WorldWideScience

Sample records for all-carbon quaternary stereogenic

  1. Stereocontrolled Introduction of the Quaternary Stereogenic Centre in Lyngbyatoxin A

    DEFF Research Database (Denmark)

    Tønder, Janne Ejrnæs; Tanner, David Ackland

    In our study of the enantioselective total synthesis of Lyngbyatoxin A, we have focused first on the stereocontrolled introduction of the quaternary stereogenic centre. The key step in the synthesis involves an enantiospecific Lewis-acid mediated rearrangement of chiral vinyl epoxides, a methodol......In our study of the enantioselective total synthesis of Lyngbyatoxin A, we have focused first on the stereocontrolled introduction of the quaternary stereogenic centre. The key step in the synthesis involves an enantiospecific Lewis-acid mediated rearrangement of chiral vinyl epoxides, a...... methodology developed by Jung et al(1). For model studies, the requisite vinyl epoxides were obtained by Sharpless asymmetric epoxidation of the corresponding allylic alcohols, followed by a TPAP oxidation and a Wittig reaction. It was observed that the choice of protective group on the indole nitrogen in had...... from hydrogen and indole migration respectively, in a 3:2 relationship; the desired aldehyde was thus the minor product. In order to benefit from the regioselectivity of the benzyl protected indole, we synthesised the isomeric vinyl epoxide. To our satisfaction the only product from the rearrangement...

  2. Toward the Enantioselective Total Synthesis of Lyngbyatoxin A: On the Stereocontrolled Introduction of the Quaternary Stereogenic Centre

    DEFF Research Database (Denmark)

    Tønder, Janne Ejrnæs; Tanner, David Ackland

    2003-01-01

    This paper deals with an approach to the enantioselective total synthesis of Lyngbyatoxin A, with focus on the stereocontrolled introduction of the quaternary stereogenic centre. The key step in the synthesis involves an enantiospecific Lewis-acid mediated rearrangement of chiral vinyl epoxides...

  3. Enantioselective construction of quaternary stereogenic carbons by the Lewis base catalyzed additions of silyl ketene imines to aldehydes.

    Science.gov (United States)

    Denmark, Scott E; Wilson, Tyler W; Burk, Matthew T; Heemstra, John R

    2007-12-01

    Silyl ketene imines derived from a variety of alpha-branched nitriles have been developed as highly useful reagents for the construction of quaternary stereogenic centers via the aldol addition reaction. In the presence of SiCl4 and the catalytic action of chiral phosphoramide (R,R)-5, silyl ketene imines undergo extremely rapid and high yielding addition to a wide variety of aromatic aldehydes with excellent diastereo- and enantioselectivity. Of particular note is the high yields and selectivities obtained from electron-rich, electron-poor, and hindered aldehydes. The nitrile function serves as a useful precursor for further synthetic manipulation. PMID:17988135

  4. Construction of quaternary stereogenic carbon centers through copper-catalyzed enantioselective allylic cross-coupling with alkylboranes.

    Science.gov (United States)

    Hojoh, Kentaro; Shido, Yoshinori; Ohmiya, Hirohisa; Sawamura, Masaya

    2014-05-01

    A combination of an in situ generated chiral Cu(I) /DTBM-MeO-BIPHEP catalyst system and EtOK enabled the enantioselective SN 2'-type allylic cross-coupling between alkylborane reagents and γ,γ-disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp(3) -alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross-coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed. PMID:24668885

  5. Redox-Triggered C–C Coupling of Alcohols and Vinyl Epoxides: Diastereo- and Enantioselective Formation of All-Carbon Quaternary Centers via tert-(Hydroxy)-Prenylation

    OpenAIRE

    Feng, Jiajie; Garza, Victoria J.; Krische, Michael J.

    2014-01-01

    Iridium catalyzed primary alcohol oxidation triggers reductive C–O bond cleavage of isoprene oxide to form aldehyde-allyliridium pairs that combine to form products of tert-(hydroxy)-prenylation, a motif found in >2000 terpenoid natural products. Curtin–Hammett effects are exploited to enforce high levels of anti-diastereo- and enantioselectivity in the formation of an all-carbon quaternary center. The present redox-triggered carbonyl additions occur in the absence of stoichiometric byproduct...

  6. Palladium-catalyzed asymmetric alkylation in the synthesis of cyclopentanoid and cycloheptanoid core structures bearing all-carbon quaternary stereocenters

    KAUST Repository

    Hong, Allen Y.

    2011-12-01

    General catalytic asymmetric routes toward cyclopentanoid and cycloheptanoid core structures embedded in numerous natural products have been developed. The central stereoselective transformation in our divergent strategies is the enantioselective decarboxylative alkylation of seven-membered β-ketoesters to form α-quaternary vinylogous esters. Recognition of the unusual reactivity of β-hydroxyketones resulting from the addition of hydride or organometallic reagents enabled divergent access to γ-quaternary acylcyclopentenes through a ring contraction pathway or γ-quaternary cycloheptenones through a carbonyl transposition pathway. Synthetic applications of these compounds were explored through the preparation of mono-, bi-, and tricyclic derivatives that can serve as valuable intermediates for the total synthesis of complex natural products. This work complements our previous work with cyclohexanoid systems.

  7. Redox-triggered C-C coupling of alcohols and vinyl epoxides: diastereo- and enantioselective formation of all-carbon quaternary centers via tert-(hydroxy)-prenylation.

    Science.gov (United States)

    Feng, Jiajie; Garza, Victoria J; Krische, Michael J

    2014-06-25

    Iridium catalyzed primary alcohol oxidation triggers reductive C-O bond cleavage of isoprene oxide to form aldehyde-allyliridium pairs that combine to form products of tert-(hydroxy)-prenylation, a motif found in >2000 terpenoid natural products. Curtin-Hammett effects are exploited to enforce high levels of anti-diastereo- and enantioselectivity in the formation of an all-carbon quaternary center. The present redox-triggered carbonyl additions occur in the absence of stoichiometric byproducts, premetalated reagents, and discrete alcohol-to-aldehyde redox manipulations. PMID:24915473

  8. Palladium-Catalyzed Asymmetric Conjugate Addition of Arylboronic Acids to Five-, Six-, and Seven-Membered β-Substituted Cyclic Enones: Enantioselective Construction of All-Carbon Quaternary Stereocenters

    KAUST Repository

    Kikushima, Kotaro

    2011-05-11

    The first enantioselective Pd-catalyzed construction of all-carbon quaternary stereocenters via 1,4-addition of arylboronic acids to β-substituted cyclic enones is reported. Reaction of a wide range of arylboronic acids and cyclic enones using a catalyst prepared from Pd(OCOCF(3))(2) and a chiral pyridinooxazoline ligand yields enantioenriched products bearing benzylic stereocenters. Notably, this transformation is tolerant to air and moisture, providing a practical and operationally simple method of synthesizing enantioenriched all-carbon quaternary stereocenters.

  9. Stereogenicity revisited. Proposal of holantimers for comprehending the relationship between stereogenicity and chirality.

    Science.gov (United States)

    Fujita, Shinsaku

    2004-04-30

    The close relationship between stereogenicity and chirality has frequently caused serious confusion in the stereochemistry of organic molecules and inorganic complexes. To clarify the entangled relationship between them, we have proposed the concept of "holantimer". In addition, we have newly defined the concept of "stereoisogram" in order to correlate a set of stereoiomers based on holantimeric and enantiomeric relationships. These concepts have been applied to tetrahedral organic molecules as well as to square-planar inorganic complexes. The stereogenicity characterized by a stereoisogram has been called "RS-stereogenicity", which has been clarified to be a property that should be correlated to chirality. The stereoisograms of tetrahedral molecules have been examined and classified into five types, i.e., type I (chiral/RS-stereogenic), type II (chiral/RS-astereogenic), type III (chiral/RS-stereogenic), type IV (achiral/RS-astereogenic), and type V (achiral/RS-stereogenic), where RS descriptors are concluded to be specified in cases of types I, III, and V. On the other hand, the stereoisograms of square-planar complexes have been classified to two types, i.e., type II and type IV. As a result, the confusion on the RS-nomenclature has been concluded to appear within the RS-stereogenic relationships. Such a new viewpoint of stereogenicity and chirality as described in the present paper provides us with a methodology for restructuring stereochemistry. PMID:15104457

  10. Large-scale green chemical synthesis of adjacent quaternary chiral centers by continuous flow photodecarbonylation of aqueous suspensions of nanocrystalline ketones.

    Science.gov (United States)

    Hernández-Linares, María Guadalupe; Guerrero-Luna, Gabriel; Pérez-Estrada, Salvador; Ellison, Martha; Ortin, Maria-Mar; Garcia-Garibay, Miguel A

    2015-02-01

    To demonstrate the ease of scale-up and synthetic potential of some organic solid state reactions, we report the synthesis, crystallization, and solid state photochemistry of acyclic, homochiral, hexasubstituted (+)-(2R,4S)-2-carbomethoxy-4-cyano-2,4-diphenyl-3-pentanone 1. We demonstrate that solid state photodecarbonylation of (+)-(2R,4S)-1 affords (+)-(2R,3R)-2-carbomethoxy-3-cyano-2,3-diphenyl-butane 2 with two adjacent stereogenic, all-carbon substituted quaternary centers, in quantitative chemical yield and 100% diastereoselectivity and enantiomeric excess. The efficient multigram photodecarbonylation of (+)-(2R,4S)-1 as a nanocrystalline suspension in water using a continuous flow photoreactor shows that the large-scale synthesis of synthetically challenging compounds using photochemical synthesis in the solid state can be executed in a remarkably simple manner. PMID:25578232

  11. Conformational rigidity of silicon-stereogenic silanes in asymmetric catalysis: A comparative study

    Directory of Open Access Journals (Sweden)

    Oestreich Martin

    2007-02-01

    Full Text Available Abstract In recent years, cyclic silicon-stereogenic silanes were successfully employed as stereoinducers in transition metal-catalyzed asymmetric transformations as exemplified by (1 the hydrosilylation of alkenes constituting a chirality transfer from silicon to carbon and (2 the kinetic resolution of racemic mixtures of alcohols by dehydrogenative silicon-oxygen coupling. In this investigation, a cyclic and a structurally related acyclic silane with silicon-centered chirality were compared using the above-mentioned model reactions. The stereochemical outcome of these pairs of reactions was correlated with and rationalized by the current mechanistic pictures. An acyclic silicon-stereogenic silane is also capable of inducing excellent chirality transfer (ct in a palladium-catalyzed intermolecular carbon-silicon bond formation yet silicon incorporated into a cyclic framework is required in the copper-catalyzed silicon-oxygen bond forming reaction.

  12. Efficient and highly enantioselective formation of the all-carbon quaternary stereocentre of lyngbyatoxin A

    DEFF Research Database (Denmark)

    Vital, Paulo J.V.; Tanner, David

    2006-01-01

    Indole 25, an advanced intermediate in a projected enantioselective total synthesis of lyngbyatoxin A 1, was prepared from allylic alcohol 11 in 9 steps and >95% ee, key transformations being the enantiospecific rearrangement of vinyl epoxide 14 and the Hemetsberger-Knittel reaction of azide 24....

  13. Attempts to prepare an all-carbon indigoid system

    OpenAIRE

    Şeref Yildizhan; Henning Hopf; Jones, Peter G

    2015-01-01

    First attempts are described to prepare a precursor for an all-carbon analog of indigo, the tetracyclic triene 4. Starting from indan-2-one (9) the α-methylene ketone 13 was prepared. Upon subjecting this compound to a McMurry coupling reaction, it dimerized to the bis-indene derivative 17, rather than providing the tetramethyl derivative of 4, the hydrocarbon 14. In a second approach, indan-1-one (18) was dimerized to the conjugated enedione 21 through the bis-1-indene dimer 19. All attempts...

  14. Attempts to prepare an all-carbon indigoid system

    Directory of Open Access Journals (Sweden)

    Şeref Yildizhan

    2015-03-01

    Full Text Available First attempts are described to prepare a precursor for an all-carbon analog of indigo, the tetracyclic triene 4. Starting from indan-2-one (9 the α-methylene ketone 13 was prepared. Upon subjecting this compound to a McMurry coupling reaction, it dimerized to the bis-indene derivative 17, rather than providing the tetramethyl derivative of 4, the hydrocarbon 14. In a second approach, indan-1-one (18 was dimerized to the conjugated enedione 21 through the bis-1-indene dimer 19. All attempts to methylenate 21 failed, however. When 19 was treated with the Tebbe reagent, the dimer 23 was produced, presumably through a Cope reaction of the intermediately generated isomer 22. The bis-indene derivative 23 can be alkylated with 1,2-dibromoethane to produce a 1:1 mixture of the spiro compounds 24 and 25. Although 9 could be reductively dimerized to 30, the conversion of this olefin to 14 failed.

  15. Flexible all-carbon photovoltaics with improved thermal stability

    International Nuclear Information System (INIS)

    The structurally robust nature of nanocarbon allotropes, e.g., semiconducting single-walled carbon nanotubes (SWCNTs) and C60s, makes them tantalizing candidates for thermally stable and mechanically flexible photovoltaic applications. However, C60s rapidly dissociate away from the basal of SWCNTs under thermal stimuli as a result of weak intermolecular forces that “lock up” the binary assemblies. Here, we explore use of graphene nanoribbons (GNRs) as geometrically tailored protecting layers to suppress the unwanted dissociation of C60s. The underlying mechanisms are explained using a combination of molecular dynamics simulations and transition state theory, revealing the temperature dependent disassociation of C60s from the SWCNT basal plane. Our strategy provides fundamental guidelines for integrating all-carbon based nano-p/n junctions with optimized structural and thermal stability. External quantum efficiency and output current–voltage characteristics are used to experimentally quantify the effectiveness of GNR membranes under high temperature annealing. Further, the resulting C60:SWCNT:GNR ternary composites display excellent mechanical stability, even after iterative bending tests. - Graphical abstract: The incorporation of solvent resistant, mechanically flexible and electrically addressable 2-D soft graphene nanoribbons facilitates the assembly of photoconductive carbon nano-p/n junctions for thermally stable and flexible photovoltaic cells.

  16. Flexible all-carbon photovoltaics with improved thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chun; Ishihara, Hidetaka; Sodhi, Jaskiranjeet; Chen, Yen-Chang; Siordia, Andrew; Martini, Ashlie; Tung, Vincent C., E-mail: ctung@ucmerced.edu

    2015-04-15

    The structurally robust nature of nanocarbon allotropes, e.g., semiconducting single-walled carbon nanotubes (SWCNTs) and C{sub 60}s, makes them tantalizing candidates for thermally stable and mechanically flexible photovoltaic applications. However, C{sub 60}s rapidly dissociate away from the basal of SWCNTs under thermal stimuli as a result of weak intermolecular forces that “lock up” the binary assemblies. Here, we explore use of graphene nanoribbons (GNRs) as geometrically tailored protecting layers to suppress the unwanted dissociation of C{sub 60}s. The underlying mechanisms are explained using a combination of molecular dynamics simulations and transition state theory, revealing the temperature dependent disassociation of C{sub 60}s from the SWCNT basal plane. Our strategy provides fundamental guidelines for integrating all-carbon based nano-p/n junctions with optimized structural and thermal stability. External quantum efficiency and output current–voltage characteristics are used to experimentally quantify the effectiveness of GNR membranes under high temperature annealing. Further, the resulting C{sub 60}:SWCNT:GNR ternary composites display excellent mechanical stability, even after iterative bending tests. - Graphical abstract: The incorporation of solvent resistant, mechanically flexible and electrically addressable 2-D soft graphene nanoribbons facilitates the assembly of photoconductive carbon nano-p/n junctions for thermally stable and flexible photovoltaic cells.

  17. Creation of a quaternary centre by copper mediated SN2’ substitution with PhMgBr

    DEFF Research Database (Denmark)

    Tønder, Janne Ejrnæs; Ahrenst, Alex B.; Tanner, David Ackland

    In our studies of the formation of quaternary stereogenic centres, we have worked on the addition of arylcoppermagnesium reagents to geranyl chloride. Based on the work published by Bäckvall(1), the primary focus was optimisation of SN2’-substitution versus SN2-substitution. By examination of...... different copper salts, it was found that SN2’-selectivity increased in the following order; CuCl Br...

  18. Resolution of P-stereogenic P-heterocycles via the formation of diastereomeric molecular and coordination complexes (a review).

    Science.gov (United States)

    Bagi, Péter; Ujj, Viktória; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

    2016-02-01

    TADDOL derivatives and the Ca(2+)-salts of tartaric acid derivatives were found to be versatile and generally applicable resolving agents for the preparation of the enantiomers of P-stereogenic heterocyclic phosphine oxides and phosphinates via the formation of the corresponding diastereomeric molecular and coordination complexes. A few of the diastereomeric intermediates were characterized by single crystal X-ray crystallography to gain insights into the binding mode of the corresponding heterocyclic phosphine oxide ("guest") and the resolving agent ("host") and to study the underlying phenomenon of enantiomeric recognition. PMID:26564410

  19. Remote control of helical chirality: thermodynamic resolution of a racemic mixture of CTV units by remote stereogenic centers.

    Science.gov (United States)

    Chatelet, Bastien; Joucla, Lionel; Padula, Daniele; Di Bari, Lorenzo; Pilet, Guillaume; Robert, Vincent; Dufaud, Véronique; Dutasta, Jean-Pierre; Martinez, Alexandre

    2015-02-01

    Enantiopure hemicryptophanes designed from the cyclotriveratrylene (CTV) unit display remarkable properties in selective host-guest recognition or as supramolecular catalysts. The unprecedented control of the helical chirality of the CTV unit by remote stereogenic centers of a tren moiety is reported, providing an original access to this highly promising class of host molecules. Although the chiral centers and the CTV unit are separated by more than 10 Å, one single diastereomer is formed; the nature of the diastereoselective process is discussed and the procedure is exemplified using different enantiopure tren derivatives. This work also highlights the influence of the chirality of the CTV unit on the whole cage structure. PMID:25629235

  20. Synthesis of P-stereogenic diarylphosphinic amides by directed lithiation: transformation into tertiary phosphine oxides via methanolysis, aryne chemistry and complexation behaviour toward zinc(ii).

    Science.gov (United States)

    del Águila-Sánchez, Miguel A; Navarro, Yolanda; García López, Jesús; Guedes, Guilherme P; López Ortiz, Fernando

    2016-02-01

    The highly diastereoselective synthesis of P-stereogenic phosphinic amides via directed ortho lithiation (DoLi) of (SC)-P,P-diphenylphosphinic amides with t-BuLi followed by electrophilic quench reactions is described. Functionalised derivatives containing a wide variety of ortho substituents (Cl, Br, I, OH, N3, SiMe3, SnMe3, P(O)Ph2, Me, allyl, (t)BuOCO) have been prepared in high yields with diastereomeric ratios up to 98 : 2. The X-ray diffraction structure of the ortho-stannylated and ortho-iodo compounds showed that the pro-S P-phenyl ring was stereoselectively ortho-deprotonated by the organolithium base. The usefulness of the method is supported by two key transformations, the synthesis of P-stereogenic methyl phosphinates through replacement of the chiral auxiliary by a methoxy group and the first example of the insertion of benzyne into the P-N bond of a P-stereogenic phosphinic amide. A DFT study of this reaction showed that the insertion proceeds through a [2 + 2] cycloaddition and a subsequent ring-opening with retention of the P-configuration. Explorative coordination chemistry of the new P-stereogenic ligands provided access to a chiral phosphinic amide-phosphine oxide Zn(ii) complex, the crystal structure of which is reported. PMID:26370566

  1. All-Carbon Electrode Consisting of Carbon Nanotubes on Graphite Foil for Flexible Electrochemical Applications

    Directory of Open Access Journals (Sweden)

    Je-Hwang Ryu

    2014-03-01

    Full Text Available We demonstrate the fabrication of an all-carbon electrode by plasma-enhanced chemical vapor deposition for use in flexible electrochemical applications. The electrode is composed of vertically aligned carbon nanotubes that are grown directly on a flexible graphite foil. Being all-carbon, the simple fabrication process and the excellent electrochemical characteristics present an approach through which high-performance, highly-stable and cost-effective electrochemical applications can be achieved.

  2. Second Quaternary dating workshop

    International Nuclear Information System (INIS)

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  3. Second Quaternary dating workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  4. All-carbon-based field effect transistors fabricated by aerosol jet printing on flexible substrates

    International Nuclear Information System (INIS)

    An all-carbon-based field effect transistor (FET) was fabricated on flexible polyethylene terephthalate substrates by the aerosol jet printing method described in this paper. Three different types of homogeneous conductive inks were made and then printed layer-by-layer to form the FET chips. The conducting-reduced graphene oxide was used as electrodes (source and drain) and channel, respectively. Graphene oxide was used as dielectrics while multi-walled carbon nanotubes acted as the gate electrode. The all-carbon-based FET shows a good mobility of 350 cm2 (V s)–1 at a drain bias of −1 V. This simple and novel method explores a promising way to fabricate all-carbon-based, flexible and low-cost electronic devices. (paper)

  5. QUATERNARY GEOLOGY & GEOMORPHOLOGY

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20141664 Abudoukerimu Abasi(Kashi Meteorological Bureau of Xinjiang,Kashi 844000,China);Wang Rongmei The Relationship with Woody Plants Phonological Variation Characters and Climatic Change from 1982to 2010in Kashi(Quaternary Sciences,ISSN1001-7410,CN11-2708/P,33(5),2013,p.927-935,8illus.,3 tables,48 refs.,with English abstract)

  6. Quaternary stratigraphy: Recent changes

    Directory of Open Access Journals (Sweden)

    Gaudenji Tivadar

    2012-01-01

    Full Text Available Corrections to the Quaternary stratigraphic division of Serbia was updated/renewed by lowering limit of the Pleistocene / Quaternary to the beginning of the Gelasian that is at approximately 2.588 million years. Rather than the officially rejected Penck & Brückner Alpine stratigraphic model, the use of oxygen isotope stages (OIS / MIS is recommended. Climatostratigraphic terms glacial and interglacial have a regional applicability and their use is recommended only in areas where there are traces of glaciation, while the terms cold and warm stage (or moderate stages should be used within the global context. Eopleistocene is a regional term for the former Soviet Union and due to its uniqueness it can hardly be applied in the stratigraphical scheme of the Quaternary depostis in Serbia. With the latest extension of the Lower Pleistocene, further use of Eopleistocene would lead to further confusion in stratigraphic correlation as such the use of the Lower / Early Pleistocene or other appropriate stratigraphic units is recommended. [Projekat Ministarstva nauke Republike Srbije, br. 47007

  7. Synthesis and properties of poly(1-phenyL~(-1)-octyne)s containing stereogenic and chromophoric pendant groups

    Institute of Scientific and Technical Information of China (English)

    LAM Jacky W. Y.; QIN AnJun; JIM Cathy K. W.; LU Ping; YUAN WangZhang; DONG YongQiang; DONG YuPing; KWOK Hoi Sing; TANG Ben Zhong

    2009-01-01

    Poly(1-phenyL~(-1)-octyne)s containing different stereogenic and chromophoric pendants {-[(C_6H_(13))C=C(C_6H_4-p-CO_2-R)]_n- R=[(1S)-endo]-(-)-borneyl (P3), (1R,2S,5R)-(-)-menthyl(P4), -C_6H_4-p-(1R,2S,5R)-(-)-menthyl (P5), 2-napthyl (P6), 4-biphenylyl (P7)} have been designed and synthesized. The polymers are prepared in moderate yields by WCl6-Ph4Sn and possess high molecular weights (M_w up to 64000). The structures and properties of the polymers are characterized and evaluated by NMR, TGA, UV, CD, PL, and EL analyses. All the polymers are thermally stable and their temperatures for 5% weight loss locate in the range of 300 to 416℃ under nitrogen. The energy band gaps of all the polymers are ~3.0 eV. Polymers P4 and P5 show CD absorptions associated with the helicity of the polymer segments. Excitation of the THF solutions of P3-P7 by UV irradiation gives strong blue lights of ~485 nm with quantum yields higher than 20%. The thin films of the polymers also emit in the same spectral region, indicative of little aggregation-caused quenching of light emission. Multilayer EL devices with a configuration of ITO/Polymer:PVK/BCP/Alq_3/LiF/Al are constructed, which emit blue lights of ~487 nm. The maximum luminance and external quantum efficiency vary with the pendant groups, with P6 exhibiting the highest external quantum efficiency of 0.16%. The spectra stability of the EL devices is outstanding and the EL peak maximum experiences little change with the applied voltage.

  8. Synthesis and properties of poly(1-phenyl-1-octyne)s containing stereogenic and chromophoric pendant groups

    Institute of Scientific and Technical Information of China (English)

    LAM; Jacky; W.Y.; JIM; Cathy; K.W.; KWOK; Hoi; Sing

    2009-01-01

    Poly(1-phenyl-1-octyne)s containing different stereogenic and chromophoric pendants {-[(C6H13)C=C(C6H4-p-CO2-R)]n-R=[(1S)-endo]-(-)-borneyl (P3), (1R,2S,5R)-(-)-menthyl (P4),―C6H4-p-(1R,2S,5R)-(-)-menthyl (P5), 2-napthyl (P6), 4-biphenylyl (P7)} have been designed and synthesized. The polymers are prepared in moderate yields by WCl6-Ph4Sn and possess high molecular weights (Mw up to 64000). The structures and properties of the polymers are characterized and evaluated by NMR, TGA, UV, CD, PL, and EL analyses. All the polymers are thermally stable and their temperatures for 5% weight loss locate in the range of 300 to 416℃ under nitrogen. The energy band gaps of all the polymers are ~3.0 eV. Polymers P4 and P5 show CD absorptions associated with the helicity of the polymer segments. Excitation of the THF solutions of P3―P7 by UV irradiation gives strong blue lights of ~485 nm with quantum yields higher than 20%. The thin films of the polymers also emit in the same spectral region, indicative of little aggregation-caused quenching of light emission. Multilayer EL devices with a configuration of ITO/Polymer:PVK/BCP/Alq3/LiF/Al are constructed, which emit blue lights of ~487 nm. The maximum luminance and external quantum efficiency vary with the pendant groups, with P6 exhibiting the highest external quantum efficiency of 0.16%. The spectra stability of the EL devices is outstanding and the EL peak maximum experiences little change with the applied voltage.

  9. Asymmetric catalytic formation of quaternary carbons by iminium ion trapping of radicals

    Science.gov (United States)

    Murphy, John J.; Bastida, David; Paria, Suva; Fagnoni, Maurizio; Melchiorre, Paolo

    2016-04-01

    An important goal of modern organic chemistry is to develop new catalytic strategies for enantioselective carbon–carbon bond formation that can be used to generate quaternary stereogenic centres. Whereas considerable advances have been achieved by exploiting polar reactivity, radical transformations have been far less successful. This is despite the fact that open-shell intermediates are intrinsically primed for connecting structurally congested carbons, as their reactivity is only marginally affected by steric factors. Here we show how the combination of photoredox and asymmetric organic catalysis enables enantioselective radical conjugate additions to β,β-disubstituted cyclic enones to obtain quaternary carbon stereocentres with high fidelity. Critical to our success was the design of a chiral organic catalyst, containing a redox-active carbazole moiety, that drives the formation of iminium ions and the stereoselective trapping of photochemically generated carbon-centred radicals by means of an electron-relay mechanism. We demonstrate the generality of this organocatalytic radical-trapping strategy with two sets of open-shell intermediates, formed through unrelated light-triggered pathways from readily available substrates and photoredox catalysts—this method represents the application of iminium ion activation (a successful catalytic strategy for enantioselective polar chemistry) within the realm of radical reactivity.

  10. Asymmetric catalytic formation of quaternary carbons by iminium ion trapping of radicals.

    Science.gov (United States)

    Murphy, John J; Bastida, David; Paria, Suva; Fagnoni, Maurizio; Melchiorre, Paolo

    2016-04-14

    An important goal of modern organic chemistry is to develop new catalytic strategies for enantioselective carbon-carbon bond formation that can be used to generate quaternary stereogenic centres. Whereas considerable advances have been achieved by exploiting polar reactivity, radical transformations have been far less successful. This is despite the fact that open-shell intermediates are intrinsically primed for connecting structurally congested carbons, as their reactivity is only marginally affected by steric factors. Here we show how the combination of photoredox and asymmetric organic catalysis enables enantioselective radical conjugate additions to β,β-disubstituted cyclic enones to obtain quaternary carbon stereocentres with high fidelity. Critical to our success was the design of a chiral organic catalyst, containing a redox-active carbazole moiety, that drives the formation of iminium ions and the stereoselective trapping of photochemically generated carbon-centred radicals by means of an electron-relay mechanism. We demonstrate the generality of this organocatalytic radical-trapping strategy with two sets of open-shell intermediates, formed through unrelated light-triggered pathways from readily available substrates and photoredox catalysts--this method represents the application of iminium ion activation (a successful catalytic strategy for enantioselective polar chemistry) within the realm of radical reactivity. PMID:27075098

  11. Designing electronic anisotropy of three-dimensional carbon allotropes for the all-carbon device

    International Nuclear Information System (INIS)

    Extending two-dimensional (2D) graphene nanosheets to a three-dimensional (3D) network can enhance the design of all-carbon electronic devices. Based on the great diversity of carbon atomic bonding, we have constructed four superlattice-type carbon allotrope candidates, containing sp2-bonding transport channels and sp3-bonding insulating layers, using density functional theory. It was demonstrated through systematic simulations that the ultra-thin insulating layer with only three-atom thickness can switch off the tunneling transport and isolate the electronic connection between the adjacent graphene strips, and these alternating perpendicular strips also extend the electron road from 2D to 3D. Designing electronic anisotropy originates from the mutually perpendicular π bonds and the rare partial charge density of the corresponding carriers in insulating layers. Our results indicate the possibility of producing custom-designed 3D all-carbon devices with building blocks of graphene and diamond

  12. Quaternary chronostratigraphy of south Spitsbergen

    OpenAIRE

    Lindner, Leszek; Marks, Leszek; Pekala, Kazimierz

    1987-01-01

    Recent detailed investigations of Quaternary sediments in south Spitsbergen enabled us to choose several key areas in this region (Lindner et al. 1984, 1986; Butrym et al. 1987). Samples collected in these areas were thermoluminescence and radiocarbon dated, and applied for a chronostratigraphic scheme of the Quaternary for this part of Svalbard (Fig. 1).

  13. Quaternary dating methods

    International Nuclear Information System (INIS)

    The papers in this book cover absolute, relative and multiple dating methods, and have been written by specialists from a number of different earth sciences disciplines - their common interest being the dating of geological materials within the Quaternary. Papers on absolute dating methods discuss radiocarbon, uranium-series, potassium argon, 40Ar/39Ar, paleomagnetic, obsidian hydration, thermoluminescence, amino acid racemization, tree rings, and lichenometric techniques. Those on relative dating include discussions on various geomorphic relative age indicators such as drainage density changes, hypsometric integrals, bifurcation ratios, stream junction angles, spur morphology, hillslope geometry, and till sheet characteristics. The papers on multiple dating cite examples from the Rocky Mountains, Australia, Lake Agassiz Basin, and the Southern Andes. Also included is the panel discussion which reviews and assesses the information presented, and a field trip guide which discusses the sequences of Wisconian tills and interlayered lacustrine and fluvial sediments. (orig.)

  14. All carbon coaxial supercapacitors based on hollow carbon nanotube sleeve structure

    International Nuclear Information System (INIS)

    All carbon coaxial supercapacitors based on hollow carbon nanotube (CNT) sleeve structure are assembled and tested. The key advantage of the structure is that the inner core electrode is variable from CNT sleeve sponges, to CNT fibers, reduced graphene oxide fibers, and graphene woven fabrics. By changing core electrodes from sleeve sponges to CNT fibers, the electrochemical performance has been significantly enhanced. The capacitance based on sleeve sponge + CNT fiber double the capacitances of double-sleeve sponge supercapacitors thanks to reduction of the series and internal resistances. Besides, the coaxial sleeve structure possesses many other features, including high rate capacitance, long cycle life, and good flexibility. (paper)

  15. Two- and Three-Dimensional All-Carbon Nanomaterial Assemblies for Tissue Engineering and Regenerative Medicine.

    Science.gov (United States)

    Lalwani, Gaurav; Patel, Sunny C; Sitharaman, Balaji

    2016-06-01

    Carbon nanomaterials such as carbon nanotubes and graphene have gained significant interest in the fields of materials science, electronics and biomedicine due to their interesting physiochemical properties. Typically these carbon nanomaterials have been dispersed in polymeric matrices at low concentrations to improve the functional properties of nanocomposites employed as two-dimensional (2D) substrates or three-dimensional (3D) porous scaffolds for tissue engineering applications. There has been a growing interest in the assembly of these nanomaterials into 2D and 3D architectures without the use of polymeric matrices, surfactants or binders. In this article, we review recent advances in the development of 2D or 3D all-carbon assemblies using carbon nanotubes or graphene as nanoscale building-block biomaterials for tissue engineering and regenerative medicine applications. PMID:27126776

  16. Eco-friendly all-carbon paper electronics fabricated by a solvent-free drawing method

    Science.gov (United States)

    Kanaparthi, Srinivasulu; Badhulika, Sushmee

    2016-03-01

    Here we report the fabrication of high-performance all-carbon temperature and infrared (IR) sensors with a solvent-free multiwalled carbon nanotube (MWCNT) trace as the sensing element and commercial graphite pencil trace as the electrical contact on recyclable and biodegradable cellulose filter paper without using any toxic materials or complex procedures. The temperature sensor shows a large negative temperature coefficient of resistance (TCR) in the range of -3100 ppm K-1 to -4900 ppm K-1, which is comparable to available commercial temperature sensors, and an activation energy of 34.85 meV. The IR sensor shows a high responsivity of 58.5 V W-1, which is greater than reported IR sensors with similar dimensions. A detailed study of the conduction mechanism in MWCNTs with temperature and the photo response with IR illumination was done and it was found that the conduction is due to thermally assisted hopping in band tails and the photo response is bolometric in nature. The successful fabrication of these sensors on cellulose filter paper with a comparable performance to existing components indicates that it is possible to fabricate high-performance electronics using low-cost, eco-friendly materials without the need for expensive clean-room processing techniques or harmful chemicals.

  17. Quaternary alkaloids of tinospora species.

    Science.gov (United States)

    Bisset, N G; Nwaiwu, J

    1983-08-01

    The occurrence of quaternary alkaloids in TINOSPORA (and PARABAENA) species (Menispermaceae) has been studied. The main components were generally the protoberberine bases berberine and palmatine, with jatrorrhizine an occasional minor constituent, and the aporphine base magnoflorine. Choline was also often present. Only magnoflorine was detected in the PARABAENA material examined. PMID:17404996

  18. Quaternary palaeoecology and ecological theory.

    OpenAIRE

    Rull, Valentí

    1990-01-01

    [EN] A review showing the potential contribution of Quaternary palaeoecology to the ecological theory, focused on the ecosystem evolutionary processes, is presented. By analyzing oceanic and continental Pleistocene and Holocene records, some reflections about ecological succession, diversity, rhythms, predictability, stability, and modelling are made, and compared with theoretical statements derived from neoecology. As a general conclusion, the necessity of considering palaeoecologic...

  19. Quaternary palaeoecology and ecological theory

    OpenAIRE

    Rull del Castillo, Valentí

    1990-01-01

    A review showing the potential contribution of Quaternary palaeoecology to the ecological theory, focused on the ecosystem evolutionary processes, is presented. By analyzing oceanic and continental Pleistocene and Holocene records, some reflections about ecological succession, diversity, rhythms, predictability, stability, and modelling are made, and compared with theoretical statements derived from neoecology. As a general conclusion, the necessity of considering palaeoecological findings in...

  20. Synthesis of Chitosan Quaternary Ammonium Salts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A series of N-alkyl or N-aryl chitosan quaternary ammonium salts were prepared via Schiffs base intermediates. Quaternization of N-substituted chitosan derivatives was carried out using methyl iodide to produce water-soluble cationic chitosan quaternary ammonium salt. The products were characterized by IR, 1HNMR and elemental analysis. The degree of substitution of chitosan quaternary ammonium salt was calculated by elemental analysis.

  1. Synthesis of enantioenriched γ-quaternary cycloheptenones using a combined allylic alkylation/Stork–Danheiser approach: preparation of mono-, bi-, and tricyclic systems

    KAUST Repository

    Bennett, Nathan B.

    2012-01-01

    A general method for the synthesis of β-substituted and unsubstituted cycloheptenones bearing enantioenriched all-carbon γ-quaternary stereocenters is reported. Hydride or organometallic addition to a seven-membered ring vinylogous ester followed by finely tuned quenching parameters achieves elimination to the corresponding cycloheptenone. The resulting enones are elaborated to bi- and tricyclic compounds with potential for the preparation of non-natural analogs and whose structures are embedded in a number of cycloheptanoid natural products.

  2. Recent advances in quaternary geochronology

    International Nuclear Information System (INIS)

    Significant progress has occurred in quaternary geochronology. These include both (i) improvements in Fission Track and Thermoluminescence dating, as well as (ii) new technologies for short-lived (i.e. with half lives 6 yrs) radionuclide measurements as with the 14C or uranium series desequilibrium dating, and finally (iii) the emergence of entirely new dating approches as the Electron Spin Resonnance Method. The aim of this paper is to review these progresses and the new areas they open geochronology for the past-miocene times. (author)

  3. Synthesis and stereochemical assignments of diastereomeric Ni(II complexes of glycine Schiff base with (R-2-(N-{2-[N-alkyl-N-(1-phenylethylamino]acetyl}aminobenzophenone; a case of configurationally stable stereogenic nitrogen

    Directory of Open Access Journals (Sweden)

    Hiroki Moriwaki

    2014-02-01

    Full Text Available A family of chiral ligands derived from α-phenylethylamine and 2-aminobenzophenone were prepared by alkylation of the nitrogen atom. Upon reaction with glycine and a Ni(II salt, these ligands were transformed into diastereomeric complexes, as a result of the configurational stability of the stereogenic nitrogen atom. Different diastereomeric ratios were observed depending on the substituent R introduced in the starting ligand, and stereochemical assignments were based on X-ray analysis, along with NMR studies and optical rotation measurements.

  4. Phosphate Tether-Mediated Ring-Closing Metathesis for the Generation of P-Stereogenic, Z-Configured Bicyclo[7.3.1]- and Bicyclo[8.3.1]phosphates.

    Science.gov (United States)

    Markley, Jana L; Maitra, Soma; Hanson, Paul R

    2016-02-01

    A phosphate tether-mediated ring-closing metathesis (RCM) study to the synthesis of Z-configured, P-stereogenic bicyclo[7.3.1]- and bicyclo[8.3.1]phosphates is reported. Investigations suggest that C3-substitution, olefin substitution, and proximity of the forming olefin to the bridgehead carbon of the bicyclic affect the efficiency and stereochemical outcome of the RCM event. This study demonstrates the utility of phosphate tether-mediated desymmetrization of C2-symmetric, 1,3-anti-diol-containing dienes in the generation of macrocyclic phosphates with potential synthetic and biological utility. PMID:26794367

  5. Cathodoluminescence in Quaternary carbonate deposits

    Science.gov (United States)

    Braithwaite, Colin J. R.

    2016-05-01

    The cathodoluminescent oscillatory and sectoral growth zones common in crystals formed in ancient limestone successions in a variety of putative environments appear to be rare or absent from Recent and Pleistocene marine carbonate sequences. The factors controlling cathodoluminescence and reasons for this disparity are examined. The cathodoluminescent zones in the cements of ancient rocks have been interpreted as responses to variations in the redox potential of formative pore waters during crystal growth; although similar cathodoluminescent behaviour is recorded from some deposits, including travertines and Quaternary speleothems, formed in what are thought to have been strongly oxidizing environments. The apparent absence of cathodoluminescence in the most Recent and Pleistocene marine deposits, that presumably reflect deposition and diagenesis in environments that are also characteristically oxidized, therefore seems anomalous. The controlling influences on cathodoluminescence are reviewed, together with evidence relating to observations of Pleistocene marine deposits and likely conditions of formation but, where it is present, the mechanism(s) for its development remain elusive.

  6. All-carbon vertical van der Waals heterostructures: Non-destructive functionalization of graphene for electronic applications

    OpenAIRE

    Woszczyna, Miroslaw; Winter, Andreas; Grothe, Miriam; Willunat, Annika; Wundrack, Stefan; Stosch, Rainer; Weimann, Thomas; Ahlers, Franz; Turchanin, Andrey

    2014-01-01

    We present a route to non-destructive functionalization of graphene via assembly of vertical all-carbon van der Waals heterostructures. To this end, we employ singlelayer graphene (SLG) sheets grown by low-pressure methane CVD on Cu foils and large-area dielectric ~1 nm thick amino-terminated carbon nanomembranes (NH2-CNMs) generated by electron-beam-induced crosslinking of aromatic self-assembled monolayers. We encapsulate SLG sheets on oxidized silicon wafers with NH2-CNMs via mechanical st...

  7. Late Quaternary changes in climate

    International Nuclear Information System (INIS)

    This review concerns the Quaternary climate with an emphasis on the last 200 000 years. The present state of art in this field is described and evaluated. The review builds on a thorough examination of classic and recent literature. General as well as detailed patterns in climate are described and the forcing factors and feed-back effects are discussed. Changes in climate occur on all time-scales. During more than 90% of the Quaternary period earth has experienced vast ice sheets, i.e. glaciations have been more normal for the period than the warm interglacial conditions we face today. Major changes in climate, such as the 100 000 years glacial/interglacial cycle, are forced by the Milankovitch three astronomical cycles. Because the cycles have different length climate changes on earth do not follow a simple pattern and it is not possible to find perfect analogues of a certain period in the geological record. Recent discoveries include the observation that major changes in climate seem to occur at the same time on both hemispheres, although the astronomical theory implies a time-lag between latitudes. This probably reflects the influence of feed-back effects within the climate system. Another recent finding of importance is the rapid fluctuations that seem to be a normal process. When earth warmed after the last glaciation temperature jumps of up to 10 deg C occurred within less than a decade and precipitation more than doubled within the same time. The forcing factors behind these rapid fluctuations are not well understood but are believed to be a result of major re-organisations in the oceanic circulation. Realizing that nature, on its own, can cause rapid climate changes of this magnitude put some perspective on the anthropogenic global warming debate, where it is believed that the release of greenhouse gases will result in a global warming of a few C. To understand the forcing behind natural rapid climate changes appears as important as to understand the role

  8. Late Quaternary changes in climate

    Energy Technology Data Exchange (ETDEWEB)

    Holmgren, K.; Karlen, W. [Stockholm Univ. (Sweden). Dept. of Physical Geography

    1998-12-01

    This review concerns the Quaternary climate with an emphasis on the last 200 000 years. The present state of art in this field is described and evaluated. The review builds on a thorough examination of classic and recent literature. General as well as detailed patterns in climate are described and the forcing factors and feed-back effects are discussed. Changes in climate occur on all time-scales. During more than 90% of the Quaternary period earth has experienced vast ice sheets, i.e. glaciations have been more normal for the period than the warm interglacial conditions we face today. Major changes in climate, such as the 100 000 years glacial/interglacial cycle, are forced by the Milankovitch three astronomical cycles. Because the cycles have different length climate changes on earth do not follow a simple pattern and it is not possible to find perfect analogues of a certain period in the geological record. Recent discoveries include the observation that major changes in climate seem to occur at the same time on both hemispheres, although the astronomical theory implies a time-lag between latitudes. This probably reflects the influence of feed-back effects within the climate system. Another recent finding of importance is the rapid fluctuations that seem to be a normal process. When earth warmed after the last glaciation temperature jumps of up to 10 deg C occurred within less than a decade and precipitation more than doubled within the same time. The forcing factors behind these rapid fluctuations are not well understood but are believed to be a result of major re-organisations in the oceanic circulation. Realizing that nature, on its own, can cause rapid climate changes of this magnitude put some perspective on the anthropogenic global warming debate, where it is believed that the release of greenhouse gases will result in a global warming of a few C. To understand the forcing behind natural rapid climate changes appears as important as to understand the role

  9. Book Review: Reconstructing Quaternary Environments

    Science.gov (United States)

    Bridgland, David R.; Evans, David J. A.; Roberts, David H.

    2016-02-01

    A third edition of this, the foremost Quaternary textbook, is most welcome, coming seventeen years after the 1997 second edition (which was 13 years after the first). The general impression is one of advancement, not least because of the extensive updating of literature cited and examples used, with the status maintained of an impressive compendium of a specialism with a very wide subject base. Some changes are cosmetic, with chapter and section headers having a more modern style and a profusion of new colour photographs and diagrams. Some of the latter are redrawn from black and white figures in the previous edition, although not all have been improved, as some are smaller and have been simplified. For example, black and white Fig. 3.10 of the Second Edition compares very favourably with the much smaller colour 3.17 in this latest volume (erratic sources). On the plus side, the number change, for a figure that appears in the same place within the chapter, shows that the latest edition is considerably better illustrated than its predecessor, perhaps accounting for a significant proportion of the increased page total (up from 446 to 538).

  10. All-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters

    CERN Document Server

    Picollo, F; Bernardi, E; Plaitano, M; Franchino, C; Gosso, S; Pasquarelli, A; Carbone, E; Olivero, P; Carabelli, V

    2016-01-01

    We report on the ion beam fabrication of all-carbon multi electrode arrays (MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond (SCD) substrates. The fabricated SCD-MEAs are systematically employed for the in vitro simultaneous amperometric detection of the secretory activity from populations of chromaffin cells, demonstrating a new sensing approach with respect to standard techniques. The biochemical stability and biocompatibility of the SCD-based device combined with the parallel recording of multi-electrodes array allow: i) a significant time saving in data collection during drug screening and/or pharmacological tests over a large number of cells, ii) the possibility of comparing altered cell functionality among cell populations, and iii) the repeatition of acquisition runs over many cycles with a fully non-toxic and chemically robust bio-sensitive substrate.

  11. All-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters

    Science.gov (United States)

    Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Plaitano, Marilena; Franchino, Claudio; Gosso, Sara; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2016-02-01

    We report on the ion beam fabrication of all-carbon multi electrode arrays (MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond (SCD) substrates. The fabricated SCD-MEAs are systematically employed for the in vitro simultaneous amperometric detection of the secretory activity from populations of chromaffin cells, demonstrating a new sensing approach with respect to standard techniques. The biochemical stability and biocompatibility of the SCD-based device combined with the parallel recording of multi-electrodes array allow: i) a significant time saving in data collection during drug screening and/or pharmacological tests over a large number of cells, ii) the possibility of comparing altered cell functionality among cell populations, and iii) the repeatition of acquisition runs over many cycles with a fully non-toxic and chemically robust bio-sensitive substrate.

  12. Climate predictors of late quaternary extinctions

    DEFF Research Database (Denmark)

    Nogués-Bravo, David; Ohlemüller, Ralf; Batra, Persaram;

    2010-01-01

    Between 50,000 and 3,000 years before present (BP) 65% of mammal genera weighing over 44 kg went extinct, together with a lower proportion of small mammals. Why species went extinct in such large numbers is hotly debated. One of the arguments proposes that climate changes underlie Late Quaternary...... extinctions, but global quantitative evidence for this hypothesis is still lacking. We test the potential role of global climate change on the extinction of mammals during the Late Quaternary. Our results suggest that continents with the highest climate footprint values, in other words, with climate changes...... of greater magnitudes during the Late Quaternary, witnessed more extinctions than continents with lower climate footprint values, with the exception of South America. Our results are consistent across species with different body masses, reinforcing the view that past climate changes contributed to...

  13. Studies of some lanthanide quaternary complexes

    International Nuclear Information System (INIS)

    Formation constants of mixed ligand quaternary lanthanide complexes of the type M-A-B-L'/L' where M=La3+, Pr3+, Nd3+; A=ethylenediamine N, N, N', N'-tetraacetic acid (EDTA); B=thiodiglycolic acid (TDA); L'=iminodiacetic acid (IDA) and L'=glycine (GLY) have been determined by pH-metric technique at 35±1degC in 0.1 mol dm-3KNO3. Stability constants reveal the orders: La(III)< Pr(III)< Nd(III) in terms of metal ions, binary< ternary< quaternary in terms of complex species, and IDA< Gly in terms of amino acids. The Δ LOG K values are negative for all the ternary and quaternary systems. However, Δ log K values are significantly positive indicating intramolecular hydrophobic ligand-ligand interactions. (author). 16 refs

  14. 40 CFR 721.4095 - Quaternary ammonium alkyltherpropyl trialkylamine halides.

    Science.gov (United States)

    2010-07-01

    ... trialkylamine halides. 721.4095 Section 721.4095 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4095 Quaternary ammonium alkyltherpropyl trialkylamine halides. (a... generically as quaternary ammonium alkyltherpropyl trialkylamine halides (PMNs...

  15. Quaternary sediments in Rybalsryi quarry of Dnipropetrovsk

    Directory of Open Access Journals (Sweden)

    Manyuk V.V.

    2014-12-01

    Full Text Available The results of a study of the typical section of Quaternary sediments in the Rybalske quarry and first time been reported to shift to the South boundary of the spread of the Dneprovian ice cover. Long-term observation of the geological structure subaerial and subaqueous deposits in Quaternary escarpment quarry clearly demonstrates the exceptional value, integrity, and at the same time, a certain exclusivity individual elements Quaternary section. Middle-upper Pleistocene section of substantially exceeds disclosed in Sazhovka draw, where the stratotype Kodatskiy fossil soil and elevated section of Quaternary sediments. If old Kodak can see only fragments section, an opened side by deep ravines and conditions of use cleared, the Rybalske quarry ledge submitted in one complete section alternation fossil soil horizons and loess - loess from the Dnieper to the modern black soil, and another ledge next to, well the rest of the section is exposed (from Tilihulske to Shyrokynske klimatolite. Established that among the many famous sections subaerial deposits located in the Middle Dnieper in the north-eastern part of the Dnieper-Donets basin, in the Black Sea and the Crimea and studied by the author in different years, and described loess and soil horizons (from the Black Sea to the Dnieper differ markedly lack of connectivity, flowability and friability. It is logical to assume that lithofacies conditions of the thicker subaerial deposits in the wellhead part Samara, where the Rybalske quarry markedly different from existing in these areas. Despite the obvious influence of the Dnieper glacier, direct signs which surround Dnipropetrovs’k north must be other reasons not yet explored. It is worth noting another important feature of the section of Quaternary sediments in fishing career. The above section is characteristic of the north-eastern part of the quarry, while the north, at higher marks of the watershed in the lower parts of thicker Quaternary

  16. Quaternary Faults and Stress Regime of Venezuela

    OpenAIRE

    F.A. Audemard M.; A. Singer P.; J-P. Soulas

    2006-01-01

    Spatial configuration of Quaternary active tectonic features along the southern Caribbean plate boundary suggests that the region is subject to a compressive strike-slip (transpressional senso lato) regime, characterized by a NNW-SSE maximum horizontal stress (sH=s1) and/or an ENE-WSW minimum (s h=s3 or s2) horizontal stress. Stress inversion applied to fault-plane kinematic indicators measured essentially in Plio-Quaternary sedimentary rocks confirms this tectonic regime. Accordingly, this s...

  17. Highly Flexible Freestanding Porous Carbon Nanofibers for Electrodes Materials of High-Performance All-Carbon Supercapacitors.

    Science.gov (United States)

    Liu, Ying; Zhou, Jinyuan; Chen, Lulu; Zhang, Peng; Fu, Wenbin; Zhao, Hao; Ma, Yufang; Pan, Xiaojun; Zhang, Zhenxing; Han, Weihua; Xie, Erqing

    2015-10-28

    Highly flexible porous carbon nanofibers (P-CNFs) were fabricated by electrospining technique combining with metal ion-assistant acid corrosion process. The resultant fibers display high conductivity and outstanding mechanical flexibility, whereas little change in their resistance can be observed under repeatedly bending, even to 180°. Further results indicate that the improved flexibility of P-CNFs can be due to the high graphitization degree caused by Co ions. In view of electrode materials for high-performance supercapacitors, this type of porous nanostructure and high graphitization degree could synergistically facilitate the electrolyte ion diffusion and electron transportation. In the three electrodes testing system, the resultant P-CNFs electrodes can exhibit a specific capacitance of 104.5 F g(-1) (0.2 A g(-1)), high rate capability (remain 56.5% at 10 A g(-1)), and capacitance retention of ∼94% after 2000 cycles. Furthermore, the assembled symmetric supercapacitors showed a high flexibility and can deliver an energy density of 3.22 Wh kg(-1) at power density of 600 W kg(-1). This work might open a way to improve the mechanical properties of carbon fibers and suggests that this type of freestanding P-CNFs be used as effective electrode materials for flexible all-carbon supercapacitors. PMID:26449440

  18. Quaternary Prevention and limits in medicine

    Directory of Open Access Journals (Sweden)

    Marc Jamoulle

    2013-12-01

    Full Text Available The concept of Quaternary Prevention, a questioning upon the basis of medical action, was born from the articulation of the doctor-patient relationship. It refers to all medical activities being an important tool for family medicine. It is an ethical question about the excesses of too much and too little medicine which provides some answers.

  19. Montmorillonite modification by quaternary ammonium epoxide

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena; Šabata, Stanislav

    Kochi: India n Society of Nanoscience And Nanotechnology, 2010. s. 1. [Nanotech India 2010. 19.11.2010-21.11.2010, Kochi] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40720504 Keywords : montmorillonite * quaternary ammonium epoxide * intercalation Subject RIV: JI - Composite Materials

  20. Contrasting H-mode behaviour with deuterium fuelling and nitrogen seeding in the all-carbon and metallic versions of JET

    NARCIS (Netherlands)

    Maddison, G. P.; Giroud, C.; Alper, B.; Arnoux, G.; Balboa, I.; Beurskens, M. N. A.; Boboc, A.; Brezinsek, S.; Brix, M.; Clever, M.; Coelho, R.; Coenen, J. W.; Coffey, I.; Belo, da Silva Ares; Devaux, S.; Devynck, P.; Eich, T.; Felton, R. C.; Flanagan, J.; Frassinetti, L.; Garzotti, L.; Groth, M.; Jachmich, S.; Jarvinen, A.; Joffrin, E.; Kempenaars, M.; Kruezi, U.; Lawson, K. D.; Lehnen, M.; Leyland, M. J.; Liu, Y.; Lomas, P. J.; Lowry, C. G.; Marsen, S.; Matthews, G. F.; McCormick, G. K.; Meigs, A. G.; Morris, A. W.; Neu, R.; Nunes, I. M.; Oberkofler, M.; Rimini, F. G.; Saarelma, S.; Sieglin, B.; Sips, A.C.C.; Sirinelli, A.; Stamp, M. F.; van Rooij, G. J.; Ward, D. J.; Wischmeier, M.; JET-EFDA Contributors,

    2014-01-01

    The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between type I H-mode characteristics in each design by examining respective scans over deuterium fuelling an

  1. All-Carbon [3+3] Oxidative Annulations of 1,3-Enynes by Rhodium(III)-Catalyzed C–H Functionalization and 1,4-Migration**

    Science.gov (United States)

    Burns, David J; Best, Daniel; Wieczysty, Martin D; Lam, Hon Wai

    2015-01-01

    1,3-Enynes containing allylic hydrogens cis to the alkyne function as three-carbon components in rhodium(III)-catalyzed, all-carbon [3+3] oxidative annulations to produce spirodialins. The proposed mechanism of these reactions involves the alkenyl-to-allyl 1,4-rhodium(III) migration. PMID:26224377

  2. Clocks for quaternary environments in Australia

    International Nuclear Information System (INIS)

    The Australian continent offers a variety of natural systems where records of the Earth's past environment have been stored, including sediment cores, tree rings, rock surfaces and corals. Rock varnish, mud-wasp nests and pack-rat middens provide alternative archives for vegetation and environmental change in arid areas, where continuous sedimentary sequences or trees are not available. Each of these media contain specific information on past climatic conditions but we must determine their chronology and decipher the relevant environmental parameters. Cosmogenic radionuclides, such as 14C, 10Be, 26Al and 36Cl, analysed by accelerator mass spectrometry, provide valuable radiometric clocks to establish an absolute time scale for the environmental events of the Quaternary. U-series, potassium-argon, argonargon and optically stimulated luminescence are other dating methods used in palaeoenvironmental studies. ANSTO supports the Quaternary science community in Australia providing the analysis of long-lived radionuclides: some significant projects from this program will be illustrated. (author)

  3. Discovery and properties of quaternary borocarbide superconductors

    International Nuclear Information System (INIS)

    The discovery of superconductivity in Y-Ni-B-C by Indian scientists has led to a new class of materials, viz, Quaternary Rare Earth Borocarbides, with many interesting properties. Several members of the series show superconductivity with high Tc for intermetallics with the multiphase Y-Pd-B-C system showing a Tc of 23 K which is highest for bulk intermetallics. Some of the magnetic members of the family exhibit the exotic phenomenon of coexistence of superconductivity with high Tc as well as high magnetic ordering temperatures. The two cooperative phenomena occurring at comparable energy scale results in new aspects of interplay of magnetism and superconductivity. In quaternaries, there is ample scope for finding new materials possibly with even higher Tcs and newer phenomena. A glimpse of this new and exciting field is presented here. (author)

  4. Characterisation of Quaternary sediments from East Anglia

    OpenAIRE

    Mitchell, C J; Bloodworth, A.J.; Evans, E. J.

    1996-01-01

    This report describes the mineralogical investigations of Quaternary sediments,mainly Cromer Till, collected from East Anglia. The main aim of the work was to characterise the mineralogical and physical properties of the till samples to facilitate correlation between tills from different localities. The clast composition of the samples was determined using a binocular microscope and the mineralogy of the matrix was determined using X-ray diffraction and thermogravimetry. Calibration charts we...

  5. PCA for predicting quaternary structure of protein

    Institute of Scientific and Technical Information of China (English)

    Tong WANG; Hongbin SHEN; Lixiu YAO; Jie YANG; Kuochen CHOU

    2008-01-01

    The number and arrangement of subunits that form a protein are referred to as quaternary structure. Knowing the quaternary structure of an uncharacterized protein provides clues to finding its biological function and interaction process with other molecules in a biological system. With the explosion of protein sequences generated in the Post-Genomic Age, it is vital to develop an automated method to deal with such a challenge. To explore this prob-lem, we adopted an approach based on the pseudo position-specific score matrix (Pse-PSSM) descriptor, proposed by Chou and Shen, representing a protein sample. The Pse-PSSM descriptor is advantageous in that it can combine the evolution information and sequence-correlated informa-tion. However, incorporating all these effects into a descriptor may cause 'high dimension disaster'. To over-come such a problem, the fusion approach was adopted by Chou and Shen. A completely different approach, linear dimensionality reduction algorithm principal component analysis (PCA) is introduced to extract key features from the high-dimensional Pse-PSSM space. The obtained dimension-reduced descriptor vector is a compact repre-sentation of the original high dimensional vector. The jack-knife test results indicate that the dimensionality reduction approach is efficient in coping with complicated problems in biological systems, such as predicting the quaternary struc-ture of proteins.

  6. Quaternary evolution of the Caravelas strandplain - Southern Bahia State - Brazil

    OpenAIRE

    Ana C.S. Andrade; José M.L. Dominguez; Louis Martin; ABÍLIO C.S.P. BITTENCOURT

    2003-01-01

    An evolutionary model is proposed for the Caravelas strandplain. The model encompasses integration of: (i) mapping of Quaternary deposits, (ii) cartography of beach-ridge alignments and their truncations, (iii) relative sea-level history, (iv) development history of the Abrolhos coral reefs, (v) vibra-coring and (vi) C14 dating of Quaternary deposits. Seven major evolutionary stages were identified. These stages show that the strandplain has had its Quaternary evolution strongly controlled by...

  7. Synergistically enhanced activity of graphene quantum dots/graphene hydrogel composites: a novel all-carbon hybrid electrocatalyst for metal/air batteries

    Science.gov (United States)

    Wang, Mengran; Fang, Zhao; Zhang, Kai; Fang, Jing; Qin, Furong; Zhang, Zhian; Li, Jie; Liu, Yexiang; Lai, Yanqing

    2016-06-01

    Primary zinc/air batteries could be the next generation of energy storage devices because of their high power density and high safety. Graphene quantum dots nested in the graphene hydrogel have been proposed as excellent all-carbon hybrid oxygen reduction reaction (ORR) catalysts, indicative of their great potential in primary zinc/air batteries.Primary zinc/air batteries could be the next generation of energy storage devices because of their high power density and high safety. Graphene quantum dots nested in the graphene hydrogel have been proposed as excellent all-carbon hybrid oxygen reduction reaction (ORR) catalysts, indicative of their great potential in primary zinc/air batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02622b

  8. Contrasting H-mode behaviour with deuterium fuelling and nitrogen seeding in the all-carbon and metallic versions of JET

    CERN Document Server

    Maddison, G P; Alper, B; Arnoux, G; Balboa, I; Beurskens, M N A; Boboc, A; Brezinsek, S; Brix, M; Clever, M; Coelho, R; Coenen, J W; Coffey, I; Belo, P C da Silva Aresta; Devaux, S; Devynck, P; Eich, T; Felton, R C; Flanagan, J; Frassinetti, L; Garzotti, L; Groth, M; Jachmich, S; Järvinen, A; Joffrin, E; Kempenaars, M A H; Kruezi, U; Lawson, K D; Lehnen, M; Leyland, M J; Liu, Y; Lomas, P J; Lowry, C G; Marsen, S; Matthews, G F; McCormick, G K; Meigs, A G; Morris, A W; Neu, R; Nunes, I M; Oberkofler, M; Rimini, F G; Saarelma, S; Sieglin, B; Sips, A C C; Sirinelli, A; Stamp, M F; van Rooij, G J; Ward, D J; Wischmeier, M; contributors, JET EFDA

    2014-01-01

    The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between Type I H-mode characteristics in each design by examining respective scans over deuterium fuelling and impurity seeding, required to ameliorate exhaust loads both in JET at full capability and in ITER.

  9. Ultrafast electron transfer in all-carbon-based SWCNT-C60 donor-acceptor nanoensembles connected by poly(phenylene-ethynylene) spacers.

    Science.gov (United States)

    Barrejón, Myriam; Gobeze, Habtom B; Gómez-Escalonilla, María J; Fierro, José Luis G; Zhang, Minfang; Yudasaka, Masako; Iijima, Sumio; D'Souza, Francis; Langa, Fernando

    2016-08-21

    Building all-carbon based functional materials for light energy harvesting applications could be a solution to tackle and reduce environmental carbon output. However, development of such all-carbon based donor-acceptor hybrids and demonstration of photoinduced charge separation in such nanohybrids is a challenge since in these hybrids part of the carbon material should act as an electron donating or accepting photosensitizer while the second part should fulfil the role of an electron acceptor or donor. In the present work, we have successfully addressed this issue by synthesizing covalently linked all-carbon-based donor-acceptor nanoensembles using single-walled carbon nanotubes (SWCNTs) as the donor and C60 as the acceptor. The donor-acceptor entities in the nanoensembles were connected by phenylene-ethynylene spacer units to achieve better electronic communication and to vary the distance between the components. These novel SWCNT-C60 nanoensembles have been characterized by a number of techniques, including TGA, FT-IR, Raman, AFM, absorbance and electrochemical methods. The moderate number of fullerene addends present on the side-walls of the nanotubes largely preserved the electronic structure of the nanotubes. The thermodynamic feasibility of charge separation in these nanoensembles was established using spectral and electrochemical data. Finally, occurrence of ultrafast electron transfer from the excited nanotubes in these donor-acceptor nanohybrids has been established by femtosecond transient absorption studies, signifying their utility in building light energy harvesting devices. PMID:27305145

  10. Shifting Sediment Sources in the Quaternary Nile

    Science.gov (United States)

    Woodward, Jamie; Macklin, Mark; Fielding, Laura; Millar, Ian; Williams, Martin

    2016-04-01

    Invited Paper The Nile basin contains the longest river channel system in the world and drains about one tenth of the African continent. A dominant characteristic of the modern Nile is the marked spatial and temporal variability in the flux of water and sediment. Because the major headwater basins of the Nile are linked to key elements of the global climate system, the sedimentary records in the basin have attracted good deal of attention from the Quaternary palaeoclimate and palaeohydrology communities. Various approaches (from heavy minerals to strontium isotopes) have been employed to examine present and past patterns of sediment yield in the basin. A good deal of work has been carried out on the long sediment records in the delta and offshore which provide high resolution archives of hydrological changes in the upstream basin as well fluctuations in the input of dust from the desert. The sediment load of the modern desert Nile (downstream of Khartoum) is dominated by sediment inputs from the Blue Nile (61 +/- 5%) and Atbara (35 +/- 4%), whilst the White Nile contribution is meagre (3 +/- 2%) (Padoan et al. 2011). Recent work has shown that these values were very different during humid phases of the Quaternary when stronger Northern Hemisphere summer insolation produced wetter conditions across North Africa. In the early Holocene, for example, the Nile floodplain in Northern Sudan shows a tributary wadi input of 40-50%. This paper will review three decades of work on the sediment delivery dynamics of the Quaternary Nile and explore their palaeoclimatic implications. Padoan, M., Garzanti, E., Harlavan, Y., Villa, I.M. (2011) Tracing Nile sediment sources by Sr and Nd isotope signatures (Uganda, Ethiopia, Sudan). Geochim. Cosmochim. Acta 75 (12), 3627-3644.

  11. THE BINARY IMAGE OF THE DUAL OF QUATERNARY GOETHALS CODE

    Institute of Scientific and Technical Information of China (English)

    崔杰

    2002-01-01

    The 2-adic representations of codewords of the dual of quaternary Goethals code are given. By the 2-adic representations, the binary image of the dual of quaternary Goethals code under the Gray map is proved to be the nonlinear code constructed by Goethals in 1976.

  12. Determination of quaternary strata diggability with bucket wheel excavators

    Energy Technology Data Exchange (ETDEWEB)

    Ural, S.; Onur, A.H. [Afsin-Elbistan Lignite Establishment (Turkey)

    1994-12-31

    This paper relates the field investigations of the Quaternary strata series diggability with a bucket wheel excavator (BWE), carried out in Afsin-Elbistan Lignite Establishment (AEL). The investigations were intended to determine the Quaternary strata diggability and, in particular, to define the relative difficulty of excavating in-situ and preblasted layers. 3 refs., 11 figs., 3 tabs.

  13. Quaternary Ammonium Polyethyleneimine: Antibacterial Activity Ira

    International Nuclear Information System (INIS)

    Quaternary ammonium polyethyleneimine- (QA-PEI-) based nanoparticles were synthesized using two synthetic methods, reductive amination and N-alkylation. According to the first method, QA-PEI nanoparticles were synthesized by cross-linking with glutaraldehyde followed by reductive amination with octanal and further N-methylation with methyl iodide. The second method is based on crosslinking with dialkyl halide followed by N-alkylation with octyl halide and further N-methylation with methyl iodide. QA-PEI nanoparticles completely inhibited bacterial growth (>106 bacteria), including both Gram-positive, that is, Staphylococcus aureus at 80 μ/mL, and Gram-negative, that is, Escherichia coli at 320 μ/mL. Activity analysis revealed that the degree of alkylation and N-methylation of the QA-PEI nanoparticles plays a significant role in antibacterial activity of the reagent. The most potent compound was octyl alkylated QA-PEI alkylated at 1 : 1 mole ratio (primary amine of PEI monomer units/alkylating agent). Also, cytotoxicity studies on MAT-LyLu and MBT cell lines were performed with QA-PEI nanoparticles. These findings confirm previous reports that poly cations bearing quaternary ammonium moieties inhibit bacterial growth in vitro and have a potential use as additives in medical devices which need antibacterial properties.

