Lifschitz singularities for periodic operators plus random potentials

UsingX-bounding (lower bounds by Laplacians with mixed boundary conditions and discrete analogs), we obtain the Lifschitz exponent at the bottom of the spectrum for random operators of typeH =T+V , withT a (periodic) generator of a positivity-preserving semigroup, extending results by Kirsch and Simon.     

Anti-metatype antibodies in immunoassays

In this review anti-metatype antibodies are described invoking new principles in immunoassay development. Anti-metatype antibodies are immunological reagents specific for the conformation of the liganded antibody active site which do not interact with bound ligand or unliganded antibody. Relationships between anti-metatype antibody reactivity and the ligand-induced conformational state of monoclonal antibodies are reviewed with emphasis on the fluorescein hapten as a small molecule model system. One characteristic result of the interaction of anti-metatype antibodies with liganded antibodies is a significant delay in the dissociation rate (k₂) of the ligand bound within the primary immune complex. The latter is an important consideration for assay development. Polyclonal and monoclonal anti-metatype antibody reagents are characterized in terms of their differential effects on the ligand dissociation rate. Anti-metatype antibody reactivity is further discussed in terms of protein-protein specificity patterns and relative interactions with idiotype-family members, structural derivatives, and site-specific mutants. Incorporation of principles inherent in the anti-metatype concept and their application to assay development are summarized.Abbreviations D₂O deuterium oxide - Fab 50 kd antibody fragment containing V_HC_H1 + V_LC_L domains - FITC(I) fluorescein isothiocyanate (isomer I) - Fv 26 kd fragment of the antibody molecule containing the variable domains of the H and L chains - Ig immunoglobulin - IgG immunoglobulin G with a mol. wt. of 150 kd. - IgM immunoglobulin M with a mol. wt. of 10⁶d - Id idiotype - Ka antibody affinity (k₁/k₂) in M^–1 - k₁ second order rate of ligand association in M^–1s^–1 - k₂ first order rate of ligand dissociation in s^–1 - K_D dissociation constant or the reciprocal of the affinity constant (1/Ka) - Mab monoclonal antibody - Met metatype - NMR nuclear magnetic resonance - SCA single chain Fv derivative containing a synthetic linker between the two variable domains - V_H variable domain of the antibody H chain - V_L variable domain of the antibody L chain     

Dynamics of intramolecular processes in electronic-excited states of 2,4,5-triarylimidazole molecules

Intramolecular processes in electronic-excited states of 2,4,5-triarylimidazole molecules were studied by femtosecond laser spectroscopy. Experiments were carried out with two types of compounds, namely, those experiencing intramolecular proton transfer and two model compounds in which it is impossible. Schemes of the processes studied were proposed and the characteristic rate constants were determined. The excited-state intramolecular proton transfer (ESIPT) in the molecules with planar structure of the reaction center is a very fast process (100 fs). If the reaction center has a nonplanar structure and, hence, the intramolecular hydrogen bond is weakened, the ESIPT time is determined by the time of conformational rearrangement of the molecule.     

NH_2基态和激发态的SAC－CI和量子拓扑方法研究

ＮＨ_２基态和激发态的ＳＡＣ－ＣＩ和量子拓扑方法研究郑世钧，蔡新华，宋天乐，孟令鹏，中迁博，波田雅彦（河北师范学院化学系，石家庄，０５００９１）（京都大学工程学院京都，日本）关键词ＳＡＣ－ＣＩ方法，激发态，电子密度，拓扑分析用量子拓扑学方法研究激发态...     

In search of new resonance structures in dissociative photoionization of H2

We present a theoretical study of dissociative photoionization of H₂ via the ¹Π_u symmetry in the photon energy range 30–43 eV. Our results explain the various peaks observed in the experiments below 40 eV and illustrate, in particular, the important role of the ²Π_u(2pπ_u) ionization threshold. At higher photon energies, they suggest the existence of new resonance structures that may be associated with doubly excited states of H₂ lying above the third and fourth ionization thresholds (the Q₃ and Q₄ resonance series). From the calculated resonance parameters, we conclude that the dominant mechanism at high photon energies should involve the Q₄ (and probably higher) doubly excited states of H₂. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2002     

Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li_2H

A 285-pomt multi-reference configuration-interaction involving single and double excitations ( MRS DCI) potential energy surface for the electronic ground state of L12H is determined by using 6-311G (2df,2pd)basis set.A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a x2 of 4.64×106 The equn librium geometry occurs at Rc=0.172 nm and,LiHL1=94.10°.The dissociation energy for reaction I2H(2A)→L12(1∑g)+H(2S) is 243.910 kJ/mol,and that for reaction L12H(2A')→HL1(1∑) + L1(2S) is 106.445 kl/mol The inversion barrier height is 50.388 kj/mol.The vibrational energy levels are calculated using the discrete variable representation (DVR) method.     

Internally contracted multiconfiguration-reference configuration interaction calculations for excited states

Summary The calculation of electronically excited states with the internally contracted multiconfiguration-reference configuration interaction (CMRCI) method is discussed. A straightforward method, in which contracted functions for all states are included in the basis, is shown to be very accurate and stable even in cases of narrow avoided crossings. However, the expense strongly increases with the number of states. A new method is proposed, which employs different contracted basis sets for each state, and in which eigensolutions of the Hamiltonian are found using an approximate projection operator technique. The computational effort for this method scales only linearly with the number of states. The two methods are compared for various applications.Dedicated in honor of Prof. Klaus Ruedenberg