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2005

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Articles 631 - 660 of 738

Full-Text Articles in Physics

Nonlinear Optics And An Experimental Test Of Bell’S Inequality, Michael Herbst Jan 2005

Nonlinear Optics And An Experimental Test Of Bell’S Inequality, Michael Herbst

Honors Papers

The purpose of this investigation is to assemble an apparatus capable of testing Bell’s inequality for a local hidden variable. The historical context and theoretical developments that led to this area of inquiry are presented. Expected experimental results stemming from two distinct physical theories are introduced. Procedures are given that outline the assembly of a device capable of testing these theories. Analysis confirming the successful completion of a majority of the steps is presented, and the final necessary steps are detailed. Finally, a laboratory prompt for this experiment’s use in Oberlin College’s advanced laboratory class is given.

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The Quantum Dynamics Of H2 In A C60 Lattice, Christie Simmons Jan 2005

The Quantum Dynamics Of H2 In A C60 Lattice, Christie Simmons

Honors Papers

Since its onset in 1941, matrix isolation has become a popular and common technique for studying species using spectroscopy by isolating them in an inert host solid [1]. Due to the large, spherical shape of the molecules, solid C60 has large interstitial voids making it a good host for matrix isolation. These voids come in two varieties. The larger of the two, the octahedral sites, have an ideal size for studying the dynamics of H2 molecules because the sites are large enough that a hydrogen molecule can be trapped, resulting in quantized translational motion, and can rotate nearly freely within …

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Discovery Of Pulsed Oh Emission Stimulated By A Pulsar, Joel M. Weisberg, Simon Johnston, Barbel Koribalski, Snezana Stanimirovic Jan 2005

Discovery Of Pulsed Oh Emission Stimulated By A Pulsar, Joel M. Weisberg, Simon Johnston, Barbel Koribalski, Snezana Stanimirovic

Physics and Astronomy Faculty Work

Curium lies at the center of the actinide series and has a half-filled shell with seven 5f electrons spatially residing inside its radon core. As a function of pressure, curium exhibits five different crystallographic phases up to 100 gigapascals, of which all but one are also found in the preceding element, americium. We describe here a structure in curium, Cm III, with monoclinic symmetry, space group C2/c, found at intermediate pressures (between 37 and 56 gigapascals). Ab initio electronic structure calculations agree with the observed sequence of structures and establish that it is the spin polarization of curium’s 5f electrons …

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The Effect Of Preparation Conditions On The Growth Rate Of Films, The Yield Of Precipitated Powder And The Dc Conductivity Of Polypyrrole, S. A. Saafan, M. M. Ayad, E. H. El-Ghazzawy Jan 2005

The Effect Of Preparation Conditions On The Growth Rate Of Films, The Yield Of Precipitated Powder And The Dc Conductivity Of Polypyrrole, S. A. Saafan, M. M. Ayad, E. H. El-Ghazzawy

Turkish Journal of Physics

Polypyrrole (PPy) was prepared by a chemical method by using oxidizing agents ferric chloride and potassium persulphate, both as films and pellets. The effect of various variables-such as aging of the films, film thickness, ratios of the reactants and type of the sample (film or disc)-on DC conductivity were investigated. The results from samples prepared with ferric chloride exhibited an increase in conductivity with increasing concentration of oxidizing agent to a certain ratio, above which a slight decrease occurs. Whereas in the case of using potassium persulphate as the oxidizing agent, a decrease in conductivity occurs with increasing its concentration. …

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Applications Of Discoveries Range From Leveling Rice Fields To Anti-Terrorism Defenses, Aldemaro Romero Jr., Susan D. Allen Jan 2005

Applications Of Discoveries Range From Leveling Rice Fields To Anti-Terrorism Defenses, Aldemaro Romero Jr., Susan D. Allen

Publications and Research

No abstract provided.

