Interfacial behavior of tetrapyridylporphyrin monolayer arrays

The behavior of monolayer films of free base 5,10,15,20-tetrapyridylporphinato (TPyP) and 5,10,15,20-tetrapyridylporphinato zinc(II) (ZnTPyP) on pure water, 0.1 M CdCl2, and 0.1 M CuCl2 subphases was investigated by surface pressure-area isotherms, specular X-ray reflectometry, and polarized total reflection X-ray absorption spectroscopy (PTRXAS). Surface pressure-area isotherms showed significant differences in the area per molecule on pure water compared to that on salt subphases, with a marked increase in the area observed on the salt solutions. This behavior was noted for both forms of the porphyrin and both salts investigated. Modeling of specular X-ray reflectometry data indicated that thinner and more electron dense layers on salt subphases best fit the observed profiles. These data suggest that the porphyrin macrocycle is oriented parallel to the interface on salt subphases and takes on a tilted conformation on pure water. In the case of ZnTPyP, PTRXAS was used to determine the orientation of the porphyrin moiety relative to the surface and to probe the coordination of the central Zn ion. In agreement with the pressure-area isotherms and reflectometry, the PTRXAS data indicate a change in orientation on the salt subphases.     

Comparison of the compact dry EC with the most probable number method (AOAC official method 966.24) for enumeration of Escherichia coli and coliform bacteria in raw meats. Performance-Tested Method 110402

Compact Dry E. coli/Coliform Count (EC) is a ready-to-use test method for the enumeration of Escherichia coli and coliform bacteria in food. The plates are presterilized and contain culture medium and a cold water-soluble gelling agent. The medium should be rehydrated with 1 mL diluted sample inoculated onto the center of the self-diffusible medium, allowing the solution to diffuse by capillary action. The plate can be incubated at 35 degrees C for 20-24 h and the colonies counted without any further working steps. The Compact Dry EC medium plates were validated as an analysis tool for determining colony-forming units (CFU) of E. coli and coliform bacteria from a variety of raw meats using 5 different types of raw meats. The performance tests were conducted at 35 degrees C. In all studies performed, no apparent differences were observed between the Compact Dry EC method and the AOAC Official Method 966.24 results. For the accuracy claim (n = 75), a correlation factor of r2 = 0.93 (E. coli) and r2 = 0.93 (coliform bacteria) could be assigned, as stated in the application for "Performance-Tested Method."     

Comparison of the compact dry YM with the FDA BAM method for enumeration of yeasts and molds in fruit-based products. Performance-Tested Method 100401

Compact Dry YM is a ready-to-use test method for the enumeration of yeasts and molds in fruit-based products. The plates are presterilized and contain nonwoven incorporated nutrients supplemented with antibiotics and a chromogenic enzyme substrate, 5-bromo-4-chloro-3-indoxyl phosphate, p-toluidine salt (X-phos), to facilitate counting dyes, and a cold water-soluble gelling agent. The medium should be rehydrated with 1 mL of diluted sample inoculated onto the center of the self-diffusible medium, allowing the solution to diffuse immediately by capillary action. The plate can be incubated at 25 degrees C for 7 days. The Compact Dry YM medium plates were validated as an analysis tool determining colony forming units of yeasts and molds from a variety of fruit-based products using 5 different fruit products. The performance tests were conducted at 25 degrees C. In all studies performed, no apparent differences were observed between the Compact Dry YM method and the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA BAM) method results (P > 0.05). For the accuracy claim (n = 75), a correlation factor of r2 = 0.99 could be assigned, as stated in the application for Performance-Tested Method.     

Effects of intermolecular vibrational coupling and liquid dynamics on the polarized Raman and two-dimensional infrared spectral profiles of liquid N,N-dimethylformamide analyzed with a time-domain computational method

A time-domain method for calculating polarized Raman and two-dimensional infrared (2D-IR) spectra that includes the effects of both the diagonal frequency modulations (of individual molecules in the system) and the off-diagonal (intermolecular) vibrational coupling is presented and applied to the case of the amide I band of liquid N,N-dimethylformamide. It is shown that the effect of the resonant off-diagonal vibrational coupling and the resulting delocalization of vibrational modes is clearly seen as the noncoincidence effect in the polarized Raman spectrum and some spectral features (especially as asymmetric intensity patterns) in the 2D-IR spectra. The type of 2D-IR spectra (concerning the polarization condition) most appropriate for observing this effect is discussed. On the basis of the agreement between the observed and calculated band profiles of the polarized Raman spectrum, the time dependence of the transient IR absorption anisotropy is also calculated. The method of evaluating the extent of delocalization of vibrational modes that is relevant to the features of these optical signals in the time and frequency domains is discussed. The nature of the molecular motions (concerning the liquid dynamics) that are effective on the diagonal frequency modulations is also examined.     

