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61.
A. Mañanes M. Membrado J. Sañudo A. F. Pacheco L. C. Balbás 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,19(4):55-58
An analytic expression for the total energy of metallic clusters composed ofN identical atoms of valencev and with net chargeQ is obtained by means of a variational solution of the Thomas-Fermi-Weizsäcker energy density functional within the spherical jellium model. The minimum energy is given as an expansion in decreasing powers of the cluster radiusR=r s Z 1/3, withZ=vN andr s the radius per electron of the bulk metal. The coefficients are obtained as functions ofr s . Terms of volume (R 3), surface (R 2), curvature (R), constant (R 0), (1/R) and (1/R 2) are clearly separated in the formula, as well as the different contributions (kinetic, coulombic and exchange-correlation) to each of them. The asymptotic values (R→∞) for the work functions,W(r s ), and surface energies σ(r s ), are compared to analogous semiclassical and Kohn-Sham calculations of jellium-like surfaces and to the experimental values. The size dependent behaviour of chemical potentials, μ(R), electron affinities,AF(R), and ionization potentials,IP(R), are easily obtained for any kind of metallic clusters. In particular we discuss the Coulomb and quantum corrections to the coefficients β, δ in the asymptotic formulae:IP?W+β/R andAF?W+δ/R. 相似文献
62.
63.
Jung HW La SJ Kim JY Heo SK Kim JY Wang S Kim KK Lee KM Cho HR Lee HW Kwon B Kim BS Kwon BS 《Experimental & molecular medicine》2003,35(6):501-508
Herpes virus entry mediator (HVEM) is a newly discovered member of the tumor necrosis factor receptor (TNFR) superfamily that has a role in herpes simplex virus entry, in T cell activation and in tumor immunity. We generated mAb against HVEM and detected soluble HVEM (SHVEM) in the sera of patients with various autoimmune diseases. HVEM was constitutively expressed on CD4(+) and CD8(+) T cells, CD19(+) B cells, CD14(+) monocytes, neutrophils and dendritic cells. In three-way MLR, mAb 122 and 139 were agonists and mAb 108 had blocking activity. An ELISA was developed to detect sHVEM in patient sera. sHVEM levels were elevated in sera of patients with allergic asthma, atopic dermatitis and rheumatoid arthritis. The mAbs discussed here may be useful for studies of the role of HVEM in immune responses. Detection of soluble HVEM might have diagnostic and prognostic value in certain immunological disorders. 相似文献
64.
The surface species resulting in exposing of the ZSM-5 zeolite at elevated temperatures to methanol, deuterated methanol or ethylene have been studied by IR method.The three-step adsorption at 150°, 300°, 420° C or one-step adsorption at 420° C have been carried out in order to prepare the samples for IR. In all cases the most prominent band appeared in the range 1495–1515 cm?1; besides two bands at about 1470 and 1370 cm?1 have been observed. On the basis of Greenler's results and of the shift values of the bands in our spectrum of adsorbed deuterated methanol it was supposed that the band 1495–1515 cm?1 is due to the OCO group from the surface species. Moreover these species would involve both oxygen atoms from the surface of zeolite but not from OH groups of methanol. 相似文献
65.
A new complex [Ni(en)3]4[HVⅣ12VⅤ6O42(PO4)] has been hydrothermally synthesized and characterized by X-Ray diffraction, IR and Elemental analysis. Single crystal X-ray analysis indicates that this compoud crystallizes in cubic system,space group Im 3m with a=17.4081(2)?, V=5275.38(10)?3, R=0.0420, wR=0.1055, Z=2, Dc=1.663g·cm-3, μ=2.297mm-1, F(000)=2636. The crystal structure consists of [Ni(en)3]2+ cations and {HV18O42(PO4)}8- cluster anion which construct from 18 {VO5} square pyramids. The VO5 pyramids joined each other to form a {V18O42} cage hosting a tetrahedral {PO4}3- moiety with disordered oxygen atoms. CCDC: 185574. 相似文献
66.
67.
