Newly synthesized benzanthrone derivatives as prospective fluorescent membrane probes

International Nuclear Information System (INIS)

Zhytniakivska, Olga; Trusova, Valeriya; Gorbenko, Galyna; Kirilova, Elena; Kalnina, Inta; Kirilov, Georgiy; Kinnunen, Paavo

2014-01-01

Fluorescence spectral properties of a series of novel benzanthrone derivatives have been explored in lipid bilayers composed of zwitterionic lipid phosphatidylcholine (PC) and its mixtures with cholesterol (Chol) and anionic phospholipid cardiolipin (CL). Analysis of partition coefficients showed that all the examined compounds possess rather high lipid-associating ability, with the amidino derivatives exhibiting stronger membrane partitioning compared with the aminobenzanthrones. To understand how benzanthrone partition properties correlate with their structure, quantitative structure property relationship (QSPR) analysis was performed involving a range of quantum chemical molecular descriptors. -- Highlights: • Benzanthrone partitioning into lipid bilayer correlates with lipophilicity of the dyes. • Partition properties of benzanthrones depend on the dye dipole moment. • Amidino derivatives exhibit higher membrane affinity than aminobenzanthrones

Chemical exchange in novel spirobicyclic zwitterionic Janovsky complexes using dynamic 1H NMR spectroscopy.

Science.gov (United States)

Culf, A S; Cuperlović-Culf, M; Ouellette, R J

2009-02-01

Highly coloured Janovsky complexes have been known for over 120 years, being used in many colourimetric analytical procedures. In this present study, two novel and stable nitrocyclohexadienyl spirobicyclic, zwitterionic Janovsky anionic hydantoin sigma-complexes, rac-1,3-diisopropyl-6-nitro-2,4-dioxo-1,3-diazaspiro[4.5]deca-6,9-dien-8-ylideneazinate, ammonium internal salt (1) and 1,3-diisopropyl-2,4-dioxo-1,3-diazaspiro[4.5]deca-6,9-dien-8-ylideneazinate, ammonium internal salt (2) have been prepared and characterised by NMR, electrospray ionization mass spectrometry (ESI-MS) and UV/visible methods. For the p-mononitro-substituted complex (2), we discovered chemical exchange behaviour using 1D saturation transfer and 2D exchange spectroscopy (EXSY) (1)H NMR techniques. The coalescence temperature was determined to be 62 degrees C in d(3)-acetonitrile. Analysis of these data provided a Gibbs free energy of activation, DeltaG double dagger, of + 67 kJ mole(-1), a rate constant, k, coalescence of 220 Hz and an equilibrium constant, K(eqm), of 0.98 as estimates of the exchange process in this solvent. Of the two mechanisms proposed for this fluxional behaviour, ring opening to a substituted benzene or proton exchange, a further theoretical modelling study of 1D (1)H NMR spectra was able to confirm that simple proton exchange between the two nitrogen sites of the hydantoin ring provided an accurate simulation of the observed experimental evidence. Interestingly, the o,p-dinitro-substituted complex (1) did not show any chemical exchange behaviour up to 150 degrees C in d(3)-acetonitrile (to 75 degrees C) and d(6)-dimethyl sulfoxide (DMSO). Molecular modelling at the MM2 level suggests that steric collisions of an N-acyl isopropyl substituent of the hydantoin ring with the ortho-nitro group of the spirofused cyclohexadienyl ring prevents the proposed proton exchange mechanism occurring in this case. 2008 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

Efficient Preparation of Super Antifouling PVDF Ultrafiltration Membrane with One Step Fabricated Zwitterionic Surface.

Science.gov (United States)

Zhao, Xinzhen; He, Chunju

2015-08-19

On the basis of the excellent fouling resistance of zwitterionic materials, the super antifouling polyvinylidene fluoride (PVDF) membrane was efficiently prepared though one-step sulfonation of PVDF and polyaniline blend membrane in situ. The self-doped sulfonated polyaniline (SPANI) was generated as a novel zwitterionic polymer to improve the antifouling property of PVDF ultrafiltration membrane used in sewage treatment. Surface attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface zeta potential, and water contact angle demonstrated the successful fabrication of zwitterionic interface by convenient sulfonation modification. The static adsorption fouling test showed the quantified adsorption mass of bovine serum albumin (BSA) pollutant on the PVDF/SPANI membrane surface decreases to 3(±2) μg/cm(2), and the water flux recovery ratio (FRR) values were no less than 95% for the three model pollutants of BSA, sodium alginate (SA), and humic acid (HA), which were corresponding hydrophobic, hydrophilic, and natural pollutants in sewage, respectively. This Research Article demonstrated the antifouling advantages of zwitterionic SPANI and aimed to provide a simple method for the large scale preparation of zwitterionic antifouling ultrafiltration membranes.

Zwitterionic states in gas-phase polypeptide ions revealed by 157-nm ultra-violet photodissociation

DEFF Research Database (Denmark)

Kjeldsen, Frank; Silivra, Oleg A; Zubarev, Roman A

2006-01-01

carboxylic groups relative to competing COOH losses (45 Da) from neutral carboxylic groups. Loss of CO2 is a strong indication of the presence of a zwitterionic [(+)...(-)...(+)] salt bridge in the gas-phase polypeptide cation. This method provides a tool for studying, for example, the nature of binding...... of the fragment formation should be taken into account. Cations of Trp-cage proteins exist preferentially as zwitterions, with the deprotonation position divided between the Asp9 residue and the C terminus in the ratio 3:2. The majority of dications of the same molecule are not zwitterions. Furthermore, 157-nm...

Catalytic copolymerization of CO and ethylene with a charge neutral palladium(II) zwitterion.

Science.gov (United States)

Lu, Connie C; Peters, Jonas C

2002-05-15

The synthesis of a zwitterionic Pd(II) complex supported by an anionic bis(phosphino)borate ligand, Ph(2)B(CH(2)PPh(2))(2) (abbreviated as [Ph(2)BP(2)]), is reported. The new complex, [Ph(2)BP(2)]PdMe(THF), is active for CO and ethylene copolymerization. The copolymerization activity and polyketone molecular weight for the neutral, zwitterionic system are compared with those for the cationic systems [R(2)E(CH(2)PPh(2))(2)PdMe(THF)][B(C(6)F(5))(4)] where ER(2) = SiPh(2) and CH(2). Surprisingly, the more electron rich zwitterionic system is a catalyst of activity comparable to that of the more conventional cationic systems.

13C and 15N CP/MAS, 1H-15N SCT CP/MAS and FTIR spectroscopy as tools for qualitative detection of the presence of zwitterionic and non-ionic forms of ansa-macrolide 3-formylrifamycin SV and its derivatives in solid state.

Science.gov (United States)

Przybylski, Piotr; Pyta, Krystian; Klich, Katarzyna; Schilf, Wojciech; Kamieński, Bohdan

2014-01-01

(13)C, (15)N CP/MAS, including (1)H-(13)C and (1)H-(15)N short contact time CP/MAS experiments, and FTIR methods were applied for detailed structural characterization of ansa-macrolides as 3-formylrifamycin SV (1) and its derivatives (2-6) in crystal and in powder forms. Although HPLC chromatograms for 2/CH3 OH and 2/CH3 CCl3 were the same for rifampicin crystals dissolved in respective solvents, the UV-vis data recorded for them were different in 300-375 nm region. Detailed solid state (13)C and (15)N CP/MAS NMR and FTIR studies revealed that rifampicin (2), in contrast to 3-formylrifamycin SV (1) and its amino derivatives (3-6), can occur in pure non-ionic or zwitterionic forms in crystal and in pure these forms or a mixture of them in a powder. Multinuclear CP/MAS and FTIR studies demonstrated also that 3-6 derivatives were present exclusively in pure zwitterionic forms, both in powder and in crystal. On the basis of the solid state NMR and FTIR studies, two conformers of 3-formylrifamycin SV were detected in powder form due to the different orientations of carbonyl group of amide moiety. The PM6 molecular modeling at the semi-empirical level of theory, allowed visualization the most energetically favorable non-ionic and zwitterionic forms of 1-6 antibiotics, strongly stabilized via intramolecular H-bonds. FTIR studies indicated that the originally adopted forms of these type antibiotics in crystal or in powder are stable in standard laboratory conditions in time. The results presented point to the fact that because of a possible presence of two forms of rifampicin (compound 2), quantification of the content of this antibiotic in relevant pharmaceuticals needs caution. Copyright © 2013 John Wiley & Sons, Ltd.

Zwitterionic sulfobetaine-grafted poly(vinylidene fluoride) membrane with highly effective blood compatibility via atmospheric plasma-induced surface copolymerization.

Science.gov (United States)

Chang, Yung; Chang, Wan-Ju; Shih, Yu-Ju; Wei, Ta-Chin; Hsiue, Ging-Ho

2011-04-01

Development of nonfouling membranes to prevent nonspecific protein adsorption and platelet adhesion is critical for many biomedical applications. It is always a challenge to control the surface graft copolymerization of a highly polar monomer from the highly hydrophobic surface of a fluoropolymer membrane. In this work, the blood compatibility of poly(vinylidene fluoride) (PVDF) membranes with surface-grafted electrically neutral zwitterionic poly(sulfobetaine methacrylate) (PSBMA), from atmospheric plasma-induced surface copolymerization, was studied. The effect of surface composition and graft morphology, electrical neutrality, hydrophilicity and hydration capability on blood compatibility of the membranes were determined. Blood compatibility of the zwitterionic PVDF membranes was systematically evaluated by plasma protein adsorption, platelet adhesion, plasma-clotting time, and blood cell hemolysis. It was found that the nonfouling nature and hydration capability of grafted PSBMA polymers can be effectively controlled by regulating the grafting coverage and charge balance of the PSBMA layer on the PVDF membrane surface. Even a slight charge bias in the grafted zwitterionic PSBMA layer can induce electrostatic interactions between proteins and the membrane surfaces, leading to surface protein adsorption, platelet activation, plasma clotting and blood cell hemolysis. Thus, the optimized PSBMA surface graft layer in overall charge neutrality has a high hydration capability and the best antifouling, anticoagulant, and antihemolytic activities when comes into contact with human blood. © 2011 American Chemical Society

Design and preparation of bi-functionalized short-chain modified zwitterionic nanoparticles.

Science.gov (United States)

Hu, Fenglin; Chen, Kaimin; Xu, Hong; Gu, Hongchen

2018-05-01

An ideal nanomaterial for use in the bio-medical field should have a distinctive surface capable of effectively preventing nonspecific protein adsorption and identifying target bio-molecules. Recently, the short-chain zwitterion strategy has been suggested as a simple and novel approach to create outstanding anti-fouling surfaces. In this paper, the carboxyl end group of short-chain zwitterion-coated silica nanoparticles (SiO 2 -ZWS) was found to be difficult to functionalize via a conventional EDC/NHS strategy due to its rapid hydrolysis side-reactions. Hence, a series of bi-functionalized silica nanoparticles (SiO 2 -ZWS/COOH) were designed and prepared by controlling the molar ratio of 3-aminopropyltriethoxysilane (APTES) to short-chain zwitterionic organosiloxane (ZWS) in order to achieve above goal. The synthesized SiO 2 -ZWS/COOH had similar excellent anti-fouling properties compared with SiO 2 -ZWS, even in 50% fetal bovine serum characterized by DLS and turbidimetric titration. Subsequently, SiO 2 -ZWS/COOH 5/1 was chosen as a representative and then demonstrated higher detection signal intensity and more superior signal-to-noise ratios compare with the pure SiO 2 -COOH when they were used as a bio-carrier for chemiluminescence enzyme immunoassay (CLEIA). These unique bi-functionalized silica nanoparticles have many potential applications in the diagnostic and therapeutic fields. Reducing nonspecific protein adsorption and enhancing the immobilized efficiency of specific bio-probes are two of the most important issues for bio-carriers, particularly for a nanoparticle based bio-carrier. Herein, we designed and prepared a bi-functional nanoparticle with anti-fouling property and bio conjugation capacity for further bioassay by improving the short-chain zwitterionic modification strategy we have proposed previously. The heterogeneous surface of this nanoparticle showed effective anti-fouling properties both in model protein solutions and fetal bovine serum

Swelling dynamics of zwitterionic copolymers: The effects of concentration and type of anion and cation

NARCIS (Netherlands)

de Grooth, Joris; Ogieglo, Wojciech; de Vos, Wiebe Matthijs; Girones nogue, Miriam; Nijmeijer, Dorothea C.; Benes, Nieck Edwin

2014-01-01

The effect of different salts and their concentration on the swelling of zwitterionic copolymers has been investigated for bulk polymer samples as well as for thin films. Relatively low ratios of the zwitterionic monomer already radically change the swelling properties of the copolymer. Increasing

Gas sorption properties of zwitterion-functionalized carbon nanotubes

Czech Academy of Sciences Publication Activity Database

Surapathi, A.; Chen, H.-Y.; Marand, E.; Johnson, J. K.; Sedláková, Zdeňka

2013-01-01

Roč. 429, 15 February (2013), s. 88-94 ISSN 0376-7388 R&D Projects: GA MŠk ME09058 Institutional support: RVO:61389013 Keywords : carbon nanotube * zwitterion functionalized membrane * adsorption of gas es Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.908, year: 2013

hERG blocking potential of acids and zwitterions characterized by three thresholds for acidity, size and reactivity

DEFF Research Database (Denmark)

Nikolov, Nikolai Georgiev; Dybdahl, Marianne; Jonsdottir, Svava Osk

2014-01-01

with a concordance of 91% by a decision tree based on the rule. Two external validations were performed with sets of 35 and 48 observations, respectively, both showing concordances of 91%. In addition, a global QSAR model of hERG blocking was constructed based on a large diverse training set of 1374 chemicals...... covering all ionization classes, externally validated showing high predictivity and compared to the decision tree. The decision tree was found to be superior for the acids and zwitterionic ampholytes classes....

New chiral zwitterionic phosphorus heterocycles: synthesis, structure, properties and application as chiral solvating agents.

Science.gov (United States)

Sheshenev, Andrey E; Boltukhina, Ekaterina V; Grishina, Anastasiya A; Cisařova, Ivana; Lyapkalo, Ilya M; Hii, King Kuok Mimi

2013-06-17

A family of new chiral zwitterionic phosphorus-containing heterocycles (zPHC) have been derived from methylene-bridged bis(imidazolines). These structures were unambiguously determined, including single-crystal XRD analysis for two compounds. The stability, acid/base and electronic properties of these dipolar phosphorus heterocycles were subsequently investigated. zPHCs can be successfully employed as a new class of chiral solvating agents for the enantiodifferentiation of chiral carboxylic and sulfonic acids by NMR spectroscopy. The stoichiometry and binding constants for the donor-acceptor complexes formed were established by NMR titration methods. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unfolding a molecular trefoil derived from a zwitterionic metallopeptide to form self-assembled nanostructures

KAUST Repository

Zhang, Ye; Zhou, Ning; Shi, Junfeng; Pochapsky, Susan Sondej; Pochapsky, Thomas C.; Zhang, Bei; Zhang, Xixiang; Xu, Bing

2015-01-01

While used extensively by nature to control the geometry of protein structures, and dynamics of proteins, such as self-organization, hydration forces and ionic interactions received less attention for controlling the behaviour of small molecules. Here we describe the synthesis and characterization of a novel zwitterionic metallopeptide consisting of a cationic core and three distal anionic groups linked by self-assembling peptide motifs. 2D NMR spectra, total correlated spectroscopy and nuclear Overhauser effect spectroscopy, show that the molecule exhibits a three-fold rotational symmetry and adopts a folded conformation in dimethyl sulfoxide due to Coulombic forces. When hydrated in water, the molecule unfolds to act as a self-assembling building block of supramolecular nanostructures. By combining ionic interactions with the unique geometry from metal complex and hydrophobic interactions from simple peptides, we demonstrate a new and effective way to design molecules for smart materials through mimicking a sophisticated biofunctional system using a conformational switch.

Unfolding a molecular trefoil derived from a zwitterionic metallopeptide to form self-assembled nanostructures

KAUST Repository

Zhang, Ye

2015-02-19

While used extensively by nature to control the geometry of protein structures, and dynamics of proteins, such as self-organization, hydration forces and ionic interactions received less attention for controlling the behaviour of small molecules. Here we describe the synthesis and characterization of a novel zwitterionic metallopeptide consisting of a cationic core and three distal anionic groups linked by self-assembling peptide motifs. 2D NMR spectra, total correlated spectroscopy and nuclear Overhauser effect spectroscopy, show that the molecule exhibits a three-fold rotational symmetry and adopts a folded conformation in dimethyl sulfoxide due to Coulombic forces. When hydrated in water, the molecule unfolds to act as a self-assembling building block of supramolecular nanostructures. By combining ionic interactions with the unique geometry from metal complex and hydrophobic interactions from simple peptides, we demonstrate a new and effective way to design molecules for smart materials through mimicking a sophisticated biofunctional system using a conformational switch.

The pH behavior of a 2-aminoethyl dihydrogen phosphate zwitterion studied with NMR-titrations

Science.gov (United States)

Myller, A. T.; Karhe, J. J.; Haukka, M.; Pakkanen, T. T.

2013-02-01

In this study a bifunctional 2-aminoethyl dihydrogen phosphate (AEPH2) was 1H and 31P NMR characterized in a pH range of 1-12 in order to determine the zwitterion properties in different pH regions in H2O and D2O solutions. NMR was also used to determine the pH range where AEPH2 exists as a zwitterion. The phosphate group has two deprotonation points, around pH 1 and 6, while the amino group deprotonates at pH 11. The zwitterion form of AEPH2 (NH3+sbnd CHsbnd CHsbnd OPOH) exists as the main ion between pH 1 and 6 in water solutions and also in the solid state.

Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

Science.gov (United States)

Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

Superior Antifouling Performance of a Zwitterionic Peptide Compared to an Amphiphilic, Non-Ionic Peptide.

Science.gov (United States)

Ye, Huijun; Wang, Libing; Huang, Renliang; Su, Rongxin; Liu, Boshi; Qi, Wei; He, Zhimin

2015-10-14

The aim of this study was to explore the influence of amphiphilic and zwitterionic structures on the resistance of protein adsorption to peptide self-assembled monolayers (SAMs) and gain insight into the associated antifouling mechanism. Two kinds of cysteine-terminated heptapeptides were studied. One peptide had alternating hydrophobic and hydrophilic residues with an amphiphilic sequence of CYSYSYS. The other peptide (CRERERE) was zwitterionic. Both peptides were covalently attached onto gold substrates via gold-thiol bond formation. Surface plasmon resonance analysis results showed that both peptide SAMs had ultralow or low protein adsorption amounts of 1.97-11.78 ng/cm2 in the presence of single proteins. The zwitterionic peptide showed relatively higher antifouling ability with single proteins and natural complex protein media. We performed molecular dynamics simulations to understand their respective antifouling behaviors. The results indicated that strong surface hydration of peptide SAMs contributes to fouling resistance by impeding interactions with proteins. Compared to the CYSYSYS peptide, more water molecules were predicted to form hydrogen-bonding interactions with the zwitterionic CRERERE peptide, which is in agreement with the antifouling test results. These findings reveal a clear relation between peptide structures and resistance to protein adsorption, facilitating the development of novel peptide-containing antifouling materials.

Approaching an organic semimetal: Electron pockets at the Fermi level for a p-benzoquinonemonoimine zwitterion

Energy Technology Data Exchange (ETDEWEB)

Rosa, Luis G.; Velev, Julian [Department of Physics and Electronics, University of Puerto Rico, Humacao (United States); Institute for Functional Nanomaterials, University of Puerto Rico, San Juan (United States); Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, NE (United States); Zhang, Zhengzheng [Department of Physics, University of Puerto Rico, Rio Piedras, San Juan (United States); Alvira, Jose; Vega, Omar; Diaz, Gerson [Department of Physics and Electronics, University of Puerto Rico, Humacao (United States); Routaboul, Lucie; Braunstein, Pierre [Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Universite de Strasbourg (France); Doudin, Bernard [Institut de Physique, Applique de Physique et Chimie des Materiaux de Strasbourg, Universite Louis Pasteur Strasbourg (France); Losovyj, Yaroslav B. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan (United States); J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State Univ., Baton Rouge, LA (United States); Dowben, Peter A. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan (United States)

2012-08-15

There is compelling evidence of electron pockets, at the Fermi level, in the band structure for an organic zwitterion molecule of the p-benzoquinonemonoimine type. The electronic structure of the zwitterion molecular film has a definite, although small, density of states evident at the Fermi level as well as a nonzero inner potential and thus is very different from a true insulator. In spite of a small Brillouin zone, significant band width is observed in the intermolecular band dispersion. The results demonstrate that Bloch's theorem applies to the wave vector dependence of the electronic band structure formed from the molecular orbitals of adjacent molecules in a molecular thin film of a p-benzoquinonemonoimine type zwitterion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Preparation and characterization of novel zwitterionic poly(arylene ether sulfone) ultrafiltration membrane with good thermostability and excellent antifouling properties

Science.gov (United States)

Rong, Guolong; Zhou, Di; Han, Xiaocui; Pang, Jinhui

2018-01-01

Zwitterionic poly(arylene ether sulfone) (PAES-NS) was synthesized via copolymerization by using a bisphenol monomer with a pyridine group. The chemical structures of the copolymers were confirmed by using Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopy; the copolymers showed good thermal stability. A series of polyphenysulfone (PPSU)/PAES-NS blend ultrafiltration (UF) membranes was prepared via conventional immersion precipitation phase inversion methods The morphologies of the modified membranes were investigated by scanning electron microscopy (SEM). The surface hydrophilicity of the UF membranes was studied by water contact angle measurement, indicating that the zwitterionic group increased the membrane hydrophilicity. UF of solvated model pollutants using the membranes showed a significant reduction of the irreversible adsorption of the foulants, illustrating the excellent anti-fouling properties of the membrane. The water flux of the PAES-NS membrane was significantly enhanced, being almost three times higher than that of the pristine PPSU membrane, with retention of a high rejection level. After three UF cycles, the water flux recovery of the PAES-NS membrane was as high as 96%.

Selective Interaction of a Cationic Polyfluorene with Model Lipid Membranes: Anionic versus Zwitterionic Lipids

Directory of Open Access Journals (Sweden)

Zehra Kahveci

2014-03-01

Full Text Available This paper explores the interaction mechanism between the conjugated polyelectrolyte {[9,9-bis(6'-N,N,N-trimethylammoniumhexyl]fluorene-phenylene}bromide (HTMA-PFP and model lipid membranes. The study was carried out using different biophysical techniques, mainly fluorescence spectroscopy and microscopy. Results show that despite the preferential interaction of HTMA-PFP with anionic lipids, HTMA-PFP shows affinity for zwitterionic lipids; although the interaction mechanism is different as well as HTMA-PFP’s final membrane location. Whilst the polyelectrolyte is embedded within the lipid bilayer in the anionic membrane, it remains close to the surface, forming aggregates that are sensitive to the physical state of the lipid bilayer in the zwitterionic system. The different interaction mechanism is reflected in the polyelectrolyte fluorescence spectrum, since the maximum shifts to longer wavelengths in the zwitterionic system. The intrinsic fluorescence of HTMA-PFP was used to visualize the interaction between polymer and vesicles via fluorescence microscopy, thanks to its high quantum yield and photostability. This technique allows the selectivity of the polyelectrolyte and higher affinity for anionic membranes to be observed. The results confirmed the appropriateness of using HTMA-PFP as a membrane fluorescent marker and suggest that, given its different behaviour towards anionic and zwitterionic membranes, HTMA-PFP could be used for selective recognition and imaging of bacteria over mammalian cells.

Rapid, facile synthesis of conjugated polymer zwitterions in ionic liquids

Energy Technology Data Exchange (ETDEWEB)

Page, Zachariah A. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Liu, Feng [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Russell, Thomas P. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Emrick, Todd [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA

2014-01-01

Ionic liquids (ILs) were utilized for the rapid air-stable Suzuki polymerization of polar zwitterionic thiophene monomers, precluding the need for volatile organic solvents, phosphine ligands and phase transfer catalysts typically used in conjugated polymer synthesis.

Controllable Self-Assembly of Amphiphilic Zwitterionic PBI Towards Tunable Surface Wettability of the Nanostructures.

Science.gov (United States)

Ye, Yong; Lü, Baozhong; Cheng, Wenyu; Wu, Zhen; Wei, Jie; Yin, Meizhen

2017-05-04

Amphiphilic molecules have received wide attention as they possess both hydrophobic and hydrophilic properties, and can form diverse nanostructures in selective solvents. Herein, we report an asymmetric amphiphilic zwitterionic perylene bisimide (AZP) with an octyl chain and a zwitterionic group on the opposite imide positions of perylene tetracarboxylic dianhydride. The controllable nanostructures of AZP with tunable hydrophilic/hydrophobic surface have been investigated through solvent-dependent amphiphilic self-assembly as confirmed by SEM, TEM, and contact angle measurements. The planar perylene core of AZP contributes to strong π-π stacking, while the amphiphilic balance of asymmetric AZP adjusts the self-assembly property. Additionally, due to intermolecular π-π stacking and solvent-solute interactions, AZP could self-assemble into hydrophilic microtubes in a polar solvent (acetone) and hydrophobic nanofibers in an apolar solvent (hexane). This facile method provides a new pathway for controlling the surface properties based on an asymmetric amphiphilic zwitterionic perylene bisimide. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of zwitterionic salts of pyridinium-Meldrum acid and barbiturate through unique four-component reactions.

Science.gov (United States)

Wang, Qi-Fang; Hui, Li; Hou, Hong; Yan, Chao-Guo

2010-03-08

An efficient synthetic procedure for the preparation of the unusual charge-separated pyridinium-Meldrum acid and N,N-dimethylbarbiturate acid zwitterionic salts was developed though a unique one-pot four-component reaction involving pyridine, aromatic aldehyde, Meldrum acid or N,N-dimethylbarbituric acid, and p-nitrobenzyl bromide in acetonitrile. By varying combinations of four components involving nitrogen-containing heterocycles, we conveniently established reactive alpha-halomethylene compounds, aldehydes and beta-dicarbonyl compounds a library of zwitterionic salts.

Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

NARCIS (Netherlands)

Nguyen, A.T.; Baggerman, J.; Paulusse, J.M.J.; Rijn, van C.J.M.; Zuilhof, H.

2011-01-01

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable

Bottom-up fabrication of zwitterionic polymer brushes on intraocular lens for improved biocompatibility

Directory of Open Access Journals (Sweden)

Han Y

2016-12-01

Full Text Available Yuemei Han,1,* Xu Xu,1,* Junmei Tang,1,* Chenghui Shen,2 Quankui Lin,1,2 Hao Chen1,2 1School of Ophthalmology & Optometry, Eye Hospital, Wenzhou Medical University, 2Wenzhou Institute of Biomaterials and Engineering, Chinese Academy of Sciences, Wenzhou, People’s Republic of China *These authors contributed equally to this work Abstract: Intraocular lens (IOL is an efficient implantable device commonly used for treating cataracts. However, bioadhesion of bacteria or residual lens epithelial cells on the IOL surface after surgery causes postoperative complications, such as endophthalmitis or posterior capsular opacification, and leads to loss of sight again. In the present study, zwitterionic polymer brushes were fabricated on the IOL surface via bottom-up grafting procedure. The attenuated total reflection-Fourier transform infrared and contact angle measurements indicated successful surface modification, as well as excellent hydrophilicity. The coating of hydrophilic zwitterionic polymer effectively decreased the bioadhesion of lens epithelial cells or bacteria. In vivo intraocular implantation results showed good in vivo biocompatibility of zwitterionic IOL and its effectiveness against postoperative complications. Keywords: RAFT, surface modification, endophthalmitis, PCO, in vivo

Mixed-mode chromatography with zwitterionic phosphopeptidomimetic selectors from Ugi multicomponent reaction

NARCIS (Netherlands)

Gargano, Andrea F G; Leek, Tomas; Lindner, Wolfgang; Lämmerhofer, Michael

2013-01-01

In the present contribution a novel Ugi multicomponent reaction (MCR) was used to generate zwitterionic chromatographic selectors with capability for application in mixed-mode chromatography featuring complementary selectivities in reversed-phase (RP) and hydrophilic interaction liquid

Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

NARCIS (Netherlands)

Nguyen, Ai T.; Baggerman, Jacob; Paulusse, Jos Marie Johannes; van Rijn, Cees J.M.; Zuilhof, Han

2011-01-01

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable Si−C

Hydrogen-bonded co-crystal structure of benzoic acid and zwitterionic l-proline

Directory of Open Access Journals (Sweden)

Aaron M. Chesna

2017-03-01

Full Text Available The title compound [systematic name: benzoic acid–pyrrolidin-1-ium-2-carboxylate (1/1], C7H6O2·C5H9NO2, is an example of the application of non-centrosymmetric co-crystallization for the growth of a crystal containing a typically centrosymmetric component in a chiral space group. It co-crystallizes in the space group P212121 and contains benzoic acid and l-proline in equal proportions. The crystal structure exhibits chains of l-proline zwitterions capped by benzoic acid molecules which form a C(5[R33(11] hydrogen-bonded network along [100]. The crystal structure is examined and compared to that of a similar co-crystal containing l-proline zwitterions and 4-aminobenzoic acid.

Amino Acid Functionalization of Doped Single-Walled Carbon Nanotubes: Effects of Dopants and Side Chains as Well as Zwitterionic Stabilizations.

Science.gov (United States)

Jiang, Lisha; Zhu, Chang; Fu, Yujie; Yang, Gang

2017-04-06

Functionalization of single-walled carbon nanotubes (SWCNTs) is necessitated in a number of conditions such as drug delivery, and here amino acid functionalization of SWCNTs is conducted within the framework of density functional theory. Functionalization efficiencies of Gly are largely determined by dopants, as a combined effect of atomic radius, electronic configuration, and distortion to SWCNTs. Different functionalization sites in Gly have divergent interaction strengths with M/SWCNTs that decline as O b > N > O a , and this trend seems almost independent of the identity of metallic dopants. B/SWCNT behaves distinctly and prefers to the N site. Dopants affect principally interaction strengths, while amino acids regulate significantly both functionalization configurations and interaction energies. Then focus is given to stabilization of zwitterionic amino acids due to enhanced interactions with the widely used zwitterionic drugs. All metallic dopants render zwitterionic Gly to be the most stable, and side chains in amino acids rather than dopants in M/SWCNTs cause more pronounced effects to zwitterionic stabilizations. Charge transfers between amino acids and M/SWCNTs are closely associated with zwitterionic stabilization effects, and different charge transfer mechanisms between M/SWCNTs and metal ions are interpreted. Thus, this work provides a comprehensive understanding of amino acid functionalization of M/SWCNTs.

Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

Energy Technology Data Exchange (ETDEWEB)

Malek, Ali; Balawender, Robert, E-mail: rbalawender@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw (Poland)

2015-02-07

The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

International Nuclear Information System (INIS)

Malek, Ali; Balawender, Robert

2015-01-01

The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor

Direct coupling of electromembrane extraction to mass spectrometry - Advancing the probe functionality toward measurements of zwitterionic drug metabolites.

Science.gov (United States)

Rye, Torstein Kige; Fuchs, David; Pedersen-Bjergaard, Stig; Petersen, Nickolaj Jacob

2017-08-29

A triple-flow electromembrane extraction (EME) probe was developed and coupled directly to electrospray-ionization mass spectrometry (ESI-MS). Metabolic reaction mixtures (pH 7.4) containing drug substances and related metabolites were continuously drawn (20 μL/min) into the EME probe in one flow channel, and mixed inside the probe with 7.5 μL min -1 of 1 M formic acid as make-up flow from a second flow channel. Following this acidification, the drug substances and their related metabolites were continuously extracted by EME at 400 V, across a supported liquid membrane (SLM) comprising 2-nitrophenyl octyl ether (and for some experiments containing 30% triphenyl phosphate (TPP)), and into 20 μL min -1 of formic acid as acceptor phase, which was introduced through a third flow channel. The acceptor phase was pumped directly to the MS system, and the ion intensity of extracted analytes was followed continuously as function of time. The triple-flow EME probe was used for co-extraction of positively charged parent drugs and their zwitterionic drug metabolites (hydroxyzine and its carboxylic acid metabolite cetirizine; and vortioxetine and its carboxylic acid metabolite Lu AA34443). While the zwitterionic metabolites could not be extracted at pH 7.4, it was shown that by acidifying the sample solution the zwitterionic metabolites could be extracted effectively. Various extraction parameters like make-up flow, extraction voltage and SLM composition were optimized for simultaneous extraction of parent drugs and metabolites. It was found that TPP added to the SLM improved extraction efficiencies of certain drug metabolites. Finally the optimized and characterized triple-flow EME probe was used for online studying the in-vitro metabolism of hydroxyzine and vortioxetine by rat liver microsomes. Due to the automated pre-extraction acidification of the rat liver microsomal solutions, it was possible to continuously monitor formation of the zwitterionic drug

Generic Top-Functionalization of Patterned Antifouling Zwitterionic Polymers on Indium Tin Oxide

NARCIS (Netherlands)

Li, Y.; Giesbers, M.; Zuilhof, H.

2012-01-01

This paper presents a novel surface engineering approach that combines photochemical grafting and surface-initiated atom transfer radical polymerization (SI-ATRP) to attach zwitterionic polymer brushes onto indium tin oxide (ITO) substrates. The photochemically grafted hydroxyl-terminated organic

Highly Selective Enrichment of Glycopeptides Based on Zwitterionically Functionalized Soluble Nanopolymers

Science.gov (United States)

Cao, Weiqian; Huang, Jiangming; Jiang, Biyun; Gao, Xing; Yang, Pengyuan

2016-07-01

Efficient glycopeptides enrichment prior to mass spectrometry analysis is essential for glycoproteome study. ZIC-HILIC (zwitterionic hydrophilic interaction liquid chromatography) based glycopeptides enrichment approaches have been attracting more attention for several benefits like easy operating, high enrichment specificity and intact glycopeptide retained. In this study, Poly (amidoamine) dendrimer (PAMAM) was adopted for the synthesis of zwitterionically functionalized (ZICF) materials for glycopeptide enrichment. The multiple branched structure and good solubility of ZICF-PAMAM enables a sufficient interaction with glycopeptides. The ZICF-PAMAM combined with the FASP-mode enrichment strategy exhibits more superior performance compared with the existing methods. It has the minimum detectable concentration of femtomolar level and high recovery rate of over 90.01%, and can efficiently enrich glycopeptides from complex biological samples even for merely 0.1 μL human serum. The remarkable glycopeptides enrichment capacity of ZICF-PAMAM highlights the potential application in in-depth glycoproteome research, which may open up new opportunities for the development of glycoproteomics.

Spin coherence transfer in chemical transformations monitoredNMR

Energy Technology Data Exchange (ETDEWEB)

Anwar, Sabieh M.; Hilty, Christian; Chu, Chester; Bouchard,Louis-S.; Pierce, Kimberly L.; Pines, Alexander

2006-07-31

We demonstrate the use of micro-scale nuclear magneticresonance (NMR) for studying the transfer of spin coherence innon-equilibrium chemical processes, using spatially separated NMRencoding and detection coils. As an example, we provide the map ofchemical shift correlations for the amino acid alanine as it transitionsfrom the zwitterionic to the anionic form. Our method is unique in thesense that it allows us to track the chemical migration of encodednuclear spins during the course of chemical transformations.

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

International Nuclear Information System (INIS)

Liu, Pingsheng; Chen, Qiang; Yuan, Bo; Chen, Mengzhou; Wu, Shishan; Lin, Sicong; Shen, Jian

2013-01-01

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics. Highlights: • Facile surface modification of silicone rubber with functional brushes • Modified SR surfaces have improved resistance to nonspecific protein adsorption. • Modified SR surfaces have excellent resistance to platelet adhesion. • Zwitteironic surface significant improvement in blood compatibility • Could inspire many creative uses of SR based materials for biomedical

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

Energy Technology Data Exchange (ETDEWEB)

Liu, Pingsheng [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen, Qiang, E-mail: chem100@nju.edu.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); High Technology Research Institute of Nanjing University, Changzhou 213164 (China); Yuan, Bo; Chen, Mengzhou; Wu, Shishan; Lin, Sicong [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Shen, Jian, E-mail: shenj1957@yahoo.com.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

2013-10-15

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics. Highlights: • Facile surface modification of silicone rubber with functional brushes • Modified SR surfaces have improved resistance to nonspecific protein adsorption. • Modified SR surfaces have excellent resistance to platelet adhesion. • Zwitteironic surface significant improvement in blood compatibility • Could inspire many creative uses of SR based materials for biomedical.

The relative abundance of dimethylsulfoniopropionate (DMSP) among other zwitterions in branching coral at Heron Island, southern Great Barrier Reef.

Science.gov (United States)

Swan, Hilton B; Deschaseaux, Elisabeth S M; Jones, Graham B; Eyre, Bradley D

2017-07-01

Dimethylsulfoniopropionate (DMSP) and eleven other target zwitterions were quantified in the branch tips of six Acropora species and Stylophora pistillata hard coral growing on the reef flat surrounding Heron Island in the southern Great Barrier Reef (GBR), Australia. Hydrophilic interaction liquid chromatography mass spectrometry (HILIC-MS) was used for sample analysis with isotope dilution MS applied to quantify DMSP. The concentration of DMSP was ten times greater in A. aspera than A. valida, with this difference being maintained throughout the spring, summer and winter seasons. In contrast, glycine betaine was present in significantly higher concentrations in these species during the summer than the winter. Exposure of branch tips of A. aspera to air and hypo-saline seawater for up to 1 h did not alter the concentrations of DMSP present in the coral when compared with control samples. DMSP was the most abundant target zwitterion in the six Acropora species examined, ranging from 44-78% of all target zwitterions in A. millepora and A. aspera, respectively. In contrast, DMSP only accounted for 7% in S. pistillata, with glycine betaine and stachydrine collectively accounting for 88% of all target zwitterions in this species. The abundance of DMSP in the six Acropora species examined points to Acropora coral being an important source for the biogeochemical cycling of sulfur throughout the GBR, since this reef-building branching coral dominates the coral cover of the GBR. Graphical Abstract HILIC-MS extracted ion chromatogram showing zwitterionic metabolites from the branching coral Acropora isopora.

Chemical Sensors Based on Cyclodextrin Derivatives.

Science.gov (United States)

Ogoshi, Tomoki; Harada, Akira

2008-08-25

This review focuses on chemical sensors based on cyclodextrin (CD) derivatives. This has been a field of classical interest, and is now of current interest for numerous scientists. First, typical chemical sensors using chromophore appended CDs are mentioned. Various "turn-off" and "turn-on" fluorescent chemical sensors, in which fluorescence intensity was decreased or increased by complexation with guest molecules, respectively, were synthesized. Dye modified CDs and photoactive metal ion-ligand complex appended CDs, metallocyclodextrins, were also applied for chemical sensors. Furthermore, recent novel approaches to chemical sensing systems using supramolecular structures such as CD dimers, trimers and cooperative binding systems of CDs with the other macrocycle [2]rotaxane and supramolecular polymers consisting of CD units are mentioned. New chemical sensors using hybrids of CDs with p-conjugated polymers, peptides, DNA, nanocarbons and nanoparticles are also described in this review.

Synthesis and characterization of a zwitterionic hydrogel blend with low coefficient of friction.

Science.gov (United States)

Osaheni, Allen O; Finkelstein, Eric B; Mather, Patrick T; Blum, Michelle M

2016-12-01

Hydrogels display a great deal of potential for a wide variety of biomedical applications. Often times the performance of these biomimetic materials is limited due to inferior friction and wear properties. This manuscript presents a method inspired by the tribological phenomena observed in nature for enhancing the lubricious properties of poly(vinyl alcohol) (PVA) hydrogels. This was achieved by blending PVA with various amounts of zwitterionic polymer, poly([2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide) (pMEDSAH). Our results indicate that pMEDSAH acts as an effective boundary lubricant, allowing for reduction in coefficient of friction by more than 80%. This reduction in friction coefficient was achieved while maintaining comparable mechanical and physical properties to that of the neat material. Also, these zwitterionic blends were found to be cytocompatible. Analysis of the structure to property relationships within this system indicate that the zwitterionic polymer served as a boundary lubricant and promoted a reduction in friction through hydration lubrication. This novel approach provides a promising platform for further investigations enhancing the tribological properties of hydrogels for biomedical applications. The novelty of this work stems from showing that zwitterionic polymers can be used as an extremely effective hydrogel boundary lubricant. This work will have significant scientific impact because to date, design of hydrogels has emphasized replication of mechanical properties, but in order for these types of materials to be fully utilized as biomaterials it is imperative that they possess improved tribological and lubrication properties, because ignoring the surface and boundary lubrication mechanism, make these potential load-bearing substitutes incompatible with other natural articulating surfaces, leading the constructs to wear, fail, and damage healthy tissue. Our work also provides unique insight to the structure

Surface modification of silicon wafer by grafting zwitterionic polymers to improve its antifouling property

Science.gov (United States)

Sun, Yunlong; Chen, Changlin; Xu, Heng; Lei, Kun; Xu, Guanzhe; Zhao, Li; Lang, Meidong

2017-10-01

Silicon (111) wafer was modified by triethoxyvinylsilane containing double bond as an intermedium, and then P4VP (polymer 4-vinyl pyridine) brush was "grafted" onto the surface of silicon wafer containing reactive double bonds by adopting the "grafting from" way and Si-P4VP substrate (silicon wafer grafted by P4VP) was obtained. Finally, P4VP brush of Si-P4VP substrate was modified by 1,3-propanesulfonate fully to obtain P4VP-psl brush (zwitterionic polypyridinium salt) and the functional Si-P4VP-psl substrate (silicon wafer grafted by zwitterionic polypyridinium salt based on polymer 4-vinyl pyridine) was obtained successfully. The antifouling property of the silicon wafer, the Si-P4VP substrate and the Si-P4VP-psl substrate was investigated by using bovine serum albumin, mononuclear macrophages (RAW 264.7) and Escherichia coli (E. coli) ATTC25922 as model bacterium. The results showed that compared with the blank sample-silicon wafer, the Si-P4VP-psl substrate had excellent anti-adhesion ability against bovine serum albumin, cells and bacterium, due to zwitterionic P4VP-psl brush (polymer 4-vinyl pyridine salt) having special functionality like antifouling ability on biomaterial field.

Synthesis and solution aggregation studies of a suite of mixed neutral and zwitterionic chromophores for second-order nonlinear optics.

Science.gov (United States)

Peddie, Victoria; Anderson, Jack; Harvey, Joanne E; Smith, Gerald J; Kay, Andrew

2014-11-07

We report details of the synthesis of a series of bi- and trichromophores. These compounds contain mixtures of chromophores that have zwitterionic (ZWI) and neutral ground state (NGS) components covalently attached to each other. The neutral ground state moieties are based on dyes with aniline donors--such as Disperse Red 1--whereas the zwitterionic components are derived from chromophores with pro-aromatic donors such as 1,4-dihydropyridinylidene. By combining both ZWI and NGS components, we aim to develop novel compounds for nonlinear optics in which there is an enhancement of the overall hyperpolarizability coupled with a decrease in the net dipole moment. Thus, this approach should eliminate the electrostatic effects that result when only one type of chromophore is used, and so reduce the likelihood of undesirable aggregation occurring. This, in turn, should enable us to realize organic materials with large macroscopic optical nonlinearities. An analysis of the UV-vis results suggests that there is a strong dependence on solvent polarity that determines whether the embedded constituents should be treated as discrete elements; in low polarity solvents, there appear to be strong intramolecular interactions occurring, particularly when a 1,4-quinolinylidene-based donor is used in the ZWI component.

Modelling zwitterions in solution: 3-fluoro-γ-aminobutyric acid (3F-GABA).

Science.gov (United States)

Cao, Jie; Bjornsson, Ragnar; Bühl, Michael; Thiel, Walter; van Mourik, Tanja

2012-01-02

The conformations and relative stabilities of folded and extended 3-fluoro-γ-aminobutyric acid (3F-GABA) conformers were studied using explicit solvation models. Geometry optimisations in the gas phase with one or two explicit water molecules favour folded and neutral structures containing intramolecular NH···O-C hydrogen bonds. With three or five explicit water molecules zwitterionic minima are obtained, with folded structures being preferred over extended conformers. The stability of folded versus extended zwitterionic conformers increases on going from a PCM continuum solvation model to the microsolvated complexes, though extended structures become less disfavoured with the inclusion of more water molecules. Full explicit solvation was studied with a hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme and molecular dynamics simulations, including more than 6000 TIP3P water molecules. According to free energies obtained from thermodynamic integration at the PM3/MM level and corrected for B3LYP/MM total energies, the fully extended conformer is more stable than folded ones by about -4.5 kJ mol(-1). B3LYP-computed (3)J(F,H) NMR spin-spin coupling constants, averaged over PM3/MM-MD trajectories, agree best with experiment for this fully extended form, in accordance with the original NMR analysis. The seeming discrepancy between static PCM calculations and experiment noted previously is now resolved. That the inexpensive semiempirical PM3 method performs so well for this archetypical zwitterion is encouraging for further QM/MM studies of biomolecular systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-association of an indole based guanidinium-carboxylate-zwitterion: formation of stable dimers in solution and the solid state

Directory of Open Access Journals (Sweden)

Carolin Rether

2010-01-01

Full Text Available The indole based zwitterion 2 forms stable dimers held together by H-bond assisted ion pairs. Dimerisation was confirmed in the solid state and studied in solution using dilution NMR experiments. Even though zwitterion 2 forms very stable dimers even in DMSO, their stability is lower than of an analogous pyrrole based zwitterion 1. As revealed by the X-ray crystal structure the two binding sites in 2 cannot be planar due to steric interactions between the guanidinium group and a neighbouring aromatic CH. Hence the guanidinium moiety is twisted out of planarity from the rest of the molecule forcing the two monomers in dimer 2·2 to interact in a non-ideal orientation. Furthermore, the acidity of the NHs is lower than in 1 (as determined by UV-pH-titration also leading to less efficient binding interactions.

METHOD FOR THE MEASUREMENT OF SITE-SPECIFIC TAUTOMERIC AND ZWITTERIONIC MICROSPECIES EQUILIBRIUM CONSTANTS

Science.gov (United States)

We describe a method for the individual measurement of simultaneously occurring, unimolecular, site-specific “microequilibrium” constants as in, for example, prototropic tautomerism and zwitterionic equilibria. Our method represents an elaboration of that of Nygren et al. (Anal. ...

Proton transport properties in zwitterion blends with Brønsted acids.

Science.gov (United States)

Yoshizawa-Fujita, Masahiro; Byrne, Nolene; Forsyth, Maria; MacFarlane, Douglas R; Ohno, Hiroyuki

2010-12-16

We describe zwitterion, 3-(1-butyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate (Bimps), mixtures with 1,1,1-trifluoro-N-(trifluoromethylsulfonyl)methanesulfoneamide (HN(Tf)(2)) as new proton transport electrolytes. We report proton transport mechanisms in the mixtures based on results from several methods including thermal analyses, the complex-impedance method, and the pulsed field gradient spin echo NMR (pfg-NMR) method. The glass transition temperature (Tg) of the mixtures decreased with increasing HN(Tf)(2) concentration up to 50 mol %. The Tg remained constant at -55 °C with further acid doping. The ionic conductivity of HN(Tf)(2) mixtures increased with the HN(Tf)(2) content up to 50 mol %. Beyond that ratio, the mixtures showed no increase in ionic conductivity (10(-4) S cm(-1) at room temperature). This tendency agrees well with that of Tg. However, the self-diffusion coefficients obtained from the pfg-NMR method increased with HN(Tf)(2) content even above 50 mol % for all component ions. At HN(Tf)(2) 50 mol %, the proton diffusion of HN(Tf)(2) was the fastest in the mixture. These results suggest that Bimps cannot dissociate excess HN(Tf)(2), that is, the excess HN(Tf)(2) exists as molecular HN(Tf)(2) in the mixtures. The zwitterion, Bimps, forms a 1:1 complex with HN(Tf)(2) and the proton transport property in this mixture is superior to those of other mixing ratios. Furthermore, CH(3)SO(3)H and CF(3)SO(3)H were mixed with Bimps for comparison. Both systems showed a similar tendency, which differed from that of the HN(Tf)(2) system. The Tg decreased linearly with increasing acid content for every mixing ratio, while the ionic conductivity increased linearly. Proton transport properties in zwitterion/acid mixtures were strongly affected by the acid species added.

Poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets for electrochemically detecting dopamine at low concentration

Energy Technology Data Exchange (ETDEWEB)

Mao, Hui; Liang, Jiachen; Ji, Chunguang; Zhang, Haifeng; Pei, Qi; Zhang, Yuyang; Zhang, Yu [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Hisaeda, Yoshio [Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Song, Xi-Ming, E-mail: songlab@lnu.edu.cn [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

2016-08-01

Poly(3-(1-vinylimidazolium-3-yl)propane-1-sulfonate) (PVIPS), a novel kind of poly(zwitterionic liquids) (PZILs) containing both imidazolium cation and sulfonate anion, was successfully modified on the surface of polypyrrole/graphene oxide nanosheets (PPy/GO) by covalent bonding. The obtained novel PZILs functionalized PPy/GO nanosheets (PVIPS/PPy/GO) modified glassy carbon electrode (GCE) presented the excellent electrochemical catalytic activity towards dopamine (DA) with high stability, sensitivity, selectivity and wide linear range (40–1220 nM), especially having a lower detection limit (17.3 nM). The excellent analytical performance is attributed to the strongly negative charges on the surface of modified GCE in aqueous solution, which is different from conventional poly(ionic liquids) modified GCE. DA cations could be quickly enriched on the electrode surface by electrostatic interaction in solution due to the existence of −SO{sub 3}{sup −} groups with negative charge at the end of pendant groups in zwitterionic PVIPS, resulting in a change of the electrons transmission mode in the oxidation of DA, that is, from a typical diffusion-controlled process at conventional poly(1-vinyl-3-ethylimidazole bromide) (PVEIB)/PPy/GO modified GCE to a typical surface-controlled process. - Graphical Abstract: Novel poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets were successfully synthesized and presented an excellent performance for determination to DA. Display Omitted - Highlights: • Zwitterionic PVIPS functionalized PPy/GO nanosheets were successfully synthesized. • Their surface charge property has been obviously changed to electronegativity. • The excellent electrochemical catalytic activities towards DA were achieved. • −SO{sub 3}{sup −} groups with negative charge changed the transmission mode of electrons. • PVIPS/PPy/GO can act as an electrode material for detecting DA at low concentration.

Synchronized Regulation of Different Zwitterionic Metabolites in the Osmoadaption of Phytoplankton

Directory of Open Access Journals (Sweden)

Georg Pohnert

2013-06-01

Full Text Available The ability to adapt to different seawater salinities is essential for cosmopolitan marine phytoplankton living in very diverse habitats. In this study, we examined the role of small zwitterionic metabolites in the osmoadaption of two common microalgae species Emiliania huxleyi and Prorocentrum minimum. By cultivation of the algae under salinities between 16‰ and 38‰ and subsequent analysis of dimethylsulfoniopropionate (DMSP, glycine betaine (GBT, gonyol, homarine, trigonelline, dimethylsulfonioacetate, trimethylammonium propionate, and trimethylammonium butyrate using HPLC-MS, we could reveal two fundamentally different osmoadaption mechanisms. While E. huxleyi responded with cell size reduction and a nearly constant ratio between the major metabolites DMSP, GBT and homarine to increasing salinity, osmolyte composition of P. minimum changed dramatically. In this alga DMSP concentration remained nearly constant at 18.6 mM between 20‰ and 32‰ but the amount of GBT and dimethylsulfonioacetate increased from 4% to 30% of total investigated osmolytes. Direct quantification of zwitterionic metabolites via LC-MS is a powerful tool to unravel the complex osmoadaption and regulation mechanisms of marine phytoplankton.

Reaction of iminopropadienones with amines--formation of zwitterionic intermediates, ketenes, and ketenimines.

Science.gov (United States)

Veedu, Rakesh Naduvile; Kokas, Okanya J; Couturier-Tamburelli, Isabelle; Koch, Rainer; Aycard, Jean-Pierre; Borget, Fabien; Wentrup, Curt

2008-10-09

Five aryliminopropadienones 4a- d have been synthesized by flash vacuum thermolysis (FVT) by using two different precursors in each case. These compounds were deposited at 50 K at a pressure of ca. 10(-6) mbar together with three different nucleophiles, namely, trimethylamine (TMA), dimethylamine (DMA), and diethylamine (DEA), in order to study their reactions as neat solids during warm-up by FTIR spectroscopy. The reaction with TMA showed that a zwitterionic species (5 and/or 6) was formed in all the cases. With DMA and DEA, an alpha-oxoketenimine and/or an imidoylketene (7 and 8 or 9 and 10) was formed as the final product. In addition, several bands were observed, which can be assigned to zwitterionic intermediates (11 or 12). Optimized structures and vibrational spectra for all products were calculated at the B3LYP/6-31G(d) level of theory by using the polarizable continuum model (epsilon = 5).

Zwitterion radicals and anion radicals from electron transfer and solvent condensation with the fingerprint developing agent ninhydrin.

Science.gov (United States)

Schertz, T D; Reiter, R C; Stevenson, C D

2001-11-16

Ninhydrin (the fingerprint developing agent) spontaneously dehydrates in liquid ammonia and in hexamethylphosphoramide (HMPA) to form indantrione, which has a sufficiently large solution electron affinity to extract an electron from the solvent (HMPA) to produce the indantrione anion radical. In liquid NH(3), the presence of trace amounts of amide ion causes the spontaneous formation of an anion radical condensation product, wherein the no. 2 carbon (originally a carbonyl carbon) becomes substituted with -NH(2) and -OH groups. In HMPA, the indantrione anion radical spontaneously forms condensation products with the HMPA to produce a variety of zwitterionic radicals, wherein the no. 2 carbon becomes directly attached to a nitrogen of the HMPA. The mechanisms for the formation of the zwitterionic paramagnetic condensation products are analogous to that observed in the reaction of ninhydrin with amino acids to yield Ruhemann's Purple, the contrast product in fingerprint development. The formation of anion and zwitterionic radical condensation products from ninhydrin and nitrogen-containing solvents may represent an example of a host of analogous polyketone-solvent reactions.

Using temperature-responsive zwitterionic surfactant to enhance the enzymatic hydrolysis of lignocelluloses and recover cellulase by cooling.

Science.gov (United States)

Cai, Cheng; Pang, Yuxia; Zhan, Xuejuan; Zeng, Meijun; Lou, Hongming; Qian, Yong; Yang, Dongjie; Qiu, Xueqing

2017-11-01

Some zwitterionic surfactants exhibit upper critical solution temperature (UCST) in aqueous solutions. For the zwitterionic surfactant solution mixed with cellulase, when its temperature is below UCST, the cellulase can be recovered by coprecipitation with zwitterionic surfactant. In this work, 3-(Hexadecyldimethylammonio) propanesulfonate (SB3-16) was selected to enhance the enzymatic hydrolysis of lignocelluloses and recover the cellulase. After adding 2mmol/L of SB3-16, the enzymatic digestibility of eucalyptus pretreated by dilute acid (Eu-DA) and by sulfite (Eu-SPORL) increased from 27.9% and 35.1% to 72.6% and 89.7%, respectively. The results showed that SB3-16 could reduce the non-productive adsorption of cellulase on hydrophobic interface, while it did not significantly inhibit the activity of cellulase. For the solution contained 1wt% SB3-16 and 200mg protein/L CTec2 cellulase, 55.2% of protein could be recovered by cooling. The filter paper activity of the recovered cellulase was 1.93FPU/mg protein, which was 95.8% of its initial activity. Copyright © 2017. Published by Elsevier Ltd.

Quantitative fabrication, performance optimization and comparison of PEG and zwitterionic polymer antifouling coatings.

Science.gov (United States)

Xing, Cheng-Mei; Meng, Fan-Ning; Quan, Miao; Ding, Kai; Dang, Yuan; Gong, Yong-Kuan

2017-09-01

A versatile fabrication and performance optimization strategy of PEG and zwitterionic polymer coatings is developed on the sensor chip of surface plasma resonance (SPR) instrument. A random copolymer bearing phosphorylcholine zwitterion and active ester side chains (PMEN) and carboxylic PEG coatings with comparable thicknesses were deposited on SPR sensor chips via amidation coupling on the precoated polydopamine (PDA) intermediate layer. The PMEN coating showed much stronger resistance to bovine serum albumin (BSA) adsorption than PEG coating at very thin thickness (∼1nm). However, the BSA resistant efficacy of PEG coating could exceed that of PMEN due to stronger steric repelling effect when the thickness increased to 1.5∼3.3nm. Interestingly, both the PEG and PMEN thick coatings (≈3.6nm) showed ultralow fouling by BSA and bovine plasma fibrinogen (Fg). Moreover, changes in the PEG end group from -OH to -COOH, protein adsorption amount could increase by 10-fold. Importantly, the optimized PMEN and PEG-OH coatings were easily duplicated on other substrates due to universal adhesion of the PDA layer, showed excellent resistance to platelet, bacteria and proteins, and no significant difference in the antifouling performances was observed. These detailed results can explain the reported discrepancy in performances between PEG and zwitterionic polymer coatings by thickness. This facile and substrate-independent coating strategy may benefit the design and manufacture of advanced antifouling biomedical devices and long circulating nanocarriers. Prevention of biofouling is one of the biggest challenges for all biomedical applications. However, it is very difficult to fabricate a highly hydrophilic antifouling coating on inert materials or large devices. In this study, PEG and zwitterion polymers, the most widely investigated polymers with best antifouling performance, are conveniently immobilized on different kinds of substrates from their aqueous solutions by

Fabrication of an Anti-Biofouling Plasma-Filtration Membrane by an Electrospinning Process Using Photo-Cross-linkable Zwitterionic Phospholipid Polymers.

Science.gov (United States)

Seo, Jiae; Seo, Ji-Hun

2017-06-14

The goal of this study is to fabricate a stable plasma filtration membrane with antibiofouling properties via an electrospinning process. To this end, a random-type copolymer consisting of zwitterionic phosphorylcholine (PC) groups and ultraviolet (UV)-cross-linkable phenyl azide groups was synthesized. The zwitterionic PC group provides antibiofouling properties, and the phenyl azide group enables the stable maintenance of the fibrous nanostructure of hydrophilic zwitterion polymers in aqueous medium via a simple UV curing process. To demonstrate the antibiofouling nature of the PC group, a polymer without antibiofouling PC groups was also prepared for comparison. The successful synthesis of the random-type copolymers containing phenyl azide groups was proven by 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy, and the fibrous structure of the prepared membranes was observed by field emission scanning electron microscopy. The antibiofouling properties were analyzed by fluorescein isothiocyanate-labeled bovine serum albumin adsorption and platelet adhesion tests. The experimental results show that membranes containing zwitterionic PC groups exhibited obvious decreases in platelet adhesion and protein adsorption. Platelet-rich plasma solution was filtered using the prepared membranes to test their filtration properties. The sequential filtration process removed 80% and almost 98% of the platelets. This finding confirmed that the membrane retained its blood-inert biomaterial surface in a complex medium that included blood plasma and platelets.

Increments to chiral recognition facilitating enantiomer separations of chiral acids, bases, and ampholytes using Cinchona-based zwitterion exchanger chiral stationary phases.

Science.gov (United States)

Wernisch, Stefanie; Pell, Reinhard; Lindner, Wolfgang

2012-07-01

The intramolecular distances of anion and cation exchanger sites of zwitterionic chiral stationary phases represent potential tuning sites for enantiomer selectivity. In this contribution, we investigate the influence of alkanesulfonic acid chain length and flexibility on enantiomer separations of chiral acids, bases, and amphoteric molecules for six Cinchona alkaloid-based chiral stationary phases in comparison with structurally related anion and cation exchangers. Employing polar-organic elution conditions, we observed an intramolecular counterion effect for acidic analytes which led to reduced retention times but did not impair enantiomer selectivities. Retention of amphoteric analytes is based on simultaneous double ion pairing of their charged functional groups with the acidic and basic sites of the zwitterionic selectors. A chiral center in the vicinity of the strong cation exchanger site is vital for chiral separations of bases. Sterically demanding side chains are beneficial for separations of free amino acids. Enantioseparations of free (un-derivatized) peptides were particularly successful in stationary phases with straight-chain alkanesulfonic acid sites, pointing to a beneficial influence of more flexible moieties. In addition, we observed pseudo-enantiomeric behavior of quinine and quinidine-derived chiral stationary phases facilitating reversal of elution orders for all analytes. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular Recognition of Vesicles : Host-Guest Interactions Combined with Specific Dimerization of Zwitterions

NARCIS (Netherlands)

Voskuhl, Jens; Fenske, Tassilo; Stuart, Marc C. A.; Wibbeling, Birgit; Schmuck, Carsten; Ravoo, Bart Jan

2010-01-01

The aggregation of beta-cyclodextrin vesicles can be induced by an adamantyl-substituted zwitterionic guanidiniocarbonylpyrrole carboxylate guest molecule (1). Upon addition of 1 to the cyclodextrin vesicles at neutral pH, the vesicles aggregate (but do not fuse), as shown by using UV/Vis and

Electronic nature of zwitterionic alkali metal methanides, silanides and germanides - a combined experimental and computational approach.

