WorldWideScience

Sample records for chemical synthesis molecular

  1. Molecular design, synthesis and evaluation of chemical biology tools

    NARCIS (Netherlands)

    Hoogenboom, Jorin

    2017-01-01

    Chapter 1 provides a perspective of synthetic organic chemistry as a discipline involved in the design, synthesis and evaluation of complex molecules. The reader is introduced with a brief history of synthetic organic chemistry, all the while dealing with different aspects of

  2. Optimality principle for the coupled chemical reactions of ATP synthesis and its molecular interpretation

    Science.gov (United States)

    Nath, Sunil

    2018-05-01

    Metabolic energy obtained from the coupled chemical reactions of oxidative phosphorylation (OX PHOS) is harnessed in the form of ATP by cells. We experimentally measured thermodynamic forces and fluxes during ATP synthesis, and calculated the thermodynamic efficiency, η and the rate of free energy dissipation, Φ. We show that the OX PHOS system is tuned such that the coupled nonequilibrium processes operate at optimal η. This state does not coincide with the state of minimum Φ but is compatible with maximum Φ under the imposed constraints. Conditions that must hold for species concentration in order to satisfy the principle of optimal efficiency are derived analytically and a molecular explanation based on Nath's torsional mechanism of energy transduction and ATP synthesis is suggested. Differences of the proposed principle with Prigogine's principle are discussed.

  3. Synthesis, three-dimensional structure, conformation and correct chemical shift assignment determination of pharmaceutical molecules by NMR and molecular modeling

    Energy Technology Data Exchange (ETDEWEB)

    Azeredo, Sirlene O.F. de; Sales, Edijane M.; Figueroa-Villar, José D., E-mail: jdfv2009@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Grupo de Ressonância Magnética Nuclear e Química Medicinal

    2017-07-01

    This work includes the synthesis of phenanthrenequinone guanylhydrazone and phenanthro[9,10-e][1,2,4]triazin-3-amine to be tested as intercalate with DNA for treatment of cancer. The other synthesized product, 2-[(4-chlorophenylamino)methylene]malononitrile, was designed for future determination of its activity against leishmaniasis. A common problem about some articles on the literature is that some previously published compounds display error of their molecular structures. In this article it is shown the application of several procedures of nuclear magnetic resonance (NMR) to determine the complete molecular structure and the non questionable chemical shift assignment of the synthesized compounds, and also their analysis by molecular modeling to confirm the NMR results. To determine the capacity of pharmacological compounds to interact with biological targets is determined by docking. This work is to motivate the application of NMR and molecular modeling on organic synthesis, being a process that is very important for the study of the prepared compounds as interactions with biological targets by NMR. (author)

  4. Synthesis, three-dimensional structure, conformation and correct chemical shift assignment determination of pharmaceutical molecules by NMR and molecular modeling

    International Nuclear Information System (INIS)

    Azeredo, Sirlene O.F. de; Sales, Edijane M.; Figueroa-Villar, José D.

    2017-01-01

    This work includes the synthesis of phenanthrenequinone guanylhydrazone and phenanthro[9,10-e][1,2,4]triazin-3-amine to be tested as intercalate with DNA for treatment of cancer. The other synthesized product, 2-[(4-chlorophenylamino)methylene]malononitrile, was designed for future determination of its activity against leishmaniasis. A common problem about some articles on the literature is that some previously published compounds display error of their molecular structures. In this article it is shown the application of several procedures of nuclear magnetic resonance (NMR) to determine the complete molecular structure and the non questionable chemical shift assignment of the synthesized compounds, and also their analysis by molecular modeling to confirm the NMR results. To determine the capacity of pharmacological compounds to interact with biological targets is determined by docking. This work is to motivate the application of NMR and molecular modeling on organic synthesis, being a process that is very important for the study of the prepared compounds as interactions with biological targets by NMR. (author)

  5. Radiation chemical synthesis

    International Nuclear Information System (INIS)

    Zagoretz, P.A.; Poluetkov, V.A.; Shostenko, A.G.

    1986-01-01

    The authors consider processes in radiation chemical synthesis which are being developed in various scientific-research organizations. The important advantages of radiation chlorination, viz. the lower temperature compared with the thermal method and the absence of dehydrochlorination products are discussed. The authors examine the liquid-phase chlorination of trifluorochloroethyltrichloromethyl ether to obtain the pentachloro-contining ether, trifluorodichloroethyltrichloromethyl ether. The authors discuss radiation synthesis processes that have be used formulated kinetic equations on which models have been based. It is concluded that the possibilities of preparative (micro- and low-tonnage) radiation synthesis are promising

  6. Stereodivergent synthesis with a programmable molecular machine

    Science.gov (United States)

    Kassem, Salma; Lee, Alan T. L.; Leigh, David A.; Marcos, Vanesa; Palmer, Leoni I.; Pisano, Simone

    2017-09-01

    It has been convincingly argued that molecular machines that manipulate individual atoms, or highly reactive clusters of atoms, with Ångström precision are unlikely to be realized. However, biological molecular machines routinely position rather less reactive substrates in order to direct chemical reaction sequences, from sequence-specific synthesis by the ribosome to polyketide synthases, where tethered molecules are passed from active site to active site in multi-enzyme complexes. Artificial molecular machines have been developed for tasks that include sequence-specific oligomer synthesis and the switching of product chirality, a photo-responsive host molecule has been described that is able to mechanically twist a bound molecular guest, and molecular fragments have been selectively transported in either direction between sites on a molecular platform through a ratchet mechanism. Here we detail an artificial molecular machine that moves a substrate between different activating sites to achieve different product outcomes from chemical synthesis. This molecular robot can be programmed to stereoselectively produce, in a sequential one-pot operation, an excess of any one of four possible diastereoisomers from the addition of a thiol and an alkene to an α,β-unsaturated aldehyde in a tandem reaction process. The stereodivergent synthesis includes diastereoisomers that cannot be selectively synthesized through conventional iminium-enamine organocatalysis. We anticipate that future generations of programmable molecular machines may have significant roles in chemical synthesis and molecular manufacturing.

  7. Green chemistry for chemical synthesis

    OpenAIRE

    Li, Chao-Jun; Trost, Barry M.

    2008-01-01

    Green chemistry for chemical synthesis addresses our future challenges in working with chemical processes and products by inventing novel reactions that can maximize the desired products and minimize by-products, designing new synthetic schemes and apparati that can simplify operations in chemical productions, and seeking greener solvents that are inherently environmentally and ecologically benign.

  8. Green chemistry for chemical synthesis.

    Science.gov (United States)

    Li, Chao-Jun; Trost, Barry M

    2008-09-09

    Green chemistry for chemical synthesis addresses our future challenges in working with chemical processes and products by inventing novel reactions that can maximize the desired products and minimize by-products, designing new synthetic schemes and apparati that can simplify operations in chemical productions, and seeking greener solvents that are inherently environmentally and ecologically benign.

  9. Chemical synthesis on SU-8

    DEFF Research Database (Denmark)

    Qvortrup, Katrine; Taveras, Kennedy; Thastrup, Ole

    2011-01-01

    In this paper we describe a highly effective surface modification of SU-8 microparticles, the attachment of appropriate linkers for solid-supported synthesis, and the successful chemical modification of these particles via controlled multi-step organic synthesis leading to molecules attached...

  10. CLEAN CHEMICAL SYNTHESIS IN WATER

    Science.gov (United States)

    Newer green chemistry approach to accomplish chemical synthesis in water is summarized. Recent global developments pertaining to C-C bond forming reactions using metallic reagents and direct use of the renewable materials such as carbohydrates without derivatization are described...

  11. Deciphering a molecular mechanism of neonatal diabetes mellitus by the chemical synthesis of a protein diastereomer, [D-AlaB8]human proinsulin.

    Science.gov (United States)

    Avital-Shmilovici, Michal; Whittaker, Jonathan; Weiss, Michael A; Kent, Stephen B H

    2014-08-22

    Misfolding of proinsulin variants in the pancreatic β-cell, a monogenic cause of permanent neonatal-onset diabetes mellitus, provides a model for a disease of protein toxicity. A hot spot for such clinical mutations is found at position B8, conserved as glycine within the vertebrate insulin superfamily. We set out to investigate the molecular basis of the aberrant properties of a proinsulin clinical mutant in which residue Gly(B8) is replaced by Ser(B8). Modular total chemical synthesis was used to prepare the wild-type [Gly(B8)]proinsulin molecule and three analogs: [D-Ala(B8)]proinsulin, [L-Ala(B8)]proinsulin, and the clinical mutant [L-Ser(B8)]proinsulin. The protein diastereomer [D-Ala(B8)]proinsulin produced higher folding yields at all pH values compared with the wild-type proinsulin and the other two analogs, but showed only very weak binding to the insulin receptor. The clinical mutant [L-Ser(B8)]proinsulin impaired folding at pH 7.5 even in the presence of protein-disulfide isomerase. Surprisingly, although [L-Ser(B8)]proinsulin did not fold well under the physiological conditions investigated, once folded the [L-Ser(B8)]proinsulin protein molecule bound to the insulin receptor more effectively than wild-type proinsulin. Such paradoxical gain of function (not pertinent in vivo due to impaired secretion of the mutant insulin) presumably reflects induced fit in the native mechanism of hormone-receptor engagement. This work provides insight into the molecular mechanism of a clinical mutation in the insulin gene associated with diabetes mellitus. These results dramatically illustrate the power of total protein synthesis, as enabled by modern chemical ligation methods, for the investigation of protein folding and misfolding. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Apparatus for chemical synthesis

    Science.gov (United States)

    Kong, Peter C [Idaho Falls, ID; Herring, J Stephen [Idaho Falls, ID; Grandy, Jon D [Idaho Falls, ID

    2011-05-10

    A method and apparatus for forming a chemical hydride is described and which includes a pseudo-plasma-electrolysis reactor which is operable to receive a solution capable of forming a chemical hydride and which further includes a cathode and a movable anode, and wherein the anode is moved into and out of fluidic, ohmic electrical contact with the solution capable of forming a chemical hydride and which further, when energized produces an oxygen plasma which facilitates the formation of a chemical hydride in the solution.

  13. Wet chemical synthesis of soluble gold nanogaps

    DEFF Research Database (Denmark)

    Jain, Titoo; Tang, Qingxin; Bjørnholm, Thomas

    2014-01-01

    NRs) in aqueous solution. Through controlled end-to-end assembly of the AuNRs into dimers or chains, facilitated via target molecules, they can be used as electrical contacts. In this way, the preparation of AuNR-molecule-AuNR junctions by wet chemical methods may afford a large number of identical devices...... with little variation in the interface between molecule and electrode (AuNR). In this Account, we highlight recent progress in using chemically synthesized AuNRs as building blocks for molecular electronic applications. We outline the general synthesis and properties of AuNRs and describe the aqueous growth...... in the nanogaps lets us spectroscopically characterize the molecules via surface-enhanced Raman scattering. We discuss the incorporation of oligopeptides functionalized with acetylene units having uniquely identifiable vibrational modes. This acetylene moiety allows chemical reactions to be performed in the gaps...

  14. Radiation synthesis of carboxymethyl cellulose hydrogel imprinted with β-estradiol for molecular recognition of endocrine disruptive chemicals

    International Nuclear Information System (INIS)

    Dela Cruz, Rafael Miguel M.; Estorque, Kit Joshua J.

    2015-03-01

    This study demonstrates the possibility of synthesizing molecularly imprinted polymers (MIP) using carboxymethyl cellulose in low concentration and pH, and intiated by γ-irradiation. The capability of the synthesized MIPs to absorb specific molecules was demonstrated using an NIP which adsorbing capability was successfully done. The selectivity of molecules is beyond the scope of this study. Right amount of monomer and solvents affects the capability of the imprinted polymer to be formed. It was also found out that it is important to acidify the CMC mixture to enable the cross-linking of CMC chains without using a cross-linker. It was confirmed that β-estradiol is soluble in acentonitrile by subjecting the mixture to UV-Vis spectrophotometry. The Incorporation of β-estradiol to CMC after γ-irradiation was also confirmed using FTIR-ATR. (author)

  15. Molecular structure, chemical synthesis, and antibacterial activity of ABP-dHC-cecropin A from drury (Hyphantria cunea).

    Science.gov (United States)

    Zhang, Jiaxin; Movahedi, Ali; Wang, Xiaoli; Wu, Xiaolong; Yin, Tongming; Zhuge, Qiang

    2015-06-01

    The increasing resistance of bacteria and fungi to currently available antibiotics is a major concern worldwide, leading to enormous efforts to develop new antibiotics with new modes of actions. In this paper, cDNA encoding cecropin A was amplified from drury (Hyphantria cunea) (dHC) pupa fatbody total RNA using RT-PCR. The full-length dHC-cecropin A cDNA encoded a protein of 63 amino acids with a predicted 26-amino acid signal peptide and a 37-amino acid functional domain. We synthesized the antibacterial peptide (ABP) from the 37-amino acid functional domain (ABP-dHC-cecropin A), and amidated it via the C-terminus. Time-of-flight mass spectrometry showed its molecular weight to be 4058.94. The ABP-dHC-cecropin A was assessed in terms of its protein structure using bioinformatics and CD spectroscopy. The protein's secondary structure was predicted to be α-helical. In an antibacterial activity analysis, the ABP-dHC-cecropin A exhibited strong antibacterial activity against E. coli K12D31 and Agrobacterium EHA105. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Molecular Regulation of Histamine Synthesis

    Directory of Open Access Journals (Sweden)

    Hua Huang

    2018-06-01

    Full Text Available Histamine is a critical mediator of IgE/mast cell-mediated anaphylaxis, a neurotransmitter and a regulator of gastric acid secretion. Histamine is a monoamine synthesized from the amino acid histidine through a reaction catalyzed by the enzyme histidine decarboxylase (HDC, which removes carboxyl group from histidine. Despite the importance of histamine, transcriptional regulation of HDC gene expression in mammals is still poorly understood. In this review, we focus on discussing advances in the understanding of molecular regulation of mammalian histamine synthesis.

  17. Chemical Synthesis of Circular Proteins*

    Science.gov (United States)

    Tam, James P.; Wong, Clarence T. T.

    2012-01-01

    Circular proteins, once thought to be rare, are now commonly found in plants. Their chemical synthesis, once thought to be difficult, is now readily achievable. The enabling methodology is largely due to the advances in entropic chemical ligation to overcome the entropy barrier in coupling the N- and C-terminal ends of large peptide segments for either intermolecular ligation or intramolecular ligation in end-to-end cyclization. Key elements of an entropic chemical ligation consist of a chemoselective capture step merging the N and C termini as a covalently linked O/S-ester intermediate to permit the subsequent step of an intramolecular O/S-N acyl shift to form an amide. Many ligation methods exploit the supernucleophilicity of a thiol side chain at the N terminus for the capture reaction, which makes cysteine-rich peptides ideal candidates for the entropy-driven macrocyclization. Advances in desulfurization and modification of the thiol-containing amino acids at the ligation sites to other amino acids add extra dimensions to the entropy-driven ligation methods. This minireview describes recent advances of entropy-driven ligation to prepare circular proteins with or without a cysteinyl side chain. PMID:22700959

  18. Standardized chemical synthesis of Pseudomonas aeruginosa pyocyanin

    Directory of Open Access Journals (Sweden)

    Rajkumar Cheluvappa

    2014-01-01

    As we have extracted pyocyanin both from P. aeruginosa cultures, and via chemical synthesis; we know the procedural and product-quality differences. We endorse the relative ease, safety, and convenience of using the chemical synthesis described here. Crucially, our “naturally endotoxin-free” pyocyanin can be extracted easily without using infectious bacteria.

  19. Tools for chemical synthesis in microsystems

    OpenAIRE

    Jensen, Klavs F.; Newman, Stephen G.; Reizman, Brandon Jacob

    2014-01-01

    Chemical synthesis in microsystems has evolved from simple proof-of-principle examples to become a general technique in academia and industry. Numerous such “flow chemistry” applications are now found in pharmaceutical and fine chemical synthesis. Much of the development has been based on systems employing macroscopic flow components and tubes, rather than the integrated chip technology envisioned by the lab-on-a-chip community. We review the major developments in systems for flow chemistry a...

  20. Method for innovative synthesis-design of chemical process flowsheets

    DEFF Research Database (Denmark)

    Kumar Tula, Anjan; Gani, Rafiqul

    Chemical process synthesis-design involve the identification of the processing route to reach a desired product from a specified set of raw materials, design of the operations involved in the processing route, the calculations of utility requirements, the calculations of waste and emission...... to the surrounding and many more. Different methods (knowledge-based [1], mathematical programming [2], hybrid, etc.) have been proposed and are also currently employed to solve these synthesis-design problems. D’ Anterroches [3] proposed a group contribution based approach to solve the synthesis-design problem...... of chemical processes, where, chemical process flowsheets could be synthesized in the same way as atoms or groups of atoms are synthesized to form molecules in computer aided molecular design (CAMD) techniques [4]. That, from a library of building blocks (functional process-groups) and a set of rules to join...

  1. Protein chemical synthesis by α-ketoacid-hydroxylamine ligation.

    Science.gov (United States)

    Harmand, Thibault J; Murar, Claudia E; Bode, Jeffrey W

    2016-06-01

    Total chemical synthesis of proteins allows researchers to custom design proteins without the complex molecular biology that is required to insert non-natural amino acids or the biocontamination that arises from methods relying on overexpression in cells. We describe a detailed procedure for the chemical synthesis of proteins with the α-ketoacid-hydroxylamine (KAHA ligation), using (S)-5-oxaproline (Opr) as a key building block. This protocol comprises two main parts: (i) the synthesis of peptide fragments by standard fluorenylmethoxycarbonyl (Fmoc) chemistry and (ii) the KAHA ligation between fragments containing Opr and a C-terminal peptide α-ketoacid. This procedure provides an alternative to native chemical ligation (NCL) that could be valuable for the synthesis of proteins, particularly targets that do not contain cysteine residues. The ligation conditions-acidic DMSO/H2O or N-methyl-2-pyrrolidinone (NMP)/H2O-are ideally suited for solubilizing peptide segments, including many hydrophobic examples. The utility and efficiency of the protocol is demonstrated by the total chemical synthesis of the mature betatrophin (also called ANGPTL8), a 177-residue protein that contains no cysteine residues. With this protocol, the total synthesis of the betatrophin protein has been achieved in around 35 working days on a multimilligram scale.

  2. ANALYTICAL SYNTHESIS OF CHEMICAL REACTOR CONTROL SYSTEM

    Directory of Open Access Journals (Sweden)

    Alexander Labutin

    2017-02-01

    Full Text Available The problem of the analytical synthesis of the synergetic control system of chemical reactor for the realization of a complex series-parallel exothermal reaction has been solved. The synthesis of control principles is performed using the analytical design method of aggregated regulators. Synthesized nonlinear control system solves the problem of stabilization of the concentration of target component at the exit of reactor and also enables one to automatically transfer to new production using the equipment.

  3. Methanol synthesis beyond chemical equilibrium

    NARCIS (Netherlands)

    van Bennekom, J. G.; Venderbosch, R. H.; Winkelman, J. G. M.; Wilbers, E.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2013-01-01

    In commercial methanol production from syngas, the conversion is thermodynamically limited to 0.3-0.7 leading to large recycles of non-converted syngas. This problem can be overcome to a significant extent by in situ condensation of methanol during its synthesis which is possible nowadays due to the

  4. MICROWAVE TECHNOLOGY CHEMICAL SYNTHESIS APPLICATIONS

    Science.gov (United States)

    Microwave-accelerated chemical syntheses in various solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although th...

  5. Design and synthesis of a biotinylated chemical probe for detecting the molecular targets of an inhibitor of the production of the Pseudomonas aeruginosa virulence factor pyocyanin.

    Science.gov (United States)

    Baker, Ysobel R; Galloway, Warren R J D; Hodgkinson, James T; Spring, David R

    2013-09-25

    Pseudomonas aeruginosa is a human pathogen associated with a variety of life-threatening nosocomial infections. This organism produces a range of virulence factors which actively cause damage to host tissues. One such virulence factor is pyocyanin, known to play a crucial role in the pathogenesis of P. aeruginosa infections. Previous studies had identified a novel compound capable of strongly inhibiting the production of pyocyanin. It was postulated that this inhibition results from modulation of an intercellular communication system termed quorum sensing, via direct binding of the compound with the LasR protein receptor. This raised the possibility that the compound could be an antagonist of quorum sensing in P. aeruginosa, which could have important implications as this intercellular signaling mechanism is known to regulate many additional facets of P. aeruginosa pathogenicity. However, there was no direct evidence for the binding of the active compound to LasR (or any other targets). Herein we describe the design and synthesis of a biotin-tagged version of the active compound. This could potentially be used as an affinity-based chemical probe to ascertain, in a direct fashion, the active compound's macromolecular biological targets, and thus better delineate the mechanism by which it reduces the level of pyocyanin production.

  6. SYNTHESIS, PHYSICO-CHEMICAL AND ANTIMICROBIAL ...

    African Journals Online (AJOL)

    userpc

    -125. Byeong G. Chae D., Hae N., Hyung K. C. and. Yong K. C. (1996); Synthesis and characterization of schiff base derived 2- hydroxy napthaldehyde and aliphatic diammines. Bulletin Korean Chemical. Society 17(8): 687-693. Hassan S. W. ...

  7. Synthesis, characterization, antimicrobial activity and molecular ...

    African Journals Online (AJOL)

    Synthesis, characterization, antimicrobial activity and molecular docking studies of combined pyrazol-barbituric acid pharmacophores. Assem Barakat, Bandar M. Al-Qahtani, Abdullah M. Al-Majid, M. Ali Mohammed Rafi Shaik, Mohamed H.M. Al-Agamy, Abdul Wadood ...

  8. The Chemical Synthesis of Discodermolide

    Science.gov (United States)

    Paterson, I.; Florence, G. J.

    The marine sponge-derived polyketide discodermolide is a potent antimitotic agent that represents a promising natural product lead structure in the treatment of cancer. Discodermolide shares the same microtubule-stabilising mechanism of action as Taxol®, inhibits the growth of solid tumours in animal models and shows synergy with Taxol. The pronounced cytotoxicity of discodermolide, which is maintained against cancer cell lines that display resistance to Taxol and other drugs, combined with its scarce availability from its natural source, has fuelled significant academic and industrial interest in devising a practical total synthesis as a means of ensuring a sustainable supply for drug development. This chapter surveys the various total syntheses of discodermolide that have been completed over the period 1993-2007, focusing on the strategies employed for introduction of the multiple stereocentres and achieving control over the alkene geometry, along with the various methods used for realising the pivotal fragment couplings to assemble progressively the full carbon skeleton. This dedicated synthetic effort has triumphed in removing the supply problem for discodermolide, providing sufficient material for extensive biological studies and enabling its early stage clinical development, as well as facilitating SAR studies for lead optimisation.

  9. Speciality chemicals from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.J.; Knifton, J.F. (Shell Development Company, Houston, TX (USA))

    1992-04-01

    Texaco has undertaken research to investigate the use of carbon monoxide and hydrogen as building blocks for the manufacture of amidocarbonylation products. The amidocarbonylation reaction offers a convenient method to construct two functionalities - amido and carboxylate - simultaneously. Texaco has extended this chemistry to make a variety of speciality chemicals by tailoring cobalt catalysts. Products which have been made including: surface active agents such as the C{sub 14} - C{sub 16} alkyl amidoacids; surfactants; intermediates for sweeteners like aspartame; food additives like glutamic acid; and chelating agents such as polyamidoacids. 20 refs., 10 figs., 1 tab.

  10. Alternative Fuels and Chemicals from Synthesis Gas

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1998-12-02

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  11. Alternative fuels and chemicals from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1998-08-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  12. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1999-01-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  13. Alternative Fuels and Chemicals From Synthesis Gas

    Energy Technology Data Exchange (ETDEWEB)

    none

    1998-07-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  14. molecular dynamics simulations and quantum chemical calculations

    African Journals Online (AJOL)

    ABSTRACT. The molecular dynamic (MD) simulation and quantum chemical calculations for the adsorption of [2-(2-Henicos-10- .... electronic properties of molecule clusters, surfaces and ... The local reactivity was analyzed by determining the.

  15. Synthesis, spectroscopic analyses (FT-IR and NMR), vibrational study, chemical reactivity and molecular docking study and anti-tubercular activity of condensed oxadiazole and pyrazine derivatives

    Science.gov (United States)

    El-Azab, Adel S.; Mary, Y. Sheena; Abdel-Aziz, Alaa A. M.; Miniyar, Pankaj B.; Armaković, Stevan; Armaković, Sanja J.

    2018-03-01

    The Fourier transform infrared spectra of the compounds 2-(5-phenyl-1,3,4-oxadiazol-2-yl)pyrazine (PHOXPY), 2-(5-styryl-1,3,4-oxadiazol-2-yl)pyrazine (STOXPY) and 2-(5-(furan-2-yl)-1,3,4-oxadiazol-2-yl)pyrazine (FUOXPY) have been recorded and the wavenumbers are computed at the density functional theory level. The assignments of all the fundamental bands of each molecule are made using potential energy distribution. The computed values of dipole moment, polarizability and hyperpolarizability values indicate that the title molecules exhibit NLO properties. The HOMO and LUMO energies demonstrate the chemical stability of the molecules and NBO analysis is made to study the stability of molecules arising from hyper conjugative interactions and charge delocalization. Detailed computational analysis and spectroscopic characterization has been performed for three newly synthesized oxadiazole derivatives. Obtained computational and experimental results have been mutually compared in order to understand the influence of structural parts specific for each derivative. From the MIC determination, MTb H37Rv was found to be sensitive to compounds, PHOXPY, STOXPY and FUOXPY. The results obtained from anti-TB activity are more promising as the compounds were found to be more potent than reference standards, streptomycin and pyrazinamide. Efforts were made in order to predict both global and local reactive properties of the title oxadiazole derivatives, including their sensitivity towards autoxidation mechanism and influence of water. The results obtained from anti-TB activity are more promising for the title compounds. Interaction with representative protein Pterindeaminase inhibitor asricin A was also investigated using the molecular docking procedure. The docked ligands form stable complexes with the receptor ricin A and the docking results suggest that these compounds can be developed as new anti-cancer drugs.

  16. Atomic and Molecular Manipulation of Chemical Interactions

    National Research Council Canada - National Science Library

    Ho, Wilson

    2007-01-01

    .... In effect, the goal is to carry out chemical changes by manipulating individual atoms and molecules to induce different bonding geometry and to create new interactions with their environment. These studies provide the scientific basis for the advancement of technology in catalysis, molecular electronics, optics, chemical and biological sensing, and magnetic storage.

  17. Multimedia environmental chemical partitioning from molecular information

    International Nuclear Information System (INIS)

    Martinez, Izacar; Grifoll, Jordi; Giralt, Francesc; Rallo, Robert

    2010-01-01

    The prospect of assessing the environmental distribution of chemicals directly from their molecular information was analyzed. Multimedia chemical partitioning of 455 chemicals, expressed in dimensionless compartmental mass ratios, was predicted by SimpleBox 3, a Level III Fugacity model, together with the propagation of reported uncertainty for key physicochemical and transport properties, and degradation rates. Chemicals, some registered in priority lists, were selected according to the availability of experimental property data to minimize the influence of predicted information in model development. Chemicals were emitted in air or water in a fixed geographical scenario representing the Netherlands and characterized by five compartments (air, water, sediments, soil and vegetation). Quantitative structure-fate relationship (QSFR) models to predict mass ratios in different compartments were developed with support vector regression algorithms. A set of molecular descriptors, including the molecular weight and 38 counts of molecular constituents were adopted to characterize the chemical space. Out of the 455 chemicals, 375 were used for training and testing the QSFR models, while 80 were excluded from model development and were used as an external validation set. Training and test chemicals were selected and the domain of applicability (DOA) of the QSFRs established by means of self-organizing maps according to structural similarity. Best results were obtained with QSFR models developed for chemicals belonging to either the class [C] and [C; O], or the class with at least one heteroatom different than oxygen in the structure. These two class-specific models, with respectively 146 and 229 chemicals, showed a predictive squared coefficient of q 2 ≥ 0.90 both for air and water, which respectively dropped to q 2 ∼ 0.70 and 0.40 for outlying chemicals. Prediction errors were of the same order of magnitude as the deviations associated to the uncertainty of the

  18. Chemical Reduction Synthesis of Iron Aluminum Powders

    Science.gov (United States)

    Zurita-Méndez, N. N.; la Torre, G. Carbajal-De; Ballesteros-Almanza, L.; Villagómez-Galindo, M.; Sánchez-Castillo, A.; Espinosa-Medina, M. A.

    In this study, a chemical reduction synthesis method of iron aluminum (FeAl) nano-dimensional intermetallic powders is described. The process has two stages: a salt reduction and solvent evaporation by a heat treatment at 1100°C. The precursors of the synthesis are ferric chloride, aluminum foil chips, a mix of Toluene/THF in a 75/25 volume relationship, and concentrated hydrochloric acid as initiator of the reaction. The reaction time was 20 days, the product obtained was dried at 60 °C for 2 h and calcined at 400, 800, and 1100 °C for 4 h each. To characterize and confirm the obtained synthesis products, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques were used. The results of morphology and chemical characterization of nano-dimensional powders obtained showed a formation of agglomerated particles of a size range of approximately 150 nm to 1.0 μm. Composition of powders was identified as corundum (Al2O3), iron aluminide (FeAl3), and iron-aluminum oxides (Fe0. 53Al0. 47)2O3 phases. The oxide phases formation were associated with the reaction of atmospheric concentration-free oxygen during synthesis and sintering steps, reducing the concentration of the iron aluminum phase.

  19. Environmentally benign chemical synthesis and processing

    International Nuclear Information System (INIS)

    Hancock, K.G.

    1992-01-01

    A new era of university-industry-government partnership is required to address the intertwined problems of industrial economic competitiveness and environmental quality. Chemicals that go up the stacks and down the drains are simultaneously a serious detriment to the environment, a waste of natural resources, and a threat to industrial profitability. Recently, the NSF Divisions of Chemistry and chemical and Thermal Systems have joined with the Council for Chemical research in a new grant program to reduce pollution at the source by underwriting research aimed at environmentally benign chemical synthesis and processing. Part of a broader NSF initiative on environmental science research, this new program serves as a model for university-industry-government joint action and technology transfer. Other features of this program and related activities will be described in this paper

  20. Opportunities for Merging Chemical and Biological Synthesis

    Science.gov (United States)

    Wallace, Stephen; Balskus, Emily P.

    2014-01-01

    Organic chemists and metabolic engineers use largely orthogonal technologies to access small molecules like pharmaceuticals and commodity chemicals. As the use of biological catalysts and engineered organisms for chemical production grows, it is becoming increasingly evident that future efforts for chemical manufacture will benefit from the integration and unified expansion of these two fields. This review will discuss approaches that combine chemical and biological synthesis for small molecule production. We highlight recent advances in combining enzymatic and non-enzymatic catalysis in vitro, discuss the application of design principles from organic chemistry for engineering non-biological reactivity into enzymes, and describe the development of biocompatible chemistry that can be interfaced with microbial metabolism. PMID:24747284

  1. Mapping student thinking in chemical synthesis

    Science.gov (United States)

    Weinrich, Melissa

    In order to support the development of learning progressions about central ideas and practices in different disciplines, we need detailed analyses of the implicit assumptions and reasoning strategies that guide students' thinking at different educational levels. In the particular case of chemistry, understanding how new chemical substances are produced (chemical synthesis) is of critical importance. Thus, we have used a qualitative research approach based on individual interviews with first semester general chemistry students (n = 16), second semester organic chemistry students (n = 15), advanced undergraduates (n = 9), first year graduate students (n = 15), and PhD candidates (n = 16) to better characterize diverse students' underlying cognitive elements (conceptual modes and modes of reasoning) when thinking about chemical synthesis. Our results reveal a great variability in the cognitive resources and strategies used by students with different levels of training in the discipline to make decisions, particularly at intermediate levels of expertise. The specific nature of the task had a strong influence on the conceptual sophistication and mode of reasoning that students exhibited. Nevertheless, our data analysis has allowed us to identify common modes of reasoning and assumptions that seem to guide students' thinking at different educational levels. Our results should facilitate the development of learning progressions that help improve chemistry instruction, curriculum, and assessment.

  2. Molecular activation analysis for chemical speciation studies

    International Nuclear Information System (INIS)

    Chai-Chifang

    1998-01-01

    The term of Molecular Activation Analysis (MAA) refers to an activation analysis method that is able to provide information about the chemical species of elements in system of interests, though its definition has remained to be assigned. Its development is strongly stimulated by the urgent need to know the chemical species of elements, because the total concentrations are often without any meaning when assessing health or environmental risks of trace elements.In practice, the MAA is a combination of conventional instrumental or radiochemical activation analysis and physical, chemical or biochemical separation techniques. The MAA is able to play a particular role in speciation studies. However, the critical point in the MAA is that it is not permitted to change the primitive chemical species of elements in systems, or the change has to be under control; in the meantime it is not allowed to form the 'new artifact' originally not present in systems. Some practical examples of MAA for chemical species research performed recently in our laboratory will be presented as follows: Chemical species of platinum group elements in sediment; Chemical species of iodine in marine algae; Chemical species of mercury in human tissues; Chemical species of selenium in corn; Chemical species of rare earth elements in natural plant, etc. The merits and limitations of MAA will be described as well. (author)

  3. Molecularly Imprinted Polymer Synthesis Using RAFT Polymerisation

    International Nuclear Information System (INIS)

    Cormack, P.A.G.; Faizatul Shimal Mehamod; Faizatul Shimal Mehamod

    2013-01-01

    In this paper, the synthesis and characterisation of caffeine-imprinted polymers are described. The polymers were prepared in monolithic form via both reversible addition-fragmentation chain-transfer (RAFT) polymerisation and conventional free radical polymerisation, using methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and crosslinking agent, respectively. The potential benefits in applying RAFT polymerisation techniques towards the synthesis of molecularly imprinted polymers (MIPs) are explored and elucidated. The pore structures of the polymers produced were characterised by nitrogen sorption porosimetry and the molecular recognition properties of representative products were evaluated in high-performance liquid chromatography (HPLC) mode. Molecular imprinting effects were confirmed by analysing the relative retentions of analytes on imprinted and non-imprinted HPLC stationary phases. It was found that a caffeine-imprinted polymer synthesised by RAFT polymerisation was superior to a polymer prepared using a conventional synthetic approach; the imprinting factor and column efficiency were found to be higher for the former material. (author)

  4. Molecular activation analysis for chemical species studies

    International Nuclear Information System (INIS)

    Chai Zhifang; Mao Xueying; Wang Yuqi; Sun Jingxin; Qian Qingfang; Hou Xiaolin; Zhang Peiqun; Chen Chunying; Feng Weiyu; Ding Wenjun; Li Xiaolin; Li Chunsheng; Dai Xiongxin

    2001-01-01

    The Molecular Activation Analysis (MAA) mainly refers to an activation analysis method that is able to provide information about the chemical species of elements in systems of interest, though its exact definition has remained to be assigned. Its development is strongly stimulated by the urgent need to know the chemical species of elements, because the bulk contents or concentrations are often insignificant for judging biological, environmental or geochemical effects of elements. In this paper, the features, methodology and limitation of MAA were outlined. Further, the up-to-date MAA progress made in our laboratory was introduced as well. (author)

  5. Molecular dynamics simulation of a chemical reaction

    International Nuclear Information System (INIS)

    Gorecki, J.; Gryko, J.

    1988-06-01

    Molecular dynamics is used to study the chemical reaction A+A→B+B. It is shown that the reaction rate constant follows the Arrhenius law both for Lennard-Jones and hard sphere interaction potentials between substrate particles. A. For the denser systems the reaction rate is proportional to the value of the radial distribution function at the contact point of two hard spheres. 10 refs, 4 figs

  6. Molecular orbital calculations using chemical graph theory

    CERN Document Server

    Dias, Jerry Ray

    1993-01-01

    Professor John D. Roberts published a highly readable book on Molecular Orbital Calculations directed toward chemists in 1962. That timely book is the model for this book. The audience this book is directed toward are senior undergraduate and beginning graduate students as well as practicing bench chemists who have a desire to develop conceptual tools for understanding chemical phenomena. Although, ab initio and more advanced semi-empirical MO methods are regarded as being more reliable than HMO in an absolute sense, there is good evidence that HMO provides reliable relative answers particularly when comparing related molecular species. Thus, HMO can be used to rationalize electronic structure in 1t-systems, aromaticity, and the shape use HMO to gain insight of simple molecular orbitals. Experimentalists still into subtle electronic interactions for interpretation of UV and photoelectron spectra. Herein, it will be shown that one can use graph theory to streamline their HMO computational efforts and to arrive...

  7. Molecular computing: paths to chemical Turing machines.

    Science.gov (United States)

    Varghese, Shaji; Elemans, Johannes A A W; Rowan, Alan E; Nolte, Roeland J M

    2015-11-13

    To comply with the rapidly increasing demand of information storage and processing, new strategies for computing are needed. The idea of molecular computing, where basic computations occur through molecular, supramolecular, or biomolecular approaches, rather than electronically, has long captivated researchers. The prospects of using molecules and (bio)macromolecules for computing is not without precedent. Nature is replete with examples where the handling and storing of data occurs with high efficiencies, low energy costs, and high-density information encoding. The design and assembly of computers that function according to the universal approaches of computing, such as those in a Turing machine, might be realized in a chemical way in the future; this is both fascinating and extremely challenging. In this perspective, we highlight molecular and (bio)macromolecular systems that have been designed and synthesized so far with the objective of using them for computing purposes. We also present a blueprint of a molecular Turing machine, which is based on a catalytic device that glides along a polymer tape and, while moving, prints binary information on this tape in the form of oxygen atoms.

  8. Oxygenated base chemicals from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Roeper, M.

    1984-11-01

    Methyl formate, a syngas based intermediate, is already today produced on large scale by base catalyzed methanol carbonylation. An alternative synthesis, based on methanol dehydrogenation, seems to be ready for commercialization, whereas other routes including direct carbon monoxide hydrogenation, formaldehyde disproportionation or methanol oxydehydrogenation are less advanced. Besides being used as a solvent or an insect control agent, methyl formate serves as a feedstock for e.g. formic acid, formamide, N,N-dimethylformamide, and N-formyl morpholine. Newer formic acid processes are based on direct hydrolysis of methyl formate, and appear to replace the traditional indirect formamide based route. Future use of methyl formate could include the production of pure carbon monoxide, methanol, dimethyl carbonate, diphosgene, ethylene glycol via methyl glycolate, acetic acid, and methyl propionate. All these processes either avoid the use of high purity carbon monoxide or proceed under milder conditions than conventional routes. They could gain interest, if syngas and methanol become available at a large scale as competitive feedstocks for the chemical industry.

  9. Computational Chemical Synthesis Analysis and Pathway Design

    Directory of Open Access Journals (Sweden)

    Fan Feng

    2018-06-01

    Full Text Available With the idea of retrosynthetic analysis, which was raised in the 1960s, chemical synthesis analysis and pathway design have been transformed from a complex problem to a regular process of structural simplification. This review aims to summarize the developments of computer-assisted synthetic analysis and design in recent years, and how machine-learning algorithms contributed to them. LHASA system started the pioneering work of designing semi-empirical reaction modes in computers, with its following rule-based and network-searching work not only expanding the databases, but also building new approaches to indicating reaction rules. Programs like ARChem Route Designer replaced hand-coded reaction modes with automatically-extracted rules, and programs like Chematica changed traditional designing into network searching. Afterward, with the help of machine learning, two-step models which combine reaction rules and statistical methods became the main stream. Recently, fully data-driven learning methods using deep neural networks which even do not require any prior knowledge, were applied into this field. Up to now, however, these methods still cannot replace experienced human organic chemists due to their relatively low accuracies. Future new algorithms with the aid of powerful computational hardware will make this topic promising and with good prospects.

  10. Chemical reactor development : from laboratory synthesis to industrial production

    NARCIS (Netherlands)

    Thoenes, D.

    1998-01-01

    Chemical Reactor Development is written primarily for chemists and chemical engineers who are concerned with the development of a chemical synthesis from the laboratory bench scale, where the first successful experiments are performed, to the design desk, where the first commercial reactor is

  11. Recent Progress in Chemical and Chemoenzymatic Synthesis of Carbohydrates

    Science.gov (United States)

    Muthana, Saddam; Cao, Hongzhi; Chen, Xi

    2011-01-01

    Summary The important roles that carbohydrates play in biological processes and their potential application in diagnosis, therapeutics, and vaccine development have made them attractive synthetic targets. Despite ongoing challenges, tremendous progresses have been made in recent years for the synthesis of carbohydrates. The chemical glycosylation methods have become more sophisticated and the synthesis of oligosaccharides has become more predictable. Simplified one-pot glycosylation strategy and automated synthesis are increasingly used to obtain biologically important glycans. On the other hand, chemoenzymatic synthesis continues to be a powerful alternative for obtaining complex carbohydrates. This review highlights recent progress in chemical and chemoenzymatic synthesis of carbohydrates with a particular focus on the methods developed for the synthesis of oligosaccharides, polysaccharides, glycolipids, and glycosylated natural products. PMID:19833544

  12. Chemical applications of molecular quantum theory

    International Nuclear Information System (INIS)

    Ungemach, S.R.

    1977-09-01

    Molecular systems of chemical interest are investigated with the aid of molecular quantum theory. The self-consistent field (SCF) method is used to predict the molecular structures of ClF 2 , ClF 4 and Cl 3 radicals, and the ions ClF 2 + , ClF 2 - , ClF 4 + and ClF 4 - . The ClF 2 and Cl 3 radicals are predicted to be bent with bond angles of 145.2 0 and 158.6 0 , respectively, while the ions ClF 2 + and ClF 2 - are predicted to be bent with a bond angle of 97.4 0 and linear, respectively. The geometry predictions for the ClF 4 radical and the ClF 4 + ion are found to be notably basis set dependent. The ClF 4 - ion is predicted to be square-planar. Multi-configuration self-consistent field (MCSCF) calculations have yielded the dipole moment function for the 1 sigma + state of HI, which qualitatively confirms the experimental finding that the dipole derivative at R/sub e/ is negative. The 2 sigma + F + H 2 potential energy surface is studied extensively with the configuration interaction (CI) method. The most complete calculations yield an activation energy of 2.74 kcal/mole and an exothermicity of 30.0 kcal/mole. The production of a potential energy surface of ''chemical accuracy'' for this system is found to be more difficult than previously believed. The simplest hydrophobic model, the water-methane system, is studied with the SCF method in order to determine the nature and magnitude of the interaction. The most favorable geometric arrangement corresponds to an attraction of 0.5 kcal/mole

  13. Molecular clips based on propanediurea : synthesis and physical properties

    NARCIS (Netherlands)

    Jansen, Robertus Johannes

    2002-01-01

    This thesis describes the synthesis and physical properties of a series of molecular clips derived from the concave molecule propanediurea. These molecular clips are cavity-containing receptors that can bind a variety of aromatic guests. This binding is a result of hydrogen bonding and pi-pi

  14. Hydroxyapatite, a biomaterial: Its chemical synthesis ...

    Indian Academy of Sciences (India)

    The surface area and particle size of HAP powder prepared by chemical precipitation route, were also ... chemical precipitation method (Jarcho 1978). The powders .... den snail shell, Helix aspersa, was done by taking tris-HCl buffer solution.

  15. FACILITATED CHEMICAL SYNTHESIS UNDER ALTERNATE REACTION CONDITIONS

    Science.gov (United States)

    The chemical research in the late 1990's witnessed a paradigm shift towards "environmentally-friendly chemistry" more popularly known as "green chemistry" due to the increasing environmental concerns and legislative requirements to curb the release of chemical waste into the atmo...

  16. A Network of AOPs for reduced thyroid hormone synthesis derived from inhibition of Thyroperoxidase - A common Molecular Initiating Event Leading to Species-Specific Indices of Adversity.

    Science.gov (United States)

    This collection of 3 AOPs describe varying outcomes of adversity dependent upon species in response to inhibition of thyroperoxidase (TPO) during development. Chemical inhibition of TPO, the molecular-initiating event (MIE), results in decreased thyroid hormone (TH) synthesis, a...

  17. Synthesis and Characterisation of Aluminophosphate Molecular Sieves

    Energy Technology Data Exchange (ETDEWEB)

    Halvorsen, E.N.

    1996-02-01

    Catalysts are very important in petrochemical processes. One of the properties that make crystalline, microporous materials attractive for catalytic purposes is their well-defined structure and ability to act as shape selective catalysts. This doctoral thesis presents the synthesis and characterization of a number of crystalline, microporous aluminophosphates and silicoaluminophosphates. 99 refs., 50 figs., 12 tabs.

  18. Development of chemical process for synthesis of polyunsaturated esters

    OpenAIRE

    Vera LÃcia Viana do Nascimento

    2014-01-01

    This work aimed to develop refining processes, chemical alcoholysis followed by separation of fatty acids using the complexation with urea technique for the synthesis of poly-unsaturated esters from waste of fish oils. The special crude fish oil was purchased from Company Campestre - SÃo Paulo. Initially this oil has undergone a process of physical and chemical refining. From the refined oil, an alcoholysis process was carried out to obtain the mixture of free fatty acids. From the hydrolyzed...

  19. Graphene: chemical approaches to the synthesis and modification

    Energy Technology Data Exchange (ETDEWEB)

    Grayfer, E D; Makotchenko, V G; Nazarov, Albert S; Kim, S J; Fedorov, Vladimir E

    2011-08-31

    Published data on the new carbon nanomaterial, graphene, are described systematically from the chemist's standpoint. The attention is focused on the chemical methods of the synthesis of graphene-like materials from various precursors: natural and expanded graphite, graphite oxide, graphite intercalation compounds, etc. Approaches to the chemical modification of the graphene plane by various reagents and routes for the preparation of colloidal dispersions of graphene are considered. The bibliography includes 220 references.

  20. Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Zhenzhong Guo

    2016-10-01

    Full Text Available The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclusion and future expectations are described herein.

  1. Synthesis of Novel Hydrocarbon Soluble Multifunctional Anionic Initiators: Tools for Synthesis of Novel Dendrimer and Molecular Brush Polymer Architectures

    Science.gov (United States)

    2015-02-09

    Synthesis of Novel Dendrimer and Molecular Brush Polymer Architectures. Research Area:7.4 The views, opinions and/or findings contained in this report...journals: Final Report: Synthesis of Novel Hydrocarbon Soluble Multifunctional Anionic Initiators: Tools for Synthesis of Novel Dendrimer and Molecular

  2. An Efficient, Green Chemical Synthesis of the Malaria Drug ...

    African Journals Online (AJOL)

    Results : A green-chemical synthesis of piperaquine is described that proceeds in 92 – 93 % overall yield. ... Keywords: ACTs, Dihydroartemisinin Piperaquine, Dihydroartemisinin, Green Chemistry, Malaria, ..... Mathers CD, Ezzati M, Lopez AD. ... Medicines Programme [Homepage on the Internet]. Geneva ... An Alternative.

  3. Microwave Technology--Applications in Chemical Synthesis

    Science.gov (United States)

    Microwave heating, being specific and instantaneous, is unique and has found a place for expeditious chemical syntheses. Specifically, the solvent-free reactions are convenient to perform and have advantages over the conventional heating protocols as summarized in the previous se...

  4. Synthesis, biological evaluation and molecular docking studies of ...

    African Journals Online (AJOL)

    Synthesis, biological evaluation and molecular docking studies of Mannich bases derived from 1, 3, 4-oxadiazole- 2-thiones as potential urease inhibitors. ... Mannich bases (5-17) were subjected to in silico screening as urease inhibitors, using crystal structure of urease (Protein Data Bank ID: 5FSE) as a model enzyme.

  5. Synthesis and molecular docking of new hydrazones derived from ...

    African Journals Online (AJOL)

    Synthesis and molecular docking of new hydrazones derived from ethyl isonipecotate and their biological activities. A Munir, Aziz-ur Rehman, M.A. Abbasi, S.Z. Siddiqui, A Nasir, S.G. Khan, S Rasool, S.A.A. Shah ...

  6. Molecular structure design and soft template synthesis of aza-, oxaaza- and thiaazamacrocyclic metal chelates in the gelatin matrix

    Directory of Open Access Journals (Sweden)

    Oleg V. Mikhailov

    2017-01-01

    Full Text Available The data about of soft template synthesis proceeding in gelatin matrices in [3d-element M(II ion – (N,S- or (N,O,S-ambidentate ligson – mono- or dicarbonyl ligson] systems, have been considered and discussed. The chemical nature of the final products of template synthesis formed under these specific conditions, has been compared with the chemical nature of the final products formed by template synthesis in solutions. It has been noted that in many cases, the nature and chemical composition of these products differ substantially. Specific features of the DFT calculated molecular structures of the macrocyclic compounds that can be formed due to the template synthesis in the systems indicated above, have been discussed, too. The review covers the period 1990–2015.

  7. High Molecular Weight Polymers in the New Chemicals Program

    Science.gov (United States)

    There are three categories or types of High Molecular Weight (HMW, 10,000 daltons) polymers typically reviewed by the New Chemicals Program: Soluble, insoluble, and water absorbing. Each of the three types are treated differently.

  8. Alternative fuels and chemicals from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1998-12-01

    A DOE/PETC funded study was conducted to examine the use of a liquid phase mixed alcohol synthesis (LPMAS) plant to produce gasoline blending ethers. The LPMAS plant was integrated into three utilization scenarios: a coal fed IGCC power plant, a petroleum refinery using coke as a gasification feedstock, and a standalone natural gas fed partial oxidation plant. The objective of the study was to establish targets for the development of catalysts for the LPMAS reaction. In the IGCC scenario, syngas conversions need only be moderate because unconverted syngas is utilized by the combined cycle system. A once through LPMAS plant achieving syngas conversions in the range of 38--49% was found to be suitable. At a gas hourly space velocity of 5,000 sL/Kg-hr and a methanol:isobutanol selectivity ratio of 1.03, the target catalyst productivity ranges from 370 to 460 g iBuOH/Kg-hr. In the petroleum refinery scenario, high conversions ({approximately}95%) are required to avoid overloading the refinery fuel system with low Btu content unconverted syngas. To achieve these high conversions with the low H{sub 2}/CO ratio syngas, a recycle system was required (because of the limit imposed by methanol equilibrium), steam was injected into the LPMAS reactor, and CO{sub 2} was removed from the recycle loop. At the most economical recycle ratio, the target catalyst productivity is 265 g iBuOH/Kg-hr. In the standalone LPMAS scenario, essentially complete conversions are required to achieve a fuel balanced plant. At the most economical recycle ratio, the target catalyst productivity is 285 g iBuOH/Kg-hr. The economics of this scenario are highly dependent on the cost of the natural gas feedstock and the location of the plant. For all three case scenarios, the economics of a LPMAS plant is marginal at current ether market prices. Large improvements over demonstrated catalyst productivity and alcohol selectivity are required.

  9. Molecular dynamics simulations and quantum chemical calculations ...

    African Journals Online (AJOL)

    Molecular dynamic simulation results indicate that the imidazoline derivative molecules uses the imidazoline ring to effectively adsorb on the surface of iron, with the alkyl hydrophobic tail forming an n shape (canopy like covering) at geometry optimization and at 353 K. The n shape canopy like covering to a large extent may ...

  10. Efficiency of Energy Transduction in a Molecular Chemical Engine

    OpenAIRE

    Sasaki, Kazuo; Kanada, Ryo; Amari, Satoshi

    2006-01-01

    A simple model of the two-state ratchet type is proposed for molecular chemical engines that convert chemical free energy into mechanical work and vice versa. The engine works by catalyzing a chemical reaction and turning a rotor. Analytical expressions are obtained for the dependences of rotation and reaction rates on the concentrations of reactant and product molecules, from which the performance of the engine is analyzed. In particular, the efficiency of energy transduction is discussed in...

  11. Hexagonal ferrite powder synthesis using chemical coprecipitation

    International Nuclear Information System (INIS)

    Hsiang, H.-I; Yao, R.-Q.

    2007-01-01

    The formation mechanism of 3BaO.2CoO.12Fe 2 O 3 (Co 2 Z), 2BaO.2CoO.6Fe 2 O 3 (Co 2 Y) and BaO.6Fe 2 O 3 (BaM) powders were prepared using chemical coprecipitation methods in this study using X-ray diffraction (XRD), thermo-gravimetry (TG), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR). It was found that the BaM phase was formed directly through the reaction of the preceding ε-Fe 2 O 3 and amorphous BaCO 3 for BaM precursor. For the Co 2 Y precursor, the intermediate phase, BaM, was obtained through the reaction of the earlier formed BaFe 2 O 4 and α-Fe 2 O 3 . The Co 2 Y phase was obtained through a BaM and BaFe 2 O 4 reaction. However, for the Co 2 Z precursors, the BaM phase was obtained directly from the BaCO 3 and amorphous iron hydroxide reaction, with no α-Fe 2 O 3 and BaFe 2 O 4 formed as intermediates. Co 2 Z phase was obtained through the reaction of the two previous formed BaM and Co 2 Y phases

  12. Supersonic molecular beam experiments on surface chemical reactions.

    Science.gov (United States)

    Okada, Michio

    2014-10-01

    The interaction of a molecule and a surface is important in various fields, and in particular in complex systems like biomaterials and their related chemistry. However, the detailed understanding of the elementary steps in the surface chemistry, for example, stereodynamics, is still insufficient even for simple model systems. In this Personal Account, I review our recent studies of chemical reactions on single-crystalline Cu and Si surfaces induced by hyperthermal oxygen molecular beams and by oriented molecular beams, respectively. Studies of oxide formation on Cu induced by hyperthermal molecular beams demonstrate a significant role of the translational energy of the incident molecules. The use of hyperthermal molecular beams enables us to open up new chemical reaction paths specific for the hyperthermal energy region, and to develop new methods for the fabrication of thin films. On the other hand, oriented molecular beams also demonstrate the possibility of understanding surface chemical reactions in detail by varying the orientation of the incident molecules. The steric effects found on Si surfaces hint at new ways of material fabrication on Si surfaces. Controlling the initial conditions of incoming molecules is a powerful tool for finely monitoring the elementary step of the surface chemical reactions and creating new materials on surfaces. Copyright © 2014 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Temperature lowering in cryogenic chemical-synthesis techniques and system

    International Nuclear Information System (INIS)

    Martinez, H.E.; Nelson, T.O.; Vikdal, L.N.

    1993-01-01

    When evaluating a chemical synthesis process for a reaction that occurs on the cryogenically cooled walls, it is sometimes necessary to reduce the wall temperatures to enhance the chemical process. To evaluate the chemical process at lower than atmospheric boiling of liquid nitrogen, we built a system and used it to reduce the temperature of the liquid nitrogen. The technique of lowering the liquid nitrogen temperature by reducing the pressure of the boil-off is established knowledge. This paper presents the engineering aspects of the system, design features, equipment requirements, methods of control, and results of the chemical synthesis. The heat input to the system was ∼400 watts, placing a relatively large demand on the pumping system. Our system is a scale-up of the small laboratory experiment, and it provides the information needed to design an effective system. The major problem encountered was the large quantity of liquid escaping the system during the processing, placing a large gas load on the vacuum system

  14. Mapping of Drug-like Chemical Universe with Reduced Complexity Molecular Frameworks.

    Science.gov (United States)

    Kontijevskis, Aleksejs

    2017-04-24

    The emergence of the DNA-encoded chemical libraries (DEL) field in the past decade has attracted the attention of the pharmaceutical industry as a powerful mechanism for the discovery of novel drug-like hits for various biological targets. Nuevolution Chemetics technology enables DNA-encoded synthesis of billions of chemically diverse drug-like small molecule compounds, and the efficient screening and optimization of these, facilitating effective identification of drug candidates at an unprecedented speed and scale. Although many approaches have been developed by the cheminformatics community for the analysis and visualization of drug-like chemical space, most of them are restricted to the analysis of a maximum of a few millions of compounds and cannot handle collections of 10 8 -10 12 compounds typical for DELs. To address this big chemical data challenge, we developed the Reduced Complexity Molecular Frameworks (RCMF) methodology as an abstract and very general way of representing chemical structures. By further introducing RCMF descriptors, we constructed a global framework map of drug-like chemical space and demonstrated how chemical space occupied by multi-million-member drug-like Chemetics DNA-encoded libraries and virtual combinatorial libraries with >10 12 members could be analyzed and mapped without a need for library enumeration. We further validate the approach by performing RCMF-based searches in a drug-like chemical universe and mapping Chemetics library selection outputs for LSD1 targets on a global framework chemical space map.

  15. Molecular effects: interactions with chemicals and viruses

    International Nuclear Information System (INIS)

    Hanawalt, P.C.

    1980-01-01

    Research focused upon an understanding of the cellular responses to the molecular effects of ionizing radiation should be an essential program component in the Federal Strategy for Research into the Biological Effects of Ionizing Radiation. Although we know that DNA is a principal target molecule for some highly significant biological effects of ionizing radiation, we need to learn which other target substances such as membrane components may also be important. Most of the emphasis should continue to be on DNA effects and highest priority should be assigned to the identification of the complete spectrum of products produced in DNA. Once the lesions are known we can proceed to determine how these behave as blocks to replication and transcription or as modulators on the fidelity of these crucial processes. Considerable work should be done on the repair of these lesions. High priority should be given to the search for mutants in mammalian cell systems with evident defects in the processing of specific lesions. Viruses should provide important tools for the research in this area, as probes for host cell repair responses and also for the isolation of mutants. Furthermore, it is important to consider the interaction of viruses and ionizing radiation with regard to possible modulating effects on repair processes and tumorigenesis. Finally we must consider the important problem of the modification of repair responses by environmental factors

  16. "Intelligent" design of molecular materials: Understanding the concepts of design in supramolecular synthesis of network solids

    Science.gov (United States)

    Moulton, Brian D.

    This work endeavors to delineate modern paradigms for crystal engineering, i.e. the design and supramolecular synthesis of functional molecular materials. Paradigms predicated on an understanding of the geometry of polygons and polyhedra are developed. The primary focus is on structural determination by single crystal X-ray crystallography, structural interpretation using a suite of graphical visualization and molecular modeling software, and on the importance of proper graphical representation in the presentation and explanation of crystal structures. A detailed analysis of a selected series of crystal structures is presented. The reduction of these molecular networks to schematic representations that illustrate their fundamental connectivity facilitates the understanding of otherwise complex supramolecular solids. Circuit symbols and Schlafli notation are used to describe the network topologies, which enables networks of different composition and metrics to be easily compared. This reveals that molecular orientations in the crystals and networks are commensurate with networks that can be derived from spherical close packed lattices. The development of a logical design strategy for a new class of materials based on our understanding of the chemical composition and topology of these networks is described. The synthesis and crystal structure of a series of new materials generated by exploitation of this design strategy is presented, in addition to a detailed analysis of the topology of these materials and their relationship to a 'parent' structure. In summary, this dissertation demonstrates that molecular polygons can self-assemble at their vertexes to produce molecular architectures and crystal structures that are consistent with long established geometric dogma. The design strategy represents a potentially broad ranging approach to the design of nanoporous structures from a wide range of chemical components that are based on molecular shape rather than chemical

  17. Synthesis, molecular and crystalline architectures, and properties of ...

    Indian Academy of Sciences (India)

    The construction1 of coordination compounds of cobalt(II) of different nuclearities is the centre of attrac- tion due to interesting structural and physico-chemical properties.1–5 ... Design SQUID MPMS-XL magnetometer working in the 2–300 K range. ..... Complex 1 adopts a molecular architecture cor- responding to the gross ...

  18. The Molecular Industrial Revolution: Automated Synthesis of Small Molecules.

    Science.gov (United States)

    Trobe, Melanie; Burke, Martin D

    2018-04-09

    Today we are poised for a transition from the highly customized crafting of specific molecular targets by hand to the increasingly general and automated assembly of different types of molecules with the push of a button. Creating machines that are capable of making many different types of small molecules on demand, akin to that which has been achieved on the macroscale with 3D printers, is challenging. Yet important progress is being made toward this objective with two complementary approaches: 1) Automation of customized synthesis routes to different targets by machines that enable the use of many reactions and starting materials, and 2) automation of generalized platforms that make many different targets using common coupling chemistry and building blocks. Continued progress in these directions has the potential to shift the bottleneck in molecular innovation from synthesis to imagination, and thereby help drive a new industrial revolution on the molecular scale. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A reversible, unidirectional molecular rotary motor driven by chemical energy

    NARCIS (Netherlands)

    Fletcher, SP; Dumur, F; Pollard, MM; Feringa, BL

    2005-01-01

    With the long-term goal of producing nanometer-scale machines, we describe here the unidirectional rotary motion of a synthetic molecular structure fueled by chemical conversions. The basis of the rotation is the movement,of a phenyl rotor relative to a naphthyl stator about a single bond axle. The

  20. Comparison of traditional physico-chemical methods and molecular ...

    African Journals Online (AJOL)

    This study was aim to review the efficiency of molecular markers and traditional physico-chemical methods for the identification of basmati rice. The study involved 44 promising varieties of Indica rices collected from geographically distant places and adapted to irrigated and aerobic agro-ecosystems. Quality data for ...

  1. Chemical Dynamics, Molecular Energetics, and Kinetics at the Synchrotron

    International Nuclear Information System (INIS)

    Leone, Stephen R.; Ahmed, Musahid; Wilson, Kevin R.

    2010-01-01

    Scientists at the Chemical Dynamics Beamline of the Advanced Light Source in Berkeley are continuously reinventing synchrotron investigations of physical chemistry and chemical physics with vacuum ultraviolet light. One of the unique aspects of a synchrotron for chemical physics research is the widely tunable vacuum ultraviolet light that permits threshold ionization of large molecules with minimal fragmentation. This provides novel opportunities to assess molecular energetics and reaction mechanisms, even beyond simple gas phase molecules. In this perspective, significant new directions utilizing the capabilities at the Chemical Dynamics Beamline are presented, along with an outlook for future synchrotron and free electron laser science in chemical dynamics. Among the established and emerging fields of investigations are cluster and biological molecule spectroscopy and structure, combustion flame chemistry mechanisms, radical kinetics and product isomer dynamics, aerosol heterogeneous chemistry, planetary and interstellar chemistry, and secondary neutral ion-beam desorption imaging of biological matter and materials chemistry.

  2. Molecular dynamics simulations of solutions at constant chemical potential

    Science.gov (United States)

    Perego, C.; Salvalaglio, M.; Parrinello, M.

    2015-04-01

    Molecular dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, which range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, which influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a grand-canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work, we propose the Constant Chemical Potential Molecular Dynamics (CμMD) method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the CμMD method to the paradigmatic case of urea crystallization in aqueous solution. As a result, we have been able to study crystal growth dynamics under constant supersaturation conditions and to extract growth rates and free-energy barriers.

  3. Dihydroazulene Photochromism:Synthesis, Molecular Electronics and Hammett Correlations

    DEFF Research Database (Denmark)

    Broman, Søren Lindbæk

    This thesis describes the development of a versatile synthetic protocol for preparation of a large selection of dihydroazulenes (DHAs) with both electron withdrawing and donating groups. By UV-Vis and NMR spectroscopies and even in a single-molecule junction, their ability to undergo a light...... will be discussed in detail. The second chapter describes the design and synthesis of DHA/VHFs intended for use in molecular electronics and their solution and single-molecule junction switching properties. By the expansion of the recently reported procedure for functionalization of this system by Suzuki cross...

  4. New 1,2,4-triazine bearing compounds: molecular modeling, synthesis and biotesting

    Directory of Open Access Journals (Sweden)

    Negrutska V. V.

    2009-12-01

    Full Text Available Aim. To enlarge a spectrum of biologically active compounds in the series of the 1,2,4-triazino[5,6-b] [1,4]benzothiazine (1,2,4-TBT derivatives and reveal among them efficient inhibitors of RNA synthesis Methods. The methods of structure optimization of the 3-oxo-1,2,4-TBT by fragment-oriented substitution, the molecular doking of new structures in a virtual target, the rational chemical synthesis of the theoretically predicted compounds and their testing in the system of transcription in vitro. Results. The series of 1,2,4-TBT derivatives with substituents in the benzene and triazine cycles of a base molecule were synthesized. The testing of synthesized compounds in the in vitro transcription system directed by T7 RNA polymerase revealed the structure- and concentration-dependent inhibition of the RNA synthesis by some of these compounds. The experimental and virtual screening data for all investigated compounds have a good correlation. It was found that most effective derivative is the 3-oxo-8-butyl-1,2,4-TBT which completely inhibited transcription at the concentration of 6 mg/ml. Conclusions. The biotesting results allow us to assume that the inhibition of RNA synthesis is caused by binding of the 3-oxo- 8-butyl-1,2,4-TBT to both free RNA polymerase molecules and those including in a transcriptional complex with DNA

  5. Chemical sensors based on molecularly modified metallic nanoparticles

    International Nuclear Information System (INIS)

    Haick, Hossam

    2007-01-01

    This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

  6. Molecularly Imprinted Polymer Beads-Synthesis, Evaluation and Applications

    OpenAIRE

    Zhou, Tongchang

    2016-01-01

    Molecularly imprinted polymers (MIPs) are artificial receptors designed for the selective recognition of template molecules. These polymers have been applied in analytical separations, as chemical sensors and in drug delivery system due to their low cost and high stability. In recent years MIP beads, especially those with good selectivity in aqueous solution, have become attractive as they can be potentially used as selective adsorbents for the solid phase extraction (SPE) and chromatographic...

