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Graft Yield (graft + yield)
Selected AbstractsFascia Augmentation of the Vocal Fold: Graft Yield in the Canine and Preliminary Clinical Experience,THE LARYNGOSCOPE, Issue 5 2001Sanford G. Duke MD Abstract Introduction Glottal insufficiency resulting from vocal fold bowing, hypomobility, or scar is frequently treated by injection augmentation. Injection augmentation with fat, collagen, gel foam, polytef, and recently, fascia lata has been previously reported. Variable graft yield and poor host-tissue tolerance have motivated the continued search for an ideal graft substance. Study Design A prospective trial of autologous fascia augmentation of the vocal cord in the human and in an animal model. Methods Autologous fascia injection augmentation (AFIA) was evaluated in 8 canines and 40 patients at our institution between 1998 and 2000. The animal study compared graft yield from AFIA with autologous fat yield. The outcome measure was graft yield calculated from histological examination of larynges 12 weeks after injection augmentation. Clinical trial outcome measures included symptom surveys, acoustical voice analyses, and subjective voice assessments. Mean follow-up was 9 months. Results In the canine larynx, the mean graft yield for AFIA was 33% (range, 5%,84%) compared with autologous lipoinjection (47%; range, 7%,96%;P = .57). Subjective improvement in vocal quality was reported by 95% of patients (38 of 40) after AFIA. Preoperative and postoperative voice analysis data were obtained from 26 patients. Subjective voice rating demonstrated a significant improvement after AFIA (P <.0001). Acoustical parameters of jitter, shimmer, noise-to-harmonic ratio, phonatory range, and degree unvoiced improved significantly (P <.05) in all patients after fascia augmentation. Conclusions Based on the animal study, we concluded that graft yields are excellent but variable for AFIA. The result is similar in variability and overall yield to autologous lipoinjection. Subjective and objective analyses of voice outcomes after AFIA are universally improved. Fascia appears to be an excellent alternative to lipoinjection in properly selected cases of glottic insufficiency. [source] Functional finishing by using atmospheric pressure plasma: Grafting of PET nonwoven fabricJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Younsook Shin Abstract Poly (ethylene terephtalate) (PET) nonwoven fabric was treated with He/O2 plasma to produce peroxides and grafted with acrylic acid (AA) for introducing carboxyl groups onto PET surface. The graft yield increased with AA concentration from 1.5M to 2.5M, and then decreased with further increase in AA concentration. Graft yield increased with sodium pyrosulfite (SPS) concentration from 0.005M to 0.02M, and then decreased with further increase of SPS concentration. X-ray photoelectron spectroscopy results indicated that both of plasma treatment and AA grafting increased oxygen content and decreased carbon content on the PET nonwoven fabric surface. The grafted PET nonwoven fabric showed increase in moisture regain and dye uptake. And drastic increase in wettability was observed after grafting. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3655,3659, 2007 [source] Reactive grafting of glycidyl methacrylate onto polypropyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Emma-Louise Burton Abstract This work explored the melt-phase grafting of glycidyl methacrylate (GMA) onto polypropylene on a closely intermeshing corotating twin-screw extruder (16-mm screws, 40 : 1 length/diameter ratio). The modification of the base polypropylene to produce GMA-grafted polypropylene was achieved via peroxide-induced hydrogen abstraction from the polypropylene followed by the grafting of the GMA monomer or by the grafting of styrene followed by copolymerization with the GMA. In this study, both the position and order of the reactant addition were investigated as a route to improving graft yields and reducing side reactions (degradation). For the peroxide,GMA system, adding GMA to the melt before the peroxide resulted in significant improvements in the graft levels because of the improved dispersion of GMA in the melt. The addition of a comonomer (styrene) was explored as a second route to improving the graft yield. Although the addition of the comonomer led to a considerable rise in the level of grafted GMA, altering the order of the reactant addition was not found to contribute to an increase in the grafted GMA levels. However, variable levels of grafted styrene were achieved, and