Alvarez CM Alvarez MA García-Vivó D García ME Ruiz MA Saáez D Falvello LR Soler T Herson P 《Dalton transactions (Cambridge, England : 2003)》2004,(24):4168-4179
The new hydride complexes [Mo2Cp2(mu-H)(mu-PHR)(CO)4] having bulky substituents (R = 2,4,6-C(6)H2tBu3= Mes*, R = 2,4,6-C6H2Me3= Mes) have been prepared in good yield by addition of Li[PHR] to the triply bonded [Mo2Cp2(CO)4] and further protonation of the resulting anionic phosphide complex [Mo2Cp2(mu-PHR)(CO)4]-. Protonation of the Mes* compound with either [H(OEt2)2][B{3,5-C6H3(CF3)2}4] or HBF4.OEt2 gives the cationic phosphinidene complex [Mo2Cp2(mu-H)(mu-PMes*)(CO)4]+ in high yield. In contrast, protonation of the analogous hydride compounds with Mes or Cy substituents on phosphorus give the corresponding unsaturated tetracarbonyls [Mo2Cp2(mu-PHR)(CO)4]+, which are unstable at room temperature and display a cis geometry. Decomposition of the latter give the electron-precise pentacarbonyls [Mo2Cp2(mu-PHR)(mu-CO)(CO)4]+, also displaying a cis arrangement of the metal fragments. In the presence of BF4- as external anion, fluoride abstraction competes with carbonylation to yield the neutral fluorophosphide hydrides [Mo2Cp2(mu-H)(mu-PFR)(CO)4]. Similar results were obtained in the protonation reactions of the hydride compounds having a Ph substituent on phosphorus. In that case, using HCl as protonation reagent gave the chloro-complex [Mo2ClCp2(mu-PHPh)(CO)4] in good yield. The structures and dynamic behaviour of the new compounds are analyzed on the basis of solution IR and 1H, 31P, 19F and 13C NMR data as well as the X-ray studies carried out on [Mo2Cp2(mu-H)(mu-PHMes)(CO)4](cis isomer), [Mo2Cp2(mu-H)(mu-PFMes)(CO)4](trans isomer), [Mo2Cp2(mu-PHCy)(mu-CO)(CO)4](BF4) and [Mo2ClCp2(mu-PHPh)(CO)4]. 相似文献
68.
A simple and rapid densitometric method has been developed for the simultaneous determination of amoxycillin trihydrate and clavulanate potassium in pharmaceutical preparations. After extraction of the analytes with distilled water, the extracts were spotted on precoated silica gel plates, which were then eluted with butyl acetate-methanol-glacial acetic acid-water (15 + 7.5 + 7.5 + 3, v/v). Quantitative evaluation was performed by measuring the absorbance reflectance of the analyte spots at lambda = 240 nm. The densitometric method is rapid, selective, precise, and accurate and, thus, can be used for routine analysis of pharmaceutical preparations in quality control laboratories of the pharmaceutical industry. 相似文献
69.
Two new complexes (Cp)2Ti(Sal)2 and(Cp)2Ti(Clo)2(Cp=Cyclopentadienyl η5-C5H5), have been synthesized in anhydrous THF by the reaction of Hsal(o-hydroxybenzoic acid, salicylate acid) or Hclo[N-(m-chloro-phe-nyl) anthranili acid, acidum clofenamicum] with (Cp)2TiCl2 and characterized by means of elemental analyses, IR, 1H NMR, 13C NMR, UV and molar conductivity. In complex (Cp)2Ti(Sal)2 or (Cp)2Ti(Clo)2, the oxygen atom of the carboxyl group coordinates to Ti(IV) in a monodentate manner. The inhibitory action of the complexes on mouse ear tumefaction caused by croton oil and rat foot granulation growth caused by cotton balls is higher than that of the corresponding ligands Hsal, Hclo and [(Cp)2TiCl2], whereas their toxicity is lower than those of the free ligands. 相似文献
70.
He Ping ZENG 《中国化学快报》2002,13(12)
Photoinduced electron transfer processes between fullerenes (C60 / C70) and N, N, N′, N′- tetra - ( p-methylphenyl ) - 4, 4′- diamino - 1, 1′- diphenyl ether ( TPDAE ) have been studied by nanosecond laser flash photolysis. Quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C60 / C70 ) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state, radical anion of fullerenes ( C60 / C70 ) and radical cations of TPDAE appear. 相似文献