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Sample records for cabrol composite graft

  1. Cabrol-Type Aortocoronary Anastomosis Technique in Coronary Artery Bypass Surgery.

    Science.gov (United States)

    Kim, Tae Sik; Na, Chan-Young; An, Hyonggin

    2016-04-01

    Background In conventional coronary artery bypass grafting (CABG), multiple anastomoses in the ascending aorta are needed for multiple coronary targeting. We have introduced a single-site proximal anastomosis technique for multiple coronary targeting. A single anastomosis between the ascending aorta and graft was performed using a side-to-side maneuver (Cabrol type). Additionally, the graft was connected to another graft by end-to-end anastomosis for the coronary artery on the opposite side. We evaluated the long-term clinical outcome and graft patency of this Cabrol-type aortocoronary anastomosis technique. Methods From 2002 to 2012, a total of 483 patients (mean age, 64.6 years) underwent CABG using our Cabrol-type aortocoronary anastomosis technique. The average number of target coronary arteries per person was 3.4 ± 0.6. The mean follow-up duration was 74.2 ± 31.3 months; 98.7% of hospital survivors completed the follow-up. Postoperative coronary computed tomography angiography was performed in 377 patients (81.8%). Results Operative mortality was 4.6%. The actuarial overall survival rates at 1, 5, and 10 years were 97.8 ± 0.7%, 89.3 ± 1.5%, and 69.0 ± 3.9%, respectively. The actuarial major adverse cardiac and cerebrovascular event-free survival rates at 1, 5, and 10 years were 95.7 ± 0.9%, 80.1 ± 2.0%, and 60.8 ± 3.7%, respectively. One- and 5-year patency rates of the Cabrol-type aortocoronary graft were 81.1 ± 2.2% and 61.3 ± 3.6%, respectively. Conclusion Our Cabrol-type aortocoronary anastomosis technique did not have superior clinical outcomes and graft patency compared with conventional CABG. However, this technique might be an alternative option in select patients with atherosclerotic disease of the ascending aorta, or other embarrassing situations. PMID:26090886

  2. Can We Add Auricular Composite Graft to Our Rhinoplasty Armamentarium?

    OpenAIRE

    Manafi, Ali; Eslami Shahr Babaki, Amir; Mehrabani, Golnoush; Shahlaee, Abtine; Manafi, Amir

    2013-01-01

    BACKGROUND The ala of the nose, with its particular texture and characteristics, poses both aesthetically and functionally intriguing challenges and is rather problematic regarding choices for reconstructive methods. Both flaps and grafts have been used to restore natural structure of nasal ala. The present study summarizes a ten-year experience of reconstructive surgery using small composite grafts from non-cartilage bearing tissues, and large composite grafts, containing cartilaginous tissu...

  3. Vancomycin graft composite for infected bone defects

    International Nuclear Information System (INIS)

    Reconstructive surgery under septic conditions represents a major challenge in orthopaedics. Local application of antibiotics can provide high drug levels at the site of infection without systemic effects. However, removal of non-resorbable implants and filling of defects usually requires additional operative procedures. An ideal antibiotic carrier should provide for : 1) Effective bactericidal activity, especially against staphylococci including MRSA; 2) High and long lasting levels at the site of infection without local or systemic toxicity; 3) Repair of defects without a second stage procedure. Allogeneic cancellous bone is proven to be effective in restoration of bone stock. Vancomycin is effective against all gram-positive populations and the agent of choice for infections with MRSA. The aim of our study is to investigate the efficacy of a combination of both components in bone infection. Cancellous bone of human origin was processed during several steps and incubated in 10% vancomycin solution. The antimicrobial activity of the vancomycin graft composite (VGC) was evaluated using an agar diffusion bioassay against staphylococcus aureus and high performance liquid chromatography (HPLC). The testing period was up to 9 weeks. Elution of vancomycin from the graft was evaluated in 2.5% human albumin solution, which was exchanged every 24 hours. Concentration of vancomycin in allograft-bone was between 6.653[tg/g and 23.194gg/g with an average of 15.250 [tg/g, which is equivalent to 10.000 times the minimum inhibitory concentration (MIC) for s. aureus. The initial activity decreased to approx. 50% during the first week and approx. 30% at the end of the 9th week. The lowest values measured exceeded the MIC by 2000 times. Concentration in surrounding fluid decreased from 24.395,80 to 18,43pg/ml after 11 complete exchanges. Human cancellous bone, processed in an adequate way, offers capability to store high quantities of vancomycin. Vancomycin graft composites are

  4. Analysis of cartilage-polydioxanone foil composite grafts.

    Science.gov (United States)

    Kim, James H; Wong, Brian

    2013-12-01

    This study presents an analytical investigation into the mechanical behavior of a cartilage-polydioxanone (PDS) plate composite grafts. Numerical methods are used to provide a first-order, numerical model of the flexural stiffness of a cartilage-PDS graft. Flexural stiffness is a measure of resistance to bending and is inversely related to the amount of deformation a structure may experience when subjected to bending forces. The cartilage-PDS graft was modeled as a single composite beam. Using Bernoulli-Euler beam theory, a closed form equation for the theoretical flexural stiffness of the composite graft was developed. A parametric analysis was performed to see how the flexural properties of the composite model changed with varying thicknesses of PDS foil. The stiffness of the cartilage-PDS composite using 0.15-mm-thick PDS was four times higher than cartilage alone. The composite with a 0.5-mm-thick PDS graft was only 1.7 times stiffer than the composite with the 0.15-mm-thick PDS graft. Although a thicker graft material will yield higher flexural stiffness for the composite, the relationship between composite stiffness and PDS thickness is nonlinear. After a critical point, increments in graft thickness produce gradually smaller improvements in flexural stiffness. The small increase in stiffness when using the thicker PDS foils versus the 0.15 mm PDS foil may not be worth the potential complications (prolonged foreign body reaction, reduction in nutrient diffusion to cartilage) of using thicker artificial grafts. PMID:24327249

  5. Composite vascular repair grafts via micro-imprinting and electrospinning

    Science.gov (United States)

    Liu, Yuanyuan; Xiang, Ke; Chen, Haiping; Li, Yu; Hu, Qingxi

    2015-04-01

    Composite vascular grafts formed by micro-imprinting and electrospinning exhibited improved mechanical properties relative to those formed by electrospinning alone. The three-layered composite grafts mimic the three-layered structure of natural blood vessels. The middle layer is made by micro-imprinting poly-p-dioxanone (PPDO), while the inner and outer layers are electrospun mixtures of chitosan and polyvinyl alcohol. The graft morphology is characterized with scanning electron microscopy. For constant graft thicknesses, the PPDO increases the mechanical strength. Cells cultivated on the vascular grafts adhere and proliferate better because of the natural, biological chitosan in the inner and outer layers. Overall, the composite scaffolds could be good candidates for blood vessel repair.

  6. Composite vascular repair grafts via micro-imprinting and electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuanyuan, E-mail: yuanyuan-liu@shu.edu.cn; Hu, Qingxi, E-mail: huqingxi@shu.edu.cn [Rapid Manufacturing Engineering Center, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of Intelligent Manufacturing and Robotics, Shanghai 200072 (China); Xiang, Ke, E-mail: xiangke@shu.edu.cn; Chen, Haiping, E-mail: 519673062@qq.com; Li, Yu, E-mail: liyu@hpu.edu.cn [Rapid Manufacturing Engineering Center, Shanghai University, Shanghai 200444 (China)

    2015-04-15

    Composite vascular grafts formed by micro-imprinting and electrospinning exhibited improved mechanical properties relative to those formed by electrospinning alone. The three-layered composite grafts mimic the three-layered structure of natural blood vessels. The middle layer is made by micro-imprinting poly-p-dioxanone (PPDO), while the inner and outer layers are electrospun mixtures of chitosan and polyvinyl alcohol. The graft morphology is characterized with scanning electron microscopy. For constant graft thicknesses, the PPDO increases the mechanical strength. Cells cultivated on the vascular grafts adhere and proliferate better because of the natural, biological chitosan in the inner and outer layers. Overall, the composite scaffolds could be good candidates for blood vessel repair.

  7. Free Auricular Composite Graft for Acquired Nasal Stenosis

    Science.gov (United States)

    Riley, Charles A.; Lawlor, Claire M.; Gray, Mingyang Liu; Graham, H. Devon

    2016-01-01

    Background: Acquired nasal stenosis poses a reconstructive challenge for the facial plastic surgeon. Many surgical options are available, ranging from primary closure to skin grafts to free flap reconstruction for complex defects. The free auricular composite graft is a single-stage procedure that can be used to repair nasal vestibular stenosis causing nasal obstruction. Case Report: We present the case of a patient with acquired nasal stenosis as a result of prolonged nasal tampon placement secondary to severe epistaxis and subsequent nasal vestibular infection. Repair via auricular composite graft was successful, and we provide a thorough explanation of graft design and operative technique. Conclusion: Free auricular composite grafts can produce desirable functional and aesthetic outcomes and should be considered in patients presenting with acquired nasal stenosis. PMID:27303225

  8. Technical modification for composite grafts in myocardial revascularization surgery

    Directory of Open Access Journals (Sweden)

    Chaccur Paulo

    2002-01-01

    Full Text Available OBJECTIVE: In the last decade, the coronary artery bypass grafts (CABG with arterial grafting had been remarkable, mainly the combined ones in Y or T form, which start from the left internal thoracic artery (LITA. Elaborating this kind of grafting, we identified a certain worry related to the anastomoses of the radial artery in LITA, principally when realized in T, since any small traction, angulations or spasms of the radial artery might impaired the flow of the distal anastomoses of LITA to the anterior interventricular artery. METHOD: We modified the combined graft technique, by making anastomoses of the radial artery to the anterior interventricular artery, and, consequently the LITA is sewed above the anastomoses of the radial artery to the anterior interventricular artery, favoring therefore, the revascularization of the anterior interventricular artery with the LITA, transforming the radial artery into almost an extension of the LITA to the remaining branches of the left coronary artery. CONCLUSIONS: This technical modification for these composite grafts is simple, safer and effective, and it will enable a larger number of surgeons to routinelyuse composite grafts in coronary artery bypass grafting.

  9. Composites with polymer-grafted carbon nanotubes

    OpenAIRE

    Paiva, M. C.; Novais, R. M.; Covas, J. A.

    2014-01-01

    Carbon nanotube (CNT)/polymer composites exhibit the processability advantages of plastics, while conveying electrical conductivity characteristics suitable for electric transport, or for sensing functionalities. The success of their application depends on the ability to homogeneously disperse the CNT in the polymer matrices to form a stable conductive network. The structural strength of the nanocomposite is also desirable, and may be a requirement. The chemical functionalization of the CNT i...

  10. Application of Normobaric Hyperoxygenation to an Ischemic Flap and a Composite Skin Graft

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    Jun Araki

    2014-05-01

    Conclusions: The composite graft was maintained until revascularization by plasmatic diffusion from surrounding tissues, in which PtO2 was improved by NBO. NBO may be an effective adjunct therapy that can be performed readily after nonvascularized tissue grafting.

  11. Silicon tetrachloride plasma induced grafting for starch-based composites

    Science.gov (United States)

    Ma, Yonghui C.

    Non-modified virgin starch is seldom used directly in industrial applications. Instead, it is often physically and/or chemically modified to achieve certain enhanced properties. For many of the non-food applications, these modifications involve changing its hydrophilicity to create hydrophobic starch. In this study, the hydrophobic starch was produced through silicon tetrachloride (SiCl4) plasma induced graft polymerization, so that it could be used as a renewable and biodegradable component of, or substitute for, the petrochemical-based plastics. It was suggested that this starch graft-copolymer might be used as reinforcing components in silicone-rubber materials for starch-based composites. To make this starch graft-copolymer, the ethyl ether-extracted starch powders were surface functionalized by SiCl4 plasma using a 13.56 MHz radio frequency rotating plasma reactor and subsequently stabilized by either ethylene diamine or dichlorodimethylsilane (DCDMS). The functionalized starch was then graft-polymerized with DCDMS to form polydimethylsiloxane (PDMS) layers around the starch granules. The presence of this PDMS layer was demonstrated by electron spectroscopy for chemical analysis (ESCA/XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), gas chromatography-mass spectroscopy (GC-MS), thermo gravimetry/differential thermal analysis (TG/DTA), and other analyses. It was shown that the surface morphology, thermal properties, swelling characteristic, and hydrophilicity of starch were all changed due to the existence of this protective hydrophobic PDMS layer. Several different procedures to carry out the functionalization and graft polymerization steps were evaluated to improve the effectiveness of the reactions and to prevent the samples from being hydrolyzed by the grafting byproduct HCl. Actinometry, GC-MS, and residual gas analyzer (RGA) were used to investigate the mechanisms of the SiCl4 discharge and to optimize the plasma

  12. Eyebrow reconstruction using composite graft and microsurgical transplant.

    Science.gov (United States)

    Vachiramon, A; Aghabeigi, B; Crean, St-John

    2004-07-01

    The pivotal role that eyebrows play in facial expression and aesthetics is widely accepted, along with the difficulties faced by surgeons in reconstructing defects in this area. The case study presented demonstrates reconstruction of a traumatic eyebrow defect using a post-auricular composite graft in combination with a microfollicular hair transplant technique. The advantage of the combined approach is discussed with reference to the fine tuning of the adjoining areas between reconstructed and undamaged hair-bearing regions. The advantages of this technique in control of the direction of hair growth and preservation of hair density are emphasised. PMID:15183417

  13. POTENTIAL USE OF GRAFT COPOLYMERS OF MERCERIZED FLAX AS FILLER IN POLYSTYRENE COMPOSITE MATERIALS

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    Susheel Kalia

    2008-11-01

    Full Text Available Graft copolymerization of binary vinyl monomers onto mercerized flax fiber was carried out for the enhancement of mechanical properties of polystyrene composites. Binary vinyl monomer mixture of AA+AN has been found to show maximum grafting (33.55% onto mercerized flax. Graft copolymers thus synthesized were characterized with FT-IR spectroscopy, SEM, and TGA techniques. Mercerized flax (MF showed maximum thermal stability in comparison to graft copolymers. It has been found that polystyrene composites reinforced with graft copolymers showed improvement in mechanical properties such as wear resistance, compressive strength, and tensile strength.

  14. Grafting

    International Nuclear Information System (INIS)

    The unique value of ionizing radiation for the initiation of grafting to backbone polymers is discussed. The principles of the technique are briefly reviewed. The conditions under which free radicals and ions participate in these reactions are examined. Examples of representative grafting processes are considered to illustrate where the technique can be of potential commercial value to a wide range of industries. The general principles of these grafting reactions are shown to be applicable to radiation induced rapid cure technology such as is provided by electron beam processing facilities. Grafting reactions initiated by UV are also treated and shown to be of importance because of the many similarities in properties of the ionizing radiation and UV systems, also the rapid industrial exploitation of EB and sensitized UV processing technology. Possible future trends in radiation grafting are outlined. (author)

  15. Tomato salt tolerance: Impact of grafting and water composition on yield and ion relations

    Science.gov (United States)

    We evaluated the salt tolerance of tomato cv Big Dena under both non-grafted 2 conditions and when grafted on Maxifort rootstock, under a series of 5 salinity levels and two irrigation water composition types. The salinity levels of the irrigation water were -0.03, -0.15, -0.30, -0.45, and -0.60 MPa...

  16. Preparation and Crystallization of Carbon Nanotube/maleic Anhydride-grafted Polypropylene Composites

    Institute of Scientific and Technical Information of China (English)

    Xiaohua CHEN; Jing HU; Lingping ZHOU; Wenhua LI; Zi YANG; Yanguo WANG

    2008-01-01

    Carbon nanotube (CNT)/maleic acid anhydride (MAH)-grafted polypropylene (PP) composites were prepared by in situ grafting method. Infrared spectroscopy showed that the CNTs were linked to PP by MAH grafting. The microstructures and calorimetry analysis indicated that the crystallization behaviors of the filled and unfilled PP were quite different. The addition of CNTs dramatically reduced the spherulite size, increased crystallization rate and improved the thermal stability of PP. These results confirmed the expected nucleant effect of CNT on the crystallization of PP. Scanning and transmission electron microscopy showed that the CNTs were dispersed homogeneously, indicating that the original CNT bundles were separated into individual tubes by the grafting.

  17. Osteogenetic activity in composite grafts of demineralized compact bone and marrow

    International Nuclear Information System (INIS)

    The effects of a composite graft of autologous marrow and demineralized autologous compact bone on the healing of a surgically created bone defect were observed in adult rabbits. A segment of the radius was bilaterally resected, demineralized, and replaced. On one side the bone graft was supplemented with autologous marrow. The new bone formation was measured 14 and 28 days after operation by roentgenography, including planimetry with scintigraphy and autoradiography using /sup 99m/Tc-labelled MDP. The composite graft, i.e., demineralized compact bone and marrow, had a significantly higher (p less than 0.01) bone formation rate 14 days after operation compared with the graft with demineralized compact bone in the opposite radius. At 28 days, however, there were no differences between the sides. Viable autologous marrow cells and demineralized autologous compact bone graft accelerate the rate of osteogenesis, but only at the beginning of the healing process

  18. Preparation and characterization of a novel bone graft composite containing bone ash and egg shell powder

    Indian Academy of Sciences (India)

    Gunasekaran Krithiga; Thotapalli P Sastry

    2011-02-01

    Egg shells which were hitherto discarded as wastes were collected, purified and powdered into a particle size in the range of 5–50 m. A composite bone graft material in cylindrical form was prepared using egg shell powder (ESP), bone ash (BA) and gelatin. These bone grafts were characterized for their FT–IR, TGA, XRD, SEM and mechanical properties. The mechanical studies indicate that the composite having a stoichiometric ratio of BA (3 g) and ESP (7 g) has shown better mechanical properties. X-ray diffraction (XRD) data indicated the crystallographic nature of BA is akin to hydroxyapatite (HA) and both BA and ESP did not lose their crystalline nature when bone grafts were prepared. This revealed that ESP may be used as a component in bone graft utilizing the solid waste from the poultry industry.

  19. Experimental posterolateral spinal fusion with beta tricalcium phosphate ceramic and bone marrow aspirate composite graft

    OpenAIRE

    Gupta Ankit; Chauhan Vijendra; Chauhan Neena; Sharma Sansar; Maheshwari Rajesh; Agarwal Atul

    2010-01-01

    Background: Beta tricalcium phosphate is commonly used in metaphyseal defects but its use in posterolateral spinal fusion remains controversial. There are very few published animal studies in which use of beta tricalcium phosphate has been evaluated in the posterolateral lumbar arthrodesis model. Hence we conducted a study to evaluate the potential of composite graft of beta tricalcium phosphate and bone marrow aspirate in comparison to autologous bone graft, when used for posterolateral spin...

  20. Interface property improvement of the composite reinforced by radiation grafted carbon fibers

    International Nuclear Information System (INIS)

    Radiation processing is a high efficient, energy-saving and environment-friendly technology, and has been widely used to modify material interfaces. In this paper, simultaneous γ-ray radiation graft copolymerization was used to improve surface property of carbon fibers (CF) with phenolic aldehyde/ethyl alcohol solutions of different concentrations. The CF samples treated with the solutions were irradiated by 60Co γ-rays to 30 kGy at a dose rate of 4.8 kGy/h. The grafted samples were characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). And interlaminar shear strength (ILSS) of the composite reinforced by the grafted CFs was compared to the control (composites reinforced by the virgin CFs). The AFM measurement revealed obvious morphology changes of the grafted CF. The XPS spectra showed that the oxygen/carbon ratio and quantity of oxygen functional groups were enhanced efficiently by the radiation graft copolymerization. And interfacial performance of the composite reinforced by the grafted CFs was enhanced significantly. (authors)

  1. Reinforcing polymer composites with epoxide-grafted carbon nanotubes

    International Nuclear Information System (INIS)

    An in situ functionalization method was used to graft epoxide onto single-walled carbon nanotubes (SWNTs) and improve the integration of SWNTs into epoxy polymer. The characterization results of Raman, FT-IR and transmission electron microscopy (TEM) validated the successful functionalization with epoxide. These functionalized SWNTs were used to fabricate nanocomposites, resulting in uniform dispersion and strong interfacial bonding. The mechanical test demonstrated that, with only 1 wt% loading of functionalized SWNTs, the tensile strength of nanocomposites was improved by 40%, and Young's modulus by 60%.These results suggested that efficient load transfer has been achieved through epoxide-grafting. This investigation provided an efficient way to improve the interfacial bonding of multifunctional high-performance nanocomposites for lightweight structure material applications

  2. Composite coating of 58S bioglass and hydroxyapatite on a poly (ethylene terepthalate) artificial ligament graft for the graft osseointegration in a bone tunnel

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the effect of the combination of hydroxyapatite (HA) and bioglass (BG) on polyethylene terephthalate (PET) artificial ligament graft osseointegration within the bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells proved that this HA/BG composite coating can promote the cell compatibility of grafts. A rabbit extraarticular tendon-to-bone healing model was used to evaluate the effect of this composite coating on PET artificial ligaments in vivo. The final results demonstrated that HA/BG coating improved new bone formation at the graft-bone interface and increased the load-to-failure property of graft in bone tunnel compared to the control group at early time. The study has shown that HA/BG composite coating on the PET artificial ligament surface has a positive effect in the induction of artificial ligament osseointegration within the bone tunnel.

  3. Thermal and dynamic mechanical properties of grafted kenaf filled poly (vinyl chloride)/ethylene vinyl acetate composites

    International Nuclear Information System (INIS)

    Highlights: • Study on thermal and dynamic mechanical properties of PVC/EVA/PMMA grafted kenaf fiber. • PMMA grafted kenaf fiber showed good interaction with PVC/EVA blends. • Thermal stability of the composites increase upon PMMA grafting on kenaf fiber. • The crystallinity of the composites decrease upon PMMA grafting on kenaf fiber. • PMMA grafted fiber provides more reinforcement on PVC/EVA/grafted PMMA composite. - Abstract: The effects of kenaf and poly (methyl methacrylate grafted kenaf on the thermal and dynamic mechanical properties of poly (vinyl chloride), PVC and ethylene vinyl acetate, EVA blends were investigated. The PVC/EVA/kenaf composites were prepared by mixing the grafted and ungrafted kenaf fiber and PVC/EVA blend using HAAKE Rheomixer at a temperature of 150 °C and the rotor speed at 50 rpm for 20 min. The composites were subjected to Differential Scanning Calorimetric (DSC), Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and Scanning Electron Microscopy (SEM) studies. The DSC data revealed that the crystallinity of the EVA decreased with the addition of 30% grafted and ungrafted kenaf fibers. TGA and derivative thermogravimetric (DTG) curves displayed an increase in the thermal stability of the composites upon grafting of the fiber. Studies on DMA indicate that the Tg of the PVC and EVA in the PVC/EVA/kenaf composites has been shifted to higher temperature with the addition of the kenaf fiber. The presence of PMMA on the surface of grafted kenaf fiber was further confirmed by the analytical results from FTIR. The morphology of fractured surfaces of the composites, which was examined by a scanning electron microscope, showed the adhesion between the kenaf fiber and the PVC/EVA matrix was improved upon grafting of the kenaf fiber

  4. Fabrication of engineered heart tissue grafts from alginate/collagen barium composite microbeads

    International Nuclear Information System (INIS)

    Cardiac tissue engineering holds great promise for the treatment of myocardial infarction. However, insufficient cell migration into the scaffolds used and inflammatory reactions due to scaffold biodegradation remain as issues to be addressed. Engineered heart tissue (EHT) grafts fabricated by means of a cell encapsulation technique provide cells with a tissue-like environment, thereby potentially enhancing cellular processes such as migration, proliferation, and differentiation, and tissue regeneration. This paper presents a study on the fabrication and characterization of EHT grafts from novel alginate/collagen composite microbeads by means of cell encapsulation. Specifically, the microbeads were fabricated from alginate and collagen by barium ion cross-linking, with neonatal rat cardiomyocytes encapsulated in the composite microbeads during the fabrication of the EHT grafts. To evaluate the suitablity of these EHT grafts for heart muscle repair, the growth of cardiac cells in the microbeads was examined by means of confocal microscopy and staining with DAPI and F-actin. The EHT grafts were analyzed by scanning electron microscopy and transmission electron microscopy, and the contractile function of the EHT grafts monitored using a digital video camera at different time points. The results show the proliferation of cardiac cells in the microbeads and formation of interconnected multilayer heart-like tissues, the presence of well-organized and dense cell structures, the presence of intercalated discs and spaced Z lines, and the spontaneous synchronized contractility of EHT grafts (at a rate of 20-30 beats min-1 after two weeks in culture). Taken together, these observations demonstrate that the novel alginate/collagen composite microbeads can provide a tissue-like microenvironment for cardiomyocytes that is suitable for fabricating native heart-like tissues.

  5. Fabrication of engineered heart tissue grafts from alginate/collagen barium composite microbeads

    Energy Technology Data Exchange (ETDEWEB)

    Bai, X P; Zheng, H X; Fang, R; Wang, T R; Li, Y; Tian, W M [Department of Life Science and Engineering, Harbin Institute of Technology, Harbin, 150080 (China); Hou, X L [The Fourth Affiliated Hospital of Harbin Medical University, Harbin, 150001 (China); Chen, X B, E-mail: tianweiming@gmail.com [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon (Canada)

    2011-08-15

    Cardiac tissue engineering holds great promise for the treatment of myocardial infarction. However, insufficient cell migration into the scaffolds used and inflammatory reactions due to scaffold biodegradation remain as issues to be addressed. Engineered heart tissue (EHT) grafts fabricated by means of a cell encapsulation technique provide cells with a tissue-like environment, thereby potentially enhancing cellular processes such as migration, proliferation, and differentiation, and tissue regeneration. This paper presents a study on the fabrication and characterization of EHT grafts from novel alginate/collagen composite microbeads by means of cell encapsulation. Specifically, the microbeads were fabricated from alginate and collagen by barium ion cross-linking, with neonatal rat cardiomyocytes encapsulated in the composite microbeads during the fabrication of the EHT grafts. To evaluate the suitablity of these EHT grafts for heart muscle repair, the growth of cardiac cells in the microbeads was examined by means of confocal microscopy and staining with DAPI and F-actin. The EHT grafts were analyzed by scanning electron microscopy and transmission electron microscopy, and the contractile function of the EHT grafts monitored using a digital video camera at different time points. The results show the proliferation of cardiac cells in the microbeads and formation of interconnected multilayer heart-like tissues, the presence of well-organized and dense cell structures, the presence of intercalated discs and spaced Z lines, and the spontaneous synchronized contractility of EHT grafts (at a rate of 20-30 beats min{sup -1} after two weeks in culture). Taken together, these observations demonstrate that the novel alginate/collagen composite microbeads can provide a tissue-like microenvironment for cardiomyocytes that is suitable for fabricating native heart-like tissues.

  6. Dehiscence of a Composite Aortic Graft and Pseudoan- eursym Late After a Bentall Operation

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    Hasan Alper-Gurbuz

    2015-10-01

    Full Text Available A 32-year-old female patient with previous Bentall operation and mitral valve repair surgery due to severe aortic insufficiency, mitral valve insufficiency, and ascending aortic aneurysm was admitted to our hospital with serious dyspnea, fatigue, and mild chest pain. Two-dimensional echocardiography demonstrated a markedly dilated basal aorta and cardiac chambers. Thoracic computed tomography scan highlighted a pseudoaneurysm, 14.5 cm in diameter (Figure 1. Urgent surgery was planned. The operation was performed under deep hypothermic cardiopulmonary bypass (arterial and venous line in the right femoral artery and vein. A large aortic pseudoaneurysm was demonstrated arising from the dehiscence of the proximal graft anastomosis (Figure 2. The composite graft did not require replacement, and it was possible to simply re-suture the composite graft and directly close the tear. The postoperative course was uneventful with no further evidence of leak from the anastomotic sites.

  7. Composites from maleated polyolefin-grafted wood particles produced via reactive extrusion

    Science.gov (United States)

    Carlborn, Karana

    This study examined the concept of using a reactive extrusion process to develop a new, formaldehyde-free binding system for wood composite products. The surfaces of wood particles were modified by grafting maleated polyethylene (MAPE) and maleated polypropylene (MAPP) compounds through a continuous reactive extrusion process. MAPE content was varied to study the effect of material composition on grafting efficiency, while extruder barrel temperatures and rotational screw speeds were varied to evaluate the effects of processing conditions on the modification of wood particles. Polymer molecular weight effects were followed using MAPP with different molecular weights. Efficiency of the modification was assessed using FTIR. 13C NMR and XPS surface analysis techniques, along with a titrimetric analysis to verify the esterification reaction between the wood particles and maleated polyolefins. Composite panels were made from wood particles modified with MAPE and MAPP binding agents under two different manufacturing methods. Specific contrasts of (i) base resin type, PE vs. PP, (ii) molecular weight/maleic anhydride content in MAPP binding agents, and (iii) the manufacturing methods (reactive extrusion vs. hot press) were investigated to determine the effects of these factors on the physico-mechanical properties of the composites. Finally, a response surface method using a Box-Behnken design was constructed to statistically model and optimize the material compositions-processing conditions-mechanical property relationships of formaldehyde-free wood composite panels. FTIR, 13C NMR, XPS and titration data confirmed the grafting of maleated polyolefins onto wood particles through an esterification reaction, while the level of grafting of MAPE onto wood particles was determined to be a function of the MAPE concentration. However, there was no significant difference in grafting efficiency at different extrusion processing conditions; rather all of the conditions resulted in

  8. Improving Hemostasis during Replacement of the Ascending Aorta and Aortic Valve with a Composite Graft

    OpenAIRE

    Pratali, Stefano; Milano, Aldo; Codecasa, Riccardo; Carlo, Marco De; Borzoni, Giancarlo; Bortolotti, Uberto

    2000-01-01

    The use of a composite graft is an established treatment for patients with aortic valve disease and ascending aortic aneurysms. Since bleeding from suture lines is a potential complication of this procedure, we modified the technique and evaluated the effect on hemostasis.

  9. Stent graft composition plays a material role in the postimplantation syndrome

    NARCIS (Netherlands)

    M.T. Voûte (Michiel); F.M.V. Bastos Gonçalves (Frederico); K.M. van de Luijtgaarden (Koen); C.G.A. Klein Nulent (Casper ); S.E. Hoeks (Sanne); R.J. Stolker (Robert); H.J.M. Verhagen (Hence)

    2012-01-01

    textabstractObjective: In patients undergoing endovascular aneurysm repair (EVAR), the postimplantation syndrome (PIS), comprising fever and inflammation, occurs frequently. The cause of PIS is unclear, but graft composition and acute thrombus formation may play a role. The objective of this study w

  10. Crystallization and recrystallization behavior study on biopolymer composites with polymer grafted halloysite nanotubes

    Science.gov (United States)

    Hsieh, Ya-Ting; Kojio, Ken; Takahara, Atsushi

    We study the crystallization and recrystallization behavior of poly(lactic acid) (PLA) in PLA/halloysite composites. Specifically, we are interested in finding the additional effect of interface properties variation in composites except for enhancing filler dispersion. Halloysite nanotubes are grafted with polymer to create different surface properties at their surface. These polymer grafted halloysite nanotubes are then spread into PLA via solvent mixing. Using differential scanning calorimeter, we track and analyze the influence of halloysite surface properties on the crystallization and recrystallization behavior of PLA composites under several conditions. We also present investigations of polarizing optical microscopy, in-situ Fourier transform infrared spectroscopy, and in-situ synchrotron X-ray diffraction measurements. The investigations provide insight into interface effect on PLA composites. The synchrotron WAXD measurements were performed on BL02B2 beamline at Spring-8 with the approval of the Japan Synchrotron Radiation Institute (JASRI) (Proposal No. 2015B1541).

  11. Methods of Attaching or Grafting Carbon Nanotubes to Silicon Surfaces and Composite Structures Derived Therefrom

    Science.gov (United States)

    Tour, James M. (Inventor); Chen, Bo (Inventor); Flatt, Austen K. (Inventor); Stewart, Michael P. (Inventor); Dyke, Christopher A. (Inventor); Maya, Francisco (Inventor)

    2012-01-01

    The present invention is directed toward methods of attaching or grafting carbon nanotubes (CNTs) to silicon surfaces. In some embodiments, such attaching or grafting occurs via functional groups on either or both of the CNTs and silicon surface. In some embodiments, the methods of the present invention include: (1) reacting a silicon surface with a functionalizing agent (such as oligo(phenylene ethynylene)) to form a functionalized silicon surface; (2) dispersing a quantity of CNTs in a solvent to form dispersed CNTs; and (3) reacting the functionalized silicon surface with the dispersed CNTs. The present invention is also directed to the novel compositions produced by such methods.

  12. Composite ceramic bone graft substitute in the treatment of locally aggressive benign bone tumours.

    OpenAIRE

    Schindler, O. S.; Cannon, S.R.; Briggs, T. W.; Blunn, G. W.

    2008-01-01

    PURPOSE: To report the use of a composite ceramic bone graft substitute containing calcium sulphate and hydroxyapatite (HA) in the treatment of large expansive osteolytic benign bone tumours. METHODS: 4 women and 9 men aged 8 to 49 (mean, 22) years with aneurysmal bone cysts (n=6) or giant cell tumours (n=7) in the epi- or meta-physeal areas of the lower limbs underwent curettage, phenolisation, and filling with bone graft substitute containing calcium sulphate and HA. The mean tumour size wa...

  13. Perichondrium/cartilage composite graft for repairing large tympanic membrane perforations and hearing improvement

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-wei; YANG Hua; GAO Ru-zhen; YU Rong; GAO Zhi-qiang

    2010-01-01

    Background The main risk factors for postoperative failure in tympanoplasties are large perforations that are difficult to repair, annular perforations, and a tympanic membrane (TM) with extensive granular myringitis that require middle ear exploration and mastoidectomy. The aim of this study was to investigate a novel technique of perichondrium/cartilage composite graft for repairing the large TM perforation in the patient of otitis media.Methods Retrospective chart reviews were conducted for 102 patients with large tympanic membrane perforations, who had undergone tympanoplasty from August 2005 to August 2008. Tympanoplasty or tympanomastoidectomy using a perichondrium/cartilage composite graft was analyzed. The tragal or conchal perichondrium/cartilage was used to replace the tympanic membrane in patients.Results Patients aged from 13 to 67 years were followed up in average for 24 months (10-36 months). Seventy-four ears (72.61%) were used the tragal perichondrium/cartilage as graft material and 27 ears (27.39%) were used the conchal perichondrium/cartilage. Graft take was successful in all patients. Postoperative complications such as wound infection, hematoma, or sensorineural hearing loss were not identified. Nine patients (8.82%) had the partial ossicular replacement prosthesis, 14 patients (13.72%) using the autologous curved incus and 79 patients (77.45%) without prosthesis. Successful closure occurred in 92% of the ears. A total of 85.8% patients achieved a postoperative hearing improvement.Conclusions The graft underlay tympanoplasty using perichonddum/cartilage composite is effective for the majority of patients with large perforation. The hearing was improved even if the mastoidectomy was required in the patients with otitis media with extensive granulation.

  14. Osteoconductive composite graft based on bacterial synthesized hydroxyapatite nanoparticles doped with different ions: From synthesis to in vivo studies.

    Science.gov (United States)

    Ahmadzadeh, Elham; Talebnia, Farid; Tabatabaei, Meisam; Ahmadzadeh, Hossein; Mostaghaci, Babak

    2016-07-01

    To repair damaged bone tissues, osteoconductive bone graft substitutes are required for enhancement of the regenerative potential of osteoblast cells. Nanostructured hydroxyapatite is a bioactive ceramic used for bone tissue engineering purposes. In this study, carbonate hydroxyapatite (cHA) and zinc-magnesium substituted hydroxyapatite (Zn-Mg-HA) nanoparticles were synthesized via biomineralization method using Enterobacter aerogenes. The structural phase composition and the morphology of the samples were analyzed using appropriate powder characterization methods. Next, a composite graft was fabricated by using polyvinyl alcohol and both cHA and Zn-Mg-HA samples. In vivo osteogenic potential of the graft was then investigated in a rabbit tibial osteotomy model. Histological, radiological and morphological studies showed that the graft was mineralized by the newly formed bone tissue without signs of inflammation or infection after 4 weeks of implantation. These histomorphometric results suggest that the fabricated graft can function as a potent osteoconductive bone tissue substitute. PMID:26956413

  15. Graft vasculopathy in the skin of a human hand allograft: implications for diagnosis of rejection of vascularized composite allografts.

    Science.gov (United States)

    Kanitakis, Jean; Karayannopoulou, Georgia; Lanzetta, Marco; Petruzzo, Palmina

    2014-11-01

    Whereas vascularized composite allografts often undergo acute rejections early in the postgraft period, rejection manifesting with severe vascular changes (graft vasculopathy) has only been observed on three occasions in humans. We report a hand-allografted patient who developed severe rejection following discontinuation of the immunosuppressive treatment. It manifested clinically with erythematous maculopapules on the skin and pathologically with graft vasculopathy that affected both large vessels and smaller cutaneous ones. The observation that graft vasculopathy can affect skin vessels shows that it is amenable to diagnosis with usual skin biopsy as recommended for the follow-up of these allografts. Graft vasculopathy developing in the setting of vascularized composite allografts likely represents chronic rejection due to under-immunosuppression and, if confirmed, should be included in a future update of the Banff classification of vascularized composite allograft rejection. PMID:25041139

  16. Composite membranes based on a novel benzimidazole grafted PEEK and SPEEK for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongtao; Zhang, Gang; Ma, Wenjia; Zhao, Chengji; Zhang, Yang; Han, Miaomiao; Zhu, Jing; Liu, Zhongguo; Wu, Jing; Na, Hui [Alan G MacDiarmid Institute, College of Chemistry, Jilin University, Changchun 130012 (China)

    2010-10-15

    Poly(ether ether ketone) (PEEK) and sulfonated poly(ether ether ketone) (SPEEK, IEC = 2.07 mequiv.g{sup -1}) have been synthesized via nucleophilic aromatic substitution reaction. Bromomethylated poly(ether ether ketone) (PEEK-Br) is then prepared and reacted with 2-benzimidazolethiol to obtain the benzimidazole grafted poly(ether ether ketone) (PEEK-BI). The structures of PEEK-Br and PEEK-BI are characterized by {sup 1}H NMR spectra. Composite membranes based on SPEEK and PEEK-BI are prepared and their properties used for fuel cells are studied in detail. The results show that the composite membranes exhibit greatly improved mechanical properties as well as reduced water uptake and methanol permeability compared with the pristine SPEEK membrane. The increased oxidative stability and selectivity indicate that the composite membranes are promising to be used as proton exchange membranes. (author)

  17. The composite of bone marrow concentrate and PRP as an alternative to autologous bone grafting.

    Directory of Open Access Journals (Sweden)

    Mohssen Hakimi

    Full Text Available One possible alternative to the application of autologous bone grafts represents the use of autologous bone marrow concentrate (BMC. The purpose of our study was to evaluate the potency of autologous platelet-rich plasma (PRP in combination with BMC. In 32 mini-pigs a metaphyseal critical-size defect was surgically created at the proximal tibia. The animals were allocated to four treatment groups of eight animals each (1. BMC+CPG group, 2. BMC+CPG+PRP group, 3. autograft group, 4. CPG group. In the BMC+CPG group the defect was filled with autologous BMC in combination with calcium phosphate granules (CPG, whereas in the BMC+CPG+PRP group the defect was filled with the composite of autologous BMC, CPG and autologous PRP. In the autograft group the defect was filled with autologous cancellous graft, whereas in the CPG group the defect was filled with CPG solely. After 6 weeks radiological and histomorphometrical analysis showed significantly more new bone formation in the BMC+CPG+PRP group compared to the BMC+CPG group and the CPG group. There were no significant differences between the BMC+CPG+PRP group and the autograft group. In the PRP platelets were enriched significantly about 4.7-fold compared to native blood. In BMC the count of mononuclear cells increased significantly (3.5-fold compared to the bone marrow aspirate. This study demonstrates that the composite of BMC+CPG+PRP leads to a significantly higher bone regeneration of critical-size defects at the proximal tibia in mini-pigs than the use of BMC+CPG without PRP. Furthermore, within the limits of the present study the composite BMC+CPG+PRP represents a comparable alternative to autologous bone grafting.

  18. Synthesis of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes composite for supercapacitance application

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Rajesh Kr., E-mail: r05bhu@gmail.com [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Xingjue, Wang [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Kumar, Vinod [Department of Zoology, Banaras Hindu University, Varanasi (India); Srivastava, Anchal [Department of Physics, Banaras Hindu University, Varanasi (India); Singh, Vidya Nand [CSIR-National Physical Laboratory, New Delhi (India)

    2014-11-05

    Highlights: • We are reporting supercapacitance performance of BI-GO/MWCNTs composite. • The specific capacitance of BI-GO/MWCNTs is 275 and 460 F/g at 200 and 5 mV/s scan rate. • This composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate. - Abstract: We are reporting the fabrication, characterizations and supercapacitance performance of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes (BI-GO/MWCNTs) composite. The synthesis of BI-GO materials involves cyclization reaction of carboxylic groups on GO among the hydroxyl and amino groups on o-phenylenediamine. The BI-GO/MWCNTs composite has been fabricated via in situ reduction of BI-GO using hydrazine in presence of MWCNTs. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize its surface and elemental composition. The uniform dispersion of MWCNTs with BI-GO helps to improve the charge transfer reaction during electrochemical process. The specific capacitance of BI-GO/MWCNTs composite is 275 and 460 F/g at 200 and 5 mV/s scan rate in 1 mol/L aqueous solution of H{sub 2}SO{sub 4}. This BI-GO/MWCNTs composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate, which represents its good electrochemical stability.

  19. Synthesis of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes composite for supercapacitance application

    International Nuclear Information System (INIS)

    Highlights: • We are reporting supercapacitance performance of BI-GO/MWCNTs composite. • The specific capacitance of BI-GO/MWCNTs is 275 and 460 F/g at 200 and 5 mV/s scan rate. • This composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate. - Abstract: We are reporting the fabrication, characterizations and supercapacitance performance of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes (BI-GO/MWCNTs) composite. The synthesis of BI-GO materials involves cyclization reaction of carboxylic groups on GO among the hydroxyl and amino groups on o-phenylenediamine. The BI-GO/MWCNTs composite has been fabricated via in situ reduction of BI-GO using hydrazine in presence of MWCNTs. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize its surface and elemental composition. The uniform dispersion of MWCNTs with BI-GO helps to improve the charge transfer reaction during electrochemical process. The specific capacitance of BI-GO/MWCNTs composite is 275 and 460 F/g at 200 and 5 mV/s scan rate in 1 mol/L aqueous solution of H2SO4. This BI-GO/MWCNTs composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate, which represents its good electrochemical stability

  20. The effects of the chemical composition of titanate nanotubes and solvent type on 3-aminopropyltriethoxysilane grafting efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Pontón, Patricia I., E-mail: patriciapontonb@aluno.puc-rio.br [Department of Materials Engineering, Pontifical Catholic University of Rio de Janeiro, CP 38008, 22453-900 Rio de Janeiro, RJ (Brazil); D’Almeida, José R.M.; Marinkovic, Bojan A. [Department of Materials Engineering, Pontifical Catholic University of Rio de Janeiro, CP 38008, 22453-900 Rio de Janeiro, RJ (Brazil); Savić, Slavica M. [Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade (Serbia); Mancic, Lidija [Institute of Technical Sciences of SASA, Knez Mihailova 35/IV, Belgrade (Serbia); Rey, Nicolás A. [Department of Chemistry, Pontifical Catholic University of Rio de Janeiro, CP 38008, 22453-900 Rio de Janeiro, RJ (Brazil); Morgado, Edisson [Petrobras S.A./CENPES, Research and Development Centre, Av. Horácio Macedo, 950 Cidade Universitária, 21949-900 Rio de Janeiro, RJ (Brazil); Rizzo, Fernando C. [Department of Materials Engineering, Pontifical Catholic University of Rio de Janeiro, CP 38008, 22453-900 Rio de Janeiro, RJ (Brazil)

    2014-05-01

    Graphical abstract: - Highlights: • Titanate nanotubes (TTNT) were modified with 3-aminopropyltriethoxysilane (APTES). • Effects of TTNT sodium content and solvent on APTES grafting efficiency were studied. • Aqueous ethanol was a more efficient reaction medium for functionalization of TTNT. • Within aqueous ethanol TTNT with low sodium content were more efficiently grafted. • Grafting of APTES on TTNT surface occurs through Ti–O–Si primary chemical bonding. - Abstract: One of the major challenges in the development of nanocomposites based on a polymer matrix and highly polar ceramic nanofillers is the lack of the compatibility between these two components. In order to improve the chemical interaction between titanate nanotubes (TTNT) and polymer matrix, such as nylon 11,3-aminopropyltriethoxysilane (APTES) was grafted onto TTNT. The effects of the TTNT chemical composition i.e. sodium content and solvent type on the grafting silane efficiency were thoroughly studied through CHN elemental analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), surface area and zeta potential measurements. The present study brings evidences supporting aqueous ethanol as more efficient reaction medium for TTNT functionalization with APTES, independent of the sodium content of nanotubes, when compared with pure water. It is also worth noting that within aqueous ethanol medium, TTNT with low sodium content are more efficiently grafted than TTNT with high sodium content. Successful APTES grafting decreases concentration of the hydroxyl groups on TTNT surfaces and enables its future application for the fabrication of nylon 11 nanocomposites.

  1. The effects of the chemical composition of titanate nanotubes and solvent type on 3-aminopropyltriethoxysilane grafting efficiency

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Titanate nanotubes (TTNT) were modified with 3-aminopropyltriethoxysilane (APTES). • Effects of TTNT sodium content and solvent on APTES grafting efficiency were studied. • Aqueous ethanol was a more efficient reaction medium for functionalization of TTNT. • Within aqueous ethanol TTNT with low sodium content were more efficiently grafted. • Grafting of APTES on TTNT surface occurs through Ti–O–Si primary chemical bonding. - Abstract: One of the major challenges in the development of nanocomposites based on a polymer matrix and highly polar ceramic nanofillers is the lack of the compatibility between these two components. In order to improve the chemical interaction between titanate nanotubes (TTNT) and polymer matrix, such as nylon 11,3-aminopropyltriethoxysilane (APTES) was grafted onto TTNT. The effects of the TTNT chemical composition i.e. sodium content and solvent type on the grafting silane efficiency were thoroughly studied through CHN elemental analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), surface area and zeta potential measurements. The present study brings evidences supporting aqueous ethanol as more efficient reaction medium for TTNT functionalization with APTES, independent of the sodium content of nanotubes, when compared with pure water. It is also worth noting that within aqueous ethanol medium, TTNT with low sodium content are more efficiently grafted than TTNT with high sodium content. Successful APTES grafting decreases concentration of the hydroxyl groups on TTNT surfaces and enables its future application for the fabrication of nylon 11 nanocomposites

  2. Modifying glass fiber surface with grafting acrylamide by UV-grafting copolymerization for preparation of glass fiber reinforced PVDF composite membrane.

