Sorption of galactose by zeolite Y

The sorption of galactose by Na-Y, K-Y and Ba-Y zeolites has been investigated by isopiestic equilibration at 25°C. The equilibrium galactose and water contents of the zeolites were determined for water activitiesa _w in the range 0.111 <a _w < 0.98. It was found that the maximum uptake of galactose U ₀ ^G (observed fora _W 0) was highest for Na-Y and least for Ba-Y. In contrast at high water activities the galactose uptake was highest for Ba-Y and least for Na-Y.     

The branching ratio for K−p → Λγ at rest

The reaction K^?p → Λγ, produced by K^? stopping in a liquid hydrogen target, has been studied using a NaI(Tl) gamma-ray spectrometer. The branching ratio is

$\text{K}{}^{\mathrm{?}}\text{p}\text{→Λγ}\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{anything}\text{=(2.8±0.8)×10}{}^{\mathrm{?3}}$

based on 1355 events assigned to this branch. This is in conflict with a previous experiment, but agrees with one of the two published calculations, when recent values for the coupling constants and scattering amplitudes are used.     

Synthesis and N-Methyl-D-aspartate (NMDA) Antagonist Properties of the Enantiomers of α-Amino-5-(phosphonomethyl)[1,1′-biphenyl]-3-propanoic Acid. Use of a New Chiral Glycine Derivative

The enantiomers of the title compound, 7a and ent- 7a , and of substituted analogues are synthesized. The absolute configuration of 7a is deduced from that of (tert-butyl 2-tert-butyl)-3-methyl-4-oxoimidazolidin-1-carboxylate ( 15 ) and from the trans-configuration of the intermediate 17a which in turn is assigned on the basis of ¹H-NMR nuclear Overhauser effect (NOE) measurements. Instead of 15 , the 2-isopropyl-substituted analogue 21 can also be employed. Its preparation from glycine, methylamine, isobutyraldehyde, and (Boc)₂O, and the resolution through the bis-O,O′-(4-toluyl)tartrate salt 20 are described. In two functional tests (rat neocortical slice and frog hemisected spinal cord preparation) the (S)-enantiomer 7a (SDZ EAB 515) is shown to be a very potent, selective competitive NMDA antagonist.     

Bayesian interpretation of counting data

The application of Bayesian inferential methodology is applied to the analysis of counting data. A formulation leading to data-specific probability density functions is developed. A tabulation of frequently used confidence levels is given for the most common experimental situation. Approximate methods based upon the normal distribution are discussed.     

A new approach to relativistic multi-configuration quantum mechanics in titanium

Multiply-ionized atoms in plasmas and astronomical systems are predominantly of intermediate atomic numbers with open electron shells. The spectra seen in laboratory plasmas and astrophysical plasmas are dominated by characteristic Kα1,2 photoemission lines. Modelling these transitions requires advanced relativistic frameworks to begin to formulate solutions. We present a new approach to relativistic multi-configuration determination of Kα1,2 diagram and satellite energies in titanium to a high level of convergence, allowing accurate fitting of satellite contributions and the first agreement with profile to negligible residuals. These developments also apply to exciting frontiers including temporal variation of fundamental constants, theoretical chemistry and laboratory astrophysics.     

Factors influencing the synthesis and the post-modification of PEGylated pentafluorophenyl acrylate containing copolymers

Copolymerization reactions involving oligoethylene glycol acrylate (OEGA) or diethylene glycol acrylate (DEGA) with pentafluorophenyl acrylate (PFPA) have been performed by reversible addition fragmentation transfer (RAFT) polymerization. The effect of the reaction conditions on the nucleophilic acyl substitution reactions of PFPA was studied using a model amine (furfuryl amine). The resulting PEG/PFP functional copolymers were then used as scaffolds to produce a library of polymers by reaction with a range of amines.     

Deoxygenation of Pyridones Via Their Tetrazolyl Ethers

A mild process for the conversion of pyridones to the corresponding pyridines by palladium catalyzed ammonium formate hydrogenolysis of their (1-phenyltetrazol-2-yl) ethers is described.     

Transforming NMR data despite missing points.

Some NMR experiments produce data with several of the initial points missing. The inverse discrete Fourier transform (IDFT) assumes these points are present so the data cannot be so transformed without artifact-ridden results. This problem is often particularly severe when projection imaging with free-induction decays (FIDs). This paper compares recent methods for obtaining a projection from incomplete data and elaborates on their strengths and limitations. One method is to write the transform that would take the desired projection to the truncated data set, and then solve the matrix equation by singular value decomposition. A second replaces the missing data with zeros, so that an IDFT produces a projection with unwanted artifacts. Then one solves the matrix equation that takes the desired projection to the artifact-ridden projection. A third uses the same artifact-ridden projection, but fits the region outside the bandwidth of the sample with as many sinusoidal functions as there are missing data. The coefficients of these functions are estimates of the missing data, and the projection is obtained by transforming the completed FID or subtracting the extrapolation of the fitted curve from the region containing the object. We show that when all three methods are applicable, they theoretically produce the same result. They differ by ease of implementation and possibly by computational errors. They give a result similar to that of the previous method that iteratively corrects the FID and projection after repeated IDFTs and DFTs. We find that one can obtain a projection despite missing a substantial number of data.     

Rhodium catalyzed,one-pot,three component redox-neutral process towards fused ring heterocycles

A three component, rhodium-catalyzed isomerisation/1,3-dipolar cycloaddition reaction is described for the synthesis of fused ring heterocycles as endo/exo isomers, with the formation of three new bonds and four stereocenters.