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951.
952.
We report the results of studies of various aspects of the counter diabatic field paradigm, a recipe that generates adiabatic population transfer between levels by assisting a given field so that the total field generates the population transfer that the adiabatic approximation suggests for the given field. The sensitivity of this recipe to the pulse parameters and to Gaussian stochastic phase fluctuations between the fields has been investigated. Ladder-climbing population transfer between the vibrational levels of a nonrotating Morse oscillator is examined, and a numerical demonstration of the efficiency of the scheme is given. 相似文献
953.
4-Oxoazetidin-2-ylphosphonates and phosphinates, obtained from Arbusov reactions of 4-acetoxyazetidin-2-one and 4α-acetoxy-3β-phthalimido-2-one with a variety of phosphites and phosphonites, were hyrdolysed to β-phosphono- and β-phosphino β-alanine (phosphono- and phosphinoaspartic acid) derivatives. In model studies for their incorporation in peptides, conditions for the selective removal of protecting groups for carboxylic acids, phosphonic and phosphinic acids, and amines, in derived di- and tri-peptides were investigated. Alanyl and alanyl alanyl peptide incorporation into bacteria was studied. 相似文献
954.
We report the results of digital video microscopy studies of the large particle displacements in a quasi-two-dimensional binary mixture of large (L) and small (S) colloid particles with diameter ratio sigma(L)/sigma(S)=4.65, as a function of the large and small colloid particle densities. As in the case of the one-component quasi-two-dimensional colloid system, the binary mixtures exhibit structural and dynamical heterogeneity. The distribution of large particle displacements over the time scale examined provides evidence for (at least) two different mechanisms of motion, one associated with particles in locally ordered regions and the other associated with particles in locally disordered regions. When rhoL*=Npisigma(L) (2)/4A< or =0.35, the addition of small colloid particles leads to a monotonic decrease in the large particle diffusion coefficient with increasing small particle volume fraction. When rhoL* > or =0.35 the addition of small colloid particles to a dense system of large colloid particles at first leads to an increase in the large particle diffusion coefficient, which is then followed by the expected decrease of the large particle diffusion coefficient with increasing small colloid particle volume fraction. The mode coupling theory of the ideal glass transition in three-dimensional systems makes a qualitative prediction that agrees with the initial increase in the large particle diffusion coefficient with increasing small particle density. Nevertheless, because the structural and dynamical heterogeneities of the quasi-two-dimensional colloid liquid occur within the field of equilibrium states, and the fluctuations generate locally ordered domains rather than just disordered regions of higher and lower density, it is suggested that mode coupling theory does not account for all classes of relevant fluctuations in a quasi-two-dimensional liquid. 相似文献
955.
Suya Wang James D. Stuart Huiqiong Ke Steven P. Levine 《Journal of separation science》1991,14(11):757-761
A 15 second, high speed, gas chromatographic determination has been performed on the volatile aromatic compounds in gasoline-contaminated ground water following manual, static headspace sampling. Retention time reproducibility of the seven peaks studied ranged from 0.25 to 0.67 per cent (average relative standard deviation). Excellent linear correlations were obtained for plots of either peak height or peak area against the concentration of the compounds. Comparison was made between the results obtained from the analysis of three replicate samples of gasoline-contaminated ground water by the high speed GC, by two field-portable GCs, and by a laboratorybased GC. It is worthy of note that all the high speed GC analyses required for this study were accomplished in one day. 相似文献
956.
Miller EL Bimbo AP Walters DE Barlow SM Sheridan B 《Journal of AOAC International》2002,85(6):1374-1381
A revised method to determine solubility of nitrogen in dilute pepsin, using 0.0002% pepsin in place of 0.2% in AOAC Official Method 971.09, was tested in 16 laboratories with 12 samples of fishmeal. Results were calculated according to 2 procedures: AOAC Official Method 971.09 and a method described in 1964 by researchers at the Torry Research Station (Aberdeen, Scotland), and generally referred to as the modified Torry method. Variations in the method of shaking and source of pepsin were also investigated. Pepsin solubility values were lower and more variable when calculated by the Torry procedure. The method of shaking apparently affected the result when calculated according to the Torry but not the AOAC method. The source of pepsin had no significant effect on between-laboratory variability, but a comparison of the 2 main sources within one laboratory resulted in highly significant differences. Based on this study, the International Fishmeal and Fish Oil Organization has adopted this new method, using 0.0002% pepsin but keeping the AOAC method of calculation. The type of shaker and source of pepsin are recommended but are not mandatory. The repeatability and reproducibility limits of this new method are 1.6 and 3.3% units of solubility, respectively. 相似文献
957.
Ruma?Karmakar Chirantan?Roy?Choudhury Andrei?S.?Batsanov Stuart?R.?Batten Samiran?MitraEmail author 《Structural chemistry》2005,16(5):535-539
Two new complexes [CuBr(C11H13N2O)] (1) and [Cu(NCO)(C11H13N2O)] (2) containing the tridentate Schiff base ligand, N-(1-acetyl-2-propylidene)(2-pyridylmethyl) amine which is the 1:1 condensation product of acetylacetone and 2-aminomethylpyridine, have been synthesised and characterised by elemental analysis, IR and electronic spectra, electrochemical study and single crystal X-ray diffraction study. Crystal structures reveal that the copper atom in both the complexes are in square geometry formed by the N2O donor set of the Schiff base and a bromine atom in 1 and one cyanate ligand in 2. Both bromide and isocyanate ligands act in a terminal monodentate fashion. 相似文献
958.
F. H. Müller H. A. Stuart H. Lange L. Horner G. Brauer J. Reitstötter H. Erbring H. Seifert J. Wolf 《Colloid and polymer science》1956,149(1):48-50
Ohne Zusammenfassung 相似文献
959.
A five-level four-pulse phase-sensitive extended stimulated Raman adiabatic passage scheme is proposed to realize complete control of the population transfer branching ratio between two degenerate target states. The control is achieved via a three-node null eigenstate that can be correlated with an arbitrary superposition of the target states. Our results suggest that complete suppression of the yield of one of two degenerate product states, and therefore absolute selectivity in photochemistry, is achievable and predictable, even without studying the properties of the unwanted product state beforehand. 相似文献
960.
Thermal behaviour of substituted monoazo dyes I-XVI, have been investigated by means of differential thermal analysis (DTA)
and thermogravimetry (TG). The thermal stabilities of these dyes have been determined using the DTA and TG curves and the
influence of the substituents and intramolecular hydrogen bonds on the DTA and TG curves of the dyes together with the melting
points were also examined.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献