Science.gov (United States)

Li, H; Aquino, A J A; Cordes, D B; Hase, W L; Krempner, C

2017-02-01

Zwitterionic group 14 complexes of the alkali metals of formula [C(SiMe 2 OCH 2 CH 2 OMe) 3 M], (M- 1 ), [Si(SiMe 2 OCH 2 CH 2 OMe) 3 M], (M- 2 ), [Ge(SiMe 2 OCH 2 CH 2 OMe) 3 M], (M- 3 ), where M = Li, Na or K, have been prepared, structurally characterized and their electronic nature was investigated by computational methods. Zwitterions M- 2 and M- 3 were synthesized via reactions of [Si(SiMe 2 OCH 2 CH 2 OMe) 4 ] ( 2 ) and [Ge(SiMe 2 OCH 2 CH 2 OMe) 4 ] ( 3 ) with MOBu t (M = Li, Na or K), resp., in almost quantitative yields, while M- 1 were prepared from deprotonation of [HC(SiMe 2 OCH 2 CH 2 OMe) 3 ] ( 1 ) with LiBu t , NaCH 2 Ph and KCH 2 Ph, resp. X-ray crystallographic studies and DFT calculations in the gas-phase, including calculations of the NPA charges confirm the zwitterionic nature of these compounds, with the alkali metal cations being rigidly locked and charge separated from the anion by the internal OCH 2 CH 2 OMe donor groups. Natural bond orbital (NBO) analysis and the second order perturbation theory analysis of the NBOs reveal significant hyperconjugative interactions in M- 1 -M- 3 , primarily between the lone pair and the antibonding Si-O orbitals, the extent of which decreases in the order M- 1 > M- 2 > M- 3 . The experimental basicities and the calculated gas-phase basicities of M- 1 -M- 3 reveal the zwitterionic alkali metal methanides M- 1 to be significantly stronger bases than the analogous silanides M- 2 and germanium M- 3 .

Zwitterions as alternative draw solutions in forward osmosis for application in wastewater reclamation

NARCIS (Netherlands)

Lutchmiah, K.; Lauber, L.; Roest, de K.; Harmsen, D.J.H.; Post, J.W.; Rietveld, L.C.; Lier, van J.B.; Cornelissen, E.R.

2014-01-01

The draw solution is the driving force in forward osmosis (FO) processes. The reverse solute leakage of the draw solution is however a major constraint due to cost and energy requirements when reconcentrating the solutes subsequent to the FO process. Several zwitterions as draw solutions (pi

Corrosion inhibition of iota-carrageenan natural polymer on aluminum in presence of zwitterion mediator in HCl media

International Nuclear Information System (INIS)

Fares, Mohammad M.; Maayta, A.K.; Al-Mustafa, Jamil A.

2012-01-01

Highlights: ► Inhibition of Al by ι-carrageenan in the presence of zwitterion mediator was investigated. ► Considerable improvement in inhibition efficiency observed in the presence of zwitterion mediator. ► Coherent physical adsorption layer was evidenced by kinetic and thermodynamic parameters. ► Small but consistent fractured island layers observed after acid exposure as revealed by SEM images. - Abstract: ι-Carrageenan a natural polymer has been used as corrosion inhibitor of aluminum in presence of pefloxacin mesylate, acting as zwitterionic mediator, in acidic medium. Considerable improvement in inhibition efficiency occurred in the presence of the mediator. Activation energy of corrosion and other thermodynamic parameters such as standard free energy, standard enthalpy, and standard entropy of the adsorption process revealed better and well-ordered physical adsorption layers in presence of pefloxacin. Adsorption isotherms in absence or presence of pefloxacin mediator appropriately fit in the Langmuir isotherms. The scanning electron microscope (SEM) images demonstrated smooth, glossy, and relatively coherent adsorption layers of the inhibitor on the metal surface in aqueous solution. After the exposure to 2.0 M HCl for 2 h, a smaller but consistent regular shaped fractured layer is obtained.

Hemocompatibility improvement of poly(ethylene terephthalate) via self-polymerization of dopamine and covalent graft of zwitterions

Energy Technology Data Exchange (ETDEWEB)

Cai, Xianmei; Yuan, Jiang, E-mail: bioalchem@yahoo.com; Chen, Shuangchun; Li, Pengfei; Li, Li, E-mail: lili3@njnu.edu.cn; Shen, Jian

2014-03-01

Poly (ethylene terephthalate) (PET) has been widely adopted as a scaffold biomaterial, but further hemocompatibility improvement is still needed for wide biomedical applications. Inspired by the composition of adhesive proteins in mussels, we propose to use self-polymerized dopamine to form a surface-adherent polydopamine layer onto PET sheet, followed by Michael addition with N,N-dimethylethylenediamine (DMDA) to build tertiary amine, and final zwitterions(sulfobetaine and carboxybetaine) construction through ring-opening reaction. Physicochemical properties of substrates were demonstrated by water contact angle measurement, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The hemocompatibility was evaluated by platelet adhesion, hemolytic, and protein adsorption. The results showed that the zwitterions immobilized PET endowed with improved resistance to nonspecific protein adsorption and platelet adhesion as well as nonhemolytic. The zwitterions with desirable hemocompatibility can be readily tailored to catheter for various biomedical applications. - Highlights: • We first used self-polymerized dopamine to form a thin and surface-adherent polydopamine layer onto PET film. • Then, DMDA was attached to the PET surface by Michael addition. • Sulfobetaine and carboxybetaine were finally constructed through ring-opening reaction. • The modify PET endowed with improved resistance to nonspecific protein adsorption and platelet adhesion.

On the freezing behavior and diffusion of water in proximity to single-supported zwitterionic and anionic bilayer lipid membranes

DEFF Research Database (Denmark)

Miskowiec, A.; Buck, Z. N.; Brown, M. C.

2014-01-01

We compare the freezing/melting behavior of water hydrating single-supported bilayers of a zwitterionic lipid DMPC with that of an anionic lipid DMPG. For both membranes, the temperature dependence of the elastically scattered neutron intensity indicates distinct water types undergoing...... translational diffusion: bulk-like water probably located above the membrane and two types of confined water closer to the lipid head groups. The membranes differ in the greater width of the water freezing transition near the anionic DMPG bilayer compared to zwitterionic DMPC as well as in the abruptness...

The structure of ions and zwitterionic lipids regulates the charge of dipolar membranes.

Science.gov (United States)

Szekely, Or; Steiner, Ariel; Szekely, Pablo; Amit, Einav; Asor, Roi; Tamburu, Carmen; Raviv, Uri

2011-06-21

In pure water, zwitterionic lipids form lamellar phases with an equilibrium water gap on the order of 2 to 3 nm as a result of the dominating van der Waals attraction between dipolar bilayers. Monovalent ions can swell those neutral lamellae by a small amount. Divalent ions can adsorb onto dipolar membranes and charge them. Using solution X-ray scattering, we studied how the structure of ions and zwitterionic lipids regulates the charge of dipolar membranes. We found that unlike monovalent ions that weakly interact with all of the examined dipolar membranes, divalent and trivalent ions adsorb onto membranes containing lipids with saturated tails, with an association constant on the order of ∼10 M(-1). One double bond in the lipid tail is sufficient to prevent divalent ion adsorption. We suggest that this behavior is due to the relatively loose packing of lipids with unsaturated tails that increases the area per lipid headgroup, enabling their free rotation. Divalent ion adsorption links two lipids and limits their free rotation. The ion-dipole interaction gained by the adsorption of the ions onto unsaturated membranes is insufficient to compensate for the loss of headgroup free-rotational entropy. The ion-dipole interaction is stronger for cations with a higher valence. Nevertheless, polyamines behave as monovalent ions near dipolar interfaces in the sense that they interact weakly with the membrane surface, whereas in the bulk their behavior is similar to that of multivalent cations. Advanced data analysis and comparison with theory provide insight into the structure and interactions between ion-induced regulated charged interfaces. This study models biologically relevant interactions between cell membranes and various ions and the manner in which the lipid structure governs those interactions. The ability to monitor these interactions creates a tool for probing systems that are more complex and forms the basis for controlling the interactions between dipolar

Neutral, anionic, cationic, and zwitterionic diblock copolymers featuring poly(2-methoxyethyl acrylate) hydrophobic segments

DEFF Research Database (Denmark)

Javakhishvili, Irakli; Jankova Atanasova, Katja; Hvilsted, Søren

2013-01-01

-b-PDMAEMA while the betainisation of the latter provides zwitterionic diblock amphiphile PMEA-b-PDMAPS. Inspection of these macromolecular architectures by NMR spectroscopy and size exclusion chromatography (SEC) confirms a fairly high degree of control over the reactions emphasizing flexibility and precision...

Preparation of dispersible graphene through organic functionalization of graphene using a zwitterion intermediate cycloaddition approach

NARCIS (Netherlands)

Zhang, Xiaoyan; Browne, Wesley R.; Feringa, Ben L.

2012-01-01

Highly functionalized graphene were obtained through a zwitterion intermediate cycloaddition onto exfoliated graphene flakes under new reaction conditions. The functionalized graphene obtained formed stable dispersions in common solvents, including dimethylformamide (DMF), CHCl3 and water. Its

Metal-Ligand Cooperative Reactivity in the (pseudo)-Dearomatized PNX(P) Systems: the Influence of the Zwitterionic Form in Dearomatized Pincer Complexes

KAUST Repository

Goncalves, Theo

2017-09-01

The concept of aromaticity in pincer ligands and complexes was discussed in order to provide insights into their metal-ligand cooperative activities. The aromatic PNx(P) and dearomatized PNx(P)* pincer ligands and the corresponding transition metal complexes were studied with the nucleus-independent chemical shift (NICSzz), anisotropy of the current (induced) density (ACID), isochemical shielding surfaces (ICSSzz), harmonic oscillator model of aromaticity (HOMA), MCBO, Shannon aromaticity, and natural bond order (NBO) analyses. The study on the model systems showed that for the dearomatized species the decrease of the NICS(1)zz value comes with the larger contribution of the aromatic zwitterionic mesomeric form. In all examples, the incorporation of the metal center into the pincer ligand decreases the NICS(1)zz values. The DFT calculations support the dearomatized pyridine ring in PNP* or PNN* ligand indeed being nonaromatic, in contrast to the PN3(P)* ligand which has partial aromatic character due to the larger contribution of the zwitterionic resonance structure. The difference in aromaticity between the rings contributes to the thermodynamic balance of the metal ligand cooperative reactions, changing the energetics of the process when different dearomatized pincer ligands are used. This was further exemplified by aromaticity analysis of the heterolytic hydrogen cleavage reaction of ruthenium PNN complexes of Milstein and the PN3 of Huang, with similar geometries but distinctive thermodynamic preference.

Metal-Ligand Cooperative Reactivity in the (pseudo)-Dearomatized PNX(P) Systems: the Influence of the Zwitterionic Form in Dearomatized Pincer Complexes

KAUST Repository

Goncalves, Theo; Huang, Kuo-Wei

2017-01-01

The concept of aromaticity in pincer ligands and complexes was discussed in order to provide insights into their metal-ligand cooperative activities. The aromatic PNx(P) and dearomatized PNx(P)* pincer ligands and the corresponding transition metal complexes were studied with the nucleus-independent chemical shift (NICSzz), anisotropy of the current (induced) density (ACID), isochemical shielding surfaces (ICSSzz), harmonic oscillator model of aromaticity (HOMA), MCBO, Shannon aromaticity, and natural bond order (NBO) analyses. The study on the model systems showed that for the dearomatized species the decrease of the NICS(1)zz value comes with the larger contribution of the aromatic zwitterionic mesomeric form. In all examples, the incorporation of the metal center into the pincer ligand decreases the NICS(1)zz values. The DFT calculations support the dearomatized pyridine ring in PNP* or PNN* ligand indeed being nonaromatic, in contrast to the PN3(P)* ligand which has partial aromatic character due to the larger contribution of the zwitterionic resonance structure. The difference in aromaticity between the rings contributes to the thermodynamic balance of the metal ligand cooperative reactions, changing the energetics of the process when different dearomatized pincer ligands are used. This was further exemplified by aromaticity analysis of the heterolytic hydrogen cleavage reaction of ruthenium PNN complexes of Milstein and the PN3 of Huang, with similar geometries but distinctive thermodynamic preference.

Development of Low Fouling and High Fouling-release Zwitterionic Marine Coatings

Science.gov (United States)

2016-01-04

amount, pigment , crosslinker type and catalyst amount. The details are shown below, 1. PDMS coating with zwitterionic copolymer incorporated. PDMS...onto aluminum panels. The coating can be cured within 3.5 hours. 2. PDMS coating with pigment incorporated. Various amount of the pigment cadmium...stirred vigorously until all the solid were dispersed uniformly. The obtained viscous liquid was then mixed with 3 g PDMS crosslinker, and applied onto

Electrokinetic Phenomena in Chemically Manipulated Environments

Science.gov (United States)

Nery Azevedo, Rodrigo

Suspended particles are integral part of many systems and engineering technologies. They can be found in the form of colloidal suspensions, emulsions, polymer precursor solutions, and in biological materials such as blood. The miniaturization of new technologies and the advent of microfludics has made the manipulation of suspended particles in the microscale particularly important for a variety of fields. The ability to easily impart complex chemical environments to suspensions in microfluidic devices enables us to characterize these systems, modify their properties and drive their motion. Nonetheless, precise manipulation of the chemistry surrounding suspended particles has been particularly difficult up until recently. This thesis dissertation shows how microfluidic devices integrated with hydrogel membranes can be used to control the chemical environment of suspended particles for a variety of studies and practical applications. First, I demonstrate how particles move diffusiophoretically under ionic surfactant gradients. Diffusiophoresis, the motion of particles under concentration gradients, has been known for several decades but it has rarely been studied experimentally outside the context of simple electrolytes. Here, we show that diffusiophoresis in ionic surfactants below the CMC can be understood in terms of the classic theory for electrolytes. Above the CMC, however, the drive for diffsuiophoresis is significantly diminished due to a large drop in the change in chemical potential with added solute. Next, I show that gradients of dipolar molecules such a zwitterions can drive diffusiophoresis. I derive the diffusiophoretic migration of particles under gradients of dipolar molecules. This theory is backed up by experiments which reveal that, in such systems, particle velocities are directly proportional to the imposed gradient but do not scale with the inverse of the local concentration, as occurs under electrolyte gradients. Furthermore, I show that the

Silica Nanoparticles Functionalized with Zwitterionic Sulfobetaine Siloxane for Application as a Versatile Antifouling Coating System.

Science.gov (United States)

Knowles, Brianna R; Wagner, Pawel; Maclaughlin, Shane; Higgins, Michael J; Molino, Paul J

2017-06-07

The growing need to develop surfaces able to effectively resist biological fouling has resulted in the widespread investigation of nanomaterials with potential antifouling properties. However, the preparation of effective antifouling coatings is limited by the availability of reactive surface functional groups and our ability to carefully control and organize chemistries at a materials' interface. Here, we present two methods of preparing hydrophilic low-fouling surface coatings through reaction of silica-nanoparticle suspensions and predeposited silica-nanoparticle films with zwitterionic sulfobetaine (SB). Silica-nanoparticle suspensions were functionalized with SB across three pH conditions and deposited as thin films via a simple spin-coating process to generate hydrophilic antifouling coatings. In addition, coatings of predeposited silica nanoparticles were surface functionalized via exposure to zwitterionic solutions. Quartz crystal microgravimetry with dissipation monitoring was employed as a high throughput technique for monitoring and optimizing reaction to the silica-nanoparticle surfaces. Functionalization of nanoparticle films was rapid and could be achieved over a wide pH range and at low zwitterion concentrations. All functionalized particle surfaces presented a high degree of wettability and resulted in large reductions in adsorption of bovine serum albumin protein. Particle coatings also showed a reduction in adhesion of fungal spores (Epicoccum nigrum) and bacteria (Escherichia coli) by up to 87 and 96%, respectively. These results indicate the potential for functionalized nanosilicas to be further developed as versatile fouling-resistant coatings for widespread coating applications.

Biorefineries for the production of top building block chemicals and their derivatives

DEFF Research Database (Denmark)

Choi, Sol; Song, Chan Woo; Shin, Jae Ho

2015-01-01

commercialized or are close to commercialization. In this paper, we review the current status of biorefinery development for the production of these platform chemicals and their derivatives. In addition, current technological advances on industrial strain development for the production of platform chemicals...... years after its announcement, many studies have been performed for the development of efficient technologies for the bio-based production of these chemicals and derivatives. Now, ten chemicals among these top 12 chemicals, excluding the l-aspartic acid and 3-hydroxybutyrolactone, have already been...

Molecular dynamics simulations of the helical antimicrobial peptide ovispirin-1 in a zwitterionic dodecylphosphocholine micelle

DEFF Research Database (Denmark)

Khandelia, Himanshu; Kaznessis, Yiannis N

2005-01-01

We have carried out a 40-ns all-atom molecular dynamics simulation of the helical antimicrobial peptide ovispirin-1 (OVIS) in a zwitterionic diphosphocholine (DPC) micelle. The DPC micelle serves as an economical and effective model for a cellular membrane owing to the presence of a choline...... headgroup, which resembles those of membrane phospholipids. OVIS, which was initially placed along a micelle diameter, diffuses out to the water-DPC interface, and the simulation stabilizes to an interface-bound steady state in 40 ns. The helical content of the peptide marginally increases in the process...... in the micellar core and the polar side chains protruding into the aqueous phase. There is overwhelming evidence that points to the significant and indispensable participation of hydrophobic residues in binding to the zwitterionic interface. The simulation starts with a conformation that is unbiased toward...

Kinetics of CO2 with primary and secondary amines in aqueous solutions I. Zwitterion deprotonation kinetics for DEA and DIPA in aqueous blends of alkanolamines

NARCIS (Netherlands)

Littel, R.J.; Littel, R.J.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

1992-01-01

The deprotonation kinetics of the DEA—CO2 and the DIPA—CO2 zwitterions have been studied in aqueous blends of amines at 298 K. Amine mixtures investigated were: DEA—TEA, DEA—MDEA, DEA—DMMEA, DEA—DEMEA, DIPA—TEA. DIPA—MDEA, DIPA—DMMEA, DIPA—DEMEA. For each blend the zwitterion deprotonation constant

Kinetics of CO2 with primary and secondary amines in aqueous solutions—I. Zwitterion deprotonation kinetics for DEA and DIPA in aqueous blends of alkanolamines

NARCIS (Netherlands)

Littel, R.J.; Versteeg, G.F.; Swaaij, W.P.M. van

1992-01-01

The deprotonation kinetics of the DEA—CO2 and the DIPA—CO2 zwitterions have been studied in aqueous blends of amines at 298 K. Amine mixtures investigated were: DEA—TEA, DEA—MDEA, DEA—DMMEA, DEA—DEMEA, DIPA—TEA. DIPA—MDEA, DIPA—DMMEA, DIPA—DEMEA. For each blend the zwitterion deprotonation constant

Development of zwitterionic chromophores for electro-optic applications

Science.gov (United States)

Xiong, Ying

In order to unlock the full potential of the zwitterionic NLO chromophores for electro-optic (EO) applications, a new series of PeQDM chromophores with large first hyperpolarizabilities (beta0 ˜ 600 x 10-30 esu) have been designed and synthesized. A large EO coefficient (r33) of 110 pm/V at 1550 nm has been realized with a 5 wt% (corresponding to 3.8 wt% core content) chromophore doped polymer. The EO study of guest-host polymers reveals that dipolar dye aggregation in a less polar medium is responsible for a low chromophore loading and low EO activity. Modification of NLO chromophore by attaching large dendrons can effectively increase the chromophore loading in a host and improve the poling efficiency. Crosslinkable NLO polymers have also been prepared to improve the temporal stability of the poled noncentrosymmetric order. The following are some important highlights from this thesis work. (1) A series of thermally stable zwitterionic chromophores (PeQDM) with large first hyperpolarizabilities (beta up to -1797 x 10-30 esu) are synthesized in good yields (˜ 50%). The charge-separated ground state is evident by a negative solvatochromism. X-ray crystallographic data further confirms the zwitterionic nature and demonstrates a face-to-face anti-parallel H-aggregation of two monomers due to strong electrostatic interactions between the dipoles. (2) PeQDM chromophores are also NIR fluorescent (lambdaPL ˜ 840-870 nm in solution) and labile to acid, making them potential candidates for NIR pH sensor applications. (3) The hydroxyl-containing PeQDM chromophores are modified with ES-dendron, which exhibit good solubility in solvents and polymers. Self-forming films can be prepared by direct casting or spin-coating of two dendrons modified chromophores (ES-PeQDM-2 and ES-PeQDM-3), in which the chromophore core contents reach 14.9 and 16.9 wt%, respectively. Compared to ES-PeQDM-2 with two dendrons only at the donor part (r33 = 0 pm/V), ES-PeQDM-3 with the bulky ES

Production of Fatty Acid-Derived Valuable Chemicals in Synthetic Microbes

International Nuclear Information System (INIS)

Yu, Ai-Qun; Pratomo Juwono, Nina Kurniasih; Leong, Susanna Su Jan; Chang, Matthew Wook

2014-01-01

Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters, and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants, and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed: (i) the current status of metabolic engineering of microbes that produce fatty acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes.

Production of Fatty Acid-Derived Valuable Chemicals in Synthetic Microbes

Energy Technology Data Exchange (ETDEWEB)

Yu, Ai-Qun; Pratomo Juwono, Nina Kurniasih [Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (Singapore); Synthetic Biology Research Program, National University of Singapore, Singapore (Singapore); Leong, Susanna Su Jan [Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (Singapore); Synthetic Biology Research Program, National University of Singapore, Singapore (Singapore); Singapore Institute of Technology, Singapore (Singapore); Chang, Matthew Wook, E-mail: bchcmw@nus.edu.sg [Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (Singapore); Synthetic Biology Research Program, National University of Singapore, Singapore (Singapore)

2014-12-23

Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters, and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants, and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed: (i) the current status of metabolic engineering of microbes that produce fatty acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes.

New carboxy-functionalized terpyridines as precursors for zwitterionic ruthenium complexes for polymer-based solar cells

DEFF Research Database (Denmark)

Duprez, V.; Krebs, Frederik C

2006-01-01

New carboxy-terpyridines selectively functionalized at the 4-, 4'- and 4"-positions were prepared in a three-step procedure with good yields using, the Krohnke reaction followed by saponification. Their complexation with ruthenium led to symmetric and unsymmetric terpyridinyl zwitterionic complexes...

Zwitterionic polyacrylamides: synthesis, study of their properties in aqueous solution, study of their adsorption on clay particles; Derives zwitterioniques du polyacrylamide. Synthese et etude des proprietes en solution aqueuse et de l'adsorption sur argile

Energy Technology Data Exchange (ETDEWEB)

Carrette, P.L.

1998-12-10

Some zwitterionic polyacrylamides have been prepared and studied in aqueous solution. They are neutral polymers, whose charges are on the same lateral group: the positive charge is a quaternary ammonium and the negative charge is a phosphonate or a sulfonate group. Such poly-betaines have a zero net charge on a wide range of pH. They are prepared in salt-free aqueous solution by radical copolymerization of acrylamide with 3-[3-acrylamide-(propyl)dimethyl-ammonio] propane ethyl phosphate or 3-[3-acrylamide-(propyl)dimethyl-ammonio] propane sulfonate. The study has been restricted to copolymers with 1 to 10 % zwitterionic units and weight average molar masses between 1 and 2.10{sup 6} g/mol. The reactivity ratios have been determined. Their properties in solution and their adsorption on clay particles have been compared to the properties of polyacrylamide and partly hydrolyzed polyacrylamide. The use of the later polymers in petroleum industry is limited by the decrease of viscosity in presence of electrolytes, the precipitation with multi-valent cations and an important sensibility to the hydrolysis at basic pH and/or at high temperature. The rheological properties of zwitterionic polymers are controlled by electrostatic attractive forces between charges of opposite signs. Their viscosity increases as a function of ionic strength: the salts screen these attractive forces, increasing in this way the hydrodynamic volume (anti-polyelectrolyte behaviour). At high shear rates, their viscosity decreases less than in the case of usual polyacrylamide. Moreover, their resistance to hydrolysis is better and the precipitation by calcium salts is avoided unlike others charged polymers such as partly hydrolyzed polyacrylamides. Finally, their adsorption on clay particles (montmorillonite) is always twice higher than polyacrylamide adsorption whatever the salinity and the nature of salt (NaCl or KCl). In conclusion, even with small rates the incorporation of zwitterionic units in

New Chiral Zwitterionic Phosphorus Heterocycles: Synthesis, Structure, Properties and Application as Chiral Solvating Agents

Czech Academy of Sciences Publication Activity Database

Sheshenev, A. E.; Boltukhina, E. V.; Grishina, Anastasia; Císařová, I.; Lyapkalo, Ilya; Hii, K. K.

2013-01-01

Roč. 19, č. 25 (2013), s. 8136-8143 ISSN 0947-6539 Grant - others:7th European Community Framework Programme(XE) FP7-252247 Institutional support: RVO:61388963 Keywords : binding constants * chirality * enantioselectivity * NMR spectroscopy * phosphorus heterocycles * zwitterions Subject RIV: CC - Organic Chemistry Impact factor: 5.696, year: 2013

Non-fouling hydrogels of 2-hydroxyethyl methacrylate and zwitterionic carboxybetaine (meth)acrylamides

Czech Academy of Sciences Publication Activity Database

Kostina, Nina Yu.; Rodriguez-Emmenegger, Cesar; Houska, Milan; Brynda, Eduard; Michálek, Jiří

2012-01-01

Roč. 13, č. 12 (2012), s. 4164-4170 ISSN 1525-7797 R&D Projects: GA AV ČR KAN200520804; GA ČR GAP205/12/1702; GA ČR GAP106/12/1451 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : zwitterionic hydrogels * non-fouling properties * carboxybetaine Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.371, year: 2012

Hemocompatible control of sulfobetaine-grafted polypropylene fibrous membranes in human whole blood via plasma-induced surface zwitterionization.

Science.gov (United States)

Chen, Sheng-Han; Chang, Yung; Lee, Kueir-Rarn; Wei, Ta-Chin; Higuchi, Akon; Ho, Feng-Ming; Tsou, Chia-Chun; Ho, Hsin-Tsung; Lai, Juin-Yih

2012-12-21

In this work, the hemocompatibility of zwitterionic polypropylene (PP) fibrous membranes with varying grafting coverage of poly(sulfobetaine methacrylate) (PSBMA) via plasma-induced surface polymerization was studied. Charge neutrality of PSBMA-grafted layers on PP membrane surfaces was controlled by the low-pressure and atmospheric plasma treatment in this study. The effects of grafting composition, surface hydrophilicity, and hydration capability on blood compatibility of the membranes were determined. Protein adsorption onto the different PSBMA-grafted PP membranes from human fibrinogen solutions was measured by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. Blood platelet adhesion and plasma clotting time measurements from a recalcified platelet-rich plasma solution were used to determine if platelet activation depends on the charge bias of the grafted PSBMA layer. The charge bias of PSBMA layer deviated from the electrical balance of positively and negatively charged moieties can be well-controlled via atmospheric plasma-induced interfacial zwitterionization and was further tested with human whole blood. The optimized PSBMA surface graft layer in overall charge neutrality has a high hydration capability and keeps its original blood-inert property of antifouling, anticoagulant, and antithrmbogenic activities when it comes into contact with human blood. This work suggests that the hemocompatible nature of grafted PSBMA polymers by controlling grafting quality via atmospheric plasma treatment gives a great potential in the surface zwitterionization of hydrophobic membranes for use in human whole blood.

Preparation and structural characterization of zwitterionic surfactant intercalated into NiZn-layered hydroxide salts

Science.gov (United States)

Liu, Jiexiang; Wang, Jianlong; Zhang, Xiaoguang; Fang, Binbin; Hu, Pan; Zhao, Xuyang

2015-10-01

Three zwitterionic surfactants, dodecyl dimethyl carboxylbetaine (DCB), dodecyl dimethyl sulfobetaine (DSB) and N-dodecyl-β-aminoprpionate (DAP), intercalated into NiZn-layered hydroxide salts (NZL-DCB, NZL-DSB and NZL-DAP) were synthesized by the coprecipitation method. The effect of surfactant content, pH, temperature and time of hydrothermal treatment on preparation was investigated and discussed. The NZL-DCB, NZL-DSB and NZL-DAP were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry analysis and differential thermal analysis (TGA/DTA). The results showed that basal spacings of NZL-DCB, NZL-DSB and NZL-DAP were around 3.45, 3.68 and 3.94 nm, respectively. DCB, DSB and DAP probably form an overlapped bilayer in the gallery. TGA/DTA data indicated that NZL-DCB, NZL-DSB and NZL-DAP displayed three loss weight stages: loss of adsorbed and structural water, dehydroxylation of matrix and decomposition of nitrate ions, decomposition and combustion of surfactants. Furthermore, chemical analysis data, BET surface area and scanning electron microscopic (SEM) were also measured and analyzed.

PHYSICO-CHEMICAL STUDIES OF DISAZO DYES DERIVED ...

African Journals Online (AJOL)

DJFLEX

with disazo disperse dyes on synthetic polymer-fibres. (Venkataraman, 1974; Otutu et al., 2008). In this present study, the physico-chemical studies of disazo dyes derived from p-aminophenol recently prepared by our research group is described. We also described the kinetics of the dyes on nylon 6 fibre. In another study.

Zwitterionic sulfobetaine polymer-immobilized surface by simple tyrosinase-mediated grafting for enhanced antifouling property.

Science.gov (United States)

Kwon, Ho Joon; Lee, Yunki; Phuong, Le Thi; Seon, Gyeung Mi; Kim, Eunsuk; Park, Jong Chul; Yoon, Hyunjin; Park, Ki Dong

2017-10-01

Introducing antifouling property to biomaterial surfaces has been considered an effective method for preventing the failure of implanted devices. In order to achieve this, the immobilization of zwitterions on biomaterial surfaces has been proven to be an excellent way of improving anti-adhesive potency. In this study, poly(sulfobetaine-co-tyramine), a tyramine-conjugated sulfobetaine polymer, was synthesized and simply grafted onto the surface of polyurethane via a tyrosinase-mediated reaction. Surface characterization by water contact angle measurements, X-ray photoelectron spectroscopy and atomic force microscopy demonstrated that the zwitterionic polymer was successfully introduced onto the surface of polyurethane and remained stable for 7days. In vitro studies revealed that poly(sulfobetaine-co-tyramine)-coated surfaces dramatically reduced the adhesion of fibrinogen, platelets, fibroblasts, and S. aureus by over 90% in comparison with bare surfaces. These results proved that polyurethane surfaces grafted with poly(sulfobetaine-co-tyramine) via a tyrosinase-catalyzed reaction could be promising candidates for an implantable medical device with excellent bioinert abilities. Antifouling surface modification is one of the key strategy to prevent the thrombus formation or infection which occurs on the surface of biomaterial after transplantation. Although there are many methods to modify the surface have been reported, necessity of simple modification technique still exists to apply for practical applications. The purpose of this study is to modify the biomaterial's surface by simply immobilizing antifouling zwitterion polymer via enzyme tyrosinase-mediated reaction which could modify versatile substrates in mild aqueous condition within fast time period. After modification, pSBTA grafted surface becomes resistant to various biological factors including proteins, cells, and bacterias. This approach appears to be a promising method to impart antifouling property on

A molecular receptor selective for zwitterionic alanine.

Science.gov (United States)

Rubio, Omayra H; Taouil, Rachid; Muñiz, Francisco M; Monleón, Laura M; Simón, Luis; Sanz, Francisca; Morán, Joaquín R

2017-01-04

A molecular receptor has been synthesized joining an aza-crown ether with a chiral chromane which mimics the oxyanion hole of the enzymes. With this receptor an apolar host-guest complex with zwitterionic alanine has been achieved through the formation of up to seven H-bonds. This complex allows the extraction of aqueous alanine to a chloroform phase, while other natural amino acids are poorly extracted or are not extracted at all. Due to the chiral nature of the receptor, enantioselective extraction from the aqueous alanine solution to a chloroform phase takes place. X-Ray analysis combined with anisotropic effects, NOE and CD studies revealed the absolute configuration of both strong and weak complexes. Modelling studies also support the proposed structures. The presence of an oxyanion-hole motif in this structure was corroborated by X-ray diffraction studies.

Exudate Chemical Profiles Derived from Lespedeza and Other Tallgrass Prairie Plant Species

Science.gov (United States)

2017-05-01

Chemical Profiles Derived from Lespedeza and Other Tall- grass Prairie Plant Species. ERDC TN-17-1. Vicksburg, MS: U.S. Army Engineer Re- search and...200-1-52. Washington, DC: U.S. Army Corps of Engineers Headquarters, Civil Works. https://www.wbdg.org/ffc/army-coe/public-works-technical-bulletins...ERDC TN-17-1 May 2017 Approved for public release; distribution is unlimited. Exudate Chemical Profiles Derived from Lespedeza and Other

Palladium catalyst system comprising zwitterion and/or acid-​functionalized ionic liquid

DEFF Research Database (Denmark)

2011-01-01

The present invention concerns a catalyst system in particular a catalyst system comprising Palladium (Pd), a zwitterion and/or an acid-functionalized ionic liquid, and one or more phosphine ligands, wherein the Pd catalyst can be provided by a complex precursor, such as Pd(CH3COO)2, PdCI2, Pd(CH3...... methyl methacrylate and/or methacrylic acid. Catalyst systems according to the invention are suitable for reactions forming separable product and catalyst phases and supported ionic liquid phase SILP applications....

Phospholipase A2 activity-dependent and -independent fusogenic activity of Naja nigricollis CMS-9 on zwitterionic and anionic phospholipid vesicles.

Science.gov (United States)

Chiou, Yi-Ling; Chen, Ying-Jung; Lin, Shinne-Ren; Chang, Long-Sen

2011-11-01

CMS-9, a phospholipase A(2) (PLA(2)) from Naja nigricollis venom, induced the death of human breast cancer MCF-7 cells accompanied with the formation of cell clumps without clear boundaries between cells. Annexin V-FITC staining indicated that abundant phosphatidylserine appeared on the outer membrane of MCF-7 cell clumps, implying the possibility that CMS-9 may promote membrane fusion via anionic phospholipids. To validate this proposition, fusogenic activity of CMS-9 on vesicles composed of zwitterionic phospholipid alone or a combination of zwitterionic and anionic phospholipids was examined. Although CMS-9-induced fusion of zwitterionic phospholipid vesicles depended on PLA(2) activity, CMS-9-induced fusion of vesicles containing anionic phospholipids could occur without the involvement of PLA(2) activity. Membrane-damaging activity of CMS-9 was associated with its fusogenicity. Moreover, CMS-9 induced differently membrane leakage and membrane fusion of vesicles with different compositions. Membrane fluidity and binding capability with phospholipid vesicles were not related to the fusogenicity of CMS-9. However, membrane-bound conformation and mode of CMS-9 depended on phospholipid compositions. Collectively, our data suggest that PLA(2) activity-dependent and -independent fusogenicity of CMS-9 are closely related to its membrane-bound modes and targeted membrane compositions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Cooperative Effects of Zwitterionic-Ionic Surfactant Mixtures on the Interfacial Water Structure Revealed by Sum Frequency Generation Vibrational Spectroscopy.

Science.gov (United States)

Pan, Xuecong; Yang, Fangyuan; Chen, Shunli; Zhu, Xuefeng; Wang, Chuanyi

2018-05-08

Cooperative effects of a series of equimolar binary zwitterionic-ionic surfactant mixtures on the interfacial water structure at the air-water interfaces have been studied by sum frequency generation vibrational spectroscopy (SFG-VS). For zwitterionic surfactant palmityl sulfobetaine (SNC 16 ), anionic surfactant sodium hexadecyl sulfate (SHS), and cationic surfactant cetyltrimethylammonium bromide (CTAB) with the same length of alkyl chain, significantly enhanced ordering of interfacial water molecules was observed for the zwitterionic-anionic surfactant mixtures SNC 16 -SHS, indicating that SNC 16 interacts more strongly with SHS than with CTAB because of the strong headgroup-headgroup electrostatic attraction for SNC 16 -SHS. Meanwhile, the SFG amplitude ratio of methyl and methylene symmetric stretching modes was used to verify the stronger interaction between SNC 16 and SHS. The conformational order indicator increased from 0.64 for SNC 16 to 7.17 for SNC 16 -SHS but only 0.94 for SNC 16 -CTAB. In addition, another anionic surfactant sodium dodecyl sulfate (SDS) was introduced to study the influence of chain-chain interaction. Decreased SFG amplitude of interfacial water molecules for SNC 16 -SDS was observed. Therefore, both the headgroup-headgroup electrostatic interaction and chain-chain van der Waals attractive interaction of the surfactants play an important role in enhancing the ordering of interfacial water molecules. The results provided experimental and theoretical bases for practical applications of the surfactants.

The crystal structure of zwitterionic 2-{[(4-iminiumyl-3-methyl-1,4-dihydropyridin-1-ylmethyl]carbamoyl}benzoate hemihydrate

Directory of Open Access Journals (Sweden)

C. S. Chidan Kumar

2017-07-01

Full Text Available The asymmetric unit of the title compound, C15H15N3O3·0.5H2O, comprises two 2-{[(4-iminiumyl-3-methyl-1,4-dihydropyridin-1-ylmethyl]carbamoyl}benzoate zwitterions (A and B and a water molecule. The dihedral angles between the pyridine and phenyl rings in the zwitterions are 53.69 (10 and 73.56 (11° in A and B, respectively. In the crystal, molecules are linked by N—H...O, O—H...O, C—H...O and C—H...π(ring hydrogen bonds into a three-dimensional network. The crystal structure also features π–π interactions involving the centroids of the pyridine and phenyl rings [centroid–centroid distances = 3.5618 (12 Å in A and 3.8182 (14 Å in B].

Chemical equilibrium. [maximizing entropy of gas system to derive relations between thermodynamic variables

Science.gov (United States)

1976-01-01

The entropy of a gas system with the number of particles subject to external control is maximized to derive relations between the thermodynamic variables that obtain at equilibrium. These relations are described in terms of the chemical potential, defined as equivalent partial derivatives of entropy, energy, enthalpy, free energy, or free enthalpy. At equilibrium, the change in total chemical potential must vanish. This fact is used to derive the equilibrium constants for chemical reactions in terms of the partition functions of the species involved in the reaction. Thus the equilibrium constants can be determined accurately, just as other thermodynamic properties, from a knowledge of the energy levels and degeneracies for the gas species involved. These equilibrium constants permit one to calculate the equilibrium concentrations or partial pressures of chemically reacting species that occur in gas mixtures at any given condition of pressure and temperature or volume and temperature.

Preparation of PES ultrafiltration membranes with natural amino acids based zwitterionic antifouling surfaces

International Nuclear Information System (INIS)

Xu, Chen; Liu, Xiaojiu; Xie, Binbin; Yao, Chen; Hu, Wenhan; Li, Yi; Li, Xinsong

2016-01-01

Highlights: • Amino acids have been successfully grafted onto the surface of PES membranes via amino groups induced epoxy ring opening. • Zwitterionic PES ultrafiltration membranes exhibit excellent antifouling performance and improved permeation properties. • A facile strategy to combat fouling of PES ultrafiltration membranes is developed by grafting natural amino acids. - Abstract: In this report, a simple and facile approach to enhance the antifouling property of poly(ether sulfone) (PES) ultrafiltration membrane was developed by grafting natural amino acids onto surface. First of all, poly(ether sulfone) composite membranes blended with poly(glycidyl methacrylate) were fabricated by phase inversion method followed by grafting of different types of natural amino acids onto the membrane surface through epoxy ring opening reaction. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR) and X-ray photoelectron spectroscopy (XPS) verified the substantial enrichment of amino acids onto the surface of PES membranes. The hydrophilicity of the PES membranes was improved after grafting amino acids. The mechanical property and morphologies of the PES membranes proved that their basic performances were not obviously affected by grafting reaction, and these parameters were all still in the typical range for ultrafiltration membranes. The antifouling property of the grafted PES membranes against bovine serum albumin (BSA) and lysozyme (Lyz) was investigated in detail. It was found that PES membranes incorporated with neutral amino acids exhibited higher fouling resistance to both BSA and Lyz than the parent PES membrane. It can be ascribed to the formation of zwitterionic structure on the surface consisting of protonated secondary amino cations and carboxyl anions. Meanwhile, PES membranes grafted with charged amino acids had better antifouling properties against protein with same electric charges and improved adsorption

Preparation of PES ultrafiltration membranes with natural amino acids based zwitterionic antifouling surfaces

Energy Technology Data Exchange (ETDEWEB)

Xu, Chen; Liu, Xiaojiu; Xie, Binbin; Yao, Chen [School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189 (China); Hu, Wenhan; Li, Yi [Suzhou Faith & Hope Membrane Technology Co., Ltd., Suzhou, 215000 (China); Li, Xinsong, E-mail: lixs@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189 (China)

2016-11-01

Highlights: • Amino acids have been successfully grafted onto the surface of PES membranes via amino groups induced epoxy ring opening. • Zwitterionic PES ultrafiltration membranes exhibit excellent antifouling performance and improved permeation properties. • A facile strategy to combat fouling of PES ultrafiltration membranes is developed by grafting natural amino acids. - Abstract: In this report, a simple and facile approach to enhance the antifouling property of poly(ether sulfone) (PES) ultrafiltration membrane was developed by grafting natural amino acids onto surface. First of all, poly(ether sulfone) composite membranes blended with poly(glycidyl methacrylate) were fabricated by phase inversion method followed by grafting of different types of natural amino acids onto the membrane surface through epoxy ring opening reaction. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR) and X-ray photoelectron spectroscopy (XPS) verified the substantial enrichment of amino acids onto the surface of PES membranes. The hydrophilicity of the PES membranes was improved after grafting amino acids. The mechanical property and morphologies of the PES membranes proved that their basic performances were not obviously affected by grafting reaction, and these parameters were all still in the typical range for ultrafiltration membranes. The antifouling property of the grafted PES membranes against bovine serum albumin (BSA) and lysozyme (Lyz) was investigated in detail. It was found that PES membranes incorporated with neutral amino acids exhibited higher fouling resistance to both BSA and Lyz than the parent PES membrane. It can be ascribed to the formation of zwitterionic structure on the surface consisting of protonated secondary amino cations and carboxyl anions. Meanwhile, PES membranes grafted with charged amino acids had better antifouling properties against protein with same electric charges and improved adsorption

Dye sensitized photovoltaic cells: Attaching conjugated polymers to zwitterionic ruthenium dyes

DEFF Research Database (Denmark)

Krebs, Frederik C; Biancardo, M.

2006-01-01

The synthesis of a zwitterionic ruthenium dye that binds to anatase surfaces and has a built-in functionality that allows for the attachment of a conjugated polymer chain is presented. The system was found to adsorb on the surface of anatase anchored by the ruthenium dye. Two types of devices were...... prepared: standard photoelectrochemical (PEC) solar cells and polymer solar cells. The PEC solar cells employed a sandwich geometry between TiO2 nanoporous photoanodes and Pt counter electrodes using LiI/I-2 in CH3CN as an electrolyte. The polymer solar cells employed planar anatase electrodes...

Evaluation of an ODS column modified with zwitterionic/nonionic mixed surfactants and its application to direct injection determination of inorganic anions.

Science.gov (United States)

Hasegawa, Takuya; Umemura, Tomonari; Koide, Akira; Chiba, Koichi; Ueki, Yuji; Tsunoda, Kin-ichi; Haraguchi, Hiroki

2005-08-01

An octadecylsilica (ODS) column modified with zwitterionic/nonionic mixed surfactants was evaluated for the direct injection determination of inorganic anions in biological fluids by ion chromatography. A zwitterionic surfactant (sulfobetaine-type) and a nonionic surfactant (polyoxyethylene-type) were used for a stationary-phase modification. When aqueous electrolyte solutions with concentrations of sub-mM to several mM were used as a mobile phase, the zwitterionic surfactant coated on the ODS surface exhibited unique separation selectivity for ionic species, while the nonionic surfactant coated on the ODS might have formed a hydrophilic network over the ODS surface and restricted matrix proteins from adsorbing on the stationary phase. Consequently, the mixed surfactant-modified column system allowed an efficient ion chromatographic separation of inorganic anions as well as a size-exclusive removal of column-fouling proteins. This separation system was applied to the direct injection determination of UV-absorbing anions in human saliva. The detection limits for nitrite, nitrate, iodide and thiocyanate were 3.1, 2.7, 4.5 and 25 microM, respectively, with UV detection at 210 nm (injection volume; 20 microl), and their relative standard deviations for 5 replicate measurements of saliva samples spiked with 100 microM each of those anions were 1.4, 0.9, 2.2 and 5.5%, respectively.

Biorefineries for the production of top building block chemicals and their derivatives.

Science.gov (United States)

Choi, Sol; Song, Chan Woo; Shin, Jae Ho; Lee, Sang Yup

2015-03-01

Due to the growing concerns on the climate change and sustainability on petrochemical resources, DOE selected and announced the bio-based top 12 building blocks and discussed the needs for developing biorefinery technologies to replace the current petroleum based industry in 2004. Over the last 10 years after its announcement, many studies have been performed for the development of efficient technologies for the bio-based production of these chemicals and derivatives. Now, ten chemicals among these top 12 chemicals, excluding the l-aspartic acid and 3-hydroxybutyrolactone, have already been commercialized or are close to commercialization. In this paper, we review the current status of biorefinery development for the production of these platform chemicals and their derivatives. In addition, current technological advances on industrial strain development for the production of platform chemicals using micro-organisms will be covered in detail with case studies on succinic acid and 3-hydroxypropionic acid as examples. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

On the structure and dynamics of water associated with single-supported zwitterionic and anionic membranes

DEFF Research Database (Denmark)

Miskowiec, A.; Buck, Z. N.; Hansen, Flemming Yssing

2017-01-01

We have used high-resolution quasielastic neutron scattering (QENS) to investigate the dynamics of water molecules (time scale of motion similar to ∼10-11- 10-9 s) in proximity to single-supported bilayers of the zwitterionic lipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphorylcholine) and the ani......We have used high-resolution quasielastic neutron scattering (QENS) to investigate the dynamics of water molecules (time scale of motion similar to ∼10-11- 10-9 s) in proximity to single-supported bilayers of the zwitterionic lipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphorylcholine......) and the anionic lipid DMPG (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol) in the temperature range 160-295 K. For both membranes, the temperature dependence of the intensity of neutrons scattered elastically and incoherently from these samples indicates a series of freezing/melting transitions...... the membrane and two types of confined water in closer proximity to the lipids. Specifically, we propose a water type termed "confined 2" located within and just above the lipid head groups of the membrane and confined 1 water that lies between the bulk-like and confined 2 water. Confined 1 water is only...

Determination of acid-base dissociation constants of very weak zwitterionic heterocyclic bases by capillary zone electrophoresis

Czech Academy of Sciences Publication Activity Database

Ehala, Sille; Grishina, Anastasia; Sheshenev, Andrey; Lyapkalo, Ilya; Kašička, Václav

2010-01-01

Roč. 1217, - (2010), s. 8048-8053 ISSN 0021-9673 R&D Projects: GA ČR(CZ) GA203/08/1428; GA ČR(CZ) GA203/09/0675 Institutional research plan: CEZ:AV0Z40550506 Keywords : acidity constant * capillary zone electrophoresis * zwitterionic heterocyclic bases Subject RIV: CC - Organic Chemistry Impact factor: 4.194, year: 2010

Effects of anions on the zwitterion stability of Glu, His and Arg investigated by IRMPD spectroscopy and theory

NARCIS (Netherlands)

O'Brien, J.T.; Prell, J.S.; Berden, G.; Oomens, J.; Williams, E.R.

2010-01-01

Interactions of halide anions (Cl-, Br-, and I-) with glutamic acid (Glu), histidine (His), and arginine (Arg) and their effects on stabilizing the zwitterionic form of these amino acids were investigated using infrared multiple photon dissociation (IRMPD) spectroscopy between 850 and 1900 cm(-1)

Water swelling, brine soluble imidazole based zwitterionic polymers-synthesis and study of reversible UCST behaviour and gel-sol transitions

NARCIS (Netherlands)

Vasantha, Vivek Arjunan; Jana, Satyasankar; Parthiban, Anbanandam; Vancso, Julius G.

2014-01-01

New vinylbenzene substituted imidazole based zwitterionic polymers with unique characteristics like swelling in water and solubility in concentrated brine solution in which they exhibited a reversible upper critical solution temperature (UCST) and gel-sol transitions are reported herein. © 2014 The

Exploration of zwitterionic cellulose acetate antifouling ultrafiltration membrane for bovine serum albumin (BSA) separation.

Science.gov (United States)

Liu, Yang; Huang, Haitao; Huo, Pengfei; Gu, Jiyou

2017-06-01

This study focused on the preparation of a new kind of membrane material, zwitterionic cellulose acetate (ZCA), via a three-step procedure consist of oxidization, Schiff base and quaternary amination reaction, and the fabrication of antifouling ZCA ultrafiltration membrane by the non-solvent-induced phase separation method (NIPS). The morphologies, surface chemical structures and compositions of the obtained CA and ZCA membranes were thoroughly characterized by field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Meanwhile, the thermal stability, porosity and average pore size of two investigated membranes were also studied. As a result, the ZCA membrane displayed significantly improved hydrophilicity and water permeability compared with those of the reference CA membrane, despite a slight decrease in the protein rejection ratio. According to the cycle ultrafiltration performance of bovine serum albumin (BSA) solution and protein adsorption experiment, ZCA membrane exhibited better flux recovery property and fouling resistant ability, especially irreversible fouling resistant ability, suggesting superior antifouling performance. This new approach gives polymer-based membrane a long time life and excellent ultrafiltration performance, and seems promising for potential applications in the protein separation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recovery and redispersion of gold nanoparticles using the self-assembly of a pH sensitive zwitterionic amphiphile.

Science.gov (United States)

Morita-Imura, Clara; Imura, Yoshiro; Kawai, Takeshi; Shindo, Hitoshi

2014-11-04

The pH-responsive self-assembly of zwitterionic amphiphile C16CA was expanded to the recovery of gold (Au) nanoparticles for environmentally friendly chemistry applications. Multilayered lamellae at pH ∼ 4 were successfully incorporated into nanoparticles by dispersion. Redispersion of nanoparticles was achieved under basic conditions by the transition of self-assembly.

Molecular structure, electronic properties, NLO, NBO analysis and spectroscopic characterization of Gabapentin with experimental (FT-IR and FT-Raman) techniques and quantum chemical calculations

Science.gov (United States)

Sinha, Leena; Karabacak, Mehmet; Narayan, V.; Cinar, Mehmet; Prasad, Onkar

2013-05-01

Gabapentin (GP), structurally related to the neurotransmitter GABA (gamma-aminobutyric acid), mimics the activity of GABA and is also widely used in neurology for the treatment of peripheral neuropathic pain. It exists in zwitterionic form in solid state. The present communication deals with the quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of GP using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. In view of the fact that amino acids exist as zwitterions as well as in the neutral form depending on the environment (solvent, pH, etc.), molecular properties of both the zwitterionic and neutral form of GP have been analyzed. The fundamental vibrational wavenumbers as well as their intensities were calculated and compared with experimental FT-IR and FT-Raman spectra. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The electric dipole moment, polarizability and the first hyperpolarizability values of the GP have been calculated at the same level of theory and basis set. The nonlinear optical (NLO) behavior of zwitterionic and neutral form has been compared. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet-visible (UV-Vis) spectrum of the title molecule has also been calculated using TD-DFT method. The thermodynamic properties of both the zwitterionic and neutral form of GP at different temperatures have been calculated.

Utilization of chemical derivatives in activation analysis

International Nuclear Information System (INIS)

Ehmann, W.D.

1990-01-01

Derivative activation analysis (DAA) is a method to enhance the sensitivity of nuclear activation analysis for the more elusive elements. It may also allow a degree of chemical speciation for the element of interest. DAA uses a preirradiation chemical reaction on the sample to initiate the formation of, or an exchange with, a chemical complex which contains a surrogate element, M. As a result, the amount of the element or the chemical species to be determined, X, is now represented by measurement of the amount of the surrogate element, M, that is made part of, or released by the complex species. The surrogate element is selected for its superior properties for nuclear activation analysis and the absence of interference reaction in its final determination by instrumental neutron activation analysis (INAA) after some preconcentration or separation chemistry. Published DAA studies have been limited to neutron activation analysis. DAA can offer the analyst some important advantages. It can determine elements, functional groups, or chemical species which cannot be determined directly by INAA, fast neutron activation analysis (FNAA), prompt gamma neutron activation analysis (PGNAA), or charged particle activation analysis (CPAA) procedures. When compared with conventional RNAA, there are fewer precautions with respect to handling of intensely radioactive samples, since the chemistry is done before the irradiation. The preirradiation chemistry may also eliminate many interferences that might occur in INAA and, through use of an appropriate surrogate element, can place the analytical gamma-ray line in an interference-free region of the gamma-ray spectrum

Surface Design in Solid-State Dye Sensitized Solar Cells: Effects of Zwitterionic Co-adsorbents on Photovoltaic Performance

KAUST Repository

Wang, Mingkui

2009-07-10

In solid-state dye sensitized solar cells (SSDSCs) charge recombination at the dye-hole transporting material interface plays a critical role in the cell efficiency. For the first time we report on the influence of dipolar coadsorbents on the photovoltaic performance of sensitized hetero-junction solar cells. In the present study, we investigated the effect of two zwitterionic butyric acid derivatives differing only in the polar moiety attached to their common 4 carbon-chain acid, i.e., 4-guanidinobutyric acid (GBA) and 4-aminobutyric acid (ABA). These two molecules were implemented as coadsorbents in conjunction with Z907Na dye on the SSDSC. It was found that a Z907Na/GBA dye/co-adsorbent combination increases both the open circuit voltage (V oc) and short-circuit current density ( Jsc) as compared to using Z907Na dye alone. The Z907Na/ABA dye/co-adsorbent combination increases the Jsc. Impedance and transient photovoltage investigations elucidate the cause of these remarkable observations. ©2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Specific Binding on Antifouling Zwitterionic Polymer-Coated Microbeads as Measured by Flow Cytometry.

Science.gov (United States)

van Andel, Esther; de Bus, Ian; Tijhaar, Edwin J; Smulders, Maarten M J; Savelkoul, Huub F J; Zuilhof, Han

2017-11-08

Micron- and nano-sized particles are extensively used in various biomedical applications. However, their performance is often drastically hampered by the nonspecific adsorption of biomolecules, a process called biofouling, which can cause false-positive and false-negative outcomes in diagnostic tests. Although antifouling coatings have been extensively studied on flat surfaces, their use on micro- and nanoparticles remains largely unexplored, despite the widespread experimental (specifically, clinical) uncertainties that arise because of biofouling. Here, we describe the preparation of magnetic micron-sized beads coated with zwitterionic sulfobetaine polymer brushes that display strong antifouling characteristics. These coated beads can then be equipped with recognition elements of choice, to enable the specific binding of target molecules. First, we present a proof of principle with biotin-functionalized beads that are able to specifically bind fluorescently labeled streptavidin from a complex mixture of serum proteins. Moreover, we show the versatility of the method by demonstrating that it is also possible to functionalize the beads with mannose moieties to specifically bind the carbohydrate-binding protein concanavalin A. Flow cytometry was used to show that thus-modified beads only bind specifically targeted proteins, with minimal/near-zero nonspecific protein adsorption from other proteins that are present. These antifouling zwitterionic polymer-coated beads, therefore, provide a significant advancement for the many bead-based diagnostic and other biosensing applications that require stringent antifouling conditions.

Zwitterionization of glycine in water environment: Stabilization mechanism and NMR spectral signatures

Science.gov (United States)

Valverde, Danillo; da Costa Ludwig, Zélia Maria; da Costa, Célia Regina; Ludwig, Valdemir; Georg, Herbert C.

2018-01-01

At physiological conditions, myriads of biomolecules (e.g., amino acids, peptides, and proteins) exist predominantly in the zwitterionic structural form and their biological functions will result in these conditions. However these geometrical structures are inaccessible energetically in the gas phase, and at this point, stabilization of amino-acids in physiological conditions is still under debate. In this paper, the electronic properties of a glycine molecule in the liquid environment were studied by performing a relaxation of the glycine geometry in liquid water using the free energy gradient method combined with a sequential quantum mechanics/molecular mechanics approach. A series of Monte Carlo Metropolis simulations of the glycine molecule embedded in liquid water, followed by only a quantum mechanical calculation in each of them were carried out. Both the local and global liquid environments were emphasized to obtain nuclear magnetic resonance (NMR) parameters for the glycine molecule in liquid water. The results of the equilibrium structure in solution and the systematic study of the hydrogen bonds were used to discard the direct proton transfer from the carboxyl group to the ammonium group of the glycine molecule in water solution. The calculations of the Density Functional Theory (DFT) were performed to study the polarization of the solvent in the parameters of nuclear magnetic resonance of the glycine molecule in liquid water. DFT calculations predicted isotropic chemical changes on the H, C, N, and O atoms of glycine in liquid water solution which agree with the available experimental data.

Molecular dynamics investigation of the influence of anionic and zwitterionic interfaces on antimicrobial peptides' structure: implications for peptide toxicity and activity

DEFF Research Database (Denmark)

Khandelia, Himanshu; Kaznessis, Yiannis N

2006-01-01

Molecular dynamics simulations of three related helical antimicrobial peptides have been carried out in zwitterionic diphosphocholine (DPC) micelles and anionic sodiumdodecylsulfate (SDS) micelles. These systems can be considered as model mammalian and bacterial membrane interfaces, respectively...

Zwitterionic bis(phenolate)amine lanthanide complexes for the ring-opening polymerisation of cyclic esters

NARCIS (Netherlands)

Dyer, H.E.; Huijser, S.; Schwarz, A.D.; Wang, Chao; Duchateau, R.; Mountford, P.

2008-01-01

The reaction of Sm{N(SiMe3)2}3 with the bis(phenol)amines H2O2NR (H2O 2NR = RCH2CH2N(2-HO-3,5-C 6H2tBu2)2; R = OMe, NMe2 or Me) gave exclusively zwitterions Sm(O2N R)(HO2NR). For R = OMe or NMe2 these were efficient catalysts for the ring-opening polymerisation of e-caprolactone and d,l-lactide with

Molecular and Thermodynamic Properties of Zwitterions versus Ionic Liquids: A Comprehensive Computational Analysis to Develop Advanced Separation Processes.

Science.gov (United States)

Moreno, Daniel; Gonzalez-Miquel, Maria; Ferro, Victor R; Palomar, Jose

2018-04-05

Zwitterion ionic liquids (ZIs) are compounds in which both counterions are covalently tethered, conferring them with unique characteristics; however, most of their properties are still unknown, representing a bottleneck to exploit their practical applications. Herein, the molecular and fluid properties of ZIs and their mixtures were explored by means of quantum chemical analysis based on the density functional theory (DFT) and COSMO-RS method, and compared against homologous ionic liquids (ILs) to provide a comprehensive overview of the effect of the distinct structures on their physicochemical and thermodynamic behavior. Overall, ZIs were revealed as compounds with higher polarity and stronger hydrogen-bonding capacity, implying higher density, viscosity, melting point, and even lower volatility than structurally similar ILs. The phase equilibrium of binary and ternary systems supports stronger attractive interactions between ZIs and polar compounds, whereas higher liquid-liquid immiscibility with nonpolar compounds may be expected. Ultimately, the performance of ZIs in the wider context of separation processes is illustrated, while providing molecular insights to allow their selection and design for relevant applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mucoadhesive Polymer Hyaluronan as Biodegradable Cationic/Zwitterionic-Drug Delivery Vehicle

Directory of Open Access Journals (Sweden)

Francisco Torrens

2015-01-01

Full Text Available Mucoadhesive polymers in pharmaceutical formulations release drugs in mucosal areas. They interact and fix to mucus via molecular interpenetration, etc., which increase drug bioavailability. Polymers physicochemical properties affect formulation mucoadhesion, rheological behaviour and drug absorption. Hyaluronan (HA is selected as a mucoadhesive and biodegradable polymer. Geometric, topological and fractal analyses are carried out with program TOPO. Reference calculations are performed with algorithm GEPOL. Procedure TOPO underestimates molecular volume by 0.7%. Error results 5% in surface area and derived topological indices. Solvent-accessible surface is undercalculated by 3%: from hexamer HA to HA·3Ca and hydrate, the hydrophobic term rises by 42% and decays by 26%, and hydrophilic part drops by 14% and rises by 58% in agreement with the number of H-bonds. Accessibility rises by 9% and decays by 8%. Fractal dimension is underevaluated by 1% and for HA it results 1.566; on going to HA·3Ca and hydrate it rises by 2% and 1%. External-atoms dimension increases by 11%: for HA it results 1.725. When going to HA·3Ca and hydrate, it augments by 4% and 0.3%. On going from HA to HA·3Ca and hydrate, nonburied minus molecular dimension enlarges by 20% and decays by 9%. The hydrate globularity is lower than for water, Ca2+ and averages of O-atoms in HA. Ca2+ rugosity is smaller than for hydrate, averages of O-atoms in HA and water. Ca2+ and water accessibilities are greater than for hydrate. As cations exchange in HA·3Ca requires Ca2+ alteration, rises of drug zwitterionic character and acidic pH increase absorption.

Antimicrobial activity of chemically modified dextran derivatives.

