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Full-Text Articles in Physical Sciences and Mathematics

Vibrational Spectroscopy Of Intermediates Of C-H Bond Activation By Transition Metal Oxide Cations, Gokhan Altinay Sep 2010

Vibrational Spectroscopy Of Intermediates Of C-H Bond Activation By Transition Metal Oxide Cations, Gokhan Altinay

Open Access Dissertations

Direct, efficient oxidation of alkanes is a long-standing goal of catalysis. Gas phase FeO+ can convert methane to methanol and benzene to phenol under thermal conditions. Two key intermediates of these reactions are the [HO-Fe-R]+ insertion intermediate and Fe+(ROH) (R=CH3 or C6H5) exit channel complex. This work describes measurements of the vibrational spectra of these intermediates and electronic structure theory calculations of the potential energy surfaces for the reactions. They help to characterize the mechanism for these reactions. Chapter 1 describes previous studies of methane-to-methanol and benzene-to-phenol conversion by gas-phase transition metal oxide cations. Spectra of gas-phase reaction intermediates are …


Charge And Energy Transport In Single Quantum Dot/Organic Hybrid Nanostructures, Kevin Thomas Early Sep 2010

Charge And Energy Transport In Single Quantum Dot/Organic Hybrid Nanostructures, Kevin Thomas Early

Open Access Dissertations

Hybrid quantum dot /organic semiconductor systems are of great interest in optoelectronic and photovoltaic applications, because they combine the robust and tunable optical properties of inorganic semiconductors with the processability of organic thin films. In particular, cadmium selenide (CdSe) quantum dots coordinated with oligo-(phenylene vinylene) ligands have displayed a number of hybrid optical properties that make them particularly well-suited to these applications. When probed on an individual particle level, these so-called CdSe-OPV nanostructures display a number of surprising photophysical characteristics, including strong quenching of fluorescence from coordinating ligands, enhanced emission from the CdSe quantum dot core, suppression of fluorescence intermittency, …


Field Portable Methods For The Determination Of Arsenic In Environmental Samples, James Kalman Kearns Sep 2010

Field Portable Methods For The Determination Of Arsenic In Environmental Samples, James Kalman Kearns

Open Access Dissertations

Arsenic contamination of the environment is a worldwide health hazard. This research project focused on four areas: development and testing of low cost, field portable devices capable of measuring levels of arsenic at 10 μg L-1 or less; specific chemical techniques for such testing; creation of educational tools and techniques to allow operators who lack advanced chemistry training to perform accurate testing; and the determination and use of a biomarker in DNA as a cancer predictor in individuals exposed to environmental arsenic. The analytical techniques explored include: (1) the Gutzeit method of arsenic determination though arsine gas production, which was …


Time Resolved Single Molecule Spectroscopy Of Semiconductor Quantum Dot/Conjugated Organic Hybrid Nanostructures, Michael Yemoh Odoi Sep 2010

Time Resolved Single Molecule Spectroscopy Of Semiconductor Quantum Dot/Conjugated Organic Hybrid Nanostructures, Michael Yemoh Odoi

Open Access Dissertations

Single molecule studies on CdSe quantum dots functionalized with oligo-phenylene vinylene ligands (CdSe-OPV) provide evidence of strong electronic communication that facilitate charge and energy transport between the OPV ligands and the CdSe quantum dot core. This electronic interaction greatly modify, the photoluminescence properties of both bulk and single CdSe-OPV nanostructure thin film samples. Size-correlated wide-field fluorescence imaging show that blinking suppression in single CdSe-OPV is linked to the degree of OPV coverage (inferred from AFM height scans) on the quantum dot surface. The effect of the complex electronic environment presented by photoexcited OPV ligands on the excited state property of …


Structural Characterization Of The Pre-Amyloid Oligomers Of Β-2-Microglobulin Using Covalent Labeling And Mass Spectrometry, Vanessa Leah Castillo Mendoza Sep 2010

Structural Characterization Of The Pre-Amyloid Oligomers Of Β-2-Microglobulin Using Covalent Labeling And Mass Spectrometry, Vanessa Leah Castillo Mendoza

