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1.
The energy interaction curves of a number of diatomic and polyatomic dication systems were calculated in order to study their energy-trapping properties. Generally, the ab initio complete active space multiconfiguration self-consistent field method was used in an extended valence + polarization basis set, with compact effective potentials replacing the core electrons. The diatomic dications include all ten possible binary combinations of oxygen, sulphur, selenium, and tellurium. O22+ shows the largest exothermicity, measured from equilibrium to the monocation combination asymptote, and highest barrier to dissociation. The calculated equilibrium bond length and harmonic vibrational frequency agree very well with experiment. The O22+, SO2+, SeO2+, and TeO2+ series show progressively decreasing exothermicities but similar barrier heights. The non-oxides, in contrast, show similar exothermicities but decreasing barriers with increasing size of the atom constituents. These trends are interpreted in terms of both valence bond curve-crossing and molecular orbital bonding models. The ozone dication, O32+, is found to have a number of low-lying singlet and triplet stationary state structures spanning near-linear to D3h2+ symmetries. Although the calculated exothermicity is even larger than for O22+, the barrier to O2+ + O+ dissociation is predicted to be low in each case. O22+ surrounded by six argon atoms to model an isolating environment shows increased equilibrium O–O bond length, decreased exothermicity, and increased barrier to dissociation, relative to the bare dication. O22+ flanked at each end by a perpendicularly oriented H2 molecule in a staggered conformation is obstructed from direct conversion to the water dimer dication by a high barrier. However, [(H2O)2]2+ dissociates smoothly from equilibrium to two water monocations with a large exothermicity but a small barrier. 相似文献
2.
When multimedia information is transported over a packet-switched network, the quality of presentation can be degraded due
to network delay variation or jitter. This paper presents a dejittering scheme that can be used in the transport of MPEG-4
and MPEG-2 video to absorb any introduced network jitter, thus preserving the presentation quality of transported media streams.
The dejittering scheme is based on the statistical approximation of delay variation in the arrival times of video packets
carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, a brief overview of the MPEG-4
system is presented. 相似文献
3.
In this work Substrate Induced Coagulation (SIC) was used to coat the cathode material LiCoO2, commonly used in Li-ion batteries, with fine nano-sized particulate titania. Substrate Induced Coagulation is a self-assembled dip-coating process capable of coating different surfaces with fine particulate materials from liquid media. A SIC coating consists of thin and rinse-prove layers of solid particles. An advantage of this dip-coating method is that the method is easy and cheap and that the materials can be handled by standard lab equipment. Here, the SIC coating of titania on LiCoO2 is followed by a solid-state reaction forming new inorganic layers and a core-shell material, while keeping the content of active battery material high. This titania based coating was designed to confine the reaction of extensively delithiated (charged) LiCoO2 and the electrolyte. The core-shell materials were characterized by SEM, XPS, XRD and Rietveld analysis. 相似文献
4.
A number of significant developments augur well for the future of psychoanalysis, both as a method of therapy and as a branch of psychological science. The contributions of Heinz Kohut, together with the explanations for his clinical findings as made possible by developmental psychology, cybernetics, communication science, and neurophysiology are reviewed in the context of their significance for Freud's pioneering discoveries. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Paul F. Basch 《Journal of chemical ecology》1986,12(8):1679-1686
An understanding of reproductive function is important for control of parasitic helminths. In cestodes and trematodes virtually nothing is known about regulatory and coordinating mechanisms that control maturation, gamete formation, egg production, and related processes. Neurosecretory neurons have been reported in various species but specific modes of action of neurohormones have yet to be demonstrated. The role of ecdysone is being investigated. 相似文献
6.
Fischer plots are plots of accommodation (derived by calculating cumulative departure from mean cycle thickness) versus cycle number or stratigraphic distance (proxies for time), for cyclic carbonate platforms. Although many workers have derived programs to do this, there are currently no published, easily accessible programs that utilize Excel. In this paper, we present an Excel-based spreadsheet program for Fischer plots, illustrate how the data are input, and how the resulting plots may be interpreted. The plots can be used to derive periods of increased accommodation, shown on the plots as a rising limb (which commonly matches times of more open marine, subtidal parasequence development). Times of decreased accommodation, shown on the plots as a falling limb, generally are coincident with thin, shallow, peritidal parasequences. 相似文献
7.
A. Stadler H.-J. Schimper U. BrendelD. Topa A. Basch H. Dittrich 《Thin solid films》2011,519(22):7951-7958
Exact, contact-free and non-destructive, optical analysis of semiconducting layers, are advantageous for thin film solar cell applications. A non-numerical theoretical model has been developed to extract approximation-free optical and electrical data from UV/Vis/NIR spectra. Special focus has been set on single layers; an adequate single-layer model is provided. Complex parameter evaluation is possible.This exact data acquisition model provides deeper insights in the process-parameter dependencies of pulsed direct current and radio frequency sputtered, opaque tin-sulphide thin films upon glass substrates. They have been analysed with respect to space-time dependencies of the sputter process. Therefore, sputter-depositions have been examined, referring to positions upon the substrate, r, target-substrate distances, dTarSub, and sputter durations, tSp. Theoretical sputter-concepts were proved and enhanced. Results were compared with those of the well-known Keradec/Swanepoel model. The necessity of taking both spectra—transmission and reflection spectra—into account has been shown.A non-contact, optical conductivity measurement possibility by use of UV/Vis/NIR spectroscopy has been provided. Optically evaluated conductivities, σL, were compared with electrically taken values, by use of a four-tip measurement system. 相似文献
8.
9.
Basch B. Moolenbeek R. Samalam V.K. Procanik M.J. 《Selected Areas in Communications, IEEE Journal on》1996,14(2):346-352
This paper describes the design of an OC-12c crossconnect switch developed for the VISTAnet research testbed and installed in GTE's Parkwood central office. The crossconnect switch has been designed as SONET-compliant line terminating equipment and provides switching for up to 16 OC-12c signals. The system consists of up to eight trunk interface cards with two bidirectional OC-12 ports, a synchronous switch card, and a control module with craft interface to provide service monitoring, provisioning, and maintenance functions. Several novel concepts, such as distributed power systems and integrated electro-optical backplane connectors, were incorporated in the design of the crossconnect. The system was implemented using a judicious mix of GaAs, ECL, and CMOS technology. Particular attention was given to equipping the crossconnect with extensive diagnostic capability to facilitate network performance monitoring. Graphic user interface technology provides an easy interface for either operator or maintenance personnel 相似文献
10.