On premelting of theC-form of stearic acid

Some evidence is given for the presence of a solid phase just below the melting point of stearic acid. It is not certain whether the existence of this new phase is due to impurities or not.

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Zusammenfassung Einige Beweise zur Gegenwart einer Festphase knapp unterhalb des Schmelzpunktes der StearinsÄure werden gegeben. Es ist nicht geklÄrt ob das Vorhandensein dieser neuen Phase auf Verunreinigungen zurückzuführen ist oder nicht.

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Résumé On donne plusieurs preuves de la présence d'une phase solide juste au-dessous du point de fusion de l'acide stéarique. Il n'est pas certain que l'existence de cette phase nouvelle soit due à des impuretés ou non.

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I wish to express my sincere thanks to the following people: Dr. J. A. Morrison for kindly sending the sample and helpful discussion, Dr. D. Dolphin for making the LKB 8700 calorimeter available to me, Dr. L. G. Harrison for allowing the use of his facilities, and Mr. B. Greene, Mr. J. Edwards and Mr. B. Powell for their excellent technical assistances in modifying the apparatus. The financial support from the University of British Columbia is also acknowledged.     

Poly(diacetylene)-nanofibers can be fabricated through photo-irradiation using natural polysaccharide schizophyllan as a one-dimensional mold

Schizophyllan interacts with various 1,4-diphenylbutadiyne derivatives to induce their chirally-twisted packing. A series of referential experiments using other polysaccharides (amylose, pullulan, dextran, etc.) and a carbohydrate-appended detergent (dodecyl-beta-d-glucopyranoside) indicates that these 1,4-diphenylbutadiyne derivatives are accommodated within a tubular cavity constructed by a helical superstructure of schizophyllan. In these 1,4-diphenylbutadiyne derivatives, 1,4-bis(p-propionamidophenyl)butadiyne can be easily polymerized through UV-irradiation, in which schizophyllan acts as a one-dimensional mold to produce the corresponding poly(diacetylene)s with fibrous morphologies. Detailed investigations on this unique approach to prepare the nanofibers revealed that it includes two individual processes, that is, 1) UV-mediated polymerization of encapsulated 1,4-bis(p-propionamidophenyl)butadiyne to produce immature nanofibers and 2) their reorganization through hydrophobic interfiber interactions into ordered nanofibers. The other 1,4-diphenylbutadiyne derivatives could not be polymerized through UV-irradiation, indicating that the p-propionamido-functionalities play substantial roles for a suitable packing of the monomer for the polymerization. The other 1,4-diphenylbutadiyne derivatives, however, can be also polymerized through gamma-ray irradiation in the presence of schizophyllan to give the corresponding poly(diacetylene)-nanofibers, emphasizing the wide applicability of the schizophyllan-based strategy for polymerization of various 1,4-diphenylbutadiyne derivatives.     

Stable metallic behavior and antiferromagnetic ordering of Fe(III) d spins in (EDO-TTFVO)2.FeCl4

We report the crystal structure and physical properties of the 2:1 FeCl4- salt of a new donor molecule, EDO-TTFVO. Crystal structure analysis of this salt revealed that the donor molecules formed a beta' '-type two-dimensional conducting layer, and there is a short S...Cl contact between the donor molecules and the FeCl4- ions, which is expected to mediate a strong pi-d interaction. This salt showed a stable metallic conducting behavior down to 0.3 K and an antiferromagnetic ordering at TN approximately 3.0 K, indicating that this salt becomes a new antiferromagnetic molecular metal at ambient pressure. The appearance of the magnetic ordering is considered to originate from the strong pi-d interactions between the donor molecules and the FeCl4- ions because the field dependence of magnetoresistances was remarkably affected below the antiferromagnetic transition temperature.     

Determination of acetaldehyde by a chemiluminescence method

The determination of acetaldehyde was achieved by monitoring the chemiluminescence emission from the luminol-potassium hexacyanoferrate (III) reaction in the presence of xanthine oxidase. The linear range was three orders of magnitude, the detection limit (2σ) was 4 × 10^?7 M and the relative standard deviation (n = 5) was 10.6% for 4.3 × 10^?7 M. No interference was observed from seven organic and inorganic species at a 1000-fold excess relative to a concentration of 1 × 10^?5 M acetaldehyde.     

Synthesis of Urinary Metabolites of Retinoic Acid

Urinary metabolites 5-methyl-5-[2-(2,6,6-trimethyl -3-oxo-1-cyclohexen-1-yl)-vinyl]-2-tetrahydrofuranone (1) and 5-[2-(6-hydroxymethyl-2, 6-dimethyl-3-oxo-1- cyclohexen-1-yl)vinyl]-5-methyl-2-tetrahydrofuranone (2) of retinoic acid have been synthesized from 4-[2,2,6-trimethyl-3-(tetrahydro-2 H -pyran-2-yl)oxy-1-cyclohexen-1-yl]-3-buten-2-one (4) and methyl 2-(3,3-ethylenedioxy-1-butenyl)-1, 3-dimethyl-4-oxo-2-cyclohexene-1-carboxylate (5) .     

