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Find video protocols related to scientific articles indexed in Pubmed.
FeP Nanoparticles Film Grown on Carbon Cloth: An Ultrahighly Active 3D Hydrogen Evolution Cathode in Both Acidic and Neutral Solutions.
ACS Appl Mater Interfaces
PUBLISHED: 11-18-2014
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In this Letter, we demonstrate the direct growth of FeP nanoparticles film on carbon cloth (FeP/CC) through low-temperature phosphidation of its Fe3O4/CC precursor. Remarkably, when used as an integrated 3D hydrogen evolution cathode, this FeP/CC electrode exhibits ultrahigh catalytic activity comparable to commercial Pt/C and good stability in acidic media. This electrode also performs well in neutral solutions. This work offers us the most cost-effective and active 3D cathode toward electrochemical water splitting for large-scale hydrogen fuel production.
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Chitosan-Templated Synthesis of Few-Layers Boron Nitride and its Unforeseen Activity as a Fenton Catalyst.
Chemistry
PUBLISHED: 09-30-2014
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A novel procedure for the preparation of few-layers boron nitride (BN), either as films or as suspended BN platelets, is presented, based on the pyrolysis of chitosan, which serves both as a matrix to embed ammonium borate and as a template for BN synthesis. The resulting BN samples are characterized by XRD, Raman and X-ray photoelectron spectroscopy, and by TEM and AFM imaging. The samples exhibit deep UV emission, which is characteristic of high quality BN. This template synthesis and the easy exfoliation of BN platelets facilitate the use of BN as an extremely high-efficiency Fenton catalyst for the generation of highly aggressive hydroxyl radicals in water.
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Synthesis and Direct C2 Functionalization of Imidazolium and 1,2,4-Triazolium N-Imides.
J. Org. Chem.
PUBLISHED: 09-27-2014
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Pd-catalyzed direct C2 arylation and Cu-catalyzed direct one-pot alkynylation/intramolecular cyclization of azolium N-imides are reported. Various acetylenes, aryl iodides, and 1-alkyl substituents were examined. The mild protocol allows direct C2 arylation of azolium N-imides without the use of specialized reagents together with novel one-pot regioselective preparations of imidazole-pyrazolo and pyrazolo-1,2,4-triazole ring systems. The electronic properties of selected examples were examined by fluorescence spectroscopy.
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Can Gap Tuning Schemes of Long-Range Corrected Hybrid Functionals Improve the Description of Hyperpolarizabilities?
J Phys Chem B
PUBLISHED: 09-11-2014
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Long-range corrected hybrid density functionals (LC-DFT), with range separation parameters optimally tuned to obey Koopmans' theorem, are used to calculate the first-order hyperpolarizabilities of prototypical charge-transfer compounds p-nitroaniline (PNA) and dimethylamino nitrostilbene (DANS) in the gas phase and various solvents. It is shown that LC-DFT methods with default range separation parameters tend to underestimate hyperpolarizabilities (most notably in solution) and that the tuning scheme can sharply improve results, especially in the cases when the standard LC-DFT errors are largest. Nonetheless, we also identify pathological cases (two pyrrole derivatives) for which LC-DFT underestimates the hyperpolarizabilities, regardless of tuning. It is noted that such pathological cases do not follow the usual inverse relation between the hyperpolarizability and amount of exact exchange, and thus this behavior may serve as a diagnostic tool for the adequacy of LC-DFT.
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Crystal structure of 1-benzoyl-3-(4-fluoro-phen-yl)thio-urea.
Acta Crystallogr Sect E Struct Rep Online
PUBLISHED: 09-01-2014
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The title compound, C14H11FN2OS, contains two mol-ecules (A and B) in the asymmetric unit, with different conformations. In mol-ecule A, the dihedral angles between the central thio-urea grouping and the phenyl and fluoro-benzene rings are 28.77?(8) and 41.82?(8)°, respectively, and the dihedral angle between the ring planes is 70.02?(9)°. Equivalent data for mol-ecule B are 8.46?(8), 47.78?(8) and 52.99?(9)°, respectively. Both mol-ecules feature an intra-molecular N-H?O hydrogen bond, which closes an S(6) ring. In the crystal, A+B dimers linked by pairs of N-H?S hydrogen bonds generate R 2 (2)(8) loops.
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Spectroscopic Investigation, Effect of Solvent Polarity and Fluorescence Quenching of a New D-?-A Type Chalcone Derivative.
J Fluoresc
PUBLISHED: 08-30-2014
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A new chalcone derivative 3-(1-methyl-1H-pyrrol-2-yl)-1-naphthalen-2-yl propenone (MPNP) with electron donor-acceptor group has been synthesized and characterized by IR, (1)HNMR, (13)C NMR and X- ray crystallography. Electronic absorption and emission spectra of MPNP have been studied in solvents of different polarity. A remarkable red shift was observed in the emission spectrum of MPNP compared to the absorption spectrum upon increasing the solvent polarity, indicating a higher dipole moment in the excited state than in the ground state and the transition involved are ?-?* with charge transfer character. Lippert-Mataga and Reichardts correlations were used to estimate the change in dipole moments (??); suggest that the emissive state of MPNP is of strong ICT character. Fluorescence quantum yield (?f) of MPNP was correlated with empirical solvent polarity parameter ET(30), and it is observed that ?f increases with increase in solvent polarity of polar aprotic solvents and decrease in alcoholic solvents. The interaction of MPNP with colloidal silver nanoparticles (AgNPs) was also studied in ethanol and ethylene glycol using steady state emission measurements. The fluorescence quenching data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching of MPNP by Ag NPs.
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Holey graphene nanosheets: large-scale rapid preparation and their application toward highly-effective water cleaning.
Nanoscale
PUBLISHED: 08-27-2014
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In this communication, we demonstrate the rapid large-scale preparation of holey graphene nanosheets (h-G NSs) via low-temperature thermal treatment of oxidized graphite powder obtained by a modified Brodie method in air. The h-G NSs have nanopores with a high specific surface area and large pore volume. When used as a water cleaning agent, they exhibit excellent absorption performances for oils, solvents and dyes.
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Ni2P nanoparticle films supported on a Ti plate as an efficient hydrogen evolution cathode.
Nanoscale
PUBLISHED: 08-22-2014
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In this communication, we report a two-step strategy for low-temperature construction of Ni2P nanoparticle films supported on a Ti plate (Ni2P/Ti). When used as an integrated hydrogen evolution cathode, the Ni2P/Ti electrode exhibits remarkable catalytic activity, superior stability and nearly 100% Faradaic efficiency in acidic solutions, and it needs overpotentials of 138 and 188 mV to afford current densities of 20 and 100 mA cm(-2), respectively.
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Graphitic carbon nitride nanosheets: one-step, high-yield synthesis and application for Cu2+ detection.
Analyst
PUBLISHED: 08-20-2014
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In this article we report on the one-step, rapid, high-yield synthesis of graphitic carbon nitride (g-C3N4) nanosheets for the first time. The nanosheets were obtained by pyrolyzing a melamine-KBH4 mixture under Ar. As a fluorosensor for Cu(2+), the g-C3N4 nanosheets exhibit a detection limit as low as 0.5 nM and high selectivity in buffer solutions, and this sensor was applied to the analysis of lake water samples. The electrogenerated chemiluminescence (ECL) behavior of the g-C3N4 nanosheets using Na2S2O8 as the coreactant was also studied. Results suggest that the ECL intensity of the g-C3N4 nanosheets was linear over concentrations of 0-45 nM, with a detection limit of 1.2 nM for Cu(2+).
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Microwave assisted synthesis and QSAR study of novel NSAID acetaminophen conjugates with amino acid linkers.
Org. Biomol. Chem.
