排序方式: 共有52条查询结果,搜索用时 31 毫秒
41.
G. J. Gounaris J. Layssac J. E. Paschalis F. M. Renard 《Zeitschrift fur Physik C Particles and Fields》1995,66(4):619-632
We compute the helicity amplitudes for bosonboson scattering at high energy due to the operatorsO BΦ,O WΦ andO UB , and we derive the corresponding unitarity bounds. Thus, we provide relations between the couplings of these operators and the corresponding New Physics thresholds, where either unitarity is saturated or new degrees of freedom are excited. We compare the results with those previously obtained for the operatorsO W andO UW and we discuss their implications for direct and indirect tests at present and future colliders. The present treatment completes the study of the unitarity constraints for all blind bosonic operators. 相似文献
42.
Karanikolos GN Alexandridis P Itskos G Petrou A Mountziaris TJ 《Langmuir : the ACS journal of surfaces and colloids》2004,20(3):550-553
A scalable method for controlled synthesis of luminescent compound semiconductor nanocrystals (quantum dots) using microemulsion-gas contacting at room temperature is reported. The technique exploits the dispersed phase of a microemulsion to form numerous identical nanoreactors. ZnSe quantum dots were synthesized by reacting hydrogen selenide gas with diethylzinc dissolved in the heptane nanodroplets of a microemulsion formed by self-assembly of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) amphiphilic block copolymer in formamide. A single nanocrystal is grown in each nanodroplet, thus allowing good control of particle size by manipulation of the initial diethylzinc concentration in the heptane. The ZnSe nanocrystals exhibit size-dependent luminescence and excellent photostability. 相似文献
43.
Using the Hartree-Fock method the wave functions of Li+, Be2+, O2–, F–, Na+, Mg2+, Al3+, S2–, Cl–, K+, Ca2+, Sc3+ and Ti4+ have been calculated for the free ion and the ion in a potential well. The main result of these calculations is a contraction of the anion and an expansion of the cation due to the external potential. A comparison of the calculations with an experimental determination of the electron density distribution in NaCl and MgO shows qualitative agreement. The diamagnetic susceptibility , the dipole polarizability d, and the Sternheimer antishielding factor of the ions given above were also calculated for the free ions and the spherical potential ions (SPI). The charged hollow sphere model improves the theoretical values towards the properties determined by experiment.
D 17 (E. Paschalis, 1967). 相似文献
Zusammenfassung Unter Verwendung der Hartree-Fock-Methode wurden analytische Wellenfunktionen für die Ionen Li+, Be2+, O2–, F–, Na+, Mg2+, Al3+, S2–, Cl–, K+, Ca2+, Sc3+ und Ti4+ berechnet. Es wurden sowohl die freien Ionen als auch Ionen im Potentialtopf untersucht. Es zeigt sich eine durch das äußere Potential hervorgerufene Kontraktion der Anionen und eine Expansion der Kationen. Der Vergleich der Rechnungen mit experimentellen Bestimmungen der Elektronendichteverteilung in NaCl und MgO zeigt qualitative Übereinstimmung zwischen Theorie und Experiment. Ferner wurden die diamagnetische Suszeptibilität , die Dipolpolarisierbarkeit d und der Antishieldingfaktor (Sternheimerfaktor) sowohl für die freien als auch für die durch ein kugelsymmetrisches Potential gestörten Ionen berechnet. Das hier benutzte Festkörpermodell der geladenen Hohlkugel ergibt Werte, die in guter Übereinstimmung mit dem Experiment sind.
Résumé Les fonctions d'onde de Li+, Be2+, O2–, F–, Na+, Mg2+, Al3+, S2–, Cl–, K+, Ca2+, Sc3+ et Ti4+ ont été calculées par la méthode de Hartree-Fock pour l'ion libre et pour l'ion dans un puit de potentiel. Le résultat essentiel de ces calculs montre une contraction de l'anion et une expansion du cation sous l'effet du potentiel extérieur. Les densités électroniques calculées et celles obtenues expérimentalement dans NaCl et MgO sont en accord qualitatif. La susceptibilité diamagnétique , la polarisabilité dipolaire d, et le facteur anti-écran de Sterneimer des ions ci-dessus ont été calculés pour les ions libres et pour les ions à «potentiel sphérique» (SPI). Le modèle de la sphère creuse chargée améliore les valeurs théoriques par rapport aux données expérimentales.
D 17 (E. Paschalis, 1967). 相似文献
44.
Docoslis A Espinoza LA Zhang B Cheng LL Israel BA Alexandridis P Abbott NL 《Langmuir : the ACS journal of surfaces and colloids》2007,23(7):3840-3848
Nonuniform ac (alternating current) electric fields created by microelectrodes are investigated for their influence on the transport of the vesicular stomatitis virus (VSV) from aqueous suspensions of physiological ionic strength to surfaces on which the VSV is captured. Whereas passive diffusion did not lead to detectable levels of virus captured on a surface when using titers of VSV as high as 107 PFU/mL, nonuniform electric field-mediated transport led to the detection of 105 PFU/mL of virus in 2 min. An order-of-magnitude analysis of the time scales associated with virus transport to the microelectrodes inside media of physiological relevance indicates that electrothermal fluid flow (and the resulting viscous drag forces on the virus) rather than dielectrophoresis likely constitutes the major mechanism for virus transport far from the electrodes. The influence of dielectrophoresis was calculated to be confined to a region within a few micrometers of the electrodes and to lead to collection patterns of both virus and fluorescently labeled particles near the electrodes that were found to be in qualitative agreement with experiments. These observations and conclusions are discussed within a theoretical framework presented in the paper. The results presented in this work, when combined, suggest that ac electrokinetic phenomena can be used to expeditiously transport and capture viruses onto surfaces from solutions of high ionic strength, thus providing a potentially useful approach to addressing a bottleneck in the development of devices that allow for rapid sampling and detection of infectious biological agents. 相似文献
45.