this may play an important role in the development of grafted polymers to suit specific needs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Induction of chemical and moisture resistance in Saccharum spontaneum L fiber through graft copolymerization with methyl methacrylate and study of morphological changesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Balbir Singh Kaith Abstract In this article, morphological modification of Saccharum spontaneum L, a natural fiber through graft copolymerization with methylmethacrylate using ferrous ammonium sulfate,potassium per sulfate redox initiator has been reported. Different reaction parameters such as reaction temperature, time, initiator molar ratio, monomer concentration, pH and solvent were optimized to get maximum graft yield (144%). The graft copolymers thus formed were characterized by Fourier transform infrared, scanning electron microscopy, X-ray diffraction and thermogravimetric, differential thermal analysis, and differential thermogravimetric techniques. Graft copolymer has been found to be more moisture resistant and also showed higher chemical and thermal resistance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Grafting of poly(N -isopropylacrylamide) onto nylon and polystyrene surfaces by atmospheric plasma treatment followed with free radical graft copolymerizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Xiaoling Wang Abstract Stimuli-responsive polymer materials (SRPs) have potential uses in drug delivery, tissue engineering, bioreactors, and cell-surface adhesion control. Temperature-responsive surfaces were fabricated by grafting poly(N -isopropylacrylamide) (PNIPAM) onto nylon and polystyrene surfaces via a new procedure, i.e., He atmospheric plasma treatment followed by free radical graft copolymerization. The atmospheric plasma exhibits the activation capability to initiate graft copolymerization. The procedure is suitable for integration into a continuous manufacturing process. To reduce homopolymerization and enhance graft yield, Mohr's salt was added. The graft of PNIPAM was confirmed by Fourier transform infrared spectroscopy and atomic force microscopy. Dramatic water contact angle increase was found for PNIPAM-grafted polymers at about 32°C, indicating the temperature sensitivity of the grafted surface, i.e., the change of surface from hydrophilic to hydrophobic when temperature increases above the lower critical solution temperature (LCST). The addition of Mohr's salt enhances the grafting reaction and the magnitude of temperature sensitivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3614,3621, 2007 [source] Morphology and mechanical properties of impact modified polypropylene blendsPOLYMER ENGINEERING & SCIENCE, Issue 11 2008Nathan Tortorella Isotactic polypropylene (PP) has been reactively blended with various grades of an ethylene,octene copolymer (EOC) in a twin-screw extruder. Free radical polymerization of styrene and a multifunctional acrylate during melt extrusion has resulted in an enhancement of mechanical properties over the binary blend. The reactive blend exhibits a notched Izod impact strength over 12 times that of pure polypropylene and greater than double the performance of the binary blend. Electron microscopy shows that by grafting onto the polymers, elastomer particle size and interparticle distance decrease, while particle shape becomes less spherical. The acrylate is crucial to achieve superior performance, as infrared spectra correlate an increase in graft yield to improvements in stress,strain behavior and impact strength. In addition, melt flow index (MFI) and melt strength data indicate a reduction in unwanted side reactions of polypropylene and the presence of long-chain branching. Dynamic-mechanical analysis reveals that the reaction promotes miscibility between polypropylene and the EOC and reduces molecular mobility at their glass-transition temperatures. Mechanical properties, graft yield, and MFI are shown to be highly dependent upon the elastomer's concentration, density, and molecular weight, initiator and monomer concentration, as well as processing temperature. