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Chemical reactions

Simone Cristoni, Guglielmo Dusi, Paolo Brambilla, Adriana Albini, Matteo Conti, Maura Brambilla, Antonino Bruno, Francesca Digaudio, Luca Ferlin, Valeria Tazzari, Silvia Mengozzi, Simone Barera, Carlos Salier, Tommaso Trenti, Marco Cantu, Luigi Rossi Bernardi, Douglas M Noonan
Electrospray Ionization (EI) and Collision Induced Dissociation tandem mass spectrometry (CID-MS/MS) are usually employed to obtain compound identification through a mass spectra match. Different algorithms have been developed for this purpose (for example the NIST match algorithm). These approaches compare the tandem mass spectra (MS/MS) of the unknown analyte with the MS/MS spectra of known compounds inserted in a database. The compounds are usually identified on the basis of spectral match value associated with a probability of recognition...
October 24, 2016: Journal of Mass Spectrometry: JMS
K Anand, C Tiloke, A Phulukdaree, B Ranjan, A Chuturgoon, S Singh, R M Gengan
The biosynthesis of nanostructured biopalladium nanoparticles (PdNPs) from an aqueous solution of crystalline palladium acetate is reported. For the synthesised PdNPs in solution, an agroforest biomass waste petal of Moringa oleifera derived bis-phthalate was used as natural reducing and biocapping agents. Continuous absorption in the UV region and subsequent brown colour change confirmed the formation of PdNPs. A strong surface plasmon peak for PdNPs occurred at 460nm. PdNPs were characterized by SEM with EDX, FTIR, TEM and DLS...
September 29, 2016: Journal of Photochemistry and Photobiology. B, Biology
Xiaolan Zeng, Jing Chen, Ruijuan Qu, Xiaoxue Pan, Zunyao Wang
The atmospheric chemical reactions of some polyfluorinated dibenzofurans (PFDFs) and polychlorinated dibenzofurans (PCDFs), initiated by OH radical, were investigated by performing theoretical calculations using density functional theory (DFT) and B3LYP/6-311++G(2df,p) method. The obtained results indicate that OH addition reactions of PFDFs and PCDFs occurring at C1∼4 and CA sites are thermodynamic spontaneous changes and the branching ratio of the PF(C)DF-OH adducts is decided primarily by kinetic factor...
October 21, 2016: Chemosphere
Imran Ullah, Krishnendu Bhattacharyya, Sharidan Shafie, Ilyas Khan
Numerical results are presented for the effect of first order chemical reaction and thermal radiation on mixed convection flow of Casson fluid in the presence of magnetic field. The flow is generated due to unsteady nonlinearly stretching sheet placed inside a porous medium. Convective conditions on wall temperature and wall concentration are also employed in the investigation. The governing partial differential equations are converted to ordinary differential equations using suitable transformations and then solved numerically via Keller-box method...
2016: PloS One
Amir Zahir, Chesahna Kindred, Brunhilde Blömeke, Carsten Goebel, Anthony A Gaspari
BACKGROUND: Allergic contact dermatitis after exposure to p-phenylenediamine (PPD)-containing hair dye products is a common and important clinical problem. Because there is a high rate of cross-elicitation of allergic contact dermatitis to other important hair dye products (such as p-toluene diamine and other aminophenol hair dyes) in PPD-allergic patients, safer alternative dyes with excellent hair coloring options are needed. OBJECTIVE: This study aimed to study tolerance to Me-PPD in a PPD-allergic cohort...
October 21, 2016: Dermatitis
Stavros Karakalos, Yun-Fei Xu, Fairoja Cheenicode Kabeer, Wei Chen, Juan Carlos F Rodriguez-Reyes, Alexandre Tkatchenko, Efthimios Kaxiras, Robert J Madix, Cynthia M Friend
Enhancing the selectivity of catalytic processes has potential for substantially increasing the sustainability of chemical production. Herein, we establish relationships between reaction selectivity and molecular structure for a homologous series of key intermediates for oxidative coupling of alcohols on gold using a combination of experiment and theory. We establish a scale of binding for molecules with different alkyl structures and chain lengths and thereby demonstrate the critical nature of non-covalent van der Waals interactions in determining the selectivity by modulating the stability of key reaction intermediates bound to the surface...