  7. Microbial chemical factories: recent advances in pathway engineering for synthesis of value added chemicals.

    Science.gov (United States)

    Dhamankar, Himanshu; Prather, Kristala L J

    2011-08-01

    The dwindling nature of petroleum and other fossil reserves has provided impetus towards microbial synthesis of fuels and value added chemicals from biomass-derived sugars as a renewable resource. Microbes have naturally evolved enzymes and pathways that can convert biomass into hundreds of unique chemical structures, a property that can be effectively exploited for their engineering into Microbial Chemical Factories (MCFs). De novo pathway engineering facilitates expansion of the repertoire of microbially synthesized compounds beyond natural products. In this review, we visit some recent successes in such novel pathway engineering and optimization, with particular emphasis on the selection and engineering of pathway enzymes and balancing of their accessory cofactors. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Molecular mechanism of reduction in pregnenolone synthesis by cigarette smoke

    International Nuclear Information System (INIS)

    Bose, Mahuya; Whittal, Randy M.; Gairola, C. Gary; Bose, Himangshu S.

    2008-01-01

    Steroidogenic acute regulatory protein (StAR) facilitates the movement of cholesterol from the outer to inner mitochondrial membrane for the synthesis of pregnenolone. Here, we investigated the molecular mechanism of the reduction of pregnenolone synthesis by cigarette smoke condensate (CSC). Pre-exposure or post-exposure of cells with CSC led to reduced pregnenolone synthesis, in a fashion similar to its effect on isolated mitochondria. However, there was no difference in the expression of 30 kDa StAR in cells treated with moderately concentrated CSC by either regimen. The active form of 37 kDa StAR is degraded easily suggesting that the continuous presence of CSC reduces StAR expression. Mitochondrial import of 35 S-methionine-labeled StAR followed by extraction of the StAR-mitochondrial complex with 1% digitonin showed similarly sized complexes in the CSC-treated and untreated mitochondria. Further analysis by sucrose density gradient centrifugation showed a specific complex, 'complex 2', in the untreated mitochondria but absent in the CSC-treated mitochondria. Mass spectrometric analysis revealed that complex 2 is the outer mitochondrial protein, VDAC1. Knockdown of VDAC1 expression by siRNA followed by co-transfection with StAR resulted in a lack of pregnenolone synthesis and 37 kDa StAR expression with reduced expression of the intermediate, 32 kDa StAR. Taken together, these results suggest that in the absence of VDAC1, active StAR expression is reduced indicating that VDAC1 expression is essential for StAR activity. In the absence of VDAC1-StAR interaction, cholesterol cannot be transported into mitochondria; thus the interaction with VDAC1 is a mandatory step for initiating steroidogenesis

  9. Total chemical synthesis of histones and their analogs, assisted by native chemical ligation and palladium complexes.

    Science.gov (United States)

    Maity, Suman Kumar; Jbara, Muhammad; Mann, Guy; Kamnesky, Guy; Brik, Ashraf

    2017-11-01

    Chemical synthesis of histones allows precise control of the installation of post-translational modifications via the coupling of derivatized amino acids. Shortcomings of other approaches for obtaining modified histones for epigenetic studies include heterogeneity of the obtained product and difficulties in incorporating multiple modifications on the same histone. In this protocol, unprotected peptide fragments are prepared by Fmoc solid-phase synthesis and coupled in aqueous buffers via native chemical ligation (NCL; in NCL, a peptide bond is formed between a peptide with an N-terminal Cys and another peptide having a C-terminal thioester). This task is challenging, with obstacles relating to the preparation and ligation of hydrophobic peptides, as well as the requirement for multiple purification steps due to protecting-group manipulations during the polypeptide assembly process. To address this, our approach uses an easily removable solubilizing tag for the synthesis and ligation of hydrophobic peptides, as well as a more efficient and better-yielding method to remove Cys-protecting groups that uses palladium chemistry (specifically [Pd(allyl)Cl] 2 and PdCl 2 complexes). The utility of this approach is demonstrated in the syntheses of ubiquitinated H2B at Lys34, phosphorylated H2A at Tyr57 and unmodified H4. Each of these analogs can be prepared in milligram quantities within ∼20-30 d.

  10. Recent Developments in Chemical Synthesis with Biocatalysts in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Mahesh K. Potdar

    2015-09-01

    Full Text Available Over the past decade, a variety of ionic liquids have emerged as greener solvents for use in the chemical manufacturing industries. Their unique properties have attracted the interest of chemists worldwide to employ them as replacement for conventional solvents in a diverse range of chemical transformations including biotransformations. Biocatalysts are often regarded as green catalysts compared to conventional chemical catalysts in organic synthesis owing to their properties of low toxicity, biodegradability, excellent selectivity and good catalytic performance under mild reaction conditions. Similarly, a selected number of specific ionic liquids can be considered as greener solvents superior to organic solvents owing to their negligible vapor pressure, low flammability, low toxicity and ability to dissolve a wide range of organic and biological substances, including proteins. A combination of biocatalysts and ionic liquids thus appears to be a logical and promising opportunity for industrial use as an alternative to conventional organic chemistry processes employing organic solvents. This article provides an overview of recent developments in this field with special emphasis on the application of more sustainable enzyme-catalyzed reactions and separation processes employing ionic liquids, driven by advances in fundamental knowledge, process optimization and industrial deployment.

  11. Soft chemical synthesis of silicon nanosheets and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Hideyuki; Ikuno, Takashi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2016-12-15

    Two-dimensional silicon nanomaterials are expected to show different properties from those of bulk silicon materials by virtue of surface functionalization and quantum size effects. Since facile fabrication processes of large area silicon nanosheets (SiNSs) are required for practical applications, a development of soft chemical synthesis route without using conventional vacuum processes is a challenging issue. We have recently succeeded to prepare SiNSs with sub-nanometer thicknesses by exfoliating layered silicon compounds, and they are found to be composed of crystalline single-atom-thick silicon layers. In this review, we present the synthesis and modification methods of SiNSs. These SiNSs have atomically flat and smooth surfaces due to dense coverage of organic moieties, and they are easily self-assembled in a concentrated state to form a regularly stacked structure. We have also characterized the electron transport properties and the electronic structures of SiNSs. Finally, the potential applications of these SiNSs and organic modified SiNSs are also reviewed.

  12. An optimized chemical synthesis of human relaxin-2.

    Science.gov (United States)

    Barlos, Kostas K; Gatos, Dimitrios; Vasileiou, Zoe; Barlos, Kleomenis

    2010-04-01

    Human gene 2 relaxin (RLX) is a member of the insulin superfamily and is a multi-functional factor playing a vital role in pregnancy, aging, fibrosis, cardioprotection, vasodilation, inflammation, and angiogenesis. RLX is currently applied in clinical trials to cure among others acute heart failure, fibrosis, and preeclampsia. The synthesis of RLX by chemical methods is difficult because of the insolubility of its B-chain and the required laborious and low yielding site-directed combination of its A (RLXA) and B (RLXB) chains. We report here that oxidation of the Met(25) residue of RLXB improves its solubility, allowing its effective solid-phase synthesis and application in random interchain combination reactions with RLXA. Linear Met(O)(25)-RLX B-chain (RLXBO) reacts with a mixture of isomers of bicyclic A-chain (bcRLXA) giving exclusively the native interchain combination. Applying this method Met(O)(25)-RLX (RLXO) was obtained in 62% yield and was easily converted to RLX in 78% yield, by reduction with ammonium iodide. Copyright (c) 2010 European Peptide Society and John Wiley & Sons, Ltd.

  13. Bioinspired chemical synthesis of monomeric and dimeric stephacidin A congeners

    Science.gov (United States)

    Mukai, Ken; de Sant'ana, Danilo Pereira; Hirooka, Yasuo; Mercado-Marin, Eduardo V.; Stephens, David E.; Kou, Kevin G. M.; Richter, Sven C.; Kelley, Naomi; Sarpong, Richmond

    2018-01-01

    Stephacidin A and its congeners are a collection of secondary metabolites that possess intriguing structural motifs. They stem from unusual biosynthetic sequences that lead to the incorporation of a prenyl or reverse-prenyl group into a bicyclo[2.2.2]diazaoctane framework, a chromene unit or the vestige thereof. To complement biosynthetic studies, which normally play a significant role in unveiling the biosynthetic pathways of natural products, here we demonstrate that chemical synthesis can provide important insights into biosynthesis. We identify a short total synthesis of congeners in the reverse-prenylated indole alkaloid family related to stephacidin A by taking advantage of a direct indole C6 halogenation of the related ketopremalbrancheamide. This novel strategic approach has now made possible the syntheses of several natural products, including malbrancheamides B and C, notoamides F, I and R, aspergamide B, and waikialoid A, which is a heterodimer of avrainvillamide and aspergamide B. Our approach to the preparation of these prenylated and reverse-prenylated indole alkaloids is bioinspired, and may also inform the as-yet undetermined biosynthesis of several congeners.

  14. Bayesian molecular design with a chemical language model

    Science.gov (United States)

    Ikebata, Hisaki; Hongo, Kenta; Isomura, Tetsu; Maezono, Ryo; Yoshida, Ryo

    2017-04-01

    The aim of computational molecular design is the identification of promising hypothetical molecules with a predefined set of desired properties. We address the issue of accelerating the material discovery with state-of-the-art machine learning techniques. The method involves two different types of prediction; the forward and backward predictions. The objective of the forward prediction is to create a set of machine learning models on various properties of a given molecule. Inverting the trained forward models through Bayes' law, we derive a posterior distribution for the backward prediction, which is conditioned by a desired property requirement. Exploring high-probability regions of the posterior with a sequential Monte Carlo technique, molecules that exhibit the desired properties can computationally be created. One major difficulty in the computational creation of molecules is the exclusion of the occurrence of chemically unfavorable structures. To circumvent this issue, we derive a chemical language model that acquires commonly occurring patterns of chemical fragments through natural language processing of ASCII strings of existing compounds, which follow the SMILES chemical language notation. In the backward prediction, the trained language model is used to refine chemical strings such that the properties of the resulting structures fall within the desired property region while chemically unfavorable structures are successfully removed. The present method is demonstrated through the design of small organic molecules with the property requirements on HOMO-LUMO gap and internal energy. The R package iqspr is available at the CRAN repository.

  15. Molecular codes in biological and chemical reaction networks.

    Directory of Open Access Journals (Sweden)

    Dennis Görlich

    Full Text Available Shannon's theory of communication has been very successfully applied for the analysis of biological information. However, the theory neglects semantic and pragmatic aspects and thus cannot directly be applied to distinguish between (bio- chemical systems able to process "meaningful" information from those that do not. Here, we present a formal method to assess a system's semantic capacity by analyzing a reaction network's capability to implement molecular codes. We analyzed models of chemical systems (martian atmosphere chemistry and various combustion chemistries, biochemical systems (gene expression, gene translation, and phosphorylation signaling cascades, an artificial chemistry, and random reaction networks. Our study suggests that different chemical systems possess different semantic capacities. No semantic capacity was found in the model of the martian atmosphere chemistry, the studied combustion chemistries, and highly connected random networks, i.e. with these chemistries molecular codes cannot be implemented. High semantic capacity was found in the studied biochemical systems and in random reaction networks where the number of second order reactions is twice the number of species. We conclude that our approach can be applied to evaluate the information processing capabilities of a chemical system and may thus be a useful tool to understand the origin and evolution of meaningful information, e.g. in the context of the origin of life.

  16. Synthesis of molecular complexes for small molecule activation

    International Nuclear Information System (INIS)

    Andrez, Julie

    2016-01-01

    The redox chemistry of f-elements is drawing the attention of inorganic chemists due to their unusual reaction pathways. Notably low-valent f-element complexes have been shown to be able to activate small molecules such as CO_2 and N_2 in mild conditions. Compared to d-block metals, f-elements present a coordination chemistry dominated by electrostatic interactions and steric constraints. Molecular complexes of f-elements could thus provide new catalytic routes to transform small molecules into valuable chemicals. However the redox chemistry of low valent f-elements is dominated by single-electron transfers while the reductions of CO_2 and N_2 require multi-electronic processes. Accordingly the first approach of this PhD work was the use of redox active ligands as electron reservoir to support f-element centres increasing the electron number available for reduction events. The coordination of uranium with tridentate Schiff base ligand was investigated and led to isolation of a dinuclear electron-rich species able to undertake up to eight-electron reduction combining the redox activity of the ligands and the uranium centres. In order to obtain electron-rich compounds potentially able to polarize the C=O bond of CO_2, the synthesis of hetero-bimetallic species supported by salophen Schiff base ligand was also studied. In a second approach we have used bulky ligands with strong donor-character to tune the reducing abilities of low valent f-elements. In this case a bimolecular electron-transfer process is often observed. The reactivity of the U(III) siloxid complex [U(OSi(OtBu)_3)_4K] was further investigated. Notably, reaction with Ph_3PS led to the formation of a terminal U(IV) sulfide complex with multiple U-S bond which was analysed by DFT studies to better understand the bonding nature. Preliminary studies on the role of the counter-cation (M) in the system [U(OSi(OtBu)_3)_4M] on the outcome of the reactivity with CS_2 and CO_2 have also been performed. The

  17. Control of molecular weight distribution in synthesis of poly(2-hydroxyethyl methacrylate) using ultrasonic irradiation.

    Science.gov (United States)

    Kubo, Masaki; Kondo, Takayuki; Matsui, Hideki; Shibasaki-Kitakawa, Naomi; Yonemoto, Toshikuni

    2018-01-01

    Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized using ultrasonic irradiation without any chemical initiator. The effect of the ultrasonic power intensity on the time course of the conversion to polymer, the number average molecular weight, and the polydispersity were investigated in order to synthesize a polymer with a low molecular weight distribution (i.e., low polydispersity). The conversion to polymer increased with time. A higher ultrasonic power intensity resulted in a faster reaction rate. The number average molecular weight increased during the early stage of the reaction and then gradually decreased with time. A higher ultrasonic intensity resulted in a faster degradation rate of the polymer. The polydispersity decreased with time. This was because the degradation rate of a polymer with a higher molecular weight was faster than that of a polymer with a lower molecular weight. A polydispersity below 1.3 was obtained under ultrasonic irradiation. By changing the ultrasonic power intensity during the reaction, the number average molecular weight can be controlled while maintaining low polydispersity. When the ultrasonic irradiation was halted, the reactions stopped and the number average molecular weight and polydispersity did not change. On the basis of the experimental results, a kinetic model for synthesis of PHEMA under ultrasonic irradiation was constructed considering both polymerization and polymer degradation. The kinetic model was in good agreement with the experimental results for the time courses of the conversion to polymer, the number average molecular weight, and the polydispersity for various ultrasonic power intensities. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Synthesis, structural characterization and quantum chemical studies of silicon-containing benzoic acid derivatives

    Science.gov (United States)

    Zaltariov, Mirela-Fernanda; Cojocaru, Corneliu; Shova, Sergiu; Sacarescu, Liviu; Cazacu, Maria

    2016-09-01

    The present paper is concerned with the synthesis and molecular structure investigation of two new benzoic acid derivatives having trimethylsilyl tails, 4-((trimethylsilyl)methoxy) and 4-(3-(trimethylsilyl)propoxy)benzoic acids. The structures of the novel compounds have been confirmed by X-ray crystallography, Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H and 13C NMR). The theoretical studies of molecules were conducted by using the quantum chemical methods, such as Density Functional Theory (DFT B3LYP/6-31 + G**), Hartree-Fock (HF/6-31 + G**) and semiempirical computations (PM3, PM6 and PM7). The optimized molecular geometries have been found to be in good agreement with experimental structures resulted from the X-ray diffraction. The maximum electronic absorption bands observed at 272-287 nm (UV-vis spectra) have been assigned to π → π* transitions, which were in reasonable agreement with the time dependent density functional theory (TD-DFT) calculations. The computed vibrational frequencies by DFT method were assigned and compared with the experimental FTIR spectra. The mapped electrostatic potentials revealed the reactive sites, which corroborated the observation of the dimer supramolecular structures formed in the crystals by hydrogen-bonding. The energies of frontier molecular orbitals (HOMO and LUMO), energy gap, dipole moment and molecular descriptors for the new compounds were calculated and discussed.

  19. Chemical Modification of Semiconductor Surfaces for Molecular Electronics.

    Science.gov (United States)

    Vilan, Ayelet; Cahen, David

    2017-03-08

    Inserting molecular monolayers within metal/semiconductor interfaces provides one of the most powerful expressions of how minute chemical modifications can affect electronic devices. This topic also has direct importance for technology as it can help improve the efficiency of a variety of electronic devices such as solar cells, LEDs, sensors, and possible future bioelectronic ones. The review covers the main aspects of using chemistry to control the various aspects of interface electrostatics, such as passivation of interface states and alignment of energy levels by intrinsic molecular polarization, as well as charge rearrangement with the adjacent metal and semiconducting contacts. One of the greatest merits of molecular monolayers is their capability to form excellent thin dielectrics, yielding rich and unique current-voltage characteristics for transport across metal/molecular monolayer/semiconductor interfaces. We explain the interplay between the monolayer as tunneling barrier on the one hand, and the electrostatic barrier within the semiconductor, due to its space-charge region, on the other hand, as well as how different monolayer chemistries control each of these barriers. Practical tools to experimentally identify these two barriers and distinguish between them are given, followed by a short look to the future. This review is accompanied by another one, concerning the formation of large-area molecular junctions and charge transport that is dominated solely by molecules.

  20. SYNTHESIS AND CHARACTERIZATION OF NEW STABILIZERS WITH OPTIMAL MOLECULAR WEIGHT

    Institute of Scientific and Technical Information of China (English)

    Jiang-qing Pan

    2001-01-01

    Over 2 × l08 tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stabilizers to polymer remains the most convenient and effective way of enhancing polymer life and performance. In this article, a series of effective stabilizers with optimal molecular weight (MW), including common, monomeric and polymeric stabilizers (antioxidant and light stabilizer) were synthesized using isocyanation, controlled isocyanation, hydrosilylation, epoxide addition, macroreaction of stabilizing functional compounds and polymerization of monomeric stabilizers. The sructure and performance of these new stabilizers were characterized by using IR, NMR, MS, UV-spectra, XPS and elemental analysis. The current development of stabilizer synthesis was also reviewed.``

  1. Synthesis and Surface-Specific Analysis of Molecular Constituents Relevant to Biogenic Secondary Organic Aerosol Material

    Science.gov (United States)

    Be, A. G.; Upshur, M. A.; Chase, H. M.; Geiger, F.; Thomson, R. J.

    2017-12-01

    Secondary organic aerosol (SOA) particles formed from the oxidation of biogenic volatile organic compounds (BVOCs) remain a principal, yet elusive, class of airborne particulate matter that impacts the Earth's radiation budget. Given the characteristic molecular complexity comprising biogenic SOA particles, chemical information selective to the gas-aerosol interface may be valuable in the investigation of such systems, as surface considerations likely dictate the phenomena driving particle evolution mechanisms and climate effects. In particular, cloud activation processes may be parameterized using the surface tension depression that coincides with partitioning of surface-active organic species to the gas-droplet interface. However, the extent to which surface chemical processes, such as cloud droplet condensation, are influenced by the chemical structure and reactivity of individual surface-active molecules in SOA particles is largely unknown. We seek to study terpene-derived organic species relevant to the surfaces of biogenic SOA particles via synthesis of putative oxidation products followed by analysis using surface-selective physicochemical measurements. Using dynamic surface tension measurements, considerable differences are observed in the surface tension depression of aqueous pendant droplets that contain synthetically prepared ozonolysis products derived from abundant terpene precursors. Furthermore, sum frequency generation spectroscopy is utilized for comparison of the surface vibrational spectral responses of synthesized reference compounds with those observed for laboratory aerosol toward probing the surface composition of SOA material. Such ongoing findings highlight the underlying importance of molecular structure and reactivity when considering the surface chemistry of biogenic terpene-derived atmospheric aerosols.

  2. New approach for direct chemical synthesis of hexagonal Co nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Abel, Frank M., E-mail: fabel@udel.edu [Physics and Astronomy, University of Delaware (United States); Tzitzios, Vasilis [Institute of Nanoscience and Nanotechnology, NCSR, Demokritos (Greece); Hadjipanayis, George C. [Physics and Astronomy, University of Delaware (United States)

    2016-02-15

    In this paper, we explore the possibility of producing hexagonal Cobalt nanoparticles, with high saturation magnetization by direct chemical synthesis. The nanoparticles were synthesized by reduction of anhydrous cobalt (II) chloride by NaBH{sub 4} in tetraglyme at temperatures in the range of 200–270 °C under a nitrogen–hydrogen atmosphere. The reactions were done at high temperatures to allow for the formation of as-made hexagonal cobalt. The size of the particles was controlled by the addition of different surfactants. The best magnetic properties so far were obtained on spherical hexagonal Co nanoparticles with an average size of 45 nm, a saturation magnetization of 143 emu/g and coercivity of 500 Oe. the saturation magnetization and coercivity were further improved by annealing the Co nanoparticles leading to saturation magnetization of 160 emu/g and coercivity of 540 Oe. - Highlights: • We synthesized hexagonal cobalt nanoparticles by a new wet chemical method. • We considered the effects of different surfactants on particles magnetic properties. • The as-made Co nanoparticles had magnetic properties of 143 emu/g and 500 Oe. • After annealing magnetic properties of 160 emu/g and 540 Oe were obtained.

  3. Chemical protection and sensitization to ionizing radiation:molecular investigations

    International Nuclear Information System (INIS)

    Badiello, R.

    1980-01-01

    Chemical radioprotection and radiosensitization are induced by the presence of certain chemical compounds, which reduce or enhance the effect of ionizing radiation on living organisms. Such substances are either naturally present or may be artificially introduced in the living cells. Chemical radioprotectors are interesting for possible application in the health protection of both professionally exposed workers and patients treated by radiation for diagnostic and thereapeutic purposes. Interest in chemical radiosensitization has increased recently because of its potential application in the radiotherapy of tumours. Both radioprotection and radiosensitization occur by means of complicated mechanisms, which at first correspond to very fast reactions. The mechanism of the interaction between such substances and radiation-induced biological radicals has been investigated by means of pulse radiolysis and rapid mixing techniques. Examples of the application of these techniques are given to illustrate how information has been obtained on the molecular basis of radiation chemical modi-fication at the cellular level. In particular some interactions between model systems of biological interest (DNA, DNA components, enzymes, amino acids, etc.) and sulphur-containing radioprotectors (glutathione, cysteine, etc.) and/or electroaffinic radiosensitizers, are described. (H.K.)

  4. Eco-friendly synthesis, physicochemical studies, biological assay and molecular docking of steroidal oxime-ethers

    Science.gov (United States)

    Alam, Mahboob; Lee, Dong-Ung

    2015-01-01

    The aim of this study was to report the synthesis of biologically active compounds; 7-(2′-aminoethoxyimino)-cholest-5-ene (4), a steroidal oxime-ether and its derivatives (5, 6) via a facile microwave assisted solvent free reaction methodology. This new synthetic, eco-friendly, sustainable protocol resulted in a remarkable improvement in the synthetic efficiency (85-93 % yield) and high purity using basic alumina. The synthesized compounds were screened for their antibacterial against six bacterial strains by disc diffusion method and antioxidant potential by DPPH assay. The binding capabilities of a compound 6 exhibiting good antibacterial potential were assessed on the basis of molecular docking studies and four types of three-dimensional molecular field descriptors. Moreover the structure-antimicrobial activity relationships were studied using some physicochemical and quantum-chemical parameters with GAMESS interface as well as WebMO Job Manager by using the basic level of theory. Hence, this synthetic approach is believed to provide a better scope for the synthesis of steroidal oxime-ether analogues and will be a more practical alternative to the presently existing procedures. Moreover, detailed in silico docking studies suggested the plausible mechanism of steroidal oxime-ethers as effective antimicrobial agents. PMID:27330525

  5. Boron nitride ceramics from molecular precursors: synthesis, properties and applications.

    Science.gov (United States)

    Bernard, Samuel; Salameh, Chrystelle; Miele, Philippe

    2016-01-21

    Hexagonal boron nitride (h-BN) attracts considerable interest because its structure is similar to that of carbon graphite while it displays different properties which are of interest for environmental and green technologies. The polar nature of the B-N bond in sp(2)-bonded BN makes it a wide band gap insulator with different chemistry on its surface and particular physical and chemical properties such as a high thermal conductivity, a high temperature stability, a high resistance to corrosion and oxidation and a strong UV emission. It is chemically inert and nontoxic and has good environmental compatibility. h-BN also has enhanced physisorption properties due to the dipolar fields near its surface. Such properties are closely dependent on the processing method. Bottom-up approaches consist of transforming molecular precursors into non-oxide ceramics with retention of the structural units inherent to the precursor molecule. The purpose of the present review is to give an up-to-date overview on the most recent achievements in the preparation of h-BN from borazine-based molecular single-source precursors including borazine and 2,4,6-trichloroborazine through both vapor phase syntheses and methods in the liquid/solid state involving polymeric intermediates, called the Polymer-Derived Ceramics (PDCs) route. In particular, the effect of the chemistry, composition and architecture of the borazine-based precursors and derived polymers on the shaping ability as well as the properties of h-BN is particularly highlighted.

  6. Synthesis and Characterization of Chemically Etched Nanostructured Silicon

    KAUST Repository

    Mughal, Asad Jahangir

    2012-05-01

    Silicon is an essential element in today’s modern world. Nanostructured Si is a more recently studied variant, which has currently garnered much attention. When its spatial dimensions are confined below a certain limit, its optical properties change dramatically. It transforms from an indirect bandgap material that does not absorb or emit light efficiently into one which can emit visible light at room temperatures. Although much work has been conducted in understanding the properties of nanostructured Si, in particular porous Si surfaces, a clear understanding of the origin of photoluminescence has not yet been produced. Typical synthesis approaches used to produce nanostructured Si, in particular porous Si and nanocrystalline Si have involved complex preparations used at high temperatures, pressures, or currents. The purpose of this thesis is to develop an easier synthesis approach to produce nanostructured Si as well as arrive at a clearer understanding of the origin of photoluminescence in these systems. We used a simple chemical etching technique followed by sonication to produce nanostructured Si suspensions. The etching process involved producing pores on the surface of a Si substrate in a solution containing hydrofluoric acid and an oxidant. Nanocrystalline Si as well as nanoscale amorphous porous Si suspensions were successfully synthesized using this process. We probed into the phase, composition, and origin of photoluminescence in these materials, through the use of several characterization techniques. TEM and SEM were used to determine morphology and phase. FT-IR and XPS were employed to study chemical compositions, and steady state and time resolved optical spectroscopy techniques were applied to resolve their photoluminescent properties. Our work has revealed that the type of oxidant utilized during etching had a significant impact on the final product. When using nitric acid as the oxidant, we formed nanocrystalline Si suspensions composed of

  7. Fulleropyrrolidine end-capped molecular wires for molecular electronics--synthesis, spectroscopic, electrochemical, and theoretical characterization

    DEFF Research Database (Denmark)

    Sørensen, Jakob Kryger; Fock, Jeppe; Pedersen, Anders Holmen

    2011-01-01

    In continuation of previous studies showing promising metal-molecule contact properties a variety of C(60) end-capped "molecular wires" for molecular electronics were prepared by variants of the Prato 1,3-dipolar cycloaddition reaction. Either benzene or fluorene was chosen as the central wire...... state. However, the fluorescence of C(60) was quenched by charge transfer from the wire to C(60). Quantum chemical calculations predict and explain the collapse of coherent electronic transmission through one of the fulleropyrrolidine-terminated molecular wires......., and synthetic protocols for derivatives terminated with one or two fullero[c]pyrrolidine "electrode anchoring" groups were developed. An aryl-substituted aziridine could in some cases be employed directly as the azomethine ylide precursor for the Prato reaction without the need of having an electron...

  8. Size-controlled synthesis of transition metal nanoparticles through chemical and photo-chemical routes

    Science.gov (United States)

    Tangeysh, Behzad

    The central objective of this work is developing convenient general procedures for controlling the formation and stabilization of nanoscale transition metal particles. Contemporary interest in developing alternative synthetic approaches for producing nanoparticles arises in large part from expanding applications of the nanomaterials in areas such as catalysis, electronics and medicine. This research focuses on advancing the existing nanoparticle synthetic routes by using a new class of polymer colloid materials as a chemical approach, and the laser irradiation of metal salt solution as a photo-chemical method to attain size and shape selectivity. Controlled synthesis of small metal nanoparticles with sizes ranging from 1 to 5nm is still a continuing challenge in nanomaterial synthesis. This research utilizes a new class of polymer colloid materials as nano-reactors and protective agents for controlling the formation of small transition metal nanoparticles. The polymer colloid particles were formed from cross-linking of dinegatively charged metal precursors with partially protonated poly dimethylaminoethylmethacrylate (PDMAEMA). Incorporation of [PtCl6]2- species into the colloidal particles prior to the chemical reduction was effectively employed as a new strategy for synthesis of unusually small platinum nanoparticles with narrow size distributions (1.12 +/-0.25nm). To explore the generality of this approach, in a series of proof-of-concept studies, this method was successfully employed for the synthesis of small palladium (1.4 +/-0.2nm) and copper nanoparticles (1.5 +/-0.6nm). The polymer colloid materials developed in this research are pH responsive, and are designed to self-assemble and/or disassemble by varying the levels of protonation of the polymer chains. This unique feature was used to tune the size of palladium nanoparticles in a small range from 1nm to 5nm. The procedure presented in this work is a new convenient room temperature route for synthesis of

  9. Plant polyphenols: chemical properties, biological activities, and synthesis.

    Science.gov (United States)

    Quideau, Stéphane; Deffieux, Denis; Douat-Casassus, Céline; Pouységu, Laurent

    2011-01-17

    Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Mechanochemical synthesis of nanostructured chemical hydrides in hydrogen alloying mills

    International Nuclear Information System (INIS)

    Wronski, Z.; Varin, R.A.; Chiu, C.; Czujko, T.; Calka, A.

    2007-01-01

    Mechanical alloying of magnesium metal powders with hydrogen in specialized hydrogen ball mills can be used as a direct route for mechanochemical synthesis of emerging chemical hydrides and hydride mixtures for advanced solid-state hydrogen storage. In the 2Mg-Fe system, we have successfully synthesized the ternary complex hydride Mg 2 FeH 6 in a mixture with nanometric Fe particles. The mixture of complex magnesium-iron hydride and nano-iron released 3-4 wt.%H 2 in a thermally programmed desorption experiment at the range 285-295 o C. Milling of the Mg-2Al powder mixture revealed a strong competition between formation of the Al(Mg) solid solution and the β-MgH 2 hydride. The former decomposes upon longer milling as the Mg atoms react with hydrogen to form the hydride phase, and drive the Al out of the solid solution. The mixture of magnesium dihydride and nano-aluminum released 2.1 wt.%H 2 in the temperature range 329-340 o C in the differential scanning calorimetry experiment. The formation of MgH 2 was suppressed in the Mg-B system; instead, a hydrogenated amorphous phase (Mg,B)H x , was formed in a mixture with nanometric MgB 2 . Annealing of the hydrogen-stabilized amorphous mixture produced crystalline MgB 2

  11. Mechano-chemical synthesis of strontium britholites: Reaction mechanism

    International Nuclear Information System (INIS)

    Gmati, N.; Boughzala, K.; Bouzouita, K.; Abdellaoui, M.

    2011-01-01

    The britholites have gained a great interest thanks to their potential applications as matrices for the confinement of the byproducts in the nuclear industry such as minor actinides and long-lived fission products. However, the preparation of britholites requires high temperatures, above 1200 C. In this work, we strive to prepare these kinds of compounds by a mechano-chemical synthesis at room temperature from the starting materials SrF 2 , SrCO 3 , Sr 2 P 2 O 7 , La 2 O 3 and SiO 2 using a planetary ball mill. The obtained results showed that the prepared products were carbonated apatites and the corresponding powders contained some unreacted silica and lanthana. To obtain pure britholites, a heat-treatment at 1100 C was required. The mechanism involved in the different steps of the reaction is discussed in this paper. The obtained results suggest that the use of raw materials containing no carbonate is expected to directly lead to pure britholites by appropriate milling at room temperature. (authors)

  12. Molecular design, synthesis and physical properties of novel Cytisine-derivatives - Experimental and theoretical study

    Science.gov (United States)

    Ivanova, Bojidarka; Spiteller, Michael

    2013-02-01

    The paper presented a comprehensive theoretical and experimental study on the molecular drugs-design, synthesis, isolation, physical spectroscopic and mass spectrometric elucidation of novel functionalization derivatives of Cytisine (Cyt), using nucleosidic residues. Since these alkaloids have established biochemical profile, related the binding affinity of the nicotinic acetylcholine receptors (nAChRs), particularly α7 sub-type, the presented correlation between the molecular structure and properties allowed to evaluated the highlights of the biochemical hypothesises related the Schizophrenia. The anticancer activity of α7 subtype agonists and the crucial role of the nucleoside-based medications in the cancer therapy provided opportunity for further study on the biochemical relationship between Schizophrenia and few kinds of cancers, which has been hypothesized recently. The physical electronic absorptions (EAs), circular dichroic (CD) and Raman spectroscopic (RS) properties as well as mass spectrometric (MS) data, obtained using electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) methods under the positive single (MS) and tandem (MS/MS) modes of operation are discussed. Taking into account reports on a fatal intoxication of Cyt, the presented data would be of interest in the field of forensic chemistry, through development of highly selective and sensitive analytical protocols. Quantum chemical method is used to predict the physical properties of the isolated alkaloids, their affinity to the receptor loop and gas-phase stabilized species, observed mass spectrometrically.

  13. DEVELOPMENT OF ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    Energy Technology Data Exchange (ETDEWEB)

    Peter J. Tijrn

    2003-05-31

    This Final Report for Cooperative Agreement No. DE-FC22-95PC93052, the ''Development of Alternative Fuels and Chemicals from Synthesis Gas,'' was prepared by Air Products and Chemicals, Inc. (Air Products), and covers activities from 29 December 1994 through 31 July 2002. The overall objectives of this program were to investigate potential technologies for the conversion of synthesis gas (syngas), a mixture primarily of hydrogen (H{sub 2}) and carbon monoxide (CO), to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at the LaPorte, Texas Alternative Fuels Development Unit (AFDU). Laboratory work was performed by Air Products and a variety of subcontractors, and focused on the study of the kinetics of production of methanol and dimethyl ether (DME) from syngas, the production of DME using the Liquid Phase Dimethyl Ether (LPDME{trademark}) Process, the conversion of DME to fuels and chemicals, and the production of other higher value products from syngas. Four operating campaigns were performed at the AFDU during the performance period. Tests of the Liquid Phase Methanol (LPMEOH{trademark}) Process and the LPDME{trademark} Process were made to confirm results from the laboratory program and to allow for the study of the hydrodynamics of the slurry bubble column reactor (SBCR) at a significant engineering scale. Two campaigns demonstrated the conversion of syngas to hydrocarbon products via the slurry-phase Fischer-Tropsch (F-T) process. Other topics that were studied within this program include the economics of production of methyl tert-butyl ether (MTBE), the identification of trace components in coal-derived syngas and the means to economically remove these species, and the study of systems for separation of wax from catalyst in the F-T process. The work performed under this Cooperative Agreement has continued to promote the development of technologies that use clean syngas produced

  14. Chemical Synthesis of Proanthocyanidins in Vitro and Their Reactions in Aging Wines

    Directory of Open Access Journals (Sweden)

    Qiu-Hong Pan

    2008-12-01

    Full Text Available Proanthocyanidins are present in many fruits and plant products like grapes and wine, and contribute to their taste and health benefits. In the past decades of years, substantial progresses has been achieved in the identification of composition and structure of proanthocyanidins, but the debate concerning the existence of an enzymatic or nonenzymatic mechanism for proanthocyanidin condensation still goes on. Substantial attention has been paid to elucidating the potential mechanism of formation by means of biomimetic and chemical synthesis in vitro. The present paper aims at summarizing the research status on chemical synthesis of proanthocyanidins, including non-enzymatic synthesis of proanthocyanidin precursors, chemical synthesis of proanthocyanidins with direct condensation of flavanols and stereoselective synthesis of proanthocyanidins. Proanthocyanidin-involved reactions in aging wines are also reviewed such as direct and indirect reactions among proanthocyanidins, flavanols and anthocyanins. Topics for future research in this field are also put forward in this paper.

  15. Solid-phase synthesis of molecularly imprinted nanoparticles.

    Science.gov (United States)

    Canfarotta, Francesco; Poma, Alessandro; Guerreiro, Antonio; Piletsky, Sergey

    2016-03-01

    Molecularly imprinted polymers (MIPs) are synthetic materials, generally based on acrylic or methacrylic monomers, that are polymerized in the presence of a specific target molecule called the 'template' and capable of rebinding selectively to this target molecule. They have the potential to be low-cost and robust alternatives to biomolecules such as antibodies and receptors. When prepared by traditional synthetic methods (i.e., with free template in solution), their usefulness has been limited by high binding site heterogeneity, the presence of residual template and the fact that the production methods are complex and difficult to standardize. To overcome some of these limitations, we developed a method for the synthesis of MIP nanoparticles (nanoMIPs) using an innovative solid-phase approach, which relies on the covalent immobilization of the template molecules onto the surface of a solid support (glass beads). The obtained nanoMIPs are virtually free of template and demonstrate high affinity for the target molecule (e.g., melamine and trypsin in our published work). Because of an affinity separation step performed on the solid phase after polymerization, poor binders and unproductive polymer are removed, so the final product has more uniform binding characteristics. The overall protocol, starting from the immobilization of the template onto the solid phase and including the purification and characterization of the nanoparticles, takes up to 1 week.

  16. Direct chemical synthesis of MnO2 nanowhiskers on MXene surfaces for supercapacitor applications

    KAUST Repository

    Baby, Rakhi Raghavan; Ahmed, Bilal; Anjum, Dalaver H.; Alshareef, Husam N.

    2016-01-01

    Transition metal carbides (MXenes) are an emerging class of two dimensional (2D) materials with promising electrochemical energy storage performance. Herein, for the first time, by direct chemical synthesis, nanocrystalline ε-MnO2 whiskers were

  17. Utilization of molecular species of diglycerides in the synthesis of lecithin

    NARCIS (Netherlands)

    Mudd, J.B.; Golde, L.M.G. van; Deenen, L.L.M. van

    1969-01-01

    1. 1. The synthesis of lecithin by rat liver microsomes was measured in the presence of [14C]CDP-choline and three molecular species of diglycerides derived from rat liver lecithin containing four, two and one double bond. The rate of synthesis of lecithin was the same regardless of the fatty acid

  18. Synthesis of High-Molecular-Weight Multifunctional Glycerol Polyhydroxyurethanes PHUs

    Directory of Open Access Journals (Sweden)

    Bassam Nohra

    2016-09-01

    Full Text Available Glycerol carbonate acrylate is a 5-membered cyclic carbonate synthesized from glycerol that is used as a chemical coupling agent and has proven highly suitable for use in the synthesis of multifunctional polyhydroxyurethanes (PHUs. The multifunctionality of the structure of PHUs is determined by the density of the carbon-amine groups generated by the Aza-Michael reaction and that of the urethane groups and adjacent primary and secondary hydroxyl groups generated by aminolysis. Glycerol carbonate acrylate is polymerized with polyfunctional mono-, di-, tri, and tetra-amines, by type-AB polyaddition, either in bulk or in solution, through stepwise or one-pot reaction strategies in the absence of added catalysts. These approaches result in the generation of linear, interchain, and crosslinked structures, through the polyaddition of linear and branched amines to the ethylene and cyclic carbonate sites of glycerol carbonate acrylate. The resulting collection of organic molecules gives rise to polyethylene amino ester PHUs with a high molar mass, exceeding 20,000 g·mol−1, with uniform dispersity.

  19. Chemical protein synthesis: Inventing synthetic methods to decipher how proteins work.

    Science.gov (United States)

    Kent, Stephen

    2017-09-15

    Total chemical synthesis of proteins has been rendered practical by the chemical ligation principle: chemoselective condensation of unprotected peptide segments equipped with unique, mutually reactive functional groups, enabled by formation of a non-native replacement for the peptide bond. Ligation chemistries are briefly described, including native chemical ligation - thioester-mediated, amide-forming reaction at Xaa-Cys sites - and its extensions. Case studies from the author's own works are used to illustrate the utility and applications of chemical protein synthesis. Selected recent developments in the field are briefly discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Chemical structure and properties of low-molecular furin inhibitors

    Directory of Open Access Journals (Sweden)

    T. V. Osadchuk

    2016-12-01

    Full Text Available The review is devoted to the analysis of the relationship between a chemical structure and properties of low-molecular weight inhibitors of furin, the most studied proprotein convertase, which is involved in the development of some pathologies, such as oncologic diseases, viral and bacterial infections, etc. The latest data concerning the influence of peptides, pseudo-peptides, aromatic and heterocyclic compounds, some natural ones such as flavonoids, coumarins, and others on enzyme inactivation are considered. The power of furin inhibition is shown to rise with the increasing number of positively charged groups in the structure of these compounds. Peptidomimetics (Ki = 5-8 pM are shown to be the most effective furin inhibitors. The synthesized substances, however, have not been used in practical application yet. Nowadays it is very important to find more selective inhibitors, improve their stability, bioavailability and safety for the human organism.

  1. An Efficient, Green Chemical Synthesis of the Malaria Drug ...

    African Journals Online (AJOL)

    Purpose: To provide a robust, efficient synthesis of the malaria drug piperaquine for potential use in resource-poor settings. Methods: We used in-process analytical technologies (IPAT; HPLC) and a program of experiments to develop a synthesis of piperaquine that avoids the presence of a toxic impurity in the API and is ...

  2. Synthesis of one-dimensional metal-containing insulated molecular wire with versatile properties directed toward molecular electronics materials.

    Science.gov (United States)

    Masai, Hiroshi; Terao, Jun; Seki, Shu; Nakashima, Shigeto; Kiguchi, Manabu; Okoshi, Kento; Fujihara, Tetsuaki; Tsuji, Yasushi

    2014-02-05

    We report, herein, the design, synthesis, and properties of new materials directed toward molecular electronics. A transition metal-containing insulated molecular wire was synthesized through the coordination polymerization of a Ru(II) porphyrin with an insulated bridging ligand of well-defined structure. The wire displayed not only high linearity and rigidity, but also high intramolecular charge mobility. Owing to the unique properties of the coordination bond, the interconversion between the monomer and polymer states was realized under a carbon monoxide atmosphere or UV irradiation. The results demonstrated a high potential of the metal-containing insulated molecular wire for applications in molecular electronics.

  3. Molecular Design of Bioinspired Nanostructures for Biomedical Applications: Synthesis, Self-Assembly and Functional Properties

    Science.gov (United States)

    Xu, Hesheng Victor; Zheng, Xin Ting; Mok, Beverly Yin Leng; Ibrahim, Salwa Ali; Yu, Yong; Tan, Yen Nee

    2016-08-01

    Biomolecules are the nanoscale building blocks of cells, which play multifaceted roles in the critical biological processes such as biomineralization in a living organism. In these processes, the biological molecules such as protein and nucleic acids use their exclusive biorecognition properties enabled from their unique chemical composition, shape and function to initiate a cascade of cellular events. The exceptional features of these biomolecules, coupled with the recent advancement in nanotechnology, have led to the emergence of a new research field that focuses on the molecular design of bioinspired nanostructures that inherit the extraordinary function of natural biomaterials. These “bioinspired” nanostructures could be formulated by biomimetic approaches through either self-assembling of biomolecules or acting as a biomolecular template/precursor to direct the synthesis of nanocomposite. In either situation, the resulting nanomaterials exhibit phenomenal biocompatibility, superb aqueous solubility and excellent colloidal stability, branding them exceptionally desirable for both in vitro and in vivo biomedical applications. In this review, we will present the recent developments in the preparation of “bioinspired” nanostructures through biomimetic self-assembly and biotemplating synthesis, as well as highlight their functional properties and potential applications in biomedical diagnostics and therapeutic delivery. Lastly, we will conclude this topic with some personal perspective on the challenges and future outlooks of the “bioinspired” nanostructures for nanomedicine.

  4. A statistical view of protein chemical synthesis using NCL and extended methodologies.

    Science.gov (United States)

    Agouridas, Vangelis; El Mahdi, Ouafâa; Cargoët, Marine; Melnyk, Oleg

    2017-09-15

    Native chemical ligation and extended methodologies are the most popular chemoselective reactions for protein chemical synthesis. Their combination with desulfurization techniques can give access to small or challenging proteins that are exploited in a large variety of research areas. In this report, we have conducted a statistical review of their use for protein chemical synthesis in order to provide a flavor of the recent trends and identify the most popular chemical tools used by protein chemists. To this end, a protein chemical synthesis (PCS) database (http://pcs-db.fr) was created by collecting a set of relevant data from more than 450 publications covering the period 1994-2017. A preliminary account of what this database tells us is presented in this report. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Chemical point detection using differential fluorescence from molecularly imprinted polymers

    Science.gov (United States)

    Pestov, Dmitry; Anderson, John E.; Nelson, Jean; Tepper, Gary C.

    2004-12-01

    Fluorescence represents one of the most attractive approaches for chemical sensing due to the abundant light produced by most fluorophores, resulting in excellent detection sensitivity. However, the broad and overlapping emission spectra of target and background species have made it difficult to perform species identification in a field instrument because of the need to perform spectral decomposition and analysis. This paper describes a new chemical sensing strategy based on differential fluorescence measurements from molecularly imprinted polymers, which eliminates the need to perform any spectral analysis. Species identification is accomplished by measuring the differential light output from a pair of polymers-one imprinted to a target species and the other identical, but not imprinted. The imprinted polymer selectively concentrates the target molecule and controls the energy (wavelength) of the emitted fluorescence signal and the differential output eliminates common mode signals associated with non-specific background interference. Because no spectral analysis is required, the sensors can be made extremely small and require very little power. Preliminary performance parameters from a prototype sensor are presented and discussed.

  6. Synthesis and chemical recycling of high polymers using C1 compounds; C1 kagobutsu ni yoru kobunshi no chemical recycle

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, T. [National Institute of Materials and Chemical Research, Tsukuba (Japan)

    1997-09-01

    The paper outlined a study of the synthesis of high polymers using C1 compounds which are continuously usable chemical materials and the related compounds such as the derivatives, and also the chemical recycle. In the case of waste plastics mixed in urban refuse, effective is the chemical recycle where C1 compounds obtained by gasifying the mixed waste are used as high polymer material. For the synthesis and recycle of high polymers using C1 compounds, there are three routes: Route A (recycle via high polymer materials), Route B (recycle via C1 compounds and high polymer materials), and Route C including global-scale carbon recycle (recycle via carbon dioxide from biodegradable plastics using microorganism). Among high polymers, those that can be synthesized from C1 compounds, for example, polymethylene, polyacetal and polyketone can be chemically recycled by Route B. 30 refs., 2 figs., 1 tab.

  7. Synthesis, chemical and biological quality control of radioiodinated peptides

    International Nuclear Information System (INIS)

    Rafii, H.; Khalaj, A.; Beiki, D.; Motameidi, F.; Maloobi, M.; Karimian-dehghan, M.; Keshavarrzi, F.

    2002-01-01

    Iodinated compounds with I-131, 125 and 123 have been widely used for biochemical function studies. In conjunction with SPECT, [I-123] labelled proteins have various diagnostic and therapeutic applications in nuclear medicine. Preparation of some radioiodinated peptides with tyrosine and/or lysine groups on their main chain molecules can be carried out with both direct and indirect methods, but lack of these groups in molecule cause the molecule dose not lend itself for direct radioiodination. In this study, human IgG and Formyl-Methyl-Leucyl-Phenylalanine, FMLF, have been chosen as a model compounds for direct and indirect radioiodination respectively. Here, we will describe the labelling procedure of [I-125] IgG using chloramine-T as a suitable oxidant agent and [I-125 and I-131] FMLF by indirect method using ATE/SIB as a prosthetic group in multi-step reactions. The obtained results for chemical quality control of intermediate radioiodinated SIB by HPLC and two labelled IgG and FMLF will be also discussed. Biological results, biodistribution studies and SPECT scans on mice per-injected labelled FMLF show a low uptake of thyroid but a high at urine and bladder, perhaps because of low molecular weight of FMLF. In this case, it seems to be better to separate the reaction mixture of labelled FMLF by BPLC than Sephadex-G50 gel filtration. (Author)

  8. Synthesis of New Vinyl Monomers for Chemical Agent Sensing Applications

    National Research Council Canada - National Science Library

    Hogen-Esch, Thieo

    2001-01-01

    The synthesis of styrene momomer p-vinylbenzoylacetophenone (monomer i) has been carried by the acetylation of 2- chloroethylbenzene and base elimination of the resulting 4-acetyl-2-chloroethylbenzene to give 4-acetylstyrene...

  9. Sustainable Applications of Nano-Catalysts and Alternative Methods in the Greener Synthesis and Transformations of Chemical

    Science.gov (United States)

    The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a var...

  10. Chemically functionalized gold nanoparticles: Synthesis, characterization, and applications

    Science.gov (United States)

    Daniel, Weston Lewis

    This thesis focuses on the development and application of gold nanoparticle based detection systems and biomimetic structures. Each class of modified nanoparticle has properties that are defined by its chemical moieties that interface with solution and the gold nanoparticle core. In Chapter 2, a comparison of the biomolecular composition and binding properties of various preparations of antibody oligonucleotide gold nanoparticle conjugates is presented. These constructs differed significantly in terms of their structure and binding properties. Chapter 3 reports the use of electroless gold deposition as a light scattering signal enhancer in a multiplexed, microarray-based scanometric immunoassay using the gold nanoparticle probes evaluated in Chapter 2. The use of gold development results in greater signal enhancement than the typical silver development, and multiple rounds of metal development were found to increase the resulting signal compared to one development. Chapter 4 describes an amplified scanometric detection method for human telomerase activity. Gold nanoparticles functionalized with specific oligonucleotide sequences can efficiently capture telomerase enzymes and subsequently be elongated. Both the elongated and unmodified oligonucleotide sequences are simultaneously measured. At low telomerase concentrations, elongated strands cannot be detected, but the unmodified sequences, which come from the same probe particles, can be detected because their concentration is higher, providing a novel form of amplification. Chapter 5 reports the development of a novel colorimetric nitrite and nitrate ion assay based upon gold nanoparticle probes functionalized with Griess reaction reagents. This assay takes advantage of the distance-dependent plasmonic properties of the gold nanoparticles and the ability of nitrite ion to facilitate the cross coupling of novel nanoparticle probes. The assay works on the concept of a kinetic end point and can be triggered at the EPA

  11. Cyclopenta[b]naphthalene cyanoacrylate dyes: synthesis and evaluation as fluorescent molecular rotors.

    Science.gov (United States)

    Kocsis, Laura S; Elbel, Kristyna M; Hardigree, Billie A; Brummond, Kay M; Haidekker, Mark A; Theodorakis, Emmanuel A

    2015-03-14

    We describe the design, synthesis and fluorescent profile of a family of environment-sensitive dyes in which a dimethylamino (donor) group is conjugated to a cyanoacrylate (acceptor) unit via a cyclopenta[b]naphthalene ring system. This assembly satisfies the typical D-π-A motif of a fluorescent molecular rotor and exhibits solvatochromic and viscosity-sensitive fluorescence emission. The central naphthalene ring system of these dyes was synthesized via a novel intramolecular dehydrogenative dehydro-Diels-Alder (IDDDA) reaction that permits incorporation of the donor and acceptor groups in variable positions around the aromatic core. A bathochromic shift of excitation and emission peaks was observed with increasing solvent polarity but the dyes exhibited a complex emission pattern with a second red emission band when dissolved in nonpolar solvents. Consistent with other known molecular rotors, the emission intensity increased with increasing viscosity. Interestingly, closer spatial proximity between the donor and the acceptor groups led to decreased viscosity sensitivity combined with an increased quantum yield. This observation indicates that structural hindrance of intramolecular rotation dominates when the donor and acceptor groups are in close proximity. The examined compounds give insight into how excited state intramolecular rotation can be influenced by both the solvent and the chemical structure.

  12. Synthesis and Characterization of Magnesium Substituted Aluminophosphate Molecular Sieves with AEL Structure

    Institute of Scientific and Technical Information of China (English)

    Benjing Xu; Ling Qian; Xinmei Liu; Chunmin Song; Zifeng Yan

    2004-01-01

    MAPO-11 molecular sieves were synthesized by hydrothermal methods. The influence of precursor of magnesium, Mg/Al ratio, synthesis temperature, synthesis time and the type of template on the formation and properties of MAPO-11 molecular sieves was examined. The samples were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric/differential thermogravimetric analysis (TG-DGA), etc. The results show that the shape and size of crystal were influenced by the precursor of Mg, the Mg/Al ratio and the type of template, and the TG-DGA analysis shows that MAPO-11 molecular sieves as-synthesized have poor thermal stability.

  13. Chemical and thermal modulation of molecular motor activities

    Science.gov (United States)

    Hong, Weili

    Molecular motors of kinesin and dynein families are responsible for various intracellular activities, from long distance movement of organelles, vesicles, protein complexes, and mRNAs to powering mitotic processes. They can take nanometer steps using chemical energy from the hydrolysis of ATP (adenosine triphosphate), and their dysfunction is involved in many neurodegenerative diseases that require long distance transport of cargos. Here I report on the study of the properties of molecular motors at a single-molecule level using optical trappings. I first studied the inhibition properties of kinesin motors by marine natural compound adociasulfates. I showed that adociasulfates compete with microtubules for binding to kinesins and thus inhibit kinesins' activity. Although adociasulfates are a strong inhibitor for all kinesin members, they show a much higher inhibition effect for conventional kinesins than for mitotic kinesins. Thus adociasulfates can be used to specifically inhibit conventional kinesins. By comparing the inhibition of kinesins by two structurally similar adociasulfates, one can see that the negatively charged sulfate residue of adociasulfates can be replaced by other negative residues and thus make it possible for adociasulfate-derived compounds to be more cell permeable. Kinesins and dyneins move cargos towards opposite directions along a microtubule. Cargos with both kinesins and dyneins attached often move bidirectionally due to undergoing a tug-of-war between the oppositely moving kinesin and dynein motors. Here I studied the effect of temperature on microtubule-based kinesin and dynein motor transport. While kinesins' and dyneins' velocities are closely matched above 15 °C, below this temperature the dyneins' velocity decreases much faster than the kinesins'. The kinesins' and dyneins' forces do not measurably change with temperature. The results suggest that temperature has significant effects on bidirectional transport and can be used to

  14. Understanding Molecular Interactions within Chemically Selective Layered Polymer Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Gary J. Blanchard

    2009-06-30

    This work focuses on two broad issues. These are (1) the molecular origin of the chemical selectivity achieved with ultrathin polymer multilayers, and (2) how the viscoelastic properties of the polymer layers are affected by exposure to solvent and analytes. These issues are inter-related, and to understand them we need to design experiments that probe both the energetic and kinetic aspects of interfacial adsorption processes. This project focuses on controling the chemical structure, thickness, morphology and sequential ordering of polymer layers bound to interfaces using maleimide-vinyl ether and closely related alternating copolymerization chemistry and efficient covalent cross-linking reactions that allow for layer-by-layer polymer deposition. This chemistry has been developed during the funding cycle of this Grant. We have measure the equilibrium constants for interactions between specific layers within the polymer interfaces and size-controlled, surface-functionalized gold nanoparticles. The ability to control both size and functionality of gold nanoparticle model analytes allows us to evaluate the average “pore size” that characterizes our polymer films. We have measured the “bulk” viscosity and shear modulus of the ultrathin polymer films as a function of solvent overlayer identity using quartz crystal microbalance complex impedance measurements. We have measured microscopic viscosity at specific locations within the layered polymer interfaces with time-resolved fluorescence lifetime and depolarization techniques. We combine polymer, cross-linking and nanoparticle synthetic expertise with a host of characterization techniques, including QCM gravimetry and complex impedance analysis, steady state and time-resolved spectroscopies.

  15. CHEMICAL SYNTHESIS USING 'GREENER' ALTERNATIVE REACTION CONDITIONS AND MEDIA

    Science.gov (United States)

    The chemical research during the last decade has witnessed a paradigm shift towards "environmentally-friendly chemistry" more popularly known as "green chemistry" due to the increasing environmental concerns and legislative requirements to curb the release of chemical waste into ...

  16. Molecular Spectrum Capture by Tuning the Chemical Potential of Graphene

    Directory of Open Access Journals (Sweden)

    Yue Cheng

    2016-05-01

    Full Text Available Due to its adjustable electronic properties and effective excitation of surface plasmons in the infrared and terahertz frequency range, research on graphene has attracted a great deal of attention. Here, we demonstrate that plasmon modes in graphene-coated dielectric nanowire (GNW waveguides can be excited by a monolayer graphene ribbon. What is more the transverse resonant frequency spectrum of the GNW can be flexibly tuned by adjusting the chemical potential of graphene, and amplitude of the resonance peak varies linearly with the imaginary part of the analyte permittivity. As a consequence, the GNW works as a probe for capturing the molecular spectrum. Broadband sensing of toluene, ethanol and sulfurous anhydride thin layers is demonstrated by calculating the changes in spectral intensity of the propagating mode and the results show that the intensity spectra correspond exactly to the infrared spectra of these molecules. This may open an effective avenue to design sensors for detecting nanometric-size molecules in the terahertz and infrared regimes.

  17. In Situ Correlated Molecular Imaging of Chemically Communicating Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    Bohn, Paul W. [Univ. of Notre Dame, IN (United States); Shrout, J. D. [Univ. of Notre Dame, IN (United States); Sweedler, J. V. [Univ. of Illinois, Urbana-Champaign, IL (United States); Farrand, S. [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2016-01-25

    This document constitutes the final technical report for DE-SC0006642, In Situ Correlated Molecular Imaging of Chemically Communicating Microbial Communities, a project carried out collaboratively by investigators at Notre Dame and UIUC. The work carried out under DOE support in this project produced advances in two areas: development of new highly sophisticated correlated imaging approaches and the application of these new tools to the growth and differentiation of microbial communities under a variety of environmental conditions. A significant effort involved the creation of technical enhancements and sampling approaches to allow us to advance heterocorrelated mass spectrometry imaging (MSI) and correlated Raman microscopy (CRM) from bacterial cultures and biofilms. We then exploited these measurement advances in heterocorrelated MS/CRM imaging to determine relationship of signaling molecules and excreted signaling molecules produced by P. aeruginosa to conditions relevant to the rhizosphere. In particular, we: (1) developed a laboratory testbed mimic for the rhizosphere to enable microbial growth on slides under controlled conditions; (2) integrated specific measurements of (a) rhamnolipids, (b) quinolone/quinolones, and (c) phenazines specific to P. aeruginosa; and (3) utilized the imaging tools to probe how messenger secretion, quorum sensing and swarming behavior are correlated with behavior.

  18. Machine learning of molecular electronic properties in chemical compound space

    Science.gov (United States)

    Montavon, Grégoire; Rupp, Matthias; Gobre, Vivekanand; Vazquez-Mayagoitia, Alvaro; Hansen, Katja; Tkatchenko, Alexandre; Müller, Klaus-Robert; Anatole von Lilienfeld, O.

    2013-09-01

    The combination of modern scientific computing with electronic structure theory can lead to an unprecedented amount of data amenable to intelligent data analysis for the identification of meaningful, novel and predictive structure-property relationships. Such relationships enable high-throughput screening for relevant properties in an exponentially growing pool of virtual compounds that are synthetically accessible. Here, we present a machine learning model, trained on a database of ab initio calculation results for thousands of organic molecules, that simultaneously predicts multiple electronic ground- and excited-state properties. The properties include atomization energy, polarizability, frontier orbital eigenvalues, ionization potential, electron affinity and excitation energies. The machine learning model is based on a deep multi-task artificial neural network, exploiting the underlying correlations between various molecular properties. The input is identical to ab initio methods, i.e. nuclear charges and Cartesian coordinates of all atoms. For small organic molecules, the accuracy of such a ‘quantum machine’ is similar, and sometimes superior, to modern quantum-chemical methods—at negligible computational cost.

  19. Machine learning of molecular electronic properties in chemical compound space

    International Nuclear Information System (INIS)

    Montavon, Grégoire; Müller, Klaus-Robert; Rupp, Matthias; Gobre, Vivekanand; Hansen, Katja; Tkatchenko, Alexandre; Vazquez-Mayagoitia, Alvaro; Anatole von Lilienfeld, O

    2013-01-01

    The combination of modern scientific computing with electronic structure theory can lead to an unprecedented amount of data amenable to intelligent data analysis for the identification of meaningful, novel and predictive structure–property relationships. Such relationships enable high-throughput screening for relevant properties in an exponentially growing pool of virtual compounds that are synthetically accessible. Here, we present a machine learning model, trained on a database of ab initio calculation results for thousands of organic molecules, that simultaneously predicts multiple electronic ground- and excited-state properties. The properties include atomization energy, polarizability, frontier orbital eigenvalues, ionization potential, electron affinity and excitation energies. The machine learning model is based on a deep multi-task artificial neural network, exploiting the underlying correlations between various molecular properties. The input is identical to ab initio methods, i.e. nuclear charges and Cartesian coordinates of all atoms. For small organic molecules, the accuracy of such a ‘quantum machine’ is similar, and sometimes superior, to modern quantum-chemical methods—at negligible computational cost. (paper)

  20. Molecular Consortia—Various Structural and Synthetic Concepts for More Effective Therapeutics Synthesis

    Directory of Open Access Journals (Sweden)

    Anna Pawełczyk

    2018-04-01

    Full Text Available The design and discovery of novel drug candidates are the initial and most probably the crucial steps in the drug development process. One of the tasks of medicinal chemistry is to produce new molecules that have a desired biological effect. However, even today the search for new pharmaceuticals is a very complicated process that is hard to rationalize. Literature provides many scientific reports on future prospects of design of potentially useful drugs. Many trends have been proposed for the design of new drugs containing different structures (dimers, heterodimers, heteromers, adducts, associates, complexes, biooligomers, dendrimers, dual-, bivalent-, multifunction drugs and codrugs, identical or non-identical twin drugs, mixed or combo drugs, supramolecular particles and various nanoindividuals. Recently much attention has been paid to different strategies of molecular hybridization. In this paper, various molecular combinations were described e.g., drug–drug or drug-non-drug combinations which are expressed in a schematic multi-factor form called a molecular matrix, consisting of four factors: association mode, connection method, and the number of elements and linkers. One of the most popular trends is to create small–small molecule combinations such as different hybrids, codrugs, drug–drug conjugates (DDCs and small-large molecule combinations such as antibody-drug conjugates (ADCs, polymer-drug conjugates (PDCs or different prodrugs and macromolecular therapeutics. A review of the structural possibilities of active framework combinations indicates that a wide range of potentially effective novel-type compounds can be formed. What is particularly important is that new therapeutics can be obtained in fast, efficient, and selective methods using current trends in chemical synthesis and the design of drugs such as the “Lego” concept or rational green approach.

  1. Expanding the pleuromutilin class of antibiotics by de novo chemical synthesis

    Science.gov (United States)

    Lotesta, Stephen D.; Liu, Junjia; Yates, Emma V.; Krieger, Inna; Sacchettini, James C.; Freundlich, Joel S.; Sorensen, Erik J.