PUBLISHED: 08-02-2014
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Novel, non-steroidal anti-inflammatory drug (NSAID), acetaminophen conjugates 6a–l with amino acid linkers were synthesized utilizing benzotriazole chemistry. Biological data acquired for all the novel bis-conjugates showed (a) some bis-conjugates (6d, 6e, 6h, and 6k) exhibit more potent anti-inflammatory activity than their parent drugs, (b) the potent bis-conjugates show no visible stomach lesions in contrast to parent drugs which are highly ulcerogenic, and (c) that the potent bio-active compounds have no mortality rates or toxic symptoms at 5 fold the applied anti-inflammatory dosage. A statistically significant QSAR model describing the anti-inflammatory properties of 6a–l (N = 15, n = 3, R(2) = 0.891, R(2)cvOO = 0.770, R(2)cvMO = 0.796, F = 29.904, s(2) = 0.011) was obtained employing CODESSA-Pro that validated the observed bio-activity.
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In-Situ Confined Growth of Monodisperse Pt Nanoparticle@Graphene Nanobox Composites as Electrocatalytic Nanoreactors.
Small
PUBLISHED: 07-31-2014
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Monodisperse Pt nanoparticles (NPs) studded in a three-dimensional (3D) graphene nanobox are successfully synthesized through a simple in-situ confined growth route for the first time. The nano-zeolite A was used as a 3D substrate for in-situ growth of tri-layered graphenes on the crystal-surfaces, meanwhile, the inner micropores of which can also be utilized for the confined growth of Pt nanoparticles. The graphene sheets are curved on the edges to form a 3D hollow box morphology, where the monodisperse Pt nanoparticles are homogeneously studded on the inner surfaces. Moreover, the Pt content can be regulated from ?8 to 50 wt%, and the particle size can be tuned from 2-5 nm by varying the pristine Pt-ion loading amount and CVD temperature. The Pt NP@graphene nanoboxes possess not only large pore volumes to effectively accommodate large amounts of oxygen, but also supply excellent electrical conductivity for the fast transfer of electrons (?3.96 e(-) ), resulting in a high efficiency (175 mA/mg Pt) and long-term stability (above 1000 cycles) for the oxygen reduction reaction.
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Catalysis by metal-organic frameworks in water.
Chem. Commun. (Camb.)
PUBLISHED: 07-25-2014
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Metal-organic frameworks (MOFs) having a large surface area and porosity as well as a high density of transition metals are increasingly used as heterogeneous catalysts for organic reactions. However, one of the main limitations of various MOFs has been their lack of structural stability that led to an assumption that MOFs are unstable materials, particularly in water or polar solvents. However, since a few years ago the hydrothermal stability of several MOFs such as MIL-101(Cr), MIL-53(Al) and ZIF-8 has been demonstrated and, hence, they can be used as solid catalysts in the aqueous phase. The present review is aimed at showing that there are a sufficiently large number of reports proving that certain MOFs can be used as reusable catalysts in water as the solvent. The use of water as the solvent has considerable advantages from the environmental point of view and affordability. Water can be the solvent of choice for hydrolytic processes, but MOFs have been reported as catalysts in water even for esterifications and C-C couplings. Considering that the synthesis of new MOFs is an active area of research and the flexibility in the selection of transition metals and organic linkers, these materials can be prepared with the required hydrophilicity/hydrophobicity to adapt specifically for catalysis in aqueous phase.
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Three-dimensional interconnected network of nanoporous CoP nanowires as an efficient hydrogen evolution cathode.
Phys Chem Chem Phys
PUBLISHED: 07-14-2014
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For the first time we demonstrate the topotactic synthesis of a three-dimensional (3D) interconnected network of nanoporous CoP nanowires directly on a Ti substrate (np-CoP NWs/Ti) via low-temperature phosphidation of a Co2(OH)2(CO3)2/Ti precursor and its further use as a highly efficient hydrogen evolution cathode.
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Synthesis and Sensor Activity of a PET-based 1,8-naphthalimide Probe for Zn(2+) and pH Determination.
J Fluoresc
PUBLISHED: 07-12-2014
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A novel blue-emitting 1,8-naphthalimide fluorophore designed as a molecular PET-based probe for determination of pH and detection of transition metal ions in the environment was successfully synthesized. Novel compound was configured on the "fluorophore-spacer-receptor" format. Due to the tertiary amine receptor the novel system showed "off-on" switching properties under the transition from alkaline to acid media (FE?=?3.2) and in the presence of Zn(2+) ions (FE?=?2.5). The results obtained illustrate the high potential of the synthesized blue-emitting 1,8-naphthalimide fluorophore as an efficient pH chemosensing material and a selective probe for Zn(2+) ions.
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Activated carbon nanotubes: a highly-active metal-free electrocatalyst for hydrogen evolution reaction.
Chem. Commun. (Camb.)
PUBLISHED: 07-09-2014
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In this communication, for the first time, we report on the development and utilization of activated carbon nanotubes (CNTs) as a highly-active metal-free electrocatalyst for the hydrogen evolution reaction (HER) with good durability in acidic electrolytes. This catalyst shows an onset overpotential and an exchange current density of 100 mV and 16.0 × 10(-3) mA cm(-2), respectively. The possible catalytic mechanism for the HER is also proposed.
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A Cost-Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity: FeP Nanowire Array as the Active Phase.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 07-03-2014
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Iron is the cheapest and one of the most abundant transition metals. Natural [FeFe]-hydrogenases exhibit remarkably high activity in hydrogen evolution, but they suffer from high oxygen sensitivity and difficulty in scale-up. Herein, an FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its ?-FeOOH NA/Ti precursor through a low-temperature phosphidation reaction. When applied as self-supported 3D hydrogen evolution cathode, the FeP NA/Ti electrode shows exceptionally high catalytic activity and good durability, and it only requires overpotentials of 55 and 127?mV to afford current densities of 10 and 100?mA?cm(2) , respectively. The excellent electrocatalytic performance is promising for applications as non-noble-metal HER catalyst with a high performance-price ratio in electrochemical water splitting for large-scale hydrogen fuel production.
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An experimental and density functional study on conformational and spectroscopic analysis of 5-methoxyindole-2-carboxylic acid.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 06-29-2014
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In this article, a brief conformational and spectroscopic characterization of 5-methoxyindole-2-carboxylic acid (5-MeOICA) via experimental techniques and applications of quantum chemical methods is presented. The conformational analysis of the studied molecule was determined theoretically using density functional computations for ground state, and compared with previously reported experimental findings. The vibrational transitions were examined by measured FT-IR and FT-Raman spectroscopic data, and also results obtained from B3LYP and CAM-B3LYP functionals in combination with 6-311++G(d,p) basis set. The recorded proton and carbon NMR spectra in DMSO solution were analyzed to obtain the exact conformation. Due to intermolecular hydrogen bondings, NMR calculations were performed for the dimeric form of 5-MeOICA and so chemical shifts of those protons were predicted more accurately. Finally, electronic properties of steady compound were identified by a comparative study of UV absorption spectra in ethanol and water solution and TD-DFT calculations.
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Spectroscopy of homo- and heterodimers of silver and gold nanocubes as a function of separation: a DDA simulation.
J Phys Chem A
PUBLISHED: 06-25-2014
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The plasmonic fields of silver and gold nanocubes are known to be among the strongest of any plasmonic metallic nanoparticles. Aggregation dominates their use in imaging and sensing applications due to the resulting enhancement of the plasmonic field in between the nanoparticles (hot spots). The first step in the aggregation process is dimerization. In the present work, we used the discrete dipole approximation (DDA) to calculate the interdimer separation dependence of the absorption and scattering components of the localized surface plasmon resonance (LSPR) extinction of homo and heterodimers of Ag and Au nanocubes when excited parallel to their interparticle axis. We also examined the changes in the nanocube surface plasmonic field distributions as the dimer separation was varied. The results from the homodimers were as expected: as the cubes were brought together, there was a red shift in the primary plasmon band in accordance with the universal scaling law. Additionally, as the particles moved together, scattering contributed more to the overall extinction. By examining the E-field distributions, we found that the hot spot geometry changes abruptly at small separations. At very short distances, the hot spot is located between the adjacent faces and away from the corners of these faces. At larger separations it moves toward the adjacent corners. We observed apparently anomalous behavior for the heterodimer. First, the E-field resulting from excitation of the Ag dominated plasmon resonance was significantly weaker than expected. Second, the red shift of the gold dominated plasmon resonance did not follow the universal scaling law. The most likely explanation for these observations is that the silver plasmon mixes strongly with the energetically resonant, but nonplasmonic, gold interband transition to form a hybrid resonance that produces weaker overall field intensity on the two nanocubes at short separation.