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Cluster Issue On Microplasmas, Kurt H. Becker, J. Gary Eden, Karl H. Schoenbach Jan 2005

Cluster Issue On Microplasmas, Kurt H. Becker, J. Gary Eden, Karl H. Schoenbach

Bioelectrics Publications

Atmospheric-pressure diffuse discharge plasmas are susceptible to instabilities and, in particular, to arcing (the glow-to-arc transition). Some of the most promising approaches to ‘stabilizing’ atmospheric-pressure plasmas are based on the recognition that arc formation can be avoided when the plasmas are generated and maintained in spatially constricted geometries with dimensions from tens to hundreds of microns. Known as microplasmas or microdischarges, these weakly-ionized discharges represent a new and fascinating realm of plasma science in which several scientific issues, such as the potential breakdown of pd scaling and the role of boundary-based phenomena, come to the fore. In contrast to ‘macroplasmas’ …

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Predicted Properties Of Microhollow Cathode Discharges In Xenon, J. P. Boeuf, L. C. Pitchford, K. H. Schoenbach Jan 2005

Predicted Properties Of Microhollow Cathode Discharges In Xenon, J. P. Boeuf, L. C. Pitchford, K. H. Schoenbach

Bioelectrics Publications

A fluid model has been developed and used to help clarify the physical mechanisms occurring in microhollow cathode discharges (MHCD). Calculated current-voltage (I-V) characteristics and gas temperatures in xenon at 100 Torr are presented. Consistent with previous experimental results in similar conditions, we find a voltage maximum in the I-V characteristic. We show that this structure reflects a transition between a low-current, abnormal discharge localized inside the cylindrical hollow cathode to a higher-current, normal glow discharge sustained by electron emission from the outer surface of the cathode. This transition, due to the geometry of …

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Condensation On (002) Graphite Of Liquid Bismuth Far Below Its Bulk Melting Point, M. K. Zayed, H. E. Elsayed-Ali Jan 2005

Condensation On (002) Graphite Of Liquid Bismuth Far Below Its Bulk Melting Point, M. K. Zayed, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Condensation of thermally evaporated Bi on (002) graphite, at temperatures of 300-523K, was studied using in situ reflection high-energy electron diffraction (RHEED) and room temperature ex situ atomic force microscopy (AFM). For deposition at temperatures below 415±5K, transmission RHEED patterns of Bi appeared at an average thickness of ∼0.5 monolayer (ML). AFM images showed that the film consisted of crystallites in the shape of triangular step pyramids with step heights corresponding to single and double Bi layers in the [111] direction. This morphology indicates crystallization from the vapor. For deposition at higher temperatures, diffuse RHEED patterns appeared independent of the …

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Antisymmetric Magnetoresistance In Magnetic Multilayers With Perpendicular Anisotropy, Xuemei Cheng, S. Urazhdin, O. Tchernyshyov, C. L. Chien, V. I. Nikitenko, A. J. Shapiro, R. D. Shull Jan 2005

Antisymmetric Magnetoresistance In Magnetic Multilayers With Perpendicular Anisotropy, Xuemei Cheng, S. Urazhdin, O. Tchernyshyov, C. L. Chien, V. I. Nikitenko, A. J. Shapiro, R. D. Shull

Physics Faculty Research and Scholarship

While magnetoresistance (MR) has generally been found to be symmetric in applied field in nonmagnetic or magnetic metals, we have observed antisymmetric MR in Co/Pt multilayers. Simultaneous domain imaging and transport measurements show that antisymmetric MR is due to the appearance of domain walls that run perpendicular to both the magnetization and the current, a geometry existing only in materials with perpendicular magnetic anisotropy. As a result, the extraordinary Hall effect gives rise to circulating currents in the vicinity of domain walls that contributes to the MR. The antisymmetric MR and extraordinary Hall effect have been quantitatively accounted for by …

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Force-Velocity Correlations In A Dense, Collisional, Granular Flow, Emily Gardel, Ellen Keene, Sonia Dragulin, Nalini Easwar, Narayanan Menon Jan 2005

Force-Velocity Correlations In A Dense, Collisional, Granular Flow, Emily Gardel, Ellen Keene, Sonia Dragulin, Nalini Easwar, Narayanan Menon

Physics: Faculty Publications

We report measurements in a 2-dimensional, gravity-driven, collisional, granular flow of the normal force delivered to the wall and of particle velocity at several points in the flow. The wall force and the flow velocity are negatively correlated. This correlation falls off only slowly when the wall force is correlated against the flow velocity at various locations across the channel, but dies away on the scale of a few particle diameters upstream or downstream. The data support a picture of short-lived chains of frequently colliding particles that extend transverse to the flow direction, making transient load-bearing bridges that cause bulk …

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An Investigation Of The Effect Of Variation In Surface Electrode Type And Placement On Action Potentials Elicited By Peripheral Nerve Simulation, Jacinta Augustine Jan 2005

