1),η-PPh2BH2·PPh3)(PPh3)2][BAr(F)4], which was characterised by X-ray crystallography. Addition of H3B·PPh2H to the well-defined 16-electron "T-shaped" complex [Rh(P(i)Bu3)2(PPh3)][BAr(F)4] (characterised by X-ray crystallography) formed of a mixture of base-stabilised phosphino borane ligated complexes [Rh(κ(1),η-PR2BH2·PR3)(PR3)2][BAr(F)4] (R = (i)Bu or Ph). These last observations may lend clues to the formation of bis(phosphine)boronium salts in the catalytic dehydrocoupling reaction of phosphine boranes as mediated by Rh(I) compounds.

  3. Formal Synthesis of (±)-Tetrodotoxin via the Oxidative Amidation of a Phenol: On the Structure of the Sato Lactone.

    PubMed

    Xu, Sanjia; Ciufolini, Marco A

    2015-05-15

    A formal total synthesis of (±)-tetrodotoxin that relies on the bimolecular oxidative amidation of a phenol is described, and a structural correction of the Sato lactone, an important tetrodotoxin intermediate, is provided. This work lays the foundation for an ultimate enantioselective synthesis.

  4. Computer-aided methods for analysis and synthesis of supersonic cruise aircraft structures

    NASA Technical Reports Server (NTRS)

    Giles, G. L.

    1976-01-01

    Computer-aided methods are reviewed which are being developed by Langley Research Center in-house work and by related grants and contracts. Synthesis methods to size structural members to meet strength and stiffness (flutter) requirements are emphasized and described. Because of the strong interaction among the aerodynamic loads, structural stiffness, and member sizes of supersonic cruise aircraft structures, these methods are combined into systems of computer programs to perform design studies. The approaches used in organizing these systems to provide efficiency, flexibility of use in an iterative process, and ease of system modification are discussed.

  5. Wet-chemical synthesis and applications of non-layer structured two-dimensional nanomaterials

    PubMed Central

    Tan, Chaoliang; Zhang, Hua

    2015-01-01

    Non-layer structured nanomaterials with single- or few-layer thickness have two-dimensional sheet-like structures and possess intriguing properties. Recent years have seen major advances in development of a host of non-layer structured ultrathin two-dimensional nanomaterials such as noble metals, metal oxides and metal chalcogenides. The wet-chemical synthesis has emerged as the most promising route towards high-yield and mass production of such nanomaterials. These nanomaterials are now finding increasing applications in a wide range of areas including catalysis, energy production and storage, sensor and nanotherapy, to name but a few. PMID:26303763

  6. Synthesis, structural and spectroscopic investigations of nanostructured samarium oxalate crystals.

    PubMed

    Vimal, G; Mani, Kamal P; Biju, P R; Joseph, Cyriac; Unnikrishnan, N V; Ittyachen, M A

    2014-03-25

    Nanostructured samarium oxalate crystals were prepared via microwave assisted co-precipitation method. The crystal structure and morphology of the sample were analyzed using X-ray powder diffraction, Scanning electron microscopy and Transmission electron microscopy. The presence of functional groups is ascertained by Fourier transform infrared spectroscopy. Samarium oxalate nanocrystals of average size 20 nm were aggregated together to form nano-plate structure in sub-microrange. Detailed spectroscopic investigation of the prepared phosphor material was carried out by Judd-Ofelt analysis based on the UV-Visible-NIR absorption spectra and photoluminescence emission spectra. The analysis reveals that the transition from energy level (4)G5/2 to (6)H7/2 of Sm(3+) ion has maximum branching ratio and the corresponding orange emission can be used for display applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Synthesis and Molecular Structure of (99) Tc Corroles.

    PubMed

    Einrem, Rune F; Braband, Henrik; Fox, Thomas; Vazquez-Lima, Hugo; Alberto, Roger; Ghosh, Abhik

    2016-12-23

    The first (99) Tc corroles have been synthesized and fully characterized. A single-crystal X-ray structure of a (99) TcO triarylcorrole revealed nearly identical geometry parameters as the corresponding ReO structure. A significant spectral shift between the Soret maxima of TcO (410-413 nm) and ReO (438-441 nm) corroles was observed and, based on two-component spin-orbit ZORA TDDFT calculations, ascribed to relativistic effects in the Re case. The syntheses reported herein potentially pave the way toward (99m) Tc-porphyrinoid-based radiopharmaceuticals. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Synthesis of Nacre-Like Structures using Novel Fabrication Techniques

    DTIC Science & Technology

    2010-02-18

    objectives are 2-fold: (1) to fabricate a nano / micro -laminate that mimics the nacre in the abalone shell using engineering ceramic compositions and...fabricate and test a bioinspired material based on its structure. Our objectives are 2-fold: (1) to fabricate a nano / micro -laminate that mimics the...mechanical properties of the nano -constituents in cancellous bone,” First International Conference on Nanostructured Materials and Nanocomposites Kottayam

  9. Synthesis and surface structural characteristics of new polysiloxane xerogel

    NASA Astrophysics Data System (ADS)

    Zasukhin, A. S.; Neudachina, L. K.; Yatluk, Yu. G.; Adamova, L. V.; Osipova, V. A.; Gorbunova, E. M.; Moskaleva, Yu. S.; Larina, T. Yu.

    2011-03-01

    Pyridylethylaminopropylpolysiloxane xerogel (PEAPPSX) was synthesized by sol-gel technology. The composition of the substance was determined via elemental analysis and 1H NMR spectroscopy. The surface structural characteristics of the xerogel were determined by electron microscopy and low-temperature nitrogen sorption; thermal analysis was also performed. It was established that the content of functional groups in PEAPPSX was 2.43 mmol/g, and that xerogel is a mesoporous substance with a developed surface (121.71 m2/g).

  10. Synthesis and solution structure of the antimicrobial peptide protegrin-1.

    PubMed

    Aumelas, A; Mangoni, M; Roumestand, C; Chiche, L; Despaux, E; Grassy, G; Calas, B; Chavanieu, A

    1996-05-01

    Protegrins are members of a family of five Cys-rich, cationic antimicrobial peptides recently isolated from porcine cells. We have synthesised an 18-amino-acid peptide that corresponds to protegrin-1. After Cys oxidation, the peptide has bactericidal activity against gram-positive and gram-negative bacteria, similar to that described for the natural peptide. The solution structure of protegrin-1 was investigated by means of 1H-NMR spectroscopy in water and in (CD3)2SO, with distance-geometry and simulated-annealing calculations. The C6-C15 and C8-C13 disulfide pattern was determined on the basis of NMR-derived constraints. These two parallel disulfide bridges stabilised a beta-sheet structure which comprised two antiparallel strands (residues 5-9 and 12-16) linked by a distorted beta-turn (residues 9-12). The N-terminus and C-terminus were essentially disordered. The distribution of hydrophobic and hydrophilic residues at the peptide surface was found to be a structural feature shared with tachyplesin-1, a related peptide which displays cytolytic activity, and, to a lesser extent, with mammalian defensins. These findings led us to assume that the distribution pattern could be required for the cytolytic activity of these peptides.

  11. The synthesis and structural characterization of novel transition metal fluorides

    SciTech Connect

    Casteel, W.J. Jr.

    1992-09-01

    High purity KMF[sub 6] and K[sub 2]MF[sub 6] salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF[sub 6]. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF[sub 4] is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF[sub 4] type cell are derived from X-ray powder data for ReF[sub 4] and OsF[sub 4]. Fluoride ion capture from KAgF[sub 4] provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF[sub 3] and redetermination of the AuF[sub 3] structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF[sub 3] is the mixed valence compound Ag[sup II]Ag[sub 2][sup III]F[sub 8]. Several new salts containing the (Ag - F)[sub n][sup n+] chain cation are prepared. The first linear (Ag - F)[sub n][sup n+] chain is observed in AgF[sup +]BF[sub 4 [sup [minus

  12. Synthesis and structure of didysprosium complexes with a tetraketone

    NASA Astrophysics Data System (ADS)

    Yang, Luqin; Yang, Rudong

    1996-06-01

    Two novel didysprosium (Dy 2) complexes of 1,5-bis(1'-phenyl-3'-methyl-5'-pyrazolone-4')-1,5-pentanedione (H 2L), Dy 2L 3·2H 2O and Dy 2L 3·5DMF (DMF = dimethylformamide), have been synthesized. The crystal structure of Dy 2L 3·5DMF was determined by X-ray diffraction. Crystals are triclinic, space group P1¯, with a = 16.99(1), b = 17.970(9), c = 18.28(1) Å, α = 110.36(4), β = 101.47(6), γ = 111.11(5)°, V = 4533(9) Å 3, Mr = 2017.91, Z = 2, D x = 1.48 g cm -3, μ = 17.22 cm -1, F(000) = 2056, R = 0.074 with 3804 reflections used in the refinement. In the complex, each L bonds two dysprosium atoms with its two β-diketone groups. Two DMF solvent molecules bond to each dysprosium ion. The coordination number of the two dysprosium ions is eight. The eight oxygen atoms around the dysprosium ion make up a distorted square antiprism coordination polyhedron. The resonance structures of coordinated β-diketonates are also discussed. Different lanthanide ions may stabilize the specific structure.

  13. Synthesis, structure, and magnetic characterization of Cr4US8

    NASA Astrophysics Data System (ADS)

    Ward, Matthew D.; Chan, Ian Y.; Malliakas, Christos D.; Lee, Minseong; Choi, Eun Sang; Ibers, James A.

    2016-01-01

    The compound Cr4US8 has been synthesized at 1073 K and its crystal structure has been determined at 100 K. The structure is modulated with a two-fold commensurate supercell. The subcell may be indexed in an orthorhombic cell but weak supercell reflections lead to the monoclinic superspace group P21/c(α0γ)0s with two Cr sites, one U site, and four S sites. The structure comprises a three-dimensional framework of CrS6 octahedra with channels that are partially occupied by U atoms. Each U atom in these channels is coordinated by eight S atoms in a bicapped trigonal-prismatic arrangement. The magnetic behavior of Cr4US8 is complex. At temperatures above ~120 K at all measured fields, there is little difference between field-cooled and zero field-cooled data and χ(T) decreases monotonously with temperature, which is reminiscent of the Curie-Weiss law. At lower temperatures, the temperature dependence of χ(T) is complex and strongly dependent on the magnetic field strength.

  14. Potassium and magnesium succinatouranilates - Synthesis and crystal structure

    NASA Astrophysics Data System (ADS)

    Novikov, S. A.; Grigoriev, M. S.; Serezhkina, L. B.; Serezhkin, V. N.

    2017-04-01

    Single crystal X-ray diffraction has been applied to determine the structures of two new uranyl coordination polymers: K2[(UO2)2(C4H4O4)3] (1) and [Mg(H2O)6] [(UO2)2(C4H4O4)3]·2H2O (2), where C4H4O42- is succinate anion. Crystals of 1 and 2 contain polymeric complex anions [(UO2)2(C4H4O4)3]2- with the same A2Q023 crystallochemical formula (A=UO22+, Q02=C4O4H42-), and have layered (1) or chain (2) structure. It has been found, that conformation of succinate ions is one of the factors, which affects the structure of [(UO2)2(C4H4O4)3]2- anions. IR spectra of these new compounds are in good agreement with crystallographic data. Topological analysis of the uranium dicarboxylates with A2Q023 crystallochemical formula has shown the presence of five isomers which differ from each other in coordination sequences and / or dimensionality.

  15. Synthesis and characterization of carbon nanotube-polymer multilayer structures.

    PubMed

    Misra, Abha; Raney, Jordan R; De Nardo, Luigi; Craig, Anna E; Daraio, Chiara

    2011-10-25

    We develop lightweight, multilayer materials composed of alternating layers of poly dimethyl siloxane (PDMS) polymer and vertically aligned carbon nanotube (CNT) arrays, and characterize their mechanical response in compression. The CNT arrays used in the assembly are synthesized with graded mechanical properties along their thickness, and their use enables the creation of multilayer structures with low density (0.12-0.28 g/cm(3)). We test the mechanical response of structures composed of different numbers of CNT layers partially embedded in PDMS polymer, under quasi-static and dynamic loading. The resulting materials exhibit a hierarchical, fibrous structure with unique mechanical properties: They can sustain large compressive deformations (up to ∼0.8 strain) with a nearly complete recovery and present strain localization in selected sections of the materials. Energy absorption, as determined by the hysteresis observed in stress-strain curves, is found to be at least 3 orders of magnitude larger than that of natural and synthetic cellular materials of comparable density. Conductive bucky paper is included within the polymer interlayers. This allows the measurement of resistance variation as a function of applied stress, showing strong correlation with the observed strain localization in compression.

  16. Cementless acetabular revision: past, present, and future

    PubMed Central

    Pulido, Luis; Rachala, Sridhar R.

    2011-01-01

    Background Acetabular revision is probably the most difficult aspect of hip reconstructive surgery. Although the majority of acetabular revisions can be performed using an uncemented hemispherical acetabular device with ancillary fixation, patients with severe acetabular deficiencies and poor bone quality require more complex alternatives for revision. The limitations of traditional cementless acetabular implants has promoted the development of improved methods of fixation and revision techniques. Highly porous metals have been introduced for clinical use in arthroplasty surgery over the last decade. Their higher porosity and surface friction are ideal for acetabular revision, optimising biological fixation. The use of trabecular metal cups in acetabular revision has yielded excellent clinical results. Purpose This review focuses on the use of cementless implants for acetabular revision. The use of trabecular metal cups, augments, jumbo cups, oblong cups, cages, and structural grafting are also discussed. PMID:21234562

  17. Synthesis and Structure Characterization of Forsterite Single Crystal

    NASA Astrophysics Data System (ADS)

    Wang, C.; Jin, S.; Wang, X.; Liu, X.; Fleet, M. E.; Jin, Z.

    2006-12-01

    Forsterite (Mg2SiO4), the low-pressure polymorph of magnesium orthosilicate, is of great importance in the upper mantle due to its aboundance. Up to now, only powder samples of forsterite can be synthesized due to the difficulty of its crystal growth. Therefore, the exact crystal structure of forsterite is still an open question. The crystal structure of forsterite was firstly studied in 1926 by Brown and Bragg. Numerous experimental investigations have been performed in order to get the structure of the olivine group minerals at ambient conditions and a variety of temperature and pressures by using the advent of the computer, the single crystal diffractometer and the diamond cell. However, there are still considerable uncertaintes regarding the accuracy of its unit-cell parameter values. In this study, we synthesized for the first time high quality single crystals of forsterite using the Quickpress piston-cylinder apparatus. The single crystal of forsterite was synthesized by direct reaction of stoichiometric amounts of MgO and amorphous SiO2 (Alfa Aesar, 99.999%) in the presence of ~10-11 wt% distilled water at 2.0GPa, 1723 K for 12h. A colorless single crystal of Mg2SiO4 with size dimensions 0.16×0.11×0.04 mm was selected for single crystal X-ray diffraction analysis. The intensity data were collected with a Rigaku R-AXIS RAPID IP diffractometer by oscillation scans using graphite- monochromated Mo-K?0?6?0?6?7677?0?6?0?6?7699 radiation (λ=0.71073 Å). Cell refinement and data reduction were accomplished with RAPID AUTO program. The crystal structure was solved by direct methods with the SHELXL crystallographic software package. Single crystal X-ray diffraction analysis shows a crystal structure of orthorhombic space group Pnma (No. 62) with a = 10.2073(11) Å, b = 5.9863(5) Å, c = 4.7611(4) Å and Z = 4. Our new data provides new constraints for theoretical investigations of the physical and chemistry properties and behaviors of forsterite under various

  18. Microwave prompted multigram synthesis, structural determination, and photo-antiproliferative activity of fluorinated 4-hydroxyquinolinones.

    PubMed

    Arya, Kapil; Agarwal, Manish

    2007-01-01

    3-Unsubstituted 4-hydroxyquinolin-2(1H)-one containing F and CF(3) substituent in ring is important pharmacological and synthetic target and basic synthones for a number of antibacterial fluoroquinolones and is promising potent and selective glycine site NMDA receptors. A simple facile one-step microwave enhanced multigram synthesis of such fluorinated quinolones in reasonable purity has been developed in excellent yield (85-94%) in 3-5 min, whereas conventional synthesis required the harsh conditions, long reaction period with use of environmentally unacceptable regents giving the required product in lower yield. The phototoxicity as well as the cytotoxic activities of the title compounds are evaluated against leukemia- and adenocarcinoma-derived cell lines in comparison to the normal human keratinocytes. Structure-activity relationships between the chemical structures and the antimycobacterial, antifungal activity of the evaluated compounds are also discussed.

  19. Synthesis, Structural Characterization, and Bioactivity of the Stable Peptide RCB-1 from Ricinus communis.

    PubMed

    Boldbaatar, Delgerbat; Gunasekera, Sunithi; El-Seedi, Hesham R; Göransson, Ulf

    2015-11-25

    The Ricinus communis biomarker peptides RCB-1 to -3 comprise homologous sequences of 19 (RCB-1) or 18 (RCB-2 and -3) amino acid residues. They all include four cysteine moieties, which form two disulfide bonds. However, neither the 3D structure nor the biological activity of any of these peptides is known. The synthesis of RCB-1, using microwave-assisted, Fmoc-based solid-phase peptide synthesis, and a method for its oxidative folding are reported. The tertiary structure of RCB-1, subsequently established using solution-state NMR, reveals a twisted loop fold with antiparallel β-sheets reinforced by the two disulfide bonds. Moreover, RCB-1 was tested for antibacterial, antifungal, and cytotoxic activity, as well as in a serum stability assay, in which it proved to be remarkably stable.

  20. Advances on Semisynthesis, Total Synthesis, and Structure-Activity Relationships of Honokiol and Magnolol Derivatives.

    PubMed

    Yang, Chun; Zhi, Xiaoyan; Xu, Hui

    2016-01-01

    Honokiol and magnolol (an isomer of honokiol) are small-molecule polyphenols isolated from the barks of Magnolia officinalis, which have been widely used in traditional Chinese and Japanese medicines. In the last decade, a variety of biological properties of honokiol and magnolol (e.g., anti-oxidativity, antitumor activity, anti-depressant activity, anti-inflammatory activity, neuroprotective activity, anti-diabetic activity, antiviral activity, and antimicrobial activity) have been reported. Meanwhile, certain mechanisms of action of some biological activities were also investigated. Moreover, many analogs of honokiol and magnolol were prepared by structural modification or total synthesis, and some exhibited very potent pharmacological activities with improved water solubility. Therefore, the present review will provide a systematic coverage on recent developments of honokiol and magnolol derivatives in regard to semisynthesis, total synthesis, and structure-activity relationships from 2000 up to now.

  1. Simulating Cellulose Structure, Properties, Thermodynamics, Synthesis, and Deconstruction with Atomistic and Coarse-Grain Models

    SciTech Connect

    Crowley, M. F.; Matthews, J.; Beckham, G.; Bomble, Y.; Hynninen, A. P.; Ciesielski, P. F.

    2012-01-01

    Cellulose is still a mysterious polymer in many ways: structure of microfibrils, thermodynamics of synthesis and degradation, and interactions with other plant cell wall components. Our aim is to uncover the details and mechanisms of cellulose digestion and synthesis. We report the details of the structure of cellulose 1-beta under several temperature conditions and report here the results of these studies and connections to experimental measurements and the measurement in-silico the free energy of decrystallization of several morphologies of cellulose. In spatially large modeling, we show the most recent work of mapping atomistic and coarse-grain models into tomographic images of cellulose and extreme coarse-grain modeling of interactions of large cellulase complexes with microfibrils. We discuss the difficulties of modeling cellulose and suggest future work both experimental and theoretical to increase our understanding of cellulose and our ability to use it as a raw material for fuels and materials.

  2. Total synthesis of albicidin: a lead structure from Xanthomonas albilineans for potent antibacterial gyrase inhibitors.

    PubMed

    Kretz, Julian; Kerwat, Dennis; Schubert, Vivien; Grätz, Stefan; Pesic, Alexander; Semsary, Siamak; Cociancich, Stéphane; Royer, Monique; Süssmuth, Roderich D

    2015-02-02

    The peptide antibiotic albicidin, which is synthesized by the plant pathogenic bacterium Xanthomonas albilineans, displays remarkable antibacterial activity against various Gram-positive and Gram-negative microorganisms. The low amounts of albicidin obtainable from the producing organism or through heterologous expression are limiting factors in providing sufficient material for bioactivity profiling and structure-activity studies. Therefore, we developed a convergent total synthesis route toward albicidin. The unexpectedly difficult formation of amide bonds between the aromatic amino acids was achieved through a triphosgene-mediated coupling strategy. The herein presented synthesis of albicidin confirms the previously determined chemical structure and underlines the extraordinary antibacterial activity of this compound. The synthetic protocol will provide multigram amounts of albicidin for further profiling of its drug properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Synthesis conditions and sintered ZrW2O8 structure

    NASA Astrophysics Data System (ADS)

    Dedova, Elena S.; Gubanov, Alexander I.; Filatov, Eugeny Y.; Kardash, Tatyana Y.; Kulkov, Sergei N.

    2016-11-01

    This paper discusses synthesis condition effect on the structure and morphology of ZrW2O8 using thermal decomposition of precursor ZrW2O7(OH,Cl)2.2H2O prepared by hydrothermal method. It was observed that for hydrothermal precursor synthesis the optimal concentration of hydrochloric acid in the reaction mixture was about 2.3 M and sintering time amounted to 36 hours. The precursor morphology was in the form of needle-like particles and loose irregular shape agglomerates. The pure nanoscale ZrW2O8 powder was obtained by precursor heating at 570°C for 1 hour and has needle-like particles with an intrinsic block structure. The average block size was 50 nm. The average transverse size was less than 1 µm, the longitudinal particle size varied from 500 to 5000 nm.

  4. Synthesis of a specified, silica molecular sieve by using computationally predicted organic structure-directing agents.