Open Access Dissertations

The initial steps involved in the assembly of normally soluble proteins into amyloid fibrils remain unclear, yet over 20 human diseases are associated with proteins that aggregate in this manner. Protein surface modification is a potential means of mapping the interaction sites in early oligomers that precede amyloid formation. This dissertation focuses on the use of covalent labeling combined with mass spectrometry to elucidate the structural features of Cu(II)-induced β-2-microglobulin (β2m) amyloid formation. An improved covalent modification and MS-based approach for protein surface mapping has been developed to address the need for a reliable approach that ensures protein structural integrity …


Role Of Surface Charge Density In Nanoparticle-Templated Assembly Of Bromovirus Protein Cages, Mc Daniel, Ib Tsvetkova, Zt Quinkert, A Murali, M De, Vm Rotello, Cc Kao, B Dragnea Jun 2010

Role Of Surface Charge Density In Nanoparticle-Templated Assembly Of Bromovirus Protein Cages, Mc Daniel, Ib Tsvetkova, Zt Quinkert, A Murali, M De, Vm Rotello, Cc Kao, B Dragnea

Vincent Rotello

Self-assembling icosahedral protein cages have potencially useful physical and chemical characteristics for a variety of nanotechnology applications, ranging from therapeutic or diagnostic vectors to building blocks for hierarchical materials. For application-specific functional control of protein cage assemblies, a deeper understanding of the interaction between the protein cage and its payload is necessary. Protein-cage encapsulated nanoparticles, with their well-defined surface chemistry, allow for systematic control over key parameters of encapsulation such as the surface charge, hydrophobicity, and size. Independent control over these variables allows experimental testing of different assembly mechanism models. Previous studies done with Brome mosaic virus capsids and negatively …


Effect Of Nanoparticle Surface Charge At The Plasma Membrane And Beyond, Rr Arvizo, Or Miranda, Ma Thompson, Cm Pabelick, R Bhattacharya, Jd Robertson, Vm Rotello, Ys Prakash, P Mukherjee Jun 2010

Effect Of Nanoparticle Surface Charge At The Plasma Membrane And Beyond, Rr Arvizo, Or Miranda, Ma Thompson, Cm Pabelick, R Bhattacharya, Jd Robertson, Vm Rotello, Ys Prakash, P Mukherjee

Vincent Rotello

Herein, we demonstrate that the surface charge of gold nanoparticles (AuNPs) plays a critical role in modulating membrane potential of different malignant and nonmalignant cell types and subsequent downstream intracellular events. The findings presented here describe a novel mechanism for cell-nanoparticle interactions and AuNP uptake: modulation of membrane potential and its effect on intracellular events. These studies will help understand the biology of cell-nanoparticle interactions and facilitate the engineering of nanoparticles for specific intracellular targets.


Gold Nanoparticle Self-Assembly Promoted By A Non-Covalent, Charge-Complemented Coiled-Coil Peptide, D Ernenwein, P Ghosh, V Rotello, J Chmielewski Jun 2010

Gold Nanoparticle Self-Assembly Promoted By A Non-Covalent, Charge-Complemented Coiled-Coil Peptide, D Ernenwein, P Ghosh, V Rotello, J Chmielewski

Vincent Rotello

Non-covalent interactions between cationic gold nanoparticles and an anionic coiled-coil peptide were harnessed for coiled-coil mediated self-assembly of gold nanoparticles (GNPs)


Quaternary Structure Of Chemoreceptors In Active Signaling Complexes Differs From Crystal Structure Of Isolated Fragments: Evidence From Solid-State Nmr, Daniel John Fowler May 2010

Quaternary Structure Of Chemoreceptors In Active Signaling Complexes Differs From Crystal Structure Of Isolated Fragments: Evidence From Solid-State Nmr, Daniel John Fowler