    Science.gov (United States)

    Luo, Nan; Zhong, Hui; Yang, Min; Yuan, Xing; Fan, Yaobo

    2016-01-01

    Experimental design and response surface methodology (RSM) were used to optimize the modification of conditions for glass surface grafting with acrylamide (AM) monomer for preparation of a glass fiber reinforced poly(vinylidene fluoride) (PVDF) composite membrane (GFRP-CM). The factors considered for experimental design were the UV (ultraviolet)-irradiation time, the concentrations of the initiator and solvent, and the kinds and concentrations of the silane coupling agent. The optimum operating conditions determined were UV-irradiation time of 25 min, an initiator concentration of 0-0.25 wt.%, solvent of N-Dimethylacetamide (DMAC), and silane coupling agent KH570 with a concentration of 7 wt.%. The obtained optimal parameters were located in the valid region and the experimental confirmation tests conducted showed good accordance between predicted and experimental values. Under these optimal conditions, the water absorption of the grafted modified glass fiber was improved from 13.6% to 23%; the tensile strength was enhanced and the peeling strength of the glass fiber reinforced PVDF composite membrane was improved by 23.7% and 32.6% with an AM concentration at 1 wt.% and 2 wt.%. The surface composition and microstructure of AM grafted glass fiber were studied via several techniques including Field Emission Scanning Electron Microscopy (FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and energy dispersive X-ray spectroscopy (EDX). The analysis of the EDX and FTIR-ATR results confirmed that the AM was grafted to the glass fiber successfully by detecting and proving the existence of nitrogen atoms in the GFRP-CM. PMID:26899659

  3. Preparation of chitosan grafted graphite composite for sensitive detection of dopamine in biological samples.

    Science.gov (United States)

    Palanisamy, Selvakumar; Thangavelu, Kokulnathan; Chen, Shen-Ming; Gnanaprakasam, P; Velusamy, Vijayalakshmi; Liu, Xiao-Heng

    2016-10-20

    The accurate detection of dopamine (DA) levels in biological samples such as human serum and urine are essential indicators in medical diagnostics. In this work, we describe the preparation of chitosan (CS) biopolymer grafted graphite (GR) composite for the sensitive and lower potential detection of DA in its sub micromolar levels. The composite modified electrode has been used for the detection of DA in biological samples such as human serum and urine. The GR-CS composite modified electrode shows an enhanced oxidation peak current response and low oxidation potential for the detection of DA than that of electrodes modified with bare, GR and CS discretely. Under optimum conditions, the fabricated GR-CS composite modified electrode shows the DPV response of DA in the linear response ranging from 0.03 to 20.06μM. The detection limit and sensitivity of the sensor were estimated as 0.0045μM and 6.06μA μM(-1)cm(-2), respectively. PMID:27474582

  4. Oleic acid-grafted chitosan/graphene oxide composite coating for corrosion protection of carbon steel.

    Science.gov (United States)

    Fayyad, Eman M; Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Al-Maadeed, Mariam Al Ali

    2016-10-20

    An anticorrosion coating film based on the formation of nanocomposite coating is reported in this study. The composite consisted of chitosan (green matrix), oleic acid, and graphene oxide (nano filler). The nanocomposite coating was arranged on the surface of carbon steel, and the corrosion resistance was monitored using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP). Compared to the pure chitosan (CS) coating, the corrosion resistance of oleic acid-modified chitosan/graphene oxide film (CS/GO-OA) is increased by 100 folds. Since the well-dispersed smart grafted nanolayers delayed the penetration rate of corrosive species and thus maintained long term anticorrosive stability which is correlated with hydrophobicity and permeability. PMID:27474635

  5. Clinical study of reconstructing the medial malleolus with free grafting of fibular head composite tendon bone flap

    Institute of Scientific and Technical Information of China (English)

    WU Shui-pei

    2008-01-01

    Objective: To explore new surgical procedure for repairing and reconstructing medial malleolus and soft tissue defect.Methods: According to the size of medial malleolus and composite soft tissue defect, vascular fibular head composite tendon bone flap free grafting using anterior tibial recurrent vessel as the perforating branch was designed to reconstruct the medial malleolar saddle and triangular ligament, and composite back broadest muscle flap free grafting was designed to repair the medical malleolar wound surface. From January 2000 to December 2006, the technique was used in 5 male patients who were injured by machine or in traffic accidents, causing bone and soft tissue defect. The size of wound surface ranged from 19 cm×12 cm to 24 cm×12 cm.Results: The wound surface was healed at the first stage in 4 cases, and the other case had infection and was cured in 6 months with anti infection therapy. Postoperative follow-ups from 6 months to 6 years showed that grafted bones and free cutaneous flaps were healed well, malleolar joints were stable, joint movement was normal, and the appearance was satisfactory. The overall outcome was good.Conclusion: Fibular head composite tendon bone flap free grafting is effective for repairing medical malleolar defect.

  6. Potassium diperiodatocuprate-mediated preparation of poly(methyl methacrylate/organo-montmorillonite composites via in situ grafting copolymerization

    Directory of Open Access Journals (Sweden)

    2008-09-01

    Full Text Available In this study, potassium diperiodatocuprate (Cu3+ was selected as an initiator to prepare poly(methyl methacrylate/organo-montmorillonite composites (OMMT-g-PMMA by in situ graft copolymerization. Three synthetic parameters were systematically evaluated as a function of the temperature, the concentration of initiator, pH and the ratio of MMA to OMMT. It was found that Cu3+ was a highly efficient initiator for the preparation of OMMT-g-PMMA i.e., monomer conversion and grafting efficiency were as higher as 95%. The X-ray diffraction measurement showed the intercalation of PMMA chains into OMMT layers on base of an increasing basal spacing after polymerization. FTIR analysis also suggested that the PMMA chains were effectively grafted onto OMMT substrate. The enhanced thermal stabilities of OMMT-g-PMMA composites were confirmed by the thermal gravimetric analysis (TGA. Finally, a single-electron-transfer mechanism was proposed to illustrate the formation of radicals and the preparation process of OMMT-g-PMMA composites. Cu3+ can be used as an effective and practical initiator in preparing the organic/inorganic composite due to its high grafting efficiency and the milder reaction condition.

  7. Estimation of compositional heterogeneity of poly(4-methylstyrene-graft-2vinylpyridine) by combination of chromatographic methods

    Czech Academy of Sciences Publication Activity Database

    Trhlíková, Olga; Netopilík, Miloš; Janata, Miroslav; Svitáková, Romana; Berek, D.

    Pardubice: RADANAL Ltd, 2014 - (Horna, A.; Jandera, P.). s. 127 ISBN 978-80-7395-777-3. [International Symposium on Separation Sciences /20./ - ISSS 2014. 30.8.2014-02.09.2014, Prague] R&D Projects: GA ČR(CZ) GA13-02938S Institutional support: RVO:61389013 Keywords : liquid chromatography * graft copolymer * compositional heterogeneity Subject RIV: CD - Macromolecular Chemistry

  8. Posterolateral spinal fusion in a rabbit model using a collagen–mineral composite bone graft substitute

    OpenAIRE

    Walsh, William Robert; Vizesi, F.; Cornwall, G. B.; Bell, D; Oliver, R.; Yu, Y.

    2009-01-01

    Choosing the appropriate graft material to participate in the healing process in posterolateral spinal fusion continues to be a challenge. Combining synthetic graft materials with bone marrow aspirate (BMA) and autograft is a reasonable treatment option for surgeons to potentially reduce or replace the need for autograft. FormaGraft, a bone graft material comprising 12% bovine-derived collagen and 88% ceramic in the form of hydroxyapatite (HAp) and beta tricalcium phosphate (β-TCP) was evalua...

  9. Sensing of environmental pollutant by conductive composite from prepared from hyperbranched polymer-grafted carbon black and crystalline polymer

    International Nuclear Information System (INIS)

    Complete text of publication follows. The hyperbranched (HB) polymer-grafted (PG) carbon blacks (CB) have the possibility of utilizing as a support of catalyst and enzyme, and a curing agent of epoxy resin, because they have much terminal amino or hydroxyl groups. The postgrafting of crystalline polymer onto HB PG CB and the sensing of environmental pollutant by the conductive composite prepared from the polymer-postgrafted CB was discussed. The grafting of poly(amidoamide) onto CB surface was achieved by repeating either Michael addition of methyl acrylate to amino group on the surface or the amidation of the resulting terminal methyl ester group with ethylene diamine. HB polyester onto CB surface was grafted by stepwise growth of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) from surface carboxyl and hydroxyl groups on CB as a core in the presence of p-toluenesulfonic acid (p-TSA). The one-pot grafting of HB polyester onto CB as core was also achieved by the polycondensation of bis-MPA in the presence of p-TSA. Postgrafting of crystalline polymer onto HB polymer-grafted CB was achieved by the reaction of terminal amino or hydroxyl groups of grafted chain with COCl-terminated crystalline polymer. The electric resistance of the composite prepared from crystalline polymer-postgrafted CB was found to increase drastically in hexane, containing environmental pollutant, such as chloroform and trichloroethane, and returned immediately to the initial resistance when it was transferred into pure hexane. Based on the above results, it is concluded that the composite can be used as a novel sensor for environmental pollutant in solution

  10. Synthesis and Characterization of Styrene- Ethylene-Propylene-Styrene (SEPS Grafted with Maleic Anhydride (MAH for Use as Coupling Agent in Wood Polymer Composite

    Directory of Open Access Journals (Sweden)

    M. Acevedo-Morantes

    2015-10-01

    Full Text Available Styrene-Ethylene-Propylene-Styrene (SEPS block copolymer was grafted with maleic anhydride (MAH by reactive extrusion (SEPS-g-MAH using an organic peroxide as initiator in the grafting. SEPS-g-MAH was synthesized for use as coupling agent in wood polymer composite (WPC. Identification of this compatibilizer was made using Fourier transform infrared spectroscopy (FTIR and the grafting degree was determinate with titration. The characteristic peaks in FTIR analysis indicated the presence of MAH in the copolymer.

  11. Synthesis and Characterization of Styrene- Ethylene-Propylene-Styrene (SEPS) Grafted with Maleic Anhydride (MAH) for Use as Coupling Agent in Wood Polymer Composite

    OpenAIRE

    M. Acevedo-Morantes; Tapia, A.; Correa, J. (José); A. Realpe-Jimenez; C. Gartner

    2015-01-01

    Styrene-Ethylene-Propylene-Styrene (SEPS) block copolymer was grafted with maleic anhydride (MAH) by reactive extrusion (SEPS-g-MAH) using an organic peroxide as initiator in the grafting. SEPS-g-MAH was synthesized for use as coupling agent in wood polymer composite (WPC). Identification of this compatibilizer was made using Fourier transform infrared spectroscopy (FTIR) and the grafting degree was determinate with titration. The characteristic peaks in FTIR analysis indicated the presence o...

  12. The effect of bone marrow aspirate, bone graft and collagen composites on fixation of bone implants

    DEFF Research Database (Denmark)

    Babiker, Hassan; Ding, Ming; Overgaard, Søren

    2007-01-01

     Introduction: Replacement of extensive local bone loss especially in revision joint arthroplasties is a significant clinical challenge. Autogenous and allogenic cancellous bone grafts have been the gold standard in reconstructive orthopaedic surgery, but it is well known that there is morbidity...... associated with harvesting of autogenous bone graft and limitations in the quantity of bone available. Disadvantages of allograft include the risk of bacterial or viral contamination and non union as well as the potential risk of disease transmission. Alternative options are attractive and continue to be...... sought. Hydroxyapatite and collagen composites have the potential in mimicking and replacing skeletal bones. Aim: This study attempted to determine the effect of hydroxyapatite/collagen composites in the fixation of bone implants. The composites used in this study is produced by Institute of Science and...

  13. Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide

    Directory of Open Access Journals (Sweden)

    B. Qi

    2014-07-01

    Full Text Available Graphene oxide (GO sheets were chemically grafted with thermotropic liquid crystalline epoxy (TLCP. Then we fabricated composites using TLCP-g-GO as reinforcing filler. The mechanical properties and thermal properties of composites were systematically investigated. It is found that the thermal and mechanical properties of the composites are enhanced effectively by the addition of fillers. For instance, the composites containing 1.0 wt% of TLCP-g-GO present impact strength of 51.43 kJ/m2, the tensile strength of composites increase from 55.43 to 80.85 MPa, the flexural modulus of the composites increase by more than 48%. Furthermore, the incorporation of fillers is effective to improve the glass transition temperature and thermal stability of the composites. Therefore, the presence of the TLCP-g-GO in the epoxy matrix could make epoxy not only stronger but also tougher.

  14. Composite vascular grafts with high cell infiltration by co-electrospinning.

    Science.gov (United States)

    Tan, Zhikai; Wang, Hongjie; Gao, Xiangkai; Liu, Tong; Tan, Yongjun

    2016-10-01

    There is an increasing demand for functional small-diameter vascular grafts (diameterpolycaprolactone, gelatin, and polyvinyl alcohol (PVA) by co-electrospinning, and the scaffolds were further functionalized by immobilizing heparin on them. The PVA fibers degraded rapidly in vivo and generated electrospun scaffolds with high porosity, which significantly enhanced cell proliferation and infiltration. The mechanical properties of the grafts are suitable for use in artery replacement. Heparin functionalization of the grafts yielded a good antithrombogenic effect, which was demonstrated in platelet adhesion tests. Moreover, in vitro and in vivo results demonstrated that the heparin release from the grafts enhanced the growth of endothelial cells, which is important for the endothelium of implanted grafts. The results of this study indicate that our method is effective and controllable for the fabrication of vascular grafts that meet the clinical requirements for blood vessel transplantation. PMID:27287133

  15. Evolution of watermelon fruit physicochemical and phytochemical composition during ripening as affected by grafting.

    Science.gov (United States)

    Soteriou, G A; Kyriacou, M C; Siomos, A S; Gerasopoulos, D

    2014-12-15

    Flesh reflectance colorimetry, mechanical texture analysis, pH, titratable acidity (TA), and soluble solid (SS), soluble carbohydrate, lycopene and citrulline content of watermelon fruit were assessed throughout ripening (30-50 days post-anthesis; dpa) in grafted and self-rooted plants. Grafting increased firmness, TA, and lycopene content though it delayed its peak. Lycopene content was mostly ripening-dependant, highly correlated and synchronous with changes in pulp chroma (C) and colour a. The sweetness was affected only by ripening. However, total sugars and SS peaked later in fruit of grafted plants than in non-grafted ones, and significant interaction of ripening with grafting was observed. Citrulline content increased with ripening in fruit of grafted plants, reaching a peak at 45 dpa; whereas in non-grafted ones it was unchanged between 30 and 45 dpa and declined at 50 dpa. As ripening overall was retarded by grafting, fruit quality of grafted watermelon may benefit from belated harvest. PMID:25038677

  16. Pre-PET Graft Modification of Nano-ZrO2 and Its Effect on Mechanical Property of PC Composites

    Institute of Scientific and Technical Information of China (English)

    LI Li; SHI Li-yi; CAO Shao-mei; FENG Xin; ZHANG Yu

    2009-01-01

    Nano-ZrO2 panicles were modified by poly ( ethylene terephalate ) prepolymer ( pre-PET ) via polycondensation. FT-IR, TEM, and TGA results showed that pre-PET was successfully grafted on the surface of uano-ZrO2 particles. Compared to the original nano-ZrO2, the grafted nano-ZrO2 had better compatibility with the polycarbonate (PC) matrix and could be dispersed more homogeneously in PC. Hence, interracial adhesion between ZrO2 and PC was enhanced. The mechanical properties of the resultant PC/nano-ZrO2 composite like tensile strength and notched impact strength were greatly improved. Calculated respectively from tensile yield stress PC/nano-ZrO2 composites, the interfacial interaction parameter B was employed to quantitatively characterize the effective interfacial interaction between the nano-ZrO2 and PC matrix.

  17. Preparation of composite polymer electrolytes by electron beam-induced grafting: Proton- and lithium ion-conducting membranes

    International Nuclear Information System (INIS)

    Two classes of composite polymer electrolyte membranes, one conducting lithium ions (Li+) and the other conducting protons (H+) were prepared using simultaneous electron beam-induced grafting. Porous poly(vinylidene fluoride) (PVDF) films were impregnated with styrene and subjected to electron beam (EB) irradiation to obtain polystyrene (PS) filled PVDF precursor films that were subsequently treated with either chlorosulfonic acid/1,1,2,2-tetrachloroethane mixture to obtain H+-conducting composite membranes or LiPH6/EC/DEC liquid electrolyte to obtain Li+-conducting composite membranes. The properties of the obtained membranes were evaluated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and AC impedance measurements. The obtained membranes were found to achieve grafting content up to 46% with superior Li+-conductivity of 1.91 x 10-3 S/cm and H+-conductivity of 5.95 x 10-2 S/cm. The results of this work show that simultaneous radiation-induced grafting with EB is a promising method to prepare high quality ion-conducting membranes for possible use in fuel cells and lithium batteries

  18. Mutual irradiation grafting on indigenous aramid fiber-3 in diethanolamine and epichlorohydrin and its effect on interfacially reinforced epoxy composite

    Science.gov (United States)

    Xing, Lixin; Liu, Li; Xie, Fei; Huang, Yudong

    2016-07-01

    The surface of indigenous aramid fiber-3 (IAF3) was decorated via mutual irradiation grafting process in diethanolamine (DEA) and epichlorohydrin (ECH), respectively, with the assist of high energy gamma rays. This modification method with great permeability produced the homogeneous and ameliorative AF3 surfaces, which were observed by the scanning electron microscopy (SEM) and atom forced microscopy (AFM). Enhanced surface free energy and reduced contact angles of irradiated AF3 verified the fabulous effectiveness of mutual irradiation without seriously injured tensile strength. The composites based on epoxy resin (ER) polymer as the matrix and irradiated IAF3 grafted DEA and ECH as the reinforcement. By capitalizing on the irradiated IAF3 which has higher wettability and adsorption on resin, the irradiated IAF3-ECH/ER composites exhibit admirable interfacial mechanical performance as compared to the pristine IAF3 contained composites. The interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and flexural strength of composites were remarkable improved to 86.5, 60.13 and 511 MPa respectively, from the pristine IAF3/ER composite with IFSS of 65.9 MPa, ILSS of 48.1 MPa, and flexural strength of 479 MPa.

  19. Highly grafted polystyrene/polyvinylpyridine polymer gold nanoparticles in a good solvent: effects of chain length and composition.

    Science.gov (United States)

    Posel, Zbyšek; Posocco, Paola; Lísal, Martin; Fermeglia, Maurizio; Pricl, Sabrina

    2016-04-21

    In this work, the structural features of spherical gold nanoparticles (NPs) decorated with highly grafted poly(styrene) (PS), poly(vinylpyridine) (PVP) and PS-PVP diblock copolymer brushes immersed in a good solvent are investigated by means of Dissipative Particle Dynamics (DPD) simulations as a function of grafted chain length and of homopolymer and copolymer chain composition. For NPs grafted either by PS or PVP homopolymer brushes (selected as a proof of concept), good agreement between the Daoud-Cotton theory, experimental evidence, and our DPD simulations is observed in the scaling behavior of single chain properties, especially for longer grafted chains, and in brush thickness prediction. On the other hand, for grafted chain lengths comparable to NP dimensions parabolic-like profiles of the end-monomer distributions are obtained. Furthermore, a region of high concentration of polymer segments is observed in the monomer density distribution for long homopolymers. In the case of copolymer-decorated NPs, the repulsion between PS and PVP blocks is found to substantially influence the radius of gyration and the shape of the end-monomer distribution of the relevant polymer shell. Moreover, for diblock chains, the un-swollen region is observed to be thinner (and, correspondingly, the swollen layer thicker) than that of a NP modified with a homopolymer of the same length. Finally, the lateral segregation of PS and PVP blocks is evidenced by our calculations and a detailed analysis of the corona behavior is reported, thus revealing the key parameters in controlling the surface properties and the response of diblock copolymer modified nanoparticles. PMID:26980360

  20. Boron Nitride Nanosheets (BNNSs) Chemically Modified by "Grafting-From" Polymerization of Poly(caprolactone) for Thermally Conductive Polymer Composites.

    Science.gov (United States)

    Lee, Jinseong; Jung, Haejong; Yu, Seunggun; Man Cho, Suk; Tiwari, Vimal K; Babu Velusamy, Dhinesh; Park, Cheolmin

    2016-07-01

    To meet the growing demand for rapid heat dissipation in electronic devices to ensure their reliable performance with a high level of safety, many polymer composites with thermally conductive but electrically insulating 2D boron nitride nanosheets (BNNSs) are being developed. Here we present an efficient way to enhance the thermal conductivity (TC) of a polymer composite by means of "grafting-from" polymerization of a poly(caprolactone) (PCL) onto BNNSs. The BNNSs, which were exfoliated from bulk BN by means of ultra-sonication, were prepared by means of radical oxidation. These oxidized BNNSs (oxi-BNNSs) were employed as initiators for subsequent ring-opening polymerization of PCL, which successfully resulted in PCL chemically grafted onto BNNSs (PCL-g-BNNSs). The excellent dispersion of PCL-g-BNNSs in common solvents allowed us to readily fabricate a polymer composite that contained PCL-g-BNNSs embedded in a PCL matrix, and the composite showed TC values that were five and nine times greater in the out-of-plane and in-plane mode, respectively, than those of pristine PCL. PMID:27283727

  1. New Composition of Maleic-Anhydride-Grafted Poly(Lactic Acid)/Rice Husk with Methylenediphenyl Diisocyanate

    OpenAIRE

    Tsou, Chi-Hui; Hung, Wei-Song; Chin-San WU; Chen, Jui-Chin; Chi-Yuan HUANG; Chiu, Shih-Hsuan; Chih-Yuan TSOU; Yao, Wei-Hua; Shang-Ming LIN; Chih-Kuei CHU; Hu, Chien-Chieh; Kueir-Rarn LEE; Suen, Maw-Cherng

    2014-01-01

    Maleic-anhydride-grafted poly(lactic acid) (PLA-g-MAH) was prepared and blended with rice husk (RH). Methylenediphenyl diisocyanate (MDI) was used as the coupling agent for combining RH with PLA-g-MAH, which improved the poor interfacial adhesion between PLA and RH. Various PLA-g-MAH/RH blends, with and without MDI, were prepared by melt processing using a brabender. The effects that inclusion and distribution of MDI had on the mechanical properties and thermal behaviors of the composites wer...

  2. Skin graft

    Science.gov (United States)

    Skin transplant; Skin autografting; FTSG; STSG; Split thickness skin graft; Full thickness skin graft ... site. Most people who are having a skin graft have a split-thickness skin graft. This takes ...

  3. Development of corn starch based green composites reinforced with Saccharum spontaneum L fiber and graft copolymers--evaluation of thermal, physico-chemical and mechanical properties.

    Science.gov (United States)

    Kaith, B S; Jindal, R; Jana, A K; Maiti, M

    2010-09-01

    In this paper, corn starch based green composites reinforced with graft copolymers of Saccharum spontaneum L. (Ss) fiber and methyl methacrylates (MMA) and its mixture with acrylamide (AAm), acrylonitrile (AN), acrylic acid (AA) were prepared. Resorcinol-formaldehyde (Rf) was used as the cross-linking agent in corn starch matrix and different physico-chemical, thermal and mechanical properties were evaluated. The matrix and composites were found to be thermally more stable than the natural corn starch backbone. Further the matrix and composites were subjected for biodegradation studies through soil composting method. Different stages of biodegradation were evaluated through FT-IR and scanning electron microscopic (SEM) techniques. S. spontaneum L fiber-reinforced composites were found to exhibit better tensile strength. On the other hand Ss-g-poly (MMA) reinforced composites showed maximum compressive strength and wear resistance than other graft copolymers reinforced composite and the basic matrix. PMID:20395134

  4. Mesoporous silica/polyacrylamide composite: Preparation by UV-graft photopolymerization, characterization and use as Hg(II) adsorbent

    Science.gov (United States)

    Saad, Ali; Bakas, Idriss; Piquemal, Jean-Yves; Nowak, Sophie; Abderrabba, Manef; Chehimi, Mohamed M.

    2016-03-01

    MCM-41 ordered mesoporous silica was prepared, aminosilanized and grafted with polyacrylamide (PAAM) through in situ radical photopolymerization process. The resulting composite, denoted PAAM-NH2-MCM-41, the calcined and silanized reference MCM-41s were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N2 physisorption at 77 K. These complementary techniques brought strong supporting evidence for the silanization process followed by PAAM grafting. The surface composition was found to be PAAM-rich as judged by XPS. The composite was then employed for the uptake of Hg(II) from aqueous solutions. Adsorption was monitored versus pH, time, and temperature. The maximum adsorption capacity at 25 °C and pH 5.2 was 177 mg g-1. Kinetically, the equilibrium was reached within 60 min for a 100 mg L-1 mercury solution. The adsorption of Hg(II) on PAAM-NH2-MCM-41 composites followed second order kinetics. Thermodynamic parameters suggested that the favorable adsorption process is exothermic in nature and the adsorption is ascribed to a decrease in the degree of freedom of adsorbed ions which results in the entropy change. This work conclusively shows that mesoporous silica-polymer hybrid metal ion adsorbents (with robust silica-polymer interface) can be prepared in a simple way by in situ radical photopolymerization in the presence of aminosilanized silica acting as a support and a macro-hydrogen donor simultaneously.

  5. The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO2

    Directory of Open Access Journals (Sweden)

    Linda S. Schadler

    2012-01-01

    Full Text Available This study demonstrated a method for toughening a highly crosslinked anhydride cured DGEBA epoxy using rubbery block copolymer grafted SiO2 nanoparticles. The particles were synthesized by a sequential reversible addition-fragmentation chain transfer (RAFT polymerization. The inner rubbery block poly(n-hexyl methacrylate (PHMA had a glass transition temperature below room temperature. The outer block poly(glycidyl methacrylate (PGMA was matrix compatible. A rubbery interlayer thickness of 100% and 200% of the particle core radius was achieved by grafting a 20 kg/mol and a 40 kg/mol PHMA at a graft density of 0.7 chains/nm2 from the SiO2 surface. The 20 kg/mol rubbery interlayer transferred load more efficiently to the SiO2 cores than the 40 kg/mol rubbery interlayer and maintained the epoxy modulus up to a loading of 10 vol% of the rubbery interlayer. Both systems enabled cavitation or plastic dilatation. Improvement of the strain-to-break and the tensile toughness was found in both systems. We hypothesize that plastic void growth in the matrix is the primary mechanism causing the improvement of the ductility.

  6. Nano-composite of poly(L-lactide) and halloysite nanotubes surface-grafted with L-lactide oligomer under microwave irradiation.

    Science.gov (United States)

    Luo, Bing-Hong; Hsu, Chung-En; Li, Jian-Hua; Zhao, Liang-Feng; Liu, Ming-Xian; Wang, Xiao-Ying; Zhou, Chang-Ren

    2013-04-01

    In order to improve the bonding between halloysite nanotubes (HNTs) and poly(L-lactide) (PLLA), and hence to increase the mechanical properties of HNTs/PLLA nano-composite, HNTs were surface-grafted with PLLA under microwave irradiation and then blended with PLLA matrix. The optimal conditions for grafting polymerization are: irradiation time of 30 min, microwave power of 30 W and reaction temperature of 130 degrees C. The structure and properties of the surface-grafted HNTs (g-HNTs) were characterized by Fourier transformation infrared (FTIR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and dynamic light scattering (DLS). Nano-composites of g-HNTs/PLLA and non-grafted HNTs/PLLA were subsequently evaluated in terms of crystallinity, dispersion, interfacial interaction, mechanical performance and cytocompatibility by polarized optical microscopy (POM), field scanning electron microscope (FESM), tensile testing and cell culture experiment. Results show that the grafted PLLA chains on the surfaces of HNTs, as inter-tying molecules, played an important role in improving the adhesive strength between the nanotubes and the polymer matrix. The enhanced interaction among g-HNTs and PLLA matrix resulted in a better tensile strength and modulus compared to the pristine PLLA and HNTs/PLLA. Cell culture results indicated that g-HNTs promoted both adhesion and proliferation of M3T3 fibroblasts on the g-HNTs/PLLA composite film. PMID:23621025

  7. New Composition of Maleic-Anhydride-Grafted Poly(Lactic Acid/Rice Husk with Methylenediphenyl Diisocyanate

    Directory of Open Access Journals (Sweden)

    Chi-Hui TSOU

    2014-12-01

    Full Text Available Maleic-anhydride-grafted poly(lactic acid (PLA-g-MAH was prepared and blended with rice husk (RH. Methylenediphenyl diisocyanate (MDI was used as the coupling agent for combining RH with PLA-g-MAH, which improved the poor interfacial adhesion between PLA and RH. Various PLA-g-MAH/RH blends, with and without MDI, were prepared by melt processing using a brabender. The effects that inclusion and distribution of MDI had on the mechanical properties and thermal behaviors of the composites were examined. The results showed that the PLAXRHYMDI specimens had the optimum tensile properties compared with the PLAXRHY, PLA-g-MAHXRHY, and PLA-g-MAHXRHYMDI specimens. The new method of combining MDI and MAH through grafting was expected to be an excellent strategy for mitigating the low functionality of commercial PLA. Possible reasons accounting for the interesting results on tensile strength and thermal properties of the specimens are proposed. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6034

  8. Swelling Behaviors and Characterization of Oil Palm Empty Fruit Bunch-Graft-Poly (Acrylamide) Super absorbent Polymer Composites

    International Nuclear Information System (INIS)

    The development on a class of technologically advanced materials like super absorbent polymer composites (SAPC) involved multidisciplinary research started when its potential is recognized. Oil palm empty fruit bunch-graft-poly (acrylamide) (OPEFB-g-PAAm) SAPC was synthesized via simultaneous crosslinking and graft copolymerization of acrylamide (AAm) monomer onto OPEFB backbone with N,N'-methylenebisacrylamide (MBA) and ammonium persulphate (APS) acts as crosslinked and initiator, respectively, along with neutralization using solution polymerization method. Systematically, variables that affect the swelling behaviors of OPEFB-g-PAAm SAPC were optimized. The effects of initiator, crosslinked and filler concentration as well as solvent quantity and the degree of neutralization on water absorbency of OPEFB-g-PAAm SAPC were studied. Maximum absorbency of OPEFB-g-PAAm SAPC was achieved at 589.06 g/ g when the amount of APS and MBA were 1.5 wt. % and 0.15 wt. %, respectively, and the OPEFB loading was at 10 wt. %. The optimum amount of solvent used was 15 mL and the degree of neutralization was 20 %. The chemical structure of the OPEFB-g-PAAm SAPC was characterized by means of Fourier transform infrared (FTIR) spectroscopy. A mechanism pathway in synthesizing OPEFB-g-PAAm SAPC was suggested. (author)

  9. Reconstruction of Traumatic Composite Tissue Defect of Medial Longitudinal Arch With Free Osteocutaneous Fibular Graft.

    Science.gov (United States)

    Unal, Mehmet Bekir; Seker, Ali; Demiralp, Bahtiyar; Sahin, Mustafa; Cift, Hakan Turan; Oltulu, Ismail

    2016-01-01

    A 34-year-old male sustained a crush injury resulting in bone and soft tissue loss along the medial longitudinal arch of his left foot. Specifically, the injury resulted in loss of first metatarsal without injury to the medial cuneiform or proximal phalanx, fracture of the third metatarsal, and a 5-cm × 9-cm soft tissue defect overlying the dorsomedial aspect of the right foot. After debridement and daily wound care, the defect was subsequently reconstructed using a free osteocutaneous fibular graft. Approximately 6 months after reconstructive surgery, the patient returned to his job without pain, and his pedogram showed almost equal weightbearing distribution on both feet. PMID:25459091

  10. Immediate reconstruction of mandibular defects with a composite sternocleidomastoid musculoclavicular graft

    International Nuclear Information System (INIS)

    The problem of mandibular reconstruction has been approached using many surgical techniques. This article studies one such approach--reconstruction using full-thickness clavicle pedicled on the sternocleidomastoid muscle. Five patients with stage II and stage III carcinoma of the anterior part of the floor of the mouth were treated with mandibular resection and neck dissection. The resulting defects were immediately reconstructed with the clavicle-sternocleidomastoid muscle technique. The patients were observed from one to three years and were examined postoperatively with technetium Tc 99m medronate scans, which demonstrated the grafts to be viable. The technique proved reliable in a limited clinical trial

  11. The significance of grafting collagen on polycaprolactone composite scaffolds: processing-structure-functional property relationship.

    Science.gov (United States)

    Kiran, S; Nune, K C; Misra, R D K

    2015-09-01

    The study concerns processing-structure-functional property relationship in organic-inorganic hybrid scaffolds based on grafted collagen for bone tissue engineering. Biodegradable polyester, polycaprolactone (PCL) and nanohydroxyapatite were used to fabricate three-dimensional porous scaffolds by adopting a combination of solvent casting, particulate leaching, and polymer leaching approaches. The PCL scaffold was subsequently surface modified by chemical bonding of 1,6-hexanediamine to the ester groups of PCL to introduce free NH2 groups. The introduction of NH2 groups as active sites enabled immobilization of biocompatible macromolecule, collagen, on the aminolyzed PCL via a cross-linking agent, glutaraldehyde. The osteoblasts' functions, notably cell adhesion, proliferation, and mineralization, were favorably modulated because of the chemical interaction between Arg-Gly-Asp domains in collagen molecule and integrin receptor in the cell membrane. The study underscores the significance of grafting collagen on PCL-nHA scaffold in modulating cellular activity and biological functions expanding its current use in soft tissue engineering to hard tissue regeneration. PMID:25691223

  12. Removal of Cd(II) and Pb(II) from wastewater by using triethylenetetramine functionalized grafted cellulose acetate-manganese dioxide composite.

    Science.gov (United States)

    Yakout, Amr A; El-Sokkary, Ramadan H; Shreadah, Mohamed A; Abdel Hamid, Omnia G

    2016-09-01

    In this manuscript, we have studied the removal of Cd(II) and Pb(II) ions from aqueous solution by using triethylenetetramine functionalized cellulose acetate grafted with the copolymer-manganese dioxide composite. The novel sorbent cellulose was extracted from the mangrove trees (Avicennia marina) and it was then acetylated and grafted with acrylamide. The sorbent composite was designed to interact simultaneously with higher metal loading by complexation-adsorption process. FT-IR, SEM, EDAX and TGA techniques were employed to characterize the cellulose modified composite. Sorption equilibria were established after 30min and their data were described by Langmuir and Freundlich models. The functionalized hybrid cellulose composite showed maximum adsorption capacity 82.06 and 196.84mgg(-1) for Cd(II) and Pb(II), respectively. The studied metal ions were successfully recovered from real wastewater samples of different matrices. PMID:27185155

  13. Carboxymethyl Cellulose From Kenaf Reinforced Composite Polymer Electrolytes Based 49 % Poly (Methyl Methacrylate)-Grafted Natural Rubber

    International Nuclear Information System (INIS)

    Composite polymer electrolytes based 49 % poly(methyl methacrylate)-grafted natural rubber (MG49) incorporating lithium triflate (LiCF3SO3) were prepared. The study mainly focuses on the ionic conductivity performances and mechanical properties. Prior to that, carboxymethyl cellulose was synthesized from kenaf fiber. The films were characterized by electrochemical impedance (EIS) spectroscopy, linear sweep voltammetry (LSV), universal testing machine and scanning electron microscopy (SEM). The conductivity was found to increase with carboxymethyl cellulose loading. The highest conductivity value achieved was 6.5 x 10-6 Scm-1 upon addition of 6 wt % carboxymethyl cellulose. LSV graph shows the stability of this film was extended to 2.7 V at room temperature. The composition with 6 wt % carboxymethyl cellulose composition showed the highest tensile strength value of 7.9 MPa and 273 MPa of Young's modulus. The morphology of the electrolytes showed a smooth surface of films after addition of salt and filler indicating amorphous phase in electrolytes system. Excellent mechanical properties and good ionic conductivity are obtained, enlightening that the film is suitable for future applications as thin solid polymer electrolytes in lithium batteries. (author)

  14. Bone Grafts

    Science.gov (United States)

    A bone graft transplants bone tissue. Surgeons use bone grafts to repair and rebuild diseased bones in your hips, knees, spine, and sometimes other bones and joints. Grafts can also repair bone loss caused by some ...

  15. Efficacy of guided bone regeneration using composite bone graft and resorbable collagen membrane in Seibert's Class I ridge defects: radiological evaluation.

    Science.gov (United States)

    Saravanan, Pushparajan; Ramakrishnan, T; Ambalavanan, N; Emmadi, Pamela; John, Thomas Libby

    2013-08-01

    The purpose of the study was to evaluate radiologically the efficacy of guided bone regeneration using composite bone graft (autogenous bone graft and anorganic bovine bone graft [Bio-Oss]) along with resorbable collagen membrane (BioMend Extend) in the augmentation of Seibert's class I ridge defects in maxilla. Bone width was evaluated using computerized tomography at day 0 and at day 180 at 2 mm, 4 mm, and 6 mm from the crest. There was a statistically significant increase in bone width between day 0 and day 180 at 2 mm, 4 mm, and 6 mm from the crest. The results of the study demonstrated an increase in bone width of Seibert's class I ridge defects in the maxilla of the study patients. PMID:23964779

  16. Surface modification of nanofibrous polycaprolactone/gelatin composite scaffold by collagen type I grafting for skin tissue engineering

    International Nuclear Information System (INIS)

    In the present study, a tri-polymer polycaprolactone (PCL)/gelatin/collagen type I composite nanofibrous scaffold has been fabricated by electrospinning for skin tissue engineering and wound healing applications. Firstly, PCL/gelatin nanofibrous scaffold was fabricated by electrospinning using a low cost solvent mixture [chloroform/methanol for PCL and acetic acid (80% v/v) for gelatin], and then the nanofibrous PCL/gelatin scaffold was modified by collagen type I (0.2–1.5 wt.%) grafting. Morphology of the collagen type I-modified PCL/gelatin composite scaffold that was analyzed by field emission scanning electron microscopy (FE-SEM), showed that the fiber diameter was increased and pore size was decreased by increasing the concentration of collagen type I. Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated the surface modification of PCL/gelatin scaffold by collagen type I immobilization on the surface of the scaffold. MTT assay demonstrated the viability and high proliferation rate of L929 mouse fibroblast cells on the collagen type I-modified composite scaffold. FE-SEM analysis of cell-scaffold construct illustrated the cell adhesion of L929 mouse fibroblasts on the surface of scaffold. Characteristic cell morphology of L929 was also observed on the nanofiber mesh of the collagen type I-modified scaffold. Above results suggest that the collagen type I-modified PCL/gelatin scaffold was successful in maintaining characteristic shape of fibroblasts, besides good cell proliferation. Therefore, the fibroblast seeded PCL/gelatin/collagen type I composite nanofibrous scaffold might be a potential candidate for wound healing and skin tissue engineering applications. - Highlights: • PCL/gelatin/collagen type I scaffold was fabricated for skin tissue engineering. • PCL/gelatin/collagen type I scaffold showed higher fibroblast growth than PCL/gelatin one. • PCL/gelatin/collagen type I might be one of the ideal scaffold for

  17. Surface modification of nanofibrous polycaprolactone/gelatin composite scaffold by collagen type I grafting for skin tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Sneh [Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee (India); Chou, Chia-Fu [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Dinda, Amit K. [Department of Pathology, All India Institute of Medical Science, New Delhi (India); Potdar, Pravin D. [Department of Molecular Medicine and Biology, Jaslok Hospital and Research Centre, Mumbai (India); Mishra, Narayan C., E-mail: mishrawise@gmail.com [Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee (India)

    2014-01-01

    In the present study, a tri-polymer polycaprolactone (PCL)/gelatin/collagen type I composite nanofibrous scaffold has been fabricated by electrospinning for skin tissue engineering and wound healing applications. Firstly, PCL/gelatin nanofibrous scaffold was fabricated by electrospinning using a low cost solvent mixture [chloroform/methanol for PCL and acetic acid (80% v/v) for gelatin], and then the nanofibrous PCL/gelatin scaffold was modified by collagen type I (0.2–1.5 wt.%) grafting. Morphology of the collagen type I-modified PCL/gelatin composite scaffold that was analyzed by field emission scanning electron microscopy (FE-SEM), showed that the fiber diameter was increased and pore size was decreased by increasing the concentration of collagen type I. Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated the surface modification of PCL/gelatin scaffold by collagen type I immobilization on the surface of the scaffold. MTT assay demonstrated the viability and high proliferation rate of L929 mouse fibroblast cells on the collagen type I-modified composite scaffold. FE-SEM analysis of cell-scaffold construct illustrated the cell adhesion of L929 mouse fibroblasts on the surface of scaffold. Characteristic cell morphology of L929 was also observed on the nanofiber mesh of the collagen type I-modified scaffold. Above results suggest that the collagen type I-modified PCL/gelatin scaffold was successful in maintaining characteristic shape of fibroblasts, besides good cell proliferation. Therefore, the fibroblast seeded PCL/gelatin/collagen type I composite nanofibrous scaffold might be a potential candidate for wound healing and skin tissue engineering applications. - Highlights: • PCL/gelatin/collagen type I scaffold was fabricated for skin tissue engineering. • PCL/gelatin/collagen type I scaffold showed higher fibroblast growth than PCL/gelatin one. • PCL/gelatin/collagen type I might be one of the ideal scaffold for

  18. Cell layer-electrospun mesh composites for coronary artery bypass grafts.

    Science.gov (United States)

    Erndt-Marino, Josh D; Becerra-Bayona, Silvia; McMahon, Rebecca E; Goldstein, Aaron S; Hahn, Mariah S

    2016-09-01

    This work investigates the potential of cell layer-electrospun mesh constructs as coronary artery bypass grafts. These cell-mesh constructs were generated by first culturing a confluent layer of 10T½ smooth muscle progenitor cells on a high strength electrospun mesh with uniaxially aligned fibers. Cell-laden mesh sheets were then wrapped around a cylindrical mandrel such that the mesh fibers were aligned circumferentially. The resulting multi-layered constructs were then cultured for 4 wks in media supplemented with TGF-β1 and ascorbic acid to support 10T½ differentiation toward a smooth muscle cell-like fate as well as to support elastin and collagen production. The underlying hypothesis of this work was that extracellular matrix (ECM) deposited by the cell layers would act as an adhesive agent between the individual mesh layers, providing strength to the construct as well as a source for structural elasticity at low strains. In addition, the structural anisotropy of the mesh would inherently guide desired circumferential cell and ECM alignment. Results demonstrate that the cell-mesh constructs exhibited a J-shaped circumferential stress-strain response similar to that of native coronary artery, while also displaying acceptable tensile strength. Furthermore, associated 10T½ cells and deposited collagen fibers showed a high degree of circumferential alignment. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2200-2209, 2016. PMID:27101019

  19. Synthesis and Characterization of Hydroxyapatite (HA) Composite as Synthetic Bone Graft

    International Nuclear Information System (INIS)

    The preparation and characterization of hydroxyapatite/PVA/PVP/chitosan composite has been done. HA was synthesized by wet method from calcium hydroxide and phosporic acid at controlled pH and temperature. On the other hand, hydroxyapatite/PVA/PVP/ chitosan composite was prepared by gamma radiation at various doses. To evaluate HA produced from the process, several properties such as Ca/P ratio, measurement of functional group either by FTIR or by SEM for analysis of crystalline size are measured. Gel fraction measurement was done to analyze the composite formed by radiation. The results show that the average Ca/P ratio from three batch productions is 1.69. Measurement of fractional group using FTIR shows abs option namely at wave number values of 1035, 603 and 565 cm-1 which indicate phospate group (PO4-3); at 1421 cm-1 which indicates carbonate group (CO3-2); and at 3450 cm-1 which indicates hydroxyl group (OH). These results imply that the wet method produce HA with excellent purity level. Hydroxyapatite/PVA/PVP/chitosan composite irradiated by gamma ray at 5 to 30 kGy doses produce gel fraction in the range of 80 to 90%. This composite with highly gel content is too rigid that has limited in clinical applications. Addition of etanol 5 % to the composite and irradiation at 25 kGy can reduce gel fraction from 90 % to 30 % which more elastic property and easy to be formed as desired. In the mean time, addition of glycerin 6 % could only reduced gel fraction from 90 % to 80 %. Etanol 5 % as scavenger is more effective than glycerin 6 %. (author)

  20. The effects of bone marrow aspirate, bone graft, and collagen composites on fixation of titanium implants

    DEFF Research Database (Denmark)

    Babiker, Hassan; Ding, Ming; Sandri, Monica;

    2012-01-01

    marrow aspirate (BMA) on enhancement of bone implant fixation. Method: Titanium alloy implants were inserted into bilateral femoral condyles of eight skeletally mature sheep, four implants per sheep. The implant had a circumferential gap of 2 mm. The gap was filled with: HA/Collagen; HA......Replacement of extensive local bone loss especially in revision joint arthroplasty and spine fusion is a significant clinical challenge. Allograft and autograft have been considered as gold standards for bone replacement. However, there are several disadvantages such as donor site pain, bacterial...... contamination, and non union as well as the potential risk of disease transmission. Hydroxyapatite and collagen composites (HA/Collagen) have the potential in mimicking and replacing skeletal bones. This study attempted to determine the effects of newly developed HA/Collagen-composites with and without bone...

  1. Poly(lauryl acrylate) and poly(stearyl acrylate) grafted multiwalled carbon nanotubes for polypropylene composites

    DEFF Research Database (Denmark)

    Daugaard, Anders Egede; Jankova Atanasova, Katja; Hvilsted, Søren

    2014-01-01

    , polymerizations of lauryl or stearyl acrylate were performed, resulting in two novel polymer modifications on the MWCNT (poly(lauryl acrylate) or poly(stearyl acrylate)). The method was found to give time dependent loading of polymers as a function of time (up to 38 wt% for both acrylates), and showed a plateau...... were found to be substantially improved, where poly(lauryl acrylate) was found to be the superior surface modification, resulting in a conductive composite....

  2. Impact of graft composition on the systemic inflammatory response after an elective repair of an abdominal aortic aneurysm

    OpenAIRE

    Baek, Jong Kwan; Kwon, Hyunwook; Ko, Gi-Young; Kim, Min Joo; Han, Youngjin; Chung, Young Soo; Park, Hojong; Kwon, Tae-Won; Cho, Yong-Pil

    2014-01-01

    Purpose The present study aimed to evaluate the risk factors and the role of graft material in the development of an acute phase systemic inflammatory response, and the clinical outcome in patients who undergo endovascular aneurysm repair (EVAR) or open surgical repair (OSR) of an abdominal aortic aneurysm (AAA). Methods We retrospectively evaluated the risk factors and the role of graft material in an increased risk of developing systemic inflammatory response syndrome (SIRS), and the clinic...