    PubMed

    Schmidt, Joel E; Deem, Michael W; Davis, Mark E

    2014-08-04

    Crystalline molecular sieves are used in numerous applications, where the properties exploited for each technology are the direct consequence of structural features. New materials are typically discovered by trial and error, and in many cases, organic structure-directing agents (OSDAs) are used to direct their formation. Here, we report the first successful synthesis of a specified molecular sieve through the use of an OSDA that was predicted from a recently developed computational method that constructs chemically synthesizable OSDAs. Pentamethylimidazolium is computationally predicted to have the largest stabilization energy in the STW framework, and is experimentally shown to strongly direct the synthesis of pure-silica STW. Other OSDAs with lower stabilization energies did not form STW. The general method demonstrated here to create STW may lead to new, simpler OSDAs for existing frameworks and provide a way to predict OSDAs for desired, theoretical frameworks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Synthesis and characterization of JBW structure and its thermal transformation

    SciTech Connect

    Hegazy, Eman Z.; Kosa, Samia A.; Abd El Maksod, Islam Hamdy

    2012-12-15

    In this paper, JBW zeolite prepared from Egyptian kaolin was investigated by means of XRD, IR, SEM, EDX and ion exchange of some heavy metals. Adsorption isotherms were used to investigate the structure and properties of the prepared zeolite. XRD analysis showed that the JBW was a pure crystalline phase with orthorhombic crystal symmetry. Thermal treatment showed that the JBW transformed into the It-Carn phase at 1000 Degree-Sign C through an intermediate crystalline alumino silicate phase. SEM images showed that the JBW crystallised in a cylindrical shape. However, spherical agglomerates were observed at lower magnifications. The ion exchange isotherms with Cu{sup 2+}, Ni{sup 2+} and Co{sup 2+} were found to follow a Freundlich isotherm. In addition, it shows higher affinity towards Cu{sup 2+} than other ions. - Graphical abstract: JBW zeolite structure was prepared from Egyptian kaolin and characterised. XRD analysis showed that the JBW was a pure crystalline phase with orthorhombic crystal symmetry. Thermal treatment showed that the JBW transformed into the It-Carn phase at 1000 Degree-Sign C through an intermediate crystalline alumino silicate phase. Highlights: Black-Right-Pointing-Pointer Egyptian kaolin was successfully used to prepare pure phase of JBW Structure. Black-Right-Pointing-Pointer JBW is stable till <300 Degree-Sign C. Black-Right-Pointing-Pointer JBW phase crystallizes as cylindrical shape but agglomerates in a Nano spherical shape. Black-Right-Pointing-Pointer The ion exchange isotherms of Cu{sup 2+}, Ni{sup 2+}, and Co{sup 2+} followed up Freundlich isotherm. Black-Right-Pointing-Pointer Selectivity towards Cu{sup 2+} is much higher than Co{sup 2+} or Ni{sup 2+}.

  6. Hydroflux synthesis and crystal structure of new lanthanide tungstate oxyhydroxides

    NASA Astrophysics Data System (ADS)

    Latshaw, Allison M.; Smith, Mark D.; Chance, W. Michael; zur Loye, Hans-Conrad

    2015-04-01

    Single crystals of Na5Ln(OH)6WO4 where Ln = Er, Tm, and Yb were grown out of a NaOH hydroflux. The crystals were characterized by single crystal X-ray diffraction and were found to crystallize in the monoclinic space group I2/a. The lattice parameter ranges for the three structures are a = 11.2024(7) Å-11.2412(6) Å, b = 16.1850(10) Å-16.2220(10) Å, and c = 11.9913(7) Å-12.0323(7) Å while the β angle range is 101.999(2)°-102.025(2)°.

  7. Long tailed cage amines: Synthesis, metal complexation, and structure

    SciTech Connect

    Dittrich, Birger; Harrowfield, Jack M.; Koutsantonis, George A.; Nealon, Gareth L.; Skelton, Brian W.

    2011-12-09

    The generation of amphiphiles derived from macrobicyclic hexamines of the 'sarcophagine' class can be prepared through efficient and selective reactions involving the reductive alkylation, using long-chain aldehydes, of amino-functionalized sarcophagines when bound to Cu(II) or Mg(II). The Mg(II) pathway is particularly convenient for the ultimate isolation of the free ligands, which can then be used to form metalloamphiphiles with a variety of metal ions. Structural studies have been made of one of the free (protonated) ligands and some of their complexes.

  8. Topology synthesis of planar ground structures for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Danzi, Francesco; Gibert, James; Cestino, Enrico; Frulla, Giacomo

    2017-04-01

    In this manuscript, we investigate the use topology optimization to design planar resonators with modal fre- quencies that occur at 1 : n ratios for kinetic energy scavenging of ambient vibrations that exhibit at least two frequency components. Furthermore, we are interested in excitations with a fundamental component containing large amounts of energy and secondary component with smaller energy content. This phenomenon is often seen in rotary machines; their frequency spectrum exhibits peaks on multiple harmonics, where the energy is primarily contained in the rotation frequency of the device. Several theoretical resonators are known to exhibit modal frequencies that at integer multiples 1:2 or 1:3. However, designing manufacturable resonators for other geometries is still a daunting task. With this goal in mind, we utilize topology optimization to determine the layout of the resonator. We formulate the problem in its non-dimensional form, eliminating the constraint on the allowable frequency. The frequency can be obtained a posteriori by means of linear scaling. Conversely, to previous research, which use the clamped beam as initial guess, we synthesize the final shape starting from a ground structure (or structural universe) and remove of the unnecessary beams from the initial guess by means of a graph-based filtering scheme. The algorithm determines the simplest structure that gives the desired frequency's ratio. Within the optimization, the structural design is accomplished by a linear FE analysis. The optimization reveals several trends, the most notable being that having members connected orthogonally as in the L-shaped resonator is not the preferred topology of this devices. In order to fully explore the angle of orientation of connected members on the modal characteristics of the device; we derive a reduced-order model that allows a bifurcation analysis on the effect of member orientation on modal frequency. Furthermore, the reduced order approximation is

  9. A uranium (VI) complex: Synthesis, structural and thermal kinetic analysis

    NASA Astrophysics Data System (ADS)

    Goel, Nidhi

    2016-08-01

    A new complex [UO2(2,6-DNP)2phen] (1) (2,6-DNP = 2,6-dinitrophenol, phen = 1,10-phenanthroline) was synthesized, and identified by elemental analysis, IR, Powder XRD and single crystal X-ray crystallography. Crystal structure provides the abundant information's about the bonding and geometry around the U(VI) metal center. The thermal decomposition was studied by TG-DSC, and the kinetics of thermolysis was investigated by applying model fitting as well as isoconversional methods. Explosion delay measurement (De) was also evaluated to determine the response of this complex under the condition of rapid heating.

  10. Synthesis and structural characterization of oaklin-catechins.

    PubMed

    Sousa, André; Fernandes, Ana; Mateus, Nuno; De Freitas, Victor

    2012-02-15

    Condensation reactions of procyanidin dimer B4 with two representative oak wood cinnamic aldehydes (coniferaldehyde and sinapaldehyde) were conducted in winelike model solutions. Coniferaldehyde led to the formation of guaiacylcatechin-pyrylium-catechin (GCP-catechin, 737 m/z), whereas sinapaldehyde led to the formation of syringylcatechin-pyrylium-catechin (SCP-catechin, 767 m/z). The former was also structurally characterized by 1D and 2D NMR, allowing an elucidation of the formation mechanism of these oaklin-catechin adducts and demonstrating the importance of procyanidins in the formation of colored compounds through the reaction with cinnamic aldehydes extracted from oaks during storage.

  11. Chemical synthesis and structure elucidation of bovine kappa-casein (1-44).

    PubMed

    Bansal, Paramjit S; Grieve, Paul A; Marschke, Ronald J; Daly, Norelle L; McGhie, Emily; Craik, David J; Alewood, Paul F

    2006-02-24

    The caseins (alphas1, alphas2, beta, and kappa) are phosphoproteins present in bovine milk that have been studied for over a century and whose structures remain obscure. Here we describe the chemical synthesis and structure elucidation of the N-terminal segment (1-44) of bovine kappa-casein, the protein which maintains the micellar structure of the caseins. kappa-Casein (1-44) was synthesised by highly optimised Boc solid-phase peptide chemistry and characterised by mass spectrometry. Structure elucidation was carried out by circular dichroism and nuclear magnetic resonance spectroscopy. CD analysis demonstrated that the segment was ill defined in aqueous medium but in 30% trifluoroethanol it exhibited considerable helical structure. Further, NMR analysis showed the presence of a helical segment containing 26 residues which extends from Pro8 to Arg34. This is the first report which demonstrates extensive secondary structure within the casein class of proteins.

  12. Spherical silica micro/nanomaterials with hierarchical structures: synthesis and applications.

    PubMed

    Du, Xin; He, Junhui

    2011-10-05

    This paper reviews the progress made recently in synthesis and applications of spherical silica micro/nanomaterials with multilevel (hierarchical) structures. The spherical silica micro/nanomaterials with hierarchical structures are classified into four main structural categories that include (1) hollow mesoporous spheres, (2) core-in-(hollow porous shell) spheres, (3) hollow spheres with multiple porous shells and (4) hierarchically porous spheres. Due to the complex structures and being focused on spherical silica micro/nanomaterials, some novel methods based on the combination of two routine methods or two surfactants, and some special synthetic strategies are proposed to produce the spherical silica micro/nanomaterials with hierarchical structures. Compared with the same-sized solid, porous or hollow silica spheres, these fantastic spherical silica micro/nanomaterials with hierarchical structures exhibit enhanced properties which may enable them to be used in broad and promising applications as ideal scaffolds (carriers) for biological, medical, and catalytic applications.

  13. Chemical synthesis and structure elucidation of bovine {kappa}-casein (1-44)

    SciTech Connect

    Bansal, Paramjit S.; Grieve, Paul A.; Marschke, Ronald J.; Daly, Norelle L.; McGhie, Emily; Craik, David J.; Alewood, Paul F. . E-mail: p.alewood@imb.uq.edu.au

    2006-02-24

    The caseins ({alpha}{sub s1}, {alpha}{sub s2}, {beta}, and {kappa}) are phosphoproteins present in bovine milk that have been studied for over a century and whose structures remain obscure. Here we describe the chemical synthesis and structure elucidation of the N-terminal segment (1-44) of bovine {kappa}-casein, the protein which maintains the micellar structure of the caseins. {kappa}-Casein (1-44) was synthesised by highly optimised Boc solid-phase peptide chemistry and characterised by mass spectrometry. Structure elucidation was carried out by circular dichroism and nuclear magnetic resonance spectroscopy. CD analysis demonstrated that the segment was ill defined in aqueous medium but in 30% trifluoroethanol it exhibited considerable helical structure. Further, NMR analysis showed the presence of a helical segment containing 26 residues which extends from Pro{sup 8} to Arg{sup 34}. This is First report which demonstrates extensive secondary structure within the casein class of proteins.

  14. Process signatures in glatiramer acetate synthesis: structural and functional relationships.

    PubMed

    Campos-García, Víctor R; Herrera-Fernández, Daniel; Espinosa-de la Garza, Carlos E; González, German; Vallejo-Castillo, Luis; Avila, Sandra; Muñoz-García, Leslie; Medina-Rivero, Emilio; Pérez, Néstor O; Gracia-Mora, Isabel; Pérez-Tapia, Sonia Mayra; Salazar-Ceballos, Rodolfo; Pavón, Lenin; Flores-Ortiz, Luis F

    2017-09-21

    Glatiramer Acetate (GA) is an immunomodulatory medicine approved for the treatment of multiple sclerosis, whose mechanisms of action are yet to be fully elucidated. GA is comprised of a complex mixture of polypeptides with different amino acid sequences and structures. The lack of sensible information about physicochemical characteristics of GA has contributed to its comprehensiveness complexity. Consequently, an unambiguous determination of distinctive attributes that define GA is of highest relevance towards dissecting its identity. Herein we conducted a study of characteristic GA heterogeneities throughout its manufacturing process (process signatures), revealing a strong impact of critical process parameters (CPPs) on the reactivity of amino acid precursors; reaction initiation and polymerization velocities; and peptide solubility, susceptibility to hydrolysis, and size-exclusion properties. Further, distinctive GA heterogeneities were correlated to defined immunological and toxicological profiles, revealing that GA possesses a unique repertoire of active constituents (epitopes) responsible of its immunological responses, whose modification lead to altered profiles. This novel approach established CPPs influence on intact GA peptide mixture, whose physicochemical identity cannot longer rely on reduced properties (based on complete or partial GA degradation), providing advanced knowledge on GA structural and functional relationships to ensure a consistent manufacturing of safe and effective products.

  15. Regional structural synthesis Wyoming salient of Western Overthrust Belt

    SciTech Connect

    Dixon, J.S.

    1982-10-01

    Surface geologic mapping, regional and high-density reflection seismic data nd information from approximately 370 wells ahve been combined to describe geometrically that area of the Western Overthrust belt between the Snake River plain and the Uinta uplift. Particular care has been taken to verify two-dimensional interpretations of multiple thrust sheets by linear restoration. By establishing equivalence of pre-thrust lenghts of affected beds, one can gain confidence in interpreted structural geometries, as well as generate data in regard to internal shortening and deformation intensity. Because of irresoluable geometric problems within sections, 47 cross sections were developed at rougly 6-mi (10 km) spacing to help verify changes in displacement or placement of key structurl elements. Displacements of 0 to 32 mi (o to 51 km) have been demonstrated. Jurassic to Paleocene (Sevier) thrusts were active across a previously deformed (Sevier) thrusts were active across a previously deformed cratonic shelf terrane and interacted with active structural elements such as the uinta uplift, Gros Ventre Range, and Moxa arch. Thrusts are progressively younger to ehe east except for the Darby-Prospect pair in which the Darby system is younger.

  16. Unsymmetrical pyrene-fused phthalocyanine derivatives: synthesis, structure, and properties.

    PubMed

    Pan, Houhe; Chen, Chao; Wang, Kang; Li, Wenjun; Jiang, Jianzhuang

    2015-02-16

    Novel pyrene-fused unsymmetrical phthalocyanine derivatives 2,3,9,10,16,17-hexakis(2,6-dimethylphenoxy)-22,25-diaza(2,7-di-tert-butylpyrene)[4,5]phthalocyaninato zinc complex Zn[Pc(Pz-pyrene)(OC8 H9 )6 ] (1) and 2,3,9,10-tra(2,6-dimethylphenoxy)-15,18,22,25-traza(2,7-di-tert-butylpyrene)[4,5]phthalocyaninato zinc compound Zn[Pc(Pz-pyrene)2 (OC8 H9 )4 ] (2) were isolated for the first time. These unsymmetrical pyrene-fused phthalocyanine derivatives have been characterized by a wide range of spectroscopic and electrochemical methods. In particular, the pyrene-fused phthalocyanine structure was unambiguously revealed on the basis of single crystal X-ray diffraction analysis of 1, representing the first structurally characterized phthalocyanine derivative fused with an aromatic moiety larger than benzene. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Hydrothermal Synthesis and Structure of Neptunium(V) Oxide

    SciTech Connect

    Forbes, Tori Z.; Burns, Peter C.; Soderholm, L. |; Skanthakumar, S.

    2007-07-01

    Single crystals of Np{sub 2}O{sub 5} have been synthesized by low-temperature hydrothermal reaction of a (NpO{sub 2}){sup +} stock solution with natural calcite crystals. The structure of Np{sub 2}O{sub 5} was solved by direct methods and refined on the basis of F{sup 2} for all unique data collected on a Bruker X-ray diffractometer equipped with an APEX II CCD detector. Np{sub 2}O{sub 5} is monoclinic, space group P2/c, with a = 8.168(2) A, b = 6.584(1) A, c = 9.3130(2) A, {beta} = 116.01(1) deg., V = 449.8(2) A{sup 3}, and Z = 1. The structure contains chains of edge-sharing neptunyl pentagonal bi-pyramids linked into sheets through cation-cation interactions with distorted neptunyl square bi-pyramids. Additional cation-cation interactions connect the sheets into a three-dimensional framework. The formation of Np{sub 2}O{sub 5} on the surface of calcite crystals has important implications for the precipitation of isolated neptunyl phases in natural aqueous systems. (authors)

  18. Facile synthesis and structure characterization of hexagonal tungsten bronzes crystals

    NASA Astrophysics Data System (ADS)

    Lee, Jiann-Shing; Liu, Hao-Chuan; Peng, Gao-De; Tseng, Yawteng

    2017-05-01

    A facile molten-salt route was used to synthesize hexagonal Cs0.33WO3, Rb0.33WO3 and K0.30WO3 crystals. The three isostructural compounds were successfully prepared from the reaction of MxWO3 powders (M = Cs, Rb, K) in the CsCl/NaCl, RbCl/NaCl and KCl/NaCl fluxes, respectively. The structure determination and refinement, based on single-crystal X-ray diffraction data, are in agreement with previous works, possessing space group P63/mcm. The a and c parameters vary non-linearly with increasing radii of the M+ cations (rM) that is coordinated to twelve oxygen atoms. Both the volumes of unit-cell and WO6 octahedra vary linearly with rM, which become smaller from Cs0.33WO3 to K0.30WO3. The distortion of WO6 octahedra as well as isotropic displacement parameters increases from Cs0.33WO3 to K0.30WO3. The geometry of the WO6 octahedron becomes more regular with increasing rM. These structural trends arise from the effective size of the M+ cation.

  19. A novel series of thiosemicarbazone drugs: From synthesis to structure

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Hossein Pasha; Hadi, Jabbar S.; Alsalim, Tahseen A.; Ghali, Thaer S.; Bolandnazar, Zeinab

    2015-02-01

    A new series of thiosemicarbazones (TSCs) and their 1,3,4-thiadiazolines (TDZs) containing acetamide group have been synthesized from thiosemicarbazide compounds by the reaction of TSCs with cyclic ketones as well as aromatic aldehydes. The structures of newly synthesized 1,3,4-thiadiazole derivatives obtained by heterocyclization of the TSCs with acetic anhydride were experimentally characterized by spectral methods using IR, 1H NMR, 13C NMR and mass spectroscopic methods. Furthermore, the structural, thermodynamic, and electronic properties of the studied compounds were also studied theoretically by performing Density Functional Theory (DFT) to access reliable results to the experimental values. The molecular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and Mulliken atomic charges of the studied compounds have been calculated at the B3LYP method and standard 6-31+G(d,p) basis set starting from optimized geometry. The theoretical 13C chemical shift results were also calculated using the gauge independent atomic orbital (GIAO) approach and their respective linear correlations were obtained.

  20. Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

    PubMed Central

    Matsui, Daisuke; Mayumi, Koichi

    2015-01-01

    Summary A significantly soft and tough nanocomposite gel was realized by a novel network formed using cyclodextrin-based polyrotaxanes. Covalent bond formation between the cyclic components of polyrotaxanes and the surface of silica nanoparticles (15 nm diameter) resulted in an infinite network structure without direct bonds between the main chain polymer and the silica. Small-angle X-ray scattering revealed that the homogeneous distribution of silica nanoparticles in solution was maintained in the gel state. Such homogeneous nanocomposite gels were obtained with at least 30 wt % silica content, and the Young’s modulus increased with silica content. Gelation did not occur without silica. This suggests that the silica nanoparticles behave as cross-linkers. Viscoelastic measurements of the nanocomposite gels showed no stress relaxation regardless of the silica content for <20% compression strain, indicating an infinite stable network without physical cross-links that have finite lifetime. On the other hand, the infinite network exhibited an abnormally low Young’s modulus, ~1 kPa, which is not explainable by traditional rubber theory. In addition, the composite gels were tough enough to completely maintain the network structure under 80% compression strain. These toughness and softness properties are attributable to both the characteristic sliding of polymer chains through the immobilized cyclodextrins on the silica nanoparticle and the entropic contribution of the cyclic components to the elasticity of the gels. PMID:26664642

  1. One dimensional coordination polymers: Synthesis, crystal structures and spectroscopic properties

    NASA Astrophysics Data System (ADS)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur

    2016-11-01

    Two new one dimensional (1D) cyanide complexes, namely [M(4-aepy)2(H2O)2][Pt(CN)4], (4-aepy = 4-(2-aminoethyl)pyridine M = Cu(II) (1) or Zn(II) (2)), have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal and elemental analyses techniques. The crystallographic analyses reveal that 1 and 2 are isomorphous and isostructural, and crystallize in the monoclinic system and C2 space group. The Pt(II) ions are coordinated by four cyanide-carbon atoms in the square-planar geometry and the [Pt(CN)4]2- ions act as a counter ion. The M(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4-aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. The crystal structures of 1 and 2 are similar each other and linked via intermolecular hydrogen bonding, Pt⋯π interactions to form 3D supramolecular network. Vibration assignments of all the observed bands are given and the spectral features also supported to the crystal structures of the complexes.

  2. Topology Synthesis of Structures Using Parameter Relaxation and Geometric Refinement

    NASA Technical Reports Server (NTRS)

    Hull, P. V.; Tinker, M. L.

    2007-01-01

    Typically, structural topology optimization problems undergo relaxation of certain design parameters to allow the existence of intermediate variable optimum topologies. Relaxation permits the use of a variety of gradient-based search techniques and has been shown to guarantee the existence of optimal solutions and eliminate mesh dependencies. This Technical Publication (TP) will demonstrate the application of relaxation to a control point discretization of the design workspace for the structural topology optimization process. The control point parameterization with subdivision has been offered as an alternative to the traditional method of discretized finite element design domain. The principle of relaxation demonstrates the increased utility of the control point parameterization. One of the significant results of the relaxation process offered in this TP is that direct manufacturability of the optimized design will be maintained without the need for designer intervention or translation. In addition, it will be shown that relaxation of certain parameters may extend the range of problems that can be addressed; e.g., in permitting limited out-of-plane motion to be included in a path generation problem.

  3. Pyro without fire: synthesis, structure, and reactivity of a dimeric vanadyl pyrophosphate coordination complex.

    PubMed

    Marino, Nadia; Hanson, Susan K; Müller, Peter; Doyle, Robert P

    2012-10-01

    The complex {[(V(IV)O)bipy(H(2)O)](2)(μ-P(2)O(7))}·3H(2)O (2) was readily obtained as a nanocrystalline powder by one-pot synthesis under mild conditions. Single crystals of 2 were grown at room temperature over 2 months, and its structure was determined. Fundamental catalytic activity was proven for this species by testing for oxidation of benzyl alcohol in air.

  4. Bis-anthracene fused porphyrins: synthesis, crystal structure, and near-IR absorption.

    PubMed

    Davis, Nicola K S; Thompson, Amber L; Anderson, Harry L

    2010-05-07

    Synthesis of fused bis-anthracene porphyrin monomers and dimers has been achieved by oxidative ring closure using FeCl(3) and Sc(OTf)(3)/DDQ, respectively. The fused compounds display red-shifted absorption spectra with maxima in the near-IR at 973 and 1495 nm, respectively, and small electrochemical HOMO-LUMO gaps. The crystal structure of the fully fused bis-anthracene porphyrin shows that it has a regular planar pi-system.

  5. Spiropyran salts and their neutral precursors: synthesis, crystal structure, photochromic transformations in solutions and solid state

    NASA Astrophysics Data System (ADS)

    Yurieva, E. A.; Aldoshin, S. M.

    2015-06-01

    This review covers investigations of spiropyran iodides with N-substituted indoline fragment, and with the pyran cycle being annelated to N-methylated pyridine ring. The schemes of synthesis of iodides and their neutral precursors, as well as results of X-ray analysis and photochemical study of the crystals of the obtained compounds are presented. Based on our and literature data, the relationship between the structure and photochromic properties has been discussed for a series of salts and neutral pyridospiropyrans.

