Ferroelectric characterization and growth optimization of thermally evaporated vinylidene fluoride thin films

Organic thin films have numerous advantages over inorganics in device processing and price. The large polarization of the organic ferroelectric oligomer vinylidene fluoride (VDF) could prove useful for both device applications and the investigation of fundamental physical phenomena. A VDF oligomer thin film vacuum deposition process, such as thermal evaporation, preserves film and interface cleanliness, but is challenging, with successful deposition occurring only within a narrow parameter space. We report on the optimal deposition parameters for VDF oligomer thin films, refining the parameter space for successful deposition, resulting in a high yield of robust ferroelectric films. In particular, we investigate the influence of deposition parameters on surface roughness, and the role that roughness plays in sample yield. The reliable production of ferroelectric films allowed us to perform detailed measurements of previously unreported properties, including the Curie temperature, the temperature and thickness dependence of the coercive field, the melting temperature, and the index of refraction. The ability to successfully grow robust, switchable, well-characterized films makes VDF oligomer a viable candidate in the field of organic ferroelectrics

Letter from G. C. Shearer to the pastor of the Christian Church

Letter from G. C. Shearer to the pastor of the Christian Church in Gainesville, Florida. The one-page handwritten note is on G. C. Shearer letterhead and is dated 13 February 1910. There is a transcript of the correspondence in the item PDF

Enhanced surface functionality via plasma modification and plasma deposition techniques to create more biologically relevant materials

2013 Summer.Includes bibliographical references.Functionalizing nanoparticles and other unusually shaped substrates to create more biologically relevant materials has become central to a wide range of research programs. One of the primary challenges in this field is creating highly functionalized surfaces without modifying the underlying bulk material. Traditional wet chemistry techniques utilize thin film depositions to functionalize nanomaterials with oxygen and nitrogen containing functional groups, such as -OH and -NHx. These functional groups can serve to create surfaces that are amenable to cell adhesion or can act as reactive groups for further attachment of larger structures, such as macromolecules or antiviral agents. Additional layers, such as SiO2, are often added between the nanomaterial and the functionalized coating to act as a barrier films, adhesion layers, and to increase overall hydrophilicity. However, some wet chemistry techniques can damage the bulk material during processing. This dissertation examines the use of plasma processing as an alternative method for producing these highly functionalized surfaces on nanoparticles and polymeric scaffolds through the use of plasma modification and plasma enhanced chemical vapor deposition techniques. Specifically, this dissertation will focus on (1) plasma deposition of SiO2 barrier films on nanoparticle substrates; (2) surface functionalization of amine and alcohol groups through (a) plasma co-polymerization and (b) plasma modification; and (3) the design and construction of plasma hardware to facilitate plasma processing of nanoparticles and polymeric scaffolds. The body of work presented herein first examines the fabrication of composite nanoparticles by plasma processing. SiOxCy and hexylamine films were coated onto TiO2 nanoparticles to demonstrate enhanced water dispersion properties. Continuous wave and pulsed allyl alcohol plasmas were used to produce highly functionalized Fe2O3 supported nanoparticles. Specifically, film composition was correlated to gas-phase excited state species and the pulsing duty cycle to better understand the mechanisms of allyl alcohol deposition in our plasma systems. While these studies specifically examined supported nanoparticle substrates, some applications might require the complete functionalization of the entire nanoparticle surface. To overcome this challenge, a rotating drum plasma reactor was designed as a method for functionalizing the surface of individual Fe2O3 nanoparticles. Specifically, data show how the rotating motion of the reactor is beneficial for increasing the alcohol surface functionality of the nanoparticles when treated with pulsed allyl alcohol plasmas. Plasma copolymerization was used to deposit films rich in both oxygen and nitrogen containing functional groups using allyl alcohol and allyl amine plasma systems. Functional group retention and surface wettability was maximized under pulsed plasma conditions, and films produced under pulsed plasma conditions did not exhibit hydrophobic recovery or experience loss of nitrogen as the films aged. Plasma surface modification with N2/H2O and NH3/H2O, and plasma deposition with allyl alcohol and allyl amine, were used to increase the wettability of poly(caprolactone) scaffolds while simultaneously implanting functional groups onto the scaffold surface and into the scaffold core. While plasma deposition methods did not modify the internal core of the scaffold as much as modification methods, it afforded the ability to have higher water absorption rates after a three week aging period. Additionally, cell viability studies were conducted with N2/H2O plasma treated scaffolds and showed enhanced cell growth on plasma treated scaffolds over non plasma-treated scaffolds

Fact and Fiction Concerning Multinational Labor Relations

This article briefly reviews the magnitude, nature, and growth of the foreign investments of American-based MNCs, especially those in the nine member countries of the European Community (EC), and summarizes the major union fears and aspirations that arise from the rapid growth in scope and power of MNCs. The article focuses on the realities and fantasies surrounding the prospects for multinational collective bargaining with MNCs, which is widely viewed as the most feasible means by which unions can protect their vital interests threatened by MNCs. Unfortunately, in discussions of this matter considerable fiction is often mixed with fact. Some observers see international unionism and multinational collective bargaining as natural concommitants of the internationalization of production and product markets through the spread of MNCs, and they view these developments as the transnational extension of the phenomenon that has characterized the evolution of domestic union structures in response to the national widening of production and of product markets. In their fascination with the bold notion of the internationalization of collective bargaining it is tempting for commentators to allow abstract ideas and aspirations to prevail over realities. As background, the discussion includes a brief description of how American-based MNCs structure and manage their overseas labor relations policies and practices, the nature of the American industrial relations environment in which they operate, and the considerable differences in the industrial relations environments in the EC countries. The article concludes with a discussion of the union responses, both international and domestic, to the MNCs and, finally, with the effects of recent EC developments on the prospects for multinational collective bargaining there

