Site-specific vibrational dynamics of the CD3zeta membrane peptide using heterodyned two-dimensional infrared photon echo spectroscopy

Heterodyned two-dimensional infrared (2D IR) spectroscopy has been used to study the amide I vibrational dynamics of a 27-residue peptide in lipid vesicles that encompasses the transmembrane domain of the T-cell receptor CD3zeta. Using 1-(13)C[Double Bond](18)O isotope labeling, the amide I mode of the 49-Leucine residue was spectroscopically isolated and the homogeneous and inhomogeneous linewidths of this mode were measured by fitting the 2D IR spectrum collected with a photon echo pulse sequence. The pure dephasing and inhomogeneous linewidths are 2 and 32 cm(-1), respectively. The population relaxation time of the amide I band was measured with a transient grating, and it contributes 9 cm(-1) to the linewidth. Comparison of the 49-Leucine amide I mode and the amide I band of the entire CD3zeta peptide reveals that the vibrational dynamics are not uniform along the length of the peptide. Possible origins for the large amount of inhomogeneity present at the 49-Leucine site are discussed.     

焙烧硼钠钙石在高固液比氯化铵溶液中的溶解动力学

Boron is available in the form of metal borates, especially of sodium and calcium, in nature[1]. The production of boron compounds has substantially increased recently due to increasing uses of these compounds in nuclear technology, in rocket engines as f…     

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Closed-Range Composition Operators on Weighted Bergman Spaces

For analytic self-maps φ of the unit disk, we show that recently given conditions that are both necessary and sufficient for the composition operator C _φ to be closed-range on the classical Bergman space \mathbbA²{\mathbb{A}^2} are actually necessary and sufficient in the general setting of the weighted Bergman spaces \mathbbA^p_a{\mathbb{A}^p_{\alpha}} , for 1 ≤ p < ∞ and weights of the form (1 - |z|²)^a{(1 - |z|^2)^{\alpha}} ; where α > −1. Along the way, we show how work done in a paper of J. Akeroyd, P. Ghatage and M. Tjani can be used to improve upon the most definitive of these conditions, and we give applications.     

An improved synthesis of 3,5-disubstituted isoxazoles and pyrazoles from C(α),O-dilithiooximes and C(α),N-dilithiophenylhydrazones

C(α),O-Dilithiooximes and C(α),N-dilithiophenylhydrazones were prepared using an excess of lithium diisopropylamide (1:3). Condensation with esters followed by acid cyclization gave isoxazoles and pyrazoles.     

Cyclopentyl derivatives of 8-azahypoxanthine and 8-azaadenine. Carbocyclic analogs of 8-azainosine and 8-azaadenosine

Four types of carboeyclic analogs of 8-azahypoxanthine and 8-azaadenine nucleosides have been prepared. This group of analogs is comprised of derivatives having the (±)-as-3-(hydroxy-methyl)cyclopentyl,(±)-trans-3-hydroxy-cis-4-(hydroxymethyl)cyclopentyl), (±)-trans-2-hydroxy-cis-4-(hydroxymethyl)cyclopentyl, and (±)-trans-2, trans-3-dihydroxy-cis-4-(hydroxymethyl)-cyelopentyl groups at position 3 of 3,6-dihydro-7H-v-triazolo[4,5-d]pyrimidm-7-one and of 7-amino-3H-v-triazolo[4,5-d]pyrimidine. Diazotization of (5-amino-6-chloropyrimidin-4-yl-amino)eyclopentane derivatives and acidic hydrolysis, without isolation of the resulting 7-chloro-3H-v-triazolo[4,5-d]pyrimidines yielded the 8-azahypoxanthine derivatives (III). Treatment of unpurified 7-chloro-3H-v-triazolo[4,5-d]pyrimidines with anhydrous ammonia gave the 8-azaadenine derivatives (IV). The cyclopentane analogs of 8-azaadenylic acid and of 8-aza-adenosine 3′,5′ -cyclic monophosphate were prepared from the 8-azaadenosine analog.     

Elastic and inelastic scattering of 88 MeV 6Li ions

The elastic scattering of 88 MeV ⁶Li ions has been studied for eleven targets ranging in mass from ²⁴Mg to ²⁰⁸Pb. Angular distributions were measured from about 10° c.m. in steps of 0.5°, mostly out to 60 or 70° c.m. where the elastic cross sections range from 10^?3 to 10^?5 of the Rutherford values. Inelastic data for exciting the lowest 2⁺ states of ^24,26Mg and ⁶⁰Ni were also obtained. The elastic data were analyzed using the optical model, with potentials of both Woods-Saxon and double-folding forms. The analysis confirms that the potentials for ⁶Li obtained from the folding model with the M3Y interaction need renormalizing by about 0.6, in agreement with results obtained at other energies. The inelastic data were compared to distorted-wave calculations. Coupled-channels analyses were also made for ^{24, 26}Mg, ⁶⁰Ni and ⁵⁹Co. Reorientation effects were found to be important to give the correct 2⁺ angular distributions for ^{24, 26}Mg and could also account for the differences between the elastic scattering from the odd-A and adjacent even-A targets.