An Investigation Of The Effect Of Variation In Surface Electrode Type And Placement On Action Potentials Elicited By Peripheral Nerve Simulation, Jacinta Augustine

Masters

Several experiments were designed and carried out in order to compare the performances of five commercially available EMG surface electrodes. The aim was to identify the optimal surface recording electrode from the samples examined. The particular interest was to assess the comparative performance of the electrodes routinely used in our hospital Neurophysiology laboratory. It is envisaged that the conclusions from the study might be applied to improve the quality and reproducibility of nerve conduction techniques use din our department. A literature survey was carried out to identify some of the factors that influence the recording of evoked potentials from peripheral …

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Design Of A Dynamic Focusing Microscope Objective For Oct Imaging, Supraja Murali Jan 2005

Design Of A Dynamic Focusing Microscope Objective For Oct Imaging, Supraja Murali

Electronic Theses and Dissertations

Optical Coherence Tomography (OCT) is a novel optical imaging technique that has assumed significant importance in bio-medical imaging in the last two decades because it is non-invasive and provides accurate, high resolution images of three dimensional cross-sections of body tissue, exceeding the capabilities of the current predominant imaging technique –ultrasound. In this thesis, high resolution OCT is investigated for in vivo detection of abnormal skin pathology for the early diagnosis of cancer. The technology presented is based on a dynamic focusing microscopic imaging probe conceived for skin imaging and the detection of abnormalities in the epithelium. A novel method for …

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A New Form Of Matter — Unmatter, Composed Of Particles And Anti-Particles, Florentin Smarandache Jan 2005

A New Form Of Matter — Unmatter, Composed Of Particles And Anti-Particles, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

Besides matter and antimatter there must exist unmatter (as a new form of matter) in accordance with the neutrosophy theory that between an entity (a) and its opposite there exist intermediate entities . Unmatter is neither matter nor antimatter, but something in between. An atom of unmatter is formed either by (1): electrons, protons, and antineutrons, or by (2): antielectrons, antiprotons, and neutrons. At CERN it will be possible to test the production of unmatter. The existence of unmatter in the universe has a similar chance to that of the antimatter, and its production also difficult for present technologies.

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Quantum Quasi-Paradoxes And Quantum Sorites Paradoxes, Florentin Smarandache Jan 2005

Quantum Quasi-Paradoxes And Quantum Sorites Paradoxes, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

There can be generated many paradoxes or quasi-paradoxes that may occur from the combination of quantum and non-quantum worlds in physics. Even the passage from the micro-cosmos to the macro-cosmos, and reciprocally, can generate unsolved questions or counter-intuitive ideas. We define a quasi-paradox as a statement which has a prima facie self-contradictory support or an explicit contradiction, but which is not completely proven as a paradox. We present herein four elementary quantum quasi-paradoxes and their corresponding quantum Sorites paradoxes, which form a class of quantum quasi-paradoxes.

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Exclusive Ρ0 Meson Electroproduction From Hydrogen At Clas, C. Hadjidakis, M. Guidal, M. Garçon, J.-M. Laget, E. S. Smith, M. Vanderhaeghen, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, H. Bagdasaryan, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, M. Guler, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, R. A. Niyazov, L. M. Qin, F. Sabatie, L. B. Weinstein, J. Yun Jan 2005

Exclusive Ρ0 Meson Electroproduction From Hydrogen At Clas, C. Hadjidakis, M. Guidal, M. Garçon, J.-M. Laget, E. S. Smith, M. Vanderhaeghen, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, H. Bagdasaryan, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, M. Guler, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, R. A. Niyazov, L. M. Qin, F. Sabatie, L. B. Weinstein, J. Yun

Physics Faculty Publications

The longitudinal and transverse components of the cross section for the ep → e′ pρ0 reaction were measured in Hall B at Jefferson Laboratory using the CLAS detector. The data were taken with a 4.247 GeV electron beam and were analyzed in a range of xB from 0.2 to 0.6 and of Q2 from 1.5 to 3.0 GeV2. The data are compared to a Regge model based on effective hadronic degrees of freedom and to a calculation based on Generalized Parton Distributions. It is found that, at our lowest xB values, the transverse part of the …

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High-Energy Effective Action From Scattering Of Qcd Shock Waves, Ian Balitsky Jan 2005

High-Energy Effective Action From Scattering Of Qcd Shock Waves, Ian Balitsky

Physics Faculty Publications

At high energies, the relevant degrees of freedom are Wilson lines—infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.