    2011-01-01

    New pleuromutilin-like compounds were synthesized in approximately 11 steps from 3-allylcyclopent-2-enone by a strategy featuring sequential carbonyl addition reactions. Several analogs possessing the C14 tiamulin ester side chain displayed activity in a Mycobacterium tuberculosis mc27000 assay. The results described herein provide a basis for further efforts to expand the structural and stereochemical diversity of the pleuromutilin class of bacterial protein synthesis inhibitors through advances in chemical synthesis. PMID:21874155

  2. Synthesis and Characterization of Block Copolymers with Unique Chemical Functionalities and Entropically-Hindering Moieties

    Science.gov (United States)

    2017-08-14

    methanol as a function of chemistry , morphology and hydration levels. Accomplishments: This section is included in the "upload" section. Training...Copolymer Blend Membranes.” In Press, Polymer Engineering and Science, DOI: 10.1002 /pen.24508, 2017. 5. M. Pérez-Pérez and D. Suleiman. “Synthesis and...Synthesis and Characterization of Sulfonated Amine Block Copolymers for Energy Efficient Applications". Chemical Engineering Symposium, University of

  3. Synthesis, quantum chemical computations and x-ray ...

    African Journals Online (AJOL)

    Benyza N

    2017-05-01

    May 1, 2017 ... manganese (+II) co-ordination with pyridine-2,6-dicarboxamide oxime. We report here the synthesis, the single crystal X-ray structure of the complex and the Optimization of the structure using ... Absorption coefficient (mm. -1. ).

  4. Automated synthesis with HPLC purification of 18F-FMISO as specific molecular imaging probe of tumor hypoxia

    International Nuclear Information System (INIS)

    Wang Mingwei; Zhang Yingjian; Zhang Yongping

    2012-01-01

    An improved automated synthesis of 1-H-1-(3-[ 18 F] fluoro-2-hydroxypropyl)-2-nitro-imidazole ( 18 F-FMISO), a specific molecular imaging probe of tumor hypoxia, was developed using an upgraded Explora GN module integrated with Explora LC for HPLC purification in this study. The radiochemical synthesis of 18 F-FMISO was started with precursor 1-( 2'-nitro-1'-imidazolyl)-2-O-tetrahydropyranyl-3-O-tosyl-propanediol (NITTP) and included nucleophilic [ 18 F] radio-fluorination at 120℃ for 5 min and hydrolysis at 130℃ for 8 min. The automated synthesis of 18 F-FMISO, presenting fast, reliable and multi-run features, could be completed with the total synthesis time of less than 65 min and radiochemical yield of 25%∼35% (without decay correction). The quality control of 18 F-FMISO was identical with the radiopharmaceutical requirements, especially the radiochemical purity of greater than 99% and high chemical purity and specific activity own to HPLC purification. (authors)

  5. Approaches for introducing high molecular diversity in scaffolds: fast parallel synthesis of highly substituted 1H-quinolin-4-one libraries.

    Science.gov (United States)

    Kuznetsov, Vladimir; Gorohovsky, Sofia; Levy, Amalia; Meir, Simcha; Shkoulev, Vladimir; Menashe, Naim; Greenwald, Moshe; Aizikovich, Alexander; Ofer, Dror; Byk, Gerardo; Gellerman, Garry

    2004-01-01

    We have developed a two steps strategy for the parallel synthesis of highly diversified quinolin-ones. In the first step we have combined and improved different synthetic methods for generating quinolin-4-ones bearing four different substitutions at specific positions using round bottomed flasks. The synthesis was assessed for a large number of substituted quinolin-4-ones. In the second step, the improved method was adapted to a parallel array synthesis using a 12 positions carrousel as demonstrated for the synthesis of 42-variable quinolin-4-ones. The first combinatorial library set 14(a-x) was obtained with a chemical purity of more than 95% without purification, the second library set 15(a-r), which included two synthetic steps, needed combinatorial purification using an innovative parallel purifier. The proposed approach contributes to a more extensive diversification of molecular scaffolds in general and provides access to highly substituted quinolinones in particular.

  6. Direct synthesis of nanocrystalline oxide powders by wet-chemical techniques

    Directory of Open Access Journals (Sweden)

    Vladimir V. Srdić

    2010-09-01

    Full Text Available In a recent period there is a great need for increasing the knowledge of tailoring the innovative procedures for the synthesis of electroceramic nanopowders and materials with improved quality for specific application. In order to produce electroceramics with desirable microstructure and properties, synthesis of stoichiometric, ultra-fine and agglomerate free powders with narrow size distributions is one of the most important steps. Within this scope, in the present paper we summarize our recent results on direct synthesis of some important perovskites and ferrites nanopowders by wet-chemical techniques.

  7. Synthesis of Heteroaromatic Compounds by Oxidative Aromatization Using an Activated Carbon/Molecular Oxygen System

    Directory of Open Access Journals (Sweden)

    Masahiko Hayashi

    2009-08-01

    Full Text Available A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. In the final section, we will disclose the efficient synthesis of substituted 9,10-anthracenes via oxidative aromatization.

  8. Optimisation of the synthesis of vancomycin-selective molecularly imprinted polymer nanoparticles using automatic photoreactor

    OpenAIRE

    Muzyka, Kateryna; Karim, Khalku; Guerreiro, Antonio; Poma, Alessandro; Piletsky, Sergey

    2014-01-01

    A novel optimized protocol for solid-state synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) with specificity for antibiotic vancomycin is described. The experimental objective was optimization of the synthesis parameters (factors) affecting the yield of obtained nanoparticles which have been synthesized using the first prototype of an automated solid-phase synthesizer. Applications of experimental design (or design of experiments) in optimization of nanoMIP yield were carri...

  9. A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection

    Science.gov (United States)

    2015-09-01

    ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for...ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for Chemical...TITLE AND SUBTITLE A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection 5a. CONTRACT NUMBER 5b. GRANT NUMBER

  10. Molecular MRI using exogenous enzymatic sensors and endogenous chemical exchange contrast

    OpenAIRE

    Taylor, Alexander John

    2016-01-01

    Molecular magnetic resonance imaging (MRI) methods have the potential to provide detailed information regarding cellular and molecular processes at small scales within the human body. Nuclear signals from chemical samples can be probed using specialised MRI techniques, to highlight molecular contrast from particular enzymes or metabolites. The aim of the work described in this thesis is to investigate both exogenous and endogenous contrast mechanisms using fluorine MRI and chemical exchange s...

  11. A review of theoretical study of graphene chemical vapor deposition synthesis on metals: nucleation, growth, and the role of hydrogen and oxygen

    Science.gov (United States)

    Rezwan Habib, Mohammad; Liang, Tao; Yu, Xuegong; Pi, Xiaodong; Liu, Yingchun; Xu, Mingsheng

    2018-03-01

    Graphene has attracted intense research interest due to its extraordinary properties and great application potential. Various methods have been proposed for the synthesis of graphene, among which chemical vapor deposition has drawn a great deal of attention for synthesizing large-area and high-quality graphene. Theoretical understanding of the synthesis mechanism is crucial for optimizing the experimental design for desired graphene production. In this review, we discuss the three fundamental steps of graphene synthesis in details, i.e. (1) decomposition of carbon feedstocks and formation of various active carbon species, (2) nucleation, and (3) attachment and extension. We provide a complete scenario of graphene synthesis on metal surfaces at atomistic level by means of density functional theory, molecular dynamics (MD), Monte Carlo (MC) and their combination and interface with other simulation methods such as quantum mechanical molecular dynamics, density functional tight binding molecular dynamics, and combination of MD and MC. We also address the latest investigation of the influences of the hydrogen and oxygen on the synthesis and the quality of the synthesized graphene.

  12. Quantum chemical approaches: semiempirical molecular orbital and hybrid quantum mechanical/molecular mechanical techniques.

    Science.gov (United States)

    Bryce, Richard A; Hillier, Ian H

    2014-01-01

    The use of computational quantum chemical methods to aid drug discovery is surveyed. An overview of the various computational models spanning ab initio, density function theory, semiempirical molecular orbital (MO), and hybrid quantum mechanical (QM)/molecular mechanical (MM) methods is given and their strengths and weaknesses are highlighted, focussing on the challenge of obtaining the accuracy essential for them to make a meaningful contribution to drug discovery. Particular attention is given to hybrid QM/MM and semiempirical MO methods which have the potential to yield the necessary accurate predictions of macromolecular structure and reactivity. These methods are shown to have advanced the study of many aspects of substrate-ligand interactions relevant to drug discovery. Thus, the successful parametrization of semiempirical MO methods and QM/MM methods can be used to model noncovalent substrate-protein interactions, and to lead to improved scoring functions. QM/MM methods can be used in crystal structure refinement and are particularly valuable for modelling covalent protein-ligand interactions and can thus aid the design of transition state analogues. An extensive collection of examples from the areas of metalloenzyme structure, enzyme inhibition, and ligand binding affinities and scoring functions are used to illustrate the power of these techniques.

  13. “Miswak” Based Green Synthesis of Silver Nanoparticles: Evaluation and Comparison of Their Microbicidal Activities with the Chemical Synthesis

    Directory of Open Access Journals (Sweden)

    Mohammed Rafi Shaik

    2016-11-01

    Full Text Available Microbicidal potential of silver nanoparticles (Ag-NPs can be drastically improved by improving their solubility or wettability in the aqueous medium. In the present study, we report the synthesis of both green and chemical synthesis of Ag-NPs, and evaluate the effect of the dispersion qualities of as-prepared Ag-NPs from both methods on their antimicrobial activities. The green synthesis of Ag-NPs is carried out by using an aqueous solution of readily available Salvadora persica L. root extract (RE as a bioreductant. The formation of highly crystalline Ag-NPs was established by various analytical and microscopic techniques. The rich phenolic contents of S. persica L. RE (Miswak not only promoted the reduction and formation of NPs but they also facilitated the stabilization of the Ag-NPs, which was established by Fourier transform infrared spectroscopy (FT-IR analysis. Furthermore, the influence of the volume of the RE on the size and the dispersion qualities of the NPs was also evaluated. It was revealed that with increasing the volume of RE the size of the NPs was deteriorated, whereas at lower concentrations of RE smaller size and less aggregated NPs were obtained. During this study, the antimicrobial activities of both chemically and green synthesized Ag-NPs, along with the aqueous RE of S. persica L., were evaluated against various microorganisms. It was observed that the green synthesized Ag-NPs exhibit comparable or slightly higher antibacterial activities than the chemically obtained Ag-NPs.

  14. Molecular catalysis and high-volume organic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Khidekel, M L; Vasserberg, V E

    1977-01-01

    The field of catalysis is very wide. The properties of catalysts are briefly reviewed and compared with the properties of enzymes. Various uses of enxymes in industry (sugar from corn, cellulose breakdown, etc.) are pointed out. The types of homogeneous and heterogeneous catalysts for use in organic synthesis are discussed. 48 refs. (SJR)

  15. Synthesis of molecular imprinted beta cyclodextrins oligomers in water

    DEFF Research Database (Denmark)

    Yu, Donghong; Nielsen, Anne Louise; Bach, Lone

    2003-01-01

    compounds in aqueous solution and, therefore, molecular imprinting of cyclodextrins polymers in aqueous solution is of great interest. In this paper, molecular imprinting of beta cyclodextrins has been performed in water by use of diiodobenzene as template and epichlorohydrin as a crosslinker. Inclusion...

  16. Synthesis of chiral polyaniline films via chemical vapor phase polymerization

    DEFF Research Database (Denmark)

    Chen, J.; Winther-Jensen, B.; Pornputtkul, Y.

    2006-01-01

    Electrically and optically active polyaniline films doped with (1)-(-)-10- camphorsulfonic acid were successfully deposited on nonconductive substrates via chemical vapor phase polymerization. The above polyaniline/ R- camphorsulfonate films were characterized by electrochemical and physical...

  17. Chemical equilibrium of glycerol carbonate synthesis from glycerol

    International Nuclear Information System (INIS)

    Li Jiabo; Wang Tao

    2011-01-01

    Research highlights: → Transesterification of glycerol with cyclic carbonates or alkyl carbonates is thermodynamically favourable for the preparation of glycerol carbonate from glycerol. → The reaction of glycerol and carbon dioxide is thermodynamically limited. → High temperature and low pressure is favourable to the reaction of glycerol and urea. → Increasing temperature can increase the chemical equilibrium constant for the reaction of glycerol and dimethyl carbonate. → For the reaction of glycerol and ethylene carbonate, increasing temperature can decrease the chemical equilibrium constant. - Abstract: In this paper, the chemical equilibrium for the glycerol carbonate preparation from glycerol was investigated. The chemical equilibrium constants were calculated for the reactions to produce glycerol carbonate from glycerol. The theoretical calculation was compared with the experimental results for the transesterification of glycerol with dimethyl carbonate. Transesterification of glycerol with cyclic carbonates or alkyl carbonates is thermodynamically favourable for producing glycerol carbonate from glycerol according to the equilibrium constant. Increasing temperature can increase the chemical equilibrium constant for the reaction of glycerol with dimethyl carbonate. For the reaction of glycerol with ethylene carbonate, increasing temperature can decrease the chemical equilibrium constant. The reaction of glycerol with carbon dioxide is thermodynamically limited. High temperature and low pressure are favourable to the reaction of glycerol and urea.

  18. Synthesis, chemical and biological properties of the new mono- and bis-derivatives of imidazoles

    Directory of Open Access Journals (Sweden)

    E. V. Welchinska

    2014-12-01

    Full Text Available The aim of research. The problem of finding effective antitumour medical preparation with low toxicity is an important issue of medical and pharmaceutical chemistry. Knowledge of cancer cell features and its metabolism enables to predict the direction of chemical and biological research, to conduct a targeted synthesis of potential drugs, and to assess their applicability in oncological practice as antitumor agents. The purpose of work is to explain preformed heterocycles as purines, its synthesis and investigation of chemical and biological properties. After construction of the potential active structures we proposed the new method of original derivatives synthesis which are received on the base of imidazole, from one side, and fluorocontaining common anesthetic halothane (2-bromo-1,1,1-trifluoro-2-chloroethane from other side. Molecular complex of more perspective biologically active bis-imidazole with antitumour bacterial lectine has been received. With the purpose to synthesize potential antitumour compounds on the base of halothane and imidazole, new convenient methods for the preparation of original heterocyclic derivatives of imidazole have been described. The structure and composition of synthesized compound has been confirmed by the methods of elemental analysis, IR- and NMRІН-spectra. Materials and methods. The majority of the absolute organic solvents (benzene, dimethylformamide, ethyl ester employed in the present studies were distilled before their use. Organic solvents were dried over anhydrous magnesium sulfate or metallic sodium. Gas-liquid chromatography was carried out by Perkin Elmer chromatograph with UV-detector ("Perkin", Germany. IR spectra were recorded in a UR-20 spectrometer ("Charles Ceise Hena", Germany. The 1HNMR spectra were recorded in DMSO-d6 on a 200 MHz BrakerWP-200 ("Braker", Switzerland or Varian T-60 spectrometer ("Varian", USA. Investigation of critical toxicity of new compounds was carried out at

  19. Phosphorus-containing cyclodextrins. Characteristics of the synthesis and chemical behaviour

    International Nuclear Information System (INIS)

    Grachev, M K

    2013-01-01

    Published data on the preparation of phosphorus-containing cyclodextrins are summarized. It is demonstrated that some significant features of their synthesis and chemical behaviour are caused by specific supramolecular interactions involving the inner chiral cavity of cyclodextrins capable of incorporating various guests, which often leads to alteration of customary routes of chemical transformations. The possibilities of practical applications of phosphorus-containing cyclodextrins are briefly analyzed. The bibliography includes 89 references

  20. Applications of Process Synthesis: Moving from Conventional Chemical Processes towards Biorefinery Processes

    DEFF Research Database (Denmark)

    Yuan, Zhihong; Chen, Bingzhen; Gani, Rafiqul

    2013-01-01

    Concerns about diminishing petroleum reserves, enhanced worldwide demand for fuels and fluctuations in the global oil market, together with climate change and national security have promoted many initiatives for exploring alternative, non-petroleum based processes. Among these initiatives......, biorefinery processes for converting biomass-derived carbohydrates into transportation fuels and chemicals are now gaining more and more attention from both academia and industry. Process synthesis, which has played a vital role for the development, design and operation of (petro) chemical processes, can...

  1. Synthesis and molecular docking of pyrimidine incorporated novel ...

    Indian Academy of Sciences (India)

    APOORVA MISRA

    2018-03-09

    Mar 9, 2018 ... aDepartment of Chemistry, Banasthali Vidyapith, Banasthali, Rajasthan 304 022, India ... serotonin 5-HT6 receptor antagonist,22 hepatitis-A virus ..... Molecular docking structure and ligand protein binding sites of MTX- (a) ...

  2. Synthesis of homochiral tris-indanyl molecular rods

    DEFF Research Database (Denmark)

    Kjeldsen, Niels Due; Funder, Erik Daa; Gothelf, Kurt Vesterager

    2014-01-01

    Homochiral tris-indanyl molecular rods designed for supramolecular surface self-assembly were synthesized. The chiral indanol moiety was constructed via a Ti-mediated alkyne trimerization. Further manipulations resulted in a homochiral indanol monomer. This was employed as the precursor for succe...... for successive Sonogashira and Ohira-Bestman reactions towards the homochiral tris-indanyl molecular rods. The molecular rods will be applied for scanning tunnelling microscopy studies of their surface self-assembly and chirality.......Homochiral tris-indanyl molecular rods designed for supramolecular surface self-assembly were synthesized. The chiral indanol moiety was constructed via a Ti-mediated alkyne trimerization. Further manipulations resulted in a homochiral indanol monomer. This was employed as the precursor...

  3. Nigerian Journal of Chemical Research Vol.12, 2007 Synthesis and ...

    African Journals Online (AJOL)

    HP USER

    Schiff base ligands play an important role in the development of coordination chemistry related to catalysis and enzymatic reactions, magnetism and molecular architecture. One of the typical examples is the study of the effect of lateral hydroxyl group on mesomorphism of azobenzene derivatives15-23. In the present paper, ...

  4. Activation of aluminum as an effective reducing agent by pitting corrosion for wet-chemical synthesis.

    Science.gov (United States)

    Li, Wei; Cochell, Thomas; Manthiram, Arumugam

    2013-01-01

    Metallic aluminum (Al) is of interest as a reducing agent because of its low standard reduction potential. However, its surface is invariably covered with a dense aluminum oxide film, which prevents its effective use as a reducing agent in wet-chemical synthesis. Pitting corrosion, known as an undesired reaction destroying Al and is enhanced by anions such as F⁻, Cl⁻, and Br⁻ in aqueous solutions, is applied here for the first time to activate Al as a reducing agent for wet-chemical synthesis of a diverse array of metals and alloys. Specifically, we demonstrate the synthesis of highly dispersed palladium nanoparticles on carbon black with stabilizers and the intermetallic Cu₂Sb/C, which are promising candidates, respectively, for fuel cell catalysts and lithium-ion battery anodes. Atomic hydrogen, an intermediate during the pitting corrosion of Al in protonic solvents (e.g., water and ethylene glycol), is validated as the actual reducing agent.

  5. On Medium Chemical Reaction in Diffusion-Based Molecular Communication: a Two-Way Relaying Example

    OpenAIRE

    Farahnak-Ghazani, Maryam; Aminian, Gholamali; Mirmohseni, Mahtab; Gohari, Amin; Nasiri-Kenari, Masoumeh

    2016-01-01

    Chemical reactions are a prominent feature of molecular communication (MC) systems, with no direct parallels in wireless communications. While chemical reactions may be used inside the transmitter nodes, receiver nodes or the communication medium, we focus on its utility in the medium in this paper. Such chemical reactions can be used to perform computation over the medium as molecules diffuse and react with each other (physical-layer computation). We propose the use of chemical reactions for...

  6. Chemical synthesis, characterization and evaluation of antimicrobial properties of Cu and its oxide nanoparticles

    CSIR Research Space (South Africa)

    Motlatle, Abesach M

    2016-10-01

    Full Text Available of Nanoparticle Research, vol. 18: DOI: 10.1007/s11051-016-3614-8 Chemical synthesis, characterization and evaluation of antimicrobial properties of Cu and its oxide nanoparticles Motlatle AM Kesevan Pillai S Scriba MR Ray SS ABSTRACT: Cu...

  7. Chemical synthesis of membrane proteins by the removable backbone modification method.

    Science.gov (United States)

    Tang, Shan; Zuo, Chao; Huang, Dong-Liang; Cai, Xiao-Ying; Zhang, Long-Hua; Tian, Chang-Lin; Zheng, Ji-Shen; Liu, Lei

    2017-12-01

    Chemical synthesis can produce membrane proteins bearing specifically designed modifications (e.g., phosphorylation, isotope labeling) that are difficult to obtain through recombinant protein expression approaches. The resulting homogeneously modified synthetic membrane proteins are valuable tools for many advanced biochemical and biophysical studies. This protocol describes the chemical synthesis of membrane proteins by condensation of transmembrane peptide segments through native chemical ligation. To avoid common problems encountered due to the poor solubility of transmembrane peptides in almost any solvent, we describe an effective procedure for the chemical synthesis of membrane proteins through the removable-backbone modification (RBM) strategy. Two key steps of this protocol are: (i) installation of solubilizing Arg4-tagged RBM groups into the transmembrane peptides at any primary amino acid through Fmoc (9-fluorenylmethyloxycarbonyl) solid-phase peptide synthesis and (ii) native ligation of the full-length sequence, followed by removal of the RBM tags by TFA (trifluoroacetic acid) cocktails to afford the native protein. The installation of RBM groups is achieved by using 4-methoxy-5-nitrosalicyladehyde by reduction amination to incorporate an activated O-to-N acyl transfer auxiliary. The Arg4-tag-modified membrane-spanning peptide segments behave like water-soluble peptides to facilitate their purification, ligation and mass characterization.

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

    Science.gov (United States)

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

    2010-11-21

    Here we report the total synthesis of kaliotoxin by 'one pot' native chemical ligation of three synthetic peptides. A racemic mixture of D- and L-kaliotoxin synthetic protein molecules gave crystals in the centrosymmetric space group P1 that diffracted to atomic-resolution (0.95 Å), enabling the X-ray structure of kaliotoxin to be determined by direct methods.

  9. A wet-chemical approach to perovskite and fluorite-type nanoceramics: synthesis and processing

    NARCIS (Netherlands)

    Veldhuis, Sjoerd

    2015-01-01

    In thesis the low-temperature, wet-chemical approach to various functional inorganic oxide materials is described. The main focus of this research is to control the material’s synthesis from liquid precursor to metal oxide powder or thin film; while understanding its formation mechanism. In

  10. Synthesis of Polyimides in Molecular-Scale Confinement for Low-Density Hybrid Nanocomposites.

    Science.gov (United States)

    Isaacson, Scott G; Fostvedt, Jade I; Koerner, Hilmar; Baur, Jeffery W; Lionti, Krystelle; Volksen, Willi; Dubois, Geraud; Dauskardt, Reinhold H

    2017-11-08

    In this work, we exploit a confinement-induced molecular synthesis and a resulting bridging mechanism to create confined polyimide thermoset nanocomposites that couple molecular confinement-enhanced toughening with an unprecedented combination of high-temperature properties at low density. We describe a synthesis strategy that involves the infiltration of individual polymer chains through a nanoscale porous network while simultaneous imidization reactions increase the molecular backbone stiffness. In the extreme limit where the confinement length scale is much smaller than the polymer's molecular size, confinement-induced molecular mechanisms give rise to exceptional mechanical properties. We find that polyimide oligomers can undergo cross-linking reactions even in such molecular-scale confinement, increasing the molecular weight of the organic phase and toughening the nanocomposite through a confinement-induced energy dissipation mechanism. This work demonstrates that the confinement-induced molecular bridging mechanism can be extended to thermoset polymers with multifunctional properties, such as excellent thermo-oxidative stability and high service temperatures (>350 °C).

  11. Synthesis of graphene platelets by chemical and electrochemical route

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, Rajendran; Felix, Sathiyanathan [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Joshi, Girish M. [Materials Physics Division, School of Advanced Sciences, VIT University, Vellore 632014, Tamil Nadu (India); Raghupathy, Bala P.C., E-mail: balapraveen2000@yahoo.com [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Research and Advanced Engineering Division (Materials), Renault Nissan Technology and Business Center India (P) Ltd., Chennai, Tamil Nadu (India); Jeong, Soon Kwan, E-mail: jeongsk@kier.re.kr [Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Grace, Andrews Nirmala, E-mail: anirmalagrace@vit.ac.in [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2013-10-15

    Graphical abstract: A schematic showing the overall reduction process of graphite to reduced graphene platelets by chemical and electrochemical route. - Highlights: • Graphene was prepared by diverse routes viz. chemical and electrochemical methods. • NaBH{sub 4} was effective for removing oxygen functional groups from graphene oxide. • Sodium borohydride reduced graphene oxide (SRGO) showed high specific capacitance. • Electrochemical rendered a cheap route for production of graphene in powder form. - Abstract: Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide.

  12. Application of mechano-chemical synthesis for protective coating

    Indian Academy of Sciences (India)

    This can either be prevented by using grinding medium and container of same material of the milled material or by adding a coating of the milled material on them. The paper describes the observations made during a mechano-chemical reaction, being used for coating the balls and vials in a planetary ball mill.

  13. Synthesis of graphene platelets by chemical and electrochemical route

    International Nuclear Information System (INIS)

    Ramachandran, Rajendran; Felix, Sathiyanathan; Joshi, Girish M.; Raghupathy, Bala P.C.; Jeong, Soon Kwan; Grace, Andrews Nirmala

    2013-01-01

    Graphical abstract: A schematic showing the overall reduction process of graphite to reduced graphene platelets by chemical and electrochemical route. - Highlights: • Graphene was prepared by diverse routes viz. chemical and electrochemical methods. • NaBH 4 was effective for removing oxygen functional groups from graphene oxide. • Sodium borohydride reduced graphene oxide (SRGO) showed high specific capacitance. • Electrochemical rendered a cheap route for production of graphene in powder form. - Abstract: Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide

  14. Synthesis and molecular docking of new hydrazones derived from ...

    African Journals Online (AJOL)

    Methods: The reaction of ethyl isonipecotate (2) with 3 ... All the synthesized compounds were structurally elucidated by proton nuclear magnetic ... International Pharmaceutical Abstract, Chemical Abstracts, Embase, Index Copernicus, ...

  15. A chemical platform approach on cardanol oil: from the synthesis of building blocks to polymer synthesis

    Directory of Open Access Journals (Sweden)

    Jaillet Fanny

    2016-09-01

    Full Text Available This review proposes a platform approach for the synthesis of various building blocks from cardanol oil in one or two-steps synthesis. Cardanol is a natural phenol issued from Cashew nutshell liquid (CNSL. CNSL is a non-edible renewable resource, co-produced from cashew industry in large commercial volumes. Cardanol is non-toxic and particularly suitable as an aromatic renewable resource for polymers and materials. Various routes were used for the synthesis of di- and poly-functional building blocks used thereafter in polymer syntheses. Phenolation was used to dimerize/oligomerize cardanol to propose increase functionality of cardanol. Thio-ene was used to synthesize new reactive amines. Epoxidation and (methacrylation were also used to insert oxirane or (methacrylate groups in order to synthesize polymers and materials.

  16. Catalytic chemical amide synthesis at room temperature: one more step toward peptide synthesis.

    Science.gov (United States)

    Mohy El Dine, Tharwat; Erb, William; Berhault, Yohann; Rouden, Jacques; Blanchet, Jérôme

    2015-05-01

    An efficient method has been developed for direct amide bond synthesis between carboxylic acids and amines via (2-(thiophen-2-ylmethyl)phenyl)boronic acid as a highly active bench-stable catalyst. This catalyst was found to be very effective at room temperature for a large range of substrates with slightly higher temperatures required for challenging ones. This methodology can be applied to aliphatic, α-hydroxyl, aromatic, and heteroaromatic acids as well as primary, secondary, heterocyclic, and even functionalized amines. Notably, N-Boc-protected amino acids were successfully coupled in good yields with very little racemization. An example of catalytic dipeptide synthesis is reported.

  17. Boronate esters: Synthesis, characterization and molecular base receptor analysis

    Science.gov (United States)

    Gómez-Jaimes, Gelen; Barba, Victor

    2014-10-01

    The synthesis of three boronate esters obtained by reacting 4-fluorophenylboronic (1), 4-iodophenylboronic (2) and 3,4-chlorophenylboronic (3) acids with 2,4,5-trihidroxybenzaldehyde is reported. The structural characterization was determined by spectroscopic and spectrometric techniques. The boron atom was evaluated to acts as Lewis acid center in the reaction with pyridine (Py), triethylamine (TEA) and fluoride anion (F-). The titration method was followed by UV-Vis and 11B NMR spectroscopy; results indicate the good interaction with the fluoride ion but poor coordination towards pyridine in solution.

  18. Understanding the Synthesis and Properties of Molecular Silver Nanoparticles

    Science.gov (United States)

    Ashenfelter, Brian A.

    Molecular nanoparticles have emerged as an interesting class of materials whose atomically precise structures and discrete properties set them apart from their larger counterparts. Molecular silver nanoparticles are of particular interest because they provide a host of advantages as optical materials for possible use in sensing and imaging applications. However, relatively little is known about molecular silver nanoparticles including the details of their formation and their optical and mechanical properties. Size control remains a longstanding challenge in the production of glutathionate (SG) protected silver nanoparticles. Singular Ag:SG nanoparticle products have been difficult to obtain directly, but size focusing of larger distributions through attrition has been found to lead to useful isolation of particular species. Here, we present a methodology for controlling the size of Ag:SG molecular nanoparticles that leverages the stability of the most robust species. These results were then used to develop a facile approach for achieving two of the most stable species in the Ag:SG system. Molecular metal nanoparticles are known to be much more fluorescent than larger plasmonic nanoparticles, however the nature and origin of this fluorescence are not fully understood. Fluorescence can originate from either the quantum states within the metal core or mixed ligand states at the inorganic-organic interface. We have presented compelling evidence that fluorescence from molecular silver glutathionate nanoparticles has its origin in interfacial electronic states. Fluorescence spectra were found to be independent of size, with very similar wavelength and bandwidth, although the quantum yield was not. Excitation spectra indicated that the strongest fluorescence had its origin in that part of the spectrum that is dominated by ligand-related states. Further, excitations to strictly core states and to higher lying d-band states had little to no contribution to the fluorescence

  19. Total synthesis of cytochrome b562 by native chemical ligation using a removable auxiliary

    Science.gov (United States)

    Low, Donald W.; Hill, Michael G.; Carrasco, Michael R.; Kent, Stephen B. H.; Botti, Paolo

    2001-01-01

    We have completed the total chemical synthesis of cytochrome b562 and an axial ligand analogue, [SeMet7]cyt b562, by thioester-mediated chemical ligation of unprotected peptide segments. A novel auxiliary-mediated native chemical ligation that enables peptide ligation to be applied to protein sequences lacking cysteine was used. A cleavable thiol-containing auxiliary group, 1-phenyl-2-mercaptoethyl, was added to the α-amino group of one peptide segment to facilitate amide bond-forming ligation. The amine-linked 1-phenyl-2-mercaptoethyl auxiliary was stable to anhydrous hydrogen fluoride used to cleave and deprotect peptides after solid-phase peptide synthesis. Following native chemical ligation with a thioester-containing segment, the auxiliary group was cleanly removed from the newly formed amide bond by treatment with anhydrous hydrogen fluoride, yielding a full-length unmodified polypeptide product. The resulting polypeptide was reconstituted with heme and folded to form the functional protein molecule. Synthetic wild-type cyt b562 exhibited spectroscopic and electrochemical properties identical to the recombinant protein, whereas the engineered [SeMet7]cyt b562 analogue protein was spectroscopically and functionally distinct, with a reduction potential shifted by ≈45 mV. The use of the 1-phenyl-2-mercaptoethyl removable auxiliary reported here will greatly expand the applicability of total protein synthesis by native chemical ligation of unprotected peptide segments. PMID:11390992

  20. Analysing chemical equilibrium conditions when studying butyl acetate synthesis

    OpenAIRE

    Álvaro Orjuela Londoño; Fernando Leiva Lenis; Luis Alejandro Boyacá Mendivelso; Gerardo Rodríguez Niño; Luis María Carballo Suárez

    2010-01-01

    This work studied the liquid phase of acetic acid and butyl alcohol esterification reaction (P atm = 560 mmHg),using an ion exchange resin (Lewatit K-2431) as catalyst. A set of assays were carried out for determining the effect of catalyst load, temperature and molar ratio (acid/alcohol) on chemical equilibrium constant. Components’ selective sorption on the resin matrix was noticed; its effect on equilibrium conditions was verified, by using different acid/alcohol starting ratios. A non-ide...

  1. Nanostructured conjugated polymers in chemical sensors: synthesis, properties and applications.

    Science.gov (United States)

    Correa, D S; Medeiros, E S; Oliveira, J E; Paterno, L G; Mattoso, Luiz C

    2014-09-01

    Conjugated polymers are organic materials endowed with a π-electron conjugation along the polymer backbone that present appealing electrical and optical properties for technological applications. By using conjugated polymeric materials in the nanoscale, such properties can be further enhanced. In addition, the use of nanostructured materials makes possible miniaturize devices at the micro/nano scale. The applications of conjugated nanostructured polymers include sensors, actuators, flexible displays, discrete electronic devices, and smart fabric, to name a few. In particular, the use of conjugated polymers in chemical and biological sensors is made feasible owning to their sensitivity to the physicochemical conditions of its surrounding environment, such as chemical composition, pH, dielectric constant, humidity or even temperature. Subtle changes in these conditions bring about variations on the electrical (resistivity and capacitance), optical (absorptivity, luminescence, etc.), and mechanical properties of the conjugated polymer, which can be precisely measured by different experimental methods and ultimately associated with a specific analyte and its concentration. The present review article highlights the main features of conjugated polymers that make them suitable for chemical sensors. An especial emphasis is given to nanostructured sensors systems, which present high sensitivity and selectivity, and find application in beverage and food quality control, pharmaceutical industries, medical diagnosis, environmental monitoring, and homeland security, and other applications as discussed throughout this review.

  2. Mapping the dark space of chemical reactions with extended nanomole synthesis and MALDI-TOF MS.

    Science.gov (United States)

    Lin, Shishi; Dikler, Sergei; Blincoe, William D; Ferguson, Ronald D; Sheridan, Robert P; Peng, Zhengwei; Conway, Donald V; Zawatzky, Kerstin; Wang, Heather; Cernak, Tim; Davies, Ian W; DiRocco, Daniel A; Sheng, Huaming; Welch, Christopher J; Dreher, Spencer D

    2018-05-24

    Understanding the practical limitations of chemical reactions is critically important for efficiently planning the synthesis of compounds in pharmaceutical, agrochemical and specialty chemical research and development. However, literature reports of the scope of new reactions are often cursory and biased toward successful results, severely limiting the ability to predict reaction outcomes for untested substrates. We herein illustrate strategies for carrying out large scale surveys of chemical reactivity using a material-sparing nanomole-scale automated synthesis platform with greatly expanded synthetic scope combined with ultra-high throughput (uHT) matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Copyright © 2018, American Association for the Advancement of Science.

  3. Automatic reactor for solid-phase synthesis of molecularly imprinted polymeric nanoparticles (MIP NPs) in water.

    Science.gov (United States)

    Poma, Alessandro; Guerreiro, Antonio; Caygill, Sarah; Moczko, Ewa; Piletsky, Sergey

    We report the development of an automated chemical reactor for solid-phase synthesis of MIP NPs in water. Operational parameters are under computer control, requiring minimal operator intervention. In this study, "ready for use" MIP NPs with sub-nanomolar affinity are prepared against pepsin A, trypsin and α-amylase in only 4 hours.

  4. Automatic reactor for solid-phase synthesis of molecularly imprinted polymeric nanoparticles (MIP NPs) in water

    OpenAIRE

    Poma, Alessandro; Guerreiro, Antonio; Caygill, Sarah; Moczko, Ewa; Piletsky, Sergey

    2014-01-01

    We report the development of an automated chemical reactor for solid-phase synthesis of MIP NPs in water. Operational parameters are under computer control, requiring minimal operator intervention. In this study, “ready for use” MIP NPs with sub-nanomolar affinity are prepared against pepsin A, trypsin and α-amylase in only 4 hours.

  5. Chemical and Molecular Characterization of Biofilm on Metal Surfaces

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.

    analytical instrumental techniques to assess the kinetics and chemical composition of the conditioning film developed on stainless steel panels deployed in seawater. These studies suggest that proteins are the first compounds to adsorb onto stainless steel...., 1990; Bott 1993; 159 stainless steel by the Time of flight secondary ion mass spectrometer (ToF-SIMS) (Poleunis et al., 2002, 2003). Further the nature of the substratum influences the chemical composition and quality of adsorbed organic matter...

  6. Immobilization methods for the rapid total chemical synthesis of proteins on microtiter plates.

    Science.gov (United States)

    Zitterbart, Robert; Krumrey, Michael; Seitz, Oliver

    2017-07-01

    The chemical synthesis of proteins typically involves the solid-phase peptide synthesis of unprotected peptide fragments that are stitched together in solution by native chemical ligation (NCL). The process is slow, and throughput is limited because of the need for repeated high performance liquid chromatography purification steps after both solid-phase peptide synthesis and NCL. With an aim to provide faster access to functional proteins and to accelerate the functional analysis of synthetic proteins by parallelization, we developed a method for the high performance liquid chromatography-free synthesis of proteins on the surface of microtiter plates. The method relies on solid-phase synthesis of unprotected peptide fragments, immobilization of the C-terminal fragment and on-surface NCL with an unprotected peptide thioester in crude form. Herein, we describe the development of a suitable immobilization chemistry. We compared (i) formation of nickel(II)-oligohistidine complexes, (ii) Cu-based [2 + 3] alkine-azide cycloaddition and (iii) hydrazone ligation. The comparative study identified the hydrazone ligation as most suitable. The sequence of immobilization via hydrazone ligation, on-surface NCL and radical desulfurization furnished the targeted SH3 domains in near quantitative yield. The synthetic proteins were functional as demonstrated by an on-surface fluorescence-based saturation binding analysis. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

  7. MCM-41 ordered mesoporous molecular sieves synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Rogério A.A. Melo

    1999-07-01

    Full Text Available The aim of this work was to study the hydrothermal synthesis of Si and SiAlMCM-41 performed under both autogenic pressure and refluxing conditions. XRD data showed that the MCM-41 phase may be formed by both processes and that the synthesized material in the presence of Al and/or under reflux presents the hexagonally arrangement of less ordered mesopores. However, as verified by XRD and physisorption data, the order was improved with higher synthesis times. 29Si and 1H - 29Si C/P MAS NMR spectra showed that a great part of the Si atoms exists as silanol groups which originate resonance peaks at -110, -100 and -91 ppm. The presence of Al atoms may generate Si(3Si, Al and Si(2Si, 2Al environments which might be contributing to resonance peaks at -100 and -91 ppm. The 27Al MAS NMR spectrum of the as synthesized AlSiMCM-41 showed a resonance peak of tetrahedral framework aluminum close to 53 ppm and two others, one close to 14 ppm attributed to Al(H2O6+3 species and the other a weak signal close to 32 ppm attributed to pentacoordinated Al. 27Al MAS NMR spectra of the calcined sample showed a peak at 0 ppm corresponding to an hexacoordinated extra-framework aluminum formed during calcination.

  8. Synthesis, anti-microbial activity and molecular docking studies on ...

    Indian Academy of Sciences (India)

    Molecular structures of triazolylcoumarins 1–8. method and are ... organic layer was washed with water (100 mL) and sat- ... (0.5mmol) in a mixture of THF and water (1:1) solution. ..... for docking studies with the target DNA gyrase B (PDB.

  9. From Chemical Topology to Molecular Machines (Nobel Lecture).

    Science.gov (United States)

    Sauvage, Jean-Pierre

    2017-09-04

    To a large extent, the field of "molecular machines" started after several groups were able to prepare, reasonably easily, interlocking ring compounds (named catenanes for compounds consisting of interlocking rings and rotaxanes for rings threaded by molecular filaments or axes). Important families of molecular machines not belonging to the interlocking world were also designed, prepared, and studied but, for most of them, their elaboration was more recent than that of catenanes or rotaxanes. Since the creation of interlocking ring molecules is so important in relation to the molecular machinery area, we will start with this aspect of our work. The second part will naturally be devoted to the dynamic properties of such systems and to the compounds for which motions can be directed in a controlled manner from the outside, that is, molecular machines. We will restrict our discussion to a very limited number of examples which we consider as particularly representative of the field. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Post-synthesis amine borane functionalization of metal-organic framework and its unusual chemical hydrogen release phenomenon

    KAUST Repository

    Berke, Heinz

    2017-05-11

    We report a novel strategy for post-synthesis amine borane functionalization of MOFs under gas-solid phase transformation utilizing gaseous diborane. The covalently confined amine borane derivative decorated on the framework backbone is stable when preserved at low temperature, but spontaneously liberates soft chemical hydrogen at room temperature leading to the development of an unusual borenium type species (-NH=BH2+) ion-paired with hydroborate anion. Furthermore, the unsaturated amino borane (-NH=BH2) and the -iminodiborane ((--NHB2H5) were detected as final products. A combination of DFT based molecular dynamics simulations and solid state NMR spectroscopy, utilizing isotopically enriched materials, were undertaken to unequivocally elucidate the mechanistic pathways for H2 liberation.

  11. Use of carbonates for biological and chemical synthesis

    Science.gov (United States)

    Rau, Gregory Hudson

    2014-09-09

    A system of using carbonates, especially water-insoluble or sparing soluble mineral carbonates, for maintaining or increasing dissolved inorganic carbon concentrations in aqueous media. In particular, the system generates concentrated dissolve inorganic carbon substrates for photosynthetic, chemosynthetic, or abiotic chemical production of carbonaceous or other compounds in solution. In some embodiments, the invention can also enhance the dissolution and retention of carbon dioxide in aqueous media, and can produce pH buffering capacity, metal ions, and heat, which can be beneficial to the preceding syntheses.

  12. Synthesis of Lead Sulfide Nanoparticles by Chemical Precipitation Method

    International Nuclear Information System (INIS)

    Chongad, L S; Sharma, A; Banerjee, M; Jain, A

    2016-01-01

    Lead sulfide (PbS) nanoparticles were prepared by chemical precipitation method (CPM) with the assistance of H 2 S gas. The microstructure and morphology of the synthesized nanoparticles have been investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the PbS nanoparticles reveal formation of cubic phase. To investigate the quality of prepared nanoparticles, the particles size, lattice constant, strain, dislocation density etc. have been determined using XRD. TEM images reveal formation of cubic nanoparticles and the particle size determined from TEM images agree well with those from XRD. (paper)

  13. Molecular and chemical engineering of bacteriophages for potential medical applications.

    Science.gov (United States)

    Hodyra, Katarzyna; Dąbrowska, Krystyna

    2015-04-01

    Recent progress in molecular engineering has contributed to the great progress of medicine. However, there are still difficult problems constituting a challenge for molecular biology and biotechnology, e.g. new generation of anticancer agents, alternative biosensors or vaccines. As a biotechnological tool, bacteriophages (phages) offer a promising alternative to traditional approaches. They can be applied as anticancer agents, novel platforms in vaccine design, or as target carriers in drug discovery. Phages also offer solutions for modern cell imaging, biosensor construction or food pathogen detection. Here we present a review of bacteriophage research as a dynamically developing field with promising prospects for further development of medicine and biotechnology.

  14. Synthesis and characterization of core–shell magnetic molecularly ...

    Indian Academy of Sciences (India)

    of hormones [24] or chemical compounds [25] and colour identification [26]. ... The magnetic properties were analysed with a vibrating sample magnetometer .... Transmission electron microscopy image of (a) Fe3O4 and (b) Fe3O4@SiO2.

  15. Comparative study between bioapatite and synthetic hydroxyapatite obtained by chemical precipitation and mechanochemical synthesis

    International Nuclear Information System (INIS)

    Quispe M, J.; Moreno, M.; Montano, J.; Pillaca, M.; Guzman, A.; Cavero, A.; Arce, M.

    2009-01-01

    A comparative study between the inorganic component of a human bone tissue with respect of apatite synthesized by chemical precipitation, mechanochemical synthesis and a sample of commercial hidroxyapatite are shown. The samples were studied by X-ray diffraction, atomic absorption spectroscopy and Fourier transform infrared spectroscopy. The results show similar structural characteristics among all samples identifying that sample prepared by mechanochemical synthesis is a kind of hydroxyapatite which has substitutions of carbonate in its crystalline structure, similar to the inorganic component of bone tissue. (author).

  16. A Review of Carbon Nanomaterials’ Synthesis via the Chemical Vapor Deposition (CVD Method

    Directory of Open Access Journals (Sweden)

    Yehia M. Manawi

    2018-05-01

    Full Text Available Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs, carbon nanofibers (CNFs, graphene, carbide-derived carbon (CDC, carbon nano-onion (CNO and MXenes. Furthermore, current challenges in the synthesis and application of these nanomaterials are highlighted with suggested areas for future research.

  17. A Review of Carbon Nanomaterials’ Synthesis via the Chemical Vapor Deposition (CVD) Method

    Science.gov (United States)

    Manawi, Yehia M.; Samara, Ayman; Al-Ansari, Tareq; Atieh, Muataz A.

    2018-01-01

    Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbide-derived carbon (CDC), carbon nano-onion (CNO) and MXenes. Furthermore, current challenges in the synthesis and application of these nanomaterials are highlighted with suggested areas for future research. PMID:29772760

  18. Molecular Modeling as a Self-Taught Component of a Conventional Undergraduate Chemical Reaction Engineering Course

    Science.gov (United States)

    Rothe, Erhard W.; Zygmunt, William E.

    2016-01-01

    We inserted a self-taught molecular modeling project into an otherwise conventional undergraduate chemical-reaction-engineering course. Our objectives were that students should (a) learn with minimal instructor intervention, (b) gain an appreciation for the relationship between molecular structure and, first, macroscopic state functions in…

  19. Developmental co-expression of small molecular weight apolipoprotein B synthesis and triacylglycerol secretion

    International Nuclear Information System (INIS)

    Coleman, R.A.; Haynes, E.B.; Sand, T.M.; Davis, R.A.

    1987-01-01

    The development of the liver's ability to coordinately express the synthesis and secretion of the two major components of very low density lipoproteins (VLDL): triacylglycerol (TG) and apolipoprotein B (apo B) was examined in cultured hepatocytes obtained from fetal, suckling and adult rats. Hepatocytes from fetal and suckling rats synthesized and secreted TG at rates lower than that displayed by adult cells. When TG synthesis was equalized by adding oleic acid to the culture medium, fetal cells still secreted only 39% as much TG as did adult cells. To determine the basis for the apparent defect in VLDL assembly/secretion displayed by fetal cells, the synthesis and secretion of [ 35 S]methionine-labeled apo B was quantified by immunoprecipitation. Although adult and fetal cells synthesized and secreted large molecular weight apo B at similar rates, the synthesis and secretion of small molecular weight apo B was 2-fold greater in adult cells. These data suggest that the ability to assemble/secrete VLDL triacylglycerol varies in parallel with the developmental expression of small molecular weight apo B. Furthermore, these studies show the usefulness of the cultured rat hepatocyte model for examining the ontogeny and regulation of VLDL assembly/secretion

  20. Chemical synthesis and stabilization of magnesium substituted brushite

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Donghyun [Department of Biomedical Engineering, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of); Kumta, Prashant N., E-mail: pkumta@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Mechanical Engineering and Materials Sceince, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15260 (United States)

    2010-08-30

    Hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}) is the most ubiquitous calcium phosphate phase used in implant coatings and more recently in gene/drug delivery applications due to its chemical stability under normal physiological conditions (37 deg. C, pH {approx} 7.5, 1 atm.). However, different calcium phosphate phases, such as brushite (CaH(PO{sub 4}){center_dot}2(H{sub 2}O)) and tricalcium phosphate (Ca{sub 3}(PO{sub 4}){sub 2}) which are thermodynamically unstable under physiological conditions are also being explored for biomedical applications. One way of stabilizing these phases under physiological conditions is to introduce magnesium to substitute for calcium in the brushite lattice. The role of magnesium as a stabilizing agent for synthesizing brushite under physiological conditions at room temperature has been studied. Chemical analysis, Fourier transform infrared spectroscopy and X-ray diffraction have also been conducted to validate the formation of magnesium substituted brushite under physiological conditions.

  1. DESIGN, SYNTHESIS, AND APPLICATION OF THE TRIMETHOPRIM-BASED CHEMICAL TAG FOR LIVE CELL IMAGING

    Science.gov (United States)

    Jing, Chaoran; Cornish, Virginia W.

    2013-01-01

    Over the past decade chemical tags have been developed to complement the use of fluorescent proteins in live cell imaging. Chemical tags retain the specificity of protein labeling achieved with fluorescent proteins through genetic encoding, but provide smaller, more robust tags and modular use of organic fluorophores with high photon-output and tailored functionalities. The trimethoprim-based chemical tag (TMP-tag) was initially developed based on the high affinity interaction between E.coli dihydrofolatereductase and the antibiotic trimethoprim and subsequently rendered covalent and fluorogenic via proximity-induced protein labeling reactions. To date, the TMP-tag is one of the few chemical tags that enable intracellular protein labeling and high-resolution live cell imaging. Here we describe the general design, chemical synthesis, and application of TMP-tag for live cell imaging. Alternative protocols for synthesizing and using the covalent and the fluorogenic TMP-tags are also included. PMID:23839994

  2. Poly[n]catenanes: Synthesis of molecular interlocked chains

    Science.gov (United States)

    Wu, Qiong; Rauscher, Phillip M.; Lang, Xiaolong; Wojtecki, Rudy J.; de Pablo, Juan J.; Hore, Michael J. A.; Rowan, Stuart J.

    2017-12-01

    As the macromolecular version of mechanically interlocked molecules, mechanically interlocked polymers are promising candidates for the creation of sophisticated molecular machines and smart soft materials. Poly[n]catenanes, where the molecular chains consist solely of interlocked macrocycles, contain one of the highest concentrations of topological bonds. We report, herein, a synthetic approach toward this distinctive polymer architecture in high yield (~75%) via efficient ring closing of rationally designed metallosupramolecular polymers. Light-scattering, mass spectrometric, and nuclear magnetic resonance characterization of fractionated samples support assignment of the high-molar mass product (number-average molar mass ~21.4 kilograms per mole) to a mixture of linear poly[7-26]catenanes, branched poly[13-130]catenanes, and cyclic poly[4-7]catenanes. Increased hydrodynamic radius (in solution) and glass transition temperature (in bulk materials) were observed upon metallation with Zn2+.

  3. Evidence for Dynamic Chemical Kinetics at Individual Molecular Ruthenium Catalysts.

    Science.gov (United States)

    Easter, Quinn T; Blum, Suzanne A

    2018-02-05

    Catalytic cycles are typically depicted as possessing time-invariant steps with fixed rates. Yet the true behavior of individual catalysts with respect to time is unknown, hidden by the ensemble averaging inherent to bulk measurements. Evidence is presented for variable chemical kinetics at individual catalysts, with a focus on ring-opening metathesis polymerization catalyzed by the second-generation Grubbs' ruthenium catalyst. Fluorescence microscopy is used to probe the chemical kinetics of the reaction because the technique possesses sufficient sensitivity for the detection of single chemical reactions. Insertion reactions in submicron regions likely occur at groups of many (not single) catalysts, yet not so many that their unique kinetic behavior is ensemble averaged. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Synthesis of mullite coatings by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mulpuri, R.P.; Auger, M.; Sarin, V.K. [Boston Univ., MA (United States)

    1996-08-01

    Formation of mullite on ceramic substrates via chemical vapor deposition was investigated. Mullite is a solid solution of Al{sub 2}O{sub 3} and SiO{sub 2} with a composition of 3Al{sub 2}O{sub 3}{circ}2SiO{sub 2}. Thermodynamic calculations performed on the AlCl{sub 3}-SiCl{sub 4}-CO{sub 2}-H{sub 2} system were used to construct equilibrium CVD phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were determined. Through process optimization, crystalline CVD mullite coatings have been successfully grown on SiC and Si{sub 3}N{sub 4} substrates. Results from the thermodynamic analysis, process optimization, and effect of various process parameters on deposition rate and coating morphology are discussed.

  5. A simple wet chemical synthesis and characterization of hydroxyapatite nanorods

    International Nuclear Information System (INIS)

    Liu Yingkai; Hou Dedong; Wang Guanghou

    2004-01-01

    Calcium hydroxyapatite (Ca 5 (PO 4 ) 3 (OH):HAP) nanorods have been synthesized successfully via wet chemical technique at low temperature in the presence of suitable surfactant. The as-made nanorods have a diameter of 50-80 nm and a length of 0.5-1.2 μm. The microstructures and composition are characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectrometer (FT-IR). The formation mechanism of HAP nanorod is discussed in detail. It has been found that nanorods are pure, there is no HAP carbonated HAP. The growth mechanism of HAP nanorods could be explained by a soft template

  6. Use of Modern Chemical Protein Synthesis and Advanced Fluorescent Assay Techniques to Experimentally Validate the Functional Annotation of Microbial Genomes

    Energy Technology Data Exchange (ETDEWEB)

    Kent, Stephen [University of Chicago

    2012-07-20

    The objective of this research program was to prototype methods for the chemical synthesis of predicted protein molecules in annotated microbial genomes. High throughput chemical methods were to be used to make large numbers of predicted proteins and protein domains, based on microbial genome sequences. Microscale chemical synthesis methods for the parallel preparation of peptide-thioester building blocks were developed; these peptide segments are used for the parallel chemical synthesis of proteins and protein domains. Ultimately, it is envisaged that these synthetic molecules would be ‘printed’ in spatially addressable arrays. The unique ability of total synthesis to precision label protein molecules with dyes and with chemical or biochemical ‘tags’ can be used to facilitate novel assay technologies adapted from state-of-the art single molecule fluorescence detection techniques. In the future, in conjunction with modern laboratory automation this integrated set of techniques will enable high throughput experimental validation of the functional annotation of microbial genomes.

  7. Radiochemical problems of radiation chemical synthesis in n, γ-field of nuclear reactor

    International Nuclear Information System (INIS)

    Mironov, V.P.; Frejdus, N.V.; Bugaenko, L.T.; Kalyazin, E.P.; Petryaev, E.P.

    1981-01-01

    A wide applicability of products of radiation chemical synthesis (RCS), using n, γ-irradiation, is limited by possible contamination of the latter with long-lived radioactive isotopes of chemical elements included in the composition of the reagent and compounds syntesized (chemically non-separable radionuclides - CNR). A technique of the determination of the limit accumulation CNR on the basis of radiation chemical parameters of the synthesis (radiation-chemical yield, the dose rate absorbed, singleness of purpose of RCS etc.) and radiochemical parameters of formation and accumulation of CNR (radiochemical yields of CNR in the products of radiolysis, neutron fluence, the reagent purity etc.) is suggested. The radiochemical evaluation of CNR accumulation (tritium and carbon-14), formed at the expense of activation with neutrons of chemical elements of water and organic substances, consisting of hydrogen, carbon and oxygen has shown that at relatively low yields of final products (> or approximately 3 molecules/100 eV) no accumulation of radionuclides in concentrations reaching the average admissible concentration takes place [ru

  8. Chemical Space: Big Data Challenge for Molecular Diversity.

    Science.gov (United States)

    Awale, Mahendra; Visini, Ricardo; Probst, Daniel; Arús-Pous, Josep; Reymond, Jean-Louis

    2017-10-25

    Chemical space describes all possible molecules as well as multi-dimensional conceptual spaces representing the structural diversity of these molecules. Part of this chemical space is available in public databases ranging from thousands to billions of compounds. Exploiting these databases for drug discovery represents a typical big data problem limited by computational power, data storage and data access capacity. Here we review recent developments of our laboratory, including progress in the chemical universe databases (GDB) and the fragment subset FDB-17, tools for ligand-based virtual screening by nearest neighbor searches, such as our multi-fingerprint browser for the ZINC database to select purchasable screening compounds, and their application to discover potent and selective inhibitors for calcium channel TRPV6 and Aurora A kinase, the polypharmacology browser (PPB) for predicting off-target effects, and finally interactive 3D-chemical space visualization using our online tools WebDrugCS and WebMolCS. All resources described in this paper are available for public use at www.gdb.unibe.ch.

  9. Molecular modeling for the design of novel performance chemicals and materials

    CERN Document Server

    Rai, Beena

    2012-01-01

    Molecular modeling (MM) tools offer significant benefits in the design of industrial chemical plants and material processing operations. While the role of MM in biological fields is well established, in most cases MM works as an accessory in novel products/materials development rather than a tool for direct innovation. As a result, MM engineers and practitioners are often seized with the question: ""How do I leverage these tools to develop novel materials or chemicals in my industry?"" Molecular Modeling for the Design of Novel Performance Chemicals and Materials answers this important questio

  10. Molecular building blocks and their architecture in biologically/environmentally compatible soft matter chemical machinery.

    Science.gov (United States)

    Toyota, Taro; Banno, Taisuke; Nitta, Sachiko; Takinoue, Masahiro; Nomoto, Tomonori; Natsume, Yuno; Matsumura, Shuichi; Fujinami, Masanori

    2014-01-01

    This review briefly summarizes recent developments in the construction of biologically/environmentally compatible chemical machinery composed of soft matter. Since environmental and living systems are open systems, chemical machinery must continuously fulfill its functions not only through the influx and generation of molecules but also via the degradation and dissipation of molecules. If the degradation or dissipation of soft matter molecular building blocks and biomaterial molecules/polymers can be achieved, soft matter particles composed of them can be used to realize chemical machinery such as selfpropelled droplets, drug delivery carriers, tissue regeneration scaffolds, protocell models, cell-/tissuemarkers, and molecular computing systems.

  11. Procafd: Computer Aided Tool for Synthesis-Design & Analysis of Chemical Process Flowsheets

    DEFF Research Database (Denmark)

    Kumar Tula, Anjan; Eden, Mario R.; Gani, Rafiqul

    2015-01-01

    and emission to the surrounding and many more. In terms of approaches to solve the synthesis-design problem three major lines of attack have emerged: (a) the knowledge based approach [1] which relies on engineering knowledge & problem insights, (b) the optimization approach [2] which relies on the use...... of mathematical programming techniques, (c) hybrid approach which combine two or more approaches. D’Anterroches [3] proposed a group contribution based hybrid approach to solve the synthesis-design problem where, chemical process flowsheets could be synthesized in the same way as atoms or groups of atoms...... parameters for the operations of the high ranked flowsheets are established through reverse engineering approaches based on driving forces available for each operation. In the final stage, rigorous simulation is performed to validate the synthesis-design. Note that since the flowsheet is synthesized...

  12. Synthesis of a Molecularly Imprinted Polymer for Dioxin

    Directory of Open Access Journals (Sweden)

    Magda Brattoli

    2006-08-01

    Full Text Available A molecularly imprinted polymer for recognising selectively 2,3,7,8-tetrachlorodibenzodioxin (TCDD was made by a new non-covalent method employing a“dummy” template. The proposed way represents a simplification of a synthetic schemeproposed by Lübke et al.[1] for covalent imprinting. Comparison of extraction yields of thenovel polymer, a non imprinted polymer and an imprinting polymer, prepared by theoriginal procedure demonstrates the binding capacity of the proposed polymer, which is inprinciple applicable to solid phase extraction (SPE of dioxin.

  13. Chemical effects induced by ion implantation in molecular solids

    International Nuclear Information System (INIS)

    Foti, G.; Calcagno, L.; Puglisi, O.

    1983-01-01

    Ion implantation in molecular solids as ice, frozen noble gases, benzene and polymers produces a large amount of new molecules compared to the starting materials. Mass and energy analysis of ejected molecules together with the erosion yield, are discussed for several ion-target combinations at low temperature. The observed phenomena are analyzed in terms of deposited ennergy in electronic and nuclear collisions, for incoming beams, as helium or argon, in the range 10-2000 keV. (orig.)

  14. Synthesis and characterization of carbon nanofilms for chemical sensing

    Science.gov (United States)

    Kumar, Vivek

    Carbon nanofilms obtained by high temperature graphitization of diamond surface in inert atmospheres or vacuum are modified by treatment in plasma of different precursor gases. At temperatures above 1000 °C, a stable conductive film of thickness between 10 - 100 nm and specific resistivity 10-3-10-4 Ωm, depending upon the heating conditions and the growth atmosphere, is formed on diamond surface. A gray, thin film of high surface resistivity is obtained in high vacuum, while at low vacuum (below 10-4 mbar), a thick black film of low surface resistivity forms. It is observed that the exposure to plasma reduces the surface conductance of carbon nanofilms as result of a partial removal of carbon and the plasma-stimulated amorphization. The rate of the reduction of conductance and hence the etching ability of plasma depends on the type of precursor gas. Hydrogen reveals the strongest etching ability, followed by oxygen and argon, whereas SF6 is ineffective. The carbon nanofilms show significant sensitivity of their electrical conductance to temperature and exposure to the vapors of common organic compounds. The oxygen plasma treated films exhibit selective response to acetone and water vapors. The fast response and recovery of the conductance are the features of the carbon nanofilms. The plasma-treated carbon nanofilm on graphitized diamond surface is discussed as a promising sensing material for development of all-carbon chemical sensors, which may be suitable for biological and medical applications. An alternative approach of fabrication of temperature and chemical sensitive carbon nanofilms on insulating substrates is proposed. The films are obtained by direct deposition of sputtered carbon on highly polished quartz substrates followed by subsequent annealing at temperatures above 400 °C. It is observed that the as-deposited films are essentially amorphous, while the heating induces irreversible structural ordering and gradual conversion of amorphous carbon in

  15. Molecular cluster theory of chemical bonding in actinide oxide

    International Nuclear Information System (INIS)

    Ellis, D.E.; Gubanov, V.A.; Rosen, A.

    1978-01-01

    The electronic structure of actinide monoxides AcO and dioxides AcO 2 , where Ac = Th, U, Np, Pu, Am, Cm and Bk has been studied by molecular cluster methods based on the first-principles one-electron local density theory. Molecular orbitals for nearest neighbor clusters AcO 10- 6 and AcO 12- 8 representative of monoxide and dioxide lattices were obtained using non-relativistic spin-restricted and spin-polarized Hartree-Fock-Slater models for the entire series. Fully relativistic Dirac-Slater calculations were performed for ThO, UO and NpO in order to explore magnitude of spin-orbit splittings and level shifts in valence structure. Self-consistent iterations were carried out for NpO, in which the NpO 6 cluster was embedded in the molecular field of the solid. Finally, a ''moment polarized'' model which combines both spin-polarization and relativistic effects in a consistent fashion was applied to the NpO system. Covalent mixing of oxygen 2p and Ac 5f orbitals was found to increase rapidly across the actinide series; metal s,p,d covalency was found to be nearly constant. Mulliken atomic population analysis of cluster eigenvectors shows that free-ion crystal field models are unreliable, except for the light actinides. X-ray photoelectron line shapes have been calculated and are found to compare rather well with experimental data on the dioxides

  16. Synthesis of reference compounds related to Chemical Weapons Convention for verification and drug development purposes – a Brazilian endeavour

    Science.gov (United States)

    Cavalcante, S. F. A.; de Paula, R. L.; Kitagawa, D. A. S.; Barcellos, M. C.; Simas, A. B. C.; Granjeiro, J. M.

    2018-03-01

    This paper deals with challenges that Brazilian Army Organic Synthesis Laboratory has been going through to access reference compounds related to the Chemical Weapons Convention in order to support verification analysis and for research of novel antidotes. Some synthetic procedures to produce the chemicals, as well as Quality Assurance issues and a brief introduction of international agreements banning chemical weapons are also presented.

  17. Uranium complexes with macrosyclic polyethers. Synthesis and structural chemical analysis

    International Nuclear Information System (INIS)

    Elbasyouny, A.

    1983-01-01

    This dissertation reports about studies on the chemical coordination behaviour of uranium of oxidation stages IV and VI with regard to twelve different macrocyclic ligands. For the preparation of the complexes, for every system a different method has been developed. The elementary analysis of the various complexes including the uranium had been done by X-ray fluorescence analysis, and the structural characterization proceeded via vibrational, uv-vis and emission spectroscopy as well as 1 H-NMR and 13 C-spin-lattice relaxation time studies. Conformational analysis of the polyethers used allowed the structural changes in the complexes to be observed. The structural analysis of the hydrous uranium VI crown ether complexes yielded information of characteristic features of these types of complexes. The first coordination sphere of the uranyl ion with covalently bonded anion remains unchanged. As to the water content, there is a certain range. Depending upon the solvent used, the complexes have two or four H 2 O molecules per formula unit. (orig./EF) [de

  18. Alternate fuels and chemicals from synthesis gas: Vinyl acetate monomer. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Richard D. Colberg; Nick A. Collins; Edwin F. Holcombe; Gerald C. Tustin; Joseph R. Zoeller

    1999-01-01

    There has been a long-standing desire on the part of industry and the U.S. Department of Energy to replace the existing ethylene-based vinyl acetate monomer (VAM) process with an entirely synthesis gas-based process. Although there are a large number of process options for the conversion of synthesis gas to VAM, Eastman Chemical Company undertook an analytical approach, based on known chemical and economic principles, to reduce the potential candidate processes to a select group of eight processes. The critical technologies that would be required for these routes were: (1) the esterification of acetaldehyde (AcH) with ketene to generate VAM, (2) the hydrogenation of ketene to acetaldehyde, (3) the hydrogenation of acetic acid to acetaldehyde, and (4) the reductive carbonylation of methanol to acetaldehyde. This report describes the selection process for the candidate processes, the successful development of the key technologies, and the economic assessments for the preferred routes. In addition, improvements in the conversion of acetic anhydride and acetaldehyde to VAM are discussed. The conclusion from this study is that, with the technology developed in this study, VAM may be produced from synthesis gas, but the cost of production is about 15% higher than the conventional oxidative acetoxylation of ethylene, primarily due to higher capital associated with the synthesis gas-based processes.