  6. Synthesis, structures, and physical properties of aromatic molecular-bowl hydrocarbons.

    PubMed

    Wu, Yao-Ting; Siegel, Jay S

    2014-01-01

    This chapter summarizes the synthesis, physical properties, structure, and crystal packing of buckybowls. Buckybowls exemplify an intermediate class of polynuclear aromatic compounds between the closed-shell fullerenes and the flat extended arrays of graphene. These warped sheets can be seen as fragments of fullerenes or the end cap of single-walled carbon nanotubes; and, their curvature endows them with physical properties distinct from flat polynuclear hydrocarbons, which opens up unique possibilities for molecular bowls in various organic materials applications.

  7. Synthesis of highly magnetic iron nanoparticles suitable for field structuring using a β-diketone surfactant

    NASA Astrophysics Data System (ADS)

    Huber, Dale L.; Venturini, Eugene L.; Martin, James E.; Provencio, Paula P.; Patel, Rina J.

    2004-07-01

    We describe the synthesis of highly magnetic iron nanoparticles using a novel surfactant, a β-diketone. We have produced 6 nm iron nanoparticles with an unusually high saturation magnetization of more than 80% the value of bulk iron. Additionally, we measured a particle susceptibility of 14 (MKS units), which is far above the value possible for micron-scale spherical particles. These properties will allow for formation of composites that can be highly structured by magnetic fields.

  8. Studies toward the Total Synthesis of Itralamide B and Biological Evaluation of Its Structural Analogs

    PubMed Central

    Wang, Xiaoji; Lv, Chanshan; Feng, Junmin; Tang, Linjun; Wang, Zhuo; Liu, Yuqing; Meng, Yi; Ye, Tao; Xu, Zhengshuang

    2015-01-01

    Itralamides A and B were isolated from the lipophilic extract of Lyngbya majuscula collected from the eastern Caribbean. Itralamide B (1) showed cytotoxic activity towards human embryonic kidney cells (HEK293, IC50 = 6 μM). Preliminary studies disapproved the proposed stereochemistry of itralamide. In this paper, we will provide a full account of the total synthesis of four stereoisomers of itralamide B and the results derived from biological tests of these structural congeners. PMID:25871289

  9. Synthesis, structure and properties of hierarchical nanostructured porous materials studied by molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Chae, Kisung

    For applications of porous materials in many fields of technological importance, such as catalysis, filtration, separation, energy storage and conversion, the efficiency is often limited by chemical kinetics, and/or diffusion of reactants and products to and from the active sites. Hierarchical nanostructured porous materials (HNPMs) that possess both mesopores (2 nm < pore size < 50 nm) and micropores (pore size < 2 nm) have shown great potential for these applications as their bimodal porous structure can provide highly efficient mass transport through mesopores and high electrochemically accessible surface area from micropores. Despite extensive experimental studies, it remains a great challenge to quantify the synthesis-structure-properties relations in HNPMs due to the limitations of existing characterization tools and the difficulty in separating the sum of many effects in experiments. In this thesis work, we carried out a detailed study on the synthesis-structure-property relations in hierarchical nanostructured porous carbons (HNPCs) by using classical molecular dynamics (MD) simulations. We first developed a unique computational nanocasting approach in MD to mimic the synthesis of HNPCs with both mesopores from the templating and micropores from the direct quench of carbon source in MD. Mesoporous structure such as the pore size and the pore wall roughness as well as the microporous structure such as the density and the graphitic pore walls can be independently controlled by synthesis parameters, such as the size of the template, the interaction strength between the template and carbon source, the initial carbon density and the quench rate, respectively. These atomic models allowed us to quantify the structure-mechanical properties relation in aligned carbon nanotubes/amorphous porous carbon nanocomposites. Our study shows that there is an optimum balance between the crystallinity of CNTs and the number bridging bonds between CNTs and the microporous matrix

  10. Structure of a mutant form of proliferating cell nuclear antigen that blocks translesion DNA synthesis

    PubMed Central

    Freudenthal, Bret D.; Ramaswamy, S.; Hingorani, Manju M.; Washington, M. Todd

    2009-01-01

    Proliferating cell nuclear antigen (PCNA) is a homotrimeric protein that functions as a sliding clamp during DNA replication. Several mutant forms of PCNA that block translesion DNA synthesis have been identified in genetic studies in yeast. One such mutant protein (encoded by the rev6-1 allele) is a glycine to serine substitution at residue 178, located at the subunit interface of PCNA. To better understand how this substitution interferes with translesion synthesis, we have determined the X-ray crystal structure of the G178S PCNA mutant protein. This substitution has little effect on the structure of the domain in which the substitution occurs. Instead, significant, local structural changes are observed in the adjacent subunit. The most notable difference between mutant and wild-type structures is in a single, extended loop (comprising amino acid residues 105-110), which we call loop J. In the mutant protein structure, loop J adopts a very different conformation in which the atoms of the protein backbone have moved by as much as 6.5 Å from their positions in the wild-type structure. To better understand the functional consequences of this structural change, we have examined the ability of this mutant protein to stimulate nucleotide incorporation by DNA polymerase eta (pol η). Steady state kinetic studies show that while wild-type PCNA stimulates incorporation by pol η opposite an abasic site, the mutant PCNA protein actually inhibits incorporation opposite this DNA lesion. These results show that the position of loop J in PCNA plays an essential role in facilitating translesion synthesis. PMID:19053247

  11. Synthesis and applications of novel silver nanoparticle structures

    NASA Astrophysics Data System (ADS)

    Dukes, Kyle

    The field of nanotechnology is rapidly expanding across disciplines as each new development is realized. New exciting technologies are being driven by advances in the application of nanotechnology; including biochemical, optical, and semiconductors research. This thesis will focus on the use of silver nanoparticles as optical labels on cells, methods of forming different small structures of silver nanoparticles, as well as the use of silver nanoparticles in the development of a photovoltaic cell. Silver nanoparticles have been modified with self-assembled monolayers of hydroxyl-terminated long chain thiols and encapsulated with a silica shell. The resulting core-shell nanoparticles were used as optical labels for cell analysis using flow cytometry and microscopy. The excitation of plasmon resonances in nanoparticles results in strong depolarized scattering of visible light permitting detection at the single nanoparticle level. The nanoparticles were modified with neutravidin via epoxide-azide coupling chemistry and biotinylated antibodies targeting cell surface receptors were bound to the nanoparticle surface. The nanoparticle labels exhibited long-term stability under physiological conditions without aggregation or silver ion leaching. Labeled cells exhibited two orders of magnitude enhancement of the scattering intensity compared to unlabeled cells. Dimers of silver nanoparticles have been fabricated by first immobilizing a monolayer of single silver nanoparticles onto poly(4-vinylpyridine) covered glass slides. The monolayer was then exposed to adenine, which has two amines which will bind to silver. The nanoparticle monolayer, now modified with adenine, is exposed to a second suspension of nanoparticles which will bind with the amine modified monolayer. Finally, a thin silica shell is formed about the structure via solgel chemistry to prevent dissolution or aggregation upon sonication/striping. Circular arrays of silver nanoparticels are developed using a

  12. The synthesis and structural characterization of novel transition metal fluorides

    SciTech Connect

    Casteel, Jr., William Jack

    1992-09-01

    High purity KMF6 and K2MF6 salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF6. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF4 is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF4 type cell are derived from X-ray powder data for ReF4 and OsF4. Fluoride ion capture from KAgF4 provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF3 and redetermination of the AuF3 structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF3 is the mixed valence compound AgIIAg2IIIF8. Several new salts containing the (Ag - F)$n+\\atop{n}$ chain cation are prepared. The first linear (Ag - F)$n+\\atop{n}$ chain is observed in AgF+BF4- which crystallizes in a tetragonal unit. AgFAuF4 has a triclinic unit cell and is isostructural with CuFAuF4. AgFAuF6 has an orthorhombic unit cell and appears to be isostructural with AgFAsF6. A second mixed valence silver fluoride, AgIIAgIIIF5, is prepared, which magnetic measurements indicate is probably an AgF+ salt. Magnetic data for all of the AgF+ salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic AG(II) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(II) and O2 to O2+. Reactions with C6F6 and C3F6 suggest an electron capture

  13. The synthesis and structural characterization of novel transition metal fluorides

    NASA Astrophysics Data System (ADS)

    Casteel, W. J., Jr.

    1992-09-01

    High purity KMF6 and K2MF6 salts (M = Mo, Re, Ru, Os, Ir, and Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF6. Fluoride ion capture by Lewis acids from the hexafluorometallate(IV)salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF4 is determined from x-ray synchrotron and neutron powder data. Unit cells based on the orthorhombic PdF4 type cell are derived from x-ray powder data for ReF4 and OsF4. Fluoride ion capture from KAgF4 provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF3 and redetermination of the AuF3 structure from x-ray synchrotron and neutron powder data demonstrate that the two are isostructural. The thermal decomposition product of AgF3 is the mixed valence compound Ag(+2)Ag2(+3)F8. Several new salts containing the (Ag-F)n(n+) chain cation are prepared. The first linear (Ag-F)n(n+) chain is observed in AgF(+)BF4(-) which crystallizes in a tetragonal unit. AgFAuF4 has a triclinic unit cell and is isostructural with CuFAuF4. AgFAuF6 has an orthorhombic unit cell and appears to be isostructural with AgFAsF6. A second mixed valence silver fluoride, Ag(+2)Ag(+3)F5, is prepared, which magnetic measurements indicate is probably an AgF(+) salt. Magnetic data for all of the AgF(+) salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic Ag(+3) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(+2) and O2 to O2(+). Reactions with C6F and C3F6 suggest an electron capture mechanism for cationic Ag(+2) oxidations.

  14. Scar revision

    PubMed Central

    Sharma, Mohit; Wakure, Abhijeet

    2013-01-01

    Most surgical patients end up with a scar and most of these would want at least some improvement in the appearance of the scar. Using sound techniques for wound closure surgeons can, to a certain extent, prevent suboptimal scars. This article reviews the principles of prevention and treatment of suboptimal scars. Surgical techniques of scar revision, i.e., Z plasty, W plasty, and geometrical broken line closure are described. Post-operative care and other adjuvant therapies of scars are described. A short description of dermabrasion and lasers for management of scars is given. It is hoped that this review helps the surgeon to formulate a comprehensive plan for management of scars of these patients. PMID:24516292

  15. Knowledge-Directed Theory Revision

    NASA Astrophysics Data System (ADS)

    Ali, Kamal; Leung, Kevin; Konik, Tolga; Choi, Dongkyu; Shapiro, Dan

    Using domain knowledge to speed up learning is widely accepted but theory revision of such knowledge continues to use general syntactic operators. Using such operators for theory revision of teleoreactive logic programs is especially expensive in which proof of a top-level goal involves playing a game. In such contexts, one should have the option to complement general theory revision with domain-specific knowledge. Using American football as an example, we use Icarus' multi-agent teleoreactive logic programming ability to encode a coach agent whose concepts correspond to faults recognized in execution of the play and whose skills correspond to making repairs in the goals of the player agents. Our results show effective learning using as few as twenty examples. We also show that structural changes made by such revision can produce performance gains that cannot be matched by doing only numeric optimization.

  16. Synthesis, characterization and structural aspects of 3-azidopropylsilatrane

    NASA Astrophysics Data System (ADS)

    Singh, Raghubir; Kishore Puri, Jugal; Pal Sharma, Raj; Kumar Malik, Ashok; Ferretti, Valeria

    2010-10-01

    Reaction of 3-chloropropyltriethoxysilane ( 1) with sodium azide ( 2) in the presence of phase transfer catalyst, tert-butylammonium bromide provided 3-azidopropyltriethoxysilane ( 3). This undergoes transesterification reaction with triethanolamine in the presence of KOH to form a new silatrane 3-azidopropylsilatrane ( 4). Multinuclear NMR ( 1H, 13C and 29Si), IR and elemental analyses support the structure of novel silatrane 4. 29Si NMR indicates the presence of penta-coordinated silicon atom, which is supported by X-ray studies. It revealed that Si is present in distorted trigonal bipyramidal environment with three O atoms in equatorial positions and N atom at one of the apical positions. The second axial position is occupied by long alkyl chain bearing azide moiety. The interaction of Si with N forms a transannular bond having 2.176 Å bond length.

  17. Ion Beam Synthesis Of Metal - Silicon Carbide - Si Multilayer Structures

    NASA Astrophysics Data System (ADS)

    Lindner, J. K. N.; Tsang, W. M.; Stritzker, B.; Wong, S. P.

    2003-08-01

    High doses of Ti, Ni, Mo, or W ions were implanted at elevated temperatures either conventionally or using a MEVVA ion source into ion beam synthesized Si/SiC/Si or SiC/Si layer structures in order to create metallic layers contacting the SiC. The depth distribution of metal atoms and the formation of silicide and carbide phases as well as the formation of cavities at the lower SiC/Si interface are studied by Rutherford backscattering spectroscopy (RBS) and cross-sectional transmission electron microscopy (XTEM). A brief survey of the effects ocurring in the ion beam metallization of SiC films is given and the benefit of using ion beams for metallization of thin films is elucidated.

  18. Stochastic Control Synthesis of Systems with Structured Uncertainty

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L. (Technical Monitor); Crespo, Luis G.

    2003-01-01

    This paper presents a study on the design of robust controllers by using random variables to model structured uncertainty for both SISO and MIMO feedback systems. Once the parameter uncertainty is prescribed with probability density functions, its effects are propagated through the analysis leading to stochastic metrics for the system's output. Control designs that aim for satisfactory performances while guaranteeing robust closed loop stability are attained by solving constrained non-linear optimization problems in the frequency domain. This approach permits not only to quantify the probability of having unstable and unfavorable responses for a particular control design but also to search for controls while favoring the values of the parameters with higher chance of occurrence. In this manner, robust optimality is achieved while the characteristic conservatism of conventional robust control methods is eliminated. Examples that admit closed form expressions for the probabilistic metrics of the output are used to elucidate the nature of the problem at hand and validate the proposed formulations.

  19. Synthesis, structure and physical properties of a low dimensional compound

    NASA Astrophysics Data System (ADS)

    Ramos Silva, Manuela; Coutinho, Joana T.; Pereira, Laura C. J.; Martín-Ramos, Pablo; Waerenborgh, João C.

    2017-02-01

    The crystal structure of (μ3-oxo)hexakis(cyanoacetato-κO,O‧)(cyanoacetato-κO)diaquatriiron(III) cyanoacetic acid shows the formation of trinuclear complexes in a hydrogen-bond network that bonds all the molecules in a 3D arrangement. For this complex, within whose clusters the whole magnetic interaction takes place, 57Fe Mössbauer spectroscopy shows that the Fe cations are in the S = 5/2 state in the temperature range 2-295 K. The asymmetric broadening of the absorption peaks below 80 K is consistent with strong antiferromagnetic interactions between the metal spins. The magnetization measurements also show the antiferromagnetic character of the spin ensemble and an ST = 1/2 magnetic ground state typical of triangular systems with similar J between Fe-Fe pairs.

  20. Synthesis, structure and dynamics of NHC-based palladium macrocycles.

    PubMed

    Andrew, Rhiann E; Chaplin, Adrian B

    2014-01-21

    A series of macrocyclic CNC pincer pro-ligands based on bis(imidazolium)lutidine salts with octa-, deca- and dodecamethylene spacers have been prepared and their coordination chemistry investigated. Using a Ag2O based transmetallation strategy, cationic palladium(II) chloride complexes [PdCl{CNC-(CH2)n}][BAr(F)4] (n = 8, 10, 12; Ar(F) = 3,5-C6H3(CF3)2) were prepared and fully characterised in solution, by NMR spectroscopy and ESI-MS, and in the solid-state, by X-ray crystallography. The smaller macrocyclic complexes (n = 8 and 10) exhibit dynamic behaviour in solution, involving ring flipping of the alkyl spacer across the Pd-Cl bond, which was interrogated by variable temperature NMR spectroscopy. In the solid-state, distorted coordination geometries are observed with the spacer skewed to one side of the Pd-Cl bond. In contrast, a static C2 symmetric structure is observed for the dodecamethylene based macrocycle. For comparison, palladium(II) fluoride analogues [PdF{CNC-(CH2)n}][BAr(F)4] (n = 8, 10, 12) were also prepared and their solution and solid-state structures contrasted with those of the chlorides. Notably, these complexes exhibit very low frequency (19)F chemical shifts (ca. -400 ppm) and the presence of C-H···F interactions ((2h)J(FC) coupling observed by (13)C NMR spectroscopy). The dynamic behaviour of the fluoride complexes is largely consistent with the smaller ancillary ligand; [PdF{CNC-(CH2)8}][BAr(F)4] exceptionally shows C(2v) time averaged symmetry in solution at room temperature (CD2Cl2, 500 MHz) as a consequence of dual fluxional processes of the pincer backbone and alkyl spacer.

  1. Synthesis, structure and physical properties of selected transition metal oxides

    NASA Astrophysics Data System (ADS)

    Waldron, Joanna Elizabeth Leah

    Monoclinic Nb12O29 has been synthesised by topotactic reduction of H-Nb2O5. It has a complex crystallographic shear structure made up of 3x4 blocks of corner shared NbO6 octahedra. Nb12O29 is mixed d0/d1 compound which, can be written as Nb4+2NB5+10O29. It has been found, using Rietveld refinement of powder neutron diffraction data, to undergo a charge ordering transition at around 12K resulting in a lowering of symmetry from A2/m to Am. Below this transition, one Nb4+ ion is localised on a crystallographically distinct site in the centre of the 3x4 blocks. This charge ordering transition has an associated transition to an incommensurate one dimensional antiferromagnetic state. The nature of the magnetic order has been investigated using susceptibility and SR measurements. Susceptibility measurements reveal that only 48% of the Nb4+ in the system is localised, and its temperature dependence is well fitted to a Bonner-Fisher model for S=1/2 one dimensional antiferromagnets. It is found that the remaining valence electrons in NB12O29 itinerant and contribute to its metallic conductivity. Further evidence for the unique properties of monoclinic Nb12O29 has been obtained by doping the structure with small amounts of diamagnetic Ti4+, which rapidly causes a destruction of the long range magnetic order at only 3% doping, but leaves the metallic conductivity unaffected, as is expected for a one dimensional chain.

  2. Synthesis of (−)‐Cannabimovone and Structural Reassignment of Anhydrocannabimovone through Gold(I)‐Catalyzed Cycloisomerization

    PubMed Central

    Carreras, Javier; Kirillova, Mariia S.

    2016-01-01

    Abstract The first total synthesis of cannabimovone from Cannabis sativa and anhydrocannabimovone was achieved by means of a highly stereoselective gold(I)‐catalyzed cycloisomerization. The results led to reassignment of the structure of anhydrocannabimovone. PMID:27119910

  3. Ordovician and Silurian Phi Kappa and Trail Creek formations, Pioneer Mountains, central Idaho; stratigraphic and structural revisions, and new data on graptolite faunas

    USGS Publications Warehouse

    Dover, James H.; Berry, William B.N.; Ross, Reuben James

    1980-01-01

    Recent geologic mapping in the northern Pioneer Mountains combined with the identification of graptolites from 116 new collections indicate that the Ordovician and Silurian Phi Kappa and Trail Creek Formations occur in a series of thrust-bounded slices within a broad zone of imbricate thrust faulting. Though confirming a deformational style first reported in a 1963 study by Michael Churkin, our data suggest that the complexity and regional extent of the thrust zone were not previously recognized. Most previously published sections of the Phi Kappa and Trail Creek Formations were measured across unrecognized thrust faults and therefore include not only structural repetitions of graptolitic Ordovician and Silurian rocks but also other tectonically juxtaposed lithostratigraphic units of diverse ages as well. Because of this discovery, the need to reconsider the stratigraphic validity of these formations and their lithology, nomenclature, structural distribution, facies relations, and graptolite faunas has arisen. The Phi Kappa Formation in most thrust slices has internal stratigraphic continuity despite the intensity of deformation to which it was subjected. As revised herein, the Phi Kappa Formation is restricted to a structurally repeated succession of predominantly black, carbonaceous, graptolitic argillite and shale. Some limy, light-gray-weathering shale occurs in the middle part of the section, and fine-grained locally pebbly quartzite is present at the base. The basal quartzite is here named the Basin Gulch Quartzite Member of the Phi Kappa. The Phi Kappa redefined on a lithologic basis represents the span of Ordovician time from W. B. N. Berry's graptolite zones 2-4 through 15 and also includes approximately 17 m of lithologically identical shale of Early and Middle Silurian age at the top. The lower contact of the formation as revised is tectonic. The Phi Kappa is gradationally overlain by the Trail Creek Formation as restricted herein. Most of the coarser

  4. Synthesis of Specifically Modified Oligonucleotides for Application in Structural and Functional Analysis of RNA

    PubMed Central

    Rublack, Nico; Nguyen, Hien; Appel, Bettina; Springstubbe, Danilo; Strohbach, Denise; Müller, Sabine

    2011-01-01

    Nowadays, RNA synthesis has become an essential tool not only in the field of molecular biology and medicine, but also in areas like molecular diagnostics and material sciences. Beyond synthetic RNAs for antisense, aptamer, ribozyme, and siRNA technologies, oligoribonucleotides carrying site-specific modifications for structure and function studies are needed. This often requires labeling of the RNA with a suitable spectroscopic reporter group. Herein, we describe the synthesis of functionalized monomer building blocks that upon incorporation in RNA allow for selective reaction with a specific reporter or functional entity. In particular, we report on the synthesis of 5′-O-dimethoxytrityl-2′-O-tert-butyldimethylsilyl protected 3′-O-phosphoramidites of nucleosides that carry amino linkers of different lengths and flexibility at the heterocyclic base, their incorporation in a variety of RNAs, and postsynthetic conjugation with fluorescent dyes and nitroxide spin labels. Further, we show the synthesis of a flavine mononucleotide-N-hydroxy-succinimidyl ester and its conjugation to amino functionalized RNA. PMID:22013508

  5. Hydrothermal synthesis of zeolites with three dimensionally ordered mesoporous-imprinted (3DOm-i) structure

    SciTech Connect

    Chen, Huiyong; Wydra, James; Zhang, Xueyi; Lee, Pyung-Soo; Wang, Zhuopeng; Fan, Wei; Tsapatsis, Michael

    2011-08-17

    Zeolites are microporous materials with pores and channels of molecular dimensions that find numerous applications in catalysis, separations, ion exchange, etc. However, whereas uniformity of micropore size is a most desirable and enabling characteristic for many of their uses, in certain cases, for example in reactions involving bulky molecules, it is a limitation. For this reason, synthesis of hierarchical zeolites with micro- and mesoporosity is of considerable interest as a way to control molecular traffic for improved catalytic and separation performance. Herein, we report a general synthesis route for the confined synthesis of zeolites within three-dimensionally ordered mesoporous carbon templates by conventional hydrothermal synthesis. Various zeolites, including BEA, LTA, FAU, and LTL, with three-dimensionally ordered mesoporous-imprinted structure have been synthesized by this approach. It is expected that these hierarchical zeolite materials will provide building blocks for thin-film and other syntheses and may provide a basis for quantitatively studying the mass-transfer limitation on the catalytic performance of zeolite catalysts.