  14. Late Quaternary climate change shapes island biodiversity.

    Science.gov (United States)

    Weigelt, Patrick; Steinbauer, Manuel Jonas; Cabral, Juliano Sarmento; Kreft, Holger

    2016-04-01

    Island biogeographical models consider islands either as geologically static with biodiversity resulting from ecologically neutral immigration-extinction dynamics, or as geologically dynamic with biodiversity resulting from immigration-speciation-extinction dynamics influenced by changes in island characteristics over millions of years. Present climate and spatial arrangement of islands, however, are rather exceptional compared to most of the Late Quaternary, which is characterized by recurrent cooler and drier glacial periods. These climatic oscillations over short geological timescales strongly affected sea levels and caused massive changes in island area, isolation and connectivity, orders of magnitude faster than the geological processes of island formation, subsidence and erosion considered in island theory. Consequences of these oscillations for present biodiversity remain unassessed. Here we analyse the effects of present and Last Glacial Maximum (LGM) island area, isolation, elevation and climate on key components of angiosperm diversity on islands worldwide. We find that post-LGM changes in island characteristics, especially in area, have left a strong imprint on present diversity of endemic species. Specifically, the number and proportion of endemic species today is significantly higher on islands that were larger during the LGM. Native species richness, in turn, is mostly determined by present island characteristics. We conclude that an appreciation of Late Quaternary environmental change is essential to understand patterns of island endemism and its underlying evolutionary dynamics. PMID:27027291

  15. Ultrafast electron transfer in all-carbon-based SWCNT-C60 donor-acceptor nanoensembles connected by poly(phenylene-ethynylene) spacers

    Science.gov (United States)

    Barrejón, Myriam; Gobeze, Habtom B.; Gómez-Escalonilla, María J.; Fierro, José Luis G.; Zhang, Minfang; Yudasaka, Masako; Iijima, Sumio; D'Souza, Francis; Langa, Fernando

    2016-08-01

    Building all-carbon based functional materials for light energy harvesting applications could be a solution to tackle and reduce environmental carbon output. However, development of such all-carbon based donor-acceptor hybrids and demonstration of photoinduced charge separation in such nanohybrids is a challenge since in these hybrids part of the carbon material should act as an electron donating or accepting photosensitizer while the second part should fulfil the role of an electron acceptor or donor. In the present work, we have successfully addressed this issue by synthesizing covalently linked all-carbon-based donor-acceptor nanoensembles using single-walled carbon nanotubes (SWCNTs) as the donor and C60 as the acceptor. The donor-acceptor entities in the nanoensembles were connected by phenylene-ethynylene spacer units to achieve better electronic communication and to vary the distance between the components. These novel SWCNT-C60 nanoensembles have been characterized by a number of techniques, including TGA, FT-IR, Raman, AFM, absorbance and electrochemical methods. The moderate number of fullerene addends present on the side-walls of the nanotubes largely preserved the electronic structure of the nanotubes. The thermodynamic feasibility of charge separation in these nanoensembles was established using spectral and electrochemical data. Finally, occurrence of ultrafast electron transfer from the excited nanotubes in these donor-acceptor nanohybrids has been established by femtosecond transient absorption studies, signifying their utility in building light energy harvesting devices.Building all-carbon based functional materials for light energy harvesting applications could be a solution to tackle and reduce environmental carbon output. However, development of such all-carbon based donor-acceptor hybrids and demonstration of photoinduced charge separation in such nanohybrids is a challenge since in these hybrids part of the carbon material should act as an

  16. Quaternary Faults and Stress Regime of Venezuela

    Directory of Open Access Journals (Sweden)

    F.A. Audemard M.

    2006-12-01

    Full Text Available Spatial configuration of Quaternary active tectonic features along the southern Caribbean plate boundary suggests that the region is subject to a compressive strike-slip (transpressional senso lato regime, characterized by a NNW-SSE maximum horizontal stress (sH=s1 and/or an ENE-WSW minimum (s h=s3 or s2 horizontal stress. Stress inversion applied to fault-plane kinematic indicators measured essentially in Plio-Quaternary sedimentary rocks confirms this tectonic regime. Accordingly, this stress regime is responsible for the Quaternary activity and kinematics of six sets of brittle features along northern Venezuela (from Colombia in the west to Trinidad in the east: (1 east-west rightlateral faults, (2 NW right-lateral faults -acting as synthetic Riedel shears-, (3 ENE to east-west dextral faults -P shears-, (4 NNW normal faults, (5 almost north-south left-lateral faults -antithetic Riedel shears- and (6 mostly subsurface ENE reverse faults associated with folding of the same orientation. Brittle deformation conforms to the simple shear model, although not all the deformation can be accounted for it since strain partitioning is also taking place because regional folding and thrusting are due to the normal-to-structure component of the relative slip vector between the Caribbean and South America plates. On the other hand, the maximum horizontal stress in western Venezuela, particularly in the Maracaibo block and south of the Oca-Ancón fault, progressively turns counter-clockwise to become more east-west oriented, producing left- and right-lateral slip along the north-south striking and NE-SW striking faults, respectively. The orientation and spatial variation of this regional stress field in western Venezuela results from the superposition of the two major neighboring interplate maximum horizontal stress orientations (sH: roughly east-west trending stress across the Nazca-South America type-B subduction along the pacific coast of Colombia and NNW

  17. Absolute age determination of quaternary faults

    International Nuclear Information System (INIS)

    To constrain the age of neotectonic fault movement, Rb-Sr, K-Ar, U-series disequilibrium, C-14 and Be-10 methods were applied to the fault gouges, fracture infillings and sediments from the Malbang, Ipsil, Wonwonsa faults faults in the Ulsan fault zone, Yangsan fault in the Yeongdeog area and southeastern coastal area. Rb-Sr and K-Ar data imply that the fault movement of the Ulan fault zone initiated at around 30 Ma and preliminary dating result for the Yang san fault is around 70 Ma in the Yeongdeog area. K-Ar and U-series disequilibrium dating results for fracture infillings in the Ipsil fault are consistent with reported ESR ages. Radiocarbon ages of quaternary sediments from the Jeongjari area are discordant with stratigraphic sequence. Carbon isotope data indicate a difference of sedimentry environment for those samples. Be-10 dating results for the Suryum fault area are consistent with reported OSL results

  18. Quaternary ammonium compounds – New occupational hazards

    Directory of Open Access Journals (Sweden)

    Agnieszka Lipińska-Ojrzanowska

    2014-10-01

    Full Text Available Quaternary ammonium compounds (QACs, quats belong to organic ionic chemical agents which display unique properties of both surfactants and disinfectants. Their wide distribution in the work environment and also in private households brings about new occupational hazards. This paper reviews reports about the health effects of QACs. QACs could play a role of sensitizers and irritants to the skin and mucous membranes. It is suspected that particular QACs can display an immunologic crossreactivity between each other and with other chemical compounds containing ammonium ion, such as muscle relaxants widely used in anesthesia. They may promote the development of airway allergy, however, the background mechanisms are still unclear and need to be further investigated. Until now, a few cases of occupational asthma induced by QACs have been described and their involvement in contact dermatitis has been documented. The possibility of anaphylaxis due to QACs cannot be excluded as well. Med Pr 2014;65(5:675–682

  19. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  20. Late Quaternary climate change shapes island biodiversity

    DEFF Research Database (Denmark)

    Weigelt, Patrick; Steinbauer, Manuel; Cabral, Juliano;

    2016-01-01

    sea levels3, 4 and caused massive changes in island area, isolation and connectivity5, orders of magnitude faster than the geological processes of island formation, subsidence and erosion considered in island theory2, 6. Consequences of these oscillations for present biodiversity remain unassessed5, 7......Island biogeographical models consider islands either as geologically static with biodiversity resulting from ecologically neutral immigration–extinction dynamics1, or as geologically dynamic with biodiversity resulting from immigration–speciation–extinction dynamics influenced by changes in island...... diversity of endemic species. Specifically, the number and proportion of endemic species today is significantly higher on islands that were larger during the LGM. Native species richness, in turn, is mostly determined by present island characteristics. We conclude that an appreciation of Late Quaternary...

  1. Absolute age determination of quaternary faults

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Chang Sik; Lee, Seok Hoon; Choi, Man Sik [Korea Basic Science Institute, Seoul (Korea, Republic of)] (and others)

    2000-03-15

    To constrain the age of neotectonic fault movement, Rb-Sr, K-Ar, U-series disequilibrium, C-14 and Be-10 methods were applied to the fault gouges, fracture infillings and sediments from the Malbang, Ipsil, Wonwonsa faults faults in the Ulsan fault zone, Yangsan fault in the Yeongdeog area and southeastern coastal area. Rb-Sr and K-Ar data imply that the fault movement of the Ulan fault zone initiated at around 30 Ma and preliminary dating result for the Yang san fault is around 70 Ma in the Yeongdeog area. K-Ar and U-series disequilibrium dating results for fracture infillings in the Ipsil fault are consistent with reported ESR ages. Radiocarbon ages of quaternary sediments from the Jeongjari area are discordant with stratigraphic sequence. Carbon isotope data indicate a difference of sedimentry environment for those samples. Be-10 dating results for the Suryum fault area are consistent with reported OSL results.

  2. The Plio Quaternary Ambon arc, Eastern Indonesia

    Science.gov (United States)

    Honthaas, Christian; Maury, René C.; Priadi, Bambang; Bellon, Hervé; Cotten, Joseph

    1999-01-01

    Plio-Quaternary lavas and granites have been collected from Ambon, Seram, Kelang, Haruku, Saparua, Ambelau and Banda Api islands, Eastern Indonesia. They include low-K calc-alkaline basalts, andesites, dacites and rhyolites and high-K calc-alkaline andesites, dacites, rhyolites and granites. All these rocks present the usual chemical characteristics of island-arc magmas. The high-K suite of Ambon is mostly represented by cordierite-bearing dacites (known as ambonites) and granites. Low-K and high-K magmas were emplaced in neighbouring islands or even in the same island (Ambon), often concomitantly, during two magmatic pulses at 5-3.2 Ma and 2.3-1 Ma, respectively. We propose that the low-K suite results from the evolution of basaltic magmas derived from mantle melting above the Western Irian Jaya plate which subducts along the Seram trough. Intermediate and acidic rocks of the high-K suite (e.g. ambonites) are thought to derive from low-K mafic magmas through massive assimilation of the Seram-Ambon continental crust, as originally proposed by Van Bemmelen in 1949. The timing of magmatic events and the geochemical features of the studied lavas are clearly different from those of the southern part of the Banda arc, in which the low-K suite is lacking. In agreement with earlier seismic evidence for two different slabs subducting beneath the Seram-Ambon continental block and beneath the southern Banda arc (from Wetar to Manuk), respectively, we propose to recognise a new Plio-Quaternary island arc, i.e. the Ambon arc, extending west-east from Ambelau to the Banda Archipelago active low-K volcanoes through Kelang, southwestern Seram, Ambon, Haruku and Saparua.

  3. Quaternary Logic and Applications Using Multiple Quantum Well Based SWSFETs

    Directory of Open Access Journals (Sweden)

    P. Gogna

    2012-11-01

    Full Text Available This paper presents Spatial Wavefunction-Switched Field-Effect Transistors (SWSFET to implement efficient quaternary logic and arithmetic functions. Various quaternary logic gates and digital building blocks are presented using SWSFETs. In addition, arithmetic operation with full adder using novel logic algebra is also presented. The SWSFET based implementation of digital logic, cache and arithmetic block results in up to 75% reduction in transistor count and up to 50% reduction in data interconnect densities. Simulations of quaternary logic gates using the BSIM equivalent models for SWSFET channels are also described.

  4. Quaternary Logic and Applications Using Multiple Quantum Well Based SWSFETs

    Directory of Open Access Journals (Sweden)

    P. Gogna

    2012-10-01

    Full Text Available This paper presents Spatial Wavefunction-Switched Field-Effect Transistors (SWSFET to implement efficient quaternary logic and arithmetic functions. Various quaternary logic gates and digital building blocks are presented using SWSFETs. In addition, arithmetic operation with full adder using novel logic algebra is also presented. The SWSFET based implementation of digital logic, cache and arithmetic block results in up to 75% reduction in transistor count and up to 50% reduction in data interconnect densities. Simulations of quaternary logic gates using the BSIM equivalent models for SWSFET channels are also described.

  5. Highly Enantioselective Formation of α-Allyl-α-Arylcyclopentanones via Pd-Catalysed Decarboxylative Asymmetric Allylic Alkylation.

    Science.gov (United States)

    Akula, Ramulu; Doran, Robert; Guiry, Patrick J

    2016-07-11

    A highly enantioselective Pd-catalysed decarboxylative asymmetric allylic alkylation of cyclopentanone derived α-aryl-β-keto esters employing the (R,R)-ANDEN-phenyl Trost ligand has been developed. The product (S)-α-allyl-α-arylcyclopentanones were obtained in excellent yields and enantioselectivities (up to >99.9 % ee). This represents one of the most highly enantioselective formations of an all-carbon quaternary stereogenic center reported to date. This reaction was demonstrated on a 4.0 mmol scale without any deterioration of enantioselectivity and was exploited as the key enantioselective transformation in an asymmetric formal synthesis of the natural product (+)-tanikolide. PMID:27191198

  6. Comparison of GPS and Quaternary slip rates: Insights from a new Quaternary fault database for Central Asia

    Science.gov (United States)

    Mohadjer, Solmaz; Ehlers, Todd; Bendick, Rebecca; Mutz, Sebastian

    2016-04-01

    Previous studies related to the kinematics of deformation within the India-Asia collision zone have relied on slip rate data for major active faults to test kinematic models that explain the deformation of the region. The slip rate data, however, are generally disputed for many of the first-order faults in the region (e.g., Altyn Tagh and Karakorum faults). Several studies have also challenged the common assumption that geodetic slip rates are representative of Quaternary slip rates. What has received little attention is the degree to which geodetic slip rates relate to Quaternary slip rates for active faults in the India-Asia collision zone. In this study, we utilize slip rate data from a new Quaternary fault database for Central Asia to determine the overall relationship between Quaternary and GPS-derived slip rates for 18 faults. The preliminary analysis investigating this relationship uses weighted least squares and a re-sampling analysis to test the sensitivity of this relationship to different data point attributes (e.g., faults associated with data points and dating methods used for estimating Quaternary slip rates). The resulting sample subsets of data points yield a maximum possible Pearson correlation coefficient of ~0.6, suggesting moderate correlation between Quaternary and GPS-derived slip rates for some faults (e.g., Kunlun and Longmen Shan faults). Faults with poorly correlated Quaternary and GPS-derived slip rates were identified and dating methods used for the Quaternary slip rates were examined. Results indicate that a poor correlation between Quaternary and GPS-derived slip rates exist for the Karakorum and Chaman faults. Large differences between Quaternary and GPS slip rates for these faults appear to be connected to qualitative dating of landforms used in the estimation of the Quaternary slip rates and errors in the geomorphic and structural reconstruction of offset landforms (e.g., offset terrace riser reconstructions for Altyn Tagh fault

  7. Quaternary alluvial stratigraphy and palaeoclimatic reconstruction at the Thar margin

    DEFF Research Database (Denmark)

    Jain, M.; Tandon, S.K.

    2003-01-01

    Quaternary alluvial record at the Thar desert margin has been examined using the exposed succession along Mahudi, Sabarmati river, Western India. Different alluvial facies, their associations and granulometry have been studied for palaeoenvironmental reconstruction. Clay mineral indices smectite...

  8. Mollusks of warm water in the marine quaternary Uruguay

    International Nuclear Information System (INIS)

    This review examines the mollusks present in the warm water of the marine quaternary associations in Uruguay, with an analysis which allows to increase the knowledge paleo ecological, environmental and biogeographical

  9. Quaternary alluvial stratigraphy and palaeoclimatic reconstruction at the Thar margin

    DEFF Research Database (Denmark)

    Jain, M.; Tandon, S.K.

    2003-01-01

    Quaternary alluvial record at the Thar desert margin has been examined using the exposed succession along Mahudi, Sabarmati river, Western India. Different alluvial facies, their associations and granulometry have been studied for palaeoenvironmental reconstruction. Clay mineral indices smectite/...

  10. Quaternary seismo-tectonic activity of the Polochic Fault, Guatemala

    OpenAIRE

    Authemayou, Christine; Brocard, Gilles; TEYSSIER, Christian; Suski, Barbara; Cosenza, Beatriz; Moran-Ical, Sergio; Gonzalez-Veliz, Claussen Walther; Aguilar-Hengstenberg, Miguel Angel; Holliger, Klaus

    2012-01-01

    The Polochic-Motagua fault system is part of the sinistral transform boundary between the North American and Caribbean plates in Guatemala and the associated seismic activity poses a threat to ∼70% of the country's population. The aim of this study is to constrain the Late Quaternary activity of the Polochic fault by determining the active structure geometry and quantifying recent displacement rates as well as paleo-seismic events. Slip rates have been estimated from offsets of Quaternary vol...

  11. An Overview of the Main Quaternary Deformation of South America

    Directory of Open Access Journals (Sweden)

    C.H. Costa

    2006-12-01

    Full Text Available Deformation affecting continental South America during Quaternary is related to the Neogene geodynamic processes. These structures are mainly controlled by anisotropies inherited after a long and complex history as well as by the kinematic and geometric features of the ongoing plate interaction. Main Quaternary structures at both ends of South America are directly linked to plate interaction and some of them are considered to be plate boundaries. The main structures with Quaternary activity along the Caribbean coast have an E-W trend and a strike-slip regime. Between the Venezuelan Andes and the Gulf of Guayaquil, NE trending structures are dominant, with a kinematic regime ranging from strike-slip to transpressive and compressive. At the Central Andes (4ºS-46º30'S most Quaternary deformation results from a complex stress distribution and stress-partitioning at the interior of the South American plate, reactivating preexisting discontinuities. The present geometry of the subducted Nazca plate is here the main control with respect to the distribution and characteristics of Quaternary deformation, being them better exposed at the Andean eastern slope and foreland regions. The main structure with Quaternary activity at the southernmost Andes is represented at Tierra del Fuego by a left-lateral transform boundary, resulting from the South American and Scotia plate interaction.

  12. Mutagenicity of quaternary ammonium salts containing carbohydrate moieties

    International Nuclear Information System (INIS)

    Highlights: → A series of quaternary ammonium salts containing carbohydrate moieties, with configuration D-galacto, D-gluco and D-manno, was synthesized and characterized. → The quaternary ammonium salts containing carbohydrate moieties revealed potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. → The N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. → We suggest that quaternary ammonium salts may be more hazardous than previously supposed. - Abstract: Quaternary ammonium salts are widely used in industrial, agricultural, healthcare and domestic applications. They are believed to be safe compounds, with little or no health hazard to humans. However, in this report, we demonstrate that a series of newly synthesized quaternary ammonium salts containing carbohydrate moieties reveal potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. D-Gluco- and D-galacto-derivatives were found to have a higher mutagenic potential than D-manno-derivatives. Among the former groups of compounds, the N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. These results suggest that the safety of quaternary ammonium salts may be lower than previously supposed, indicating a need for testing such compounds for their mutagenicity.

  13. Mutagenicity of quaternary ammonium salts containing carbohydrate moieties

    Energy Technology Data Exchange (ETDEWEB)

    Dmochowska, Barbara [Department of Carbohydrate Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Piosik, Jacek; Woziwodzka, Anna [Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Kladki 24, 80-822 Gdansk (Poland); Sikora, Karol; Wisniewski, Andrzej [Department of Carbohydrate Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Wegrzyn, Grzegorz, E-mail: wegrzyn@biotech.univ.gda.pl [Department of Molecular Biology, University of Gdansk, Kladki 24, 80-822 Gdansk (Poland)

    2011-10-15

    Highlights: {yields} A series of quaternary ammonium salts containing carbohydrate moieties, with configuration D-galacto, D-gluco and D-manno, was synthesized and characterized. {yields} The quaternary ammonium salts containing carbohydrate moieties revealed potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. {yields} The N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. {yields} We suggest that quaternary ammonium salts may be more hazardous than previously supposed. - Abstract: Quaternary ammonium salts are widely used in industrial, agricultural, healthcare and domestic applications. They are believed to be safe compounds, with little or no health hazard to humans. However, in this report, we demonstrate that a series of newly synthesized quaternary ammonium salts containing carbohydrate moieties reveal potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. D-Gluco- and D-galacto-derivatives were found to have a higher mutagenic potential than D-manno-derivatives. Among the former groups of compounds, the N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. These results suggest that the safety of quaternary ammonium salts may be lower than previously supposed, indicating a need for testing such compounds for their mutagenicity.

  14. Quaternary Tectonics of The Vitosha Mountain (bulgaria)

    Science.gov (United States)

    Angelova, Dora

    The Vitosha Mt. is a Cretaceous paleovolcano of the central type with complex ge- ological evolution. From a contemporary point of view it has a marked orographic homogeneity, which is connected with its specific evolution during the Neogene and the Quaternary. At the background of intensive vault formation, graben systems from the Maritsa and Strouma fault zones originated in a sharp discordance along its pe- riphery. The vault formation process caused the accumulation of tectonic stresses in different parts of the Vitosha Mt. in the course of time and space. The tectonic stresses provoked the formation of concentric normal faults. Their surface display predeter- mined not only the block disintegration of the structure but also its primary relief. The active mountain formation of Vitosha was controlled by the Pernik and Vladaya fault zones, and by the Vitosha, Zheleznitsa, Matnitsa and Chuipetlovo fault beams during the Quaternary. The Pliocene-Pleistocene boundary was accompanied by active ver- tical tectonic deformations. As a result of pulse tectonic movements and subsequent deformations along the above mentioned structures, a global re-arrangement of the Vladaiska and Strouma River basins took place in the region of the Vladaya village and to the south of the Chuipetlovo village. The age of these events is 0.73 Ma. The pa- leoseismic dislocation in the region of the Dragalevtsi quarter was probably formed at the same time. The paleoseismic deformations during the Middle Pleistocene were es- tablished along the radial faults. They had caused rock-falls in the Douhlata cave, pyra- teries and bifurcations of the underground aquatic system and of the Klisuritsa River. The Holocene stage was characterised by intensified vertical movements along all fault structures together with the climatic changes under post-glacial circumstances. The Vitosha paleovolcano was mightily raised due to the vertical compression and new river system originated while the old one was

  15. A Quaternary fault database for central Asia

    Science.gov (United States)

    Mohadjer, Solmaz; Ehlers, Todd Alan; Bendick, Rebecca; Stübner, Konstanze; Strube, Timo

    2016-02-01

    Earthquakes represent the highest risk in terms of potential loss of lives and economic damage for central Asian countries. Knowledge of fault location and behavior is essential in calculating and mapping seismic hazard. Previous efforts in compiling fault information for central Asia have generated a large amount of data that are published in limited-access journals with no digital maps publicly available, or are limited in their description of important fault parameters such as slip rates. This study builds on previous work by improving access to fault information through a web-based interactive map and an online database with search capabilities that allow users to organize data by different fields. The data presented in this compilation include fault location, its geographic, seismic, and structural characteristics, short descriptions, narrative comments, and references to peer-reviewed publications. The interactive map displays 1196 fault traces and 34 000 earthquake locations on a shaded-relief map. The online database contains attributes for 123 faults mentioned in the literature, with Quaternary and geodetic slip rates reported for 38 and 26 faults respectively, and earthquake history reported for 39 faults. All data are accessible for viewing and download via http://www.geo.uni-tuebingen.de/faults/. This work has implications for seismic hazard studies in central Asia as it summarizes important fault parameters, and can reduce earthquake risk by enhancing public access to information. It also allows scientists and hazard assessment teams to identify structures and regions where data gaps exist and future investigations are needed.

  16. Late Quaternary history of the Atacama Desert

    Science.gov (United States)

    Latorre, Claudio; Betancourt, Julio L.; Rech, Jason A.; Quade, Jay; Holmgren, Camille; Placzek, Christa; Maldonado, Antonio; Vuille, Mathias; Rylander, Kate A.

    2005-01-01

    Of the major subtropical deserts found in the Southern Hemisphere, the Atacama Desert is the driest. Throughout the Quaternary, the most pervasive climatic influence on the desert has been millennial-scale changes in the frequency and seasonality of the scant rainfall, and associated shifts in plant and animal distributions with elevation along the eastern margin of the desert. Over the past six years, we have mapped modern vegetation gradients and developed a number of palaeoenvironmental records, including vegetation histories from fossil rodent middens, groundwater levels from wetland (spring) deposits, and lake levels from shoreline evidence, along a 1200-kilometre transect (16–26°S) in the Atacama Desert. A strength of this palaeoclimate transect has been the ability to apply the same methodologies across broad elevational, latitudinal, climatic, vegetation and hydrological gradients. We are using this transect to reconstruct the histories of key components of the South American tropical (summer) and extratropical (winter) rainfall belts, precisely at those elevations where average annual rainfall wanes to zero. The focus has been on the transition from sparse, shrubby vegetation (known as the prepuna) into absolute desert, an expansive hyperarid terrain that extends from just above the coastal fog zone (approximately 800 metres) to more than 3500 metres in the most arid sectors in the southern Atacama.

  17. Quaternary Magmatism in the Cascades - Geologic Perspectives

    Science.gov (United States)

    Hildreth, Wes

    2007-01-01

    Foreward The Cascade magmatic arc is a belt of Quaternary volcanoes that extends 1,250 km from Lassen Peak in northern California to Meager Mountain in Canada, above the subduction zone where the Juan de Fuca Plate plunges beneath the North American Plate. This Professional Paper presents a synthesis of the entire volcanic arc, addressing all 2,300 known Quaternary volcanoes, not just the 30 or so visually prominent peaks that comprise the volcanic skyline. Study of Cascade volcanoes goes back to the geological explorers of the late 19th century and the seminal investigations of Howel Williams in the 1920s and 1930s. However, major progress and application of modern scientific methods and instrumentation began only in the 1970s with the advent of systematic geological, geophysical, and geochemical studies of the entire arc. Initial stimulus from the USGS Geothermal Research Program was enhanced by the USGS Volcano Hazards Program following the 1980 eruption of Mount St. Helens. Together, these two USGS Programs have provided more than three decades of stable funding, staffing, and analytical support. This Professional Paper summarizes the resultant USGS data sets and integrates them with the parallel contributions of other investigators. The product is based upon an all-encompassing and definitive geological database, including chemical and isotopic analyses to characterize the rocks and geochronology to provide the critical time constraints. Until now, this massive amount of data has not been summarized, and a systematic and uniform interpretation firmly grounded in geological fact has been lacking. Herein lies the primary utility of this Cascade volume. It not only will be the mandatory starting point for new workers, but also will provide essential geological context to broaden the perspectives of current investigators of specific Cascade volcanoes. Wes Hildreth's insightful understanding of volcanic processes and his uncompromising scientific integrity make him

  18. Landward-advancing Quaternary eolianites of Bermuda

    Science.gov (United States)

    Rowe, Mark P.; Bristow, Charlie S.

    2015-12-01

    The landscape of Bermuda is dominated by Quaternary carbonate cemented dunes, or "eolianites", which form the islands' topography. Sections through the dunes are revealed in extensive natural and man-made rock faces, which expose the dune stratigraphy as well as the preserved morphology. An analysis of 3751 foreset measurements confirms the conclusion reached by earlier researchers that Bermuda's dunes advanced sub-perpendicularly to the coast in a landward direction away from source beaches. Dune orientation, being multi-directional, is not consistent with northeast net sand transportation predicted by a drift potential analysis of modern wind data. The putative predisposition of Bermuda's carbonate dunes to rapid cementation is supposed to have curtailed their landward advance such that younger dunes developed as static ridges at the seaward margin of their lithified predecessors. Geological mapping has revealed, however, that in many cases young dunes did advance inland onto interior terrain, overstepping older dune ridges. Molds of large trees, preserved within the dunes, and a sharp contact of steep slip-face dune foresets on palaeosols evoke the encroachment of landward-advancing precipitation ridges into a forested landscape. The internal structure of the dunes, featuring thick sets of slip-face foresets truncated by sub-horizontal planar bounding surfaces, uphold the ascendancy of sand transportation processes over those of sand retention and vertical accretion. Although meteoric cementation was responsible for the ultimate preservation of eolianite ridges which dominate Bermuda's landscape, it took effect too slowly to influence the behaviour of the carbonate dunes at the time of their emplacement.

  19. Synthesis, characterization, and bioactivity of rosin quaternary ammonium salt derivatives

    Directory of Open Access Journals (Sweden)

    Tao Liang

    2013-02-01

    Full Text Available Two series of rosin quaternary ammonium salts (QAS were synthesized using the same path. The structure of the target products was characterized by HPLC, MS, IR, and 1HNMR, and the bioactivity was determined by filter paper method using Trametes versicolor (white-rot fungus and Gloeophyllum trabeum (brown-rot fungus, which are two kinds of general wood decay fungi in nature. The results showed that all compounds tested had a satisfactory anti-fungal effect at the molarity of 0.025 mmol/mL. Hereinto, acrylpimaric Gemini QAS had better bioactivity than dehydrogenated or tetrahydrogenated rosin QAS against Trametes versicolor. To this fungus, quaternary ammonium groups, which wraps up the membrane of microorganism and disrupts the balance in cell membrane, plays the leading role for its bioactivity. To Gloeophyllum trabeum, the inhibition activity of acrylpimaric QAS and dehydrogenated rosin QAS are almost at the same level and larger than tetrahydrogenated rosin QAS, so we conclude that both quaternary ammonium group and aromatic group play important roles. Compared with dodecyl dimethyl benzyl ammonium chloride (1227, which is a commercially available quaternary ammonium salt type fungicide, acrylpimaric acid quaternary ammonium salts have approximate bioactivity against Gloeophyllum trabeum. In conclusion, rosin derivatives with functional groups would do well in wood preservative applications.

  20. Quaternary profiles of Gorleben 1 and 2 shafts

    International Nuclear Information System (INIS)

    To investigate the Gorleben salt dome underground, work on the sinking of the Gorleben 1 and 2 shafts was begun on 17 March 1986 and 10 November 1986, respectively. The ground around the shafts was frozen to prevent entry of groundwater into the excavation. In the meantime, both shafts have reached the top of the salt dome. The Quaternary sequence is about 156 m thick in the 1 shaft and about 173 m thick in the 2 shaft. Additionally, Quaternary material was found in the cap rock. The shafts were mapped from top to bottom and a large number of samples were taken. Analysis of the sediment and paleontological samples has not yet been completed. First investigation results show that the sequence includes strata from the pre-Elsterian Quaternary to the early Holocene. Simplified profiles of shafts 1 and 2 show the stratigraphy of the Quaternary strata. Additionally, the base of the Quaternary and the surface of the Lauenburger Ton (Lauenburg clay) are represented separately. (orig.)

  1. Absolute age determination of quaternary fault and formation

    International Nuclear Information System (INIS)

    The annual ('01-'01) objective of this project is to data the fault activity for the presumed quaternary fault zones to the western part of the Ulsam fault system and southeastern coastal area near the Wolseong Nuclear Power Plant. Rb-Sr, K-Ar, OSL, C-14 and U-series disequilibrium methods were applied to the fault rocks, organic matter and quaternary formations collected from the Pyeonghae, Bogyeongsa, Yugyeri, Byegkye, Gacheon-1 and Joil outcrops of the Yangsan fault system, the Baenaegol outcrop of the Moryang fault system, the Susyongji(Madong-2), Singye, Hwalseongri, Ipsil and Wonwonsa outcrops of the Ulsan fault system and from quaternary marine terraces (Oryoo and Kwangseong sites) in the southeastern coastal area. The experimental procedure of the OSL SAR protocol was reexamined to get more reliable dating results

  2. Quaternary evolution of the Caravelas strandplain - Southern Bahia State - Brazil

    Directory of Open Access Journals (Sweden)

    Andrade Ana C.S.

    2003-01-01

    Full Text Available An evolutionary model is proposed for the Caravelas strandplain. The model encompasses integration of: (i mapping of Quaternary deposits, (ii cartography of beach-ridge alignments and their truncations, (iii relative sea-level history, (iv development history of the Abrolhos coral reefs, (v vibra-coring and (vi C14 dating of Quaternary deposits. Seven major evolutionary stages were identified. These stages show that the strandplain has had its Quaternary evolution strongly controlled by relative sea-level changes. In addition, the development of the Abrolhos coral reefs has also played an important role in dispersion and accumulation of sediments along the coastline, causing localized inversion in longshore sediment transport.

  3. Quaternary naltrexone reverses radiogenic and morphine-induced locomotor hyperactivity

    Energy Technology Data Exchange (ETDEWEB)

    Mickley, G.A.; Stevens, K.E.; Galbraith, J.A.; White, G.A.; Gibbs, G.L.

    1984-04-01

    The present study attempted to determine the relative role of the peripheral and central nervous system in the production of morphine-induced or radiation-induced locomotor hyperactivity of the mouse. Toward this end, we used a quaternary derivative of an opiate antagonist (naltrexone methobromide), which presumably does not cross the blood-brain barrier. Quaternary naltrexone was used to challenge the stereotypic locomotor response observed in these mice after either an i.p. injection of morphine or exposure to 1500 rads /sup 60/Co. The quaternary derivative of naltrexone reversed the locomotor hyperactivity normally observed in the C57BL/6J mouse after an injection of morphine. It also significantly attenuated radiation-induced locomotion. The data reported here support the hypothesis of endorphin involvement in radiation-induced and radiogenic behaviors. However, these conclusions are contingent upon further research which more fully evaluates naltrexone methobromide's capacity to cross the blood-brain barrier.

  4. Ternary and quaternary antimonide devices for thermophotovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Hitchcock, C.W.; Gutmann, R.J.; Ehsani, H.; Bhat, I.B. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Integrated Electronics and Electronics Manufacturing; Wang, C.A. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Freeman, M.J.; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

    1998-06-01

    Thermophotovoltaic (TPV) devices have been fabricated using epitaxial ternary and quaternary layers grown on GaSb substrates. GaInSb ternary devices were grown by metalorganic vapor phase epitaxy (MOVPE) with buffer layers to accommodate the lattice mismatch, and GaInAsSb lattice-matched quaternaries were grown by MOVPE and by liquid phase epitaxy (LPE). Improved devices are obtained when optical absorption occurs in the p-layer due to the longer minority carrier diffusion length. Thick emitter p/n devices are limited by surface recombination, with highest quantum efficiency and lowest dark current being achieved with epitaxially grown surface passivation layers on lattice-matched MOVPE quaternaries. Thin emitter/thick base n/p devices are very promising, but require improved shallow high-quality n-type ohmic contacts.

  5. Origin of Quaternary Red Clay of Southern Anhui Province

    Institute of Scientific and Technical Information of China (English)

    HUXUEFENG; YUANGUODONG; 等

    1998-01-01

    The particle-size distribution,heavy mineral constituents and rare earth elements(REE) characteristics of the Quaternary red clay of southern Anhui Province were studied to explore the origin of the clay.The results showed that the clay had some properties of areolian deposits,which could be compared with,those of the loess in North China ;and its chondrite-normalized curves of REE were similar to those of the Xiashu loess implying tha they shared the same orighin.It was concluded in combination with the results rported by other researchers that the Quaternary red clay of southern Anhui Province originated from aolian deposts, and this could reveal the cycles of warm and cold climates in the area during the Quaternary period.

  6. Classification of quaternary Hermitian self-dual codes of length 20

    OpenAIRE

    Harada, Masaaki; Munemasa, Akihiro

    2010-01-01

    A classification of quaternary Hermitian self-dual codes of length 20 is given. Using this classification, a classification of extremal quaternary Hermitian self-dual codes of length 22 is also given.

  7. Antibacterial activity of reactive quaternary ammonium compounds in solution and in nonleachable coatings

    NARCIS (Netherlands)

    Gozzelino, G.; Romero Tobar, D.E.; Chaitiemwong, N.; Hazeleger, W.C.; Beumer, R.R.

    2011-01-01

    Antibacterial polymers suitable for coating applications without leaching of the biocidal component have been obtained by UV copolymerization of acrylic resins with acrylic monomers containing quaternary ammonium moieties. Suitable reactive biocides, based on quaternary ammonium monomers (QAMs), end

  8. Quaternary Structure Analyses of an Essential Oligomeric Enzyme.

    Science.gov (United States)

    Soares da Costa, Tatiana P; Christensen, Janni B; Desbois, Sebastien; Gordon, Shane E; Gupta, Ruchi; Hogan, Campbell J; Nelson, Tao G; Downton, Matthew T; Gardhi, Chamodi K; Abbott, Belinda M; Wagner, John; Panjikar, Santosh; Perugini, Matthew A

    2015-01-01

    Here, we review recent studies aimed at defining the importance of quaternary structure to a model oligomeric enzyme, dihydrodipicolinate synthase. This will illustrate the complementary and synergistic outcomes of coupling the techniques of analytical ultracentrifugation with enzyme kinetics, in vitro mutagenesis, macromolecular crystallography, small angle X-ray scattering, and molecular dynamics simulations, to demonstrate the role of subunit self-association in facilitating protein dynamics and enzyme function. This multitechnique approach has yielded new insights into the molecular evolution of protein quaternary structure. PMID:26412653

  9. Significant differences in late Quaternary bedrock erosion and transport

    DEFF Research Database (Denmark)

    Andrews, John; Bjørk, Anders Anker; Eberl, Dennis;

    2015-01-01

    We use quantitative X-ray diffraction to determine the mineralogy of late Quaternary marine sediments from the West and East Greenland shelves offshore from early Tertiary basalt outcrops. Despite the similar basalt outcrop area (60 000–70 000 km2), there are significant differences between East...... and West Greenland sediments in the fraction of minerals (e.g. pyroxene) sourced from the basalt outcrops. We demonstrate the differences in the mineralogy between East and West Greenland marine sediments on three scales: (1) modern day, (2) late Quaternary inputs and (3) detailed down-core variations...

  10. Electron paramagnetic resonance: A new method of quaternary dating

    International Nuclear Information System (INIS)

    Significant progress has occurred in the last years in quaternary geochronology. One of this is the emergence of a new dating approach, the Electron Spin Resonance Method. The aim of this paper is to briefly review the method and discuss some aspects of the work at CBPF. (Author)

  11. Preparation of quaternary pyridinium salts as possible proton conductors

    Czech Academy of Sciences Publication Activity Database

    Urban, Jiří; Havlíček, D.; Krajbich, J.

    2015-01-01

    Roč. 69, č. 3 (2015), s. 448-455. ISSN 0366-6352 Grant ostatní: GA MŠk(CZ) MSM0021620857 Institutional support: RVO:61388955 Keywords : quaternary pyridinium salts * synthesis * structural analysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.468, year: 2014

  12. Comparative analyses of quaternary arrangements in homo-oligomeric proteins in superfamilies: Functional implications.

    Science.gov (United States)

    Sudha, Govindarajan; Srinivasan, Narayanaswamy

    2016-09-01

    A comprehensive analysis of the quaternary features of distantly related homo-oligomeric proteins is the focus of the current study. This study has been performed at the levels of quaternary state, symmetry, and quaternary structure. Quaternary state and quaternary structure refers to the number of subunits and spatial arrangements of subunits, respectively. Using a large dataset of available 3D structures of biologically relevant assemblies, we show that only 53% of the distantly related homo-oligomeric proteins have the same quaternary state. Considering these homologous homo-oligomers with the same quaternary state, conservation of quaternary structures is observed only in 38% of the pairs. In 36% of the pairs of distantly related homo-oligomers with different quaternary states the larger assembly in a pair shows high structural similarity with the entire quaternary structure of the related protein with lower quaternary state and it is referred as "Russian doll effect." The differences in quaternary state and structure have been suggested to contribute to the functional diversity. Detailed investigations show that even though the gross functions of many distantly related homo-oligomers are the same, finer level differences in molecular functions are manifested by differences in quaternary states and structures. Comparison of structures of biological assemblies in distantly and closely related homo-oligomeric proteins throughout the study differentiates the effects of sequence divergence on the quaternary structures and function. Knowledge inferred from this study can provide insights for improved protein structure classification and function prediction of homo-oligomers. Proteins 2016; 84:1190-1202. © 2016 Wiley Periodicals, Inc. PMID:27177429

  13. Mapping a buried Quaternary valley and pre-Quaternary faults through seismic methods in Copenhagen, Denmark.

    Science.gov (United States)

    Martinez, Kerim; Alfredo Mendoza, Jose; Henrik, Olsen

    2010-05-01

    Limited knowledge of the subsurface geology motivates the use of geophysical techniques before large engineering projects are conducted. These applications are normally restricted to satisfy the project aims, like mapping the near surface sediments, unconsolidated rocks and/or geological structures that may affect the construction locally. However, the applications can also contribute to the general knowledge of the regional geology around the location of interest. This report highlights the mapping of a buried Quaternary valley and identification of regional faults by a reflection and refraction seismic survey performed in Copenhagen. A 13.9 Km seismic survey was carried out at Copenhagen city along six crooked lines in order to determine the velocity fields in the near subsurface segment of a planned metro line and reflection patterns in deeper levels. The aim of the survey was to collect information needed for designing the underground metro. In particular it was sought to map the interface between Quaternary sedimentary layers of clay, till and sand, and the underlying layers of Palaeogene limestone found between 7 and 40 m below the ground surface. The data acquisition was carried out using a 192 channels array, receiver groups with 5 m spacing and a Vibroseis as a source at 5 m spacing following a roll along technique to complete the survey spreads. The urban environment demanded extensive survey planning including traffic control, notifications to residents and a fluent coordination with municipal authorities in order to minimize disturbances and ensure data acquisition. The reflection data was processed under a conventional scheme and the refraction data was interpreted using a non-linear traveltime tomography algorithm. The reflection results indicate the presence of faults oriented NW-SE to NNW-SSE affecting the limestone sequences. The faults may be associated to the Sorgenfrei-Tornquist Zone at the transition between the Danish Basin and the Baltic

  14. Studies on a Cationically Modified Quaternary Ammonium Salt of Lignin

    Institute of Scientific and Technical Information of China (English)

    YANG Ai-li; JIANG Wen-ju

    2007-01-01

    A new quaternary ammonium salt monomer was synthesized and a quaternary amination of lignin( noted as QL),with the monomer was carried out by grafting copolymerization. The products were characterized by Fourier Transform Infrared spectroscopy(FTIR). The experimental results indicate that the yield of the monomer was 99.06%, and the conversion of the monomer and the grafting yield of QL were 93.69% and 185.78%, respectively. The feasibility of QL as the fiocculant to be applied in color removal of five artificial dyes, eriochrome black T( dye A), gongo red( dye B), direct fast black G (dye C), cuprofix blue green B (dye D), and acid black ATT (dye E) was examined.Results show that QL exhibits the favorable flocculation performance and high stability.

  15. Community ecology in a changing environment: Perspectives from the Quaternary

    Science.gov (United States)

    Jackson, Stephen T.; Blois, Jessica L.

    2015-04-01

    Community ecology and paleoecology are both concerned with the composition and structure of biotic assemblages but are largely disconnected. Community ecology focuses on existing species assemblages and recently has begun to integrate history (phylogeny and continental or intercontinental dispersal) to constrain community processes. This division has left a "missing middle": Ecological and environmental processes occurring on timescales from decades to millennia are not yet fully incorporated into community ecology. Quaternary paleoecology has a wealth of data documenting ecological dynamics at these timescales, and both fields can benefit from greater interaction and articulation. We discuss ecological insights revealed by Quaternary terrestrial records, suggest foundations for bridging between the disciplines, and identify topics where the disciplines can engage to mutual benefit.

  16. Control of Quaternary sea-level changes on gas seeps

    OpenAIRE

    Riboulot, Vincent; Thomas, Yannick; Berné, Serge,; Jouet, Gwénaël; Cattaneo, Antonio

    2014-01-01

    Gas seeping to the seafloor through structures such as pockmarks may contribute significantly to the enrichment of atmospheric greenhouse gases and global warming. Gas seeps in the Gulf of Lions, Western Mediterranean, are cyclical, and pockmark " life " is governed both by sediment accumulation on the continental margin and Quaternary climate changes. Three-dimensional seismic data, correlated to multi-proxy analysis of a deep borehole, have shown that these pockmarks are associated with obl...

  17. Session Introduction: Global correlation on late Quaternary paleovalley systems

    OpenAIRE

    Cohen, K.M.; Amorosi, A; Busschers, F.S.; Hori, K.; Tanabe, S.

    2015-01-01

    All around the world, paleovalley systems have trapped great amounts of deposits and hold a quite complete Late Quaternary record. Uniquely, these records directly interlink the shelf marine with the hinterland fluvial realms. In the vicinity of ice sheets, in similar ways, paleovalleys interlink the glacial record with the non-glacial domain. Considerable advances have been made in their study over the past decades, and many case well-dated and well-mapped case studies are now available. The...

  18. Pleistocene glaciation of the Mediterranean mountains, Quaternary Newsletter, 131

    OpenAIRE

    Adamson, K. R., Woodward, J. C. and Hughes, P. D.

    2013-01-01

    There is extensive evidence of Pleistocene glaciation across many mountainous regions in the Mediterranean. Research into the glacial record began over a century ago, but the application of radiometric dating techniques over the last few decades has allowed us to develop more robust geochronologies. It is now established that ice caps and valley glaciers developed on multiple occasions during the Quaternary during Marine Isotope Stages 14, 12, 10, 8, 6, 5d-2 and the Younger Dryas. This review...

  19. Intercalation of quaternary ammonium epoxide into montmorillonite structure

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena; Šabata, Stanislav

    Beijing : Chinese Vacuum Society, 2010. s. 109. [International Vacuum Congress /18./, International Conference on Nanoscience and Technology, International Conference on Solid Surfaces /14./, Vacuum and Surface Sciences Conference of Asia and Australia. 23.08.2010-27.08.2010, Beijing] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40720504 Keywords : montmorillonite * quaternary ammonium epoxide * intercalation Subject RIV: JI - Composite Materials

  20. Development of antibacterial quaternary ammonium silane coatings on polyurethane catheters

    Czech Academy of Sciences Publication Activity Database

    Zanini, S.; Polissi, A.; Maccagni, E.A.; Dell'Orto, E.C.; Liberatore, Chiara; Riccardi, C.

    2015-01-01

    Roč. 451, Aug (2015), 78-84. ISSN 0021-9797 R&D Projects: GA MŠk EE2.3.20.0143 Grant ostatní: OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : plasma-induced graft-polymerization * acrylic acid * ATR/FTIR * AFM * quaternary ammonium silane * Escherichia coli Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.368, year: 2014

  1. Quaternary fauna of bats in Spain: Paleoecologic and biogeographic interest

    OpenAIRE

    Sevilla, Paloma

    1989-01-01

    The study of fossil bat material collected in Quaternary localities in Spain has yielded interesting information on the characteristics of this fauna during the Pleistocene and Holocene in Spain. Out of the 25 species of Chiroptera actually living in Spain, 15 have been detected from the Middle Pleistocene onwards: Rhinolophus ferrumequinum, R. euryale, R. mehelyi, R. hipposideros, Myotis myotis, M. bechsteini, M. nattereri, M. emarginatus, Plecotus austriacus, Eptesicus ser...

  2. Multiple sources of alkanes in Quaternary oceanic sediment of Antarctica

    Science.gov (United States)

    Kvenvolden, K.A.; Rapp, J.B.; Golan-Bac, M.; Hostettler, F.D.

    1987-01-01

    Normal alkanes (n-C13n-C36), isoprenoid hydrocarbons (i-C15, i-C16, i-C18, i-C19, and i-C20) triterpanes (C27C32), and (C27C29) are present in low concentrations offshore Antarctica in near-surface, Quaternary sediment of the Wilkes Land continental margin and of the western Ross Sea. The distributions of these hydrocarbons are interpreted relative to possible sources and processes. The hydrocarbons appear to be mixtures of primary and recycled material from marine and terrigenous sources. The n-alkanes are most abundant and are characterized by two distinct populations, one of probable marine origin and the other likely from terrigenous, vascular plant sources. Because the continent of Antarctica today is devoid of higher plants, the plant-derived hydrocarbons in these offshore sediments probably came from wind-blown material and recycled Antarctic sediment that contains land-plant remains from an earlier period of time. Isoprenoid hydrocarbons are partially recycled and mainly of marine origin; the dominance of pristane over phytane suggests oxic paleoenvironmental conditions. Both modern and ancient triterpanes and steranes are present, and the distribution of these indicates a mixture of primary and recycled bacterial, algal, and possible higher-plant materials. Although the sampled sediments were deposited during the Quaternary, they apparently contain a significant component of hydrocarbons of pre-Quaternary age. ?? 1987.

  3. Anticholinesterase inhibitory activity of quaternary alkaloids from Tinospora crispa.

    Science.gov (United States)

    Yusoff, Mashitah; Hamid, Hazrulrizawati; Houghton, Peter

    2014-01-01

    Quaternary alkaloids are the major alkaloids isolated from Tinospora species. A previous study pointed to the necessary presence of quaternary nitrogens for strong acetylcholinesterase (AChE) inhibitory activity in such alkaloids. Repeated column chromatography of the vine of Tinospora crispa extract led to the isolation of one new protoberberine alkaloid, 4,13-dihydroxy-2,8,9-trimethoxydibenzo[a,g]quinolizinium (1), along with six known alkaloids-dihydrodiscretamine (2), columbamine (3), magnoflorine (4), N-formylannonaine (5), N-formylnornuciferine (6), and N-trans-feruloyltyramine (7). The seven compounds were isolated and structurally elucidated by spectroscopic analysis. Two known alkaloids, namely, dihydrodiscretamine and columbamine are reported for the first time for this plant. The compounds were tested for AChE inhibitory activity using Ellman's method. In the AChE inhibition assay, only columbamine (3) showed strong activity with IC50 48.1 µM. The structure-activity relationships derived from these results suggest that the quaternary nitrogen in the skeleton has some effect, but that a high degree of methoxylation is more important for acetylcholinesterase inhibition. PMID:24448061

  4. Anticholinesterase Inhibitory Activity of Quaternary Alkaloids from Tinospora crispa

    Directory of Open Access Journals (Sweden)

    Mashitah Yusoff

    2014-01-01

    Full Text Available Quaternary alkaloids are the major alkaloids isolated from Tinospora species. A previous study pointed to the necessary presence of quaternary nitrogens for strong acetylcholinesterase (AChE inhibitory activity in such alkaloids. Repeated column chromatography of the vine of Tinospora crispa extract led to the isolation of one new protoberberine alkaloid, 4,13-dihydroxy-2,8,9-trimethoxydibenzo[a,g]quinolizinium (1, along with six known alkaloids—dihydrodiscretamine (2, columbamine (3, magnoflorine (4, N-formylannonaine (5, N-formylnornuciferine (6, and N-trans-feruloyltyramine (7. The seven compounds were isolated and structurally elucidated by spectroscopic analysis. Two known alkaloids, namely, dihydrodiscretamine and columbamine are reported for the first time for this plant. The compounds were tested for AChE inhibitory activity using Ellman’s method. In the AChE inhibition assay, only columbamine (3 showed strong activity with IC50 48.1 µM. The structure–activity relationships derived from these results suggest that the quaternary nitrogen in the skeleton has some effect, but that a high degree of methoxylation is more important for acetylcholinesterase inhibition.

  5. Ecological impacts of the late Quaternary megaherbivore extinctions.

    Science.gov (United States)

    Gill, Jacquelyn L

    2014-03-01

    As a result of the late Quaternary megafaunal extinctions (50,000-10,000 before present (BP)), most continents today are depauperate of megaherbivores. These extinctions were time-transgressive, size- and taxonomically selective, and were caused by climate change, human hunting, or both. The surviving megaherbivores often act as ecological keystones, which was likely true in the past. In spite of this and extensive research on the causes of the Late Quaternary Extinctions, the long-term ecological consequences of the loss of the Pleistocene megafauna remained unknown until recently, due to difficulties in linking changes in flora and fauna in paleorecords. The quantification of Sporormiella and other dung fungi have recently allowed for explicit tests of the ecological consequences of megafaunal extirpations in the fossil pollen record. In this paper, I review the impacts of the loss of keystone megaherbivores on vegetation in several paleorecords. A growing number of studies support the hypothesis that the loss of the Pleistocene megafauna resulted in cascading effects on plant community composition, vegetation structure and ecosystem function, including increased fire activity, novel communities and shifts in biomes. Holocene biota thus exist outside the broader evolutionary context of the Cenozoic, and the Late Quaternary Extinctions represent a regime shift for surviving plant and animal species. PMID:24649488

  6. Radiation-curable polymers bearing quaternary nitrogen groups

    International Nuclear Information System (INIS)

    Polymers, such as butadiene copolymers and isoprene copolymers, having pendant unsaturated tetra-aliphatic quaternary nitrogen moieties, such as those derived from acrylic esters and acrylamides are useful as water-soluble or inherently water-dispersible curable coatings such as protective and/or decorative coatings, paper coatings, textile fiber coatings, printing plates, photocurable imagable materials useful as photo-resists, lithographic plates, etc., and the like. Such coatings are curable with light, with high energy radiation and with heat in the presence of free radical catalysts to form insoluble, crosslinked coatings

  7. Quaternary phosphorites off the southeast coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Michard, A.; Naqvi, S.W.A.; Boettcher, M.E.; Krishnaswamy, R.; Thamban, M.; Natarajan, R.; Borole, D.V.

    off the southeast coast of India. The purpose of this paper is to report an integrated study using petrologi- cal, mineralogical, chemical, radiogenic and stable isotope composition of the Quaternary phosphorites Ž. off Chennai, southeast coast... of the phosphorites. Polished sections of the phosphorites show grain-supported texture and dense phosphate Ž.Fig. 2. Phosphorites and associated sediment constituents in a gravity core SK148r1 at 192 m depth of the shelf margin depression. ()V.P. Rao et al...

  8. Aluminum-silicates flotation with quaternary ammonium salts

    Institute of Scientific and Technical Information of China (English)

    王毓华; 胡岳华; 陈湘清

    2003-01-01

    The zeta potential measurements show that the flotation separation of diaspore from kaolinite, illite and pyrophyllite could be achieved in the range of pH 46.5 with cationic collectors. A special quaternary ammonium salts(DTAL) shows better selectivity than that the dodecyl amine(DDA) does for the flotation of three silicates. The closed-circuit flotation results show that the reverse flotation de-silicate can be achieved with DTAL as collector, a new inorganic reagent(SFL) as depressant and MIBC as frother to obtain a bauxite concentrate m(Al2O3)/m(SiO2)>10, Al2O3 recovery>86%).

  9. Late Quaternary record of pteropod preservation from the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sijinkumar, A.V.; Nath, B.N.; Guptha, M.V.S

    ., vol.275(1-4); 2010; 221-229 Late Quaternary record of pteropod preservation from the Andaman Sea A.V.Sijinkumar a,b , *, B. Nagender Nath a , M.V.S. Guptha a,c a National Institute of Oceanography (Council of Scientific and Industrial Research... to the western 3 part. Aragonite preservation in the eastern part of the northern Indian Ocean, Bay of Bengal (BOB) and the Andaman Sea, and changes therein through time, are virtually unknown. The world’s highest physical and chemical erosion rates...

  10. Quaternary Salts of Chitosan: History, Antimicrobial Features, and Prospects

    Directory of Open Access Journals (Sweden)

    Douglas de Britto

    2011-01-01

    Full Text Available Recently, increasing attention has been paid to water-soluble derivatives of chitosan at its applications. The chemical characteristics and the antimicrobial properties of these salts can play significant role in pharmacological and food areas mainly as carriers for drug delivery systems and as antimicrobial packaging materials. In the current paper, a historical sequence of the main preparative methods, physical chemistry aspects, and antimicrobial activity of chitosan quaternized derivatives are presented and briefly discussed. In general, the results indicated that the quaternary derivatives had better inhibitory effects than the unmodified chitosan.

  11. Quaternary extensional and compressional tectonics revealed from Quaternary landforms along Kosi River valley, outer Kumaun Lesser Himalaya, Uttarakhand

    Science.gov (United States)

    Luirei, Khayingshing; Bhakuni, S. S.; Kothyari, Girish Ch.; Tripathi, Kavita; Pant, P. D.

    2016-04-01

    A portion of the Kosi River in the outer Kumaun Lesser Himalaya is characterized by wide river course situated south of the Ramgarh Thrust, where huge thickness (~200 m) of the landslide deposits and two to three levels of unpaired fan terraces are present. Brittle normal faults, suggesting extensional tectonics, are recognized in the Quaternary deposits and bedrocks as further supported by surface morphology. Trending E-W, these faults measure from 3 to 5 km in length and are traced as discontinuous linear mini-horst and fault scarps (sackungen) exposed due to cutting across by streams. Active normal faults have displaced the coarsely laminated debris fan deposits at two sites located 550 m apart. At one of the sites, the faults look like bookshelf faulting with the maximum displacement of ~2 m and rotation of the Quaternary boulders along the fault plane is observed. At another site, the maximum displacement measures about 0.60 cm. Thick mud units deposited due to blocking of the streams by landslides are observed within and above the fan deposit. Landslide debris fans and terrace landforms are widely developed; the highest level of fan is observed ~1240 m above mean sea level. At some places, the reworking of the debris fans by streams is characterized by thick laminated sand body. Along the South Almora Thrust and Ramgarh Thrust zones, the valleys are narrow and V-shaped where Quaternary deposits are sparse due to relatively rapid uplift across these thrusts. Along the South Almora Thrust zone, three to four levels of fluvial terraces are observed and have been incised by river exposing the bedrocks due to recent movement along the RT and SAT. Abandoned channel, tilted mud deposits, incised meandering, deep-cut V-shaped valleys and strath terraces indicate rapid uplift of the area. Thick mud sequences in the Quaternary columns indicate damming of streams. A ~10-km-long north-south trending transverse Garampani Fault has offset the Ramgarh Thrust producing

  12. Radiosensitization by quaternary salts of 5-nitroimidazole derivatives

    International Nuclear Information System (INIS)

    The radiosensitizing effects of five newly synthesized quaternary salts of 5-nitroimidazole derivatives on the survival of TC-SV40 mammalian cells were measured. The OER for TC-SV40 cells was 2.74. None of the derivatives showed radiosensitizing activity in aerobic conditions, while in hypoxia dose-modifying factors (DMF) at the concentration of 0.2 mmol dm-3 range from 1.52 to 1.03 in this order: unsubstituted pyridinium>carbamoyl pyridinium>trimethyl pyridinium>t-butyl pyridinium>imidazolium. This latter product at a concentration of 2 mmol dm-3 has a DMF of 1.64. Metronidazole gave a DMF at 0.2 mmol dm-3 of 1.35. Response-concentration dependences for the unsubstituted pyridinium 5-nitro-imidazole derivative and metronidazole (comparing charged and uncharged structures) showed the flattening response-concentration curve of quaternary compounds. The electron affinity was evaluated through the CNDO/S theoretical method, and an exponential relationship between these values and DMFs of the pyridinium derivatives was demonstrated. (author)

  13. European quaternary refugia: a factor in large carnivore extinction?

    Science.gov (United States)

    O'Regan, Hannah J.; Turner, Alan; Wilkinson, David M.

    2002-12-01

    The extinction of large carnivores in Europe during the Quaternary is reviewed and the potential role of glacial refugia in these extinctions is investigated using the VORTEX model for population viability analysis. A model was built for a medium sized big cat similar to the extinct Panthera gombaszoegensis utilising life history data from the modern jaguar Panthera onca. This approach highlighted the potential importance of glacial refugia in the extinction process. Even model refugia the size of the Italian peninsula did not guarantee persistence of a population over a 1000 yr time span, illustrating the role of chance in survival in such a refugium. An area the size of the largest Mediterranean island was unable to support a big cat population for a period of 1000 yr. The models also demonstrated the importance of inbreeding as a mechanism for extinction in refugia. It is suggested that repeated genetic bottlenecks during successive glaciations would tend to remove lethal recessive alleles from the population, increasing the probability of survival in refugia in subsequent glaciations. The history of extinction of large carnivores in the European Quaternary is interpreted in the light of these results.

  14. Modeling of alkyl quaternary ammonium cations intercalated into montmorillonite lattice

    International Nuclear Information System (INIS)

    Highlights: ► The modification of montmorillonites by three surfactants increases the basal spacing. ► The model proposed show a bilayer conformation for the surfactant ODTMA. ► The DODMA and TOMA surfactants adopt a paraffin type arrangement. ► Behavior of surfactants in interlayer space was confirmed by TGA and ATR analysis. - Abstract: The objective of this work was to study the conformation of the quaternary ammonium cations viz., octadecyl trimethyl ammonium (ODTMA), dioctadecyl dimethyl ammonium (DMDOA) and trioctadecyl methyl ammonium (TOMA) intercalated within montmorillonite. The modified montmorillonite was characterized by X-ray diffraction in small angle (SAXS), thermal analysis (TGA) and infrared spectroscopy of attenuated total reflection (ATR). The modification of organophilic montmorillonites by the three surfactants ODTMA, DMDOA and TOMA increases the basal spacing from their respective intercalated distances of 1.9 nm, 2.6 nm and 3.4 nm respectively. The increase in the spacing due to the basic organic modification was confirmed by the results of thermal analysis (TGA) and infrared spectroscopy (ATR), and also supported by theoretical calculations of longitudinal and transversal chain sizes of these alkyl quaternary ammonium cations

  15. Historical distribution of Sundaland's Dipterocarp rainforests at Quaternary glacial maxima.

    Science.gov (United States)

    Raes, Niels; Cannon, Charles H; Hijmans, Robert J; Piessens, Thomas; Saw, Leng Guan; van Welzen, Peter C; Slik, J W Ferry

    2014-11-25

    The extent of Dipterocarp rainforests on the emergent Sundaland landmass in Southeast Asia during Quaternary glaciations remains a key question. A better understanding of the biogeographic history of Sundaland could help explain current patterns of biodiversity and support the development of effective forest conservation strategies. Dipterocarpaceae trees dominate the rainforests of Sundaland, and their distributions serve as a proxy for rainforest extent. We used species distribution models (SDMs) of 317 Dipterocarp species to estimate the geographic extent of appropriate climatic conditions for rainforest on Sundaland at the last glacial maximum (LGM). The SDMs suggest that the climate of central Sundaland at the LGM was suitable to sustain Dipterocarp rainforest, and that the presence of a previously suggested transequatorial savannah corridor at that time is unlikely. Our findings are supported by palynologic evidence, dynamic vegetation models, extant mammal and termite communities, vascular plant fatty acid stable isotopic compositions, and stable carbon isotopic compositions of cave guano profiles. Although Dipterocarp species richness was generally lower at the LGM, areas of high species richness were mostly found off the current islands and on the emergent Sunda Shelf, indicating substantial species migration and mixing during the transitions between the Quaternary glacial maxima and warm periods such as the present. PMID:25385612

  16. Late-quaternary vegetational dynamics and community stability reconsidered

    Science.gov (United States)

    Delcourt, Paul A.; Delcourt, Hazel R.

    1983-03-01

    Defining the spatial and temporal limits of vegetational processes such as migration and invasion of established communities is a prerequisite to evaluating the degree of stability in plant communities through the late Quaternary. The interpretation of changes in boundaries of major vegetation types over the past 20,000 yr offers a complementary view to that provided by migration maps for particular plant taxa. North of approximately 43°N in eastern North America, continual vegetational disequilibrium has resulted from climatic change, soil development, and species migrations during postglacial times. Between 33° and 39°N, stable full-glacial vegetation was replaced by a relatively unstable vegetation during late-glacial climatic amelioration; stable interglacial vegetation developed there after about 9000 yr B.P. Late-Quaternary vegetation has been in dynamic equilibrium, with a relatively constant flora, south of 33°N on upland interfluves along the northern Gulf Coastal Plain, peninsular Florida, and west-central Mexico.

  17. Latest Quaternary stratigraphic framework of the Mississippi River delta region

    Science.gov (United States)

    Kulp, Mark; Howell, Paul; Adiau, Sandra; Penland, Shea; Kindinger, Jack; Williams, S. Jeffress

    2002-01-01

    Previous researchers separated the uppermost Quaternary stratigraphy of the Mississippi River delta region into two major lithofacies. The stratigraphically lower of these, "substratum," primarily consists of coarse-grained sediment deposited within lowstand-incised stream valleys. Relatively finer-grained "topstratum" overlies substratum; above interfluves, topstratum directly overlies weathered late Pleistocene sediments. However, the onshore to offshore distribution and architecture of these lithofacies was not well constrained. This study integrates published and unpublished lithostratigraphic data with high-resolution seismic profiles from the continental shelf to aid in mapping the regional distribution of major substratum deposits and thickness of topstratum sediments. A transgressive sand sheet commonly marks the base of the topstratum deposits, providing a stratigraphic marker to aid in regional lithostratigraphic correlations. Radiocarbondated deposits and boreholes tied to oxygen isotope chronologies provide chronostratigraphic control. Excellent correlation between these multiple datasets has been found to exist, enabling construction of regional isopachous and structural elevation maps and cross sections detailing elements of the Late Quaternary stratigraphy.

  18. Quaternary climate - Terrestrial Biosphere Interaction: amplifying or stabilizing?

    Science.gov (United States)

    Claussen, Martin

    2016-04-01

    According to the Gaia hypothesis, interaction between climate and biological processes tend to homeostatically maintain, on a global scale, conditions favourable for life. Does the idea of homeostatic interaction between terrestrial biosphere and climate hold for the Quaternary glacial - interglacial changes? Interpretation of palaeoclimate and palaeobotanic evidence by using climate and Earth system models yields an interesting picture. The synergy between the sea-ice albedo - climate feedback and the taiga-tundra - climate feedback is suggested to amplify the orbitally forced climatic precession. This effect seems to be strong at regional scale, but small at global scale. Various simulations indicate that biogeophysical processes amplify the difference of some 4 to 6 K in global mean temperature between glacial and interglacial climate by some 10 percent. The combined effect of biogeophysical and biogeochemical processes, i.e. processes with involve carbon stored in biomass and soil, is less clear. Theoretical studies suggest that in pre-industrial, interglacial climate, a reduction in boreal and extratropical forests tend to cool the climate and a reduction in tropical forest, to warm the climate. Recent estimates in changes in organic carbon stored under ice sheets and in permafrost point at the possibility that the sum of all terrestrial biogeochemical processes might almost "carbon neutral" to the climate system. If corroborated, this observation would favour the assumption of a dominance of biogeophysical processes amplifying orbitally forced Quaternary climate variations.

  19. Dating the Quaternary: progress in luminescence dating of sediments

    Science.gov (United States)

    Lian, Olav B.; Roberts, Richard G.

    2006-10-01

    Luminescence dating comprises a collection of numerical-age techniques that are among the most significant chronological tools currently used in Quaternary research. This paper briefly reviews the key historical developments in luminescence dating, from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight-exposed sediments. We describe the principles and practicalities of the various techniques commonly used in luminescence dating, including multiple-aliquot, single-aliquot and single-grain procedures, and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation (e.g., by means of component analysis and dose distribution methods in optical dating). The overview also introduces the other papers in this special issue of Quaternary Science Reviews, which address a selection of important issues in basic research, technique development and application of luminescence dating to critical questions in the geological and archaeological sciences, illustrated with examples from around the world and the last million years of Earth history.

  20. Quaternary seismo-tectonic activity of the Polochic Fault, Guatemala

    Science.gov (United States)

    Authemayou, Christine; Brocard, Gilles; Teyssier, Christian; Suski, Barbara; Cosenza, Beatriz; MoráN-Ical, Sergio; GonzáLez-VéLiz, Claussen Walther; Aguilar-Hengstenberg, Miguel Angel; Holliger, Klaus

    2012-07-01

    The Polochic-Motagua fault system is part of the sinistral transform boundary between the North American and Caribbean plates in Guatemala and the associated seismic activity poses a threat to ˜70% of the country's population. The aim of this study is to constrain the Late Quaternary activity of the Polochic fault by determining the active structure geometry and quantifying recent displacement rates as well as paleo-seismic events. Slip rates have been estimated from offsets of Quaternary volcanic markers and alluvial fan using in situ cosmogenic 36Cl exposure dating. Holocene left-lateral slip rate and Mid-Pleistocene vertical slip rate have been estimated to 4.8 ± 2.3 mm/y and 0.3 ± 0.06 mm/y, respectively, on the central part of the Polochic fault. The horizontal slip rate is within the range of longer-term geological slip rates and short-term GPS-based estimates. In addition, the non-negligible vertical motion participates in the uplift of the block north of the fault and seems to be a manifestation of the regional, far-field stress regime. We excavated the first trench for paleo-seismological study on the Polochic fault in which we distinguish four large paleo-seismic events since 17 ky during which the Polochic fault ruptured the ground surface.

  1. Quaternary history and contemporary patterns in a currently expanding species

    Directory of Open Access Journals (Sweden)

    Rousselet Jérôme

    2009-09-01

    Full Text Available Abstract Background Quaternary climatic oscillations had dramatic effects on species evolution. In northern latitudes, populations had to survive the coldest periods in refugial areas and recurrently colonized northern regions during interglacials. Such a history usually results in a loss of genetic diversity. Populations that did not experience glaciations, in contrast, probably maintained most of their ancestral genetic diversity. These characteristics dramatically affected the present-day distribution of genetic diversity and may influence the ability of species to cope with the current global changes. We conducted a range-wide study of mitochondrial genetic diversity in the pine processionary moth (Thaumetopoea pityocampa/T. wilkinsoni complex, Notodontidae, a forest pest occurring around the Mediterranean Basin and in southern Europe. This species is responding to the current climate change by rapid natural range expansion and can also be accidentally transported by humans. Our aim was to assess if Quaternary climatic oscillations had a different effect across the species' range and to determine if genetic footprints of contemporary processes can be identified in areas of recent introduction. Results We identified three main clades that were spatially structured. In most of Europe, the genetic diversity pattern was typical for species that experienced marked glaciation cycles. Except in refugia, European populations were characterized by the occurrence of one main haplotype and by a strong reduction in genetic diversity, which is expected in regions that were rapidly re-colonized when climatic conditions improved. In contrast, all other sub-clades around the Mediterranean Basin occurred in limited parts of the range and were strongly structured in space, as is expected in regions in which the impact of glaciations was limited. In such places, genetic diversity was retained in most populations, and almost all haplotypes were endemic. This

  2. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    The extensive Quaternary volcanism in the Payenia volcanic province, Mendoza, Argentina, is investigated in this study by major and trace element analyses, Sr, Nd, Hf and Pb-isotopic analyses and Zr-Hf isotope dilution data on samples from almost the entire province. The samples are mainly...... basalts from all the studied volcanic fields in Payenia is signs of lower crustal contamination indicating assimilation of, in some cases, large amounts of trace element depleted, mafic, plagioclase-bearing rocks. The northern Payenia is dominated by backarc basalts erupted between late Pliocene to late...... Pleistocene times. These basalts mark the end of a period of shallow subduction of the Nazca slab beneath the Payenia province and volcanism in the Nevado volcanic field apparently followed the downwarping slab in a north-northwest direction ending in the Northern Segment. The northern Payenia basalts are...