Science.gov (United States)

Tuchilus, Cristina G; Nichifor, Marieta; Mocanu, Georgeta; Stanciu, Magdalena C

2017-04-01

Cationic amphiphilic dextran derivatives with a long alkyl group attached to the reductive end of the polysaccharide chain and quaternary ammonium groups attached as pendent groups to the main dextran backbone were synthesized and tested for their antimicrobial properties against several bacteria and fungi strains. Dependence of antimicrobial activity on both polymer chemical composition (dextran molar mass, length of end alkyl group and chemical structure of ammonium groups) and type of microbes was highlighted by disc-diffusion method (diameter of inhibition zone) and broth microdilution method (minimum inhibitory concentrations). Polymers had antimicrobial activity for all strains studied, except for Pseudomonas aeruginosa ATCC 27853. The best activity against Staphylococcus aureus (Minimun Inhibitory Concentration 60μg/mL) was provided by polymers obtained from dextran with lower molecular mass (Mn=4500), C 12 H 25 or C 18 H 37 end groups, and N,N-dimethyl-N-benzylammonium pendent groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Processes for converting biomass-derived feedstocks to chemicals and liquid fuels

Science.gov (United States)

Held, Andrew; Woods, Elizabeth; Cortright, Randy; Gray, Matthew

2018-04-17

The present invention provides processes, methods, and systems for converting biomass-derived feedstocks to liquid fuels and chemicals. The method generally includes the reaction of a hydrolysate from a biomass deconstruction process with hydrogen and a catalyst to produce a reaction product comprising one of more oxygenated compounds. The process also includes reacting the reaction product with a condensation catalyst to produce C.sub.4+ compounds useful as fuels and chemicals.

Processes for converting biomass-derived feedstocks to chemicals and liquid fuels

Science.gov (United States)

Held, Andrew; Woods, Elizabeth; Cortright, Randy; Gray, Matthew

2017-05-23

The present invention provides processes, methods, and systems for converting biomass-derived feedstocks to liquid fuels and chemicals. The method generally includes the reaction of a hydrolysate from a biomass deconstruction process with hydrogen and a catalyst to produce a reaction product comprising one of more oxygenated compounds. The process also includes reacting the reaction product with a condensation catalyst to produce C.sub.4+ compounds useful as fuels and chemicals.

Marine Derived Polysaccharides for Biomedical Applications: Chemical Modification Approaches

Directory of Open Access Journals (Sweden)

Paola Laurienzo

2008-09-01

Full Text Available Polysaccharide-based biomaterials are an emerging class in several biomedical fields such as tissue regeneration, particularly for cartilage, drug delivery devices and gelentrapment systems for the immobilization of cells. Important properties of the polysaccharides include controllable biological activity, biodegradability, and their ability to form hydrogels. Most of the polysaccharides used derive from natural sources; particularly, alginate and chitin, two polysaccharides which have an extensive history of use in medicine, pharmacy and basic sciences, and can be easily extracted from marine plants (algae kelp and crab shells, respectively. The recent rediscovery of poly-saccharidebased materials is also attributable to new synthetic routes for their chemical modification, with the aim of promoting new biological activities and/or to modify the final properties of the biomaterials for specific purposes. These synthetic strategies also involve the combination of polysaccharides with other polymers. A review of the more recent research in the field of chemical modification of alginate, chitin and its derivative chitosan is presented. Moreover, we report as case studies the results of our recent work concerning various different approaches and applications of polysaccharide-based biomaterials, such as the realization of novel composites based on calcium sulphate blended with alginate and with a chemically modified chitosan, the synthesis of novel alginate-poly(ethylene glycol copolymers and the development of a family of materials based on alginate and acrylic polymers of potential interest as drug delivery systems.

Applying thermosettable zwitterionic copolymers as general fouling-resistant and thermal-tolerant biomaterial interfaces.

Science.gov (United States)

Chou, Ying-Nien; Chang, Yung; Wen, Ten-Chin

2015-05-20

We introduced a thermosettable zwitterionic copolymer to design a high temperature tolerance biomaterial as a general antifouling polymer interface. The original synthetic fouling-resistant copolymer, poly(vinylpyrrolidone)-co-poly(sulfobetaine methacrylate) (poly(VP-co-SBMA)), is both thermal-tolerant and fouling-resistant, and the antifouling stability of copolymer coated interfaces can be effectively controlled by regulating the VP/SBMA composition ratio. We studied poly(VP-co-SBMA) copolymer gels and networks with a focus on their general resistance to protein, cell, and bacterial bioadhesion, as influenced by the thermosetting process. Interestingly, we found that the shape of the poly(VP-co-SBMA) copolymer material can be set at a high annealing temperature of 200 °C while maintaining good antifouling properties. However, while the zwitterionic PSBMA polymer gels were bioinert as expected, control of the fouling resistance of the PSBMA polymer networks was lost in the high temperature annealing process. A poly(VP-co-SBMA) copolymer network composed of PSBMA segments at 32 mol % showed reduced fibrinogen adsorption, tissue cell adhesion, and bacterial attachment, but a relatively higher PSBMA content of 61 mol % was required to optimize resistance to platelet adhesion and erythrocyte attachment to confer hemocompatibility to human blood. We suggest that poly(VP-co-SBMA) copolymers capable of retaining stable fouling resistance after high temperature shaping have a potential application as thermosettable materials in a bioinert interface for medical devices, such as the thermosettable coating on a stainless steel blood-compatible metal stent investigated in this study.

Application of a new bifunctionalized chitosan derivative with zwitterionic characteristics for the adsorption of Cu(2+), Co(2+), Ni(2+), and oxyanions of Cr(6+) from aqueous solutions: Kinetic and equilibrium aspects.

Science.gov (United States)

de Almeida, Francine Tatiane Rezende; Ferreira, Bruno Christiano Silva; Moreira, Ana Luísa da Silva Lage; de Freitas, Rossimiriam Pereira; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius Alves

2016-03-15

This study describes the synthesis of a new chitosan derivative (C2) with zwitterionic characteristics and its use for the removal of cationic species Cu(2+), Co(2+), and Ni(2+) and anionic species of Cr(6+) in a single aqueous solution. The new adsorbent was synthesized by quaternization of the amine group of chitosan and esterification of hydroxyl groups with EDTA dianhydride. These combined reactions gave both cationic and anionic characteristics to C2 with the release of quaternary ammonium groups and carboxylic groups. The capacity of C2 to adsorb Cu(2+), Co(2+), Ni(2+), and oxyanions of Cr(6+) was evaluated in a batch process with different contact times, pH values, and initial concentrations. Adsorption isotherms were best fitted to the Langmuir and Sips models. The maximum adsorption capacities (Q(max)) of C2 for adsorption of Cu(2+), Co(2+), Ni(2+), and Cr(6+) were 0.698, 1.125, 0.725, and 1.910 mmol/g, respectively. The Δ(ads)G° values were in the range from -20 to -28 kJ/mol. These values suggest a mixed mechanism controlling adsorption. Desorption studies using an aqueous solution consisting of 0.1 mol/L HNO3 were carried out. The reusability of the recovered C2 adsorbent after desorption was also evaluated. Copyright © 2015 Elsevier Inc. All rights reserved.

Halophilic polysulfabetaines-synthesis and study of gelation and thermoresponsive behavior

NARCIS (Netherlands)

Vasantha, Vivek Arjunan; Jana, Satyasankar; Parthiban, Anbanandam; Vancso, Julius G.

2014-01-01

Polysulfabetaines (PSBs) derived from zwitterionic sulfates (contrary to commonly used polysulfobetaines which are derived from zwitterionic sulfonates) were synthesized for the first time. PSBs dissolved in brine (halophilic), swelled in deionized water and also exhibited reversible and

Isolation of a Moderately Stable but Sensitive Zwitterionic Diazonium Tetrazolyl-1,2,3-triazolate.

Science.gov (United States)

Klapötke, Thomas M; Krumm, Burkhard; Pflüger, Carolin

2016-07-15

An unexpected formation of a diazonium compound was observed by nitration of an amino substituted triazolyl tetrazole with mixed acid. The crystal structure determination revealed a zwitterionic diazonium tetrazolyl-1,2,3-triazolate, whose constitution was supported by NMR and vibrational spectroscopic analysis. The thermal stability and sensitivity toward impact and friction were determined. In contrast, diazotriazoles are rather unstable and are mainly handled in solution and/or low temperatures, which is not the case for this diazonium tetrazolyl-1,2,3-triazolate, being stable at ambient temperature.

Interactions of a zwitterionic thiophene-based conjugated polymer with surfactants

DEFF Research Database (Denmark)

Costa, Telma; De Azevedo, Diego; Stewart, Beverly

2015-01-01

In this paper we investigate the optical and structural properties of a zwitterionic poly[3-(N-(4-sulfonato-1-butyl)-N,N-diethylammonium)hexyl-2,5-thiophene] (P3SBDEAHT) conjugated polyelectrolyte (CPE) and its interaction in water with surfactants, using absorption, photoluminescence (PL......), electrical conductivity, molecular dynamics simulations (MDS) and small-angle X-ray scattering (SAXS). Different surfactants were studied to evaluate the effect of the head group and chain length on the self-assembly. PL data emphasize the importance of polymer-surfactant electrostatic interactions...... in the formation of complexes. Nevertheless, conductivity and MDS data have shown that nonspecific interactions also play an important role. These seem to be responsible for the spatial position of the surfactant tail in the complex and, eventually, for breaking-up P3SBDEAHT aggregates. SAXS measurements on P3...

Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

Science.gov (United States)

Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

2015-06-15

Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. Copyright © 2015 Elsevier Inc. All rights reserved.

Palladium catalyst system comprising zwitterion and/or acid-functionalized ionic liquid

DEFF Research Database (Denmark)

2011-01-01

The present invention concerns a catalyst system in particular a catalyst system comprising Palladium (Pd), a zwitterion and/or an acid-functionalized ionic liquid, and one or more phosphine ligands, wherein the Pd catalyst can be provided by a complex precursor, such as Pd(CH3COO)2, PdCI2, Pd(CH3......COCHCOCH3), Pd (CF3COO)2, Pd(PPh3)4 or Pd2(dibenzylideneacetone)3. Such catalyst systems can be used for e.g. alkoxycarbonylation reactions, carboxylation reactions, and/or in a co-polymerization reaction, e.g. in the production of methyl propionate and/or propanoic acid, optionally in processes forming...... methyl methacrylate and/or methacrylic acid. Catalyst systems according to the invention are suitable for reactions forming separable product and catalyst phases and supported ionic liquid phase SILP applications....

Enhancing the specificity of polymerase chain reaction by graphene oxide through surface modification: zwitterionic polymer is superior to other polymers with different charges

Science.gov (United States)

Zhong, Yong; Huang, Lihong; Zhang, Zhisen; Xiong, Yunjing; Sun, Liping; Weng, Jian

2016-01-01

Graphene oxides (GOs) with different surface characteristics, such as size, reduction degree and charge, are prepared, and their effects on the specificity of polymerase chain reaction (PCR) are investigated. In this study, we demonstrate that GO with a large size and high reduction degree is superior to small and nonreduced GO in enhancing the specificity of PCR. Negatively charged polyacrylic acid (PAA), positively charged polyacrylamide (PAM), neutral polyethylene glycol (PEG) and zwitterionic polymer poly(sulfobetaine) (pSB) are used to modify GO. The PCR specificity-enhancing ability increases in the following order: GO-PAA Pfu DNA polymerase. Our data demonstrate that the size, reduction degree and surface charge of GO affect the specificity of PCR. Based on our results, zwitterionic polymer-modified GO may be used as an efficient additive for enhancing the specificity of PCR. PMID:27956830

Synthesis and Solution Properties of Zwitterionic Copolymer of Acrylamide with 3-[(2-Acrylamido)dimethylammonio]propanesulfonate

Energy Technology Data Exchange (ETDEWEB)

Xiao, Hui; Hu, Jing; Jin, Shuailin; Li, Rui Hai [Sichuan Univ., Chengdu (China)

2013-09-15

A novel zwitterionic monomer 3-[(2-acrylamido)dimethylammonio]propanesulfonate (DMADAS) was designed and synthesized in this study. Then it was polymerized with acrylamide (AM) by free radical polymerization in 0.5 mol/L NaCl solution with ammonium persulfate ((NH{sub 4}){sub 2}S{sub 2}O{sub 8}) and sodium sulfate (NaHSO{sub 3}) as initiator. The structure and composition of DMADAS and acrylamide-3-[(2-acrylamido)-dimethylammonio]propanesulfonate copolymer (P-AM-DMADAS) were characterized by FT-IR spectroscopy, {sup 1}H NMR and elemental analyses. Isoelectric point (IEP) of P-AM-DMADAS was tested by nanoparticle size and potential analyzer. Solution properties of copolymer were studied by reduced viscosity. Antipolyelectrolyte behavior was observed and was found to be enhanced with increasing DMADAS content in copolymer. The results showed that the viscosity of P-AM-DMADAS is 5.472 dl/g in pure water. Electrolyte was added, which weakened the mutual attraction between sulfonic acid group and quaternary ammonium group. The conformation became loose, which led to the increase of reduced viscosity. The ability of monovalent and divalent cation influencing the viscosity of zwitterionic copolymer obeyed the following sequence: Li{sup +} < Na{sup +} < K{sup +}, Mg{sup 2+} < Ca{sup 2+} < Ba{sup 2+}, and that of anion is in the order: Cl{sup -} < Br{sup -} < I{sup -}, CO{sub 3}{sup 2-} > SO{sub 3}{sup 2-} ≅ SO{sub 4}{sup 2-}.

Zwitterionic sulfobetaine-grafted poly(vinylidene fluoride) membrane surface with stably anti-protein-fouling performance via a two-step surface polymerization

Energy Technology Data Exchange (ETDEWEB)

Li Qian; Bi Qiuyan; Zhou Bo [Membrane Technology and Engineering Research Center, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Wang Xiaolin, E-mail: xl-wang@tsinghua.edu.cn [Membrane Technology and Engineering Research Center, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2012-03-01

A zwitterionic polymer, poly(3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (poly(MPDSAH)) was successfully grafted in high density from the surface of poly(vinylidene fluoride) (PVDF) hollow fiber membrane via a two-step polymerization. Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) chains were firstly grafted from outside surface of PVDF membrane through atom transfer radical polymerization (ATRP) to provide the initiation sites for subsequent cerium (Ce (IV))-induced graft copolymerization of polyMPDSAH in the presence of N,N Prime -ethylene bisacrylamide (EBAA) as a cross-linking agent. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) confirmed that the EBAA could stimulate zwitterionic polymers grafting onto the membrane surface. The dense poly(MPDSAH) layers on the PVDF membrane surface were revealed by the scanning electron microscope (SEM). The mechanical property of PVDF membrane was improved by the zwitterionic surface layers. The gravimetry results indicated the grafting amount increased to 520 {mu}g/cm{sup 2} for a copolymerization time of more than 3 h. Static and dynamic water contact angle measurements showed that the surface hydrophilicity of the PVDF membranes was significantly enhanced. As the grafting amount reached 513 {mu}g cm{sup -2}, the value of contact angle dropped to 22.1 Degree-Sign and the amount of protein adsorption decreased to zero. The cyclic experiments for BSA solution filtration demonstrated that the extent of protein fouling was significantly reduced and most of the fouling was reversible. The grafted polymer layer on the PVDF membrane showed a good stability during the membrane cleaning process. The experimental results concluded a good prospect in obtaining the sulfobetaine-modified PVDF membranes with high mechanical strength, good anti-protein-fouling performance, and long-term stability via the two-step polymerization.

Zwitterionic sulfobetaine-grafted poly(vinylidene fluoride) membrane surface with stably anti-protein-fouling performance via a two-step surface polymerization

International Nuclear Information System (INIS)

Li Qian; Bi Qiuyan; Zhou Bo; Wang Xiaolin

2012-01-01

A zwitterionic polymer, poly(3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (poly(MPDSAH)) was successfully grafted in high density from the surface of poly(vinylidene fluoride) (PVDF) hollow fiber membrane via a two-step polymerization. Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) chains were firstly grafted from outside surface of PVDF membrane through atom transfer radical polymerization (ATRP) to provide the initiation sites for subsequent cerium (Ce (IV))-induced graft copolymerization of polyMPDSAH in the presence of N,N′-ethylene bisacrylamide (EBAA) as a cross-linking agent. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) confirmed that the EBAA could stimulate zwitterionic polymers grafting onto the membrane surface. The dense poly(MPDSAH) layers on the PVDF membrane surface were revealed by the scanning electron microscope (SEM). The mechanical property of PVDF membrane was improved by the zwitterionic surface layers. The gravimetry results indicated the grafting amount increased to 520 μg/cm 2 for a copolymerization time of more than 3 h. Static and dynamic water contact angle measurements showed that the surface hydrophilicity of the PVDF membranes was significantly enhanced. As the grafting amount reached 513 μg cm -2 , the value of contact angle dropped to 22.1° and the amount of protein adsorption decreased to zero. The cyclic experiments for BSA solution filtration demonstrated that the extent of protein fouling was significantly reduced and most of the fouling was reversible. The grafted polymer layer on the PVDF membrane showed a good stability during the membrane cleaning process. The experimental results concluded a good prospect in obtaining the sulfobetaine-modified PVDF membranes with high mechanical strength, good anti-protein-fouling performance, and long-term stability via the two-step polymerization.

Dicationic and zwitterionic catalysts for the amine-initiated, immortal ring-opening polymerisation of rac-lactide: facile synthesis of amine-terminated, highly heterotactic PLA

NARCIS (Netherlands)

Clark, L.; Cushion, M.G.; Dyer, H.E.; Schwarz, A.D.; Duchateau, R.; Mountford, P.

2010-01-01

Dicationic, zwitterionic and conventional yttrium compounds act as catalysts for the primary or secondary amine-initiated immortal ROP of rac-lactide; amine-terminated, highly heterotactic poly(rac-lactides) with narrow polydispersities and well-controlled molecular weights are prepared in this

Structural analysis of zwitterionic liquids vs. homologous ionic liquids

Science.gov (United States)

Wu, Boning; Kuroda, Kosuke; Takahashi, Kenji; Castner, Edward W.

2018-05-01

Zwitterionic liquids (Zw-ILs) have been developed that are homologous to monovalent ionic liquids (ILs) and show great promise for controlled dissolution of cellulosic biomass. Using both high energy X-ray scattering and atomistic molecular simulations, this article compares the bulk liquid structural properties for novel Zw-ILs with their homologous ILs. It is shown that the significant localization of the charges on Zw-ILs leads to charge ordering similar to that observed for conventional ionic liquids with monovalent anions and cations. A low-intensity first sharp diffraction peak in the liquid structure factor S(q) is observed for both the Zw-IL and the IL. This is unexpected since both the Zw-IL and IL have a 2-(2-methoxyethoxy)ethyl (diether) functional group on the cationic imidazolium ring and ether functional groups are known to suppress this peak. Detailed analyses show that this intermediate range order in the liquid structure arises for slightly different reasons in the Zw-IL vs. the IL. For the Zw-IL, the ether tails in the liquid are shown to aggregate into nanoscale domains.

Hydrophobic radical influence on structure and vibration spectra of zwitter-ionic forms of glycine and alanine in condensed state

International Nuclear Information System (INIS)

Ten, G.N.; Kadrov, D.M.; Baranov, V.I.

2014-01-01

Structure and vibrational spectra of the zwitter-ionic forms of glycine and alanine in water solution and solid state have been calculated in the B3LYP/6-311++G(d,p) approximation. The environment influence has been taken into account by two methods: the self-consistent reaction field (SCRF) method and one of modeling the glycine and alanine complexes with molecules of water. The structure, energy and spectral properties have been determined which allow establishing an influence of the hydrophobic radical on the glycine and alanine ability to form the hydrogen bonds. It is shown by comparison with experiment that for the calculation of vibrational (IR and Raman) spectra of the zwitter-ionic forms of glycine and alanine in the condensed states they must be surrounded with three molecules of water, one of which is located between the N + H 3 and COO - ionic groups. The value of energy necessary to form the Ala complexes with water compared to Gly ones is 56.47 and 12.55 kcal/mol higher in the case of the complex formation with 1and 3 molecules of water, respectively, located between bipolar groups. (authors)

Anharmonic effects in IR, Raman, and Raman optical activity spectra of alanine and proline zwitterions.

Science.gov (United States)

Danecek, Petr; Kapitán, Josef; Baumruk, Vladimír; Bednárová, Lucie; Kopecký, Vladimír; Bour, Petr

2007-06-14

The difference spectroscopy of the Raman optical activity (ROA) provides extended information about molecular structure. However, interpretation of the spectra is based on complex and often inaccurate simulations. Previously, the authors attempted to make the calculations more robust by including the solvent and exploring the role of molecular flexibility for alanine and proline zwitterions. In the current study, they analyze the IR, Raman, and ROA spectra of these molecules with the emphasis on the force field modeling. Vibrational harmonic frequencies obtained with 25 ab initio methods are compared to experimental band positions. The role of anharmonic terms in the potential and intensity tensors is also systematically explored using the vibrational self-consistent field, vibrational configuration interaction (VCI), and degeneracy-corrected perturbation calculations. The harmonic approach appeared satisfactory for most of the lower-wavelength (200-1800 cm(-1)) vibrations. Modern generalized gradient approximation and hybrid density functionals, such as the common B3LYP method, provided a very good statistical agreement with the experiment. Although the inclusion of the anharmonic corrections still did not lead to complete agreement between the simulations and the experiment, occasional enhancements were achieved across the entire region of wave numbers. Not only the transitional frequencies of the C-H stretching modes were significantly improved but also Raman and ROA spectral profiles including N-H and C-H lower-frequency bending modes were more realistic after application of the VCI correction. A limited Boltzmann averaging for the lowest-frequency modes that could not be included directly in the anharmonic calculus provided a realistic inhomogeneous band broadening. The anharmonic parts of the intensity tensors (second dipole and polarizability derivatives) were found less important for the entire spectral profiles than the force field anharmonicities (third

Poly(zwitterionic)protein conjugates offer increased stability without sacrificing binding affinity or bioactivity

Science.gov (United States)

Keefe, Andrew J.; Jiang, Shaoyi

2012-01-01

Treatment with therapeutic proteins is an attractive approach to targeting a number of challenging diseases. Unfortunately, the native proteins themselves are often unstable in physiological conditions, reducing bioavailability and therefore increasing the dose that is required. Conjugation with poly(ethylene glycol) (PEG) is often used to increase stability, but this has a detrimental effect on bioactivity. Here, we introduce conjugation with zwitterionic polymers such as poly(carboxybetaine). We show that poly(carboxybetaine) conjugation improves stability in a manner similar to PEGylation, but that the new conjugates retain or even improve the binding affinity as a result of enhanced protein-substrate hydrophobic interactions. This chemistry opens a new avenue for the development of protein therapeutics by avoiding the need to compromise between stability and affinity.

Continuous-Flow Processes in Heterogeneously Catalyzed Transformations of Biomass Derivatives into Fuels and Chemicals

Directory of Open Access Journals (Sweden)

Antonio A. Romero

2012-07-01

Full Text Available Continuous flow chemical processes offer several advantages as compared to batch chemistries. These are particularly relevant in the case of heterogeneously catalyzed transformations of biomass-derived platform molecules into valuable chemicals and fuels. This work is aimed to provide an overview of key continuous flow processes developed to date dealing with a series of transformations of platform chemicals including alcohols, furanics, organic acids and polyols using a wide range of heterogeneous catalysts based on supported metals, solid acids and bifunctional (metal + acidic materials.

Biomass-derived Syngas Utilization for Fuels and Chemicals - Final Report

Energy Technology Data Exchange (ETDEWEB)

Dayton, David C

2010-03-24

. Task 3: Chemical Synthesis: Promising process routes will be identified for synthesis of selected chemicals from biomass-derived syngas. A project milestone was to select promising mixed alcohol catalysts and screen productivity and performance in a fixed bed micro-reactor using bottled syngas. This milestone was successfully completed in collaboration withour catalyst development partner. Task 4: Modeling, Engineering Evaluation, and Commercial Assessment: Mass and energy balances of conceptual commercial embodiment for FT and chemical synthesis were completed.

Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

Science.gov (United States)

Sun, Hong; Gao, Shushan; Li, Xiaoming; Li, Chunshun; Wang, Bingui

2013-03-01

A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192, an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa, resulted in the isolation of nine known secondary metabolites, including four indole-diterpenoids: penijanthine A ( 1), paspaline ( 2), paspalinine ( 3), and penitrem A ( 4); three tricycloalternarene derivatives: tricycloalternarene 3a ( 5), tricycloalternarene 1b ( 6), and tricycloalternarene 2b ( 7); and two alternariol congeners: djalonensone ( 8) and alternariol ( 9). The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature. The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum, with inhibition zone diameters of 8 and 9 mm, respectively, at 100 μg/disk. To the best of our knowledge, this is the first report on the secondary metabolites of mangrove-derived A lternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus A lternaria.

Detergent extraction of herpes simplex virus type 1 glycoprotein D by zwitterionic and non-ionic detergents and purification by ion-exchange high-performance liquid chromatography

NARCIS (Netherlands)

Welling-Wester, S; Feijlbrief, M; Koedijk, DGAM; Welling, GW

1998-01-01

Detergents (surfactants) are the key reagents in the extraction and purification of integral membrane proteins. Zwitterionic and non-ionic detergents were used for the extraction of recombinant glycoprotein D (gD-1) of herpes simplex virus type 1 (HSV-1) from insect cells infected with recombinant

Prediction of pKa Values for Druglike Molecules Using Semiempirical Quantum Chemical Methods.

Science.gov (United States)

Jensen, Jan H; Swain, Christopher J; Olsen, Lars

2017-01-26

Rapid yet accurate pK a prediction for druglike molecules is a key challenge in computational chemistry. This study uses PM6-DH+/COSMO, PM6/COSMO, PM7/COSMO, PM3/COSMO, AM1/COSMO, PM3/SMD, AM1/SMD, and DFTB3/SMD to predict the pK a values of 53 amine groups in 48 druglike compounds. The approach uses an isodesmic reaction where the pK a value is computed relative to a chemically related reference compound for which the pK a value has been measured experimentally or estimated using a standard empirical approach. The AM1- and PM3-based methods perform best with RMSE values of 1.4-1.6 pH units that have uncertainties of ±0.2-0.3 pH units, which make them statistically equivalent. However, for all but PM3/SMD and AM1/SMD the RMSEs are dominated by a single outlier, cefadroxil, caused by proton transfer in the zwitterionic protonation state. If this outlier is removed, the RMSE values for PM3/COSMO and AM1/COSMO drop to 1.0 ± 0.2 and 1.1 ± 0.3, whereas PM3/SMD and AM1/SMD remain at 1.5 ± 0.3 and 1.6 ± 0.3/0.4 pH units, making the COSMO-based predictions statistically better than the SMD-based predictions. For pK a calculations where a zwitterionic state is not involved or proton transfer in a zwitterionic state is not observed, PM3/COSMO or AM1/COSMO is the best pK a prediction method; otherwise PM3/SMD or AM1/SMD should be used. Thus, fast and relatively accurate pK a prediction for 100-1000s of druglike amines is feasible with the current setup and relatively modest computational resources.

Ultra-low fouling and high antibody loading zwitterionic hydrogel coatings for sensing and detection in complex media.

Science.gov (United States)

Chou, Ying-Nien; Sun, Fang; Hung, Hsiang-Chieh; Jain, Priyesh; Sinclair, Andrew; Zhang, Peng; Bai, Tao; Chang, Yung; Wen, Ten-Chin; Yu, Qiuming; Jiang, Shaoyi

2016-08-01

For surface-based diagnostic devices to achieve reliable biomarker detection in complex media such as blood, preventing nonspecific protein adsorption and incorporating high loading of biorecognition elements are paramount. In this work, a novel method to produce nonfouling zwitterionic hydrogel coatings was developed to achieve these goals. Poly(carboxybetaine acrylamide) (pCBAA) hydrogel thin films (CBHTFs) prepared with a carboxybetaine diacrylamide crosslinker (CBAAX) were coated on gold and silicon dioxide surfaces via a simple spin coating process. The thickness of CBHTFs could be precisely controlled between 15 and 150nm by varying the crosslinker concentration, and the films demonstrated excellent long-term stability. Protein adsorption from undiluted human blood serum onto the CBHTFs was measured with surface plasmon resonance (SPR). Hydrogel thin films greater than 20nm exhibited ultra-low fouling (crosslinked, purely zwitterionic, carboxybetaine thin film hydrogel (CBHTF) coating platform. The CBHTF on a hydrophilic surface demonstrated long-term stability. By varying the crosslinker content in the spin-coated hydrogel solution, the thickness of CBHTFs could be precisely controlled. Optimized CBHTFs exhibited ultra-low nonspecific protein adsorption below 5ng/cm(2) measured by a surface plasmon resonance (SPR) sensor, and their 3D architecture allowed antibody loading to reach 693ng/cm(2). This strategy provides a facile method to modify SPR biosensor chips with an advanced nonfouling material, and can be potentially expanded to a variety of implantable medical devices and diagnostic biosensors. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Derivation of the chemical-equilibrium rate coefficient using scattering theory

Science.gov (United States)

Mickens, R. E.

1977-01-01

Scattering theory is applied to derive the equilibrium rate coefficient for a general homogeneous chemical reaction involving ideal gases. The reaction rate is expressed in terms of the product of a number of normalized momentum distribution functions, the product of the number of molecules with a given internal energy state, and the spin-averaged T-matrix elements. An expression for momentum distribution at equilibrium for an arbitrary molecule is presented, and the number of molecules with a given internal-energy state is represented by an expression which includes the partition function.

Crosslinked copolyazoles with a zwitterionic structure for organic solvent resistant membranes

KAUST Repository

Chisca, Stefan

2015-01-01

The preparation of crosslinked membranes with a zwitterionic structure based on a facile reaction between a newly synthesized copolyazole with free OH groups and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) is reported. The new OH-functionalized copolyazole is soluble in common organic solvents, such as tetrahydrofuran (THF), dimethylsulfoxide (DMSO), N,N′-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) and can be easily processed by phase inversion. After crosslinking with GPTMS, the membranes acquire high solvent resistance. We show the membrane performance and the influence of the crosslinking reaction conditions on the thermal stability, surface polarity, pore morphology, and solvent resistance. By using UV-spectroscopy we monitored the solvent resistance of the membranes in four aggressive solvents (THF, DMSO, DMF and NMP) for 30 days. After this time, only minor changes (less than 2%) were detected for membranes subjected to a crosslinking reaction for 6 hours or longer. Our data suggest that the novel crosslinked membranes can be used for industrial applications in wide harsh environments in the presence of organic solvents.

Phenolic derivatives and other chemical compounds from Cochlospermum regium

International Nuclear Information System (INIS)

Solon, Soraya; Carollo, Carlos Alexandre; Brandao, Luiz Fabricio Gardini; Macedo, Cristiana dos Santos de; Klein, Andre; Dias-Junior, Carlos Alan; Siqueira, Joao Maximo de

2012-01-01

This study describes the chemical investigation of the ethyl acetate fraction obtained from the hydroethanolic extract of the xylopodium of Cochlospermum regium (Mart. and Schr.) Pilger, which has been associated with antimicrobial activity. Phytochemical investigation produced seven phenol derivatives: ellagic acid, gallic acid, dihydrokaempferol, dihydrokaempferol-3-ο-β-glucopyranoside, dihydrokaempferol-3-ο-β-(6''-galloyl)-glucopyranoside, pinoresinol, and excelsin. It also contained two triacylbenzenes, known as cochlospermines A and B. The hydroethanolic extract and its fractions exhibited antimicrobial activity (0.1 mg/mL) against Staphylococcus aureus and Pseudomonas aeruginosa. Gallic acid showed activity against S. aureus. Dihydrokaempferol-3-ο-β-(6 - galloyl)-glucopyranoside is reported here for the first time in the literature (author)

Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging

KAUST Repository

Kundhikanjana, Worasom

2009-11-11

Local electrical imaging using microwave impedance microscope is performed on graphene in different modalities, yielding a rich hierarchy of the local conductivity. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. For the conductive chemical graphene, the residual defects lead to a systematic reduction of the microwave signals. In contrast, the signals on pristine graphene agree well with a lumped-element circuit model. The local impedance information can also be used to verify the electrical contact between overlapped graphene pieces. © 2009 American Chemical Society.

Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro

International Nuclear Information System (INIS)

Liu, Xujie; Feng, Qingling; Bachhuka, Akash; Vasilev, Krasimir

2013-01-01

This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (-NH 2 ), carboxyl (-COOH) and methyl (-CH 3 ), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (-COOH and -NH 2 ) can absorb more proteins than these modified with more hydrophobic functional group (-CH 3 ). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the -NH 2 modified surfaces encourage osteogenic differentiation; the -COOH modified surfaces promote cell adhesion and spreading and the -CH 3 modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Liu, Xujie [State key laboratory of new ceramics and fine processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State key laboratory of new ceramics and fine processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Bachhuka, Akash [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); Vasilev, Krasimir [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); School of Advanced Manufacturing, University of South Australia, Mawson Lakes 5095 (Australia)

2013-04-01

This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (-NH{sub 2}), carboxyl (-COOH) and methyl (-CH{sub 3}), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (-COOH and -NH{sub 2}) can absorb more proteins than these modified with more hydrophobic functional group (-CH{sub 3}). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the -NH{sub 2} modified surfaces encourage osteogenic differentiation; the -COOH modified surfaces promote cell adhesion and spreading and the -CH{sub 3} modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

Comparing the Caputo, Caputo-Fabrizio and Atangana-Baleanu derivative with fractional order: Fractional cubic isothermal auto-catalytic chemical system

Science.gov (United States)

Saad, K. M.

2018-03-01

In this work we extend the standard model for a cubic isothermal auto-catalytic chemical system (CIACS) to a new model of a fractional cubic isothermal auto-catalytic chemical system (FCIACS) based on Caputo (C), Caputo-Fabrizio (CF) and Atangana-Baleanu in the Liouville-Caputo sense (ABC) fractional time derivatives, respectively. We present approximate solutions for these extended models using the q -homotopy analysis transform method ( q -HATM). We solve the FCIACS with the C derivative and compare our results with those obtained using the CF and ABC derivatives. The ranges of convergence of the solutions are found and the optimal values of h , the auxiliary parameter, are derived. Finally, these solutions are compared with numerical solutions of the various models obtained using finite differences and excellent agreement is found.

Library of Antifouling Surfaces Derived From Natural Amino Acids by Click Reaction.

Science.gov (United States)

Xu, Chen; Hu, Xin; Wang, Jie; Zhang, Ye-Min; Liu, Xiao-Jiu; Xie, Bin-Bin; Yao, Chen; Li, Yi; Li, Xin-Song

2015-08-12

Biofouling is of great concern in numerous applications ranging from ophthalmological implants to catheters, and from bioseparation to biosensors. In this report, a general and facile strategy to combat surface fouling is developed by grafting of amino acids onto polymer substrates to form zwitterionic structure through amino groups induced epoxy ring opening click reaction. First of all, a library of poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) hydrogels with zwitterionic surfaces were prepared, resulting in the formation of pairs of carboxyl anions and protonated secondary amino cations. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the successful immobilization of amino acids on the hydrogel surfaces. After that, the contact angle and equilibrium water content of the modified hydrogels showed that the hydrogels exhibited improved hydrophilicity compared with the parent hydrogel. Furthermore, the protein deposition was evaluated by bicinchoninic acid assay using bovine serum albumin (BSA) and lysozyme as models. The results indicated that the performance of the hydrogels was determined by the nature of incorporated amino acid: the hydrogels incorporated with neutral amino acids had nonspecific antiadsorption capability to both BSA and lysozyme; the hydrogels incorporated with charged amino acids showed antiadsorption behaviors against protein with same charge and enhanced adsorption to the protein with opposite charge; the optimal antiadsorption performance was observed on the hydrogels incorporated with polar amino acids with a hydroxyl residual. The improvement of antiprotein fouling of the neutral amino acids grafted hydrogels can be ascribed to the formation of zwitterionic surfaces. Finally, a couple of soft contact lenses grafted with amino acids were fabricated having improved antifouling property and hydrophilicity. The result demonstrated the success of

Facile modification of electrospun fibrous structures with antifouling zwitterionic hydrogels.

Science.gov (United States)

Xu, Tong; Yang, Jing; Zhang, Jiamin; Zhu, Yingnan; Li, Qingsi; Pan, Chao; Zhang, Lei

2017-12-28

Electrospinning technology can easily produce different shaped fibrous structures, making them highly valuable to various biomedical applications. However, surface contamination of biomolecules, cells, or blood has emerged as a significant challenge to the success of electrospun devices, especially artificial blood vessels, catheters and wound dressings etc. Many efforts have been made to resist the surface non-specific biomolecules or cells adsorption, but most of them require complex pre-treatment processes, hard-to-remove metal catalysts or rigorous reaction conditions. In addition, the stability of antifouling coatings, especially in complex conditions, is still a major concern. In this work, inspired by the interpenetrating polymer network and reinforced concrete structure, an efficient and facile strategy for modifying hydrophobic electrospun meshes and tubes with antifouling zwitterionic hydrogels has been introduced. The resulting products could efficiently resist the adhesion of proteins, cells, or even fresh whole blood. Meanwhile, they could maintain the shapes and mechanical strength of the original electrospun structures. Furthermore, the hydrogel structures could retain stable in a physiological condition for at least 3 months. This paper provided a general antifouling and hydrophilicity surface modification strategy for various fibrous structures, and could be of great value for many biomedical applications where antifouling properties are critical.

Improved surface property of PVDF membrane with amphiphilic zwitterionic copolymer as membrane additive

Energy Technology Data Exchange (ETDEWEB)

Li Jianhua, E-mail: jhli_2005@163.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Zhang Qiqing, E-mail: zhangqiq@126.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China) and Institute of Biomedical Engineering, Chinese Academy of Medical Science, Peking Union Medical College, Tianjin 300192 (China)

2012-06-15

An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.

Improved surface property of PVDF membrane with amphiphilic zwitterionic copolymer as membrane additive

International Nuclear Information System (INIS)

Li Jianhua; Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng; Zhang Qiqing

2012-01-01

An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.

High content screening of defined chemical libraries using normal and glioma-derived neural stem cell lines.

Science.gov (United States)

Danovi, Davide; Folarin, Amos A; Baranowski, Bart; Pollard, Steven M

2012-01-01

Small molecules with potent biological effects on the fate of normal and cancer-derived stem cells represent both useful research tools and new drug leads for regenerative medicine and oncology. Long-term expansion of mouse and human neural stem cells is possible using adherent monolayer culture. These cultures represent a useful cellular resource to carry out image-based high content screening of small chemical libraries. Improvements in automated microscopy, desktop computational power, and freely available image processing tools, now means that such chemical screens are realistic to undertake in individual academic laboratories. Here we outline a cost effective and versatile time lapse imaging strategy suitable for chemical screening. Protocols are described for the handling and screening of human fetal Neural Stem (NS) cell lines and their malignant counterparts, Glioblastoma-derived neural stem cells (GNS). We focus on identification of cytostatic and cytotoxic "hits" and discuss future possibilities and challenges for extending this approach to assay lineage commitment and differentiation. Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical and genetic tools to explore S1P biology.

Science.gov (United States)

Cahalan, Stuart M

2014-01-01

The zwitterionic lysophospholipid Sphingosine 1-Phosphate (S1P) is a pleiotropic mediator of physiology and pathology. The synthesis, transport, and degradation of S1P are tightly regulated to ensure that S1P is present in the proper concentrations in the proper location. The binding of S1P to five G protein-coupled S1P receptors regulates many physiological systems, particularly the immune and vascular systems. Our understanding of the functions of S1P has been aided by the tractability of the system to both chemical and genetic manipulation. Chemical modulators have been generated to affect most of the known components of S1P biology, including agonists of S1P receptors and inhibitors of enzymes regulating S1P production and degradation. Genetic knockouts and manipulations have been similarly engineered to disrupt the functions of individual S1P receptors or enzymes involved in S1P metabolism. This chapter will focus on the development and utilization of these chemical and genetic tools to explore the complex biology surrounding S1P and its receptors, with particular attention paid to the in vivo findings that these tools have allowed for.

Regenerable, innovative porous silicon-based polymer-derived ceramics for removal of methylene blue and rhodamine B from textile and environmental waters.

Science.gov (United States)

Bruzzoniti, Maria Concetta; Appendini, Marta; Onida, Barbara; Castiglioni, Michele; Del Bubba, Massimo; Vanzetti, Lia; Jana, Prasanta; Sorarù, Gian Domenico; Rivoira, Luca

2018-04-01

The presence of residual color in treated textile wastewater above the regulation limits is still a critical issue in many textile districts. Innovative, polymer-derived ceramics of the Si-C-O system were here synthesized in order to obtain porous nanocomposite materials where a free carbon phase is dispersed into a silicon carbide/silicon oxycarbide network. The sorbents were comprehensively characterized for the removal of two model water-soluble dyes (i.e., the cation methylene blue and the zwitterion rhodamine B). Adsorption is very rapid and controlled by intra-particle and/or film diffusion, depending on dye concentration. Among the nanocomposites studied, the SiOC aerogel (total capacity about 45 mg/g, is easily regenerated under mild treatment (250 °C, 2 h). Adsorption of dyes is not affected by the matrix composition: removals of 150 mg/L methylene blue from river water and simulated textile wastewater with high content of metal ions (2-50 mg/L) and chemical oxygen demand (800 mg/L) were higher than 92% and quantitative for a dye concentration of 1 mg/L.

Physical and chemical characterization of waste wood derived biochars.

Science.gov (United States)

Yargicoglu, Erin N; Sadasivam, Bala Yamini; Reddy, Krishna R; Spokas, Kurt

2015-02-01

Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties. Favorable properties of biochar include its high surface area and porosity, and ability to adsorb a variety of compounds, including nutrients, organic contaminants, and some gases. Physical and chemical properties of biochars are dictated by the feedstock and production processes (pyrolysis or gasification temperature, conversion technology and pre- and post-treatment processes, if any), which vary widely across commercially produced biochars. In this study, several commercially available biochars derived from waste wood are characterized for physical and chemical properties that can signify their relevant environmental applications. Parameters characterized include: physical properties (particle size distribution, specific gravity, density, porosity, surface area), hydraulic properties (hydraulic conductivity and water holding capacity), and chemical and electrochemical properties (organic matter and organic carbon contents, pH, oxidation-reduction potential and electrical conductivity, zeta potential, carbon, nitrogen and hydrogen (CHN) elemental composition, polycyclic aromatic hydrocarbons (PAHs), heavy metals, and leachable PAHs and heavy metals). A wide range of fixed carbon (0-47.8%), volatile matter (28-74.1%), and ash contents (1.5-65.7%) were observed among tested biochars. A high variability in surface area (0.1-155.1g/m(2)) and PAH and heavy metal contents of the solid phase among commercially available biochars was also observed (0.7-83 mg kg(-1)), underscoring the importance of pre-screening biochars prior to application. Production conditions appear to dictate PAH content--with the highest PAHs observed in biochar produced via fast pyrolysis and lowest among the gasification

Influence of wood-derived biochar on the physico-mechanical and chemical characteristics of agricultural soils

Science.gov (United States)

Ahmed, Ahmed S. F.; Raghavan, Vijaya

2018-01-01

Amendment of soil with biochar has been shown to enhance fertility and increase crop productivity, but the specific influence of biochar on soil workability remains unclear. Select physico-mechanical and chemical properties of clay loam and sandy loam soils were measured after amendment with wood-derived biochar of two particle size ranges (0.5-425 and 425-850 µm) at five dosages ranging from 0.5 to 10% dry weight. Whereas the clay loam soil workability decreased when the finer wood-derived biochar was applied at rates of 6 or 10%, soil fertility was not enhanced. The sandy loam soil, due to Proctor compaction, significantly decreased in bulk density with 6 and 10% wood-derived biochar amendments indicating higher soil resistance to compaction.

Phase and Texture Evolution in Chemically Derived PZT Thin Films on Pt Substrates

Science.gov (United States)

2014-09-01

function of heating rate. The FWHM of the Ill PZT texture components is sim 2978 Journal of the American Ceramic Society Mhin et al. Vol. 97, No. 9...Z39.18 ABSTRACT Phase and Texture Evolution in Chemically Derived PZT Thin Films on Pt Substrates Report Title The crystallization of lead zirconate...phase influencing texture evolution. The results suggest that PZT nucleates directly on Pt, which explains the observation of a more highly oriented

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

Directory of Open Access Journals (Sweden)

M. Fernanda N. N. Carvalho

2016-04-01

Full Text Available A camphor-derived sulfonimine with a conjugated carbonyl group, oxoimine 1 (O2SNC10H13O, reacts with amino acids (glycine, L-alanine, L-phenylalanine, L-leucine to form a compound O2SNC10H13NC10H14NSO2 (2 which was characterized by spectroscopic means (MS and NMR and supported by DFT calculations. The product, a single diastereoisomer, contains two oxoimine units connected by a –N= bridge, and thus has a structural analogy to the colored product Ruhemann´s purple obtained by the ninhydrin reaction with amino acids. A plausible reaction mechanism that involves zwitterions, a Strecker degradation of an intermediate imine and water-catalyzed tautomerizations was developed by means of DFT calculations on potential transition states.

In Situ Synthesis of Antimicrobial Silver Nanoparticles within Antifouling Zwitterionic Hydrogels by Catecholic Redox Chemistry for Wound Healing Application.

Science.gov (United States)

GhavamiNejad, Amin; Park, Chan Hee; Kim, Cheol Sang

2016-03-14

A multifunctional hydrogel that combines the dual functionality of both antifouling and antimicrobial capacities holds great potential for many bioapplications. Many approaches and different materials have been employed to synthesize such a material. However, a systematic study, including in vitro and in vivo evaluation, on such a material as wound dressings is highly scarce at present. Herein, we report on a new strategy that uses catecholic chemistry to synthesize antimicrobial silver nanoparticles impregnated into antifouling zwitterionic hydrogels. For this purpose, hydrophobic dopamine methacrylamide monomer (DMA) was mixed in an aqueous solution of sodium tetraborate decahydrate and DMA monomer became soluble after increasing pH to 9 due to the complexation between catechol groups and boron. Then, cross-linking polymerization of zwitterionic monomer was carried out with the solution of the protected dopamine monomer to produce a new hydrogel. When this new hydrogel comes in contact with a silver nitrate solution, silver nanoparticles (AgNPs) are formed in its structure as a result of the redox property of the catechol groups and in the absence of any other external reducing agent. The results obtained from TEM and XRD measurements indicate that AgNPs with diameters of around 20 nm had formed within the networks. FESEM images confirmed that the silver nanoparticles were homogeneously incorporated throughout the hydrogel network, and FTIR spectroscopy demonstrated that the catechol moiety in the polymeric backbone of the hydrogel is responsible for the reduction of silver ions into the AgNPs. Finally, the in vitro and in vivo experiments suggest that these mussel-inspired, antifouling, antibacterial hydrogels have great potential for use in wound healing applications.

Accumulation of plastic-derived chemicals in tissues of seabirds ingesting marine plastics.

Science.gov (United States)

Tanaka, Kosuke; Takada, Hideshige; Yamashita, Rei; Mizukawa, Kaoruko; Fukuwaka, Masa-aki; Watanuki, Yutaka

2013-04-15

We analyzed polybrominated diphenyl ethers (PBDEs) in abdominal adipose of oceanic seabirds (short-tailed shearwaters, Puffinus tenuirostris) collected in northern North Pacific Ocean. In 3 of 12 birds, we detected higher-brominated congeners (viz., BDE209 and BDE183), which are not present in the natural prey (pelagic fish) of the birds. The same compounds were present in plastic found in the stomachs of the 3 birds. These data suggested the transfer of plastic-derived chemicals from ingested plastics to the tissues of marine-based organisms. Copyright © 2012 Elsevier Ltd. All rights reserved.

The use of quantum chemically derived descriptors for QSAR modelling of reductive dehalogenation of aromatic compounds

NARCIS (Netherlands)

Rorije E; Richter J; Peijnenburg WJGM; ECO; IHE Delft

1994-01-01

In this study, quantum-chemically derived parameters are developed for a limited number of halogenated aromatic compounds to model the anaerobic reductive dehalogenation reaction rate constants of these compounds. It is shown that due to the heterogeneity of the set of compounds used, no single

Optimizing Performance Parameters of Chemically-Derived Graphene/p-Si Heterojunction Solar Cell.

Science.gov (United States)

Batra, Kamal; Nayak, Sasmita; Behura, Sanjay K; Jani, Omkar

2015-07-01

Chemically-derived graphene have been synthesized by modified Hummers method and reduced using sodium borohydride. To explore the potential for photovoltaic applications, graphene/p-silicon (Si) heterojunction devices were fabricated using a simple and cost effective technique called spin coating. The SEM analysis shows the formation of graphene oxide (GO) flakes which become smooth after reduction. The absence of oxygen containing functional groups, as observed in FT-IR spectra, reveals the reduction of GO, i.e., reduced graphene oxide (rGO). It was further confirmed by Raman analysis, which shows slight reduction in G-band intensity with respect to D-band. Hall effect measurement confirmed n-type nature of rGO. Therefore, an effort has been made to simu- late rGO/p-Si heterojunction device by using the one-dimensional solar cell capacitance software, considering the experimentally derived parameters. The detail analysis of the effects of Si thickness, graphene thickness and temperature on the performance of the device has been presented.

Diffusion of aqueous solutions of ionic, zwitterionic, and polar solutes

Science.gov (United States)

Teng, Xiaojing; Huang, Qi; Dharmawardhana, Chamila Chathuranga; Ichiye, Toshiko

2018-06-01

The properties of aqueous solutions of ionic, zwitterionic, and polar solutes are of interest to many fields. For instance, one of the many anomalous properties of aqueous solutions is the behavior of water diffusion in different monovalent salt solutions. In addition, solutes can affect the stabilities of macromolecules such as proteins in aqueous solution. Here, the diffusivities of aqueous solutions of sodium chloride, potassium chloride, tri-methylamine oxide (TMAO), urea, and TMAO-urea are examined in molecular dynamics simulations. The decrease in the diffusivity of water with the concentration of simple ions and urea can be described by a simple model in which the water molecules hydrogen bonded to the solutes are considered to diffuse at the same rate as the solutes, while the remainder of the water molecules are considered to be bulk and diffuse at almost the same rate as pure water. On the other hand, the decrease in the diffusivity of water with the concentration of TMAO is apparently affected by a decrease in the diffusion rate of the bulk water molecules in addition to the decrease due to the water molecules hydrogen bonded to TMAO. In other words, TMAO enhances the viscosity of water, while urea barely affects it. Overall, this separation of water molecules into those that are hydrogen bonded to solute and those that are bulk can provide a useful means of understanding the short- and long-range effects of solutes on water.

Controlled synthesis of gold nanostars by using a zwitterionic surfactant.

Science.gov (United States)

Casu, Alberto; Cabrini, Elisa; Donà, Alice; Falqui, Andrea; Diaz-Fernandez, Yuri; Milanese, Chiara; Taglietti, Angelo; Pallavicini, Piersandro

2012-07-23

By replacing cetyltrimethylammonium bromide (CTAB) with the zwitterionic lauryl sulfobetaine (LSB) surfactant in the classical seed-growth synthesis, monocrystalline gold nanostars (m-NS) and pentatwinned gold asymmetric nanostars (a-NS) were obtained instead of nanorods. The main product under all synthetic conditions was a-NS, which have branches with high aspect ratios (AR), thus leading to LSPR absorptions in the 750-1150 nm range. The percentage of m-NS versus a-NS, the aspect ratio of the a-NS branches, and consequently the position of their LSPR absorption can be finely tuned simply by regulating the concentration of reductant, the concentration of surfactant, or the concentration of the "catalytic" Ag(+) cation. The m-NS have instead shorter and larger branches, the AR of which is poorly influenced by synthetic conditions and displays an LSPR positioned around 700 nm. A growth mechanism that involves the direct contact of the sulfate moiety of LSB on the surface of the nano-object is proposed, thereby implying preferential coating of the {111} Au faces with weak interactions. Consistent with this, we also observed the straightforward complete displacement of the LSB surfactant from the surface of the nanostars. This was obtained by the simple addition of thiols in aqueous solution to yield extremely stable coated a-NS and m-NS that are resistant to highly acidic, basic, and in similar to in vivo conditions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Zwitterionic peptide anchored to conducting polymer PEDOT for the development of antifouling and ultrasensitive electrochemical DNA sensor.

Science.gov (United States)

Wang, Guixiang; Han, Rui; Su, Xiaoli; Li, Yinan; Xu, Guiyun; Luo, Xiliang

2017-06-15

Zwitterionic peptides were anchored to a conducting polymer of citrate doped poly(3,4-ethylenedioxythiophene) (PEDOT) via the nickel cation coordination, and the obtained peptide modified PEDOT, with excellent antifouling ability and good conductivity, was further used for the immobilization of a DNA probe to construct an electrochemical biosensor for the breast cancer marker BRCA1. The DNA biosensor was highly sensitive (with detection limit of 0.03fM) and selective, and it was able to detect BRCA1 in 5% (v/v) human plasma with satisfying accuracy and low fouling. The marriage of antifouling and biocompatible peptides with conducting polymers opened a new avenue to construct electrochemical biosensors capable of assaying targets in complex biological media with high sensitivity and without biofouling. Copyright © 2016 Elsevier B.V. All rights reserved.

Light-switchable polymer from cationic to zwitterionic form: synthesis, characterization, and interactions with DNA and bacterial cells.

Science.gov (United States)

Sobolčiak, Patrik; Spírek, Mário; Katrlík, Jaroslav; Gemeiner, Peter; Lacík, Igor; Kasák, Peter

2013-04-25

A novel cationic polymer poly(N,N-dimethyl-N-[3-(methacroylamino) propyl]-N-[2-[(2-nitrophenyl)methoxy]-2-oxo-ethyl]ammonium chloride) is synthesized by free-radical polymerization of N-[3-(dimethylamino)propyl] methacrylamide and subsequent quaternization with o-nitrobenzyl 2-chloroacetate. The photolabile o-nitrobenzyl carboxymethyl pendant moiety is transformed to the zwitterionic carboxybetaine form upon the irradiation at 365 nm. This feature is used to condense and, upon the light irradiation, to release double-strand DNA tested by gel electrophoresis and surface plasmon resonance experiments as well as to switch the antibacterial activity to non-toxic character demonstrated for Escherichia coli bacterial cells in solution and at the surface using the self-assembled monolayers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical nature of implant-derived titanium(IV) ions in synovial fluid

International Nuclear Information System (INIS)

Silwood, Christopher J.L.; Grootveld, Martin

2005-01-01

Previous investigations have indicated a deleterious leakage of Ti(III) and/or Ti(IV) species from Ti-Al-V alloy joint prostheses into adjacent tissue, synovium or synovial fluid (SF) in vivo. In view of the importance of the particular chemical nature of such complexes in determining their biological activity, we have employed high field proton ( 1 H) NMR spectroscopy to 'speciate' Ti(IV) in inflammatory SF. Treatment of osteoarthritic SF samples with increasing concentrations of Ti(IV) (0.10-1.03 mM [TiO(C 2 O 4 ) 2 ] 2- ) gave rise to a specific broadening of the citrate proton resonances, indicating that this bioavailable oxygen-donor ligand plays an important role in complexing implant-derived Ti(IV). 1 H NMR analysis of Ti(IV)-loaded SF samples subsequently treated with a large excess of ascorbate (0.05 M) showed that this added Ti(IV) chelator was only poorly effective in removing this metal ion from Ti(IV)-citrate/Ti(IV)-oxycitrate complexes. The results obtained here provide evidence for complexation of the low-molecular-mass (non-protein-bound) fraction of implant-derived Ti(IV) by citrate in vivo

Production of Plant Phthalate and its Hydrogenated Derivative from Bio-Based Platform Chemicals.

Science.gov (United States)

Lu, Rui; Lu, Fang; Si, Xiaoqin; Jiang, Huifang; Huang, Qianqian; Yu, Weiqiang; Kong, Xiangtao; Xu, Jie

2018-04-06

Direct transformation of bio-based platform chemicals into aromatic dicarboxylic acids and their derivatives, which are widely used for the manufacture of polymers, is of significant importance for the sustainable development of the plastics industry. However, limited successful chemical processes have been reported. This study concerns a sustainable route for the production of phthalate and its hydrogenated derivative from bio-based malic acid and erythritol. The key Diels-Alder reaction is applied to build a substituted cyclohexene structure. The dehydration reaction of malic acid affords fumaric acid with 96.6 % yield, which could be used as the dienophile, and 1,3-butadiene generated in situ through erythritol deoxydehydration serves as the diene. Starting from erythritol and dibutyl fumarate, a 74.3 % yield of dibutyl trans-4-cyclohexene-1,2-dicarboxylate is obtained. The palladium-catalyzed dehydrogenation of the cycloadduct gives a 77.8 % yield of dibutyl phthalate. Dibutyl trans-cyclohexane-1,2-dicarboxylate could be formed in nearly 100 % yield under mild conditions by hydrogenation of the cycloadduct. Furthermore, fumaric acid and fumarate, with trans configurations, were found to be better dienophiles for this Diels-Alder reaction than maleic acid and maleate, with cis configuration, based on the experimental and computational results. This new route will pave the way for the production of environmental friendly plastic materials from plants. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of derivatization reagents consisting of n-alkyl chloroformate/n-alcohol combinations in LC-ESI-MS/MS analysis of zwitterionic antiepileptic drugs.

Science.gov (United States)

Kostić, Nađa; Dotsikas, Yannis; Malenović, Anđelija; Medenica, Mirjana

2013-11-15

In the current study, three antiepileptic drugs with zwitterionic properties, namely vigabatrin, pregabalin and gabapentin, were chosen as model analytes to undergo derivatization by applying various n-alkyl chloroformate/n-alcohol combinations, followed by LC-ESI-MS/MS analysis. The employment of 16 combinations per drug using methyl, ethyl, propyl or butyl chloroformate coupled with methanol, ethanol, propanol or butanol, greatly affected a series of parameters of the derivatives, such as retention time on C8 column, signal expressed via areas, limit of detection values, as well as the yields of the main and side reactions. Practically, even slight modification of n-alkyl group of either chloroformate or alcohol resulted in significant changes in the chromatographic and mass spectrometric behavior of the novel derivative. It was clearly demonstrated that all the estimated parameters were highly correlated with the length of n-alkyl groups of the involved chloroformate and alcohol. The most significant influence was monitored in peak area values, indicating that the length of the n-alkyl chain plays an important role in electrospray ionization efficiency. For this parameter, increasing the n-alkyl chain from methyl to butyl led to increment up to 2089%, 508.7% and 1075% for area values of derivatized vigabatrin, pregabalin and gabapentin, respectively. These changes affected also the corresponding values of limits of detection, with the estimated improvements up to 1553%, 397.7% and 875.0% for the aforementioned derivatized drugs, respectively. Besides the obvious utilization of these conclusions in the development of bioanalytical methods for these analytes with the current protocol, this study offers valuable data which can be useful in more general approaches, giving insights into the effects of this derivatization reaction and its performances. Copyright © 2013 Elsevier B.V. All rights reserved.

Succinic acid production derived from carbohydrates: An energy and greenhouse gas assessment of a platform chemical toward a bio-based economy

NARCIS (Netherlands)

Cok, B.|info:eu-repo/dai/nl/371750679; Tsiropoulos, I.; Roes, A.L.|info:eu-repo/dai/nl/303022388; Patel, M.K.|info:eu-repo/dai/nl/18988097X

2014-01-01

Bio-based succinic acid has the potential to become a platform chemical, i.e. a key building block for deriving both commodity and high-value chemicals, which makes it an attractive compound in a bio-based economy. A few companies and industrial consortia have begun to develop its industrial

Plasmid-derived DNA Strand Displacement Gates for Implementing Chemical Reaction Networks.

Science.gov (United States)

Chen, Yuan-Jyue; Rao, Sundipta D; Seelig, Georg

2015-11-25

DNA nanotechnology requires large amounts of highly pure DNA as an engineering material. Plasmid DNA could meet this need since it is replicated with high fidelity, is readily amplified through bacterial culture and can be stored indefinitely in the form of bacterial glycerol stocks. However, the double-stranded nature of plasmid DNA has so far hindered its efficient use for construction of DNA nanostructures or devices that typically contain single-stranded or branched domains. In recent work, it was found that nicked double stranded DNA (ndsDNA) strand displacement gates could be sourced from plasmid DNA. The following is a protocol that details how these ndsDNA gates can be efficiently encoded in plasmids and can be derived from the plasmids through a small number of enzymatic processing steps. Also given is a protocol for testing ndsDNA gates using fluorescence kinetics measurements. NdsDNA gates can be used to implement arbitrary chemical reaction networks (CRNs) and thus provide a pathway towards the use of the CRN formalism as a prescriptive molecular programming language. To demonstrate this technology, a multi-step reaction cascade with catalytic kinetics is constructed. Further it is shown that plasmid-derived components perform better than identical components assembled from synthetic DNA.

Upgrading of lignocellulosic biorefinery to value-added chemicals: Sustainability and economics of bioethanol-derivatives

DEFF Research Database (Denmark)

Cheali, Peam; Posada, John A.; Gernaey, Krist

2015-01-01

with a sustainability assessment method is used as evaluation tool. First, an existing superstructure representing the lignocellulosic biorefinery design network is extended to include the options for catalytic conversion of bioethanol to value-added derivatives. Second, the optimization problem for process upgrade...... of operating profit for biorefineries producing bioethanol-derived chemicals (247 MM$/a and 241 MM$/a for diethyl ether and 1,3-butadiene, respectively). Second, the optimal designs for upgrading bioethanol (i.e. production of 1,3-butadiene and diethyl ether) performed also better with respect...... to sustainability compared with the petroleum-based processes. In both cases, the effects of the market price uncertainties were also analyzed by performing quantitative economic risk analysis and presented a significant risk of investment for a lignocellulosic biorefinery (12 MM$/a and 92 MM$/a for diethyl ether...