Open Access Dissertations

The receptor dimers that mediate bacterial chemotaxis form high-order signaling complexes with CheW and the kinase CheA. From the packing arrangement in two crystal structures of different receptor cytoplasmic fragments, two different models have been proposed for receptor signaling arrays: the trimers-of-dimers and hedgerow models. We identified an interdimer distance that differs substantially in the two models, labeled the atoms defining this distance through isotopic enrichment, and measured it with 13C-19F REDOR. This was done in two types of receptor samples: first, isolated bacterial membranes containing overexpressed, intact receptor, and second, soluble receptor fragments reconstituted into kinase-active signaling complexes. In …


Enzyme-Amplified Array Sensing Of Proteins In Solution And In Biofluids, Or Miranda, Ht Chen, Cc You, De Mortenson, Xc Yang, Uhf Bunz, Vm Rotello Mar 2010

Enzyme-Amplified Array Sensing Of Proteins In Solution And In Biofluids, Or Miranda, Ht Chen, Cc You, De Mortenson, Xc Yang, Uhf Bunz, Vm Rotello

Vincent Rotello

We have developed an enzyme−nanoparticle sensor array where the sensitivity is amplified through enzymatic catalysis. In this approach cationic gold nanoparticles are electrostatically bound to an enzyme (β-galactosidase, β-Gal), inhibiting enzyme activity. Analyte proteins release the β-Gal, restoring activity and providing an amplified readout of the binding event. Using this strategy we have been able to identify proteins in buffer at a concentration of 1 nM, substantially lower than current strategies for array-based protein sensing. Moreover, we have obtained identical sensitivity in studies where the proteins are spiked into the complex protein matrix provided by desalted human urine (1.5 μM …


Recognition Mediated Encapsulation And Isolation Of Flavin-Polymer Conjugates Using Dendritic Guest Moieties, C Subramani, G Yesilbag, Bj Jordan, Xn Li, A Khorasani, G Cooke, A Sanyal, Vm Rotello Feb 2010

Recognition Mediated Encapsulation And Isolation Of Flavin-Polymer Conjugates Using Dendritic Guest Moieties, C Subramani, G Yesilbag, Bj Jordan, Xn Li, A Khorasani, G Cooke, A Sanyal, Vm Rotello

Vincent Rotello

Diaminopyridine dendritic scaffolds encapsulate polymeric flavin via non-covalent interactions and demonstrate isolation of the redox moiety.


Chemically Directed Immobilization Of Nanoparticles Onto Gold Substrates For Orthogonal Assembly Using Dithiocarbamate Bond Formation, Mh Park, Xx Duan, Y Ofir, B Creran, D Patra, Xy Ling, J Huskens, Vm Rotello Feb 2010

Chemically Directed Immobilization Of Nanoparticles Onto Gold Substrates For Orthogonal Assembly Using Dithiocarbamate Bond Formation, Mh Park, Xx Duan, Y Ofir, B Creran, D Patra, Xy Ling, J Huskens, Vm Rotello

Vincent Rotello

Dithiocarbamate-mediated bond formation combined with soft lithography was used for the selective immobilization of amine-functionalized silica nanoparticles on gold substrates. The available amine groups on the upper surface of the immobilized silica nanoparticles were further utilized for postdeposition of additional materials including particles, dyes, and biomolecules. The robustness of dithiocarbamate-mediated immobilization enables orthogonal assembly on surfaces via selective removal of the masking thiol ligands using iodine vapor etching followed by further functionalization.


Hyperbranched Conjugated Polymers: Postfunctionalization, C Kub, J Tolosa, Aj Zucchero, Pl Mcgrier, C Subramani, A Khorasani, Vm Rotello, Uhf Bunz Feb 2010

Hyperbranched Conjugated Polymers: Postfunctionalization, C Kub, J Tolosa, Aj Zucchero, Pl Mcgrier, C Subramani, A Khorasani, Vm Rotello, Uhf Bunz

Vincent Rotello

Out on a limb: Sonogashira coupling of a suitable AB(2) monomer containing two iodine and one alkyne group forms a hyperbranched conjugated polymer that is studded with iodine end groups (see picture: I purple). These iodine groups are a perfect handle for convenient, efficient, and high-yielding post-functionalization to access hyperbranched, fluorescent poly(phenyleneethynylene)s.


