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Sample records for ftir theoretical structural

  1. Experimental FTIR and FT-Raman and theoretical studies on the molecular structures of monomer and dimer of 3-thiopheneacrylic acid

    Science.gov (United States)

    Issaoui, N.; Ghalla, H.; Brandán, Silvia Antonia; Bardak, F.; Flakus, H. T.; Atac, A.; Oujia, B.

    2017-05-01

    This work presents an experimental and theoretical investigation on the properties of 3-thiopheneacrylic acid (3TAA) by using the FT-Raman and FT-IR spectra in the solid state. The structural, electronic, topological and vibrational properties of 3TAA were theoretically studied by using the hybrid B3LYP method with the 6-311++G (d,p) basis set. The complete assignments of the bands observed in both spectra were performed taking into account the presence of both monomer and dimer species of the acid. Two bands observed at 1682 and 1625 cm-1 attributed to the Cdbnd C and Cdbnd O stretching modes, respectively support the presence of the dimeric species in the solid phase. The percentages of intermolecular interactions are analyzed by Fingerprint plots of Hirshfeld surface. The natural bond orbital (NBO), atoms in molecules (AIM), frontier molecular orbitals (FMOs) and molecular electrostatic potential surface (MEPs) calculations were employed to determine the structural properties while the chemical selectivity or reactivity sites were revealed by using the Fukui functions. The GIAO and time-dependent density functional theory (TD-DFT) methods were used to predict the 1H and 13C NMR and electronic spectra of the acid. The diagrams of the density of state of that acid have been also presented. Finally, reasonable correlations between experimental and theoretical vibrational spectra were found. Effect of positioning and orientation of the acrylic group on the inhibitor characteristics on human MAOB enzyme of stable conformers of 3TAA is investigated in comparison with that of 3-2TAA and four selective inhibitors via molecular docking.

  2. A new tridentate Schiff base Cu(II) complex: synthesis, experimental and theoretical studies on its crystal structure, FT-IR and UV-Visible spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran; Setoodeh, Nasim; Rudbari, Hadi Amiri; Bruno, Giuseppe

    2013-06-01

    A new Cu(II) complex [Cu(L)(NCS)] has been synthesized, using 1-(N-salicylideneimino)-2-(N,N-methyl)-aminoethane as tridentate ONN donor Schiff base ligand (HL). The dark green crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FT-IR) and UV-Visible spectra. Electronic structure calculations at the B3LYP and MP2 levels of theory are performed to optimize the molecular geometry and to calculate the UV-Visible and FT-IR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TD-DFT) method is used to calculate the electronic transitions of the complex. A scaling factor of 1.015 is obtained for vibrational frequencies computed at the B3LYP level using basis sets 6-311G(d,p). It is found that solvent has a profound effect on the electronic absorption spectrum. The UV-Visible spectrum of the complex recorded in DMSO and DMF solution can be correctly predicted by a model in which DMSO and DMF molecules are coordinated to the central Cu atom via their oxygen atoms. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Synthesis, experimental and theoretical studies on its crystal structure and FT-IR spectrum of new thiosemicarbazone compound E-2-(4-isopropylbenzylidene)thiosemicarbazone

    Czech Academy of Sciences Publication Activity Database

    Khalaji, A.D.; Mehrani, S.; Eigner, Václav; Dušek, Michal

    2013-01-01

    Roč. 1047, SEP (2013), s. 87-94 ISSN 0022-2860 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378271 Keywords : thiosemicarbazide * single crystal * FT-IR * 1 H NMR * DFT Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 1.599, year: 2013

  4. Theoretical study on molecular structure and vibrational analysis included FT-IR, FT-Raman and UV techniques of 2,4,5-trimethylbenzoic acid (monomer and dimer structures).

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-05

    Theoretical study on the structural and vibrational analysis of monomer and dimer structures of 2,4,5-trimethylbenzoic acid (2,4,5-TMBA, C₁₀H₁₂O₂) were presented. The geometry of the molecule was fully optimized. The Fourier transform infrared (FT-IR) and the Fourier transform Raman (FT-Raman) spectra of the title molecule in solid phase were recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The geometrical parameters and energies were investigated with the help of Density Functional Theory (DFT) employing B3LYP method and 6-311++G(d,p) basis set. The spectroscopic data of the molecule in the ground state were calculated by using DFT/B3LYP method with the 6-311++G(d,p) basis set. The vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the potential energy distribution (PED) of the vibrational modes. The geometric parameters were compared with experimental data of the title molecule. The UV absorption spectrum of the studied compound was computed and recorded in the range of 190-400 nm dissolved in water and ethanol. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) were calculated and presented. In addition these, thermodynamic properties and Mulliken atomic charges were performed. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. NBO, NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of 4-Chloro-3,5-Xylenol: a combined experimental and theoretical study.

    Science.gov (United States)

    Arivazhagan, M; Gayathri, R

    2013-12-01

    In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab initio) study on the structure and the vibrations of 4-Chloro-3,5-Xylenol (CXL) are compared and analyzed. CXL is a chlorinated phenolic antiseptic which is a bactericide against most gram-positive bacteria. The first hyperpolarizability (β0) of this novel molecular system and related non-linear properties of CXL are calculated using HF/6-311++G(d,p) method on the finite-field approach. The energy and oscillator strength calculated using absorption spectra (UV-Vis spectrum), this spectral analysis confirms the charge transfer of the molecule. The theoretical (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge Including Atomic Orbital (GIAO) method, to analyze the molecular environment as well as the delocalization activities of electron clouds. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), chemical hardness (η), first electron excitation energy (τ) and electrophilicity index (ω) as well as local reactivity (S) analyzed using HOMO and LUMO energies; the energy band gap are also determined. NBO analysis shows that charge in electron density(ED) in the σ(*) and π(*) antibonding orbitals and E((2)) energies confirms the occurrence of ICT (Intramolecular Charge Transfer) within the molecule. Inter molecular hydrogen bonds exist between -OH group, give the evidence for the formation of dimer entities in the title molecule. The influences of chlorine atom, hydroxyl group and methyl group on the geometry of benzene and its normal modes of vibrations (monomer and dimer of CXL) have also been discussed. Finally the calculated results were applied to simulate Infrared and Raman spectra of the title molecule which show good agreement with observed spectra. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. NBO, NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of 4-Chloro-3,5-Xylenol: A combined experimental and theoretical study

    Science.gov (United States)

    Arivazhagan, M.; Gayathri, R.

    2013-12-01

    In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab initio) study on the structure and the vibrations of 4-Chloro-3,5-Xylenol (CXL) are compared and analyzed. CXL is a chlorinated phenolic antiseptic which is a bactericide against most gram-positive bacteria. The first hyperpolarizability (β0) of this novel molecular system and related non-linear properties of CXL are calculated using HF/6-311++G(d,p) method on the finite-field approach. The energy and oscillator strength calculated using absorption spectra (UV-Vis spectrum), this spectral analysis confirms the charge transfer of the molecule. The theoretical 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge Including Atomic Orbital (GIAO) method, to analyze the molecular environment as well as the delocalization activities of electron clouds. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), chemical hardness (η), first electron excitation energy (τ) and electrophilicity index (ω) as well as local reactivity (S) analyzed using HOMO and LUMO energies; the energy band gap are also determined. NBO analysis shows that charge in electron density(ED) in the σ* and π* antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intramolecular Charge Transfer) within the molecule. Inter molecular hydrogen bonds exist between -OH group, give the evidence for the formation of dimer entities in the title molecule. The influences of chlorine atom, hydroxyl group and methyl group on the geometry of benzene and its normal modes of vibrations (monomer and dimer of CXL) have also been discussed. Finally the calculated results were applied to simulate Infrared and Raman spectra of the title molecule which show good agreement with observed spectra.

  7. A new Schiff base compound N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone): synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, 1H NMR and 13C NMR spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran

    2011-10-15

    The Schiff base compound, N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone) (NDHA) is synthesized through the condensation of 2-hydroxylacetophenone and 2,2-dimethyl 1,3-amino propane in methanol at ambient temperature. The yellow crystalline precipitate is used for X-ray single-crystal determination and measuring Fourier transform infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP, PBEPBE and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the FTIR, (1)H NMR and (13)C NMR spectra of the compound. Time-dependent density functional theory (TDDFT) method is used to calculate the UV-visible spectrum of NDHA. Vibrational frequencies are determined experimentally and compared with those obtained theoretically. Vibrational assignments and analysis of the fundamental modes of the compound are also performed. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR and (13)C NMR chemical shifts calculated by all DFT methods are consistent with the experimental data. However, the NMR shielding tensors computed at the B3LYP/6-31+G(d,p) level of theory are in better agreement with experimental (1)H NMR and (13)C NMR spectra. The electronic absorption spectrum calculated at the B3LYP/6-31+G(d,p) level by using TD-DFT method is in accordance with the observed UV-visible spectrum of NDHA. In addition, some quantum descriptors of the molecule are calculated and conformational analysis is performed and the results were compared with the crystallographic data. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. A novel tridentate Schiff base dioxo-molybdenum(VI) complex: synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, ¹H NMR and ¹³C NMR spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran; Stoeckli-Evans, Helen

    2012-09-01

    A new dioxo-molybdenum(VI) complex [MoO(2)(L)(H(2)O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H(2)L) and MoO(2)(acac)(2). The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the UV-visible, FTIR, (1)H NMR and (13)C NMR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TDDFT) method is used to calculate the electronic transitions of the complex. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental (1)H NMR spectra. However, the (13)C NMR shielding tensors computed at the B3LYP level, employing a combined basis set of DGDZVP for Mo and 6-31+G(2df,p) for other atoms, are in better agreement with experimental (13)C NMR spectra. The electronic transitions calculated at the B3LYP/DGDZVP level by using TD-DFT method is in accordance with the observed UV-visible spectrum of the compound. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. FT-Raman and FTIR spectra of photoactive aminobenzazole derivatives in the solid state: A combined experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Rodrigo Martins [Universidade Federal do Pampa, Campus Bagé, Grupo de Pesquisa em Espectroscopia de Materiais Fotônicos, 96400-970 Bagé, RS (Brazil); Rodembusch, Fabiano Severo [Universidade Federal do Rio Grande do Sul, Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Av. Bento Gonçalves 9500, CEP 91501-970 Porto Alegre, RS (Brazil); Habis, Charles [Northern Virginia Community College, Manassas, VA (United States); Moreira, Eduardo Ceretta, E-mail: eduardomoreira@unipampa.edu.br [Universidade Federal do Pampa, Campus Bagé, Grupo de Pesquisa em Espectroscopia de Materiais Fotônicos, 96400-970 Bagé, RS (Brazil)

    2014-12-15

    This study reports the experimental investigation of two photoactive aminobenzazole derivatives in the solid state by FT-Raman and Infrared Spectroscopies (FTIR) and its comparison with theoretical models. The optimized molecular structure, vibrational frequencies, and corresponding vibrational assignments of these compounds have been investigated experimentally and theoretically using Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) and Gaussian03 Software Package. The FT-Raman and FTIR spectra were acquired with high resolution and emission frequencies identified by simulating the vibrational modes. The most intense peak observed in the FT-Raman spectra is the in-plane deformation vibrational of O–H bond that could be related to the vibrational region responsible for the stabilization of the enol conformer in the ground state which undergoes ESIPT to form a keto tautomer in the excited state. Additionally, the position of the amino group played an important role on the vibrational characteristics of the studied compounds. Also, the simulations proved to be a good approach in undertaking the FTIR and FT-Raman experiments. The use of graphic correlations helps us to determine the method and basis that best fit the experimental results. - Highlights: • Structural and vibrational properties of two aminobenzazoles were reported. • Comparison between experimental techniques and theoretical models. • The position of the amino group played an important role on the vibrational characteristics of the studied compounds.

  10. An experimental and theoretical investigation of Acenaphthene-5-boronic acid: conformational study, NBO and NLO analysis, molecular structure and FT-IR, FT-Raman, NMR and UV spectra.

    Science.gov (United States)

    Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M; Cinar, Mehmet

    2013-11-01

    The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400cm(-1) and 4000-10cm(-1), respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability 〈β〉, its components and associated properties such as average polarizability and anisotropy of the polarizability (α and Δα) of AN-5-BA was calculated using the finite-field approach. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Red/blue shifting hydrogen bonds in acetonitrile-dimethyl sulphoxide solutions: FTIR and theoretical studies

    Science.gov (United States)

    Kannan, P. P.; Karthick, N. K.; Mahendraprabu, A.; Shanmugam, R.; Elangovan, A.; Arivazhagan, G.

    2017-07-01

    FTIR spectra of neat acetonitrile (AN), dimethyl sulphoxide (DMSO) and their binary solutions at various mole fractions have been recorded at room temperature. Theoretical calculations have also been carried out on acetonitrile (monomer, dimer), dimethyl sulphoxide (monomer, dimer) and AN - DMSO complex molecules. 1:2 (AN:DMSO) and 2:1 complexation through the red shifting (AN) C - H ⋯ O = S(DMSO) and blue shifting (DMSO) C - H ⋯ N ≡ C(AN) hydrogen bonds has been identified. The experimental and theoretical studies favour the presence of both the monomer and dimer in liquid AN, but only closed dimers in DMSO. The dipole-dipole interactions existed in AN and DMSO dimers disappear in the complex molecules. Partial π bond between S and O atoms, and three lone pair of electrons on oxygen atom of DMSO have been noticed theoretically.

  12. Molecular interaction forces in acetone + ethanol binary liquid solutions: FTIR and theoretical studies

    Science.gov (United States)

    Jadhav, Deepali L.; Karthick, N. K.; Kannan, P. P.; Shanmugam, R.; Elangovan, A.; Arivazhagan, G.

    2017-02-01

    FTIR spectra of neat acetone, ethanol and their binary solutions at the molar ratios 0.2:0.8 (ethanol: acetone), 0.4:0.6, 0.6:0.4 and 0.8:0.2 have been recorded at room temperature. Theoretical calculations have also been made on acetone (monomer and dimer), ethanol monomer, dimer, trimer, tetramer, pentamer, hexamer and ethanol - acetone complex molecules. 4:1 (ethanol:acetone), 5:1 and 6:2 complexation through the classical Cdbnd O⋯Hsbnd O and (acetone) Csbnd H⋯Osbnd C(ethanol) hydrogen bonds has been identified. Ethanol rich solutions may consist of ethanol multimers such as tetramer, pentamer and hexamer along with 4:1, 5:1 and 6:2 complex molecules depending upon ethanol concentration. Acetone seems to exist as a mixture of monomer and dimer.

  13. Science Academies' Refresher Course on Theoretical Structural ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 22; Issue 8. Science Academies' Refresher Course on Theoretical Structural Geology, Crystallography, Mineralogy, Thermodynamics, Experimental Petrology and Theoretical Geophysics. Information and Announcements Volume 22 Issue 8 August 2017 ...

  14. Science Academies' Refresher Course on Theoretical Structural ...

    Indian Academy of Sciences (India)

    A course on Theoretical Structural Geology, Crystallography, Mineralogy, Thermodynamics, Exper- imental Petrology and Theoretical Geophysics will be conducted in the Jallahalli Campus under the aegis of Indian Academy of Sciences during 20th November to 4th December, 2017. University lec- turers, Research ...

  15. Methodological effects in Fourier transform infrared (FTIR) spectroscopy: Implications for structural analyses of biomacromolecular samples

    Science.gov (United States)

    Kamnev, Alexander A.; Tugarova, Anna V.; Dyatlova, Yulia A.; Tarantilis, Petros A.; Grigoryeva, Olga P.; Fainleib, Alexander M.; De Luca, Stefania

    2018-03-01

    A set of experimental data obtained by Fourier transform infrared (FTIR) spectroscopy (involving the use of samples ground and pressed with KBr, i.e. in a polar halide matrix) and by matrix-free transmission FTIR or diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic methodologies (involving measurements of thin films or pure powdered samples, respectively) were compared for several different biomacromolecular substances. The samples under study included poly-3-hydroxybutyrate (PHB) isolated from cell biomass of the rhizobacterium Azospirillum brasilense; dry PHB-containing A. brasilense biomass; pectin (natural carboxylated heteropolysaccharide of plant origin; obtained from apple peel) as well as its chemically modified derivatives obtained by partial esterification of its galacturonide-chain hydroxyl moieties with palmitic, oleic and linoleic acids. Significant shifts of some FTIR vibrational bands related to polar functional groups of all the biomacromolecules under study, induced by the halide matrix used for preparing the samples for spectroscopic measurements, were shown and discussed. A polar halide matrix used for preparing samples for FTIR measurements was shown to be likely to affect band positions not only per se, by affecting band energies or via ion exchange (e.g., with carboxylate moieties), but also by inducing crystallisation of metastable amorphous biopolymers (e.g., PHB of microbial origin). The results obtained have important implications for correct structural analyses of polar, H-bonded and/or amphiphilic biomacromolecular systems using different methodologies of FTIR spectroscopy.

  16. THEORETICAL STUDY ON ELECTRONIC STRUCTURES AND ...

    African Journals Online (AJOL)

    THEORETICAL STUDY ON ELECTRONIC STRUCTURES AND SPECTROSCOPY OF TRIARYLBORANE SUBSTITUTED BY THIOPHENE. ... Also, the 13C chemical shifts of the carbon atoms on the phenyl rings in these compounds are upfield relative to those of the same carbon atoms in the parent compound.

  17. An FTIR investigation of flanking sequence effects on the structure and flexibility of DNA binding sites.

    Science.gov (United States)

    Kahn, Talia R; Fong, Kimberly K; Jordan, Brian; Lek, Janista C; Levitan, Rachel; Mitchell, Patrick S; Wood, Corrina; Hatcher, Mary E

    2009-02-17

    Fourier transform infrared (FTIR) spectroscopy and a library of FTIR marker bands have been used to examine the structure and relative flexibilities conferred by different flanking sequences on the EcoRI binding site. This approach allowed us to examine unique peaks and subtle changes in the spectra of d(AAAGAATTCTTT)(2), d(TTCGAATTCGAA)(2), and d(CGCGAATTCGCG)(2) and thereby identify local changes in base pairing, base stacking, backbone conformation, glycosidic bond rotation, and sugar puckering in the studied sequences. The changes in flanking sequences induce differences in the sugar puckers, glycosidic bond rotation, and backbone conformations. Varying levels of local flexibility are observed within the sequences in agreement with previous biological activity assays. The results also provide supporting evidence for the presence of a splay in the G(4)-C(9) base pair of the EcoRI binding site and a potential pocket of flexibility at the G(4) cleavage site that have been proposed in the literature. In sum, we have demonstrated that FTIR is a powerful methodology for studying the effect of flanking sequences on DNA structure and flexibility, for it can provide information about the local structure of the nucleic acid and the overall relative flexibilities conferred by different flanking sequences.

  18. Theoretical analysis of polarized structure functions

    International Nuclear Information System (INIS)

    Altarelli, G.; ); Ball, R.D.; Forte, S.; Ridolfi, G.

    1998-01-01

    We review the analysis of polarized structure function data using perturbative QCD and NLO We use the most recent experimental data to obtain updated results for polarized parton distributions, first moments and the strong coupling. We also discuss several theoretical issues involving in this analysis and in the interpretation of its results. Finally, we compare our results with other similar analyses in the recent literature. (author)

  19. Theoretical Analysis of Polarized Structure Functions

    CERN Document Server

    Altarelli, Guido; Forte, Stefano; Ridolfi, G

    1998-01-01

    We review the analysis of polarized structure function data using perturbative QCD at next-to-leading order. We use the most recent experimental data to obtain updated results for polarized parton distributions, first moments and the strong coupling. We also discuss several theoretical issues involved in this analysis and in the interpretation of its results. Finally, we compare our results with other similar analyses in the recent literature.

  20. Theoretical nuclear structure. Progress report for 1997

    International Nuclear Information System (INIS)

    Nazarewicz, W.; Strayer, M.R.

    1997-01-01

    This research effort is directed toward theoretical support and guidance for the fields of radioactive ion beam physics, gamma-ray spectroscopy, and the interface between nuclear structure and nuclear astrophysics. The authors report substantial progress in all these areas. One measure of progress is publications and invited material. The research described here has led to more than 25 papers that are published, accepted, or submitted to refereed journals, and to 25 invited presentations at conferences and workshops

  1. Using FT-IR Spectroscopy to Elucidate the Structures of Ablative Polymers

    Science.gov (United States)

    Fan, Wendy

    2011-01-01

    The composition and structure of an ablative polymer has a multifaceted influence on its thermal, mechanical and ablative properties. Understanding the molecular level information is critical to the optimization of material performance because it helps to establish correlations with the macroscopic properties of the material, the so-called structure-property relationship. Moreover, accurate information of molecular structures is also essential to predict the thermal decomposition pathways as well as to identify decomposition species that are fundamentally important to modeling work. In this presentation, I will describe the use of infrared transmission spectroscopy (FT-IR) as a convenient tool to aid the discovery and development of thermal protection system materials.

  2. Theoretical nuclear structure and astrophysics at FAIR

    International Nuclear Information System (INIS)

    Rodríguez, Tomás R

    2014-01-01

    Next generation of radioactive ion beam facilities like FAIR will open a bright future for nuclear structure and nuclear astrophysics research. In particular, very exotic nuclei (mainly neutron rich) isotopes will be produced and a lot of new exciting experimental data will help to test and improve the current nuclear models. In addition, these data (masses, reaction cross sections, beta decay half-lives, etc.) combined with the development of better theoretical approaches will be used as the nuclear physics input for astrophysical simulations. In this presentation I will review some of the state-of-the-art nuclear structure methods and their applications.

  3. Prion structure investigated in situ, ex vivo, and in vitro by FTIR spectroscopy

    Science.gov (United States)

    Kneipp, Janina; Miller, Lisa M.; Spassov, Sashko; Sokolowski, Fabian; Lasch, Peter; Beekes, Michael; Naumann, Dieter

    2004-07-01

    Syrian hamster nervous tissue was investigated by FTIR microspectroscopy with conventional and synchrotron infrared light sources. Various tissue structures from the cerebellum and medulla oblongata of scrapie-infected and control hamsters were investigated at a spatial resolution of 50 μm. Single neurons in dorsal root ganglia of scrapie-infected hamsters were analyzed by raster scan mapping at 6 μm spatial resolution. These measurements enabled us to (i) scrutinize structural differences between infected and non-infected tissue and (ii) analyze for the first time the distribution of different protein structures in situ within single nerve cells. Single nerve cells exhibited areas of increased β-sheet content, which co-localized consistently with accumulations of the pathological prion protein (PrPSc). Spectral data were also obtained from purified, partly proteinase K digested PrPSc isolated from scrapie-infected nervous tissue of hamsters to elucidate similarities/dissimilarities between prion structure in situ and ex vivo. A further comparison is drawn to the recombinant Syrian hamster prion protein SHaPrP90-232, whose in vitro transition from the predominantly a-helical isoform to β-sheet rich oligomeric structures was also investigated by FTIR spectroscopy.

  4. Investigating structural changes induced by nucleotide binding to RecA using difference FTIR.

    OpenAIRE

    Butler, Blaine C; Hanchett, Ross H; Rafailov, Helena; MacDonald, Gina

    2002-01-01

    Nucleotide binding to RecA results in either the high-DNA affinity form (Adenosine 5'-triphosphate (ATP)-bound) or the more inactive protein conformation associated with a lower affinity for DNA (Adenosine 5'-diphosphate (ADP)-bound). Many of the key structural differences between the RecA-ATP and RecA-ADP bound forms have yet to be elucidated. We have used caged-nucleotides and difference FTIR in efforts to obtain a comprehensive understanding of the molecular changes induced by nucleotide b...

  5. Micro- and nanoscale structures of mesiodens dentin: Combined study of FTIR and SAXS/WAXS techniques.

    Science.gov (United States)

    Akgun, Ozlem Marti; Bayari, Sevgi Haman; Ide, Semra; Polat, Günseli Guven; Kalkhoran, Ilghar Orujalipoor

    2015-01-01

    A mesiodens is the most common type of supernumerary tooth present in conjunction to normal dentition. A mesiodens may commonly occur in the central region of the upper or lower jaw. A mesiodens is different from normal teeth in terms of structure and shape. The aim of this study is to evaluate the micro- and nanoscale structural properties of mesiodens dentin by combined small- and wide-angle X-ray scattering (SAXS/WAXS) and Fourier transform infrared (FTIR) spectroscopy. Five freshly extracted, noncarious mesiodens and five normal dentin disks prepared from human incisor teeth were compared. Using FTIR, the phosphate-to-amide I, carbonate-to-phosphate, and carbonate-to-amide I band area ratios and the crystallinity index were quantified. SAXS/WAXS were used to study the nanostructure of mesiodens. An increase in the mineral content in the mesiodens dentin with respect to the normal group was found. Crystallinity was also significantly increased and the protein content decreased in the mesiodens dentin compared with that of normal dentin. SAXS/WAXS results revealed that mesiodens dentin has a more calcified tissue. Further, SAXS analysis revealed a nonuniform distribution of dentin fibrils in mesiodens. © 2014 Wiley Periodicals, Inc.

  6. The Structure Of Intact Side Tissue Loss Based On FTIR Spectroscopic Measurements

    Science.gov (United States)

    Hussain, N.; Al-Hadithi, K. O.; Jaafar, M. S.

    2009-09-01

    Laser applications in dentistry were strongly evolved during the last three decades. Among those applications are laser ablation of dental hard tissue, caries inhibition treatments by localized surface heating, and surface conditioning for bonding. In addition, infra-red lasers are ideally suited for the selective and precise removal of carious dental hard tissue while minimizing the healthy tissue loss. In the present study we applied laser spectroscopy technique FTIR for the study of the structure of intact side tissue of teeth. The aim of the recent work is to study the effect of race and sex (genealogy) on the structure of intact side tissue loss. Our sample consists of twenty Malay females' teeth where the FTIR has been applied. The data show a decrease in the amounts of main substances (like Hydroxyapatite crystals ([Ca5(PO4)3(OH)4], CaF2) than those in healthy teeth. The measured spectra represent the enamel with the characteristic peaks due to the phosphate group in carbonated, hydroxyapatite at 1000 cm-1 and two small peaks near 1500 cm-1 due to the carbonate group. The data explains the effect of the several factors on the intact side tissue loss.

  7. Molecular structure of human aortic valve by μSR- FTIR microscopy

    Science.gov (United States)

    Borkowska, Anna M.; Nowakowski, Michał; Lis, Grzegorz J.; Wehbe, Katia; Cinque, Gianfelice; Kwiatek, Wojciech M.

    2017-11-01

    Aortic valve is a part of the heart most frequently affected by pathological processes in humans what constitute a very serious health problem. Therefore, studies of morphology and molecular microstructure of the AV are needed. μSR- FTIR spectroscopy and microscopy represent unique tools to study chemical composition of the tissue and to identify spectroscopic markers characteristic for structural and functional features. Normal AV reveals a multi-layered structure and the compositional and structural changes within particular layers may trigger degenerative processes within the valve. Thus, deep insight into the structure of the valve to understand pathological processes occurring in AV is needed. In order to identify differences between three layers of human AV, tissue sections of macroscopically normal AV were studied using μSR- FTIR spectroscopy in combination with histological and histochemical stainings. Tissue sections deposited onto CaF2 substrates were mapped and representative set of IR spectra collected from fibrosa, spongiosa and ventricularis were analysed by Principal Component Analysis (PCA) in the spectral range between 1850-1000 cm-1 and 3050-2750 cm-1. PCA revealed a layered molecular structure of the valve and it was possible to identify IR bands associated to different tissue parts. Spongiosa layer was well differentiated from other two layers mainly based on IR bands characteristic for the distribution of glycosaminoglycans (GAGs) in the tissue - like 1170 cm-1 (υas(C-O-S)) and 1380 cm-1 (acetyl amino group). Additionally, it was distinguished from fibrosa and ventricularis based on 1085 cm-1 and 1240 cm-1 bands characteristic for GAGs and for carbohydrates- ν(C-O) and ν(C-O-C) respectively and nucleic acids -νsym(PO2-) and νasym(PO2-) respectively, which were less specific for this layer. The use of μSR- FTIR spectroscopy demonstrated co-localization of GAGs and lipids in spongiosa layer what may indicate their contribution in the very

  8. Synthesis, structures and theoretical investigation of

    Science.gov (United States)

    Weigend; Wirth; Ahlrichs; Fenske

    2000-02-04

    The silylated derivative of thiophosphoric acid (S)P(SSiMe3)3 is used as a convenient starting compound for the synthesis of multinuclear Cu and Au cluster complexes. (S)P(SSiMe3)3 reacts with CuCI/PPh3 and [AuCClPPh3] to give the following compounds: [Cu4(P2S6)(PPh3)4] (1), [Cu6(P2S6)Cl2-(PPh3)6] (2) and [Au4(P2S6)(PPh3)4](3). According to X-ray structure determination, these compounds contain P2S6(4-) ions, in which S atoms act as ligands for Cu+ and Au+ ions. Although 1 and 3 have the same stoichiometry, bonding of the metal ions to the P2S6 skeleton displays small but remarkable differences. Au is twofold coordinated, whereas Cu shows a threefold coordination. Ab initio calculations have been carried out to rationalise these structural differences. The theoretical treatment of the corresponding Ag compound indicates the latter to be less stable.

  9. FTIR spectroscopy structural analysis of the interaction between Lactobacillus kefir S-layers and metal ions

    Science.gov (United States)

    Gerbino, E.; Mobili, P.; Tymczyszyn, E.; Fausto, R.; Gómez-Zavaglia, A.

    2011-02-01

    FTIR spectroscopy was used to structurally characterize the interaction of S-layer proteins extracted from two strains of Lactobacillus kefir (the aggregating CIDCA 8348 and the non-aggregating JCM 5818) with metal ions (Cd +2, Zn +2, Pb +2 and Ni +2). The infrared spectra indicate that the metal/protein interaction occurs mainly through the carboxylate groups of the side chains of Asp and Glut residues, with some contribution of the NH groups belonging to the peptide backbone. The frequency separation between the νCOO - anti-symmetric and symmetric stretching vibrations in the spectra of the S-layers in presence of the metal ions was found to be ca. 190 cm -1 for S-layer CIDCA 8348 and ca. 170 cm -1 for JCM 5818, denoting an unidentate coordination in both cases. Changes in the secondary structures of the S-layers induced by the interaction with the metal ions were also noticed: a general trend to increase the amount of β-sheet structures and to reduce the amount of α-helices was observed. These changes allow the proteins to adjust their structure to the presence of the metal ions at minimum energy expense, and accordingly, these adjustments were found to be more important for the bigger ions.

  10. Diffusion of Carbon Dioxide in Cordierite-like Structures: a FTIR Imaging Approach

    Science.gov (United States)

    Radica, F.; Bellatreccia, F.; Della Ventura, G.; Freda, C.; Cinque, G.; Cestelli Guidi, M.

    2013-12-01

    In the last decades microporous and mesoporous minerals have been recognized to be very important materials from both a geological and a technological viewpoint. In this context, cordierite plays a key role since it represents the only case of a widespread microporous mineral able to trap significant amounts of molecular H2O and CO2 [1] under extreme geological conditions, spanning from the amphibolite facies to ultra-high temperature metamorphism to crustal anatexis [2]. The analysis of volatiles in cordierite can be a very useful tool to define the composition of coexisting fluids during its formation, thus a deeper knowledge of their diffusion mechanism through the structure is crucial in petrologic studies. However, it may have significant implications on technological issues such as the design of new strategies for the permanent sequestration of atmospheric CO2. The incorporation of CO2 into cordierite has been studied by several authors [1, 3], who pointed out the extreme difficulty to reach the sample saturation and homogenization, implying that in experimental studies knowledge of the actual distribution of the volatile molecules in the run samples is crucial to derive any scientific conclusion. In this work, we addressed this problem using FTIR imaging. Our experiments were carried out in tandem on natural cordierite and synthetic CO2-free beryl, a mineral which is isostructural with cordierite. All samples were treated in CO2-saturated atmosphere at different pressure, temperature and time conditions using a non end-load piston-cylinder apparatus at INGV. The run products were oriented using a spindle stage, cut and doubly polished, and analyzed using polarized micro-FTIR spectroscopy at INFN-LNF in order to study the distribution across the sample and quantify the CO2 content. Preliminary data show that both pressure and time play a major role on the diffusion of gaseous CO2 in both cordierite and beryl, whereas the effect of temperature is less

  11. Theoretical molecular structure, vibrational frequencies and NMR ...

    African Journals Online (AJOL)

    Theoretical results have been successfully compared with available experimental data in the literature. Regarding the calculations, 2mpe-4bb prefers enol-imine form and DFT method is superior to HF approach except for predicting bond lengths. KEY WORDS: Schiff bases, Normal mode frequencies, HF, DFT, NMR. Bull.

  12. A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Ye Zou

    2014-06-01

    Full Text Available Second derivative and Fourier self-deconvolution (FSD are two commonly used techniques to resolve the overlapped component peaks from the often featureless amide I band in Fourier transform infrared (FTIR curve-fitting approach for protein secondary structural analysis. Yet, the reliability of these two techniques is greatly affected by the omnipresent water vapor in the atmosphere. Several criteria are currently in use as quality controls to ensure the protein absorption spectrum is negligibly affected by water vapor interference. In this study, through a second derivative study of liquid water, we first argue that the previously established criteria cannot guarantee a reliable evaluation of water vapor interference due to a phenomenon that we refer to as sample’s absorbance-dependent water vapor interference. Then, through a comparative study of protein and liquid water, we show that a protein absorption spectrum can still be significantly affected by water vapor interference even though it satisfies the established criteria. At last, we propose to use the comparison between the second derivative spectra of protein and liquid water as a new criterion to better evaluate water vapor interference for more reliable second derivative and FSD treatments on the protein amide I band.

  13. Spectroscopic (NMR, UV, FT-IR and FT-Raman) analysis and theoretical investigation of nicotinamide N-oxide with density functional theory.

    Science.gov (United States)

    Atac, Ahmet; Karabacak, Mehmet; Kose, Etem; Karaca, Caglar

    2011-12-01

    The spectroscopic properties of the nicotinamide N-oxide (abbreviated as NANO, C(6)H(6)N(2)O(2)) were examined by FT-IR, FT-Raman, NMR and UV techniques. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. The (1)H and (13)C NMR spectra were recorded in DMSO. The UV absorption spectrum of the compound that dissolved in water was recorded in the range of 200-800 nm. The structural and spectroscopic data of the molecule in the ground state were calculated by using Density Functional Theory (DFT) employing B3LYP methods with the 6-311++G(d,p) basis set. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The optimized structure of compound was interpreted and compared with the reported experimental values. The observed vibrational wavenumbers, absorption wavelengths and chemical shifts were compared with calculated values. As a result, the optimized geometry and calculated spectroscopic data show a good agreement with the experimental results. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Experimental and theoretical studies of (FT-IR, FT-Raman, UV-Visible and DFT) 4-(6-methoxynaphthalen-2-yl) butan-2-one.

    Science.gov (United States)

    Govindasamy, P; Gunasekaran, S

    2015-01-01

    In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 4000-50 cm(-1) and 4000-450 cm(-1) respectively for 4-(6-methoxynaphthalen-2-yl) butan-2-one (abbreviated as 4MNBO) molecule. Theoretical calculations were performed by density functional theory (DFT/B3LYP) method using 6-311G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and calculated wavenumber value of most of the fundamentals were very small. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The UV-Vis spectrum was recorded in the methanol solution. The energy, wavelength and oscillator's strength were calculated by Time Dependent Density Functional Theory (TD-DFT) and matched to the experimental findings. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Thermodynamic properties of 4MNBO at different temperature have been calculated. The molecular electrostatic potential surface (MESP) and Frontier molecular orbital's (FMO's) analysis were investigated using theoretical calculations. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Theoretical investigation on structural evolution, energetic stability ...

    Indian Academy of Sciences (India)

    Abstract. We systematically studied the geometrical structures, relative stabilities, electronic properties and chemical hardness of AunCd (n=1–12) clusters based on the framework of the density functional theory using relativistic all-electron methods. Low-lying energy structures include two-dimensional and three- ...

  16. Synthesis, crystal structure, theoretical study and luminescence ...

    Indian Academy of Sciences (India)

    phenanthroline) has been synthesized and characterized by elemental analysis, infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray single crystal analysis and fluorescent analysis. Its crystal structure is monoclinic with space group 2/ and ...

  17. Study on the variations of molecular structures of some biomolecules induced by free electron laser using FTIR spectroscopy

    Science.gov (United States)

    Yang, Limin; Xu, Yizhuang; Su, Yunlan; Wu, Jinguang; Zhao, Kui; Wang, Mingkai; Xu, Jinqiang; Dai, Zhiping; Chen, Jia'er

    2007-05-01

    In this study, free electron laser (FEL) with selective wavelength was used to induce structure changes of biomolecules, which were characterized by FTIR spectroscopy. For understanding of the interactions between FEL and biomolecules as well as biological tissues, the biomolecules investigated are ATP, ADP, AMP, t-RNA, D-ribose and the complex of SmCl 3- D-ribose. Their FTIR spectra before and after irradiation of FEL show molecular structure variations of the samples after irradiation of FEL, especially the rearrangement of their hydrogen bond networks. Along with the various irradiation wavelengths, irradiation time and molecular structures, the changes after irradiation are different for these molecules. In the FTIR spectra after irradiation, the phenomenon that the bands split into several peaks indicates the existence of several structures, conformations and configurations, which may be prompted by multiple photons process induced by FEL. After irradiation, the changes in their IR spectra indicate the occurrence of stable or metastable states of the molecules after irradiation, which illustrated that IR spectroscopy is a sensitive probe of molecular structure and provides us a method to detect the information related to the mechanism of the irradiation process.

  18. Synthesis, crystal structure, theoretical study and luminescence ...

    Indian Academy of Sciences (India)

    performed on complex 1 to rationalize its experimental absorption spectra. Complex 1 exhibits luminescence in EtOH ... potential applications in biological systems like, devel- opment of structural and functional models for ... to react with [WOnS4−n] (n = 0-2).11,12 These reactions result in the formation of a large number of ...

  19. Theoretical Studies of Structure, Spectroscopy, and Properties of a New Hydrazine Derivative

    Directory of Open Access Journals (Sweden)

    Hajar Sahebalzamani

    2013-01-01

    Full Text Available We will report a combined experimental and theoretical study on molecular structure, vibrational spectra, and energies of (E-1-(2,4-dinitrophenyl-2-[(4-methylphenylmethylidene]hydrazine (1. The molecular geometry and vibrational frequencies and energies in the ground state are calculated by using HF and DFT levels of theory with 6-311G basis sets. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. The harmonic vibrational frequencies were calculated, and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar-type spectrograms.

  20. FT-IR, Raman and DFT studies on the vibrational spectra of 2,2-bis ...

    African Journals Online (AJOL)

    propane (baep) were examined both experimentally and theoretically including FT-IR and Raman spectroscopic methods. Among the possible structural configurations, 30 of them were handled in the framework of this study. The structural ...

  1. A combined experimental and theoretical studies on FT-IR, FT-Raman and UV-vis spectra of 2-chloro-3-quinolinecarboxaldehyde.

    Science.gov (United States)

    Prasad, M V S; Udaya Sri, N; Veeraiah, V

    2015-09-05

    In the present study, the FT-IR and FT-Raman spectra of 2-chloro-3-quinolinecarboxaldehyde (2Cl3QC) have been recorded in the region 4000-400 and 3500-50 cm(-1), respectively. The fundamental modes of vibrational frequencies of 2Cl3QC are assigned. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of density functional theory (DFT) gradient calculations with complete relaxation in the potential energy surface using 6-31G(d,p) basis set. The vibrational frequencies which were determined experimentally from the spectral data are compared with those obtained theoretically from DFT calculations. A close agreement was achieved between the observed and calculated frequencies by refinement of the scale factors. The infrared and Raman spectra were also predicted from the calculated intensities. Thermodynamic properties like entropy, heat capacity, zero point energy, have been calculated for the molecule. The predicted first hyperpolarizability also shows that the molecule might have a reasonably good non-linear optical (NLO) behavior. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization have been analyzed using natural bond orbitals (NBO) analysis. The results show that charge in electron density (ED) in the π(∗) antibonding orbitals and E((2)) energies confirms the occurrence of ICT (intra-molecular charge transfer) within the molecule. UV-visible spectrum of the title molecule has also been calculated using TD-DFT/CAM-B3LYP/6-31G(d,p) method. The calculated energy and oscillator strength almost exactly reproduces reported experimental data. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Theoretical study of electron transport throughout some molecular structures

    Science.gov (United States)

    Abbas, Mohammed A. A.; Hanoon, Falah H.; Al-Badry, Lafy F.

    2017-11-01

    The present work is a theoretical study of the electronic properties of some molecular structures. The system that takes into account in the study is left lead-donor-molecule-acceptor-right lead. The molecule, such as (phenyl, biphenyl, triphenyl, naphthalene, anthracene, and phenanthrene), is threaded by magnetic flux. This work contains two parts. First is computing density of states of the molecular structures as a closed system by density functional theory (DFT). Second is calculating the transmission probability and electric current of such molecular structures as an open system by steady-state theoretical model. Furthermore, the most important effects, taking into consideration are quantum interference, magnetic flux, and interface structure. Our results show that the connection of the molecule to the two leads, the number of rings, the magnetic flux, and the geometrical structure of the molecule play an important role in determining the energy gap of molecular structures.

  3. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.

    Science.gov (United States)

    Świsłocka, Renata

    2013-01-01

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Spectroscopic [FT-IR and FT-Raman] and theoretical [UV-Visible and NMR] analysis on α-Methylstyrene by DFT calculations

    Science.gov (United States)

    Karthikeyan, N.; Joseph Prince, J.; Ramalingam, S.; Periandy, S.

    2015-05-01

    In the present research work, the FT-IR, FT-Raman and 13C and 1H NMR spectra of the α-Methylstyrene were recorded. The observed fundamental frequencies in finger print as well as functional group regions were assigned according to their uniqueness region. The Gaussian computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The impact of the presence of vinyl group in phenyl structure of the compound is investigated. The modified vibrational pattern of the molecule associated vinyl group was analyzed. Moreover, 13C NMR and 1H NMR were calculated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts linked to TMS were compared. A study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies were carried out. The kubo gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The NLO properties related to Polarizability and hyperpolarizability based on the finite-field approach were also discussed.

  5. FT-IR and Raman spectroscopies determine structural changes of tilapia fish protein isolate and surimi under different comminution conditions.

    Science.gov (United States)

    Kobayashi, Yuka; Mayer, Steven G; Park, Jae W

    2017-07-01

    Tilapia proteins refined by pH shift and water washing were chopped under various comminution conditions and their structural changes were investigated using Fourier transform infrared (FT-IR) and Raman spectroscopies. Both techniques revealed the degree of unfolding in protein structure increased when fish protein isolate (FPI) and surimi were chopped at 25°C for 18min compared to samples chopped at 5°C for 6min. Results indicated both hydrophobic interactions and disulfide bonds were significantly enhanced during gelation. FPI and surimi gels prepared at 25°C for 18min exhibited higher β-sheet contents and more chemical bonds such as hydrophobic interactions and disulfide bonds than those at 5°C for 6min. Results suggested that controlling comminution is important to improve gel qualities in FPI and surimi from tropical fish like tilapia. Moreover, FT-IR and Raman spectroscopies are useful complementary tools for elucidating the change in the structure of protein during comminution and gelation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. [Research on structure and UV curing behaviors of novel cardanol-based unsaturated resins using FTIR spectrum analysis method].

    Science.gov (United States)

    Li, Shou-Hai; Yang, Xue-Juan; Li, Mei; Huang, Kun; Xia, Jian-Ling

    2013-10-01

    Two dissimilar cardanol-based unsaturated resin monomers were prepared via simple ring-opening and etherification reaction by utilizing the reactivity between phenolic hydroxyl and epoxy group with the aid of cardanol as raw material. The transformations of different groups were characterized using Fourier transform infrared (FTIR) during the synthesis process, the resin monomers' structure was further analyzed using the 1H-nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC), and the UV curing behaviors of resin monomers were studied by means of FTIR method. In addition, the thermal stability of UV cured resin monomers were also tested by thermogravimetric analysis (TGA). The molecular structure analysis demonstrated that these two target products were successfully synthesized. UV curing behaviors analysis showed that the prepared cardanol-based unsaturated resin monomers could reach ultimate curing level within 30 s. TGA results showed that the molecular structure and the content of double bond had critical influence on their thermal stability. The main initial thermal decomposition temperature of these two cured resin monomers was all above 350 degrees C.

  7. Dissecting the mechanism of Epac activation via hydrogen-deuterium exchange FT-IR and structural modeling.

    Science.gov (United States)

    Yu, Shaoning; Fan, Fenghui; Flores, Samuel C; Mei, Fang; Cheng, Xiaodong

    2006-12-26

    Exchange proteins directly activated by cAMP (Epac) make up a family of cAMP binding domain-containing proteins that play important roles in mediating the effects of cAMP through the activation of downstream small GTPases, Ras-proximate proteins. To delineate the mechanism of Epac activation, we probed the conformation and structural dynamics of Epac using amide hydrogen-deuterium (H-D) exchange coupled with Fourier transform infrared spectroscopy (FT-IR) and structural modeling. Our studies show that unlike that of cAMP-dependent protein kinase (PKA), the classic intracellular cAMP receptor, binding of cAMP to Epac does not induce significant changes in overall secondary structure and structural dynamics, as measured by FT-IR and the rate of H-D exchange, respectively. These results suggest that Epac activation does not involve significant changes in the amount of exposed surface areas as in the case of PKA activation, and conformational changes induced by cAMP in Epac are most likely confined to small local regions. Homology modeling and comparative structural analyses of the CBDs of Epac and PKA lead us to propose a model of Epac activation. On the basis of our model, Epac activation by cAMP employs the same underlying structural principal utilized by PKA, although the detailed structural and conformational changes associated with Epac and PKA activation are significantly different. In addition, we predict that during Epac activation the first beta-strand of the switchboard switches its conformation to a alpha-helix, which folds back to the beta-barrel core of the CBD and interacts directly with cAMP to form the base of the cAMP-binding pocket.

  8. The Theoretical Foundations of Structural Changes in Economy

    Directory of Open Access Journals (Sweden)

    Khaustova Viktoriia Ye.

    2017-12-01

    Full Text Available The article is aimed at defining the theoretical foundations of structural changes in economy. It has been proved that structural policy of the State is one of the main directions influencing the structure of economy, balancing its proportions, and ensuring progressive development. The components of structural policy have been defined. Genesis of scientific directions of researching the structure of economy was considered. The interpretation of the concept of «structure of economy» in the works of scientists was studied. The classification of particular structures of the national industrial complex was considered. It has been proved that the main role in the analysis of structural changes should be given to the structure of economy (of industrial complex, according to the types of economic activity. The interpretations of the concepts of «structural transformations», «structural shifts», «structural changes», «structural crisis» in the economy have been clarified. The functions of structural crises have been considered. The dynamics of changes in structural shifts were researched. The classification of structural shifts in the economy was considered. An interpretation of progressive structural changes has been suggested.

  9. Crystal structure and theoretical studies on quinoline phosphate

    Science.gov (United States)

    Ben Issa, T.; Ghalla, H.; Marzougui, S.; Benhamada, L.

    2017-12-01

    The crystal structure of (C9H7N) H3PO4 (QP) was determined from single crystals obtained by slow evaporation methods (space group Pī; a = 7.5508(3) Å, b = 7.9705(3) Å, c = 8.6849(3) Å; α = 77.3725(18)°, β = 82.6225(19)°, γ = 74.9829(19)°). The crystal structure of QP is built up from infinite hydrogen bonding inorganic chains of (H3PO4)n lay parallel to the an axis, which are also connected to the quinoline rings through hydrogen bonds in a 3D arrangement. The structure was examined through atoms in molecules (AIM) topological and Hirshfeld surface (HS) analyses and its molecular structure optimized by theoretical density functional (DFT) calculations. The QP observed IR absorptions between 4000 and 400 cm-1 were assigned on the basis of the calculated theoretical vibrational modes.

  10. Generation, structure and reactivity of arynes: A theoretical study

    Indian Academy of Sciences (India)

    Generation, structure and reactivity of arynes: A theoretical study. PETER G S DKHAR and R H DUNCAN LYNGDOH*. Department of Chemistry, North-Eastern Hill University, Bijni Complex,. Shillong 793 003, India. MS received 20 September 1999; revised 14 February 2000. Abstract. The semiempirical AM1 SCF-MO ...

  11. THEORETICAL AND EXPERIMENTAL STUDY OF STRUCTURES SUBJECTED TO EARTHQUAKES

    Energy Technology Data Exchange (ETDEWEB)

    Soubirou, A.

    1967-12-31

    The object of the study was the investigation of the behaviour of structures subject to earthquakes. After .describing and analysing seismic movements, useful concepts for earthquake-proofing structures are lintroduced. Then, the dynamic behaviour of systems with n degrees of freedom was studied in order to evolve the theoretical computation of seismic behaviour, a typical application being reticulated structures. The next stage was showing the computational procedure for seismic spectra and the natural frequencies of buildings, an attempt being made to define earthquake-proofing criteria for a special type of reinforced-concrete construction. . The last matter dealt with is elastoplastic behaviour of structures, a study of increasingly growing importance.

  12. Theoretical structural and vibrational study of 5-trifluoromethyluracil. A comparison with uracil

    Energy Technology Data Exchange (ETDEWEB)

    Rudyk, Roxana; Ramos, María E.; Checa, María A.; Brandán, Silvia A. [Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471,(4000), San Miguel de Tucumán, Tucum and #x00E1 (Argentina); Chamorro, Eduardo E. [Facultad de Ciencias Exactas, Universidad Andrés Bello, Avda. República 275, 8370146, Santiago (Chile)

    2014-10-06

    In the present work, a comparative study on the structural and vibrational properties of the 5-trifluoromethyluracil (TFMU) derivative with those corresponding to uracil in gas and aqueous solution phases was performed combining the available H{sup 1}-NMR, C{sup 13}-NMR, F{sup 19}-NMR and FTIR spectra with Density Functional Theory (DFT) calculations. Three stable conformers were theoretically determined in both media by using the hybrid B3LYP/6-31G* method. The solvent effects were simulated by means of the self-consistent reaction field (SCRF) method employing the integral equation formalism variant (IEFPCM). Complete assignments of the vibrational spectra in both phases were performed combining the internal coordinates analysis and the DFT calculations with the Scaled Quantum Mechanics Force Field (SQMFF) methodology. The atomic charges, bond orders, solvation energies, dipole moments, molecular electrostatic potentials and force constants parameters were calculated for the three conformers of TFMU in gas phase and aqueous solution.

  13. Sensing the Structural Differences in Cellulose from Apple and Bacterial Cell Wall Materials by Raman and FT-IR Spectroscopy

    Science.gov (United States)

    Szymańska-Chargot, Monika; Cybulska, Justyna; Zdunek, Artur

    2011-01-01

    Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the Iβ content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (XCRAMAN%) varied from −25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose Iβ. However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm−1. Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls. PMID:22163913

  14. Fourier transform infrared (FT-IR study on cyanide induced biochemical and structural changes in rat sperm

    Directory of Open Access Journals (Sweden)

    Shiddappa Mallappa Shivanoor

    2015-01-01

    Full Text Available In the recent years, great attention had been focused on cyanide toxicity because of its widespread use in industries and considered to be a ubiquitous pollutant in the environment. Therefore, the current study aimed to evaluate the toxic effect of cyanide on rat sperms at molecular level by using FT-IR technique. For this purpose, rats were randomly divided into four groups and treated with 0.0, 0.64, 1.2 and 3.2 mg kg−1 body weight (BW for the period of 90 days. The group treated with lower dose (0.64 mg kg−1 BW showed an insignificant change in all the peaks, except the peaks assigned to olefinic CH, CH2 asymmetric and CH2 symmetric stretching vibration in the lipids. While, the groups treated with higher doses (1.2 and 3.2 mg kg−1 BW showed the significant decrease in the area under the peaks corresponds to different bio-molecules. In addition, spectral second derivative analysis showed the significant alteration in α-helix, turns, β-sheet, aggregated β-sheet and random coil structures in the proteins. In conclusion, the selected higher dosage of cyanide had caused significant decrease in the biochemical composition of rat sperms along with structural changes in the proteins. The FT-IR technique is an excellent tool used for the analysis of oxidative damage in the sperms.

  15. Spectroscopic [FT-IR and FT-Raman] and theoretical [UV-Visible and NMR] analysis on α-Methylstyrene by DFT calculations.

    Science.gov (United States)

    Karthikeyan, N; Joseph Prince, J; Ramalingam, S; Periandy, S

    2015-05-15

    In the present research work, the FT-IR, FT-Raman and (13)C and (1)H NMR spectra of the α-Methylstyrene were recorded. The observed fundamental frequencies in finger print as well as functional group regions were assigned according to their uniqueness region. The Gaussian computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The impact of the presence of vinyl group in phenyl structure of the compound is investigated. The modified vibrational pattern of the molecule associated vinyl group was analyzed. Moreover, (13)C NMR and (1)H NMR were calculated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts linked to TMS were compared. A study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies were carried out. The kubo gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The NLO properties related to Polarizability and hyperpolarizability based on the finite-field approach were also discussed. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  16. Tyranny, freedom and social structure: escaping our theoretical prisons.

    Science.gov (United States)

    Turner, John C

    2006-03-01

    Reicher and Haslam's (2006) BBC prison study undermines the idea that people passively accept and enact social roles. In this commentary, I point out that this idea is an example of Moscovici's (1976) conformity bias and a wider stability bias in social psychological theorizing. In many key areas, the science prefers analyses that explain how and why social structures, intergroup and power relations, personalities and beliefs maintain and reproduce themselves, and indeed cannot be changed, rather than how and why society constantly generates forces for social change from within itself. This bias distorts reality and produces ideas of limited theoretical or practical power. Human psychology does not make us prisoners of social structure. It makes us capable of collective action to change social structures and in turn re-fashion our identities, roles, personalities and beliefs. Society is not a psychological prison but a means of expanding human possibilities. A reorientation of theoretical emphasis is overdue.

  17. Structural, spectroscopic (FT-IR, NMR, UV-visible), nonlinear optical (NLO), cytotoxic and molecular docking studies of 4-nitro-isonitrosoacetophenone (ninapH) by DFT method

    Science.gov (United States)

    Kucuk, Ilhan; Kaya, Yunus; Kaya, A. Asli

    2017-07-01

    (4-Nitro-phenyl)-oxo-acetaldehyde oxime (ninapH) is a type of oxime, which has a oxime and α-carbonyl groups. This molecule has been synthesized from literature procedure. The structural properties and conformational behaviors were examined using the density functional theory (DFT) with the B3LYP method combined with the 6-311++G(d,p) basis set. As a result of the conformational studies, the most stable conformer was determined, and then this molecule was optimized with the same basis set. Comprehensive theoretical and experimental structural studies on the molecule have been carried out by FT-IR, NMR and UV-vis spectrometry. The calculated HOMO and LUMO energies show that charge transfer within the molecule. The first order hyperpolarizability and molecular electrostatic potential (MEP) were also performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the ninapH have been calculated at different temperatures, 100-1000 K. In addition, the molecular docking studies have been performed with DNA and protein structures (downloaded from Protein Data Bank).

  18. FTIR study of secondary structure of bovine serum albumin and ovalbumin

    International Nuclear Information System (INIS)

    Abrosimova, K V; Shulenina, O V; Paston, S V

    2016-01-01

    Proteins structure is the critical factor for their functioning. Fourier transform infrared spectroscopy provides a possibility to obtain information about secondary structure of proteins in different states and also in a whole biological samples. Infrared spectra of egg white from the untreated and hard-boiled hen's egg, and also of chicken ovalbumin and bovine serum albumin in lyophilic form and in aqueous solution were studied. Lyophilization of investigated globular proteins is accompanied by the decrease of a-helix structures and the increase in amount of intermolecular β-sheets. Analysis of infrared spectrum of egg white allowed to make an estimation of OVA secondary structure and to observe α-to-β structural transformation as a result of the heat denaturation. (paper)

  19. Molecular structure, vibrational spectra (FTIR and FT Raman) and natural bond orbital analysis of 4-Aminomethylpiperidine: DFT study.

    Science.gov (United States)

    Mahalakshmi, G; Balachandran, V

    2014-10-15

    The FT-IR and FT-Raman spectra of 4-Aminomethylpiperidine have been recorded using Perkin Elmer Spectrophotometer and Nexus 670 spectrophotometer. The equilibrium geometrical parameters, various bonding features, the vibrational wavenumbers, the infrared intensities and the Raman scattering activities were calculated using Hartree-Fock and density functional method (B3LYP) with 6-311+G(d,p) basis set. Detailed interpretations of the vibrational spectra have been carried out with the aid of the normal coordinate analysis. The spectroscopic and natural bonds orbital (NBO) analysis confirms the occurrence of intra molecular hydrogen bonds, electron delocalization and steric effects. The changes in electron density in the global minimum and in the energy of hyperconjugative interactions of 4-Aminomethylpiperidine (4AMP) were calculated. The theoretical UV-Visible spectrum of the compound was computed in the region 200-400nm by time-dependent TD-DFT approach. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (μ) and polarizability (α), anisotropy polarizability (Δα) and hyperpolarizability (β) of the molecule have been reported. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Information-theoretical noninvasive damage detection in bridge structures

    Science.gov (United States)

    Sudu Ambegedara, Amila; Sun, Jie; Janoyan, Kerop; Bollt, Erik

    2016-11-01

    Damage detection of mechanical structures such as bridges is an important research problem in civil engineering. Using spatially distributed sensor time series data collected from a recent experiment on a local bridge in Upper State New York, we study noninvasive damage detection using information-theoretical methods. Several findings are in order. First, the time series data, which represent accelerations measured at the sensors, more closely follow Laplace distribution than normal distribution, allowing us to develop parameter estimators for various information-theoretic measures such as entropy and mutual information. Second, as damage is introduced by the removal of bolts of the first diaphragm connection, the interaction between spatially nearby sensors as measured by mutual information becomes weaker, suggesting that the bridge is "loosened." Finally, using a proposed optimal mutual information interaction procedure to prune away indirect interactions, we found that the primary direction of interaction or influence aligns with the traffic direction on the bridge even after damaging the bridge.

  1. Change in Glutenin Macropolymer Secondary Structure in Wheat Sourdough Fermentation by FTIR.

    Science.gov (United States)

    Wang, Jinshui; Yue, Yuanyuan; Liu, Tiantian; Zhang, Bin; Wang, Zhenlei; Zhang, Changfu

    2017-06-01

    Wheat sourdough was prepared by fermentation with Lactobacillus plantarum M616 and yeast in the present study. The change in secondary structure of glutenin macropolymer (GMP) in wheat sourdough fermentation for 4 and 12 h was determined using Fourier transform infrared spectroscopy, and then the resultant spectra were Fourier self-deconvoluted of the amide I band in the region from 1600 to 1700 cm -1 . Significant different spectra especially in the amide I band for GMP from sourdough fermented with L. plantarum M616 (SL) and with L. plantarum M616 and yeast (SLY) were found in respect of control dough (CK), dough with acids (SA), and sourdough fermented with yeast (SY) at 4 and 12 h of fermentation. The loss of α-helix structure in SL, SLY, and SA samples was noticed during fermentation. Compared with CK and SY, SL, SLY, and SA samples showed significant decrease (p fermentation. In addition, β-turns in SL sourdough decrease, and the relative areas of random coil increase significantly (p fermentation. The modified secondary structure of GMP makes more sensitive to proteolysis by means of cereal enzymes.

  2. Structure of halo nuclei - overview of theoretical status

    International Nuclear Information System (INIS)

    Al-Khalili, J.S.

    2003-01-01

    The past decade has seen an explosion of theoretical interest in the structure and dynamics of halo nuclei. Their basic defining features of weak binding and large radial extent due to the extended tail in their densities is now well-described within few-body models. This has led to impressive advances in few-body reaction theories which crucially take into account this few-body nature. This paper will review some of the recent advances in both structure and reaction studies, and will focus on the issues currently of interest along with possible directions for future advances. On the structure side, improvements to few-body models are being explored to take into account the role of antisymmetrization more accurately and the importance of core polarization and excitation. The successes of fully microscopic approaches will also be reviewed. (orig.)

  3. Theoretical temperature model with experimental validation for CLIC Accelerating Structures

    CERN Document Server

    AUTHOR|(CDS)2126138; Vamvakas, Alex; Alme, Johan

    Micron level stability of the Compact Linear Collider (CLIC) components is one of the main requirements to meet the luminosity goal for the future $48 \\,km$ long underground linear accelerator. The radio frequency (RF) power used for beam acceleration causes heat generation within the aligned structures, resulting in mechanical movements and structural deformations. A dedicated control of the air- and water- cooling system in the tunnel is therefore crucial to improve alignment accuracy. This thesis investigates the thermo-mechanical behavior of the CLIC Accelerating Structure (AS). In CLIC, the AS must be aligned to a precision of $10\\,\\mu m$. The thesis shows that a relatively simple theoretical model can be used within reasonable accuracy to predict the temperature response of an AS as a function of the applied RF power. During failure scenarios or maintenance interventions, the RF power is turned off resulting in no heat dissipation and decrease in the overall temperature of the components. The theoretica...

  4. Combined experimental and quantum chemical studies on spectroscopic (FT-IR, FT-Raman, UV-Vis, and NMR) and structural characteristics of quinoline-5-carboxaldehyde

    Science.gov (United States)

    Kumru, Mustafa; Altun, Ahmet; Kocademir, Mustafa; Küçük, Vesile; Bardakçı, Tayyibe; Şaşmaz, İbrahim

    2016-12-01

    Comparative experimental and theoretical studies have been performed on the structure and spectral (FT-IR, FT-Raman, UV-Vis and NMR) features of quinoline-5-carboxaldehyde. Quantum chemical calculations have been carried out at Hartree-Fock and density functional B3LYP levels with the triple-zeta 6-311++G** basis set. Two stable conformers of quinoline-5-carboxaldehyde arising from the orientation of the carboxaldehyde moiety have been located at the room temperature. The energetic separation of these conformers is as small as 2.5 kcal/mol with a low transition barrier (around 9 kcal/mol). Therefore, these conformers are expected to coexist at the room temperature. Several molecular characteristics of quinoline-5-carboxaldehyde obtained through B3LYP and time-dependent B3LYP calculations, such as conformational stability, key geometry parameters, vibrational frequencies, IR and Raman intensities, UV-Vis vertical excitation energies and the corresponding oscillator strengths have been analyzed. The 1H and 13C NMR chemical shifts of quinoline-5-carboxaldehyde were also investigated.

  5. Theoretical studies of the electronic structure of small metal clusters

    Science.gov (United States)

    Jordan, K. D.

    1982-01-01

    Theoretical studies of the electronic structure of metal clusters, in particular clusters of Group IIA and IIB atoms were conducted. Early in the project it became clear that electron correlation involving d orbitals plays a more important role in the binding of these clusters than had been previously anticipated. This necessitated that computer codes for calculating two electron integrals and for constructing the resulting CI Hamiltonions be replaced with newer, more efficient procedures. Program modification, interfacing and testing were performed. Results of both plans are reported.

  6. Mesoscopic structure prediction of nanoparticle assembly and coassembly: Theoretical foundation

    KAUST Repository

    Hur, Kahyun

    2010-01-01

    In this work, we present a theoretical framework that unifies polymer field theory and density functional theory in order to efficiently predict ordered nanostructure formation of systems having considerable complexity in terms of molecular structures and interactions. We validate our approach by comparing its predictions with previous simulation results for model systems. We illustrate the flexibility of our approach by applying it to hybrid systems composed of block copolymers and ligand coated nanoparticles. We expect that our approach will enable the treatment of multicomponent self-assembly with a level of molecular complexity that approaches experimental systems. © 2010 American Institute of Physics.

  7. FTIR, Raman, and UV-Vis spectroscopic and DFT investigations of the structure of iron-lead-tellurate glasses.

    Science.gov (United States)

    Rada, Simona; Dehelean, Adriana; Culea, Eugen

    2011-08-01

    In this work, the effects of iron ion intercalations on lead-tellurate glasses were investigated via FTIR, Raman and UV-Vis spectroscopies. This homogeneous glass system has compositions xFe(2)O(3)·(100-x)[4TeO(2)·PbO(2)], where x = 0-60 mol%. The presented observations in these mechanisms show that the lead ions have a pronounced affinity towards [TeO(3)] structural units, resulting in the deformation of the Te-O-Te linkages, and leading to the intercalation of [PbO( n )] (n = 3, 4) and [FeO( n )] (n = 4, 6) entities in the [TeO(4)] chain network. The formation of negatively charged [FeO(4)](1-) structural units implies the attraction of Pb(2+) ions in order to compensate for this electrical charge. Upon increasing the Fe(2)O(3) content to 60 mol%, the network can accommodate an excess of oxygen through the formation of [FeO(6)] structural units and the conversion of [TeO(4)] into [TeO(3)] structural units. For even higher Fe(2)O(3) contents, Raman spectra indicate a greater degree of depolymerization of the vitreous network than FTIR spectra do. The bands due to the Pb-O bond vibrations are very strongly polarized and the [TeO(4)] structural units convert into [TeO(3)] units via an intermediate coordination stage termed "[TeO(3+1)]" structural units. Our UV-Vis spectroscopic data show two mechanisms: (i) the conversion of the Fe(3+) to Fe(2+) at the same time as the oxidation of Pb(2+) to Pb(+4) ions for samples with low Fe(2)O(3) contents; (ii) when the Fe(2)O(3) content is high (x ≥ 50 mol%), the Fe(2+) ions capture positive holes and are transferred to Fe(3+) ions through a photochemical reaction, while the Pb(2+) ions are formed by the reduction of Pb(4+) ions. DFT calculations show that the addition of Fe(2)O(3) to lead-tellurate glasses seems to break the axial Te-O bonds, and the [TeO(4)] structural units are gradually transformed into [TeO(3+1)]- and [TeO(3)]-type polyhedra. Analyzing these data further indicates a gradual

  8. Study on structure, vibrational analysis and molecular characteristics of some halogen substituted azido-phenylethanones using FTIR spectra and DFT

    Science.gov (United States)

    Prashanth, J.; Reddy, Byru Venkatram

    2018-03-01

    The Fourier transform infrared (FTIR) spectra of organic compounds 4-fluoro-2-azido-1-phenylethanone (FAP), 4-chloro-2-azido-1-phenylethanone (CAP) and 4-bromo-2-azido-1-phenylethanone (BAP) have been recorded in the region 4000-400 cm-1. The optimized molecular structure for global minimum energy of the titled molecules is determined by evaluating torsional potentials as a function of rotation angle about free rotation bonds among the substituent groups subjecting them to DFT employing B3LYP functional with 6-311++G (d,p) basis set. The vibrational frequencies along with infrared intensities are computed by SQM procedure. The rms error between observed and calculated frequencies is found to be 9.27, 8.17 and 7.95 cm-1 for FAP, CAP and BAP, respectively which shows good agreement between experimental and scaled values of calculated frequencies obtained by DFT. The vibrational assignments of all the fundamental bands of each molecule are made unambiguously using PED and eigen vectors obtained in the computations. The computed values of dipole moment, polarizability and hyperpolarizability indicate that the titled molecules exhibit NLO behaviour and hence may be considered for potential applicants for the development of NLO materials. HOMO and LUMO energies evaluated in the study demonstrate chemical stability of the molecules. NBO analysis is made to study the stability of the molecules arising from hyper conjugative interactions and charge delocalization. The molecular electrostatic surface potential (MESP) and thermodynamic parameters are also evaluated.

  9. Atomic and electronic structure of surfaces theoretical foundations

    CERN Document Server

    Lannoo, Michel

    1991-01-01

    Surfaces and interfaces play an increasingly important role in today's solid state devices. In this book the reader is introduced, in a didactic manner, to the essential theoretical aspects of the atomic and electronic structure of surfaces and interfaces. The book does not pretend to give a complete overview of contemporary problems and methods. Instead, the authors strive to provide simple but qualitatively useful arguments that apply to a wide variety of cases. The emphasis of the book is on semiconductor surfaces and interfaces but it also includes a thorough treatment of transition metals, a general discussion of phonon dispersion curves, and examples of large computational calculations. The exercises accompanying every chapter will be of great benefit to the student.

  10. Experimental and theoretical studies on the structural, spectroscopic and hydrogen bonding on 4-nitro-n-(2,4-dinitrophenyl) benzenamine

    Science.gov (United States)

    Subhapriya, G.; Kalyanaraman, S.; Jeyachandran, M.; Ragavendran, V.; Krishnakumar, V.

    2018-04-01

    Synthesized 4-nitro-N-(2,4-dinitrophenyl) benzenamine (NDPBA) molecule was confirmed applying the tool of NMR. Theoretical prediction addressed the NMR chemical shifts and correlated well with the experimental data. The molecule subjected to theoretical DFT at 6-311++G** level unraveled the spectroscopic and structural properties of the NDPBA molecule. Moreover the structural features proved the occurrence of intramolecular Nsbnd H· · O hydrogen bonding in the molecule which was further confirmed with the help of Frontier molecular orbital analysis. Vibrational spectroscopic characterization through FT-IR and Raman experimentally and theoretically gave an account for the vibrational properties. An illustration of the topology of the molecule theoretically helped also in finding the hydrogen bonding energy.

