Moment analysis of retention equilibrium, mass transfer kinetics, and thermodynamic properties in reversed-phase liquid chromatography using phenyl bonded silica gel

Information about retention equilibrium, mass transfer kinetics, and related thermodynamic properties of chromatography using phenyldimethylsilyl (Ph)-silica gel was derived by moment analysis of pulse response peak profiles. The results for the Ph-silica gel were compared with those for octadecyldimethylsilyl (C18)-silica gel. Some parameters characterizing the chromatographic behavior of the two stationary phases were correlated with the hydrophobic surface area of sample molecules. Surface diffusion had a predominant role for intraparticle diffusion. An enthalpy-entropy compensation was established for both the retention equilibrium and surface diffusion. A linear correlation was observed between the logarithm of surface diffusion coefficient (Ds) and that of retention equilibrium constant (Ka), suggesting the establishment of a linear free energy relationship. The ratio of Ds to molecular diffusivity (Dm) decreased with increasing Ka and was correlated by a single curved line. The value of Ds was of the same order of magnitude with Dm when Ka became negligible. These results suggest the presence of a sort of correlation between surface diffusion and molecular diffusion and the restriction of the molecular mobility by surface diffusion due to the retention strength.     

Influence of the column radial heterogeneity on the determination of single-component isotherms by the elution by characteristic point method

The influence of the column radial heterogeneity on the determination of equilibrium isotherm data by the elution by characteristic point (ECP) method is studied using nondimensional numerical calculations and taking into account typical radial distributions of the mobile phase flow velocity and the column efficiency across a column. Overloaded elution peaks were calculated with the equilibrium-dispersive model as a function of four dimensionless parameters, the number of theoretical plates at the center of the column, the Langmuir equilibrium constant, the retention and the loading factors. The influence of the mass transfer resistances and the radial heterogeneity of the column on the ECP data was analyzed by comparing the true isotherm and the one estimated from the diffuse profile of overloaded peaks. The results provide information on the accuracy of the ECP method. The error made increases with increasing degree of radial heterogeneity. This error can be corrected by using the results of the nondimensional numerical calculations, allowing a further extension of the applicability of the ECP method.     

Continuous-wave all-solid-state 244 nm deep-ultraviolet laser source by fourth-harmonic generation of an optically pumped semiconductor laser using CsLiB6O10 in an external resonator

We report an all-solid-state laser system that generates over 200 mW cw at 244 nm. An optically pumped semiconductor laser is internally frequency doubled to 488 nm. The 488 nm output is coupled to an external resonator, where it is converted to 244 nm using a CsLiB(6)O(10) (CLBO) crystal. The output power is limited by the available power at 488 nm, and no noticeable degradation in output power was observed over a period of several hours.     

Truth‐table Schnorr randomness and truth‐table reducible randomness

Schnorr randomness and computable randomness are natural concepts of random sequences. However van Lambalgen’s Theorem fails for both randomnesses. In this paper we define truth‐table Schnorr randomness (defined in 6 too only by martingales) and truth‐table reducible randomness, for which we prove that van Lambalgen's Theorem holds. We also show that the classes of truth‐table Schnorr random reals relative to a high set contain reals Turing equivalent to the high set. It follows that each high Schnorr random real is half of a real for which van Lambalgen's Theorem fails. Moreover we establish the coincidence between triviality and lowness notions for truth‐table Schnorr randomness. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Derandomization in game-theoretic probability

We give a general method for constructing a deterministic strategy of Reality from a randomized strategy in game-theoretic probability. The construction can be seen as derandomization in game-theoretic probability.     

Zeeman effect of atomic uranium in the high lying odd levels measured by laser induced fluorescence spectroscopy

We measured Zeeman effect of atomic uranium spectra using laser induced fluorescence spectroscopy, and derived the J-value and g-factor of the second step levels. J-values and g-factors of high lying odd levels could be obtained. These data, especially the g-factors, have almost been unknown so far. We could verify our method which can be useful to measure J-values and g-factors of high lying levels of complex atoms like uranium. Received 27 July 1999 and Received in final form 30 November 1999     

QSNPlite, a software system for quantitative analysis of SNPs based on capillary array SSCP analysis

We present a newly developed software called "QSNPlite" that comprehensively interprets the data of SSCP and sequencing analyses obtained from capillary array electrophoresis systems used in the quantitative characterization of SNPs. QSNPlite assists in the genotyping of individuals with SNPs and in estimating the allele frequencies of SNPs using pooled DNA. We show that this estimation is accurate (mean absolute error, 1.4%) by comparing the results of the pooled analysis using QSNPlite with the true frequencies based on the allele counting after performing individual genotypings. The QSNPlite program runs on Windows XP and can be used to determine the allele frequencies of SNPs among a large number of individuals, such as in association studies of disease-responsible genes using the candidate gene approach.     