  6. Hydrothermal synthesis of zeolites with three-dimensionally ordered mesoporous-imprinted structure.

    PubMed

    Chen, Huiyong; Wydra, James; Zhang, Xueyi; Lee, Pyung-Soo; Wang, Zhuopeng; Fan, Wei; Tsapatsis, Michael

    2011-08-17

    Zeolites are microporous materials with pores and channels of molecular dimensions that find numerous applications in catalysis, separations, ion exchange, etc. However, whereas uniformity of micropore size is a most desirable and enabling characteristic for many of their uses, in certain cases, for example in reactions involving bulky molecules, it is a limitation. For this reason, synthesis of hierarchical zeolites with micro- and mesoporosity is of considerable interest as a way to control molecular traffic for improved catalytic and separation performance. Herein, we report a general synthesis route for the confined synthesis of zeolites within three-dimensionally ordered mesoporous carbon templates by conventional hydrothermal synthesis. Various zeolites, including BEA, LTA, FAU, and LTL, with three-dimensionally ordered mesoporous-imprinted structure have been synthesized by this approach. It is expected that these hierarchical zeolite materials will provide building blocks for thin-film and other syntheses and may provide a basis for quantitatively studying the mass-transfer limitation on the catalytic performance of zeolite catalysts.

  7. Seismic structure of the northwestern Japan convergent margin: A synthesis

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Horiuchi, Shigeki; Umino, Norihito

    1994-11-01

    Many studies recently made on the basis of seismic observations have revealed a detailed structure of the crust and the upper mantle beneath the northeastern Japan arc and its relationship to seismic and volcanic activity. Spatial distributions of the depths to the Conrad and the Moho discontinuities, estimated from shallow earthquake data and seismic explosion data, show that both discontinuities are deep in the middle of the land area and shallow toward the coastlines of the Japan Sea and the Pacific Ocean. The Pn velocity has a lateral variation; it is as low as approximately 7.5 km/s beneath the land area, while that beneath the Japan Sea and the Pacific Ocean is 8.0-8.2 km/s. It changes abruptly at the transition zones, which are located along the coastlines. Precise structure and location of the subducted Pacific plate beneath the land area is inferred from converted or reflected seismic waves at the top or bottom of the plate. The Pacific plate is composed of a thin (approximately 5 km) low-velocity upper layer and a thick high-velocity lower layer, its total thickness being 80-90 km. The upper plane seismicity of the double seismic zone is confined to the thin low-velocity upper layer, which probably corresponds to the subducted former oceanic crust. The lower plane seismicity lies at the middle of the high-velocity lower layer, and the lower half of the plate below it is incapable of generating earthquakes. The shallower portion of the upper surface of the plate beneath the Pacific Ocean, along which major seismicity with low-angle thrust faultings is actually occurring, is also located by seismic observations on land and in the sea. The Pacific plate subducts at an extremely low angle of approximately 5 deg for the first approximately 25-km depth, and then the dip steepens rather abruptly to approximately 30 deg. Normal-fault type events at the top of the plate have not been detected in the portion where the downward-bending is the largest, but have been

  8. Pentanuclear Lanthanide Mono-organophosphates: Synthesis, Structure, and Magnetism.

    PubMed

    Gupta, Sandeep K; Langley, Stuart K; Sharma, Kamna; Murray, Keith S; Murugavel, Ramaswamy

    2017-04-03

    Research on rare-earth phosphates has recently received substantial interest because of their unique physical and chemical properties. In recent years, because of their low solubility, research interest has been built on developing methodologies to prepare nanostructures and grow single crystals of inorganic rare-earth phosphates. The chemistry of rare-earth organophosphates, however, is still at a latent stage. Contrary to the traditional hydrothermal route, we report rare examples of discrete pentanuclear lanthanide(III) organophosphate clusters assembled from a sterically encumbered monoester of phosphoric acid under mild reaction conditions. Single-crystal X-ray analysis revealed that all of the compounds possess a similar core structure, [Ln5(μ3-OH)(dipp)6(NO3)x(CH3OH)y(H2O)z](2+) [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9); dipp = 2,6-diisopropylphenylphosphate], where the anionic charge balance is maintained by the presence of chelating nitrate anions (in the case of 9, x = 0), protonated tmeda, or dipp(2-) ligands. The vacant coordination sites on the metal ions are satisfied by coordinated methanol or water molecules. The core structure of these clusters is built on a [Ln3(μ3-OH)(dipp)6] triangle where the phosphate ligands bridge to two further Ln(III) ions. The complexes display lanthanide contraction along the series, with Ln(III) ions displaying different coordination environments/geometries as we move along the series. All of the compounds have been characterized by both analytical and spectroscopic techniques. Magnetic studies revealed the presence of weak antiferromagnetic exchange through the bridging μ3-hydroxo moiety and organophosphate groups for the {Gd(III)5} analogue, with a significant magnetic entropy change (25.8 J kg(-1) K(-1), ΔH = 7 T). The anisotropic complexes reveal an absence of slow relaxation of magnetization, except for Nd (1), Dy (6), and Er (8), which show slow relaxation in an applied DC

  9. Synthesis and structural comparison of triaryl(sulfonylimino)pnictoranes.

    PubMed

    Matano, Yoshihiro; Nomura, Hazumi; Suzuki, Hitomi

    2002-04-08

    Triarylphosphanes 1 (Ar(3)P; Ar = Ph, 4-MeC(6)H(4)), triphenylarsane (2), and triarylstibanes 3 (Ar(3)Sb; Ar = 2-MeC(6)H(4), 2-MeOC(6)H(4)) reacted with trifluoromethanesulfonamide (7a) in the presence of equimolar diethyl azodicarboxylate to afford the corresponding triaryl(sulfonylimino)pnictoranes [Ar(3)M=NSO(2)CF(3); 8 (M = P), 9 (M = As), 10 (M = Sb)]. The Kirsanov-type reaction of triarylantimony dichlorides 5 (Ar(3)SbCl(2); Ar = 2-MeC(6)H(4), 2-MeOC(6)H(4)) and triarylbismuth dichlorides 6 (Ar(3)BiCl(2); Ar = 2-MeC(6)H(4), 2-MeOC(6)H(4), 2,4,6-Me(3)C(6)H(2)) with sulfonamides 7 (H(2)NSO(2)R; R = CF(3), 4-MeC(6)H(4), Me) in the presence of 2 equiv of potassium tert-butoxide yielded triaryl(sulfonylimino)-lambda(5)-stibanes 10 and -bismuthanes 11, respectively. The ortho-substitution in aryl ligands of 10 and 11 has been found to bring about considerable kinetic stabilization of the reactive Sb=N and Bi=N bonds. A structural comparison was made for a series of triaryl(sulfonylimino)pnictoranes 8-11 by IR spectroscopy and X-ray crystallography. In the IR spectra of 9-11, SO(2) asymmetric stretching absorptions (nu(SO2)) were observed at lower wavenumbers as compared to those of phosphorus counterparts 8. The difference in frequency (Deltanu(SO2)) from 8 increased progressively as the pnictogen element being utilized moved down the group 15 column on the periodic table. X-ray crystallographic analyses of eight of the triaryl(sulfonylimino)pnictoranes prepared confirmed the increasing single-bond character of the M=N bond, with the contribution from the canonical structure M(+)-N=S(O)-O(-) increasing in importance in the order P < As < Sb < Bi. Among all triaryl(sulfonylimino)pnictoranes examined, only imino-lambda(5)-bismuthanes 11 oxidized alcohols to carbonyl compounds.

  10. Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties.

    PubMed

    Rausch, Janek; Lorenz, Volker; Hrib, Cristian G; Frettlöh, Vanessa; Adlung, Matthias; Wickleder, Claudia; Hilfert, Liane; Jones, Peter G; Edelmann, Frank T

    2014-11-03

    This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect.

  11. Synthesis, Structure and Properties of BN Nanotubes, BN/SiC and CBN/SiC Micro/Nano-Whiskers

    DTIC Science & Technology

    2003-12-01

    Synthesis, Structure and Properties of BN Nanotubes, BN/SiC and CBN/SiC Micro / Nano -Whiskers 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5d...Synthesis, Structure and Properties of BN Nanotubes, BN/SiC and CBN/SiC Micro / Nano -Whiskers CRDF COOPERATIVE GRANTS PROGRAM: FINAL PROJECT...SiC and CBN/SiC micro - nano -whiskers. In the result variety of BN nanostructures have been synthesized by carbothermal technique and characterized

  12. Two‐Dimensional Fluorinated Graphene: Synthesis, Structures, Properties and Applications

    PubMed Central

    Long, Peng; Feng, Yiyu; Li, Yu

    2016-01-01

    Fluorinated graphene, an up‐rising member of the graphene family, combines a two‐dimensional layer‐structure, a wide bandgap, and high stability and attracts significant attention because of its unique nanostructure and carbon–fluorine bonds. Here, we give an extensive review of recent progress on synthetic methods and C–F bonding; additionally, we present the optical, electrical and electronic properties of fluorinated graphene and its electrochemical/biological applications. Fluorinated graphene exhibits various types of C–F bonds (covalent, semi‐ionic, and ionic bonds), tunable F/C ratios, and different configurations controlled by synthetic methods including direct fluorination and exfoliation methods. The relationship between the types/amounts of C–F bonds and specific properties, such as opened bandgap, high thermal and chemical stability, dispersibility, semiconducting/insulating nature, magnetic, self‐lubricating and mechanical properties and thermal conductivity, is discussed comprehensively. By optimizing the C–F bonding character and F/C ratios, fluorinated graphene can be utilized for energy conversion and storage devices, bioapplications, electrochemical sensors and amphiphobicity. Based on current progress, we propose potential problems of fluorinated graphene as well as the future challenge on the synthetic methods and C‐F bonding character. This review will provide guidance for controlling C–F bonds, developing fluorine‐related effects and promoting the application of fluorinated graphene. PMID:27981018

  13. Synthesis, structural characterisation and biological evolution of chromanones

    NASA Astrophysics Data System (ADS)

    Mayuri, Bheemarasetti; Kavitha, P.; Basavoju, Srinivas; Bhargavi, G.; Reddy, K. Laxma

    2017-10-01

    Four new chromanone derivatives (4a-d) are synthesized and evaluated for their DNA binding, cleavage and antioxidant activities. The synthesized compounds are characterized by Fourier Transform Infrared (FTIR), 1H and 13C nuclear magnetic resonance (NMR), mass spectrometry, UV-Visible, thermal and fluorescence spectral studies. Finally, structures of the compounds 4a and 4b are confirmed by single crystal X-ray diffraction method. The DNA binding study is carried out by electronic absorption spectroscopy and fluorescence spectroscopy. The observation from the results is that the chromanone derivatives 4a-d binds to CT-DNA in an intercalation mode. The DNA cleavage studies are investigated using supercoiled pET28a plasmid DNA by agarose gel electrophoresis. These studies reveal that the compounds act as efficient cleaving agents even in the absence of an oxidative agent H2O2. The antioxidant studies of these compounds in vitro are evaluated and compared with that of standard drug ascorbic acid (AA).

  14. Synthesis and textural evolution of alumina particles with mesoporous structures

    SciTech Connect

    Liu Xun; Peng Tianyou; Yao Jinchun; Lv Hongjin; Huang Cheng

    2010-06-15

    Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous {gamma}-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl{sup -} in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into {gamma}-Al{sub 2}O{sub 3} particles with mesostructures after further calcination at 1173 K, whereas coexisting SO{sub 4}{sup 2-} can promote above morphology evolution and then transformed into {gamma}-Al{sub 2}O{sub 3} nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m{sup 2} g{sup -1} even after calcinations at 1173 K. - Graphical abstract: Co-existing Cl{sup -} is beneficial for the formation of {gamma}-alumina nanoparticles with mesostructures during the precipitation process. Interparticle and intraparticle mesopores can be derived from acidic solution and near neutral solution, respectively.

  15. Crystal structure controlled synthesis and characterization of copper sulfide nanoparticles

    SciTech Connect

    Senthilkumar, M.; Babu, S. Moorthy

    2016-05-23

    Phase pure, controlled crystal structure of digenite (Cu{sub 9}S{sub 5}) copper sulfide nanoparticles were synthesized by hot injection method at the temperature of 180°C. The mixture of Oleylamine, 1-Octadecene and 1-Dodecanethiol were taken as solvent as well as capping agents. The effect of the mixture of solvents on the phase formation and morphology of the synthesized nanoparticles were analysed. The nanocrystals were characterized using X-Ray diffraction (XRD) which confirms the presence of single phase rhombohedral digenite Cu{sub 9}S{sub 5} NPs, Morphological analysis clearly depicts the formation of hexagonal faceted Cu{sub 9}S{sub 5} NPs, Energy dispersive X-ray absorption spectroscopy (EDS) reveals the stoichiometric ratio of 1.8:1 for synthesized NPs. From the UV-Vis absorption spectroscopy the bandgap value of Cu{sub 1.8}S is found to be 1.71 eV. The presence of capping agents along the surface of the Cu{sub 9}S{sub 5} NPs was confirmed from FTIR analysis.

  16. Two-Dimensional Fluorinated Graphene: Synthesis, Structures, Properties and Applications.

    PubMed

    Feng, Wei; Long, Peng; Feng, Yiyu; Li, Yu

    2016-07-01

    Fluorinated graphene, an up-rising member of the graphene family, combines a two-dimensional layer-structure, a wide bandgap, and high stability and attracts significant attention because of its unique nanostructure and carbon-fluorine bonds. Here, we give an extensive review of recent progress on synthetic methods and C-F bonding; additionally, we present the optical, electrical and electronic properties of fluorinated graphene and its electrochemical/biological applications. Fluorinated graphene exhibits various types of C-F bonds (covalent, semi-ionic, and ionic bonds), tunable F/C ratios, and different configurations controlled by synthetic methods including direct fluorination and exfoliation methods. The relationship between the types/amounts of C-F bonds and specific properties, such as opened bandgap, high thermal and chemical stability, dispersibility, semiconducting/insulating nature, magnetic, self-lubricating and mechanical properties and thermal conductivity, is discussed comprehensively. By optimizing the C-F bonding character and F/C ratios, fluorinated graphene can be utilized for energy conversion and storage devices, bioapplications, electrochemical sensors and amphiphobicity. Based on current progress, we propose potential problems of fluorinated graphene as well as the future challenge on the synthetic methods and C-F bonding character. This review will provide guidance for controlling C-F bonds, developing fluorine-related effects and promoting the application of fluorinated graphene.

  17. Phosphine derivatives of sparfloxacin - Synthesis, structures and in vitro activity

    NASA Astrophysics Data System (ADS)

    Komarnicka, Urszula K.; Starosta, Radosław; Guz-Regner, Katarzyna; Bugla-Płoskońska, Gabriela; Kyzioł, Agnieszka; Jeżowska-Bojczuk, Małgorzata

    2015-09-01

    We synthesized two derivatives of sparfloxacin (HSf): aminomethyl(diphenyl)phosphine (PSf) and its oxide (OPSf). The compounds were characterized by NMR spectroscopy, MS and elemental analysis. In addition, the molecular structures of the compounds were determined using DFT and X-ray (OPSf) analysis. The antibacterial activity of HSf and both derivatives was tested against four reference and fifteen clinical Gram-positive and Gram-negative strains of bacteria (sensitive or resistant to fluoroquinolones). The results showed that the activity of PSf was similar to or higher than the activity of HSf, while OPSf was found significantly less active. The compounds were also tested in vitro toward the following cancer cell lines: mouse colon carcinoma (CT26) and human lung adenocarcinoma (A549). Regardless of the cancer cell line, derivatization of HSf resulted in the gradual increase of cytotoxicity. OPSf exhibited the highest one (4 h - incubation time: IC50(CT26) = 51.0 ± 1.2; IC50(A549) = 74.9 ± 1.4 and 24 h: IC50(CT26) = 109.2 ± 8.8; IC50(A549) = 52.7 ± 9.2).

  18. Pyridylphosphinate metal complexes: synthesis, structural characterisation and biological activity.

    PubMed

    Cross, Jasmine M; Gallagher, Natalie; Gill, Jason H; Jain, Mohit; McNeillis, Archibald W; Rockley, Kimberly L; Tscherny, Fiona H; Wirszycz, Natasha J; Yufit, Dmitry S; Walton, James W

    2016-08-09

    For the first time, a series of 25 pseudo-octahedral pyridylphosphinate metal complexes (Ru, Os, Rh, Ir) has been synthesised and assessed in biological systems. Each metal complex incorporates a pyridylphosphinate ligand, a monodentate halide and a capping η(6)-bound aromatic ligand. Solid- and solution-state analyses of two complexes reveal a structural preference for one of a possible two diastereomers. The metal chlorides hydrolyse rapidly in D2O to form a 1 : 1 equilibrium ratio between the aqua and chloride adducts. The pKa of the aqua adduct depends upon the pyridyl substituent and the metal but has little dependence upon the phosphinate R' group. Toxicity was measured in vitro against non-small cell lung carcinoma H460 cells, with the most potent complexes reporting IC50 values around 50 μM. Binding studies with selected amino acids and nucleobases provide a rationale for the variation in toxicity observed within the series. Finally, an investigation into the ability of the chelating amino acid l-His to displace the phosphinate O-metal bond shows the potential for phosphinate complexes to act as prodrugs that can be activated in the intracellular environment.

  19. Synthesis and structural analysis of some trinitromethanide salts

    NASA Astrophysics Data System (ADS)

    Gakh, A. A.; Bryan, J. C.; Burnett, M. N.; Bonnesen, P. V.

    2000-03-01

    Two trinitromethanide (TNM) salts containing weakly coordinating cations (tetrabutylammonium and cesium) were synthesized via incomplete nitration of acetic anhydride followed by cation exchange with tetrabutylammonium bromide and cesium fluoride. Their structural characteristics were determined by single crystal X-ray crystallography [J.C. Bryan, M.N. Burnett, A.A. Gakh, Acta Crystallogr., Sect. C (Cr. Str. Comm.) 54 (1998) 1229] followed by comparative analysis with the literature data. In all cases, the TNM anion was found to be a non-planar system. The sum of dihedral angles between the central (C-N 3) plane of the anion and the planes of the individual nitro groups varies from 60 to 100°. C-N and N-O interatomic distances in TNM anion can be correlated with the dihedral angles of the corresponding nitro groups. The 13C and 14N NMR spectra of the TNM anion are very simple (broad singlets), an indication of the equivalence (on the NMR time scale) of the nitro groups in solution. The distribution ratio between organic phase (tributyl phosphate) and water is 5000 times higher for Cs +C(NO 2) 3- compared to Cs +NO 3-, presumably due to size and/or charge delocalization differences between nitrate and TNM anions.

  20. Synthesis, structural and fungicidal studies of hydrazone based coordination compounds

    NASA Astrophysics Data System (ADS)

    Sharma, Amit Kumar; Chandra, Sulekh

    2013-02-01

    The coordination compounds of the Co(II), Ni(II) and Cu(II) metal ions derived from imine based ligand, benzil bis(carbohydarzone) were structurally and pharmaceutically studied. The compounds have the general stoichiometry [M(L)]X2 and [Co(L)X2], where M = Ni(II) and Cu(II), and X=NO3- and Cl- ions. The analytical techniques like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV/Visible, NMR, ESI mass and EPR were used to study the compounds. The key IR bands, i.e., amide I, amide II and amide III stretching vibrations accounts for the tetradentate metal binding nature of the ligand. The electronic and EPR spectral results suggest the square planar Ni(II) and Cu(II) complexes (giso = 2.11-2.22) and tetragonal geometry Co(II) complexes (giso = 2.10-2.17). To explore the compounds in the biological field, they were examined against the opportunistic pathogens, i.e., Alternaria brassicae, Aspergillus niger and Fusarium oxysporum. The partial covalent character of metal-ligand bond is supported by the orbital reduction factor k (0.62-0.92) and nephalauxetic parameter β (0.55-0.57).

  1. Synthesis and structure-activity relationships of skin ceramides.

    PubMed

    Novotný, J; Hrabálek, A; Vávrová, K

    2010-01-01

    Ceramides are a complex group of lipids that has gained much attention as cell signaling molecules and skin barrier constituents. In the skin, these sphingolipids form a major part of the stratum corneum intercellular lipid matrix, which is the barrier for penetration of most compounds. The development of such a protective layer was a critical step in the evolution of life on a dry land. Moreover, prominent skin diseases such as psoriasis and atopic dermatitis are associated with diminished ceramide levels and may be effectively improved by exogenous ceramides or their analogues. Since ceramides are not obtained from natural sources in pure form, they are of synthetic interest since 1950's. In this review, we describe sphingosine syntheses from 1998 until 2008, and the synthetic approaches to the unique epidermal ceramides, including the 6-hydroxysphingosine-based ones, the alpha- and omega-hydroxy forms and the omega-acyloxy species. Moreover, the structural requirements of ceramides for a competent skin barrier are discussed, including acyl chain length, trans double bond, acyl alpha-hydroxyl, stereochemistry, omega-linoleyloxy species and ceramide conformation.

  2. Synthesis, structural, catecholase, tyrosinase and DFT studies of pyrazoloquinoxaline derivatives

    NASA Astrophysics Data System (ADS)

    Bouanane, Zohra; Bounekhel, Mahmoud; Elkolli, Meriem; Abrigach, Farid; Khoutoul, Mohamed; Bouyala, Rabab; Touzani, Rachid; Hellal, Abdelkader

    2017-07-01

    Six functional multidentate ligands: 2,3-bis(3,5-dimethyl-1H-pyrazol-1-yl) quinoxaline, L1, 2,3-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-nitroquinoxaline, L2, 2,3-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methylquinoxaline, L3, 2-(3,5-dimethyl-1H-pyrazol-1-yl)-3-hydrazinyl-6-nitroquinoxaline L4, 2-chloro-3-(3,5-dimethyl-1H-pyrazol-1-yl)-6-methylquinoxaline, L5, 2-chloro-3-(3,5-dimethyl-1H-pyrazol-1-yl) quinoxaline, L6, and a new copper (II) complex, were prepared and evaluated for their catecholase activities at aerobic conditions. We found that, the reaction rate depends on: The nature of the substituents in the quinoxaline ring, counter anion, metal, concentration of ligand and the used solvent. The complex obtained in-situ from reaction of one equivalent of ligand L1 and two equivalents of Cu(CH3COO)2 in methanol showed the highest oxidation rate activity (V = 33.48 μmol L-1. min-1). In addition, geometry optimizations of the complexes in order to get better insight into the geometry and the electronic structure and chemical reactivity were carried out by means of DFT calculations.