  11. Experimental and theoretical studies of the structure of tellurate-borate glasses network.

    Science.gov (United States)

    Rada, Simona; Culea, Eugen; Neumann, Manfred

    2010-08-01

    The structural properties of the xTeO(2) x (1-x)B(2)O(3) glasses (x = 0.6; 0.7) were investigated by FT-IR spectroscopy. From the analysis of the FTIR spectra, it is reasonable to assume that by the increasing of boron ions content, the tetrahedral [BO(4)] units are gradually replaced by the trigonal [BO(3)] units. The increase in the number of non-bridging oxygen atoms would decrease the connectivity of the glass network and will yield the depolymerization of the borate chains. The molecular structure and vibrational frequencies of the proposed structural models have been studied by exploring the density functional theory (DFT) calculations. The FTIR spectra of the xTeO(2) x (1-x)B(2)O(3) vitreous systems were compared with the calculated spectrum. This procedure allowed us to assign most of the observed IR bands.

  12. New derivatives of (E,E)-azomethines: Design, quantum chemical modeling, spectroscopic (FT-IR, UV/Vis, polarization) studies, synthesis and their applications: Experimental and theoretical investigations

    Science.gov (United States)

    Sheikhi, Masoome; Shahab, Siyamak; Filippovich, Liudmila; Yahyaei, Hooriye; Dikusar, Evgenij; Khaleghian, Mehrnoosh

    2018-01-01

    In present work, Polarization, Excited States, FT-IR, 1H, 13C NMR, Trans-Cis (E → Z) Isomerization Properties and Anisotropy of Thermal and Electrical Conductivity of the three new Azomethines dyes such as: 4-((E)-((4-((E)-phenyldiazenyl)phenyl)imino)methyl)benzoic acid (I), 5-phenyl-N-(pyrimidin-2-yl)isoxazole-3-carboxamide (II) and (Z)-1-(4-((E)-((4-phenylcyclopenta-1,4-dien-1-yl)methylene)amino)phenyl)ethanone oxime (III) in the presence of polyvinyl alcohol (PVA) matrix were studied. The absorption spectrum of the I, II and III in dimethylformamide (DMF) solution was calculated. The nature of absorption peaks of the dyes in the UV/Vis spectral regions was interpreted. The molecular HOMO-LUMO, excitation energies and oscillator strengths for E and Z isomers of the I, II and III have also been calculated and presented. Optical Properties of the PVA-films containing these new synthesized dyes have investigated. Polarizing Efficiency (PE) of obtained PVA-film is 97-98% at Stretching Degree (Rs) 3.5. Anisotropy of thermal and electrical conductivity of the PVA-films containing the title compounds was also measured and discussed.

  13. A theoretical and spectroscopic study of conformational structures of piroxicam

    Science.gov (United States)

    Souza, Kely Ferreira de; Martins, José A.; Pessine, Francisco B. T.; Custodio, Rogério

    2010-02-01

    Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

  14. Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV and NBO analysis of 2-chlorobenzonitrile by density functional method.

    Science.gov (United States)

    Krishnan, Akhil R; Saleem, H; Subashchandrabose, S; Sundaraganesan, N; Sebastain, S

    2011-02-01

    In this work, we will report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV spectral analysis of 2-chlorobenzonitrile (2-ClBN). The FT-IR solid phase (4000-400 cm(-1)), and FT-Raman spectra (3500-50 cm(-1)) of 2-ClBN was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 2-ClBN in the ground state have been calculated by using the density functional methods (BLYP, B3LYP) with 6-31G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* anti bonding orbitals and E2 energies confirms the occurrence of ICT (Intra molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethanol solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. Finally calculated results were applied to simulated Infrared and Raman spectra of the title compound which show good agreement with observed spectra. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Crystal and molecular structure studies of (Z)-N-methyl-C-4-substituted phenyl nitrones by XRD, DFT, FTIR and NMR methods

    Science.gov (United States)

    Lasri, Jamal; Eltayeb, Naser Eltaher; Haukka, Matti; Alghamdi, Yousef

    2017-01-01

    (Z)-N-methyl-C-4-substituted phenyl nitrones -O+N(Me)=C(H)R (Z-2a R = 4-ClC6H4, Z-2b R = 4-NO2C6H4, Z-2c R = 4-CH3OC6H4) were synthesized and characterized by elemental analyses, FTIR, 1H, 13C and DEPT-135 NMR spectroscopy and also by single crystal X-ray diffraction (in the case of Z-2a and Z-2b). The geometries of the nitrone molecules Z-2a, Z-2b and Z-2c and their E-isomers; (E)-N-methyl-C-4-chlorophenyl nitrone E-2a, (E)-N-methyl-C-4-nitrophenyl nitrone E-2b and (E)-N-methyl-C-4-methoxyphenyl nitrone E-2c were optimized using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level of theory. The theoretical vibrational frequencies obtained by DFT calculations are in good agreement with the experimental values. The electronics structures were described in terms of the distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Gauge independent atomic orbital (GIAO) method was used to calculate the NMR spectra, the correlation between the calculated and experimental chemical shifts is mostly in the range of 0.94-0.97 for 1H, whereas, the correlation for 13C is 0.99. Thermodynamics study showed that the Z-isomer is favoured than E-isomer with energy barrier of 7.1, 7.2 and 7.1 kcal/mol for Z-2a, Z-2b and Z-2c, respectively. The abundance of the most stable species Z-isomers is equal to 99.99% for all three compounds at 298 K in gas phase.

  16. Fourier Transform Infrared (FTIR) Spectroscopy, Ultraviolet Resonance Raman (UVRR) Spectroscopy, and Atomic Force Microscopy (AFM) for Study of the Kinetics of Formation and Structural Characterization of Tau Fibrils.

    Science.gov (United States)

    Ramachandran, Gayathri

    2017-01-01

    Kinetic studies of tau fibril formation in vitro most commonly employ spectroscopic probes such as thioflavinT fluorescence and laser light scattering or negative stain transmission electron microscopy. Here, I describe the use of Fourier transform infrared (FTIR) spectroscopy, ultraviolet resonance Raman (UVRR) spectroscopy, and atomic force microscopy (AFM) as complementary probes for studies of tau aggregation. The sensitivity of vibrational spectroscopic techniques (FTIR and UVRR) to secondary structure content allows for measurement of conformational changes that occur when the intrinsically disordered protein tau transforms into cross-β-core containing fibrils. AFM imaging serves as a gentle probe of structures populated over the time course of tau fibrillization. Together, these assays help further elucidate the structural and mechanistic complexity inherent in tau fibril formation.

  17. Structural Changes in Cooked Rice Treated with Cooling-Reheating Process and Coconut Milk Addition as Observed With FT-IR and 13C NMR

    Directory of Open Access Journals (Sweden)

    Nuri Arum Anugrahati

    2017-03-01

    Full Text Available The molecular structural changes of food could be observed by the technique of FT-IR and 13C NMR spectroscopy. This research was aimed to study the structural changes in cooked rice treated with cooling-reheating process and coconut milk addition using FT-IR and 13C NMR. It was found that the cooling-reheating process and addition of coconut milk cause several structural changes of cooked rice. The IR analysis showed the bands at 3,400, 2,900, 1,018 and 856 cm-1 changed due to the retrogradation during cooling process. The spectrum of 13C NMR showed the change of peaks at 100.28 and 100.10 ppm. These changes may be related to the addition of coconut milk during rice cooking.

  18. Study on molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM, HOMO-LUMO energies and docking studies of 5-fluorouracil, a substance used to treat cancer

    Science.gov (United States)

    Almeida, Michell O.; Barros, Daiane A. S.; Araujo, Sheila C.; Faria, Sergio H. D. M.; Maltarollo, Vinicius G.; Honorio, Kathia M.

    2017-09-01

    Cancer cells can expand to other parts of body through blood system and nodes from a mechanism known as metastasis. Due to the large annual growth of cancer cases, various biological targets have been studied and related to this disorder. A very interesting target related to cancer is human epidermal growth factor receptor 2 (HER2). In this study, we analyzed the main intermolecular interactions between a drug used in the cancer treatment (5-fluorouracil) and HER2. Molecular modeling methods were also employed to assess the molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM and HOMO-LUMO energies of 5-FU. From the docking simulations it was possible to analyze the interactions that occur between some residues in the binding site of HER2 and 5-FU. To validate the choice of basis set that was used in the NBO and QTAIM analyses, theoretical calculations were performed to obtain FT-IR and UV/Vis spectra, and the theoretical results are consistent with the experimental data, showing that the basis set chosen is suitable. For the maximum λ from the theoretical calculation (254.89 nm) of UV/Vis, the electronic transition from HOMO to LUMO occurs at 4.89 eV. From NBO analyses, we observed interactions between Asp863 and 5-FU, i.e. the orbitals with high transfer of electrons are LP O15 (donor NBO) and BD* (π) N1-H10 (acceptor NBO), being that the value of this interaction is 7.72 kcal/mol. Results from QTAIM indicate one main intermolecular H bond, which is necessary to stabilize the complex formed between the ligands and the biological target. Therefore, this study allowed a careful evaluation on the main structural, spectroscopic and electronic properties involved in the interaction between 5-FU and HER2, an important biological complex related to the cancer treatment.

  19. Proteolytically-induced changes of secondary structural protein conformation of bovine serum albumin monitored by Fourier transform infrared (FT-IR) and UV-circular dichroism spectroscopy.

    Science.gov (United States)

    Güler, Günnur; Vorob'ev, Mikhail M; Vogel, Vitali; Mäntele, Werner

    2016-05-15

    Enzymatically-induced degradation of bovine serum albumin (BSA) by serine proteases (trypsin and α-chymotrypsin) in various concentrations was monitored by means of Fourier transform infrared (FT-IR) and ultraviolet circular dichroism (UV-CD) spectroscopy. In this study, the applicability of both spectroscopies to monitor the proteolysis process in real time has been proven, by tracking the spectral changes together with secondary structure analysis of BSA as proteolysis proceeds. On the basis of the FTIR spectra and the changes in the amide I band region, we suggest the progression of proteolysis process via conversion of α-helices (1654 cm(-1)) into unordered structures and an increase in the concentration of free carboxylates (absorption of 1593 and 1402 cm(-1)). For the first time, the correlation between the degree of hydrolysis and the concentration of carboxylic groups measured by FTIR spectroscopy was revealed as well. The far UV-CD spectra together with their secondary structure analysis suggest that the α-helical content decreases concomitant with an increase in the unordered structure. Both spectroscopic techniques also demonstrate that there are similar but less spectral changes of BSA for the trypsin attack than for α-chymotrypsin although the substrate/enzyme ratio is taken the same. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Regional Economic Policy: Structural Approach and Tools (Theoretical Formulation

    Directory of Open Access Journals (Sweden)

    Oleg Sergeevich Sukharev

    2015-06-01

    Full Text Available The subject matter of the article — the development of the doctrine of “coherent” Regional Development and research of the structural quality of the development of regional systems on the basis of theoretical analysis of institutional factors (parameters that determine the manufacturability of the regional economy. The purpose of the research — to show the possibilities of technological change and shift of economic growth in a particular regional system, with stringent limits for accelerated development, with an emphasis on industrial regions. To this end, formed a number of structural models and analyze the impact of technological factors on the growth parameters of the regional economy, the definition of conditions for the development of the industrial region. Methodology. The correlation and regression analysis are applied, which allows to establish a statistically significant relationship between the relevant parameters, the econometric models are used to demonstrate the possibility of estimating the growth parameters via the control parameters, including the technological factor. The structural aspect of regional economic growth is taken into account by the division of investment on the old and new technologies. Result and scope of the research. Increasing adaptability of the regional economy is possible at the expense of compounding results in the use of (old and the application of new technologies. This principle specifies the algorithm of formation of regional development priorities, provides a choice of strategy of technological development of the regional system. Investing resources only in the field of new technologies can dramatically enhance the disparity of regional economic system, the parameters of diversion of resources and the creation of a new resource will determine the pace of growth in the region. Conclusions. Dynamics of investment into old technology provides a major impact on the rate of economic growth in the

  1. Synthesis, crystal structure, vibrational spectra and theoretical calculations of quantum chemistry of a potential antimicrobial Meldrum's acid derivative

    Science.gov (United States)

    Campelo, M. J. M.; Freire, P. T. C.; Mendes Filho, J.; de Toledo, T. A.; Teixeira, A. M. R.; da Silva, L. E.; Bento, R. R. F.; Faria, J. L. B.; Pizani, P. S.; Gusmão, G. O. M.; Coutinho, H. D. M.; Oliveira, M. T. A.

    2017-10-01

    A new derivative of Meldrum's acid 5-((5-chloropyridin-2-ylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (CYMM) of molecular formula C12H11ClN2O4 was synthesized and structurally characterized using single crystal X-ray diffraction technique. The vibrational properties of the crystal were studied by Fourier Transform infrared (FT-IR), Fourier Transform Raman (FT-Raman) techniques and theoretical calculations of quantum chemistry using Density functional theory (DFT) and Density functional perturbation theory (DFPT). A comparison with experimental spectra allowed the assignment of all the normal modes. The descriptions of the normal modes were carried by means of potential energy distribution (PED). Additionally, analysis of the antimicrobial activity and antibiotic resistance modulatory activity was carried out to evaluate the antibacterial potential of the CYMM.

  2. ATR-FTIR and density functional theory study of the structures, energetics, and vibrational spectra of phosphate adsorbed onto goethite.

    Science.gov (United States)

    Kubicki, James D; Paul, Kristian W; Kabalan, Lara; Zhu, Qing; Mrozik, Michael K; Aryanpour, Masoud; Pierre-Louis, Andro-Marc; Strongin, Daniel R

    2012-10-16

    Periodic plane-wave density functional theory (DFT) and molecular cluster hybrid molecular orbital-DFT (MO-DFT) calculations were performed on models of phosphate surface complexes on the (100), (010), (001), (101), and (210) surfaces of α-FeOOH (goethite). Binding energies of monodentate and bidentate HPO(4)(2-) surface complexes were compared to H(2)PO(4)(-) outer-sphere complexes. Both the average potential energies from DFT molecular dynamics (DFT-MD) simulations and energy minimizations were used to estimate adsorption energies for each configuration. Molecular clusters were extracted from the energy-minimized structures of the periodic systems and subjected to energy reminimization and frequency analysis with MO-DFT. The modeled P-O and P---Fe distances were consistent with EXAFS data for the arsenate oxyanion that is an analog of phosphate, and the interatomic distances predicted by the clusters were similar to those of the periodic models. Calculated vibrational frequencies from these clusters were then correlated with observed infrared bands. Configurations that resulted in favorable adsorption energies were also found to produce theoretical vibrational frequencies that correlated well with experiment. The relative stability of monodentate versus bidentate configurations was a function of the goethite surface under consideration. Overall, our results show that phosphate adsorption onto goethite occurs as a variety of surface complexes depending on the habit of the mineral (i.e., surfaces present) and solution pH. Previous IR spectroscopic studies may have been difficult to interpret because the observed spectra averaged the structural properties of three or more configurations on any given sample with multiple surfaces.

  3. Structural changes of tissue samples exposed to low frequency electromagnetic field: A FT-IR absorbance study

    OpenAIRE

    Crupi, V.; Interdonato, S.; Majolino, D.; Mondello, M. R.; Pergolizzi, S.; Venuti, V.

    2004-01-01

    In the present work, we report on a preliminary Fourier Transform Infrared (FT-IR) Absorbance study performed on different kind of rat tissues, such as kidney and heart, exposed to a “non-ionizing” radiation source at low frequency, in the range typical of micro-waves (300 MHz < v < 300 GHz). The data were collected in a wide wavenumber region, from 400 cm−1 to 4000 cm−1. The comparison of the absorbance spectra in the case of the normal tissues with the irradiated ones has shown significant ...

  4. The synthesis, characterization, crystal structure and theoretical calculations of a new meso-BOBIPY substituted phthalonitrile

    International Nuclear Information System (INIS)

    Sen, Pinar; Yildiz, S. Zeki; Atalay, Yusuf; Dege, Necmi; Demirtas, Günes

    2014-01-01

    A novel 4-(2-meso-BOBIPY-phenoxy)phthalonitrile (6) derivative has been synthesized starting from BF 3 –OEt 2 complex and 4-(2-meso-dipyrromethene-phenoxy)phthalonitrile (5) which was prepared by the oxidation of 4-(2-meso-dipyrromethane-phenoxy)phthalonitrile (4). The final product exhibit noticeable spectroscopic properties which were examined by its absorption and fluorescence emission spectra. The original compounds prepared in the reaction pathway were characterized by the combination of FT-IR, 1 H and 13 C NMR, UV–vis, MS and HRMS spectral data. The final product (6) was obtained as single crystal which crystallized in the triclinic space group P-1 with a=7.9411 (6) Å, b=9.0150 (6) Å, c=14.419 (1) Å, α=74.917 (5)°, β=86.824 (6)°, γ=84.109 (5)° and Z=2. The crystal structure has intermolecular C–H···F–B and C–H···N interactions. These interactions construct bifurcated hydrogen bonds in the crystal structure. In this study, It has been calculated; molecular structure, vibrational frequencies, 1 H and 13 C NMR chemical shifts and HOMO and LUMO energies of the title compound by using B3LYP method with 6–311++G(dp) basis set, and the electronic spectral characterization was investigated for the target product, as well. - Highlights: • A novel 4-(2-meso-BOBIPY-phenoxy)phthalonitrile derivative has been synthesized. • The title product exhibit noticeable spectroscopic properties which were examined by its absorption and fluorescence emission spectra. • The final product (6) was obtained as single crystal which crystallized in the triclinic space group. • Molecular structure, vibrational frequencies, 1 H and 13 C NMR chemical shifts and HOMO and LUMO energies of the title compound were calculated theoretically. • The electronic spectral characterization was investigated, as well. • The title compound is also open to prepare further BODIPY substituted oligomeric molecules via on it

  5. Numerous applications of fiber optic evanescent wave Fourier transform infrared (FEW-FTIR) spectroscopy for subsurface structural analysis

    Science.gov (United States)

    Afanasyeva, Natalia I.; Welser, Leslie; Bruch, Reinhard F.; Kano, Angelique; Makhine, Volodymyr

    1999-10-01

    A new infrared (IR) interferometric method has been developed in conjunction with low-loss, flexible optical fibers, sensors, and probes. This combination of fiber optical sensors and Fourier Transform (FT) spectrometers can be applied to many fields, including (1) noninvasive medical diagnostics of cancer and other different diseases in vivo, (2) minimally invasive bulk diagnostics of tissue, (3) remote monitoring of tissue, chemical processes, and environment, (4) surface analysis of polymers and other materials, (5) characterization of the quality of food, pharmacological products, cosmetics, paper, and other wood-related products, as well as (6) agricultural, forensic, geological, mining, and archeological field measurements. In particular, our nondestructive, fast, compact, portable, remote and highly sensitive diagnostics tools are very promising for subsurface analysis at the molecular level without sample preparation. For example, this technique is ideal for different types of soft porous foams, rough polymers, and rock surfaces. Such surfaces, as well as living tissue, are very difficult to investigate by traditional FTIR methods. We present here FEW-FTIR spectra of polymers, banana and grapefruit peels, and living tissues detected directly at surfaces. In addition, results on the vibrational spectral analysis of normal and pathological skin tissue in the region of 850 - 4000 cm-1 are discussed.

  6. Theoretical nuclear structure and astrophysics. Progress report for 1996

    Energy Technology Data Exchange (ETDEWEB)

    Guidry, M.W.; Nazarewicz, W.; Strayer, M.R.

    1996-12-31

    This research effort is directed toward theoretical support and guidance for the fields of radioactive ion beam physics, gamma ray spectroscopy, computational and nuclear astrophysics, and the interface between these disciplines. The authors report substantial progress in all those areas. One measure of progress is publications and invited material. The research described here has led to more than 43 papers that are published, accepted, or submitted to refereed journals, and to 15 invited presentations at conferences and workshops.

  7. Theoretical nuclear structure and astrophysics. Progress report for 1996

    International Nuclear Information System (INIS)

    Guidry, M.W.; Nazarewicz, W.; Strayer, M.R.

    1996-01-01

    This research effort is directed toward theoretical support and guidance for the fields of radioactive ion beam physics, gamma ray spectroscopy, computational and nuclear astrophysics, and the interface between these disciplines. The authors report substantial progress in all those areas. One measure of progress is publications and invited material. The research described here has led to more than 43 papers that are published, accepted, or submitted to refereed journals, and to 15 invited presentations at conferences and workshops

  8. Structural stability and theoretical strength of Cu crystal under equal ...

    Indian Academy of Sciences (India)

    The results indicate that, under sufficient tension, there exists a stress-free BCC phase which is unstable and slips spontaneously to a stress-free metastable BCT phase by consuming internal energy. The stable region ranges from −15.131 GPa to 2.803 GPa in the theoretical strength or from −5.801% to 4.972% in the strain ...

  9. Molecular structure and vibrational analysis of Trifluoperazine by FT-IR, FT-Raman and UV-Vis spectroscopies combined with DFT calculations.

    Science.gov (United States)

    Rajesh, P; Gunasekaran, S; Gnanasambandan, T; Seshadri, S

    2015-02-25

    The complete vibrational assignment and analysis of the fundamental vibrational modes of Trifluoperazine (TFZ) was carried out using the experimental FT-IR, FT-Raman and UV-Vis data and quantum chemical studies. The observed vibrational data were compared with the wavenumbers derived theoretically for the optimized geometry of the compound from the DFT-B3LYP gradient calculations employing 6-31G (d,p) basis set. Thermodynamic properties like entropy, heat capacity and enthalpy have been calculated for the molecule. The HOMO-LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Important non-linear properties such as first hyperpolarizability of TFZ have been computed using B3LYP quantum chemical calculation. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Ion-pair structure of vaporized ionic liquid studied by matrix-isolation FTIR spectroscopy with DFT calculations: a case of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate.

    Science.gov (United States)

    Akai, Nobuyuki; Kawai, Akio; Shibuya, Kazuhiko

    2010-12-09

    The matrix-isolation infrared spectrum of a thermally evaporated ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][OTf]), was measured by FTIR spectroscopy and analyzed with the aid of DFT calculations. The main chemical species in the observed IR spectrum was mainly identified as the 1:1 cation-anion pair, which corresponds to the second stable ion-pair structure bonded through five hydrogen bonds between three O atoms of the anion side and four H atoms of the cation.

  11. General theoretical description of ARPES of vdW structures

    OpenAIRE

    Amorim, B.

    2017-01-01

    We develop a general theory to model the angle resolved photoemission spectroscopy (ARPES) of commensurate and incommensurate van der Waals (vdW) structures, formed by lattice mismatched and/or misaligned stacked layers of two-dimensional materials. The present theory is based on a tight-binding description of the structure and the concept of generalized umklapp processes, going beyond previous descriptions of ARPES in incommensurate vdW structures, which are based on continuous, low energy m...

  12. Combining Theoretical Perspectives on the Organizational Structure-Performance Relationship

    Directory of Open Access Journals (Sweden)

    Starling David Hunter

    2015-08-01

    Full Text Available Much of the literature linking organization structure to performance falls into two broad research streams. One stream concerns formal structure – the hierarchy of authority or reporting relationships as well as the degree of standardization, formalization, specialization, etc. The impact of formal structure and other elements of organization design on performance is typically contingent on factors such as strategic orientation, task characteristics, and environmental conditions. The other research stream focuses on informal structure – a network of interpersonal and intra-organizational relationships. Properties of informal structure are typically shown to have a more direct (less contingent impact on organizational performance. Despite these pronounced differences in the conceptualization of organization structure, considerable overlap and complementarity exist between the two research streams. In this article, I compare and contrast a pair of exemplars from each stream – the information processing perspective and the social network perspective – with respect to their conceptualizations of organization structure and its relationship to performance. Several recommendations for future research that combines the two approaches are offered.

  13. Spectroscopic (FT-IR, FT-Raman, UV-Vis) analysis, conformational, HOMO-LUMO, NBO and NLO calculations on monomeric and dimeric structures of 4-pyridazinecarboxylic acid by HF and DFT methods

    Science.gov (United States)

    Eşme, A.; Sağdınç, S. G.

    2017-11-01

    In this study, the Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 4-pyridazinecarboxylic acid (4PCA) in solid phase were recorded and analyzed. Quantum chemical calculations of the optimized molecular structure, energies, conformational, UV-Vis, nonlinear optical (NLO) and natural bond orbital (NBO) analysis, molecular surfaces, Mulliken charges, and vibrational studies for 4PCA were performed using the ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods with 6-311++G(d,p) basis set. Obtained results on the geometric structure and vibrational frequencies are compared with observed data. The dimeric structure of 4PCA with DFT/B3LYP/6-311++G(d,p) level caused by the shifts of Osbnd H and Cdbnd O bands in the vibrational spectra of 4PCA were also studied. Moreover, the spectroscopic and theoretical results were compared with the corresponding properties for monomeric and dimeric structures of 4PCA. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies also confirm that charge transfer occurs within the molecule. NBO analysis confirms the presence of intramolecular charge transfer and the hydrogen bonding interaction. The detailed vibrational assignments were performed with the HF and DFT calculations, and the potential energy distribution (PED) was obtained by the Vibrational Energy Distribution Analysis (VEDA4) program.

  14. Theoretical velocity structure of long-period variable star photospheres

    International Nuclear Information System (INIS)

    Hill, S.J.; Willson, L.A.

    1979-01-01

    Numerical models for shock waves propagating through atmospheres of cool supergiant stars for a grid of masses and surface gravities have been calculated calculated, assuming spherical symmetry, isothermality, and a periodic piston boundary condition. The results of these models can be restated using parameters derived in Willson and Hill; the reparametrization allows the generalization of these results to arbitrary stellar masses and radii. Applying the theoretical generalization to a variety of observed properties of R Leonis and o Ceti allows the selection of a limited range of probable masses and radii for these stars: Mapprox. =0.8--l.5M/sub sun/,Rapprox. =l.3--2.0 x 10 13 cm for o Cet and M=l.8--4.0M/sub sun/, R=l.7--2.5 x 10 13 cm for R Leo. We conclude that both stars are pulsating in the fundamental mode, with a pulsation constant Qapprox. =Od1

  15. C-Ni-Pd and CNT-Ni-Pd film's molecular and crystalline structure investigations by FTIR spectroscopy and XRD diffraction

    Science.gov (United States)

    Stepińska, Izabela; Czerwosz, ElŻbieta; Diduszko, Ryszard; Kozłowski, Mirosław; Wronka, Halina

    2017-08-01

    In this work molecular and crystalline structure of new type of nanocomposite films were investigated. These films compose of CNT decorated with palladium nanograins. They were prepared on a base of C-Ni films modified in CVD process. C-Ni nanocomposite films were obtained by PVD process and their modification by CVD leads to a growth of CNT film. CNTs-Ni or C-Ni films were treated with additional PVD process with palladium. Nickel and palladium acetate and fulleren C60 are precursors of films in PVD process. FTIR spectroscopy was used to studied the molecular structure of film in every stage of preparation . The crystalline structure of these films was studied by X-ray diffraction. SEM (scanning electron microscopy) was applied to investigate film's surface topography.

  16. Ultrasound-mediated structural changes in cells revealed by FTIR spectroscopy: A contribution to the optimization of gene and drug delivery

    Science.gov (United States)

    Grimaldi, Paola; Di Giambattista, Lucia; Giordani, Serena; Udroiu, Ion; Pozzi, Deleana; Gaudenzi, Silvia; Bedini, Angelico; Giliberti, Claudia; Palomba, Raffaele; Congiu Castellano, Agostina

    2011-12-01

    Ultrasound effects on biological samples are gaining a growing interest concerning in particular, the intracellular delivery of drugs and genes in a safe and in a efficient way. Future progress in this field will require a better understanding of how ultrasound and acoustic cavitation affect the biological system properties. The morphological changes of cells due to ultrasound (US) exposure have been extensively studied, while little attention has been given to the cells structural changes. We have exposed two different cell lines to 1 MHz frequency ultrasound currently used in therapy, Jurkat T-lymphocytes and NIH-3T3 fibroblasts, both employed as models respectively in the apoptosis and in the gene therapy studies. The Fourier Transform Infrared (FTIR) Spectroscopy was used as probe to reveal the structural changes in particular molecular groups belonging to the main biological systems. The genotoxic damage of cells exposed to ultrasound was ascertained by the Cytokinesis-Block Micronucleus (CBMN) assay. The FTIR spectroscopy results, combined with multivariate statistical analysis, regarding all cellular components (lipids, proteins, nucleic acids) of the two cell lines, show that Jurkat cells are more sensitive to therapeutic ultrasound in the lipid and protein regions, whereas the NIH-3T3 cells are more sensitive in the nucleic acids region; a meaningful genotoxic effect is present in both cell lines only for long sonication times while in the Jurkat cells also a significant cytotoxic effect is revealed for long times of exposure to ultrasound.

  17. Enzyme distribution and secondary structure of sol-gel immobilized glucose oxidase by micro-attenuated total reflection FT-IR spectroscopy.

    Science.gov (United States)

    Delfino, I; Portaccio, M; Della Ventura, B; Mita, D G; Lepore, M

    2013-01-01

    Glucose oxidase (GOD) immobilized into sol-gel matrices was studied by using Micro-Attenuated Total Reflection Fourier Transform Infrared (micro-ATR FT-IR) spectroscopy in order to characterize enzyme distribution and secondary structure in systems with valuable potentialities in amperometric and optical biosensing. Spectra were acquired in the 4000-600 cm(-1) frequency region and the analysis of specific fingerprints in the FT-IR spectra evidenced that the enzyme was actually immobilized in the matrix. The enzyme spatial distribution was obtained by examining the amide I and amide II band region of spectra from defined sample positions. The deconvolution of the amide I band in terms of lorentzian functions provided information on the secondary structure of the immobilized GOD. By this approach a macroscopic preservation of GOD activity upon immobilization was evidenced along with the existence of some matrix sites with locally inactivated GOD. To our knowledge this is the first example of point-by-point characterization of conformational changes of immobilized enzyme by means of micro-ATR infrared spectroscopy, thus confirming that this technique can be usefully employed for a non- or minimally-invasive detailed micro-characterization of catalytic supports in order to improve their functionality. Copyright © 2012. Published by Elsevier B.V.

  18. Molecular structure, spectroscopic (FT-IR, FT-Raman, NMR, UV) studies and first-order molecular hyperpolarizabilities of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine by density functional method

    Science.gov (United States)

    Subramanian, N.; Sundaraganesan, N.; Jayabharathi, J.

    2010-07-01

    Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine [vanillin azine (VA)] were carried out by using density functional (DFT/B3LYP) method with 6-31G(d) as basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from solid phase FT-IR and FT-Raman spectra are assigned based on the results of the theoretical calculations. The observed spectra are found to be in good agreement with calculated values. The electric dipole moment ( μ) and the first hyperpolarizability ( β) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the VA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the infrared and Raman spectra of VA was also reported. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The theoretical NMR chemical shifts complement with experimentally measured ones.

  19. Theoretical studies in nuclear reactions and nuclear structure

    International Nuclear Information System (INIS)

    1989-08-01

    During the past year, research in theoretical nuclear physics at the University of Maryland attained a number of exciting and important results. These are described in some detail throughout the report, but some of the highlights are as follows: large N c QCD has been shown to place strong constraints on vacuum effects of hadronic field theories; color dielectric models of hadrons have been understood in terms of lattice QCD; we have completed a relativistic analysis of proton scattering to test virtual pair contributions; we have also re-derived the Mandelzweig-Wallace two-body Dirac equation in covariant form, and applied it to the atomic two-body bound states: hydrogen, muonium and positronium; we have carried out the first calculation of the triton binding energy with a realistic quark-based nucleon-nucleon interaction and have learned that new kinds of nonlocalities in the tensor force may produce unexpected results; and we have shown that the Quadronium Conjecture can lead to spontaneous creation of the atom with low momentum as required by the observations, and are constructing a model to quantify the Quadronium phenomenology of the e + e - Puzzle

  20. Chemical structures and theoretical models of lean premixed ...

    African Journals Online (AJOL)

    To better understand the chemistry involved in the lean-fuel combustion, the chemical structure of lean premixed propene-oxygen-nitrogen flames stabilized on a flat-flame burner at atmospheric pressure was determined experimentally. The species mole fraction profiles were also computed by the Premix code and three ...

  1. Ab-initio theoretical predictions of structure properties of semiconductors

    International Nuclear Information System (INIS)

    Rodriguez, C.O.; Peltzer y Blanca, E.L.; Cappannini, O.M.

    1983-01-01

    In this paper, calculations of the total energies and related structural properties of Si, GaP and C are presented showing good agreement with experimental values. The total energy is calculated within the local-density functional formalism using first principles non-local pseudopotentials. (A.C.A.S.) [pt

  2. Theoretical approaches to clustering and fine structure in heaviest elements

    International Nuclear Information System (INIS)

    Silisteanu, I.; Sandru, A.; Silisteanu, A. O.; Popovici, B.; Neacsu, A.

    2007-01-01

    Alpha clustering and fine structure provide unique information on the nuclear scale structure of the heaviest elements. Recent developments in superheavy element research allow us to formulate a quantitative theory of radioactive decay, within multichannel resonance scattering approach, which is described in this work. The work emphasizes the theory extended to more complex nuclear structure at the limits of stability and treats the emission rates near the resonance threshold. The material covered includes formal considerations of the decay problem, derived from a microscopic formulation, as well as practical computational methods, based on self consistent models for nuclear structure and low-energy reaction dynamics. The reliability of the results is demonstrated by a comparison between the decay data with relevant theories and with other approaches. Particular emphasis is given to the resonance spectroscopy with position-sensitive charge particle detectors since high precision calculation of partial widths of narrow resonances have become available and these resonances can be observed in experiments. A primary goal of this work is to study the α-decay properties of new superheavy nuclides with Z 106-118, under current experimental research.(authors)

  3. Theoretical study on the structural effect of some organic ...

    African Journals Online (AJOL)

    A quantitative structure property relationship (QSPR) analysis of some organic compounds (imines or Schiff bases) is studied. The corrosion inhibition efficiencies of these imines have been studied by using AM1 (Austin model 1) Hamiltonian SCF-MO method and QSPR analysis. One of the most promising semiempirical ...

  4. A theoretical study on the B3 phases of ZnSe: Structural and ...

    Indian Academy of Sciences (India)

    KHOIROM Kabita

    2017-06-20

    Jun 20, 2017 ... fabrication of blue light emitting diodes, quantum well devices, infrared window lenses etc. It crystallizes in four-fold coordinated zinc-blende (ZB) structure that is in B3 phase under ambient pressure. ZnSe is intensively studied, experimentally as well as theoretically, using different methods. Theoretical ...

  5. Automated Structural Optimization System (ASTROS). Volume 1. Theoretical Manual

    Science.gov (United States)

    1988-12-01

    Analysis Problem Oriented Language). Such a control language, similar to the DMAP of NASTRAN or the typical query language of a data base management...aerospace environment is addressed by making the ASTROS procedure resemble that of NASTRAN in terms of user input and pre- and post-processor interfaces...While the ASTROS procedure does not contain many of the specialized capabilities available in NASTRAN , the basic structural analysis features have

  6. Visualization of atomic structure using AFM: theoretical description

    OpenAIRE

    Gallyamov, M. O.; Yaminsky, I. V.

    2011-01-01

    We suggest simple model of image formation in atomic force microscope (AFM) taking into account contact deformations of probe and sample during scanning. The model explains the possibility of AFM visualization of regular atomic or molecular structure when probe-sample contact area is greater than an area per atom or molecule in surface lattice. (This is usually the case when lattice to be studied has subnanometer unit cell parameters and AFM investigations are carried out in air in contact mo...

  7. Theoretical study on the molecular and crystal structures of nitrogen ...

    Indian Academy of Sciences (India)

    The molecular and crystal structure of the adduct NF3·BF3 was studied computationally using density functional theory. It shows that the adduct exists in the form of a complex but is not ionic. The heats of formation in the gas and the condensed phase of the adduct are −1266.09 and −1276.37 kJ·mol−1, respectively, which ...

  8. Coupled and extended quintessence: Theoretical differences and structure formation

    International Nuclear Information System (INIS)

    Pettorino, Valeria; Baccigalupi, Carlo

    2008-01-01

    The case of a coupling between dark energy and matter [coupled quintessence (CQ)] or gravity [extended quintessence (EQ)] has recently attracted a deep interest and has been widely investigated both in the Einstein and in the Jordan frames (EF, JF), within scalar-tensor theories. Focusing on the simplest models proposed so far, in this paper we study the relation existing between the two scenarios, isolating the Weyl scaling which allows one to express them in the EF and JF. Moreover, we perform a comparative study of the behavior of linear perturbations in both scenarios, which turn out to behave in a markedly different way. In particular, while the clustering is enhanced in the considered CQ models with respect to the corresponding quintessence ones where the coupling is absent and to the ordinary cosmologies with a cosmological constant and cold dark matter (ΛCDM), structures in EQ models may grow slower. This is likely to have direct consequences on the inner properties of nonlinear structures, like cluster concentration, as well as on the weak lensing shear on large scales. Finally, we specialize our study for interfacing linear dynamics and N-body simulations in these cosmologies, giving a recipe for the corrections to be included in N-body codes in order to take into account the modifications to the expansion rate, growth of structures, and strength of gravity

  9. Theoretical studies in nuclear reactions and nuclear structure

    International Nuclear Information System (INIS)

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon's mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon's mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon's mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e + e - problem and heavy ion dynamics

  10. Theoretical aspects of electronic structure of high Tc superconductors

    International Nuclear Information System (INIS)

    Gupta, R.P.

    1990-01-01

    Although the mechanism responsible for the high T c superconductivity is still unknown, it is nevertheless clear that superconductivity in hole doped materials depends sensitively on the number of holes, C h , per CuO 2 plane. A correlation between C h and T c has been established. In this paper we present several examples of the critical dependence of the charge transfer and thus the value of C h on the cristallographic characteristics. For example, our electronic structure investigations of YBa 2 Cu 3 O 6.5 using several configurations of the oxygen atoms on the chains show that the order-disorder phenomena of the oxygen atoms play a crucial role on the value of C h and T c . We have also studied the variation of the charge transfer and C h as a function of hydrostatic pressure for several cuprates: La 1.85 Sr 0.15 CuO 4 (ΔT c /Δp ∼ 0.3 - 0.4 K/kbar); YBa 2 Cu 4 O 8 (ΔT c /Δp ∼ 5.5 K/kbar). We show that the values of C h increase under pressure [fr

  11. Synchrotron FTIR micro-spectroscopy for structural analysis of Lewy bodies in the brain of Parkinson’s disease patients

    Science.gov (United States)

    Araki, Katsuya; Yagi, Naoto; Ikemoto, Yuka; Yagi, Hisashi; Choong, Chi-Jing; Hayakawa, Hideki; Beck, Goichi; Sumi, Hisae; Fujimura, Harutoshi; Moriwaki, Taro; Nagai, Yoshitaka; Goto, Yuji; Mochizuki, Hideki

    2015-12-01

    Lewy bodies (LBs), which mainly consist of α-synuclein (α-syn), are neuropathological hallmarks of patients with Parkinson’s disease (PD). The fine structure of LBs is unknown, and LBs cannot be made artificially. Nevertheless, many studies have described fibrillisation using recombinant α-syn purified from E. coli. An extremely fundamental problem is whether the structure of LBs is the same as that of recombinant amyloid fibrils. Thus, we used synchrotron Fourier transform infrared micro-spectroscopy (FTIRM) to analyse the fine structure of LBs in the brain of PD patients. Our results showed a shift in the infrared spectrum that indicates abundance of a β-sheet-rich structure in LBs. Also, 2D infrared mapping of LBs revealed that the content of the β-sheet structure is higher in the halo than in the core, and the core contains a large amount of proteins and lipids.

  12. Effect of alkali metal ions on the pyrrole and pyridine π-electron systems in pyrrole-2-carboxylate and pyridine-2-carboxylate molecules: FT-IR, FT-Raman, NMR and theoretical studies

    Science.gov (United States)

    Świderski, G.; Wojtulewski, S.; Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

    2011-05-01

    The FT-IR, FT-Raman and 1H and 13C NMR spectra of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium, rubidium and caesium pyrrole-2-carboxylates were recorded, assigned and compared in the Li → Na → K → Rb → Cs salt series. The effect of alkali metal ions on the electronic system of ligands was discussed. The obtained results were compared with previously reported ones for pyridine-2-carboxylic acid and alkali metal pyridine-2-carboxylates. Calculations for pyrrole-2-carboxylic acid and Li, Na, K pyrrole-2-carboxylates in B3LYP/6-311++G ** level and Møller-Plesset method in MP2/6-311++G ** level were made. Bond lengths, angles and dipole moments as well as aromaticity indices (HOMA, EN, GEO, I 6) for the optimized structures of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium pyrrole-2-carboxylates were also calculated. The degree of perturbation of the aromatic system of ligand under the influence of metals in the Li → Cs series was investigated with the use of statistical methods (linear correlation), calculated aromaticity indices and Mulliken, NBO and ChelpG population analysis method. Additionally, the Bader theory (AIM) was applied to setting the characteristic of the bond critical points what confirmed the influence of alkali metals on the pyrrole ring.

  13. Theoretical studies of structure and dynamics of chalcogenide glasses

    Science.gov (United States)

    Inam, Fakharul

    In this work, the structural and dynamical properties of Ge-Se and Ag-Ge-Se glasses, using first principle molecular dynamics simulations, is presented. Raman and calorimetric studies on GeXSe1- x glasses have provided evidence for the existence of the intermediate phase (IP) in chalcogenides and other glasses. Here we thoroughly discuss the ab-initio models of Ge XSe1-x glasses over a wide composition range and provide an atomistic picture of the IP. A thorough analysis of our models reveals that the IP in these glasses may arise from the competition between amorphous GeSe2 and a polymeric a-Se phases, which gives rise to the non-monotonic evolution (a topological feature of the IP) of the network parameters through the IP window. A qualitative comparison is made between the topological features extracted from the models and the experiments. A possible electronic signature of the IP in terms of the shift in the conduction edge energy in the IP range is predicted. The results agree with the shift in the white line position for the Se atoms in the K-edge X-Ray Absorption Near Edge Structure (XANES) spectra. A microscopic picture of the silver dynamics in GeSe3 :Ag glass is presented. The dynamics of Ag is explored at two temperatures: 300K and 700K. In the relaxed GeSe3 glass network, it is shown that the Ag occupies trapping centers (TC) that exist between pairs of suitably separated host sites. The charge state of the Ag in the glass network is computed and it is shown that Ag is neutral if weakly bonded and is Ag+ if in a trapping center. The dynamics of the Ag is shown to be largely effected by the neighboring host sties. At room temperature, Ag is mainly trapped at the TC with small hopping probability between neighboring TCs. At higher temperature (700 K), the Ag motion is diffusive and is proceeded via a trapping-release dynamics between supertraps or cages consisting of multiple trapping center sites in a small volume. Our work offers a first

  14. Pressure effects on the structure, kinetic, and thermodynamic properties of heat-induced aggregation of protein studied by FT-IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Y [Applied Chemistry Department, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan); Okuno, A [Research Department 3, Central Research, Bridgestone Co. Kodaira, Tokyo 187-8531 (Japan); Kato, M, E-mail: taniguti@sk.ritsumei.ac.j [Pharmaceutical Sciences Department, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan)

    2010-03-01

    Pressure can retrain the heat-induced aggregation and dissociate the heat-induced aggregates. We observed the aggregation-preventing pressure effect and the aggregates-dissociating pressure effect to characterize the heat-induced aggregation of equine serum albumin (ESA) by FT-IR spectroscopy. The results suggest the {alpha}-helical structure collapses at the beginning of heat-induced aggregation through the swollen structure, and then the rearrangement of structure to the intermolecular {beta}-sheet takes place through partially unfolded structure. We determined the activation volume for the heat-induced aggregation ({Delta}V'' = +93 ml/mol) and the partial molar volume difference between native state and heat-induced aggregates ({Delta}V=+32 ml/mol). This positive partial molar volume difference suggests that the heat-induced aggregates have larger internal voids than the native structure. Moreover, the positive volume change implies that the formation of the intermolecular {beta}-sheet is unfavorable under high pressure.

  15. Effect of structural relaxation of glassy PET on crystallization process observed by the simultaneous DSC-XRD and DSC-FTIR

    International Nuclear Information System (INIS)

    Yoshii, Tomoko; Yoshida, Hirohisa; Kawai, Tadashi

    2005-01-01

    The effect of structural relaxation of the glassy poly(ethylene terephtalate) (PET) caused by annealing below its glass transition temperature (T g ) on the cold-crystallization observed was investigated by the simultaneous DSC-FTIR and DSC-XRD methods. The nucleation and the conformational ordering processes proceeded faster by annealing. From the relationship between the absorbance change and the exothermic heat during the cold-crystallization, the heat of cold-crystallization for the unannealed PET was caused mainly by the conformational ordering. For the annealed PET, the long range ordering contributed to the heat of crystallization in the late stage of cold-crystallization, which was also confirmed by the DSC-XRD method

  16. New organic single crystal of (benzylthio)acetic acid: Synthesis, crystal structure, spectroscopic (ATR-FTIR, 1H and 13C NMR) and thermal characterization

    Science.gov (United States)

    Sienkiewicz-Gromiuk, Justyna; Tarasiuk, Bogdan; Mazur, Liliana

    2016-04-01

    (Benzylthio)acetic acid (Hbta) was synthesized with 78% yield from benzyl chloride and thiourea as substrates. Well-shaped crystals of Hbta were grown by slow solvent evaporation technique from pure methanol. The compound was investigated by single-crystal X-ray and powder diffraction techniques and was also characterized by other analytical methods, like ATR-FTIR, 1H and 13C NMR and TG/DSC. The acid molecule adopts bent conformation in the solid state. The crystal structure of Hbta is stabilized by numerous intermolecular interactions, including O-H···O, C-H···O, C-H···S and C-H···π contacts. Thermal decomposition of the obtained material takes place above 150 °C.

  17. Recent progress in Fourier Transform Infrared (FTIR) spectroscopy study of compositional, structural, and physical attributes of developmental cotton fibers

    Science.gov (United States)

    Cotton fibers are natural plant products and their end-use qualities depend on their stages of development. In general, the quantity of natural fiber cellulose I (ß 1'4 linked glucose residues) increases rapidly, thus it leads to compositional, structural, and physical attribute variations among the...

  18. Electronic structure of copper phthalocyanine : An experimental and theoretical study of occupied and unoccupied levels

    NARCIS (Netherlands)

    Evangelista, Fabrizio; Carravetta, Vincenzo; Stefani, Giovanni; Jansik, Branislav; Alagia, Michele; Stranges, Stefano; Ruocco, Alessandro

    2007-01-01

    An experimental and theoretical study of the electronic structure of copper phthalocyanine (CuPc) molecule is presented. We performed x-ray photoemission spectroscopy (XPS) and photoabsorption [x-ray absorption near-edge structure (XANES)] gas phase experiments and we compared the results with

  19. Theoretical and simulation analysis of the fiber optical parametric amplifier (FOPA) with cascaded structure

    Science.gov (United States)

    Gao, Jie; Cao, Yongsheng; Chen, Fushen; Sun, Bao; Hu, Zhefeng

    2012-02-01

    A novel scheme is proposed to obviously improve the amplified gain, gain flatness and bandwidth characteristics of FOPA by applying a cascaded fiber structure. The basic structure of the cascaded fiber optical parametric amplifier (CFOPA) is introduced. Then, the expression of signals pass gain characteristic is obtained by utilizing a set of coupled equations. The gain, bandwidth and gain flatness characteristics of the CFOPA with the different parameters of DCF, such as fiber length l/, dispersion slope dD//dλ, and so on, are theoretical analyzed and optimized. Furthermore, simulation analysis is applied to verify the theoretical results by using Optisystem 7.0 software. Although, there are a few deviations between the simulation and the theoretical results, the simulation results effectively demonstrate the validity and feasibility of the theoretical analysis.

  20. Molecular chemistry of plant protein structure at a cellular level by synchrotron-based FTIR spectroscopy: Comparison of yellow ( Brassica rapa) and Brown ( Brassica napus) canola seed tissues

    Science.gov (United States)

    Yu, Peiqiang

    2008-05-01

    The objective of this study was to use synchrotron light sourced FTIR microspectroscopy as a novel approach to characterize protein molecular structure of plant tissue: compared yellow and brown Brassica canola seed within cellular dimensions. Differences in the molecular chemistry and the structural-chemical characteristics were identified between two type of plant tissues. The yellow canola seeds contained a relatively lower (P < 0.05) percentage of model-fitted α-helices (33 vs. 37), a higher (P < 0.05) relative percentage of model-fitted β-sheets (27 vs. 21) and a lower (P < 0.05) ratio of α-helices to β-sheets (1.3 vs. 1.9) than the brown seeds. These results may indicate that the protein value of the yellow canola seeds as food or feed was different from that of the brown canola seeds. The cluster analysis and principal component analysis did not show clear differences between the yellow and brown canola seed tissues in terms of protein amide I structures, indicating they are related to each other. Both yellow and brown canola seeds contain the same proteins but in different ratios.

  1. Investigation of composition and structure of spongy and hard bone tissue using FTIR spectroscopy, XRD and SEM

    Science.gov (United States)

    Al-Akhras, M.-Ali H.; Hasan Qaseer, M. K.; Albiss, B. A.; Alebrhim, M. Anwar; Gezawa, Umar S.

    2018-02-01

    Valuable structural and chemical features can be obtained for spongy and hard bone by infrared spectroscopy and X-ray diffraction. A better understanding of chemical and structural differences between spongy and hard bone is a very important contributor to bone quality. Our data according to IR data showed that the collagen cross-links occurred to be higher in spongy bone, and crystallinity was lower in spongy bone. Deconvolution of the infrared band near 870 cm-1 reveals evidence for A2-type carbonate substitution on hydroxyapatite of spongy bone in addition to the A and B type carbonate substitution that are also found in hard bone. IR and XRD data confirmed the results of each other since full width at half maximum of 002-apatite pattern of XRD showed that the crystallinity was lower in spongy bone. The microstructure was examined by using scanning electron microscope and the result showed that the lattice of thin threads in spongy bone and is less dense than hard bone.

  2. A Comparative Study of Theoretical Graph Models for Characterizing Structural Networks of Human Brain

    Directory of Open Access Journals (Sweden)

    Xiaojin Li

    2013-01-01

    Full Text Available Previous studies have investigated both structural and functional brain networks via graph-theoretical methods. However, there is an important issue that has not been adequately discussed before: what is the optimal theoretical graph model for describing the structural networks of human brain? In this paper, we perform a comparative study to address this problem. Firstly, large-scale cortical regions of interest (ROIs are localized by recently developed and validated brain reference system named Dense Individualized Common Connectivity-based Cortical Landmarks (DICCCOL to address the limitations in the identification of the brain network ROIs in previous studies. Then, we construct structural brain networks based on diffusion tensor imaging (DTI data. Afterwards, the global and local graph properties of the constructed structural brain networks are measured using the state-of-the-art graph analysis algorithms and tools and are further compared with seven popular theoretical graph models. In addition, we compare the topological properties between two graph models, namely, stickiness-index-based model (STICKY and scale-free gene duplication model (SF-GD, that have higher similarity with the real structural brain networks in terms of global and local graph properties. Our experimental results suggest that among the seven theoretical graph models compared in this study, STICKY and SF-GD models have better performances in characterizing the structural human brain network.

  3. Exploring the relationship between protein secondary structures, temperature-dependent viscosities, and technological treatments in egg yolk and LDL by FTIR and rheology.

    Science.gov (United States)

    Blume, K; Dietrich, K; Lilienthal, S; Ternes, W; Drotleff, A M

    2015-04-15

    Egg yolk and its main component, low-density lipoproteins (LDL), were consecutively pasteurised, optimally freeze-dried, and dispersed in various NaCl solutions (0-10%). Heat-induced changes in the protein secondary structures which accompanied viscosity-increasing aggregation processes were monitored using Fourier transform infrared spectroscopy (FTIR) to determine the intensities of intermolecular β-sheets (1622 cm(-1)) and results were compared with the temperature-dependent viscosities. Considerable changes in secondary structures observed after reconstitution of freeze-dried LDL had no detectable effect on the characteristic heat-induced viscosity curves but suggest that LDL plays a particular role in the unwanted gel formation of egg yolk after conventional freezing. For all egg yolk samples and all NaCl-containing LDL samples, the sigmoidal changes in the absorbance units vs. temperature curves corresponded with the first increase in heat-induced viscosity. Both analytical methods showed that the presence of ionic strength caused a shift in curve progressions towards higher temperatures, indicating increased thermal stability. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. FT-IR, FT-Raman and UV spectral investigation: computed frequency estimation analysis and electronic structure calculations on chlorobenzene using HF and DFT.

    Science.gov (United States)

    Govindarajan, M; Karabacak, M; Udayakumar, V; Periandy, S

    2012-03-01

    In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100-4000 cm(-1) and 400-4000 cm(-1) respectively, for the title molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartree Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The effects due to the substitution of halogen bond were investigated. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), and thermodynamic properties were performed. The thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between heat capacity (C), entropy (S), and enthalpy changes (H) and temperatures. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. FT-IR, FT-Raman and UV spectral investigation: computed frequency estimation analysis and electronic structure calculations on 1-bromo-2-methylnaphthalene.

    Science.gov (United States)

    Govindarajan, M; Karabacak, M

    2013-01-15

    In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100-4000 cm(-1) and 400-4000 cm(-1) respectively, for 1-bromo-2-methylnaphthalene (C11H9Br) molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based density functional theory (DFT) and ab initio HF methods with different basis sets combinations. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The results of the calculations were applied to simulated vibrational spectra of the title compound, which show excellent agreement with observed spectra. The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. In addition, molecular electrostatic potential and nonlinear optical and thermodynamic properties of the title compound were performed. Mulliken charges and NBOs of the title molecule were also calculated and interpreted. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Theoretical Methods of Domain Structures in Ultrathin Ferroelectric Films: A Review

    Directory of Open Access Journals (Sweden)

    Jianyi Liu

    2014-09-01

    Full Text Available This review covers methods and recent developments of the theoretical study of domain structures in ultrathin ferroelectric films. The review begins with an introduction to some basic concepts and theories (e.g., polarization and its modern theory, ferroelectric phase transition, domain formation, and finite size effects, etc. that are relevant to the study of domain structures in ultrathin ferroelectric films. Basic techniques and recent progress of a variety of important approaches for domain structure simulation, including first-principles calculation, molecular dynamics, Monte Carlo simulation, effective Hamiltonian approach and phase field modeling, as well as multiscale simulation are then elaborated. For each approach, its important features and relative merits over other approaches for modeling domain structures in ultrathin ferroelectric films are discussed. Finally, we review recent theoretical studies on some important issues of domain structures in ultrathin ferroelectric films, with an emphasis on the effects of interfacial electrostatics, boundary conditions and external loads.

  7. Experimental and theoretical (FT-IR, FT-Raman, UV-vis, NMR) spectroscopic analysis and first order hyperpolarizability studies of non-linear optical material: (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one using density functional theory.

    Science.gov (United States)

    Kumar, Amit; Deval, Vipin; Tandon, Poonam; Gupta, Archana; Deepak D'silva, E

    2014-09-15

    A combined experimental and theoretical investigation on FT-IR, FT-Raman, NMR, UV-vis spectra of a chalcone derivative (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one (4N4MSP) has been reported. 4N4MSP has two planar rings connected through conjugated double bond and it provides a necessary configuration to show non-linear optical (NLO) response. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set combination. The analysis of the fundamental modes was made with the help of potential energy distribution (PED). Molecular electrostatic potential (MEP) surface was plotted over the geometry primarily for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The delocalization of electron density of various constituents of the molecule has been discussed with the aid of NBO analysis. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were calculated by time-dependent density functional theory (TD-DFT) and the results complement the experimental findings. The recorded and calculated 1H chemical shifts in gas phase and MeOD solution are gathered for reliable calculations of magnetic properties. Thermodynamic properties like heat capacity (C°p,m), entropy (S°m), enthalpy (H°m) have been calculated for the molecule at the different temperatures. Based on the finite-field approach, the non-linear optical (NLO) parameters such as dipole moment, mean polarizability, anisotropy of polarizability and first order hyperpolarizability of 4N4MSP molecule are calculated. The predicted first hyperpolarizability shows that the molecule has a reasonably good nonlinear optical (NLO) behavior. Copyright © 2014 Elsevier B.V. All

  8. Synthesis, crystal structure, biological activity and theoretical calculations of novel isoxazole derivatives

    Science.gov (United States)

    Jin, R. Y.; Sun, X. H.; Liu, Y. F.; Long, W.; Chen, B.; Shen, S. Q.; Ma, H. X.

    2016-01-01

    Series of isoxazole derivatives were synthesized by substituted chalcones and 2-chloro-6-fluorobenzene formaldehyde oxime with 1,3-dipolar cycloaddition. The target compounds were determined by melting point, IR, 1H NMR, elemental analyses and HRMS. The crystal structure of compound 3a was detected by X-ray diffraction and it crystallizes in the triclinic space group p2(1)/c with z = 4. The molecular geometry of compound 3a was optimized using density functional theory (DFT/B3LYP) method with the 6-31G+(d,p) basis set in the ground state. From the optimized geometry of the molecule, FT-IR, FT-Raman, HOMO-LUMO and natural bond orbital (NBO) were calculated at B3LYP/6-31G+(d,p) level. Finally, the antifungal activity of the synthetic compounds were evaluated against Pythium solani, Gibberella nicotiancola, Fusarium oxysporium f.sp. niveum and Gibberella saubinetii.

  9. Molecular structure, vibrational analysis (FT-IR, FT-Raman), NMR, UV, NBO and HOMO-LUMO analysis of N,N-Diphenyl Formamide based on DFT calculations.

    Science.gov (United States)

    Mathammal, R; Monisha, N R; Yasaswini, S; Krishnakumar, V

    2015-03-15

    In this work, the vibrational spectral analysis is carried out by using Raman and infrared spectroscopy in the range 4000-400 cm(-1) and 4000-50 cm(-1) respectively for N,N-Diphenyl Formamide (DPF) molecule. The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments, nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-VIS) spectra of the title molecule are evaluated using density functional theory (DFT) with standard B3LYP/6-31G(d,p) basis set. The harmonic vibrational frequencies are calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The stability of the molecule arising from hyper conjugative interactions and the charge delocalization has been analyzed using natural bond (NBO) analysis. The possible electronic transitions are determined by HOMO-LUMO orbital shapes and their energies. Thermodynamic properties (heat capacity, entropy and enthalpy) and the first hyperpolarizability of the title compound are calculated. The Mulliken charges and electric dipole moment of the molecule are computed using DFT calculations. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shift of the molecules are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Theoretical and spectroscopic investigations on the structure and bonding in B-C-N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bengu, Erman, E-mail: bengu@fen.bilkent.edu.t [Bilkent University, Department of Chemistry, Ankara (Turkey); Genisel, Mustafa F. [Bilkent University, Department of Chemistry, Ankara (Turkey); Gulseren, Oguz; Ovali, Rasim [Bilkent University, Department of Physics, Ankara (Turkey)

    2009-12-31

    In this study, we have synthesized boron, carbon, and nitrogen containing films using RF sputter deposition. We investigated the effects of deposition parameters on the chemical environment of boron, carbon, and nitrogen atoms inside the films. Techniques used for this purpose were grazing incidence reflectance-Fourier-transform infrared spectroscopy (GIR-FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). GIR-FTIR experiments on the B-C-N films deposited indicated presence of multiple features in the 600 to 1700 cm{sup -1} range for the infrared (IR) spectra. Analysis of the IR spectra, XPS and the corresponding EELS data from the films has been done in a collective manner. The results from this study suggested even under nitrogen rich synthesis conditions carbon atoms in the B-C-N films prefer to be surrounded by other carbon atoms rather than boron and/or nitrogen. Furthermore, we have observed a similar behavior in the chemistry of B-C-N films deposited with increasing substrate bias conditions. In order to better understand these results, we have compared and evaluated the relative stability of various nearest-neighbor and structural configurations of carbon atoms in a single BN sheet using DFT calculations. These calculations also indicated that structures and configurations that increase the relative amount of C-C bonding with respect to B-C and/or C-N were energetically favorable than otherwise. As a conclusion, carbon tends to phase-segregate in to carbon clusters rather than displaying a homogeneous distribution for the films deposited in this study under the deposition conditions studied.

  11. The vibrational structure of (E,E’)-1,4-diphenyl-1,3-butadiene. Linear dichroism FTIR spectroscopy and quantum chemical calculations

    DEFF Research Database (Denmark)

    Hansen, Bjarke Knud Vilster; Møller, Søren; Spanget-Larsen, Jens

    2006-01-01

    The title compound (DPB) was investigated by FTIR spectroscopy in liquid solutions and by FTIR linear dichroism (LD) measurements on samples aligned in stretched polyethylene. The LD data provided experimental assignments of molecular transition moment directions and vibrational symmetries for mo...... of a nearly complete assignment of the IR active fundamentals of DPB, involving reassignment of a number of transitions. In addition, previously published Raman spectra of DPB were well predicted by the B3LYP/cc-pVTZ calculations....

  12. Experimental and theoretical studies on concrete structures with special-shaped shear walls

    Directory of Open Access Journals (Sweden)

    LIU Jianxin

    2014-06-01

    Full Text Available On the basis of concept design and staggered shear panels structure,this paper puts forward a new reinforced concrete high rise biuding structure with special-shaped shear walls and presents an experimental study of the seismic performance of the new special-shaped shear walls structure under low reversed cyclic loading using MTS electro hydraulic servo system.Compared with experimental results,a finite element analysis on this special-shaped shear wall structure,which considers the nonlinearity of concrete structure,is found suitable.It shows that the experimental results fairly confirms to the calculated values,which indicates that this new structure has advantages as good architecture function,big effective space,high overall lateral stiffness,fine ductility,advanced seismic behavior,etc..That is,the close r agreement between the theoretical and experimental results indicates the proposed shear wall structure has wide applications.

  13. Concepts and methods in modern theoretical chemistry electronic structure and reactivity

    CERN Document Server

    Ghosh, Swapan Kumar

    2013-01-01

    Concepts and Methods in Modern Theoretical Chemistry: Electronic Structure and Reactivity, the first book in a two-volume set, focuses on the structure and reactivity of systems and phenomena. A new addition to the series Atoms, Molecules, and Clusters, this book offers chapters written by experts in their fields. It enables readers to learn how concepts from ab initio quantum chemistry and density functional theory (DFT) can be used to describe, understand, and predict electronic structure and chemical reactivity. This book covers a wide range of subjects, including discussions on the followi

  14. Theoretical study of structure of electric field in helical toroidal plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.

    2001-06-01

    A set of transport equations is analyzed, including the bifurcation of the electric field. The structure of the electric field is studied by use of the theoretical model for the anomalous transport diffusivities. The steep gradient of the electric field is obtained at the electric domain. The suppression of the anomalous transport diffusivity is studied in the presence of the strong shear of the electric field. The hard transition with the multiple ambipolar solutions is examined in the structure of the radial electric field. The details of the structure of the electric domain interface are investigated. (author)

  15. Structural changes in 2-diarylthiophene-substituted starburst compounds upon charging: a theoretical and spectroelectrochemical study.

    Science.gov (United States)

    Solc, Roland; Lukes, Vladimír; Rapta, Peter; Hartmann, Horst; Dunsch, Lothar

    2008-12-01

    The role of charging in structural changes of 2-diarylaminothiophene-substituted starburst compounds is clarified by combining theoretical and spectroelectrochemical studies. A systematic and comparative theoretical calculation based on density functional theory and semiempirical Austin Model 1 (AM1) calculations is performed on the neutral and charged states of four model tris(5-diarylamino-5-thienyl)-terminated starburst compounds with a central triphenylamine and 1,3,5-triphenylbenzene moiety. Our results indicate that the charging of molecules leads to structural changes by quinoid-type components mostly on the dendrimers terminated by phenothiazinyl fragments. Based on the optimal geometries, the spectroscopic properties were calculated using the semiempirical Zerner's intermediate neglect overlap method. The presented theoretical results and the spin electron distributions of charged states and their spectra are supported by the spectroelectrochemical observations caused by the different electron localization within the studied molecules after charging. The satisfactory agreement between theoretical electronic transitions and experimental values indicates that a rational design of tunable molecular layers in organic devices based on the starburst compounds described is possible.

  16. Experimental and theoretical evidence for the chaotic dynamics of complex structures

    International Nuclear Information System (INIS)

    Agop, M; Dimitriu, D G; Poll, E; Niculescu, O; Radu, V

    2013-01-01

    This paper presents the experimental results on the formation, dynamics and evolution towards chaos of complex space charge structures that emerge in front of a positively biased electrode immersed in a quiescent plasma. In certain experimental conditions, we managed to obtain the so-called multiple double layers (MDLs) with non-concentric configuration. Our experiments show that the interactions between each MDL's constituent entities are held responsible for the complex dynamics and eventually for its transition to chaos through cascades of spatio-temporal sub-harmonic bifurcations. Further, we build a theoretical model based on the fractal approximation (scale relativity theory) in order to reproduce the experimental results (plasma self-structuring and scenario of evolution to chaos). Comparing the experimental results with the theoretical ones, we observe a good correlation between them. (paper)

  17. Synthesis, structural characterization, crystal structure and theoretical study of a Pd(II)-salen complex with propylene linkage

    Science.gov (United States)

    Azam, Mohammad; Al-Resayes, Saud I.; Soliman, Saied M.; Kruszynska, Agata Trzesowska; Kruszynski, Rafal

    2017-06-01

    A Pd(II)-salen complex derived from salen ligand is reported. The reported complex is investigated by microanalyses (C, H, N), ESI-MS spectrometry, FT-IR, 1H and 13C NMR and UV/Vis spectroscopic studies. In addition, crystal structure measurement study has also been carried out in order to confirm the structure of Pd(II)-salen complex. In order to explore the insights into the structural bonding of the studied complex, computational measurements has been carried out. Combined topology and NBO studies were made to explore the nature of Pdsbnd O and Pdsbnd N bonding in the complex. The natural charges showed that the transfers of the negative charge from the ligand to palladium atom is at 1.4157-1.4312 e. Atom in a molecule (AIM) analysis showed the electron density (ρ(r) > 0.1) and its Laplacian (∇2 ρ(r) > 0). These topological parameters showed that covalent bonding interactions are dominant in Pdsbnd N and Pdsbnd O bonds. However, Pdsbnd N bonds have more covalent characters than Pdsbnd O bonds, which is further confirmed by the ratio of local electron potential energy density to the local electron kinetic energy density (|V(r)|/G(r)) found to be higher for Pdsbnd N bonds (1.1683-1.1993) as compared to Pdsbnd O bonds (1.0689-1.0926). AIM and NBO reveal that shorter Pdsbnd N and Pdsbnd O bonds have higher interaction energies (Eint) and hence higher bond covalence.

  18. A theoretical ovary position in link with the global anatomical structure of each human female body

    OpenAIRE

    Hassen Chaabani

    2013-01-01

    Generally the position of different organs is determined by simple description following the anatomical elements surrounded them and such description could be developed and applied in surgical anatomy. Here, I present for the first time a theoretical three-dimensional ovary position in link with the global anatomical structure of each human female body. I advance the fact that ovaries are placed between two anatomical planes: a first plane of a frontal section touching at the top the internal...

  19. Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as an Analytical Method to Investigate the Secondary Structure of a Model Protein Embedded in Solid Lipid Matrices.

    Science.gov (United States)

    Zeeshan, Farrukh; Tabbassum, Misbah; Jorgensen, Lene; Medlicott, Natalie J

    2018-02-01

    Protein drugs may encounter conformational perturbations during the formulation processing of lipid-based solid dosage forms. In aqueous protein solutions, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can investigate these conformational changes following the subtraction of spectral interference of solvent with protein amide I bands. However, in solid dosage forms, the possible spectral contribution of lipid carriers to protein amide I band may be an obstacle to determine conformational alterations. The objective of this study was to develop an ATR FT-IR spectroscopic method for the analysis of protein secondary structure embedded in solid lipid matrices. Bovine serum albumin (BSA) was chosen as a model protein, while Precirol AT05 (glycerol palmitostearate, melting point 58 ℃) was employed as the model lipid matrix. Bovine serum albumin was incorporated into lipid using physical mixing, melting and mixing, or wet granulation mixing methods. Attenuated total reflection FT-IR spectroscopy and size exclusion chromatography (SEC) were performed for the analysis of BSA secondary structure and its dissolution in aqueous media, respectively. The results showed significant interference of Precirol ATO5 with BSA amide I band which was subtracted up to 90% w/w lipid content to analyze BSA secondary structure. In addition, ATR FT-IR spectroscopy also detected thermally denatured BSA solid alone and in the presence of lipid matrix indicating its suitability for the detection of denatured protein solids in lipid matrices. Despite being in the solid state, conformational changes occurred to BSA upon incorporation into solid lipid matrices. However, the extent of these conformational alterations was found to be dependent on the mixing method employed as indicated by area overlap calculations. For instance, the melting and mixing method imparted negligible effect on BSA secondary structure, whereas the wet granulation mixing method promoted

  20. Theoretical analysis, infrared and structural investigations of energy dissipation in metals under cyclic loading

    International Nuclear Information System (INIS)

    Plekhov, O.A.; Saintier, N.; Palin-Luc, T.; Uvarov, S.V.; Naimark, O.B.

    2007-01-01

    The infrared and structural investigations of energy dissipation processes in metals subjected to cyclic loading have given impetus to the development of a new thermodynamic model with the capability of describing the energy balance under plastic deformation. The model is based on the statistical description of the mesodefect ensemble evolution and its influence on the dissipation ability of the material. Constitutive equations have been formulated for plastic and structural strains, which allow us to describe the stored and dissipated parts of energy under plastic flow. Numerical results indicate that theoretical predictions are in good agreement with the experimentally observed temperature data

  1. A theoretical probe of high-valence uranium and transuranium silylamides: Structural and redox properties

    Science.gov (United States)

    Zhong, Yu-Xi; Guo, Yuan-Ru; Pan, Qing-Jiang

    2016-02-01

    Relativistic density functional theory was used to explore the structural and redox properties of 18 prototypical actinyl silylamides including a variation of metals (U, Np and Pu), metal oxidation states (VI and V) and equatorial ligands. A theoretical approach associated with implicit solvation and spin-orbit/multiplet corrections was proved to be reliable. A marked shift of reduction potentials of actinyl silylamides caused by changes of equatorial coordination ligands and implicit solvation was elucidated by analyses of electronic structures and single-electron reduction mechanism.

