Packed capillary column supercritical fluid chromatography of fat-soluble vitamins using liquid crystal polysiloxane coated particles

Summary Liquid crystal polysiloxane stationary phases were prepared by coating two different polymers on deactivated porous silica particles (10 m diameter, 80 Å pores). Deactivation of the silica particles before coating was necessary to prepare highly efficient and inert stationary phases for supercritical fluid chromatography (SFC). Fat-soluble vitamins E, A, K₁, K₂, D₂, and D₃ were separated on these columns using neat supercritical CO₂ as mobile phase. The analyses were completed within 40 min at 70 °C. The results were compared to those obtained using a capillary column packed with less ordered liquid crystalm,m-cyanobiphenyl-substituted polysiloxane coated particles. Reduced shape selectivity was observed with this cyanobiphenyl phase. The response factors of vitamins A, E, K₁, K₂, D₂, and D₃ when using the flame ionization detector (FID) were determined to be very similar.     

Molecular cloning of clathrin assembly protein gene (rCALM) and its differential expression to AP180 in rat brain

Binding of clathrin assembly protein to clathrin triskelia induces their assembly into clathrin-coated vesicle (CCV) in neurons. The clathrin assembly protein gene (rCALM) was cloned from rat brain cDNA library. rCALM deduced 69 kD molecule has overall 73% amino acid homology compared with that of AP180 protein. The N-terminal domain, where amino acid sequences are very similar with AP180, harbours binding sites for clathrin and inositides, as well as possible phosphorylation sites, but the proline rich C-terminal domain is different from that of AP180. The mRNA expression of rCALM and AP180 by in situ hybridization histochemistry revealed that the rCALM mRNA was more intensely expressed than that of AP180, and the distribution patterns were different from each other. These results suggest that the rCALM mediates the assembly of clathrin in neural and supporting cells of brain, and regulates the clathrin coated-vesicle formation through phosphorylation and inositide metabolism.     

An ab initio study of some structural features and the rotational barriers in performic acid,formic acid and hydrogen peroxide

Calculations on performic acid at the 4-31G level, with and without bond functions with complete geometry optimization, and at the (9, 5) level, with and without polarization functions and rigid rotation, all give no sign of a well in the potential energy curve for rotation about the O/O bond axis in the region of 50° – 90° ; and all but the unaugmented 4-31G basis set find the cis-cis planar conformer to be the most stable form. Calculations at the (9,5) level with rigid rotation find the energies of the other planar conformers, relative to the cis-cis conformer, to be 0.94, 1.50 and 14.80 kcal mol^?1 for the trans-trans, cis-trans and trans-cis structures respectively. These energies and also that for the barrier separating the cis-cis and cis-trans conformers, 1–2 kcal mol^?1, are discussed in relation to corresponding data for formic acid, hydrogen peroxide and several planar four heavy-atom molecules. Dipole moment calculations using the same basis sets would seem to favor a skew conformation as the most stable for performic acid, but comparisons between calculated and experimental values for formic acid and for hydrogen peroxide cast doubt on the validity of such results.     

Suzuki-Miyaura coupling reaction of aryl chlorides using di(2,6-dimethylmorpholino)phenylphosphine as ligand

Suzuki-Miyaura coupling was achieved on a variety of aryl chlorides by using di(2,6-dimethylmorpholino)phenylphosphine (L1) as a bulky electron-rich monoaryl phosphine ligand. We report the couplings of various chlorobenzenes and heteroaryl chlorides.     

Low-valent chemistry of cobalt amide. Synthesis and structural characterization of cobalt(II) amido, aryloxide, and thiolate compounds

The binuclear cobalt(II) amide complex [(CoL2)2-(TMEDA)] (1) [L = N(Si(t)BuMe2)(2-C5H3N-6-Me); TMEDA = Me2NCH2CH2NMe2] has been synthesized by the reaction of anhydrous CoCl2 with 2 equiv of [Li(L)(TMEDA)]. X-ray crystallography revealed that complex 1 consists of two [CoL2] units linked by one TMEDA ligand molecule, which binds in an unusual N,N'-bridging mode. Protolysis of 1 with the bulky phenol Ar(Me)OH (Ar(Me) = 2,6-(t)Bu2-4-MeC6H2) and thiophenol ArSH (Ar = 2,4,6-(t)Bu3C6H2) gives the neutral monomeric cobalt(II) bis(aryloxide) [Co(OAr(Me))2(TMEDA)] (2) and dithiolate [Co(SAr)2(TMEDA)] (3), respectively. Complexes 1-3 have been characterized by mass spectrometry, microanalysis, magnetic moment, and melting-point measurements, in addition to X-ray crystallography.     