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Gamma radiation induced graft copolymerization of acrylamide onto EPDM blended with PEPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2002E. M. El-Nesr Abstract Gamma radiation induced grafting of acrylamide (AAm) onto vulcanized strips of EPDM and EPDM/PE blends has been carried out. The effects of different parameters on the graft yield have been investigated. These parameters include: radiation dose, monomer concentration, diluent composition and types of inhibitors. It has been found that water is the most appropriate solvent. The preswelling of crosslinked rubber samples in cyclohexane prior to grafting enhances the grafting and the addition of methanol to water as binary diluent in the ratio (1,:,1) decreases the graft yield. The presence of Mohr's salt and copper sulfate in the reaction mixture in the molar ratio (2.1,:,0.5) markedly increases the graft yield. Evidence of grafting have been conducted using thermal analysis as well as swelling measurements in water. Also, it has been found that the mechanical properties of the blends decrease at graft yield 13%. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fascia Augmentation of the Vocal Fold: Graft Yield in the Canine and Preliminary Clinical Experience,THE LARYNGOSCOPE, Issue 5 2001Sanford G. Duke MD Abstract Introduction Glottal insufficiency resulting from vocal fold bowing, hypomobility, or scar is frequently treated by injection augmentation. Injection augmentation with fat, collagen, gel foam, polytef, and recently, fascia lata has been previously reported. Variable graft yield and poor host-tissue tolerance have motivated the continued search for an ideal graft substance. Study Design A prospective trial of autologous fascia augmentation of the vocal cord in the human and in an animal model. Methods Autologous fascia injection augmentation (AFIA) was evaluated in 8 canines and 40 patients at our institution between 1998 and 2000. The animal study compared graft yield from AFIA with autologous fat yield. The outcome measure was graft yield calculated from histological examination of larynges 12 weeks after injection augmentation. Clinical trial outcome measures included symptom surveys, acoustical voice analyses, and subjective voice assessments. Mean follow-up was 9 months. Results In the canine larynx, the mean graft yield for AFIA was 33% (range, 5%,84%) compared with autologous lipoinjection (47%; range, 7%,96%;P = .57). Subjective improvement in vocal quality was reported by 95% of patients (38 of 40) after AFIA. Preoperative and postoperative voice analysis data were obtained from 26 patients. Subjective voice rating demonstrated a significant improvement after AFIA (P <.0001). Acoustical parameters of jitter, shimmer, noise-to-harmonic ratio, phonatory range, and degree unvoiced improved significantly (P <.05) in all patients after fascia augmentation. Conclusions Based on the animal study, we concluded that graft yields are excellent but variable for AFIA. The result is similar in variability and overall yield to autologous lipoinjection. Subjective and objective analyses of voice outcomes after AFIA are universally improved. Fascia appears to be an excellent alternative to lipoinjection in properly selected cases of glottic insufficiency. [source] Reactive grafting of glycidyl methacrylate onto polypropyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Emma-Louise Burton Abstract This work explored the melt-phase grafting of glycidyl methacrylate (GMA) onto polypropylene on a closely intermeshing corotating twin-screw extruder (16-mm screws, 40 : 1 length/diameter ratio). The modification of the base polypropylene to produce GMA-grafted polypropylene was achieved via peroxide-induced hydrogen abstraction from the polypropylene followed by the grafting of the GMA monomer or by the grafting of styrene followed by copolymerization with the GMA. In this study, both the position and order of the reactant addition were investigated as a route to improving graft yields and reducing side reactions (degradation). For the peroxide,GMA system, adding GMA to the melt before the peroxide resulted in significant improvements in the graft levels because of the improved dispersion of GMA in the melt. The addition of a comonomer (styrene) was explored as a second route to improving the graft yield. Although the addition of the comonomer led to a considerable rise in the level of grafted GMA, altering the order of the reactant addition was not found to contribute to an increase in the grafted GMA levels. However, variable levels of grafted styrene were achieved, and this may play an important role in the development of grafted polymers to suit specific needs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] The transient nature of maximum maleic anhydride grafting of polypropylene: A mechanistic approach based on a consecutive reaction model.