A phase-field modeling of void swelling in the Austenitic stainless steel

Two-dimensional phase-field simulations of void swelling in the Austenitic stainless steel were performed for irradiated materials. A numerical model was established for void swelling with an implementation of the elasticity effect, and we examined the roles of the applied stress and grain boundary sink strength and Frenkel defect recombination in determining the void swelling rate. The obtained results were compared with the existing experimental observations.     

Polypropylene non-woven supported fibronectin molecular imprinted calcium alginate/polyacrylamide hydrogel film for cell adhesion

Fibronectin (FN) imprinted polypropylene (PP) non-woven supported calcium alginate/polyacrylamide hydrogel film (PP-s-CA/PAM MIP) was prepared using non-woven PP fiber as matrix, FN as template molecule, sodium alginate (SA) and acrylamide (AM) as functional monomers, via UV radiation-reduced polymerization. The PP-s-CA/PAM MIP exhibited an obvious improvement in terms of adsorption capacity for FN compared with non-imprinted polymer (NIP). The PP-s-CA/PAM MIP was successfully used for the culture of mouse fibroblast cells (L929) and the results showed that PP-s-CA/PAM MIP exhibited better cell adherence performance than the NIP did.     

1,8-Naphthalimide-based highly emissive luminogen with reversible mechanofluorochromism and good cell imaging characteristics

A 1,8-naphthalimide-based organic luminescent molecule has been designed and successfully synthesized via a Suzuki coupling reaction. The compound displayed a bright solid-state luminescence with the absolute fluorescence quantum yield up to 61.2%. Furthermore, the luminogen also exhibited reversible mechanofluorochromism behavior and good performance for cell imaging.     

Synthesis and Characterization of CPE-g-GMA Graft Copolymers Obtained by Suspension Copolymerization

Graft of glycidyl methacrylate (GMA) onto solid-state chlorinated polyethylene (CPE) has been performed by suspension copolymerization in a complex dispersion medium which was a compound with H₂O, ethyl acetate (EA) and tert-butyl alcohol (TBA). Benzoyl peroxide (BPO) was used as the free radical initiator. The graft level (graft degree and graft efficiency) was calculated gravimetrically, and the graft copolymer was characterized by infrared (IR) spectroscopy, thermogravimetric analysis (TGA) and contact angle study. The effects of reaction conditions on graft level, including chemical parameters (the concentration of monomer, initiator, and interfacial agent) and processing parameters (reaction time and temperature), have been investigated in detail. The experimental results showed that GMA could be grafted onto the chain of CPE with comparative higher graft degree, which could reach 37% with graft efficiency above 80%.     

Alkenyl‐functionalized precursors for renewable hydrogels design

A library of crosslinking chemistries for the hydrogel synthesis based on the hemicellulose acetylated galactoglucomannan (AcGGM) has been developed, demonstrated, and evaluated. A three‐step route was elaborated including (1) the carbonyldiimidazole activation of primary hydroxylated vinylic molecules such as acrylates, vinyl alcohols, and vinyl ethers, (2) the covalent coupling of the alkenyl precursors to the polysaccharide backbone hydroxyls, and (3) the radical crosslinking of pendant vinyl functionalities affording a hydrophilic network. Crosslinking strategies explored include redox initiation and photo initiation, with an effort to adapt the suggested synthesis routes to benign conditions. The different functionalization strategies were shown to influence the resulting gel's properties. Varying the crosslinking media was found to be a strong tool to tune the properties of the gels. Modifications were in all cases verified by means of NMR and FTIR, and the gels were characterized with respect to swelling capacity and rheological parameters. It was shown that by adjusting the synthesis parameters, the resulting properties of the AcGGM gels could be custom‐made for a given performance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3595–3606, 2009     

Measurement of electrophoretic mobility of cardiomyocytes

The electrophoretic mobility (EPM) of rat cardiomyocytes with or without the treatment of neuraminidase was studied by cell electrophoresis. The EPM was found to change over a range from 0 to 8.67 μm s^?1/V cm^?1, depending on ionic strength, transmembrane potential, pH value, and/or surface charges. It is interesting that zero EPM was observed but reverse of the mobility was not. These results suggested that the negative charges carried on the cardiomyocyte surface might comprehensively consist of surface sialic acid, plasmalemma proteins, phospholipids, and transmembrane potential. The aberrant electrical double layer formed between the carried negative charges and adions had a big adsorption layer and a diffusion layer whose sizes changed circularly, making only negative charges be carried on the surface of living cardiomyocytes. The special structures on the surface of cardiomyocytes probably play a considerable role in the process of cardiac electrical activity.     