A redox-active ionic liquid manifesting charge-transfer interaction between a viologen and carbazole and its effect on the viscosity,ionic conductivity,and redox process of the viologen

Redox-active ionic liquids (RAILs) are gaining attention as a material that can create a wide range of functions. We herein propose a charge-transfer (CT) RAIL by mixing two RAILs, specifically a carbazole-based ionic liquid ([CzC₄ImC₁][TFSI]) as a donor and a viologen-based ionic liquid ([C₄VC₇][TFSI]₂) as an acceptor. We investigated the effect of CT interaction on the physicochemical properties of the CT ionic liquid (CT-IL) using the results of temperature-dependent measurements of UV-vis absorption, viscosity, and ionic conductivity as well as cyclic voltammograms. We employed the Walden analysis and the Grunberg–Nissan model to elucidate the effect of the CT interaction on the viscosity and ionic conductivity. The CT interaction reduces the viscosity by reducing the electrostatic attraction between the dicationic viologen and TFSI anion. It also reduces the ionic conductivity by the CT association of the dicationic viologen and carbazole. The electrochemically reversible responses of the viologens in [C₄VC₇][TFSI]₂ and CT-IL are consistent with the Nernstian and the interacting two-redox site models. Notably, the transport and electrochemical properties are modulated by CT interaction, leading to unique features that are not present in individual component ILs. The inclusion of CT interaction in RAILs thus provides a powerful means to expand the scope of functionalized ionic liquids.

A redox-active ionic liquid (RAIL) consisting of a carbazole and viologen shows charge transfer (CT) interaction. The physicochemical properties are modulated by the CT interaction by comparison with the individual RAILs.     

In situ tissue pathology from spatially encoded mass spectrometry classifiers visualized in real time through augmented reality

Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates in situ tissue pathology from point-sampled mass spectrometry data. Spatially encoded pathology classifications are displayed at the site of laser sampling as color-coded pixels in an augmented reality video feed of the surgical field of view. This is enabled by two-way communication between surgical navigation and mass spectrometry data analysis platforms through a custom-built interface. Performance of the system was evaluated using murine models of human cancers sampled in situ in the presence of body fluids with a technical pixel error of 1.0 ± 0.2 mm, suggesting a 84% or 92% (excluding one outlier) cancer type classification rate across different molecular models that distinguish cell-lines of each class of breast, brain, head and neck murine models. Further, through end-point immunohistochemical staining for DNA damage, cell death and neuronal viability, spatially encoded PIRL-MS sampling is shown to produce classifiable mass spectral data from living murine brain tissue, with levels of neuronal damage that are comparable to those induced by a surgical scalpel. This highlights the potential of spatially encoded PIRL-MS analysis for in vivo use during neurosurgical applications of cancer type determination or point-sampling in vivo tissue during tumor bed examination to assess cancer removal. The interface developed herein for the analysis and the display of spatially encoded PIRL-MS data can be adapted to other hand-held mass spectrometry analysis probes currently available.

Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates in situ tissue pathology from point-sampled mass spectrometry data.     

Isolation of rice allergenic cDNA clones from a rice cDNA library by immunoscreening with a polyclonal antibody specific to 16 kD rice allergenic protein

Clinical cases of type-1 hypersensitive reaction to rice (Oryza sativa) have been reported in western countries as well as in Japan. Among rice proteins, 14-16 kD globulin proteins encoded by multiple gene family have been identified as major rice allergens. In this study, a rice cDNA library was constructed using lambda UniZap vector and screened with a rat anti-16 kD globulin protein polyclonal antibody in order to isolate Korean rice allergenic cDNA clones. Five independent cDNA clones, termed RAK1-5, were obtained after second rounds of plaque assay and immunoblot analysis. These clones encoded 13-19 kD recombinant proteins upon IPTG induction, which were identified by the polyclonal antibody in immunoblot analysis. DNA sequencing analysis showed that RAK1-4 have 99% sequence homology with RA5b, and RAK5 is closely related with RA14c. This result indicated that RA5b gene is widely distributed in our cDNA library among other possible rice allergenic genes, and more study is needed to isolate heterogeneous or novel rice allergen genes.     

Coherence and correlation parameters for thed 3 Π u − (v=0,1,2,3;N=1) states of H2

We have applied the density matrix formalism and the distorted-wave approximation to calculate the Stokes parameters for thed ³ Π _u ^? (v=0,1,2,3;N=1) states of H₂ excited from the X¹ ∑ _g ⁺ (v=0,N=1) state by electron impact at the incident energies ranging from 15 to 40 eV. Our results show that these parameters are nearly independent of the vibrational quantum number of the excited states. However, the polarization of the radiation emitted by the target in the subsequent decay process increases with increasing incident energies.     

Benzannelated analogs of phenanthro[1,2-b]- and [2,1-b]thiophene: Synthesis and structural characterization by two-dimensional NMR and X-ray techniques

Syntheses of benzo[3,4]phenanthro[1,2-b]thiophene, benzo[3,4]phenanthro[2,1-b]thiophene and their 1-methyl analogs are reported as potential constituents of solvent refined coal liquids and for mutagenicity testing. The attempted synthesis of the 13-methyl analogs which gave the 11-methyl isomers is also described. Total assignments of the ¹H- and ¹³C-nmr spectra based on long range optimized heteronuclear protoncarbon two-dimensional chemical shift correlation are reported. Carbon assignments obtained for benzo[3,4]-phenanthro[1,2-b]thiophene using this approach were confirmed with a 125 MHz ¹³C–¹³C INADEQUATE spectrum. X-Ray crystal structures were determined for benzo[3,4]phenanthro[1,2-b]thiophene and 1-methyl-benzo[3,4]phenanthro[2,1-b]thiophene. Both molecules were helically distorted from planarity. Close intramolecular contacts between the bay region H1–H13 and ClMe-H13 of 2.03 and 2.28 Å, respectively, were responsible for the distortions. There were no close intermolecular contacts of <3.5Å. both molecules refined to an R value of <0.05.