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Copper nanoparticles supported on doped graphenes as catalyst for the dehydrogenative coupling of silanes and alcohols.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 05-27-2014
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Copper nanoparticles (NPs) supported on a series of undoped and doped graphene materials (Gs) have been obtained by pyrolysis of alginate or chitosan biopolymers, modified or not with boric acid, containing Cu(2+) ions at 900?°C under inert atmosphere. The resulting Cu-G materials containing about 17?wt?% Cu?NPs (from 10 to 200?nm) exhibit high catalytic activity for the dehydrogenative coupling of silanes with alcohols. The optimal material consisting on Cu-(B)G is more efficient than Cu?NPs on other carbon supports.
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Analysis of surface and bulk properties of amphiphilic drug ibuprofen and surfactant mixture in the absence and presence of electrolyte.
Colloids Surf B Biointerfaces
PUBLISHED: 05-21-2014
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In the present work, the micellization, adsorption and aggregation behavior of mixed drug-surfactant systems, in the absence and presence of electrolyte (100mM NaCl) were investigated by surface tension and fluorescence measurements. The critical micelle concentrations (cmc) of the mixtures fall between the values of the individual components, which indicate nonideal behavior of mixing of the components. On the basis of regular solution theory (RST), the micellar mole fractions of surfactant (X1) and interaction parameter in solution (?) were evaluated, while their interfacial mole fractions (X1(?)) and interaction parameters at the interface (?(?)) were calculated using Rosen's model. The results indicate that the surfactant's contribution is greater than that of the drug both at the interface and in micelles. The short and rigid hydrophobic structure of the drug resists its participation in micelle formation more than in the monolayer, leading to X1
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Self-supported nanoporous cobalt phosphide nanowire arrays: an efficient 3D hydrogen-evolving cathode over the wide range of pH 0-14.
J. Am. Chem. Soc.
PUBLISHED: 05-15-2014
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In this Communication, we report the topotactic fabrication of self-supported nanoporous cobalt phosphide nanowire arrays on carbon cloth (CoP/CC) via low-temperature phosphidation of the corresponding Co(OH)F/CC precursor. The CoP/CC, as a robust integrated 3D hydrogen-evolving cathode, shows a low onset overpotential of 38 mV and a small Tafel slope of 51 mV dec(-1), and it maintains its catalytic activity for at least 80,00 s in acidic media. It needs overpotentials (?) of 67, 100, and 204 mV to attain current densities of 10, 20, and 100 mA cm(-2), respectively. Additionally, this electrode offers excellent catalytic performance and durability under neutral and basic conditions.
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Microwave assisted synthesis, spectroscopic studies and non linear optical properties of bis-chromophores.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 05-06-2014
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Bis chromophores were synthesized by the terephthalaldehyde with (4-nitrophenyl) acetonitrile/(4-flurophenyl) acetonitrile under microwave irradiation. Bis-chromophores were obtained in good to excellent yields. The structures of bis-chromophores were established by FT-IR, (1)H NMR, (13)C NMR, EI-MS and elemental analyses. Physical chemical properties such as singlet absorption, extinction coefficient, stokes shift, oscillator strength and dipole moment, were investigated by UV-Vis and fluorescence spectroscopy measurements. Further we also measured the nonlinear refractive index and nonlinear absorption coefficients of these compounds using the single beam z-scan technique with a cw argon ion laser at 514.5nm at different concentrations in DMSO solvent. The third order nonlinear susceptibility was estimated from these measurements and it shows high nonlinearity. The high negative refractive index makes these compounds suitable for optical limiting application.
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Closely interconnected network of molybdenum phosphide nanoparticles: a highly efficient electrocatalyst for generating hydrogen from water.
Adv. Mater. Weinheim
PUBLISHED: 04-14-2014
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A closely interconnected network of MoP nanoparticles (MoP-CA2) with rich nano-pores, large specific surface area, and high conductivity can function as a highly active non-noble metal catalyst for electrochemically generating hydrogen from acidic water. The network exhibits nearly 100% Faradaic efficiency and needs overpotentials of 125 and 200 mV to attain current densities of 10 and 100 mA cm(-2) , respectively. The catalytic activity is maintained for at least 24 h.
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Carbon nanotubes decorated with CoP nanocrystals: a highly active non-noble-metal nanohybrid electrocatalyst for hydrogen evolution.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 04-10-2014
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The development of effective and inexpensive hydrogen evolution reaction (HER) electrocatalysts for future renewable energy systems is highly desired. The strongly acidic conditions in proton exchange membranes create a need for acid-stable HER catalysts. A nanohybrid that consists of carbon nanotubes decorated with CoP nanocrystals (CoP/CNT) was prepared by the low-temperature phosphidation of a Co3O4/CNT precursor. As a novel non-noble-metal HER catalyst operating in acidic electrolytes, the nanohybrid exhibits an onset overpotential of as low as 40?mV, a Tafel slope of 54?mV?dec(-1), an exchange current density of 0.13?mA?cm(-2), and a Faradaic efficiency of nearly 100?%. This catalyst maintains its catalytic activity for at least 18?hours and only requires overpotentials of 70 and 122?mV to attain current densities of 2 and 10?mA?cm(-2), respectively.
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Carbon nanobelts as a novel sensing platform for fluorescence-enhanced DNA detection.
Analyst
PUBLISHED: 04-05-2014
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The present communication demonstrates for the first time that carbon nanobelts (CNBs) were facilely synthesized on a large scale via pyrolysis of a 1,8-diaminonaphthalene (DAN)-NiCl2·6H2O mixture under Ar followed by acid leaching. We further demonstrate that such CNBs can be used as a novel effective fluorescent sensing platform for DNA. This sensing platform exhibits high selectivity and sensitivity with a detection limit of 5 nM.
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Tandem deprotection-dimerization-macrocyclization route to C(2) symmetric cyclo-tetrapeptides.
Chemistry
PUBLISHED: 04-02-2014
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Dimerization-macrocyclization has been a long-standing problem in the cyclization of peptides since, together with the desired cyclic product, many cyclic oligomers and linear polymers may also be formed during the reaction. Therefore, the development of a process that affords the cyclic dimer predominantly is difficult. A novel and versatile strategy for the synthesis of symmetric cyclo-tetrapeptides by palladium-promoted tandem deprotection/cyclo-dimerization from readily available Cbz-dipeptidoyl benzotriazolides is reported (Cbz=carboxybenzyl).
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Self-supported Cu3P nanowire arrays as an integrated high-performance three-dimensional cathode for generating hydrogen from water.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 03-31-2014
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Searching for inexpensive hydrogen evolution reaction (HER) electrocatalysts with high activity has attracted considerable research interest in the past years. Reported herein is the topotactic fabrication of self-supported Cu3 P nanowire arrays on commercial porous copper foam (Cu3 P NW/CF) from its Cu(OH)2 NW/CF precursor by a low-temperature phosphidation reaction. Remarkably, as an integrated three-dimensional hydrogen-evolving cathode operating in acidic electrolytes, Cu3 P NW/CF maintains its activity for at least 25?hours and exhibits an onset overpotential of 62?mV, a Tafel slope of 67?mV?dec(-1) , and a Faradaic efficiency close to 100?%. Catalytic current density can approach 10?mA?cm(-2) at an overpotential of 143?mV.
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Synthesis of taurine-containing peptides, sulfonopeptides, and N- and O-conjugates.
J. Org. Chem.
PUBLISHED: 03-11-2014
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Taurine-containing water-soluble peptidomimetics were designed and synthesized. N-terminal taurine acylations allowed synthesis of a number of taurine-containing peptides. N-protection of taurine with Cbz and SO2-activation with benzotriazole followed by coupling with various amino esters, dipeptides and nucleophiles provided taurine N- and O-conjugates and sulfonopeptides.
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Ultrathin graphitic C3 N4 nanosheets/graphene composites: efficient organic electrocatalyst for oxygen evolution reaction.
