基于相关性的中红外温度与发射率分离算法

温度和发射率是耦合在一起的.在精确获得大气参数的情况下,由传感器的辐射测量反演地表的温度与发射率,仍然是一个病态问题,必须采取一定的策略进行温度与发射率的分离.因此,温度与发射率的分离是红外遥感的核心问题.文章在分析无太阳直射光影响时大气下行辐射和含有大气残留的地表发射率之间关系的基础上,提出了一个针对野外测量中红外高光谱数据的温度与发射率分离算法.该算法利用大气下行辐射和含有大气残留的地表发射率之间的相关性作为判据来优化地表温度,进而获得地表发射率.基于模拟的中红外高光谱数据,对算法的精度进行评价.结果表明,该算法能够获得较高的地表温度和发射率反演精度;具有较广的适用范围,对测量过程中大气下行辐射变化不敏感;同时算法具有一定的抗噪性.     

Evidence for directp p interactions in the fragmentation channelp +α →p + pX at √s=88 GeV

We have investigated kinematical correlations between the outgoing beam proton and the proton emerging from the fragmentingα-particle inpα collisions at \(\sqrt {s_{p\alpha } } = 88GeV\) . Strong correlations are seen, indicating the dominance of quasi-elasticpp scattering in the fragmentation channelp+α→p+pX, for the ¦t¦ range 0.05–1.00 (GeV/c)². A Monte Carlo simulation of this process can explain the observed correlation spectra assuming an admixture of about 16% spectator protons.     

Electronic coupling in tetraanisylarylenediamine mixed-valence systems: the interplay between bridge energy and geometric factors

We have investigated three organic mixed-valence systems that possess nearly identical inter-redox site distances and differ by the nature of the bridging units benzene, naphthalene, and anthracene: the N,N,N',N'-tetra(4-methoxyphenyl)-1,4-phenylenene-diamine radical cation (1+), the 1,4-bis(N,N-di(4-methoxyphenyl)-amino)naphthalene radical cation (2+), and the 9,10-bis(N,N-di(4-methoxyphenyl)amino)anthracene radical cation (3+). The electronic interactions in these systems have been studied by means of gas-phase ultraviolet photoelectron spectroscopy, vis/NIR spectroscopy, and electronic-structure calculations. The experimental and theoretical results concur to indicate that the strength of electronic interaction decreases in the following order of bridging units: benzene > naphthalene > anthracene. This finding contradicts the usual expectation that anthracene is superior to benzene as a driving force for electronic communication. We explain these results in terms of a super-exchange mechanism and its strong dependence on steric interactions.     

Electronic structure of bent titanocene complexes with chelated dithiolate ligands

Gas-phase photoelectron spectroscopy and density functional theory have been utilized to investigate the interactions between the p orbitals of dithiolate ligands and d orbitals of titanium in bent titanocene complexes as minimum molecular models of active site features of pyranopterin Mo/W enzymes. The compounds Cp(2)Ti(S-S) [where (S-S) is 1,2-ethenedithiolate (S(2)C(2)H(2)), 1, 1,2-benzenedithiolate (bdt), 2, or 1,3-propanedithiolate (pdt), 3, and Cp(-) is cyclopentadienyl] provide access to a formal 16-electron d(0) electronic configuration at the metal. A "dithiolate-folding-effect" involving an interaction of metal and sulfur orbitals is demonstrated in complexes with arene- and enedithiolates. This effect is not observed for the alkanedithiolate in complex 3.     

FLUORESCENCE ENERGY TRANSFER BETWEEN DIMETHYLDIAZAPEROPYRENIUM DICATION AND ETHIDIUM INTERCALATED IN POLY d(A-T)

Dimethyldiazaperopyrenium is one of the largest known DNA intercalators. Fluorescence energy transfer occurred between dimethyldiazaperopyrenium (donor) and ethidium (acceptor) when these dyes were bound to a double-stranded polynucleotide such as poly d(A-T). The addition of increasing amounts of ethidium bromide led to a marked shortening of the fluorescence lifetime of the donor, whereas the excited state of the acceptor was progressively populated via energy transfer from the donor. Critical Förster distance between these two chromophores was calculated to be 3.8 nm. The observed transfer efficiency was lower than that calculated on the basis of this critical distance and a statistical distribution of bound drugs. These results are discussed taking into account the conformational change induced by intercalation of dimethyldiazaperopyrenium in the double-stranded polynucleotide.     