  3. Synthesis and structures of cationic aluminum and galllium amidinate complexes

    SciTech Connect

    Dagorne, S.; Guzei, I.A.; Coles, M.P.; Jordan, R.F.

    2000-01-19

    Aluminum and gallium amidinate complexes, {l{underscore}brace}RC(NR{prime}){sub 2}{r{underscore}brace}MMe{sub 2} (R, R{prime} = alkyl; M - Al, Ga), react with the ``cationic activators'' [Ph{sub 3}C][B(C{sub 6}F{sub 5}){sub 4}] and B(C{sub 6}F{sub 5}){sub 3} to yield cationic Al and Ga alkyl species whose structures are strongly influenced by the steric properties of the amidinate ligand. The reaction of acetamidinate Al complexes {l{underscore}brace}MeC(NR{prime}){sub 2}{r{underscore}brace}AlMe{sub 2}(R{prime} = {sup i}Pr, 1a; R{prime} = Cy, 3a) with 0.5 equiv of [Ph{sub 3}C][B(C{sub 6}F{sub 5}){sub 4}] or B(C{sub 6}F{sub 5}){sub 3} yields {l{underscore}brace}MeC(NR{prime}){sub 2}{r{underscore}brace}{sub 2}Al{sub 2}Me{sub 3}{sup +} (R{prime} - {sup i}Pr, 2a{sup +}; R{prime} = Cy, 4a{sup +}) as the B(C{sub 6}F{sub 5}){sub 4}{sup {minus}} or MeB(C{sub 6}F{sub 5}){sub 3}{sup {minus}} salts. X-ray crystallographic analyses establish that 2a{sup +} and 4a{sup +} are double-amidinate-bridged dinuclear cations, in which the two metal centers are linked by {mu}-{eta}{sup 1},{eta}{sup 1} and {mu}-{eta}{sup 1},{eta}{sup 2} amidinate bridges. NMR studies show that 2a{sup +} undergoes two dynamic processes in solution: (1) a {mu}-{eta}{sup 1},{eta}{sup 1}/{mu}-{eta}{sup 1},{eta}{sup 2} amidinate exchange and (2) Me exchange between the two metal centers. The reaction of {l{underscore}brace}MeC(N{sup i}Pr){sub 2}{r{underscore}brace} (1b) with 0.5 equiv of B(C{sub 6}F{sub 5}){sub 3} yields {l{underscore}brace}MeC(N{sup i}Pr){sub 2}{r{underscore}brace}{sub 2}Ga{sub 2}Me{sub 3}{sup +} (2b{sup +}), whose structure and dynamic properties are similar to those of 2a{sup +}. The reaction of the bulkier {sup t}Bu-substituted amidinate complexes {l{underscore}brace}{sup t}BuC(N{sup i}Pr){sub 2}{r{underscore}brace}MMe{sub 2} (M - Al, 6a; M - Ga, 6b) with 0.5 equiv of [Ph{sub 3}C][B(C{sub 6}F{sub 5}){sub 4}] yields {l{underscore}brace}{sup t}BuC(N{sup i}Pr){sub 2}{r

  4. Model updating of complex structures using the combination of component mode synthesis and Kriging predictor.

    PubMed

    Liu, Yang; Li, Yan; Wang, Dejun; Zhang, Shaoyi

    2014-01-01

    Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM). Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS) technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM) to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters.

  5. Model Updating of Complex Structures Using the Combination of Component Mode Synthesis and Kriging Predictor

    PubMed Central

    Li, Yan; Wang, Dejun; Zhang, Shaoyi

    2014-01-01

    Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM). Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS) technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM) to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters. PMID:24634612

  6. Unsaturated platinum-rhenium cluster complexes. Synthesis, structures and reactivity.

    PubMed

    Adams, Richard D; Captain, Burjor; Smith, Mark D; Beddie, Chad; Hall, Michael B

    2007-05-09

    Two new compounds PtRe3(CO)12(PBut3)(micro-H)3, 9, and PtRe2(CO)9(PBut3)(micro-H)2, 10, were obtained from the reaction of Pt(PBut3)2 with Re3(CO)12(micro-H3), 8, at room temperature. Compound 9 contains a butterfly cluster of four metals formed by the insertion of the platinum atom from a Pt(PBut3) group into one of the hydride-bridged metal-metal bonds of 8. The three hydrido ligands are bridging ligands across each of three new Pt-Re bonds. Compound 10 contains a triangular PtRe2 cluster with two hydrido ligands; one bridges a Pt-Re bond, and the other bridges the Re-Re bond. The new compound Pt2Re2(CO)7(PBut3)2(micro-H)2, 11, was obtained from the reaction of 8 with Pt(PBut3)2 in hexane at reflux. Compound 11 was also obtained from 10 by reaction with an additional quantity of Pt(PBut3)2. Compound 11 contains a tetrahedral cluster of four metal atoms with two dynamically active hydrido ligands. A CO ligand on one of the two platinum atoms also exchanges between the two platinum atoms rapidly on the NMR time scale. Compound 11 is electronically unsaturated and was found to add hydrogen at room temperature to form the tetrahydrido cluster complex, Pt2Re2(CO)7(PBut3)2(micro-H)4, 12. Compound 12 has a structure similar to 11 but contains one triply bridging hydrido ligand, two edge bridging hydrido ligands, and one terminal hydrido ligand on one of the two platinum atoms. A kinetic isotope effect D/H of 1.5(1) was determined for the addition of H2 to 11. Hydrogen can be eliminated from 12 by heating to 97 degrees C or by the application of UV-vis irradiation at room temperature. Compound 12 adds CO at room temperature to yield the complex Pt2Re2(CO)8(PBut3)2(micro-H)4, 13, which contains a planar cluster of four metal atoms with a Pt-Pt bond and four edge bridging hydrido ligands. Compounds 11 and 12 react with Pt(PBut3)2 to yield the known five metal cluster complexes Pt3Re2(CO)6(PBut3)3(micro-H)2, 14, and Pt3Re2(CO)6(PBut3)3(micro-H)4, 15, respectively. Density

  7. 1D cerium(III) coordination polymer with pivalate bridges: Synthesis, structure and magnetic properties

    NASA Astrophysics Data System (ADS)

    Akhtar, Muhammad Nadeem; Mateen, Muhammad; Sadakiyo, Masaaki; Warsi, Muhammad Farooq; AlDamen, Murad A.; Song, You

    2017-08-01

    In the present work, synthesis, characterization, and properties of a new 1D-polymeric chain of [Ce(piv)3(MeOH)2]n (1D-Ce) are described. This polymeric structure was synthesized via reaction of Ce(NO3)3·6H2O with pivalic acid in presence of triethylamine. Crystal structure consists of cerium coordinated to eight oxygen atoms from five pivalate and two methanol moieties. Magnetic studies on the complex revealed a strong antiferromagnetic interaction between CeIII ions in the 1D chain.

  8. Synthesis, Structure, and Properties of Ca2ZnN2

    DTIC Science & Technology

    1990-04-30

    ternary nitride CaiZnN9, prepared by the reaction of Ca3N2 and Zn in NT gas at 680-. The structure, determined by x-ray powder diffraction and...ZnN 2, prepared by the reaction of Ca 3N2 and Zn in N2 gas at 680 0 C. The structure, determined by x-ray powder diffraction and refined by Rietveld...properties of Ca2ZnN2. Experimental Synthesis All manipulations were carried out in an argon-filled glove box. Calcium nitride was first prepared by

  9. Synthesis, structure and reactivity of rare-earth metal complexes containing anionic phosphorus ligands.

    PubMed

    Li, Tianshu; Kaercher, Sabrina; Roesky, Peter W

    2014-01-07

    A comprehensive review of structurally characterized rare-earth metal complexes containing anionic phosphorus ligands is presented. Since rare-earth elements form hard ions and phosphorus is considered as a soft ligand, the rare-earth metal phosphorus coordination is regarded as a less favorite combination. Three classes of phosphorus ligands, (1) the monoanionic organophosphide ligands (PR2(-)) bearing one negative charge on the phosphorus atom; (2) the dianionic phosphinidene (PR(2-)) and P(3-) ligands; and (3) the pure inorganic polyphosphide ligands (Pn(x-)), are included here. Particular attention has been paid to the synthesis, structure, and reactivity of the rare-earth metal phosphides.

  10. Active control synthesis for flexible space structures excited by persistent disturbances

    NASA Technical Reports Server (NTRS)

    Wie, Bong; Gonzalez, Marcelo

    1990-01-01

    Both classical and state-space synthesis methods for active control of flexible space structures in the presence of persistent disturbances are presented. The methods exploit the so-called internal model principle for asymptotic disturbance rejection. A generic example of flexible space structures is used to illustrate the simplicity of the proposed design methodologies. The concept of a disturbance rejection filter dipole is introduced from a classical control viewpoint. It is shown that the proposed design methods will invariably make use of non-minimum-phase compensation for a class of noncolocated control problems. The need for tradeoffs between performance and parameter robustness is discussed.

  11. Synthesis, characterization and structural aspects of new haptens for PAHs

    NASA Astrophysics Data System (ADS)

    Li, Yi; Yang, Mingming; Liu, Yuanyuan; Wei, Rongqing; Liu, Xiaoning; Li, Fangshi

    2011-02-01

    Two new haptens for PAHs, 4-(naphthalen-2-yl)-4-oxobutanoic acid ( I) and 4-(anthracen-1-yl)-4-oxobutanoic acid ( II), were synthesized and confirmed by elemental analysis, IR, and 1H NMR. Single crystal X-ray structure showed that compound I crystallizes in the triclinic crystal system (space group = P-1). A classic hydrogen bonded dimer is formed by the carboxylic acid group from two molecules. The R22 ( 8) graph-set motif links the molecules into pairs around inversion centers in the unit cell. The O-H⋯O hydrogen-bonded interactions involving these pairs are very strong and stabilize molecular packing of these dimers into a unique assembly. Compound II crystallizes in the Monoclinic crystal system (space group = P21/c). Similarly to compound I, a classic hydrogen bonded dimer is formed by the carboxylic acid group from two molecules. The R22 ( 8) graph-set motif links the molecules into pairs around inversion centers in the unit cell. Besides, an intramolecular hydrogen bonding causes the formation of a planar six-membered ring, which is also coplanar with the adjacent anthracene ring. The geometries of the corresponding parts of the haptens are almost the same as those of naphthalene and anthracene. Ab initio Hartree-Fock computational calculation provided the supports that the size, shape (geometry) and electronic properties at the corresponding parts of the haptens did not change significantly, compared to those of naphthalene and anthracene. The haptens were coupled with bovine serum albumin (BSA) to make antigents. The coupling ratio of I- BSA was 1:20, and II-BSA 1:37, respectively. These results showed that the new haptens could be used to induce specific antibodies for PAHs.

  12. Synthesis, Chemistry, and Electronic Structures of Group 9 Metallaboranes.

    PubMed

    Borthakur, Rosmita; Kar, Sourav; Barik, Subrat Kumar; Bhattacharya, Somnath; Kundu, Gargi; Varghese, Babu; Ghosh, Sundargopal

    2017-02-06

    Dimetallaoctaborane(12) of Ru, Co, and Rh have been well-characterized by a range of spectroscopic techniques and X-ray diffraction studies. Thus, reinvestigation of the Ir-system became of interest. As a result, a slight modification in the reaction conditions enabled us to isolate the missing Ir analogue of octaborane(12), [(Cp*Ir)2B6H10], 1. Compound 1 adapts a geometry similar to that of its parent octaborane(12) and Ru, Co, and Rh analogues. In [M2B6H10+x](M = Ru, x = 2; M = Co and Rh, x = 0), there exist two M-H-B protons. However, a significant difference observed in [(Cp*Ir)2B6H10] is the presence of two Ir-H instead of Ir-H-B protons that eventually controls the reactivity of this molecule. For example, unlike [M2B6H10](M = Co or Rh), the Ir-analogue does not react with metal carbonyl compounds or [Au(PPh3)Cl]. Along with 1, a closo trimetallic 8-vertex iridaborane [(Cp*Ir)3B5H4Cl], 2 was also isolated. Additionally, from another reaction, 12-vertex closo iridaboranes [(Cp*Ir)2B10Hy(OH)z], 3a and 3b (3a: y = 12, z = 0; 3b: y = 8, z = 2), have also been isolated. Further, density functional theory calculations were performed to gain useful insight into the structure and stability of these compounds.

  13. Synthesis, structural, spectroscopic and biological studies of Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Diab, M. A.; El-Sonbati, A. Z.; Shoair, A. F.; Eldesoky, A. M.; El-Far, N. M.

    2017-08-01

    Schiff base ligand 4-((pyridin-2- yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (PDMP) and its complexes were prepared and characterized on the basis of elemental analysis, IR, mass spectra and thermogravimetric analysis. All results confirm that the complexes have 1:1 (M: PMDP) stoichiometric formula [M(PMDP)Cl2H2O ] (M = Cu(II), Co(II), Ni(II) and Mn(II)), [Cd(PMDP)Cl2] and the ligand behaves as a bi/tridentate forming five-membered chelating ring towards the metal ions, bonding through azomethine nitrogen/exocyclic carbonyl oxygen, azomethine pyridine nitrogen and exocyclic carbonyl oxygen. The shift in the band positions of the groups involved in coordination has been utilized to estimate the metal-nitrogen and/or oxygen bond lengths. The complexes of Co(II), Ni(II) and Cu(II) are paramagnetic and the magnetic as well as spectral data suggest octahedral geometry, whereas the Cd(II) complex is tetrahedral. The XRD studies show that both the ligand and its metal complexes (1 and 3) show polycrystalline with crystal structure. Molecular docking was used to predict the binding between PMDP ligand and the receptors. The corrosion inhibition of mild steel in 2 M HCl solution by PDMP was explored utilizing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and (EFM) electrochemical frequency modulation method. Potentiodynamic polarization demonstrated that PDMP compound is mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the protective ability. The percentage of inhibition efficiency was found to increase with increasing the inhibitor concentration.

  14. Synthesis and structural characterization of five zinc bisphosphonate compounds

    NASA Astrophysics Data System (ADS)

    Ni, Ai-Yun; Pan, Jie; Xue, Zhen-Zhen; Han, Song-De; Li, Jin-Hua; Wang, Guo-Ming; Wang, Zong-Hua

    2017-08-01

    The hydrothermal reaction of zinc ions with 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) in the presence of additives such as 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,3-propanediamine, imidazole and isonipecotic acid, afforded five metal phosphonates, namely, [H2DABCO]{Zn3[CH3C(OH)(PO3)2]2} (1), [C3H14N2]{Zn3[CH3C(OH)(PO3)2]2} (2), [C3H5N2]2{Zn3[CH3C(OH)(PO3)2]2} (3), {Zn2[CH3C(OH)(PO3)2][C3H4N2]2} (4) and {Zn2[CH3C(OH)(PO3)2][C6H11NO2]2[H2O]2}·H2O (5). Compounds 1 and 2 are isostructural and adopt a pillar-layered 3D structure. Compound 3 is a 3D framework in which [ZnO4] tetrahedra are connected by HEDP molecules with tetradentate mode. The [ZnO3N] tetrahedra in 4 shares corners with the [CPO3] tetrahedra into a 3D framework with twelve-membered ring. It is also found that 4 displays interesting left-handed helical chains along [100] direction. In 5, HEDP molecules exhibit tetradentate coordination fashion to combine Zn atoms into a complicated 2D hybrid layer, resulting in the coordinated isonipecotic acid rings being sandwiched between the layers. All the compounds have been characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses.

  15. The Nuclear Magnetic Resonance of CCCC RNA Reveals a Right-Handed Helix, and Revised Parameters for AMBER Force Field Torsions Improve Structural Predictions from Molecular Dynamics

    PubMed Central

    2013-01-01

    The sequence dependence of RNA energetics is important for predicting RNA structure. Hairpins with Cn loops are consistently less stable than hairpins with other loops, which suggests the structure of Cn regions could be unusual in the “unfolded” state. For example, previous nuclear magnetic resonance (NMR) evidence suggested that polycytidylic acid forms a left-handed helix. In this study, UV melting experiments show that the hairpin formed by r(5′GGACCCCCGUCC) is less stable than r(5′GGACUUUUGUCC). NMR spectra for single-stranded C4 oligonucleotide, mimicking the unfolded hairpin loop, are consistent with a right-handed A-form-like helix. Comparisons between NMR spectra and molecular dynamics (MD) simulations suggest that recent reparametrizations, parm99χ_YIL and parm99TOR, of the AMBER parm99 force field improve the agreement between structural features for C4 determined by NMR and predicted by MD. Evidently, the force field revisions to parm99 improve the modeling of RNA energetics and therefore structure. PMID:23286901

  16. Synthesis, Oxidation Behavior, Crystallization and Structure of 2'-Methylseleno Guanosine Containing RNAs

    SciTech Connect

    Moroder,H.; Kreutz, C.; Lang, K.; Serganov, A.; Micura, R.

    2006-01-01

    We have recently introduced a basic concept for the combined chemical and enzymatic preparation of site-specifically modified 2'-methylseleno RNAs which represent useful derivatives for phasing of X-ray crystallographic data during their three-dimensional structure determination. Here, we introduce the first synthesis of an appropriate guanosine phosphoramidite, which complements the thus far established set of 2'-methylseleno-modified uridine, cytidine, and adenosine building blocks for solid-phase synthesis. The novel building block was readily incorporated into RNA. Importantly, it was the 2'-methylseleno-guanosine-labeled RNA that allowed us to reveal the reversible oxidation/reduction behavior of the Se moiety and thus it represents a valuable contribution to the understanding of the action of threo-1,4-dimercapto-2,3-butanediol (DTT) required during solid-phase synthesis, deprotection, and crystallization of selenium-containing RNA. In addition, we investigated 2'-methylseleno RNA with respect to crystallization properties. Our studies revealed that the Se modification significantly increases the range of conditions leading to crystal growth. Moreover, we determined the crystal structures of model RNA helices and showed that the Se modification can affect crystal packing interactions, thus potentially expanding the possibilities for obtaining the best crystal form.

  17. Grafting in revision rhinoplasty.

    PubMed

    Bussi, M; Palonta, F; Toma, S

    2013-06-01

    Rhinoplasty is one of the most difficult aesthetic surgery procedures with a high rate of revision. In revision rhinoplasty the surgeon should explore the patient's concerns and then verify the possibility to satisfy expectations after complete internal and external examination of the nose. For the vast majority of complex secondaries, an open approach is the only reasonable method. In fact, in secondary nasal surgery, because of the scarring process following the primary operation, dissection is tedious, and landmarks are lost. One of the main objectives for the surgeon who approaches secondary rhinoplasty is to restore the structural support of the nose and to replace the lost volume of soft tissues. To achieve this purpose, the surgeon must often rely on grafts. An ideal grafting material must be easy to sculpt, resistant to trauma, infection and extrusion, mechanically stable, inert and readily available. For all these reasons, autogenous cartilage grafts harvested from septum, auricular concha and rib represent the first choice in rhinoplasty. In order to obtain a camouflage graft that provides natural contouring to the nose, temporalis fascia can be used. All these carefully trimmed grafts are useful in tip revision surgery, in secondary surgery of the dorsum and to resolve or reduce functional problems.

  18. Recognizing magnetic structures by present and future radio telescopes with Faraday rotation measure synthesis

    NASA Astrophysics Data System (ADS)

    Beck, R.; Frick, P.; Stepanov, R.; Sokoloff, D.

    2012-07-01

    Context. Modern radio telescopes allow us to record a large number of spectral channels. The application of a Fourier transform to spectropolarimetric data in radio continuum, Faraday rotation measure (RM) synthesis, yields the “Faraday spectrum”, which hosts valuable information about the magneto-ionic medium along the line of sight. Aims: We investigate whether the method of wavelet-based RM synthesis can help us to identify structures of regular and turbulent magnetic fields in extended magnetized objects, such as galaxies and galaxy clusters. Methods: The analysis of spectropolarimetric radio observations of multi-scale targets calls for a corresponding mathematical technique. Wavelets allow us to reformulate the RM synthesis method in a scale-dependent way and to visualize the data as a function of Faraday depth and scale. Results: We present observational tests to recognize magnetic field structures. A region with a regular magnetic field generates a broad “disk” in Faraday space, with two “horns” when the distribution of cosmic-ray electrons is broader than that of the thermal electrons. Each field reversal generates one asymmetric “horn” on top of the “disk”. A region with a turbulent field can be recognized as a “Faraday forest” of many components. These tests are applied to the spectral ranges of various synthesis radio telescopes. We argue that the ratio of maximum to minimum wavelengths determines the range of scales that can be identified in Faraday space. Conclusions: A reliable recognition of magnetic field structures in spiral galaxies or galaxy clusters requires the analysis of data cubes in position-position-Faraday depth space (“PPF cubes”), observed over a wide and continuous frequency range, allowing the recognition of a wide range of scales as well as high resolution in Faraday space. The planned Square Kilometre Array (SKA) will fulfill this condition and will be close to representing a perfect

  19. Biologically Inspired Synthesis Route to Three-Dimensionally Structured Inorganic Thin Films

    DOE PAGES

    Schwenzer, Birgit; Morse, Daniel E.

    2008-01-01

    Inorganic thin films (hydroxide, oxide, and phosphate materials) that are textured on a submicron scale have been prepared from aqueous metal salt solutions at room temperature using vapor-diffusion catalysis. This generic synthesis approach mimics the essential advantages of the catalytic and structure-directing mechanisms observed for the formation of silica skeletons of marine sponges. Chemical composition, crystallinity, and the three-dimensional morphology of films prepared by this method are extremely sensitive to changes in the synthesis conditions, such as concentrations, reaction times, and the presence and nature of substrate materials. Focusing on different materials systems, the reaction mechanism for the formation ofmore » these thin films and the influence of different reaction parameters on the product are explained.« less

  20. Synthesis of the first tellurium-derivatized oligonucleotides for structural and functional studies.

    PubMed

    Sheng, Jia; Hassan, Abdalla E A; Huang, Zhen

    2009-10-05

    We report here the first synthesis of Te-nucleoside phosphoramidites and Te-modified oligonucleotides. We protected the 2'-tellurium functionality by alkylation and found that the Te functionality is compatible with solid-phase synthesis and that the Te oligonucleotides are stable during deprotection and purification. In addition, the redox properties of the Te functionalities have been explored. We found that the telluride and telluoxide DNAs are interchangeable by redox reactions. At elevated temperature, the Te-DNA can also be site-specifically fragmented oxidatively or reductively when 2'-TePh functionality is present, whereas elimination of the nucleobase is observed in the presence of 2'-TeMe. Moreover, the stability of the DNA duplexes derivatized with the Te functionalities has been investigated. Our Te derivatization of nucleic acids provides a novel approach for investigating DNA damage as well as for structure and function studies of nucleic acids and their protein complexes.