ChemSusChem
PUBLISHED: 02-27-2014
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Graphitic C3 N4 (g-C3 N4 ) is used as a low-cost organic oxygen evolution reaction (OER) electrocatalyst. The integration of ultrathin g-C3 N4 nanosheets with graphene leads to g-C3 N4 /graphene composites with high OER activity and good durability. X-ray photoelectron spectroscopy (XPS) studies suggest that the OER activity results from pyridinic-N-related active sites. This catalyst provides an alternative to OER catalysts based on transition metals.
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Solid fermentation of wheat bran for hydrolytic enzymes production and saccharification content by a local isolate Bacillus megatherium.
BMC Biotechnol.
PUBLISHED: 02-24-2014
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For enzyme production, the costs of solid state fermentation (SSF) techniques were lower and the production higher than submerged cultures. A large number of fungal species was known to grow well on moist substrates, whereas many bacteria were unable to grow under this condition. Therefore, the aim of this study was to isolate a highly efficient strain of Bacillus sp utilizing wheat bran in SSF and optimizing the enzyme production and soluble carbohydrates.
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Nanohybrid Based on Antibiotic Encapsulated Layered Double Hydroxide as a Drug Delivery System.
Appl. Biochem. Biotechnol.
PUBLISHED: 02-19-2014
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Nanohybrid of cefuroxime (CFO) with layered double hydroxide (LDH) has been prepared, and the rate of dissolution and bioavailability of CFO using nanohybrid as a drug delivery system has been broadly studied. The intercalation process was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The CFO contents were found to be 19.0 wt% in the nanohybrid. The release mechanism of CFO was investigated with respect to anion and pH of the dissolution media such as gastric, intestinal and blood simulated media. The effect of pH was evaluated on the release of CFO from nanohybrid, and the dissolution of CFO from the nanohybrid was found to be a slow process at pH 4.0, 6.8, and 7.4. Further the addition of Cl ion and PAM in release media did not affect the release rate of drug at pH 4.0 and 6.8, while at pH 7.4, Cl ion and PAM have significant role on the drug release. At pH 1.2, the release study shows that LDH dissolved in the acidic medium and CFO released in its molecular form. The release behavior suggests two mechanisms that are responsible for the release of CFO from nanohybrid: weathering (dependent on the pH) and ion exchange (highly dependent on the anions). Surface reactions mediated by solid weathering ruled the release in gastric fluid, whereas anion exchange determined CFO release in lysosomal, intestinal, and blood medium. In order to evaluate the drug release mechanism, the released data were fitted by mathematical models describing various kinetic.
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Synthesis, characterization and spectroscopic behavior of novel 2-oxo-1,4-disubstituted-1,2,5,6-tetrahydrobenzo[h]quinoline-3-carbonitrile dyes.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 02-19-2014
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Two synthetic pathways were adopted to synthesize the target 2-oxo-1,4-disubstituted-1,2,5,6-tetrahydro-benzo[h]quinoline-3-carbonitriles. Structure of the synthesized compounds has been characterized based on FT-IR, (1)H NMR, (13)C NMR and elemental analyses. UV-Vis and fluorescence spectroscopy measurements provided that all compounds are good absorbent and fluorescent. Fluorescence polarity study demonstrated that these compounds were sensitive to the polarity of the microenvironment provided by different solvents. In addition, spectroscopic and physicochemical parameters, including singlet absorption, extinction coefficient, Stokes shift, oscillator strength and dipole moment were investigated in order to explore the analytical potential of synthesized compounds.
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Controllable synthesis of SnO2@C yolk-shell nanospheres as a high-performance anode material for lithium ion batteries.
Nanoscale
PUBLISHED: 02-06-2014
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In this work, we report a facile synthesis of uniform SnO2@C yolk-shell nanospheres as high-performance anode materials for lithium ion batteries (LIBs). The yolk-shell structured SnO2@C nanospheres were fabricated through a two-step sol-gel coating process by using tetraethyl orthosilicate (TEOS) and resorcinol-formaldehyde (RF) as precursors, where the silica interlayer not only acts as a template to produce the void space, but also promotes the coating of the RF layer. The synthesis is easy to operate and allows tailoring the carbon shell thickness and void space size. The resultant SnO2@C yolk-shell nanospheres possess a hollow highly crystalline SnO2 core (280-380 nm), tailored carbon shell thickness (15-25 nm) and a large void space size (100-160 nm), a high surface area (?205 m(2) g(-1)), a large pore volume (?0.25 cm(3) g(-1)), as well as a high SnO2 content (77 wt%). When evaluated as an anode of LIBs, the materials manifest superior electrochemical performance with a high lithium storage capability (2190 mA h g(-1) in initial discharge capacity; >950 mA h g(-1) in the first 10 cycles), a good cycling performance and an excellent rate capability.
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Molecular design of donor-acceptor dyes for efficient dye-sensitized solar cells I: a DFT study.
J Mol Model
PUBLISHED: 02-02-2014
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Dye-sensitized solar cells (DSSCs) have drawn great attention as low cost and high performance alternatives to conventional photovoltaic devices. The molecular design presented in this work is based on the use of pyran type dyes as donor based on frontier molecular orbitals (FMO) and theoretical UV-visible spectra in combination with squaraine type dyes as an acceptor. Density functional theory has been used to investigate several derivatives of pyran type dyes for a better dye design based on optimization of absorption, regeneration, and recombination processes in gas phase. The frontier molecular orbital (FMO) of the HOMO and LUMO energy levels plays an important role in the efficiency of DSSCs. These energies contribute to the generation of exciton, charge transfer, dissociation and exciton recombination. The computations of the geometries and electronic structures for the predicted dyes were performed using the B3LYP/6-31+G** level of theory. The FMO energies (EHOMO, ELUMO) of the studied dyes are calculated and analyzed in the terms of the UV-visible absorption spectra, which have been examined using time-dependent density functional theory (TD-DFT) techniques. This study examined absorption properties of pyran based on theoretical UV-visible absorption spectra, with comparisons between TD-DFT using B3LYP, PBE, and TPSSH functionals with 6-31+G (d) and 6-311++G** basis sets. The results provide a valuable guide for the design of donor-acceptor (D-A) dyes with high molar absorptivity and current conversion in DSSCs. The theoretical results indicated 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye (D2-Me) can be effectively used as a donor dye for DSSCs. This dye has a low energy gap by itself and a high energy gap with squaraine acceptor type dye, the design that reduces the recombination and improves the photocurrent generation in solar cell.
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Dual-pore mesoporous carbon@silica composite core-shell nanospheres for multidrug delivery.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 02-01-2014
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Monodispersed mesoporous phenolic polymer nanospheres with uniform diameters were prepared and used as the core for the further growth of core-shell mesoporous nanorattles. The hierarchical mesoporous nanospheres have a uniform diameter of 200?nm and dual-ordered mesopores of 3.1 and 5.8?nm. The hierarchical mesostructure and amphiphilicity of the hydrophobic carbon cores and hydrophilic silica shells lead to distinct benefits in multidrug combination therapy with cisplatin and paclitaxel for the treatment of human ovarian cancer, even drug-resistant strains.
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Humidity and temperature sensing properties of copper oxide-Si-adhesive nanocomposite.
Talanta
PUBLISHED: 01-29-2014
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Smart and professional humidity and temperature sensors have been fabricated by utilizing copper oxide-Si-adhesive composite and pure copper oxide nanosheets. Copper oxide nanosheets are synthesized by low temperature stirring method and characterized by field emission scanning electron microscopy, which reveals that synthesized product is composed of randomly oriented nanosheets, which are grown in high density with an average thickness of~80±10 nm. X-ray diffraction confirms that the grown nanosheets consist of well crystalline monoclinic CuO. X-ray photoelectron spectroscopy and Fourier transform infrared (FTIR) spectroscopy also confirm that the synthesized nanomaterial is pure CuO without any impurity. The fabricated sensors exhibit good temperature sensitivity of -4.0%/°C and -5.2%/°C and humidity sensitivity of -2.9%/%RH and -4.88%/%RH, respectively for copper oxide-Si-adhesive composite and pure copper oxide nanosheets. The average initial resistance of the sensors is equal to 250 M? and 55 M? for the composite and pure copper oxide based sensors, respectively.
