A methode for preparing an aqueous colloidal dispersion of organic materials by using water-soluble polymers: Dispersion ofΒ-carotene by polyvinylpyrrolidone

Summary A new method was developed for preparing an aqueous colloidal dispersion ofΒ-carotene. This method consists of preparing a solid mixture ofΒ-carotene and polyvinylpyrrolidone (PVP) from their chloroform solution by evaporating the solvent and dissolving the mixture into water. From filtration experiment and electron microscopic observation it was found thatΒ-carotene in its aqueous dispersion exists as colloidal particles with a diameter of about 100 ?. Spectroscopic data evidenced thatΒ-carotene is molecularly dispersed in solid of PVP. It was considered that PVP acts as a solid solvent forΒ-carotene and, at the same time, a stabilizing agent for its aqueous dispersion. Instead of PVP, such a hydrophilic-oleophilic substance as methylcellulose, polyvinylmethylether or Aerosol OT could be also used as the dispersing agent. Other materials thanΒ-carotene could be dispersed by similar technique.

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Zusammenfassung Es wird eine neue Methode zur Pr?paration einer w?\rigen Kolloid-Dispersion vonΒ-Carotin beschrieben. Diese Methode besteht aus Herstellen einer festen Mischung ausΒ-Carotin und Polyvinylpyrrolidon (PVP) aus der Chloroforml?sung durch Verdampfen des L?sungsmittels und anschlie\ende L?sung der Mischung in Wasser. Aus Filtration und elektronenmikroskopischen Aufnahmen l?\t sich zeigen, da\ dasΒ-Carotin molekulardispers im festen PVP verteilt ist. Das PVP wirkt offensichtlich als festes L?sungsmittel fürΒ-Carotin und gleichzeitig als stabilisiertes Agens für die w?\rige Dispersion. Anstelle von PVP k?nnen auch derartige hydrophile-oleophile Substanzen wie Methylcellulose, Polyvinylmethyl?ther oder Aerosol OT verwendet werden. Es k?nnen auch andere Materialien alsΒ-Carotin auf gleiche Weise dispergiert werden.

     

Unusual C25 steroids produced by a sponge-derived Penicillium citrinum

[structure: see text] Structurally unique steroids, isocyclocitrinol A (1) and 22-acetylisocyclocitrinol A (2), were isolated from the extract of a saltwater culture of sponge-derived Penicilliun citrinum. The structures were established by analysis of 1D and 2D NMR data. The absolute structures were determined on the basis of X-ray structure analysis and application of modified Mosher's method. Furthermore, the structure of cyclocitrinol (3a) previously isolated from a terrestrial P. citrinum was revised as 3b. Compounds 1 and 2 showed weak antibacterial activity against Staphylococcus epidermidis and Enterococcus durans.     

Polyelectrolyte complex films derived from polyethyleneoxide-maleic acid copolymer and chitosan: preparation and characterization

Polyelectrolyte complex films were prepared with polyethyleneoxide-maleic acid copolymer and chitosan using a casting/solvent evaporation method. The films were examined in terms of their IR spectra, surface and cross-section morphologies, cytotoxicity, and swelling behavior at different pH levels. To assess the potential of these films as a biomedical device, the profiles of the release of model drug from the CS/PEOMA films were examined at pH 4.8. The surface morphology of the films was quite smooth and uniform, and the cross-sectional morphology was dense and homogeneous. The swelling behaviors of CS/PEOMA films were found to depend on the pH of the solution as well as on the CS/PEOMA composition. Drug release from different CS/PEOMA films at pH 4.8 was found to be dependent on film composition. The results showed the potential applicability of CS/PEOMA film as a drug delivery vehicle.     

Temperature control technology by heat capacity change upon lock and key binding

We propose an innovative temperature control technology wherein a heat capacity change upon lock and key binding is applied. A proof-of-principle calculation is performed using a three-dimensional integral equation theory of a statistical mechanics of fluid (Ornstein-Zernike theory coupled by HNC closure). Logical correctness of the temperature control technology is verified by this calculation. The performance of the heat pump is discussed. In addition, a more effective condition of the heat pump is also discussed to improve the performance.     

Interlayer Reaction of Polyamine/α-Zirconium Phosphate Intercalation Compounds with Some Aldehydes

Abstract

The intercalation compound between α-zirconium phosphate and N,N′-bis-(3-aminopropyl)-1, 3-propanediamine has two different modifications with respect to the conformation of the guest amine molecules: one is “bent form” and the other “straight form”. Reactivity of each phase with a series of aldehydes was examined. ¹³C CP/MAS NMR indicated that the tetraamine reacts stereoselectively with aldehydes to form cis-imine in the interlayer spacing. Depending on the molecular size of aldehyde, it is found that a significant difference can be recognized in the yields of the imine products for the two phases of intercalation compounds. It is also noted that residual water molecules in the interlayer spacing play an important role in the imine formation reaction.     

Quantitative analysis of thin-film conductivity by scanning microwave microscope

We propose a novel method for high-throughput quantitative analysis of thin-film conductivity σ by using a scanning microwave microscope (SμM). We demonstrated that composition spread thin films of Ti_1-xNb_xO₂ can be utilized as a standard reference in a wide σ range. The shift in Q-value measured by SμM along the composition-spread axis showed a single peak, which moved to the lower x side with film thickness. This behavior was confirmed by electrical field simulation using the finite element method.     

N-myristoylated proteins,key components in intracellular signal transduction systems enabling rapid and flexible cell responses

N-myristoylation, one of the co- or post-translational modifications of proteins, has so far been regarded as necessary for anchoring of proteins to membranes. Recently, we have revealed that N^α-myristoylation of several brain proteins unambiguously regulates certain protein–protein interactions that may affect signaling pathways in brain. Comparison of the amino acid sequences of myristoylated proteins including those in other organs suggests that this regulation is involved in signaling pathways not only in brain but also in other organs. Thus, it has been shown that myristoylated proteins in cells regulate the signal transduction between membranes and cytoplasmic fractions. An algorithm we have developed to identify myristoylated proteins in cells predicts the presence of hundreds of myristoylated proteins. Interestingly, a large portion of the myristoylated proteins thought to take part in signal transduction between membranes and cytoplasmic fractions are included in the predicted myristoylated proteins. If the proteins functionally regulated by myristoylation, a posttranslational protein modification, were understood as cross-talk points within the intracellular signal transduction system, known signaling pathways could thus be linked to each other, and a novel map of this intracellular network could be constructed. On the basis of our recent results, this review will highlight the multifunctional aspects of protein N-myristoylation in brain.