Development of dual gradient column in liquid chromatography

The dual gradient column, in which both the chemical property of the stationary phase and the flow velocity in the mobile phase are heterogeneous longitudinally along the column, is developed to obtain the mobile phase gradient-like elution in an isocratic condition. Here, the step-wise dual gradient columns were prepared by connecting an inlet column (I.D. 50 microm, packed with ODS) serially to an outlet column (I.D. 100-200 microm, packed with the mixture of ODS and C1 [9:1]). The retention behavior of alkylbenzenes was able to be controlled in the dual gradient column depending on the variation in the flow velocity. Moreover, the change in retention behavior induced by the flow velocity variation for the dual gradient columns was quite different from that by the variation in organic modifier content of the mobile phase in isocratic elution for a single gradient column and can induce the similar effect with an ordinary gradient elution in a mobile phase composition.     

Bioluminescence color modulation of Vibrio fischeri strain Y1 coupled with alterable levels of endogenous yellow fluorescent protein and its fluorescence imaging

Bioluminescence (BL) (lambda(max) approximately 535 nm) of Vibrio fischeri strain Y1 has been previously characterized in terms of the fluctuation in intracellular levels of yellow fluorescent protein (YFP). In this study fluorescence microscopic analysis has revealed that yellow fluorescence, as well as blue fluorescence attributable to a luciferase intermediate, is localized to the periphery of V. fischeri Y1 cells. This finding indicates that both YFP and the luciferase are present in the vicinity of the cell membrane. By using cyanide to enhance yellow BL, it has been shown that BL modulation is coupled with the fluctuations in the intracellular levels of YFP and the primary emitter. On the basis of the BL characterization, combined with results of a sedimentation experiment, it has been shown that larger cells produce a relatively stronger yellow BL. Two-dimensional gel electrophoresis of cell-protein extracts has shown that the YFP level is more alterable than the luciferase level. It is postulated that the yellow BL modulation takes place in connection with cell growth.     

Catalytic removal of N-allyloxycarbonyl groups using the [CpRu(IV)(pi-C3H5)(2-quinolinecarboxylato)]PF6 complex. A new efficient deprotecting method in peptide synthesis

A variety of amines including even sterically less demanding and highly nucleophilic secondary amines have been efficiently deprotected without decarboxylative N-allylation from the corresponding N-allyloxycarbonyl (N-AOC) compounds by using a catalytic amount of [CpRu(IV)(pi-C3H5)(2-quinolinecarboxylato)]PF6 in the presence of 1 molar amount of trifluoromethanesulfonic acid, the general utility of which has been demonstrated by the efficient synthesis of a collagen protein unit tripeptide, Pro-Pro-Gly.     

Preparation, characterization and properties of novel covalently surface-functionalized zinc oxide nanoparticles

Novel covalently surface-modified zinc oxide (ZnO) nanoparticles (NP) (ZHIE) were successfully prepared, which have organic chains composed of hydrophilic amide and urethane linkages, and terminal amino groups on the surfaces, using zinc acetate monohydrate. FTIR spectroscopy, X-ray analysis and TEM observation suggested that the resultant ZHIE NPs have the mean sizes of about 10 nm in diameters, the organic chains linking the amino groups in the terminals and wurtzite crystal structure. UV-vis absorption spectrum of the ZHIE NPs in methanol showed maximum absorption band at 348 nm, supporting the TEM observations. Photoluminescent spectrum measurements depicted that the ZHIE NPs show broad visible emission band on the basis of trapped-electron emission. Cytotoxicity and phagocytosis assays suggested that the ZHIE NPs are noncytotoxic, and the ZHIE-labeled zymosan particles derived by conjugation of the ZHIE NPs with zymosan are internalized into the cells and generate fluorescence based on the ZHIE NPs.     

Rotational dynamics of solvated carbon dioxide studied by infrared, Raman, and time-resolved infrared spectroscopies and a molecular dynamics simulation

Rotational dynamics of solvated carbon dioxide (CO(2)) has been studied. The infrared absorption band of the antisymmetric stretch mode in acetonitrile is found to show a non-Lorentzian band shape, suggesting a non-exponential decay of the vibrational and/or rotational correlation functions. A combined method of a molecular dynamics (MD) simulation and a quantum chemical calculation well reproduces the observed band shape. The analysis suggests that the band broadening is almost purely rotational, while the contribution from the vibrational dephasing is negligibly small. The non-exponential rotational correlation decay can be explained by a simple rotor model simulation, which can treat large angle rotations of a relatively small molecule. A polarized Raman study of the symmetric stretch mode in acetonitrile gives a rotational bandwidth consistent with that obtained from the infrared analysis. A sub-picosecond time-resolved infrared absorption anisotropy measurement of the antisymmetric stretch mode in ethanol also gives a decay rate that is consistent with the observed rotational bandwidths.     

1,2-Dimethoxy-4,5-dimethylene: a new protecting group for acyclic amino acid derivatives prepared by Stevens rearrangement

A new protecting group, 1,2-dimethoxy-4,5-dimethylene, for acyclic amino acid derivatives could be introduced by N,N-dialkylation with 1,2-bis(bromomethyl)-4,5-dimethoxybenzene (1) and removed via amine de-alkylation with acyl chlorides. The method can be used with base-induced [2,3] and [1,2] Stevens rearrangement products.