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FT-IR, FT-Raman, NMR, UV and quantum chemical studies on monomeric and dimeric conformations of 3,5-dimethyl-4-methoxybenzoic acid.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 01-14-2014
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Extensive spectroscopic investigations along with theoretical quantum chemical studies on 3,5-dimethyl-4-methoxybenzoic acid (DMMBA) have been consummated. The fundamental vibrational transitions were addressed by experimental FT-IR (4000-400cm(-1)) and FT-Raman (4000-10cm(-1)) techniques and density functional calculations at B3LYP/6-311++G(d,p) and B3LYP/6-311++G(df,pd) levels of theory. The (1)H, (13)C and DEPT 135 NMR spectra of studied compound were recorded in deuterated dimethylsulfoxide (DMSO-d6), and compared with computed data obtained by using gauge including atomic orbital (GIAO) method. The electronic absorption spectra in methanol and ethanol solution were evaluated in the range of 200-400nm, and TD-DFT method was chosen for computational study. The spectroscopic and theoretical results were compared to the corresponding properties for monomer and dimer structures for the most stable conformer. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Moreover, the thermodynamic and nonlinear optical (NLO) properties were evaluated.
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Nonlinear dimensionality reduction for visualizing toxicity data: distance-based versus topology-based approaches.
ChemMedChem
PUBLISHED: 01-10-2014
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Over the years, a number of dimensionality reduction techniques have been proposed and used in chemoinformatics to perform nonlinear mappings. In this study, four representatives of nonlinear dimensionality reduction methods related to two different families were analyzed: distance-based approaches (Isomap and Diffusion Maps) and topology-based approaches (Generative Topographic Mapping (GTM) and Laplacian Eigenmaps). The considered methods were applied for the visualization of three toxicity datasets by using four sets of descriptors. Two methods, GTM and Diffusion Maps, were identified as the best approaches, which thus made it impossible to prioritize a single family of the considered dimensionality reduction methods. The intrinsic dimensionality assessment of data was performed by using the Maximum Likelihood Estimation. It was observed that descriptor sets with a higher intrinsic dimensionality contributed maps of lower quality. A new statistical coefficient, which combines two previously known ones, was proposed to automatically rank the maps. Instead of relying on one of the best methods, we propose to automatically generate maps with different parameter values for different descriptor sets. By following this procedure, the maps with the highest values of the introduced statistical coefficient can be automatically selected and used as a starting point for visual inspection by the user.
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Detection and monitoring of toxic chemical at ultra trace level by utilizing doped nanomaterial.
PLoS ONE
PUBLISHED: 01-01-2014
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Composite nanoparticles were synthesized by eco-friendly hydrothermal process and characterized by different spectroscopic techniques. All the spectroscopic techniques suggested the synthesis of well crystalline optically active composite nanoparticles with average diameter of ?30 nm. The synthesized nanoparticles were applied for the development of chemical sensor which was fabricated by coating the nanoparticles on silver electrode for the recognition of phthalimide using simple I-V technique. The developed sensor exhibited high sensitivity (1.7361 µA.mM-1.cm-2), lower detection limit (8.0 µM) and long range of detection (77.0 µM to 0.38 M). Further the resistances of composite nanoparticles based sensor was found to be 2.7 M? which change from 2.7 to 1.7 with change in phthalimide concentration. The major advantages of the designed sensor over existing sensors are its simple technique, low cost, lower detection limit, high sensitivity and long range of detection. It can detect phthalimide even at trace level and sense over wide range of concentrations. Therefore the composite nanoparticals would be a better choice for the fabrication of phthalimide chemical sensor and would be time and cost substituted implement for environmental safety.
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Cellulose-lanthanum hydroxide nanocomposite as a selective marker for detection of toxic copper.
Nanoscale Res Lett
PUBLISHED: 01-01-2014
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In this current report, a simple, reliable, and rapid method based on modifying the cellulose surface by doping it with different percentages of lanthanum hydroxide (i.e., 1% La(OH)3-cellulose (LC), 5% La(OH)3-cellulose (LC2), and 10% La(OH)3-cellulose (LC3)) was proposed as a selective marker for detection of copper (Cu(II)) in aqueous medium. Surface properties of the newly modified cellulose phases were confirmed by Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopic analysis. The effect of pH on the adsorption of modified cellulose phases for Cu(II) was evaluated, and LC3 was found to be the most selective for Cu(II) at pH 6.0. Other parameters, influencing the maximum uptake of Cu(II) on LC3, were also investigated for a deeper mechanistic understanding of the adsorption phenomena. Results showed that the adsorption capacity for Cu(II) was improved by 211% on the LC3 phase as compared to diethylaminoethyl cellulose phase after only 2 h contact time. Adsorption isotherm data established that the adsorption process nature was monolayer with a homogeneous adsorbent surface. Results displayed that the adsorption of Cu(II) onto the LC3 phase obeyed a pseudo-second-order kinetic model. Selectivity studies toward eight metal ions, i.e., Cd(II), Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Ni(II), and Zn(II), were further performed at the optimized pH value. Based on the selectivity study, it was found that Cu(II) is highly selective toward the LC3 phase. Moreover, the efficiency of the proposed method was supported by implementing it to real environmental water samples with adequate results.
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Efficient solar photocatalyst based on cobalt oxide/iron oxide composite nanofibers for the detoxification of organic pollutants.
Nanoscale Res Lett
PUBLISHED: 01-01-2014
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A Co3O4/Fe2O3 composite nanofiber-based solar photocatalyst has been prepared, and its catalytic performance was evaluated by degrading acridine orange (AO) and brilliant cresyl blue (BCB) beneath solar light. The morphological and physiochemical structure of the synthesized solar photocatalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). FESEM indicates that the Co3O4/Fe2O3 composite has fiber-like nanostructures with an average diameter of approximately 20 nm. These nanofibers are made of aggregated nanoparticles having approximately 8.0 nm of average diameter. The optical properties were examined by UV-visible spectrophotometry, and the band gap of the solar photocatalyst was found to be 2.12 eV. The as-grown solar photocatalyst exhibited high catalytic degradation in a short time by applying to degrade AO and BCB. The pH had an effect on the catalytic performance of the as-grown solar photocatalyst, and it was found that the synthesized solar photocatalyst is more efficient at high pH. The kinetics study of both AO and BCB degradation indicates that the as-grown nanocatalyst would be a talented and efficient solar photocatalyst for the removal of hazardous and toxic organic materials.
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Synthesis of silver embedded poly(o-anisidine) molybdophosphate nano hybrid cation-exchanger applicable for membrane electrode.
PLoS ONE
PUBLISHED: 01-01-2014
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Poly(o-anisidine) molybdophosphate was expediently obtained by sol-gel mixing of Poly(o-anisidine) into the inorganic matrices of molybdophosphate, which was allowed to react with silver nitrate to the formation of poly(o-anisidine) molybdophosphate embedded silver nano composite. The composite was characterized by Fourier Transform Infrared Spectroscopy, X-ray powder diffraction, UV-Vis Spectrophotometry, Fluorescence Spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray Spectroscopy and Thermogravimertic Analysis. Ion exchange capacity and distribution studies were carried out to understand the ion-exchange capabilities of the nano composite. On the basis of highest distribution studies, this nano composite cation exchanger was used as preparation of heavy metal ion selective membrane. Membrane was characterized for its performance as porosity and swelling later on was used for the preparation of membrane electrode for Hg(II), having better linear range, wide working pH range (2-4.5) with fast response in the real environment.
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Temperature gradient measurements by using thermoelectric effect in CNTs-silicone adhesive composite.
PLoS ONE
PUBLISHED: 01-01-2014
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This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT) and silicone adhesive. The composite contains CNT and silicon adhesive 1?1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results.
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Synthesis, characterization, electrochemical studies, and in vitro antibacterial activity of novel thiosemicarbazone and its Cu(II), Ni(II), and Co(II) complexes.