Stabilized lanthanum sulphur compounds

Lanthanum sulfide is maintained in the stable cubic phase form over a temperature range of from 500 C to 1500 C by adding to it small amounts of calcium, barium, or strontium. This compound is an excellent thermoelectric material

Long Duration Exposure Facility (LDEF) structural verification test report

Structural load tests on the Long Duration Exposure Facility's (LDEF) primary structure were conducted. These tests had three purposes: (1) demonstrate structural adequacy of the assembled LDEF primary structure when subjected to anticipated flight loads; (2) verify analytical models and methods used in loads and stress analysis; and (3) perform tests to comply with the Space Transportation System (STS) requirements. Test loads were based on predicted limit loads which consider all flight events. Good agreement is shown between predicted and observed load, strain, and deflection data. Test data show that the LDEF structure was subjected to 1.2 times limit load to meet the STS requirements. The structural adequacy of the LDEF is demonstrated

Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection

We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their agyclone structures, 2-methyl-3-(3-3-carboxymethylpropyl)-1,4-naphthoquinone (5C-side-chain metabolite) and 2-methyl-3-(5-carboxy-3-methyl-2-pentenyl)-1,4-naphthoquinone (7C-side-chain metabolite), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid phase extraction (SPE) and the predominately conjugated vitamin K metabolites hydrolysed with methanolic HCl. The resultant carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE. Final analysis was by reversed-phase (C18) HPLC with a methanol-aqueous mobile phase. Metabolites were detected by amperometric, oxidative ECD of their quinol forms, which were generated by post-column coulometric reduction at an upstream electrode. The assay gave excellent linearity (r2 typically = 0.999) and high sensitivity with an on-column detection limit of <3.5 fmol (<1pg). The inter-assay precision was typically 10%. Metabolite recovery was compared to that of an internal standard (2-methyl-3-(7'-carboxy-heptyl)-1,4-naphthoquinone), added to urine samples just before analysis. Using this methodology we confirmed that the 5C- and 7C-metabolite were major catabolites of both phylloquinone (vitamin K1) and menaquinones (vitamin K2) in humans. We propose that the measurement of urinary vitamin K metabolite excretion is a candidate non-invasive marker of total vitamin K status

An experimental study investigating the ability of volunteers to identify squirrel species from tail–hair samples

Un estudio experimental sobre la capacidad de los voluntarios de reconocer las especies de ardilla a partir de muestras de pelo de la cola Las trampas de pelo, que permiten recoger los pelos de la nuca, se utilizan ampliamente para establecer la presencia de la ardilla común (Sciurus vulgaris) y la ardilla gris (Sciurus carolinensis). No obstante, es un método que requiere mucho tiempo y se presta a errores de identificación. Una alternativa es recoger pelos de la cola mediante cintas adhesivas colocadas en postes que sostienen un cebo en la parte superior. Sin embargo, no existen datos sobre la precisión de la identificación del pelo de la cola. En este estudio se informa de un experimento en que se ofreció una breve sesión formativa a las personas antes de que identificaran las muestras de pelo de las cuatro especies. El índice de identificación correcta fue del 96,5% para los pelos de la ardilla gris y del 77,5% para los de la ardilla común, lo que sugiere que los pelos de la cola pueden proporcionar un método rápido, fácil y preciso de identificar ambas especies.Hair–tubes, collecting nape hairs, are widely used for establishing the presence of red (Sciurus vulgaris) and grey (Sciurus carolinensis) squirrels. However it is time–consuming and prone to identification errors. An alternative is to collect tail hairs from sticky pads on baited poles. However, there is no evidence concerning identification accuracy of tail hairs. This study reports an experiment in which subjects underwent a short training session before identifying hair samples from four species. There was a 96.5% correct identification rate for grey squirrel hairs, and 77.5% for red squirrels, which suggests that tail hairs collection may provide a quick, easy and accurate method of identification for both species.Un estudio experimental sobre la capacidad de los voluntarios de reconocer las especies de ardilla a partir de muestras de pelo de la cola Las trampas de pelo, que permiten recoger los pelos de la nuca, se utilizan ampliamente para establecer la presencia de la ardilla común (Sciurus vulgaris) y la ardilla gris (Sciurus carolinensis). No obstante, es un método que requiere mucho tiempo y se presta a errores de identificación. Una alternativa es recoger pelos de la cola mediante cintas adhesivas colocadas en postes que sostienen un cebo en la parte superior. Sin embargo, no existen datos sobre la precisión de la identificación del pelo de la cola. En este estudio se informa de un experimento en que se ofreció una breve sesión formativa a las personas antes de que identificaran las muestras de pelo de las cuatro especies. El índice de identificación correcta fue del 96,5% para los pelos de la ardilla gris y del 77,5% para los de la ardilla común, lo que sugiere que los pelos de la cola pueden proporcionar un método rápido, fácil y preciso de identificar ambas especies