Multiple doping structures of the rare-earth atoms in ß-SiAlON:Ce phosphors and their effects on luminescence properties.

The critical doping structures of rare-earth atoms in the promising ß-SiAlON phosphors have long been argued owing to the lack of direct evidence. Here, the exact locations and coordination of the Ce rare-earth atoms in the ß-SiAlON structure have been examined using an atom-resolved Cs-corrected scanning transmission electron microscope. Three different occupation sites for the Ce atoms have been directly observed: two of them are in the structural channel coordinated with six and nine N(O) atoms, respectively; the other one is the unexpected substitution site for Si(Al). The chemical valences and stabilities of the doping Ce ions at the different occupation sites have been evaluated using density functional calculations. Correlation of the different doping structures with the luminescence properties has been investigated by the aid of cathodoluminescence (CL) microanalysis, which verifies the different contribution of the interstitial trivalent Ce ions to the light emission while no luminescence is observed for the substitutional doping of quadrivalent Ce.

The effect of micro-environment on luminescence of aequorin: the role of amino acids and explicit water molecules on spectroscopic properties of coelenteramide.

Despite the fact that the luminescence reaction mechanism of aequorin has been intensively investigated, details in luminescence such as the effect of important amino acids residues and explicit water molecules on spectroscopic properties of coelenteramide remain unclear. In this work, the effect of amino acids residues His16, Tyr82, Trp86, Phe113, Trp129, Tyr132, explicit water molecules Wat505 and Wat405 on the spectral properties of CLM(-) has been studied by CAM-B3LYP, TD M06L and TD CAM-B3LYP methods in hydrophobic environment and aqueous solution. In hydrophobic environment, the amino acids or water molecules have no significant effect on the absorption. Tyr82 and Trp86 move close to CLM(-) changes the hydrogen bond network, and thus, the spectral properties is significantly affected by the hydrogen bonds between His16H(+)+Tyr82+Trp86 and CLM(-). Tyr82, Trp86 hydrogen bonding to CLM(-) upshifts the excited energy and helps emission spectra shift to blue region. Therefore, it is concluded that His16H(+)+Tyr82+Trp86 modify the emission spectra. The molecular electrostatic potential indicated that the greater electron density is located at the oxygen atom of 6-p-hydroxyphenyl group of CLM(-), and it facilitates the formation of hydrogen bond with His16H(+)+Tyr82+Trp86. It is a critical condition for the modification of emission spectra. It is expected to help to understand the interactions between emitter and amino acids in the micro environment.

The dynamics simulation and quantum calculation investigation about luminescence mechanism of coelenteramide.

The dynamics simulation and quantum chemical calculation are employed to investigate spectrum properties of deprotonation process of coelenteramide and two final states neutral state and phenolate anion. According to the calculation results, theoretical evidence supporting the luminescence mechanism hypothesis is proposed in a significant bioluminescence process. In vivo of marine bioluminescent organisms, if the protein motion provides the conditions for the deprotonation of coelenteramide in some protein molecules, the phenolate anion is completely deprotonated coelenteramide as an emitter in these protein molecules and emits fluorescence assigned to the lower energy peak. And in another emitter in which the condition of deprotonation is not met, the fluorescence is produced by the neutral state of coelenteramide and assigned to the higher energy peak. The energy difference decreases gradually when the proton of coelenteramide gradually approaches to His22. For phenolate anion and neutral state, electronic cloud distributions between their each frontier molecular orbitals HOMO and LUMO have high overlapping volume. The molecular electrostatic potential indicates that for phenolate anion, the oxygen atom after deprotonation has greater electron density, which is good for formation hydrogen bonds with amino acids in the environment.

[Cloning of full-length coding sequence of tree shrew CD4 and prediction of its molecular characteristics].