Naphthalene‐based poly(arylene ether ketone) copolymers containing sulfobutyl pendant groups for proton exchange membranes

A new monomer 1,5‐bis(4‐fluorobenzoyl)‐2,6‐dimethoxynaphthalene (DMNF) was prepared and further polymerized to form naphthalene‐based poly(arylene ether ketone) copolymers containing methoxy groups (MNPAEKs). The side‐chain‐type sulfonated naphthalene‐based poly(arylene ether ketone) copolymers (SNPAEKs) were obtained by demethylation and sulfobutylation. Flexible and tough membranes with reasonably high mechanical strength were prepared. The SNPAEKs membrane showed anisotropic membrane swelling with larger swelling in thickness than in plane. Transmission electron microscopy (TEM) analysis revealed clear nanophase separated structure of SNPAEKs membranes, which composed of hydrophilic side chain and hydrophobic main‐chain domains. Proton conductivities of copolymers increased gradually with increase in temperature. The highest conductivity of 0.179 S/cm was obtained for SNPAEK‐80 (IEC = 1.82 mequiv/g) at 80 °C, which is higher than that of Nafion117 (0.146 S/cm). The SNPAEKs membranes exhibit the methanol permeability in the range of 3.42 × 10^?8?4.49 × 10^?7 cm²/s, which are much lower than that of Nafion117. They could be the promising materials as alternative to Nafion membrane for direct methanol fuel cells applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47:5772–5783, 2009     

Tissue surface tension measurement by rigorous axisymmetric drop shape analysis

Certain behaviours of embryonic cell aggregates can be modelled by ascribing to them a tissue surface tension, with each cell analogous to a liquid molecule. Under normal gravity, aggregates are nearly spherical, but they can be partially flattened in a centrifuge. This allows measurement of their tissue surface tensions by a drop shape method such as axisymmetric drop shape analysis (ADSA). We study ectodermal embryonic cells from the frog Xenopus laevis subjected to centrifugation at 100 × g and 200 × g. We show that ADSA can be applied to irregular aggregate profiles and compare results with those from a previous, simpler version called ADSA-IP. With a modification in the experimental method, the two algorithms give similar results and the aggregate profiles more closely follow Laplacian curves. The ADSA fitting error allows an estimate of the relative uncertainty in the results.     

Swelling behaviors of sub‐micron‐sized copolymer gel particles: The effect of physical crosslinking

The swelling equilibria model of copolymer gel particles is proposed. It accounts for physical crosslinking as a result of hydrogen bonding. The modified Flory–Erman model is used to describe the elastic contribution to swelling. The model considers hydrogen bonding as a physical crosslinker. A free‐energy‐of‐mixing term is represented using the extended Flory–Huggins theory. The interaction parameter χ in the model is a function of both composition and temperature. We then compare the proposed model with the swelling behaviors of copolymer gel particles. Our model offers fairly good agreement with the experimental data for given systems. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1928–1934, 2001     

Organic–inorganic hybrid hydrogels involving poly(N‐isopropylacrylamide) and polyhedral oligomeric silsesquioxane: Preparation and rapid thermoresponsive properties

3‐Acryloxypropylhepta(3,3,3‐trifluoropropyl) polyhedral oligomeric silsesquioxane (POSS) was synthesized and used as a modifier to improve the thermal response rates of poly(N‐isopropylacrylamide) (PNIPAM) hydrogel. The radical copolymerization among N‐isopropylacrylamide (NIPAM), the POSS macromer and N,N′‐methylenebisacrylamide was performed to prepare the POSS‐containing PNIPAM cross‐linked networks. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) showed that the POSS‐containing PNIPAM networks displayed the enhanced glass transition temperatures (T_g's) and improved thermal stability when compared with plain PNIPAM network. The POSS‐containing PNIPAM hydrogels exhibited temperature‐responsive behavior as the plain PNIPAM hydrogels. It is noted that with the moderate contents of POSS, the POSS‐containing PNIPAM hydrogels displayed much faster response rates in terms of swelling, deswelling, and re‐swelling experiments than plain PNIPAM hydrogel. The improved thermoresponsive properties of hydrogels have been interpreted on the basis of the formation of the specific microphase‐separated morphology in the hydrogels, that is, the POSS structural units in the hybrid hydrogels were self‐assembled into the highly hydrophobic nanodomains, which behave as the microporogens and promote the contact of PNIPAM chains and water. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 504–516, 2009