  3. The effect of Hydroxyapatite/collagen I composites, bone marrow aspirate and bone graft on fixation of bone implants in sheep

    DEFF Research Database (Denmark)

    Babiker, Hassan

      The effect of Hydroxyapatite/collagen I composites, bone marrow aspirate and bone graft on fixation of bone implants IN SHEEP   Ph.D. Student, Hassan Babiker; Associate Professor, Ph.D. Ming Ding; Professor, dr.med., Soren Overgaard. Department of Orthopaedic Surgery, Odense University Hospital......, Odense, Denmark   Background: Hydroxyapatite and collagen composites (HA/coll) have the potential in mimicking and replacing skeletal bones. This study attempted to determine the effect of newly developed HA/coll-composites with and without bone marrow aspirate (BMA) in order to enhance the fixation of...... bone implants.   Materials and Methods: Titanium alloy implants were inserted into bilateral femoral condyles of 8 skeletally mature sheep, four in each sheep. The implant has a circumferential gap of 2 mm. The gap was filled with: HA/coll; HA/coll-BMA; autograft or allograft. Allograft was served as...

  4. One step grafting of iron phthalocyanine containing flexible chains on Fe3O4 nanoparticles towards high performance polymer magnetic composites

    International Nuclear Information System (INIS)

    To develop high-performance inorganic particles/polymer composites, the interfacial interaction and dispersion of inorganic particles are the two essential issues to be considered. Herein, we report an effective approach to graft iron phthalocyanine containing flexible chains (NP-ph) on Fe3O4 nanoparticles (NP-ph@Fe3O4). The hybrids were monodispersed solid nanoparticles with the average diameter of about 250 nm. About 16.8% of the phthalocyanine oligomer was incorporated into the resulting NP-ph@Fe3O4 nanoparticles. The NP-ph@Fe3O4 nanoparticles were subsequently used as the novel filler for preparation of high performance poly(arylene ether nitrile)s (PAEN) composites. The scanning electron microscopy (SEM) investigation showed that the NP-ph@Fe3O4 nanoparticles present better dispersion and interfacial compatibility with PAEN matrix than that of raw Fe3O4, which was further confirmed by rheological study. Consequently, the improved thermal stability and enhanced mechanical properties were obtained from composites using NP-ph@Fe3O4. Vibrating sample magnetometer (VSM) results showed that the prepared PAEN composites exhibited higher saturation magnetization and soft magnetic properties. Meanwhile, the saturation magnetization (Ms) of the PAEN/NP-ph@Fe3O4 composite films increased with the increase of the hybrid nanoparticles loading. Thus, the PAEN/NP-ph@Fe3O4 composite would find potential applications in organic magnetic films fields due to their high thermal stability, excellent flexibility and tunable magnetic properties. - Highlights: • An effective approach to graft CuPc containing flexible chains on Fe. • Effect on the mechanical, thermal and interfacial properties were investigated. • The dispersion state was characterized using parallel-plate rheometry. • The mechanism of interfacial compatibility was clarified

  5. One step grafting of iron phthalocyanine containing flexible chains on Fe{sub 3}O{sub 4} nanoparticles towards high performance polymer magnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Zejun; Zhou, Xuefei; Yang, Xulin; Jia, Kun, E-mail: Jiakun@uestc.edu.cn; Liu, Xiaobo, E-mail: liuxb@uestc.edu.cn

    2015-07-01

    To develop high-performance inorganic particles/polymer composites, the interfacial interaction and dispersion of inorganic particles are the two essential issues to be considered. Herein, we report an effective approach to graft iron phthalocyanine containing flexible chains (NP-ph) on Fe{sub 3}O{sub 4} nanoparticles (NP-ph@Fe{sub 3}O{sub 4}). The hybrids were monodispersed solid nanoparticles with the average diameter of about 250 nm. About 16.8% of the phthalocyanine oligomer was incorporated into the resulting NP-ph@Fe{sub 3}O{sub 4} nanoparticles. The NP-ph@Fe{sub 3}O{sub 4} nanoparticles were subsequently used as the novel filler for preparation of high performance poly(arylene ether nitrile)s (PAEN) composites. The scanning electron microscopy (SEM) investigation showed that the NP-ph@Fe{sub 3}O{sub 4} nanoparticles present better dispersion and interfacial compatibility with PAEN matrix than that of raw Fe{sub 3}O{sub 4}, which was further confirmed by rheological study. Consequently, the improved thermal stability and enhanced mechanical properties were obtained from composites using NP-ph@Fe{sub 3}O{sub 4}. Vibrating sample magnetometer (VSM) results showed that the prepared PAEN composites exhibited higher saturation magnetization and soft magnetic properties. Meanwhile, the saturation magnetization (Ms) of the PAEN/NP-ph@Fe{sub 3}O{sub 4} composite films increased with the increase of the hybrid nanoparticles loading. Thus, the PAEN/NP-ph@Fe{sub 3}O{sub 4} composite would find potential applications in organic magnetic films fields due to their high thermal stability, excellent flexibility and tunable magnetic properties. - Highlights: • An effective approach to graft CuPc containing flexible chains on Fe. • Effect on the mechanical, thermal and interfacial properties were investigated. • The dispersion state was characterized using parallel-plate rheometry. • The mechanism of interfacial compatibility was clarified.

  6. Elemental composition of erythrocytes from coronary artery bypass grafting (CABG) patients with and without type II diabetes mellitus using PIXE analysis

    International Nuclear Information System (INIS)

    A study was conducted on erythrocytes in order to determine the composition and concentration of elements from patients undergoing coronary artery bypass grafting (CABG) surgery with and without type II diabetes. Samples were taken at various timeperiods and analyzed by means of proton induced X-ray emission (PIXE) analysis. Elements detected reliably were P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. In particular, elements worthy of note are S, Cl and Ca, which have strong implications in surgical procedures and aftercare. (author)

  7. Skin Graft

    OpenAIRE

    Ruka Shimizu; Kazuo Kishi

    2012-01-01

    Skin graft is one of the most indispensable techniques in plastic surgery and dermatology. Skin grafts are used in a variety of clinical situations, such as traumatic wounds, defects after oncologic resection, burn reconstruction, scar contracture release, congenital skin deficiencies, hair restoration, vitiligo, and nipple-areola reconstruction. Skin grafts are generally avoided in the management of more complex wounds. Conditions with deep spaces and exposed bones normally require the use o...

  8. Advances in allogenic bone graft processing and usage: preparation and evaluation of chitosan-demineralized cancellous bone powder composite scaffolds as a bone graft substitute

    International Nuclear Information System (INIS)

    Full text: Demineralized bone matrix (DBM) is currently used by surgeons. It usually exists as a lyophilized powder which is difficult to handle and operated. In this study, we try to improve these disadvantages by combining DBM with a biomaterial. It focuses on a natural biodegradable polymer, chitosan, to act as a temporary matrix for bone growth that easily prepare in any size and shape by using tissue engineering knowledge to get a proper temporary matrix. Thus, the development of chitosan-demineralized bone powder composite scaffold is an alternative way. Polymeric scaffold has been demonstrated to have great potential for tissue engineering because the scaffold or three dimension (3D) construct provides the necessary support for cells to proliferate, extracellular matrix deposition and vascularization of neo-tissue. Moreover, chitosan, a natural cationic polymer which its structural is similar to extracellular matrix glycosaminoblycans, is biodegradable, biocompatible, non-antigenic and biofunctional. It can enhance osteoblast cells proliferation and mineral matrix deposition in culture. The first study was to fabricate and analyze composite scaffold composed of either chitosan-demineralized cancellous bone powders or chitosan-demineralized cancellous cartilage bone powders in a ratio 50:50 and 70:30 w/w (chitosan : bone powders) based on physical properties composing of average pore diameter, mechanical integrity and swelling property. Secondly, scaffolds were evaluated in term of biological properties composing of their ability to support neo osteogenesis, including assessments of cell attachment and viability, cell morphology, and the biosynthesis of extracellular matrix. Results indicated that chitosan-demineralized cancellous bone powder composite scaffolds possessing an interconnecting, porous structure could be easily created through a simple freezing and lyophilization process. (Author)

  9. Plant grafting: new mechanisms, evolutionary implications

    OpenAIRE

    Goldschmidt, Eliezer E.

    2014-01-01

    Grafting, an old plant propagation practice, is still widely used with fruit trees and in recent decades also with vegetables. Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant. However, the mechanisms underlying interspecific graft incompatibility are as yet insufficiently understood. Hormonal signals, auxin in particular, are believed to play an important role in the wound healing and vascular regeneration within t...

  10. High Oil-absorptive Composites Prepared from Non-woven Fiber and Sponges with 4-tert- buty1styrene-EPDM-divinylbenzene Graft Polymer

    Institute of Scientific and Technical Information of China (English)

    Zhou Meihua(周美华); Cho Won-Jei

    2001-01-01

    4-tert-butylstyrene-EPDM-divinylbenzene graft terpolymer (PBED) was prepared by graft cross-polymerization in toluene using BPO as an initiator. The gel-PBED and solPBED were isolated from extraction of tetrahydrofuran (THF), and then they were identified by IR spectroscopy. The maximum oil-absorptivity of gel-PBED produced from the optinum reaction conditions was 8 420% but its swelling rate was very low. The highest oil-absorptivity of photocrosslinked sol-PBED film was 5 800%. Although its oil absorbency was not as high as gel-PBED' s, swelling rate was higher than that of gelPBED and was suitable for commercial purpose. After swelling in oil, neither gel PBED nor photocrosslinked sol-PBED film having high oil-absorptivity had sufficient mechanical strength to be taken out of oil wholly. As is known, composite technique is one of the useful methods for reinforcing them. Fibers, sponges and non-woven cloths were used as reinforcers or supporters in this work. Oil-absorptivities and swelling kinetics were evaluated by method ASTM (F726 - 81 ) and an experimental equation. The mechanical properties and the morphologies of some composites were measured by tensile tester and SEM , respectively.

  11. The new reconstruction technique in the treatment of the skin cancers located on the eyelid: Posterior temporalis fascia composite graft

    OpenAIRE

    Copcu, Eray; Sivrioglu, Nazan

    2004-01-01

    Background Difficulty of reconstruction of the eyelids arises from the need to reconstruct different supporting and covering structures in a single operation. Defects in the anterior lamella of the eyelids can be readily repaired with skin grafts or flaps but posterior lamellar reconstruction needs more complex applications. Methods We performed posterior lamellar eyelid reconstruction with posterior parts of the temporalis fascia, since their anatomical and histological features are very sim...

  12. Bone Grafts

    Science.gov (United States)

    ... repair and rebuild diseased bones in your hips, knees, spine, and sometimes other bones and joints. Grafts can also repair bone loss caused by some types of fractures or cancers. Once your body accepts the bone ...

  13. Fibrous polymer-grafted chitosan/clay composite beads as a carrier for immobilization of papain and its usability for mercury elimination.

    Science.gov (United States)

    Metin, Ayşegül Ülkü; Alver, Erol

    2016-07-01

    Papain, which is an industrially important enzyme, has been immobilized on fibrous polymer-modified composite beads, namely poly(methacrylic acid)-grafted chitosan/clay. Characterization studies have been done using FTIR and SEM analysis. Operating parameters such as pH and initial concentration of papain have been varied to obtain the finest papain immobilized polymer-modified composite beads. The immobilization capacity of composite beads has been determined as 34.47 ± 1.18 (n = 3) mg/g. The proteolytic activity of immobilized papain was operated using bovine serum albumin (BSA) and maximum velocity (V max) and Michaelis-Menten constant (Km) values of the free and immobilized enzymes were determined using Lineweaver-Burk and Eadie-Hofstee equations. Usability of papain immobilized polymer-modified composite beads as adsorbents for the elimination of mercury was investigated. The maximum removal capacity of PIPMC beads has been found to be 4.88 ± 0.21 mg Hg/g when the initial metal concentration and weight of polymer-modified composite beads were 50 mg/L and 0.04 g at pH 7, respectively. Mercury removal performance of the papain immobilized polymer-modified composite beads was investigated in conjunction with Cu (II), Zn (II) and Cd (II) ions. The mercury adsorption capacity of papain immobilized polymer-modified composite beads was a slight reduction from 1.15 to 0.89 mg/g in presence of multiple metal salts. PMID:27013506

  14. A Bone Sample Containing a Bone Graft Substitute Analyzed by Correlating Density Information Obtained by X-ray Micro Tomography with Compositional Information Obtained by Raman Microscopy

    Directory of Open Access Journals (Sweden)

    Johann Charwat-Pessler

    2015-06-01

    Full Text Available The ability of bone graft substitutes to promote new bone formation has been increasingly used in the medical field to repair skeletal defects or to replace missing bone in a broad range of applications in dentistry and orthopedics. A common way to assess such materials is via micro computed tomography (µ-CT, through the density information content provided by the absorption of X-rays. Information on the chemical composition of a material can be obtained via Raman spectroscopy. By investigating a bone sample from miniature pigs containing the bone graft substitute Bio Oss®, we pursued the target of assessing to what extent the density information gained by µ-CT imaging matches the chemical information content provided by Raman spectroscopic imaging. Raman images and Raman correlation maps of the investigated sample were used in order to generate a Raman based segmented image by means of an agglomerative, hierarchical cluster analysis. The resulting segments, showing chemically related areas, were subsequently compared with the µ-CT image by means of a one-way ANOVA. We found out that to a certain extent typical gray-level values (and the related histograms in the µ-CT image can be reliably related to specific segments within the image resulting from the cluster analysis.

  15. Fabrication of small-diameter vascular scaffolds by heparin-bonded P(LLA-CL composite nanofibers to improve graft patency

    Directory of Open Access Journals (Sweden)

    Wang S

    2013-06-01

    Full Text Available Sheng Wang,1,* Xiu M Mo,2,* Bo J Jiang,1 Cheng J Gao,1 Hong S Wang,2 Yu G Zhuang,1 Li J Qiu21Department of Emergency and Critical Care Medicine, Shanghai Tenth People’s Hospital, Tongji University, Shanghai, People's Republic of China; 2State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai, People’s Republic of China *These authors contributed equally to this workAbstract: The poor patency rate following small-diameter vascular grafting remains a major hurdle for the widespread clinical application of artificial blood vessels to date. Our previous studies found that electrospun poly(L-lactide-co-epsilon-caprolactone (P[LLA-CL] nanofibers facilitated the attachment and growth of endothelial cells (EC, and heparin incorporated into P(LLA-CL nanofibers was able to release in a controlled manner. Hence, we hypothesized that heparin-bonded P(LLA-CL vascular scaffolds with autologous EC pre-endothelialization could significantly promote the graft patency rate. To construct a small-diameter vascular scaffold, the inner layer was fabricated by heparin-bonded P(LLA-CL nanofibers through coaxial electrospinning, while the outer layer was woven by pure P(LLA-CL nanofibers. Except dynamic compliance (5.4 ± 1.7 versus 12.8 ± 2.4 × 10-4/mmHg, P < 0.05, maximal tensile strength, burst pressure, and suture retention of the composite, scaffolds were comparable to those of canine femoral arteries. In vitro studies indicated that the scaffolds can continuously release heparin for at least 12 weeks and obtain desirable endothelialization through dynamic incubation, which was confirmed by EC viability and proliferation assay and scanning electronic microscopy. Furthermore, in vivo studies demonstrated that pre-endothelialization by autologous ECs provided a better effect on graft patency rate in comparison with heparin loading, and the united application of pre-endothelialization and heparin loading

  16. Electrospun composite nanofiber membrane of poly(l-lactide) and surface grafted chitin whiskers: Fabrication, mechanical properties and cytocompatibility.

    Science.gov (United States)

    Liu, Hua; Liu, Wenjun; Luo, Binghong; Wen, Wei; Liu, Mingxian; Wang, Xiaoying; Zhou, Changren

    2016-08-20

    To improve both the mechanical properties and cytocompatibility of poly(l-lactide) (PLLA), rod-like chitin whiskers (CHWs) were prepared, and subsequently surface modified with l-lactide to obtain grafted CHWs (g-CHWs). Then, CHWs and g-CHWs were further introduced into PLLA matrix to fabricate CHWs/PLLA and g-CHWs/PLLA nanofiber membranes by electrospinning technique. Morphologies and properties of the CHWs and g-CHWs were characterized. The surface-grafted PLLA chains played an important role in improving interfacial interaction between the whiskers and PLLA matrix. The g-CHWs dispersed more uniformly in matrix than CHWs, and the as-prepared g-CHWs/PLLA nanofiber membrane showed relative smooth and uniform fiber. As a result, the tensile strength and modulus of the g-CHWs/PLLA nanofiber membrane were obviously superior to those of the pure PLLA and CHWs/PLLA nanofiber membranes. Cells culture results indicated that g-CHWs/PLLA nanofiber membrane is more effectively in promoting MC3T3-E1 cells adhesion, spreading and proliferation than pure PLLA and CHWs/PLLA nanofiber membrane. PMID:27178927

  17. Radiation grafting on natural films

    Science.gov (United States)

    Lacroix, M.; Khan, R.; Senna, M.; Sharmin, N.; Salmieri, S.; Safrany, A.

    2014-01-01

    Different methods of polymer grafting using gamma irradiation are reported in the present study for the preparation of newly functionalized biodegradable films, and some important properties related to their mechanical and barrier properties are described. Biodegradable films composed of zein and poly(vinyl alcohol) (PVA) were gamma-irradiated in presence of different ratios of acrylic acid (AAc) monomer for compatibilization purpose. Resulting grafted films (zein/PVA-g-AAc) had their puncture strength (PS=37-40 N mm-1) and puncture deformation (PD=6.5-9.8 mm) improved for 30% and 50% PVA in blend, with 5% AAc under 20 kGy. Methylcellulose (MC)-based films were irradiated in the presence of 2-hydroxyethyl methacrylate (HEMA) or silane, in order to determine the effect of monomer grafting on the mechanical properties of films. It was found that grafted films (MC-g-HEMA and MC-g-silane) using 35% monomer performed higher mechanical properties with PS values of 282-296 N mm-1 and PD of 5.0-5.5 mm under 10 kGy. Compatibilized polycaprolactone (PCL)/chitosan composites were developed via grafting silane in chitosan films. Resulting trilayer grafted composite film (PCL/chitosan-g-silane/PCL) presented superior tensile strength (TS=22 MPa) via possible improvement of interfacial adhesion (PCL/chitosan) when using 25% silane under 10 kGy. Finally, MC-based films containing crystalline nanocellulose (CNC) as a filling agent were prepared and irradiated in presence of trimethylolpropane trimethacrylate (TMPTMA) as a grafted plasticizer. Grafted films (MC-g-TMPTMA) presented superior mechanical properties with a TS of 47.9 MPa and a tensile modulus (TM) of 1792 MPa, possibly due to high yield formation of radicals to promote TMPTMA grafting during irradiation. The addition of CNC led to an additional improvement of the barrier properties, with a significant 25% reduction of water vapor permeability (WVP) of grafted films.

  18. Plant grafting: new mechanisms, evolutionary implications.

    Science.gov (United States)

    Goldschmidt, Eliezer E

    2014-01-01

    Grafting, an old plant propagation practice, is still widely used with fruit trees and in recent decades also with vegetables. Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant. However, the mechanisms underlying interspecific graft incompatibility are as yet insufficiently understood. Hormonal signals, auxin in particular, are believed to play an important role in the wound healing and vascular regeneration within the graft union zone. Incomplete and convoluted vascular connections impede the vital upward and downward whole plant transfer routes. Long-distance protein, mRNA and small RNA graft-transmissible signals currently emerge as novel mechanisms which regulate nutritional and developmental root/top relations and may play a pivotal role in grafting physiology. Grafting also has significant pathogenic projections. On one hand, stock to scion mechanical contact enables the spread of diseases, even without a complete graft union. But, on the other hand, grafting onto resistant rootstocks serves as a principal tool in the management of fruit tree plagues and vegetable soil-borne diseases. The 'graft hybrid' historic controversy has not yet been resolved. Recent evidence suggests that epigenetic modification of DNA-methylation patterns may account for certain graft-transformation phenomena. Root grafting is a wide spread natural phenomenon; both intraspecific and interspecific root grafts have been recorded. Root grafts have an evolutionary role in the survival of storm-hit forest stands as well as in the spread of devastating diseases. A more fundamental evolutionary role is hinted by recent findings that demonstrate plastid and nuclear genome transfer between distinct Nicotiana species in the graft union zone, within a tissue culture system. This has led to the formation of alloploid cells that, under laboratory conditions, gave rise to a novel, alloploid Nicotiana species, indicating

  19. Plant grafting: new mechanisms, evolutionary implications

    Directory of Open Access Journals (Sweden)

    Eliezer E Goldschmidt

    2014-12-01

    Full Text Available Grafting, an old plant propagation practice, is still widely used with fruit trees and in recent decades also with vegetables. Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant. However, the mechanisms underlying interspecific graft incompatibility are as yet insufficiently understood. Hormonal signals, auxin in particular, are believed to play an important role in the wound healing and vascular regeneration within the graft union zone. Long-distance protein, mRNA and small RNA graft-transmissible signals currently emerge as novel mechanisms which regulate nutritional and developmental root/top relations and may play a pivotal role in grafting physiology. Grafting also has significant pathogenic projections. On one hand, stock to scion mechanical contact enables the spread of diseases, even without a complete graft union. But, on the other hand, grafting onto resistant rootstocks serves as a principal tool in the management of fruit tree plagues and vegetable soil-borne diseases. The ‘graft hybrid’ historic controversy has not yet been resolved. Recent evidence suggests that epigenetic modification of DNA-methylation patterns may account for certain graft-transformation phenomena. Root grafting is a wide spread natural phenomenon; both intraspecific and interspecific root grafts have been recorded. Root grafts have an evolutionary role in the survival of storm-hit forest stands as well as in the spread of devastating diseases. A more fundamental evolutionary role is hinted by recent findings that demonstrate plastid and nuclear genome transfer between distinct Nicotiana species in the graft union zone, within a tissue culture system. This has led to the formation of alloploid cells that, under laboratory conditions, gave rise to a novel, alloploid Nicotiana species, indicating that natural grafts may play a role in plant speciation. under certain circumstances.

  20. Influence of the electronic distribution of polymers in the spatial conformation of polymer grafted carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Garate, H. [Universidad de Buenos Aires, FCEyN, Depto. de Fisica IFIBA-CONICET LPyMC, Pabellon I, Buenos Aires 1428 (Argentina); Universidad de Buenos Aires, FCEyN, Depto. de Quimica Organica, (CIHIDECAR-CONICET) Buenos Aires 1428 (Argentina); De Falco, A. [Universidad de Buenos Aires, FCEyN, Depto. de Fisica IFIBA-CONICET LPyMC, Pabellon I, Buenos Aires 1428 (Argentina); Moreno, M.S. [Centro Atomico Bariloche, 8400 S.C. de Bariloche (Argentina); Fascio, M.L. [Universidad de Buenos Aires, FCEyN, Depto. de Quimica Organica, (CIHIDECAR-CONICET) Buenos Aires 1428 (Argentina); Goyanes, S. [Universidad de Buenos Aires, FCEyN, Depto. de Fisica IFIBA-CONICET LPyMC, Pabellon I, Buenos Aires 1428 (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); D' Accorso, N.B., E-mail: norma@qo.fcen.uba.ar [Universidad de Buenos Aires, FCEyN, Depto. de Quimica Organica, (CIHIDECAR-CONICET) Buenos Aires 1428 (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)

    2012-08-15

    In this work we report the covalent functionalization of multiwalled carbon nanotubes (MWCNTs) with polyacrylonitrile (PAN) and polyvinylpyridine (PVP) by the graft from method. Differences in the electronic distribution of both polymers resulted in different interaction between polymers and the nanotubes. It was found that PVP chains wrapped the nanotubes while nanotubes functionalized with PAN presented PAN chains forming amorphous entanglements on the nanoscale linked to the MWCNTs. Differences in the conformation between both polymers and the MWCNTs can be attributed to interactions between the aromatic groups in PVP and the MWCNTs through {pi}-{pi} stacking. The absence of aromatic groups in the case of the PAN chains favours the interaction between them. The functionalization efficiency was characterized using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and UV-vis spectroscopy, while morphological changes were characterized by high resolution transmission electron microscopy.

  1. Novel additives in radiation polymerisation processes. Significance of molecular weight data in their application to grafting, curing and composite formation

    International Nuclear Information System (INIS)

    The role of additives in accelerating rates of reaction has been investigated in the following related radiation polymerisation processes, i.e simple homopolymerisation, grafting, WPC formation and curing. Additives used include mineral acid, polyfunctional monomers, urea and thermal and photochemical initiators. Molecular weight analysis carried out on the polymers formed in the presence of the additives indicate that both chemical and physical processes are involved in the mechanism of the polymerisation reaction. Chemical processes (free radicals) lead to an enhancement in initial rate of polymerisation whilst the physical parameter involves partitioning of reagents during reaction. Both chemical and physical processes are shown to act in concert to influence both polymer yield and properties

  2. Acid-resistant calcium silicate-based composite implants with high-strength as load-bearing bone graft substitutes and fracture fixation devices.

    Science.gov (United States)

    Wei, Chung-Kai; Ding, Shinn-Jyh

    2016-09-01

    To achieve the excellent mechanical properties of biodegradable materials used for cortical bone graft substitutes and fracture fixation devices remains a challenge. To this end, the biomimetic calcium silicate/gelatin/chitosan oligosaccharide composite implants were developed, with an aim of achieving high strength, controlled degradation, and superior osteogenic activity. The work focused on the effect of gelatin on mechanical properties of the composites under four different kinds of mechanical stresses including compression, tensile, bending, and impact. The evaluation of in vitro degradability and fatigue at two simulated body fluid (SBF) of pH 7.4 and 5.0 was also performed, in which the pH 5.0 condition simulated clinical conditions caused by bacterial induced local metabolic acidosis or tissue inflammation. In addition, human mesenchymal stem cells (hMSCs) were sued to examine osteogenic activity. Experimental results showed that the appropriate amount of gelatin positively contributed to failure enhancement in compressive and impact modes. The 10wt% gelatin-containing composite exhibits the maximum value of the compressive strength (166.1MPa), which is within the reported compressive strength for cortical bone. The stability of the bone implants was apparently affected by the in vitro fatigue, but not by the initial pH environments (7.4 or 5.0). The gelatin not only greatly enhanced the degradation of the composite when soaked in the dynamic SBF solution, but effectively promoted attachment, proliferation, differentiation, and formation of mineralization of hMSCs. The 10wt%-gelatin composite with high initial strength may be a potential implant candidate for cortical bone repair and fracture fixation applications. PMID:27254281

  3. A preliminary study on the dynamic-mechanical behaviour of compression moulded polypropylene/carbon fiber composites interfacially modified by a succinic anhydride grafted atactic polypropylene from polymer wastes

    Science.gov (United States)

    García-Martínez, Jesús María; Areso, Susana; Collar, Emilia P.

    2016-05-01

    Present communication is devoted to the study of the effect of a novel interfacial agent in polypropylene/carbon fibre composites. The interfacial agent used is a succinic anhydride grafted atactic polypropylene containing both succinic bridges and side grafts (aPP-SASA) and with 5.6% (5.6.10-4g/mol) of grafting content obtained at the GIP labs. The study considers the study dynamic-mechanical behaviour with temperature at a frequency of 1 hz to ascertain the differences in the interfacial activity. The samples were compression molded in order to isolate as far as possible the effect of the solely aPP-SASA in absence of those synergetic effects due to the preferential orientation of the fibres.

  4. Self-Assembly of Polyethylene Glycol-Grafted Carbon Nanotube/Sulfur Composite with Nest-like Structure for High-Performance Lithium-Sulfur Batteries.

    Science.gov (United States)

    Li, Han; Sun, Liping; Wang, Gengchao

    2016-03-01

    The novel polyethylene glycol-grafted multiwalled carbon nanotube/sulfur (PEG-CNT/S) composite cathodes with nest-like structure are fabricated through a facile combination process of liquid phase deposition and self-assembly, which consist of the active material core of sulfur particle and the conductive shell of PEG-CNT network. The unique architecture not only provides a short and rapid charge transfer pathway to improve the reaction kinetics but also alleviates the volume expansion of sulfur during lithiation and minimizes the diffusion of intermediate polysulfides. Such an encouraging electrochemical environment ensures the excellent rate capability and high cycle stability. As a result, the as-prepared PEG-CNT/S composite with sulfur content of 75.9 wt % delivers an initial discharge capacity of 1191 and 897 mAh g(-1) after 200 cycles at 0.2 C with an average Coulombic efficiency of 99.5%. Even at a high rate of 2 C, an appreciable capacity of 723 mAh g(-1) can still be obtained. PMID:26890092

  5. Synthesis and characterization of chitosan-graft-poly(acrylic acid)/rice husk ash hydrogels composites; Sintese e caracterizacao de hidrogeis compositos de cinza da casca de arroz e quitosana enxertada com poli(acido acrilico)

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Francisco H.A. [Universidade Estadual Vale do Acarau - UVA, Sobral, CE (Brazil); Lopes, Gabriel V.; Pereira, Antonio G.B.; Fajardo, Andre R.; Muniz, Edvani C. [Universidade Estadual de Maringa - UEM, PR (Brazil)

    2011-07-01

    According to environmental concerns, super absorbent hydrogel composites were synthesized based on rice husk ash (RHA), an industrial waste, and Chitosan-graft-poly(acrylic acid). The WAXS and FTIR data confirmed the syntheses of hydrogel composites. The effect of crystalline or amorphous RHA on water uptake was investigated. It was found that the RHA in crystalline form induces higher water capacity (W{sub eq}) of composites hydrogels due to the fact that the intra-interactions among silanol groups on RHA make available new sites in the polymer matrix, which could interact to water. (author)

  6. Stent graft placement for dysfunctional arteriovenous grafts

    International Nuclear Information System (INIS)

    This study aimed to evaluate the usefulness and outcomes of stent graft use in dysfunctional arteriovenous grafts. Eleven patients who underwent stent graft placement for a dysfunctional hemodialysis graft were included in this retrospective study. Expanded polytetrafluoroethylene covered stent grafts were placed at the venous anastomosis site in case of pseudoaneurysm, venous laceration, elastic recoil or residual restenosis despite the repeated angioplasty. The patency of the arteriovenous graft was evaluated using Kaplan-Meier analysis. Primary and secondary mean patency was 363 days and 741 days. Primary patency at 3, 6, and 12 months was 82%, 73%, and 32%, respectively. Secondary patency at the 3, 6, 12, 24, and 36 months was improved to 91%, 82%, 82%, 50%, and 25%, respectively. Fractures of the stent graft were observed in 2 patients, but had no effect on the patency. Stent graft placement in dysfunctional arteriovenous graft is useful and effective in prolonging graft patency

  7. Stent graft placement for dysfunctional arteriovenous grafts

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Gyeong Sik [Dept. of Radiology, CHA Bundang Medical Center, College of Medicine, CHA University, Seongnam (Korea, Republic of); Shin, Byung Seok; Ohm, Joon Young; Ahn, Moon Sang [Chungnam National University Hospital, Daejeon (Korea, Republic of)

    2015-07-15

    This study aimed to evaluate the usefulness and outcomes of stent graft use in dysfunctional arteriovenous grafts. Eleven patients who underwent stent graft placement for a dysfunctional hemodialysis graft were included in this retrospective study. Expanded polytetrafluoroethylene covered stent grafts were placed at the venous anastomosis site in case of pseudoaneurysm, venous laceration, elastic recoil or residual restenosis despite the repeated angioplasty. The patency of the arteriovenous graft was evaluated using Kaplan-Meier analysis. Primary and secondary mean patency was 363 days and 741 days. Primary patency at 3, 6, and 12 months was 82%, 73%, and 32%, respectively. Secondary patency at the 3, 6, 12, 24, and 36 months was improved to 91%, 82%, 82%, 50%, and 25%, respectively. Fractures of the stent graft were observed in 2 patients, but had no effect on the patency. Stent graft placement in dysfunctional arteriovenous graft is useful and effective in prolonging graft patency.

  8. Surgery of the aortic root: should we go for the valve-sparing root reconstruction or the composite graft-valve replacement is still the first choice of treatment for these patients?

    Directory of Open Access Journals (Sweden)

    Fernando de Azevedo Lamana

    2015-09-01

    Full Text Available AbstractObjective:To compare the results of the root reconstruction with the aortic valve-sparing operation versus composite graftvalve replacement.Methods:From January 2002 to October 2013, 324 patients underwent aortic root reconstruction. They were 263 composite graft-valve replacement and 61 aortic valve-sparing operation (43 reimplantation and 18 remodeling. Twenty-six percent of the patients were NYHA functional class III and IV; 9.6% had Marfan syndrome, and 12% had bicuspid aortic valve. There was a predominance of aneurysms over dissections (81% vs. 19%, with 7% being acute dissections. The complete follow-up of 100% of the patients was performed with median follow-up time of 902 days for patients undergoing composite graft-valve replacement and 1492 for those undergoing aortic valve-sparing operation.Results:In-hospital mortality was 6.7% and 4.9%, respectively for composite graft-valve replacement and aortic valve-sparing operation (ns. During the late follow-up period, there was 0% moderate and 15.4% severe aortic regurgitation, and NYHA functional class I and II were 89.4% and 94%, respectively for composite graft-valve replacement and aortic valve-sparing operation (ns. Root reconstruction with aortic valve-sparing operation showed lower late mortality (P=0.001 and lower bleeding complications (P=0.006. There was no difference for thromboembolism, endocarditis, and need of reoperation.Conclusion:The aortic root reconstruction with preservation of the valve should be the operation being performed for presenting lower late mortality and survival free of bleeding events.

  9. Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE Addition

    Directory of Open Access Journals (Sweden)

    Yun Lu

    2013-06-01

    Full Text Available This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs. The maximum values of the specific tensile and flexural strengths are achieved at a MAPE content of 5%–8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition.

  10. Aminosilane-Grafted Zirconia-Titiania-Silica Nanoparticles/Torlon Hollow Fiber Composites for CO2 Capture.

    Science.gov (United States)

    Rownaghi, Ali A; Kant, Amit; Li, Xin; Thakkar, Harshul; Hajari, Amit; He, Yingxin; Brennan, Patrick J; Hosseini, Hooman; Koros, William J; Rezaei, Fateme

    2016-05-23

    In this work, the development of novel binary and ternary oxide/Torlon hollow fiber composites comprising zirconia, titania, and silica as amine supports was demonstrated. The resulting binary (Zr-Si/PAI-HF, Ti-Si/PAI-HF) and ternary (Zr-Ti-Si/PAI-HF) composites were then functionalized with monoamine-, diamine-, and triamine-substituted trialkoxysilanes and were evaluated in CO2 capture. Although the introduction of both Zr and Ti improved the CO2 adsorption capacity relative to that with Si/PAI-HF sorbents, zirconia was found to have a more favorable effect on the CO2 adsorption performance than titania, as previously demonstrated for amine sorbents in the powder form. The Zr-Ti-Si/PAI-HF sample with an oxide content of 20 wt % was found to exhibit a relatively high CO2 capacity, that is, 1.90 mmol g(-1) at atmospheric pressure under dry conditions, owing to more favorable synergy between the metal oxides and CO2 . The ternary fiber sorbent showed improved sorption kinetics and long-term stability in cyclic adsorption/desorption runs. PMID:27076214

  11. Radiation grafting on natural films

    International Nuclear Information System (INIS)

    Different methods of polymer grafting using gamma irradiation are reported in the present study for the preparation of newly functionalized biodegradable films, and some important properties related to their mechanical and barrier properties are described. Biodegradable films composed of zein and poly(vinyl alcohol) (PVA) were gamma-irradiated in presence of different ratios of acrylic acid (AAc) monomer for compatibilization purpose. Resulting grafted films (zein/PVA-g-AAc) had their puncture strength (PS=37–40 N mm−1) and puncture deformation (PD=6.5–9.8 mm) improved for 30% and 50% PVA in blend, with 5% AAc under 20 kGy. Methylcellulose (MC)-based films were irradiated in the presence of 2-hydroxyethyl methacrylate (HEMA) or silane, in order to determine the effect of monomer grafting on the mechanical properties of films. It was found that grafted films (MC-g-HEMA and MC-g-silane) using 35% monomer performed higher mechanical properties with PS values of 282–296 N mm−1 and PD of 5.0–5.5 mm under 10 kGy. Compatibilized polycaprolactone (PCL)/chitosan composites were developed via grafting silane in chitosan films. Resulting trilayer grafted composite film (PCL/chitosan-g-silane/PCL) presented superior tensile strength (TS=22 MPa) via possible improvement of interfacial adhesion (PCL/chitosan) when using 25% silane under 10 kGy. Finally, MC-based films containing crystalline nanocellulose (CNC) as a filling agent were prepared and irradiated in presence of trimethylolpropane trimethacrylate (TMPTMA) as a grafted plasticizer. Grafted films (MC-g-TMPTMA) presented superior mechanical properties with a TS of 47.9 MPa and a tensile modulus (TM) of 1792 MPa, possibly due to high yield formation of radicals to promote TMPTMA grafting during irradiation. The addition of CNC led to an additional improvement of the barrier properties, with a significant 25% reduction of water vapor permeability (WVP) of grafted films. - Highlights: • Irradiation of zein

  12. Bone grafting: An overview

    Directory of Open Access Journals (Sweden)

    D. O. Joshi

    2010-08-01

    Full Text Available Bone grafting is the process by which bone is transferred from a source (donor to site (recipient. Due to trauma from accidents by speedy vehicles, falling down from height or gunshot injury particularly in human being, acquired or developmental diseases like rickets, congenital defects like abnormal bone development, wearing out because of age and overuse; lead to bone loss and to replace the loss we need the bone grafting. Osteogenesis, osteoinduction, osteoconduction, mechanical supports are the four basic mechanisms of bone graft. Bone graft can be harvested from the iliac crest, proximal tibia, proximal humerus, proximal femur, ribs and sternum. An ideal bone graft material is biologically inert, source of osteogenic, act as a mechanical support, readily available, easily adaptable in terms of size, shape, length and replaced by the host bone. Except blood, bone is grafted with greater frequency. Bone graft indicated for variety of orthopedic abnormalities, comminuted fractures, delayed unions, non-unions, arthrodesis and osteomyelitis. Bone graft can be harvested from the iliac crest, proximal tibia, proximal humerus, proximal femur, ribs and sternum. By adopting different procedure of graft preservation its antigenicity can be minimized. The concept of bone banking for obtaining bone grafts and implants is very useful for clinical application. Absolute stability require for successful incorporation. Ideal bone graft must possess osteogenic, osteoinductive and osteocon-ductive properties. Cancellous bone graft is superior to cortical bone graft. Usually autologous cancellous bone graft are used as fresh grafts where as allografts are employed as an alloimplant. None of the available type of bone grafts possesses all these properties therefore, a single type of graft cannot be recomm-ended for all types of orthopedic abnormalities. Bone grafts and implants can be selected as per clinical problems, the equipments available and preference of

  13. Antimicrobial Graft Copolymer Gels.

    Science.gov (United States)

    Harvey, Amanda C; Madsen, Jeppe; Douglas, C W Ian; MacNeil, Sheila; Armes, Steven P

    2016-08-01

    In view of the growing worldwide rise in microbial resistance, there is considerable interest in designing new antimicrobial copolymers. The aim of the current study was to investigate the relationship between antimicrobial activity and copolymer composition/architecture to gain a better understanding of their mechanism of action. Specifically, the antibacterial activity of several copolymers based on 2-(methacryloyloxy)ethyl phosphorylcholine [MPC] and 2-hydroxypropyl methacrylate (HPMA) toward Staphylococcus aureus was examined. Both block and graft copolymers were synthesized using either atom transfer radical polymerization or reversible addition-fragmentation chain transfer polymerization and characterized via (1)H NMR, gel permeation chromatography, rheology, and surface tensiometry. Antimicrobial activity was assessed using a range of well-known assays, including direct contact, live/dead staining, and the release of lactate dehydrogenase (LDH), while transmission electron microscopy was used to study the morphology of the bacteria before and after the addition of various copolymers. As expected, PMPC homopolymer was biocompatible but possessed no discernible antimicrobial activity. PMPC-based graft copolymers comprising PHPMA side chains (i.e. PMPC-g-PHPMA) significantly reduced both bacterial growth and viability. In contrast, a PMPC-PHPMA diblock copolymer comprising a PMPC stabilizer block and a hydrophobic core-forming PHPMA block did not exhibit any antimicrobial activity, although it did form a biocompatible worm gel. Surface tensiometry studies and LDH release assays suggest that the PMPC-g-PHPMA graft copolymer exhibits surfactant-like activity. Thus, the observed antimicrobial activity is likely to be the result of the weakly hydrophobic PHPMA chains penetrating (and hence rupturing) the bacterial membrane. PMID:27409712

  14. Acrylique acid grafted polyolefines. Thermoadhesive applications

    International Nuclear Information System (INIS)

    Radiochemical grafting of polyolefines by peroxidation has been industrialized in France for about 10 years by irradiation of these polymers with an electron accelerator and then treated by acrylic acid. Products obtained show a high adhesivity on metallic surfaces above their melting point. The main application of acrylic acid grafted high density polyethylene is composite film with aluminum foil for thermosealing of plastic bottle caps of sterilized milk. Acrylic acid grafted polypropylene is used in suspension in a volatile liquid for aluminum foil coating satisfying food packaging regulations

  15. Viscoelastic and photo-actuation studies of composites based on polystyrene-grafted carbon nanotubes and styrene-b-isoprene-b-styrene block copolymer

    Czech Academy of Sciences Publication Activity Database

    Ilčíková, M.; Mrlík, M.; Sedláček, T.; Chorvát, D.; Krupa, I.; Šlouf, Miroslav; Koynov, K.; Mosnáček, J.

    2014-01-01

    Roč. 55, č. 1 (2014), s. 211-218. ISSN 0032-3861 R&D Projects: GA TA ČR TE01020118 Institutional support: RVO:61389013 Keywords : thermoplastic elastomers * grafting from surface * smart materials Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.562, year: 2014

  16. Grafting and curing

    International Nuclear Information System (INIS)

    Progress in radiation grafting and curing is briefly reviewed. The two processes are shown to be mechanistically related. The parameters influencing yields are examined particularly for grafting. For ionising radiation grafting systems (EB and gamma ray) these include solvents, substrate and monomer structure, dose and dose-rate, temperature and more recently role of additives. In addition, for UV grafting, the significance of photoinitiators is discussed. Current applications of radiation grafting and curing are outlined. The recent development of photoinitiator free grafting and curing is examined as well as the potential for the new excimer laser sources. The future application of both grafting and curing is considered, especially the significance of the occurrence of concurrent grafting during cure and its relevance in environmental considerations

  17. Butterfly cartilage graft versus fat graft myringoplasty

    Directory of Open Access Journals (Sweden)

    Sonika Kanotra

    2016-01-01

    Full Text Available Aim: The aim of the study was to compare the graft take up rates of two minimally invasive techniques of butterfly cartilage graft (BCG and fat graft myringoplasty (FGM. Materials and Methods: Two groups of 30 patients each with small dry central perforations of the tympanic membrane (T.M. were randomly subjected to either of the two techniques of myringoplasty. Statistical Analysis Used: The results were compared using the Chi-square test. A value of <0.05 was taken as statistically significant. Results: The graft take up rate was 93.3% with BCG and 83.3% with fat graft. Conclusions: The BCG scores over FGM in small perforations of the T.M.

  18. Bone grafts in dentistry

    OpenAIRE

    Prasanna Kumar; Belliappa Vinitha; Ghousia Fathima

    2013-01-01

    Bone grafts are used as a filler and scaffold to facilitate bone formation and promote wound healing. These grafts are bioresorbable and have no antigen-antibody reaction. These bone grafts act as a mineral reservoir which induces new bone formation.

  19. Bone grafts in dentistry

    Directory of Open Access Journals (Sweden)

    Prasanna Kumar

    2013-01-01

    Full Text Available Bone grafts are used as a filler and scaffold to facilitate bone formation and promote wound healing. These grafts are bioresorbable and have no antigen-antibody reaction. These bone grafts act as a mineral reservoir which induces new bone formation.

  20. Electrolytic membrane formation of fluoroalkyl polymer using a UV-radiation-based grafting technique and sulfonation

    Energy Technology Data Exchange (ETDEWEB)

    Shironita, Sayoko; Mizoguchi, Satoko; Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Niigata (Japan)

    2011-03-15

    A sulfonated fluoroalkyl graft polymer (FGP) membrane was prepared as a polymer electrolyte. First, the FGP membrane was grafted with styrene under UV irradiation. The grafted FGP was then sulfonated to functionalize it for proton conductivity. The grafting degree of the membrane increased with increasing grafting time during UV irradiation. The proton conductivity of the membrane increased with increasing grafting degree. The swelling ratio was independent of the grafting time, however, the water uptake increased with increasing grafting degree. Based on these results, it was found that the UV-initiated styrene grafting occurred along the membrane thickness direction. Moreover, the membrane was embedded within the glass fibers of the composite. This composite electrolytic membrane had 1.15 times the proton conductivity of a Nafion 117 membrane.

  1. Carbon nanotube grafted with polyalcohol and its influence on the thermal conductivity of phase change material

    International Nuclear Information System (INIS)

    Highlights: • CNTs are grafted with polyhydric alcohols. • The grafted CNTs are well dispersed. • The graft ratio of CNTs-C8, CNTs-C14 and CNTs-C18 is 11%, 32% and 38%. • The thermal conductivities of CNTs/paraffin are increased through graft treatment. • The carbon number of polyalcohol has influence on thermal conductivity. - Abstract: Carbon nanotubes (CNTs) were grafted with polyhydric alcohols (octanol, tetradecyl alchohol and stearyl alcohol) after acidification. The composite phase change materials (PCMs) were prepared with grafted CNTs and paraffin. The grafted CNTs were characterized with Transmission Electron Micrograph (TEM), X-ray Diffractometer (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric analyzer (TG). Hot disk method was employed to measure the thermal conductivity of composite PCMs. The results showed that polyhydric alcohols were grafted onto CNTs. The graft ratio was 38% for the CNTs grafted with stearyl alcohol. The grafted CNTs were shorter than CNTs and the dispersibility of grafted CNTs was better than that of CNTs. The thermal conductivity of grafted CNTs/paraffin composite PCMs was higher than that of pristine CNTs/paraffin composite PCMs

  2. Ruptured saphenous vein graft pseudoaneurysm successfully treated with covered stents.

    Science.gov (United States)

    Yonezu, Keisuke; Funayama, Hiroshi; Katayama, Takuji; Yamaguchi, Atsushi; Ako, Junya; Momomura, Shin-Ichi

    2016-04-01

    Saphenous vein graft (SVG) pseudoaneurysms are rare complications following coronary bypass graft surgery. A 46-year-old man presented with streptococcal infectious endocarditis and needed sequential operations for aortic root reconstruction. Shortly after the surgeries, a composite SVG on the right coronary artery developed a ruptured pseudoaneurysm, which was successfully treated using covered stents. PMID:25917780

  3. Preparation and Properties of Polypropylene Grafted Maleic Anhydride/Surface Modiifed Kaolin Composites%PP-g-MAH/改性高岭土复合材料的制备与性能

    Institute of Scientific and Technical Information of China (English)

    张作才; 夏玥; 石晶晶; 马宁; 蔡芳昌; 蒋涛

    2014-01-01

    利用γ-氨丙基三乙氧基硅烷偶联剂(KH550)对高岭土(kaolin)进行表面改性,制备了改性kaolin (M-kaolin),然后将聚丙烯(PP)接枝上顺丁烯二酸酐(MAH),制备了PP-g-MAH,将两者经过熔融共混制备了PP-g-MAH/M-kaolin复合材料,研究了M-kaolin添加量对复合材料力学性能和热稳定性的影响。结果表明,当M-kaolin粒子质量分数为1%时,PP-g-MAH/M-kaolin复合材料的拉伸强度和断裂伸长率达到最大值,与纯PP相比分别提高了10.4%和122%;当M-kaolin粒子质量分数为2%时,复合材料的缺口冲击强度达到最大值,较纯PP提高了96.5%,且热稳定性最好。这表明kaolin粒子经KH550改性且PP经MAH接枝后,PP与kaolin相容性得到优化,从而使复合材料的强度和韧性都得到了提高。%γ-aminopropyltriethoxysilane (KH550) was used to modify kaolin for preparing surface modified kaolin (M-kaolin) and polypropylene (PP) was grafted with MAH for preparing PP-g-MAH,then a series of PP-g-MAH/M-kaolin composites were prepared by melt blending method. The results show that when the mass fraction of M-Kaolin is 1%,the tensile strength and elongation at break of the composite reach the maximum and improves by 10.4%and 122%respectively comparing with PP,when the mass fraction of M-Kaolin is 2%,the composite has the highest impact strength and improves by 96.5%comparing with PP, meanwhile,it's thermal stability is best. These indicate that kaolin being modified by KH550 and PP being grafted with MAH can optimize the compatibility of kaolin and PP and improve the strength and toughness of the composite.