  3. Vibrational spectra and structure of bismuth based quaternary glasses

    International Nuclear Information System (INIS)

    Quaternary bismuthate glasses containing Li2O, ZnO and B2O3 have been prepared by melt quench technique and studied by density, DSC, IR and Raman spectroscopy. Raman and infrared spectroscopy have been employed to investigate the (75 - x)Bi2O3-xLi2O-10ZnO-15B2O3 glasses in order to obtain information about the competitive role of Bi2O3 and B2O3 in the formation of glass network. The increase of Bi2O3 content causes a progressive conversion of three- to four-fold coordinated boron. IR and Raman spectra show that these glasses are made up of [BiO3] pyramidal and [BiO6] octahedral units. The formation of Zn in tetrahedral coordination was observed

  4. Quaternary climate changes explain diversity among reptiles and amphibians

    DEFF Research Database (Denmark)

    Bastos Araujo, Miguel; Nogués-Bravo, David; Diniz-Filho, Alexandre F.;

    2008-01-01

    debated without reaching consensus. Here, we test the proposition that European species richness of reptiles and amphibians is driven by climate changes in the Quaternary. We find that climate stability between the Last Glacial Maximum (LGM) and the present day is a better predictor of species richness......It is widely believed that contemporary climate determines large-scale patterns of species richness. An alternative view proposes that species richness reflects biotic responses to historic climate changes. These competing "contemporary climate" vs "historic climate" hypotheses have been vigorously...... than contemporary climate; and that the 0°C isotherm of the LGM delimits the distributions of narrow-ranging species, whereas the current 0°C isotherm limits the distributions of wide-ranging species. Our analyses contradict previous studies of large-scale species richness patterns and support the view...

  5. The geological characteristics during the quaternary period around Japan island

    Energy Technology Data Exchange (ETDEWEB)

    Hagiwara, Shigeru [Chuo Kaihatsu Corp., Enterprises Promotion Bureau, Tokyo (Japan); Sakamoto, Yoshiaki; Ogawa, Hiromichi; Nakayama, Shinichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-11-01

    Radioactive wastes arising from radioisotope facilities and nuclear research facilities should be disposed of in the surface of the earth, the shallow underground, the adequate depth and the deep underground according to radioactivity concentrations, and should be managed during several hundreds years. The earth scientific phenomena observed in Japan island at present occurred continuously from the past, and the same phenomena at the future should occur in the similar factor. Therefore, for the purpose to get the fundamental data for the selection of disposal site, this report reviewed on the genesis and classification of the sediments, earth scientific phenomena observed in Japan island and the feature of each place (10 districts) concerning to the Quaternary period in the newest geological time unit. (author)

  6. Global Environments through the Quaternary – Exploring Environmental Change

    Directory of Open Access Journals (Sweden)

    Josie Rose Mills

    2013-07-01

    Full Text Available Born from a series of volumes titled Environmental Change, first printed in 1976, this book is the second edition of a revised history of the global environment published in 2013. It is the collaborative work of David Anderson, Andrew Goudie, and Adrian Parker, all experts in the field of geography, with Parker also having a background in anthropology. Global Environments through the Quaternary provides a general scientific guide to interpreting environmental change. It is aimed at a wide audience and has a full glossary of less well known terms for added clarity. It would be a good accompaniment to a geoarchaeology course or for those interested in the history of environmental fluctuation, with its particular strengths lying in the concise and accessible presentation of scientific data. This enables it to work well as a reference guide that can be used alongside more in-depth research as it provides a key knowledge base with which to formulate personal theories.

  7. Aggregation behavior of quaternary salt based cationic surfactants

    International Nuclear Information System (INIS)

    The aggregation behavior of pure cationic surfactants (quaternary salts) in water has been studied by electrical conductivity (at 293.15-333.15K), surface tension, dye solubilization and viscosity measurements (at 303.15K). Critical micelle concentrations (CMCs), degree of counter ion dissociation (β), aggregation number and sphere-to-rod transition for cationic surfactants are reported. Using law of mass action model, the thermodynamic parameters, viz. Gibbs energy (ΔGm-bar ), enthalpy (ΔHm-bar ) and entropy (ΔSm-bar ) were evaluated. The plots of differential conductivity (dk/dc)T,P, versus the total surfactant concentration enables us to determine the CMC values more precisely than the conventional method. Surfactants with longer hydrocarbon chain are adapted to rodlike micelle better than to a spherical micelle. The data are explained in terms of molecular characteristics of surfactants viz. nonpolar chain length, polar head group size and counter ion

  8. Antibacterial effect of composite resins containing quaternary ammonium polyethyleneimine nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Yudovin-Farber, Ira [Hebrew University of Jerusalem, Department of Medicinal Chemistry and Natural Products, School of Pharmacy, Faculty of Medicine (Israel); Beyth, Nurit; Weiss, Ervin I. [Hebrew University of Jerusalem, Department of Prosthodontics, Faculty of Dentistry (Israel); Domb, Abraham J., E-mail: avid@ekmd.huji.ac.i [Hebrew University of Jerusalem, Department of Medicinal Chemistry and Natural Products, School of Pharmacy, Faculty of Medicine (Israel)

    2010-02-15

    Quaternary ammonium polyethyleneimine (QA-PEI)-based nanoparticles were synthesized by crosslinking with dibromopentane followed by N-alkylation with various alkyl halides and further N-methylation with methyl iodide. Insoluble pyridinium-type particles were prepared by suspension polymerization of 4-vinyl pyridine followed by N-alkylation with alkyl halides. Polyamine-based nanoparticles embedded in restorative composite resin at 1% w/w were tested for antibacterial activity against Streptococcus mutans using direct contact test. Activity analysis revealed that the alkyl chain length of the QA-PEI nanoparticles plays a significant role in antibacterial activity of the reagent. The most potent compound was octyl-alkylated QA-PEI embedded in restorative composite resin at 1% w/w that totally inhibited S. mutans growth in 3-month-aged samples. This data indicates that restorative composite resin with antibacterial properties can be produced by the incorporation of QA-PEI nanoparticles.

  9. Expansion and contraction of Chinese deserts during the Quaternary

    Institute of Scientific and Technical Information of China (English)

    刘东生; 孙继敏

    2002-01-01

    Episodic dune formations during the Quaternary are found in many deserts of China.The causes of desert expansions on different time scales are not the same. Desert extension atabout 1.1 and 0.9 Ma ago were the response to the active tectonic movements, whereas the de-sert evolutions on the ten-thousand years time scale were the response to the orbital scale climaticchanges. Spatial scale studies on desert evolution indicate that desert margins shifted greatly dur-ing the last glacial maximum (LGM) and the Holocene optimum, its changing from 125°E of theLGM to 105°E of the climatic optimum. Historical desertification in the semiarid China is not a re-sponse to climate drought but largely associated with the human impacts (mainly over-cultivation)since about 2300 years ago, which leads to the reworking of the underlying LGM sands.

  10. The geological characteristics during the quaternary period around Japan island

    International Nuclear Information System (INIS)

    Radioactive wastes arising from radioisotope facilities and nuclear research facilities should be disposed of in the surface of the earth, the shallow underground, the adequate depth and the deep underground according to radioactivity concentrations, and should be managed during several hundreds years. The earth scientific phenomena observed in Japan island at present occurred continuously from the past, and the same phenomena at the future should occur in the similar factor. Therefore, for the purpose to get the fundamental data for the selection of disposal site, this report reviewed on the genesis and classification of the sediments, earth scientific phenomena observed in Japan island and the feature of each place (10 districts) concerning to the Quaternary period in the newest geological time unit. (author)

  11. Synthesis, characterization, and antifungal activity of novel quaternary chitosan derivatives.

    Science.gov (United States)

    Li, Rongchun; Guo, Zhanyong; Jiang, Pingan

    2010-09-01

    Three novel quaternary chitosan derivatives were successfully synthesized by reaction of chloracetyl chitosan (CACS) with pyridine (PACS), 4-(5-chloro-2-hydroxybenzylideneamino)-pyridine (CHPACS), and 4-(5-bromo-2-hydroxybenzylideneamino)-pyridine (BHPACS). The chemical structure of the prepared chitosan derivatives was confirmed by Fourier transform infrared (FT-IR) and (13)C nuclear magnetic resonance ((13)C NMR) and their antifungal activity against Cladosporium cucumerinum, Monilinia fructicola, Colletotrichum lagenarium, and Fusarium oxysporum was assessed. Comparing with the antifungal activity of chitosan, CACS, and PACS, CHPACS and BHPACS exhibited obviously better inhibitory effects, which should be related to the synergistic reaction of chitosan itself with the grafted 2-[4-(5-chloro-2-hydroxybenzylideneamino)-pyridyl]acetyl and 2-[4-(5-bromo-2-hydroxybenzylideneamino)-pyridyl]acetyl. PMID:20615498

  12. Quaternary glacial evolution in the Central Cantabrian Mountains (Northern Spain)

    Science.gov (United States)

    Serrano, E.; González-Trueba, J. J.; Pellitero, R.; González-García, M.; Gómez-Lende, M.

    2013-08-01

    The glacial evolution of the Cantabrian Mountains is not well known. Previous studies have focused on the extent of the glacial maximum and the presence of younger features in several massifs. Recently, efforts have been made to date glacial periods, particularly the glacial maximum. This work presents a reconstruction of the glacial evolution in the Cantabrian Mountains, providing data on the environmental characteristics and timing of the different stages from the Quaternary glacial maximum to the Little Ice Age. The study area covers 3000 km2 between the 4°58'W and 3°34'W and includes eleven massifs of the central area of the Cantabrian Mountains. The selected sectors have an Atlantic and Atlantic-Mediterranean transitional climate and include the highest massifs (above 2600 m) and low-altitude glacierised massifs (lower than 2000 m). Glacial extent and evolution have been reconstructed on the basis of detailed geomorphological and morphostratigraphic mapping. The equilibrium line altitude (palaeo-ELA) has been estimated for the different stages of each tongue. The ELA has been assessed by the AAR and modified Kurowski methods and altitude methods have been considered. A numerical chronological framework is proposed using 17 AMS radiocarbon and one OSL data obtained in lake and bog deposits from three massifs. Four main glacial stages have been differentiated, between 38,000 BP and the Little Ice Age. They correspond to different cold environments, and the number of glacial stages varies from one to four among the different massifs. Conclusions are analysed in the context of the Quaternary glacial evolution of other Iberian mountains.

  13. Book Review: The history of the Quaternary Research Association

    Science.gov (United States)

    Bowen, D. Q.

    2016-06-01

    This is a book that should be in the library of every member of the QRA as well as their institutions. This volume is a celebration of 50 years of the Quaternary Studies Field Group (1964), which was renamed the Quaternary Research Association (QRA) in 1969. What follows is a combination of a review with some further information based on the recollection of someone who was there. In examining the origins of the QSFG due credit is paid to Richard Hey and Richard West, but an inexplicable omission is the earlier discussion between Hey, Allan Straw and others during the field meeting of the Yorkshire Geological Society in September 1962 (Worsley, 2014). It is said that history is always written by the victors, or in modern parlance by those who write the minutes! But, in the writing of history there are only degrees of unsuccess. In Chapter 2 John Catt comments on the less than perfect early archival records of the QRA. So it is to his credit that 50 years of archival material has been diligently sifted and edited. In this he was assisted by memories of some named QRA members who are thanked. Wider consultation may have filled some of the gaps. At earlier meetings it was always a pleasure to greet long retired colleagues, such as Archie Lamont at the Carlops glacial drainage system when being demonstrated by Brian Sissons in 1966, or Tony Farringdon at Ballycotton Bay in 1968, or Hallam Movius in 1971 at a London discussion meeting. Similarly, who can forget the field meeting at Canterbury in 1967 when Alec Skempton demonstrated the Sevenoaks by-pass late-glacial slope failures, and John Hutchinson's use of Pomatias elegans for dating the Folkestone Warren landslips? Jan Mangerud's first QRA meeting on the Isle of Man (1971) was notable for his prescient recognition of glaciomarine deposits.

  14. Complex support vector machines for regression and quaternary classification.

    Science.gov (United States)

    Bouboulis, Pantelis; Theodoridis, Sergios; Mavroforakis, Charalampos; Evaggelatou-Dalla, Leoni

    2015-06-01

    The paper presents a new framework for complex support vector regression (SVR) as well as Support Vector Machines (SVM) for quaternary classification. The method exploits the notion of widely linear estimation to model the input-out relation for complex-valued data and considers two cases: 1) the complex data are split into their real and imaginary parts and a typical real kernel is employed to map the complex data to a complexified feature space and 2) a pure complex kernel is used to directly map the data to the induced complex feature space. The recently developed Wirtinger's calculus on complex reproducing kernel Hilbert spaces is employed to compute the Lagrangian and derive the dual optimization problem. As one of our major results, we prove that any complex SVM/SVR task is equivalent with solving two real SVM/SVR tasks exploiting a specific real kernel, which is generated by the chosen complex kernel. In particular, the case of pure complex kernels leads to the generation of new kernels, which have not been considered before. In the classification case, the proposed framework inherently splits the complex space into four parts. This leads naturally to solving the four class-task (quaternary classification), instead of the typical two classes of the real SVM. In turn, this rationale can be used in a multiclass problem as a split-class scenario based on four classes, as opposed to the one-versus-all method; this can lead to significant computational savings. Experiments demonstrate the effectiveness of the proposed framework for regression and classification tasks that involve complex data. PMID:25095266

  15. Petrography and petrology of Quaternary volcanic rocks from Ghezel Ghaleh, northwest Qorveh

    OpenAIRE

    Alireza Bajelan; Morteza Sharifi

    2014-01-01

    Introduction In the east and northeast of Sanandaj in the Qorveh-Bijar-Takab axis, there are series of basaltic composition volcanoes with Quaternary age. The study area is part of the Sanandaj-Sirjan zone and is located between 47°52' and 47°57' E longitudes and 35°26 and '35°30' N latitudes. Due to the location of the volcanic cone on Pliocene clastic sediments and Quaternary travertine, the age of these volcanoes is considered to be Quaternary. The cones mostly consist of low scoria, as...

  16. Extraction of nitro complexes of ruthenium nitrosyl by quaternary ammonium salt

    International Nuclear Information System (INIS)

    103Ru-labeled Na2[Ru(NO2)4OH] complex is prepared and its extractive properties studied in quaternary ammonium-xylene. Distribution coefficients are as high as 103. There are two molecules of quaternary ammonium in the extraction complex. The behaviour and states of ruthenium in the nitric acid solution of irradiated nuclear fuels are investigated. The method of separation and determination of ruthenium in fission products with quaternary ammonium extraction is established. The specific activity of ruthenium in the nuclear fuels is in agreement with the value measured by distilling ruthenium with H2SO4-NaBiO3. (author)

  17. The Quaternary fault in Jiamu area, the Xinjiang Uygur Autonomous Region

    OpenAIRE

    Huafu, Lu; Shengli, Wang; Suppe, John; Hubert, Aurelia; DONG, Jia; Fuli, Yan; Donghau, Yin; JIAN, CHEN

    2002-01-01

    The Quaternary Tailan River fault has been found in the Tianshan foothills area, the Xinjiang Uygur Autonomous Region. It is the recent boundary fault of the Tarim Basin coupling with the West Tianshan Mountains. In the light of measurement data of the slip which cuts the Quaternary deposits of different ages, the Quaternary kine- matic figures of the Tailan River fault are estimated as fol- lows: crustal shortening 3.7 km and shortening rate 1.59 mm/a, uplift of Tianshan Mountains 1.34 km an...

  18. Occurrence of volcanic ash in the Quaternary alluvial deposits, lower Narmada basin, western India

    Indian Academy of Sciences (India)

    Rachna Raj

    2008-02-01

    This communication reports the occurrence of an ash layer intercalated within the late Quaternary alluvial succession of the Madhumati River, a tributary of the lower Narmada River. Petrographic, morphological and chemical details of glass shards and pumice fragments have formed the basis of this study. The ash has been correlated with the Youngest Toba Tuff. The finding of ash layer interbedded in Quaternary alluvial sequences of western Indian continental margin is significant, as ash being datable material, a near precise time-controlled stratigraphy can be interpreted for the Quaternary sediments of western India. The distant volcanic source of this ash requires a fresh re-assessment of ash volume and palaeoclimatic interpretations.

  19. Novel approach for prediction of ultrasonic velocity in quaternary liquid mixtures

    Indian Academy of Sciences (India)

    J D Pandey; A K Singh; Ranjan Dey

    2005-01-01

    A modified Flory theory along with the Auerbach and Altenberg relations has been employed for the computation of ultrasonic velocity of three quaternary liquid mixtures and a comparative study of all the three relations has then been carried out.

  20. Estimated Thickness of Quaternary Sediment in the Wood River Valley aquifer system, South-Central Idaho

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset is the estimated thickness of Quaternary sediment of the Wood River Valley aquifer system. This isopach map was constructed by subtracting the...

  1. Features of the structure Quaternary sediments in typical sections of Middle Dnieper.

    Directory of Open Access Journals (Sweden)

    Manyuk V.

    2013-09-01

    Full Text Available Considered the most important features of the geological feature of the Quaternary deposits, especially in their most typical sections. First we present new evidence about change margin distribution limnoglacial and fluvioglacial deposits.

  2. Phononic First Band Gap of Quaternary Layered Periodic Structure with the Lumped-Mass Method

    Directory of Open Access Journals (Sweden)

    Chen Yuan

    2014-01-01

    Full Text Available Existing band gap analysis is mostly focused on the binary structure, while the researches on the quaternary layered periodic structure are still lacking. In this paper, the unidimensional lumped-mass method in the phonic crystal theory is firstly improved so that the material viscoelasticity can be taken into consideration. Then, the binary layered periodic structure is converted into a quaternary one and band gaps appear at low frequency range. Finally, the effects of density, elastic modulus, damping ratio, and the thickness of single material on the first band gap of the quaternary layered periodic structure are analyzed after the algorithm is promoted. The research findings show that effects of density, elastic modulus, and thickness of materials on the first band gap are considerable but those of damping ratio are not so distinct. This research provides theoretical bases for band gap design of the quaternary layered periodic structure.

  3. OMVPE Growth of Quaternary (Al,Ga,In)N for UV Optoelectronics (title change from A)

    Energy Technology Data Exchange (ETDEWEB)

    HAN,JUNG; FIGIEL,JEFFREY J.; PETERSEN,GARY A.; MYERS JR.,SAMUEL M.; CRAWFORD,MARY H.; BANAS,MICHAEL ANTHONY; HEARNE,SEAN JOSEPH

    2000-01-18

    We report the growth and characterization of quaternary AlGaInN. A combination of photoluminescence (PL), high-resolution x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) characterizations enables us to explore the contours of constant PL peak energy and lattice parameter as functions of the quaternary compositions. The observation of room temperature PL emission at 351nm (with 20% Al and 5% In) renders initial evidence that the quaternary could be used to provide confinement for GaInN (and possibly GaN). AlGaInN/GrdnN MQW heterostructures have been grown; both XRD and PL measurements suggest the possibility of incorporating this quaternary into optoelectronic devices.

  4. Metalorganic Vapor-Phase Epitaxial Growth and Characterization of Quaternary AlGaInN

    Energy Technology Data Exchange (ETDEWEB)

    BANAS, MICHAEL ANTHONY; CRAWFORD, MARY H.; FIGIEL, JEFFREY J.; HAN, JUNG; LEE, STEPHEN R.; MYERS JR., SAMUEL M.; PETERSON, GARY D.

    1999-09-27

    In this letter we report the growth (by MOVPE) and characterization of quaternary AlGaInN. A combination of PL, high-resolution XRD, and RBS characterizations enables us to explore and delineate the contours of equil-emission energy and lattice parameters as functions of the quaternary compositions. The observation of room temperature PL emission as short as 351nm (with 20% Al and 5% In) renders initial evidence that the quaternary could be used to provide confinement for GaInN (and possibly GaN). AlGaInN/GdnN MQW heterostructures have also been grown; both x-ray diffraction and PL measurement suggest the possibility of incorporating this quaternary into optoelectronic devices.

  5. Fluctuations in productivity and denitrification in the southeastern Arabian Sea during the Late Quaternary

    Digital Repository Service at National Institute of Oceanography (India)

    Kessarkar, P.M.; Rao, V.P.; Naqvi, S.W.A.; Chivas, A.R.; Saino, T.

    , R. K. and Rajagopalan, G., A δ 13 C record of late Quaternary climate change from tropical peats in southern India. Nature, 1993, 364, 703–706. 41. Sarkar, A., Ramesh, R., Bhattacharya, S. K. and Price, N. B., Palaeomonsoon...

  6. Antibacterial properties of poly(quaternary ammonium) modified gold and titanium dioxide nanoparticles.

    Science.gov (United States)

    Wan, Weijie; Yeow, John T W

    2012-06-01

    We report excellent antibacterial effect induced by amine-functionalized gold and titanium dioxide nanoparticles without external excitations. The idea originates from the excellent antibacterial property of quaternary ammonium salts. The effects of poly(quaternary ammonium) and polyacrylate sodium functional groups as nanoparticle surfactants are compared to show that poly(quaternary ammonium) functional groups are the main cause of the induced antibacterial effect. 99.999% of E. coli can be destructed in 10 minutes by simply mixing bacteria with nanoparticle dispersions. The effect of nanoparticle concentrations on the antibacterial property is evaluated. Time required to significantly suppress bacteria growth is studied. The result indicates that the excellent antibacterial property can be introduced to any nanomaterials by using poly(quaternary ammonium) functional groups as surfactants. The engineered nanoparticles can find enormous applications such as self-cleaning surfaces, waste water treatment, Lab-on-a-Chip devices and many more. PMID:22905506

  7. Synthesis of Main-Chain Chiral Quaternary Ammonium Polymers for Asymmetric Catalysis Using Quaternization Polymerization

    Directory of Open Access Journals (Sweden)

    Md. Masud Parvez

    2012-06-01

    Full Text Available Main-chain chiral quaternary ammonium polymers were successfully synthesized by the quaternization polymerization of cinchonidine dimer with dihalides. The polymerization occurred smoothly under optimized conditions to give novel type of main-chain chiral quaternary ammonium polymers. The catalytic activity of the polymeric chiral organocatalysts was investigated on the asymmetric benzylation of N-(diphenylmethylideneglycine tert-butyl ester.

  8. Quantification of Quaternary Structure Stability in Aggregation-Prone Proteins under Physiological Conditions: The Transthyretin Case

    OpenAIRE

    Robinson, Lei Z.; Reixach, Natàlia

    2014-01-01

    The quaternary structure stability of proteins is typically studied under conditions that accelerate their aggregation/unfolding processes on convenient laboratory time scales. Such conditions include high temperature or pressure, chaotrope-mediated unfolding, or low or high pH. These approaches have the limitation of being nonphysiological and that the concentration of the protein in solution is changing as the reactions proceed. We describe a methodology to define the quaternary structure s...

  9. Quaternary Alkylammonium Conjugates of Steroids: Synthesis, Molecular Structure, and Biological Studies.

    Science.gov (United States)

    Brycki, Bogumił; Koenig, Hanna; Pospieszny, Tomasz

    2015-01-01

    The methods of synthesis as well as physical, spectroscopic (¹H-NMR, 13C-NMR, and FT-IR, ESI-MS), and biological properties of quaternary and dimeric quaternary alkylammonium conjugates of steroids are presented. The results were contrasted with theoretical calculations (PM5 methods) and potential pharmacological properties (PASS). Alkylammonium sterols exhibit a broad spectrum of antimicrobial activity comparable to squalamine. PMID:26610455

  10. Atmospheric effects on Quaternary polarization encoding for free space communication, laboratory simulation

    OpenAIRE

    Soorat, Ram; Vudayagiri, Ashok

    2015-01-01

    We have simulated atmospheric effects such as fog and smoke in laboratory environment to simulate depolarisation due to atmospheric effects during a free space optical communi- cation. This has been used to study noise in two components of quaternary encoding for polarization shift keying. Individual components of a Quaternary encoding, such as vertical and horizontal as well as 45$^\\circ$ and 135$^\\circ$ , are tested separately and indicates that the depo- larization effects are different fo...

  11. Antagonism by lipophilic quaternary ions of the K+ channel opener, levcromakalim, in vascular smooth muscle.

    OpenAIRE

    McPherson, G. A.; Piekarska, A. E.

    1994-01-01

    1. The aim of this study was to characterize the interaction between the K+ channel opener levcromakalim (LKM) and several quaternary ions, in vascular smooth muscle, in vitro. Segments of isolated, thoracic aorta of the rat were suspended in organ baths filled with Krebs solution at 37 degrees C. Cumulative concentration-response curves to LKM were obtained in the absence and in the presence of increasing concentrations of quaternary ions using a number of agents to pre-constrict the vessel....

  12. Calcium Nodules as a Proxy for Quaternary Paleoclimate Change on China’s Loess Plateau

    OpenAIRE

    He, Wenming; He, Hongming; Zhu, Mingyong

    2015-01-01

    Different proxies have been used to investigate Quaternary paleoclimate change. Here, we used weathering of calcium nodules in paleosols on China’s Loess Plateau as a proxy for Quaternary paleoclimate changes to provide an alternative indicator of these changes. Paleosol and carbonate nodules were collected from Luochuan and Lantian counties in Shaanxi Province, China. We found that this approach allowed quantitative reconstruction of temperature, rainfall, soil mineral composition, and the e...

  13. Quaternary Alkylammonium Conjugates of Steroids: Synthesis, Molecular Structure, and Biological Studies

    Directory of Open Access Journals (Sweden)

    Bogumił Brycki

    2015-11-01

    Full Text Available The methods of synthesis as well as physical, spectroscopic (1H-NMR, 13C-NMR, and FT-IR, ESI-MS, and biological properties of quaternary and dimeric quaternary alkylammonium conjugates of steroids are presented. The results were contrasted with theoretical calculations (PM5 methods and potential pharmacological properties (PASS. Alkylammonium sterols exhibit a broad spectrum of antimicrobial activity comparable to squalamine.

  14. Application of linear free energy relations to protein conformational changes: the quaternary structural change of hemoglobin.

    OpenAIRE

    Eaton, W A; Henry, E. R.; Hofrichter, J

    1991-01-01

    The transition state for the R in equilibrium with T quaternary conformational change of hemoglobin has thermodynamic properties much closer to those of the R conformation than to those of the T conformation. This finding is based on a comparison of activation and equilibrium enthalpy and entropy changes and on the observation of a linear free energy relationship between quaternary rate and equilibrium constants. A previous theoretical study [Janin, J. & Wodak, S. J. (1985) Biopolymers 24, 50...

  15. Progress report. Task 1 - quaternary tectonics, 1 October 1991--30 September 1992

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-09-30

    Progress is reported on a study concerned with the quaternary tectonics of Yucca Mountain, the proposed site for an underground disposal facility for high-level radioactive wastes. Refinement and revision of crater Flat Quaternary stratigraphy continued and consisted of several activities: revision of rock varnish cation leaching curve; sample comparison of RV manganese;,iron microlaminations;and correlation of Crater Flat allostratigraphic units with regional chronologies.

  16. Beyond BLASTing: Tertiary and Quaternary Structure Analysis Helps Identify Major Vault Proteins

    OpenAIRE

    Daly, Toni K.; Sutherland-Smith, Andrew J.; Penny, David

    2012-01-01

    We examine the advantages of going beyond sequence similarity and use both protein three-dimensional (3D) structure prediction and then quaternary structure (docking) of inferred 3D structures to help evaluate whether comparable sequences can fold into homologous structures with sufficient lateral associations for quaternary structure formation. Our test case is the major vault protein (MVP) that oligomerizes in multiple copies to form barrel-like vault particles and is relatively widespread ...

  17. The pragmatic roots of American Quaternary geology and geomorphology

    Science.gov (United States)

    Baker, Victor R.

    1996-07-01

    H.L. Fairchild's words from the 1904 Geological Society of America Bulletin remain appropriate today: "Geologists have been too generous in allowing other people to make their philosophy for them". Geologists have quietly followed a methodological trinity involving (1) inspiration by analogy, (2) impartial and critical assessment of hypotheses, and (3) skepticism of authority (prevailing theoretical constraints or paradigms). These methods are described in classical papers by Quaternary geologists and geomorphologists, mostly written a century ago. In recent years these papers have all been criticized in modern philosophical terms with little appreciation for the late 19th century American philosophical tradition from which they arose. Recent scholarly research, however, has revealed some important aspects of that tradition, giving it a coherence that has largely been underappreciated as 20th century philosophy of science pursued its successive fads of logical positivism, critical rationalism, relativism, and deconstructivism — for all of which "science" is synonymous with "physics". Nearly all this ideology is geologically irrelevant. As philosophy of science in the late 20th century has come to be identical with philosophy of analytical physics, focused on explanations via ideal truths, much of geology has remained true to its classical doctrines of commonsensism, fallibilism, and realism. In contrast to the conceptualism and the reductionism of the analytical sciences, geology has emphasized synthetic thinking: the continuous activity of comparing, connecting, and putting together thoughts and perceptions. The classical methodological studies of geological reasoning all concern the formulation and testing of hypotheses. Analysis does not serve to provide the ultimate answers for intellectual puzzles predefined by limiting assumptions imposed on the real world. Rather, analysis in geology allows the investigator to consider the consequential effects of

  18. Quaternary continetal back-arc evolution from southern Mendoza, Argentina

    Science.gov (United States)

    Espanon, Venera; Chivas, Allan; Dosseto, Anthony; Honda, Masahiko; Phillips, David; Matchan, Erin; Price, David

    2016-04-01

    The Quaternary evolution of the Payenia Basaltic Province (PBP) in southern Mendoza, Argentina has been investigated using a multi-dating approach in combination with pre-exiting geochemical data. This basaltic province covers an area of approximately 40000 km2 and is mainly characterised by backarc volcanism. In the current investigation nine new radiometric ages obtained using surface exposure, 40Ar/39Ar and thermoluminescence dating are presented. Six ages correspond to the late Pleistocene and three to the Holocene. The surface exposure ages obtained using cosmogenic 3He and 21Ne are in good agreement with previous publications and confidently suggest that part of this basaltic province was active at least 4000 years ago (taking a conservative approach). In addition, we combined the available geochronological and geochemical data to reconstruct the Quaternary evolution of this basaltic province. This approach was used to create maps of geospatial distribution of trace-element ratios to determine geochemical changes during the Pleistocene. Employing this method it is evident that two geochemical distinct types of magma were erupting at the same time interval within the PBP. In the north eastern part (Nevado volcanic field) of the PBP an arc-like signature is evident, while in the southern part (Río Colorado volcanic field) of the same basaltic province an Ocean Island Basalt (OIB) signature is evident. The arc-like signature in the north eastern part of the PBP, decreased during the Pleistocene in a north-west direction indicated by a reduction in Ba/La and La/Ta in the Nevado and Llancanelo volcanic field. The Holocene volcanism is restricted to the western side of the Payún Matrú volcanic field and is dominated by OIB-like signatures such as high Ta/Hf and low Ba/La and La/Ta. This contribution presents new geochronology for the PBP and confirms that two different types of volcanism occurred simultaneously during the Pleistocene, while the Holocene

  19. Late Quaternary sea-level changes of the Persian Gulf

    Science.gov (United States)

    Lokier, Stephen W.; Bateman, Mark D.; Larkin, Nigel R.; Rye, Philip; Stewart, John R.

    2015-07-01

    Late Quaternary reflooding of the Persian Gulf climaxed with the mid-Holocene highstand previously variously dated between 6 and 3.4 ka. Examination of the stratigraphic and paleoenvironmental context of a mid-Holocene whale beaching allows us to accurately constrain the timing of the transgressive, highstand and regressive phases of the mid- to late Holocene sea-level highstand in the Persian Gulf. Mid-Holocene transgression of the Gulf surpassed today's sea level by 7100-6890 cal yr BP, attaining a highstand of > 1 m above current sea level shortly after 5290-4570 cal yr BP before falling back to current levels by 1440-1170 cal yr BP. The cetacean beached into an intertidal hardground pond during the transgressive phase (5300-4960 cal yr BP) with continued transgression interring the skeleton in shallow-subtidal sediments. Subsequent relative sea-level fall produced a forced regression with consequent progradation of the coastal system. These new ages refine previously reported timings for the mid- to late Holocene sea-level highstand published for other regions. By so doing, they allow us to constrain the timing of this correlatable global eustatic event more accurately.

  20. Interaction of ochratoxin A with quaternary ammonium beta-cyclodextrin.

    Science.gov (United States)

    Poór, Miklós; Kunsági-Máté, Sándor; Szente, Lajos; Matisz, Gergely; Secenji, Györgyi; Czibulya, Zsuzsanna; Kőszegi, Tamás

    2015-04-01

    Ochratoxin A (OTA) is a widely spread nephrotoxic food contaminant mycotoxin. Unfortunately, attenuation or prevention of the toxic effects of OTA is still an unresolved problem. Molecular inclusion of OTA by cyclodextrins (CDs) results in complexes with low stability. In the human organism, OTA exists mostly in the dianionic state (OTA(2-)). Therefore, our major goal was to develop a chemically modified cyclodextrin which gives a more stable complex with OTA than the previously published derivatives and which shows stronger preference towards OTA(2-). In our fluorescence spectroscopic study we demonstrate that quaternary ammonium beta-cyclodextrin (QABCD) fulfils both of these requirements. The calculated stability constant of the QABCD-OTA(2-) complex was 28,840 M(-1) (about 200-fold higher than that of the β-CD-OTA(2-) complex). We hypothesize, that QABCD may be a suitable tool for the decontamination of different OTA-contaminated drinks; furthermore, for alleviation of the toxic effects of OTA, such complex formation may reduce its absorption from the intestine. PMID:25442535

  1. Antibacterial Activity of Dental Cements Containing Quaternary Ammonium Polyethylenimine Nanoparticles

    International Nuclear Information System (INIS)

    Glass ionomer cements (GICs) are commonly used for cementing full cast crown restorations. Regrettably, although the dental cements fill the gap between the tooth and the crown, bacterial micro leakage may occur, resulting in secondary caries. As micro leakage cannot be completely prevented, GCS possessing antibacterial properties are in demand. In the present study the antibacterial activity of insoluble, cross-linked quaternary ammonium polyethylenimine (Qp) nanoparticles incorporated at 1% w/w in two clinically available GCS were studied. The antibacterial activity was tested against Streptococcus mutans and Lactobacillus casei using the direct contact test (Dct) and the agar diffusion test (Ad). Using the direct contact test, antibacterial activity (P<0.05) was found in both tested GICs with incorporated QPEI nanoparticles, the effect lasting for at least one month. However, the ADT showed no inhibition halo in the test bacteria, indicating that the antimicrobial nanoparticles do not diffuse into the agar. The results show that the incorporation of QPEI nanoparticles in glass ionomer cements has a long-lasting antibacterial effect against Streptococcus mutans and Lactobacillus casei. Changing the antibacterial properties of glass ionomer cements by incorporating QPEI antibacterial nanoparticles may prolong the clinical performance of dental crowns.

  2. Quaternary ammonium sulfanilamide: a membrane-impermeant carbonic anhydrase inhibitor

    International Nuclear Information System (INIS)

    A novel carbonic anhydrase (CA) inhibitor, quaternary ammonium sulfanilamide (QAS), was tested for potency as a CA inhibitor and for its ability to be excluded from permeating biological membranes. Inhibitor titration plots of QAS vs. pure bovine CA II and CA from the gills of the blue crab, Callinectes sapidus, yielded K/sub i/ values of ∼ 15 μM; thus QAS is a relatively weak but effective CA inhibitor. Permeability of the QAS was directly tested by two independent methods. The inhibitor was excluded from human erythrocytes incubated in 5 mM QAS for 24 h as determined using an 18O-labeled mass spectrometer CA assay for intact cells. Also QAS injected into the hemolymph of C. sapidus (1 or 10 mM) did not cross the basal membrane of the gill. The compound was cleared from the hemolymph by 96 h after injection, and at no time during that period could the QAS be detected in homogenates of gill tissue. Total branchial CA activity was only slightly reduced following the QAS injection. These data indicate that QAS is a CA inhibitor to which biological membranes are impermeable and that can be used in vivo and in vitro in the study of membrane-associated CA

  3. How to describe genes: enlightenment from the quaternary number system.

    Science.gov (United States)

    Ma, Bin-Guang

    2007-01-01

    As an open problem, computational gene identification has been widely studied, and many gene finders (software) become available today. However, little attention has been given to the problem of describing the common features of known genes in databanks to transform raw data into human understandable knowledge. In this paper, we draw attention to the task of describing genes and propose a trial implementation by treating DNA sequences as quaternary numbers. Under such a treatment, the common features of genes can be represented by a "position weight function", the core concept for a number system. In principle, the "position weight function" can be any real-valued function. In this paper, by approximating the function using trigonometric functions, some characteristic parameters indicating single nucleotide periodicities were obtained for the bacteria Escherichia coli K12's genome and the eukaryote yeast's genome. As a byproduct of this approach, a single-nucleotide-level measure is derived that complements codon-based indexes in describing the coding quality and expression level of an open reading frame (ORF). The ideas presented here have the potential to become a general methodology for biological sequence analysis. PMID:16945479

  4. The Quaternary fossil avifauna of Southland, South Island, New Zealand

    International Nuclear Information System (INIS)

    All known Late Quaternary fossil avifauna derived, at various times during the last century, from cave, swamp and dune deposits in Southland, South Island, New Zealand, are described. Fifty eight native bird species are recorded from the deposits, notably including the fourth recort of ''Dendroscansor decurvirostris''. The few leiopelmatid and spenodontid bones are also listed. Taphonomic biases limit comparison of faunal compositions across site-types to moas. However, the moa faunas reveal that quite different avifauna lived in each of the dunes, alluvial swamplands and the well-drained low hills, which probably reflects different vegetation communities in each. Southland supported a mosaic of grassland, shrubland and tall, closed-canopy podocarp forest during the Holocene. Radiocarbon dates on bone gelatin are presented that indicate the fauna of Castle Rocks is of Late-Holocene age, the fauna from Hamiltons Swamp at Winton is of mid-Holocene age, and that from Kauana is >37 080 years old. Is is the oldest swamp fauna so far identified in New Zealand. (author). 61 refs., 6 figs., 5 tabs., 2 appendices

  5. Enhanced adsorption of quaternary amine using modified activated carbon.

    Science.gov (United States)

    Prahas, Devarly; Wang, M J; Ismadji, Suryadi; Liu, J C

    2014-01-01

    This study examined different methodologies to modify activated carbon (AC) for the removal of quaternary amine, tetramethylammonium hydroxide (TMAH), from water. Commercial carbon (WAC) was treated by nitric acid oxidation (NA-WAC), silica impregnation (SM-WAC0.5), and oxygen plasma (P10-WAC), and their characteristics and adsorption capacity were compared. The Langmuir model fitted the equilibrium adsorption data well under different pH. The maximum adsorption capacity of WAC was 27.77 mg/g, while those of NA-WAC, SM-WAC 0.5, and P10-WAC were 37.46, 32.83 and 29.03 mg/g, respectively. Nitric acid oxidation was the most effective method for enhancing the adsorption capacity of TMAH. Higher pH was favorable for TMAH adsorption. Desorption study revealed that NA-WAC had no considerable reduction in performance even after five cycles of regeneration by 0.1 N hydrochloric acid. It was proposed that electrostatic interaction was the main mechanism of TMAH adsorption on activated carbon. PMID:24845325

  6. Formation of Late Quaternary paleoshorelines in Crete, Eastern Mediterranean

    Science.gov (United States)

    Mouslopoulou, Vasiliki; Begg, John; Nicol, Andrew; Oncken, Onno; Prior, Christine

    2015-12-01

    Paleoshorelines of Late Quaternary age in western Crete do not exclusively increase in age with rising altitude as is generally observed worldwide. At numerous sites, for example, Late-Holocene paleoshorelines decrease in age with increasing altitude while in other cases paleoshorelines at similar altitude vary in age by tens of thousands of years. We propose that the observed paleoshoreline altitude-age relationships can be accounted for by eustatic sea-level changes and tectonic rock uplift without requiring substantial errors on radiocarbon ages or tectonic subsidence, as has been previously proposed. To test this model we use a dataset consisting of altitude and age data for 71 individual paleoshorelines sampled from 21 sites distributed along the entire Cretan coastline. These data include radiocarbon ages of marine biota (40 new dates) within beachrock resting on paleoshorelines ranging up to 48 kyr BP in age and ≤20 m above present sea-level. We find that paleoshoreline formation reflects Late Holocene tectonic rock uplift in western Crete, preceded by eustatic sea-level rise and by >10 kyr BP rock uplift along the entire island. Our observations contravene existing models as they suggest that some paleoshorelines, and their associated lithified beachrock, survived passage through the wave-zone multiple times and formed throughout the sea-level cycle (i.e., preservation is not restricted to highstand deposits). These results may have application globally in regions where erosion-resistant carbonate beachrock mantles paleoshorelines.

  7. Quaternary Triphenylphosphonium Compounds: A New Class of Environmental Pollutants.

    Science.gov (United States)

    Schlüsener, Michael P; Kunkel, Uwe; Ternes, Thomas A

    2015-12-15

    A nontarget screening using high-resolution mass spectrometry (HRMS) was established to identify industrial emerging contaminants in the Rhine River. With this approach, quaternary triphenylphosphonium compounds (R-Ph3P(+)) were identified as new emerging contaminants in the aquatic environment. The suggested chemical structures were elucidated by MS fragmentation and chemical databank searches and eventually confirmed via authentic standards. R-Ph3P(+) are used worldwide by the chemical industry to synthesize alkenes via the Wittig reaction. In total, five compounds [R = butyl (Bu), R = ethyl (Et), R = methoxymethyl (MeOMe), R = methyl (Me), and R = phenyl (Ph)] were found in German rivers and streams. R-Ph3P(+) were detected only in those rivers and streams that received an appreciable portion of wastewater from the chemical industry. Up to 2.5 μg/L Et-Ph3P(+) was quantified in a small stream from the Hessian Ried, and in the Rhine, up to 0.56 μg/L Me-Ph3P(+) was detected. R-Ph3P(+) were also identified in suspended particulate matter and sediments in the Rhine catchment, with MeOMe-Ph3P(+) concentrations of up to 0.75 mg/kg and up to 0.21 mg/kg, respectively. Because of the lack of ecotoxicological studies, the environmental risks caused by R-Ph3P(+) can be assessed for neither pelagic nor benthic organisms. PMID:26555603

  8. Equiatomic quaternary Heusler alloys: A material perspective for spintronic applications

    Science.gov (United States)

    Bainsla, Lakhan; Suresh, K. G.

    2016-09-01

    Half-metallic ferromagnetic (HMF) materials show high spin polarization and are therefore interesting to researchers due to their possible applications in spintronic devices. In these materials, while one spin sub band has a finite density of states at the Fermi level, the other sub band has a gap. Because of their high Curie temperature (TC) and tunable electronic structure, HMF Heusler alloys have a special importance among the HMF materials. Full Heusler alloys with the stoichiometric composition X2YZ (where X and Y are the transition metals and Z is a sp element) have the cubic L21 structure with four interpenetrating fcc sublattices. When each of these four fcc sublattices is occupied by different atoms (XX'YZ), a quaternary Heusler structure with different structural symmetries (space group F-43m, #216) is obtained. Recently, these equiatomic quaternary Heusler alloys (EQHAs) with 1:1:1:1 stoichiometry have attracted a lot of attention due to their superior magnetic and transport properties. A special class of HMF materials identified recently is known as spin gapless semiconductors (SGS). The difference in this case, compared with HMFs, is that the density of states for one spin band is just zero at the Fermi level, while the other has a gap as in the case of HMFs. Some of the reported SGS materials belong to EQHAs family. This review is dedicated to almost all reported materials belonging to EQHAs family. The electronic structure and hence the physical properties of Heusler alloys strongly depend on the degree of structural order and distribution of the atoms in the crystal lattice. A variety of experimental techniques has been used to probe the structural parameters and degree of order in these alloys. Their magnetic properties have been investigated using the conventional methods, while the spin polarization has been probed by point contact Andreev reflection technique. The experimentally obtained values of saturation magnetization are found to be in

  9. Europe's Neogene and Quaternary lake gastropod diversity - a statistical approach

    Science.gov (United States)

    Neubauer, Thomas A.; Georgopoulou, Elisavet; Harzhauser, Mathias; Mandic, Oleg; Kroh, Andreas

    2014-05-01

    During the Neogene Europe's geodynamic history gave rise to several long-lived lakes with conspicuous endemic radiations. However, such lacustrine systems are rare today as well as in the past compared to the enormous numbers of "normal" lakes. Most extant European lakes are mainly results of the Ice Ages and are due to their (geologically) temporary nature largely confined to the Pleistocene-Holocene. As glacial lakes are also geographically restricted to glacial regions (and their catchment areas) their preservation potential is fairly low. Also deposits of streams, springs, and groundwater, which today are inhabited by species-rich gastropod assemblages, are rarely preserved. Thus, the pre-Quaternary lacustrine record is biased towards long-lived systems, such as the Late Miocene Lake Pannon, the Early to Middle Miocene Dinaride Lake System, the Middle Miocene Lake Steinheim and several others. All these systems have been studied for more than 150 years concerning their mollusk inventories and the taxonomic literature is formidable. However, apart from few general overviews precise studies on the γ-diversities of the post-Oligocene European lake systems and the shifting biodiversity in European freshwater systems through space and time are entirely missing. Even for the modern faunas, literature on large-scale freshwater gastropod diversity in extant lakes is scarce and lacks a statistical approach. Our preliminary data suggest fundamental differences between modern and pre-Pleistocene freshwater biogeography in central Europe. A rather homogenous central European Pleistocene and Holocene lake fauna is contrasted by considerable provincialism during the early Middle Miocene. Aside from the ancient Dessaretes lakes of the Balkan Peninsula, Holocene lake faunas are dominated by planorbids and lymnaeids in species numbers. This composition differs considerably from many Miocene and Pliocene lake faunas, which comprise pyrgulid-, hydrobiid-, viviparid-, melanopsid

  10. Energy saving of side-column DWCs for quaternary separation

    International Nuclear Information System (INIS)

    Side-column DWCs (divided wall columns) are proposed for the energy saving from the conventional three-column distillation system. The proposed columns are energy-efficient and compact to be installed in small construction space. The energy requirement, economics and thermodynamic efficiency of the side-column DWCs are evaluated and compared with the conventional system. Two example processes, the BTX and aliphatic compound mixture processes, are utilized for the evaluation. The heating and cooling duties of the side-rectifier DWC for the BTX process are 8.5% and 9.1% less than the conventional system, respectively. Those of the side-stripper DWC for the aliphatic compound mixture process are 10.2% and 10.8% less, respectively. The economic evaluation indicates that both side-column DWCs require slightly more investment cost than the conventional system, but their utility costs are 6% and 12.9% less than the conventional system for the BTX and aliphatic compound mixture processes, respectively. While the thermodynamic efficiency of the BTX process is 0.4% point higher than the conventional system, the efficiency of the aliphatic compound mixture process is 0.3% point lower. The characteristic of the side-column DWCs is explained to improve the column design, and the operational difficulty is examined to indicate the improvement from the existing DWC. - Highlights: • Side-column DWC processes quaternary mixture. • Single column construction is available. • Energy savings between 8.5% and 10.8% are yielded. • Utility cost savings are 6% and 12.9%. • Commercially proven DWC is utilized

  11. Tetracalcium phosphate composite containing quaternary ammonium dimethacrylate with antibacterial properties

    Science.gov (United States)

    Cheng, Lei; Weir, Michael D.; Limkangwalmongkol, Penwadee; Hack, Gary D.; Xu, Hockin H. K.; Chen, Qianming; Zhou, Xuedong

    2012-01-01

    Tooth caries is a carbohydrate-modified bacterial infectious disease, and recurrent caries is a frequent reason for restoration failure. The objective of this study was to develop a novel antibacterial composite using tetracalcium phosphate (TTCP) fillers and bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide, which is a quaternary ammonium dimethacrylate (QADM). QADM was synthesized using 2-(N,N-dimethylamino)ethyl methacrylate and 2-bromoethyl methacrylate and incorporated into a resin. The resin was filled with 40% TTCP and 30% glass particles. The following QADM mass fractions in the composite were tested: 0%, 6%, 12%, and 18%. Streptococcus mutans biofilms were formed on the composites and the colony-forming units (CFUs), metabolic activity, and lactic acid production were measured. The TTCP-QADM composite had flexural strength and elastic modulus similar to those of two commercial composites (p > 0.1). Increasing the QADM content in TTCP composite greatly decreased the bacteria growth and biofilm matrix production. There were significantly more dead bacteria with increasing QADM content. TTCP composite containing 18% QADM had biofilm CFU, metabolic activity, and acid production about half of those without QADM. Inversely linear relationships were established between QADM mass fraction and S. mutans biofilm CFU, metabolic activity, and acid production, with correlation coefficients R2 ≥ 0.98. In conclusion, TTCP-QADM composites were developed and the effect of QADM mass fraction on the antibacterial properties of the composite was determined for the first time. The novel TTCP-QADM composites possessing a strong antibacterial capability, together with calcium phosphate ion release and good mechanical properties, are promising for dental restorations to reduce biofilm growth and recurrent caries. PMID:22190356

  12. Fusion and Thermal Degradation Behavior of Symmetric Sulfur-Containing Quaternary Ammonium Bromides.

    Science.gov (United States)

    Huynh, Thai L Y; Poiroux, Kaitlyn; O'Brien, Richard A; West, Kevin N; Davis, James H; West, Christy Wheeler

    2016-02-25

    Quaternary ammonium salts are widely used in consumer products and industrial processes, where their instability at elevated temperatures limits their range of applications. In this work, the thermal behavior of a new class of quaternary ammonium salts was investigated using differential scanning calorimetry. These salts contain a sulfur atom in each chain at the fourth position from the central nitrogen and are thus termed thiaquats. The temperatures at which these salts melt and thermally degrade were determined, and enthalpies and entropies of fusion were evaluated. Their melting points increase with chain lengths, in contrast to the behavior of traditional quaternary ammonium salts. Furthermore, they exhibit enthalpies and entropies of fusion significantly lower than corresponding tetraalkyl analogues. These trends provide physical insight into the molecular-level behavior of these salts, suggesting that they do not fully dissociate upon melting. The thiaquats also exhibit thermal stability to markedly higher temperatures than traditional quaternary ammonium bromides, a phenomenon that can be explained in by strong pairing between the quaternary cation and bromide anion, which inhibits possible decomposition mechanisms. This enhanced thermal stability may enable applications of these salts in processes where traditional salts are not viable, such as phase-transfer-catalyzed systems performed at elevated temperatures. PMID:26849572

  13. Mineralogical characteristics of the superlarge Quaternary bauxite deposits in Jingxi and Debao counties, western Guangxi, China

    Science.gov (United States)

    Liu, Xuefei; Wang, Qingfei; Zhang, Qizuan; Feng, Yuewen; Cai, Shuhui

    2012-06-01

    In recent decades, more than 0.5 billion tons of ores scattered in the Quaternary laterite in western Guangxi, China have been explored. The ores were derived from a bauxite horizon in Permian via physical break-up and re-sediment process. Utilizing various test methods, i.e., XRD, DTA, TG/DTG, SEM/EDS and EPMA, the mineralogical characteristics of the Quaternary bauxite ores in Jingxi and Debao counties were investigated. XRD was used together with TG/DTG to obtain relatively accurate ore mineral abundance. Diaspore is the major phase, whereas hematite, kaolinite, anatase, chamosite, gibbsite, goethite, illite and rutile are minor. Diaspore is characterized by a small particle size, low degrees of crystallinity and complex chemical composition. Both gibbsite and goethite have a varied particle size, and goethite crystals contain high Al substitution and Si. It is clarified that diaspore, chamosite and anatase were formed in a mildly reduced and alkaline depositional environment in Permian, while gibbsite, hematite, goethite and part kaolinite were precipitated from Al3+-, Si4+- and Fe3+-enriched solutions within an Quaternary oxidized environment. The ions Al3+, Si4+ and Fe3+ are mostly released from chamosite in its dissolution process. The different physicochemical conditions between the Permian depositional and the Quaternary weathering periods resulted in a complex mineral assemblage in the Quaternary bauxite.

  14. Phases and phase equilibria in the quaternary system Ti-Cu-Al-N at 850 C

    Energy Technology Data Exchange (ETDEWEB)

    Durlu, N. [Vienna Univ. (Austria); Gruber, U. [Vienna Univ. (Austria); Pietzka, M.A. [Vienna Univ. (Austria); Schmidt, H. [Vienna Univ. (Austria); Schuster, J.C. [Vienna Univ. (Austria)

    1997-05-01

    Phase equilibria in the quaternary system Ti-Cu-Al-N are investigated using XRD, metallography and EDX, yielding the observation of 18 four phase spaces of the 850 C isotherm. In the ternary boundary systems Ti-Cu-Al and Ti-Al-N, all previously reported phases are confirmed, but several tielines are newly determined. In the system Ti-N, the new ternary phase Ti{sub 3}CuN dominates most phase fields. Based on thermochemical data of the binary boundary systems and the newly investigated or re-investigated phase equilibria of the ternary boundary systems, a set of Gibbs energies for the solid phases occuring in the quaternary system is derived, which is used in combination with the quaternary experimental data to derive a large section of the isotherm for Ti-Cu-Al-N at 850 C. The quaternary {eta}-phase (Ti, Cu, Al){sub 6}N having the composition Ti{sub 3}Cu{sub 2}Al{sub 1}N{sub 0.8} is found to be the only stable quaternary phase of this system. Several {eta}-phases isotypic to Ti{sub 3}Cu{sub 2}Al{sub 1}N{sub 0.8} are synthesized to explore the crystal chemistry effects of substitutions on different crystallographic sites. (orig.)

  15. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    International Nuclear Information System (INIS)

    The aim of this study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. According to our study, the salient features for the ternary alloy are a negative SRO parameter between Ni–Cr and a positive between Cr–Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni–Cr and Ni–Fe pairs and positive for Cr–Cr and Fe–Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. The predicted SRO has an impact on point-defect energetics, electron–phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys

  16. Quaternary extensional growth folding beneath Reno, Nevada, imaged by urban seismic profiling

    Science.gov (United States)

    Stephenson, William J.; Frary, Roxy N.; Louie, John; Odum, Jackson K.

    2013-01-01

    We characterize shallow subsurface faulting and basin structure along a transect through heavily urbanized Reno, Nevada, with high‐resolution seismic reflection imaging. The 6.8 km of P‐wave data image the subsurface to approximately 800 m depth and delineate two subbasins and basin uplift that are consistent with structure previously inferred from gravity modeling in this region of the northern Walker Lane. We interpret two primary faults that bound the uplift and deform Quaternary deposits. The dip of Quaternary and Tertiary strata in the western subbasin increases with greater depth to the east, suggesting recurrent fault motion across the westernmost of these faults. Deformation in the Quaternary section of the western subbasin is likely evidence of extensional growth folding at the edge of the Truckee River through Reno. This deformation is north of, and on trend with, previously mapped Quaternary fault strands of the Mt. Rose fault zone. In addition to corroborating the existence of previously inferred intrabasin structure, these data provide evidence for an active extensional Quaternary fault at a previously unknown location within the Truckee Meadows basin that furthers our understanding of both the seismotectonic framework and earthquake hazards in this urbanized region.

  17. Atmospheric effects on Quaternary polarization encoding for free space communication, laboratory simulation

    CERN Document Server

    Soorat, Ram

    2015-01-01

    We have simulated atmospheric effects such as fog and smoke in laboratory environment to simulate depolarisation due to atmospheric effects during a free space optical communi- cation. This has been used to study noise in two components of quaternary encoding for polarization shift keying. Individual components of a Quaternary encoding, such as vertical and horizontal as well as 45$^\\circ$ and 135$^\\circ$ , are tested separately and indicates that the depo- larization effects are different for these two situation. However, due to a differential method used to extract information bits, the protocol shows extremely low bit error rates. The information obtained is useful during deployment of a fully functional Quaternary encoded PolSK scheme in free space.

  18. Efficient method of starch functionalization to bis-quaternary structure unit.

    Science.gov (United States)

    Chauhan, Kalpana; Kaur, Jasvinder; Kumari, Ankita; Kumari, Anita; Chauhan, G S

    2015-09-01

    This paper presents the synthesis of bis-quaternary starch by innocuous reagents. For this, starch was functionalized to di-aldehyde structure by periodate oxidation. Aldehyde is reactive and amenable to further derivatization to amine structure. It was functionalized to amine via the modified Leuckart-Wallach reaction. Then, the aminated starch was modified to the quaternary form by the exhaustive methylation. The structural characterization of synthesized compounds was performed using titrimetric analytical estimation, FTIR, (1)H NMR, (13)C NMR, and SEM-EDX. Analytical results showed 58.8% aldehyde content in di-aldehyde starch. The synthesized quaternary derivatives with gemini like structure showed high degree of quaternization 62%. In conclusion, the applied protocol is efficient and revealed high extent of modification with almost good uniformity from the characterization studies. PMID:26187192

  19. Quaternary borocarbides: Relatively high Tc intermetallic superconductors and magnetic superconductors

    Science.gov (United States)

    Mazumdar, Chandan; Nagarajan, R.

    2015-07-01

    Discovery of superconductivity in Y-Ni-B-C (Tc ∼ 13 K) gave rise to the class of quaternary rare earth transition metal borocarbide superconductors. Before the discovery of Fe-based arsenide superconductors, this was the only class of materials containing a magnetic element, viz., Ni, yet exhibiting Tcs > 5 K. Many members of this class have high Tc (>10 K). Tc of ∼23 K in Y-Pd-B-C system equaled the record Tc known then, for intermetallics. Another feature that sets this class apart, is the occurrence of the exotic phenomenon of coexistence of superconductivity and magnetism at temperatures >5 K. Availability of large and electronically 'clean' single crystals and large Ginzburg-Landau (G-L) parameter, κ, have enabled detailed investigation of nonlocal effects of superconductivity. Intermediate value of upper critical field Hc2, has enabled detailed investigation of superconductivity in this class, over the complete H-T plane. This has revealed details of anisotropy of superconductivity (e.g., a fourfold symmetry in the square a-b plane is found) and raised questions on the symmetry of order parameter. After a brief outline of the discovery, this article gives a summary of the materials and highlights of superconducting properties of this class of materials. Interesting results from studies, using various techniques, on YNi2B2C (Tc ∼ 15 K) and LuNi2B2C (Tc ∼ 16 K) are presented, including observation of unusual square vortex lattice and its structural transformation with H and T. With conduction electrons involved in the magnetic order of this class of superconductors, the interplay of superconductivity and magnetism is intimate in these magnetic superconductors. With Tc (∼11 K) > TN (∼6 K) in ErNi2B2C, Tc (∼8 K) = TN (∼8 K) in HoNi2B2C and Tc (∼6 K) < TN (∼11 K) in DyNi2B2C, and with other parameters being favorable as mentioned earlier, this class of magnetic superconductors have become ideal materials to investigate the coexistence

  20. Quaternary borocarbides: Relatively high Tc intermetallic superconductors and magnetic superconductors

    International Nuclear Information System (INIS)

    Discovery of superconductivity in Y–Ni–B–C (Tc ∼ 13 K) gave rise to the class of quaternary rare earth transition metal borocarbide superconductors. Before the discovery of Fe-based arsenide superconductors, this was the only class of materials containing a magnetic element, viz., Ni, yet exhibiting Tcs > 5 K. Many members of this class have high Tc (>10 K). Tc of ∼23 K in Y–Pd–B–C system equaled the record Tc known then, for intermetallics. Another feature that sets this class apart, is the occurrence of the exotic phenomenon of coexistence of superconductivity and magnetism at temperatures >5 K. Availability of large and electronically ‘clean’ single crystals and large Ginzburg-Landau (G–L) parameter, κ, have enabled detailed investigation of nonlocal effects of superconductivity. Intermediate value of upper critical field Hc2, has enabled detailed investigation of superconductivity in this class, over the complete H–T plane. This has revealed details of anisotropy of superconductivity (e.g., a fourfold symmetry in the square a–b plane is found) and raised questions on the symmetry of order parameter. After a brief outline of the discovery, this article gives a summary of the materials and highlights of superconducting properties of this class of materials. Interesting results from studies, using various techniques, on YNi2B2C (Tc ∼ 15 K) and LuNi2B2C (Tc ∼ 16 K) are presented, including observation of unusual square vortex lattice and its structural transformation with H and T. With conduction electrons involved in the magnetic order of this class of superconductors, the interplay of superconductivity and magnetism is intimate in these magnetic superconductors. With Tc (∼11 K) > TN (∼6 K) in ErNi2B2C, Tc (∼8 K) = TN (∼8 K) in HoNi2B2C and Tc (∼6 K) < TN (∼11 K) in DyNi2B2C, and with other parameters being favorable as mentioned earlier, this class of magnetic superconductors have become ideal materials to investigate

  1. Evidence against Late Quaternary activity along the Northern Karakoram Fault

    Science.gov (United States)

    Robinson, A. C.; Owen, L. A.; Hedrick, K.; Blisniuk, K.; Sharp, W. D.; Chen, J.; Schoenbohm, L. M.; Imrecke, D. B.; Yuan, Z.; Li, W.

    2012-12-01

    Although the entire 1000 km long Karakoram fault has long been interpreted to be active, recent work based primarily on interpretation of satellite imagery suggests that the northern end of the fault, where it enters the Pamir mountains, is inactive. We present field observations and geochronologic data from the southern end of the Tashkurgan valley, in the Pamir, on the Karakoram fault where it splits into two identifiable strands; an eastern strand which is the main trace of the Karakoram fault, and a western strand called the Achiehkopai fault. These results support the interpretation that the northern Karakoram fault is currently inactive, and has been for at least 200 ka: 1) Near the village of Dabudaer in the southern Tashkurgan valley the main trace of the Karakoram fault is orthogonally cut by a narrow incised valley with no observed lateral offset across the fault. Within this valley, a strath terrace ~50 m above the active drainage which overlies the main trace of the Karakoram fault which is capped by a carbonate cemented conglomerate. U-series analyses of carbonate cement from a correlative deposit located several km away yields a minimum depositional age of 76±12 ka. This age is coeval with the local Tashkurgan glacial stage we dated using Be-10 surface exposure dating (66±10 ka; Owen et al., 2012, Quaternary Science Reviews) suggesting both the conglomerate and strath terrace formed during this glacial stage. 2) ~25 km south of Dabudar, the main trace of the Karakoram projects beneath Tashkurgan glacial stage moraine and fluvial-glacial deposits which similarly show no evidence of disturbance by strike-slip deformation. Both of the above results demonstrate the main trace of the Karakoram fault has been inactive since at least ~70 ka. 3) Both the Karakoram and Achiehkopai faults are overlain by older Dabudaer glacial stage moraine deposits which are interpreted to be at least as old as the penultimate glacial, but may be >200 ka based on our Be-10

  2. Quaternary oxides CaABB1O7 of zirconolite crystal structure

    International Nuclear Information System (INIS)

    Formation of quaternary oxides CaABB'O7 of the composition at A=Ti, Zr, Hf, Sn, B=Al, Ga, Cr, Fe, In, B'=Sb, Nb, Ta is studied. Crystal zirconolite structure has been found in twelve samples containing gallium, ferrum (3) titanium, zirconium, hafnium, niobium, tantalum and antimony (5). In the cases, when A=Sn, B=Al quaternary oxides of the above composition are not formed. It is shown that zirconolite structure stability depends not only on cation dimensions but also on their electron structure

  3. Towards dating Quaternary sediments using the quartz Violet Stimulated Luminescence (VSL) signal

    DEFF Research Database (Denmark)

    Ankjærgaard, C.; Jain, Mayank; Wallinga, J.

    2013-01-01

    Quartz optically stimulated luminescence (OSL) dating is widely used to determine the time of deposition and burial of Late Quaternary sediments. Application of the method is usually limited to the past 150,000 years due to early saturation of the OSL signal. Here we explore the potential to date...... Quaternary sediments using the violet (402 nm) stimulated luminescence (VSL) signal of quartz.We develop and test a new post-blue VSL single aliquot regenerative dose dating protocol, and demonstrate that the VSL signal originates from a deep trap at about 1.9 eV with a thermal lifetime of 1011 years at 10...

  4. Diatoms from the Quaternary sediments of the Nile Delta, Egypt, and their palaeoecological significance

    Science.gov (United States)

    Zalat, Abdelfattah A.

    1995-02-01

    This study represents the first contribution describing diatom taxa from the Quaternary sediments of the Nile Delta, Egypt. A total of 99 diatom species and varieties belonging to 28 genera were identified. The palaeoecological conditions during the time of deposition (pH salinity, eutrophication and dissolved silica concentration) are discussed. Deposition of the Quaternary Nile Delta sediments occurred in slightly alkaline, fresh water of oligohalobian type, which was of variable trophic status with a high dissolved silica concentration. The variations visible in the ratio of planktic to epiphytic and benthic diatoms generally reflect shallow environments with water-level changes related to climatic fluctuations.

  5. Geomorphological effects of plate movemen during Quaternary in China's tropics

    Institute of Scientific and Technical Information of China (English)

    ZHANGWeiqiang; HUANGZhenguo

    2004-01-01

    The eastern and western fronts of plate movement in Taiwan Island and Tibetan Plateau respectively are the two major sources of tectonic force for the morphogensis during Quaternary in China's tropics. Seven examples of geomorphological effects of plate movement are enumerated to discuss the differentiation of tectonic landforms in space and time during Quaternary. The tectonic movement tends to be more active since middle Pleistocene. Some phenomena such as the arc-shape mountain systems, volcanism and crustal deformation imply that the juncture zone of eastern and western tectonic forces is located at about 110°E.

  6. Quaternary Faults and Stress Regime of Venezuela Fallas y campo de esfuerzos cuaternarios de Venezuela

    OpenAIRE

    F.A. Audemard M.; A. Singer P.; J-P. Soulas

    2006-01-01

    Spatial configuration of Quaternary active tectonic features along the southern Caribbean plate boundary suggests that the region is subject to a compressive strike-slip (transpressional senso lato) regime, characterized by a NNW-SSE maximum horizontal stress (sH=s1) and/or an ENE-WSW minimum (s h=s3 or s2) horizontal stress. Stress inversion applied to fault-plane kinematic indicators measured essentially in Plio-Quaternary sedimentary rocks confirms this tectonic regime. Accordingly, this s...