  2. Classification and structural analysis of live and dead salmonella cells using fourier transform infrared (FT-IR) spectroscopy and principle component analysis (PCA)

    Science.gov (United States)

    Fourier Transform Infrared Spectroscopy (FT-IR) was used to detect Salmonella typhimurium and Salmonella enteritidis foodborne bacteria and distinguish between live and dead cells of both serotypes. Bacteria were loaded individually on the ZnSe Attenuated Total Reflection (ATR) crystal surface and s...

  3. A set-theoretic approach to linguistic feature structures and unification algorithms (I

    Directory of Open Access Journals (Sweden)

    N. Curteanu

    2000-10-01

    Full Text Available The paper proposes formal inductive definitions for linguistic feature structures (FSs taking values within a class of value types or sorts: single, disjunctive, (ordered lists, multisets (or bags, po-multisets (multisets embedded into a partially ordered set, and indexed (re-entrance values. The linguistic realization (semantics of the considered sorts is proposed. The FSs having these multi-sort values are organized as (rooted directed acyclic graphs. The concrete model of the FSs we had in mind for our set-theoretic definitions are the FSs used within the well-known HPSG linguistic theory. Set-theoretic general definitions for the proposed multi-sort FSs are defined. These constructive definitions start from atomic values and build recurrently multi-sorted values and structures, providing naturally a fixed-point semantics of the obtained FSs as a counterpart to the large class of logical semantics models on FSs. The linguistic unification algorithm based on tableau-subsumption is outlined. The Prolog code of the unification algorithm is provided and results of running it on some of the main multi-sort FSs is enclosed in the appendices. We consider the proposed formal approach to FS definitions and unification as necessary steps to set-theoretical implementations of natural language processing systems.

  4. A set-theoretic approach to linguistic feature structures and unification algorithms (II

    Directory of Open Access Journals (Sweden)

    N.Curteanu

    2001-02-01

    Full Text Available The paper proposes formal inductive definitions for linguistic feature structures (FSs taking values within a class of value types or sorts: single, disjunctive, (ordered lists, multisets (or bags, po-multisets (multisets embedded into a partially ordered set, and indexed (re-entrance values. The linguistic realization (semantics of the considered sorts is proposed. The FSs having these multi-sort values are organized as (rooted directed acyclic graphs. The concrete model of the FSs we had in mind for our set-theoretic definitions are the FSs used within the well-known HPSG linguistic theory. Set-theoretic general definitions for the proposed multi-sort FSs are defined. These constructive definitions start from atomic values and build recurrent multi-sorted values and structures, providing naturally a fixed-point semantics of the obtained FSs as a counterpart to the large class of logical semantics models on FSs. The linguistic unification algorithm based on tableau-subsumption is outlined. The Prolog code of the unification algorithm is provided and results of running it on some of the main multi-sort FSs is enclosed in the appendices. We consider the proposed formal approach to FSs definitions and unification as necessary steps to set-theoretical implementations of natural language processing systems.

  5. The structural, electronic and spectroscopic properties of 4FPBAPE molecule: Experimental and theoretical study

    Science.gov (United States)

    Tanış, Emine; Babur Sas, Emine; Kurban, Mustafa; Kurt, Mustafa

    2018-02-01

    The experimental and theoretical study of 4-Formyl Phenyl Boronic Acid Pinacol Ester (4FPBAPE) molecule were performed in this work. 1H, 13C NMR and UV-Vis spectra were tested in dimethyl sulfoxide (DMSO). The structural, spectroscopic properties and energies of 4FPBAPE were obtained for two potential conformers from density functional theory (DFT) with B3LYP/6-311G (d, p) and CAM-B3LYP/6-311G (d, p) basis sets. The optimal geometry of those structures was obtained according to the position of oxygen atom upon determining the scan coordinates for each conformation. The most stable conformer was found as the A2 form. The fundamental vibrations were determined based on optimized structure in terms of total energy distribution. Electronic properties such as oscillator strength, wavelength, excitation energy, HOMO, LUMO and molecular electrostatic potential and structural properties such as radial distribution functions (RDF) and probability density depending on coordination number are presented. Theoretical results of 4-FPBAPE spectra were found to be compatible with observed spectra.

  6. Theoretical investigations on the structure and potential binding sites of antineoplaston A10 and experimental findings.

    Science.gov (United States)

    Michalska, D

    1990-01-01

    The essential biological importance of antineoplastons has motivated the present theoretical and experimental studies on the structure and potential binding sites of Antineoplaston A10, 3-phenylacetylamino-2,6-piperidinedione. Semi-empirical molecular orbital calculations SCF-LCAO-MO were performed using the MNDO method. The calculated molecular geometry of A10 is in very good agreement with the recently obtained X-ray structure of synthetic A10. Experimental investigations of the Raman spectra of A10 and its N,N-dideuterated derivative confirm the theoretical predictions concerning the structure and hydrogen bonding of A10. Analysis of calculated charge distribution reveals that the negative charges are localized on the ring nitrogen and on the exocyclic oxygen atoms of A10 and are similar to the corresponding charges computed for some pyrimidine bases. This indicates that Antineoplaston A10 may have similar binding sites. It is concluded that the mechanism of action of Antineoplaston A10 may in part be related to its structural and chemical resemblance with deoxythymidine and uridine. A10 may act as a nucleoside antagonist and interact very closely with adenosine units in nucleic acids and enzymes, which may interfere with protein synthesis in neoplastic cells.

  7. Online channel operation mode: Game theoretical analysis from the supply chain power structure

    Directory of Open Access Journals (Sweden)

    Song Huang

    2015-11-01

    Full Text Available Purpose: Dual-channels have been widely used in practice, and the pricing decisions and the online channel operation mode choice have been the core problems in dual-channel supply chain management. This paper focuses on the online channel operation mode choice from the supply chain power structures based on game theoretical analysis. Design/methodology/approach: This paper utilizes three kinds of game theoretical models to analyze the impact of supply chain power structures on the optimal pricing and online channel operation mode choice. Findings: Results derived in this paper indicate that when the self-price elasticity is large, the power structures have no direct impact on the decisions. However, when the self-price elasticity is small and customers’ preference for the online channel is low, then in the MS market, it is better for the retailer to operate the online channel, while in the RS market or in the VN market, it is better for the manufacturer to operate the online channel. Research limitations/implications: In this paper, we do not consider stochastic demand and asymmetric information, which may not well suit the reality. Originality/value: This paper provides a different perspective to analyze the impact of supply chain power structures on the pricing decisions and online channel operation mode choice. The comparison of these two online channel operation modes in this paper is also a unique point.

  8. Theoretical and Empirical Review of Asset Pricing Models: A Structural Synthesis

    Directory of Open Access Journals (Sweden)

    Saban Celik

    2012-01-01

    Full Text Available The purpose of this paper is to give a comprehensive theoretical review devoted to asset pricing models by emphasizing static and dynamic versions in the line with their empirical investigations. A considerable amount of financial economics literature devoted to the concept of asset pricing and their implications. The main task of asset pricing model can be seen as the way to evaluate the present value of the pay offs or cash flows discounted for risk and time lags. The difficulty coming from discounting process is that the relevant factors that affect the pay offs vary through the time whereas the theoretical framework is still useful to incorporate the changing factors into an asset pricing models. This paper fills the gap in literature by giving a comprehensive review of the models and evaluating the historical stream of empirical investigations in the form of structural empirical review.

  9. Organic compounds containing methoxy and cyanoacrylic acid: Synthesis, characterization, crystal structures, and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Khalaji, A. D., E-mail: alidkhalaji@yahoo.com [Golestan University, Department of Chemistry, Faculty of Science (Iran, Islamic Republic of); Maddahi, E. [Iran University of Science & Technology, Ms.C Educated, Department of Chemistry (Iran, Islamic Republic of); Dusek, M.; Fejfarova, K. [Institute of Physics of the ASCR, v.v.i. (Czech Republic); Chow, T. J. [Academia Sinica, Institute of Chemistry (China)

    2015-12-15

    Metal-free organic compounds 24-SC ((E)-2-cyano-3-(2,4-dimethoxyphenyl)acrylic acid) and 34-SC ((E)-2-cyano-3-(3,4-dimethoxyphenyl)acrylic acid), containing methoxy groups as a donor and the acrylic acid as an acceptor were synthesized and characterized by CHN, FT-IR, UV-Vis, {sup 1}H-NMR and single crystal X-ray diffraction and used as photosensitizers for the application of dye-sensitized solar cells (DSSC). The sensitizing characteristics of them were evaluated. Both compounds contain the natural molecule, its anionic form and the piperidinium cation and they differ by number of these molecules in the asymmetric unit. To get further insight into the effect of molecular structure on the performance of DSSC, their geometry and energies of HOMO and LUMO were optimized by density functional theory calculation at the B3LYP/6-31G(d) level with Gaussian 03. Overall conversion efficiencies of 0.78 under full sunlight irradiation are obtained for DSSCs based on the new metal-free organic dyes 24-SC and 34-SC.

  10. Theoretical isotopic fractionation between structural boron in carbonates and aqueous boric acid and borate ion

    Science.gov (United States)

    Balan, Etienne; Noireaux, Johanna; Mavromatis, Vasileios; Saldi, Giuseppe D.; Montouillout, Valérie; Blanchard, Marc; Pietrucci, Fabio; Gervais, Christel; Rustad, James R.; Schott, Jacques; Gaillardet, Jérôme

    2018-02-01

    The 11B/10B ratio in calcite and aragonite is an important proxy of oceanic water pH. However, the physico-chemical mechanisms underpinning this approach are still poorly known. In the present study, we theoretically determine the equilibrium isotopic fractionation properties of structural boron species in calcium carbonates, BO33-, BO2(OH)2- and B(OH)4- anions substituted for carbonate groups, as well as those of B(OH)4- and B(OH)3 species in vacuum. Significant variability of equilibrium isotopic fractionation properties is observed among these structural species which is related to their contrasted coordination state, Bsbnd O bond lengths and atomic-scale environment. The isotopic composition of structural boron does not only depend on its coordination number but also on its medium range environment, i.e. farther than its first coordination shell. The isotopic fractionation between aqueous species and their counterparts in vacuum are assessed using previous investigations based on similar quantum-mechanical modeling approaches. At 300 K, the equilibrium isotope composition of structural trigonal species is 7-15‰ lighter than that of aqueous boric acid molecules, whereas substituted tetrahedral borate ions are heavier than their aqueous counterparts by 10-13‰. Although significant uncertainties are known to affect the theoretical prediction of fractionation factors between solids and solutions, the usually assumed lack of isotopic fractionation during borate incorporation in carbonates is challenged by these theoretical results. The present theoretical equilibrium fractionation factors between structural boron and aqueous species differ from those inferred from experiments which may indicate that isotopic equilibrium, unlike chemical equilibrium, was not reached in most experiments. Further research into the isotopic fractionation processes at the interface between calcium carbonates and aqueous solution as well as long duration experiments aimed at

  11. Theoretical and experimental analysis of photonic structures for fluorescent concentrators with increased efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, Jan Christoph; Peters, Marius; Blaesi, Benedikt; Gombert, Andreas; Glunz, Stefan; Willeke, Gerhard [Fraunhofer Institute for Solar Energy Systems, Freiburg (Germany); Proenneke, Liv [Institut fuer Physikalische Elektronik, Universitaet Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart (Germany); Steidl, Lorenz; Zentel, Rudolf [Institut fuer Organische Chemie, Universitaet Mainz, Duesbergweg 10-14, 55128 Mainz (Germany); Rau, Uwe [IEF-5 Photovoltaik, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2008-12-15

    In this study we present a theoretical and experimental analysis of the application of photonic band stop filters on top of photovoltaic fluorescent concentrators in order to increase the photon collection efficiency. The light guiding effect of the fluorescent concentrator relies on total internal reflection. The escape cone of total internal reflection is their major loss mechanism. Our ray tracing simulation allows to calculate the beneficial effect of photonic band stop reflection filters, which reduce these losses, and to simulate the angular distribution of the light trapped in the concentrator. We present simulations of the optical properties of 1D and 3D photonic structures and how 3D structures are realized with colloidal opals. We also show that the application of a 1D photonic structure increases the efficiency of a real system by 20% relative. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Theoretical Studies of the Electronic Structure of the Compounds of the Actinide Elements

    International Nuclear Information System (INIS)

    Kaltsoyannis, Nikolas; Hay, P.J.; Li, Jun; Blaudeau, Jean-Philippe; Bursten, Bruce E.

    2006-01-01

    In this chapter, we will present an overview of the theoretical and computational developments that have increased our understanding of the electronic structure of actinide-containing molecules and ions. The application of modern electronic structure methodologies to actinide systems remains one of the great challenges in quantum chemistry; indeed, as will be discussed below, there is no other portion of the periodic table that leads to the confluence of complexity with respect to the calculation of ground- and excited-state energies, bonding descriptions, and molecular properties. But there is also no place in the periodic table in which effective computational modeling of electronic structure can be more useful. The difficulties in creating, isolating, and handling many of the actinide elements provide an opportunity for computational chemistry to be an unusually important partner in developing the chemistry of these elements. The importance of actinide electronic structure begins with the earliest studies of uranium chemistry and predates the discovery of quantum mechanics. The fluorescence of uranyl compounds was observed as early as 1833, a presage of the development of actinometry as a tool for measuring photochemical quantum yields. Interest in nuclear fuels has stimulated tremendous interest in understanding the properties, including electronic properties, of small actinide-containing molecules and ions, especially the oxides and halides of uranium and plutonium. The synthesis of uranocene in 1968 led to the flurry of activity in the organometallic chemistry of the actinides that continues today. Actinide organometallics (or organoactinides) are nearly always molecular systems and are often volatile, which makes them amenable to an arsenal of experimental probes of molecular and electronic structure (Marks and Fischer, 1979). Theoretical and computational studies of the electronic structure of actinide systems have developed in concert with the experimental

  13. The phantom derivative method when a structure model is available: about its theoretical basis.

    Science.gov (United States)

    Burla, Maria Cristina; Cascarano, Giovanni Luca; Giacovazzo, Carmelo; Polidori, Giampiero

    2017-05-01

    This study clarifies why, in the phantom derivative (PhD) approach, randomly created structures can help in refining phases obtained by other methods. For this purpose the joint probability distribution of target, model, ancil and phantom derivative structure factors and its conditional distributions have been studied. Since PhD may use n phantom derivatives, with n ≥ 1, a more general distribution taking into account all the ancil and derivative structure factors has been considered, from which the conditional distribution of the target phase has been derived. The corresponding conclusive formula contains two components. The first is the classical Srinivasan & Ramachandran term, relating the phases of the target structure with the model phases. The second arises from the combination of two correlations: that between model and derivative (the first is a component of the second) and that between derivative and target. The second component mathematically codifies the information on the target phase arising from model and derivative electron-density maps. The result is new, and explains why a random structure, uncorrelated with the target structure, adds useful information on the target phases, provided a model structure is known. Some experimental tests aimed at checking if the second component really provides information on ϕ (the target phase) were performed; the favourable results confirm the correctness of the theoretical calculations and of the corresponding analysis.

  14. FT-IR Investigation of the Structural Changes of Sulcis and South Africa Coals under Progressive Heating in Vacuum: Correlation with Volatile Matter

    Directory of Open Access Journals (Sweden)

    Aldo D'Alessio

    2013-01-01

    Full Text Available The analysis of gas evolving during the pyrolysis of two very different rank coals was studied by using FT-IR spectroscopy. These coals, coming from Sulcis (Sardinia, Italy and from South Africa, respectively, were subjected to progressive heating up to 800°C in vacuum. The thermal destruction of coal was followed by monitoring the production of gases in this range of temperature. The gases evolving in the heating from room temperature to 800°C were collected at intervals of 100°C and analysed by infrared spectroscopy. The relative pressures were plotted against temperature. These graphs clearly show the correlation among qualitative gas composition, temperature, and the maximum value of emissions, thus confirming FT-IR analysis as a powerful key for pyrolysis monitoring.

  15. Theoretical Study of Copper Complexes: Molecular Structure, Properties, and Its Application to Solar Cells

    Directory of Open Access Journals (Sweden)

    Jesus Baldenebro-Lopez

    2013-01-01

    Full Text Available We present a theoretical investigation of copper complexes with potential applications as sensitizers for solar cells. The density functional theory (DFT and time-dependent DFT were utilized, using the M06 hybrid meta-GGA functional with the LANL2DZ (D95V on first row and DZVP basis sets. This level of calculation was used to find the optimized molecular structure, the absorption spectra, the molecular orbitals energies, and the chemical reactivity parameters that arise from conceptual DFT. Solvent effects have been taken into account by an implicit approach, namely, the polarizable continuum model (PCM, using the nonequilibrium version of the IEF-PCM model.

  16. Theoretical atomic physics code development I: CATS: Cowan Atomic Structure Code

    International Nuclear Information System (INIS)

    Abdallah, J. Jr.; Clark, R.E.H.; Cowan, R.D.

    1988-12-01

    An adaptation of R.D. Cowan's Atomic Structure program, CATS, has been developed as part of the Theoretical Atomic Physics (TAPS) code development effort at Los Alamos. CATS has been designed to be easy to run and to produce data files that can interface with other programs easily. The CATS produced data files currently include wave functions, energy levels, oscillator strengths, plane-wave-Born electron-ion collision strengths, photoionization cross sections, and a variety of other quantities. This paper describes the use of CATS. 10 refs

  17. Spectral and structural analysis on 2-(4-Allyl-5-Mercapto-4H-1,2,4-Triazol-3-yl)Acetic acid: Experimental and theoretical (HF and DFT) studies

    Science.gov (United States)

    Şen, Fatih; Dinçer, Muharrem; Yilmaz, Ibrahim; Cukurovali, Alaaddin

    2017-06-01

    We examined the structural and spectral features of the title compound through with experimental and electronic structure methods. The crystal and molecular structure of compound has been brought out using single crystal X-ray diffraction. The spectroscopic investigations of the compound were studied by FT-IR and NMR techniques. The FT-IR spectra were recorded in solid phase on a Mattson 1000 in the region 4000-400 cm-1. 1H and 13C NMR spectra were recorded in deuterium oxide (D2O) chloroform solution on a Varian-Mercury-Plus 400 MHz spectrometer. To support experimental results, the structural and spectroscopic data of the molecular geometry which obtained from the X-ray molecular structure in the ground state were optimized by using Hartree-Fock (HF) and Density Functional Theory (DFT/B3LYP) methods with the 6-31+G(d, p) basis set. The calculated structural parameters (bond lengths, bond angles, torsion angles), vibrational assignments and chemical shifts compared with their experimental data. The frontier molecular orbitals (FMOs), molecular electrostatic potential maps (MEP), Mulliken charge analysis and thermodynamic properties of the compound were obtained by theoretical geometries.

  18. Teoretski pogled na razvojne strukture slovenskega podeželja = Theoretical view on the development structures of Slovenian rural space

    Directory of Open Access Journals (Sweden)

    Marijan M. Klemenčič

    2006-01-01

    Full Text Available Theoretical concepts and research problems of contemporary rural space are presented in the first part of the article, following with the attempt of defining the crucial factors of development and basic structures of Slovenian rural space after the 2nd World War as a starting-point for defining theoretically more advanced concepts in Slovenian geography.

  19. Structural adjustment programmes on the African continent : the theoretical foundations of IMF/World Bank reform policies

    NARCIS (Netherlands)

    Meilink, H.A.

    2003-01-01

    Since the early 1980s the majority of countries in sub-Saharan Africa embarked on the implementation of IMF/World Bank designed 'structural adjustment programmes' (SAPs). This paper examines the theoretical underpinnings of the SAPs. It shows that IMF policies are based on a theoretical framework

  20. Theoretical study of the structure and reactivity of lanthanide and actinide based organometallic complexes

    International Nuclear Information System (INIS)

    Barros, N.

    2007-06-01

    In this PhD thesis, lanthanide and actinide based organometallic complexes are studied using quantum chemistry methods. In a first part, the catalytic properties of organo-lanthanide compounds are evaluated by studying two types of reactions: the catalytic hydro-functionalization of olefins and the polymerisation of polar monomers. The reaction mechanisms are theoretically determined and validated, and the influence of possible secondary non productive reactions is envisaged. A second part focuses on uranium-based complexes. Firstly, the electronic structure of uranium metallocenes is analysed. An analogy with the uranyl compounds is proposed. In a second chapter, two isoelectronic complexes of uranium IV are studied. After validating the use of DFT methods for describing the electronic structure and the reactivity of these compounds, it is shown that their reactivity difference can be related to a different nature of chemical bonding in these complexes. (author)

  1. Theoretical and numerical investigations of sub-wavelength diffractive optical structures

    DEFF Research Database (Denmark)

    Dridi, Kim

    2000-01-01

    finite-difference time domain method and exact radiation integrals is implemented for the polarization where the electric field vector is perpendicular to the two dimentional plane of symmetry. The computational model solves the full vectorial time domain Maxwell equations with general sources...... of illumination. Maxwell's equations are solved numerically in complex geometries and radiation integrals are applied in homogeneous regions, thus minimizing the computational time. Analysis of finte length surface relief structures embedded in polymer dielectric waveguides are presented. The importance......The work in this thesis concerns theoretical and numerical investigations of sub-wavelength diffractive optical structures, relying on advanced two-dimensional vectorial numerical models that have applications in Optics and Electromagnetics. Integrated Optics is predicted to play a major role...

  2. Theoretical and experimental investigation of the nonlinear structural dynamics of Fast Breeder Reactor fuel elements

    International Nuclear Information System (INIS)

    Liebe, R.

    1978-04-01

    This study describes theoretical and experimental investigations of the dynamic deformation behavior of single and clustered fuel elements under local fault conditions in a Fast Breeder Reactor core. In particular an energetic molten-fuel-coolant-interaction (FCI) is assumed in one subassembly with corresponding pressure pulses, which may rupture the wrapper and load the adjacent fuel elements impulsively. Associated coherent structural deformation may exceed tolerable and damage the control rods. To attack the outlined coupled fluid-structure-interaction problem it is assumed, that the loading at the structures is known in space and time, and that there is no feedback from the deformation response. Then current FCI-knowledge and experience from underwater core model explosion tests is utilized to estimate upper limits of relevant pulse characteristics. As a first step the static carrying capacity of the rigid-plastic hexagonal wrapper tube is calculated using the methods of limit analysis. Then for a general dynamic simulation of the complete elastoplastic subassembly response the concept of a discrete nonlinear hinge is introduced. A corresponding physical lumped parameter hinge model is presented, and general equations of motion are derived using D'Alembert's principle. Application to the static and dynamic analysis of a single complete fuel element includes the semiempirical modelling of the fuel-pin bundle by a homogeneous compressible medium. Most important conclusions are concerning the capability of the theoretical models, the failure modes and threshold load levels of single as well as clustered SNR-300 fuel elements and the safety relevant finding, that only limited deformations are found in the first row around the incident element. This shows in agreement with explosion test results that the structured and closely spaced fuel elements constitute an effective, inherent barrier against extreme dynamic loadings. (orig.) [de

  3. Computational tools for experimental determination and theoretical prediction of protein structure

    Energy Technology Data Exchange (ETDEWEB)

    O`Donoghue, S.; Rost, B.

    1995-12-31

    This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. The authors intend to review the state of the art in the experimental determination of protein 3D structure (focus on nuclear magnetic resonance), and in the theoretical prediction of protein function and of protein structure in 1D, 2D and 3D from sequence. All the atomic resolution structures determined so far have been derived from either X-ray crystallography (the majority so far) or Nuclear Magnetic Resonance (NMR) Spectroscopy (becoming increasingly more important). The authors briefly describe the physical methods behind both of these techniques; the major computational methods involved will be covered in some detail. They highlight parallels and differences between the methods, and also the current limitations. Special emphasis will be given to techniques which have application to ab initio structure prediction. Large scale sequencing techniques increase the gap between the number of known proteins sequences and that of known protein structures. They describe the scope and principles of methods that contribute successfully to closing that gap. Emphasis will be given on the specification of adequate testing procedures to validate such methods.

  4. Structure of polypropylene/polyethylene blends assessed by polarised PA-FTIR spectroscopy, polarised FT Raman spectroscopy and confocal Raman microscopy

    Czech Academy of Sciences Publication Activity Database

    Schmidt, Pavel; Dybal, Jiří; Ščudla, Jaroslav; Raab, Miroslav; Kratochvíl, Jaroslav; Eichhorn, K. J.; López-Quintana, S.

    2002-01-01

    Roč. 184, - (2002), s. 107-122 ISSN 1022-1360. [European Symposium on Polymer Spectroscopy /14./. Dresden, 02.09.2001-05.09.2001] R&D Projects: GA ČR GA106/97/1071; GA ČR GA203/97/0539; GA AV ČR KSK4050111; GA AV ČR IAA4050904 Institutional research plan: CEZ:AV0Z4050913 Keywords : polypropylene/polyethylene blends * polarized photoacoustic FTIR spectroscopy * confocal Raman microscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.758, year: 2002

  5. Shape-selected nanocrystals for in situ spectro-electrochemistry studies on structurally well defined surfaces under controlled electrolyte transport: A combined in situ ATR-FTIR/online DEMS investigation of CO electrooxidation on Pt

    Science.gov (United States)

    Jusys, Zenonas; Behm, R Jürgen

    2014-01-01

    Summary The suitability and potential of shape selected nanocrystals for in situ spectro-electrochemical and in particular spectro-electrocatalytic studies on structurally well defined electrodes under enforced and controlled electrolyte mass transport will be demonstrated, using Pt nanocrystals prepared by colloidal synthesis procedures and a flow cell set-up allowing simultaneous measurements of the Faradaic current, FTIR spectroscopy of adsorbed reaction intermediates and side products in an attenuated total reflection configuration (ATR-FTIRS) and differential electrochemical mass spectrometry (DEMS) measurements of volatile reaction products. Batches of shape-selected Pt nanocrystals with different shapes and hence different surface structures were prepared and structurally characterized by transmission electron microscopy (TEM) and electrochemical methods. The potential for in situ spectro-electrocatalytic studies is illustrated for COad oxidation on Pt nanocrystal surfaces, where we could separate contributions from two processes occurring simultaneously, oxidative COad removal and re-adsorption of (bi)sulfate anions, and reveal a distinct structure sensitivity in these processes and also in the structural implications of (bi)sulfate re-adsorption on the CO adlayer. PMID:24991511

  6. Structure, isomerism, and vibrational assignment of aluminumtrifluoroacetylacetonate. An experimental and theoretical study

    Science.gov (United States)

    Afzali, R.; Vakili, M.; Boluri, E.; Tayyari, S. F.; Nekoei, A.-R.; Hakimi-Tabar, M.; Darugar, V.

    2018-02-01

    An interpretation of the experimental IR and Raman spectra of Aluminum (III) trifluoroacetylacetonate (Al(TFAA)3) complex, which were synthesized by us, is first reported here. The charge distribution, isomerism, strength of metal‑oxygen binding and vibrational spectral properties for this complex structure were theoretically investigated through population analysis, geometry optimization and harmonic frequency calculations, performed at B3LYP/6-311G* level of theory. In the population analysis, two different approaches reffered to as ;Atoms in molecules (AIM);, and ;Natural Bond Orbital (NBO); were used. According to the calculation resuls, the energy difference between the cis and trans isomers of Al(TFAA)3 is very small and indicates that both isomers coexist in the sample in comparable proportions. Comparison of the calculated frequency and intensity data with the observed IR and Raman spectra of the complex has supported this conclusion. On the other hand, comparison of the structural and vibrational spectral data of Al(TFAA)3, which were experimentally measured and calculated at B3LYP/6-311G* level, with the corresponding data of Aluminum acetylacetonate (Al(AA)3) has revealed the effects of CF3 substitution on the structural and vibrational spectral data associated with the CH3 groups in the complex structure.

  7. The structure and dynamics of cities urban data analysis and theoretical modeling

    CERN Document Server

    Barthelemy, Marc

    2016-01-01

    With over half of the world's population now living in urban areas, the ability to model and understand the structure and dynamics of cities is becoming increasingly valuable. Combining new data with tools and concepts from statistical physics and urban economics, this book presents a modern and interdisciplinary perspective on cities and urban systems. Both empirical observations and theoretical approaches are critically reviewed, with particular emphasis placed on derivations of classical models and results, along with analysis of their limits and validity. Key aspects of cities are thoroughly analyzed, including mobility patterns, the impact of multimodality, the coupling between different transportation modes, the evolution of infrastructure networks, spatial and social organisation, and interactions between cities. Drawing upon knowledge and methods from areas of mathematics, physics, economics and geography, the resulting quantitative description of cities will be of interest to all those studying and r...

  8. Theoretical studies on the structures and detonation properties of nitramine explosives containing benzene ring.

    Science.gov (United States)

    Zhao, GuoZheng; Lu, Ming

    2012-06-01

    The nitramine compounds containing benzene ring were optimized to obtain their molecular geometries and electronic structures at DFT-B3LYP/6-31+G(d) level. The theoretical molecular density (ρ), heat of formation (HOF), energy gap (ΔE(LUMO-HOMO)), charge on the nitro group (-Q(NO2)), detonation velocity (D) and detonation pressure (P), estimated using Kamlet-Jacobs equations, showed that the detonation properties of these compounds were excellent. It is found that there are good linear relationships between density, heat of formation, detonation velocity, detonation pressure and the number of nitro group. The simulation results reveal that molecule G performs similarly to famous explosive HMX, and molecule H outperforms HMX. According to the quantitative standard of energetics as an HEDC (high energy density compound), molecule H essentially satisfies this requirement. These results provide basic information for molecular design of novel high energetic density compounds.

  9. Characterization of electronic structure and physicochemical properties of antiparasitic nifurtimox analogues: A theoretical study

    Science.gov (United States)

    Soriano-Correa, Catalina; Raya, A.; Esquivel, Rodolfo O.

    American trypanosomiasis, also known as Chagas' disease, is caused by Trypanosoma cruzi (T. cruzi). It is well known that trypanosomes, and particularly T. cruzi, are highly sensitive towards oxidative stress, i.e., to compounds than are able to produce free radicals. Generally, nifurtimox (NFX) and benznidazol are most effective in the acute phase of the disease; therefore, nitroheterocycles constitute good models to design other nitrocompounds with specific biological characteristics. Thus, we have performed an ab initio study at the Hartree-Fock and Density Functional Theory levels of theory of several NFX analogues recently synthesized, to characterize them by obtaining their electronic, structural, and physicochemical properties, which might be linked to the observed antichagasic activity. The antitrypanosomal activity scale previously reported for the NFX analogues studied in this work is in good agreement with our theoretical results, from which we can conclude that the activity seems to be related to the reactivity along with the acidity observed for the most active molecules.

  10. Experimental and theoretical analyses of package-on-package structure under three-point bending loading

    International Nuclear Information System (INIS)

    Jia Su; Wang Xi-Shu; Ren Huai-Hui

    2012-01-01

    High density packaging is developing toward miniaturization and integration, which causes many difficulties in designing, manufacturing, and reliability testing. Package-on-Package (PoP) is a promising three-dimensional high-density packaging method that integrates a chip scale package (CSP) in the top package and a fine-pitch ball grid array (FBGA) in the bottom package. In this paper, in-situ scanning electron microscopy (SEM) observation is carried out to detect the deformation and damage of the PoP structure under three-point bending loading. The results indicate that the cracks occur in the die of the top package, then cause the crack deflection and bridging in the die attaching layer. Furthermore, the mechanical principles are used to analyse the cracking process of the PoP structure based on the multi-layer laminating hypothesis and the theoretical analysis results are found to be in good agreement with the experimental results. (condensed matter: structural, mechanical, and thermal properties)

  11. Influence of the Nd{sup 3+} ions content on the FTIR and the visible up-conversion luminescence properties of nano-structure BaTiO{sub 3}, prepared by sol-gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, A.G.A. [National Research Center (NRC), Department of Solid State Physics, Cairo (Egypt); Badr, Y. [National Institute of Laser Enhancement Sciences (NILES), Cairo University (Egypt); El Shaarawy, M.; Shash, N.M.H. [Physics Department, Faculty of Science, Banha University (Egypt); Battisha, I.K., E-mail: szbasha@yahoo.co [National Research Center (NRC), Department of Solid State Physics, Cairo (Egypt)

    2010-01-21

    The nano-structure BaTiO{sub 3} (BT) powder doped with different concentrations of Nd{sup 3+} ions were annealed at 750 {sup o}C for 1 h to form nano-structure tetragonal phase of BT powder. The structure properties studied using XRD and FTIR methods. Sensitized up-conversion luminescence observed under excitation of 808 nm diode laser, suggesting that the Nd{sup 3+} ions-doped BT might be an ideal up-conversion material for infrared excitation. The influence of increasing the concentration of the Nd{sup 3+} ions on the luminescence intensity investigated using laser diode. The up-conversion mechanisms in the doped system will be discussed by analyzing the energy level structures of the Nd{sup 3+} ions.

  12. Theoretical studies of the electronic structure of the ions KCs+ and RbCs+

    International Nuclear Information System (INIS)

    Abdul Al, Saleh Nabhan

    2000-01-01

    Author.the theoretical investigation of the electronic structure of the molecular ions KCs + and RbCs + , by using ab initio calculation, is being considered. Some of the approximation methods may form a theoretical model; with which many physical properties of molecular systems can be explored by once a mathematical procedure has been implanted through a computer program. This theoretical structure is referred to as ab initio electronic structure. The Hamiltonian for a multi-electron system cannot be separated into one-electron parts without making the independent electron approximation. The one-electron molecular wave function is referred to as molecular orbital (MO). The MOs may be expressed as linear combinations of atomic orbitals. Making the Born-Oppenheimer approximation, we seek to solve for the electronic eigenfunctions and eigenvalues with the nuclei fixed at various separation distances. A rigorous variational calculation on a system involves the following steps: write down the Hamiltonian operator for the system; Select some mathematical functional form ψ as the trial wave function. This form should have variable parameters (we take ψto be made up of Slater determinants containing molecular-spin orbitals); Minimize the average value of the energy (E) with respect to variations in the parameters. We describe an approach in the ab initio calculations, called the self-consistent field (SCF) method. The Hartree-Fock equation is obtained by requiring E to be stationary with respect to variations in ψ. The best MOs are eigenfunctions of the Fock operator. The instantaneous part of the interaction that SCF neglects is referred to as electron correlation. One general technique, for including the effects of correlation, is called configuration interaction (CI). Moeller-Plesset perturbation theory is an alternative approach to the correlation problem. The calculation has been performed for the two molecular ions, through the CI PSI (Configuration Interaction

  13. FTIR spectroscopy supported by statistical techniques for the structural characterization of plastic debris in the marine environment: Application to monitoring studies.

    Science.gov (United States)

    Mecozzi, Mauro; Pietroletti, Marco; Monakhova, Yulia B

    2016-05-15

    We inserted 190 FTIR spectra of plastic samples in a digital database and submitted it to Independent Component Analysis (ICA) to extract the "pure" plastic polymers present. These identified plastics were polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), high density polyethylene terephthalate (HDPET), low density polyethylene terephthalate (LDPET), polystyrene (PS), Nylon (NL), polyethylene oxide (OPE), and Teflon (TEF) and they were used to establish the similarity with unknown plastics using the correlation coefficient (r), and the crosscorrelation function (CC). For samples with rplastic fragments found in the Carretta carretta, one plastic sample was assigned to OPE due to its r=0.87; for all the other three plastic samples, due to the r values ranging between 0.83 and0.70, the support of MD suggested LDPET and OPE as co-polymer constituents. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Phenylacetic acid co-crystals with acridine, caffeine, isonicotinamide and nicotinamide: Crystal structures, thermal analysis, FTIR spectroscopy and Hirshfeld surface analysis

    Science.gov (United States)

    Amombo Noa, Francoise M.; Jacobs, Ayesha

    2017-07-01

    Co-crystals of phenylacetic acid (PAA) with acridine (ACR), caffeine (CAF), isonicotinamide (INM) and nicotinamide (NAM) have been successfully prepared and characterised by single crystal X-ray diffraction, FTIR spectroscopy, thermal analysis and Hirshfeld surface analysis. The ACR, INM and NAM co-crystals with PAA exhibit the carboxylic acid-pyridine heterosynthon. Furthermore the amide-amide supramolecular homosynthon is observed in the PAA co-crystals with INM and NAM as well as Nsbnd H⋯O interactions between the acid and the respective base. The CAF co-crystal exhibits hydrogen bonding between the imidazole nitrogen and the COOH group of the PAA. The compounds demonstrate different stoichiometries; for PAA·ACR and PAA·INM a 1:1 ratio is displayed, a 2:1 in 2PAA·CAF and a 2:2 in the case of 2PAA·2NAM.

  15. Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations.

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Mavis, Tugba; Eskici, Mustafa; Atac, Ahmet

    2013-11-01

    In this work, FT-IR, FT-Raman, UV and NMR spectra of 3-ethynylthiophene (3-ETP, C6H4S) were carried out by using density functional theory DFT/B3LYP method with the 6-311++G(d,p), 6-311+G(d,p), 6-311G(d,p), 6-31++G(d,p), 6-31+G(d,p), 6-31G(d,p) basis sets. FT-IR and FT-Raman spectra were recorded in the regions of 3500-400cm(-1) and 3500-50cm(-1), respectively. The geometrical parameters, energies and wavenumbers were obtained and the complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The (1)H, (13)C and HMQC ((1)H-(13)C correlation) NMR spectra in chloroform (CDCl3) were recorded and calculated. The UV spectrum of investigated compound were recorded in the region of 200-400nm in ethanol solution. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. The thermodynamic properties such zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment of the studied compound were calculated. As a result, the calculated results were compared with the observed data and found to be in good agreement. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Theoretical Challenges for Distance Education in the 21st Century: A shift from structural to transactional issues

    Directory of Open Access Journals (Sweden)

    Randy Garrison

    2000-06-01

    Full Text Available The premise of this article is that theoretical frameworks and models are essential to the long-term credibility and viability of a field of practice. In order to assess the theoretical challenges facing the field of distance education, the significant theoretical contributions to distance education in the last century are briefly reviewed. This review of distance education as a field of study reveals an early preoccupation with organizational and structural constraints. However, the review also reveals that the theoretical development of the field is progressing from organizational to transactional issues and assumptions. The question is whether distance education has the theoretical foundation to take it into the 21st century and whether distance education theory development will keep pace with innovations in technology and practice.

  17. Spectroscopic and theoretical studies on the structural, electronic, and optical properties of zinc octaethylporphyrin/C60 co-deposited films

    Science.gov (United States)

    Onoe, Jun; Watanabe, Shinta; Kato, Shiro; Nakaya, Masato; Bucher, Jean-Pierre

    2017-12-01

    We have examined the structural, electronic, and optical properties of zinc-octaethylporphyrin [Zn(OEP)]/C60 co-deposited films to elucidate the donor (D)-acceptor (A) interactions at the D/A interface of heterojunction organic solar cells (OSCs), using Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence (PL) spectroscopy in combination with first-principles and semi-empirical calculations. The FT-IR and XRD results indicated that Zn(OEP) and C60 were mixed with each other at the molecular level in the co-deposited film. The theoretical calculations suggested that in the interfacial region, it is energetically preferable for the C60 molecule to face the center of the planar structure of Zn(OEP) at a distance of 2.8 Å rather than the edge of the structure at a distance of 5.0 Å. After consideration of the C60 solvent effects, this coordination model for C60-Zn(OEP) adequately explained the line shift of the UV-vis peaks with respect to the proportion of C60 in the co-deposited films. A comparison of the energy level diagrams of Zn(OEP) before and after the interaction with C60 revealed that the LUMO, HOMO, and HOMO-1 were significantly affected by the interaction with C60. In particular, the HOMO-1 wave function became spread over a portion of C60, although the charge transfer between Zn(OEP) and C60 was almost negligible. Since no PL peaks (S1 → S0) from the excited Soret band of Zn(OEP) were observed for the Zn(OEP)/C60 co-deposited films, the D/A mixing layers played a crucial role in completely dissolving the photogenerated excitons to electrons-hole pairs that cause the short-circuit current, which is relevant to improving the energy conversion efficiency of OSCs.

  18. A large scale analysis of information-theoretic network complexity measures using chemical structures.

    Directory of Open Access Journals (Sweden)

    Matthias Dehmer

    Full Text Available This paper aims to investigate information-theoretic network complexity measures which have already been intensely used in mathematical- and medicinal chemistry including drug design. Numerous such measures have been developed so far but many of them lack a meaningful interpretation, e.g., we want to examine which kind of structural information they detect. Therefore, our main contribution is to shed light on the relatedness between some selected information measures for graphs by performing a large scale analysis using chemical networks. Starting from several sets containing real and synthetic chemical structures represented by graphs, we study the relatedness between a classical (partition-based complexity measure called the topological information content of a graph and some others inferred by a different paradigm leading to partition-independent measures. Moreover, we evaluate the uniqueness of network complexity measures numerically. Generally, a high uniqueness is an important and desirable property when designing novel topological descriptors having the potential to be applied to large chemical databases.

  19. Properties, theoretical study and crystal structure of 3-benzothiazole-9-ethyl carbazole.

    Science.gov (United States)

    Gu, Yingchun; Lin, Dayong; Fei, Xuening; Wang, Cuihong; Li, Ling; Tang, Yalin; Zhou, Jianguo

    2016-09-01

    The title compound of 3-benzothiazole-9-ethyl carbazole was synthesized by the reaction of 3-aldehyde-9-ethyl carbazole and 2-aminothiophenol. The compound was characterized by (1) H nuclear magnetic resonance (NMR) and mass spectrometry (MS). Its crystal structure was obtained and determined by single crystal X-ray diffraction. The results showed that the crystal belongs to the orthorhombic crystal system and the cell parameters of space group P2(1)2(1)2(1) were a = 5.6626 (12) Å, b = 12.606 (3) Å, c = 22.639 (5) Å, α = 90°, β = 90°, γ = 90°, V = 1616.0 (6) Å(3) , Z = 4, Dc = 1.350 mg/m(3) . The UV-vis and fluorescence spectra were also studied preliminarily. The fluorescence spectra of the title compound with bovine serum albumin (BSA) showed that BSA could be marked with the compound and the stability constant between them was 0.82 × 10(7)  M(-1) . Meanwhile, the crystal and molecule were theoretically surveyed by density functional tight-binding (DFTB). The results showed that there was an orbital overlap for lowest unoccupied molecular orbital (LUMO) between the neighbouring molecules for the crystal, which is different from the molecule structure. It was also showed that the crystal structure is a non-conductor. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Experimental (FT-IR and FT-Raman) and theoretical (HF and DFT) investigation, NMR, NBO, electronic properties and frequency estimation analyses on 2,4,5-trichlorobenzene sulfonyl chloride

    Science.gov (United States)

    Gayathri, R.; Arivazhagan, M.

    2012-11-01

    The present work deals with the structural, electronic, and vibrational analyses of the biomolecule 2,4,5-trichlorobenzene sulfonyl chloride (TCBSC). TCBSC is a novel pharmaceutical compound used in dyes, pesticides, pigments, fluorescence brighteners and intermediate for agricultural chemicals in the manufacture of insecticides. Quantum chemical calculation of geometrical structure and energies of TCBSC was carried out by density functional theory (B3LYP) and ab initio (HF) methods at 6-311+G(d,p) and 6-311++G(d,p) standard basis set. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. NMR analysis shows that the isotropic chemical shifts of carbon and hydrogen atom of TCBSC are giving the reasonable shielding to the molecule. Another interesting property shows nonlinear optical (NLO) behavior. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and energy band gap.

  1. FT-IR and FT-Raman, NMR and UV spectroscopic investigation and hybrid computational (HF and DFT) analysis on the molecular structure of mesitylene.

    Science.gov (United States)

    Kose, E; Atac, A; Karabacak, M; Nagabalasubramanian, P B; Asiri, A M; Periandy, S

    2013-12-01

    The spectroscopic properties of mesitylene were investigated by FT-IR, FT-Raman, UV, (1)H and (13)C NMR techniques. The geometrical parameters and energies have been obtained from density functional theory (DFT) B3LYP method and Hartree-Fock (HF) method with 6-311++G(d,p) and 6-311G(d,p) basis sets calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. (13)C and (1)H NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed. Reduced density gradient (RDG) of the mesitylene was also given to investigate interactions of the molecule. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Synthesis, structure and properties of [Zn(L-Tyr)₂(bpy)]₂⋅3H₂O·CH₃OH complex: theoretical, spectroscopic and microbiological studies.

    Science.gov (United States)

    Wojciechowska, Agnieszka; Gągor, Anna; Wysokiński, Rafał; Trusz-Zdybek, Agnieszka

    2012-12-01

    The mixed ligand zinc(II) ion complex of the formula [Zn(l-Tyr)(2)(bpy)](2)·3H(2)O·CH(3)OH (1), where L-Tyr and bpy are moieties of L-tyrosine and 2,2'-bipyridine (2,2'-bpy), has been isolated in a crystalline form. Crystal structure was determined and the spectroscopic (FTIR, Raman and near IR (NIR)-visible (vis)-UV) examinations were conducted. Additionally, the theoretical data of the molecular structure were obtained using the density functional theory (DFT) methods. Crystals of complex 1 adopt hexagonal form with a=b=12.9307 (18)Å, c=30.148 (6)Å and γ=120 lattice parameters, and P3(2)2(1) space group. The crystal structure is built of [Zn(L-Tyr)(2)(bpy)] units and disordered solvent molecules of water and methanol. Each L-tyrosine chelates the zinc(II) ion via carboxylate oxygen and amino nitrogen atoms. The donor atoms form the cis-[ZnN(2)N(2)'O(2)] chromophore with the distorted octahedral geometry around the Zn(2+) ion. Complex 1 as well as [Zn(Im)(L-Tyr)(2)](2)·5H(2)O (2) and {[Zn(L-Tyr)(2)(H(2)O)]·H(2)O}(n) (3) compounds were examined as potential inhibitors of the growth of plant and animal fungi, such as Fusarium solani, Penicillum verrucosum, Aspergillus flavus, and bacterial strains, such as Gram-negative Escherichia coli, Pseudomonas fluorescens, Serratia marcescens and Gram-positive Bacillus subtilis. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. A theoretical inquiry into the question of W and Ta (100) atomic structures

    International Nuclear Information System (INIS)

    Treglia, G.; Spanjaard, D.

    1983-01-01

    In spite of the very large number of experiments (LEED, AES, UPS, MeV He + scattering, work function, FIM) carried out on W (100), no structural model consistent with all the data has been proposed yet: in particular, the question of the reconstruction thermally induced when the sample is cooled below room temperature remains a puzzling problem. Furthermore, from a theoretical point of view, no definitive answer has been given. Actually, either the mechanism invoked for the reconstruction is too weak, or some contributions are omitted or calculated without sufficient care. The surface energy of W (100) is computed taking into account the band term treated in the tight binding approximation, a pairwise repulsive potential of the Born-Mayer type and the electronic correlation contribution obtained from a perturbation treatment of the Hubbard model in the band limit. This energy is then fully minimised with respect to all coordinates of surface atoms, keeping all atoms neutral for any displace,ment. It is found that the unreconstructed surface is the most stable at T = 0 K and discuss this unexpected result. A similar calculation for Ta (100) leads to opposite conclusions. (author)

  4. Research and evaluation of innovative integrated industrial structure potential: theoretical and practical aspects

    Directory of Open Access Journals (Sweden)

    Zdolnikova S.V.

    2017-01-01

    Full Text Available Modern market conditions, as well as the reorientation of the Russian economy from raw materials to the innovative model of development, based, in particular, on strengthening the position of domestic industry being able to compete against the international producers, are the incentives to seek ways to increase efficiency and create additional competitive advantages that at present are innovative products and services. One of the innovative economic entity development factors is the establishment and effective use of its innovative potential. The innovative potential evaluation plays an important role in the development of innovation policy and innovation strategy of market subject activity. This article investigates the innovative potential of the integrated industrial structures (IIS that presently are one of the most promising forms of economic entities integration. The authors propose an approach to the definition and assessment of innovative IIS potential, as well as the comprehensive and systemic innovative potential estimation procedure. The developed theoretical and methodological provisions were applied to evaluate the innovative potential of the JSC Svetlana, one of the leading Russian electronic instrument engineering holdings.

  5. Theoretical study of the electronic structure of f-element complexes by quantum chemical methods

    International Nuclear Information System (INIS)

    Vetere, V.

    2002-09-01

    This thesis is related to comparative studies of the chemical properties of molecular complexes containing lanthanide or actinide trivalent cations, in the context of the nuclear waste disposal. More precisely, our aim was a quantum chemical analysis of the metal-ligand bonding in such species. Various theoretical approaches were compared, for the inclusion of correlation (density functional theory, multiconfigurational methods) and of relativistic effects (relativistic scalar and 2-component Hamiltonians, relativistic pseudopotentials). The performance of these methods were checked by comparing computed structural properties to published experimental data, on small model systems: lanthanide and actinide tri-halides and on X 3 M-L species (X=F, Cl; M=La, Nd, U; L = NH 3 , acetonitrile, CO). We have thus shown the good performance of density functionals combined with a quasi-relativistic method, as well as of gradient-corrected functionals associated with relativistic pseudopotentials. In contrast, functionals including some part of exact exchange are less reliable to reproduce experimental trends, and we have given a possible explanation for this result . Then, a detailed analysis of the bonding has allowed us to interpret the discrepancies observed in the structural properties of uranium and lanthanides complexes, based on a covalent contribution to the bonding, in the case of uranium(III), which does not exist in the lanthanide(III) homologues. Finally, we have examined more sizeable systems, closer to experimental species, to analyse the influence of the coordination number, of the counter-ions and of the oxidation state of uranium, on the metal-ligand bonding. (author)

  6. Railway noise annoyance: exposure-response relationships and testing a theoretical model by structural equation analysis.

    Science.gov (United States)

    Pennig, Sibylle; Schady, Arthur

    2014-01-01

    In some regions the exposure to railway noise is extremely concentrated, which may lead to high residential annoyance. Nonacoustical factors contribute to these reactions, but there is limited evidence on the interrelations between the nonacoustical factors that influence railway noise annoyance. The aims of the present study were (1) to examine exposure-response relationships between long-term railway noise exposure and annoyance in a region severely affected by railway noise and (2) to determine a priori proposed interrelations between nonacoustical factors by structural equation analysis. Residents (n = 320) living close to railway tracks in the Middle Rhine Valley completed a socio-acoustic survey. Individual noise exposure levels were calculated by an acoustical simulation model for this area. The derived exposure-response relationships indicated considerably higher annoyance at the same noise exposure level than would have been predicted by the European Union standard curve, particularly for the night-time period. In the structural equation analysis, 72% of the variance in noise annoyance was explained by the noise exposure (L(den)) and nonacoustical variables. The model provides insights into several causal mechanisms underlying the formation of railway noise annoyance considering indirect and reciprocal effects. The concern about harmful effects of railway noise and railway traffic, the perceived control and coping capacity, and the individual noise sensitivity were the most important factors that influence noise annoyance. All effects of the nonacoustical factors on annoyance were mediated by the perceived control and coping capacity and additionally proposed indirect effects of the theoretical model were supported by the data.

  7. FTIR analysis of food poisons

    Science.gov (United States)

    Yasui, Sritana C.

    1992-03-01

    Single and rapid analyses of chemical poisons or contaminants in different food matrices are explored. Various FT-IR accessories are utilized and compared for the detection sensitivity. Detection enhancements by combining with chromatographic techniques are investigated.

  8. An experimental study of the structural and vibrational properties of sesquiterpene lactone cnicin using FT-IR, FT-Raman, UV-visible and NMR spectroscopies

    Science.gov (United States)

    Chain, Fernando; Romano, Elida; Leyton, Patricio; Paipa, Carolina; Catalán, César Atilio Nazareno; Fortuna, Mario Antonio; Brandán, Silvia Antonia

    2014-05-01

    An experimental and theoretical investigation of cnicin is presented, combining the use of infrared, Raman, NMR and UV-visible spectroscopies with density functional theory (DFT) that employs hybrid B3LYP exchange correlation functional and a 6-31G∗ basis set. The molecular electrostatic potentials, atomic charges, bond orders, stabilization energies, topological properties and energy gap are presented by performing NBO, AIM and HOMO-LUMO calculations at the same level of theory as cnicin. A complete vibrational compound assignment was performed by employing internal coordinate analysis and a scaled quantum mechanical force field (SQMFF) methodology. Comparisons between the theoretical and experimental vibrational and ultraviolet-visible spectra show a strong concordance. The geometrical parameters and NBO studies suggest a probable negative Cotton effect for cnicin, which can be attributed to the π → π∗ transition for an α,β-unsaturated γ-lactone, as reported in the literature.

  9. Quantitative structure-activity relationship modeling of polycyclic aromatic hydrocarbon mutagenicity by classification methods based on holistic theoretical molecular descriptors.

    Science.gov (United States)

    Gramatica, Paola; Papa, Ester; Marrocchi, Assunta; Minuti, Lucio; Taticchi, Aldo

    2007-03-01

    Various polycyclic aromatic hydrocarbons (PAHs), ubiquitous environmental pollutants, are recognized mutagens and carcinogens. A homogeneous set of mutagenicity data (TA98 and TA100,+S9) for 32 benzocyclopentaphenanthrenes/chrysenes was modeled by the quantitative structure-activity relationship classification methods k-nearest neighbor and classification and regression tree, using theoretical holistic molecular descriptors. Genetic algorithm provided the selection of the best subset of variables for modeling mutagenicity. The models were validated by leave-one-out and leave-50%-out approaches and have good performance, with sensitivity and specificity ranges of 90-100%. Mutagenicity assessment for these PAHs requires only a few theoretical descriptors of their molecular structure.

  10. Effect of the Al Siting on the Structure of Co(II) and Cu(II) Cationic Sites in Ferrierite. A Periodic DFT Molecular Dynamics and FTIR Study

    Czech Academy of Sciences Publication Activity Database

    Sklenák, Štěpán; Andrikopoulos, Prokopis C.; Whittleton, Sarah R.; Jirglová, Hana; Sazama, Petr; Benco, L.; Bucko, T.; Hafner, J.; Sobalík, Zdeněk

    2013-01-01

    Roč. 117, č. 8 (2013), s. 3958-3968 ISSN 1932-7447 R&D Projects: GA AV ČR IAA400400812; GA ČR GA203/09/1627 Institutional support: RVO:61388955 Keywords : SELECTIVE CATALYTIC-REDUCTION * HIGH-RESOLUTION AL-27 * DENSITY -FUNCTIONAL THEORY Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.835, year: 2013

  11. Study of melanoma invasion by FTIR spectroscopy

    Science.gov (United States)

    Yang, Y.; Sulé-Suso, J.; Sockalingum, G. D.

    2008-02-01

    Compared to other forms of skin cancer, a malignant melanoma has a high risk of spreading to other parts of the body. Melanoma invasion is a complex process involving changes in cell-extracellular matrix (ECM) interaction and cell-cell interactions. To fully understand the factors which control the invasion process, a human skin model system was reconstructed. HBL (a commercially available cell line) melanoma cells were seeded on a skin model with and without the presence of keratinocytes and/or fibroblasts. After 14 days culture, the skin specimens were fixed, parafin embedded and cut into 7 µm sections. The de-parafinised sections were investigated by synchrotron Fourier transformed infrared (FTIR) microspectroscopy to study skin cell invasion behaviour. The advantage of using FTIR is its ability to obtain the fingerprint information of the invading cells in terms of protein secondary structure in comparison to non-invading cells and the concentration of the enzyme (matrix-metalloproteinase) which digests protein matrix, near the invading cells. With aid of the spectral mapping images, it is possible to pinpoint the cells in non-invasion and invasion area and analyse the respective spectra. It has been observed that the protein bands in cells and matrix shifted between non-invasive and invasive cells in the reconstructed skin model. We hypothesise that by careful analysis of the FTIR data and validation by other models, FTIR studies can reveal information on which type of cells and proteins are involved in melanoma invasion. Thus, it is possible to trace the cell invasion path by mapping the spectra along the interface of cell layer and matrix body by FTIR spectroscopy.

  12. THEORETICAL ASPECTS, EXPERIMENTAL INVESTIGATIONS AND EFFICIENCY IN USAGE OF HIGH-STRENGTH CONCRETE FOR BRIDGE STRUCTURES

    Directory of Open Access Journals (Sweden)

    G. D. Liakhevich

    2014-01-01

    Full Text Available In Belarus concrete with strength up to 60 MPA is used for construction. At the same time high strength concrete with compressive strength above 60 MPA is widely used in all industrially developed countries. High- strength concrete is included in regulatory documents of the European Union and that fact has laid a solid foundation for its application. High strength concrete is produced using highly dispersed silica additives, such as micro-silica and plasticizers (super-plasticizers with a water/cement (w/c ratio not greater than 0.4.Theoretical aspects of high-strength concrete for bridge structures have been studied in the paper. The paper shows a positive impact of highly dispersed additives on structure and physico-mechanical properties of cement compositions, namely: reduction of total porosity of a cement stone in concrete while increasing volumetric concentration and dispersion of a filler; binding of calcium hydroxide with the help of amorphised micro-silica; increased activity of mineral additives during their thin shredding; acceleration of the initial stage of chemical hardening of cement compositions with highly dispersed particle additives that serve as centers of crystallization; “binder-additive” cluster formation due to high surface energy of highly dispersed additive particles; hardening of surface area between a cement stone and aggregates in concrete; high-strength concretes are gaining strength much faster than conventional concretes.Technology of preparation and composition of high-strength concrete using highly dispersed mineral additives and super-plasticizer has been developed in the paper. This concrete will ensure a higher density, wa- ter-and gas tightness, increased resistance to aggressive environment, reduced consumption of concrete and reinforcement, reduced transport and installation weight, increased initial strength, early easing of shutters and preliminary compression, increased length of bridge spans

  13. Shining light on the differences in molecular structural chemical makeup and the cause of distinct degradation behavior between malting- and feed-type barley using synchrotron FTIR microspectroscopy: a novel approach.

    Science.gov (United States)

    Yu, Peiqiang; Doiron, Kevin; Liu, Dasen

    2008-05-14

    The objective of this study was to use advanced synchrotron-sourced FTIR microspectroscopy (SFTIRM) as a novel approach to identify the differences in protein and carbohydrate molecular structure (chemical makeup) between these two varieties of barley and illustrate the exact causes for their significantly different degradation kinetics. Items assessed included (1) molecular structural differences in protein amide I to amide II intensities and their ratio within cellular dimensions, (2) molecular structural differences in protein secondary structure profile and their ratios, and (3) molecular structural differences in carbohydrate component peak profile. Our hypothesis was that molecular structure (chemical makeup) affects barley quality, fermentation, and degradation behavior in both humans and animals. Using SFTIRM, the protein and carbohydrate molecular structural chemical makeup of barley was revealed and identified. The protein molecular structural chemical makeup differed significantly between the two varieties of barleys. No difference in carbohydrate molecular structural chemical makeup was detected. Harrington was lower than Valier in protein amide I, amide II, and protein amide I to amide II ratio, while Harrington was relatively higher in model-fitted protein alpha-helix and beta-sheet, but lower in the others (beta-turn and random coil). These results indicated that it is the molecular structure of protein (chemical makeup) that may play a major role in the different degradation kinetics between the two varieties of barleys (not the molecular structure of carbohydrate). It is believed that use of the advanced synchrotron technology will make a significant step and an important contribution to research in examining the molecular structure (chemical makeup) of plant, feed, and seeds.

  14. Shining Light on the Differences in Molecular Structural Chemical Makeup and the Cause of Distinct Degradation Behavior Between Malting- and Feed- Type Barley Using Synchrotorn FTIR Microspectroscopy: A Novel Approach

    International Nuclear Information System (INIS)

    Yu, P.; Doiron, K.; Liu, D.

    2008-01-01

    The objective of this study was to use advanced synchrotron-sourced FTIR microspectroscopy (SFTIRM) as a novel approach to identify the differences in protein and carbohydrate molecular structure (chemical makeup) between these two varieties of barley and illustrate the exact causes for their significantly different degradation kinetics. Items assessed included (1) molecular structural differences in protein amide I to amide II intensities and their ratio within cellular dimensions, (2) molecular structural differences in protein secondary structure profile and their ratios, and (3) molecular structural differences in carbohydrate component peak profile. Our hypothesis was that molecular structure (chemical makeup) affects barley quality, fermentation, and degradation behavior in both humans and animals. Using SFTIRM, the protein and carbohydrate molecular structural chemical makeup of barley was revealed and identified. The protein molecular structural chemical makeup differed significantly between the two varieties of barleys. No difference in carbohydrate molecular structural chemical makeup was detected. Harrington was lower than Valier in protein amide I, amide II, and protein amide I to amide II ratio, while Harrington was relatively higher in model-fitted protein a-helix and β-sheet, but lower in the others (β-turn and random coil). These results indicated that it is the molecular structure of protein (chemical makeup) that may play a major role in the different degradation kinetics between the two varieties of barleys (not the molecular structure of carbohydrate). It is believed that use of the advanced synchrotron technology will make a significant step and an important contribution to research in examining the molecular structure (chemical makeup) of plant, feed, and seeds.

  15. Study of Barley Grain Molecular Structure for Ruminants Using DRIFT, FTIR-ATR and Synchrotron Radiation Infrared Microspectroscopy (SR-IMS): A Review

    Science.gov (United States)

    Yu, Peiqiang

    2012-05-01

    Barley inherent structures are highly associated with nutrient utilization and availability in both humans and animals. Barley has different degradation kinetics compared with other cereal grains. It has a relatively higher degradation rate and extent, which often cause digestive disorder in the rumen. Therefore understanding barley inherent structure at cellular and molecular levels and processing-induced structure changes is important, because we can manipulate barley inherent structures and digestive behaviors. Several molecular spectroscopy techniques can be used to detect barley inherent structures at cellular and molecular levels. This article reviews several applications of the IR molecular spectral bioanalytical techniques - DRIFT, FT/IR-ATR and SR-IMS for barley chemistry, molecular structure and molecular nutrition research

  16. Synthesis, structural, spectral (FTIR, FT-Raman, UV, NMR), NBO and first order hyperpolarizability analysis of N-phenylbenzenesulfonamide by density functional theory.

    Science.gov (United States)

    Govindarasu, K; Kavitha, E; Sundaraganesan, N

    2014-12-10

    In this study sulfonamide compound, N-phenylbenzenesulfonamide (NPBS) has been synthesized and grown as a high quality single crystal by the slow evaporation solution growth technique. The grown crystals were characterized by the Fourier transform infrared (4000-400cm(-1)), Fourier transform Raman (3500-500cm(-1)), UV-Vis (200-800nm) and NMR spectroscopy. Density functional (DFT) calculations have been carried out for the compound NPBS by utilizing DFT level of theory using B3LYP/6-31G(d,p) as basis set. The theoretical vibrational frequencies and optimized geometric parameters such as bond lengths and bond angles have been calculated by using quantum chemical methods. The stability of the molecule arising from hyper conjugative interaction and charge delocalization has been analyzed using NBO analysis. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The chemical reactivity and ionization potential of NPBS were also calculated. In addition, Molecular Electrostatic Potential (MEP), Frontier Molecular Orbital (FMO) analysis was investigated using theoretical calculations. The thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied. Finally, geometric parameters, vibrational bands were compared with available experimental data of the molecules. Published by Elsevier B.V.

  17. Theoretical analysis of a new, efficient microfluidic magnetic bead separator based on magnetic structures on multiple length scales

    DEFF Research Database (Denmark)

    Smistrup, Kristian; Bu, Minqiang; Wolff, Anders

    2008-01-01

    We present a theoretical analysis of a new design for microfluidic magnetic bead separation. It combines an external array of mm-sized permanent magnets with magnetization directions alternating between up and down with mu m-sized soft magnetic structures integrated in the bottom of the separatio...

  18. Theoretical study of structure, pKa, lipophilicity, solubility, absorption, and polar surface area of some centrally acting antihypertensives

    NARCIS (Netherlands)

    Dr. Remko, M.; Swart, M.; Bickelhaupt, F.M.

    2006-01-01

    The methods of theoretical chemistry have been used to elucidate the molecular properties of the substituted imidazoline and oxazoline structures, a class of potent agonists and antagonists of imidazoline receptors. The geometries of various tautomers and isomers of 2-[2,6-dichlorophenylimino

  19. Molecular Chemical Structure of Barley Proteins Revealed by Ultra-Spatially Resolved Synchrotron Light Sourced FTIR Microspectroscopy: Comparison of Barley Varieties

    International Nuclear Information System (INIS)

    Yu, P.

    2007-01-01

    Barley protein structure affects the barley quality, fermentation, and degradation behavior in both humans and animals among other factors such as protein matrix. Publications show various biological differences among barley varieties such as Valier and Harrington, which have significantly different degradation behaviors. The objectives of this study were to reveal the molecular structure of barley protein, comparing various varieties (Dolly, Valier, Harrington, LP955, AC Metcalfe, and Sisler), and quantify protein structure profiles using Gaussian and Lorentzian methods of multi-component peak modeling by using the ultra-spatially resolved synchrotron light sourced Fourier transform infrared microspectroscopy (SFTIRM). The items of the protein molecular structure revealed included protein structure α-helices, β-sheets, and others such as β-turns and random coils. The experiment was performed at the National Synchrotron Light Source in Brookhaven National Laboratory (BNL, US Department of Energy, NY). The results showed that with the SFTIRM, the molecular structure of barley protein could be revealed. Barley protein structures exhibited significant differences among the varieties in terms of proportion and ratio of model-fitted α-helices, β-sheets, and others. By using multi-component peaks modeling at protein amide I region of 1710-1576 cm -1 , the results show that barley protein consisted of approximately 18-34% of α-helices, 14-25% of β-sheets, and 44-69% others. AC Metcalfe, Sisler, and LP955 consisted of higher (P 0.05). The ratio of α-helices to others (0.3 to 1.0, P < 0.05) and that of β-sheets to others (0.2 to 0.8, P < 0.05) were different among the barley varieties. It needs to be pointed out that using a multi-peak modeling for protein structure analysis is only for making relative estimates and not exact determinations and only for the comparison purpose between varieties. The principal component analysis showed that protein amide I Fourier

  20. An improved synthesis, spectroscopic (FT-IR, NMR) study and DFT computational analysis (IR, NMR, UV-Vis, MEP diagrams, NBO, NLO, FMO) of the 1,5-methanoazocino[4,3-b]indole core structure

    Science.gov (United States)

    Uludağ, Nesimi; Serdaroğlu, Goncagül

    2018-03-01

    This study examines the synthesis of azocino[4,3-b]indole structure, which constitutes the tetracyclic framework of uleine, dasycarpidoneand tubifolidineas well as ABDE substructure of the strychnosalkaloid family. It has been synthesized by Fischer indolization of 2 and through the cylization of 4 by 2,3-dichlor-5-6-dicyanobenzoquinone (DDQ). 1H and 1C NMR chemical shifts have been predicted with GIAO approach and the calculated chemical shifts show very good agreement with observed shifts. FT-IR spectroscopy is important for the analysis of functional groups of synthesized compounds and we also supported FT-IR vibrational analysis with computational IR analysis. The vibrational spectral analysis was performed at B3LYP level of the theory in both the gas and the water phases and it was compared with the observed IR values for the important functional groups. The DFT calculations have been conducted to determine the most stable structure of the 1,2,3,4,5,6,7-Hexahydro-1,5-methanoazocino [4,3-b] indole (5). The Frontier Molecular Orbital Analysis, quantum chemical parameters, physicochemical properties have been predicted by using the same theory of level in both gas phase and the water phase, at 631 + g** and 6311++g** basis sets. TD- DFT calculations have been performed to predict the UV- Vis spectral analysis for this synthesized molecule. The Natural Bond Orbital (NBO) analysis have been performed at B3LYP level of theory to elucidate the intra-molecular interactions such as electron delocalization and conjugative interactions. NLO calculations were conducted to obtain the electric dipole moment and polarizability of the title compound.

  1. Advances in theoretical and experimental XAFS studies of thermodynamic properties, anharmonic effects and structural determination of fcc crystals

    Science.gov (United States)

    Hung, Nguyen Van; Thang, Cu Sy; Duc, Nguyen Ba; Vuong, Dinh Quoc; Tien, Tong Sy

    2017-12-01

    Thermodynamic properties, anharmonic effects and structural determination of fcc crystals have been studied based on the theoretical and experimental Debye-Waller factors presented in terms of cumulant expansion up to the third order, thermal expansion coefficient, X-ray absorption fine structure (XAFS) spectra and their Fourier transform magnitudes. The advances in these studies are performed by the further development of the anharmonic correlated Einstein model primary only for approximating three first XAFS cumulants into the method using that all the considered theoretical and experimental XAFS parameters have been provided based on only the calculated and measured second cumulants. The obtained cumulants describe the anharmonic effects in XAFS contributing to the accurate structural determination. Numerical results for Cu are found to be in good agreement with the experimental values extracted by using the present advanced method and with those obtained by the other measurements.

  2. Theoretical modeling and design of photonic structures in zeolite nanocomposites for gas sensing. Part I: surface relief gratings.