Synthesis and characterization of chemically activated carbon derived from arecanut shell

Directory of Open Access Journals (Sweden)

A. S. Jadhav

2016-03-01

Full Text Available Activated carbon (AC was prepared from areca-nut shell (AS by chemical activation using phosphoric acid (PA. Activated carbon was prepared in three batches using phosphoric acid of 50 gm, 100 gm, and 300 gm with varying impregnation ratios by weight of 1:1, 2:1 and 3:1, 4:1 each. Characterization of the prepared activated carbon was done by methylene blue number (MBN, iodine number (IN, acid adsorption test (AAT, and elemental composition. Activation was carried out at 400 C. It was found that activated carbon derived from areca-nut shell shown improved results for methylene blue number (MBN, iodine number (IN, and acid adsorption test(AAT. Thermal analysis was carried out to know the weight loss and SEM was performed to know the morphology of AC.

Both solubility and chemical stability of curcumin are enhanced by solid dispersion in cellulose derivative matrices.

Science.gov (United States)

Li, Bin; Konecke, Stephanie; Wegiel, Lindsay A; Taylor, Lynne S; Edgar, Kevin J

2013-10-15

Amorphous solid dispersions (ASD) of curcumin (Cur) in cellulose derivative matrices, hydroxypropylmethylcellulose acetate succinate (HPMCAS), carboxymethylcellulose acetate butyrate (CMCAB), and cellulose acetate adipate propionate (CAAdP) were prepared in order to investigate the structure-property relationship and identify polymer properties necessary to effectively increase Cur aqueous solution concentration. XRD results indicated that all investigated solid dispersions were amorphous, even at a 9:1 Cur:polymer ratio. Both stability against crystallization and Cur solution concentration from these ASDs were significantly higher than those from physical mixtures and crystalline Cur. Remarkably, curcumin was also stabilized against chemical degradation in solution. Chemical stabilization was polymer-dependent, with stabilization in CAAdP>CMCAB>HPMCAS>PVP, while matrices enhanced solution concentration as PVP>HPMCAS>CMCAB≈CAAdP. HPMCAS/Cur dispersions have useful combinations of pH-triggered release profile, chemical stabilization, and strong enhancement of Cur solution concentration. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Lipophilic IR-780 Dye-Encapsulated Zwitterionic Polymer-Lipid Micellar Nanoparticle for Enhanced Photothermal Therapy and NIR-Based Fluorescence Imaging in a Cervical Tumor Mouse Model

Directory of Open Access Journals (Sweden)

Santhosh Kalash Rajendrakumar

2018-04-01

Full Text Available To prolong blood circulation and avoid the triggering of immune responses, nanoparticles in the bloodstream require conjugation with polyethylene glycol (PEG. However, PEGylation hinders the interaction between the nanoparticles and the tumor cells and therefore limits the applications of PEGylated nanoparticles for therapeutic drug delivery. To overcome this limitation, zwitterionic materials can be used to enhance the systemic blood circulation and tumor-specific delivery of hydrophobic agents such as IR-780 iodide dye for photothermal therapy. Herein, we developed micellar nanoparticles using the amphiphilic homopolymer poly(12-(methacryloyloxydodecyl phosphorylcholine (PCB-lipid synthesized via reversible addition–fragmentation chain transfer (RAFT polymerization. The PCB-lipid can self-assemble into micelles and encapsulate IR-780 dye (PCB-lipid–IR-780. Our results demonstrated that PCB-lipid–IR-780 nanoparticle (NP exhibited low cytotoxicity and remarkable photothermal cytotoxicity to cervical cancer cells (TC-1 upon near-infrared (NIR laser irradiation. The biodistribution of PCB-lipid–IR-780 showed higher accumulation of PCB-lipid–IR-780 than that of free IR-780 in the TC-1 tumor. Furthermore, following NIR laser irradiation of the tumor region, the PCB-lipid–IR-780 accumulated in the tumor facilitated enhanced tumor ablation and subsequent tumor regression in the TC-1 xenograft model. Hence, these zwitterionic polymer-lipid hybrid micellar nanoparticles show great potential for cancer theranostics and might be beneficial for clinical applications.

Hydrodeoxygenation processes: advances on catalytic transformations of biomass-derived platform chemicals into hydrocarbon fuels.

Science.gov (United States)

De, Sudipta; Saha, Basudeb; Luque, Rafael

2015-02-01

Lignocellulosic biomass provides an attractive source of renewable carbon that can be sustainably converted into chemicals and fuels. Hydrodeoxygenation (HDO) processes have recently received considerable attention to upgrade biomass-derived feedstocks into liquid transportation fuels. The selection and design of HDO catalysts plays an important role to determine the success of the process. This review has been aimed to emphasize recent developments on HDO catalysts in effective transformations of biomass-derived platform molecules into hydrocarbon fuels with reduced oxygen content and improved H/C ratios. Liquid hydrocarbon fuels can be obtained by combining oxygen removal processes (e.g. dehydration, hydrogenation, hydrogenolysis, decarbonylation etc.) as well as by increasing the molecular weight via C-C coupling reactions (e.g. aldol condensation, ketonization, oligomerization, hydroxyalkylation etc.). Fundamentals and mechanistic aspects of the use of HDO catalysts in deoxygenation reactions will also be discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

40 CFR 721.1820 - Bisphenol derivative.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Bisphenol derivative. 721.1820 Section... Substances § 721.1820 Bisphenol derivative. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as bisphenol derivative (PMN No. P-92-509) is...

Mass production of chemicals from biomass-derived oil by directly atmospheric distillation coupled with co-pyrolysis

Science.gov (United States)

Zhang, Xue-Song; Yang, Guang-Xi; Jiang, Hong; Liu, Wu-Jun; Ding, Hong-Sheng

2013-01-01

Production of renewable commodity chemicals from bio-oil derived from fast pyrolysis of biomass has received considerable interests, but hindered by the presence of innumerable components in bio-oil. In present work, we proposed and experimentally demonstrated an innovative approach combining atmospheric distillation of bio-oil with co-pyrolysis for mass production of renewable chemicals from biomass, in which no waste was produced. It was estimated that 51.86 wt.% of distillate just containing dozens of separable organic components could be recovered using this approach. Ten protogenetic and three epigenetic compounds in distillate were qualitatively identified by gas chromatography/mass spectrometry and quantified by gas chromatography. Among them, the recovery efficiencies of acetic acid, propanoic acid, and furfural were all higher than 80 wt.%. Formation pathways of the distillate components in this process were explored. This work opens up a fascinating prospect for mass production of chemical feedstock from waste biomass. PMID:23350028

Tautomeric and Microscopic Protonation Equilibria of Anthranilic Acid and Its Derivatives.

Science.gov (United States)

Zapała, Lidia; Woźnicka, Elżbieta; Kalembkiewicz, Jan

2014-01-01

The acid-base chemistry of three zwitterionic compounds, namely anthranilic (2-aminobenzoic acid), N -methylanthranilic and N -phenylanthranilic acid has been characterized in terms of the macroconstants K a1 , K a2 , the isoelectric point p H I , the tautomerization constant K z and microconstants k 11 , k 12 , k 21 , k 22 . The potentiometric titration method was used to determine the macrodissociation constants. Due to the very poor water solubility of N -phenylanthranilic acid the dissociation constants p K a1 and p K a2 were determined in MDM-water mixtures [MDM is a co-solvent mixture, consisting of equal volumes of methanol (MeOH), dioxane and acetonitrile (MeCN)]. The Yasuda-Shedlovsky extrapolation procedure has been used to obtain the values of p K a1 and p K a2 in aqueous solutions. The p K a1 and p K a2 values obtained by this method are 2.86 ± 0.01 and 4.69 ± 0.03, respectively. The tautomerization constant K z describing the equilibrium between unionized form ⇌ zwitterionic form was evaluated by the K z method based on UV-VIS spectrometry. The method uses spectral differences between the zwitterionic form (found at isoelectric pH in aqueous solution) and the unionized form (formed in an organic solvent of low dielectric constant). The highest value of the K z constant has been observed in the case of N -methylantranilic acid (log 10 K z  = 1.31 ± 0.04). The values of log 10 K z for anthranilic and N -phenylanthranilic acids are similar and have values of 0.93 ± 0.03 and 0.90 ± 0.05, respectively. The results indicate that the tested compounds, in aqueous solution around the isoelectric point pH I , occur mainly in the zwitterionic form. Moreover, the influence of the type of substituent and pH of the aqueous phase on the equilibrium were analyzed with regard to the formation and the coexistence of different forms of the acids in the examined systems.

Bacterial resistance of self-assembled surfaces using PPOm-b-PSBMAn zwitterionic copolymer - concomitant effects of surface topography and surface chemistry on attachment of live bacteria.

Science.gov (United States)

Hsiao, Sheng-Wen; Venault, Antoine; Yang, Hui-Shan; Chang, Yung

2014-06-01

Three well-defined diblock copolymers made of poly(sulfobetaine methacrylate) (poly(SBMA)) and poly(propylene oxide) (PPO) groups were synthesized by atom transfer radical polymerization (ATRP) method. They were physically adsorbed onto three types of surfaces having different topography, including smooth flat surface, convex surface, and indented surface. Chemical state of surfaces was characterized by XPS while the various topographies were examined by SEM and AFM. Hydrophilicity of surfaces was dependent on both the surface chemistry and the surface topography, suggesting that orientation of copolymer brushes can be tuned in the design of surfaces aimed at resisting bacterial attachment. Escherichia coli, Staphylococcus epidermidis, Streptococcus mutans and Escherichia coli with green fluorescent protein (E. coli GFP) were used in bacterial tests to assess the resistance to bacterial attachment of poly(SBMA)-covered surfaces. Results highlighted a drastic improvement of resistance to bacterial adhesion with the increasing of poly(SBMA) to PPO ratio, as well as an important effect of surface topography. The chemical effect was directly related to the length of the hydrophilic moieties. When longer, more water could be entrapped, leading to improved anti-bacterial properties. The physical effect impacted on the orientation of the copolymer brushes, as well as on the surface contact area available. Convex surfaces as well as indented surfaces wafer presented the best resistance to bacterial adhesion. Indeed, bacterial attachment was more importantly reduced on these surfaces compared with smooth surfaces. It was explained by the non-orthogonal orientation of copolymer brushes, resulting in a more efficient surface coverage of zwitterionic molecules. This work suggests that not only the control of surface chemistry is essential in the preparation of surfaces resisting bacterial attachment, but also the control of surface topography and orientation of antifouling

Evaluation of Chemical Warfare Agent Percutaneous Vapor Toxicity: Derivation of Toxicity Guidelines for Assessing Chemical Protective Ensembles.

Energy Technology Data Exchange (ETDEWEB)

Watson, A.P.

2003-07-24

Percutaneous vapor toxicity guidelines are provided for assessment and selection of chemical protective ensembles (CPEs) to be used by civilian and military first responders operating in a chemical warfare agent vapor environment. The agents evaluated include the G-series and VX nerve agents, the vesicant sulfur mustard (agent HD) and, to a lesser extent, the vesicant Lewisite (agent L). The focus of this evaluation is percutaneous vapor permeation of CPEs and the resulting skin absorption, as inhalation and ocular exposures are assumed to be largely eliminated through use of SCBA and full-face protective masks. Selection of appropriately protective CPE designs and materials incorporates a variety of test parameters to ensure operability, practicality, and adequacy. One aspect of adequacy assessment should be based on systems tests, which focus on effective protection of the most vulnerable body regions (e.g., the groin area), as identified in this analysis. The toxicity range of agent-specific cumulative exposures (Cts) derived in this analysis can be used as decision guidelines for CPE acceptance, in conjunction with weighting consideration towards more susceptible body regions. This toxicity range is bounded by the percutaneous vapor estimated minimal effect (EME{sub pv}) Ct (as the lower end) and the 1% population threshold effect (ECt{sub 01}) estimate. Assumptions of exposure duration used in CPE certification should consider that each agent-specific percutaneous vapor cumulative exposure Ct for a given endpoint is a constant for exposure durations between 30 min and 2 hours.

Role of environmental chemicals, processed food derivatives, and nutrients in the induction of carcinogenesis.

Science.gov (United States)

Persano, Luca; Zagoura, Dimitra; Louisse, Jochem; Pistollato, Francesca

2015-10-15

In recent years it has been hypothesized that cancer stem cells (CSCs) are the actual driving force of tumor formation, highlighting the need to specifically target CSCs to successfully eradicate cancer growth and recurrence. Particularly, the deregulation of physiological signaling pathways controlling stem cell proliferation, self-renewal, differentiation, and metabolism is currently considered as one of the leading determinants of cancer formation. Given their peculiar, slow-dividing phenotype and their ability to respond to multiple microenvironmental stimuli, stem cells appear to be more susceptible to genetic and epigenetic carcinogens, possibly undergoing mutations resulting in tumor formation. In particular, some animal-derived bioactive nutrients and metabolites known to affect the hormonal milieu, and also chemicals derived from food processing and cooking, have been described as possible carcinogenic factors. Here, we review most recent literature in this field, highlighting how some environmental toxicants, some specific nutrients and their secondary products can induce carcinogenesis, possibly impacting stem cells and their niches, thus causing tumor growth.

Poromechanics Parameters of Fluid-Saturated Chemically Active Fibrous Media Derived from a Micromechanical Approach.

Science.gov (United States)

Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2013-01-01

The authors have derived macroscale poromechanics parameters for chemically active saturated fibrous media by combining microstructure-based homogenization with Hill's volume averaging. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's Lemmas. The advantage of this approach is that the resultant continuum model assumes a form suited to study porous materials, while retaining the effect of discrete fiber deformation. As a result, the model is able to predict the influence of microscale phenomena such as fiber buckling on the overall behavior, and in particular, on the poromechanics constants. The significance of the approach is demonstrated using the effect of drainage and fiber nonlinearity on monotonic compressive stress-strain behavior. The model predictions conform to the experimental observations for articular cartilage. The method can potentially be extended to other porous materials such as bone, clays, foams, and concrete.

Chemical synthesis of a Zwitterhormon, insulaxin, and of a relaxin-like bombyxin derivative.

Science.gov (United States)

Büllesbach, E E; Steinetz, B G; Schwabe, C

1996-07-30

The structural motif of insulin and relaxin is frequently seen in molecules of divergent functions and origins. The insect developmental factor bombyxin, the relaxin-like factor from Leydig cells, and the insulin-like factor 4 (INSL4) all are made of two disulfide-linked chains and have one disulfide bond within the A-chain. The polyclonal antibody R6, which was raised against porcine relaxin, reacts with a wide variety of naturally occurring relaxins from primates, marine and terrestrial mammals, and elasmobranchs but does not recognize insulin. The antibody binds mainly to the arginines that occur in the N, N+4 positions in the B-chains of all relaxins which also constitute the receptor-binding site. The receptor-binding haptens were incorporated by total synthesis into human despentapeptide insulin and bombyxin II, a developmental factor from the silk moth Bombyx mori. In the process the insect factor became a perfect antigen for the anti-relaxin antibody, whereas the human insulin was transformed into a bona fide relaxin. The conversion was affected by changing four critical residues so that the insulin activity was retained to the extent of 10% of the original level. This, to the best of our knowledge, is the first designer protein to incorporate two unrelated biological functions in one primary sequence, and we are therefore proposing that, analogous to zwitterion, the generic name "Zwitterhormon" (German spelling) be used for this type of construct.

PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM ...

Science.gov (United States)

This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations for 32 nonionic organic chemicals in sediment which are protective of the presence of freshwater and marine benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for the varying biological availability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms. EqP can be used to calculate ESBs for any toxicity endpoint for which there are water-only toxicity data; it is not limited to any single effect endpoint. For the purposes of this document, ESBs for 32 nonionic organic chemicals, including several low molecular weight aliphatic and aromatic compounds, pesticides, and phthalates, were derived using Final Chronic Values (FCV) from Water Quality Criteria (WQC) or Secondary Chronic Values (SCV) derived from existing toxicological data using the Great Lakes Water Quality Initiative (GLI) or narcosis theory approaches. These values are intended to be the concentration of each chemical in water that is protective of the presence of aquatic life. For nonionic organic chemicals demonstrating a narcotic mode of action, ESBs derived using the GLI approach specifically for fres

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.

Novel spirotetracyclic zwitterionic dual H(1)/5-HT(2A) receptor antagonists for the treatment of sleep disorders.

Science.gov (United States)

Gianotti, Massimo; Botta, Maurizio; Brough, Stephen; Carletti, Renzo; Castiglioni, Emiliano; Corti, Corrado; Dal-Cin, Michele; Delle Fratte, Sonia; Korajac, Denana; Lovric, Marija; Merlo, Giancarlo; Mesic, Milan; Pavone, Francesca; Piccoli, Laura; Rast, Slavko; Roscic, Maja; Sava, Anna; Smehil, Mario; Stasi, Luigi; Togninelli, Andrea; Wigglesworth, Mark J

2010-11-11

Histamine H(1) and serotonin 5-HT(2A) receptors mediate two different mechanisms involved in sleep regulation: H(1) antagonists are sleep inducers, while 5-HT(2A) antagonists are sleep maintainers. Starting from 9'a, a novel spirotetracyclic compound endowed with good H(1)/5-HT(2A) potency but poor selectivity, very high Cli, and a poor P450 profile, a specific optimization strategy was set up. In particular, we investigated the possibility of introducing appropriate amino acid moieties to optimize the developability profile of the series. Following this zwitterionic approach, we were able to identify several advanced leads (51, 65, and 73) with potent dual H(1)/5-HT(2A) activity and appropriate developability profiles. These compounds exhibited efficacy as hypnotic agents in a rat telemetric sleep model with minimal effective doses in the range 3-10 mg/kg po.

Chemical Exchange Saturation Transfer in Chemical Reactions: A Mechanistic Tool for NMR Detection and Characterization of Transient Intermediates.

Science.gov (United States)

Lokesh, N; Seegerer, Andreas; Hioe, Johnny; Gschwind, Ruth M

2018-02-07

The low sensitivity of NMR and transient key intermediates below detection limit are the central problems studying reaction mechanisms by NMR. Sensitivity can be enhanced by hyperpolarization techniques such as dynamic nuclear polarization or the incorporation/interaction of special hyperpolarized molecules. However, all of these techniques require special equipment, are restricted to selective reactions, or undesirably influence the reaction pathways. Here, we apply the chemical exchange saturation transfer (CEST) technique for the first time to NMR detect and characterize previously unobserved transient reaction intermediates in organocatalysis. The higher sensitivity of CEST and chemical equilibria present in the reaction pathway are exploited to access population and kinetics information on low populated intermediates. The potential of the method is demonstrated on the proline-catalyzed enamine formation for unprecedented in situ detection of a DPU stabilized zwitterionic iminium species, the elusive key intermediate between enamine and oxazolidinones. The quantitative analysis of CEST data at 250 K revealed the population ratio of [Z-iminium]/[exo-oxazolidinone] 0.02, relative free energy +8.1 kJ/mol (calculated +7.3 kJ/mol), and free energy barrier of +45.9 kJ/mol (ΔG ⧧ calc. (268 K) = +42.2 kJ/mol) for Z-iminium → exo-oxazolidinone. The findings underpin the iminium ion participation in enamine formation pathway corroborating our earlier theoretical prediction and help in better understanding. The reliability of CEST is validated using 1D EXSY-build-up techniques at low temperature (213 K). The CEST method thus serves as a new tool for mechanistic investigations in organocatalysis to access key information, such as chemical shifts, populations, and reaction kinetics of intermediates below the standard NMR detection limit.

Molecular dynamic and quantum chemical calculations for phthalazine derivatives as corrosion inhibitors of mild steel in 1 M HCl

Energy Technology Data Exchange (ETDEWEB)

Musa, Ahmed Y., E-mail: AMUSA6@UWO.CA [Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7 (Canada); Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor (Malaysia); Jalgham, Ramzi T.T.; Mohamad, Abu Bakar [Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor (Malaysia)

2012-03-15

Highlights: Black-Right-Pointing-Pointer The inhibition of three phthalazine derivatives was studied. Black-Right-Pointing-Pointer The inhibition efficiency increased in the following order: PTD < PT < PTO. Black-Right-Pointing-Pointer The adsorption energies were calculated using molecular dynamics simulations. Black-Right-Pointing-Pointer Quantum chemical parameters were calculated using the AM1, MNDO and PM3 methods. Black-Right-Pointing-Pointer The adsorption of phthalazine derivatives obeys the Langmuir adsorption isotherm. - Abstract: The abilities of phthalazine derivatives, including phthalazine (PT), phthalazone (PTO) and phthalhydrazide (PTD), to inhibit the corrosion of mild steel in 1 M HCl at 30 Degree-Sign C were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Theoretical calculations were performed to investigate the electronic structures of the PT derivatives. Our results showed that the inhibition efficiencies of these derivatives improved with increases in concentration. The data also showed that PTD < PT < PTO in terms of the inhibiting efficiency. Theoretical calculations also revealed that PTO is expected to be the best inhibitor among the studied phthalazine derivatives.

Integrated antibacterial and antifouling surfaces via cross-linking chitosan-g-eugenol/zwitterionic copolymer on electrospun membranes.

Science.gov (United States)

Li, Zhenguang; Hu, Wenhong; Zhao, Yunhui; Ren, Lixia; Yuan, Xiaoyan

2018-04-27

Integrated antibacterial and antifouling surfaces in favor of avoiding implant-related infections are necessarily required for biomaterials when they contact with the body fluid. In this work, an antibacterial and antifouling membrane was developed via cross-linking chitosan-g-eugenol and the zwitterionic copolymer poly(sulfobetaine methylacrylate-co-2-aminoethyl methacrylate) on the electrospun polycarbonate urethane substrate using genipin as a cross-linker. Antibacterial assays demonstrated that the prepared membranes had efficient antibacterial activity with 92.8 ± 2.5% and 95.2 ± 1.3% growth inhibition rates against Escherichia coli and Staphylococcus aureus, respectively. The investigations on antifouling activity and hemocompatibility of the membranes showed significant resistances to bacterial attachment, non-specific protein adsorption and platelet adhesion, and presented lower hemolytic activity and good anticoagulant activity as well. Moreover, cell culture assays indicated that the prepared membranes exerted no obvious cytotoxicity with more than 80% of relative L929 fibroblast viability. Therefore, the membranes with integrated antibacterial and antifouling properties could be potentially applied in promising indwelling devices. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantum mechanical effects in zwitterionic amino acids: The case of proline, hydroxyproline, and alanine in water

Science.gov (United States)

Ulman, Kanchan; Busch, Sebastian; Hassanali, Ali A.

2018-06-01

In this work, we use ab initio molecular dynamics simulations to elucidate the electronic properties of three hydrated zwitterionic amino acids, namely proline, hydroxyproline, and alanine, the former two forming an important constituent of collagen. In all three systems, we find a substantial amount of charge transfer between the amino acids and surrounding solvent, which, rather surprisingly, also involves the reorganization of electron density near the hydrophobic non-polar groups. Water around proline appears to be slightly more polarized, as reflected by the enhanced water dipole moment in its hydration shell. This observation is also complemented by an examination of the IR spectra of the three systems where there is a subtle red and blue shift in the O-H stretch and bend regions, respectively, for proline. We show that polarizability of these amino acids as revealed by a dipole moment analysis involves a significant enhancement from the solvent and that this also involves non-polar groups. Our results suggest that quantum mechanical effects are likely to be important in understanding the coupling between biomolecules and water in general and in hydrophobic interactions.

Chemical Microsensors For Detection Of Explosives And Chemical Warfare Agents

Science.gov (United States)

Yang, Xiaoguang; Swanson, Basil I.

2001-11-13

An article of manufacture is provided including a substrate having an oxide surface layer and a layer of a cyclodextrin derivative chemically bonded to said substrate, said layer of a cyclodextrin derivative adapted for the inclusion of selected compounds, e.g., nitro-containing organic compounds, therewith. Such an article can be a chemical microsensor capable of detecting a resultant mass change from inclusion of the nitro-containing organic compound.

Effect of surface topological structure and chemical modification of flame sprayed aluminum coatings on the colonization of Cylindrotheca closterium on their surfaces

Science.gov (United States)

Chen, Xiuyong; He, Xiaoyan; Suo, Xinkun; Huang, Jing; Gong, Yongfeng; Liu, Yi; Li, Hua

2016-12-01

Biofouling is one of the major problems for the coatings used for protecting marine infrastructures during their long-term services. Regulation in surface structure and local chemistry is usually the key for adjusting antifouling performances of the coatings. In this study, flame sprayed multi-layered aluminum coatings with micropatterned surfaces were constructed and the effects of their surface structure and chemistry on the settlement of typical marine diatoms were investigated. Micropatterned topographical morphology of the coatings was constructed by employing steel mesh as a shielding plate during the coating deposition. A silicone elastomer layer for sealing and interconnection was further brush-coated on the micropatterned coatings. Additional surface modification was made using zwitterionic molecules via DOPA linkage. The surface-modified coatings resist effectively colonization of Cylindrotheca closterium. This is explained by the quantitative examination of a simplified conditioning layer that deteriorated adsorption of bovine calf serum proteins on the zwitterionic molecule-treated samples is revealed. The colonization behaviors of the marine diatoms are markedly influenced by the micropatterned topographical morphology. Either the surface micropatterning or the surface modification by zwitterionic molecules enhances antimicrobial ability of the coatings. However, the combined micropatterned structure and zwitterionic modification do not show synergistic effect. The results give insight into anti-corrosion/fouling applications of the modified aluminum coatings in the marine environment.

Creation of antifouling microarrays by photopolymerization of zwitterionic compounds for protein assay and cell patterning.

Science.gov (United States)

Sun, Xiuhua; Wang, Huaixin; Wang, Yuanyuan; Gui, Taijiang; Wang, Ke; Gao, Changlu

2018-04-15

Nonspecific binding or adsorption of biomolecules presents as a major obstacle to higher sensitivity, specificity and reproducibility in microarray technology. We report herein a method to fabricate antifouling microarray via photopolymerization of biomimetic betaine compounds. In brief, carboxybetaine methacrylate was polymerized as arrays for protein sensing, while sulfobetaine methacrylate was polymerized as background. With the abundant carboxyl groups on array surfaces and zwitterionic polymers on the entire surfaces, this microarray allows biomolecular immobilization and recognition with low nonspecific interactions due to its antifouling property. Therefore, low concentration of target molecules can be captured and detected by this microarray. It was proved that a concentration of 10ngmL -1 bovine serum albumin in the sample matrix of bovine serum can be detected by the microarray derivatized with anti-bovine serum albumin. Moreover, with proper hydrophilic-hydrophobic designs, this approach can be applied to fabricate surface-tension droplet arrays, which allows surface-directed cell adhesion and growth. These light controllable approaches constitute a clear improvement in the design of antifouling interfaces, which may lead to greater flexibility in the development of interfacial architectures and wider application in blood contact microdevices. Copyright © 2017 Elsevier B.V. All rights reserved.

Zwitterionic phosphorylcholine grafted chitosan nanofiber: Preparation, characterization and in-vitro cell adhesion behavior

Energy Technology Data Exchange (ETDEWEB)

Oktay, Burcu; Kayaman-Apohan, Nilhan, E-mail: napohan@marmara.edu.tr; Süleymanoğlu, Mediha; Erdem-Kuruca, Serap

2017-04-01

In this study, zwitterionic phosphorylcholine grafted electrospun chitosan fiber was accomplished in three steps: (1) Azide groups on the chitosan were regioselectively replaced with hydroxyl side group and then the product was electrospun. (2) Chitosan based macroinitiator was prepared using an azide-alkyne click reaction from azide-functionalized electrospun chitosan fiber. (3) Poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) was grafted onto the electrospun chitosan fiber by atom transfer radical polymerization (ATRP) in order to enhance cellular viability and proliferation of 3T3, ECV and Saos. The structure of surface modified chitosan was characterized by Fourier transform infrared spectrometer (FT-IR) and {sup 1}H nuclear magnetic resonance ({sup 1}H NMR). The surface morphology of the nanofibers was investigated by scanning electron microscope (SEM). In-vitro cellular attachment and spreading experiments of 3T3, ECV304 and Saos were performed on electrospun chitosan fibers in the presence and the absence of MPC grafting. Poly(MPC) grafted electrospun fiber showed an excellent performance due to phosphorylcholine groups mimicking the natural phospholipid. - Highlights: • Chitosan was functionalized in a controlled way. • Poly(MPC) grafted electrospun chitosan fiber was prepared by click and ATRP. • Controlled molecular architecture was achieved. • Cellular attachment and spreading efficiency of the nanofiber were investigated. • These nanofibers have potential applications in tissue engineering with tissue.

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

In situ synthesis, electrochemical and quantum chemical analysis of an amino acid-derived ionic liquid inhibitor for corrosion protection of mild steel in 1M HCl solution

International Nuclear Information System (INIS)

Kowsari, E.; Arman, S.Y.; Shahini, M.H.; Zandi, H.; Ehsani, A.; Naderi, R.; PourghasemiHanza, A.; Mehdipour, M.

2016-01-01

Highlights: • Electrochemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Quantum chemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Finding correlation between electrochemical analysis and quantum chemical analysis. - Abstract: In this study, an amino acid-derived ionic liquid inhibitor, namely tetra-n-butyl ammonium methioninate, was synthesized and the role this inhibitor for corrosion protection of mild steel exposed to 1.0 M HCl was investigated using electrochemical, quantum and surface analysis. By taking advantage of potentiodynamic polarization, the inhibitory action of tetra-n-butyl ammonium methioninate was found to be mainly mixed-type with dominant anodic inhibition. The effectiveness of the inhibitor was also indicated using electrochemical impedance spectroscopy (EIS). Moreover, to provide further insight into the mechanism of inhibition, electrochemical noise (EN) and quantum chemical calculations of the inhibitor were performed.

Simple Protein Modification Using Zwitterionic Polymer to Mitigate the Bioactivity Loss of Conjugated Insulin.

Science.gov (United States)

Xie, Jinbing; Lu, Yang; Wang, Wei; Zhu, Hui; Wang, Zhigang; Cao, Zhiqiang

2017-06-01

Polymer-protein conjugation has been extensively explored toward a better protein drug with improved pharmacokinetics. However, a major problem with polymer-protein conjugation is that the polymers drastically reduce the bioactivity of the modified protein. There is no perfect solution to prevent the bioactivity loss, no matter the polymer is conjugated in a non-site specific way, or a more complex site-specific procedure. Here the authors report for the first time that when zwitterionic carboxybetaine polymer (PCB) is conjugated to insulin through simple conventional coupling chemistry. The resulting PCB-insulin does not show a significant reduction of in vitro bioactivity. The obtained PCB-insulin shows two significant advantages as a novel pharmaceutical agent. First, its therapeutic performance is remarkable. For PCB-insulin, there is a 24% increase of in vivo pharmacological activity of lowering blood glucose compared with native insulin. Such uncommonly seen increase has rarely been reported and is expected to be due to both the improved pharmacokinetics and retained bioactivity of PCB-insulin. Second, the production is simple from manufacturing standpoints. Conjugation procedure involves only one-step coupling reaction without complex site-specific linkage technique. The synthesized PCB-insulin conjugates do not require chromatographic separation to purify and obtain particular isoforms. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature dependent thermoelectric properties of chemically derived gallium zinc oxide thin films

KAUST Repository

Barasheed, Abeer Z.; Sarath Kumar, S. R.; Alshareef, Husam N.

2013-01-01

In this study, the temperature dependent thermoelectric properties of sol-gel prepared ZnO and 3% Ga-doped ZnO (GZO) thin films have been explored. The power factor of GZO films, as compared to ZnO, is improved by nearly 17% at high temperature. A stabilization anneal, prior to thermoelectric measurements, in a strongly reducing Ar/H2 (95/5) atmosphere at 500°C was found to effectively stabilize the chemically derived films, practically eliminating hysteresis during thermoelectric measurements. Subtle changes in the thermoelectric properties of stabilized films have been correlated to oxygen vacancies and excitonic levels that are known to exist in ZnO-based thin films. The role of Ga dopants and defects, formed upon annealing, in driving the observed complex temperature dependence of the thermoelectric properties is discussed. © The Royal Society of Chemistry 2013.

Vitamin D derivatives

International Nuclear Information System (INIS)

Deluca, H.F.; Schnoes, H.K.; Napoli, J.L.; Fivizzani, M.A.

1982-01-01

The chemical preparation of 26,27-isotopically labelled vitamin D 3 derivatives of high specific activity is described. These labelled vitamin D derivatives are useful in the determination of vitamin D metabolite levels in the blood and tissues of man and animals. (U.K.)

Novel, one-step synthesis of zwitterionic polymer nanoparticles via distillation-precipitation polymerization and its application for dye removal membrane.

Science.gov (United States)

Ibrahim, G P Syed; Isloor, Arun M; Inamuddin; Asiri, Abdullah M; Ismail, Norafiqah; Ismail, Ahmed Fauzi; Ashraf, Ghulam Md

2017-11-21

In this work, poly(MBAAm-co-SBMA) zwitterionic polymer nanoparticles were synthesized in one-step via distillation-precipitation polymerization (DPP) and were characterized. [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) as monomer and N, N'-methylene bis(acrylamide) (MBAAm) as cross-linker are used for the synthesis of nanoparticles. As  far as our knowledge, this is the first such report on the synthesis of poly(MBAAm-co-SBMA) nanoparticles via DPP. The newly synthesized nanoparticles were further employed for the surface modification of polysulfone (PSF) hollow fiber membranes for dye removal. The modified hollow fiber membrane exhibited the improved permeability (56 L/ m 2 h bar) and dye removal (>98% of Reactive Black 5 and >80.7% of Reactive orange 16) with the high permeation of salts. Therefore, the as-prepared membrane can have potential application in textile and industrial wastewater treatment.

The Influence of pH and Temperature on the Stability of N-[(Piperidinemethylene]daunorubicin Hydrochloride and a Comparison of the Stability of Daunorubicin and Its Four New Amidine Derivatives in Aqueous Solutions

Directory of Open Access Journals (Sweden)

Mikołaj Piekarski

2014-01-01

Full Text Available The influence of pH and temperature on the stability of N-[(piperidinemethylene]daunorubicin hydrochloride (PPD was investigated. Degradation was studied using an HPLC method. Specific acid-base catalysis of PPD involves hydrolysis of protonated molecules of PPD catalyzed by hydrogen ions and spontaneous hydrolysis under the influence of water zwitterions, unprotonated molecules, and monoanions of PPD. The thermodynamic parameters of these reactions, energy, enthalpy, and entropy, were calculated. Also, the stability of daunorubicin and its new amidine derivatives (piperidine, morpholine, pyrrolidine, and hexahydroazepin-1-yl in aqueous solutions was compared and discussed.

Prediction of pK_a values for druglike molecules using semiempirical quantum chemical methods

DEFF Research Database (Denmark)

Jensen, Jan Halborg; Swain, Christopher J; Olsen, Lars

2017-01-01

Rapid yet accurate pKa prediction for druglike molecules is a key challenge in computational chemistry. This study uses PM6-DH+/COSMO, PM6/COSMO, PM7/COSMO, PM3/COSMO, AM1/COSMO, PM3/SMD, AM1/SMD, and DFTB3/SMD to predict the pKa values of 53 amine groups in 48 druglike compounds. The approach uses...... uncertainties of ±0.2-0.3 pH units, which make them statistically equivalent. However, for all but PM3/SMD and AM1/SMD the RMSEs are dominated by a single outlier, cefadroxil, caused by proton transfer in the zwitterionic protonation state. If this outlier is removed, the RMSE values for PM3/COSMO and AM1/COSMO...... drop to 1.0 ± 0.2 and 1.1 ± 0.3, whereas PM3/SMD and AM1/SMD remain at 1.5 ± 0.3 and 1.6 ± 0.3/0.4 pH units, making the COSMO-based predictions statistically better than the SMD-based predictions. For pKa calculations where a zwitterionic state is not involved or proton transfer in a zwitterionic state...

Crystal structure of a 2:1 piroxicam–gentisic acid co-crystal featuring neutral and zwitterionic piroxicam molecules

Directory of Open Access Journals (Sweden)

Elizabeth M. Horstman

2016-12-01

Full Text Available A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hydroxy-1,1-dioxo-N-(pyridin-2-yl-2H-1λ6,2-benzothiazine-3-carboxamide–2-(4-oxido-1,1-dioxo-2H-1λ6,2-benzothiazine-3-amidopyridin-1-ium–2,5-dihydroxybenzoic acid, 2C15H13N3O4S·C7H6O4] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam molecule is in its neutral form and an intramolecular O—H...O hydrogen bond is observed. The other piroxicam molecule is zwitterionic (proton transfer from the OH group to the pyridine N atom and two intramolecular N—H...O hydrogen bonds occur. The gentisic acid molecule shows whole-molecule disorder over two sets of sites in a 0.809 (2:0.191 (2 ratio. In the crystal, extensive hydrogen bonding between the components forms layers propagating in the ab plane.

Macrocyclic Gd(3+) complexes with pendant crown ethers designed for binding zwitterionic neurotransmitters.

Science.gov (United States)

Oukhatar, Fatima; Meudal, Hervé; Landon, Céline; Logothetis, Nikos K; Platas-Iglesias, Carlos; Angelovski, Goran; Tóth, Éva

2015-07-27

A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM(-1)  s(-1) at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu(3+) complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non-amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vitro cardiotoxicity assessment of environmental chemicals using an organotypic human induced pluripotent stem cell-derived model

Energy Technology Data Exchange (ETDEWEB)

Sirenko, Oksana, E-mail: oksana.sirenko@moldev.com [Molecular Devices, LLC, Sunnyvale, CA (United States); Grimm, Fabian A. [Department of Veterinary Integrative Biosciences, Texas A& M University, College Station, TX (United States); Ryan, Kristen R. [Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States); Iwata, Yasuhiro; Chiu, Weihsueh A. [Department of Veterinary Integrative Biosciences, Texas A& M University, College Station, TX (United States); Parham, Frederick [Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States); Wignall, Jessica A. [ICF, Fairfax, VA (United States); Anson, Blake [Cellular Dynamics International, Madison, WI (United States); Cromwell, Evan F. [Protein Fluidics, Inc., Burlingame, CA (United States); Behl, Mamta [Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States); Rusyn, Ivan [Department of Veterinary Integrative Biosciences, Texas A& M University, College Station, TX (United States); Tice, Raymond R. [Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States)

2017-05-01

An important target area for addressing data gaps through in vitro screening is the detection of potential cardiotoxicants. Despite the fact that current conservative estimates relate at least 23% of all cardiovascular disease cases to environmental exposures, the identities of the causative agents remain largely uncharacterized. Here, we evaluate the feasibility of a combinatorial in vitro/in silico screening approach for functional and mechanistic cardiotoxicity profiling of environmental hazards using a library of 69 representative environmental chemicals and drugs. Human induced pluripotent stem cell-derived cardiomyocytes were exposed in concentration-response for 30 min or 24 h and effects on cardiomyocyte beating and cellular and mitochondrial toxicity were assessed by kinetic measurements of intracellular Ca{sup 2+} flux and high-content imaging using the nuclear dye Hoechst 33342, the cell viability marker Calcein AM, and the mitochondrial depolarization probe JC-10. More than half of the tested chemicals exhibited effects on cardiomyocyte beating after 30 min of exposure. In contrast, after 24 h, effects on cell beating without concomitant cytotoxicity were observed in about one third of the compounds. Concentration-response data for in vitro bioactivity phenotypes visualized using the Toxicological Prioritization Index (ToxPi) showed chemical class-specific clustering of environmental chemicals, including pesticides, flame retardants, and polycyclic aromatic hydrocarbons. For environmental chemicals with human exposure predictions, the activity-to-exposure ratios between modeled blood concentrations and in vitro bioactivity were between one and five orders of magnitude. These findings not only demonstrate that some ubiquitous environmental pollutants might have the potential at high exposure levels to alter cardiomyocyte function, but also indicate similarities in the mechanism of these effects both within and among chemicals and classes. - Highlights: �

In vitro cardiotoxicity assessment of environmental chemicals using an organotypic human induced pluripotent stem cell-derived model

International Nuclear Information System (INIS)

Sirenko, Oksana; Grimm, Fabian A.; Ryan, Kristen R.; Iwata, Yasuhiro; Chiu, Weihsueh A.; Parham, Frederick; Wignall, Jessica A.; Anson, Blake; Cromwell, Evan F.; Behl, Mamta; Rusyn, Ivan; Tice, Raymond R.

2017-01-01

An important target area for addressing data gaps through in vitro screening is the detection of potential cardiotoxicants. Despite the fact that current conservative estimates relate at least 23% of all cardiovascular disease cases to environmental exposures, the identities of the causative agents remain largely uncharacterized. Here, we evaluate the feasibility of a combinatorial in vitro/in silico screening approach for functional and mechanistic cardiotoxicity profiling of environmental hazards using a library of 69 representative environmental chemicals and drugs. Human induced pluripotent stem cell-derived cardiomyocytes were exposed in concentration-response for 30 min or 24 h and effects on cardiomyocyte beating and cellular and mitochondrial toxicity were assessed by kinetic measurements of intracellular Ca 2+ flux and high-content imaging using the nuclear dye Hoechst 33342, the cell viability marker Calcein AM, and the mitochondrial depolarization probe JC-10. More than half of the tested chemicals exhibited effects on cardiomyocyte beating after 30 min of exposure. In contrast, after 24 h, effects on cell beating without concomitant cytotoxicity were observed in about one third of the compounds. Concentration-response data for in vitro bioactivity phenotypes visualized using the Toxicological Prioritization Index (ToxPi) showed chemical class-specific clustering of environmental chemicals, including pesticides, flame retardants, and polycyclic aromatic hydrocarbons. For environmental chemicals with human exposure predictions, the activity-to-exposure ratios between modeled blood concentrations and in vitro bioactivity were between one and five orders of magnitude. These findings not only demonstrate that some ubiquitous environmental pollutants might have the potential at high exposure levels to alter cardiomyocyte function, but also indicate similarities in the mechanism of these effects both within and among chemicals and classes. - Highlights: �

Forced Spreading of Aqueous Solutions on Zwitterionic Sulfobetaine Surfaces for Rapid Evaporation and Solute Separation.

Science.gov (United States)

Wu, Cyuan-Jhang; Singh, Vickramjeet; Sheng, Yu-Jane; Tsao, Heng-Kwong

2017-08-01

Solute separation of aqueous mixtures is mainly dominated by water vaporization. The evaporation rate of an aqueous drop grows with increasing the liquid-gas interfacial area. The spontaneous spreading behavior of a water droplet on a total wetting surface provides huge liquid-gas interfacial area per unit volume; however, it is halted by the self-pinning phenomenon upon addition of nonvolatile solutes. In this work, it is shown that the solute-induced self-pinning can be overcome by gravity, leading to anisotropic spreading much faster than isotropic spreading. The evaporation rate of anisotropic spreading on a zwitterionic sulfobetaine surface is 25 times larger as that on a poly(methyl methacrylate) surface. Dramatic enhancement of evaporation is demonstrated by simultaneous formation of fog atop liquid film. During anisotropic spreading, the solutes are quickly precipitated out within 30 s, showing the rapid solute-water separation. After repeated spreading process for the dye-containing solution, the mean concentration of the collection is doubled, revealing the concentration efficiency as high as 100%. Gravity-enhanced spreading on total wetting surfaces at room temperature is easy to scale-up with less energy consumption, and thus it has great potentials for the applications of solute separation and concentration.

A unified algorithm for predicting partition coefficients for PBPK modeling of drugs and environmental chemicals

International Nuclear Information System (INIS)

Peyret, Thomas; Poulin, Patrick; Krishnan, Kannan

2010-01-01

The algorithms in the literature focusing to predict tissue:blood PC (P tb ) for environmental chemicals and tissue:plasma PC based on total (K p ) or unbound concentration (K pu ) for drugs differ in their consideration of binding to hemoglobin, plasma proteins and charged phospholipids. The objective of the present study was to develop a unified algorithm such that P tb , K p and K pu for both drugs and environmental chemicals could be predicted. The development of the unified algorithm was accomplished by integrating all mechanistic algorithms previously published to compute the PCs. Furthermore, the algorithm was structured in such a way as to facilitate predictions of the distribution of organic compounds at the macro (i.e. whole tissue) and micro (i.e. cells and fluids) levels. The resulting unified algorithm was applied to compute the rat P tb , K p or K pu of muscle (n = 174), liver (n = 139) and adipose tissue (n = 141) for acidic, neutral, zwitterionic and basic drugs as well as ketones, acetate esters, alcohols, aliphatic hydrocarbons, aromatic hydrocarbons and ethers. The unified algorithm reproduced adequately the values predicted previously by the published algorithms for a total of 142 drugs and chemicals. The sensitivity analysis demonstrated the relative importance of the various compound properties reflective of specific mechanistic determinants relevant to prediction of PC values of drugs and environmental chemicals. Overall, the present unified algorithm uniquely facilitates the computation of macro and micro level PCs for developing organ and cellular-level PBPK models for both chemicals and drugs.

Transformation of Zwitterionic Pyridine Derivatives to a Spiro-Fused Ring System: Azoniabenzo[de]fluorine. Synthesis and Mechanistic Rationalization.

Science.gov (United States)

Palkó, Roberta; Egyed, Orsolya; Rokob, Tibor András; Bombicz, Petra; Riedl, Zsuzsanna; Hajós, György

2015-01-02

Reaction of aryl- and benzylsulfanopyridinium amidates bearing a methyl group in position 6 with 2 equiv of diphenylketene afforded a spiro-fused ring system: azoniabenzo[de]fluorine. By use of an excess amount of ketene, a distinct reaction was observed via which a 1H-pyrrolo[3,2-b]pyridin-2(3H)-one derivative was furnished. The structure of the tetracyclic spiro-fused ring system was unambiguously confirmed by X-ray diffraction, and its formation was rationalized by DFT calculations.

Synthese von organischen und anorganischen Derivativen der Meldrumsäure

OpenAIRE

Al-Sheikh, Ahmad

2004-01-01

This dissertation concerns in the emphasis the synthesis and instrumental-analytic characterisation (NMR, X-ray, IR) of organic and inorganic derivatives of Meldrum's acid. The derivatives of Meldrum's acid classified as: 1.Zwitterionic derivatives of Meldrum's acid. 2. Salt derivatives of Meldrum's acid. 3. Neutral derivatives of Meldrum's acid Die Dissertation beschäftigt sich im Schwerpunkt mit der Synthese und instrumentell-analytischen Charakterisierung (NMR, X-ray, I...

Synthesis and physical-chemical properties of functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid

Directory of Open Access Journals (Sweden)

E. K. Mikhal’chenko

2017-08-01

Full Text Available Introduction. Synthetic research of new biologically active compounds occupies an important place in modern pharmaceutical science.Thus it is important to develop techniques for the biologically active substances functionalization. Esters and amides take special place among the variety of functional derivatives of organic acids,. These fragments are well-known pharmacophores and could be found in a wide range of drugs. Thus, the nootropic agent pyracetam is 2-oxo-1-pyrolidineacetamide, and is the selective antagonist of β-adrenoreceptores; atenolol is a derivative of benzeneacetamide. Substituted acetamide and ester fragments are also present in the structures of aprofen, spasmolitin, acetylidine and β-lactam cephalosporins and penicillins antibiotics.Aim of our research was the synthetic method development for functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid and the study of their physical-chemical properties. Materials and methods. Melting points were determined using capillary method on DMP (M. 1Н NMR-spectra were recorded by Varian Mercury VX-200 device (company «Varian» – USA solvent – (DMSO-d6, internal standard – ТМS. Elemental analysis of obtained compounds was produced on device Elementar Vario L cube. Chemical shifts were reported in ppm (parts per million values. Infrared (IR spectra were measured on a Bruker Alpha instrument using a potassium bromide (KBr disk, scanning from 400 to 4000 cm-1. Results and discussion. We selected 3-benzyl-8-propylxanthinyl-7-acetic acid as initial compound for our study. For synthesis of hexyl, heptyl, octyl, nonyl, decyl and benzyl esters of 3-benzyl-8-propylxanthinyl-7-acetic acid we used alternative method, that included alkylation of sodium salts of acids with alkyl halogens. Reaction was made at DMF medium by reflux of reagents. Next stage of our research was the synthesis of amides of 3-beznyl-8-propylxanthinyl-7-acetic acid by the reaction of ethyl or propyl esters

O-Succinyl-L-homoserine-based C4-chemical production: succinic acid, homoserine lactone, γ-butyrolactone, γ-butyrolactone derivatives, and 1,4-butanediol.

Science.gov (United States)

Hong, Kuk-Ki; Kim, Jeong Hyun; Yoon, Jong Hyun; Park, Hye-Min; Choi, Su Jin; Song, Gyu Hyeon; Lee, Jea Chun; Yang, Young-Lyeol; Shin, Hyun Kwan; Kim, Ju Nam; Cho, Kyung Ho; Lee, Jung Ho

2014-10-01

There has been a significant global interest to produce bulk chemicals from renewable resources using engineered microorganisms. Large research programs have been launched by academia and industry towards this goal. Particularly, C4 chemicals such as succinic acid (SA) and 1,4-butanediol have been leading the path towards the commercialization of biobased technology with the effort of replacing chemical production. Here we present O-Succinyl-L-homoserine (SH) as a new, potentially important platform biochemical and demonstrate its central role as an intermediate in the production of SA, homoserine lactone (HSL), γ-butyrolactone (GBL) and its derivatives, and 1,4-butanediol (BDO). This technology encompasses (1) the genetic manipulation of Escherichia coli to produce SH with high productivity, (2) hydrolysis into SA and homoserine (HS) or homoserine lactone hydrochloride, and (3) chemical conversion of either HS or homoserine lactone HCL (HSL·HCl) into drop-in chemicals in polymer industry. This production strategy with environmental benefits is discussed in the perspective of targeting of fermented product and a process direction compared to petroleum-based chemical conversion, which may reduce the overall manufacturing cost.

Differential reconstructed gene interaction networks for deriving toxicity threshold in chemical risk assessment.

Science.gov (United States)

Yang, Yi; Maxwell, Andrew; Zhang, Xiaowei; Wang, Nan; Perkins, Edward J; Zhang, Chaoyang; Gong, Ping

2013-01-01

. Findings from this proof-of-concept study suggest that our approach has a great potential in providing a novel and sensitive tool for threshold setting in chemical risk assessment. In future work, we plan to analyze more time-series datasets with a full spectrum of concentrations and sufficient replications per treatment. The pathway alteration-derived thresholds will also be compared with those derived from apical endpoints such as cell growth rate.

Crystal structure of a 2:1 piroxicam–gentisic acid co-crystal featuring neutral and zwitterionic piroxicam molecules

Energy Technology Data Exchange (ETDEWEB)

Horstman, Elizabeth M.; Bertke, Jeffery A.; Woods, Toby J.; Kenis, Paul J. A.

2016-11-04

A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hydroxy-1,1-dioxo-N-(pyridin-2-yl)-2H-1λ⁶,2-benzothiazine-3-carboxamide–2-(4-oxido-1,1-dioxo-2H-1λ⁶,2-benzothiazine-3-amido)pyridin-1-ium–2,5-dihydroxybenzoic acid, 2C₁₅H₁₃N₃O₄S·C₇H₆O₄] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam molecule is in its neutral form and an intramolecular O—H...O hydrogen bond is observed. The other piroxicam molecule is zwitterionic (proton transfer from the OH group to the pyridine N atom) and two intramolecular N—H...O hydrogen bonds occur. The gentisic acid molecule shows whole-molecule disorder over two sets of sites in a 0.809(2):0.191(2) ratio. In the crystal, extensive hydrogen bonding between the components forms layers propagating in theabplane.

Methacrylic Zwitterionic, Thermoresponsive, and Hydrophilic (Co)Polymers via Cu(0)-Polymerization: The Importance of Halide Salt Additives.

Science.gov (United States)

Simula, Alexandre; Anastasaki, Athina; Haddleton, David M

2016-02-01

The synthesis of hydrophilic, thermoresponsive, and zwitterionic polymethacrylates is reported by Cu(0)-mediated reversible deactivation radical polymerization in water and/or water/alcohol mixtures. The predisproportionation of [Cu(I) (PMDETA)Cl] in water prior to initiator and monomer addition is exploited to yield well-defined polymethacrylates with full monomer conversions in 30 min. The addition of supplementary halide salts (NaCl) enables the synthesis of various molecular weight poly[poly(ethylene glycol) methyl ether methacrylate] (PEGMA475) (DPn = 10-80, Mn ≈ 10,000-40 000 g mol(-1)) with full monomer conversion and narrow molecular weight distributions attained in all cases (Đ ≈ 1.20-1.30). A bifunctional PEG initiator (average Mn ≈ 1000 g mol(-1)) is utilized for the polymerization of a wide range of methacrylates including 2-dimethylaminoethyl methacrylate, 2-morpholinoethyl methacrylate, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, and 2-methacryloyloxyethyl phosphorylcholine. Despite the high water content, high end group fidelity is demonstrated by in situ chain extensions and block copolymerizations with PEGMA475 yielding well-defined functional telechelic pentablock copolymers within 2.5 h. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric

KAUST Repository

Nayak, Pradipta K.

2013-07-18

We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.

High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric

KAUST Repository

Nayak, Pradipta K.; Hedhili, Mohamed N.; Cha, Dong Kyu; Alshareef, Husam N.

2013-01-01

We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.

Preparation of functional composite materials based on chemically derived graphene using solution process

International Nuclear Information System (INIS)

Kim, M; Hyun, W J; Mun, S C; Park, O O

2015-01-01

Chemically derived graphenes were assembled into functional composite materials using solution process from stable solvent dispersion. We have developed foldable electronic circuits on paper substrates using vacuum filtration of graphene nanoplates dispersion and a selective transfer process without need for special equipment. The electronic circuits on paper substrates revealed only a small change in conductance under various folding angles and maintained an electronic path after repetitive folding and unfolding. We also prepared flexible. binder-free graphene paper-like materials by addition of graphene oxide as a film stabilizer. This graphene papers showed outstanding electrical conductivity up to 26,000 S/m and high charge capacity as an anode in lithium-ion battery without any post-treatments. For last case, multi-functional thin film structures of graphene nanoplates were fabricated by using layer-by-layer assembly technique, showing optical transparency, electrical conductivity and enhanced gas barrier property. (paper)

Biomass Derived Chemicals: Furfural Oxidative Esterification to Methyl-2-furoate over Gold Catalysts

Directory of Open Access Journals (Sweden)

Maela Manzoli

2016-07-01

Full Text Available The use of heterogeneous catalysis to upgrade biomass wastes coming from lignocellulose into higher value-added chemicals is one of the most explored subjects in the prospective vision of bio-refinery. In this frame, a lot of interest has been driven towards biomass-derived building block molecules, such as furfural. Gold supported catalysts have been successfully proven to be highly active and selective in the furfural oxidative esterification to methyl-2-furoate under mild conditions by employing oxygen as benign oxidant. Particular attention has been given to the studies in which the reaction occurs even without base as co-catalyst, which would lead to a more green and economically advantageous process. The Au catalysts are also stable and quite easily recovered and represent a feasible and promising route to efficiently convert furfural to methyl-2-furoate to be scaled up at industrial level.

Quantum Chemical and Experimental Studies on the Mechanism of Alkylation of β-Dicarbonyl Compounds. The Synthesis of Five and Six Membered Heterocyclic Spiro Derivatives

Directory of Open Access Journals (Sweden)

Ali Hüseyinli

2004-11-01

Full Text Available The alkylation of β-dicarbonyl compounds in a K2CO3/DMSO system wasfound to afford O- and C-alkylated derivatives, depending on the type of the β-dicarbonylcompound involved. The alkyl derivatives obtained were used in the synthesis of some newspiro barbituric acid derivatives. Quantum chemical calculations were carried out toelucidate the reaction mechanisms for some typical synthesis.

Influence of pyrolysis temperature on lead immobilization by chemically modified coconut fiber-derived biochars in aqueous environments.

Science.gov (United States)

Wu, Weidong; Li, Jianhong; Niazi, Nabeel Khan; Müller, Karin; Chu, Yingchao; Zhang, Lingling; Yuan, Guodong; Lu, Kouping; Song, Zhaoliang; Wang, Hailong

2016-11-01

Biochar has received widespread attention as an eco-friendly and efficient material for immobilization of toxic heavy metals in aqueous environments. In the present study, three types of coconut fiber-derived biochars were obtained by pyrolyzing at three temperatures, i.e., 300, 500, and 700 °C. In addition, nine types of biochars were prepared by chemical modification with ammonia, hydrogen peroxide, and nitric acid, respectively, which were used to investigate changes in physico-chemical properties by inter alia, Fourier transformation infrared spectrophotometry (FTIR), scanning electron microscope (SEM), and BET specific surface area analysis. Batch sorption experiments were carried out to determine the sorption capacity of the biochars for lead (Pb) in aqueous solutions. Results showed that the cation exchange capacity of biochar pyrolyzed at 300 °C and modified with nitric acid increased threefold compared to the control. Loosely corrugated carbon surface and uneven carbon surface of the biochar pyrolyzed at 300 °C were produced during ammonia and nitric acid modifications. Removal rate of Pb by the coconut biochar pyrolyzed at 300 °C and modified with ammonia was increased from 71.8 to 99.6 % compared to the untreated biochar in aqueous solutions containing 100 mg L -1 Pb. However, chemical modification did not enhance adsorption of Pb of the biochars pyrolyzed at higher temperatures (e.g., 500 or 700 °C), indicating that resistance of biochars to chemical treatment increased with pyrolysis temperature.

Tuning the probe location on zwitterionic micellar system with variation of pH and addition of surfactants with different alkyl chains: solvent and rotational relaxation studies.

Science.gov (United States)

Banerjee, Chiranjib; Mandal, Sarthak; Ghosh, Surajit; Rao, Vishal Govind; Sarkar, Nilmoni

2012-09-13

In this manuscript, we have modulated the location of an anionic probe, Coumarin-343 (C-343) in a zwitterionic (N-hexadecyl-N,N-dimethylammonio-1-propanesulfonate (SB-16)) micellar system by three different approaches. The effect of addition of the surfactant sodium dodecyl sulfate (SDS) and the room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium octylsulfate (EmimOs) and N,N-dimethylethanol hexanoate (DAH), to the micellar solution has been studied. The effect of pH variation has been studied as well using solvent and rotational measurements. Migration of the anionic probe, C-343, from the palisade layer of SB-16 micelle to the bulk water has been observed to varying extents with the addition of SDS and EmimOs. The effect is much more pronounced in the presence of SDS and can be ascribed to the presence of the long alkyl (dodecyl) chain on SDS which can easily orient itself and fuse inside the SB-16 micelle and facilitate the observed migration of the probe molecule. This phenomenon is confirmed by faster solvation and rotational relaxation of the investigated probe molecule. The analogous fusion process is difficult in case of EmimOs and DAH because of their comparatively smaller alkyl (octyl and hexanoate) chain. However, the direction of C-343 migration is reversed with the decrease of pH of the SB-16 micellar medium. An increase in the average solvation and rotational relaxation time of the probe in acidic medium has been observed. Since experimental conditions are maintained such that the probe molecules and the zwitterionic SB-16 micelles remain oppositely charged, the observed results can be attributed to the increased electrostatic interaction (attractive) between them. Temperature dependent study also supports this finding.

Expanding the chemical diversity of natural esters by engineering a polyketide-derived pathway into Escherichia coli.

Science.gov (United States)

Menendez-Bravo, Simón; Comba, Santiago; Sabatini, Martín; Arabolaza, Ana; Gramajo, Hugo

2014-07-01

Microbial fatty acid (FA)-derived molecules have emerged as promising alternatives to petroleum-based chemicals for reducing dependence on fossil hydrocarbons. However, native FA biosynthetic pathways often yield limited structural diversity, and therefore restricted physicochemical properties, of the end products by providing only a limited variety of usually linear hydrocarbons. Here we have engineered into Escherichia coli a mycocerosic polyketide synthase-based biosynthetic pathway from Mycobacterium tuberculosis and redefined its biological role towards the production of multi-methyl-branched-esters (MBEs) with novel chemical structures. Expression of FadD28, Mas and PapA5 enzymes enabled the biosynthesis of multi-methyl-branched-FA and their further esterification to an alcohol. The high substrate tolerance of these enzymes towards different FA and alcohol moieties resulted in the biosynthesis of a broad range of MBE. Further metabolic engineering of the MBE producer strain coupled this system to long-chain-alcohol biosynthetic pathways resulting in de novo production of branched wax esters following addition of only propionate. Copyright © 2014 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

1,3-Oxazin-6-one Derivatives and Bohemamine-Type Pyrrolizidine Alkaloids from a Marine-Derived Streptomyces spinoverrucosus.

Science.gov (United States)

Fu, Peng; La, Scott; MacMillan, John B

2016-03-25

Two new 1,3-oxazin-6-one derivatives (1 and 2) and six new bohemamine-type pyrrolizidine alkaloids (3-8) were isolated from the marine-derived Streptomyces spinoverrucosus strain SNB-048. Their structures including the absolute configurations were fully elucidated on the basis of spectroscopic analysis, ECD spectra, quantum chemical calculations, and chemical methods. Compounds 1 and 2 possess a γ-lactam moiety and a 1,3-oxazin-6-one system.