  4. Cartilage grafting in facial reconstruction with special consideration of irradiated grafts

    Energy Technology Data Exchange (ETDEWEB)

    Donald, P.J.

    1986-07-01

    The search for the perfect facial implant for reconstruction of the face continues. Cartilage, once thought to be an undesirable graft material because of its propensity for absorption, has regained popularity in the past decade. Various preparation techniques have been employed to ensure graft sterility and diminished absorption. An improved understanding of cartilage structure and physiology has shed considerable light on the host-graft relationship. Gamma irradiation is a time-honored method of preservation. An experiment was undertaken to investigate the physiology of irradiated cartilage grafts following prolonged implantation on the facial skeleton of sheep and dog. Merthiolate preserved grafts were used as controls. Direct observation, histochemical techniques, autoradiography, and transmission electron micrography were used to determine chondrocyte viability and matrix composition. It was surprising to note that following implantation of 16 to 72 months, complete resorption was seen in 87.7% of the irradiated grafts and in 43.8% of the Merthiolate stored controls. Many of the grafts acquired chondrocytes from the host and produced new proteoglycan matrix as well as undergoing some degree of ossification. A comparison to the clinical situation in humans is made. 98 references.

  5. Cartilage grafting in facial reconstruction with special consideration of irradiated grafts

    International Nuclear Information System (INIS)

    The search for the perfect facial implant for reconstruction of the face continues. Cartilage, once thought to be an undesirable graft material because of its propensity for absorption, has regained popularity in the past decade. Various preparation techniques have been employed to ensure graft sterility and diminished absorption. An improved understanding of cartilage structure and physiology has shed considerable light on the host-graft relationship. Gamma irradiation is a time-honored method of preservation. An experiment was undertaken to investigate the physiology of irradiated cartilage grafts following prolonged implantation on the facial skeleton of sheep and dog. Merthiolate preserved grafts were used as controls. Direct observation, histochemical techniques, autoradiography, and transmission electron micrography were used to determine chondrocyte viability and matrix composition. It was surprising to note that following implantation of 16 to 72 months, complete resorption was seen in 87.7% of the irradiated grafts and in 43.8% of the Merthiolate stored controls. Many of the grafts acquired chondrocytes from the host and produced new proteoglycan matrix as well as undergoing some degree of ossification. A comparison to the clinical situation in humans is made. 98 references

  6. Improvement of tomato local varieties by grafting in organic farming

    Science.gov (United States)

    Moreno, Marta M.; Villena, Jaime; Moreno, Carmen; García, Arántzazu M.; Mancebo, Ignacio; Meco, Ramón

    2015-04-01

    Grafting is the union of two or more pieces of living plant tissue that grow as a single plant. The early use of grafted vegetables was associated with protected cultivation which involves successive cropping (Lee et al., 2010). For this reason, in the past, grafting was used with vegetable crops to limit the effects of soil-borne diseases. However, the reasons for grafting as well as the kinds of vegetable grafted have increased considerably over the years. In tomato (Solanum lycopersicum L.), one of the most important horticultural crops in the world, the effect of grafting has also been widely studied. These effects on commercial tomato varieties can be summarized in increasing plant vigor and crop yield or inducing tolerance to abiotic stresses, although the effects on tomato fruit quality or on the sensory properties are not so patent (David et al., 2008). However, a few studies about the effect of grafting on local tomato varieties, which are especially recommended for organic production in spite of their lower yields in many cases, have been developed. In this work we evaluated the effect of grafting on tomato local varieties under organic management using vigorous commercial rootstocks, and aspects related to vigor, yield and tomato fruit composition were analyzed. In general terms, grafting increased the plant vigor, the crop yield and the fruit antioxidant content, although no modification of morphological fruit attributes was observed. Keywords: grafting, Solanum lycopersicum L., local varieties, organic farming. References: Davis A.R., Perkins-Veazie P., Hassell R., Levi A., King S.R., Zhang X. 2008. Grafting effects on vegetable quality. HortScience 43(6): 1670-1671. Lee J.M., Kubota C., Tsao S.J., Bie Z., Hoyos-Echevarría P., Morra L., Oda M. 2010. Current status of vegetable grafting: Diffusion, grafting techniques, automation. Scientia Horticulturae 127: 93-105.

  7. [Tracheal replacement grafts: current options].

    Science.gov (United States)

    Dulguerov, Pavel; Soccal, Paola M; Bouayed, Salim; Huber, Olivier; Pittet, Brigitte

    2011-10-01

    A critical review of publications on tracheal reconstruction is presented. The extent of the resection defect in terms of horizontal circumference or longitudinal extension determines the difficulty of the reconstruction. To allow a valid comparison, a classification of tracheal defects is proposed. The reconstruction materials can be subdivided into synthetic grafts, autografts, allografts, and bioengineering constructs. Reconstruction of tracheal defects greater than half of the tracheal length was not possible until recently. Numerous publications on animal experimental techniques, and rare human case reports show few successful outcomes. During the last five years, new reconstructive options have emerged: autograft of composite flaps mimicking tracheal architecture and bioengineered tracheal constructs. PMID:22046681

  8. Produtividade e composição físico-química de bagas de cultivares de uva em distintos porta-enxertos Productivity and physicochemical composition of berries of grapevine cultivars grafted onto different rootstocks

    Directory of Open Access Journals (Sweden)

    Renata Vieira da Mota

    2009-06-01

    Full Text Available O objetivo deste trabalho foi avaliar a influência de nove porta-enxertos na produção e composição química das bagas de uvas de mesa e de processamento durante o período de 2006 a 2008 em Caldas, MG. As cultivares Niágara Rosada e Folha de Figo foram enxertadas sobre 'IAC 572', 'IAC 313', 'IAC 766', '420 A', '1103 Paulsen', 'Traviú', '196-17', 'Gravesac' e 'RR 101-14' e submetidas ao delineamento em blocos ao acaso com dez tratamentos (nove porta-enxertos e o pé-franco e quatro repetições. Ambas cultivares apresentaram maior produção sobre 'IAC 572', porém com prejuízo para a qualidade das bagas que apresentaram menor relação sólidos solúveis/acidez, menor teor de antocianinas e de compostos fenólicos e maior acidez. A absorção de potássio foi mais dependente do porta-enxerto em 'Niágara Rosada'; a maior absorção foi com os porta-enxertos 'IAC 766' e 'Traviú'. Videiras enxertadas sobre '196-17' apresentaram o menor teor de potássio nas bagas. 'Niágara Rosada' apresentou produção de 9 kg por planta e elevada relação sólidos solúveis/acidez sobre 'RR 101-14', '420 A' e 'Gravesac'. Entretanto, 'Gravesac' proporcionou maior concentração de antocianinas. 'Folha de Figo' enxertada em '196-17' apresentou elevado teor de sólidos solúveis, antocianinas e fenólicos nas cascas e menor teor de acidez e fenólicos nas sementes, além de produção de 5 kg por planta, estatisticamente semelhante aos porta-enxertos mais produtivos.This work aimed at evaluating the influence of nine rootstocks on the productivity and chemical composition of table and processing grapes from 2006 to 2008 in Caldas, MG. The cultivars Niagara Rosada and Folha de Figo were grafted onto 'IAC 572', 'IAC 313', 'IAC 766', '420 A', '1103 Paulsen', 'Traviú', '196-17', 'Gravesac' and 'RR 101-14' and submitted to a randomized block design with ten treatments (nine rootstocks and ungrafted plant with four replicates. Both cultivars had higher yields

  9. Radiation-induced grafting of sweet sorghum stalk for copper(II) removal from aqueous solution

    International Nuclear Information System (INIS)

    Highlights: • Radiation-induced grafting was used to modify the stalk. • Cellulose, hemicellulose and lignin participated in grafting reaction. • Both the structure and composition of stalk had influence on grafting. • The sorption capacity of the grafted stalk increased about five times. -- Abstract: The influence of main components (cellulose, hemicellulose and lignin) of the sweet sorghum stalk on radiation-induced grafting reaction and adsorption of copper from aqueous solution was investigated. Sweet sorghum stalk was grafted with acrylic acid induced by γ-irradiation. The results showed that the grafted stalk contained 1.6 mmol/g carboxyl groups, and its maximal adsorption capacity was 13.32 mg/g. The cellulose, hemicellulose and lignin of the raw materials were confirmed to involve in grafting reaction through comparing the grafting yield and the structure of the grafted materials. Both the structure and the composition of the sweet sorghum stalk had influence on the grafting reaction and adsorption capacity. The adsorption capacity of the grafted sweet sorghum stalk increased about five times, and the adsorption isotherm of the grafted materials conformed to the Langmuir model. The main mechanism for copper adsorption involved in ion exchange

  10. Radiation-induced grafting of sweet sorghum stalk for copper(II) removal from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Jing; Hu, Jun [Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084 (China); Wang, Jianlong, E-mail: wangjl@mail.tsinghua.edu.cn [Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084 (China); Key Laboratory of Advanced Reactor Engineering and Safety, Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2013-11-15

    Highlights: • Radiation-induced grafting was used to modify the stalk. • Cellulose, hemicellulose and lignin participated in grafting reaction. • Both the structure and composition of stalk had influence on grafting. • The sorption capacity of the grafted stalk increased about five times. -- Abstract: The influence of main components (cellulose, hemicellulose and lignin) of the sweet sorghum stalk on radiation-induced grafting reaction and adsorption of copper from aqueous solution was investigated. Sweet sorghum stalk was grafted with acrylic acid induced by γ-irradiation. The results showed that the grafted stalk contained 1.6 mmol/g carboxyl groups, and its maximal adsorption capacity was 13.32 mg/g. The cellulose, hemicellulose and lignin of the raw materials were confirmed to involve in grafting reaction through comparing the grafting yield and the structure of the grafted materials. Both the structure and the composition of the sweet sorghum stalk had influence on the grafting reaction and adsorption capacity. The adsorption capacity of the grafted sweet sorghum stalk increased about five times, and the adsorption isotherm of the grafted materials conformed to the Langmuir model. The main mechanism for copper adsorption involved in ion exchange.

  11. Biofabrication and testing of a fully cellular nerve graft

    International Nuclear Information System (INIS)

    Rupture of a nerve is a debilitating injury with devastating consequences for the individual's quality of life. The gold standard of repair is the use of an autologous graft to bridge the severed nerve ends. Such repair however involves risks due to secondary surgery at the donor site and may result in morbidity and infection. Thus the clinical approach to repair often involves non-cellular solutions, grafts composed of synthetic or natural materials. Here we report on a novel approach to biofabricate fully biological grafts composed exclusively of cells and cell secreted material. To reproducibly and reliably build such grafts of composite geometry we use bioprinting. We test our grafts in a rat sciatic nerve injury model for both motor and sensory function. In particular we compare the regenerative capacity of the biofabricated grafts with that of autologous grafts and grafts made of hollow collagen tubes by measuring the compound action potential (for motor function) and the change in mean arterial blood pressure as consequence of electrically eliciting the somatic pressor reflex. Our results provide evidence that bioprinting is a promising approach to nerve graft fabrication and as a consequence to nerve regeneration. (paper)

  12. Crystallization of calcium carbonate on radiation-grafted polyethylene films

    International Nuclear Information System (INIS)

    In biomineralization processes, nucleation and growth of inorganic crystals can be regulated by organic template molecules. This has inspired great interest in studying mimic biomineralization. In our study, growing CaCO3 crystals on PE films functionalized through radiation-induced grafting was attempted. PE films grafted with different functional groups of different distributions and densities were used as substrates for CaCO3 nucleation and crystal growth from Ca(HCO3)2 supersaturated solution under different environmental conditions (e.g. additives and temperature) to study the effects and mechanisms. The grafted PE films were analyzed by ATR-FTIR and AFM, and the evolution of CaCO3 crystal formation on the grafted PE film was characterized by SEM, FTIR, and XRD. The results indicated that heterogeneous nucleation of CaCO3 crystals was significantly facilitated by the functional groups grafted on the surface of PE films, that the morphology of CaCO3 crystals could be controlled by distribution and density of the grafted functional groups, and that polymorphism of CaCO3 crystal could be regulated by selection of grafting functional groups. We believe that studying the effects of chemical structures on inorganic crystallization is of great importance since radiation-induced grafting is an effective method to graft desirable functional groups onto different polymers by selected monomers, in the endeavor of developing advanced organic/inorganic composites with high performance, with a wide availability of polymers, monomers and inorganic solutions. (authors)

  13. Graft copolymers of polypropylene films. 1. radiation induced grafting of mixed monomers. Vol. 3

    International Nuclear Information System (INIS)

    Radiation graft copolymerization of co monomer mixtures of acrylic acid (AAC), and styrene (S) onto polypropylene (PP) film by mutual method has been investigated. The effects of different factors that may affect the grafting yield such as inhibitor concentration (Mohr's salt), solvent composition (MeOH and H2 O), radiation dose and dose rate were considered. It was found that the role of Mohr's salt is very effective when the ratio of AAC in the co monomer mixtures was at lower values. However, the addition of 1.25 Wt% of Mohr's salt reduced the homo polymer formation and enhances the grafting process. Graft copolymerization in presence of solvent mixture composed of methanol and water was found to afford higher grafting than in pure methanol regardless of the composition of the co monomer mixture used. However, the highest degree of grafting was obtained at a solvent composition of 20% H2 O:80%MeOH and a co monomer mixture of 20%AAC:80%sty. An attempt was made to determine each PAAC and PS fractions in the total graft yield obtained. Two methods of analysis based on using the reactivity ratios reported in literature, elemental analysis and IR spectroscopy. The determination of poly (acrylic acid) and polystyrene fractions by elemental analysis is believed more accurate than these by reactivity ratio. The precise results obtained by elemental analysis with respect to the chemical structure of known polymer prepared under identical conditions. The results obtained by IR measurements go well with that obtained with the reactivity ratio methods. 5 figs., 3 tabs

  14. 微波接枝CPVC改性秸秆纤维/HDPE复合材料的界面性能%The Interfacial Properties of Straw/HDPE Composite Grafted CPVC by Microwave

    Institute of Scientific and Technical Information of China (English)

    李淳; 曾秋苑; 孙蓉; 邓华; 敖宁建

    2011-01-01

    利用微波接枝CPVC复配偶联剂处理秸秆纤维表面,采用光学法液滴形态分析系统测定处理前后秸秆微粉的动态接触角及表面能变化,并制备相应的复合材料进行力学性能测试.研究结果表明:微波接枝CPVC复配偶联剂界面改性方法对秸秆纤维有较好的改性效果,改性后秸秆纤维的平衡接触角θe由74.65.上升至98.96.,从明显的亲水性转变为疏水性;而表面能则有不同程度减小,改性后秸秆纤维表面能(23.68 mJ/m2)低于HDPE基体(28.61 mJ/m2);经微波接枝CPVC改性后秸秆纤维复合材料保持了良好的力学性能.较透彻地了解秸秆纤维复合材料的复合界面特性及其复合机理,设计和制造不同性能、满足不同应用领域要求的纤维复合材料产品,是秸秆纤维复合材料研究工作者至今仍在继续探索的重要研究领域.%CPVC double-component blending coupling agents were used to treat the surface of straw fibers by microwavegrafting. The change of dynamic contact angle and surface energy of untreated and treated straw micro powder were measured by optical method, and relative composite were prepared to carry mechanics properties tests. The experimental results showed that the surface modification using microwave-grafted CPVC double-component blending coupling agents had relative effect on straw fiber. The balance contact angle (θe) of treated straw increased from 74.65° to 98.96°, and the straw was converted from obvious hydrophilic to hydrophobic. The surface energy had some degree of decrease after modification, from 28.61 mJ/m2 to 23.68 mJ/m2. The straw composite maintained well mechanics properties after modified by microwave-grafted CPVC. The composite interface characteristics and mechanism of straw composite were studied. In order to meet demands of different application fields, designing and producing fiber composites with different functions were necessary, and it was an important research field

  15. Studies on surface modification of UHMWPE fibers via UV initiated grafting

    International Nuclear Information System (INIS)

    In this research, the surface of ultra high molecular weight polyethylene (UHMWPE) fiber was modified by high energy ultraviolet (UV) initiated grafting reactions and acrylamide groups were grafted onto UHMWPE chains. The initiating and grafting mechanism of the reactions was studied. Some important factors influencing the grafting effect, e.g. crystallinity of UHMWPE fiber, concentration of the initiating reagent, grafting time and the concentration of grafting monomer (acrylamide) were discussed. Fourier transform infrared (FTIR) was used to manifest the mechanism of the grafting reaction. Scanning electron microscopy (SEM) was used to show the morphology changing of the fiber surface. Single fiber pull-out strength and ILSS tests of the composite showed that acrylamide grafted onto the surface of the fiber could improve the interfacial adhesion between treated fibers and matrices

  16. Graft Copolymers of Maleic Anhydride and Its Isostructural Analogues: High Performance Engineering Materials

    CERN Document Server

    Rzayev, Zakir M O

    2011-01-01

    This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional and non-conventional synthetic and natural polymers, including biodegradable polymers, mechanism of grafting and graft copolymerization, in situ grafting reactions in melt by reactive extrusion systems, in solutions and solid state (photo- and plasma-induced graftings), and H-bonding effect in the reactive blend processing. The structural phenomena, unique properties and application areas of these copolymers and their various modifications and composites as high performance engineering materials have been also described.

  17. Radiation-initiated graft polymerization of methyl acrylate onto chrome-tanned sheepskin

    International Nuclear Information System (INIS)

    Radiation grafting method was applied to obtain leather-polymer composite. Grafting of methyl acrylate onto chrome-tanned, bluestock sheepskin was investigated under the initiatory effect of 60Co radiation of 0.20 11.50 Mrad. The percent of grafting was determined and water adsorption and shrinkage temperature measurements were carried out. It was shown that 2-4 Mrad is convenient to produce leather-polymer composite. (author)

  18. Bone Graft Alternatives

    Science.gov (United States)

    ... cadavers. The types of allograft bone used for spine surgery include fresh frozen and lyophilized (freeze dried). The ... the most common uses of bone grafts in spine surgery is during spinal fusion. The use of autogenous ...

  19. Proximal Tibial Bone Graft

    Science.gov (United States)

    ... Complications Potential problems after a PTBG include infection, fracture of the proximal tibia and pain related to the procedure. Frequently Asked Questions If proximal tibial bone graft is taken from my knee, will this prevent me from being able to ...

  20. Epidermal skin grafting.

    Science.gov (United States)

    Herskovitz, Ingrid; Hughes, Olivia B; Macquhae, Flor; Rakosi, Adele; Kirsner, Robert

    2016-09-01

    Autologous skin grafts, such as full- and split-thickness, have long been part of the reconstructive ladder as an option to close skin defects. Although they are effective in providing coverage, they require the need for a trained surgeon, use of anaesthesia and operating room and creation of a wound at the donor site. These drawbacks can be overcome with the use of epidermal skin grafts (ESGs), which can be harvested without the use of anaesthesia in an office setting and with minimal to no scarring at the donor site. ESGs consist only of the epidermal layer and have emerged as an appealing alternative to other autologous grafts for the treatment of acute and chronic wounds. In this article, we provide an overview of epidermal grafting and its role in wound management. PMID:27547964

  1. [Zaidemberg's vascularized radial graft].

    Science.gov (United States)

    Saint-Cast, Y

    2010-12-01

    In 1991, Carlos Zaidemberg described a new technique to repair scaphoid non-unions with a vascularized bone graft harvested from the radial styloid process. An anatomic study based on 30 dissections after colorized latex injection established the constancy of the radial styloid process's artery, while showing that its origin, course and length were subject to variations. In a retrospective series of 38 cases over a period of 10 years, the vascularized bone graft was indicated for: (1) scaphoid non-union with the presence of avascular changes of the proximal fragment (23 cases); (2) failed prior reconstruction with bone graft and internal fixation (nine cases); (3) degenerative styloid-scaphoid arthritis (three cases); (4) fracture on Preiser dystrophy (three cases). The five steps of the simplified operative technique without dissection of the vascular pedicle include: (1) longitudinal dorso-radial approach, identification of the periosteal portion of the radial styloid process artery; (2) incision of the first and second compartments, longitudinal arthrotomy under the second compartment; (3) styloidectomy and transversal resection of the scaphoid non-union and sclerotic bone; (4) elevation of the vascularized bone graft; (5) transversal and radial insertion of the vascularized bone graft, osteosynthesis by two or three K-wire touching the scaphoid's radial edge. Scaphoid union was obtained in 33 cases out of 38. The only postoperative complications were two transient radial paresthesia. The standardized surgical procedure using vascularized bone graft harvested from the radial styloid process provides an efficient scaphoid reconstruction. PMID:21087882

  2. Cellulose functionalization via high-energy irradiation-initiated grafting of glycidyl methacrylate and cyclodextrin immobilization

    International Nuclear Information System (INIS)

    Cotton-cellulose was functionalized using gamma-irradiation-induced grafting of glycidyl methacrylate (GMA) to obtain a hydrophobic cellulose derivative with epoxy groups suitable for further chemical modification. Two grafting techniques were applied. In pre-irradiation grafting (PIG) cellulose was irradiated in air and then immersed in a GMA monomer solution, whereas in simultaneous grafting (SG) cellulose was irradiated in an inert atmosphere in the presence of the monomer. PIG led to a more homogeneous fiber surface, while SG resulted in higher grafting yield but showed clear indications of some GMA-homopolymerization. Effects of the reaction parameters (grafting method, absorbed dose, monomer concentration, solvent composition) were evaluated by SEM, gravimetry (grafting yield) and FTIR spectroscopy. Water uptake of the cellulose decreased while adsorption of a pesticide molecule increased upon grafting. The adsorption was further enhanced by β-cyclodextrin immobilization during SG. This method can be applied to produce adsorbents from cellulose based agricultural wastes. - Highlights: → Fundamentals of two grafting methods for biomass utilization as adsorbents. → Simultaneous grafting is more efficient and useful than the pre-irradiation one. → Methanol/water/surfactant combined solvent gives the best grafting yield. → Grafted cellulose increased hydrophobicity and adsorption of phenolic compounds. → Improved adsorption by bonding β-cyclodextrin during simultaneous grafting.

  3. The study on grafting comonomer of n-butyl acrylate and styrene onto poly(ethylene terephthalate) film by gamma-ray induced graft copolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Ping Xiang; Wang Mozhen [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Ge Xuewu, E-mail: xwge@ustc.edu.c [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2010-09-15

    Poly(ethylene terephthalate) (PET) film was successfully grafted with n-butyl acrylate and styrene comonomer through gamma-ray induced graft copolymerization. The degree of grafting (DG) and the composition of grafted side chain were characterized by {sup 1}H NMR. It was found that St can inhibit the homopolymerization of BA effectively and increase the DG when the concentration of comonomer mixture is kept constant. The proportion of St to BA in grafted side chain has a positive dependence on the feed ratio of St, which ultimately approaches the feed ratio. The thermal properties of poly(ethylene terephthalate)-graft-poly(n-butyl acrylate-co-styrene) (PET-g-P(BA-co-St)) films were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The T{sub g} of PET decreases with the DG, indicating that the grafted P(BA-co-St) copolymer has good compatibility with PET backbone.

  4. Epoxy and Silicone Optical Nanocomposites Filled with Grafted Nanoparticles

    Science.gov (United States)

    Tao, Peng

    Polymer nanocomposites, as a technologically important class of materials, exhibit diverse functional properties, and are used for applications ranging from structural and biomedical to electronic and optical. The properties of polymer nanocomposites are determined, in part, by the chemical composition of the polymer matrix and the nanofillers. Their properties are also sensitive to the geometry and size of the nanofillers, and to spatial distribution of the fillers. Control of the nanoparticle size and dispersion within a given polymer provides opportunities to tailor and optimize the properties of nanocomposites for specific application. For optical applications such as encapsulation of light emitting diodes (LEDs), polymer nanocomposites filled with homogeneously dispersed nanoparticles would endow the polymer encapsulant with new functionality without sacrificing optical transparency. To this end, this thesis focuses on developing a simple and versatile approach towards the fabrication of epoxy and silicone transparent nanocomposites using matrix compatible chain-grafted nanoparticles as fillers, and studying the optical properties of the nanocomposites. The surface chemistry and grafted polymer chain design have been shown to play an important role in determining the dispersion state of the grafted nanoparticles and hence the final optical properties of the nanocomposites. To prepare transparent epoxy nanocomposites, poly (glycidyl methacrylate) (PGMA) chains were grafted onto the optical nanoparticle surfaces via a combined phosphate ligand exchange process and azide-alkyne "click" chemistry. The dispersion behavior of PGMA-grafted nanoparticles within the epoxy matrix was investigated by systematically varying the grafting density and grafted chain length. It was found that within the small molecular weight epoxy resins, the dispersion states are more sensitive to the grafting density than the molecular weight of grafted chains. With high grafting densities

  5. Axillobifemoral bypass grafting

    Directory of Open Access Journals (Sweden)

    Davidović Lazar B.

    2004-01-01

    Full Text Available INTRODUCTION Axillo-femoral bypass (AxF means connecting the axillar and femoral artery with the graft that is placed subcutaneously [1]. Usually, this graft is connected with contralateral femoral artery via one accessory subcutaneous graft, and this connection is known as axillobifemoral bypass (AxFF. This extra-anatomic procedure is an alternative method to the standard reconstruction of aortoiliac region when there are contraindications for general or local reasons. OBJECTIVE The objective of this paper is to show early and late results of AxFF bypass grafting as well as to show the indications for AxFF bypass. METHODS The sample consisted of 37 patients. The procedure was performed in 28 patients who suffered from aortoiliac occlusive disease and who were at high risk due to the comorbidity- in one patient with the rupture of juxtarenal aneurysm of abdominal aorta; in five patients with aortoenteric fistula, in two patients with iatrogenic lesion of abdominal aorta and in one female patient with anus preternaturalis definitivus who was treated for rectovaginal fistula. Donor's right axillary artery was used in 26 cases (70.3%, and donor's left axillary artery was used in 9 cases (29.7%. Dacron graft was used in 34 patients and Polytetrafluo-roethlylene graft was used in three patients. Simultaneously, profundo-plastic was done in four patients and femoro-popliteal bypass was performed in three patients. In five patients who suffered from aortoenteric fistula, simultaneous intervention of gastrointerstinal system has been done, x2 test was used for statistical evaluation and life table method was used for verification of late graft patency. RESULTS The rate of early postoperative mortality was 13.5%. The causes of death were: sepsis -1, MOFS - 3, and infarct myocardium -1. The mean follow up period was 40.1 months, ranging from six months to 17 years. During the follow up period, an early graft thrombosis was identified in two and late graft

  6. THRUST FORCE AND TORQUE IN DRILLING THE NATURAL FIBER REINFORCED POLYMER COMPOSITE MATERIALS AND EVALUATION OF DELAMINATION FACTOR FOR BONE GRAFT SUBSTITUTES -A WORK OF FICTION APPROACH

    Directory of Open Access Journals (Sweden)

    D. CHANDRAMOHAN

    2010-11-01

    Full Text Available This paper discusses about the Natural Fiber Reinforced Composite Materials contribution as bone implants. Biomaterial science is an interdisciplinary field that represents one of the most sophisticated trends in worldwide medical practice. In the last decades, researchers have developed new materials to improve the quality of human life. Owing to the frequent occurrence of bone fractures, it is important to develop a plate material for fixation on the fractured bone. These plate materials have to be lightweight, allow stiffness, and be biocompatible with humans. Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials, owing to the need for joining fractured bone by means of plate material in the field of orthopedics. An effort to utilize theadvantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers has been made through fabrication of Natural fiber powdered material (Sisal (Agave sisalana, Banana (Musa sepientum, and Roselle (Hibiscus sabdariffa reinforced polymer composite plate material by using bio epoxy resin Grade 3554A and Hardner 3554B. Instead of orthopedics alloys such as Titanium, Cobalt chrome, Stainless steel, and Zirconium, this plate material can be used for internal fixationand aso external fixation on human body for fractured bone. The present work focuses on the prediction of thrust force and torque of the natural fiber reinforced polymer composite materials, and the values, compared with the Regression model and the Scheme of Delamination factor / zone using machine vision system, also discussed with the help of Scanning Electron Microscope [SEM].

  7. Preparation and Properties of Boron Nitride/Epoxy Composite Grafted with Hyperbranched Aromatic Polyamide%超支化聚芳酰胺接枝氮化硼/环氧复合材料的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    彭鹏; 虞锦洪; 江平开

    2012-01-01

    采用两步法将超支化聚芳酰胺接枝到氮化硼粒子表面,并将其掺入到环氧树脂中,制备了一系列复合材料,并对复合材料的微观形貌、玻璃化转变温度、导热性能及电气强度进行了测试研究.结果表明:超支化聚芳酰胺接枝氮化硼粒子在环氧树脂中有较好的分散性,复合材料的电气强度、玻璃化转变温度和导热系数均得到了提高.%The boron nitride(BN) particles were grafted with hyperbranched aromatic polyamide by two-step method, and then an epoxy composite was prepared by adding the grafted boron nitride particles. The morphology, glass transition temperature, thermal conductivity and electric strength of the composite were studied. The results show that the BN particles grafted with hyperbranched aromatic polyamide can well dispense in the epoxy resin; and the glass transition temperature, thermal conductivity and electric strength of the composite can be improved.

  8. Thermosensitive membranes by radiation-induced graft polymerization of N-isopropyl acrylamide/acrylic acid on polypropylene nonwoven fabric

    International Nuclear Information System (INIS)

    Radiation-induced graft copolymerization of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) mixture was investigated on polypropylene nonwoven fabric to develop a thermosensitive material. The grafting was carried out using methanol, acetone and butanone as homopolymerization inhibitor in the reaction medium. Butanone was observed to give the maximum grafting. It was observed that the grafting is significantly influenced by the reaction conditions, such as radiation dose, monomer concentration, monomer ratio, solvent composition and reaction temperature. The degree of grafting increased as the AA and NIPAAm concentration in the reaction medium increased. The degree of grafting increased as the AA fraction in the NIPAAm/AA mixture increased. The temperature dependence of the grafting process is very much governed by the thermosensitive nature of the grafted chains right from the stage when initial grafting has taken place.

  9. Preparation and Thermal Property of Liquid Crystal Epoxy Grafted Alumina/Epoxy Resin Composite%环氧液晶接枝氧化铝/环氧树脂复合材料的制备与热性能

    Institute of Scientific and Technical Information of China (English)

    何子海; 虞锦洪

    2015-01-01

    将支化环氧液晶接枝到氧化铝纳米颗粒表面,再将其加入到环氧树脂中制备成复合材料,并对环氧液晶接枝氧化铝/环氧树脂复合材料的热性能进行研究。结果表明:加入环氧液晶接枝氧化铝纳米颗粒后,环氧树脂复合材料的导热系数从纯环氧树脂的0.16 W/(m·K)提高到BLCE-g-Al2O3含量为30%时的0.238 W/(m·K),增加了48.75%;复合材料的初始储能模量比纯环氧树脂的初始储能模量提高了181 MPa,玻璃化转变温度提高了24℃。随着Al2O3填充量的增加,复合材料的热膨胀系数逐渐减小。%Alumina nanoparticles were grafted by branched liquid crystal epoxy (BLCE-g-Al2O3), and BLCE-g-Al2O3/EP composites were prepared through adding the BLCE-g-Al2O3 into epoxy matrix, and then their thermal properties were investigated. The results show that the thermal conductivity of the com-posites increases from 0.16 W/(m·K) of pure epoxy resin to 0.238 W/(m·K) with 30% of BLCE-g-Al2O3 content, and the thermal conductivity increases by 48.75%. The storage modulus and glass transition temperature of the epoxy composites increase by 181 MPa and 24℃, respectively. With the increase of BLCE-g-Al2O3 content, the thermal expansion coefficient of the epoxy composites decreases.

  10. 磷酸钙骨水泥/骨形态发生蛋白复合人工骨的生物相容性%Biocompatibility of calcium phosphate cement/BMP composite as bone graft material

    Institute of Scientific and Technical Information of China (English)

    孙明林; 胡蕴玉; 贾新斌; 李丹; 刘忠湘; 朱德生

    2001-01-01

    AIM To construct CPC/BMP composite by combining CPC with BMP, and to detect their biocompatibity. METHODS The toxicity, pyrogen, hemolytic activities and immunogen were detected by means of animal test, cell culture, hemolysis test and histochemical technique. RESULTS The composites were found no toxicity and no pyrogen by animal test, no hemolytic activities and couldn't influence the coagulate of blood in vitro. When the materials were grafted into the muscle pounches in the thigh of mice or rabbits, no obvious specific antibodies produced were detected in serum by ELISA, nor were significant immune reaction of foreign body observed by histochemistry technique. The composites were also testified no cytotoxicity in vitor for the proliferation of cultured cells couldn' be inhibited. CONCLUSION The CPC/BMP composite might have good biocompatibility and be safe for clinical use.%目的将自行合成的磷酸钙骨水泥(CPC)作为载体与BMP复合成人工骨,检测其生物相容性. 方法制备CPC/BMP及CPC骨块,通过体外实验、细胞培养、动物实验等方法观察其毒性、免疫原性、对血液系统的影响等生物相容性指标. 结果动物实验表明材料属无毒级,不含致热原,体外试验不引起溶血反应,对凝血功能无明显影响. 植入兔或小鼠肌袋内未检测出特异性抗体. 组织学检查未见免疫排斥反应,对肌肉无刺激作用.对体外培养的细胞增殖没有明显抑制作用.结论材料有较好的生物相容性,临床使用安全.

  11. Arteriovenous shunt graft ulceration with sinus and graft epithelialization

    Directory of Open Access Journals (Sweden)

    Pooja Singhal

    2015-03-01

    Full Text Available Arteriovenous fistula and grafts are used as access sites for patients with chronic kidney disease and are prone for complications. Stent grafts are used to treat access site complications. We report a rare and unusual finding of epithelialization of the sinus tract and the lumen of a polytetrafluoroethylene graft, following ulceration of the overlying skin.

  12. Composites

    OpenAIRE

    Zhao, Hanqing; Guo, Yuanzheng

    2014-01-01

    This thesis was a literature study concerning composites. With composites becoming increasingly popular in various areas such as aerospace industry and construction, the research about composites has a significant meaning accordingly. This thesis was aim at introducing some basic information of polymer matrix composites including raw mate-rial, processing, testing, applications and recycling to make a rough understanding of this kind of material for readers. Polymeric matrices, fillers,...

  13. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  14. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2010-01-01

    New Year is an open composition to be realised by improvising musicians. It is included in "From the Danish Seasons" (see under this title). See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You...

  15. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  16. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all...

  17. Slicing, skinning, and grafting

    OpenAIRE

    Dumas, David; Kent IV, Richard P.

    2007-01-01

    We prove that a Bers slice is never algebraic, meaning that its Zariski closure in the character variety has strictly larger dimension. A corollary is that skinning maps are never constant. The proof uses grafting and the theory of complex projective structures.

  18. Acrylonitrile grafted to PVDF

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jin; Eitouni, Hany Basam

    2015-03-31

    PVDF-g-PAN has been synthesized by grafting polyacrylonitrile onto polyvinylidene fluoride using an ATRP/AGET method. The novel polymer is ionically conducive and has much more flexibility than PVDF alone, making it especially useful either as a binder in battery cell electrodes or as a polymer electrolyte in a battery cell.

  19. Synergistic photocatalytic inactivation mechanisms of bacteria by graphene sheets grafted plasmonic AgAgX (X = Cl, Br, I) composite photocatalyst under visible light irradiation.

    Science.gov (United States)

    Xia, Dehua; An, Taicheng; Li, Guiying; Wang, Wanjun; Zhao, Huijun; Wong, Po Keung

    2016-08-01

    By coupling graphene sheet and plasmonic photocatalysis technologies, a series of AgAgX/RGOs (X = Cl, Br, I; RGO = reduced graphene oxide) composites were prepared and found to be efficient antimicrobial agents for water disinfection upon visible light. Attributed to the efficient charge transfer by RGO sheets, the optimum AgAgBr/0.5% RGO could completely inactivate 2 × 10(7) cfu mL(-1) of Escherichia coli within 8 min, much faster than bare AgAgBr within 35 min. The synergistic antimicrobial mechanism of AgAgBr/0.5% RGO was studied by Ag(+) ions release evaluation, radical scavengers study, and radical determination. The enhanced photocatalytic activity of irradiated AgAgBr/0.5% RGO originated from the synergistic activities of its three components including Ag, AgBr and RGO, and the proposed mechanisms contained enhanced attraction by RGO followed by two pathways: primary oxidative stress caused by plasma induced reactive species like H2O2 and bactericidal effect of released Ag(+) ions. Furthermore, characterization of E. coli cells using SEM, fluorescent microscopy, and cytoplasmic substance leakage illustrated that VL irradiated AgAgBr/0.5% RGO could not only cause metabolic dysfunction but also destroy the cell envelope and biomolecular, while irradiated Ag(+) ions play a differential bactericidal action with a limited metabolic injury and no cell-membrane damage. The present work provides an efficient water disinfection technology and also opens a new idea in studying the antimicrobial mechanism of plasmonic photocatalyst. PMID:27155987

  20. Synthesis and characterization of composite polymer, polyethylene glycol grafted flower-like cupric nano oxide for solid phase microextraction of ultra-trace levels of benzene, toluene, ethyl benzene and o-xylene in human hair and water samples.

    Science.gov (United States)

    Sarafraz-Yazdi, Ali; Zendegi-Shiraz, Amene; Es'haghi, Zarrin; Hassanzadeh-Khayyat, Mohammad

    2015-10-30

    In this research, poly (ethylene glycol)-poly (ethylene glycol) grafted flower-like cupric oxidenano particles (PEG-PEG-g-CuO NPs) as a novel fiber coating of solid-phase microextraction (SPME) were synthesized by using sol-gel technology. This fiber was successfully applied to extract and determine the ultra-trace levels of benzene, toluene, ethyl benzene and o-xylene in human hair using head space-solid-phase microextraction (HS-SPME) coupled to gas chromatography-flame ionization detector. Characterization and chemical composition of the nano particle was performed by Fourier transform infrared spectroscopy (FT-IR), energy dispersion spectroscopy (EDS) and back scatter analysis (BSA). These methods confirmed the successful fabrication of PEG-g-CuO NPs. The surface morphology of the fibers were inspected by scanning electron microscopy. The scanning electron microscopy (SEM) revealed many "crack-like" features and highly porous structure on the surface of fiber. The synthesized nanocomposites were used for preconcentration and extraction of benzene, toluene, ethyl benzene and o-xylene (BTEX). The effects of operating parameters such as: desorption temperature and time, extraction temperature, extraction time, stirring speed and salt effect were investigated and optimized. Under the optimal conditions, the method detection limits and the limits of quantification were between 0.00025-50.00000pgmL(-1) and 0.00200-200.00000pgmL(-1), respectively. Linearity was observed over a range 0.00200-200000.00000pgmL(-1). The relative standard deviations for one fiber (repeatability; n=5) were obtained from 3.30 up to 5.01% and between fibers or batch to batch (n=3; reproducibility) in the range of 3.63-6.21%. The developed method was successfully applied to simultaneous determination of BTEX in human hairs, tap water and distillate water. PMID:26411479

  1. Synthesis of polycaprolactone-grafted microfibrillated cellulose for use in novel bionanocomposites--influence of the graft length on the mechanical properties.

    Science.gov (United States)

    Lönnberg, Hanna; Larsson, Karolina; Lindström, Tom; Hult, Anders; Malmström, Eva

    2011-05-01

    In the present work, microfibrillated cellulose (MFC) made from bleached sulfite softwood dissolving pulp was utilized to reinforce a poly(ε-caprolactone) (PCL) biopolymer matrix. To improve the dispersibility of the hydrophilic MFC in the nonpolar matrix and the interfacial adhesion in the composite material, we covalently grafted the MFC with PCL via ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). To be able to investigate the effect of the PCL graft length on the mechanical properties of the composite material, we performed ROP to different molecular weights of the grafts. Bionanocomposites containing 0, 3, and 10 wt % MFC were prepared via hot pressing using both unmodified and PCL grafted MFC (MFC-g-PCL) as reinforcement. PCL grafting resulted in improved dispersion of the MFC in a nonpolar solvent and in the PCL matrix. The mechanical testing of the biocomposites showed an improvement in the mechanical properties for the PCL grafted MFC in comparison to ungrafted MFC. It was also shown that there was an impact on the mechanical properties with respect to the PCL graft lengths, and the strongest biocomposites were obtained after reinforcement with MFC grafted with the longest PCL graft length. PMID:21473594

  2. Graft Copolymerization of Methyl Methacrylate Monomer onto Starch and Natural Rubber Latex Initiated by Gamma Irradiation

    Directory of Open Access Journals (Sweden)

    S. Iskandar

    2011-04-01

    Full Text Available To obtain the degradable plastic, the graft copolymerization of methyl methacrylate onto starch and natural rubber latex was conducted by a simultaneous irradiation technique. Gamma-ray from cobalt-60 source was used as the initiator. The grafted copolymer of starch-polymethyl methacrylate and the grafted copolymer of natural rubber-polymethyl methacrylate were mixed in the blender, and dried it in the oven. The dried grafted copolymer mixture was then molded using hydraulic press machine. The effect of irradiation dose, composition of the grafted copolymer mixture, film forming condition and recycle effect was evaluated. The parameters observed were tensile strength, gel fraction and soil burial degradability of grafted copolymer mixture. It was found that the tensile strength of grafted copolymer mixture increased by -ray irradiation. Increasing of the grafted copolymer of natural rubber-polymethyl methacrylate content, the gel fraction and tensile strength of the grafted copolymer mixture increased. The tensile strength of the grafted copolymer mixture was increased from 18 MPa to 23 MPa after recycled (film forming reprocessed 3 times. The grafted copolymer mixture was degraded completely after soil buried for 6 months

  3. Surface analysis of plasma grafted carbon fiber

    International Nuclear Information System (INIS)

    The surface characteristics of carbon fibers were studied by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and wetting measurements. The surface of carbon fiber was modified by means of plasma graft silsesquioxane. The oxygen/carbon and silicon/carbon ratio increased rapidly after treatments. Fitting the C 1s, O 1s, and Si 2p spectra demonstrated that new photopeaks were emerged, which were indicated C-Si, Si-O groups, respectively. The degree of surface roughness and the wettability of carbon fiber surface were both increased by plasma graft silsesquioxane. The results may shed some light on the design of the appropriate surface structure, which could react with resin, and the manufacture of the carbon fiber reinforced composites

  4. Development of electron beam grafted co-polymer membranes for recovery of uranium from seawater: process parameter standardization

    International Nuclear Information System (INIS)

    Polymer matrices have been suggested for effective trapping of uranium from seawater as the trapped uranium can be easily eluted and the polymer matrix can be reused for further trapping of uranium for several cycles. Such polymer matrices have been synthesized by incorporating specific groups into some polymer backbones, which brings about changes in the physicochemical properties of parent polymer backbone and makes it suitable for uptake of uranium. Graft co-polymerization is a suitable means of incorporating desirable groups into parent polymer matrix without drastically affecting the basic properties of the substrate. Radiation grafting has proven to be an easy, reproducible and versatile technique for grafting in comparison to chemical grafting. Development of radiation-grafted copolymers for the purpose of uranium recovery from seawater has been in progress at BARC during last few years. This report describes the work carried out on radiation grafting of acrylonitrile onto thermally bonded non-woven porous polypropylene fiber sheets using electron beam irradiation by post-irradiation grafting technique. The effect of various experimental variables viz. substrate material, form of substrate material, radiation source, grafting technique, grafting dose, dose rate, temperature, grafting solution composition etc. on grafting have been reported. Grafting extent of ∼125% using technical grade chemical were achieved. The grafted nitrile groups were subsequently converted to amidoxime group by chemical treatment. (author)

  5. GRAFTING OF POLYSTYRENE ONTO A NANOMETER SILICA SURFACE BY MICROEMULSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Jian Yu; Jie Yu; Yan-fang Gao; Zhao-xia Guo

    2002-01-01

    The grafting of polystyrene onto a nanometer silica surface by microemulsion polymerization is described. Silica was functionalized with 3-methacryloxypropyltrimethoxysilane coupling agent before polymerization. A mixture of ionic and non-ionic surfactants as well as water-soluble and oil-soluble initiators were used. The effect of the amount of silica and ionic surfactant on the graft polymerization was studied. The graft polymerization procedure for styrene was also applied to methyl methacrylate. Composite particles with a core-shell structure were obtained and the yield and grafting efficiency of monomer were high.

  6. Vascular graft infections with Mycoplasma

    DEFF Research Database (Denmark)

    Levi-Mazloum, Niels Donald; Skov Jensen, J; Prag, J;

    1995-01-01

    laboratory techniques, the percentage of culture-negative yet grossly infected vascular grafts seems to be increasing and is not adequately explained by the prior use of antibiotics. We have recently reported the first case of aortic graft infection with Mycoplasma. We therefore suggest the hypothesis that...... the large number of culture-negative yet grossly infected vascular grafts may be due to Mycoplasma infection not detected with conventional laboratory technique....

  7. Environmental application of radiation grafting

    International Nuclear Information System (INIS)

    Adsorbent having high selectivity against a certain metal ion was synthesized by means of radiation-induced graft polymerization for the purpose of environmental application. The resulting adsorbents were utilized for the removal of toxic metal from scallop waste and the collection of uranium from seawater. As a novel application of grafting, the biodegradability of poly-hydroxybutylate was controlled by grafting. The biodegradability could be depressed by the graft chain and then recovered by external stimuli such as thermal and chemical treatments. (author)

  8. Axonal regeneration through arterial grafts.

    OpenAIRE

    Anderson, P. N.; Turmaine, M.

