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- <p>Aerogels<br />Crosslinking (Polymerization)<br />Nuclear magnetic resonance<br />Relaxation (Nuclear physics)</p> (1)
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Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay
C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay
Chemistry Faculty Research & Creative Works
The C1(naphthyl)-H, C2(naphthyl)-H, C3(naphthyl)-H and C8(naphthyl)-H bonds of the naphthyl group present in a group of naphthylazo-2'-hydroxyarenes (H 2L) have been activated by [Rh(PPh 3) 3Cl] in a toluene medium. Here the cyclometallation is accompanied by metal centered oxidation [Rh(i)?Rh(iii)]. All the resulting cyclometallates [Rh(PPh 3) 2(L)Cl] (2-5) have been isolated in a pure form. The characterization of the cyclometallates [Rh(PPh 3) 2(L)Cl] have been done on the basis of spectral (IR, UV-vis, and FAB mass) data. The structures of the representative cyclometallates 2a, 3a, 4a, 4b and 5b have been determined by …
A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak
A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak
Chemistry Faculty Research & Creative Works
Various quaternary CuInxGa1-xS2 (0≤x≤1) chalcopyrite nanoparticles have been prepared from molecular single-source precursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility. Depending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This method has been used to generate up to 5g of nanoparticles and up to 150g from multiple batch reactions with excellent reproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown high reproducibility in nanoparticle size, composition, and bandgap.
Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann
Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann
Chemistry Faculty Research & Creative Works
Thin films of FeSb3 were characterized by electronic transport, magnetometry, x-ray diffraction, 57Fe and 121Sb nuclear inelastic scattering, and 57Fe Mössbauer spectroscopy. Resistivity and magnetometry measurements reveal semiconducting behavior with a 16.3(4) meV band gap and an effective paramagnetic moment of 0.57(6) B, respectively. A systematic comparison of the lattice dynamics with CoSb3 and EuFe 4Sb12 reveals that the Fe4Sb12 framework is softer than the Co4Sb12 framework, and that the observed softening and the associated lowering of the lattice thermal conductivity in the RFe4Sb12 filled skutterudites …
Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier
Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier
Chemistry Faculty Research & Creative Works
The synthesis of the title salt, [Ag(C 6H 7N 4) 2](NO 3) 3, was carried out employing a 1:2 molar ratio of 2,2'-biimidazole and silver nitrate respectively. The cation has crystallographically-imposed C2 symmetry with the metal atom in an almost linear coordination environment [N - Ag - N = 177.01 (17)°]. The crystal structure displays N - H⋯O and C - H⋯O hydrogen-bonding interactions.
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Chemistry Faculty Research & Creative Works
The magnetic, electronic, and Mössbauer spectral properties of Fe 2L(µ-OAc)2ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm-1 for an …
Relaxation Imaging To Characterize Lightweight Polymer-Crosslinked Aerogels, Emmalou T. Satterfield
Relaxation Imaging To Characterize Lightweight Polymer-Crosslinked Aerogels, Emmalou T. Satterfield
Masters Theses
"Silica aerogels are three-dimensional assemblies of silica nanoparticles with extremely low densities. In some instances, the internal void volume is more than 90% of the total volume. The highly porous structure of the aerogels leads to attractive properties for thermal and noise insulation, due to very low thermal conductivity and very high acoustic impedance. The strength of silica aerogels has been substantially improved by casting a thin conformal polymer coating over the entire internal porous surfaces of the nanostructure. The coating reinforces the interparticle connections without significantly compromising the internal void space. To analyze and compare the properties of several …
Development Of A Versatile Man-Portable Obscurant Aerosol Generator: Characterization Of Aerosols In Laboratory And Field Environments, Robert William Schaub
Development Of A Versatile Man-Portable Obscurant Aerosol Generator: Characterization Of Aerosols In Laboratory And Field Environments, Robert William Schaub
Doctoral Dissertations
