Abstract Vinyl chloride, vinyl fluoride, and tetrafluoroethylene were polymerized in a radio frequency electric glow discharge. It was found that when compared with the unhalogenated simple hydrocarbons, the rates of polymer deposition are in the order vinyl chloride, acetylene, tetrafluoroethylene, vinyl fluoride, ethylene. This observation can be rationalized by considering the ease with which free radical and unsaturated species can be formed in the plasma. IR spectra show that the structures of plasma-polymerized vinyl chloride and vinyl fluoride are in many respects similar to the plasma-polymerized hydrocarbon. The spectrum of plasma-polymerized tetrafluoroethylene, however, does not resemble that of conventional polytetrafluoroethylene. Addition of dichlorodifluoromethane to the monomer stream dramatically increased the polymer deposition rate; the effect is more subdued for chloromethane and is negligible for tetrafluoromethane. Elemental analysis indicates that little of the added halogens is present in the resultant polymers. Thus the halogenated compounds appear to act as a gas phase catalyst for the plasma polymerization of hydrocarbons.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCatecholborane Bound to Titanocene. Unusual Coordination of Ligand σ-BondsJohn F. Hartwig, Clare N. Muhoro, Xiaoming He, Odile Eisenstein, Ramon Bosque, and Feliu MaserasView Author Information Department of Chemistry, Yale University P.O. Box 208107, New Haven, Connecticut 06520-8107 Laboratoire de Structure et Dynamique des Systemes̀ Moléculaires et Solides, UMR 5636 Université de Montpellier II, Montpellier, France Cite this: J. Am. Chem. Soc. 1996, 118, 44, 10936–10937Publication Date (Web):November 6, 1996Publication History Received21 June 1996Published online6 November 1996Published inissue 1 January 1996https://pubs.acs.org/doi/10.1021/ja962086vhttps://doi.org/10.1021/ja962086vrapid-communicationACS PublicationsCopyright © 1996 American Chemical SocietyRequest reuse permissionsArticle Views1637Altmetric-Citations146LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Addition reactions,Anions,Group 13 compounds,Inorganic compounds,Nuclear magnetic resonance spectroscopy Get e-Alerts
In this paper, we proposed a discrete-time cellular neural network (DTCNN) structure for the labelling of digital images. First, we present the concept and the structure of reversible DTCNN, which can be used to generate 2D binary random image sequences. Then both the original image and the copyright label, which is often another binary image, are used to generate a binary random key image. The key image is then used to scramble the original image. Due to the reversibility of a reversible DTCNN, the same reversible DTCNN is used to recover the copyright label from a labelled image. Due to the high speed of a DTCNN chip, our method can be used to label image sequences, e.g., video sequences, in real time. Computer simulation results are presented.
We have confirmed that the precursor star of the unusual Supernova 1954J (also known as Variable 12) in NGC 2403 survived what appears to have been a super-outburst, similar to the 1843 Great Eruption of eta Carinae in the Galaxy. The apparent survivor has changed little in brightness and color over the last eight years, and a Keck spectrum reveals characteristics broadly similar to those of eta Car. This is further suggested by our identification of the actual outburst-surviving star in high-resolution images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope. We reveal this ``supernova impostor'' as a highly luminous (M_V^0 ~ -8.0 mag), very massive (M_initial >~ 25 Msun) eruptive star, now surrounded by a dusty (A_V ~ 4 mag) nebula, similar to eta Car's famous Homunculus.
First-time demonstration of constitutive isoprene hydrocarbons production in a fermentative eukaryote operated through the mevalonic acid pathway. The work provides concept validation for the utilization of S. cerevisiae, as a platform for the production of volatile hydrocarbon biofuels and chemicals.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Rutile GeO<sub>2</sub> and related materials are attracting interest due to their ultrawide band gaps and potential for ambipolar doping in high-power electronic applications. This study examines the growth of rutile Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub> films through oxygen-plasma-assisted hybrid molecular beam epitaxy (hMBE). The film composition and thickness are evaluated across a range of growth conditions, with the outcomes rationalized by using density functional theory calculations. We find that up to 34% Ge can be successfully incorporated into Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub>/r-Al<sub>2</sub>O<sub>3</sub> (<i>x</i> ≤ 0.34) at 600 °C. Our phase diagram calculations suggest that spinodal decomposition occurs at Ge concentrations exceeding 34%. However, the formation of a Ge-rich rutile phase is inhibited by amorphization of the Ge-rich film and volatility of GeO. We therefore speculate that maximizing the Ge content requires higher Ge flux and more oxidizing environments, providing insights into the growth mechanism of Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub> and paving the way toward the synthesis of pure rutile GeO<sub>2</sub> films.