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Global Analysis Of Data On The Proton Structure Function G₁ And The Extraction Of Its Moments, M. Osipenko, S. Simula, W. Melnitchouk, P. Bosted, V. Burkert, E. Christy, K. Griffioen, C. Keppel, S. Kuhn, G. Ricco Jan 2005

Global Analysis Of Data On The Proton Structure Function G₁ And The Extraction Of Its Moments, M. Osipenko, S. Simula, W. Melnitchouk, P. Bosted, V. Burkert, E. Christy, K. Griffioen, C. Keppel, S. Kuhn, G. Ricco

Physics Faculty Publications

Inspired by recent measurements with the CLAS detector at Jefferson Lab, we perform a self-consistent analysis of world data on the proton structure function g1 in the range 0.17 < Q2 < 30 (GeV/c)2. We compute for the first time low-order moments of g, and study their evolution from small to large values of Q2. The analysis includes the latest data on both the unpolarized inclusive cross sections and the ratio R = σ L/σT from Jefferson Lab, as well as a new model for the transverse asymmetry A2 in the resonance region. The contributions of …

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Exclusive Photoproduction Of The Cascade Ξ Hyperons, H. Bagdasaryan, M. Bektasoglu, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. V. Klimenko, S. E. Kuhn, L. M. Qin, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration Jan 2005

Exclusive Photoproduction Of The Cascade Ξ Hyperons, H. Bagdasaryan, M. Bektasoglu, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, A. V. Klimenko, S. E. Kuhn, L. M. Qin, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration

Physics Faculty Publications

We report on the first measurement of exclusive Ξ-(1321) hyperon photoproduction in 𝛾p → K+K+Ξ- for 3.2 < E𝛾 < 3.9 GeV. The final state is identified by the missing mass in p(𝛾,K+K+)X measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground state Ξ-(1321)1/2+ and have estimated the total cross section for its production. We also have strong evidence for the first excited state Ξ-(1530)3/2+. Photoproduction provides a copious source of Ξ's. We discuss the possibilities of a search for the recently proposed Ξ5- and Ξ5+ …

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Kinetic Structure Simulations Of Nematic Polymers In Plane Couette Cells. Ii: In-Plane Structure Transitions, M. Gregory Forest, Ruhai Zhou, Qi Wang Jan 2005

Kinetic Structure Simulations Of Nematic Polymers In Plane Couette Cells. Ii: In-Plane Structure Transitions, M. Gregory Forest, Ruhai Zhou, Qi Wang

Mathematics & Statistics Faculty Publications

Nematic, or liquid crystalline, polymer (LCP) composites are composed of large aspect ratio rod-like or platelet macromolecules. This class of nanocomposites exhibits tremendous potential for high performance material applications, ranging across mechanical, electrical, piezoelectric, thermal, and barrier properties. Fibers made from nematic polymers have set synthetic materials performance standards for decades. The current target is to engineer multifunctional films and molded parts, for which processing flows are shear-dominated. Nematic polymer films inherit anisotropy from collective orientational distributions of the molecular constituents and develop heterogeneity on length scales that are, as yet, not well understood and thereby uncontrollable. Rigid LCPs in …

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Levitation Using Microwave-Induced Plasmas, R. J. Exton, S. Popovic, G. C. Herring, M. Cooper Jan 2005

Levitation Using Microwave-Induced Plasmas, R. J. Exton, S. Popovic, G. C. Herring, M. Cooper

Physics Faculty Publications

The levitation of objects above a microwave horn is demonstrated. High-power microwave pulses generate a low-temperature, diffuse plasma on the surface of the horn window. The thermal effect of the surface plasma brings about a localized increase in the pressure and results in a vertical flow of air, thus levitating the object.

