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Two-photon Photoemission of Organic Semiconductor Molecules on Ag(111)

Description: Angle- and time-resolved two-photon photoemission (2PPE) was used to study systems of organic semiconductors on Ag(111). The 2PPE studies focused on electronic behavior specific to interfaces and ultrathin films. Electron time dynamics and band dispersions were characterized for ultrathin films of a prototypical n-type planar aromatic hydrocarbon, PTCDA, and representatives from a family of p-type oligothiophenes.In PTCDA, electronic behavior was correlated with film morphology and growth modes… more
Date: May 15, 2008
Creator: Yang, Aram & Yang, Aram
Partner: UNT Libraries Government Documents Department
open access

A Cloudy Quark Bag Model of S, P, and D wave interactions for the coupled channel antikaon-nucleon system

Description: The Cloudy Quark Bag Model is extended from S-wave to P- and D-wave. The parameters of the model are determined by K{sup {minus}}p scattering cross section data, K{sup {minus}}p {yields}{Sigma}{pi}{pi}{pi} production data, K{sup {minus}}p threshold branching ratio data, and K{sup {minus}}p {yields}{Lambda}{pi}{pi}{pi} production data. The resonance structure of the {Lambda}(1405), {Sigma}(1385), and {Lambda}(1520) are studied in the model. The shift and width of kaonic hydrogen are calculated u… more
Date: May 15, 1992
Creator: He, Guangliang
Partner: UNT Libraries Government Documents Department
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Studies of the structure and function of Mms6, a bacterial protein that promotes the formation of magnetic nanoparticles

Description: Here we report structural and functional studies of Mms6, a biomineralization protein that can promote the formation in vitro of magnetic nanoparticles with sizes and morphologies similar to the magnetites synthesized by magnetotactic bacteria. We found the binding pattern of Mms6 to ferric ion to be two-phase and multivalent. We quantatively determined that Mms6 binds one Fe{sup 3+} with a very high affinity (K{sub d} = 10{sup -16} M). The second phase of iron binding is multivalent and cooper… more
Date: May 15, 2011
Creator: Wang, Lijun
Partner: UNT Libraries Government Documents Department
open access

Mesoporous silica nanoparticles as smart and safe devices for regulating blood biomolecule levels

Description: Stimuli-responsive end-capped MSN materials are promising drug carriers that securely deliver a large payload of drug molecules without degradation or premature release. A general review of the recent progress in this field is presented, including a summary of a series of hard and soft caps for drug encapsulation and a variety of internal and external stimuli for controlled release of different therapeutics, a discussion of the biocompatibility of MSN both in vitro and in vivo, and a descriptio… more
Date: May 15, 2011
Creator: Zhao, Yan
Partner: UNT Libraries Government Documents Department
open access

I. THE THEORY OF ABERRATIONS OF QUADRUPOLE FOCUSING ARRAYS. II. ION OPTICAL DESIGN OF HIGH QUALITY EXTRACTED SYNCHROTRON BEAMS WITH APPLICATION TO THE BEVATRON

Description: In Part One they formulate in a general way the problem of analyzing and evaluating the aberrations of quadrupole magnet beam systems, and of characterizing the shapes and other properties of the beam envelopes in the neighborhood of foci. They consider all aberrations, including those due to misalignments and faulty construction, through third order in small parameters, for quadrupole beam systems. One result of this study is the development of analytic and numerical techniques for treating th… more
Date: May 15, 1963
Creator: Meads Jr., Philip Francis
Partner: UNT Libraries Government Documents Department
open access

Laser desorption/ionization mass spectrometry for direct profiling and imaging of small molecules from raw biological materials

Description: Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral i… more
Date: May 15, 2008
Creator: Cha, Sangwon
Partner: UNT Libraries Government Documents Department
open access

Self-assembled pentablock copolymers for selective and sustained gene delivery

Description: The poly(diethylaminoethyl methacrylate) (PDEAEM) - Pluronic F127 - PDEAEM pentablock copolymer (PB) gene delivery vector system has been found to possess an inherent selectivity in transfecting cancer cells over non-cancer cells in vitro, without attaching any targeting ligands. In order to understand the mechanism of this selective transfection, three possible intracellular barriers to transfection were investigated in both cancer and non-cancer cells. We concluded that escape from the endocy… more
Date: May 15, 2011
Creator: Zhang, Bingqi
Partner: UNT Libraries Government Documents Department
open access

Dynamic magnetic susceptibility of systems with long-range magnetic order

Description: The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, ?, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies ({approx}10-3… more
Date: May 15, 2009
Creator: Vannette, Matthew Dano
Partner: UNT Libraries Government Documents Department
open access

Design and Synthesis of Mixed Oxides Nanoparticles for Biofuel Applications

Description: The work in this dissertation presents the synthesis of two mixed metal oxides for biofuel applications and NMR characterization of silica materials. In the chapter 2, high catalytic efficiency of calcium silicate is synthesized for transesterfication of soybean oil to biodisels. Chapter 3 describes the synthesis of a new Rh based catalyst on mesoporous manganese oxides. The new catalyst is found to have higher activity and selectivity towards ethanol. Chapter 4 demonstrates the applications of… more
Date: May 15, 2010
Creator: Chen, Senniang
Partner: UNT Libraries Government Documents Department
open access

Mesoporous silica nanoparticles for biomedical and catalytical applications

Description: Mesoporous silica materials, discovered in 1992 by the Mobile Oil Corporation, have received considerable attention in the chemical industry due to their superior textual properties such as high surface area, large pore volume, tunable pore diameter, and narrow pore size distribution. Among those materials, MCM-41, referred to Mobile Composition of Matter NO. 41, contains honeycomb liked porous structure that is the most common mesoporous molecular sieve studied. Applications of MCM-41 type mes… more
Date: May 15, 2011
Creator: Sun, Xiaoxing
Partner: UNT Libraries Government Documents Department
open access

The theoretical study of passive and active optical devices via planewave based transfer (scattering) matrix method and other approaches

Description: In this thesis, we theoretically study the electromagnetic wave propagation in several passive and active optical components and devices including 2-D photonic crystals, straight and curved waveguides, organic light emitting diodes (OLEDs), and etc. Several optical designs are also presented like organic photovoltaic (OPV) cells and solar concentrators. The first part of the thesis focuses on theoretical investigation. First, the plane-wave-based transfer (scattering) matrix method (TMM) is bri… more
Date: May 15, 2011
Creator: Zhuo, Ye
Partner: UNT Libraries Government Documents Department
open access

Reaction selectivity studies on nanolithographically-fabricated platinum model catalyst arrays

Description: In an effort to understand the molecular ingredients of catalytic activity and selectivity toward the end of tuning a catalyst for 100% selectivity, advanced nanolithography techniques were developed and utilized to fabricate well-ordered two-dimensional model catalyst arrays of metal nanostructures on an oxide support for the investigation of reaction selectivity. In-situ and ex-situ surface science techniques were coupled with catalytic reaction data to characterize the molecular structure of… more
Date: May 15, 2004
Creator: Grunes, Jeffrey Benjamin
Partner: UNT Libraries Government Documents Department
open access

Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

Description: Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and other complementary surface-sensitive techniques have been used to study the surface molecular structure and surface mechanical behavior of biologically-relevant polymer systems. SFG and AFM have emerged as powerful analytical tools to deduce structure/property relationships, in situ, for polymers at air, liquid and solid interfaces. The experiments described in this dissertation have been performed to u… more
Date: May 15, 2004
Creator: Koffas, Telly Stelianos
Partner: UNT Libraries Government Documents Department
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