  7. Large-scale and patternable graphene: direct transformation of amorphous carbon film into graphene/graphite on insulators via Cu mediation engineering and its application to all-carbon based devices

    Science.gov (United States)

    Chen, Yu-Ze; Medina, Henry; Lin, Hung-Chiao; Tsai, Hung-Wei; Su, Teng-Yu; Chueh, Yu-Lun

    2015-01-01

    Chemical vapour deposition of graphene was the preferred way to synthesize graphene for multiple applications. However, several problems related to transfer processes, such as wrinkles, cleanness and scratches, have limited its application at the industrial scale. Intense research was triggered into developing alternative synthesis methods to directly deposit graphene on insulators at low cost with high uniformity and large area. In this work, we demonstrate a new concept to directly achieve growth of graphene on non-metal substrates. By exposing an amorphous carbon (a-C) film in Cu gaseous molecules after annealing at 850 °C, the carbon (a-C) film surprisingly undergoes a noticeable transformation to crystalline graphene. Furthermore, the thickness of graphene could be controlled, depending on the thickness of the pre-deposited a-C film. The transformation mechanism was investigated and explained in detail. This approach enables development of a one-step process to fabricate electrical devices made of all carbon material, highlighting the uniqueness of the novel approach for developing graphene electronic devices. Interestingly, the carbon electrodes made directly on the graphene layer by our approach offer a good ohmic contact compared with the Schottky barriers usually observed on graphene devices using metals as electrodes.Chemical vapour deposition of graphene was the preferred way to synthesize graphene for multiple applications. However, several problems related to transfer processes, such as wrinkles, cleanness and scratches, have limited its application at the industrial scale. Intense research was triggered into developing alternative synthesis methods to directly deposit graphene on insulators at low cost with high uniformity and large area. In this work, we demonstrate a new concept to directly achieve growth of graphene on non-metal substrates. By exposing an amorphous carbon (a-C) film in Cu gaseous molecules after annealing at 850 °C, the carbon (a

  8. Late Quaternary Megafaunal Extinctions in Northern Eurasia: Latest Results

    Science.gov (United States)

    Stuart, Anthony

    2010-05-01

    Anthony J. Stuart1 & Adrian M. Lister2 1 Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK. Email: tony.s@megafauna.org.uk 2 Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK. Email: a.lister@nhm.ac.uk. The global extinction of many spectacular species of megafauna (large terrestrial mammals, together with a few large reptiles and birds) within the last c. 50,000 years (Late Quaternary) has been attributed on the one hand to ‘overkill' by human hunters and on the other to environmental change. However, in spite of more than half a century of active interest and research the issue remains unresolved, largely because there are insufficient dated records of megafaunal species for most parts of the world. Northern Eurasia is an especially fruitful region in which to research megafaunal extinctions as it has a wealth of megafaunal material and crucially most extinctions occurred well within the range of radiocarbon dating. Our approach, in a series of projects over the last decade funded by the UK Natural Environment Research Council (NERC), involves amassing radiocarbon dates made directly on megafaunal material from across the entire region: a) by submitting a substantial number of samples (so far c. 500 dates) for AMS dating at Oxford (ORAU); b) obtaining AMS dates from colleagues working on aDNA projects; and c) carefully screening (‘auditing') dates from the literature. The dates (calibrated using OxCal) are plotted as time-sliced maps and as chronological/geographical charts. In our previous work we targeted a range of extinct species from Northern Eurasia: woolly mammoth, woolly rhinoceros, giant deer, cave bear (in collaboration with Martina Pacher), cave lion, and spotted hyaena (which survives today only in Sub-Saharan Africa). By this means we have established a reliable chronology for these extinctions which we are able to compare with the climatic, vegetational and

  9. Quaternary Volcanic Activities in Shandong Peninsula and Northern Parts of Jiangsu and Anhui Provinces

    Institute of Scientific and Technical Information of China (English)

    郑洪汉; 高维明; 等

    1990-01-01

    Quaternary volcanic rocks often coexist with loess,as observed in the same geologic sections in the Shandong Peninsula and northern parts of Jiangsu and Anhui provinces.The development age of Shandong loess in close to that in the middle reaches of the Yellow River.Loess strata are of synchronous implication in the loess belt of North China.So the ages of volcanic activities can be es-timated approximately from the stratigraphic relations between loess layers and volcanic rocks.The re-sults of dating of the Quaternary volcanic rocks,baked layers and the TL dates of loess samples sug-gest that the Quaternary volcanic activity can be divided into 4 stages in the region studied,with the ages being 1.15-1.03,0.86-0.72,0.55-0.33 and 0.02 Ma B.P.respectively .The occurrence of tephra in the Shandong loess sections is possible due to multiple episodes of volcanism during the Quaternary time.

  10. QuaBingo: A Prediction System for Protein Quaternary Structure Attributes Using Block Composition

    Science.gov (United States)

    Tung, Chi-Hua; Chen, Chi-Wei; Guo, Ren-Chao; Ng, Hui-Fuang

    2016-01-01

    Background. Quaternary structures of proteins are closely relevant to gene regulation, signal transduction, and many other biological functions of proteins. In the current study, a new method based on protein-conserved motif composition in block format for feature extraction is proposed, which is termed block composition. Results. The protein quaternary assembly states prediction system which combines blocks with functional domain composition, called QuaBingo, is constructed by three layers of classifiers that can categorize quaternary structural attributes of monomer, homooligomer, and heterooligomer. The building of the first layer classifier uses support vector machines (SVM) based on blocks and functional domains of proteins, and the second layer SVM was utilized to process the outputs of the first layer. Finally, the result is determined by the Random Forest of the third layer. We compared the effectiveness of the combination of block composition, functional domain composition, and pseudoamino acid composition of the model. In the 11 kinds of functional protein families, QuaBingo is 23% of Matthews Correlation Coefficient (MCC) higher than the existing prediction system. The results also revealed the biological characterization of the top five block compositions. Conclusions. QuaBingo provides better predictive ability for predicting the quaternary structural attributes of proteins.

  11. Synthesis, characterization and thermal stability of different polystyryl quaternary ammonium surfactants and their montmorillonite complexes

    International Nuclear Information System (INIS)

    Three polystyryl quaternary ammonium salts have been synthesized from the reactions of trimethylamine with chloromethyl polystyrenes which were prepared by three different methods: free-radical co-polymerization, chloromethylation of polystyrene and anionic polymerization. Then the polystyryl-modified montmorillonites have been obtained from the ion exchange of sodium ions in the montmorillonites with polystyryl quaternary ammonium salts. The polystyryl quaternary ammonium salts have been characterized using proton nuclear magnetic resonance spectrometer (1H NMR), Fourier-transformed infrared spectrometer (FT-IR), and gel permeation chromatography (GPC). The thermal stability of the quaternary ammonium salts and their corresponding modified montmorillonites have been studied by thermo gravimetric analysis (TGA). TGA data have shown that the polystyryl ammonium salt and its modified montmorillonites obtained from the reactions of chloromethyl polystyrene which was prepared by anionic polymerization are the most stable ones respectively. X-ray diffraction (XRD) and transmission electronic microspectroscopy (TEM) analysis of these polystyryl-modified clays have shown that they are of intercalated structures or partial exfoliation with stacked clay layers

  12. Global late Quaternary megafauna extinctions linked to humans, not climate change

    DEFF Research Database (Denmark)

    Sandom, Christopher James; Faurby, Søren; Sandel, Brody Steven;

    2014-01-01

    The late Quaternary megafauna extinction was a severe global-scale event. Two factors, climate change and modern humans, have received broad support as the primary drivers, but their absolute and relative importance remains controversial. To date, focus has been on the extinction chronology of in...

  13. QuaBingo: A Prediction System for Protein Quaternary Structure Attributes Using Block Composition

    Directory of Open Access Journals (Sweden)

    Chi-Hua Tung

    2016-01-01

    Full Text Available Background. Quaternary structures of proteins are closely relevant to gene regulation, signal transduction, and many other biological functions of proteins. In the current study, a new method based on protein-conserved motif composition in block format for feature extraction is proposed, which is termed block composition. Results. The protein quaternary assembly states prediction system which combines blocks with functional domain composition, called QuaBingo, is constructed by three layers of classifiers that can categorize quaternary structural attributes of monomer, homooligomer, and heterooligomer. The building of the first layer classifier uses support vector machines (SVM based on blocks and functional domains of proteins, and the second layer SVM was utilized to process the outputs of the first layer. Finally, the result is determined by the Random Forest of the third layer. We compared the effectiveness of the combination of block composition, functional domain composition, and pseudoamino acid composition of the model. In the 11 kinds of functional protein families, QuaBingo is 23% of Matthews Correlation Coefficient (MCC higher than the existing prediction system. The results also revealed the biological characterization of the top five block compositions. Conclusions. QuaBingo provides better predictive ability for predicting the quaternary structural attributes of proteins.

  14. Epoxidation of Alkenes with Aqueous Hydrogen Peroxide and Quaternary Ammonium Bicarbonate Catalysts

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Kegnæs, Søren

    2013-01-01

    A range of solid and liquid catalysts containing bicarbonate anions were synthesised and tested for the epoxidation of alkenes with aqueous hydrogen peroxide. The combination of bicarbonate anions and quaternary ammonium cations opens up for new catalytic systems that can help to overcome challen...

  15. Modular, Catalytic Enantioselective Construction of Quaternary Carbon Stereocenters by Sequential Cross-Coupling Reactions.

    Science.gov (United States)

    Potter, Bowman; Edelstein, Emma K; Morken, James P

    2016-07-01

    The catalytic Suzuki-Miyaura cross-coupling with chiral γ,γ-disubstituted allylboronates in the presence of RuPhos ligand occurs with high regioselectivity and enantiospecificity, furnishing nonracemic compounds with quaternary centers. Mechanistic experiments suggest that the reaction occurs by transmetalation with allyl migration, followed by rapid reductive elimination. PMID:27310927

  16. PMN-PT based quaternary piezoceramics with enhanced piezoelectricity and temperature stability

    Science.gov (United States)

    Luo, Nengneng; Zhang, Shujun; Li, Qiang; Yan, Qingfeng; He, Wenhui; Zhang, Yiling; Shrout, Thomas R.

    2014-05-01

    The phase structure, piezoelectric, dielectric, and ferroelectric properties of (0.80 - x)PMN-0.10PFN-0.10PZ-xPT were investigated systematically. The morphotropic phase boundary (MPB) was confirmed to be 0.30 PMN-PT based quaternary MPB compositions promising for actuator applications demanding high temperature stability.

  17. Long alkyl chain bis-quaternary ammonium-based ionic liquids as biologically active xanthene dyes

    International Nuclear Information System (INIS)

    New examples of air- and moisture-stable, hydrophobic and hydrophilic bis-quaternary ammonium derived ionic liquids have been prepared. These ionic liquids have been proposed to act as biological active dyes with characteristic unique physicochemical properties, providing alternatives to some conventional anionic xanthene dyes such as eosine Y, fluorescein and erythrosine. (author)

  18. Cyclopropene derivatives as precursors to enantioenriched cyclopropanols and n-butenals possessing quaternary carbon stereocenters.

    Science.gov (United States)

    Simaan, Marwan; Delaye, Pierre-Olivier; Shi, Min; Marek, Ilan

    2015-10-12

    The diastereoselective carbocupration reaction of cyclopropenylmethyl ethers followed by addition of oxenoid leads to the formation of diastereo- and enantiomerically enriched 2,2,3,3-tetrasubstituted cyclopropanol derivatives. Ring fragmentation of the copper cyclopropanolate leads to acyclic butenal derivatives possessing enantiomerically enriched α-quaternary carbon stereocenters in a single-pot operation. PMID:25689601

  19. Coating of adenovirus type 5 with polymers containing quaternary amines prevents binding to blood components

    Czech Academy of Sciences Publication Activity Database

    Šubr, Vladimír; Kostka, Libor; Selby-Milic, T.; Fisher, K.; Ulbrich, Karel; Seymour, W.; Carlisle, R. C.

    2009-01-01

    Roč. 135, č. 2 (2009), s. 152-158. ISSN 0168-3659 R&D Projects: GA AV ČR KJB400500803 EU Projects: European Commission(XE) 512087 - GIANT Institutional research plan: CEZ:AV0Z40500505 Keywords : quaternary ammonium * HPMA * adenovirus Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.949, year: 2009

  20. Synthesis of hierarchical zeolites using an inexpensive mono-quaternary ammonium surfactant as mesoporogen.

    Science.gov (United States)

    Zhu, Xiaochun; Rohling, Roderigh; Filonenko, Georgy; Mezari, Brahim; Hofmann, Jan P; Asahina, Shunsuke; Hensen, Emiel J M

    2014-12-01

    A simple amphiphilic surfactant containing a mono-quaternary ammonium head group (N-methylpiperidine) is effective in imparting substantial mesoporosity during synthesis of SSZ-13 and ZSM-5 zeolites. Highly mesoporous SSZ-13 prepared in this manner shows greatly improved catalytic performance in the methanol-to-olefins reaction compared to bulk SSZ-13. PMID:25316609

  1. High order quaternary arrangement confers increased structural stability to Brucella Spp. lumazine synthase

    Energy Technology Data Exchange (ETDEWEB)

    Zylberman, V.; Craig, P.O.; Klinke, S.; Cauerhff, A.; Goldbaum, F.A. [Instituto Leloir, Buenos Aires (Argentina); Braden, B.C. [Bowie State Univ., Maryland (United States)

    2004-07-01

    The penultimate step in the pathway of riboflavin biosynthesis is catalyzed by the enzyme lumazine synthase (LS). One of the most distinctive characteristics of this enzyme is the structural quaternary divergence found in different species. The protein exists as pentameric and icosahedral forms, built from practically the same structural monomeric unit. The pentameric structure is formed by five 18 kDa monomers, each extensively contacting neighboring monomers. The icosahedral structure consists of 60 LS monomers arranged as twelve pentamers giving rise to a capsid exhibiting icosahedral 532 symmetry. In all lumazine synthases studied, the topologically equivalent active sites are located at the interfaces between adjacent subunits in the pentameric modules. The Brucella spp. lumazine synthase (BLS) sequence clearly diverges from pentameric and icosahedral enzymes. This unusual divergence prompted to further investigate on its quaternary arrangement. In the present work, we demonstrate by means of solution Light Scattering and X-ray structural analyses that BLS assembles as a very stable dimer of pentamers representing a third category of quaternary assembly for lumazine synthases. We also describe by spectroscopic studies the thermodynamic stability of this oligomeric protein, and postulate a mechanism for dissociation/unfolding of this macromolecular assembly. The higher molecular order of BLS increases its stability 20 deg C compared to pentameric lumazine synthases. The decameric arrangement described in this work highlights the importance of quaternary interactions in the stabilization of proteins. (author)

  2. High order quaternary arrangement confers increased structural stability to Brucella Spp. lumazine synthase

    International Nuclear Information System (INIS)

    The penultimate step in the pathway of riboflavin biosynthesis is catalyzed by the enzyme lumazine synthase (LS). One of the most distinctive characteristics of this enzyme is the structural quaternary divergence found in different species. The protein exists as pentameric and icosahedral forms, built from practically the same structural monomeric unit. The pentameric structure is formed by five 18 kDa monomers, each extensively contacting neighboring monomers. The icosahedral structure consists of 60 LS monomers arranged as twelve pentamers giving rise to a capsid exhibiting icosahedral 532 symmetry. In all lumazine synthases studied, the topologically equivalent active sites are located at the interfaces between adjacent subunits in the pentameric modules. The Brucella spp. lumazine synthase (BLS) sequence clearly diverges from pentameric and icosahedral enzymes. This unusual divergence prompted to further investigate on its quaternary arrangement. In the present work, we demonstrate by means of solution Light Scattering and X-ray structural analyses that BLS assembles as a very stable dimer of pentamers representing a third category of quaternary assembly for lumazine synthases. We also describe by spectroscopic studies the thermodynamic stability of this oligomeric protein, and postulate a mechanism for dissociation/unfolding of this macromolecular assembly. The higher molecular order of BLS increases its stability 20 deg C compared to pentameric lumazine synthases. The decameric arrangement described in this work highlights the importance of quaternary interactions in the stabilization of proteins. (author)

  3. Kinetics of Hydrolysis of Cationic Reactive Disperse Dyes Containing Quaternary Group

    Institute of Scientific and Technical Information of China (English)

    XIE Kong-liang; HOU Ai-qin

    2006-01-01

    The kinetics of hydrolysis of cationic reactive disperse dyes containing quaternary group and chemical shift(13CNMR) of the adjacent carbon atoms with pyridine-acetylamino were discussed. The results show pyridine-acetylamino reactive group had higher reactivity than chloroacetylamino and chemical shift(13CNMR) of the adjacent carbon atoms with pyridine-acetylamino moved 18.77 ppm.

  4. Phytolith analysis in fluvial quaternary sediment (San Salvador and Palmar formation) Uruguay river and Argentina eastern

    International Nuclear Information System (INIS)

    This work is about two microfossils fluvial units deposited by the Uruguay river during the Quaternary. These are San Salvador and Palmar formation (Plio-Pleistocene - Upper Pleistocene).The Palmar formation is a band of 4-15 km along the right bank of the Uruguay river outcropping from the eastern provinces of Corrientes and Entre Rios, to Concepcion del Uruguay

  5. Blockfields in Reinheimen Nationalpark, Norway – Neogene weathering remnants or Quaternary periglacial origin?

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou;

    rates of landscape evolution of the mountain summit. References Goodfellow B W, 2012. A granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins. Quaternary Science Reviews, 57, 121- 135. Strømsøe J R, Paasche Ø, 2011....... Weathering patterns in high-latitude regolith. Journal of Geophysical Research: Earth Surface, 116 (F3)...

  6. Synthesis and Spectroscopic Characterisation of N-Alkyl Quaternary Ammonium Salts Typical Precursors of Cyanines

    Directory of Open Access Journals (Sweden)

    P. Almeida

    2002-03-01

    Full Text Available The synthesis and spectroscopic characterisation of some representative N-alkylsubstituted quaternary ammonium salts derived from benzothiazole, benzoxazole, benzoselenazole, indole and quinoline are described. These heterocyclic salts, bearing an activated methyl group in the 2-position in relation to the nitrogen atom and N-methyl, -pentyl, -hexyl and -decyl chains, are typical precursors of cyanine dyes.

  7. Late Quaternary faulting and historic seismicity in the western Lake Mead area, Nevada, Arizona and California

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, L.W.; O' Connel, D.R. (Bureau of Reclamation, Denver, CO (United States))

    1993-04-01

    As part of a regional seismic hazard study for Reclamation dams on the northern lower Colorado River, the age and distribution of known and suspected late Quaternary faults were investigated and historic seismicity was analyzed for the western Lake Mead area. Late Quaternary faults in the area consist of the Mead Slope, Black Hills, Frenchman Mountain, and California Wash faults. Geologic mapping and scarp profiles indicate that of these late Quaternary faults, the Black Hills fault displays evidence for the youngest (probably mid-Holocene) surface faulting. No information about the ages of older events was obtained for any of the faults; however, the ages of the most recent surface-rupturing events for individual faults suggest recurrence intervals of tens of thousands of years for specific faults and regional recurrence rates of several thousand years for M[sub 3] [>=] 6 1/2 events. Since 1936 when Hoover Dam was completed and the initial filling of Lake Mead began, the Boulder Basin area, the largest and deepest part of Lake Mead, has experienced abundant seismic activity that includes some of the largest historic earthquakes in southern Nevada (at least 21 M 4 events and one M 5). Based on earthquake locations from early networks (1937--1950) and those from temporary networks operating in 1975--1976 and 1988, earthquakes are clearly associated with the northeast-striking Mead Slope and Black Hills faults; one of the few associations of seismicity with late Quaternary faults in the Basin and Range. However, earthquakes also appear to be associated with the Fortification fault, a north-striking fault with no evidence of Quaternary surface faulting. Focal mechanisms for some of the 1975--1976 and 1988 events (all events M [<=] 3) suggest active strike-slip/oblique-slip motion on north-striking faults and normal/oblique-slip motion on northeast-striking structures.

  8. Spatiotemporal analysis of Quaternary normal faults in the Northern Rocky Mountains, USA

    Science.gov (United States)

    Davarpanah, A.; Babaie, H. A.; Reed, P.

    2010-12-01

    The mid-Tertiary Basin-and-Range extensional tectonic event developed most of the normal faults that bound the ranges in the northern Rocky Mountains within Montana, Wyoming, and Idaho. The interaction of the thermally induced stress field of the Yellowstone hot spot with the existing Basin-and-Range fault blocks, during the last 15 my, has produced a new, spatially and temporally variable system of normal faults in these areas. The orientation and spatial distribution of the trace of these hot-spot induced normal faults, relative to earlier Basin-and-Range faults, have significant implications for the effect of the temporally varying and spatially propagating thermal dome on the growth of new hot spot related normal faults and reactivation of existing Basin-and-Range faults. Digitally enhanced LANDSAT 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 4 and 5 Thematic Mapper (TM) bands, with spatial resolution of 30 m, combined with analytical GIS and geological techniques helped in determining and analyzing the lineaments and traces of the Quaternary, thermally-induced normal faults in the study area. Applying the color composite (CC) image enhancement technique, the combination of bands 3, 2 and 1 of the ETM+ and TM images was chosen as the best statistical choice to create a color composite for lineament identification. The spatiotemporal analysis of the Quaternary normal faults produces significant information on the structural style, timing, spatial variation, spatial density, and frequency of the faults. The seismic Quaternary normal faults, in the whole study area, are divided, based on their age, into four specific sets, which from oldest to youngest include: Quaternary (>1.6 Ma), middle and late Quaternary (>750 ka), latest Quaternary (>15 ka), and the last 150 years. A density map for the Quaternary faults reveals that most active faults are near the current Yellowstone National Park area (YNP), where most seismically active faults, in the past 1.6 my

  9. Evidences of late quaternary neotectonic activity and sea-level changes along the western continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Veerayya, M.; Thamban, M.; Wagle, B.G.

    The offshore data on sea-level changes along the western margin of India have been reviewed and evidences of Late Quaternary neotectonic activity and subsidence are documented, based on the diagenetic textures of limestones from deeper submarine...

  10. Environmental magnetic studies on some Quaternary sediments of varied depositional settings in the Indian sub-continent

    Digital Repository Service at National Institute of Oceanography (India)

    Sangode, S.J.; Sinha, R.; Phartiyal, B.; Chauhan, O.S.; Mazari, R.K.; Bagati, T.N.; Suresh, N.; Mishra, S.; Kumar, R.; Bhattacharjee, P.

    The efficacy and limitations of routine environmental magnetic approaches to characterize and compare the Quaternary sediments of varied depositional settings (fluvial, fluvio-lacustrine and marine) from the Indian sub-continent are discussed...

  11. Clay minerals as palaeomonsoon proxies: Evaluation and relevance to the late Quaternary records from SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.

    as palaeoclimatic proxies are evaluated and discussed. Systematic investigations using several sediment cores from the SE Arabian Sea reveal that despite the influence of several complicating factors, variations in clay mineral composition during the late Quaternary...

  12. Ground-water quality in quaternary deposits of the central high plains aquifer, south-central Kansas, 1999

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Water samples from 20 randomly selected domestic water-supply wells completed in the Quaternary deposits of south-central Kansas were collected as part of the High...

  13. Impact of Quaternary climatic changes and interspecific competition on the demographic history of a highly mobile generalist carnivore, the coyote

    OpenAIRE

    Koblmüller, S; Robert K Wayne; Leonard, Jennifer A.

    2012-01-01

    Recurrent cycles of climatic change during the Quaternary period have dramatically affected the population genetic structure of many species. We reconstruct the recent demographic history of the coyote (Canis latrans) through the use of Bayesian techniques to examine the effects of Late Quaternary climatic perturbations on the genetic structure of a highly mobile generalist species. Our analysis reveals a lack of phylogeographic structure throughout the range but past population size changes ...

  14. Formation and modelling assessment perculiarities of the Quaternary aquifer system groundwater resources in the Southeastern part of Lithuania

    OpenAIRE

    Štuopis, Anicetas

    2014-01-01

    The aim of the research was accomplish an assessment of the groundwater resources (budget, distribution and formation) and reveal their formation peculiarities in the Quaternary aquifer system of the southeaster part of Lithuania. Substantiation and formulation of schematization principles of the Quaternary multi-aquifer system for conceptualization of groundwater flow model based on the complex of lithologic, hydrogeochemistry, isotopic and hydraulic data have been developed by this disserta...

  15. SN2-type ring opening of substituted--tosylaziridines with zinc (II) halides: Control of racemization by quaternary ammonium salt

    Indian Academy of Sciences (India)

    Manas K Ghorai; Deo Prakash Tiwari; Amit Kumar; Kalpataru Das

    2011-11-01

    Quaternary ammonium salt mediated highly regioselective ring opening of aziridines with zinc(II) halides to racemic and non-racemic -halo amines in excellent yield and selectivity is described. The reaction proceeds via an SN2-type pathway and the partial racemization of the starting substrate and the product was effectively controlled by using quaternary ammonium salts to afford the enantioenriched products (er up to 95:5).

  16. Airborne gamma-ray spectrometric anomaly characteristics and prospecting model for quaternary salt lake type potash deposit

    International Nuclear Information System (INIS)

    On the basis of the airborne gamma-ray spectrometric data, this paper briefly discusses partial scientific research achievements related to prospecting for potash and the establishment of prospecting model for Quaternary salt lake type potash deposit, and furthermore through the analysis on Bieletan and Mahai Potash deposits, it shows that airborne gamma-ray spectrometry is certainly of evident effect in prospecting for Quaternary salt lake type potash deposit

  17. Enantioselective construction of quaternary N-heterocycles by palladium-catalysed decarboxylative allylic alkylation of lactams

    KAUST Repository

    Behenna, Douglas C.

    2011-12-18

    The enantioselective synthesis of nitrogen-containing heterocycles (N-heterocycles) represents a substantial chemical research effort and resonates across numerous disciplines, including the total synthesis of natural products and medicinal chemistry. In this Article, we describe the highly enantioselective palladium-catalysed decarboxylative allylic alkylation of readily available lactams to form 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related lactams. Given the prevalence of quaternary N-heterocycles in biologically active alkaloids and pharmaceutical agents, we envisage that our method will provide a synthetic entry into the de novo asymmetric synthesis of such structures. As an entry for these investigations we demonstrate how the described catalysis affords enantiopure quaternary lactams that intercept synthetic intermediates previously used in the synthesis of the Aspidosperma alkaloids quebrachamine and rhazinilam, but that were previously only available by chiral auxiliary approaches or as racemic mixtures. © 2012 Macmillan Publishers Limited. All rights reserved.

  18. Loess in China: A Good Archive of Climatic and Environmental Changes during the Quaternary

    Institute of Scientific and Technical Information of China (English)

    Wang Limeng; Lu Huayu

    2005-01-01

    @@ Quaternary scientists in China have significantly improved our knowledge of loess deposition as well as our understanding of paleoclimatic and paleoenvironmental changes over the past 2.5 million years. It is recognized that loess is of aeolian origin with loess forming dust continuously deposited. It is also believed that grain-size, magnetic susceptibility, carbon isotopes and fossil assemblages in loess deposits are good proxy indicators of paleomonsoon climate and paleovegetation changes over the past 2.5 million years. Chinese loess is regarded as one of the best terrestrial archives of climatic and environmental changes during the Quaternary.Further investigation of loess deposits and their records of climatic and environmental change aids understanding of climate change and gives scientific backing for the project of ecological and environmental restoration in northwest China.

  19. Thermoelectric properties of quaternary (Bi,Sb)2(Te,Se)3 compound

    International Nuclear Information System (INIS)

    Highlights: • Sb and Se spin–orbit coupling play a key role in the band structure. • Substituted Bi/Sb and Te/Se have a limited impact on the transport coefficients. • n-Type doping will be preferred for quaternary (Bi,Sb)2(Te,Se)3 compound. -- Abstract: The quaternary (Bi,Sb)2(Te,Se)3 compounds are investigated using first-principles study and Boltzmann transport theory. The energy band structure and density of states are studied in detail. The electronic transport coefficients are then calculated as a function of chemical potential. The figure of merit ZT is obtained assuming a constant relaxation time and an averaged thermal conductivity. Our theoretical result agrees well with previous experimental data

  20. Mineralogy of auriferous deposits of the quaternary deposits in the San Luis Province, Argentina

    International Nuclear Information System (INIS)

    The objective of this work is to study the mineralogy of the sands and clays of the quaternary deposits in the San Luis Mountain, Argentina. A series of algorithms applied to the sand fraction has permitted to determine sedimentary discontinuities. The two micron fraction of the sediments has been studied by a quantification technique based on X-ray diffraction by means of oriented preparations and run with copper tube. These quaternary silts have received fluvial lateral contributions. The high cristalinidad of non expandibles and fireclay clay show the antique of the silts. The polygenic processes have generated a great variety of clay mineral species like a large quantities of illite and in lesser extend kaolinite and smectites. The illite was probably generated by diagenetic changes. The high cristalinidad of non expandibles and fireclay clay show the antique of the silts

  1. EVALUATION OF THE ANTIMICROBIAL EFFECTS OF NEW HETEROCYCLIC BIS-QUATERNARY AMMONIUM COMPOUNDS ON BIOFILMS

    Directory of Open Access Journals (Sweden)

    OANA E. CONSTANTIN

    2016-07-01

    Full Text Available Considering the well-known mechanism of adaptable resistance of microorganisms to chemical compounds through biofilms formation and the widespread use of N-heterocyclic quaternary ammonium salts (QAC as disinfectants, in this study we have evaluate the effect of 8 newly synthesized symmetrical and unsymmetrical diquaternary ammonium salts of 1,2-bis-(4-pyridil-ethane on bacterial biofilms produced by three different bacterial strains. The effect of the exposure to quaternary ammonium salts on biofilm communities was investigated within biofilms obtained in a conventional testing system, on stainless steel and glass surfaces. Differential plate counts were used to characterize the developed communities and the effects of QAC exposure and the results were correlated with epifluorescence microphotographs. The data obtained revealed a significant reduction of bacterial cells in the biofilms tested with 4-7 log CFU for all the QAC.

  2. New insights into the earliest Quaternary environments in the Central North Sea from 3D seismic

    Science.gov (United States)

    Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

    2014-05-01

    In the past the transition between an unconformable surface in the south to a conformable horizon towards the north has made identification and mapping the base-Quaternary in the central North Sea difficult (Sejrup et al 1991; Gatliff et al 1994). However recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) has allowed greater confidence in the correlation to the region 3D seismic datasets and thus has allowed the base-Quaternary to be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The revised base-Quaternary surface reaches a depth of 1248 ms TWT with an elongate basin shape which is significantly deeper than the traditionally mapped surface. Using RMS amplitudes and other seismic attributes the revised base-Quaternary has been investigated along the horizon and in time slice to interpret the environments of the earliest Quaternary prior to the onset of glaciation. Combined with analysis of aligned elongate furrows over 10 km long, 100 m wide and 100 m deep suggest a deep marine environment in an almost enclosed basin with persistent strong NW-SE bottom currents in the deepest parts. Pockmarks were formed by the escape of shallow gas on the sides of a small delta in the eastern part of the basin. The progradation of large deltas from both the north and south into the basin make up the majority of the deposition of sediment into the basin. Key Words: base-Quaternary; seismic interpretation; paleoenvironments References: Gatliff, R.W, Richards, P.C, Smith, K, Graham, C.C, McCormac, M, Smith, N.J.P, Long, D, Cameron, T.D.J, Evans, D, Stevenson, A.G, Bulat, J, Ritchie, J.D, (1994) 'United Kingdom offshore regional

  3. A Quaternary-Stage User Interest Model Based on User Browsing Behavior and Web Page Classification

    Institute of Scientific and Technical Information of China (English)

    Zongli Jiang; Hang Su

    2012-01-01

    The key to personalized search engine lies in user model. Traditional personalized model results in that the search results of secondary search are partial to the long-term interests, besides, forgetting to the long-term interests disenables effective recollection of user interests. This paper presents a quaternary-stage user interest model based on user browsing behavior and web page classification, which consults the principles of cache and recycle bin in operating system, by setting up an illuminating text-stage and a recycle bin interest-stage in front and rear of the traditional interest model respectively to constitute the quaternary-stage user interest model. The model can better reflect the user interests, by using an adaptive natural weight and its calculation method, and by efficiently integrating user browsing behavior and web document content.

  4. A new quaternary phase observed in a laser treated Zn–Al–Mg–Si coating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z., E-mail: zchen@uowmail.edu.au [School of Mechanical, Materials and Mechatronic Engineering, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW 2522 (Australia); Peng, C.-T. [School of Mechanical, Materials and Mechatronic Engineering, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW 2522 (Australia); Liu, Q.; Smith, R.; Nolan, D. [Bluescope Steel Research, Bluescope Steel Limited, Locked Bag 8825, Wollongong DC, NSW 2500 (Australia)

    2014-03-15

    Highlights: • A new quaternary phase was discovered in laser treated Zn–55Al–2Mg–1Si coating. • The crystal structure of the new phase was determined by TEM. • The new phase was not a metastable phase induced by the rapid cooling of the laser treatment. • Laser treatment led to not only a much finer microstructure but also changes of phases in the interdendritic areas of the coating. -- Abstract: The microstructure of laser resurfaced Zn–55Al–2Mg–1.5Si coating produced on a hot-dip simulator was characterised by transmission electron microscopy. A new quaternary phase was observed and its crystal structure was determined by electron diffraction.

  5. Preparation and antibacterial properties of gelatin grafted with an epoxy silicone quaternary ammonium salt.

    Science.gov (United States)

    Li, Junying; Sha, Zuoliang; Zhang, Wenyu; Tao, Furong; Yang, Pengfei

    2016-07-01

    Gelatin (GE) was modified with epoxy silicone quaternary ammonium salt (EPSiQA) under alkaline conditions (pH 10-11). Silyl and quaternary ammonium groups were linked to gelatin skeleton simultaneously. It was illustrated by XRD and DSC that the short-range order of GE is destroyed and the glass transition temperature (Tg) of GE drops 10 °C after modification. The measured contact angles and surface free energy calculated by Owens-Wendt equation showed that the surface energy of modified gelatin EPSiQA-GE is mainly contributed by the dispersive component of non-polarity silicone groups, the hydrophobility of EPSiQA-GE increases with the increase of grafted silicone units in gelatin. The results of minimum inhibitory concentration indicated that EPSiQA-GE has bactericidal property against Gram-positive bacteria, Gram-negative bacteria and has no antibacterial effect on mold. PMID:27093873

  6. Paleomagnetic dating of tectonically influenced Plio-Quaternary fan-system deposits from the Apennines (Italy

    Directory of Open Access Journals (Sweden)

    Michele Saroli

    2015-03-01

    Full Text Available The Roveto Valley is a narrow, elongated, NW-trending depression filled with continental Plio-Quaternary deposits that outcrop at different topographic elevations. A morpho-lithostratigraphic succession of the continental deposits has been defined in order to reconstruct the geological Quaternary evolution of the area. These deposits do not contain materials suitable for biostratigraphic dating; therefore, in order to determine their chronology, three different units were sampled for magnetostratigraphic investigations. Paleomagnetic results demonstrated that standard demagnetization techniques are effective in removing secondary remanence components and in isolating the characteristic remanent magnetization, allowing us to determine, for each cycle, whether it was deposited before or after the Brunhes-Matuyama geomagnetic reversal at 781 ka. Preliminary rock magnetic analyses indicated that magnetite is the main magnetic carrier and that hematite, which gives the pink colour to the matrix, is in the superparamagnetic grain-size range and thus does not retain any paleomagnetic remanence.

  7. Synthesis and surface-active property of bis-quaternary ammonium-sodium sulfate Gemini surfactant

    Institute of Scientific and Technical Information of China (English)

    Zhao Qiuling; Gao Zhinong

    2006-01-01

    N,N-dimethyldodecylamine,hydrochloride and epichlorohydrin (molar ration is 2:1:1) were used to synthesize bis-quaternary ammonium Gemini surfactant with a hydroxyl in its spacer group by the one-pot method.This hydroxyl was sulfonated by chlorosulfonic acid and then neutralized to bis-quaternary ammonium-sodium sulfate zwitterionic Gemini surfactant.The yield of the final product was 78%,and the melting point was 231-233℃.Its structure was characterized by IR,1H-NMR,MS,and elemental analyses.The critical micelle concentration (cmc)and surface tension of the novel zwitterionic Gemini surfactant in aqueous solution at 15℃ are 7.2×10-5 mol/L and 34.5 mN/m,respectively.

  8. Visualization of Stage Calculations in Quaternary Reactive Distillation with Multiple Reactions

    International Nuclear Information System (INIS)

    When multiple reactions of quaternary mixtures take place in a reactive distillation column, the behavior of composition trajectory is analyzed by a visual-aided method. By adding additional vectors of multiple reactions and visualizing them in composition space, the composition of each component and extent of each reaction on an arbitrary stage can be easily estimated in terms of the composition trajectory and reaction cascade difference points. Moreover, for a given operating conditions, the number of total stages and position of optimum reaction zone can be determined by the visual-aided method. In this study, ethylene glycol synthesis with a side reaction is taken as an example and analyzed by the proposed graphical method. Through this method, the quaternary reactive distillation with multiple reactions can be analyzed without numerous experiments and simulations

  9. The Quaternary faunas and climatic fluctuation in the tropical zone of China

    Institute of Scientific and Technical Information of China (English)

    HUANGZhenguo; ZHANGWeiqiang

    2003-01-01

    About 70 examples of Quaternary fauna in China's tropics are enumerated in this paper. Of which about 40% of the examples can be found even in cooling stages, showing the smaller amplitude of climatic fluctuation during Quaternary. According to the temporal and spatial distribution of tropical faunas, the following characters of climate variation can be evidenced: two main cycles in Early Pleistocene, three main cycles in Middle Pleistocene, two main cycles in Late Pleistocene and Holocene Megathermal. The drop in temperature during the Latest Glacial Period and Neoglaciation has not endangered the existence of tropical faunas. With influence of cooling fluctuation during historical period, some faunas have removed southwards progressively, but disappearance of these animals in China's tropics was mainly the result of artificial factors.

  10. PREPARATION AND PHOTOSENSITIVITY OF WATER SOLUBLE PHENOLIC RESINS CONTAINING ACRYLOYL AND QUATERNARY AMMONIUM CHLORIDE GROUPS

    Institute of Scientific and Technical Information of China (English)

    Xiao-ming Tan; Hong-quan Xie; Nai-yu Huang

    2002-01-01

    New water soluble and photocrosslinkable prepolymers containing acrylate and quaternary ammonium salt groups were synthesized from epoxy phenolic resin via ring-opening reaction with acrylic acid and with aqueous solution of triethylamine hydrochloride successively. The second reaction needs no phase transfer catalyst to accelerate, since the product formed can act as a phase transfer catalyst. The prepolymer obtained contains both photocrosslinkable acrylate groups and hydrophilic quaternary ammonium salt groups. Optimum conditions for these reactions were studied. The photosensitivity of the prepolymer was also investigated. The effects of different photoinitiators, different crosslinkable diluent monomers and amine accelerator on the photosensitivity of the prepolymer were compared. The photoinitiator of hydrogen abstraction type is still effective without using amine or alcohol as accelerator, because the prepolymer contains α H beside the OH groups formed in the ring-opening reactions.

  11. Influence of quaternary sea-level variations on a land bird endemic to Pacific atolls

    OpenAIRE

    Cibois, Alice; Thibault, Jean-Claude; Pasquet, Eric

    2010-01-01

    Little is known about the effect of quaternary climate variations on organisms that inhabited carbonate islands of the Pacific Ocean, although it has been suggested that one or several uplifted islands provided shelter for terrestrial birds when sea-level reached its highest. To test this hypothesis, we investigated the history of colonization of the Tuamotu reed-warbler (Acrocephalus atyphus) in southeastern Polynesia, and found high genetic structure between the populations of three elevate...

  12. Large carnivore population turnover and ecological change during the Late Quaternary

    OpenAIRE

    Ersmark, Erik

    2016-01-01

    The cave lion (Panthera spelaea), the grey wolf (Canis lupus) and the brown bear (Ursus arctos) all shared an intercontinental distribution across the northern hemisphere during most of the Late Quaternary, and experienced repeated events of climate change. The cave lion went extinct at the end of the Pleistocene and although the wolf and the bear have survived until present day, recent human persecution has caused demographic bottlenecks and local extinctions. In this thesis, mitochondrial a...

  13. New insights on Arctic Quaternary climate variability from palaeo-records and numerical modelling

    OpenAIRE

    Jakobsson, Martin; Long, A; Ingólfsson, Ó.; Kjaer, K. H.; Spielhagen, R. F.

    2010-01-01

    Terrestrial and marine geological archives in the Arctic contain information on environmental change through Quaternary interglacial–glacial cycles. The Arctic Palaeoclimate and its Extremes (APEX) scientific network aims to better understand the magnitude and frequency of past Arctic climate variability, with focus on the “extreme” versus the “normal” conditions of the climate system. One important motivation for studying the amplitude of past natural environmental changes in the Arctic is t...

  14. A novel antibacterial orthodontic cement containing a quaternary ammonium monomer dimethylaminododecyl methacrylate

    OpenAIRE

    Melo, Mary A. S.; Wu, Junling; Weir, Michael D; Xu, Hockin H. K.

    2014-01-01

    Demineralized lesions in tooth enamel around orthodontic brackets are caused by acids from cariogenic biofilm. This study aimed to develop a novel antibacterial orthodontic cement by incorporating a quaternary ammonium monomer dimethylaminododecyl methacrylate (DMADDM) into a commercial orthodontic cement, and to investigate the effects on microcosm biofilm response and enamel bond strength. DMADDM, a recently-synthetized antibacterial monomer, was incorporated into orthodontic cement at 0%, ...

  15. Geochronology of quaternary volcanoes eruptions in Krestovyi pass region (Kazbek neovolcanic area, Greater Caucasus)

    International Nuclear Information System (INIS)

    For studying the latest volcanism in the area of the Greater Caucasus the K-Ar dating of Quaternary lavas in the vicinity of Krestovyi pass region was conducted. The obtained age estimates for all the studied bodies are distinctly subdivided into three groups, i.e. 205-170, 130-70 and less than 30 thousand years, which actually coincide with the time ranges previously identified for basic volcanism phases in this area

  16. Quaternary paleotemperatures and the duration of the high-temperature intervals.

    Science.gov (United States)

    Emiliani, C

    1972-10-27

    Oxygen isotopic analysis of Caribbean cores P6304-4 and P6304-7, and the close correlation of these cores with other Caribbean and Atlantic cores previously analyzed, make possible the reconstruction of a paleotemperature curve of considerable detail. This curve demonstrates again the unusualness of the present interval of high temperature within the framework of Quaternary climatic evolution, and the need for a close study of man's impact on climate. PMID:17815362

  17. Unique Inner Pore Properties of BK Channels Revealed by Quaternary Ammonium Block

    OpenAIRE

    Li, Weiyan; Aldrich, Richard W.

    2004-01-01

    Potassium channels have a very wide distribution of single-channel conductance, with BK type Ca2+-activated K+ channels having by far the largest. Even though crystallographic views of K+ channel pores have become available, the structural basis underlying BK channels' large conductance has not been completely understood. In this study we use intracellularly applied quaternary ammonium compounds to probe the pore of BK channels. We show that molecules as large as decyltriethylammonium (C10) a...

  18. Quaternary epitopes of α345(IV) collagen initiate Alport post-transplant anti-GBM nephritis.

    Science.gov (United States)

    Olaru, Florina; Luo, Wentian; Wang, Xu-Ping; Ge, Linna; Hertz, Jens Michael; Kashtan, Clifford E; Sado, Yoshikazu; Segal, Yoav; Hudson, Billy G; Borza, Dorin-Bogdan

    2013-05-01

    Alport post-transplant nephritis (APTN) is an aggressive form of anti-glomerular basement membrane disease that targets the allograft in transplanted patients with X-linked Alport syndrome. Alloantibodies develop against the NC1 domain of α5(IV) collagen, which occurs in normal kidneys, including renal allografts, forming distinct α345(IV) and α1256(IV) networks. Here, we studied the roles of these networks as antigens inciting alloimmunity and as targets of nephritogenic alloantibodies in APTN. We found that patients with APTN, but not those without nephritis, produce two kinds of alloantibodies against allogeneic collagen IV. Some alloantibodies targeted alloepitopes within α5NC1 monomers, shared by α345NC1 and α1256NC1 hexamers. Other alloantibodies specifically targeted alloepitopes that depended on the quaternary structure of α345NC1 hexamers. In Col4a5-null mice, immunization with native forms of allogeneic collagen IV exclusively elicited antibodies to quaternary α345NC1 alloepitopes, whereas alloimmunogens lacking native quaternary structure elicited antibodies to shared α5NC1 alloepitopes. These results imply that quaternary epitopes within α345NC1 hexamers may initiate alloimmune responses after transplant in X-linked Alport patients. Thus, α345NC1 hexamers are the culprit alloantigen and primary target of all alloantibodies mediating APTN, whereas α1256NC1 hexamers become secondary targets of anti-α5NC1 alloantibodies. Reliable detection of alloantibodies by immunoassays using α345NC1 hexamers may improve outcomes by facilitating early, accurate diagnosis. PMID:23620401

  19. Late Quaternary stratigraphic development in the lower Luni, Mahi and Sabarmati river basins, western India

    Indian Academy of Sciences (India)

    M Jain; S K Tandon; S C Bhatt

    2004-09-01

    This study reviews the Quaternary alluvial stratigraphy in three semi-arid river basins of western India i.e., lower Luni (Rajasthan), and Mahi and Sabarmati (Gujarat alluvial plains). On the basis of OSL chronologies, it is shown that the existing intra-valley lithostratigraphic correlations require a revision. The sand, gravel and mud facies are present during various times in the three basins, however, the fluvial response to climate change, and the resulting facies associations, was different in the Thar desert as compared to that at the desert margin; this makes purely lithostratigraphic correlations unviable. It is further shown that the rivers in the Thar desert were more sensitive to climate change and had small response times and geomorphic thresholds as compared to the desert-margin rivers. This is illustrated during the early OIS 1, when the Luni river in the Thar desert was dynamic and showed frequent variations in fluvial styles such as gravel bedload braided streams, sand-bed ephemeral streams and meandering streams, all followed by incision during the early Holocene. The coeval deposits in Sabarmati, however, only show a meandering, floodplain-dominated river. Late Quaternary alluvial deposits in these basins unconformably overlie some older deposits that lack any absolute chronology. Based on the facies types and their associations, and the composition and architecture of the multistoried gravel sheets in the studied sections, it is suggested that older deposits are of pre-Quaternary age. This hypothesis implies the presence of a large hiatus incorporating much of the Quaternary period in the exposed sections.

  20. Organic and inorganic geochemical aspects of Mediterranean Late Quaternary sapropels and Messinian evaporitic deposits

    OpenAIRE

    Haven, H.L. ten

    1986-01-01

    This thesis describes the results of organic and inorganic geochemical investigations obtained for samples collected from the eastern Mediterranean sea floor and from Italy. The samples vary in age from the Late Miocene up to the Holocene. The environmental conditions prevailing during deposition of the samples differ greatly. Sediment samples deposited under both marine anoxic and oxic conditions were studied as well as samples from hypersaline depositional environments. Late Quaternary east...

  1. Quaternary sector and extended sectoral structure of the economy in the selected European countries

    OpenAIRE

    Kamila Turečková; Stanislav Martinát

    2015-01-01

    This article deals with definition and establishing of extended sectoral structure of the economy in selected EU countries in years 2003 - 2012. Extended sectoral structure is based on traditional sectoral structure enhanced by fourth, quaternary sector which includes all economic activities touching all areas of intellectual activities and operations. Extended sectoral structure reflects changes and impetuses in the economy and society such as formation of knowledge economy, rising importanc...

  2. Geology and mineralogy of the radioactive Quaternary sediments of the North Fayium depression, Western Desert, Egypt

    OpenAIRE

    Fahmy Raslan, Mohamed; Sayed Haroun, Yehia

    2010-01-01

    Quaternary sediments of the North Fayium depression, are mainly represented by residual soil and calcrete, and have been found to be anomalously radioactive. These sediments are deposited on the irregular surface of the carbonaceous shale of the middle member of the Oligocene Qatrani Formation in the northern part of the Fayium depression. A mineralogical investigation involving a preliminary microscopic examination and detailed Environmental Scanning Electron Microscope (ESEM) has revealed t...

  3. Global late Quaternary megafauna extinctions linked to humans, not climate change

    OpenAIRE

    Sandom, C.; Faurby, S; Sandel, B.; Svenning, J.-C.

    2014-01-01

    The late Quaternary megafauna extinction was a severe global-scale event. Two factors, climate change and modern humans, have received broad support as the primary drivers, but their absolute and relative importance remains controversial. To date, focus has been on the extinction chronology of individual or small groups of species, specific geographical regions or macroscale studies at very coarse geographical and taxonomic resolution, limiting the possibility of adequately testing the propos...

  4. Late Quaternary glaciation of the Upper Soca River Region (Southern Julian Alps, NW Slovenia)

    Science.gov (United States)

    Bavec, Milos; Tulaczyk, Slawek M.; Mahan, Shannon; Stock, Gregory M.

    2004-01-01

    Extent of Late Quaternary glaciers in the Upper Soc??a River Region (Southern Julian Alps, SE Europe) has been analyzed using a combination of geological mapping, glaciological modeling, and sediment dating (radiocarbon, U/Th series and Infrared Stimulated Luminescence-IRSL). Field investigations focused mainly on relatively well preserved Quaternary sequences in the Bovec Basin, an intramontane basin located SW of the Mediterranean/Black Sea divide and surrounded by mountain peaks reaching from approximately 2100 up to 2587 m a.s.l. Within the Basin we recognized two Late Quaternary sedimentary assemblages, which consist of the same facies association of diamictons, laminated lacustrine deposits and sorted fluvial sediments. Radiocarbon dating of the upper part of the lake sediments sequence (between 12790??85 and 5885??60 14C years b.p.) indicates that the younger sedimentary assemblage was deposited during the last glacial maximum and through early Holocene (Marine Isotope Stage 21, MIS 2-1). Sediment ages obtained for the older assemblage with U/Th and IRSL techniques (between 154.74??22.88 and 129.93??7.90 ka b.p. for selected samples) have large errors but both methods yield results consistent with deposition during the penultimate glacial-interglacial transition (MIS 6-5). Based on analyses of field data combined with glaciological modeling, we argue that both sediment complexes formed due to high sediment productivity spurred by paraglacial conditions with glaciers present in the uplands around the Bovec Basin but not extending down to the basin floor. Our study shows that the extent and intensity of direct glacial sedimentation by Late Quaternary glaciers in the region was previously significantly overestimated. ?? 2004 Elsevier B.V. All rights reserved.

  5. Agulhas leakage as a key process in the modes of Quaternary climate changes

    OpenAIRE

    Caley, T.; Giraudeau, J.; Malaize, B.; L. Rossignol; Pierre, C

    2012-01-01

    Heat and salt transfer from the Indian Ocean to the Atlantic Ocean (Agulhas leakage) has an important effect on the global thermohaline circulation and climate. The lack of long transfer record prevents elucidation of its role on climate changes throughout the Quaternary. Here, we present a 1,350-ka accumulation rate record of the planktic foraminiferal species Globorotalia menardii. We demonstrate that, according to previous assumptions, the presence and reseeding of this fauna in the subtro...

  6. The quaternary geological history of the Santa Catarina Southeastern Region (Brazil)

    OpenAIRE

    FRANCISCO CARUSO JR.; KENITIRO SUGUIO; TOSHIO NAKAMURA

    2000-01-01

    This paper supply subsidies for Quaternary geological reconstruction of the southeastern State of Santa Catarina coast in Brazil, being based on detailed geological mapping supported by a series of drilling data, which allowed to establish a stratigraphical hierarchy of the sedimentary deposits. Among the mapped geological units stand out the extensive Pleistocene shallow marine sandy sediments, which are commonly referred as a barrier island - lagoonal depositional system. A drilling campaig...

  7. Synthesis and Characterization of Novel Ternary and Quaternary Alkali Metal Thiophosphates

    KAUST Repository

    Alahmary, Fatimah S.

    2014-05-01

    The ongoing development of nonlinear optical (NLO) crystals such as coherent mid-IR sources focuses on various classes of materials such as ternary and quaternary metal chalcophosphates. In case of thiophosphates, the connection between PS4-tetrahedral building blocks and metals gives rise to a broad structural variety where approximately one third of all known ternary (A/P/S) and quaternary (A/M/P/S) (A = alkali metal, M = metal) structures are acentric and potential nonlinear optical materials. The molten alkali metal polychalcophosphate fluxes are a well-established method for the synthesis of new ternary and quaternary thiophosphate and selenophosphate compounds. It has been a wide field of study and investigation through the last two decades. Here, the flux method is used for the synthesis of new quaternary phases containing Rb, Ag, P and S. Four new alkali metal thiophosphates, Rb4P2S10, RbAg5(PS4), Rb2AgPS4 and Rb3Ag9(PS4)4, have been synthesized successfully from high purity elements and binary starting materials. The new compounds were characterized by single crystal and powder X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-VIS), Raman spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). These compounds show interesting structural variety and physical properties. The crystal structures feature 3D anionic framework built up of PS4 tetrahedral units and charge balanced by Ag and alkali metal cations. All prepared compounds are semiconductors with band gap between 2.3 eV to 2.6 eV and most of them are thermally stable up to 600ºC.

  8. Controls on plio-quaternary foreland sedimentation in the region of the Maltese Islands

    OpenAIRE

    Gatt, Peter A.

    2007-01-01

    Plio-Quaternary sediments on the southern foreland of the orogen produced by African-Eurasian plate convergence vary in thick-ness from > 1km in foreland basin and rift graben depocentres to metre-thick deposits over platform environment where depositional hiatuses merge along widespread subaerial surfaces around the Maltese Islands. The syntectonic sedimentation is the result of three episodes: (i) The development of the Pantelleria Rift south of the Maltese Islands by passive rifting, which...

  9. Thermoelectric performance of tellurium-reduced quaternary p-type lead–chalcogenide composites

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: A long-standing technological challenge to the widespread application of thermoelectric generators is obtaining high-performance thermoelectric materials from abundant elements. Intensive study on PbTe alloys has resulted in a high figure of merit for the single-phase ternary PbTe–PbSe system through band structure engineering, and the low thermal conductivity achieved due to nanostructuring leads to high thermoelectric performance for ternary PbTe–PbS compounds. Recently, the single-phase p-type quaternary PbTe–PbSe–PbS alloys have been shown to provide thermoelectric performance superior to the binary and ternary lead chalcogenides. This occurs via tuning of the band structure and from an extraordinary low thermal conductivity resulting from high-contrast atomic mass solute atoms. Here, we present the thermoelectric efficiency of nanostructured p-type quaternary PbTe–PbSe–PbS composites and compare the results with corresponding single-phase quaternary lead chalcogenide alloys. We demonstrate that the very low lattice thermal conductivity achieved is attributed to phonon scattering at high-contrast atomic mass solute atoms rather than from the contribution of secondary phases. This results in a thermoelectric efficiency of ∼1.4 over a wide temperature range (650–850 K) in a p-type quaternary (PbTe)0.65(PbSe)0.1(PbS)0.25 composite that is lower than that of single-phase (PbTe)0.85(PbSe)0.1(PbS)0.05 alloy without secondary phases

  10. Synthetic Studies on Perphoramidine and the Communesins: Construction of the Vicinal Quaternary Stereocenters

    OpenAIRE

    Seo, Jae Hong; Artman, Gerald D.; Weinreb, Steven M.

    2006-01-01

    An efficient synthetic strategy for installation of the two vicinal quaternary carbon centers of the communesins is reported. Key steps include the O-allylation/Claisen rearrangement of spirolactone systems, which are formed by tandem intramolecular Heck cyclization/carbonylation. Substituent and solvent effects on the stereochemical outcome of the Claisen rearrangements have been examined. The stereochemical assignment of the allyl spirolactone previously reported as 17 has now been revised ...

  11. Possible reasons for anomalous fading in alkali feldspars used for luminescence dating of Quaternary deposits

    OpenAIRE

    Jaek, Ivar; Molodkov, Anatoli; Vasilchenko, Valery

    2007-01-01

    According to many publications, alkali feldspars are characterized by specific athermal (anomalous) fading of their thermoluminescence and optically-stimulated luminescence. This phenomenon is manifested as spontaneous decline in luminescence intensity over relatively long (months and years) time after laboratory irradiation, possibly due to tunnelling of electrons from lattice defects and impurities acting as dosimetric traps. It can hamper reliable luminescent dating of Quaternary deposits ...

  12. Abundance and size variation of Globorotalia menardii in the Northeastern Indian Ocean during the Late Quaternary

    Digital Repository Service at National Institute of Oceanography (India)

    Bhonsale, S.; Saraswat, R.

    reconstructions. Palaeogeogra., Palaeoclimatol., Palaeoecol. 160, 193-212. Kennett, J.P., Huddlestun, P., 1972. Late Pleistocene paleoclimatology, foraminiferal biostratigraphy and tephrochronology, western Gulf of Mexico. Quat. Res. 2, 3-9. Knappertsbusch, M... monsoon 2001. Deep-Sea Res. 50, 881-896. Malmgren, B., Healy-Williams, N., 1978. Variation in test diameter of Orbulina universa in the paleoclimatology of the late Quaternary of the Gulf of Mexico. Palaeogeogra., Palaeoclimatol., Palaeoecol. 25, 235...

  13. Novel low melting point quaternary eutectic system for solar thermal energy storage

    International Nuclear Information System (INIS)

    Highlights: ► Novel LiNO3–NaNO3–KNO3–NaNO2 system with melting point of 392.17 K was developed. ► The mixture showed excellent heat capacity. ► The mixture showed excellent short-term thermal stability. ► The mixture showed excellent energy storage capacity. -- Abstract: A new low melting point quaternary eutectic mixture consisting of alkali nitrates and sodium nitrite was modeled by using thermodynamic principles. The eutectic temperature of the quaternary salt mixture was predicted to be 371.75 K. The quaternary eutectic mixture was synthesized based on the predicted eutectic composition and the eutectic temperature was determined using the Differential Scanning Calorimeter (DSC). The experimental melting point was 372.17 K which was in excellent agreement with that of the predicted value. The heat capacity of the eutectic mixture was determined by the DSC as function of temperature in the liquid state and heat capacity increased with increase in temperature. Density of the molten quaternary eutectic mixture decreases linearly with increase in temperature. Thermal stability of the eutectic mixture was determined by both short-term and long-term thermogravimetric analyses. Short-term thermal stability test showed negligible weight loss. However, 7.4 wt.% weight loss was observed in the long–term thermal stability test at 773.15 K which corresponds to thermal decomposition of the salt mixture. Upper temperature limit for long-term thermal stability of the eutectic mixture was determined to be 703.15 K. Thermal energy storage capacity of the novel eutectic mixture was found to be larger than that of conventional solar salt and HITEC® salt.

  14. Quaternary sedimentation and active faulting along the Ecuadorian shelf : preliminary results of the ATACAMES Cruise (2012)

    OpenAIRE

    Michaud, François; Proust, J. N.; Collot, Jean-Yves; Lebrun, J.F.; De Witt, C.; Ratzov, G.; H. Pouderoux; Martillo, C.; Hernandez, M.J.; Loayza, G.; Penafiel, L.; Schenini, Laure; Dano, A.; Gonzalez, M; Barba, D

    2015-01-01

    Selected high-resolution seismic-reflection profiles and multibeam bathymetry acquired along the convergent Ecuador margin during the ATACAMES cruise on onboard the R/V L'Atalante (Jan.15-Feb.18, 2012) allow a preliminary evaluation of the neotectonic development and stratigraphic evolution of the margin based on the sismo-stratigraphic analysis of Quaternary sediment preserved on the margin shelf and upper slope. We present three major preliminary results. (1) The evolution of the Esmeraldas...

  15. The Occurrence of Vitric Tuff in Quaternary Deposits of Gljev in Dalmatia (Southern Croatia)

    OpenAIRE

    Šušnjara, M.; Šćavnićar, B.; Gabrić, A.

    1994-01-01

    For the first time in the Dinaric region of Dalmatia vitric tuff has been discovered in the clayey Quaternary deposits. Petrographic, heavy mineral and X-ray analyses revealed fine volcanic ash, illitic material (as an alteration product of glass shards), rare feldspar grains and an abundance of monoclinic pyroxene in the heavy mineral fraction. Pyroclastic quartz grains were not observed. It is postulated that explosive volcanism of basic or neutro-basic character occured and the finest part...

  16. Spontaneous quaternary and tertiary T-R transitions of human hemoglobin in molecular dynamics simulation.

    Directory of Open Access Journals (Sweden)

    Jochen S Hub

    2010-05-01

    Full Text Available We present molecular dynamics simulations of unliganded human hemoglobin (Hb A under physiological conditions, starting from the R, R2, and T state. The simulations were carried out with protonated and deprotonated HC3 histidines His(beta146, and they sum up to a total length of 5.6 micros. We observe spontaneous and reproducible T-->R quaternary transitions of the Hb tetramer and tertiary transitions of the alpha and beta subunits, as detected from principal component projections, from an RMSD measure, and from rigid body rotation analysis. The simulations reveal a marked asymmetry between the alpha and beta subunits. Using the mutual information as correlation measure, we find that the beta subunits are substantially more strongly linked to the quaternary transition than the alpha subunits. In addition, the tertiary populations of the alpha and beta subunits differ substantially, with the beta subunits showing a tendency towards R, and the alpha subunits showing a tendency towards T. Based on the simulation results, we present a transition pathway for coupled quaternary and tertiary transitions between the R and T conformations of Hb.

  17. Extraction of tetravalent berkelium and cerium by aliquate-336-S-NO3 quaternary ammonium salt

    International Nuclear Information System (INIS)

    Extraction of tetravalent berkelium and cerium by aliquate-336-S-NO3 quaternary ammonium salt from nitric acid solutions is investigated. The effect of concentrations of nitric acid and extracting agent, nature of an oxidant (potassium bromate, potassium bichromate, mixture of AgNO3 and (NH4)2S2O8) and solvent on the distribution coefficient of berkelium(4) and cerium(4) is studied. It is established that solutions of aliquate-336-S-NO3 in carbon tetrachloride and dichloroethane extract quantitatively tetravalent berkelium from 10-12 M nitric acid solutions and cerium - from 1-10 M nitric acid solutions containing potassium bichromate as an oxidant. It is shown that the value of distribution coefficient for berkelium and cerium depends on the nature of an oxidant and extracting agent concentration. It is established that in the case of extraction by quaternary ammonium salt with one berkelium(4) mole four aliquate-336-SNO3 moles are associated and 1.5-1.6 mole of extracting agent are associated with one cerium(4) mole. It permits to make a conclusion that stoichiometry of extraction reactions by quaternary ammonium salt is not the same for tetravalent berkelium and cerium. It is shown that trivalent transplutonium and rare earth elements are not practically extracted by aliquate-336-S-NO3 from nitric acid solutions

  18. Evaluation of quaternary ammonium halides for removal of methyl iodide from flowing air streams

    International Nuclear Information System (INIS)

    The quaternary ammonium halides of several tertiary amines were used as impregnants on activated carbon and were tested for methyl iodide penetration in accordance with test Method A, ASTM D3803, 1979, ''Standard Test Methods for Radio-iodine Testing of Nuclear Grade Gas Phase Adsorbents''. The results suggest that the primary removal mechanism for methyl iodide-131 is isotopic exchange with the quaternary ammonium halide. For example, a 5 wt% impregnation of each of the tetramethyl, tetraethyl, tetrapropyl and tetrabutyl ammonium iodides on activated carbon yielded percent penetrations of 0.47, 0.53, 0.78, and 0.08 respectively when tested according to Method A of ASTM D3803. A sample impregnated with 5% tetramethyl ammonium hydroxide gave a methyl iodide penetration of 64.87%, thus supporting the isotopic exchange mechanism for removal. It has been a generally held belief that the success of tertiary amines as impregnants for radioiodine removal is a result of their ability to complex with the methyl iodide. The results of the work indicates that the superiority of the tertiary amines similar to triethylene diamine and quinuclidine, when compared to their straight chain analogs, is a result of their ease in reacting with methyl iodide-127 to form the quaternary ammonium iodide followed by isotopic exchange

  19. Role of Growth Faulting in the Quaternary Development of Mississippi-River Delta

    Science.gov (United States)

    Mohrig, D.; George, T. J.; Straub, K. M.

    2008-12-01

    We use an industry grade seismic volume and observations of present-day surface topography to resolve the influence of growth faulting on evolution of Mississippi delta in southeastern Louisiana from the Pleistocene to Recent. The volume of seismic data covers an area roughly 1400 square kilometers in size and it resolves many normal faults with displacements that can be tied to movement of Jurassic Louann Salt in the subsurface. We have defined the Quaternary activity associated with 6 of these normal faults by measuring the progressive offset of strata deposited on the delta surface over time. These measurements of fault displacement were restricted to the sedimentary section positioned 150 to 1500 m beneath the delta surface. Total vertical offsets measured within this Quaternary section range from 60 to 150 m. These fault displacements represent abrupt spatial variations in subsidence rate that are between 4 and 8 percent of the regional, long-term deposition rate. Our best estimates for the Quaternary rates of fault displacement vary between 0.1 and 1 mm/yr. Five faults can be connected to deformation of the modern delta surface. Wetland on the footwall is replaced by open water on the hanging wall of these structures. In spite of this evidence for modern surface deformation, the orientations of buried, seismically resolved channel bodies do not appear to be affected by the positions of active growth faults. We will evaluate the competition between subsidence and sedimentation patterns that leads to this style of channelized stratigraphy.

  20. Quaternary Geology and Geomorphology of Terna River Basin in West Central India

    Directory of Open Access Journals (Sweden)

    Mohammad Babar

    2012-12-01

    Full Text Available This paper presents the morphostratigraphy, lithostratigraphy and sedimentary structures of Terna River basin in the Deccan Basaltic Province (DBP of West Central India. These Quaternary deposits have been divided into three informal formations (i dark grey silt formation – Late Holocene, (ii Light grey silt formations – Early Holocene, (iii Dark grayish brown silt formation – Late Pleistocene with the older Quaternary Alluvial deposits of Upper Pleistocene age. The fine clay and silt formations in the lower reaches reflect that the streams are of low gradient and more sinuous. The river shows evidences of channel movement by avulsion, largely controlled by lineaments. Palaeo-levees, in the form 4–5 m high ridges exist along the Terna River floodplain, specifically in the Ter, Killari, Sastur, Dhuta and Makni villages. Several lineaments occur along NE-SW, NW-SE, E-W and WNW-ESE directions, which control the basement structure in the study area. The values of the Topographic Sinuosity Index (TSI indicate rejuvenation of the area leading to the dominance of topography on the sinuosity of the river channels. The break in slope in the long profile is also indication of the Quaternary tectonic uplift of the area. Radiocarbon dating of some charcoal fragments collected from folded beddings indicates that paleoseismic activity might have taken place along the basin between AD 120 and AD 1671.

  1. The diversity in thermal behavior of novel catanionic cholates: The dominant effect of quaternary ammonium centers

    Energy Technology Data Exchange (ETDEWEB)

    Mihelj, Tea, E-mail: tmihelj@irb.hr [Department of Physical Chemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb (Croatia); Vojta, Danijela [Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb (Croatia); Tomašić, Vlasta [Department of Physical Chemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb (Croatia)

    2014-05-01

    Graphical abstract: - Highlights: • Quaternary ammonium cholates characterized as crystal smectics at room temperature. • The domination of quaternary ammonium center seen through diverse thermal behavior. • Thermal changes of cholates keto–enol balance results with prevalence of one form. • Polynomial regression of isotropisation temperatures vs. dodecyl chain number. • Linear descending trend of isotropisation temperatures with higher headgroup number. - Abstract: The thermal behavior of novel catanionic compounds based on cholate anion was examined. The study explains the effect of the raising dodecyl chain number, as well as of the raising headgroup number in quaternary ammonium salts on their physico-chemical properties. The examined samples are crystal smectic phases at room temperature. Their rich and diverse thermal behavior is seen through polymorphic phase transitions, thermotropic mesomorphism of smectic nature and in some cases, kinetically managed crystallization that lasts in days. The changes of the cholates keto–enol isomer balance during thermal treatment are obtained. For both groups of samples temperatures of isotropisation and the thermodynamic parameters follow polynomial regression. Introduction of the new dodecyl chain leads to more ordered structure, while implementation the new headgroup leads to advanced polymer-like structure. The obtained results demonstrate an effort for getting and controlling the regularity of the physico-chemical and thermotropic properties for new compounds by systematic changing of cationic part of the molecule. These informations could provide in the future the easiest way for selection of potentially new and targeted applicable materials.

  2. The diversity in thermal behavior of novel catanionic cholates: The dominant effect of quaternary ammonium centers

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Quaternary ammonium cholates characterized as crystal smectics at room temperature. • The domination of quaternary ammonium center seen through diverse thermal behavior. • Thermal changes of cholates keto–enol balance results with prevalence of one form. • Polynomial regression of isotropisation temperatures vs. dodecyl chain number. • Linear descending trend of isotropisation temperatures with higher headgroup number. - Abstract: The thermal behavior of novel catanionic compounds based on cholate anion was examined. The study explains the effect of the raising dodecyl chain number, as well as of the raising headgroup number in quaternary ammonium salts on their physico-chemical properties. The examined samples are crystal smectic phases at room temperature. Their rich and diverse thermal behavior is seen through polymorphic phase transitions, thermotropic mesomorphism of smectic nature and in some cases, kinetically managed crystallization that lasts in days. The changes of the cholates keto–enol isomer balance during thermal treatment are obtained. For both groups of samples temperatures of isotropisation and the thermodynamic parameters follow polynomial regression. Introduction of the new dodecyl chain leads to more ordered structure, while implementation the new headgroup leads to advanced polymer-like structure. The obtained results demonstrate an effort for getting and controlling the regularity of the physico-chemical and thermotropic properties for new compounds by systematic changing of cationic part of the molecule. These informations could provide in the future the easiest way for selection of potentially new and targeted applicable materials

  3. A study of the formation constants of ternary and quaternary complexes of some bivalent transition metals

    Directory of Open Access Journals (Sweden)

    MADHURJYA NEOG

    2010-01-01

    Full Text Available The formation of hetero-ligand 1:1:1, M(II-Opda-Sal/Gly ternary and 1:1:1:1, M(II-Opda-Sal-Gly quaternary complexes, where M(II = Ni, Cu, Zn and Cd; Opda = o‑phenylenediamine, Sal = salicylic acid, Gly = glycine, was studied pH-metrically in aqueous medium. The formation constants for the resulting ternary and quaternary complexes were evaluated at a constant ionic strength, μ = 0.20 mol dm-3 and temperature, 30±0.1 °C. The order of the formation constants in terms of the metal ion for both type of complexes was found to be Cu(II > Ni(II > Zn(II > Cd(II. This order was explained based on the increasing number of fused rings, the coordination number of the metal ions, the Irving – William order and the stability of various species. The expected species formed in solution were pruned with the Fortran IV program SPEPLOT and the stability of the ternary and quaternary complexes is explained.