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Variable Stars In The Field Of Open Cluster Ngc 6819 – Ii, R. A. Street, Keith Horne, T. A. Lister, A. Penny, Y. Tsapras, A. Quirrenbach, N. Safizadeh, J. Cooke, David Mitchell, A. Collier Cameron Jan 2005

Variable Stars In The Field Of Open Cluster Ngc 6819 – Ii, R. A. Street, Keith Horne, T. A. Lister, A. Penny, Y. Tsapras, A. Quirrenbach, N. Safizadeh, J. Cooke, David Mitchell, A. Collier Cameron

Physics

We report on the discovery of 141 further variable stars found in the field of the open cluster NGC 6819. The stars were identified from time-series photometric data obtained on the Isaac Newton Telescope, La Palma, during two observing runs covering the 19 nights between 1999 June 22–30 and 1999 July 22–31. The variables found include 53 eclipsing binaries, of which eight stars appear to be RS CVns, in addition to 70 stars showing spot activity, 13 showing long-period variability and five variables of other types.

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Structural Property Relationships In Conjugated Polymers, Patrick Lynch, Luke O'Neill, J. Whelan, Mary Mcnamara, Hugh Byrne Jan 2005

Structural Property Relationships In Conjugated Polymers, Patrick Lynch, Luke O'Neill, J. Whelan, Mary Mcnamara, Hugh Byrne

Articles

The synthesis of a series of PPV derivative polymers by the Wittig-Horner reaction is described. The structure of each polymer is varied and the effects of these variations on the optical properties is explored. The effects of alkyloxy side chains is observed between the PPV derivatives Poly(-p-phenylvinylene-co-2,5-bis-octyloxy phenylvinylene.) PPV-OPV and Poly (para-2,5-bis-(n-octyloxy)-phenylvinylene) POPV. The phenyl units of the soluble PPV derivative POPV are replaced by alternate naphthyl units in the polymer Poly(2,5-bis(n-octyloxy)-1,4-phenylene vinylene-1,5-bis(n-octyloxy)-2,6-naphthylene vinylene) POPN-ONV and then fully by naphthyl units in Poly(2,6-bis-(n-octyloxy)-1,5-NaphthyleneVinylene) PONV. The addition of alkyloxy sidechains served to red shift the fluorescence emission as expected. The systematic …

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Modernization Of The Hilger And Watts Guage-Block Interferometer, Michael O'Hora, Brian Bowe, Vincent Toal, Sean Peyton Jan 2005

Modernization Of The Hilger And Watts Guage-Block Interferometer, Michael O'Hora, Brian Bowe, Vincent Toal, Sean Peyton

Articles

The Hilger & Watts gauge-block interferometer was designed and manufactured commercially in the 1950s. The instrument uses isotope lamps as wavelength standards to perform absolute length calibration of gauge blocks (slip gauges) up to 100 mm in length, to an accuracy of approximately 1 ppm. It is entirely manually operated. In order to make the instrument more suitable for the modern laboratory, new hardware has been added, and a customized software package developed to automate the measurement process. This paper shows how interferograms may be imaged successfully at each of the eight available wavelengths, and the critical fringe fraction measurement …

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Characterisation Of An Acrylamide-Based Photopolymer For Data Storage Utilizing Holographic Angular Multiplexing, Hosam Sherif, Izabela Naydenova, Suzanne Martin, Colm Mcginn, Vincent Toal Jan 2005

Characterisation Of An Acrylamide-Based Photopolymer For Data Storage Utilizing Holographic Angular Multiplexing, Hosam Sherif, Izabela Naydenova, Suzanne Martin, Colm Mcginn, Vincent Toal

Articles

An acrylamide-based photopolymer formulated in the Centre for Industrial and Engineering Optics has been investigated with a view to further optimisation for holographic optical storage. Series of 18 to 30 gratings were angularly multiplexed in a volume of photopolymer layer at a spatial frequency of 1500 lines/mm. Since the photopolymer is a saturable material, an exposure scheduling method was used to exploit the entire dynamic range of the material and allow equal strength holographic gratings to be recorded. This investigation yielded the photopolymer M/# for moderately thin layers. Photopolymer temporal stability was also studied by measuring variations of material shrinkage, …

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Characterisation Of An Acrylamide-Based Photopolymer For Holographic Data Storage, Hosam Sherif Jan 2005

Characterisation Of An Acrylamide-Based Photopolymer For Holographic Data Storage, Hosam Sherif

Masters

An acrylamide-based photopolymer, formulated in the Centre for Industrial and Engineering Optics, was investigated as a recording material for holographic data storage applications. Holographic data storage (HDS) is an optical storage technique, which theoretically allows densities as high as tens of TB/cm2 with data transfer rates of many GB/s/. HDS has unique advantages, such as the ability to perform parallel data searches (associative recall) and implement novel encryption techniques. At present, many materials have been investigated to determine their suitability for use as HDS media. As yet, no one material possesses all the properties that are required to realise the …

