Chemistry

Engineering of Flexible Loops in Enzymes
ACS CatalysisDOI: 10.1021/cs500325p


Generation of M@C2n+ (M = Ca, Sr, Ba, 2n = 50-230) by Laser Ablation of Graphene
Metallofullerene ions of M @ C 2 n + (M=Ca, Sr, Ba, 2n=50 – 230) were generated by laser ablation of graphene and corresponding metal salts using a commercial MALDI source without any modification. Large monometallofullerene ions up to Ba@ C 272 + , and di-metallofullerene ions were observed in the mass spectra. The endohedral structures are confirmed by on resonance co...
Formation of Fulvene in the Reaction of C2H with 1,3-Butadiene
Products formed in the reaction of C2H radicals with 1,3-butadiene at 4Torr and 298K are probed using photoionization time-of-flight mass spectrometry. The reaction takes place in a slow-flow reactor, and products are ionized by tunable vacuum-ultraviolet light from the Advanced Light Source. The principal reaction channel involves addition of the radical to one of the unsaturated sites of 1,3-...


Development and Potential Theranostic Applications of a Self-Assembled Hybrid of Magnetic Nanoparticle Clusters with Polysaccharide Nanogels
A new organic–inorganic hybrid was generated by self-assembly of nanosized polymer hydrogels (nanogels) and Fe3O4 nanoparticles (NPs) for potential biomedical applications. By using the tetrahydrofuran (THF) injection method, hydrophobized Fe3O4 NPs were complexed through hydrophobic interactions with amphiphilic polysaccharide nanogels. The obtained hybrid showed high colloidal stability and...
Surface-Enhanced Raman Scattering (SERS) Substrate Based on Large-Area Well-Defined Gold Nanoparticle Arrays with High SERS Uniformity and Stability
A fabrication process that combines an ultrathin alumina membrane (UTAM) surface nanopatterning technique and a physical vapor deposition method has been designed for realizing well-defined Au nanoparticle arrays for sensitive, uniform, and stable surface-enhanced Raman scattering (SERS)-active substrates. High Raman signals are obtained by adjusting the structural parameters of the metallic na...


5-(1H-Tetrazolyl)-2-Hydroxy-Tetrazole: A Selective 2N-Monoxidation of Bis(1H-Tetrazole)
Sodium 5-cyanotetrazolate sesquihydrate (1) is prepared from sodium azide and two equivalents of sodium cyanide under acidic conditions. 1 is then N-oxidized with Oxone to sodium 5-cyanotetrazolate monohydrate . Compound 2 is treated with sodium azide and a Lewis acid to form 5-(1H-tetrazolyl)-2-hydroxytetrazole monohydrate . Compound 3 can be deprotonated twice by various bases to give ion...
Enhanced Penetration of Silver Nanocomposite Assemblies into Dentine Using Iontophoresis: Toward the Treatment of Dental Caries
A strategy to prevent and treat tooth decay, which utilises electrophoretic movement of charged, antibacterial silver nanocomposite structures to infiltrate human dentine to target bacteria contained within the dentine tubules, has been developed and evaluated. Scanning electron microscopy and energy-dispersive X-ray spectroscopy have confirmed high affinity of the nanocomposite structures for ...

Investigation into the structural composition of hydroalcoholic solutions as basis for the development of multiple suppression pulse sequences for NMR measurement of alcoholic beverages
An eight-fold suppression pulse sequence was recently developed to improve sensitivity in 1H NMR measurements of alcoholic beverages [Magn. Res. Chem. 2011 (49): 734–739]. To ensure that only one combined hydroxyl peak from water and ethanol appears in the spectrum, adjustment to a certain range of ethanol concentrations was required. To explain this observation, the structure of water–etha...
NMR of solutes in nematic and smectic A liquid crystals: the anisotropic intermolecular potential
Orientational order parameters determined from 1H NMR spectroscopy of solutes in liquid crystals that form both nematic and smectic A phases are used to determine the solute smectic A order parameters and the smectic–nematic coupling term. For the analysis, it is necessary to know the nematic part of the potential in the smectic A phase: various ways of extrapolating parameters from the nemat...

Dynamic NMR study of cyclic derivatives of pyridoxine
A series of pyridoxine derivatives was investigated by 1H and 2D nuclear overhauser enhancement spectroscopy (NOESY) NMR. The free energies of activation for the pyridyl-oxygen rotation of the 2,4-dinitrophenyl ether of the seven-membered acetals of pyridoxine were measured by dynamic NMR. A conformational exchange between the chair and twist forms of the seven-membered acetal ring was confirme...
Conformational problem of alkanes in liquid crystals by NMR spectroscopy: a mini-review
Recent discoveries of the role of alkane flexibility in determining liquid-crystal behaviour are surveyed. With the impetus for understanding the alkane conformational problem established, recent model dependent 1H NMR work on the topic will be reviewed where progress is made but the need to circumvent models eventually becomes evident. A closer look at the rigid basic units of alkanes will pro...

Polyamide hydrolysis accelerated by small weak organic acids
It is well known that acidity, pH, of a solution accelerates the hydrolysis of soluble amides. Here we describe the unexpected result that weak small organic acids at low concentrations hydrolyze a polyamide at rates approximately twice that of a water HCl solution of the same pH. The effect of three small organic acids in dilute solutions, acetic, propanoic, and butanoic was studied. It is obs...
The in vitro and in vivo degradation behavior of poly (trimethylene carbonate-co-ε-caprolactone) implants
The degradation behavior of P(TMC-co-CL) in different compositions was investigated via subcutaneous implantation in vivo. To clarify the role of enzymes in the degradation behavior of the copolymers, hydrolytic and enzymatic degradation were also performed. The mass loss, changes in molecular weight and polydispersity, as well as the variation in composition were monitored with degradation. Th...
Mechanisms of structural organizational processes as revealed by real time mechano optical behavior of PET film during sequential biaxial stretching
The main focus of this research is to identify the structural mechanisms that are responsible for changes observed in various stages of coupled mechano-optical (stress and strain optical) relationships as they are influenced by the deformation mode, level and rate. This involves in situ real time studies of the true-stress-strain-birefringence of sequential biaxially stretched PET films using a...
Electrical and mechanical percolation in graphene-latex nanocomposites
Conductive composites based on few layer graphene are of primary interests. In this work latex based composites were produced leading to a specific cellular morphology. Highly conductive graphene-based composite materials have been produced through a solvent-free procedure. Both the mechanical and conductivity behaviors were successfully described using a percolation approach that confirms the ...