The Effects of Beating,Web Forming and Sizing on the Surface Energy of <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> Kraft Fibres Evaluated by Inverse Gas Chromatography

In this work attention has been focused on the effects of papermaking beating, web forming and sizing operations on the physical/chemical surface properties of bleached Eucalyptus globulus kraft fibres. Inverse gas chromatography (IGC) was used to determine the dispersive component of surface tension (γ_s^d) as well as the acidic/basic character (according to the Lewis concept) of the solid surfaces (pulp fibres and pulp handsheets). The results have shown that the main effect of beating is to increase the fibre's Lewis acidic character. Web forming caused a strong decrease in γ_s^d and significant increments in the adhesion works of both acidic and basic probes, lowering the ratio between the two. Nevertheless, the surface of handsheets still exhibited a dominant acidic character. The sizing operation did not change the dispersive component of the surface tension significantly but decreased the difference between the adhesion works of the acidic and basic probes, rendering the handsheet surface less Lewis acidic and more Lewis basic. Thus, although internal sizing is expected to strongly influence liquid spreading at the paper surface and liquid penetration of the fibre's network, it is concluded that beating and web forming lead to important changes in the surface energetic properties of the Eucalyptus globulus kraft fibres.     

Solution structure of a beta-peptide ligand for hDM2

We recently reported a beta-peptide foldamer, beta53-1, that folds into a 14-helix in aqueous solution, binds the oncoprotein hDM2 with submicromolar affinity, and potently inhibits the interaction of hDM2 with a peptide derived from the activation domain of p53 (p53AD). Here, we present the solution structure of beta53-1 in methanol. Details of the structure illustrate fundamental and novel elements of beta-peptide folding and recognition. These elements include the detailed arrangement of a complex, 14-helix-stabilizing salt bridge on one helical face, and a unique "wedge into cleft" packing interaction along a second. The structure also reveals how a subtle distortion in the beta53-1 14-helix geometry alters the presentation of its recognition epitope, rendering it particularly well suited for alpha-helix mimicry. The solution structure of beta53-1 demonstrates that well folded beta-peptide oligomers can effectively present an extended, highly variable surface that could be used as a general platform for targeting critical protein-protein interfaces.     

Synthesis and properties of enamines of the phenanthridine series

We have synthesized secondary and tertiary enamines, derivatives of 1,2,3,4,4a,5,6,10b-octahydrophenanthridine, and we have considered the Z,E-isomerism of the enaminoesters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1374–1377, October, 1993.     

Isolation of preparations with a high content of eicosapentaenoic acid from the red marine alga Palmaria stenogona

The composition is given of the fatty acids of the red marine algaPalmaria stenogona. The amount of eicosapentaenoic acid (EPA) in the alga was 69.9–77.0% of the total fatty acids. The procedure for isolating EPA of 80–90% purity from the alga is described which includes the saponification of the algal lipids, the selective extraction of the unsaponifiable lipids, the isolation of the free fatty acids, and their separation by the method of crystallizing inclusion complexes of the fatty acids with urea. Institute of Marine Biology, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 330–333, May–June, 1990.     

Assessment of the retention properties of poly(vinyl alcohol) stationary phase for lipid class profiling in liquid chromatography

Potentialities of polymerized vinyl alcohol on silica gel were assessed for class separation of simple lipids, sphingolipids, glyceroglycolipids and phospholipids by high-performance liquid chromatography. A screening of pure solvents in binary gradient elution and a chemometric approach was used to define a rugged two segment linear gradient formed from four solvents for total lipid class separation. Triethylamine and formic acid were added in all mobile phase components for acidic phospholipid separation and evaporative light scattering response enhancement. Simple analytical procedures are described for the analysis of complex lipid materials.     

Crystal structure of oxotitanium(IV) 2,2,6,6-tetramethyl-3,5-heptanedionate

The structure of titanyl dipivalylmethanate TiO(dpm)₂ has been studied by X-ray diffraction analysis. The compound has a molecular structure formed by isolated centrosymmetrical dimers [TiO(dpm)₂]₂; the unit cell contains two structurally related, crystallographically unique binuclear molecules. The Ti...Ti distance in the dimer is 2.73 Å. Crystal data for Ti₂C₃₆H₇₆O₁₀: a = 32.477(6) Å, b = 14.409(3) Å, c = 25.630(5) Å; β = 107.82(3)°, space group C2/c, Z = 8, d _calc = 1.002 g/cm³.     

THE FLUORESCENT PRODUCT OF SCALEWORM BIOLUMINESCENT REACTION: AN IN VITRO STUDY

Abstract— The fluorescence of scaleworms has been attributed by Harvey (1952) to a product of the bioluminescent reaction confined in the scales of these worms. We have purified this fluorescent molecule by gel filtration. This compound has an apparent low molecular weight as shown by polyacrylamide gel clectrophoresis in the presence of SDS. The yield of the fluorescent product, after gel filtration, varies with the stimulation of the bioluminescence, triggered either chemically or enzymatically. The fluorescence spectrum of the purified product is similar to the one observed in vivo , with a maximum centered at 520 nm. Consequently, the fluorescent compound isolated is likely the reaction product of the bioluminescent reaction.     

Copolymers of the C9 hydrocarbon fraction of liquid pyrolysis products with maleic anhydride and their esterification products as additives to paper pulp

The influence exerted by copolymers of the C₉ fraction of liquid pyrolysis products of petroleum raw materials with maleic anhydride and by their esterification products, added to paper pulp, on the main paper properties was examined.     

MONOFUNCTIONAL3,4-and4',5'-PHOTOCYCLOADDUCTS BETWEEN 4,5'-DIMETHYLANGELICIN and THYMINE

By irradiating (365 nm) an aqueous liquid solution of 4,5'-dimethylangelicin. a monofunctional photosensitizing furocoumarin, in the presence of an excess of thymine, two new compounds, I and II, have been obtained; they do not show fluorescence when observed with Wood's light. The nuclear magnetic resonance data, the marked similarity of UV absorption and fluorescence spectra of these compounds with those of synthetic 3.4-dihydro-4,5'-dimethylangelicin and their capacity to undergo photodissociation (254 nm) yielding the starting thymine and 4,5'-dimethylangelicin in equimolecular amounts, are consistent with C₄-cycloadducts between the 3,4-double bond of the furocoumarin and 5,6-double bond of thymine. Nuclear magnetic resonance data indicate for I and II a head-to-head and a head-to-tail structure, respectively. When irradiation is carried out in the frozen state, two adducts. III and IV, fluorescent at Wood's light, have been obtained other than the two above-mentioned compounds I and II. Compounds III and IV have been identified as 4'.5'-fluorescent adducts between the 4',5'-double bond of the furocoumarin and the 5.6-double bond of thymine; one of them (III) is identical to that formed in the photoreaction between DNA and 4,5'-dimethylangelicin; for this last compound a cis head-to-head structure has been suggested.