The conversion of methylenomycin A to natural botryodiplodin and their absolute configurations

Natural (?)-botryodiplodin($\text{1}$) has been synthesized from an antibiotic methylenomycin A ($\text{2}$). The absolute configurations of (?)-botryodiplodin($\text{1}$ and methylenomycin A ($\text{2}$) have also been established as shown in $\text{1}$ and $\text{2}$ respectively.     

Chemo-enzymatic synthesis of fluorinated 2-N-acetamidosugar nucleotides using UDP-GlcNAc pyrophosphorylase

Two non-natural fluorinated 2-N-acetamidosugar nucleotides, uridine 5'-diphosphate (UDP) 2-acetamido-2,4-dideoxy-4-fluoro-alpha-D-glucopyranose (UDP-4-FGlcNAc) 1 and its galacto isomer (UDP-4-FGalNAc) 2, were enzymatically constructed by treating chemically synthesized fluorinated 2-N-acetamidosugar 1-phosphates as the donor with UDP 2-acetamido-2-deoxy-alpha-D-glucopyranose pyrophosphorylase in the presence of uridine 5'-triphosphate (UTP).     

Evaluation of titanium dioxide as a pharmaceutical excipient for preformulation of a photo-labile drug: effect of physicochemical properties on the photostability of solid-state nisoldipine

To characterize the photocatalytic activity of TiO2 via solid-state reaction, the relationship between the physicochemical properties and photocatalytic activity of TiO2 was investigated and estimated from the results of photodegradation of nisoldipine. The photodegradation of nisoldipine was significantly enhanced by addition of TiO2. Two degradation products, nitroso-phenylpyridine derivative and nitro-phenylpyridine derivative, were formed. The degree of photocatalytic activity of TiO2 was quite different between the various types of TiO2 investigated, even when the crystalline phase was the same. As a result of the investigations into the relationship between the photocatalytic activity and physicochemical properties of TiO2, it was found that for the rutile form the photocatalytic activity has good correlation with specific surface area of TiO2, but poor correlation with water loss on drying of TiO2. However, for the anatase form, the photocatalytic activity has good correlation with water loss on drying of TiO2, but poor correlation with specific surface area. Moreover, it was found that the crystallinity of TiO2 has a moderate correlation with the photocatalytic activity of both crystal forms of TiO2. These results suggest that a degree of photocatalytic activity of TiO2 depends on the various physicochemical properties of each type of TiO2 investigated.     

HSulf-2, an extracellular endoglucosamine-6-sulfatase, selectively mobilizes heparin-bound growth factors and chemokines: effects on VEGF, FGF-1, and SDF-1

Background  

Heparin/heparan sulfate (HS) proteoglycans are found in the extracellular matrix (ECM) and on the cell surface. A considerable body of evidence has established that heparin and heparan sulfate proteoglycans (HSPGs) interact with numerous protein ligands including fibroblast growth factors, vascular endothelial growth factor (VEGF), cytokines, and chemokines. These interactions are highly dependent upon the pattern of sulfation modifications within the glycosaminoglycan chains. We previously cloned a cDNA encoding a novel human endosulfatase, HSulf-2, which removes 6-O-sulfate groups on glucosamine from subregions of intact heparin. Here, we have employed both recombinant HSulf-2 and the native enzyme from conditioned medium of the MCF-7-breast carcinoma cell line. To determine whether HSulf-2 modulates the interactions between heparin-binding factors and heparin, we developed an ELISA, in which soluble factors were allowed to bind to immobilized heparin.     

Kinetics of the thermal decompositions of MC2O4 to MCO3 (M=Ca,Sr AND Ba)

The kinetics of the thermal decompositions of CaC₂O₄, SrC₂O₄ and BaC₂O₄ to their carbonates were studied by thermogravimetry at constant and at linearly increasing temperatures. Isothermally, the three oxalates decompose according to A_1.43, R_1.54 and R₁ laws, respectively. Dynamically, the decompositions of the first two oxalates proceed in a similar way as under the isothermal conditions, whereas BaC₂O₄ decomposes according to a different law.Kinetic compensation laws were established for the decomposition of CaC₂O₄ and SrC₂O₄ under both isothermal and non-isothermal conditions. Such a compensation law is considered to result if correct kinetic model functionsF () are used when the isothermal and non-isothermal decompositions are regulated by the sameF().

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Zusammenfassung Die Kinetik der thermischen Zersetzung von CaC₂O₄, SrC₂O₄ und BaC₂O₄ zu den entsprechenden Carbonaten wurde durch Thermogravimetrie bei konstanter und linear ansteigender Temperatur untersucht. Isotherm werden die drei Oxalate entsprechend A_1.43, R_1.54 bzw. R₁ zersetzt. Dynamisch verläuft die Zersetzung der ersten zwei Oxalate auf ähnlichem Wege, während BaC₂O₄ nach einem davon verschiedenem Gesetz abgebaut wird. Kinetische Kompensationsgesetze wurden sowohl unter isothermen als auch unter nicht-isothermen Bedingungen für die Zersetzung von CaC₂O₄ und SrC₂O₄ ermittelt. Ein solches Kompensationsgesetz wird als Ergebnis eines solchen Vorgehens angesehen, bei dem richtige kinetische ModellfunktionenF() benutzt werden, wenn die nicht-isothermen Zersetzungen durch die gleichenF() bestimmt sind.

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- , . , , A_1.43, R_1.54 · R₁- , . , . F() «» , F().