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101.
102.
Semi-interpenetrating networks (sIPNs) designed to mimic extracellular matrix via covalent crosslinking of poly(ethylene glycol)
diacrylate in the presence of gelatin have been shown to aid in wound healing, particularly when loaded with soluble factors.
Ideal systems for tissue repair permit an effective release of therapeutic agents and flow of nutrients to proliferating cells.
Appropriate network characterization can, consequently, be used to convey an understanding of the mass transfer kinetics necessary
for materials to aid in the wound healing process. Solute transport from and through sIPNs has not yet been thoroughly evaluated.
In the current study, the diffusivity of growth factors and nutrients through the polymeric system was determined. Transport
of keratinocyte growth factor was modeled by treating the sIPN as a plane sheet into which the protein was loaded. The diffusion
coefficient was determined to be 4.86 × 10−9 ± 1.86 × 10−12 cm2/s. Glucose transport was modeled as flow through a semi-permeable membrane. Using lag-time analysis, the diffusion coefficient
was calculated to be 2.25 × 10−6 ± 1.98 × 10−7 cm2/s. The results were evaluated in conjunction with previous studies on controlled drug release from sIPNs. As expected from
Einstein-Stokes equation, diffusivity decreased as molecular size increased. The results offer insight into the structure-function
design paradigm and show that release from the polymeric system is diffusion controlled, rather than dissolution controlled. 相似文献
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Becoming a better designer means getting better at what we do now while not getting lulled into accepting the status quo. To stay effective as designers, we need to continue to learn, adapt, keep an open mind, and work to perfect our craft. 相似文献
106.
J. Jedlinski J.‐L. Grosseau‐Poussard G. Bonnet K. Kowalski A. Bernasik G. Smola M. Nocun 《工业材料与腐蚀》2011,62(6):490-495
Early oxidation of unmodified and yttrium‐implanted or chromium‐implanted β‐NiAl intermetallic compound at 1473 K was studied using a combination of two‐stage‐oxidation exposure with 18O2 as a tracer, SIMS elemental distribution analysis (depth profiling and imaging modes) and photoluminescence spectroscopy analysis of the scale phase composition. It was found that phase transformation of transient aluminium oxides, represented by θ‐ Al2O3 into stable and protective α‐Al2O3 occurs locally and is affected by implanted additions: Yttrium retarded while chromium appeared to accelerate it. Typical patch‐ and/or web‐like scale morphology of the growing scales was observed. 相似文献
107.
Rebecca L. H. Chiu 《Urban Policy and Research》2013,31(4):455-468
Abstract Marketisation and privatization reforms implemented in Shanghai since 1980 have facilitated housing construction and the improvement of housing conditions. The multiplication of construction capital would have been impossible without an effective implementation of the consumption reforms and general improvements in the economy. 相似文献
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The diffusive properties of two coextruded geomembranes, one with a polyamide inner core and the other with an ethylene vinyl-alcohol (EVOH) inner core, and a standard 0.53-mm (20-mil) linear low-density polyethylene (LLDPE) geomembrane were examined. Diffusion and sorption laboratory tests were performed to estimate the parameters controlling diffusive migration, including the partitioning, diffusion, and permeation coefficients of the geomembrane in both the aqueous and vapor phases. Results indicate a significant reduction in mass flux through the coextruded geomembranes compared to conventional LLDPE. The EVOH coextruded geomembrane had the lowest permeation coefficients (Pg) with a range of (2–6)×10?12?m2?s?1 for diffusion from the aqueous phase. These values for EVOH are upper bounds and the actual values may be lower than as stated. The polyamide (nylon) coextruded geomembrane had higher values than for EVOH, with a Pg range of (0.7–2.2)×10?11?m2?s?1 from the aqueous phase. The highest permeation coefficients were for the standard 20-mil LLDPE, which ranged from (0.6–1.1)×10?10?m2?s?1. Thus the permeation coefficient for LLDPE was about one order of magnitude greater than for the nylon coextruded and at least two orders of magnitudes higher than for the EVOH coextruded geomembrane. Both coextruded geomembranes showed decreased Pg values and therefore improved diffusive resistance to volatile organic compounds over traditional 0.56-mm PVC geomembranes. The EVOH geomembrane showed a 5–12-fold decrease in Pg in comparison to a 2.0-mm high density polyethylene geomembrane. 相似文献
110.
The effectiveness of a StormTreat system in treating stormwater from a commercial parking lot in Connecticut was evaluated. Flow-weighted composite samples were collected from StormTreat inflow and outflow during a 2-yr study. Bypass flow was not monitored. The StormTreat significantly (P < 0.05) reduced total suspended solids, total phosphorus, total Kjeldahl-N, total zinc, total copper, and fecal coliform bacteria on a concentration basis. The StormTreat system retained 49% total suspended solids, 74% total phosphorus, 44% total Kjeldahl-N, 45% total zinc, 29% total copper, 2% total lead on a mass basis, and 99% fecal coliform on a concentration basis. Treatment efficiency was not associated with storm size, chamber stage, discharge rate, or hydraulic retention time (r < 0.355). The system retained ammonia-N more efficiently during the summer than during the winter (P < 0.01) and retained total zinc less efficiently during the summer than during the winter (P < 0.05). Season did not significantly (P > 0.05) affect the treatment of other monitored water quality variables. The StormTreat system reduced the concentrations of stormwater pollutants commonly found in parking lot runoff. 相似文献