    1986-01-01

    The left common peroneal nerves of adult inbred mice were severed and allowed to regenerate through the lumina of Y-shaped tubes comprising grafts of abdominal aorta and its bifurcation. Very little regeneration took place within the grafts unless the distal nerve stump was inserted into one limb of the Y-tube. Using syngeneic grafts virtually all the axons regenerating through the lumen grew down the limb of the Y-tube containing the distal nerve. Using non-syngeneic grafts, however, a subst...

  9. Polyaniline-grafted reduced graphene oxide for efficient electrochemical supercapacitors.

    Science.gov (United States)

    Kumar, Nanjundan Ashok; Choi, Hyun-Jung; Shin, Yeon Ran; Chang, Dong Wook; Dai, Liming; Baek, Jong-Beom

    2012-02-28

    An alternative and effective route to prepare conducting polyaniline-grafted reduced graphene oxide (PANi-g-rGO) composite with highly enhanced properties is reported. In order to prepare PANi-g-rGO, amine-protected 4-aminophenol was initially grafted to graphite oxide (GO) via acyl chemistry where a concomitant partial reduction of GO occurred due to the refluxing and exposure of GO to thionyl chloride vapors and heating. Following the deprotection of amine groups, an in situ chemical oxidative grafting of aniline in the presence of an oxidizing agent was carried out to yield highly conducting PANi-g-rGO. Electron microscopic studies demonstrated that the resultant composite has fibrillar morphology with a room-temperature electrical conductivity as high as 8.66 S/cm and capacitance of 250 F/g with good cycling stability. PMID:22276770

  10. Synthesis, structure and phase transition property of acrylic acid grafted paraffin

    Science.gov (United States)

    Zhao, Xiaowen; Liu, Pengfei; Ye, Lin

    2014-05-01

    Polar monomer acrylic acid (AA) was used to modify paraffin in order to improve the latent heat of paraffin as phase change materials. The composition and sequence structure of the grafted products were characterized by FTIR, 13C NMR, 1H NMR and GPC analysis, and the thermal properties of paraffin-g-AA were investigated. It was found that AA was confirmed to be grafted onto the molecular chain of paraffin successfully. The mechanism of free radical grafting of AA may be only monomeric grafts. At low grafting ratio, the structure B can be mainly formed as a result of the radical coupling termination; while at the high grafting ratio, structure A was the primary structure as a result of the radical chain growth process. The number-average molecular weight of the grafted samples increased at first but leveled off with increasing grafting ratio, while the weight-average molecular weight increased gradually. The latent heat capacity of the grafted paraffin can be improved obviously at low grafting ratio due to the formation of structure B.

  11. Suction blister grafting - Modifications for easy harvesting and grafting

    Directory of Open Access Journals (Sweden)

    2012-01-01

    Full Text Available Suction blister grafting is a simple modality of treatment of patients with resistant and stable vitiligo. But raising the blisters may be time consuming and transferring to the recipient site may be difficult as the graft is ultrathin. By doing some modifications we can make the technique simpler and easier. We can decrease the blister induction time by intradermal injection of saline, exposure to Wood′s lamp, intrablister injection of saline. By these methods we can decrease the blister induction time from 2-3 hrs to 45-90 minutes. After harvesting the graft, it can be transferred to the recipient area by taking the graft on a sterile glass slide, on the gloved finger, rolling the graft over a sterile syringe and then spreading on the recipient area, or taking on the sterile wrapper of paraffin dressing and then placing over the recipient area.

  12. Design of a Sapling Branch Grafting Robot

    OpenAIRE

    Qun Sun; Dongjie Zhao; Chong Wang; Ying Zhao

    2014-01-01

    The automatic sapling grafting methods and grafting robot technologies are not comprehensively studied despite the fact that they are urgently required in practice. For this reason, a sapling grafting robot is developed to implement automatic grafting for saplings. The developed grafting robot includes clipping mechanism, moving mechanism, cutting mechanism, binding mechanism, and Arduino MCU based control system, which is capable of clipping, moving, positioning, cutting, grafting, and bindi...

  13. Bone Grafting the Cleft Maxilla

    Science.gov (United States)

    ... systemic disease such as diabetes, or has poor oral hygiene, the risk that the graft may fail increases even more. Once the bone graft has been placed, there are three options that ... replacement (dental bridge); or 3) dental metallic bone implants. The ...

  14. Polyether/Polyester Graft Copolymers

    Science.gov (United States)

    Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

    1986-01-01

    Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

  15. Collapse of grafted polyelectrolyte layer

    OpenAIRE

    Borisov, O.; Birshtein, T.; Zhulina, E.

    1991-01-01

    The theory describing chain conformation in a planar layer of grafted polyelectrolyte (polyampholyte) molecules and the conformational transition related to the collapse of this layer caused by the decrease in solvent strenght is developed. Depending on the values of the layer parameters (grafting and charge densities) this transition may occur as a continuous (cooperative) or as a first order phase transition.

  16. Surface modification of cellulose by PCL grafts

    Energy Technology Data Exchange (ETDEWEB)

    Paquet, Olivier; Krouit, Mohammed; Bras, Julien [Laboratoire de Genie des Procedes Papetiers (UMR 5518 CNRS-CTP-INPG), Grenoble INP-Pagora, 461 Rue de la papeterie, F-38402 St Martin d' Heres (France); Thielemans, Wim [Driving Innovation in Chemistry and Chemical Engineering (DICE), School of Chemistry and Process and Environmental Research Division - Faculty of Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom); Belgacem, Mohamed Naceur, E-mail: Naceur.Belgacem@efpg.inpg.fr [Laboratoire de Genie des Procedes Papetiers (UMR 5518 CNRS-CTP-INPG), Grenoble INP-Pagora, 461 Rue de la papeterie, F-38402 St Martin d' Heres (France)

    2010-02-15

    Two cellulosic substrates (microcrystalline cellulose, MCC, and bleached kraft softwood pulps, BSK) were grafted by polycaprolactone (PCL) chains with different molecular weights, following a three-step procedure using non-swelling conditions in order to limit the reaction to their surface. First, one of the two OH PCL ends was blocked by phenyl isocyanate and the reaction product (adduct 1) was subsequently reacted with 2,4-toluene diisocyanate (adduct 2) to provide it with an NCO function, capable of reacting with cellulose. The ensuing PCL-grafted cellulosic materials were characterized by weight gain, elemental analysis, contact angle measurements, attenuated total reflexion-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and biodegradation tests. The modification was proven to occur by the presence of nitrogen atoms in the elemental analysis tests and XPS spectra of modified and soxhlet-extracted cellulose. The contact angle measurements have also shown that the surface became as hydrophobic as PCL itself. The polar component of the surface energy of cellulosic substrates before treatment was found to be about 32 and 10 mJ m{sup -2}, for MCC and BSK, respectively. This value vanished to practically zero after grafting with different PCLs. The strategy proposed in the present work is original since, to the best of our knowledge, this paper reports for the first time the chemical 'grafting onto' of the cellulose surface by PCL macromolecular structures, with the aim of obtaining fibre-matrix co-continuous fully sustainable and biodegradable composite materials.

  17. Grafting techniques for Peyronie's disease.

    Science.gov (United States)

    Hatzichristodoulou, Georgios

    2016-06-01

    Peyronie's disease (PD) is a benign fibrotic condition of the penile tunica albuginea. PD can be associated with penile pain, curvature, shortening, and erectile dysfunction (ED). The predominant and most bothersome symptom in affected patients is penile curvature, which can lead to inability to have sexual intercourse. In such cases, surgical correction of the curvature may be required. Plication techniques to correct curvature can cause penile shortening and therefore are generally reserved for curvatures 60°, short penis, or hourglass deformity. Patients scheduled for grafting surgery are required to have satisfactory erectile rigidity preoperatively. There are various grafting materials that can be used for closure of the tunica albuginea defect following plaque incision/excision. Both autologous and non-autologous grafts have been used for PD reconstructive surgery, and each graft has its advantages and disadvantages. Novel grafting materials are presented and discussed in this review. A major advantage of the available "off-the-shelf" grafts is that there is no harvesting from a donor site and, thus, morbidity is reduced, and operative times are minimized. Further investigations in regard to tissue-engineered grafts to improve surgical handling and postoperative outcomes are ongoing. Surgeon experience, careful patient selection, patient preference and type of penile deformity affect the choice of graft. This review summarizes the literature within the past 5 years regarding grafting techniques in PD. Surgical outcomes and limitations of grafting techniques are reported. A major objective of this review is dedicated to preoperative considerations and indications for grafting procedures, with the aim to improve surgical outcomes and increase patient satisfaction. Proper postoperative management of patients after incision/excision and grafting is important to avoid early and long-term complications and unwanted outcomes. This review provides an overview of

  18. Electron beam grafting of polymers

    International Nuclear Information System (INIS)

    Electron beam (EB) grafting has been a well known technique for modifying the surfaces of materials for many years. Commercial implementation has been quite successful in a few, narrow niche markets. Irradiation grafting is being used to control ion flow through battery separator membranes, to modify the hydrophilic and hydrophobic properties of semi-permeable membranes and non-woven fabrics, to enhance the bio-compatibility of materials used in the medical device area, and to impart release properties to films and papers. The use of grafting to modify the bulk properties of materials has not as yet emerged as a widely accepted commercial practice. The development of lower voltage, more cost-effective self-shielded electron beam equipment presents opportunities for enhanced commercial development. The technology used in grafting is very specific to the selection of the base polymer and to the choice of the graft monomers. Different combinations can yield vastly different performance properties

  19. Penentuan Derajat Grafting Dan Fraksi Gel Dari Polipropilena Terdegradasi Yang Difungsionalisasikan Dengan Maleat Anhidrida

    OpenAIRE

    Hidayani, Tengku Rachmi

    2011-01-01

    A research has been done about determination grafting degree and gel fraction on functionalization of degraded polypropylene with maleic anhydride. Degradation reaction is done with reactive processing technique in internal mixer on temperature 170 o C. Composition of polypropylene : benzoyl peroxide which is 90% : 10%. Grafting reaction is done on temperature 160oC. Composition of degraded polypropylene : maleic anhydride : benzoyl peroxide which is : (95%:3%:2%), (92%:6%:2%), (89%:9%:2%), (...

  20. Composites

    Science.gov (United States)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  1. Preirradiation grafting of acrylonitrile onto polypropylene monofilament for biomedical applications: I. Influence of synthesis conditions

    International Nuclear Information System (INIS)

    Graft polymerization of acrylonitrile onto polypropylene (PP) monofilament was carried out by a preirradiation method using a 6Co gamma radiation source. The influence of synthesis conditions, such as preirradiation dose, reaction time, monomer concentration, reaction temperature and additives was determined. The grafting was considerably influenced by the instantaneous swelling of the monofilament in the reaction mixture during the course of the grafting process. The order of dependence of the rate of grafting on monomer concentration was found to be 1.04. The nature of the medium of the grafting and the additives had profound influence over the grafting reaction. The accelerative effects of solvent medium on the grafting were higher in methylethyl ketone (MEK) and dimethylformamide (DMF) as compared to methanol. At the same time, partial replacement of DMF with water led to acceleration in the grafting with peak maxima at 20% solvent composition. The addition of a small amount of sulfuric acid to the reaction mixture also resulted in a significant acceleration of the degree of grafting

  2. Development of EPDM based thermoplastic elastomers for oil resistant applications: optimization of radiation grafting parameters

    International Nuclear Information System (INIS)

    Full text: Ethylene-propylene diene terpolymer (EPDM) is currently among the most industrially useful elastomers because of its certain unique properties like excellent heat resistance, resistance towards ozone deterioration, high impact strength. However EPDM has a serious drawback of weak adhesion properties and tendency to swell in contact with paraffin oil and aromatic hydrocarbons. Blending EPDM with suitable polar elastomers or grafting polar polymer chains onto EPDM is an easy method to overcome this drawback. Radiation grafting of Acrylonitrile (ACN) on EPDM provides an easy and effective method of incorporating ACN uniformly on the EPDM backbone. Grafting of ACN on EPDM is expected to result grafted copolymer with better oil resistance, hardness and better compatibility with polar polymer matrices. In the present study radiation induced grafting of ACN onto EPDM rubber film was investigated by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, types of solvents and monomer content on extent of grafting was studied. The solvent composition of Acetone:CCl4 (20:80) was found to be the optimum mixture which resulted in highest degree of grafting. It was found that the degree of grafting increases with radiation dose, monomer content and decreases with dose rate

  3. Radiation-grafting of N-vinylimidazole onto silicone rubber for antimicrobial properties

    International Nuclear Information System (INIS)

    Poly(N-vinylimidazole) (PVIm) was grafted $numbers onto silicone rubber (SR) with the aim of providing antimicrobial properties. The grafting was carried out by means of gamma rays using the direct method. The influence on the grafting yield of absorbed dose, monomer concentration, addition of FeSO4 salt, composition and type of solvent (H2O, MeOH, THF, and acetone) was investigated. Grafts onto SR between 10% and 90% were obtained at doses from 20 to 100 kGy and a dose rate 10.9 kGy h−1; grafting yield increased with monomer concentration and dose. The new graft copolymers were confirmed by Fourier transform infrared spectroscopy (FT-IR). Differential scanning calorimeter (DSC) showed glass transition at 149 and 159 °C for 38% and 88% grafting respectively. Thermogravimetry analysis (TGA) presented two decomposition temperatures for SR-g-VIm at 380 (PVIm) and 440 °C (SR). SR-g-VIm showed antibacterial activity against Pseudomonas aeruginosa. - Highlights: • We modify medical grade silicone rubber with N-vinylimidazole. • We examine reaction conditions in order to carry out the grafting process. • Modified silicone rubber presents antibacterial performance. • Grafting of N-vinylimidazole may be suitable for development of medical devices with antimicrobial activity

  4. Percutaneous Intervention of Sequential Coronary Venous Graft

    OpenAIRE

    Zeki DOGAN; Karabulut, Ahmet; Uzunlar, Bulent

    2014-01-01

    We present a case with coronary bypass grafts in which venous graft was anastomosed to obtuse marginal (OM) 1 and OM2 branches sequentially. We performed percutaneous intervention to the proximal circumflex (CX), OM1, and bridging segment of the venous graft. Finally, bridging segment of the venous graft began to function as a CX body extending between the OM1 and OM2.

  5. Are Aortic Stent Grafts Safe in Pregnancy?

    OpenAIRE

    Nader Khandanpour; Mehta, Tapan A.; Adiseshiah, M; Meyer, Felicity J.

    2015-01-01

    Aortic stent grafts are increasingly used to treat aortic aneurysms and also other aortic pathologies. The safety of aortic stent grafts in pregnancy has never been studied or reported. We report on two cases of aortic stent grafts in pregnant women and discuss the effect of pregnancy on these aortic stent grafts.

  6. Tunable Pickering emulsions with polymer-grafted lignin nanoparticles (PGLNs).

    Science.gov (United States)

    Silmore, Kevin S; Gupta, Chetali; Washburn, Newell R

    2016-03-15

    Lignin is an abundant biopolymer that has native interfacial functions but aggregates strongly in aqueous media. Polyacrylamide was grafted onto kraft lignin nanoparticles using reversible addition-fragmentation chain transfer (RAFT) chemistry to form polymer-grafted lignin nanoparticles (PGLNs) that tune aggregation strength while retaining interfacial activities in forming Pickering emulsions. Polymer graft density on the particle surface, ionic strength, and initial water and cyclohexane volume fractions were varied and found to have profound effects on emulsion characteristics, including emulsion volume fraction, droplet size, and particle interfacial concentration that were attributed to changes in lignin aggregation and hydrophobic interactions. In particular, salt concentration was found to have a significant effect on aggregation, zeta potential, and interfacial tension, which was attributed to changes in solubility of both the kraft lignin and the polyacrylamide grafts. Dynamic light scattering, UV-vis spectroscopy, optical microscopy, and tensiometry were used to quantify emulsion properties and nanoparticle behavior. Under all conditions, the emulsions exhibited relatively fast creaming but were stable against coalescence and Ostwald ripening for a period of months. All emulsions were also oil-in-water (o/w) emulsions, as predicted by the Bancroft rule, and no catastrophic phase inversions were observed for any nanoparticle compositions. We conclude that lower grafting density of polyacrylamide on a lignin core resulted in high levels of interfacial activity, as characterized by higher concentration at the water-cyclohexane interface with a corresponding decrease in interfacial tension. These results indicate that the interfacial properties of polymer-grafted lignin nanoparticles are primarily due to the native hydrophobic interactions of the lignin core. These results suggest that the forces that drive aggregation are also correlated with interfacial

  7. Radioinduced grafting of acrylic acid on expanded polystyrene matrices

    International Nuclear Information System (INIS)

    The unfixed surface radioactive contamination for low energy β radionuclides (3H and 14C) is determined by wiping the checked surfaces with sponge of absorbent materials. The activity built up by this sponge is measured by a liquid scintillator spectrometer. In this work, a method of obtaining sponges of expanded polystyrene with hydrophobic surface by radioinduced grafting of the acrylic acid is presented. These sponges have diameters of 28 mm, thicknesses of 1.5 - 2 mm and density of 22 mg/cm3. The samples were immersed in a grafting solution with the following composition: acrylic acid 30%, Cu SO4 1%; water 69% which were deeply impregnated in repeated operations under vacuum and pressure conditions, respectively. Finally, the samples were exposed to γ radiation emitted by a 60Co source (IETI 10 000 - IFIN-HH). The dose rates were 0.3, 0.5 and 1 Mrad/h. The range of the absorbed doses was 1 - 25 Mrad. The yields of radiochemical grafting have been determined by gravimetric, spectrophotometric and radiometric methods. The grafting agent used was 3H labelled acrylic acid. The solvation capacity and the quenching characteristics of the grafted sponges in liquid scintillators, as well as the sampling yields have been analyzed as function of irradiation procedure and the percentage of grafted acrylic fragments. The superficial grafting of the acrylic acid has been carried out by the mentioned technique, leading to the increase of the wiping efficiency of the unfixed surface contaminating activity, without changes of polymer solubility in liquid scintillators and without the perturbation of the radioactivity detection process. (authors)

  8. Radiation grafting of synthetic fibres

    International Nuclear Information System (INIS)

    The dose-response relationships were studied in radiation-induced grafting copolymerization. Polyester textile fabric samples were irradiated with electrons from a Van de Graaff type accelerator under nitrogen atmosphere. Radiation doses ranged within 10 and 150 kGy. An 80% acrylic acid solution was used as the monomer while a 0.1% Mohr's salt solution was used as the inhibitor of acrylic acid homopolymerization. Grafting proceeded at 95 degC in a time interval of 10 mins. It was found that at constant time and temperature conditions the initially grafting grade rapidly increased while at values exceeding 20% only relatively small changes were recorded. The grafting grade was also found to favourably alter some properties of the modified materials, such as moisture content and tensile strength. (Z.M.)

  9. Study on superhydrophobic surfaces of octanol grafted electrospun silica nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Long-Yue [Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Yanbian University, Yanji 133002 (China); Department of Chemical Engineering, College of Engineering, Yanbian University, 977 Gongyuan Road, Yanji 133002 (China); Han, Shunyu; Jiang, Nanzhe [Department of Chemical Engineering, College of Engineering, Yanbian University, 977 Gongyuan Road, Yanji 133002 (China); Meng, Wan, E-mail: mengw@ybu.edu.cn [Department of Chemical Engineering, College of Engineering, Yanbian University, 977 Gongyuan Road, Yanji 133002 (China)

    2014-12-15

    In this work, superhydrophobic surfaces were successfully prepared by grafting of octanol on the surface of electrospun silica nanofibers (SNFs). The chemical compositions and microstructures of the prepared SNFs surfaces were investigated by using N{sub 2} full isotherms, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and contact angle measurements. The results indicate that the surface of SNFs changed from being superhydrophilic to superhydrophobic by octanol surface grafting. The contact angle of the octanol-grafted SNFs was close to 150.2° because their surface was modified by –(CH{sub 2}){sub 6}–CH{sub 3} groups. The 3D network of SNFs networks and the low surface energy of the alkyl side chains played important roles in creating the superhydrophobic surface of the SNFs. - Highlights: • Superhydrophobic surface was prepared from electrospinning SNFs and by grafting octanol on their surface. • The surface of SNFs changed from superhydrophilic to superhydrophobic. • The CA of MSNFs became 150.2° because of interactions between grafted octyl groups.

  10. Study on superhydrophobic surfaces of octanol grafted electrospun silica nanofibers

    International Nuclear Information System (INIS)

    In this work, superhydrophobic surfaces were successfully prepared by grafting of octanol on the surface of electrospun silica nanofibers (SNFs). The chemical compositions and microstructures of the prepared SNFs surfaces were investigated by using N2 full isotherms, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and contact angle measurements. The results indicate that the surface of SNFs changed from being superhydrophilic to superhydrophobic by octanol surface grafting. The contact angle of the octanol-grafted SNFs was close to 150.2° because their surface was modified by –(CH2)6–CH3 groups. The 3D network of SNFs networks and the low surface energy of the alkyl side chains played important roles in creating the superhydrophobic surface of the SNFs. - Highlights: • Superhydrophobic surface was prepared from electrospinning SNFs and by grafting octanol on their surface. • The surface of SNFs changed from superhydrophilic to superhydrophobic. • The CA of MSNFs became 150.2° because of interactions between grafted octyl groups

  11. Interventions in Infrainguinal Bypass Grafts

    International Nuclear Information System (INIS)

    The interventional radiologist plays an important role in the detection and prevention of infrainguinal bypass failure. Early detection and evaluation of flow-limiting lesions effectively preserve graft (venous bypass and polyester or expanded polytetrafluoroethylene bypass) patency by identifying stenoses before occlusion occurs. Delay in treatment of the at-risk graft may result in graft failure and a reduced chance of successful revascularization. For this reason, surveillance protocols form an important part of follow-up after infrainguinal bypass surgery. As well as having an understanding of the application of imaging techniques including ultrasound, MR angiography, CT angiography and digital subtraction angiography, the interventional radiologist should have detailed knowledge of the minimally invasive therapeutic options. Percutaneous transluminal angioplasty (PTA), or alternatively cutting balloon angioplasty, is the interventional treatment of choice in prevention of graft failure and occlusion. Further alternatives include metallic stent placement, fibrinolysis, and mechanical thrombectomy. Primary assisted patency rates following PTA can be up to 65% at 5 years. When the endovascular approach is unsuccessful, these therapeutic options are complemented by surgical procedures including vein patch revision, jump grafting, or placement of a new graft

  12. FAS grafted superhydrophobic ceramic membrane

    International Nuclear Information System (INIS)

    The hydrophobic properties of γ-Al2O3 membrane have been obtained by grafting fluoroalkylsilane (FAS) on the surface of the membrane. The following grafting parameters were studied: the eroding time of the original membrane, the grafting time, the concentration of FAS solution and the multiplicity of grafting. Hydrophobicity of the membranes was characterized by contact angle (CA) measurement. The thermogravimetric analysis (TGA) was used to investigate the weight loss process (25-800 deg. C) of the fluoroalkylsilane grafted on Al2O3 powders under different grafting conditions. The morphologies of the membranes modified under different parameters were examined by field emission scanning electron microscopy (FE-SEM) and the surface roughness (Ra) was measured using white light interferometers. A needle-like structure was observed on the membrane surface after modification, which causes the change of Ra. On the results above, we speculated a model to describe the reaction between FAS and γ-Al2O3 membrane surface as well as the formed surface morphology.

  13. Multimodal imaging of vascular grafts using time-resolved fluorescence and ultrasound

    Science.gov (United States)

    Fatakdawala, Hussain; Griffiths, Leigh G.; Wong, Maelene L.; Humphrey, Sterling; Marcu, Laura

    2015-02-01

    The translation of engineered tissues into clinic requires robust monitoring of tissue development, both in vitro and in vivo. Traditional methods for the same are destructive, inefficient in time and cost and do not allow time-lapse measurements from the same sample or animal. This study reports on the ability of time-resolved fluorescence and ultrasound measurements for non-destructive characterization of explanted tissue engineered vascular grafts. Results show that TRFS and FLIm are able to assess alterations in luminal composition namely elastin, collagen and cellular (hyperplasia) content via changes in fluorescence lifetime values between normal and grafted tissue. These observations are complemented by structural changes observed in UBM pertaining to graft integration and intimal thickness over the grafted region. These results encourage the future application of a catheter-based technique that combines these imaging modalities for non-destructive characterization of vascular grafts in vivo.

  14. Preparation and Grafting Functionalization of Self-Assembled Chitin Nanofiber Film

    Directory of Open Access Journals (Sweden)

    Jun-ichi Kadokawa

    2016-07-01

    Full Text Available Chitin is a representative biomass resource comparable to cellulose. Although considerable efforts have been devoted to extend novel applications to chitin, lack of solubility in water and common organic solvents causes difficulties in improving its processability and functionality. Ionic liquids have paid much attention as solvents for polysaccharides. However, little has been reported regarding the dissolution of chitin with ionic liquids. The author found that an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr, dissolved chitin in concentrations up to ~4.8 wt % and the higher contents of chitin with AMIMBr gave ion gels. When the ion gel was soaked in methanol for the regeneration of chitin, followed by sonication, a chitin nanofiber dispersion was obtained. Filtration of the dispersion was subsequently carried out to give a chitin nanofiber film. A chitin nanofiber/poly(vinyl alcohol composite film was also obtained by co-regeneration approach. Chitin nanofiber-graft-synthetic polymer composite films were successfully prepared by surface-initiated graft polymerization technique. For example, the preparation of chitin nanofiber-graft-biodegradable polyester composite film was achieved by surface-initiated graft polymerization from the chitin nanofiber film. The similar procedure also gave chitin nanofiber-graft-polypeptide composite film. The surface-initiated graft atom transfer radical polymerization was conducted from a chitin macroinitiator film derived from the chitin nanofiber film.

  15. Revascularização miocárdica com enxerto composto de artéria torácica interna esquerda em Y: análise de fluxo sangüíneo Myocardial revascularization surgery using composite Y-graft of the left internal thoracic artery: blood flow analysis

    Directory of Open Access Journals (Sweden)

    José Glauco Lobo Filho

    2004-03-01

    the LADA and another artery from the LCAS. The angiographic study showed graft patency in all patients from both groups. The following parameters were used: systolic flow (SF, diastolic flow, total flow, total flow in stress/total flow at rest ratio (TFS/TFR, systolic peak velocities (SPV, diastolic peak velocities and systolic peak velocity/diastolic peak velocity ratio. RESULTS: All analysed parameters were considered statistically significant, except SF, TFS/TFR and SPV. CONCLUSIONS: We concluded that in the same conditions and methodology, the LITA flow in the composite graft (group B is higher than in the free graft (group A, which shows the great flow adaptability of LITA to respond to flow demand.

  16. Ionic membranes obtained by radiation-induced graft copolymerization, I-preparation. Vol. 3

    International Nuclear Information System (INIS)

    A study has been made on the preparation of ionic membranes by radiation-induced graft copolymerization of acrylic acid (AAC) onto low density polyethylene (LDPE) films. The Suitable conditions at which the grafting proceeds homogeneously were determined. To minimize the homo polymerization of AAC during irradiation process different types of inhibitors were investigated to find that the addition of Fe Cl3 (1.5 Wt%) effectively reduced such process when compared with other inhibitors used. The suitable diluent for this grafting system is found to be distilled water, methanol and methanol water mixture. The effect of diluent mixture composition, irradiation time, addition of mineral or organic acid and metal chlorides on the grafting yield and its homogeneity in the graft copolymer was determined. It was observed that the grafting yield increased as the content of water increased in MeOH/H2 O mixture. The addition of oxalic acid to the reaction medium enhanced the grafting process, however, the addition of HCl or H2 S O4 resulted in a more homogeneous grafting. The same effect was also observed when metal salts; namely N H4 Cl, NaCl and Cu Cl2 were added and resulted in homogeneous grafted membranes. The swelling and permeability of the grafted films prepared were also investigated. Results obtained in this study showed a great promise for the possible practical use of such prepared graft copolymers as a good hydrophilic membrane. The possibility of its use as an ion-exchange membrane for metal waste will be considered.4 figs., 5 tabs

  17. Studies on surface graft polymerization of acrylic acid onto PTFE film by remote argon plasma initiation

    International Nuclear Information System (INIS)

    The graft polymerization of acrylic acid (AAc) was carried out onto poly(tetrafluoroethylene) (PTFE) films that had been pretreated with remote argon plasma and subsequently exposed to oxygen to create peroxides. Peroxides are known to be the species responsible for initiating the graft polymerization when PTFE reacts with AAc. We chose different parameters of remote plasma treatment to get the optimum condition for introducing maximum peroxides (2.87 x 10-11 mol/cm2) on the surface. The influence of grafted reaction conditions on the grafting degree was investigated. The maximum grafting degree was 25.2 μg/cm2. The surface microstructures and compositions of the AAc grafted PTFE film were characterized with the water contact angle meter, Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Contact angle measurements revealed that the water contact angle decreased from 108o to 41o and the surface free energy increased from 22.1 x 10-5 to 62.1 x 10-5 N cm-1 by the grafting of the AAc chains. The hydrophilicity of the PTFE film surface was greatly enhanced. The time-dependent activity of the grafted surface was better than that of the plasma treated film

  18. Rapid, facile microwave-assisted synthesis of xanthan gum grafted polyaniline for chemical sensor.

    Science.gov (United States)

    Pandey, Sadanand; Ramontja, James

    2016-08-01

    Grafting method, through microwave radiation procedure is extremely productive in terms of time consumption, cost effectiveness and environmental friendliness. In this study, conductive and thermally stable composite (mwXG-g-PANi) was synthesized by grafting of aniline (ANi) on to xanthan gum (XG) using catalytic weight of initiator, ammonium peroxydisulfate in the process of microwave irradiation in an aqueous medium. The synthesis of mwXG-g-PANi were confirm by FTIR, XRD, TGA, and SEM. The influence of altering the microwave power, exposure time of microwave, concentration of monomer and the amount of initiator of graft polymerization were studied over the grafting parameters, for example, grafting percentage (%G) and grafting efficiency (%E). The maximum %G and %E achieved was 172 and 74.13 respectively. The outcome demonstrates that the microwave irradiation strategy can increase the reaction rate by 72 times over the conventional method. Electrical conductivity of XG and mwXG-g-PANi composite film was performed. The fabricated grafted sample film were then examined for the chemical sensor. The mwXG-g-PANi, effectively integrated and handled, are NH3 sensitive and exhibit a rapid sensing in presence of NH3 vapor. Chemiresistive NH3 sensors with superior room temperature sensing performance were produced with sensor response of 905 at 1ppb and 90% recovery within few second. PMID:27118045

  19. Pengaruh Konsentrasi Maleat Anhidrida Terhadap Derajat Grafting Maleat Anhidrida Pada Polipropilena Terdegradasi Dengan Inisiator Benzoil Peroksida

    OpenAIRE

    Nasution, Reni Silvia

    2011-01-01

    A research has been conducted on effect of maleic anhydride concentration on the grafting degree in degradated of polypropylene with inisiator benzoyl peroxide. Grafting reaction was done by reactive process technique in internal mixer at 165oC with variation of composition in the weigh ratio of PP:MA:BPO is 97:1:2, 95:3:2, 92:6:2, 89:9:2, and 86:12:2 . the quantity of grafted MA onto PP molecules was determined by titration method and the modified polymer samples were characte...

  20. Vascularized osseous graft for scaphoid

    International Nuclear Information System (INIS)

    The most commonly used technique for treatment of pseudo-arthrosis of the scaphoid is osteo-synthesis with Kirschnet wires and cortical sponge grafts. Results reported by different teams using this procedure show no more than 90% osseous consolidation, especially in cases where vascularisation of the proximal fragment of the scaphoid is compromised. Here we present a series of ten cases of pseudo-arthrosis of the scaphoid, treated using a new surgical technique involving a vascularized osseous graft of the distal radius. Using this procedure we obtained 100% consolidation, with no complications either during the procedure or immediately post-operatively. Patients returned to work in week 15 on average. In 4 cases we observed discomfort in the area of the scar, which was successfully treated using local cortisone injection. The results obtained are very similar to those seen in the literature on the different techniques for vascularized osseous grafts for pseudo-arthrosis of the scaphoid

  1. Increasing the Thermal Conductivity of Graphene-Polyamide-6,6 Nanocomposites by Surface-Grafted Polymer Chains: Calculation with Molecular Dynamics and Effective-Medium Approximation.

    Science.gov (United States)

    Gao, Yangyang; Müller-Plathe, Florian

    2016-02-25

    By employing reverse nonequilibrium molecular dynamics simulations in a full atomistic resolution, the effect of surface-grafted chains on the thermal conductivity of graphene-polyamide-6.6 (PA) nanocomposites has been investigated. The interfacial thermal conductivity perpendicular to the graphene plane is proportional to the grafting density, while it first increases and then saturates with the grafting length. Meanwhile, the intrinsic in-plane thermal conductivity of graphene drops sharply as the grafting density increases. The maximum overall thermal conductivity of nanocomposites appears at an intermediate grafting density because of these two competing effects. The thermal conductivity of the composite parallel to the graphene plane increases with the grafting density and grafting length which is attributed to better interfacial coupling between graphene and PA. There exists an optimal balance between grafting density and grafting length to obtain the highest interfacial and parallel thermal conductivity. Two empirical formulas are suggested, which quantitatively account for the effects of grafting length and density on the interfacial and parallel thermal conductivity. Combined with effective medium approximation, for ungrafted graphene in random orientation, the model overestimates the thermal conductivity at low graphene volume fraction (f 10%). For unoriented grafted graphene, the model matches the experimental results well. In short, this work provides some valuable guides to obtain the nanocomposites with high thermal conductivity by grafting chain on the surface of graphene. PMID:26800434

  2. Types of Coronary Artery Bypass Grafting

    Science.gov (United States)

    ... best option for you based on your needs. Traditional Coronary Artery Bypass Grafting Traditional CABG is used when at least one major ... Grafting This type of CABG is similar to traditional CABG because the chest bone is opened to ...

  3. Prevention of primary vascular graft infection with silver-coated polyester graft in a porcine model

    DEFF Research Database (Denmark)

    Gao, H; Sandermann, J; Prag, J; Lund, L; Lindholt, Jes S.

    2010-01-01

    To evaluate the efficacy of a silver-coated vascular polyester graft in the prevention of graft infection after inoculation with Staphylococcus aureus in a porcine model.......To evaluate the efficacy of a silver-coated vascular polyester graft in the prevention of graft infection after inoculation with Staphylococcus aureus in a porcine model....

  4. Distribution of the degrees of grafting in graft polymers

    Czech Academy of Sciences Publication Activity Database

    Netopilík, Miloš; Janata, Miroslav; Kratochvíl, Pavel

    Gargnano : EPF , 2010. s. 58. [EUPOC 2010 - Europolymer Conference, Hierarchically Structured Polymers. 30.05.2010-04.06.2010, Gargnano] R&D Projects: GA AV ČR IAA400500703 Institutional research plan: CEZ:AV0Z40500505 Keywords : grafting * molecular weight distribution Subject RIV: CD - Macromolecular Chemistry

  5. Use of porous high-density polyethylene grafts in open rhinoplasty: no infectious complication seen in spreader and dorsal grafts

    OpenAIRE

    Mohammadi, Shabahang; Mohseni, Mohammad; Eslami, Masoumeh; Arabzadeh, Hessein; Eslami, Morteza

    2014-01-01

    Objective The aim of this study is to use porous high-density polyethylene grafts (Medpor) in open rhinoplasty and then assess complication rate and aesthetic outcomes. Methods In a prospective cohort study, we performed open rhinoplasty and employed Medpor as rhinoplasty grafts. Then we compared their complication rate. Results In a total of 64 patients, 84 Medpor grafts -38 dorsal grafts, 23 strut grafts, 8 rim grafts, 5 button grafts and 10 spreader grafts – were utilized. Moreover, 5septa...

  6. Grafting of Glycidylmethacrylate onto HD-PE by reactive injection moulding

    International Nuclear Information System (INIS)

    In this work, the free radical grafting of Glycidylmethacrylate (GMA) onto HD-PE, initiated by Di-tert-butyl-peroxide and Di(tert -butylperoxy)-2,5-dimethylhex-3-ine, was studied. Experiments were carried out in solution with 1,2-Dichlorobenzene as solvent and by reactive injection moulding. Monomer- and initiator-concentrations were varied and the influence of these parameters on the grafting yields and the content of residual monomer and homopolymer of GMA were studied. Additionally the mechanical and thermal properties of the grafting products were determined. Grafting yields were analyzed by FT-IR-spectroscopy, the residual monomer content by TGA, and the mechanical and thermal properties by means of tensile tests, TGA, and DSC. It was found, that the compositions of the grafted products were subject to change in a wide range depending on the initial concentrations of monomer and initiator. Grafting yields could be raised by increasing the initial content of peroxide as well as of monomer, the addition of high monomer concentrations lead to a decrease of the grafting yields. The amount of homopolymer and monomer residuals was varied by varying the monomer- and initiator-concentrations, too. Consequently the Youngs-Modulus, crystallinity, and the melting and degradation behaviour varied as well as function of the composition, whereby the content of monomer residuals showed the highest impact on the mechanical properties, while the crystallinity was subject to change as a function of the grafting yield. This was most probably due to variations in length and the distribution of the grafted chains, which was shown through IR-spectroscopy. The results indicated a significant impact on the mechanical and thermal properties by the formation of crosslinks between the PE-chains and β-cleavage reactions. (author)

  7. Multimodality imaging of coronary artery bypass grafts

    OpenAIRE

    Salm, Liesbeth Pauline

    2006-01-01

    This thesis describes multiple imaging modalities to examine coronary artery bypass grafts, and the research which was performed to further develop noninvasive imaging techniques to detect stenoses in native coronary arteries and bypass grafts in patients who experienced recurrent chest pain after coronary artery bypass grafting (CABG).

  8. Development of Novel Absorbents and Membranes by Radiation-Induced Grafting for Selective Purposes

    International Nuclear Information System (INIS)

    The direct radiation grafting technique was used to graft glycidyl methacrylate (GMA) monomer containing epoxy ring, onto polypropylene fibres. The ring opening of the epoxy ring in GMA by different amino groups was studied to introduce various chelating agents. Some properties of grafted fibres were studied and the possibility of its practical use for water treatment from iron and manganese metals was investigated. The radiation initiated grafting of acrylic acid (AAc) or acrylamide (AAm) monomers onto poly(vinyl alcohol) (PVA), a 2-acrylamide-2-methyl propane sulfonic acid (AMPS) polymer was studied. Cationic/anionic membranes were also prepared by radiation-induced grafting of styrene/methacrylic acid (Sty/MAA) binary monomers onto LDPE films. To impart reactive cationic/anionic characters in the grafted membranes, sulfonation and alkaline treatments for styrene and carboxylic acid groups, respectively, were carried out. The possibility of their applications in the selective removal of some heavy metals was studied. The prepared grafted materials had a great ability to recover the metal ions such as: Ni2+, Co2+, Cu2+, Cd2+, Mg2+, Zn2+, Mn2+ and Cr3+ from their solutions. It was found that AMPS content in the grafted copolymers is the main parameter for the selectivity of the copolymer towards metal ions. The higher the AMPS content the higher the selectivity towards Co and Ni ions. In case of LDPE-g-P(STY/MAA), the sulfonation and alkaline treatments are the most effective methods to influence metal absorption and swelling behaviour of the prepared membranes. Graft composition, dose and pH have also a great influence on the membrane characteristics and applicability in wastewater treatments from heavy and toxic metals. Results revealed that the prepared grafted materials with different functionalized groups are promising as ion selective membranes and could be used for wastewater treatment. (author)

  9. STUDY OF GRAFT SITES IN EPOXY GRAFT COPOLYMERS BY QUANTUM CHEMISTRY CALCULATIONS

    Institute of Scientific and Technical Information of China (English)

    Song Chen; Xiao-yu Li

    2009-01-01

    Exploration and characterization of grafting productions by experimental methods are often cumbersome or sometimes impossible. Therefore, quantum chemistry calculations were performed to characterize the graft sites of epoxy resin. According to the Gibbs free energy criterion of the second law of thermodynamic, the reported graft sites were confirmed, and more important, some unreported graft sites were found. In addition, method of increasing the number of graft sites was studied in this article.

  10. The Right Gastroepiploic Artery Graft for Coronary Artery Bypass Grafting: A 30-Year Experience

    Science.gov (United States)

    Suma, Hisayoshi

    2016-01-01

    Throughout its 30-year history, the right gastroepiploic artery (GEA) has been useful for in situ grafts in coronary artery bypass grafting (CABG). The early graft patency rate is high, and the late patency rate has improved by using the skeletonized GEA graft and proper target selection, which involves having a target coronary artery with a tight >90% stenosis. Total arterial revascularization with the internal thoracic artery and GEA grafts is an option for achieving better outcomes from CABG procedures. PMID:27525230

  11. Grafting of Polycaprolactone on Oxidized Nanocelluloses by Click Chemistry

    Directory of Open Access Journals (Sweden)

    Claude Daneault

    2013-03-01

    Full Text Available The main objective of this work is the grafting of polycaprolactone diol (PCL on the surface of oxidized nanocelluloses (ONC in order to enhance the compatibility between the hydrophilic cellulose nanofibres and the hydrophobic polymer matrix. This grafting was successfully realized with a new strategy known as click chemistry. In this context, the oxidized nanocelluloses bearing alkyl groups (ONC-PR were prepared by reacting amino groups of propargylamine (PR with carboxyl groups of ONC. In parallel, PCL was converted into azido-polycaprolactone (PCL-N3 in two steps: (i tosylation of polycaprolactone (PCL-OTs and (ii conversion of PCL-OTs into PCL-N3 by nucleophilic displacement using sodium azide. Finally, ONC-PR was reacted with PCL-N3 in heterogeneous conditions through click chemistry in order to prepare polycaprolactone grafted oxidized nanocellulose (ONC-g-PCL, which could be suitable for improving the interfacial adhesion in the composite materials. The grafted samples were characterized by transmission electron microscopy and by Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS and Carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR spectroscopic techniques.

  12. Markers of primary graft dysfunction

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention relates to methods for diagnosing transplant rejection, or a condition associated with transplant rejection, such as, primary graft dysfunction in a subject, to antigen probe arrays for performing such a diagnosis, and to antigen probe sets for generating such arrays....

  13. Polyether-polyester graft copolymer

    Science.gov (United States)

    Bell, Vernon L. (Inventor)

    1987-01-01

    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  14. Vascular grafting strategies in coronary intervention

    Science.gov (United States)

    Knight, Darryl; Gillies, Elizabeth; Mequanint, Kibret

    2014-06-01

    With the growing need for coronary revascularizations globally, several strategies to restore blood flow to the heart have been explored. Bypassing the atherosclerotic coronary arteries with autologous grafts, synthetic prostheses and tissue-engineered vascular grafts continue to be evaluated in search of a readily available vascular graft with clinically acceptable outcomes. The development of such a vascular graft including tissue engineering approaches both in situ and in vitro is herein reviewed, facilitating a detailed comparison on the role of seeded cells in vascular graft patency.

  15. Co-grafting of acrylamide and vinyl imidazole onto EB pre-irradiated silanized silica gel

    International Nuclear Information System (INIS)

    Silica-based adsorbent was prepared by radiation-induced grafting of acrylamide (AAM) and vinyl imidazole (VIM) onto the silanized silica. The silanized silica was pre-irradiated by electron beam and then reacted with AAM/VIM mixture solution under various conditions. FTIR, TG-DTA and XPS spectra manifested that AAM and VIM were successfully grafted onto the silica surface. The effects of monomer composition, absorbed dose, reaction time and reaction temperature on the grafting yield were investigated to optimize the reaction conditions. The results showed that the optimal reaction conditions were as follows: AAM/VIM mole ratio 6:4 with a total concentration of 4 mol/L, absorbed dose 100 kGy, reaction temperature 60 oC and reaction time 18 h. The SS-g-AAM/VIM adsorbent is expected to be useful for the removal of heavy-metal-ions from wastewater. - Highlights: → AAM and VIM were co-grafted to silanized silica by EB pre-irradiation grafting. → The grafted chain was characterized by thermo-analysis, FTIR and XPS. → Physical adsorption of monomer to silica plays an important role in radiation grafting.

  16. Posterior repair with perforated porcine dermal graft

    Directory of Open Access Journals (Sweden)

    G. Bernard Taylor

    2008-02-01

    Full Text Available OBJECTIVE: To compare postoperative vaginal incision separation and healing in patients undergoing posterior repair with perforated porcine dermal grafts with those that received grafts without perforations. Secondarily, the tensile properties of the perforated and non-perforated grafts were measured and compared. MATERIALS AND METHODS: This was a non-randomized retrospective cohort analysis of women with stage II or greater rectoceles who underwent posterior repair with perforated and non-perforated porcine dermal grafts (PelvicolTM CR Bard Covington, GA USA. The incidence of postoperative vaginal incision separation (dehiscence was compared. A secondary analysis to assess graft tensile strength, suture pull out strength, and flexibility after perforation was performed using standard test method TM 0133 and ASTM bending and resistance protocols. RESULTS: Seventeen percent of patients (21/127 who received grafts without perforations developed vaginal incision dehiscence compared to 7% (5/71 of patients who received perforated grafts (p = 0.078. Four patients with vaginal incision dehiscence with non-perforated grafts required surgical revision to facilitate healing. Neither tensile strength or suture pull out strength were significantly different between perforated and non-perforated grafts (p = 0.81, p = 0.29, respectively. There was no difference in the flexibility of the two grafts (p = 0.20. CONCLUSION: Perforated porcine dermal grafts retain their tensile properties and are associated with fewer vaginal incision dehiscences.