    Science.gov (United States)

    Cody, D; Naydenova, I

    2017-12-01

    The suitability of holographic structures fabricated in zeolite nanoparticle-polymer composite materials for gas sensing applications has been investigated. Theoretical modeling of the sensor response (i.e., change in hologram readout due to a change in refractive index modulation or thickness as a result of gas adsorption) of different sensor designs was carried out using Raman-Nath theory and Kogelnik's coupled wave theory. The influence of a range of parameters on the sensor response of holographically recorded surface and volume photonic grating structures has been studied, namely the phase difference between the diffracted and probe beam introduced by the grating, grating geometry, thickness, spatial frequency, reconstruction wavelength, and zeolite nanoparticle refractive index. From this, the optimum fabrication conditions for both surface and volume holographic gas sensor designs have been identified. Here, in part I, results from theoretical modeling of the influence of design on the sensor response of holographically inscribed surface relief structures for gas sensing applications is reported.

  3. Theoretical investigation of the structural stabilities, optoelectronic properties and thermodynamic characteristics of GaPxSb1-x ternary alloys

    Science.gov (United States)

    Oumelaz, F.; Nemiri, O.; Boumaza, A.; Ghemid, S.; Meradji, H.; Bin Omran, S.; El Haj Hassan, F.; Rai, D. P.; Khenata, R.

    2017-12-01

    In this theoretical study, we have investigated the structural, phase transition, electronic, thermodynamic and optical properties of GaPxSb1-x ternary alloys. Our calculations are performed with the WIEN2k code based on density functional theory using the full-potential linearized augmented plane wave method. For the electron exchange-correlation potential, a generalized gradient approximation within Wu-Cohen scheme is considered. The recently developed Tran-Blaha modified Becke-Johnson potential has also been used to improve the underestimated band gap. The structural properties, including the lattice constants, the bulk moduli and their pressure derivatives are in very good agreement with the available experimental data and theoretical results. Several structural phase transitions were studied here to establish the stable structure and to predict the phase transition under hydrostatic pressure. The computed transition pressure (Pt) of the material of our interest from the zinc blende (B3) to the rock salt (B1) phase has been determined and found to agree well with the experimental and theoretical data. The calculated band structure shows that GaSb binary compound and the ternary alloys are direct band gap semiconductors. Optical parameters such as the dielectric constants and the refractive indices are calculated and analyzed. The thermodynamic results are also interpreted and analyzed.

  4. Theoretical investigations of the structures and electronic spectra of 8-hydroxylquinoline derivatives

    Science.gov (United States)

    Ning, Pan; Ren, Tiegang; Zhang, Yanxin; Zhang, Jinglai

    2013-11-01

    The spectroscopic properties of 8-hydroxyquinoline derivatives are theoretically investigated by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The target molecules are divided into two groups: group (I): (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (A), together with corresponding potential reaction products of A with acetic acid, i.e., (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (AR1), and (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (AR2); group (II): (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (B), as well as potential reaction products of B with acetic acid, i.e., (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (BR1), and (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (BR2). The geometries are optimized by B3LYP and M06 methods. The results indicate that product molecules tend to be effectively planar compared with reactants. Subsequently, UV absorption spectra are simulated through TD-DFT method with PCM model to further confirm the reasonable products of two reactions. AR2 and BR2 are identified as the target molecules through the experimental spectra for the real products. It is worth noting that the maximum absorption wavelengths of compounds AR2 and BR2 present prominent red shift compared the initial reactants A and B, respectively, which should be ascribed to the enhancive planarity of products that mentioned above and the decreased HOMO-LUMO energy gap. Geometric structures and optical properties for corresponding compounds are discussed in detail.

  5. A combined experimental and theoretical approach for structural, spectroscopic, NLO, NBO, thermal and photophysical studies of new fluorescent 5-amino-1-(7-chloroquinolin-4-yl)-1H-1,2,3-triazole-4-carbonitrile using density functional theory

    Science.gov (United States)

    Singh, Harjinder; Singh, Ashima; Khurana, J. M.

    2017-11-01

    We have synthesized a new fluorescent 5-amino-1-(7-chloroquinolin-4-yl)-1H-1,2,3-triazole-4-carbonitrile containing 1,2,3-triazole moiety. The properties such as optimized structural parameters, spectroscopic (FT-IR and NMR), electronic and photophysical properties were investigated experimentally as well as theoretically using density functional theory calculations. The NMR spectrum was recorded in DMSO and the chemical shifts of hydrogen and carbon atoms were studied experimentally as well as theoretically. Electronic properties of molecule such as electrostatic surface potential analysis, charge analysis, the frontier molecular orbital analysis, total density of states, absorption-emission characteristics of molecule were studied. Nonlinear optical properties, reduced density gradient and natural bond orbital analysis were also studied. The first order hyperpolarizability (β0) was calculated and found to be six times higher than urea which makes it a potential NLO material. This new compound showed absorption spectra at 326-386 nm while emission band in range of 375-403 nm in different solvents. The ground state and excited state dipole moments were determined using solvatochromic methods and compared with theoretically calculated values. The interaction of synthesized compound with different solvents was also investigated using Kamlet-Taft and Catalan methods. The chemical reactivity indices and thermodynamic properties were also evaluated.

  6. FTIR spectroscopy of flavin-binding photoreceptors.

    Science.gov (United States)

    Yamada, Daichi; Kandori, Hideki

    2014-01-01

    Light-induced difference Fourier transform infrared (FTIR) spectroscopy is a powerful, sensitive, and informative method to study structure-function relationships in photoreceptive proteins. Strong absorption of water in the IR region is always problematic in this method, but if water content in the sample is controlled during measurements, this method can provide useful information on a single protein-bound water molecule. We established three kinds of sample preparations: hydrated film, redissolved sample, and concentrated solution. Hydrated films were used for the measurements of LOV and BLUF domains, where accurate difference FTIR spectra were obtained in the whole mid-IR region (4,000-800 cm(-1)). Vibrations of S-H stretch of cysteine, O-H stretch of water, and O-H stretch of tyrosine provide important information on hydrogen bonds in these proteins. Redissolved samples were used for the measurements of (6-4) photolyase, in which enzymatic turnover takes place. From the illumination time-dependence of excess amount of substrate, it is possible to isolate the signal originating from the binding of enzyme to substrate. If proteins are less tolerant to drying, as for example cryptochromes of the DASH type, concentrated solution is used. Detailed methodological aspects in light-induced difference FTIR spectroscopy are reviewed by mainly focusing on our results.

  7. Effect of Fe(II)/Ce(III) dosage ratio on the structure and anion adsorptive removal of hydrothermally precipitated composites: Insights from EXAFS/XANES, XRD and FTIR

    KAUST Repository

    Chubar, Natalia

    2016-10-24

    In this work, we present material chemistry in the hydrothermal synthesis of new complex structure materials based on various dosage ratios of Fe and Ce (1:0, 2:1, 1:1, 1:2, 0:1), characterize them by the relevant methods that allow characterization of both crystalline and amorphous phases and correlate their structure/surface properties with the adsorptive performance of the five toxic anions. The applied synthesis conditions resulted in the formation of different compounds of Fe and Ce components. The Fe-component was dominated by various phases of Fe hydrous oxides, whereas the Ce-component was composed of various phases of Ce carbonates. The presence of two metal salts in raw materials resulted in the formation of a mesoporous structure and averaged the surface area compared to one metal-based material. The surface of all Fe-Ce composites was abundant in Fe component phases. Two-metal systems showed stronger anion removal performance than one-metal materials. The best adsorption was demonstrated by Fe-Ce based materials that had low crystallinity, that were rich in phases and that exhibited surfaces were abundant in greater number of surface functional groups. Notably, Fe extended fine structures simulated by EXAFS in these better adsorbents were rich from oscillations from both heavy and light atoms. This work provides new insights on the structure of composite inorganic materials useful to develop their applications in adsorption and catalysis. It also presents new inorganic anion exchangers with very high removal potential to fluoride and arsenate.

  8. Determination of pKa and the corresponding structures of quinclorac using combined experimental and theoretical approaches

    Science.gov (United States)

    Song, Dean; Sun, Huiqing; Jiang, Xiaohua; Kong, Fanyu; Qiang, Zhimin; Zhang, Aiqian; Liu, Huijuan; Qu, Jiuhui

    2018-01-01

    As an emerging environmental contaminant, the herbicide quinclorac has attracted much attention in recent years. However, a very fundamental issue, the acid dissociation of quinclorac has not yet to be studied in detail. Herein, the pKa value and the corresponding structures of quinclorac were systematically investigated using combined experimental and theoretical approaches. The experimental pKa of quinclorac was determined by the spectrophotometric method to be 2.65 at 25 °C with ionic strength of 0.05 M, and was corrected to be 2.56 at ionic strength of zero. The molecular structures of quinclorac were then located by employing the DFT calculation. The anionic quinclorac was directly located with the carboxylic group perpendicular to the aromatic ring, while neutral quinclorac was found to be the equivalent twin structures. The result was further confirmed by analyzing the UV/Vis and MS-MS2 spectra from both experimental and theoretical viewpoints. By employing the QSPR approach, the theoretical pKa of QCR was determined to be 2.50, which is excellent agreement with the experimental result obtained herein. The protonation of QCR at the carboxylic group instead of the quinoline structure was attributed to the weak electronegative property of nitrogen atom induced by the electron-withdrawing groups. It is anticipated that this work could not only help in gaining a deep insight into the acid dissociation of quinclorac but also offering the key information on its reaction and interaction with others.

  9. Theoretical modeling of a new structure of III-V tandem solar cells by ...

    African Journals Online (AJOL)

    junction solar cell is theoretically investigated by optimizing the thickness of GaAs and GaInPandusing a new optical model to separate the junction between the two solar cell in order to solve problems of tunnel junction and difficulties of fabrication.

  10. Structural flexibility of 2-hetaryl chromium aminocarbene complexes: Experimental and theoretical evidence

    Czech Academy of Sciences Publication Activity Database

    Kvapilová, Hana; Eigner, V.; Hoskovcová, I.; Tobrman, T.; Čejka, J.; Záliš, Stanislav

    2014-01-01

    Roč. 421, SEP 2014 (2014), s. 439-445 ISSN 0020-1693 R&D Projects: GA MŠk LD14129 Institutional support: RVO:61388955 Keywords : Transition metal complex * Density functional theory * Potential energy surface Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.046, year: 2014

  11. Theoretical studies of the g factors and local structure for Pt 3 in -Al ...

    Indian Academy of Sciences (India)

    3 are theoretically investigated from the perturbation formulas of the factors for a 57 ion in trigonal symmetry. The Pt3+ impurity is found to experience an outward displacement by about 0.18 Å away from the centre of the oxygen ...

  12. The application of Fourier-transform infrared (FTIR) and Raman spectroscopy (FTR) to the evaluation of structural changes in wool fibre keratin after deuterium exchange and modification by the orthosilicic acid

    Science.gov (United States)

    Wojciechowska, Elżbieta; Włochowicz, Andrzej; Wysocki, Marian; Pielesz, Anna; Wesełucha-Birczyńska, Aleksandra

    2002-09-01

    An injury of hair macrostructure and substantial alkalinity of the water-lipid shield medium on wool fibre surface is conducive to a transition of heavy metal elements into ion forms. It also helps SiO 2 in a transition into a colloidal form of orthosilicic acid and its penetration in this form of the wool fibre structure. Consequently, it leads to the biomineralization of the wool fibre [J. Mol. Struct. 511-512 (1999) 307; J. Mol. Struct. 511-512 (2000) 397]. Changes taking place in the process of biomineralization, mainly in the amorphous region, may be responsible for the effectiveness of the technological processes and the properties of ready wool products [3]. Wool fibres obtained from Polish Merino sheep were treated with solution of orthosilicic acid (H 4SiO 4· nH 2O) in experimental conditions during which fibres first underwent extraction with methylene chloride and them with asolution of orthosilicic acid in alkaline medium. Studies of deuterium exchange in the wool fibre keratin were applied to study changes in the structure of wool fibre keratin in the process of orthosilicic acid treatment. The changes in the structure of wool fibre were studied by means of infrared spectroscopy (FTIR) and Raman spectroscopy (FTR).

  13. PREFACE: 10th Summer School on Theoretical Physics 'Symmetry and Structural Properties of Condensed Matter'

    Science.gov (United States)

    Lulek, Tadeusz; Wal, Andrzej; Lulek, Barbara

    2010-03-01

    This volume contains the Proceedings of the Tenth Summer School on Theoretical Physics under the banner title 'Symmetry and Structural Properties of Condensed Matter' (SSPCM 2009). The School was organized by Rzeszow University of Technology, Poland, in cooperation with AGH University of Science and Technology, Cracow, Poland, and took place on 2-9 September 2009 in Myczkowce, Poland. With this meeting we have reached the round number ten of the series of biannual SSPCM schools, which started in 1990 and were focused on some advanced mathematical methods of condensed matter physics. The first five meetings were held in Zajaczkowo near Poznan, under the auspices of The Institute of Physics of Adam Mickiewicz University, and the last five in Myczkowce near Rzeszów, in the south-eastern part of Poland. Within these two decades several young workers who started at kindergarten lectures at SSPCM, have now reached their PhD degrees, professorships and authority. Proceedings of the first seven SSPCM meetings were published as separate volumes by World Scientific, and the last two as volumes 30 and 104 of Journal of Physics: Conference Series. The present meeting is also the third of the last schools which put the emphasis on quantum informatics. The main topics of our jubilee SSPCM'09 are the following: Information processing, entanglement, and tensor calculus, Integrable models and unitary symmetry, Finite systems and nanophysics. The Proceedings are divided into three parts accordingly. The school gathered together 55 participants from seven countries and several scientific centers in Poland, accommodating again advanced research with young collaborators and students. Acknowledgements The Organizing Committee would like to express its gratitude to all participants for their many activities during the School and for creating a friendly and inspiring atmosphere within our SSPCM society. Special thanks are due to all lecturers for preparing and presenting their talks and

  14. Synthesis, crystal structure, vibrational spectroscopy, optical properties and theoretical studies of a new organic-inorganic hybrid material: [((CH3)2NH2)(+)]6·[(BiBr6)(3-)]2.

    Science.gov (United States)

    Ben Ahmed, A; Feki, H; Abid, Y

    2014-12-10

    A new organic-inorganic hybrid material, [((CH3)2NH2)(+)]6·[(BiBr6)(3-)]2, has been synthesized and characterized by X-ray diffraction, FT-IR, Raman spectroscopy and UV-Visible absorption. The studied compound crystallizes in the triclinic system, space group P1¯ with the following parameters: a=8.4749(6)(Å), b=17.1392(12)(Å), c=17.1392(12)(Å), α=117.339(0)°, β=99.487(0)°, γ=99.487(0)° and Z=2. The crystal lattice is composed of a two discrete (BiBr6)(3-) anions surrounded by six ((CH3)2NH2)(+) cations. Complex hydrogen bonding interactions between (BiBr6)(3-) and organic cations from a three-dimensional network. Theoretical calculations were performed using density functional theory (DFT) for studying the molecular structure, vibrational spectra and optical properties of the investigated molecule in the ground state. The full geometry optimization of designed system is performed using DFT method at B3LYP/LanL2DZ level of theory using the Gaussian03. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from FT-IR and Raman spectra are assigned based on the results of the theoretical calculations. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental UV-Visible spectrum. The results show good consistent with the experiment and confirm the contribution of metal orbital to the HOMO-LUMO boundary. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Molecular structure (monomeric and dimeric) and hydrogen bonds in 5-benzyl 2-thiohydantoin studied by FT-IR and FT-Raman spectroscopy and DFT calculations.

    Science.gov (United States)

    Deval, Vipin; Kumar, Amit; Gupta, Vineet; Sharma, Anamika; Gupta, Archana; Tandon, Poonam; Kunimoto, Ko-Ki

    2014-11-11

    In the present work the structural and spectral characteristics of 5-benzyl-2-thiohydantoin (5-BTH) have been studied by methods of infrared, Raman spectroscopy and quantum chemistry. Electrostatic potential surface, optimized geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by density functional theory (DFT) employing B3LYP with complete relaxation in the potential energy surface using 6-311G++(d,p) basis set. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. UV-vis spectrum of the compound was recorded in methanol solvent. The TD-DFT calculations have been performed to explore the influence of electronic absorption spectra in the gas phase, as well as in solution environment using PCM and 6-311++G(d,p) basis set. In addition, the thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Synthesis, structure, spectral properties and theoretical studies of two half-sandwich titanium-complexes with adamantoxy ligands

    Czech Academy of Sciences Publication Activity Database

    Varga, Vojtěch; Mach, Karel; Pinkas, Jiří; Kubišta, Jiří; Szarka, K.; Gyepes, R.

    2017-01-01

    Roč. 1142, AUG 2017 (2017), s. 248-254 ISSN 0022-2860 R&D Projects: GA ČR(CZ) GAP207/12/2368; GA ČR(CZ) GA14-08531S Institutional support: RVO:61388955 Keywords : half- sandwich complex * ionic complex * solid-state structure Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 1.753, year: 2016

  17. Synthesis, structure, spectral properties and theoretical studies of two half-sandwich titanium-complexes with adamantoxy ligands

    Czech Academy of Sciences Publication Activity Database

    Varga, Vojtěch; Mach, Karel; Pinkas, Jiří; Kubišta, Jiří; Szarka, K.; Gyepes, R.

    2017-01-01

    Roč. 1142, AUG 2017 (2017), s. 248-254 ISSN 0022-2860 R&D Projects: GA ČR(CZ) GAP207/12/2368; GA ČR(CZ) GA14-08531S Institutional support: RVO:61388955 Keywords : half-sandwich complex * ionic complex * solid-state structure Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 1.753, year: 2016

  18. Theoretical studies of the g factors and local structure for Pt in α-Al2O3

    Indian Academy of Sciences (India)

    Theoretical studies of the g factors and local structure for Pt. 3+ in α-Al2O3. Z H ZHANG1, SYWU1,2,∗. , S X ZHANG1 and L L LI1. 1Department of Applied Physics, University of Electronic Science and Technology of China,. Chengdu 610054, People's Republic of China. 2International Centre for Materials Physics, Chinese ...

  19. Core value and theoretical logic of structure-borne noise.Part 1: summary, value and cognitive subversion

    Directory of Open Access Journals (Sweden)

    WU Chongjian

    2018-02-01

    Full Text Available During the quieting process, a submarine faces the new energy differences of radiated noise. The theory of structure-borne noise must be deeply analyzed and applied as it is one of the most indispensably important theories for Chinese submarines to achieve transcendence. However, if hope is still pinned on improved raft vibration isolation, greater structural rigidity, higher damping or refined construction, the probability of success is almost nil. Researchers must adopt new thinking about structure-borne noise in order to decode the inherent acoustic passwords of structures and reconstruct the complementation characteristics, overlay characteristics and functional design of complex and huge submarine systems, thereby controlling energy input, internal wave conduction and acoustic radiation. As a theoretical tool for solving the "last kilometer" of submarine quietness, this is the core value of structure-borne noise with logically subversive significance.

  20. Halide salts and their structural properties in presence of secondary amine based molecule: A combined experimental and theoretical analysis

    Science.gov (United States)

    Ghosh, Pritam; Hazra, Abhijit; Ghosh, Meenakshi; Chandra Murmu, Naresh; Banerjee, Priyabrata

    2018-04-01

    Biologically relevant halide salts and its solution state structural properties are always been significant. In general, exposure of halide salts into polar solution medium results in solvation which in turn separates the cationic and anionic part of the salt. However, the conventional behaviour of salts might alter in presence of any secondary amine based compound, i.e.; moderately strong Lewis acid. In its consequence, to investigate the effect of secondary amine based compound in the salt solution, novel (E)-2-(4-bromobenzylidene)-1-(perfluorophenyl) hydrazine has been synthesized and used as secondary amine source. The secondary amine compound interestingly shows a drastic color change upon exposure to fluoride salts owing to hydrogen bonding interaction. Several experimental methods, e.g.; SCXRD, UV-Vis, FT-IR, ESI-MS and DLS together with modern DFT (i.e.; DFT-D3) have been performed to explore the structural properties of the halide salts upon exposure to secondary amine based compound. The effect of counter cation of the fluoride salt in binding with secondary amine source has also been investigated.

  1. Theoretical foundations of the so-called cross-reference structures

    DEFF Research Database (Denmark)

    Tarp, Sven

    1999-01-01

    A discussion of the concept of "structure" related to the concept of "cross-reference". On the basis of the distribution structures a completely new way of viewing the lexicographical cross-references of all sorts is presented.......A discussion of the concept of "structure" related to the concept of "cross-reference". On the basis of the distribution structures a completely new way of viewing the lexicographical cross-references of all sorts is presented....

  2. A study of Ganoderma lucidum spores by FTIR microspectroscopy

    Science.gov (United States)

    Wang, Xin; Chen, Xianliang; Qi, Zeming; Liu, Xingcun; Li, Weizu; Wang, Shengyi

    2012-06-01

    In order to obtain unique information of Ganoderma lucidum spores, FTIR microspectroscopy was used to study G. lucidum spores from Anhui Province (A), Liaoning Province (B) and Shangdong Province (C) of China. IR micro-spectra were acquired with high-resolution and well-reproducibility. The IR spectra of G. lucidum spores from different areas were similar and mainly made up of the absorption bands of polysaccharide, sterols, proteins, fatty acids, etc. The results of curve fitting indicated the protein secondary structures were dissimilar among the above G. lucidum spores. To identify G. lucidum spores from different areas, the H1078/H1640 value might be a potentially useful factor, furthermore FTIR microspectroscopy could realize this identification efficiently with the help of hierarchical cluster analysis. The result indicates FTIR microspectroscopy is an efficient tool for identification of G. lucidum spores from different areas. The result also suggests FTIR microspectroscopy is a potentially useful tool for the study of TCM.

  3. FT-IR and FT-Raman spectra, molecular structure and first-order molecular hyperpolarizabilities of a potential antihistaminic drug, cyproheptadine HCl

    Science.gov (United States)

    Sagdinc, Seda G.; Erdas, Dilek; Gunduz, Ilknur; Sahinturk, Ayse Erbay

    2015-01-01

    Cyproheptadine hydrochloride (CYP HCl) {4-(5H-dibenzo[a,d]-cyclohepten-5-ylidene)-1-methylpiperidine hydrochloride} is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local-anesthetic properties. The geometry optimization, Mulliken atomic charges and wavenumber and intensity of the vibrational bands of all of the possible modes of CYP HCl have been calculated using ab initio Hartree-Fock (HF) and density functional theory (DFT) employing the B3LYP functional with the 6-311G(d,p) basis set. We have compared the calculated IR and Raman wavenumbers with experimental data. Quantum-chemical calculations of the geometrical structure, energies, and molecular electrostatic potential and NBO analysis of CYP HCl have been performed using the B3LYP/6-311G(d,p) method. The electric dipole moment (μ), static polarizability (α) and the first hyperpolarizability (β) values of the title compound have been computed using HF and DFT methods. The study reveals that the antihistaminic pharmacological property of CYP HCl has a large β value and, hence, may in general have potential applications in the development of non-linear optical materials. The experimental and calculated results for CYP HCl have also been compared with those for mianserin HCl.

  4. Perspectives of experimental and theoretical studies of self-organized dust structures in complex plasmas under microgravity conditions

    International Nuclear Information System (INIS)

    Tsytovich, V N

    2015-01-01

    We review research aimed at understanding the phenomena occurring in a complex plasma under microgravity conditions. Some aspects of the work already performed are considered that have not previously been given sufficient attention but which are potentially crucial for future work. These aspects, in particular, include the observation of compact dust structures that are estimated to be capable of confining all components of a dust plasma in a bounded spatial volume; experimental evidence of the nonlinear screening of dust particles; and experimental evidence of the excitation of collective electric fields. In theoretical terms, novel collective attraction processes between likely charged dust particles are discussed and all schemes of the shadowy attraction between dust particles used earlier, including in attempts to interpret observations, are reviewed and evaluated. Dust structures are considered from the standpoint of the current self-organization theory. It is emphasized that phase transitions between states of self-organized systems differ significantly from those in homogeneous states and that the phase diagrams should be constructed in terms of the parameters of a self-organized structure and cannot be constructed in terms of the temperature and density or similar parameters of homogeneous structures. Using the existing theoretical approaches to modeling self-organized structures in dust plasmas, the parameter distribution of a structure is recalculated for a simpler model that includes the quasineutrality condition and neglects diffusion. These calculations indicate that under microgravity conditions, any self-organized structure can contain a limited number of dust particles and is finite in size. The maximum possible number of particles in a structure determines the characteristic inter-grain distance in dust crystals that can be created under microgravity conditions. Crystallization criteria for the structures are examined and the quasispherical

  5. Revisiting verbs of emission: an update on some relevant theoretical accounts of lexical specification and argument structure of emission verbs

    Directory of Open Access Journals (Sweden)

    Natasa Milivojevic

    2016-06-01

    Full Text Available The paper addresses the question of what semantic properties lexicalized in verbs determine their syntactic behavior in intransitive motion events and in resultative constructions in English and Serbian. Special attention is devoted to English and Serbian verbs of emission (specifically verbs of sound emission and partly also verbs of light, smell and substance emission regarding their potential to surface as main verbs in these constructions and to combine with directional phrases within specific morphosyntactic templates (unaccusatives and unergatives. The presented research promotes a theoretical view according to which the established syntactic patterns can be applied across the whole class of verbs of emission to express a full er range of atypical verb meanings in motion events. Theoretical conclusions of the research are also relevant for a wider theoretical description of motion events and resultatives in a cross - linguistic perspective. The paper puts forth additional implica tions regarding the projectionalist approach to semantic verb classes against the theoretical framework of Beth Levin (1993. Finally, the paper considers the relevant points of structurally realized similarities via relevant constructional templates in En glish and in Serbian, as well as some important points of morphosyntactic divergence between the two languages. The conclusions presented aim at a more comprehensive contrastive language typology based on language “framing” parameters.

  6. EXPERIMENTAL AND THEORETICAL STUDY OF THE STRUCTURAL, MAGNETIC AND ELECTRONIC PROPERTIES OF THE BA2GDSBO6 PEROVSKITE

    Directory of Open Access Journals (Sweden)

    R. Moreno Mendoza

    2017-06-01

    Full Text Available In this work the procedure to the synthesis of Ba2GdSbO6 complex perovskite by the solid-state reaction method is reported. Theoretically a study of the crystalline and electronic structure was performed into the framework of the Density Functional Theory (DFT. The most stable structure is obtained to be a rhombohedral perovskite with a lattice constant a=6,0840 Å.  Due the occurrence of a mean energy gap of 2,84 eV close to the Fermi level for both up and down spin polarizations this material is classifies as insulator.  The effective magnetic moment of material obtained from the calculations was 7,0 mB. The crystalline structure was analyzed through the X-ray diffraction technique and Rietveld refinement of the experimental data. Results are strongly in agreement with those theoretically predicted. Magnetic response was studied from measurements of magnetic susceptibility as a function of temperature. Results reveal the paramagnetic feature of this material in the temperature regime from 50 K up to 300 K. From the fitting with the Curie law the effective magnetic moment was obtained to be 8,1 mB, which is slightly higher that the theoretical value for the Gd3+ isolated cation predicted by the theory of paramagnetism. The energy gap obtained from experiments of diffuse reflectance is relatively in agreement with the theoretical predictions. The dielectric constant as a function of applied frequencies at room temperature was measured. Results reveal a decreasing behavior with a high value of dielectric constant at low applied frequencies

  7. Characterization of MEMS FTIR spectrometer

    Science.gov (United States)

    Khalil, Diaa; Sabry, Yasser; Omran, Haitham; Medhat, Mostafa; Hafez, Amr; Saadany, Bassam

    2011-03-01

    In this work we present the full characterization of an optical MEMS Fourier Transform Infra Red FTIR spectrometer fabricated by Deep Reactive Ion Etching DRIE Technology on Silicon substrate. Both electrical and optical properties of the spectrometer are measured. The presented techniques allows to build an engineering model for the spectrometer and to predict its main specifications taking into account the specificity of the MEMS technology used in the spectrometer fabrication.

  8. Theoretical nuclear reaction and structure studies using hyperons and photons. Final report

    International Nuclear Information System (INIS)

    Cotanch, S.R.

    1998-01-01

    This report details research progress and results obtained during the ten period from June 1, 1988 through May 31, 1998. In compliance with grant requirements the Principal Investigator, Professor Stephen R. Cotanch, has conducted a research program addressing theoretical investigations of reactions involving hyperons and photons. The Principal Investigator has devoted to this program 50% of his time during the academic year and 100% of this time in the summer. Highlights of significant research results are briefly summarized in this report which respectively correspond to the three sub-programs of this project

  9. Electronic structure of Ni2TiAl: Theoretical aspects and Compton scattering measurement

    Science.gov (United States)

    Sahariya, Jagrati; Ahuja, B. L.

    2012-11-01

    In this paper, we report electron momentum density of Ni2TiAl alloy using an in-house 20 Ci 137Cs (661.65 keV) Compton spectrometer. The experimental data have been analyzed in terms of energy bands and density of states computed using linear combination of atomic orbitals (LCAO) method. In the LCAO computations, we have considered local density approximation, generalized gradient approximation and recently developed second order generalized gradient approximation within the frame work of density functional theory. Anisotropies in theoretical Compton profiles along [1 0 0], [1 1 0] and [1 1 1] directions are also explained in terms of energy bands.

  10. Electronic structure of Ni{sub 2}TiAl: Theoretical aspects and Compton scattering measurement

    Energy Technology Data Exchange (ETDEWEB)

    Sahariya, Jagrati [Department of Physics, University College of Science, M.L. Sukhadia University, Durga Nursery Road, Udaipur 313001, Rajasthan (India); Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, University College of Science, M.L. Sukhadia University, Durga Nursery Road, Udaipur 313001, Rajasthan (India)

    2012-11-01

    In this paper, we report electron momentum density of Ni{sub 2}TiAl alloy using an in-house 20 Ci {sup 137}Cs (661.65 keV) Compton spectrometer. The experimental data have been analyzed in terms of energy bands and density of states computed using linear combination of atomic orbitals (LCAO) method. In the LCAO computations, we have considered local density approximation, generalized gradient approximation and recently developed second order generalized gradient approximation within the frame work of density functional theory. Anisotropies in theoretical Compton profiles along [1 0 0], [1 1 0] and [1 1 1] directions are also explained in terms of energy bands.

  11. Synthesis, structural characterization, luminescent properties and theoretical study of three novel lanthanide metal-organic frameworks of Ho(III), Gd(III) and Eu(III) with 2,5-thiophenedicarboxylate anion

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Lippy F. [Instituto de Química, Universidade do Estado do Rio de Janeiro, Rio de Janeiro 20550-013 (Brazil); Correa, Charlane C. [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG, 36036-330 (Brazil); Ribeiro, Sidney J.L.; Santos, Molíria V. dos [Institute of Chemistry, São Paulo State University − UNESP, CP 355 Araraquara-SP 14801-970 Brazil (Brazil); Dutra, José Diogo L.; Freire, Ricardo O. [Pople Computational Chemistry Laboratory, Departamento de Química, Universidade Federal de Sergipe, São Cristóvão-SE 49100-000 (Brazil); Machado, Flávia C., E-mail: flavia.machado@ufjf.edu.br [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG, 36036-330 (Brazil)

    2015-07-15

    In this paper, the synthesis of three new metal-organic frameworks of lanthanides (LnMOFs) ([Ln{sub 2}(2,5-tdc){sub 3}(dmso){sub 2}]·H{sub 2}O){sub n} (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structure of (1) reveals that each lanthanide ion is seven-coordinated by oxygen atoms in an overall distorted capped trigonal – prismatic geometry. The 2,5-tdc{sup 2−} ligands connect four Ln(III) centers, adopting (κ{sup 1}–κ{sup 1})–(κ{sup 1}–κ{sup 1})–μ{sub 4} coordination mode, generating an 8-connected uninodal 3D network. In addition, theoretical studies for Eu(III) complex were performed using the Sparkle model for lanthanide complexes. - Graphical abstract: Three new metal-organic frameworks of lanthanides (LnMOFs) ([Ln{sub 2}(2,5-tdc){sub 3}(dmso){sub 2}]·H{sub 2}O){sub n} (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), were synthesized and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. - Highlights: • Three new LnMOFs were synthesized and fully characterized. • Ho{sup 3+}, Gd{sup 3+} and Eu{sup 3+} complexes photoluminescence properties were investigated. • Theoretical approaches for Eu{sup 3+} complex luminescence has been performed. • An energy level diagram is used to establish the ligand-to-metal energy transfer. • These metal−organic frameworks can act as light conversion molecular devices.

  12. Theoretical calculations of the electronic and vibrational structure of point defects in ionic crystals

    International Nuclear Information System (INIS)

    Wood, R.F.; Wilson, T.M.

    1981-01-01

    The structure of the Hartree-Fock one-electron equations for simple point defects in ionic crystals are discussed. The importance of polarization effects due to the diffuse nature of the wavefunctions in the relaxed excited states are emphasized, and the usefulness of an effective mass approximation indicated. Several approaches to the calculation of the electronic structure are discussed and evaluated. The connection between electronic structure calculations and phonon perturbations are pointed out through a brief discussion of localized perturbation theory

  13. Vibrations and acoustic radiation of thin structures: physical basis, theoretical analysis and numerical methods

    National Research Council Canada - National Science Library

    Filippi, P

    2008-01-01

    ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1.1 General Considerations on Thin Structures . . . . . . . 1.1.2 Overview of the Energy Method . . . . . . . . . . . . . 1.2 Thin Plates...

  14. Theoretical Study on Adhesives Used in Ballistic Protection Structures and Transparent Armor

    Directory of Open Access Journals (Sweden)

    Alil Luminiţa-Cristina

    2015-06-01

    Full Text Available This article is a brief study conducted on adhesives currently used for manufacturing performance ballistic protection structures. The study landmarks several aspects, such as: types of connections available to achieve multilayer structures based on ceramics, metals and polymers; ways in which adhesives influence the ballistic performance of protective structures; analysis of various types of adhesives used in ballistic protection industry; general considerations in the selection of adhesives for certain types of armor and protective structures; considerations for characterizing, testing and modeling adhesives.

  15. Structural effects of insulin-loading into HII mesophases monitored by electron paramagnetic resonance (EPR), small angle X-ray spectroscopy (SAXS), and attenuated total reflection Fourier transform spectroscopy (ATR-FTIR).

    Science.gov (United States)

    Mishraki, Tehila; Ottaviani, Maria Francesca; Shames, Alexander I; Aserin, Abraham; Garti, Nissim

    2011-06-30

    Insulin entrapment within a monoolein-based reverse hexagonal (H(II)) mesophase was investigated under temperature-dependent conditions at acidic (pH 3) and basic (pH 8) conditions. Studying the structure of the host H(II) system and the interactions of insulin under temperature-dependent conditions has great impact on the enhancement of its thermal stabilization and controlled release for the purposes of transdermal delivery. Small angle X-ray spectroscopy (SAXS) measurements show that pH variation and/or insulin entrapment preserve the hexagonal structure and do not influence the lattice parameter. Attenuated total reflection Fourier transform spectroscopy (ATR-FTIR) spectra indicate that, although insulin interacts with hydroxyl groups of GMO in the interface region, it is not affected by pH variations. Hence different microenvironments within the H(II) mesophase were monitored by a computer-aided electron paramagnetic resonance (EPR) analysis using 5-doxylstearic acid (5-DSA) as a pH-dependent probe. The microviscosity, micropolarity, order of systems, and distribution of the probes in different microenvironments were influenced by three factors: temperature, pH, and insulin solubilization. When the temperature is increased, microviscosity and order parameters decreased at both pH 3 and 8, presenting different decrease trends. It was found that, at pH 3, the protein perturbs the lipid structure while "pushing aside" the un-ionized 5-DSA probe to fit into the narrow water cylinders. At the interface region (pH 8), the probe was distributed in two differently structured environments that significantly modifies by increasing temperature. Insulin loading within the H(II) mesophase decreased the order and microviscosity of both the microenvironments and increased their micropolarity. Finally, the EPR analysis also provides information about the unfolding/denaturation of insulin within the channel at high temperatures.

  16. Theoretical and experimental studies on in-plane stiffness of integrated container structure

    Directory of Open Access Journals (Sweden)

    Xiaoxiong Zha

    2016-03-01

    Full Text Available This article presents analytical, numerical, and experimental studies on the in-plane stiffness of container buildings. First, based on diaphragm theory, parallel corrugated direction stiffness of corrugated sheet has been deduced, and based on energy method, shear modulus of two elastic principal directions of orthotropic plate has been deduced, and through stiffness conversion method, the stiffness relationship between parallel corrugated direction and vertical corrugated direction has been obtained. Combined with container frame, the container stiffness of loading end and non-loading end, as bottom side beam fixed, has been obtained. Second, through the software Abaqus, full-scale container model has been established. The loading–displacement curve of finite element model has been compared with theoretical analysis and has a good agreement. Third, through 20 and 40 ft container, corresponding experimental verification has been done, and by comparison of container stiffness, the theoretical analysis and finite element simulation have been verified. Finally, based on verified finite element model, parametric analysis of corrugated sheet size, corrugated sheeting cross section, elasticity modulus of top side beam, and every plate action for container stiffness have been given. Research result has made feasible in design and construction of container buildings and can provide some references to corresponding specification preparation.

  17. Theoretical investigation of the structure of κ-Al2O3

    DEFF Research Database (Denmark)

    Yourdshahyan, Y.; Engberg, U.; Bengtsson, L.

    1997-01-01

    Using plane-wave pseudopotential calculations based on density-functional theory at the local-density-approximation level we investigate all the possible kappa-Al2O3 structures which are permitted by the known crystal symmetry. We find that structures with sixfold coordinated Al atoms...

  18. Experimental and theoretical investigation of a pyridine containing Schiff base: Hirshfeld analysis of crystal structure, interaction with biomolecules and cytotoxicity

    Science.gov (United States)

    Chithiraikumar, S.; Neelakantan, M. A.

    2016-03-01

    A pyridine containing Schiff base (E)-2-methoxy-6-(((pyridin-2-ylmethyl)imino)methyl) phenol (L) was isolated in single crystals. The molecular structure of L was studied by FT-IR, NMR, UV-Vis techniques, single crystal XRD analysis and computationally by DFT method. L prefers enol form in the solid state. Electronic spectrum of L was recorded in different organic solvents to investigate the dependence of tautomerism on solvent types. The polar solvents facilitate the proton transfer by decreasing the activation energy needed for transition state. Potential energy curve for the intramolecular proton transfer in the ground state is generated in gas and solution phases. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated. The percentages of various interactions were analyzed by fingerprint plots of Hirshfeld surface. The interaction of L with CT DNA was investigated under physiological conditions using UV-Vis spectroscopy, fluorescence quenching and molecular docking methods. Molecular docking studies reveal that binding of L to the groove of B-DNA is through hydrogen bonding and hydrophobic interactions. The in vitro cytotoxicity of L was carried out in two different human tumor cell lines, MCF 7 and MIA-Pa-Ca-2 exhibits moderate activity.

  19. Theoretical study of the structural stability for fcc-CHx phases using density functional theory

    Directory of Open Access Journals (Sweden)

    M Dadsetani

    2011-09-01

    Full Text Available  Recently, a new carbon modification, namly n-diamond, have been reported, whose structure is still a matter of debate. It is important to note that the synthesis of n-diamond was carried out in the presence of hydrogen or methan. In this work we evaluate the structural stability of five fcc-CHx phases by means of first-principle calculation. The total energy is obtained as a function of the isotropic, tetragonal and rhombohedral deformations for the bulk structures. First, we analyze the C2H (cuprite, CH (zincblende, CH (rocksalt and CH2 (fluorite structures.It is found that the four systems show a minimum in the total energy for the isotropic and rhombohedral deformations, but are unstable against tetragonal deformation. In the second part, we explore the structural stability of CH2 in the pyrite structure. We find that CH2 (pyrite with the hydrogen atoms defined by the internal parameter u=0.35 and a lattice parameter of 3.766 Å is elastically stable, providing a possible explanation for the experimental observation of fcc-carbon in materials prepared in the presence of hydrogen or methan. In final, we calculate density of states, band structure and EELS spectrum of CH2 (pyrite and compare them with n-diamond.

  20. Theoretical study of molecular structures, vibrational and NMR spectra on azobenzene derivatives

    Science.gov (United States)

    Karakaya, M.; Ucun, F.

    2014-02-01

    In this study, we have calculated the most stable tautomeric forms and their ground state conformers of 2,4-dihydroxyazobenzene and 2,4-dihydroxy-6-methyl-4'-nitroazobenzene molecules. Calculations show that the most preferential tautomeric forms of these molecules are azo form for 2,4-dihydroxyazobenzene and hydrazo form for 2,4-dihydroxy-6-methyl-4'-nitroazobenzene. Vibrational frequencies, 1H and 13C NMR shifts of ground state conformers of stable tautomeric forms of the molecules have been calculated by using density functional theory-B3LYP method with 6-311G(d,p) basis set. All assignments of theoretical frequencies have been performed by potential energy distribution analysis. Calculated spectral results are in a good agreement with the corresponding experimental data.

  1. Evolution of Organic Agriculture within Theoretical Frameworks of Structural Change and Transformation

    DEFF Research Database (Denmark)

    Rasmussen, Ole Horn

    it is possibly to draw a link to our initially discussion about definition of organic agriculture. The principles between conventional and organic agriculture differ. We have two kinds of rationalities. Exactly such approach is the methodological hard core in the works of Chayanov and we link to a tentative...... suggestion for working towards, as a minimum, a double definition of organic agriculture. The last "agricultural economist" is Hvelplund. Despite his position as a researcher within energy, we have different arguments for our presentation of him here. The first argument is that Hvelplund is occupied...... question. The compilation focuses on differences and similarities among the theoreticians. The compilation reflects the methodologies of Lakator (hard core), Elster (explanations) and hierarchy within the explanations (Lawson). Do the theoreticians in question contribute with a theoretical, coherent hard...

  2. Theoretical studies of the structures and local aromaticity of conjugated polycyclic hydrocarbons using three aromatic indices

    Science.gov (United States)

    Sakai, Shogo; Kita, Yuki

    2013-07-01

    The structures and local aromaticity of some conjugated polycyclic hydrocarbons (from the butadienoid, acene, and phenylene series) are studied using ab initio MO and density functional methods. The aromaticities of the molecules are estimated using three indices: the nucleus-independent chemical shift (NICS), the harmonic oscillator model of aromaticity (HOMA), and the index of deviation from aromaticity (IDA). Assessment of the relationships between the structures and the aromatic indices shows that the IDA values correspond best to the characteristics of the conjugated polycyclic hydrocarbon structures.

  3. Theoretical modeling and design of photonic structures in zeolite nanocomposites for gas sensing. Part II: volume gratings.

    Science.gov (United States)

    Cody, D; Naydenova, I

    2018-01-01

    The suitability of holographic structures fabricated in zeolite nanoparticle-polymer composite materials for gas sensing applications has been investigated. Theoretical modeling of the sensor response (i.e., change in hologram readout due to a change in refractive index modulation or thickness as a result of gas adsorption) of different sensor designs was carried out using the Raman-Nath theory and Kogelnik's coupled wave theory. The influence of a range of parameters on the sensitivity of holographically recorded surface and volume photonic structures has been studied, namely, hologram geometry, hologram thickness and spatial frequency, reconstruction wavelength, and zeolite nanoparticle refractive index. From this, the optimum fabrication conditions for both surface and volume holographic gas sensor designs have been identified. Here in Part II, results from modeling of the influence of design on the sensor response of holographically recorded volume grating structures for gas sensing applications are reported.

  4. A theoretical model of the tridimensional structure of Bacillus thuringiensis subsp. medellin Cry 11Bb toxin deduced by homology modelling

    Directory of Open Access Journals (Sweden)

    Gutierrez Pablo

    2001-01-01

    Full Text Available Cry11Bb is an insecticidal crystal protein produced by Bacillus thuringiensis subsp. medellin during its stationary phase; this ¶-endotoxin is active against dipteran insects and has great potential for mosquito borne disease control. Here, we report the first theoretical model of the tridimensional structure of a Cry11 toxin. The tridimensional structure of the Cry11Bb toxin was obtained by homology modelling on the structures of the Cry1Aa and Cry3Aa toxins. In this work we give a brief description of our model and hypothesize the residues of the Cry11Bb toxin that could be important in receptor recognition and pore formation. This model will serve as a starting point for the design of mutagenesis experiments aimed to the improvement of toxicity, and to provide a new tool for the elucidation of the mechanism of action of these mosquitocidal proteins.

  5. FTIR and Thermal Studies on Nylon-66 and 30% Glass Fibre Reinforced Nylon-66

    OpenAIRE

    Charles, Julie; Ramkumaar, G. R.; Azhagiri, S.; Gunasekaran, S.

    2009-01-01

    The present study deals with the characterization of the polymeric materials viz., nylon-66 and 30% glass fibre reinforced nylon-66 (GF Nylon-66) by employing FTIR and thermal measurements. The complete vibrational band assignment made available for nylon-66 and GF nylon-66 using FTIR spectra confirm their chemical structure. FTIR spectroscopy provides detailed information on polymer structure through the characteristic vibrational energies of the various groups present in the molecule. The t...

  6. Theoretical study of relativistic effects in the electronic structure and chemical bonding of UF6

    International Nuclear Information System (INIS)

    Onoe, Jun; Takeuchi, Kazuo; Sekine, Rika; Nakamatsu, Hirohide; Mukoyama, Takeshi; Adachi, Hirohiko.

    1992-01-01

    We have performed the relativistic molecular orbital calculation for the ground state of UF 6 , using the discrete-variational Dirac-Slater method (DV-DS), in order to elucidate the relativistic effects in the electronic structure and chemical bonding. Compared with the electronic structure calculated by the non-relativistic Hartree-Fock-Slater (DV-X α )MO method, not only the direct relativistic effects (spin-orbit splitting etc), but also the indirect effect due to the change in screening core potential charge are shown to be important in the MO level structure. From the U-F bond overlap population analysis, we found that the U-F bond formation can be explained only by the DV-DS, not by the DV-X α . The calculated electronic structure in valence energy region (-20-OeV) and excitation energies in UV region are in agreement with experiments. (author)

  7. Theoretical study of structural and electronic properties of poly(vinyl chloride nanotube inclusions

    Directory of Open Access Journals (Sweden)

    Assad Kareen Edaan

    2012-10-01

    Full Text Available The structural and electronic properties of inclusion or interconnection between NT and PVC were studied by quantum semiepirical approximation method using (PM3 self-consistent ?eld molecular orbital method. The total structural energy, HOMO level energy, LUMO level energy, band gap?(E?_g ?=E?_HOMO-E_LUMO, and dipole moment of the compounds were calculated. Increasing the distance between NT and PVC led to decline the total energy difference which led to better interconnection between NT and PVC and vice versa when the distant is decreased. Therefore the more stable compound is f. The best electronic energies were obtained at the structures 3c and 3b in the first distance respectively. The dipole moments for all structures have the following trend: b> d > c > e > f > a> g.

  8. Synthesis, electronic structure investigation of 3-pentyl-2,6-di(furan-2-yl)piperidin-4-one by FT-IR, FT-Raman and UV-Visible spectral studies and ab initio/DFT calculations.

    Science.gov (United States)

    Arockia Doss, M; Savithiri, S; Rajarajan, G; Thanikachalam, V; Anbuselvan, C

    2015-12-05

    FT-IR and FT-Raman spectra of 3-pentyl-2,6-di(furan-2-yl) piperidin-4-one (3-PFPO) were recorded in the solid phase. The structural and spectroscopic analyses of 3-PFPO were made by using B3LYP/HF level with 6-311++G(d, p) basis set. The fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Comparison of the observed fundamental vibrational frequencies of 3-PFPO with calculated results by HF and DFT methods indicates that B3LYP is superior to HF method for molecular vibrational problems. The electronic properties such as excitation energies, oscillator strength, wavelengths and HOMO-LUMO energies were obtained by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E((2))) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. In addition, MEP and atomic charges of carbon, nitrogen, oxygen and hydrogen were calculated using B3LYP/6-311++G(d, p) level theory. Moreover, thermodynamic properties (heat capacities, entropy and enthalpy) of the title compound at different temperatures were calculated in gas phase. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Theoretical Study of the Structural Phase Transition in RbCaF3

    Science.gov (United States)

    1981-09-01

    definitive knowledge of the po- tential surfaces in the hyperspace of x parameters is a great help in this respect, and can be obtained rela- tively...rapidly. In Fig. 1 we show four unit cells of the perovskite structure, which together define the primitive unit cell of the low-temperature phase...the positions of the Ca2+ and F- ions, respectively. The arrows indicate the low- FIG. 1. Four unit cells of the perovskite structure with arrows at

  10. Investigating the Theoretical Structure of the DAS-II Core Battery at School Age Using Bayesian Structural Equation Modeling

    Science.gov (United States)

    Dombrowski, Stefan C.; Golay, Philippe; McGill, Ryan J.; Canivez, Gary L.

    2018-01-01

    Bayesian structural equation modeling (BSEM) was used to investigate the latent structure of the Differential Ability Scales-Second Edition core battery using the standardization sample normative data for ages 7-17. Results revealed plausibility of a three-factor model, consistent with publisher theory, expressed as either a higher-order (HO) or a…

  11. Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran-Nair, Kiran; Shelton, William A. [Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Valiev, Marat; Kowalski, Karol, E-mail: karol.kowalski@pnnl.gov [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, K8-91, P.O. Box 999, Richland, Washington 99352 (United States); Deng, S. H. M.; Wang, Xue-Bin, E-mail: xuebin.wang@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, K8-88, P.O. Box 999, Richland, Washington 99352 (United States)

    2015-12-14

    The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI{sup −}), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  12. Probing microhydration effect on the electronic structure of the GFP chromophore anion. Photoelectron spectroscopy and theoretical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran-Nair, Kiran; Valiev, Marat; Deng, Shihu; Shelton, William A.; Kowalski, Karol; Wang, Xue B.

    2015-12-14

    The photophysics of Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI⁻), an analog of GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab-initio methods we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  13. High-pressure behaviour of selenium-based spinels and related structures - an experimental and theoretical study

    International Nuclear Information System (INIS)

    Waskowska, A; Gerward, L; Olsen, J Staun; Feliz, M; Llusar, R; Gracia, L; Marques, M; Recio, J M

    2004-01-01

    The high-pressure structural behaviour of the cubic spinel CdCr 2 Se 4 (space group Fd3barm) and tetragonal CdGa 2 Se 4 (I4bar) has been investigated experimentally and theoretically in order to understand the large difference in compressibility between the two selenides. The experimental values of the bulk modulus for these compounds are 101(2) and 48(2) GPa, respectively. These values compare well with 92 and 44 GPa obtained from first-principles calculations based on the density functional theory formalism. The observed difference in compressibility between the cubic and tetragonal structures can be understood in terms of polyhedral analysis. In a hypothetical cubic spinel structure Fd3barm), the calculated bulk modulus for CdGa 2 Se 4 is 85 GPa. This value together with the experimental and theoretical results for CdCr 2 Se 4 suggest that the selenium-based cubic spinels should have a bulk modulus about 100 GPa, which is half the value found for the oxide spinels

  14. Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

    Science.gov (United States)

    Bhaskaran-Nair, Kiran; Valiev, Marat; Deng, S. H. M.; Shelton, William A.; Kowalski, Karol; Wang, Xue-Bin

    2015-12-01

    The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI-), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  15. High-pressure behaviour of selenium-based spinels and related structures - an experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Waskowska, A [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50 422 Wroclaw (Poland); Gerward, L [Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark (Denmark); Olsen, J Staun [Niels Bohr Institute, Oersted Laboratory, University of Copenhagen, 2100 Copenhagen (Denmark); Feliz, M [Universitat Jaume I - Campus de Riu Sec, Departament de Ciences Experimentals, Apartat 224, Castellon (Spain); Llusar, R [Universitat Jaume I - Campus de Riu Sec, Departament de Ciences Experimentals, Apartat 224, Castellon (Spain); Gracia, L [Universitat Jaume I - Campus de Riu Sec, Departament de Ciences Experimentals, Apartat 224, Castellon (Spain); Marques, M [Departamento de QuImica FIsica y AnalItica, Universidad de Oviedo, E-33006 Oviedo (Spain); Recio, J M [Departamento de QuImica FIsica y AnalItica, Universidad de Oviedo, E-33006 Oviedo (Spain)

    2004-01-14

    The high-pressure structural behaviour of the cubic spinel CdCr{sub 2}Se{sub 4} (space group Fd3barm) and tetragonal CdGa{sub 2}Se{sub 4} (I4bar) has been investigated experimentally and theoretically in order to understand the large difference in compressibility between the two selenides. The experimental values of the bulk modulus for these compounds are 101(2) and 48(2) GPa, respectively. These values compare well with 92 and 44 GPa obtained from first-principles calculations based on the density functional theory formalism. The observed difference in compressibility between the cubic and tetragonal structures can be understood in terms of polyhedral analysis. In a hypothetical cubic spinel structure Fd3barm), the calculated bulk modulus for CdGa{sub 2}Se{sub 4} is 85 GPa. This value together with the experimental and theoretical results for CdCr{sub 2}Se{sub 4} suggest that the selenium-based cubic spinels should have a bulk modulus about 100 GPa, which is half the value found for the oxide spinels.

  16. Laser Spark Formamide Decomposition Studied by FT-IR Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk

    2011-01-01

    Roč. 115, č. 44 (2011), s. 12132-12141 ISSN 1089-5639 R&D Projects: GA AV ČR IAA400400705; GA AV ČR IAAX00100903; GA ČR GAP208/10/2302 Institutional research plan: CEZ:AV0Z40400503 Keywords : FT-IR spectroscopy * high-power laser * induced dielectric-breakdown Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  17. Theoretical chemistry

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    Work in theoretical chemistry was organized under the following topics: scattering theory and dynamics (elastic scattering of the rare gas hydrides, inelastic scattering in Li + H 2 , statistical theory for bimolecular collisions, model study of dissociative scattering, comparative study of elastic scattering computational methods), studies of atmospheric diatomic and triatomic species, structure and spectra of diatomic molecules, the evaluation of van der Waals forces, potential energy surfaces and structure and dynamics, calculation of molecular polarizabilities, and development of theoretical techniques and computing systems. Spectroscopic parameters are tabulated for NO 2 , N 2 O, H 2 O + , VH, and NH. Self-consistent-field wave functions were computed for He 2 in two-center and three-center bases. Rare gas hydride intermolecular potentials are shown. (9 figures, 14 tables) (U.S.)

  18. Vesicles containing ion channels on crystalline surfaces-An FTIR and surface enhanced FTIR spectroscopic study

    Science.gov (United States)

    Fischer, W. B.; Unverricht, I.; Kuhne, Ch.; Steiner, G.; Schrattenholz, A.; Maelicke, A.; Salzer, R.

    1998-06-01

    The kinetics of the adsorption of native vesicles containing the nicotinic acetylcholine receptor (nAChR) is monitored by ATR-FTIR and SEIRA spectroscopy. The membrane vesicles are adsorbed on Ge crystals. Experiments are done with neat Ge and with Ge crystals covered with a thin layer of silver clusters in order to obtain the enhancement effect of infrared adsorption. The nAChR shows β-sheet/turn structures at the interface. These results give evidence for the existence of these structures in the extracellular domains of the receptor. The potential for SEIRA in the investigation of proteins at interfaces and membrane processes is outlined.

  19. Theoretical study of the structure and the reactivity of lanthanides and actinides complexes: Activation of small molecules

    International Nuclear Information System (INIS)

    Castro, Ludovic

    2012-01-01

    This PhD thesis presents a theoretical study of the structure and the reactivity of organometallic complexes of lanthanides and actinides at the DFT level. After a general introduction of the methods of theoretical chemistry used for the modelling of organometallic reactivity, a study of the participation of 5f electrons in uranium(IV) reactivity is presented. The results show that the large core ECP can be used safely in order to treat the actinide and so that 5f electrons can be treated implicitly. Then, the reactivity of uranium(III) complexes with CO 2 and other analogous molecules is studied via multiple examples from the literature. These studies show that the steric nature of the ligands is very important and controls the reactivity. This study is then extended to samarium(II) complex. Eventually, the reactivity of a hydride complex of cerium(III) with MeOSO 2 Me is investigated and theoretical results are compared with experimental observations. (author) [fr

  20. FTIR Emission spectroscopy of surfaces

    Science.gov (United States)

    Van Woerkom, P. C. M.

    A number of vibrational spectroscopic techniques are available For the study of surfaces, such as ATR, IR reflection-absorption, IR emission, etc. Infrared emission is hardly used, although interesting applications are possible now due to the high sensitivity of Fourier transform IR (FTIR) spectrometers. Two examples, where infrared emission measurements are very fruitful, will be given. One is the investigation of the curing behaviour of organic coatings, the other is the in situ study of heterogeneously catalyzed reactions. Undoubtedly, infrared emission measurements offer a number of specific advantages in some cases. Especially the less critical demands on the sample preparation are important.

  1. Theoretical Structures of Triflic Acid-Water Clusters and the Molecular Mechanism of Proton Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Paddison, S.J.; Pratt, L.R.; Zawodzinski, T.A.

    1998-11-01

    Structural and energetic information required for recently proposed quasi-chemical theories of solution chemistry have been obtained for clusters of water with triflic acid, CF{sub 3}SO{sub 3}H(H{sub 2}O){sub n} for n=1-6. Quantum mechanical calculations on the clusters indicate that the acid proton does not dissociate with n=1 or 2 hydrating water molecules, but does dissociate for n>=3 water molecule partners. The computed minimum energy structures indicate that both ''Eigen'' (H{sub 9}O{sub 4}{sup +}) (n=3,4,6) and ''Zundel'' (H{sub 5}O{sub 2}{sup +}) (n=5) structures are likely to play a role in the molecular mechanism of acid dissociation in Nafion{reg_sign}.

  2. The Static and Molecular Structure of Barium Dibromide: A Theoretical Study

    International Nuclear Information System (INIS)

    Guerbuez, H.

    2004-01-01

    The geometry of barium dibromide was first determined by electron diffraction by Akishin and Spiridov. That study concluded that the molecule is linear, but recent modern electron diffraction and quantum chemical studies of BaBr 2 indicated that its equilibrium geometry is bent. The geometrical parameters, namely, bond lengths and bond angles of barium dibromide were calculated from different levels of computation and experimentally. In this work we have calculated the molecular structure of the BaCl 2 using the Interionic Force model. On the other hand, we have calculated the interionic potentials with two different rigid ion model potentials (RIM) which one is the Vashista-Rahman (VR) semi-empirical potential and second one is the RIM potential with parametrization of Tatlipinar. These two model potential are compared with each other by reproducing the experimental static structure. The structure calculations have been performed by solving numerically the hypernetted chain approximate of liquids

  3. Theoretical calculation and structural studies for a new nitrogen derivative from nor-lapachol

    Science.gov (United States)

    Santos, Jademilson Celestino dos; de França, José Adonias A.; do Nascimento Aquino, Lucas E.; Pereira, Mariano Alves; Mafud, Ana Carolina; Amorim Camara, Celso; Malta, Valéria R. Santos; Honório, Káthia Maria

    2014-02-01

    Nor-lapachol is a semi-synthetic naphthoquinone obtained by oxidative degradation from natural lapachol. This compound and its derivatives have been investigated for its interesting biological properties. Several naphthoquinone derivatives have been synthesized and characterized using different physicochemical and computational techniques, as such DFT, MM, spectroscopy and X-ray crystallography. Here, the structure of 2-methylamine-3-(2-methyl-1-propenyl-1-yl)-1,4-naphthoquinone was determined by X-ray crystallography and the geometry was optimized using B3LYP functional along with the 6-31G(d) basis set, which was also used in all calculations. The obtained results were compared with the structure determined experimentally, and both structures showed high similarity. Besides, some molecular properties of this compound were also calculated by using DFT as well as Hirschfeld surface.

  4. Structural and Theoretical Evidence of the Depleted Proton Affinity of the N3-Atom in Acyclovir

    Directory of Open Access Journals (Sweden)

    Esther Vílchez-Rodríguez

    2016-10-01

    Full Text Available The hydronium salt (H3O2[Cu(N7–acv2(H2O2(SO42]·2H2O (1, acv = acyclovir has been synthesized and characterized by single-crystal X-ray diffraction and spectral methods. Solvated Cu(OH2 is a by-product of the synthesis. In the all-trans centrosymmetric complex anion, (a the Cu(II atom exhibits an elongated octahedral coordination; (b the metal-binding pattern of acyclovir (acv consists of a Cu–N7(acv bond plus an (aquaO–H···O6(acv interligand interaction; and (c trans-apical/distal sites are occupied by monodentate O-sulfate donor anions. Neutral acyclovir and aqua-proximal ligands occupy the basal positions, stabilizing the metal binding pattern of acv. Each hydronium(1+ ion builds three H-bonds with O–sulfate, O6(acv, and O–alcohol(acv from three neighboring complex anions. No O atoms of solvent water molecules are involved as acceptors. Theoretical calculations of molecular electrostatic potential surfaces and atomic charges also support that the O-alcohol of the N9(acv side chain is a better H-acceptor than the N3 or the O-ether atoms of acv.

  5. Structure of small TiC n clusters: A theoretical study

    International Nuclear Information System (INIS)

    Largo, Laura; Cimas, Alvaro; Redondo, Pilar; Rayon, Victor M.; Barrientos, Carmen

    2006-01-01

    A theoretical study of the TiC n (n = 1-8) clusters has been carried out at the B3LYP/6-311+G(d) level. Molecular properties for three different isomers, namely linear, cyclic, and fan species, have been determined. The fan isomers, where the titanium atom is essentially side-bonded to the entire C n unit, are predicted to be more stable than both linear and cyclic isomers. Only for the largest studied species, TiC 8 , the cyclic isomer is located lower in energy. An even-odd parity effect in the incremental binding energies is observed for the three isomers, n-even species being in general more stable for linear and fan isomers, whereas for the cyclic species n-odd clusters are favoured. A topological analysis of the electronic charge density shows that all cyclic isomers correspond to true monocyclic rings, whereas for the fan species a variety of different connectivities has been observed

  6. Theoretical study on molecular packing and electronic structure of bi-1,3,4-oxadiazole derivatives

    KAUST Repository

    Wang, Haitao

    2014-01-01

    The molecular aggregation structure of 5,5′-bis(naphthalen-2-yl)-2,2′-bi(1,3,4-oxadiazole) (BOXD-NP) was studied by computing the intermolecular interaction potential energy surface (PES) at density functional theory level based on a dimer model. All B3LYP, CAM-B3LYP and M062x functionals can yield a reliable isolated molecular geometry. The conformation of BOXD-NP obtained with all methods is perfectly planar, indicating good conjugation ability between oxadiazole and naphthalene rings. The vibrational frequencies of BOXD-NP were also calculated using the B3LYP/6-311+G∗∗ method, which showed great consistency with the experimental observations and makes the assignments of the IR spectra more solid. It was revealed that the lowest excited state of BOXD-NP should be assigned as a highly allowed π-π∗ state by TD-DFT calculation. Considering the non-covalent interactions in molecular aggregates, the M062x functional was applied in the construction of the PES. Besides the packing structure found in the crystals, PES also predicted several stable structures, indicating that PES has great ability in guiding molecular self-assembly. Symmetry Adapted Perturbation Theory (SAPT) analysis on these energy-minimum molecular stacking structures revealed that London dispersion forces are the strongest attractive component in the binding. This journal is

  7. Synthesis, X-ray structure and theoretical investigation of 2-(2 ...

    Indian Academy of Sciences (India)

    {Co(DMF)(BQ)Cl₂} and {Mn(DMF)(BQ)Cl₂} crystallized in triclinic space group P-1. The metal(II) environment exhibits trigonal bipyramidal coordination. These complexes show presence of N–H. . .Cl, C–H...Cl hydrogen bonds and strong intramolecular C–H...O interactions. The structure parameters were calculated and ...

  8. Theoretical study of platonic crystals with periodically structured N-beam resonators

    Science.gov (United States)

    Gao, Penglin; Climente, Alfonso; Sánchez-Dehesa, José; Wu, Linzhi

    2018-03-01

    A multiple scattering theory is applied to study the properties of flexural waves propagating in a plate with periodically structured N-beam resonators. Each resonator consists of a circular hole containing an inner disk connected to background plate with N rectangular beams. The Bloch theorem is employed to obtain the band structure of a two-dimensional lattice containing a single resonator per unit cell. Also, a numerical algorithm has been developed to get the transmittance through resonator slabs infinitely long in the direction perpendicular to the incident wave. For the numerical validation, a square lattice of 2-beam resonators has been comprehensively analyzed. Its band structure exhibits several flat bands, indicating the existence of local resonances embedded in the structure. Particularly, the one featured as the fundamental mode of the inner disk opens a bandgap at low frequencies. This mode has been fully described in terms of a simple spring-mass model. As a practical application of the results obtained, a homogenization approach has been employed to design a focusing lens for flexural waves, where the index gradient is obtained by adjusting the orientation of the resonators beams. Numerical experiments performed within the framework of a three-dimensional finite element method have been employed to discuss the accuracy of the models described here.

  9. A theoretical study on the B3 phases of ZnSe: Structural and ...

    Indian Academy of Sciences (India)

    KHOIROM Kabita

    2017-06-20

    Jun 20, 2017 ... modified Becke–Johnson-generalized gradient approximation; energy band gap; density of states. PACS Nos 71.15.Mb; 71.20.–b; 71.20.Nr. 1. Introduction. Developments in computational simulations have recently made it possible to study the structural and electronic properties of compounds from the first ...

  10. Experimental and theoretical aspects of ab initio structure determination using powder diffraction techniques

    International Nuclear Information System (INIS)

    David, W.I.F.; Johnson, M.W.; Wilson, C.C.

    1988-01-01

    Neutron powder diffraction has, over the past two decades, developed into a powerful technique for the refinement of moderately complex crystal structures. The advent of a new generation of ultra-high resolution X-ray and neutron powder diffractometers, however, not only permits the refinement of more complex materials but also opens up new areas of research. Perhaps the most exciting development in powder diffraction techniques associated with high resolution is the ab initio determination of crystal structures. This has until recently been possible, in a routine way, only by single crystal studies. The compression of three dimensions of diffraction data to the one dimension of a powder diffraction pattern leads to an unavoidable loss of information. For many, but not all, crystal symmetries high resolution minimises this loss thus allowing the intensities of a sufficient number of resolved Bragg reflections from moderately complex materials to be extracted for use in structure solution by direct methods of phase determination and by Patterson methods. Recent structure determination using the high resolution powder diffractometer, HRPD, at ISIS will be presented. The inherent limitations resulting from crystal and instrumental resolution are discussed along with maximum entropy techniques that seek to optimise the information content of a powder diffraction pattern. (author) 36 refs., 1 fig., 3 tabs

  11. BIGIF: fracture mechanics code for structures. Manual 1: introduction and theoretical background

    International Nuclear Information System (INIS)

    Besuner, P.M.; Rau, S.A.; Davis, C.S.; Rogers, G.W.; Grover, J.L.; Peters, D.C.

    1981-04-01

    This report is a general description manual documenting the current version of BIGIF, a computer program designed to calculate cracked growth in a flawed structure. The first of three, this manual provides a general understanding of the program's present capabilities and includes enough information to decide whether or not to use BIGIF

  12. Theoretical studies on the electronic structure and properties of complex ceramic crystals and glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ching, Wai-Yim.

    1991-01-24

    This progress report summarizes the accomplishment of the DOE-support research program at the University of Missouri-Kansas City for the period July 1, 1991--June 30, 1992. This is the second year of a three-year renewal. The major accomplishments for the year are: (a) Initiation of fundamental studies on the electronic properties of C{sub 60} and related crystals; (b) study of electronic structures and optical properties of several important ceramic crystals, especially on AlN, SiO{sub 2} and Al{sub 2}O{sub 3}; (c) first-principles calculation of total energies and structural phase transitions in oxides, nitrides, and borides; (d) theory of magnetism in Nd{sub 2}Fe{sub 14}B permanent magnetic alloy. The major focus for the next year's effort will be on the following areas: (1) Continuation of the fundamental studies on the buckminsterfullerene system with particular emphasis on the alkali-doped superconducting fullerides. (2) Fundamental studies on the structure and properties of Boron and B-related compounds. (3) Basic studies on the structural and electronic properties of metallic glasses with particular emphasis on the magnetic glasses. (4) Further development of the first-principles OLCAO method for applications to super-complex systems.

  13. Effect of lipid composition on the structure and theoretical phase diagrams of DC-Chol/DOPE-DNA lipoplexes.

    Science.gov (United States)

    Muñoz-Ubeda, Mónica; Rodríguez-Pulido, Alberto; Nogales, Aurora; Martín-Molina, Alberto; Aicart, Emilio; Junquera, Elena

    2010-12-13

    Lipoplexes constituted by calf-thymus DNA (CT-DNA) and mixed cationic liposomes consisting of varying proportions of the cationic lipid 3β-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol hydrochloride (DC-Chol) and the zwitterionic lipid, 1,2-dioleoyl-sn-glycero-3-phosphoetanolamine (DOPE) have been analyzed by means of electrophoretic mobility, SAXS, and fluorescence anisotropy experiments, as well as by theoretically calculated phase diagrams. Both experimental and theoretical studies have been run at several liposome and lipoplex compositions, defined in terms of cationic lipid molar fraction, α, and either the mass or charge ratios of the lipoplex, respectively. The experimental electrochemical results indicate that DC-Chol/DOPE liposomes, with a mean hydrodynamic diameter of around (120 ± 10) nm, compact and condense DNA fragments at their cationic surfaces by means of a strong entropically driven electrostatic interaction. Furthermore, the positive charges of cationic liposomes are compensated by the negative charges of DNA phosphate groups at the isoneutrality L/D ratio, (L/D)(ϕ), which decreases with the cationic lipid content of the mixed liposome, for a given DNA concentration. This inversion of sign process has been also studied by means of the phase diagrams calculated with the theoretical model, which confirms all the experimental results. SAXS diffractograms, run at several lipoplex compositions, reveal that, irrespectively of the lipoplex charge ratio, DC-Chol/DOPE-DNA lipoplexes show a lamellar structure, L(α), when the cationic lipid content on the mixed liposomes α ≥ 0.4, while for a lower content (α = 0.2) the lipoplexes show an inverted hexagonal structure, H(II), usually related with improved cell transfection efficiency. A similar conclusion is reached from fluorescence anisotropy results, which indicate that the fluidity on liposome and lipoplexes membrane, also related with better transfection results, increases as long as the

  14. A game theoretic algorithm to detect overlapping community structure in networks

    Science.gov (United States)

    Zhou, Xu; Zhao, Xiaohui; Liu, Yanheng; Sun, Geng

    2018-04-01

    Community detection can be used as an important technique for product and personalized service recommendation. A game theory based approach to detect overlapping community structure is introduced in this paper. The process of the community formation is converted into a game, when all agents (nodes) cannot improve their own utility, the game process will be terminated. The utility function is composed of a gain and a loss function and we present a new gain function in this paper. In addition, different from choosing action randomly among join, quit and switch for each agent to get new label, two new strategies for each agent to update its label are designed during the game, and the strategies are also evaluated and compared for each agent in order to find its best result. The overlapping community structure is naturally presented when the stop criterion is satisfied. The experimental results demonstrate that the proposed algorithm outperforms other similar algorithms for detecting overlapping communities in networks.

