Proanthocyanidin metabolites associated with dietary fibre from in vitro colonic fermentation and proanthocyanidin metabolites in human plasma

Proanthocyanidins (PAs) or condensed tannins, a major group of dietary polyphenols, are oligomers and polymers of flavan‐3‐ol and flavan‐3, 4‐diols widely distributed in plant foods. Most literature data on PAs' metabolic fate deal with PAs that can be extracted from the food matrix by aqueous‐organic solvents ( extractable proanthocyanidins). However, there are no data on colonic fermentation of non‐extractable proanthocyanidins (NEPAs), which arrive almost intact to the colon, mostly associated to dietary fibre (DF). The aim of the present work was to examine colonic fermentation of NEPAs associated with DF, using a model of in vitro small intestine digestion and colonic fermentation. Two NEPA‐rich materials obtained from carob pod (Ceratonia siliqua L. proanthocyanidin) and red grapes (grape antioxidant dietary fibre) were used as test samples. The colonic fermentation of these two products released hydroxyphenylacetic acid, hydroxyphenylvaleric acid and two isomers of hydroxyphenylpropionic acid, detected by HPLC‐ESI‐MS/MS. Differences between the two products indicate that DF may enhance the yield of metabolites. In addition, the main NEPA metabolite in human plasma was 3,4‐dihydroxyphenyl acetic acid. The presence in human plasma of the same metabolites as were detected after in vitro colonic fermentation of NEPAs suggests that dietary NEPAs would undergo colonic fermentation releasing absorbable metabolites with potential healthy effects.     

Synthesis and crystal structure of the singly tucked-in derivative of bis(phenyltetramethylcyclopentadienyl)titanium

Thermolysis of [TiMe₂(η⁵-C₅Me₄Ph)₂] (4) at 145 °C for 5 h afforded the singly tucked-in paramagnetic titanocene [Ti(III)(η⁵-C₅Me₄Ph){η⁵:η¹-C₅Me₃Ph(CH₂)}] (9). In distinction to the singly tucked-in permethyltitanocene [Ti(III)(η⁵-C₅Me₅){η⁵:η¹-C₅Me₄(CH₂)}] (1) which was found crystallographically disordered [J.M. Fischer, W.E. Piers, V.G. Young, Jr., Organometallics 15 (1996) 2410] the single crystal X-ray diffraction analysis of 9 afforded molecular parameters with nearly by one order better precision as measured by esd-values.     

In‐vitro study on the efficacy of tannin fractions of edible nuts as antioxidants

Tannin fractions were isolated from crude acetonic extracts of defatted walnut, hazelnut and almond kernels using Sephadex LH‐20 column chromatography. The obtained material was characterized by content of total phenolics and electrophoretic separations using capillary zone electrophoresis (CZE). The antioxidant activities of the tannin fractions were analyzed by several methods: DPPH and ABTS assays, photochemiluminescence (PCL) method, as well as in two lipid model systems: emulsion with β‐carotene‐linoleic acid and L ‐α‐lecithin liposomes. The contents of total phenolics in the tannin fractions of walnuts, hazelnuts and almonds were 550, 329 and 83 mg catechin eq/g, respectively. The electrophoretic profiles of hazelnut and almond tannin fractions were similar, in contrast to the walnut profile. All analyzed fractions exhibited strong antioxidant properties. The antioxidant capacity of lipid‐soluble (ACL) compounds determined by PCL method was the highest for the fraction isolated from walnuts – 7.35 mmol Trolox eq/g. The DPPH radical and the ABTS radical cation were scavenged by the walnut tannin fraction with a higher efficacy than by the two other fractions. EC₅₀ values of the DPPH method were 1.8 times higher for the hazelnut fraction and 2.3 times higher for the almond fraction when compared to the walnut tannins. In turn, the total antioxidant activity values were 8.17, 2.82 and 1.98 mmol Trolox eq/g for the walnut, hazelnut and almond fractions, respectively. On the other hand, in both lipid models applied, lower antioxidant activity of walnut tannins than of hazelnut tannins was noted. The antioxidant effect of almond tannins was weaker or similar than that of walnut tannins in the β‐carotene‐linoleic acid emulsion and the L ‐α‐lecithin liposomal system, respectively.     

Colour constancy of vat prints on cotton fabrics

Colour constancy of prints with vat dyes on cotton fabrics was investigated by computing the CMCCON02 colour inconstancy index with the key element CAT02 for chromatic adaptation transform. The results show that the highest changes in colour appearance can be expected when the average daylight is replaced with fluorescent light. If D65 daylight is replaced with some other type of daylight, such as D50 or D55, only minor colour deviations occur which do not substantially change the colour appearance of the prints. The analysis of the influence of the lightness and chromaticity of prints shows that the chromaticity of the samples significantly affects their colour constancy. The change of appearance of the prints with lower chroma because of changed illumination conditions is less probable. The influence of a dye blend composition was also investigated. On average, multi‐coloured dye blends have proved to be more colour constant.     