Intracellular Delivery Of A Membrane-Impermeable Enzyme In Active Form Using Functionalized Gold Nanoparticles, P Ghosh, Xc Yang, R Arvizo, Zj Zhu, Ss Agasti, Zh Mo, Vm Rotello Feb 2010

Intracellular Delivery Of A Membrane-Impermeable Enzyme In Active Form Using Functionalized Gold Nanoparticles, P Ghosh, Xc Yang, R Arvizo, Zj Zhu, Ss Agasti, Zh Mo, Vm Rotello

Vincent Rotello

Gold nanoparticles were coated with a short peptide to promote intracellular delivery of membrane-impermeable proteins. Through microscopy and enzyme assays, we demonstrated the particles were able to transport functional enzymes into a variety of cell lines. Significantly, the transported proteins were able to escape from endosomes. Moreover, these particles showed no apparent cytotoxicity.


Structural And Mechanistic Studies Of Alpha-Galactosidase A And Pharmacological Chaperones, Abigail Ida Guce Feb 2010

Structural And Mechanistic Studies Of Alpha-Galactosidase A And Pharmacological Chaperones, Abigail Ida Guce

Open Access Dissertations

Human α-galactosidase (α-GAL; EC 3.2.1.22) is a lysosomal enzyme that hydrolyzes of terminal alpha-linked galactosyl residue of glycosphingolipids. Deficiencies in α-GAL leads to Fabry disease, which is characterized by the build-up of globotriaosylceramide and other neutral substrates in cells, ultimately leading to a multi-systemic organ failure in patients. Hundreds of distinct mutations have been found in the α-GAL gene of Fabry disease patients. One current treatment for Fabry disease is Enzyme Replacement Therapy (ERT), which restores the missing α-GAL function. An alternative treatment, called Pharmacological Chaperone Therapy (PCT), utilizes a small molecule substrate analogue, 1-deoxygalactonojirimycin (DGJ). In order to better …


My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum Jan 2010

My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum

Emeritus Faculty Author Gallery

This document describes Otto Vogl's work in Italy. From 1975, Vogl served for 3 years as the Chairman of the Scientific Advisory Committee to the President Italo Trapasso of the Plastic Materials Company of Montedison SA, Milan, Italy. He was assigned to restructure the research activities and to organize the Research Division. He was responsible for the appointment of DiDrusco as the Vice President of Research and Paolo Galli as the Director of Research at the company’s facilities in Ferrara. Within a year of Vogl’s reorganization of the research organization the high yield catalyst for the polymerization of propylene was …


Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl Jan 2010

Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl

Emeritus Faculty Author Gallery

No abstract provided.


Proposal Narrative, Morton Sternheim, Stephan Schneider Jan 2010

Proposal Narrative, Morton Sternheim, Stephan Schneider

STEM Digital

No abstract provided.


Sorption Of Bovine Serum Albumin On Nano And Bulk Oxide Particles, Lei Song Jan 2010

Sorption Of Bovine Serum Albumin On Nano And Bulk Oxide Particles, Lei Song

Masters Theses 1911 - February 2014

Manufactured oxide nanoparticles (NPs) have large production and widespread applications, which will inevitably enter the environment. NPs can interact with proteins in living beings due to the fact that NPs can transport into blood or across cell membranes into cells. Conformational change of protein molecules after sorption on oxide NPs has been reported. Therefore, it is important to understand the adsorption mechanism of protein onto oxide NPs surfaces. Although few works have reported protein adsorption behaviors, a general systematic comparison of the effects of particle size and surface groups on protein adsorption by widely studied NPs still needs to be …


Nitrogen Dioxide In The Urban Forest: Exposure And Uptake, Tanner B. Harris Jan 2010

Nitrogen Dioxide In The Urban Forest: Exposure And Uptake, Tanner B. Harris

Masters Theses 1911 - February 2014

Nitrogen dioxide (NO2) levels were measured inside and adjacent to canopies of urban trees in Springfield, MA, over two growing seasons. Nitrogen dioxide levels were consistently and significantly higher inside tree canopies compared to levels outside. During the second growing season, ozone (O3), temperature, and relative humidity (RH) were also measured using samplers co-located with the NO2 samplers. Ozone levels were significantly lower inside the canopy whereas temperatures were higher inside the canopy, and RH was not different between inner and outer canopy locations. The results corroborate theoretical models predicting elevated NO2 and depressed O3 levels inside tree canopies based …