  15. Synergic application of spectroscopic and theoretical methods to the chlorogenic acid structure elucidation

    Science.gov (United States)

    Marković, Svetlana; Tošović, Jelena; Dimitrić Marković, Jasmina M.

    2016-07-01

    Although chlorogenic acid (5-O-caffeoylquinic acid, 5CQA) is a dietary polyphenol known for its pharmacological and nutritional properties, its structural features have not been completely elucidated. This is the first study whose aim is to contribute to clarification of the 5CQA structure by comparing the experimental and simulated IR, Raman, 1H NMR, 13C NMR, and UV spectra. For this purpose, a comprehensive conformational analysis of 5CQA was performed to reveal its most stable conformations in the gas-state and solution (DMSO and methanol). The lowest-energy conformers were used to predict the spectra at two levels of theory: B3LYP-D3/and M06-2X/6-311+G(d,p) in combination with the CPCM solvation model. Both methods provide very good agreement between all experimental and simulated spectra, thus indicating correct arrangement of the atoms in the 5CQA molecule. The quinic moiety is characterized with directed hydrogen bonds, where the carboxylic hydrogen is not oriented towards the carbonyl oxygen of the carboxylic group, but towards the oxygen of the proximate hydroxyl group. In the gas-state the lowest-energy conformers are characterized with the O4sbnd H4 ⋯ O9‧ hydrogen bond, whereas in the solvated state the structures with the O4sbnd H4 ⋯ O10‧ hydrogen bond prevail. Knowing the fine structural details, i.e. the proper conformation of 5CQA, provides a solid base for all further investigations related to this compound.

  16. Theoretical analysis of electronic band structure of 2- to 3-nm Si nanocrystals

    Czech Academy of Sciences Publication Activity Database

    Hapala, Prokop; Kůsová, Kateřina; Pelant, Ivan; Jelínek, Pavel

    2013-01-01

    Roč. 87, č. 19 (2013), "195420-1"-"195420-13" ISSN 1098-0121 R&D Projects: GA ČR GD202/09/H041; GA ČR(CZ) GBP108/12/G108 Grant - others:AVČR(CZ) M100101207 Institutional support: RVO:68378271 Keywords : Si nanoparticles * electronic band structure * nanoparticles * luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.664, year: 2013

  17. Critical Assessment of Theoretical Calculations of Atomic Structure and Transition Probabilities: An Experimenter’s View

    Directory of Open Access Journals (Sweden)

    Elmar Träbert

    2014-03-01

    Full Text Available The interpretation of atomic observations by theory and the testing of computational predictions by experiment are interactive processes. It is necessary to gain experience with “the other side” before claims of achievement can be validated and judged. The discussion covers some general problems in the field as well as many specific examples, mostly organized by isoelectronic sequence, of what level of accuracy recently has been reached or which atomic structure or level lifetime problem needs more attention.

  18. Theoretically predicted soft x-ray emission and absorption spectra of graphitic-structured BC2N

    Science.gov (United States)

    Muramatsu, Yasuji

    Theoretical B K, C K and N K x-ray emission/absorption spectra of three possible graphitic-structured BC2N clusters are predicted based on the B2p-, C2p-, and N2p- density-of-states (DOS) calculated by discrete variational (DV)-X[alpha] molecular orbital calculations. Several prominent differences in DOS spectral features among BC2Ns, h-BN, and graphite are confirmed from comparison of calculated B2p-, C2p-, and N2p-DOS spectra. These variations in the spectra allow BC2N structures to be positively identified by high-resolution x-ray emission/absorption spectroscopy in the B K, C K, and N K regions.

  19. Theoretical analysis of improved efficiency of silicon-wafer solar cells with textured nanotriangular grating structure

    Science.gov (United States)

    Zhang, Yaoju; Zheng, Jun; Zhao, Xuesong; Ruan, Xiukai; Cui, Guihua; Zhu, Haiyong; Dai, Yuxing

    2018-03-01

    A practical model of crystalline silicon-wafer solar cells is proposed in order to enhance the light absorption and improve the conversion efficiency of silicon solar cells. In the model, the front surface of the silicon photovoltaic film is designed to be a textured-triangular-grating (TTG) structure, and the ITO contact film and the antireflection coating (ARC) of glass are coated on the TTG surface of silicon solar cells. The optical absorption spectrum of solar cells are simulated by applying the finite difference time domain method. Electrical parameters of the solar cells are calculated using two models with and without carrier loss. The effect of structure parameters on the performance of the TTG cell is discussed in detail. It is found that the thickness (tg) of the ARC, period (p) of grating, and base angle (θ) of triangle have a crucial influence on the conversion efficiency. The optimal structure of the TTG cell is designed. The TTG solar cell can produce higher efficiency in a wide range of solar incident angle and the average efficiency of the optimal TTG cell over 7:30-16:30 time of day is 8% higher than that of the optimal plane solar cell. In addition, the study shows that the bulk recombination of carriers has an influence on the conversion efficiency of the cell, the conversion efficiency of the actual solar cell with carrier recombination is reduced by 20.0% of the ideal cell without carrier recombination.

  20. Experimental and Theoretical Studies of the Structures and Interactions of Vancomycin Antibiotics with Cell Wall Analogues

    International Nuclear Information System (INIS)

    Yang, Zhibo; Vorpagel, Erich R.; Laskin, Julia

    2008-01-01

    Surface-induced dissociation (SID) of the singly protonated complex of vancomycin antibiotic with cell wall peptide analogue (N α , N # var e psilon#-diacetyl-L-Lys-D-Ala-D-Ala) was studied using a 6 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS) specially configured for SID experiments. The binding energy between the vancomycin and the peptide was obtained from the RRKM modeling of the time- and energy resolved fragmentation efficiency curves (TFECs) of the precursor ion and its fragments. Electronic structure calculations of the geometries, proton affinities and binding energies were performed for several model systems including vancomycin (V), vancomycin aglycon (VA), N α , N # var e psilon#-diacetyl-L-Lys-D-Ala-D-Ala, and non-covalent complexes of VA with N-acetyl-D-Ala-D-Ala and N α , N # var e psilon#-diacetyl-L-Lys-D-Ala-D-Ala at the B3LYP/6-31G(d) level of theory. Comparison between the experimental and computational results suggests that the most probable structure of the complex observed in our experiments corresponds to the neutral peptide bound to the vancomycin protonated at the secondary amino group of the N-methyl-leucine residue. The experimental binding energy of 30.9 ± 1.8 kcal/mol is in good agreement with the binding energy of 29.3 ± 2.5 kcal/mol calculated for the model system representing the preferred structure of the complex

  1. Structural influence in the interaction of cysteine with five coordinated copper complexes: Theoretical and experimental studies

    Science.gov (United States)

    Huerta-Aguilar, Carlos Alberto; Thangarasu, Pandiyan; Mora, Jesús Gracia

    2018-04-01

    Copper complexes of N,N,N‧,N‧-tetrakis(pyridyl-2-ylmethyl)-1,2-diaminoethane (L1) and N,N,N‧,N‧-tetrakis(pyridyl-2-ylmethyl)-1,3-diaminopropane (L2) prepared were characterized completely by different analytical methods. The X-structure of the complexes shows that Cu(II) presents in trigonal bi-pyramidal (TBP) geometry, consisting with the electronic spectra where two visible bands corresponding to five coordinated structure were observed. Thus TD-DFT was used to analyze the orbital contribution to the electronic transitions for the visible bands. Furthermore, the interaction of cysteine with the complexes was spectrally studied, and the results were explained through DFT analysis, observing that the geometrical parameters and oxidation state of metal ions play a vital role in the binding of cysteine with copper ion. It appears that the TBP structure is being changed into octahedral geometry during the addition of cysteine to the complexes as two bands (from complex) is turned to a broad band in visible region, signifying the occupation of cysteine molecule at sixth position of octahedral geometry. In the molecular orbital analysis, the existence of a strong overlapping of HOMOs (from cysteine) with LUMOs of Cu ion was observed. The total energy of the systems calculated by DFT shows that cysteine binds favorably with copper (I) than that with Cu(II).

  2. Edge effects in game-theoretic dynamics of spatially structured tumours.

    Science.gov (United States)

    Kaznatcheev, Artem; Scott, Jacob G; Basanta, David

    2015-07-06

    Cancer dynamics are an evolutionary game between cellular phenotypes. A typical assumption in this modelling paradigm is that the probability of a given phenotypic strategy interacting with another depends exclusively on the abundance of those strategies without regard for local neighbourhood structure. We address this limitation by using the Ohtsuki-Nowak transform to introduce spatial structure to the go versus grow game. We show that spatial structure can promote the invasive (go) strategy. By considering the change in neighbourhood size at a static boundary--such as a blood vessel, organ capsule or basement membrane--we show an edge effect that allows a tumour without invasive phenotypes in the bulk to have a polyclonal boundary with invasive cells. We present an example of this promotion of invasive (epithelial-mesenchymal transition-positive) cells in a metastatic colony of prostate adenocarcinoma in bone marrow. Our results caution that pathologic analyses that do not distinguish between cells in the bulk and cells at a static edge of a tumour can underestimate the number of invasive cells. Although we concentrate on applications in mathematical oncology, we expect our approach to extend to other evolutionary game models where interaction neighbourhoods change at fixed system boundaries. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. Theoretical investigations of the effect of vacancies on the geometric and electronic structures of zinc sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Yao Jinhuan, E-mail: yaojinhuan@126.com [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, Guangi 541004 (China); Li Yanwei, E-mail: lywhit@glite.edu.cn [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, Guangi 541004 (China); GuangXi Key Laboratory of New Energy and Building Energy Saving, Guilin University of Technology, Guilin, Guangxi 541004 (China); Li Ning [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, Guangi 541004 (China); Le Shiru [Natural Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150001 (China)

    2012-09-15

    The effects of S-vacancy and Zn-vacancy on the geometric and electronic structures of zinc blende ZnS are investigated by the first-principles calculation of the plane wave ultrasoft pseudopotential method based on the density functional theory. The results demonstrate that both S-vacancy and Zn-vacancy decrease the cell volume and induce slight deformation of the perfect ZnS. Furthermore, this change of geometric structure caused by Zn-vacancy is more obvious than the one due to the S-vacancy. The formation energy of S-vacancy is higher than that of Zn-vacancy, indicating that Zn-vacancy is easier to form than S-vacancy in ZnS crystal. Electronic structure analysis shows that Zn-vacancy increases the band-gap of ZnS from 2.03 eV to 2.15 eV, while the S-vacancy has almost no effect on the band-gap of ZnS. Bond population analysis shows that Zn-vacancy increases covalence character of the Zn-S bonds around Zn-vacancy, while S-vacancy shows a relatively weak effect on the covalence character of Zn-S bonds.

  4. A theoretical quest for high temperature superconductivity on the example of low-dimensional carbon structures.

    Science.gov (United States)

    Wong, C H; Lortz, R; Buntov, E A; Kasimova, R E; Zatsepin, A F

    2017-11-17

    High temperature superconductivity does not necessarily require correlated electron systems with complex competing or coexisting orders. Instead, it may be achieved in a phonon-mediated classical superconductor having a high Debye temperature and large electronic density of states at the Fermi level in a material with light atoms and strong covalent bonds. Quasi-1D conductors seem promising due to the Van Hove singularities in their electronic density of states. In this sense, quasi-1D carbon structures are good candidates. In thin carbon nanotubes, superconductivity at ~15 K has been reported, and it is likely the strong curvature of the graphene sheet which enhances the electron-phonon coupling. We use an ab-initio approach to optimize superconducting quasi-1D carbon structures. We start by calculating a T c of 13.9 K for (4.2) carbon nanotubes (CNT) that agrees well with experiments. Then we reduce the CNT to a ring, open the ring to form chains, optimize bond length and kink structure, and finally form a new type of carbon ring that reaches a T c value of 115 K.

  5. Theoretical analysis of the spatio-temporal structure of bone multicellular units

    International Nuclear Information System (INIS)

    Buenzli, P R; Pivonka, P; Gardiner, B S; Smith, D W; Dunstan, C R; Mundy, G R

    2010-01-01

    Bone multicellular units (BMUs) maintain the viability of the skeletal tissue by coordinating locally the sequence of bone resorption and bone formation performed by cells of the osteoclastic and osteoblastic lineage. Understanding the emergence and the net bone balance of such structured microsystems out of the complex network of biochemical interactions between bone cells is fundamental for many bone-related diseases and the evaluation of fracture risk. Based on current experimental knowledge, we propose a spatio-temporal continuum model describing the interactions of osteoblastic and osteoclastic cells. We show that this model admits travelling-wave-like solutions with well-confined cell profiles upon specifying external conditions mimicking the environment encountered in cortical bone remodelling. The shapes of the various cell concentration profiles within this travelling structure are intrinsically linked to the parameters of the model such as differentiation, proliferation, and apoptosis rates of bone cells. The internal structure of BMUs is reproduced, allowing for experimental calibration. The spatial distribution of the key regulatory factors can also be exhibited, which in diseased states could give hints as to the biochemical agent most accountable for the disorder.

  6. Theoretical prediction of familial amyotrophic lateral sclerosis missense mutation effects on Cu/Zn superoxide dismutase structural stability

    Energy Technology Data Exchange (ETDEWEB)

    Potier, M.; Tu, Y. [Universite de Montreal, Quebec (Canada)

    1994-09-01

    Cu/Zn superoxide dismutase (SOD) deficiency is associated with the progressive paralytic disorder familial amyotrophic lateral sclerosis (FALS). Fifteen missense mutations in the SOD gene were identified in several patients. These mutations may prevent correct promoter folding or hamper homodimer formation necessary for SOD activity. To understand the effect of the missense mutations on SOD structure and function, we used a theoretical analysis of structural effects based on two predictive methods using the modeled tertiary structure of human SOD. The first method uses the TORSO program which optimizes amino acid side-chains repacking in both wild-type and mutant SODs and calculates protein internal packing energy. The second method uses a hydrophobicity scale of the amino acid residues and considers both solvent accessibility and hydrophobic nature of residue substitutions to compute a stabilization energy change ({delta}E). These predictive methods have been tested in 187 single and multiple missense mutants of 8 proteins (T4 lysozyme, human carbonic anhydrase II, chymotrypsin inhibitor 2, f1 gene V protein, barnase, {lambda}-repressor, chicken and human lysozymes) with experimentally determined thermostability. The overall prediction accuracy with these proteins was 88%. Analysis of FALS missense mutations {delta}E predicts that 14 of 15 mutations destabilize the SOD structure. The other missense mutation is located at the homodimer interface and may hinder dimer formation. This approach is applicable to any protein with known tertiary structure to predict missense mutation effects on protein stability.

  7. Theoretical Studies on the Electronic Structures and Properties of Complex Ceramic Crystals and Novel Materials

    Energy Technology Data Exchange (ETDEWEB)

    Ching, Wai-Yim

    2012-01-14

    This project is a continuation of a long program supported by the Office of Basic Energy Science in the Office of Science of DOE for many years. The final three-year continuation started on November 1, 2005 with additional 1 year extension to October 30, 2009. The project was then granted a two-year No Cost Extension which officially ended on October 30, 2011. This report covers the activities within this six year period with emphasis on the work completed within the last 3 years. A total of 44 papers with acknowledgement to this grant were published or submitted. The overall objectives of this project are as follows. These objectives have been evolved over the six year period: (1) To use the state-of-the-art computational methods to investigate the electronic structures of complex ceramics and other novel crystals. (2) To further investigate the defects, surfaces/interfaces and microstructures in complex materials using large scale modeling. (3) To extend the study on ceramic materials to more complex bioceramic crystals. (4) To initiate the study on soft condensed matters including water and biomolecules. (5) To focus on the spectroscopic studies of different materials especially on the ELNES and XANES spectral calculations and their applications related to experimental techniques. (6) To develop and refine computational methods to be effectively executed on DOE supercomputers. (7) To evaluate mechanical properties of different crystals and those containing defects and relate them to the fundamental electronic structures. (8) To promote and publicize the first-principles OLCAO method developed by the PI (under DOE support for many years) for applications to large complex material systems. (9) To train a new generation of graduate students and postdoctoral fellows in modern computational materials science and condensed matter physics. (10) To establish effective international and domestic collaborations with both experimentalists and theorists in materials

  8. Theoretical studies on the molecular structure, conformational preferences, topological and vibrational analysis of allicin

    Science.gov (United States)

    Durlak, Piotr; Berski, Sławomir; Latajka, Zdzisław

    2016-01-01

    The molecular structure, conformational preferences, topological and vibrational analysis of allicin has been investigated at two different approaches. Calculations have been carried out on static (DFT and MP2) levels with an assortment of Dunning's basis sets and dynamic CPMD simulations. In this both case within the isolated molecule approximation. The results point out that at least twenty different conformers coexist on the PES as confirmed by the flexible character of this molecule. The topological analysis of ELF showed very similar nature of the Ssbnd S and Ssbnd O bonds. The infrared spectrum has been calculated, and a comparative vibrational analysis has been performed.

  9. New five coordinated supramolecular structured cadmium complex as precursor for CdO nanoparticles: Synthesis, crystal structure, theoretical and 3D Hirshfeld surface analyses

    Science.gov (United States)

    Ghanbari Niyaky, S.; Montazerozohori, M.; Masoudiasl, A.; White, J. M.

    2017-03-01

    In this paper, a combined experimental and theoretical study on a new CdLBr2 complex (L = N1-(2-bromobenzylidene)-N2-(2-((E)-(2-bromobenzylidene) amino)ethyl) ethane-1,2-diamine) synthesized via template method, is described. The crystal structure analysis of the complex indicates that, the Cd(II) ion is centered in a distorted square pyramidal space constructed by three iminic nitrogens of the ligand as well as two bromide anions. More analysis of crystal packing proposed a supramolecular structure stabilized by some non-covalent interactions such as Br⋯Br and Xsbnd H⋯Br (X = N and C) in solid state. Furthermore, 3D Hirshfeld surface analyses and DFT studies were applied for theoretical investigation of the complexes. Theoretical achievements were found in a good agreement with respect to the experimental data. To evaluate the nature of bonding and the strength of the intra and inter-molecular interactions a natural bond orbital (NBO) analysis on the complex structure was performed. Time dependent density functional theory (TD-DFT) was also applied to predict the electronic spectral data of the complex as compared with the experimental ones. CdLBr2 complex as nano-structure compound was also prepared under ultrasonic conditions and characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). Finally, it was found that the cadmium complex can be used as a suitable precursor for preparation of CdO nanoparticles via calcination process at 600 °C under air atmosphere.

  10. FTIR Calibration Methods and Issues

    Science.gov (United States)

    Perron, Gaetan

    Over the past 10 years, several space-borne FTIR missions were launched for atmospheric research, environmental monitoring and meteorology. One can think of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) launched by the European Space Agency, the Atmospheric Chemistry Experiment (ACE) launched by the Canadian Space Agency, the Tropospheric Emission Spectrometer (TES) launched by NASA and the Infrared Atmospheric Sounding Interferometer (IASI) launched by Eumetsat in Europe. Others are near to be launched, namely the Cross-track Infrared Sounder (CrIS) from the Integrated Program Of- fice in the United States and the Thermal And Near infrared Sensor for carbon Observation (TANSO) from the Japan Aerospace Exploration Agency. Moreover, several missions under definition foresee the use of this technology as sensor, e.g. Meteosat Third Generation (MTG), Eumetsat Polar System (EPS) and the Premier mission, one of the six candidates of the next ESA Earth Explorer Core Mission. In order to produce good quality products, calibration is essential. Calibrated data is the output of three main sub-systems that are tightly coupled: the instrument, the calibration targets and the level 1B processor. Calibration requirements must be carefully defined and propagated to each sub-system. Often, they are carried out by different parties which add to the complexity. Under budget and schedule pressure, some aspects are sometimes neglected and jeopardized final quality. For space-borne FTIR, level 1B outputs are spectra that are radiometrically, spectrally calibrated and geolocated. Radiometric calibration means to assign an intensity value in units to the y-axis. Spectral calibration means to assign to the x-axis the proper frequency value in units. Finally, geolocated means to assign a target position over the earth geoid i.e. longitude, latitude and altitude. This paper will present calibration methods and issues related to space-borne FTIR missions, e.g. two

  11. Systematic review, structural analysis, and new theoretical perspectives on the role of serotonin and associated genes in the etiology of psychopathy and sociopathy

    NARCIS (Netherlands)

    Yildirim, B.O.; Derksen, J.J.L.

    2013-01-01

    Since its theoretical inception, psychopathy has been considered by philosophers, clinicians, theorists, and empirical researchers to be substantially and critically explained by genetic factors. In this systematic review and structural analysis, new hypotheses will be introduced regarding gene–gene

  12. Structural effects on the oxidation of soot particles by O2: Experimental and theoretical study

    KAUST Repository

    Raj, Abhijeet

    2013-09-01

    Soot particles are composed of polycyclic aromatic hydrocarbons (PAHs), which have either planar or curved structures. The oxidation behaviors of soot particles differ depending on their structures, arrangement of PAHs, and the type of surface functional groups. The oxidation rate of curved PAHs in soot is thought to be higher than that of planar ones. To understand the role that PAH structure plays in soot reactivity towards O2, experimental studies are conducted on two types of commercially produced soot, Printex-U and Fullerene soot, using high resolution transmission electron microscopy, electron energy loss spectroscopy, thermo-gravimetric analysis and elemental analysis. The relative concentrations of active sites, oxygenated functional groups, aliphatics and aromatics present in soots are evaluated. The activation energies for soot oxidation at different conversion levels are determined. The average activation energies of the two soots are found to differ by 26kJ/mol. To understand the reason for this difference, quantum calculations using density functional (B3LYP) and Hartree-Fock theories are conducted to study the reaction pathways of the oxidation by O2 of planar and curved PAHs using 4-pyrenyl and 1-corannulenyl as their model molecules, respectively. The energetically preferred channels for curved PAH oxidation differ from the planar one. The addition of O2 on a radical site of a six-membered ring to form a peroxyl radical is found to be barrierless for both the model PAHs. For peroxyl decomposition, three pathways are suggested, each of which involve the activation energies of 108, 170 and 121kJ/mol to form stable molecules in the case of planar PAH, and 94, 155 and 125kJ/mol in the case of curved PAH. During the oxidation of a five-membered ring, to form stable molecules, the activation energies of 90kJ/mol for the curved PAH and 169kJ/mol for the planar PAH relative to the energy of the peroxyl radical are required. The low activation barriers of

  13. Theoretical Investigation of Subwavelength Gratings and Vertical Cavity Lasers Employing Grating Structures

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza

    . Though both sides of the grating layer are not surrounded by low refractive-index materials as in high-index-contrast gratings (HCGs), the HG can provide a near-unity reflectivity over a broader wavelength range than HCGs, or work as a resonator with a quality (Q) factor as high as 109. The physics...... behind these reflector and resonator properties are studied thoroughly. A HG structure comprising a III-V cap layer with a gain material and a Si grating layer enables the realization of a compact vertical cavity laser integrated on Si platform, which has a superior thermal property and fabrication......-factor is investigated, which shows that the uncertainty in the Q-factor can be several orders of magnitude larger than the uncertainty in the resonance frequency. Next, the HG is shown to possess a near-unity reflectivity in a broad wavelength range, which can be broader than the HCG, since the cap layer introduces...

  14. Structure and property relationships of amorphous CN sub x a joint experimental and theoretical study

    CERN Document Server

    Santos, M C D

    2000-01-01

    Amorphous CN sub x and CN sub x :H have been prepared by the ion beam assisted deposition technique. Samples were characterized through X-ray and UV photoemission, IR absorption and Raman spectroscopies. These spectra have been interpreted with the aid of quantum chemical calculations based upon the Hartree-Fock theory on several molecular models. The understanding of the electronic and structural properties of the amorphous alloy as a function of nitrogen content could help in the task of synthesizing the metastable silicon-nitride like-phase beta-C sub 3 N sub 4 , a solid which has been predicted to be as hard as diamond. The physical picture emerging from the present study helps to clarify the difficulties in obtaining the crystalline phase of the material, suggesting new experimental directions for syntheses.

  15. Theoretical investigation of the electronic structures and carrier transport of hybrid graphene and boron nitride nanostructure

    Directory of Open Access Journals (Sweden)

    Jia-Tao Sun

    2012-09-01

    graphene and hexagonal boron nitride (C-BN nanostructures receive much research interest due to the complementary electronic properties. Graphene is a zero-gap semiconductor, while hexagonal boron nitride (h-BN is a wide gap semiconductor. Here we studied the electronic structures and carrier transport of hybrid C-BN nanostructures by using first principles calculations and deformation potential theory. We have found that the physical quantities in these systems under study, band gap, effective mass, deformation potential, and carrier mobility, can be categorised into three different families depending on the width of graphene nanoribbon. This family behavior is similar to pristine armchair graphene nanoribbon, but with slight difference from the individual component. New opportunities of designing nanoelectric devices are discussed by utilizing the quantum confinement effect based on such kind of hybrid nanostructures.

  16. Structural comparison of 1{beta}-Methylcarbapenem, Carbapenem and Penem: NMR studies and theoretical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Sunagawa, M.; Sasaki, A.; Igarashi, J.-E.; Nishimura, T. [Research Center, Sumitomo Pharmaceuticals Co., Ltd., 3-1-98 Kasugadenaka, Konohanaku, Osaka (Japan)

    1998-04-01

    Structural comparisons of meropenem (1), desmethyl meropenem (2) and the penem analogue (3) which contain the same side chains at both C-2 and C-6 were performed using {sup 1}H NMR measurements together with 3-21G* level of ab initio MO and molecular mechanics calculations. The ab initio MO calculations reproduced the skeletons of these strained {beta}-lactam rings in good agreement with the crystallographic data. {sup 1}H NMR measurements in aqueous solution together with molecular modeling studies indicated that there were conformational differences of the C-2 and C-6 side chains in this series of compounds. These observations suggested that the conformational differences could affect their biological activities. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  17. Structural comparison of 1β-Methylcarbapenem, Carbapenem and Penem: NMR studies and theoretical calculations

    International Nuclear Information System (INIS)

    Sunagawa, M.; Sasaki, A.; Igarashi, J.-E.; Nishimura, T.

    1998-01-01

    Structural comparisons of meropenem (1), desmethyl meropenem (2) and the penem analogue (3) which contain the same side chains at both C-2 and C-6 were performed using 1 H NMR measurements together with 3-21G* level of ab initio MO and molecular mechanics calculations. The ab initio MO calculations reproduced the skeletons of these strained β-lactam rings in good agreement with the crystallographic data. 1 H NMR measurements in aqueous solution together with molecular modeling studies indicated that there were conformational differences of the C-2 and C-6 side chains in this series of compounds. These observations suggested that the conformational differences could affect their biological activities. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  18. Synthesis, X-ray crystal structure and theoretical calculations of antileishmanial neolignan analogues

    International Nuclear Information System (INIS)

    Nascimento, Josenaide P. do; Santos, Lourivaldo S.; Carmo, Maria Carolina L. do; Brasil, Davi S.B.; Alves, Claudio N.; Santos, Regina Helena A.; Tozzo, Erica; Ferreira, Janaina G.

    2010-01-01

    The synthesis and X-ray crystal diffraction structure of two analogues of neolignans, 2-(4-chlorophenyl)-1-phenylethanone (20) and 2-[(4-chlorophenyl)thio]-1-(3,4-dimethoxyphenyl) propan-1-one (12) is described. The compound 12 presents activity against intracellular Leishmania donovani and Leishmania amazonensis amastigotes that cause cutaneous and visceral leishmaniasis. In addition, the density functional theory (DFT) with the B3LYP hybrid functional was employed to calculate a set of molecular descriptors for nineteen synthetic analogues of neolignans with antileishmanial activities. Afterwards, the stepwise discriminant analysis was performed to investigate possible relationship between the molecular descriptors and biological activities. Through this analysis the compounds were classified into two groups active and inactive according to their degree of biological activities, and the more important properties were charges on some key atoms, electronic affinity and ClogP. (author)

  19. Synthesis, X-ray crystal structure and theoretical calculations of antileishmanial neolignan analogues

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Josenaide P. do; Santos, Lourivaldo S.; Carmo, Maria Carolina L. do; Brasil, Davi S.B.; Alves, Claudio N., E-mail: nahum@ufpa.b [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Inst. de Ciencias Exatas e Naturais; Santos, Regina Helena A.; Tozzo, Erica; Ferreira, Janaina G. [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Inst. de Quimica

    2010-07-01

    The synthesis and X-ray crystal diffraction structure of two analogues of neolignans, 2-(4-chlorophenyl)-1-phenylethanone (20) and 2-[(4-chlorophenyl)thio]-1-(3,4-dimethoxyphenyl) propan-1-one (12) is described. The compound 12 presents activity against intracellular Leishmania donovani and Leishmania amazonensis amastigotes that cause cutaneous and visceral leishmaniasis. In addition, the density functional theory (DFT) with the B3LYP hybrid functional was employed to calculate a set of molecular descriptors for nineteen synthetic analogues of neolignans with antileishmanial activities. Afterwards, the stepwise discriminant analysis was performed to investigate possible relationship between the molecular descriptors and biological activities. Through this analysis the compounds were classified into two groups active and inactive according to their degree of biological activities, and the more important properties were charges on some key atoms, electronic affinity and ClogP. (author)

  20. Structural Change, Economic Growth and the Environmental Kuznets Curve. A Theoretical Perspective

    International Nuclear Information System (INIS)

    De Groot, H.L.F.

    1999-01-01

    The question of whether economic growth will ultimately resolve environmental problems has recently been discussed in a mainly empirical literature. One of the mechanisms that can explain the finding of an inverted U-shaped relationship between income and emissions relies on the changes in the sectoral composition of economies associated with economic growth. This paper develops a multi-sector general-equilibrium model to study the dynamic relationships between technological progress, economic development, the sectoral composition of economies and emissions. In the model, structural change is the outcome of a complex interplay between factors of demand and supply, and results from both differences in technological progress on a sectoral level and from differences in income elasticities of demand for different goods. We will derive under what conditions such changes can give rise to a hump-shaped relationship between per capita income and emissions. 39 refs

  1. Difficulties in Defining Social-Emotional Intelligence, Competences and Skills - a Theoretical Analysis and Structural Suggestion

    Directory of Open Access Journals (Sweden)

    Moana Monnier

    2015-04-01

    Full Text Available Demands related to the frequency of and time required for interactional tasks in everyday occupational routines are continuously growing. When it comes to qualifying a person’s ability to interact with others, two prototypical concepts are often used: social competences and emotional intelligence. In connection to discussions about curriculum standards in Germany, these are viewed as important attributes that should be taught, supported and if possible assessed in educational pathways toward an occupation (KMK, 2007. However, in looking for a generally approved and widely used definition, many problems arise on the inter-conceptual and intra-conceptual level, triggering implementation difficulties in educational curricula. This article highlights these difficulties by selecting five well-established key theories and comparing their communalities and differences. Analyzing definitions of intelligence, competences and skills, taking an action regulation perspective and highlighting the interdependence of social and emotional aspects, a structural system to facilitate the transfer into the educational context is proposed.

  2. Synthesis, structural, spectroscopic, anti-cancer and molecular docking studies on novel 2-[(Anthracene-9-ylmethylene)amino]-2-methylpropane-1,3-diol using XRD, FTIR, NMR, UV-Vis spectra and DFT

    Science.gov (United States)

    Pavitha, P.; Prashanth, J.; Ramu, G.; Ramesh, G.; Mamatha, K.; Venkatram Reddy, Byru

    2017-11-01

    The novel titled compound 2-[(Anthracene-9-ylmethylene)amino]-2-methylpropane-1,3-diol (AMD) has been synthesized by slow evaporation technique from mixed solvent system of methanol with anthracene-9-carbaldehyde and 2-amino-2-methylpropane-1,3-diol. The synthesized molecule AMD was characterized experimentally by single crystal XRD, FTIR, NMR and UV-Vis spectra and density functional theory (DFT) computations. The structure of the crystal has been determined as orthorhombic system with space group P 21 21 21 and the cell parameters are obtained using XRD data. The optimized ground state geometry of the molecule is determined by evaluating torsional potentials as a function of angle of free rotation around Csbnd C bonds of functional groups by DFT method employing B3LYP functional with 6-311++G(d,p) basis set. All the fundamental vibrations of the molecule are assigned unambiguously using potential energy distribution (PED) obtained in the DFT computations. The rms error between the observed and scaled frequencies is 6.20 cm-1. The values of dipole moment, polarizability and hyperpolarizability are evaluated to study the NLO behavior of the molecule. The HOMO-LUMO energies and thermodynamic parameters are also determined. The molecular electrostatic surface potential (MESP) is mapped to obtain the charge density distribution. The 1H and 13C NMR chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. UV-visible spectrum of the compound is also recorded in the region 200-800 nm to know the type of electronic transitions involved. The anti-cancer activity of AMD is determined against human breast cancer cell line MCF-7 and human prostate cancer cell line PC-3 and correlated the results with study of molecular docking against pharmacological protein IDO-1 receptor.

  3. Molecular structure of caffeine as determined by gas electron diffraction aided by theoretical calculations

    Science.gov (United States)

    Egawa, Toru; Kamiya, Akemi; Takeuchi, Hiroshi; Konaka, Shigehiro

    2006-12-01

    The molecular structure of caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) was determined by means of gas electron diffraction. The nozzle temperature was 185 °C. The results of MP2 and B3LYP calculations with the 6-31G ∗∗ basis set were used as supporting information. These calculations predicted that caffeine has only one conformer and some of the methyl groups perform low frequency internal rotation. The electron diffraction data were analyzed on this basis. The determined structural parameters ( rg and ∠ α) of caffeine are as follows: = 1.382(3) Å; r(C dbnd C) = 1.382(←) Å; r(C sbnd C) = 1.446(18) Å; r(C dbnd N) = 1.297(11) Å; = 1.459(13) Å; = 1.206(5) Å; = 1.085(11) Å; ∠N 1sbnd C 2sbnd N 3 = 116.5(11)°; ∠N 3sbnd C 4dbnd C 5 = 121. 5(13)°; ∠C 4dbnd C 5sbnd C 6 = 122.9(10)°; ∠C 4dbnd C 5sbnd N 7 = 104.7(14)°; ∠N 9-C 4=C 5 = 111.6(10)°; = 108.5(28)°. Angle brackets denote average values; parenthesized values are the estimated limits of error (3 σ) referring to the last significant digit; left arrow in parentheses means that this parameter is bound to the preceding one.

  4. Theoretical potential for low energy consumption phase change memory utilizing electrostatically-induced structural phase transitions in 2D materials

    Science.gov (United States)

    Rehn, Daniel A.; Li, Yao; Pop, Eric; Reed, Evan J.

    2018-01-01

    Structural phase-change materials are of great importance for applications in information storage devices. Thermally driven structural phase transitions are employed in phase-change memory to achieve lower programming voltages and potentially lower energy consumption than mainstream nonvolatile memory technologies. However, the waste heat generated by such thermal mechanisms is often not optimized, and could present a limiting factor to widespread use. The potential for electrostatically driven structural phase transitions has recently been predicted and subsequently reported in some two-dimensional materials, providing an athermal mechanism to dynamically control properties of these materials in a nonvolatile fashion while achieving potentially lower energy consumption. In this work, we employ DFT-based calculations to make theoretical comparisons of the energy required to drive electrostatically-induced and thermally-induced phase transitions. Determining theoretical limits in monolayer MoTe2 and thin films of Ge2Sb2Te5, we find that the energy consumption per unit volume of the electrostatically driven phase transition in monolayer MoTe2 at room temperature is 9% of the adiabatic lower limit of the thermally driven phase transition in Ge2Sb2Te5. Furthermore, experimentally reported phase change energy consumption of Ge2Sb2Te5 is 100-10,000 times larger than the adiabatic lower limit due to waste heat flow out of the material, leaving the possibility for energy consumption in monolayer MoTe2-based devices to be orders of magnitude smaller than Ge2Sb2Te5-based devices.

  5. Theoretical study of the structure and optical properties of carbon-doped rutile and anatase titanium oxides

    International Nuclear Information System (INIS)

    Kamisaka, Hideyuki; Adachi, Takahisa; Yamashita, Koichi

    2005-01-01

    The structure and optical properties of carbon-doped titanium oxides, TiO 2 , in the rutile and anatase forms have been investigated theoretically from first principles. Two possible doping sites were studied, carbon at an oxygen site (anion doping) and carbon at a titanium site (cation doping). The calculated structures suggest that cation-doped carbon atoms form a carbonate-type structure, whereas anion-doped carbon atoms do not invoke any significant structural change. A density-of-states analysis revealed three in-gap impurity states for anion doping. The optical properties of anion-doped cells qualitatively agree with the experimentally reported visible-light absorbance values. We ascribe part of the absorption to transitions from the valence band to one of the impurity states. These transitions should be able to promote photocatalytic reactions, because electron holes in the valence band are considered to be crucial for this process. Neither in-gap impurity states nor visible-light absorbance were observed in the case of cation doping. The effect of oxygen vacancies was also investigated. Introduction of oxygen vacancies into anion-doped TiO 2 populates the impurity states and thus suppresses photocatalysis. The interaction of a doped carbon atom with an oxygen vacancy at a finite spatial separation was also carried out. The possibility of either a carbon-oxygen vacancy pair or higher carbon-oxygen vacancy complex existing is discussed

  6. Structure-thermodynamics-antioxidant activity relationships of selected natural phenolic acids and derivatives: an experimental and theoretical evaluation.

    Science.gov (United States)

    Chen, Yuzhen; Xiao, Huizhi; Zheng, Jie; Liang, Guizhao

    2015-01-01

    Phenolic acids and derivatives have potential biological functions, however, little is known about the structure-activity relationships and the underlying action mechanisms of these phenolic acids to date. Herein we investigate the structure-thermodynamics-antioxidant relationships of 20 natural phenolic acids and derivatives using DPPH• scavenging assay, density functional theory calculations at the B3LYP/6-311++G(d,p) levels of theory, and quantitative structure-activity relationship (QSAR) modeling. Three main working mechanisms (HAT, SETPT and SPLET) are explored in four micro-environments (gas-phase, benzene, water and ethanol). Computed thermodynamics parameters (BDE, IP, PDE, PA and ETE) are compared with the experimental radical scavenging activities against DPPH•. Available theoretical and experimental investigations have demonstrated that the extended delocalization and intra-molecular hydrogen bonds are the two main contributions to the stability of the radicals. The C = O or C = C in COOH, COOR, C = CCOOH and C = CCOOR groups, and orthodiphenolic functionalities are shown to favorably stabilize the specific radical species to enhance the radical scavenging activities, while the presence of the single OH in the ortho position of the COOH group disfavors the activities. HAT is the thermodynamically preferred mechanism in the gas phase and benzene, whereas SPLET in water and ethanol. Furthermore, our QSAR models robustly represent the structure-activity relationships of these explored compounds in polar media.

  7. Theoretical investigations of the thermochemistry, structures, and internal rotation of conjugated polyynes

    Science.gov (United States)

    Jarowski, Peter D.

    isodesmic equations with CBS-RAD data and also with the block localized wavefunction (BLW) method. The new estimates give essentially the same vinyl (22.3 kcal/mol) and ethynyl (21.9 kcal/mol) stabilization energies in the allyl and propargyl radicals, contrary to conventional evaluations. Likewise, the vinyl and ethynyl stabilizations in di-substituted and tri-substituted radicals are similar. These conclusions are corroborated with the block localized wavefunction (BLW) method, which is used to analyze resonance stabilization energies in the radical systems and hyperconjugative stabilization energies in the reference hydrocarbons. Chapter 3 presents the structures, heats of formation, and strain energies of diacetylene (buta-1,3-diynediyl) expanded molecules computed with ab initio and molecular mechanics calculations. Expanded cubane, prismane, tetrahedrane, and expanded monocyclics and bicyclics were optimized at the HF/6-31G(d) and B3LYP/6-31G(d) levels. The heats of formation of these systems were obtained from isodesmic equations at the HF/6-31G(d) level. Heats of formation were also calculated from Benson group equivalents. The strain energies of these expanded molecules were estimated by several independent methods. An adapted MM3* molecular mechanics force field, specifically parameterized to treat conjugated acetylene units, was employed for one measure of strain energy and as an additional method for structural analysis. Expanded dodecahedrane and icosahedrane were calculated by this method. Expanded molecules were considered structurally in the context of their potential material applications. Chapter 4 addresses the computation of the rotational barriers of substituted ethynlene and butatriene as well as their geometric and electronic structures. The barriers to internal rotation of methylated, ethynylated, and vinylated butatrienes and alkenes were calculated at the CASPT2/6-31G(d)//B3LYP/6-31G(d) level. Calculated butatriene rotational barriers are lower

  8. Experimental and theoretical approaches on thermal and structural properties of Zn doped BSCCO glass ceramics

    Directory of Open Access Journals (Sweden)

    Koralay H.

    2016-03-01

    Full Text Available Thermal properties of Cu–Zn partially substituted Bi1.8Sr2Ca2Cu3.2-xZnxO10+δ (x = 0, 0.1 and 0.5 glass-ceramic systems have been investigated with the help of a differential thermal analyzer (DTA by using Johnson-Mehl-Avrami-Kolmogorov (JMAK approximation. Non-isothermal crystallization kinetics of the samples has been tested. The calculated values of activation energy of crystallization (E and Avrami parameter (n ranged between 306.1 and 338.3 kJ.mol-1 and 1.29 and 3.59, respectively. Crystallization kinetics was compared following the partial substitution, before and after Zn doping of the sample. In addition, by using a scanning electron microscope (SEM and X-ray powder diffractometer (XRD, structural properties of Zn doped BSCCO glass-ceramic samples were determined. Surface morphology of the samples was studied by SEM measurements. Lattice parameters and volume of the samples were calculated from the XRD measurements.

  9. Structure and electrochemical properties for complexes of nitrocompounds with inorganic ions: A theoretical approach.

    Science.gov (United States)

    Sviatenko, Liudmyla K; Gorb, Leonid; Hill, Frances C; Leszczynska, Danuta; Leszczynski, Jerzy

    2016-05-15

    Reduction and oxidation (redox) reactions are widely used for removal of nitrocompounds from contaminated soil and water. Structures and redox properties for complexes of nitrocompounds, such as 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO), with common inorganic ions (Na(+) , Cl(-) , NO3-) were investigated at the SMD(Pauling)/PCM(Pauling)/MPWB1K/TZVP level of theory. Atoms in molecules (AIM) theory was applied to analyze the topological properties of the bond critical points involved in the interactions between the nitrocompounds and the ions. Topological analyses show that intermolecular interactions of the types O(N)…Na(+) , C-H…Cl(-) ( ONO2-), and C…Cl(-) ( ONO2-) may be discussed as noncovalent closed-shell interactions, while N-H···Cl(-) ( ONO2-) hydrogen bonds are partially covalent in nature. Complexation causes significant decrease of redox activity of the nitrocompounds. Analysis of the reduction potentials of the complexes obtained through application of the Pourbaix diagram of an iron/water system revealed that sodium complexes of NTO might be reduced by metallic iron. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Theoretical study of structural, elastic and thermodynamic properties of CZTX (X = S and Se) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bensalem, S., E-mail: bensalemse@gmail.com [Centre de Développement des Energies Renouvelables, CDER, BP 62 Route de l’Observatoire Bouzaréah, 16340 Algiers (Algeria); Département de Physique, Faculté des Sciences, Université de Sétif 1, 19000 Sétif (Algeria); Chegaar, M. [Département de Physique, Faculté des Sciences, Université de Sétif 1, 19000 Sétif (Algeria); Laboratoire d’Optoélectronique et Composants, Université de Sétif 1, 19000 Sétif (Algeria); Maouche, D.; Bouhemadou, A. [Laboratoire de Développement de Nouveaux Matériaux et leurs Caractérisations, Université de Sétif 1, 19000 Sétif (Algeria)

    2014-03-15

    Highlights: • CZTX (X = S, Se) alloys are relatively new absorbers for solar cells applications. • Elastic and thermodynamic properties of these alloys are not well understood. • The considered types “kesterite and stannite” can coexist in experimental samples. • Elastic and thermodynamic properties of both types have been investigated. • Coexistence of both types does not influence the behavior of CZTX-based devices. -- Abstract: By means of first-principles calculation approach, structural parameters, elastic and thermodynamic properties of Copper–Zinc–Tin–(Sulphide, Selenide) or Cu{sub 2}ZnSnX{sub 4} (X = S and Se) alloys for the kesterite (KS) and stannite (ST) types have been investigated. The calculated lattice parameters are in good agreement with experimental reported data. The elastic constants are calculated for both types of both compounds using the static finite strain scheme; the pressure dependence of elastic constants is predicted. The bulk modulus, anisotropy factor, shear modulus, Young’s modulus, Lame’s coefficient and Poisson’s ratio have been estimated from the calculated single crystalline elastic constants. The analysis of B/G ratio shows that Cu{sub 2}ZnSnX{sub 4} or CZTX compounds behave as ductile. Through quasi-harmonic approximation, the temperature dependence of some thermodynamic functions and lattice heat capacity of both compounds for both types have been performed.

  11. Anatomy of a Spin: The Information-Theoretic Structure of Classical Spin Systems

    Directory of Open Access Journals (Sweden)

    Vikram S. Vijayaraghavan

    2017-05-01

    Full Text Available Collective organization in matter plays a significant role in its expressed physical properties. Typically, it is detected via an order parameter, appropriately defined for each given system’s observed emergent patterns. Recent developments in information theory, however, suggest quantifying collective organization in a system- and phenomenon-agnostic way: decomposing the system’s thermodynamic entropy density into a localized entropy, that is solely contained in the dynamics at a single location, and a bound entropy, that is stored in space as domains, clusters, excitations, or other emergent structures. As a concrete demonstration, we compute this decomposition and related quantities explicitly for the nearest-neighbor Ising model on the 1D chain, on the Bethe lattice with coordination number k = 3 , and on the 2D square lattice, illustrating its generality and the functional insights it gives near and away from phase transitions. In particular, we consider the roles that different spin motifs play (in cluster bulk, cluster edges, and the like and how these affect the dependencies between spins.

  12. Applications of structural and spectroscopic techniques to the experimental and theoretical study of new luminescent materials

    CERN Document Server

    Navarro Ahumada, G A

    2001-01-01

    momentum:DELTA J = 6 is observed for this system. A declining cascade that can reasonably explain the unsuspected related spectral intensity, in the order of 10-9, is presented and suggested although a value was predicted for the electric dipolar force of lesser than 4 orders of magnitude what was observed. This problem is discussed and a mechanism is proposed for spectral intensities associated with two emissions characterized by DELTA J = 4 (electric hexadecapole) and DELTA J = 2 (electric cuadrupole). The laboratory tests made, include synthesis by solid state reactions of Dy sup 3 sup + and Ho sup 3 sup + , type elpasolites, structural characterization using the x-ray diffraction, neutron diffraction and diffuse neutron scattering techniques, and Raman and electronic spectroscopic characterization. Results are presented for cubic systems with Cr sup 3 sup + (3d sup 3 ) and Mo sup 3 sup + (4d sup 3 ) ions, since these are privileged from a spectroscopic point of view and except for the hexacyano ion of Cr(...

  13. Electronic structure of graphene nanoribbons doped with nitrogen atoms: a theoretical insight.

    Science.gov (United States)

    Torres, A E; Fomine, S

    2015-04-28

    The electronic structure of graphene nanoribbons doped with a graphitic type of nitrogen atoms has been studied using B3LYP, B2PLYP and CAS methods. In all but one case the restricted B3LYP solutions were unstable and the CAS calculations provided evidence for the multiconfigurational nature of the ground state with contributions from two dominant configurations. The relative stability of the doped nanoribbons depends mostly on the mutual position of the dopant atoms and notably less on the position of nitrogen atoms within the nanoribbon. N-graphitic doping affects cationic states much more than anionic ones due the participation of the nitrogen atoms in the stabilization of the positive charge, resulting in a drop in ionization energies (IPs) for N-graphitic doped systems. Nitrogen atoms do not participate in the negative charge stabilization of anionic species and, therefore, the doping does not affect the electron affinities (EAs). The unrestricted B3LYP method is the method of choice for the calculation of IPs and EAs. Restricted B3LYP and B2PLYP produces unreliable results for both IPs and EAs while CAS strongly underestimates the electron affinities. This is also true for the reorganization energies where restricted B3LYP produces qualitatively incorrect results. Doping changes the reorganization energy of the nanoribbons; the hole reorganization energy is generally higher than the corresponding electron reorganization energy due to the participation of nitrogen atoms in the stabilization of the positive charge.

  14. Experimental and theoretical study of the hyperfine structure in the lower configurations in 45Sc II

    International Nuclear Information System (INIS)

    Villemoes, P.; van Leeuwen, R.; Arnesen, A.; Heijkenskjoeld, F.; Kastberg, A.; Larsson, M.O.; Kotochigova, S.A.

    1992-01-01

    We have measured the hyperfine structure (hfs) of 12 levels in the configurations 3d4s, 3d 2 , and 3d4p in singly ionized scandium by collinear fast-ion-beam--laser spectroscopy. The hfs of the four levels in the configuration 3d4s has to our knowledge not been measured before. From these levels the ions were excited to levels in the 3d4p configuration by the frequency-doubled output of a ring dye laser with an intracavity mounted LiIO 3 crystal. Levels in the 3d 2 configuration were excited to levels in the 3d4p configuration with visible laser light. The resulting magnetic dipole (A) and electric quadrupole (B) hfs constants are analyzed in Sandars-Beck effective-operator formalism. The multiconfiguration Dirac-Fock method has been used to calculate the hfs constants for levels in the configurations 3d4s, 3d5s, 3d6s, 3d 2 , and 3d4p. Within the framework of the configuration-interaction method, an approach is presented for the calculation of the core polarization, which uses a virtual basis set localized inside the core. For all levels, this approach gives better results compared to previously published calculations

  15. Stereotypes possess heterogeneous directionality: a theoretical and empirical exploration of stereotype structure and content.

    Science.gov (United States)

    Cox, William T L; Devine, Patricia G

    2015-01-01

    We advance a theory-driven approach to stereotype structure, informed by connectionist theories of cognition. Whereas traditional models define or tacitly assume that stereotypes possess inherently Group → Attribute activation directionality (e.g., Black activates criminal), our model predicts heterogeneous stereotype directionality. Alongside the classically studied Group → Attribute stereotypes, some stereotypes should be bidirectional (i.e., Group ⇄ Attribute) and others should have Attribute → Group unidirectionality (e.g., fashionable activates gay). We tested this prediction in several large-scale studies with human participants (NCombined = 4,817), assessing stereotypic inferences among various groups and attributes. Supporting predictions, we found heterogeneous directionality both among the stereotype links related to a given social group and also between the links of different social groups. These efforts yield rich datasets that map the networks of stereotype links related to several social groups. We make these datasets publicly available, enabling other researchers to explore a number of questions related to stereotypes and stereotyping. Stereotype directionality is an understudied feature of stereotypes and stereotyping with widespread implications for the development, measurement, maintenance, expression, and change of stereotypes, stereotyping, prejudice, and discrimination.

  16. The Objective Structured Clinical Examination (OSCE): AMEE Guide No. 81. Part I: an historical and theoretical perspective.

    Science.gov (United States)

    Khan, Kamran Z; Ramachandran, Sankaranarayanan; Gaunt, Kathryn; Pushkar, Piyush

    2013-09-01

    The Objective Structured Clinical Examination (OSCE) was first described by Harden in 1975 as an alternative to the existing methods of assessing clinical performance (Harden et al. 1975). The OSCE was designed to improve the validity and reliability of assessment of performance, which was previously assessed using the long case and short case examinations. Since then the use of the OSCE has become widespread within both undergraduate and postgraduate clinical education. We recognise that the introduction of the OSCE into an existing assessment programme is a challenging process requiring a considerable amount of theoretical and practical knowledge. The two parts of this Guide are designed to assist all those who intend implementing the OSCE into their assessment systems. Part I addresses the theoretical aspects of the OSCE, exploring its historical development, its place within the range of assessment tools and its core applications. Part II offers more practical information on the process of implementing an OSCE, including guidance on developing OSCE stations, choosing scoring rubrics, training examiners and standardised patients and managing quality assurance processes. Together we hope these two parts will act as a useful resource both for those choosing to implement the OSCE for the first time and also those wishing to quality assure their existing OSCE programme.

  17. A theoretical study on Love wave sensors in a structure with multiple viscoelastic layers on a piezoelectric substrate

    International Nuclear Information System (INIS)

    Liu, Jiansheng

    2014-01-01

    A theoretical method is used to analyze the performance of Love wave sensors with multiple viscoelastic guiding layers on a piezoelectric substrate. The method is based upon the theoretical model for multi-elastic-layer piezoelectric Love waves and the Maxwell–Weichert model for viscoelastic materials. The relationship between sensor performance and the characteristics of Love waves is discussed. Numerical calculation is completed for a Love wave delay line consisting of a viscoelastic SU-8 layer, an elastic SiO 2 layer, an ST-90°X quartz substrate and two interdigital transducers (IDTs) with a period of 40 μm deposited on the substrate surface. The calculated results prove that a Love wave sensor with such a two-layer structure can achieve better performance than a Love wave sensor with only one (visco)elastic or elastic guiding layer. Some interesting abnormal phenomena, such as an oscillation in mass velocity sensitivity (S mv ), are predicted at the area where tail-raising occurs in the propagation velocity. The method and the numerical results presented in this work may help in the development of a high-performing Love wave sensor with multiple layers. (papers)

  18. Theoretical study using electronic structure calculations of uranium and cerium dioxides containing defects and impurities

    International Nuclear Information System (INIS)

    Shi, Lei

    2016-01-01

    Uranium dioxide (UO 2 ) is the most widely used nuclear fuel in existing nuclear reactors around the world. While in service for energy supply, UO 2 is submitted to the neutron flux and undergoes nuclear fission chain reactions, which create large number of fission products and point defects. The study of the behavior of the fission products and point defects is important to understand the fuel properties under irradiation. We conduct electronic structure calculations based on the density functional theory (DFT) to model this radiation damage at the atomic scale. The DFT+U method is used to describe the strong correlation of the 4f electrons of cerium and 5f electrons of uranium in the materials studied (UO 2 , CeO 2 and (U, Ce)O 2 ). (U, Ce)O 2 is studied because it is considered as a low radioactive model material of mixed actinide oxides such as the MOX fuel (U, Pu)O 2 used in light water reactors and fast neutron reactors. Cerium dioxide (CeO 2 ) is studied to provide reference data of (U, Ce)O 2 . We perform a DFT+U study of point defects and gaseous fission products (Xe and Kr) in CeO 2 and compare our results to the existing ones of UO 2 . We study the bulk properties as well as the behavior of defects for (U, Ce)O 2 , and compare our results to the ones of (U, Pu)O 2 . Furthermore, for the study of defects in UO 2 , methodological improvements are explored considering the spin-orbit coupling effect and the finite-size effect of the simulation supercell. (author) [fr

  19. Theoretical modeling of structure and function of cathode catalyst layers in PEMFC

    International Nuclear Information System (INIS)

    Wang, Q.; Eikerling, M.; Song, D.; Liu, Z.

    2004-01-01

    'Full text:' In this work, we first investigate transport and reaction kinetics in single agglomerates of cathode catalyst layers in proton exchange fuel cells. Two types of spherical agglomerates are evaluated, which represent limiting structures that can be obtained by distinct synthetic procedures. One type consists of a mixture of carbon/catalyst particles and proton conducting perfluorosulfonated ionomer (PFSI). The other type consists of carbon/catalyst particles and water-filled pores. Performance of the former type is rationalized on the basis of the well-known Thiele-modulus. Characteristics of the latter type are studied using Nernst-Planck and Poisson equations. Aspects of current conversion, reactant and current distributions, and catalyst utilization are explored. In general, the PFSI-filled agglomerates exhibit more homogeneous distributions of reaction rates. Effectiveness factors for them are close to one. However, it was found that proton penetration depths in waterflooded agglomerates could be quite significant as well under certain conditions, resulting in unexpectedly high catalyst utilization. The effects of agglomerate radius and of boundary conditions at the agglomerate surface are studied. Moreover, using the same approach, we evaluate the performance of a flat PFSI-free catalyst layer with water-filled pore space. Compared with conventional composite catalyst layers impregnated with PFSI, the PFSI-free layer exhibits better performance and high Pt utilization for thicknesses less than 0.1 μm. The significance of these results for the optimization catalyst layers in view of operation conditions and synthesis methods is discussed. (author)

  20. A metacognitive tool: Theoretical and operational analysis of skills exercised in structured concept maps

    Directory of Open Access Journals (Sweden)

    Marie-Pierre Chevron

    2014-01-01

    Full Text Available Developing meaningful learning is not only difficult to achieve but also time consuming, because it requires a large number of different skills to develop and master. Many studies have shown that organizing knowledge in concept maps helps teachers and students to develop such a meaningful learning (Nesbit, J.C., Adescope, O.O., 2006. Learning with concept and knowledge maps: a meta-analysis. Rev. Educ. Res. 76:3, 413–446. Based on the work of Tyler (Tyler, R.W., 1950. Basic principles of Curriculum and Instruction. University of Chicago Press, Chicago, IL and Anderson (Anderson, L.W., Krathwohl, D.R., Airasian, P.W., Cruikshank, K.A., Mayer, R.E., Pintrich, P.R., Raths, J., Wittrock, M.C., 2001. A Taxonomy for Learning, Teaching, and Assessing: A revision of Bloom׳s Taxonomy of Educational Objectives. Longman, New York, this study proposes to characterize and to organize precisely, rigorously, and operationally in a two-dimensional matrix, the skills exercised during the elaboration of concept maps, here referred to as context-dependent and hierarchically structured concept maps (sCM. These skills correspond to those actually needed in transfer of knowledge, and the matrix could be used as an instructional tool to assist learners and teachers in this transfer. In addition it allows them to pay attention to the cognitive processes and types of knowledge involved during sCM elaboration. Making explicit the taxonomic levels of cognitive efforts implemented while organizing knowledge in a concept map could constitute a useful metacognitive tool to focus the teachers and learners׳ attention and efforts towards achieving higher-order thinking skills and meaningful learning.

  1. 3-Ishwarone, a Rare Ishwarane Sesquiterpene from Peperomia scandens Ruiz & Pavon: Structural Elucidation through a Joint Experimental and Theoretical Study

    Directory of Open Access Journals (Sweden)

    Fernando M. dos S.

    2013-10-01

    Full Text Available 3-Ishwarone, (1, a sesquiterpene with a rare ishwarane skeleton, was isolated from Peperomia scandens Ruiz & Pavon (Piperaceae. Its structure was unambiguously determined by 1D- and 2D-NMR and infrared analyses, as well as by comparative theoretical studies which involved calculations of 13C-NMR chemical shifts, using the Density Functional Theory (DFT with the mPW1PW91 hybrid functional and Pople’s 6-31G(d basis set, and of vibrational frequencies, using the B3LYP hybrid functional and triple ζ Dunning’s correlation consistent basis set (cc-pVTZ, of (1 and three of its possible diastereomers, compounds 2–4.

  2. Efficient and Low-Cost 3D Structured Light System Based on a Modified Number-Theoretic Approach

    Directory of Open Access Journals (Sweden)

    Salvi Joaquim

    2010-01-01

    Full Text Available Abstract 3D scanning based on structured light (SL has been proven to be a powerful tool to measure the three-dimensional shape of surfaces, especially in biomechanics. We define a set of conditions that an optimal SL strategy should fulfill in the case of static scenes and then we present an efficient solution based on improving the number-theoretic approach (NTA. The proposal is compared to the well-known Gray code (GC plus phase shift (PS technique and the original NTA, all satisfying the same set of conditions but obtaining significant improvements with our implementation. The technique is validated in biomechanical applications such as the scanning of a footprint left on a "foam box" typically made for that purpose, where one of the ultimate goals could be the production of a shoe insole.

  3. Group theoretical and Hamiltonian structures of integrable evolution equations in 1x1 and 2x1 dimensions

    International Nuclear Information System (INIS)

    Konopel'chenko, B.G.

    1983-01-01

    New results in investigation of the group-theoretical and hamiltonian structure of the integrable evolution equations in 1+1 and 2+1 dimensions are briefly reviewed. Main general results, such as the form of integrable equations, Baecklund transfomations, symmetry groups, are turned out to have the same form for different spectral problems. The used generalized AKNS-method (the Ablowitz Kaup, Newell and Segur method) permits to prove that all nonlinear evolution equations considered are hamiltonians. The general condition of effective application of the ACNS mehtod to the concrete spectral problem is the possibility to calculate a recursion operator explicitly. The embedded representation is shown to be a fundamental object connected with different aspects of the inverse scattering problem

  4. Fesbnd X (X = B, N) binary compounds: First-principles calculations of electronic structures, theoretic hardness and magnetic properties

    Science.gov (United States)

    Hui, Liangliang; Xie, Zhongjing; Li, Chunmei; Chen, Zhi-Qian

    2018-04-01

    The first-principles calculations are implemented to investigate the electronic structures, theoretic hardness and magnetic properties of iron borides and nitrides with four different crystal systems containing hexagonal (FeB2, ε-Fe3N), tetragonal (Fe2B, α″-Fe16N2), orthorhombic (α-FeB, θ-Fe3B, ζ-Fe2N), and cubic (zb-FeN, rs-FeN, γ‧-Fe4N, γ-Fe23B6) phase. The calculated lattice parameters using RPBE meet well with the experimental results. The cohesive energy and formation enthalpy values indicate the Fesbnd X (X = B, N) binary compounds are thermodynamically stable. Meanwhile, the h-FeB2 is most difficult phase for experimental synthesis among these interstitial compounds. Moreover, magnetic properties are discussed and show that the mean magnetic moments of o-Fe3B and c-Fe23B6 with the values of 2.227 μB and 2.256 μB per iron atom are approaching to that of pure iron (2.32 μB) while the c-Fe4N and t-Fe16N2 with the values of 2.51 and 2.48 μB are beyond that of pure α-Fe. The c-FeN phase shows nonmagnetic in zb-style while rs-type shows antiferromagnetic with a value of 2.52 μB. Furthermore, the average bonding length and Mulliken population combined with electronic structures are also analysed in this paper which provide that strong Fesbnd X and Xsbnd X covalent bonds are responsible for high hardness. Finally, the theoretic hardness of Xsbnd X, Fesbnd X and Fesbnd Fe bonds is predicted by semi empirical hardness theory.

  5. Syntheses, structural elucidation, thermal properties, theoretical quantum chemical studies (DFT and biological studies of barbituric–hydrazone complexes

    Directory of Open Access Journals (Sweden)

    Amina A. Soayed

    2015-03-01

    Full Text Available Condensation of barbituric acid with hydrazine hydrate yielded barbiturichydrazone (L which was characterized using IR, 1H NMR and mass spectra. The Co(II, Ni(II and Cu(II complexes derived from this ligand have been synthesized and structurally characterized by elemental analyses, spectroscopic methods (IR, UV–Vis and ESR and thermal analyses (TGA, DTG and DTA and the structures were further elucidated using quantum chemical density functional theory. Complexes of L were found to have the ML.nH2O stoichiometry with either tetrahedral or octahedral geometry. The ESR data showed the Cu(II complex to be in a tetragonal geometry. Theoretical investigation of the electronic structure of metal complexes at the TD-DFT/B3LYP level of theory has been carried out and discussed. The fundamental vibrational wavenumbers were calculated and a good agreement between observed and scaled calculated wavenumbers was achieved. Thermal studies were performed to deduce the stabilities of the ligand and complexes. Thermodynamic parameters, such as the order of reactions (n, activation energy ΔE∗, enthalpy of reaction ΔH∗ and entropy ΔS∗ were calculated from DTA curves using Horowitz–Metzger method. The ligand L and its complexes have been screened for their antifungal and antibacterial activities and were found to possess better biological activities compared to those of unsubstituted barbituric acid complexes.

  6. Electronic theoretical study of the influences of O adsorption on the electronic structure and optical properties of graphene

    Energy Technology Data Exchange (ETDEWEB)

    Shuang, Zhou; Guili, Liu, E-mail: LGL63@sina.cn; Dazhi, Fan

    2017-02-01

    The electronic structure and optical properties of adsorbing O atoms on graphene with different O coverage are researched using the density functional theory based upon the first-principle study to obtain further insight into properties of graphene. The adsorption energies, band structures, the density of states, light absorption coefficient and reflectivity of each system are calculated theoretically after optimizing structures of each system with different O coverage. Our calculations show that adsorption of O atoms on graphene increases the bond length of C-C which adjacent to the O atoms. When the O coverage is 9.4%, the adsorption energy (3.91 eV) is the maximum, which only increases about 1.6% higher than that of 3.1% O coverage. We find that adsorbed O atoms on pristine graphene opens up indirect gap of about 0.493–0.952 eV. Adsorbing O atoms make pristine graphene from metal into a semiconductor. When the O coverage is 9.4%, the band gap (0.952 eV) is the maximum. Comparing with pristine graphene, we find the density of states at Fermi level of O atoms adsorbing on graphene with different coverage are significantly increased. We also find that light absorption coefficient and reflectivity peaks are significantly reduced, and the larger the coverage, the smaller the absorption coefficient and reflectivity peaks are. And the blue shift phenomenon appears.

  7. Gas identification field test based on FTIR imaging spectrometer

    Science.gov (United States)

    Wang, Chensheng; Liu, Xingchao; Zhang, Zhijie; Yu, Hui

    2017-10-01

    Gas detection and identification is based on the spectral absorption peak feature, which is acquired by the spectrometer. FTIR imaging spectrometer has the advantages of high spectral resolution and good sensitivity, which are both suitable for the unknown or mixture gas identification applications, such as plume pollution monitoring, chemical agents detection and leakage detection. According to the application requirement, a dual band FTIR imaging spectrometer has been developed and verified. This FTIR imaging spectrometer combines the infrared thermal imaging sensor and Michelson interferometer to form the three dimensional data cube. Based on this instrument, the theoretical analysis and algorithm is introduced, and the numerical method is explained to illuminate the basic idea in gas identification based on spectral features. After that, the field verification test is setup and completed. Firstly, the FTIR imaging spectrometer is used to detect SF6, NH3 and the mixture gas, while the gas is exhausted out from the storage vase with a specific speed. Secondly, the instrument is delivered to the industrial area to monitor the plume emission, and analyze the components in plume. Finally, the instrument is utilized to monitoring the oil spill in ocean, and the practical maritime trial is realized. Further, the gas concentration evaluation method is discussed. Quantitative issue in gas identification is an important topic. The test results show that, based on the gas identification method introduced in this paper, FTIR imaging spectrometer can be utilized to identify the unknown gas or mixture gas in real time. The instrument will play a key role in environmental emergency and monitoring application.

  8. STRUCTURALLY-FUNCTIONAL AND SET-THEORETIC MODELS OF THE REGIONAL CONSTRUCTION CLUSTER AS A HETERARCHICAL SYSTEM

    Directory of Open Access Journals (Sweden)

    Shikul’skaya Ol’ga Mikhaylovna

    2018-01-01

    Full Text Available Subject: due to the existence of shabby and hazardous dwelling, the housing problem is one of the most relevant problems in the social sphere of the Astrakhan region. The Astrakhan regional construction cluster includes the significant number of the construction organizations, the servicing organizations, which are engaged in the training of personnel for construction, the banks and other credit institutions, which provide the population with mortgage loans, and also regional, municipal authorities and public organizations. The regional construction cluster is the developing social and economic system of heterarchical type. The heterarchy combines both elements of hierarchy and elements of the market relations. Therefore, the task of creation of a common information space of a regional construction cluster on the basis of mathematical, functional and information-logical models is relevant. Research objectives: use functional and mathematical modeling of heterarchical system of a regional construction cluster for development of its information portal. Materials and methods: for creation of structurally-functional model of a regional construction cluster, the methodology of structural analysis in notations of IDEF0, IDEF3, Swimlane was used. As a tool for structurally-functional simulation, we used CASE-tool - AllFusion Process Modeler r7. The mathematical description of logic of regional construction cluster management is based on the theory of sets. Results: the complex of functional models with the set-theoretic description of the system was developed. The business-process model in a notation of IDEF0 well reflects the process hierarchy that best describes the hierarchical communications prevailing in stable functioning of the regulated processes. For its creation the SADT technology was used. When the external disturbances affect the socio-economic system (SES, inertial hierarchical management ceases being effective and the advantage is given

  9. Pyridine and phosphonate containing ligands for stable lanthanide complexation. An experimental and theoretical study to assess the solution structure.