  17. Evaluation of the graft flow reserve after coronary artery bypass grafting by stress {sup 201}Tl myocardial SPECT. Comparison between arterial grafts and venous grafts

    Energy Technology Data Exchange (ETDEWEB)

    Ichikawa, Akihiro; Taki, Junichi; Nakajima, Kenichi; Kawasuji, Michio; Tonami, Norihisa [Kanazawa Univ. (Japan). School of Medicine

    1997-01-01

    We performed stress {sup 201}Tl myocardial SPECT to evaluate ischemia and perfusion reserve after coronary artery bypass grafting (CABG). A total of 103 patients was performed stress {sup 201}Tl myocardial SPECT one month after CABG. Each patient`s myocardium was divided into 9 segments and visually evaluated using five grade scoring system (0=defect, 1=severe decrease, 2=moderate decrease, 3=mild decrease, 4=normal uptake). Eleven of 133 (8.27%) segments covered by patent venous grafts showed reversible {sup 201}Tl defect, however, 36 of 117 (30.8%) segments which covered by patent arterial grafts showed reversible {sup 201}Tl defect. This finding was observed more significantly in arterial grafts than in venous grafts (p<0.001). These finding suggests that arterial grafts have lower flow capacity than venous grafts at peak exercise. (author)

  18. Evaluation of the graft flow reserve after coronary artery bypass grafting by stress 201Tl myocardial SPECT. Comparison between arterial grafts and venous grafts

    International Nuclear Information System (INIS)

    We performed stress 201Tl myocardial SPECT to evaluate ischemia and perfusion reserve after coronary artery bypass grafting (CABG). A total of 103 patients was performed stress 201Tl myocardial SPECT one month after CABG. Each patient's myocardium was divided into 9 segments and visually evaluated using five grade scoring system (0=defect, 1=severe decrease, 2=moderate decrease, 3=mild decrease, 4=normal uptake). Eleven of 133 (8.27%) segments covered by patent venous grafts showed reversible 201Tl defect, however, 36 of 117 (30.8%) segments which covered by patent arterial grafts showed reversible 201Tl defect. This finding was observed more significantly in arterial grafts than in venous grafts (p<0.001). These finding suggests that arterial grafts have lower flow capacity than venous grafts at peak exercise. (author)

  19. Starch Modification by Graft Copolymerization of Acrylonitrile

    Institute of Scientific and Technical Information of China (English)

    刘瑞贤; 李莉; 茹宗玲; 张黎明; 高建平; 田汝川

    2003-01-01

    The graft copolymerization of acrylonitrile (AN) onto starch under the initiation of potassium permanganate was investigated. The effect of various reaction conditions on the graft copolymerization was studied. The relationships between the grafting rate and the initiator concentration of potassium permanganate, monomer acrylonitrile and backbone starch, as well as reaction temperature were established. The oxidation reaction of starch with manganic ions and valence changes of manganic ions during the graft copolymerization were discussed. The results show that manganic ion Mn7+ underwent a series of valence changes during the graft copolymerization: Mn(Ⅶ) → Mn(Ⅳ) → Mn(Ⅲ) → Mn(Ⅱ). The grafting rate of the graft copolymerization of acrylonitrile onto starch is also given.

  20. Hydrophilic Silicone Resins Obtained by Radiation Grafting

    International Nuclear Information System (INIS)

    N-vinylpyrrolidone was grafted radiochemically on a silicone resin by pre-irradiation in the presence of oxygen. Under these conditions, peroxide groups capable of initiating radical copolymerization are formed. The trapped radicals do not seem to make any contribution. An RTV (Room Temperature Vulcanization) type silicone resin was used, i. e. a poly(dimethylsiloxane) crosslinked by vinyl-silane bonds. The unsaturated product was transparent. The silicones containing phenyl groups as well as saturated resins were also studied. Irradiation with 60Co gamma rays was performed in the 10-kCi irradiator of the Radiation Applications Group (GAR) at Saclay. Brief pre-irradiation tests with an electron accelerator were also performed. The amount of polyvinylpyrrolidone(PVP) grafted depends on the pre-irradiation dose and dose-rate as well as on the temperature and duration of the grafting proper. These different parameters were analysed. The grafting efficiency of PVP can be as much as 60%. The grafted copolymers are more or less opaque and coloured sections show that grafting remains peripheral. The transparency can be restored by immersion in water. The swelling in water is such that the ratio of absorbed water to grafted PVP varies between 0.8 and 1.5. When the grafting efficiency is higher than 50%, it is observed that the grafted PVP redissolves after swelling. The redissolving is due to the breaking of the grafted chains. For grafting rates below 30%, the grafted PVP silicones have notably high thermal stability. Examination of some properties of the grafted PVP silicones shows the additive nature of the properties of the grafted copolymers. Reference is made to the possible applications of these products, especially in biology and medicine. (author)

  1. Composite material

    Energy Technology Data Exchange (ETDEWEB)

    Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O' Neill, Hugh M. (Knoxville, TN)

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  2. Composite material

    Science.gov (United States)

    Hutchens, Stacy A.; Woodward, Jonathan; Evans, Barbara R.; O'Neill, Hugh M.

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  3. Biocelulose grafts: the future in artificial vascular grafts? preliminar results

    OpenAIRE

    Silva, Ivone; Loureiro, Luís; Araújo, Anabela; Alexandre F. Leitão; Faria, Miguel; Gama, F. M.

    2013-01-01

    Introduction: Vascular grafts, autogenous or artificial, are used to replace, bypass or maintain function of occluded, damaged, or diseased blood vessels of small, medium and large diameter. Vascular prostheses may be manufactured from synthetic, biological or biosynthetic materials. To our knowledge this is the first study to look at the hemocompatibility of bacterial cellulose membrane reinforced by the presence of polyvinyl alcohol. Materials/ methods The first aim of ...

  4. Separation of Tc-99m By Means of Radiation Grafted Membranes

    International Nuclear Information System (INIS)

    Characterization and possibility of practical use of different polymeric materials for the purpose of radioactive isotopes separation from their wastes were studied. The influence of chemical treatment on the chelation or adsorption capacity at 25 degree was studied. The equilibrium swelling of these polymers in distilled water at room temperature and the effect of solvent composition on the graft yield were also investigated. In this study, the mechanical, chemical resistance and other properties for the grafted, untreated and treated membranes we reinvestigated. The performance of the membranes was studied as a function of time and degree of grafting. The effect of chemical treatment on the initial activity and separation of Tc-99m have been studied. It has been noticed that the base polymer and degree of grafting have greet influence on the Tc uptake

  5. Grafting of PEG400 onto the surface of LLDPE/SMA film

    Institute of Scientific and Technical Information of China (English)

    CHEN Gufeng; ZHANG Yi; ZHU Yafei; XU Jiarui

    2007-01-01

    Linear low-density polyethylene (LLDPE)was melt and blended with styrene-maleic anhydride copolymer (SMA).The blending films were then immersed in poly(ethylene glycol)400 (PEG400) at room temperature.The surface composition of the blend films was determined by Fourier transform infra-red spectroscopy coupled with a variable incidence angle attenuated total reflection accessory (ATR-FTIR).Results show that PEG400 can be grafted onto the surface of the films via esterification with SMA.The immersion of PEG promotes the enrichment of SMA onto the surface of the films.The water contact angle data show that grafting of PEG400 onto PE can greatly improve the hydrophilicity of the PE surface.These experiments show that surface functionalization of polyethylene films by blending SMA and then surface grafting of PEG is feasible,which suggest an effective and simple route for PE surface modification via blending and grafting.

  6. Radiation sterilization of tissue grafts

    International Nuclear Information System (INIS)

    The Tissue Bank at the Tata Memorial Hospital was started in 1989 in collaboration with the Department of Atomic Energy, Government of India, as part of an IAEA project to promote the use of nuclear technology for peaceful purposes. The Bank produces freeze dried, gamma irradiated allografts such as skin, amniotic membrane, dura mater, fascia lata, bone blocks/chips/dust, iliac crest, femoral heads and ribs. Tissues are harvested from cadavers or obtained secondary to surgical procedures. After processing, the grafts are exposed to 25 kGy of gamma radiation. The grafts have found use in a variety of clinical conditions like burns, non-union fractures, periodontal osseous defects and surgical reconstructions. (author)

  7. Surface modification of polydimethylsiloxane with photo-grafted poly(ethylene glycol) for micropatterned protein adsorption and cell adhesion.

    Science.gov (United States)

    Sugiura, Shinji; Edahiro, Jun-ichi; Sumaru, Kimio; Kanamori, Toshiyuki

    2008-06-01

    In this study, we applied photo-induced graft polymerization to micropatterned surface modification of polydimethylsiloxane (PDMS) with poly(ethylene glycol). Two types of monomers, polyethylene glycol monoacrylate (PEGMA) and polyethylene glycol diacrylate (PEGDA), were tested for surface modification of PDMS. Changes in the surface hydrophilicity and surface element composition were characterized by contact angle measurement and electron spectroscopy for chemical analysis. The PEGMA-grafted PDMS surfaces gradually lost their hydrophilicity within two weeks. In contrast, the PEGDA-grafted PDMS surface maintained stable hydrophilic characteristics for more than two months. Micropatterned protein adsorption and micropatterned cell adhesion were successfully demonstrated using PEGDA-micropatterned PDMS surfaces, which were prepared by photo-induced graft polymerization using photomasks. The PEGDA-grafted PDMS exhibited useful characteristics for microfluidic devices (e.g. hydrophilicity, low protein adsorption, and low cell attachment). The technique presented in this study will be useful for surface modification of various research tools and devices. PMID:18242961

  8. Photoelectrochemical performance of CdS nanorods grafted vertically aligned TiO{sub 2} nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ya; Jiang, Jiangang [International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering (MFPE), Xi’an Jiaotong University (XJTU), No. 28 West Xianning Road, Xi’an 710049 (China); Xu, Quan [Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Li, Mingtao, E-mail: mingtao@mail.xjtu.edu.cn [International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering (MFPE), Xi’an Jiaotong University (XJTU), No. 28 West Xianning Road, Xi’an 710049 (China); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Guo, Liejin [International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering (MFPE), Xi’an Jiaotong University (XJTU), No. 28 West Xianning Road, Xi’an 710049 (China)

    2013-11-15

    Graphical abstract: - Highlights: • TiO{sub 2} nanorods/CdS nanorods composite samples were successfully achieved. • The photocurrent density increased by 100 percent compared with pure TiO{sub 2}. • Photocurrent density increase mechanism of this photoanode was also forecasted. - Abstract: In this study, TiO{sub 2} nanorods/CdS nanorods composite samples were successfully synthesized by grafting CdS nanorods on vertically aligned TiO{sub 2} nanorods. A two-step hydrothermal method was used to prepare the samples. Some properties of the samples, such as morphological, structural, and optical properties were characterized by energy-dispersive X-ray detection, field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and ultraviolet-visible spectroscopy. Moreover, photoelectrochemical properties were studied via current-voltage and photocurrent spectrum measurements. The results showed that CdS nanorods grafted on top of TiO{sub 2} nanorods like a lawn. The amount grafted as well as the diameter and crystallinity of CdS nanorods increased first and then decreased as the grafting time increased, due to Ostwald ripening. Under the back-side illumination, the composite film with 2 h grafting time exhibited the highest photocurrent density which was almost twice of that of the pure TiO{sub 2} nanorods.

  9. Evaluation of early coronary graft patency after coronary artery bypass graft surgery using multislice computed tomography angiography

    Directory of Open Access Journals (Sweden)

    Raissi Kamal

    2009-12-01

    Full Text Available Abstract Background Coronary artery bypass graft (CABG surgery is the standard of care in the treatment of advanced coronary artery disease, and its long-term results are affected by the failure of bypass grafts. The aim of the present study was to evaluate the early patency rate in coronary bypass grafts. Methods A total of 107 consecutive patients who underwent CABG were included in this study. Early graft patency was evaluated via computed tomography (CT angiography in the first week after surgery. Results There were a total of 366 grafts, comprised of 250 venous grafts and 116 arterial grafts. Multi-slice CT detected acute graft occlusions in 32 (8.7% of all the grafts, including 26 (10% of the 250 venous grafts and 6 (5% of the 116 arterial grafts. The patency rates obtained were 97.3% for the left internal mammary (IMA grafts, 50% for the radial artery grafts, and 50% for the right IMA grafts. Additionally, 107 (96.4% grafts to the left anterior descending artery (LAD were classified as patent, whereas 1 (30% of the 3 grafts in the left circumflex (LCX region and 1 (50% of the 2 grafts in the right coronary artery (RCA territory were found to be occluded. In the venous category, 8 (13.7% of the 58 grafts to LAD were found to be occluded. In the LCX region, 9 (8.5% of the 106 grafts were classified as occluded, while the remaining 97 (91.5% grafts were patent. The venous grafts to RCA were occluded in 9 (10.4% of the 86 grafts. Amongst the multiple preoperative, intraoperative, and postoperative factors, pump time was significantly longer in the patients with occluded grafts than in those with patent grafts (P = 0.04. Conclusion The IMA grafts had the highest early patency rate amongst the coronary bypass grafts. However, the other arterial grafts were associated with a high rate of acute occlusions.

  10. Grafting rays fellow travel Teichmuller geodesics

    CERN Document Server

    Choi, Young-Eun; Rafi, Kasra

    2010-01-01

    Given a measured geodesic lamination on a hyperbolic surface, grafting the surface along multiples of the lamination defines a path in Teichmuller space, called the grafting ray. We show that every grafting ray, after reparametrization, is a Teichmuller quasi-geodesic and stays in a bounded neighborhood of a Teichmuller geodesic. As part of our approach, we show that grafting rays have controlled dependence on the starting point. That is, for any measured geodesic lamination Lambda, the map of Teichmuller space which is defined by grafting along Lambda is L-Lipschitz with respect to the Teichmuller metric, where L is a universal constant. This Lipschitz property follows from an extension of grafting to an open neighborhood of Teichmuller space in the space of quasi-Fuchsian groups.

  11. Fixation of tibial plateau fractures with synthetic bone graft versus natural bone graft: a comparison study.

    LENUS (Irish Health Repository)

    Ong, J C Y

    2012-06-01

    The goal of this study was to determine differences in fracture stability and functional outcome between synthetic bone graft and natural bone graft with internal fixation of tibia plateau metaphyseal defects.

  12. Separation of maleic anhydride grafted polypropylene using multidimensional high-temperature liquid chromatography.

    Science.gov (United States)

    Prabhu, K N; Macko, T; Brüll, R; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2016-04-01

    Functionalization addresses a property gap of polyolefins and opens new perspectives due to improved surface properties in applications like composites (e.g., glass fiber reinforced polypropylene) and anti-corrosive coatings for metals. Various techniques have been developed to characterize functionalized polyolefins, yet no analytical approach addressing their chemical heterogeneity exists. Using High Temperature Size Exclusion Chromatography (HT-SEC) coupled to infrared spectroscopy we could show for two model samples of polypropylene grafted maleic anhydride (PP-g-MA), differing in their nominal MA content, that the grafting density increases with decreasing molar mass. Crystallization Analysis Fractionation (CRYSTAF) does not enable to separate these samples according to their composition to the extent required. Yet, when using High Temperature High Performance Liquid Chromatography (HT-HPLC), with either silica gel or Mica as stationary phase and a gradient mobile phase, a deformulation into a grafted and a non-grafted fraction could be achieved. This was confirmed by analyzing the eluted fractions by infrared spectroscopy. Hyphenating the separation according to composition with a separation according to molar mass (HT-HPLC x HT-SEC) enabled for the first time to reveal the bivariate distribution of PP-g-MA with regard to the molar mass and composition. Using on-line infrared detection quantitative information on the compositional and molar mass parameters of the individual fractions could be obtained. PMID:26961914

  13. Novel expansion techniques for skin grafts

    Science.gov (United States)

    Kadam, Dinesh

    2016-01-01

    The quest for skin expansion is not restricted to cover a large area alone, but to produce acceptable uniform surfaces, robust engraftment to withstand mechanical shear and infection, with a minimal donor morbidity. Ease of the technique, shorter healing period and reproducible results are essential parameters to adopt novel techniques. Significant advances seen in four fronts of autologous grafting are: (1) Dermal–epidermal graft expansion techniques, (2) epidermal graft harvests technique, (3) melanocyte-rich basal cell therapy for vitiligo and (4) robust and faster autologous cell cultures. Meek's original concept that the sum of perimeter of smaller grafts is larger than the harvested graft, and smaller the graft size, the greater is the potential for regeneration is witnessed in newer modification. Further, as graft size becomes smaller or minced, these micrografts can survive on the wound bed exudate irrespective of their dermal orientation. Expansion produced by 4 mm × 4 mm sized Meek micrografts is 10-folds, similarly 0.8 mm × 0.8 mm size micrografts produce 100-fold expansion, which becomes 700-fold with pixel grafts of 0.3 mm × 0.3 mm size. Fractional skin harvest is another new technique with 700 μ size full thickness graft. These provide instant autologous non-cultured graft to cover extensive areas with similar quality of engraftment surface as split skin grafts. Newer tools for epidermal blister graft harvest quickly, with uniform size to produce 7-fold expansions with reproducible results. In addition, donor area heals faster with minimal scar. Melanocyte-rich cell suspension is utilised in vitiligo surgery tapping the potential of hair root melanocytes. Further advances in the cell culture to reduce the cultivation time and provide stronger epidermal sheets with dermal carrier are seen in trials. PMID:27274117

  14. Outcomes of AV Fistulas and AV Grafts after Interventional Stent-Graft Deployment in Haemodialysis Patients

    International Nuclear Information System (INIS)

    PurposeThe study was designed to assess outcomes of arteriovenous (AV) accesses after interventional stent-graft deployment in haemodialysis patients.Materials and Methods63 haemodialysis patients with 66 AV fistulas and AV grafts were treated by interventional stent-graft deployment from 2006 to 2012 at our hospital. Data of these patients were retrospectively analysed for location of deployed stent-grafts, occurrence and location of (re-)stenosis and (re-)thrombosis. Complex stenosis was the most frequent indication for stent-graft deployment (45.5 %), followed by complications of angioplasty with vessel rupture or dissection (31.8 %).ResultsA high rate of procedural success was achieved (98.5 %). The most frequent location of the deployed stent-graft was the draining vein (66.7 %). Stent-graft deployment was more frequent in AV grafts than in AV fistulas. Primary patency was 45.5 % at 6 month, 31.3 % at 12 month and 19.2 % at 24 month. Primary patency was significantly better for AV fistulas than for AV grafts with deployed stent-grafts. Patency of the deployed stent-graft was much better than overall AV access primary patency with deployed stent-graft. Re-stenosis with thrombosis was the most frequent indication for re-intervention. Most frequent location of re-stenosis was the draining vein (37.1 %), followed by stenosis at the AV access (29.5 %) and the deployed stent-graft (23.5 %).ConclusionRe-stenosis and re-thrombosis remain frequent in AV fistulas and AV grafts in haemodialysis patients despite stent-graft deployment. Re-stenosis of the deployed stent-graft is, only in the minority of the cases, responsible for AV access dysfunction

  15. Outcomes of AV Fistulas and AV Grafts after Interventional Stent-Graft Deployment in Haemodialysis Patients

    Energy Technology Data Exchange (ETDEWEB)

    Schmelter, Christopher, E-mail: christopher.schmelter@klinikum-ingolstadt.de; Raab, Udo, E-mail: udo.raab@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Diagnostic and Interventional Radiology (Germany); Lazarus, Friedrich, E-mail: friedrich.lazarus@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Nephrology (Germany); Ruppert, Volker, E-mail: volker.ruppert@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Vascular Surgery (Germany); Vorwerk, Dierk, E-mail: dierk.vorwerk@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Diagnostic and Interventional Radiology (Germany)

    2015-08-15

    PurposeThe study was designed to assess outcomes of arteriovenous (AV) accesses after interventional stent-graft deployment in haemodialysis patients.Materials and Methods63 haemodialysis patients with 66 AV fistulas and AV grafts were treated by interventional stent-graft deployment from 2006 to 2012 at our hospital. Data of these patients were retrospectively analysed for location of deployed stent-grafts, occurrence and location of (re-)stenosis and (re-)thrombosis. Complex stenosis was the most frequent indication for stent-graft deployment (45.5 %), followed by complications of angioplasty with vessel rupture or dissection (31.8 %).ResultsA high rate of procedural success was achieved (98.5 %). The most frequent location of the deployed stent-graft was the draining vein (66.7 %). Stent-graft deployment was more frequent in AV grafts than in AV fistulas. Primary patency was 45.5 % at 6 month, 31.3 % at 12 month and 19.2 % at 24 month. Primary patency was significantly better for AV fistulas than for AV grafts with deployed stent-grafts. Patency of the deployed stent-graft was much better than overall AV access primary patency with deployed stent-graft. Re-stenosis with thrombosis was the most frequent indication for re-intervention. Most frequent location of re-stenosis was the draining vein (37.1 %), followed by stenosis at the AV access (29.5 %) and the deployed stent-graft (23.5 %).ConclusionRe-stenosis and re-thrombosis remain frequent in AV fistulas and AV grafts in haemodialysis patients despite stent-graft deployment. Re-stenosis of the deployed stent-graft is, only in the minority of the cases, responsible for AV access dysfunction.

  16. The autologus graft of epithelial tissue culture

    Directory of Open Access Journals (Sweden)

    Minaee B

    1999-08-01

    Full Text Available With the intention of research about culture and autologus graft of epithelial tissue we used 4 french Albino Rabbits with an average age of 2 months. After reproduction on the support in EMEM (Eagle's Minimum Essential Medium we used this for graft after 4 weeks. This region which grafted total replaced. After fixation of this sample and passing them through various process, histological sections were prepared. These sections were stained with H & E and masson's trichrome and studied by light microscope. We succeeded in graft. We hope in the near future by using the method of epithelium tissue culture improving to treat burned patients.

  17. Highly hydrophilic ultra-high molecular weight polyethylene powder and film prepared by radiation grafting of acrylic acid

    Science.gov (United States)

    Wang, Honglong.; Xu, Lu.; Li, Rong.; Pang, Lijuan.; Hu, Jiangtao.; Wang, Mouhua.; Wu, Guozhong.

    2016-09-01

    The surface properties of ultra-high molecular weight polyethylene (UHMWPE) are very important for its use in engineering or composites. In this work, hydrophilic UHMWPE powder and film were prepared by γ-ray pre-irradiation grafting of acrylic acid (AA) and further neutralization with sodium hydroxide solution. Variations in the chemical structure, grafting yield and hydrophilicity were investigated and compared. FT-IR and XPS analysis results showed that AA was successfully grafted onto UHMWPE powder and film; the powder was more suitable for the grafting reaction in 1 wt% AA solution than the film. Given a dose of 300 kGy, the grafting yield of AA was ∼5.7% for the powder but ∼0.8% for the film under identical conditions. Radiation grafting of a small amount of AA significantly improved the hydrophilicity of UHMWPE. The water contact angle of the UHMWPE-g-PAA powder with a grafting yield of AA at ∼5.7% decreased from 110.2° to 68.2°. Moreover, the grafting powder (UHMWPE-g-PAA) exhibited good dispersion ability in water.

  18. Radiation-induced and RAFT-mediated grafting of poly(hydroxyethyl methacrylate) (PHEMA) from cellulose surfaces

    International Nuclear Information System (INIS)

    This paper presents the results of RAFT mediated free-radical graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto cellulose fibers in a “grafting-from” approach under γ-irradiation. The effects of absorbed dose and monomer concentration on the graft ratios were investigated at different monomer (HEMA) to RAFT agent (cumyl dithiobenzoate, CDB) ratios. Cellulose-g-PHEMA copolymers with various graft ratios up to 92% (w/w) have been synthesized. The synthesized copolymers were characterized by ATR-FTIR spectroscopy, X-ray photoelectron spectroscopy, elemental analysis and scanning electron microscopy. The results of various techniques confirmed the existence of PHEMA in the copolymer composition. - Highlights: • Poly(hydroxyethylmethacrylate) was grafted from cellulose surface w/w a RAFT agent by gamma irradiation. • Control of molecular weight and distribution of grafted chains were achieved in RAFT-mediated grafting reactions. • Graft copolymers were characterized by FTIR-ATR, XPS, SEM, elemental analysis and contact angle measurements

  19. Radiation induced graft copolymerization of cellulosic fabric waste and its application in the removal of cyanide and dichromate from aqueous solution

    International Nuclear Information System (INIS)

    Graft polymerization and crosslinking in radiation processing are attractive techniques for modification of the chemical and physical properties of the conventional polymers. The graft polymerization and subsequent chemical treatment can introduce a chelate agent function into a conventional polymer such as cellulosic fabric. Cellulosic graft copolymers were prepared by the reaction of the fiber with acrylonitrile (AN) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) in DMF initiated by gamma-radiation 60Co. The grafted fabric was chemically treated with hydroxyl amine to obtain amidoxime form. Factors affecting on the grafting such as radiation dose, monomer concentration and solvent concentration as well as monomer composition was investigated. The chemically modified graft fabric was applied for recovery of cyanide and dichromate from aqueous solution. The CN show removal percent 89%, whereas dichromate has 65% removal percent

  20. Radiation Graft Copolymerization of Butyl methacrylate and Acrylamide onto Low density polyethylene and polypropylene films and its application in wastewater treatment

    International Nuclear Information System (INIS)

    Butyl methacrylate and Acrylamide (BMA/AAm) comonomer were grafted onto Low density polyethylene and polypropylene films using direct gamma radiation by grafting technique. The influences of grafting conditions such as solvent, monomer concentration, monomer composition, and irradiation dose on the grafting yield were determined. It was found that, using DMF as a solvent enhanced the copolymerization process. The grafting yield increases with comonomer concentration up to 60 %. . Also it was found that, the degree of grafting of (BMA/AAm) onto LDPE and PP films increases as the AAm content increases till optimum value at (50:50) %. The grafting yield of the comonomer found to be increased with increasing radiation dose. It was observed that the degree of grafting of polyethylene films is higher than that for polypropylene films. Some selected properties of the graft copolymers, such as water uptake and thermal properties determined by using thermogravimetric analysis (TGA) has been carried out. The morphology and structure of grafted films was investigated by using SEM, IR and X-ray diffraction. The improvement in such properties of the prepared copolymers was observed which makes possible uses in some practical applications such as in the removal of some heavy metals from wastewater. It was found that the maximum metal uptake by the copolymer is ordered in the sequence of Cu2+ > CO2+ > Ni2+ ions.

  1. Radiation graft copolymerization of butyl methacrylate and acrylamide onto low density polyethylene and polypropylene films, and its application in wastewater treatment

    Science.gov (United States)

    Abdel Ghaffar, A. M.; El-Arnaouty, M. B.; Aboulfotouh, Maysara E.; Taher, N. H.; Taha, Ahmed A.

    2014-09-01

    Butyl methacrylate and acrylamide (BMA/AAm) comonomers were grafted onto low-density polyethylene (LDPE) and polypropylene (PP) films using the mutual gamma radiation grafting technique. The influences of grafting conditions such as solvent, monomer concentration, monomer composition, and irradiation dose on the grafting yield were determined. It was found that using dimethyl formamide as a solvent enhanced the copolymerization process. The grafting yield increases as the comonomer concentration increases up to 60%. Also it was found that the degree of grafting of BMA/AAm onto both LDPE and PP films increases as the AAm content increases till an optimum value at 50:50 wt%. The grafting yield of the comonomers was found to increase with increase in the radiation dose. It was observed that the degree of grafting of polyethylene films is higher than that of polypropylene (PP) films at the same conditions. Some selected properties of the graft copolymers, such as water uptake and thermal properties, were determined using thermogravimetric analysis. The morphology and structure of the grafted films were investigated using scanning electron microscopy, infra-red, and X-ray diffraction. Improvement in such properties of the prepared copolymers was observed which offers possible uses in some practical applications such as the removal of some heavy metals from wastewater. It was found that the maximum metal uptake by the copolymer followed the order Cu2+>Co2+>Ni2+ ions.

  2. Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix.

    Science.gov (United States)

    Nair, Nitish; Wentzel, Nathaniel; Jayaraman, Arthi

    2011-05-21

    In efforts to produce polymeric materials with tailored physical properties, significant interest has grown around the ability to control the spatial organization of nanoparticles in polymer nanocomposites. One way to achieve controlled particle arrangement is by grafting the nanoparticle surface with polymers that are compatible with the matrix, thus manipulating the interfacial interactions between the nanoparticles and the polymer matrix. Previous work has shown that the molecular weight of the grafted polymer, both at high grafting density and low grafting density, plays a key role in dictating the effective inter-particle interactions in a polymer matrix. At high grafting density nanoparticles disperse (aggregate) if the graft molecular weight is higher (lower) than the matrix molecular weight. At low grafting density the longer grafts can better shield the nanoparticle surface from direct particle-particle contacts than the shorter grafts and lead to the dispersion of the grafted particles in the matrix. Despite the importance of graft molecular weight, and evidence of non-trivial effects of polydispersity of chains grafted on flat surfaces, most theoretical work on polymer grafted nanoparticles has only focused on monodisperse grafted chains. In this paper, we focus on how bidispersity in grafted chain lengths affects the grafted chain conformations and inter-particle interactions in an implicit solvent and in a dense homopolymer polymer matrix. We first present the effects of bidispersity on grafted chain conformations in a single polymer grafted particle using purely Monte Carlo (MC) simulations. This is followed by calculations of the potential of mean force (PMF) between two grafted particles in a polymer matrix using a self-consistent Polymer Reference Interaction Site Model theory-Monte Carlo simulation approach. Monte Carlo simulations of a single polymer grafted particle in an implicit solvent show that in the bidisperse polymer grafted particles

  3. The Healing Effects of Autologous Mucosal Grafts in Experimentally Injured Rabbit Maxillary Sinuses

    Science.gov (United States)

    Topdag, Murat; Kara, Ahmet; Konuk, Esma; Demir, Necdet; Ozturk, Murat; Calıskan, Sebla; Topdag, Deniz Ozlem; Ulubil, Arif; Keskin, Ibrahim Gurkan; Iseri, Mete

    2016-01-01

    Objectives Healing processes of the nose and paranasal sinuses are quite complex, and poorly understood. In this study, we aimed to compare the effect of mucosal autologous grafts on the degenerated rabbit maxillary sinus mucosa with spontaneous wound healing. It is hypothesized that mucosal grafts will enhance ciliogenesis and improve the morphology of regenerated cilia. Methods Ten female New Zealand rabbits were included in the study. They underwent external maxillary sinus surgery through a transcutaneous approach. A total of 20 maxillary sinuses were randomly divided into 2 groups: ‘spontaneous healing group’ and ‘autologous graft group.’ The animals were sacrificed at the 14th day after the surgery. Scanning electron microscope (SEM), and light microscope were used for the evaluation. Results Cellular composition of the graft group is better than the spontaneous healing group. The graft group had larger areas covered with ciliary epithelium than the spontaneous healing group, and the mean length of the cilias were also longer. Additionally, there were wider cilia with abnormal morphology areas in the spontaneous healing group. Conclusion In our opinion, covering of the denuded areas with a graft improves re-epithelization, and may prevent the early complications after sinus surgeries. PMID:26976026

  4. Modificação de fibra de carbono com PBLH e sua utilização em compósitos com resina epoxídica Hydroxyl-terminated polybutadiene-grafted carbon fiber in epoxy resin-based composites

    Directory of Open Access Journals (Sweden)

    Fábio L. Barcia

    1999-06-01

    Full Text Available Fibras de carbono contendo 1,4 e 2,1mmol/g de grupos carboxila e hidroxila fenólica, respectivamente, foram modificadas através de reação com TDI, resultando em fibras contendo 3,1 mmol/g de grupos isocianato. A introdução de grupos isocianato na superfície da fibra tornou possível a sua modificação com polibutadieno líquido hidroxilado. Fibras de carbono modificadas e não modificadas foram empregadas na preparação de compósitos com resina epoxídica, sendo observado um aumento considerável de resistência ao impacto em compósitos constituídos de fibras de carbono enxertadas com PBLH, devido, provavelmente, à natureza elastomérica da interface e à melhor adesão interfacial.Carbon fibers containing 1,4 e 2,1 mmol/g of carboxyl and phenolic hydroxyl groups, respectively, were modified through the reaction with TDI. The presence of isocyanate groups at the fiber surface made possible the fiber modification with hydroxyl terminated polybutadiene (HTPB. These modified and unmodified carbon fibers were employed in the preparation of epoxy resin-based composites. A substantial improvement in the impact properties was observed in the composites with HTPB-grafted carbon fibers when compared to unmodified carbon fibers. These results may be attributed to a higher interfacial adhesion promoted by reactions between the functional groups present at the modified carbon fiber surface and the epoxy matrix.

  5. Graft-versus-host disease versus graft-versus-leukemia.

    Science.gov (United States)

    Negrin, Robert S

    2015-01-01

    Graft-versus-host disease (GVHD) is a significant clinical problem after allogenic hematopoietic cell transplantation (HCT) associated with substantial morbidity and mortality that limits the potential utility of transplantation. Associated with GVHD is the well-recognized phenomenon of the graft-versus-leukemia (GVL) effect that results in reduced risk of disease relapse. GVL effects have been observed after treatment for a broad range of hematological malignancies. Both GVHD and GVL are the results of T cell-effector functions that frames a major question in the field of how linked are these two phenomena. A major goal of basic science and translational research has been to develop strategies to reduce the risk of GVHD while maintaining or enhancing GVL. In this review, a number of different strategies developed from preclinical animal models will be explored with a focus on those approaches that have been extended to the clinic in an attempt to achieve this goal. Needless to say, there is no proven strategy; however, with the use of modern technology and clinical translation, there has been substantial progress toward this goal of reducing the risks of GVHD while promoting and enhancing GVL responses. PMID:26637726

  6. Design and development of multilayer vascular graft

    Science.gov (United States)

    Madhavan, Krishna

    2011-07-01

    Vascular graft is a widely-used medical device for the treatment of vascular diseases such as atherosclerosis and aneurysm as well as for the use of vascular access and pediatric shunt, which are major causes of mortality and morbidity in this world. Dysfunction of vascular grafts often occurs, particularly for grafts with diameter less than 6mm, and is associated with the design of graft materials. Mechanical strength, compliance, permeability, endothelialization and availability are issues of most concern for vascular graft materials. To address these issues, we have designed a biodegradable, compliant graft made of hybrid multilayer by combining an intimal equivalent, electrospun heparin-impregnated poly-epsilon-caprolactone nanofibers, with a medial equivalent, a crosslinked collagen-chitosan-based gel scaffold. The intimal equivalent is designed to build mechanical strength and stability suitable for in vivo grafting and to prevent thrombosis. The medial equivalent is designed to serve as a scaffold for the activity of the smooth muscle cells important for vascular healing and regeneration. Our results have shown that genipin is a biocompatible crosslinker to enhance the mechanical properties of collagen-chitosan based scaffolds, and the degradation time and the activity of smooth muscle cells in the scaffold can be modulated by the crosslinking degree. For vascular grafting and regeneration in vivo, an important design parameter of the hybrid multilayer is the interface adhesion between the intimal and medial equivalents. With diametrically opposite affinities to water, delamination of the two layers occurs. Physical or chemical modification techniques were thus used to enhance the adhesion. Microscopic examination and graft-relevant functional characterizations have been performed to evaluate these techniques. Results from characterization of microstructure and functional properties, including burst strength, compliance, water permeability and suture

  7. Improvement of polymer stability by radiation grafting

    International Nuclear Information System (INIS)

    Losses of the stabilizer due to extractability or volatility immediately affect ultimate performance of polymer product. A new approach to increase the persistence of the stabilizer in the final product is to chemically bind it to the polymer backbone. Radiation grafting or crosslinking could be an efficient method for this, when the stabilizer is polymerizable. By a mutual gamma irradiation method, photoprotector 2-hydroxy-4-(3-methacryloxy-2- hydroxy-propoxy) benzophenone (HMB) has been readily grafted to low density polyethylene (LDPE) in benzene, tetrahydrofuran and methanol solution, respectively. Surface grafting occurs in a methanol solution of stabilizer, while in benzene and tetrahydrofuran solutions of stabilizer, grafting proceeds more or less in the inner parts of the polymeric film as well. The grafted LDPE film in methanol and tetrahydrofuran (containing 1 w/w % of grafted HMB), 1 w/w % blended HMB with LDPE and nongrafted LDPE film, were all exposed to accelerated aging and natural weathering and their spectral changes, expressed by the carbonyl index, were then compared. The change of elongation at break and tensile strength were measured in the course of aging. UV stability tests on aged films and change in mechanical properties indicate a pronounced protective effect achieved by grafted stabilizer. Grafting in methanol solution appears to be an efficient photostabilization treatment and the most economical with respect to the consumption of monomer, the grafting yield being less than 0.5%. Surface grafting is an efficient photostabilization method since grafted stabilizer is chemically bound to a polymeric surface and in this way the problem of evaporation of blended stabilizers during the prolonged use of polymeric materials is eliminated. (author)

  8. Caraterização composicional do AES - um copolímero de enxertia de poli(estireno-co-acrilonitrila em poli(etileno-co-propileno-co-dieno Compositional characterization of AES a graft copolymer based on poly(styrene-co-acrylonitrile and poly(etyhlene-co-propylene-co-diene

    Directory of Open Access Journals (Sweden)

    Renato Turchet

    2006-06-01

    Full Text Available O objetivo deste trabalho é a caracterização do AES, um copolímero de enxertia de poli(estireno-co-acrilonitrila, SAN, em poli(etileno-co-propileno-co-dieno, EPDM. Para tanto, o AES foi submetido à extração seletiva de seus componentes: o SAN livre, o EDPM livre, e o copolímero de enxertia EPDM-g-SAN. O AES e suas frações foram caracterizados por espectroscopia de infravermelho, análise elementar, calorimetria diferencial de varredura e ressonância magnética nuclear, RMN¹H e RMN13C. O AES analisado apresenta a seguinte composição em massa: 65% de EPDM-g-SAN, 13% de EPDM livre e 22% de SAN livre. O EPDM apresenta 69,8% em massa de etileno, 26,5% em massa de propileno e 4,6% em massa do dieno, 2-etilideno-5-norboneno, ENB. O SAN apresenta razão em massa acrilonitrila/estireno de 28/72 e distribuição randômica de comonômeros de estireno e acrilonitrila. Estes resultados são concordantes com a composição do AES fornecida pelo fabricante, indicando que a metodologia proposta é adequada.This work aims the characterization of AES, a graft copolymer based on poly(styrene-co-acrylonitrile, SAN, and poly(etyhlene-co-propylene-co-diene, EPDM. AES was submitted to selective extraction of its components: free SAN, EPDM chains and the graft copolymer EPDM-g-SAN. AES and its fractions were characterized by infrared spectroscopy, elemental analysis, differential scanning calorimetry, 13C and ¹H nuclear magnetic resonance. The AES has 65 wt % of EPDM-g-SAN, 13 wt % of free EPDM and 22 wt % of free SAN. EPDM has 69.8 wt % of ethylene, 26.5 wt % of propylene and 4.6 wt % of diene, 2-ethylidene-5-norbonene ENB. SAN presents acrylonitrile/styrene mass ratio of 28/72 and a random distribution of acrylonitrile and styrene comonomers. These results are in agreement with the composition reported by the AES supplier, indicating that the proposed methodology is adequate.

  9. Biomimetic surface modification of polyurethane with phospholipids grafted carbon nanotubes.

    Science.gov (United States)

    Tan, Dongsheng; Liu, Liuxu; Li, Zhen; Fu, Qiang

    2015-08-01

    To improve blood compatibility of polyurethane (PU), phospholipids grafted carbon nanotubes (CNTs) were prepared through zwitterion-mediated cycloaddition reaction and amide condensation, and then were added to the PU as fillers via solution mixing to form biomimetic surface. The properties of phospholipids grafted CNTs (CNT-PC) were investigated by thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance ((1) H NMR). The results indicated that the phospholipids were grafted onto CNTs in high efficiency, and the hydrophilicity and dispersibility of the modified CNTs were improved effectively. The structures and properties of composites containing CNT-PC were investigated by optical microscope, XPS, and water contact angles. The results indicated that phospholipids were enriched on the surface with addition of 0.1 wt % of CNT-PC, which significantly reduced protein adsorption and platelet adhesion. The method of carrying phospholipids on the nanofiller to modify polymers has provided a promising way of constructing biomimetic phospholipid membrane on the surface to improve blood compatibility. PMID:25630300

  10. A review of 155 extra-anatomic bypass grafts.

    OpenAIRE

    Foster, M.C.; Mikulin, T; Hopkinson, B R; Makin, G. S.

    1986-01-01

    Extra-anatomic bypass grafting has been used as treatment for patients with aorto-iliac disease who were considered unfit for aortic surgery. Eighty five percent of the patients had ischaemic pain at rest or skin necrosis. One hundred and three femorofemoral (FF) grafts, 40 axillounifemoral and 12 axillobifemoral grafts were performed. Femoropopliteal extension grafts were performed in 39 cases. The three year cumulative graft patency rate was 69% for FF grafts and 48% for both types of axill...

  11. PREPARATION AND APPLICATION OF DIMER ACID/LIGNIN GRAFT COPOLYMER

    OpenAIRE

    Run Fang; Xiansu Cheng; Wu-shi Lin

    2011-01-01

    Dimer acid (DA) was grafted onto lignin (EHL) to form a graft copolymer DA-g-EHL. The selection of the reaction type and the optimization of the reaction conditions for the grafting reaction were conducted through orthogonal and single factor experiments. FT-IR and thermal analysis were used to characterize the graft product. It was found that, compared with free radical grafting, DA can be grafted onto EHL more effectively by ester condensation with strongly acidic cation exchange resin as a...

  12. Influence of ischemia before vein grafting on early hyperplasia of the graft and the dynamic changes of the intima after grafting

    Directory of Open Access Journals (Sweden)

    Zou RongJiang

    2012-09-01

    Full Text Available Abstract Background To investigate both the influence of ischemia before grafting on early hyperplasia of the vein grafts, and the dynamic changes of the intima after grafting in a rabbit model of vein graft disease. Methods We performed paired vein graft experiments under different ischemic conditions (15 vs. 60 min; 15 vs. 90 min in the neck of the rabbits and compared the differences between the grafts. Clopidogrel, an anti-platelet agent, was administered before and after surgery. Twenty-eight days after the grafting procedure, the veins were evaluated microscopically. The dynamic changes of the intima after grafting were evaluated by scanning electron microscopy over time. Results The vein grafts subjected to 60- or 90-min ischemia exhibited no differences compared to those subjected to 15-min ischemia in terms of the mean thickness of the intimal, medial, and adventitial layers of the graft. Similarly, there was no difference in the Ki-67 labeling index (proliferation marker between the vein grafts. Vein grafts with 15-min ischemia lost endothelial cells (ECs but healed by 3 days post graft, whereas vein grafts with 90-min ischemia suffered serious EC loss, which was restored with new ECs during days 2 to 14 post graft. Conclusions Ninety-minute ischemia before vein grafting can cause serious EC loss, but does not increase early intimal hyperplasia when clopidogrel is administered. Protecting the vein from ischemia and reperfusion injury preserves ECs.

  13. Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

    International Nuclear Information System (INIS)

    Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time

  14. Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

    Science.gov (United States)

    Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi

    2007-06-01

    Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time.

  15. Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Yuki [Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan)]. E-mail: wada.yuki@jaea.go.jp; Seko, Noriaki [Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Nagasawa, Naotsugu [Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Tamada, Masao [Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Kasuya, Ken-ichi [Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Mitomo, Hiroshi [Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan)

    2007-06-15

    Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time.

  16. Graft modification strategies to improve patency of prosthetic arteriovenous grafts for hemodialysis.

    Science.gov (United States)

    Moufarrej, Andrew; Tordoir, Jan; Mees, Barend

    2016-03-01

    Prosthetic arteriovenous grafts (AVGs) are indicated for vascular access for long-term hemodialysis in patients in whom creation or maintenance of an arteriovenous fistula (AVF) has failed or is contraindicated. AVGs have an inferior long-term patency as compared to AVFs. To ameliorate patency rates of prosthetic AVGs, different strategies have emerged to improve graft materials. This review aims to describe current strategies and future perspectives on graft modification, by graft geometry, drug coatings and graft surface technology, to improve AVG patency. PMID:26951913

  17. Use of autologous bone graft in anterior cervical decompression: morbidity & quality of life analysis.

    LENUS (Irish Health Repository)

    Heneghan, Helen M

    2009-01-01

    BACKGROUND: Autologous iliac crest graft has long been the gold standard graft material used in cervical fusion. However its harvest has significant associated morbidity, including protracted postoperative pain scores at the harvest site. Thus its continued practice warrants scrutiny, particularly now that alternatives are available. Our aims were to assess incidence and nature of complications associated with iliac crest harvest when performed in the setting of Anterior Cervical Decompression (ACD). Also, to perform a comparative analysis of patient satisfaction and quality of life scores after ACD surgeries, when performed with and without iliac graft harvest. METHODS: All patients who underwent consecutive ACD procedures, with and without the use of autologous iliac crest graft, over a 48 month period were included (n = 53). Patients were assessed clinically at a minimum of 12 months postoperatively and administered 2 validated quality of life questionnaires: the SF-36 and Cervical Spine Outcomes Questionnaires (Response rate 96%). Primary composite endpoints included incidence of bone graft donor site morbidity, pain scores, operative duration, and quality of life scores. RESULTS: Patients who underwent iliac graft harvest experienced significant peri-operative donor site specific morbidity, including a high incidence of pain at the iliac crest (90%), iliac wound infection (7%), a jejunal perforation, and longer operative duration (285 minutes vs. 238 minutes, p = 0.026). Longer term follow-up demonstrated protracted postoperative pain at the harvest site and significantly lower mental health scores on both quality of life instruments, for those patients who underwent autologous graft harvest CONCLUSION: ACD with iliac crest graft harvest is associated with significant iliac crest donor site morbidity and lower quality of life at greater than 12 months post operatively. This is now avoidable by using alternatives to autologous bone without compromising clinical

  18. Grafted polyelectrolyte membranes for lithium batteries and fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, John B.

    2003-06-24

    Polyelectrolyte materials have been developed for lithium battery systems in response to the severe problems due to salt concentration gradients that occur in composite electrodes (aka membrane-electrode assemblies). Comb branch polymer architectures are described which allow for grafting of appropriate anions on to the polymer and also for cross-linking to provide for appropriate mechanical properties. The interactions of the polymers with the electrode surfaces are critical for the performance of the system and some of the structural features that influence this will be described. Parallels with the fuel cell MEA structures exist and will also be discussed.

  19. Preparation of High Density Polyethylene/Waste Polyurethane Blends Compatibilized with Polyethylene-Graft-Maleic Anhydride by Radiation

    Directory of Open Access Journals (Sweden)

    Jong-Seok Park

    2015-04-01

    Full Text Available Polyurethane (PU is a very popular polymer that is used in a variety of applications due to its good mechanical, thermal, and chemical properties. However, PU recycling has received significant attention due to environmental issues. In this study, we developed a recycling method for waste PU that utilizes the radiation grafting technique. Grafting of waste PU was carried out using a radiation technique with polyethylene-graft-maleic anhydride (PE-g-MA. The PE-g-MA-grafted PU/high density polyethylene (HDPE composite was prepared by melt-blending at various concentrations (0–10 phr of PE-g-MA-grafted PU. The composites were characterized using fourier transform infrared spectroscopy (FT-IR, and their surface morphology and thermal/mechanical properties are reported. For 1 phr PU, the PU could be easily introduced to the HDPE during the melt processing in the blender after the radiation-induced grafting of PU with PE-g-MA. PE-g-MA was easily reacted with PU according to the increasing radiation dose and was located at the interface between the PU and the HDPE during the melt processing in the blender, which improved the interfacial interactions and the mechanical properties of the resultant composites. However, the elongation at break for a PU content >2 phr was drastically decreased.

  20. Radiation graft modification of EPDM rubber

    Science.gov (United States)

    Katbab, A. A.; Burford, R. P.; Garnett, J. L.