October 24, 2016: Journal of the American Chemical Society
Jie Yin, Qiaohui Fan, Yuxuan Li, Fangyi Cheng, Panpan Zhou, Pinxian Xi, Shouheng Sun
We report a facile nitrogenation/exfoliation process to prepare hybrid Ni-C-N nanosheets. These nanosheets are < 2 nm thin, chemically stable, and metallically conductive. They serve as a robust catalyst for the hydrogen evolution reaction in 0.5 M H2SO4, or 1.0 M KOH or 1.0 M PBS (pH = 7). For example, they catalyze the HER in 0.5 M H2SO4 at an onset potential of 34.7 mV, an overpotential of 60.9 mV (at j = 10 mA cm(-2)) and with remarkable long-term stability (~10% current drop after 70 h testing period)...
October 24, 2016: Journal of the American Chemical Society
Ryan Kenny, Fei Liu
Cooperativity is essential to proficient catalysis, and designing biomimetic, cooperative catalysis is a major avenue to finding new and efficient chemical reactions with practical applications. One challenge in designed cooperative catalysis is to access high catalytic proficiency (large enhancement in both rate and enantioselectivity) as seen in biocatalysis. Here described is an approach of developing and investigating trifunctional organocatalysts with three distinct catalytic functionalities, in order to understand how cooperativity could be organized for enantioselective activation that confers the observed proficiency in a tandem Michael-aldol-proton transfer elimination model reaction...
October 24, 2016: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Christopher Goldring, Daniel J Antoine, Frank Bonner, Jonathan Crozier, Chris Denning, Robert J Fontana, Neil A Hanley, David C Hay, Magnus Ingelman-Sundberg, Satu Juhila, Neil Kitteringham, Beatriz Silva-Lima, Alan Norris, Chris Pridgeon, James A Ross, Rowena Sison Young, Danilo Tagle, Belen Tornesi, Bob van de Water, Richard J Weaver, Fang Zhang, B Kevin Park
Current preclinical drug testing does not predict some forms of adverse drug reactions in humans. Efforts at improving predictability of drug-induced tissue injury in humans include using stem cell technology to generate human cells for screening for adverse effects of drugs in humans. The advent of induced pluripotent stem cells means that it may ultimately be possible to develop personalised toxicology to determine inter-individual susceptibility to adverse drug reactions. However, the complexity of idiosyncratic drug-induced liver injury (DILI) means that no current single cell model, whether of primary liver tissue origin, from liver cell lines, or derived from stem cells, adequately emulates what is believed to occur during human DILI...
October 24, 2016: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
Tae Soup Shim, Zaki G Estephan, Zhaoxia Qian, Jacob H Prosser, Su Yeon Lee, David M Chenoweth, Daeyeon Lee, So-Jung Park, John C Crocker
Active materials that respond to physical and chemical stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices. In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals...
October 24, 2016: Nature Nanotechnology
Lucie Pinasseau, Arnaud Verbaere, Maryline Roques, Emmanuelle Meudec, Anna Vallverdú-Queralt, Nancy Terrier, Jean-Claude Boulet, Véronique Cheynier, Nicolas Sommerer
A rapid, sensitive, and selective analysis method using ultra high performance liquid chromatography coupled with triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) has been developed for the characterization and quantification of grape skin flavan-3-ols after acid-catalysed depolymerization in the presence of phloroglucinol (phloroglucinolysis). The compound detection being based on specific MS transitions in Multiple Reaction Monitoring (MRM) mode, this fast gradient robust method allows analysis of constitutive units of grape skin proanthocyanidins, including some present in trace amounts, in a single injection, with a throughput of 6 samples per hour...
October 21, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
So Won Youn, Eun Mi Lee
A highly efficient and facile metal-free, one-pot reaction has been developed to afford diversely substituted N-arylbenzimidazoles through chemoselective in situ generation of N,N'-diarylamidines from arenediazonium salts, nitriles, and free anilines. The advantages of this protocol consist of the operationally easy and simple one-pot procedure under metal-free and mild conditions, the direct use of inexpensive and commercially available chemicals, and thus, a cost-effective and greener process.
October 24, 2016: Organic Letters
Zhenqin Wu, Huimin Bi, Sichen Pan, Lingyi Meng, Xin Sheng Zhao
Fluorescence correlation spectroscopy (FCS) is a powerful tool to investigate molecular diffusion and relaxations, which may be utilized to study many problems, such as molecular size and aggregation, chemical reaction, molecular transportation and motion, and various kinds of physical and chemical relaxations. This paper focuses on a problem related to using the relaxation term to study a reaction. If two species with different fluorescence photon emission efficiencies are connected by a reaction, the kinetic and equilibrium properties will be manifested in the relaxation term of the FCS curve...
