Biocatalytic synthesis of highly ordered degradable dextran-based hydrogels

We have prepared unique macroporous and ordered dextran-based hydrogels using a single-step biocatalytic transesterification reaction between dextran and divinyladipate in neat dimethylsulfoxide. These hydrogels show a unimodal distribution of interconnected pores with average diameters from 0.4 to 2.0 [mu]m depending on the degree of substitution. In addition, the hydrogels show a higher elastic modulus for a given swelling ratio than chemically synthesized dextran-based hydrogels. In vivo studies in rats show that the hydrogel networks are degradable over a range of time scales from 5 to over 40 days, and possess good biocompatibility, as reflected in only a mild inflammatory reaction and minor fibrous capsule formation during the time-frame of subcutaneous implantation. These combined properties may offer competitive advantages in biomedical applications ranging from tissue engineering to controlled drug delivery.http://www.sciencedirect.com/science/article/B6TWB-4F7Y94V-3/1/0d83788c215a34850e13d6d76d3bba8

Dextrin and conducting polymer containing biocomposites: properties and behavior as cellular matrix

Both α-cyclodextrin and linear dextrin are used to prepare biocomposites with poly(3,4- ethylenedioxythiophene). Materials are prepared electrochemically in aqueous solution. Comparison with the pure polymer indicates that the electroactivity and electrostability decrease with the incorporation of the dextrins while the electrical conductivity is retained. The different properties of the two biocomposites suggest that the linear dextrin is mainly located at the surface, whereas the cyclodextrin is homogeneously distributed in the polymeric matrix. Cell adhesion and proliferation assays indicate that the cellular activity is significantly higher in the dextrin-containing biocomposites.Acknowledgements: Financial support from the MICINN and FEDER (MAT2009-09138) and Generalitat de Catalunya (research group 2009 SGR 925 and XRQTC) is gratefully acknowledged. B.T.-D. acknowledges support from the MICINN through an FPI grant and financial support for his stay at the 3B’s Research Group (Portugal). The support from project PTDC/FIS/115048/2009 (FCTPortugal) is also acknowledged. Authors are indebted to Dr. Elaine Armelin for helpful suggestions and to David Aradilla for assistance in electrical measures and SEM micrographs. Support for the research of C.A. was received through the prize ‘‘ICREA Academia’’ for excellence in research funded by the Generalitat de Catalunya

Self-assembled nanogel made of mannan : synthesis and characterization

Amphiphilic mannan (mannan-C16) was synthesized by the Michael addition of hydrophobic 1-hexadecanethiol (C16) to hydroxyethyl methacrylated mannan (mannan-HEMA). Mannan-C16 formed nanosized aggregates in water by selfassembly via the hydrophobic interaction among C16molecules as confirmed by hydrogen nuclearmagnetic resonance (1H NMR), fluorescence spectroscopy, cryo-field emission scanning electron microscopy (cryo-FESEM), and dynamic light scattering (DLS). The mannan-C16 critical aggregation concentration (cac), calculated by fluorescence spectroscopy with Nile red and pyrene, ranged between 0.04 and 0.02mg/mL depending on the polymer degree of substitution ofC16 relative to methacrylated groups. Cryo-FESEM micrographs revealed that mannan-C16 formed irregular spherical macromolecular micelles, in this work designated as nanogels, with diameters ranging between 100 and 500 nm. The influence of the polymer degree of substitution, DSHEMA andDSC16, on the nanogel size and zeta potential was studied byDLS at different pH values and ionic strength and as a function of mannan-C16 and urea concentrations. Under all tested conditions, the nanogel was negatively charged with a zeta potential close to zero. Mannan-C16 with higher DSHEMA and DSC16 values formed larger nanogels andwere also less stable over a 6month storage period and at concentrations close to the cac.When exposed to solutions of different pH and aggressive conditions of ionic strength and urea concentration, the size of mannan-C16 varied to some extent but was always in the nanoscale range.International Iberian Nanotechnology Laboratory (INL)Fundação para a Ciência e a Tecnologia (FCT

Sexual delinquency and Exploitation

ARTICLES: : 1. Editorial 2. Donald West - The Sex Crime Situation: Deterioration more Apparent than Real? 3. Roxanne Lieb - Social Policy and Sexual Offenders: Contrasting United States' and European Policies 4. Hans Boutellier - The Pornographic Context of Sexual Delinquency: Reflections on the Contemporary Sexual Mentality 5. Martin Killias - The Emergence of a New Taboo: The Desexualisation of Youth in Western Society since 1800 6. Sarah Alexander, Stan Meuwese and Annemieke Wolthuis - Policies and Developments relating to the Sexual Exploitation of Children: The Legacy of the Stockholm Conference 7. Stefan Bogaerts, Geert Vervaeke and Johan Goethals - Research on Predictors for Sexual Delinquence 8. Frans van Dijk and Jaap de Waard - Current issues: Key Findings from the Study Legal Instrastructure of the Netherlands in International Perspective: Crime Contro