"The objective of research presented in this dissertation was to develop a readily deployable and environmentally benign obscurant system operating with a single liquid for the visible and near infrared regions. To achieve this objective, research efforts were directed in two areas: i. Evaluating suitable biogenic oils to replace the United States Army's "Fog Oil" as the obscurant fluid. ii. Design, fabrication and validation of a prototype man-portable / vehicle mountable modular obscurant aerosol generator. Petroleum middle distillate - "Fog Oil" has been the material of choice for wide area obscuration for several decades. Large quantities (thousands gallons) of the …
Enhanced Photorefractivity In A Polymeric Composite Photosensitized With Carbon Nanotubes Grafted To A Photoconductive Polymer, Naveen Kumar Lingam, Sonali Kalghatgi, Jeffrey G. Winiarz
Enhanced Photorefractivity In A Polymeric Composite Photosensitized With Carbon Nanotubes Grafted To A Photoconductive Polymer, Naveen Kumar Lingam, Sonali Kalghatgi, Jeffrey G. Winiarz
Chemistry Faculty Research & Creative Works
We report on the photosensitization of photorefractive (PR) polymeric composites through the inclusion of multiwalled and singlewalled carbon nanotubes (CNTs), respectively, having poly(N -vinyl carbazole) (PVK) grafted to their surfaces. The PR nature of the holographic gratings was confirmed via the asymmetric exchange of energy in a two-beam-coupling (TBC) geometry, yielding TBC gain coefficients approaching 80 cm-1. In addition, in degenerate-four-wave- mixing experiments the prepared composites exhibited diffraction efficiencies as high as 60% and overmodulation voltages as low as ∼40 V/μm. These notable figures of merit indicate that the grafting of the PVK polymer to the various CNTs …
Synthesis And Binding Studies Of Peptide Mimetics, Anion Receptors, And Kinase Inhibitors, Nanditha G. Nair
Synthesis And Binding Studies Of Peptide Mimetics, Anion Receptors, And Kinase Inhibitors, Nanditha G. Nair
Doctoral Dissertations
"A series of novel purine-based fluoroaryl triazoles were synthesized and assayed for their neuroprotective effects of hippocampal slice culture exposed to amyloid beta (Aß) oligomers. A monofluorinated triazole has been identified which has comparable neuroprotective effect as that of flavopiridol and roscovitine against the Aß induced neurotoxicity. Carnosine and histidine are biologically interesting antioxidants. In order to probe whether they exert their antioxidant effect through metal ion chelation, the Cu(ll) ion chelating abilities of these compounds were measured by UV-vis spectroscopy. Amyloid beta, the major component of senile plaques in Alzheimer's disease, is known to complex transition metal ions through …
Investigation Of Occurrence, Elimination And Degradation Of Pharmaceutical And Personal Care Products In Drinking Water Using Liquid Chromatography-Tandem Mass Spectrometry, Chuan Wang
Doctoral Dissertations
"Pharmaceutical and personal care products have benefited humans and animals around the world. However, their presence in natural and treated water system as emerging contaminates may have potentially adverse effects on the aquatic environment and cause development of bacterial resistance. In this research project, a comprehensive liquid chromatography tandem mass spectrometry method has been developed and validated for the analysis of sixteen pharmaceutical compounds using solid phase extraction. Treated and untreated water samples collected across Missouri from water treatment facilities were analyzed to access the distribution of sixteen pharmaceutical compounds in both winter and summer seasons. The results of the …
Part-I Characterization Of Phorbol Ester; The Predominant Toxic Component Of Jathropha Curcas And Development Of An Efficient Process For The Detoxification Of Jathropha Curcas Meal Part-Ii Quantification Of 2-Hydroxy-4-(Methylthio) Butanoic Acid And Pantothenic Acid In Bovine Serum And Sea Water Matrices, Balaji Viswanathan
Doctoral Dissertations
"Jatropha curcas is has often been touted as the most sustainable biofuel source. Jatropha curcas is a drought resistant perennial plant belonging to the Euphorbiaceae family. Interest in this plant as a biofuel source is related to high lipid (triglyceride) content of its seeds. However, economics of jatropha as a biofuel source has been marred by the toxicity of the oil and its protein rich meal. As a result of high toxicity the protein rich meal is used only as a very low or no economic value organic fertilizer. Economic return from jatropha can be dramatically enhanced through development of …
Aerogels And Films Through Free Radical Polymerization, Anand G. Sadekar
Aerogels And Films Through Free Radical Polymerization, Anand G. Sadekar