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Abstract This article compares the batch solution and molten state chemical modification of an atactic polypropylene to yield a grafted polypropylene. Short reaction times appear to be sufficient and indeed necessary for the highest graft yields to be obtained if degradative processes occurring in both reaction media are to be avoided. The consecutive reactions for the optimized grafting reaction pathway were proposed for the solution process in an earlier article. The present work attempts to correlate this pathway with that of the molten state process. Grafted succinic anhydride groups react with two resorcine molecules to yield grafted succinyl-fluorescein groups. This work considers the resorcine units as true molecular probes, to be able to stabilize and activate the complexes formed between the succinic anhydride groups and the propylene sequence. This work shows the unsteady and later dynamic character of the process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 345,351, 2007 [source] Thermoresponsive transport through porous membranes with grafted PNIPAM gatesAICHE JOURNAL, Issue 4 2003Liang-Yin Chu Both thermoresponsive flat membranes and core-shell microcapsule membranes, with a porous membrane substrate and grafted poly(N-isopropylacrylamide) (PNIPAM) gates, were successfully prepared using a plasma-graft pore-filling polymerization method. PNIPAM was proven to be grafted homogeneously onto the porous membrane substrates, in the direction of both the membrane thickness and surface. Regardless of the solute molecular size, temperature had an opposite effect on diffusion coefficients of the solute across the PNIPAM-grafted membranes with low graft yields as opposed to those with high graft yields. The PE-g-PNIPAM membranes change from positive thermo-response to negative thermoresponse types with increasing pore-filling ratios at around 30%. Phenomenological models were developed for predicting the diffusion coefficient of the solute across PNIPAM-grafted membranes at temperatures, both above and below the lower critical solution temperature (LCST). Predicted diffusional coefficients of solutes across both the PNIPAM-grafted flat and PNIPAM-grafted microcapsule membranes fit the experimental values. To obtain an ideal result for the diffusional thermoresponsive controlled release through PNIPAM-grafted membranes, the substrates strong enough to prevent any conformation changes are more suitable for preparing thermoresponsive membranes than weak ones. [source] Fascia Augmentation of the Vocal Fold: Graft Yield in the Canine and Preliminary Clinical Experience,THE LARYNGOSCOPE, Issue 5 2001Sanford G. Duke MD Abstract Introduction Glottal insufficiency resulting from vocal fold bowing, hypomobility, or scar is frequently treated by injection augmentation. Injection augmentation with fat, collagen, gel foam, polytef, and recently, fascia lata has been previously reported. Variable graft yield and poor host-tissue tolerance have motivated the continued search for an ideal graft substance. Study Design A prospective trial of autologous fascia augmentation of the vocal cord in the human and in an animal model. Methods Autologous fascia injection augmentation (AFIA) was evaluated in 8 canines and 40 patients at our institution between 1998 and 2000. The animal study compared graft yield from AFIA with autologous fat yield. The outcome measure was graft yield calculated from histological examination of larynges 12 weeks after injection augmentation. Clinical trial outcome measures included symptom surveys, acoustical voice analyses, and subjective voice assessments. Mean follow-up was 9 months. Results In the canine larynx, the mean graft yield for AFIA was 33% (range, 5%,84%) compared with autologous lipoinjection (47%; range, 7%,96%;P = .57). Subjective improvement in vocal quality was reported by 95% of patients (38 of 40) after AFIA. Preoperative and postoperative voice analysis data were obtained from 26 patients. Subjective voice rating demonstrated a significant improvement after AFIA (P <.0001). Acoustical parameters of jitter, shimmer, noise-to-harmonic ratio, phonatory range, and degree unvoiced improved significantly (P <.05) in all patients after fascia augmentation. Conclusions Based on the animal study, we concluded that graft yields are excellent but variable for AFIA. The result is similar in variability and overall yield to autologous lipoinjection. Subjective and objective analyses of voice outcomes after AFIA are universally improved. Fascia appears to be an excellent alternative to lipoinjection in properly selected cases of glottic insufficiency. [source] | ||||||||||