Detecting Atmospheric Carbon Dioxide With Btb, Stephan Schneider Jan 2010

Detecting Atmospheric Carbon Dioxide With Btb, Stephan Schneider

IPY STEM Polar Connections

A study of the concentration of carbon dioxide gas in air samples requires an understanding of effective sampling techniques, the use of pH indicators, an understanding of chemical reactions that result on the formation of acidic compounds, and an understanding of the chemical processes that contribute to the composition and characteristics of Earth’s atmosphere.


Phytoprotective Influence Of Bacteria On Growth And Cadmium Accumulation In The Aquatic Plant Lemna Minor, Lisa M Stout, Elena N Dodova, Julian Tyson, Klaus Nusslein Jan 2010

Phytoprotective Influence Of Bacteria On Growth And Cadmium Accumulation In The Aquatic Plant Lemna Minor, Lisa M Stout, Elena N Dodova, Julian Tyson, Klaus Nusslein

Chemistry Department Faculty Publication Series

No abstract provided.


Mid-Gap Electronic States In Zn1-Xmnxo., C. A. Johnson, Kevin R. Kittilstved, T. C. Kaspar, T. C. Droubay, S. A. Chambers, G. M. Salley, D. R. Gamelin Jan 2010

Mid-Gap Electronic States In Zn1-Xmnxo., C. A. Johnson, Kevin R. Kittilstved, T. C. Kaspar, T. C. Droubay, S. A. Chambers, G. M. Salley, D. R. Gamelin

Kevin R. Kittilstved

Electronic absorption, magnetic circular dichroism (MCD), photoconductivity, and valence-band x-ray photoelectron (XPS) spectroscopic measurements were performed on epitaxial Zn1−xMnxO films to investigate the origin of the mid-gap band that appears upon introduction of Mn2+ into the ZnO lattice. Absorption and MCD spectroscopies reveal Mn2+-related intensity at energies below the first excitonic transition of ZnO, tailing well into the visible energy region, with an onset at ∼2.2 eV. Photoconductivity measurements show that excitation into this visible band generates mobile charge carriers, consistent with assignment as a Mn2+/3+ photoionization transition. XPS measurements reveal the presence of occupied Mn2+ levels just above the …


Array-Based Sensing Of Normal, Cancerous, And Metastatic Cells Using Conjugated Fluorescent Polymers, A Bajaj, Or Miranda, R Phillips, Ib Kim, Dj Jerry, Uhf Bunz, Vm Rotello Jan 2010

Array-Based Sensing Of Normal, Cancerous, And Metastatic Cells Using Conjugated Fluorescent Polymers, A Bajaj, Or Miranda, R Phillips, Ib Kim, Dj Jerry, Uhf Bunz, Vm Rotello

Vincent Rotello

A family of conjugated fluorescent polymers was used to create an array for cell sensing. Fluorescent conjugated polymers with pendant charged residues provided multivalent interactions with cell membranes, allowing the detection of subtle differences between different cell types on the basis of cell surface features. Highly reproducible characteristic patterns were obtained from different cell types as well as from isogenic cell lines, enabling the identification of the cell type as well differentiating between normal, cancerous, and metastatic isogenic cell types with high accuracy.


My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum Jan 2010

My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum

Otto Vogl

This document describes Otto Vogl's work in Italy. From 1975, Vogl served for 3 years as the Chairman of the Scientific Advisory Committee to the President Italo Trapasso of the Plastic Materials Company of Montedison SA, Milan, Italy. He was assigned to restructure the research activities and to organize the Research Division. He was responsible for the appointment of DiDrusco as the Vice President of Research and Paolo Galli as the Director of Research at the company’s facilities in Ferrara. Within a year of Vogl’s reorganization of the research organization the high yield catalyst for the polymerization of propylene was …


Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl Jan 2010

Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl

Otto Vogl

No abstract provided.