  1. Synthesis of regional crust and upper-mantle structure from seismic and gravity data

    NASA Technical Reports Server (NTRS)

    Alexander, S. S.; Lavin, P. M.

    1979-01-01

    Available seismic and ground based gravity data are combined to infer the three dimensional crust and upper mantle structure in selected regions. This synthesis and interpretation proceeds from large-scale average models suitable for early comparison with high-altitude satellite potential field data to more detailed delineation of structural boundaries and other variations that may be significant in natural resource assessment. Seismic and ground based gravity data are the primary focal point, but other relevant information (e.g. magnetic field, heat flow, Landsat imagery, geodetic leveling, and natural resources maps) is used to constrain the structure inferred and to assist in defining structural domains and boundaries. The seismic data consists of regional refraction lines, limited reflection coverage, surface wave dispersion, teleseismic P and S wave delay times, anelastic absorption, and regional seismicity patterns. The gravity data base consists of available point gravity determinations for the areas considered.

  2. Synthesis design and structure of a multipore zeolite with interconnected 12- and 10-MR channels.

    PubMed

    Moliner, Manuel; Willhammar, Tom; Wan, Wei; González, Jorge; Rey, Fernando; Jorda, Jose L; Zou, Xiaodong; Corma, Avelino

    2012-04-11

    A new molecular sieve, ITQ-38, containing interconnected large and medium pores in its structure has been synthesized. The rational combination of dicationic piperidine-derivative molecules as organic structure directing agents (OSDAs) with germanium and boron atoms in alkaline media has allowed the synthesis of ITQ-38 zeolite. High-resolution transmission electron microscopy (HRTEM) has been used to elucidate the framework topology of ITQ-38, revealing the presence of domains of perfect ITQ-38 crystals as well as very small areas containing nanosized ITQ-38/ITQ-22 intergrowths. The structure of ITQ-38 is highly related to ITQ-22 and the recently described polymorph C of ITQ-39 zeolite. It shares a common building layer with ITQ-22 and contains the same building unit as the polymorph C of ITQ-39. All three structures present similar framework density, 16.1 T atoms/1000 Å(3).

  3. Synthesis and structural characterization of some trisulfide analoges of thiouracil-based antithyroid drugs

    NASA Astrophysics Data System (ADS)

    Bhabak, Krishna P.; Bhowmick, Debasish

    2012-08-01

    Thiourea-based antithyroid drugs are effectively used for the treatment of hyperthyroidism. In this paper, we describe the synthesis of new trisulfides (11-12) from the commonly used thiourea-based antithyroid drugs such as 6-n-propyl-2-thiouracil (PTU) and 6-methyl-2-thiouracil (MTU) in the reaction with I2/KI system. Structural analysis by single crystal X-ray diffraction studies revealed the stabilization of trisulfides by a lactam-lactim tautomerism facilitating effective intramolecular as well as intermolecular non-covalent interactions. Although the structures of both trisulfides were found to be quite similar, a notable difference in the intermolecular interactions was observed between compounds 11 and 12 leading to different structural patterns. Structural stabilization of these trisulfides by tautomerism followed by intramolecular as well as intermolecular H-bonds makes these molecules as perfect examples in molecular recognition with self-complementary donor and acceptor units within a single molecule.

  4. Local structure of ZnO micro flowers and nanoparticles obtained by micro segmented flow synthesis

    SciTech Connect

    Li, Shuning; Roy, Amitava; Lichtenberg, Henning; Merchan, Gregory; Kumar, Challa S.S.R.; Köhler, J. Michael

    2012-03-07

    The micro-segmented flow technique was applied for continuous synthesis of ZnO micro- and nanoparticles with short residence times of 9.4 s and 21.4 s, respectively. The obtained particles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Small angle X-ray scattering (SAXS) and photoluminescence spectroscopy were used to determine the size and optical properties of ZnO nanoparticles. In addition, extended X-ray absorption fine structure (EXAFS) spectroscopy was employed to investigate local structural properties. The EXAFS measurements reveal a larger degree of structural disorder in the nanoparticles than the microparticles. These structural changes should be taken into consideration while evaluating the size-dependent visible emission of ZnO nanoparticles.

  5. Structural basis of high-fidelity DNA synthesis by yeast DNA polymerase [delta

    SciTech Connect

    Swan, Michael K.; Johnson, Robert E.; Prakash, Louise; Prakash, Satya; Aggarwal, Aneel K.

    2009-09-25

    DNA polymerase {delta} (Pol {delta}) is a high-fidelity polymerase that has a central role in replication from yeast to humans. We present the crystal structure of the catalytic subunit of yeast Pol {delta} in ternary complex with a template primer and an incoming nucleotide. The structure, determined at 2.0-{angstrom} resolution, catches the enzyme in the act of replication, revealing how the polymerase and exonuclease domains are juxtaposed relative to each other and how a correct nucleotide is selected and incorporated. The structure also reveals the 'sensing' interactions near the primer terminus, which signal a switch from the polymerizing to the editing mode. Taken together, the structure provides a chemical basis for the bulk of DNA synthesis in eukaryotic cells and a framework for understanding the effects of cancer-causing mutations in Pol {delta}.

  6. Synthesis of ultralarge-pore FDU-12 silica with face-centered cubic structure.

    PubMed

    Huang, Liang; Yan, Xuewu; Kruk, Michal

    2010-09-21

    Ultralarge-pore FDU-12 (ULP-FDU-12) silicas with face-centered cubic structures (Fm3m symmetry) of spherical mesopores were synthesized at low initial temperature (∼14 °C) using commercially available PEO-PPO-PEO triblock copolymer Pluronic F127 as a micellar template and xylene as a micelle expander. Xylene was selected on the basis of its predicted higher swelling ability for the Pluronic surfactant micelles in comparison to 1,3,5-trimethylbenzene that was used previously to obtain large-pore FDU-12. The optimization of the synthesis conditions afforded as-synthesized ULP-FDU-12 materials with unit-cell parameters up to 56 nm, which is comparable to the highest reported values for Fm3m structures templated by custom-made surfactants. Calcined silicas were obtained with unit-cell parameters up to 53 nm and pore diameters up to ∼36 nm (for N(2) adsorption at 77 K, the capillary condensation relative pressure was up to 0.938). The preferred silica source was tetraethylorthosilicate, but tetramethylorthosilicate was also found suitable. The pore diameter was dependent on the unit-cell size of the as-synthesized material, but was further tuned by adjusting the time and temperature of the treatment in the HCl solution. If the synthesis was performed at low temperature only, highly ordered closed-pore silicas were obtained at calcination temperatures as low as 450 °C. On the other hand, the hydrothermal treatments, including the acid treatment at 130 °C, afforded silicas with large pore entrance sizes. The present synthesis constitutes a major advancement in the synthesis of ordered silicas with very large open and closed spherical mesopores.

  7. Antineoplastic Agents 579. Synthesis and Cancer Cell Growth Evaluation of E-Stilstatin 3: A Resveratrol Structural Modification⊥

    PubMed Central

    Pettit, George R.; Melody, Noeleen; Thornhill, Andrew; Knight, John C.; Groy, Thomas L.; Herald, Cherry L.

    2009-01-01

    As an extension of our earlier structure/activity investigation of resveratrol (1a) cancer cell growth inhibitory activity compared to the structurally related stilbene combretastatin series (e.g., 2a), an efficient synthesis of E-stilstatin 3 (3a) and its phosphate prodrug 3b was completed. The trans-stilbene 3a was obtained using a convergent synthesis employing a Wittig reaction with phosphonium bromide 9 as the key reaction step. Deprotection of the Z-silyl ether 13 gave E-stilstatin 3 (3a) as the exclusive product. The structure and stereochemistry of 3a was confirmed by X-ray crystal structure determination. PMID:19719153

  8. Highly mismatched GaN1-x Sb x alloys: synthesis, structure and electronic properties

    NASA Astrophysics Data System (ADS)

    Yu, K. M.; Sarney, W. L.; Novikov, S. V.; Segercrantz, N.; Ting, M.; Shaw, M.; Svensson, S. P.; Martin, R. W.; Walukiewicz, W.; Foxon, C. T.

    2016-08-01

    Highly mismatched alloys (HMAs) is a class of semiconductor alloys whose constituents are distinctly different in terms of size, ionicity and/or electronegativity. Electronic properties of the alloys deviate significantly from an interpolation scheme based on small deviations from the virtual crystal approximation. Most of the HMAs were only studied in a dilute composition limit. Recent advances in understanding of the semiconductor synthesis processes allowed growth of thin films of HMAs under non-equilibrium conditions. Thus reducing the growth temperature allowed synthesis of group III-N-V HMAs over almost the entire composition range. This paper focuses on the GaN x Sb1-x HMA which has been suggested as a potential material for solar water dissociation devices. Here we review our recent work on the synthesis, structural and optical characterization of GaN1-x Sb x HMA. Theoretical modeling studies on its electronic structure based on the band anticrossing (BAC) model are also reviewed. In particular we discuss the effects of growth temperature, Ga flux and Sb flux on the incorporation of Sb, film microstructure and optical properties of the alloys. Results obtained from two separate MBE growths are directly compared. Our work demonstrates that a large range of direct bandgap energies from 3.4 eV to below 1.0 eV can be achieved for this alloy grown at low temperature. We show that the electronic band structure of GaN1-x Sb x HMA over the entire composition range is well described by a modified BAC model which includes the dependence of the host matrix band edges as well as the BAC model coupling parameters on composition. We emphasize that the modified BAC model of the electronic band structure developed for the full composition of GaN x Sb1-x is general and is applicable to any HMA.

  9. Synthesis and single crystal structure refinement of the one-layer hydrate of sodium brittle mica

    SciTech Connect

    Kalo, Hussein; Milius, Wolfgang; Braeu, Michael; Breu, Josef

    2013-02-15

    A sodium brittle mica with the ideal composition [Na{sub 4}]{sup inter}[Mg{sub 6}]{sup oct}[Si{sub 4}Al{sub 4}]{sup tet}O{sub 20}F{sub 4} was synthesized via melt synthesis in a gas tight crucible. This mica is unusual inasmuch as the known mica structure holds only room for two interlayer cations per unit cell and inasmuch as it readily hydrates despite the high layer charge while ordinary micas and brittle micas are non-swelling. The crystal structure of one-layer hydrate sodium brittle mica was determined and refined from single crystal X-ray data. Interlayer cations reside at the center of the distorted hexagonal cavities and are coordinated by the three inner basal oxygen atoms. The coordination of the interlayer cation is completed by three interlayer water molecules residing at the center of the interlayer region. The relative position of adjacent 2:1-layers thus is fixed by these octahedrally coordinated interlayer cations. Pseudo-symmetry leads to extensive twinning. In total five twin operations generate the same environment for the interlayer species and are energetically degenerate. - Graphical abstract: The sodium brittle mica has been successfully synthesized by melt synthesis and the crystal structure of the one-layer hydrate of sodium brittle mica was determined from single crystal X-ray diffraction data. Highlights: Black-Right-Pointing-Pointer Melt synthesis yielded coarse grained sodium brittle mica which showed little disorder. Black-Right-Pointing-Pointer Sodium brittle mica hydrated completely to the state of one-layer hydrate. Black-Right-Pointing-Pointer Structure of one-layer hydrate of sodium brittle mica could therefore be determined and refined. Black-Right-Pointing-Pointer Arrangement of upper and lower tetrahedral sheet encompassing interlayer cation were clarified.

  10. Structure-directing effects of ionic liquids in the ionothermal synthesis of metal–organic frameworks

    PubMed Central

    Kelley, Steven P.; Rogers, Robin D.

    2017-01-01

    Traditional synthesis of metal–organic frameworks (MOFs) involves the reaction of a metal-containing precursor with an organic linker in an organic solvent at an elevated temperature, in what is termed a ‘solvothermal’ reaction. More recently, many examples have been reported of MOF synthesis in ionic liquids (ILs), rather than an organic solvent, in ‘ionothermal’ reactions. The high concentration of both cations and anions in an ionic liquid allows for the formation of new MOF structures in which the IL cation or anion or both are incorporated into the MOF. Most commonly, the IL cation is included in the open cavities of the MOF, countering the anionic charge of the MOF framework itself and acting as a template around which the MOF structure forms. Ionic liquids can also serve other structure-directing roles, for example, when an IL containing a single enantiomer of a chiral anion leads to a homochiral MOF, even though the IL anion is not itself incorporated into the MOF. A comprehensive review of ionothermal syntheses of MOFs, and the structure-directing effects of the ILs, is given. PMID:28875025

  11. Structure-directing effects of ionic liquids in the ionothermal synthesis of metal-organic frameworks.

    PubMed

    Vaid, Thomas P; Kelley, Steven P; Rogers, Robin D

    2017-07-01

    Traditional synthesis of metal-organic frameworks (MOFs) involves the reaction of a metal-containing precursor with an organic linker in an organic solvent at an elevated temperature, in what is termed a 'solvothermal' reaction. More recently, many examples have been reported of MOF synthesis in ionic liquids (ILs), rather than an organic solvent, in 'ionothermal' reactions. The high concentration of both cations and anions in an ionic liquid allows for the formation of new MOF structures in which the IL cation or anion or both are incorporated into the MOF. Most commonly, the IL cation is included in the open cavities of the MOF, countering the anionic charge of the MOF framework itself and acting as a template around which the MOF structure forms. Ionic liquids can also serve other structure-directing roles, for example, when an IL containing a single enantiomer of a chiral anion leads to a homochiral MOF, even though the IL anion is not itself incorporated into the MOF. A comprehensive review of ionothermal syntheses of MOFs, and the structure-directing effects of the ILs, is given.

  12. Plasmon-mediated synthesis of silver cubes with unusual twinning structures using short wavelength excitation.

    PubMed

    Personick, Michelle L; Langille, Mark R; Zhang, Jian; Wu, Jinsong; Li, Shuyou; Mirkin, Chad A

    2013-06-10

    The plasmon-mediated synthesis of silver nanoparticles is a versatile synthetic method which leverages the localized surface plasmon resonance (LSPR) of nanoscale silver to generate particles with non-spherical shapes and control over dimensions. Herein, a method is reported for controlling the twinning structure of silver nanoparticles, and consequently their shape, via the plasmon-mediated synthesis, solely by varying the excitation wavelength between 400, 450, and 500 nm, which modulates the rate of Ag⁺ reduction. Shorter, higher energy excitation wavelengths lead to faster rates of reaction, which in turn yield structures containing a greater number of twin boundaries. With this method, silver cubes can be synthesized using 450 nm excitation, which represents the first time this shape has been realized by a plasmon-mediated synthetic approach. In addition, these cubes contain an unusual twinning structure composed of two intersecting twin boundaries or multiple parallel twin boundaries. With respect to their twinning structure, these cubes fall between planar-twinned and multiply twinned nanoparticles, which are synthesized using 500 and 400 nm excitation, respectively.

  13. Homodecoupled 1,1- and 1,n-ADEQUATE: Pivotal NMR Experiments for the Structure Revision of Cryptospirolepine.

    PubMed

    Saurí, Josep; Bermel, Wolfgang; Buevich, Alexei V; Sherer, Edward C; Joyce, Leo A; Sharaf, Maged H M; Schiff, Paul L; Parella, Teodor; Williamson, R Thomas; Martin, Gary E

    2015-08-24

    Cryptospirolepine is the most structurally complex alkaloid discovered and characterized thus far from any Cryptolepis specie. Characterization of several degradants of the original, sealed NMR sample a decade after the initial report called the validity of the originally proposed structure in question. We now report the development of improved, homodecoupled variants of the 1,1- and 1,n-ADEQUATE (HD-ADEQUATE) NMR experiments; utilization of these techniques was critical to successfully resolving long-standing structural questions associated with crytospirolepine.

  14. Cross-cultural examination of the structure of the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R).

    PubMed

    Botti, Mari; Khaw, Damien; Jørgensen, Emmy Brandt; Rasmussen, Bodil; Hunter, Susan; Redley, Bernice

    2015-08-01

    This study investigated the cross-cultural factor stability and internal consistency of the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R), a measure of the quality of postoperative pain management used internationally. We conducted exploratory factor analysis (EFA) of APS-POQ-R data from 2 point prevalence studies comprising 268 and 311 surveys of Danish and Australian medical-surgical patients, respectively. Parallel analysis indicated 4- and 3-factor solutions for Danish and Australian patients, respectively, which accounted for 58.1% and 52.9% of variance. Internal consistency was unsatisfactory among both Danish (Cronbach α = .54) and Australian (Cronbach α = .63) cohorts. There was a high degree of between-group similarity in item-factor loadings of variables coded as "pain experience," but not "pain management." This finding reflected cross-cultural differences in ratings of treatment satisfaction. For Danish patients, satisfaction was associated with the degree of pain severity and activity interference, whereas for Australian patients, satisfaction was associated with their perceived ability to participate in treatment. To facilitate further cross-cultural comparison, we compared our findings with past research conducted in the United States and Iceland. EFA supported the construct validity of the APS-POQ-R as a measure of "pain experience" but indicated that items measuring "pain management" may vary cross-culturally. Findings highlighted the need for further validation of the APS-POQ-R internationally. This study revealed the APS-POQ-R as a valid measure of postoperative pain experience for Danish and Australian patients. Measures of patients' perception of pain management were not robust to group differences in treatment expectations and demonstrated cross-cultural instability. Results highlighted the difficulties in establishing stable cross-cultural, cross-population subscales for the APS-POQ-R. Copyright © 2015

  15. Intricate Hollow Structures: Controlled Synthesis and Applications in Energy Storage and Conversion.

    PubMed

    Zhou, Liang; Zhuang, Zechao; Zhao, Huihui; Lin, Mengting; Zhao, Dongyuan; Mai, Liqiang

    2017-02-07

    Intricate hollow structures garner tremendous interest due to their aesthetic beauty, unique structural features, fascinating physicochemical properties, and widespread applications. Here, the recent advances in the controlled synthesis are discussed, as well as applications of intricate hollow structures with regard to energy storage and conversion. The synthetic strategies toward complex multishelled hollow structures are classified into six categories, including well-established hard- and soft-templating methods, as well as newly emerging approaches based on selective etching of "soft@hard" particles, Ostwald ripening, ion exchange, and thermally induced mass relocation. Strategies for constructing structures beyond multishelled hollow structures, such as bubble-within-bubble, tube-in-tube, and wire-in-tube structures, are also covered. Niche applications of intricate hollow structures in lithium-ion batteries, Li-S batteries, supercapacitors, Li-O2 batteries, dye-sensitized solar cells, photocatalysis, and fuel cells are discussed in detail. Some perspectives on the future research and development of intricate hollow structures are also provided.

  16. The structure of Diagnostic and Statistical Manual of Mental Disorders (4th edition, text revision) personality disorder symptoms in a large national sample.

    PubMed

    Trull, Timothy J; Vergés, Alvaro; Wood, Phillip K; Jahng, Seungmin; Sher, Kenneth J

    2012-10-01

    We examined the latent structure underlying the criteria for DSM-IV-TR (American Psychiatric Association, 2000, Diagnostic and statistical manual of mental disorders (4th ed., text revision). Washington, DC: Author.) personality disorders in a large nationally representative sample of U.S. adults. Personality disorder symptom data were collected using a structured diagnostic interview from approximately 35,000 adults assessed over two waves of data collection in the National Epidemiologic Survey on Alcohol and Related Conditions. Our analyses suggested that a seven-factor solution provided the best fit for the data, and these factors were marked primarily by one or at most two personality disorder criteria sets. A series of regression analyses that used external validators tapping Axis I psychopathology, treatment for mental health problems, functioning scores, interpersonal conflict, and suicidal ideation and behavior provided support for the seven-factor solution. We discuss these findings in the context of previous studies that have examined the structure underlying the personality disorder criteria as well as the current proposals for DSM-5 personality disorders.

  17. Effective Synthesis of Nucleosides Utilizing O-Acetyl-Glycosyl Chlorides as Glycosyl Donors in the Absence of Catalyst: Mechanism Revision and Application to Silyl-Hilbert-Johnson Reaction.

    PubMed

    Liang, Chengyuan; Ju, Weihui; Ding, Shunjun; Sun, Han; Mao, Gennian

    2017-01-05

    An effective synthesis of nucleosides using glycosyl chlorides as glycosyl donors in the absence of Lewis acid has been developed. Glycosyl chlorides have been shown to be pivotal intermediates in the classical silyl-Hilbert-Johnson reaction. A possible mechanism that differs from the currently accepted mechanism advanced by Vorbrueggen has been proposed and verified by experiments. In practice, this catalyst-free method provides easy access to Capecitabine in high yield.

  18. Template Synthesis of Noble Metal Nanocrystals with Unusual Crystal Structures and Their Catalytic Applications.

    PubMed

    Fan, Zhanxi; Zhang, Hua

    2016-12-20

    Noble metal nanocrystals own high chemical stability, unique plasmonic and distinctive catalytic properties, making them outstanding in many applications. However, their practical applications are limited by their high cost and scarcity on the earth. One promising strategy to solve these problems is to boost their catalytic performance in order to reduce their usage amount. To realize this target, great research efforts have been devoted to the size-, composition-, shape- and/or architecture-controlled syntheses of noble metal nanocrystals during the past two decades. Impressively, recent experimental studies have revealed that the crystal structure of noble metal nanocrystals can also significantly affect their physicochemical properties, such as optical, magnetic, catalytic, mechanical, electrical and electronic properties. Therefore, besides the well-established size, composition, shape, and architecture control, the rise of crystal structure-controlled synthesis of noble metal nanocrystals will open up new opportunities to further improve their functional properties, and thus promote their potential applications in energy conversion, catalysis, biosensing, information storage, surface enhanced Raman scattering, waveguide, near-infrared photothermal therapy, controlled release, bioimaging, biomedicine, and so on. In this Account, we review the recent research progress on the crystal structure control of noble metal nanocrystals with a template synthetic approach and their crystal structure-dependent catalytic properties. We first describe the template synthetic methods, such as epitaxial growth and galvanic replacement reaction methods, in which a presynthesized noble metal nanocrystal with either new or common crystal structure is used as the template to direct the growth of unusual crystal structures of other noble metals. Significantly, the template synthetic strategy described here provides an efficient, simple and straightforward way to synthesize unusual

  19. Nonplanar aromatic compounds. 3. A proposed new strategy for the synthesis of Buckybowls. Synthesis, structure and reactions of

    PubMed

    Bodwell; Fleming; Mannion; Miller

    2000-08-25

    A new strategy for the synthesis of Buckybowls is presented and initial attempts to implement it are reported. This involves annulation of further rings onto polycyclic aromatic systems that prefer to be planar but have been "pre-bent" by the installation of a tether. Pyrenophane 2b reacts with TCNE and PTAD to give 1:1 and 1:2 adducts, respectively. The less strained pyrenophane 2c is unreactive toward TCNE but gives a 1:2 adduct with PTAD. Attempted electrophilic aromatic brominations of pyrenophane 2e under a variety of conditions were unsuccessful, as were attempts to brominate cyclophanediene 1c, the direct synthetic precursor of 2c. Tether cleavage and addition reactions occurred rather than substitution. In an effort to circumvent tether cleavage problems, [7]-, [8]- and [9](2,7)pyrenophanes 22b-d were prepared. However, attempted bromination and Friedel-Crafts acylations failed. Evidence for the fleeting existence of [6](2,7)pyrenophane 22a was also obtained. Comparison of structural data (X-ray and AM1 calculations) for the pyrenophanes 22a-d with their 1,n-dioxa analogues 2a-d indicates that the nature of the tether has a strong effect on the degree of bend in the pyrene moiety and this led to the identification of trioxapyrenophane 28 as the next target in the quest for increasingly bent pyrenes.