ScientificWorldJournal
PUBLISHED: 01-01-2014
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Metal complexes were prepared by the reaction of thiosemicarbazone with CuCl2, NiCl2, CoCl2, Cu(OAc)2, Ni(OAc)2, and Co(OAc)2. The thiosemicarbazone coordinates to metal through the thionic sulfur and the azomethine nitrogen. The thiosemicarbazone was obtained by the thiosemicarbazide with 3-acetyl-2,5-dimethylthiophene. The identities of these compounds were elucidated by IR, (1)H, (13)C-NMR, and GC-MS spectroscopic methods and elemental analyses. The antibacterial activity of these compounds was first tested in vitro by the disc diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) was determined by using chloramphenicol as reference drug. The results showed that compound 1.1 is better inhibitor of both types of tested bacteria as compared to chloramphenicol.
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Nitrophenol chemi-sensor and active solar photocatalyst based on spinel hetaerolite nanoparticles.
PLoS ONE
PUBLISHED: 01-01-2014
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In this contribution, a significant catalyst based on spinel ZnMn2O4 composite nanoparticles has been developed for electro-catalysis of nitrophenol and photo-catalysis of brilliant cresyl blue. ZnMn2O4 composite (hetaerolite) nanoparticles were prepared by easy low temperature hydrothermal procedure and structurally characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and UV-visible spectroscopy which illustrate that the prepared material is optical active and composed of well crystalline body-centered tetragonal nanoparticles with average size of ? 38 ± 10 nm. Hetaerolite nanoparticles were applied for the advancement of a nitrophenol sensor which exhibited high sensitivity (1.500 µAcm(-2) mM(-1)), stability, repeatability and lower limit of detection (20.0 µM) in short response time (10 sec). Moreover, hetaerolite nanoparticles executed high solar photo-catalytic degradation when applied to brilliant cresyl blue under visible light.
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Fabrication of smart chemical sensors based on transition-doped-semiconductor nanostructure materials with µ-chips.
PLoS ONE
PUBLISHED: 01-01-2014
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Transition metal doped semiconductor nanostructure materials (Sb2O3 doped ZnO microflowers, MFs) are deposited onto tiny µ-chip (surface area, ?0.02217 cm(2)) to fabricate a smart chemical sensor for toxic ethanol in phosphate buffer solution (0.1 M PBS). The fabricated chemi-sensor is also exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards ethanol. The calibration plot is linear (r(2)?=?0.9989) over the large ethanol concentration ranges (0.17 mM to 0.85 M). The sensitivity and detection limit is ?5.845 µAcm(-2)mM(-1) and ?0.11±0.02 mM (signal-to-noise ratio, at a SNR of 3) respectively. Here, doped MFs are prepared by a wet-chemical process using reducing agents in alkaline medium, which characterized by UV/vis., FT-IR, Raman, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM) etc. The fabricated ethanol chemical sensor using Sb2O3-ZnO MFs is simple, reliable, low-sample volume (<70.0 µL), easy of integration, high sensitivity, and excellent stability for the fabrication of efficient I-V sensors on ?-chips.
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Sonochemically synthesized MnO2 nanoparticles as electrode material for supercapacitors.
Ultrason Sonochem
PUBLISHED: 10-21-2013
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In this study, manganese oxide (MnO2) nanoparticles were synthesized by sonochemical reduction of KMnO4 using polyethylene glycol (PEG) as a reducing agent as well as structure directing agent under room temperature in short duration of time and characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. A supercapacitor device constructed using the ultrasonically-synthesized MnO2 nanoparticles showed maximum specific capacitance (SC) of 282Fg(-1) in the presence of 1M Ca(NO3)2 as an electrolyte at a current density of 0.5mAcm(-2) in the potential range from 0.0 to 1.0V and about 78% of specific capacitance was retained even after 1000 cycles indicating its high electrochemical stability.
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Ultrathin graphitic carbon nitride nanosheets: a novel peroxidase mimetic, Fe doping-mediated catalytic performance enhancement and application to rapid, highly sensitive optical detection of glucose.
Nanoscale
PUBLISHED: 10-15-2013
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In this article, we demonstrate for the first time that ultrathin graphitic carbon nitride nanosheets (g-C3N4) possess peroxidase activity. Fe doping of the nanosheets leads to peroxidase mimetics with greatly enhanced catalytic performance and the mechanism involved is proposed. We further demonstrate the novel use of such Fe-g-C3N4 as a cheap nanosensor for simple, rapid, highly selective and sensitive optical detection of glucose with a pretty low detection limit of 0.5 ?M.
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Spinel CuCo2O4 nanoparticles supported on N-doped reduced graphene oxide: a highly active and stable hybrid electrocatalyst for the oxygen reduction reaction.
Langmuir
PUBLISHED: 10-15-2013
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In this Letter, for the first time, we demonstrated the preparation of a highly efficient electrocatalyst, spinel CuCo2O4 nanoparticles supported on N-doped reduced graphene oxide (CuCo2O4/N-rGO), for an oxygen reduction reaction (ORR) under alkaline media. The hybrid exhibits higher ORR catalytic activity than CuCo2O4 or N-rGO alone, the physical mixture of CuCo2O4 nanoparticles and N-rGO, and Co3O4/N-rGO. Moreover, such a hybrid affords superior durability to the commercial Pt/C catalyst.
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Ultrasound assisted synthesis of Sn nanoparticles-stabilized reduced graphene oxide nanodiscs.
Ultrason Sonochem
PUBLISHED: 09-05-2013
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Sn nanoparticles-stabilized reduced graphene oxide (RGO) nanodiscs were synthesized by a sonochemical method using SnCl2 and graphene oxide (GO) nanosheets as precursors in a polyol medium. TEM and XPS were used to characterize the Sn-stabilized RGO nanodiscs.
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Ultrathin graphitic carbon nitride nanosheets: a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide and its glucose biosensing application.
Nanoscale
PUBLISHED: 08-12-2013
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In this communication, we demonstrate for the first time that ultrathin graphitic carbon nitride (g-C?N?) nanosheets can serve as a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide. We further demonstrate its application for electrochemical glucose biosensing in both buffer solution and human serum medium with a detection limit of 11 ?M and 45 ?M, respectively.
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An Efficient Approach to the Synthesis of Highly Congested 9,10-Dihydrophenanthrene-2,4-dicarbonitriles and Their Biological Evaluation as Antimicrobial Agents.
Molecules
PUBLISHED: 08-08-2013
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An efficient and novel method for the synthesis in moderate to good yield (72%-84%) of a series of 3-amino-1-substituted-9,10-dihydrophenanthrene-2,4-dicarbonitriles 1-5 via one-pot multi-component reactions of aldehydes, malononitrile, 1-tetralone and ammonium acetate has been delineated. Cyclocondensation attempts of aminocyanophenanthrene derivatives 1, 2, 4 and 5 with acetic anhydride in the presence of conc. H2SO4 failed and instead the diacetylamino derivatives 10-13 were obtained. All prepared compounds were structurally elucidated by various spectroscopic methods and X-ray crystallography. N,N-diacetylamino-derivatives of phenanthrene have shown good antimicrobial activity.
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Two-dimensional hybrid mesoporous Fe2O3-graphene nanostructures: a highly active and reusable peroxidase mimetic toward rapid, highly sensitive optical detection of glucose.
Biosens Bioelectron
PUBLISHED: 08-07-2013
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In this article, for the first time, two-dimensional hybrid mesoporous Fe2O3-graphene (mFe2O3-G) nanostructures were developed as a peroxidase mimetic with catalytic activities superior to those of mFe2O3, G, and previously reported Fe-based peroxidase mimetics. The high-surface-area mFe2O3 not only offers a large number of catalytically active sites, but also facilitates the diffusion of 3,3,5,5-tetramethylbenzidine (TMB) and H2O2 toward G surface. On the other hand, G is ?-rich and thus favors the adsorption and enrichment of TMB within these pores. These synergistic effects lead to highly improved catalytic performances. Based on these findings, a simple, rapid, and highly sensitive and selective optical detector of glucose has been developed and demonstrated in buffer solution with a pretty low detection limit of 0.5 ?M. In addition, this nanosensor is reusable and can also be used for glucose detection in diluted serum.