Manos Gkikas Jaakko Timonen Janne Ruokolainen Paschalis Alexandridis Hermis Iatrou 《Journal of polymer science. Part A, Polymer chemistry》2013,51(6):1448-1456
A facile strategy is developed to synthesize Au nanoparticles (Au‐NPs) using water‐soluble poly(L ‐proline) (PLP). The synthesized NPs were characterized by TEM, FTIR and NMR spectroscopy, thermogravimetric analysis, and circular dichroism. It was found that PLP has a “dual” role as an efficient reductant of Au(III) and simultaneously as a stabilizing agent of Au‐NPs. The influence of PLP molecular weight, temperature, initial Au(III) concentration, and Au(III)/PLP molar ratio on the size and dispersity of Au‐NPs is examined. It was found that the unique extended secondary structure of PLP II resulted in the facile formation of highly crystalline Au‐NPs in water at a very low Au(III)/PLP molar ratio. These Au‐NPs have the smallest dimensions and size distributions among NPs synthesized so far by polymeric materials in aqueous media, and exhibit enduring colloidal stability. Therefore, by utilizing biocompatible and benign materials in water, we managed to obtain Au‐NPs, so as the final product is ready‐to‐use for biomedical applications. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
46.
Eleftheria Antoniou Efrosyni Themistou Biswajit Sarkar Marina Tsianou Paschalis Alexandridis 《Colloid and polymer science》2010,288(12-13):1301-1312
The structure and dynamics of the common polysaccharide dextran have been investigated in mixed solvents at two different temperatures using small-angle X-ray scattering (SAXS) and viscosity measurements. More specifically, binary mixtures of a good solvent (water, formamide, dimethylsulfoxide, ethanolamine) and the bad solvent ethanol as the minority component have been considered. The experimentally observed effects on the polymer conformation (intrinsic viscosity, coil radius, and radius of gyration) of the bad solvent addition are discussed in terms of hydrogen bonding density and are correlated with the Hansen solubility parameters and the surface tension of the solvent mixtures. Hydrogen bonding appears to be an important contributor to the solubility of dextran but is not sufficient to capture the dextran coil contraction in the mixtures of good+bad solvents. 相似文献
47.
Wiedeking M Bernstein LA Krtička M Bleuel DL Allmond JM Basunia MS Burke JT Fallon P Firestone RB Goldblum BL Hatarik R Lake PT Lee IY Lesher SR Paschalis S Petri M Phair L Scielzo ND 《Physical review letters》2012,108(16):162503
A new experimental technique is presented using proton-γ-γ correlations from (94)Mo(d,p)(95)Mo reactions which allows for the model-independent extraction of the photon strength function at various excitation energies using primary γ-ray decay from the quasicontinuum to individual low-lying levels. Detected particle energies provide the entrance excitation energies into the residual nucleus while γ-ray transitions from low-lying levels specify the discrete states being fed. Results strongly support the existence of the previously reported low-energy enhancement in the photon strength function. 相似文献
48.
Dimopoulos P Athlan A Manaviazar S George J Walters M Lazarides L Aliev AE Hale KJ 《Organic letters》2005,7(24):5369-5372
[reaction: see text] The O-directed hydrostannation of various propargyloxy substrates is reported with Ph(3)SnH/Et(3)B. 相似文献
49.
S. Ilieva O. Kiselev H. Emling P. Egelhof K. Boretzky J. P. Meier H. Simon K. Mahata T. Le Bleis A. Chatillon F. Aksouh K. Beckert P. Beller C. Kozhuharov Y. Litvinov X. C. Le F. Nolden M. Steck T. Stöhlker G. Ickert U. Popp H. Weick D. Rohe J. Jourdan D. Werthmüller H. Moeini A. Zalite S. Paschalis 《The European physical journal. Special topics》2007,150(1):357-358
The investigation of light-ion induced direct reactions
in inverse kinematics, using stored and cooled radioactive beams,
interacting with internal H, He, etc. gas-jet targets, bears a large
potential for nuclear structure and astrophysics studies on exotic
nuclei. An extended research project EXL has been accepted for the
future facility FAIR in Darmstadt, Germany. In order to explore the
experimental conditions for measurements planned at FAIR, a first
test experiment for proving the feasibility of the EXL concept was
performed. 相似文献
50.
Treating light as well as heavy pseudoscalar and vector mesons as non-relativistic quarkonia, we calculate various decay modes, including lowest QCD corrections. All decay modes studied are in good agreement with experiment, indicating that the quarkonium treatment is applicable to light mesons η, η′, π, also. Consistency of the quarkonium and current algebra treatments for the process π0 → 2λ leads to is the constituent u-quark mass, and . 相似文献