  4. Properties of true quaternary fission of nuclei with allowance for its multistep and sequential character

    International Nuclear Information System (INIS)

    An analysis of basicmechanisms of binary and ternary fission of nuclei led to the conclusion that true ternary and quaternary fission of nuclei has a sequential two-step (three-step) character, where, at the first step, a fissile nucleus emits a third light particle (third and fourth light particles) under shakeup effects associated with a nonadiabatic character of its collective deformation motion, whereupon the residual nucleus undergoes fission to two fission fragments. Owing to this, the formulas derived earlier for the widths with respect to sequential two- and three-step decays of nuclei in constructing the theory of two-step twoproton decays and multistep decays in chains of genetically related nuclei could be used to describe the relative yields and angular and energy distributions of third and fourth light particles emitted in (α, α), (t, t), and (α, t) pairs upon the true quaternary spontaneous fission of 252Cf and thermal-neutron-induced fission of 235U and 233U target nuclei. Mechanisms that explain a sharp decrease in the yield of particles appearing second in time and entering into the composition of light-particle pairs that originate from true quaternary fission of nuclei in relation to the yields of analogous particles in true ternary fission of nuclei are proposed

  5. Quaternary transgressive and regressive depositional sequences in the East China Sea

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Based on the interpretation more than 4000 km sparker single channel seismic profiles and the comparison with Borehole DZQ4 on the outer shelf of the East China Sea (ECS), the seismic sequences, sedimentary facies and paleo-sedimentary environment are studied to establish the chronology framework and discuss the Quaternary transgressive and regressive sequences of the ECS shelf as well as their response to glacio-eustatic sea-level changes. The sea level of the ECS fluctuated with global climate changes in the Quaternary. During the sea level rise, the Pacific tidal wave impacted actively on the ECS continental shelf and the reciprocating tidal currents in NW-SE direction formed tidal sand ridges, which represent large transgressive deposits visible on the seismic profiles. In response to sea level fall, the Yangtze River deltas prograded seaward and built massive subaqueous deltas to form regressive sequences on the seismic profiles. Alternative transgression and regression sequences were vertically distributed on the ECS shelf with the frequent eustacy in the Quaternary. The gentle slope of the ECS shelf makes it possible for the coastline to migrate hundreds of kilometers forth and back on the shelf because of tens of meters sea level changes, in the meanwhile, the Yangtze River discharged large amounts of sediments into the ECS resulting in large-scale subaqueous deltas and tidal sand ridges. There have developed 3 stages of tidal sand ridges and 4 stages of deltas on the ECS shelf since oxygen isotope stage 8.

  6. Flotation and adsorption of quaternary ammonium salts collectors on kaolinite of different particle size

    Institute of Scientific and Technical Information of China (English)

    Jiang Hao; Liu Guorong; Hu Yuehua; Xu Longhua; Yu Yawen; Xie Zhen; Chen Haochuan

    2013-01-01

    The flotation behaviors of decyltrimethylammonium (103C),dodecyltrimethylammonium chloride (DTAC),tetradecyltrimethylammonium chloride (TTAC) and cetyltrimethylammonium chloride (CTAC) on kaolinite of different particle size fraction were studied.The adsorbed amount and adsorption isotherms of collectors on kaolinite were determined for painstaking investigation into the adsorption of quaternary amines at kaolinite-water interface by ultraviolet spectrophotometer methods.The flotation results show that the flotation recovery of kaolinite of different particle fraction increases with an increase in pH when 103C,DTAC,TrAC and CTAC are used as collectors.As the concentration of collectors increases,the flotation recovery increases.Particle size of kaolinite has a strong effect on flotation.The flotation recovery of fine kaolinite decreases with the carbon chain of quaternary ammonium salts collectors increasing,while coarse kaolinite is on the contrary.The adsorbed amount tests and adsorption isotherms show that adsorbed amount increases when the particle size of kaolinite increases or when the carbon chain length of quaternary ammonium salts increases.Within the range of flotation collector concentration,the longer the hydrocarbon chain,the more probable to be absolutely adsorbed by fine kaolinite particles and then the lower the collector concentration in the bulk,which leds to lower flotation recovery.

  7. Late Quaternary tephrostratigraphy from the southern Havre Trough - Bay of Plenty, northeast New Zealand

    International Nuclear Information System (INIS)

    A number of late Quaternary subaerial silicic tephra erupted from the Taupo Volcanic Zone are dispersed at least 230 km to the northeast of New Zealand, and are deposited as predominantly airfall vitric ash; other tephra are recognised as reworked ash turbidites. Tephra occurring as both megascopic and nonmegascopic ash within three piston cores from the Bay of Plenty - southern Havre Trough are used to establish a c.55 ka old marine tephrostratigraphy. On the basis of core stratigraphy, 14C dating, glass chemistry, and ferromagnesian mineralogy, the Kaharoa, Taupo, Mamaku, Waiohau, ?Okareka, Kawakawa, Omataroa, Hauparu, Tahuna, and ?Rotoehu tephras are identified between 160 and 350 km from source. Peralkaline tephra from previously unrecognised Mayor Island eruptions are identified at c. 30 and 55 ka, and possibly 11.5 ka. Other tephra comprising pumiceous ash-lapilli, and low SiO2 silicic glass, are also identified, but cannot be reliably correlated to a volcanic centre source. Occasional shards of andesitic and dacitic composition are probably largely derived from White Island eruptions. Provisional northerly seaward limits of airfall dispersal are presented for nine late Quaternary silicic tephra. Within the Bay of Plenty region, the c. 36 ka Hauparu Tephra has an extensive distribution comparable to that of the c. 22.6 ka Kawakawa Tephra, and hence forms an important offshore late Quaternary stratigraphic horizon. (author). 37 refs., 7 figs., 7 tabs

  8. Origin of Bermuda's clay-rich Quaternary paleosols and their paleoclimatic significance

    Science.gov (United States)

    Herwitz, S.R.; Muhs, D.R.; Prospero, J.M.; Mahan, S.; Vaughn, B.

    1996-01-01

    Red clayey paleosols that are chiefly the product of aerosolic dust deposition are interbedded in the Quaternary carbonate formations of the Bermuda oceanic island system. These paleosols provide a basis for reconstructing Quaternary atmospheric circulation patterns in the northwestern Atlantic. Geochemical analyses were performed on representative paleosol samples to identify their parent dust source. Fine-grained fractions were analyzed by energy-dispersive X ray fluorescence to determine trace element (Zr, Y, La, Ti, and Nb) concentrations and to derive geochemical signatures based on immobile element ratios. These ratios were compared with geochemical signatures determined for three possible sources of airborne dust: (1) Great Plains loess, (2) Mississippi River Valley loess, and (3) Saharan dust. The Zr/Y and Zr/La ratios provided the clearest distinction between the hypothesized dust sources. The low ratios in the paleosol B horizons most closely resemble Saharan dust in the Bermuda paleosols have a predominantly Saharan aerosolic dust signature. Saharan dust deposition on Bermuda during successive Quaternary glacial periods is consistent with patterns of general circulation models, which indicate that during glacial maxima the northeast summer trade winds were stronger than at present and reached latitudes higher than 30 ?? N despite lower-than-present sea surface temperatures in the North Atlantic.

  9. The Heidelberg Basin Drilling Project - Sedimentology and Stratigraphy of the Quaternary succession

    Science.gov (United States)

    Ellwanger, Dietrich; Gabriel, Gerald; Hahne, Jürgen; Hoselmann, Christian; Menzies, John; Simon, Theo; Weidenfeller, Michael; Wielandt-Schuster, Ulrike

    2010-05-01

    Within the context of the Heidelberg Basin Drilling Project (Gabriel et al. 2008), a detailed sediment succession is presented here based upon deep drillings taken at Heidelberg UniNord and Mannheim Käfertal. Sediment structures, and micromorphological and pollen analyses were conducted and used to reconsider some of the climate transitions within the lower Pleistocene. A new and novel scenario is postulated regarding the preservation of Quaternary sediment packages within the Cenozoic Graben environment of the Heidelberg basin. The palynological evidence comprises the periods of warm climate of the Holsteinian (mainly Abies (fir), some Fagus (beech), Pterocarya & Azolla); the Cromerian (Pinus-Picea-QM (pine-spruce-QM)); the Bavelian (Abies, Tsuga (hemlock fir), QM & phases of increased NAP including Pinus); the Waalian (Abies, Tsuga, QM); and the Tiglian (Fagus & early Pleistocene taxa especially Sciadopytis, downward increasing Tertiary taxa). The sediment package was studied both macroscopically and microscopically. Both techniques provide evidence of fluvial, lacustrine and mass movement sedimentary processes. Some include evidence of periglacial processes (silt droplets within fine grained sands indicative of frozen ground conditions). The periglacial structures are often, not always, accompanied by pollen spectra dominated by pine and NAP. E.g. the Tiglian part of the succession shows periglacial sediment structures at its base and top but not in its middle sections. I.e. it appears not as a series of warm and cold phases but rather as a constant warm period with warm-cold-alternations at its bottom and top. All results illustrate sediment preservation in the Heidelberg basin almost throughout the Quaternary. This may be due to tectonic subsidence, but also to compaction by sediment loading of underlying fine sediments (Oligocene to Quaternary) leading to incomplete but virtually continuous sediment preservation (Tanner et al. 2009). References Gabriel, G

  10. The New ILP Database of Quaternary Faults and Folds in South America

    Science.gov (United States)

    Costa, C. H.; Cisneros, H. A.; Machette, M. N.; Dart, R. L.

    2003-12-01

    As part of the International Lithosphere Program's Task Group II-2, we have completed the compilation of Quaternary faults and folds in South America and have established an Internet website for this data. The underpinning maps and reports have been released as electronic U.S. Geological Survey Open-File Reports (pdfs, see poster). The maps show the location, time, sense of slip, and activity rate of major earthquake-related features such as faults and fault-related folds. The maps are accompanied by descriptions of their Quaternary activity. The primary elements of the 10-year project are supervision and interpretation of geologic/tectonic information (Costa and Machette), data compilation (project participants), database design and management (Cisneros), and GIS input and management (Dart). A dozen experts in Quaternary faulting, neotectonics, paleoseismology, and seismology compiled the data: questions about individual faults or additions to the database should be directed to them. Prior to this project, digital maps of Quaternary faults did not exist for any of the South America countries, even though understanding the extent and character of active and older Quaternary faults are critical elements of seismic-hazards analysis. These new data will help extend the relatively short record of instrumental and felt seismicity that is the primary parameter for current seismic-hazard assessments in South American countries. Although some fault data were available for most of the countries (i.e., Venezuela), the degree of completeness varies as a function of the remoteness and vegetation cover (i.e., Brazil). A few faults such as the Bocono have had detailed investigations involving modern paleoseismic techniques. Other faults have been studied in some detail, usually in association with concerns about hazards to urban areas or the safety of critical facilities such as mining operations, oil-and-gas pipelines, or power-generating facilities. However, the general state

  11. Quaternary nanofossils on the Brazilian continental shelf; Nanofosseis calcarios do quaternario da margem continental brasileira

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, Rogerio Loureiro [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Gerencia de Bioestratigrafia e Paleoecologia], E-mail: rlantunes@petrobras.com.br

    2007-07-01

    The study of calcareous nanofossils occurring in the deposits on the Brazilian continental margin began in the late 1960s, undertaken solely by PETROBRAS. Instead of presenting an academic outlook, the purpose of these investigations is first to formulate a biostratigraphic framework to apply to oil well samples. The initial result was the first zoning for the Brazilian continental margin, which considered the deposits formed between the Aptian and Miocene series. Since the 1960s to date, many papers have been written either with details of that original zoning or applying nanofossil biostratigraphy to solve stratigraphic problems. Regardless of all the papers and studies undertaken, little attention has been paid to the Quaternary, since these deposits are normally of no interest to petroleum geology stricto sensu, especially in a large part of the Brazilian margin. On the other hand, there are a few articles and some Master's dissertations and PhD theses that were written and/or are in progress in Brazilian universities. On the other hand, elsewhere in the world, Quaternary nanofossils have been thoroughly investigated in terms of biostratigraphy and paleoceanography. It is, therefore, very clear that there is a gap between what is being done elsewhere in the world and what has been done in Brazil. In fact, this gap is not larger simply because of a few researchers in Brazilian universities who are studying this topic. The intention of this paper is to contribute toward a richer study of Quaternary nanofossils. It, therefore, contains illustrations and taxonomic descriptions of many species observed in the younger strata of the Brazilian margin basins. This article not only aspires to portray and disseminate the potential of nanofossils for the marine Quaternary study but is also an invitation to students (under and post-graduates) and university researchers - an invitation to learn a little more about the subject and spend some time studying these real gems

  12. Diastereoselective Synthesis of and Mechanistic Understanding for the Formation of 2-Piperidinones from Imines and Cyano-Substituted Anhydrides.

    Science.gov (United States)

    Di Maso, Michael J; Snyder, Kevin M; De Souza Fernandes, Fábio; Pattawong, Ommidala; Tan, Darlene Q; Fettinger, James C; Cheong, Paul Ha-Yeon; Shaw, Jared T

    2016-03-24

    2-Piperidinones are synthesized in a single step from imines and 2-cyano glutaric anhydrides. The reaction provides the products in good diastereoselectivity and generates a quaternary stereogenic center. Substitutions on the anhydride skeleton are well tolerated to provide 2-piperidinones with three stereogenic centers from a single transformation. The pertinent transition structures have also been computed using quantum mechanics and reveal the key interactions controlling the stereochemical outcome of the reaction. PMID:26929008

  13. An Overview of the Main Quaternary Deformation of South America Una perspectiva sobre las principales deformaciones cuaternarias de América del Sur

    OpenAIRE

    C.H. Costa; F.A. Audemard M.; F.H.R. Bezerra; A. Lavenu; M.N. Machette; G. París

    2006-01-01

    Deformation affecting continental South America during Quaternary is related to the Neogene geodynamic processes. These structures are mainly controlled by anisotropies inherited after a long and complex history as well as by the kinematic and geometric features of the ongoing plate interaction. Main Quaternary structures at both ends of South America are directly linked to plate interaction and some of them are considered to be plate boundaries. The main structures with Quaternary activity a...

  14. Quantitative assessment of radionuclide retention in the Quaternary sediments/granite interface of the Fennoscandian shield (Sweden)

    Energy Technology Data Exchange (ETDEWEB)

    Grandia, Fidel [Amphos XXI Consulting S.L., Passeig de Garcia i Faria, 49-51, 1o-1a - E08019, Barcelona (Spain); Sena, Clara, E-mail: csena@ua.pt [Amphos XXI Consulting S.L., Passeig de Garcia i Faria, 49-51, 1o-1a - E08019, Barcelona (Spain)] [I and DGeoBioTec, Geosciences Dept., University of Aveiro, 3810-193 Aveiro (Portugal); Arcos, David; Molinero, Jorge; Duro, Lara; Bruno, Jordi [Amphos XXI Consulting S.L., Passeig de Garcia i Faria, 49-51, 1o-1a - E08019, Barcelona (Spain)

    2011-05-15

    Highlights: > The release of radionuclides from a deep geological repository is investigated. > We simulate the transport of radionuclides in a Quaternary sediment. > The Quaternary sediment's geochemistry is studied to select the reactive minerals. > U, Sr, Cs and Ra were selected due to their contribution for the radioactive dose. > The retention capacity of the Quaternary sediments was quantitatively evaluated. - Abstract: The Quaternary sediments representing the interface between the granite host rock and the Earth surface are of paramount importance when determining the potential cycling of anthropogenic and natural radionuclides in near-surface systems. This is particularly true in the case of high-level nuclear waste (HLNW) repositories placed in granite. In this work a modelling procedure is presented to quantitatively determine the retention capacity of a Quaternary till in the Forsmark area, which has been recently selected to host the deep geologic storage of HLNW in Sweden. Reactive transport numerical models have been used to simulate the intrusion of a deep groundwater carrying radionuclides potentially released from a repository into a Quaternary till. Four radionuclides ({sup 235}U, {sup 135}Cs, {sup 226}Ra and {sup 90}Sr) have been selected according to their different geochemical behaviour and potential dose relevance to surface ecosystems. Numerical results indicate that repository-derived: (i) U will have a minor impact in the till, mainly due to the high natural concentration of U and its adsorption on ferrihydrite; (ii) Cs will be efficiently retained by cation exchange on illite; (iii) Ra will be retained via co-precipitation with barite; and although (iv) Sr will be retained via co-precipitation with calcite and cation exchange on illite, the retention capacity of the Quaternary till for Sr is limited.

  15. Mapping the North Sea base-Quaternary: using 3D seismic to fill a gap in the geological record

    Science.gov (United States)

    Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

    2014-05-01

    The identification and mapping of the base-Quaternary boundary in the central parts of the North Sea is problematic due to the change from an unconformable transition between Pliocene and Pleistocene deltaic deposits in the southern North Sea to a conformable one further north (Sejrup et al 1991; Gatliff et al 1994). The best estimates of the transition use seismic reflection data to identify a 'crenulated reflector' (Buckley 2012), or rely on correlating sparse biostratigraphy (Cameron et al 1987). Recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) allows greater confidence in the correlation to a regional 3D seismic dataset and show that the base-Quaternary can be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The mapped horizon is presented here alongside the difference between this new interpretation and the previously interpreted base-Quaternary (Buckley 2012). The revised base-Quaternary surface reaches a depth of 1248 ms TWT or approximately 1120 m (assuming average velocity of 1800 m/s) showing an elongate basin shape that follows the underlying structure of the Central Graben. The difference between the revised base-Quaternary and the traditional base-Quaternary reaches a maximum of over 600 ms TWT or approximately 540 m in the south-west with over 300 ms TWT or approximately 270 m at the Josephine well (56° 36.11'N, 2° 27.09'E) in the centre of the basin. Mapping this new base-Quaternary allows for the interpretation of the paleo-envionrment during the earliest Quaternary. Seismic attribute analysis indicates a deep water basin with sediment deposition from multiple deltas and redistribution by deep

  16. Versatile methods for synthesizing organic acid salts of quaternary berberine-type alkaloids as anti-ulcerative colitis agents.

    Science.gov (United States)

    Zhang, Zhi-Hui; Li, Jing; Zhang, Hai-Jing; Deng, An-Jun; Wu, Lian-Qiu; Li, Zhi-Hong; Song, Hong-Rui; Wang, Wen-Jie; Qin, Hai-Lin

    2016-06-01

    Two versatile methods to synthesize kinds of organic acid salts of quaternary berberine-type alkaloids were investigated in order to determine which is more efficient to improve the liposolubility of the target compounds and to explore the efficacy of the target compounds as anti-ulcerative colitis (UC) agents. Overall evaluation according to the reaction results and yields of the final products indicated that the synthetic method using tertiary (±)-8-acylmethyldihydroberberine-type alkaloids as key intermediates is superior to that of using tertiary dihydroberberine-type alkaloids as intermediates. Ten target compounds were synthesized using quaternary berberine chloride and quaternary coptisine chloride as starting materials, respectively, and the anti-UC activity of some target compounds was evaluated in an in vitro x-box-binding protein 1 (XBP1) transcriptional activity assay using dual luciferase reporter detection. At 10 μM, the tested compounds were found to activate the transcription of XBP1 target at almost the same level as that of quaternary coptisine chloride. The synthesized target compounds were also found to share higher liposolubility than the inorganic acid salts of quaternary berberine-type alkaloid. PMID:27097666

  17. Thermoluminescence and new 14C age estimates for late quaternary loesses in southwestern Nebraska

    Science.gov (United States)

    Maat, P.B.; Johnson, W.C.

    1996-01-01

    Loess of late Quaternary age mantles most of Nebraska south of the Platte River Valley. At least five late Quaternary loesses are recognized: from oldest to youngest, one or more undifferentiated pre-lllinoian loesses, the Loveland Loess, the Gilman Canyon Loess, which exhibits a well developed soil and rests unconformably on the Sangamon soil, the Peoria Loess capped by the Brady soil, and the Bignell Loess, which is distributed discontinuously. Previous research shows that the Loveland Loess is Illinoian. the Gilman Canyon Loess and Peoria Loess are Wisconsin, and the Bignell Loess is Holocene. We present here the first thermoluminescence (TL) age estimates and new C ages for these late Quaternary loesses at two key sections in southwestern Nebraska, the Eustis ash pit and the Bignell Hill road cut. TL age estimates from all samples collected from Eustis ash pit and Bignell Hill were internally consistent. TL and C age estimates from these two sections generally agree and support previous age determinations. The TL age estimate on Loveland Loess indicates deposition at 163 ka. TL and radiocarbon age estimates indicate that Oilman Canyon Loess, believed to be deposited during the Farmdale interstade, first began to accumulate at about 40 ka: the lower part of the Gilman Canyon Loess is 36 ka at Eustis and the middle of the unit is 30 ka at Bignell Hill. The lower and upper parts of the Peoria Loess give age estimates of 24 ka and 17 ka, respectively. TL age estimates for deposition of the Bignell Loess are 9 ka near the base, in agreement with radiocarbon age estimates, and 6 ka immediately below the modern soil, substantiating its Holocene age. Comparisons of TL age estimates with ??18O and insolation curves which show loess deposition during interglacial and interstadial as well as glacial periods, indicate that loess deposition on the Great Plains can occur under a variety of climatic conditions.

  18. Quaternary Geomagnetic Paleointensity from IODP Site U1308 (IODP Expedition 303)

    Science.gov (United States)

    Channell, J. E.; Mazaud, A.; Stoner, J. S.; Scientific Party, I. Class='hr'>

    2006-05-01

    The primary objective of IODP Expedition 303 (Sept.-Nov., 2004) was to recover complete and continuous records of Pliocene-Quaternary millennial-scale environmental and geomagnetic variability, and place these records into high-resolution isotopic and magnetic stratigraphies (including relative paleointensity). One of the North Atlantic sites drilled during Exp. 303 (Site U1308) was a re-drill of DSDP Site 609. This site has played an important role in documentation of marine records of suborbital climate variability for the last climate cycle, and the goal at Site U1308 is to extend the records back through the Quaternary and into the Pliocene. Paleomagnetic data from IODP Site U1308 have been acquired from u-channel samples collected down to a depth below seafloor of 175 m, representing the last 2.3 Myrs. The magnetic polarity stratigraphy is unambiguous, and yields a mean sedimentation rate of 7.6 cm/kyr. The relatively low sedimentation rates (compared to North Atlantic drift sites) may account for the fact that only one interval of excursional directions is observed in the u-channel data (the Punaruu Excursion between the Jaramillo and Cobb Mt. Subchrons). Paleointensity proxies are based on natural remanent magnetization normalized by anhysteretic remanence (ARM) and isothermal remanence (IRM). The normalization has been carried out for both demagnetized ARM, and for progressive ARM acquisition (the so-called pseudo-Thellier technique). The consistency among the paleointensity proxies, and uniformity in magnetic grain-size and concentration parameters, indicate that the proxies probably reflect geomagnetic field intensity. This conclusion is supported by comparison with other records of geomagnetic paleointensity that extend through the Quaternary, such as those from ODP Sites 983 and 984. The ultimate objective is to place climate-proxy data from Site U1308, such as detrital layer stratigraphy indicative of ice-sheet instability, into a chronostratigraphy

  19. Quantification of quaternary structure stability in aggregation-prone proteins under physiological conditions: the transthyretin case.

    Science.gov (United States)

    Robinson, Lei Z; Reixach, Natàlia

    2014-10-21

    The quaternary structure stability of proteins is typically studied under conditions that accelerate their aggregation/unfolding processes on convenient laboratory time scales. Such conditions include high temperature or pressure, chaotrope-mediated unfolding, or low or high pH. These approaches have the limitation of being nonphysiological and that the concentration of the protein in solution is changing as the reactions proceed. We describe a methodology to define the quaternary structure stability of the amyloidogenic homotetrameric protein transthyretin (TTR) under physiological conditions. This methodology expands from a described approach based on the measurement of the rate of subunit exchange of TTR with a tandem flag-tagged (FT₂) TTR counterpart. We demonstrate that subunit exchange of TTR with FT₂·TTR can be analyzed and quantified using a semi-native polyacrylamide gel electrophoresis technique. In addition, we biophysically characterized two FT₂·TTR variants derived from wild-type and the amyloidogenic variant Val122Ile TTR, both of which are associated with cardiac amyloid deposition late in life. The FT₂·TTR variants have similar amyloidogenic potential and similar thermodynamic and kinetic stabilities compared to those of their nontagged counterparts. We utilized the methodology to study the potential of the small molecule SOM0226, a repurposed drug under clinical development for the prevention and treatment of the TTR amyloidoses, to stabilize TTR. The results enabled us to characterize the binding energetics of SOM0226 to TTR. The described technique is well-suited to study the quaternary structure of other human aggregation-prone proteins under physiological conditions. PMID:25245430

  20. Quaternary ammonium biocides as antimicrobial agents protecting historical wood and brick.

    Science.gov (United States)

    Rajkowska, Katarzyna; Koziróg, Anna; Otlewska, Anna; Piotrowska, Małgorzata; Nowicka-Krawczyk, Paulina; Brycki, Bogumił; Kunicka-Styczyńska, Alina; Gutarowska, Beata

    2016-01-01

    Quaternary ammonium compounds (QACs) are widely used in disinfection of water, surfaces and instruments as well as in textile, leather and food industries because of their relatively low toxicity, broad antimicrobial spectrum, non-volatility and chemical stability. Due to these advantages, QACs are also used in restoration and can be applied on historical material. The aim of this study was to determine the usefulness of biocides based on quaternary ammonium salts and containing various excipients in the protection of historical materials against microbial growth. The study determined the antimicrobial activity of three biocides against bacteria: Pseudomonas fluorescens, Staphylococcus equorum, Bacillus cereus, Bacillus muralis, Sporosarcina aquimarina and Rhodococcus fascians, and moulds: Chaetomium globosum, Penicillium citreonigrum, Cladosporium cladosporioides I, Acremonium strictum, Aspergillus fumigatus and Cladosporium cladosporioides II, all isolated from historical wood and brick. Staphylococcus equorum, Bacillus cereus, Sporosarcina aquimarina and Rhodococcus fascians bacteria, and Cladosporium cladosporioides I and Acremonium strictum moulds showed high sensitivity to quaternary ammonium biocides. Historical wood can be effectively disinfected by three applications of biocide A (30% v/v) containing dodecyl dimethyl ammonium chloride (DDAC), citric acid, propiconazole and propanol. Disinfection of historical brick can be carried out by three applications of 6% v/v solutions of biocide B (based on DDAC and ethylenediaminetetraacetic acid - EDTA) or biocide C (containing a non-ionic surfactant, DDAC and EDTA). Effective protection of historical building materials against microbial growth for a period of seven days can be achieved by the application of biocide A (30% v/v) on the wood surface and biocide B (6% v/v) on the brick surface. PMID:26629794

  1. Quaternary polymethacrylate-magnesium aluminum silicate films: Water uptake kinetics and film permeability.

    Science.gov (United States)

    Rongthong, Thitiphorn; Sungthongjeen, Srisagul; Siepmann, Florence; Siepmann, Juergen; Pongjanyakul, Thaned

    2015-07-25

    The aim of this study was to investigate the impact of the addition of different amounts of magnesium aluminum silicate (MAS) to polymeric films based on quaternary polymethacrylates (QPMs, here Eudragit RS and RL). MAS contains negatively charged SiO(-) groups, while QPM contains positively charged quaternary ammonium groups. The basic idea is to be able to provide desired water and drug permeability by simply varying the amount of added MAS. Thin, free films of varying composition were prepared by casting and exposed to 0.1M HCl and pH 6.8 phosphate buffer. The water uptake kinetics and water vapor permeability of the systems were determined gravimetrically. The transport of propranolol HCl, acetaminophen, methyl-, ethyl- and propylparaben across thin films was studied using side-by-side diffusion cells. A numerical solution of Fick's second law of diffusion was applied to determine the apparent compound diffusion coefficients, partition coefficients between the bulk fluids and the films as well as the apparent film permeability for these compounds. The addition of MAS resulted in denser inner film structures, at least partially due to ionic interactions between the positively charged quaternary ammonium groups and the negatively charged SiO(-) groups. This resulted in lower water uptake, reduced water vapor permeability and decreasing apparent compound diffusivities. In contrast, the affinity of the investigated drugs and parabens to the films substantially increased upon MAS addition. The obtained new knowledge can be helpful for the development of novel coating materials (based on QPM-MAS blends) for controlled-release dosage forms. PMID:26004005

  2. Quaternary transgressive and regressive depositional sequences in the East China Sea

    Institute of Scientific and Technical Information of China (English)

    LIUZhenxia; YINPing; XIONGYingqian; S.Beme; A.Trentesaux; LIChaoxin

    2003-01-01

    Based on the interpretation more than 4000 km sparker single channel seismic profiles and the comparison with Borehole DZQ4 on the outer shelf of the East China Sea (ECS),the seismic sequences,sedimentary facies and paleo-sedimentary environment are studied to establish the chronology framework and discuss the Quaternary transgressive and regressive sequences of the ECS shelf as well as their response to glacio-eustatic sea-level changes.The sea level of the ECS fluctuated with global climate changes in the Quaternary.During the sea level rise,the pacific tidal wave impacted actively on the ECS continental shelf and the reciprocating tidal currents in NW-SE direction formed tidal sand ridges,which represent large transgressive deposits visible on the seismic profiles.In response to sea level fall,the Yangtze River deltas prograded seaward and built massive subaqueous deltas to form regressive sequences on the seismic profiles.Alternative transgression and regression sequences were vertically distributed on the ECS shelf with the frequent eustacy in the Quaternary.The gentle slope of the ECS shelf makes it possible for the coastline to migrate hundreds of kilometers forth and back on the shelf because of tens of meters sea level changes,in the meanwhile,the Yangtze River discharged large amounts of sediments into the ECS resulting in large-scale subaqueous deltas and tidal sand ridges.There have developed 3 stages of tidal sand ridges and 4 stages of deltas on the ECS shelf since oxygen isotope stage 8.

  3. Enhanced water-solubility, antibacterial activity and biocompatibility upon introducing sulfobetaine and quaternary ammonium to chitosan.

    Science.gov (United States)

    Chen, Yuxiang; Li, Jianna; Li, Qingqing; Shen, Yuanyuan; Ge, Zaochuan; Zhang, Wenwen; Chen, Shiguo

    2016-06-01

    Chitosan (CS) has attracted much attention due to its good antibacterial activity and biocompatibility. However, CS is insoluble in neutral and alkaline aqueous solution, limiting its biomedical application to some extent. To circumvent this drawback, we have synthesized a novel N-quaternary ammonium-O-sulfobetaine-chitosan (Q3BCS) by introducing quaternary ammonium compound (QAC) and sulfobetaine, and its water-solubility, antibacterial activity and biocompatibility were evaluated compare to N-quaternary ammonium chitosan and native CS. The results showed that by introducing QAC, antibacterial activities and water-solubilities increase with degrees of substitution. The largest diameter zone of inhibition (DIZ) was improved from 0 (CS) to 15mm (N-Q3CS). And the water solution became completely transparent from pH 6.5 to pH 11; the maximal waters-solubility was improved from almost 0% (CS) to 113% at pH 7 (N-Q3CS). More importantly, by further introducing sulfobetaine, cell survival rate of Q3BCS increased from 30% (N-Q3CS) to 85% at 2000μg/ml, which is even greater than that of native CS. Furthermore, hemolysis of Q3BCS was dropped sharply from 4.07% (N-Q3CS) to 0.06%, while the water-solution and antibacterial activity were further improved significantly. This work proposes an efficient strategy to prepare CS derivatives with enhanced antibacterial activity, biocompatibility and water-solubility. Additionally, these properties can be finely tailored by changing the feed ratio of CS, glycidyl trimethylammonium chloride and NCO-sulfobetaine. PMID:27083366

  4. Influence of moisture content on shearing strength of unsaturated undisturbed quaternary system middle pleistocene

    Institute of Scientific and Technical Information of China (English)

    钟祖良; 刘元雪; 刘新荣; 李小勇; 王睢

    2015-01-01

    The unsaturated undisturbed quaternary system middle pleistocene loess, a typical unsaturated soil, often occurs in the implementation of western development strategy. To obtain the shearing strength characteristics of this unsaturated undisturbed loess, based on the analysis of mineral composition, the triaxial shear test of undisturbed quaternary system middle pleistocene loess under different moisture contents is conducted with the specialized triaxial instrument for unsaturated soil. The test results show that the mainly mineral composition of undisturbed quaternary system middle pleistocene loess is quartz and albite. Under the same confining pressure, the matric suction increases with the decrease of moisture content. The smaller the moisture content, the larger the matric suction; the higher the moisture content, the lower the matric suction. Under the same moisture content, the matric suction increases with the confining pressure and reaches a maximum when the confining pressure is 100 kPa, and then decreases with the increase of confining pressure. This phenomenon is closely related to the grain contact tightness of soil mass under high confining pressure. According to the triaxial test of loess, the sample of loess experiences 4 stages from loading to failure: 1) compaction stage; 2) compression stage; 3) microcrack developing stage; 4) shear failure stage. The test sample is of brittle failure (weak softening) under low moisture content and confining pressure. With the decrease of matric suction and the increase of consolidated confining pressure, the stress−strain curve changes from softening type to ideal plastic type. In the shearing strength parameters of unsaturated undisturbed loess, the influence of moisture content on internal friction angle is small, but that on cohesive force is obvious. Therefore, the shearing strength of unsaturated undisturbed loess is higher than that of saturated undisturbed loess and varies with the moisture content.

  5. Soil-landscape development and late Quaternary environmental change in coastal Estremadura, Portugal

    Science.gov (United States)

    Daniels, Michael; Haws, Jonathan; Benedetti, Michael; Bicho, Nuno

    2015-04-01

    This poster integrates soil-landscape analysis with archaeological survey and paleoenvironmental reconstruction. Soils in surface and buried contexts in Estremadura, Portugal, provide evidence of landscape stability and instability, relative age relationships between landforms, and general paleoenvironmental conditions during the late Quaternary. These factors provide insight into the distribution and condition of Paleolithic archaeological sites and help understand the record of human settlement in the region. Late Pleistocene and Holocene dunes extend inland approximately 10 km from coastal source regions. Surface soils in Holocene dunes under maritime pine (Pinus pinaster) forest exhibit A, E, C/Bh and A, C horizon sequences and classify as Quartzipsamments. Surface soils in late Pleistocene dunes exhibit A, E, Bh, Bhs, Bs horizon sequences and classify as Haplorthods. Both Pleistocene and Holocene dunes commonly bury a heavily weathered soil formed in calcareous sandstone. The boundary between underlying buried soils and overlying surface soils is characterized by a lag deposit of medium to coarse, moderately-rounded gravels, underlain immediately by subsurface Bt and Bss horizons. The lag deposit and absence of buried A horizons both indicate intense and/or prolonged surface erosion prior to burial by late Quaternary dunes. Soil-geomorphic relationships therefore suggest at least two distinct episodes of dune emplacement and subsequent landscape stability following an extensive episode late Pleistocene landscape instability and soil erosion. A conceptual model of soil-landscape evolution through the late Quaternary and Holocene results from the integration of soil profile data, proxy paleoenvironmental data, and the partial record of human settled as revealed in the archaeological record.

  6. Tectonic control on the Late Quaternary hydrography of the Upper Tiber Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Benvenuti, Marco; Bonini, Marco; Moroni, Adriana

    2016-09-01

    We examine the intramontane Upper Tiber Basin in the Northern Apennines (central Italy), where sub-orthogonal fault systems forced river deviation and the abandonment of alluvial fans since the late Middle Pleistocene. Archaeological material, spanning the Middle Palaeolithic-Iron Age, was collected mostly from the surface of the Late Quaternary alluvial landforms and related deposits (MUP and HOL units). This information contributed to the partial dating of seven major stages of drainage development. Normal faults parallel and transverse to the basin trend were active at different times and conditioned the valley pattern of the Middle (MUP1-2)-Late (MUP3) Pleistocene Tiber, Singerna, Sovara and Tignana rivers, which still flow today into the basin. The MUP1 and the MUP3 fans were beheaded by the displacement of their feeder valleys along the basin-transverse Carmine and Montedoglio faults. In some cases, the former feeder rivers underwent stream piracy but their courses mostly deviated in response of the topographic gradient created by faulting, as well as through the incision of new valleys that exploited the lithological contrast along the fault lines. The MUP3 Tignana fan was abandoned mostly due to the activity of the basin-parallel, dip-slip Sansepolcro fault. Subsidence driven by the basin-parallel Anghiari and Sansepolcro fault systems also provided the accommodation space for the MUP3 and HOl1-2 Afra fans between Late Pleistocene and early-mid Holocene. This study exemplifies the interplay between longitudinal and transverse fault systems, and the Late Quaternary hydrographic evolution of an extensional basin settled in the axial zone of an active fold-and-thrust belt. Although the faulting has interacted with the forcing exerted by the Late Quaternary climate fluctuations on the basin drainage systems, the tectonic rates are sufficiently high to represent the prime controller on base-level change and drainage routing patterns.

  7. Geothermal prospecting by geochemical methods in the Quaternary volcanic province of Dhamar (central Yemen)

    Science.gov (United States)

    Minissale, Angelo; Vaselli, Orlando; Mattash, Mohamed; Montegrossi, Giordano; Tassi, Franco; Ad-Dukhain, Abdulsalam; Kalberkamp, Ulrich; Al-Sabri, Ali; Al-Kohlani, Taha

    2013-01-01

    This paper deals with geothermal prospecting carried out in the Quaternary volcanic field of Dhamar, which is located almost in the centre of the main Oligo-Miocene basaltic trap plateau of Yemen. By applying geochemical and thermometric techniques in domestic wells producing water from the shallow unconfined aquifer in the area, which is prevalently hosted inside the Quaternary volcano-clastic material, a closed thermal anomaly associated with the Quaternary volcanic activity was well delineated. Although the aquifer(s) has a Ca-Na-HCO3 composition, that is typical of shallow groundwater, there are several chemical anomalies in the hotter central area compared to typical aquifers: i) the pH is lower and, consequently, the calculated partial pressure of CO2 in solution is higher, ii) the electrical conductivity is higher, iii) the total salinity is higher and iv) the fluoride ion concentration is higher. Such chemical anomalies in the hotter part of the aquifer do not seem to be generated by the rising and/or mixing of deep hydrothermal components rising into the shallow aquifer, but rather produced by enhanced water-rock interaction processes resulting from the higher temperature of the aquifer and its greater acidity. By applying some speculative calculations, based on the likely temperature of rainfall in the area and the depth and temperature of individual wells, the local thermal gradients in the area have been calculated. The thermal gradient varies from less than the average Earth gradient at the periphery of the delimitated thermal anomaly, to more than 250 °C/km, within an extensive area (exceeding 200 km2) where the gradient is greater than 100/120 °C/km.

  8. Fluvial responses to late Quaternary climate change in the Shiyang River drainage system, western China

    Science.gov (United States)

    Gao, Hongshan; Li, Zongmeng; Pan, Baotian; Liu, Fenliang; Liu, Xiaopeng

    2016-04-01

    As a drainage system located in arid western China, the Shiyang River, combined with considerable fluvial strata and landform information, provides an environmental context within which to investigate fluvial responses to late Quaternary climate change. Sedimentological analysis and optically stimulated luminescence (OSL) dating enabled us to reconstruct the processes and fluvial styles of three sedimentary sequences of the Shagou and Hongshui rivers in the Shiyang drainage system. Our results present a variety of river behaviors during the late Quaternary in these areas. In the upstream Shiyang River, Zhangjiadazhuang (ZJDZ) profile of the Shagou was dominated by aggradation and a meandering channel pattern at 10.6-4.2 ka, while a noticeable channel incision occurred at ~ 4.2 ka followed by lateral channel migration. In the downstream Shiyang River, Datugou (DTG) profile of the Hongshui was an aggrading meandering river from 39.7 to 7.2 ka while channel incision occurred at 7.2 ka. Another downstream profile, Wudunwan (WDW) of the Hongshui was also characterized by aggradation from 22.4 to 4.8 ka; however, its channel pattern shifted from braided to meandering at ~ 13 ka. A discernable downcutting event occurred at ~ 4.8 ka, followed by three channel aggradation and incision episodes prior to 1.8 ka. The last 1.8 ka has been characterized by modern channel and floodplain development. The fluvial processes and styles investigated have a close correlation with late Quaternary climate change in the Shiyang River drainage. During cold phases, the WDW reach was dominated by aggradation with a braided channel pattern. During warm phases, the rivers that we investigated were also characterized by aggradation but with meandering channel patterns. Channel incision events and changes of fluvial style occurred mainly during climate transitions.

  9. Seismic stratigraphy and depositional history of late Quaternary deposits in the Yellow Sea.

    Science.gov (United States)

    Lee, Gwang-Soo; Yoo, Dong Geun; Bae, Sungho; Choul Kim, Dae; Yi, Hi-Il

    2016-04-01

    To identify the seismic stratigraphy and depositional history of late Quaternary deposits in the Yellow Sea, approximately 52,600 line-km of Chirp seismic profiles and 5,060 line-km of Sparker seismic profiles were analyzed. The Yellow Sea are correspond to three sedimentary environments: (1) a various scale sand ridges/waves and mud belt (the western inner-shelf of the Korean Peninsula), (2) recent- and paleo-channels, erosional and broad surface (the center of the Yellow Sea), and (3) prodelta mud patch (the eastern offshore of China). Based on the seismic stratigraphic analysis of seismic profiles, the late Quaternary deposits in the Yellow Sea are divided into five distinctive seismic units (units CY1~5), consisting of two depositional sequences that can be defined as erosional and disconformable strata. Each unit show different seismic facies and geometry, and is clearly separated by each bounding surface. The major depositional processes and sediment dispersal systems during the late Quaternary in the Yellow Sea are: (1) regressive estuarine/deltaic deposits (unit CY1), (2) transgressive incised channel fill (unit CY2), (3) transgressive sand sheet (unit CY3), (4) transgressive sand ridges (unit CY4), and (5) prodelta/recent mud (unit CY5). The depositional sequences follow the general concepts of sequence stratigraphy very well. Lower sequence (DI) correspond to the falling stage systems tract regarded as regressive estuarine or deltaic deposits (unit CY1), whereas upper sequence (DII) consists of a set of the transgressive (units CY2, CY3, and CY4) and highstand systems tract (unit CY5) formed since the last-glacial period.

  10. A“Yellow Cap” on Quaternary Red Clay in Jiujiang,Jiangxi Province

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujing,Jiangxi Province,A typical profile was established.Both particle size distribution and REE(rare earth elements)characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin and close similarity of Nanjing Xiashu Loess.The study also implied aeolian origin of the underlying Quaternary red clay,Compared with the red clay,the yellow-brown-colored earth was less weathered because of its lower content of free iron and higher mole ratios of SiO2/Al2O3 and SiO2(Fe2O3+Al2O3) as well as its less developed chemical microtextures of quartz grains.In order to study the ages of the two deposits comparatively,the thermoluminescent dating method was used.As a result,the bottom of the yellow-brown-colored earth was dated to 60±5 ka B.P.and the upper part of the red clay 388±54 ka B.P.It was suggested that the yellow-brown-colored earth earth was formed in the Late Pleistocene and was probably the aeolian deposit of the Last Glacial,which corresponded with the Malan Loess in the Loess Plateau of the northwestern part of China,while the underlying red clay was formed in the Middle Pleistocene.A“yellow cap” on Quaternary red clay in Jiujiang implied a great climatic and environmental variation in the beginning of the Late Pleistocene in the southern part of China,especially in the middle and lower reaches of the Yangtze River,The event not only halted the rubification,once dominating the region but also produced a widespread covering of aeolian deposit,as only occurred in the cold and dry environment.

  11. Quaternary landscape evolution driven by slab-pull mechanisms in the Granada Basin (Central Betics)

    Science.gov (United States)

    Pérez-Peña, J. V.; Azañón, J. M.; Azor, A.; Booth-Rea, G.; Galve, J. P.; Roldán, F. J.; Mancilla, F.; Giaconia, F.; Morales, J.; Al-Awabdeh, M.

    2015-11-01

    The Granada Basin is one of the largest Neogene-Quaternary intramontane basins of the Betic Cordillera in SE Spain. The landscape evolution in this basin is complex and does not respond to a simple model of headward erosion following river capture of a former endorheic catchment. In the NE border of the basin, the drainage network is highly incised and reveals two different stages of river development since the Pleistocene. The older drainage network presents low incision, being locally controlled by ENE-WSW open folds. The present-day drainage network features deep incised valleys with a well-defined local base-level controlled by NW-SE normal faults. The ENE-WSW open folds were generated by compressional stresses and affect a geomorphic surface that caps the local sedimentary sequence. These folds are thought to reactivate a Pliocene roll-over formed in the hanging wall of ENE-WSW normal faults that bound the Granada Basin to the north and the deepest Pliocene depocenter. On the contrary, Quaternary depocenters are located in the hanging wall of the NW-SE-oriented normal faults that control the present-day drainage network (NW-SE oriented). The activity of these faults also contributes to the erosion of the Pliocene depocenter located to the north, thus suggesting a southwestward migration of the loci of extension to the center of the basin. The broad-scale scenario envisaged to explain the Pliocene-Quaternary evolution of the NE border of the Granada Basin is one dominated by mantle slab-pull coeval with the Africa-Iberia continuous convergence.

  12. Beyond BLASTing: tertiary and quaternary structure analysis helps identify major vault proteins.

    Science.gov (United States)

    Daly, Toni K; Sutherland-Smith, Andrew J; Penny, David

    2013-01-01

    We examine the advantages of going beyond sequence similarity and use both protein three-dimensional (3D) structure prediction and then quaternary structure (docking) of inferred 3D structures to help evaluate whether comparable sequences can fold into homologous structures with sufficient lateral associations for quaternary structure formation. Our test case is the major vault protein (MVP) that oligomerizes in multiple copies to form barrel-like vault particles and is relatively widespread among eukaryotes. We used the iterative threading assembly refinement server (I-TASSER) to predict whether putative MVP sequences identified by BLASTp and PSI Basic Local Alignment Search Tool are structurally similar to the experimentally determined rodent MVP tertiary structures. Then two identical predicted quaternary structures from I-TASSER are analyzed by RosettaDock to test whether a pair-wise association occurs, and hence whether the oligomeric vault complex is likely to form for a given MVP sequence. Positive controls for the method are the experimentally determined rat (Rattus norvegicus) vault X-ray crystal structure and the purple sea urchin (Strongylocentrotus purpuratus) MVP sequence that forms experimentally observed vaults. These and two kinetoplast MVP structural homologs were predicted with high confidence value, and RosettaDock predicted that these MVP sequences would dock laterally and therefore could form oligomeric vaults. As the negative control, I-TASSER did not predict an MVP-like structure from a randomized rat MVP sequence, even when constrained to the rat MVP crystal structure (PDB:2ZUO), thus further validating the method. The protocol identified six putative homologous MVP sequences in the heterobolosean Naegleria gruberi within the excavate kingdom. Two of these sequences are predicted to be structurally similar to rat MVP, despite being in excess of 300 residues shorter. The method can be used generally to help test predictions of homology via

  13. Late Quaternary lake-level changes of Lake El'gygytgyn, NE Siberia

    OpenAIRE

    Juschus, O.; Pavlov, M.; G. Schwamborn; Preusser, F.; Fedorov, G.; Melles, M.

    2011-01-01

    Lake El'gygytgyn is situated in a 3.6 Ma old impact crater in northeastern Siberia. Presented here is a reconstruction of the Quaternary lake-level history as derived from sediment cores from the southern lake shelf. There, a cliff-like bench 10 m below the modern water level has been investigated. Deep-water sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene period. One period with low lake level prior to Marine Oxygen Isotope Stage (MIS) 3 has been identified, fo...

  14. Quaternary volcanism, tectonics, and sedimentation in the Idaho National Engineering Laboratory area

    Energy Technology Data Exchange (ETDEWEB)

    Hackett, W.R.; Smith, R.P.

    1992-01-01

    In this article, we discuss the regional context and describe localities for a two-day field excursion in the vicinity of the Idaho National Engineering Laboratory (INEL). We address several geologic themes: (1) Late Cenozoic, bimodal volcanism of the Eastern Snake River Plain (ESRP), (2) the regional tectonics and structural geology of the Basin and Range province to the northwest of the ESRP, (3) fluvial, lacustrine, and aeolian sedimentation in the INEL area, and (4) the influence of Quaternary volcanism and tectonics on sedimentation near the INEL.

  15. Quaternary volcanism, tectonics, and sedimentation in the Idaho National Engineering Laboratory area

    Energy Technology Data Exchange (ETDEWEB)

    Hackett, W.R.; Smith, R.P.

    1992-09-01

    In this article, we discuss the regional context and describe localities for a two-day field excursion in the vicinity of the Idaho National Engineering Laboratory (INEL). We address several geologic themes: (1) Late Cenozoic, bimodal volcanism of the Eastern Snake River Plain (ESRP), (2) the regional tectonics and structural geology of the Basin and Range province to the northwest of the ESRP, (3) fluvial, lacustrine, and aeolian sedimentation in the INEL area, and (4) the influence of Quaternary volcanism and tectonics on sedimentation near the INEL.

  16. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

    OpenAIRE

    Tibaldi, A.; Università degli Studi di Milano-Bicocca; Corazzato, C.; Università degli Studi di Milano-Bicocca; Rovida, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia

    2008-01-01

    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognised four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. Th...

  17. Late-Quaternary exhumation rates constrained by OSL thermochronometry at the Franz Josef Glacier, New Zealand

    Science.gov (United States)

    Duverger, Arnaud; King, Georgina; Valla, Pierre; Cox, Simon; Herman, Frederic

    2016-04-01

    The Southern Alps of New Zealand are often cited as the primary example of a mountain range that has reached exhumation and topographic steady state, especially on the West Coast where exhumation rates reach up to about 10 mm/yr. However, cyclic climatic changes, throughout the Quaternary period have meant that the Alps cycled between being completely glaciated and ice free. The impact that such glacial cycles may have had on the spatial variability of erosion rates remains poorly constrained. Here we use Optically Stimulated Luminescence (OSL) as a very low temperature thermochronometer to constrain rock cooling histories at 10-100 kyr timescales on samples collected near the Franz Josef glacier. OSL-thermochronometry is based on the amount of electrons accumulated in the lattice defects of natural minerals such as quartz or feldspar, due to the competing effects of charge trapping due to the natural radioactivity within the rock and charge detrapping due to thermal loss during rock exhumation towards the surface. We collected 9 samples along the Waiho valley (crossing the Alpine Fault) and the Franz Josef glacier to quantify late-Quaternary exhumation rates and their potential spatial variations. Bedrock samples have been crushed to extract the light-safe rock interiors which have then been processed to isolate potassium-rich feldspars (K-feldspars). We used the Infra-Red Stimulated Luminescence at 50°C (IRSL50) protocol, including the measurement of the natural IRSL50 trapped charge population and the laboratory characterization of sample-specific thermal and athermal kinetic parameters. Once measured, the luminescence signal can be inverted into cooling histories. We also explored the potential of the recently developed multi-OSL-thermochronometer (King et al., accepted) to better constrain the cooling path. Our first OSL measurements show that samples are not in saturation and thus contain useful thermochronometric information over the last ~100 kyr. Inverse

  18. Dimethyl carbonate synthesis via transesterification catalyzed by quaternary ammonium salt functionalized chitosan

    Institute of Scientific and Technical Information of China (English)

    Yuan Zhao; Liang Nian He; Yuan Yi Zhuang; Jin Quan Wang

    2008-01-01

    A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate (DMC) synthesis by the transesterification of propylene carbonate (PC) with methanol. The effects of various reaction variables like reaction time, temperature and pressure on the catalytic performance were also investigated. 54% DMC yield and 71% PC conversion were obtained under the optimal reaction conditions. Notably, the catalyst was able to be reused with retention of high catalytic activity and selectivity. Consequently, the process presented here has great potential for industrial application due to its advantages such as stability, easy preparation from renewable biopolymer, and simple separation from products.

  19. Oceanography and Quaternary geology of the St. Lawrence Estuary and the Saguenay Fjord

    International Nuclear Information System (INIS)

    The St. Lawrence Estuary is an environment marked by important freshwater discharge and well stratified water masses, recording large seasonal contrast in surface waters from freezing conditions in winter to temperate conditions in summer due to a very strong seasonal cycle in overlying air temperature. High productivity takes place in the pelagic and benthic environments, where a recent trend toward bottom water hypoxia is observed. The area was profoundly marked by the Quaternary glaciations. Thick glaciomarine sequences dating from the last deglaciation are observed in the Estuary and along the shores, whereas a relatively thin layer (a few meters at most) of hemipelagic mud was deposited during the Holocene.

  20. Synthesis, Spectroscopic and Theoretical Studies of New Dimeric Quaternary Alkylammonium Conjugates of Sterols

    Directory of Open Access Journals (Sweden)

    Bogumił Brycki

    2014-07-01

    Full Text Available New dimeric quaternary alkylammonium conjugates of sterols were obtained by two step reactions of ergosterol, cholesterol and cholestanol with bromoacetic acid bromide, followed by bimolecular nucleophilic substitution with N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'',N''-pentamethyldiethylenetriamine and 3,3'-iminobis- (N,N-dimethylpropylamine. The product structures were confirmed by spectral (1H-NMR, 13C-NMR, FT-IR analysis, mass spectrometry (ESI-MS and PM5 semiempirical methods. Additionally in silico studies have been conducted for the synthesized compounds on the basis of Prediction of Activity Spectra for Substances (PASS.

  1. Synthesis, Spectroscopic and Theoretical Studies of New Dimeric Quaternary Alkylammonium Conjugates of Sterols

    OpenAIRE

    Bogumił Brycki; Hanna Koenig; Iwona Kowalczyk; Tomasz Pospieszny

    2014-01-01

    New dimeric quaternary alkylammonium conjugates of sterols were obtained by two step reactions of ergosterol, cholesterol and cholestanol with bromoacetic acid bromide, followed by bimolecular nucleophilic substitution with N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'',N''-pentamethyldiethylenetriamine and 3,3'-iminobis- (N,N-dimethylpropylamine). The product structures were confirmed by spectral (1H-NMR, 13C-NMR, FT-IR) analysis, mass spectrometry (ESI-MS) and PM5 semiempirical method...

  2. Hydrographic changes in the Agulhas Recirculation Region during the late Quaternary.

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, Dinesh K.; Saraswat, R.; Khare, N.; Pandey, A.C.; Nigam, R.

    –758, 2014 www.clim-past.net/10/745/2014/ doi:10.5194/cp-10-745-2014 © Author(s) 2014. CC Attribution 3.0 License. Climate of the Past O pen A ccess Hydrographic changes in the Agulhas Recirculation Region during the late Quaternary D. K. Naik1, R. Saraswat1..., 1993; Lutjeharms and Ansorge 2001; Quartly et al., 2006). The retroflection depends on the in- ertia of the AC off Africa, wind stress over this region and the bottom topography (Lutjeharms and Ballegooyen, 1988; Le Bars et al., 2012). A distinct...

  3. Quaternary Oxide of Cerium, Terbium, Praseodymium and Zirconium for Three-Way Catalysts

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Oxygen storagecapacity (OSC), oxygen buffer capacity (OBC), X-ray diffraction and electron diffraction pattern, high resolution electron microscopy were used to study the quaternary oxides, i.e., of Ce, Tb, Pr and Zr. (Ce0.6Tb0.2Zr0.2O2-δ and Ce0.6Pr0.2Zr0.2O2-δ). OSC and OBC data indicate that these oxides have very good oxygen transfer capacity (OTC) and their pseudo-solid solutions exhibit fluorite-type structure. These oxides may act as a good candidate for three-way catalysts (TWC).

  4. Bandgap tunable colloidal Cu-based ternary and quaternary chalcogenide nanosheets via partial cation exchange

    Science.gov (United States)

    Ramasamy, Parthiban; Kim, Miri; Ra, Hyun-Soo; Kim, Jinkwon; Lee, Jong-Soo

    2016-04-01

    Copper based ternary and quaternary semiconductor nanostructures are of great interest for the fabrication of low cost photovoltaics. Although well-developed syntheses are available for zero dimensional (0D) nanoparticles, colloidal synthesis of two dimensional (2D) nanosheets remains a big challenge. Here we report, for the first time, a simple and reproducible cation exchange approach for 2D colloidal Cu2GeSe3, Cu2ZnGeSe4 and their alloyed Cu2GeSxSe3-x, Cu2ZnGeSxSe4-x nanosheets using pre-synthesized Cu2xSe nanosheets as a template. A mechanism for the formation of Cu2-xSe nanosheets has been studied in detail. In situ oxidation of Cu+ ions to form a CuSe secondary phase facilitates the formation of Cu2-xSe NSs. The obtained ternary and quaternary nanosheets have average lateral size in micrometers and thickness less than 5 nm. This method is general and can be extended to produce other important ternary semiconductor nanosheets such as CuIn1-xGaxSe2. The optical band gap of these nanosheets is tuned from 1 to 1.48 eV, depending on their composition.Copper based ternary and quaternary semiconductor nanostructures are of great interest for the fabrication of low cost photovoltaics. Although well-developed syntheses are available for zero dimensional (0D) nanoparticles, colloidal synthesis of two dimensional (2D) nanosheets remains a big challenge. Here we report, for the first time, a simple and reproducible cation exchange approach for 2D colloidal Cu2GeSe3, Cu2ZnGeSe4 and their alloyed Cu2GeSxSe3-x, Cu2ZnGeSxSe4-x nanosheets using pre-synthesized Cu2xSe nanosheets as a template. A mechanism for the formation of Cu2-xSe nanosheets has been studied in detail. In situ oxidation of Cu+ ions to form a CuSe secondary phase facilitates the formation of Cu2-xSe NSs. The obtained ternary and quaternary nanosheets have average lateral size in micrometers and thickness less than 5 nm. This method is general and can be extended to produce other important ternary

  5. Quaternary Barrier InGaAs/AlInGaAs Terahertz Quantum Cascade Laser

    International Nuclear Information System (INIS)

    Full text: We report on properties of a quaternary barrier InGaAs/AlInGaAs terahertz quantum cascade laser grown on Fe doped InP substrate. The active layer was designed using a scheme based on bound-to-continuum four quantum wells. Al composition of 17% in the AlInGaAs barriers was used. Ridge laser devices with double metal Au-Au waveguide emitted at 3.4 THz with a threshold current density of 590 A/cm2 at 10 K. The maximum operation temperature was 130 K. (author)

  6. Growth and Properties of Quaternary Alloy Magnetic Semiconductor (InGaMn)As

    OpenAIRE

    Ohya, Shinobu; Shimizu, Hiromasa; Higo, Yutaka; Sun, Jiaming; Tanaka, Masaaki

    2001-01-01

    We have studied growth and properties of quaternary alloy magnetic semiconductor (InGaMn)As grown both on GaAs substrates and on InP substrates by low-temperature molecular-beam epitaxy (LT-MBE). (InGaMn)As thin films were ferromagnetic below ~30 K, exhibiting strong magneto-optical effect. The lattice constant of [(InyGa1-y)1-xMnx]As, whose Mn concentration x is below 4%, is slightly smaller than that of InyGa1-yAs with the same In/Ga content ratio. We have also obtained very smooth surface ...

  7. Gravity field separation and mapping of buried quaternary valleys in Lolland, Denmark using old geophysical data

    DEFF Research Database (Denmark)

    Møller, M.J.; Olsen, Henrik; Ploug, C.;

    2007-01-01

    In this paper we utilise the old industrial data for planning new surveys. The overall purpose is a detailed mapping of possible aquifers for the island of Lolland, Denmark. This is done through detection and modelling of the buried quaternary valleys, which either can serve as potential aquifers...... or potential aquifer barriers. The present paper deals only with one aspect of a larger study; namely a case story leading to the detection of unknown buried valleys and the first attempts to model them in 3D from gravity and seismics. Also, the emphasis here is not on any theoretical or even...

  8. Oceanography and Quaternary geology of the St. Lawrence Estuary and the Saguenay Fjord

    Energy Technology Data Exchange (ETDEWEB)

    De Vernal, Anne [GEOTOP, Universite du Quebec a Montreal, PO Box 8888, succursale ' centre ville' Montreal, QC, H3C 3P8 (Canada); St-Onge, Guillaume [GEOTOP and Institut des Sciences de la Mer (ISMER), Universite du Quebec a Rimouski, 310, Allee des Ursulines, Rimouski, QC, G5L 3A1 (Canada); Gilbert, Denis, E-mail: devernal.anne@uqam.ca [Institut Maurice-Lamontagne, Peches et Oceans Canada, 850 route de la Mer, CP 1000 Mont-Joli, QC, G5H 3Z4 (Canada)

    2011-05-15

    The St. Lawrence Estuary is an environment marked by important freshwater discharge and well stratified water masses, recording large seasonal contrast in surface waters from freezing conditions in winter to temperate conditions in summer due to a very strong seasonal cycle in overlying air temperature. High productivity takes place in the pelagic and benthic environments, where a recent trend toward bottom water hypoxia is observed. The area was profoundly marked by the Quaternary glaciations. Thick glaciomarine sequences dating from the last deglaciation are observed in the Estuary and along the shores, whereas a relatively thin layer (a few meters at most) of hemipelagic mud was deposited during the Holocene.

  9. Bio- and aminostratigraphy of some Quaternary marine deposits in West Greenland

    DEFF Research Database (Denmark)

    Funder, Svend Visby; Simonarson, Leifur A.

    1984-01-01

    fauna from Mudderbugt is reworked, but the presence of Chlamys islandica indicates that conditions were not entirely different from the present. Amino-acid analyses on shells from the three sites place them in three distinct aminozones, with Patorfik as the oldest and Laksebugt the youngest. Age...... estimates using this and geological and biological evidence suggest that the Laksebugt aminozone dates from the isotopic stage 5-6 transition (130 ka). The Patorfik aminozone is probably of mid- or early Quaternary age (235-1800 ka). Correlation with the few previously known pre-Holocene marine deposits of...

  10. Late Quaternary changes in depositional processes along the western margin of the Indus Fan

    Digital Repository Service at National Institute of Oceanography (India)

    Govil, P.; Naidu, P.D.

    stream_size 22748 stream_content_type text/plain stream_name Geo-Mar. Lett_28_1.pdf.txt stream_source_info Geo-Mar. Lett_28_1.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 ORIGINAL Late Quaternary... was separated on the basis of Stokes’ Law of settling. The separated clay aliquots were treated with 5 ml acetic acid and 10 ml hydrogen peroxide to remove carbonate and organic matter respectively. The aliquots were then washed several times with de...

  11. Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

    Directory of Open Access Journals (Sweden)

    Elizabeth P. Jones

    2011-11-01

    Full Text Available A method was developed for the synthesis of α-alkyl, α-aryl-bislactim ethers in good to excellent yields and high diastereoselectivities, consisting of a facile one-pot procedure in which the aryl group is introduced by means of a nucleophilic addition to benzyne and the alkyl group by alkylation of a resultant benzylic anion. Hydrolysis of the sterically less hindered adducts gave the corresponding quaternary amino acids with no racemization, whereas hydrolytic ring opening gave the corresponding valine dipeptides from bulkier bislactims.

  12. Late quaternary insects of Rancho La Brea and McKittrick, California

    Science.gov (United States)

    Miller, Scott E.

    1983-07-01

    Asphalt-impregnated sediments at Rancho La Brea (Los Angeles County) and McKittrick (Kern County) in California provide a rich Quaternary insect record. Ages of various sites at Rancho La Brea range from more than 40,000 14C yr B.P. to modern. McKittrick insects studied by W. D. Pierce are not contemporaneous with the late Pleistocene vertebrate fauna, but are only about 7000 14C yr old. The major paleoecological groupings are: (1) ground dwellers, (2) aquatics. (3) scavengers, and (4) miscellaneous. Contrary to conclusions of earlier authors, most specimens represent modern species. Only two apparent terminal Pleistocene extinctions are recognized. both dung beetles (Scarabaeidae).

  13. Interionic pair potentials and partial structure factors of compound-forming quaternary NaSn liquid alloy: First principle approach

    Indian Academy of Sciences (India)

    Anil Thakur; P K Ahluwalia

    2007-10-01

    In this paper formulae for partial structure factors have been used to study partial structure factors of compound-forming quaternary liquid alloys by considering Hoshino's m-component hard-sphere mixture, which is based on Percus-Yevic equation of Hiroike. Formulae are applied to NaSn (Na, Sn, NaSn, Na3Sn) which is considered as a quaternary liquid mixture with the formation of two compounds simultaneously. We have compared the total structure factors for ternary and quaternary alloys with experimental total structure factors which are found to be in good agreement. This suggests that, for suitable stoichiometric composition, two compounds are formed simultaneously. The hard-sphere diameters needed have been calculated using Troullier and Martins ab-initio pseudopotentials.

  14. Role of quaternary additions on dislocated martensite, retain austenite and mechanical properties of Fe/Cr/C structural steels

    International Nuclear Information System (INIS)

    The influence of quaternary alloy additions of Mn and Ni to Fe/Cr/C steels which have been designed to provide superior mechanical properties has been investigated. Transmission electron microscopy and x-ray analysis revealed increasing amounts of retained austenite with Mn up to 2 w/o and with 5 w/o Ni additions after quenching from 11000C. This is accompanied by a corresponding improvement in toughness properties of the quaternary alloys. In addition, the generally attractive combinations of strength and toughness in these quaternary alloys is attributed to the production of dislocated lath martensite from a homogeneous austenite phase free from undissolved alloy carbides. Grain-refining resulted in a further increase in the amount of retained austenite

  15. Role of quaternary additions on dislocated martensite, retain austenite and mechanical properties of Fe/Cr/C structural steels

    Energy Technology Data Exchange (ETDEWEB)

    Rao, B.V.N.

    1978-02-01

    The influence of quaternary alloy additions of Mn and Ni to Fe/Cr/C steels which have been designed to provide superior mechanical properties has been investigated. Transmission electron microscopy and x-ray analysis revealed increasing amounts of retained austenite with Mn up to 2 w/o and with 5 w/o Ni additions after quenching from 1100/sup 0/C. This is accompanied by a corresponding improvement in toughness properties of the quaternary alloys. In addition, the generally attractive combinations of strength and toughness in these quaternary alloys is attributed to the production of dislocated lath martensite from a homogeneous austenite phase free from undissolved alloy carbides. Grain-refining resulted in a further increase in the amount of retained austenite.

  16. A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

    Science.gov (United States)

    Mumbaraddi, Dundappa; Sarkar, Sumanta; Peter, Sebastian C.

    2016-04-01

    This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compounds with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications.

  17. Anti-herpesviral effects of a novel broad range anti-microbial quaternary ammonium silane, K21.

    Science.gov (United States)

    Gulve, Nitish; Kimmerling, Kirk; Johnston, Allen D; Krueger, Gerhard R; Ablashi, Dharam V; Prusty, Bhupesh K

    2016-07-01

    We have created a novel quaternary ammonium silane, K21 through sol-gel chemistry, using an ethoxylated version of an organosilane quaternary ammonium compound and TetraEthyl Ortho Silicate (TEOS) as precursors. Previous studies using the precursor molecule quaternary ammonium compounds (QACs) and a methacryloxy version of K21, primarily designed for use in dental healthcare, have shown inhibited growth properties against several types of gram-positive and gram-negative bacteria including Escherichia coli, Streptococcus mutans, Actinomyces naeslundii and Candida albicans etc. Here we tested the effect of K21 on HSV-1, HHV-6A and HHV-7 in in vitro cell culture infection models. Our results show growth inhibitory effect of K21 on HSV-1, HHV-6A and HHV-7 infection. PMID:27181377

  18. Nickel-catalyzed enantioselective hydrovinylation of silyl-protected allylic alcohols:An efficient access to homoallylic alcohols with a chiral quaternary center

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Asymmetric hydrovinylation of silyl-protected allylic alcohols catalyzed by nickel complexes of chiral spiro phosphoramidite ligands was developed.A series of homoallylic alcohols with a chiral quaternary center were produced in high yields(up to 97%) and high enantioselectivities(up to 95% ee).The reaction provides an efficient method for preparing bifunctional compounds with a chiral quaternary carbon center.