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Green material: ecological importance of imperative and sensitive chemi-sensor based on Ag/Ag2O3/ZnO composite nanorods.
Nanoscale Res Lett
PUBLISHED: 07-23-2013
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In this report, we illustrate a simple, easy, and low-temperature growth of Ag/Ag2O3/ZnO composite nanorods with high purity and crystallinity. The composite nanorods were structurally characterized by field emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy which confirmed that synthesized product have rod-like morphology having an average cross section of approximately 300 nm. Nanorods are made of silver, silver oxide, and zinc oxide and are optically active having absorption band at 375 nm. The composite nanorods exhibited high sensitivity (1.5823 ?A.cm-2.mM-1) and lower limit of detection (0.5 ?M) when applied for the recognition of phenyl hydrazine utilizing I-V technique. Thus, Ag/Ag2O3/ZnO composite nanorods can be utilized as a redox mediator for the development of highly proficient phenyl hydrazine sensor.
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An assessment of zinc oxide nanosheets as a selective adsorbent for cadmium.
Nanoscale Res Lett
PUBLISHED: 07-23-2013
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Zinc oxide nanosheet is assessed as a selective adsorbent for the detection and adsorption of cadmium using simple eco-friendly extraction method. Pure zinc oxide nanosheet powders were characterized using field emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The zinc oxide nanosheets were applied to different metal ions, including Cd(II), Cu(II), Hg(II), La(III), Mn(II), Pb(II), Pd(II), and Y(III). Zinc oxide nanosheets were found to be selective for cadmium among these metal ions when determined by inductively coupled plasma-optical emission spectrometry. Moreover, adsorption isotherm data provided that the adsorption process was mainly monolayer on zinc oxide nanosheets.
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Au-nanoparticle-loaded graphitic carbon nitride nanosheets: green photocatalytic synthesis and application toward the degradation of organic pollutants.
ACS Appl Mater Interfaces
PUBLISHED: 07-22-2013
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Au nanoparticles (AuNPs) were loaded on graphitic carbon nitride (g-C3N4) nanosheets prepared by ultrasonication-assisted liquid exfoliation of bulk g-C3N4 via green photoreduction of Au(III) under visible light irradiation using g-C3N4 as an effective photocatalyst. The nanohybrids show superior photocatalytic activities for the decomposition of methyl orange under visible-light irradiation to bulk g-C3N4, g-C3N4 nanosheets, and AuNP/bulk g-C3N4 hybrids.
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A novel pH sensitive water soluble fluorescent nanomicellar sensor for potential biomedical applications.
Bioorg. Med. Chem.
PUBLISHED: 07-05-2013
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Herein we report on the synthesis and sensor activity of a novel pH sensitive probe designed as highly water-soluble fluorescent micelles by grafting of 1,8-naphthalimide-rhodamine bichromophoric FRET system (RNI) to the PMMA block of a well-defined amphiphilic diblock copolymer-poly(methyl methacrylate)-b-poly(methacrylic acid) (PMMA48-b-PMAA27). The RNI-PMMA48-b-PMAA27 adduct is capable of self-assembling into micelles with a hydrophobic PMMA core, containing the anchored fluorescent probe, and a hydrophilic shell composed of PMAA block. Novel fluorescent micelles are able to serve as a highly sensitive pH probe in water and to internalize successfully HeLa and HEK cells. Furthermore, they showed cell specificity and significantly higher photostability than that of a pure organic dye label such as BODIPY. The valuable properties of the newly prepared fluorescent micelles indicate the high potential of the probe for future biological and biomedical applications.
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2-Chloro-6-(2,3-di-chloro-benzene-sulfonamido)-benzoic acid.
Acta Crystallogr Sect E Struct Rep Online
PUBLISHED: 06-01-2013
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In the title compound, C13H8Cl3NO4S, the aromatic rings are oriented at a dihedral angle of 68.94?(1)° and the mol-ecule adopts a V-shape. An intra-molecular N-H?O inter-action generates a six-membered S(6) ring motif. In the crystal, pairs of O-H?O hydrogen bonds involving the carb-oxy group link the mol-ecules into inversion dimers with an R 2 (2)(8) motif. N-H?O and non-classical C-H?O inter-actions connect the mol-ecules, forming sheets propagating in (100).
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Ultrathin graphitic carbon nitride nanosheet: a highly efficient fluorosensor for rapid, ultrasensitive detection of Cu(2+).
Anal. Chem.
PUBLISHED: 05-17-2013
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A highly efficient fluorosensor based on ultrathin graphitic carbon nitride (g-C?N?) nanosheets for Cu(2+) was developed. In the absence of metal ions, the nanosheets exhibit high fluorescence; the strong coordination of the Lewis basic sites on them to metal ions, however, causes fluorescence quenching via photoinduced electron transfer leading to the qualitative and semiquantitative detection of metal ions. This fluorosensor exhibits high selectivity toward Cu(2+). The whole detection process can be completed within 10 min with a detection limit as low as 0.5 nM. The use of test paper enables the naked-eye detection of Cu(2+) with a detection limit of 0.1 nmol. The practical use of this sensor for Cu(2+) determination in real water samples was also demonstrated.
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5-Acetyl-3-(5-phenyl-1H-pyrazol-3-yl)-1,3,4-thia-diazol-2(3H)-one monohydrate.
Acta Crystallogr Sect E Struct Rep Online
PUBLISHED: 05-01-2013
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In the title hydrate, C13H10N4O2S·H2O, the dihedral angles between the central pyrazole ring and its pendant phenyl and thia-diazole rings are 9.93?(8) and 4.56?(7)°, respectively. In the crystal, the components are linked by N-H?O, O-H?N and O-H?O hydrogen bonds, generating [100] chains incorporating R 4 (4)(10) loops. A weak C-H?O inter-action helps to consolidate the packing.
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An experimental and theoretical investigation of Acenaphthene-5-boronic acid: conformational study, NBO and NLO analysis, molecular structure and FT-IR, FT-Raman, NMR and UV spectra.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 04-29-2013
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The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400cm(-1) and 4000-10cm(-1), respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H?O hydrogen bonding have been discussed. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability ???, its components and associated properties such as average polarizability and anisotropy of the polarizability (? and ??) of AN-5-BA was calculated using the finite-field approach.
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Synthesis and biological evaluation of some novel tetrahydroquinolines as anticancer and antimicrobial agents.
J Enzyme Inhib Med Chem
PUBLISHED: 04-22-2013
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Abstract This study reports the synthesis of a series of new 2-amino-3-cyano-8-methyl-4-substituted-5,6,7,8-tetrahydroquinolines along with some derived fused-ring systems. Ten compounds have shown remarkable cytotoxic activity against human colon carcinoma HT29, hepatocellular carcinoma HepG2 and Caucasian breast adenocarcinoma MCF7 cell lines. Six compounds showed considerable broad-spectrum cytotoxic activity among which two proved to be the most active derivatives. Likewise, seven compounds from the series were found to exhibit significant antimicrobial activity and three of them proved to be the most active candidates. Two alkylthio-pyrimido quinolines are suggested as possible antimicrobial and anticancer candidates in the present series.
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Investigation of spectroscopic behaviors of newly synthesized (2E)-3-(3,4-dimethoxyphenyl)-1-(2,5-dimethylthiophen-3-yl)prop-2-en-1-one (DDTP) dye.
J Fluoresc
PUBLISHED: 04-18-2013
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This study introduced spectroscopic properties, physicochemical parameters, and polarity and photostability behaviors of a newly prepared chalcone dye. The chalcone dye, (2E)-3-(3,4-Dimethoxyphenyl)-1-(2,5-dimethylthiophen-3-yl)prop-2-en-1-one (DDTP), was synthesized by the reaction of 3,4-dimethoxybenzaldehyde with 3-acetyl-2,5-dimethythiophene. Results of FT-IR, (1)H-NMR, (13)C-NMR and elemental analysis were in conformity with chemical structure of newly prepared DDTP. Data of thermal gravimetric analysis revealed that DDTP has good thermal stability. Increases in fluorescence intensities of DDTP with cetyltrimethyl ammonium bromide (CTAB) were observed. In comparison of fluorescence intensities for DDTP with CTAB, reductions in fluorescence intensities for DDTP with sodium dodecyl sulphate (SDS) were observed under the same experimental and instrumental conditions. Moreover, Benesi-Hildebrand method was applied to determine stoichiometric ratios and association constants of DDTP with CTAB and SDS. The stoichiometric ratio and association constant obtained from Stern-Volmer plot strongly supported those obtained from Benesi-Hildebrand plot of DDTP with SDS. Physicochemical parameters, such as, singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of DDTP were also estimated. Fluorescence steady-state measurements ultimately displayed that DDTP has a high photostability against photobleaching. Fluorescence polarity study revealed that DDTP was sensitive to the polarity of the microenvironment provided by different solvents.