  19. Chemical synthesis of a dual branched malto-decaose: A potential substrate for alpha-amylases

    DEFF Research Database (Denmark)

    Damager, Iben; Jensen, Morten; Olsen, Carl Erik

    2005-01-01

    A convergent block strategy for general use in efficient synthesis of complex alpha-(1 -> 4)- and alpha-(1 -> 6)-malto-oligosaccharides is demonstrated with the first chemical synthesis of a malto-oligosaccharide, the decasoccharide 6,6""-bis(alpha-maltosyl)-maltohexaose, with two branch points....... Using this chemically defined branched oligosaccharide as a substrate, the cleavage pattern of seven different alpha-amylases were investigated. alpha-Amylases from human saliva, porcine pancreas, barley alpha-amylose 2 and recombinant barley alpha-amylase 1 all hydrolysed the decasaccharide selectively....... This resulted in a branched hexasaccharide and a branched tetrasoccharide. alpha-Amylases from Asperagillus oryzae, Bacillus licheniformis and Bacillus sp. cleaved the decasoccharide at two distinct sites, either producing two branched pentasoccharides, or a branched hexasoccharide and a branched...

  20. The impact of the chemical synthesis on the magnetic properties of intermetallic PdFe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos-Rubio, I.; Insausti, M.; Muro, I. Gil de [Universidad del País Vasco, UPV/EHU, Dpto. de Química Inorgánica (Spain); Arias-Duque, D. Carolina; Hernández-Garrido, Juan Carlos [Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias (Spain); Rojo, T.; Lezama, L., E-mail: luis.lezama@ehu.es [Universidad del País Vasco, UPV/EHU, Dpto. de Química Inorgánica (Spain)

    2015-05-15

    Palladium-rich Iron nanoparticles in the 4–8 nm range have been produced by a combination of two methods: the thermal decomposition of organometallic precursors and the reduction of metallic salts by a polyol. Herein, it is shown how the details of the synthesis have a striking impact on the magnetic and morphological properties of the final products. In the synthesis of these bimetallic nanoparticles, the use of high reaction temperatures plays an essential role in attaining good chemical homogeneity, which has proved to have a key influence on the magnetic properties. Magnetic characterization has been performed by electron magnetic resonance and magnetization measurements, which have confirmed the superparamagnetic-like behavior at room temperature. No clear traces of magnetic polarization in palladium atoms have been detected. The combination of long-term stability and homogeneous chemical and magnetic properties makes these particles very suitable for a wide range of applications in nanotechnology.

  1. The impact of the chemical synthesis on the magnetic properties of intermetallic PdFe nanoparticles

    International Nuclear Information System (INIS)

    Castellanos-Rubio, I.; Insausti, M.; Muro, I. Gil de; Arias-Duque, D. Carolina; Hernández-Garrido, Juan Carlos; Rojo, T.; Lezama, L.

    2015-01-01

    Palladium-rich Iron nanoparticles in the 4–8 nm range have been produced by a combination of two methods: the thermal decomposition of organometallic precursors and the reduction of metallic salts by a polyol. Herein, it is shown how the details of the synthesis have a striking impact on the magnetic and morphological properties of the final products. In the synthesis of these bimetallic nanoparticles, the use of high reaction temperatures plays an essential role in attaining good chemical homogeneity, which has proved to have a key influence on the magnetic properties. Magnetic characterization has been performed by electron magnetic resonance and magnetization measurements, which have confirmed the superparamagnetic-like behavior at room temperature. No clear traces of magnetic polarization in palladium atoms have been detected. The combination of long-term stability and homogeneous chemical and magnetic properties makes these particles very suitable for a wide range of applications in nanotechnology

  2. Some chemical synthesis of 14C labelled compounds of pharmaceutical or biological interest

    International Nuclear Information System (INIS)

    Pichat, I.; Baret, C.; Audinot, M.; Herbert, M.; Lambin, J.

    1955-01-01

    The recent discovery of the tuberculostatic properties of the hydrazide of isonicotinic acid (so-called 'Isoniazide', 'Rimifon') has raised considerably its interest, as for metabolic studies which it is more interesting to have it labelled with 14 C. We describe in this report the chemical synthesis of 14 C carboxyl labelled isoniazide which were done in the pyridine ring to highlight his metabolic function on the Koch's bacillus. (M.B.)

  3. Some chemical synthesis of {sup 14}C labelled compounds of pharmaceutical or biological interest

    Energy Technology Data Exchange (ETDEWEB)

    Pichat, I; Baret, C; Audinot, M; Herbert, M; Lambin, J [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1955-07-01

    The recent discovery of the tuberculostatic properties of the hydrazide of isonicotinic acid (so-called 'Isoniazide', 'Rimifon') has raised considerably its interest, as for metabolic studies which it is more interesting to have it labelled with {sup 14}C. We describe in this report the chemical synthesis of {sup 14}C carboxyl labelled isoniazide which were done in the pyridine ring to highlight his metabolic function on the Koch's bacillus. (M.B.)

  4. Recent Progress in the Chemical Synthesis of Class II and S-Glycosylated Bacteriocins

    Directory of Open Access Journals (Sweden)

    François Bédard

    2018-05-01

    Full Text Available A wide variety of antimicrobial peptides produced by lactic acid bacteria (LAB have been identified and studied in the last decades. Known as bacteriocins, these ribosomally synthesized peptides inhibit the growth of a wide range of bacterial species through numerous mechanisms and show a great variety of spectrum of activity. With their great potential as antimicrobial additives and alternatives to traditional antibiotics in food preservation and handling, animal production and in veterinary and medical medicine, the demand for bacteriocins is rapidly increasing. Bacteriocins are most often produced by fermentation but, in several cases, the low isolated yields and difficulties associated with their purification seriously limit their use on a large scale. Chemical synthesis has been proposed for their production and recent advances in peptide synthesis methodologies have allowed the preparation of several bacteriocins. Moreover, the significant cost reduction for peptide synthesis reagents and building blocks has made chemical synthesis of bacteriocins more attractive and competitive. From a protein engineering point of view, the chemical approach offers many advantages such as the possibility to rapidly perform amino acid substitution, use unnatural or modified residues, and make backbone and side chain modifications to improve potency, modify the activity spectrum or increase the stability of the targeted bacteriocin. This review summarized synthetic approaches that have been developed and used in recent years to allow the preparation of class IIa bacteriocins and S-linked glycopeptides from LAB. Synthetic strategies such as the use of pseudoprolines, backbone protecting groups, microwave irradiations, selective disulfide bridge formation and chemical ligations to prepare class II and S-glycosylsated bacteriocins are discussed.

  5. Synthesis of Molecularly Imprinted Polymer for Sterol Separation

    Directory of Open Access Journals (Sweden)

    Yuangsawad Ratanaporn

    2016-01-01

    Full Text Available Molecular imprinted polymer (MIP was prepared by bulk polymerization in acetone using acrylamide as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, stigmasterol as a template and benzoyl peroxide as an initiator. The obtained MIPs were characterized using a scanning electron microscope and a fourier transform infrared spectrophotometer. Performance in sterol adsorption of MIPs prepared under various conditions was investigated using a model solution of phytosterols in heptane, comparing with a nonimprinted polymer (NIP. Statistical analysis revealed that the amounts of crosslinker and template strongly affected the performance of MIP while the amount of solvent slightly affected the performance of MIP. MIP synthesized under the optimal condition had adsorption capacity of 1.28 mgsterols/gads which were 1.13 times of NIP.

  6. Chemical synthesis of Cd-free wide band gap materials for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R.; Sartale, S.D.; Ennaoui, A. [Hahn-Meitner-Institut, Berlin (Germany). Department of Solar Energy Research; Lokhande, C.D. [Shivaji University, Kolhapur (India). Department of Physics

    2004-07-01

    Chemical methods are nowadays very attractive, since they are relatively simple, low cost and convenient for larger area deposition of thin films. In this paper, we outline our work related to the synthesis and characterization of some wide band gap semiconducting material thin films prepared by using solution methods, namely, chemical bath deposition and successive ionic layer adsorption and reaction (SILAR). The optimum preparative parameters are given and respective structural, surface morphological, compositional, optical, and electrical properties are described. Some materials we used in solar cells as buffer layers and achieved remarkable results, which are summarized. (author)

  7. Hydro-chemical study of the evolution of interstellar pre-biotic molecules during the collapse of molecular clouds

    International Nuclear Information System (INIS)

    Majumdar, Liton; Das, Ankan; Chakrabarti, Sandip K.; Chakrabarti, Sonali

    2012-01-01

    One of the stumbling blocks for studying the evolution of interstellar molecules is the lack of adequate knowledge about the rate coefficients of various reactions which take place in the interstellar medium and molecular clouds. Some theoretical models of rate coefficients do exist in the literature for computing abundances of complex pre-biotic molecules. So far these have been used to study the abundances of these molecules in space. However, in order to obtain more accurate final compositions in these media, we have calculated the rate coefficients for the formation of some of the most important interstellar pre-biotic molecules by using quantum chemical theory. We use these rates inside our hydro-chemical model to examine the chemical evolution and final abundances of pre-biotic species during the collapsing phase of a proto-star. We find that a significant amount of various pre-biotic molecules could be produced during the collapse phase of a proto-star. We thoroughly study the formation of these molecules via successive neutral-neutral and radical-radical/radical-molecular reactions. We present the time evolution of the chemical species with an emphasis on how the production of these molecules varies with the depth of a cloud. We compare the formation of adenine in interstellar space using our rate-coefficients and using those obtained from existing theoretical models. Formation routes of the pre-biotic molecules are found to be highly dependent on the abundances of the reactive species and the rate coefficients involved in the reactions. The presence of grains strongly affects the abundances of the gas phase species. We also carry out a comparative study between different pathways available for the synthesis of adenine, alanine, glycine and other molecules considered in our network. Despite the huge abundances of the neutral reactive species, production of adenine is found to be strongly dominated by the radical-radical/radical-molecular reaction pathways

  8. Chemical synthesis, phase transformation and magnetic proprieties of FePt and FePd nanoparticles

    International Nuclear Information System (INIS)

    Delattre, Anastasia

    2010-01-01

    This work aims at understanding the chemical synthesis of FePt and FePd nanoparticles (NPs), and at exploring how to implement the phase transformation from the chemically disordered to the L10 phase, without coalescence. Using hexadecanenitrile instead of oleylamine, we obtain NPs with a more homogenous internal composition, instead of core-shell NPs. Through a systematic study (designed experiment relying on Taguchi tables), we developed the FePd synthesis, while evidencing the role of each ligand and of the reductor. To induce the crystalline phase transformation while avoiding coalescence, we explored two ways. In the first one, atomic vacancies are introduced in the NPs through light ion irradiation, atomic mobility being ensured by annealing at moderate temperature (300 C). As a result, the blocking temperature is multiplied by 4, due to anisotropy enhancement. However, strong chemical ordering in the L10 phase cannot be achieved. The second approach relies on the dispersion of the NPs in a salt (NaCl) matrix, prior to annealing at 700 C: high chemical ordering is achieved, and the blocking temperature is beyond 400 C. We then developed a single-step process to remove the salt by dissolution in water and to re-disperse NPs in stable aqueous or organics solutions. These high magnetic anisotropy NPs are then readily available for further chemical or manipulation steps, with applied perspectives in areas such as data storage, or biology. (author)

  9. Molecular structure design and soft template synthesis of aza-, oxaaza- and thiaazamacrocyclic metal chelates in the gelatin matrix

    OpenAIRE

    Oleg V. Mikhailov

    2017-01-01

    The data about of soft template synthesis proceeding in gelatin matrices in [3d-element M(II) ion – (N,S)- or (N,O,S)-ambidentate ligson – mono- or dicarbonyl ligson] systems, have been considered and discussed. The chemical nature of the final products of template synthesis formed under these specific conditions, has been compared with the chemical nature of the final products formed by template synthesis in solutions. It has been noted that in many cases, the nature and chemical composition...

  10. Reducing aquatic hazards of industrial chemicals: probabilistic assessment of sustainable molecular design guidelines.

    Science.gov (United States)

    Connors, Kristin A; Voutchkova-Kostal, Adelina M; Kostal, Jakub; Anastas, Paul; Zimmerman, Julie B; Brooks, Bryan W

    2014-08-01

    Basic toxicological information is lacking for the majority of industrial chemicals. In addition to increasing empirical toxicity data through additional testing, prospective computational approaches to drug development aim to serve as a rational basis for the design of chemicals with reduced toxicity. Recent work has resulted in the derivation of a "rule of 2," wherein chemicals with an octanol-water partition coefficient (log P) less than 2 and a difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital (ΔE) greater than 9 (log P9 eV) are predicted to be 4 to 5 times less likely to elicit acute or chronic toxicity to model aquatic organisms. The present study examines potential reduction of aquatic toxicity hazards from industrial chemicals if these 2 molecular design guidelines were employed. Probabilistic hazard assessment approaches were used to model the likelihood of encountering industrial chemicals exceeding toxicological categories of concern both with and without the rule of 2. Modeling predicted that utilization of these molecular design guidelines for log P and ΔE would appreciably decrease the number of chemicals that would be designated to be of "high" and "very high" concern for acute and chronic toxicity to standard model aquatic organisms and end points as defined by the US Environmental Protection Agency. For example, 14.5% of chemicals were categorized as having high and very high acute toxicity to the fathead minnow model, whereas only 3.3% of chemicals conforming to the design guidelines were predicted to be in these categories. Considerations of specific chemical classes (e.g., aldehydes), chemical attributes (e.g., ionization), and adverse outcome pathways in representative species (e.g., receptor-mediated responses) could be used to derive future property guidelines for broader classes of contaminants. © 2014 SETAC.

  11. Molecular epidemiology of childhood leukemia with emphasis on chemical exposures

    Energy Technology Data Exchange (ETDEWEB)

    Buffler, P.A.; Smith, M.T.; Wood, S. [Univ. of California, Berkeley, CA (United States); Reynolds, P. [California Dept. of Health Services, Emeryville, CA (United States)

    1996-12-31

    Developing markets in the Pacific Basin depend heavily on the production and export of consumer goods. The generation of hazardous waste as a by-product of industrial production can be linked to adverse health outcomes, such as childhood leukemia, in ways that are presently unknown. In California, exposures resulting from hazardous waste disposal are of concern in the etiology of childhood cancer. Approximately 63% of the 57 hazardous waste sites that the U.S. Environmental Protection Agency (USEPA) included in the national priority list under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) statute were in the six-county San Francisco Bay area. This area includes California`s Silicon Valley, where a disproportionate majority of these sites are located. Although only one study links hazardous waste disposal to childhood leukemia evidence is accumulating that in utero and maternal pesticide exposures as well as chemical exposures during childhood are important in the etiology of childhood leukemia. This study investigates whether children with leukemia have common genetic changes, whether children with genetic changes experience common chemical exposures, and whether the occurrences of these genetic changes correspond to the same temporal sequence as exposure. The purpose of this paper is to describe the study design and report on the status of research activity. 10 refs., 1 fig., 3 tabs.

  12. Synthesis and Characterization of a Magnetically Active 19F Molecular Beacon.

    Science.gov (United States)

    Dempsey, Megan E; Marble, Hetal D; Shen, Tun-Li; Fawzi, Nicolas L; Darling, Eric M

    2018-02-21

    Gene expression is used extensively to describe cellular characteristics and behaviors; however, most methods of assessing gene expression are unsuitable for living samples, requiring destructive processes such as fixation or lysis. Recently, molecular beacons have become a viable tool for live-cell imaging of mRNA molecules in situ. Historically, beacon-mediated imaging has been limited to fluorescence-based approaches. We propose the design and synthesis of a novel molecular beacon for magnetic resonance detection of any desired target nucleotide sequence. The biologically compatible synthesis incorporates commonly used bioconjugation reactions in aqueous conditions and is accessible for laboratories without extensive synthesis capabilities. The resulting beacon uses fluorine ( 19 F) as a reporter, which is broadened, or turned "off", via paramagnetic relaxation enhancement from a stabilized nitroxide radical spin label when the beacon is not bound to its nucleic acid target. Therefore, the 19 F NMR signal of the beacon is quenched in its hairpin conformation when the spin label and the 19 F substituent are held in proximity, but the signal is recovered upon beacon hybridization to its specific complementary nucleotide sequence by physical separation of the radical from the 19 F reporter. This study establishes a path for magnetic resonance-based assessment of specific mRNA expression, providing new possibilities for applying molecular beacon technology in living systems.

  13. RPMDrate: Bimolecular chemical reaction rates from ring polymer molecular dynamics

    KAUST Repository

    Suleimanov, Yu.V.

    2013-03-01

    We present RPMDrate, a computer program for the calculation of gas phase bimolecular reaction rate coefficients using the ring polymer molecular dynamics (RPMD) method. The RPMD rate coefficient is calculated using the Bennett-Chandler method as a product of a static (centroid density quantum transition state theory (QTST) rate) and a dynamic (ring polymer transmission coefficient) factor. The computational procedure is general and can be used to treat bimolecular polyatomic reactions of any complexity in their full dimensionality. The program has been tested for the H+H2, H+CH 4, OH+CH4 and H+C2H6 reactions. © 2012 Elsevier B.V. All rights reserved.

  14. Molecular relics from chemical evolution and the origin of life

    International Nuclear Information System (INIS)

    Chela Flores, J.

    1994-04-01

    The main hypothesis proposed in this work intends to remove the difficulty that arises from the conjecture that the RNA world may have left molecular relics that may still be extant in the angiosperms. We discuss whether it is possible to envisage a possible evolutionary pathway of the RNA replicators spanning the vast time span separating the first appearance of the angiosperms, late in the Mesozoic era (the Lower Cretaceous), from the most likely suberas in which the RNA world may have occurred, namely the Hadean/Early Archean. In order to address this question we suggest that through horizontal gene transfer, as well as through a series of symbiosis of the precursor cell of the land plants, the genes of the replicases (RNA-directed RNA polymerases) associated with putative DNA-independent RNA replicators may have been transferred vertically, eventually becoming specific to the angiosperms. (author). Refs, 7 tabs

  15. RPMDrate: Bimolecular chemical reaction rates from ring polymer molecular dynamics

    KAUST Repository

    Suleimanov, Yu.V.; Allen, J.W.; Green, W.H.

    2013-01-01

    We present RPMDrate, a computer program for the calculation of gas phase bimolecular reaction rate coefficients using the ring polymer molecular dynamics (RPMD) method. The RPMD rate coefficient is calculated using the Bennett-Chandler method as a product of a static (centroid density quantum transition state theory (QTST) rate) and a dynamic (ring polymer transmission coefficient) factor. The computational procedure is general and can be used to treat bimolecular polyatomic reactions of any complexity in their full dimensionality. The program has been tested for the H+H2, H+CH 4, OH+CH4 and H+C2H6 reactions. © 2012 Elsevier B.V. All rights reserved.

  16. Final Technical Report for SISGR: Ultrafast Molecular Scale Chemical Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hersam, Mark C. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Guest, Jeffrey R. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Guisinger, Nathan P. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Hla, Saw Wai [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Schatz, George C. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Seideman, Tamar [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Van Duyne, Richard P. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

    2017-04-10

    The Northwestern-Argonne SISGR program utilized newly developed instrumentation and techniques including integrated ultra-high vacuum tip-enhanced Raman spectroscopy/scanning tunneling microscopy (UHV-TERS/STM) and surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS) to advance the spatial and temporal resolution of chemical imaging for the study of photoinduced dynamics of molecules on plasmonically active surfaces. An accompanying theory program addressed modeling of charge transfer processes using constrained density functional theory (DFT) in addition to modeling of SE-FSRS, thereby providing a detailed description of the excited state dynamics. This interdisciplinary and highly collaborative research resulted in 62 publications with ~ 48% of them being co-authored by multiple SISGR team members. A summary of the scientific accomplishments from this SISGR program is provided in this final technical report.

  17. Chemical and molecular factors in irritable bowel syndrome: current knowledge, challenges, and unanswered questions.

    Science.gov (United States)

    Camilleri, Michael; Oduyebo, Ibironke; Halawi, Houssam

    2016-11-01

    Several chemical and molecular factors in the intestine are reported to be altered and to have a potentially significant role in irritable bowel syndrome (IBS), particularly in IBS with diarrhea. These include bile acids; short-chain fatty acids; mucosal barrier proteins; mast cell products such as histamine, proteases, and tryptase; enteroendocrine cell products; and mucosal mRNAs, proteins, and microRNAs. This article reviews the current knowledge and unanswered questions in the pathobiology of the chemical and molecular factors in IBS. Evidence continues to point to significant roles in pathogenesis of these chemical and molecular mechanisms, which may therefore constitute potential targets for future research and therapy. However, it is still necessary to address the interaction between these factors in the gut and to appraise how they may influence hypervigilance in the central nervous system in patients with IBS. Copyright © 2016 the American Physiological Society.

  18. Efficient and Scalable Synthesis of 4-Carboxy-Pennsylvania Green Methyl Ester: A Hydrophobic Building Block for Fluorescent Molecular Probes.

    Science.gov (United States)

    Woydziak, Zachary R; Fu, Liqiang; Peterson, Blake R

    2014-01-01

    Fluorinated fluorophores are valuable tools for studies of biological systems. However, amine-reactive single-isomer derivatives of these compounds are often very expensive. To provide an inexpensive alternative, we report a practical synthesis of 4-carboxy-Pennsylvania Green methyl ester. Derivatives of this hydrophobic fluorinated fluorophore, a hybrid of the dyes Oregon Green and Tokyo Green, are often cell permeable, enabling labeling of intracellular targets and components. Moreover, the low pKa of Pennsylvania Green (4.8) confers bright fluorescence in acidic cellular compartments such as endosomes, enhancing its utility for chemical biology investigations. To improve access to the key intermediate 2,7-difluoro-3,6-dihydroxyxanthen-9-one, we subjected bis-(2,4,5-trifluorophenyl)methanone to iterative nucleophilic aromatic substitution by hydroxide on scales of > 40 g. This intermediate was used to prepare over 15 grams of pure 4-carboxy-Pennsylvania Green methyl ester in 28% overall yield without requiring chromatography. This compound can be converted into the amine reactive N -hydroxysuccinimidyl ester in essentially quantitative yield for the synthesis of a wide variety of fluorescent molecular probes.

  19. Pumping requirements and options for molecular beam epitaxy and gas source molecular beam epitaxy/chemical beam epitaxy

    International Nuclear Information System (INIS)

    McCollum, M.J.; Plano, M.A.; Haase, M.A.; Robbins, V.M.; Jackson, S.L.; Cheng, K.Y.; Stillman, G.E.

    1989-01-01

    This paper discusses the use of gas sources in growth by MBE as a result of current interest in growth of InP/InGaAsP/InGaAs lattice matched to InP. For gas flows greater than a few sccm, pumping speed requirements dictate the use of turbomolecular or diffusion pumps. GaAs samples with high p-type mobilities have been grown with diffusion pumped molecular beam epitaxial system. According to the authors, this demonstration of the inherent cleanliness of a properly designed diffusion pumping system indicates that a diffusion pump is an excellent inexpensive and reliable choice for growth by molecular beam epitaxy and gas source molecular beam epitaxy/chemical beam epitaxy

  20. Synthesis and reforming of high molecular-weigth compounds by the utilization of radiation

    International Nuclear Information System (INIS)

    Machi, Sueo

    1976-01-01

    Radiation effects on the synthesis are reforming of high molecular-weight compounds are reviewed. The report is divided into four main parts. The first part deals with the characteristics of the radiation processing. The reaction can be started in a wide range of temperature including very low temperature. Catalysts are unnecessary. The reaction velocity is fast, and the reaction in solid phase can be started uniformly. And the quality of products is well controllable. The second part deals with the synthesis of high molecular-weight compounds by radiation polymerization. Radical polymerization and ionizing polymerization, gas phase and liquid phase polymerization, the polymerization and copolymerization of fluorine-containing monomers, and solid phase polymerization and low temperature polymerization are included in this part. Attention is directed to the continuous production system for the radiation polymerization of ethylene developed by Japan Atomic Energy Research Institute. The third part deals with the reforming of high molecular-weight compounds by radiation graft polymerization. The combination of backbone polymers and monomers for reforming plastics and fibers, the membranes for reverse osmosis, porous membranes, and ion exchange membranes are included. The fourth part deals with the reforming of high molecular-weight compounds by the cross-linking. Polyethylene, PVC, ethyl acrylate copolymer and the like are included. (Iwakiri, K.)

  1. All-organic microelectromechanical systems integrating specific molecular recognition--a new generation of chemical sensors.

    Science.gov (United States)

    Ayela, Cédric; Dubourg, Georges; Pellet, Claude; Haupt, Karsten

    2014-09-03

    Cantilever-type all-organic microelectromechanical systems based on molecularly imprinted polymers for specific analyte recognition are used as chemical sensors. They are produced by a simple spray-coating-shadow-masking process. Analyte binding to the cantilever generates a measurable change in its resonance frequency. This allows label-free detection by direct mass sensing of low-molecular-weight analytes at nanomolar concentrations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Radiation-chemical yields of molecular hydrogen formation in cyclohexane based alcohols

    International Nuclear Information System (INIS)

    Val'ter, A.I.; Kovalev, G.V.

    1988-01-01

    Molecular hydrogen radiation-chemical yields in γ-irradiated cyclohexanol, 1.2-cis- and 1.2-trans-cyclohexandiols and inositol are determined within the general problem frameworks of radiolysis mechanism for cyclohexanering-base alcohols. Irradiation was conducted at 77 and 293 K, dose rate - 4 Gy/s. Hydrogen concentration in all irradiated alcohols depends linearly on the dose. Radiation-chemical yields of H 2 and of stabilized radicals, as well, in the irradiated crystalline alcohols are analyzed depending on the irradiation temperature, alcohol molecular structure

  3. Titanium nitride plasma-chemical synthesis with titanium tetrachloride raw material in the DC plasma-arc reactor

    Science.gov (United States)

    Kirpichev, D. E.; Sinaiskiy, M. A.; Samokhin, A. V.; Alexeev, N. V.

    2017-04-01

    The possibility of plasmochemical synthesis of titanium nitride is demonstrated in the paper. Results of the thermodynamic analysis of TiCl4 - H2 - N2 system are presented; key parameters of TiN synthesis process are calculated. The influence of parameters of plasma-chemical titanium nitride synthesis process in the reactor with an arc plasmatron on characteristics on the produced powders is experimentally investigated. Structure, chemical composition and morphology dependencies on plasma jet enthalpy, stoichiometric excess of hydrogen and nitrogen in a plasma jet are determined.

  4. Chemical synthesis of perfectly isotactic and high melting bacterial poly(3-hydroxybutyrate) from bio-sourced racemic cyclic diolide.

    Science.gov (United States)

    Tang, Xiaoyan; Chen, Eugene Y-X

    2018-06-11

    Bacterial poly(3-hydroxybutyrate) (P3HB) is a perfectly isotactic, crystalline material possessing properties suitable for substituting petroleum plastics, but high costs and low volumes of its production are impractical for commodity applications. The chemical synthesis of P3HB via ring-opening polymerization (ROP) of racemic β-butyrolactone has attracted intensive efforts since the 1960s, but not yet produced P3HB with high isotacticity and molecular weight. Here, we report a route utilizing racemic cyclic diolide (rac-DL) derived from bio-sourced succinate. With stereoselective racemic catalysts, the ROP of rac-DL under ambient conditions produces rapidly P3HB with perfect isotacticity ([mm] > 99%), high melting temperature (T m  = 171 °C), and high molecular weight (M n  = 1.54 × 10 5  g mol -1 , Đ = 1.01). With enantiomeric catalysts, kinetic resolution polymerizations of rac-DL automatically stops at 50% conversion and yields enantiopure (R,R)-DL and (S,S)-DL with >99% e.e. and the corresponding poly[(S)-3HB] and poly[(R)-3HB] with high T m  = 175 °C.

  5. Equilibrium simulations of proteins using molecular fragment replacement and NMR chemical shifts.

    Science.gov (United States)

    Boomsma, Wouter; Tian, Pengfei; Frellsen, Jes; Ferkinghoff-Borg, Jesper; Hamelryck, Thomas; Lindorff-Larsen, Kresten; Vendruscolo, Michele

    2014-09-23

    Methods of protein structure determination based on NMR chemical shifts are becoming increasingly common. The most widely used approaches adopt the molecular fragment replacement strategy, in which structural fragments are repeatedly reassembled into different complete conformations in molecular simulations. Although these approaches are effective in generating individual structures consistent with the chemical shift data, they do not enable the sampling of the conformational space of proteins with correct statistical weights. Here, we present a method of molecular fragment replacement that makes it possible to perform equilibrium simulations of proteins, and hence to determine their free energy landscapes. This strategy is based on the encoding of the chemical shift information in a probabilistic model in Markov chain Monte Carlo simulations. First, we demonstrate that with this approach it is possible to fold proteins to their native states starting from extended structures. Second, we show that the method satisfies the detailed balance condition and hence it can be used to carry out an equilibrium sampling from the Boltzmann distribution corresponding to the force field used in the simulations. Third, by comparing the results of simulations carried out with and without chemical shift restraints we describe quantitatively the effects that these restraints have on the free energy landscapes of proteins. Taken together, these results demonstrate that the molecular fragment replacement strategy can be used in combination with chemical shift information to characterize not only the native structures of proteins but also their conformational fluctuations.

  6. Room temperature chemical synthesis of Cu(OH){sub 2} thin films for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Gurav, K.V. [Thin Film Photonic and Electronics Lab, Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of); Patil, U.M. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416 007 (M.S.) (India); Shin, S.W.; Agawane, G.L.; Suryawanshi, M.P.; Pawar, S.M.; Patil, P.S. [Thin Film Photonic and Electronics Lab, Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of); Lokhande, C.D. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416 007 (M.S.) (India); Kim, J.H., E-mail: jinhyeok@chonnam.ac.kr [Thin Film Photonic and Electronics Lab, Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of)

    2013-10-05

    Highlights: •Cu(OH){sub 2} is presented as the new supercapacitive material. •The novel room temperature method used for the synthesis of Cu(OH){sub 2}. •The hydrous, nanograined Cu(OH){sub 2} shows higher specific capacitance of 120 F/g. -- Abstract: Room temperature soft chemical synthesis route is used to grow nanograined copper hydroxide [Cu(OH){sub 2}] thin films on glass and stainless steel substrates. The structural, morphological, optical and wettability properties of Cu(OH){sub 2} thin films are studied by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV–vis spectrophotometer and water contact angle measurement techniques. The results showed that, room temperature chemical synthesis route allows to form the nanograined and hydrophilic Cu(OH){sub 2} thin films with optical band gap energy of 3.0 eV. The electrochemical properties of Cu(OH){sub 2} thin films are studied in an aqueous 1 M NaOH electrolyte using cyclic voltammetry. The sample exhibited supercapacitive behavior with 120 F/g specific capacitance.

  7. Room temperature chemical synthesis of Cu(OH)2 thin films for supercapacitor application

    International Nuclear Information System (INIS)

    Gurav, K.V.; Patil, U.M.; Shin, S.W.; Agawane, G.L.; Suryawanshi, M.P.; Pawar, S.M.; Patil, P.S.; Lokhande, C.D.; Kim, J.H.

    2013-01-01

    Highlights: •Cu(OH) 2 is presented as the new supercapacitive material. •The novel room temperature method used for the synthesis of Cu(OH) 2 . •The hydrous, nanograined Cu(OH) 2 shows higher specific capacitance of 120 F/g. -- Abstract: Room temperature soft chemical synthesis route is used to grow nanograined copper hydroxide [Cu(OH) 2 ] thin films on glass and stainless steel substrates. The structural, morphological, optical and wettability properties of Cu(OH) 2 thin films are studied by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV–vis spectrophotometer and water contact angle measurement techniques. The results showed that, room temperature chemical synthesis route allows to form the nanograined and hydrophilic Cu(OH) 2 thin films with optical band gap energy of 3.0 eV. The electrochemical properties of Cu(OH) 2 thin films are studied in an aqueous 1 M NaOH electrolyte using cyclic voltammetry. The sample exhibited supercapacitive behavior with 120 F/g specific capacitance

  8. Synthesis of ultra-long cadmium telluride nanotubes via combinational chemical transformation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kee-Ryung; Cho, Hong-Baek; Choa, Yong-Ho, E-mail: choa15@hanyang.ac.kr

    2017-03-01

    Synthesis of high-throughput cadmium telluride (CdTe) nanotubes with an ultra-long aspect ratio is presented via a combination process concept combined with electrospinning, electrodeposition, and cationic exchange reaction. Ultra-long sacrificial silver (Ag) nanofibers were synthesized by electrospinning involving two-step calcination, and were then electrodeposited to create silver telluride nanotubes. These nanotubes underwent cationic exchange reaction in cadmium nitrate tetrahydrate solution with the aid of a ligand, tributylphosphine (TBP). Analysis showed that ultra-long pure zinc blende CdTe nanotubes were obtained with controlled dimension and uniform morphology. The thermodynamic driving force induced by the coordination of methanol solvent and TBP attributed to overcome the kinetic barrier between Ag{sub 2}Te and CdTe nanotubes, facilitating the synthesis of CdTe nanotubes. This synthetic process involving a topotactic reaction route paves a way for high-throughput extended synthesis of new chalcogenide hollow nanotubes for application in photodetectors and solar cells. - Highlights: • High throughput synthetic route of hollow CdTe nanotubes with ultra-long aspect ratio. • Chemical combination of electrospinning, electrodeposition & cation exchange reaction. • Pure zinc blende CdTe by controlled dimension & structural variation of Ag nanofibers. • Potential for the high throughput synthesis of new exotic chalcogenide nanotubes.

  9. Chemical and mechanical efficiencies of molecular motors and implications for motor mechanisms

    International Nuclear Information System (INIS)

    Wang Hongyun

    2005-01-01

    Molecular motors operate in an environment dominated by viscous friction and thermal fluctuations. The chemical reaction in a motor may produce an active force at the reaction site to directly move the motor forward. Alternatively a molecular motor may generate a unidirectional motion by rectifying thermal fluctuations using free energy barriers established in the chemical reaction. The reaction cycle has many occupancy states, each having a different effect on the motor motion. The average effect of the chemical reaction on the motor motion can be characterized by the motor potential profile. The biggest advantage of studying the motor potential profile is that it can be reconstructed from the time series of motor positions measured in single-molecule experiments. In this paper, we use the motor potential profile to express the Stokes efficiency as the product of the chemical efficiency and the mechanical efficiency. We show that both the chemical and mechanical efficiencies are bounded by 100% and, thus, are properly defined efficiencies. We discuss implications of high efficiencies for motor mechanisms: a mechanical efficiency close to 100% implies that the motor potential profile is close to a constant slope; a chemical efficiency close to 100% implies that (i) the chemical transitions are not slower than the mechanical motion and (ii) the equilibrium constant of each chemical transition is close to one

  10. Synthesis and Studies of Sulfur-Containing Heterocyclic Molecules for Molecular Electronics

    DEFF Research Database (Denmark)

    Mazzanti, Virginia

    This work describes the synthesis and studies of sulfur containing π conjugated heterocycles, which are considered interesting motifs in the field of molecular electronics. The first project, which is covered in Chapter 1, concerns the functionalization of tetracycle dibenzo[bc,fg][1,4]dithiapent......This work describes the synthesis and studies of sulfur containing π conjugated heterocycles, which are considered interesting motifs in the field of molecular electronics. The first project, which is covered in Chapter 1, concerns the functionalization of tetracycle dibenzo[bc,fg][1......,4]dithiapentalene (DDP). Attempts to prepare the S-O analog are also discussed. Chapter 2, focuses upon the studies performed on DDP and other sulfur containing π conjugated organic molecules. Organic Field Effect Transistor devices were fabricated and their performances were evaluated. Chapter 3 entails...... the synthesis of dimeric structures of redox active system tetrathiafulvalene (TTF). Molecules with different conjugation pathways bridging two TTFs were synthesized and studied using CV and DPV in order to probe the electronic interaction between these two redox units. The last aspect of this thesis, which...

  11. CdS nanowires formed by chemical synthesis using conjugated single-stranded DNA molecules

    Science.gov (United States)

    Sarangi, S. N.; Sahu, S. N.; Nozaki, S.

    2018-03-01

    CdS nanowires were successfully grown by chemical synthesis using two conjugated single-stranded (ss) DNA molecules, poly G (30) and poly C (30), as templates. During the early stage of the synthesis with the DNA molecules, the Cd 2+ interacts with Poly G and Poly C and produces the (Cd 2+)-Poly GC complex. As the growth proceeds, it results in nanowires. The structural analysis by grazing angle x-ray diffraction and transmission electron microscopy confirmed the zinc-blende CdS nanowires with the growth direction of . Although the nanowires are well surface-passivated with the DNA molecules, the photoluminescence quenching was caused by the electron transfer from the nanowires to the DNA molecules. The quenching can be used to detect and label the DNAs.

  12. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-01-01

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 deg. C down to 450 deg. C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 Ω/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  13. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    Science.gov (United States)

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-06-01

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 °C down to 450 °C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 Ω/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  14. Synthesis of Y-Tip Graphitic Nanoribbons from Alcohol Catalytic Chemical Vapor Deposition on Piezoelectric Substrate

    Directory of Open Access Journals (Sweden)

    Zainab Yunusa

    2015-01-01

    Full Text Available We report the synthesis of Graphitic Nanoribbons (GNRs using Alcohol Catalytic Chemical Vapor Deposition (ACCVD. Bulk GNR was synthesized directly on a piezoelectric substrate using one-step ACCVD. The synthesized GNRs were characterized by X-Ray Diffraction (XRD, Scanning Electron Microscope (SEM, Transmission Electron Microscope (TEM, Energy Dispersive X-Ray (EDX, Atomic Force Microscopy (AFM, and Raman spectroscopy. The characterization results showed Y-tip morphology of bulk and filamentous as-grown GNR having varying width that lies between tens and hundreds of nm and length of several microns. Based on the thickness obtained from the AFM and the analysis from the Raman spectroscopy, it was concluded that the synthesized GNRs are multiple-layered and graphitic in nature. With the direct synthesis of GNR on a piezoelectric substrate, it could have applications in the sensor industries, while the Y-tip GNR could have potentialities in semiconductor applications.

  15. Macrokinetics of carbon nanotubes synthesis by the chemical vapor deposition method

    Science.gov (United States)

    Rukhov, Artem; Dyachkova, Tatyana; Tugolukov, Evgeny; Besperstova, Galina

    2017-11-01

    A new approach to studying and developing basic processes which take place on the surface of a metal catalyst during the thermal decomposition of carbonaceous substances in the carbon nanotubes synthesis by the chemical vapor deposition method was proposed. In addition, an analysis was made of the interrelationships between these thermal, diffusion, hydrodynamic and other synthesis processes. A strong effect of the catalyst regeneration stage on the stage of nanotube formation has been shown. Based on the developed approach, a mathematical model was elaborated. Comparison of the calculation and the experiment carried out with the NiO-MgO catalyst at propane flow rate of 50 mL/min (standard conditions) and ethanol flow rate 0.3 mL/min (liq.) has revealed a discrepancy of less than 10%.

  16. Synthesis of 5-(hydroxymethyl)furfural in Ionic Liquids - Paving the Way to Renewable Chemicals

    DEFF Research Database (Denmark)

    Ståhlberg, Tim; Fu, Wenjing; Woodley, John

    2011-01-01

    The synthesis of 5-(hydroxymethyl)furfural (HMF) in ionic liquids is a field that has grown rapidly in recent years. Unique dissolving properties for crude biomass in combination with a high selectivity for HMF formation from hexose sugars make ionic liquids attractive reaction media for the prod......The synthesis of 5-(hydroxymethyl)furfural (HMF) in ionic liquids is a field that has grown rapidly in recent years. Unique dissolving properties for crude biomass in combination with a high selectivity for HMF formation from hexose sugars make ionic liquids attractive reaction media...... for the production of chemicals from renewable resources. A wide range of new catalytic systems that are unique for the transformation of glucose and fructose to HMF in ionic liquids has been found. However, literature examples of scale-up and process development are still scarce, and future research needs...... directions in process technology....

  17. Molecular genetic and molecular evolutionary studies on the bacteriochlorophyll synthesis genes of Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Burke-Agueero, D.H.

    1992-08-01

    Rhodobacter capsulatus, purple bacterium capable of either aerobic or photosynthetic growth, has proven to be very useful in genetic studies of photosynthesis. Forty-four genes clustered together within a 46 kilobase region are required to establish photosynthetic ability in R. capsulatus. Approximately twenty of these genes are involved in bacteriochlorophyll synthesis of which eight bch'' genes are the subject of this thesis. Six of these genes were found to code for the two ring reductases. The first converts protochlorophyllide (PChlide) into a chlorin, the immediate precursor to chlorophyll a, and then into a bacteriochlorin. Each reductase is shown to be made up of three subunits. PChlide reductase is coded by the genes bchN, bchB, and bchL. Proteins with amino acid sequences markedly similar to those of bchN and bchL have been shown in other organisms to be required for chlorophyll synthesis; hence, their designation as chlN and chlB. A third chloroplast-encoded gene of heretofore unknown function shares amino acid identities with bchB and is probably the third subunit of the plant PChlide reductase. The bchA locus, which encodes the chlorin reductase, is found to be made up of three separate, translationally coupled genes, referred to as bchX, bchY, and bchZ. Amino acid similarities between bchX, bchL, and the nitrogenase reductase protein nifH suggest that all three classes of proteins share certain three-dimensional structural features, including elements that are central to the enzymatic mechanism of nifH. PChlide reductase and chlorin reductase are clearly derived from a common ancestor. Several lines of analysis suggests the ancestor of both enzyme systems reduced PChlide twice to produce bacteriochlorophyll supporting the concept bacteriochlorophyll as the ancestral reaction center pigment.

  18. Molecular genetic and molecular evolutionary studies on the bacteriochlorophyll synthesis genes of Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Burke-Agueero, Donald H. [Univ. of California, Berkeley, CA (United States)

    1992-08-01

    Rhodobacter capsulatus, purple bacterium capable of either aerobic or photosynthetic growth, has proven to be very useful in genetic studies of photosynthesis. Forty-four genes clustered together within a 46 kilobase region are required to establish photosynthetic ability in R. capsulatus. Approximately twenty of these genes are involved in bacteriochlorophyll synthesis of which eight ``bch`` genes are the subject of this thesis. Six of these genes were found to code for the two ring reductases. The first converts protochlorophyllide (PChlide) into a chlorin, the immediate precursor to chlorophyll a, and then into a bacteriochlorin. Each reductase is shown to be made up of three subunits. PChlide reductase is coded by the genes bchN, bchB, and bchL. Proteins with amino acid sequences markedly similar to those of bchN and bchL have been shown in other organisms to be required for chlorophyll synthesis; hence, their designation as chlN and chlB. A third chloroplast-encoded gene of heretofore unknown function shares amino acid identities with bchB and is probably the third subunit of the plant PChlide reductase. The bchA locus, which encodes the chlorin reductase, is found to be made up of three separate, translationally coupled genes, referred to as bchX, bchY, and bchZ. Amino acid similarities between bchX, bchL, and the nitrogenase reductase protein nifH suggest that all three classes of proteins share certain three-dimensional structural features, including elements that are central to the enzymatic mechanism of nifH. PChlide reductase and chlorin reductase are clearly derived from a common ancestor. Several lines of analysis suggests the ancestor of both enzyme systems reduced PChlide twice to produce bacteriochlorophyll supporting the concept bacteriochlorophyll as the ancestral reaction center pigment.

  19. Miniature Chemical Sensor Combining Molecular Recognition with Evanescent Wave Cavity Ring-Down Spectroscopy

    International Nuclear Information System (INIS)

    Pipino, Andrew C. R.; Meuse, Curtis W.

    2002-01-01

    To address the chemical sensing needs of DOE, a new class of chemical sensors is being developed that enables qualitative and quantitative, remote, real-time, optical diagnostics of chemical species in hazardous gas, liquid, and semi-solid phases by employing evanescent wave cavity ringdown spectroscopy (EW-CRDS). The sensitivity of EW-CRDS was demonstrated previously under Project No.60231. The objective of this project is to enhance the range of application and selectivity of the technique by combining EW-CRDS with refractive-index-sensitive nanoparticle optics, molecular recognition (MR) chemistry, and by utilizing the polarization-dependence of EW-CRDS. Research Progress and Implications

  20. Correlation of chemical shifts predicted by molecular dynamics simulations for partially disordered proteins

    Energy Technology Data Exchange (ETDEWEB)

    Karp, Jerome M.; Erylimaz, Ertan; Cowburn, David, E-mail: cowburn@cowburnlab.org, E-mail: David.cowburn@einstein.yu.edu [Albert Einstein College of Medicine of Yeshiva University, Department of Biochemistry (United States)

    2015-01-15

    There has been a longstanding interest in being able to accurately predict NMR chemical shifts from structural data. Recent studies have focused on using molecular dynamics (MD) simulation data as input for improved prediction. Here we examine the accuracy of chemical shift prediction for intein systems, which have regions of intrinsic disorder. We find that using MD simulation data as input for chemical shift prediction does not consistently improve prediction accuracy over use of a static X-ray crystal structure. This appears to result from the complex conformational ensemble of the disordered protein segments. We show that using accelerated molecular dynamics (aMD) simulations improves chemical shift prediction, suggesting that methods which better sample the conformational ensemble like aMD are more appropriate tools for use in chemical shift prediction for proteins with disordered regions. Moreover, our study suggests that data accurately reflecting protein dynamics must be used as input for chemical shift prediction in order to correctly predict chemical shifts in systems with disorder.

  1. Synthesis of a novel iron oxide contrast agent as a platform for multimodal molecular imaging

    International Nuclear Information System (INIS)

    Borny, R.

    2014-01-01

    The purpose of this thesis was to create and characterize a functionalizable multimodal iron oxide nanoparticle, compare it with previously available designs and to create red blood cell carriers to increase the circulation time in vivo. The optimization of biological and physicochemical properties of the particles required the introduction of a new synthesis protocol: to reduce the reticuloendothelial uptake as well as to avoid extensive renal clearance, the overall hydrodynamic size was adjusted to 40 nm. The improvement of the chemical stability necessitated cross-linking of the dextran cage. Amine groups were created on the surface to enable particle functionalization. The synthesized nanoparticles (xION aerosole ) were precipitated from Fe 2+ and Fe 3+ (ratio 2:1) in the presence of monodispersed 10 kD dextran. The surface was cross-linked with epichlorohydrin and nucleophilized with ammonia. Ultrafiltration and dialysis was used for purification. The synthesized xION aerosole particles were compared with available products (Endorem®, Guerbet; Resovist®, Schering; Rienso®, Takeda). The hydrodynamic diameter and the core size were determined by transmission electron microscopy, electron tomography, laser light scattering and electron tomography. The amine groups were accessed by incubation with fluorescin isothiocyanate and the Fe 2+ /Fe 3+ ratio by Mössbauer spectroscopy. The relaxivity was measured at 1.5 T and 20°C. The physicochemical stability was assessed by Zeta potential, UV light irradiation till 9 Joule as well as laser light scattering during thermal cycling between 20 and 80°C. Three human cell lines (HAEC, HASMC, HELA) were used to evaluate the cellular uptake. The synthesized particles are stable at a broad pH range, biocompatible and have a potentially longer plasma half-life. Moreover, the relaxivity is comparable with commercial products and the particles are detectable at nanomolar concentrations. The theoretically postulated

  2. Molecular cloning and expression of Corynebacterium glutamicum genes for amino acid synthesis in Escherichia coli cells

    International Nuclear Information System (INIS)

    Beskrovnaya, O.Yu.; Fonshtein, M.Yu.; Kolibaba, L.G.; Yankovskii, N.K.; Debabov, V.G.

    1989-01-01

    Molecular cloning of Corynebacterium glutamicum genes for threonine and lysine synthesis has been done in Escherichia coli cells. The clonal library of EcoRI fragments of chromosomal DNA of C. glutamicum was constructed on the plasmid vector λpSL5. The genes for threonine and lysine synthesis were identified by complementation of E. coli mutations in thrB and lysA genes, respectively. Recombinant plasmids, isolated from independent ThrB + clone have a common 4.1-kb long EcoRI DNA fragment. Hybrid plasmids isolated from LysA + transductants of E. coli have common 2.2 and 3.3 kb long EcoRI fragments of C. glutamicum DNA. The hybrid plasmids consistently transduced the markers thrB + and lysA + . The Southern hybridization analysis showed that the cloned DNA fragments hybridized with the fragments of identical length in C. glutamicum chromosomes

  3. Optimisation of the synthesis of vancomycin-selective molecularly imprinted polymer nanoparticles using automatic photoreactor

    Science.gov (United States)

    Muzyka, Kateryna; Karim, Khalku; Guerreiro, Antonio; Poma, Alessandro; Piletsky, Sergey

    2014-03-01

    A novel optimized protocol for solid-state synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) with specificity for antibiotic vancomycin is described. The experimental objective was optimization of the synthesis parameters (factors) affecting the yield of obtained nanoparticles which have been synthesized using the first prototype of an automated solid-phase synthesizer. Applications of experimental design (or design of experiments) in optimization of nanoMIP yield were carried out using MODDE 9.0 software. The factors chosen in the model were the amount of functional monomers in the polymerization mixture, irradiation time, temperature during polymerization, and elution temperature. In general, it could be concluded that the irradiation time is the most important and the temperature was the least important factor which influences the yield of nanoparticles. Overall, the response surface methodology proved to be an effective tool in reducing time required for optimization of complex experimental conditions.

  4. Photocatalytic Properties of Nb/MCM-41 Molecular Sieves: Effect of the Synthesis Conditions

    Directory of Open Access Journals (Sweden)

    Caterine Daza Gomez

    2015-08-01

    Full Text Available The effect of synthesis conditions and niobium incorporation levels on the photocatalytic properties of Nb/MCM-41 molecular sieves was assessed. Niobium pentoxide supported on MCM-41 mesoporous silica was obtained using two methods: sol-gel and incipient impregnation, in each case also varying the percentage of niobium incorporation. The synthesized Nb-MCM-41 ceramic powders were characterized using the spectroscopic techniques of infrared spectroscopy (IR, Raman spectroscopy, X-ray diffraction (XRD, and transmission electron microscopy (TEM. The photodegradation capacity of the powders was studied using the organic molecule, methylene blue. The effect of both the method of synthesis and the percentage of niobium present in the sample on the photodegradation action of the solids was determined. The mesoporous Nb-MCM-41 that produced the greatest photodegradation response was obtained using the sol-gel method and 20% niobium incorporation.

  5. Tin-Assisted Synthesis of ɛ -Ga2O3 by Molecular Beam Epitaxy

    Science.gov (United States)

    Kracht, M.; Karg, A.; Schörmann, J.; Weinhold, M.; Zink, D.; Michel, F.; Rohnke, M.; Schowalter, M.; Gerken, B.; Rosenauer, A.; Klar, P. J.; Janek, J.; Eickhoff, M.

    2017-11-01

    The synthesis of ɛ -Ga2O3 and β -Ga2O3 by plasma-assisted molecular beam epitaxy on (001 )Al2O3 substrates is studied. The growth window of β -Ga2O3 in the Ga-rich regime, usually limited by the formation of volatile gallium suboxide, is expanded due to the presence of tin during the growth process, which stabilizes the formation of gallium oxides. X-ray diffraction, transmission electron microscopy, time-of-flight secondary-ion mass spectrometry, Raman spectroscopy, and atomic force microscopy are used to analyze the influence of tin on the layer formation. We demonstrate that it allows the synthesis of phase-pure ɛ -Ga2O3 . A growth model based on the oxidation of gallium suboxide by reduction of an intermediate sacrificial tin oxide is suggested.

  6. Heterogeneous chemical kinetics by modulated molecular beam mass spectrometry: limitations of technique

    International Nuclear Information System (INIS)

    Olander, D.R.

    1977-01-01

    The advantages and limitations of modulated molecular beam, mass spectrometry as applied to the study of heterogeneous chemical kinetics are reviewed. The process of deducing a model of the surface reaction from experimental data is illustrated by analysis of the hydrogen reduction of uranium dioxide

  7. Molecular dosimetry of chemical mutagens: measurement of molecular dose and DNA repair germ cells

    International Nuclear Information System (INIS)

    Sega, G.A.

    1975-01-01

    Molecular dosimetry in the germ cells of male mice is reviewed with regard to in vivo alkylation of sperm heads, in vivo alkylation of sperm DNA, and possible alkylation of sperm protamine. DNA repair in male germ cells is reviewed with regard to basic design of experiments, DNA repair in various stages of spermatogenesis, effect of protamine on DNA repair following treatment with EMS or x radiation, and induction of DNA repair by methyl methanesulfonate, propyl methanesulfonate, and isopropyl methanesulfonate

  8. Ordered molecular arrays as templates: A new approach to synthesis of mesoporous materials

    Science.gov (United States)

    Behrens, P.; Stucky, G.

    There has been a growing interest in the extension of the microporous molecular sieve synthesis and applications to mesoscopic dimensions. Typical areas for the application of mesoscopic zeolite-type structures are in separation (e.g., protein separation and selective adsorption of large organic molecules from waste waters) and catalysis (e.g., processing of tar sand and of the high distillates of crude oils to valuable low-boiling products). Another is in the supramolecular assembly of molecular array and polymers for electronic and optical applications. In a new concept in the synthesis of porous material the templating agent is no longer a single, solvated, organic molecule or metal ion, but rather a self-assembled molecular array. This template leads to mesoporous materials with adjustable pore sizes between 16 and greater than 100 Angstrom, covering well the mesophorous range of greatest interest. The periodic arrangement of pores is very regular, and the pore size distribution measured by absorption is nearly as sharp as that of conventional zeolites.

  9. Synthesis of neodymium hydroxide nanotubes and nanorods by soft chemical process.

    Science.gov (United States)

    Shi, Weidong; Yu, Jiangbo; Wang, Haishui; Yang, Jianhui; Zhang, Hongjie

    2006-08-01

    A facile soft chemical approach using cetyltrimethylammonium bromide (CTAB) as template is successfully designed for synthesis of neodymium hydroxide nanotubes. These nanotubes have an average outer diameter around 20 nm, inner diameter around 2 nm, and length ranging from 100 to 120 nm, high BET surface area of 495.71 m(2) g(-1). We also find that neodymium hydroxide nanorods would be obtained when CTAB absented in reaction system. The Nd(OH)3 nanorods might act as precursors that are converted into Nd2O3 nanorods through dehydration at 550 degrees C. The nanorods could exhibit upconversion emission characteristic under excitation of 591 nm at room temperature.

  10. [Synthesis and physico-chemical properties of lonazolac-Ca, a new antiphlogistic/antirheumatic agent].

    Science.gov (United States)

    Rainer, G; Krüger, U; Klemm, K

    1981-01-01

    Calcium-[3-(p-chlorophenyl)-1-phenylpyrazole-4]-acetate (Lonazolac-Ca, active principle of Irritren) is a new antiinflammatory/antirheumatic agent whose synthesis and physico-chemical properties are described. The physical parameters measured (pKa, partition coefficient P, saturation concentration Cs, surface activity, protein binding) are held against the corresponding values of indomethacin, diclofenac, and phenylbutazone. The size of the permeability coefficient PM of the passive transport through artificial phospholipid collodion membranes as well as the invasion curves calculated from PM indicate a good absorption of lonazolac in man.

  11. The Alexandria library, a quantum-chemical database of molecular properties for force field development.

    Science.gov (United States)

    Ghahremanpour, Mohammad M; van Maaren, Paul J; van der Spoel, David

    2018-04-10

    Data quality as well as library size are crucial issues for force field development. In order to predict molecular properties in a large chemical space, the foundation to build force fields on needs to encompass a large variety of chemical compounds. The tabulated molecular physicochemical properties also need to be accurate. Due to the limited transparency in data used for development of existing force fields it is hard to establish data quality and reusability is low. This paper presents the Alexandria library as an open and freely accessible database of optimized molecular geometries, frequencies, electrostatic moments up to the hexadecupole, electrostatic potential, polarizabilities, and thermochemistry, obtained from quantum chemistry calculations for 2704 compounds. Values are tabulated and where available compared to experimental data. This library can assist systematic development and training of empirical force fields for a broad range of molecules.

  12. The Alexandria library, a quantum-chemical database of molecular properties for force field development

    Science.gov (United States)

    Ghahremanpour, Mohammad M.; van Maaren, Paul J.; van der Spoel, David

    2018-04-01

    Data quality as well as library size are crucial issues for force field development. In order to predict molecular properties in a large chemical space, the foundation to build force fields on needs to encompass a large variety of chemical compounds. The tabulated molecular physicochemical properties also need to be accurate. Due to the limited transparency in data used for development of existing force fields it is hard to establish data quality and reusability is low. This paper presents the Alexandria library as an open and freely accessible database of optimized molecular geometries, frequencies, electrostatic moments up to the hexadecupole, electrostatic potential, polarizabilities, and thermochemistry, obtained from quantum chemistry calculations for 2704 compounds. Values are tabulated and where available compared to experimental data. This library can assist systematic development and training of empirical force fields for a broad range of molecules.

  13. Molecular descriptor data explain market prices of a large commercial chemical compound library

    Science.gov (United States)

    Polanski, Jaroslaw; Kucia, Urszula; Duszkiewicz, Roksana; Kurczyk, Agata; Magdziarz, Tomasz; Gasteiger, Johann

    2016-06-01

    The relationship between the structure and a property of a chemical compound is an essential concept in chemistry guiding, for example, drug design. Actually, however, we need economic considerations to fully understand the fate of drugs on the market. We are performing here for the first time the exploration of quantitative structure-economy relationships (QSER) for a large dataset of a commercial building block library of over 2.2 million chemicals. This investigation provided molecular statistics that shows that on average what we are paying for is the quantity of matter. On the other side, the influence of synthetic availability scores is also revealed. Finally, we are buying substances by looking at the molecular graphs or molecular formulas. Thus, those molecules that have a higher number of atoms look more attractive and are, on average, also more expensive. Our study shows how data binning could be used as an informative method when analyzing big data in chemistry.

  14. Chemical solution synthesis and ferromagnetic resonance of epitaxial thin films of yttrium iron garnet

    Science.gov (United States)

    Lucas, Irene; Jiménez-Cavero, Pilar; Vila-Fungueiriño, J. M.; Magén, Cesar; Sangiao, Soraya; de Teresa, José Maria; Morellón, Luis; Rivadulla, Francisco

    2017-12-01

    We report the fabrication of epitaxial Y3F e5O12 (YIG) thin films on G d3G a5O12 (111) using a chemical solution method. Cubic YIG is a ferrimagnetic material at room temperature, with excellent magneto-optical properties, high electrical resistivity, and a very narrow ferromagnetic resonance, which makes it particularly suitable for applications in filters and resonators at microwave frequencies. But these properties depend on the precise stoichiometry and distribution of F e3 + ions among the octahedral/tetrahedral sites of a complex structure, which hampered the production of high-quality YIG thin films by affordable chemical methods. Here we report the chemical solution synthesis of YIG thin films, with excellent chemical, crystalline, and magnetic homogeneity. The films show a very narrow ferromagnetic resonance (long spin relaxation time), comparable to that obtained from high-vacuum physical deposition methods. These results demonstrate that chemical methods can compete to develop nanometer-thick YIG films with the quality required for spintronic devices and other high-frequency applications.

  15. Endocrine-disrupting Chemicals: Review of Toxicological Mechanisms Using Molecular Pathway Analysis

    Science.gov (United States)

    Yang, Oneyeol; Kim, Hye Lim; Weon, Jong-Il; Seo, Young Rok

    2015-01-01

    Endocrine disruptors are known to cause harmful effects to human through various exposure routes. These chemicals mainly appear to interfere with the endocrine or hormone systems. As importantly, numerous studies have demonstrated that the accumulation of endocrine disruptors can induce fatal disorders including obesity and cancer. Using diverse biological tools, the potential molecular mechanisms related with these diseases by exposure of endocrine disruptors. Recently, pathway analysis, a bioinformatics tool, is being widely used to predict the potential mechanism or biological network of certain chemicals. In this review, we initially summarize the major molecular mechanisms involved in the induction of the above mentioned diseases by endocrine disruptors. Additionally, we provide the potential markers and signaling mechanisms discovered via pathway analysis under exposure to representative endocrine disruptors, bisphenol, diethylhexylphthalate, and nonylphenol. The review emphasizes the importance of pathway analysis using bioinformatics to finding the specific mechanisms of toxic chemicals, including endocrine disruptors. PMID:25853100

  16. Synthesis of mesoporous SAPO-34 molecular sieves and their applications in dehydration of butanols and ethanol.

    Science.gov (United States)

    Jun, Jong Won; Jeon, Jaewoo; Kim, Chul-Ung; Jeong, Kwang-Eun; Jeong, Soon-Yong; Jhung, Sung Hwa

    2013-04-01

    Microporous SAPO-34 molecular sieves were hydrothermally synthesized with microwave irradiation in the presence of tetraethylammonium hydroxide (TEAOH) as a template. SAPO-34 molecular sieves with mesoporosity were also prepared in the presence of carbon black as a hard template. By increasing the content of the carbon black template in the synthesis, the mesopore volume increased. Dehydration of alcohols (butanols and ethanol) was carried out with the synthesized SAPO-34 molecular sieves, and the lifetime of the catalysts for the dehydration reaction increased as the mesoporosity increased. Moreover, the performance of the microporous catalyst synthesized with microwave was better than that of the catalyst obtained with conventional electric heating. The relative performance of the catalytic dehydration may be explained by the mesoporosity and the crystal size. Therefore, it may be concluded that small-sized SAPO-34 molecular sieves with high mesoporosity can be produced efficiently with microwave irradiation in the presence of carbon black template, and the molecular sieves are effective in the stable dehydration of alcohols.

  17. Synthesis and Molecular Modeling of Thermally Stable DNA G-Quadruplexes with Anthraquinone Insertions

    DEFF Research Database (Denmark)

    Gouda, Alaa S.; Amine, Mahasen S.; Pedersen, Erik Bjerregaard

    2017-01-01

    Two new phosphoramidite building blocks for DNA synthesis were synthesized from 1,5- and 2,6-dihydroxyanthraquinones through alkylation with 3-bromo-1-propanol followed by DMT-protection. The novel synthesized 1,5- and 2,6-disubstituted anthraquinone monomers H15 and H26 are incorporated into a G...... anthraquinone-modified quadruplexes revealed no change of the antiparallel structure when compared with the wild type under potassium buffer conditions. The significantly increased thermostabilities were interpreted by molecular modeling of anthraquinone-modified G-quadruplexes....

  18. Racemic & quasi-racemic protein crystallography enabled by chemical protein synthesis.

    Science.gov (United States)

    Kent, Stephen Bh

    2018-04-04

    A racemic protein mixture can be used to form centrosymmetric crystals for structure determination by X-ray diffraction. Both the unnatural d-protein and the corresponding natural l-protein are made by total chemical synthesis based on native chemical ligation-chemoselective condensation of unprotected synthetic peptide segments. Racemic protein crystallography is important for structure determination of the many natural protein molecules that are refractory to crystallization. Racemic mixtures facilitate the crystallization of recalcitrant proteins, and give diffraction-quality crystals. Quasi-racemic crystallization, using a single d-protein molecule, can facilitate the determination of the structures of a series of l-protein analog molecules. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. In situ chemical synthesis of ruthenium oxide/reduced graphene oxide nanocomposites for electrochemical capacitor applications.

    Science.gov (United States)

    Kim, Ji-Young; Kim, Kwang-Heon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Park, Sang-Hoon; Kim, Kwang-Bum

    2013-08-07

    An in situ chemical synthesis approach has been developed to prepare ruthenium oxide/reduced graphene oxide (RGO) nanocomposites. It is found that as the C/O ratio increases, the number density of RuO2 nanoparticles decreases, because the chemical interaction between the Ru ions and the oxygen-containing functional groups provides anchoring sites where the nucleation of particles takes place. For electrochemical capacitor applications, the microwave-hydrothermal process was carried out to improve the conductivity of RGO in RuO2/RGO nanocomposites. The significant improvement in capacitance and high rate capability might result from the RuO2 nanoparticles used as spacers that make the interior layers of the reduced graphene oxide electrode available for electrolyte access.