NMR spectroscopic studies of a TAT-derived model peptide in imidazolium-based ILs: influence on chemical shifts and the cis/trans equilibrium state.

Science.gov (United States)

Wiedemann, Christoph; Ohlenschläger, Oliver; Mrestani-Klaus, Carmen; Bordusa, Frank

2017-09-13

NMR spectroscopy was used to study systematically the impact of imidazolium-based ionic liquid (IL) solutions on a TAT-derived model peptide containing Xaa-Pro peptide bonds. The selected IL anions cover a wide range of the Hofmeister series of ions. Based on highly resolved one- and two-dimensional NMR spectra individual 1 H and 13 C peptide chemical shift differences were analysed and a classification of IL anions according to the Hofmeister series was derived. The observed chemical shift changes indicate significant interactions between the peptide and the ILs. In addition, we examined the impact of different ILs towards the cis/trans equilibrium state of the Xaa-Pro peptide bonds. In this context, the IL cations appear to be of exceptional importance for inducing an alteration of the native cis/trans equilibrium state of Xaa-Pro bonds in favour of the trans-isomers.

Molecular Design of Antifouling Polymer Brushes Using Sequence-Specific Peptoids.

Science.gov (United States)

Lau, King Hang Aaron; Sileika, Tadas S; Park, Sung Hyun; Sousa, Ana Maria Leal; Burch, Patrick; Szleifer, Igal; Messersmith, Phillip B

2015-01-07

Material systems that can be used to flexibly and precisely define the chemical nature and molecular arrangement of a surface would be invaluable for the control of complex biointerfacial interactions. For example, progress in antifouling polymer biointerfaces that prevent non-specific protein adsorption and cell attachment, which can significantly improve the performance of an array of biomedical and industrial applications, is hampered by a lack of chemical models to identify the molecular features conferring their properties. Poly(N-substituted glycine) "peptoids" are peptidomimetic polymers that can be conveniently synthesized with specific monomer sequences and chain lengths, and are presented as a versatile platform for investigating the molecular design of antifouling polymer brushes. Zwitterionic antifouling polymer brushes have captured significant recent attention, and a targeted library of zwitterionic peptoid brushes with a different charge densities, hydration, separations between charged groups, chain lengths, and grafted chain densities, is quantitatively evaluated for their antifouling properties through a range of protein adsorption and cell attachment assays. Specific zwitterionic brush designs were found to give rise to distinct but subtle differences in properties. The results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.

Selective Oxidation of Biomass-Derived Chemicals

DEFF Research Database (Denmark)

Modvig, Amalie Elise

. These processes should be able to compete with the established processes based on fossil resources. Glycolaldehyde is an often-observed by-product formed from degradation of larger sugars. Due to competing ecological and economical aspects of the well-established processes for extraction and conversion....... The objective of this dissertation was to develop new, alternative and sustainable methods for oxidative catalytic upgrading of biomass-derived compounds, with focus on oxidation of glycolaldehyde and simple alcohols as model substrates for larger sugars. Supported gold nanoparticle were studied...

Simulation of chemical reactions using fractional derivatives

International Nuclear Information System (INIS)

Zabadal, J.; Vilhena, M.; Livotto, P.

2001-01-01

In this work a new approach to solve time-dependant Schroedinger equation for molecular systems is proposed. The method employs functional derivatives to describe the time evolution of the wave functions in reactive systems, in order to establish the mechanisms and products of the reaction. A numerical simulation is reported

Optimal choice of pH for toxicity and bioaccumulation studies of ionizing organic chemicals

DEFF Research Database (Denmark)

Rendal, Cecilie; Kusk, Kresten Ole; Trapp, Stefan

2011-01-01

a dynamic flux model based on the Fick-Nernst-Planck diffusion equation known as the cell model. The cell model predicts that bases with delocalized charges may in some cases show declining bioaccumulation with increasing pH. Little information is available for amphoteric and zwitterionic compounds; however...

Chemical Graph Transformation with Stereo-Information

DEFF Research Database (Denmark)

Andersen, Jakob Lykke; Flamm, Christoph; Merkle, Daniel

2017-01-01

Double Pushout graph transformation naturally facilitates the modelling of chemical reactions: labelled undirected graphs model molecules and direct derivations model chemical reactions. However, the most straightforward modelling approach ignores the relative placement of atoms and their neighbo......Double Pushout graph transformation naturally facilitates the modelling of chemical reactions: labelled undirected graphs model molecules and direct derivations model chemical reactions. However, the most straightforward modelling approach ignores the relative placement of atoms...... and their neighbours in space. Stereoisomers of chemical compounds thus cannot be distinguished, even though their chemical activity may differ substantially. In this contribution we propose an extended chemical graph transformation system with attributes that encode information about local geometry. The modelling...... of graph transformation, but we here propose a framework that also allows for partially specified stereoinformation. While there are several stereochemical configurations to be considered, we focus here on the tetrahedral molecular shape, and suggest general principles for how to treat all other chemically...

Development of West-European PM2.5 and NO2 land use regression models incorporating satellite-derived and chemical transport modelling data

NARCIS (Netherlands)

de Hoogh, Kees; Gulliver, John; Donkelaar, Aaron van; Martin, Randall V; Marshall, Julian D; Bechle, Matthew J; Cesaroni, Giulia; Pradas, Marta Cirach; Dedele, Audrius; Eeftens, Marloes|info:eu-repo/dai/nl/315028300; Forsberg, Bertil; Galassi, Claudia; Heinrich, Joachim; Hoffmann, Barbara; Jacquemin, Bénédicte; Katsouyanni, Klea; Korek, Michal; Künzli, Nino; Lindley, Sarah J; Lepeule, Johanna; Meleux, Frederik; de Nazelle, Audrey; Nieuwenhuijsen, Mark; Nystad, Wenche; Raaschou-Nielsen, Ole; Peters, Annette; Peuch, Vincent-Henri; Rouil, Laurence; Udvardy, Orsolya; Slama, Rémy; Stempfelet, Morgane; Stephanou, Euripides G; Tsai, Ming Y; Yli-Tuomi, Tarja; Weinmayr, Gudrun; Brunekreef, Bert|info:eu-repo/dai/nl/067548180; Vienneau, Danielle; Hoek, Gerard|info:eu-repo/dai/nl/069553475

2016-01-01

Satellite-derived (SAT) and chemical transport model (CTM) estimates of PM2.5 and NO2 are increasingly used in combination with Land Use Regression (LUR) models. We aimed to compare the contribution of SAT and CTM data to the performance of LUR PM2.5 and NO2 models for Europe. Four sets of models,

Structure-based predictions of 13C-NMR chemical shifts for a series of 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles derivatives using GA-based MLR method

Science.gov (United States)

Ghavami, Raouf; Sadeghi, Faridoon; Rasouli, Zolikha; Djannati, Farhad

2012-12-01

Experimental values for the 13C NMR chemical shifts (ppm, TMS = 0) at 300 K ranging from 96.28 ppm (C4' of indole derivative 17) to 159.93 ppm (C4' of indole derivative 23) relative to deuteride chloroform (CDCl3, 77.0 ppm) or dimethylsulfoxide (DMSO, 39.50 ppm) as internal reference in CDCl3 or DMSO-d6 solutions have been collected from literature for thirty 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indole derivatives containing different substituted groups. An effective quantitative structure-property relationship (QSPR) models were built using hybrid method combining genetic algorithm (GA) based on stepwise selection multiple linear regression (SWS-MLR) as feature-selection tools and correlation models between each carbon atom of indole derivative and calculated descriptors. Each compound was depicted by molecular structural descriptors that encode constitutional, topological, geometrical, electrostatic, and quantum chemical features. The accuracy of all developed models were confirmed using different types of internal and external procedures and various statistical tests. Furthermore, the domain of applicability for each model which indicates the area of reliable predictions was defined.

Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering.

Science.gov (United States)

Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Rigogliuso, Salvatrice; Ghersi, Giulio; Giammona, Gaetano

2013-07-01

In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Antifouling aptasensor for the detection of adenosine triphosphate in biological media based on mixed self-assembled aptamer and zwitterionic peptide.

Science.gov (United States)

Wang, Guixiang; Su, Xiaoli; Xu, Qingjun; Xu, Guiyun; Lin, Jiehua; Luo, Xiliang

2018-03-15

Direct detection of targets in complex biological media with conventional biosensors is an enormous challenge due to the nonspecific adsorption and severe biofouling. In this work, a facile strategy for sensitive and low fouling detection of adenosine triphosphate (ATP) is developed through the construction of a mixed self-assembled biosensing interface, which was composed of zwitterionic peptide (antifouling material) and ATP aptamer (bio-recognition element). The peptide and aptamer (both containing thiol groups) were simultaneously self-assembled onto gold electrode surface electrodeposited with gold nanoparticles. The developed aptasensor possessed high selectivity and sensitivity for ATP, and it showed a wide linear response range towards ATP from 0.1pM to 5nM. Owing to the presence of peptide with excellent antifouling property in the biosensing interface, the aptasensor can detect ATP in complex biological media with remarkably reduced biofouling or nonspecific adsorption effect. Moreover, it can directly detect ATP in 1% human whole blood without suffering from any significant interference, indicating its great potential for practical assaying of ATP in biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Supramolecular Derivation of Graphene Nanomaterials for Chemical Sensors

DEFF Research Database (Denmark)

Olsen, Gunnar

With properties such as high surface area, high conductivity, and low production cost with easy up-scaling, graphene-like materials provide a promising support for many applications, one of which is for chemical sensors. By functionalization with molecular receptors such as supramolecular moieties...... of 10−5 M. In the second approach Azido-RGO was prepared as a general platform for post reduction modification. GO was here functionalized with a short linker terminated in an alcohol. The intermediate material was then reduced effectively with NaBH4, followed by chemical transformation of the alcohol...... atoms or slightly more than one azide per nm2 of RGO-sheet. This Azido-RGO was used in successful functionalization with the large supramolecular receptor molecules TTF-calix[4]pyrrole which function as a sensor for Cl− and potentially for TNB. The coverage achieved was one molecule per 50 – 60 carbon...

Maternally derived chemical defences are an effective deterrent against some predators of poison frog tadpoles (Oophaga pumilio).

Science.gov (United States)

Stynoski, Jennifer L; Shelton, Georgia; Stynoski, Peter

2014-05-01

Parents defend their young in many ways, including provisioning chemical defences. Recent work in a poison frog system offers the first example of an animal that provisions its young with alkaloids after hatching or birth rather than before. But it is not yet known whether maternally derived alkaloids are an effective defence against offspring predators. We identified the predators of Oophaga pumilio tadpoles and conducted laboratory and field choice tests to determine whether predators are deterred by alkaloids in tadpoles. We found that snakes, spiders and beetle larvae are common predators of O. pumilio tadpoles. Snakes were not deterred by alkaloids in tadpoles. However, spiders were less likely to consume mother-fed O. pumilio tadpoles than either alkaloid-free tadpoles of the red-eyed treefrog, Agalychnis callidryas, or alkaloid-free O. pumilio tadpoles that had been hand-fed with A. callidryas eggs. Thus, maternally derived alkaloids reduce the risk of predation for tadpoles, but only against some predators. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

An integrated multi-label classifier with chemical-chemical interactions for prediction of chemical toxicity effects.

Science.gov (United States)

Liu, Tao; Chen, Lei; Pan, Xiaoyong

2018-05-31

Chemical toxicity effect is one of the major reasons for declining candidate drugs. Detecting the toxicity effects of all chemicals can accelerate the procedures of drug discovery. However, it is time-consuming and expensive to identify the toxicity effects of a given chemical through traditional experiments. Designing quick, reliable and non-animal-involved computational methods is an alternative way. In this study, a novel integrated multi-label classifier was proposed. First, based on five types of chemical-chemical interactions retrieved from STITCH, each of which is derived from one aspect of chemicals, five individual classifiers were built. Then, several integrated classifiers were built by integrating some or all individual classifiers. By testing the integrated classifiers on a dataset with chemicals and their toxicity effects in Accelrys Toxicity database and non-toxic chemicals with their performance evaluated by jackknife test, an optimal integrated classifier was selected as the proposed classifier, which provided quite high prediction accuracies and wide applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Cinnamic Acid Derivatives as Antidiabetics Agents

Directory of Open Access Journals (Sweden)

Teni Ernawati

2017-04-01

Full Text Available Diabetes mellitus is a metabolic disorder of carbohydrate metabolism. Treatment of type II diabetes is usually done by prescribing diet and exercise for the patient however it can also be treated with antidiabetic drugs. The purpose of this paper is to illustrate some cinnamic acid derivative compounds which are either isolated from natural materials or the results of the chemical synthesis. In addition, their biological activities as an agent of α-glucosidase inhibitors have also been evaluated. Chemically, cinnamic acid has three main functional groups:  first is the substitution on the phenyl group, second is the additive reaction into the α-β unsaturated, and third is the chemical reaction with carboxylic acid functional groups. Chemical aspects of cinnamic acid derivative compounds have received much attention in the research and development of drugs, especially modifications within three functional groups are very influential. In the last 10 years, a lot of research and development of cinnamic acid derivatives as inhibitors of the α-glucosidase enzyme has been done. One example of the research done in this field is the modification of para position in the structure of cinnamic acid and addition of alkyl groups in the carboxylic group which would increase the activity of the α-glucosidase enzyme therefore the level of inhibition is 100 times higher than that of cinnamic acid compound itself. The novelty of this review article is to focus on the antidiabetic activity of cinnamic acid derivatives.

Physico-Chemical and Structural Interpretation of Discrete Derivative Indices on N-Tuples Atoms

Science.gov (United States)

Martínez-Santiago, Oscar; Marrero-Ponce, Yovani; Barigye, Stephen J.; Le Thi Thu, Huong; Torres, F. Javier; Zambrano, Cesar H.; Muñiz Olite, Jorge L.; Cruz-Monteagudo, Maykel; Vivas-Reyes, Ricardo; Vázquez Infante, Liliana; Artiles Martínez, Luis M.

2016-01-01

This report examines the interpretation of the Graph Derivative Indices (GDIs) from three different perspectives (i.e., in structural, steric and electronic terms). It is found that the individual vertex frequencies may be expressed in terms of the geometrical and electronic reactivity of the atoms and bonds, respectively. On the other hand, it is demonstrated that the GDIs are sensitive to progressive structural modifications in terms of: size, ramifications, electronic richness, conjugation effects and molecular symmetry. Moreover, it is observed that the GDIs quantify the interaction capacity among molecules and codify information on the activation entropy. A structure property relationship study reveals that there exists a direct correspondence between the individual frequencies of atoms and Hückel’s Free Valence, as well as between the atomic GDIs and the chemical shift in NMR, which collectively validates the theory that these indices codify steric and electronic information of the atoms in a molecule. Taking in consideration the regularity and coherence found in experiments performed with the GDIs, it is possible to say that GDIs possess plausible interpretation in structural and physicochemical terms. PMID:27240357

Chromatographic separation of metal cations on silica gel chemically modified with a polymeric derivative of diaza-18-crown-6

International Nuclear Information System (INIS)

Basyuk, V.A.

1991-01-01

Sorbent on the basis of γ-aminopropyl silica gel, containing chemically grafted polymer derivatives of diaza-18-crown-6, has been synthesized. Retaining of certain metal cations when acid mobile phases are used is studied. Acetate buffer solution, 0.005% aqueous solution of acetic acid and 10 mM aqueous solution of oxalic acid were used as mobile phases. Rare earth cations (including Sr 2+ ones) are weakly retained when any mobile phase is used. Retention of VO 2+ cations is the strongest one

DARK Classics in Chemical Neuroscience: Cathinone-Derived Psychostimulants.

Science.gov (United States)

Simmons, Steven J; Leyrer-Jackson, Jonna M; Oliver, Chicora F; Hicks, Callum; Muschamp, John W; Rawls, Scott M; Olive, M Foster

2018-05-11

Cathinone is a plant alkaloid found in khat leaves of perennial shrubs grown in East Africa. Similar to cocaine, cathinone elicits psychostimulant effects which are in part attributed to its amphetamine-like structure. Around 2010, home laboratories began altering the parent structure of cathinone to synthesize derivatives with mechanisms of action, potencies, and pharmacokinetics permitting high abuse potential and toxicity. These "synthetic cathinones" include 4-methylmethcathinone (mephedrone), 3,4-methylenedioxypyrovalerone (MDPV), and the empathogenic agent 3,4-methylenedioxymethcathinone (methylone) which collectively gained international popularity following aggressive online marketing as well as availability in various retail outlets. Case reports made clear the health risks associated with these agents and, in 2012, the Drug Enforcement Agency of the United States placed a series of synthetic cathinones on Schedule I under emergency order. Mechanistically, cathinone and synthetic derivatives work by augmenting monoamine transmission through release facilitation and/or presynaptic transport inhibition. Animal studies confirm the rewarding and reinforcing properties of synthetic cathinones by utilizing self-administration, place conditioning, and intracranial self-stimulation assays and additionally show persistent neuropathological features which demonstrate a clear need to better understand this class of drugs. This Review will thus detail (i) historical context of cathinone use and the rise of "dark" synthetic derivatives, (ii) structural features and mechanisms of synthetic cathinones, (iii) behavioral effects observed clinically and in animals under controlled laboratory conditions, and (iv) neurotransmitters and circuits that may be targeted to manage synthetic cathinone abuse in humans.

Effect of electrostatic interaction between fluoxetine and lipid membranes on the partitioning of fluoxetine investigated using second derivative spectrophotometry and FTIR.

Science.gov (United States)

Do, Tien T T; Dao, Uyen P N; Bui, Huong T; Nguyen, Trang T

2017-10-01

The interaction between a drug molecule and lipid bilayers is highly important regarding the pharmaceutical activity of the drug. In this study, the interaction of fluoxetine, a well-known selective serotonin reuptake inhibitor antidepressant and lipid bilayers composed of 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was studied from the aspect of electrostatics using second derivative spectrophotometry and Fourier transform infrared spectroscopy (FTIR) in order to provide insights into the drug behavior. Changing pH from 7.4 to 9.5 to increases the neutral state of fluoxetine, the partitioning of fluoxetine into the zwitterionic DPPC large unilamellar vesicles (LUVs) was increased whereas it was reduced into the negatively charged DPPG LUVs. Fluoxetine was found to exhibit a disordering effect on the acyl chains of DPPC and DPPG bilayers upon its partitioning. In addition, increasing concentration of NaCl lessened the binding of fluoxetine into DPPG bilayers due to the reduction in electrostatic attraction between positively charged fluoxetine and negatively charged DPPG LUVs. In addition, the FTIR study revealed that increasing the NaCl concentration could trigger the shift to higher frequency of the CH 2 stretching as well as the notable blue shift in the PO 2 - regions of DPPG, indicating that fluoxetine had deeper penetration into DPPG LUVs. The differences in the NaCl concentration showed a negligible effect on the incorporation of fluoxetine into the zwitterionic DPPC LUVs. In summary, the electrostatic interaction plays an important role on the partitioning of a cationic amphiphilic SSIR drug into the lipid bilayers and the drug partitioning induces the lipids' conformational change. These imply a possible influence on the drug pharmacology. Copyright © 2017 Elsevier B.V. All rights reserved.

Virtual quantification of metabolites by capillary electrophoresis-electrospray ionization-mass spectrometry: predicting ionization efficiency without chemical standards.

Science.gov (United States)

Chalcraft, Kenneth R; Lee, Richard; Mills, Casandra; Britz-McKibbin, Philip

2009-04-01

A major obstacle in metabolomics remains the identification and quantification of a large fraction of unknown metabolites in complex biological samples when purified standards are unavailable. Herein we introduce a multivariate strategy for de novo quantification of cationic/zwitterionic metabolites using capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) based on fundamental molecular, thermodynamic, and electrokinetic properties of an ion. Multivariate calibration was used to derive a quantitative relationship between the measured relative response factor (RRF) of polar metabolites with respect to four physicochemical properties associated with ion evaporation in ESI-MS, namely, molecular volume (MV), octanol-water distribution coefficient (log D), absolute mobility (mu(o)), and effective charge (z(eff)). Our studies revealed that a limited set of intrinsic solute properties can be used to predict the RRF of various classes of metabolites (e.g., amino acids, amines, peptides, acylcarnitines, nucleosides, etc.) with reasonable accuracy and robustness provided that an appropriate training set is validated and ion responses are normalized to an internal standard(s). The applicability of the multivariate model to quantify micromolar levels of metabolites spiked in red blood cell (RBC) lysates was also examined by CE-ESI-MS without significant matrix effects caused by involatile salts and/or major co-ion interferences. This work demonstrates the feasibility for virtual quantification of low-abundance metabolites and their isomers in real-world samples using physicochemical properties estimated by computer modeling, while providing deeper insight into the wide disparity of solute responses in ESI-MS. New strategies for predicting ionization efficiency in silico allow for rapid and semiquantitative analysis of newly discovered biomarkers and/or drug metabolites in metabolomics research when chemical standards do not exist.

Chiral discrimination in biomimetic systems: Phenylalanine

Indian Academy of Sciences (India)

WINTEC

dihedral angle to locate the minimum energy conformation using quantum chemical theory. We com- pared the intermolecular energy surfaces of phenyl alanine molecule in its neutral and zwitterionic state ... sub-units like amino acids in protein remained a puzzle. ... non-bonded and electrostatic interaction between.

Rapid, Efficient and Versatile Strategies for Functionally Sophisticated Polymers and Nanoparticles: Degradable Polyphosphoesters and Anisotropic Distribution of Chemical Functionalities

Science.gov (United States)

Zhang, Shiyi

conjugate by densely attaching the polyphosphoester block with azide-functionalized Paclitaxel by azide-alkyne Huisgen cycloaddition. This Paclitaxel drug conjugate provides a powerful platform for combinational cancer therapy and bioimaging due to its ultra-high Paclitaxel loading (> 65 wt%), high water solubility (>6.2 mg/mL for PTX) and easy functionalization. Another polyphosphoester-based nanoparticle system has been developed by a programmable process for the rapid and facile preparation of a family of nanoparticles with different surface charges and functionalities. The non-ionic, anionic, cationic and zwitterionic nanoparticles with hydrodynamic diameters between 13 nm to 21 nm and great size uniformity could be rapidly prepared from small molecules in 6 h or 2 days. The anionic and zwitterionic nanoparticles were designed to load silver ions to treat pulmonary infections, while the cationic nanoparticles are being applied to regulate lung injuries by serving as a degradable iNOS inhibitor conjugates. In addition, a direct synthesis of acid-labile polyphosphoramidate by organobase-catalyzed ring-opening polymerization and an improved two-step preparation of polyphosphoester ionomer by acid-assisted cleavage of phosphoramidate bonds on polyphosphoramidate were developed. Polyphosphoramidate and polyphosphoester ionomers may be applied to many applications, due to their unique chemical and physical properties.

Thermodynamics and Structural Evolution during a Reversible Vesicle-Micelle Transition of a Vitamin-Derived Bolaamphiphile Induced by Sodium Cholate.

Science.gov (United States)

Tian, Jun-Nan; Ge, Bing-Qiang; Shen, Yun-Feng; He, Yu-Xuan; Chen, Zhong-Xiu

2016-03-09

Interaction of endogenous sodium cholate (SC) with dietary amphiphiles would induce structural evolution of the self-assembled aggregates, which inevitably affects the hydrolysis of fat in the gut. Current work mainly focused on the interaction of bile salts with classical double-layered phospholipid vesicles. In this paper, the thermodynamics and structural evolution during the interaction of SC with novel unilamellar vesicles formed from vitamin-derived zwitterionic bolaamphiphile (DDO) were characterized. It was revealed that an increased temperature and the presence of NaCl resulted in narrowed micelle-vesicle coexistence and enlarged the vesicle region. The coexistence of micelles and vesicles mainly came from the interaction of monomeric SC with DDO vesicles, whereas micellar SC contributed to the total solubilization of DDO vesicles. This research may enrich the thermodynamic mechanism behind the structure transition of the microaggregates formed by amphiphiles in the gut. It will also contribute to the design of food formulation and drug delivery system.

Lethal and mutagenic effects of radiation and chemicals on cultured fish cells derived the erythrophoroma of goldfish (Carassius auratus)

Energy Technology Data Exchange (ETDEWEB)

Mitani, H. (Tokyo Univ. (Japan). Inst. of Zoology)

1983-01-01

GEM 199 cells derived from an eryhtrophoroma of goldfish (Carassius auratus), which had a high plating efficiency, were used to investigate the lethal and mutational effects of radiations (UV and ..gamma..-rays) and chemicals (4NQO and MNNG). The cells were more resistant to rays than mammalian cells and CAF-MM1 cells derived from the normal fin tissue of goldfish. They were also more resistant to UV-irradiation than CAF-MM1 cells. Photoreactivation after UV-irradiation was present in GEM 199 cells for both survival and mutation. The initial shoulder of the survival curve of UV-irradiated cells was reduced greatly by caffeine, suggesting a high activity of the post-replication repair. The spontaneous mutation frequency to ouabain resistance was 1-5x10/sup -6/ clones per viable cell. MNNG was effective in inducing ouabain-resistant mutation, while 4NQO and ..gamma..-rays did not induce mutation.

Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering

International Nuclear Information System (INIS)

Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Rigogliuso, Salvatrice; Ghersi, Giulio; Giammona, Gaetano

2013-01-01

In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. - Highlights: ► Hyaluronic acid (HA) has been functionalized with ethylenediamine (EDA). ► Amino groups of HA-EDA allow the reaction with α-elastin and ethylene glycol diglycidyl ether (EGDGE). ► Chemical scaffolds of HA-EDA-graft-α-elastin/EGDGE have been characterized. ► The presence of α-elastin affects porosity, swelling and enzymatic degradation of scaffolds. ► The presence of α-elastin improves attachment, viability and proliferation of fibroblasts and smooth muscle cells

Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Palumbo, Fabio Salvatore [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); Pitarresi, Giovanna, E-mail: giovanna.pitarresi@unipa.it [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); Institute of Biophysics at Palermo, Italian National Research Council, Via Ugo La Malfa 153, 90146 Palermo (Italy); Fiorica, Calogero [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); Rigogliuso, Salvatrice; Ghersi, Giulio [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Biologia Cellulare, Università degli Studi di Palermo, Viale delle Scienze ed. 16, 90128, Palermo (Italy); Giammona, Gaetano [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); IBIM-CNR, Via Ugo La Malfa 153, 90146 Palermo (Italy)

2013-07-01

In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. - Highlights: ► Hyaluronic acid (HA) has been functionalized with ethylenediamine (EDA). ► Amino groups of HA-EDA allow the reaction with α-elastin and ethylene glycol diglycidyl ether (EGDGE). ► Chemical scaffolds of HA-EDA-graft-α-elastin/EGDGE have been characterized. ► The presence of α-elastin affects porosity, swelling and enzymatic degradation of scaffolds. ► The presence of α-elastin improves attachment, viability and proliferation of fibroblasts and smooth muscle cells.

Critical micelle concentration values for different surfactants measured with solid-phase microextraction fibers

NARCIS (Netherlands)

Haftka, Joris J H; Scherpenisse, Peter; Oetter, G??nter; Hodges, Geoff; Eadsforth, Charles V.; Kotthoff, Matthias; Hermens, Joop L M

The amphiphilic nature of surfactants drives the formation of micelles at the critical micelle concentration (CMC). Solid-phase microextraction (SPME) fibres were used in the present study to measure CMC values of twelve nonionic, anionic, cationic and zwitterionic surfactants. The SPME derived CMC

Fatty acid-derived biofuels and chemicals production in Saccharomyces cerevisiae

Directory of Open Access Journals (Sweden)

Yongjin J. Zhou

2014-09-01

Full Text Available Volatile energy costs and environmental concerns have spurred interest in the development of alternative, renewable, sustainable and cost-effective energy resources. Advanced biofuels have potential to replace fossil fuels in supporting high-power demanding machinery such as aircrafts and trucks. Microbial biosynthesis is generally considered as an environmental friendly refinery process, and fatty acid biosynthesis is an attractive route to synthesize chemicals and especially drop-in biofuels due to the high degree of reduction of fatty acids. The robustness and excellent accessibility to molecular genetics make the yeast S. cerevisiae a suitable host for the production of biofuels, chemicals and pharmaceuticals, and recent advances in metabolic engineering as well as systems and synthetic biology allow us to engineer the yeast fatty acid metabolism and modification pathways for production of advanced biofuels and chemicals.

Acute toxicity of chemical pesticides and plant-derived essential oil on the behavior and development of earthworms, Eudrilus eugeniae (Kinberg) and Eisenia fetida (Savigny).

Science.gov (United States)

Vasantha-Srinivasan, Prabhakaran; Senthil-Nathan, Sengottayan; Ponsankar, Athirstam; Thanigaivel, Annamalai; Chellappandian, Muthiah; Edwin, Edward-Sam; Selin-Rani, Selvaraj; Kalaivani, Kandaswamy; Hunter, Wayne B; Duraipandiyan, Veeramuthu; Al-Dhabi, Naif Abdullah

2018-04-01

Comparative toxicity of two chemical pesticides (temephos and monocrotophos) versus a plant-derived betel leaf oil Piper betle (L.) to earthworm Eudrilus eugeniae (Kinberg) and redworm Eisenia fetida Savigny, historically: Eisenia foetida (Savigny 1826), was evaluated. Mortality rate was more prominent in temephos at 100 μg concentration to both the earthworms in filter paper test (FPT) as well as 10 mg concentration in artificial soil test (AST). In contrast, P. betle does not display much mortality rate to both the earthworms even at 1000 mg of treatment concentrations. The lethal concentration (LC 50 ) value was observed at 3.89 and 5.26 mg/kg for temephos and monocrotophos against E. eugeniae and 3.81 and 5.25 mg/kg to E. fetida, respectively. Whereas, LC 50 value of betel leaf oil was only observed at 3149 and 4081 mg/kg to E. eugeniae and E. fetida, respectively. Correspondingly, the avoidance or attraction assay also displayed that earthworms were more sensitive to the soil containing chemical pesticides. Whereas, the avoidance percentage was decreased in the P. betle oil. Similarly, sublethal concentration of chemical pesticides (5 and 6.5 mg) significantly reduced the earthworm weight and growth rate. However, P. betle oil did not change the developmental rate in the duration of the assay (2, 7 and 14 days) even at 4000 mg treatment concentration. The enzyme ratio of CAT and SOD was also affected significantly after exposure to the chemical pesticides (6.5 mg/kg). Hence, our study implied the risk assessment associated with the chemical pesticides and also recommends plant-derived harmless P. betle oil against beneficial species as an alternative pest control agent.

Minocycline and doxycycline, but not other tetracycline-derived compounds, protect liver cells from chemical hypoxia and ischemia/reperfusion injury by inhibition of the mitochondrial calcium uniporter

International Nuclear Information System (INIS)

Schwartz, Justin; Holmuhamedov, Ekhson; Zhang, Xun; Lovelace, Gregory L.; Smith, Charles D.; Lemasters, John J.

2013-01-01

Minocycline, a tetracycline-derived compound, mitigates damage caused by ischemia/reperfusion (I/R) injury. Here, 19 tetracycline-derived compounds were screened in comparison to minocycline for their ability to protect hepatocytes against damage from chemical hypoxia and I/R injury. Cultured rat hepatocytes were incubated with 50 μM of each tetracycline-derived compound 20 min prior to exposure to 500 μM iodoacetic acid plus 1 mM KCN (chemical hypoxia). In other experiments, hepatocytes were incubated in anoxic Krebs–Ringer–HEPES buffer at pH 6.2 for 4 h prior to reoxygenation at pH 7.4 (simulated I/R). Tetracycline-derived compounds were added 20 min prior to reperfusion. Ca 2+ uptake was measured in isolated rat liver mitochondria incubated with Fluo-5N. Cell killing after 120 min of chemical hypoxia measured by propidium iodide (PI) fluorometry was 87%, which decreased to 28% and 42% with minocycline and doxycycline, respectively. After I/R, cell killing at 120 min decreased from 79% with vehicle to 43% and 49% with minocycline and doxycycline. No other tested compound decreased killing. Minocycline and doxycycline also inhibited mitochondrial Ca 2+ uptake and suppressed the Ca 2+ -induced mitochondrial permeability transition (MPT), the penultimate cause of cell death in reperfusion injury. Ru360, a specific inhibitor of the mitochondrial calcium uniporter (MCU), also decreased cell killing after hypoxia and I/R and blocked mitochondrial Ca 2+ uptake and the MPT. Other proposed mechanisms, including mitochondrial depolarization and matrix metalloprotease inhibition, could not account for cytoprotection. Taken together, these results indicate that minocycline and doxycycline are cytoprotective by way of inhibition of MCU. - Highlights: • Minocycline and doxycycline are the only cytoprotective tetracyclines of those tested • Cytoprotective tetracyclines inhibit the MPT and mitochondrial calcium and iron uptake. • Cytoprotective tetracyclines protect

Minocycline and doxycycline, but not other tetracycline-derived compounds, protect liver cells from chemical hypoxia and ischemia/reperfusion injury by inhibition of the mitochondrial calcium uniporter

Energy Technology Data Exchange (ETDEWEB)

Schwartz, Justin; Holmuhamedov, Ekhson; Zhang, Xun; Lovelace, Gregory L.; Smith, Charles D. [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC (United States); Lemasters, John J., E-mail: JJLemasters@musc.edu [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC (United States); Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC (United States)

2013-11-15

Minocycline, a tetracycline-derived compound, mitigates damage caused by ischemia/reperfusion (I/R) injury. Here, 19 tetracycline-derived compounds were screened in comparison to minocycline for their ability to protect hepatocytes against damage from chemical hypoxia and I/R injury. Cultured rat hepatocytes were incubated with 50 μM of each tetracycline-derived compound 20 min prior to exposure to 500 μM iodoacetic acid plus 1 mM KCN (chemical hypoxia). In other experiments, hepatocytes were incubated in anoxic Krebs–Ringer–HEPES buffer at pH 6.2 for 4 h prior to reoxygenation at pH 7.4 (simulated I/R). Tetracycline-derived compounds were added 20 min prior to reperfusion. Ca{sup 2+} uptake was measured in isolated rat liver mitochondria incubated with Fluo-5N. Cell killing after 120 min of chemical hypoxia measured by propidium iodide (PI) fluorometry was 87%, which decreased to 28% and 42% with minocycline and doxycycline, respectively. After I/R, cell killing at 120 min decreased from 79% with vehicle to 43% and 49% with minocycline and doxycycline. No other tested compound decreased killing. Minocycline and doxycycline also inhibited mitochondrial Ca{sup 2+} uptake and suppressed the Ca{sup 2+}-induced mitochondrial permeability transition (MPT), the penultimate cause of cell death in reperfusion injury. Ru360, a specific inhibitor of the mitochondrial calcium uniporter (MCU), also decreased cell killing after hypoxia and I/R and blocked mitochondrial Ca{sup 2+} uptake and the MPT. Other proposed mechanisms, including mitochondrial depolarization and matrix metalloprotease inhibition, could not account for cytoprotection. Taken together, these results indicate that minocycline and doxycycline are cytoprotective by way of inhibition of MCU. - Highlights: • Minocycline and doxycycline are the only cytoprotective tetracyclines of those tested • Cytoprotective tetracyclines inhibit the MPT and mitochondrial calcium and iron uptake. • Cytoprotective

Production of a refined biooil derived by fast pyrolysis of chicken manure with chemical and physical characteristics close to those of fossil fuels.

Science.gov (United States)

Monreal, Carlos M; Schnitzer, Morris

2011-01-01

The chemical and physical properties of raw biooils prevent their direct use in combustion engines. We processed raw pyrolytic biooil derived from chicken manure to yield a colorless refined biooil with diesel qualities. Chemical characterization of the refined biooil involved elemental and several spectroscopic analyses. The physical measurements employed were viscosity, density and heat of combustion. The elemental composition (% wt/wt) of the refined biooil was 82.7 % C, 15.3 % H, 0.2 % N and 1.8 % O, no S. Its viscosity was 0.006 Pa.s and a heat of combustion of 43 MJ kg(-1). The refined biooil fraction contains n-alkanes, ranging from n-C(14) to n-C(27), alkenes varying from C(10:1) to C(22:1), and long-chain alcohols. The refined biooil makes a good diesel fuel due to its chemical and physical properties.

Facile Chemical Access to Biologically Active Norcantharidin Derivatives from Biomass

Directory of Open Access Journals (Sweden)

Konstantin I. Galkin

2017-12-01

Full Text Available Reductive amination of 2,5-diformylfuran (DFF was used to implement the transition from bio-derived 5-hydroxymethylfurfural (HMF to pharmaceuticals. The synthesized bis(aminomethylfurans were utilized as building blocks for the construction of new derivatives with structural cores of naturally occurring biologically active compounds. Using the one-pot procedure, which included the Diels–Alder reaction followed by hydrogenation of the double bond, bio-derived analogues of the anticancer drug norcantharidin were obtained. The cyclization process was diastereoselective, and resulted in the formation of tricyclic products with the endo configuration. Analysis of cytotoxycity for the resulting tricyclic amine-containing compounds showed an increase of anticancer activity as compared with the unsubstituted norcantharimide.

Synthesis and Some Reactions of 3-Chloro-2-(cyanomethylene-1,2-dihydroquinoxalines

Directory of Open Access Journals (Sweden)

Wolfgang Pfleiderer

2004-03-01

Full Text Available 2,3-Dichloroquinoxaline and some of its derivatives have been reacted with malononitrile and ethyl cyanoacetate to yield a variety of 3-chloro-2-(cyanomethylene- 1,2-dihydroquinoxaline derivatives. The reaction of 3-chloro-2-(dicyanomethylene-1,2- dihydroquinoxaline (2e with pyridine and its methyl derivatives led to the zwitterionic structures 6a-6c. The structures of the newly synthesized compounds were assigned by spectroscopic data and elemental analyses.

Nucleic acid helix structure determination from NMR proton chemical shifts

Energy Technology Data Exchange (ETDEWEB)

Werf, Ramon M. van der; Tessari, Marco; Wijmenga, Sybren S., E-mail: S.Wijmenga@science.ru.nl [Radboud University Nijmegen, Department of Biophysical Chemistry, Institute of Molecules and Materials (Netherlands)

2013-06-15

We present a method for de novo derivation of the three-dimensional helix structure of nucleic acids using non-exchangeable proton chemical shifts as sole source of experimental restraints. The method is called chemical shift de novo structure derivation protocol employing singular value decomposition (CHEOPS) and uses iterative singular value decomposition to optimize the structure in helix parameter space. The correct performance of CHEOPS and its range of application are established via an extensive set of structure derivations using either simulated or experimental chemical shifts as input. The simulated input data are used to assess in a defined manner the effect of errors or limitations in the input data on the derived structures. We find that the RNA helix parameters can be determined with high accuracy. We finally demonstrate via three deposited RNA structures that experimental proton chemical shifts suffice to derive RNA helix structures with high precision and accuracy. CHEOPS provides, subject to further development, new directions for high-resolution NMR structure determination of nucleic acids.

On the isolation of single basic amino acids with electrodialysis for the production of biochemicals

NARCIS (Netherlands)

Kattan Readi, O.M.; Girones nogue, Miriam; Wiratha, W.; Nijmeijer, Dorothea C.

2013-01-01

Amino acids from biobased feeds are an interesting feedstock for the production of biobased chemicals from cheap protein sources, as amino acids already have the required functionalities. Amino acids are zwitterionic molecules whose charge is determined by the surrounding pH. This makes the use of

LLNL Chemical Kinetics Modeling Group

Energy Technology Data Exchange (ETDEWEB)

Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J

2008-09-24

The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.

Hydrophobic, Hydrophilic, and Amphiphilic Polyglycocarbonates with Linear and Macrocyclic Architectures from Bicyclic Glycocarbonates Derived from CO2 and Glucoside

KAUST Repository

Pati, Debasis; Feng, Xiaoshuang; Hadjichristidis, Nikolaos; Gnanou, Yves

2017-01-01

Two bicyclic glycocarbonates were synthesized in five steps from α-methyl-d-glucoside without resorting to phosgene or to its derivatives for the first time. The 4- and 6-positions of glucose were modified to introduce a six-membered carbonate ring, using CO as the carbonylating reagent; the 2- and 3-positions of the same glucoside substrate were first transformed into either methyl or triethylene glycol monomethyl ether groups to protect these positions from undesirable reactions and also to impart hydrophobicity in the first case and hydrophilicity in the second. The polymerization behavior of these bicyclic glycocarbonates was then investigated under different conditions. On the one hand, through ring-opening polymerization of the above monomers, linear polyglycocarbonate homopolymers and diblock copolymers were obtained initiated by p-methylbenzyl alcohol using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst; on the other hand, macrocyclic polyglycocarbonate homopolymers and diblock copolymers were grown using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) which served as zwitterionic initiator. The various architectures derived were all thoroughly characterized by NMR, GPC, and MALDI-tof and shown to exhibit the expected structure. Finally, the self-assembly of linear and macrocyclic amphiphilic copolyglycocarbonates in water was investigated and characterized by cryo-TEM.

Hydrophobic, Hydrophilic, and Amphiphilic Polyglycocarbonates with Linear and Macrocyclic Architectures from Bicyclic Glycocarbonates Derived from CO2 and Glucoside

KAUST Repository

Pati, Debasis

2017-02-09

Two bicyclic glycocarbonates were synthesized in five steps from α-methyl-d-glucoside without resorting to phosgene or to its derivatives for the first time. The 4- and 6-positions of glucose were modified to introduce a six-membered carbonate ring, using CO as the carbonylating reagent; the 2- and 3-positions of the same glucoside substrate were first transformed into either methyl or triethylene glycol monomethyl ether groups to protect these positions from undesirable reactions and also to impart hydrophobicity in the first case and hydrophilicity in the second. The polymerization behavior of these bicyclic glycocarbonates was then investigated under different conditions. On the one hand, through ring-opening polymerization of the above monomers, linear polyglycocarbonate homopolymers and diblock copolymers were obtained initiated by p-methylbenzyl alcohol using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst; on the other hand, macrocyclic polyglycocarbonate homopolymers and diblock copolymers were grown using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) which served as zwitterionic initiator. The various architectures derived were all thoroughly characterized by NMR, GPC, and MALDI-tof and shown to exhibit the expected structure. Finally, the self-assembly of linear and macrocyclic amphiphilic copolyglycocarbonates in water was investigated and characterized by cryo-TEM.

Development of a pluripotent stem cell derived neuronal model to identify chemically induced pathway perturbations in relation to neurotoxicity: Effects of CREB pathway inhibition

Energy Technology Data Exchange (ETDEWEB)

Pistollato, Francesca; Louisse, Jochem; Scelfo, Bibiana; Mennecozzi, Milena [Institute for Health and Consumer Protection (IHCP), JRC, Ispra (Italy); Accordi, Benedetta; Basso, Giuseppe [Oncohematology Laboratory, Department of Woman and Child Health, University of Padova, Padova (Italy); Gaspar, John Antonydas [Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne, Cologne (Germany); Zagoura, Dimitra; Barilari, Manuela; Palosaari, Taina [Institute for Health and Consumer Protection (IHCP), JRC, Ispra (Italy); Sachinidis, Agapios [Center of Physiology and Pathophysiology, Institute of Neurophysiology, University of Cologne, Cologne (Germany); Bremer-Hoffmann, Susanne, E-mail: susanne.bremer@jrc.ec.europa.eu [Institute for Health and Consumer Protection (IHCP), JRC, Ispra (Italy)

2014-10-15

According to the advocated paradigm shift in toxicology, acquisition of knowledge on the mechanisms underlying the toxicity of chemicals, such as perturbations of biological pathways, is of primary interest. Pluripotent stem cells (PSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer a unique opportunity to derive physiologically relevant human cell types to measure molecular and cellular effects of such pathway modulations. Here we compared the neuronal differentiation propensity of hESCs and hiPSCs with the aim to develop novel hiPSC-based tools for measuring pathway perturbation in relation to molecular and cellular effects in vitro. Among other fundamental pathways, also, the cAMP responsive element binding protein (CREB) pathway was activated in our neuronal models and gave us the opportunity to study time-dependent effects elicited by chemical perturbations of the CREB pathway in relation to cellular effects. We show that the inhibition of the CREB pathway, using 2-naphthol-AS-E-phosphate (KG-501), induced an inhibition of neurite outgrowth and synaptogenesis, as well as a decrease of MAP2{sup +} neuronal cells. These data indicate that a CREB pathway inhibition can be related to molecular and cellular effects that may be relevant for neurotoxicity testing, and, thus, qualify the use of our hiPSC-derived neuronal model for studying chemical-induced neurotoxicity resulting from pathway perturbations. - Highlights: • HESCs derived neuronal cells serve as benchmark for iPSC based neuronal toxicity test development. • Comparisons between hESCs and hiPSCs demonstrated variability of the epigenetic state • CREB pathway modulation have been explored in relation to the neurotoxicant exposure KG-501 • hiPSC might be promising tools to translate theoretical AoPs into toxicological in vitro tests.

Physico-Chemical and Structural Interpretation of Discrete Derivative Indices on N-Tuples Atoms

Directory of Open Access Journals (Sweden)

Oscar Martínez-Santiago

2016-05-01

Full Text Available This report examines the interpretation of the Graph Derivative Indices (GDIs from three different perspectives (i.e., in structural, steric and electronic terms. It is found that the individual vertex frequencies may be expressed in terms of the geometrical and electronic reactivity of the atoms and bonds, respectively. On the other hand, it is demonstrated that the GDIs are sensitive to progressive structural modifications in terms of: size, ramifications, electronic richness, conjugation effects and molecular symmetry. Moreover, it is observed that the GDIs quantify the interaction capacity among molecules and codify information on the activation entropy. A structure property relationship study reveals that there exists a direct correspondence between the individual frequencies of atoms and Hückel’s Free Valence, as well as between the atomic GDIs and the chemical shift in NMR, which collectively validates the theory that these indices codify steric and electronic information of the atoms in a molecule. Taking in consideration the regularity and coherence found in experiments performed with the GDIs, it is possible to say that GDIs possess plausible interpretation in structural and physicochemical terms.

Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

International Nuclear Information System (INIS)

Franco-Pérez, Marco; Gázquez, José L.; Ayers, Paul W.; Vela, Alberto

2015-01-01

We extend the definition of the electronic chemical potential (μ e ) and chemical hardness (η e ) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μ e . Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (−I), positive (−A), and zero values of the fractional charge (−(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness

Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

Science.gov (United States)

Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

2015-12-01

Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 μg/L for nitrated and 0.3-8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Implications of surface charge and curvature for the binding orientation of Thermomyces lanuginosus lipase on negatively charged or zwitterionic phospholipid vesicles as studied by ESR spectroscopy

DEFF Research Database (Denmark)

Hedin, E.M.K.; Høyrup, Lise Pernille Kristine; Patkar, S.A.

2005-01-01

fluorescence quenching efficiency between each spin-label positioned on TLL, and the lipid membrane. ESR exposure and fluorescence quenching data show that TILL associates closer to the negatively charged PG surface than the zwitterionic PC surface, and binds to both POPG LUV and POPC SUV predominantly through......The triglyceride lipase (EC 3.1.1.3) Thermomyces lanuginosus lipase (TLL) binds with high affinity to unilamellar phospholipid vesicles that serve as a diluent interface for both lipase and substrate, but it displays interfacial activation on only small and negatively charged such vesicles [Cajal......) spectroscopy in combination with site-directed spin-labeling [Hedin, E. M. K., et al. (2002) Biochemistry 41, 1418514196]. In our investigation, we have studied the interfacial orientation of TLL when bound to large unilamellar vesicles (LUV) consisting of POPG, and bound to SUV consisting of 1-palmitoyl-2...

Comparison of zwitterionic N-alkylaminomethanesulfonic acids to related compounds in the Good buffer series

Directory of Open Access Journals (Sweden)

Robert D. Long

2010-04-01

Full Text Available Several N-alkyl and N,N-dialkylaminomethanesulfonic acids were synthesized (as zwitterions and/or sodium salts to be tested for utility as biological buffers at lower pH levels than existing Good buffer compounds (aminoalkanesulfonates with a minimum of two carbons between amine and sulfonic acid groups as originally described by Norman Good, and in common use as biological buffers. Our hypothesis was that a shorter carbon chain (one carbon between the amino and sulfonic acid groups should lower the ammonium ion pKa values. The alkylaminomethanesulfonate compounds were synthesized in aqueous solution by reaction of primary or secondary amines with formaldehyde/sodium hydrogensulfite addition compound. The pKa values of the ammonium ions of this series of compounds (compared to existing Good buffers was found to correlate well with the length of the carbon chain between the amino and sulfonate moeties, with a significant decrease in amine basicity in the aminomethanesulfonate compounds (pKa decrease of 2 units or more compared to existing Good buffers. An exception was found for the 2-hydroxypiperazine series which shows only a small pKa decrease, probably due to the site of protonation in this compound (as confirmed by X-ray crystal structure. X-ray crystallographic structures of two members of the series are reported. Several of these compounds have pKa values that would indicate potential utility for buffering at pH levels below the normal physiological range (pKa values in the range of 3 to 6 without aqueous solubility problems – a range that is problematic for currently available Good buffers. Unfortunately, the alkylaminomethanesulfonates were found to degrade (with loss of their buffering ability at pH levels below the pKa value and were unstable at elevated temperature (as when autoclaving – thus limiting their utility.

Chemical thermodynamics. An introduction

Energy Technology Data Exchange (ETDEWEB)

Keszei, Ernoe [Budapest Univ. (Hungary). Dept. of Physical Chemistry

2012-07-01

Eminently suitable as a required textbook comprising complete material for or an undergraduate chemistry major course in chemical thermodynamics. Clearly explains details of formal derivations that students can easily follow and so master applied mathematical operations. Offers problems and solutions at the end of each chapter for self-test and self- or group study. This course-derived undergraduate textbook provides a concise explanation of the key concepts and calculations of chemical thermodynamics. Instead of the usual 'classical' introduction, this text adopts a straightforward postulatory approach that introduces thermodynamic potentials such as entropy and energy more directly and transparently. Structured around several features to assist students' understanding, Chemical Thermodynamics: - Develops applications and methods for the ready treatment of equilibria on a sound quantitative basis. - Requires minimal background in calculus to understand the text and presents formal derivations to the student in a detailed but understandable way. - Offers end-of-chapter problems (and answers) for self-testing and review and reinforcement, of use for self- or group study. This book is suitable as essential reading for courses in a bachelor and master chemistry program and is also valuable as a reference or textbook for students of physics, biochemistry and materials science.

Carpatizine, a novel bridged oxazine derivative generated by non-enzymatic reactions.

Science.gov (United States)

Fu, Peng; MacMillan, John B

2017-06-27

Carpatizine (1), a new bridged oxazine derivative, was isolated from a marine-derived Streptomyces strain SNE-011. The structure was fully determined by spectroscopic analysis, ECD calculations and chemical methods. A plausible non-enzymatic reaction mechanism from daryamide D leading to carpatizine was presented, which was confirmed by chemical transformation.

Characterisation of waste derived biochar added biocomposites: chemical and thermal modifications

Energy Technology Data Exchange (ETDEWEB)

Das, Oisik [Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142 (New Zealand); Sarmah, Ajit K., E-mail: a.sarmah@auckland.ac.nz [Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142 (New Zealand); Zujovic, Zoran [School of Chemical Sciences, University of Auckland, Auckland 1142 (New Zealand); Bhattacharyya, Debes [Centre for Advanced Composite Materials, Department of Mechanical Engineering, University of Auckland, Auckland 1142 (New Zealand)

2016-04-15

A step towards sustainability was taken by incorporating waste based pyrolysed biochar in wood and polypropylene biocomposites. The effect of biochar particles on the chemistry and thermal makeup of the composites was determined by characterising them through an array of characterisation techniques such as 3D optical profiling, X-ray diffraction, transmission electron microscopy, electron spin/nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. It was observed that addition of biochar increased the presence of free radicals in the composite while also improving its thermal conductivity. Biochar particles did not interfere with the melting behaviour of polymer in the thermal regime. However, wood and biochar acted as nucleation agents consequently increasing the crystallisation temperature. The crystal structure of polypropylene was not disrupted by biochar inclusion in composite. Transmission electron microscopy images illustrated the aggregated nature of the biochar particles at higher loading levels. Nuclear magnetic resonance studies revealed the aromatic nature of biochar and the broadening of peak intensities of composites with increasing biochar levels due to its amorphous nature and presence of free radicals. Thus, this insight into the chemical and thermal modification of biochar added composites would allow effective engineering to optimise their properties while simultaneously utilising wastes. - Highlights: • Waste derived biochars were used to make polymer based biocomposites. • Composites were characterised by NMR, ESR, DSC, XRD, TEM etc. • Biochar increased the thermal conductivity of composites. • Biochar did not disrupt the crystal structure of polypropylene. • NMR revealed aromatic nature of biochar in composites.

Characterisation of waste derived biochar added biocomposites: chemical and thermal modifications

International Nuclear Information System (INIS)

Das, Oisik; Sarmah, Ajit K.; Zujovic, Zoran; Bhattacharyya, Debes

2016-01-01

A step towards sustainability was taken by incorporating waste based pyrolysed biochar in wood and polypropylene biocomposites. The effect of biochar particles on the chemistry and thermal makeup of the composites was determined by characterising them through an array of characterisation techniques such as 3D optical profiling, X-ray diffraction, transmission electron microscopy, electron spin/nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. It was observed that addition of biochar increased the presence of free radicals in the composite while also improving its thermal conductivity. Biochar particles did not interfere with the melting behaviour of polymer in the thermal regime. However, wood and biochar acted as nucleation agents consequently increasing the crystallisation temperature. The crystal structure of polypropylene was not disrupted by biochar inclusion in composite. Transmission electron microscopy images illustrated the aggregated nature of the biochar particles at higher loading levels. Nuclear magnetic resonance studies revealed the aromatic nature of biochar and the broadening of peak intensities of composites with increasing biochar levels due to its amorphous nature and presence of free radicals. Thus, this insight into the chemical and thermal modification of biochar added composites would allow effective engineering to optimise their properties while simultaneously utilising wastes. - Highlights: • Waste derived biochars were used to make polymer based biocomposites. • Composites were characterised by NMR, ESR, DSC, XRD, TEM etc. • Biochar increased the thermal conductivity of composites. • Biochar did not disrupt the crystal structure of polypropylene. • NMR revealed aromatic nature of biochar in composites.

Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

Energy Technology Data Exchange (ETDEWEB)

Franco-Pérez, Marco, E-mail: qimfranco@hotmail.com, E-mail: jlgm@xanum.uam.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México D. F. 09340 (Mexico); Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Gázquez, José L., E-mail: qimfranco@hotmail.com, E-mail: jlgm@xanum.uam.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México D. F. 09340 (Mexico); Ayers, Paul W. [Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Vela, Alberto [Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), Av. Instituto Politécnico Nacional 2508, México D. F. 07360 (Mexico)

2015-10-21

We extend the definition of the electronic chemical potential (μ{sub e}) and chemical hardness (η{sub e}) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μ{sub e}. Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (−I), positive (−A), and zero values of the fractional charge (−(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness.

Structural diversity of three Cu(II) compounds based on a new tripodal zwitterionic ligand: Syntheses, structures and properties

Science.gov (United States)

Zhou, Jie; Zhao, Jing-Song; Feng, Jing; Zhang, Xiao-Feng; Xu, Jian; Du, Lin; Xie, Ming-Jin; Zhao, Qi-Hua

2018-03-01

An exploration of reactions of 1,1‧,1″-(benzene-1,3,5-triyltris(methylene))tris(4-carboxypyridinium)-tribromide (H3LBr3) with Cu(II) salt under different pH conditions has led to the formation of three complexes, [Cu(HL)2(H2O)3]·4(ClO4)·3H2O (1), [Cu2(HL)(μ3-OH)(μ2-H2O)(H2O)2]·4(ClO4)·6H2O (2), and [Cu3(L)2Cl6(H2O)4]·4H2O (3). Single-crystal X-ray analyses revealed that complex 1 displays a discrete mononuclear structure with the ligand in a bowl-shaped configuration. Complex 2 possesses a tetranuclear 1D beaded chain structure. While complex 3 features a discrete trinuclear 'H-type' structure with the ligand in a chair-like configuration. The distinct compositions and structures of 1-3 are mainly ascribed to the different pH values of the reaction solution, the influences of anions, as well as the configurations which the zwitterion ligands adopt. The magnetic properties of 2, and the photoluminescence properties of 2, and 3 have been investigated. Moreover, powder X-ray diffraction, infrared spectroscopy, and elemental analysis were also performed.

Development of chitosan derivatives with anhydride maleic

International Nuclear Information System (INIS)

Silva, Solranny C.C.C.; Braz, Elton Marks de A.; Brito, Carla Adriana R. de S.; Silva, Durcilene A. da; Junior, Luiz de S.S.; Silva Filho, Edson C. da

2015-01-01

Chitosan was chemically modified with maleic anhydride in ratios of 1/2, 1/5 and 1/10 in the absence of solvents. The obtained derivatives were characterized by elemental analysis, FTIR, thermal analysis (TGA / DTG) and XRD where it was possible to prove the chemical modification. Elemental analysis showed an increase of the relation C / N with the increasing of the proportion of anhydrides. The FTIR showed the incorporation of the anhydride in the biopolymer structure. The thermal stability of the derivatives was lower in comparison to the polysaccharide and by XRD the modified materials were less crystalline. (author)

Indium tin oxide with zwitterionic interfacial design for biosensing applications in complex matrices

Science.gov (United States)

Darwish, Nadia T.; Alias, Yatimah; Khor, Sook Mei

2015-01-01

Biosensing interfaces consisting of linker molecules (COOH or NH2) and charged, antifouling moieties ((sbnd SO3- and N+(Me)3) for biosensing applications were prepared for the first time by the in situ deposition of mixtures of aryl diazonium cations on indium tin oxide (ITO) electrodes. A linker molecule is required for the attachment of biorecognition molecules (e.g., antibodies, enzymes, DNA chains, and aptamers) close to the transducer surface. The attached molecules improve the biosensing sensitivity and also provide a short response time for analyte detection. Thus, the incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. The reductive adsorption behavior and electrochemical measurement were studied for (1) an individual compound and (2) a mixture of antifouling zwitterionic molecules together with linker molecules [combination 1: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 1,4-phenylenediamine (PPD); combination 2: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 4-aminobenzoic acid (PABA)] of aryl diazonium cations grafted onto an ITO electrode. The mixture ratios of SP:TMAP:PPD and SP:TMAP:PABA that provided the greatest resistance to non-specific protein adsorptions of bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC) and cytochrome c labeled with rhodamine B isothiocyanate (RBITC-Cyt c) were determined by confocal laser scanning microscopy (CLSM). For the surface antifouling study, we used 2-[2-(2-methoxyethoxy) ethoxy]acetic acid (OEG) as a standard control because of its prominent antifouling properties. Surface compositions of combinations 1 and 2 were characterized using X-ray photoelectron spectroscopy (XPS). Field-emission scanning electron microscopy (FE-SEM) was used to characterize the morphology of the grafted films to confirm the even distribution between linker and antifouling molecules grafted onto the ITO surfaces

Protein Structure Validation and Refinement Using Chemical Shifts Derived from Quantum Mechanics

DEFF Research Database (Denmark)

Bratholm, Lars Andersen

to within 3 A. Furthermore, a fast quantum mechanics based chemical shift predictor was developed together with methodology for using chemical shifts in structure simulations. The developed predictor was used for renement of several protein structures and for reducing the computational cost of quantum...... mechanics / molecular mechanics (QM/MM) computations of chemical shieldings. Several improvements to the predictor is ongoing, where among other things, kernel based machine learning techniques have successfully been used to improve the quantum mechanical level of theory used in the predictions....

Synthesis of Renewable meta-Xylylenediamine from Biomass-Derived Furfural.

Science.gov (United States)

Scodeller, Ivan; Mansouri, Samir; Morvan, Didier; Muller, Eric; de Oliveira Vigier, Karine; Wischert, Raphael; Jérôme, François

2018-04-30

We report the synthesis of biomass-derived functionalized aromatic chemicals from furfural, a building block nowadays available in large scale from low-cost biomass. The scientific strategy relies on a Diels-Alder/aromatization sequence. By controlling the rate of each step, it was possible to produce exclusively the meta aromatic isomer. In particular, through this route, we describe the synthesis of renewably sourced meta-xylylenediamine (MXD). Transposition of this work to other furfural-derived chemicals is also discussed and reveals that functionalized biomass-derived aromatics (benzaldehyde, benzylamine, etc.) can be potentially produced, according to this route. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of radiolabelled aryl azides from diazonium salts: experimental and computational results permit the identification of the preferred mechanism.

Science.gov (United States)

Joshi, Sameer M; de Cózar, Abel; Gómez-Vallejo, Vanessa; Koziorowski, Jacek; Llop, Jordi; Cossío, Fernando P

2015-05-28

Experimental and computational studies on the formation of aryl azides from the corresponding diazonium salts support a stepwise mechanism via acyclic zwitterionic intermediates. The low energy barriers associated with both transition structures are compatible with very fast and efficient processes, thus making this method suitable for the chemical synthesis of radiolabelled aryl azides.