    N-Vinyl pyrrolidone (NVP), 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) have been grafted to the surface of rubber vulcanizates based on ethylene-propylene-terpolymer (EPDM) using the simultaneous radiation method to alter surface properties such as wettability and therefore biocompatibility. The effect of monomer concentration, solvent and EPDM structural factors on the grafting behavior have been investigated. The inhibitory effect upon homopolymerization of various salts has also been evaluated for the three monomers. NVP and HEMA could be grafted onto EPDM rubber in the presence of aqueous solutions of cupric nitrate at 0.005 M and 1.0 M concentrations respectively. Aqueous solutions of Mohr's salt (ammonium ferrous sulphate) at 0.05 M not only suppressed the homopolymerization of AAm but also increased grafting yield. The percentage grafting also increased with increasing AAm concentration. A mechanism has been proposed to explain the behaviour of these monomers. The inclusion of multifunctional acrylates in additive amounts (1.0 vol%) enhanced the graft degree. Modified samples were able to be efficiently stained, allowing the depth of the graft copolymerization to be determined by light microscopy. Water was found to have an accelerating effect on the polymerization of these monomers, but methanol prevented their polymerization completely. The effect of EPDM structural factors upon degree of grafting was found to vary, depending upon the monomer type.

  1. Small parietal thrombi in artificial bypass grafts

    International Nuclear Information System (INIS)

    During the last five years, 51 femoro-popliteal polytrafluoroethylene grafts were implanted in patients in the Second Surgical University Clinic, Vienna. In four of these patients an angiogram performed shortly after operation showed numerous small parietal thrombi on the artificial graft, a review of the literature has not shown any similar reports. The clinical importance and consequences of this observation are discussed. (orig.)

  2. Economics of grafted vs conventional watermelon plants

    Science.gov (United States)

    Grafting of watermelons has been used in many countries to provide control of, or resistance to, certain soil borne diseases such as Fusarium wilt. The impact of grafting on postharvest quality has not been thoroughly examined. This report deals with the comparison of the costs of production betwe...

  3. Graft copolymers obtained by radiation grafting of methacrylic acid onto polypropylene films

    International Nuclear Information System (INIS)

    Direct radiation grafting of methacrylic acid (MAA) onto polypropylene films (PP) was studied. The effect of different solvents such as benzene, distilled water, dimethyl formamide, isopropanol, isopropanol/water-mixture, on the swelling and the grafting process of MAA onto (PP) films was investigated. It was found that the grafting process was enhanced under vacuum irradiation in benzene as a diluent for MAA as compared with other solvents examined. The dependence of the grafting rate on such monomer concentrations was found to be 1.2 order. The relationship between the grafting rate and film thickness gave a negative first order dependence. This grafting system proceeded by a diffusion controlled process. Some selected properties of the grafted films such as mechanical and electrical properties, swelling behaviour, and gel determination, were also investigated. (author)

  4. Ex vivo lung graft perfusion.

    Science.gov (United States)

    Briot, Raphaël; Gennai, Stéphane; Maignan, Maxime; Souilamas, Redha; Pison, Christophe

    2016-04-01

    This review proposes an update of the state of the art and the ongoing clinical trials of ex vivo lung perfusion for lung transplantation in patients. Ex vivo lung perfusion techniques (EVLP) can be used to evaluate a lung graft outside of the body. The goal of EVLP is to study the functional status of lung grafts that were first rejected for transplantation because they did not match all criteria for a conventional transplantation. After an EVLP evaluation, some of these lungs may be requalified for a possible transplantation in patients. This article proposes an overview of the developments of EVLP techniques. During EVLP, the perfusion and ventilation of the isolated lung preparation are very progressive in order to avoid oedema due to ischaemia-reperfusion injuries. Lung evaluation is mainly based on gasometric (PaO2/FiO2) and rheological criteria (low pulmonary arterial resistance). Several series of patients transplanted with EVLP evaluated lungs have been recently published with promising results. EVLP preparations also allow a better understanding of the physiopathology and treatments of ischaemia-reperfusion injuries. Organ procurements from "non-heart-beating" donors will probably require a wider application of these ex vivo techniques. The development of semi-automated systems might facilitate the clinical use of EVLP techniques. PMID:26746565

  5. [Indices of intraoperative flowmetry, determining patency of grafts in the remote period after revascularization of the right coronary artery].

    Science.gov (United States)

    Bazylev, V V; Nemchenko, E V; Pavlov, A A; Karnakhin, V A

    2016-01-01

    The authors studied the threshold values of ultrasound flowmetry concerning composite T-grafts, combined I-grafts, and autovenous shunts during revascularization of the right coronary artery (RCA), determining high risk for the development of shunt occlusion in the remote postoperative period. The retrospective study included a total of 223 patients subjected to revascularization of the RCA's basin with the help of composite T-grafts, combined I-grafts, and autovenous shunts. Depending on the method of bypass grafting of the RCA and its branches, all patients were subdivided into 3 groups: Group 1 was composed of 65 patients in whom the RCA basin was revascularized by a branch of the composite T-graft, Group 2 comprised 112 patients who endured autovenous aortocoronary bypass grafting, and Group 3 consisted of 46 patients in whom the RCA basin was shunted by a combined mammarovenous I-graft. The groups had no statistically significant differences on the main clinical and demographic parameters. Intraoperative assessment of the blood flow through the coronary shunts was carried out by means of ultrasound flowmetry. The remote results were evaluated based on the findings of the control coronaroshuntography which was carried out in all patients within the terms varying from 16 to 43 months. In the remote period in Group 1 patients (T-graft), 59 (90%) mammary shunts were patent, in Group 2 - 99 (88.4%) autovenous shunts, and in Group 3 (I-graft) 42 (95.5%) shunt were patent. Cumulative probability of freedom from shunt occlusion within the terms up to 3 years after surgery in Group 1 amounted to 82±0.5%, in Group 2 to 58±2.1%, and in Group 3 to 86±1.9%, with the differences between Group 2 and other groups being statistically significant (p=0.01). The Poisson regression analysis showed that the risk for graft occlusion increased by 10% with the resistance index in the branch of the T-graft from 4.0; by 8% with the resistance index in the autovein from 2.9; and by 3

  6. Rootstock scion somatogenetic interactions in perennial composite plants

    OpenAIRE

    Koepke, Tyson; Dhingra, Amit

    2013-01-01

    The ancient plant production practice of grafting which instantly imparts new physiological properties to the desirable scion still remains shrouded in mystery. Yet, grafting remains a widely used technique in the production of several horticultural species. In a composite grafted plant, rootstocks control many aspects of scion growth and physiology including yield and quality attributes as well as biotic and abiotic stress tolerance. Broadly, physical, physiological, biochemical and molecula...

  7. Graft Take-Rates After Tympanoplasty

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Aabenhus, Kristine; Glad, Henrik; Sørensen, Mads Sølvsten

    2014-01-01

    OBJECTIVE: To present a prospective ear surgery database and investigate the graft take-rate and prognostic factors for graft take-rate in tympanoplasty using the database. STUDY DESIGN: Prospective database study. SETTING: Tertiary referral center. PATIENTS: A total of 1606 cases undergoing...... tympanoplasty types I to IV were registered in the database in the period from February 2004 to November 2013. INTERVENTION: A total of 837 cases underwent myringoplasty/tympanoplasty type I. MAIN OUTCOME MEASURE: Graft take-rate and prognostic factors (age, discharge at time of surgery, tuba function......, technique, graft material, and revision surgery) for tympanoplasty type I were studied. A comparison with the graft take-rates for tympanoplasty types II to IV and/or cholesteatoma was made. RESULTS: A user-friendly ear surgery database with fast data entry and direct import of audiometric data was...

  8. Gamma-radiation-induced grafting onto wool

    International Nuclear Information System (INIS)

    Radiation-induced grafting studies have been carried out on loose wool fibres. Different vinyl monomers were used and they were grafted in different solvents which were selected on the basis of their swelling efficiency and solubility parameters. The treatments were performed once with and once without the addition of water. The presence of water caused the polymer uptake to increase considerably. Formic acid/methanol and methanol accelerate the grafting process best, since they have the highest hydrogen-bond interaction efficiency. The moisture uptake of grafted wool decreases. X-ray and differential scanning calorimetry tests show unambiguously that grafting occurs in different morphological areas, depending on the type of polymer. The single fibre studies served as basis for analogous tests on wool fabrics (Part II). (author)

  9. Polyethylene oxide hydration in grafted layers

    Science.gov (United States)

    Dormidontova, Elena; Wang, Zilu

    Hydration of water soluble polymers is one of the key-factors defining their conformation and properties, similar to biopolymers. Polyethylene oxide (PEO) is one of the most important biomedical-applications polymers and is known for its reverse temperature solubility due to hydrogen bonding with water. As in many practical applications PEO chains are grafted to surfaces, e.g. of nanoparticles or planar surfaces, it is important to understand PEO hydration in such grafted layers. Using atomistic molecular dynamic simulations we investigate the details of molecular conformation and hydration of PEO end-grafted to gold surfaces. We analyze polymer and water density distribution as a function of distance from the surface for different grafting densities. Based on a detailed analysis of hydrogen bonding between polymer and water in grafted PEO layers, we will discuss the extent of PEO hydration and its implication for polymer conformation, mobility and layer properties. This research is supported by NSF (DMR-1410928).

  10. Historical and modern genetics of plant graft hybridization.

    Science.gov (United States)

    Liu, Yongsheng

    2006-01-01

    Graft hybridization is a type of asexual hybridization in which heritable changes may be induced by grafting. Darwin was the first to put forward the conception of graft hybridization. The existence of graft hybrids has been extensively documented, although there has been a refusal to accept its reality, other than perceiving the phenomenon as involving "simple" chimeras. Graft hybrids can be divided into two categories--chimera graft hybrid (so-called graft chimera) and nonchimera graft hybrid (so-called vegetative hybrid). These differ with respect to grafting methods, characteristics, and mechanisms proposed to underlie the two categories. Graft hybridization is not only a simple and powerful means of plant breeding but also provides striking evidence in favor of Darwin's notions about Pangenesis--a developmental theory of heredity, on the one hand, and a phenomenon that plays a crucial role in revealing the mystery of non-Mendelian inheritance in grafted fruit trees. PMID:16735156

  11. Effects of carbon nanotubes grafted on a carbon fiber surface on their interfacial properties with the matrix in composites%炭纤维表面接枝碳纳米管对复合材料界面性能的影响

    Institute of Scientific and Technical Information of China (English)

    刘秀影; 宋英; 李存梅; 王福平

    2012-01-01

    采用聚酰胺-胺(PAMAM)树状分子化学修饰方法制备碳纳米管接枝炭纤维(CF-PAMAM-CNTs)新型增强体.利用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和原子力显微镜(AFM)对接枝前后CF表面官能团和表面形貌进行表征;利用接触角测量、单丝拉伸方法研究了接枝前后纤维单丝的润湿性能及拉伸强度,并通过微脱黏法分析了其复合材料的界面剪切强度,同时探索了CNTs的最佳接枝量.结果表明,当CNTs接枝量为15%时,CF表面粗糙度提高了180%,表面能提高了300%,拉伸强度提高了22%,复合材料的界面剪切强度提高了178%,这表明CNTs接枝有利于改善CF复合材料的界面性能.%Carbon fibers (CFs) were oxidized by concentrated HNO3 and then reacted with polyamidoamine dendrimers (PAMAM) with an average molecular weight of 157 to form CF-PAMAM. The CF-PAMAM was further reacted with oxidized carbon nanotubes (CNTs) to form CF-PAMAM-CNTs that were used as the reinforcement for epoxy resin-based composites. The functional groups and structure of the CF-PAMAM-CNTs were examined by XPS, SEM and AFM, and their wettability and the tensile strength were investigated by contact angle measurements and single strand extension respectively. The interfacial shear strength of the composites was measured by a micro-debonding method. Results showed that, compared with CFs, the surface roughness, surface energy and tensile strength of the CF-PAMAM-CNTs were increased by 180% , 300% and 22% , respectively when the CNT content was 15 mass% . The interfacial shear strength of the composite reinforced with CF-PAMAM-CNTs was increased by 178% for the same CNT content, which showed that the grafted nanotubes improved the interfacial properties of the filler with the matrix.

  12. Inflorescence stem grafting made easy in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Nisar Nazia

    2012-12-01

    Full Text Available Abstract Background Plant grafting techniques have deepened our understanding of the signals facilitating communication between the root and shoot, as well as between shoot and reproductive organs. Transmissible signalling molecules can include hormones, peptides, proteins and metabolites: some of which travel long distances to communicate stress, nutrient status, disease and developmental events. While hypocotyl micrografting techniques have been successfully established for Arabidopsis to explore root to shoot communications, inflorescence grafting in Arabidopsis has not been exploited to the same extent. Two different strategies (horizontal and wedge-style inflorescence grafting have been developed to explore long distance signalling between the shoot and reproductive organs. We developed a robust wedge-cleft grafting method, with success rates greater than 87%, by developing better tissue contact between the stems from the inflorescence scion and rootstock. We describe how to perform a successful inflorescence stem graft that allows for reproducible translocation experiments into the physiological, developmental and molecular aspects of long distance signalling events that promote reproduction. Results Wedge grafts of the Arabidopsis inflorescence stem were supported with silicone tubing and further sealed with parafilm to maintain the vascular flow of nutrients to the shoot and reproductive tissues. Nearly all (87% grafted plants formed a strong union between the scion and rootstock. The success of grafting was scored using an inflorescence growth assay based upon the growth of primary stem. Repeated pruning produced new cauline tissues, healthy flowers and reproductive siliques, which indicates a healthy flow of nutrients from the rootstock. Removal of the silicone tubing showed a tightly fused wedge graft junction with callus proliferation. Histological staining of sections through the graft junction demonstrated the differentiation of

  13. Characteristic study of pre-irradiated HDPE grafted with NIPA/AAc

    International Nuclear Information System (INIS)

    HDPE preirradiated under nitrogen protection was grafted with NIPA/AAc. The grafted hydrogel is temperature and pH sensitive. FTIR, DSC, SEM were used to study the composition, properties and surface morphology of the hydrogel. Results showing that LCST characteristics was different under different pH environment. Under acid condition, hydrogel volume increased with increasing temperature, indicating the hydrogel being heat expansive and temperature sensitive. Under neutral or alkaline condition, hydrogel volume contracted rapidly near phase transition with increasing temperature, indicating the hydrogel being heat shrinking and temperature sensitive. (authors)

  14. Radiation modified filler for dental restorative composites

    International Nuclear Information System (INIS)

    Gamma-radiation was utilized to graft acrylic acid in the vapor phase to the surface of glass fibers and quartz particles. This treatment improved the wettability of the filler with the polymeric matrix and enhanced the mechanical properties of the composite. Samples were prepared from the unfilled dental resin, and from composites containing untreated, silane treated and polyacrylic acid-grafted fillers. These composites contained 30, 45 and 69 vol.% filler in each category. The composites containing grafted filler were superior in hardness and compressive strength, and equivalent in abrasion resistance to those with silane treated fillers. However, both treatments showed at least a 50% improvement in compressive strength and a 300% reduction in wear over composites with untreated filler. This improvement was even more substantial when glass fibers were used as the filler material. (author)

  15. Gradient Poly(styrene-co-polyglycidol) Grafts via Silicon Surface-Initiated AGET ATRP.

    Science.gov (United States)

    Gosecka, Monika; Pietrasik, Joanna; Decorse, Philippe; Glebocki, Bartosz; Chehimi, Mohamed M; Slomkowski, Stanislaw; Basinska, Teresa

    2015-05-01

    Gradient copolymer grafts of styrene and α-tert-butoxy-ω-vinylbenzyl-poly(glycidol ethoxyethyl ether) (PGLet), a precursor of α-tert-butoxy-ω-vinylbenzyl-polyglycidol macromonomer (PGL), were prepared on silicon wafers via a surface-initiated activator generated by electron transfer radical polymerization (AGET ATRP). Silicon plates with previously attached 2-bromoisobutyrate served as a macroinitiator for the AGET ATRP (activator generated by electron transfer) of styrene and PGLet. The copolymers' gradient P(S-co-PPGL) of composition and thickness was obtained by a simple method where the plates were slowly removed from reaction mixture using a step motor. PGLet was added continuously (dropwise) into the reactor during withdrawal of the plates from solution in order to increase the relative concentration of PGLet in polymerization mixture. A range of strategies of making grafts was tested. The plates with copolymers grafts were analyzed by various techniques, like XPS, ellipsometry, and FTIR spectroscopy. The results indicate that the AGET ATRP process is dependent on the styrene/PGLet macromonomer ratio in the polymerization mixture. Under optimal conditions, the addition of PGLet during polymerization and subsequent deprotection of hydroxyl groups of PGLet permit to obtain plates with a novel copolymer layer with composition, thickness, and wettability gradient. Plates with chemical composition of copolymer grafts gradient served as versatile supports with controlled hydrophilic/hydrophobic area and were suitable for tailored deposition of particles. PMID:25871942

  16. Radiation grafting of pH-sensitive acrylic acid and 4-vinyl pyridine onto nylon-6 using one- and two-step methods

    International Nuclear Information System (INIS)

    Acrylic acid (AAc) and 4-vinyl pyridine (4VP) were γ-ray grafted onto nylon-6 (Ny6) films via pre-irradiation oxidative method. These monomers were grafted using a one-step method to render Ny6-g–(AAc/4VP). A two-step or sequential method was used to render (Ny6-g–AAc)-g–4VP. Random copolymer branches were obtained when the grafting was carried out via one-step method using the two monomers together. The two-step method was applied to graft chains of 4VP on both Ny6 substrate and previously grafted AAc chains (Ny6-g–AAc). The two types of binary copolymers synthesized were characterized to determine the amount of grafted polymers, the thermal behavior (DSC and TGA), the surface composition (XPS), and the pH responsiveness. In the two-step process, it is possible to achieve a higher graft yield, better control of the amount of each monomer, good reversibility in the swelling/deswelling process and shorter time to achieve equilibrium swelling. - Highlights: • A new binary graft of 4VP and AAc onto Ny6 films was synthesized by γ-radiation. • The binary grafted material has potential application for heavy ion retention. • The two-step method shows better conditions in swelling and reversibility properties. • Surface distribution of monomers was evaluate by XPS characterization

  17. Synthesis and characterization of nanoscale polymer films grafted to metal surfaces

    Science.gov (United States)

    Galabura, Yuriy

    the Si/SiO2/Au microprinted electrodes. The polymer layers insulated under normal ambient conditions can display a significant increase in conductivity as the environment changes. Namely, we demonstrate that the in-plane electrical conductivity of the grafted polymer layers grafted to Au and SiO2 surfaces can be changed by at least two orders of magnitude upon exposure to water or organic solvent vapors. The conductive properties of all the grafted polymer films under study are also significantly enhanced with temperature increase. The observed phenomenon makes possible the chemical design of polymer nanoscale layers with reduced or enhanced sensitivity to anticipated changes in environmental conditions. Finally, we show that the observed effects can be used in a micron-sized conductometric-transducing scheme for the detection of volatile organic solvents. This research also includes the study of nanoscale-level actuation with grafted polymer films and polymer/gold nanoparticles systems-grafted composites. First, we investigate the nanoscale-level actuation with polymer films. To this end, we use "grafting to" approach to synthesize PGMA thin polymer film (80-200 nm). Then, film is swollen in a good solvent and freeze-dried until the solvent is sublimated, thereby creating grafted polymer nanofoam that exhibits shape memory properties. We demonstrate nanoscale actuation using the developed system. In addition, we show that the modification of the PGMA nanofoam with low molecular weight polystyrene allows response tuning of the porous polymer film. Furthermore, we incorporate gold nanoparticles (5 nm) into a thin PGMA layer (80 nm) to fabricate a PGMA/gold nanoparticles grafted composite film. The PGMA/gold nanoparticles grafted nanofoam is synthesized following the same procedure developed for the fabrication of the PGMA nanofoam. We demonstrate the shape-memory properties and nanoscale-level actuation of the developed system. Moreover, we investigate the change in

  18. Hemodynamics Simulation of Stenosed Coronary Bypass Graft

    Institute of Scientific and Technical Information of China (English)

    LIU You-jun; QIAO Aike; DU Jian-jun

    2005-01-01

    By means of FEM, the physiological blood flow in coronary bypass graft is simulated. The stenosis in coronary artery is involved in the graft model,and the deformation of graft end to allow the surgical suture with a smaller diameter coronary is taken into consideration. The flow pattern, secondary flow and wall shear stress in the vicinity of anastomosis are analyzed. It is shown that a zone of low wall stress and high wall stress gradient exists downstream the toe. The floor opposed to the anastomosis is an area of high wall stress and high wall stress gradient. Both the toe downstream and the anastomosis bottom floor are prone to intimal hyperplasia.

  19. Flow characteristics in narrowed coronary bypass graft

    Science.gov (United States)

    Bernad, S. I.; Bosioc, A.; Bernad, E. S.; Petre, I.; Totorean, A. F.

    2016-06-01

    Tortuous saphenous vein graft (SVG) hemodynamics was investigated using computational fluid dynamics (CFD) techniques. Computed tomography (CT) technology is used for non-invasive bypass graft assessment 7 days after surgery. CT investigation shown two regions with severe shape remodelling first is an elbow type contortion and second is a severe curvature with tortuous area reduction. In conclusion, the helical flow induced by vessel torsion may stabilize the blood flow in the distal part of the SVG, reducing the flow disturbance and suppressing the flow separation, but in the distal end of the graft, promote the inflammatory processes in the vessels.

  20. Immunohistochemical localization of IAA in graft union of explanted internode grafting

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The dynamic changes of IAA in graft union of explanted internode autografting of Cucumber (Cucumis sativus Linn.) have been investigated using the immunohistochemical localization technique.It is shown that the efficiency of IAA fixation using lyophilization-gas fixation is higher than that using liquid chemical fixation.In contrast to few silver particles and no significant changes during the development of graft union cultured in hormone-free medium,more silver particles in graft union and significant changes of IAA related to graft union development have been found when graft union was cultured in medium supplemented with appropriate hormones.The fixation procedure of plant hormones and the roles of IAA in graft union are discussed.

  1. The effect of pH on grafting yield in polyethylene radiation grafting system

    International Nuclear Information System (INIS)

    Acrylic acid (AA) and sodium styrene sulfonate (SSS) were grafted onto high-density polyethylene film by preirradiation, and the authors prepared an ion exchange membrane including strong acid and weak acid groups. The effect of pH on grafting yield was studied. In simultaneous radiation method Gt and Gs decrease with pH either HDPE grafted AA and SSS or AA-g-HDPE membrane grafted SSS. In preirradiation method Gt and Gs respectively increase with pH, and the highest grafting yield was observed at pH=2.80 then Gt and Gs decrease with pH. Viscidity of grafting system was changed due to adjusting of pH, so that diffuse rate of monomers into matrix was affected

  2. Grafted cellulose for PAHs removal present in industrial discharge waters

    Science.gov (United States)

    Euvrard, Elise; Druart, Coline; Poupeney, Amandine; Crini, Nadia; Vismara, Elena; Lanza, Tommaso; Torri, Giangiacomo; Gavoille, Sophie; Crini, Gregorio

    2014-05-01

    , the grafted cellulose showed lower adsorption capacities of PAHs (about 40% for the total PAH content) when they were in real effluents than they were in synthetic solutions. However, it was observed that PAH composition in discharge waters was different than in synthetic solutions, qualitatively and quantitatively. Despite the presence of numerous other substances in industrial effluents at high concentrations (for instance metals equal to mg/L and salts to g/L), the grafted cellulose was demonstrated as suitable to remove organic substances at trace levels like PAHs (equal to ng/L). Reference: [1] Vismara E., Melone L., Gastaldi G., Cosentino C., Torri G. J. Hazardous Mat. 170 (2009) 798-808. Acknowledgements: The authors thank Agence de l'Eau, FEDER and the Conseil regional de Franche-Comté for financial support (NIRHOFEX Program).

  3. Synthesis and characterization of macromolecular layers grafted to polymer surfaces

    Science.gov (United States)

    Burtovyy, Oleksandr

    The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility. Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to polymer substrates. Specifically, attachment of functional polymers via a "grafting to" approach has been extensively studied using PET and nylon model substrates. First, poly(glycidyl methacrylate) was used to introduce permanent functionalities to the model substrates by anchoring it to model films. Then, three different functional polymers were grafted on top of the previous layer. As one part of this study, the temperature and time dependence of grafting functional layers were studied. The surface coverage by hydrophobic polymer was determined from experimental data and predicted by a model. In general, the model has a high degree of predictive capability. Next, surface modification of polymeric fibers and membranes is presented as an important application of the polymer thin layers targeted in the study. Specifically, the procedures developed for surface modification of model substrates was employed for modification of PET, nylon, and cotton fabrics as well as PET track-etched membranes. Since epoxy groups are highly reactive in various chemical reactions, the approach becomes virtually universal, allowing both various surfaces and end-functionalized macromolecules to be used in the grafted layer synthesis. PET

  4. The use of radiation-induced graft polymerization for modification of polymer track membranes

    International Nuclear Information System (INIS)

    Track membranes (TM) made of poly(ethylene terephtalate) (PET) and polypropylene (PP) films have a number of peculiarities as compared with other ones. They have high mechanical strength at a low thickness, narrow pore size distribution, low content of extractables. However, TM have some disadvantages such as low chemical resistance in alkaline media (PET TM), the low water flow rate due to the hydrophobic nature of their surface. The use of radiation-induced graft polymerization makes it possible to improve the basic characteristics of TM. In this communication our results on the modification of PET and PP TM are presented. The modified membranes were prepared by radiation-induced graft polymerization from the liquid phase. Three methods of grafting were used: (a) the direct method in argon atmosphere; (b) the pre-irradiation of TM in air followed by grafting in argon atmosphere; (c) pre-irradiation in vacuum followed by grafting in vacuum without contacting oxygen. The aim of the work was to investigate some properties of TM modified by grafted poly(methylvinyl pyridine) (PMVP) and poly(N-isopropylacrylamide) (PNIPAAM). It was shown that the modification of TM with hydrophilic polymer results in the growth of the water flow rate. In the past few years many works have been devoted to the synthesis of new polymers - the so-called 'intelligent' materials - such as PNIPAAM. However, it is very difficult to make thin membranes of this polymer. Recently, it has been proposed to manufacture composite membranes by grafting stimulus-responsive polymers onto TM. Following this principle, we prepared thermosensitive membranes by the radiation-induced graft polymerization of N-isopropylacrylamide (NIPAAM) onto PET TM. PET TM with the pore size of about 1 μm and pore density of 106 cm-2 were first inserted into a solution of NIPAAM containing inhibitor of homopolymerization (CuCl2) and then exposed to the γ-rays from a 60Co source. The transport properties of the grafted TM

  5. The use of radiation-induced graft polymerization for modification of polymer track membranes

    Science.gov (United States)

    Shtanko, N. I.; Kabanov, V. Ya.; Apel, P. Yu.; Yoshida, M.

    1999-05-01

    Track membranes (TM) made of poly(ethylene terephtalate) (PET) and polypropylene (PP) films have a number of peculiarities as compared with other ones. They have high mechanical strength at a low thickness, narrow pore size distribution, low content of extractables. However, TM have some disadvantages such as low chemical resistance in alkaline media (PET TM), the low water flow rate due to the hydrophobic nature of their surface. The use of radiation-induced graft polymerization makes it possible to improve the basic characteristics of TM. In this communication our results on the modification of PET and PP TM are presented. The modified membranes were prepared by radiation-induced graft polymerization from the liquid phase. Three methods of grafting were used: (a) the direct method in argon atmosphere; (b) the pre-irradiation of TM in air followed by grafting in argon atmosphere; (c) pre-irradiation in vacuum followed by grafting in vacuum without contacting oxygen. The aim of the work was to investigate some properties of TM modified by grafted poly(methylvinyl pyridine) (PMVP) and poly(N-isopropylacrylamide) (PNIPAAM). It was shown that the modification of TM with hydrophilic polymer results in the growth of the water flow rate. In the past few years many works have been devoted to the synthesis of new polymers - the so-called "intelligent" materials - such as PNIPAAM. However, it is very difficult to make thin membranes of this polymer. Recently, it has been proposed to manufacture composite membranes by grafting stimulus-responsive polymers onto TM. Following this principle, we prepared thermosensitive membranes by the radiation-induced graft polymerization of N-isopropylacrylamide (NIPAAM) onto PET TM. PET TM with the pore size of about 1 μm and pore density of 10 6 cm -2 were first inserted into a solution of NIPAAM containing inhibitor of homopolymerization (CuCl 2) and then exposed to the γ-rays from a 60Co source. The transport properties of the grafted

  6. Assessment of Bonelike (registered) graft with a resorbable matrix using an animal model

    International Nuclear Information System (INIS)

    Synthetic bone grafts have been developed to provide an alternative to autografts and allografts. Bonelike (registered) is a patented synthetic osteoconductive bone graft that mimics the mineral composition of natural bone. In the present preliminary animal studies a user-friendly version of synthetic bone graft Bonelike (registered) have been developed by using a resorbable matrix, Floseal (registered) , as a vehicle and raloxifene hydrochloride as a therapeutic molecule, that is known to decrease osteoclast activity and therefore enhanced bone formation. From histological and scanning electron microscopy evaluations, the use of Bonelike (registered) associated with Floseal (registered) and raloxifene hydrochloride showed that new bone was rapidly apposed on implanted granules and also that the presence of the matrix and therapeutic molecule does not alter the proven highly osteoconductivity properties of Bonelike (registered) . Therefore, this association may be one step-forward for the clinical applications of Bonelike (registered) scaffolds since it is much more easy-to-handle when compared to granular materials

  7. Assessment of Bonelike (registered) graft with a resorbable matrix using an animal model

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, J.V. [CHVNG-Servico de Estomatologia, Centro Hospitalar de Vila Nova de Gaia (Portugal); ICBAS-Instituto de Ciencias Biomedicas de Abel Salazar, Universidade do Porto, Largo Professor Abel Salazar, 2, 4099-003 Porto (Portugal); CECA/ICETA-Centro de Estudos de Ciencia Animal, Instituto de Ciencias e Tecnologias Agrarias e Agro-Alimentares, Campus Agrario de Vairao, Rua Padre Armando Quintas, 4485-661 Vairao (Portugal); Hussain, N. Sooraj [INEB-Instituto de Engenharia Biomedica, Laboratorio de Biomateriais, Rua Campo Alegre, 823, 4150-180, Porto (Portugal); FEUP-Faculdade de Engenharia da Universidade do Porto, DEMM, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Botelho, C.M. [INEB-Instituto de Engenharia Biomedica, Laboratorio de Biomateriais, Rua Campo Alegre, 823, 4150-180, Porto (Portugal); FEUP-Faculdade de Engenharia da Universidade do Porto, DEMM, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Mauricio, A.C. [ICBAS-Instituto de Ciencias Biomedicas de Abel Salazar, Universidade do Porto, Largo Professor Abel Salazar, 2, 4099-003 Porto (Portugal); CECA/ICETA-Centro de Estudos de Ciencia Animal, Instituto de Ciencias e Tecnologias Agrarias e Agro-Alimentares, Campus Agrario de Vairao, Rua Padre Armando Quintas, 4485-661 Vairao (Portugal); Afonso, A. [FMDUP-Faculdade de Medicina Dentaria da Universidade do Porto, Rua Dr. Manuel Pereira da Silva, 4200-393 Porto (Portugal); Ali, N. [Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Santos, J.D. [INEB-Instituto de Engenharia Biomedica, Laboratorio de Biomateriais, Rua Campo Alegre, 823, 4150-180, Porto (Portugal) and FEUP-Faculdade de Engenharia da Universidade do Porto, DEMM, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: jdsantos@fe.up.pt

    2006-09-25

    Synthetic bone grafts have been developed to provide an alternative to autografts and allografts. Bonelike (registered) is a patented synthetic osteoconductive bone graft that mimics the mineral composition of natural bone. In the present preliminary animal studies a user-friendly version of synthetic bone graft Bonelike (registered) have been developed by using a resorbable matrix, Floseal (registered) , as a vehicle and raloxifene hydrochloride as a therapeutic molecule, that is known to decrease osteoclast activity and therefore enhanced bone formation. From histological and scanning electron microscopy evaluations, the use of Bonelike (registered) associated with Floseal (registered) and raloxifene hydrochloride showed that new bone was rapidly apposed on implanted granules and also that the presence of the matrix and therapeutic molecule does not alter the proven highly osteoconductivity properties of Bonelike (registered) . Therefore, this association may be one step-forward for the clinical applications of Bonelike (registered) scaffolds since it is much more easy-to-handle when compared to granular materials.

  8. Tuning mechanical properties of polymer-grafted nanoparticle networks by using biomimetic catch bonds

    Science.gov (United States)

    Mbanga, Badel L.; Iyer, Balaji V. S.; Yashin, Victor V.; Balazs, Anna C.

    Cross-linked networks of polymer-grafted nanoparticles (PGNs) constitute a class of composites with tunable mechanical properties that exhibit a self-healing behavior. A PGN network consists of nanoparticles that are decorated with end-grafted polymer chains. Reactive groups on the free ends of these grafted chains can form bonds with the chain ends on the nearby particles. We study these materials using a 3D computational model that encompasses the particle-particle interactions, the kinetics of bond formation and rupture, and the external forces applied to the network. In our model, a fraction of cross-links is formed through biomimetic ``catch'' bonds. In contrast to conventional ``slip'' bonds, catch bonds can effectively become stronger under a deformation. We show that by varying the fraction of these catch bonds in the network, the toughness, ductility, and tensile strength of the material could be tuned to desired levels.

  9. A simple and rapid method to graft hydroxyapatite on carbon nanotubes

    International Nuclear Information System (INIS)

    Herein a simple and effective approach is introduced to functionalize single walled carbon nanotubes (SWCNTs) by in-situ grafting of hydroxyapatite (HA). The pristine SWCNTs were chemically activated through introduction of carboxylic groups on their surfaces by refluxing in the mixture of H2SO4 and HNO3. The resulting carboxylated SWCNTs were further utilized for grafting of HA. The Fourier transform infrared and Raman spectroscopic studies demonstrated the formation of HA and its grafting over SWCNTs. The phase composition of HA and existence Ca2+ and PO43- ions were studied using X-ray diffraction and energy dispersive X-ray analyses, respectively. The surface morphology of functionalized SWCNTs was analyzed using scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis confirmed the existence of HA on SWCNTs by exhibiting different thermogram for pure HA and functionalized SWCNTs. Overall, this method produced uniform grafting of low crystalline HA on carboxylated SWCNTs with strong interfacial bonding. - Graphical abstract: A facile approach is demonstrated for effective functionalization of single walled carbon nanotubes (SWCNTs) by in-situ grafting of hydroxyapatite (HA) to improve hydrophilicity and biocompatibility of SWCNTs. This method produced uniform grafting of low crystalline HA on carboxylated SWCNTs with strong interfacial bonding. Research highlights: → This method is facile and effective to graft HA on SWCNTs. → As f-SWCNTs is a promising biomaterial to use without any further processing → This technique is economic, easy to repeat and can be optimized for mass production. → Ratio of Ca to P in f-SWCNTs was 1.65, which is near to ratio present in bone tissue.

  10. Separation of several alcohol-benzene mixtures by pervaporation through styrene graft polyethylene membranes

    International Nuclear Information System (INIS)

    The permeation of pure liquids, such as methanol, ethanol, 1-propanol, 2-propanol and benzene, and the permeability and selectivity of 50 vol% binary mixtures of these alcohols and benzene were investigated by pervaporation technique. The used membranes (21%, 40%, and 72% graftings) were obtained by graft polymerization of styrene to polyethylene film (thickness 10 μm) by γ-radiation. The permeation rates of each of these alcohols and benzene were measured by pervaporation through the graft membranes. Those of these alcohols were very small as well as those through the original membrane. On the other hand, the permeabilities for benzene through the graft membranes were larger than that through the original membrane. The temperature dependence of the permeation rate for benzene was expressed by Arrhenius-type relationships, and the apparent activation energies were calculated to be 10.7 (21%), 10.2 (40%) and 10.0 (72%) kcal/mol. In the permeation of 50 vol% several alcohol-benzene mixtures, the permeabilities through the graft membranes were also larger than that through the original membrane, and increased with the grafting. The temperature dependence of the permeation for these mixtures was showed by Arrhenius relationships, and the apparent activation energies were calculated to be in the range of 8.4∼11.0 kcal/mol. The separation factors of the graft membranes calculated from composition of the permeates were always smaller than that of the original membrane, but became larger with increase of molecular volume of alcohol in alcohol-benzene mixtures. (author)

  11. 静电纺丝法制备胆固醇-g-聚乳酸液晶/聚乳酸复合纳米纤维膜%Preparation of Cholesterol-graft-poly ( D, L-lactic acid ) /Poly (D, L-lactic acid) Composite Nanofiber Membranes by Electrospinning

    Institute of Scientific and Technical Information of China (English)

    罗丙红; 李建华; 杨静; 徐宠恩; 田金环; 周长忍

    2012-01-01

    以辛酸亚锡为催化剂,胆固醇(CHOL)为共引发剂引发D,L-丙交酯开环聚合,制备了胆固醇-g-聚(D,L-乳酸)(CHOL-g-PDLLA)低聚物,采用偏光显微镜(POM)和差示扫描量热(DSC)方法考察了其液晶特性.通过静电纺丝技术制备了CHOL/PDLLA和CHOL-g-PDLLA/PDLLA复合纳米纤维膜,对其形貌、界面相容性、孔隙率、拉伸性能和细胞相容性进行了研究.结果表明,CHOL-g-PDLLA为一种热致胆甾型液晶,液晶温度区间为21.8~74.5℃;CHOL-g-PDLLA/PDLLA复合纳米纤维膜的纤维形态良好,表面均匀光滑,孔隙率在70% ~ 75%之间,且其界面相容性优于相应的CHOL/PDLLA.随着CHOL和CHOL-g-PDLLA含量的增加,复合纳米纤维膜的拉伸强度逐渐下降,但CHOL-g-PDLLA/PDLLA复合纳米纤维膜的拉伸强度显著大于CHOL/PDLLA.体外骨髓间充质干细胞培养结果显示,CHOL-g-PDLLA/PDLLA复合纳米纤维膜具有良好的细胞相容性,且优于相应的PDLLA和CHOL/PDLLA纳米纤维膜.%Cholesterol-graft-poly (D,L-lactic acid) (CHOL-g-PDLLA ) oligomer was synthesized by the ring-opening polymerization of D, L-lactide using stannous 2-ethylhexanoate as catalyst and cholesterol (CHOL) as co-initiator, and the liquid crystalline properties was observed by polarizing microscope and differential scanning calorimetry. Then, CHOL/PDLLA and CHOL-g-PDLLA/PDLLA composite nanofiber membranes were prepared by electrospinning. The micrograph, interfacial compatibility, porosity, tensile properties and cellular compatibility of the composite nanofiber membranes were studied. The results show that CHOL-g-PDLLA is a thermotropic cholesteric liquid crystal with liquid crystal temperature range of 21.8-74.5℃. CHOL-g-PDLLA/PDLLA composite nanofiber membranes with good fiber micrograph, smooth surface and porosity of 70% to 75% were obtained, and the interfacial compatibility was significantly better than that of CHOL/ PDLLA. With the content of CHOL or CHOL-g-PDLLA increased

  12. Kinetic and mechanism of radiation-induced graft copolymerization for two grafting systems

    International Nuclear Information System (INIS)

    The graft copolymerization of glycidyl methacrylate (GMA) and vinylbenzyl chloride (VBC) onto nylon fiber was investigated by the pre-irradiation method using electron beam. The effects of grafting parameters, such as monomer concentration, absorbed dose and reaction temperature were investigated. The empirical kinetic rate equations: dG0/ dt = k(Mg0)1.14(Ag)0.52 and dG0/dt = k(Mv0)0.86(Av)1.06, were used to describe grafting of GMA and VBC, respectively. The overall activation energy for graft copolymerization of GMA and VBC were found to be 5.4 and 22.6 kJ/mol, respectively. The results revealed that the grafting kinetics in the two grafting systems were both controlled by the amounts of trapped radicals and monomer molecules. The grafting of GMA onto nylon-6 fibers was found to exhibit higher dependency on the quantity of monomer molecules available, whereas the VBC grafting system was found to exhibit higher dependency on the quantity of trapped radicals. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to provide evidence for the formation of graft copolymers. (author)

  13. Radiation-induced grafting onto wool

    International Nuclear Information System (INIS)

    Radiation-induced grafting tests were done on single wool fibres. Different vinyl monomers were used for this purpose and they were grafted in twenty different solvents which were selected for their swelling effiency and solvent parameters. The tests were done once with and once without the addition of water. The presence of water causes the polymer uptake to increase considerably. Formic acid/methanol and methanol were found to be the most suitable solvent systems, as they have the highest hydrogen-bond interaction effiency. The moisture uptake of wool depends on the hydrophily and hydrophoby of the grafted polymers. The single-fibre tests serve as a basis for analogous grafting tests on wool fabrics. The permanent- press was improved by graftng with hydrophoric polymers and polymers with a high glass-transition temperature

  14. Photochemical grafting of diazonium salts on metals.

    Science.gov (United States)

    Busson, Mathilde; Berisha, Avni; Combellas, Catherine; Kanoufi, Frédéric; Pinson, Jean

    2011-12-21

    4-Nitrobenzenediazonium may be photochemically grafted onto gold, copper and iron under visible and UV light. Thin nanometre layers are obtained and characterized by IRRAS, electrochemistry and ellipsometry. PMID:22031299

  15. Technique in Cleft Rhinoplasty: The Foundation Graft.

    Science.gov (United States)

    Gassner, Holger G; Schwan, Franziska; Haubner, Frank; Suárez, Gustavo A; Vielsmeier, Veronika

    2016-04-01

    Secondary cleft rhinoplasty represents a particular surgical challenge. The authors have identified the deficit in skeletal projection of the cleft-sided piriform rim as an important contributor to the pathology. A graft is described to augment the piriform crest on the cleft side. This foundation graft is suture fixated to the piriform crest after complete release of all soft tissue attachments to the alar base. The foundation graft is articulated with a long alar strut graft, which allows for powerful projection of the cleft-sided nasal tip. An advancement flap of vestibular skin is described to correct the vestibular stenosis. A transplant of diced cartilage in fascia is added to augment maxillary soft tissue volume. Subjective and objective measures of form and function are presented in a retrospective series of five cases, illustrating the efficacy of the techniques described. PMID:27097143

  16. CT diagnosis of aortic graft infections

    International Nuclear Information System (INIS)

    Two cases of aortic graft infections diagnosed by computed tomography (CT) are presented. CT scans demonstrated a zone of low attenuation in the perigraft area, in one case with a rim enhancement. The diagnoses were verfied by operation. (orig.)

  17. Preparation and biocompatibility of grafted functional β-cyclodextrin copolymers from the surface of PET films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yan, E-mail: yan_jiang_72@126.com [College of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Liang, Yuan; Zhang, Hongwen [College of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Zhang, Weiwei [College of Life Science, Agriculture and Forestry, Qiqihar University, Qiqihar 161006, Heilongjiang (China); Tu, Shanshan [College of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China)

    2014-08-01

    The hydrophobic inert surface of poly(ethylene terephthalate) (PET) film has limited its practical bioapplications, in which case, better biocompatibility should be achieved by surface modification. In this work, the copolymer of functional β-cyclodextrin derivatives and styrene grafted surfaces was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized PET. The structures, composition, properties, and surface morphology of the modified PET films were characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by a thick targeted copolymer layer, and the hydrophobic surface of PET was changed into an amphiphilic surface. The copolymer-grafted surfaces were also shown good biocompatibility on which SGC-7901 A549 and A549/DDP cells readily attached and proliferated, demonstrating that the functional copolymer-grafted PET films could be a promising alternative to biomaterials especially for tissue engineering. - Highlights: • The PET film was grafted by functional β-CD copolymers, which owns amphiphilicity. • The surface of grafted PET film by copolymers enhanced the cell adhesion and growth. • The biocompatible PET film may be used in tissue engineering and cell cultivation.

  18. Comparative study of chemical and biochemical properties of different melon cultivars: standard, hybrid, and grafted melons.

    Science.gov (United States)

    Kolayli, Sevgi; Kara, Meryem; Tezcan, Filiz; Erim, F Bedia; Sahin, Huseyin; Ulusoy, Esra; Aliyazicioglu, Rezzan

    2010-09-01

    Chemical and biochemical properties of standard, hybrid, and grafted melons cultivated under the same agricultural conditions in adjacent fields in the Cumra region of Turkey were investigated and compared based on pH, Brix, antioxidant activity, total phenolics, ascorbic acid, individual phenolics, sugar, and organic acid values. Seventeen different phenolic constituents were quantified by reverse phase high-performance liquid chromatography (RP-HPLC). The highest phenolic acid variability and content were detected in the standard melon. Sugar and organic acid compositions of melon cultivars were tested by capillary electrophoresis, and significant differences in types and contents of individual sugars and organic acids were determined among the cultivars. Standard Cinikiz Cumra melons had the highest ascorbic acid, total phenolics, and total sugar contents. The fructose/glucose ratio increased three times in grafted melon as compared with standard melon. While sugar alcohol mannitol existed in the standard and hybrid cultivars, this constituent disappeared in the grafted types. Citric acid found in the standard cultivar was not detected in the hybrid and grafted types. Consequently, it was concluded that the nutritional value of melons changed by the application of hybridization, grafting, or standard (open pollinated) production methods. The standard melon was found to have the highest score in terms of taste, because of its highest sweetness and sourness. It was also found preferable because of its high antioxidant activity, total phenolic and ascorbic acid contents. PMID:20715772

  19. Preparation and biocompatibility of grafted functional β-cyclodextrin copolymers from the surface of PET films

    International Nuclear Information System (INIS)

    The hydrophobic inert surface of poly(ethylene terephthalate) (PET) film has limited its practical bioapplications, in which case, better biocompatibility should be achieved by surface modification. In this work, the copolymer of functional β-cyclodextrin derivatives and styrene grafted surfaces was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized PET. The structures, composition, properties, and surface morphology of the modified PET films were characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by a thick targeted copolymer layer, and the hydrophobic surface of PET was changed into an amphiphilic surface. The copolymer-grafted surfaces were also shown good biocompatibility on which SGC-7901 A549 and A549/DDP cells readily attached and proliferated, demonstrating that the functional copolymer-grafted PET films could be a promising alternative to biomaterials especially for tissue engineering. - Highlights: • The PET film was grafted by functional β-CD copolymers, which owns amphiphilicity. • The surface of grafted PET film by copolymers enhanced the cell adhesion and growth. • The biocompatible PET film may be used in tissue engineering and cell cultivation

  20. “Over-inlay” block graft and differential morphometry: a novel block graft model to study bone regeneration and host-to-graft interfaces in rats

    Science.gov (United States)

    2016-01-01

    Purpose The aim of this study was to present new a model that allows the study of the bone healing process, with an emphasis on the biological behavior of different graft-to-host interfaces. A standardized “over-inlay” surgical technique combined with a differential histomorphometric analysis is presented in order to optimize the use of critical-size calvarial defects in pre-clinical testing. Methods Critical-size defects were created into the parietal bone of 8 male Wistar rats. Deproteinized bovine bone (DBBM) blocks were inserted into the defects, so that part of the block was included within the calvarial thickness and part exceeded the calvarial height (an “over-inlay” graft). All animals were sacrificed at 1 or 3 months. Histomorphometric and immunohistochemical evaluation was carried out within distinct regions of interest (ROIs): the areas adjacent to the native bone (BA), the periosteal area (PA) and the central area (CA). Results The animals healed without complications. Differential morphometry allowed the examination of the tissue composition within distinct regions: the BA presented consistent amounts of new bone formation (NB), which increased over time (24.53%±1.26% at 1 month; 37.73%±0.39% at 3 months), thus suggesting that this area makes a substantial contribution toward NB. The PA was mainly composed of fibrous tissue (71.16%±8.06% and 78.30%±2.67%, respectively), while the CA showed high amounts of DBBM at both time points (78.30%±2.67% and 74.68%±1.07%, respectively), demonstrating a slow remodeling process. Blood vessels revealed a progressive migration from the interface with native bone toward the central area of the graft. Osterix-positive cells observed at 1 month within the PA suggested that the periosteum was a source of osteoprogenitor elements. Alkaline phosphatase data on matrix deposition confirmed this observation. Conclusions The present model allowed for a standardized investigation of distinct graft

  1. Sensing vascularization of ex-vivo produced oral mucosal equivalent (EVPOME) skin grafts in nude mice using optical spectroscopy

    Science.gov (United States)

    Vishwanath, Karthik; Gurjar, Rajan; Kuo, Shiuhyang; Fasi, Anthony; Kim, Roderick; Riccardi, Suzannah; Feinberg, Stephen E.; Wolf, David E.