October 24, 2016: Journal of Physical Chemistry. B
Wan-Yi Li, Xia Li, Steffen Jockusch, Han Wang, Bolei Xu, Yajing Wu, William Gang Tsui, Hai-Lung Dai, V Faye McNeill, Yi Rao
Photoactivated reactions of organic species in atmospheric aerosol particles are a potentially significant source of secondary organic aerosol material (SOA). Despite recent progress, the dominant chemical mechanisms and rates of these reactions remain largely unknown. In this work, we characterize the photo-physical properties and photochemical reaction mechanisms of imidazole-2-carboxaldehyde (IC) in aqueous solution, alone and in the presence of isoprene. IC has been shown previously in laboratory studies to participate in photoactivated chemistry in aerosols, and is a known in-particle reaction product of glyoxal...
October 24, 2016: Journal of Physical Chemistry. A
Maura Marinozzi, Fabrizio Pertusati, Michaela Serpi
The compounds characterized by the presence of a λ(5)-phosphorus functionality at the α-position with respect to the diazo moiety, here referred to as λ(5)-phosphorus-containing α-diazo compounds (PCDCs), represent a vast class of extremely versatile reagents in organic chemistry and are particularly useful in the preparation of phosphonate- and phosphinoxide-functionalized molecules. Indeed, thanks to the high reactivity of the diazo moiety, PCDCs can be induced to undergo a wide variety of chemical transformations...
October 24, 2016: Chemical Reviews
Shaodong Zhou, Jilai Li, Maria Schlangen, Helmut Schwarz
The thermal gas-phase reactions of the closed-shell metal-oxide cluster [Al2 TaO5 ](+) with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Mechanistic aspects have been addressed to reveal the origins of the efficient addition process which results in activating the C-H bond of methane. The [Al2 TaO5 ](+) /CH4 couple has been compared with several other systems reported previously, and the electronic origins of their rather distinct performances are discussed...
October 24, 2016: Angewandte Chemie
Lode De Munck, Carlos Vila, M Carmen Muñoz, José R Pedro
A catalytic highly enantioselective aza-Reformatsky reaction with cyclic aldimines and ketimines for the synthesis of chiral β-amino esters with good yields and excellent enantioselectivities is reported. A readily available diaryl prolinol is used as a chiral ligand, ZnMe2 as a zinc source and ethyl iodoacetate as reagent in the presence of air atmosphere. The reaction with cyclic ketimines generates a quaternary stereocenter with excellent levels of enantioselectivity. Furthermore, five-membered N-sulfonyl ketimines were used as electrophiles with good enantiomeric excesses, under the optimized reaction conditions...
October 24, 2016: Chemistry: a European Journal
Susanna Piluso, Al Halifa Soultan, Jennifer Patterson
BACKGROUND: Polymer-based systems are attractive in drug delivery and regenerative medicine due to the possibility of tailoring their properties and functions to a specific application. METHODS: The present review provides several examples of molecularly engineered polymer systems, including stimuli responsive polymers and supramolecular polymers. RESULTS: The advent of controlled polymerization techniques has enabled the preparation of polymers with controlled molecular weight and well-defined architecture...
October 21, 2016: Current Pharmaceutical Design
Tetsuro Kusamoto, Shun Kimura, Yasuyo Ogino, Chie Ohde, Hiroshi Nishihara
The open-shell luminescent (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl (PyBTM) radical contains a nitrogen atom that behaves as a stimulus-responsive site. Chemical modification at this nitrogen atom, such as coordination of B(C6 F5 )3 or methylation, shifts the emission maximum to the low-energy region and increases the reduction potential. The emission colour may be regulated by the reversible Lewis acid-base reaction between B(C6 F5 )3 and PyBTM. Comparison of the optical and electrochemical properties of the radicals with the electronic structures calculated by density functional theory has indicated that the chemical modification decreased the energy level of the β-singly occupied molecular orbital, a key orbital in determining the optical and electrochemical properties of such systems...
October 24, 2016: Chemistry: a European Journal
Christian Hänsel, Semih Afyon, Jennifer L M Rupp
All-solid-state Li-ion batteries based on lithium garnets give new prospects for safer battery operations avoiding liquids, and could enable the integration of high energy density electrode materials. Herein, we critically investigate the structural and chemical stability of the high voltage cathode material, LiMn1.5Ni0.5O4, based on the solid lithium garnet electrolyte LLZO (c-Li6.4Ga0.2La3Zr2O12) for all-solid Li-ion batteries. We manufacture battery cells based on nano-grained synthesized LLZO and composite cathodes (LiMn1...
October 24, 2016: Nanoscale
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