    Science.gov (United States)

    Mato-Iglesias, Marta; Balogh, Edina; Platas-Iglesias, Carlos; Tóth, Eva; de Blas, Andrés; Rodríguez Blas, Teresa

    2006-12-07

    We report an experimental and theoretical study of the stability and solution structure of lanthanide complexes with two novel ligands containing pyridine units and phosphonate pendant arms on either ethane-1,2-diamine (L2) or cyclohexane-1,2-diamine (L3) backbones. Potentiometric studies have been carried out to determine the protonation constants of the ligands and the stability constants of the complexes with Gd(III) and the endogenous metal ions Zn(II) and Cu(II). While the stability constant of the GdL2 complex is too high to be determined by direct pH-potentiometric titrations, the cyclohexyl derivative GdL3 has a lower and assessable stability (log K(GdL3)=17.62). Due to the presence of the phosphonate groups, various protonated species can be detected up to pH approximately 8 for both ligands and all metal ions studied. The molecular clusters [Ln(L)(H2O)](3-).19H2O (Ln=La, Nd, Ho or Lu; L=L2 or L3) were characterized by theoretical calculations at the HF level. Our calculations provide two minimum energy geometries where the ligand adopts different conformations: twist-wrap (tw), in which the ligand wraps around the metal ion by twisting the pyridyl units relative to each other, and twist-fold (tf), where the slight twisting of the pyridyl units is accompanied by an overall folding of the two pyridine units towards one of the phosphonate groups. The relative free energies of the tw and tf conformations of [Ln(L)(H2O)]3- (L=L2, L3) complexes calculated in aqueous solution (C-PCM) by using the B3LYP model indicate that the tw form is the most stable one along the whole lanthanide series for the complexes of L3, while for those of L2 only the Gd(III) complex is more stable in the tf conformation by ca. 0.5 kcal mol-1. 1H NMR studies of the Eu(III) complex of L3 show the initial formation of the tf complex in aqueous solution, which slowly converts to the thermodynamically stable tw form. The structures calculated for the Nd(III) complexes are in reasonably

  10. Structural and spectroscopic characterization of DMF complexes with nitrogen, carbon dioxide, ammonia and water. Infrared matrix isolation and theoretical studies

    Science.gov (United States)

    Sałdyka, Magdalena; Mielke, Zofia; Haupa, Karolina

    2018-02-01

    An infrared spectroscopic and MP2/6-311++G(2d,2p) study of the complexes between N,N-dimethylformamide (DMF) and nitrogen, carbon dioxide, water, ammonia trapped in solid argon matrices is reported. The 1:1 molecular complexes have been identified in the DMF/B/Ar matrices (B = N2, CO, H2O, NH3); their structures were determined by comparison of the spectra with the results of calculations. The analysis of the experimental and theoretical data indicate that the DMF-N2, CO complexes present in the matrices are stabilized by (C=)O⋯N and (C=)O⋯C van der Waals interactions. In turn, in the DMF-H2O, NH3 complexes the (C=)O⋯H(OH) and (C=)O⋯H(NH2) hydrogen bonding is present in which the carbonyl group of DMF acts as a proton acceptor. In all systems studied the C-H⋯X (X = N, C, O) bonding is a second intermolecular force stabilizing the planar complexes. Some spectral features indicate that for DMF-H2O, DMF-NH3 systems the nonplanar structures with the C=O⋯H interaction are also present. The study demonstrated the strong sensitivity of the CH stretching wavenumber to an involvement of the C-H and/or C=O groups of DMF in an intermolecular interaction.

  11. System input-output theoretic three-dimensional measurement based on circular-shaped structured light patterns

    Science.gov (United States)

    Lee, Deokwoo; Krim, Hamid

    2017-07-01

    Alternative approaches to three-dimensional (3-D) reconstruction by employing the concepts of "system identification" and "communication systems" based on structured light patterns are proposed. In addition, a sampling criterion of the light source is derived in the case of using multiple projectors because 3-D reconstruction sometimes employs multiple viewpoints (cameras) and multiple structured light sources (or projectors). To reformulate a reconstruction problem, an input-output (I/O) system theoretic is adopted, and camera(s) and light source(s) that are located at different positions are defined as the output and the input, respectively. Akin to the system identification problem, the ratio of an output to an input, the "system function," is defined as a 3-D measurement result. Alternatively, the reconstruction work can employ the concept of the "modulation and demodulation theory," and the reconstruction work can be reinterpreted as an "input estimation problem." This contribution chiefly deals with approximate reconstruction results that are sufficient for practical applications, such as 3-D object detection, clarification, recognition, and classification, rather than a perfect 3-D reconstruction itself. To that end, the development of an efficient and fast 3-D imaging system framework is proposed.

  12. Experimental and theoretical study of electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Festa, Floriane

    2013-01-01

    Matter in extreme conditions belongs to Warm Dense Matter regime which lays between dense plasma regime and condensed matter. This regime is still not well known, indeed it is very complex to generate such plasma in the laboratory to get experimental data and validate models. The goal of this thesis is to study electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy. Experimentally aluminum has reached high densities and high temperatures, up to now unexplored. An X-ray source has also been generated to probe highly compressed aluminum. Two spectrometers have recorded aluminum absorption spectra and aluminum density and temperature conditions have been deduced thanks to optical diagnostics. Experimental spectra have been compared to ab initio spectra, calculated in the same conditions. The theoretical goal was to validate the calculation method in high densities and high temperatures regime with the study of K-edge absorption modifications. We also used absorption spectra to study the metal-non metal transition which takes place at low density (density ≤ solid density). This transition could be study with electronic structure modifications of the system. (author) [fr

  13. Theoretical Study of the Feasibility of Laser Cooling the24Mg35Cl Molecule Including Hyperfine Structure and Branching Ratios.

    Science.gov (United States)

    Yang, Quan-Shun; Li, Shi-Chang; Yu, You; Gao, Tao

    2018-03-13

    The possibility of laser cooling the 24 Mg 35 Cl molecule is investigated using the electronic, rovibrational, and hyperfine structure. Twelve low-lying Λ-S electronic states of the 24 Mg 35 Cl molecule have been calculated at the multireference configuration interaction level of theory. The spin-orbit coupling effects are taken into account in the electronic structure calculations. Spectroscopic constants agree well with previously obtained theoretical and experimental values. On the basis of the potential energy curves and transition dipole moments, the highly diagonally distributed Franck-Condon factors for the A 2 Π → X 2 Σ + transition and short radiative lifetime of the A 2 Π state are determined. Then, employing a quantum effective Hamiltonian approach, we investigate the hyperfine manifolds of the X 2 Σ + state and obtain the zero-field hyperfine spectrum with the errors relative to the experimental data not exceeding 8-20 kHz. Finally, we design a laser cooling scheme with one cooling main laser beam and two repumping laser beams with modulated sidebands, which is sufficient for the implementation of efficient laser slowing and cooling of the 24 Mg 35 Cl molecule. Moreover, it is important to note that the dissociation energy (2.2593 eV) of the B 2 Σ + state is obtained for the first time at the multireference configuration interaction level. We hope that this can provide a helpful reference for experimental observation.

  14. Crystal Structure, DFT Theoretical Study and Herbicidal Activity of Novel 1,2,4-Triazole Compound Containing Cyclopropyl Group

    International Nuclear Information System (INIS)

    Sun, G.X.; Yang, M.Y.; Zaho, W.; Sun, Z.H.; Wu, H.K.

    2015-01-01

    A novel 1,2,4-triazole compound was synthesized and the chemical structure was confirmed by /sub 1/H NMR, MS and elemental analyses. The crystal structure of the 1,2,4-triazole (C/sub 13/H/sub 14/ FN/sub 3/S, Mr = 263.33) has been determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2(1)/c with a = 7.5179(15), b = 19.638(4), c = 8.4922(17)A, α = 90 Degree, β = 98.11(3)Degree, γ= 90 Degree, V = 1241.2(4)A3, Z = 4,. The herbicidal activity of 1,2,4-triazole was determined and the results showed the title compound displayed excellent herbicidal activity. Theoretical calculations of 1,2,4-triazole was carried out with B3LYP/6-31G (d,p) approximation. The optimized geometric parameters obtained by using DFT method show the best agreement with the experimental data. (author)

  15. FT-IR and XRD analysis of coal from Makum coalfield of Assam

    Indian Academy of Sciences (India)

    High sulphur coal sample from Ledo colliery of Makum coalfield, Assam, India was studied using FT-IR and XRD methods. FT-IR study shows the presence of ... Function of Radial Distribution Analysis (FRDA) indicates that coal is lignite in type and there is no evidence of graphite-like structure. The first maximum in the G() ...

  16. Inelastic and elastic neutron scattering studies of the vibrational and reorientational dynamics, crystal structure and solid-solid phase transition in [Mn(OS(CH₃)₂)₆](ClO₄)₂ supported by theoretical (DFT) calculations.

    Science.gov (United States)

    Szostak, Elżbieta; Hetmańczyk, Joanna; Migdał-Mikuli, Anna

    2015-06-15

    The vibrational and reorientational dynamics of CH3 groups from (CH3)2SO ligands in the high- and low-temperature phases of [Mn(OS(CH3)2)6](ClO4)2 were investigated by quasielastic and inelastic incoherent neutron scattering (QENS and IINS) methods. The results show that above the phase transition temperature (detected earlier by differential scanning calorimetry (DSC) at TC5(c)=222.9K on cooling and at TC5(h)=225.4K on heating) the CH3 groups perform fast (τR≈10(-12)-10(-13)s) reorientational motions. These motions start to slow down below TC5(c) Neutron powder diffraction (NPD) measurements, performed simultaneously with QENS and IINS, indicated that this phase transition is associated with a change of the crystal structure, too. Theoretical infrared absorption, Raman and inelastic incoherent neutron scattering spectra were calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311+G(d,p) basis set (on C, H, S, O atoms) for the isolated equilibrium model (isolated [Mn(DMSO)6](2+) cation and ClO4(-) anion). Calculated spectra show a good agreement with the experimental spectra (FT-IR, RS and IINS). The comparison of the results obtained by these complementary methods was made. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Structure of neutral molecules and monoanions of selected oxopurines in aqueous solutions as studied by NMR spectroscopy and theoretical calculations.

    Science.gov (United States)

    Dybiec, Katarzyna; Molchanov, Sergey; Gryff-Keller, Adam

    2011-03-17

    A methodology enabling investigation of a multicomponent tautomeric and acid-base equilibria by (13)C NMR spectroscopy supported by theoretical calculations has been proposed. The effectiveness of this method has been illustrated in a study of 2-oxopurine, 6-oxopurine (hypoxanthine), 8-oxopurine, and 2,6-dioxopurine (xanthine) in neutral and alkaline aqueous solutions. For each compound a series of (13)C NMR spectra were recorded at pH ranges in which neutral molecules, monoanions and/or dianions occurred in dynamic equilibrium. The carbon chemical shifts for these three forms of the investigated compounds were retrieved from the analysis of pH-dependence of the measured, dynamically averaged values of these parameters. The structures of several stable tautomers of the neutral and monoanionic oxopurine forms were predicted from theoretical calculations and nuclear magnetic shielding constants for (13)C nuclei in these tautomers were calculated. At both calculation steps (molecular geometry optimization and calculation of NMR parameters) the PBE1PBE/6-311++G(2d,p) level of theory was used. The populations of the most stable tautomers were determined from the experimental data analysis exploiting the fact that they were population-weighted averages of the chemical shifts of particular tautomers. It has been shown that only the oxo forms of the investigated oxopurines are present in aqueous solutions and that the determined populations in most cases remain in a qualitative agreement with the calculated free energies of the appropriate tautomers. The obtained results are in general agreement with other literature reports on oxopurine tautomerism and confirm importance of the hydration phenomena for the investigated systems. The data analysis has shown that the best compliance between theory and experiment is obtained when the hydration phenomenon is modeled by discrete hydration augmented by PCM (polarizable continuum solvation model).

  18. Nano-FTIR chemical mapping of minerals in biological materials

    Directory of Open Access Journals (Sweden)

    Sergiu Amarie

    2012-04-01

    Full Text Available Methods for imaging of nanocomposites based on X-ray, electron, tunneling or force microscopy provide information about the shapes of nanoparticles; however, all of these methods fail on chemical recognition. Neither do they allow local identification of mineral type. We demonstrate that infrared near-field microscopy solves these requirements at 20 nm spatial resolution, highlighting, in its first application to natural nanostructures, the mineral particles in shell and bone. "Nano-FTIR" spectral images result from Fourier-transform infrared (FTIR spectroscopy combined with scattering scanning near-field optical microscopy (s-SNOM. On polished sections of Mytilus edulis shells we observe a reproducible vibrational (phonon resonance within all biocalcite microcrystals, and distinctly different spectra on bioaragonite. Surprisingly, we discover sparse, previously unknown, 20 nm thin nanoparticles with distinctly different spectra that are characteristic of crystalline phosphate. Multicomponent phosphate bands are observed on human tooth sections. These spectra vary characteristically near tubuli in dentin, proving a chemical or structural variation of the apatite nanocrystals. The infrared band strength correlates with the mineral density determined by electron microscopy. Since nano-FTIR sensitively responds to structural disorder it is well suited for the study of biomineral formation and aging. Generally, nano-FTIR is suitable for the analysis and identification of composite materials in any discipline, from testing during nanofabrication to even the clinical investigation of osteopathies.

  19. Simulation and experiment of the static FTIR based on micro multi-step mirrors

    Science.gov (United States)

    Liang, Jingqiu; Liang, Zhong-zhu; Lv, Jin-guang; Fu, Jian-guo; Zheng, Ying; Feng, Cong; Wang, Wei-biao; Zhu, Wan-bin; Yao, Jin-song; Zhang, Jun

    2011-08-01

    In recent years, Fourier transform spectrometer (FTS) with small size and low mass is required in many applications with growing need for real-time and small platform spectral detection. In this paper, a micro Fourier transform infrared spectrometer (μFTIR) based on spatial modulation mode was designed. This spectrometer has the advantages of high stability and simplified configuration. It also promises optical path differences (OPD) with high precision, as MOEMS technology is used in manufacturing the key components. The simulation and the experiments with regard to this FTIR configuration have been done. Firstly, the diffraction effect of the micro multi-step mirrors (MMSMs) is studied. We discuss the influence to the reversed spectrum by different mirror widths and different diffraction distances. Secondly, we simulate and analyze the influence of the source solid angle to the spectral resolution. Thirdly, we set up the theoretical model of the collimation error which is mainly from the defocus of the optical system and analyze the result caused by the collimation error. Fourthly, a new discrete Fourier transform arithmetic using least-squares cosines progression (LSCP) is proposed which can reconstruct the spectrum with nonuniform sampled signals. Finally, the MMSMs are fabricated used the MOEMS technology and the structural parameters are tested.

  20. Structural variability in Cu(I) and Ag(I) coordination polymers with a flexible dithione ligand: Synthesis, crystal structure, microbiological and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Beheshti, Azizolla, E-mail: a.beheshti@scu.ac.ir [Department of Chemistry, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Nozarian, Kimia; Babadi, Susan Soleymani; Noorizadeh, Siamak [Department of Chemistry, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Motamedi, Hossein [Department of Biology, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Mayer, Peter [LMU München Department Chemie, Butenandtstr 5-13, D-81377 München (Germany); Bruno, Giuseppe [Dipartimento di Chimica Inorganica, Università di Messina, Vill. S. Agata, Salita Sperone 31, 98166 Messina (Italy); Rudbari, Hadi Amiri [Faculty of Chemistry, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of)

    2017-05-15

    Two new compounds namely [Cu(SCN)(µ-L)]{sub n} (1) and ([Ag (µ{sub 2}-L)](ClO{sub 4})){sub n} (2) have been synthesized at room temperature by one-pot reactions between the 1,1-(1,4-butanediyl)bis(1,3-dihydro-3-methyl-1H-imidazole- 2-thione) (L) and appropriate copper(I) and silver(I) salts. These polymers have been characterized by single crystal X-ray diffraction, XRPD, TGA, elemental analysis, infrared spectroscopy, antibacterial activity and scanning probe microscopy studies. In the crystal structure of 1, copper atoms have a distorted trigonal planar geometry with a CuS{sub 2}N coordination environment. Each of the ligands in the structure of 1 acting as a bidentate S-bridging ligand to form a 1D chain structure. Additionally, the adjacent 1D chains are interconnected by the intermolecular C-H…S interactions to create a 2D network structure. In contrast to 1, in the cationic 3D structure of 2 each of the silver atoms exhibits an AgS{sub 4} tetrahedral geometry with 4-membered Ag{sub 2}S{sub 2} rings. In the structure of 2, the flexible ligand adopts two different conformations; gauche-anti-gauche and anti-anti-anti. The antibacterial studies of these polymers showed that polymer 2 is more potent antibacterial agent than 1. Scanning probe microscopy (SPM) study of the treated bacteria was carried out to investigate the structural changes cause by the interactions between the polymers and target bacteria. Theoretical study of polymer 1 investigated by the DFT calculations indicates that observed transitions at 266 nm and 302 nm in the UV–vis spectrum could be attributed to the π→π* and MLCT transitions, respectively. - Graphical abstract: Two new Cu(I) and Ag(I) coordination polymers have been have been synthesized by one-pot reactions. Copper complex has a 2D non-covalent structure, but silver compound is a 3D coordination compound. These compounds have effective antibacterial activity. - Highlights: • Cu(I) and Ag(I) based coordination polymers

  1. Investigation of coals and coal conversion products by FT-IR methods

    Energy Technology Data Exchange (ETDEWEB)

    Romanchuk, V.V.; Ismagilov, M.S.; Korobetskii, I.A. [Clean Coal Technology and Certification Center Ltd., Kemerovo (Russian Federation)

    1996-12-31

    The influence of water content on coal pyrolysis was studied by Fourier transform infrared (FT-IR) spectroscopy. Three coals varying in rank were studied. The coal samples were previously dried at 200 C. Pyrolysis was carried out in a nitrogen flow reactor at temperature 450 C. The FT-IR examination showed that the aliphatic structures and hydroxyl functional groups were removed from chars, while aromatic hydrogen content increased during the pyrolysis. Several structural characteristics based on FT-IR data were calculated for coals and their chars. These structural characteristics showed increasing of aromatic hydrogen content during the drying.

  2. Anion Recognition by Pyrylium Cations and Thio-, Seleno- and Telluro- Analogues: A Combined Theoretical and Cambridge Structural Database Study

    Directory of Open Access Journals (Sweden)

    David Quiñonero

    2015-06-01

    Full Text Available Pyrylium salts are a very important class of organic molecules containing a trivalent oxygen atom in a six-membered aromatic ring. In this manuscript, we report a theoretical study of pyrylium salts and their thio-, seleno- and telluro- analogues by means of DFT calculations. For this purpose, unsubstituted 2,4,6-trimethyl and 2,4,6-triphenyl cations and anions with different morphologies were chosen (Cl–, NO3– and BF4–. The complexes were characterized by means of natural bond orbital and “atoms-in-molecules” theories, and the physical nature of the interactions has been analyzed by means of symmetry-adapted perturbation theory calculations. Our results indicate the presence of anion-π interactions and chalcogen bonds based on both σ- and π-hole interactions and the existence of very favorable σ-complexes, especially for unsubstituted cations. The electrostatic component is dominant in the interactions, although the induction contributions are important, particularly for chloride complexes. The geometrical features of the complexes have been compared with experimental data retrieved from the Cambridge Structural Database.

  3. Electronic structure of the candidate 2D Dirac semimetal SrMnSb2: a combined experimental and theoretical study

    Directory of Open Access Journals (Sweden)

    S. V. Ramankutty, J. Henke, A. Schiphorst, R. Nutakki, S. Bron, G. Araizi-Kanoutas, S. K. Mishra, Lei Li, Y. K. Huang, T. K. Kim, M. Hoesch, C. Schlueter, T. -L. Lee, A. de Visser, Zhicheng Zhong, Jasper van Wezel, E. van Heumen, M. S. Golden

    2018-02-01

    Full Text Available SrMnSb$_2$ is suggested to be a magnetic topological semimetal. It contains square, 2D Sb planes with non-symmorphic crystal symmetries that could protect band crossings, offering the possibility of a quasi-2D, robust Dirac semi-metal in the form of a stable, bulk (3D crystal. Here, we report a combined and comprehensive experimental and theoretical investigation of the electronic structure of SrMnSb$_2$, including the first ARPES data on this compound. SrMnSb$_2$ possesses a small Fermi surface originating from highly 2D, sharp and linearly dispersing bands (the Y-states around the (0,$\\pi$/a-point in $k$-space. The ARPES Fermi surface agrees perfectly with that from bulk-sensitive Shubnikov de Haas data from the same crystals, proving the Y$-$states to be responsible for electrical conductivity in SrMnSb$_2$. DFT and tight binding (TB methods are used to model the electronic states, and both show good agreement with the ARPES data. Despite the great promise of the latter, both theory approaches show the Y-states to be gapped above E$_F$, suggesting trivial topology. Subsequent analysis within both theory approaches shows the Berry phase to be zero, indicating the non-topological character of the transport in SrMnSb$_2$, a conclusion backed up by the analysis of the quantum oscillation data from our crystals.

  4. Theoretical Studies of Electronic Structure and Photophysical Properties of a Series of Indoline Dyes with Triphenylamine Ligand

    Directory of Open Access Journals (Sweden)

    Xue-Feng Ren

    2015-01-01

    Full Text Available To design efficient organic sensitizer, a series of D-π-A indoline dyes with different donor parts have been investigated by density functional theory (DFT and time-dependent DFT (TD-DFT approach. The molecular geometries, frontier molecular orbitals, and absorption spectra of these dyes have been systematically investigated to provide comprehensive understanding of the structure-property relationships. Compared with D149, our designed dyes have proper HOMO and LUMO energy level, narrowed HOMO-LUMO energy gap, and broadened absorption band by introducing the N(CH32 and N(phenyl2 groups at the donor part. Furthermore, the dimeric dyes and dye-(TiO26 systems have been optimized by DFT method to simulate the intermolecular interactions, as well as interaction between the dyes dimmers and semiconductor interface, respectively. Through the analyses of absorption energies (Eads, energy levels of the HOMO and LUMO, light harvesting efficiency (LHE, and the driving force of electrons injections (ΔGinject, it is found that the designed dyes should have improved optical properties by importing the N(CH32 group. This work is hoped to provide a theoretical guiding role in design of new dyes for dye-sensitized solar cells.

  5. Game Theoretic Analysis of Carbon Emission Abatement in Fashion Supply Chains Considering Vertical Incentives and Channel Structures

    Directory of Open Access Journals (Sweden)

    Longfei He

    2015-04-01

    Full Text Available We study an emission-dependent dyadic fashion supply chain made up of a supplier and a manufacturer, both of which can reduce their own component/product emissions to serve the carbon-footprint sensitive consumers. With Carbon Tax regulation, we consider four scenarios resulting from two ways in form of adopting transfer price contract and/or introducing third-party emission-reduction service (TPERS to enhance the efficiency of systematic emission reductions. We refine four models from these corresponding scenarios, which in turn constitute a decision-making framework composed of determining vertical incentives and choosing supply chain structures. By exploiting Stackelberg games in all models, we compare their emission reduction efficiencies and profitability for each pair of settings. Theoretic analysis and numerical studies show that adopting vertical transfer payment schemes can definitely benefit channel carbon footprint reduction and Pareto improvement of supply chain profitability, regardless of whether the emission-reduction service exists or not. However, whether introducing TPERS or not is heavily depending on systematic parameters when the transfer payment incentive is adopted there. We also provide insights on the sensitivity of carbon tax parameters with respect to the supply chain performance, overall carbon emission reduction, vertical incentive and TPERS adopting decision-makings.

  6. FTIR gas chromatographic analysis of perfumes

    Science.gov (United States)

    Diederich, H.; Stout, Phillip J.; Hill, Stephen L.; Krishnan, K.

    1992-03-01

    Perfumes, natural or synthetic, are complex mixtures consisting of numerous components. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques have been extensively utilized for the analysis of perfumes and essential oils. A limited number of perfume samples have also been analyzed by FT-IR gas chromatographic (GC-FTIR) techniques. Most of the latter studies have been performed using the conventional light pipe (LP) based GC-FTIR systems. In recent years, cold-trapping (in a matrix or neat) GC-FTIR systems have become available. The cold-trapping systems are capable of sub-nanogram sensitivities. In this paper, comparison data between the LP and the neat cold-trapping GC- FTIR systems is presented. The neat cold-trapping interface is known as Tracer. The results of GC-FTIR analysis of some commercial perfumes is also presented. For comparison of LP and Tracer GC-FTIR systems, a reference (synthetic) mixture containing 16 major and numerous minor constituents was used. The components of the mixture are the compounds commonly encountered in commercial perfumes. The GC-FTIR spectra of the reference mixture was obtained under identical chromatographic conditions from an LP and a Tracer system. A comparison of the two sets of data thus generated do indeed show the enhanced sensitivity level of the Tracer system. The comparison also shows that some of the major components detected by the Tracer system were absent from the LP data. Closer examination reveals that these compounds undergo thermal decomposition on contact with the hot gold surface that is part of the LP system. GC-FTIR data were obtained for three commercial perfume samples. The major components of these samples could easily be identified by spectra search against a digitized spectral library created using the Tracer data from the reference mixture.

  7. Energy profile, spectroscopic (FT-IR, FT-Raman and FT-NMR) and DFT studies of 4-bromoisophthalic acid

    Science.gov (United States)

    Arjunan, V.; Thirunarayanan, S.; Mohan, S.

    2018-04-01

    The stable conformer of 4-bromoisophthalic acid (BIPA) has been identified by potential energy profile analysis. All the structural parameters of 4-bromoisophthalic acid are determined by B3LYP method with 6-311++G**, 6-31G** and cc-pVTZ basis sets. The fundamental vibrations are analysed with the use of FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra. The harmonic vibrational frequencies are theoretically calculated and compared with experimental FTIR and FT-Raman frequencies. The 1H and 13C NMR spectra have been analysed and compared with theoretical 1H and 13C NMR chemical shifts calculated by gauge independent atomic orbital (GIAO) method. The electronic properties, such as HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies are determined by B3LYP/cc-pVTZ method. The electron density distribution and site of chemical reactivity of BIPA molecule have been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP). Stability of the molecules arising from hyperconjugative interactions, charge delocalizations have been analysed by using natural bond orbital (NBO) analysis. The thermodynamic properties and atomic natural charges of the compound are analysed and the reactive sites of the molecule are identified. The global and local reactivity descriptors are evaluated to analyse the chemical reactivity and site selectivity of molecule through Fukui functions.

  8. Surface Contamination by FTIR-PAS

    Science.gov (United States)

    Davis, Dennis M.; Hoffland, Lynn D.

    1985-12-01

    Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) is used to study the contamination of alkyd painted panels by liquids and solids. These alkyd painted panels are stainless steel panels coated with primer and an alkyd resin based paint which the Army uses for its vehicles. Portions of these panels were contaminated by dimethyl methyl phosphonate, tri-(2-ethylhexyl) phosphate, and triphenyl phosphate. The panels were then studied using FTIR-PAS, and the spectra identified.

  9. Vitamin C: an experimental and theoretical study on the gas-phase structure and ion energetics of protonated ascorbic acid.

    Science.gov (United States)

    Ricci, Andreina; Pepi, Federico; Cimino, Paola; Troiani, Anna; Garzoli, Stefania; Salvitti, Chiara; Di Rienzo, Brunella; Barone, Vincenzo

    2016-12-01

    In order to investigate the gas-phase mechanisms of the acid catalyzed degradation of ascorbic acid (AA) to furan, we undertook a mass spectrometric (ESI/TQ/MS) and theoretical investigation at the B3LYP/6-31 + G(d,p) level of theory. The gaseous reactant species, the protonated AA, [C 6 H 8 O 6 ]H + , were generated by electrospray ionization of a 10 -3  M H 2 O/CH 3 OH (1 : 1) AA solution. In order to structurally characterize the gaseous [C 6 H 8 O 6 ]H + ionic reactants, we estimated the proton affinity and the gas-phase basicity of AA by the extended Cooks's kinetic method and by computational methods at the B3LYP/6-31 + G(d,p) level of theory. As expected, computational results identify the carbonyl oxygen atom (O2) of AA as the preferred protonation site. From the experimental proton affinity of 875.0 ± 12 kJ mol -1 and protonation entropy ΔS p 108.9 ± 2 J mol -1  K -1 , a gas-phase basicity value of AA of 842.5 ± 12 kJ mol -1 at 298 K was obtained, which is in agreement with the value issuing from quantum mechanical computations. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. The spectroscopic (FT-IR, FT-Raman, UV) and first order hyperpolarizability, HOMO and LUMO analysis of 3-aminobenzophenone by density functional method.

    Science.gov (United States)

    Karabacak, M; Kurt, M; Cinar, M; Ayyappan, S; Sudha, S; Sundaraganesan, N

    2012-06-15

    In this work, experimental and theoretical study on the molecular structure and the vibrational spectra of 3-aminobenzophenone (3-ABP) is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 400-4000 cm(-1) and with Fourier Transform Raman spectrum in the region of 50-4000 cm(-1). Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. The spectroscopic (FT-IR, FT-IR gas phase, FT-Raman and UV) and NBO analysis of 4-Hydroxypiperidine by density functional method.

    Science.gov (United States)

    Sebastian, S; Sundaraganesan, N

    2010-03-01

    In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV-spectral analysis of 4-Hydroxypiperidine (4-HP). The FT-IR solid phase (4000-400 cm(-1)), FT-IR gas phase (5000-400 cm(-1)) and FT-Raman spectra (3500-50 cm(-1)) of 4-HP was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 4-HP in the ground-state have been calculated by using the density functional methods (BLYP, B3LYP) with 6-311G (d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the sigma* antibonding orbitals and E (2) energies confirms the occurrence of ICT (Intra-molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethanol solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Copyright 2009 Elsevier B.V. All rights reserved.

  12. Experimental and theoretical analysis of 2-amino 1-methyl benzimidazole molecule based on DFT

    Science.gov (United States)

    Sas, E. B.; Cevik, M.; Kurt, M.

    2017-12-01

    In this work were shown spectroscopic properties, molecular structure and electronic properties of 2-amino 1 methyl benzimidazole molecule. The theoretical calculations in the title molecule were performed with density functional theory method. Experimental wavenumber of 2-amino 1 methyl benzimidazole molecule were recorded with FT-Raman, dispersive Raman and FT-IR between 4000 and 0, 4000-400 and 4000-370 cm-1, respectively. The scaled theoretical wavenumber are assigned based on total energy distribution. Other experimental spectra were recorded in specific solvents.

  13. Effect of substituents on redox, spectroscopic and structural properties of conjugated diaryltetrazines--a combined experimental and theoretical study.

    Science.gov (United States)

    Kurach, Ewa; Djurado, David; Rimarčik, Jan; Kornet, Aleksandra; Wlostowski, Marek; Lukeš, Vladimir; Pécaut, Jacques; Zagorska, Malgorzata; Pron, Adam

    2011-02-21

    Two series of new soluble conjugated compounds containing tetrazine central ring have been synthesized. The three-ring compounds have been synthesized by the reaction of aryl cyanide (where aryl = thienyl, alkylthienyl, phenyl or pyridyl) with hydrazine followed by oxidation of the intermediate product with diethyl azodicarboxylate. The five-ring compounds have been prepared using two pathways: (i) reaction of 5-cyano-2,2'-bithiophene (or its alkyl derivative) with hydrazine; (ii) via Suzuki or Stille coupling of 3,6-bis(5-bromo-2-thienyl)-1,2,4,5-tetrazine with a stannyl or boronate derivative of alkylthiophene. UV-vis spectroscopic properties of the synthesized compounds are strongly dependent on the nature of the aryl group, the position of the solubilizing substituent and the length of the molecule, showing the highest bathochromic shift (λ(max) > 440 nm) for five-ring compounds with alkyl groups attached to C(α) carbon in the terminal thienyl ring. An excellent linear correlation has been found for spectroscopically determined and theoretically calculated (TD-B3LYP/6-31G*) excitation energies. With the exception of dipyridyl derivative, the calculated lowest unoccupied molecular orbital (LUMO) level of the investigated molecules changes within a narrow range (from -2.63 to -2.41 eV), in line with the electrochemical data, which show a reversible reduction process with the redox potential varying from -1.23 V to -1.33 V (vs. Fc/Fc(+)). The electrochemically determined positions of the LUMO levels are consistently lower by 0.9 to 1.2 eV with respect to the calculated ones. All molecules readily crystallize. Single crystal studies of 3,6-bis(2,2'-bithien-5-yl)-1,2,4,5-tetrazine show that it crystallizes in a P2(1)/c space group whose structural arrangement is not very favorable to the charge carriers flow within the crystal. Powder diffraction studies of other derivatives have shown that their structural organization is sensitive to the position of the

  14. Molecular structure, spectroscopic (FTIR, FT-Raman, 13C and 1H NMR, UV), polarizability and first-order hyperpolarizability, HOMO-LUMO analysis of 2,4-difluoroacetophenone.

    Science.gov (United States)

    Jeyavijayan, S

    2015-02-05

    The FTIR and FT-Raman spectra of 2,4-difluoroacetophenone (DFAP) have been recorded in the regions 4000-400 cm(-1) and 3500-50 cm(-1), respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by density functional theory (DFT/B3LYP) method with 6-31+G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of DFAP is also reported based on total energy distribution (TED). Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The MEP map shows the negative potential sites are on oxygen atom as well as the positive potential sites are around the hydrogen atoms. The UV-Vis spectral analysis of DFAP has also been done which confirms the charge transfer of DFAP. The chemical shifts of H atoms and C atoms were calculated using NMR analysis. Furthermore, the polarizability, the first hyperpolarizability and total dipole moment of the molecule have been calculated. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Synthesis, Structural Characterization, and Thermal Properties of the Poly(methylmethacrylate/δ-FeOOH Hybrid Material: An Experimental and Theoretical Study

    Directory of Open Access Journals (Sweden)

    Silviana Corrêa

    2016-01-01

    Full Text Available The δ-FeOOH/PMMA nanocomposites with 0.5 and 2.5 wt.% of δ-FeOOH were prepared by grafting 3-(trimethoxysilylpropyl methacrylate on the surface of the iron oxyhydroxide particles. The FTIR spectra of the δ-FeOOH/PMMA nanocomposites showed that the silane monomers were covalently attached to the δ-FeOOH particles. Because of the strong interaction between the PMMA and δ-FeOOH nanoparticles, the thermal stability of the δ-FeOOH/PMMA nanocomposites was improved compared to the pure PMMA. The SEM analysis conferred the size agglomerate of particles regarding the morphology of samples. The theoretical study enabled a better understanding of the interaction of the polymer with the iron oxyhydroxide. The DFT-based calculations reinforce the radical trapping mechanism of stabilization of nanocomposites; that is, Fe3+ species might be able to accept electrons coming from the organic phase that decomposes via radical unzipping. The radical scavenge effect delays the weight loss of polymer.

  16. NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 4. NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and DFT based theoretical studies on the adsorption behaviour of (S)-Phenylsuccinic acid on silver nanoparticles. D Sajan V Bena Jothy Thomas Kuruvilla I Hubert Joe. Full Papers Volume ...

  17. Acidic and Catalytic Properties of Mo-MCM-22 in Methane Aromatization: An FTIR Study

    Czech Academy of Sciences Publication Activity Database

    Sobalík, Zdeněk; Tvarůžková, Zdenka; Wichterlová, Blanka; Fíla, V.; Špatenka, Š.

    2003-01-01

    Roč. 253, - (2003), s. 271-282 ISSN 0926-860X R&D Projects: GA ČR GA104/99/0432 Institutional research plan: CEZ:AV0Z4040901 Keywords : methane aromatization * FTIR technique * MCM-22 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.825, year: 2003

  18. Interaction of procyanidin B-3 with membrane lipids Fluorescence, DSC and FTIR studies

    Czech Academy of Sciences Publication Activity Database

    Cyboran-Mikolajczyk, S.; Zylka, R.; Jurkiewicz, Piotr; Pruchnik, H.; Oszmianski, J.; Hof, M.; Kleszczynska, H.

    2017-01-01

    Roč. 1859, č. 8 (2017), s. 1362-1371 ISSN 0005-2736 Institutional support: RVO:61388955 Keywords : FTIR * Fluidity * Hydration * dmpc Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.498, year: 2016

  19. Interaction of procyanidin B-3 with membrane lipids Fluorescence, DSC and FTIR studies

    Czech Academy of Sciences Publication Activity Database

    Cyboran-Mikolajczyk, S.; Zylka, R.; Jurkiewicz, Piotr; Pruchnik, H.; Oszmianski, J.; Hof, M.; Kleszczynska, H.

    Roč. 1859, č. 8 ( 2017 ), s. 1362-1371 ISSN 0005-2736 Institutional support: RVO:61388955 Keywords : FTIR * Fluidity * Hydration * dmpc Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.498, year: 2016

  20. Theoretical Physics Division

    International Nuclear Information System (INIS)

    This report is a survey of the studies done in the Theoretical Physics Division of the Nuclear Physics Institute; the subjects studied in theoretical nuclear physics were the few-nucleon problem, nuclear structure, nuclear reactions, weak interactions, intermediate energy and high energy physics. In this last field, the subjects studied were field theory, group theory, symmetry and strong interactions [fr

  1. Vibrational microspectroscopy of food. Raman vs. FT-IR

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; Løkke, Mette Marie; Micklander, Elisabeth

    2003-01-01

    FT-IR and Raman spectroscopy are complementary techniques for the study of molecular vibrations and structure. The combination with a microscope results in an analytical method that allows spatially resolved investigation of the chemical composition of heterogeneous foods and food ingredients...... to different heterogeneous food systems. FT-IR and Raman microspectroscopy were applied to a number of different problems related to food analysis: (1) in situ determination of starch and pectin in the potato cell, (2) in situ determination of the distribution of amygdalin in bitter almonds, (3......) the composition of blisters found on the surface of bread, (4) the microstructure of high-lysine barley and (5) the composition of white spots in the shell of frozen shrimps. (C) 2003 Elsevier Science Ltd. All rights reserved....

  2. Evaluating the accuracy of theoretical one-bond 13 C─13 C scalar couplings and their ability to predict structure in a natural product.

    Science.gov (United States)

    Powell, Jacob; Valenti, Domenic; Bobnar, Harley; Drain, Erika; Elliott, Blaine; Frank, Sydney; McCullough, Tyler; Moore, Sean; Kettring, Andrew; Iuliucci, Robbie; Harper, James K

    2017-11-01

    This study explores the feasibility of using a combination of experimental and theoretical 1-bond 13 C─ 13 C scalar couplings ( 1 J CC ) to establish structure in organic compounds, including unknowns. Historically, n J CC and n J CH studies have emphasized 2 and 3-bond couplings, yet 1 J CC couplings exhibit significantly larger variations. Moreover, recent improvements in experimental measurement and data processing methods have made 1 J CC data more available. Herein, an approach is evaluated in which a collection of theoretical structures is created from a partial nuclear magnetic resonance structural characterization. Computed 1 J CC values are compared to experimental data to identify candidates giving the best agreement. This process requires knowledge of the error in theoretical methods, thus the B3LYP, B3PW91, and PBE0 functionals are evaluated by comparing to 27 experimental values from INADEQUATE. Respective errors of ±1.2, ±3.8, and ±2.3 Hz are observed. An initial test of this methodology involves the natural product 5-methylmellein. In this case, only a single candidate matches experimental data with high statistical confidence. This analysis establishes the intramolecular hydrogen-bonding arrangement, ring heteroatom identity, and conformation at one position. This approach is then extended to hydroheptelidic acid, a natural product not fully characterized in prior studies. The experimental/theoretical approach proposed herein identifies a single best-fit structure from among 26 candidates and establishes, for the first time, 1 configuration and 3 conformations to complete the characterization. These results suggest that accurate and complete structural characterizations of many moderately sized organic structures (<800 Da) may be possible using only 1 J CC data. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Analysis of molecular structure, spectroscopic properties (FT-IR, micro-Raman and UV-vis) and quantum chemical calculations of free and ligand 2-thiopheneglyoxylic acid in metal halides (Cd, Co, Cu, Ni and Zn).

    Science.gov (United States)

    Gökce, Halil; Bahçeli, Semiha

    2013-12-01

    In this study, molecular geometries, experimental vibrational wavenumbers, electronic properties and quantum chemical calculations of 2-thiopheneglyoxylic acid molecule, (C6H4O3S), and its metal halides (Cd, Co, Cu, Ni and Zn) which are used as pharmacologic agents have been investigated experimentally by FT-IR, micro-Raman and UV-visible spectroscopies and elemental analysis. Meanwhile the vibrational calculations were verified by DFT/B3LYP method with 6-311++G(d,p) and LANL2DZ basis sets in the ground state, for free TPGA molecule and its metal halide complexes, respectively, for the first time. The calculated fundamental vibrational frequencies for the title compounds are in a good agreement with the experimental data. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. High-pressure structural behavior of the double perovskite Sr2CrReO6: an experimental and theoretical study

    DEFF Research Database (Denmark)

    Olsen, J.S.; Gerward, Leif; Vaitheeswaran, G.

    2009-01-01

    The high-pressure structural behavior of Sr2CrReO6 has been studied experimentally using synchrotron radiation and the diamond anvil cell and theoretically using density functional theory. The experimental zero-pressure bulk modulus is B0=1704GPa and the pressure derivative is B0'=4.71.0. These r......'=4.71.0. These results compare well with the calculated values 172.6GPa and 5.7. A pseudo-cubic unit cell can describe the crystal structure at low pressure, but the tetragonal structure becomes evident at high pressure....

  5. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: A combined experimental and theoretical study

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-01

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm-1 and 4000-50 cm-1, respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion-1 and anion-2 conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1sbnd C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed.

  6. Electronic structure of CuTPP and CuTPP(F) complexes: a combined experimental and theoretical study II.

    Science.gov (United States)

    Mangione, Giulia; Sambi, Mauro; Carlotto, Silvia; Vittadini, Andrea; Ligorio, Giovanni; Timpel, Melanie; Pasquali, Luca; Giglia, Angelo; Nardi, Marco Vittorio; Casarin, Maurizio

    2016-09-28

    The unoccupied electronic structure of thick films of tetraphenylporphyrin and tetrakis(pentafluorophenyl)porphyrin Cu(ii) complexes (hereafter, CuTPP and CuTPP(F)) deposited on Au(111) has been studied by combining the outcomes of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with those of spin-unrestricted time-dependent density functional (TD-DFT) calculations carried out either within the scalar relativistic zeroth order regular approximation (ZORA) framework (C, N and F K-edges) or by using the Tamm-Dancoff approximation coupled to ZORA and including spin-orbit effects (Cu L2,3-edges). Similarly to the modelling of NEXAFS outcomes pertaining to other Cu(ii) complexes, the agreement between theory and experiment is more than satisfactory, thus confirming the open-shell TD-DFT to be a useful tool to look into NEXAFS results pertinent to Cu(ii) compounds. The combined effect of metalation and phenyl (Ph) fluorine decoration is found to favour an extensive mixing between (Ph)σ* and pristine porphyrin macrocyle (pmc) (pmc)π* virtual levels. The lowest lying excitation in the C and N K-edge spectra of both CuTPP and CuTPP(F) is associated with a ligand-to-metal-charge-transfer transition, unambiguously revealed in the (CuTPP)N K-edge spectral pattern. Moreover, the comparison with literature data pertaining to the modelling of the (Cu(II))L2,3 features in the phthalocyanine-Cu(ii) (CuPc) complex provided further insights into how metal-to-ligand-charge-transfer transitions associated with excitations from 2p(Cu(II)) AOs to low-lying, ligand-based π* MOs may contribute to the Cu(ii) L2,3-edge intensity and thus weaken its believed relationship with the Cu(ii)-ligand symmetry-restricted covalency. Despite the coordinative pocket of CuTPP/CuTPP(F) mirroring CuPc, the ligand-field strength exerted by the phthalocyanine ligand on the Cu(ii) centre is experimentally found and theoretically confirmed to be slightly stronger than that experienced by Cu

  7. Theoretical physics division

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    Research activities of the theoretical physics division for 1979 are described. Short summaries are given of specific research work in the following fields: nuclear structure, nuclear reactions, intermediate energy physics, elementary particles [fr

  8. Theoretical physics division

    International Nuclear Information System (INIS)

    Anon.

    The studies in 1977 are reviewed. In theoretical nuclear physics: nuclear structure, nuclear reactions, intermediate energy physics; in elementary particle physics: field theory, strong interactions dynamics, nucleon-nucleon interactions, new particles, current algebra, symmetries and quarks are studied [fr

  9. TG-FTIR analysis of biomass pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Bassilakis, R.; Carangelo, R.M.; Wojtowicz, M.A. [Advanced Fuel Research Inc., Hartford, CT (United States)

    2001-10-09

    A great need exists for comprehensive biomass-pyrolysis models that could predict yields and evolution patterns of selected volatile products as a function of feedstock characteristics and process conditions. A thermogravimetric analyzer coupled with Fourier transform infrared analysis of evolving products (TG-FTIR) can provide useful input to such models in the form of kinetic information obtained under low heating rate conditions. In this work, robust TG-FTIR quantification routes were developed for infrared analysis of volatile products relevant to biomass pyrolysis. The analysis was applied to wheat straw, three types of tobacco (Burley, Oriental, and Bright) and three biomass model compounds (xylan, chlorogenic acid, and D-glucose). Product yields were compared with literature data, and species potentially quantifiable by FT-IR are reviewed. Product-evolution patterns are reported for all seven biomass samples. 41 refs., 7 figs., 2 tabs.

  10. Accurate theoretical determination of the structure of aromatic complexes is complicated: the phenol dimer and phenol...methanol cases

    Czech Academy of Sciences Publication Activity Database

    Kolář, Michal; Hobza, Pavel

    2007-01-01

    Roč. 111, č. 26 (2007), s. 5851-5854 ISSN 1089-5639 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550510 Institutional research plan: CEZ:AV0Z40550506 Keywords : phenol dimer * dispersion energy * molecular cluster Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.918, year: 2007

  11. Theoretical study of the errors in the magnetic structure in the SSC's at GANIL. Determination of tolerances

    International Nuclear Information System (INIS)

    Chabert, A.; Gendreau, G.

    A study was made of the magnetic field tolerances allowable in the separated sector cyclotrons (Cyclotron a Secteurs Separees or CSS) at GANIL (Grand Accelerateur National a Ions Lourdes). The presentation includes: a theoretical review; SSC characteristics; and a study of errors in the topography of the field for the accelerated orbit

  12. Theoretical studies of the active-site structure, spectroscopic and thermodynamic properties, and reaction mechanism of multicopper oxidases

    Czech Academy of Sciences Publication Activity Database

    Rulíšek, Lubomír; Ryde, U.

    2013-01-01

    Roč. 257, č. 2 (2013), s. 445-458 ISSN 0010-8545 Institutional support: RVO:61388963 Keywords : multi-copper oxidases * QM/MM calculations * multireference calculations * theoretical spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 12.098, year: 2013

  13. Experimental and theoretical study of the electronic and magnetic structures of Mn1-xCr xAu2

    International Nuclear Information System (INIS)

    Hsu, L.-S.; Murakawa, T.; Fujiwara, H.; Sekiyama, A.; Suga, S.; Imada, S.; Yano, M.; Miyamachi, T.; Higashimichi, H.; Yamaguchi, J.; Funabashi, G.; Yabashi, M.; Ishikawa, T.; Higashiya, A.

    2007-01-01

    X-ray photoemission spectra of Mn 1-x Cr x Au 2 (x = 0, 0.05, and 0.13) are presented and compared with theoretical total and partial density of state (DOS) curves. Site- and spin-decomposed partial DOS and magnetism of these materials are also discussed

  14. Spectroscopic characterization of bioactive Cu(II complexes with polysaccharides by modern FTIR microspectroscopy

    Directory of Open Access Journals (Sweden)

    Mitić Žarko

    2010-01-01

    Full Text Available Investigations of bioactive copper complexes are of great interest for the pharmaceutical industry from the aspect of therapy of hypochromic microcitary anemia and hypocupremia. The structure of bioactive copper complexes with oligosaccharides has not yet been explained in details despite a number of studies. This work represents further development in the research of the complex structure and pharmacobiological activity of the copper complexes. Different copper complexes with dextran and pullulan oligosaccharides, as well as reduced derivatives, have been analyzed by IR spectroscopy. Characterization of the complexes has been performed by using modern spectroscopic techniques: RT-FTIR, LNT-FTIR, D2O-FTIR, ATR-FTIR and FTIR microspectroscopy. Results of FTIR microspectroscopic investigations show that the structural form of complexes and copper content depend considerably on constitution and ligands conformation, degree of crystallinity, polymerization, polydispersity, and linearity of macromolecules. Also, stability of the synthesized complexes, as well as their pharmacological effect, depend on these parameters. Based on IR testing results, structures of the synthesized Cu(II complexes with polysaccharides were confirmed.

  15. Experimental and theoretical investigation of the molecular, electronic structure and solvatochromism of phenyl salicylate: External electric field effect on the electronic structure

    Science.gov (United States)

    Sıdır, İsa; Sıdır, Yadigar Gülseven

    2017-11-01

    The UV-vis absorption and steady state fluorescence spectra of phenyl salicylate (abbreviated as PS) have been recorded in a series of non-polar, polar protic and polar aprotic solvents at room temperature and the obtained spectral data are used to determine the solvatochromic behavior and the ground and excited state dipole moments. Basis set sensitive molecular structure along with X-ray crystal data are evaluated. The ground state and excited state dipole moments are determined by using Lippert-Mataga, Bakhshiev, Bilot-Kawski and Reichardt solvatochromic shift methods as a function of dielectric constant (ε) and refractive index (n) of the solvents. The larger excited state dipole moment value indicates the more polar PS in the excited state. The rate of μe/μg is found as 2.4239. Solvatochromic behavior of PS is enlightened by using Kamlet-Taft and Catalan models. Kamlet-Taft solvatochromic model indicates that non-specific solute solvent interactions are controlled by solvent dispersion-induction forces and specific interactions are directed by hydrogen-bond donor capacity of solvent. Catalan solvatochromic model designates that solute-solvent interactions are governed by solvent polarizability. Ground and excited state dipole moments are found theoretically by using DFT/B3LYP/6-311++G(d, p) and TDDFT/B3LYP/6-31++G(d, p) methods. External electric field effect on LUMO-HOMO band gap and dipole moment have been investigated by using B3LYP/6-311++G(d, p) method.

  16. Theoretical study of structure, pKa, lipophilicity, solubility, absorption, and polar surface area of some centrally acting antihypertensives.

    Science.gov (United States)

    Remko, Milan; Swart, Marcel; Bickelhaupt, F Matthias

    2006-03-15

    The methods of theoretical chemistry have been used to elucidate the molecular properties of the substituted imidazoline and oxazoline structures, a class of potent agonists and antagonists of imidazoline receptors. The geometries of various tautomers and isomers of 2-[2,6-dichlorophenylimino]imidazolidine (clonidine), 1-(N-dicyclopropylmethyl)amino-2-oxazoline (rilmenidine), 4-chloro-N-(4,5-dihydro-1H-imidazol-2yl)-6-methoxy-2-methyl-5-pyrimidinamine (moxonidine), N-(dicyclopropylmethyl)-4,5-dihydro-1H-pyrrol-2-amine (aminopyrroline), N-dicyclopropylmethyl-4,5-dihydrothiazol-2-amine (aminothiazoline), 4,5-dihydro-2-(2-methoxyphenyl)-1H-imidazole (compound_6), 4,5-dihydro-2-(3-methylthiophen-2-yl)-1H-imidazole (compound_7), N-(2-chloro-4-iodophenyl)-4,5-dihydro-5-methyl-3H-pyrrol-2-amine (LNP_911), N-amidino-3,5-diamino-6-chloropyrazine-carboxamide (amiloride), 2-(1,4-benzodioxan-2-yl)-2-imidazoline (idazoxan), (+/-)-2-(2-ethyl-2,3-dihydro-2-benzofuranyl)-2-imidazoline (efaroxan), (4-aminobutyl)guaninine (agmatine), and 1-methyl-9H-pyrido[3,4-b]indole (harmane) have been studied using Becke3LYP/6-31+G(d,p) and BP86/TZ2P DFT methods. The optimized geometries indicate that these molecules show a distinctly nonplanar configuration of the imidazoline and oxazoline moieties. In the gas-phase, rilmenidine and aminothiazoline exist in two forms (amino and imino), the amino tautomers being more stable by about 6 kJ/mol. The calculations showed, in agreement with experiments, that clonidine, moxonidine, and LNP_911 exist in a more stable imino tautomer. The tautomer containing the amino group is by about 30 kJ/mol less stable. Computations that include the effect of solvation indicated that also in water the relative stability order of individual tautomers (amino and imino forms) is preserved. The computed pKa values varied between 6.7 and 9.0, and correlate well with the available experimental pKa's found in the literature. Among the clinically useful antihypertensives

  17. Biochemical applications of FT-IR spectroscopy

    NARCIS (Netherlands)

    Pistorius, A.M.A.

    1996-01-01

    This thesis describes the use of (FT-)IR spectroscopy in general biochemical research. In chapter 3, IR spectroscopy is used in the quantitation of residual detergent after reconstitution of an integral membrane protein in a pre-defined lipid matrix. This chapter discusses the choice of the

  18. Pressure induced structural changes in the potential hydrogen storage compound ammonia borane: A combined X-ray, neutron and theoretical investigation

    International Nuclear Information System (INIS)

    Kumar, Ravhi S.; Ke, Xuezhi; Zhang, Jianzhong; Lin, Zhijun; Vogel, Sven C.; Hartl, Monika; Sinogeikin, Stanislav; Daemen, Luke; Cornelius, Andrew L.; Chen, Changfeng; Zhao, Yusheng

    2010-01-01

    The crystal structure of NH 3 BH 3 was investigated using synchrotron high pressure X-ray diffraction (HPXRD) up to 27 GPa and neutron diffraction up to 5 GPa. Density functional theoretical (DFT) calculations were carried out simultaneously for comparison. The results confirm a pressure induced phase transition from the tetragonal I4mm phase to a high pressure orthorhombic Cmc21 phase around 1.22 GPa. Further increase of pressure above 8 GPa, we observed a second structural transition from Cmc21 to a triclinic P1 phase which are reversible with small hysteresis. The transition pressures and the bulk modulus obtained experimentally are in good agreement with theory.

  19. Theoretical study of the structures and electron affinities of the dimers and trimers of the group IB metals (Cu, Ag, and Au)

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

    1989-01-01

    The molecular structure of both the neutral and negatively charged diatomic and triatomic systems containing the Cu, Ag, and Au metals are determined from ab initio calculations. For the neutral triatomic systems, the lowest energy structure is found to be triangular. The relative stability of the 2A1 and 2B2 structures can be predicted simply by knowing the constituent diatomic bond distances and atomic electron affinities (EAs). The lowest energy structure is linear for all of the negative ions. For anionic clusters containing Au, the Au atom(s) preferentially occupy the terminal position(s). The EAs of the heteronuclear systems can be predicted relatively accurately from a weighted average of the corresponding homonuclear systems. Although the theoretical EAs are systematically too small, accurate predictions for the EAs of the triatomics are obtained by uniformly scaling the ab initio results using the accurate experimental EA values available for the atoms and homonuclear diatomics.

  20. Fish stock assessment under data limitations developing a new method based on a size-structured theoretical ecology framework

    DEFF Research Database (Denmark)

    Kokkalis, Alexandros

    -series. The method provides estimates of fishing mortality and the FMSY reference point, it is tested and validated, and is implemented as software package making it easy to use by stakeholders of different levels. The basis of the method is a size-based theoretical ecology framework that describes exploited fish...... catch is known, important quantities about the stock (e.g. biomass of spawners, recruitment) can be quantified. The method is tested using simulated data and validated using a subset of available data from data-rich fish stocks. The implementation of the method as a software package in the R programming...

  1. Theoretical study on the electronic structures and phosphorescent properties of a series of iridium(III) complexes with the different positional N-substitution in the pyridyl moiety

    Energy Technology Data Exchange (ETDEWEB)

    Han, Deming; Hao, Fengqi [School of Life Science and Technology, Changchun University of Science and Technology, Changchun 130022 (China); Tian, Jian [Clean Energy Technology Laboratory, Changchun University of Science and Technology, Changchun 130022 (China); Pang, Chunying; Li, Jingmei [School of Life Science and Technology, Changchun University of Science and Technology, Changchun 130022 (China); Zhao, Lihui, E-mail: zhaolihui@yahoo.com [School of Life Science and Technology, Changchun University of Science and Technology, Changchun 130022 (China); Zhang, Gang [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China)

    2015-03-15

    The geometry structures, electronic structures, absorption and phosphorescent properties of a series of iridium(III) complexes with the different N-substitution cyclometalating ligand and the same benzyldiphenylphosphine auxiliary ligand have been theoretically investigated by using the density functional theory method. The lowest energy absorption wavelengths are located at 378 nm for A, 430 nm for B, 411 nm for C, 436 nm for D, and 394 nm for E. The introduction of N atom substitution at 1-, 2-, 3-, and 4-positions on the pyridyl moiety of complex A leads to an obvious redshifted absorption. The lowest energy emissions for complexes A–E are localized at 450, 409, 438, 483, and 429 nm, respectively, simulated in CH{sub 2}Cl{sub 2} medium at M052X level. Ionization potential and electron affinity have been calculated to evaluate the injection abilities of holes and electrons into these complexes. For complex C, the calculated results showed that it can possibly possess the larger radiative decay rate (k{sub r}) value than those of other four complexes. It is anticipated that the theoretical studies can provide valuable information for designing new phosphorescent metal complexes of organic light-emitting diodes. - Highlights: • Five Ir(III) complexes have been theoretically investigated. • The effect of N-substitution cyclometalating ligand has been studied. • The complex C possibly possesses the largest radiative decay rate value.

  2. How Anion Chaotrope Changes the Local Structure of Water. Insights from Photoelectron Spectroscopy and Theoretical Modeling of SCN- Water Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Valiev, Marat [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Shihu [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Xue B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-09

    The behavior of charged solute molecules in aqueous solutions is often classified using the concept of kosmotropes (“structure makers”) and chaotropes (“structure breakers”). There is a growing consensus that the key to kosmotropic/chaotropic behaviors lies in the local solvent region, but the exact microscopic basis for such differentiation is not well understood. This issue is examined in this work by analyzing size selective solvation of a well-known chaotrope, negatively charged SCN- molecule. Combining experimental photoelectron spectroscopy measurements with theoretical modeling we examine evolution of solvation structure up to eight waters. We observe that SCN- indeed fits the description of weakly hydrated ion and its solvation is heavily driven by stabilization of water-water interaction network. However, the impact on water structure is more subtle than that associated with “structure breaker”. In particular, we observe that the solvation structure of SCN- preserves the “packing” structure of the water network but changes local directionality of hydrogen bonds in the local solvent region. The resulting effect closer to that of “structure weakener”, where solute can be readily accommodated into the native water network, at the cost of compromising its stability due to constraints on hydrogen bonding.

  3. Advances in handheld FT-IR instrumentation

    Science.gov (United States)

    Arnó, Josep; Cardillo, Len; Judge, Kevin; Frayer, Maxim; Frunzi, Michael; Hetherington, Paul; Levy, Dustin; Oberndorfer, Kyle; Perec, Walter; Sauer, Terry; Stein, John; Zuidema, Eric

    2012-06-01

    FT-IR spectroscopy is the technology of choice to identify solid and liquid phase unknown samples. The challenges of ConOps (Concepts of Operation) in emergency response and military field applications require a significant redesign of the stationary FT-IR bench-top instruments typically used in laboratories. Specifically, field portable units require high levels of resistance against mechanical shock and chemical attack, ease of use in restrictive gear, quick and easy interpretation of results, and reduced size. In the last 20 years, FT-IR instruments have been re-engineered to fit in small suitcases for field portable use and recently further miniaturized for handheld operation. This article introduces the advances resulting from a project designed to overcome the challenges associated with miniaturizing FT-IR instruments. The project team developed a disturbance-corrected permanently aligned cube corner interferometer for improved robustness and optimized opto-mechanical design to maximize optical throughput and signal-to-noise ratios. Thermal management and heat flow were thoroughly modeled and studied to isolate sensitive components from heat sources and provide the widest temperature operation range. Similarly, extensive research on mechanical designs and compensation techniques to protect against shock and vibration will be discussed. A user interface was carefully created for military and emergency response applications to provide actionable information in a visual, intuitive format. Similar to the HazMatID family of products, state-of-the-art algorithms were used to quickly identify the chemical composition of complex samples based on the spectral information. This article includes an overview of the design considerations, tests results, and performance validation of the mechanical ruggedness, spectral, and thermal performance.

  4. Theoretical analysis of wave dispersion in the slow-wave structure such as a coaxial ribbed line

    Science.gov (United States)

    Yelizarov, A. A.; Pchelnikov, Yu. N.; Shaymardanov, R. V.

    2017-08-01

    The wave dispersion in the slow-wave structure such as a coaxial ribbed line has been analyzed. For the case of the excitation of an axially symmetric wave in this structure, the generalized dispersion equation has been obtained using the method of sewing the conductivities. The particular cases of a solution of the dispersion equation have been analyzed, as well as its solutions for relatively high and low frequencies, since these cases are of practical interest. The parameters of a coaxial ribbed line have been simulated and the dependences of the slowing coefficient and the wave impedance of the structure on its geometrical dimensions have been obtained.

  5. Theoretical study of the structure and optical properties of rare-earth-doped BeF2 glass

    International Nuclear Information System (INIS)

    Brawer, S.; Weber, M.J.

    1980-01-01

    We investigate the question of whether the local structure of a glass can be deduced directly from its optical spectra by testing such a procedure on a model system. The model system was Eu 3+ -doped BeF 2 glass generated the Monte Carlo technique of statistical mechanics. The optical energy levels of Eu 3+ were calculated from a point charge model. Using the resulting spectra as data, it is shown that details of the structure of the rare-earth ion sites of the simulated glass cannot be reconstructed uniquely from the data. Based on these results, it is concluded that reliable glass structure cannot be deduced from optical spectra

  6. Theoretical investigation of five-layer waveguide structure including two left-handed material layers for refractometric applications

    Science.gov (United States)

    Alkanoo, Anas A.; Taya, Sofyan A.

    2018-03-01

    A slab waveguide structure consisting of five layers is studied for optical sensing applications. The five-layer waveguide structure has a guiding dielectric film, two left-handed material (LHM) layers and two dielectric layers as a substrate and a cladding. The dispersion relation and the sensitivity to any change in the index of the analyte layer are derived. The sensitivity is explored with different parameters of the structure. It is found that the sensitivity of the proposed structure can be significantly improved with the increase of the index of the guiding layer and the decrease of the permittivity of the LHM layers. Moreover, it can be also improved with the increase of the thickness of the LHM layers.

  7. Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin.

    Science.gov (United States)

    Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

    2007-09-01

    The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier.

  8. Small-Pore Molecular Sieves SAPO-34 with Chabazite Structure: Theoretical Study of Silicon Incorporation and Interrelated Catalytic Activity

    Science.gov (United States)

    Wang, Hong; Lewis, James; Liu, Zhongmin

    2011-03-01

    The catalytic conversion of methonal to olefin (MTO) has attracted attention both in industrial and academic fields. Strong evidence shows that small-pore molecular sieves with certain amount silicon incorporated (SAPO) present promising high catalytic activity in MTO conversion. Using DFT, we study the structural and electronic properties of chabazite SAPO-34. Although there are extensively experimental results show that silicon incorporation does not change the overall structure as the original AlPO structure, local structural changes are still created by silicon substitution, which probably accounted for the high catalytic activity. It is noted that the catalytic activity of SAPO-34 presents increasing trend along with the silicon incorporation amount increasing and maintain a flat peak even with more silicon incorporated. Hence, there is an optimal silicon incorporation amount which possibly yields the highest catalytic MTO conversion.

  9. DEVELOPING MEASURES TO IMPROVE STRENGTH INDICES OF SUPPORTING STRUCTURES FOR HEAD CARS OF DIESEL TRAINS DR1A ON THE BASIS OF EXPERIMENTAL-AND-THEORETICAL WORKS

    Directory of Open Access Journals (Sweden)

    O. M. Bondarev

    2014-11-01

    Full Text Available Purpose. The objective is to determine the stress-strain state of supporting structures of the head car body and the traction transmission unit, which can be created in the operation of emergency situations, and to develop the measures aimed at improving the stress-strain state of these elements. Methodology. In order to achieve this objective, in performing the work an experimental determination of efforts and stress levels in the most loaded elements of supporting structures as well as the traction transmission units was conducted; design models for the theoretical determination of stress and effort levels were developed. Findings. Based on the analysis of the calculation results the best options for the upgrades, which have been put into the basis of proposals aimed at improving the strength indices, were revealed. Originality. Based on the experimental and theoretical studies, scientific monitoring of development works on modernization and improvement of strength indices of supporting structures of head cars of diesel trains DR1A was performed. Practical value. The technical solution to the measures, which are to be carried out beyond the limits of assigned operation lifetime for diesel train of the series specified was developed and transferred to the Ukrzaliznytsia experts to introduce the proposed measures on improving the strength indices.

  10. Experimental and Theoretical Investigations on the Supermolecular Structure of Isoliquiritigenin and 6-O-α-D-Maltosyl-β-cyclodextrin Inclusion Complex

    Directory of Open Access Journals (Sweden)

    Bin Li

    2015-08-01

    Full Text Available Isoliquiritigenin (ILTG possesses many pharmacological properties. However, its poor solubility and stability in water hinders its wide applications. The solubility of bioactive compounds can often be enhanced through preparation and delivery of various cyclodextrin (CD inclusion complexes. The 6-O-α-D-maltosyl-β-CD (G2-β-CD, as one of the newest developments of CDs, has high aqueous solubility and low toxicity, especially stable inclusion characteristics with bioactive compounds. In this work, we for the first time construct and characterize the supermolecular structure of ILTG/G2-β-CD by scanning electron microscopy (SEM, ultraviolet-visible spectroscopy (UV, Fourier transform infrared spectroscopy (FT-IR, and X-ray diffractometry (XRD. The solubility of ILTG in water at 25 °C rises from 0.003 to 0.717 mg/mL by the encapsulation with G2-β-CD. Our experimental observations on the presence of the ILTG/G2-β-CD inclusion complex are further supported by the ONIOM(our Own N-layer Integrated Orbital molecular Mechanics-based QM/MM (Quantum Mechanics/Molecular Mechanics calculations, typically substantiating these supermolecular characteristics, such as detailed structural assignments, preferred binding orientations, selectivity, solvent effects, interaction energies and forces of the ILTG/G2-β-CD inclusion complex. Our results have elucidated how ILTG interacts with G2-β-CD, demonstrating the primary host-guest interactions between ILTG and G2-β-CD, characterized by hydrogen bonds, hydrophobic interactions, electrostatic forces, and conformational effects, are favored for the formation of the ILTG/G2-β-CD inclusion.

  11. Effective L/D: A Theoretical Approach to the Measurement of Aero-Structural Efficiency in Aircraft Design

    Science.gov (United States)

    Guynn, Mark D.

    2015-01-01

    There are many trade-offs in aircraft design that ultimately impact the overall performance and characteristics of the final design. One well recognized and well understood trade-off is that of wing weight and aerodynamic efficiency. Higher aerodynamic efficiency can be obtained by increasing wing span, usually at the expense of higher wing weight. The proper balance of these two competing factors depends on the objectives of the design. For example, aerodynamic efficiency is preeminent for sailplanes and long slender wings result. Although the wing weight-drag trade is universally recognized, aerodynamic efficiency and structural efficiency are not usually considered in combination. This paper discusses the concept of "aero-structural efficiency," which combines weight and drag characteristics. A metric to quantify aero-structural efficiency, termed effective L/D, is then derived and tested with various scenarios. Effective L/D is found to be a practical and robust means to simultaneously characterize aerodynamic and structural efficiency in the context of aircraft design. The primary value of the effective L/D metric is as a means to better communicate the combined system level impacts of drag and structural weight.

  12. Structure-activity relationships for novel drug precursor N-substituted-6-acylbenzothiazolon derivatives: A theoretical approach

    Science.gov (United States)

    Sıdır, Yadigar Gülseven; Sıdır, İsa

    2013-08-01

    In this study, the twelve new modeled N-substituted-6-acylbenzothiazolon derivatives having analgesic analog structure have been investigated by quantum chemical methods using a lot of electronic parameters and structure-activity properties; such as molecular polarizability (α), dipole moment (μ), EHOMO, ELUMO, q-, qH+, molecular volume (Vm), ionization potential (IP), electron affinity (EA), electronegativity (χ), molecular hardness (η), molecular softness (S), electrophilic index (ω), heat of formation (HOF), molar refractivity (MR), octanol-water partition coefficient (log P), thermochemical properties (entropy (S), capacity of heat (Cv)); as to investigate activity relationships with molecular structure. The correlations of log P with Vm, MR, ω, EA, EHOMO - ELUMO (ΔE), HOF in aqueous phase, χ, μ, S, η parameters, respectively are obtained, while the linear relation of log P with IP, Cv, HOF in gas phase are not observed. The log P parameter is obtained to be depending on different properties of compounds due to their complexity.

  13. Effect of structural changes in sesquifulvalene on the intramolecular charge transfer and nonlinear polarizations a theoretical study

    Science.gov (United States)

    Nandi, P. K.; Mandal, K.; Kar, T.

    2003-11-01

    Ab initio HF calculations of the ground state structural parameters, and the time dependent HF (TDHF) calculations of static nonlinear polarizabilities have been performed for a number of sesquifulvalene derivatives. The calculated NLO parameters show a good correlation with the hardness parameters. The nature of hetero-atoms and their positions can strongly influence the intramolecular charge transfer (ICT) interactions and the nonlinear polarizations of sesquifulvalene. Nonlinear polarizabilities in the twisted structures have been found to depend both on the energy barrier to twist and the transition energy corresponding to the twisted ICT (TICT) state characterized by the HOMO → LUMO transition.