  20. Room temperature synthesis and characterization of CdO nanowires by chemical bath deposition (CBD) method

    International Nuclear Information System (INIS)

    Dhawale, D.S.; More, A.M.; Latthe, S.S.; Rajpure, K.Y.; Lokhande, C.D.

    2008-01-01

    A chemical synthesis process for the fabrication of CdO nanowires is described. In the present work, transparent and conductive CdO films were synthesized on the glass substrate using chemical bath deposition (CBD) at room temperature. These films were annealed in air at 623 K and characterized for the structural, morphological, optical and electrical properties were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), optical and electrical resistivity. The XRD analysis showed that the as-deposited amorphous can be converted in to polycrystalline after annealing. Annealed CdO nanowires are 60-65 nm in diameter and length ranges typically from 2.5 to 3 μm. The optical properties revealed the presence of direct and indirect band gaps with energies 2.42 and 2.04 eV, respectively. Electrical resistivity measurement showed semiconducting behavior and thermoemf measurement showed n-type electrical conductivity

  1. Nonlinear Hamiltonian mechanics applied to molecular dynamics theory and computational methods for understanding molecular spectroscopy and chemical reactions

    CERN Document Server

    Farantos, Stavros C

    2014-01-01

    This brief presents numerical methods for describing and calculating invariant phase space structures, as well as solving the classical and quantum equations of motion for polyatomic molecules. Examples covered include simple model systems to realistic cases of molecules spectroscopically studied. Vibrationally excited and reacting molecules are nonlinear dynamical systems, and thus, nonlinear mechanics is the proper theory to elucidate molecular dynamics by investigating invariant structures in phase space. Intramolecular energy transfer, and the breaking and forming of a chemical bond have now found a rigorous explanation by studying phase space structures.

  2. Synthesis of Renewable Lubricant Alkanes from Biomass-Derived Platform Chemicals.

    Science.gov (United States)

    Gu, Mengyuan; Xia, Qineng; Liu, Xiaohui; Guo, Yong; Wang, Yanqin

    2017-10-23

    The catalytic synthesis of liquid alkanes from renewable biomass has received tremendous attention in recent years. However, bio-based platform chemicals have not to date been exploited for the synthesis of highly branched lubricant alkanes, which are currently produced by hydrocracking and hydroisomerization of long-chain n-paraffins. A selective catalytic synthetic route has been developed for the production of highly branched C 23 alkanes as lubricant base oil components from biomass-derived furfural and acetone through a sequential four-step process, including aldol condensation of furfural with acetone to produce a C 13 double adduct, selective hydrogenation of the adduct to a C 13 ketone, followed by a second condensation of the C 13 ketone with furfural to generate a C 23 aldol adduct, and finally hydrodeoxygenation to give highly branched C 23 alkanes in 50.6 % overall yield from furfural. This work opens a general strategy for the synthesis of high-quality lubricant alkanes from renewable biomass. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. QSAR analysis of salicylamide isosteres with the use of quantum chemical molecular descriptors.

    Science.gov (United States)

    Dolezal, R; Van Damme, S; Bultinck, P; Waisser, K

    2009-02-01

    Quantitative relationships between the molecular structure and the biological activity of 49 isosteric salicylamide derivatives as potential antituberculotics with a new mechanism of action against three Mycobacterial strains were investigated. The molecular structures were represented by quantum chemical B3LYP/6-31G( *) based molecular descriptors. A resulting set of 220 molecular descriptors, including especially electronic properties, was statistically analyzed using multiple linear regression, resulting in acceptable and robust QSAR models. The best QSAR model was found for Mycobacterium tuberculosis (r(2)=0.92; q(2)=0.89), and somewhat less good QSAR models were found for Mycobacterium avium (r(2)=0.84; q(2)=0.78) and Mycobacterium kansasii (r(2)=0.80; q(2)=0.56). All QSAR models were cross-validated using the leave-10-out procedure.

  4. Five Decades with Polyunsaturated Fatty Acids: Chemical Synthesis, Enzymatic Formation, Lipid Peroxidation and Its Biological Effects

    Directory of Open Access Journals (Sweden)

    Angel Catalá

    2013-01-01

    Full Text Available I have been involved in research on polyunsaturated fatty acids since 1964 and this review is intended to cover some of the most important aspects of this work. Polyunsaturated fatty acids have followed me during my whole scientific career and I have published a number of studies concerned with different aspects of them such as chemical synthesis, enzymatic formation, metabolism, transport, physical, chemical, and catalytic properties of a reconstructed desaturase system in liposomes, lipid peroxidation, and their effects. The first project I became involved in was the organic synthesis of [1-14C] eicosa-11,14-dienoic acid, with the aim of demonstrating the participation of that compound as a possible intermediary in the biosynthesis of arachidonic acid “in vivo.” From 1966 to 1982, I was involved in several projects that study the metabolism of polyunsaturated fatty acids. In the eighties, we studied fatty acid binding protein. From 1990 up to now, our laboratory has been interested in the lipid peroxidation of biological membranes from various tissues and different species as well as liposomes prepared with phospholipids rich in PUFAs. We tested the effect of many antioxidants such as alpha tocopherol, vitamin A, melatonin and its structural analogues, and conjugated linoleic acid, among others.

  5. Aligator: A computational tool for optimizing total chemical synthesis of large proteins.

    Science.gov (United States)

    Jacobsen, Michael T; Erickson, Patrick W; Kay, Michael S

    2017-09-15

    The scope of chemical protein synthesis (CPS) continues to expand, driven primarily by advances in chemical ligation tools (e.g., reversible solubilizing groups and novel ligation chemistries). However, the design of an optimal synthesis route can be an arduous and fickle task due to the large number of theoretically possible, and in many cases problematic, synthetic strategies. In this perspective, we highlight recent CPS tool advances and then introduce a new and easy-to-use program, Aligator (Automated Ligator), for analyzing and designing the most efficient strategies for constructing large targets using CPS. As a model set, we selected the E. coli ribosomal proteins and associated factors for computational analysis. Aligator systematically scores and ranks all feasible synthetic strategies for a particular CPS target. The Aligator script methodically evaluates potential peptide segments for a target using a scoring function that includes solubility, ligation site quality, segment lengths, and number of ligations to provide a ranked list of potential synthetic strategies. We demonstrate the utility of Aligator by analyzing three recent CPS projects from our lab: TNFα (157 aa), GroES (97 aa), and DapA (312 aa). As the limits of CPS are extended, we expect that computational tools will play an increasingly important role in the efficient execution of ambitious CPS projects such as production of a mirror-image ribosome. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Development of catalytic materials for the synthesis of valuable chemical products via multifunctional and multisite reactions

    International Nuclear Information System (INIS)

    Apesteguia, C.R; Padro, C.L; Diez, V.K; Di Cosimo, J.I; Trasarti, A.F; Marchi, A.J

    2004-01-01

    This work reports on the successful development of solid catalytic materials carried out by our working group to obtain fine high yield chemical products. Specifically, a report is made of i) the development of metal/acid bi-functional catalysts to obtain racemic menthol from citral in a one step liquid phase process. This menthol is one of the most important chemical flavouring compounds in industry; ii) The use of acid zeolites containing a balanced concentration of Bronsted and Lewis heavy acid sites, which allow the selective synthesis of o-hydroxy acetophenone from the gas phase acylation of phenol with acetic acid. The o-hydroxy acetophenone is an intermediate compound in the production of 4-hydroxy coumarin and warfarin that are used as anticoagulants drugs; iii) The use of mixed MgAl x O y oxides containing dual acid-basic sites (Mg 2- O 2- and Al 3+ -O 2- ) to synthesize isoforone from acetone in gas phase. The isoforone is an intermediate key in the synthesis of vitamin E (CW)

  7. Synthesis and Characterization of Carbon nanofibers on Co and Cu Catalysts by Chemical Vapor Deposition

    International Nuclear Information System (INIS)

    Park, Eunsil; Kim, Jongwon; Lee, Changseop

    2014-01-01

    This study reports on the synthesis of carbon nanofibers via chemical vapor deposition using Co and Cu as catalysts. In order to investigate the suitability of their catalytic activity for the growth of nanofibers, we prepared catalysts for the synthesis of carbon nanofibers with Cobalt nitrate and Copper nitrate, and found the optimum concentration of each respective catalyst. Then we made them react with Aluminum nitrate and Ammonium Molybdate to form precipitates. The precipitates were dried at a temperature of 110 .deg. C in order to be prepared into catalyst powder. The catalyst was sparsely and thinly spread on a quartz tube boat to grow carbon nanofibers via thermal chemical vapor deposition. The characteristics of the synthesized carbon nanofibers were analyzed through SEM, EDS, XRD, Raman, XPS, and TG/DTA, and the specific surface area was measured via BET. Consequently, the characteristics of the synthesized carbon nanofibers were greatly influenced by the concentration ratio of metal catalysts. In particular, uniform carbon nanofibers of 27 nm in diameter grew when the concentration ratio of Co and Cu was 6:4 at 700 .deg. C of calcination temperature; carbon nanofibers synthesized under such conditions showed the best crystallizability, compared to carbon nanofibers synthesized with metal catalysts under different concentration ratios, and revealed 1.26 high amorphicity as well as 292 m 2 g -1 high specific surface area

  8. Machine learning predictions of molecular properties: Accurate many-body potentials and nonlocality in chemical space

    International Nuclear Information System (INIS)

    Hansen, Katja; Biegler, Franziska; Ramakrishnan, Raghunathan; Pronobis, Wiktor; Lilienfeld, O. Anatole von; Müller, Klaus-Robert; Tkatchenko, Alexandre

    2015-01-01

    Simultaneously accurate and efficient prediction of molecular properties throughout chemical compound space is a critical ingredient toward rational compound design in chemical and pharmaceutical industries. Aiming toward this goal, we develop and apply a systematic hierarchy of efficient empirical methods to estimate atomization and total energies of molecules. These methods range from a simple sum over atoms, to addition of bond energies, to pairwise interatomic force fields, reaching to the more sophisticated machine learning approaches that are capable of describing collective interactions between many atoms or bonds. In the case of equilibrium molecular geometries, even simple pairwise force fields demonstrate prediction accuracy comparable to benchmark energies calculated using density functional theory with hybrid exchange-correlation functionals; however, accounting for the collective many-body interactions proves to be essential for approaching the 'holy grail' of chemical accuracy of 1 kcal/mol for both equilibrium and out-of-equilibrium geometries. This remarkable accuracy is achieved by a vectorized representation of molecules (so-called Bag of Bonds model) that exhibits strong nonlocality in chemical space. The same representation allows us to predict accurate electronic properties of molecules, such as their polarizability and molecular frontier orbital energies

  9. Influence of the synthesis parameters on the physico-chemical and catalytic properties of cerium oxide for application in the synthesis of diethyl carbonate

    International Nuclear Information System (INIS)

    Leino, Ewelina; Kumar, Narendra; Mäki-Arvela, Päivi; Aho, Atte; Kordás, Krisztián; Leino, Anne-Riikka; Shchukarev, Andrey; Murzin, Dmitry Yu.; Mikkola, Jyri-Pekka

    2013-01-01

    Synthesis of cerium (IV) oxide by means of room temperature precipitation method was carried out. The effect of preparation variables such as synthesis time, calcination temperature and pH of the solution on resulting CeO 2 properties was discussed. Moreover, the comparison of CeO 2 samples prepared in a static and rotation mode of synthesis is presented. The solid catalysts were characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscope, nitrogen physisorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy using pyridine as a probe molecule and temperature programmed desorption of CO 2 . Significant variations in physico-chemical properties of CeO 2 by varying the preparation conditions were observed. Furthermore, the catalytic performances of CeO 2 catalysts were compared in the synthesis of diethyl carbonate starting from ethanol and CO 2 using butylene oxide as a dehydrating agent. The dependence of CeO 2 properties on its catalytic activity is evaluated in detail. - Highlights: • Synthesis of cerium (IV) oxide by precipitation method. • Influence of synthesis time, calcination temperature, mode of stirring and solution pH on properties. • Characterization by XRD, SEM, TEM, nitrogen physisorption, XPS, FTIR. • Catalytic performance diethyl carbonate synthesis from ethanol and CO 2

  10. Detailed balance method for chemical potential determination in Monte Carlo and molecular dynamics simulations

    International Nuclear Information System (INIS)

    Fay, P.J.; Ray, J.R.; Wolf, R.J.

    1994-01-01

    We present a new, nondestructive, method for determining chemical potentials in Monte Carlo and molecular dynamics simulations. The method estimates a value for the chemical potential such that one has a balance between fictitious successful creation and destruction trials in which the Monte Carlo method is used to determine success or failure of the creation/destruction attempts; we thus call the method a detailed balance method. The method allows one to obtain estimates of the chemical potential for a given species in any closed ensemble simulation; the closed ensemble is paired with a ''natural'' open ensemble for the purpose of obtaining creation and destruction probabilities. We present results for the Lennard-Jones system and also for an embedded atom model of liquid palladium, and compare to previous results in the literature for these two systems. We are able to obtain an accurate estimate of the chemical potential for the Lennard-Jones system at higher densities than reported in the literature

  11. Existence of Inverted Profile in Chemically Responsive Molecular Pathways in the Zebrafish Liver

    Science.gov (United States)

    Zhang, Xun; Li, Hu; Ma, Jing; Zhang, Louxin; Li, Baowen; Gong, Zhiyuan

    2011-01-01

    How a living organism maintains its healthy equilibrium in response to endless exposure of potentially harmful chemicals is an important question in current biology. By transcriptomic analysis of zebrafish livers treated by various chemicals, we defined hubs as molecular pathways that are frequently perturbed by chemicals and have high degree of functional connectivity to other pathways. Our network analysis revealed that these hubs were organized into two groups showing inverted functionality with each other. Intriguingly, the inverted activity profiles in these two groups of hubs were observed to associate only with toxicopathological states but not with physiological changes. Furthermore, these inverted profiles were also present in rat, mouse, and human under certain toxicopathological conditions. Thus, toxicopathological-associated anti-correlated profiles in hubs not only indicate their potential use in diagnosis but also development of systems-based therapeutics to modulate gene expression by chemical approach in order to rewire the deregulated activities of hubs back to normal physiology. PMID:22140468

  12. Room temperature synthesis of porous SiO2 thin films by plasma enhanced chemical vapor deposition

    OpenAIRE

    Barranco Quero, Ángel; Cotrino Bautista, José; Yubero Valencia, Francisco; Espinós, J. P.; Rodríguez González-Elipe, Agustín

    2004-01-01

    Synthesis of porous SiO2 thin films in room temperature was carried out using plasma enhanced chemical vapor deposition (CVD) in an electron cyclotron resonance microwave reactor with a downstream configuration.The gas adsorption properties and the type of porosity of the SiO2 thin films were assessed by adsorption isotherms of toluene at room temperature.The method could also permit the tailoring synthesis of thin films when both composition and porosity can be simultaneously and independent...

  13. A review of engineering aspects of intensification of chemical synthesis using ultrasound.

    Science.gov (United States)

    Sancheti, Sonam V; Gogate, Parag R

    2017-05-01

    Cavitation generated using ultrasound can enhance the rates of several chemical reactions giving better selectivity based on the physical and chemical effects. The present review focuses on overview of the different reactions that can be intensified using ultrasound followed by the discussion on the chemical kinetics for ultrasound assisted reactions, engineering aspects related to reactor designs and effect of operating parameters on the degree of intensification obtained for chemical synthesis. The cavitational effects in terms of magnitudes of collapse temperatures and collapse pressure, number of free radicals generated and extent of turbulence are strongly dependent on the operating parameters such as ultrasonic power, frequency, duty cycle, temperature as well as physicochemical parameters of liquid medium which controls the inception of cavitation. Guidelines have been presented for the optimum selection based on the critical analysis of the existing literature so that maximum process intensification benefits can be obtained. Different reactor designs have also been analyzed with guidelines for efficient scale up of the sonochemical reactor, which would be dependent on the type of reaction, controlling mechanism of reaction, catalyst and activation energy requirements. Overall, it has been established that sonochemistry offers considerable potential for green and sustainable processing and efficient scale up procedures are required so as to harness the effects at actual commercial level. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Solid-Phase Synthesis of Molecularly Imprinted Polymer Nanoparticles with a Reusable Template - "Plastic Antibodies".

    Science.gov (United States)

    Poma, Alessandro; Guerreiro, Antonio; Whitcombe, Michael J; Piletska, Elena V; Turner, Anthony P F; Piletsky, Sergey A

    2013-06-13

    Molecularly Imprinted Polymers (MIPs) are generic alternatives to antibodies in sensors, diagnostics and separations. To displace biomolecules without radical changes in infrastructure in device manufacture, MIPs should share their characteristics (solubility, size, specificity and affinity, localized binding domain) whilst maintaining the advantages of MIPs (low-cost, short development time and high stability) hence the interest in MIP nanoparticles. Herein we report a reusable solid-phase template approach (fully compatible with automation) for the synthesis of MIP nanoparticles and their precise manufacture using a prototype automated UV photochemical reactor. Batches of nanoparticles (30-400 nm) with narrow size distributions imprinted with: melamine (d = 60 nm, K d = 6.3 × 10 -8 m), vancomycin (d = 250 nm, K d = 3.4 × 10 -9 m), a peptide (d = 350 nm, K d = 4.8 × 10 -8 m) and proteins have been produced. Our instrument uses a column packed with glass beads, bearing the template. Process parameters are under computer control, requiring minimal manual intervention. For the first time we demonstrate the reliable re-use of molecular templates in the synthesis of MIPs (≥ 30 batches of nanoMIPs without loss of performance). NanoMIPs are produced template-free and the solid-phase acts both as template and affinity separation medium.

  15. Synthesis and Guest Recognition of Switchable Pt-Salphen Based Molecular Tweezers

    Directory of Open Access Journals (Sweden)

    Lorien Benda

    2018-04-01

    Full Text Available Molecular tweezers are artificial receptors that have an open cavity generated by two recognition units pre-organized by a spacer. Switchable molecular tweezers, using a stimuli-responsive spacer, are particularly appealing as prototypes of the molecular machines that combine mechanical motion and allosteric recognition properties. In this present study, the synthesis of switchable molecular tweezers composed of a central terpyridine unit substituted in 4,4″ positions by two Pt(II-salphen complexes is reported. The terpyridine ligand can be reversibly converted upon Zn(II coordination from a free ‘U’-shaped closed form to a coordinated ‘W’ open form. This new substitution pattern enables a reverse control of the mechanical motion compared to the previously reported 6,6″ substituted terpyridine-based tweezers. Guest binding studies with aromatic guests showed an intercalation of coronene in the cavity created by the Pt-salphen moieties in the closed conformation. The formation of 1:1 host-guest complex was investigated by a combination of NMR studies and DFT calculations.

  16. Compensation effects in molecular interactions and the quantum chemical le Chatelier principle.

    Science.gov (United States)

    Mezey, Paul G

    2015-05-28

    Components of molecular interactions and various changes in the components of total energy changes during molecular processes typically exhibit some degrees of compensation. This may be as prominent as the over 90% compensation of the electronic energy and nuclear repulsion energy components of the total energy in some conformational changes. Some of these compensations are enhanced by solvent effects. For various arrangements of ions in a solvent, however, not only compensation but also a formal, mutual enhancement between the electronic energy and nuclear repulsion energy components of the total energy may also occur, when the tools of nuclear charge variation are applied to establish quantum chemically rigorous energy inequalities.

  17. Molecular beam studies of hot atom chemical reactions: Reactive scattering of energetic deuterium atoms

    International Nuclear Information System (INIS)

    Continetti, R.E.; Balko, B.A.; Lee, Y.T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H 2 /minus/> DH + H and the substitution reaction D + C 2 H 2 /minus/> C 2 HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible. 18 refs., 9 figs

  18. Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms

    Science.gov (United States)

    Continetti, R. E.; Balko, B. A.; Lee, Y. T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

  19. Chemical Reactivity and Spectroscopy Explored From QM/MM Molecular Dynamics Simulations Using the LIO Code

    Directory of Open Access Journals (Sweden)

    Juan P. Marcolongo

    2018-03-01

    Full Text Available In this work we present the current advances in the development and the applications of LIO, a lab-made code designed for density functional theory calculations in graphical processing units (GPU, that can be coupled with different classical molecular dynamics engines. This code has been thoroughly optimized to perform efficient molecular dynamics simulations at the QM/MM DFT level, allowing for an exhaustive sampling of the configurational space. Selected examples are presented for the description of chemical reactivity in terms of free energy profiles, and also for the computation of optical properties, such as vibrational and electronic spectra in solvent and protein environments.

  20. Chemical reactivity and spectroscopy explored from QM/MM molecular dynamics simulations using the LIO code

    Science.gov (United States)

    Marcolongo, Juan P.; Zeida, Ari; Semelak, Jonathan A.; Foglia, Nicolás O.; Morzan, Uriel N.; Estrin, Dario A.; González Lebrero, Mariano C.; Scherlis, Damián A.

    2018-03-01

    In this work we present the current advances in the development and the applications of LIO, a lab-made code designed for density functional theory calculations in graphical processing units (GPU), that can be coupled with different classical molecular dynamics engines. This code has been thoroughly optimized to perform efficient molecular dynamics simulations at the QM/MM DFT level, allowing for an exhaustive sampling of the configurational space. Selected examples are presented for the description of chemical reactivity in terms of free energy profiles, and also for the computation of optical properties, such as vibrational and electronic spectra in solvent and protein environments.

  1. Estrogen Regulates Protein Synthesis and Actin Polymerization in Hippocampal Neurons through Different Molecular Mechanisms

    Science.gov (United States)

    Briz, Victor; Baudry, Michel

    2014-01-01

    Estrogen rapidly modulates hippocampal synaptic plasticity by activating selective membrane-associated receptors. Reorganization of the actin cytoskeleton and stimulation of mammalian target of rapamycin (mTOR)-mediated protein synthesis are two major events required for the consolidation of hippocampal long-term potentiation and memory. Estradiol regulates synaptic plasticity by interacting with both processes, but the underlying molecular mechanisms are not yet fully understood. Here, we used acute rat hippocampal slices to analyze the mechanisms underlying rapid changes in mTOR activity and actin polymerization elicited by estradiol. Estradiol-induced mTOR phosphorylation was preceded by rapid and transient activation of both extracellular signal-regulated kinase (ERK) and protein kinase B (Akt) and by phosphatase and tensin homolog (PTEN) degradation. These effects were prevented by calpain and ERK inhibitors. Estradiol-induced mTOR stimulation did not require activation of classical estrogen receptors (ER), as specific ERα and ERβ agonists (PPT and DPN, respectively) failed to mimic this effect, and ER antagonists could not block it. Estradiol rapidly activated both RhoA and p21-activated kinase (PAK). Furthermore, a specific inhibitor of RhoA kinase (ROCK), H1152, and a potent and specific PAK inhibitor, PF-3758309, blocked estradiol-induced cofilin phosphorylation and actin polymerization. ER antagonists also blocked these effects of estrogen. Consistently, both PPT and DPN stimulated PAK and cofilin phosphorylation as well as actin polymerization. Finally, the effects of estradiol on actin polymerization were insensitive to protein synthesis inhibitors, but its stimulation of mTOR activity was impaired by latrunculin A, a drug that disrupts actin filaments. Taken together, our results indicate that estradiol regulates local protein synthesis and cytoskeletal reorganization via different molecular mechanisms and signaling pathways. PMID:24611062

  2. Linguistic measures of chemical diversity and the "keywords" of molecular collections.

    Science.gov (United States)

    Woźniak, Michał; Wołos, Agnieszka; Modrzyk, Urszula; Górski, Rafał L; Winkowski, Jan; Bajczyk, Michał; Szymkuć, Sara; Grzybowski, Bartosz A; Eder, Maciej

    2018-05-15

    Computerized linguistic analyses have proven of immense value in comparing and searching through large text collections ("corpora"), including those deposited on the Internet - indeed, it would nowadays be hard to imagine browsing the Web without, for instance, search algorithms extracting most appropriate keywords from documents. This paper describes how such corpus-linguistic concepts can be extended to chemistry based on characteristic "chemical words" that span more than traditional functional groups and, instead, look at common structural fragments molecules share. Using these words, it is possible to quantify the diversity of chemical collections/databases in new ways and to define molecular "keywords" by which such collections are best characterized and annotated.

  3. Gas-Phase Molecular Dynamics: Theoretical Studies In Spectroscopy and Chemical Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yu H. G.; Muckerman, J.T.

    2012-05-29

    The main goal of this program is the development and application of computational methods for studying chemical reaction dynamics and molecular spectroscopy in the gas phase. We are interested in developing rigorous quantum dynamics algorithms for small polyatomic systems and in implementing approximate approaches for complex ones. Particular focus is on the dynamics and kinetics of chemical reactions and on the rovibrational spectra of species involved in combustion processes. This research also explores the potential energy surfaces of these systems of interest using state-of-the-art quantum chemistry methods, and extends them to understand some important properties of materials in condensed phases and interstellar medium as well as in combustion environments.

  4. Gas-Phase Molecular Dynamics: Theoretical Studies in Spectroscopy and Chemical Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H.G.; Muckerman, J.T.

    2010-06-01

    The goal of this program is the development and application of computational methods for studying chemical reaction dynamics and molecular spectroscopy in the gas phase. We are interested in developing rigorous quantum dynamics algorithms for small polyatomic systems and in implementing approximate approaches for complex ones. Particular focus is on the dynamics and kinetics of chemical reactions and on the rovibrational spectra of species involved in combustion processes. This research also explores the potential energy surfaces of these systems of interest using state-of-the-art quantum chemistry methods.

  5. Molecular basis sets - a general similarity-based approach for representing chemical spaces.

    Science.gov (United States)

    Raghavendra, Akshay S; Maggiora, Gerald M

    2007-01-01

    A new method, based on generalized Fourier analysis, is described that utilizes the concept of "molecular basis sets" to represent chemical space within an abstract vector space. The basis vectors in this space are abstract molecular vectors. Inner products among the basis vectors are determined using an ansatz that associates molecular similarities between pairs of molecules with their corresponding inner products. Moreover, the fact that similarities between pairs of molecules are, in essentially all cases, nonzero implies that the abstract molecular basis vectors are nonorthogonal, but since the similarity of a molecule with itself is unity, the molecular vectors are normalized to unity. A symmetric orthogonalization procedure, which optimally preserves the character of the original set of molecular basis vectors, is used to construct appropriate orthonormal basis sets. Molecules can then be represented, in general, by sets of orthonormal "molecule-like" basis vectors within a proper Euclidean vector space. However, the dimension of the space can become quite large. Thus, the work presented here assesses the effect of basis set size on a number of properties including the average squared error and average norm of molecular vectors represented in the space-the results clearly show the expected reduction in average squared error and increase in average norm as the basis set size is increased. Several distance-based statistics are also considered. These include the distribution of distances and their differences with respect to basis sets of differing size and several comparative distance measures such as Spearman rank correlation and Kruscal stress. All of the measures show that, even though the dimension can be high, the chemical spaces they represent, nonetheless, behave in a well-controlled and reasonable manner. Other abstract vector spaces analogous to that described here can also be constructed providing that the appropriate inner products can be directly

  6. Molecular structures enumeration and virtual screening in the chemical space with RetroPath2.0.

    Science.gov (United States)

    Koch, Mathilde; Duigou, Thomas; Carbonell, Pablo; Faulon, Jean-Loup

    2017-12-19

    Network generation tools coupled with chemical reaction rules have been mainly developed for synthesis planning and more recently for metabolic engineering. Using the same core algorithm, these tools apply a set of rules to a source set of compounds, stopping when a sink set of compounds has been produced. When using the appropriate sink, source and rules, this core algorithm can be used for a variety of applications beyond those it has been developed for. Here, we showcase the use of the open source workflow RetroPath2.0. First, we mathematically prove that we can generate all structural isomers of a molecule using a reduced set of reaction rules. We then use this enumeration strategy to screen the chemical space around a set of monomers and predict their glass transition temperatures, as well as around aminoglycosides to search structures maximizing antibacterial activity. We also perform a screening around aminoglycosides with enzymatic reaction rules to ensure biosynthetic accessibility. We finally use our workflow on an E. coli model to complete E. coli metabolome, with novel molecules generated using promiscuous enzymatic reaction rules. These novel molecules are searched on the MS spectra of an E. coli cell lysate interfacing our workflow with OpenMS through the KNIME Analytics Platform. We provide an easy to use and modify, modular, and open-source workflow. We demonstrate its versatility through a variety of use cases including molecular structure enumeration, virtual screening in the chemical space, and metabolome completion. Because it is open source and freely available on MyExperiment.org, workflow community contributions should likely expand further the features of the tool, even beyond the use cases presented in the paper.

  7. Chemical synthesis of porous web-structured CdS thin films for photosensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Gosavi, S.R., E-mail: srgosavi.taloda@gmail.com [C. H. C. Arts, S. G. P. Commerce, and B. B. J. P. Science College, Taloda, Dist., Nandurbar 425413, M. S. (India); Nikam, C.P. [B.S.S.P.M.S. Arts, Commerce and Science College, Songir, Dist., Dhule 424309, M. S. (India); Shelke, A.R.; Patil, A.M. [Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India); Ryu, S.-W. [Department of Physics, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Bhat, J.S. [Department of Physics, Karnatak University, Dharwad 580003 (India); Deshpande, N.G., E-mail: nicedeshpande@yahoo.co.in [Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India)

    2015-06-15

    The photo-activity of chemically deposited cadmium sulphide (CdS) thin film has been studied. The simple chemical route nucleates the CdS films with size up to the mean free path of the electron. Growth Kinematics of crystalline hexagonal CdS phase in the thin film form was monitored using X-ray diffraction. The time limitation set for the formation of the amorphous/nano-crystalline material is 40 and 60 min. Thereafter enhancement of the crystalline orientation along the desired plane was identified. Web-like porous structured surface morphology of CdS thin film over the entire area is observed. With decrease in synthesis time, increase of band gap energy i.e., a blue spectral shift was seen. The activation energy of CdS thin film at low and high temperature region was examined. It is considered that this activation energy corresponds to the donor levels associated with shallow traps or surface states of CdS thin film. The photo-electrochemical performance of CdS thin films in polysulphide electrolyte showed diode-like characteristics. Exposure of light on the CdS electrode increases the photocurrent. This suggests the possibility of production of free carriers via excited ions and also the light harvesting mechanism due to porous web-structured morphology. These studies hint that the obtained CdS films can work as a photosensor. - Highlights: • Photoactivity of chemically synthesized cadmium sulphide (CdS) thin films was studied. • Web-like porous structured surface morphology of CdS thin film over the entire area was observed. • Blue spectral shift with lowering of the synthesis time suggests films can act as a window layer over the absorber layer. • Porous web-structured CdS thin films can be useful in light harvesting.

  8. Chemical synthesis of porous web-structured CdS thin films for photosensor applications

    International Nuclear Information System (INIS)

    Gosavi, S.R.; Nikam, C.P.; Shelke, A.R.; Patil, A.M.; Ryu, S.-W.; Bhat, J.S.; Deshpande, N.G.

    2015-01-01

    The photo-activity of chemically deposited cadmium sulphide (CdS) thin film has been studied. The simple chemical route nucleates the CdS films with size up to the mean free path of the electron. Growth Kinematics of crystalline hexagonal CdS phase in the thin film form was monitored using X-ray diffraction. The time limitation set for the formation of the amorphous/nano-crystalline material is 40 and 60 min. Thereafter enhancement of the crystalline orientation along the desired plane was identified. Web-like porous structured surface morphology of CdS thin film over the entire area is observed. With decrease in synthesis time, increase of band gap energy i.e., a blue spectral shift was seen. The activation energy of CdS thin film at low and high temperature region was examined. It is considered that this activation energy corresponds to the donor levels associated with shallow traps or surface states of CdS thin film. The photo-electrochemical performance of CdS thin films in polysulphide electrolyte showed diode-like characteristics. Exposure of light on the CdS electrode increases the photocurrent. This suggests the possibility of production of free carriers via excited ions and also the light harvesting mechanism due to porous web-structured morphology. These studies hint that the obtained CdS films can work as a photosensor. - Highlights: • Photoactivity of chemically synthesized cadmium sulphide (CdS) thin films was studied. • Web-like porous structured surface morphology of CdS thin film over the entire area was observed. • Blue spectral shift with lowering of the synthesis time suggests films can act as a window layer over the absorber layer. • Porous web-structured CdS thin films can be useful in light harvesting

  9. Synthesis of cerium oxide catalysts supported on MCM-41 molecular sieve

    International Nuclear Information System (INIS)

    Souza, E.L.S.; Barros, T.R.B.; Sousa, B.V. de

    2016-01-01

    Porous materials have been widely studied as catalysts and catalyst support. The MCM-41 structure is the one that has been most studied because of its application possibilities in chemical processes. This work aimed to obtain and characterize cerium oxide catalysts supported on MCM-41 molecular sieve. The molecular sieve was synthesized by the conventional method with the following molar composition: 1 SiO2: 0.30 CTABr: NH3 11: 144 H2O. Then, 25% w/w cerium was incorporated into the MCM-41 using the wet impregnation process and the material obtained was activated by calcination. From the XRD patterns was confirmed the structure of the molecular sieve, and were identified the cerium oxide phases in its structure. The textural catalysts characteristics were investigated by isotherms of N2 adsorption/desorption (BET method). (author)

  10. Real-Time Molecular Monitoring of Chemical Environment in ObligateAnaerobes during Oxygen Adaptive Response

    Energy Technology Data Exchange (ETDEWEB)

    Holman, Hoi-Ying N.; Wozei, Eleanor; Lin, Zhang; Comolli, Luis R.; Ball, David. A.; Borglin, Sharon; Fields, Matthew W.; Hazen, Terry C.; Downing, Kenneth H.

    2009-02-25

    Determining the transient chemical properties of the intracellular environment canelucidate the paths through which a biological system adapts to changes in its environment, for example, the mechanisms which enable some obligate anaerobic bacteria to survive a sudden exposure to oxygen. Here we used high-resolution Fourier Transform Infrared (FTIR) spectromicroscopy to continuously follow cellular chemistry within living obligate anaerobes by monitoring hydrogen bonding in their cellular water. We observed a sequence of wellorchestrated molecular events that correspond to changes in cellular processes in those cells that survive, but only accumulation of radicals in those that do not. We thereby can interpret the adaptive response in terms of transient intracellular chemistry and link it to oxygen stress and survival. This ability to monitor chemical changes at the molecular level can yield important insights into a wide range of adaptive responses.

  11. Molecular characterization of kerogens by mild selective chemical degradation - ruthenium tetroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Boucher, R.J.; Standen, G.; Eglinton, G. (University of Bristol, Bristol (UK). Organic Geochemistry Unit)

    1991-06-01

    Molecular characterization of two kerogen isolates (Messel and Kimmeridge Clay), two kerogen-rich shales (green River and Maoming) and a coal, (Loy Yang) was undertaken using selective chemical degradation with ruthenium tetroxide (RuO{sub 4}). The RuO{sub 4} oxidation gave extracts which were soluble in dichloromethane and contained series of straight chain monocarboxylic acids, {alpha},{omega}-dicarboxylic acids, branched mono- and dicarboxylic acids, isoprenoid and cyclic acids. Straight chain carboxylic acids were predominant (65-87% of quantified chromatogram components for the range of sedimentary organic matter studied), reflecting the major content of polymethylene chains in these kerogens. This mild, oxidative technique serves to differentiate kerogens at a molecular level, thereby supplementing existing conventional chemical, pyrolytic, n.m.r. and other techniques. 39 refs., 3 figs., 5 tabs.

  12. N-substituted-piperidines as Novel Anti-alzheimer Agents: Synthesis, antioxidant activity, and molecular docking study

    Directory of Open Access Journals (Sweden)

    Khairia M. Youssef

    2018-06-01

    Full Text Available Design, synthesis and evaluation of new acetylcholinesterase inhibitors by combining carbamoylpiperidine analogs containing nipecotic acid scaffold were described. Then, a series of hybrids have been developed by introducing Free radical scavengers. Molecular modeling was performed and structure activity relationships are discussed. Among the series, most potent compounds showed effective AchE inhibitions, high selectivity over butyrylcholinesterase and high radical scavenging activities. On the basis of this work, the ability of analogs containing nipecotic acid scaffold to serve in the design of N-benzyl-piperidine linked multipotent molecules for the treatment of Alzheimer Disease. Keywords: Synthesis, N-substituted-piperidines, Antioxidant activity, ATP chemiluminescence, Molecular modeling study

  13. The impact of chemical structure and molecular packing on the electronic polarisation of fullerene arrays.

    Science.gov (United States)

    Few, Sheridan; Chia, Cleaven; Teo, Daniel; Kirkpatrick, James; Nelson, Jenny

    2017-07-19

    Electronic polarisation contributes to the electronic landscape as seen by separating charges in organic materials. The nature of electronic polarisation depends on the polarisability, density, and arrangement of polarisable molecules. In this paper, we introduce a microscopic, coarse-grained model in which we treat each molecule as a polarisable site, and use an array of such polarisable dipoles to calculate the electric field and associated energy of any arrangement of charges in the medium. The model incorporates chemical structure via the molecular polarisability and molecular packing patterns via the structure of the array. We use this model to calculate energies of charge pairs undergoing separation in finite fullerene lattices of different chemical and crystal structures. The effective dielectric constants that we estimate from this approach are in good quantitative agreement with those measured experimentally in C 60 and phenyl-C 61 -butyric acid methyl ester (PCBM) films, but we find significant differences in dielectric constant depending on packing and on direction of separation, which we rationalise in terms of density of polarisable fullerene cages in regions of high field. In general, we find lattices containing molecules of more isotropic polarisability tensors exhibit higher dielectric constants. By exploring several model systems we conclude that differences in molecular polarisability (and therefore, chemical structure) appear to be less important than differences in molecular packing and separation direction in determining the energetic landscape for charge separation. We note that the results are relevant for finite lattices, but not necessarily for infinite systems. We propose that the model could be used to design molecular systems for effective electronic screening.

  14. Design, synthesis, conformational and molecular docking study of some novel acyl hydrazone based molecular hybrids as antimalarial and antimicrobial agents.

    Science.gov (United States)

    Kumar, Parvin; Kadyan, Kulbir; Duhan, Meenakshi; Sindhu, Jayant; Singh, Vineeta; Saharan, Baljeet Singh

    2017-11-14

    Acyl hydrazones are an important class of heterocyclic compounds promising pharmacological characteristics. Malaria is a life-threatening mosquito-borne blood disease caused by a plasmodium parasite. In some places, malaria can be treated and controlled with early diagnosis. However, some countries lack the resources to do this effectively. The present work involves the design and synthesis of some novel acyl hydrazone based molecular hybrids of 1,4-dihydropyridine and pyrazole (5a-g). These molecular hybrids were synthesised by condensation of 1,4-dihydropyridin-4-yl-phenoxyacetohydrazides with differently substituted pyrazole carbaldehyde. The final compound (5) showed two conformations (the major, E, s-cis and the minor, E, s-trans) as revealed by NMR spectral data and further supported by the energy calculations (MOPAC2016 using PM7 method). All the synthesised compounds were screened for their in vitro antimalarial activities against chloroquine-sensitive malaria parasite Plasmodium falciparum (3D7) and antimicrobial activity against Gram positive bacteria i.e. Bacillus cereus, Gram negative bacteria i.e. Escherichia coli and antifungal activity against one yeast i.e. Aspergillus niger. All these compounds were found more potent than chloroquine and clotrimazole, the standard drugs. In vitro antiplasmodial IC 50 value of the most potent compound 5d was found to be 4.40 nM which is even less than all the three reference drugs chloroquine (18.7 nM), pyrimethamine (11 nM) and artimisinin (6 nM). In silico binding study of compound 5d with plasmodial cysteine protease falcipain-2 indicated the inhibition of falcipain-2 as the probable reason for the antimalarial potency of compound 5d. All the compounds had shown good to excellent antimicrobial and antifungal activities.

  15. CurlySMILES: a chemical language to customize and annotate encodings of molecular and nanodevice structures

    Directory of Open Access Journals (Sweden)

    Drefahl Axel

    2011-01-01

    Full Text Available Abstract CurlySMILES is a chemical line notation which extends SMILES with annotations for storage, retrieval and modeling of interlinked, coordinated, assembled and adsorbed molecules in supramolecular structures and nanodevices. Annotations are enclosed in curly braces and anchored to an atomic node or at the end of the molecular graph depending on the annotation type. CurlySMILES includes predefined annotations for stereogenicity, electron delocalization charges, extra-molecular interactions and connectivity, surface attachment, solutions, and crystal structures and allows extensions for domain-specific annotations. CurlySMILES provides a shorthand format to encode molecules with repetitive substructural parts or motifs such as monomer units in macromolecules and amino acids in peptide chains. CurlySMILES further accommodates special formats for non-molecular materials that are commonly denoted by composition of atoms or substructures rather than complete atom connectivity.

  16. The Chemical Basis for the Origin of the Genetic Code and the Process of Protein Synthesis

    Science.gov (United States)

    Lacey, James C., Jr.

    1990-01-01

    A model for the origin of protein synthesis. The essential features of the model are that 5'-AMP and perhaps other monoribonucleotides can serve as catalysts for the selective synthesis of L-based peptides. A unique set of characteristics of 5'-AMP is responsible for the selective catalysts and these characteristics are described in detail. The model involves the formation of diesters as intermediates and selectivity for use of the L-isomer occurs principally at the step of forming the diester. However, in the formation of acetyl phenylalanine-AMP monoester there is a selectivity for esterification by the D-isomer. Data showing this selectivity is presented. This selectivity for D-isomer disappears after the first step. The identity was confirmed of all four of possible diesters of acetyl-D- and -L phenylaline with 5'-AMP by nuclear magnetic resonance (NMR). The data using flourescence and NMR show the Trp ring can associate with the adenine ring more strongly when the D-isomer is in the 2' position than it can when in the 3' position. These same data also suggest a molecular mechanisim for the faster esterificaton of 5'-AMP by acetyl-D-phenylaline. Some new data is also presented on the possible structure of the 2' isomer of acetyl-D-tryptophan-AMP monoester. The HPLC elution times of all four possible acetyl diphenylalanine esters of 5'-AMP were studied, these peptidyl esters will be products in the studies of peptide formation on the ribose of 5'-AMP. Other studies were on the rate of synthesis and the identity of the product when producing 3'Ac-Phe-2'tBOC-Phe-AMP diester. HPLC purification and identification of this product were accomplished.

  17. Synthesis and properties of functionalized 4 nm scale molecular wires with thiolated termini for self-assembly onto metal surfaces.

    Science.gov (United States)

    Wang, Changsheng; Bryce, Martin R; Gigon, Joanna; Ashwell, Geoffrey J; Grace, Iain; Lambert, Colin J

    2008-07-04

    We report the synthesis of new oligo(aryleneethynylene) molecular wires of ca. 4 nm length scale by palladium-catalyzed Sonogashira cross-coupling methodology. Key structural features are the presence of electron donor 9-(1,3-dithiol-2-ylidene)fluorene (compounds 13 and 14) and electron acceptor 9-[di(4-pyridyl)methylene]fluorene units (compound 16) at the core of the molecules. Terminal thiolate substituents are protected as cyanoethylsulfanyl (13 and 16) or thioacetate derivatives (14). The molecules display well-defined redox processes in solution electrochemical studies. The optical properties in solution are similar to those of the fluorenone analog 6: the strongest absorptions for 6, 13 and 16 are in the region lambda(max) = 387-393 nm, with 13 showing an additional shoulder at 415 nm which is not present for 6 and 16; this shoulder is assigned to a HOMO-LUMO transition from the dithiole to the fluorene unit. Molecules 6, 13, 14 and 16 form self-assembled monolayers on gold substrates which exhibit essentially symmetrical current-voltage (I-V) characteristics when contacted by a gold scanning tunelling microscope (STM) tip. The effects of the chemical modifications at the central unit of 6, 14 and 16 on the HOMO-LUMO levels and electron transport through the molecules in vacuum have been computed by an ab initio approach.

  18. SYNTHESIS AND PHYSICAL-CHEMICAL PROPERTIES OF WATER-SOLUBLE 3-BENZYLXANTHINE DERIVATIVES

    Directory of Open Access Journals (Sweden)

    K. V. Аleksandrova

    2015-04-01

    Full Text Available Introduction Nowadays, research of novel biological active compounds with low toxicity, are carried out among different classes of organic compounds of natural and synthetic genesis. One of the main ways of these studies is search of water-soluble compounds – convenient objects for pharmacological researches. In recent years researchers paid attention to xanthine derivatives, because of their high variativity of possible chemical modification and ability to form different salts with wide spectrum of biological action. Thus, among water-soluble xanthine derivatives were found compounds with pronounced antioxidant, diuretic and analeptic properties. Primary methods of obtaining water-soluble xanthine derivatives are direct interaction of bases with xanthine molecule or insertion basic or acidic residues in positions 7 or 8 of xanthine bicycle. According from the above, search of biologically active compounds among water-soluble substituted xanthines is prospective and actual. The aim of the study was development of synthetic ways of obtaining novel water-soluble derivatives of 3-benzyl-8-methylxanthine and studying their physical and chemical properties. Material and methods Melting points of obtained compounds were determined by capillary method on PTP (M device. ІR-spectra of synthesized compounds were recorded on the Bruker Alpha device (company «Bruker» – Germany on 4000-400 sm-1 with using console ATR (direct insertion of compound. 1Н NMR-spectra were recorded on the Varian Mercury VX-200 device (company «Varian» – USA solvent – (DMSO-d6, internal standart – ТМС. Elemental analysis was made on Elementar Vario L cube device. Chromatoraphic studies were made on the plates Sorbfil-AFV-UV (company «Sobrpolimer» –Russia. Systhems for chromatography: «acetone-propanol-2» in ratio 2:3, «propanol-2-benzene» in ratio 10:1 and exersized in UV-light in wave 200-300 nm. Results and discussion We developed methodic of synthesis

  19. Insulin-like Growth Factor 1 Analogs Clicked in the C Domain: Chemical Synthesis and Biological Activities

    Czech Academy of Sciences Publication Activity Database

    Macháčková, Kateřina; Collinsová, Michaela; Chrudinová, Martina; Selicharová, Irena; Pícha, Jan; Buděšínský, Miloš; Vaněk, Václav; Žáková, Lenka; Brzozowski, A. M.; Jiráček, Jiří

    2017-01-01

    Roč. 60, č. 24 (2017), s. 10105-10117 ISSN 0022-2623 Institutional support: RVO:61388963 Keywords : IGF-1 * receptor * synthesis * triazole Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 6.259, year: 2016 http://pubs.acs.org/doi/full/10.1021/acs.jmedchem.7b01331

  20. Automated chemical kinetic modeling via hybrid reactive molecular dynamics and quantum chemistry simulations.

    Science.gov (United States)

    Döntgen, Malte; Schmalz, Felix; Kopp, Wassja A; Kröger, Leif C; Leonhard, Kai

    2018-06-13

    An automated scheme for obtaining chemical kinetic models from scratch using reactive molecular dynamics and quantum chemistry simulations is presented. This methodology combines the phase space sampling of reactive molecular dynamics with the thermochemistry and kinetics prediction capabilities of quantum mechanics. This scheme provides the NASA polynomial and modified Arrhenius equation parameters for all species and reactions that are observed during the simulation and supplies them in the ChemKin format. The ab initio level of theory for predictions is easily exchangeable and the presently used G3MP2 level of theory is found to reliably reproduce hydrogen and methane oxidation thermochemistry and kinetics data. Chemical kinetic models obtained with this approach are ready-to-use for, e.g., ignition delay time simulations, as shown for hydrogen combustion. The presented extension of the ChemTraYzer approach can be used as a basis for methodologically advancing chemical kinetic modeling schemes and as a black-box approach to generate chemical kinetic models.

  1. Molecular finite-size effects in stochastic models of equilibrium chemical systems.

    Science.gov (United States)

    Cianci, Claudia; Smith, Stephen; Grima, Ramon

    2016-02-28

    The reaction-diffusion master equation (RDME) is a standard modelling approach for understanding stochastic and spatial chemical kinetics. An inherent assumption is that molecules are point-like. Here, we introduce the excluded volume reaction-diffusion master equation (vRDME) which takes into account volume exclusion effects on stochastic kinetics due to a finite molecular radius. We obtain an exact closed form solution of the RDME and of the vRDME for a general chemical system in equilibrium conditions. The difference between the two solutions increases with the ratio of molecular diameter to the compartment length scale. We show that an increase in the fraction of excluded space can (i) lead to deviations from the classical inverse square root law for the noise-strength, (ii) flip the skewness of the probability distribution from right to left-skewed, (iii) shift the equilibrium of bimolecular reactions so that more product molecules are formed, and (iv) strongly modulate the Fano factors and coefficients of variation. These volume exclusion effects are found to be particularly pronounced for chemical species not involved in chemical conservation laws. Finally, we show that statistics obtained using the vRDME are in good agreement with those obtained from Brownian dynamics with excluded volume interactions.

  2. Imaging Molecular Motion: Femtosecond X-Ray Scattering of an Electrocyclic Chemical Reaction

    Science.gov (United States)

    Minitti, M. P.; Budarz, J. M.; Kirrander, A.; Robinson, J. S.; Ratner, D.; Lane, T. J.; Zhu, D.; Glownia, J. M.; Kozina, M.; Lemke, H. T.; Sikorski, M.; Feng, Y.; Nelson, S.; Saita, K.; Stankus, B.; Northey, T.; Hastings, J. B.; Weber, P. M.

    2015-06-01

    Structural rearrangements within single molecules occur on ultrafast time scales. Many aspects of molecular dynamics, such as the energy flow through excited states, have been studied using spectroscopic techniques, yet the goal to watch molecules evolve their geometrical structure in real time remains challenging. By mapping nuclear motions using femtosecond x-ray pulses, we have created real-space representations of the evolving dynamics during a well-known chemical reaction and show a series of time-sorted structural snapshots produced by ultrafast time-resolved hard x-ray scattering. A computational analysis optimally matches the series of scattering patterns produced by the x rays to a multitude of potential reaction paths. In so doing, we have made a critical step toward the goal of viewing chemical reactions on femtosecond time scales, opening a new direction in studies of ultrafast chemical reactions in the gas phase.

  3. Conception and synthesis of new molecular cages for xenon MRI applications

    International Nuclear Information System (INIS)

    Delacour, L.

    2011-01-01

    Non-invasive proton magnetic resonance imaging ( 1 H MRI) is a powerful clinical tool for the detection of numerous diseases. Although MRI contrast agents are often used to improve diagnostic specificity, this technique has limited applications in molecular imaging because of its inherently low sensitivity when compared to nuclear medicine or fluorescence imaging. Laser-polarized 129 Xe NMR spectroscopy is a promising tool to circumvent sensitivity limitations. Indeed, optical pumping increases the nuclear spin polarization of xenon by several orders of magnitude (10 4 to 10 5 ), thus small amounts of gas dissolved in biological tissues (blood, lungs...) can be rapidly detected with an excellent signal-to-noise ratio. In addition, the high polarizability of the xenon electron cloud, which induces a very high sensitivity to its environment, makes this nucleus very attractive for molecular imaging. Detection of biomolecules can be achieved by biosensors, which encapsulate xenon atoms in molecular cages that have been functionalized to bind the desired biological target. Cage molecules such as cryptophanes have high affinity for xenon and thus appear as ideal candidates for its encapsulation. During this PhD thesis we worked on the synthesis and the functionalization of new cryptophanes. (author) [fr

  4. New Diethyl Ammonium Salt of Thiobarbituric Acid Derivative: Synthesis, Molecular Structure Investigations and Docking Studies

    Directory of Open Access Journals (Sweden)

    Assem Barakat

    2015-11-01

    Full Text Available The synthesis of the new diethyl ammonium salt of diethylammonium(E-5-(1,5-bis(4-fluorophenyl-3-oxopent-4-en-1-yl-1,3-diethyl-4,6-dioxo-2-thioxohexaydropyrimidin-5-ide 3 via a regioselective Michael addition of N,N-diethylthiobarbituric acid 1 to dienone 2 is described. In 3, the carboanion of the thiobarbituric moiety is stabilized by the strong intramolecular electron delocalization with the adjacent carbonyl groups and so the reaction proceeds without any cyclization. The molecular structure investigations of 3 were determined by single-crystal X-ray diffraction as well as DFT computations. The theoretically calculated (DFT/B3LYP geometry agrees well with the crystallographic data. The effect of fluorine replacement by chlorine atoms on the molecular structure aspects were investigated using DFT methods. Calculated electronic spectra showed a bathochromic shift of the π-π* transition when fluorine is replaced by chlorine. Charge decomposition analyses were performed to study possible interaction between the different fragments in the studied systems. Molecular docking simulations examining the inhibitory nature of the compound show an anti-diabetic activity with Pa (probability of activity value of 0.229.

  5. Investigation of the role of NaBH4 in the chemical synthesis of gold nanorods

    International Nuclear Information System (INIS)

    Samal, Akshaya K.; Sreeprasad, Theruvakkattil S.; Pradeep, Thalappil

    2010-01-01

    An improvement in the previously reported seed-mediated chemical synthesis of gold nanorods (GNRs) is reported. Monodisperse GNRs have been synthesized in a one-step protocol. The addition of controlled quantity of sodium borohydride (NaBH 4 ) directly into the growth solution produced uniform GNRs, formed by in situ nucleation and growth. In order to arrive at the conclusion, we studied the formation of GNRs with various seeds, of metals of widely differing crystal structures, and there were no variations in the properties of the GNRs formed. The role of NaBH 4 in the growth of GNR, which has not been covered in previous reports, is discussed in detail. The dependence of longitudinal plasmon peak on the concentration of NaBH 4 is compared with the dependence of residual concentration of NaBH 4 in the seed solution, which is added to the growth solution in seed-mediated synthesis. The study shows that NaBH 4 plays an important role in the formation of GNRs. This proposed protocol offers a number of advantages: one-step preparation of GNRs, significant reduction in the preparation time to 10 min, high monodispersity of GNRs, and tailorability of the aspect ratio depending on NaBH 4 concentration. It is suggested that NaBH 4 added to the growth solution leads to in situ formation of the seed particles of the size of 3-5 nm which enables the growth of GNRs. The growth of GNRs suggested here is likely to have an impact on the preparation of other anisotropic structures. Our single-pot methodology makes the procedure directly adaptable for commercial-scale production of GNRs and for their synthesis even in undergraduate laboratories.

  6. Bio-electrochemical synthesis of commodity chemicals by autotrophic acetogens utilizing CO2 for environmental remediation.

    Science.gov (United States)

    Jabeen, Gugan; Farooq, Robina

    2016-09-01

    Bio-electrochemical synthesis (BES) is a technique in which electro-autotrophic bacteria such as Clostridium ljungdahlii utilize electric currents as an electron source from the cathode to reduce CO2 to extracellular, multicarbon, exquisite products through autotrophic conversion. The BES of volatile fatty acids and alcohols directly from CO2 is a sustainable alternative for non-renewable, petroleum-based polymer production. This conversion of CO2 implies reduction of greenhouse gas emissions. The synthesis of heptanoic acid, heptanol, hexanoic acid and hexanol, for the first time, by Clostridium ljungdahlii was a remarkable achievement of BES. In our study, these microorganisms were cultivated on the cathode of a bio-electrochemical cell at -400 mV by a DC power supply at 37 degree Centrigrade, pH 6.8, and was studied for both batch and continuous systems. Pre-enrichment of bio-cathode enhanced the electroactivity of cells and resulted in maximizing extracellular products in less time. The main aim of the research was to investigate the impact of low-cost substrate CO2, and the longer cathode recovery range was due to bacterial reduction of CO2 to multicarbon chemical commodities with electrons driven from the cathode. Reactor design was simplified for cost-effectiveness and to enhance energy efficiencies. The Columbic recovery of ethanoic acid, ethanol, ethyl butyrate, hexanoic acid, heptanoic acid and hexanol being in excess of 80 percent proved that BES was a remarkable technology.

  7. Chemical synthesis, characterization and evaluation of antimicrobial properties of Cu and its oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moshalagae Motlatle, Abesach, E-mail: AMotlatle@csir.co.za; Kesavan Pillai, Sreejarani, E-mail: skpillai@csir.co.za; Rudolf Scriba, Manfred, E-mail: MRscriba@csir.co.za; Sinha Ray, Suprakas, E-mail: Rsuprakas@csir.co.za [Council for Scientific and Industrial Research, DST/CSIR Nanotechnology Innovation Centre, National Centre for Nano-Structured Materials (South Africa)

    2016-10-15

    Cu nanoparticles were synthesized using low-temperature aqueous reduction method at pH 3, 5, 7, 9 and 11 in presence of ascorbic acid and polyvinylpyrrolidone. The nanoparticles were characterized using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. Results demonstrated a strong dependence of synthesis pH on the size, shape, chemical composition and structure of Cu nanoparticles. While lower pH conditions of 3 and 5 produced Cu{sup 0}, higher pH levels (more than 7) led to the formation of Cu{sub 2}O/CuO nanoparticles. The reducing capacity of ascorbic acid, capping efficiency of PVP and the resulting particle sizes were strongly affected by solution pH. The results of in vitro disk diffusion tests showed excellent antimicrobial activity of Cu{sub 2}O/CuO nanoparticles against a mixture of bacterial strains (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa), indicating that the size as well as oxidation state of Cu contributes to the antibacterial efficacy. The results indicate that varying synthesis pH is a strategy to tailor the composition, structure and properties of Cu nanoparticles.

  8. Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns

    Science.gov (United States)

    Zhang, Chentao; Zhang, Jianhuan; Lin, Kun; Huang, Yuanqing

    2017-05-01

    An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

  9. Copper nanoparticles mediated by chitosan: synthesis and characterization via chemical methods.

    Science.gov (United States)

    Usman, Muhammad Sani; Ibrahim, Nor Azowa; Shameli, Kamyar; Zainuddin, Norhazlin; Yunus, Wan Md Zin Wan

    2012-12-14

    Herein we report a synthesis of copper nanoparticles (Cu-NPs) in chitosan (Cts) media via a chemical reaction method. The nanoparticles were synthesized in an aqueous solution in the presence of Cts as stabilizer and CuSO(4)·5H(2)O precursor. The synthesis proceeded with addition of NaOH as pH moderator, ascorbic acid as antioxidant and hydrazine( )as the reducing agent. The characterization of the prepared NPs was done using ultraviolet-visible spectroscopy, which showed a 593 nm copper band. The Field Emission Scanning Electron Microscope (FESEM) images were also observed, and found to be in agreement with the UV-Vis result, confirming the formation of metallic Cu-NPs. The mean size of the Cu-NPs was estimated to be in the range of 35-75 nm using X-ray diffraction. XRD was also used in analysis of the crystal structure of the NPs. The interaction between the chitosan and the synthesized NPs was studied using Fourier transform infrared (FT-IR) spectroscopy, which showed the capping of the NPs by Cts.

  10. Properties, synthesis, and growth mechanisms of carbon nanotubes with special focus on thermal chemical vapor deposition.

    Science.gov (United States)

    Nessim, Gilbert D

    2010-08-01

    Carbon nanotubes (CNTs) have been extensively investigated in the last decade because their superior properties could benefit many applications. However, CNTs have not yet made a major leap into industry, especially for electronic devices, because of fabrication challenges. This review provides an overview of state-of-the-art of CNT synthesis techniques and illustrates their major technical difficulties. It also charts possible in situ analyses and new reactor designs that might enable commercialization. After a brief description of the CNT properties and of the various techniques used to synthesize substrate-free CNTs, the bulk of this review analyzes chemical vapor deposition (CVD). This technique receives special attention since it allows CNTs to be grown in predefined locations, provides a certain degree of control of the types of CNTs grown, and may have the highest chance to succeed commercially. Understanding the primary growth mechanisms at play during CVD is critical for controlling the properties of the CNTs grown and remains the major hurdle to overcome. Various factors that influence CNT growth receive a special focus: choice of catalyst and substrate materials, source gases, and process parameters. This review illustrates important considerations for in situ characterization and new reactor designs that may enable researchers to better understand the physical growth mechanisms and to optimize the synthesis of CNTs, thus contributing to make carbon nanotubes a manufacturing reality.

  11. Ultrasonic-assisted chemical reduction synthesis and structural characterization of copper nanoparticles

    Science.gov (United States)

    Anh-Nga, Nguyen T.; Tuan-Anh, Nguyen; Thanh-Quoc, Nguyen; Ha, Do Tuong

    2018-04-01

    Copper nanoparticles, due to their special properties, small dimensions and low-cost preparation, have many potential applications such as in optical, electronics, catalysis, sensors, antibacterial agents. In this study, copper nanoparticles were synthesized by chemical reduction method with different conditions in order to investigate the optimum conditions which gave the smallest (particle diameter) dimensions. The synthesis step used copper (II) acetate salt as precursor, ascorbic acid as reducing agent, glycerin and polyvinylpyrrolidone (PVP) as protector and stabilizer. The assistance of ultrasonic was were considered as the significant factor affecting the size of the synthesized particles. The results showed that the copper nanoparticles have been successfully synthesized with the diameter as small as 20-40 nm and the conditions of ultrasonic waves were 48 kHz of frequency, 20 minutes of treated time and 65-70 °C of temperature. The synthesized copper nanoparticles were characterized by optical absorption spectrum, scanning electron microscopy (SEM), and Fourier Transform Infrared Spectrometry.

  12. Synthesis of Nickel and Nickel Hydroxide Nano powders by Simplified Chemical Reduction

    International Nuclear Information System (INIS)

    Tientong, J.; Garcia, S.; Thurber, C.R.; Golden, T.D.

    2014-01-01

    Nickel nano powders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at ph ∼ 12.5. Sonication of the solutions created a temperature of 54-65 °C to activate the reduction reaction of nickel nanoparticles. The solution ph affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (ph ∼10) of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.

  13. Chemical synthesis and structure elucidation of bovine κ-casein (1-44)

    International Nuclear Information System (INIS)

    Bansal, Paramjit S.; Grieve, Paul A.; Marschke, Ronald J.; Daly, Norelle L.; McGhie, Emily; Craik, David J.; Alewood, Paul F.

    2006-01-01

    The caseins (α s1 , α s2 , β, and κ) are phosphoproteins present in bovine milk that have been studied for over a century and whose structures remain obscure. Here we describe the chemical synthesis and structure elucidation of the N-terminal segment (1-44) of bovine κ-casein, the protein which maintains the micellar structure of the caseins. κ-Casein (1-44) was synthesised by highly optimised Boc solid-phase peptide chemistry and characterised by mass spectrometry. Structure elucidation was carried out by circular dichroism and nuclear magnetic resonance spectroscopy. CD analysis demonstrated that the segment was ill defined in aqueous medium but in 30% trifluoroethanol it exhibited considerable helical structure. Further, NMR analysis showed the presence of a helical segment containing 26 residues which extends from Pro 8 to Arg 34 . This is First report which demonstrates extensive secondary structure within the casein class of proteins

  14. Chemical synthesis, redox transformation, and identification of sonnerphenolic C, an antioxidant in Acer nikoense.

    Science.gov (United States)

    Iwadate, Takehiro; Nihei, Ken-Ichi

    2017-04-15

    Sonnerphenolic C (3), which was predicted in a redox product of epirhododendrin (1) isolated from Acer nikoense, was synthesized for the first time via the epimeric separation of benzylidene acetal intermediates as a key step. From a similar synthetic route, 1 was obtained concisely. As a result of their antioxidative evaluation, only 3 revealed potent activity. The redox transformation of 1 into 3 was achieved in the presence of tyrosinase and vitamin C. Moreover, 3 was identified in the decoction of A. nikoense by HPLC analysis with the effective use of synthesized 3. Thus, a novel naturally occurring antioxidant 3 was developed through the sequential flow including redox prediction, chemical synthesis, evaluation of the activity, and identification as the natural product. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Room temperature chemical synthesis of lead selenide thin films with preferred orientation

    Science.gov (United States)

    Kale, R. B.; Sartale, S. D.; Ganesan, V.; Lokhande, C. D.; Lin, Yi-Feng; Lu, Shih-Yuan

    2006-11-01

    Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH3COO)2 as Pb2+ and Na2SeSO3 as Se2- ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.