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Acetone sensor based on solvothermally prepared ZnO doped with Co3O4 nanorods.
Mikrochim Acta
PUBLISHED: 03-14-2013
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This paper describes a reliable and sensitive method for sensing dissolved acetone using doped nanomaterials. Large-scale synthesis of ZnO nanorods (NRs) doped with Co3O4 was accomplished by a solvothermal method at low temperature. The doped NRs were characterized in terms of their morphological, structural, and optical properties by using field-emission scanning electron microscopy coupled with energy-dispersive system, UV-Vis., Fourier transform IR, X-ray diffraction, and Xray photoelectron spectroscopy. The calcinated (at 400 °C) doped NRs are shown to be an attractive semiconductor nanomaterial for detecting acetone in aqueous solution using silver electrodes. The sensor exhibits excellent sensitivity, stability and reproducibility. The calibration plot is linear over a large concentration range (66.8 ?M to 0.133 mM), displays high sensitivity (~3.58 ?A cm(-2) mM(-1)) and a low detection limit (~14.7?±?0.2 ?M; at SNR of 3). FigureThe present study describes a simple, reliable, accurate, sensitive, and cost effective method for the detection of acetone using solvothermally prepared semiconductor co-doped nanomaterials.
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Single-particle spectroscopy on large SAPO-34 crystals at work: methanol-to-olefin versus ethanol-to-olefin processes.
Chemistry
PUBLISHED: 02-11-2013
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The formation of hydrocarbon pool (HCP) species during methanol-to-olefin (MTO) and ethanol-to-olefin (ETO) processes have been studied on individual micron-sized SAPO-34 crystals with a combination of in situ UV/Vis, confocal fluorescence, and synchrotron-based IR microspectroscopic techniques. With in situ UV/Vis microspectroscopy, the intensity changes of the ?=400?nm absorption band, ascribed to polyalkylated benzene (PAB) carbocations, have been monitored and fitted with a first-order kinetics at low reaction temperatures. The calculated activation energy (Ea ) for MTO, approximately 98?kJ?mol(-1) , shows a strong correlation with the theoretical values for the methylation of aromatics. This provides evidence that methylation reactions are the rate-determining steps for the formation of PAB. In contrast for ETO, the Ea value is approximately 60?kJ?mol(-1) , which is comparable to the Ea values for the condensation of light olefins into aromatics. Confocal fluorescence microscopy demonstrates that during MTO the formation of the initial HCP species are concentrated in the outer rim of the SAPO-34 crystal when the reaction temperature is at 600?K or lower, whereas larger HCP species are gradually formed inwards the crystal at higher temperatures. In the case of ETO, the observed egg-white distribution of HCP at 509?K suggests that the ETO process is kinetically controlled, whereas the square-shaped HCP distribution at 650?K is indicative of a diffusion-controlled process. Finally, synchrotron-based IR microspectroscopy revealed a higher degree of alkylation for aromatics for MTO as compared to ETO, whereas high reaction temperatures favor dealkylation processes for both the MTO and ETO processes.
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Quantum chemical study of the donor-bridge-acceptor triphenylamine based sensitizers.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 02-08-2013
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Quantum chemical calculations were carried to investigate the electron coupling, electron injection, electronic and photophysical properties of 2-cyano-5-(4-(phenyl(4-vinylphenyl)amino)phenyl) penta-2,4-dienoic acid (TC4) and its derivatives. Geometries have been optimized by using density functional theory at B3LYP/6-31G(**) level of theory. The highest occupied molecular orbitals (HOMOs) are delocalized on triphenylamine (TPA) units while lowest unoccupied molecular orbitals LUMOs are localized on anchoring groups. The mono-methyl is more significant to lowering the energy gap than di and tri-methyl substituted ones. The HOMOs of the dyes are below the redox couple and LUMOs are above the conduction band of TiO2. We have explained the recombination barrier on the basis of distortion and coplanarity. The excitation energies have been computed by time dependent density functional theory at PCM-CAM-B3LYP/6-31G(**) level of theory. Enhanced bridge is encouraging to promote the electron injection, electronic coupling constant and light harvesting efficiency. Generally, electron injection, electronic coupling constant and light harvesting efficiency of new designed sensitizers are higher than TC4. This revealed that new materials would be efficient photosensitizers.
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Chemo-sensors development based on low-dimensional codoped Mn2O3-ZnO nanoparticles using flat-silver electrodes.
Chem Cent J
PUBLISHED: 01-18-2013
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Semiconductor doped nanostructure materials have attained considerable attention owing to their electronic, opto-electronic, para-magnetic, photo-catalysis, electro-chemical, mechanical behaviors and their potential applications in different research areas. Doped nanomaterials might be a promising owing to their high-specific surface-area, low-resistances, high-catalytic activity, attractive electro-chemical and optical properties. Nanomaterials are also scientifically significant transition metal-doped nanostructure materials owing to their extraordinary mechanical, optical, electrical, electronic, thermal, and magnetic characteristics. Recently, it has gained significant interest in manganese oxide doped-semiconductor materials in order to develop their physico-chemical behaviors and extend their efficient applications. It has not only investigated the basic of magnetism, but also has huge potential in scientific features such as magnetic materials, bio- & chemi-sensors, photo-catalysts, and absorbent nanomaterials.
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Synthesis of Ag nanoparticle-decorated 2,4,6-tris(2-pyridyl)-1,3,5-triazine nanobelts and their application for H2O2 and glucose detection.
Analyst
PUBLISHED: 12-19-2011
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The present paper reports on the first preparation of 2,4,6-tris(2-pyridyl)-1,3,5-triazine nanobelts (TPTNBs) by adjusting the pH value of the solution and the subsequent synthesis of Ag nanoparticle (AgNP)-decorated TPTNBs (AgNP-TPTNBs) by mixing an aqueous AgNO(3) solution with preformed TPTNBs without use of any external reducing agent. It is found that the resultant AgNP-TPTNBs exhibit notable catalytic performance for H(2)O(2) reduction. A glucose biosensor was fabricated by immobilizing glucose oxidase (GOD) onto a AgNP-TPTNBs-modified glassy carbon electrode (GCE) for glucose detection. The constructed glucose sensor has a wide linear response range from 3 mM to 20 mM (r: 0.999) with a detection limit of 190 ?M. It is further shown that this glucose biosensor can be used for glucose detection in human blood serum.
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3-cyano-8-methyl-2-oxo-1,4-disubstituted-1,2,5,6,7,8-hexahydroquinolines: synthesis and biological evaluation as antimicrobial and cytotoxic agents.
J Enzyme Inhib Med Chem
PUBLISHED: 12-03-2011
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The synthesis, in vitro antimicrobial and cytotoxic activities of some novel hexahydroquinolines supported with various pharmacophores are described. The results revealed that 18 compounds displayed pronounced activity against Staphylococcus aureus and Escherichia coli bacteria beside a moderate antifungal activity. Compound 25 is the most active candidate with equipotency to ampicillin against S. aureus, E. coli and Pseudomonas aeruginosa, together with an obvious antifungal activity. Additionally, 12 compounds showed remarkable cytotoxic efficiency against human colon carcinoma HT29, hepatocellular carcinoma Hep-G2 and Caucasian breast adenocarcinoma MCF7 cell lines. Among these, the analogs 22 and 25 proved to be the most active cytotoxic members. Collectively, the results would suggest that compounds 22 and 25 could be considered as possible dual antimicrobial-anticancer agents.
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