The tree shrews, as an ideal animal model receiving extensive attentions to human disease research, demands essential research tools, in particular cellular markers and monoclonal antibodies for immunological studies. In this paper, a 1 365 bp of the full-length CD4 cDNA encoding sequence was cloned from total RNA in peripheral blood of tree shrews, the sequence completes two unknown fragment gaps of tree shrews predicted CD4 cDNA in the GenBank database, and its molecular characteristics were analyzed compared with other mammals by using biology software such as Clustal W2.0 and so forth. The results showed that the extracellular and intracellular domains of tree shrews CD4 amino acid sequence are conserved. The tree shrews CD4 amino acid sequence showed a close genetic relationship with Homo sapiens and Macaca mulatta. Most regions of the tree shrews CD4 molecule surface showed positive charges as humans. However, compared with CD4 extracellular domain D1 of human, CD4 D1 surface of tree shrews showed more negative charges, and more two N-glycosylation sites, which may affect antibody binding. This study provides a theoretical basis for the preparation and functional studies of CD4 monoclonal antibody.

[Cloning of full-length coding sequence of tree shrew CD3E and prediction of its molecular characteristics].

The use of tree shrews (Tupaia belangeri) in human disease studies demands essential research tools, in particular cellular markers and their monoclonal antibodies for immunological studies. Here we cloned the full-length cDNAs encoding CD3E from total RNA of the spleen, liver and peripheral blood of tree shrews and analyzed their structural characteristics in comparison with other mammals by Discovery Studio software. The results showed that the open reading frame sequence of tree shrew CD3E was 582 bp, encoding 194 amino acids. The overall structure of tree shrew CD3E protein was similar to its counterparts of other mammals, intracellular and transmembrane domain highly conserved. However, detailed analysis revealed two potential glycosylation sites and different surface charges in the extracellular domain. Availability of the entire open-reading-frame and related sequence information would therefore facilitate the preparation of monoclonal antibodies against tree shrew CD3 and further studies for its function.

Theoretical Investigation of the Reaction of Imidogen with Fulminic Acid.

The mechanism of the reaction of imidogen (NH) with fulminic acid (HCNO) has been investigated theoretically using the multiconfigurational self-consistent-field theory (MCSCF), multireference Rayleigh-Schrodinger perturbation theory (RSPT2), and coupled cluster theory (CC) along with the complete basis set extrapolations (CBS). The calculations show that the NH + HCNO reaction takes place via an N → C addition mechanism predominantly by surmounting a small barrier (ca. ∼3 kcal/mol). The adduct is HC(NH)NO in the triplet state with an exothermicity of more than 60 kcal/mol. The subsequent C-N cleavage, which is nearly barrierless, leads to HCNH and NO as the final products. This represents the most energetically favorable product channel of the title reaction. The channels leading to HCN, HNC, HNO, or HON via O- or H-migration mechanisms involve higher barriers and thus are negligible. The singlet-triplet crossing has been investigated as well for the HCNH + NO product channel by locating the conical interactions. Using transition state theory, the rate constants were predicted as a function of temperatures. It is suggested that the NH + HCNO reaction might be an alternative source for the NO regeneration under the combustion conditions. This calculation is useful to simulate experimental investigations of the NH + HCNO reaction.

[Salmonella choleraesuis C500 delivering DNA immunization against classical swine fever virus].

Classical Swine Fever Virus (CSFV) E2 protein eukaryotic expression plasmid pVAXE2 was constructed. The plasmid pVAXE2 was transformed into Salmonella choleraesuis C500 (S. C500) attenuated vaccine strain by electroporation to generate Salmonella choleraesuis engineering strain S. C500/pVAXE2. The characterization of S. C500/pVAXE2 in morphology, growth, biochemistry and serology indicated that it retained the same properties as its original strain S. C500 with exception of kanamycin resistance originated from the plasmid pVAXE2. The plasmid stable in the bacteria after 15 passages. Kunming mice and rabbits were vaccinated three times at two weeks interval with S. C500/pVAXE2 in oral and intramuscular routes at the dosage of 1 x 10(8) CFU for mice and 2 x 10(9) CFU for rabbits each time. The specific antibody response against CSFV and Salmonella choleraesuis was detected by ELISA. Two weeks after the third boost the immunized rabbits were challenged with 20 ID50 of hog cholera lapinized virus (HCLV), followed by a virulent strain of Salmonella choleraesuis two week later than HCLV challenge. The results showed that all immunized mice and rabbits produced significant antibodies against CSFV and Salmonella choleraesuis, and the immunized rabbits demonstrated the effective protection against the challenge of HCLV and virulent Salmonella choleraesuis. These results indicated the potential of developing multiplex swine DNA vaccine by using this bacteria as the vector.