Organometallic derivatives of furan. LII. Synthesis of carbofunctional furylsilanes and their 1H, 13C, and 29Si NMR spectroscopic and quantum-chemical investigation

International Nuclear Information System (INIS)

Lukevits, E.; Erchak, N.P.; Castro, I.; Popelis, Yu.Yu.; Kozyrev, A.K.; Anoshkin, V.I.; Kovalev, I.F.

1986-01-01

Under the standard conditions for the synthesis of furan compounds it is possible to obtain the carbofunctional derivatives of silylated furfural with retention of the trimethylsilyl group in the ring. By NMR and CNDO/2 LCAO MO methods and also as a result of the investigation of the chemical characteristics of silylated furfural and its carbofunctional derivatives it was established that the introduction of a trimethylsilyl group at position 5 of the furan ring does not change the reactivity of the carbofunctional substituents at position 2. The electronic effects of the substituents are hardly transmitted through the furan ring at all. The effect of substituents in the carbofunctional furylsilanes on the electronic structure of the ring is additive

Chemical modification of silica gel with synthesized Schiff base hydrazone derivative and application for preconcentration and separation of U(VI) ions from aqueous solutions

International Nuclear Information System (INIS)

Gamze Karayel Incili; Gul Asiye Aycik

2014-01-01

Schiff base hydrazone derivative (HL) sorbent was synthesized according to the literature to be used in the adsorption and preconcentration of U(VI) ions from aqueous solution and it was exposed to immobilization, and new solid support material was obtained. For this purpose, Schiff base hydrazone derivative (HL) was chemically bonded to silica gel surface immobilized 3-aminopropyl trimethoxysilane, then analyzed by Fourier transform infrared, Brunauer-Emmett-Teller, scanning electron microscopy and elemental analysis. The influence of the solution pH, amount of sorbent, contact time, temperature, foreign ion effect and initial U(VI) concentration was investigated. The maximum U(VI) uptake capacity was found to be 8.46 mg/g. (author)

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Maheswaran Shanmugam. Articles written in Journal of Chemical Sciences. Volume 126 Issue 5 September 2014 pp 1443-1449 Special issue on Chemical Crystallography. Synthesis and magnetic properties of a 1-D helical chain derived from a Nickel-Sodium Schiff base ...

A Proposed Computed Tomography Contrast Agent Using Carboxybetaine Zwitterionic Tantalum Oxide Nanoparticles: Imaging, Biological, and Physicochemical Performance.

Science.gov (United States)

FitzGerald, Paul F; Butts, Matthew D; Roberts, Jeannette C; Colborn, Robert E; Torres, Andrew S; Lee, Brian D; Yeh, Benjamin M; Bonitatibus, Peter J

2016-12-01

The aim of this study was to produce and evaluate a proposed computed tomography (CT) contrast agent based on carboxybetaine zwitterionic (CZ)-coated soluble tantalum oxide (TaO) nanoparticles (NPs). We chose tantalum to provide superior imaging performance compared with current iodine-based clinical CT contrast agents. We developed the CZ coating to provide biological and physical performance similar to that of current iodinated contrast agents. In addition, the aim of this study was to evaluate the imaging, biological, and physicochemical performance of this proposed contrast agent compared with clinically used iodinated agents. We evaluated CT imaging performance of our CZ-TaO NPs compared with that of an iodinated agent in live rats, imaged centrally located within a tissue-equivalent plastic phantom that simulated a large patient. To evaluate vascular contrast enhancement, we scanned the rats' great vessels at high temporal resolution during and after contrast agent injection. We performed several in vivo CZ-TaO NP studies in healthy rats to evaluate tolerability. These studies included injecting the agent at the anticipated clinical dose (ACD) and at 3 times and 6 times the ACD, followed by longitudinal hematology to assess impact to blood cells and organ function (from 4 hours to 1 week). Kidney histological analysis was performed 48 hours after injection at 3 times the ACD. We measured the elimination half-life of CZ-TaO NPs from blood, and we monitored acute kidney injury biomarkers with a kidney injury assay using urine collected from 4 hours to 1 week. We measured tantalum retention in individual organs and in the whole carcass 48 hours after injection at ACD. Carboxybetaine zwitterionic TaO NPs were synthesized and analyzed in detail. We used multidimensional nuclear magnetic resonance to determine surface functionality of the NPs. We measured NP size and solution properties (osmolality and viscosity) of the agent over a range of tantalum concentrations

Iodinated derivatives of vasoactive intestinal peptide (VIP), PHI and PHM: purification, chemical characterization and biological activity

International Nuclear Information System (INIS)

McMaster, D.; Suzuki, Y.; Rorstad, O.; Lederis, K.

1987-01-01

The iodination of vasoactive intestinal peptide (VIP) was studied, using a variety of enzymatic and chemical iodination methods. Reversed phase high performance liquid chromatography (HPLC) was used to purify the reaction products. The lactoperoxidase-glucose oxidase method gave excellent results in terms of reproducibility, iodine incorporation, and yield of the non-oxidized products [Tyr(I)10]VIP and [Tyr(I)22]VIP, and was used to prepare both 125 I and 127 I labelled derivatives. In both cases, direct application to HPLC and a single column system were used. Although the oxidized peptides [Tyr(I)10,Met(O)17]VIP and [Tyr(I)22,Met(O)17]VIP could be generated to varying degrees directly by iodination of VIP, these were most conveniently prepared by iodination of [Met(O)17]VIP. Iodinated derivatives of the homologous peptides PHI and PHM were likewise prepared by rapid, one-step HPLC procedures. The site and degree of iodination were determined by HPLC peptide mapping of tryptic digests and amino acid analyses, and in the case of [Tyr(I)10]VIP also by sequencing. The vasorelaxant activities of the iodinated peptides in bovine cerebral artery preparations did not differ significantly from those of the corresponding noniodinated peptides, with the exception of [Tyr(I)10,Met(O)17]VIP and [Tyr(I)22,Met(O)17]VIP which, unlike [Met(O)17]VIP itself, had slightly lower potency than VIP

A novel multidimensional protein identification technology approach combining protein size exclusion prefractionation, peptide zwitterion-ion hydrophilic interaction chromatography, and nano-ultraperformance RP chromatography/nESI-MS2 for the in-depth analysis of the serum proteome and phosphoproteome: application to clinical sera derived from humans with benign prostate hyperplasia.

Science.gov (United States)

Garbis, Spiros D; Roumeliotis, Theodoros I; Tyritzis, Stavros I; Zorpas, Kostas M; Pavlakis, Kitty; Constantinides, Constantinos A

2011-02-01

The current proof-of-principle study was aimed toward development of a novel multidimensional protein identification technology (MudPIT) approach for the in-depth proteome analysis of human serum derived from patients with benign prostate hyperplasia (BPH) using rational chromatographic design principles. This study constituted an extension of our published work relating to the identification and relative quantification of potential clinical biomarkers in BPH and prostate cancer (PCa) tissue specimens. The proposed MudPIT approach encompassed the use of three distinct yet complementary liquid chromatographic chemistries. High-pressure size-exclusion chromatography (SEC) was used for the prefractionation of serum proteins followed by their dialysis exchange and solution phase trypsin proteolysis. The tryptic peptides were then subjected to offline zwitterion-ion hydrophilic interaction chromatography (ZIC-HILIC) fractionation followed by their online analysis with reversed-phase nano-ultraperformance chromatography (RP-nUPLC) hyphenated to nanoelectrospray ionization-tandem mass spectrometry using an ion trap mass analyzer. For the spectral processing, the sequential use of the SpectrumMill, Scaffold, and InsPecT software tools was applied for the tryptic peptide product ion MS(2) spectral processing, false discovery rate (FDR) assessment, validation, and protein identification. This milestone serum analysis study allowed the confident identification of over 1955 proteins (p ≤ 0.05; FDR ≤ 5%) with a broad spectrum of biological and physicochemical properties including secreted, tissue-specific proteins spanning approximately 12 orders of magnitude as they occur in their native abundance levels in the serum matrix. Also encompassed in this proteome was the confident identification of 375 phosphoproteins (p ≤ 0.05; FDR ≤ 5%) with potential importance to cancer biology. To demonstrate the performance characteristics of this novel MudPIT approach, a comparison

1H nmr spectra of dichloro and dihydroxy derivatives of methylcyclosiloxanes

International Nuclear Information System (INIS)

Lavrukhin, B.D.

1986-01-01

The authors report on a continuation of an investigation of how the nature of the substituents on the Si atoms influences the character of the spectra. As objects of investigation, the authors took the dichloro and dihydroxy derivatives of cyclosiloxanes with 4 to 8 Si atoms in the ring. Shown are tables of chemical shifts of protons of CH 3 groups in chloromethylcyclosiloxanes, and chemical shifts of protons of CH 3 groups in linear methylsiloxanes and chloromethylsiloxanes. Additivity was demonstrated for chemical shifts of CH 3 group protons in dichloromethylcyclosiloxanes, and the increments of chemical shift were obtained for 8-, 10-, 12-, 14-, and 16-membered rings. It was established that the chemical shifts in the spectra of the dihydroxy derivatives are nonadditive

Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2--The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates.

Science.gov (United States)

Luca, Oana R; Fenwick, Aidan Q

2015-11-01

The present review covers organic transformations involved in the reduction of CO2 to chemical fuels. In particular, we focus on reactions of CO2 with organic molecules to yield carboxylic acid derivatives as a first step in CO2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standing knowledge of CO2 reactivity from organic chemistry, organocatalysis, surface science and electrocatalysis. We point out some possible non-faradaic chemical reactions that may contribute to product distributions in the production of solar fuels from CO2. These reactions may be accelerated by thermal effects such as resistive heating and illumination. Copyright © 2015 Elsevier B.V. All rights reserved.

Lysine-Grafted MCM-41 Silica as an Antibacterial Biomaterial.

Science.gov (United States)

Villegas, María F; Garcia-Uriostegui, Lorena; Rodríguez, Ofelia; Izquierdo-Barba, Isabel; Salinas, Antonio J; Toriz, Guillermo; Vallet-Regí, María; Delgado, Ezequiel

2017-09-26

This paper proposes a facile strategy for the zwitterionization of bioceramics that is based on the direct incorporation of l-lysine amino acid via the ε-amino group onto mesoporous MCM-41 materials. Fourier transform infrared (FTIR) studies of lysine-grafted MCM-41 (MCM-LYS) simultaneously showed bands at 3080 and 1540 cm -1 and bands at 1625 and 1415 cm -1 corresponding to -NH 3+ /COO - pairs, which demonstrate the incorporation of the amino acid on the material surface keeping its zwitterionic character. Both elemental and thermogravimetric analyses showed that the amount of grafted lysine was 8 wt. % based on the bioceramic total weight. Moreover, MCM-LYS exhibited a reduction of adhesion of S. aureus and E. coli bacteria in 33% and 50%, respectively at physiological pH, as compared with pristine MCM-41. Biofilm studies onto surfaces showed that lysine functionalization elicited a reduction of the area covered by S. aureus biofilm from 42% to only 5% (88%). This research shows a simple and effective approach to chemically modify bioceramics using single amino acids that provides zwitterionic functionality, which is useful to develop new biomaterials that are able to resist bacterial adhesion.

Lysine-Grafted MCM-41 Silica as an Antibacterial Biomaterial

Directory of Open Access Journals (Sweden)

María F. Villegas

2017-09-01

Full Text Available This paper proposes a facile strategy for the zwitterionization of bioceramics that is based on the direct incorporation of l-lysine amino acid via the ε-amino group onto mesoporous MCM-41 materials. Fourier transform infrared (FTIR studies of lysine-grafted MCM-41 (MCM-LYS simultaneously showed bands at 3080 and 1540 cm−1 and bands at 1625 and 1415 cm−1 corresponding to -NH3+/COO− pairs, which demonstrate the incorporation of the amino acid on the material surface keeping its zwitterionic character. Both elemental and thermogravimetric analyses showed that the amount of grafted lysine was 8 wt. % based on the bioceramic total weight. Moreover, MCM-LYS exhibited a reduction of adhesion of S. aureus and E. coli bacteria in 33% and 50%, respectively at physiological pH, as compared with pristine MCM-41. Biofilm studies onto surfaces showed that lysine functionalization elicited a reduction of the area covered by S. aureus biofilm from 42% to only 5% (88%. This research shows a simple and effective approach to chemically modify bioceramics using single amino acids that provides zwitterionic functionality, which is useful to develop new biomaterials that are able to resist bacterial adhesion.

XPS/NEXAFS spectroscopic and conductance studies of glycine on AlGaN/GaN transistor devices

Science.gov (United States)

Myers, Matthew; Khir, Farah Liyana Muhammad; Home, Michael A.; Mennell, Christopher; Gillbanks, Jeremy; Tadich, Anton; Baker, Murray V.; Nener, Brett D.; Parish, Giacinta

2018-03-01

We report on a study using a combination of XPS/NEXAFS and conductivity measurements to develop a fundamental understanding of how dipolar molecules interact with the heterostructure device surface and affect the device conductivity of AlGaN/GaN heterostructure-based transistors. In such structures, which are increasingly being investigated for chemical and biological sensing, a 2-dimensional electron gas spontaneously forms at the layer interface that is sensitive to the charge characteristics of the exposed surface. Glycine, chosen for this study because it is the simplest of the amino acids and is known to form a zwitterionic configuration when stabilized through intermolecular interactions, was evaporated under ultra-high vacuum conditions onto the device surface and subsequently both XPS/NEXAFS and conductivity measurements were conducted. NEXAFS spectra show a preferential orientation for the Glycine molecules on the surface and evidence for both neutral and zwitterionic species on the surface. In situ conductivity measurements suggest that the negatively charged carboxylate group is closest to the surface. These results are a unique and pivotal contribution to the previous and at times conflicting literature on the zwitterionic nature of Glycine.

Local chemical potential, local hardness, and dual descriptors in temperature dependent chemical reactivity theory.

Science.gov (United States)

Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

2017-05-31

In this work we establish a new temperature dependent procedure within the grand canonical ensemble, to avoid the Dirac delta function exhibited by some of the second order chemical reactivity descriptors based on density functional theory, at a temperature of 0 K. Through the definition of a local chemical potential designed to integrate to the global temperature dependent electronic chemical potential, the local chemical hardness is expressed in terms of the derivative of this local chemical potential with respect to the average number of electrons. For the three-ground-states ensemble model, this local hardness contains a term that is equal to the one intuitively proposed by Meneses, Tiznado, Contreras and Fuentealba, which integrates to the global hardness given by the difference in the first ionization potential, I, and the electron affinity, A, at any temperature. However, in the present approach one finds an additional temperature-dependent term that introduces changes at the local level and integrates to zero. Additionally, a τ-hard dual descriptor and a τ-soft dual descriptor given in terms of the product of the global hardness and the global softness multiplied by the dual descriptor, respectively, are derived. Since all these reactivity indices are given by expressions composed of terms that correspond to products of the global properties multiplied by the electrophilic or nucleophilic Fukui functions, they may be useful for studying and comparing equivalent sites in different chemical environments.

Consequences of transition from liquid chromatography to supercritical fluid chromatography on the overall performance of a chiral zwitterionic ion-exchanger.

Science.gov (United States)

Wolrab, Denise; Frühauf, Peter; Gerner, Christopher; Kohout, Michal; Lindner, Wolfgang

2017-09-29

Major differences in the chromatographic performance of a zwitterion ion-exchange type (ZWIX) chiral stationary phase (CSP) in supercritical fluid chromatography (SFC) and high-performance liquid chromatography (HPLC) have been observed. To explain these differences, transition from HPLC to SFC conditions has been performed. The amount of a protic organic modifier in supercritical carbon dioxide (scCO 2 ) was stepwise increased and the effect of this change studied using acidic, basic and ampholytic analytes. At the same time, the effect of various basic additives to the mobile phase and transient acidic buffer species, formed by the reaction of scCO 2 with the organic modifier and additives, was assessed. Evidence is provided that a transient acid together with the intrinsic counter-ions present in the ZWIX selector structure drive the elution of analytes even when no buffer is employed. We show that the tested analytes can be enantioseparated under both SFC and HPLC conditions; the best conditions for the resolution of ampholytes are in the so-called enhanced-fluidity mobile phase region. As a consequence, subcritical fluid and enhanced-fluidity mobile phase regions seem to be chromatographic modes with a high potential for operating ZWIX CSPs. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication and Sintering Behavior of Er:SrF2 Transparent Ceramics using Chemically Derived Powder

Science.gov (United States)

Liu, Jun; Liu, Peng; Wang, Jun; Xu, Xiaodong; Li, Dongzhen; Zhang, Jian; Nie, Xinming

2018-01-01

In this paper, we report the fabrication of high-quality 5 at. % Er3+ ions doped SrF2 transparent ceramics, the potential candidate materials for a mid-infrared laser-gain medium by hot-pressing at 700 °C for 40 h using a chemically-derived powder. The phase structure, densification, and microstructure evolution of the Er:SrF2 ceramics were systematically investigated. In addition, the grain growth kinetic mechanism of Er:SrF2 was clarified. The results showed lattice diffusion to be the grain growth mechanism in the Er:SrF2 transparent ceramic of which highest in-line transmittance reached 92% at 2000 nm, i.e., very close to the theoretical transmittance value of SrF2 single crystal. Furthermore, the emission spectra showed that the strongest emission band was located at 2735 nm. This means that it is possible to achieve a laser output of approximately 2.7 μm in the 5 at. % Er3+ ions doped SrF2 transparent ceramics. PMID:29565322

Fabrication and Sintering Behavior of Er:SrF2 Transparent Ceramics using Chemically Derived Powder

Directory of Open Access Journals (Sweden)

Jun Liu

2018-03-01

Full Text Available In this paper, we report the fabrication of high-quality 5 at. % Er3+ ions doped SrF2 transparent ceramics, the potential candidate materials for a mid-infrared laser-gain medium by hot-pressing at 700 °C for 40 h using a chemically-derived powder. The phase structure, densification, and microstructure evolution of the Er:SrF2 ceramics were systematically investigated. In addition, the grain growth kinetic mechanism of Er:SrF2 was clarified. The results showed lattice diffusion to be the grain growth mechanism in the Er:SrF2 transparent ceramic of which highest in-line transmittance reached 92% at 2000 nm, i.e., very close to the theoretical transmittance value of SrF2 single crystal. Furthermore, the emission spectra showed that the strongest emission band was located at 2735 nm. This means that it is possible to achieve a laser output of approximately 2.7 μm in the 5 at. % Er3+ ions doped SrF2 transparent ceramics.

Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.

Science.gov (United States)

Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

2014-03-01

Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. Copyright © 2013 Elsevier Ltd. All rights reserved.

Isotopic chemical weathering behaviour of Pb derived from a high-Alpine Holocene lake-sediment record

Science.gov (United States)

Gutjahr, Marcus; Süfke, Finn; Gilli, Adrian; Anselmetti, Flavio; Glur, Lukas; Eisenhauer, Anton

2017-04-01

Several studies assessing the chemical weathering systematics of Pb isotopes provided evidence for the incongruent release of Pb from source rocks during early stages of chemical weathering, resulting in runoff compositions more radiogenic (higher) than the bulk source-rock composition [e.g. 1]. Deep NW Atlantic seawater Pb isotope records covering the last glacial-interglacial transition further support these findings. Clear excursions towards highly radiogenic Pb isotopic input in the deep NW Atlantic seen during the early Holocene, hence after the large-scale retreat of the Laurentide Ice Sheet in North America, are interpreted to be controlled by preferential release of radiogenic Pb from U- and Th-rich mineral phases during early stages of chemical weathering that are less resistant to chemical dissolution than other rock-forming mineral phases [2-4]. To date, however, no terrestrial Pb isotope record exists that could corroborate the evidence from deep marine sites for efficient late deglacial weathering and washout of radiogenic Pb. We present a high-resolution adsorbed Pb isotope record from a sediment core retrieved from Alpine Lake Grimsel (1908 m.a.s.l.) in Switzerland, consisting of 117 Pb compositions over the past 10 kyr. This high-Alpine study area is ideally located for incipient and prolonged chemical weathering studies. The method used to extract the adsorbed lake Pb isotope signal is identical to previous marine approaches targeting the authigenic Fe-Mn oxyhydroxides fraction within the lake sediments [5, 6]. The Pb isotope compositions are further accompanied by various elemental ratios derived from the same samples that equally trace climatic boundary conditions in the Grimsel Lake area. The Pb isotopic composition recorded in Lake Grimsel is remarkably constant throughout the majority of the Holocene until ˜2.5 ka BP, despite variable sediment composition and -age, and isotopically relatively close to the signature of the granitic source rock

Inflation Rates, Car Devaluation, and Chemical Kinetics.

Science.gov (United States)

Pogliani, Lionello; Berberan-Santos, Mario N.

1996-01-01

Describes the inflation rate problem and offers an interesting analogy with chemical kinetics. Presents and solves the car devaluation problem as a normal chemical kinetic problem where the order of the rate law and the value of the rate constant are derived. (JRH)

Chemical Characterization of Beer Aging Products Derived from Hard Resin Components in Hops (Humulus lupulus L.).

Science.gov (United States)

Taniguchi, Yoshimasa; Yamada, Makiko; Taniguchi, Harumi; Matsukura, Yasuko; Shindo, Kazutoshi

2015-11-25

The bitter taste of beer originates from resins in hops (Humulus lupulus L.), which are classified into two subtypes (soft and hard). Whereas the nature and reactivity of soft-resin-derived compounds, such as α-, β-, and iso-α-acids, are well studied, there is only a little information on the compounds in hard resin. For this work, hard resin was prepared from stored hops and investigated for its compositional changes in an experimental model of beer aging. The hard resin contained a series of α-acid oxides. Among them, 4'-hydroxyallohumulinones were unstable under beer storage conditions, and their transformation induced primary compositional changes of the hard resin during beer aging. The chemical structures of the products, including novel polycyclic compounds scorpiohumulinols A and B and dicyclohumulinols A and B, were determined by HRMS and NMR analyses. These compounds were proposed to be produced via proton-catalyzed cyclization reactions of 4'-hydroxyallohumulinones. Furthermore, they were more stable than their precursor 4'-hydroxyallohumulinones during prolonged storage periods.

Chemical compositional, biological, and safety studies of a novel maple syrup derived extract for nutraceutical applications.

Science.gov (United States)

Zhang, Yan; Yuan, Tao; Li, Liya; Nahar, Pragati; Slitt, Angela; Seeram, Navindra P

2014-07-16

Maple syrup has nutraceutical potential given the macronutrients (carbohydrates, primarily sucrose), micronutrients (minerals and vitamins), and phytochemicals (primarily phenolics) found in this natural sweetener. We conducted compositional (ash, fiber, carbohydrates, minerals, amino acids, organic acids, vitamins, phytochemicals), in vitro biological, and in vivo safety (animal toxicity) studies on maple syrup extracts (MSX-1 and MSX-2) derived from two declassified maple syrup samples. Along with macronutrient and micronutrient quantification, thirty-three phytochemicals were identified (by HPLC-DAD), and nine phytochemicals, including two new compounds, were isolated and identified (by NMR) from MSX. At doses of up to 1000 mg/kg/day, MSX was well tolerated with no signs of overt toxicity in rats. MSX showed antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) assay) and anti-inflammatory (in RAW 264.7 macrophages) effects and inhibited glucose consumption (by HepG2 cells) in vitro. Thus, MSX should be further investigated for potential nutraceutical applications given its similarity in chemical composition to pure maple syrup.

Chemical Compositional, Biological, and Safety Studies of a Novel Maple Syrup Derived Extract for Nutraceutical Applications

Science.gov (United States)

2015-01-01

Maple syrup has nutraceutical potential given the macronutrients (carbohydrates, primarily sucrose), micronutrients (minerals and vitamins), and phytochemicals (primarily phenolics) found in this natural sweetener. We conducted compositional (ash, fiber, carbohydrates, minerals, amino acids, organic acids, vitamins, phytochemicals), in vitro biological, and in vivo safety (animal toxicity) studies on maple syrup extracts (MSX-1 and MSX-2) derived from two declassified maple syrup samples. Along with macronutrient and micronutrient quantification, thirty-three phytochemicals were identified (by HPLC-DAD), and nine phytochemicals, including two new compounds, were isolated and identified (by NMR) from MSX. At doses of up to 1000 mg/kg/day, MSX was well tolerated with no signs of overt toxicity in rats. MSX showed antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) assay) and anti-inflammatory (in RAW 264.7 macrophages) effects and inhibited glucose consumption (by HepG2 cells) in vitro. Thus, MSX should be further investigated for potential nutraceutical applications given its similarity in chemical composition to pure maple syrup. PMID:24983789

Empiricism or self-consistent theory in chemical kinetics?

International Nuclear Information System (INIS)

Gutman, E.M.

2007-01-01

To give theoretical background for mechanochemical kinetics, we need first of all to find a possibility to predict the kinetic parameters for real chemical processes by determining rate constants and reaction orders without developing strictly specialized and, to a great extent, artificial models, i.e. to derive the kinetic law of mass action from 'first principles'. However, the kinetic law of mass action has had only an empirical basis from the first experiments of Gulberg and Waage until now, in contrast to the classical law of mass action for chemical equilibrium rigorously derived in chemical thermodynamics from equilibrium condition. Nevertheless, in this paper, an attempt to derive the kinetic law of mass action from 'first principles' is made in macroscopic formulation. It has turned out to be possible owing to the methods of thermodynamics of irreversible processes that were unknown in Gulberg and Waage's time

Haenamindole, an unusual diketopiperazine derivative from a marine-derived Penicillium sp. KCB12F005.

Science.gov (United States)

Kim, Jong Won; Ko, Sung-Kyun; Son, Sangkeun; Shin, Kee-Sun; Ryoo, In-Ja; Hong, Young-Soo; Oh, Hyuncheol; Hwang, Bang Yeon; Hirota, Hiroshi; Takahashi, Shunji; Kim, Bo Yeon; Osada, Hiroyuki; Jang, Jae-Hyuk; Ahn, Jong Seog

2015-11-15

During the chemical investigation of marine-derived fungus, an unusual diketopiperazine (DKP) alkaloid, haenamindole (1), was isolated from a culture of the marine-derived fungus Penicillium sp. KCB12F005. The structure of 1, which possesses benzyl-hydroxypiperazindione and phenyl-pyrimidoindole rings system in the molecule, was elucidated by analysis of NMR and MS data. The stereochemistry of 1 was determined by ROESY and advanced Marfey's method. Copyright © 2015 Elsevier Ltd. All rights reserved.

The chemical juggernaut.

Science.gov (United States)

Cadbury, D

1997-01-01

Man-made chemicals pervade and support every aspect of modern living. The chemical industry has become such a powerful force in the global economy, sales of synthetic chemicals and products derived from them constitute well in excess of a third of the world's gross national product. But, these man-made chemicals are also 'elixirs of death,' the symbol of human destruction. Laboratory tests have shown that a number of chemicals in common use possess a remarkable property: they can weakly mimic or modify the action of human hormones. It has been proven that some chemicals found in plastics, pesticides, and industrial products are weakly estrogenic, modifying the action of the female hormone. In addition, other chemicals affect the male hormones, androgens, or anti-androgens; others are thought to target different hormone systems, such as thyroid and adrenal glands. Many research studies are being conducted to establish the impact of chemicals on human health. Of special concern are the rising incidence of testicular cancer, decline in human sperm counts, and the sharp rise of breast cancer. In conclusion, although there is a worldwide debate on the effects of chemical exposure on humans, the significance of findings for human health, concerning testicular and breast cancer, are still unknown. An international treaty is called for to control the use of the persistent hormonally active chemicals.

Zwitterionic Silane Copolymer for Ultra-Stable and Bright Biomolecular Probes Based on Fluorescent Quantum Dot Nanoclusters.

Science.gov (United States)

Dembele, Fatimata; Tasso, Mariana; Trapiella-Alfonso, Laura; Xu, Xiangzhen; Hanafi, Mohamed; Lequeux, Nicolas; Pons, Thomas

2017-05-31

Fluorescent semiconductor quantum dots (QDs) exhibit several unique properties that make them suitable candidates for biomolecular sensing, including high brightness, photostability, broad excitation, and narrow emission spectra. Assembling these QDs into robust and functionalizable nanosized clusters (QD-NSCs) can provide fluorescent probes that are several orders of magnitude brighter than individual QDs, thus allowing an even greater sensitivity of detection with simplified instrumentation. However, the formation of compact, antifouling, functionalizable, and stable QD-NSCs remains a challenging task, especially for a use at ultralow concentrations for single-molecule detection. Here, we describe the development of fluorescent QD-NSCs envisioned as a tool for fast and sensitive biomolecular recognition. First, QDs were assembled into very compact 100-150 nm diameter spherical aggregates; the final QD-NSCs were obtained by growing a cross-linked silica shell around these aggregates. Hydrolytic stability in several concentration and pH conditions is a key requirement for a potential and efficient single-molecule detection tool. However, the hydrolysis of Si-O-Si bonds leads to desorption of monosilane-based surface groups at very low silica concentrations or in a slightly basic medium. Thus, we designed a novel multidentate copolymer composed of multiple silane as well as zwitterionic monomers. Coating silica beads with this multidentate copolymer provided a robust surface chemistry that was demonstrated to be stable against hydrolysis, even at low concentrations. Copolymer-coated silica beads also showed low fouling properties and high colloidal stability in saline solutions. Furthermore, incorporation of additional azido-monomers enabled easy functionalization of QD-NSCs using copper-free bio-orthogonal cyclooctyne-azide click chemistry, as demonstrated by a biotin-streptavidin affinity test.

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.

Rapid and reliable protein structure determination via chemical shift threading.

Science.gov (United States)

Hafsa, Noor E; Berjanskii, Mark V; Arndt, David; Wishart, David S

2018-01-01

Protein structure determination using nuclear magnetic resonance (NMR) spectroscopy can be both time-consuming and labor intensive. Here we demonstrate how chemical shift threading can permit rapid, robust, and accurate protein structure determination using only chemical shift data. Threading is a relatively old bioinformatics technique that uses a combination of sequence information and predicted (or experimentally acquired) low-resolution structural data to generate high-resolution 3D protein structures. The key motivations behind using NMR chemical shifts for protein threading lie in the fact that they are easy to measure, they are available prior to 3D structure determination, and they contain vital structural information. The method we have developed uses not only sequence and chemical shift similarity but also chemical shift-derived secondary structure, shift-derived super-secondary structure, and shift-derived accessible surface area to generate a high quality protein structure regardless of the sequence similarity (or lack thereof) to a known structure already in the PDB. The method (called E-Thrifty) was found to be very fast (often chemical shift refinement, these results suggest that protein structure determination, using only NMR chemical shifts, is becoming increasingly practical and reliable. E-Thrifty is available as a web server at http://ethrifty.ca .

Synthesis and physical-chemical properties of 3-benzyl-8-propylxanthinyl-7-acetic acid and its derivatives

Directory of Open Access Journals (Sweden)

E. K. Mikhalchenko

2017-04-01

Full Text Available Introduction. Heterocyclic compounds play an important role in the metabolic processes of human organism. Structures of vitamins, nucleotides, chromoproteins are based on Nitrogen-containing heterocycles (purine, pyrimidine, thiazole etc. Thus, it was obvious to use these organic substances as basic molecules for synthetic research of biologically active compounds which could be used for treatment of different pathological processes. In their research, some scientist pay special attention to xanthine derivatives that are well-known low toxic natural compounds with wide spectrum of pronounced pharmacological properties (antioxidant, diuretic, antibacterial, anti-inflammatory etc. Insertion of carboxyl group in the structure of xanthine molecule is a prospective ability of its synthetic potential increasing. Aim of our research was the development of method of 3-benzyl-8-propylxanthinyl-7-acetic acid and its derivatives synthesis and studying their physical-chemical properties. Materials and methods. Melting points were determined using capillary method on DMP (M. 1Н NMR-spectra were recorded by Varian Mercury VX-200 device (company «Varian», USA solvent – (DMSO-d6, internal standard – ТМS. Elemental analysis of obtained compounds was produced on device Elementar Vario L cube. Results and discussion. We selected 3-benzyl-8-propyl xanthine as initial compound for our study. By its interaction with chloroacetic acid, chloroacetamide or propyl chloroacetate in DMF in the presence of calculated amount of NaHCO3 we synthesized 3-benzyl-8-propylxanthinyl-7-acetic acid its ester and amide. At the same time we found that obtaining of xanthinyl-7-acetic acid by hydrolysis of its ester produced with higher yield. On the next stage of our research we synthesized a number of water-soluble salts of 3-benzyl-8-propylxanthinyl-7-acetic acid by reaction of acid with different primary and secondary amines. The structures of all obtained compounds were

Proteomic Analysis of Human Adipose Derived Stem Cells during Small Molecule Chemical Stimulated Pre-neuronal Differentiation.

Science.gov (United States)

Santos, Jerran; Milthorpe, Bruce K; Herbert, Benjamin R; Padula, Matthew P

2017-11-30

Adipose derived stem cells (ADSCs) are acquired from abdominal liposuction yielding a thousand fold more stem cells per millilitre than those from bone marrow. A large research void exists as to whether ADSCs are capable of transdermal differentiation toward neuronal phenotypes. Previous studies have investigated the use of chemical cocktails with varying inconclusive results. Human ADSCs were treated with a chemical stimulant, beta-mercaptoethanol, to direct them toward a neuronal-like lineage within 24 hours. Quantitative proteomics using iTRAQ was then performed to ascertain protein abundance differences between ADSCs, beta-mercaptoethanol treated ADSCs and a glioblastoma cell line. The soluble proteome of ADSCs differentiated for 12 hours and 24 hours was significantly different from basal ADSCs and control cells, expressing a number of remodeling, neuroprotective and neuroproliferative proteins. However toward the later time point presented stress and shock related proteins were observed to be up regulated with a large down regulation of structural proteins. Cytokine profiles support a large cellular remodeling shift as well indicating cellular distress. The earlier time point indicates an initiation of differentiation. At the latter time point there is a vast loss of cell population during treatment. At 24 hours drastically decreased cytokine profiles and overexpression of stress proteins reveal that exposure to beta-mercaptoethanol beyond 24 hours may not be suitable for clinical application as our results indicate that the cells are in trauma whilst producing neuronal-like morphologies. The shorter treatment time is promising, indicating a reducing agent has fast acting potential to initiate neuronal differentiation of ADSCs.

Biotechnology for renewable chemicals

DEFF Research Database (Denmark)

Borodina, Irina; Kildegaard, Kanchana Rueksomtawin; Jensen, Niels Bjerg

2014-01-01

The majority of the industrial organic chemicals are derived from fossil sources. With the oil and gas resources becoming limiting, biotechnology offers a sustainable alternative for production ofchemicals from renewable feedstocks. Yeast is an attractive cell factory forsustainable production...

Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

Energy Technology Data Exchange (ETDEWEB)

Li Kun [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States); Xing Baoshan [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States) and Northeast Institute of Geography and Agro-ecology, CAS, Harbin 150040 (China)]. E-mail: bx@pssci.umass.edu; Torello, William A. [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States)

2005-03-01

Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils. - Dissolved organic matter could result in enhanced transport of chemicals applied to turf.

Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

International Nuclear Information System (INIS)

Li Kun; Xing Baoshan; Torello, William A.

2005-01-01

Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils. - Dissolved organic matter could result in enhanced transport of chemicals applied to turf

Chemical ozone losses in Arctic and Antarctic polar winter/spring season derived from SCIAMACHY limb measurements 2002–2009

Directory of Open Access Journals (Sweden)

T. Sonkaew

2013-02-01

Full Text Available Stratospheric ozone profiles are retrieved for the period 2002–2009 from SCIAMACHY measurements of limb-scattered solar radiation in the Hartley and Chappuis absorption bands of ozone. This data set is used to determine the chemical ozone losses in both the Arctic and Antarctic polar vortices by averaging the ozone in the vortex at a given potential temperature. The chemical ozone losses at isentropic levels between 450 K and 600 K are derived from the difference between observed ozone abundances and the ozone modelled taking diabatic cooling into account, but no chemical ozone loss. Chemical ozone losses of up to 30–40% between mid-January and the end of March inside the Arctic polar vortex are reported. Strong inter-annual variability of the Arctic ozone loss is observed, with the cold winters 2004/2005 and 2006/2007 showing chemical ozone losses inside the polar vortex at 475 K, where 1.7 ppmv and 1.4 ppmv of ozone were removed, respectively, over the period from 22 January to beginning of April and 0.9 ppmv and 1.2 ppmv, respectively, during February. For the winters of 2007/2008 and 2002/2003, ozone losses of about 0.8 ppmv and 0.4 ppmv, respectively are estimated at the 475 K isentropic level for the period from 22 January to beginning of April. Essentially no ozone losses were diagnosed for the relatively warm winters of 2003/2004 and 2005/2006. The maximum ozone loss in the SCIAMACHY data set was found in 2007 at the 600 K level and amounted to about 2.1 ppmv for the period between 22 January and the end of April. Enhanced losses close to this altitude were found in all investigated Arctic springs, in contrast to Antarctic spring. The inter-annual variability of ozone losses and PSC occurrence rates observed during Arctic spring is consistent with the known QBO effects on the Arctic polar vortex, with exception of the unusual Arctic winter 2008/2009.

The maximum total ozone mass loss of about 25 million tons was found in the

High-throughput dietary exposure predictions for chemical migrants from food contact substances for use in chemical prioritization.

Science.gov (United States)

Biryol, Derya; Nicolas, Chantel I; Wambaugh, John; Phillips, Katherine; Isaacs, Kristin

2017-11-01

Under the ExpoCast program, United States Environmental Protection Agency (EPA) researchers have developed a high-throughput (HT) framework for estimating aggregate exposures to chemicals from multiple pathways to support rapid prioritization of chemicals. Here, we present methods to estimate HT exposures to chemicals migrating into food from food contact substances (FCS). These methods consisted of combining an empirical model of chemical migration with estimates of daily population food intakes derived from food diaries from the National Health and Nutrition Examination Survey (NHANES). A linear regression model for migration at equilibrium was developed by fitting available migration measurements as a function of temperature, food type (i.e., fatty, aqueous, acidic, alcoholic), initial chemical concentration in the FCS (C 0 ) and chemical properties. The most predictive variables in the resulting model were C 0 , molecular weight, log K ow , and food type (R 2 =0.71, pchemicals identified via publicly-available data sources as being present in polymer FCSs were predicted for 12 food groups (combinations of 3 storage temperatures and food type). The model was parameterized with screening-level estimates of C 0 based on the functional role of chemicals in FCS. By combining these concentrations with daily intakes for food groups derived from NHANES, population ingestion exposures of chemical in mg/kg-bodyweight/day (mg/kg-BW/day) were estimated. Calibrated aggregate exposures were estimated for 1931 chemicals by fitting HT FCS and consumer product exposures to exposures inferred from NHANES biomonitoring (R 2 =0.61, pchemicals), they can provide critical refinement to aggregate exposure predictions used in risk-based chemical priority-setting. Published by Elsevier Ltd.

Chemical Composition and Cytotoxicity Evaluation of Essential Oil from Leaves of Casearia Sylvestris, Its Main Compound α-Zingiberene and Derivatives

Directory of Open Access Journals (Sweden)

Patricia Sartorelli

2013-08-01

Full Text Available Casearia sylvestris (Salicaceae, popularly known as “guaçatonga”, is a plant widely used in folk medicine to treat various diseases, including cancer. The present work deals with the chemical composition as well as the cytotoxic evaluation of its essential oil, its main constituent and derivatives. Thus, the crude essential oil from leaves of C. sylvestris was obtained using a Clevenger type apparatus and analyzed by GC/MS. This analysis afforded the identification of 23 substances, 13 of which corresponded to 98.73% of the total oil composition, with sesquiterpene a-zingiberene accounting for 50% of the oil. The essential oil was evaluated for cytotoxic activity against several tumor cell lines, giving IC50 values ranging from 12 to 153 mg/mL. Pure a-zingiberene, isolated from essential oil, was also evaluated against the tumor cell lines showing activity for HeLa, U-87, Siha and HL60 cell lines, but with IC50 values higher than those determined for the crude essential oil. Aiming to evaluate the effect of the double bonds of a-zingiberene on the cytotoxic activity, partially hydrogenated a-zingiberene (PHZ and fully hydrogenated a-zingiberene (THZ derivatives were obtained. For the partially hydrogenated derivative only cytotoxic activity to the B16F10-Nex2 cell line (IC50 65mg/mL was detected, while totally hydrogenated derivative showed cytotoxic activity for almost all cell lines, with B16F10-Nex2 and MCF-7 as exceptions and with IC50 values ranging from 34 to 65 mg/mL. These results indicate that cytotoxic activity is related with the state of oxidation of compound.

Chemical composition and cytotoxicity evaluation of essential oil from leaves of Casearia sylvestris, its main compound α-zingiberene and derivatives.

Science.gov (United States)

Bou, Diego Dinis; Lago, João Henrique G; Figueiredo, Carlos R; Matsuo, Alisson L; Guadagnin, Rafael C; Soares, Marisi G; Sartorelli, Patricia

2013-08-08

Casearia sylvestris (Salicaceae), popularly known as "guaçatonga", is a plant widely used in folk medicine to treat various diseases, including cancer. The present work deals with the chemical composition as well as the cytotoxic evaluation of its essential oil, its main constituent and derivatives. Thus, the crude essential oil from leaves of C. sylvestris was obtained using a Clevenger type apparatus and analyzed by GC/MS. This analysis afforded the identification of 23 substances, 13 of which corresponded to 98.73% of the total oil composition, with sesquiterpene a-zingiberene accounting for 50% of the oil. The essential oil was evaluated for cytotoxic activity against several tumor cell lines, giving IC50 values ranging from 12 to 153 mg/mL. Pure a-zingiberene, isolated from essential oil, was also evaluated against the tumor cell lines showing activity for HeLa, U-87, Siha and HL60 cell lines, but with IC50 values higher than those determined for the crude essential oil. Aiming to evaluate the effect of the double bonds of a-zingiberene on the cytotoxic activity, partially hydrogenated a-zingiberene (PHZ) and fully hydrogenated a-zingiberene (THZ) derivatives were obtained. For the partially hydrogenated derivative only cytotoxic activity to the B16F10-Nex2 cell line (IC50 65 mg/mL) was detected, while totally hydrogenated derivative showed cytotoxic activity for almost all cell lines, with B16F10-Nex2 and MCF-7 as exceptions and with IC50 values ranging from 34 to 65 mg/mL. These results indicate that cytotoxic activity is related with the state of oxidation of compound.

Metal complex derivatives of hydrogen uranyl phosphate

International Nuclear Information System (INIS)

Grohol, D.; Blinn, E.L.

1994-01-01

Derivatives of hydrogen uranyl phosphate were prepared by incorporating transition metal complexes into the uranyl phosphate matrix. The transition metal complexes employed include bis(ethylenediamine)copper(II), bis(1,3-propanediamine)copper(II) chloride, (triethylenetetramine)copper(II), (1,4,8,11-tetraazacyclotetradecane)copper(II), (1,4,8,12-tetraazacyclopentadecane)copper(II), (1,4,8,11-tetraazacyclotetradecane)nickel(II) chloride, (triethylenetetramine)nickel(II) and others. The chemical analyses of these derivatives indicated that the incorporation of the transition metal complexes into the uranyl phosphate matrix via ion exchange was not stoichiometric. The extent of ion exchange is dependent on the size and structure of the transition metal complex. All complexes were characterized by X-ray powder diffractometry, electronic and infrared spectra, thermal analyses and chemical analysis. An attempt was made to correlate the degree of quenching of the luminescence of the uranyl ion to the spacing between the uranyl phosphate layers in the derivatives

Synthesis of acetylenic derivatives of hydroxynaphthoquinone

International Nuclear Information System (INIS)

Sanchez Kopper, Andres

2010-01-01

The acetylene derivatives synthesis 2-hydroxy-1 ,4-naphthoquinones was studied using different reaction conditions: coupling with copper and silver acetylides, Sonogashira reaction with and without CU (I) as cocatalyst. The reaction conditions are optimized for coupling of iodine lawson and ylide phenyl lawsone of iodine with various terminal acetylenes: phenyl acetylene, propargyl alcohol, 1-heptin and 2-methyl-3-butyne-2-ol. Also, reactants such as bromides of hidroxinaphthoquinones were used with protecting groups such as acetate, methoxy, phenyloxy, benzyloxy and tricloroetoxy. The synthesis of 2-hydroxy-3-(3-hydroxy-3-ynyl-1-methylbutane)-1,4-naphthoquinone, 2-methoxy-3-(2-phenylethynyl) -1,4-naphthoquinone and 2-(2-phenylethynyl)-3-(2,2,2-tricloroetoxy)-1,4-naphthoquinone was performed with rates of return of 22%, 57% and 67% respectively. The reaction of the yodolawsona was obtained with 3-chloro-3-methyl-1-butyne in the presence of CuI, CsI and Cs 2 Co 3 obtaining the enol ether: 3,3-dimethyl-2-methyl-2 ,3-dihydronaphto [2 ,3-b]furan-4,9-dione (dehydro-α-dunion), with a rate of return of 58%. This enol ether was used as a reactant for the formation, through a regioselective hydrogenation with PtO 2 /t-butanol of α-dunion with a yield of 50%. Furthermore, by acid hydrolysis with H 2 SO 4 has been possible to obtain a percentage yield of 75% streptocarpone. Both, α-dunion and streptocarpone, natural products extracted from Streptocarpus dunni shrub, with antiparasitic activity, and which so far had not presented an efficient synthesis. A mechanism is proposed for the reaction of formation of the enol ether where it is presumed the presence of a zwitterion-vinyl carbene as key intermediate of the reaction. All products were characterized by spectroscopy 1 H and 13 C-NMR, UV-Vis and IR. (author) [es

The Nemertine Toxin Anabaseine and Its Derivative DMXBA (GTS-21: Chemical and Pharmacological Properties

Directory of Open Access Journals (Sweden)

Hugo R. Arias

2006-04-01

Full Text Available Abstract: Nemertines are a phylum of carnivorous marine worms that possess a variety of alkaloidal, peptidic or proteinaceous toxins that serve as chemical defenses against potential predators. The hoplonemertines additionally envenomate their prey with a mixture of proboscis alkaloids delivered with the help of a calcareous stylet that punctures the skin of the victim. Anabaseine, the first of these alkaloids to be identified, stimulates a wide variety of animal nicotinic acetylcholine receptors (AChRs, especially the neuromuscular [e.g., α12β1γδ (embryogenic or α12β1γε (adult] and α7 AChRs that are inhibited by the snake peptide α-bungarotoxin. A synthetic derivative, 3-(2,4-Dimethoxybenzylidene-Anabaseine (DMXBA; also called GTS-21, improves memory in experimental animals and humans and is currently in clinical trials to determine whether it can ameliorate cognitive problems associated with schizophrenia. Here we summarize present knowledge concerning the chemistry and mechanisms of action of these two substances (anabaseine and DMXBA on AChRs, especially those found in the mammalian brain.

Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles.

Science.gov (United States)

Addison, Timothy; Cayre, Olivier J; Biggs, Simon; Armes, Steven P; York, David

2010-05-04

Using a layer-by-layer (LbL) approach, this work presents the preparation of hollow microcapsules with a membrane constructed entirely from a cationic/zwitterionic pair of pH-responsive block copolymer micelles. Our previous work with such systems highlighted that, in order to retain the responsive nature of the individual micelles contained within the multilayer membranes, it is important to optimize the conditions required for the selective dissolution of the sacrificial particulate templates. Consequently, here, calcium carbonate particles have been employed as colloidal templates as they can be easily dissolved in aqueous environments with the addition of chelating agents such as ethylenediaminetetraacetic acid (EDTA). Furthermore, the dissolution can be carried out in solutions buffered to a desirable pH so not to adversely affect the pH sensitive micelles forming the capsule membranes. First, we have deposited alternating layers of anionic poly[2-(dimethylamino)ethyl methacrylate-block-poly(2-(diethylamino)ethyl methacrylate)] (PDMA-PDEA) and cationic poly(2-(diethylamino)ethyl)methacrylate-block-poly(methacrylic acid) (PDEA-PMAA) copolymer micelles onto calcium carbonate colloidal templates. After deposition of five micelle bilayers, addition of dilute EDTA solution resulted in dissolution of the calcium carbonate and formation of hollow polymer capsules. The capsules were imaged using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which shows that the micelle/micelle membrane is sufficiently robust to withstand dissolution of the supporting template. Quartz crystal microbalance studies were conducted and provide good evidence that the micelle multilayer structure is retained after EDTA treatment. In addition, a hydrophobic dye was incorporated into the micelle cores prior to adsorption. After dissolution of the particle template, the resulting hollow capsules retained a high concentration of dye, suggesting that the core

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. MURALIDARAN KALIYAPERUMALA. Articles written in Journal of Chemical Sciences. Volume 129 Issue 8 August 2017 pp 1233-1245 REGULAR ARTICLE. A novel synthesis of chromone based unnatural α-amino acid derivatives · VENU KANDULA RAMAKRISHNA ...

Chemical modification, antioxidant and α-amylase inhibitory activities of corn silk polysaccharides.

Science.gov (United States)

Chen, Shuhan; Chen, Haixia; Tian, Jingge; Wang, Yanwei; Xing, Lisha; Wang, Jia

2013-10-15

Water-soluble corn silk polysaccharides (CSPS) were chemically modified to obtain their sulfated, acetylated and carboxymethylated derivatives. Chemical characterization and bioactivities of CSPS and its derivatives were comparatively investigated by chemical methods, gas chromatography, gel filtration chromatography, scanning electron microscope, infrared spectroscopy and circular dichroism spectroscopy, scavenging DPPH free radical assay, scavenging hydroxyl radical assay, ferric reducing power assay, lipid peroxidation inhibition assay and α-amylase activity inhibitory assay, respectively. Among the three derivatives, carboxylmethylated polysaccharide (C-CSPS) demonstrated higher solubility, narrower molecular weight distribution, lower intrinsic viscosity, a hyperbranched conformation, significantly higher antioxidant and α-amylase inhibitory abilities compared with the native polysaccharide and other derivatives. C-CSPS might be used as a novel nutraceutical agent for human consumption. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mobility of plume-derived volcanogenic elements in meteoric water at Nyiragongo volcano (Congo) inferred from the chemical composition of single rainfall events

Science.gov (United States)

Liotta, Marcello; Shamavu, Patient; Scaglione, Sarah; D'Alessandro, Walter; Bobrowski, Nicole; Bruno Giuffrida, Giovanni; Tedesco, Dario; Calabrese, Sergio

2017-11-01

The chemical composition of single rainfall events was investigated at Nyiragongo volcano (Democratic Republic of Congo) with the aim of determining the relative contributions of plume-derived elements. The different locations of the sampling sites allowed both plume-affected samples (hereafter referred to as ;fumigated samples;) and samples representative of the local background to be collected. The chemical composition of the local background reflects the peculiar geographic features of the area, being influenced by biomass burning, geogenic dust, and biological activity. Conversely, fumigated samples contain large amounts of volcanogenic elements that can be clearly distinguished from the local background. These elements are released into the atmosphere from the persistently boiling lava lake of the Nyiragongo crater and from the neonate lava lake of Nyamulagira. These emissions result in a volcanic plume that includes solid particles, acidic droplets, and gaseous species. The chemical signature of the volcanic emissions appears in falling raindrops as they interact with the plume. HCl and HBr readily dissolve in water, and so their ratio in rain samples reflects that of the volcanic plume. The transport of HF is mediated by the large amount of silicate particles generated at the magma-air interface. SO2 is partially converted into SO42- that dissolves in water. The refractory elements dissolved in rain samples derive from the dissolution of silicate particles, and most of them (Al, Mg, Ca, and Sr) are present at exactly the same molar ratios as in the rocks. In contrast, elements such as Na, K, Rb, Cu, and Pb are enriched relative to the whole-rock composition, suggesting that they are volatilized during magma degassing. After correcting for the dissolution of silicate particles, we can define that the volatility of the elements decreases in the following order: Pb ≫ Rb > K > Na. This finding, which is the first for a volcanic plume, is consistent with

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. MARZIEH ABBASI. Articles written in Journal of Chemical Sciences. Volume 129 Issue 8 August 2017 pp 1257-1266 REGULAR ARTICLE. Synthesis, characterization and in vitro antibacterial activity of novel phthalazine sulfonamide derivatives · MARZIEH ABBASI SEYED ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. MARAVANJI S BALAKRISHNA. Articles written in Journal of Chemical Sciences. Volume 129 Issue 4 April 2017 pp 471-481 Regular Article. Hydrazone derivatives appended to diphenylphosphine oxide as anion sensors · MARUTHAI KUMARAVEL JOEL T MAGUE ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. BIPUL KUMAR. Articles written in Journal of Chemical Sciences. Volume 129 Issue 2 February 2017 pp 211-222 Regular Article. Synthesis and antibacterial activity screening of quaternary ammonium derivatives of triazolyl pyranochromenones · PREETI YADAV BIPUL ...

Zwitterion-functionalized polymer microspheres as a sorbent for solid phase extraction of trace levels of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) prior to their determination by ICP-MS.

Science.gov (United States)

Jia, Xiaoyu; Gong, Dirong; Zhao, Junyi; Ren, Hongyun; Wang, Jiani; Zhang, Xian

2018-03-19

This paper describes the preparation of zwitterion-functionalized polymer microspheres (ZPMs) and their application to simultaneous enrichment of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) from environmental water samples. The ZPMs were prepared by emulsion copolymerization of ethyl methacrylate, 2-diethylaminoethyl methacrylate and triethylene glycol dimethyl acrylate followed by modification with 1,3-propanesultone. The components were analyzed by elemental analyses as well as Fourier transform infrared spectroscopy, and the structures were characterized by scanning electron microscopy and transmission electron microscopy. The ZPMs were packed into a mini-column for on-line solid-phase extraction (SPE) of the above metal ions. Following extraction with 40 mM NH 4 NO 3 and 0.5 M HNO 3 solution, the ions were quantified by ICP-MS. Under the optimized conditions, the enrichment factors (from a 40 mL sample) are up to 60 for the ions V(V), As(III), Sb(III) and Hg(II), and 55 for Cr(III) and Sn(IV). The detection limits are 1.2, 3.4, 1.0, 3.7, 2.1 and 1.6 ng L -1 for V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II), respectively, and the relative standard deviations (RSDs) are below 5.2%. The feasibility and accuracy of the method were validated by successfully analyzing six certified reference materials as well as lake, well and river waters. Graphical abstract Zwitterion-functionalized polymer microspheres (ZPMs) were prepared and packed into a mini-column for on-line solid-phase extraction (SPE) via pump 1. Then V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) ions in environmental waters were eluted and submitted to ICP-MS via pump 2.

Synthesis, characterization and computational studies of 3-{(E)-[(2-hydroxyphenyl)imino]methyl}benzene-1,2-diol and molecular structure of its zwitterionic form

Science.gov (United States)

Ezeorah, Julius Chigozie; Ossai, Valentine; Obasi, Lawrence Nnamdi; Elzagheid, Mohamed I.; Rhyman, Lydia; Lutter, Michael; Jurkschat, Klaus; Dege, Necmi; Ramasami, Ponnadurai

2018-01-01

The Schiff base 3-{(E)-[(2-hydroxyphenyl)imino]methyl}benzene-1,2-diol was synthesized by the condensation of 2,3-dihydroxybenzaldehyde and 2-aminophenol in water at room temperature. The crystal was grown using two solvents (dry methanol and 60% methanol). The compound was characterized using elemental microanalysis, IR, NMR, UV spectroscopies and single-crystal X-ray diffraction crystallography. The X-ray structure reveals that the Schiff base crystallizes as a methanol solvate in dry methanol with triclinic crystal system, space group P-1 and Z = 2 in the unit cell and as a non-methanol solvate in 60% methanol with triclinic crystal system, space group P-1 and Z = 4 in the unit cell. The compound showed absorption bands at 272, 389, 473 and 602 nm in DMSO. These bands were assigned as π → π ∗, n → π∗ and n-σ∗ transitions. The 473 and 602 nm bands in DMSO reveal that the compound exists in tautomeric forms. The presence of N-H, C-O and Cdbnd N stretching vibrations in the IR spectrum indicates that the compound is zwitterionic in the solid state. This study was supplemented using density functional theory method.

The Theory of Thermodynamics for Chemical Reactions in Dispersed Heterogeneous Systems

Science.gov (United States)

Yongqiang; Baojiao; Jianfeng

1997-07-01

In this paper, the expressions of Gibbs energy change, enthalpy change, entropy change, and equilibrium constant for chemical reactions in dispersed heterogeneous systems are derived using classical thermodynamics theory. The thermodynamical relations for the same reaction system between the dispersed and the block state are also derived. The effects of degree of dispersion on thermodynamical properties, reaction directions, and chemical equilibria are discussed. The results show that the present equation of thermodynamics for chemical reactions is only a special case of the above-mentioned formulas and that the effect of the dispersity of a heterogeneous system on the chemical reaction obeys the Le Chatelier principle of movement of equilibria.

Synthesis and characterization of N-hydroxysuccinimide ester chemical affinity derivatives of asialoorosomucoid that covalently cross-link to galactosyl receptors on isolated rat hepatocytes

International Nuclear Information System (INIS)

Herzig, M.C.S.; Weigel, P.H.

1989-01-01

The authors have developed chemical affinity reagents for the hepatic galactosyl receptor. Asialoorosomucoid (ASOR) was derivatized with five homobifunctional N-hydroxysuccinimide (NHS) ester cross-linkers. NHS/ASOR derivatives were synthesized, purified, and applied within 10 min to isolated rat hepatocytes at 4 degree C. Specific binding of these 125 I-labeled derivatives was ∼90% in the presence of either EGTA or excess ASOR. Specific cross-linking assessed by the resistance of specifically bound NHS/ 125 I-ASOR to release by EGTA, was 50-75% of the specifically bound ligand. The extent of specific cross-linking correlated with the average number of NHS groups per ASOR and was controlled by varying the molar ratio of cross-linker to ASOR during the synthesis. After being cross-linked with any of the NHS/ 125 I-ASOR derivatives, cells were washed with EGTA, solubilized in Triton X-100, and analyzed by SDA-PAGE and autoradiography. They conclude that all three receptor subunits can cross-link to ligand. They propose a model in which the native receptor is a heterohexamer composed of four subunits of RHL 1 and two subunits of RHL 2 and/or RHL 3

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. LAYLA TAIB. Articles written in Journal of Chemical Sciences. Volume 128 Issue 5 May 2016 pp 745-752 Regular Articles. Thermolysis of some N-arylbenzamidoximes: Mechanistic studies for formation of anilide, oxazole and imidazole derivatives · ABDEL-AAL GABER ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. T SHANMUGANATHAN. Articles written in Journal of Chemical Sciences. Volume 129 Issue 1 January 2017 pp 117-130 Regular Article. Synthesis, in vitro anti-inflammatory activity and molecular docking studies of novel 4,5-diarylthiophene-2-carboxamide derivatives.

Electrochemical and quantum chemical studies of some indole derivatives as corrosion inhibitors for C38 steel in molar hydrochloric acid

International Nuclear Information System (INIS)

Lebrini, M.; Robert, F.; Vezin, H.; Roos, C.

2010-01-01

A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 o C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The ΔG ads o values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).

N-acylated peptides derived from human lactoferricin perturb organization of cardiolipin and phosphatidylethanolamine in cell membranes and induce defects in Escherichia coli cell division.

Directory of Open Access Journals (Sweden)

Dagmar Zweytick

Full Text Available Two types of recently described antibacterial peptides derived from human lactoferricin, either nonacylated or N-acylated, were studied for their different interaction with membranes of Escherichia coli in vivo and in model systems. Electron microscopy revealed striking effects on the bacterial membrane as both peptide types induced formation of large membrane blebs. Electron and fluorescence microscopy, however demonstrated that only the N-acylated peptides partially induced the generation of oversized cells, which might reflect defects in cell-division. Further a different distribution of cardiolipin domains on the E. coli membrane was shown only in the presence of the N-acylated peptides. The lipid was distributed over the whole bacterial cell surface, whereas cardiolipin in untreated and nonacylated peptide-treated cells was mainly located at the septum and poles. Studies with bacterial membrane mimics, such as cardiolipin or phosphatidylethanolamine revealed that both types of peptides interacted with the negatively charged lipid cardiolipin. The nonacylated peptides however induced segregation of cardiolipin into peptide-enriched and peptide-poor lipid domains, while the N-acylated peptides promoted formation of many small heterogeneous domains. Only N-acylated peptides caused additional severe effects on the main phase transition of liposomes composed of pure phosphatidylethanolamine, while both peptide types inhibited the lamellar to hexagonal phase transition. Lipid mixtures of phosphatidylethanolamine and cardiolipin revealed anionic clustering by all peptide types. However additional strong perturbation of the neutral lipids was only seen with the N-acylated peptides. Nuclear magnetic resonance demonstrated different conformational arrangement of the N-acylated peptide in anionic and zwitterionic micelles revealing possible mechanistic differences in their action on different membrane lipids. We hypothesized that both peptides kill

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.