  20. Synthesis of cubic zirconium and hafnium nitride having Th3P4 structure.

    PubMed

    Zerr, Andreas; Miehe, Gerhard; Riedel, Ralf

    2003-03-01

    High-pressure synthesis is a powerful method for the preparation of novel materials with high elastic moduli and hardness. Additionally, such materials may exhibit interesting thermal, optoelectronic, semiconductuing, magnetic or superconducting properties. Here, we report on the high-pressure synthesis of zirconium and hafnium nitrides with the stoichiometry M3N4, where M = Zr, Hf. Synthesis experiments were performed in a laser-heated diamond anvil cell at pressures up to 18 GPa and temperatures up to 3,000 K. We observed formation of cubic Zr3N4 and Hf3N4 (c-M3N4) with a Th3P4-structure, where M-cations are eightfold coordinated by N anions. The c-M3N4 phases are the first binary nitrides with such a high coordination number. Both compounds exhibit high bulk moduli around 250 GPa, which indicates high hardness. Moreover, the new nitrides, c-Zr3N4 and c-Hf3N4, may be the first members of a larger group of transition metal and/or lanthanide nitrides with interesting ferromagnetic or superconducting behaviour.

  1. Total Synthesis of Chlorofusin, its Seven Chromophore Diastereomers, and Key Partial Structures

    PubMed Central

    Clark, Ryan C.; Lee, Sang Yeul; Boger, Dale L.

    2008-01-01

    Chlorofusin is a recently isolated, naturally occurring inhibitor of p53−MDM2 complex formation whose structure is composed of a densely functionalized azaphilone-derived chromophore linked through the terminal amine of ornithine to a nine residue cyclic peptide. Herein we report the full details of the total synthesis of chlorofusin, resulting in the assignment of the absolute stereochemistry and reassignment of the relative stereochemistry of the complex chromophore. Condensation of each enantiomer of an azaphilone chromophore precursor with the Nδ-amine of a protected ornithinethreonine dipeptide, followed by a one-step oxidation/spirocyclization of the most reactive olefin provided all eight diastereomers of the fully elaborated chromophore−dipeptide conjugate. Comparison of the spectroscopic properties for these eight compounds and those of simpler models with that reported for the natural product allowed the full assignment of the (4R,8S,9R)-stereochemistry of the chlorofusin chromophore. The natural, but stereochemically reassigned, diastereomer of the dipeptide conjugate was incorporated in a convergent total synthesis of chlorofusin confirming the stereochemical reassignment and establishing its absolute stereochemistry. Similarly and enlisting the late stage convergent point in the total synthesis, the remaining seven diastereomers of the chromophore−dipeptide conjugates were individually incorporated into the 9-residue cyclic peptide of chlorofusin (4 steps each) providing all seven remaining possible chromophore diastereomers of the natural product. PMID:18712872

  2. Heavy Grignard Reagents: Synthesis, Physical and Structural Properties, Chemical Behavior, and Reactivity.

    PubMed

    Westerhausen, Matthias; Koch, Alexander; Görls, Helmar; Krieck, Sven

    2017-01-31

    The Grignard reaction offers a straight forward atom-economic synthesis of organomagnesium halides, which undergo redistribution reactions (Schlenk equilibrium) yielding diorganylmagnesium and magnesium dihalides. The homologous organocalcium complexes (heavy Grignard reagents) gained interest only quite recently owing to several reasons. The discrepancy between the inertness of this heavy alkaline earth metal and the enormous reactivity of its organometallics hampered a vast and timely development after the first investigation more than 100 years ago. In this overview the synthesis of organocalcium reagents is described as is the durability in ethereal solvents. Aryl-, alkenyl-, and alkylcalcium halides are prepared by direct synthesis. Characteristic structural features and NMR parameters are discussed. Ligand redistribution reactions can be performed by addition of potassium tert-butanolate to ethereal solutions of arylcalcium iodides yielding soluble diarylcalcium, whereas sparingly soluble potassium iodide and calcium bis(tert-butanolate) precipitate. Furthermore, reactivity studies with respect to metalation and addition to unsaturated organic compounds and metal-based Lewis acids, leading to the formation of heterobimetallic complexes, are presented.

  3. Nickel hydroxides and related materials: a review of their structures, synthesis and properties

    PubMed Central

    Hall, David S.; Lockwood, David J.; Bock, Christina; MacDougall, Barry R.

    2015-01-01

    This review article summarizes the last few decades of research on nickel hydroxide, an important material in physics and chemistry, that has many applications in engineering including, significantly, batteries. First, the structures of the two known polymorphs, denoted as α-Ni(OH)2 and β-Ni(OH)2, are described. The various types of disorder, which are frequently present in nickel hydroxide materials, are discussed including hydration, stacking fault disorder, mechanical stresses and the incorporation of ionic impurities. Several related materials are discussed, including intercalated α-derivatives and basic nickel salts. Next, a number of methods to prepare, or synthesize, nickel hydroxides are summarized, including chemical precipitation, electrochemical precipitation, sol–gel synthesis, chemical ageing, hydrothermal and solvothermal synthesis, electrochemical oxidation, microwave-assisted synthesis, and sonochemical methods. Finally, the known physical properties of the nickel hydroxides are reviewed, including their magnetic, vibrational, optical, electrical and mechanical properties. The last section in this paper is intended to serve as a summary of both the potentially useful properties of these materials and the methods for the identification and characterization of ‘unknown’ nickel hydroxide-based samples. PMID:25663812

  4. Effect of Alcohol Structure on the Optimum Condition for Novozym 435-Catalyzed Synthesis of Adipate Esters

    PubMed Central

    Abdul Rahman, Mohd Basyaruddin; Chaibakhsh, Naz; Basri, Mahiran

    2011-01-01

    Immobilized Candida antarctica lipase B, Novozym 435, was used as the biocatalyst in the esterification of adipic acid with four different isomers of butanol (n-butanol, sec-butanol, iso-butanol, and tert-butanol). Optimum conditions for the synthesis of adipate esters were obtained using response surface methodology approach with a four-factor-five-level central composite design concerning important reaction parameters which include time, temperature, substrate molar ratio, and amount of enzyme. Reactions under optimized conditions has yielded a high percentage of esterification (>96%) for n-butanol, iso-butanol, and sec-butanol, indicating that extent of esterification is independent of the alcohol structure for primary and secondary alcohols at the optimum conditions. Minimum reaction time (135 min) for achieving maximum ester yield was obtained for iso-butanol. The required time for attaining maximum yield and also the initial rates in the synthesis of di-n-butyl and di-sec-butyl adipate were nearly the same. Immobilized Candida antarctica lipase B was also capable of esterifying tert-butanol with a maximum yield of 39.1%. The enzyme is highly efficient biocatalyst for the synthesis of adipate esters by offering a simple production process and a high esterification yield. PMID:22389769

  5. Metal-organic frameworks: structure, properties, methods of synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Butova, V. V.; Soldatov, M. A.; Guda, A. A.; Lomachenko, K. A.; Lamberti, C.

    2016-03-01

    This review deals with key methods of synthesis and characterization of metal-organic frameworks (MOFs). The modular structure affords a wide variety of MOFs with different active metal sites and organic linkers. These compounds represent a new stage of development of porous materials in which the pore size and the active site structure can be modified within wide limits. The set of experimental methods considered in this review is sufficient for studying the short-range and long-range order of the MOF crystal structure, determining the morphology of samples and elucidating the processes that occur at the active metal site in the course of chemical reactions. The interest in metal-organic frameworks results, first of all, from their numerous possible applications, ranging from gas separation and storage to chemical reactions within the pores. The bibliography includes 362 references.

  6. Discovery of a Structurally Unique Small Molecule that Inhibits Protein Synthesis

    PubMed Central

    Thakral, Durga; Tae, Hyun Seop

    2017-01-01

    Identifying and characterizing natural products and synthetic small molecules that inhibit biochemical processes such as ribosomal translation can lead to novel sources of molecular probes and therapeutics. The search for new antibiotics has been invigorated by the increasing burden of drug-resistant bacteria and has identified many clinically essential prokaryote-specific ribosome inhibitors. However, the current cohort of antibiotics is limited with regards to bacterial resistance mechanisms because of structural similarity within classes. From a high-throughput screen for translation inhibitors, we discovered a new compound, T6102, which inhibits bacterial protein synthesis in vitro, inhibits bacterial growth of Bacillus subtilis in vivo, and has a chemical structure that appears to be unique among known classes of translation-inhibiting antibiotics. T6102’s unique structure compared to current clinically-utilized antibiotics makes it an exciting new candidate for the development of next-generation antibiotics. PMID:28356892

  7. 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.

  8. Application of the Probabilistic Dynamic Synthesis Method to the Analysis of a Realistic Structure

    NASA Technical Reports Server (NTRS)

    Brown, Andrew M.; Ferri, Aldo A.

    1998-01-01

    The Probabilistic Dynamic Synthesis method is a new technique for obtaining the statistics of a desired response engineering quantity for a structure with non-deterministic parameters. The method uses measured data from modal testing of the structure as the input random variables, rather than more "primitive" quantities like geometry or material variation. This modal information is much more comprehensive and easily measured than the "primitive" information. The probabilistic analysis is carried out using either response surface reliability methods or Monte Carlo simulation. A previous work verified the feasibility of the PDS method on a simple seven degree-of-freedom spring-mass system. In this paper, extensive issues involved with applying the method to a realistic three-substructure system are examined, and free and forced response analyses are performed. The results from using the method are promising, especially when the lack of alternatives for obtaining quantitative output for probabilistic structures is considered.

  9. Synthesis, structure-activity relationship and crystallographic studies of 3-substituted indolin-2-one RET inhibitors.

    PubMed

    Mologni, Luca; Rostagno, Roberta; Brussolo, Stefania; Knowles, Phillip P; Kjaer, Svend; Murray-Rust, Judith; Rosso, Enrico; Zambon, Alfonso; Scapozza, Leonardo; McDonald, Neil Q; Lucchini, Vittorio; Gambacorti-Passerini, Carlo

    2010-02-15

    The synthesis, structure-activity relationships (SAR) and structural data of a series of indolin-2-one inhibitors of RET tyrosine kinase are described. These compounds were designed to explore the available space around the indolinone scaffold within RET active site. Several substitutions at different positions were tested and biochemical data were used to draw a molecular model of steric and electrostatic interactions, which can be applied to design more potent and selective RET inhibitors. The crystal structures of RET kinase domain in complex with three inhibitors were solved. All three compounds bound in the ATP pocket and formed two hydrogen bonds with the kinase hinge region. Crystallographic analysis confirmed predictions from molecular modelling and helped refine SAR results. These data provide important information for the development of indolinone inhibitors for the treatment of RET-driven cancers. Copyright 2010 Elsevier Ltd. All rights reserved.

  10. Mechanochemical Synthesis of Hydroxyapatite and Its Modifications: Composition, Structure, and Properties

    NASA Astrophysics Data System (ADS)

    Chaikina, M. V.; Bulina, N. V.; Ishchenko, A. V.; Prosanov, I. Yu.

    2014-02-01

    The mechanochemical method is used to synthesize samples of hydroxyapatite (HA) with substitution of the phosphate ion by silicate and zirconate ions, and substitution of calcium ions by copper ions. In the process of mechanochemical synthesis, carbonate ions and water molecules are incorporated into the structure of HA due to interaction of components of the reaction mixture with air. Intrusion of carbonate into the structure of HA is a competing process with modification of apatite by silicate and zirconate anions; therefore, the composition of the product during synthesis differs from the prescribed one. After annealing of the samples, the composition of the anion-modified HA can be described by the formula Са10(РО4)6- х (АО4) х (ОН)2- х , where (АО4)4- is the modifying anion. Substitution of calcium by copper ions localized at the Са1 position has been detected. Silver ions are not incorporated into the structure of HA, but are distributed in the apatite matrix in the form of nanocrystals of metallic silver.

  11. Synthesis, spectroscopic characterizations, crystal structures and DFT studies of nalidixic acid carbonyl hydrazones derivatives

    NASA Astrophysics Data System (ADS)

    Bergamini, F. R. G.; Ribeiro, M. A.; Lancellotti, M.; Machado, D.; Miranda, P. C. M. L.; Cuin, A.; Formiga, A. L. B.; Corbi, P. P.

    2016-09-01

    This article describes the synthesis and characterization of the 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazide (hzd) and six carbonyl hydrazones derivatives of the nalidixic with 1H-pyrrol-2-ylmethylidene (hpyrr), 1H-imidazol-2-ylmethylidene (h2imi), pyridin-2-ylmethylidene (h2py), pyridin-3-ylmethylidene (h3py), pyridin-4-ylmethylidene(h4py) and (2-hydroxyphenyl)methylidene (hsali). The carbonyl hydrazones were characterized by elemental and ESI-QTOF-MS analyses, IR and detailed NMR spectroscopic measurements. The 2D NMR experiments allowed the unambiguous assignment of the hydrogen, carbon and nitrogen atoms, which have not been reported for nalidixic acid carbonyl hydrazone derivatives so far. Crystal structures of hzd and the new carbonyl hydrazones h2imi, hpyrr and h3py were determined by X-ray diffraction studies. Although the synthesis of hzd was reported decades ago, the hzd crystal structure have not been reported yet. Geometric optimizations of all the characterized structures were performed with the aid of DFT studies. Despite the fact that the hydrazones with 2-pyridine carboxylic acid (h2py) and salicyl aldehyde (hsali) were already reported by literature, a detailed spectroscopic study followed by DFT studies are also reported for such compounds in this manuscript. Antimicrobial studies of the compounds are also presented.

  12. Total Synthesis, Assignment of the Relative and Absolute Stereochemistry, and Structural Reassignment of Phostriecin (aka Sultriecin)

    PubMed Central

    Burke, Christopher P.; Haq, Nadia; Boger, Dale L.

    2010-01-01

    A total synthesis of phostriecin (2) previously known as sultriecin (1), its structural reassignment as a phosphate versus sulfate monoester, and the assignment of its relative and absolute stereochemistry are disclosed herein. Key elements of the work, which provided first the originally assigned sulfate monoester 1 and then the reassigned and renamed phosphate monoester 2, relied on diagnostic 1H NMR spectroscopic properties of the natural product for the assignment of relative and absolute stereochemistry as well as the subsequent structural reassignment, and a convergent asymmetric total synthesis to provide the unequivocal authentic materials. Key steps of the synthetic approach include a Brown allylation for diastereoselective introduction of the C9 stereochemistry, an asymmetric CBS reduction to establish the lactone C5-stereochemistry, diastereoselective oxidative ring expansion of an α-hydroxyfuran to access the pyran lactone precursor, and single-step installation of the sensitive Z,Z,E-triene unit through a chelation-controlled cuprate addition with installation of the C11 stereochemistry. The approach allows ready access to analogues that can now be used to probe important structural features required for PP2A inhibition, the mechanism of action defined herein. PMID:20108904

  13. Total synthesis, assignment of the relative and absolute stereochemistry, and structural reassignment of phostriecin (aka Sultriecin).

    PubMed

    Burke, Christopher P; Haq, Nadia; Boger, Dale L

    2010-02-24

    A total synthesis of phostriecin (2), previously known as sultriecin (1), its structural reassignment as a phosphate versus sulfate monoester, and the assignment of its relative and absolute stereochemistry are disclosed herein. Key elements of the work, which provided first the originally assigned sulfate monoester 1 and then the reassigned and renamed phosphate monoester 2, relied on diagnostic (1)H NMR spectroscopic properties of the natural product for the assignment of relative and absolute stereochemistry as well as the subsequent structural reassignment, and a convergent asymmetric total synthesis to provide the unequivocal authentic materials. Key steps of the synthetic approach include a Brown allylation for diastereoselective introduction of the C9 stereochemistry, an asymmetric CBS reduction to establish the lactone C5-stereochemistry, diastereoselective oxidative ring expansion of an alpha-hydroxyfuran to access the pyran lactone precursor, and single-step installation of the sensitive Z,Z,E-triene unit through a chelation-controlled cuprate addition with installation of the C11 stereochemistry. The approach allows ready access to analogues that can now be used to probe important structural features required for protein phosphatase 2A inhibition, the mechanism of action defined herein.

  14. Synthesis and NMR structure of p41icf, a potent inhibitor of human cathepsin L.

    PubMed

    Chiva, Cristina; Barthe, Philippe; Codina, Anna; Gairí, Margarida; Molina, Franck; Granier, Claude; Pugnière, Martine; Inui, Tatsuya; Nishio, Hideki; Nishiuchi, Yuji; Kimura, Terutoshi; Sakakibara, Shumpei; Albericio, Fernando; Giralt, Ernest

    2003-02-12

    The total synthesis and structural characterization of the MHCII-associated p41 invariant chain fragment (P41icf) is described. P41icf plays a crucial role in the maturation of MHC class II molecules and antigen processing, acting as a highly selective cathepsin L inhibitor. P41icf synthesis was achieved using a combined solid-phase/solution approach. The entire molecule (65 residues, 7246 Da unprotected) was assembled in solution from fully protected peptides in the size range of 10 residues. After deprotection, oxidative folding in carefully adjusted experimental conditions led to the completely folded and functional P41icf with a disulfide pairing identical to that of native P41icf. CD, NMR, and surface plasmon resonance (SPR) were used for the structural and functional characterization of synthetic P41icf. CD thermal denaturation showed clear cooperative behavior. Tight cathepsin L binding was demonstrated by SPR. (1)H NMR spectroscopy at 800 MHz of unlabeled P41icf was used to solve the three-dimensional structure of the molecule. P41icf behaves as a well-folded protein domain with a topology very close to the crystallographic cathepsin L-bound form.

  15. Simple synthesis, structure and ab initio study of 1,4-benzodiazepine-2,5-diones

    NASA Astrophysics Data System (ADS)

    Jadidi, Khosrow; Aryan, Reza; Mehrdad, Morteza; Lügger, Thomas; Ekkehardt Hahn, F.; Ng, Seik Weng

    2004-04-01

    A simple procedure for the synthesis of pyrido[2,1-c][1,4] benzodiazepine-6,12-dione ( 1) and 1,4-benzodiazepine-2,5-diones ( 2a- 2d), using microwave irradiation and/or conventional heating is reported. The configuration of 1 was determined by single-crystal X-ray diffraction. A detailed ab initio B3LYP/6-31G* calculation of structural parameters and substituent effects on ring inversion barriers (Δ G#) and also free energy differences (Δ G0) for benzodiazepines are reported.

  16. 2-Pyridyl thiazoles as novel anti-Trypanosoma cruzi agents: structural design, synthesis and pharmacological evaluation.

    PubMed

    Cardoso, Marcos Veríssimo de Oliveira; de Siqueira, Lucianna Rabelo Pessoa; da Silva, Elany Barbosa; Costa, Lívia Bandeira; Hernandes, Marcelo Zaldini; Rabello, Marcelo Montenegro; Ferreira, Rafaela Salgado; da Cruz, Luana Faria; Moreira, Diogo Rodrigo Magalhães; Pereira, Valéria Rêgo Alves; de Castro, Maria Carolina Accioly Brelaz; Bernhardt, Paul V; Leite, Ana Cristina Lima

    2014-10-30

    The present work reports on the synthesis, anti-Trypanosoma cruzi activities and docking studies of a novel series of 2-(pyridin-2-yl)-1,3-thiazoles derived from 2-pyridine thiosemicarbazone. The majority of these compounds are potent cruzain inhibitors and showed excellent inhibition on the trypomastigote form of the parasite, and the resulting structure-activity relationships are discussed. Together, these data present a novel series of thiazolyl hydrazones with potential effects against Chagas disease and they could be important leads in continuing development against Chagas disease. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  17. Choosing Sensor Configuration for a Flexible Structure Using Full Control Synthesis

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Nalbantoglu, Volkan; Balas, Gary

    1997-01-01

    Optimal locations and types for feedback sensors which meet design constraints and control requirements are difficult to determine. This paper introduces an approach to choosing a sensor configuration based on Full Control synthesis. A globally optimal Full Control compensator is computed for each member of a set of sensor configurations which are feasible for the plant. The sensor configuration associated with the Full Control system achieving the best closed-loop performance is chosen for feedback measurements to an output feedback controller. A flexible structure is used as an example to demonstrate this procedure. Experimental results show sensor configurations chosen to optimize the Full Control performance are effective for output feedback controllers.

  18. Structural organization of films based on polyaniline/polysulfonic acid complexes depending on the synthesis method

    SciTech Connect

    Simagina, L. V. Gaynutdinov, R. V.; Stepina, N. D.; Sorokina, K. L.; Morozova, O. V.; Shumakovich, G. P.; Yaropolov, A. I.; Tolstikhina, A. L.

    2010-07-15

    The optical properties and morphology of complexes based on polyaniline (PANI) and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS), depending on their synthesis conditions, have been characterized by UV-visible spectroscopy and atomic force microscopy. The dependence of the electron absorption spectra of PANI/PAMPS complexes and the surface topography of their films on the initiation way of PANI formation (chemical and enzymatic) and the use of promoters of aniline polymerization has been investigated. The aniline polymerization kinetics with and without polymerization promoters has been studied. All PANI/PAMPS complexes are found to have a nanocomposite time-stable structure.

  19. Synthesis and characterization of high temperature curable poly(arylene ether) structural adhesive and composite matrices

    SciTech Connect

    Mecham, S.J.; Jayaraman, S.; Bobbitt, M.M.

    1996-12-31

    Crosslinked poly(arylene ether) systems are projected to display many desirable properties suitable for aerospace structural adhesive and composite matrix applications. The synthesis and characterization of a series of processable high temperature curing poly(arylene ether) oligomers incorporating terminally reactive phenylethynyl endgroups will be discussed. Characterization of the oligomers includes NMR, intrinsic viscosity, parallel plate rheological behavior, TGA, and DSC. Curing of these oligomers was conducted at or above 380{degrees}C, providing a large processing window. Thermal stability is very good and the melt viscosity of the oligomers in the processing temperature range is exceptionally low.

