Influences of Target Size and Contrast on Near Infrared Diffuse Optical Tomography – a Comparison Between Featured-data and Full Time-resolved Schemes

Our recent diffuse optical tomography experiments on human lower legs and forearms are presented using the time-resolved measuring system and image reconstruction algorithm based on the modified generalized pulse spectrum technique. It was shown that the spatial resolution and quantitativeness of the resultant images, was rather poor, and the interior blood vessels invisible in the absorption images. To clarify this issue, the influences of target contrast and size on the image reconstruction were investigated with simulated data. We have found that the quantitativeness of the reconstructed optical properties was prone to be spoiled by the small size ratio and high contrast of the interior targets to the background, and the incompleteness of information embedded in the featured data-types, evidently answers for the degradation of the image quality. It was shown in a further simulative investigation that the image quality could be substantially improved by making full use of the time-resolved data.     

Detection of arsenobetaine in human blood

Arsenobetaine was detected and quantified unambiguously in human plasma, serum and red blood cells by the combination of HPLC with ICP MS. Three different column conditions, i.e. two ionpair chromatographies for anionic (LC-1) and cationic (LC-2) compounds and gel-permeation chromatography (LC-3), were employed to confirm the assignment. Arsenobetaine was detected in every sample as a major component of the water-soluble arsenic compounds, with an increasing concentration in plasma < serum < blood cell fractions. It was the sole detectable arsenic compound in LC-1 and LC-2, while a broad peak corresponding to high-molecular-weight compounds was identified in addition to arsenobetaine in LC-3.     

Identification of arsenobetaine and a tetramethylarsonium salt in the clam Meretrix lusoria

Chemical forms of arsenic were examined in six tissues (gill, mid-gut gland, siphon, foot, mantle and adductor muscle) of the clam Meretrix lusoria. The gill was found to contain higher levels of arsenic than the other tissues. Regardless of the nature of the tissues, the presence of arsenobetaine was established by HPLC0ICP; it was a minor arsenic compound in gill but a major one in the other tissues. The major arsenic compound in gill, which was more cationic than arsenobetaine, was obtained in a relatively pure state by ion-exchange chromatography, gel filtration and HPLC. It was positive to the Dragendorff reagent and iodine vapor but negative to ninhydrin reagent. Its ¹HNMR spectrum exhibited only one signal at δ 1.7 (singlet) and its FAB mass spectrum gave a base peak at m/e 135 [(CH₃)₄As⁺] and two significant peaks at m/e 120 [(CH₃)₃As] and 106 [(CH₃)₂AsH]. These results suggested that the major arsenic compound in gill exists as a tetramethylarsonium salt (CH₃)₄As⁺ · X^?. The tetramethylarsonium salt was also found as a minor component in the tissues other than the gill.     

New approach to unravel the structure–property relationship of methylcellulose

In the present paper we suggest a new concept to overcome some of the so far unsolved problems of the structure–property relationship of methylcellulose, the most important nonionic cellulose ether industrially produced in large scale. Not only from the viewpoint of scientific understanding, but also from that of the peculiar and application-determining behavior, the aggregation in aqueous solution and phase separation on heating are the most important questions. As a part of the concept, we had prepared amphiphilic block co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides as structural models of typical sequences in methylcellulose chains. Now static and dynamic light scattering measurements and transmission electron microscopy (TEM) were carried out using solutions of the oligomers in water. Ellipsoidal particles with dimensions of about 50 nm for the semi-major axis and of circa 25 nm for the semi-minor one could be detected. These findings agree with the radii of gyration and the hydrodynamic radii, determined by static and dynamic light scattering. The data preliminary obtained demonstrate the strong aggregation tendency of block-like methylated cello-oligosaccharides.     

A light-controlled reversible DNA photoligation via carbazole-tethered 5-carboxyvinyluracil

We describe a light-controlled template-directed reversible DNA photoligation via carbazole-tethered 5-carboxyvinyluracil. Carbazole-tethered 5-carboxyvinyl-2'-deoxyuridine-containing oligodeoxynucleotide (ODN) can be ligated by irradiation at 366 nm in the presence of template ODN, and the ligated ODN can be split by irradiation at 366 nm in the absence of template ODN.     

Colloidal crystallization of colloidal silica modified with ferrocenyl group-contained polymers in organic solvents

Surface modification of colloidal silica with ferrocenyl-grafted polymer and colloidal crystallization of the particles in organic solvent were studied. Poly(methyl methacrylate-co-vinylferrocene)-grafted silica never formed colloidal crystals in polar solvent, such as acetone, acetonitrile, ethanol and N,N-dimethylformamide (DMF), while poly(methyl methacrylate-co-ferrocenyl acrylate)-grafted silica gave colloidal crystallization in DMF. The particles prepared by grafting of poly(N,N-dimethylacrylamide-co-vinylferrocene), with vinylferrocene (Vfc) mole fraction of 1/13 and 1/23, were observed to give the crystallization in ethanol and DMF over particle volume fraction of 0.058. Further, silica modified with copolymer of Vfc and N-vinyl-2-pyrrolidone, N-vinylcarbazole or N-isopropylacrylamide formed colloidal crystals in ethanol and DMF. Especially, poly(N-isopropylacrylamide-co-Vfc)-grafted silica, which was composed of the highest mole fraction of vinylferrocene, 1/3, afforded colloidal crystallization in ethanol over particle volume fraction of 0.053. Relatively high polar vinylferrocene copolymer grafting of silica resulted in colloidal polymerization in organic solvents.     

Synthesis of gamma-hydroxybutenolides applying crossed aldol condensation in the presence of a bulky lewis acid and their anti-tumor activity

An improved synthesis of gamma-hydroxybutenolides 1a-d was achieved via crossed aldol condensation between aldehydes 2a-d and the protected gamma-hydroxy-beta-methylbutenolides 3 or 4 using the bulky Lewis acid, aluminum tris(2,6-diphenylphenoxide) (ATPH). Using this same methodology, the gamma-hydroxybutenolides 17a-d having various heteroaromatic rings were synthesized and their anti-tumor activities were evaluated.     

Preparation of fritless capillary using avidin immobilized magnetic particles for electrochromatographic chiral separation

In capillary electrochromatography (CEC), magnetic particles (MPs) were packed in a fused silica capillary by using the magnetic field to be retained without frits. For a chiral CEC separation, avidin was immobilized onto the surface of the MPs (AVI-MPs) as a stationary phase by using the physical adsorption technique. The injected AVI-MPs into the capillary were stably captured with the magnet (surface magnetic flux density, 250 mT) under the separation voltage of 10 kV (190 V/cm). By employing the fritless AVI-MPs packed capillary, the chiral separation of ketoprofen was successfully attained with the packing length of only 5 cm. Effects of the modification condition of avidin, pH of background solution, and the packing length on the enantioseparation were also investigated. Under the optimal condition, furthermore, the repeatability for the retention time of ketoprofen was better than 1.5% in the relative standard deviation and the capillary-to-capillary reproducibility was also acceptable in the prepared fritless capillaries.