  16. Room temperature chemical synthesis of lead selenide thin films with preferred orientation

    Energy Technology Data Exchange (ETDEWEB)

    Kale, R.B. [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043 (China)]. E-mail: rb_kale@yahoo.co.in; Sartale, S.D. [Hahn Meitner Institute, Glienicker Strasse-100, D-14109 Berlin (Germany); Ganesan, V. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India); Lokhande, C.D. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Lin, Y.-F. [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043 (China); Lu, S.-Y. [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043 (China)]. E-mail: sylu@mx.nthu.edu.tw

    2006-11-15

    Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH{sub 3}COO){sub 2} as Pb{sup 2+} and Na{sub 2}SeSO{sub 3} as Se{sup 2-} ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.

  17. Size-controlled Synthesis and Characterization of Fe3O4 Nanoparticles by Chemical Coprecipitation Method

    International Nuclear Information System (INIS)

    Chia Chin Hua; Sarani Zakaria; Farahiyan, R.; Liew Tze Khong; Mustaffa Abdullah; Sahrim Ahmad; Nguyen, K.L.

    2008-01-01

    Magnetite (Fe 3 O 4 ) nanoparticles have been synthesized using the chemical coprecipitation method. The Fe 3 O 4 nanoparticles were likely formed via dissolution-recrystallization process. During the precipitation process, ferrihydrite and Fe(OH) 2 particles formed aggregates and followed by the formation of spherical Fe 3 O 4 particles. The synthesized Fe 3 O 4 nanoparticles exhibited superparamagnetic behavior and in single crystal form. The synthesis temperature and the degree of agitation during the precipitation were found to be decisive in controlling the crystallite and particle size of the produced Fe 3 O 4 nanoparticles. Lower temperature and higher degree of agitation were the favorable conditions for producing smaller particle. The magnetic properties (saturation magnetization and coercivity) of the Fe 3 O 4 nanoparticles increased with the particle size. (author)

  18. Alternative chemical-based synthesis routes and characterization of nano-scale particles

    International Nuclear Information System (INIS)

    Brocchi, E.A.; Motta, M.S.; Solorzano, I.G.; Jena, P.K.; Moura, F.J.

    2004-01-01

    Different nano-scale particles have been synthesized by alternative routes: nitrates dehydratation and oxide, or co-formed oxides, reduction by hydrogen. Chemical-based synthesis routes are described and thermodynamics studies and kinetics data are presented to support the feasibility for obtaining single-phase oxides and co-formed two-phase oxides. In addition, the reduction reaction has been applied to successfully produce metal/ceramic nanocomposites. Structural characterization has been carried out by means of X-ray diffraction and, more extensively, transmission electron microscopy operating in conventional diffraction contrast mode (CTEM) and high-resolution mode (HRTEM). Nano-scale size distribution of oxide particles is well demonstrated together with their defect-free structure in the lower range, around 20 nm, size. Structural features related to the synthesized nano-composites are also presented

  19. Room temperature chemical synthesis of lead selenide thin films with preferred orientation

    International Nuclear Information System (INIS)

    Kale, R.B.; Sartale, S.D.; Ganesan, V.; Lokhande, C.D.; Lin, Y.-F.; Lu, S.-Y.

    2006-01-01

    Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH 3 COO) 2 as Pb 2+ and Na 2 SeSO 3 as Se 2- ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV

  20. Quantum chemical density functional theory studies on the molecular structure and vibrational spectra of Gallic acid imprinted polymers

    Science.gov (United States)

    Pardeshi, Sushma; Dhodapkar, Rita; Kumar, Anupama

    2013-12-01

    Gallic acid (GA) is known by its antioxidant, anticarcinogenic properties and scavenger activity against several types of harmful free radicals. Molecularly imprinted polymers (MIPs) are used in separation of a pure compound from complex matrices. A stable template-monomer complex generates the MIPs with the highest affinity and selectivity for the template. The quantum chemical computations based on density functional theory (DFT) was used on the template Gallic acid (GA), monomer acrylic acid (AA) and GA-AA complex to study the nature of interactions involved in the GA-AA complex. B3LYP/6-31+G(2d,2p) model chemistry was used to optimize their structures and frequency calculations. The effect of porogen acetonitrile (ACN) on complex formation was included by using polarizable continuum model (PCM). The results demonstrated the formation of a stable GA-AA complex through the intermolecular hydrogen bonding between carboxylic acid groups of GA and AA. The Mulliken atomic charge analysis and simulated vibrational spectra also supported the stable hydrogen bonding interaction between the carboxylic acid groups of GA and AA with minimal interference of porogen ACN. Further, simulations on GA-AA mole ratio revealed that 1:4 GA-AA was optimum for synthesis of MIP for GA.

  1. Molecular structure, vibrational spectra and quantum chemical MP2/DFT studies toward the rational design of hydroxyurea imprinted polymer

    Science.gov (United States)

    Prasad, Bhim Bali; Rai, Garima

    2013-03-01

    In this study, both experimental and theoretical vibrational spectra of template (hydroxyurea, HU), monomer (N-(4,6-bisacryloyl amino-[1,3,5] triazine-2-yl-)-acryl amide, TAT), and HU-TAT complexes were compared and these were respectively found to be in good agreement. Binding energies of HU, when complexed with different monomers, were computed using second order Moller Plesset theory (MP2) at 6-311++G(d,p) level both in the gas as well as solution phases. HU is an antineoplastic agent extensively being used in the treatment of polycythaemia Vera and thrombocythemia. It is also used to reduce the frequency of painful attacks in sickle cell anemia. It has antiretroviral property in disease like AIDS. All spectral characterizations were made using Density Functional Theory (DFT) at B3LYP employing 6-31+g(2d, 2p) basis set. The theoretical values for 13C and 1H NMR chemical shifts were found to be in accordance with the corresponding experimental values. Of all different monomers studied for the synthesis of molecularly imprinted polymer (MIP) systems, the monomer TAT (2 mol) was typically found to have a best binding score requisite for complexation with HU (1 mol) at the ground state.

  2. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    Science.gov (United States)

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

  3. The New Mars Synthesis: A New Concept Of Mars Geo-Chemical History

    Science.gov (United States)

    Brandenburg, J. E.

    2005-02-01

    A new concept of Mars climatic and geo-chemical evolution is proposed, called the NMS (New Mars Synthesis) drawing on the full spectrum of available Mars data. The proposed synthesis is that Mars and Earth, having begun with similar surface conditions, did not strongly diverge from their similar paths 4.0 Billion years ago, in the Early Noachian, instead, under the NMS, they diverged much more recently in geologic time, in the Early Amazonian. Under the NMS, biology strongly affected the geo-chemical evolution of Mars, and allowed a stable and persistent greenhouse by producing a large oxygen component in the atmosphere. The NMS assumes Mars held biology form early on, has been geologically active throughout its history, that it had a northern paleo-ocean, that it has high, approximately, 4xLunar, cratering rates and that its climate changed recently in geologic time from being basically terrestrial to its present conditions. The proposed mechanism for the stability of the Mars greenhouse was a large oxygen component in the atmosphere that created acidic and highly oxidized conditions that prevented formation of Carbonates, and the thermal and gas buffering of the paleo-ocean. The greenhouse was thus biologically and hydrologically stabilized. The greenhouse was terminated by a large atmospheric cooling event in the Early Amazonian that killed the biosphere and froze the ocean stabilizing the greenhouse. This cooling event was probably caused by the formation of the Lyot impact basin. Given the long duration of this terrestrial biosphere in this NMS, the possible appearance of fossils in some rover images is not to be unexpected and the colonization of Mars by humanity may be aided extensive fossil biomass to use as raw material.

  4. Modified chemical synthesis of porous α-Sm{sub 2}S{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumbhar, V.S.; Jagadale, A.D. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur, (M.S.) 416004 (India); Gaikwad, N.S. [Rayat Shikshan Sanstha, Satara, (M.S.) 415 001 (India); Lokhande, C.D., E-mail: l_chandrakant@yahoo.com [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur, (M.S.) 416004 (India)

    2014-08-15

    Highlights: • A novel chemical route to prepare α-Sm{sub 2}S{sub 3} thin films. • A porous honeycomb like morphology of the α-Sm{sub 2}S{sub 3} thin film. • An application of α-Sm{sub 2}S{sub 3} thin film toward its supercapacitive behaviour. - Abstract: The paper reports synthesis of porous α-Sm{sub 2}S{sub 3} thin films using modified chemical synthesis, also known as successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), wettability and ultraviolet–visible spectroscopy (UV–vis) techniques are used for the study of structural, elemental, morphological and optical properties of α-Sm{sub 2}S{sub 3} films. An orthorhombic crystal structure of α-Sm{sub 2}S{sub 3} is resulted from XRD study. The SEM and AFM observations showed highly porous α-Sm{sub 2}S{sub 3} film surface. An optical band gap of 2.50 eV is estimated from optical absorption spectrum. The porous α-Sm{sub 2}S{sub 3} thin film tuned for supercapacitive behaviour using cyclic voltammetry and galvanostatic charge discharge showed a specific capacitance and energy density of 294 Fg{sup –1} and 48.9 kW kg{sup –1}, respectively in 1 M LiClO{sub 4}–propylene carbonate electrolyte.

  5. Synthesis of carbon nanotubes using the cobalt nanocatalyst by thermal chemical vapor deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Madani, S.S. [Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Zare, K. [Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Department of Chemistry, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Ghoranneviss, M. [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Salar Elahi, A., E-mail: Salari_phy@yahoo.com [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-11-05

    The three main synthesis methods of Carbon nanotubes (CNTs) are the arc discharge, the laser ablation and the chemical vapour deposition (CVD) with a special regard to the latter one. CNTs were produced on a silicon wafer by Thermal Chemical Vapor Deposition (TCVD) using acetylene as a carbon source, cobalt as a catalyst and ammonia as a reactive gas. The DC-sputtering system was used to prepare cobalt thin films on Si substrates. A series of experiments was carried out to investigate the effects of reaction temperature and deposition time on the synthesis of the nanotubes. The deposition time was selected as 15 and 25 min for all growth temperatures. Energy Dispersive X-ray (EDX) measurements were used to investigate the elemental composition of the Co nanocatalyst deposited on Si substrates. Atomic Force Microscopy (AFM) was used to characterize the surface topography of the Co nanocatalyst deposited on Si substrates. The as-grown CNTs were characterized under Field Emission Scanning Electron Microscopy (FESEM) to study the morphological properties of CNTs. Also, the grown CNTs have been investigated by High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. The results demonstrated that increasing the temperature leads to increasing the diameter of CNTs. The ideal reaction temperature was 850 °C and the deposition time was 15 min. - Graphical abstract: FESEM images of CNTs grown on the cobalt catalyst at growth temperatures of (a) 850 °C, (b) 900 °C, (c) 950 °C and (d) 1000 °C during the deposition time of 15 min. - Highlights: • Carbon nanotubes (CNTs) were produced on a silicon wafer by TCVD technique. • EDX and AFM were used to investigate the elemental composition and surface topography. • FESEM was used to study the morphological properties of CNTs. • The grown CNTs have been investigated by HRTEM and Raman spectroscopy.

  6. Chemical recycling of poly(ethylene terephthalate. Application to the synthesis of multiblock copolyesters

    Directory of Open Access Journals (Sweden)

    F. Malek

    2014-08-01

    Full Text Available The chemical recycling of the poly(ethylene terephthalate, (PET, has been successfully carried out by glycolysis in the presence of bis (2-hydroxyethyl terephthalate (BHET resulting in the formation of hydroxytelechelic oligomers. These oligomers were then treated with carboxytelechelic poly(ε-caprolactone oligomers of Mn = 2300 and Mn = 730 g•mol–1 molecular weight, in the absence or presence of the titanium tetrabutyloxide (Ti(OBu4 as a catalyst to get multiblock copolyesters. The chemical structure of the synthesized copolyesters was investigated by size exclusion chromatography (SEC and proton Nuclear Magnetic Resonance (1H NMR spectroscopy. Moreover the differential scanning calorimetry (DSC was used to explore their thermal properties. The ester-ester interchange reaction was observed between the two oligopolyesters, was studied and discussed in detail.

  7. A rapid room temperature chemical route for the synthesis of graphene: metal-mediated reduction of graphene oxide.

    Science.gov (United States)

    Dey, Ramendra Sundar; Hajra, Saumen; Sahu, Ranjan K; Raj, C Retna; Panigrahi, M K

    2012-02-07

    A rapid and facile route for the synthesis of reduced graphene oxide sheets (rGOs) at room temperature by the chemical reduction of graphene oxide using Zn/acid in aqueous solution is demonstrated. This journal is © The Royal Society of Chemistry 2012

  8. Synthesis of lucifensin by native chemical ligation and characteristics of its isomer having different disulfide bridge pattern

    Czech Academy of Sciences Publication Activity Database

    Stanchev, Stancho; Zawada, Zbigniew; Monincová, Lenka; Bednárová, Lucie; Slaninová, Jiřina; Fučík, Vladimír; Čeřovský, Václav

    2014-01-01

    Roč. 20, č. 9 (2014), s. 725-735 ISSN 1075-2617 Institutional support: RVO:61388963 Keywords : lucifensin * native chemical ligation * solid-phase peptide synthesis * antimicrobial activity * CD spectroscopy * DTT reduction Subject RIV: CE - Biochemistry Impact factor: 1.546, year: 2014

  9. Synthesis and molecular characterization of chitosan based polyurethane elastomers using aromatic diisocyanate.

    Science.gov (United States)

    Zia, Khalid Mahmood; Anjum, Sohail; Zuber, Mohammad; Mujahid, Muhammad; Jamil, Tahir

    2014-05-01

    The present research work was performed to synthesize a new series of chitosan based polyurethane elastomers (PUEs) using poly(ɛ-caprolactone) (PCL). The chitosan based PUEs were prepared by step-growth polymerization technique using poly(ɛ-caprolactone) (PCL) and 2,4-toluene diisocyanate (TDI). In the second step the PU prepolymer was extended with different mole ratios of chitosan and 1,4-butane diol (BDO). Molecular engineering was carried out during the synthesis. The conventional spectroscopic characterization of the synthesized samples using FT-IR confirms the existence of the proposed chitosan based PUEs structure. Internal morphology of the prepared PUEs was studied using SEM analysis. The SEM images confirmed the incorporation of chitosan molecules into the PU backbone. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Synthesis, characterization, and catalytic properties of stable mesoporous molecular sieve MCM-41 prepared from zeolite mordenite

    International Nuclear Information System (INIS)

    Wang Shan; Dou Tao; Li Yuping; Zhang Ying; Li Xiaofeng; Yan Zichun

    2004-01-01

    Mesoporous molecular sieves (denoted as M-MCM-41) with ordered hexagonal structure have been successfully synthesized from the assembly of precursors from preformed zeolite Mordenite with CTAB surfactant micelle in alkaline media. The samples were characterized by XRD, N 2 adsorption, IR and DTG. The materials exhibit highly hydrothermal stability, as compared with conventional MCM-41. Characterization results indicate that the mesoporous walls of M-MCM-41 contain the secondary building units similar to those in microporous crystal of zeolite Mordenite. In catalytic dealkylation of C10 + aromatic hydrocarbon, M-MCM-41 shows higher activities in comparison with Mordenite and MCM-41, which would be ascribed to the combination of advantages of both MCM-41 (large pores) and Mordenite (strong acidity). Furthermore, this synthesis strategy could be used as a new general method for the preparation of hydrothermally stable mesoporous aluminosilicate materials under alkaline conditions

  11. Synthesis and analytical applications of molecularly imprinted polymers on the surface of carbon nanotubes: a review

    International Nuclear Information System (INIS)

    Dai, Hao; Xiao, Deli; Li, Hui; Yuan, Danhua; Zhang, Chan; He, Hua

    2015-01-01

    This review (with 142 references) summarize the state of the art in molecularly imprinting technology as applied to the surface of carbon nanotubes (CNTs) which result in so-called CNTs-MIPs. These nanomaterials offer a remedy to the flaws of traditional MIPs, such as poor site accessibility for templates, slow mass transfer and template leakage. They also are flexible in that different materials can be integrated with CNTs. Given the advantages of using CNT-MIPs, this technology has experienced rapid expansion, not the least because CNT-MIPs can be produced at low cost and by a variety of synthetic approaches. We summarize methods of, and recent advances in the synthesis of CNT-MIPs, and then highlight some representative applications. We also comment on their potential future developments and research directions. (author)

  12. Molecular hijacking of siroheme for the synthesis of heme and d1 heme.

    Science.gov (United States)

    Bali, Shilpa; Lawrence, Andrew D; Lobo, Susana A; Saraiva, Lígia M; Golding, Bernard T; Palmer, David J; Howard, Mark J; Ferguson, Stuart J; Warren, Martin J

    2011-11-08

    Modified tetrapyrroles such as chlorophyll, heme, siroheme, vitamin B(12), coenzyme F(430), and heme d(1) underpin a wide range of essential biological functions in all domains of life, and it is therefore surprising that the syntheses of many of these life pigments remain poorly understood. It is known that the construction of the central molecular framework of modified tetrapyrroles is mediated via a common, core pathway. Herein a further branch of the modified tetrapyrrole biosynthesis pathway is described in denitrifying and sulfate-reducing bacteria as well as the Archaea. This process entails the hijacking of siroheme, the prosthetic group of sulfite and nitrite reductase, and its processing into heme and d(1) heme. The initial step in these transformations involves the decarboxylation of siroheme to give didecarboxysiroheme. For d(1) heme synthesis this intermediate has to undergo the replacement of two propionate side chains with oxygen functionalities and the introduction of a double bond into a further peripheral side chain. For heme synthesis didecarboxysiroheme is converted into Fe-coproporphyrin by oxidative loss of two acetic acid side chains. Fe-coproporphyrin is then transformed into heme by the oxidative decarboxylation of two propionate side chains. The mechanisms of these reactions are discussed and the evolutionary significance of another role for siroheme is examined.

  13. Chemical-induced coordinated and reciprocal changes in heme metabolism, cytochrome P450 synthesis and others in the liver of humans and rodents.

    Science.gov (United States)

    Yoshida, Takemi; Ashino, Takashi; Kobayashi, Yasuna

    2016-01-01

    A wide variety of drugs and chemicals have been shown to produce induction and inhibition of heme-metabolizing enzymes, and of drug-metabolizing enzymes, including cytochrome P450s (P450s, CYPs), which consist of many molecular species with lower substrate specificity. Such chemically induced enzyme alterations are coordinately or reciprocally regulated through the same and/or different signal transductions. From the toxicological point of view, these enzymatic changes sometimes exacerbate inherited diseases, such as precipitation of porphyrogenic attacks, although the induction of these enzymes is dependent on the animal species in response to the differences in the stimuli of the liver, where they are also metabolized by P450s. Since P450s are hemoproteins, their induction and/or inhibition by chemical compounds could be coordinately accompanied by heme synthesis and/or inhibition. This review will take a retrospective view of research works carried out in our department and current findings on chemical-induced changes in hepatic heme metabolism in many places, together with current knowledge. Specifically, current beneficial aspects of induction of heme oxygenase-1, a rate-limiting heme degradation enzyme, and its relation to reciprocal and coordinated changes in P450s, with special reference to CYP2A5, in the liver are discussed. Mechanistic studies are also summarized in relation to current understanding on these aspects. Emphasis is also paid to an example of a single chemical compound that could cause various changes by mediating multiple signal transduction systems. Current toxicological studies have been developing by utilizing a sophisticated "omics" technology and survey integrated changes in the tissues produced by the administration of a chemical, even in time- and dose-dependent manners. Toxicological studies are generally carried out step by step to determine and elucidate mechanisms produced by drugs and chemicals. Such approaches are correct

  14. Molecular dynamics investigations of BioH protein substrate specificity for biotin synthesis.

    Science.gov (United States)

    Xue, Qiao; Cui, Ying-Lu; Zheng, Qing-Chuan; Zhang, Hong-Xing

    2016-05-01

    BioH, an enzyme of biotin synthesis, plays an important role in fatty acid synthesis which assembles the pimelate moiety. Pimeloyl-acyl carrier protein (ACP) methyl ester, which is long known to be a biotin precursor, is the physiological substrate of BioH. Azelayl methyl ester, which has a longer chain than pimeloyl methyl ester, conjugated to ACP is also indeed accepted by BioH with very low rate of hydrolysis. To date, the substrate specificity for BioH and the molecular origin for the experimentally observed rate changes of hydrolysis by the chain elongation have remained elusive. To this end, we have investigated chain elongation effects on the structures by using the fully atomistic molecular dynamics simulations combined with binding free energy calculations. The results indicate that the substrate specificity is determined by BioH together with ACP. The added two methylenes would increase the structural flexibility by protein motions at the interface of ACP and BioH, instead of making steric clashes with the side chains of the BioH hydrophobic cavity. On the other hand, the slower hydrolysis of azelayl substrate is suggested to be associated with the loose of contacts between BioH and ACP, and with the lost electrostatic interactions of two ionic/hydrogen bonding networks at the interface of the two proteins. The present study provides important insights into the structure-function relationships of the complex of BioH with pimeloyl-ACP methyl ester, which could contribute to further understanding about the mechanism of the biotin synthetic pathway, including the catalytic role of BioH.

  15. Molecular structure, vibrational analysis (IR and Raman) and quantum chemical investigations of 1-aminoisoquinoline

    Science.gov (United States)

    Sivaprakash, S.; Prakash, S.; Mohan, S.; Jose, Sujin P.

    2017-12-01

    Quantum chemical calculations of energy and geometrical parameters of 1-aminoisoquinoline [1-AIQ] were carried out by using DFT/B3LYP method using 6-311G (d,p), 6-311G++(d,p) and cc-pVTZ basis sets. The vibrational wavenumbers were computed for the energetically most stable, optimized geometry. The vibrational assignments were performed on the basis of potential energy distribution (PED) using VEDA program. The NBO analysis was done to investigate the intra molecular charge transfer of the molecule. The frontier molecular orbital (FMO) analysis was carried out and the chemical reactivity descriptors of the molecule were studied. The Mulliken charge analysis, molecular electrostatic potential (MEP), HOMO-LUMO energy gap and the related properties were also investigated at B3LYP level. The absorption spectrum of the molecule was studied from UV-Visible analysis by using time-dependent density functional theory (TD-DFT). Fourier Transform Infrared spectrum (FT-IR) and Raman spectrum of 1-AIQ compound were analyzed and recorded in the range 4000-400 cm-1 and 3500-100 cm-1 respectively. The experimentally determined wavenumbers were compared with those calculated theoretically and they complement each other.

  16. Molecular and multiscale modeling: review on the theories and applications in chemical engineering

    International Nuclear Information System (INIS)

    Morales M, Giovanni; Martinez R, Ramiro

    2010-01-01

    We call molecular modeling to the application of suitable laws in the analysis of phenomena occurred at scales less than those accounted for by the macroscopic world. Such different scales (including micro-, meso- and macro scales), can be linked and integrated in order to improve understanding and predictions of complex physical chemistry phenomena, thus originating a global or multi scale analysis. A considerable amount of chemical engineering phenomena are complex due to the interrelation among these different realms of length and time. Multi scale modeling rises as an alternative for an outstanding mathematical and conceptual representation of such phenomena. This adequate representation may help to design and optimize chemical and petrochemical processes from a microscopic point of view. Herein we present a brief introduction to both molecular and multi scale modeling methods. We also comment and examine opportunities for applying the different levels of modeling to the analysis of industrial problems. The fundamental mathematical machinery of the molecular modelling theories is presented in order to motivate the study of these new engineering tools. Finally, we show a classification of different strategies for applying multilevel analysis, illustrating various examples of each methodology.

  17. The Role of Molecular Biology in the Biomonitoring of Human Exposure to Chemicals

    Directory of Open Access Journals (Sweden)

    Balam Muñoz

    2010-11-01

    Full Text Available Exposure to different substances in an occupational environment is of utmost concern to global agencies such as the World Health Organization and the International Labour Organization. Interest in improving work health conditions, particularly of those employees exposed to noxious chemicals, has increased considerably and has stimulated the search for new, more specific and selective tests. Recently, the field of molecular biology has been indicated as an alternative technique for monitoring personnel while evaluating work-related pathologies. Originally, occupational exposure to environmental toxicants was assessed using biochemical techniques to determine the presence of higher concentrations of toxic compounds in blood, urine, or other fluids or tissues; results were used to evaluate potential health risk. However, this approach only estimates the presence of a noxious chemical and its effects, but does not prevent or diminish the risk. Molecular biology methods have become very useful in occupational medicine to provide more accurate and opportune diagnostics. In this review, we discuss the role of the following common techniques: (1 Use of cell cultures; (2 evaluation of gene expression; (3 the “omic” sciences (genomics, transcriptomics, proteomics and metabolomics and (4 bioinformatics. We suggest that molecular biology has many applications in occupational health where the data can be applied to general environmental conditions.

  18. Molecular Mobility of an Amorphous Chiral Pharmaceutical Compound: Impact of Chirality and Chemical Purity.

    Science.gov (United States)

    Viel, Quentin; Delbreilh, Laurent; Coquerel, Gérard; Petit, Samuel; Dargent, Eric

    2017-08-17

    A dielectric relaxation spectroscopy (DRS) study was performed to investigate the molecular mobility of amorphous chiral diprophylline (DPL). For this purpose, both racemic DPL and a single enantiomer of DPL were considered. After fast cooling from the melt at very low temperature (-140 °C), progressive heating below and above the glass transition (T g ≈ 37 °C) induces two secondary relaxations (γ- and δ-) and primary relaxations (α-) for both enantiomeric compositions. After chemical purification of our samples by means of cooling recrystallization, no γ-process could be detected by DRS. Hence, it was highlighted that the molecular mobility in the glassy state is influenced by the presence of theophylline (TPH), the main impurity in DPL samples. We also proved that the dynamic behavior of a single enantiomer and the racemic mixture of the same purified compound are quasi-identical. This study demonstrates that the relative stability and the molecular mobility of chiral amorphous drugs are strongly sensitive to chemical purity.

  19. EXPLORING THE DESIGN AND USE OF MOLECULAR ANIMATIONS THAT CONFLICT FOR UNDERSTANDING CHEMICAL REACTIONS

    Directory of Open Access Journals (Sweden)

    Resa M. Kelly

    Full Text Available Understanding chemical reactions conceptually involves recognizing characteristics of observable phenomena and envisioning how atoms, ions and molecules move and interact to cause the macroscopic changes. Our research focuses on the development of effective strategies for designing and presenting visualizations (videos and animations to assist students with making connections between macroscopic and molecular level behaviors of chemical reactions. Specifically, we study how students, who view videos of a redox reaction that exhibits obvious signs of macroscopic chemical change, can determine which molecular animation of a set of contrasting animations is best supported by its fit with experimental evidence. Herein we describe how we develop our videos and animations, and how students are learning from this animation task. Students who select inaccurate animation models are often enticed by a model that is easier to explain and fits with their understanding of reaction equations. We note that even though students indicate a preference for one animation over another, they often revise their drawn representations to fit with features from multiple animations. With the assistance of eye tracking research, we are gaining a better understanding of what students view and how they make sense of it.

  20. Chemically stabilized reduced graphene oxide/zirconia nanocomposite: synthesis and characterization

    Science.gov (United States)

    Sagadevan, Suresh; Zaman Chowdhury, Zaira; Enamul Hoque, Md; Podder, Jiban

    2017-11-01

    In this research, chemical method was used to fabricate reduced graphene oxide/zirconia (rGO/ZrO2) nanocomposite. X-ray Diffraction analysis (XRD) was carried out to examine the crystalline structure of the nanocomposites. The nanocomposite prepared here has average crystallite size of 14 nm. The surface morphology was observed using scanning electron microscopic analysis (SEM) coupled with electron dispersion spectroscopy (EDS) to detect the chemical element over the surface of the nanocomposites. High-resolution Transmission electron microscopic analysis (HR-TEM) was carried out to determine the particle size and shape of the nanocomposites. The optical property of the prepared samples was determined using UV-visible absorption spectrum. The functional groups were identified using FTIR and Raman spectroscopic analysis. Efficient, cost effective and properly optimized synthesis process of rGO/ZrO2 nanocomposite can ensure the presence of infiltrating graphene network inside the ZrO2 matrix to enhance the electrical properties of the hybrid composites up to a greater scale. Thus the dielectric constant, dielectric loss and AC conductivity of the prepared sample was measured at various frequencies and temperatures. The analytical results obtained here confirmed the homogeneous dispersion of ZrO2 nanostructures over the surface of reduced graphene oxide nanosheets. Overall, the research demonstrated that the rGO/ZrO2 nano-hybrid structure fabricated here can be considered as a promising candidate for applications in nanoelectronics and optoelectronics.

  1. Synthesis of ZnO nanopencils using wet chemical method and its investigation as LPG sensor

    International Nuclear Information System (INIS)

    Shimpi, Navinchandra G.; Jain, Shilpa; Karmakar, Narayan; Shah, Akshara; Kothari, D.C.; Mishra, Satyendra

    2016-01-01

    Highlights: • Synthesis using a simple and cost-effective wet chemical process. • Uniform, monodispersed and pure nanoparticles. • Pencil shaped rods with sharp tips. • Understanding of Growth mechanism. • Efficient LPG sensing with high response. • Morphology dependent sensing. - Abstract: ZnO nanopencils (NPCs) were prepared by a novel wet chemical process, using triethanolamine (TEA) as a mild base, which is relatively simple and cost effective method as compared to hydrothermal method. ZnO NPCs were characterized using powder X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy in mid-IR and far-IR regions, X-ray Photoelectron Spectroscopy (XPS), UV–vis (UV–vis) absorption spectroscopy, room temperature Photoluminescence (PL) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). ZnO NPCs obtained, were highly pure, uniform and monodispersed.XRD pattern indicated hexagonal unit cell structure with preferred orientation along the c-axis. Sensing behaviour of ZnO NPCs was studied towards Liquefied Petroleum Gas (LPG) at different operating temperatures. The study shows that ZnO NPCs were most sensitive and promising candidate for detection of LPG at 250 °C with gas sensitivity > 60%. The high response towards LPG is due to high surface area of ZnO NPCs and their parallel alignment.

  2. Synthesis of ZnO nanopencils using wet chemical method and its investigation as LPG sensor

    Energy Technology Data Exchange (ETDEWEB)

    Shimpi, Navinchandra G., E-mail: navin_shimpi@rediffmail.com [Department of Chemistry, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Jain, Shilpa [Department of Chemistry, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Karmakar, Narayan [Department of Physics, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Shah, Akshara [Department of Chemistry, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Kothari, D.C. [Department of Physics, University of Mumbai, Santacruz (East), Mumbai-400098 (India); National Centre for Nanosciences & Nanotechnology, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Mishra, Satyendra [University Institute of Chemical Technology, North Maharashtra University, Jalgaon (India)

    2016-12-30

    Highlights: • Synthesis using a simple and cost-effective wet chemical process. • Uniform, monodispersed and pure nanoparticles. • Pencil shaped rods with sharp tips. • Understanding of Growth mechanism. • Efficient LPG sensing with high response. • Morphology dependent sensing. - Abstract: ZnO nanopencils (NPCs) were prepared by a novel wet chemical process, using triethanolamine (TEA) as a mild base, which is relatively simple and cost effective method as compared to hydrothermal method. ZnO NPCs were characterized using powder X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy in mid-IR and far-IR regions, X-ray Photoelectron Spectroscopy (XPS), UV–vis (UV–vis) absorption spectroscopy, room temperature Photoluminescence (PL) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). ZnO NPCs obtained, were highly pure, uniform and monodispersed.XRD pattern indicated hexagonal unit cell structure with preferred orientation along the c-axis. Sensing behaviour of ZnO NPCs was studied towards Liquefied Petroleum Gas (LPG) at different operating temperatures. The study shows that ZnO NPCs were most sensitive and promising candidate for detection of LPG at 250 °C with gas sensitivity > 60%. The high response towards LPG is due to high surface area of ZnO NPCs and their parallel alignment.

  3. Chemical synthesis of Fe{sub 2}O{sub 3} thin films for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Kulal, P.M.; Dubal, D.P.; Lokhande, C.D. [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India); Fulari, V.J., E-mail: vijayfulari@gmail.com [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India)

    2011-02-03

    Research highlights: > Simple chemical synthesis of Fe{sub 2}O{sub 3}. > Formation of amorphous and hydrous Fe{sub 2}O{sub 3}. > Potential candidate for supercapacitors. - Abstract: Fe{sub 2}O{sub 3} thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method. Further these films were characterized for their structural, morphological and optical properties by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), wettability test and optical absorption studies. The XRD pattern showed that the Fe{sub 2}O{sub 3} films exhibit amorphous in nature. Formation of iron oxide compound was confirmed from FTIR studies. The optical absorption showed existence of direct optical band gap of energy 2.2 eV. Fe{sub 2}O{sub 3} film surface showed superhydrophilic nature with water contact angle less than 10{sup o}. The supercapacitive properties of Fe{sub 2}O{sub 3} thin film investigated in 1 M NaOH electrolyte showed supercapacitance of 178 F g{sup -1} at scan rate 5 mV/s.

  4. Chemical synthesis of magnetic Fe-B and Fe-Co-B particles and chains

    International Nuclear Information System (INIS)

    Fulmer, P.; Kim, J.; Manthiram, A.; Sanchez, J.M.

    1999-04-01

    With an objective to develop magnetic materials with high saturation magnetization for the Magnetically Assisted Chemical Separation (MACS) process the chemical synthesis of Fe-B and Fe-Co-B alloys by reducing iron and cobalt chloride solutions with potassium borohydride has been investigated systematically. The influence of the concentration of the reactants, applied magnetic field, reaction atmosphere, and method of mixing the reactants on the microstructure, particle size, composition and magnetic properties has been studied. Both M-B (M = Fe and Co) particles and elongated chains composed of nanometer size M-B particles have been obtained depending on the reaction conditions. The Fe-B samples exhibit saturation magnetization of M S of 120--190 emu/g, remanent magnetization M r of 10--22 emu/g, and coercive field H c of 400--900 Oe. A high M S value of 190 emu/g, which is close to the theoretical value of 218 emu/g for pure Fe, has been achieved particularly for samples with well-defined chain structures. Increasing the Co content in the Fe-Co-B alloys increases the boron content and thereby decreases the crystallinity and M S values although marginal increase in H c (1,250 Oe) and M r (36 emu/g) values could be made in some Fe-Co-B compositions. The chain structure with high M S may be attractive for other magnetic separation processes as well

  5. The Synthesis of Silver Nanoparticles Produced by Chemical Reduction of Silver Salt Solution

    International Nuclear Information System (INIS)

    Sri Budi Harmani; Dewi Sondari; Agus Haryono

    2008-01-01

    Described in this research are the synthesis of silver nanoparticle produced by chemical reduction of silver salt (silver nitrate AgNO 3 ) solution. As a reducer, sodium citrate (C 6 H 5 O 7 Na 3 ) was used. Preparation of silver colloid is done by using chemical reduction method. In typical experiment 150 ml of 1.10 -3 M AgNO 3 solution was heated with temperature variation such as 90, 100, 110 degree of Celsius. To this solution 15 ml of 1 % trisodium citrate was added into solution drop by drop during heating. During the process, solution was mixed vigorously. Solution was heated until colour's change is evident (pale yellow solution is formed). Then it was removed from the heating element and stirred until cooled to room temperature. Experimental result showed that diameter of silver nanoparticles in colloid solution is about 28.3 nm (Ag colloid, 90 o C); 19.9 nm (Ag colloid, 100 o C)and 26.4 nm (Ag colloid, 110 o C). Characterization of the silver nanoparticle colloid conducted by using UV-Vis Spectroscopy, Particles Size Analyzer (PSA) and Scanning Electron Microscope (SEM) indicate the produced structures of silver nanoparticles. (author)

  6. Synthesis of Mn3O4 nanoparticles via chemical precipitation approach for supercapacitor application

    International Nuclear Information System (INIS)

    Gnana Sundara Raj, Balasubramaniam; Asiri, Abdullah M.; Wu, Jerry J.; Anandan, Sambandam

    2015-01-01

    Highlights: • Facile synthesis of Mn 3 O 4 nanoparticles at room temperature via simple chemical precipitation method. • Fabricated supercapacitor device shows maximum specific capacitance in 1 M Na 2 SO 4 . • 77% of specific capacitance is retained even after 1000 cycles. - Abstract: A simple chemical precipitation method has been used for the preparation of Mn 3 O 4 nanoparticles at room temperature. The crystal structure and morphology studies of the resulting Mn 3 O 4 nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), N 2 adsorption and desorption and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the Mn 3 O 4 nanoparticles were then investigated using cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS) analysis. The supercapacitive properties of Mn 3 O 4 nanoparticles in the presence of 1 M Na 2 SO 4 exhibited a high specific capacitance of 322 F g −1 at a current density of 0.5 mA cm −2 in the potential range from −0.1 to +0.9 V and about 77% of the initial capacitance was retained after 1000 cycles, indicating that the Mn 3 O 4 electrode owns a good electrochemical stability and capacitance retention capability. The results suggest that the obtained Mn 3 O 4 nanoparticles is a promising electrode material for supercapacitor applications

  7. Chemical synthesis of highly stable PVA/PANI films for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Patil, D.S.; Shaikh, J.S.; Dalavi, D.S.; Kalagi, S.S. [Thin Films Materials laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India); Patil, P.S., E-mail: psp_phy@unishivaji.ac.in [Thin Films Materials laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India)

    2011-08-15

    Highlights: {yields} Chemical synthesis of PVA/PANI films by spin and dip coating at room temperature. {yields} Thickness dependent supercapacitor behavior of PVA/PANI film. {yields} The synthesized film are highly stable up to 20,000 cycles. - Abstract: Polyvinyl alcohol (PVA)/polyaniline (PANI) thin films were chemically synthesized by adopting two step process: initially a thin layer (200 nm) of PVA was spin coated by using an aqueous PVA solution onto fluorine doped tin oxide (FTO) coated glass substrate, afterwards PANI was chemically polymerized from aniline monomer and dip coated onto the precoated substrate. The thickness of PANI layer was varied from 293 nm to 2367 nm by varying deposition cycles onto the precoated PVA thin film. The resultant PVA/PANI films were characterized for their optical, morphological and electrochemical properties. The FT-IR and Raman spectra revealed characteristic features of the PANI phase. The SEM study showed porous spongy structure. Electrochemical properties were studied by electrochemical impedance measurement and cyclic voltammetry. The electrochemical performance of PVA/PANI thin films was investigated in 1 M H{sub 2}SO{sub 4} aqueous electrolyte. The highest specific capacitance of 571 Fg{sup -1} was observed for the optimized thickness of 880 nm. The film was found to be stable for more than 20,000 cycles. The samples degraded slightly (25% decrement in specific capacitance) for the first 10,000 cycles. The degradation becomes much slower (10.8% decrement in specific capacitance) beyond 10,000 cycles. This dramatic improvement in the electrochemical stability of the PANI samples, without sacrificing specific capacitance was attributed to the optimized PVA layer.

  8. Design, synthesis, α-glucosidase inhibitory activity, molecular docking and QSAR studies of benzimidazole derivatives

    Science.gov (United States)

    Dinparast, Leila; Valizadeh, Hassan; Bahadori, Mir Babak; Soltani, Somaieh; Asghari, Behvar; Rashidi, Mohammad-Reza

    2016-06-01

    In this study the green, one-pot, solvent-free and selective synthesis of benzimidazole derivatives is reported. The reactions were catalyzed by ZnO/MgO containing ZnO nanoparticles as a highly effective, non-toxic and environmentally friendly catalyst. The structure of synthesized benzimidazoles was characterized using spectroscopic technics (FT-IR, 1HNMR, 13CNMR). Synthesized compounds were evaluated for their α-glucosidase inhibitory potential. Compounds 3c, 3e, 3l and 4n were potent inhibitors with IC50 values ranging from 60.7 to 168.4 μM. In silico studies were performed to explore the binding modes and interactions between enzyme and synthesized benzimidazoles. Developed linear QSAR model based on density and molecular weight could predict bioactivity of newly synthesized compounds well. Molecular docking studies revealed the availability of some hydrophobic interactions. In addition, the bioactivity of most potent compounds had good correlation with estimated free energy of binding (ΔGbinding) which was calculated according to docked best conformations.

  9. New approaches to the treatment of orphan genetic disorders: Mitigating molecular pathologies using chemicals

    Directory of Open Access Journals (Sweden)

    RENATA V. VELHO

    2015-08-01

    Full Text Available With the advance and popularization of molecular techniques, the identification of genetic mutations that cause diseases has increased dramatically. Thus, the number of laboratories available to investigate a given disorder and the number of subsequent diagnosis have increased over time. Although it is necessary to identify mutations and provide diagnosis, it is also critical to develop specific therapeutic approaches based on this information. This review aims to highlight recent advances in mutation-targeted therapies with chemicals that mitigate mutational pathology at the molecular level, for disorders that, for the most part, have no effective treatment. Currently, there are several strategies being used to correct different types of mutations, including the following: the identification and characterization of translational readthrough compounds; antisense oligonucleotide-mediated splicing redirection; mismatch repair; and exon skipping. These therapies and other approaches are reviewed in this paper.

  10. New approaches to the treatment of orphan genetic disorders: Mitigating molecular pathologies using chemicals.

    Science.gov (United States)

    Velho, Renata V; Sperb-Ludwig, Fernanda; Schwartz, Ida V D

    2015-08-01

    With the advance and popularization of molecular techniques, the identification of genetic mutations that cause diseases has increased dramatically. Thus, the number of laboratories available to investigate a given disorder and the number of subsequent diagnosis have increased over time. Although it is necessary to identify mutations and provide diagnosis, it is also critical to develop specific therapeutic approaches based on this information. This review aims to highlight recent advances in mutation-targeted therapies with chemicals that mitigate mutational pathology at the molecular level, for disorders that, for the most part, have no effective treatment. Currently, there are several strategies being used to correct different types of mutations, including the following: the identification and characterization of translational readthrough compounds; antisense oligonucleotide-mediated splicing redirection; mismatch repair; and exon skipping. These therapies and other approaches are reviewed in this paper.

  11. Molecular Dynamics Study of Thermally Augmented Nanodroplet Motion on Chemical Energy Induced Wettability Gradient Surfaces.

    Science.gov (United States)

    Chakraborty, Monojit; Chowdhury, Anamika; Bhusan, Richa; DasGupta, Sunando

    2015-10-20

    Droplet motion on a surface with chemical energy induced wettability gradient has been simulated using molecular dynamics (MD) simulation to highlight the underlying physics of molecular movement near the solid-liquid interface including the contact line friction. The simulations mimic experiments in a comprehensive manner wherein microsized droplets are propelled by the surface wettability gradient against forces opposed to motion. The liquid-wall Lennard-Jones interaction parameter and the substrate temperature are varied to explore their effects on the three-phase contact line friction coefficient. The contact line friction is observed to be a strong function of temperature at atomistic scales, confirming their experimentally observed inverse functionality. Additionally, the MD simulation results are successfully compared with those from an analytical model for self-propelled droplet motion on gradient surfaces.

  12. Effect on molecular interactions of chemical alteration of petroleum asphaltenes. I

    DEFF Research Database (Denmark)

    Juyal, Priyanka; Garcia, Daniel Merino; Andersen, Simon Ivar

    2005-01-01

    Asphaltenes are naturally occurring components of crude oil and have been the subject of many studies that have involved a variety of methods to determine their complex structure, their association in crude oil with resins, and their agglomeration phenomena. Yet, the molecular structures of aspha......Asphaltenes are naturally occurring components of crude oil and have been the subject of many studies that have involved a variety of methods to determine their complex structure, their association in crude oil with resins, and their agglomeration phenomena. Yet, the molecular structures...... of asphaltenes have not been fully elucidated. It is especially important to characterize the polar functionalities of these fractions, because they participate in the intermolecular aggregation by means of hydrogen bonds. The chemical derivatization of asphaltenes has been used, in combination with suitable...

  13. Molecular design chemical structure generation from the properties of pure organic compounds

    CERN Document Server

    Horvath, AL

    1992-01-01

    This book is a systematic presentation of the methods that have been developed for the interpretation of molecular modeling to the design of new chemicals. The main feature of the compilation is the co-ordination of the various scientific disciplines required for the generation of new compounds. The five chapters deal with such areas as structure and properties of organic compounds, relationships between structure and properties, and models for structure generation. The subject is covered in sufficient depth to provide readers with the necessary background to understand the modeling

  14. Chemical Kinetics for Bridging Molecular Mechanisms and Macroscopic Measurements of Amyloid Fibril Formation.

    Science.gov (United States)

    Michaels, Thomas C T; Šarić, Anđela; Habchi, Johnny; Chia, Sean; Meisl, Georg; Vendruscolo, Michele; Dobson, Christopher M; Knowles, Tuomas P J

    2018-04-20

    Understanding how normally soluble peptides and proteins aggregate to form amyloid fibrils is central to many areas of modern biomolecular science, ranging from the development of functional biomaterials to the design of rational therapeutic strategies against increasingly prevalent medical conditions such as Alzheimer's and Parkinson's diseases. As such, there is a great need to develop models to mechanistically describe how amyloid fibrils are formed from precursor peptides and proteins. Here we review and discuss how ideas and concepts from chemical reaction kinetics can help to achieve this objective. In particular, we show how a combination of theory, experiments, and computer simulations, based on chemical kinetics, provides a general formalism for uncovering, at the molecular level, the mechanistic steps that underlie the phenomenon of amyloid fibril formation.

  15. Chemical Kinetics for Bridging Molecular Mechanisms and Macroscopic Measurements of Amyloid Fibril Formation

    Science.gov (United States)

    Michaels, Thomas C. T.; Šarić, Anđela; Habchi, Johnny; Chia, Sean; Meisl, Georg; Vendruscolo, Michele; Dobson, Christopher M.; Knowles, Tuomas P. J.

    2018-04-01

    Understanding how normally soluble peptides and proteins aggregate to form amyloid fibrils is central to many areas of modern biomolecular science, ranging from the development of functional biomaterials to the design of rational therapeutic strategies against increasingly prevalent medical conditions such as Alzheimer's and Parkinson's diseases. As such, there is a great need to develop models to mechanistically describe how amyloid fibrils are formed from precursor peptides and proteins. Here we review and discuss how ideas and concepts from chemical reaction kinetics can help to achieve this objective. In particular, we show how a combination of theory, experiments, and computer simulations, based on chemical kinetics, provides a general formalism for uncovering, at the molecular level, the mechanistic steps that underlie the phenomenon of amyloid fibril formation.

  16. Molecular changes during chemical acidification of the buffalo and cow milks

    Directory of Open Access Journals (Sweden)

    F. Gaucheron

    2010-02-01

    Full Text Available Composition and physico-chemical properties of buffalo and cow milks were compared at their initial pH and during chemical acidification. As compare to cow milk, buffalo milk was richer in caseins and minerals such as Ca, Mg and Pi. Along with these differences, the capacity of buffalo milk to be acidified named buffering capacity was also higher than cow milk. The pH decrease induced aggregation of caseins at their isoelectric pH and solubilisations of Ca and Pi were significant for both milks. For both species, these molecular changes were qualitatively similar but quantitatively different. These differences suggested that the acidification process in dairy technology which is well established for cow milk can not be directly extrapolated to buffalo milk and some adaptations are necessary.

  17. NONLINEAR OPTICAL MOLECULAR CRYSTAL BASED ON 2,6-DIAMINOPYRIDINE: SYNTHESIS AND CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    I. M. Pavlovetc

    2014-05-01

    Full Text Available The paper deals with investigation of a new nonlinear optical material based on nonlinear optical chromophore (4-Nitrophenol and aminopyridine (2,6-Diaminopyridine. Calculation results are presented for molecular packing in the crystalline compound, based on the given components. According to these results the finite material must have a noncentrosymmetric lattice, which determines the presence of the second order nonlinear optical response. Investigations carried out in this work confirm these calculations. Results of experiments are given describing the co-crystallization of these components and the following re-crystallization of the obtained material. In order to get a monocrystal form, the optimal conditions for the synthesis of molecular crystals based on these components are determined. Sufficiently large homogeneous crystals are obtained, that gave the possibility to record their spectra in the visible and near infrared parts of the spectrum, to determine their nonlinear optical properties and the level of homogeneity. Their optical (optical transmission and optical laser damage threshold and nonlinear optical properties are presented. For observation and measurement of the nonlinear optical properties an installation was built which implements the comparative method for measurements of nonlinear optical properties. A potassium titanyl oxide phosphate crystal was used as a sample for comparison. Results are given for the conversion efficiency of the primary laser radiation in the second optical harmonic relative to the signal obtained on the potassium titanyl oxide phosphate crystal. Obtained results show that the molecular co-crystal based on 2,6-Diaminopyridine is a promising nonlinear optical material for generating the second optical harmonic on the Nd: YAG laser (532 nm.

  18. Nonequilibrium Chemical Effects in Single-Molecule SERS Revealed by Ab Initio Molecular Dynamics Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Sean A.; Apra, Edoardo; Govind, Niranjan; Hess, Wayne P.; El-Khoury, Patrick Z.

    2017-02-03

    Recent developments in nanophotonics have paved the way for achieving significant advances in the realm of single molecule chemical detection, imaging, and dynamics. In particular, surface-enhanced Raman scattering (SERS) is a powerful analytical technique that is now routinely used to identify the chemical identity of single molecules. Understanding how nanoscale physical and chemical processes affect single molecule SERS spectra and selection rules is a challenging task, and is still actively debated. Herein, we explore underappreciated chemical phenomena in ultrasensitive SERS. We observe a fluctuating excited electronic state manifold, governed by the conformational dynamics of a molecule (4,4’-dimercaptostilbene, DMS) interacting with a metallic cluster (Ag20). This affects our simulated single molecule SERS spectra; the time trajectories of a molecule interacting with its unique local environment dictates the relative intensities of the observable Raman-active vibrational states. Ab initio molecular dynamics of a model Ag20-DMS system are used to illustrate both concepts in light of recent experimental results.

  19. Development of a method for environmentally friendly chemical peptide synthesis in water using water-dispersible amino acid nanoparticles

    Directory of Open Access Journals (Sweden)

    Fukumori Yoshinobu

    2011-08-01

    Full Text Available Abstract Due to the vast importance of peptides in biological processes, there is an escalating need for synthetic peptides to be used in a wide variety of applications. However, the consumption of organic solvent is extremely large in chemical peptide syntheses because of the multiple condensation steps in organic solvents. That is, the current synthesis method is not environmentally friendly. From the viewpoint of green sustainable chemistry, we focused on developing an organic solvent-free synthetic method using water, an environmentally friendly solvent. Here we described in-water synthesis technology using water-dispersible protected amino acids.

  20. Synthesis of a nanoporous molecularly imprinted polymers for dibutyl Phthalate extracted from Trichoderma Harzianum

    Directory of Open Access Journals (Sweden)

    Maede Shahiri Tabarestani

    2016-07-01

    Full Text Available In this study, molecularly imprinted polymers were synthesized for dibutyl phthalate as a bioactive chemical compound with antifungal activity which produced by Trichoderma Harzianum (JX1738521. The molecularly imprinted polymers were synthesized via precipitation polymerization method from methacrylic acid, dibutyl phthalate and trimetylolpropantrimethacrylate as a functional monomer, template and cross-linker, respectively. After removal of the template by the eluent from the MIPs, the leached nanoparticles of the MIPs had a good binding capacity as equal 830 mg/g. The polymer particles have been evaluated by field emission scan electron microscopy and Brunauer–Emmett–Teller  techniques. The excellent specific surface area in the molecularly imprinted polymers as equal to 690.301 m2/g comparatively to non-imprinted polymers (ca. 89.894 m2/g, confirms that the nanoporous MIPs were synthesized, successfully. The results indicated that the nanoporous MIPs can be used in solid phase extraction. This is a novel method for separation of the bioactive compounds from fungi secondary metabolites in biological control.

  1. Conception and synthesis of the new cryptophane for the applications in xenon NMR molecular imaging

    International Nuclear Information System (INIS)

    Gao, Bo

    2016-01-01

    Among all the imaging techniques, magnetic resonance imaging (MRI) offers several advantages owing to its low invasiveness, its harmlessness and its spatial in-depth resolution but suffers from poor sensitivity. To address this issue, different strategies were proposed, including the utilization of hyper-polarizable species such as "1"2"9Xe. Xenon is an inert gas with a polarizable electronic cloud which leads to an extreme sensitivity to its chemical environment. Its capacity of being hyper-polarized makes it possible to obtain a significant gain of sensitivity. Nevertheless, xenon has no specificity to any biological target therefore it needs to be encapsulated and vectorized. Different molecular cages were proposed and we are particularly interested in cryptophane which is one of the best candidates for xenon encapsulation. In this context, the objective of this thesis is to design new cryptophanes which can be used as molecular platforms to construct novel "1"2"9Xe MRI biosensors usable for in vivo imaging. To meet this demand, these cryptophanes should be mono-functionalizable and enough soluble in water. In this thesis, the polyethylene glycol (PEG) group is used to improve the poor solubility of the hydrophobic molecular cage. And there is a systematic discussion of how to break the symmetry of cryptophanes and different strategies were attempted to synthesize mono-functionalized cryptophanes. As a result, several PEGylated mono-functionalized cryptophanes were obtained and their properties for encapsulating xenon were tested [fr

  2. Quantum chemical molecular dynamical investigation of alkyl nitrite photo-dissociated on copper surfaces

    International Nuclear Information System (INIS)

    Wang Xiaojing; Wang Wei; Han Peilin; Kubo, Momoji; Miyamoto, Akira

    2008-01-01

    An accelerated quantum chemical molecular dynamical code 'Colors-Excite' was used to investigate the photolysis of alkyl nitrites series, RONO (R=CH 3 and C(CH 3 ) 3 ) on copper surfaces. Our calculations showed that the photo-dissociated processes are associated with the alkyl substituents of RONO when adsorbed on copper surfaces. For R=CH 3 , a two-step photolysis reaction occurred, yielding diverse intermediate products including RO radical, NO, and HNO, consistent with those reported in gas phase. While for R=C(CH 3 ) 3 , only one-step photolysis reaction occurred and gave intermediate products of RO radical and NO. Consequently, pure RO species were achieved to adsorb on metal surfaces by removing the NO species in photolysis reaction. The detailed photo-dissociated behaviors of RONO on copper surfaces with different alkyl substituents which are uncovered by the present simulation can be extended to explain the diverse dissociative mechanism experimentally observed. The quantum chemical molecular dynamical code 'Colors-Excite' is proved to be highly applicable to the photo-dissociations on metal surfaces

  3. Actinide tris(hydrocarbyls). Synthesis, properties, structure, and molecular dynamics of thorium and uranium pentamethylcyclopentadienyl tris(eta/sup n/-benzyls)

    International Nuclear Information System (INIS)

    Mintz, E.A.; Moloy, K.G.; Marks, T.J.; Day, V.W.

    1982-01-01

    This report focuses on the synthesis, unusual molecular structure(s), and other interesting properties of ligands within a metal coordination sphere (cf. M(eta 5 -C 5 H 5 ) 3 R vs. M[eta 5 -(CH 3 ) 5 ] 2 R 2 chemistry, where M=Th or U). This report represents a continuing effort to ''tune'' the actinide ligation environment with respect to such factors as the chemical characteristics of actinide-to-carbon sigma bonds. These bonds are a sensitive function of the number and nature of the other ligands within the metal coordination sphere. Structural analysis is reported that examines the nature and arrangement of the bonds in Th[eta 5 -(CH 3 ) 5 C 5 ](CH 2 C 6 H 5 ) 3 and U[eta 5 -(CH 3 ) 5 C 5 ](CH 2 C 6 H 5 ) 3 complexes

  4. The Synthesis of Calcium Salt from Brine Water by Partial Evaporation and Chemical Precipitation

    Science.gov (United States)

    Lalasari, L. H.; Widowati, M. K.; Natasha, N. C.; Sulistiyono, E.; Prasetyo, A. B.

    2017-02-01

    chemical precipitation using (NH4)2CO3 reagent are recommended in the synthesis of calcium salts from brine water because are simple, flexible and economical.

  5. Ultrasound-assisted acid hydrolysis of cellulose to chemical building blocks: Application to furfural synthesis.

    Science.gov (United States)

    Santos, Daniel; Silva, Ubiratan F; Duarte, Fabio A; Bizzi, Cezar A; Flores, Erico M M; Mello, Paola A

    2018-01-01

    In this work, the use of ultrasound energy for the production of furanic platforms from cellulose was investigated and the synthesis of furfural was demonstrated. Several systems were evaluated, as ultrasound bath, cup horn and probe, in order to investigate microcrystalline cellulose conversion using simply a diluted acid solution and ultrasound. Several acid mixtures were evaluated for hydrolysis, as diluted solutions of HNO 3 , H 2 SO 4 , HCl and H 2 C 2 O 4 . The influence of the following parameters in the ultrasound-assisted acid hydrolysis (UAAH) were studied: sonication temperature (30 to 70°C) and ultrasound amplitude (30 to 70% for a cup horn system) for 4 to 8molL -1 HNO 3 solutions. For each evaluated condition, the products were identified by ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-ToF-MS), which provide accurate information regarding the products obtained from biomass conversion. The furfural structure was confirmed by nuclear magnetic resonance ( 1 H and 13 C NMR) spectroscopy. In addition, cellulosic residues from hydrolysis reaction were characterized using scanning electron microscopy (SEM), which contributed for a better understanding of physical-chemical effects caused by ultrasound. After process optimization, a 4molL -1 HNO 3 solution, sonicated for 60min at 30°C in a cup horn system at 50% of amplitude, lead to 78% of conversion to furfural. This mild temperature condition combined to the use of a diluted acid solution represents an important contribution for the selective production of chemical building blocks using ultrasound energy. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Identification of critical chemical features for Aurora kinase-B inhibitors using Hip-Hop, virtual screening and molecular docking

    Science.gov (United States)

    Sakkiah, Sugunadevi; Thangapandian, Sundarapandian; John, Shalini; Lee, Keun Woo

    2011-01-01

    This study was performed to find the selective chemical features for Aurora kinase-B inhibitors using the potent methods like Hip-Hop, virtual screening, homology modeling, molecular dynamics and docking. The best hypothesis, Hypo1 was validated toward a wide range of test set containing the selective inhibitors of Aurora kinase-B. Homology modeling and molecular dynamics studies were carried out to perform the molecular docking studies. The best hypothesis Hypo1 was used as a 3D query to screen the chemical databases. The screened molecules from the databases were sorted based on ADME and drug like properties. The selective hit compounds were docked and the hydrogen bond interactions with the critical amino acids present in Aurora kinase-B were compared with the chemical features present in the Hypo1. Finally, we suggest that the chemical features present in the Hypo1 are vital for a molecule to inhibit the Aurora kinase-B activity.

  7. Molecular corridors and parameterizations of volatility in the chemical evolution of organic aerosols

    Directory of Open Access Journals (Sweden)

    Y. Li

    2016-03-01

    Full Text Available The formation and aging of organic aerosols (OA proceed through multiple steps of chemical reaction and mass transport in the gas and particle phases, which is challenging for the interpretation of field measurements and laboratory experiments as well as accurate representation of OA evolution in atmospheric aerosol models. Based on data from over 30 000 compounds, we show that organic compounds with a wide variety of functional groups fall into molecular corridors, characterized by a tight inverse correlation between molar mass and volatility. We developed parameterizations to predict the saturation mass concentration of organic compounds containing oxygen, nitrogen, and sulfur from the elemental composition that can be measured by soft-ionization high-resolution mass spectrometry. Field measurement data from new particle formation events, biomass burning, cloud/fog processing, and indoor environments were mapped into molecular corridors to characterize the chemical nature of the observed OA components. We found that less-oxidized indoor OA are constrained to a corridor of low molar mass and high volatility, whereas highly oxygenated compounds in atmospheric water extend to high molar mass and low volatility. Among the nitrogen- and sulfur-containing compounds identified in atmospheric aerosols, amines tend to exhibit low molar mass and high volatility, whereas organonitrates and organosulfates follow high O : C corridors extending to high molar mass and low volatility. We suggest that the consideration of molar mass and molecular corridors can help to constrain volatility and particle-phase state in the modeling of OA particularly for nitrogen- and sulfur-containing compounds.

  8. Large influence of the synthesis conditions on the physico-chemical properties of nanostructured Fe3O4

    International Nuclear Information System (INIS)

    Franger, S.; Berthet, P.; Dragos, O.; Baddour-Hadjean, R.; Bonville, P.; Berthon, J.

    2007-01-01

    Magnetite synthesized via three different synthesis routes (coprecipitation process in aqueous media, electrochemical synthesis in presence of complexing agents and solid state reaction at high temperature) has been characterized by X-Ray diffraction, scanning electron microscopy, thermal analysis (TGA), FT-IR and Moessbauer spectroscopies. Although each procedure gave homogeneous magnetite powders, many differences could be seen in the physico-chemical properties of the samples mostly depending on the synthesis conditions. For instance, at least two factors seem to have a huge impact onto the Fe 3 O 4 behaviour: the presence of hydration water molecules and the particle size of the powders since a superparamagnetic behaviour was observed with the thinnest particles, at room temperature, on the Moessbauer spectra via the appearance of line broadening and a pronounced central doublet

  9. Synthesis and application of molecularly imprinted polymers for the selective extraction of organophosphorus pesticides from vegetable oils.

    Science.gov (United States)

    Boulanouar, Sara; Combès, Audrey; Mezzache, Sakina; Pichon, Valérie

    2017-09-01

    The increasing use of pesticides in agriculture causes environmental issues and possible serious health risks to humans and animals. Their determination at trace concentrations in vegetable oils constitutes a significant analytical challenge. Therefore, their analysis often requires both an extraction and a purification step prior to separation with liquid chromatography (LC) and mass spectrometry (MS) detection. This work aimed at developing sorbents that are able to selectively extract from vegetable oil samples several organophosphorus (OPs) pesticides presenting a wide range of physico-chemical properties. Therefore, different conditions were screened to prepare molecularly imprinted polymers (MIPs) by a non-covalent approach. The selectivity of the resulting polymers was evaluated by studying the OPs retention in pure media on both MIPs and non-imprinted polymers (NIP) used as control. The most promising MIP sorbent was obtained using monocrotophos (MCP) as the template, methacrylic acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker with a molar ratio of 1/4/20 respectively. The repeatability of the extraction procedure and of the synthesis procedure was demonstrated in pure media. The capacity of this MIP was 1mg/g for malathion. This MIP was also able to selectively extract three OPs from almond oil by applying the optimized SPE procedure. Recoveries were between 73 and 99% with SD values between 4 and 6% in this oil sample. The calculated LOQs (between 0.3 and 2μg/kg) in almond seeds with a SD between 0.1 and 0.4μg/kg were lower than the Maximum Residue Levels (MRLs) established for the corresponding compounds in almond seed. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Synthesis of Mesoporous Carbons from Date Pits for the Adsorption of Large Molecular Weight Micropollutants in Wastewater

    KAUST Repository

    Al Jeffrey, Ahmed

    2013-07-01

    Efficient reuse of waste water requires removal of micro-pollutants from waste water streams by affordable and sustainable methods. Activated carbon is considered a powerful adsorbent due to its high surface area and low cost of treatment, compared to other expensive methods such as membrane filtration. Producing activated carbon with larger mesoporosity (>2nm) is of particular interest in industry in the removal of larger molecular sized pollutants. This study reports the synthesis of mesoporous activated carbons from a nonsoluble biomass precursor (date-pits) along with chemical activation using ZnCl2. Thus, produced activated carbon showed high surface area and large mesopore volume up to 1571 m2/g and 2.00 cm3/g respectively. In addition, the pore size of the product was as high as 9.30 nm. As a method of verification, HRTEM (Highresolution transmission electron microscopy) was used to directly authenticate the pore size of the synthesized activated carbons. Tannic acid and atrazine were used as model waste water pollutants and the adsorption capability of the produced activated carbon for these pollutants were evaluated and compared to a commercial mesoporous carbon: G60 from Norit. The results showed that the sorption capacity of produced activated carbon for tannic acid was 2 times that of G60 while the sorption capacity of produced activated carbon for atrazine was lower than that of G60. The activated carbon was also evaluated for adsorption of real secondary effluent municipal wastewater and the results suggest that the produced activated carbon was able to sorb a greater amount of biopolymers than G60. These results demonstrate that the thus-produced activated carbon may be a promising sorbent for waste water treatment.

  11. Formation of a Molecular Wire Using the Chemically Adsorbed Monomolecular Layer Having Pyrrolyl Groups

    Directory of Open Access Journals (Sweden)

    Kazufumi Ogawa

    2011-01-01

    Full Text Available A molecular wire containing polypyrrolyl conjugate bonds has been prepared by a chemical adsorption technique using 1,1,1-trichloro-12-pyrrolyl-1-siladodecane (PNN and an electrooxidative polymerization technique, and the conductivity of the molecular wire without any dopant has been measured by using AFM/STM at room temperature. When sample dimension measured was about 0.3 nm (thickness of the conductive portion in the PNN monomolecular layer ×100 μm (the average width of an electric path ×2 mm (the distance between Pt positive electrode and the AFM tip covered with Au, the conductivity of the polymerized PNN molecular wire at room temperature was larger than 1.6 × 105 S/cm both in an atmosphere and in a vacuum chamber of 10−5 Torr. The activation energy obtained by Arrhenius' plots was almost zero in the temperature range between 320 and 450 K.