Photoelectron spectroscopy of bis(2,4-pentanedione)-oxovanadium(IV) [VO(acac)(2)] and derivatives: substituent effects on the 2,4-pentanedione donor

The electronic structure of derivatives of VO(acac)(2) is probed using gas-phase UV-photoelectron spectroscopy [acac = 2,4-pentanedione]. The effect on the metal center of electron-donating and -withdrawing groups on the acac ligands is examined. Ionizations from metal-based, acac-based, and V=O-based orbitals are clearly observed. We find that changes at the ligand periphery lead to equivalent changes in the energies of the metal-based and ligand-based ionizations. Additionally, we find that a linear correlation exists between the ionization energies of the metalated complexes and the pK(a) values of the free ligands, indicating that the pK(a) is a good indication of the overall electron-donating abilities of acac ligands.     

PHOTODYNAMIC INHIBITION OF ESCHERICHIA COLI DNA POLYMERASE I BY 8-METHOXYPSORALEN PLUS NEAR ULTRAVIOLET IRRADIATION

Abstract— Morphological abnormality due to the UV irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pukherrimus. When sperm was UV-irradiated and allowed to fertilize unirradiated eggs, the effect of the UV was manifested as an abnormal morphology of embryos in the gastrula or later stages. The UV-induced morphological abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. In the experiments on a stage-dependent change of PR effectiveness, it was found that an illumination sufficed to effect a nearly complete PR when applied up to the onset of the first DNA synthetic phase, while the PR effectiveness declined thereafter. Illumination after the completion of DNA synthesis had little effect for PR.     

The Electronic Structure and Bonding of the First p-Block Paddlewheel Complex,Bi<Subscript>2</Subscript>(trifluoroacetate)<Subscript>4</Subscript>, and Comparison to d-Block Transition Metal Paddlewheel Complexes: A Photoelectron and Density Functional Theory Study

The photoelectron spectrum and a density functional computational analysis of the first p-block paddlewheel complex, Bi₂(tfa)₄, where tfa = (O₂CCF₃)⁻, are reported. The photoelectron spectrum of Bi₂(tfa)₄ contains an ionization band between the region of metal-based ionizations and the region of overlapping ligand ionizations that is not seen in the photoelectron spectra of d-block paddlewheel complexes. This additional ionization arises from an a_1g symmetry combination of the tfa ligand orbitals that is directed for σ bonding with the metals, and the unusual energy of this ionization follows from the different interaction of this orbital with the valence s and p orbitals of Bi compared to the valence d orbitals of transition metals. There is significant mixing between the Bi–Bi σ bond and this a_1g M–L σ orbital. This observation led to a re-examination of the ionization differences between Mo₂(tfa)₄ and W₂(tfa)₄, where the metal–metal σ and π ionizations are overlapping for the Mo₂ molecule but a separate and sharp σ ionization is observed for the W₂ molecule. The coalescing of the σ and π bond ionizations of Mo₂(tfa)₄ is due to greater ligand orbital character in the Mo–Mo σ bond (∼7%) versus the W–W σ bond (∼1%). In tribute to F. Albert Cotton for sharing the beauty of symmetry and the joy and excitement in the exploration of metal–metal bonds.     

多约束水平运输问题的时间费用均衡

基于为顾客提供最佳服务的现代营销理念,剖析了从一定产地到一定销地所发生的运输问题,构建了时间用均衡的目标模式及多目标约束水平MC^2运输问题的数学模型,本文在建立一系列定义,定理的基础上,提出了认明时间费用均衡解空间的优化决策方法,并结合示例展现了这一方法在解决客观实际问题中的有效性。