Measurement of radiative lifetime and branching ratio of Gd I using three-step resonance ionization spectroscopy

Radiative lifetimes and branching ratios of atomic Gd were investigated by a three-step delayed photoionization method; the lifetimes of 10 even states in the 16000–18500 cm^?1 region and 64 odd states in the 31000–36500 cm^?1 region, and the branching ratios of 19 transitions originating from the f⁷ds^{2 9}D _J=2?6 ⁰ groundstate multiplets were measured for the first time. By combining these experimental lifetimes and branching ratios, oscillator strengths were determined and compared with previously reported values.     

Asymmetric synthesis of alpha-amino acids based on carbon radical addition to glyoxylic oxime ether

The first asymmetric synthesis of alpha-amino acids based on diastereoselective carbon radical addition to glyoxylic imine derivatives is reported. The addition of an isopropyl radical, generated from i-PrI, Bu(3)SnH, and Et(3)B in CH(2)Cl(2) at 25 degrees C, to achiral glyoxylic oxime ether 1 proceeded regioselectively at the imino carbon atom of the oxime ether group to give an excellent yield of the C-isopropylated product 2. The competitive reaction using glyoxylic oxime ether 1 and aldoxime ether 4 showed that the reactivity of the glyoxylic oxime ether toward nucleophilic carbon radicals was enhanced by the presence of a neighboring electron-withdrawing substituent. Thus, the alkyl radical addition to glyoxylic oxime ether 1 proceeded smoothly even at -78 degrees C, in contrast to the unactivated aldoxime ether 4. A high degree of stereocontrol in the carbon radical addition to the glyoxylic oxime ether was achieved by using Oppolzer's camphorsultam as a chiral auxiliary. The stannyl radical-mediated reaction of the camphorsultam derivative 6 with an isopropyl radical at -78 degrees C afforded a 96:4 diastereomeric mixture, 7a, of the C-isopropylated product. The reductive removal of the benzyloxy group of the major diastereomer (R)-7a, by treatment with Mo(CO)(6) and the subsequent removal of the sultam auxiliary by standard hydrolysis, afforded the enantiomerically pure D-valine (R)-12 without any loss of stereochemical purity. To evaluate the new methodology, a variety of alkyl radicals were employed in the addition reaction which gave the alkylated products 7 with excellent diastereoselectivity, allowing access to a wide range of enantiomerically pure natural and unnatural alpha-amino acids. Even in the absence of Bu(3)SnH, treatment of 6 with alkyl iodide and Et(3)B at 20 degrees C gave the C-alkylated products 7 with moderate diastereoselectivities. The use of Et(2)Zn as a radical initiator, instead of Et(3)B, was also effective for the radical reaction. The enantioselective isopropyl radical addition to 1 using (R)-(+)-2, 2'-isopropylidenebis(4-phenyl-2-oxazoline) and MgBr(2) gave excellent chemical yield of the valine derivative 2 in 52% ee.     

A single-strand conformation polymorphism method for the large-scale analysis of mutations/polymorphisms using capillary array electrophoresis

We present a high-throughput single-strand conformation polymorphism (SSCP) method, performed on a commercially available capillary array DNA sequencer. We tested various sieving matrices and electrophoretic conditions, using 51 DNA fragments which included 45 fragments carrying only one single nucleotide polymorphism (SNP), 4 fragments having two SNPs and 2 fragments with insertion or deletion. Resolution of alleles was improved by increasing concentrations of both sieving matrices and buffers, and all examined polymorphisms of DNA fragments were detected, most of them (45 fragments) as clearly split allele peaks in heterozygotes. Allele frequencies of SNPs can be estimated accurately by determining the relative amounts of alleles in pooled DNA. In this method, the turn-around time for the analysis of 96 samples is less than 3 h. These results demonstrate that capillary array-based SSCP is an efficient and accurate technique for the large-scale quantitative analysis of mutations/polymorphisms.