  14. Probing Chemical Bonding and Electronic Structures in ThO-by Anion Photoelectron Imaging and Theoretical Calculations.

    Science.gov (United States)

    Li, Yanli; Zou, Jinghan; Xiong, Xiao-Gen; Su, Jing; Xie, Hua; Fei, Zejie; Tang, Zichao; Liu, Hongtao

    2017-03-16

    Because of renewed research on thorium-based molten salt reactors, there is growing demand and interest in enhancing the knowledge of thorium chemistry both experimentally and theoretically. Compared with uranium, thorium has few chemical studies reported up to the present. Here we report the vibrationally resolved photoelectron imaging of the thorium monoxide anion. The electron affinity of ThO is first reported to be 0.707 ± 0.020 eV. Vibrational frequencies of the ThO molecule and its anion are determined from Franck-Condon simulation. Spectroscopic evidence is obtained for the two-electron transition in ThO - , indicating the strong electron correlation among the (7s σ ) 2 (6d δ ) 1 electrons in ThO - and the (7s σ ) 2 electrons in ThO. These findings are explained by using quantum-chemical calculations including spin-orbit coupling, and the chemical bonding of gaseous ThO molecules is analyzed. The present work will enrich our understanding of bonding capacities with the 6d valence shell.

  15. Theoretical assessment of optical resolution enhancement and background fluorescence reduction by three-dimensional nonlinear structured illumination microscopy using stimulated emission depletion

    Science.gov (United States)

    Dake, Fumihiro

    2016-08-01

    Three-dimensional structured illumination microscopy (SIM) enlarges frequency cutoff laterally and axially by a factor of two, compared with conventional microscopy. However, its optical resolution is still fundamentally limited. It is necessary to introduce nonlinearity to enlarge frequency cutoff further. We propose three-dimensional nonlinear structured illumination microscopy based on stimulated emission depletion (STED) effect, which has a structured excitation pattern and a structured STED pattern, and both three-dimensional illumination patterns have the same lateral pitch and orientation. Theoretical analysis showed that nonlinearity induced by STED effect, which causes harmonics and contributes to enlarging frequency cutoff, depends on the phase difference between two structured illuminations and that the phase difference of π is the most efficient to increase nonlinearity. We also found that undesirable background fluorescence, which degenerates the contrast of structured pattern and limits the ability of SIM, can be reduced by our method. These results revealed that optical resolution improvement and background fluorescence reduction would be compatible. The feasibility study showed that our method will be realized with commercially available laser, having 3.5 times larger frequency cutoff compared with conventional microscopy.

  16. Molecular basis of protein structure in proanthocyanidin and anthocyanin-enhanced Lc-transgenic alfalfa in relation to nutritive value using synchrotron-radiation FTIR microspectroscopy: A novel approach

    Science.gov (United States)

    Yu, Peiqiang; Jonker, Arjan; Gruber, Margaret

    2009-09-01

    To date there has been very little application of synchrotron radiation-based Fourier transform infrared microspectroscopy (SRFTIRM) to the study of molecular structures in plant forage in relation to livestock digestive behavior and nutrient availability. Protein inherent structure, among other factors such as protein matrix, affects nutritive quality, fermentation and degradation behavior in both humans and animals. The relative percentage of protein secondary structure influences protein value. A high percentage of β-sheets usually reduce the access of gastrointestinal digestive enzymes to the protein. Reduced accessibility results in poor digestibility and as a result, low protein value. The objective of this study was to use SRFTIRM to compare protein molecular structure of alfalfa plant tissues transformed with the maize Lc regulatory gene with non-transgenic alfalfa protein within cellular and subcellular dimensions and to quantify protein inherent structure profiles using Gaussian and Lorentzian methods of multi-component peak modeling. Protein molecular structure revealed by this method included α-helices, β-sheets and other structures such as β-turns and random coils. Hierarchical cluster analysis and principal component analysis of the synchrotron data, as well as accurate spectral analysis based on curve fitting, showed that transgenic alfalfa contained a relatively lower ( P protein displayed no difference ( P > 0.05) in the ratio of α-helices to β-sheets (average: 1.4) and higher ( P protein. The transgenic protein structures also exhibited no difference ( P > 0.05) in the vibrational intensity of protein amide I (average of 24) and amide II areas (average of 10) and their ratio (average of 2.4) compared with non-transgenic alfalfa. Cluster analysis and principal component analysis showed no significant differences between the two genotypes in the broad molecular fingerprint region, amides I and II regions, and the carbohydrate molecular region

  17. Theoretical prediction of new C-Si alloys in {\\boldsymbol{C}}2/{\\boldsymbol{m}}-20 structure

    Science.gov (United States)

    Xu, Xiangyang; Chai, Changchun; Fan, Qingyang; Yang, Yintang

    2017-04-01

    We study structural, mechanical, and electronic properties of C20, Si20 and their alloys (C16Si4, C12Si8, C8Si12, and C4 {{Si}}16) in C2/m structure by using density functional theory (DFT) based on first-principles calculations. The obtained elastic constants and the phonon spectra reveal mechanical and dynamic stability. The calculated formation enthalpy shows that the C-Si alloys might exist at a specified high temperature scale. The ratio of B/G and Poisson’s ratio indicate that these C-Si alloys in C2/m-20 structure are all brittle. The elastic anisotropic properties derived by bulk modulus and shear modulus show slight anisotropy. In addition, the band structures and density of states are also depicted, which reveal that C20, C16Si4, and Si20 are indirect band gap semiconductors, while C8Si12 and C4Si16 are semi-metallic alloys. Notably, a direct band gap semiconductor (C12Si8) is obtained by doping two indirect band gap semiconductors (C20 and Si20). Project supported by the National Natural Science Foundation of China (Grant No. 61474089) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (Grant No. 2015-0214.XY.K).

  18. Toward a Theoretical Model of Dispositional Influences on Transfer of Learning: A Test of a Structural Model

    Science.gov (United States)

    Yamkovenko, Bogdan; Holton, Ed

    2010-01-01

    This study explores the hypothesized relationship between dimensions of the Five Factor model of personality, goal orientation, self-efficacy, and intent to transfer training on the job. This study attempts to model the complex relationship between these characteristics and intent to transfer using structural equation modeling approach. A set of…

  19. Composition dependent multiple structural transformations of myoglobin in aqueous ethanol solution: A combined experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, R.; Samajdar, R. N.; Bhattacharyya, Aninda Jiban; Bagchi, B., E-mail: bbagchi@sscu.iisc.ernet.in [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India)

    2015-07-07

    Experimental studies (circular dichroism and ultra-violet (UV) absorption spectra) and large scale atomistic molecular dynamics simulations (accompanied by order parameter analyses) are combined to establish a number of remarkable (and unforeseen) structural transformations of protein myoglobin in aqueous ethanol mixture at various ethanol concentrations. The following results are particularly striking. (1) Two well-defined structural regimes, one at x{sub EtOH} ∼ 0.05 and the other at x{sub EtOH} ∼ 0.25, characterized by formation of distinct partially folded conformations and separated by a unique partially unfolded intermediate state at x{sub EtOH} ∼ 0.15, are identified. (2) Existence of non-monotonic composition dependence of (i) radius of gyration, (ii) long range contact order, (iii) residue specific solvent accessible surface area of tryptophan, and (iv) circular dichroism spectra and UV-absorption peaks are observed. Interestingly at x{sub EtOH} ∼ 0.15, time averaged value of the contact order parameter of the protein reaches a minimum, implying that this conformational state can be identified as a molten globule state. Multiple structural transformations well known in water-ethanol binary mixture appear to have considerably stronger effects on conformation and dynamics of the protein. We compare the present results with studies in water-dimethyl sulfoxide mixture where also distinct structural transformations are observed along with variation of co-solvent composition.

  20. Synthesis, characterization, crystal structure and theoretical studies of new chiral Schiff base (E)-4-hydroxy[(1-phenylethyl)iminomethyl]benzyne

    Czech Academy of Sciences Publication Activity Database

    Khalaji, A.D.; Gholinejad, M.; Rad, S.M.; Grivani, G.; Fejfarová, Karla; Dušek, Michal

    2015-01-01

    Roč. 41, č. 3 (2015), 1635-1645 ISSN 0922-6168 R&D Projects: GA ČR(CZ) GC202/07/J007 Institutional support: RVO:68378271 Keywords : Schiff base * crystal structure * DFT calculation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.833, year: 2015

  1. Theoretical Study on the Second Hyperpolarizailities of Oligomeric Systems Composed of Carbon and Silicon π-Structures.

    Science.gov (United States)

    Matsui, Hiroshi; Nagami, Takanori; Takamuku, Shota; Ito, Soichi; Kitagawa, Yasutaka; Nakano, Masayoshi

    2016-11-15

    To explore the prospect of molecules involving silicon-silicon multiple bonds as nonlinear optical molecular systems, the relationship between the structure and the second hyperpolarizabilities γ of the oligomeric systems composed of carbon and silicon π-structures is investigated using the density functional theory method. It is found that these compounds indicate intramolecular charge transfer (ICT) from the silicon units to the carbon units together with nonzero diradical characters. The γ values of these compounds are shown to be 2-13 times as large as those of the carbon analogs. Although asymmetric carbon and silicon π-systems exhibit comparable enhancement to the corresponding symmetric systems, donor-π-donor structures exhibit remarkable enhancement of γ despite of their both-end short silicon π-chain moieties (donor units). Further analysis using the odd electron and γ densities clarifies that the intermediate diradical character also contributes to the enhancement of γ. These results predict that even short π-conjugated silicone moieties can cause remarkable enhancement of γ by introducing them into π-conjugated hydrocarbon structures.

  2. Synthesis, crystal structure analysis, spectral (NMR, FT-IR, FT-Raman and UV-Vis) investigations, molecular docking studies, antimicrobial studies and quantum chemical calculations of a novel 4-chloro-8-methoxyquinoline-2(1H)-one: An effective antimicrobial agent and an inhibition of DNA gyrase and lanosterol-14α-demethylase enzymes

    Science.gov (United States)

    Murugavel, S.; Sundramoorthy, S.; Lakshmanan, D.; Subashini, R.; Pavan Kumar, P.

    2017-03-01

    The novel title compound 4-chloro-8-methoxyquinoline-2(1H)-one (4CMOQ) has been synthesized by slow evaporation solution growth technique at room temperature. The synthesized 4CMOQ molecule was characterized experimentally by FT-IR, FT-Raman, UV-Vis, NMR and single crystal diffraction (XRD) and theoretically by quantum chemical calculations. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311++G (d,p) basis set in ground state and compared with the experimental data. The entire vibrational assignments of wave numbers were made on the basis of potential energy distribution (PED) by VEDA 4 programme. The nuclear magnetic resonance spectra (1H and 13C NMR) are obtained by using the gauge-invariant atomic orbital (GIAO) method. The change in electron density (ED) in the antibonding orbital's and stabilization energies E(2) of the molecule have been evaluated by natural bond orbital (NBO) analysis to give clear evidence of stabilization. Moreover, electronic characteristics such as HOMO and LUMO energies, Mulliken atomic charges and molecular electrostatic potential surface are investigated. Absorption spectrum analysis, nonlinear optical properties, chemical reactivity descriptors and thermodynamic features are also outlined theoretically. Molecular docking studies were executed to understand the inhibitory activity of 4CMOQ against DNA gyrase and Lanosterol 14 α-demethylase. The antimicrobial activity of 4CMOQ was determined against bacterial strains such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and fungal strains such as Aspergillus niger, Monascus purpureus and Penicillium citrinum. The obtained results show that the compound exhibited good to moderate antimicrobial activity.

  3. Molecular Basis of Protein Structure in Proanthocyanidin and Anthocyanin-Enhanced Lc-transgenic Alfalfa in Relation to Nutritive Value Using Synchrotron-Radiation FTIR Microspectroscopy: A Novel Approach

    International Nuclear Information System (INIS)

    Yu, P.; Jonker, A.; Gruber, M.

    2009-01-01

    To date there has been very little application of synchrotron radiation-based Fourier transform infrared microspectroscopy (SRFTIRM) to the study of molecular structures in plant forage in relation to livestock digestive behavior and nutrient availability. Protein inherent structure, among other factors such as protein matrix, affects nutritive quality, fermentation and degradation behavior in both humans and animals. The relative percentage of protein secondary structure influences protein value. A high percentage of e-sheets usually reduce the access of gastrointestinal digestive enzymes to the protein. Reduced accessibility results in poor digestibility and as a result, low protein value. The objective of this study was to use SRFTIRM to compare protein molecular structure of alfalfa plant tissues transformed with the maize Lc regulatory gene with non-transgenic alfalfa protein within cellular and subcellular dimensions and to quantify protein inherent structure profiles using Gaussian and Lorentzian methods of multi-component peak modeling. Protein molecular structure revealed by this method included a-helices, e-sheets and other structures such as e-turns and random coils. Hierarchical cluster analysis and principal component analysis of the synchrotron data, as well as accurate spectral analysis based on curve fitting, showed that transgenic alfalfa contained a relatively lower (P 0.05) in the ratio of a-helices to e-sheets (average: 1.4) and higher (P 0.05) in the vibrational intensity of protein amide I (average of 24) and amide II areas (average of 10) and their ratio (average of 2.4) compared with non-transgenic alfalfa. Cluster analysis and principal component analysis showed no significant differences between the two genotypes in the broad molecular fingerprint region, amides I and II regions, and the carbohydrate molecular region, indicating they are highly related to each other. The results suggest that transgenic Lc-alfalfa leaves contain similar

  4. FT-IR, NMR spectroscopic and quantum mechanical investigations of two ferrocene derivatives

    Directory of Open Access Journals (Sweden)

    Ö. Alver

    2017-07-01

    Full Text Available New ferrocene derivatives as N-(3-piperidin-1-ylpropylferrocenamide (Fc-3ppa and N-(pyridine-3-ylmethylferrocenamide (Fc-3pica and structural investigations were carried out with 1H, 13C, DEPT 45 or 135, HETCOR, COSY NMR and FT-IR spectroscopic techniques. Characterization of Fc-3ppa (FeC19H26N2O and Fc-3pica (FeC17H16N2O was also supported by density functional theory (DFT used by B3LYP functional and 6-31G(d or 6-311++G(d,p basis sets. From the combination of all the results, it can be clearly seen that syntheses of Fc-3ppa and Fc-3pica have been successfully achieved. Theoretical values are successfully compared against experimental data and B3LYP method is able to provide satisfactory results for predicting NMR properties and vibrational frequencies of the synthesized ferrocene based systems.

  5. A theoretical approach to the relationship between wettability and surface microstructures of epidermal cells and structured cuticles of flower petals.

    Science.gov (United States)

    Taneda, Haruhiko; Watanabe-Taneda, Ayako; Chhetry, Rita; Ikeda, Hiroshi

    2015-05-01

    The epidermal surface of a flower petal is composed of convex cells covered with a structured cuticle, and the roughness of the surface is related to the wettability of the petal. If the surface remains wet for an excessive amount of time the attractiveness of the petal to floral visitors may be impaired, and adhesion of pathogens may be promoted. However, it remains unclear how the epidermal cells and structured cuticle contribute to surface wettability of a petal. By considering the additive effects of the epidermal cells and structured cuticle on petal wettability, a thermodynamic model was developed to predict the wetting mode and contact angle of a water droplet at a minimum free energy. Quantitative relationships between petal wettability and the geometries of the epidermal cells and the structured cuticle were then estimated. Measurements of contact angles and anatomical traits of petals were made on seven herbaceous species commonly found in alpine habitats in eastern Nepal, and the measured wettability values were compared with those predicted by the model using the measured geometries of the epidermal cells and structured cuticles. The model indicated that surface wettability depends on the height and interval between cuticular steps, and on a height-to-width ratio for epidermal cells if a thick hydrophobic cuticle layer covers the surface. For a petal epidermis consisting of lenticular cells, a repellent surface results when the cuticular step height is greater than 0·85 µm and the height-to-width ratio of the epidermal cells is greater than 0·3. For an epidermis consisting of papillate cells, a height-to-width ratio of greater than 1·1 produces a repellent surface. In contrast, if the surface is covered with a thin cuticle layer, the petal is highly wettable (hydrophilic) irrespective of the roughness of the surface. These predictions were supported by the measurements of petal wettability made on flowers of alpine species. The results indicate

  6. The use of UV, FT-IR and Raman spectra for the identification of the newest penem analogs: solutions based on mathematic procedure and the density functional theory.

    Science.gov (United States)

    Cielecka-Piontek, J; Lewandowska, K; Barszcz, B; Paczkowska, M

    2013-02-15

    The application of ultraviolet, FT-IR and Raman spectra was proposed for identification studies of the newest penem analogs (doripenem, biapenem and faropenem). An identification of the newest penem analogs based on their separation from related substances was achieved after the application of first derivative of direct spectra in ultraviolet which permitted elimination of overlapping effects. A combination of experimental and theoretical studies was performed for analyzing the structure and vibrational spectra (FT-IR and Raman spectra) of doripenem, biapenem and faropenem. The calculations were conducted using the density functional theory with the B3LYP hybrid functional and 6-31G(d,p) basis set. The confirmation of the applicability of the DFT methodology for interpretation of vibrational IR and Raman spectra of the newest penem analogs contributed to determination of changes of vibrations in the area of the most labile bonds. By employing the theoretical approach it was possible to eliminate necessity of using reference standards which - considering the instability of penem analogs - require that correction coefficients are factored in. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Role of aromatic structure in pathways of hydrogen transfer and bond cleavage in coal liquefaction: Theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Franz, J.A.; Autrey, T.; Camaioni, D.M. [Pacific Northwest Lab., Richland, WA (United States); Watts, J.D.; Bartlett, R.J. [Univ. of Florida, Gainesville, FL (United States). Quantum Theory Project

    1995-09-01

    The mechanisms by which strong carbon-carbon bonds between aromatic rings and side chains are cleaved under hydropyrolysis conditions remain a subject of wide interest to fuel science. Recently, the authors have studied in detail an alternate pathway for hydrogen atom transfer to {pi}-systems, radical hydrogen transfer (RHT). RHT is the direct, bimolecular transfer of hydrogen from the {beta}-position of an organic radical to the target {pi}-system. In the initial theoretical study, they examined the reaction ethyl radical + ethylene = ethylene + ethyl at the spin-projected UMP2/6-31G** level of theory. Recently, they have used a calibrated ROHF-MNDO-PM3 method to predict thermoneutral RHT barriers for hydrogen transfer between hydroaryl radicals and the corresponding arene. Because of the inherent limitations of semiempirical methods such as ROHF-MNDO-PM3, they have extended the initial work with the ethyl + ethylene study to examine this reaction at the ROHF-MBPT[2]-6-31G** and ROHF-CCSD[T]-6-31G** levels of ab initio theory. The primary objective was to determine how intrinsic RHT barriers change with conjugative stabilization of the radicals. The spin-restricted ROHF approach has been applied to study several RHT reactions, and they present completed ROHF results for the ethyl + ethylene system and preliminary results for the methallyl + butadiene system. The methallyl + butadiene system serves as a model for highly stabilized hydroaryl radicals: the methallyl radical exhibits a C-H bond strength of 46.5 kcal/mol compared to 9-hydroanthracenyl, 43.1 kcal/mol.

  8. Theoretical study of the electronic structure of KLi molecule: Adiabatic and diabatic potential energy curves and dipole moments

    International Nuclear Information System (INIS)

    Dardouri, Riadh; Habli, Héla; Oujia, Brahim; Gadéa, Florent Xavier

    2012-01-01

    Graphical abstract: We present the resulting 12 1 Σ + diabatic potential energy curves where they are labeled D 1 for the ionic Li − K + and D 2 to D 12 for other. Highlights: ► Our ab initio study has been conducted for 48 electronic states of LiK molecule. ► We use pseudo-potential for the core and large basis sets for the Rydberg states. ► The calculations rely on ab initio pseudo-potential and full valence CI approaches. ► Diabatic potentials are analyzed, revealing the strong imprint of the ionic 1 Σ + state. - Abstract: For all states dissociating below the ionic limit Li − K + , we perform an adiabatic and diabatic study for 1 Σ + electronic states dissociating into K (4s, 4p, 4d, 5s, 5p, 5d, 6s) + Li (2s, 2p, 3s). Furthermore, we present the adiabatic results for the 1–11 3 Σ, 1–8 1,3 Π and 1–4 1,3 Δ states. The present calculations on the KLi molecule are complementary to previous theoretical work on this system, including recently observed electronic states that had not been calculated previously. The calculations rely on an ab initio pseudo-potential, Core Polarization Potential operators for the core–valence correlation and full valence CI approaches, combined to an efficient diabatization procedure. For the low-lying states, our spectroscopic constants and vibrational level spacing are in good agreement with the available experimental data. Diabatic potentials and permanent dipole moments are analyzed, revealing the strong imprint of the ionic state in the 1 Σ + adiabatic states.

  9. Theoretical study of the electronic structure of KLi molecule: Adiabatic and diabatic potential energy curves and dipole moments

    Energy Technology Data Exchange (ETDEWEB)

    Dardouri, Riadh, E-mail: dardouririad@yahoo.fr [Laboratoire de Physique Quantique, Faculte des Sciences de Monastir, Avenue de l' Environnement, 5019 Monastir (Tunisia); Habli, Hela [Laboratoire de Physique Quantique, Faculte des Sciences de Monastir, Avenue de l' Environnement, 5019 Monastir (Tunisia); Oujia, Brahim; Gadea, Florent Xavier [Laboratoire de Chimie et Physique Quantique, UMR 5626 du CNRS, Universite de Toulouse, UPS, 118 route de Narbonne, 31062 Toulouse Cedex 4 (France)

    2012-05-03

    Graphical abstract: We present the resulting 12 {sup 1}{Sigma}{sup +} diabatic potential energy curves where they are labeled D{sub 1} for the ionic Li{sup -}K{sup +} and D{sub 2} to D{sub 12} for other. Highlights: Black-Right-Pointing-Pointer Our ab initio study has been conducted for 48 electronic states of LiK molecule. Black-Right-Pointing-Pointer We use pseudo-potential for the core and large basis sets for the Rydberg states. Black-Right-Pointing-Pointer The calculations rely on ab initio pseudo-potential and full valence CI approaches. Black-Right-Pointing-Pointer Diabatic potentials are analyzed, revealing the strong imprint of the ionic {sup 1}{Sigma}{sup +} state. - Abstract: For all states dissociating below the ionic limit Li{sup -}K{sup +}, we perform an adiabatic and diabatic study for {sup 1}{Sigma}{sup +} electronic states dissociating into K (4s, 4p, 4d, 5s, 5p, 5d, 6s) + Li (2s, 2p, 3s). Furthermore, we present the adiabatic results for the 1-11 {sup 3}{Sigma}, 1-8 {sup 1,3}{Pi} and 1-4 {sup 1,3}{Delta} states. The present calculations on the KLi molecule are complementary to previous theoretical work on this system, including recently observed electronic states that had not been calculated previously. The calculations rely on an ab initio pseudo-potential, Core Polarization Potential operators for the core-valence correlation and full valence CI approaches, combined to an efficient diabatization procedure. For the low-lying states, our spectroscopic constants and vibrational level spacing are in good agreement with the available experimental data. Diabatic potentials and permanent dipole moments are analyzed, revealing the strong imprint of the ionic state in the {sup 1}{Sigma}{sup +} adiabatic states.

  10. The spectroscopic (FT-IR, FT-Raman, (l3)C, (1)H NMR and UV) and NBO analyses of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid.

    Science.gov (United States)

    Vitnik, Vesna D; Vitnik, Željko J

    2015-03-05

    In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid (BEPA). BEPA has been characterized by FT-IR, FT-Raman, (1)H NMR, (13)C NMR and UV spectroscopy. The FT-IR and FT-Raman spectra of BEPA were recorded in the solid phase. The optimized geometry was calculated by B3LYP and M06-2X methods using 6-311G(d,p) basis set. The FT-IR and FT-Raman spectra of BEPA were calculated at the same level and were interpreted in terms of Potential Energy Distribution (PED) analysis. The scaled theoretical wavenumber showed very good agreement with the experimental values. The (1)H and (l3)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Independent Atomic Orbital (GIAO) method. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Density plots over the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) energy surface directly identifies the donor and acceptor atoms in the molecule. It also provides information about the charge transfer within the molecule. To obtain chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is plotted over the optimized geometry of the molecule. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Theoretical and experimental study of a modular accelerating structure of travelling waves sections for high gradient tests (MECCANO); Etude theorique et experimentale d`une structure acceleratrice a ondes progressives demontable pour des tests fort gradient (Structure dite ``MECCANO``)

    Energy Technology Data Exchange (ETDEWEB)

    Chanudet, M

    1996-06-04

    A modular system, MECCANO, has been developed at the Laboratoire de l`Accelerateur Lineaire d`Orsay to study the physical and technical phenomena of high electric fields in travelling waves structures in the context of future linear colliders which can reach TeV energies. The behaviour of the electric field inside the section MECCANO is considered from the theoretical point of view with numerical simulations and analytical representations and from the experimental side with low and high power measurements. An infinite and uniform structure is classically described by series of RLC resonant circuits. The basic RF properties of the fundamental mode are given. For a finite section, the matching of a forward or backward travelling wave of any phase advance per cell is also represented by means of RLC circuits. The variations of the reflection and transmission properties of the structure with frequency and a new procedure to match couplers have been modelled and experimentally verified. The electromagnetic behaviour of each cavity and of the whole structure have been studied, the fundamental and first high order modes have been simulated by 2D or 3D codes and measured at low power. The matching of the phase, the amplitude and the reflection level of the accelerator is described. This procedure is found to be extremely delicate due to the abrupt changes in the geometry of the cavities. The structure has been tested at fields superior to 150 MV/m. The behaviour of some materials and surface layers subject to high gradients are presented. (author) 46 refs.

  12. Structural conditions that leads to photoluminescence emission in SrTiO3: An experimental and theoretical approach

    Science.gov (United States)

    Longo, V. M.; de Figueiredo, A. T.; de Lázaro, S.; Gurgel, M. F.; Costa, M. G. S.; Paiva-Santos, C. O.; Varela, J. A.; Longo, E.; Mastelaro, V. R.; DE Vicente, F. S.; Hernandes, A. C.; Franco, R. W. A.

    2008-07-01

    Complex cluster [TiO5ṡVOz] and [SrO11ṡVOz] (where VOz=VOX, VO•, VO••) vacancies were identified in disordered SrTiO3 powders prepared by the polymeric precursor method, based on experimental measurements by x-ray absorption near edge structure spectroscopy. The paramagnetic complex states of [TiO5ṡVO•] and [SrO11ṡVO•] with unpaired electrons were confirmed by electron paramagnetic resonance spectroscopy. The disordered powders showed strong photoluminescence at room temperature. Structural defects of disordered powders, in terms of band diagram, density of states, and electronic charges, were interpreted using high-level quantum mechanical calculations in the density functional framework. The four periodic models used here were consistent with the experimental data and explained the presence of photoluminescence.

  13. Stereoselective green synthesis and molecular structures of highly functionalized spirooxindole-pyrrolidine hybrids - A combined experimental and theoretical investigation

    Science.gov (United States)

    Kumar, Raju Suresh; Almansour, Abdulrahman I.; Arumugam, Natarajan; Soliman, Saied M.; Kumar, Raju Ranjith; Altaf, Mohammad; Ghabbour, Hazem A.; Krishnamoorthy, Bellie Sundaram

    2018-01-01

    Highly functionalized spirooxindole-pyrrolidine hybrids have been synthesized stereoselectively through a [3 + 2] cycloaddition strategy in an ionic liquid, 1-butyl-3-methylimidazolium bromide ([bmim]Br). The structure of these spiro heterocyclic hybrids was elucidated using one and two dimensional NMR spectroscopy, single crystal X-ray crystallographic studies and Density Functional Theory (DFT) calculations. The calculated geometric parameters are in good agreement with the experimental data obtained from the X-ray structures. The Natural Bond Orbital (NBO) calculations on these molecules confirm the electron rich carbonyl oxygen and electron deficient NH groups. The 1H and 13C NMR chemical shifts calculated using GIAO method are in good agreement with the experimental data. The DFT computed polarizability values also suggest the possible NLO activity of these molecules.

  14. Theoretical investigation of pressure-induced structural transitions in americium using GGA+U and hybrid density functional theory methods

    DEFF Research Database (Denmark)

    Verma, Ashok K.; Modak, P.; Sharma, Surinder M.

    2013-01-01

    and pressure-induced structural transitions. Both methods yield equilibrium volume and bulk modulus in good agreement with the experimental results. The GGA+spin orbit coupling+U method reproduced all structural transitions under pressure correctly, but the HYB-DFT method failed to reproduce the observed Am......-I to Am-II transition. Good agreement was found between calculated and experimental equations of states for all phases, but the first three phases need larger U (α) parameters (where α represents the fraction of Hartree-Fock exchange energy replacing the DFT exchange energy) than the fourth phase in order...... to match the experimental data. Thus, neither the GGA+U nor the HYB-DFT methods are able to describe the energetics of Am metal properly in the entire pressure range from 0 GPa to 50 GPa with a single choice of their respectiveU and α parameters. Low binding-energy peaks in the experimental photoemission...

  15. A theoretical and experimental study on manipulating the structure and properties of carbon nanotubes using substitutional dopants

    Science.gov (United States)

    Sumpter, Bobby G.; Huang, Jingsong; Meunier, Vincent; Romo-Herrera, Jose M.; Cruz-Silva, Eduardo; Terrones, Humberto; Terrones, Mauricio

    We examine the possibility of controlling nanotube growth and simultaneously manipulating the nanotube properties by adding elements in minute amounts (such as nitrogen, phosphorous, and sulfur) that are different from carbon and the metal catalyst during the growth process. This procedure is shown to be capable of producing bamboo-type morphologies, heterodoped carbon nanotubes, and Y-junctions. This also represents a critical step toward tailoring properties and controlling nanotube architectures, thus promoting the development of novel materials with unusual electronic applications. The underlying formation mechanisms that lead to the observed structures and morphologies are elucidated using wide-ranging electronic structure calculations that reveal the fundamentally different nature of nitrogen, phosphorous, and sulfur during carbon nanotube growth.

  16. Azo dicarboxylates are not conjugated: X-ray crystal structure and theoretical calculations on di-t-butylazodicarboxylate

    Science.gov (United States)

    Goh, Mean See; Rintoul, Llew; Pfrunder, Michael C.; McMurtrie, John C.; Arnold, Dennis P.

    2015-10-01

    The X-ray crystal structure of trans-di-t-butyl azodicarboxylate (DTBAD, 2) was determined and this revealed that the torsion angle between the Ndbnd N and Cdbnd O double bonds is 84.0(2)°, and that between the anti-disposed Cdbnd O vectors is 180°. This is the first report of the solid state structure of an azodicarboxylate ester. The molecule was subjected to Density Functional Theory geometry optimization at the B3LYP/6-31G(d) level in cyclohexane medium, and the global minimum structure agreed in principle with that determined in the solid state by crystallography. The N-C(O) torsion angle in the optimized structure is 107.7°, and the Cdbnd O vectors lie in an anti relationship. Similar calculations on the unknown cis-Ndbnd N isomer revealed an optimum geometry whose energy is predicted to lie only 11.9 kJ/mol higher than that of the trans isomer. M062X/6-311+G(d) model chemistry was used to determine relative electronic energies and to conduct Natural Bond Orbital (NBO) calculations. Exploration of the energetics of rotations about the N-C(O) bonds revealed a clear preference for near-orthogonality in azodicarboxylates, and suggests almost complete absence of classical conjugation between the neighbouring π bonds. Electronic transitions were simulated using the time-dependent DFT (TD-DFT) approach at the B3LYP/6-311+G(d) level, and the weak band in the near-UV for 2 in cyclohexane was reproduced in the calculations. The electronic isolation of the Ndbnd N bond may be important in the numerous applications of azodicarboxylates in organic synthesis, and the small energy difference between the trans and cis isomers implies the likely involvement of the latter in the successful photochemical diaza-Diels-Alder reaction of diethyl azodicarboxylate with 1,3-cyclohexadiene.

  17. The impact of power market structure on CO2 cost pass-through to electricity prices under quantity competition. A theoretical approach

    International Nuclear Information System (INIS)

    Sijm, J.; Chen, Y.; Hobbs, B.F.

    2012-01-01

    We present a theoretical analysis of the impact of power market structure on the pass-through rate (PTR) of CO2 emissions trading (ET) costs on electricity prices. Market structure refers in particular to the number of firms active in the market and the intensity of oligopolistic competition as measured by the conjectural variation, as well as to the functional form of the power demand and supply curves. In addition, we analyse briefly the impact of other power market-related factors on the PTR of carbon costs to electricity prices. These include in particular the impact of ET-induced changes in the merit order of power generation technologies and the impact of pursuing other market strategies besides maximising generator profit, such as maximising market shares or sales revenues of power companies. Each of these factors can have a significant impact on the rate of passing-through carbon costs to electricity prices.

  18. The impact of power market structure on the pass-through of CO2 emissions trading costs to electricity prices. A theoretical approach

    International Nuclear Information System (INIS)

    Sijm, J.; Chen, Yihsu; Hobbs, B.F.

    2009-06-01

    This paper analyses the impact of power market structure on the pass-through rate (PTR) of CO2 emissions trading costs on electricity prices from a theoretical point of view, including graphical illustrations and mathematical proofs. Market structure refers in particular to the number of firms active in the market as well as to the shape of the power demand and supply curves. In addition, it analyses the impact of other power market related factors on the PTR of carbon costs to electricity prices, notably the impact of ET-induced changes in the merit order of power generation technologies or the impact of pursuing other market strategies besides maximising generators' profits, such as maximising market shares or sales revenues of power companies. It shows that each of these factors can have a significant impact on the rate of passing-through carbon costs to electricity prices

  19. Molecular Basis of Protein Structure in Proanthocyanidin and Anthocyanin-Enhanced Lc-transgenic Alfalfa in Relation to Nutritive Value Using Synchrotron-Radiation FTIR Microspectroscopy: A Novel Approach

    Energy Technology Data Exchange (ETDEWEB)

    Yu, P.; Jonker, A; Gruber, M

    2009-01-01

    To date there has been very little application of synchrotron radiation-based Fourier transform infrared microspectroscopy (SRFTIRM) to the study of molecular structures in plant forage in relation to livestock digestive behavior and nutrient availability. Protein inherent structure, among other factors such as protein matrix, affects nutritive quality, fermentation and degradation behavior in both humans and animals. The relative percentage of protein secondary structure influences protein value. A high percentage of e-sheets usually reduce the access of gastrointestinal digestive enzymes to the protein. Reduced accessibility results in poor digestibility and as a result, low protein value. The objective of this study was to use SRFTIRM to compare protein molecular structure of alfalfa plant tissues transformed with the maize Lc regulatory gene with non-transgenic alfalfa protein within cellular and subcellular dimensions and to quantify protein inherent structure profiles using Gaussian and Lorentzian methods of multi-component peak modeling. Protein molecular structure revealed by this method included a-helices, e-sheets and other structures such as e-turns and random coils. Hierarchical cluster analysis and principal component analysis of the synchrotron data, as well as accurate spectral analysis based on curve fitting, showed that transgenic alfalfa contained a relatively lower (P < 0.05) percentage of the model-fitted a-helices (29 vs. 34) and model-fitted e-sheets (22 vs. 27) and a higher (P < 0.05) percentage of other model-fitted structures (49 vs. 39). Transgenic alfalfa protein displayed no difference (P > 0.05) in the ratio of a-helices to e-sheets (average: 1.4) and higher (P < 0.05) ratios of a-helices to others (0.7 vs. 0.9) and e-sheets to others (0.5 vs. 0.8) than the non-transgenic alfalfa protein. The transgenic protein structures also exhibited no difference (P > 0.05) in the vibrational intensity of protein amide I (average of 24) and amide II

  20. Theoretical Research on Ellipsoidal Structure Methane Gas Detection Based on Near Infrared Light Sources of PbSe Quantum Dots

    Directory of Open Access Journals (Sweden)

    Xiaoxue Xing

    2017-01-01

    Full Text Available To improve the precision and sensitivity of the detection in near infrared gas detection system, the selection of light source and design of gas chamber structure are two key links. In this paper, the near infrared (NIR light sources fabricated with PbSe quantum dots (QDs and a new gas cell structure using an ellipsoid reflector were designed to test the concentration of methane (CH4. The double wavelengths differential detection method was used in the paper. The signal wavelength is 1.665 μm from the NIR QD-based light source with 5.1 nm PbSe QDs. The reference wavelength is 1.943 μm from the NIR QD-based light source with 6.1 nm PbSe QDs. The experimental results show that the differential gain signal could be enhanced 80 times when the major axis, the focus, and the open length of the ellipsoid reflector are 4.18 cm, 3.98 cm, and 0.36 cm, respectively. The structure will be convenient for the signal amplifying, AD converting, and other process in the latter circuits, and therefore both the detection sensitivity and precision can be improved.

  1. Effects of Pt and ionomer ratios on the structure of catalyst layer: A theoretical model for polymer electrolyte fuel cells

    Science.gov (United States)

    Ishikawa, H.; Sugawara, Y.; Inoue, G.; Kawase, M.

    2018-01-01

    The 3D structure of the catalyst layer (CL) in the polymer electrolyte fuel cell (PEFC) is modeled with a Pt/carbon (Pt/C) ratio of 0.4-2.3 and ionomer/carbon (i/C) ratio of 0.5-1.5, and the structural properties are evaluated by numerical simulation. The models are constructed by mimicking the actual shapes of Pt particles and carbon aggregates, as well as the ionomer adhesion in real CLs. CLs with different compositions are characterized by structural properties such as Pt inter-particle distance, ionomer coating thickness, pore size distribution, tortuosity, and ionomer coverage on Pt. The results for Pt/C = 1.0, i/C = 1.0 with Pt loading of 0.3 mg cm-2 and 50% porosity are validated against measured data for CLs with the same composition. With increasing i/C ratio, the smaller pores disappear and the number of isolated pores increases; while the ionomer connection and its coverage on Pt are significantly enhanced at i/C ∼1.0. With increasing Pt/C ratio, the Pt inter-particle distance decreases as the particles connect with each other. The tortuosity of the pores and the ionomer exhibits a trade-off relation depending on the ionomer volume. Further CL design concepts to optimize both O2 diffusion and H+ conduction are discussed.

  2. A Theoretical Study of Love Wave Sensors Based on ZnO–Glass Layered Structures for Application to Liquid Environments

    Science.gov (United States)

    Caliendo, Cinzia; Hamidullah, Muhammad

    2016-01-01

    The propagation of surface acoustic Love modes along ZnO/glass-based structures was modeled and analysed with the goal of designing a sensor able to detect changes in the environmental parameters, such as liquid viscosity changes and minute amounts of mass supported in the viscous liquid medium. Love mode propagation was modeled by numerically solving the system of coupled electro-mechanical field equations and Navier–Stokes equations. The phase and group velocities and the attenuation of the acoustic wave propagating along the 30° tilted c-axis ZnO/glass structure contacting a viscous non-conductive liquid were calculated for different ZnO guiding layer thicknesses, added mass thicknesses, and liquid viscosity and density. The three sensor responses, i.e., the wave phase and group velocity, and attenuation changes are calculated for different environmental parameters and related to the sensor velocity and attenuation sensitivities. The resulted sensitivities to liquid viscosity and added mass were optimized by adjusting the ZnO guiding layer thickness corresponding to a sensitivity peak. The present analysis is valuable for the manufacture and application of the ZnO-glass structure Love wave sensors for the detection of liquid properties, such as viscosity, density and mass anchored to the sensor surface. PMID:27918419

  3. A Theoretical Study of Love Wave Sensors Based on ZnO-Glass Layered Structures for Application to Liquid Environments.

    Science.gov (United States)

    Caliendo, Cinzia; Hamidullah, Muhammad

    2016-12-02

    The propagation of surface acoustic Love modes along ZnO/glass-based structures was modeled and analysed with the goal of designing a sensor able to detect changes in the environmental parameters, such as liquid viscosity changes and minute amounts of mass supported in the viscous liquid medium. Love mode propagation was modeled by numerically solving the system of coupled electro-mechanical field equations and Navier-Stokes equations. The phase and group velocities and the attenuation of the acoustic wave propagating along the 30° tilted c-axis ZnO/glass structure contacting a viscous non-conductive liquid were calculated for different ZnO guiding layer thicknesses, added mass thicknesses, and liquid viscosity and density. The three sensor responses, i.e., the wave phase and group velocity, and attenuation changes are calculated for different environmental parameters and related to the sensor velocity and attenuation sensitivities. The resulted sensitivities to liquid viscosity and added mass were optimized by adjusting the ZnO guiding layer thickness corresponding to a sensitivity peak. The present analysis is valuable for the manufacture and application of the ZnO-glass structure Love wave sensors for the detection of liquid properties, such as viscosity, density and mass anchored to the sensor surface.

  4. A Theoretical Study of Love Wave Sensors Based on ZnO–Glass Layered Structures for Application to Liquid Environments

    Directory of Open Access Journals (Sweden)

    Cinzia Caliendo

    2016-12-01

    Full Text Available The propagation of surface acoustic Love modes along ZnO/glass-based structures was modeled and analysed with the goal of designing a sensor able to detect changes in the environmental parameters, such as liquid viscosity changes and minute amounts of mass supported in the viscous liquid medium. Love mode propagation was modeled by numerically solving the system of coupled electro-mechanical field equations and Navier–Stokes equations. The phase and group velocities and the attenuation of the acoustic wave propagating along the 30° tilted c-axis ZnO/glass structure contacting a viscous non-conductive liquid were calculated for different ZnO guiding layer thicknesses, added mass thicknesses, and liquid viscosity and density. The three sensor responses, i.e., the wave phase and group velocity, and attenuation changes are calculated for different environmental parameters and related to the sensor velocity and attenuation sensitivities. The resulted sensitivities to liquid viscosity and added mass were optimized by adjusting the ZnO guiding layer thickness corresponding to a sensitivity peak. The present analysis is valuable for the manufacture and application of the ZnO-glass structure Love wave sensors for the detection of liquid properties, such as viscosity, density and mass anchored to the sensor surface.

  5. Information Theoretic Subspace Clustering.

    Science.gov (United States)

    He, Ran; Wang, Liang; Sun, Zhenan; Zhang, Yingya; Li, Bo

    2016-12-01

    This paper addresses the problem of grouping the data points sampled from a union of multiple subspaces in the presence of outliers. Information theoretic objective functions are proposed to combine structured low-rank representations (LRRs) to capture the global structure of data and information theoretic measures to handle outliers. In theoretical part, we point out that group sparsity-induced measures ( l 2,1 -norm, l α -norm, and correntropy) can be justified from the viewpoint of half-quadratic (HQ) optimization, which facilitates both convergence study and algorithmic development. In particular, a general formulation is accordingly proposed to unify HQ-based group sparsity methods into a common framework. In algorithmic part, we develop information theoretic subspace clustering methods via correntropy. With the help of Parzen window estimation, correntropy is used to handle either outliers under any distributions or sample-specific errors in data. Pairwise link constraints are further treated as a prior structure of LRRs. Based on the HQ framework, iterative algorithms are developed to solve the nonconvex information theoretic loss functions. Experimental results on three benchmark databases show that our methods can further improve the robustness of LRR subspace clustering and outperform other state-of-the-art subspace clustering methods.

  6. The Theoretical Study of the Beams Supported on a Straining Environment as an Interaction Problem Soil - Structure - Infrastructure Interaction

    Directory of Open Access Journals (Sweden)

    Ana-Raluca Chiriac

    2006-01-01

    Full Text Available Between structure, infrastructure (foundation and soil there is an effective interaction, which has to be taken into account as correctly as possible every time we do the calculation. This effective interaction can be analysed in a global form, considering on one hand the entire building, and on the other hand the soil -- establishment surface, or in an analytical form: we consider first the soil -- infrastructure (foundation interaction and then the structure -- infrastructure one. Without considering the interaction, we cannot make neither the calculation (for the soil according to the limiting deformation state which has to be compatible with the structure’s resistance system, nor calculation for the limiting resistance state, because the correct distribution of efforts along the contact surface between the soil and the structure is unknown, so we cannot determine the zones of plastical equilibrium in the soil massive and the conditions of limited equilibrium. Also, without considering the infrastructure, we cannot correctly calculate the efforts and the deformations which may occur in all resistance elements of the building. Therefore, we cannot talk about limiting state calculation without considering the interaction between the soil and the structure itself. The problem of interaction between building, on one hand and soil foundation, on the other hand, is not approached very much in the specialized literature, because of the big difficulties raised by summarizing all the factors that describe the structure and the environment, which would be more accessible to a practical calculation. A lot of buildings or elements of buildings standing on the soil or on another environment with finite rigidity can be taken into account as beams supported on a straining environment, (continuous foundations, resistance walls, longitudinal and transversal membranes of civil and industrial buildings, hydrotechnic works. Therefore, in the present paper we

  7. Theoretical Investigation of the Structural Stabilities of Ceria Surfaces and Supported Metal Nanocluster in Vapor and Aqueous Phases

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhibo [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Liu, Ning [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Chen, Biaohua [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Li, Jianwei [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Mei, Donghai [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States

    2018-01-25

    Understanding the structural stability and dynamics at the interface between the solid metal oxide and aqueous phase is significant in a variety of industrial applications including heterogeneous catalysis and environmental remediation. In the present work, the stabilities of three low-index ceria (CeO2) surfaces, i.e., (111), (110) and (100) in vapor and aqueous phases were studied using ab initio molecular dynamics simulations and density functional theory (DFT) calculations. Gibbs surface free energies as a function of temperature, water partial pressure, and water coverages were calculated using DFT based atomistic thermodynamic approach. On the basis of surface free energies, the morphology and exposed surface structures of the CeO2 nanoparticle were predicted using Wulff construction principle. It is found that the partially hydroxylated (111) and (100) are two major surface structures of CeO2 nanoparticles in vapor phase at ambient temperature (300 K). As the temperature increases, the fully dehydrated (111) surface gradually becomes the most dominant surface structure. While in aqueous phase, the exposed surface of the CeO2 nanoparticle is dominated by the hydroxylated (110) structure at 393 K. Finally, the morphology and stability of a cuboctahedron Pt13 nanocluster supported on CeO2 surfaces in both gas and aqueous phases were investigated. In gas phase, the supported Pt13 nanocluster has the tendency to wetting the CeO2 surface due to the strong metal-support interaction. The calculated interaction energies suggest the CeO2(110) surface provides the best stability for the Pt13 nanocluster. The CeO2 supported Pt13 nanoclusters are oxidized. Compared to the gas phase, the morphology of the CeO2 supported Pt13 nanocluster is less distorted due to the solvation effect provided by surrounding water molecules in aqueous phase. More electrons are transferred from the Pt13 nanocluster to the CeO2 support, implying the supported Pt13 nanocluster is further

  8. Hydrogenated fullerenes in space: FT-IR spectra analysis

    International Nuclear Information System (INIS)

    El-Barbary, A. A.

    2016-01-01

    Fullerenes and hydrogenated fullerenes are found in circumstellar and interstellar environments. But the determination structures for the detected bands in the interstellar and circumstellar space are not completely understood so far. For that purpose, the aim of this article is to provide all possible infrared spectra for C 20 and C 60 fullerenes and their hydrogenated fullerenes. Density Functional theory (DFT) is applied using B3LYP exchange-functional with basis set 6–31G(d, p). The Fourier transform infrared spectroscopy (FT-IR) is found to be capable of distinguishing between fullerenes, mono hydrogenated fullerenes and fully hydrogenated fullerenes. In addition, deposition of one hydrogen atom outside the fully hydrogenated fullerenes is found to be distinguished by forming H 2 molecule at peak around 4440 cm −1 . However, deposition of one hydrogen atom inside the fully hydrogenated fullerenes cannot be distinguished. The obtained spectral structures are analyzed and are compared with available experimental results.

  9. Ftir study of gamma irradiation LDPE film in air

    International Nuclear Information System (INIS)

    Moura, Esperidiana A.B.; Silva, Andre L.A.; Gouvea, Paulo H.D.; Silva, Leonardo G. Andrade e; Gouvea, Douglas; Castro, Ricardo H.R.; Wiebeck, Helio; Kawano, Yoshio

    2003-01-01

    The use of the ionizing radiation for application in plastic packaging, to improve some of properties and for radiation sterilization, has been gaining popularity in the packaging industry. As a consequence of the irradiation, plastic packaging materials can undergo some chemical and physical alterations in their basic function, mainly concerning the protection characteristics. Since changes in physical properties of irradiated packaging films reflect radiation-induced chemical changes in molecular structure, in this work, an investigation was performed by Ftir analysis of LDPE film before and after radiation. Film samples were irradiated with doses between 0 Gy and 100 kGy, at room temperature and in the presence of air. The results showed alterations in the molecular structure, according to the absorbed radiation dose. (author)

  10. Fluorescence and FTIR Spectra Analysis of Trans-A2B2-Substituted Di- and Tetra-Phenyl Porphyrins

    Directory of Open Access Journals (Sweden)

    Chantal Andraud

    2010-08-01

    Full Text Available A series of asymmetrically substituted free-base di- and tetra-phenylporphyrins and the associated Zn-phenylporphyrins were synthesized and studied by X-ray diffraction, NMR, infrared, electronic absorption spectra, as well as fluorescence emission spectroscopy, along with theoretical simulations of the electronic and vibration structures. The synthesis selectively afforded trans-A2B2 porphyrins, without scrambling observed, where the AA and BB were taken as donor- and acceptor-substituted phenyl groups. The combined results point to similar properties to symmetrically substituted porphyrins reported in the literature. The differences in FTIR and fluorescence were analyzed by means of detailed density functional theory (DFT calculations. The X-ray diffraction analysis for single crystals of zinc-containing porphyrins revealed small deviations from planarity for the porphyrin core in perfect agreement with the DFT optimized structures. All calculated vibrational modes (2162 modes for all six compounds studied were found and fully characterized and assigned to the observed FTIR spectra. The most intense IR bands are discussed in connection with the generic similarity and differences of calculated normal modes. Absorption spectra of all compounds in the UV and visible regions show the typical ethio type feature of meso-tetraarylporphyrins with a very intense Soret band and weak Q bands of decreasing intensity. In diphenyl derivatives, the presence of only two phenyl rings causes a pronounced hypsochromic shift of all bands in the absorption spectra. Time-dependent DFT calculations revealed some peculiarities in the electronic excited states structure and connected them with vibronic bands in the absorption and fluorescence spectra from associated vibrational sublevels.

  11. Comparative theoretical and experimental study on novel tri-quinoline system and its anticancer studies

    Science.gov (United States)

    Gayathri, Kasirajan; Radhika, Ramachandran; Shankar, Ramasamy; Malathi, Mahalingam; Savithiri, Krishnaswamy; Sparkes, Hazel A.; Howard, Judith A. K.; Mohan, Palathurai Subramaniam

    2017-04-01

    A novel compound 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline 3 bearing a tri-quinoline moiety has been synthesized from 2-chloro-3,6-dimethyl quinoline 1 and 8-hydroxy quinoline 2 using dry acetone and K2CO3 as a base. 3 has been characterized by using FT-IR, FT-Raman, UV-Vis, 1H NMR, 13C NMR spectra and single crystal X-ray diffraction methods. We have also made a combined experimental and theoretical study on the molecular structure, vibrational spectra, NMR, FT-IR, FT-Raman and UV-Vis spectra of 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline. The theoretical studies of the title compound have been evaluated by using density functional theory calculations using B3LYP/6-31+G(d,p) and M06-2X/6-31+G(d,p) level of theories. The calculated theoretical values were found to be in good agreement with the experimental findings. The single crystal structure 3 crystallized in the orthorhombic space group Pna21. The compound 3 exhibits higher cytotoxicity in human cervical cancer cell lines (HeLa) than human breast cancer cell lines (MCF7).

  12. Heteroleptic complexes of Zn(II) based on 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide: Synthesis, structural characterization, theoretical studies and antibacterial activity

    Science.gov (United States)

    Azarkish, Mohammad; Akbari, Alireza; Sedaghat, Tahereh; Simpson, Jim

    2017-04-01

    Four new ternary complexes, [ZnL (2,2‧-bipy)] (1), Zn2L2(4,4‧-bipy)] (2), [ZnL(Imd)]·H2O (3) and [ZnL3(MeImd)] (4), have been synthesized from the reaction of Zn(II) acetate with 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide (H2L) in the presence of a heterocyclic base, 2,2‧-bipyridine, 4,4‧-bipyridine, imidazole or 2-methylimidazole, as an auxiliary ligand. The complexes have been investigated by elemental analysis and FT-IR, UV-Vis and 1HNMR spectroscopy. These data show that the thiosemicarbazone acts as a tridentate dianionic ligand and coordinates via the thiol group, imine nitrogen, and phenolic oxygen. The coordination sphere was completed by the nitrogen atom(s) of the secondary ligand. The structure of 1 was also confirmed by X-ray crystallography and shown to be a five coordinate complex with coordination geometry between the square-pyramidal and trigonal-bipyramidal. Density functional theory (DFT) calculations including geometry optimization, vibrational frequencies and electronic absorptions have been performed for 1 with the B3LYP functional at the TZP(6-311G*) basis set using the Gaussian 03 or ADF 2009 packages. The optimization calculation showed that the crystallographically determined geometry parameters can be reproduced with that basis set. Experimental IR frequencies and calculated vibration frequencies also support each other. The in vitro antibacterial activities of the ligand and complexes have been evaluated against Gram-positive (B. subtilis and S. aureus) and Gram-negative (P. aeruginosa) bacteria and compared with the standard antibacterial drugs. The results reveal that all of the complexes show much better activity in comparison to the individual thiosemoicarbazone ligand (H2L), against all bacterial strains used, with complex 3 showing the most promising results.

  13. Theoretical physics

    CERN Document Server

    Joos, Georg

    1986-01-01

    Among the finest, most comprehensive treatments of theoretical physics ever written, this classic volume comprises a superb introduction to the main branches of the discipline and offers solid grounding for further research in a variety of fields. Students will find no better one-volume coverage of so many essential topics; moreover, since its first publication, the book has been substantially revised and updated with additional material on Bessel functions, spherical harmonics, superconductivity, elastomers, and other subjects.The first four chapters review mathematical topics needed by theo

  14. FTIR-Microspectroscopy of Prion-Infected Nervous Tissue

    Energy Technology Data Exchange (ETDEWEB)

    Kretlow,A.; Wang, Q.; Kneipp, J.; Lasch, P.; Beekes, M.; Miller, L.; Naumann, D.

    2006-01-01

    The family of transmissible spongiform encephalopathies (TSE), also termed prion diseases, is a group of fatal, neurodegenerative diseases characterized by the accumulation of a misfolded protein, the disease-associated prion protein PrPSc. This glycoprotein differs in secondary structure from its normal, cellular isoform PrPC, which is physiologically expressed mostly by neurons. Scrapie is a prion disease first described in the 18th century in sheep and goats, and has been established as a model in rodents to study the pathogenesis and pathology of prion diseases. Assuming a multitude of molecular parameters change in the tissue in the course of the disease, FTIR microspectroscopy has been proposed as a valuable new method to study and identify prion-affected tissues due to its ability to detect a variety of changes in molecular structure and composition simultaneously. This paper reviews and discusses results from previous FTIR microspectroscopic studies on nervous tissue of scrapie-infected hamsters in the context of histological and molecular alterations known from conventional pathogenesis studies. In particular, data from studies reporting on disease-specific changes of protein structure characteristics, and also results of a recent study on hamster dorsal root ganglia (DRG) are discussed. These data include an illustration on how the application of a brilliant IR synchrotron light source enables the in situ investigation of localized changes in protein structure and composition in nervous cells or tissue due to PrPSc deposition, and a demonstration on how the IR spectral information can be correlated with results of complementary studies using immunohistochemistry and x-ray fluorescence techniques. Using IR microspectroscopy, some neurons exhibited a high accumulation of disease-associated prion protein evidenced by an increased amount of beta-sheet at narrow regions in or around the infected nervous cells. However, not all neurons from terminally diseased

  15. Theoretical study of the structural and electronic properties of novel stanene-based buckled nanotubes and their adsorption behaviors

    Science.gov (United States)

    Abbasi, Amirali; Sardroodi, Jaber Jahanbin; Ebrahimzadeh, Alireza Rastkar; Yaghoobi, Mina

    2018-03-01

    Density functional theory calculations were performed to investigate the geometrical, electronic and adsorption properties of stanene based nanotubes in order to fully exploit the gas sensing capability of these nanotubes. The strain energy, structural parameters and electronic properties of stanene-based nanotubes with armchair and zigzag chirality with various diameters were examined in detail. The results show that, these nanotubes have a buckled structure, in which the tin atoms were arranged in chair-like honeycomb configuration. Calculated strain energy for considered nanotubes are relatively small compared to some other nanotubes pointed to flexibility of stanene mono layer. It was found that the strain energies for (4, 0), (5, 0) and (6, 0) nanotubes have negative values, indicating their stability with respect to stanene nanosheet. The band structure calculations reveal that the armchair nanotubes are semiconductors with two maximums with nearly same energies in valence band. However, the zigzag ones show both conductor and semiconductor behaviors by direct band gap in ᴦ point. Also the spatial distribution of molecular orbitals in valence band maximums and conduction band minimums were presented and discussed. Moreover, the adsorption behaviors of (6, 6) and (8, 8) nanotubes as chemical O3 detection device were investigated in detail. We found that O3 molecule dissociates into O2 over the considered nanotubes, being an effective strategy to help in the reduction of the concentration of these harmful pollutants in the environment. The results also suggest that O3 dissociation over the (6, 6) nanotube is more favorable in energy than that on the (8, 8) nanotube. The results present a great potential of stanene based nanotube for application as a highly sensitive ozone gas sensor.

  16. XRD and FTIR crystallinity indices in sound human tooth enamel and synthetic hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Gasga, José, E-mail: jreyes@fisica.unam.mx [Instituto de Física, UNAM, Circuito de la Investigación Científica s/n., Cd. Universitaria, Coyoacán 04510, México, D.F. (Mexico); Martínez-Piñeiro, Esmeralda L., E-mail: esmemapi@gmail.com [Instituto de Física, UNAM, Circuito de la Investigación Científica s/n., Cd. Universitaria, Coyoacán 04510, México, D.F. (Mexico); Rodríguez-Álvarez, Galois, E-mail: galoisborre@yahoo.com [Instituto de Física, UNAM, Circuito de la Investigación Científica s/n., Cd. Universitaria, Coyoacán 04510, México, D.F. (Mexico); Tiznado-Orozco, Gaby E., E-mail: gab0409@yahoo.com.mx [Unidad Académica de Odontología, Universidad Autónoma de Nayarit, Edificio E7, Ciudad de la Cultura “Amado Nervo”, C.P. 63190 Tepic, Nayarit (Mexico); García-García, Ramiro, E-mail: ramiro@fisica.unam.mx [Instituto de Física, UNAM, Circuito de la Investigación Científica s/n., Cd. Universitaria, Coyoacán 04510, México, D.F. (Mexico); and others

    2013-12-01

    The crystallinity index (CI) is a measure of the percentage of crystalline material in a given sample and it is also correlated to the degree of order within the crystals. In the literature two ways are reported to measure the CI: X-ray diffraction and infrared spectroscopy. Although the CI determined by these techniques has been adopted in the field of archeology as a structural order measure in the bone with the idea that it can help e.g. in the sequencing of the bones in chronological and/or stratigraphic order, some debate remains about the reliability of the CI values. To investigate similarities and differences between the two techniques, the CI of sound human tooth enamel and synthetic hydroxyapatite (HAP) was measured in this work by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), at room temperature and after heat treatment. Although the (CI){sub XRD} index is related to the crystal structure of the samples and the (CI){sub FTIR} index is related to the vibration modes of the molecular bonds, both indices showed similar qualitative behavior for heat-treated samples. At room temperature, the (CI){sub XRD} value indicated that enamel is more crystalline than synthetic HAP, while (CI){sub FTIR} indicated the opposite. Scanning (SEM) and transmission (TEM) images were also used to corroborate the measured CI values. - Highlights: • XRD and FTIR crystallinity indices for tooth enamel and synthetic HAP were obtained. • SEM and TEM images were more correlated with (CI){sub XRD} than with (CI){sub FTIR}. • Regardless of the temperature, (CI){sub XRD} and (CI){sub FTIR} showed similar behavior. • XRD and FTIR crystallinity indices resulted in a fast and qualitative measurement.

  17. Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Pilar; Largo, Antonio; Vega-Vega, Álvaro; Barrientos, Carmen, E-mail: cbb@qf.uva.es [Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain)

    2015-05-14

    The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader’s quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN ({sup 1}Σ) and hydrideisocyanidezinc HZnNC ({sup 1}Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn]{sup +} composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn{sup +} ({sup 2}Σ) and HCNZn{sup +} ({sup 2}Σ)

  18. Theoretical studies on carbon and silicon clusters: Comparison of the structures and stabilities of neutral and ionic forms

    International Nuclear Information System (INIS)

    Raghavachari, K.

    1989-01-01

    Optimized molecular geometries and electronic structures are determined for neutral, positively charged, and negatively charged carbon and silicon clusters containing up to ten atoms. The effects of polarization functions and electron correlation are included in these calculations. Carbon clusters have linear or monocyclic ground state geometries whereas silicon clusters containing five or more atoms have three-dimensional ground state structures. Neutral C 4 , C 6 and C 8 all have linear and monocyclic isomers of comparable stability whereas the ionic forms appear to be generally more stable as linear geometrical arrangements. In the case of neutral and positively charged carbon clusters, the odd-numbered clusters are significantly more stable than the adjacent even-numbered clusters whereas the opposite order of stability occurs for the negative ions. This is due to the large values of the electron affinities of the linear forms of even-numbered clusters such as C 4 and C 6 . The relative stabilities of silicon clusters do not change with the charge state of the clusters. (orig.)

  19. Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight-binding approaches

    International Nuclear Information System (INIS)

    Xu, Chunhui.

    1991-01-01

    Semiempirical interatomic potentials are developed for silicon and carbon by modeling the total energy of the system using tight-binding approaches. The parameters of the models were obtained by fitting to results from accurate first-principles Local Density Functional calculations. Applications to the computation of phonons as a function of volume for diamond-structured silicon and carbon and the thermal expansions for silicon and diamond yields results which agree well with experiment. The physical origin of the negative thermal expansion observed in silicon is explained. A tight-binding total energy model is generated capable of describing carbon systems with a variety of atomic coordinations and topologies. The model reproduces the total energy versus volume curves of various carbon polytypes as well as phonons and elastic constants of diamond and graphite. The model has also been used in the molecular-dynamics simulation of the properties of carbon clusters. The calculated ground-state geometries of small clusters (C 2 --C 10 ) correlates well with results from accurate quantum chemical calculations, and the structural trend of clusters from C 2 to C 60 are investigated. 67 refs., 19 figs

  20. Electronic structure and STM images simulation of defects on hBN/ black-phosphorene heterostructures: A theoretical study

    Science.gov (United States)

    Ospina, D. A.; Cisternas, E.; Duque, C. A.; Correa, J. D.

    2018-03-01

    By first principles calculations which include van der Waals interactions, we studied the electronic structure of hexagonal boron-nitride/black-phosphorene heterostructures (hBN/BP). In particular the role of several kind of defects on the electronic properties of black-phosphorene monolayer and hBN/BP heterostructure was analyzed. The defects under consideration were single and double vacancies, as well Stone-Wale type defects, all of them present in the phosphorene layer. In this way, we found that the electronic structure of the hBN/BP is modified according the type of defect that is introduced. As a remarkable feature, our results show occupied states at the Fermi Level introduced by a single vacancy in the energy gap of the hBN/BP heterostructure. Additionally, we performed simulations of scanning tunneling microscopy images. These simulations show that is possible to discriminate the kind of defect even when the black-phosphorene monolayer is part of the heterostructure hBN/BP. Our results may help to discriminate among several kind of defects during experimental characterization of these novel materials.

  1. Experimental and theoretical study of dielectrophoretic particle trapping in arrays of insulating structures: Effect of particle size and shape.

    Science.gov (United States)

    Saucedo-Espinosa, Mario A; Lapizco-Encinas, Blanca H

    2015-05-01

    Insulator-based dielectrophoresis (iDEP) employs insulating structures embedded in a microchannel to produce electric field gradients. This contribution presents a detailed analysis of the regions within an iDEP system where particles are likely to be retained due to dielectrophoretic trapping in a microchannel with an array of cylindrical insulating structures. The effects of particle size and shape on dielectrophoretic trapping were analyzed by employing 1 and 2 μm polystyrene particles and Escherichia coli cells. This research aims to study the mechanism behind dielectrophoretic trapping and develop a deeper understanding of iDEP systems. Mathematical modeling with COMSOL Multiphysics was employed to assess electrokinetic and dielectrophoretic particle velocities. Experiments were carried out to determine the location of dielectrophoretic barriers that block particle motion within an iDEP microchannel; this supported the estimation of a correction factor to match experiments and simulations. Particle velocities were predicted with the model, demonstrating how the different forces acting on the particles are in equilibrium when particle trapping occurs. The results showed that particle size and shape have a significant effect on the magnitude, location, and shape of the regions of dielectrophoretic trapping of particles, which are defined by DEP isovelocity lines and EK isovelocity lines. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Synthesis, crystal structure and theoretical analysis of intermolecular interactions in two biologically active derivatives of 1,2,4-triazoles

    Science.gov (United States)

    Shukla, Rahul; Mohan, T. P.; Vishalakshi, B.; Chopra, Deepak

    2017-04-01

    In the present study, we have synthesized and structurally characterized two biologically active derivatives of 1,2,4 triazoles, namely 3-(4-fluoro-3-phenoxyphenyl)-1-(piperidin-1-ylmethyl)-1H-1,2,4-triazole-5(4H)-thione (TR) and 1-((3-(4-fluoro-3-phenoxyphenyl)-5-(methylthio)-1H-1,2,4-triazol-1-yl)methyl)piperidine (TR1) via single crystal X-ray diffraction. Both the structures show the presence of various intermolecular interactions in the crystalline solid such as Csbnd H…F, Csbnd H…S, Csbnd H…N, Csbnd H…O, Csbnd H … π, and π … π intermolecular interactions. The role of these interactions in molecular packing was analyzed, and the nature of these interactions was evaluated through computational procedures using PIXEL. Hirshfeld analysis further reveals that the contribution of H…F interactions was more prominent towards packing as compared to H…N/O intermolecular interactions.

  3. Effect of the van der Waals interaction on the electron energy-loss near edge structure theoretical calculation.

    Science.gov (United States)

    Katsukura, Hirotaka; Miyata, Tomohiro; Tomita, Kota; Mizoguchi, Teruyasu

    2017-07-01

    The effect of the van der Waals (vdW) interaction on the simulation of the electron energy-loss near edge structure (ELNES) by a first-principles band-structure calculation is reported. The effect of the vdW interaction is considered by the Tkatchenko-Scheffler scheme, and the change of the spectrum profile and the energy shift are discussed. We perform calculations on systems in the solid, liquid and gaseous states. The transition energy shifts to lower energy by approximately 0.1eV in the condensed (solid and liquid) systems by introducing the vdW effect into the calculation, whereas the energy shift in the gaseous models is negligible owing to the long intermolecular distance. We reveal that the vdW interaction exhibits a larger effect on the excited state than the ground state owing to the presence of an excited electron in the unoccupied band. Moreover, the vdW effect is found to depend on the local electron density and the molecular coordination. In addition, this study suggests that the detection of the vdW interactions exhibited within materials is possible by a very stable and high resolution observation. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Theoretical investigation of the thermodynamic structures and kinetic water-exchange reactions of aqueous Al(III)-salicylate complexes

    Science.gov (United States)

    Shi, Wenjing; Jin, Xiaoyan; Dong, Shaonan; Bi, Shuping

    2013-11-01

    Density functional theory (DFT) calculations were performed on the structures and water-exchange reactions of aqueous Al(III)-salicylate complexes. Based on the four models (gas phase (GP); polarizable continuum model (PCM), which estimates the bulk solvent effect; supermolecule model (SM), which considers the explicit solvent effect, and supermolecule-polarizable continuum model (SM-PCM), which accounts for both types of solvent effects), we systematically conducted this study by examining three different properties of the complexes. (1) The microscopic properties of the aqueous Al(III)-salicylate complexes were studied by optimizing their various structures (including the possible 1:1 mono- and bidentate complexes, cis and trans isomers of the 1:2 bidentate complexes and 1:3 bidentate complexes) at the B3LYP/6-311+G(d, p) level. (2) The 27Al and 13C NMR chemical shifts were calculated using the GIAO method at the HF/6-311+G(d, p) level. The calculation results show that the values obtained with the SM-PCM models are in good agreement with the experimental data available in the literature, indicating that the models we employed are appropriate for Al(III)-salicylate complexes. (3) The water-exchange reactions of 1:1 mono- and bidentate Al(III)-salicylate complexes were simulated using supermolecule models at the B3LYP/6-311+G(d, p) level. The logarithm of the water-exchange rate constant (log kex) of the 1:1 bidentate complex predicted using the "log kex-dAl-OH2" correlation is 4.0, which is in good agreement with the experimental value of 3.7, whereas the calculated range of log kex of the 1:1 monodentate complexes is 1.3-1.9. By effectively combining the results for the thermodynamic static structures with the simulations of the kinetic water-exchange reactions, this work promotes further understanding of the configurations and formation mechanism of Al(III)-salicylate complexes.

  5. Inhibitory effects of deferasirox on the structure and function of bovine liver catalase: a spectroscopic and theoretical study.