  19. Potential of dinoflagellate cyst records for Quaternary climate studies in the New Zealand region

    International Nuclear Information System (INIS)

    This report summarises the results of a pilot study aimed at investigating the potential of using dinoflagellate cyst (dinocyst) records in the New Zealand region for contributing to high-resolution Quaternary climate studies. Dinocyst assemblages were recorded through a rapid interval of climate change, from glacial Marine Isotope Stage (MIS) 6 to interglacial MIS 5 (∼ 160 to 80 kyr), in ODP Site 1123, offshore eastern New Zealand. Twenty-one samples were examined and dinocyst assemblages, along with other palynomorphs such as spores and pollen, were generally well preserved, abundant and diverse. The relative and absolute abundance of dinocysts is highest in MIS 6, with Brigantedinium spp. and Nematosphaeropsis labyrinthus being the dominant taxa. Moreover, the higher concentration of peridinioid and total dinocysts during the glacial suggests that, in comparison with MIS 5, increased nutrient availability in surface waters was present in MIS 6. Other dinocysts that show an affinity with cool oceanic conditions include Impagidinium pallidum and Selenopemphix Antarctica, while Impagidinium paradoxum, I. patulum, I. plicatum, I. strialatum, I. variaseptum and Spiniferites mirabilis are more common during the interglacial MIS 5. Land-derived spore and pollen microfossils are abundant in Site 1123 and notable peaks in absolute abundance are recorded during MIS 5, with two of the peaks being approximately coeval with the warmer phases of Substage 5e and 5a. This pilot study highlights the increasing potential for marine palynology to contribute to Quaternary paleoclimate research in the New Zealand region. (author). 45 refs., 10 figs

  20. Historical distribution of Sundaland’s Dipterocarp rainforests at Quaternary glacial maxima

    Science.gov (United States)

    Cannon, Charles H.; Hijmans, Robert J.; Piessens, Thomas; Saw, Leng Guan; van Welzen, Peter C.; Slik, J. W. Ferry

    2014-01-01

    The extent of Dipterocarp rainforests on the emergent Sundaland landmass in Southeast Asia during Quaternary glaciations remains a key question. A better understanding of the biogeographic history of Sundaland could help explain current patterns of biodiversity and support the development of effective forest conservation strategies. Dipterocarpaceae trees dominate the rainforests of Sundaland, and their distributions serve as a proxy for rainforest extent. We used species distribution models (SDMs) of 317 Dipterocarp species to estimate the geographic extent of appropriate climatic conditions for rainforest on Sundaland at the last glacial maximum (LGM). The SDMs suggest that the climate of central Sundaland at the LGM was suitable to sustain Dipterocarp rainforest, and that the presence of a previously suggested transequatorial savannah corridor at that time is unlikely. Our findings are supported by palynologic evidence, dynamic vegetation models, extant mammal and termite communities, vascular plant fatty acid stable isotopic compositions, and stable carbon isotopic compositions of cave guano profiles. Although Dipterocarp species richness was generally lower at the LGM, areas of high species richness were mostly found off the current islands and on the emergent Sunda Shelf, indicating substantial species migration and mixing during the transitions between the Quaternary glacial maxima and warm periods such as the present. PMID:25385612

  1. Surface Induced Dissociation Yields Quaternary Substructure of Refractory Noncovalent Phosphorylase B and Glutamate Dehydrogenase Complexes

    Science.gov (United States)

    Ma, Xin; Zhou, Mowei; Wysocki, Vicki H.

    2014-03-01

    Ion mobility (IM) and tandem mass spectrometry (MS/MS) coupled with native MS are useful for studying noncovalent protein complexes. Collision induced dissociation (CID) is the most common MS/MS dissociation method. However, some protein complexes, including glycogen phosphorylase B kinase (PHB) and L-glutamate dehydrogenase (GDH) examined in this study, are resistant to dissociation by CID at the maximum collision energy available in the instrument. Surface induced dissociation (SID) was applied to dissociate the two refractory protein complexes. Different charge state precursor ions of the two complexes were examined by CID and SID. The PHB dimer was successfully dissociated to monomers and the GDH hexamer formed trimeric subcomplexes that are informative of its quaternary structure. The unfolding of the precursor and the percentages of the distinct products suggest that the dissociation pathways vary for different charge states. The precursors at lower charge states (+21 for PHB dimer and +27 for GDH hexamer) produce a higher percentage of folded fragments and dissociate more symmetrically than the precusors at higher charge states (+29 for PHB dimer and +39 for GDH hexamer). The precursors at lower charge state may be more native-like than the higher charge state because a higher percentage of folded fragments and a lower percentage of highly charged unfolded fragments are detected. The combination of SID and charge reduction is shown to be a powerful tool for quaternary structure analysis of refractory noncovalent protein complexes, as illustrated by the data for PHB dimer and GDH hexamer.

  2. Radiocarbon ages of upper quaternary deposit in central Nepal and their geomorphological significance

    International Nuclear Information System (INIS)

    The author visited Nepal from October, 1980, to February, 1981, investigated the geomorphology and upper Quaternary geology in Central Nepal, and collected a number of samples for radiocarbon dating. After returning to his university, he dated ten samples by himself. In Nepal, radiocarbon age has been scarcely reported as yet, besides in Kathmandu valley. Therefore, the author's ten data of the age are very important for the late Quaternary chronological study of Nepal Himalayas. In this paper, the author describes sampling localities and horizons, dating results and their geomorphological significance. These ten samples included Pokhara valley, Marsyandi Kohla, Modi Khola, Madi Khola and Muktinath samples. Some conclusion was derived as for the geomorphological development in central Nepal: The last Himalayan glacial age had already ended before 9,000 yr BP (years before A.D. 1950); In the Midland region, from 4,300 to 600 yr BP, some large-scale mudflows broke out nearly contemporaneously in the upper valleys, and they flowed down torrentially and catastrophically to deposit in the middle course of rivers. But the cause of vast quantity of material suddenly brought down from the Great Himalayas has been still left unexplained. The conclusion like this also was able to be applied to the middle Marsyandi Khola and the Pokhara valley. The wide-spread schema that the river was aggraded in the glacial age and degraded in the interglacial age may not be applicable to the rivers in the Midland region of Nepal Himalayas. (Wakatsuki, Y.)

  3. Theoretical studies on CO2 capture behavior of quaternary ammonium-based polymeric ionic liquids.

    Science.gov (United States)

    Wang, Tao; Ge, Kun; Chen, Kexian; Hou, Chenglong; Fang, Mengxiang

    2016-05-14

    Quaternary ammonium-based polymeric ionic liquids (PILs) are novel CO2 sorbents as they have high capacity, high stability and high binding energy. Moreover, the binding energy of ionic pairs to CO2 is tunable by changing the hydration state so that the sorbent can be regenerated through humidity adjustment. In this study, theoretical calculations were conducted to reveal the mechanism of the humidity swing CO2 adsorption, based on model compounds of quaternary ammonium cation and carbonate anions. The electrostatic potential map demonstrates the anion, rather than the cation, is chemically preferential for CO2 adsorption. Further, the proton transfer process from water to carbonate at the sorbent interface is successfully depicted with an intermediate which has a higher energy state. By determining the CO2 adsorption energy and activation energy at different hydration states, it is discovered that water could promote CO2 adsorption by reducing the energy barrier of proton transfer. The adsorption/desorption equilibrium would shift to desorption by adding water, which constitutes the theoretical basis for humidity swing. By analyzing the hydrogen bonding and structure of the water molecules, it is interesting to find that the CO2 adsorption weakens the hydrophilicity of the sorbent and results in release of water. The requirement of latent heat for the phase change of water could significantly reduce the heat of adsorption. The special "self-cooling" effect during gas adsorption can lower the temperature of the sorbent and benefit the adsorption isotherms. PMID:27115032

  4. Landscape evolution of the Ulan Buh Desert in northern China during the late Quaternary

    Science.gov (United States)

    Chen, Fahu; Li, Guoqiang; Zhao, Hui; Jin, Ming; Chen, Xuemei; Fan, Yuxin; Liu, Xiaokang; Wu, Duo; Madsen, David

    2014-05-01

    The evolution of arid environments in northern China was a major environmental change during the Quaternary. Here we present the dating and environmental proxy results from a 35 m long core (A-WL10ZK-1) collected from the Ulan Buh Desert (UBD), along with supplemental data from four other cores. The UBD is one of the main desert dune fields in China and our results indicate the UBD has undergone complex evolution during the late Quaternary. Most of the present UBD was covered by a Jilantai-Hetao Mega-paleolake lasting until ~ 90 ka ago. A sandy desert environment prevailed throughout the UBD during the last glacial period and early Holocene. A wetland environment characterized by the formation of numerous interdunal ponds in the northern UBD occurred at ~ 8-7 ka, although a dune field persisted in the southern UBD. The modern UBD landscape formed after these wetlands dried up. During the last 2000 years, eolian sand from the Badain Jaran Desert has invaded the northern UBD, while farming and overgrazing resulted in the formation of the eastern UBD. We suggest that the formation of UBD landforms is related to the disintegration of the megalake Jilantai-Hetao and to summer monsoon changes during the last glaciation and Holocene.

  5. In Vitro Activity of Quaternary Ammonium Surfactants against Streptococcal, Chlamydial, and Gonococcal Infective Agents.

    Science.gov (United States)

    Inácio, Ângela S; Nunes, Alexandra; Milho, Catarina; Mota, Luís Jaime; Borrego, Maria J; Gomes, João P; Vaz, Winchil L C; Vieira, Otília V

    2016-06-01

    Quaternary ammonium compounds (QAC) are widely used, cheap, and chemically stable disinfectants and topical antiseptics with wide-spectrum antimicrobial activities. Within this group of compounds, we recently showed that there are significant differences between the pharmacodynamics of n-alkyl quaternary ammonium surfactants (QAS) with a short (C12) alkyl chain when in vitro toxicities toward bacterial and mammalian epithelial cells are compared. These differences result in an attractive therapeutic window that justifies studying short-chain QAS as prophylactics for sexually transmitted infections (STI) and perinatal vertically transmitted urogenital infections (UGI). We have evaluated the antimicrobial activities of short-chain (C12) n-alkyl QAS against several STI and UGI pathogens as well as against commensal Lactobacillus species. Inhibition of infection of HeLa cells by Neisseria gonorrhoeae and Chlamydia trachomatis was studied at concentrations that were not toxic to the HeLa cells. We show that the pathogenic bacteria are much more susceptible to QAS toxic effects than the commensal vaginal flora and that QAS significantly attenuate the infectivity of N. gonorrhoeae and C. trachomatis without affecting the viability of epithelial cells of the vaginal mucosa. N-Dodecylpyridinium bromide (C12PB) was found to be the most effective QAS. Our results strongly suggest that short-chain (C12) n-alkyl pyridinium bromides and structurally similar compounds are promising microbicide candidates for topical application in the prophylaxis of STI and perinatal vertical transmission of UGI. PMID:26976875

  6. Optimum quaternary galois field circuit design through carbon nano tube technology

    International Nuclear Information System (INIS)

    Full text: The geometry dependant threshold voltage of carbon nanotube FETs (CNFETs) , has been often used to design a ternary logic family. However , for the last couple of decades , multiple-valued logic (MVL) such as ternary (base=3) or quaternary (base=4) logic styles has attracted considerable attention. MVL circuits can reduce the number of operations necessary to implement a particular mathematical function and further , have an advantage in terms of reduced area. As we progress into an era of nanotechnology , molecular devices are becoming promising alternatives to the existing silicon technology. Carbon nanotube field effect transistors (CNFETs) are being extensively studied as possible successors to Silicon MOSFETs. Research has started in the earnest to understand the device physics of CNFETs as well as to explore possible circuit applications. Implementable CNTFET circuits have operational characteristics to approach the advantage of using MVL in voltage mode. In this paper through using of CNTFET characteristics , we presented new CNTFET circuit design to implement optimum Quaternary Galois Field logic. (authors)

  7. Aqueous two-phase system based on natural quaternary ammonium compounds for the extraction of proteins.

    Science.gov (United States)

    Zeng, Chao-Xi; Xin, Rui-Pu; Qi, Sui-Jian; Yang, Bo; Wang, Yong-Hua

    2016-02-01

    Aqueous two-phase systems, based on the use of natural quaternary ammonium compounds, were developed to establish a benign biotechnological route for efficient protein separation. In this study, aqueous two-phase systems of two natural resources betaine and choline with polyethyleneglycol (PEG400/600) or inorganic salts (K2 HPO4 /K3 PO4 ) were formed. It was shown that in the K2 HPO4 -containing aqueous two-phase system, hydrophobic interactions were an important driving force of protein partitioning, while protein size played a vital role in aqueous two-phase systems that contained polyethylene glycol. An extraction efficiency of more than 90% for bovine serum albumin in the betaine/K2 HPO4 aqueous two-phase system can be obtained, and this betaine-based aqueous two-phase system provided a gentle and stable environment for the protein. In addition, after investigation of the cluster phenomenon in the betaine/K2 HPO4 aqueous two-phase systems, it was suggested that this phenomenon also played a significant role for protein extraction in this system. The development of aqueous two-phase systems based on natural quaternary ammonium compounds not only provided an effective and greener method of aqueous two-phase system to meet the requirements of green chemistry but also may help to solve the mystery of the compartmentalization of biomolecules in cells. PMID:26447826

  8. Cationic curdlan: Synthesis, characterization and application of quaternary ammonium salts of curdlan.

    Science.gov (United States)

    Suflet, Dana M; Popescu, Irina; Pelin, Irina M; Nicolescu, Alina; Hitruc, Gabriela

    2015-06-01

    Water-soluble curdlan derivatives containing quaternary ammonium groups with a degree of substitution up to 0.15 were synthesized using different cationic agents in alkaline medium. The chemical structure of curdlan derivatives was confirmed by FTIR, (13)C and (1)H NMR spectroscopy. The influence of some reaction conditions (temperature, time, and molar ratio) on the degree of substitution and the viscosimetic behaviour were studied. The degree of substitution increased with the amount of the cationization agent per anhydroglucose unit and was higher when the glycidyl reagents were used, compared with the case when the reagents contained chloro-hydroxypropyl groups. The viscosity behaviour of these new derivatives of curdlan in aqueous solutions and the values of intrinsic viscosities calculated using different semi-empirical equations denote a high hydrodynamic dimension of the macromolecular coils. The interaction of these cationic curdlan derivatives with an anionic curdlan (monobasic curdlan phosphate) was studied in situ by turbidimetric measurements and after 24h by optical density and dynamic light scattering. The formation of polyelectrolyte complexes was influenced by the degree of substitution, the nature of the quaternary substituent, and by the ionic strength of the aqueous solution. The morphology of the polyelectrolyte complexes particles in dry state was examined by atomic force microscopy. PMID:25843873

  9. Active Faulting and Quaternary Landforms Deformation Related to the Nain Fault

    Directory of Open Access Journals (Sweden)

    Abolghasem Gourabi

    2011-01-01

    Full Text Available Problem statement: Landforms developed across terrain defining boundary the Nain fault have imprints of recent tectonic activity in the west region of Central Iran. Depositional landforms such as alluvial fans bear signatures of later phases of tectonic activity in the form of faulting of alluvial fan deposits and development of fault traces and scarps within 100 km long and a NW-SE-trending zone, 1000-2000 m wide. Approach: We are addressing the neotectonic landforms based on detailed field work carried out in the Nain exposed active fault segments which brought forward some outstanding morphtectonic evidence of quaternary tectonically activities. Tectonic geomorphology applied to the Nain fault suggests recent subsurface activity along the Nain fault and an interconnecting faulting network of roughly NW-SE-trending, right-lateral, strike-slip segments and mostly NW-SE-oriented, transtensional to normal faults. Results: Evidence for recent activity is provided by faulted Pleistocene-Holocene deposits, fresh scarps in Late Quaternary deposits, 8-15 m lateral offsets locally affecting the drainage pattern of the area, ground creeping, aligning of series of spring faults, deflected streams and fault trace over recent alluvial fans. The existences of strike-slip faults system in the Nain area can be implications for seismic hazard. Conclusion: Motion along these structures suggests, in fact, that cumulative displacements include normal, transtensional and strike-slip components. Based on all evidence of active tectonics, earthquake risk and occurrence area is significant.

  10. New data concerning the Late Quaternary drainage evolution on the Someş River alluvial fan

    Directory of Open Access Journals (Sweden)

    Delia-Elena ROBU

    2014-11-01

    Full Text Available The study area is located in the north-eastern part of the Pannonian Basin, on the romanian teritory, with a surface of over 3,600 square kilometers. With elevations of 20-30 m above the Timiş and Criş plains, is the highest low-western romanian plains (100 – 160 m absolute altitudes, the surface extending on both sides of Someş River. This study aims to report new information on Late Quaternary evolution of fluvial discharge on the surface of Someş alluvial fan.Numerous relict fluvial morphologies were recognized on the surface ofSomeşRiveralluvial Plain, by analyzing mainly the fluvial morphologies visible on the second austro-hungarian military maps (reference moment: ca. 1860, and on recent ortophotoplans (reference moment: 2005. The identified palaeochannel types (braided, meandering and morphometry (large scale meanders vs. small scale meanders, the concentration of these relict features on distinct palaeodrainage directions, the relation of them with the recent fluvial drainage of the area (intersected, partly/ totally used by present day misfit channels, suggest a complex Late Quaternary history of the lower course ofSomeşRiver. 

  11. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    International Nuclear Information System (INIS)

    Highlights: • A series of PDMS-b-QPDMAEMA block copolymers were synthesized via RAFT polymerization. • The composition and morphology of the copolymer films strongly depended on the content of QPDMAEMA. • Migration of QPDMAEMA blocks toward surface was promoted when contacting with water. • Heterogeneous film surfaces with higher N+ content exhibited more obvious antimicrobial activity. - Abstract: Block copolymers PDMS-b-PDMAEMA were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization involving N,N-dimethylaminoethyl methacrylate (DMAEMA) by using poly(dimethylsiloxane) (PDMS) macro-chain transfer agent. And, the tertiary amino groups in PDMAEMA were quaternized with n-octyliodide to provide quaternary ammonium salts (QPDMAEMA). The well-defined copolymers generated composition variation and morphology evolvement on film surfaces, which were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The results indicated that the enrichment of QPDMAEMA brought about lower elemental ratios of Si/N on the film surfaces. The surface morphologies evolved with the variations of QPDMAEMA content, and the variation trend of film roughness was exactly opposite to that of water contact angle hysteresis. With regard to structure-antimicrobial relationships, the copolymer films had more evident antimicrobial activity against Gram-positive, Bacillus subtilis, and the surfaces with heterogeneous morphology and higher N+ content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings

  12. Paleoclimatic, paleovegetational and provenance change in the Ganga Plain during the late Quaternary

    Indian Academy of Sciences (India)

    Shailesh Agrawal; Prasanta Sanyal; Melinda K Bera; Jitendra K Dash; Srinivasan Balakrishnan

    2013-08-01

    Present study aims at reconstructing the paleomonsoonal rainfall, paleovegetation and provenance change during the late Quaternary. Towards this, Bhognipur core, collected from the southern Ganga Plain, have been sampled for soil carbonate (SC) and soil. The 18O values of SC (18OSC) range from −7.6 to −4.9‰. The variations in 18OSC values suggest that during the late Quaternary, the monsoon intensified during MIS 3 and MIS 1 and the maximum lowering of rainfall intensity is observed during MIS 2. The 13C value of SC (13CSC), organic matter dispersed in the soil (13CSOM) and occluded in the carbonate nodules (13CNOM) ranges from −4.1 to +1.4‰, −25.6 to −16.3‰, and −27.7 to −25.0‰, respectively, implies mixed C3–C4 vegetation over the Ganga Plain. Variations in 13CSOM and 13CNOM values at same depth imply preservation problem of pristine organic matter signature. Therefore, it is important to assess the preservation of residual organic matter before using it for paleovegetational reconstruction. The monsoon-vegetation relationship indicates that relative abundances of C3–C4 vegetation were mainly driven by variations in monsoonal rainfall intensity. Using 87Sr/86Sr in SC, we show that the Himalayan river was supplying sediments in the southern part of the Ganga Plain during MIS 3.

  13. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Xiaoshuai; Li, Yancai; Zhou, Fang; Ren, Lixia; Zhao, Yunhui, E-mail: zhaoyunhui@tju.edu.cn; Yuan, Xiaoyan

    2015-02-15

    Highlights: • A series of PDMS-b-QPDMAEMA block copolymers were synthesized via RAFT polymerization. • The composition and morphology of the copolymer films strongly depended on the content of QPDMAEMA. • Migration of QPDMAEMA blocks toward surface was promoted when contacting with water. • Heterogeneous film surfaces with higher N{sup +} content exhibited more obvious antimicrobial activity. - Abstract: Block copolymers PDMS-b-PDMAEMA were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization involving N,N-dimethylaminoethyl methacrylate (DMAEMA) by using poly(dimethylsiloxane) (PDMS) macro-chain transfer agent. And, the tertiary amino groups in PDMAEMA were quaternized with n-octyliodide to provide quaternary ammonium salts (QPDMAEMA). The well-defined copolymers generated composition variation and morphology evolvement on film surfaces, which were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The results indicated that the enrichment of QPDMAEMA brought about lower elemental ratios of Si/N on the film surfaces. The surface morphologies evolved with the variations of QPDMAEMA content, and the variation trend of film roughness was exactly opposite to that of water contact angle hysteresis. With regard to structure-antimicrobial relationships, the copolymer films had more evident antimicrobial activity against Gram-positive, Bacillus subtilis, and the surfaces with heterogeneous morphology and higher N{sup +} content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings.

  14. Effect of the N-terminal residues on the quaternary dynamics of human adult hemoglobin

    Science.gov (United States)

    Chang, Shanyan; Mizuno, Misao; Ishikawa, Haruto; Mizutani, Yasuhisa

    2016-05-01

    The protein dynamics of human hemoglobin following ligand photolysis was studied by time-resolved resonance Raman spectroscopy. The time-resolved spectra of two kinds of recombinant hemoglobin expressed in Escherichia coli, normal recombinant hemoglobin and the α(V1M)/β(V1M) double mutant, were compared with those of human adult hemoglobin (HbA) purified from blood. A frequency shift of the iron-histidine stretching [ν(Fe-His)] band was observed in the time-resolved spectra of all three hemoglobin samples, indicative of tertiary and quaternary changes in the protein following photolysis. The spectral changes of the α(V1M)/β(V1M) double mutant were distinct from those of HbA in the tens of microseconds region, whereas the spectral changes of normal recombinant hemoglobin were similar to those of HbA isolated from blood. These results demonstrated that a structural change in the N-termini is involved in the second step of the quaternary structure change of hemoglobin. We discuss the implications of these results for understanding the allosteric pathway of HbA.

  15. Composition dependences of thermodynamical properties associated with Pb-free ternary, quaternary, and quinary solder systems

    Science.gov (United States)

    Dogan, A.; Arslan, H.

    2016-05-01

    In the present study, Chou's General Solution Model (GSM) has been used to predict the enthalpy and partial enthalpies of mixing of the liquid Ag-In-Sn ternary, Ag-In-Sn-Zn quaternary, and Ag-Au-In-Sn-Zn quinary systems. These are of technical importance to optimize lead-free solder alloys, in selected cross-sections: x In/ x Sn = 0.5/0.5 (ternary), Au-In0.1-Sn0.8-Zn0.1, Ag-In0.1-Sn0.8-Zn0.1 (quaternary), and t = x Au/ x In = 1, x In = x Sn = x Zn (quinary) at 1173, 773, and 773 K, respectively. Moreover, the activity of In content in the ternary alloy system Ag-In-Sn has been calculated and its result is compared with that determined from the experiment, while the activities of Ag contents associated with the alloys mentioned above have been calculated. The other traditional models such as of Colinet, Kohler, Muggianu, Toop, and Hillert are also included in calculations. Comparing those calculated from the proposed GSM with those determined from experimental measurements, it is seen that this model becomes considerably realistic in computerization for estimating thermodynamic properties in multicomponent systems.

  16. Calcium Nodules as a Proxy for Quaternary Paleoclimate Change on China's Loess Plateau.

    Science.gov (United States)

    He, Wenming; He, Hongming; Zhu, Mingyong

    2015-01-01

    Different proxies have been used to investigate Quaternary paleoclimate change. Here, we used weathering of calcium nodules in paleosols on China's Loess Plateau as a proxy for Quaternary paleoclimate changes to provide an alternative indicator of these changes. Paleosol and carbonate nodules were collected from Luochuan and Lantian counties in Shaanxi Province, China. We found that this approach allowed quantitative reconstruction of temperature, rainfall, soil mineral composition, and the effects of weathering and leaching. The changes in carbonate content in the loess and paleosol sequences were controlled by alternating dry and wet climatic conditions. Nodule formation conditions were directly affected by the leaching and migration of elements. The loess and paleosol sequences developed calcium nodules, and their formation was closely related to the rainfall and leaching characteristics of the paleoclimate. The paleoclimate and soil minerals affected the vegetation types and directly influenced changes in the soil. During formation of the calcium nodules, the surface vegetation evolved slowly, and the number of species and quantity of vegetation both decreased. PMID:26633304

  17. Calcium Nodules as a Proxy for Quaternary Paleoclimate Change on China’s Loess Plateau

    Science.gov (United States)

    He, Wenming; He, Hongming; Zhu, Mingyong

    2015-01-01

    Different proxies have been used to investigate Quaternary paleoclimate change. Here, we used weathering of calcium nodules in paleosols on China’s Loess Plateau as a proxy for Quaternary paleoclimate changes to provide an alternative indicator of these changes. Paleosol and carbonate nodules were collected from Luochuan and Lantian counties in Shaanxi Province, China. We found that this approach allowed quantitative reconstruction of temperature, rainfall, soil mineral composition, and the effects of weathering and leaching. The changes in carbonate content in the loess and paleosol sequences were controlled by alternating dry and wet climatic conditions. Nodule formation conditions were directly affected by the leaching and migration of elements. The loess and paleosol sequences developed calcium nodules, and their formation was closely related to the rainfall and leaching characteristics of the paleoclimate. The paleoclimate and soil minerals affected the vegetation types and directly influenced changes in the soil. During formation of the calcium nodules, the surface vegetation evolved slowly, and the number of species and quantity of vegetation both decreased. PMID:26633304

  18. Calcium Nodules as a Proxy for Quaternary Paleoclimate Change on China's Loess Plateau.

    Directory of Open Access Journals (Sweden)

    Wenming He

    Full Text Available Different proxies have been used to investigate Quaternary paleoclimate change. Here, we used weathering of calcium nodules in paleosols on China's Loess Plateau as a proxy for Quaternary paleoclimate changes to provide an alternative indicator of these changes. Paleosol and carbonate nodules were collected from Luochuan and Lantian counties in Shaanxi Province, China. We found that this approach allowed quantitative reconstruction of temperature, rainfall, soil mineral composition, and the effects of weathering and leaching. The changes in carbonate content in the loess and paleosol sequences were controlled by alternating dry and wet climatic conditions. Nodule formation conditions were directly affected by the leaching and migration of elements. The loess and paleosol sequences developed calcium nodules, and their formation was closely related to the rainfall and leaching characteristics of the paleoclimate. The paleoclimate and soil minerals affected the vegetation types and directly influenced changes in the soil. During formation of the calcium nodules, the surface vegetation evolved slowly, and the number of species and quantity of vegetation both decreased.

  19. Magnetostratigraphy of a long Quaternary sediment core in the South Yellow Sea

    Science.gov (United States)

    Liu, Jianxing; Liu, Qingsong; Zhang, Xunhua; Liu, Jian; Wu, Zhiqiang; Mei, Xi; Shi, Xuefa; Zhao, Quanhong

    2016-07-01

    Continental shelves serve as a bridge between the continent and ocean and sediments in this region are sensitive to land-sea interaction, sea-level variation and local subsidence. In this study, we present a comprehensive magnetic study of the longest sediment core (CSDP-1, 300.1 m) recovered from the South Yellow Sea. The major magnetic minerals in the studied sediments are magnetite, hematite and greigite. Greigite records a chemical remanent magnetization, which can be removed effectively by thermal demagnetization. The magnetostratigraphy defined in this study contains the Matuyama-Brunhes boundary (M/B, 781 ka) at ∼73.68 m, which is consistent with results from adjacent cores. The base of the Quaternary (∼2.6 Ma) in the Yellow Sea is recovered for the first time at a depth of 227.16 m. The basal age of the core is estimated to be ∼3.50 Ma. It indicates that the first transgression of the Yellow Sea occurred no later than ∼1.7 Ma. Succeeding large amplitude regressions occurred in some cold periods such as during MIS 20, MIS 18, and MIS 10. Our results provide the first chronology that brackets the entire Quaternary and we reconstruct the sedimentary evolution of the Yellow Sea with robust age constraints, which provides an important framework for further paleoenvironmental and tectonic studies.

  20. Agricultural contaminants in Quaternary aquitards: A review of occurrence and fate in North America

    Science.gov (United States)

    Rodvang, S. J.; Simpkins, W. W.

    2001-01-01

    The intensity of agriculture has increased significantly during the past 30 years, resulting in increased detection of agricultural contaminants (nutrients, pesticides, salts, trace elements, and pathogens) in groundwater. Till, glaciolacustrine, and loess deposits of Quaternary age compose the most common surficial deposits underlying agricultural areas in North America. Quaternary aquitards generally contain higher concentrations of solid organic carbon (SOC, as much as 1.4%), dissolved organic carbon (DOC, as much as 205 mg/L), and reduced sulfur (as much as 0.9%) than do aquifers. Their potential to sorb pesticides increases with the percent of older SOC, because diagenesis increases Koc. Denitrification consistently reduces nitrate to non-detectable levels in unweathered Quaternary aquitards. Organic carbon of Quaternary age is a more labile electron donor than carbon from shale clasts. Pyrite is a more labile electron donor than carbon in many instances. Unweathered Quaternary aquitards provide a high degree of protection for underlying aquifers, due to their large reserves of SOC and reduced sulfur for sorption and denitrification, combined with their typically low hydraulic conductivity. In contrast, agricultural contaminants are common in weathered Quaternary aquitards. Lower reserves of reduced sulfur and sorptive/labile organic carbon, and a higher bulk K due to fractures, limit their ability to attenuate nitrate and pesticides. Subsurface drainage, which is common in Quaternary aquitards because of high water tables, bypasses the attenuation capacity of Quaternary aquitards and facilitates the transport of agricultural contaminants to surface water. Résumé. L'agriculture s'est significativement accrue au cours des dernières 30 années, provoquant une détection plus fréquente dans les eaux souterraines de contaminants agricoles (engrais, pesticides, sels, éléments en traces et germes pathogènes). Les moraines, les formations glacio-lacustres et

  1. [Synthesis, characterization and antimicrobial activity of konjac glucomannan derivative with quaternary ammonium salts].

    Science.gov (United States)

    Lei, Wan-Xue; Xu, Xia; Lin, Fang; Yang, Qin-Huan; Li, Zhen-Jun; Zhang, Ting-You

    2008-05-01

    Methacryloxylethyl tetradecyl dimethyl ammonium bromide was grafted onto konjac glucomannan using ceric ammonium nitrate as an initiator, and the konjac glucomannan derivative with quaternary ammonium salts was obtained. The konjac glucomannan derivative was investigated by hydrogen nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), and Zeta sizer nano series. The antimicrobial properties of the konjac glucomannan derivative against selected microorganisms were tested by the quantitative suspension method. The results revealed that (1) methacryloxylethyl tetradecyl dimethyl ammonium bromide can be grafted onto the surface of the konjac glucomannan, and the percentage grafting increases with increasing the amount of methacryloxylethyl tetradecyl dimethyl ammonium bromide. (2) The Zeta potential showed that the isoelectric point of the konjac glucomannan and the modified konjac glucomannan is pH 4. 5 and pH 9. 9, respectively. The shift of the isoelectric point is due to the quaternary ammonium groups. (3) The obtained konjac glucomannan derivative has significant inhibition effect on the growth of microorganisms, and the bactericidal rates in 15 min for E. coil (8099), S. aureus (ATCC 6538) and C. albicans (ATCC10231) were 99.99%, 99.99% and 98.13%, respectively. PMID:18720795

  2. Faults in Quaternary cover as a relfection of basement tectonics: Kolguev island, barents sea

    Science.gov (United States)

    Krapivner, R. B.; Skorobogat'ko, A. V.

    2012-09-01

    The paper is concerned with the results of the detailed study of dislocations in the Pliocene-Quaternary loose sediments exposed as cliffs extending for ˜30 km along the rectilinear shore of Kolguev Island. According to seismic data, this lineament is related to the Coastal Fault in the lower part of the sedimentary cover. A system of faults longitudinal, diagonal, and transverse relative to the shoreline is established from observations at the cliffs. Their arrangement in plan view corresponds to the geometry of the right-lateral shear zone, the axis of which almost coincides with the shoreline. This has allowed us to identify the faults as secondary disturbances in the region of dynamic effect of the Coastal Fault in the basement. The kinematics of the secondary faults and their dip azimuth are consistent with echeloned geometry in plan view. The low-angle dip of the reverse-strike-slip faults observed at the outcrops is caused by their near-surface flattening toward the subsided block. The shallow-seated dislocations are related to ductile lateral shear in the vertical plane. The lower layers of the sedimentary cover mimic the horizontal movements in the basement more closely than the upper layers. The data obtained indicate high neotectonic activity of the Barents Sea shelf and specify the geodynamic setting of the region in the Pliocene and Quaternary.

  3. Geology shapes biogeography: Quaternary river-capture explains New Zealand's biologically 'composite' Taieri River

    Science.gov (United States)

    Waters, Jonathan M.; Wallis, Graham P.; Burridge, Christopher P.; Craw, Dave

    2015-07-01

    Geological processes are hypothesised to strongly affect species distributions. In particular, a combination of geological and biological data has suggested that tectonic processes can drive vicariant isolation and speciation in freshwater-limited taxa. Here we synthesise geological and biological evidence to demonstrate a composite geological and biological history for New Zealand's 290-km long Taieri River. Specifically, we assess evidence from structural geology and petrology, combined with phylogenetic and biogeographic analysis of galaxiid fishes, to show that the modern Taieri River was formed via capture of the ancestral Kye Burn during the mid-late Quaternary. Molecular dating analyses support a late-Quaternary timeframe for the geologically-mediated divergence between formerly-connected sister taxa Galaxias depressiceps and G. 'teviot'. Fish biogeography lends further support to the geological hypothesis, as there is a substantial biogeographic disjunction between the lower- (ancestral) and upper (captured) portions of the Taieri River. Geological and biological data are assessed independently yet yield consilient patterns and timeframes for the evolutionary events inferred. Broadly, this study highlights the interplay between physical and biological processes in a geologically dynamic setting.

  4. North atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles

    Science.gov (United States)

    Dwyer, G.S.; Cronin, T. M.; Baker, P.A.; Raymo, M.E.; Buzas, Jeffrey S.; Correge, T.

    1995-01-01

    Variations in the ratio of magnesium to calcium (Mg/Ca) in fossil ostracodes from Deep Sea Drilling Project Site 607 in the deep North Atlantic show that the change in bottom water temperature during late Pliocene 41,000-year obliquity cycles averaged 1.5??C between 3.2 and 2.8 million years ago (Ma) and increased to 2.3??C between 2.8 and 2.3 Ma, coincidentally with the intensification of Northern Hemisphere glaciation. During the last two 100,000-year glacial-to-interglacial climatic cycles of the Quaternary, bottom water temperatures changed by 4.5??C. These results show that glacial deepwater cooling has intensified since 3.2 Ma, most likely as the result of progressively diminished deep-water production in the North Atlantic and of the greater influence of Antarctic bottom water in the North Atlantic during glacial periods. The ostracode Mg/Ca data also allow the direct determination of the temperature component of the benthic foraminiferal oxygen isotope record from Site 607, as well as derivation of a hypothetical sea-level curve for the late Pliocene and late Quaternary. The effects of dissolution on the Mg/Ca ratios of ostracode shells appear to have been minimal.

  5. Shaping quaternary assemblies of water-soluble non-peptide helical foldamers by sequence manipulation

    Science.gov (United States)

    Collie, Gavin W.; Pulka-Ziach, Karolina; Lombardo, Caterina M.; Fremaux, Juliette; Rosu, Frédéric; Decossas, Marion; Mauran, Laura; Lambert, Olivier; Gabelica, Valérie; Mackereth, Cameron D.; Guichard, Gilles

    2015-11-01

    The design and construction of biomimetic self-assembling systems is a challenging yet potentially highly rewarding endeavour that contributes to the development of new biomaterials, catalysts, drug-delivery systems and tools for the manipulation of biological processes. Significant progress has been achieved by engineering self-assembling DNA-, protein- and peptide-based building units. However, the design of entirely new, completely non-natural folded architectures that resemble biopolymers (‘foldamers’) and have the ability to self-assemble into atomically precise nanostructures in aqueous conditions has proved exceptionally challenging. Here we report the modular design, formation and structural elucidation at the atomic level of a series of diverse quaternary arrangements formed by the self-assembly of short amphiphilic α-helicomimetic foldamers that bear proteinaceous side chains. We show that the final quaternary assembly can be controlled at the sequence level, which permits the programmed formation of either discrete helical bundles that contain isolated cavities or pH-responsive water-filled channels with controllable pore diameters.

  6. Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans.

    Science.gov (United States)

    Beyth, Nurit; Yudovin-Farber, Ira; Bahir, Ran; Domb, Abraham J; Weiss, Ervin I

    2006-07-01

    The antibacterial activity of quaternary ammonium polyethylenimine (PEI) nanoparticles embedded at 1%w/w with clinically used bonding, flowable and hybrid dental composite resins and cured by light polymerization was studied. The antibacterial activity was tested with Streptoccocus mutans by: (i) the agar diffusion test (ADT); (ii) the direct contact test; (iii) bacterial growth in the materials elute; (iv) and scanning electron microscope (SEM). Using the direct contact test, antibacterial activity (p<0.001) was found in all three types of composite resins incorporated with the synthesized nanoparticles. The effect lasted for at least 1 month. SEM demonstrated bacterial debris and no streptococcal chains at 24h of bacterial contact. The addition of 1%w/w of nanoparticles did not affect the flexural modulus and the flexural strength of the dental composite materials. The results indicate that quaternary ammonium PEI nanoparticles immobilized in resin-based materials have a strong antibacterial activity upon contact without leach-out of the nanoparticles and without compromise in mechanical properties. PMID:16564083

  7. Quaternary deposits and weathered bedrock material as a source of dangerous radon emissions in Estonia

    Directory of Open Access Journals (Sweden)

    Petersell Valter

    2015-06-01

    Full Text Available The risk of dangerous radon emissions in Estonia is high, being among the highest in Europe. In almost 33 per cent of Estonian land area, the content of radon in soil-contained air exceeds the safe limit for unrestricted construction (50 kBq/m3. In such high radon-risk areas the concentration of radon in soil-contained air ranges from 50 to 400 kBq/m3, in a few cases reaching up to 2,100 kBq/m3 exceeding the permitted level for residential areas. The situation is particularly serious in the northernmost part of the country, where uranium-rich graptolite argillite (Dictyonema shale and the Obolus phosphorite are close to ground surface and their particles are constituent parts of Quaternary deposits. Radon emissions from bedrock have been investigated in detail, but to date Quaternary strata as a source of radon emissions are poorly studied. According to our measurements the highest concentrations of radon are related to tills containing clasts and fines of graptolite argillite and phosphorite. Glacial deposits include also granitoidal material, containing U, Th and K, which have been transported by glaciers from the outcrop areas of crystalline basement rocks in Finland and the Gulf of Finland. Due to weathering, outwash and repeated redeposition other genetic types are poorer in radioactive elements and they are weaker sources of radon.

  8. Structural contour, isopach and feature maps of quaternary sediments in Western Lake Ontario

    International Nuclear Information System (INIS)

    A systematic high-resolution acoustic reconnaissance survey of Quaternary sediments (> 50 m thick, in places) and the underlying bedrock surface was completed for western Lake Ontario between Burlington and Port Hope, Ontario, to determine if geophysical lineaments through the area of Pickering and Darlington nuclear power stations are potentially seismically active. A total of 2530 line-km of data were obtained along N-S and E-W lines spaced 10 and 5 km respectively, using a high-resolution subbottom profiler (boomer and IKB-SEISTEC), a 100 kHz sidescan sonar (150-m range) with 3.5 kHz profiler, a 10 or 40 cu. in. sleeve gun seismic reflection system, and, intermittently, a marine magnetometer. Six piston cores up to 15-m long were collected to compare sediment lithology with key regional seismic reflectors. Sediments deposited over the past 13,000 years were imaged with vertical resolution in the order of 10-30 cm just below the lakebed and less than 1 m at the bedrock surface; resolution for the sleeve gun system is approximately 3-5 m. Digital processing and rescaling of selected seismic profiles aided interpretation. Structural contour maps for three Quaternary sequence boundaries and the bedrock surface were generated together with the related sequence isopach maps. Three additional maps portray lakebed features identified on sidescan sonar records and subsurface features identified on seismic profiles. All maps are at 1:250,000 scale. (author). 2 tabs., 48 figs., 12 maps

  9. Scalable Generalization of Hydraulic Conductivity in Quaternary Strata for Use in a Regional Groundwater Model

    Science.gov (United States)

    Jatnieks, J.; Popovs, K.; Klints, I.; Timuhins, A.; Kalvans, A.; Delina, A.; Saks, T.

    2012-04-01

    The cover of Quaternary sediments especially in formerly glaciated territories usually is the most complex part of the sedimentary sequences. In regional hydro-geological models it is often assumed as a single layer with uniform or calibrated properties (Valner 2003). However, the properties and structure of Quaternary sediments control the groundwater recharge: it can either direct the groundwater flow horizontally towards discharge in topographic lows or vertically, recharging groundwater in the bedrock. This work aims to present calibration results and detail our experience while integrating a scalable generalization of hydraulic conductivity for Quaternary strata in the regional groundwater modelling system for the Baltic artesian basin - MOSYS V1. We also present a method for solving boundary transitions between spatial clusters of lithologically similar structure. In this study the main unit of generalization is the spatial cluster. Clusters are obtained from distance calculations combining the Normalized Compression Distance (NCD) metric, calculated by the CompLearn parameter-free machine learning toolkit, with normalized Euclidean distance measures for coordinates of the borehole log data. A hierarchical clustering solution is used for obtaining cluster membership identifier for each borehole. Using boreholes as generator points for Voronoi tessellation and dissolving resulting polygons according to their cluster membership attribute, allows us to obtain spatial regions representing a certain degree of similarity in lithological structure. This degree of similarity and the spatial heterogeneity of the cluster polygons can be varied by different flattening of the hierarchical cluster model into variable number of clusters. This provides a scalable generalization solution which can be adapted according to model calibration performance. Using the dissimilarity matrix of the NCD metric, a borehole most similar to all the others from the lithological structure

  10. A study of adsorption equilibrium on quaternary ammonium resin in uranyl sulphate solution by chemical equivalent method

    International Nuclear Information System (INIS)

    The exchange equilibrium between SO42- and HSO4- on quaternary ammonium strong base resin and the effect of ClO4- on the equilibrium are studied by chemical equivalent method. On the basis of the results the adsorption equilibrium of the resin in uranyl sulphate solution which is similar to the solution in uranium hydrometallurgy process is also studied

  11. Stable isotopes reflect the ecological stability of two high-elevation mammals from the late Quaternary of Colorado

    Science.gov (United States)

    McLean, Bryan S.; Emslie, Steven D.

    2012-05-01

    The vertebrate fossil record of Cement Creek Cave, Colorado, spans from > 45,000 yr ago to the present and represents the richest stratified series of high-elevation (> 2900 m) mammal remains known from the late Quaternary of North America. Stable carbon and oxygen isotope analyses of tooth enamel were used to assess potential ecological responses of two species found commonly throughout the cave, Yellow-bellied marmots (Marmota flaviventris) and Bushy-tailed woodrats (Neotoma cinerea), to late Quaternary climate and environmental changes of the Southern Rocky Mountains. Results indicate that despite such perturbations, the dietary ecologies of both species were maintained across this period. Neither taxon shifted to consuming C4 taxa or different C3 functional groups; similarly, no significant shifts in surface water use were detected. Variations in enamel δ13C were observed, however, that represent the physiological responses of high-elevation plants to changing levels of late Quaternary atmospheric CO2. While our findings extend both the geographic and elevational record of this plant CO2 response, they simultaneously highlight the ecological stability of high-elevation M. flaviventris and N. cinerea during climate changes of late Quaternary magnitude.

  12. Tectonic and climatic controls on late quaternary sedimentary processes in a neotectonic intramontane basin. (The Pitalito Basin, South Colombia).

    NARCIS (Netherlands)

    Bakker, J.

    1990-01-01

    The present study deals with the influence of tectonics and climatic changes on sedimentation patterns in the Quaternary Pitalito Basin (lat. 1°52'N, long. 76°02'W). This intramontane sedimentary basin is 15 km in width and 20 kin in length and is located in the Eastern Cordillera of the southern Co

  13. Research on the neutron flux, secular equilibrium of chlorine-36 and groundwater age of the deep quaternary sediments, Hebei plain

    International Nuclear Information System (INIS)

    For the study of the neutron flux, secular equilibrium of chlorine-36 in the deep quaternary sediments of Hebei plain, the main chemical composition of water sand and confining bed was determined by neutron activation analysis. The mean neutron flux is 2.79 x 10-5 cm-2s-1 which was calculated by the chemical composition of the strata. The mean 36Cl/Cl ratio in secular equilibrium is 1.27 x 10-14 in the deep quaternary sediments, Hebei Plain. For the study of the groundwater age of the deep Quaternary sediments of Hebei Plain, the 36Cl/Cl ratio of groundwater samples were determined by tandem accelerator mass spectrometry. The mixed groundwater 36Cl/Cl ratio of the second and the third aquifer of Quaternary sediments in Baoding district is 247 x 10-15, that of the fourth aquifer in Baoding city is 224 x 10-15 and the third aquifer in Cangzhou district is 40.5 x 10-15. The groundwater age of Baoding district was young and that of the third aquifer in Cangzhou was 229.2 ka

  14. Quaternary deposits in the Serra da Capivara National Park and surrounding area, Southeastern Piauí state, Brazil

    OpenAIRE

    Kenitiro Suguio; Alcina Magnólia Franca Barreto; Janaina C. Santos

    2012-01-01

    Serra da Capivara National Park and surrounding areas in Southeastern Piau State (Brazil) were subjected to morphostratigraphical, sedimentological, and geochronological studies about superficial deposits in order to interpret quaternary paleoenvironmental events. The following sedimentary deposits associated with morphostructural units were identified: colluvial fans at Serra Branca Valley and Structural Staircases, and eluvial-colluvial deposits at Reverse of the Cuesta. There are also coll...

  15. Microstructural aspects of manganese metal during its electrodeposition from sulphate solutions in the presence of quaternary amines

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Quaternary amines produced smooth and bright manganese electrodeposits. • TEABr produced smooth and bright deposits with euhedral shaped crystals. • TBABr produced dendritic deposits with elongated poly-nodular crystals. • All the quaternary amines behaved as cathode polarisers. • TEABr was found to be the most efficient organic additive. - Abstract: In the present study investigation was made on the electrodeposition of manganese from sulphate solutions in the presence of quaternary amines TEABr, TPABr and TBABr. The concentrations of these additives were varied over a relatively broad range to evaluate their effect on the deposit morphology and preferred crystal orientations of the electrodeposited metal. TEABr resulted in bright and smooth manganese electrodeposits giving euhedral shape to the crystals with distinct triple junction points. TPABr also showed similar results at lower concentrations. However, TBABr resulted in the formation of dendritic growths with elongated poly-nodular crystals similar to that of Paragorgia corals having uniform multistep growths. The presence of these quaternary amines in the electrolyte causes polarisation of the cathode. TBABr being the strongest cathode polariser adsorbs strongly on the cathode resulting in poor deposit quality. TEABr was found to be the most efficient additive producing the desired quality manganese electrodeposit

  16. Quaternary climate change and Heinrich events in the southern Balkans : Lake Prespa diatom palaeolimnology from the last interglacial to present

    NARCIS (Netherlands)

    Cvetkoska, Aleksandra; Levkov, Zlatko; Reed, Jane M.; Wagner, Bernd; Panagiotopoulos, Konstantinos; Leng, Melanie J.; Lacey, Jack H.

    2015-01-01

    Lake Prespa, in the Balkans, contains an important palaeo-archive in a key location for understanding Quaternary climate variability in the transition between Mediterranean and central European climate zones. Previous palaeoenvironmental research on sediment cores indicates that the lake is highly s

  17. Age determination and development of experimental methods for quaternary fault and formation

    International Nuclear Information System (INIS)

    Correlation of palaeo-shoreline elevations indicates that the MQt4 terrace in Suryum site has formed during MIS 5e, which is supported by stratigraphically concordant OSL ages for NQt3 terrace sediments in Yonghan area. Sedimentological features of the trench site of the Eupcheon fault suggest multiple fault movements during the Late Quaternary. All of these observations imply that uplift rate in the middle part of the coast has been much larger than that in the northern part during 125 ka ∼ 80 ka, requiring the revision of conventional view that the Korean peninsula is tectonically very stable. The ESR data suggest that the Ilkwang fault zone has been formed by the initial surface fault activity at 2-3 Ma and reactivated at least 4 times at 1.2-1.3 Ma, 1 Ma, 0.6 Ma and 0.5 Ma, with part of adjacent NNE and NE trending faults. The Eupcheon fault has been reactivated along the boundary between fault breccia originated from Cretaceous sedimentary rocks and Tertiary lithic tuff at around 2 Ma, 1.3 Ma, and 1 Ma. It has been reactivation again along the boundary between Cretaceous sandstone and fault breccia at 0.8 Ma, and between fault breccia and Tertiary lithic tuff at 0.6 Ma. During the late Quaternary after MIS 5e, the Eupcheon fault reactivated along the boundary between fault gouges, cutting Quaternary marine terrace deposits. The ESR data for the Eupcheon fault, however, should be carefully reexamined because it is probable that the samples contain clay components of weathering, not cataclastic origin. A weathering profile developed in the Suryum site was disturbed by tectonic movement that appears to be a simple one-time reverse faulting event based on field observations. A comparative analysis of the mineralogy, micromorphology, and chemistry of the weathering profile and fault gouge, however, reveals that both the microfissures in the deformed weathering profile and larger void spaces along the fault plane were filled with multi-stage accumulations of

  18. The highs and lows of Quaternary sea-level reconstruction (Invited)

    Science.gov (United States)

    Dorale, J. A.; Onac, B. P.

    2010-12-01

    Because of its relationship to continental ice volume, an accurate Quaternary sea level curve has been a long-term goal of scientists interested in ice ages and their causes. But the perfect method of sea level reconstruction does not exist - each technique has its own set of strengths and limitations. The continuous character of deep sea oxygen isotopes is a clear strength, but sea level is inferred indirectly from a combined signal of ice volume and temperature, and the dating is not absolute. U/Th-dated fossil coral reefs capture the position of sea level directly and with absolute dating, but a number of factors commonly hinder an ultra-precise determination of both the height and the age of the sea level stand, and reef records are highly discontinuous. Together, these two techniques have played a huge, pioneering role in establishing the current framework for understanding Quaternary sea level fluctuations. We present here the emerging technique of using U/Th-dated speleothem encrustations in coastal caves to capture sea level changes, based on recent work in Mallorca, Spain. Like reefs, the speleothem encrustation technique is discontinuous in its coverage of sea level through time, but the method potentially pin-points both the position and the age of a particular past sea-level stand with razor-sharp precision. Our recent work at Mallorca suggests that ice-equivalent sea level from ~80-82 ka during MIS 5a was ~ 1 m higher than present sea level, and only 1-2 m lower than sea level during MIS 5e. Furthermore, sea level positions reconstructed during MIS 5b and MIS 4 suggest rates of sea level change approaching 2 m per century during the MIS 5b-5a-4 transitions, however, these estimates depend critically on the magnitudes of the analytical dating errors. Continued work will focus on reducing sampling and analytical errors to refine the inferred rates of sea level rise and fall during this and other periods of rapid sea level change, and to address the issue

  19. Influence of quaternary sea-level variations on a land bird endemic to Pacific atolls

    Science.gov (United States)

    Cibois, Alice; Thibault, Jean-Claude; Pasquet, Eric

    2010-01-01

    Little is known about the effect of quaternary climate variations on organisms that inhabited carbonate islands of the Pacific Ocean, although it has been suggested that one or several uplifted islands provided shelter for terrestrial birds when sea-level reached its highest. To test this hypothesis, we investigated the history of colonization of the Tuamotu reed-warbler (Acrocephalus atyphus) in southeastern Polynesia, and found high genetic structure between the populations of three elevated carbonate islands. Estimates of time since divergence support the hypothesis that these islands acted as refugia during the last interglacial maximum. These findings are particularly important for defining conservation priorities on atolls that endure the current trend of sea-level rise owing to global warming. PMID:20554555

  20. Antibacterial cotton fibers treated with silver nanoparticles and quaternary ammonium salts.

    Science.gov (United States)

    Kang, Chan Kyu; Kim, Sam Soo; Kim, Soojung; Lee, Jintae; Lee, Jin-Hyung; Roh, Changhyun; Lee, Jaewoong

    2016-10-20

    Cotton fibers were treated chemically with glycidyltrimethylammonium chloride (GTAC), a quaternary ammonium salt, and coated with silver nanoparticles/3-mercaptopropyltrimethoxysilane (3-MPTMS) to increase the antibacterial efficacy. The coating process was accomplished by soaking the cotton fibers into a GTAC solution followed by a dry-cure method, and silver colloid/3-MPTMS solution was then applied at 43°C for 90min. The properties of the cotton fibers were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis. SEM showed a rough surface when the cotton fibers were treated with GTAC/3-MPTMS/silver nanoparticles due to the increasing surface attachment. The existence of silver and 3-MPTMS on the cotton fibers was confirmed by XPS. The cotton fibers treated with both GTAC and silver nanoparticles showed synergistic antibacterial properties against P. aeruginosa. PMID:27474649

  1. Characteristics of Late Quaternary Activity of the Luhuatai Buried Fault Revealed by Drilling

    Institute of Scientific and Technical Information of China (English)

    Lei Qiyun; Chai Chizhang; Du Peng; Wang Yin; Meng Guangkui

    2012-01-01

    The Luhuatai fault is one of the important buried tectonics in the Yinchuan basin. Based on the results of shallow seismic exploration, we conducted composite drilling section exploration and dating of the samples from boreholes. Some useful data was obtained, such as the depth of the upper breaking point, the latest activity age, displacement in the late Quaternary, and slip rates, etc. This study shows that the activity is different between the north and south segment along the Luhuatai fault. The north segment is a Holocene fault, while the south segment is a late mid-Pleistocene fault. From north to south along the north segment of Luhuatai fault, the activity has been enhanced, and the faulting is stronger in late Pleistocene than Holocene.

  2. New data on the most ancient early quaternary glaciation in Gornyi Altai

    Science.gov (United States)

    Zykin, V. S.; Zykina, V. S.; Smolyaninova, L. G.

    2016-01-01

    The data presented in this work introduce substantial corrections into the Upper Cenozoic stratigraphy and geological history of Gornyi Altai. They provide evidence for the most ancient Early Pleistocene glaciation in this region. This follows from finds of faceted boulders buried in the Bashkaus Formation. Pale-omagnetic investigations revealed in the latter a wide zone of negative polarity corresponding to the Matuyama Chron in the magnetostratigraphic scale and made it possible to correlate the formation with the Lower Pleistocene in the standard stratigraphic scale. It is shown that global cooling at the beginning of the Quaternary Period stimulated development of glaciation on the southern slope of the Kuraiskii Range exceeding in size its present-day scale.

  3. Efflux pump induction by quaternary ammonium compounds and fluoroquinolone resistance in bacteria.

    Science.gov (United States)

    Buffet-Bataillon, Sylvie; Tattevin, Pierre; Maillard, Jean-Yves; Bonnaure-Mallet, Martine; Jolivet-Gougeon, Anne

    2016-01-01

    Biocides, primarily those containing quaternary ammonium compounds (QAC), are heavily used in hospital environments and various industries (e.g., food, water, cosmetic). To date, little attention has been paid to potential implications of QAC use in the emergence of antibiotic resistance, especially fluoroquinolone-resistant bacteria in patients and in the environment. QAC-induced overexpression of efflux pumps can lead to: cross resistance with fluoroquinolones mediated by multidrug efflux pumps; stress response facilitating mutation in the Quinolone Resistance Determining Region; and biofilm formation increasing the risk of transfer of mobile genetic elements carrying fluoroquinolone or QAC resistance determinants. By following the European Biocidal Product Regulation, manufacturers of QAC are required to ensure that their QAC-based biocidal products are safe and will not contribute to emerging bacterial resistance. PMID:26674470

  4. Species-specific responses of Late Quaternary megafauna to climate and humans

    DEFF Research Database (Denmark)

    Lorenzen, Eline D; Nogués-Bravo, David; Orlando, Ludovic;

    2011-01-01

    Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary period remain contentious. Here we use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped...... human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We...... find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, emphasizing the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change....

  5. High spin polarization in CoFeMnGe equiatomic quaternary Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bainsla, Lakhan [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Suresh, K. G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A. K. [Department of Condensed Matter and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India); Manivel Raja, M. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Varaprasad, B. S. D. Ch. S.; Takahashi, Y. K.; Hono, K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2014-11-28

    We report the structure, magnetic property, and spin polarization of CoFeMnGe equiatomic quaternary Heusler alloy. The alloy was found to crystallize in the cubic Heusler structure (prototype LiMgPdSn) with considerable amount of DO{sub 3} disorder. Thermal analysis result indicated the Curie temperature is about 750 K without any other phase transformation up to melting temperature. The magnetization value was close to that predicted by the Slater-Pauling curve. Current spin polarization of P = 0.70 ± 0.01 was deduced using point contact andreev reflection measurements. The temperature dependence of electrical resistivity has been fitted in the temperature range of 5–300 K in order to check for the half metallic behavior. Considering the high spin polarization and Curie temperature, this material appears to be promising for spintronic applications.

  6. Perfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents

    Energy Technology Data Exchange (ETDEWEB)

    Maayan, Galia; Fish, Richard H.; Neumann, Ronny

    2003-05-28

    Perfluorinated quaternary ammonium cations, [CF{sub 3}(CF{sub 2}){sub 7}(CH{sub 2}){sub 3}]{sub 3}CH{sub 3}N{sup +} (RFN{sup +}), were synthesized and used as counter cations for the [WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW{sub 9}O{sub 34}){sub 2}]{sup 12-} (M = Mn(II), Zn(II)), polyoxometalate. The (RFN{sup +}){sub 12}[WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW9O{sub 34}){sub 2}] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected both by the hydrophobicity of the solvent and the substrate.

  7. U-series dating of late Quaternary travertine in co-seismic fissures

    International Nuclear Information System (INIS)

    Earthquake faulting plays a key role in the transport of hydrothermal fluids and formation of brittle fracture systems, which act as sites for mineral deposition. Textural evidence from hydrothermal veins suggests that fluid flow in fault-related fracture systems generally occurs episodically. Therefore vein deposits in tectonically active areas may provide great opportunities for examining the evolution of earthquake-related fracturing. U-series dating of the fracture-filling carbonate deposits represents a powerful means to constrain the timing and recurrent intervals of the seismic activities. This paper shows that U-series age determination of travertine deposits in co-seismic fissures is an important geochronological technique to establish timing of fissure generation related to late Quaternary seismic events. (author). 8 refs., 2 figs

  8. High spin polarization in CoFeMnGe equiatomic quaternary Heusler alloy

    International Nuclear Information System (INIS)

    We report the structure, magnetic property, and spin polarization of CoFeMnGe equiatomic quaternary Heusler alloy. The alloy was found to crystallize in the cubic Heusler structure (prototype LiMgPdSn) with considerable amount of DO3 disorder. Thermal analysis result indicated the Curie temperature is about 750 K without any other phase transformation up to melting temperature. The magnetization value was close to that predicted by the Slater-Pauling curve. Current spin polarization of P = 0.70 ± 0.01 was deduced using point contact andreev reflection measurements. The temperature dependence of electrical resistivity has been fitted in the temperature range of 5–300 K in order to check for the half metallic behavior. Considering the high spin polarization and Curie temperature, this material appears to be promising for spintronic applications

  9. Late Quaternary environments and prehistoric occupation in the lower White Nile valley, central Sudan

    Science.gov (United States)

    Williams, Martin A. J.; Usai, Donatella; Salvatori, Sandro; Williams, Frances M.; Zerboni, Andrea; Maritan, Lara; Linseele, Veerle

    2015-12-01

    Despite the major contributions provided over fifty years ago by A.J. Arkell and J.D. Tothill to our understanding of late Quaternary environments and prehistoric occupation near the confluence of the Blue and White Nile in central Sudan, three key questions have remained unresolved since then. (a) Was the decline in Nile flood levels from early Holocene times onwards caused by a reduction in Nile discharge, or by channel incision, or both? (b) Was the regional climate wetter during times of high Nile floods and drier during times of low Nile floods? (c) Given the high degree of disturbance of Mesolithic and later prehistoric sites, is it possible to identify primary-context, stratified and undisturbed occupation? Drawing upon dated evidence from three sites to the east of and three to the west of the lower White Nile, we provide a qualified answer to the first question and documented affirmative answers to the second and third questions.

  10. Late Quaternary fine silt deposits of Jammu, NW Himalaya: Genesis and climatic significance

    Indian Academy of Sciences (India)

    Rajinder K Ganjoo; Vinod Kumar

    2012-02-01

    The fine silt deposits of Jammu (J & K State, India) stretch all along the Siwalik foothills from Jammu to the Potwar Plateau in Pakistan. The post-Siwalik deposits, first discussed by de Terra and Paterson (1939), are attributed to wind action. The deposits termed as ‘Potwar loessic silt’ comprising sandy silt are essentially of late Quaternary age (75–18 ka) and are re-looked herein from the point of view of genesis and climatic significance. The sorting, skewness and kurtosis parameters of fine silts of Jammu suggest fluvial environment of the deposits wherein the water budget fluctuated. The weak pedogenesis of fine silts at certain intervals corroborate to periods of less or no sedimentation. The bivariant plot studies further suggest fluvial environment of deposition for the fine silt at Jammu, with regular fluctuations in the budget of river water that was perhaps in consonance with oscillations in the climate of the region.

  11. Design of Multi-Valued Quaternary Based Analog-to-Digital Converter

    Directory of Open Access Journals (Sweden)

    A. H.M.Z. Alam

    2009-01-01

    Full Text Available Problem statement: The design of multi-valued quaternary based Analog-to-Digital Converter (ADC circuit was presented. The ADC generates multi-valued logic outputs rather than the conventional binary output system to overall reduction in circuit complexity and size. Approach: Design was implemented using pipeline ADC architecture and was simulated using model parameters based on standard 0.13 µm CMOS process. Results: Performance analysis of the design showed desirable performance parameters in terms of response, low power consumption, and a sampling rate of 10 MHz at a supply voltage of 1.3V was achieved. Conclusion/Recommendations: The ADC design was suitable for the needs of mixed-signal integrated circuit design and can be implemented as a conversion circuit for systems based on multiple-valued logic design.

  12. Late Quaternary Paleohydrology of the Madre de Dios River, southwestern Amazon Basin, Peru

    Science.gov (United States)

    Rigsby, Catherine A.; Hemric, Erin M.; Baker, Paul A.

    2009-12-01

    Late Quaternary climatic and hydrologic variability triggered changes in fluvial deposition and erosion along the course of the Madre de Dios River, Peru, the largest tributary basin of the Madeira basin, itself the largest tributary basin of the Amazon. Three laterally extensive, Quaternary-age, terrace tracts are present within the Madre de Dios basin. Analysis of sedimentary facies, present in the modern cut banks and terraced sequences, along with radiocarbon dates on fossil wood and leaf material preserved in the terraced strata, allow reconstruction of the Late Quaternary depositional history of the sedimentary sequences, including determination of the approximate timing of aggradation and downcutting episodes and its relationship to the timing of past climate change in this portion of the Amazon basin and beyond. The Quaternary sediments underlying the terraces most often recorded deposition in a coarse-grained meandering fluvial system. The T3 terrace, the highest terrace, is underlain by the Miocene (?) Ipururi Formation, which is unconformably overlain by the late Miocene-Pleistocene (?) (> 48,000 cal yrs BP) Madre de Dios Formation, a multistory coarse-sandy to gravelly channel and point bar complex. The latter was downcut before 29,850 ± 100 cal yrs BP. This downcut landscape was infilled by meandering fluvial strata characterized by gravelly channel deposits in a sequence dominated by floodplain and lateral accretion deposits. These strata were in turn downcut to form the T2 terrace before 11,970 ± 100 cal yrs BP. A third episode of aggradation resulted in the deposition of a sand-dominated meandering channel complex that infilled the T2 valley and was subsequently downcut after 3780 ± 50 cal yrs BP. This most recent terrace is infilled by the modern fluvial sediment, which has been actively aggrading since at least 870 ± 50 cal yrs BP. Importantly, the Madre de Dios fluvial system actively aggraded between 30,000 and 25,000 cal yrs BP, (and likely

  13. Transport, Structural and Mechanical Properties of Quaternary FeVTiAl Alloy

    Science.gov (United States)

    Bhat, Tahir Mohiuddin; Gupta, Dinesh C.

    2016-08-01

    The electronic, structural, magnetic and transport properties of FeVTiAl quaternary alloy have been investigated within the framework of density functional theory. The material is a completely spin-polarized half-metallic ferromagnet in its ground state with F-43m structure. The structural stability was further confirmed by elastic constants in the cubic phase with high Young's modulus and brittle nature. The present study predicts an energy band gap of 0.72 eV in a localized minority spin channel at equilibrium lattice parameter of 6.00 Å. The transport properties of the material are discussed based on the Seebeck coefficient, and electrical and thermal conductivity coefficients. The alloy presents large values of Seebeck coefficients, ~39 μV K-1 at room temperature (300 K), and has an excellent thermoelectric performance with ZT = ~0.8.

  14. Synthesis of Tertiary and Quaternary Amine Derivatives from Wood Resin as Chiral NMR Solvating Agents.

    Science.gov (United States)

    Laaksonen, Tiina; Heikkinen, Sami; Wähälä, Kristiina

    2015-01-01

    Chiral tertiary and quaternary amine solvating agents for NMR spectroscopy were synthesized from the wood resin derivative (+)-dehydroabietylamine (2). The resolution of enantiomers of model compounds [Mosher's acid (3) and its n-Bu₄N salt (4)] (guests) by (+)-dehydroabietyl-N,N-dimethylmethanamine (5) and its ten different ammonium salts (hosts) was studied. The best results with 3 were obtained using 5 while with 4 the best enantiomeric resolution was obtained using (+)-dehydroabietyl-N,N-dimethylmethanaminium bis(trifluoromethane-sulfonimide) (6). The compounds 5 and 6 showed a 1:1 complexation behaviour between the host and guest. The capability of 5 and 6 to recognize the enantiomers of various α-substituted carboxylic acids and their n-Bu₄N salts in enantiomeric excess (ee) determinations was demonstrated. A modification of the RES-TOCSY NMR pulse sequence is described, allowing the enhancement of enantiomeric discrimination when the resolution of multiplets is insufficient. PMID:26610454

  15. Synthesis of Tertiary and Quaternary Amine Derivatives from Wood Resin as Chiral NMR Solvating Agents

    Directory of Open Access Journals (Sweden)

    Tiina Laaksonen

    2015-11-01

    Full Text Available Chiral tertiary and quaternary amine solvating agents for NMR spectroscopy were synthesized from the wood resin derivative (+-dehydroabietylamine (2. The resolution of enantiomers of model compounds [Mosher’s acid (3 and its n-Bu4N salt (4] (guests by (+-dehydroabietyl-N,N-dimethylmethanamine (5 and its ten different ammonium salts (hosts was studied. The best results with 3 were obtained using 5 while with 4 the best enantiomeric resolution was obtained using (+-dehydroabietyl-N,N-dimethylmethanaminium bis(trifluoromethane-sulfonimide (6. The compounds 5 and 6 showed a 1:1 complexation behaviour between the host and guest. The capability of 5 and 6 to recognize the enantiomers of various α-substituted carboxylic acids and their n-Bu4N salts in enantiomeric excess (ee determinations was demonstrated. A modification of the RES-TOCSY NMR pulse sequence is described, allowing the enhancement of enantiomeric discrimination when the resolution of multiplets is insufficient.