Rooted in structural dynamics theory, three approximate procedures for estimating seismic demands for bridges crossing fault-rupture zones and deforming into their inelastic range are presented: modal pushover analysis (MPA), linear dynamic analysis, and linear static analysis. These procedures estimate the total seismic demand by superposing peak values of quasi-static and dynamic parts. The peak quasi-static demand in all three procedures is computed by nonlinear static analysis of the bridge subjected to peak values of all support displacements applied simultaneously. In the MPA and the linear dynamic analysis procedures, the peak dynamic demand is estimated by nonlinear static (or pushover) analysis and linear static analysis, respectively, for forces corresponding to the most-dominant mode. In the linear static analysis procedure, the peak dynamic demand is estimated by linear static analysis of the bridge due to lateral forces appropriate for bridges crossing fault-rupture zones. The three approximate procedures are shown to provide estimates of seismic demands that are accurate enough to be useful for practical applications. The linear static analysis procedure, which is much simpler than the other two approximate procedures, is recommended for practical analysis of “ordinary” bridges because it eliminates the need for mode shapes and vibration periods of the bridge.
El avance del Estado penal en Norteamérica. En este artículo se analiza la creciente importancia del sector carcelario en los Estados Unidos como elemento de una política que pretende criminalizar la pobreza y sus consecuencias, sentando así las bases de un nuevo régimen de salariado precario y desocializado como norma de ciudadanía y acabando con los tradicionales mecanismos de contención utilizados para mantener el orden racial. Se examinan tres modalidades del avance del Estado penal : 1) la instalación de un régimen de hiperinflación carcelaria permanente y generalizada, sin precedentes en una sociedad democrática : la población penitenciaria estadounidense se cuadruplica entre 1975 y 1995, ascendiendo a más de 1.700.000 detenidos (647 por 100.000 habitantes) en 1997, mientras la criminalidad se estanca, e incluso disminuye ; 2) la extension lateral de la « red penal » y el aumento correlativo de los medios indirectes de vigilancia y control de los pobres : en quince años, el número de norteamericanos bajo tutela penal aumenta de tres millones, llegando a 5.400.000 en 1995, es decir uno de cada veinte hombres y uno de cada diez negros (al mismo tiempo se vigila a 30 millones de personas por medio de « ficheros criminales » informatizados) ; 3) el aumento espectacular del presupuesto y el personal de las distintas administraciones penitenciarias (cuyas plantillas se duplican entre 1980 y 1993, haciendo de la administración penitenciaria el segundo empleador del país) en el momento mismo en que el Estado reduce el gasto público destinado a los grupos de población mas desfavorecidos. La deliberada atrofia del Estado social y la hipertrofia del Estado penal en los Estados Unidos, durante el último cuarto de siglo, se desarrollan como procesos concomitantes y complementarios que intervienen en la instalación de un nuevo gobierno de la miseria en cuyo seno, contrariamente a lo previsto por los analistas de la escena penal de la decada del 70, la prisión ocupa una posición central. En cuanto a los grupos relegados a los niveles inferiores del espacio social estadounidense, esto se traduce en una severa y puntillosa puesta bajo tutela que obedece a un paternalismo de Estado.
Abstract Minor lymphocyte-stimulating (Mls) Ag are alloantigens that stimulate T cells expressing specific V beta regions. Recent studies have established that Mls Ag are examples of endogenous superantigens encoded by the products of endogenous mouse mammary tumor virus (MLV) genomes. In a mouse strain that expresses a given mammary tumor virus (Mls) Ag, reactive T cells expressing the corresponding V beta region are profoundly deficient, due at least in part to clonal deletion of the cells during their development. Expression of Mls and other endogenous superantigens, therefore, results in profound alterations in the ultimate repertoire of T cells in an animal. A role for endogenous superantigens in positive selection of T cells has not been previously established. Here we present evidence that expression of Mls-1a leads to a specific increase in the abundance of V beta 14+ T cells. Genetic studies indicate linkage of the effect to the Mls-1a gene. Neonatal tolerance studies argue against the possibility that the increase is due solely to the deletion of Mls-reactive V beta 14- T cells. The results are consistent with the Mls-1a product playing a role in the positive selection of V beta 14+ T cells.