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Investigation Of The Optical, Thermal, And Mechanical Properties Of A Bulk Polymer Using The Surface Thermal Lensing Technique, Bushra Hussain Jan 2005

Investigation Of The Optical, Thermal, And Mechanical Properties Of A Bulk Polymer Using The Surface Thermal Lensing Technique, Bushra Hussain

Master's Theses and Doctoral Dissertations

The sensitive and simple photothermal technique of Surface Thermal Lensing (STL) was employed to study the thermo-mechanical response of an amorphous polycarbonate as a bulk. A discussion is given of how previously developed theories did not fit well with the present work. Therefore, only qualitative analysis and discussion of the experimental results is made, emphasizing the influence of various factors on the STL signal. The work here is mainly a study of the dependence of the STL signal on the modulated pump beam frequency. The effect on the STL signal of thermal and mechanical relaxation in the thermally stimulated area …

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Optimization Of Ultraviolet Emission And Chemical Species Generation From A Pulsed Dielectric Barrier Discharge At Atmospheric Pressure, Xinpei Lu, Mounir Laroussi Jan 2005

Optimization Of Ultraviolet Emission And Chemical Species Generation From A Pulsed Dielectric Barrier Discharge At Atmospheric Pressure, Xinpei Lu, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

One of the attractive features of nonthermal atmospheric pressure plasmas is the ability to achieve enhanced gas phase chemistry without the need for elevated gas temperatures. This attractive characteristic recently led to their extensive use in applications that require low temperatures, such as material processing and biomedical applications. The agents responsible for the efficient plasma reactivity are the ultraviolet (UV) photons and the chemically reactive species. In this paper, in order to optimize the UV radiation and reactive species generation efficiency, the plasma was generated by a dielectric barrier discharge driven by unipolar submicrosecond square pulses. To keep the discharge …

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Synthesis And Mrs Nlo Characterization Of New Triarylmethyl Cations, Guilin Mao, Greg A. Wiggers, Rolfe G. Petschek, Kenneth D. Singer Jan 2005

Synthesis And Mrs Nlo Characterization Of New Triarylmethyl Cations, Guilin Mao, Greg A. Wiggers, Rolfe G. Petschek, Kenneth D. Singer

Faculty Scholarship

We report on the synthesis of new quadripolar triarylmethyl cations related to Crystal Violet and the characterization of their NLO properties by a new hyper Rayleigh scattering (HRS) technique. We have prepared a range of triarylmethyl cations that incorporate one, two or three naphthyl moieties. These structural modifications have a direct influence on the NLO properties that have been determined by the Timed-Correlated Single Photon Counting 45° HRS (TCSP-45-HRS) and also influence absorption properties as seen in the UV-Visible spectra.

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Effect Of Flexible Bimesogen Dopant On The Stability Of The Anticlinic Liquid-Crystal Phase, Min Hua Zhu, Rolfe G. Petschek, Charles Rosenblatt Jan 2005

Effect Of Flexible Bimesogen Dopant On The Stability Of The Anticlinic Liquid-Crystal Phase, Min Hua Zhu, Rolfe G. Petschek, Charles Rosenblatt

Faculty Scholarship

Small quantities of the floppy bimesogen di(4PPB5)3Si were dissolved in an anticlinic liquid crystal consisting of a mixture of left-handed and right-handed TFMHPOBC, with enantiomer excess X=0.2. The bimesogen dopant was found to promote anticlinic order with an anticlinic interaction coefficient per molecule udopant smaller than, but of the same order as, that of the rigid bent-core dopant P-7PIMB. For both dopants udopant was found to be much larger than that due to a pair of TFMHPOBC molecules in adjacent layers. The results are examined in terms of both the flexibility of the group linking the two legs of each …

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Room-Temperature Atmospheric Pressure Plasma For Biomedical Applications, Mounir Laroussi, Xinpei Lu Jan 2005

Room-Temperature Atmospheric Pressure Plasma For Biomedical Applications, Mounir Laroussi, Xinpei Lu

Electrical & Computer Engineering Faculty Publications

As low-temperature non-equilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little …

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