Search results for "Esters"
showing 10 items of 305 documents
Evaluation of mechanical and morphologic features of PLLA membranes as supports for perfusion cells culture systems
2015
Abstract Porous biodegradable PLLA membranes, which can be used as supports for perfusion cell culture systems were designed, developed and characterized. PLLA membranes were prepared via diffusion induced phase separation (DIPS). A glass slab was coated with a binary PLLA–dioxane solution (8 wt.% PLLA) via dip coating, then pool immersed in two subsequent coagulation baths, and finally dried in a humidity-controlled environment. Surface and mechanical properties were evaluated by measuring pore size, porosity via scanning electron microscopy, storage modulus, loss modulus and loss angle by using a dynamic mechanical analysis (DMA). Cell adhesion assays on different membrane surfaces were a…
Steady State Counterbalance Valve Modeling with the Influence of Synthetic Ester Oils Using CFD
2020
This study looks in details at the effects of synthetic esters being applied to a counterbalance valve from the perspective of a system engineer. There is limited literature on the subject of applied synthetic esters and as such limited unbiased sources for information. This creates reluctance against the use of these fluids in sectors and regions with no prior experience and knowledge of what to expect. This study expands the applied literature by investigating a commercially available valve using commercial oils, a basic synthetic ester, a fully saturated synthetic ester and a typical mineral oil type for benchmarking. The investigation is based on both computational fluid dynamics and ex…
Novel silver-based nanoclay as an antimicrobial in polylactic acid food packaging coatings.
2010
This paper presents a comprehensive performance study of polylactic acid (PLA) biocomposites, obtained by solvent casting, containing a novel silver-based antimicrobial layered silicate additive for use in active food packaging applications. The silver-based nanoclay showed strong antimicrobial activity against Gram-negative Salmonella spp. Despite the fact that no exfoliation of the silver-based nanoclay in PLA was observed, as suggested by transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) experiments, the additive dispersed nicely throughout the PLA matrix to a nanoscale, yielding nanobiocomposites. The films were highly transparent with enhanced water barrier …
Polycaprolactone/gelatin-based scaffolds with tailored performance: in vitro and in vivo validation
2019
Abstract Nanofibrous scaffolds composed of polycaprolactone (PCL) and gelatin (Ge) were obtained through a hydrolytic assisted electrospinning process. The PCL-to-Ge proportion (100/0 to 20/80), as well as the dissolution time (24, 48, 72, 96, 120 h) into a 1:1 formic/acetic acid solvent before electrospinning were modified to obtain the different samples. A strong influence of these factors on the physicochemical properties of the scaffolds was observed. Higher Ge percentage reduced crystallinity, allowed a uniform morphology and increased water contact angle. The increase in the dissolution time considerably reduced the molar mass and, subsequently, fibre diameter and crystallinity were a…
Incorporation of an antibiotic in poly(lactic acid) and polypropylene by melt processing
2016
Purpose In this work an antibiotic, ciprofloxacin (CFX), was incorporated into 2 different polymeric matrices, poly(lactic acid) (PLA) and polypropylene (PP), to provide them with antimicrobial properties. The influence of CFX content on release kinetics and on antimicrobial and mechanical properties was evaluated. Methods CFX was incorporated into both the polymers by melt mixing. Results The effect of CFX incorporation was found to strongly depend on which polymer matrix was used. In particular, the antimicrobial tests revealed that PLA samples containing CFX produced no inhibition zone and only a slight antibacterial activity was observed when the highest concentration of CFX was added t…
Eubacteria and archaea communities in seven mesophile anaerobic digester plants in Germany
2015
Background Only a fraction of the microbial species used for anaerobic digestion in biogas production plants are methanogenic archaea. We have analyzed the taxonomic profiles of eubacteria and archaea, a set of chemical key parameters, and biogas production in samples from nine production plants in seven facilities in Thuringia, Germany, including co-digesters, leach-bed, and sewage sludge treatment plants. Reactors were sampled twice, at a 1-week interval, and three biological replicates were taken in each case. Results A complex taxonomic composition was found for both eubacteria and archaea, both of which strongly correlated with digester type. Plant-degrading Firmicutes as well as Bacte…
Contribution of outgrowth endothelial cells from human peripheral blood on in vivo vascularization of bone tissue engineered constructs based on star…
2009
In the present study we assessed the potential of human outgrowth endothelial cells (OEC), a subpopulation within endothelial progenitor cell cultures, to support the vascularization of a complex tissue engineered construct for bone. OEC cultured on starch polycaprolactone fiber meshes (SPCL) in monoculture retained their endothelial functionality and responded to angiogenic stimulation by VEGF (vascular endothelial growth factor) in fibrin gel-assays in vitro. Co-culture of OEC with human primary osteoblasts (pOB) on SPCL, induced an angiogenic activation of OEC towards microvessel-like structures achieved without additional supplementation with angiogenic growth factors. Effects of co-cul…
An enantioselective synthesis of the C(33)–C(37) fragment of Amphotericin B
2003
An enantioselective synthesis of the C(33)–C(37) tripropionate fragment of Amphotericin B has been developed in only 6 steps. Peer reviewed
Hydrogen-bond-mediated self-assembly of 26-membered diaza tetraester crowns of 3,5-disubstituted 1 h -pyrazole. Dimerization study in the solid state…
2011
By using an improved synthetic method reported earlier, the cyclic stannoxanes obtained from RN-diethanolamine (R = Me, Bu) and dibutyltin oxide have been reacted with 1H-pyrazole-3,5-dicarbonyl dichloride to afford 26-membered diaza tetraester crowns (1, R = Me; 3, R = Bu) and 39-membered triaza hexaester crowns (2, R = Me; 4, R = Bu). The new structures were identified from their analytical and spectroscopic (1H and 13C NMR, FAB-MS, and/or ESI-MS) data. Both diaza tetraester crowns (1 and 3), containing two 1H-pyrazole units, self-assemble into dimeric species through the formation of four hydrogen bonds involving the two NH pyrazole groups and the two tertiary amine groups of both crowns…
Cationic Nanohydrogel Particles as Potential siRNA Carriers for Cellular Delivery
2012
Oligonucleotides such as short, double-stranded RNA (siRNA) or plasmid DNA (pDNA) promise high potential in gene therapy. For pharmaceutical application, however, adequate drug carriers are required. Among various concepts progressing in the market or final development, nanosized hydrogel particles may serve as novel transport media especially for siRNA. In this work, a new concept of synthesizing polymeric cationic nanohydrogels was developed, which offers a promising strategy to complex and transport siRNA into cells. For this purpose, amphiphilic reactive ester block copolymers were synthesized by RAFT polymerization of pentafluorophenyl methacrylate as reactive ester monomer together wi…