  12. Mass spectral chemical fingerprints reveal the molecular dependence of exhaust particulate matters on engine speeds.

    Science.gov (United States)

    Li, Yi; Zhang, Hua; Zhao, Zongshan; Tian, Yong; Liu, Kun; Jie, Feifan; Zhu, Liang; Chen, Huanwen

    2018-05-01

    Particulate matters (PMs) emitted by automobile exhaust contribute to a significant fraction of the global PMs. Extractive atmospheric pressure chemical ionization mass spectrometry (EAPCI-MS) was developed to explore the molecular dependence of PMs collected from exhaust gases produced at different vehicle engine speeds. The mass spectral fingerprints of the organic compounds embedded in differentially sized PMs (e.g., 0.22-0.45, 0.45-1.00, 1.00-2.00, 2.00-3.00, 3.00-5.00, and 5.00-10.00μm) generated at different engine speeds (e.g., 1000, 1500, 2000, 2500, and 3000r/min) were chemically profiled in the mass range of mass to charge ratio (m/z) 50-800. Organic compounds, including alcohols, aldehydes, and esters, were detected in all the PMs tested, with varied concentration levels for each individual PM sample. At relatively low engine speeds (≤1500r/min), the total amount of organic species embedded in PMs of 0.22-1.00μm was greater than in PMs of other sizes, while more organic species were found in PMs of 5.00-10.00μm at high engine speeds (≥3000r/min), indicating that the organic compounds distributed in different sizes of PMs strongly correlated with the engine speed. The experimental data showed that the EAPCI-MS technique enables molecular characterization of PMs in exhaust, revealing the chemical dependence of PMs on the engine speeds (i.e., the combustion conditions) of automobiles. Copyright © 2017. Published by Elsevier B.V.

  13. Sensing signatures mediated by chemical structure of molecular solids in laser-induced plasmas.

    Science.gov (United States)

    Serrano, Jorge; Moros, Javier; Laserna, J Javier

    2015-03-03

    Laser ablation of organic compounds has been investigated for almost 30 years now, either in the framework of pulse laser deposition for the assembling of new materials or in the context of chemical sensing. Various monitoring techniques such as atomic and molecular fluorescence, time-of-flight mass spectrometry, and optical emission spectroscopy have been used for plasma diagnostics in an attempt to understand the spectral signature and potential origin of gas-phase ions and fragments from organic plasmas. Photochemical and photophysical processes occurring within these systems are generally much more complex than those suggested by observation of optical emission features. Together with laser ablation parameters, the structural and chemical-physical properties of molecules seem to be closely tied to the observed phenomena. The present manuscript, for the first time, discusses the role of molecular structure in the optical emission of organic plasmas. Factors altering the electronic distribution within the organic molecule have been found to have a direct impact on its ensuing optical emissions. The electron structure of an organic molecule, resulting from the presence, nature, and position of its atoms, governs the breakage of the molecule and, as a result, determines the extent of atomization and fragmentation that has proved to directly impact the emissions of CN radicals and C2 dimers. Particular properties of the molecule respond more positively depending on the laser irradiation wavelength, thereby redirecting the ablation process through photochemical or photothermal decomposition pathways. It is of paramount significance for chemical identification purposes how, despite the large energy stored and dissipated by the plasma and the considerable number of transient species formed, the emissions observed never lose sight of the original molecule.

  14. Nanostructured Thin Film Synthesis by Aerosol Chemical Vapor Deposition for Energy Storage Applications

    Science.gov (United States)

    Chadha, Tandeep S.

    Renewable energy sources offer a viable solution to the growing energy demand while mitigating concerns for greenhouse gas emissions and climate change. This has led to a tremendous momentum towards solar and wind-based energy harvesting technologies driving efficiencies higher and costs lower. However, the intermittent nature of these energy sources necessitates energy storage technologies, which remain the Achilles heel in meeting the renewable energy goals. This dissertation focusses on two approaches for addressing the needs of energy storage: first, targeting direct solar to fuel conversion via photoelectrochemical water-splitting and second, improving the performance of current rechargeable batteries by developing new electrode architectures and synthesis processes. The aerosol chemical vapor deposition (ACVD) process has emerged as a promising single-step approach for nanostructured thin film synthesis directly on substrates. The relationship between the morphology and the operating parameters in the process is complex. In this work, a simulation based approach has been developed to understand the relationship and acquire the ability of predicting the morphology. These controlled nanostructured morphologies of TiO2 , compounded with gold nanoparticles of various shapes, are used for solar water-splitting applications. Tuning of light absorption in the visible-light range along with reduced electron-hole recombination in the composite structures has been demonstrated. The ACVD process is further extended to a novel single-step synthesis of nanostructured TiO2 electrodes directly on the current collector for applications as anodes in lithium-ion batteries, mainly for electric vehicles and hybrid electric vehicles. The effect of morphology of the nanostructures has been investigated via experimental studies and electrochemical transport modelling. Results demonstrate the exceptional performance of the single crystal one-dimensional nanostructures over granular

  15. Hot-wire chemical vapor synthesis for a variety of nano-materials with novel applications

    International Nuclear Information System (INIS)

    Dillon, A.C.; Mahan, A.H.; Deshpande, R.; Alleman, J.L.; Blackburn, J.L.; Parillia, P.A.; Heben, M.J.; Engtrakul, C.; Gilbert, K.E.H.; Jones, K.M.; To, R.; Lee, S-H.; Lehman, J.H.

    2006-01-01

    Hot-wire chemical vapor deposition (HWCVD) has been demonstrated as a simple economically scalable technique for the synthesis of a variety of nano-materials in an environmentally friendly manner. For example we have employed HWCVD for the continuous production of both carbon single- and multi-wall nanotubes (SWNTs and MWNTs). Unanticipated hydrogen storage on HWCVD-generated MWNTs has led insight into the adsorption mechanism of hydrogen on metal/carbon composites at near ambient temperatures that could be useful for developing a vehicular hydrogen storage system. Recent efforts have been focused on growing MWNT arrays on thin nickel films with a simple HWCVD process. New data suggests that these MWNT arrays could replace the gold black coatings currently used in pyroelectric detectors to accurately measure laser power. Finally, we have very recently employed HWCVD for the production of crystalline molybdenum and tungsten oxide nanotubes and nanorods. These metal oxide nanorods and nanotubes could have applications in catalysis, batteries and electrochromic windows or as gas sensors. A summary of the techniques for growing these novel materials and their various potential applications is provided

  16. The nature of outsourced preclinical research--the example of chemical synthesis.

    Science.gov (United States)

    Festel, Gunter W

    2013-09-01

    The possibility to buy standardized external services or even new and innovative methods within drug discovery has increased dramatically during the last decades. Service providers are able to provide timely and efficient solutions to any given problem within preclinical research. The outsourcing behavior depends on the specific company type. Generally, the outsourcing level of emerging pharmaceutical and biotechnology companies is much higher than established companies due to low or missing internal resources. Whereas the "make-or-buy" decisions of large and fully integrated pharmaceutical companies are mainly competency driven, those of mid-size and small pharmaceutical, as well as biotech companies show a specific combination of cost/capacity and competency. The three different cooperation models "price competition", "project selection," and "strategic partnership" were identified. For all types of companies, the cooperation model of "strategic partnership" offers access to high-level expertise while reducing fixed costs and complexity. This was shown using chemical synthesis as an example but is also true for other areas of preclinical research.

  17. Synthesis of Copper Nanoparticles in Ethylene Glycol by Chemical Reduction with Vanadium (+2 Salts

    Directory of Open Access Journals (Sweden)

    Andrea Pietro Reverberi

    2016-09-01

    Full Text Available Copper nanoparticles have been synthesized in ethylene glycol (EG using copper sulphate as a precursor and vanadium sulfate as an atypical reductant being active at room temperature. We have described a technique for a relatively simple preparation of such a reagent, which has been electrolytically produced without using standard procedures requiring an inert atmosphere and a mercury cathode. Several stabilizing agents have been tested and cationic capping agents have been discarded owing to the formation of complex compounds with copper ions leading to insoluble phases contaminating the metallic nanoparticles. The elemental copper nanoparticles, stabilized with polyvinylpyrrolidone (PVP and sodium dodecyl sulphate (SDS, have been characterized for composition by energy dispersive X-ray spectroscopy (EDS, and for size by dynamic light scattering (DLS, and transmission electron microscopy (TEM, giving a size distribution in the range of 40–50 nm for both stabilizing agents. From a methodological point of view, the process described here may represent an alternative to other wet-chemical techniques for metal nanoparticle synthesis in non-aqueous media based on conventional organic or inorganic reductants.

  18. Synthesis of Nickel and Nickel Hydroxide Nanopowders by Simplified Chemical Reduction

    Directory of Open Access Journals (Sweden)

    Jeerapan Tientong

    2014-01-01

    Full Text Available Nickel nanopowders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at pH ~12.5. Sonication of the solutions created a temperature of 54–65°C to activate the reduction reaction of nickel nanoparticles. The solution pH affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (pH~10 of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.

  19. Synthesis of mono and multidomain YIG particles by chemical coprecipitation or ceramic procedure

    International Nuclear Information System (INIS)

    Fernandez-Garcia, L.; Suarez, M.; Menendez, J.L.

    2010-01-01

    Yttrium iron garnet powders have been synthesized by chemical coprecipitation using two different precursors, nitrates and chlorides, and by an oxides mixture route. It is shown that depending on the precursors and synthesis conditions used pure yttrium iron garnet powders can be obtained with a mono or multidomain magnetic behaviour. The yttrium iron garnet crystalline structure, as studied by Raman spectroscopy, was already formed after calcination at temperatures as low as 800 o C when the nitrate precursors were used. However, calcination temperatures of up to 1100 o C were required to obtain yttrium iron garnet powders when the precursors were chlorides or when the oxides mixture route was chosen. The saturation magnetization of the powders correlates well with the structural characterization: when nitrate precursors were used, the saturation magnetization was already close to the bulk value, 26.8 emu/cm 3 , after calcination at 800 o C. However, the saturation magnetization of the powders obtained by the chlorides and oxides mixture routes was close to zero up to calcination temperatures of 1100 o C. Finally, both the chlorides and the oxides mixture routes yield multidomain micron sized yttrium iron garnet powders, whereas the nitrates route led to monodomain submicron sized powders.

  20. Physico-Chemical and In-vitro Microbial Studies of Newly Synthesis Organometallic Complexes

    Directory of Open Access Journals (Sweden)

    Isam Hussain Al-Karkhi

    2014-05-01

    Full Text Available Drugs normally synthesized to use as medication to treat diseases like cancer and microbial infections, these synthesized drugs were interested more than naturally-derived drugs which have been shows low activity or not as efficient against diseases. A new ligand 3-methylbenzyl (2Z-2-[1-(pyridin-4-ylethylidene]hydrazine carbodithioate (PE3MBC and its Cd(II, Cu(II, Co(II and Zn(II metal complexes. The new ligand and metal complexes were characterized via various physico-chemical and spectroscopic techniques. Cd(II complex show more activity against microbes and against cancer cell line MCF-7, while other complexes does not shows activity like cadmium complex, all the complexes does not shows any activity against MDAMB-231 cell line. The fatal of the cancer and the microbes cell was due to inhibition of DNA synthesis which was probably due to chelating with metals complexes, or could be referred to lipophilicity, presence of hydrophobic moiety in the complex molecule, also could be due to steric effects and electronic effects.

  1. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Djenadic, Ruzica; Winterer, Markus, E-mail: markus.winterer@uni-due.de [Universität Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and CENIDE (Germany)

    2017-02-15

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  2. Electrical properties of aluminum-doped zinc oxide (AZO) nanoparticles synthesized by chemical vapor synthesis

    International Nuclear Information System (INIS)

    Hartner, Sonja; Schulz, Christof; Wiggers, Hartmut; Ali, Moazzam; Winterer, Markus

    2009-01-01

    Aluminum-doped zinc oxide nanoparticles have been prepared by chemical vapor synthesis, which facilitates the incorporation of a higher percentage of dopant atoms, far above the thermodynamic solubility limit of aluminum. The electrical properties of aluminum-doped and undoped zinc oxide nanoparticles were investigated by impedance spectroscopy. The impedance is measured under hydrogen and synthetic air between 323 and 673 K. The measurements under hydrogen as well as under synthetic air show transport properties depending on temperature and doping level. Under hydrogen atmosphere, a decreasing conductivity with increasing dopant content is observed, which can be explained by enhanced scattering processes due to an increasing disorder in the nanocrystalline material. The temperature coefficient for the doped samples switches from positive temperature coefficient behavior to negative temperature coefficient behavior with increasing dopant concentration. In the presence of synthetic air, the conductivity firstly increases with increasing dopant content by six orders of magnitude. The origin of the increasing conductivity is the generation of free charge carriers upon dopant incorporation. It reaches its maximum at a concentration of 7.7% of aluminum, and drops for higher doping levels. In all cases, the conductivity under hydrogen is higher than under synthetic air and can be changed reversibly by changing the atmosphere.

  3. Electrical properties of aluminum-doped zinc oxide (AZO) nanoparticles synthesized by chemical vapor synthesis.

    Science.gov (United States)

    Hartner, Sonja; Ali, Moazzam; Schulz, Christof; Winterer, Markus; Wiggers, Hartmut

    2009-11-04

    Aluminum-doped zinc oxide nanoparticles have been prepared by chemical vapor synthesis, which facilitates the incorporation of a higher percentage of dopant atoms, far above the thermodynamic solubility limit of aluminum. The electrical properties of aluminum-doped and undoped zinc oxide nanoparticles were investigated by impedance spectroscopy. The impedance is measured under hydrogen and synthetic air between 323 and 673 K. The measurements under hydrogen as well as under synthetic air show transport properties depending on temperature and doping level. Under hydrogen atmosphere, a decreasing conductivity with increasing dopant content is observed, which can be explained by enhanced scattering processes due to an increasing disorder in the nanocrystalline material. The temperature coefficient for the doped samples switches from positive temperature coefficient behavior to negative temperature coefficient behavior with increasing dopant concentration. In the presence of synthetic air, the conductivity firstly increases with increasing dopant content by six orders of magnitude. The origin of the increasing conductivity is the generation of free charge carriers upon dopant incorporation. It reaches its maximum at a concentration of 7.7% of aluminum, and drops for higher doping levels. In all cases, the conductivity under hydrogen is higher than under synthetic air and can be changed reversibly by changing the atmosphere.

  4. Chemical synthesis, 3D structure, and ASIC binding site of the toxin mambalgin-2.

    Science.gov (United States)

    Schroeder, Christina I; Rash, Lachlan D; Vila-Farrés, Xavier; Rosengren, K Johan; Mobli, Mehdi; King, Glenn F; Alewood, Paul F; Craik, David J; Durek, Thomas

    2014-01-20

    Mambalgins are a novel class of snake venom components that exert potent analgesic effects mediated through the inhibition of acid-sensing ion channels (ASICs). The 57-residue polypeptide mambalgin-2 (Ma-2) was synthesized by using a combination of solid-phase peptide synthesis and native chemical ligation. The structure of the synthetic toxin, determined using homonuclear NMR, revealed an unusual three-finger toxin fold reminiscent of functionally unrelated snake toxins. Electrophysiological analysis of Ma-2 on wild-type and mutant ASIC1a receptors allowed us to identify α-helix 5, which borders on the functionally critical acidic pocket of the channel, as a major part of the Ma-2 binding site. This region is also crucial for the interaction of ASIC1a with the spider toxin PcTx1, thus suggesting that the binding sites for these toxins substantially overlap. This work lays the foundation for structure-activity relationship (SAR) studies and further development of this promising analgesic peptide. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Layer-selective synthesis of bilayer graphene via chemical vapor deposition

    Science.gov (United States)

    Yang, Ning; Choi, Kyoungjun; Robertson, John; Park, Hyung Gyu

    2017-09-01

    A controlled synthesis of high-quality AB-stacked bilayer graphene by chemical vapor deposition demands a detailed understanding of the mechanism and kinetics. By decoupling the growth of the two layers via a growth-and-regrowth scheme, we report the kinetics and termination mechanisms of the bilayer graphene growth on copper. We observe, for the first time, that the secondary layer growth follows Gompertzian kinetics. Our observations affirm the postulate of a time-variant transition from a mass-transport-limited to a reaction-limited regimes and identify the mechanistic disparity between the monolayer growth and the secondary-layer expansion underneath the monolayer cover. It is the continuous carbon supply that drives the expansion of the graphene secondary layer, rather than the initially captured carbon amount, suggesting an essential role of the surface diffusion of reactant adsorbates in the interspace between the top graphene layer and the underneath copper surface. We anticipate that the layer selectivity of the growth relies on the entrance energetics of the adsorbed reactants to the graphene-copper interspace across the primary-layer edge, which could be engineered by tailoring the edge termination state. The temperature-reliant saturation area of the secondary-layer expansion is understood as a result of competitive attachment of carbon and hydrogen adatoms to the secondary-layer graphene edge.

  6. Organocatalysts for enantioselective synthesis of fine chemicals: definitions, trends and developments

    Directory of Open Access Journals (Sweden)

    Chiara Palumbo

    2015-02-01

    Full Text Available Organocatalysis, that is the use of small organic molecules to catalyze organic transformations, has been included among the most successful concepts in asymmetric catalysis, and it has been used for the enantioselective construction of C–C, C–N, C–O, C–S, C–P and C–halide bonds. Since the seminal works in early 2000, the scientific community has been paying an ever-growing attention to the use of organocatalysts for the synthesis, with high yields and remarkable stereoselectivities, of optically active fine chemicals of interest for the pharmaceutical industry. A brief overview is here presented about the two main classes of substrate activation by the catalyst: covalent organocatalysis and non-covalent organocatalysis, with a more stringent focus on some recent outcomes in the field of the latter and of hydrogen bond-based catalysis. Finally, some successful examples of heterogenization of organocatalysts are also discussed, in the view of a potential industrial exploitation.

  7. Synthesis and characterization of hydroxyapatite nanoparticles by chemical precipitation method for potential application in water treatment

    Science.gov (United States)

    Joshi, Parth; Patel, Chirag; Vyas, Meet

    2018-05-01

    Hydroxyapatite (HA) is a unique material having high adsorption capacity of heavy metals, high ion exchange capacity, high biological compatibility, low water solubility, high stability under reducing and oxidizing conditions, availability and low cost. As the starting reagents, analytical grade Ca(NO3)2.4H2O, (NH4)2HPO4 and NaOH were used. In order to study the factors that have an important influence on the chemical precipitation process a experimental platform has been designed for hydroxyapatite synthesis. The addition of Phosphorus pentaoxide to Calcium hydroxide was carried out slowly with simultaneous stirring. After addition, solution was aged for maturation. The precipitate was dried at 80°C overnight and further heat treated at 600°C for 2 hours. The dried and calcined particles were characterized by Fourier transform infra-red spectroscopy and Thermo gravimetric analysis. The particle size and morphology were studied using transmission electron microscopy. TEM examination of the treated powders displayed particles of polygon morphology with dimensions 30-70 nm in length. The FT-IR spectra for sample confirmed the formation of hydroxyapatite. Purity of the prepared Hydroxyapatite has been confirmed by XRD analysis.

  8. Functionalized polypyrrole film: synthesis, characterization, and potential applications in chemical and biological sensors.

    Science.gov (United States)

    Dong, Hua; Cao, Xiaodong; Li, Chang Ming

    2009-07-01

    In this paper, we report the synthesis of a carboxyl-functionalized polypyrrole derivative, a poly(pyrrole-N-propanoic acid) (PPPA) film, by electrochemical polymerization, and the investigation of its basic properties via traditional characterization techniques such as confocal-Raman, FTIR, SEM, AFM, UV-vis, fluorescence microscopy, and contact-angle measurements. The experimental data show that the as-prepared PPPA film exhibits a hydrophilic nanoporous structure, abundant -COOH functional groups in the polymer backbone, and high fluorescent emission under laser excitation. On the basis of these unique properties, further experiments were conducted to demonstrate three potential applications of the PPPA film in chemical and biological sensors: a permeable and permselective membrane, a membrane with specific recognition sites for biomolecule immobilization, and a fluorescent conjugated polymer for amplification of fluorescence quenching. Specifically, the permeability and permselectivity of ion species through the PPPA film are detected by means of rotating-disk-electrode voltammetry; the specific recognition sites on the film surface are confirmed with protein immobilization, and the amplification of fluorescence quenching is measured by the addition of a quenching agent with fluorescence microscopy. The results are in good agreement with our expectations.

  9. One-step synthesis of chlorinated graphene by plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Liwei; Zhang, Hui; Zhang, Pingping; Sun, Xuhui, E-mail: xhsun@suda.edu.cn

    2015-08-30

    Highlights: • We developed a simple approach to synthesize the single layer chlorinated graphene. • CuCl{sub 2} on Cu surface is used as Cl source under the plasma treatment. • The formation of covalent C−Cl bond has been investigated by Raman and XPS. • Raman results indicate the p-type doping effect of chlorination. - Abstract: We developed an approach to synthesize the chlorinated single layer graphene (Cl-G) by one-step plasma enhanced chemical vapor deposition. Copper foil was simply treated with hydrochloric acid and then CuCl{sub 2} formed on the surface was used as Cl source under the assistance of plasma treatment. Compared with other two-step methods by post plasma/photochemical treatment of CVD-grown single layer graphene (SLG), one-step Cl-G synthesis approach is quite straightforward and effective. X-ray photoelectron spectroscopy (XPS) revealed that ∼2.45 atom% Cl remained in SLG. Compared with the pristine SLG, the obvious blue shifts of G band and 2D band along with the appearance of D’ band and D + G band in the Raman spectra indicate p-type doping of Cl-G.

  10. Sequential structural and optical evolution of MoS2 by chemical synthesis and exfoliation

    Science.gov (United States)

    Kim, Ju Hwan; Kim, Jungkil; Oh, Si Duck; Kim, Sung; Choi, Suk-Ho

    2015-06-01

    Various types of MoS2 structures are successfully obtained by using economical and facile sequential synthesis and exfoliation methods. Spherically-shaped lumps of multilayer (ML) MoS2 are prepared by using a conventional hydrothermal method and were subsequently 1st-exfoliated in hydrazine while being kept in autoclave to be unrolled and separated into five-to-six-layer MoS2 pieces of several-hundred nm in size. The MoS2 MLs are 2nd-exfoliated in sodium naphthalenide under an Ar ambient to finally produce bilayer MoS2 crystals of ~100 nm. The sequential exfoliation processes downsize MoS2 laterally and reduce its number of layers. The three types of MoS2 allotropes exhibit particular optical properties corresponding to their structural differences. These results suggest that two-dimensional MoS2 crystals can be prepared by employing only chemical techniques without starting from high-pressure-synthesized bulk MoS2 crystals.

  11. Direct chemical synthesis of MnO2 nanowhiskers on MXene surfaces for supercapacitor applications

    KAUST Repository

    Baby, Rakhi Raghavan

    2016-07-05

    Transition metal carbides (MXenes) are an emerging class of two dimensional (2D) materials with promising electrochemical energy storage performance. Herein, for the first time, by direct chemical synthesis, nanocrystalline ε-MnO2 whiskers were formed on MXene nanosheet surfaces (ε-MnO2/Ti2CTx and ε-MnO2/Ti3C2Tx) to make nanocomposite electrodes for aqueous pseudocapacitors. The ε-MnO2 nanowhiskers increase the surface area of the composite electrode and enhance the specific capacitance by nearly three orders of magnitude compared to pure MXene based symmetric supercapacitors. Combined with enhanced pseudocapacitance, the fabricated ε-MnO2/MXene supercapacitors exhibited excellent cycling stability with ~88% of the initial specific capacitance retained after 10000 cycles which is much higher than pure ε-MnO2 based supercapacitors (~74%). The proposed electrode structure capitalizes on the high specific capacitance of MnO2 and the ability of MXenes to improve conductivity and cycling stability.

  12. A molecular theory of chemically modified electrodes with self-assembled redox polyelectrolye thin films: Reversible cyclic voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Tagliazucchi, Mario; Calvo, Ernesto J. [INQUIMAE, DQIAyQF Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Szleifer, Igal [Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2008-10-01

    A molecular theory of chemically modified electrodes is applied to study redox polyelectroyte modified electrodes. The molecular approach explicitly includes the size, shape, charge distribution, and conformations of all of the molecular species in the system as well as the chemical equilibria (redox and acid-base) and intermolecular interactions. An osmium pyridine-bipyridine complex covalently bound to poly(allyl-amine) backbone (PAH-Os) adsorbed onto mercapto-propane sulfonate (MPS) thiolated gold electrode is described. The potential and electrolyte composition dependent redox and nonredox capacitance can be calculated with the molecular theory in very good agreement with voltammetric experiments under reversible conditions without the use of freely adjustable parameter. Unlike existing phenomenological models the theory links the electrochemical behavior with the structure of the polymer layer. The theory predicts a highly inhomogeneous distribution of acid-base and redox states that strongly couples with the spatial arrangement of the molecular species in the nanometric redox film. (author)

  13. Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

    Science.gov (United States)

    Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

    2015-12-01

    The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

  14. Synthesis, vibrational and quantum chemical investigations of hydrogen bonded complex betaine dihydrogen selenite

    Science.gov (United States)

    Arjunan, V.; Marchewka, Mariusz K.; Kalaivani, M.

    2012-10-01

    The molecular complex of betaine with selenious acid namely, betaine dihydrogen selenite (C5H13NO5Se, BDHSe) was synthesised by the reaction of betaine and SeO2 in a 1:1:1 solution of isopropanol, methanol and water. Crystals were grown from this solution by cooling to 253 K for few days. The complex was formed without accompanying proton transfer from selenious acid molecule to betaine. The complete vibrational assignments and analysis of BDHSe have been performed by FTIR, FT-Raman and far-infrared spectral studies. More support on the experimental findings was added from the quantum chemical studies performed with DFT (B3LYP) method using 6-311++G∗∗, 6-31G∗∗, cc-pVDZ and 3-21G basis sets. The structural parameters, energies, thermodynamic parameters and the NBO charges of BDHSe were determined by the DFT method. The 1H and 13C isotropic chemical shifts (δ ppm) of BDHSe with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. SHG experiment was carried out using Kurtz-Perry powder technique. The efficiency of second harmonic generation for BDHSe was estimated relatively to KDP: deff = 0.97 deff (KDP).

  15. Chemical insight from density functional modeling of molecular adsorption: Tracking the bonding and diffusion of anthracene derivatives on Cu(111) with molecular orbitals

    Science.gov (United States)

    Wyrick, Jonathan; Einstein, T. L.; Bartels, Ludwig

    2015-03-01

    We present a method of analyzing the results of density functional modeling of molecular adsorption in terms of an analogue of molecular orbitals. This approach permits intuitive chemical insight into the adsorption process. Applied to a set of anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow the electronic states of the molecules that are involved in the bonding process and correlate them to both the molecular adsorption geometry and the species' diffusive behavior. We additionally provide computational code to easily repeat this analysis on any system.

  16. Chemical Synthesis of the 20 kDa Heme Protein Nitrophorin 4 by α-Ketoacid-Hydroxylamine (KAHA) Ligation.

    Science.gov (United States)

    He, Chunmao; Kulkarni, Sameer S; Thuaud, Frédéric; Bode, Jeffrey W

    2015-10-26

    The chemical synthesis of the 184-residue ferric heme-binding protein nitrophorin 4 was accomplished by sequential couplings of five unprotected peptide segments using α-ketoacid-hydroxylamine (KAHA) ligation reactions. The fully assembled protein was folded to its native structure and coordinated to the ferric heme b cofactor. The synthetic holoprotein, despite four homoserine residues at the ligation sites, showed identical properties to the wild-type protein in nitric oxide binding and nitrite dismutase reactivity. This work establishes the KAHA ligation as a valuable and viable approach for the chemical synthesis of proteins up to 20 kDa and demonstrates that it is well-suited for the preparation of hydrophobic protein targets. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Molecular Electronics

    DEFF Research Database (Denmark)

    Jennum, Karsten Stein

    This thesis includes the synthesis and characterisation of organic compounds designed for molecular electronics. The synthesised organic molecules are mainly based on two motifs, the obigo(phenyleneethynylenes) (OPE)s and tetrathiafulvalene (TTF) as shown below. These two scaffolds (OPE and TTF......) are chemically merged together to form cruciform-like structures that are an essential part of the thesis. The cruciform molecules were subjected to molecular conductance measurements to explore their capability towards single-crystal field-effect transistors (Part 1), molecular wires, and single electron......, however, was obtained by a study of a single molecular transistor. The investigated OPE5-TTF compound was captured in a three-terminal experiment, whereby manipulation of the molecule’s electronic spin was possible in different charge states. Thus, we demonstrated how the cruciform molecules could...

  18. Synthesis and Physical and Chemical Properties of Hypergolic Chemicals such as N,N,N-Trimethylhydrazinium and 1-Ethyl-4-Methyl-1,2,4-Triazolium Salts

    Directory of Open Access Journals (Sweden)

    Young-Seok Kim

    2015-12-01

    Full Text Available Hypergolic chemicals N,N,N-trimethylhydrazinium iodide, [TMH]+[I]−, and 1-ethyl-4-methyl-1,2,4-triazolium iodide, [EMT]+[I]− were firstly synthesized by nucleophilic substitution (SN2. The successful synthesis of hypergolic chemicals [TMH]+[I]− and [EMT]+[I]− was confirmed by IR and 1H-NMR spectroscopy and, GC-mass spectrometry. Subsequently the hypergolic chemicals [TMH]+[X]− (X = CN−, N3−, NO3−, NO2−, ClO4−, AlCl4− were prepared via an ion exchange reaction from [TMH]+[I]− and [EMT]+[I]−, respectively. After that, a mixture of hypergolic chemicals was prepared by dissolving the synthesized hypergolic chemicals in 2-hydroxyethylhydrazine (HOCH2CH2NHNH2. The physical and chemical properties of the mixture such as decomposition temperature (Td, density (d, viscosity (η, and decomposition energy (ΔHd was then evaluated to determine suitability for use as liquid rocket fuels. The ignition delay (ID time of the mixture of hypergolic chemicals with [TMH]+[N3]− and [TMH]+[CN]− using H2O2 as an oxidizer was determined as 55.6 ms and 97.4 ms; respectively. The ID time of the mixture of hypergolic chemicals with [EMT]+[N3]−; [EMT]+[CN]−; [EMT]+[AlCl4]−; and [EMT]+[I]− using H2O2 as an oxidizer was also determined as 18.0 ms; 32.6 ms; 27.6 ms; and 7.96 ms; respectively. The synthesized mixture of hypergolic chemicals could thus be used as a rocket propellant liquid fuel.

  19. The role of the chemical composition of monetite on the synthesis and properties of α-tricalcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, Jo, E-mail: jo.duncan@abdn.ac.uk [Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE (United Kingdom); MacDonald, James F., E-mail: J.F.MacDonald@warwick.ac.uk [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Hanna, John V., E-mail: J.V.Hanna@warwick.ac.uk [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Shirosaki, Yuki, E-mail: yukis@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima, Kita-ku, Okayama 700-8530 (Japan); Hayakawa, Satoshi, E-mail: satoshi@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima, Kita-ku, Okayama 700-8530 (Japan); Osaka, Akiyoshi, E-mail: a-osaka@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima, Kita-ku, Okayama 700-8530 (Japan); Skakle, Janet M.S., E-mail: j.skakle@abdn.ac.uk [Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE (United Kingdom); Gibson, Iain R., E-mail: i.r.gibson@abdn.ac.uk [Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE (United Kingdom); School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD (United Kingdom)

    2014-01-01

    There has been a resurgence of interest in alpha-tricalcium phosphate (α-TCP), with use in cements, polymer composites and in bi- and tri-phasic calcium phosphate bone grafts. The simplest and most established method for preparing α-TCP is the solid state reaction of monetite (CaHPO{sub 4}) and calcium carbonate at high temperatures, followed by quenching. In this study, the effect of the chemical composition of reagents used in the synthesis of α-TCP on the local structure of the final product is reported and findings previously reported pertaining to the phase composition and stability are also corroborated. Chemical impurities in the monetite reagents were identified and could be correlated to the calcium phosphate products formed; magnesium impurities favoured the formation of β-TCP, whereas single phase α-TCP was favoured when magnesium levels were low. Monetite synthesised in-house exhibited a high level of chemical purity; when this source was used to produce an α-TCP sample, the α-polymorph could be obtained by both quenching and by cooling to room temperature in the furnace at rates between 1 and 10 °C/min, thereby simplifying the synthesis process. It was only when impurities were minimised that the 12 phosphorus environments in the α-TCP structure could be resolved by {sup 31}P nuclear magnetic resonance; samples containing chemical impurity showed differing degrees of line-broadening. Reagent purity should therefore be considered a priority when synthesising/characterising the α-polymorph of TCP. - Highlights: • Most commercial sources of monetite contain impurities that affect synthesis of phase pure α-TCP. • Ratio of α:β-TCP polymorphs formed by solid state reaction is dependent on reactant chemical purity. • If reagents in α-TCP synthesis are chemically pure, quenching is not required to obtain α-polymorph. • 12 unique P sites in α-TCP were only fully realised by {sup 31}P NMR when chemically pure reagents are used.

  20. Synthesis and characterization of CoPt nanoparticles prepared by room temperature chemical reduction with PAMAM dendrimer as template.

    Science.gov (United States)

    Wan, Haiying; Shi, Shifan; Bai, Litao; Shamsuzzoha, Mohammad; Harrell, J W; Street, Shane C

    2010-08-01

    We describe an approach to synthesize monodisperse CoPt nanoparticles with dendrimer as template by a simple chemical reduction method in aqueous solution using NaBH4 as reducing agent at room temperature. The as-made CoPt nanoparticles buried in the dendrimer matrix have the chemically disordered fcc structure and can be transformed to the fct phase after annealing at 700 degrees C. This is the first report of dendrimer-mediated room temperature synthesis of monodisperse magnetic nanoparticles in aqueous solution.

  1. Chemical and Electrochemical Synthesis of Polypyrrole Using Carrageenan as a Dopant: Polypyrrole/Multi-Walled Carbon Nanotube Nanocomposites

    Directory of Open Access Journals (Sweden)

    Mostafizur Rahaman

    2018-06-01

    Full Text Available In this article, iota-carrageenan (IC and kappa-carrageenan (KC are used as dopants for the chemical and electrochemical synthesis of polypyrrole (PPy. The composites of chemically synthesized PPy with multi-walled carbon nanotubes (MWNTs were prepared using an in situ technique. Both the dialyzed and non-dialyzed IC and KC were used as dopants for electrochemical polymerization of pyrrole. Chemically synthesized PPy and PPy/MWNTs composites were studied by ultraviolet visible (UV-vis absorption spectra to investigate the effect of the concentration and the incorporation of MWNTs. In addition, the electrical, thermal, mechanical, and microscopic characterizations of these films were performed to examine the effect of the dopants and MWNTs on these properties, along with their surface morphology. The films of electrochemically polymerized PPy were characterized using UV-vis absorption spectra, scanning electron microscopy, and cyclic voltammetry (CV. The results were then compared with the chemical polymerized PPy.

  2. Synthesis of molecular imprinting polymers for extraction of gallic acid from urine.

    Science.gov (United States)

    Bhawani, Showkat Ahmad; Sen, Tham Soon; Ibrahim, Mohammad Nasir Mohammad

    2018-02-21

    The molecularly imprinted polymers for gallic acid were synthesized by precipitation polymerization. During the process of synthesis a non-covalent approach was used for the interaction of template and monomer. In the polymerization process, gallic acid was used as a template, acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker and 2,2'-azobisisobutyronitrile as an initiator and acetonitrile as a solvent. The synthesized imprinted and non-imprinted polymer particles were characterized by using Fourier-transform infrared spectroscopy and scanning electron microscopy. The rebinding efficiency of synthesized polymer particles was evaluated by batch binding assay. The highly selective imprinted polymer for gallic acid was MIPI1 with a composition (molar ratio) of 1:4:20, template: monomer: cross-linker, respectively. The MIPI1 showed highest binding efficiency (79.50%) as compared to other imprinted and non-imprinted polymers. The highly selective imprinted polymers have successfully extracted about 80% of gallic acid from spiked urine sample.

  3. Synthesis, Molecular Modelling and Biological Evaluation of Novel Heterodimeric, Multiple Ligands Targeting Cholinesterases and Amyloid Beta

    Directory of Open Access Journals (Sweden)

    Michalina Hebda

    2016-03-01

    Full Text Available Cholinesterases and amyloid beta are one of the major biological targets in the search for a new and efficacious treatment of Alzheimer’s disease. The study describes synthesis and pharmacological evaluation of new compounds designed as dual binding site acetylcholinesterase inhibitors. Among the synthesized compounds, two deserve special attention—compounds 42 and 13. The former is a saccharin derivative and the most potent and selective acetylcholinesterase inhibitor (EeAChE IC50 = 70 nM. Isoindoline-1,3-dione derivative 13 displays balanced inhibitory potency against acetyl- and butyrylcholinesterase (BuChE (EeAChE IC50 = 0.76 μM, EqBuChE IC50 = 0.618 μM, and it inhibits amyloid beta aggregation (35.8% at 10 μM. Kinetic studies show that the developed compounds act as mixed or non-competitive acetylcholinesterase inhibitors. According to molecular modelling studies, they are able to interact with both catalytic and peripheral active sites of the acetylcholinesterase. Their ability to cross the blood-brain barrier (BBB was confirmed in vitro in the parallel artificial membrane permeability BBB assay. These compounds can be used as a solid starting point for further development of novel multifunctional ligands as potential anti-Alzheimer’s agents.

  4. Synthesis, cytotoxicity and molecular modelling studies of new phenylcinnamide derivatives as potent inhibitors of cholinesterases.

    Science.gov (United States)

    Saeed, Aamer; Mahesar, Parvez Ali; Zaib, Sumera; Khan, Muhammad Siraj; Matin, Abdul; Shahid, Mohammad; Iqbal, Jamshed

    2014-05-06

    The present study reports the synthesis of cinnamide derivatives and their biological activity as inhibitors of both cholinesterases and anticancer agents. Controlled inhibition of brain acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) may slow neurodegeneration in Alzheimer's diseases (AD). The anticholinesterase activity of phenylcinnamide derivatives was determined against Electric Eel acetylcholinesterase (EeAChE) and horse serum butyrylcholinesterase (hBChE) and some of the compounds appeared as moderately potent inhibitors of EeAChE and hBChE. The compound 3-(2-(Benzyloxy)phenyl)-N-(3,4,5-trimethoxyphenyl)acrylamide (3i) showed maximum activity against EeAChE with an IC50 0.29 ± 0.21 μM whereas 3-(2-chloro-6-nitrophenyl)-N-(3,4,5-trimethoxyphenyl)acrylamide (3k) was proved to be the most potent inhibitor of hBChE having IC50 1.18 ± 1.31 μM. To better understand the enzyme-inhibitor interaction of the most active compounds toward cholinesterases, molecular modelling studies were carried out on high-resolution crystallographic structures. The anticancer effects of synthesized compounds were also evaluated against cancer cell line (lung carcinoma). The compounds may be useful leads for the design of a new class of anticancer drugs for the treatment of cancer and cholinesterase inhibitors for Alzheimer's disease (AD). Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  5. Synthesis, Biological Evaluation, and Molecular Modeling Studies of New Oxadiazole-Stilbene Hybrids against Phytopathogenic Fungi

    Science.gov (United States)

    Jian, Weilin; He, Daohang; Song, Shaoyun

    2016-08-01

    Natural stilbenes (especially resveratrol) play important roles in plant protection by acting as both constitutive and inducible defenses. However, their exogenous applications on crops as fungicidal agents are challenged by their oxidative degradation and limited availability. In this study, a new class of resveratrol-inspired oxadiazole-stilbene hybrids was synthesized via Wittig-Horner reaction. Bioassay results indicated that some of the compounds exhibited potent fungicidal activity against Botrytis cinerea in vitro. Among these stilbene hybrids, compounds 11 showed promising inhibitory activity with the EC50 value of 144.6 μg/mL, which was superior to that of resveratrol (315.6 μg/mL). Remarkably, the considerably abnormal mycelial morphology was observed in the presence of compound 11. The inhibitory profile was further proposed by homology modeling and molecular docking studies, which showed the possible interaction of resveratrol and oxadiazole-stilbene hybrids with the cytochrome P450-dependent sterol 14α-demethylase from B. cinerea (BcCYP51) for the first time. Taken together, these results would provide new insights into the fungicidal mechanism of stilbenes, as well as an important clue for biology-oriented synthesis of stilbene hybrids with improved bioactivity against plant pathogenic fungi in crop protection.

  6. Synthesis, molecular modeling and biological evaluation of PSB as targeted antibiotics.

    Science.gov (United States)

    Cheng, Kui; Zheng, Qing-Zhong; Hou, Jin; Zhou, Yang; Liu, Chang-Hong; Zhao, Jing; Zhu, Hai-Liang

    2010-04-01

    We described here the design, synthesis, molecular modeling, and biological evaluation of a series of peptide and Schiff bases (PSB) small molecules, inhibitors of Escherichia coli beta-Ketoacyl-acyl carrier protein synthase III (ecKAS III). The initial lead compound was reported by us previously, we continued to carry out structure-activity relationship studies and optimize the lead structure to potent inhibitors in this research. The results demonstrated that both N-(2-(3,5-dichloro-2-hydroxybenzylideneamino)propyl)-2-hydroxybenzamide (1f) and 2-hydroxy-N-(2-(2-hydroxy-5-iodobenzylideneamino)propyl)-4-methylbenzamide (3e) posses good ecKAS III inhibitory activity and well binding affinities by bonding Gly152/Gly209 of ecKAS III and fit into the mouth of the substrate tunnel, and can be as potential antibiotics agent, displaying minimal inhibitory concentration values in the range 0.20-3.13microg/mL and 0.39-3.13microg/mL against various bacteria. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Synthesis and Characterization of Nanocrystalline Aluminophosphate AlPO4-5 Molecular Sieve

    Directory of Open Access Journals (Sweden)

    Asir Alnaama

    2018-03-01

    Full Text Available Nanocrystalline aluminophosphate AlPO4-5 molecular sieves were synthesized by hydrothermal method (HTS. Synthesis parameters like time and temperature of crystallization were investigated. Type of template (R and ratio of R/P2O5 were studied also. Characterization of the synthesized AlPO4-5 were done by powder X-ray diffraction (XRD, scanning electron microscopy (SEM/EDX, Fourier transform infrared (FTIR, differential scanning calorimetry-thermogravimetry analysis (DSC-TGA, and N2 adsorption-desorption BET analysis. XRD patterns results showed excellent crystallinity for two types of templates, di-n-propylamine (DPA and tetrapropyl ammonium hydroxide (TPAOH for alumminophosphate five (AFI structure. Nano-level for particle size of 66 nm was revealed by AFM test. Good thermal stability was obtained in DSC-TGA results. Best time and temperature of crystallization of 24h and 190 O C were got. Optimum R/P2O5 for two kind of template was established.

  8. Unscheduled DNA synthesis in human hair follicles after in vitro exposure to 11 chemicals: comparison with unscheduled DNA synthesis in rat hepatocytes.

    Science.gov (United States)

    van Erp, Y H; Koopmans, M J; Heirbaut, P R; van der Hoeven, J C; Weterings, P J

    1992-06-01

    A new method is described to investigate unscheduled DNA synthesis (UDS) in human tissue after exposure in vitro: the human hair follicle. A histological technique was applied to assess cytotoxicity and UDS in the same hair follicle cells. UDS induction was examined for 11 chemicals and the results were compared with literature findings for UDS in rat hepatocytes. Most chemicals inducing UDS in rat hepatocytes raised DNA repair at comparable concentrations in the hair follicle. However, 1 of 9 chemicals that gave a positive response in the rat hepatocyte UDS test, 2-acetylaminofluorene, failed to induce DNA repair in the hair follicle. Metabolizing potential of hair follicle cells was shown in experiments with indirectly acting compounds, i.e., benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine. The results support the conclusion that the test in its present state is valuable as a screening assay for the detection of unscheduled DNA synthesis. Moreover, the use of human tissues may result in a better extrapolation to man.

  9. Synthesis, molecular modeling and structural characterization of vanillin derivatives as antimicrobial agents

    Science.gov (United States)

    Sun, Juan; Yin, Yong; Sheng, Gui-Hua; Yang, Zhi-Bo; Zhu, Hai-Liang

    2013-05-01

    Two vanillin derivatives have been designed and synthesized and their biological activities were also evaluated for antimicrobial activity. Their chemical structures are characterized by single crystal X-ray diffraction studies, 1H NMR, MS, and elemental analysis. Structural stabilization of them followed by intramolecular as well as intermolecular H-bonds makes these molecules as perfect examples in molecular recognition with self-complementary donor and acceptor units within a single molecule. Docking simulations have been performed to position compounds into the FtsZ active site to determine their probable binding model. Compound 3a shows the most potent biological activity, which may be a promising antimicrobial leading compound for the further research.

  10. Influence of ionizing radiation on synthesis and molecular heterogeneity of catalase in tissue culture of Rauwolfia serpentina

    International Nuclear Information System (INIS)

    Komov, V.P.; Bespalova, E.V.; Strelkova, M.A.

    1998-01-01

    Changes in activity and molecular heterogeneity of catalase in tissue culture of Rauwolfia serpentina following irradiation in early growth period at the doses of 8 and 50 Gy has been studied. Ionizing radiation accelerate the synthesis and degradation rates of catalase and total protein. A comparative study of changes in enzyme and protein turnover during growth on irradiated and non-irradiated medium has been made [ru

  11. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. AYOUB KANAANI. Articles written in Journal of Chemical Sciences. Volume 128 Issue 8 August 2016 pp 1211-1221 Regular Article. Synthesis, molecular structure, spectroscopic investigations and computational study of a potential molecular switch of 2-([1 ...

  12. Process Parameters for Successful Synthesis of Carbon Nanotubes by Chemical Vapor Deposition: Implications for Chemical Mechanisms and Life-cycle Assessment

    Science.gov (United States)

    Xue, Ke

    Manufacturing of carbon nanotubes (CNTs) via chemical vapor deposition (CVD) calls for thermal treatment associated with gas-phase rearrangement and catalyst deposition to achieve high cost efficiency and limited influence on environmental impact. Taking advantage of higher degree of structure control and economical efficiency, catalytic chemical vapor deposition (CCVD) has currently become the most prevailing synthesis approach for the synthesis of large-scale pure CNTs in past years. Because the synthesis process of CNTs dominates the potential ecotoxic impacts, materials consumption, energy consumption and greenhouse gas emissions should be further limited to efficiently reduce life cycle ecotoxicity of carbon naotubes. However, efforts to reduce energy and material requirements in synthesis of CNTs by CCVD are hindered by a lack of mechanistic understanding. In this thesis, the effect of operating parameters, especially the temperature, carbon source concentration, and residence time on the synthesis were studied to improve the production efficiency in a different angle. Thus, implications on the choice of operating parameters could be provided to help the synthesis of carbon nanotubes. Here, we investigated the typical operating parameters in conditions that have yielded successful CNT production in the published academic literature of over seventy articles. The data were filtered by quality of the resultant product and deemed either "successful" or "unsuccessful" according to the authors. Furthermore, growth rate data were tabulated and used as performance metric for the process whenever possible. The data provided us an opportunity to prompt possible and common methods for practioners in the synthesis of CNTs and motivate routes to achieve energy and material minimization. The statistical analysis revealed that methane and ethylene often rely on thermal conversion process to form direct carbon precursor; further, methane and ethylene could not be the direct

  13. Synthesis, physical-chemical and biological properties of 7-benzyl-3-methyl-8-thioxanthine derivatives

    Directory of Open Access Journals (Sweden)

    D. H. Ivanchenko

    2017-12-01

    Full Text Available Introduction . Interest to the problem of creating new effective antimicrobial agents among xanthine derivatives does not decrease. Primarily, this is due to the increasing of microbial resistance to conventional antimicrobial agents and the emergence of their new strains. In recent years interest to the therapeutic use of antioxidants in the treatment of diseases associated with oxidative stress has increased. The aim of this work is to elaborate simple laboratory methods of 7-benzyl-3-methyl-8-thioxanthine derivatives synthesis, unspecified in scientific papers earlier, and to study their physical, chemical and biological properties. Materials and methods. The melting point has been determined with the help of an open capillary method with PTP-M device. Elemental analysis has been performed with the help of the instrument Elementar Vario L cube, NMR-spectra have been taken on a spectrometer Bruker SF-400 (operating frequency of 400 MHz, solvent DMSO, internal standard – TMS. Study of antimicrobial and antifungal activity of synthesized compounds has been performed by two-fold serial dilution method. Standard test strains have been used for the study: Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 885-653. Dimethylsulfoxide was used as the solvent of the compounds. Results. Under short-time heating up of the initial 7-benzyl-3-methyl-8-thioxanthine with alkyl, alkenyl, benzyl halides or heteroalkylchlorides in a water-propanol-2 mixture in the presence of an equimolar amount of sodium hydroxide leads to the formation of 8-S-substituted of 7-benzyl-3-methylxanthines. Structure of synthesized compounds was definitely proved by NMR-spectroscopy. We conducted primary screening research of antimicrobial activity of 7-benzyl-3-methyl-8-thioxanthine derivatives, which revealed moderate and weak activity in concentrations 50-100 mcg/ml. Most of the obtained compounds showed a

  14. Potent New Small-Molecule Inhibitor of Botulinum Neurotoxin Serotype A Endopeptidase Developed by Synthesis-Based Computer-Aided Molecular Design

    Science.gov (United States)

    2009-11-01

    simulations; (4) synthesis and evaluation of the molecules from Step 2 or 3 (e.g., synthesizing and testing AHP). From synthetic chemistry point of view...2000) Synthesis of 6H-indolo [2,3-b][1,6]naphthyridines and related compounds as the 5-Aza analogues of ellipticine alkaloids . J Org Chem 65: 7977–7983...Potent New Small-Molecule Inhibitor of Botulinum Neurotoxin Serotype A Endopeptidase Developed by Synthesis -Based Computer-Aided Molecular Design

  15. Molecular dynamics approaches to the design and synthesis of PCB targeting molecularly imprinted polymers: interference to monomer-template interactions in imprinting of 1,2,3-trichlorobenzene.

    Science.gov (United States)

    Cleland, Dougal; Olsson, Gustaf D; Karlsson, Björn C G; Nicholls, Ian A; McCluskey, Adam

    2014-02-07

    The interactions between each component of the pre-polymerisation mixtures used in the synthesis of molecularly imprinted polymers (MIP) specific for 1,2,3,4,5-pentachlorobenzene (1) and 1,2,3-trichlorobenzene (2) were examined in four molecular dynamics simulations. These simulations revealed that the relative frequency of functional monomer-template (FM-T) interactions was consistent with results obtained by the synthesis and evaluation of the actual MIPs. The higher frequency of 1 interaction with trimethylstyrene (TMS; 54.7%) than 1 interaction with pentafluorostyrene (PFS; 44.7%) correlated with a higher imprinting factor (IF) of 2.1 vs. 1.7 for each functional monomer respectively. The higher frequency of PFS interactions with 2 (29.6%) than TMS interactions with 2 (1.9%) also correlated well with the observed differences in IF (3.7) of 2 MIPs imprinted using PFS as the FM than the IF (2.8) of 2 MIPs imprinted using TMS as the FM. The TMS-1 interaction dominated the molecular simulation due to high interaction energies, but the weaker TMS-2 resulted in low interaction maintenance, and thus lower IF values. Examination of the other pre-polymerisation mixture components revealed that the low levels of TMS-2 interaction was, in part, due to interference caused by the cross linker (CL) ethyleneglycol dimethylacrylate (EGDMA) interactions with TMS. The main reason was, however, attributed to MeOH interactions with TMS in both a hydrogen bond and perpendicular configuration. This positioned a MeOH directly above the π-orbital of all TMS for an average of 63.8% of MD2 creating significant interference to π-π stacking interactions between 2 and TMS. These findings are consistent with the deviation from the 'normal' molecularly imprinted polymer synthesis ratio of 1 : 4 : 20 (T : FM : CL) of 20 : 1 : 29 and 15 : 6 : 29 observed with 2 and TMS and PFS respectively. Our molecular dynamics simulations correctly predicted the high level

  16. Synthesis and characterization of sugar based low molecular weight gelators and the preparation of chiral sulfinamides

    Science.gov (United States)

    Mangunuru, Hari Prasad Reddy

    Low molecular weight gelators (LMWGs) have received considerable attention in the field of chemistry from last few decades. These compounds form self-assembled fibrous networks like micelles, cylindrical, sheets, fibers, layers and so on. The fibrous network entraps the solvent and forms gel, because of the self-assembly phenomenon and their demonstrated potential uses in a variety of areas, ranging from environmental to medicinal applications. Sugars are good starting materials to synthesize the new class of LMWG's, because these are different from some expensive materials, these are natural products. We have synthesized and characterized the LMGS's based on D-glucose and D-glucosamine. D-glucosamine is the versatile starting material to make different peptoids and triazoles. Several series of compounds were synthesized using compounds 1-3 as starting material and studied the gelation behavior all the compounds. We have studied the self-assembling properties of a new class of tripeptoids, synthesized by one-pot Ugi reaction from simple starting materials. Among the focused library of tripeptoids synthesized, we found that several efficient low molecular weight organogelators were obtained for aqueous DMSO and ethanol mixtures. We have also synthesized and characterized a series of monosaccharide triazole derivatives. These compounds were synthesized from N-acetyl glucosamine and D-glucose via a Cu(I) catalyzed azide/alkyne cycloaddition reaction (CuAAc). The compounds have been screened for their gelation properties and several efficient low molecular weight organo/hydro gelators were obtained, among these compounds, five per-acetyl glucosamine derivatives and one peracetyl glucose derivative were able to form gels in water. These new molecules are expected to be useful in drug delivery and tissue engineering.*. Asymmetric synthesis of chiral amines is a challenging in synthetic organic chemistry. The development of new catalysts for asymmetric organic

  17. Synthesis and characterization of high molecular weight hydrophobically modified polyacrylamide nanolatexes using novel nonionic polymerizable surfactants

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2013-12-01

    Full Text Available In this article, nine hydrophobically modified polyacrylamides (HM-PAM nanolatexes, were synthesized by copolymerizing the acrylamide monomer and novel polymerizable surfactants (surfmers. The reaction was carried out by inverse microemulsion copolymerization technique. The copolymerization was initiated by redox initiators composed of potassium peroxodisulphate and sodium bisulfite. The emulsion was stabilized using mixed tween 85 and span 80 as nonionic emulsifiers. The prepared HM-PAMs were classified into three groups according to the surfmers used in the copolymerization. The chemical structures of the prepared HM-PAMs were confirmed by FT-IR, 1H NMR and 13C NMR. The thermal properties were estimated with the thermal gravimetric analysis (TGA. The size and morphology of the prepared latexes were investigated by the dynamic light scattering (DLS and the High Resolution Transmission Electron Microscope (HRTEM. Finally, the molecular weights of the prepared copolymers were determined by the GPC and the viscosity average molecular weight method. They were situated between 1.58 × 106 and 0.89 × 106.

  18. Synthesis Characterization and Decomposition Studies of tris[N-N-dibenzyidithocarbaso)Indium (III) Chemical Spray Deposition of Polycrystalline CuInS2 on Copper Films

    Science.gov (United States)

    Hehemann, David G.; Lau, J. Eva; Harris, Jerry D.; Hoops, Michael D.; Duffy, Norman V.

    2005-01-01

    This paper presents the results of the synthesis characterization and decomposition studies of tris[N-N-dibenzyidithocarbaso)Indium (III) with chemical spray deposition of polycrystalline CuInS2 on Copper Films.

  19. Complete chemical transformation of a molecular film by subexcitation electrons (<3 eV).

    Science.gov (United States)

    Balog, Richard; Illenberger, Eugen

    2003-11-21

    The potential of slow electrons to act as a soft tool to control a chemical reaction in the condensed phase is demonstrated. By setting the energy of a well defined electron beam to values below 3 eV, the surface of a thin film of 1,2-C(2)F(4)C(l2) molecules can completely be transformed into molecular chlorine (and by-products, possibly perfluorinated polymers). At higher energies (>6 eV) some equilibrium state between product and educt composition can be achieved, however, accompanied by a gradual overall degradation of the film. The effect of complete transformation is based on both the selectivity and particular energy dependence of the initial step of the reaction which is dissociative electron attachment to C(2)F(4)C(l2), but also the fact that the initial molecule is efficiently decomposed by subexcitation electrons while the product C(l2) is virtually unaffected.

  20. Molecular dynamics simulation of chemical sputtering of hydrogen atom on layer structured graphite

    International Nuclear Information System (INIS)

    Ito, A.; Wang, Y.; Irle, S.; Morokuma, K.; Nakamura, H.

    2008-10-01

    Chemical sputtering of hydrogen atom on graphite was simulated using molecular dynamics. Especially, the layer structure of the graphite was maintained by interlayer intermolecular interaction. Three kinds of graphite surfaces, flat (0 0 0 1) surface, armchair (1 1 2-bar 0) surface and zigzag (1 0 1-bar 0) surface, are dealt with as targets of hydrogen atom bombardment. In the case of the flat surface, graphene layers were peeled off one by one and yielded molecules had chain structures. On the other hand, C 2 H 2 and H 2 are dominant yielded molecules on the armchair and zigzag surfaces, respectively. In addition, the interaction of a single hydrogen isotope on a single graphene is investigated. Adsorption, reflection and penetration rates are obtained as functions of incident energy and explain hydrogen retention on layered graphite. (author)

  1. Chemical intermediate detection following corona discharge on volatile organic compounds: general method using molecular beam techniques

    International Nuclear Information System (INIS)

    He Luning; Sulkes, Mark

    2011-01-01

    Nonthermal plasma (NTP)-based treatments of volatile organic compounds (VOCs) have potential for effective environmental remediation. Theory and experiment that consider the basic science pertaining to discharge events have helped improve NTP remediation outcomes. If direct information on early post-discharge chemical intermediates were also available, it would likely lead to additional improvement in NTP remediation outcomes. To this point, however, experiments yielding direct information on post-NTP VOC intermediates have been limited. An approach using supersonic expansion molecular beam methods offers general promise for detection of post-discharge VOC intermediates. To illustrate the potential utility of these methods, we present mass spectra showing the growth of early products formed when pulsed corona discharges were carried out on toluene in He and then in He with added O 2 . Good general detection of neutral post-discharge species was obtained using 800 nm 150 fs photoionization pulses.

  2. Controlled fabrication of the strong emission YVO4:Eu3+ nanoparticles and nanowires by microwave assisted chemical synthesis

    International Nuclear Information System (INIS)

    Huong, Tran Thu; Vinh, Le Thi; Phuong, Ha Thi; Khuyen, Hoang Thi; Anh, Tran Kim; Tu, Vu Duc; Minh, Le Quoc

    2016-01-01

    In this report, we are presenting the controlled fabrication results of the strong emission YVO 4 : Eu 3+ nanoparticles and nanowires by microwave which is assisted chemical synthesis. The effects of incorporated synthesis conditions such as microwave irradiated powers, pH values and concentration of chemical composition on properties of nanomaterials are also investigated to obtain the controllable size and homogenous morphology. Morphological and optical properties of YVO 4 : Eu 3+ prepared products which have been characterized by X-ray diffraction (XRD), field emission micrcroscopy (FESEM) and photoluminescence spectroscopy. As based from result of synthesized samples, we found that the changing of pH values, microwave irradiated powers and chemical composition rise to change reform the size and shape of materials from nanoparticles (diameter about 20 nm) to wires shape (with about 500÷800 nm length and 10÷20 nm width). The photoluminescence (PL) spectroscopy measurements of YVO 4 : Eu 3+ nanostructure materials under UV excitation showed that: the strong luminescence in red region with narrow lines corresponding to the intra-4f transitions of 5 D 0 – 7 F j (j=1, 2, 3, and 4) of Eu 3+ ions with the highest luminescence intensity of 5 D 0 → 7 F 2 transition. - Highlights: • The strong emission YVO 4 :Eu 3+ nanostructure materials were successfully synthesized by microwave assisted chemical synthesis. • The size, morphology and luminescence of the YVO 4 :Eu 3+ nanostructure materials can be controlled by the solution pH, microwave irradiated powers and chemical composition. • These YVO 4 :Eu 3+ nanostructure materials above can potentially applied in various fields of application, especially in luminescent labeling and visualization in biomedical application.

  3. Post-irradiation chemical reactions during devitrification of molecular matrices (review)

    International Nuclear Information System (INIS)

    Barkalov, I.M.; Kiryukhin, D.P.

    1993-01-01

    At temperatures above the melting point (mp) a material is in a thermodynamic equilibrium state, in which any thermodynamic function of state (specific volume, enthalpy, and entrophy) is governed unambiguously by the temperature, pressure, etc. At temperatures below the mp, the material is converted to another equilibrium state, i.e., a crystal. However, during rapid cooling, a state of a nonequilibrium supercooled liquid can be obtained. Further cooling of this state below the glass-transition temperature, T g1 , leads to the additional formation of a nonequilibrium solid amorphous state, often simply called glass. In the vitreous state, species are capable of only vibrational and small-scale rotational motions. The translational mobility that is characteristic of the liquid state is completely lost. Very important for what follows is the fact that the transition from a supercooled liquid to the vitreous state or the reverse transition (devitrification) is accompanied by a sharp change of properties: the viscosity changes by 10-15 orders of magnitude, the modulus of elasticity changes 10-1000 fold, the coefficient of thermal expansion changes 10-100 fold, etc. Most impressive is the gigantic viscosity jump in the narrow temperature-dependent glass-transition region. This means that the molecular mobility governing the chemical-transformation dynamics undergoes a sharp change in this region. The nature of the chemical process during passage through the glass-softening region should change because of a sharp change of the mobility of the reactants, with a huge change of molecular mobility being attained by a temperature change of only a few degrees. During radiolysis of vitreous matrices, active species of radical and ionic nature are formed. This review discusses the recombination reactions of radiolysis products during heating to the supercooled state

  4. Chemical analysis and genotoxicity of high molecular mass PAH in sediment samples and biota

    International Nuclear Information System (INIS)

    McCarry, B.E.; Marvin, C.H.; Smith, R.W.; Bryant, D.W.

    1995-01-01

    A normal phase liquid chromatography (NPLC) method was used to fractionate the organic extracts of prepared from coal tar-contaminated sediments from hamilton Harbor in Ontario and from Sydney Harbor in Nova Scotia into molecular mass classes. Each PAH fraction up to 302 amu was analyzed by GC-MS and fractions containing PAH with molecular masses greater than 302 amu were analyzed by atmospheric pressure chemical ionization (APCI) LC-MS.Each fraction was also subjected to Ames bioassays using a TA100-like strain of Salmonella typhimurium (YG1025 + S9). The 300/302 amu, 326/328 and 350/352 amu PAH fractions accounted for 25% of the total genotoxic response of the extract; these PAH constitute a substantial genotoxic burden. A number of 300, 302, 326, 350, 374 and 400 amu PAH were identified using APCI LC-MS and comparison with authentic standards. The non-polar aromatic extracts of bottom sediments, suspended sediments and zebra mussels from Hamilton Harbor were also examined by GC-MS, APCI LC-MS and genotoxicity bioassays. The profiles of the priority and high mass PAH in these samples were identical showing that all PAH up to and exceeding 400 amu were readily bioavailable to biota such as Zebra mussels. In addition, the pseudo faeces of the Zebra mussels and amphipod detritivores which fed on the pseudo faeces had chemical profiles identical to the Zebra mussels. Since many sport fish prize amphipods as food, this observation demonstrates a pathway for organic contaminants adsorbed to suspended sediments to enter the food chain of non-bottom-feeding fish in areas infested by Zebra mussels

  5. Synthesis and characterization of nano ZnO rods via microwave assisted chemical precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Uma Sangari, N., E-mail: umasangariselvakumar@gmail.com [Department of Chemistry, S.F.R. College for Women, Sivakasi 626123 (India); Chitra Devi, S. [Department of Chemistry, S.F.R. College for Women, Sivakasi 626123 (India)

    2013-01-15

    A microwave assisted chemical precipitation method has been employed for the synthesis of nano zinc oxide rods by reacting zinc nitrate and potassium hydroxide. The amount of potassium hydroxide was adjusted for three different pHs to achieve ZnO nano rods with varying aspect ratio. The mechanism of growth of nano rods is explained briefly. The average crystallite size of the as synthesized samples was analyzed by means of powder XRD pattern and estimated to vary from 25.6 nm to 43.1 nm. The existence of rods was confirmed using scanning electron microscopy (SEM). The samples were also analyzed using FT-IR. The optical properties of the samples were also studied by means of UV-visible spectra and Room Temperature Photo Luminescence studies. The band gap of the samples was determined from the DRS spectrum. A strong near band emission peaks due to surface defects are observed in the PL spectrum. - Graphical abstract: At the solution pH of 11 and 9, tetrapod-like and flower-like ZnO nano rods were formed along with separated rods respectively due to the formation of activated nuclei of different sizes. Highlights: Black-Right-Pointing-Pointer Increase in alkalinity of the precursor solution results in longer rods. Black-Right-Pointing-Pointer Beyond a saturation limit, the excess of added OH{sup -} ions inhibited the growth of rods. Black-Right-Pointing-Pointer Keeping all parameters the same, the alkalinity can only modify the aspect ratio of the rods and not their morphology.