Principles of chemical kinetics

CERN Document Server

House, James E

2007-01-01

James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. ADRITY BAIDYA. Articles written in Journal of Chemical Sciences. Volume 130 Issue 4 April 2018 pp 35. Synthesis, characterization and antimicrobial studies of cadmium(II) complexes with a tetraazamacrocycle (LB) and its cyanoethyl N-pendent derivative (LBX) · MD SHAH ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. S Karthikeyan. Articles written in Journal of Chemical Sciences. Volume 113 Issue 4 August 2001 pp 245-256 Inorganic. Synthesis and physiochemical studies on binuclear Cu(II) complexes derived from 2,6-[(N-phenylpiperazin-1-yl)methyl]-4-substituted phenols.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Venkateswara Rao Anna. Articles written in Journal of Chemical Sciences. Volume 124 Issue 2 March 2012 pp 411-419. and - cyclic -perimeter hydrocarbon platinum group metal complexes of 3-(2-pyridyl)pyrazole derived ligands with a pendant nitrile group: Syntheses ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Jubaraj B Baruah. Articles written in Journal of Chemical Sciences. Volume 117 Issue 2 March 2005 pp 117-122. Synthesis, characterisation of few N-substituted 1,8-naphthalimide derivatives and their copper(II) complexes · Nilotpal Barooah Chandan Tamuly Jubaraj B ...

Innovations in Undergraduate Chemical Biology Education.

Science.gov (United States)

Van Dyke, Aaron R; Gatazka, Daniel H; Hanania, Mariah M

2018-01-19

Chemical biology derives intellectual vitality from its scientific interface: applying chemical strategies and perspectives to biological questions. There is a growing need for chemical biologists to synergistically integrate their research programs with their educational activities to become holistic teacher-scholars. This review examines how course-based undergraduate research experiences (CUREs) are an innovative method to achieve this integration. Because CUREs are course-based, the review first offers strategies for creating a student-centered learning environment, which can improve students' outcomes. Exemplars of CUREs in chemical biology are then presented and organized to illustrate the five defining characteristics of CUREs: significance, scientific practices, discovery, collaboration, and iteration. Finally, strategies to overcome common barriers in CUREs are considered as well as future innovations in chemical biology education.

Nitration of Thiacalix[4]arene Derivatives

Czech Academy of Sciences Publication Activity Database

Lhoták, P.; Svoboda, J.; Stibor, I.; Sýkora, Jan

2002-01-01

Roč. 43, č. 41 (2002), s. 7413-7417 ISSN 0040-4039 R&D Projects: GA ČR GA104/00/1722 Keywords : derivatives * nitation of thiacalix[4]arene Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.357, year: 2002

Chemical derivation to enhance the chemical/oxidative stability of resorcinol-formaldehyde (R-F) resin

International Nuclear Information System (INIS)

Hubler, T.L.; Shaw, W.J.; Brown, G.N.; Linehan, J.C.; Franz, J.A.; Hart, T.R.; Hogan, M.O.

1996-09-01

Tank wastes at Hanford and SRS contain highly alkaline supernate solutions of conc. Na, K nitrates with large amounts of 137 Cs. It is desirable to remove and concentrate the highly radioactive fraction for vitrification. One candidate ion exchange material for removing the radiocesium is R-F resin. This report summarizes studies into synthesis and characterization of 4-derivatized R-F resins prepared in pursuit of more chemically/oxidatively robust resin. 85% 4-fluororesorcinol/15% phenol formaldehyde resin appears to have good stability in alkaline solution, although there may be some nucleophilic displacement reaction during synthesis; further studies are needed

Chemical, computational and functional insights into the chemical stability of the Hedgehog pathway inhibitor GANT61.

Science.gov (United States)

Calcaterra, Andrea; Iovine, Valentina; Botta, Bruno; Quaglio, Deborah; D'Acquarica, Ilaria; Ciogli, Alessia; Iazzetti, Antonia; Alfonsi, Romina; Lospinoso Severini, Ludovica; Infante, Paola; Di Marcotullio, Lucia; Mori, Mattia; Ghirga, Francesca

2018-12-01

This work aims at elucidating the mechanism and kinetics of hydrolysis of GANT61, the first and most-widely used inhibitor of the Hedgehog (Hh) signalling pathway that targets Glioma-associated oncogene homologue (Gli) proteins, and at confirming the chemical nature of its bioactive form. GANT61 is poorly stable under physiological conditions and rapidly hydrolyses into an aldehyde species (GANT61-A), which is devoid of the biological activity against Hh signalling, and a diamine derivative (GANT61-D), which has shown inhibition of Gli-mediated transcription. Here, we combined chemical synthesis, NMR spectroscopy, analytical studies, molecular modelling and functional cell assays to characterise the GANT61 hydrolysis pathway. Our results show that GANT61-D is the bioactive form of GANT61 in NIH3T3 Shh-Light II cells and SuFu -/- mouse embryonic fibroblasts, and clarify the structural requirements for GANT61-D binding to Gli1. This study paves the way to the design of GANT61 derivatives with improved potency and chemical stability.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. PRADEEP KUMAR BUDDE. Articles written in Journal of Chemical Sciences. Volume 130 Issue 3 March 2018 pp 27. Non-oxidative methane dehydroaromatization reaction over highly active α-MoC1−x ZSM-5 derived from pretreatment · PRADEEP KUMAR BUDDE ARVIND ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Ruli Borah. Articles written in Journal of Chemical Sciences. Volume 123 Issue 5 September 2011 pp 623-630. Investigation of Prins reaction for the synthesis of 2, 4- disubstituted tetrahydropyran derivatives and 1, 3-dioxanes using polyaniline supported acid as reusable ...

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. ...

Undesired Plant-Derived Components in Food

NARCIS (Netherlands)

Dusemund, Birgit; Rietjens, Ivonne M.C.M.; Abraham, Klaus; Cartus, Alexander; Schrenk, Dieter

2017-01-01

Among the various chemical compounds, the class of natural plant-derived substances in the modern food chain is generating increasing concern. Adverse effects encountered may be various and pose risks of acute, subchronic, or chronic toxicity. The underlying mechanisms of toxicity may be

A complete set of NMR chemical shifts and spin-spin coupling constants for L-Alanyl-L-Alanine zwitterion and analysis of its conformational behavior

Czech Academy of Sciences Publication Activity Database

Bouř, Petr; Buděšínský, Miloš; Špirko, Vladimír; Kapitán, Josef; Šebestík, Jaroslav; Sychrovský, Vladimír

2005-01-01

Roč. 127, - (2005), 17079-17089 ISSN 0002-7863 R&D Projects: GA AV ČR(CZ) IAA4055104; GA ČR(CZ) GA203/05/0388 Institutional research plan: CEZ:AV0Z40550506 Keywords : NMR * chemical shifts * coupling constants Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.419, year: 2005

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.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Philippe Bertrand. Articles written in Journal of Chemical Sciences. Volume 121 Issue 4 July 2009 pp 471-479. Biological activities of substituted trichostatic acid derivatives · Cédric Charrier Joëlle Roche Jean-Pierre Gesson Philippe Bertrand · More Details Abstract Fulltext ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. XIANG WANG. Articles written in Journal of Chemical Sciences. Volume 129 Issue 1 January 2017 pp 9-20 Regular Article. Self-assembly, structures and properties of three new Ni(II) coordination polymers derived from two different bis-pyridyl-bis-amide ligands and two ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Hai-Liang Zhu. Articles written in Journal of Chemical Sciences. Volume 121 Issue 4 July 2009 pp 463-470. Synthesis, antimicrobial activity of lamotrigine and its ammonium derivatives · Yong Qian Peng-Cheng Lv Lei Shi Rui-Qin Fang Zhong-Cheng Song Hai-Liang Zhu.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Gameel A Baghaffar. Articles written in Journal of Chemical Sciences. Volume 121 Issue 6 November 2009 pp 983-987. Multifunctional switches based on bis-imidazole derivative · Abdullah M A Asiri Gameel A Baghaffar Khadija O Badahdah Abdullah G M Al-Sehemi Salman ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Cédric Charrier. Articles written in Journal of Chemical Sciences. Volume 121 Issue 4 July 2009 pp 471-479. Biological activities of substituted trichostatic acid derivatives · Cédric Charrier Joëlle Roche Jean-Pierre Gesson Philippe Bertrand · More Details Abstract Fulltext ...

Chemical Growth Regulators for Guayule Plants

Science.gov (United States)

Dastoor, M. N.; Schubert, W. W.; Petersen, G. R.

1982-01-01

Test Tubes containing Guayule - tissue cultures were used in experiments to test effects of chemical-growth regulators. The shoots grew in response to addition of 2-(3,4-dichlorophenoxy)-triethylamine (triethylamine (TEA) derivative) to agar medium. Preliminary results indicate that a class of compounds that promotes growth in soil may also promote growth in a culture medium. Further experiments are needed to define the effect of the TEA derivative.

Alternative derivations of the statistical mechanical distribution laws.

Science.gov (United States)

Wall, F T

1971-08-01

A new approach is presented for the derivation of statistical mechanical distribution laws. The derivations are accomplished by minimizing the Helmholtz free energy under constant temperature and volume, instead of maximizing the entropy under constant energy and volume. An alternative method involves stipulating equality of chemical potential, or equality of activity, for particles in different energy levels. This approach leads to a general statement of distribution laws applicable to all systems for which thermodynamic probabilities can be written. The methods also avoid use of the calculus of variations, Lagrangian multipliers, and Stirling's approximation for the factorial. The results are applied specifically to Boltzmann, Fermi-Dirac, and Bose-Einstein statistics. The special significance of chemical potential and activity is discussed for microscopic systems.

Sorption and Transport of Pharmaceutical chemicals in Organic- and Mineral-rich Soils

Science.gov (United States)

Vulava, V. M.; Schwindaman, J.; Murphey, V.; Kuzma, S.; Cory, W.

2011-12-01

Pharmaceutical, active ingredients in personal care products (PhACs), and their derivative compounds are increasingly ubiquitous in surface waters across the world. Sorption and transport of four relatively common PhACs (naproxen, ibuprofen, cetirizine, and triclosan) in different natural soils was measured. All of these compounds are relatively hydrophobic (log KOW>2) and have acid/base functional groups, including one compound that is zwitterionic (cetirizine.) The main goal of this study was to correlate organic matter (OM) and clay content in natural soils and sediment with sorption and degradation of PhACs and ultimately their potential for transport within the subsurface environment. A- and B-horizon soils were collected from four sub-regions within a pristine managed forested watershed near Charleston, SC, with no apparent sources of anthropogenic contamination. These four soil series had varying OM content (fOC) between 0.4-9%, clay mineral content between 6-20%, and soil pH between 4.5-6. The A-horizon soils had higher fOC and lower clay content than the B-horizon soils. Sorption isotherms measured from batch sorption experimental data indicated a non-linear sorption relationship in all A- and B-horizon soils - stronger sorption was observed at lower PhAC concentrations and lower sorption at higher concentrations. Three PhACs (naproxen, ibuprofen, and triclosan) sorbed more strongly with higher fOC A-horizon soils compared with the B-horizon soils. These results show that soil OM had a significant role in strongly binding these three PhACs, which had the highest KOW values. In contrast, cetirizine, which is predominantly positively charged at pH below 8, strongly sorbed to soils with higher clay mineral content and least strongly to higher fOC soils. All sorption isotherms fitted well to the Freundlich model. For naproxen, ibuprofen, and triclosan, there was a strong and positive linear correlation between the Freundlich adsorption constant, Kf, and f

Indium tin oxide with zwitterionic interfacial design for biosensing applications in complex matrices

Energy Technology Data Exchange (ETDEWEB)

Darwish, Nadia T.; Alias, Yatimah; Khor, Sook Mei, E-mail: naomikhor@um.edu.my

2015-01-15

Graphical abstract: - Highlights: • The incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. • The resistance to non-specific protein adsorptions of BSA–FITC and RBITC–Cyt c were determined by confocal laser scanning microscopy. • The antifouling interface allows detection of target analytes in highly complicated biological matrices. - Abstract: Biosensing interfaces consisting of linker molecules (COOH or NH{sub 2}) and charged, antifouling moieties ((-SO{sup 3−} and N{sup +}(Me){sub 3}) for biosensing applications were prepared for the first time by the in situ deposition of mixtures of aryl diazonium cations on indium tin oxide (ITO) electrodes. A linker molecule is required for the attachment of biorecognition molecules (e.g., antibodies, enzymes, DNA chains, and aptamers) close to the transducer surface. The attached molecules improve the biosensing sensitivity and also provide a short response time for analyte detection. Thus, the incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. The reductive adsorption behavior and electrochemical measurement were studied for (1) an individual compound and (2) a mixture of antifouling zwitterionic molecules together with linker molecules [combination 1: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 1,4-phenylenediamine (PPD); combination 2: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 4-aminobenzoic acid (PABA)] of aryl diazonium cations grafted onto an ITO electrode. The mixture ratios of SP:TMAP:PPD and SP:TMAP:PABA that provided the greatest resistance to non-specific protein adsorptions of bovine serum albumin labeled with fluorescein isothiocyanate (BSA–FITC) and cytochrome c labeled with rhodamine B isothiocyanate (RBITC–Cyt c) were determined by confocal laser scanning microscopy (CLSM). For the surface antifouling study

Indium tin oxide with zwitterionic interfacial design for biosensing applications in complex matrices

International Nuclear Information System (INIS)

Darwish, Nadia T.; Alias, Yatimah; Khor, Sook Mei

2015-01-01

Graphical abstract: - Highlights: • The incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. • The resistance to non-specific protein adsorptions of BSA–FITC and RBITC–Cyt c were determined by confocal laser scanning microscopy. • The antifouling interface allows detection of target analytes in highly complicated biological matrices. - Abstract: Biosensing interfaces consisting of linker molecules (COOH or NH 2 ) and charged, antifouling moieties ((-SO 3− and N + (Me) 3 ) for biosensing applications were prepared for the first time by the in situ deposition of mixtures of aryl diazonium cations on indium tin oxide (ITO) electrodes. A linker molecule is required for the attachment of biorecognition molecules (e.g., antibodies, enzymes, DNA chains, and aptamers) close to the transducer surface. The attached molecules improve the biosensing sensitivity and also provide a short response time for analyte detection. Thus, the incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. The reductive adsorption behavior and electrochemical measurement were studied for (1) an individual compound and (2) a mixture of antifouling zwitterionic molecules together with linker molecules [combination 1: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 1,4-phenylenediamine (PPD); combination 2: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 4-aminobenzoic acid (PABA)] of aryl diazonium cations grafted onto an ITO electrode. The mixture ratios of SP:TMAP:PPD and SP:TMAP:PABA that provided the greatest resistance to non-specific protein adsorptions of bovine serum albumin labeled with fluorescein isothiocyanate (BSA–FITC) and cytochrome c labeled with rhodamine B isothiocyanate (RBITC–Cyt c) were determined by confocal laser scanning microscopy (CLSM). For the surface antifouling study, we used 2

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Yuanming Zhang. Articles written in Journal of Chemical Sciences. Volume 118 Issue 3 May 2006 pp 281-285. Temperature effects on surface activity and application in oxidation of toluene derivatives of CTAB-SDS with KMnO4 · Yu Tang Biying Du Jun Yang Yuanming ...

A chemical specialty semantic network for the Unified Medical Language System

Directory of Open Access Journals (Sweden)

Morrey C

2012-05-01

Full Text Available Abstract Background Terms representing chemical concepts found the Unified Medical Language System (UMLS are used to derive an expanded semantic network with mutually exclusive semantic types. The UMLS Semantic Network (SN is composed of a collection of broad categories called semantic types (STs that are assigned to concepts. Within the UMLS’s coverage of the chemical domain, we find a great deal of concepts being assigned more than one ST. This leads to the situation where the extent of a given ST may contain concepts elaborating variegated semantics. A methodology for expanding the chemical subhierarchy of the SN into a finer-grained categorization of mutually exclusive types with semantically uniform extents is presented. We call this network a Chemical Specialty Semantic Network (CSSN. A CSSN is derived automatically from the existing chemical STs and their assignments. The methodology incorporates a threshold value governing the minimum size of a type’s extent needed for inclusion in the CSSN. Thus, different CSSNs can be created by choosing different threshold values based on varying requirements. Results A complete CSSN is derived using a threshold value of 300 and having 68 STs. It is used effectively to provide high-level categorizations for a random sample of compounds from the “Chemical Entities of Biological Interest” (ChEBI ontology. The effect on the size of the CSSN using various threshold parameter values between one and 500 is shown. Conclusions The methodology has several potential applications, including its use to derive a pre-coordinated guide for ST assignments to new UMLS chemical concepts, as a tool for auditing existing concepts, inter-terminology mapping, and to serve as an upper-level network for ChEBI.

Intramolecular cascade rearrangements of enynamine derived ketenimines: access to acyclic and cyclic amidines.

Science.gov (United States)

Chauhan, Dinesh Pratapsinh; Varma, Sreejith J; Gudem, Mahesh; Panigrahi, Nihar; Singh, Khushboo; Hazra, Anirban; Talukdar, Pinaki

2017-06-07

Copper-catalyzed reaction of enynamines with sulfonylazides provides acyclic and cyclic amidines. Nucleophilic addition of the tethered amino group on the in situ generated ketenimine forms a six-membered cyclic zwitterionic intermediate which facilitates migration of the tethered amino group to the C 5 -center giving the acyclic amidine. On the other hand, migration of a substituent on the amino group to C 2 - and C 4 -centers results in the formation of cyclic amidines. Computational studies were carried out to validate the mechanism which indicates that the product distribution of the process depends on the substitutions on the enynamine backbone.

Recent updates on lignocellulosic biomass derived ethanol - A review

Directory of Open Access Journals (Sweden)

Rajeev Kumar

2016-03-01

Full Text Available Lignocellulosic (or cellulosic biomass derived ethanol is the most promising near/long term fuel candidate. In addition, cellulosic biomass derived ethanol may serve a precursor to other fuels and chemicals that are currently derived from unsustainable sources and/or are proposed to be derived from cellulosic biomass. However, the processing cost for second generation ethanol is still high to make the process commercially profitable and replicable. In this review, recent trends in cellulosic biomass ethanol derived via biochemical route are reviewed with main focus on current research efforts that are being undertaken to realize high product yields/titers and bring the overall cost down.

Isocyanate leading to Guanidines/Urea derivatives formation

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 6. Zinc catalyzed Guanylation reaction of Amines with Carbodiimides/ Isocyanate leading to Guanidines/Urea derivatives formation. JAYEETA BHATTACHARJEE MITALI SACHDEVA INDRANI BANERJEE TARUN K PANDA. Regular Article Volume 128 ...

Langmuir-Blodgett Films of Graphene Derivatives

DEFF Research Database (Denmark)

Petersen, Søren Vermehren

The work presented in this PhD thesis can be divided into two main categories: 1) Syn-thesis and Langmuir-Blodgett assembly of graphene derivatives and 2) Application and characterization of graphene derivatives as an interface material in molecular electron-ics. While the first category could...... be divided further, the synthesis and Langmuir-Blodgett results are intertwined in such a way that it would be more confusing to pre-sent them separately. The Langmuir-Blodgett deposition also played a crucial, but more isolated, part in the investigation of graphene derivatives as interface material....... Solution processable graphene in the form of chemically derived graphene has been synthesized through the modified Hummers method with subsequent reduction into reduced graphene oxide with hydrazine. The completeness of oxidation, the effect of the refinement steps and the reduction of the graphene oxide...

System and process for capture of acid gasses at elevated pressure from gaseous process streams

Science.gov (United States)

Heldebrant, David J.; Koech, Phillip K.; Linehan, John C.; Rainbolt, James E.; Bearden, Mark D.; Zheng, Feng

2016-09-06

A system, method, and material that enables the pressure-activated reversible chemical capture of acid gasses such as CO.sub.2 from gas volumes such as streams, flows or any other volume. Once the acid gas is chemically captured, the resulting product typically a zwitterionic salt, can be subjected to a reduced pressure whereupon the resulting product will release the captures acid gas and the capture material will be regenerated. The invention includes this process as well as the materials and systems for carrying out and enabling this process.

Fabrication of corona-free nanoparticles with tunable hydrophobicity.

Science.gov (United States)

Moyano, Daniel F; Saha, Krishnendu; Prakash, Gyan; Yan, Bo; Kong, Hao; Yazdani, Mahdieh; Rotello, Vincent M

2014-07-22

A protein corona is formed at the surface of nanoparticles in the presence of biological fluids, masking the surface properties of the particle and complicating the relationship between chemical functionality and biological effects. We present here a series of zwitterionic NPs of variable hydrophobicity that do not adsorb proteins at moderate levels of serum protein and do not form hard coronas at physiological serum concentrations. These particles provide platforms to evaluate nanobiological behavior such as cell uptake and hemolysis dictated directly by chemical motifs at the nanoparticle surface.

Effect of static mixer on the performance of compact plate heat exchanger with zwitterionic type of drag-reducing additives

Energy Technology Data Exchange (ETDEWEB)

Blais, C.; Wollerstrand, J.

1997-06-01

The main task of the project was to investigate the influence of drag-reducing additives (DRA) dissolved in circulating hot water on heat transfer in compact plate heat exchangers (PHE). Furthermore the result of flow disturbance (static mixing) immediately before the PHE on pressure drop and heat transfer was clarified. The project used a new type of DRA (surfactants of zwitterionic type) for two different temperature ranges. A dedicated test rig, `Ansgar`, was built for the purpose. Good thermal and mechanical stability also outside the operating range was observed except some sensitivity for water hardness at high temperatures for DRA2. Similarly to known investigations, the heat transfer coefficient was significantly reduced by DRA in heat exchangers. In PHE used however, the heat transfer reduction was considerably lower in the high flow region. A static mixer placed in front of the PHE was found to significantly improve heat transfer, especially at high flow rates. On the other hand, an additional pressure drop was introduced. Therefore the optimal choice of static mixer needs further investigation. Specially designed PHE combining mixing and heat transfer functions could be beneficial to reducing the effects of additives in thermal systems. The relaxation time (RT) of drag-reducing additives in water solutions flowing through test pipes with known geometries was estimated by monitoring specific pressure drop variation along the pipe. These preliminary experiments in respect to relaxation time showed that RT depends on the flow rate and on the temperature 12 refs, 11 figs, 1 tab

Two-Dimensional MoS2-Based Zwitterionic Hydrophilic Interaction Liquid Chromatography Material for the Specific Enrichment of Glycopeptides.

Science.gov (United States)

Xia, Chaoshuang; Jiao, Fenglong; Gao, Fangyuan; Wang, Heping; Lv, Yayao; Shen, Yehua; Zhang, Yangjun; Qian, Xiaohong

2018-06-05

Mass spectrometry (MS)-based glycoproteomics research requires highly efficient sample preparation to eliminate interference from non-glycopeptides and to improve the efficiency of glycopeptide detection. In this work, a novel MoS 2 /Au-NP (gold nanoparticle)-L-cysteine nanocomposite was prepared for glycopeptide enrichment. The two-dimensional (2D) structured MoS 2 nanosheets served as a matrix that could provide a large surface area for immobilizing hydrophilic groups (such as L-cysteine) with low steric hindrance between the materials and the glycopeptides. As a result, the novel nanomaterial possessed an excellent ability to capture glycopeptides. Compared to commercial zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) materials, the novel nanomaterials exhibited excellent enrichment performance with ultrahigh selectivity and sensitivity (approximately 10 fmol), high binding capacity (120 mg g -1 ), high enrichment recovery (more than 93%), satisfying batch-to-batch reproducibility, and good universality for glycopeptide enrichment. In addition, its outstanding specificity and efficiency for glycopeptide enrichment was confirmed by the detection of glycopeptides from an human serum immunoglobulin G (IgG) tryptic digest in quantities as low as a 1:1250 molar ratio of IgG tryptic digest to bovine serum albumin tryptic digest. The novel nanocomposites were further used for the analysis of complex samples, and 1920 glycopeptide backbones from 775 glycoproteins were identified in three replicate analyses of 50 μg of proteins extracted from HeLa cell exosomes. The resulting highly informative mass spectra indicated that this multifunctional nanomaterial-based enrichment method could be used as a promising tool for the in-depth and comprehensive characterization of glycoproteomes in MS-based glycoproteomics.

Bioalerts: a python library for the derivation of structural alerts from bioactivity and toxicity data sets.

Science.gov (United States)

Cortes-Ciriano, Isidro

2016-01-01

Assessing compound toxicity at early stages of the drug discovery process is a crucial task to dismiss drug candidates likely to fail in clinical trials. Screening drug candidates against structural alerts, i.e. chemical fragments associated to a toxicological response prior or after being metabolized (bioactivation), has proved a valuable approach for this task. During the last decades, diverse algorithms have been proposed for the automatic derivation of structural alerts from categorical toxicity data sets. Here, the python library bioalerts is presented, which comprises functionalities for the automatic derivation of structural alerts from categorical (dichotomous), e.g. toxic/non-toxic, and continuous bioactivity data sets, e.g. [Formula: see text] or [Formula: see text] values. The library bioalerts relies on the RDKit implementation of the circular Morgan fingerprint algorithm to compute chemical substructures, which are derived by considering radial atom neighbourhoods of increasing bond radius. In addition to the derivation of structural alerts, bioalerts provides functionalities for the calculation of unhashed (keyed) Morgan fingerprints, which can be used in predictive bioactivity modelling with the advantage of allowing for a chemically meaningful deconvolution of the chemical space. Finally, bioalerts provides functionalities for the easy visualization of the derived structural alerts.

Optical Fiber Chemical Sensor with Sol-Gel Derived Refractive Material as Transducer for High Temperature Gas Sensing in Clean Coal Technology

Energy Technology Data Exchange (ETDEWEB)

Shiquan Tao

2006-12-31

The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties of sol-gel derived materials in ambient and high temperature gases have been studied by using fiber optic spectroscopic techniques, such as fiber optic ultraviolet/visible absorption spectrometry, fiber optic near infrared absorption spectrometry and fiber optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of

Chemicals from Biomass: A Market Assessment of Bioproducts with Near-Term Potential

Energy Technology Data Exchange (ETDEWEB)

Biddy, Mary J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scarlata, Christopher [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kinchin, Christopher [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-03-23

Production of chemicals from biomass offers a promising opportunity to reduce U.S. dependence on imported oil, as well as to improve the overall economics and sustainability of an integrated biorefinery. Given the increasing momentum toward the deployment and scale-up of bioproducts, this report strives to: (1) summarize near-term potential opportunities for growth in biomass-derived products; (2) identify the production leaders who are actively scaling up these chemical production routes; (3) review the consumers and market champions who are supporting these efforts; (4) understand the key drivers and challenges to move biomass-derived chemicals to market; and (5) evaluate the impact that scale-up of chemical strategies will have on accelerating the production of biofuels.

Derivative spectrophotometry applied to solutions of complex composition

International Nuclear Information System (INIS)

Perfil'ev, V.A.

1986-01-01

The authors consider not only the basic principles of derivative spectrophotometry but also survey the data on its use in research on the properties of materials, the compositions of compounds, and the structures of complex chemical systems. Recording methods by which derivative spectra can be generated include descriptions of electronic differentiation, computer spectrum differentiation, wavelength modulation, and the two-way derivative method. A section on the advantages of derivative spectrophotometry presents a discussion on features enabling one to determine various substances from their characteristic absorption spectra without performing complicated operations to isolate or separate the components. Other topics include research on the structures of substances and metal-ion complexing in solutions, derivative spectrophotometry in gas analysis, gas determination, and determining organic and compounds

Chemical removal of radionuclides in contaminated spinach derived from the Fukushima nuclear accident

International Nuclear Information System (INIS)

Shiba, Kazuhiro; Kitamura, Yoji; Kozaka, Takashi; Uno, Izumi; Miyoshi, Hirokazu; Yanaga, Makoto

2012-01-01

We examined a simple and effective removal method for contaminated farm products to ensure the relief of farmers and the security of consumers. Removal of radionuclides from spinach by chemical methods was investigated. The result of chemical removal showed that antioxidant agents removed radionuclides from spinach by 70–80% for 131 I and more than 80% for radiocesium. In particular, ascorbic acid is promising as a safe and versatile option. (author)

A mathematical basis for plant patterning derived from physico-chemical phenomena.

Science.gov (United States)

Beleyur, Thejasvi; Abdul Kareem, Valiya Kadavu; Shaji, Anil; Prasad, Kalika

2013-04-01

The position of leaves and flowers along the stem axis generates a specific pattern, known as phyllotaxis. A growing body of evidence emerging from recent computational modeling and experimental studies suggests that regulators controlling phyllotaxis are chemical, e.g. the plant growth hormone auxin and its dynamic accumulation pattern by polar auxin transport, and physical, e.g. mechanical properties of the cell. Here we present comprehensive views on how chemical and physical properties of cells regulate the pattern of leaf initiation. We further compare different computational modeling studies to understand their scope in reproducing the observed patterns. Despite a plethora of experimental studies on phyllotaxis, understanding of molecular mechanisms of pattern initiation in plants remains fragmentary. Live imaging of growth dynamics and physicochemical properties at the shoot apex of mutants displaying stable changes from one pattern to another should provide mechanistic insights into organ initiation patterns. Copyright © 2013 WILEY Periodicals, Inc.

Spasmogenic, Spasmolytic and Chemical Screening of Cigarettes

African Journals Online (AJOL)

guloona

The aqueous and ethanolic extracts derived from cigarettes (Morven Gold) were screened for chemicals ... Pakistan, oral cancer is the second most common cancer ... E-mail: naveedjia@yahoo.com, naveedullahpharmacist@gmail.com.

Melamine derivatives as effective corrosion inhibitors for mild steel in acidic solution: Chemical, electrochemical, surface and DFT studies

Science.gov (United States)

Verma, Chandrabhan; Haque, J.; Ebenso, Eno E.; Quraishi, M. A.

2018-06-01

In present study two condensation products of melamine (triazine) and glyoxal namely, 2,2-bis(4,6-diamino-1,3,5-triazin-2-ylamino)acetaldehyde (ME-1) and (N2,N2‧E,N2,N2‧E)-N2,N2‧-(ethane-1,2-diylidene)-bis-(1,3,5-triazine-2,4,6-triamine) (ME-2) are tested as mild steel corrosion inhibitors in acidic solution (1M HCl). The inhibition efficiency of ME-1 and ME-2 increases with increase in their concentrations and maximum values of 91.47% and 94.88% were derived, respectively at 100 mgL-1 (34.20 × 10-5 M) concentration. Adsorption of ME-1 and ME-2 on the surface of metal obeyed the Langmuir adsorption isotherm. Polarization investigation revealed that ME-1 and ME-2 act as mixed type inhibitors with minor cathodic prevalence. The chemical and electrochemical analyses also supported by surface characterization methods where significant smoothness in the surface morphologies was observed in the images of SEM and AFM spectra. Several DFT indices such as EHOMO and ELUMO, ΔE, η, σ, χ, μ and ΔN were derived for both ME-1 and ME-2 molecules and correlated with experimental results. The DFT studies have also been carried out for protonated or cationic form of the inhibitor molecules by considering that in acidic medium the heteroatoms of organic inhibitors easily undergo protonation. The experimental and density functional theory (DFT) studies (neutral and protonated) were in good agreement.

[The recent development of fiber-optic chemical sensor].

Science.gov (United States)

Wang, Jian; Wei, Jian-ping; Yang, Bo; Gao, Zhi-yang; Zhang, Li-wei; Yang, Xue-feng

2014-08-01

The present article provides a brief review of recent research on fiber-optic chemical sensor technology and the future development trends. Especially, fiber-optic pH chemical sensor, fiber-optic ion chemicl sensor, and fiber-optic gas chemical sensor are introduced respectively. Sensing film preparation methods such as chemical bonding method and sol-gel method were briefly reviewed. The emergence of new type fiber-microstructured optical fiber opened up a new development direction for fiber-optic chemical sensor. Because of its large inner surface area, flexible design of structure, having internal sensing places in fibers, it has rapidly become an important development direction and research focus of the fiber-optic chemical sensors. The fiber-optic chemical sensor derived from microstructured optical fiber is also discussed in detail. Finally, we look to the future of the fiber-optic chemical sensor.

Novel amphiphilic poly(dimethylsiloxane) based polyurethane networks tethered with carboxybetaine and their combined antibacterial and anti-adhesive property

Energy Technology Data Exchange (ETDEWEB)

Jiang, Jingxian; Fu, Yuchen; Zhang, Qinghua, E-mail: qhzhang@zju.edu.cn; Zhan, Xiaoli; Chen, Fengqiu

2017-08-01

Highlights: • An amphiphilic poly(dimethylsiloxane) (PDMS) based polyurethane (PU) network tethered with carboxybetaine is prepared. • The surface distribution of PDMS and zwitterionic segments produces an obvious amphiphilic heterogeneous surface. • This designed PDMS-based amphiphilic PU network exhibits combined antibacterial and anti-adhesive properties. - Abstract: The traditional nonfouling materials are powerless against bacterial cells attachment, while the hydrophobic bactericidal surfaces always suffer from nonspecific protein adsorption and dead bacterial cells accumulation. Here, amphiphilic polyurethane (PU) networks modified with poly(dimethylsiloxane) (PDMS) and cationic carboxybetaine diol through simple crosslinking reaction were developed, which had an antibacterial efficiency of 97.7%. Thereafter, the hydrolysis of carboxybetaine ester into zwitterionic groups brought about anti-adhesive properties against bacteria and proteins. The surface chemical composition and wettability performance of the PU network surfaces were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle analysis. The surface distribution of PDMS and zwitterionic segments produced an obvious amphiphilic heterogeneous surface, which was demonstrated by atomic force microscopy (AFM). Enzyme-linked immunosorbent assays (ELISA) were used to test the nonspecific protein adsorption behaviors. With the advantages of the transition from excellent bactericidal performance to anti-adhesion and the combination of fouling resistance and fouling release property, the designed PDMS-based amphiphilic PU network shows great application potential in biomedical devices and marine facilities.

Stability of sonicated aqueous suspensions of phospholipids under air.

Science.gov (United States)

Almog, R; Forward, R; Samsonoff, C

1991-12-01

The stability of phospholipids in liposomal aqueous suspension against oxidative degradation in air was investigated using spectrophotometric indices, glutathione peroxidase reactivity and thin layer chromatography. Zwitterionic phospholipid was found to be susceptible to degradation via oxidation of polyunsaturated hydrocarbon chains and ester hydrolysis, producing oxidized lysophosphatide and free fatty acid derivatives. These products were characterized as hydroperoxides based on their reactivity with the selenium-dependent glutathione peroxidase isolated from human erythrocytes. Lecithin in Tris buffer was more resistant to hydrolysis than in water. The sonication of 8.0 mM of soybean phosphatidylcholine (SB-PC) suspension in 0.1 M Tris (pH 7.5) in the presence of air produced relatively high concentration of conjugated diene hydroperoxide, but a small amount of hydrolyzed products. Anionic phospholipids, such as egg-phosphatidylglycerol (egg-PG), demonstrated higher resistance to air oxidation than the zwitterionic lecithin, but its oxidation was promoted by sonication.

Emergency management of chemical weapons injuries.

Science.gov (United States)

Anderson, Peter D

2012-02-01

The potential for chemical weapons to be used in terrorism is a real possibility. Classes of chemical weapons include nerve agents, vesicants (blister agents), choking agents, incapacitating agents, riot control agents, blood agents, and toxic industrial chemicals. The nerve agents work by blocking the actions of acetylcholinesterase leading to a cholinergic syndrome. Nerve agents include sarin, tabun, VX, cyclosarin, and soman. The vesicants include sulfur mustard and lewisite. The vesicants produce blisters and also damage the upper airways. Choking agents include phosgene and chlorine gas. Choking agents cause pulmonary edema. Incapacitating agents include fentanyl and its derivatives and adamsite. Riot control agents include Mace and pepper spray. Blood agents include cyanide. The mechanism of toxicity for cyanide is blocking oxidative phosphorylation. Toxic industrial chemicals include agents such as formaldehyde, hydrofluoric acid, and ammonia.

Chemical modifications of Sterculia foetida L. oil to branched ester derivatives

NARCIS (Netherlands)

Manurung, Robert; Daniel, Louis; van de Bovenkamp, Hendrik H.; Buntara, Teddy; Maemunah, Siti; Kraai, Gerard; Makertihartha, I. G. B. N.; Broekhuis, Antonius A.; Heeres, Hero J.

An experimental study to modify Sterculia foetida L. oil (STO) or the corresponding methyl esters (STO FAME) to branched ester derivatives is reported. The transformations involve conversion of the cyclopropene rings in the fatty acid chains of STO through various catalytic as well as stoichiometric

Primary cilia: the chemical antenna regulating human adipose-derived stem cell osteogenesis.

Directory of Open Access Journals (Sweden)

Josephine C Bodle

Full Text Available Adipose-derived stem cells (ASC are multipotent stem cells that show great potential as a cell source for osteogenic tissue replacements and it is critical to understand the underlying mechanisms of lineage specification. Here we explore the role of primary cilia in human ASC (hASC differentiation. This study focuses on the chemosensitivity of the primary cilium and the action of its associated proteins: polycystin-1 (PC1, polycystin-2 (PC2 and intraflagellar transport protein-88 (IFT88, in hASC osteogenesis. To elucidate cilia-mediated mechanisms of hASC differentiation, siRNA knockdown of PC1, PC2 and IFT88 was performed to disrupt cilia-associated protein function. Immunostaining of the primary cilium structure indicated phenotypic-dependent changes in cilia morphology. hASC cultured in osteogenic differentiation media yielded cilia of a more elongated conformation than those cultured in expansion media, indicating cilia-sensitivity to the chemical environment and a relationship between the cilium structure and phenotypic determination. Abrogation of PC1, PC2 and IFT88 effected changes in both hASC proliferation and differentiation activity, as measured through proliferative activity, expression of osteogenic gene markers, calcium accretion and endogenous alkaline phosphatase activity. Results indicated that IFT88 may be an early mediator of the hASC differentiation process with its knockdown increasing hASC proliferation and decreasing Runx2, alkaline phosphatase and BMP-2 mRNA expression. PC1 and PC2 knockdown affected later osteogenic gene and end-product expression. PC1 knockdown resulted in downregulation of alkaline phosphatase and osteocalcin gene expression, diminished calcium accretion and reduced alkaline phosphatase enzymatic activity. Taken together our results indicate that the structure of the primary cilium is intimately associated with the process of hASC osteogenic differentiation and that its associated proteins are critical

Modeling of chemical reactions in micelle: water-mediated keto-enol interconversion as a case study.

Science.gov (United States)

Marracino, Paolo; Amadei, Andrea; Apollonio, Francesca; d'Inzeo, Guglielmo; Liberti, Micaela; di Crescenzo, Antonello; Fontana, Antonella; Zappacosta, Romina; Aschi, Massimiliano

2011-06-30

The effect of a zwitterionic micelle environment on the efficiency of the keto-enol interconversion of 2-phenylacetylthiophene has been investigated by means of a joint application of experimental and theoretical/computational approaches. Results have revealed a reduction of the reaction rate constant if compared with bulk water essentially because of the different solvation conditions experienced by the reactant species, including water molecules, in the micelle environment. The slight inhibiting effect due to the application of a static electric field has also been theoretically investigated and presented.

Next-generation text-mining mediated generation of chemical response-specific gene sets for interpretation of gene expression data

Directory of Open Access Journals (Sweden)

Hettne Kristina M

2013-01-01

Full Text Available Abstract Background Availability of chemical response-specific lists of genes (gene sets for pharmacological and/or toxic effect prediction for compounds is limited. We hypothesize that more gene sets can be created by next-generation text mining (next-gen TM, and that these can be used with gene set analysis (GSA methods for chemical treatment identification, for pharmacological mechanism elucidation, and for comparing compound toxicity profiles. Methods We created 30,211 chemical response-specific gene sets for human and mouse by next-gen TM, and derived 1,189 (human and 588 (mouse gene sets from the Comparative Toxicogenomics Database (CTD. We tested for significant differential expression (SDE (false discovery rate -corrected p-values Results Next-gen TM-derived gene sets matching the chemical treatment were significantly altered in three GE data sets, and the corresponding CTD-derived gene sets were significantly altered in five GE data sets. Six next-gen TM-derived and four CTD-derived fibrate gene sets were significantly altered in the PPARA knock-out GE dataset. None of the fibrate signatures in cMap scored significant against the PPARA GE signature. 33 environmental toxicant gene sets were significantly altered in the triazole GE data sets. 21 of these toxicants had a similar toxicity pattern as the triazoles. We confirmed embryotoxic effects, and discriminated triazoles from other chemicals. Conclusions Gene set analysis with next-gen TM-derived chemical response-specific gene sets is a scalable method for identifying similarities in gene responses to other chemicals, from which one may infer potential mode of action and/or toxic effect.

Radiation processing of chitosan derivative and its characteristics

International Nuclear Information System (INIS)

Kamarudin Bahari; Kamarolzaman Hussein; Kamaruddin Hashim; Khairul Zaman Mohd Dahlan

2002-01-01

Chitosan is natural polymer derived from chitin, a polysaccharide found in the exoskeleton of shrimps, crabs, fungi and others. Chitosan is a naturally occurring substance that is chemically similar to cellulose. Chitosan possesses a positive ionic charge give ability to chemically bond with negatively charged fats. Chitosan is soluble in organic acid but insoluble in water. Carboxymethyl-chitosan (cm-chitosan) is a derivative of chitosan which is water-soluble was then prepared by a carboxymethylation process of chitosan produced from local shrimp shell. A simple method for synthesis of cm-chitosan has been developed at 55 degree C in aqueous sodium hydroxide / propanol with chloroacetic acid (CAA) or sodium chloroacetate salt (SCA). The modification of chitosan to water-soluble chitosan can be used in hydrogel as anti-bacterial agent and it overcome the problem of bad smell using acetic acid. (Author)

Next-generation text-mining mediated generation of chemical response-specific gene sets for interpretation of gene expression data

Science.gov (United States)

2013-01-01

Background Availability of chemical response-specific lists of genes (gene sets) for pharmacological and/or toxic effect prediction for compounds is limited. We hypothesize that more gene sets can be created by next-generation text mining (next-gen TM), and that these can be used with gene set analysis (GSA) methods for chemical treatment identification, for pharmacological mechanism elucidation, and for comparing compound toxicity profiles. Methods We created 30,211 chemical response-specific gene sets for human and mouse by next-gen TM, and derived 1,189 (human) and 588 (mouse) gene sets from the Comparative Toxicogenomics Database (CTD). We tested for significant differential expression (SDE) (false discovery rate -corrected p-values sets and the CTD-derived gene sets in gene expression (GE) data sets of five chemicals (from experimental models). We tested for SDE of gene sets for six fibrates in a peroxisome proliferator-activated receptor alpha (PPARA) knock-out GE dataset and compared to results from the Connectivity Map. We tested for SDE of 319 next-gen TM-derived gene sets for environmental toxicants in three GE data sets of triazoles, and tested for SDE of 442 gene sets associated with embryonic structures. We compared the gene sets to triazole effects seen in the Whole Embryo Culture (WEC), and used principal component analysis (PCA) to discriminate triazoles from other chemicals. Results Next-gen TM-derived gene sets matching the chemical treatment were significantly altered in three GE data sets, and the corresponding CTD-derived gene sets were significantly altered in five GE data sets. Six next-gen TM-derived and four CTD-derived fibrate gene sets were significantly altered in the PPARA knock-out GE dataset. None of the fibrate signatures in cMap scored significant against the PPARA GE signature. 33 environmental toxicant gene sets were significantly altered in the triazole GE data sets. 21 of these toxicants had a similar toxicity pattern as the

Pesticides: chemicals for survival

International Nuclear Information System (INIS)

Lindquist, D.A.

1981-01-01

Pesticides are chemicals used to control pests such as insects, weeds, plant diseases, nematodes, and rodents. The increased use of pesticides since 1945 has greatly aided the increase in crop production, protected livestock from diseases such as trypanosomiasis, protected man from diseases such as malaria and filarisis, decreased losses of stored grain, and has generally improved man's welfare. Despite the enormous benefits derived from pesticides these chemicals are not problem-free. Many pesticides are toxic to living organisms and interfere with specific biochemical systems. To measure the very small quantities of a pesticide radiolabelled chemicals are frequently essential, particularly to measure changes in the chemical structure of the pesticide, movement of the pesticide in soil, plants, or animals, amounts of pesticide going through various steps in food processing, etc. The use of radiolabelled pesticides is shortly shown for metabolism of the pesticide in crop species, metabolism in ruminant, in chickens and eggs, in soil, and possibly leaching and sorption in soil, hydrolysis, bio-concentration, microbial and photodegradation, and toxicity studies

The chemical composition of the Wolf-Rayet stars

International Nuclear Information System (INIS)

Willis, A.J.

1982-01-01

This review summarises current knowledge of the chemical composition of PopI WR stars, concentrating on work carried out in this area since the last IAU, No. 49, symposium devoted to this stellar class (Bappu and Sahade 1973). Section 2 deals with an assessment of the atmospheric H/He ratio in both WN and WC stars: a parameter of fundamental importance in addressing their evolutionary status, as well as providing a base species with which to compare other derived chemical abundances. Section 3 briefly deals with the models generally employed and gives recent results for He, C and N abundances derived from both visible and UV line analyses. Section 4 summarises recent results from stellar evolutionary theory and in Section 5 these are compared with those derived from observation, assessing the significance of these new results and their implications for the evolutionary status of the WR stars. Some areas for further advancement are identified. (Auth.)

Human Stem Cell Derived Cardiomyocytes: An Alternative ...

Science.gov (United States)

Chemical spills and associated deaths in the US has increased 2.6-fold and 16-fold from 1983 to 2012, respectfully. In addition, the number of chemicals to which humans are exposed to in the environment has increased almost 10-fold from 2001 to 2013 within the US. Internationally, a WHO report on the global composite impact of chemicals on health reported that 16% of the total burden of cardiovascular disease was attributed to environmental chemical exposure with 2.5 million deaths per year. Clearly, the cardiovascular system, at all its various developmental and life stages, represents a critical target organ system that can be adversely affected by existing and emerging chemicals (e.g., engineered nanomaterials) in a variety of environmental media. The ability to assess chemical cardiac risk and safety is critically needed but extremely challenging due to the number and categories of chemicals in commerce, as indicated. This presentation\\session will evaluate the use of adult human stem cell derived cardiomyocytes, and existing platforms, as an alternative model to evaluate environmental chemical cardiac toxicity as well as provide key information for the development of predictive adverse outcomes pathways associated with environmental chemical exposures. (This abstract does not represent EPA policy) Rapid and translatable chemical safety screening models for cardiotoxicity current status for informing regulatory decisions, a workshop sponsored by the Society

Responding to the colourful use of chemicals in nineteenth-century food

OpenAIRE

Cobbold, Carolyn

2017-01-01

The paper explores how chemists tried to deal with one of the first examples of mass-produced industrial chemicals to enter daily life, through investigating the use of coal-tar derived dyes to colour food in the late nineteenth century. From the mid 1850s European chemists manufactured a range of new chemicals included drugs, dyes, scents and flavourings from the derivatives of coal-tar waste. Initially greeted by the nineteenth-century press and public as ‘wonder dyes’, the vibrant new colo...

Nanomaterials derived from metal-organic frameworks

Science.gov (United States)

Dang, Song; Zhu, Qi-Long; Xu, Qiang

2018-01-01

The thermal transformation of metal-organic frameworks (MOFs) generates a variety of nanostructured materials, including carbon-based materials, metal oxides, metal chalcogenides, metal phosphides and metal carbides. These derivatives of MOFs have characteristics such as high surface areas, permanent porosities and controllable functionalities that enable their good performance in sensing, gas storage, catalysis and energy-related applications. Although progress has been made to tune the morphologies of MOF-derived structures at the nanometre scale, it remains crucial to further our knowledge of the relationship between morphology and performance. In this Review, we summarize the synthetic strategies and optimized methods that enable control over the size, morphology, composition and structure of the derived nanomaterials. In addition, we compare the performance of materials prepared by the MOF-templated strategy and other synthetic methods. Our aim is to reveal the relationship between the morphology and the physico-chemical properties of MOF-derived nanostructures to optimize their performance for applications such as sensing, catalysis, and energy storage and conversion.

Scaling up of renewable chemicals.

Science.gov (United States)

Sanford, Karl; Chotani, Gopal; Danielson, Nathan; Zahn, James A

2016-04-01

The transition of promising technologies for production of renewable chemicals from a laboratory scale to commercial scale is often difficult and expensive. As a result the timeframe estimated for commercialization is typically underestimated resulting in much slower penetration of these promising new methods and products into the chemical industries. The theme of 'sugar is the next oil' connects biological, chemical, and thermochemical conversions of renewable feedstocks to products that are drop-in replacements for petroleum derived chemicals or are new to market chemicals/materials. The latter typically offer a functionality advantage and can command higher prices that result in less severe scale-up challenges. However, for drop-in replacements, price is of paramount importance and competitive capital and operating expenditures are a prerequisite for success. Hence, scale-up of relevant technologies must be interfaced with effective and efficient management of both cell and steel factories. Details involved in all aspects of manufacturing, such as utilities, sterility, product recovery and purification, regulatory requirements, and emissions must be managed successfully. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of cellulose derivatives obtained from bacterial cellulose

International Nuclear Information System (INIS)

Oliveira, Rafael L. de; Barud, Hernane; Ribeiro, Sidney J.L.; Messaddeq, Younes

2011-01-01

The chemical modification of cellulose leads to production of derivatives with different properties from those observed for the original cellulose, for example, increased solubility in more traditional solvents. In this work we synthesized four derivatives of cellulose: microcrystalline cellulose, cellulose acetate, methylcellulose and carboxymethylcellulose using bacterial cellulose as a source. These were characterized in terms of chemical and structural changes by examining the degree of substitution (DS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy - NMR 13 C. The molecular weight and degree of polymerization were evaluated by viscometry. The characterization of the morphology of materials and thermal properties were performed with the techniques of X-ray diffraction, electron microscopy images, differential scanning calorimetry (DSC) and thermogravimetric analysis. (author)

Recyclable colorimetric sensor of Cr3 + and Pb2 + ions simultaneously using a zwitterionic amino acid modified gold nanoparticles

Science.gov (United States)

Sang, Fuming; Li, Xin; Zhang, Zhizhou; Liu, Jia; Chen, Guofu

2018-03-01

In this work, a rapid, simple and sensitive colorimetric sensor for simultaneous (or respective) detection of Cr3 + and Pb2 + using tyrosine functionalized gold nanoparticles (AuNPsTyr) has been developed. Tyrosine, a natural and zwitterionic amino acid, could be as a reducing and capping agent to synthesise AuNPs and allow for the simultaneous and selective detection of Cr3 + and Pb2 +. Upon the addition of Cr3 + or Pb2 + (a combination of them), the color of AuNPsTyr solution changes from red to blue grey and the characteristic surface plasmon resonance (SPR) band is red-shifted to 580 nm due to the aggregation of AuNPs. Interestingly, the aggregated AuNPsTyr can be regnerated and recycled by removing Pb2 + and Cr3 +. Even after 3 rounds, AuNPsTyr show almost the same A580 nm / A520 nm value for the assays of Pb2 + and Cr3 +, indicating the good recyclability of the colorimetric sensor. The responding time (within 1 min) and sensitivity of the colorimetric sensor are largely improved after the addition of 0.1 M NaCl. Moreover, the AuNPsTyr aggregated by Cr3 + or Pb2 + (a combination of them) show excellent selectivity compared to other metal ions (Cr3 +, Pb2 +, Fe2 +,Cu2 +,Zn2 +,Cr6 +,Ni2 +,Co2 +,Hg2 +,Mn2 +,Mg2 +,Ca2 +,Cd2 +). More importantly, the developed sensor manifests good stability at room temperature for 3 months, which has been successfully used to determine Cr3 + and Pb2 + in the real water samples with a high sensitivity.

Constrained dansyl derivatives reveal bacterial specificity of highly conserved thymidylate synthases.

Science.gov (United States)

Calò, Sanuele; Tondi, Donatella; Ferrari, Stefania; Venturelli, Alberto; Ghelli, Stefano; Costi, Maria Paola

2008-03-25

The elucidation of the structural/functional specificities of highly conserved enzymes remains a challenging area of investigation, and enzymes involved in cellular replication are important targets for functional studies and drug discovery. Thymidylate synthase (TS, ThyA) governs the synthesis of thymidylate for use in DNA synthesis. The present study focused on Lactobacillus casei TS (LcTS) and Escherichia coli TS (EcTS), which exhibit 50 % sequence identity and strong folding similarity. We have successfully designed and validated a chemical model in which linear, but not constrained, dansyl derivatives specifically complement the LcTS active site. Conversely, chemically constrained dansyl derivatives showed up to 1000-fold improved affinity for EcTS relative to the inhibitory activity of linear derivatives. This study demonstrates that the accurate design of small ligands can uncover functional features of highly conserved enzymes.

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.

Enhanced Electromagnetic and Chemical/Biological Sensing. Properties of Atomic Cluster-Derived Materials

National Research Council Canada - National Science Library

Schatz, George

2003-01-01

The Center for Atomic Clusters-derived Materials performed a broad range of research concerned with synthesizing, characterizing and utilizing atomic and molecular clusters, nanoparticles and nanomaterial...

The role of cellular and molecular studies in evaluation of health effects from combined radiation and chemical exposures

International Nuclear Information System (INIS)

Brooks, A.L.; Gilbert, E.S.; Kitchin, R.M.; Johnson, N.F.

1992-06-01

Additive models are currently used to predict risks following exposure to multiple agents or complex mixtures. Use of these models is questioned because different methods are used to derive risks for chemical and physical agents depending on the database used. Risks for the induction of cancer from radiation are based on large sets of human data, while standards are set for most chemical carcinogens using information derived from animal studies. However, it is not, from a scientific point of view, appropriate to add risks from physical and chemical agents to derive potential health impact from combined exposures. The range of safety factors built into the estimates, the large differences in the data sets used to evaluate and establish standards, and the differences in the basic philosophy for deriving risks for physical and chemical agents make the additive model unacceptable for estimating risks from combined exposures. To understand the potential health impacts from environmental exposure, it is important (1) to consider how risks were derived and (2) to determine if interactions exist between damage induced by the different agents to ensure that additive assumptions are valid. This presentation discusses a number of these safety factors for specific chemicals

Derivation of the Second Law of Thermodynamics from Boltzmann's Distribution Law.

Science.gov (United States)

Nelson, P. G.

1988-01-01

Shows how the thermodynamic condition for equilibrium in an isolated system can be derived by the application of Boltzmann's law to a simple physical system. States that this derivation could be included in an introductory course on chemical equilibrium to help prepare students for a statistical mechanical treatment presented in the curriculum.…

Ab initio and density functional force field studies on the IR spectra and structure of diazonium dicyanomethylide (diazodicyanomethane)

Science.gov (United States)

Georgieva, Miglena K.

2004-03-01

The structure of diazonium dicyanomethylide (diazodicyanomethane) +N 2-C(CN) 2-↔N 2C(CN) 2 has been studied on the basis of ab initio HF, MP2 and DFT BLYP force field calculations, as well as of literature IR spectra and X-ray diffraction structural data. The results have been compared with those obtained for a series of chemical relatives of the title compound, i.e. molecules, push-pull molecules, anions and zwitterions, containing α-dicyano or diazo fragments, and especially substituted ammonium dicyanomethylides and diazomethane +N 2-CH 2-↔N 2CH 2. It has been found on the basis of spectral, bond length, bond order and electric charge analyses that the diazonium (or carbanionic, left) canonical form is much more important for the title zwitterion, than the corresponding one for diazomethane. So, the title compound can be named (and considered as) both diazonium dicyanomethylide and dicyanodiazomethane.

Dielectric and vibrational properties of amino acids

Science.gov (United States)

Tulip, P. R.; Clark, S. J.

2004-09-01

We calculate polarizability tensors and normal mode frequencies for the amino acids alanine, leucine, isoleucine, and valine using density functional perturbation theory implemented within the plane wave pseudopotential framework. It is found that the behavior of the electron density under external fields depends to a large extent on the geometrical structure of the molecule in question, rather than simply on the constituent functional groups. The normal modes are able to help distinguish between the different types of intramolecular hydrogen bonding present, and help to explain why leucine is found in the zwitterionic form for the gaseous phase. Calculated IR spectra show a marked difference between those obtained for zwitterionic and nonzwitterionic molecules. These differences can be attributed to the different chemical and hydrogen bonds present. Effective dynamical charges are calculated, and compared to atomic charges obtained from Mulliken population analysis. It is found that disagreement exists, largely due to the differing origins of these quantities.

Computational Approaches to Chemical Hazard Assessment

Science.gov (United States)

Luechtefeld, Thomas; Hartung, Thomas

2018-01-01

Summary Computational prediction of toxicity has reached new heights as a result of decades of growth in the magnitude and diversity of biological data. Public packages for statistics and machine learning make model creation faster. New theory in machine learning and cheminformatics enables integration of chemical structure, toxicogenomics, simulated and physical data in the prediction of chemical health hazards, and other toxicological information. Our earlier publications have characterized a toxicological dataset of unprecedented scale resulting from the European REACH legislation (Registration Evaluation Authorisation and Restriction of Chemicals). These publications dove into potential use cases for regulatory data and some models for exploiting this data. This article analyzes the options for the identification and categorization of chemicals, moves on to the derivation of descriptive features for chemicals, discusses different kinds of targets modeled in computational toxicology, and ends with a high-level perspective of the algorithms used to create computational toxicology models. PMID:29101769

Liquid chromatography tandem mass spectrometry determination of chemical markers and principal component analysis of Vitex agnus-castus L. fruits (Verbenaceae) and derived food supplements.

Science.gov (United States)

Mari, Angela; Montoro, Paola; Pizza, Cosimo; Piacente, Sonia

2012-11-01

A validated analytical method for the quantitative determination of seven chemical markers occurring in a hydroalcoholic extract of Vitex agnus-castus fruits by liquid chromatography electrospray triple quadrupole tandem mass spectrometry (LC/ESI/(QqQ)MSMS) is reported. To carry out a comparative study, five commercial food supplements corresponding to hydroalcoholic extracts of V. agnus-castus fruits were analysed under the same chromatographic conditions of the crude extract. Principal component analysis (PCA), based only on the variation of the amount of the seven chemical markers, was applied in order to find similarities between the hydroalcoholic extract and the food supplements. A second PCA analysis was carried out considering the whole spectroscopic data deriving from liquid chromatography electrospray linear ion trap mass spectrometry (LC/ESI/(LIT)MS) analysis. High similarity between the two PCA was observed, showing the possibility to select one of these two approaches for future applications in the field of comparative analysis of food supplements and quality control procedures. Copyright © 2012 Elsevier B.V. All rights reserved.

Decomposition theory of chemical reactions

International Nuclear Information System (INIS)

Rabitz, S.; Rabitz, H.

1977-01-01

The coupled channel formulation is utilized to variationally derive approximate closed-form expressions for reactive transition matrices. In conjunction with this effort it is shown that the effect of differing choices of possible channel coupling arrays becomes important when incomplete channel basis sets are used. Generalized techniques are employed to derive the necessary variational principles. The inherent coupling of the Green's functions in the resulting expression for the transition matrix makes inclusion of continuum states in the basis sets less crucial. The practical viability of this formulation as a computational scheme for chemical systems is discussed

Unusual metal coordination chemistry from an amino-amide derivative of 4-nitrophenol, a surprising ligand

DEFF Research Database (Denmark)

McGinley, John; McKee, Vickie; Toftlund, Hans

2009-01-01

The simple ligand N-(2-aminoethyl)-2-hydroxy-5-nitrobenzamide () exhibits several coordination modes depending on the reaction conditions, acting as a zwitterion on its own or being ionic in the presence of acid and depending on the concentration of metal present in a reaction, it can coordinate...... to the metal in either a 1:1 or a 1:2 metal:ligand mode. Furthermore, the role of solvent plays an important role in these complexation reactions with both four and six coordinate copper complexes being obtained using water as solvent but only six coordinate copper complexes obtained using acetonitrile...

ACTION OF CHEMICALLY DIFFERENT PROSTAGLANDIN BLOCKERS ON THE ADRENAL HORMONES IN PIGEONS DURING STRESS.

Science.gov (United States)

Sarkar, S; Ghosh, S; Sengupta, S; Dasadhikari, S; Ghosh, A

1999-01-01

The effect of prostaglandin (PG) inhibitors differing in their chemical nature, viz. Aspirin (acetylsalicylic acid), Mefenamic acid (fenamates), Diclofenac (phenylacetic acid derivative) and Piroxicam (oxicam derivative) on the adrenal hormones was studied in acutely stressed pigeons. None of these PG blockers exerted any significant effect on the catecholamine and corticosterone content of the control, i.e. unstressed pigeon adrenal gland excepting mefenamic acid which caused a release of epinephrine. Aspirin, diclofenac and piroxicam did not modulate the catecholamine or corticosterone secretion whereas mefenamic acid caused a released of both epinephrine and norepinephrine and increased the adrenal corticosterone content in the acutely stressed pigeons. These results were compared with those obtained from studies on the effects of other chemically different PG blockers, indomethacin (a methylated indole derivative) and ibuprofen (a propionic acid derivative). It is suggested that chemically and structurally different PG inhibitors show diverse action in the same species under similar stress conditions.

Chemical Synthesis and Biological Activities of Novel Pleuromutilin Derivatives with Substituted Amino Moiety

Science.gov (United States)

Shang, Ruofeng; Wang, Shengyu; Xu, Ximing; Yi, Yunpeng; Guo, Wenzhu; YuLiu; Liang, Jianping

2013-01-01

Novel pleuromutilin derivatives designed based on the structure of valnemulin were synthesized and evaluated for their in vitro antibacterial activities. These pleuromutilin derivatives with substituted amino moiety exhibited excellent activities against methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, Escherichia coli, and Streptococcus agalactiae. Compound 5b showed the highest antibacterial activities and even exceeded tiamulin. Moreover, the docking experiments provided information about the binding model between the synthesized compounds and peptidyl transferase center (PTC) of 23S rRNA. PMID:24376551

Chemical synthesis and biological activities of novel pleuromutilin derivatives with substituted amino moiety.