    Science.gov (United States)

    Moradi, M; Divsalar, A; Saboury, A A; Ghalandari, B; Harifi, A R

    2015-01-01

    Deferasirox (DFX), as an oral chelator, is used for treatment of transfusional iron overload. In this study, we have investigated the effects of DFX as an iron chelator, on the function and structure of bovine liver catalase (BLC) by different spectroscopic methods of UV-visible, fluorescence, and circular dichroism (CD) at two temperatures of 25 and 37 °C. In vitro kinetic studies showed that DFX can inhibit the enzymatic activity in a competitive manner. KI value was calculated 39 nM according to the Lineweaver-Burk plot indicating a high rate of inhibition of the enzyme. Intrinsic fluorescence data showed that increasing the drug concentrations leads to a significant decrease in the intrinsic emission of the enzyme indicating a significant change in the three-dimensional environment around the chromophores of the enzyme structure. By analyzing the fluorescence quenching data, it was found that the BLC has two binding sites for DFX and the values of binding constant at 25 and 37 °C were calculated 1.7 × 10(7) and 3 × 10(7) M(-1), respectively. The static type of quenching mechanism is involved in the quenching of intrinsic emission of enzyme. The thermodynamic data suggest that hydrophobic interactions play a major role in the binding reaction. UV-vis spectroscopy results represented the changes in tryptophan (Trp) absorption and Soret band spectra, which indicated changes in Trp and heme group position caused by the drug binding. Also, CD data represented that high concentrations of DFX lead to a significant decreasing in the content of β-sheet and random coil accompanied an increasing in α-helical content of the protein. The molecular docking results indicate that docking may be an appropriate method for prediction and confirmation of experimental results and also useful for determining the binding mechanism of proteins and drugs. According to above results, it can be concluded that the DFX can chelate the Fe(III) on the enzyme active site leading

  6. Symmetry and Structural Properties of Condensed Matter - Proceedings of the 4th International School on Theoretical Physics

    Science.gov (United States)

    Lulek, T.; Florek, W.; Lulek, B.

    1997-07-01

    The Table of Contents for the book is as follows: * Preface * Committees and Sponsors * Eugene Wigner and Translational Symmetries * PART A. GROUP ACTION ON SETS AND HIDDEN SYMMETRIES; BETHE ANSATZ * Physical Implications of Crystal Symmetry and Time Reversal * Bethe's Ansatz and the Marshall Rule * Symmetry Properties of Small Amounts of Matter: Clusters and Surface Reconstructions * Analyticity of Bloch and Wannier Functions -- Properties of Berry Phases * τ-Numeration, τ-Wavelets and Diffraction Formulas for the Fibonacci Chain * Dynamical Symmetry * Lorentz Group in Condensed Matter Physics * Geometric Properties of Potentials of Electric Charges * Quadratic Algebra as Dynamic Symmetry * Energy Eigenstates of High Symmetry Electron Systems by Means of Subspace Density Functionals * Optical Tensors in Spatially Modulated Magnetic Systems * Thermodynamic Properties of Spin Systems by Means of the Method of Hierarchy of Algebras * Isoenergetic Surfaces and the Density of States in Low-Symmetrical Crystals * Critical Comments on the Infinite Volume Limit * Orbit Spaces of Compact Linear Groups * The Orbit Space Approach to the Theory of Phase Transitions: The Non-Coregular Case * PART B. MOLECULAR PHYSICS, SYMMETRIC AND UNITARY GROUPS * Combinatorial Aspects of Representations of the Unitary Group * Plethysm in Physics and Chemistry Applications * Group Theory and the Meaning of Life? * Finite States and the Constructive Theory of Discrete Structures * Affine Kac-Moody Algebras and Their Representations * Quantum Systems with Finite Hilbert Space * Casimir Operators of the Unitary Group and Spectral Density Distribution Moments * Quasi-Exact Solvability of a System of Coupled Equations: The Canonical Form of the Rabi and E ⊗ ɛ Jahn-Teller Hamiltonians * Affine Kac-Moody Algebras and the D-Dimensional Hydrogen Atom * Symmetry Classification of Magnetic Excitations in Thulium Iron Garnet * Spectral Density of a Periodic J-Matrix * PART C. STATISTICS OF PARTICLES

  7. Theoretical simulations of the structural stabilities, elastic, thermodynamic and electronic properties of Pt3Sc and Pt3Y compounds

    Science.gov (United States)

    Boulechfar, R.; Khenioui, Y.; Drablia, S.; Meradji, H.; Abu-Jafar, M.; Omran, S. Bin; Khenata, R.; Ghemid, S.

    2018-05-01

    Ab-initio calculations based on density functional theory have been performed to study the structural, electronic, thermodynamic and mechanical properties of intermetallic compounds Pt3Sc and Pt3Y using the full-potential linearized augmented plane wave(FP-LAPW) method. The total energy calculations performed for L12, D022 and D024 structures confirm the experimental phase stability. Using the generalized gradient approximation (GGA), the values of enthalpies formation are -1.23 eV/atom and -1.18 eV/atom for Pt3Sc and Pt3Y, respectively. The densities of states (DOS) spectra show the existence of a pseudo-gap at the Fermi level for both compounds which indicate the strong spd hybridization and directing covalent bonding. Furthermore, the density of states at the Fermi level N(EF), the electronic specific heat coefficient (γele) and the number of bonding electrons per atom are predicted in addition to the elastic constants (C11, C12 and C44). The shear modulus (GH), Young's modulus (E), Poisson's ratio (ν), anisotropy factor (A), ratio of B/GH and Cauchy pressure (C12-C44) are also estimated. These parameters show that the Pt3Sc and Pt3Y are ductile compounds. The thermodynamic properties were calculated using the quasi-harmonic Debye model to account for their lattice vibrations. In addition, the influence of the temperature and pressure was analyzed on the heat capacities (Cp and Cv), thermal expansion coefficient (α), Debye temperature (θD) and Grüneisen parameter (γ).

  8. Silicene: Recent theoretical advances

    KAUST Repository

    Lew Yan Voon, L. C.

    2016-04-14

    Silicene is a two-dimensional allotrope of silicon with a puckered hexagonal structure closely related to the structure of graphene and that has been predicted to be stable. To date, it has been successfully grown in solution (functionalized) and on substrates. The goal of this review is to provide a summary of recent theoretical advances in the properties of both free-standing silicene as well as in interaction with molecules and substrates, and of proposed device applications.

  9. Coordination of extraframework Li+ cation in the MCM-22 and MCM-36 zeolite: FTIR study of CO adsorbed

    Czech Academy of Sciences Publication Activity Database

    Bulánek, R.; Kolářová, M.; Eliášová, Pavla; Čejka, Jiří

    2013-01-01

    Roč. 19, č. 2 (2013), s. 455-463 ISSN 0929-5607 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : FTIR * CO * adsorption microcalorimetry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.735, year: 2013

  10. Shipp-in-Bottle Synthesis of Pt-Rh Carbonyls in NaX and NaY: FTIR Study

    Czech Academy of Sciences Publication Activity Database

    Brabec, Libor

    2001-01-01

    Roč. 169, 1/2 (2001), s. 127-136 ISSN 1381-1169 R&D Projects: GA AV ČR IAA4040710 Institutional research plan: CEZ:AV0Z4040901 Keywords : Pt-Rh carbonyls * FTIR * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.520, year: 2001

  11. FT-IR and FT-Raman spectra, thermo dynamical behavior, HOMO and LUMO, UV, NLO properties, computed frequency estimation analysis and electronic structure calculations on α-bromotoluene.

    Science.gov (United States)

    Govindarajan, M; Periandy, S; Carthigayen, K

    2012-11-01

    In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4,000 cm(-1) and 50-4,000 cm(-1), respectively, for the title molecules. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartee Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The influences of bromine atom and methyl group on the geometry of benzene and its normal modes of vibrations have also been discussed. The results of the calculations were applied to simulated spectra of the title compounds, which show excellent agreement with observed spectra. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  13. [FTIR study on the finger nail with carcinoma of nasopharynx].

    Science.gov (United States)

    Dong, Qin; Liu, Gang; Liu, Tian-hui

    2004-12-01

    Finger nails from twenty normal people and three with carcinoma of nasopharynx were studied by Fourier Transform Infrared (FTIR) technique. The results showed that there are obvious differences between FTIR spectra of them in spectral parameters such as frequency, intensity and band shape etc. The most striking differences in the spectra were observed in the change of amide II, the disappearance of delta(s) (CH3) peak, and at 874.0 cm(-1) whether appeared an absorption peak. The changes involving the phosphate symmetric stretching nu(s, PO2-) and asynmmetric stretching nu(as, PO2-) modes, the CH3 and CH2 groups stretching (v(s, CH2), nu(as, CH3)) bending (delta (CH3)) modes and the C-O stretching nu (C-O) mode were discussed. In addition, the changes of structure of hydrogen-bonding of nucleic acid and cell proteins and the packing and the conformational structure of the membrane lipids were analysed. The average wave number of band of nu(s) (PO2-) shifted from 1080.0 to 1077.6 cm(-1) and that of nu(as) (PO2-) shifted from 1239.4 to 1238.4 cm(-1), which indicated that the degree of hydrogen-bonding formed by oxygen atom of the phosphodiester groups of nucleic acids was weakened. The average wave number of band of delta (CH2) of membrane lipids shifted from 1453.1 to 1453.7 cm(-1), and its peak intensity was slightly enhanced, which suggested that the conformational structure of the methylene chains of membrane lipids is more disordered than in normal nail.

  14. [FTIR study on the normal and cancerous stomach tissues].

    Science.gov (United States)

    Tong, Y; Lin, Y

    2001-06-01

    Tissues of cancerous and corresponding normal stomach were studied by FTIR technique. The results showed that there are obvious differences between FTIR spectra of them in spectral parameters such as frequency, intensity and band shape etc. The changes involving the phosphate symmetric stretching nu s, PO2- and asymmetric stretching nu as, PO2- modes, the CH3 and CH2 groups stretching (nu s, CH2, nu as, CH3) and bending (delta CH2) modes and the C-O stretching nu C-O mode were discussed. In addition, the changes of structure of hydrogen-bonding of nucleic acid and cell proteins and the packing and the conformational structure of the membrance lipids were analysed further. The average wavenumber of band of nu s, PO2- shifted from 1,080.92 cm-1 to 1,085.93 cm-1 and that of nu as, PO2- shifted from 1,239.64 cm-1 to 1,238.73 cm-1 which indicated that the degree of hydrogen-bonding formed by oxygen atom of the phosphodiester groups of nucleic acids was increased. The average wavenumber of band of delta CH2 of membrance lipids shifted from 1,455.23 cm-1 to 1,457.37 cm-1 that suggested that the conformational structure of the methylene chains of membrance lipids is more disordered than in normal tissues. The shift of band of nu C-O of cell proteins from 1,166.08 cm-1 to 1,166.58 cm-1 indicated that the hydrogen-bond of cell proteins become weaker.

  15. A systematic theoretical study of the electronic structures of porphyrin dimers: DFT and TD-DFT calculations on diporphyrins linked by ethane, ethene, ethyne, imine, and azo bridges.

    Science.gov (United States)

    Rintoul, Llew; Harper, Shannon R; Arnold, Dennis P

    2013-11-21

    Theoretical calculations of the geometries, electronic structures and electronic absorption spectra of a series of covalently-linked porphyrin dimers are reported. The diporphyrins comprise 5,10,15-triphenylporphyrinatozinc(II) (ZnTriPP) units linked through the meso carbons by two-atom bridges, namely 1,2-ethanediyl (1), trans-1,2-ethenediyl (2), ethynediyl (3), 1,2-iminomethenediyl (4), and transdiazenediyl (5). The structures were optimised in toluene solvent by Density Functional Theory (DFT), using the integral equation formalism variant of the polarizable continuum model. The calculations were performed using the B3LYP functional and the 6-31G(d,p) basis set. The complete molecules were modelled, with no substitution of smaller groups on the periphery. In parallel, the compounds 2–5 were prepared by known or novel synthetic routes, to enable comparisons of experimental electronic absorption spectra with those calculated using time dependent-DFT at the same level of theory. As the ethane dimer 1 is not yet synthetically accessible, the model monomer meso-2-phenylethylZnTriPP was used for comparisons with the theoretical predictions. The results form a self-consistent set, enabling for the first time legitimate comparisons of the electronic structures of the series, especially regarding the degree to which the porphyrin p-systems interact by conjugation across the bridges. The theoretical calculations of the electronic transitions match the observed spectra in toluene to a remarkable degree, especially with respect to the peak maximum of the Q band, which represents to a large degree the energy of the HOMO–LUMO transition. The imine 4 is intrinsically polar due to the asymmetric bridge, and the HOMO is located almost exclusively on the ZnTriPP unit attached to the nitrogen of the imine, and the LUMO on the C-attached ring. Thus the Q-band transition is mapped as a comprehensive charge-transfer from the former ring to the latter. This may have consequences

  16. Structures of Ionic Liquids Dictate the Conversion and Selectivity of Enzymatic Glycerolysis: Theoretical Characterization by COSMO-RS

    DEFF Research Database (Denmark)

    Guo, Zheng

    2008-01-01

    Lipase-catalyzed glycerolysis of triolein has been examined using a group of tetraammonium-based ionic liquids (ILs) as media, specifically with functional groups in cation part. The results demonstrated that the reaction evolution and profile specificity of respective IL system could be quantita......Lipase-catalyzed glycerolysis of triolein has been examined using a group of tetraammonium-based ionic liquids (ILs) as media, specifically with functional groups in cation part. The results demonstrated that the reaction evolution and profile specificity of respective IL system could...... be quantitatively associated with the structural characteristics of the IL by means of quantum chemical and COSMO-RS calculation. Misfit interaction, Van der Waals interaction and chemical potential, etc. derived from COSMO-RS calculation are shown to be effective measures to delineate multiple interactions of ILs....... This might be of general value to help to understand the multiple solvation interaction among IL reaction systems at molecular level and promote the application of IL-mediated reactions to practical interests....

  17. Electronic structure and magnetism of layered compounds SrBO2 (B = Ni, Co, Mn): A theoretical investigation

    Science.gov (United States)

    Rahman, Mavlanjan; Zhou, Ke-Chao; Nie, Yao-Zhuang; Guo, Guang-Hua

    2017-10-01

    We investigate the electronic structure and magnetic properties of layered compounds SrBO2 (B = Co, Ni, Mn) based on first principles calculations in the framework of density functional theory with GGA+U method. We compute the phonon dispersion of these compounds to probe the dynamical stability and find that all the compounds are dynamically stable. SrCoO2 and SrNiO2 are G-type antiferromagnetic insulators, and SrMnO2 is an A-type antiferromagnetic conductor. The electronic configurations of 3d orbitals are (dxz)2(dz2)2(dyz)1(dxy)1(dx2-y2)1 and (dxz)2(dyz)2(dz2)2(dxy)1(dx2-y2)1 in SrCoO2 and SrNiO2, respectively. SrCoO2 shows a Jahn-Teller distortion (a>b) because the down-spin Co 3d electron occupies the degenerate (dxz, dyz) levels. Using Monte Carlo simulations based on the Heisenberg model with exchange parameters obtained from first principles calculations, we obtain the Néel temperatures (TN) of SrCoO2 and SrNiO2, which are 249 K and 85 K, respectively.

  18. A Theoretical Investigation of the Structure and Reactivity of the Molecular Constituents of Oil Sand and Oil Shale

    Energy Technology Data Exchange (ETDEWEB)

    Parish, Carol A. [Univ. of Richmond, VA (United States)

    2016-11-28

    2 reaction at three different sites on the 2-thienylmethyl radical. The addition is exothermic by 37 ~ 55 kcal mol-1 relative to the entrance channel. These excess energies are available to promote further decomposition or rearrangement of the adducts that lead to nascent products such as H, OH, H2O and CH2O. The reaction surfaces are characterized by relatively low barriers (most are lower than 10 kcal mol-1). Based upon a careful analysis of the overall barrier heights and reaction exothermicities, the formation of O2, OH and H2O is likely to be an important pathway in the radical recombination reactions of 2-thienylmethyl + HO2. This work was published in the Journal of Physical Chemistry A, 2011, 115, 14546-14557. REACTION OF THIOPHENE AND METHYLTHIOPHENE WITH SINGLET AND TRIPLET MOLECULAR OXYGEN Mechanisms for the reaction of thiophene and 2-methylthiophene with molecular oxygen on both the triplet and singlet potential energy surfaces (PESs) were investigated using ab initio methods. Thiophene and 2-methylthiophene where shown to react with O2 via two types of mechanisms; namely, direct hydrogen abstraction and addition/elimination. The barriers for reaction with triplet oxygen are all significantly large (i.e., > 30 kcal mol-1), which indicates that the direct oxidation of thiophene by ground state oxygen might be important only in high temperature processes. Reaction of thiophene with singlet oxygen via a 2+4 cycloaddition leading to endoperoxides is the most favorable channel. Moreover, it was found that alkylation of the thiophene ring (i.e., methyl-substituted thiophene) is capable of lowering the barrier height for the addition pathway. The implication of the current theoretical results may shed new light on the initiation mechanisms for combustion of asphaltenes. This work was published in the Journal of Physical Chemistry A, 2012 116, 4934-4946. JAHN-TELLER STABILIZATION IN POSS CATIONS We have a long

  19. Theoretical molecular structure, vibrational frequencies and NMR investigations of 2-[(1E-2-aza-2-(5-methyl(2-pyridylethenyl]-4-bromobenzen-1-ol

    Directory of Open Access Journals (Sweden)

    Cemal Parlak

    2012-08-01

    Full Text Available The normal mode frequencies and corresponding vibrational assignments, 1H and 13C NMR chemical shifts and structural parameters (bond lengths, bond and dihedral angles of 2-[(1E-2-aza-2-(5-methyl(2-pyridylethenyl]-4-bromobenzen-1-ol (2mpe-4bb Schiff base compound have been theoretically examined by means of Hartree-Fock (HF and Becke-3-Lee-Yang-Parr (B3LYP density functional methods with 6-31G(d and 6-311++G(d,p basis sets. Furthermore, reliable vibrational assignments have made on the basis of potential energy distribution (PED calculated and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO of 2mpe-4bb have been predicted. Theoretical results have been successfully compared with available experimental data in the literature. Regarding the calculations, 2mpe-4bb prefers enol-imine form and DFT method is superior to HF approach except for predicting bond lengths.DOI: http://dx.doi.org/10.4314/bcse.v26i2.11

  20. Internal photoemission for photovoltaic using p-type Schottky barrier: Band structure dependence and theoretical efficiency limits

    Science.gov (United States)

    Shih, Ko-Han; Chang, Yin-Jung

    2018-01-01

    Solar energy conversion via internal photoemission (IPE) across a planar p-type Schottky junction is quantified for aluminum (Al) and copper (Cu) in the framework of direct transitions with non-constant matrix elements. Transition probabilities and k-resolved group velocities are obtained based on pseudo-wavefunction expansions and realistic band structures using the pseudopotential method. The k-resolved number of direct transitions, hole photocurrent density, quantum yield (QY), and the power conversion efficiency (PCE) under AM1.5G solar irradiance are subsequently calculated and analyzed. For Al, the parabolic and "parallel-band" effect along the U-W-K path significantly enhances the transition rate with final energies of holes mainly within 1.41 eV below the Fermi energy. For Cu, d-state hot holes mostly generated near the upper edge of 3d bands dominate the hole photocurrent and are weekly (strongly) dependent on the barrier height (metal film thickness). Hot holes produced in the 4s band behave just oppositely to their d-state counterparts. Non-constant matrix elements are shown to be necessary for calculations of transitions due to time-harmonic perturbation in Cu. Compared with Cu, Al-based IPE in p-type Schottky shows the highest PCE (QY) up to about 0.2673% (5.2410%) at ΦB = 0.95 eV (0.5 eV) and a film thickness of 11 nm (20 nm). It is predicted that metals with relatively dispersionless d bands (such as Cu) in most cases do not outperform metals with photon-accessible parallel bands (such as Al) in photon energy conversion using a planar p-type Schottky junction.

  1. Confirming the theoretical structure of expert-developed text messages to improve adherence to anti-hypertensive medications

    Science.gov (United States)

    Farris, Karen B; Salgado, Teresa M; Batra, Peter; Piette, John D.; Singh, Satinder; Guhad, Ahmed; Newman, Sean; Marshall, Vincent D.; An, Larry

    2015-01-01

    Background Text messages can improve medication adherence and outcomes in several conditions. For this study, experts developed text messages addressing determinants of medication adherence: disease beliefs, medication necessity, medication concerns, and forgetfulness, as well as positive reinforcement messages for patients who were adherent. Objectives To validate expert-developed text messages to address medication non-adherence with a group of non-researchers. Methods A two-wave, card-sorting activity was conducted with students and staff at the University of Michigan. In the first wave, 40 participants grouped 32 messages addressing barriers for medication adherence (disease beliefs, medication necessity, medication concerns, and forgetfulness) according to their perceived relationship. Messages with poor grouping agreement were deleted or modified. In the second wave, positive reinforcement messages were developed and tested along with the previous categories (36 messages) by 37 participants. Similarity and cluster analyses were used to assess agreement between experts and participants. Results In the first card-sorting wave, participants grouped messages into between 2 and 13 separate categories. Similarity analysis showed four groupings of messages, however, some had an agreement below 50% and clusters appeared dispersed. In the second wave, and after messages being edited, participants grouped the messages into between 4 and 9 categories. Five groups (now including positive reinforcement messages) were identified with higher agreement in the similarity and cluster analyses. Conclusions The structure of expert-developed text messages to address medication adherence key barriers was confirmed. Messages will be used in future research to determine their impact on affecting medication adherence to anti-hypertensive medications using a reinforcement learning controlled text messaging service. PMID:26525857

  2. A theoretical investigation of the structural and electronic properties of 55-atom nanoclusters: The examples of Y–Tc and Pt

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Krys E. A.; Piotrowski, Maurício J., E-mail: mauriciomjp@gmail.com [Department of Physics, Federal University of Pelotas, P.O. Box 354, 96010 − 900, Pelotas, RS (Brazil); Chaves, Anderson S.; Da Silva, Juarez L. F., E-mail: juarez-dasilva@iqsc.usp.br [São Carlos Institute of Chemistry, University of São Paulo, P.O. Box 780, 13560 − 970, São Carlos, SP (Brazil)

    2016-02-07

    Several studies have found that the Pt{sub 55} nanocluster adopts a distorted reduced core structure, DRC{sub 55}, in which there are 8–11 atoms in the core and 47–44 atoms in the surface, instead of the compact and high-symmetry icosahedron structure, ICO{sub 55}, with 13 and 42 atoms in the core and surface, respectively. The DRC structure has also been obtained as the putative global minimum configuration (GMC) for the Zn{sub 55} (3d), Cd{sub 55} (4d), and Au{sub 55} (5d) systems. Thus, the DRC{sub 55} structure has been reported only for systems with a large occupation of the d-states, where the effects of the occupation of the valence anti-bonding d-states might play an important role. Can we observe the DRC structure for 55-atom transition-metal systems with non-occupation of the anti-bonding d-states? To address this question, we performed a theoretical investigation of the Y {sub 55}, Zr{sub 55}, Nb{sub 55}, Mo{sub 55}, Tc{sub 55}, and Pt{sub 55} nanoclusters, employing density functional theory calculations. For the putative GMCs, we found that the Y {sub 55} adopts the ICO{sub 55} structure, while Nb{sub 55} and Mo{sub 55} adopt a bulk-like fragment based on the hexagonal close-packed structure and Tc{sub 55} adopts a face-centered cubic fragment; however, Zr{sub 55} adopts a DRC{sub 55} structure, like Zn{sub 55}, Cd{sub 55}, Pt{sub 55}, and Au{sub 55}. Thus we can conclude that the preference for DRC{sub 55} structure is not related to the occupation of the anti-bonding d-states, but to a different effect, in fact, a combination of structural and electronic effects. Furthermore, we obtained that the binding energy per atom follows the occupation of the bonding and anti-bonding model, i.e., the stability of the studied systems increases from Y to Tc with a small oscillation for Mo, which also explains the equilibrium bond lengths. We obtained a larger magnetic moment for Y {sub 55} (31 μ{sub B}) which can be explained by the localization of the d

  3. A theoretical investigation of the structural and electronic properties of 55-atom nanoclusters: The examples of Y-Tc and Pt.

    Science.gov (United States)

    Batista, Krys E A; Piotrowski, Maurício J; Chaves, Anderson S; Da Silva, Juarez L F

    2016-02-07

    Several studies have found that the Pt55 nanocluster adopts a distorted reduced core structure, DRC55, in which there are 8-11 atoms in the core and 47-44 atoms in the surface, instead of the compact and high-symmetry icosahedron structure, ICO55, with 13 and 42 atoms in the core and surface, respectively. The DRC structure has also been obtained as the putative global minimum configuration (GMC) for the Zn55 (3d), Cd55 (4d), and Au55 (5d) systems. Thus, the DRC55 structure has been reported only for systems with a large occupation of the d-states, where the effects of the occupation of the valence anti-bonding d-states might play an important role. Can we observe the DRC structure for 55-atom transition-metal systems with non-occupation of the anti-bonding d-states? To address this question, we performed a theoretical investigation of the Y 55, Zr55, Nb55, Mo55, Tc55, and Pt55 nanoclusters, employing density functional theory calculations. For the putative GMCs, we found that the Y 55 adopts the ICO55 structure, while Nb55 and Mo55 adopt a bulk-like fragment based on the hexagonal close-packed structure and Tc55 adopts a face-centered cubic fragment; however, Zr55 adopts a DRC55 structure, like Zn55, Cd55, Pt55, and Au55. Thus we can conclude that the preference for DRC55 structure is not related to the occupation of the anti-bonding d-states, but to a different effect, in fact, a combination of structural and electronic effects. Furthermore, we obtained that the binding energy per atom follows the occupation of the bonding and anti-bonding model, i.e., the stability of the studied systems increases from Y to Tc with a small oscillation for Mo, which also explains the equilibrium bond lengths. We obtained a larger magnetic moment for Y 55 (31 μB) which can be explained by the localization of the d-states in Y at nanoscale, which is not observed for the remaining systems (0-1 μB).

  4. On the structure of transition metals complexes with the new tridentate dye of thiazole series: Theoretical and experimental studies

    Science.gov (United States)

    Fizer, Maksym; Sidey, Vasyl; Tupys, Andrii; Ostapiuk, Yurii; Tymoshuk, Oleksandr; Bazel, Yaroslav

    2017-12-01

    The 1-[(5-Benzyl-1,3-thiazol-2-yl)diazenyl]naphthalene-2-ol (BnTAN) is a recently synthesized azo dye that can act as a tridentate ligand in complexes with transition metals. In a series of previous works, this analytical reagent was shown to be applicable for selective, reliable, express and relatively inexpensive determination of heavy metals in different objects through the spectrophotometric technique. Although the action of 1-(2-thiazolylazo)-2-naphthol (TAN) dyes as tridentate ligands has been suggested in the literature long time ago, due to the lack of experimental data, it was necessary to investigate the mechanism of formation and the structure of BnTAN complexes with the such transition metals as Cu(II), Zn(II) and Cd(II). Furthermore, the reactivity and properties of different acidity forms and conformers of BnTAN and related TAN dyes were not fully defined, so the determination of these properties by analysis of wavefunction was also necessary. Two standard spectrophotometric methods and voltammetric technique were used to determine the composition of complex of BnTAN with metals ions. All three experimental methods indicate that coordination ratio of metal:dye is equal to 1:2. Moreover, this study reports the stability and geometry of conformers of different forms (anionic/neutral/cationic) of BnTAN, along with a detailed analysis of electronic properties, reactivity and aromaticity of the most stable conformers of BnTAN forms. Each of the above forms has some difference in position of benzyl ring against the thiazole moiety, which is explained in terms of attraction and repulsion of these two fragments induced by partial atomic charges. The crucial influence of hydrogen bond and weak non-covalent interactions between naphthyl, aza- and thiazolyl fragments has been established. The quantum chemical calculations have shown that partial atomic charges of anionic, neutral and cationic forms can explain the reactivity of each BnTAN form, and have also

  5. Synthesis, geometry optimization, spectroscopic investigations (UV/Vis, excited states, FT-IR) and application of new azomethine dyes

    Science.gov (United States)

    Shahab, Siyamak; Sheikhi, Masoome; Filippovich, Liudmila; Kumar, Rakesh; Dikusar, Evgenij; Yahyaei, Hooriye; Khaleghian, Mehrnoosh

    2017-11-01

    In the present work, the quantum theoretical calculations of the molecular structures of the four new synthesized azomethine dyes such as: (E)-N-(4-butoxybenzylidene)-4-((E)-phenyldiazenyl)aniline (PAZB-6), (E)-N-(4-(benzyloxy)benzylidene)-4-((E))-phenyldiazenyl)aniline (PAZB-7), 4-((E)-4-((E)-phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-8), (E)-N-(4-methoxybenzylidene)-4-((E))-phenyldiazenyl)aniline (PAZB-9) have been predicted using Density Functional Theory in the solvent Dimethylformamide. The geometries of the azomethine dyes were optimized by PBE1PBE/6-31+G* level of theory. The electronic spectra of the title compounds in the solvent DMF was carried out by TDPBE1PBE/6-31+G* method. FT-IR spectra of the title compounds are recorded and discussed. Frontier molecular orbitals, molecular electrostatic potential, electronic properties, natural charges and Natural Bond Orbital (NBO) analysis of the mentioned compounds were investigated and discussed by theoretical calculations. The azomethine dyes were synthesized after quantum chemical modeling for optical applications. A new study of anisotropy of thermal and electrical conductivity of the colored stretched PVA-films have been undertaken.

  6. Theoretical studies of the local structures and spin Hamiltonian parameters for Cu2+ in alkaline earth alumino borate glasses

    Science.gov (United States)

    Guo, Jia-Xing; Wu, Shao-Yi; Kuang, Min-Quan; Peng, Li; Wu, Li-Na

    2018-01-01

    The local structures and spin Hamiltonian parameters are theoretically studied for Cu2+ in alkaline earth alumino borate (XAB, X = Mg, Ca and Sr) glasses by using the perturbation calculations for tetragonally elongated octahedral 3d9 groups. The [CuO6]10‑ groups are subject to the large relative tetragonal elongation ratios of 15.4%, 13.4% and 13.0% for MgAB, CaAB and SrAB glasses, respectively, arising from the Jahn-Teller effect. The decreasing cubic field parameter Dq, orbital reduction factor k and relative elongation ratio with the increase of the radius of alkaline earth ion X from Mg to Ca or Sr are analyzed for the studied systems in a uniform way.

  7. Structure, spectroscopic analyses (FT-IR and NMR), vibrational study, chemical reactivity and molecular docking study on 3,3'-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione), a promising anticancerous bis-lawsone derivative

    Science.gov (United States)

    Yadav, Krishna Kant; Kumar, Abhishek; Kumar, Amarendra; Misra, Neeraj; Brahmachari, Goutam

    2018-02-01

    Lawsone (2-hydroxy-1,4-naphthoquinone)has been evaluated to possess a wide range of biological and pharmacological activities. The interesting structural pattern of lawsone coupled with its so-called multifaceted pharmacological potential have made this scaffolds useful in certain chemical processes, particularly in synthesizing ligands for metal complexations, and also few of its derivatives have shown a number of biological activities. The equilibrium geometry of 3,3‧-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione) (1; TPMHD), a promising anticancerous lawsone derivative, has been determined and analyzed at DFT method employingB3LYP/6-311++G(d,p) level of theory. The reactivity descriptors such as Fukui functions and HOMO-LUMO gap are calculated and discussed. The infrared spectra of TPMHD(1) are calculated and compared with the experimentally observed ones. Moreover, 1H and 13C NMR spectra have been calculated by using the gauge independent atomic orbital method. The docking studies reveal that the TPMHD has strong binding affinity toward target protein 2SHP. Thus the compound has a possible use as a drug in cancer therapy. The study suggests further investigation on TPMHD for their in-depth biological and pharmaceutical importance.

  8. BET, thermal degradation, and FTIR spectras of triazine polyamine polymers.

    Science.gov (United States)

    Can, Mustafa

    2017-04-01

    Here we show effect of the polyamine polymer chain length to BET isotherms. According to IUPAC classification [1], all three polymers are fitting type 1 physical adsorption isotherm with H3 hysteresis (except for EDA having H2 hysteresis). Moreover, TG and TGA analysis of polymers triazine-ethylenediamine (EDA) and triazine-triethylenetetramine (TETA) are provided. Due to the similarities of the structure, main decomposition temperatures are close to each other (between 593 K and 873 K). In order to understand change of FTIR spectra with adsorption and stripping Au(III), fresh, Au(III) adsorbed and recycled spectras of polymers measured. For further discussions about the effect of chain length to adsorption of Au(III) onto triazine polyamine polymer particles "Au (III) Uptake by Triazine Polyamine Polymers: Mechanism, Kinetic and Equilibrium Studies" Can et al. [2] (article in press).

  9. Effect of the methanol molecule on the stabilization of C₁₈H₁₈O₄ crystal: combined theoretical and structural investigation.

    Science.gov (United States)

    Sallum, Lóide O; Napolitano, Hamilton B; Carvalho, Paulo de Sousa; Cidade, Amanda Feitosa; de Aquino, Gilberto Lucio Benedito; Coutinho, Nayara D; Camargo, Ademir J; Ellena, Javier; de Oliveira, Heibbe C B; Silva, Valter H C

    2014-10-30

    The ability of the chalcone, C18H18O4, to form solvates was theoretically and experimentally investigated. The unit cell with Z' > 1, composed of two independent chalcone molecules (α and β), shows the formation of a stable molecular complex which is related with the presence of methanol in this crystal lattice. Aiming to understand the process of crystal lattice stabilization, a combination of techniques was used, including X-ray diffraction (XRD), computational molecular modeling, and an ab initio molecular dynamic. The results show that α and β molecules are sterically barred from forming a direct hydrogen bond with one other. In addition, the presence of the methanol molecule stabilizes the crystal structure by a bifurcated O-H···O interaction acting as a bridge between them. The theoretical thermodynamic parameter and the rigid potential energy surface scan describe the role of methanol in the energy stabilization of the crystal. The absence of the methanol compound in the asymmetric unit destabilizes the crystalline structure, making the formation process of the asymmetric unit nonspontaneous. The energy difference between α and β molecules is around 0.80 kcal·mol(-1), indicating that both are stable and equally possible in the crystal lattice. The analysis of the energy profile of the C14-O2···H1-O3 and O2-H1···O3-C17 torsion angles in the crystal packing shows that the α and β molecules are confined in the stable potential region, in agreement with the two conformers in the asymmetric unit. The Molecular Electrostatic Potential (MEP) shows that the methanol has no steric effects, which prevents small motion around the torsion angles.

  10. Theoretical geodesy

    Directory of Open Access Journals (Sweden)

    Borkowski Andrzej

    2015-12-01

    Full Text Available The paper presents a summary of research activities concerning theoretical geodesy performed in Poland in the period of 2011-2014. It contains the results of research on new methods of the parameter estimation, a study on robustness properties of the M-estimation, control network and deformation analysis, and geodetic time series analysis. The main achievements in the geodetic parameter estimation involve a new model of the M-estimation with probabilistic models of geodetic observations, a new Shift-Msplit estimation, which allows to estimate a vector of parameter differences and the Shift-Msplit(+ that is a generalisation of Shift-Msplit estimation if the design matrix A of a functional model has not a full column rank. The new algorithms of the coordinates conversion between the Cartesian and geodetic coordinates, both on the rotational and triaxial ellipsoid can be mentioned as a highlights of the research of the last four years. New parameter estimation models developed have been adopted and successfully applied to the control network and deformation analysis.

  11. FT-IR SOLUTION SPECTRA OF PROPYL SULFIDE, PROPYL SULFOXIDE, AND PROPYL SULFONE

    Science.gov (United States)

    FT-IR spectra were obtained of 0.5% volumetric solutions of propyl sulfide, propyl sulfoxide, and propyl sulfone in hexane, CCl4, CS2, and CHCl3 to assist in the assignment of FT-IR-PAS spectra of propyl sulfoxide sorbed within the structure of several peats and onto cellulose. T...

  12. Kvantitativní FTIR spektrometrie huminových látek

    Czech Academy of Sciences Publication Activity Database

    Novák, F.; Machovič, Vladimír; Hrabalová, H.; Novotná, M.

    2017-01-01

    Roč. 111, č. 6 (2017), s. 363-373 ISSN 0009-2770 Institutional support: RVO:67985891 Keywords : FTIR * humic substances * infrared-spectroscopy * structure Subject RIV: DD - Geochemistry OBOR OECD: Analytical chemistry Impact factor: 0.387, year: 2016

  13. Theoretical investigations of the spin-Hamiltonian parameters and local structural distortion of Fe(3+): ZnAl2O4 crystals.

    Science.gov (United States)

    Yang, Zi-Yuan

    2014-10-15

    The relations between the spin-Hamiltonian (SH) parameters and the structural parameters of the Fe(3+) ions in Fe(3+): ZnAl2O4 crystals have been established by means of the microscopic spin Hamiltonian theory and the superposition model (SPM). On the basis of this, the local structure distortion, the second-order zero-field splitting (ZFS) parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors g factors: g//, g⊥, and Δg(=g//-g⊥) for Fe(3+) ions in Fe(3+): ZnAl2O4 crystals, for the first time taking into account the electronic magnetic interactions, i.e. the spin-spin (SS), the spin-other-orbit (SOO), and the orbit-orbit (OO) interactions, besides the well-known spin-orbit (SO) interaction, are theoretically investigated using complete diagonalization method (CDM). This investigation reveals that the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe(3+) ions in Fe(3+): ZnAl2O4 crystals. The theoretical second-order ZFS parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors: g//, g⊥, and Δg of the ground state for Fe(3+) ion in Fe(3+): ZnAl2O4 crystals yield a good agreement with experiment findings by taking into account the lattice distortions: ΔR=0.0191nm and Δθ=0.076°. In conclusion, our research shows that there is a slight local structure distortion for Fe(3+) ions in Fe(3+): ZnAl2O4 crystals, but the site of Fe(3+) still retains D3d symmetry. On the other hand, it is found for Fe(3+) ions in Fe(3+): ZnAl2O4 crystals that the SO mechanism is the most important one, whereas the contributions to the SH parameters from other four mechanisms, including the SS, SOO, OO, and SO∼SS∼SOO∼OO mechanisms are not appreciable, especially for the ZFS parameter D. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Tailoring characteristic thermal stability of Ni-Au binary nanocrystals via structure and composition engineering: theoretical insights into structural evolution and atomic inter-diffusion

    Directory of Open Access Journals (Sweden)

    Bangquan Li

    2014-11-01

    Full Text Available We report on the structural evolution and atomic inter-diffusion characteristics of the bimetallic Ni-Au nanocrystals (NCs by molecular dynamics simulations studies. Our results reveal that the thermal stability dynamics of Ni-Au NCs strongly depends on the atomic configurations. By engineering the structural construction with Ni:Au = 1:1 atomic composition, compared with core-shell Au@Ni and alloy NCs, the melting point of core-shell Ni@Au NCs is significantly enhanced up to 1215 K. Unexpectedly, with atomic ratio of Au:Ni= 1:9, the melting process initiates from the atoms in the shell of Ni@Au and alloy NCs, while starts from the core of Au@Ni NCs. The corresponding features and evolution process of structural motifs, mixing and segregation are illustrated via a series of dynamic simulations videos. Moreover, our results revealed that the face centered cubic phase Au0.75Ni0.25 favorably stabilizes in NCs form but does not exist in the bulk counterpart, which elucidates the anomalies of previously reported experimental results on such bimetallic NCs.

  15. An FT-Raman, FT-IR, and Quantum Chemical Investigation of Stanozolol and Oxandrolone

    Directory of Open Access Journals (Sweden)

    Tibebe Lemma

    2017-12-01

    Full Text Available We have studied the Fourier Transform Infrared (FT-IR and the Fourier transform Raman (FT-Raman spectra of stanozolol and oxandrolone, and we have performed quantum chemical calculations based on the density functional theory (DFT with a B3LYP/6-31G (d, p level of theory. The FT-IR and FT-Raman spectra were collected in a solid phase. The consistency between the calculated and experimental FT-IR and FT-Raman data indicates that the B3LYP/6-31G (d, p can generate reliable geometry and related properties of the title compounds. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution. The good agreement between the experimental and theoretical spectra allowed positive assignment of the observed vibrational absorption bands. Finally, the calculation results were applied to simulate the Raman and IR spectra of the title compounds, which show agreement with the observed spectra.

  16. DNA Infrared Absorbency Detection using Photopyroelectric Technique and FTIR Spectroscopy

    OpenAIRE

    Ebu-TEİR, Musa; Abu-TAHA, Mohammad; Al-JAMAL, Atef; EİDEH, H.

    2008-01-01

    Absorbencies of different DNA samples were studied using the well known photopyroelectric (PPE) technique and Fourier Transform Infrared (FTIR) spectrometer. In the fi rst method, wideband radiation absorbance from an infrared (IR) pulsed wideband source (PWBS) by DNA samples were detected and compared with FTIR spectrum. It was shown that the PPE technique results are useful and comparable to FTIR in distinguishing different DNA samples of biological interests

  17. On the Electronic Structures and Electron Affinities of the m- Benzoquinone (BQ) Diradical and the o-, p-BQ Molecules: A Synergetic Photoelectron Spectroscopic and Theoretical Study

    International Nuclear Information System (INIS)

    Fu, Qiang; Yang, Jinlong; Wang, Xue B.

    2011-01-01

    Electron affinities (EAs) and electronic structures of benzoquinone molecules (BQs) play a vital role in a wide range of applications involving these molecules from biological photosynthesis to energy conversion processes. In this article, we report a systematic spectroscopic probe on the electronic structures and EAs of all three isomers (o-, m-, and p-BQs) employing photodetachment photoelectron spectroscopy (PES) and ab initio electronic structure calculations. PES spectra of three radical anions (BQ(lg b ullet)-) were taken with different photon energies and at low temperature in order to accurately determine the EAs and probe ground as well as the excited states of the corresponding neutral molecules. Similar spectral pattern was observed in the o- and p-BQ(lg b ullet)- spectra, each revealing a broad ground state feature and a large band gap, followed by well-resolved excited states peaks. The EAs of o- and p-BQ are determined to be 1.90, 1.85 eV, and singlet-triplet band gaps to be 1.68, and 2.32 eV, respectively. In contrast, the spectrum of m-BQ(lg b ullet)- is distinctly different from its two congeners, with no clear band gap and a much higher EA (2.89 eV). Accompanying theoretical calculations confirm experimental EAs and band gaps, and further unravel a triplet ground state for m-BQ in contrast to singlet ground states for o- and p- isomers. The diradical nature of m-BQ, consistent with its non-Kekule structure, is primarily responsible for the observed high EA and also explains its nonexistence in bulk materials.

  18. Theoretical Mechanics Theoretical Physics 1

    CERN Document Server

    Dreizler, Reiner M

    2011-01-01

    After an introduction to basic concepts of mechanics more advanced topics build the major part of this book. Interspersed is a discussion of selected problems of motion. This is followed by a concise treatment of the Lagrangian and the Hamiltonian formulation of mechanics, as well as a brief excursion on chaotic motion. The last chapter deals with applications of the Lagrangian formulation to specific systems (coupled oscillators, rotating coordinate systems, rigid bodies). The level of this textbook is advanced undergraduate. The authors combine teaching experience of more than 40 years in all fields of Theoretical Physics and related mathematical disciplines and thorough knowledge in creating advanced eLearning content. The text is accompanied by an extensive collection of online material, in which the possibilities of the electronic medium are fully exploited, e.g. in the form of applets, 2D- and 3D-animations. - A collection of 74 problems with detailed step-by-step guidance towards the solutions. - A col...

  19. Single crystal structures and theoretical calculations of uranium endohedral metallofullerenes (U@C2n , 2n = 74, 82) show cage isomer dependent oxidation states for U.

    Science.gov (United States)

    Cai, Wenting; Morales-Martínez, Roser; Zhang, Xingxing; Najera, Daniel; Romero, Elkin L; Metta-Magaña, Alejandro; Rodríguez-Fortea, Antonio; Fortier, Skye; Chen, Ning; Poblet, Josep M; Echegoyen, Luis

    2017-08-01

    Charge transfer is a general phenomenon observed for all endohedral mono-metallofullerenes. Since the detection of the first endohedral metallofullerene (EMF), La@C 82 , in 1991, it has always been observed that the oxidation state of a given encapsulated metal is always the same, regardless of the cage size. No crystallographic data exist for any early actinide endohedrals and little is known about the oxidation states for the few compounds that have been reported. Here we report the X-ray structures of three uranium metallofullerenes, U@ D 3h -C 74 , U@ C 2 (5)-C 82 and U@ C 2v (9)-C 82 , and provide theoretical evidence for cage isomer dependent charge transfer states for U. Results from DFT calculations show that U@ D 3h -C 74 and U@ C 2 (5)-C 82 have tetravalent electronic configurations corresponding to U 4+ @ D 3h -C 74 4- and U 4+ @ C 2 (5)-C 82 4- . Surprisingly, the isomeric U@ C 2v (9)-C 82 has a trivalent electronic configuration corresponding to U 3+ @ C 2v (9)-C 82 3- . These are the first X-ray crystallographic structures of uranium EMFs and this is first observation of metal oxidation state dependence on carbon cage isomerism for mono-EMFs.

  20. Drift and transmission FT-IR spectroscopy of forest soils: an approach to determine decomposition processes of forest litter

    International Nuclear Information System (INIS)

    Haberhauer, G.; Gerzabek, M.H.

    1999-06-01

    A method is described to characterize organic soil layers using Fourier transformed infrared spectroscopy. The applicability of FT-IR, either dispersive or transmission, to investigate decomposition processes of spruce litter in soil originating from three different forest sites in two climatic regions was studied. Spectral information of transmission and diffuse reflection FT-IR spectra was analyzed and compared. For data evaluation Kubelka Munk (KM) transformation was applied to the DRIFT spectra. Sample preparation for DRIFT is simpler and less time consuming in comparison to transmission FT-IR, which uses KBr pellets. A variety of bands characteristics of molecular structures and functional groups has been identified for these complex samples. Analysis of both transmission FT-IR and DRIFT, showed that the intensity of distinct bands is a measure of the decomposition of forest litter. Interferences due to water adsorption spectra were reduced by DRIFT measurement in comparison to transmission FT-IR spectroscopy. However, data analysis revealed that intensity changes of several bands of DRIFT and transmission FT-IR were significantly correlated with soil horizons. The application of regression models enables identification and differentiation of organic forest soil horizons and allows to determine the decomposition status of soil organic matter in distinct layers. On the basis of the data presented in this study, it may be concluded that FT-IR spectroscopy is a powerful tool for the investigation of decomposition dynamics in forest soils. (author)

  1. Evaluation of polybutadiene rubbers using FTIR spectra

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, L.N.; Schimidt, F., E-mail: lucas@ifg.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFG), Goiania, GO (Brazil); Antonio, P.L.; Caldas, L.V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vieira, S.L. [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Instituto de Fisica

    2017-09-01

    Radiation dosimetry for medical and industrial purposes has increasingly evolved over the last few decades with the introduction of various new detectors. Depending on the properties exhibited for radiation dosimetry, some detectors present their applications in a specific area. From a physics point of view, an ideal dosimeter should be able to measure absorbed dose. In this work, synthetic materials based on polybutadiene rubbers (PBR) were proposed as a new class of radiation detectors. The influence of radiation dose on their properties has been investigated for application in radiation dosimetry. The rubber samples were exposed to absorbed doses from 10 Gy up to 250 Gy, using a {sup 60}Co Gamma Cell-220 system. Their responses were carried out with a Fourier Transform Infrared (FTIR) Spectrometer to investigate the presence of absorbance peaks. The results suggested the existence of a relationship between the absorbed doses and the absorbance peaks associated with stretching (1300-1200 cm{sup -1}), deformation (1450-1340 cm{sup -1}) and vibration (1500-1400 cm{sup -1}) processes in the material. (author)

  2. Gas monitoring onboard ISS using FTIR spectroscopy

    Science.gov (United States)

    Gisi, Michael; Stettner, Armin; Seurig, Roland; Honne, Atle; Witt, Johannes; Rebeyre, Pierre

    2017-06-01

    In the confined, enclosed environment of a spacecraft, the air quality must be monitored continuously in order to safeguard the crew's health. For this reason, OHB builds the ANITA2 (Analysing Interferometer for Ambient Air) technology demonstrator for trace gas monitoring onboard the International Space Station (ISS). The measurement principle of ANITA2 is based on the Fourier Transform Infrared (FTIR) technology with dedicated gas analysis software from the Norwegian partner SINTEF. This combination proved to provide high sensitivity, accuracy and precision for parallel measurements of 33 trace gases simultaneously onboard ISS by the precursor instrument ANITA1. The paper gives a technical overview about the opto-mechanical components of ANITA2, such as the interferometer, the reference Laser, the infrared source and the gas cell design and a quick overview about the gas analysis. ANITA2 is very well suited for measuring gas concentrations specifically but not limited to usage onboard spacecraft, as no consumables are required and measurements are performed autonomously. ANITA2 is a programme under the contract of the European Space Agency, and the air quality monitoring system is a stepping stone into the future, as a precursor system for manned exploration missions.

  3. Evaluation of polybutadiene rubbers using FTIR spectra

    International Nuclear Information System (INIS)

    Oliveira, L.N.; Schimidt, F.; Antonio, P.L.; Caldas, L.V.E.; Vieira, S.L.

    2017-01-01

    Radiation dosimetry for medical and industrial purposes has increasingly evolved over the last few decades with the introduction of various new detectors. Depending on the properties exhibited for radiation dosimetry, some detectors present their applications in a specific area. From a physics point of view, an ideal dosimeter should be able to measure absorbed dose. In this work, synthetic materials based on polybutadiene rubbers (PBR) were proposed as a new class of radiation detectors. The influence of radiation dose on their properties has been investigated for application in radiation dosimetry. The rubber samples were exposed to absorbed doses from 10 Gy up to 250 Gy, using a 60 Co Gamma Cell-220 system. Their responses were carried out with a Fourier Transform Infrared (FTIR) Spectrometer to investigate the presence of absorbance peaks. The results suggested the existence of a relationship between the absorbed doses and the absorbance peaks associated with stretching (1300-1200 cm -1 ), deformation (1450-1340 cm -1 ) and vibration (1500-1400 cm -1 ) processes in the material. (author)

  4. FTIR investigation into Degradation of Natural Rubber

    Science.gov (United States)

    Rich, Ryan; Waldek Zerda, T.

    2006-10-01

    The aging of tires is of the highest concerns to the automotive industry, due to its implications in fuel economy and automobile safety. Previously, the high absorption rate of carbon black filled polymers has hindered the use of Fourier Transform Infrared Spectroscopy (FTIR) in studying this occurrence. However, recent developments in attenuated total reflection (ATR) techniques have provided a means for spectroscopically monitoring the composition changes induced in rubber blends by heat, exposure to ultra-violet radiation, and mechanical strain. The ATR apparatus, employing a germanium crystal, collected high quality infrared spectra at a reduced penetration depth of less than one micron. This research analyzed natural polymer blends with varied aggregate size and concentration of carbon black. The samples were analyzed as a function of exposure time to 70 C heat and UV radiation, as well elongation by mechanical strain. In these spectra, growth of the 1740cm-1 peak is assigned to increase populations of the C=O band. Carbon black filler rubber is shown to slow the rate of oxidation in pure natural rubber. Crystallization of rubber composites under strain is characterized by changes in the shapes of the CH stretch bands.

  5. 3. Theoretical Physics Division

    International Nuclear Information System (INIS)

    For the period September 1980 - Aug 1981, the studies in theoretical physics divisions have been compiled under the following headings: in nuclear physics, nuclear structure, nuclear reactions and intermediate energies; in particle physics, NN and NantiN interactions, dual topological unitarization, quark model and quantum chromodynamics, classical and quantum field theories, non linear integrable equations and topological preons and Grand unified theories. A list of publications, lectures and meetings is included [fr

  6. Investigating the long-term evolution of subtropical ozone profiles applying ground-based FTIR spectrometry

    Directory of Open Access Journals (Sweden)

    O. E. García

    2012-11-01

    Full Text Available This study investigates the long-term evolution of subtropical ozone profile time series (1999–2010 obtained from ground-based FTIR (Fourier Transform InfraRed spectrometry at the Izaña Observatory ozone super-site. Different ozone retrieval strategies are examined, analysing the influence of an additional temperature retrieval and different constraints. The theoretical assessment reveals that the FTIR system is able to resolve four independent ozone layers with a precision of better than 6% in the troposphere and of better than 3% in the lower, middle and upper stratosphere. This total error includes the smoothing error, which dominates the random error budget. Furthermore, we estimate that the measurement noise as well as uncertainties in the applied atmospheric temperature profiles and instrumental line shape are leading error sources. We show that a simultaneous temperature retrieval can significantly reduce the total random errors and that a regular determination of the instrumental line shape is important for producing a consistent long-term dataset. These theoretical precision estimates are empirically confirmed by daily intercomparisons with Electro Chemical Cell (ECC sonde profiles. In order to empirically document the long-term stability of the FTIR ozone profile data we compare the linear trends and seasonal cycles as obtained from the FTIR and ECC time series. Concerning seasonality, in winter both techniques observe stratospheric ozone profiles that are typical middle latitude profiles (low tropopause, low ozone maximum concentrations and in summer/autumn profiles that are typical tropical profiles (high tropopause, high maximum concentrations. The linear trends estimated from the FTIR and the ECC datasets agree within their error bars. For the FTIR time series, we observe a significant negative trend in the upper troposphere/lower stratosphere of about −0.2% yr−1 and a significant positive trend in the middle and

  7. Spectroscopic studies, theoretical models and structural characterization. II. Synthesis and X-ray powder diffraction of the elpasolites Cs2NaSmCl6

    International Nuclear Information System (INIS)

    Poblete, V.; Acevedo, R.

    1998-01-01

    In this research work, we report the synthesis and structural characterization of the stoichiometric elpasolite Cs 2 NaSmCl 6 . The synthesis was performed under a solid state reaction in nitrogen atmosphere from the chemicals CsCl, NaCl and SmCl 3 weighted stoichiometrically. The best possible crystallization temperature was obtained using thermal studies of the type DTA/TGA (the thermal treatment was allowed to proceed for 2.5 hours at 755 Centigrade, showing a temperature gradient of 10 Centigrade/minute). The structural characterization by powder X-ray diffraction (XDR) indicates that this elpasolite belongs to the Fm 3m (O h 5 ) space group and the optimized structural parameters are as follows: a 0 = 10.8342 Armstrong, V 1271.72 Armstrong 3 , Z=4, M=651.88, D x =3.406 y D exp=3.41 ± 0.01. The profile refinement, using the Rietveld method, allowed us to fit the experimental and the calculated intensities of a total of 32 lines. The above result indicates that the condition R exp 2+ + 3Cl -1 and the counter ions filling the octahedral holes, in full agreement with anti fluorite type crystal. According to the above description, these elpasolite adopt the form (M 1/3 □ 2/3 ) 4 X 2 , where M labels the central metal, X stand for the chlorine ions and □ represent the vacancies, which may accommodate a significant amount of defects without collapsing. This experimental study provides the necessary input to test theoretical models against experimental data. (Author)

  8. [Study on esterified modification of anthocyanins by FTIR].

    Science.gov (United States)

    Lu, Xiao-rui; Lu, Jin-li; Wu, Yan-wen; Ouyang, Jie; Sun, Su-qin

    2010-01-01

    Anthocyanins are relatively abundant in vegetables and fruits, which have potential positive health effects. The role of anthocyanins as food coloring agents becomes very important because they can provide attractive bright color of many food products. Nevertheless, the instability of natural anthocyanins was a big obstacle for its usage in food as colorants. The stability of the red radish anthocyanins is significantly improved by modified esterification of the colorant. Usually, the red radish anthocyanins was composed of several components of similar structures. The major methods for determining the structures of anthocyanin colorants involve chromatographic techniques such as TLC, HPLC and HPLC-MS, which are very useful in separation and identification of the components of anthocyanins However, compared to the spectroscopic method, the chromatographic methods are usually complicated and time-consuming during separation and analysis. In the present paper, the authors seek to establish a new, rapid and economic method for the analysis of structural change before and after esterified modification of anthcyanins in view of unique macro-fingerprint characteristics of infrared spectroscopy, which could reflect the whole change of complicated mixture system. The anthocyanins from red radish was esterification-modified by reacting with succinic anhydride, and the natural and modified anthocyanins were detected by FTIR The results showed that carbonyl of succinic anhydride was connected with the hydroxyl in glucosyl rings of anthocyanins to form new esterified anthocyanins, which are more stable than the natural one and present attractive bright color as usual.

  9. Instrumental characterization of clay by XRF, XRD and FTIR

    Indian Academy of Sciences (India)

    Instrumental characterizations of the clay were performed by different techniques such as XRF, XRD and FTIR. XRF shows the chemical compositions of the clay where Al-oxide and silica oxide are present in major quantity whereas XRD confirms the presence of these minerals in clay. FTIR studies show the presence of ...

  10. Quantification of Material State using Reflectance FTIR Spectroscopy (Preprint)

    Science.gov (United States)

    2017-12-08

    AFRL-RX-WP-JA-2017-0517 QUANTIFICATION OF MATERIAL STATE USING REFLECTANCE FTIR SPECTROSCOPY (PREPRINT) Amanda K. Criner and...Statement A. Approved for public release: distribution unlimited. (STINFO COPY) AIR FORCE RESEARCH LABORATORY MATERIALS AND MANUFACTURING...March 2014 – 8 November 2017 4. TITLE AND SUBTITLE QUANTIFICATION OF MATERIAL STATE USING REFLECTANCE FTIR SPECTROSCOPY (PREPRINT) 5a. CONTRACT

  11. Theoretical solid state physics

    CERN Document Server

    Haug, Albert

    2013-01-01

    Theoretical Solid State Physics, Volume 1 focuses on the study of solid state physics. The volume first takes a look at the basic concepts and structures of solid state physics, including potential energies of solids, concept and classification of solids, and crystal structure. The book then explains single-electron approximation wherein the methods for calculating energy bands; electron in the field of crystal atoms; laws of motion of the electrons in solids; and electron statistics are discussed. The text describes general forms of solutions and relationships, including collective electron i

  12. Theoretical study of the structure and reactivity of lanthanide and actinide based organometallic complexes; Etude theorique de la structure et de la reactivite de complexes organometalliques de lanthanides et d'actinides

    Energy Technology Data Exchange (ETDEWEB)

    Barros, N

    2007-06-15

    In this PhD thesis, lanthanide and actinide based organometallic complexes are studied using quantum chemistry methods. In a first part, the catalytic properties of organo-lanthanide compounds are evaluated by studying two types of reactions: the catalytic hydro-functionalization of olefins and the polymerisation of polar monomers. The reaction mechanisms are theoretically determined and validated, and the influence of possible secondary non productive reactions is envisaged. A second part focuses on uranium-based complexes. Firstly, the electronic structure of uranium metallocenes is analysed. An analogy with the uranyl compounds is proposed. In a second chapter, two isoelectronic complexes of uranium IV are studied. After validating the use of DFT methods for describing the electronic structure and the reactivity of these compounds, it is shown that their reactivity difference can be related to a different nature of chemical bonding in these complexes. (author)

  13. Application of microfluidic devices for time resolved FTIR spectroscopy

    International Nuclear Information System (INIS)

    Wagner, C.

    2012-01-01

    dichroic mirror. By continuously flowing sample through the measurement spot only fresh sample was excited for each measurement cycle, allowing the measurement of non- cyclic reactions. The rebinding kinetics of carbon monoxide to myoglobin, after photo dissociation of the carbonmonoxymyoglobin complex, was successfully investigated, showing bi-exponential reaction kinetics for the rebinding of the carbon monoxide and the relaxation of the induced changes in the protein's secondary structure. Measurements of the photo cycle of cytochrome c oxidase, however, failed due to physical limitations, such as the maximum possible concentration of cytochrome c oxidase and the path length of 10 μm needed to be able to measure the Amide I band of proteins in aqueous solution. As a third approach to time resolved measurements, fast scanning MOEMS spectrometers were evaluated. Poor signal to noise ratios, due to the early stage of the used prototypes, forced the use of intensive signal averaging, which nullified the advantage of faster scan rates, compared to standard FTIR spectrometers. (author) [de

  14. Distinction of broken cellular wall Ganoderma lucidum spores and G. lucidum spores using FTIR microspectroscopy

    Science.gov (United States)

    Chen, Xianliang; Liu, Xingcun; Sheng, Daping; Huang, Dake; Li, Weizu; Wang, Xin

    2012-11-01

    In this paper, FTIR microspectroscopy was used to identify broken cellular wall Ganoderma lucidum spores and G. lucidum spores. For IR spectra, broken cellular wall G. lucidum spores and G. lucidum spores were mainly different in the regions of 3000-2800, 1660-1600, 1400-1200 and 1100-1000 cm-1. For curve fitting, the results showed the differences in the protein secondary structures and the polysaccharide structures/content between broken cellular wall G. lucidum spores and G. lucidum spores. Moreover, the value of A1078/A1741 might be a potentially useful factor to distinguish broken cellular wall G. lucidum spores from G. lucidum spores. Additionally, FTIR microspectroscopy could identify broken cellular wall G. lucidum spores and G. lucidum spores accurately when it was combined with hierarchical cluster analysis. The result suggests FTIR microspectroscopy is very simple and efficient for distinction of broken cellular wall G. lucidum spores and G. lucidum spores. The result also indicates FTIR microspectroscopy may be useful for TCM identification.

  15. Ultra-compact MEMS FTIR spectrometer

    Science.gov (United States)

    Sabry, Yasser M.; Hassan, Khaled; Anwar, Momen; Alharon, Mohamed H.; Medhat, Mostafa; Adib, George A.; Dumont, Rich; Saadany, Bassam; Khalil, Diaa

    2017-05-01

    Portable and handheld spectrometers are being developed and commercialized in the late few years leveraging the rapidly-progressing technology and triggering new markets in the field of on-site spectroscopic analysis. Although handheld devices were commercialized for the near-infrared spectroscopy (NIRS), their size and cost stand as an obstacle against the deployment of the spectrometer as spectral sensing components needed for the smart phone industry and the IoT applications. In this work we report a chip-sized microelectromechanical system (MEMS)-based FTIR spectrometer. The core optical engine of the solution is built using a passive-alignment integration technique for a selfaligned MEMS chip; self-aligned microoptics and a single detector in a tiny package sized about 1 cm3. The MEMS chip is a monolithic, high-throughput scanning Michelson interferometer fabricated using deep reactive ion etching technology of silicon-on-insulator substrate. The micro-optical part is used for conditioning the input/output light to/from the MEMS and for further light direction to the detector. Thanks to the all-reflective design of the conditioning microoptics, the performance is free of chromatic aberration. Complemented by the excellent transmission properties of the silicon in the infrared region, the integrated solution allows very wide spectral range of operation. The reported sensor's spectral resolution is about 33 cm-1 and working in the range of 1270 nm to 2700 nm; upper limited by the extended InGaAs detector. The presented solution provides a low cost, low power, tiny size, wide wavelength range NIR spectral sensor that can be manufactured with extremely high volumes. All these features promise the compatibility of this technology with the forthcoming demand of smart portable and IoT devices.

  16. Application of spectroscopic methods for identification (FT-IR, Raman spectroscopy) and determination (UV, EPR) of quercetin-3-O-rutinoside. Experimental and DFT based approach.

    Science.gov (United States)

    Paczkowska, Magdalena; Lewandowska, Kornelia; Bednarski, Waldemar; Mizera, Mikołaj; Podborska, Agnieszka; Krause, Anna; Cielecka-Piontek, Judyta

    2015-04-05

    Vibrational (FT-IR, Raman) and electronic (UV, EPR) spectral measurements were performed for an analysis of rutin (quercetin-3-O-rutinoside) obtained from Rutaofficinalis. The identification of rutin was done with the use of FT-IR and Raman spectra. Those experimental spectra were determined with the support of theoretical calculations based on a DFT method with the B3LYP hybrid functional and 6-31G(d,p) basis set. The application of UV and EPR spectra was found to be a suitable analytical approach to the evaluation of changes in rutin exposed to certain physicochemical factors. Differences in absorbance observed in direct UV spectra were used to monitor changes in the concentration of rutin in degraded samples. Spectra of electron paramagnetic resonance allowed studying the process of free-radical quenching in rutin following its exposure to light. The molecular electrostatic potential (MEP) and frontier molecular orbitals (LUMO-HOMO) were also determined in order to predict structural changes and reactive sites in rutin. Copyright © 2015. Published by Elsevier B.V.

  17. Creating a Community of Practice to Prevent Suicide Through Multiple Channels: Describing the Theoretical Foundations and Structured Learning of PC CARES.

    Science.gov (United States)

    Wexler, Lisa; McEachern, Diane; DiFulvio, Gloria; Smith, Cristine; Graham, Louis F; Dombrowski, Kirk

    2016-01-01

    It is critical to develop practical, effective, ecological, and decolonizing approaches to indigenous suicide prevention and health promotion for the North American communities. The youth suicide rates in predominantly indigenous small, rural, and remote Northern communities are unacceptably high. This health disparity, however, is fairly recent, occurring over the last 50 to 100 years as communities experienced forced social, economic, and political change and intergenerational trauma. These conditions increase suicide risk and can reduce people's access to shared protective factors and processes. In this context, it is imperative that suicide prevention includes--at its heart--decolonization, while also utilizing the "best practices" from research to effectively address the issue from multiple levels. This article describes such an approach: Promoting Community Conversations About Research to End Suicide (PC CARES). PC CARES uses popular education strategies to build a "community of practice" among local and regional service providers, friends, and families that fosters personal and collective learning about suicide prevention in order to spur practical action on multiple levels to prevent suicide and promote health. This article will discuss the theoretical underpinnings of the community intervention and describe the form that PC CARES takes to structure ongoing dialogue, learning, solidarity, and multilevel mobilization for suicide prevention. © The Author(s) 2016.

  18. Theoretical investigations on the structural, spectroscopic, electronic and thermodynamic properties of (3-Oxo-3H-benzo[f]chromen-1yl methyl N,N-dimethylcarbamodithioate-1ex

    Directory of Open Access Journals (Sweden)

    Kara Mehmet

    2017-10-01

    Full Text Available Hartree-Fock and Density Functional Theory (B3LYP, B3PW91 calculations for the ground state of (3-Oxo-3Hbenzo[ f]chromen-1-yl methyl N,N-dimethylcarbamodithioate have been presented and the calculated structural parameters and energetic properties have been compared with the available X-ray diffraction data. The vibrational frequencies have been calculated using optimized geometry of the molecule. The conformational properties of the molecule have been determined by computing molecular energy properties, in which torsional angle varied from -180° to +180° in steps of 10°. Moreover, natural bond orbital analysis and atomic charge analysis have been performed. Besides, HOMO and LUMO energies have been calculated and their pictures have been presented. Finally, molecular electrostatic potential and thermodynamic properties have been calculated. It is seen that the obtained theoretical results agree well with the available experimental values. In all the calculations, except for optimization and vibrational calculations, B3LYP level of theory with 6-311++G(d,p basis set has been used.

  19. 4-N, N-bis(4-methoxylphenyl) aniline substituted anthraquinone: X-ray crystal structures, theoretical calculations and third-order nonlinear optical properties

    Science.gov (United States)

    Xu, Liang; Zhang, Dingfeng; Zhou, Yecheng; Zheng, Yusen; Cao, Liu; Jiang, Xiao-Fang; Lu, Fushen

    2017-08-01

    In this paper, mono- and di-4-N,N-bis(4-methoxylphenyl)aniline-substituted anthraquinone have been designed and synthesized through Suzuki reaction. For mono-4-N,N-bis(4-methoxylphenyl)aniline-substituted anthraquinone, polymorphous crystal structures have been obtained in different crystallization conditions. Electrochemical characterization combined with theoretical calculation suggests that the addition of a second triphenylamine unit causes a larger band gap with higher lying LUMO (Lowest Unoccupied Molecular Orbital) and HOMO (Highest Occupied Molecular Orbital). The linear optical property shows that the introduction of a second triphenylamine unit bring about a significant hyperchromic effect with the extinction coefficients increasing from 11199 M-1 cm-1 to 22136 M-1 cm-1. The third-order nonlinear optical properties indicate that the introduction of a second triphenylamine unit lead to a much larger nonlinear absorption coefficient and two-photon absorption cross section, with the relevant value increasing from 2.04 × 10-12 cm W-1 to 3.91 × 10-12 cm W-1, and from 148 GM to 286 GM, respectively.

  20. Theoretical studies on the electronic structures and spectral properties of a series of bis-cyclometalated iridium(III) complexes using density functional theory

    International Nuclear Information System (INIS)

    Han, Deming; Zhang, Gang; Cai, Hongxing; Zhang, Xihe; Zhao, Lihui

    2013-01-01

    We report a quantum-chemistry study of electronic structures and spectral properties of four Ir(III) complexes Ir[2-(2,4-di-X-phenyl)pyridine] 2 (picolinate), where X=–CH 3 (1), –H (2), –CN (3), –NO 2 (4). The absorption and emission spectra were calculated based on the optimized ground state and excited state geometries, respectively, by means of the time-dependent density functional theory (TDDFT). The effect from the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption, and phosphorescent properties has been investigated. The absorption and emission properties can be altered by the different electron-withdrawing and electron-donating groups. Besides, ionization potential (IP), electron affinities (EA) and reorganization energy (λ hole/electron ) were obtained to evaluate the charge transfer and balance properties between hole and electron. The calculated results show that the different substitute groups affect the charge transfer rate and balance. It can be anticipated that the complexes 3 and 4 have good charge transport rates and balance between the hole and electron. -- Highlights: ► Four Ir(III) complexes have been theoretically investigated. ► The different substituents affect the charge transfer rate and balance. ► We design two candidate materials for OLEDs