  16. Terahertz quantum cascade lasers based on quaternary AlInGaAs barriers

    International Nuclear Information System (INIS)

    Terahertz quantum cascade lasers incorporating lattice-matched quaternary AlInGaAs barriers grown by molecular beam epitaxy on InP substrate are reported. Four quantum well active region devices exhibited lasing at 3.8 THz with threshold current densities as low as 74 A/cm2 at 10 K. From optical characterization and a doping study of the active region, an upper state lifetime of 8 ps, as well as a long transport time across the active region of 68 ps and a ratio of free carrier loss to gain cross sections of 4.6%, is reported. A maximum operating temperature of 130 K was achieved for a device with a conduction band discontinuity of 0.14 eV

  17. Geomorphic expression of late Quaternary sea level changes along the southern Saurashtra coast, western India

    Indian Academy of Sciences (India)

    Nilesh Bhatt; Uday Bhonde

    2006-08-01

    Geomorphic expression of land-sea interaction is preserved in the form of abandoned cliffs, marine terraces,shore platforms and marine notches along the southern Saurashtra coast. These features have been used to ascertain the magnitude of sea level changes during late Quaternary.Notch morphology and associated biological encrustation have been used to estimate the magnitude and duration of palaeo-sea strands.Marine notches and other erosive features occurring between 12 and 15 m above the present Biological Mean Sea Level (BMSL) are attributed to the last interglacial corresponding to the Marine Isotopic Stage 5 (MIS-5). However,6 to 9 m upliftment of the coastal fringe is attributed to this sea level.The second major high sea strand was identified during the mid-Holocene when the sea rose 2 m above the present level.Notches corresponding to this high sea level are recorded 4 to 5 m above the present BMSL.

  18. Characterisation of ion transport in sulfonate based ionomer systems containing lithium and quaternary ammonium cations

    International Nuclear Information System (INIS)

    Two sulfonated ionomers based on poly(triethylmethyl ammonium 2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) and containing mixtures of Li+ and quaternary ammonium cations are characterised. The first system contains Li+ and the methyltriethyl ammonium cation (N1222) in a 1:9 molar ratio, and the 7Li NMR line widths showed that the Li+ ions are mobile in this system below the glass transition temperature (105 °C) and are therefore decoupled from the polymer segmental motion. The conductivity in this system was measured as 10−5 S cm−1 at 130 °C. A second PAMPS system containing Li+ and the dimethylbutylmethoxyethyl ammonium cation (N114(2O1)) in a 2:8 molar ratio showed much lower conductivities despite a significantly lower Tg (60 °C), possibly due to associations between the Li+ and the ether group on the ammonium cation, or between the latter cations and the sulfonate groups

  19. A Preliminary Paleomagnetic Rsult of Quaternary Drilling Core form Southern Leizhou Peninsula,Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    王俊达; 梁池生; 等

    1999-01-01

    313 orientated samples were collected from Drilling Core ZK1 in southern Leizhou Peninsula for the study of Quaternary paleomagnetic strato-chronology.Te polarity measurement results indicate that the core recorded paleomagnetic information in three main parts:the upper one of the core,from the ground surface to the depth of 39m ,is normally magnetized in polarity,the middle one,from 39m 59 210m in depth,mainly shows reversed polarity and the lower one recorded normal polarity again.They correspond to the Brunhes normal chron,the Matuyama reversed chron and the Guass normal chron in the geomagnetic polarity time scale,respectively.The age of he core could be over 3.4Ma.Meanwhile,the magnetic susceptibility was measured and its result is significant for stratigraphic division and paleoclimatic research.

  20. Hydrated Electrons in a Quaternary Microemulsion System: A Pulse Radiolysis Study

    Science.gov (United States)

    Adhikari; Joshi; Gopinathan

    1997-07-01

    Using the technique of pulse radiolysis, hydrated electrons have been produced and studied in quaternary microemulsion (sodium lauryl sulfate (NaLS)/water/cyclohexane/1-pentanol) system. Remarkably high lifetimes ( approximately 20 &mgr;s) for hydrated electrons have been obtained. In general, these are two orders of magnitude higher than those reported earlier in reverse micelles. The water droplet sizes and location of the probes have been determined from the decay kinetics of hydrated electrons. The yields and half-lives (t 1/2 ) of the hydrated electrons vary smoothly as the water droplet sizes are changed. We believe that these studies will be useful not only in interpreting electron transfer reactions occurring in small water pockets in biological systems but also in the production of metal nanoclusters by radiation chemical method. PMID:9241228

  1. Controls on Late Quaternary Landscape development in the Upper Guadalentin Basin, Murcia, SE Spain

    International Nuclear Information System (INIS)

    Landscapes in South-eastern Spain have developed in response to tectonics, climatic fluctuations and, more recently, to human action. In the valleys, fluvial colluvial sediments are found in the form of river terraces, pediments and slope deposits. We studied these sediments to evaluate landscape dynamics and the processes of sedimentation and erosion in the semi-arid region of the Guadalentin Basin, Murcia Province, SE Spain. The objective of the study is to deduce controls on Late Quaternary and Holocene landscape development. Fieldwork was carried out on the reach of the Upper Guadalentin, upstream of the city of Lorca, and two of its tributaries (Rio Velez and Rambla de Torrealvilla). River terrace levels were mapped using GPS and presence of gravel layers in outcrops. For the Rambla de Torrealvilla, more detailed sediment descriptions show their build-up. (Author) 18 refs.

  2. Bioaccumulation and tissue distribution of a quaternary ammonium surfactant in three aquatic species

    Energy Technology Data Exchange (ETDEWEB)

    Knezovich, J.P.; Lawton, M.P.; Inouye, L.S.

    1989-01-01

    Quaternary ammonium compounds (QACs) are commonly used as surfactants in drilling muds and fabric softeners and as biocides in antiseptics and disinfectants. QACs and cationic polyelectrolytes elicit acute toxic effects in aquatic organisms by disrupting the structure and function of gill tissues, which may result in the suffocation of the organism. Little information is available, however, on the relative availability and distribution of QACs in the tissues of aquatic organisms. Information of this nature is required to understand the potential consequences of releases of sublethal concentrations of QACs into the aquatic environment. In this study, hexadecylpyridinium bromide (HPB; CAS 140-72-7) was selected as a compound for initial study because it belongs to a chemical class (alkylpyridinium QACs) that includes the most toxic and environmentally persistent QACs. Clams, minnows, and tadpoles were chosen as test organisms to define the relative availability of HPB to organisms that occupy distinctly different ecological niches.

  3. Quaternary tectonics and basin history of Pahrump and Stewart Valleys, Nevada and California

    International Nuclear Information System (INIS)

    The Pahrump fault system is an active fault system located in Pahrump and Stewart Valleys, Nevada and California, in the southern part of the Basin and Range Province. This system is 50 km long by 30 km wide and is comprised of three fault zones: the right-lateral East Nopah fault zone, the right-oblique Pahrump Valley fault zone, and the normal West Spring Mountains fault zone. All three zones have geomorphic evidence for late Quaternary activity. Analysis of active fault patterns and seismic reflection lines suggests that the Pahrump basin has had a two-stage genesis, an early history associated with a period of low angle detachment faulting probably active 10-15 Ma, and a more recent history related to the present dextral shear system, probably active post-4 Ma

  4. Stratigraphic assignment of sample from quaternary age using radiocarbon dating method

    International Nuclear Information System (INIS)

    Radiocarbon dating for quaternary samples from Watuadeg, Kalasan, Sleman Yogyakarta has been carried out. The samples are taken from Tuffaceous sand layer (top sample) which overlies a paleosoil (bottom sample). After pretreatment, the weight of the samples was optimized in order to reach same or more than 20 inHg pressure from CO2 gas or 3 ml volume benzene. The result of the dating of the samples are expected to enable stratigraphic assignment of the layers where the samples were taken. The dating result of the Tuffaceous sand = 5835.69 ± 66.91 BP (3885.69 ± 66.91 BC) and Paleosoil sample = 6127.87± 66.12 BP (4177.87 ± 66.12 BC). From the stratigraphic aspect, the dating results show the two layers, are in conformable relation without any abnormality. (author)

  5. A protocol for subsampling Late Quaternary coprolites for multi-proxy analysis

    Science.gov (United States)

    Wood, Jamie R.; Wilmshurst, Janet M.

    2016-04-01

    The study of Late Quaternary coprolites can provide unique insights into various aspects of the biology and ecology of extinct species and prehistoric humans. Coprolite studies are becoming increasingly multi-disciplinary, allowing a greater amount of information to be obtained from individual specimens. Subsampling is a critical part of multi-proxy coprolite analysis, yet no standardised subsampling protocols exist, and details of subsampling methods have rarely been reported in published studies. Here, we outline a procedure for the subsampling of coprolites for multi-proxy analysis. The method is designed to minimise the risk of sample contamination for sensitive analyses (e.g. ancient DNA, palynology), thereby maximising the robustness of interpretations made from the results. We also stress the need for voucher samples to be retained to ensure the repeatability of results and allow for further analytical methods to be applied to specimens in the future.

  6. Application of DOI index to analysis of selected examples of resistivity imaging models in Quaternary sediments

    Directory of Open Access Journals (Sweden)

    Glazer Michał

    2014-12-01

    Full Text Available Interpretation of resistivity cross sections may be in many cases unreliable due to the presence of artifacts left by the inversion process. One way to avoid erroneous conclusions about geological structure is creation of Depth of Investigation (DOI index maps, which describe durability of prepared model with respect to variable parameters of inversion. To assess the usefulness of this interpretation methodology in resistivity imaging method over quaternary sediments, it has been used to one synthetic data set and three investigation sites. Two of the study areas were placed in the Upper Silesian Industrial District region: Bytom - Karb, Chorzów - Chorzow Stary; and one in the Southern Pomeranian Lake District across Piława River Valley. Basing on the available geological information the results show high utility of DOI index in analysis of received resistivity models, on which areas poorly constrained by data has been designated.

  7. Response to comment on "No late Quaternary strike-slip motion along the northern Karakoram fault"

    Science.gov (United States)

    Robinson, Alexander C.; Owen, Lewis A.; Chen, Jie; Schoenbohm, Lindsay M.; Hedrick, Kathryn A.; Blisniuk, Kimberly; Sharp, Warren D.; Imrecke, Daniel B.; Li, Wenqiao; Yuan, Zhaode; Caffee, Marc W.; Mertz-Kraus, Regina

    2016-06-01

    In their comment on "No late Quaternary strike-slip motion along the northern Karakoram fault", while Chevalier et al. (2016) do not dispute any of the results or interpretations regarding our observations along the main strand of the northern Karakoram fault, they make several arguments as to why they interpret the Kongur Shan Extensional System (KES) to be kinematically linked to the Karakoram fault. These arguments center around how an "active" fault is defined, how slip on segments of the KES may be compatible with dextral shear related to continuation of the Karakoram fault, and suggestions as to how the two fault systems might still be connected. While we appreciate that there are still uncertainties in the regional geology, we address these comments and show that their arguments are inconsistent with all available data, known geologic relationships, and basic kinematics.

  8. Analysis of electrostatic stability and ordering in quaternary perovskite solid solutions

    Science.gov (United States)

    Caetano, Clovis; Butler, Keith T.; Walsh, Aron

    2016-04-01

    There are three distinct classes of perovskite structured metal oxides, defined by the charge states of the cations: AIBVO3,AIIBIVO3 , and AIIIBIIIO3 . We investigated the stability of cubic quaternary solid solutions A B O3-A'B'O3 using a model of point-charge lattices. The mixing enthalpies were calculated and compared for the three possible types of combinations of the compounds, both for the random alloys and the ground-state-ordered configurations. The mixing enthalpy of the (I,V)O3-(III,III)O3 alloy is always larger than the other alloys. We found that, different from homovalent alloys, for these heterovalent alloys a lattice constant mismatch between the constituent compounds could contribute to stabilize the alloy. At low temperatures, the alloys present a tendency to spontaneous ordering, forming superlattices consisting of alternated layers of AB O 3 and A'B'O3 along the [110 ] direction.

  9. Cationic nanoparticles with quaternary ammonium-functionalized PLGA–PEG-based copolymers for potent gene transfection

    International Nuclear Information System (INIS)

    The objective of the present work was to develop new cationic nanoparticles (cNPs) with amphiphilic cationic copolymers for the delivery of plasmid DNA (pDNA). Cationic copolymers were built on the synthesis of quaternary ammonium salt compounds from diethylenetriamine (DETA) to include the positively charged head group and amphiphilic multi-grafts. PLGA-phe-PEG-qDETA (PPD), phe-PEG-qDETA-PLGA (PDP), and PLGA-phe-PEG-qDETA-PLGA (PPDP) cationic copolymers were created by this moiety of DETA quaternary ammonium, heterobifunctional polyethylene glycol (COOH-PEG-NH2), phenylalanine (phe), and poly(lactic-co-glycolic acid) (PLGA). These new cNPs were prepared by the water miscible solvent displacement method. They exhibit good pDNA binding ability, as shown in a retardation assay that occurred at a particle size of ∼217 nm. The zeta potential was approximately +21 mV when the cNP concentration was 25 mg/ml. The new cNPs also have a better buffering capacity than PLGA NPs. However, the pDNA binding ability was demonstrated starting at a weight ratio of approximately 6.25 cNPs/pDNA. Gene transfection results showed that these cNPs had transfection effects similar to those of Lipofectamine 2000 in 293T cells. Furthermore, cNPs can also transfect human adipose-derived stem cells. The results indicate that the newly developed cNP is a promising candidate for a novel gene delivery vehicle

  10. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

    Science.gov (United States)

    Tibaldi, A.; Corazzato, C.; Rovida, A.

    2009-06-01

    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognized four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. The following two events, of Pliocene age, are characterized by lower shortening amounts; they occurred first by reverse faulting with a NW-SE-trending greatest principal stress ( σ1, computed with striated fault planes) and a vertical least principal stress ( σ3), followed by pervasive strike-slip faulting with the same NW-SE-trending σ1 and a horizontal NE-SW σ3. The fourth event, dating to the late Pliocene-Quaternary is characterized by normal faulting: the σ3 still trends NE-SW, whereas the intermediate principal stress σ2 exchanged with σ1. Volcanism accompanied both the contractional, transcurrent and extensional tectonic phases. The Mio-Pliocene compression appears directly linked to a rapid convergence and an apparently important coupling between the continental and oceanic plates. The E-W to WNW-ESE direction of shortening of the Miocene structures and the NW-SE σ1 of the Pliocene structures seem to be more linked to an intra-Andean re-orientation of structures following the WNW-directed absolute motion of the South-American Plate. The extensional deformations can be interpreted as related to gravity forces affecting the highest parts of the volcanic belt in a sort of asymmetrical (SW-ward) collapse of the belt.

  11. Diversification of Southeast Asian mammals during the Quaternary glaciation: insights from the genomic era

    Directory of Open Access Journals (Sweden)

    Lin Miao

    2014-01-01

    Full Text Available Southeast (SE Asia refers to the region east to the Philippine islands, west to the Indian subcontinent, north to central China and south to the Sunda islands. This region includes six of the world’s 25 biodiversity hotspots and is of strategic significance in global biodiversity conservation. The complicated geological and climatological history of this region has resulted in extremely high species diversity and endemism. Two classic biogeographic boundaries, the Wallace Line and the Isthmus of Kra, divide SE Asia into the Indochinese province to the north and Sundaic province to the south. Because the Indochinese and Sundaic provinces are connected today through the Malay Peninsula and the Sunda shelf was exposed for the majority of time during the Quaternary glaciation, previous biogeographic studies have proposed that gene flow occurred between mainland and different island populations causing low divergence in the region. However, recent molecular genetic studies have reported that migration of terrestrial mammal populations was not as great as previously thought due to ecological restrictions. Thus, deep vicariant divergence was present in several mammals as early as two million years ago and appeared not to have been affected by gene flow following the formation of land bridges during later glacial periods. Furthermore, the super eruption of the Toba volcano in Sumatra about 73,000 years ago may have intensified divergence. A literature review has indicated three hierarchical levels present in the formation of mammalian diversity in SE Asia. These include populations between the Indochinese and Sundaic provinces which diverged millions of years ago, populations among the Sunda Islands which diverged hundreds of thousands of years ago, and Late Pleistocene biogeographic events causing demographic changes. Most of the previous population genetic studies on SE Asia mammals were based on analyses of mitochondrial or nuclear DNA data. Recent

  12. External controls on Quaternary fluvial incision and terrace formation at the Segre River, Southern Pyrenees

    Science.gov (United States)

    Stange, Kurt Martin; van Balen, Ronald; Vandenberghe, Jef; Peña, Jose Luis; Sancho, Carlos

    2013-08-01

    Focusing on climatic- and structural (tectonic) controls, we aim to determine their relative importance for the (Pliocene to Quaternary) fluvial landscape evolution in the Southern Pyrenees foreland. We investigate the Segre River, which is one of the major streams of the Southern Pyrenees that drains the elevated chain towards the Ebro foreland basin. Along its course, the Segre River has a flight of fluvial cut-and-fill (and strath-type) terraces preserved that have been mapped based on DEM's and geomorphological fieldwork. This paper presents the first results of our study and reports on the Segre terrace staircase, which is characterized by seven major Quaternary terrace levels with elevations up to more than 110 m above the modern floodplain. At the upper and middle reaches, the semi-parallel terraces of the Segre River occasionally show anomalies featuring extensive gravel thickness and deformation caused by faulting, folding and local subsidence. The longitudinal correlations of terrace levels reveal increased vertical terrace spacing in the foreland, which could originate from enhanced fluvial erosion after the Mid-Pleistocene climate transition in combination with base level lowering controlled by the progressive downcutting of the Catalan Coastal Range. Since the Ebro Basin opening (Late Miocene), the Catalan Coastal Range, which borders the Ebro foreland basin to the Mediterranean Sea, was progressively cut down and the exorheic drainage system gradually adjusted to sea level. The Segre longitudinal terrace profiles and the Ebro gorge morphology at the Catalan Coastal Range indicate a base-level of about 200 m.s.l. at the beginning of (Pleistocene) terrace formation, which implies that the Catalan Coastal Range might have functioned as a local base-level upstream of the sea outlet, presumably until the Late Pleistocene. Alternatively, a yet unknown tectonic process might have caused base level lowering and the preservation of terrace staircases at the

  13. Deconstructing mammal dispersals and faunal dynamics in SW Europe during the Quaternary

    Science.gov (United States)

    Palombo, Maria Rita

    2014-07-01

    This research aims to investigate the relationships between climate change and faunal dynamics in south-west Europe, disentangling the asynchronous and diachronous dispersal bioevents of large mammals across geographical and ecological boundaries, analysing biodiversity and its changes through time. The analysis of local versus regional biological dynamics may shed new light on whether turnovers and ecological and evolutionary changes developed because of global climate changes and related phenomena, or because of intrinsic biological factors. The SW European Quaternary fossil record is particularly suitable for studying the role of climate change at local and regional levels because of the complex physiographic and climatic heterogeneity of the study area, the presence of important geographical/ecological barriers and the complex history of invasions of species of varying geographical origin and provenance. The data base consists of taxonomically revised lists of large mammal species from selected SW European local faunal assemblages ranging in age from the Early to the late Middle Pleistocene (middle Villafranchian to early Aurelian European Land Mammal Ages). The new biochronological scheme proposed here allows for the comparison of local turnovers and biodiversity trends, yielding a better understanding of the action of geographical/ecological barriers that either prevented the range of some taxa from reaching some regions or caused delays in the dispersal of a taxon in some territories. The results obtained provide evidence that major environmental perturbations, triggering dispersal events and removing keystone species, modified the structure of the pre-existing mammalian faunas, merging previously independently-evolved taxa into new palaeo-communities. The coupled action of climatic changes and internal biotic dynamics thus caused the Quaternary SW European faunal complexes to significantly restructure. Diachroneity in local turnover across the study area

  14. Initial Insights into the Quaternary Evolution of the Laurentide Ice Sheet on Southeastern Baffin Island

    Science.gov (United States)

    Pendleton, S.; Anderson, R. S.; Miller, G. H.; Refsnider, K. A.

    2015-12-01

    Increasing Arctic summer temperatures in recent decades and shrinking cold-based ice caps on Cumberland Peninsula, Baffin Island, are exposing ancient landscapes complete with uneroded bedrock surfaces. Previous work has indicated that these upland surfaces covered with cold-based ice experience negligible erosion compared with the valleys and fjords systems that contain fast-flowing ice. Given the appearance of highly weathered bedrock, it is argued that these landscapes have remained largely unchanged since at least the last interglaciation (~120 ka), and have likely experienced multiple cycles of ice expansion and retraction with little erosion throughout the Quaternary. To explore this hypothesis, we use multiple cosmogenic radionuclides (26Al and 10Be) to investigate and provide insight into longer-term cryosphere activity and landscape evolution. 26Al/10Be in surfaces recently exposed exhibit a wide range of exposure-burial histories. Total exposure-burial times range from ~0.3 - 1.5 My and estimated erosion rates from 0.5 - 6.2 m Ma-1. The upland surfaces of the Penny Ice cap generally experienced higher erosion rates (~0.45 cm ka-1) than those covered by smaller ice caps (~0.2 cm ka-1). The cumulative burial/exposure histories in high, fjord-edge locations indicate that significant erosion north of the Penny Ice Cap ceased between ~600 and 800 ka, suggesting that Laurentide Ice Sheet (LIS) organization and fjord inception was underway by at least this time. Additionally, 26Al/10Be ratios near production values despite high inventories from a coastal summit 50 km east of the Penny Ice Cape suggest that that area has not experienced appreciable burial by ice, suggesting that it was never inundated by the LIS. Moreover, these initial data suggest a variable and dynamic cryosphere in the region and provide insight into how large ice sheets evolved and organized themselves during the Quaternary.

  15. Agricultural contaminants in Quaternary aquitards: A review of occurrence and fate in North America

    Science.gov (United States)

    Rodvang, S. J.; Simpkins, W. W.

    2001-01-01

    The intensity of agriculture has increased significantly during the past 30 years, resulting in increased detection of agricultural contaminants (nutrients, pesticides, salts, trace elements, and pathogens) in groundwater. Till, glaciolacustrine, and loess deposits of Quaternary age compose the most common surficial deposits underlying agricultural areas in North America. Quaternary aquitards generally contain higher concentrations of solid organic carbon (SOC, as much as 1.4%), dissolved organic carbon (DOC, as much as 205 mg/L), and reduced sulfur (as much as 0.9%) than do aquifers. Their potential to sorb pesticides increases with the percent of older SOC, because diagenesis increases Koc. Denitrification consistently reduces nitrate to non-detectable levels in unweathered Quaternary aquitards. Organic carbon of Quaternary age is a more labile electron donor than carbon from shale clasts. Pyrite is a more labile electron donor than carbon in many instances. Unweathered Quaternary aquitards provide a high degree of protection for underlying aquifers, due to their large reserves of SOC and reduced sulfur for sorption and denitrification, combined with their typically low hydraulic conductivity. In contrast, agricultural contaminants are common in weathered Quaternary aquitards. Lower reserves of reduced sulfur and sorptive/labile organic carbon, and a higher bulk K due to fractures, limit their ability to attenuate nitrate and pesticides. Subsurface drainage, which is common in Quaternary aquitards because of high water tables, bypasses the attenuation capacity of Quaternary aquitards and facilitates the transport of agricultural contaminants to surface water. Résumé. L'agriculture s'est significativement accrue au cours des dernières 30 années, provoquant une détection plus fréquente dans les eaux souterraines de contaminants agricoles (engrais, pesticides, sels, éléments en traces et germes pathogènes). Les moraines, les formations glacio-lacustres et

  16. Late Quaternary distribution dynamics and phylogeography of the red deer ( Cervus elaphus) in Europe

    Science.gov (United States)

    Sommer, R. S.; Zachos, F. E.; Street, M.; Jöris, O.; Skog, A.; Benecke, N.

    2008-04-01

    Here we present spatial-temporal patterns for European late Quaternary red deer (Cervus elaphus), based on radiocarbon-supported evidence derived mainly from archaeological sites. This is followed by an overview of the recent phylogeography of this species using haplogroup studies of recent molecular data. The implications of the synthesis of palaeontological and genetic data are discussed and we propose that present day European red deer haplogroup distributions are best explained against the history of late Quaternary population contractions into and expansions from glacial refugia. Around 800 records of Cervus elaphus were assigned to the period covering the later part of the Last Glacial and the Early to Middle Holocene. Red deer becomes increasingly visible in faunal assemblages dated to late OIS-3 (<40.0 ka 14C BP). The species persisted throughout the LGM on the Iberian Peninsula, in adjacent regions of South-Western France (Gascony, Dordogne, Languedoc), on the Italian Peninsula, in the Balkans and Greece, and east of the Carpathians in Moldavia. We suggest that genetic exchange between the populations of the Balkans and the East of the Carpathians remained uninterrupted during the LGM. The expansion of red deer from its southern refugia into Central and Northern Europe begins rapidly at 12,500 14C BP. The expansion of red deer coincides with the sudden rise in temperature at the onset of Greenland Interstadial 1e and the dispersion of open birch woodland into the northern half of Europe. Radiocarbon supported records show a more or less universal distribution of Cervus elaphus across Europe following the Pleistocene/Holocene climatic change at 10.0 ka 14C BP for the first time. Molecular data and fossil record combined provide a clearer temporal and spatial pattern for the Lateglacial recolonisation process of the northern part of Europe.

  17. Micromorphological investigations of the Late Quaternary loess-paleosol sequences of the Kashmir Valley, India

    Science.gov (United States)

    Dar, Reyaz Ahmad; Chandra, Rakesh; Romshoo, Shakil Ahmad; Kowser, Nazia

    2015-11-01

    The loess-paleosol sequences of the Karewa Group preserve a valuable repository of the Late Quaternary climatic changes and the landscape evolution history of the Karewa Basin of Kashmir Valley in their lithological and pedogenic records. Three representative loess-paleosol sections at Shankerpora (SP), Khan Sahib (KS) and Pattan (PT) localities were chosen for detailed lithostratigraphic fieldwork and micromorphological observations of thin sections. Lithostratigraphic analysis revealed lateral and vertical variation in thickness and number of paleosol profiles from south-west to north-west of the Karewa Basin suggesting the availability of land-surface for periodic loess deposition. The SP section is marked by 6 (SP-S6, S7, S8, S9, S10, S12), KS section by 3 (KS-S2, S4, S5) and PT section by 2 (PT-S1, S3) thick mature paleosol profiles. Theses paleosols have well developed 'Ah' and 'Btk' horizons representing prolonged land-surface stability when pedogenic processes outpace loess deposition. On the other hand comparatively thin to thick paleosol profiles represent weak to moderate pedogenic maturity indicating short stratigraphic breaks with rapid loess deposition. Micromorphological observations of thin sections suggested that clay illuviation and CaCO3 accumulation have operated within the paleosol profiles. CaCO3 features are often associated with clay coatings suggesting decalcification of carbonates followed by clay illuviation. Pedogenic CaCO3 probably resulted from the precipitation of the soil solution near the average depth of wetting front. The pedogenic CaCO3, illuvial clay, mottles, iron manganese features, pedal microstructure and blocky aggregates reveal variation in the pedogenic maturity among and within the loess-paleosol sections. The morphological (both micro- and macro-morphological) attributes of loess-paleosols suggest variation of climatic conditions during the Late Quaternary period in the Karewa Basin of Kashmir Valley, India.

  18. Phylogeography of Rhodiola kirilowii (Crassulaceae: a story of Miocene divergence and quaternary expansion.

    Directory of Open Access Journals (Sweden)

    Jian-Qiang Zhang

    Full Text Available The evolution and current distribution of the Sino-Tibetan flora have been greatly affected by historical geological events, such as the uplift of the Qinghai-Tibetan Plateau (QTP, and Quaternary climatic oscillations. Rhodiola kirilowii, a perennial herb with its distribution ranging from the southeastern QTP and the Hengduan Mountains (HM to adjacent northern China and central Asia, provides an excellent model to examine and disentangle the effect of both geological orogeny and climatic oscillation on the evolutionary history of species with such distribution patterns. We here conducted a phylogeographic study using sequences of two chloroplast fragments (trnL-F and trnS-G and internal transcribed spacers in 29 populations of R. kirilowii. A total of 25 plastid haplotypes and 12 ITS ribotypes were found. Molecular clock estimation revealed deep divergence between the central Asian populations and other populations from the HM and northern China; this split occurred ca. 2.84 million year ago. The majority of populations from the mountains of northern China were dominated by a single haplotype or ribotype, while populations of the HM harbored both high genetic diversity and high haplotype diversity. This distribution pattern indicates that HM was either a diversification center or a refugium for R. kirilowii during the Quaternary climatic oscillations. The present distribution of this species on mountains in northern China may have resulted from a rapid glacial population expansion from the HM. This expansion was confirmed by the mismatch distribution analysis and negative Tajima's D and Fu's FS values, and was dated to ca. 168 thousand years ago. High genetic diversity and population differentiation in both plastid and ITS sequences were revealed; these imply restricted gene flow between populations. A distinct isolation-by-distance pattern was suggested by the Mantel test. Our results show that in old lineages, populations may harbour

  19. Human Antibodies that Recognize Novel Immunodominant Quaternary Epitopes on the HIV-1 Env Protein.

    Directory of Open Access Journals (Sweden)

    Mark D Hicar

    Full Text Available Numerous broadly neutralizing antibodies (Abs target epitopes that are formed or enhanced during mature HIV envelope formation (i.e. quaternary epitopes. Generally, it is thought that Env epitopes that induce broadly neutralizing Abs are difficult to access and poorly immunogenic because of the characteristic oligomerization, conformational flexibility, sequence diversity and extensive glycosylation of Env protein. To enhance for isolation of quaternary epitope-targeting Abs (QtAbs, we previously used HIV virus-like particles (VLPs to bind B cells from long-term non-progressor subjects to identify a panel of monoclonal Abs. When expressed as recombinant full-length Abs, a subset of these novel Abs exhibited the binding profiles of QtAbs, as they either failed to bind to monomeric Env protein or showed much higher affinity for Env trimers and VLPs. These QtAbs represented a significant proportion of the B-cell response identified with VLPs. The Ab genes of these clones were highly mutated, but they did not neutralize common HIV strains. We sought to further define the epitopes targeted by these QtAbs. Competition-binding and mapping studies revealed these Abs targeted four separate epitopes; they also failed to compete for binding by Abs to known major neutralizing epitopes. Detailed epitope mapping studies revealed that two of the four epitopes were located in the gp41 subunit of Env. These QtAbs bound pre-fusion forms of antigen and showed differential binding kinetics depending on whether oligomers were produced as recombinant gp140 trimers or as full-length Env incorporated into VLPs. Antigenic regions within gp41 present unexpectedly diverse structural epitopes, including these QtAb epitopes, which may be targeted by the naturally occurring Ab response to HIV infection.

  20. Human Antibodies that Recognize Novel Immunodominant Quaternary Epitopes on the HIV-1 Env Protein.

    Science.gov (United States)

    Hicar, Mark D; Chen, Xuemin; Sulli, Chidananda; Barnes, Trevor; Goodman, Jason; Sojar, Hakimuddin; Briney, Bryan; Willis, Jordan; Chukwuma, Valentine U; Kalams, Spyros A; Doranz, Benjamin J; Spearman, Paul; Crowe, James E

    2016-01-01

    Numerous broadly neutralizing antibodies (Abs) target epitopes that are formed or enhanced during mature HIV envelope formation (i.e. quaternary epitopes). Generally, it is thought that Env epitopes that induce broadly neutralizing Abs are difficult to access and poorly immunogenic because of the characteristic oligomerization, conformational flexibility, sequence diversity and extensive glycosylation of Env protein. To enhance for isolation of quaternary epitope-targeting Abs (QtAbs), we previously used HIV virus-like particles (VLPs) to bind B cells from long-term non-progressor subjects to identify a panel of monoclonal Abs. When expressed as recombinant full-length Abs, a subset of these novel Abs exhibited the binding profiles of QtAbs, as they either failed to bind to monomeric Env protein or showed much higher affinity for Env trimers and VLPs. These QtAbs represented a significant proportion of the B-cell response identified with VLPs. The Ab genes of these clones were highly mutated, but they did not neutralize common HIV strains. We sought to further define the epitopes targeted by these QtAbs. Competition-binding and mapping studies revealed these Abs targeted four separate epitopes; they also failed to compete for binding by Abs to known major neutralizing epitopes. Detailed epitope mapping studies revealed that two of the four epitopes were located in the gp41 subunit of Env. These QtAbs bound pre-fusion forms of antigen and showed differential binding kinetics depending on whether oligomers were produced as recombinant gp140 trimers or as full-length Env incorporated into VLPs. Antigenic regions within gp41 present unexpectedly diverse structural epitopes, including these QtAb epitopes, which may be targeted by the naturally occurring Ab response to HIV infection. PMID:27411063

  1. Supramolecular assembly of borate with quaternary ammonium: Crystal structure and tunable luminescent properties

    International Nuclear Information System (INIS)

    A new borate [C6H16N][B5O6(OH)4] (1) is synthesized hydrothermally by the reaction of isopropyltrimethylammonium hydroxide with boric acid. It crystallizes in the triclinic space group P-1 with the parameters a=9.1578(10) Å, b=9.372(9) Å, c=9.9812(10) Å, α=66.508(2)°, β=74.751(2)°, γ=81.893(2)°. The [B5O6(OH)4]− anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH3)3(i-C3H7) N+ cations. This borate shows tunable luminescent properties with temperature, heating-treatment, exciting-light, and solvents. The fluorescent intensity of 1 enhances 6-fold with decreasing the temperature from 25 K to 78 K. By treatment under different temperatures, the luminescence of 1 shifted from blue to white and the sample treated at 230 °C emits bright white light to naked eyes. The hybrid borate can disperse in different solvents, and shows a red-shifted and intense emission in polar solvents. - Graphical abstract: The new quaternary ammonium borate [C6H17N][B5O6(OH)4] contains a 3D supramolecular network formed by hydrogen bond linked [B5O6(OH)4]− anions and shows tunable luminescent properties with temperature, excitation light, and solvents. Highlights: ► A novel quaternary ammonium borate was synthesized. ► It possesses a supramolecular network fomed by H-bonded [B5O6(OH)4]− anions. ► This borate shows tunable luminescent properties with temperature, heating treatment, excitation light, and solvents

  2. Evidence for Quaternary earthquakes from paleo-fluidization structures along the Pernambuco lineament (NE-Brazil).

    Science.gov (United States)

    Nestola, Yago; Balsamo, Fabrizio; Hilario Rego Bezerra, Francisco; Cézar Costa Nogueira, Fancisco; Storti, Fabrizio

    2014-05-01

    Plate tectonics theory postulate that seismicity is mostly restricted to the plate's boundaries. Nevertheless, intraplate earthquakes occur in stable continental areas such as the NE-Brazilian craton, where seismicity is clustered along fault systems reactivating major Neoproterozoic shear zones. Moreover, evidence for tectonic activity is recorded in the Cenozoic post-rift formations, widely outcropping along the coast of the NE-Brazilian passive margin. To investigate such unexpected seismic and tectonic activity we performed a structural field survey along the coastal segment of the Pernambuco shear zone, where the Miocene sandstone of the Barreiras Fm. and the overlying Quaternary post-Barreiras deposits extensively crop out. They are separated by a Tortonian lateritic paleosoil and are affected by mainly extensional faulting, associated with some strike-slip deformation, clustered in N-S, WNW-ESE, and NE-SW trends. In the proximity of the Pernambuco shear zone, in the hinterland of the Recife town, we found evidence for paleo-fluidization structures in post-Barreiras deposits, where mobilized materials include cm-dm-sized, heterogeneous angular clasts in a sandy-dominated matrix. The extent of the exposed fluidized bodies exceeds ~50 m in active quarry walls, the maximum thickness reaches ~3 m, and the depth of fluidization is estimated to be about 30 m. The top seal of fluidized material was provided by a ~80 cm thick clay layer. Such fluidizations are located few hundreds meters far from a major NE-SW-trending, sin-sedimentary extensional fault zone developed in Quaternary deposits, which is consistent with a left-lateral strike-slip sense of shear of the Pernambuco shear zone. Our results further improve the knowledge of paleo-seismic activity along the Pernambuco shear zone and, in particular, provide additional information for the seismic hazard assessment in the high-density populated area of the Recife town.

  3. Quaternary ammonium as vector of radioisotopes toward cartilage proteoglycans: in vivo imaging and monitoring of chondrosarcoma

    International Nuclear Information System (INIS)

    The full text of the publication follows. AIM: Our strategy consists in using the quaternary ammonium function, that exhibits a high affinity for proteoglycans, as a selective carrier to cartilage of (i) drugs for improving the selectivity or (ii) radioisotopes for imaging and evaluating response to treatment. For diagnosis, a radiotracer radiolabeled with 99mTc (99mTc-NTP 15-5) was selected and for therapeutic application, a quaternary ammonium derivative of melphalan (Mel-AQ) was synthesized. This study demonstrates the interest of this strategy for the diagnosis and treatment of chondrosarcoma. Methods: 99mTc-NTP 15-5 imaging was performed at regular intervals in rats bearing ortho-topic swarm chondrosarcoma, controls or treated (Mel-AQ: three intravenous doses of 10 mg/kg). 99mTc-HMDP imaging (the only radiotracer available for nuclear medicine diagnosis of chondrosarcoma) was also performed. Results: All rats exhibited a significant tumoral uptake of 99mTc-NTP 15-5 at very early stage of pathology while no palpable nor measurable tumour could be assessed. Furthermore, tumoral uptake increased as pathology progressed over time. When animals were treated with Mel-AQ, a significant tumor growth inhibition was observed with 99mTc-NTP 15-5 tumoral uptake being significantly decreased as compared to controls. 99mTc-HMDP bone scans were negative during the whole study. Conclusion: These experimental results underline (i) the potential of the proteoglycan targeting strategy for the early and specific diagnosis imaging of chondrosarcoma and its response to therapy and (ii) the efficiency of the targeted anti-tumoral therapy. In future, we could plan to substitute technetium atom for copper atom for radionuclide therapy application. Grants: INCa, CPER, Ligue contre le cancer, FRI/OSEO. (authors)

  4. Order and disorder in quaternary atomic laminates from first-principles calculations.

    Science.gov (United States)

    Dahlqvist, Martin; Rosen, Johanna

    2015-12-21

    We report on the phase stability of chemically ordered and disordered quaternary MAX phases - TiMAlC, TiM2AlC2, MTi2AlC2, and Ti2M2AlC3 where M = Zr, Hf (group IV), M = V, Nb, Ta (group V), and M = Cr, Mo, W (group VI). At 0 K, layered chemically ordered structures are predicted to be stable for M from groups V and VI. By taking into account the configurational entropy, an order-disorder temperature Tdisorder can be estimated. TiM2AlC2 (M = Cr, Mo, W) and Ti2M2AlC3 (M = Mo, W) are found with Tdisorder > 1773 K and are hence predicted to be ordered at the typical bulk synthesis temperature of 1773 K. Other ordered phases, even though metastable at elevated temperatures, may be synthesized by non-equilibrium methods such as thin film growth. Furthermore, phases predicted not to be stable in any form at 0 K can be stabilized at higher temperatures in a disordered form, being the case for group IV, for MTi2AlC2 (M = V, Cr, Mo), and for Ti2M2AlC3 (M = V, Ta). The stability of the layered ordered structures with M from group VI can primarily be explained by Ti breaking the energetically unfavorable stacking of M and C where M is surrounded by C in a face-centered cubic configuration, and by M having a larger electronegativity than Al resulting in a fewer electrons available for populating antibonding Al-Al orbitals. The results show that these chemically ordered quaternary MAX phases allow for new elemental combinations in MAX phases, which can be used to add new properties to this family of atomic laminates and in turn prospects for tuning these properties. PMID:26565395

  5. Quaternary deformation associated with the Tripoli-Roum Thrust, and the rise of the lebanese coast.

    Science.gov (United States)

    Elias, A.; Tapponnier, P.; Jacques, E.; Daëron, M.; Klinger, Y.; Sursock, A.

    2003-04-01

    The Tripoli-Roum Thrust, which is part of the Levant Fault zone, appears to take up most of the shortening perpendicular to the Yammuneh Fault, thus producing the rise of Mount Lebanon since the late Neogene. In northern Lebanon, there is clear field evidence of active and recent folding and faulting along this thrust system. Three principal faults, oriented ~NNE-SSW, cut through the recent topography north of Tripoli. These oblique right-lateral strike-slip thrust ramps deform Neogene (Vindobonian to Astian) and Quaternary sedimentary and volcanic beds. The northernmost ramp is responsible for the growth of the young, asymmetric, Borj-el-Arab anticline, which folds Quaternary beachrocks and conglomerates, and reaches the Mediterranean coastline near Aabdé. This feature (thrust and ramp-anticline) continues offshore Tripoli, north of the Palmier and Rankine islands, and is probably responsible for the asymmetric uplift of shorelines and marine-cut terraces topping the islands. Active reverse faulting along the Tripoli-Roum thrust at sea appears to be also responsible for the rise of the many paleo-seacliffs and marine terraces found up to 500m asl along the Lebanese coast between Aabdé in the North and Saida in the South. Near Tabarja, and in the islands offshore Tripoli, we interpret the lowest uplifted marine terraces and double shoreline "trottoirs" identified and mapped by P. Sanlaville, to result from recurrent coseismic uplift during two or three seismic events on the offshore thrust. The last of these events was probably that which destroyed Beyrouth in 551A.D. Shell datings of the uplifted trottoirs yield 0,5 to 0,7 mm/yr as a first estimate of the uplift rate, relative to sea level, of the hanging wall of the Tripoli-Roum thrust ramp.

  6. Cationic nanoparticles with quaternary ammonium-functionalized PLGA–PEG-based copolymers for potent gene transfection

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan-Hsung [Kaohsiung Medical University, School of Dentistry, College of Dental Medicine (China); Fu, Yin-Chih [Kaohsiung Medical University, Graduate Institute of Medicine, College of Medicine (China); Chiu, Hui-Chi [Kaohsiung Medical University, Department of Medicinal and Applied Chemistry, College of Life Science (China); Wang, Chau-Zen [Kaohsiung Medical University, Department of Physiology, College of Medicine (China); Lo, Shao-Ping [Kaohsiung Medical University, Department of Medicinal and Applied Chemistry, College of Life Science (China); Ho, Mei-Ling [Kaohsiung Medical University, Department of Physiology, College of Medicine (China); Liu, Po-Len [Kaohsiung Medical University, Department of Respiratory Therapy, College of Medicine (China); Wang, Chih-Kuang, E-mail: ckwang@kmu.edu.tw [Kaohsiung Medical University, Department of Medicinal and Applied Chemistry, College of Life Science (China)

    2013-11-15

    The objective of the present work was to develop new cationic nanoparticles (cNPs) with amphiphilic cationic copolymers for the delivery of plasmid DNA (pDNA). Cationic copolymers were built on the synthesis of quaternary ammonium salt compounds from diethylenetriamine (DETA) to include the positively charged head group and amphiphilic multi-grafts. PLGA-phe-PEG-qDETA (PPD), phe-PEG-qDETA-PLGA (PDP), and PLGA-phe-PEG-qDETA-PLGA (PPDP) cationic copolymers were created by this moiety of DETA quaternary ammonium, heterobifunctional polyethylene glycol (COOH-PEG-NH{sub 2}), phenylalanine (phe), and poly(lactic-co-glycolic acid) (PLGA). These new cNPs were prepared by the water miscible solvent displacement method. They exhibit good pDNA binding ability, as shown in a retardation assay that occurred at a particle size of ∼217 nm. The zeta potential was approximately +21 mV when the cNP concentration was 25 mg/ml. The new cNPs also have a better buffering capacity than PLGA NPs. However, the pDNA binding ability was demonstrated starting at a weight ratio of approximately 6.25 cNPs/pDNA. Gene transfection results showed that these cNPs had transfection effects similar to those of Lipofectamine 2000 in 293T cells. Furthermore, cNPs can also transfect human adipose-derived stem cells. The results indicate that the newly developed cNP is a promising candidate for a novel gene delivery vehicle.

  7. Preliminary results of paleoseismic investigations of Quaternary faults on eastern Yucca Mountain, Nye County, Nevada

    International Nuclear Information System (INIS)

    Site characterization of the potential nuclear waste repository at Yucca Mountain, Nevada, requires detailed knowledge of the displacement histories of nearby Quaternary faults. Ongoing paleoseismic studies provide data on the amount and rates of Quaternary activity on the Paintbrush Canyon, Bow Ridge, and Stagecoach Road faults along the eastern margin of the mountain over varying time spans of 0-700 ka to perhaps 0-30 ka, depending on the site. Preliminary stratigraphic interpretations of deposits and deformation at many logged trenches and natural exposures indicate that each of these faults have experienced from 3 to 8 surface-rupturing earthquakes associated with variable dip-slip displacements per event ranging from 5 to 115 cm, and commonly in the range of 20 to 85 cm. Cumulative dip-slip offsets of units with broadly assigned ages of 100-200 ka are typically less than 200 cm, although accounting for the effects of possible left normal-oblique slip could increase these displacements by factors of 1.1 to 1.7. Current age constraints indicate recurrence intervals of 104 to 105 years (commonly between 30 and 80 k.y.) and slip rates of 0.001 to 0.08 mm/yr (typically 0.01-0.02 mm/yr). Based on available timing data, the ages of the most recent ruptures varies among the faults; they appear younger on the Stagecoach Road Fault (∼5-20 ka) relative to the southern Paintbrush Canyon and Bow Ridge faults (∼30-100 ka)

  8. Electronic band structure of quaternary alloy Zn{sub y}Cd{sub 1-y}Se{sub x}Te{sub 1-x}

    Energy Technology Data Exchange (ETDEWEB)

    Benkabou, K. [Physics Department, Laboratory of Applied Materials, University of Sidi Bel Abbes (Algeria)], E-mail: kbenkabou@yahoo.fr; Amrane, N.; Maachou, M. [Physics Department, Laboratory of Applied Materials, University of Sidi Bel Abbes (Algeria)

    2008-10-06

    A tight binding formalism within virtual crystal approximation in which, the effects of composition disorder and bonds relaxation are involved, is applied to the quaternary system Zn{sub y}Cd{sub 1-y}Se{sub x}Te{sub 1-x} so as to compute its energy band gap and predict the ionic character. A new model, calculating the relaxation of bonds for the quaternary alloys is presented. The electronic parameters of the quaternary alloy considered are calculated as function of x composition. Very good agreement is obtained between the available experimental data and our results.

  9. Synthesis and Spectroscopic Characterisation of 2,3-Epoxy/3-Chloro-2-hydroxy Propyl Derivatives of Quaternary Ammonium Salts: Useful Cationic Fixing Agents

    Institute of Scientific and Technical Information of China (English)

    SHARIF Saima; AHMAD Saeed; IZHAR-UL-HAQ Mian Muhammad

    2008-01-01

    Eight mono-reactive and four bis-reactive 2,3-epoxy/3-chloro-2-hydroxy propyl derivatives of quaternary ammonium salts have been synthesised by reacting epichlorohydrin with suitable tertiary amines and diamines.Mono-reactive derivatives also contain cyano and carboxylic groups in addition to 2,3-epoxy/3-chloro-2-hydroxy propyl groups. The structures of these quaternary ammonium salts have been characterised using IR and 1H NMR spectroscopic techniques. These quaternary ammonium chlorides have been applied to the cotton fabrics as pretreatments and aftertreatments and promising results have been obtained.

  10. Beta particles sensitivity of an all-carbon detector

    International Nuclear Information System (INIS)

    The response of high quality polycrystalline diamond pixel detectors to 90Sr beta particles is reported. Laser induced surface graphitization was used to realize 36 conductive contacts with 1 mm×1 mm area each, pitch 1.2 mm, on one detector side whereas a 8 mm×8 mm large area graphite contact was realized on the other face for grounding or biasing. A proximity board was used to hold the matrix, the amplifiers and to bond nine pixels to test homogeneity of response among 36 detector pixels. Two configurations were used to test charge collection uniformity and signal dependence on voltage. Both configurations showed noise pedestal fitted with a Gaussian curve of 1150 equivalent electrons (1σ) and typical beta source particles spectrum. Reversing the bias polarity the pulse height distribution does not change and the saturation of most probable value of charge collection was observed around ±200 V (0.4 V/μm) with reasonable pixel response uniformity equal to a most probable value 1.28±0.05 fC. The charge collection efficiency (CCE) measurement was implemented using coincidence mode acquisition with an external trigger made by a commercial polycrystalline diamond slab. The detector shows a CCE=0.59 estimated using the 1 mm2 large graphite pixel. The information earned with this first prototype will be used to design the new board with amplifying electronics for reading all 36 pixels at a time and perform experiments with monochromatic high energy electrons

  11. Los Angeles Seismotectonics: Evidence from Shotgun Seismicity Patterns and the Gridlock of Late Quaternary Faults and Folds

    Science.gov (United States)

    Hauksson, E.; Michael, A.

    2001-12-01

    The high tectonic strain rates in the Los Angeles region are caused by the San Andreas fault to the north that strikes more westerly than the relative plate motion velocity, and secondary effects such as basin formation, and possibly the upper mantle drip beneath the Transverse Ranges. The last 25 years of background seismicity in this region is spatially scattered and cannot easily be associated with the complex network of existing late Quaternary faults or folds. To explain the regionally distributed seismicity and faulting patterns we propose the following model of seismotectonic deformation for the Los Angeles region. First, the regional tectonic strain loading is spread almost uniformly from east to west across the region, causing only minor variations in the loading rate of late Quaternary faults. Second, these late Quaternary faults that have cumulative offsets of at least few kilometers are aseismic during the interseismic period and only accommodate large earthquakes. Third, most of the late Quaternary faults have similar slip rate and are of similar importance for accommodating crustal deformation, and thus have similar repeat times for large earthquakes. Fourth, the background seismicity mostly accommodates secondary deformation associated with geometrical complexities of existing geological structures. In a few cases the background seismicity however, forms halos around the faults suggesting narrow central locked fault zones and an adjacent seismic zone of ongoing buildup of tectonic strain. To refine these patterns of seismicity we have relocated the last 25 years of Los Angeles seismicity using double-difference earthquake location methods to refine hypocenters based on three-dimensional velocity models to obtain high-resolution hypocenters. These DD hypocenters provide improved resolution of seismicity patterns and facilitate improved association between seismicity and late Quaternary faults and active geological structures. The background seismicity

  12. Estimated Altitude of the Consolidated Rock Surface Underlying Quaternary Sediments of the Wood River Valley aquifer system, South-Central Idaho

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset is the estimated altitude of the consolidated rock surface underlying Quaternary sediment of the Wood River Valley aquifer system. This surface is...

  13. Study of the influence of pre-activation of vermiculite and concentration of the quaternary ammonium salt in obtaining of organovermiculita

    International Nuclear Information System (INIS)

    Organoclays, are derived from the addition of quaternary ammonium salts in aqueous dispersions of natural clays or sodium. The aim of this study was to obtain organoclays from the intercalation of clay mineral vermiculite and quaternary ammonium salt Praepagem WB, thus, was used to study the concentrations of salt activation of Na2CO3, the cure time of this salt and varying the concentration the quaternary ammonium salt. The X-ray diffraction was used to determine whether there was a change in basal spacing after intercalation process with the quaternary ammonium salt. The process of organophilization of vermiculite, was confirmed by change in clay basal interplanar distance, which was 14.32 Å and after the addition of salt increased to 60.04 Å when activated for 5 days. (author)

  14. Quaternary isobaric (vapor + liquid + liquid) equilibrium and (vapor + liquid) equilibrium for the system (water + ethanol + cyclohexane + heptane) at 101.3 kPa

    International Nuclear Information System (INIS)

    Highlights: → Water-ethanol-cyclohexane-heptane and water-cyclohexane-heptane isobaric VLLE. → Isobaric experimental data were determined at 101.3 kPa. → A dynamic recirculating still with an ultrasonic homogenizer was used. → The quaternary system does not present quaternary azeotropes. - Abstract: Experimental isobaric (vapor + liquid + liquid) and (vapor + liquid) equilibrium data for the ternary system {water (1) + cyclohexane (2) + heptane (3)} and the quaternary system {water (1) + ethanol (2) + cyclohexane (3) + heptane (4)} were measured at 101.3 kPa. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer was used to determine the VLLE. The results obtained show that the system does not present quaternary azeotropes. The point-by-point method by Wisniak for testing the thermodynamic consistency of isobaric measurements was used to test the equilibrium data.

  15. Quaternary isobaric (vapor + liquid + liquid) equilibrium and (vapor + liquid) equilibrium for the system (water + ethanol + cyclohexane + heptane) at 101.3 kPa

    Energy Technology Data Exchange (ETDEWEB)

    Pequenin, Ana; Asensi, Juan Carlos [Departamento de Ingenieria Quimica, Universidad de Alicante, Ap. 99, E-03080 Alicante (Spain); Gomis, Vicente, E-mail: vgomis@ua.es [Departamento de Ingenieria Quimica, Universidad de Alicante, Ap. 99, E-03080 Alicante (Spain)

    2011-08-15

    Highlights: > Water-ethanol-cyclohexane-heptane and water-cyclohexane-heptane isobaric VLLE. > Isobaric experimental data were determined at 101.3 kPa. > A dynamic recirculating still with an ultrasonic homogenizer was used. > The quaternary system does not present quaternary azeotropes. - Abstract: Experimental isobaric (vapor + liquid + liquid) and (vapor + liquid) equilibrium data for the ternary system {l_brace}water (1) + cyclohexane (2) + heptane (3){r_brace} and the quaternary system {l_brace}water (1) + ethanol (2) + cyclohexane (3) + heptane (4){r_brace} were measured at 101.3 kPa. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer was used to determine the VLLE. The results obtained show that the system does not present quaternary azeotropes. The point-by-point method by Wisniak for testing the thermodynamic consistency of isobaric measurements was used to test the equilibrium data.

  16. Tracing hydrological millennial-scale cycles in the late Quaternary of the Cariaco Basin and the southern Gulf of Cádiz using coccoliths and dinoflagellate cysts

    OpenAIRE

    Mertens, Kenneth

    2009-01-01

    Climate fluctuations in tropical to subtropical regions are coupled to hydrological changes. The reconstruction of these hydrological changes during rapid late Quaternary climate oscillations is crucial for climate change study. The present study demonstrates that coccoliths and dinoflagellate cysts are very useful as paleoclimatological indicators for the elucidation or a better understanding of the late Quaternary regional and global palaeoclimate. This study also reveals new insights in co...

  17. Clay Mineralogical Study of the Pliocene-Pleistocene Carcar Formation and the Quaternary Alluvium in Consolacion-Liloan, Cebu Province, Philippines

    OpenAIRE

    ALETA, Dennis Gerald A.; TOMITA, Katsutoshi; ALETA, Josephine T.; LUPO, Elena S.; KAWANO, Motoharu

    2003-01-01

    The Pliocene-Pleistocene Carcar Formation and the Quaternary Alluvium are two major lithologies that rim the entire island province of Cebu. The Carcar Formation (CaF) is predominantly limestone rock mass characterized by rolling to hilly topography while the Quaternary Alluvium (QA1) is generally unconsolidated sedimentary deposit on coastal plain marked by low relief and undulating landscape. Mineralogical examinations of the vertisolic soil/clay horizons that mantle these rock formations w...

  18. Freshwater gastropods of Neogene and Quaternary lake systems of Europe - state of the art and outlook

    Science.gov (United States)

    Neubauer, Thomas A.; Harzhauser, Mathias; Mandic, Oleg; Kroh, Andreas

    2013-04-01

    Globally, about 4000 extant species of freshwater gastropod species have been described. In contrast, only 225 species are listed by MollBase2012 for North- and Central Europe. Many of these are rare species, limited to certain springs and in fact the typical diversity of gastropods in lakes of North and Central Europe is much lower. The high number is boosted by several highly speciose endemic radiations in long-lived ancient lakes, which are hotspots for biodiversity. These long-lived ancient lakes provide key examples for understanding evolutionary processes and therefore are intensively studied. During the Neogene, Europe's geodynamic history gave rise to several such long-lived lakes with conspicuous endemic radiations. However, these lacustrine systems are rare today as well as in the past compared to the enormous numbers of "normal" lakes. Most extant European lakes are mainly results of the Ice Ages and are due to their geologically temporary nature largely confined to the Pleistocene-Holocene. Also deposits of streams, springs, and groundwater, which today are inhabited by species-rich gastropod assemblages, are rarely preserved. Thus, the pre-Quaternary lacustrine record is biased towards long-lived systems. Apart from few general overviews precise studies on the γ-diversities of the post-Oligocene European lake systems and the shifting biodiversity in European freshwater systems through space and time are entirely missing. Even for the modern faunas, literature on large-scale freshwater gastropod diversity in extant lakes is scarce and lacks a statistical approach. Building upon a great amount of existing literature, a new project will provide the first detailed assessment of the composition of European freshwater gastropods during the Neogene and Quaternary at species, genus and family levels, with emphasis on lake faunas. The γ-diversity of several hundred modern and fossil European lakes will be evaluated. Data will be made available permanently for

  19. The Unseen Founders Of Quaternary Science - The Men Of Glasgow, Scotland (Invited)

    Science.gov (United States)

    Rose, J.

    2010-12-01

    Louis Agassiz (1807-1873) and Charles Lyell (1797-1875) are widely regarded as the founders of Quaternary Science, and there is no doubt that they played their part: Agassiz in 1840 presented and promoted his case for the wide-scale fluctuations of glaciers, and Lyell, through his books and contacts, did much to introduce the subject which we now know as climate change. However there are a number of individuals who contributed to the founding of Quaternary Science who are not so readily recognised and a remarkable fact is that a significant proportion were men without academic training or background who come from, or worked in Glasgow or the adjacent region of central Scotland. First amongst the Glaswegians was James Smith (1782-1867) who, in 1836 presented a paper to the Geological Society of London (where it was duly ignored) in which he suggested, on the basis of fossils dredged from the bed of the Clyde and experience of sailing around Iceland, that the climate of Scotland had been as cold as that of Iceland in the recent past. In 1841, Charles Maclaren (1782-1866) a journalist from Edinburgh, but using information based on raised shorelines near Glasgow proposed what we now know as the glacio-eustatic theory in which the variations in glacier extent control the level of the sea. Perhaps the most important of all was James Croll (1821- 1890) who worked on the theory of ice ages, based on orbital forcing, while janitor at the Andersonian Institute and Museum in Glasgow between 1859-1867. This work was the true precursor to the Milankovitch theory which provides the explanation for the major predictable elements of climate change. Robert Jack (1845-1921) from Irvine, southwest of Glasgow, while doing fieldwork for the British Geological Survey near Loch Lomond close to Glasgow, described in 1874 evidence for non-glacial conditions between tills and clearly recognised that climate could change from glacial to temperate and then glacial climate, before returning to

  20. The eruption history of the quaternary Eifel volcanic fields: Implications from the ELSA - Tephra - Stack

    Science.gov (United States)

    Förster, Michael; Sirocko, Frank

    2015-04-01

    Numerous tephra layers occur in maar sediments in the quaternary Eifel volcanic fields. The sediments were systematically drilled and cored since 1998 by the Eifel Laminated Sediment Archive project (ELSA) (Sirocko et al. 2013). These maar sediments are laminated and the tephra is easily recognizeable by a coarser grain size. Additionaly, tephra layers appear dark grey to black in color. The ashes were sieved to a fraction of 250 - 100 µm and sorted into grains of: reddish and greyish sandstone, quartz, amphibole, pyroxene, scoria and pumice, sanidine, leucite and biotite. A minimum of 100 grains for each tephra layer were used for a sediment petrographic tephra characterisation (SPTC). The grain counts resemble the vol. -% of each grain species. Three types of tephra could be identified by their distinctive grain pattern: (1) phreatomagmatic tephra, rich in basement rocks like greyish/reddish sandstone and quartz. (2) Strombolian tephra, rich in scoria and mafic minerals like pyroxene. (3) evolved tephra, rich in sanidine and pumice. 16 drill-cores, covering the last 500 000 years have been examined. Younger cores were dated by 14C ages and older cores by optical stimulated luminescence. Independently from this datings, the drill-cores were cross-correlated by pollen and the occurences of specific marker-tephra layers, comprising characteristic grain-types. These marker-tephra layers are especially thick and of evolved composition with a significant abundance of sanidine and pumice. The most prominent tephra layers of this type are the Laacher See tephra, dated to 12 900 b2k by Zolitschka (1998), the 40Ar/39Ar dated tephra layers of Dümpelmaar, Glees and Hüttenberg, dated to 116 000 b2k, 151 000 b2k and 215 000 b2k by van den Bogaard & Schmincke (1990), van den Bogaard et al. (1989). These datings set the time-frame for the eruption-phases of the quaternary Eifel Volcanic Fields. Our study refines these findings and shows that phases of activity are very

  1. Late Quaternary marginal marine deposits and palaeoenvironments from northeastern Buenos Aires Province, Argentina: A review

    Science.gov (United States)

    Aguirre, M. L.; Whatley, R. C.

    The late Quaternary marginal marine deposits along eastern Argentina (Southwestern Atlantic) are reviewed according to our present knowledge. In the northeastern coastal area of Buenos Aires Province they have been assigned to a series of transgressions and regressions ranging from the late Pliocene to the late Quaternary. The most widely accepted model is Frenguelli's (1957) classical chronostratigraphical scheme of: 'Belgranense', late Pleistocene marine sediments at 3-6 m above m.s.l. and ca. 26,000->35,000 14C years BP, the 'Querandinense', Pleistocene-Holocene estuarine sediments below or at present m.s.l., and the most extensive 'Platense', mid-Holocene marine deposits at 4.5-2 m above m.s.l. dated at ca. 8000-1340 14C years BP. The restricted 'Belgranense' deposits, recorded in Samborombon Bay, in Magdalena at ca. 32,000 BP, near Mar Chiquita at ca. 24,900 and 30,500 BP and southwards in Bahía Blanca at ca. 26,000-35,500 BP, may belong to an interstadial (González et al., 1986). The molluscan composition suggests a marine invasion of the area but not a typical interglacial cycle characterized by euhaline and warm water elements. However, the oxygen isotope record argues against an interstadial during the interval 34-27 ka and the chronological control for these deposits is very poor, suggesting that they most probably have been elevated neotectonically. The Pleistocene-Holocene 'Querandinense' deposits, extensively distributed along the Bonaerensian coastal plain and continental shelf (ca. 11,000 14C years BP), with very low faunal diversity, abundance of freshwater ostracods and absence of the warm water molluscs characteristic of the Holocene ridges, indicate low salinity and cool water conditions. Further dating and isotope analysis of these deposits are required for a better understanding of the chronology of climatic events by the end of the Pleistocene in this area and to establish whether or not they could correspond to the Younger Dryas event of

  2. Glacial meltwater impounding: Evidence from the late Quaternary glaciogenic sediments in the Sangla valley, district Kinnaur, Himachal Pradesh, India

    Indian Academy of Sciences (India)

    R K Ganjoo; M N Koul

    2005-08-01

    Sangla valley is situated at an altitude of ∼3500m above mean sea level and lies in the Kinnaur district of Himachal Pradesh. It is fed by river Baspa, a tributary of river Sutlej, that entrenches through the Quaternary glaciogenic deposits before emerging out of the valley and joining the river Sutlej at Karcham. The unstratified to stratified glaciogenic deposits consist of large boulders to fine silt and are classified into four major depositional facies on the basis of sedimentary texture and depositional environment. The facies — basal conglomerates, debris flow, water/sheet flow and laminites — represents the change in the environment of deposition from glaciofluvial to lacustrine and also the extent of the glacier to the valley floor during late Quaternary.

  3. Synthesis and crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gerzon E., E-mail: gerzon@ula.ve [Laboratorio de Cristalografía, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Quintero, Eugenio; Tovar, Rafael; Grima-Gallardo, Pedro; Quintero, Miguel [Centro de Estudio de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of)

    2014-11-15

    Highlights: • New quaternary compound. • Synthesis from solid state reaction. • Crystal structure. • Rietveld refinement. - Abstract: The crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}, belonging to the system I–II{sub 2}–III–VI{sub 4}, was characterized by Rietveld refinement using X-ray powder diffraction data. The powder pattern was composed by 84.5% of the principal phase AgFe{sub 2}GaTe{sub 4} and 15.5% of the secondary phase FeTe. This material crystallizes with stannite structure in the tetragonal space group I-42m (N° 121), Z = 2, unit cell parameters a = 6.3409(2) Å, c = 12.0233(4) Å, V = 483.42(3) Å{sup 3}, and is isostructural with CuFe{sub 2}InSe{sub 4}.

  4. Porous polymers bearing functional quaternary ammonium salts as efficient solid catalysts for the fixation of CO2 into cyclic carbonates.

    Science.gov (United States)

    Cai, Sheng; Zhu, Dongliang; Zou, Yan; Zhao, Jing

    2016-12-01

    A series of porous polymers bearing functional quaternary ammonium salts were solvothermally synthesized through the free radical copolymerization of divinylbenzene (DVB) and functionalized quaternary ammonium salts. The obtained polymers feature highly cross-linked matrices, large surface areas, and abundant halogen anions. These polymers were evaluated as heterogeneous catalysts for the synthesis of cyclic carbonates from epoxides and CO2 in the absence of co-catalysts and solvents. The results revealed that the synergistic effect between the functional hydroxyl groups and the halide anion Br(-) afforded excellent catalytic activity to cyclic carbonates. In addition, the catalyst can be easily recovered and reused for at least five cycles without significant loss in activity. PMID:27365001

  5. Climate and humans set the place and time of Proboscidean extinction in late Quaternary of South America

    DEFF Research Database (Denmark)

    Lima-Ribeiro, Matheus Souza; Nogues, David Bravo; Terribile, Levi Carina;

    2013-01-01

    The late Quaternary extinctions have been widely debated for a long time, but the varying magnitude of human vs. climate change impacts across time and space is still an unresolved question. Here we assess the geographic range shifts in response to climate change based on Ecological Niche Models...... Proboscideans. Our results herein support a strong effect of climatic changes on geographical range dynamics of Proboscideans throughout late Quaternary, although this does not fully support climate change as the single cause of their extinctions. We show that both Proboscideans were narrowly distributed...... of these impacts vary across space and time. Indeed, climate changes set the place where the Proboscideans were extinct in South America, whereas the humans set the time of these extinctions. (C) 2013 Elsevier B.V. All rights reserved....

  6. Assessment by X-ray diffraction the process of bentonite organophilization using a different quaternary ammonium salts

    International Nuclear Information System (INIS)

    The process was conducted in an organophilization Bentonite originated from the Company of Industrial Minerals of Mozambique Ltd. (Mimoc). The transformation of bentonite organophilic clay were performed in laboratory procedures that aim to mechanochemical exchange of Na+ and Ca2+ from the interlayer space of clay minerals by cations of quaternary ammonium salts. In this study we used two types of salts, which are: the cetyl trimethyl ammonium chloride and alkyl dimethyl benzyl ammonium chloride at different concentrations (30, 50, 80, 100 meq/100 g clay). The natural bentonite and organophilic clay samples were characterized by X-ray diffraction (XRD) to obtain the mineralogical constituents and analysis phases of the increase in interlayer distance confirming the incorporation of quaternary ammonium salts in the structure of clays. (author)

  7. Superhydrophobic cotton fabric coating based on a complex layer of silica nanoparticles and perfluorooctylated quaternary ammonium silane coupling agent

    Science.gov (United States)

    Yu, Minghua; Gu, Guotuan; Meng, Wei-Dong; Qing, Feng-Ling

    2007-01-01

    A superhydrophobic complex coating for cotton fabrics based on silica nanoparticles and perfluorooctylated quaternary ammonium silane coupling agent (PFSC) was reported in this article. The complex thin film was prepared through a sol-gel process using cotton fabrics as a substrate. Silica nanoparticles in the coating made the textile surface much rougher, and perfluorooctylated quaternary ammonium silane coupling agent on the top layer of the surface lowered the surface free energy. Textiles coated with this coating showed excellent water repellent property, and water contact angle (CA) increased from 133° on cotton fabrics treated with pure PFSC without silica sol pretreatment up to 145°. The oil repellency was also improved and the contact angle of CH 2I 2 droplet on the fabric surface reached to 131°. In contrast, the contact angle of CH 2I 2 on the fabric surface treated with pure PFSC was only 125°.