Directory of Open Access Journals (Sweden)

Ruofeng Shang

Full Text Available Novel pleuromutilin derivatives designed based on the structure of valnemulin were synthesized and evaluated for their in vitro antibacterial activities. These pleuromutilin derivatives with substituted amino moiety exhibited excellent activities against methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, Escherichia coli, and Streptococcus agalactiae. Compound 5b showed the highest antibacterial activities and even exceeded tiamulin. Moreover, the docking experiments provided information about the binding model between the synthesized compounds and peptidyl transferase center (PTC of 23S rRNA.

Theoretical predictions of anti-corrosive properties of THAM and its derivatives.

Science.gov (United States)

Malinowski, Szymon; Jaroszyńska-Wolińska, Justyna; Herbert, Tony

2017-12-04

We present quantum chemical theoretical estimations of the anti-corrosive properties of THAM (tris(hydroxymethyl)aminomethane) and three derivatives that differ in the number of benzene rings: THAM-1 (2-amino-3-hydroxy-2-(hydroxymethyl) propylobenzoate), THAM-2 (2-amino-2-(hydroxymetyl)prapan-1,3-diyldibenzoate) and THAM-3 (2-amino-propan-1,2,3-triyltribenzoate). Fourteen exchange-correlation functionals based on the density functional theory (DFT) were chosen for quantum chemical study of THAM derivatives. The objective was to examine the effect of benzene rings on potential anti-corrosive properties of THAM compounds. The results indicate that the addition of benzene rings in THAM derivatives is likely to significantly enhance electrostatic bonding of a THAM-based coating to a presented metal surface and, thus, its adhesion and long-term effect in corrosion inhibition. Whereas it is clear that all three derivatives appear to be superior in their bonding characteristics to pure THAM, the potential order of merit between the three is less clear, although THAM-3 presents as possibly superior.

Contact allergy to isoeugenol and its derivatives

DEFF Research Database (Denmark)

Tanaka, Susumu; Royds, C; Buckley, Christopher D

2004-01-01

A total of 2261 (808 male, 1453 female) consecutive patients attending contact dermatitis clinics were patch tested to isoeugenol and its derivatives listed in the EU Inventory of Fragrance Ingredients. Positive reactions were found to isoeugenol in 40, transisoeugenol in 40, isoeugenyl acetate...... and 15/16 of those to isoeugenyl phenylacetate but in none of those 6 positive to isoeugenyl methyl ether and in neither of those 2 positive to benzyl isoeugenyl ether. Concomitant contact allergy between isoeugenol and its derivatives may occur through chemical cross-reactivity or local skin metabolism...... of the derivatives. It is more commonly observed with the esters rather than the ethers. Isoeugenyl acetate has been proposed as an alternative to isoeugenol, but there is a high degree of concomitant reactivity with isoeugenol....

Synthetic Approaches and Biological Activities of 4-Hydroxycoumarin Derivatives

Directory of Open Access Journals (Sweden)

Oee-Sook Park

2009-11-01

Full Text Available The main purpose of this review is to summarize recent chemical syntheses and structural modifications of 4-hydroxycoumarin and its derivatives, of interest due to their characteristic conjugated molecular architecture and biological activities.

Partial chemical equilibrium in fluid dynamics

International Nuclear Information System (INIS)

Ramshaw, J.D.

1980-01-01

An analysis is given for the flow of a multicomponent fluid in which an arbitrary number of chemical reactions may occur, some of which are in equilibrium while the others proceed kinetically. The primitive equations describing this situation are inconvenient to use because the progress rates omega-dot/sub s/ for the equilibrium reactions are determined implicitly by the associated equilibrium constraint conditions. Two alternative equivalent equation systems that are more pleasant to deal with are derived. In the first system, the omega-dot/sub s/ are eliminated by replacing the transport equations for the chemical species involved in the equilibrium reactions with transport equations for the basic components of which these species are composed. The second system retains the usual species transport equations, but eliminates the nonlinear algebraic equilibrium constraint conditions by deriving an explicit expression for the omega-dot/sub s/. Both systems are specialized to the case of an ideal gas mixture. Considerations involved in solving these equation systems numerically are discussed briefly

Brevianamides and Mycophenolic Acid Derivatives from the Deep-Sea-Derived Fungus Penicillium brevicompactum DFFSCS025

Directory of Open Access Journals (Sweden)

Xinya Xu

2017-02-01

Full Text Available Four new compounds (1–4, including two brevianamides and two mycochromenic acid derivatives along with six known compounds were isolated from the deep-sea-derived fungus Penicillium brevicompactum DFFSCS025. Their structures were elucidated by spectroscopic analysis. Moreover, the absolute configurations of 1 and 2 were determined by quantum chemical calculations of the electronic circular dichroism (ECD spectra. Compound 9 showed moderate cytotoxicity against human colon cancer HCT116 cell line with IC50 value of 15.6 μM. In addition, 3 and 5 had significant antifouling activity against Bugula neritina larval settlement with EC50 values of 13.7 and 22.6 μM, respectively. The NMR data of 6, 8, and 9 were assigned for the first time.

Improved chemical identification from sensor arrays using intelligent algorithms

Science.gov (United States)

Roppel, Thaddeus A.; Wilson, Denise M.

2001-02-01

Intelligent signal processing algorithms are shown to improve identification rates significantly in chemical sensor arrays. This paper focuses on the use of independently derived sensor status information to modify the processing of sensor array data by using a fast, easily-implemented "best-match" approach to filling in missing sensor data. Most fault conditions of interest (e.g., stuck high, stuck low, sudden jumps, excess noise, etc.) can be detected relatively simply by adjunct data processing, or by on-board circuitry. The objective then is to devise, implement, and test methods for using this information to improve the identification rates in the presence of faulted sensors. In one typical example studied, utilizing separately derived, a-priori knowledge about the health of the sensors in the array improved the chemical identification rate by an artificial neural network from below 10 percent correct to over 99 percent correct. While this study focuses experimentally on chemical sensor arrays, the results are readily extensible to other types of sensor platforms.

Treatment of biomass to obtain a target chemical

Science.gov (United States)

Dunson, Jr., James B.; Tucker, III, Melvin P.; Elander, Richard T.; Hennessey, Susan Marie

2010-08-24

Target chemicals were produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

Synthesis of inulin derivatives with quaternary phosphonium salts and their antifungal activity.

Science.gov (United States)

Chen, Yuan; Tan, Wenqiang; Li, Qing; Dong, Fang; Gu, Guodong; Guo, Zhanyong

2018-03-13

Inulin is a kind of renewable and biodegradable carbohydrate with good water solubility and numerous physiological functions. For further utilization of inulin, chemical modification can be applied to improve its bioactivities. In this paper, five novel inulin derivatives were synthesized via chemical modification with quaternary phosphonium salt. Their antifungal activity against three kinds of plant pathogens including Colletotrichum lagenarium, Phomopsis asparagi, and Fusarium oxysporum was assessed with radial growth assay in vitro. Results revealed that all the inulin derivatives exhibited improved antifungal activity compared with inulin. Particularly, inulin modified with triphenylphosphine (TPhPAIL) exhibited the best antifungal activity with inhibitory indices of 80.0%, 78.8%, and 87.4% against Colletotrichum lagenarium, Phomopsis asparagi, and Fusarium oxysporum at 1.0mg/mL respectively. The results clearly showed that chemical modification of inulin with quaternary phosphonium salt could efficiently improve derivatives' antifungal activity. Further analysis of results indicated that the antifungal activity was influenced by alkyl chain length or electron-withdrawing ability of the grafted quaternary phosphonium salts. Longer alkyl chain lengths or the stronger electron-withdrawing groups would lead to enhanced antifungal efficacy. Copyright © 2018 Elsevier B.V. All rights reserved.

Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of 13C chemical shifts

Directory of Open Access Journals (Sweden)

Simone Di Micco

2013-12-01

Full Text Available In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of 13C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of 13C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides.

Antidiabetic plant-derived nutraceuticals: a critical review.

Science.gov (United States)

Naveen, Jayapal; Baskaran, Vallikannan

2018-06-01

Diabetes mellitus (DM) is one of the major health problems in the world, especially amongst the urban population. Chemically synthesized drugs used to decrease the ill effects of DM and its secondary complications cause adverse side effects, viz., weight gain, gastrointestinal disturbances, and heart failure. Currently, various other approaches, viz., diet control, physical exercise and use of antidiabetic plant-derived molecules/foods are advocated to manage DM, as they are economical with fewer or no side effects. This review mainly focuses on antidiabetic plants, chemically characterized plant molecules and plant-based foods in the treatment of DM. Very little science-based evidence is available on the mechanism of action of plant-derived food molecules on the DM targets. Critical DM targets include α-amylase, α-glucosidase, DPP-IV, aldose reductase, PPAR-γ, AMP kinase and GLUT4. In-depth studies carried out on a few of those targets with specific mechanisms of action are addressed in this review. This review may help future researchers in identifying a right plant molecule to treat DM or to develop food formulations for DM management.

Electrochemical energy storage devices comprising self-compensating polymers

Science.gov (United States)

Johnson, Paul; Bautista-Martinez, Jose Antonio; Friesen, Cody; Switzer, Elise

2018-01-30

The disclosed technology relates generally to devices comprising conductive polymers and more particularly to electrochemical devices comprising self-compensating conductive polymers. In one aspect, electrochemical energy storage device comprises a negative electrode comprising an active material including a redox-active polymer. The device additionally comprises a positive electrode comprising an active material including a redox-active polymer. The device further comprises an electrolyte material interposed between the negative electrode and positive electrode and configured to conduct mobile counterions therethrough between the negative electrode and positive electrode. At least one of the negative electrode redox-active polymer and the positive electrode redox-active polymer comprises a zwitterionic polymer unit configured to reversibly switch between a zwitterionic state in which the zwitterionic polymer unit has first and second charge centers having opposite charge states that compensate each other, and a non-zwitterionic state in which the zwitterionic polymer unit has one of the first and second charge centers whose charge state is compensated by mobile counterions.

Improved anti-inflammatory activity of three new terpenoids derived, by systematic chemical modifications, from the abundant triterpenes of the flowery plant Calendula officinalis.

Science.gov (United States)

Neukirch, Hannes; D'Ambrosio, Michele; Sosa, Silvio; Altinier, Gianmario; Della Loggia, Roberto; Guerriero, Antonio

2005-05-01

Rings A, D and E of faradiol (1), and ring E of both arnidiol (10) and calenduladiol (4) have been subjected to various selective chemical manipulations to modify polarity, water affinity, H-bonding, sterics, and number of aromatic groups of these anti-inflammatory natural compounds. A total of 15 new and four known pentacyclic triterpenoids have been obtained in this way. Some 13 terpenoids were evaluated for their topical anti-inflammatory activities with respect to inhibition of croton oil induced ear oedema in mouse. Three derivatives of 1, the C(16) benzyl ether 15, the C(30) aldehyde 24, and the C(30) primary alcohol 25 showed significantly improved anti-inflammatory potencies, which is relevant for (future) structure-activity-relationship (SAR) studies.

M-Polynomials and Topological Indices of Dominating David Derived Networks

Directory of Open Access Journals (Sweden)

Kang Shin Min

2018-03-01

Full Text Available There is a strong relationship between the chemical characteristics of chemical compounds and their molecular structures. Topological indices are numerical values associated with the chemical molecular graphs that help to understand the physical features, chemical reactivity, and biological activity of chemical compound. Thus, the study of the topological indices is important. M-polynomial helps to recover many degree-based topological indices for example Zagreb indices, Randic index, symmetric division idex, inverse sum index etc. In this article we compute M-polynomials of dominating David derived networks of the first type, second type and third type of dimension n and find some topological properties by using these M-polynomials. The results are plotted using Maple to see the dependence of topological indices on the involved parameters.

Yield of Peas Treated with Compost and Chemical Fertilizer Using 15N Technique

International Nuclear Information System (INIS)

El-Degwy, S.M.A.

2011-01-01

A field experiment was carried out to evaluate the yield of peas treated with organic compost and mineral N fertilizer under sandy soil conditions. The obtained results showed that all the tested vegetative growth parameters, i.e. fresh and dry weight of leaves, root and pods of pea plants, were significantly increased with increasing the levels of mineral N fertilizer from 20 up to 50 kg N ha-1 either solely or in combination with compost. Nitrogen, phosphorus and potassium uptake by pea plants were ranked as follow: chemical N fertilize > compost + chemical N fertilize > compost. Organic additives either alone or in combination with chemical fertilizer had enhanced Ndff uptake by pods over aerial parts and roots while reversible trend was noticed with sole application of chemical fertilizer. Nitrogen derived from compost (Ndfc) and uptake by aerial parts followed by pods were enhanced by addition of organic plus chemical fertilizers comparable to sole addition of organic compost. In other term, chemical fertilizer had enhanced the portion of N derived from organic compost

catena-Poly[[bis(nitrato-κ2O,O′barium]-bis(μ-l-histidine-κ3O,O′:O

Directory of Open Access Journals (Sweden)

P. Arularasan

2013-11-01

Full Text Available In the polymeric title compound, [Ba(NO32(C6H9N3O22]n, the BaII atom is located on a crystallographic twofold axis and is coordinated by ten O atoms. Six are derived from two zwitterionic l-histidine molecules that simultaneously chelate one BaII atom and bridge to another. The remaining four O atoms are derived from two chelating nitrates. The molecules assemble to form a chain along [010]. In the crystal, chains are linked via N—H...O and N—H...N hydrogen bonds, generating a three-dimensional network.

2-(1-Amino-4-tert-butylcyclohexylacetic acid (tBu-β3,3-Ac6c hemihydrateIIIM communication number IIIM/1552/2013.

Directory of Open Access Journals (Sweden)

Naiem Ahmad Wani

2013-06-01

Full Text Available The title compound, C12H23NO2·0.5H2O, crystallized with two 2-(1-amino-4-tert-butylcyclohexylacetic acid molecules, which are present as zwitterions, and one water molecule in the asymmetric unit. The molecular structure of each zwitterion is stabilized by an intramolecular six-membered (C6 N—H...O hydrogen bond. In the crystal, the two independent zwitterions are linked head-to-head by N—H...O hydrogen bonds. Further O—H...O and N—H...O hydrogen bonds link the zwitterions and the water molecules, forming sandwich-like layers, with a hydrophilic filling and a hydrophobic exterior, lying parallel to the ab plane.

Vapor pressures and sublimation enthalpies of novel bicyclic heterocycle derivatives

International Nuclear Information System (INIS)

Blokhina, Svetlana V.; Ol’khovich, Marina V.; Sharapova, Angelica V.; Perlovich, German L.; Proshin, Alexey N.

2014-01-01

Highlights: • The vapor pressures of novel bicyclo-derivatives of amine were measured. • Thermodynamic functions of sublimation were calculated. • The influence of substituent structure and chemical nature on the vapor pressure was studied. -- Abstract: The vapor pressures of five novel bicyclic heterocycle derivatives were measured over the temperature 341.15 to 396.15 K using the transpiration method by means of an inert gas carrier. From these results the standard enthalpies and Gibbs free energies of sublimation at the temperature 298.15 K were calculated. The effects of alkyl- and chloro-substitutions on changes in the thermodynamic functions have been investigated. Quantitative structure–property relationship on the basis HYBOT physico-chemical descriptors for biologically active compounds have been developed to predict the sublimation enthalpies and Gibbs free energies of the compounds studied

Molecular dynamics of a proguanil derivative | Muhammad | Bayero ...

African Journals Online (AJOL)

... ab-initio Quantum chemical calculations at the Restricted Hatree-Fock (RHF) ... and 6-31++G basis sets were carried out for inclusion of electron correlation. ... The dipole moment of the Proguanil's derivative at both levels of theory is ... Keywords: Proguanil, Density Functional Theory, Restricted Hartree Fock, Gaussian ...

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities

Directory of Open Access Journals (Sweden)

Mireille Fouillaud

2016-03-01

Full Text Available Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi′s productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities.

Science.gov (United States)

Fouillaud, Mireille; Venkatachalam, Mekala; Girard-Valenciennes, Emmanuelle; Caro, Yanis; Dufossé, Laurent

2016-03-25

Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s) due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi's productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.

Partition coefficients of some purine derivatives and its application to pharmacokinetics.

Science.gov (United States)

Chrzanowska, M; Sobiak, J; Kuehn, M; Dorawa, E; Hermann, T

2009-12-01

Metazathioprine (MAZA), a methylated derivative of azathioprine (AZA), demonstrated the greatest values of apparent and specific partition coefficients in n-octanol/phosphate buffer at pH 5.7 and pH 7.4 among purine derivatives such as 6-mercaptopurine (6-MP), 6-thioguanine (6-TG) and AZA. Introduction of a methyl group into the imidazole ring of AZA increases lipophilic properties of MAZA compared to AZA. Mass balance of purine derivatives in n-octanol and in phosphate buffer indicated their chemical stability in those media.

Chemical tailoring of teicoplanin with site-selective reactions.

Science.gov (United States)

Pathak, Tejas P; Miller, Scott J

2013-06-05

Semisynthesis of natural product derivatives combines the power of fermentation with orthogonal chemical reactions. Yet, chemical modification of complex structures represents an unmet challenge, as poor selectivity often undermines efficiency. The complex antibiotic teicoplanin eradicates bacterial infections. However, as resistance emerges, the demand for improved analogues grows. We have discovered chemical reactions that achieve site-selective alteration of teicoplanin. Utilizing peptide-based additives that alter reaction selectivities, certain bromo-teicoplanins are accessible. These new compounds are also scaffolds for selective cross-coupling reactions, enabling further molecular diversification. These studies enable two-step access to glycopeptide analogues not available through either biosynthesis or rapid total chemical synthesis alone. The new compounds exhibit a spectrum of activities, revealing that selective chemical alteration of teicoplanin may lead to analogues with attenuated or enhanced antibacterial properties, in particular against vancomycin- and teicoplanin-resistant strains.

A New Topology of Solutions of Chemical Equations

International Nuclear Information System (INIS)

Risteski, Ice B.

2013-01-01

In this work is induced a new topology of solutions of chemical equations by virtue of point-set topology in an abstract stoichiometrical space. Subgenerators of this topology are the coefficients of chemical reaction. Complex chemical reactions, as those of direct reduction of hematite with a carbon, often exhibit distinct properties which can be interpreted as higher level mathematical structures. Here we used a mathematical model that exploits the stoichiometric structure, which can be seen as a topology too, to derive an algebraic picture of chemical equations. This abstract expression suggests exploring the chemical meaning of topological concept. Topological models at different levels of realism can be used to generate a large number of reaction modifications, with a particular aim to determine their general properties. The more abstract the theory is, the stronger the cognitive power is

Application of cinchona-sulfonate-based chiral zwitterionic ion exchangers for the separation of proline-containing dipeptide rotamers and determination of on-column isomerization parameters from dynamic elution profiles.

Science.gov (United States)

Wernisch, Stefanie; Trapp, Oliver; Lindner, Wolfgang

2013-09-17

The interconversion of cis and trans isomers of dipeptides containing C-terminal proline was studied by dynamic chromatography on zwitterionic chiral stationary phases at temperatures ranging from -15°C to +45°C The cis-trans isomers could be separated below 0°C and above 0-10°C plateau formation and peak coalescence phenomena occurred, which is characteristic for a dynamic process at the time-scale of partitioning. At and above room temperature, full coalescence was observed, which allowed separations of enantiomers without interference from interconversion effects. Analysis of the dynamic elution profiles of the interconverting peptides allowed the determination of isomerization rate constants and thermodynamic activation parameters (isomerization enthalpy, entropy and activation energy). In accordance with established results, isomerization rates and thermodynamic parameters were found to depend on the nature of the N-terminal amino acid. Isomerization barriers were only slightly lower than values determined with other methods but significant differences in the relative contributions of the activation enthalpy and entropy as well as isomerization rates pointed toward selector-moderated isomerization dynamics. Copyright © 2013 Elsevier B.V. All rights reserved.

Chemically Modified Starch; Allyl- and Epoxy-Starch Derivatives: Their Synthesis and Characterization

NARCIS (Netherlands)

Franssen, M.C.R.; Boeriu, C.

2014-01-01

Both native and modified starches, such as starch that is pregelatinized, extruded, acid-converted, cross-linked, and substituted, are widely used in industry. This chapter describes a mild two-step process for the synthesis of novel, highly reactive granular epoxy-starch derivatives. Via this

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 124; Issue 3. Activated anilide in heterocyclic synthesis: Synthesis of new hydrazo, dihydropyridazine, tetrahydropyridine, dihydropyridine and pyranopyridine derivatives. Ibrahim Saad Abdel Hafiz Mahmoud Mohamed Mahfouz Ramiz Mohamed Ahmed Elian. Volume ...

New derivatives of alkaloids peganine, vazicinone and garmine

International Nuclear Information System (INIS)

Agedilova, M.T.; Turmukhambetov, A.Zh.; Kazantsev, A.V.; Shul'ts, E.E.

2005-01-01

It was studied the chemical modification of chinazolin alkaloids peganine and vasicinone and indolin alkaloid garmine. The corresponding halogen-, alkyl-, cetyl and hydrazone derivatives and its salts were obtained. The structure of synthesized compounds was definite by following spectral methods: IR, UV, 1 H, 13 C and 11 B NMR spectroscopy

Systemic fungicidal activity of 1,4-oxathiin derivatives.

Science.gov (United States)

Schmeling, B V; Kulka, M

1966-04-29

Treatment of pinto bean and barley seed with 1,4-oxathiin derivatives gave disease control by systemic fungicidal action of such pathogenic fungi as Uromyces phaseoli and Ustilago nuda. The two chemicals, D735 and F461, were highly specific and selective against the pathogens without injury of the hosts.

Chemical products and industrial materials

International Nuclear Information System (INIS)

1995-12-01

A compilation of all universities, industrial and governmental agencies in Quebec which are actively involved in research and development of chemical products and industrial materials derived from biomass products, was presented. Each entry presented in a standard format that included a description of the major research activities of the university or agency, the principal technologies used in the research, available research and analytical equipment, a description of the research personnel, names, and addresses of contact persons for the agency or university. Thirty entries were presented. These covered a wide diversity of activities including biotechnological research such as genetic manipulations, bioconversion, fermentation, enzymatic hydrolysis and physico-chemical applications such as bleaching, de-inking, purification and synthesis. tabs

Adult Human Stem Cell-Derived Cardiomyocytes: An Alternative Model for Evaluating Chemical and Environmental Pollutant Cardiotoxicity

Science.gov (United States)

Heart disease is increasing globally with a significant percentage of the increase being attributed to chemical and pollution exposures. Currently, no alternative or in vitro testing models exist to rapidly and accurately determine the cardiac effects of chemicals and/or pollutan...

Ionic Conductivity of Polyelectrolyte Hydrogels.

Science.gov (United States)

Lee, Chen-Jung; Wu, Haiyan; Hu, Yang; Young, Megan; Wang, Huifeng; Lynch, Dylan; Xu, Fujian; Cong, Hongbo; Cheng, Gang

2018-02-14

Polyelectrolytes have many important functions in both living organisms and man-made applications. One key property of polyelectrolytes is the ionic conductivity due to their porous networks that allow the transport of water and small molecular solutes. Among polyelectrolytes, zwitterionic polymers have attracted huge attention for applications that involve ion transport in a polyelectrolyte matrix; however, it is still unclear how the functional groups of zwitterionic polymer side chains affect their ion transport and swelling properties. In this study, zwitterionic poly(carboxybetaine acrylamide), poly(2-methacryloyloxyethyl phosphorylcholine), and poly(sulfobetaine methacrylate) hydrogels were synthesized and their ionic conductivity was studied and compared to cationic, anionic, and nonionic hydrogels. The change of the ionic conductivity of zwitterionic and nonionic hydrogels in different saline solutions was investigated in detail. Zwitterionic hydrogels showed much higher ionic conductivity than that of the widely used nonionic poly(ethylene glycol) methyl ether methacrylate hydrogel in all tested solutions. For both cationic and anionic hydrogels, the presence of mobile counterions led to high ionic conductivity in low salt solutions; however, the ionic conductivity of zwitterionic hydrogels surpassed that of cationic and ionic hydrogels in high salt solutions. Cationic and anionic hydrogels showed much higher water content than that of zwitterionic hydrogels in deionized water; however, the cationic hydrogels shrank significantly with increasing saline concentration. This work provides insight into the effects of polyelectrolyte side chains on ion transport. This can guide us in choosing better polyelectrolytes for a broad spectrum of applications, including bioelectronics, neural implants, battery, and so on.

Free radicals in chemical carcinogenesis.

Science.gov (United States)

Clemens, M R

1991-12-15

During the past decade, remarkable progress has been made in our understanding of cancer-causing agents, mechanisms of cancer formation and the behavior of cancer cells. Cancer is characterized primarily by an increase in the number of abnormal cells derived from a given normal tissue, invasion of adjacent tissues by these abnormal cells, and lymphatic or blood-borne spread of malignant cells to regional lymph nodes and to distant sites (metastasis). It has been estimated that about 75-80% of all human cancers are environmentally induced, 30-40% of them by diet. Only a small minority, possibly no more than 2% of all cases, result purely from inherent genetic changes. Several lines of evidence confirm that the fundamental molecular event or events that cause a cell to become malignant occur at the level of the DNA and a variety of studies indicate that the critical molecular event in chemical carcinogenesis is the interaction of the chemical agent with DNA. The demonstration that DNA isolated from tumor cells can transfect normal cells and render them neoplastic provides direct proof that an alteration of the DNA is responsible for cancer. The transforming genes, or oncogenes, have been identified by restriction endonuclease mapping. One of the characteristics of tumor cells generated by transformation with viruses, chemicals, or radiation is their reduced requirement for serum growth factors. A critical significance of electrophilic metabolites of carcinogenes in chemical carcinogenesis has been demonstrated. A number of "proximate" and "ultimate" metabolites, especially those of aromatic amines, were described. The "ultimate" forms of carcinogens actually interact with cellular constituents to cause neoplastic transformation and are the final metabolic products in most pathways. Recent evidence indicates that free radical derivatives of chemical carcinogens may be produced both metabolically and nonenzymatically during their metabolism. Free radicals carry no

Discovery of novel selenium derivatives as Pin1 inhibitors by high-throughput screening

International Nuclear Information System (INIS)

Subedi, Amit; Shimizu, Takeshi; Ryo, Akihide; Sanada, Emiko; Watanabe, Nobumoto; Osada, Hiroyuki

2016-01-01

Peptidyl prolyl cis/trans isomerization by Pin1 regulates various oncogenic signals during cancer progression, and its inhibition through multiple approaches has established Pin1 as a therapeutic target. However, lack of simplified screening systems has limited the discovery of potent Pin1 inhibitors. We utilized phosphorylation-dependent binding of Pin1 to its specific substrate to develop a screening system for Pin1 inhibitors. Using this system, we screened a chemical library, and identified a novel selenium derivative as Pin1 inhibitor. Based on structure-activity guided chemical synthesis, we developed more potent Pin1 inhibitors that inhibited cancer cell proliferation. -- Highlights: •Novel screening for Pin1 inhibitors based on Pin1 binding is developed. •A novel selenium compound is discovered as Pin1 inhibitor. •Activity guided chemical synthesis of selenium derivatives resulted potent Pin1 inhibitors.

Microwave plasma enhanced chemical vapor deposition growth of few-walled carbon nanotubes using catalyst derived from an iron-containing block copolymer precursor

International Nuclear Information System (INIS)

Wang Peng; Lu, Jennifer; Zhou, Otto

2008-01-01

The microwave plasma enhanced chemical vapor deposition (MPECVD) method is now commonly used for directional and conformal growth of carbon nanotubes (CNTs) on supporting substrates. One of the shortcomings of the current process is the lack of control of the diameter and diameter distribution of the CNTs due to difficulties in synthesizing well-dispersed catalysts. Recently, block copolymer derived catalysts have been developed which offer the potential of fine control of both the size of and the spacing between the metal clusters. In this paper we report the successful growth of CNTs with narrow diameter distribution using polystyrene-block-polyferrocenylethylmethylsilane (PS-b-PFEMS) as the catalyst precursor. The study shows that higher growth pressure leads to better CNT growth. Besides the pressure, the effects on the growth of CNTs of the growth parameters, such as temperature and precursor gas ratio, are also studied

40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Butanaminium, N-(3-aminopropyl)-N...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B; CAS No...

SYNTHESIS OF METHACRYLATES FROM COAL-DERIVED SYNGAS

Energy Technology Data Exchange (ETDEWEB)

Jang, B.W.L.; Spivey, J.J.; Gogate, M.R.; Zoeller, J.R.; Colberg, R.D.; Choi, G.N.

1999-12-01

Research Triangle Institute (RTI), Eastman Chemical Company, and Bechtel have developed a novel process for synthesis of methyl methacrylate (MMA) from coal-derived syngas, under a contract from the US Department of Energy/Fossil Energy Technology Center (DOE/FETC). This project has resulted in five US patents (four already published and one pending publication). It has served as the basis for the technical and economic assessment of the production of this high-volume intermediate from coal-derived synthesis gas. The three-step process consists of the synthesis of a propionate from ethylene carbonylation using coal-derived CO, condensation of the propionate with formaldehyde to form methacrylic acid (MAA); and esterification of MAA with methanol to yield MMA. The first two steps, propionate synthesis and condensation catalysis, are the key technical challenges and the focus of the research presented here.

Predicting Chemical Toxicity from Proteomics and Computational Chemistry

Science.gov (United States)

2008-07-30

perfluorooctanoic acid , perfluorodecanoic acid , clofibrate , and diethylhexyl phthalate) show that the leading eigenvalue of the D/D matrix derived from embedded... clofibrate , and DEHP, show that this approach clusters the first three highly-fluorinated and mechanistically similar chemicals together, while

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 8. Curcuminoid-derived 3,5-bis(styryl)isoxazoles - Mechanochemical synthesis and antioxidant activity. DAISY R SHERIN KALLIKAT N RAJASEKHARAN. Regular Article Volume 128 Issue 8 August 2016 pp 1315-1319 ...

Recent Advances in Microbial Production of Aromatic Chemicals and Derivatives.

Science.gov (United States)

Noda, Shuhei; Kondo, Akihiko

2017-08-01

Along with the development of metabolic engineering and synthetic biology tools, various microbes are being used to produce aromatic chemicals. In microbes, aromatics are mainly produced via a common important precursor, chorismate, in the shikimate pathway. Natural or non-natural aromatics have been produced by engineering metabolic pathways involving chorismate. In the past decade, novel approaches have appeared to produce various aromatics or to increase their productivity, whereas previously, the targets were mainly aromatic amino acids and the strategy was deregulating feedback inhibition. In this review, we summarize recent studies of microbial production of aromatics based on metabolic engineering approaches. In addition, future perspectives and challenges in this research area are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Liquid Chromatography with Electrospray Ionization and Tandem Mass Spectrometry Applied in the Quantitative Analysis of Chitin-Derived Glucosamine for a Rapid Estimation of Fungal Biomass in Soil

Directory of Open Access Journals (Sweden)

Madelen A. Olofsson

2016-01-01

Full Text Available This method employs liquid chromatography-tandem mass spectrometry to rapidly quantify chitin-derived glucosamine for estimating fungal biomass. Analyte retention was achieved using hydrophilic interaction liquid chromatography, with a zwitter-ionic stationary phase (ZIC-HILIC, and isocratic elution using 60% 5 mM ammonium formate buffer (pH 3.0 and 40% ACN. Inclusion of muramic acid and its chromatographic separation from glucosamine enabled calculation of the bacterial contribution to the latter. Galactosamine, an isobaric isomer to glucosamine, found in significant amounts in soil samples, was also investigated. The two isomers form the same precursor and product ions and could not be chromatographically separated using this rapid method. Instead, glucosamine and galactosamine were distinguished mathematically, using the linear relationships describing the differences in product ion intensities for the two analytes. The m/z transitions of 180 → 72 and 180 → 84 were applied for the detection of glucosamine and galactosamine and that of 252 → 126 for muramic acid. Limits of detection were in the nanomolar range for all included analytes. The total analysis time was 6 min, providing a high sample throughput method.

Kojyl cinnamate ester derivatives promote adiponectin production during adipogenesis in human adipose tissue-derived mesenchymal stem cells.

Science.gov (United States)

Rho, Ho Sik; Hong, Soo Hyun; Park, Jongho; Jung, Hyo-Il; Park, Young-Ho; Lee, John Hwan; Shin, Song Seok; Noh, Minsoo

2014-05-01

The subcutaneous fat tissue mass gradually decreases with age, and its regulation is a strategy to develop anti-aging compounds to ameliorate the photo-aging of human skin. The adipogenesis of human adipose tissue-mesenchymal stem cells (hAT-MSCs) can be used as a model to discover novel anti-aging compounds. Cinnamomum cassia methanol extracts were identified as adipogenesis-promoting agents by natural product library screening. Cinnamates, the major chemical components of Cinnamomum cassia extracts, promoted adipogenesis in hAT-MSCs. We synthesized kojyl cinnamate ester derivatives to improve the pharmacological activity of cinnamates. Structure-activity studies of kojyl cinnamate derivatives showed that both the α,β-unsaturated carbonyl ester group and the kojic acid moiety play core roles in promoting adiponectin production during adipogenesis in hAT-MSCs. We conclude that kojyl cinnamate ester derivatives provide novel pharmacophores that can regulate adipogenesis in hAT-MSCs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Guest Editorial: The Professional Status of European Chemists and Chemical Engineers.

Science.gov (United States)

Salzer, Reiner; Taylor, Philip; Majcen, Nineta H; De Angelis, Francesco; Wilmet, Sophie; Varella, Evangelia; Kozaris, Ioannis

2015-07-06

Which country pays its chemists and chemical engineers the highest salaries? Where can I find a new job quickest? Which chemical sub-discipline offers most jobs? Reliable answers for these and other questions have been derived from the first European employment survey for chemists and chemical engineers, which was carried out in 2013. Here we publish the first general evaluation of the results of this survey. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and anticancer evaluation of (-1)- aretigenin derivatives

International Nuclear Information System (INIS)

Xu, Y.; Chen, G.

2014-01-01

Seven (-)-arctigenin derivatives 1-7 were designed and synthesized by using Mannich and acylation methods to improve the activity and bioavailability of (-)-arctigenin. Structures of compounds 1-7 were elucidated on the basis of spectroscopic analysis and chemical evidence. Anticancer activity of these compounds on SGC7901 was assayed in vitro. (author)

Synthesis and anticancer evaluation of (-1)- aretigenin derivatives

Energy Technology Data Exchange (ETDEWEB)

Xu, Y.; Chen, G. [Liaoning Univ. of Traditional Chinese Medicine, Dalian (China)

2014-10-15

Seven (-)-arctigenin derivatives 1-7 were designed and synthesized by using Mannich and acylation methods to improve the activity and bioavailability of (-)-arctigenin. Structures of compounds 1-7 were elucidated on the basis of spectroscopic analysis and chemical evidence. Anticancer activity of these compounds on SGC7901 was assayed in vitro. (author)

Mechanism for translocation of fluoroquinolones across lipid membranes

DEFF Research Database (Denmark)

Cramariuc, O.; Rog, T.; Javanainen, M.

2012-01-01

Classical atom-scale molecular dynamics simulations, constrained free energy calculations, and quantum mechanical (QM) calculations are employed to study the diffusive translocation of ciprofloxacin (CPFX) across lipid membranes. CPFX is considered here as a representative of the fluoroquinolone...... antibiotics class. Neutral and zwitterionic CPFX coexist at physiological pH, with the latter being predominant. Simulations reveal that only the neutral form permeates the bilayer, and it does so through a novel mechanism that involves dissolution of concerted stacks of zwitterionic ciprofloxacins....... Subsequent QM analysis of the observed molecular stacking shows the important role of partial charge neutralization in the stacks, highlighting how the zwitterionic form of the drug is neutralized for translocation. The findings propose a translocation mechanism in which zwitterionic CPFX molecules approach...

Surface grafting of zwitterionic polymers onto dye doped AIE-active luminescent silica nanoparticles through surface-initiated ATRP for biological imaging applications

Science.gov (United States)

Mao, Liucheng; Liu, Xinhua; Liu, Meiying; Huang, Long; Xu, Dazhuang; Jiang, Ruming; Huang, Qiang; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2017-10-01

Aggregation-induced emission (AIE) dyes have recently been intensively explored for biological imaging applications owing to their outstanding optical feature as compared with conventional organic dyes. The AIE-active luminescent silica nanoparticles (LSNPs) are expected to combine the advantages both of silica nanoparticles and AIE-active dyes. Although the AIE-active LSNPs have been prepared previously, surface modification of these AIE-active LSNPs with functional polymers has not been reported thus far. In this work, we reported a rather facile and general strategy for preparation of polymers functionalized AIE-active LSNPs through the surface-initiated atom transfer radical polymerization (ATRP). The AIE-active LSNPs were fabricated via direct encapsulation of AIE-active dye into silica nanoparticles through a non-covalent modified Stöber method. The ATRP initiator was subsequently immobilized onto these AIE-active LSNPs through amidation reaction between 3-aminopropyl-triethoxy-silane and 2-bromoisobutyryl bromide. Finally, the zwitterionic 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) was selected as model monomer and grafted onto MSNs through ATRP. The characterization results suggested that LSNPs can be successfully modified with poly(MPC) through surface-initiated ATRP. The biological evaluation results demonstrated that the final SNPs-AIE-pMPC composites possess low cytotoxicity, desirable optical properties and great potential for biological imaging. Taken together, we demonstrated that AIE-active LSNPs can be fabricated and surface modified with functional polymers to endow novel functions and better performance for biomedical applications. More importantly, this strategy developed in this work could also be extended for fabrication of many other LSNPs polymer composites owing to the good monomer adoptability of ATRP.

Third-order energy derivative corrections to the Kohn–Sham orbital ...

Indian Academy of Sciences (India)

Unknown

oped methods to assess the chemical reactivity indi- ces. So it became .... element of [η] can be obtained as the first derivative of εi with ... course, on the particular molecular system. Hardness .... obtained with sufficient accuracy from the finite-.

Versatile Chemical Derivatizations to Design Glycol Chitosan-Based Drug Carriers

Directory of Open Access Journals (Sweden)

Sung Eun Kim

2017-10-01

Full Text Available Glycol chitosan (GC and its derivatives have been extensively investigated as safe and effective drug delivery carriers because of their unique physiochemical and biological properties. The reactive functional groups such as the amine and hydroxyl groups on the GC backbone allow for easy chemical modification with various chemical compounds (e.g., hydrophobic molecules, crosslinkers, and acid-sensitive and labile molecules, and the versatility in chemical modifications enables production of a wide range of GC-based drug carriers. This review summarizes the versatile chemical modification methods that can be used to design GC-based drug carriers and describes their recent applications in disease therapy.

Correlated evolution of herbivory and food chemical discrimination in iguanian and ambush foraging lizards

OpenAIRE

William E. Cooper

2003-01-01

To efficiently locate and assess foods, animal sensory capacities and behavioral discriminations based on them must be appropriate for the diet and method of hunting. In lizards, actively foraging insectivores identify animal prey using lingually sampled chemical cues, but ambush foragers do not. Among plant eaters derived from active foragers, plant chemical discrimination is added to prey chemical discrimination, resulting in correlated evolution of plant diet and plant chemical discriminat...

Designing SQCRA as a Software to Semi-quantitative Chemical Risk Assessment in Workplace

Directory of Open Access Journals (Sweden)

Ali Karimi

2014-06-01

Full Text Available Background & Objectives : The aim of chemical risk assessment is to identify and evaluate risks originated from chemicals usages. This study aims to design a practical tool for facilitating chemical risk assessment. Methods: The proposed software was derived from chemical risk assessment method which was recommended by Ministry of Human Resources of Malaysia. All of the processes in question are designed in operating system software. Based on some revisions, this software was developed using Visual Basic (VB titled as SQCRA. The developed software was used for chemical risk assessment in Narges Vegetale Oil Company in Shiraz (center of Iran. Result: The output of software showed that the level of risk derived from sulfuric acid, phosphoric acid, aluminum sulphate, nickel catalyst, acetic acid used as a raw material were 2.4, 2.84, 2.3, 3.5 and 2.66, respectively. Moreover, risk rank and proposed control methods for each of these materials were determined. Conclusions : The developed software calculates the health risk level based on the degree of hazard and exposure in shorttime and without using risk matrix and chemical formula. After determining the risk rank, the software proposes the control procedures to reduce occupational exposure.

Estimating chemical emissions from home and personal care products in China

International Nuclear Information System (INIS)

Hodges, J.E.N.; Holmes, C.M.; Vamshi, R.; Mao, D.; Price, O.R.

2012-01-01

China's economy has grown significantly and concomitantly so has the demand for home and personal care (HPC) products. The detection of chemicals used in HPC products is increasing in profile as China strives to improve its environmental management. China is developing robust exposure models for use in regulatory risk-based assessments of chemicals, including those chemicals used in HPC products. Accurate estimates of chemical emissions play an important role within this. A methodology is presented to derive spatially refined emissions from demographic and economic indicators with large variations in emissions calculated, showing product usage being higher in East and South China. The less affordable a product, the greater the influence per capita Gross Domestic Product has on the product distribution. Lastly, more spatially resolved input data highlights greater variation of product use. Linking product sales data with population density increased the observed variability in absolute usage distribution of HPC products at the county > province > regional > country scale. - Highlights: ► We combined sales data with spatial datasets on demographic and economic indicators. ► Large variation in chemical emissions exists across China. ► More spatially resolved input data results in greater variation of product use. ► Results could be used to parameterise future exposure models in China. - A methodology to derive accurate estimates of chemical emissions for China using demographic and economic indicators.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

The oxazole and indole based heterocyclic photochromic fulgides were synthesized from their corresponding fulgenic acid derivatives by clay catalysed microwave irradiation methodology. Improved yields of fulgides were observed by the microwave irradiation method as compared other chemical methods employed so far ...

A novel chemo-enzymatic synthesis of hydrophilic phytosterol derivatives.

Science.gov (United States)

He, Wen-Sen; Hu, Di; Wang, Yu; Chen, Xue-Yan; Jia, Cheng-Sheng; Ma, Hai-Le; Feng, Biao

2016-02-01

In this study, a novel method was developed for chemo-enzymatic synthesis of hydrophilic phytosterol derivatives, phytosteryl polyethylene glycol succinate (PPGS), through an intermediate phytosteryl hemisuccinate (PSHS), which was first chemically prepared and subsequently coupled with polyethylene glycol (PEG) through lipase-catalyzed esterification. The chemical structure of intermediate and goal product were finally confirmed to be PSHS and PPGS by FT-IR, MS and NMR, suggesting that hydrophilic phytosterol derivatives were successfully synthesized. The effects of various parameters on the conversion of PSHS to PPGS were investigated and the highest conversion (>78%) was obtained under the selected conditions: 75 mmol/L PSHS, 1:2M ratio of PSHS to PEG, 50 g/L Novozym 435, 120 g/L 3 Å molecular sieves in tert-butanol, 55 °C, 96 h and 200 rpm. The solubility of phytosterols in water was significantly improved by coupling with PEG, facilitating the incorporation into a variety of foods containing water. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exohedral and skeletal rearrangements in the molecules of fullerene derivatives

Energy Technology Data Exchange (ETDEWEB)

Ignat' eva, Daria V; Ioffe, I N; Troyanov, Sergey I; Sidorov, Lev N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2011-07-31

The data on the migration of monoatomic addends, perfluoroalkyl and more complex organic groups in the molecules of fullerene derivatives published mainly in the last decade are analyzed. Skeletal rearrangements of the carbon cage occurring during chemical reactions are considered.

Chemical Pleurodesis Using Doxycycline and Viscum album Extract

Directory of Open Access Journals (Sweden)

Kyung Sub Song

2017-08-01

Full Text Available Background: In chemical pleurodesis for managing pulmonary air leak, tetracycline derivatives are commonly used, and their effectiveness has been established in many studies. Recently, a Viscum album extract was used in chemical pleurodesis. We compared the effects of V. album with those of a tetracycline derivative (doxycycline to demonstrate the therapeutic effectiveness of the V. album extract in chemical pleurodesis for managing pulmonary air leak. Methods: Between October 2010 and October 2016, chemical pleurodesis was performed using doxycycline in 40 patients and the V. album extract in 37 patients. Thirty-three patients were in the postoperative state after pulmonary resection, and 44 patients suffered from spontaneous pneumothorax. Results: No statistically significant difference in the success rate was observed between the 2 groups (V. album e xtract a nd d oxycycline . In b oth groups, chest pain w as t he m ost common complication. More patients in the doxycycline group complained of severe chest pain (42.1% vs. 13.5%, p=0.006. In the V. album extract group, 24.3% of the patients required a chest tube to drain the pleural effusion after cessation of the air leak (doxycycline group: 5%, p=0.022. Further, the amount of pleural effusion drained on the day after the last chemical pleurodesis in the V. album extract group was greater than that in the doxycycline group (162.2±170.2 mL vs. 97.0±77.2 mL, p=0.032. All patients were discharged from the hospital without complications after pleural effusion drainage. Conclusion: Considering that treatment using the V. album extract was less painful, V. album might be a feasible option for chemical pleurodesis. However, pleural effusion should be monitored carefully when using V. album extract for treating patients suffering from air leak.

Anti-trypanosomal activities and structural chemical properties of selected compound classes.

Science.gov (United States)

Ponte-Sucre, Alicia; Bruhn, Heike; Schirmeister, Tanja; Cecil, Alexander; Albert, Christian R; Buechold, Christian; Tischer, Maximilian; Schlesinger, Susanne; Goebel, Tim; Fuß, Antje; Mathein, Daniela; Merget, Benjamin; Sotriffer, Christoph A; Stich, August; Krohne, Georg; Engstler, Markus; Bringmann, Gerhard; Holzgrabe, Ulrike

2015-02-01

Potent compounds do not necessarily make the best drugs in the market. Consequently, with the aim to describe tools that may be fundamental for refining the screening of candidates for animal and preclinical studies and further development, molecules of different structural classes synthesized within the frame of a broad screening platform were evaluated for their trypanocidal activities, cytotoxicities against murine macrophages J774.1 and selectivity indices, as well as for their ligand efficiencies and structural chemical properties. To advance into their modes of action, we also describe the morphological and ultrastructural changes exerted by selected members of each compound class on the parasite Trypanosoma brucei. Our data suggest that the potential organelles targeted are either the flagellar pocket (compound 77, N-Arylpyridinium salt; 15, amino acid derivative with piperazine moieties), the endoplasmic reticulum membrane systems (37, bisquaternary bisnaphthalimide; 77, N-Arylpyridinium salt; 68, piperidine derivative), or mitochondria and kinetoplasts (88, N-Arylpyridinium salt; 68, piperidine derivative). Amino acid derivatives with fumaric acid and piperazine moieties (4, 15) weakly inhibiting cysteine proteases seem to preferentially target acidic compartments. Our results suggest that ligand efficiency indices may be helpful to learn about the relationship between potency and chemical characteristics of the compounds. Interestingly, the correlations found between the physico-chemical parameters of the selected compounds and those of commercial molecules that target specific organelles indicate that our rationale might be helpful to drive compound design toward high activities and acceptable pharmacokinetic properties for all compound families.

Incorporation of fluconazole in copolymer PMMA-g-PEG derivatives

International Nuclear Information System (INIS)

Silveira, B.M.; Santos, V.M.R. dos; Novack, K.M.; Lopes, S.A.

2014-01-01

The graft copolymer PMMA-g-PEG went through chemical transformations in its chain through acetylation, halogenation, methylation and esterification followed by hydrolysis reactions. Subsequently, the copolymer PMMA-g-PEG derivatives passed through the process of emulsification and incorporation of the drug fluconazole. Derivatives copolymers were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) after incorporation in order to evaluate their effectiveness. The efficiency of incorporation was observed and it was also verified that the complexity of polymer chain influence in the incorporated fluconazole content. (author)

Preparation and protection of silver nanoparticles with chitosan derivative

International Nuclear Information System (INIS)

Nguyen Thi Kim Cuc; Cao Van Du; Nguyen Cuu Khoa; Tran Ngoc Quyen

2013-01-01

In this paper, nano silver solution is prepared and stabilized by chitosan dihydroxyphenyl acetamide (CDHPA). Chitosan is a natural carbohydrate polymer deriving from chitin that has biodegradable, biocompatible, antibacterial and antifungal properties, so when conjugation of the polymer and silver nanoparticles could be expected to increase bactericidal features of the obtained product. The chemical and physical methods were used to characterize the chitosan derivative such as transmission spectrum (UV-Vis), IR spectrum, nuclear magnetic resonance (1H-NMR). Morphology of the obtained nano silver particles were observed by transmission electron microscopy (TEM). (author)

Local functional derivative of the total energy and the shell structure in atoms and molecules

NARCIS (Netherlands)

Pino, R.; Markvoort, Albert. J.; Santen, van R.A.; Hilbers, P.A.J.

2003-01-01

The full and local Thomas–Fermi–Dirac energy functional derivatives are evaluated at Hartree–Fock densities for several atoms and molecules. These functions are interpreted as local chemical potentials and related mainly to kinetic energy functional derivatives. They are able to reveal the shell

Novel amphiphilic poly(dimethylsiloxane) based polyurethane networks tethered with carboxybetaine and their combined antibacterial and anti-adhesive property

Science.gov (United States)

Jiang, Jingxian; Fu, Yuchen; Zhang, Qinghua; Zhan, Xiaoli; Chen, Fengqiu

2017-08-01

The traditional nonfouling materials are powerless against bacterial cells attachment, while the hydrophobic bactericidal surfaces always suffer from nonspecific protein adsorption and dead bacterial cells accumulation. Here, amphiphilic polyurethane (PU) networks modified with poly(dimethylsiloxane) (PDMS) and cationic carboxybetaine diol through simple crosslinking reaction were developed, which had an antibacterial efficiency of 97.7%. Thereafter, the hydrolysis of carboxybetaine ester into zwitterionic groups brought about anti-adhesive properties against bacteria and proteins. The surface chemical composition and wettability performance of the PU network surfaces were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle analysis. The surface distribution of PDMS and zwitterionic segments produced an obvious amphiphilic heterogeneous surface, which was demonstrated by atomic force microscopy (AFM). Enzyme-linked immunosorbent assays (ELISA) were used to test the nonspecific protein adsorption behaviors. With the advantages of the transition from excellent bactericidal performance to anti-adhesion and the combination of fouling resistance and fouling release property, the designed PDMS-based amphiphilic PU network shows great application potential in biomedical devices and marine facilities.

Physical and chemical characterizations of biochars derived from different agricultural residues

Science.gov (United States)

Jindo, K.; Mizumoto, H.; Sawada, Y.; Sanchez-Monedero, M. A.; Sonoki, T.

2014-08-01

Biochar has received large attention as a strategy to tackle against carbon emission. Not only carbon fixation has been carried out but also other merits for agricultural application due to unique physical and chemical character such as absorption of contaminated compounds in soil, trapping ammonia and methane emission from compost, and enhancement of fertilizer quality. In our study, different local waste feed stocks (rice husk, rice straw, wood chips of apple tree (Malus Pumila) and oak tree (Quercus serrata)), in Aomori, Japan, were utilized for creating biochar with different temperature (400-800 °C). Concerning to the biochar production, the pyrolysis of lower temperature had more biochar yield than higher temperature pyrolysis process. On the contrary, surface areas and adsorption characters have been increased as increasing temperature. The proportions of carbon content in the biochars also increased together with increased temperatures. Infrared-Fourier spectra (FT-IR) and 13C-NMR were used to understand carbon chemical compositions in our biochars, and it was observed that the numbers of the shoulders representing aromatic groups, considered as stable carbon structure appeared as the temperature came closer to 600 °C, as well as in FT-IR. In rice materials, the peak assigned to SiO2, was observed in all biochars (400-800 °C) in FT-IR. We suppose that the pyrolysis at 600 °C creates the most recalcitrant character for carbon sequestration, meanwhile the pyrolysis at 400 °C produces the superior properties as a fertilizer by retaining volatile and easily labile compounds which promotes soil microbial activities.

Synthesis of 3-acetyl-N-aryl-4-diethylaminoselenet-2(2H)-imines from 4-diethylamino-3-butyn-2-one and aryl isoselenocyanates

OpenAIRE

Atanassov, Plamen K; Linden, Anthony; Heimgartner, Heinz

2004-01-01

The reaction of aryl isoselenocyanates (1a-d) with 4-diethylamino-3-butyn-2-one (6) in refluxing tetrahydrofuran afforded N-arylselenet-2(2H)-imines (7) in moderate yields. The structure of the stable 4-bromophenyl derivative (7b) has been established by X-Ray crystallography. A stepwise cycloaddition via an intermediate zwitterion (A/A¢) is proposed as the reaction mechanism. In boiling tetrahydrofuran, the selenetimines (7) are in equilibrium with ketenimines (B), which were intercepted by ...

Chemical potential of one-dimensional simple harmonic oscillators

International Nuclear Information System (INIS)

Mungan, Carl E

2009-01-01

Expressions for the chemical potential of an Einstein solid, and of ideal Fermi and Bose gases in an external one-dimensional oscillatory trap, are calculated by two different methods and are all found to share the same functional form. These derivations are easier than traditional textbook calculations for an ideal gas in an infinite three-dimensional square well. Furthermore, the results indicate some important features of chemical potential that could promote student learning in an introductory course in statistical mechanics at the undergraduate level.

Wave propagation in a quasi-chemical equilibrium plasma

Science.gov (United States)

Fang, T.-M.; Baum, H. R.

1975-01-01

Wave propagation in a quasi-chemical equilibrium plasma is studied. The plasma is infinite and without external fields. The chemical reactions are assumed to result from the ionization and recombination processes. When the gas is near equilibrium, the dominant role describing the evolution of a reacting plasma is played by the global conservation equations. These equations are first derived and then used to study the small amplitude wave motion for a near-equilibrium situation. Nontrivial damping effects have been obtained by including the conduction current terms.

Noise-resistant spectral features for retrieving foliar chemical parameters

Science.gov (United States)

Foliar chemical constituents are important indicators for understanding vegetation growing status and ecosystem functionality. Provided the noncontact and nondestructive traits, the hyperspectral analysis is a superior and efficient method for deriving these parameters. In practical implementation o...

Synthesis and Characterization of New Polyamides from 1,2-Bis hydrazine Derivatives

International Nuclear Information System (INIS)

Salaha, A.; Abdel-Bary, E.M.; Kandilea, N.G.

2005-01-01

Preparation of polyamides having different chemical structures allows obtaining new materials with different mechanical and physical properties. The difference in the chemical structure depends mainly on the starting reactants used in condensation polymerization of polyamides. In this paper the synthesis of new polyamides based on the condensation polymerization of 1,2- Bis(3-carboxyacryloyl or carboxybenzoyl) hydrazine derivatives and various diamines has been described. The polymers obtained were characterized using spectroscopic and X-ray analysis. Besides thermal stability and electrical conductivity have been evaluated and correlated with the chemical structure of the polyamides obtained

Terrestrial ecotoxicity of eight chemicals in a systematic approach

Energy Technology Data Exchange (ETDEWEB)

Hund-Rinke, K.; Simon, M. [Fraunhofer Inst. for Molecular Biology and Applied Ecology, Schmallenberg (Germany)

2005-07-01

Background and objective. Terrestrial ecotoxicity data are required for many research purposes. The data are derived either from the literature or elaborated by own investigations. As the terrestrial toxicity tests are usually time-consuming and labour intensive, the experiments are performed with a limited number of test organisms and soils. In the context of a project sponsored by CEFIC-LRI (European Chemical Industry Council - Long-Range Research Initiative), EC{sub 50}-values were systematically elaborated for eight chemicals with a wide range of logK{sub ow}-values (CdCl{sub 2}, Trinitrotoluene, 3,4-dichloroaniline, 2,4-dichlorophenol, Tributyltinchloride, Pentachlorophenol, Benzo(a)pyrene, p,p-dichloro-2,2-diphenyl-1,1,1-trichloroethane). The substances were selected covering a broad range of physico-chemical and ecotoxicological properties. As toxicity endpoints, microbial activities, plant germination and growth as well as reproduction of earthworms and collembola were determined. As such systematic investigations are rarely performed and for some substances no data existed, the data pool is made available to the scientific community. Methods. All toxicity tests were conducted on three different soil types (sandy soil, silty soil, loamy soil), according to ISO and OECD guidelines Results, discussion, conclusion and outlook. The different toxicities of the chemicals, the influence of soil properties on bioavailability as well as different sensitivities of test organisms and test parameters are reflected by the EC{sub 50}-values. The results showed that the EC{sub 50}-values calculated on the basis of nominal concentrations can significantly vary from EC{sub 50}-values derived from analytical concentrations for some substances. To avoid false conclusions, this has to be considered especially when concentrations determined in the field are compared with toxicity data obtained from the literature or calculated on the basis of nominal concentrations. Moreover

Reaction pathways of biomass-derived oxygenates on noble metal surfaces

Science.gov (United States)

McManus, Jesse R.

As the global demand for energy continues to rise, the environmental concerns associated with increased fossil fuel consumption have motivated the use of biomass as an alternative, carbon-renewable energy feedstock. Controlling reactive chemistry of the sugars that comprise biomass through the use of catalysis becomes essential in effectively producing green fuels and value-added chemicals. Recent work on biomass conversion catalysts have demonstrated the efficacy of noble metal catalyst systems for the reforming of biomass to hydrogen fuel, and the hydrodeoxygenation of biomass-derived compounds to value-added chemicals. In particular, Pt and Pd surfaces have shown considerable promise as reforming catalysts in preliminary aqueous phase reforming studies. It becomes important to understand the mechanisms by which these molecules react on the catalyst surfaces in order to determine structure-activity relationships and bond scission energetics as to provide a framework for engineering more active and selective catalysts. Fundamental surface science techniques provide the tools to do this; however, work in this field has been so far limited to simple model molecules like ethanol and ethylene glycol. Herein, temperature programmed desorption and high resolution electron energy loss spectroscopy are utilized in an ultra-high vacuum surface science study of the biomass-derived sugar glucose on Pt and Pd single crystal catalysts. Overall, it was determined that the aldehyde function of a ring-open glucose molecule plays an integral part in the initial bonding and reforming reaction pathway, pointing to the use of aldoses glycolaldehyde and glyceraldehyde as the most appropriate model compounds for future studies. Furthermore, the addition of adatom Zn to a Pt(111) surface was found to significantly decrease the C-H and C-C bond scission activity in aldehyde containing compounds, resulting in a preferred deoxygenation pathway in opposition to the decarbonylation pathway

Determination of borneol and other chemical compounds of ...

African Journals Online (AJOL)

Purpose: To determine borneol and other chemical compounds of essential oil derived from the exudate of Dryobalanops aromatica in Malaysia. Methods: Exudate was collected from D. aromatica and subjected to fractional distillation to obtain essential oil. Gas chromatography-mass spectrometry (GC-MS) was performed ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Time-dependent density functional theory (TDDFT)was used to assign the electronic absorption bands observed experimentally. Pyridine derivative showed two bands at shorter λmax compared to the others, both experimentally and theoretically. The NMR chemical shifts were computed for protons and carbons using GIAO ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 6. Synthesis and anti-inflammatory activity of 3-indolyl pyridine derivatives through one-pot multi component reaction. Prakasam Thirumurugan S Mahalaxmi Paramasivan T Perumal. Full Papers Volume 122 Issue 6 November 2010 pp 819-832 ...

Prediction of proton chemical shifts in RNA - Their use in structure refinement and validation

International Nuclear Information System (INIS)

Cromsigt, Jenny A.M.T.C.; Hilbers, Cees W.; Wijmenga, Sybren S.

2001-01-01

An analysis is presented of experimental versus calculated chemical shifts of the non-exchangeable protons for 28 RNA structures deposited in the Protein Data Bank, covering a wide range of structural building blocks. We have used existing models for ring-current and magnetic-anisotropy contributions to calculate the proton chemical shifts from the structures. Two different parameter sets were tried: (i) parameters derived by Ribas-Prado and Giessner-Prettre (GP set) [(1981) J. Mol. Struct.,76, 81-92.]; (ii) parameters derived by Case [(1995) J. Biomol. NMR, 6, 341-346]. Both sets lead to similar results. The detailed analysis was carried using the GP set. The root-mean-square-deviation between the predicted and observed chemical shifts of the complete database is 0.16 ppm with a Pearson correlation coefficient of 0.79. For protons in the usually well-defined A-helix environment these numbers are, 0.08 ppm and 0.96, respectively. As a result of this good correspondence, a reliable analysis could be made of the structural dependencies of the 1 H chemical shifts revealing their physical origin. For example, a down-field shift of either H2' or H3' or both indicates a high-syn/syn χ-angle. In an A-helix it is essentially the 5'-neighbor that affects the chemical shifts of H5, H6 and H8 protons. The H5, H6 and H8 resonances can therefore be assigned in an A-helix on the basis of their observed chemical shifts. In general, the chemical shifts were found to be quite sensitive to structural changes. We therefore propose that a comparison between calculated and observed 1 H chemical shifts is a good tool for validation and refinement of structures derived from NOEs and J-couplings