A comparative study on the electrical and mechanical behaviour of multi‐walled carbon nanotube composites prepared by diluting a masterbatch with various types of polypropylenes

Polypropylene (PP) nanocomposites with multi‐walled carbon nanotubes (CNT) were produced by a small‐scale masterbatch melt dilution technique using five PP differing in melt flow index (MFI) and degree of maleination. PP used in a masterbatch has MFI = 12 (PP₁₂), the others used PP which have MFI = 2 or MFI = 8. The state of CNT dispersion as assessed by melt rheological and morphological investigations indicated a better dispersion when using unmodified PP with MFI = 8 (PP₈) and the masterbatch's PP₁₂. Electrical conductivity results showed nanotube percolation at contents between 1.1 and 2.0 vol %, whereas lower values were obtained for the matrices with the best dispersion, i.e., PP₈ and PP₁₂. The dependencies of the relative Young's modulus on the CNT content showed that the maleinization improved the interfacial interactions between the components, especially in the case of maleated PP with MFI = 8 (PP‐MA₈), but the better dispersion was prevented by the incompatibility between polar groups of PP‐MA and the nonpolar origin masterbatch PP₁₂. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mass transfer in vertical liquid-solids flow of coarse particles

Wall-to-bed mass transfer in the hydraulic transport of spherical glass particles was studied. The experiments were performed by transporting spherical glass particles 1.20, 1.94 and 2.98 mm in diameter with water in a 25.4 mm I.D. tube. The mass transfer coefficients were determined by following rate of dissolution of a segment of the transport tube prepared from benzoic acid.In the runs in hydraulic transport, the Reynolds number of the tube varied between 1826 and 27597. The loading ratio (G_p/G_f) was between 0.026 and 0.474, and the fluid superficial velocity was between 0.267 · U_t and 4.904 · U_t, where U_t represents the single particle terminal velocity. For these ratios, the voidage ranged from 0.7123 to 0.9228.Also, wall-to-bed mass transfer in the single phase flow regime was studied. In the runs without particles, the Reynolds number of the tube varied between 122 and 39132. The data for the mass transfer factor (j_D) in single phase flow are correlated for turbulent flow regime, using the Chilton-Colburn's type equations, j_D = f(Re). Those investigations were conducted in aim to compare with results for wall-to-bed mass transfer in hydraulic transport.The data for wall-to-bed mass transfer (j_D) in hydraulic transport of spherical particles were correlated by treating the flowing fluid-particle suspension as a pseudofluid, by introducing a modified suspension-wall friction coefficient (f_w) and a modified Reynolds number (Re_m). The data for wall-to-bed mass transfer in the hydraulic transport of particles show that an analogy between mass and momentum transfer exists.     

A deuterium–palladium electrode as a new sensor in non-aqueous media: the potentiometric titration of weak acids in alcohols

A deuterium–palladium electrode was employed as a new indicator electrode for the titration of weak acids in tert-butanol and iso-propanol. The investigated electrode showed a linear dynamic response for p-toluenesulfonic acid in the concentration range from 0.1 to 0.001 mol L⁻¹, with a Nernstian slope of 53.0 mV per decade in tert-butanol. The potential in the course of the titration and at the titration end-point (TEP) was rapidly established. Potassium hydroxide and tetrabutylammonium hydroxide (TBAH) proved to be very suitable titrating agents for these titrations. The response time was less than 10–11 s and the lifetime of the electrode was limitless. The experimental results obtained for the proposed electrochemical sensor and a conventional glass electrode were in good agreement. The advantages of the electrode are long-term stability, fast response, reproducibility, and easy preparation.     

Behaviour of bone origin hydroxyapatite at elevated temperatures and in O2 and CO2 atmospheres

In the present work the behaviour of HAp extracted from pig bones at elevated temperatures up to 1000 °C in O₂ and CO₂ atmospheres has been studied. It has been found that CO₂ atmosphere arrests HAp decomposition. Chemical analysis and infrared spectroscopy reveal that no free CaO appears and no decrease of CO₃⁻² group concentration occurs in the material calcined in CO₂ atmosphere. In the O₂ atmosphere at elevated temperatures, CaO and CO₂ are emitted from the samples, although the remaining material retains the HAp structure as indicated by the X-ray diffraction.     

Investigation of mechanism of Al(OH)3 crystal growth

Crystallization of Al(OH)₃ that occurs during the decomposition of caustic soda solutions is an important part of Bayer process for alumina production. Several phenomena, which influence the physicochemical characteristics of precipitated Al(OH)₃, occur simultaneously during this process. They are nucleation, agglomeration, and crystal growth of Al(OH)₃. In this article, we have investigated the mechanism of Al(OH)₃ crystal growth from pure caustic soda solutions and in the presence of oxalic acid. The results have shown that the growth of Al(OH)₃ crystals from caustic soda solutions follow the B + S model (birth and spread). New Al(OH)₃ particles, formed during the decomposition process of pure caustic soda solutions, are characterized by regular hexagonal shape. The nuclei have the same geometry as the contact face. However, microstructural investigations of Al(OH)₃ samples, obtained by crystallization from caustic soda solutions in the presence of oxalic acid, have shown the presence of nuclei of irregular shape in addition to regular ones. So, the presence of oxalic acid in the caustic soda solutions leads to a change in crystal habit. Besides, the results obtained by kinetic investigation confirmed the mentioned mechanism of Al(OH)₃ crystal growth.     

Fire analysis of timber composite beams with interlayer slip

The purpose of this paper is to model the behaviour of timber composite beams with interlayer slip, when simultaneously exposed to static loading and fire. A transient moisture-thermal state of a timber beam is analysed by the Luikov equations, and mechanical behaviour of timber composite beam is modelled by Reissner's kinematic equations. The model can handle layers of different materials. Material properties are functions of temperature. The thermal model is validated against the experimental data presented in the literature. Generally, the model provides excellent agreement with the experimental data. It is shown that the material properties of timber play an important role in the fire resistance analysis of timber structures when exposed to fire.