  8. Southern East Siberia PlioceneeQuaternary faults:Database, analysis and inference

    Institute of Scientific and Technical Information of China (English)

    Oksana V. Lunina; Riccardo Caputo; Anton A. Gladkov; Andrey S. Gladkov

    2014-01-01

    This paper presents the first release of an Informational System (IS) devoted to the systematic collection of all available data relating to PlioceneeQuaternary faults in southern East Siberia, their critical analysis and their seismotectonic parameterization. The final goal of this project is to form a new base for improving the assessment of seismic hazard and other natural processes associated with crustal defor-mation. The presented IS has been exploited to create a relational database of active and conditionally active faults in southern East Siberia (between 100º-114º E and 50º-57ºN) whose central sector is characterized by the highly seismic Baikal rift zone. The information within the database for each fault segment is organized as distinct but intercorrelated sections (tables, texts and pictures, etc.) and can be easily visualized as HTML pages in offline browsing. The preliminary version of the database distributed free on disk already highlights the general fault pattern showing that the Holocene and historical activity is quite uniform and dominated by NEeSW and nearly EeW trending faults;the former with a prevailing dip-slip normal kinematics, while the latter structures are left-lateral strike-slip and oblique-slip (with different proportion of left-lateral and normal fault slip components). These faults are mainly concen-trated along the borders of the rift basins and are the main sources of moderate-to-strong (M≧5.5) earthquakes on the southern sectors of East Siberia in recent times. As a whole, based on analyzing the diverse fault kinematics and their variable spatial distribution with respect to the overall pattern of the tectonic structures formed and/or activated during the late PlioceneeQuaternary, we conclude they were generated under a regional stress field mainly characterized by a relatively uniform NWeSE tension, but strongly influenced by the irregular hard boundary of the old Siberian craton. The obtained inferences are in an

  9. Late Quaternary landscape evolution in the Great Karoo, South Africa: Processes and drivers.

    Science.gov (United States)

    Oldknow, Chris; Hooke, Janet; Lang, Andreas

    2016-04-01

    The Great Karoo spans the north-central part of South Africa at a major climatic boundary. The characteristics, sequences, spatial patterns and drivers of river response to Late Quaternary climate changes in this region remain unclear due to the fragmentary alluvial/colluvial stratigraphic record and the lack of dated palaeoclimatic archives. Dendritic gully networks incised into deep deposits (up to 6 m) of colluvium and alluvium in the upper Sundays River catchment expose a legacy of "cut and fill" features. In 1st order tributaries, these are predominantly discontinuous palaeochannels and flood-outs with localised palaeosols, whereas in 2nd & 3rd order tributaries there are: 1) incised palaeo-geomorphic surfaces, 2) semi-continuous inset terrace sequences, 3) buried palaeo-gully topography. Using a combination of field mapping, logging of sediment outcrops, soil micromorphological and grain size analysis, mineral magnetic measurements and radiometric dating (OSL & 14C), we derive a stratigraphic evolution model which demonstrates a) the number of phases of incision, aggradation and pedogenesis, b) the spatial and temporal extent of each phase and c) the drivers of alluviation and associated feedbacks. Our reconstruction of regional valley alluviation indicates four distinct terrace units of contrasting depositional age. The base of the succession reflects slow aggradation under periglacial conditions associated with the Last Glacial Maximum. Subsequent channel entrenchment, causing terrace abandonment (T1) occurred in the deglacial period when vegetation and rainfall were in anti-phase. Re-instatement of connectivity with deep upland colluvial stores resulted in the injection of a pulse of sediment to valley floors, triggering compartmentalised backfilling (aggradation of T2) which propagated upstream as far as the second order drainage lines. This backfilling restructured the local hydrology, which, in concert with enhanced summer-rainfall, contributed to a

  10. A quaternary lead based perovskite structured materials with diffuse phase transition behavior

    International Nuclear Information System (INIS)

    Graphical abstract: (a) Curie–Weiss plot for the inverse of the relative dielectric permittivity and (b) log (1/ε − 1/εm) as function of log (T − Tm) for ceramics at 1 kHz. Highlights: ► Retaining phase pure structure with quaternary complex stoichiometric compositions. ► P–E loops with good saturation polarization (Ps ∼ 30.7 μC/cm2). ► Diffused relaxor phase transition behavior with γ estimated is ∼1.65. -- Abstract: A lead based quaternary compound composed of 0.25(PbZr0.52Ti0.48O3) + 0.25(PbFe0.5Ta0.5O3) + 0.25 (PbF0.67W0.33O3) + 0.25(PbFe0.5Nb0.5O3) – (PZT–PFT–PFW–PFN) was synthesized by conventional solid-state reaction techniques. It showed moderate high dielectric constant, low dielectric loss, and two diffuse phase transitions, one below the room temperature ∼261 K and other above ∼410 K. X-ray diffraction (XRD) patterns revealed a tetragonal crystal structure at room temperature where as scanning electron micrograph (SEM) indicates inhomogeneous surface with an average grain size of 500 nm–3 μm. Well saturated ferroelectric hysteresis loops with good saturation polarization (spontaneous polarization, Ps ∼ 30.68 μC/cm2) were observed. Temperature-dependent ac conductivity displayed low conductivity with kink in spectra near the phase transition. In continuing search for developing new ferroelectric materials, in the present study we report stoichiometric compositions of complex perovskite ceramic materials: (PZT–PFT–PFW–PFN) with diffuse phase transition behavior. The crystal structure, dielectric properties, and ferroelectric properties were characterized by XRD, SEM, dielectric spectroscopy, and polarization. 1/ε versus (T) plots revealed diffuse relaxor phase transition (DPT) behavior. The compositional variation on the phase transition temperature, dielectric constant, and ferroelectric to paraelectric phase transitions are discussed.

  11. Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments

    Directory of Open Access Journals (Sweden)

    M.-C. Ciobanu

    2012-09-01

    Full Text Available An interdisciplinary study was conducted to evaluate the relationship between geological and paleoenvironmental parameters and the bacterial and archaeal community structure of two contrasting subseafloor sites in the Western Mediterranean Sea (Ligurian Sea and Gulf of Lion. Both depositional environments in this area are well-documented from paleoclimatic and paleooceanographic point of views. Available data sets allowed us to calibrate the investigated cores with reference and dated cores previously collected in the same area, and notably correlated to Quaternary climate variations. DNA-based fingerprints showed that the archaeal diversity was composed by one group, Miscellaneous Crenarchaeotic Group (MCG, within the Gulf of Lion sediments and of nine different lineages (dominated by MCG, South African Gold Mine Euryarchaeotal Group (SAGMEG and Halobacteria within the Ligurian Sea sediments. Bacterial molecular diversity at both sites revealed mostly the presence of the classes Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria within Proteobacteria phylum, and also members of Bacteroidetes phylum. The second most abundant lineages were Actinobacteria and Firmicutes at the Gulf of Lion site and Chloroflexi at the Ligurian Sea site. Various substrates and cultivation conditions allowed us to isolate 75 strains belonging to four lineages: Alpha-, Gammaproteobacteria, Firmicutes and Actinobacteria. In molecular surveys, the Betaproteobacteria group was consistently detected in the Ligurian Sea sediments, characterized by a heterolithic facies with numerous turbidites from a deep-sea levee. Analysis of relative betaproteobacterial abundances and turbidite frequency suggested that the microbial diversity was a result of main climatic changes occurring during the last 20 ka. Statistical direct multivariate canonical correspondence

  12. New Geophysical and Geotechnical Data on Quaternary Layers in the Metropolitan Area of Bucharest

    Science.gov (United States)

    Florin Balan, Stefan; Ritter, Joachim; Bala, Andrei; Rohn, Joachim

    2010-05-01

    Quaternary layers were added to the already organised database. This database is a valuable collection of elastic and dynamic parameters of the Quaternary sedimentary layers obtained by direct measurements. It will be used for further studies on the seismic microzonation of Bucharest City using the equivalent linear approach, like that employed by Bala et al. (2007). The spectral acceleration diagrams computed for the new 10 sites in Bucharest will contribute directly to an improvement of the seismic microzonation of the city and to a better understanding of the links between the geological characteristics of each layer, the geotechnical parameters and the actual future ground motion scenarios. Sponsored by NATO's Science for Peace Programme.

  13. Neogene-Quaternary tectonic stratigraphy of the eastern Southern Alps, NE Italy

    Science.gov (United States)

    Caputo, R.; Poli, M. E.; Zanferrari, A.

    2010-07-01

    In order to reconstruct the Neogene-Quaternary Tectonic Stratigraphy of the eastern Southern Alps, the late Tortonian-lower Pleistocene foredeep clastic sequences, cropping out in the Veneto and Friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers (pitted pebbles). The eastern Southern Alps is the result of a typical polyphase tectonic activity initiated in Late Oligocene, characterised by the occurrence of several non-coaxial stress regimes. Based on careful analyses of the pebbles' surfaces (shape and orientation of the indented features) and following a systematic and statistical approach, the mean orientation of the maximum compressive stress axis (σ 1) has been obtained for more than 30 sites of measurements along the ca. 120 km-long investigated piedmont area. The affected lithostratigraphic units and the orientation (pre- versus post-tilting) of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean σ 1 direction and timing: late Tortonian ( σ1 = 313°/00°), late Messinian-Early Pliocene (338°/04°), Late Pliocene (314°/03°), and Early-Middle Pleistocene (160°/03°). The Tectonic Stratigraphy of the eastern Southern Alps during the last ca. 10 Ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the σ 1 axis between an NNW-SSE and NW-SE directions (Twist Tectonics). Taking also into account literature data about older deformational events (Chattian-Burdigalian and Serravallian-Tortonian), we analyse the Neogene-Quaternary tectonic evolution in the frame of the central Mediterranean realm and compare it with the convergence direction between the Adria-Africa and Europe lithospheric plates. We show that compressional directions within the eastern Southern Alps are basically governed by the remote plate convergence, though since late

  14. Evidence for alternative quaternary structure in a bacterial Type III secretion system chaperone

    Energy Technology Data Exchange (ETDEWEB)

    Barta, Michael L.; Zhang, Lingling; Picking, Wendy L.; Geisbrecht, Brian V. (UMKC); (OKLU)

    2010-10-05

    Type III secretion systems are a common virulence mechanism in many Gram-negative bacterial pathogens. These systems use a nanomachine resembling a molecular needle and syringe to provide an energized conduit for the translocation of effector proteins from the bacterial cytoplasm to the host cell cytoplasm for the benefit of the pathogen. Prior to translocation specialized chaperones maintain proper effector protein conformation. The class II chaperone, Invasion plasmid gene (Ipg) C, stabilizes two pore forming translocator proteins. IpgC exists as a functional dimer to facilitate the mutually exclusive binding of both translocators. In this study, we present the 3.3 {angstrom} crystal structure of an amino-terminally truncated form (residues 10-155, denoted IpgC10-155) of the class II chaperone IpgC from Shigella flexneri. Our structure demonstrates an alternative quaternary arrangement to that previously described for a carboxy-terminally truncated variant of IpgC (IpgC{sup 1-151}). Specifically, we observe a rotationally-symmetric 'head-to-head' dimerization interface that is far more similar to that previously described for SycD from Yersinia enterocolitica than to IpgC1-151. The IpgC structure presented here displays major differences in the amino terminal region, where extended coil-like structures are seen, as opposed to the short, ordered alpha helices and asymmetric dimerization interface seen within IpgC{sup 1-151}. Despite these differences, however, both modes of dimerization support chaperone activity, as judged by a copurification assay with a recombinant form of the translocator protein, IpaB. Conclusions: From primary to quaternary structure, these results presented here suggest that a symmetric dimerization interface is conserved across bacterial class II chaperones. In light of previous data which have described the structure and function of asymmetric dimerization, our results raise the possibility that class II chaperones may

  15. Evidence for alternative quaternary structure in a bacterial Type III secretion system chaperone

    Directory of Open Access Journals (Sweden)

    Picking Wendy L

    2010-07-01

    Full Text Available Abstract Background Type III secretion systems are a common virulence mechanism in many Gram-negative bacterial pathogens. These systems use a nanomachine resembling a molecular needle and syringe to provide an energized conduit for the translocation of effector proteins from the bacterial cytoplasm to the host cell cytoplasm for the benefit of the pathogen. Prior to translocation specialized chaperones maintain proper effector protein conformation. The class II chaperone, Invasion plasmid gene (Ipg C, stabilizes two pore forming translocator proteins. IpgC exists as a functional dimer to facilitate the mutually exclusive binding of both translocators. Results In this study, we present the 3.3 Å crystal structure of an amino-terminally truncated form (residues 10-155, denoted IpgC10-155 of the class II chaperone IpgC from Shigella flexneri. Our structure demonstrates an alternative quaternary arrangement to that previously described for a carboxy-terminally truncated variant of IpgC (IpgC1-151. Specifically, we observe a rotationally-symmetric "head-to- head" dimerization interface that is far more similar to that previously described for SycD from Yersinia enterocolitica than to IpgC1-151. The IpgC structure presented here displays major differences in the amino terminal region, where extended coil-like structures are seen, as opposed to the short, ordered alpha helices and asymmetric dimerization interface seen within IpgC1-151. Despite these differences, however, both modes of dimerization support chaperone activity, as judged by a copurification assay with a recombinant form of the translocator protein, IpaB. Conclusions From primary to quaternary structure, these results presented here suggest that a symmetric dimerization interface is conserved across bacterial class II chaperones. In light of previous data which have described the structure and function of asymmetric dimerization, our results raise the possibility that class II

  16. Three-dimensional sedimentary architecture of Quaternary deposits; a case study of environmental sedimentology (Bam, Iran)

    Science.gov (United States)

    Rezaei, K.; Guest, B.; Friedrich, A.; Fayazi, F.; Nakhaei, M.; Bakhtiari, H.; Nouri, L.

    2009-04-01

    Detailed 3-D analysis of the sedimentary structure and stratigraphy of these deposits allows for an accurate understand of sedimentary model of basin. This paper presents a case study in Bam (SE Iran) reconstructing the 3-D distribution of fluvial sediments based on a high resolution, process-orientated sedimentary facies classification and lithostratigraphy. We investigated the mean grain size with vertical and horizontal change of it, clay mineralogy, sediment texture, sedimentary structures, petrology and petrography and determination of paleo-environments and finally, we prepared two cross sections in S-N and W-E directions and a 3D block diagram for the situation of changes in subsurface sediments and compare them with the destruction rate map of earthquake in Bam city. Quaternary alluvial sediments are characterized by lithofacies deposited by braided river channels, debris flows and hyperconcentrated flows. The channel flow deposits constitute relatively well sorted, well imbricated and clast-supported gravels with coarse to medium sand matrix. Mostly poorly sorted, weakly imbricated to disorganized matrix supported pebble to boulder gravels with silty sand represent debris flow deposits. Hyperconcentrated flow deposits consist of clast-supported, poorly developed sorted polymodal gravel facies with poorly developed imbricated fabric, and generally occupy the lower parts of the terrace and fan sequences. The alternation from hyperconcentrated flow to channel flow deposits is predominant in the sequence, and is possibly the response to different climate modes. The high discharge and supply of sediments as well as the dispersal and deposition of these materials in the trunk stream is attributed to climatic perturbations during the Quaternary. These models allow quantifying the thickness and volume distribution of sandy gravel and clay deposits. We correlate these sedimentary units on the basis of lithofacies similarities, stratigraphic position. These

  17. High Resolution Quaternary Seismic Stratigraphy of the New York Bight Continental Shelf

    Science.gov (United States)

    Schwab, William C.; Denny, J.F.; Foster, D.S.; Lotto, L.L.; Allison, M.A.; Uchupi, E.; Swift, B.A.; Danforth, W.W.; Thieler, E.R.; Butman, Bradford

    2003-01-01

    A principal focus for the U.S. Geological Survey (USGS) Coastal and Marine Geology Program (marine.usgs.gov) is regional reconnaissance mapping of inner-continental shelf areas, with initial emphasis on heavily used areas of the sea floor near major population centers. The objectives are to develop a detailed regional synthesis of the sea-floor geology in order to provide information for a wide range of management decisions and to form a basis for further investigations of marine geological processes. In 1995, the USGS, in cooperation with the U.S. Army Corps of Engineers (USACOE), New York District, began to generate reconnaissance maps of the continental shelf seaward of the New York - New Jersey metropolitan area. This mapping encompassed the New York Bight inner-continental shelf, one of the most heavily trafficked and exploited coastal regions in the United States. Contiguous areas of the Hudson Shelf Valley, the largest physiographic feature on this segment of the continental shelf, also were mapped as part of a USGS study of contaminated sediments (Buchholtz ten Brink and others, 1994; 1996). The goal of the reconnaissance mapping was to provide a regional synthesis of the sea-floor geology in the New York Bight area, including: (a) a description of sea-floor morphology; (b) a map of sea-floor sedimentary lithotypes; (c) the geometry and structure of the Cretaceous strata and Quaternary deposits; and (d) the geologic history of the region. Pursuing the course of this mapping effort, we obtained sidescan-sonar images of 100 % of the sea floor in the study area. Initial interpretations of these sidescan data were presented by Schwab and others, (1997a, 1997b, 2000a). High-resolution seismic-reflection profiles collected along each sidescan-sonar line used multiple acoustic sources (e.g., watergun, CHIRP, Geopulse). Multibeam swath-bathymetry data also were obtained for a portion of the study area (Butman and others, 1998;). In this report, we present a series

  18. Pliocene-Quaternary contourites along the northern Gulf of Cadiz margin: sedimentary stacking pattern and regional distribution

    Science.gov (United States)

    Llave, Estefanía; Matias, Hugo; Hernández-Molina, F. Javier; Ercilla, Gemma; Stow, Dorrik A. V.; Medialdea, Teresa

    2011-12-01

    This study reports novel findings on the Pliocene-Quaternary history of the northern Gulf of Cadiz margin and the spatiotemporal evolution of the associated contourite depositional system. Four major seismic units (P1, P2, QI and QII) were identified in the Pliocene-Quaternary sedimentary record based on multichannel seismic profiles. These are bounded by five major discontinuities which, from older to younger, are the M (Messinian), LPR (lower Pliocene revolution), BQD (base Quaternary discontinuity), MPR (mid-Pleistocene revolution) and the actual seafloor. Unit P1 represents pre-contourite hemipelagic/pelagic deposition along the northern Gulf of Cadiz margin. Unit P2 reflects a significant change in margin sedimentation when contourite deposition started after the Early Pliocene. Mounded elongated and separated drifts were generated during unit QI deposition, accompanied by a general upslope progradation of drifts and the migration of main depocentres towards the north and northwest during both the Pliocene and Quaternary. This progradation became particularly marked during QII deposition after the mid-Pleistocene (MPR). Based on the spatial distribution of the main contourite depocentres and their thickness, three structural zones have been identified: (1) an eastern zone, where NE-SW diapiric ridges have controlled the development of two internal sedimentary basins; (2) a central zone, which shows important direct control by the Guadalquivir Bank in the south and an E-W Miocene palaeorelief structure in the north, both of which have significantly conditioned the basin-infill geometry; and (3) a western zone, affected in the north by the Miocene palaeorelief which favours deposition in the southern part of the basin. Pliocene tectonic activity has been an important factor in controlling slope morphology and, hence, influencing Mediterranean Outflow Water pathways. Since the mid-Pleistocene (MPR), the sedimentary stacking pattern of contourite drifts has been

  19. Quaternary stratigraphy and geologic history of the Charlie Lake (NTS 94A) map-area, British Columbia

    OpenAIRE

    Hartman, Gregory

    2005-01-01

    Two Cordilleran and three Laurentide glacial advances are recorded by Quaternary sediments in the Charlie Lake map-area (NTS 94A). The advances are inferred from the presence of exotic clasts derived from the Canadian Shield, fluvial deposits, glaciolacustrine deposits, and tills within nested paleo-valleys excavated during three interglaciations. The Late Wisconsinan Laurentide glaciation was the most extensive Laurentide glaciation, and the only one recognized in western Alberta south of th...

  20. Stable isotope composition of bulk and secondary carbonates from the Quaternary loess-paleosol sequence in Sutto, Hungary

    DEFF Research Database (Denmark)

    Koeniger, Paul; Barta, Gabriella; Thiel, Christine;

    2014-01-01

    Stable carbon and oxygen isotope composition of pedogenic carbonates were studied from the Quaternary loess-paleosol sequence of Sutto in Hungary to investigate genetic processes in a paleoenvironmental context and to distinguish subtypes. Bulk carbonate samples taken at 2 cm vertical resolution,...... matter or vegetation. Secondary carbonates are more reliable than bulk samples because of their direct connection to the host strata. (C) 2012 Elsevier Ltd and INQUA. All rights reserved....

  1. Elastic properties of quaternary oxyarsenide LaOFeAs as basic phase for new 26-52K superconductors

    OpenAIRE

    Shein, I. R.; IVANOVSKII A.L.

    2008-01-01

    The full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential has been applied to predict the elastic properties of quaternary oxyarsenide LaOFeAs - the basic phase for the newly discovered 26-52K superconductors. The optimized lattice parameters, independent elastic constants (Cij), bulk modulus B, compressibility betta, and shear modulus G are evaluated and discussed. For the first time the numeri...

  2. Ring-Contraction Strategy for the Practical, Scalable, Catalytic Asymmetric Synthesis of Versatile γ-Quaternary Acylcyclopentenes

    KAUST Repository

    Hong, Allen Y.

    2011-02-24

    Contraction action! A simple protocol for the catalytic asymmetric synthesis of highly functionalized γ-quaternary acylcyclopentenes (see schematic) in up to 91 % overall yield and 92 % ee has been developed. The reaction sequence employs a palladium-catalyzed enantioselective alkylation reaction and exploits the unusual stability of β-hydroxy cycloheptanones to achieve a general and robust method for performing two-carbon ring contractions.

  3. Discovery of the first Quaternary maar in the Bohemian Massif, Central Europe, based on combined geophysical and geological surveys

    Czech Academy of Sciences Publication Activity Database

    Mrlina, Jan; Kämpf, H.; Kroner, C.; Mingram, J.; Stebich, M.; Brauer, A.; Geissler, W.H.; Kallmeyer, J.; Matthes, H.; Seidl, Michal

    2009-01-01

    Roč. 182, č. 1-2 (2009), s. 97-112. ISSN 0377-0273 R&D Projects: GA AV ČR IAA300460602 Institutional research plan: CEZ:AV0Z30120515 Keywords : Eger Rift * Quaternary maar volcanism * geophysical survey * Saalian lake sediments * volcanic hazard potential Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.921, year: 2009

  4. Effect of Quaternary Ammonium Carboxymethylchitosan on Release Rate In-vitro of Aspirin Sustained-release Matrix Tablets

    OpenAIRE

    Meng, Lingbin; Teng, Zhongqiu; Zheng, Nannan; Meng, Weiwei; Dai, Rongji; Deng, Yulin

    2013-01-01

    The aim of this study was to develop a derivative of chitosan as pharmaceutical excipient used in sustained-release matrix tablets of poorly soluble drugs. A water-soluble quaternary ammonium carboxymethylchitosan was synthesized by a two-step reaction with carboxymethylchitosan (CMCTS), decylalkyl dimethyl ammonium and epichlorohydrin. The elemental analysis showed that the target product with 10.27% of the maximum grafting degree was obtained. To assess the preliminary safety of this biopol...

  5. Quaternary (liquid + liquid) equilibrium data for the extraction of toluene from alkanes using the ionic liquid [EMim][MSO4

    International Nuclear Information System (INIS)

    Highlights: • EMim[MSO4] was proposed as solvent for the extraction of toluene from alkanes. • The quaternary system {heptane + cyclohexane + toluene + [EMim][MSO4]} was evaluated. • The extraction of toluene would be facilitated in the presence of one alkane. • Experimental LLE data were successfully correlated with the NRTL model. - Abstract: (Liquid + liquid) equilibrium (LLE) studies for the extraction of aromatics from alkanes present in the petroleum fractions are important to develop theoretical/semiempirical (liquid + liquid) equilibrium models, which are used in the design of extraction processes. In this work, the ionic liquid 1-ethyl-3-methylimidazolium methylsulfate, [EMim][MSO4], was evaluated as potential solvent for the separation of toluene from heptane and cyclohexane. The LLE data for the quaternary system {heptane (1) + cyclohexane (2) + toluene (3) + [EMim][MSO4] (4)} were experimentally determined at T = 298.15 K and atmospheric pressure. Moreover, the LLE data for the ternary systems {heptane or cyclohexane (1) + toluene (2) + [EMim][MSO4] (3)} were also determined. Solute distribution ratios and selectivities were calculated and analysed in order to evaluate the capability of the ionic liquid to accomplish the separation target. A comparison between the solute distribution ratios and selectivities for the quaternary and the ternary systems was also made. Finally, the experimental tie-line data were correlated with the NRTL model

  6. An evaluation of deep thin coal seams and water-beating/resisting layers in the quaternary system using seismic inversion

    Institute of Scientific and Technical Information of China (English)

    XU Yong-zhong; HUANG Wei-chuan; CHEN Tong-jun; CUI Ruo-fei; CHEN Shi-zhong

    2009-01-01

    Non-liner wave equation inversion, wavelet analysis and artificial neural networks were used to obtain stratum parame-ters and the distribution of thin coal seams. The lithology of the water-bearing/resisting layer in the Quaternary system was also predicted. The implementation process included calculating the well log parameters, stratum contrasting the seismic data and the well logs, and extracting, studying and predicting seismic attributes. Seismic inversion parameters, including the layer velocity and wave impedance, were calculated and effectively used for prediction and analysis. Prior knowledge and seismic interpretation were used to remedy a dearth of seismic data during the inversion procedure. This enhanced the stability of the inversion method. Non-linear seismic inversion and artificial neural networks were used to interpret coal seismic lithology and to study the wa-ter-bearing/resisting layer in the Quaternary system. Interpretation of the 1-2 m thin coal seams, and also of the wa-ter-bearing/resisting layer in the Quaternary system, is provided. The upper mining limit can be lifted from 60 m to 45 m. The pre-dictions show that this method can provide reliable data useful for thin coal seam exploitation and for lifting the upper mining limit, which is one of the principles of green mining.

  7. Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation.

    Science.gov (United States)

    Price, Randi; Wan, Ping

    2010-01-01

    A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples. PMID:21140668

  8. Nano-sized quaternary CuGa2In3S8 as an efficient photocatalyst for solar hydrogen production

    KAUST Repository

    Kandiel, Tarek

    2014-09-03

    The synthesis of quaternary metal sulfide (QMS) nanocrystals is challenging because of the difficulty to control their stoichiometry and phase structure. Herein, quaternary CuGa2In3S8 photocatalysts with a primary particle size of ≈4nm are synthesized using a facile hot-injection method by fine-tuning the sulfur source injection temperature and aging time. Characterization of the samples reveals that quaternary CuGa2In3S8 nanocrystals exhibit n-type semiconductor characteristics with a transition band gap of ≈1.8eV. Their flatband potential is located at -0.56V versus the standard hydrogen electrode at pH6.0 and is shifted cathodically by 0.75V in solutions with pH values greater than 12.0. Under optimized conditions, the 1.0wt% Ru-loaded CuGa2In3S8 photocatalyst exhibits a photocatalytic H2 evolution response up to 700nm and an apparent quantum efficiency of (6.9±0.5)% at 560nm. These results indicate clearly that QMS nanocrystals have great potential as nano-photocatalysts for solar H2 production. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. LATE QUATERNARY SEISMIC SEQUENCES AND SEDIMENTATION ALONG THE COAST OFF TAISHAN,GUANGDONG,AS REVEALED BY HIGH RESOLUTION SEISMIC DATA

    Institute of Scientific and Technical Information of China (English)

    吴时国; 黄孝健

    2002-01-01

    Seismic stratigraphic analysis of 150 km of high-resolution seismic profiles (G E OPULSE and 3.5 kHz) obtained along the muddy coast off Taishan, Guangdong pr ovided valuable information on the offshore Quaternary stratigraphy, tectonics, sedimentary evol ution, and environmental and engineering geology of this area.The following late Quaternary stratigraphic sequences were mapped. (1) Pleistoce ne alluvial silty sand and shallow marine clay; (2) coarse fluvial channel sand; (3 ) nearshore and bay clayey sediments. The incision of fluvial channels occurred in two stages: duri ng the Late Pleistocene and at the beginning of the Holocene. The Pleistocene fluvial channe ls have been filled by coarse sand overlain by more than 10 m of late Pleistocene clay and 20-30 m o f Holocene clay.The coastal area is dissected by two major fault systems: the first group strike s ENE-WSW and controls the evolution of the adjacent Quaternary basin, while the second one tr ends NNE-SSW. These fault systems must be taken into account in any coastal engineering consid erations. In addition, both granitic and metamorphic basements were recognized.

  10. In situ cosmogenic 10Be dating of the Quaternary glaciations in the southern Shaluli Mountain on the Southeastern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG; Jian; Raisbeck; Grand; XU; Xiaobin; Yiou; Francios; BAI; Shibiao

    2006-01-01

    It is generally considered that four-times ice age happened during the Quaternary epoch on the Tibetan Plateau.However,the research on the chronology of the four-times ice age is far from enough.The Shaluli Mountain on the Southeastern Tibetan Plateau is an ideal place for plaeo-glacier study,because there are abundant Quaternary glacial remains there.This paper discusses the ages of the Quaternary glaciations,based on the exposure dating of roche moutonnée,moraines and glacial erosion surfaces using in situ cosmogenic isotopes 10Be.It is found that the exposure age of the roche moutonnée at Tuershan is 15 ka,corresponding to Stage 2 of the deep-sea oxygen isotope,suggesting that the roche moutonnée at Tuershan is formed in the last glacial maximum.The exposure age of glacial erosion surface at Laolinkou is 130-160 ka,corresponding to Stage 6 of the deep-sea oxygen isotope.The oldest end moraine at Kuzhaori may form at 421-766 kaBP,corresponding to Stages 12-18 of the deep-sea oxygen isotope.In accordance with the climate characteristic of stages 12,14,16 and 18 reflected by the deep-sea oxygen isotope,polar ice cores and loess sequence,the oldest end moraine at Kuzhaori may form at stage 12 or stage 16,the latter is more possible.

  11. Climate change not to blame for late Quaternary megafauna extinctions in Australia.

    Science.gov (United States)

    Saltré, Frédérik; Rodríguez-Rey, Marta; Brook, Barry W; Johnson, Christopher N; Turney, Chris S M; Alroy, John; Cooper, Alan; Beeton, Nicholas; Bird, Michael I; Fordham, Damien A; Gillespie, Richard; Herrando-Pérez, Salvador; Jacobs, Zenobia; Miller, Gifford H; Nogués-Bravo, David; Prideaux, Gavin J; Roberts, Richard G; Bradshaw, Corey J A

    2016-01-01

    Late Quaternary megafauna extinctions impoverished mammalian diversity worldwide. The causes of these extinctions in Australia are most controversial but essential to resolve, because this continent-wide event presaged similar losses that occurred thousands of years later on other continents. Here we apply a rigorous metadata analysis and new ensemble-hindcasting approach to 659 Australian megafauna fossil ages. When coupled with analysis of several high-resolution climate records, we show that megafaunal extinctions were broadly synchronous among genera and independent of climate aridity and variability in Australia over the last 120,000 years. Our results reject climate change as the primary driver of megafauna extinctions in the world's most controversial context, and instead estimate that the megafauna disappeared Australia-wide ∼13,500 years after human arrival, with shorter periods of coexistence in some regions. This is the first comprehensive approach to incorporate uncertainty in fossil ages, extinction timing and climatology, to quantify mechanisms of prehistorical extinctions. PMID:26821754

  12. Late Quaternary fluvial terraces near the Daocheng Ice Cap, eastern Tibetan Plateau

    Science.gov (United States)

    Xu, Liubing; Zhou, Shangzhe

    2014-05-01

    The timing of terrace formation relative to the glacial-interglacial cycle and what factors control that timing, such as changes in climate and/or uplift, are controversial. Here we present a study of the terraces along the Yazheku River using electron spin resonance (ESR) dating and analysis of the sedimentary characteristics in order to establish the timing of terrace formation and to assess the forcing mechanisms that have been proposed. The Yazheku River flows in glacial trough leading from the Haizi Shan, on the eastern Tibetan Plateau. The range was uplifted during the Quaternary and repeatedly glaciated by ice caps. The four highest major terraces (T5, T4, T3, and T2) are the result of both climatic and tectonic influences. Strath terraces T5-T2 were created during Haizi Shan glacial expansions during MIS 16, 12, 6 and 3-4, respectively. The major aggradation phases of the four terraces occurred during the deglaciations at the ends of MIS 16, 12, 6, and 2. Down-cutting, which led to the generation of the four terraces, immediately followed the deposition of the T5-T2 gravel units. These incisions occurred during the transitions between MIS 16-15, MIS 12-11, MIS 6-5, and MIS 2-1.

  13. Optical absorption analysis of quaternary molybdate- and tungstate-ordered double perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Tablero, C., E-mail: ctablero@etsit.upm.es

    2015-08-05

    Highlights: • These compounds present a high optical absorption. • The absorption coefficients using different DFT + U alternatives have been compared. • The absorption coefficients have been split into different contributions. • The maximum efficiency is near the maximum efficiency for multiple-gap solar cells. - Abstract: Quaternary-ordered double perovskite A{sub 2}MM′O{sub 6} (M = Mo,W) semiconductors are a group of materials with a variety of photocatalytic and optoelectronic applications. An analysis focused on the optoelectronic properties is carried out using first-principles density-functional theory with several U orbital-dependent one-electron potentials applied to different orbital subspaces. The structural non-equivalence of the atoms resulting from the symmetry has been taken in account. In order to analyze optical absorption in these materials deeply, the absorption coefficients have been split into inter- and intra-non-equivalent species contributions. The results indicate that the effect of the A and M′ atoms on the optical properties are minimal whereas the largest contribution comes from the non-equivalent O atoms to M transitions.

  14. Taxonomy of quaternary deep-sea ostracods from the Western North Atlantic ocean

    Science.gov (United States)

    Yasuhara, Moriaki; Okahashi, H.; Cronin, T. M.

    2009-01-01

    Late Quaternary sediments from Ocean Drilling Program (ODP) Hole 1055B, Carolina Slope, western North Atlantic (32??47.041??? N, 76??17.179??? W; 1798m water depth) were examined for deep-sea ostracod taxonomy. A total of 13933 specimens were picked from 207 samples and c. 120 species were identified. Among them, 87 species were included and illustrated in this paper. Twenty-eight new species are described. The new species are: Ambocythere sturgio, Argilloecia abba, Argilloecia caju, Argilloecia keigwini, Argilloecia robinwhatleyi, Aversovalva carolinensis, Bythoceratina willemvandenboldi, Bythocythere eugeneschornikovi, Chejudocythere tenuis, Cytheropteron aielloi, Cytheropteron demenocali, Cytheropteron didieae, Cytheropteron richarddinglei, Cytheropteron fugu, Cytheropteron guerneti, Cytheropteron richardbensoni, Eucytherura hazeli, Eucytherura mayressi, Eucytherura namericana, Eucytherura spinicorona, Posacythere hunti, Paracytherois bondi, Pedicythere atroposopetasi, Pedicythere kennettopetasi, Pedicythere klothopetasi, Pedicythere lachesisopetasi, Ruggieriella mcmanusi and Xestoleberis oppoae. Taxonomic revisions of several common species were made to reduce taxonomic uncertainty in the literature. This study provides a robust taxonomic baseline for application to palaeoceanographical reconstruction and biodiversity analyses in the deep and intermediate-depth environments of the North Atlantic Ocean. ?? The Palaeontological Association, 2009.

  15. Applying DEM-SRTM for reconstructing a late Quaternary paleodrainage in Amazonia

    Science.gov (United States)

    Hayakawa, Ericson H.; Rossetti, Dilce F.; Valeriano, Márcio M.

    2010-08-01

    Remote sensing is a particularly invaluable tool that has helped the detection of paleomorphologies produced by river dislocation in a variety of landscapes, which has contributed in reconstructing the geological evolution of many fluvial systems. This technique might provide useful information to discuss the evolution of large fluvial systems, in special those located in areas of difficult access where the acquisition of field data is difficult. Application of remote sensing for paleodrainage characterization in densely vegetated tropical areas is scarce in the literature. This work records processing of the Digital Elevation Model (DEM) derived from the Shuttle Radar Topography Mission (SRTM), which succeeded in revealing an ancient drainage complex of the Madeira River, one of the main Amazonas tributaries, where other remote sensing products failed the detection. Analysis of this paleodrainage and of its modern counterpart within the geological framework available for this region leads to propose that activity along pre-existent faults during the latest Quaternary would have promoted the southeastward dislocation of a nearly 200 km long segment of the Madeira River. During this process, an impressive paleodrainage network was left behind, which was only able to be detected using the DEM-SRTM. Application of this technique might be of great help to the detection of paleodrainage morphologies in densely vegetated areas similar to the Amazonas lowland. The dynamics of channel migration in this and many other large scale tropical river systems might benefit from the investigation based on data derived from DEM-SRTM.

  16. Chemical, biochemical, and microbiological aspects of chitosan quaternary salt as active coating on sliced apples

    Directory of Open Access Journals (Sweden)

    Douglas de Britto

    2012-09-01

    Full Text Available The biocompatibility of chitosan and chitosan quaternary salt coatings was evaluated for use as edible coatings for sliced apple. Measurement of water loss, color change, and fungal growth appearance were monitored as a function of time. A significant brownish effect was observed on chitosan coated slices, varying greatly from L* = 76.5 and Hue angle = 95.9° (t = 0 to L* = 45.3 and Hue angle = 69.8° (t = 3 days, whilst for TMC coated samples the variation was considerable lower (L* = 74.1; Hue angle = 95.0° to (L* = 67.0; Hue angle = 83.8° within the same period. The hydrosoluble derivative N,N,N-trimethylchitosan demonstrated good antifungal activity against P. expansum although highly dependent on the polymer properties such as degree of quaternization. The most efficient formulation was that prepared from derivative having a degree of quaternization of 45%, high solubility, and high viscosity. This formulation restrained fungus spreading up to 30%, while for the control it reached almost 80% of the total assessed surfaces during 7 days of storage.

  17. Enhanced insights into late Quaternary African hydroclimate dynamics using a water-isotope enabled climate model

    Science.gov (United States)

    Singarayer, Joy; Holloway, Max

    2016-04-01

    The climate of intertropical Africa is strongly governed by the dynamics of the tropical rainbelt, which is often associated with the Intertropical Convergence Zone (ITCZ). On millennial time-scales the primary drivers of variation in the rainbelt include orbital configuration changes to insolation seasonality and high-latitude forcing (e.g. Heinrich events). The spatial pattern of precipitation variability in tropical and subtropical Africa over the late Quaternary is complex and has long been debated. Stable water isotopes from inland lakes and off-shore ocean core records have provided longitudinal records, variously interpreted as changes to precipitation intensity or changes to moisture source location due to atmospheric circulation changes (or a combination of several factors). In this preliminary study we have used a global climate model, HadCM3, in which water isotopes are interactively coupled to produce snapshots at 1000-year intervals covering the last deglaciation (21kyr to pre-industrial). In conjunction with a comparison to available palaeodata, this enables us to better elucidate the connections between precipitation and other climate factors with changes to the water isotope signature, as well as how this varies regionally and through time.

  18. Synthesis and characterization of antibacterial polyurethane coatings from quaternary ammonium salts functionalized soybean oil based polyols.

    Science.gov (United States)

    Bakhshi, Hadi; Yeganeh, Hamid; Mehdipour-Ataei, Shahram; Shokrgozar, Mohammad Ali; Yari, Abbas; Saeedi-Eslami, Seyyed Nasirodin

    2013-01-01

    In this study, a simple and versatile synthetic approach was developed to prepare bactericidal polyurethane coatings. For this purpose, introduction of both quaternary ammonium salts (QASs), with well-known antibacterial activity, and reactive hydroxyl groups on to the backbone of soybean oil was considered. Epoxidized soybean oil was reacted with diethylamine and the intermediate tertiary amine containing polyol was reacted with two different alkylating agents, methyl iodide and benzyl chloride, to produce MQAP and BQAP, respectively. These functional polyols were reacted with different diisocyanate monomers to prepare polyurethane coatings. Depending on the structure of monomers used for the preparation of polyurethane coatings, initial modulus, tensile strength and elongation at break of samples were in the ranges of 122-339 MPa, 4.6-12.4 MPa and 8.4-46%, respectively. Polyurethane coatings based on isophorone diisocyanate showed proper mechanical properties and adhesion strength (0.41 MPa) for coating application. Study of fibroblast cells interaction with prepared polyurethanes showed promising cells viability in the range of 78-108%. Meanwhile, MQAP based samples with higher concentration of QASs showed better adhesion strength, surface hydrophilicity and antibacterial activity (about 95% bacterial reduction). Therefore, these materials can find applications as bactericidal coating for biomedical devices and implants. PMID:25428057

  19. Multifunctional properties related to magnetostructural transitions in ternary and quaternary Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dubenko, Igor, E-mail: igor_doubenko@yahoo.com [Department of Physics, Southern Illinois University, Carbondale, IL 62901 (United States); Quetz, Abdiel; Pandey, Sudip; Aryal, Anil; Eubank, Michael [Department of Physics, Southern Illinois University, Carbondale, IL 62901 (United States); Rodionov, Igor; Prudnikov, Valerii; Granovsky, Alexander [Faculty of Physics, Moscow State University, Vorob' evy Gory, 11999I Moscow (Russian Federation); Lahderanta, Erkki [Lappeenranta University of Technology, 53851 (Finland); Samanta, Tapas; Saleheen, Ahmad; Stadler, Shane [Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Ali, Naushad [Department of Physics, Southern Illinois University, Carbondale, IL 62901 (United States)

    2015-06-01

    In this report, the results of a study on the effects of compositional variations induced by the small changes in concentrations of the parent components and/or by the substitution of Ni, Mn, or In by an extra element Z, on the phase transitions, and phenomena related to the magnetostructural transitions in off-stoichiometric Ni–Mn–In based Heusler alloys are summarized. The crystal structures, phase transitions temperatures, and magnetic and magnetocaloric properties were analyzed for representative samples of the following systems (all near 15 at% indium concentration): Ni–Mn–In, Ni–Mn–In–Si, Ni–Mn–In–B, Ni–Mn–In–Cu, Ni–Mn–In–Cu–B, Ni–Mn–In–Fe, Ni–Mn–In–Ag, and Ni–Mn–In–Al. - Highlights: • The experimental results on phase transitions temperatures, adiabatic temperature changes, magnetoresistance and heat flow for the ternary and quaternary Heusler alloys based on Ni{sub 50}Mn{sub 35}In{sub 15} demonstrate high sensitivity of magnetic properties to the small changes in concentrations of the parent components and/or by the substitution of Ni, Mn, or In by an additional element Z. • The phenomena related to the magnetostructural transitions strongly depend on the weighted average radius of constituent ions.

  20. Evolution of Protein Quaternary Structure in Response to Selective Pressure for Increased Thermostability.

    Science.gov (United States)

    Fraser, Nicholas J; Liu, Jian-Wei; Mabbitt, Peter D; Correy, Galen J; Coppin, Chris W; Lethier, Mathilde; Perugini, Matthew A; Murphy, James M; Oakeshott, John G; Weik, Martin; Jackson, Colin J

    2016-06-01

    Oligomerization has been suggested to be an important mechanism for increasing or maintaining the thermostability of proteins. Although it is evident that protein-protein contacts can result in substantial stabilization in many extant proteins, evidence for evolutionary selection for oligomerization is largely indirect and little is understood of the early steps in the evolution of oligomers. A laboratory-directed evolution experiment that selected for increased thermostability in the αE7 carboxylesterase from the Australian sheep blowfly, Lucilia cuprina, resulted in a thermostable variant, LcαE7-4a, that displayed increased levels of dimeric and tetrameric quaternary structure. A trade-off between activity and thermostability was made during the evolution of thermostability, with the higher-order oligomeric species displaying the greatest thermostability and lowest catalytic activity. Analysis of monomeric and dimeric LcαE7-4a crystal structures revealed that only one of the oligomerization-inducing mutations was located at a potential protein-protein interface. This work demonstrates that by imposing a selective pressure demanding greater thermostability, mutations can lead to increased oligomerization and stabilization, providing support for the hypothesis that oligomerization is a viable evolutionary strategy for protein stabilization. PMID:27016206

  1. Sedimentation rates and age modeling of Late Quaternary marine sediments with unsupported 230Th

    International Nuclear Information System (INIS)

    230Th is a radionuclide of the 238U decay series, characterized by natural abundance in sediments and a half-life of 75,380 years, suitable for direct evaluation of sedimentation rates and sediment ages in a time scale of 700,000 years before the present. 230Th cycle creates a contrast between supported and unsupported 230Th in the sedimentary matrix due to the different geochemical behaviors of 230Th and its parent, 234U. This study aimed at establishing and validating a mathematical model that evaluates sedimentation rates and age modeling based on 230Th data retrieved from a sediment core sampled in the southeastern Brazilian continental margin. The validation of the age modeling of this method was made through a statistical comparison between its results and those of benthic foraminifera δ 18O record technique, widely used for sediment dating and determination of sedimentation rates. It was observed that the model of unsupported 230Th was successful in determining Late Quaternary sedimentation rates and ages in a confidence level of 95 %. It was possible to determine several breaking points in unsupported 230Th vertical profile, and it was shown that those divides correspond to some major intervals between glacial and interglacial periods when compared with the benthic foraminifera record. (author)

  2. Structural optimization and segregation behavior of quaternary alloy nanoparticles based on simulated annealing algorithm

    Science.gov (United States)

    Xin-Ze, Lu; Gui-Fang, Shao; Liang-You, Xu; Tun-Dong, Liu; Yu-Hua, Wen

    2016-05-01

    Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles. Project supported by the National Natural Science Foundation of China (Grant Nos. 51271156, 11474234, and 61403318) and the Natural Science Foundation of Fujian Province of China (Grant Nos. 2013J01255 and 2013J06002).

  3. Preparation and characterization of montmorillonite modified by phosphorus-nitrogen containing quaternary ammonium salts

    International Nuclear Information System (INIS)

    A novel class of phosphorous-nitrogen containing quaternary ammonium salts (PNQAS) were synthesized and used as modifiers for sodium montmorillonite (Na-MMT). Montmorillonites modified by PNQAS (PNQAS-MMT) were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), dispersibility measurement and thermogravimetric analysis (TGA). The results show that the PNQAS have been intercalated into the montmorillonite layers successfully and the basal spacing of PNQAS-MMT is 1.70-2.65 nm. The XRD results show that the basal spacing of PNQAS-MMT reaches a maximum when PNQAS/CEC molar ratio is above 1.2. The increase of chain length of PNQAS is beneficial to expand the interlayer space of the MMT. The TEM and dispersibility measurement results show that PNQAS-MMT have stronger hydrophobicity and better dispersion than Na-MMT. The TGA results reveal that the thermal stability for PNQAS-MMT is affected by the structure and composition of intercalated PNQAS cations. The Tinital of PNQAS-MMT is between 286 °C and 385 °C, which can be applied to the modification of the polymer as a halogen-free flame retardant.

  4. The atmospheric corrosion of quaternary bronzes: An evaluation of the dissolution rate of the alloying elements

    Science.gov (United States)

    Bernardi, E.; Chiavari, C.; Martini, C.; Morselli, L.

    2008-07-01

    A comparative evaluation of the corrosion behaviour of a G85 bronze in acid rain solutions was performed. As weathering technique, a wet dry device was used to simulate a cyclic exposure to stagnant rain. The weathering solutions were a collected natural rain and an artificial solution reproducing the natural rain. The solutions were periodically monitored as concerns pH and metallic ion concentrations. On the aged specimens, surface studies were performed through OM, SEM and Raman analyses. At the end of weathering tests (40 days), weight loss measurements were carried out. The aim of this work was to examine the reproducibility in laboratory of the corrosive conditions determined by a natural acid rain. The final goal of this research is to investigate the dissolution of a quaternary alloy exposed to acid rains. The results showed slightly different corrosion behaviours as a consequence of the exposure to natural or synthetic rain. Concerning the mechanism of corrosion of G85 bronze, the innovative approach adopted in this study allowed one to point out the contribution of each alloying element to the general corrosion. Actually, while Cu and Pb progressively form insoluble corrosion compounds, Zn continuously dissolves, without forming detectable insoluble products. The absence of dissolved tin is remarkable.

  5. Quaternary Ice-Age dynamics in the Colombian Andes: developing an understanding of our legacy.

    Science.gov (United States)

    Hooghiemstra, Henry; Van der Hammen, Thomas

    2004-02-29

    Pollen records from lacustrine sediments of deep basins in the Colombian Andes provide records of vegetation history, the development of the floristic composition of biomes, and climate variation with increasing temporal resolution. Local differences in the altitudinal distribution of present-day vegetation belts in four Colombian Cordilleras are presented. Operating mechanisms during Quaternary Ice-Age cycles that stimulated speciation are discussed by considering endemism in the asteraceous genera Espeletia, Espeletiopsis and Coespeletia. The floristically diverse lower montane forest belt (1000-2300 m) was compressed by ca. 55% during the last glacial maximum (LGM) (20 ka), and occupied the slopes between 800 m and 1400 m during that period. Under low LGM atmospheric pCO2 values, C4-dominated vegetation, now occurring below 2200 m, expanded up to ca. 3500 m. Present-day C3-dominated paramo vegetation is therefore not an analogue for past C4-dominated vegetation (with abundant Sporobolus lasiophyllus). Quercus immigrated into Colombia 478 ka and formed an extensive zonal forest from 330 ka when former Podocarpus-dominated forest was replaced by zonal forest with Quercus and Weinmannia. During the last glacial cycle the ecological tolerance of Quercus may have increased. In the ecotone forests Quercus was rapidly and massively replaced by Polylepis between 45 and 30 ka illustrating complex forest dynamics in the tropical Andes. PMID:15101574

  6. The Pliocene and Quaternary formations of El Abalario, in the Huelva province littoral (Spain)

    International Nuclear Information System (INIS)

    The study of new and ancient boreholes in El Abalario area (Lower Guadalquivir basin) permitted to identify four main plio-quaternary formations above the Miocene marls, namely: Huelva Sands, Bonares Sands, Almonte Sands and Gravels, and El Abalario Sands. Respectively, they are interpreted as shallow marine, deltaic, alluvial and eolian sediments, together forming a marine to continental sequence that reaches a thickness of more than 250 metres. All sediments are arranged as a gentle dipping and thickening structure to the southeast. Only a few boreholes of the western border of El Abalario reach the top of the Miocene marls. In the rest of the Abalario area the Miocene marls are confined to an unknown level bellow the deepest boreholes. Upward, the marls grade to the Huelva sands, without any appreciable break in the sediments. To the north, the upper part of the Huelva formation grades to the Bonares sands, which is mainly developed outside the study area. Both formations are covered by the coarse clastic deposits of the Almonte formation. At the top, El Abalario sands recover all previous deposits and configure the current relief. This study improves the early existing geology profile and the connection with the surrounding areas (Author).

  7. Quaternary allostratigraphy of surficial deposit map units at Yucca Mountain, Nevada: A progress report

    International Nuclear Information System (INIS)

    Surficial geologic mapping at Yucca Mountain, Nevada, is relevant to site characterization studies of paleoclimate, tectonics, erosion, flood hazards, and water infiltration. Alluvial, colluvial, and eolian allostratigraphic map units are defined on the basis of age-related surface characteristics and soil development, as well as lithology and sedimentology indicative of provenance and depositional mode. In gravelly alluvial units, which include interbedded debris flows, the authors observe a useful qualitative correlation between surface and soil properties. Map units of estimated middle Pleistocene age typically have a well-developed, varnished desert pavement, and minimal erosional and preserved depositional microrelief, associated with a soil with a reddened Bt horizon and stage 3 carbonate and silica morphology. Older units have greater erosional relief, an eroded argillic horizon and stage 4 carbonate morphology, whereas younger units have greater preservation of depositional morphology, but lack well-developed pavements, rock varnish, and Bt and Kqm soil horizons. Trench and gully-wall exposures show that alluvial, colluvial and eolian dominated surface units are underlain by multiple buried soils separating sedimentologically similar deposits; this stratigraphy increases the potential for understanding the long-term Quaternary paleoenvironmental history of Yucca Mountain. Age estimates for allostratigraphic units, presently based on uranium-trend dating and regional correlation using soil development, will be further constrained by ongoing dating studies that include tephra identification, uranium-series disequilibrium, and thermoluminescence methods

  8. Synthesis and Performance Evaluation of Quaternary Ammonium Salt as Potential Shale Inhibitor

    International Nuclear Information System (INIS)

    Melamine and sodium chloroacetate were used as raw materials to synthesize a kind of quaternary ammonium salt (QAS) as potential clay swelling inhibitor and water-based drilling fluid additive, and the reaction conditions were screened based on the linear expansion rate of bentonite. The inhibitive properties of QASs were investigated by various methods, including montmorillonite (MMT) linear expansion test, mud ball immersing test, particle distribution measurement, thermogravimetric analysis and scanning electron microscopy etc. The results indicate that QAS can inhibit expansion and dispersion of clay in water effectively. At the same condition, the bentonite linear expansion rate in QAS-2 solution is much lower than those of others, and the hydration expansion degree of the mud ball in 0.5% QAS-2 solution is appreciably weaker than the control test. The compatibility test indicates QAS-2 could be compatible with the conventional additives in water-based drilling fluids, and the temperature resistance of modified starch was improved effectively. Meanwhile, the inhibitive mechanism was discussed through the particle distribution measurement, thermogravimetric analysis and scanning electron microscopy. (author)

  9. Predicting a quaternary tungsten oxide for sustainable photovoltaic application by density functional theory

    International Nuclear Information System (INIS)

    A quaternary oxide, CuSnW2O8 (CTTO), has been predicted by density functional theory (DFT) to be a suitable material for sustainable photovoltaic applications. CTTO possesses band gaps of 1.25 eV (indirect) and 1.37 eV (direct), which were evaluated using the hybrid functional (HSE06) as a post-DFT method. The hole mobility of CTTO was higher than that of silicon. Further, optical absorption calculations demonstrate that CTTO is a better absorber of sunlight than Cu2ZnSnS4 and CuInxGa1−xSe2 (x = 0.5). In addition, CTTO exhibits rigorous thermodynamic stability comparable to WO3, as investigated by different thermodynamic approaches such as bonding cohesion, fragmentation tendency, and chemical potential analysis. Chemical potential analysis further revealed that CTTO can be synthesized at flexible experimental growth conditions, although the co-existence of at least one secondary phase is likely. Finally, like other Cu-based compounds, the formation of Cu vacancies is highly probable, even at Cu-rich growth condition, which could introduce p-type activity in CTTO

  10. A comprehensive database of quality-rated fossil ages for Sahul's Quaternary vertebrates.

    Science.gov (United States)

    Rodríguez-Rey, Marta; Herrando-Pérez, Salvador; Brook, Barry W; Saltré, Frédérik; Alroy, John; Beeton, Nicholas; Bird, Michael I; Cooper, Alan; Gillespie, Richard; Jacobs, Zenobia; Johnson, Christopher N; Miller, Gifford H; Prideaux, Gavin J; Roberts, Richard G; Turney, Chris S M; Bradshaw, Corey J A

    2016-01-01

    The study of palaeo-chronologies using fossil data provides evidence for past ecological and evolutionary processes, and is therefore useful for predicting patterns and impacts of future environmental change. However, the robustness of inferences made from fossil ages relies heavily on both the quantity and quality of available data. We compiled Quaternary non-human vertebrate fossil ages from Sahul published up to 2013. This, the FosSahul database, includes 9,302 fossil records from 363 deposits, for a total of 478 species within 215 genera, of which 27 are from extinct and extant megafaunal species (2,559 records). We also provide a rating of reliability of individual absolute age based on the dating protocols and association between the dated materials and the fossil remains. Our proposed rating system identified 2,422 records with high-quality ages (i.e., a reduction of 74%). There are many applications of the database, including disentangling the confounding influences of hypothetical extinction drivers, better spatial distribution estimates of species relative to palaeo-climates, and potentially identifying new areas for fossil discovery. PMID:27434208

  11. Distribution of foraminifera in late quaternary sediments off High Island, Hong Kong

    Science.gov (United States)

    Yim, W. W.-S.; He, X.-X.

    The distribution of foraminifera in a borehole off High Island, Hong Kong was investigated to assist Quaternary palaeoenvironmental reconstruction. The results confirmed the existence of an upper and lower marine strata of the Holocene and the last interglacial age respectively, separated by an upper terrestrial stratum of the last glacial age. Diversity and abundance of foraminifera are greater in the upper marine stratum while foraminiferal tests in the lower marine stratum are usually reddish-brown in colour, which is explained by iron-staining during the last glacial low sea-level stand. The latter is underlain by a lower terrestrial stratum and residual soil. The presence of large foraminifera often with broken tests in the upper marine stratum is indicative of a subtropical high energy rocky shore environment during the Holocene period. Unlike previously studied sites in Hong Kong, the present borehole yielded abundant Amphistegina which reflected a sedimentary environment in close proximity to patcy coral reefs. Based on radiocarbon dates obtained elsewhere in Hong Kong, the lower marine stratum is last interstadial in age ranging from ca. 30,000-45,000 yr B.P. However, because of the high elevation of the stratum, palynological and oxygen-isotope evidence, the last interglacial age is considered to be more likely.

  12. Optical absorption analysis of quaternary molybdate- and tungstate-ordered double perovskites

    International Nuclear Information System (INIS)

    Highlights: • These compounds present a high optical absorption. • The absorption coefficients using different DFT + U alternatives have been compared. • The absorption coefficients have been split into different contributions. • The maximum efficiency is near the maximum efficiency for multiple-gap solar cells. - Abstract: Quaternary-ordered double perovskite A2MM′O6 (M = Mo,W) semiconductors are a group of materials with a variety of photocatalytic and optoelectronic applications. An analysis focused on the optoelectronic properties is carried out using first-principles density-functional theory with several U orbital-dependent one-electron potentials applied to different orbital subspaces. The structural non-equivalence of the atoms resulting from the symmetry has been taken in account. In order to analyze optical absorption in these materials deeply, the absorption coefficients have been split into inter- and intra-non-equivalent species contributions. The results indicate that the effect of the A and M′ atoms on the optical properties are minimal whereas the largest contribution comes from the non-equivalent O atoms to M transitions

  13. Late-Quaternary Dynamics of Temperate Forests: Applications of Paleoecology to Issues of Global Environmental Change

    Science.gov (United States)

    Delcourt, Paul A.; Delcourt, Hazel R.

    Paleoecological evidence recently summarized from 162 fossil-pollen sites in eastern North America provides new insights concerning the nature and rate of response of temperate forest ecosystems to late Pleistocene and Holocene environmental changes. Across this subcontinental region (25°N to 60°N; 50°W to 100°W), temperate forests have changed in composition, location and area occupied in adjustment to major episodes of climatic cooling and warming during glacial-interglacial cycles of the Quaternary. Forest taxa have migrated differentially, reflecting their individualistic life-history characteristics, dispersal and competitive abilities, and tolerance thresholds to environmental changes, as well as the geographic distribution of corridors and barriers to plant migration. Gradient analysis and ecological ordination of paleovegetational data illustrate that: (1) both positions and breadth of major vegetational ecotones have shifted latitudinally over the past 20 ka; (2) good modern analogues exist for certain full-glacial warm-temperate and boreal forests; (3) during the transition from Pleistocene to Holocene conditions, mixed conifer-northern hardwoods forests, spreading across newly deglaciated terrain, lacked good analogues within the modern vegetation; and (4) most cool-temperate deciduous forest communities north of 35°N developed in the Holocene. Forest clearance and cultivation by Native Americans along principal riverways resulted in a transformation from natural to cultural landscapes during the mid- and late Holocene intervals. Fragmentation of temperate forests accelerated with the onset of EuroAmerican settlement and technologic developments after the Industrial Revolution.

  14. Fluorosilicone multi-block copolymers tethering quaternary ammonium salt groups for antimicrobial purpose

    Science.gov (United States)

    Zhou, Fang; Qin, Xiaoshuai; Li, Yancai; Ren, Lixia; Zhao, Yunhui; Yuan, Xiaoyan

    2015-08-01

    Symmetrically structured fluorosilicone multi-block copolymers containing poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(hexafluorobutyl methacrylate) (PHFBMA) were sequentially synthesized via reversible addition-fragmentation chain transfer polymerization, using a polydimethylsiloxane (PDMS) chain transfer agent with dithiocarbonate groups at both ends. Then, the CBABC-type block copolymers were quaternized with n-octyliodide to tether quaternary ammonium salt (QAS) groups in the PDMAEMA blocks for the antimicrobial use. The obtained fluorosilicone copolymers showed clear variations in the C-N+ composition and surface morphology on their films depending on the content of the PHFBMA blocks, which were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The results indicated that the symmetrical CBABC structure favored PDMS and QAS tethered blocks migrating to the film surface. With the mass percentage of the PHFBMA increased from 0 to 32.5%, the surface roughness of the copolymer film decreased gradually with a tendency to form a smooth surface. Owing to the surface properties, fluorosilicone multi-block copolymers containing a certain amount of PHFBMA with higher C-N+ content and relatively smooth morphology demonstrated obvious antimicrobial activity against Gram-positive bacteria, Bacillus subtilis and Gram-negative bacteria, Escherichia coli. The functionalized multi-block copolymers based on fluorosilicone and QAS groups would have potential applications in antimicrobial coatings.

  15. Recent advances in the understanding of Quaternary periglacial features of the English Channel coastlands

    Science.gov (United States)

    Murton, Julian B.; Lautridou, Jean-Pierre

    2003-02-01

    Recent advances in the understanding of Quaternary periglaciation of the English Channel coastlands concern laboratory modelling of periglacial processes, dating of periglacial sediments and the distribution of permafrost during marine oxygen isotope stage (MOIS) 2. Modelling studies have successfully simulated (i) ice segregation in chalk in artificial permafrost, (ii) periglacial solifluction of natural slope sediments, and (iii) soft-sediment deformation during thaw of ice-rich soil. The resultant structures and deposits in these experiments have similarities with naturally brecciated chalk, solifluction deposits and involutions, respectively, along the English Channel coastlands, providing insights into their genesis and palaeoenvironmental significance.Dating of periglacial sediments is based on radiocarbon assays of organic material in head deposits, luminescence measurements of loess and coversand, and mammalian biostratigraphy in raised-beach and associated slope deposits. Most age estimates fall within MOIS 2, although some are within MOIS 6 and possibly other cold stages.Maps reconstructing the distribution of permafrost during MOIS 2 vary in detail. The precise distribution of permafrost remains to be established owing to problems of (i) imprecise dating in the context of climatic instability, (ii) uncertain palaeoclimatic significance of particular periglacial structures and (iii) sparse data on the age and distribution of relict periglacial features.The wider significance of periglacial processes to the evolution of the Channel coastlands is speculated to involve rapid valley development by flowing water in areas of moist, frost-susceptible bedrock that has been brecciated by ice segregation.

  16. Characteristics and formation of rain forest soils derived from late Quaternary basaltic rocks in Leyte, Philippines

    Science.gov (United States)

    Navarrete, Ian A.; Tsutsuki, Kiyoshi; Asio, Victor B.; Kondo, Renzo

    2009-09-01

    This study was conducted to evaluate the physical, chemical, and mineralogical characteristics of rain forest soils derived from late Quaternary basaltic rocks in Leyte, Philippines. Four sites along a catena were selected at an elevation of 75-112 m above sea level with an average annual rainfall of 3,000 mm and an average temperature of 28°C. Results indicate that the soils are deep, clayey, and reddish in color, which is indicative of the advanced stage of soil development. They also posses excellent physical condition (friable and highly porous) although they are plastic and sticky when wet as is usual for clayey soils. In terms of chemical characteristics, the soils are acidic with low CEC values and generally low in organic matter and nutrient contents. The clay mineralogy of the soils is dominated by halloysite and kaolinite with minor amounts of goethite and hematite, and they also have generally high dithionite-extractable Fe contents confirming the advanced stage of their development. The soils in the more stable slope positions (PL-1, PL-2, and PL-4) have generally similar characteristics and appeared more developed than the one in the less stable position (PL-3). The most important pedogenic processes that formed the soils appear to be weathering, loss of bases and acidification, desilification, ferrugination, clay formation and translocation, and structure formation. The nature of the parent rock and climatic conditions prevailing in the area as well as slope position appear to have dominant effects on the development of the soils.

  17. Study on quaternary stratigraphy and environmental changes in South Sea, Korea

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jeong-Hae; Lee, Chi-Won; Kim, Sung-Pil [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    According to interpretation of seismic profiles crossing the drilled sites, there are five sequences, namely Unit I, Unit II, Unit III, Unit IV and Unit V from bottom, separable by a reflector with good lateral continuity. If we apply the conception of sequential stratigraphy to the sea level fluctuation caused depositional processes, based on the results of seismic profiles, it will be possible to figure out the late Quaternary depositional processes in the context of sea level changes. According to the sedimentological and seismic stratigraphic analysis, most of SSDP sites showed transgression and regression sequences. Chemical analyses of elements for the sediment samples of SSDP-102 core exhibit the geochemical factors which may influenced the sedimentary environments of the study area. The lower-most sedimentary sequence Unit III can be interpreted as an environment which was influenced dominantly by stronger chemical weathering under a semi-fresh water environment. Based on predominance of carbonate-originated Ca in the homogeneous mud sequence, a high productive surface water along with transgression may have controlled the upper-most sedimentary sequence Unit I. Scatter diagram represents oxygen and carbon isotopic values of benthic foraminifera (Asterorotalia concinna) which is analyzed. All 61 points has value between +1 and -1. If isotopic values of selected benthic foraminifera are equilibrium with surrounding values. These distributions indicate transitional between coastal environment affected by fresh water and open marine environment. (author). 24 refs., 8 tabs., 25 figs.

  18. Miocene to Quaternary deformation, stratigraphy and paleogeography in Northeastern Slovenia and Southwestern Hungary

    Directory of Open Access Journals (Sweden)

    Laszlo Fodor

    2002-06-01

    Full Text Available The Mura-Zala basin was formed due to ENE-WSW trending crustal extension in the late early and middle Miocene (19 – 11 Ma. Marine sedimentation occurred in several more or less confined depressions (half grabens, then in a unified basin. The rifting phasewas probably connected to uplift and brittle-ductile deformation of metamorphic basement at the eastern part of the Pohorje and Kozjak hills. During the late Miocene thermal subsidence, deltaic to fluvial sediments were deposited.After sedimentation, the southernmost Haloze-Budafa sub-basin was inverted. Mapscale folds, reverse and strike-slip faults were originated by NNW-SSE compression during the latest Miocene(?–Pliocene. After this folding, Karpatian sediments of theHaloze acquired magnetization. During the late(?Pliocene to Quaternary(?, the whole Mura-Zala basin, including the folded Haloze, suffered 30° counterclockwise rotation as a relatively rigid block. This rotation affected a wider area from Slovenia to western Hungary and northern Croatia.

  19. Quaternary extrusion rates of the Cascade Range, northwestern United States and southern British Columbia

    Science.gov (United States)

    Sherrod, D.R.; Smith, James G.

    1990-01-01

    Quaternary (2-0 Ma) extrusion rates change significantly along the Cascade Range volcanic arc. The extrusion rate north of Mount Rainier is about 0.21 km3 km-1 m.y.-1; the rate in southern Washington and northern Oregon south to Mount Hood is about 1.6 km3 km-1 m.y.-1; in central Oregon the rate is 3-6 km3 km-1 m.y.-1; and in northern California, the rate is 3.2 km3 km-1 m.y.-1. Eruption style also changes along the arc but at latitudes different from rate changes. At the ends of the arc, volcanism is focused at isolated intermediate to silicic composite volcanoes. The composite volcanoes represent ~30% of the total volume of the arc. Mafic volcanic fields partly ring some composite volcanoes, especially in the south. In contrast, volcanism is diffused in the middle of the arc, where numerous overlapping mafic shields and a few composite volcanoes have built a broad ridge. Contrasting eruption style may signify diffuse versus focused heat sources or may reflect changes in permeability to ascending magma along the arc. -Authors

  20. Nano-sized, quaternary titanium(IV) metal-organic frameworks with multidentate ligands

    Science.gov (United States)

    Baranwal, Balram Prasad; Singh, Alok Kumar

    2010-12-01

    Some mononuclear nano-sized, quaternary titanium(IV) complexes having the general formula [Ti(acac)(OOCR) 2(SB)] (where Hacac = acetylacetone, R = C 15H 31 or C 17H 35, HSB = Schiff bases) have been synthesized using different multidentate ligands. These were characterized by elemental analyses, molecular weight determinations and spectral (FTIR, 1H NMR and powder XRD) studies. Conductance measurement indicated their non-conducting nature which may behave like insulators. Structural parameters like the values of limiting indices h, k, l, cell constants a, b, c, angles α, β, γ and particle size are calculated from powder XRD data for complex 1 which indicated nano-sized triclinic system in them. Bidentate chelating nature of acetylacetone, carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. On the basis of physico-chemical studies, coordination number 8 was assigned for titanium(IV) in the complexes. Transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) studies indicated spherical particles with poor crystallinity.