Doctoral Dissertations
"Aerogels are porous lightweight materials, unique among all solids in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. The penalty for those exceptional properties is fragility. That issue has been addressed by bridging covalently (crosslinking) the elementary nanoscopic building blocks of silica aerogels with polymers. To streamline the crosslinking process we synthesized a bidentate free radical initiator (Si-AIBN) that gets attached on the skeletal nanoparticles and induces crosslinking by surface initiated polymerization (SIP). Here, we extend the scope of Si-AIBN in two directions: (a) we demonstrate extremely adhering, covalently attached polymer coatings on oxidized …
Epitaxial Electrodeposition Of Metal Oxide Films And Superlattices Which Exhibit Resistance Switching, Rakesh V. Gudavarthy
Epitaxial Electrodeposition Of Metal Oxide Films And Superlattices Which Exhibit Resistance Switching, Rakesh V. Gudavarthy
Doctoral Dissertations
"This dissertation presents an investigation of the electrodeposition of metal oxide films and superlattices on conducting polycrystalline and single crystal substrates. In the first part of the study, electrodeposition of magnetite (Fe₃O₄) films and superlattices in the magnetite/zinc ferrite system which exhibit resistance switching is studied. Paper I reports the electrodeposition of superlattices in the magnetite/zinc ferrite system and shows that only superlattices exhibit multistate resistance switching. In paper II, simple polycrystalline magnetite films electrodeposited on stainless steel crystals exhibit multistate resistance switching which can be tuned by controlling the composition of the films. Paper II describes the epitaxial electrodeposition …
Preliminary Model Development Of Metal Complexation Of Polyester Derivatives Of 2,2'-Biimidazole, Shelonda Rena Taylor Finch
Preliminary Model Development Of Metal Complexation Of Polyester Derivatives Of 2,2'-Biimidazole, Shelonda Rena Taylor Finch
Doctoral Dissertations
"The objective of this study was to develop a chemical model for metal ion complex formation by a macroligand system with multi-metal binding sites using 2,2'-biimidazole as the starting molecule of the ligand system. Prior studies in this laboratory guided the selection of diesters and hydroxyethyl derivatives of 2,2'-biimidazole as model monomers. In addition, metal ion complexation studies with 2,2'-biimidazole derivatives were conducted. As a result, crystal structures of 1,1'-di(methylpropionato)-2,2-biimidazole, 2,2'-bis(1H-imidazolium) dinitrate and silver 2,2'-bis(1H-imidazolium) trinitrate, were reported. The crystal structures indicated a dependence upon the binding ability of the protonated 2,2'-biimidazole and counter ions. transesterification of the diesters and …
Interfacial Effects On Dielectric Properties Of Polymer-Particle Nanocomposites, Sasidhar Siddabattuni
Interfacial Effects On Dielectric Properties Of Polymer-Particle Nanocomposites, Sasidhar Siddabattuni
Doctoral Dissertations
"Dielectric materials that are capable of efficiently storing large amounts of electrical energy are desirable for many electronic and power devices. Since the electrical energy density in a dielectric material is limited to εVb²/2, where ε is the dielectric permittivity of the material and Vb is the breakdown strength, increased permittivity and breakdown strength are required for large energy storage density. Interfacial effects can influence the dielectric properties, especially dielectric breakdown resistance in polymer-particle nanocomposites. Several functional organophosphates were used to modify the surface of titania and barium titanate nanofiller particles in order to achieve covalent interface …
One Pot Synthesis Of Metal, Carbides And Polymeric Aerogels, Naveen K. Chandrasekaran
One Pot Synthesis Of Metal, Carbides And Polymeric Aerogels, Naveen K. Chandrasekaran
Doctoral Dissertations
"Ultra-low density, three-dimensional assemblies of nanoparticles are referred to as aerogels, and typically are derived from supercritical fluid (SCF) drying of wet-gels. Aerogels are generally fragile materials, but that issue has been addressed successfully by X-aerogels, in which the inorganic nanoparticle framework plays the role of the template for the accumulation of polymer that connects covalently and crosslinks the nanoparticles. The resulting materials can be 300x stronger than the native network, for a nominal increase in density by a factor of 3x. Since the exceptional mechanical properties of X-aerogels are traced to the conformal polymer coating, it was reasonable to …