Summary: To develop ionic polymer‐metal composites (IPMC) with improved performance, three new ion‐exchange membranes were prepared and employed in IPMC construction. The membranes were prepared by radiation‐grafting of polystyrene sulfonic acid onto three fluoropolymers; poly(vinylidenefluoride‐co‐hexafluoropropylene), poly(ethylene‐co‐tetrafluoroethylene), and poly(tetrafluoroethylene‐co‐hexafluoropropylene). The bending displacements of the IPMCs constructed with these membranes were at least several times larger than that of Nafion IPMC of similar thickness without straightening‐back. The larger displacement was considered to be due to the higher concentration of ionic groups and consequent larger ion‐exchange capacity.
Actuation of (a) Nafion IPMC and (b) IPMC prepared in this study. 相似文献
Stable isotope ecology typically involves sacrificing the animal to obtain tissues. However, with threatened species or in long-term longitudinal studies, non-lethal sampling techniques should be used. The objectives of this study were to (1) determine if caudal fin tissue could be used as a non-lethal proxy to liver and muscle for stable isotope analysis, and (2) assess the effects of ethanol preservation on δ15N and δ13C in fin tissue of juvenile yellow perch Perca flavescens. The δ13C of caudal fin was not significantly different from liver (t23?=??0.58; p?=?0.57), and was more correlated with δ15N in liver (r2?=?0.78) than muscle (r2?=?0.56). Ethanol preservation enriched 15N and 13C for caudal fins, but by using our developed regression models, these changes in δ15N and δ13C can now be corrected. Overall, caudal fin tissue is a more reliable proxy to liver than muscle for δ15N and δ13C in yellow perch. 相似文献
In this study, an analytical method was developed for quantification of residues of the anthelmintic drug phenothiazine (PTZ) in pork muscle using liquid chromatography–tandem mass spectrometry. Muscles were extracted using 0.2% formic acid and 10 mm ammonium formate in acetonitrile, defatted and purified using n ‐hexane. The drug was well separated on a Waters XBridge™ C18 analytical column using a binary solvent system consisting of 0.2% formic acid and 10 mm ammonium formate in ultrapure water (A) and acetonitrile (B). Good linearity was achieved over a six‐point concentration range in matrix‐matched calibration with determination coefficient =0.9846. Fortified pork muscle having concentrations equivalent to and double the limit of quantification (1 ng/g) yielded recovery ranges between 100.82 and 104.03% and relative standard deviations <12%. Samples (n = 5) collected from large markets located in Seoul City tested negative for PTZ residue. In conclusion, 0.2% formic acid and ammonium formate in acetonitrile can effectively extract PTZ from pork muscle without solid‐phase extraction, a step normally required for cleanup before analysis and the validated method can be used for routine analysis to ensure the quality of animal products. 相似文献
The swelling of myofibrils extracted from white bovine muscle was followed by measuring their suspension rheology. Swelling of the myofibril with increasing pH and ionic strength was accompanied by an increase in both the steady shear viscosity of the suspension and the dynamic viscoelastic properties. Swelling was continuously monitored by measuringG while the ionic strength of the suspension was being changed by dialysis. The relationship between the degree of swelling and the rheological parameters is complicated because myofibrils are rodshaped and swell radially and therefore swelling results in a change in shape. To allow for this an attempt was made to generalize the data by plotting viscosity andG againstcS/øm, wherec is the protein concentration in the suspension,S is the swollen volume of the myofibrils per weight of protein, and øm is the maximum packing fraction.The best fit to the data was represented by the equations
sp = 1.05 (cS/m – 0.84)1.23 Pa · sG = 8.78 (cS/m – 0.67)2.22 N m–2. The scatter was greatest forG, possibly because at low degrees of shear the myofibrils were associated and this was confirmed by optical microscopy. Pronounced non-Newtonian behavior was observed and it was suggested that this was due to the disruption of aggregate structures, although at low concentration, orientation of the rods in the shear field may also be important. 相似文献
A combined sulfated silk fibroin scaffold is fabricated by modifying a knitted silk scaffold with sulfated silk fibroin sponges. In vitro hemocompatibility evaluation reveals that the combined sulfated silk fibroin scaffolds reduce platelet adhesion and activation, and prolong the activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). The response of porcine endothelial cells (ECs) and smooth muscle cells (SMCs) on the scaffolds is studied to evaluate the cytocompatibility of the scaffolds. Vascular cells are seeded on the scaffolds and cultured for 2 weeks. The scaffolds demonstrate enhanced EC adhesion, proliferation, and maintenance of cellular functions. Moreover, the scaffolds inhibit SMC proliferation and induce expression of contractile SMC marker genes.
This is the first ligase chain reaction used for diagnosis of spinal muscular atrophy (SMA). Universal fluorescent tri-probe ligation (UFTPL), a novel strategy used for distinguishing the multi-nucleotide alternations at single base, is developed to quantitatively analyze the SMN1/SMN2 genes in diagnosis of SMA. Ligase chain reaction was performed by adding three probes including universal fluorescent probe, connecting probe and recognizing probe to differentiate single nucleotide polymorphisms in UFTPL. Our approach was based on the two UFTPL products of survival motor neuron 1 (SMN1) and SMN2 genes (the difference of 9 mer) and analyzed by capillary electrophoresis (CE). We successfully determined various gene dosages of SMN1 and SMN2 genes in homologous or heterologous subjects. By using the UFTPL-CE method, the SMN1 and SMN2 genes were fully resolved with the resolution of 2.16 ± 0.37 (n = 3). The r values of SMN1 and SMN2 regression curves over a range of 1–4 copies were above 0.9944. Of the 48 DNA samples, the data of gene dosages were corresponding to that analyzed by conformation sensitive CE and denatured high-performance liquid chromatography (DHPLC). This technique was found to be a good methodology for quantification or determination of the relative genes having multi-nucleotide variants at single base. 相似文献
Graphene oxide (GO)‐based materials have been explored in biomedical applications as active engineered materials for diagnosis and therapy. Although a large number of studies have been carried out in the last years, aspects involving the orientation and elongation of cells on GO immobilized on polymeric nanofibers are still scarce. We investigated the interactions between skeletal muscle cells and GO immobilized on random and aligned electrospun nanofibers of poly(caprolactone) (PCL), a biocompatible and biodegradable polymer. Oxygen plasma was employed to modify the nanofiber polymer surface to enhance the interactions between the PCL fibers and GO. Scanning electron microscopy and confocal microscopy revealed the morphology and orientation of skeletal muscle cells (C2C12 cells) on random and aligned GO/PCL nanofibers. The approach employed here is useful to investigate the interaction of skeletal muscle cells with biocompatible polymer nanofibers modified with GO intended for cell scaffolds and tissue engineering. 相似文献
It is reported that low concentration of amphiphilic triblock copolymers of pMeOx‐b‐pTHF‐b‐pMeOx structure (TBCPs) improves gene expression in skeletal muscle upon intramuscular co‐injection with plasmid DNA. Physicochemical studies carried out to understand the involved mechanism show that a phase transition of TBCPs under their unimer state is induced when the temperature is elevated from 25 to 37 °C, the body temperature. Several lines of evidences suggest that TBCP insertion in a lipid bilayer causes enough lipid bilayer destabilization and even pore formation, a phenomenon heightened during the phase transition of TBCPs. Interestingly, this property allows DNA translocation across the lipid bilayer model. Overall, the results indicate that TBCPs exhibiting a phase transition at the body temperature is promising to favor in vivo pDNA translocation in skeletal muscle cells for gene therapy applications. 相似文献