A method to circumvent the lot number of activated carbon affecting the performance of activated carbon silica gel columns used for cleanup of blood samples for analysis of 29 hazardous organochlorine compounds

We have previously described the use of a tandem simplified multilayer silica gel-activated carbon dispersed silica gel (TS-ML-AC) column for the cleanup of blood samples for the analysis of 29 hazardous organochlorine compounds (OCs)--the 17 major polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/DFs) and 4 non-ortho- and 8 mono-ortho-polychlorinated biphenyls (PCBs). We noted that the performance of the activated carbon-silica gel (ACS) column (lower column) varied with the lot number of the ACS. In this study, we compared the elution profiles of OCs eluted on 5 ACS columns, each with a different ACS lot number, and found that only mono-ortho-PCBs #114 and #123 were affected by lot number. The problem was that the 50 ml of n-hexane required to elute all the OCs from the simplified multilayer silica gel (MLS) column (upper column) into the AC column (lower column) also eluted varying amounts of PCBs #114 and #123 from the ACS column by ACS lot number. Although we could prevent PCBs #114 and #123 from being eluted from the ACS column by reducing the n-hexane volume to 10 ml, this volume was not sufficient to elute all the OCs from the MLS column. We solved this by separating the two columns; the sample solution was eluted with 50 ml of n-hexane from the MLS column, this eluate was concentrated to about 0.3 ml using a rotary evaporator, and then the concentrated solution was cleaned up on the ACS column. The recovery rates of #114 and #123 from blood samples were above 70% and the relative standard deviations of their concentration were below 10%, irrespective of the lot number, compared with recovery rates of 45-79% for #114 and 59-89% for #123, and relative standard deviations of their concentration above 15% when 50 ml of n-hexane was run through the tandem column. Our modified method affords reliable and reproducible cleanup of blood samples for analysis of 29 OCs, irrespective of the ACS lot number.     

Synthesis of phenyl arsenic analytical standards related to contaminated well water in Kamisu,Ibaraki, Japan

To facilitate, by the provision of internal standards, the liquid chromatographic and mass spectrometric analysis of diphenylarsinic acid in well water and other samples related to an incident of environmental contamination in Kamisu, Ibaraki, Japan, syntheses of the analogous perdeuterated and mono‐meta‐ and di‐meta‐methylated acids were undertaken. The acids were synthesized by cleavage of the triarylarsines by sodium in liquid ammonia. The triarylarsines were made from the reaction of arsenous chloride and sodium with the appropriate aryl‐bromo compound. Properties of the compounds are given. Copyright © 2005 John Wiley & Sons, Ltd.     

Orthogonal nonnegative matrix tri-factorization based on Tweedie distributions

Advances in Data Analysis and Classification - Orthogonal nonnegative matrix tri-factorization (ONMTF) is a biclustering method using a given nonnegative data matrix and has been applied to...     

Interactions between crossed hair fibers at the nanoscale

The atomic force microscope fiber probe is used to directly measure the forces and friction between two human hairs under various conditions. It is shown that the forces between the hair fibers in solution can be well explained by a DLVO interaction and that cationic surfactant modifies the interactions in a manner entirely consistent with current views of adsorption behavior. A Coulombic attraction occurs between the crossed hair fibers in air due to the heterogeneity of the surface, and at shorter separations a clear dispersion interaction is observed. Exposure of the hair to a bleaching solution leads to the removal of the adhesion and solely a double-layer interaction. Two crossed hair fibers obey Amontons' classic law of friction, with a linear relation between applied load and frictional force, allowing the determination of a friction coefficient; positively charged surfactant adsorption is shown to reduce the friction coefficient between the fibers in a manner consistent with boundary lubrication by a palisade layer.     

Self‐Assembly of One‐ and Two‐Dimensional Hemoprotein Systems by Polymerization through Heme–Heme Pocket Interactions

Supramolecular protein polymers : When a heme moiety was introduced to the surface of an apo‐cytochrome b₅₆₂(H63C) mutant, supramolecular polymers formed through noncovalent heme–heme pocket interactions. The incorporation of a heme triad as a pivot molecule in the protein polymer further led to a two‐dimensional protein network structure, which was visualized by tapping‐mode atomic force microscopy (see picture).

     

7,11-epi-thyrsiferol: completion of its synthesis, evaluation of its antimitotic properties, and the further development of an SAR model

We (a) describe the completion of a total synthesis of 7,11-epi-thyrsiferol (4), (b) compare the antimitotic activities of thyrsiferol (2), Delta15,28-dehydrothyrsiferol (3), and 7,11-epi-thyrsiferol (4), (c) evaluate the synergistic behavior of the title compound and colchicine to inhibit cell proliferation, and (d) describe the results of conformational searches that provide additional insight concerning the SAR profile of the thyrsiferol family of natural products.     

Adsorption and phase transition of alkanol and fluoroalkanol at electrified mercury/aqueous solution interface

The adsorption behavior and the phase transition of alkanol and fluoroalkanol at the electrified mercury/aqueous solution interface were investigated by the interfacial tension measurements and the thermodynamic analysis. In the alkanol system, it is found that the phase transitions in low interfacial densities occur: the ones from the zero adsorption to the gaseous or the expanded state and the gaseous to the expanded state at the electrified interface depending on the electrostatic nature as well as the concentration in the bulk phase. These phase transitions were verified by the thermodynamic equations derived by the assumption of coexistence of two phases at the electrified interface. Furthermore the distribution of ionic species in the interfacial region is discussed on the basis of dependence of the interfacial charge density of solution phase on an applied potential. Fluoroalkanol, on the other hand, was practically not adsorbed at the electrified interface within this experimental condition. The zero adsorption of fluoroalkanol molecules suggests the driving force of the adsorption may be the interaction hydrophobic group of alcohol molecule and mercury.     

Competitive photoinduced electron transfer by the complex formation of porphyrin with cyclodextrin bearing viologen

Photoinduced electron transfer between a porphyrin and a new guest cyclodextrin bearing viologen occurs by a supramolecular formation with conformational change of a guest molecule.     

Microscopic observation and in-situ Raman scattering studies on high-pressure phase transformations of Kr hydrate

Direct observations through a microscope and in-situ Raman scattering measurements of synthesized single-crystalline Kr hydrate have been performed at pressures up to 5.2 GPa and 296 K. We have observed that the initial cubic structure II (sII) of Kr hydrate successively transforms to a cubic structure I (sI), a hexagonal structure, and an orthorhombic structure (sO) called "filled ice" at 0.45, 0.75, and 1.8 GPa, respectively. The sO phase exists at least up to 5.2 GPa. In addition to these transformations, we have also found the new phase behavior at 1.0 GPa, which is most likely caused by the change of cage occupancy of host water cages by guest Kr atoms without structural change. Raman scattering measurements for observed phases have shown that the lattice vibrational peak at around 130 cm(-1) disappears in the pressure region of sI, which enables us to distinguish the sI phase from sII and sH phases.