  20. Synthesis, crystal structures and spectral characterization of chiral 4-R-1,2,4-triazoles

    NASA Astrophysics Data System (ADS)

    Gural'skiy, Il'ya A.; Reshetnikov, Viktor A.; Omelchenko, Irina V.; Szebesczyk, Agnieszka; Gumienna-Kontecka, Elzbieta; Fritsky, Igor O.

    2017-01-01

    1,2,4-triazoles attract attention as actively used medications and ligands for constructing coordination architectures. In this paper we describe four optically active 4-substituted 1,2,4-triazoles that have been prepared by Bayer's synthesis from the corresponding aliphatic chiral amines. This approach tends to be universal towards different triazoles and permits to conserve a homochirality of substrates. Novel asymmetric molecules have been characterized by spectroscopic techniques and their structures have been retrieved from the single crystal X-ray analysis. Chiro-optical studies of these heterocycles have been made by means of circular dichroism spectroscopy.

  1. Cell-free protein synthesis for structure determination by X-ray crystallography.

    PubMed

    Watanabe, Miki; Miyazono, Ken-ichi; Tanokura, Masaru; Sawasaki, Tatsuya; Endo, Yaeta; Kobayashi, Ichizo

    2010-01-01

    Structure determination has been difficult for those proteins that are toxic to the cells and cannot be prepared in a large amount in vivo. These proteins, even when biologically very interesting, tend to be left uncharacterized in the structural genomics projects. Their cell-free synthesis can bypass the toxicity problem. Among the various cell-free systems, the wheat-germ-based system is of special interest due to the following points: (1) Because the gene is placed under a plant translational signal, its toxic expression in a bacterial host is reduced. (2) It has only little codon preference and, especially, little discrimination between methionine and selenomethionine (SeMet), which allows easy preparation of selenomethionylated proteins for crystal structure determination by SAD and MAD methods. (3) Translation is uncoupled from transcription, so that the toxicity of the translation product on DNA and its transcription, if any, can be bypassed. We have shown that the wheat-germ-based cell-free protein synthesis is useful for X-ray crystallography of one of the 4-bp cutter restriction enzymes, which are expected to be very toxic to all forms of cells retaining the genome. Our report on its structure represents the first report of structure determination by X-ray crystallography using protein overexpressed with the wheat-germ-based cell-free protein expression system. This will be a method of choice for cytotoxic proteins when its cost is not a problem. Its use will become popular when the crystal structure determination technology has evolved to require only a tiny amount of protein.

  2. The Anxiety Sensitivity Index--Revised: confirmatory factor analyses, structural invariance in Caucasian and African American samples, and score reliability and validity.

    PubMed

    Arnau, Randolph C; Broman-Fulks, Joshua J; Green, Bradley A; Berman, Mitchell E

    2009-06-01

    The most commonly used measure of anxiety sensitivity is the 36-item Anxiety Sensitivity Index-Revised (ASI-R). Exploratory factor analyses have produced several different factors structures for the ASI-R, but an acceptable fit using confirmatory factor analytic approaches has only been found for a 21-item version of the instrument. We evaluated the fit of all published factor models for the 36- and 21-item ASI-R, modified the hierarchical model using an approach that does not eliminate items, evaluated the invariance of the modified model across Caucasian and African-American subsamples, and compared the reliability and validity of the 36-item and 21-item versions. The 21-item version of the ASI-R fit a four factor model, as did the 36-item version after several meaningful model modifications. The modified 36-item model was replicable in independent cases and its structural properties were generally invariant across race. Scores from the 36-item version exhibited superior reliability and criterion-related validity.

  3. Epothilones as lead structures for the synthesis-based discovery of new chemotypes for microtubule stabilization.

    PubMed

    Feyen, Fabian; Cachoux, Frédéric; Gertsch, Jürg; Wartmann, Markus; Altmann, Karl-Heinz

    2008-01-01

    Epothilones are macrocyclic bacterial natural products with potent microtubule-stabilizing and antiproliferative activity. They have served as successful lead structures for the development of several clinical candidates for anticancer therapy. However, the structural diversity of this group of clinical compounds is rather limited, as their structures show little divergence from the original natural product leads. Our own research has explored the question of whether epothilones can serve as a basis for the development of new structural scaffolds, or chemotypes, for microtubule stabilization that might serve as a basis for the discovery of new generations of anticancer drugs. We have elaborated a series of epothilone-derived macrolactones whose overall structural features significantly deviate from those of the natural epothilone scaffold and thus define new structural families of microtubule-stabilizing agents. Key elements of our hypermodification strategy are the change of the natural epoxide geometry from cis to trans, the incorporation of a conformationally constrained side chain, the removal of the C3-hydroxyl group, and the replacement of C12 with nitrogen. So far, this approach has yielded analogs 30 and 40 that are the most advanced, the most rigorously modified, structures, both of which are potent antiproliferative agents with low nanomolar activity against several human cancer cell lines in vitro. The synthesis was achieved through a macrolactone-based strategy or a high-yielding RCM reaction. The 12-aza-epothilone ("azathilone" 40) may be considered a "non-natural" natural product that still retains most of the overall structural characteristics of a true natural product but is structurally unique, because it lies outside of the general scope of Nature's biosynthetic machinery for polyketide synthesis. Like natural epothilones, both 30 and 40 promote tubulin polymerization in vitro and at the cellular level induce cell cycle arrest in mitosis. These

  4. Mesoporous silicas with covalently immobilized β-cyclodextrin moieties: synthesis, structure, and sorption properties

    NASA Astrophysics Data System (ADS)

    Roik, Nadiia V.; Belyakova, Lyudmila A.; Trofymchuk, Iryna M.; Dziazko, Marina O.; Oranska, Olena I.

    2017-09-01

    Mesoporous silicas with chemically attached macrocyclic moieties were successfully prepared by sol-gel condensation of tetraethyl orthosilicate and β-cyclodextrin-silane in the presence of a structure-directing agent. Introduction of β-cyclodextrin groups into the silica framework was confirmed by the results of IR spectral, thermogravimetric, and quantitative chemical analysis of surface compounds. The porous structure of the obtained materials was characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction, transmission electron microscopy, and dynamic light scattering. It was found that the composition of the reaction mixture used in β-cyclodextrin-silane synthesis significantly affects the structural parameters of the resulting silicas. The increase in (3-aminopropyl)triethoxysilane as well as the coupling agent content in relation to β-cyclodextrin leads ultimately to the lowering or complete loss of hexagonal arrangement of pore channels in the synthesized materials. Formation of hexagonally ordered mesoporous structure was observed at molar composition of the mixture 0.049 TEOS:0.001 β-CD-silane:0.007 CTMAB:0.27 NH4OH:7.2 H2O and equimolar ratio of components in β-CD-silane synthesis. The sorption of alizarin yellow on starting silica and synthesized materials with chemically attached β-cyclodextrin moieties was studied in phosphate buffer solutions with pH 7.0. Experimental results of the dye equilibrium sorption were analyzed using Langmuir, Freundlich, and Redlich-Peterson isotherm models. It was proved that the Redlich-Peterson isotherm model is the most appropriate for fitting the equilibrium sorption of alizarin yellow on parent silica with hexagonally arranged mesoporous structure as well as on modified one with chemically immobilized β-cyclodextrin groups. [Figure not available: see fulltext.

  5. Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

    NASA Astrophysics Data System (ADS)

    Caskey, Christopher M.; Holder, Aaron; Shulda, Sarah; Christensen, Steven T.; Diercks, David; Schwartz, Craig P.; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S.; Tumas, William; Perkins, John D.; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M.; Zakutayev, Andriy

    2016-04-01

    Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.

  6. Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

    SciTech Connect

    Caskey, Christopher M.; Holder, Aaron; Shulda, Sarah; Christensen, Steven T.; Diercks, David; Schwartz, Craig P.; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S.; Tumas, William; Perkins, John D.; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M.; Zakutayev, Andriy

    2016-04-12

    Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. Furthermore, this observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.

  7. Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

    DOE PAGES

    Caskey, Christopher M.; Holder, Aaron; Shulda, Sarah; ...

    2016-04-12

    Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experimentsmore » indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. Furthermore, this observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.« less

  8. Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures.

    PubMed

    Caskey, Christopher M; Holder, Aaron; Shulda, Sarah; Christensen, Steven T; Diercks, David; Schwartz, Craig P; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S; Tumas, William; Perkins, John D; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M; Zakutayev, Andriy

    2016-04-14

    Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.

  9. Synthesis and Crystal Structure Study of 2’-Se-Adenosine-Derivatized DNA

    SciTech Connect

    Sheng, J.; Salon, J; Gan, J; Huang, Z

    2010-01-01

    The selenium derivatization of nucleic acids is a novel and promising strategy for 3D structure determination of nucleic acids. Selenium can serve as an excellent anomalous scattering center to solve the phase problem, which is one of the two major bottlenecks in macromolecule X-ray crystallography. The other major bottleneck is crystallization. It has been demonstrated that the incorporated selenium functionality at the 2'-positions of the nucleosides and nucleotides is stable and does not cause significant structure perturbation. Furthermore, it was observed that the 2'-Se-derivatization could facilitate crystallization of oligonucleotides with fast crystal growth and high diffraction quality. Herein, we describe a convenient synthesis of the 2'-Se-adenosine phosphoramidite, and report the first synthesis and X-ray crystal structure determination of the DNA containing the 2'-Se-A derivatization. The 3D structure of 2'-Se-A-DNA decamer [5'-GTACGCGT(2'-Se-A)C-3']{sub 2} was determined at 1.75 {angstrom} resolution, the 2'-Se-functionality points to the minor groove, and the Se-modified and native structures are virtually identical. Moreover, we have observed that the 2'-Se-A modification can greatly facilitate the crystal growth with high diffraction quality. In conjunction with the crystallization facilitation by the 2'-Se-U and 2'-Se-T, this novel observation on the 2'-Se-A functionality suggests that the 2'-Se moiety is sole responsible for the crystallization facilitation and the identity of nucleobases does not influence the crystal growth significantly.

  10. Controllable synthesis of branched ZnO/Si nanowire arrays with hierarchical structure

    PubMed Central

    2014-01-01

    A rational approach for creating branched ZnO/Si nanowire arrays with hierarchical structure was developed based on a combination of three simple and cost-effective synthesis pathways. The crucial procedure included growth of crystalline Si nanowire arrays as backbones by chemical etching of Si substrates, deposition of ZnO thin film as a seed layer by magnetron sputtering, and fabrication of ZnO nanowire arrays as branches by hydrothermal growth. The successful synthesis of ZnO/Si heterogeneous nanostructures was confirmed by morphologic, structural, and optical characterizations. The roles of key experimental parameters, such as the etchant solution, the substrate direction, and the seed layer on the hierarchical nanostructure formation, were systematically investigated. It was demonstrated that an etchant solution with an appropriate redox potential of the oxidant was crucial for a moderate etching speed to achieve a well-aligned Si nanowire array with solid and round surface. Meanwhile, the presence of gravity gradient was a key issue for the growth of branched ZnO nanowire arrays. The substrate should be placed vertically or facedown in contrast to the solution surface during the hydrothermal growth. Otherwise, only the condensation of the ZnO nanoparticles took place in a form of film on the substrate surface. The seed layer played another important role in the growth of ZnO nanowire arrays, as it provided nucleation sites and determined the growing direction and density of the nanowire arrays for reducing the thermodynamic barrier. The results of this study might provide insight on the synthesis of hierarchical three-dimensional nanostructure materials and offer an approach for the development of complex devices and advanced applications. PMID:25024688

  11. Synthesis of 7-Epineoptilocaulin, Mirabilin B, and Isoptilocaulin. A Unified Biosynthetic Proposal for the Ptilocaulin and Batzelladine Alkaloids. Synthesis and Structure Revision of Netamines E and G

    PubMed Central

    Yu, Min; Pochapsky, Susan S.; Snider, Barry B.

    2008-01-01

    Addition of guanidine to a 6-methylhexahydroindenone in MeOH at reflux afforded 7-epineoptilocaulin. A similar reaction with a 6-propylhexahydroindenone afforded netamine E. MnO2 oxidation of 7-epineoptilocaulin and netamine E afforded mirabilin B and netamine G, respectively. The netamines have the side chains trans, not cis as was initially proposed. A unified biosynthetic scheme for the batzelladines and ptilocaulin family is proposed. Conjugate addition of guanidine to a bis enone followed by an intramolecular Michael reaction of the enolate to the other enone, aldol reaction, dehydration and enamine formation will lead to a tricyclic intermediate at the dehydroptilocaulin oxidation state. 1,4-Hydride addition will lead to ptilocaulin or 7-epineoptilocaulin depending on which face the hydride adds to. 1,2-Hydride addition will lead to isoptilocaulin. The key tricyclic intermediate was prepared from a tetrahydroindenone and guanidine and reduced with NaBH4 to give a mixture rich in ptilocaulin and isoptilocaulin. PMID:18928319

  12. New and Improved? A Comparison of the Original and Revised Versions of the Structured Interview of Reported Symptoms

    ERIC Educational Resources Information Center

    Green, Debbie; Rosenfeld, Barry; Belfi, Brian

    2013-01-01

    The current study evaluated the accuracy of the Structured Interview of Reported Symptoms, Second Edition (SIRS-2) in a criterion-group study using a sample of forensic psychiatric patients and a community simulation sample, comparing it to the original SIRS and to results published in the SIRS-2 manual. The SIRS-2 yielded an impressive…

  13. New and Improved? A Comparison of the Original and Revised Versions of the Structured Interview of Reported Symptoms

    ERIC Educational Resources Information Center

    Green, Debbie; Rosenfeld, Barry; Belfi, Brian

    2013-01-01

    The current study evaluated the accuracy of the Structured Interview of Reported Symptoms, Second Edition (SIRS-2) in a criterion-group study using a sample of forensic psychiatric patients and a community simulation sample, comparing it to the original SIRS and to results published in the SIRS-2 manual. The SIRS-2 yielded an impressive…

  14. Synthesis of magnesium- and manganese-doped hydroxyapatite structures assisted by the simultaneous incorporation of strontium.

    PubMed

    Moreira, Mirna Pereira; de Almeida Soares, Gloria Dulce; Dentzer, Joseph; Anselme, Karine; de Sena, Lídia Ágata; Kuznetsov, Alexei; dos Santos, Euler Araujo

    2016-04-01

    Samples of crystalline hydroxyapatite (HA) with and without the addition of individual Mg(2+), Mn(2+) and Sr(2+) ions and samples with the addition of all three ions simultaneously were prepared using the precipitation method in an aqueous medium. Chemical, structural, spectroscopic and thermophysical analyses of the synthesized samples were conducted. The obtained results indicate that Sr(2+) ions were easily incorporated into the HA crystal structure, whereas it was difficult to incorporate Mg(2+) and Mn(2+) ions into the HA lattice when these ions were individually introduced into the samples. The synthesis of HA with Mg(2+) or Mn(2+) ions is characterized by the formation of HA with a low concentration of doping elements that is outweighed by the amount of these atoms present in less biocompatible phases that formed simultaneously. However, the incorporation of Sr(2+) along with Mg(2+) and Mn(2+) ions into the samples allowed for the synthesis of HA with considerably higher concentrations of Mg(2+) and Mn(2+) in the crystal lattice.

  15. Structural and Mechanistic Insight into the Listeria monocytogenes Two-enzyme Lipoteichoic Acid Synthesis System*

    PubMed Central

    Campeotto, Ivan; Percy, Matthew G.; MacDonald, James T.; Förster, Andreas; Freemont, Paul S.; Gründling, Angelika

    2014-01-01

    Lipoteichoic acid (LTA) is an important cell wall component required for proper cell growth in many Gram-positive bacteria. In Listeria monocytogenes, two enzymes are required for the synthesis of this polyglycerolphosphate polymer. The LTA primase LtaPLm initiates LTA synthesis by transferring the first glycerolphosphate (GroP) subunit onto the glycolipid anchor and the LTA synthase LtaSLm extends the polymer by the repeated addition of GroP subunits to the tip of the growing chain. Here, we present the crystal structures of the enzymatic domains of LtaPLm and LtaSLm. Although the enzymes share the same fold, substantial differences in the cavity of the catalytic site and surface charge distribution contribute to enzyme specialization. The eLtaSLm structure was also determined in complex with GroP revealing a second GroP binding site. Mutational analysis confirmed an essential function for this binding site and allowed us to propose a model for the binding of the growing chain. PMID:25128528

  16. Controlled synthesis of organic nanophotonic materials with specific structures and compositions.

    PubMed

    Cui, Qiu Hong; Zhao, Yong Sheng; Yao, Jiannian

    2014-10-29

    Organic nanomaterials have drawn great interest for their potential applications in high-speed miniaturized photonic integration due to their high photoluminescence quantum efficiency, structural processability, ultrafast photoresponse, and excellent property engineering. Based on the rational design on morphological and componential levels, a series of organic nanomaterials have been controllably synthesized in recent years, and their excitonic/photonic behaviors has been fine-tuned to steer the light flow for specific optical applications. This review presents a comprehensive summary of recent breakthroughs in the controlled synthesis of organic nanomaterials with specific structures and compositions, whose tunable photonic properties would provide a novel platform for multifunctional applications. First, we give a general overview of the tailored construction of novel nanostructures with various photonic properties. Then, we summarize the design and controllable synthesis of composite materials for the modulation of their functionalities. Subsequently, special emphasis is put on the fabrication of complex nanostructures towards wide applications in isolated photonic devices. We conclude with our personal viewpoints on the development directions in the novel design and controllable construction of organic nanomaterials for future applications in highly integrated photonic devices and chips.

  17. Total synthesis and structure-activity relationship studies of a series of selective G protein inhibitors

    NASA Astrophysics Data System (ADS)

    Xiong, Xiao-Feng; Zhang, Hang; Underwood, Christina R.; Harpsøe, Kasper; Gardella, Thomas J.; Wöldike, Mie F.; Mannstadt, Michael; Gloriam, David E.; Bräuner-Osborne, Hans; Strømgaard, Kristian

    2016-11-01

    G proteins are key mediators of G protein-coupled receptor signalling, which facilitates a plethora of important physiological processes. The cyclic depsipeptides YM-254890 and FR900359 are the only known specific inhibitors of the Gq subfamily of G proteins; however, no synthetic route has been reported previously for these complex natural products and they are not easily isolated from natural sources. Here we report the first total synthesis of YM-254890 and FR900359, as well as of two known analogues, YM-385780 and YM-385781. The versatility of the synthetic approach also enabled the design and synthesis of ten analogues, which provided the first structure-activity relationship study for this class of compounds. Pharmacological characterization of all the compounds at Gq-, Gi- and Gs-mediated signalling provided succinct information on the structural requirements for inhibition, and demonstrated that both YM-254890 and FR900359 are highly potent inhibitors of Gq signalling, with FR900359 being the most potent. These natural products and their analogues represent unique tools for explorative studies of G protein inhibition.

  18. Synthesis of TiO 2 nanostructured reservoir with temozolomide: Structural evolution of the occluded drug

    NASA Astrophysics Data System (ADS)

    López, T.; Sotelo, J.; Navarrete, J.; Ascencio, J. A.

    2006-10-01

    Sol-gel synthesized nanostructured TiO 2 matrix were produced with different channel sizes, where drug are immersed, producing a reservoir with Temozolomide (TMZ). This drug is particularly important for the treatment of cancer tumors, which are fundamentally a consequence of the uncontrolled reproduction of human cell. In this way the chemotherapy plays an important role in the treatment of both recurrent and newly diagnosed patients. In the handling of brain tumors TMZ has been discovered as a recent and efficient second generation drug employed in the control of advanced brain gliomas, and it is a welcome addition. Its active component binds to the cancerous DNA cells, thus preventing their disordered growth, destroying them. In this work, we report the synthesis of TiO 2 nanostructured reservoir with TMZ, focusing the effort to the understanding of structural effects on the TMZ configuration by using nuclear magnetic resonance, Raman and IR spectroscopy methods. Our results establish that TMZ molecules are quite sensible to chemical processes and it produces the activation of the molecule, which is followed and understood with help of quantum molecular simulation methods. The study of the molecules allows determining the conditions that produce the activation and chemical selectivity of the molecules, which determines the conditions of synthesis. This information gives parameters for the reservoir structural and chemical optimization.

  19. Fischer-Tropsch synthesis on hierarchically structured cobalt nanoparticle/carbon nanofiber/carbon felt composites.

    PubMed

    Zarubova, Sarka; Rane, Shreyas; Yang, Jia; Yu, Yingda; Zhu, Ye; Chen, De; Holmen, Anders

    2011-07-18

    The hierarchically structured carbon nanofibers (CNFs)/carbon felt composites, in which CNFs were directly grown on the surface of microfibers in carbon felt, forming a CNF layer on a micrometer range that completely covers the microfiber surfaces, were tested as a novel support material for cobalt nanoparticles in the highly exothermic Fischer-Tropsch (F-T) synthesis. A compact, fixed-bed reactor, made of disks of such composite materials, offered the advantages of improved heat and mass transfer, relatively low pressure drop, and safe handling of immobilized CNFs. An efficient 3-D thermal conductive network in the composite provided a relatively uniform temperature profile, whereas the open structure of the CNF layer afforded an almost 100 % effectiveness of Co nanoparticles in the F-T synthesis in the fixed bed. The greatly improved mass and heat transport makes the compact reactor attractive for applications in the conversion of biomass, coal, and natural gas to liquids. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Asymmetric Synthesis of Sesaminone: Confirmation of Its Structure and Determination of Its Absolute Configuration.

    PubMed

    Maioli, Andrew T.; Civiello, Rita L.; Foxman BM and, Bruce M.; Gordon, Dana M.

    1997-10-17

    An asymmetric synthesis of the naturally occurring antipode of the tetrahydrofuran lignan sesaminone ((-)-1) has been achieved. An X-ray crystal structure of the synthetic material validated the structure proposed in the literature for this lignan. Additionally, the absolute configuration of the natural product was established by correlation of the synthetic tetrahydrofuran with the known absolute configuration of L-Phe. The opening of the synthesis was a diastereoselective Evans aldol reaction between N-4-pentenoyloxazolidinone 6 and piperonal. Reduction of the major diastereomer of the aldol product provided enantiomerically pure diol 4. The primary and secondary hydroxyl groups of 4 were protected in tandem to generate silyl ether-MOM ether 9. The vinyl group contained in 9 was then elaborated, via a series of four steps, to aryl ketone 10. This aryl ketone was transformed to a mixture of silyl enol ether stereoisomers (11a,b); TiCl(4)-mediated activation of the MOM ethers contained in this mixture of enol ethers yielded tetrahydrofuran 12 as the major product. Treatment of 12 with fluoride provided synthetic (-)-1.