Теплофизические свойства криопротекторов. II. Динамическая вязкость ряда криопротекторов, их растворов и смесей

Систематизированы данные разных литературных источников и выведены полиномиальные уравнения для расчета динамической вязкости воды, 21 чистого криопротектора и водных растворов трех криопротекторов различной концентрации в зависимости от температуры. Получены эмпирические зависимости для расчета динамической вязкости водных растворов NaCl и KCl, водных растворов 38 криопротекторов и 18 смесей некоторых криопротекторов от концентрации при разных температурах.Систематизовано дані різних літературних джерел і виведено поліноміальні рівняння для розрахунку динамічної в’язкості води, 21 чистого кріопротектора і водних розчинів трьох кріопротекторів різної концентрації в залежності від температури. Отримано емпіричні залежності для розрахунку динамічної в’язкості водних розчинів NaCl і KCl, водних розчинів 38 кріопротекторів і 18 сумішей деяких кріопротекторів від концентрації при різних температурах.The article represent summarized literature data and derivation of polynomial equations to calculate the dynamics viscosity of water, 21 pure cryoprotective agents and aqueous solutions of three cryoprotective agents in different concentrations depending on temperature. Empirical equations for various concentration and temperatures were obtained to calculate dynamic viscosity of aqueous solutions of NaCl and KCl, aqueous solutions of 38 cryoprotective agents and 18 mixtures of some cryoprotectants

Rapid Self‐Integrating, Injectable Hydrogel for Tissue Complex Regeneration

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112267/1/adhm201500093.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112267/2/adhm201500093-sup-0001-S1.pd

ОЦІНКА СТАНУ ДЛЯ СИСТЕМИ З РОЗПОДІЛЕНИМИ ПАРАМЕТРАМИ

В даній статті розглядається задача — оцінка стану для системи з розподіленими параметрами. Оцінка стану проводиться за нагрівом довгого тонкого стрижня. Для аналізу системи використовується модальне подання. Дана задача дає змогу оцінити у значній мірі кількість точок вимірювань та отримати матрицю спостережуваності

Cationic and reactive primary amine-stabilised nanoparticles via RAFT aqueous dispersion polymerisation

The synthesis of primary amine-functionalised diblock copolymer nanoparticles via polymerisation-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerisation formulation is reported. The primary amine steric stabiliser is a macromolecular chain transfer agent (macro-CTA) based on 2-aminoethyl methacrylate AMA, which can be readily polymerised in its hydrochloride salt form with good control (Mw/Mn < 1.30) using RAFT aqueous solution polymerisation. Subsequent chain extension of this macro-CTA with 2-hydroxypropyl methacrylate (HPMA) leads to the formation of relatively monodisperse spherical nanoparticles (68 to 288 nm) at pH 6. However, worms or vesicles could not be obtained, because strong lateral repulsion between the highly cationic PAMA stabiliser chains impedes the formation of these higher order copolymer morphologies. Deprotonation of the primary amine stabiliser chains at or above pH 9 results in flocculation of these spherical nanoparticles as the PAMA block becomes uncharged. Diblock copolymer spheres, worms or vesicles can be synthesised that remain stable at pH 9 by supplementing the PAMA macro-CTA with a poly(glycerol monomethacrylate) (PGMA) macro-CTA, since this non-ionic block confers effective steric stabilisation in alkaline media. A series of diblock copolymer nanoparticles with the general formula ([1 − n]PGMAx + nPAMAy)–PHPMAz can be synthesised by optimising: (i) the mean degree of polymerisation (DP, or x) of the PGMA block, (ii) the PHPMA core-forming DP (or z); (iii) the mol fraction (n) of the PAMA stabiliser; and (iv) the copolymer concentration. These spheres, worms and vesicles are both cationic at low pH and colloidally stable at high pH. Furthermore, deprotonation of the protonated primary amine groups on the PAMA stabiliser chains at high pH renders these particles susceptible to epoxy-amine conjugation. This is demonstrated by the reaction between the primary amine groups on (0.8PGMA101 + 0.2PAMA96)–PHPMA1000 diblock copolymer spheres, and epoxide-functionalised diblock copolymer nanoparticles in aqueous solution at pH 8