  6. Microwave plasma chemical synthesis of nanocrystalline carbon film structures and study their properties

    Science.gov (United States)

    Bushuev, N.; Yafarov, R.; Timoshenkov, V.; Orlov, S.; Starykh, D.

    2015-08-01

    The self-organization effect of diamond nanocrystals in polymer-graphite and carbon films is detected. The carbon materials deposition was carried from ethanol vapors out at low pressure using a highly non-equilibrium microwave plasma. Deposition processes of carbon film structures (diamond, graphite, graphene) is defined. Deposition processes of nanocrystalline structures containing diamond and graphite phases in different volume ratios is identified. The solid film was obtained under different conditions of microwave plasma chemical synthesis. We investigated the electrical properties of the nanocrystalline carbon films and identified it's from various factors. Influence of diamond-graphite film deposition mode in non-equilibrium microwave plasma at low pressure on emission characteristics was established. This effect is justified using the cluster model of the structure of amorphous carbon. It was shown that the reduction of bound hydrogen in carbon structures leads to a decrease in the threshold electric field of emission from 20-30 V/m to 5 V/m. Reducing the operating voltage field emission can improve mechanical stability of the synthesized film diamond-graphite emitters. Current density emission at least 20 A/cm2 was obtained. Nanocrystalline carbon film materials can be used to create a variety of functional elements in micro- and nanoelectronics and photonics such as cold electron source for emission in vacuum devices, photonic devices, cathodoluminescent flat display, highly efficient white light sources. The obtained graphene carbon net structure (with a net size about 6 μm) may be used for the manufacture of large-area transparent electrode for solar cells and cathodoluminescent light sources

  7. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Guo, Wenlong [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Hongji, E-mail: hongjili@yeah.net [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Xu, Sheng [School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072 (China); Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2014-10-30

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na{sub 2}SO{sub 4} aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g{sup −1} at current density of 0.5 A g{sup −1}. The capacitance remains at about 84% after 1000 cycles at 10 A g{sup −1}. The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices.

  8. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    International Nuclear Information System (INIS)

    Li, Mingji; Guo, Wenlong; Li, Hongji; Xu, Sheng; Qu, Changqing; Yang, Baohe

    2014-01-01

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na 2 SO 4 aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g −1 at current density of 0.5 A g −1 . The capacitance remains at about 84% after 1000 cycles at 10 A g −1 . The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices

  9. Chemical Genetics — A Versatile Method to Combine Science and Higher Level Teaching in Molecular Genetics

    Directory of Open Access Journals (Sweden)

    Björn Sandrock

    2012-10-01

    Full Text Available Phosphorylation is a key event in many cellular processes like cell cycle, transformation of environmental signals to transcriptional activation or polar growth. The chemical genetics approach can be used to analyse the effect of highly specific inhibition in vivo and is a promising method to screen for kinase targets. We have used this approach to study the role of the germinal centre kinase Don3 during the cell division in the phytopathogenic fungus Ustilago maydis. Due to the easy determination of the don3 phenotype we have chosen this approach for a genetic course for M.Sc. students and for IMPRS (International Max-Planck research school students. According to the principle of “problem-based learning” the aim of this two-week course is to transfer knowledge about the broad spectrum of kinases to the students and that the students acquire the ability to design their own analog-sensitive kinase of interest. In addition to these training goals, we benefit from these annual courses the synthesis of basic constructs for genetic modification of several kinases in our model system U. maydis.

  10. Strategies of molecular imprinting-based fluorescence sensors for chemical and biological analysis.

    Science.gov (United States)

    Yang, Qian; Li, Jinhua; Wang, Xiaoyan; Peng, Hailong; Xiong, Hua; Chen, Lingxin

    2018-07-30

    One pressing concern today is to construct sensors that can withstand various disturbances for highly selective and sensitive detecting trace analytes in complicated samples. Molecularly imprinted polymers (MIPs) with tailor-made binding sites are preferred to be recognition elements in sensors for effective targets detection, and fluorescence measurement assists in highly sensitive detection and user-friendly control. Accordingly, molecular imprinting-based fluorescence sensors (MI-FL sensors) have attracted great research interest in many fields such as chemical and biological analysis. Herein, we comprehensively review the recent advances in MI-FL sensors construction and applications, giving insights on sensing principles and signal transduction mechanisms, focusing on general construction strategies for intrinsically fluorescent or nonfluorescent analytes and improvement strategies in sensing performance, particularly in sensitivity. Construction strategies are well overviewed, mainly including the traditional indirect methods of competitive binding against pre-bound fluorescent indicators, employment of fluorescent functional monomers and embedding of fluorescence substances, and novel rational designs of hierarchical architecture (core-shell/hollow and mesoporous structures), post-imprinting modification, and ratiometric fluorescence detection. Furthermore, MI-FL sensor based microdevices are discussed, involving micromotors, test strips and microfluidics, which are more portable for rapid point-of-care detection and in-field diagnosing. Finally, the current challenges and future perspectives of MI-FL sensors are proposed. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Document authentication at molecular levels using desorption atmospheric pressure chemical ionization mass spectrometry imaging.

    Science.gov (United States)

    Li, Ming; Jia, Bin; Ding, Liying; Hong, Feng; Ouyang, Yongzhong; Chen, Rui; Zhou, Shumin; Chen, Huanwen; Fang, Xiang

    2013-09-01

    Molecular images of documents were obtained by sequentially scanning the surface of the document using desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS), which was operated in either a gasless, solvent-free or methanol vapor-assisted mode. The decay process of the ink used for handwriting was monitored by following the signal intensities recorded by DAPCI-MS. Handwritings made using four types of inks on four kinds of paper surfaces were tested. By studying the dynamic decay of the inks, DAPCI-MS imaging differentiated a 10-min old from two 4 h old samples. Non-destructive forensic analysis of forged signatures either handwritten or computer-assisted was achieved according to the difference of the contour in DAPCI images, which was attributed to the strength personalized by different writers. Distinction of the order of writing/stamping on documents and detection of illegal printings were accomplished with a spatial resolution of about 140 µm. A Matlab® written program was developed to facilitate the visualization of the similarity between signature images obtained by DAPCI-MS. The experimental results show that DAPCI-MS imaging provides rich information at the molecular level and thus can be used for the reliable document analysis in forensic applications. © 2013 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons, Ltd.

  12. Application of molecular beam mass spectrometry to chemical vapor deposition studies

    International Nuclear Information System (INIS)

    Hsu, W.L.; Tung, D.M.

    1992-01-01

    A molecular beam mass spectrometer system has been designed and constructed for the specific purpose of measuring the gaseous composition of the vapor environment during chemical vapor deposition of diamond. By the intrinsic nature of mass analysis, this type of design is adaptable to a broad range of other applications that rely either on thermal- or plasma-induced chemical kinetics. When gas is sampled at a relatively high process pressure (∼2700 Pa for our case), supersonic gas expansion at the sampling orifice can cause the detected signals to have a complicated dependence on the operating conditions. A comprehensive discussion is given on the effect of gas expansion on mass discrimination and signal scaling with sampling pressure and temperature, and how these obstacles can be overcome. This paper demonstrates that radical species can be detected with a sensitivity better than 10 ppm by the use of threshold ionization. A detailed procedure is described whereby one can achieve quantitative analysis of the detected species with an accuracy of ±20%. This paper ends with an example on the detection of H, H 2 , CH 3 , CH 4 , and C 2 H 2 during diamond growth

  13. Reactions driving conformational movements (molecular motors) in gels: conformational and structural chemical kinetics.

    Science.gov (United States)

    Otero, Toribio F

    2017-01-18

    In this perspective the empirical kinetics of conducting polymers exchanging anions and solvent during electrochemical reactions to get dense reactive gels is reviewed. The reaction drives conformational movements of the chains (molecular motors), exchange of ions and solvent with the electrolyte and structural (relaxation, swelling, shrinking and compaction) gel changes. Reaction-driven structural changes are identified and quantified from electrochemical responses. The empirical reaction activation energy (E a ), the reaction coefficient (k) and the reaction orders (α and β) change as a function of the conformational energy variation during the reaction. This conformational energy becomes an empirical magnitude. E a , k, α and β include and provide quantitative conformational and structural information. The chemical kinetics becomes structural chemical kinetics (SCK) for reactions driving conformational movements of the reactants. The electrochemically stimulated conformational relaxation model describes empirical results and some results from the literature for biochemical reactions. In parallel the development of an emerging technological world of soft, wet, multifunctional and biomimetic tools and anthropomorphic robots driven by reactions of the constitutive material, as in biological organs, can be now envisaged being theoretically supported by the kinetic model.

  14. MODELING THE ATOMIC-TO-MOLECULAR TRANSITION AND CHEMICAL DISTRIBUTIONS OF TURBULENT STAR-FORMING CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Offner, Stella S. R. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Bisbas, Thomas G.; Viti, Serena [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6B (United Kingdom); Bell, Tom A., E-mail: stella.offner@yale.edu [Centro de Astrobiologia (CSIC-INTA), Carretera de Ajalvir, km 4, E-28850 Madrid (Spain)

    2013-06-10

    We use 3D-PDR, a three-dimensional astrochemistry code for modeling photodissociation regions (PDRs), to post-process hydrodynamic simulations of turbulent, star-forming clouds. We focus on the transition from atomic to molecular gas, with specific attention to the formation and distribution of H, C{sup +}, C, H{sub 2}, and CO. First, we demonstrate that the details of the cloud chemistry and our conclusions are insensitive to the simulation spatial resolution, to the resolution at the cloud edge, and to the ray angular resolution. We then investigate the effect of geometry and simulation parameters on chemical abundances and find weak dependence on cloud morphology as dictated by gravity and turbulent Mach number. For a uniform external radiation field, we find similar distributions to those derived using a one-dimensional PDR code. However, we demonstrate that a three-dimensional treatment is necessary for a spatially varying external field, and we caution against using one-dimensional treatments for non-symmetric problems. We compare our results with the work of Glover et al., who self-consistently followed the time evolution of molecule formation in hydrodynamic simulations using a reduced chemical network. In general, we find good agreement with this in situ approach for C and CO abundances. However, the temperature and H{sub 2} abundances are discrepant in the boundary regions (A{sub v} {<=} 5), which is due to the different number of rays used by the two approaches.

  15. Synthesis and evaluation of germanium organometallic compounds as precursors for chemical vapor deposition (CVD) and for obtaining nanoparticles of elemental germanium

    International Nuclear Information System (INIS)

    Ballestero Martinez, Ernesto

    2014-01-01

    The interest in the development of materials having applications such as electronics areas or biomarkers has affected the synthesis of new compounds based on germanium. This element has had two common oxidation states, +4 and +2, of them, +2 oxidation state has been the least studied and more reactive. Additionally, compounds of germanium (II) have had similarities with carbenes regarding the chemical acid-base Lewis. The preparation of compounds of germanium (II) with ligands β-decimations has enabled stabilization of new chemical functionalities and, simultaneously, provided interesting thermal properties to develop new preparation methodologies of materials with novel properties. The preparation of amides germanium(II) L'Ge(NHPh) [1, L' = {HC (CMeN-2,4,6-Me 3 C 6 H 2 ) 2 }], L'Ge(4-NHPy) [2] L'Ge(2-NHPy) [3] and LGe(2-NHPy) [4, L = {HC(CMeN-2,6- i Pr 2 C 6 H 3 ) 2 }]; the structural chemical composition were determined using techniques such as nuclear magnetic resonance ( 1 H, 13 C), other techniques are treated: elemental analysis, melting point, infrared spectroscopy, X-ray diffraction of single crystal and thermal gravimetric analysis (TGA). The TGA has showed that 4-1 have experimented a thermal decomposition; therefore, these compounds could be considered as potential starting materials for obtaining germanium nitride (GeN x ). Certainly, the availability of nitrogen coordinating atoms in the chemical composition in 2-4 have been interesting because it could act as ligands in reactions with transition metal complexes. That way, information could be obtained at the molecular level for some reactions and interactions that in surface chemistry have used similar link sites, for example, chemical functionalization of silicon and germanium substrates. The synthesis and structural characterization of germanium chloride compound(II) L''GeCl [5, L'' = HC{(CMe) (N-2,6-Me 2 C 6 H 3 )} 2 ], which could be used later for the

  16. Enzymes as modular catalysts for redox half-reactions in H2-powered chemical synthesis: from biology to technology.

    Science.gov (United States)

    Reeve, Holly A; Ash, Philip A; Park, HyunSeo; Huang, Ailun; Posidias, Michalis; Tomlinson, Chloe; Lenz, Oliver; Vincent, Kylie A

    2017-01-15

    The present study considers the ways in which redox enzyme modules are coupled in living cells for linking reductive and oxidative half-reactions, and then reviews examples in which this concept can be exploited technologically in applications of coupled enzyme pairs. We discuss many examples in which enzymes are interfaced with electronically conductive particles to build up heterogeneous catalytic systems in an approach which could be termed synthetic biochemistry We focus on reactions involving the H + /H 2 redox couple catalysed by NiFe hydrogenase moieties in conjunction with other biocatalysed reactions to assemble systems directed towards synthesis of specialised chemicals, chemical building blocks or bio-derived fuel molecules. We review our work in which this approach is applied in designing enzyme-modified particles for H 2 -driven recycling of the nicotinamide cofactor NADH to provide a clean cofactor source for applications of NADH-dependent enzymes in chemical synthesis, presenting a combination of published and new work on these systems. We also consider related photobiocatalytic approaches for light-driven production of chemicals or H 2 as a fuel. We emphasise the techniques available for understanding detailed catalytic properties of the enzymes responsible for individual redox half-reactions, and the importance of a fundamental understanding of the enzyme characteristics in enabling effective applications of redox biocatalysis. © 2017 The Author(s).

  17. Synthesis and Supramolecular Chemistry of Novel Liquid Crystalline Crown Ether-Substituted Phthalocyanines : Toward Molecular Wires and Molecular Ionoelectronics

    NARCIS (Netherlands)

    Nostrum, Cornelus F. van; Picken, Stephen J.; Schouten, Arend-Jan; Nolte, Roeland J.M.

    1995-01-01

    The synthesis of the metal-free and the dihydroxysilicon derivatives of tetrakis[4’,5’-bis(decoxy)benzo-18-crown-6]phthalocyanine is described. The metal-free phthalocyanine is liquid crystalline and exhibits a crystalline phase to mesophase transition at 148 °C. The structures of the crystalline

  18. Design and synthesis of single-source molecular precursors to homogeneous multi-component oxide materials

    Science.gov (United States)

    Fujdala, Kyle Lee

    This dissertation describes the syntheses of single-source molecular precursors to multi-component oxide materials. These molecules possess a core metal or element with various combinations of -OSi(O tBu)3, -O2P(OtBu) 2, and -OB[OSi(OtBu)3] 2 ligands. Such molecules decompose under mild thermolytic conditions (models for oxide-supported metal species and multi-component oxides. Significantly, the first complexes to contain three or more heteroelements suitable for use in the TMP method have been synthesized. Compounds for use as single-source molecular precursors have been synthesized containing Al, B, Cr, Hf, Mo, V, W, and Zr, and their thermal transformations have been examined. Heterogeneous catalytic reactions have been examined for selected materials. Also, cothermolyses of molecular precursors and additional molecules (i.e., metal alkoxides) have been utilized to provide materials with several components for potential use as catalysts or catalyst supports. Reactions of one and two equivs of HOSi(OtBu) 3 with Cr(OtBu)4 afforded the first Cr(IV) alkoxysiloxy complexes (tBuO) 3CrOSi(OtBu)3 and ( tBuO)2Cr[OSi(OtBu) 3]2, respectively. The high-yielding, convenient synthesis of (tBuO)3CrOSi(O tBu)3 make this complex a useful single-source molecular precursor, via the TMP method, to Cr/Si/O materials. The thermal transformations of (tBuO)3CrOSi(O tBu)3 and (tBuO) 2Cr[OSi(OtBu)3]2 to chromia-silica materials occurr at low temperatures (≤180°C), to give isobutene as the major carbon-containing product. The material generated from the solid-state conversion of (tBuO) 3CrOSi(OtBu)3 (CrOS ss) has an unexpectedly high surface area of 315 m2 g-1 that is slightly reduced to 275 m2 g-1 after calcination at 500°C in O2. The xerogel obtained by the thermolysis of an n-octane solution of (tBuO)3CrOSi(O tBu)3 (CrOSixg) has a surface area of 315 m2 g-1 that is reduced to 205 m2 g-1 upon calcination at 500°C. Powder X-ray diffraction (PXRD) analysis revealed that Cr2O 3 is

  19. Solvent effect on the synthesis of clarithromycin: A molecular dynamics study

    Science.gov (United States)

    Duran, Dilek; Aviyente, Viktorya; Baysal, Canan

    2004-02-01

    Clarithromycin (6- O-methylerythromycin A) is a 14-membered macrolide antibiotic which is active in vitro against clinically important gram-positive and gram-negative bacteria. The selectivity of the methylation of the C-6 OH group is studied on erythromycin A derivatives. To understand the effect of the solvent on the methylation process, detailed molecular dynamics (MD) simulations are performed in pure DMSO, pure THF and DMSO:THF (1:1) mixture by using the anions at the C-6, C-11 and C-12 positions of 2',4''-[ O-bis(TMS)]erythromycin A 9-[ O-(dimethylthexylsilyl)oxime] under the assumption that the anions are stable on the sub-nanosecond time scale. The conformations of the anions are not affected by the presence of the solvent mixture. The radial distribution functions are computed for the distribution of different solvent molecules around the `O-' of the anions. At distances shorter than 5 Å, DMSO molecules are found to cluster around the C-11 anion, whereas the anion at the C-12 position is surrounded by the THF molecules. The anion at the C-6 position is not blocked by the solvent molecules. The results are consistent with the experimental finding that the methylation yield at the latter position is increased in the presence of a DMSO:THF (1:1) solvent mixture. Thus, the effect of the solvent in enhancing the yield during the synthesis is not by changing the conformational properties of the anions, but rather by creating a suitable environment for methylation at the C-6 position.

  20. Synthesis and Evaluation of CO2 Thickeners Designed with Molecular Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Robert Enick; Erick Beckman; J. Karl Johnson

    2009-08-31

    The objective of this research was to use molecular modeling techniques, coupled with our prior experimental results, to design, synthesize and evaluate inexpensive, non-fluorous carbon dioxide thickening agents. The first type of thickener that was considered was associating polymers. Typically, these thickeners are copolymers that contain a highly CO{sub 2}-philic monomer, and a small concentration of a CO{sub 2}-phobic associating monomer. Yale University was solely responsible for the synthesis of a second type of thickener; small, hydrogen bonding compounds. These molecules have a core that contains one or more hydrogen-bonding groups, such as urea or amide groups. Non-fluorous, CO{sub 2}-philic functional groups were attached to the hydrogen bonding core of the compound to impart CO{sub 2} stability and macromolecular stability to the linear 'stack' of these compounds. The third type of compound initially considered for this investigation was CO{sub 2}-soluble surfactants. These surfactants contain conventional ionic head groups and composed of CO{sub 2}-philic oligomers (short polymers) or small compounds (sugar acetates) previously identified by our research team. Mobility reduction could occur as these surfactant solutions contacted reservoir brine and formed mobility control foams in-situ. The vast majority of the work conducted in this study was devoted to the copolymeric thickeners and the small hydrogen-bonding thickeners; these thickeners were intended to dissolve completely in CO{sub 2} and increase the fluid viscosity. A small but important amount of work was done establishing the groundwork for CO{sub 2}-soluble surfactants that reduced mobility by generating foams in-situ as the CO{sub 2}+surfactant solution mixed with in-situ brine.

  1. Synthesis of Sub-10 nm Two-Dimensional Covalent Organic Thin Film with Sharp Molecular Sieving Nanofiltration

    KAUST Repository

    Gadwal, Ikhlas

    2018-04-06

    We demonstrated here a novel and facile synthesis of two-dimensional (2D) covalent organic thin film with pore size around 1.5 nm using a planar, amphiphilic and substituted heptacyclic truxene based triamine and a simple dialdehyde as building blocks by dynamic imine bond formation at the air/water interface using Langmuir–Blodgett (LB) method. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), all unanimously showed the formation of large, molecularly thin and free-standing membrane that can be easily transferred on different substrate surfaces. The 2D membrane supported on a porous polysulfone showed a rejection rate of 64 and 71% for NaCl and MgSO4, respectively, and a clear molecular sieving at molecular size around 1.3 nm, which demonstrated a great potential in the application of pretreatment of seawater desalination and separation of organic molecules.

  2. Microwave radiation hydrothermal synthesis and characterization of micro- and mesoporous composite molecular sieve Y/SBA-15

    Directory of Open Access Journals (Sweden)

    Wenyuan Wu

    2017-05-01

    Full Text Available A microwave radiation hydrothermal method to control synthesis of micro- and mesoporous Y/SBA-15 composite molecular sieves was reported. The synthesized SBA-15 and Y/SBA-15 were characterized by scanning electron microscopy (SEM and N2 adsorption–desorption. The three kinds of different concentrations of hydrochloric acid (0.75 M, 2 M and 3.25 M were used to investigate the effect on Y/SBA-15. The analysis results of the composite products indicated that the optimization synthesis condition employed zeolite type Y and TEOS as silicon sources under 0.75 M hydrochloric acid by the microwave radiation hydrothermal synthesis method. The N2 adsorption–desorption test results of micro–mesoporous composite molecular sieve type Y/SBA-15 in mesoporous extent indicated that SBET is 355.529 m2/g, D‾BET is 4.050 nm, and mesoporous aperture focuses on the distribution region of 5.3 nm. It was found that the received composite product has an appropriate proportion of smaller size, larger size pore structure and the thicker pore wall. In addition, its internal channels have a high degree of order and smooth flow in long-range channels.

  3. Synthesis of Monodispersed Spherical Single Crystalline Silver Particles by Wet Chemical Process; Shisshiki kagakuho ni yoru tanbunsankyujo tankesshoginryushi no gose

    Energy Technology Data Exchange (ETDEWEB)

    Ueyama, Ryousuke.; Harada, Masahiro.; Ueyama, Tamotsu.; Harada, Akio. [Daiken Chemistry Industry Corporation, Osaka (Japan); Yamamoto, Takashi. [National Defence Academy, Kanagawa (Japan). Dept. of Electrical Engineering; Shiosaki, Tadashi. [Nara Institute of Science and Technology, Nara (Japan). Graduate School of Materials Science; Kuribayashi, Kiyoshi. [Teikyo University of Science and Technology, Yamanashi (Japan). Dept. of Materials

    1999-01-01

    Ultrafine silver monodispersed particle were prepared by wet chemical process. To decrease the reduction speed, an important factor in generating monodispersed particles is to control the following three factors: synthesis temperature, concentration of aggregation-relaxing agent added, and concentration of silver nitrate solution. Synthesis of monodispersed spherical Ag particles, used as metal powders for electrode, became possible using the nucleus grouwth reaction method. This process also allowed the control of the diameter of the powder particles. The silver particles were distributed in ta narrow particle diameter range with on average of 0.5 {mu}m. Transmission electron microscopy (TEM) revealed that single-crystalline silver particles were prepared by the present method. (author)

  4. Bringing the science of proteins into the realm of organic chemistry: total chemical synthesis of SEP (synthetic erythropoiesis protein).

    Science.gov (United States)

    Kent, Stephen B H

    2013-11-11

    Erythropoietin, commonly known as EPO, is a glycoprotein hormone that stimulates the production of red blood cells. Recombinant EPO has been described as "arguably the most successful drug spawned by the revolution in recombinant DNA technology". Recently, the EPO glycoprotein molecule has re-emerged as a major target of synthetic organic chemistry. In this article I will give an account of an important body of earlier work on the chemical synthesis of a designed EPO analogue that had full biological activity and improved pharmacokinetic properties. The design and synthesis of this "synthetic erythropoiesis protein" was ahead of its time, but has gained new relevance in recent months. Here I will document the story of one of the major accomplishments of synthetic chemistry in a more complete way than is possible in the primary literature, and put the work in its contemporaneous context. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Carbon 13 nuclear magnetic resonance chemical shifts empiric calculations of polymers by multi linear regression and molecular modeling

    International Nuclear Information System (INIS)

    Da Silva Pinto, P.S.; Eustache, R.P.; Audenaert, M.; Bernassau, J.M.

    1996-01-01

    This work deals with carbon 13 nuclear magnetic resonance chemical shifts empiric calculations by multi linear regression and molecular modeling. The multi linear regression is indeed one way to obtain an equation able to describe the behaviour of the chemical shift for some molecules which are in the data base (rigid molecules with carbons). The methodology consists of structures describer parameters definition which can be bound to carbon 13 chemical shift known for these molecules. Then, the linear regression is used to determine the equation significant parameters. This one can be extrapolated to molecules which presents some resemblances with those of the data base. (O.L.). 20 refs., 4 figs., 1 tab

  6. Chemical control of the characteristics of Mo-doped carbon xerogels by surfactant-mediated synthesis

    Czech Academy of Sciences Publication Activity Database

    Maldonado-Hódar, F. J.; Jirglová, Hana; Pérez-Cadenas, A. F.; Morales-Torres, S.

    2013-01-01

    Roč. 51, JAN 2013 (2013), s. 213-223 ISSN 0008-6223 Institutional support: RVO:61388955 Keywords : synthesis * molybdenum * carbon xerogels Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.160, year: 2013

  7. Transformation from layered to tunnel structures: Synthesis, characterization, and applications of manganese oxide octahedral molecular sieves

    Science.gov (United States)

    Xia, Guan-Guang

    Manganese oxide based octahedral molecular sieves (OMS) have been found to have a wide variety of applications as catalysts, absorbents, and battery materials due to their unique structures and physical and chemical properties. OMS materials are made up of manganese oxide octahedral building blocks sharing comers and edges to form tunnel structures. Manganese species in the framework of OMS materials are mixed valent with various ion-exchangeable cations residing in the tunnels playing important roles in charge balancing and special chemical activities. With different synthetic parameters such as the template used, temperature, pressure, and the pH of the synthetic media, layered birnessite materials were hydrothermally transformed into distinct tunnel structures with different tunnel sizes, including Mg-3x3 (OMS-1), NH4-2x2 (NH4-OMS-2), Na-2x4 (OMS-5), and other manganese oxides. Characterization of the OMS materials with a wide variety of instruments has revealed that most of them are nano-fibrous hollow crystals ith large surface areas, high ion-exchange capabilities, and relatively high thermal stabilities. The Na-2x4 tunnel structure sodium MnOx has been synthesized for the first time and studied in detail, including synthetic strategies, structural analyses, and other physical and chemical property analyses. As catalysts, the synthetic OMS materials show high catalytic activities and shape-selective properties. For example, the results of the competitive oxidation of cycloalkanes with tertiary butyl hydrogen peroxide (TBHP) over different tunnel sized ONIS materials have proven that the OMS materials with larger tunnels are more favorable for the oxidation of the biggest molecule, cyclooctane, than the smallest one, cyclohexane. Besides the tunnel size effects, tunnel cations in the OMS materials also have influences on their catalytic activities. The study of carbon monoxide cleanup for fuel cell applications demonstrates that Ag-OMS-2 (a hollandite

  8. Synthesis of silver nanoparticles by chemical reduction at various fraction of MSA and their structure characterization

    Energy Technology Data Exchange (ETDEWEB)

    Diantoro, Markus, E-mail: m-diantoror@yahoo.com; Fitrianingsih, Rina, E-mail: m-diantoror@yahoo.com; Mufti, Nandang, E-mail: m-diantoror@yahoo.com; Fuad, Abdulloh, E-mail: m-diantoror@yahoo.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang (UM), Jl. Semarang No. 5 Malang 65145 (Indonesia)

    2014-03-24

    Nanosilver is currently one of the most common engineered nanomaterials and is used in many applications that lead to the release of silver nanoparticles and silver ions into aqueous systems. Nanosilver also possesses enhanced antimicrobial activity and bioavailability that may less environmental risk compared with other manufactured nanomaterials. Described in this research are the synthesis of silver nanoparticle produced by chemical reduction from silver nitrate (AgNO{sub 3}) solution. As a reducing agent, Sodium Borohydride (NaBH{sub 4}) was used and mercaptosuccinic Acid (MSA) as stabilizer to prevent the nanoparticle from aglomerating. It was also used two kinds of solvent, they are water and methanol. In typical experiment MSA was dissolve in methanol with a number of variation of molarity i.e. 0,03 M, 0,06 M, 0,12 M, 0,15 M, and the mixture was kept under vigorous stirring in an ice bath. A solution of silver nitrate of 340 mg in 6,792 ml water was added. A freshly prepared aqueous solution of sodium borohydride (756,6 mL in 100 mL of water) was added drop wisely. The solution was kept for half an hour for stirring and were allowed to settle down in methanol. The obtained samples then characterized by means of x-ray diffractometer, and scanning electron microscopy, as well as transmission electron microscopy to obtain their structures of silver nanoparticles, morphology, and sizes. It is shown that diameter of silver nanoparticle sized about 24.3 nm (Ag@MSA 0.03 M), 20.4 nm (Ag@MSA 0.06 M), 16.8 nm (Ag@MSA 0.12 M), 16.9 nm (Ag@MSA 0.15 M) which was calculated by Scherrer formula by taking the FWHM from fitting to Gaussian. The phases and lattice parameter showed that there is no significant change in its volume by increasing molarity of stabilizer. In contrast, the size of particles is decreasing.

  9. Synthesis and evaluation of germanic organometallic compounds as precursors for chemical vapor deposition (CVD) and for obtaining nanoparticles of elemental germanium

    International Nuclear Information System (INIS)

    Ballestero Martinez, Ernesto

    2014-01-01

    The interest in the development of materials that have applications in areas such as electronics or biomarkers has affected the synthesis of new compounds based on germanium. This element has two states of common oxidation, +4 and +2, of them, the +2 oxidation state is the least studied and more reactive. Additionally, compounds of germanium (II) have similarities to carbenes in terms Lewis'acid base chemistry. The preparation of compounds of germanium (II) with ligands β-diketiminates has made possible the stabilization of new chemical functionalities and, simultaneously, it has provided interesting thermal properties to develop new methods of preparation of materials with novel properties. The preparation of amides germanium (II) L'Ge (NHPh) [1, L'= {HC (CMeN-2,4,6-Me 3 C 6 H 2 ) 2 } - ], L'Ge (4-NHPy) [2], L'Ge (2-NHPy) [3] and LGe(2-NHPy) [4, L = {HC (CMeN-2,6- i Pr 2 C 6 H 3 ) 2 ] - ] are presented, the chemical and structural composition was determined by using techniques such as nuclear magnetic resonance ( 1 H, 13 C), elemental analysis, melting point, infrared spectroscopy, X-ray diffraction of single crystal and thermogravimetric analysis (TGA). The TGA has demonstrated that 1-4 experience a thermal decomposition, therefore, these compounds could be considered as potential starting materials for the obtaining of germanium nitride (GeN x ). Certainly, the availability of coordinating nitrogen atoms in the chemical composition in 2-4 have been interesting given that it could act as ligands in reactions with transition metal complexes. Thus, relevant information to molecular level could be obtained for some reactions and interactions that have used similar link sites in surface chemistry, for example, the chemical functionalization of silicon and germanium substrate. Additionally, the synthesis and structural characterization of germanium chloride compound (II) L G eCl [5, L' = HC{(CMe) (N-2,6-Me 2 C 6 H 3 )} 2 - ] is reported

  10. Room temperature chemical synthesis of highly oriented PbSe nanotubes based on negative free energy of formation

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R., E-mail: brsankapal@rediffmail.com [Thin Film and Nano Science Laboratory, Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001 (MS) (India); Ladhe, R.D.; Salunkhe, D.B.; Baviskar, P.K. [Thin Film and Nano Science Laboratory, Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001 (MS) (India); Gupta, V.; Chand, S. [Organic and Hybrid Solar Cell, Physics of Energy Harvesting Division, Dr. K.S. Krishnan Marg, National Physical Laboratory, New Delhi 110012 (India)

    2011-10-13

    Highlights: > Simple, inexpensive and room temperature chemical synthesis route. > Highly oriented PbSe nanotubes from Cd(OH){sub 2} nanowires through lead hydroxination. > The process was template free without the use of any capping agent. > Reaction kinetics was accomplished due to more negative free energy of formation. > The ion exchange mechanism due to difference in the solubility products. - Abstract: The sacrificial template free chemical synthesis of PbSe nanotubes at room temperature has been performed by lead hydroxination from cadmium hydroxide nanowires. This process was based on the ion exchange reaction to replace Cd{sup 2+} with Pb{sup 2+} ions from hydroxyl group followed by replacement of hydroxyl group with selenium ions. The reaction kinetics was accomplished due to more negative free energy of formation and thus the difference in the solubility products. The formed nanotubes were inclusive of Pb and Se with proper inter-chemical bonds with preferred orientations having diameter in tens of nanometer. These nanotubes can have future applications in electronic, optoelectronics and photovoltaic's as well.

  11. Room temperature chemical synthesis of highly oriented PbSe nanotubes based on negative free energy of formation

    International Nuclear Information System (INIS)

    Sankapal, B.R.; Ladhe, R.D.; Salunkhe, D.B.; Baviskar, P.K.; Gupta, V.; Chand, S.

    2011-01-01

    Highlights: → Simple, inexpensive and room temperature chemical synthesis route. → Highly oriented PbSe nanotubes from Cd(OH) 2 nanowires through lead hydroxination. → The process was template free without the use of any capping agent. → Reaction kinetics was accomplished due to more negative free energy of formation. → The ion exchange mechanism due to difference in the solubility products. - Abstract: The sacrificial template free chemical synthesis of PbSe nanotubes at room temperature has been performed by lead hydroxination from cadmium hydroxide nanowires. This process was based on the ion exchange reaction to replace Cd 2+ with Pb 2+ ions from hydroxyl group followed by replacement of hydroxyl group with selenium ions. The reaction kinetics was accomplished due to more negative free energy of formation and thus the difference in the solubility products. The formed nanotubes were inclusive of Pb and Se with proper inter-chemical bonds with preferred orientations having diameter in tens of nanometer. These nanotubes can have future applications in electronic, optoelectronics and photovoltaic's as well.

  12. Report of National Cancer Institute symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. I. Common molecular mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Borg, D.C.

    1984-01-01

    Some aspects of molecular mechanisms common to radiation and chemical carcinogenesis are discussed, particularly the DNA damage done by these agents. Emphasis is placed on epidemiological considerations and on dose-response models used in risk assessment to extrapolate from experimental data obtained at high doses to the effects from long-term, low-level exposures. 3 references, 6 figures. (ACR)

  13. Report of National Cancer Institute symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. I. Common molecular mechanisms

    International Nuclear Information System (INIS)

    Borg, D.C.

    1984-01-01

    Some aspects of molecular mechanisms common to radiation and chemical carcinogenesis are discussed, particularly the DNA damage done by these agents. Emphasis is placed on epidemiological considerations and on dose-response models used in risk assessment to extrapolate from experimental data obtained at high doses to the effects from long-term, low-level exposures. 3 references, 6 figures

  14. Osmotic Pressure of Aqueous Electrolyte Solutions via Molecular Simulations of Chemical Potentials: Application to NaCl.

    Czech Academy of Sciences Publication Activity Database

    Smith, W.R.; Moučka, F.; Nezbeda, Ivo

    2016-01-01

    Roč. 407, Sl (2016), s. 76-83 ISSN 0378-3812 Grant - others:NSERC(CA) OGP1041 Institutional support: RVO:67985858 Keywords : osmotic pressure * chemical potential * molecular simulation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.473, year: 2016

  15. Quantum-chemical calculations and electron diffraction study of the equilibrium molecular structure of vitamin K3

    Science.gov (United States)

    Khaikin, L. S.; Tikhonov, D. S.; Grikina, O. E.; Rykov, A. N.; Stepanov, N. F.

    2014-05-01

    The equilibrium molecular structure of 2-methyl-1,4-naphthoquinone (vitamin K3) having C s symmetry is experimentally characterized for the first time by means of gas-phase electron diffraction using quantum-chemical calculations and data on the vibrational spectra of related compounds.

  16. HIGHLY SELECTIVE SENSORS FOR CHEMICAL AND BIOLOGICAL WARFARE AGENTS, INSECTICIDES AND VOCS BASED ON A MOLECULAR SURFACE IMPRINTING TECHNIQUE

    Science.gov (United States)

    Abstract was given as an oral platform presentation at the Pittsburgh Conference, Orlando FL (March 5-9, 2006). Research described is the development of sensors based on molecular surface imprinting. Applications include the monitoring of chemical and biological agents and inse...

  17. Synthesis and characterization of molecular materials from N-trifluoromethanesulfonyl-1-azahexa-1,3,5-trieno derivates

    International Nuclear Information System (INIS)

    Rodriguez Gomez, A; Ortiz Rebollo, A; Sanchez Vergara, M.E

    2008-01-01

    Molecular materials have been developed recently for their diverse electrical properties, such as insulation, semiconductors, conductors and superconductors and they can also be used in diodes, transistors, solar cells and electronic switches among other things. The molecular materials are formed by condensation and organization of molecular units that can be organic, organometallic, or metal-organic and whose properties are individually characterized later. Because of their true nature, the properties of molecular materials can be derived from the characteristics of the molecular units that form them. For this study molecular materials were synthesized from electronic donors and acceptors: Cu (TAAB) +2 , Ni (TAAB) +2 and the NTrifluoromethanesulfonyl-1-azahexa-1,3,5-trieno derivatives that are especially attractive from the structural point of view, since in their neutral from they have an extensive electronic dislocation which gives them a very specific chemical behavior. The synthesized materials were chemically and structurally characterized by IR spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and mass spectrometry. Thin films of the different materials were deposited and the optical activation energy was evaluated, using techniques like profilometry and UV-vis spectroscopy

  18. Synthesis of Fe–Li–Cr Multinuclear Complexes as Molecular Magnet Materials

    Directory of Open Access Journals (Sweden)

    Iis Siti Jahro

    2008-03-01

    Full Text Available Multinuclear complexes have received considerable interest as molecular magnet materials. Up to now, several complex compounds based on bidentate ligand 2,2’ bipyridine have been synthesized. In this research, the Fe-Li-Cr multinuclear complexes with derivative 2’2- bipyridine ligands: 2-(2’-pyridylquinoline(pq, 2,2’-Pyridil(pdl have been synthesized. The oxalate (ox ligand has also been used as a bridging ligand in these multinuclear complexes. The chemical formula of Li[FeCr(ox2(pq(BF42(H2O2] and [Fe(pdln][LiCr(ox3] complexes have been verified using metal and C, H, N elemental analysis data. The IR spectra in 350 – 4000 cm-1 range exhibit characteristic absorptions, which support the proposed structure of complex. The plausible structure of the compounds has been drawn based on complex formation mechanism. The magnetic susceptibility at room temperature of the pq-complex is about 5.7 BM and of the pdl- complexes are 4.8 and 5.5 BM. These indicated that both spin states of iron(II exist in the multinuclear complexes.

  19. Brassinosteroids: synthesis and biological activities

    Czech Academy of Sciences Publication Activity Database

    Oklešťková, Jana; Rárová, Lucie; Kvasnica, Miroslav; Strnad, Miroslav

    2015-01-01

    Roč. 14, č. 6 (2015), s. 1053-1072 ISSN 1568-7767 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Brassinosteroids * Chemical synthesis * Plant biological activity Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.686, year: 2015

  20. Mechanochemical synthesis of bumetanide-4-aminobenzoic acid molecular cocrystals: a facile and green approach to drug optimization.

    Science.gov (United States)

    Bruni, Giovanna; Maietta, Mariarosa; Berbenni, Vittorio; Mustarelli, Piercarlo; Ferrara, Chiara; Freccero, Mauro; Grande, Vincenzo; Maggi, Lauretta; Milanese, Chiara; Girella, Alessandro; Marini, Amedeo

    2014-08-07

    Molecular cocrystals are of growing interest in pharmaceutics for their improved physicochemical properties. Their mechanochemical synthesis is very promising, being easy, cheap, and "green". Here, for the first time, we report on cocrystallization of bumetanide, a diuretic and natriuretic active principle, and 4-aminobenzoic acid. The synthesis is performed both by wet and dry grinding. The cocrystal formation was investigated with a wide range of techniques, including solid-state NMR, IR, XRD, microscopy, and thermal analysis. Wet and dry grinding procedures led to different cocrystal polymorphs. In particular, the dry method gave a cocrystal by powder amorphization and subsequent crystallization. DFT calculations at the B3LYP/6-31+G(d,p) level of theory shed light on the H-bond scheme at the basis of cocrystal formation. The cocrystals showed improved solubility and dissolution rate with respect to the drug alone. This could guarantee a faster absorption and a better bioavailability of the active principle.

  1. Targeting acetylcholinesterase: identification of chemical leads by high throughput screening, structure determination and molecular modeling.

    Directory of Open Access Journals (Sweden)

    Lotta Berg

    Full Text Available Acetylcholinesterase (AChE is an essential enzyme that terminates cholinergic transmission by rapid hydrolysis of the neurotransmitter acetylcholine. Compounds inhibiting this enzyme can be used (inter alia to treat cholinergic deficiencies (e.g. in Alzheimer's disease, but may also act as dangerous toxins (e.g. nerve agents such as sarin. Treatment of nerve agent poisoning involves use of antidotes, small molecules capable of reactivating AChE. We have screened a collection of organic molecules to assess their ability to inhibit the enzymatic activity of AChE, aiming to find lead compounds for further optimization leading to drugs with increased efficacy and/or decreased side effects. 124 inhibitors were discovered, with considerable chemical diversity regarding size, polarity, flexibility and charge distribution. An extensive structure determination campaign resulted in a set of crystal structures of protein-ligand complexes. Overall, the ligands have substantial interactions with the peripheral anionic site of AChE, and the majority form additional interactions with the catalytic site (CAS. Reproduction of the bioactive conformation of six of the ligands using molecular docking simulations required modification of the default parameter settings of the docking software. The results show that docking-assisted structure-based design of AChE inhibitors is challenging and requires crystallographic support to obtain reliable results, at least with currently available software. The complex formed between C5685 and Mus musculus AChE (C5685•mAChE is a representative structure for the general binding mode of the determined structures. The CAS binding part of C5685 could not be structurally determined due to a disordered electron density map and the developed docking protocol was used to predict the binding modes of this part of the molecule. We believe that chemical modifications of our discovered inhibitors, biochemical and biophysical

  2. Alkynes as a versatile platform for construction of chemical molecular complexity and realization of molecular 3D printing

    International Nuclear Information System (INIS)

    Galkin, K I; Ananikov, V P

    2016-01-01

    The current level of scientific and technological development requires the formation of general tools and techniques. One of the most versatile technologies is 3D printing, which allows fast and efficient creation of materials and biological objects of desired shape and composition. Today, methods have been developed for 3D printing of macro- and nano-sized objects and for production of films and deposited materials with molecular precision but the most promising technology is printing at the molecular level (molecular 3D printing) for the purpose of direct construction of molecular complexity. This process is currently at the initial stage concerning selection of simple molecules to be used as building blocks possessing flexibility, availability and ease of modification. In this review, we examine the possible versatile synthons suitable for preparation of the main types of organic compounds using molecular 3D printing. The surveyed data strongly indicate that alkyne molecules may be used as a building material in a molecular 3D printer working on hydrocarbons. The bibliography includes 428 references

  3. A fast chemical route for the synthesis of TBHQ functionalized reduced graphene oxide and its electrochemical performances

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Subhasis; Sen, Pintu, E-mail: psen@vecc.gov.in; Bandyopadhyay, S.K.

    2016-02-01

    A fast chemical route for the synthesis of tertiary butyl hydroquinone (TBHQ) functionalized reduced graphene oxide (FRGO) and their application as high performance electrode materials for supercapacitors have been reported. Reductions of chemically exfoliated graphene oxides (GO) in the presence of small amount of TBHQ (1–2 wt % with respect to GO) at various time periods were investigated through XRD, FTIR and Raman studies. Reappearance of broad diffraction peak close to graphite peak (002) reveals an efficient method of reduction of different oxygen containing functional groups present in GO/FGO resulting in a decrease of interlayer d-spacing (∼3.5 Å). Absence of the absorption peaks in FTIR for –C=O, t-O–H, epoxide and alkoxy groups supports the complete reduction of GO to FRGO by hydrazine hydrate within a short time period of 4 h reduction under reflux condition. A large red shift in UV spectrum of FRGO – 4 h (270 nm) reveals the complete reduction of graphene oxide. The average crystallite sp{sup 2} domains sizes have been estimated through Raman spectroscopy. Plausible mechanism of TBHQ assisted fast chemical reduction of FGO has been enumerated. 1.5 wt % TBHQ in FRGO shows the best electrochemical performance where TBHQ not only acts as a reducing agent during functionalization, but also plays as an active redox molecule for enhanced capacitance of 200 F/g. - Highlights: • A fast chemical route has been adopted for the synthesis of TBHQ functionalized RGO. • The kinetics of chemical reduction becomes faster in the presence of TBHQ. • The FTIR spectrum of functionalized RGO supports the complete reduction process. • TBHQ also plays a vital role for enhancing capacitance of functionalized RGO.

  4. Synthesis of cerium oxide catalysts supported on MCM-41 molecular sieve; Sintese de catalisadores de oxido de cerio suportados na peneira molecular MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Souza, E.L.S.; Barros, T.R.B.; Sousa, B.V. de, E-mail: emylle.souza@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica

    2016-07-01

    Porous materials have been widely studied as catalysts and catalyst support. The MCM-41 structure is the one that has been most studied because of its application possibilities in chemical processes. This work aimed to obtain and characterize cerium oxide catalysts supported on MCM-41 molecular sieve. The molecular sieve was synthesized by the conventional method with the following molar composition: 1 SiO2: 0.30 CTABr: NH3 11: 144 H2O. Then, 25% w/w cerium was incorporated into the MCM-41 using the wet impregnation process and the material obtained was activated by calcination. From the XRD patterns was confirmed the structure of the molecular sieve, and were identified the cerium oxide phases in its structure. The textural catalysts characteristics were investigated by isotherms of N2 adsorption/desorption (BET method). (author)

  5. Chemical Topic Modeling: Exploring Molecular Data Sets Using a Common Text-Mining Approach.

    Science.gov (United States)

    Schneider, Nadine; Fechner, Nikolas; Landrum, Gregory A; Stiefl, Nikolaus

    2017-08-28

    Big data is one of the key transformative factors which increasingly influences all aspects of modern life. Although this transformation brings vast opportunities it also generates novel challenges, not the least of which is organizing and searching this data deluge. The field of medicinal chemistry is not different: more and more data are being generated, for instance, by technologies such as DNA encoded libraries, peptide libraries, text mining of large literature corpora, and new in silico enumeration methods. Handling those huge sets of molecules effectively is quite challenging and requires compromises that often come at the expense of the interpretability of the results. In order to find an intuitive and meaningful approach to organizing large molecular data sets, we adopted a probabilistic framework called "topic modeling" from the text-mining field. Here we present the first chemistry-related implementation of this method, which allows large molecule sets to be assigned to "chemical topics" and investigating the relationships between those. In this first study, we thoroughly evaluate this novel method in different experiments and discuss both its disadvantages and advantages. We show very promising results in reproducing human-assigned concepts using the approach to identify and retrieve chemical series from sets of molecules. We have also created an intuitive visualization of the chemical topics output by the algorithm. This is a huge benefit compared to other unsupervised machine-learning methods, like clustering, which are commonly used to group sets of molecules. Finally, we applied the new method to the 1.6 million molecules of the ChEMBL22 data set to test its robustness and efficiency. In about 1 h we built a 100-topic model of this large data set in which we could identify interesting topics like "proteins", "DNA", or "steroids". Along with this publication we provide our data sets and an open-source implementation of the new method (CheTo) which

  6. Synthesis of silver nanoparticles by radiolysis, photolysis and chemical reduction of AgNO3 in Hibiscus sabdariffa infusion (karkade)

    International Nuclear Information System (INIS)

    Cataldo, Franco; Ursini, Ornella; Angelini, Giancarlo

    2016-01-01

    Silver nanoparticles of different average diameters were synthesized by γ-radiolysis, UV-photolysis and chemical reduction of AgNO 3 solutions in Hibiscus sabdariffa infusion commonly known as 'karkade'. The UV-photolysis was performed either by using a conventional Hg low pressure lamp emitting at 254 nm and also by using a new compact UV-LED source emitting at 360 nm. The kinetics rate constant of silver nanoparticles synthesis produced by γ-radiolysis and UV photolysis were determined and the average diameter of the resulting nanoparticles was estimated. (author)

  7. Molecular structure and spectroscopic characterization of Carbamazepine with experimental techniques and DFT quantum chemical calculations

    Science.gov (United States)

    Suhasini, M.; Sailatha, E.; Gunasekaran, S.; Ramkumaar, G. R.

    2015-04-01

    A systematic vibrational spectroscopic assignment and analysis of Carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation procedure was also performed, and it was used for assigning the 13C and 1H NMR chemical shifts of Carbamazepine.

  8. Molecular diversity of arbuscular mycorrhizal fungi in relation to soil chemical properties and heavy metal contamination

    International Nuclear Information System (INIS)

    Zarei, Mehdi; Hempel, Stefan; Wubet, Tesfaye; Schaefer, Tina; Savaghebi, Gholamreza; Jouzani, Gholamreza Salehi; Nekouei, Mojtaba Khayam; Buscot, Francois

    2010-01-01

    Abundance and diversity of arbuscular mycorrhizal fungi (AMF) associated with dominant plant species were studied along a transect from highly lead (Pb) and zinc (Zn) polluted to non-polluted soil at the Anguran open pit mine in Iran. Using an established primer set for AMF in the internal transcribed spacer (ITS) region of rDNA, nine different AMF sequence types were distinguished after phylogenetic analyses, showing remarkable differences in their distribution patterns along the transect. With decreasing Pb and Zn concentration, the number of AMF sequence types increased, however one sequence type was only found in the highly contaminated area. Multivariate statistical analysis revealed that further factors than HM soil concentration affect the AMF community at contaminated sites. Specifically, the soils' calcium carbonate equivalent and available P proved to be of importance, which illustrates that field studies on AMF distribution should also consider important environmental factors and their possible interactions. - The molecular diversity of AMF was found to be influenced by a combination of soil heavy metal and other soil chemical parameters.

  9. Molecular diversity of arbuscular mycorrhizal fungi in relation to soil chemical properties and heavy metal contamination

    Energy Technology Data Exchange (ETDEWEB)

    Zarei, Mehdi [Department of Soil Science, College of Agriculture, University of Shiraz, Shiraz (Iran, Islamic Republic of); Hempel, Stefan, E-mail: hempel.stefan@googlemail.co [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Soil Ecology, Theodor-Lieser-Strasse 4, 06120 Halle (Germany); Freie Universitaet Berlin, Institut fuer Biologie, Okologie der Pflanzen, Altensteinstrasse 6, 14195 Berlin (Germany); Wubet, Tesfaye; Schaefer, Tina [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Soil Ecology, Theodor-Lieser-Strasse 4, 06120 Halle (Germany); Savaghebi, Gholamreza [Department of Soil Science Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj (Iran, Islamic Republic of); Jouzani, Gholamreza Salehi; Nekouei, Mojtaba Khayam [Agricultural Biotechnology Research Institute of Iran (ABRII), P.O. Box 31535-1897, Karaj (Iran, Islamic Republic of); Buscot, Francois [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Soil Ecology, Theodor-Lieser-Strasse 4, 06120 Halle (Germany)

    2010-08-15

    Abundance and diversity of arbuscular mycorrhizal fungi (AMF) associated with dominant plant species were studied along a transect from highly lead (Pb) and zinc (Zn) polluted to non-polluted soil at the Anguran open pit mine in Iran. Using an established primer set for AMF in the internal transcribed spacer (ITS) region of rDNA, nine different AMF sequence types were distinguished after phylogenetic analyses, showing remarkable differences in their distribution patterns along the transect. With decreasing Pb and Zn concentration, the number of AMF sequence types increased, however one sequence type was only found in the highly contaminated area. Multivariate statistical analysis revealed that further factors than HM soil concentration affect the AMF community at contaminated sites. Specifically, the soils' calcium carbonate equivalent and available P proved to be of importance, which illustrates that field studies on AMF distribution should also consider important environmental factors and their possible interactions. - The molecular diversity of AMF was found to be influenced by a combination of soil heavy metal and other soil chemical parameters.

  10. Chemical and Molecular Descriptors for the Reactivity of Amines with CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Anita S.; Kitchin, John R.

    2012-10-24

    Amine-based solvents are likely to play an important role in CO{sub 2} capture applications in the future, and the identification of amines with superior performance will facilitate their use in CO{sub 2} capture. While some improvements in performance will be achieved through process modifications, modifying the CO{sub 2} capture performance of an amine also implies in part an ability to modify the reactions between the amine and CO{sub 2} through development of new functionalized amines. We present a computational study of trends in the reactions between CO{sub 2} and functionalized amines with a focus on identifying molecular descriptors that determine trends in reactivity. We examine the formation of bicarbonate and carbamate species on three classes of functionalized amines: alkylamines, alkanolamines, and fluorinated alkylamines including primary, secondary and tertiary amines in each class. These functional groups span electron-withdrawing to donating behavior, hydrogen-bonding, extent of functionalization, and proximity effects of the functional groups. Electron withdrawing groups tend to destabilize CO{sub 2} reaction products, whereas electron-donating groups tend to stabilize CO{sub 2} reaction products. Hydrogen bonding stabilizes CO{sub 2} reaction products. Electronic structure descriptors based on electronegativity were found to describe trends in the bicarbonate formation energy. A chemical correlation was observed between the carbamate formation energy and the carbamic acid formation energy. The local softness on the reacting N in the amine was found to partially explain trends carbamic acid formation energy.

  11. Selective antagonists at group I metabotropic glutamate receptors: synthesis and molecular pharmacology of 4-aryl-3-isoxazolol amino acids

    DEFF Research Database (Denmark)

    Kromann, Hasse; Sløk, Frank A; Stensbøl, Tine B

    2002-01-01

    Homologation of (S)-glutamic acid (Glu, 1) and Glu analogues has previously provided ligands with activity at metabotropic Glu receptors (mGluRs). The homologue of ibotenic acid (7), 2-amino-3-(3-hydroxy-5-isoxazolyl)propionic acid (HIBO, 8), and the 4-phenyl derivative of 8, compound 9a, are bot...... antagonists at group I mGluRs. Here we report the synthesis and molecular pharmacology of HIBO analogues 9b-h containing different 4-aryl substituents. All of these compounds possess antagonist activity at group I mGluRs but are inactive at group II and III mGluRs....

  12. Development of a quantum chemical molecular dynamics tribochemical simulator and its application to tribochemical reaction dynamics of lubricant additives

    International Nuclear Information System (INIS)

    Onodera, T; Tsuboi, H; Hatakeyama, N; Endou, A; Miyamoto, A; Miura, R; Takaba, H; Suzuki, A; Kubo, M

    2010-01-01

    Tribology at the atomistic and molecular levels has been theoretically studied by a classical molecular dynamics (MD) method. However, this method inherently cannot simulate the tribochemical reaction dynamics because it does not consider the electrons in nature. Although the first-principles based MD method has recently been used for understanding the chemical reaction dynamics of several molecules in the tribology field, the method cannot simulate the tribochemical reaction dynamics of a large complex system including solid surfaces and interfaces due to its huge computation costs. On the other hand, we have developed a quantum chemical MD tribochemical simulator on the basis of a hybrid tight-binding quantum chemical/classical MD method. In the simulator, the central part of the chemical reaction dynamics is calculated by the tight-binding quantum chemical MD method, and the remaining part is calculated by the classical MD method. Therefore, the developed tribochemical simulator realizes the study on tribochemical reaction dynamics of a large complex system, which cannot be treated by using the conventional classical MD or the first-principles MD methods. In this paper, we review our developed quantum chemical MD tribochemical simulator and its application to the tribochemical reaction dynamics of a few lubricant additives

  13. Systematic methods for synthesis and design of sustainable chemical and biochemical processes

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    Chemical and biochemical process design consists of designing the process that can sustainably manufacture an identified chemical product through a chemical or biochemical route. The chemical product tree is potentially very large; starting from a set of basic raw materials (such as petroleum...... for process intensification, sustainable process design, identification of optimal biorefinery models as well as integrated process-control design, and chemical product design. The lecture will present the main concepts, the decomposition based solution approach, the developed methods and tools together...

  14. Chemical structure, biosynthesis and synthesis of free and glycosylated pyridinolines formed by cross-link of bone and synovium collagen.

    Science.gov (United States)

    Anastasia, Luigi; Rota, Paola; Anastasia, Mario; Allevi, Pietro

    2013-09-21

    This review focuses on the chemical structure, biosynthesis and synthesis of free and glycosylated pyridinolines (Pyds), fluorescent collagen cross-links, with a pyridinium salt structure. Pyds derive from the degradation of bone collagen and have attracted attention for their use as biochemical markers of bone resorption and to assess fracture risk prediction in persons suffering from osteoporosis, bone cancer and other bone or collagen diseases. We consider and critically discuss all reported syntheses of free and glycosylated Pyds evidencing an unrevised chemistry, original and of general utility, analysis of which allows us to also support a previously suggested non-enzymatic formation of Pyds in collagen better rationalizing and justifying the chemical events.

  15. European analytical column No. 36 from the Division of Analytical Chemistry (DAC) of the European Association for Chemical and Molecular Sciences (EuCheMS)

    DEFF Research Database (Denmark)

    Karlberg, Bo; Emons, Hendrik; Andersen, Jens Enevold Thaulov

    2008-01-01

    European analytical column no. 36 from the division of analytical chemistry (DAC) of the European association for chemical and molecular sciences (EuCheMS)......European analytical column no. 36 from the division of analytical chemistry (DAC) of the European association for chemical and molecular sciences (EuCheMS)...

  16. Parametric study of waste chicken fat catalytic chemical vapour deposition for controlled synthesis of vertically aligned carbon nanotubes

    Science.gov (United States)

    Suriani, A. B.; Dalila, A. R.; Mohamed, A.; Rosmi, M. S.; Mamat, M. H.; Malek, M. F.; Ahmad, M. K.; Hashim, N.; Isa, I. M.; Soga, T.; Tanemura, M.

    2016-12-01

    High-quality vertically aligned carbon nanotubes (VACNTs) were synthesised using ferrocene-chicken oil mixture utilising a thermal chemical vapour deposition (TCVD) method. Reaction parameters including vaporisation temperature, catalyst concentration and synthesis time were examined for the first time to investigate their influence on the growth of VACNTs. Analysis via field emission scanning electron microscopy and micro-Raman spectroscopy revealed that the growth rate, diameter and crystallinity of VACNTs depend on the varied synthesis parameters. Vaporisation temperature of 570°C, catalyst concentration of 5.33 wt% and synthesis time of 60 min were considered as optimum parameters for the production of VACNTs from waste chicken fat. These parameters are able to produce VACNTs with small diameters in the range of 15-30 nm and good quality (ID/IG 0.39 and purity 76%) which were comparable to those synthesised using conventional carbon precursor. The low turn on and threshold fields of VACNTs synthesised using optimum parameters indicated that the VACNTs synthesised using waste chicken fat are good candidate for field electron emitter. The result of this study therefore can be used to optimise the growth and production of VACNTs from waste chicken fat in a large scale for field emission application.

  17. Synthesis and characterization of M-type barium hexferrite by ultrasonic inter-dispersion of chemical precipitate

    International Nuclear Information System (INIS)

    Garcia Junior, E.S.; Gomes Junior, G.G.; Ogasawara, T.

    2010-01-01

    This work is concerned with the study the synthesis and characterization of M-type barium hexaferrite powder by chemical precipitation type and ultrasonic interdispersion of precursor materials Fe(OH) 3 and Ba(OH) 2 ,separately and ultrasonic inter-dispersion, followed by drying and calcining. In order to guide the experimental work was carried out a preliminary thermodynamic analysis of the system Ba-Fe-H 2 O at 25 deg C. The study shows that the phase formation of M-type barium hexaferrite is obtained at a calcination at 1000 deg C, characterized by X-ray diffraction, the grain growth of the final product of synthesis depending on the calcination temperature is visible by SEM. The synthesis method developed in this research is an option to achieve the results that would be obtained if the co-precipitation of ferric and barium hydroxide was thermodynamically possible, where you can get crystallization of barium hexaferrite in a calcination at 1000 deg C. (author)

  18. Inhibition of DNA synthesis by chemical carcinogens in cultures of initiated and normal proliferating rat hepatocytes

    International Nuclear Information System (INIS)

    Novicki, D.L.; Rosenberg, M.R.; Michalopoulos, G.

    1985-01-01

    Rat hepatocytes in primary culture can be stimulated to replicate under the influence of rat serum and sparse plating conditions. Higher replication rates are induced by serum from two-thirds partially hepatectomized rats. The effects of carcinogens and noncarcinogens on the ability of hepatocytes to synthesize DNA were examined by measuring the incorporation of [3H]thymidine by liquid scintillation counting and autoradiography. Hepatocyte DNA synthesis was not decreased by ethanol or dimethyl sulfoxide at concentrations less than 0.5%. No effect was observed when 0.1 mM ketamine, Nembutal, hypoxanthine, sucrose, ascorbic acid, or benzo(e)pyrene was added to cultures of replicating hepatocytes. Estrogen, testosterone, tryptophan, and vitamin E inhibited DNA synthesis by approximately 50% at 0.1 mM, a concentration at which toxicity was noticeable. Several carcinogens requiring metabolic activation as well as the direct-acting carcinogen N-methyl-N'-nitro-N-nitrosoguanidine interfered with DNA synthesis. Aflatoxin B1 inhibited DNA synthesis by 50% (ID50) at concentrations between 1 X 10(-8) and 1 X 10(-7) M. The ID50 for 2-acetylaminofluorene was between 1 X 10(-7) and 1 X 10(-6) M. Benzo(a)pyrene and 3'-methyl-4-dimethylaminoazobenzene inhibited DNA synthesis 50% between 1 X 10(-5) and 1 X 10(-4) M. Diethylnitrosamine and dimethylnitrosamine (ID50 between 1 X 10(-4) and 5 X 10(-4) M) and 1- and 2-naphthylamine (ID50 between 1 X 10(-5) and 5 X 10(-4) M) caused inhibition of DNA synthesis at concentrations which overlapped with concentrations that caused measurable toxicity

  19. Influence of the dopant during the one step mechano-chemical synthesis of sodium alanate

    International Nuclear Information System (INIS)

    Rongeat, C; Geipel, C; Llamas-Jansa, I; Schultz, L; Gutfleisch, O

    2009-01-01

    High-pressure reactive milling under hydrogen atmosphere is used for the one-step synthesis of doped sodium alanate. In-situ monitoring of the pressure and the temperature inside the vial gives a direct feedback about the reactions occurring during the milling. This information is used to study the influence of the dopant during synthesis, e.g. the amount of dopant added. The study of the pressure variations during milling is a reliable tool for screening the efficiency of different dopants.

  20. The direct conversion of synthesis gas to chemicals / Ernest du Toit

    OpenAIRE

    Du Toit, Ernest

    2002-01-01

    The catalytic conversion of synthesis gas, obtainable from the processing of coal, biomass or natural gas, to a complex hydrocarbon product stream can be achieved via the Fischer-Tropsch process. The Fischer-Tropsch synthesis process has evolved from being mainly a fuel producing process in the early 1950's to that of a solvent and speciality wax production process towards the end of the 1970's. From the early 1980's there has been a clear shift towards the production of commod...