    2014-03-01

    Repair of soft tissue defects of the lips as seen in complex maxillofacial injuries, requires pre-vascularized multi-tissue composite grafts. Protocols for fabrication of human ex-vivo produced oral mucosal equivalents (EVPOME) composed of epithelial cells and a dermal equivalent are available to create prelaminated flaps for grafting in patients. However, invivo assessment of neovascularization of the buried prelaminated flaps remains clinically challenging. Here, we use diffuse reflectance spectroscopy (DRS) and diffuse correlation spectroscopy (DCS) to non-invasively quantify longitudinal changes in the vessel density and blood-flow within EVPOME grafts implanted in the backs of SCID mice and subsequently to determine the utility of these optical techniques for assessing vascularization of implanted grafts. 20 animals were implanted with EVPOME grafts (1x1x0.05 cm3) in their backs. DRS and DCS measurements were obtained from each animal both atop the graft site and far away from the graft site, at one week post-implantation, each week, for four consecutive weeks. DRS spectra were analyzed using an inverse Monte Carlo model to extract tissue absorption and scattering coefficients, which were then used to extract blood flow information by fitting the experimental DCS traces. There were clear differences in the mean optical parameters (averaged across all mice) at the graft site vs. the off-site measurements. Both the total hemoglobin concentration (from DRS) and the relative blood flow (from DCS) peaked at week 3 at the graft site and declined to the off-site values by week 4. The optical parameters remained relatively constant throughout 4 weeks for the off-site measurements.

  2. Conduits for Coronary Bypass: Vein Grafts

    OpenAIRE

    Barner, Hendrick B.; Farkas, Emily A.

    2012-01-01

    The saphenous vein has been the principal conduit for coronary bypass grafting from the beginning, circa 1970. This report briefly traces this history and concomitantly presents one surgeons experience and personal views on use of the vein graft. As such it is not exhaustive but meant to be practical with a modest number of references. The focus is that of providing guidance and perspective which may be at variance with that of others and recognizing that there may be many ways to accomplish ...

  3. Biomaterials in Maxillofacial Surgery: Membranes and Grafts

    OpenAIRE

    Rodella, Luigi F.; Favero, Gaia; Labanca, Mauro

    2011-01-01

    Today, significant differences in the use of biomaterials (membranes and grafts) of animal or synthetic origin have yet to be reported. Nevertheless, some evidences suggest that synthetic materials have a lower risk of disease transmission. This review aims to assess the available informations on regenerative bone technique using reasorbable membranes and bone grafts. In particular, biocompatibility, immunological response, tissue reaction, reabsorption time and histological features of mater...

  4. Polypeptide Grafted Hyaluronan: Synthesis and Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun [ORNL; Messman, Jamie M [ORNL; Mays, Jimmy [ORNL; Baskaran, Durairaj [University of Tennessee, Knoxville (UTK)

    2010-01-01

    Poly(L-leucine) grafted hyaluronan (HA-g-PLeu) has been synthesized via a Michael addition reaction between primary amine terminated poly(L-leucine) and acrylate-functionalized HA (TBAHA-acrylate). The precursor hyaluronan was first functionalized with acrylate groups by reaction with acryloyl chloride in the presence of triethylamine in N,N-dimethylformamide. 1H NMR analysis of the resulting product indicated that an increase in the concentration of acryloylchoride with respect to hydroxyl groups on HA has only a moderate effect on functionalization efficiency, f. A precise control of stoichiometry was not achieved, which could be attributed to partial solubility of intermolecular aggregates and the hygroscopic nature of HA. Michael addition at high [PLeu- NH2]/[acrylate]TBAHA ratios gave a molar grafting ratio of only 0.20 with respect to the repeat unit of HA, indicating grafting limitation due to insolubility of the grafted HA-g-PLeu. Soluble HA-g-PLeu graft copolymers were obtained for low grafting ratios (<0.039) with <8.6% by mass of PLeu and were characterized thoroughly using light scattering, 1H NMR, FT-IR, and AFM techniques. Light scattering experiments showed a strong hydrophobic interaction between PLeu chains, resulting in aggregates with segregated nongrafted HA segments. This yields local networks of aggregates, as demonstrated by atomic force microscopy. Circular dichroism spectroscopy showed a -sheet conformation for aggregates of poly(L-leucine).

  5. Local graft irradiation in renal transplant rejection

    International Nuclear Information System (INIS)

    From 1977 to 1988, of 142 renal transplantations, seven recipients (4.9%) received local graft irradiation following rejective reaction refractory to antirejection medical managements. Concurrent with the administration of pulsed high dose methylprednisolone and other antirejection medical managements, the graft was irradiated with a total dose of 6.0 Gy-150 cGy per fraction every other day at the midplane of the graft using two opposing portals of 4MX Linac. The fields were defined by palpation and echography. All patients had improvements in serum creatinine on the 10th day after beginning the irradiation. Four patients with peripheral lymphocytosis during the irradiation combined with pulsed high dose methylprednisolone improved in renal functions. On the other hand, out of 3 patients with lymphcytopenic changes, in two the transplanted graft was removed due to deteriorations, and the other patient is currently suffering from chronic rejection. Local graft irradiation can be useful in maintaining a rejective graft and reversing its functions in some patients whose rejective reaction failed to respond to the antirejection medical managements. (author)

  6. Local graft irradiation in renal transplant rejection

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Masashi; Kataoka, Masaaki; Itoh, Hisao (Ehime Univ., Matsuyama (Japan). School of Medicine)

    1990-04-01

    From 1977 to 1988, of 142 renal transplantations, seven recipients (4.9%) received local graft irradiation following rejective reaction refractory to antirejection medical managements. Concurrent with the administration of pulsed high dose methylprednisolone and other antirejection medical managements, the graft was irradiated with a total dose of 6.0 Gy-150 cGy per fraction every other day at the midplane of the graft using two opposing portals of 4MX Linac. The fields were defined by palpation and echography. All patients had improvements in serum creatinine on the 10th day after beginning the irradiation. Four patients with peripheral lymphocytosis during the irradiation combined with pulsed high dose methylprednisolone improved in renal functions. On the other hand, out of 3 patients with lymphcytopenic changes, in two the transplanted graft was removed due to deteriorations, and the other patient is currently suffering from chronic rejection. Local graft irradiation can be useful in maintaining a rejective graft and reversing its functions in some patients whose rejective reaction failed to respond to the antirejection medical managements. (author).

  7. Graft-copolymerization onto carbon black

    International Nuclear Information System (INIS)

    Radiation-induced graft copolymerization of vinyl monomer onto carbon black was performed. During the γ-ray- and electron beam-induced polymerization (In-source), or the electron beam post-polymerization, the graft-copolymerization behavior was affected by the kinds of both carbon blacks and monomers, i.e. the smaller the size of carbon black particles, the higher the apparent grafted fraction. Homopolymer in the grafted carbon black samples was washed out by the solvent of the polymer, and the extracted polymer seemed to be dimer or trimer of the used monomer. In the case of the post-polymerization with the pre-irradiation doses of 50 Mrad, homopolymer was hardly observed. The polymer sheets of plastics or rubbers with grafted carbon black had an electrical conductivity unalterable considerably by the heating cycles. The particles of grafted carbon black in the sheet might be kept much more at the surface layer within 100 nm depth than at the inner layer. (author)

  8. Adipose-derived regenerative cell (ADRC)-enriched fat grafting: optimal cell concentration and effects on grafted fat characteristics

    OpenAIRE

    Kakudo, Natsuko; Tanaka, Yoshihito; Morimoto, Naoki; Ogawa, Takeshi; Kushida, Satoshi; Hara, Tomoya; Kusumoto, Kenji

    2013-01-01

    Background To overcome the absorption of traditional fat grafting, techniques for adipose-derived regenerative cell (ADRC)-enriched fat grafting are currently being adapted for practical application. The Celution®800/CRS (Cytori Therapeutics, San Diego, CA) has enabled rapid grafting of the patient’s own freshly harvested ADRCs without requiring a culturing step. However, the optimal cell concentration and the effects of ADRCs on the characteristics of grafted fat after free fat grafting rema...

  9. Isotopic scintigraphy in kidney grafting

    International Nuclear Information System (INIS)

    Isotopic explorations of kidney transplants were performed on sixty-six patients. Three scintigraphic techniques were used: labelled ferrous ascorbate scintigraphy, sequential 99m technetium DTPA scintigraphy and the 131I hippuran nephrogram. The aim of this study is to analyse the results obtained under different pathological circumstances affecting the transplant, to discuss the advantages of the techniques and to propose a working procedure. The most reliable and accurate technique is the 131I hippuran nephrogram combined with sequential 99mTc DTPA, by which renal vascularisation may be judged labelled ferrous ascorbate on the other hand is too insensitive. Although the information supplied is mostly contained in the scintigraphic images, the nephrographic curves and the blood radioactivity decay time and rad V/rad R ratio measurements are very helpful in the early diagnosis and differential diagnosis of complications affecting the transplant. The proper use of isotopic scintigraphy in kidney grafting should provide optimum conditions for better survival of the transplant at minimum risk to the patient

  10. The cardiovascular system and the biochemistry of grafts used in heart surgery.

    Science.gov (United States)

    Aydin, Suna; Aydin, Suleyman; Nesimi Eren, Mehmet; Sahin, Ibrahim; Yilmaz, Musa; Kalayci, Mehmet; Gungor, Orhan

    2013-01-01

    Blood is pumped into the cardiac muscle through arteries called the coronary arteries. Over time, the accumulation of cholesterol, coagulation factors, and cells on the walls of these arteries causes the walls to thicken and lose their elasticity, resulting in the development of atherosclerosis. When the blood supply of the heart is diminished by atherosclerosis, it can be restored by bypass surgery, in which atherosclerosis-free vein and/or artery grafts taken from another area of the body are used to replace the atherosclerotic vessels. These biological grafts used in surgery differ in biochemical composition and long-term patency. Although the great saphenous vein (GSV) has been the most popular graft material in revascularization for years, it has recently been superseded by the internal mammarian artery (IMA), which has a lower incidence of recurrence of atherosclerosis. The aim of the present review is briefly to address the structure of the cardiovascular system and blood vessels, and then, in the light recent data, to present the biochemical compositions and individual advantages of the graft materials used to restore an impaired blood supply to the heart. PMID:24324924

  11. Physical properties of agave cellulose graft polymethyl methacrylate

    Science.gov (United States)

    Rosli, Noor Afizah; Ahmad, Ishak; Abdullah, Ibrahim; Anuar, Farah Hannan

    2013-11-01

    The grafting polymerization of methyl methacrylate and Agave cellulose was prepared and their structural analysis and morphology were investigated. The grafting reaction was carried out in an aqueous medium using ceric ammonium nitrate as an initiator. The structural analysis of the graft copolymers was carried out by Fourier transform infrared and X-ray diffraction. The graft copolymers were also characterized by field emission scanning electron microscopy (FESEM). An additional peak at 1732 cm-1 which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted Agave cellulose, respectively. Another evidence of grafting showed in the FESEM observation, where the surface of the grafted cellulose was found to be roughed than the raw one.

  12. Physical properties of agave cellulose graft polymethyl methacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Rosli, Noor Afizah; Ahmad, Ishak; Abdullah, Ibrahim; Anuar, Farah Hannan [Polymer Research Centre (PORCE), School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor (Malaysia)

    2013-11-27

    The grafting polymerization of methyl methacrylate and Agave cellulose was prepared and their structural analysis and morphology were investigated. The grafting reaction was carried out in an aqueous medium using ceric ammonium nitrate as an initiator. The structural analysis of the graft copolymers was carried out by Fourier transform infrared and X-ray diffraction. The graft copolymers were also characterized by field emission scanning electron microscopy (FESEM). An additional peak at 1732 cm{sup −1} which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted Agave cellulose, respectively. Another evidence of grafting showed in the FESEM observation, where the surface of the grafted cellulose was found to be roughed than the raw one.

  13. Radiation grafting of styrene and acrylonitrile to cellulose and polyethylene

    Science.gov (United States)

    Hassanpour, S.

    1999-06-01

    Radiation induced graft polymerization is one of the best methods for obtaining material with new properties. In this work, radiation grafting of styrene, mixture of styrene and acrylonitrile to cellulose and polyethylene in the presence of methanol as a solvent by mutual method is discussed. At a low dose rate, high grafting yields were obtained from the two systems used, due to lesser termination of free radicals with the polymer growing radicals and recombination of primary radicals, resulting in a longer chain length of the grafted copolymer. In the system of styrene and acrylonitrile, comonomer technique was used and the styrene controlled the homopolymer formation during graft polymerization. Water uptake of cellulose decreased by increasing the grafting yields. Grafted cellulose can be molded to some extent and in a high percent of grafting, a new transparent material was obtained. By radiation grafting of styrene-acrylonitrile to low density polyethylene a high degree of crosslinking was observed.

  14. Physical properties of agave cellulose graft polymethyl methacrylate

    International Nuclear Information System (INIS)

    The grafting polymerization of methyl methacrylate and Agave cellulose was prepared and their structural analysis and morphology were investigated. The grafting reaction was carried out in an aqueous medium using ceric ammonium nitrate as an initiator. The structural analysis of the graft copolymers was carried out by Fourier transform infrared and X-ray diffraction. The graft copolymers were also characterized by field emission scanning electron microscopy (FESEM). An additional peak at 1732 cm−1 which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted Agave cellulose, respectively. Another evidence of grafting showed in the FESEM observation, where the surface of the grafted cellulose was found to be roughed than the raw one

  15. Study on polyethylene films grafted with vinyl acetate and ethyl methacrylate by radiation grafting

    International Nuclear Information System (INIS)

    Low density polyethylene (LDPE) films were grafted with a vinyl acetate (VAc) and ethyl methacrylate (EMA) commoner mixture by radiation using a 60Co gamma source. IR spectra and x-ray diffraction (XRD) for the original PE matrix and for the graft copolymers were studied. Electrical conductivity and thermal properties of the prepared grafted materials were also measured. XRD results showed that poly(vinyl acetate/ethyl methacrylate) P(VAc/EMA) graft chains cause a decrease in the crystallinity of the PE polymer substrate. The changes in thermal parameters such as melting (Tm) and crystallization (Tc) temperatures and heats of melting (ΔHm) and crystallization (ΔHc) of the graft copolymers were followed by differential scanning calorimetry (DSC) and for thermal stability by TGA. These thermal parameters of PE were influenced by grafting, with VAc and EMA and depended on the percent grafting, which reflected the change in crystallinity due to formation of branches via the grafted chains. (author)

  16. Grafting Seedless Watermelons, How and Why? Will Grafting Help With Disease Control?

    Science.gov (United States)

    In recent years, the practice of grafting seedless watermelons (triploids) onto rootstocks belonging to other Cucurbitaceae genera has gained importance in the United States. Grafting vegetable crops, especially cucurbit’s, is very common in Europe and Asia. In these regions, the practice of crop ...

  17. Complications in skin grafts when continuing antithrombotic therapy prior to cutaneous surgery requiring skin grafting

    DEFF Research Database (Denmark)

    Jarjis, Reem Dina; Jørgensen, Lone; Finnerup, Kenneth;

    2015-01-01

    Abstract The risk of postoperative bleeding and wound healing complications in skin grafts among anticoagulated patients undergoing cutaneous surgery has not been firmly established. The objective was to examine the literature and assess the risk of postoperative bleeding or wound healing...... complications in skin grafts among anticoagulated patients, compared with patients who discontinue or patients who are not receiving antithrombotic therapy prior to cutaneous surgery requiring skin grafting. A systematic review examining the effect of antithrombotic therapy on cutaneous surgery was performed...... terms of hemostasis by the surgeon and good pressure dressings. Care should be taken when operating on anticoagulated patients undergoing cutaneous surgery requiring skin grafting. However, graft failure is rare and, given the risk of thrombotic events, the reviewed studies recommend continuing all...

  18. Development of Highly Efficient Grafting Technique and Synthesis of Natural Polymer-Based Graft Adsorbent

    International Nuclear Information System (INIS)

    In the framework of the CRP, Japan has focused on the development of fibrous adsorbents for removal of toxic metal ions and recovery of significant metal ions from industrial wastewater and streaming water. Graft polymerization was carried out by using gamma irradiation facility and electron beam accelerator. Emulsion grafting is a novel topic for synthesis of metal ion adsorbents which are prepared from fibrous trunk polymers such as polyethylene fibre and biodegradable nonwoven fabrics. The emulsion grafting, where monomer micelles are dispersed in water in the presence of surfactant, is a highly efficient and economic grafting technique as compared to general organic solvent system. The resultant cotton-based adsorbent has high adsorption efficiency and high adsorption capacity for Hg, besides, it is biodegradable. Polylactic acid can also be used as a trunk material for the grafting. (author)

  19. Effect of acid additives on grafting efficiency and water absorption of hydrolyzed cassava starch grafted polymers

    International Nuclear Information System (INIS)

    Gelatinized cassava starch was radiation graft copolymerized with acrylamide, acrylic acid or their mixture in the presence of sulphuric acid or maleic acid. Various acid concentrations were used from 0.001 to 0.1 M of sulphuric acid while the maleic acid concentrations were varied from 1 to 3% (by weight). The optimum total dose and dose rate were investigated. The saponification temperature and time had the marked effects on grafting characteristics and water absorption capacity. We found that the effect of maleic acid addition gave a profound effect on water absorption. The CHNS/O analyses indicated significant changes in the nitrogen content in the hydrolyzed starch grafted polyacrylamide with 2% maleic acid. The article explains the possible causes for the enhancement influence of mineral acid and maleic acid on grafting behavior and water absorption of the saponified cassava starch grafted polyacrylamide super absorbent polymer. (author)

  20. Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states

    Science.gov (United States)

    Wåhlander, Martin; Nilsson, Fritjof; Carlmark, Anna; Gedde, Ulf W.; Edmondson, Steve; Malmström, Eva

    2016-08-01

    We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been immobilised on anionic GO and subsequently grafted with hydrophobic polymer grafts. Dense grafts of PBA, PBMA and PMMA with a wide range of average graft lengths (MW: 1-440 kDa) were polymerised by surface-initiated controlled radical precipitation polymerisation from the statistical MI. The surface modification is designed similarly to bimodal graft systems, where the cationic MI generates nanoparticle repulsion, similar to dense short grafts, while the long grafts offer miscibility in non-polar environments and cohesion. The state-of-the-art dispersions of grafted GO were in the isotropic state. Transparent and translucent matrix-free GO-composites could be melt-processed directly using only grafted GO. After processing, birefringence due to nematic alignment of grafted GO was observed as a single giant Maltese cross, 3.4 cm across. Permeability models for composites containing aligned 2D-fillers were developed, which were compared with the experimental oxygen permeability data and found to be consistent with isotropic or nematic states. The storage modulus of the matrix-free GO-composites increased with GO content (50% increase at 0.67 wt%), while the significant increases in the thermal stability (up to 130 °C) and the glass transition temperature (up to 17 °C) were dependent on graft length. The tuneable matrix-free GO-composites with rapid thermo-responsive shape-memory effects are promising candidates for a vast range of applications, especially selective membranes and sensors.We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been

  1. Plasma-mediated grafting of poly(ethylene glycol) on polyamide and polyester surfaces and evaluation of antifouling ability of modified substrates.

    Science.gov (United States)

    Dong, Baiyan; Jiang, Hongquan; Manolache, Sorin; Wong, Amy C Lee; Denes, Ferencz S

    2007-06-19

    A simple cold plasma technique was developed to functionalize the surfaces of polyamide (PA) and polyester (PET) for the grafting of polyethylene glycol (PEG) with the aim of reducing biofilm formation. The surfaces of PA and PET were treated with silicon tetrachloride (SiCl4) plasma, and PEG was grafted onto plasma-functionalized substrates (PA-PEG, PET-PEG). Different molecular weights of PEG and grafting times were tested to obtain optimal surface coverage by PEG as monitored by electron spectroscopy for chemical analysis (ESCA). The presence of a predominant C-O peak on the PEG-modified substrates indicated that the grafting was successful. Data from hydroxyl group derivatization and water contact angle measurement also indicated the presence of PEG after grafting. The PEG-grafted PA and PET under optimal conditions had similar chemical composition and hydrophilicity; however, different morphology changes were observed after grafting. Both PA-PEG and PET-PEG surfaces developed under optimal plasma conditions showed about 96% reduction in biofilm formation by Listeria monocytogenes compared with that of the corresponding unmodified substrates. This plasma functionalization method provided an efficient way to graft PEG onto PA and PET surfaces. Because of the high reactivity of Si-Cl species, this method could potentially be applied to other polymeric materials. PMID:17500575

  2. Adolescent External Iliac Artery Trauma: Recurrent Aneurysmal Dilatation of an Iliofemoral Saphenous Vein Graft Treated by Stent-Grafting

    International Nuclear Information System (INIS)

    An adolescent male sustained a severe penetrating injury to the external iliac artery. Emergency surgical revascularization was with a reversed long saphenous vein interposition graft. The primary graft and the subsequent revision graft both became aneurysmal. The second graft aneurysm was successfully excluded by endovascular stent-grafts with medium-term primary patency. A venous graft was used initially rather than a synthetic graft to reduce the risk of infection and the potential problems from future growth. Aneurysmal dilatation of venous grafts in children and adolescents is a rare but recognized complication. To the best of our knowledge, exclusion of these aneurysms with stent-grafts has not been previously reported in the adolescent population.

  3. Grafting polymerization of styrene onto preirradiated polypropylene fabric

    International Nuclear Information System (INIS)

    Grafting copolymerization of styrene onto polypropylene fabric has been studied by using a gamma ray preirradiation technique. The polypropylene fabric samples were irradiated in an environment of air and nitrogen gas. The effects of the absorbed dose, styrene concentration in methanol, reaction temperature and reaction time on the degree of grafting were determined. The effects of a polyfunctional monomer and sulphuric acid on the grafting yield were also examined. The samples irradiated in nitrogen gas gave a much higher degree of grafting than those in air. The addition of sulfuric acid and polyfunctional monomer in the grafting solution enhanced greatly the grafting yield

  4. Grafting copolymerization of acrylamides onto preirradiated PP films

    Science.gov (United States)

    Chen, Jie; Nho, Young Chang; Kwon, Oh Hyun; Hoffman, Allan S.

    1999-06-01

    Acrylamide (AAm), N,N-Dimethylacrylamide (DMAAm) and N-(3-Dimethylaminopropyl) methacrylamide (DMAPMAAm) were grafted onto polypropylene (PP) films by preirradiation grafting respectively. The effect of irradiation dose, solvent systems and reaction time on the degree of grafting were determined. The grafted sample films were verified by Fourier Transform Infrared (FTIR) spectroscopy in the attenuated total reflectance mode (ATR) and the determination of water contact angle. The blood compatibility of the grafted PP films were evaluated by the determination of platelet adsorption and thrombus. The blood compatibility of grafted PP films seems better than that of original PP films.

  5. Dextran grafting on PTFE surface for cardiovascular applications.

    Science.gov (United States)

    Michel, Eléonore C; Montaño-Machado, Vanessa; Chevallier, Pascale; Labbé-Barrère, Amélie; Letourneur, Didier; Mantovani, Diego

    2014-01-01

    The modification of biomaterial surfaces with biomolecules influences the biological response. In this work, caboxymethyldextrans (CMD) with different degrees of substitution have been grafted to surfaces by introduction of amino moieties directly onto the substrate surface. Polytetrafluoroethylene was selected as a model substrate for biomaterial as it is already largely used for cardiovascular clinical applications. Firstly, CMD polymers were characterized by FTIR, (1)H-NMR, and conductimetric titration. Then, the coatings have been analyzed by XPS to confirm the grafting and determine the composition. Once characterized, biological performances of CMD coatings were investigated. The hemocompatibility was ascertained using the free hemoglobin method. The effects on endothelial and smooth muscle cell adhesion were also studied. Results indicated that CMD at a 0.2 substitution degree, significantly influenced the biological property of PTFE by exhibiting non-thrombogenic properties as well as enhancing endothelial cell adhesion along with limiting smooth muscle cell adhesion. This work suggested the creation of versatile pro-active biomaterials suitable for different biomedical applications. PMID:25482414

  6. Polymer grafting modification of the surface of nano silicon dioxide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the composite modification technology of the surface of nano silicon dioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on the surface of nano silicon dioxide. The modification mechanism and the bonding status on the surface of nano silicon dioxide after modification were suggested via the results of the infrared spectrum, transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formed by hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxide to form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto the surface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer through free radical polymerization between the double bonds on the surface of nano silicon dioxide and styrene under the action of initiating agent. The dispersibility of nano silicon dioxide and the controllability of surface modification of nano silicon dioxide can be greatly improved by the modification process.

  7. Development of deodorizing materials by radiation graft polymerization

    International Nuclear Information System (INIS)

    With the development of society, the countermeasures for service water and sewerage in large cities and the environment preservation in industrial districts become difficult as their scale becomes larger. There are many unsolved problems, for example photochemical smog due to harmful gases, exhaust gas from automobiles, and smell of toilets and home waste water. The deodorizing materials used so far are mainly inorganic substances, and their ability of adsorbing harmful gases is very low. Besides, those are mostly granular, and limited in the formability. Therefore, it is expected to develop the fibrous adsorbent which has large adsorbing surface area and is easy to make filters. The chemical structures of the compounds having smell are shown. Eight legal bad smell substances which exert large influence to environment even in very small amount are designated. In this paper, the method of introducing functional radicals into existing fiber materials by the application of radiation graft polymerization process and the test of removing smelling compositions by using the obtained resin are reported. The experimental method, and the results of radiation graft polymerization, the adsorption of basic gases and acid gases, and gas flow test are described. (K.I.)

  8. Corneal Graft Rejection: Incidence and Risk Factors

    Directory of Open Access Journals (Sweden)

    Alireza Baradaran-Rafii

    2008-12-01

    Full Text Available

    PURPOSE: To determine the incidence and risk factors of late corneal graft rejection after penetrating keratoplasty (PKP. METHODS: Records of all patients who had undergone PKP from 2002 to 2004 without immunosuppressive therapy other than systemic steroids and with at least one year of follow up were reviewed. The role of possible risk factors such as demographic factors, other host factors, donor factors, indications for PKP as well as type of rejection were evaluated. RESULTS: During the study period, 295 PKPs were performed on 286 patients (176 male, 110 female. Mean age at the time of keratoplasty was 38±20 (range, 40 days to 90 years and mean follow up period was 20±10 (range 12-43 months. Graft rejection occurred in 94 eyes (31.8% at an average of 7.3±6 months (range, 20 days to 39 months after PKP. The most common type of rejection was endothelial (20.7%. Corneal vascularization, regrafting, anterior synechiae, irritating sutures, active inflammation, additional anterior segment procedures, history of trauma, uncontrolled glaucoma, prior graft rejection, recurrence of herpetic infection and eccentric grafting increased the rate of rejection. Patient age, donor size and bilateral transplantation had no significant influence on graft rejection. CONCLUSION: Significant risk factors for corneal graft rejection include

  9. Controlled Grafting of Poly(methyl methacrylate) Brushes on Poly(vinylidene fluoride) Powders by Surface-initiated Atom Transfer Radical Polymerization

    Institute of Scientific and Technical Information of China (English)

    TANG Zhaoqi; LI Wei; LIU Lanqin; HUANG Lei; ZHOU Jin; YU Haiyin

    2009-01-01

    Controlled grafting of well-defined polymer brushes of methyl methacrylate (MMA) on the poly(vinylidene fluoride) (PVDF) powders was carded out by the surface-initiated atom transfer radical polymerization (ATRP). The ATRP initiator was anchored on the PVDF surface by alkaline treatment, followed by UV-induced bromination; then methyl methacrylate (MMA) was grafted onto the brominated PVDF by the ATRP technique. The chemical composition changes of PVDF were characterized by Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS results clearly indicated the successful graft of poly(methyl methacrylate) onto the PVDF surface.

  10. Aortic reconstruction with bovine pericardial grafts

    Directory of Open Access Journals (Sweden)

    Silveira Lindemberg Mota

    2003-01-01

    Full Text Available INTRODUCTION: Glutaraldehyde-treated crimped bovine pericardial grafts are currently used in aortic graft surgery. These conduits have become good options for these operations, available in different sizes and shapes and at a low cost. OBJECTIVE:To evaluate the results obtained with bovine pericardial grafts for aortic reconstruction, specially concerning late complications. METHOD: Between January 1995 and January 2002, 57 patients underwent different types of aortic reconstruction operations using bovine pericardial grafts. A total of 29 (50.8% were operated on an urgent basis (mostly acute Stanford A dissection and 28 electively. Thoracotomy was performed in three patients for descending aortic replacement (two patients and aortoplasty with a patch in one. All remaining 54 underwent sternotomy, cardiopulmonary bypass and aortic resection. Deep hypothermia and total circulatory arrest was used in acute dissections and arch operations. RESULTS: Hospital mortality was 17.5%. Follow-up was 24.09 months (18.5 to 29.8 months confidence interval and complication-free actuarial survival curve was 92.3% (standard deviation ± 10.6. Two patients lately developed thoracoabdominal aneurysms following previous DeBakey II dissection and one died from endocarditis. One "patch" aortoplasty patient developed local descending aortic pseudoaneurysm 42 months after surgery. All other patients are asymptomatic and currently clinically evaluated with echocardiography and CT scans, showing no complications. CONCLUSION: Use of bovine pericardial grafts in aortic reconstruction surgery is adequate and safe, with few complications related to the conduits.

  11. Radiolytic preparation and characterization of hydrophilic poly(acrylonitrile-co-vinylsulfonate)-grafted porous poly(tetrafluoroethylene) substrates

    Science.gov (United States)

    Park, Byeong-Hee; Sohn, Joon-Yong; Shin, Junhwa

    2016-01-01

    In this study, a hydrophilic copolymer of acrylonitrile (AN) and sodium vinylsulfonate (SVS) was grafted into a highly hydrophobic porous poly(tetrafluoroethylene) (PTFE) substrate using a gamma-ray irradiation method and the grafted substrate was used as a substrate for impregnating a hydrophilic ionomer, Nafion. The results of FT-IR and TGA analysis of the prepared substrate showed that the SVS/AN monomers were successfully grafted into the porous PTFE film. The results of degree of grafting, elemental analyzer, and contact angle analysis showed that the hydrophilicity of the prepared PTFE-g-P(AN-co-VS) substrate was increased with an increase in the amount of SVS/AN graft copolymers. Also, the results of FE-SEM and Gurley number measurement showed that the pores in the substrate were reduced as the amount of SVS/AN copolymers grafted into the substrate increased. The prepared porous PTFE-g-P(AN-co-VS) substrate at an irradiation dose of 70 kGy was found to impregnate Nafion ionomer effectively compared to the original porous PTFE substrate. These results suggest that the prepared PTFE-g-P(AN-co-VS) substrate can be effectively used for the impregnation of polymer electrolyte (Nafion) to prepare a reinforced composite membrane.

  12. Monoblock Expanded Full-thickness Graft for Resurfacing of the Burned Face in Young Patients.

    Science.gov (United States)

    Allam, A M; El Khalek, A E A; Mustafa, W; Zayed, E

    2007-12-31

    It has been emphasized by many authors that to obtain better aesthetic results in a burned facial area to be resurfaced - if it extends into more than one aesthetic territory - the units involved should be combined into a single large composite unit allowing the largest possible skin graft to be used. Unfortunately, the donor site for full-thickness grafts is limited in young patients and hence tissue expansion is used. A monoblock expanded full-thickness skin graft for facial resurfacing after post-burn sequelae excision was used in 12 young patients after expansion of the superolateral aspect of the buttock. Females made up the majority of the patients (75%) and the ages ranged between 8 and 18 yr. The operating time was 3-3.5 hours, in two sessions. Post-operatively, we recorded partial graft necrosis in two cases (16.7%) and infection in one (8.3%), and some minor donor-site-related complications were reported, such as haematoma in one patient (8.3%), wound infection in one patient (8.3%), and wide scarring in two patients (16.7%). At follow-up, eight of the patients (66.7%) were satisfied with their new facial look as the mask effect of facial scarring had been overcome. With monoblock expanded full-thickness graft we were able to resurface the face in nine cases (75%). A second complementary procedure to reconstruct the eyebrows or reshape the nose was required in two cases (16.7%). We concluded that the monoblock expanded full-thickness graft was a suitable solution for limitation of the donor site in young patients, as the resulting wound could be closed primarily with a scar that could be concealed by the underwear, with lim. PMID:21991093

  13. Proteomics analysis of compatibility and incompatibility in grafted cucumber seedlings.

    Science.gov (United States)

    Xu, Qing; Guo, Shi-Rong; Li, Lin; An, Ya-Hong; Shu, Sheng; Sun, Jin

    2016-08-01

    Graft compatibility between rootstock and scion is the most important factor influencing the survival of grafted plants. In this study, we used two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) to investigate differences in leaf proteomes of graft-compatible and graft-incompatible cucumber (Cucumis sativus L.)/pumpkin (Cucurbita L.) combinations. Cucumber seedlings were used as the scions and two pumpkin cultivars with strongly contrasting grafting compatibilities were used as the rootstocks. Non-grafted and self-grafted cucumber seedlings served as control groups. An average of approximately 500 detectable spots were observed on each 2-DE gel. A total of 50 proteins were differentially expressed in response to self-grafting, compatible-rootstock grafting, and incompatible-rootstock grafting and were all successfully identified by MALDI-TOF/TOF MS. The regulation of Calvin cycle, photosynthetic apparatus, glycolytic pathway, energy metabolism, protein biosynthesis and degradation, and reactive oxygen metabolism will probably contribute to intensify the biomass and photosynthetic capacity in graft-compatible combinations. The improved physiological and growth characteristics of compatible-rootstock grafting plants are the result of the higher expressions of proteins involved in photosynthesis, carbohydrate and energy metabolism, and protein metabolism. At the same time, the compatible-rootstock grafting regulation of stress defense, amino acid metabolism, and other metabolic functions also plays important roles in improvement of plant growth. PMID:27070289

  14. Oversized vein grafts develop advanced atherosclerosis in hypercholesterolemic minipigs

    Directory of Open Access Journals (Sweden)

    Thim Troels

    2012-03-01

    Full Text Available Abstract Background Accelerated atherosclerosis is the main cause of late aortocoronary vein graft failure. We aimed to develop a large animal model for the study of pathogenesis and treatment of vein graft atherosclerosis. Methods An autologous reversed jugular vein graft was inserted end-to-end into the transected common carotid artery of ten hypercholesteroemic minipigs. The vein grafts were investigated 12-14 weeks later with ultrasound and angiograpy in vivo and microscopy post mortem. Results One minipig died during follow up (patent vein graft at autopsy, and one vein graft thrombosed early. In the remaining eight patent vein grafts, the mean (standard deviation intima-media thickness was 712 μm (276 μm versus 204 μm (74 μm in the contralateral control internal jugular veins (P diameter of artery. No plaques were found in four non-oversized vein grafts (P Conclusions Our model of jugular vein graft in the common carotid artery of hypercholesterolemic minipigs displayed the components of human vein graft disease, i.e. thrombosis, intimal hyperplasia, and atherosclerosis. Advanced atherosclerosis, the main cause of late failure of human aortocoronary vein grafts was only seen in oversized grafts. This finding suggests that oversized vein grafts may have detrimental effects on patient outcome.

  15. Protected Graft Copolymer (PGC) in Imaging and Therapy: A Platform for the Delivery of Covalently and Non-Covalently Bound Drugs

    OpenAIRE

    Bogdanov Jr, Alexei A.; Mazzanti, Mary; Castillo, Gerardo; Bolotin, Elijah

    2012-01-01

    Initially developed in 1992 as an MR imaging agent, the family of protected graft copolymers (PGC) is based on a conjugate of polylysine backbone to which methoxypoly(ethylene glycol) (MPEG) chains are covalently linked in a random fasion via N-ε-amino groups. While PGC is relatively simple in terms of its chemcial composition and structure, it has proved to be a versatile platform for in vivo drug delivery. The advantages of poly amino acid backbone grafting include multiple available linkin...

  16. Protected Graft Copolymer (PGC) in Imaging and Therapy: A Platform for the Delivery of Covalently and Non-Covalently Bound Drugs

    OpenAIRE

    Alexei A. Bogdanov Jr, Mary Mazzanti, Gerardo Castillo, Elijah Bolotin

    2012-01-01

    Initially developed in 1992 as an MR imaging agent, the family of protected graft copolymers (PGC) is based on a conjugate of polylysine backbone to which methoxypoly(ethylene glycol) (MPEG) chains are covalently linked in a random fasion via N-ε-amino groups. While PGC is relatively simple in terms of its chemcial composition and structure, it has proved to be a versatile platform for in vivo drug delivery. The advantages of poly amino acid backbone grafting include multiple available l...

  17. Within Patient Radiological Comparative Analysis of the Performance of Two Bone Graft Extenders Utilized in Posterolateral Lumbar Fusion: A Retrospective Case Series

    OpenAIRE

    Stewart, Geoffrey; Gage, Gary B.; Neidert, Gary; Adkisson, Huston Davis

    2016-01-01

    Two bone graft extenders differing in chemical composition were implanted contralaterally in 27 consecutive patients undergoing instrumented posterolateral lumbar fusion as standard-of-care. Bone marrow aspirate and autogenous bone graft were equally combined either with β-tricalcium phosphate (β-TCP) or a hybrid biomaterial [containing hyaluronic acid (HyA) but lacking a calcium salt] and implanted between the transverse processes. Fusion status on each side of the vertebrae was retrospectiv...

  18. Evaluation of bone response to synthetic bone grafting material treated with argon-based atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Bone graft materials are utilized to stimulate healing of bone defects or enhance osseointegration of implants. In order to augment these capabilities, various surface modification techniques, including atmospheric pressure plasma (APP) surface treatment, have been developed. This in vivo study sought to assess the effect of APP surface treatment on degradation and osseointegration of Synthograft™, a beta-tricalcium phosphate (β-TCP) synthetic bone graft. The experimental (APP-treated) grafts were subjected to APP treatment with argon for a period of 60 s. Physicochemical characterization was performed by environmental scanning electron microscopy, surface energy (SE), and x-ray photoelectron spectroscopy analyses both before and after APP treatment. Two APP-treated and two untreated grafts were surgically implanted into four critical-size calvarial defects in each of ten New Zealand white rabbits. The defect samples were explanted after four weeks, underwent histological analysis, and the percentages of bone, soft tissue, and remaining graft material were quantified by image thresholding. Material characterization showed no differences in particle surface morphology and that the APP-treated group presented significantly higher SE along with higher amounts of the base material chemical elements on it surface. Review of defect composition showed that APP treatment did not increase bone formation or reduce the amount of soft tissue filling the defect when compared to untreated material. Histologic cross-sections demonstrated osteoblastic cell lines, osteoid deposition, and neovascularization in both groups. Ultimately, argon-based APP treatment did not enhance the osseointegration or degradation of the β-TCP graft. Future investigations should evaluate the utility of gases other than argon to enhance osseointegration through APP treatment. - Highlights: • Degradation/osseointegration of bone graft treated with argon-based APP is studied. • APP treatment did

  19. Surface reconstruction by a "grafting through" approach: polyacrylamide grafted onto chitosan film.

    Science.gov (United States)

    Chu, Elza; Sidorenko, Alexander

    2013-10-01

    Grafted polymers and polymer brushes in particular have attracted significant attention in the last 2 decades as a way to alter and control interfacial properties. In the case of polymer brushes on solid substrates, a high grafting density of polymer chains results in stretching of the polymer coils normal to the substrate surface due to the effect of excluded volume. In this study, polyacrylamide is grafted to the surface of relatively soft thin films of chitosan. The "grafting through" approach is used by introducing double C═C bonds to amino groups of chitosan. The acquired kinetic data of grafting along with AFM and ellipsometry characterization suggest that the chitosan substrate undergoes surface reconstruction during the grafting of PAAm and simultaneously induces PAAm growth inside the soft substrate. As a result, much higher amounts of grafted polymer are achieved in comparison to traditional hard substrates like silicon or glass. Additionally, selective plasma etching of PAAm reveals filament-like structures oriented normal to the surface. PMID:24024703

  20. A method for radiation grafting of polyolefins

    International Nuclear Information System (INIS)

    The procedure of radiation grafting of polyolefins in the swelled state with graft monomers from the class of methacrylic and acrylic acids and their reactive derivatives, was modified so as to obtain copolymers with ample short (often single-membered) side chains of the acids. To achieve this, the grafting was conducted in the presence of efficient radical polymerization inhibitors from the class of polyvalent phenols such as hydroquinone or tert-butylpyrocatechol, and of efficient chain carriers from the class of halogenated aliphatic hydrocarbons and mercapto compounds such as CCl4, CHCl3, CHBr3, thioacetic acid or ethyl bromide. The polymers so obtained are well suited to the manufacture of dialysis and electrodialysis membranes and hollow fibres. (P.A.)

  1. Meshed split skin graft for extensive vitiligo

    Directory of Open Access Journals (Sweden)

    Srinivas C

    2004-05-01

    Full Text Available A 30 year old female presented with generalized stable vitiligo involving large areas of the body. Since large areas were to be treated it was decided to do meshed split skin graft. A phototoxic blister over recipient site was induced by applying 8 MOP solution followed by exposure to UVA. The split skin graft was harvested from donor area by Padgett dermatome which was meshed by an ampligreffe to increase the size of the graft by 4 times. Significant pigmentation of the depigmented skin was seen after 5 months. This procedure helps to cover large recipient areas, when pigmented donor skin is limited with minimal risk of scarring. Phototoxic blister enables easy separation of epidermis thus saving time required for dermabrasion from recipient site.

  2. Volumetric changes of the graft after maxillary sinus floor augmentation with Bio-Oss and autogenous bone in different ratios

    DEFF Research Database (Denmark)

    Jensen, Thomas; Schou, Søren; Svendsen, Patricia Anne;

    2012-01-01

    composition was selected at random and placed concomitant with implant placement. Computed tomographies of the maxillary sinuses were obtained preoperatively, immediately postoperatively, and at euthanasia after 12 weeks. The volumetric changes of the graft were estimated using the Cavalieri principle and...

  3. The polyvinylpyrrolidone graft copolymers and soft contact lenses on their basis

    Directory of Open Access Journals (Sweden)

    Oleg Suberlyak

    2014-12-01

    Full Text Available The graft polymerization of 2-hydroxyethyl methacrylate in presence of polyvinylpyrrolidone, which occurs through a stage of complex formation between the reactants, was investigated. The basic performance properties of hydrogel copolymers depending on their composition were investigated. A hydrogel polymeric material “Akrylan-LPI” for soft contact lenses was developed. Clinical testing confirmed the effectiveness of using of such lenses for vision correction as well as for eye injuries and burns treating.

  4. Cellulose-based graft copolymers with controlled architecture prepared in a homogeneous phase

    Czech Academy of Sciences Publication Activity Database

    Raus, Vladimír; Štěpánek, M.; Uchman, M.; Šlouf, Miroslav; Látalová, Petra; Čadová, Eva; Netopilík, Miloš; Kříž, Jaroslav; Dybal, Jiří; Vlček, Petr

    2011-01-01

    Roč. 49, č. 20 (2011), s. 4353-4367. ISSN 0887-624X R&D Projects: GA ČR GA106/09/1348; GA ČR GAP208/10/0353 Institutional research plan: CEZ:AV0Z40500505 Keywords : atom transfer radical polymer ization (ATRP) * cellulose * graft copolymers Subject RIV: JI - Composite Materials Impact factor: 3.919, year: 2011

  5. Autologous Fat Grafting for Whole Breast Reconstruction

    Directory of Open Access Journals (Sweden)

    Benjamin H. L. Howes, MBBS

    2014-03-01

    Full Text Available Summary: This is the first reported case of a patient who had a single-stage large-volume breast reconstruction with autologous fat grafting, following rotation flap approach (RoFA mastectomy. The purpose of this case study was to evaluate the viability of reconstruction of the breast by autologous fat grafting alone, in the context of RoFA mastectomy. The hypothesis was that there would be minimal interval loss of autologous fat on the whole breast reconstruction side. Right RoFA mastectomy was used for resection of an invasive primary breast cancer and resulted in the right breast skin envelope. Eleven months later, the patient underwent grafting of 400 ml of autologous fat into the skin envelope and underlying pectoralis major muscle. Outcome was assessed by using a validated 3D laser scan technique for quantitative breast volume measurement. Other outcome measures included the BREAST-Q questionnaire and 2D clinical photography. At 12-month follow-up, the patient was observed to have maintenance of volume of the reconstructed breast. Her BREAST-Q scores were markedly improved compared with before fat grafting, and there was observable improvement in shape, contour, and symmetry on 2D clinical photography. The 2 new techniques, RoFA mastectomy and large-volume single-stage autologous fat grafting, were used in combination to achieve a satisfactory postmastectomy breast reconstruction. Novel tools for measurement of outcome were the 3D whole-body laser scanner and BREAST-Q questionnaire. This case demonstrates the potential for the use of fat grafting for reconstruction. Outcomes in a larger patient populations are needed to confirm these findings.

  6. Modification of microcystalline cellulose by gamma radiation-induced grafting

    International Nuclear Information System (INIS)

    Modified crystalline cellulose (MCC) was prepared through gamma radiation-induced graft polymerization of glycidyl methacrylate (GMA). Simultaneous grafting was employed wherein MCC with GMA in methanol was irradiated with gamma radiation in nitrogen atmosphere. The effects of different experimental factors such as monomer concentration, type of solvent and absorbed dose on the degree of grafting, Dg, were studied. The amount of grafted GMA, expressed as Dg, was determined gravimetrically. Information from grafted samples subjected to Fourier transformed infrared spectroscopy (FTIR) in attenuated total reflectance (ATR) mode showed peaks corresponding to GMA which indicates successful grafting. The X-ray diffraction (XRD) analysis revealed that the crystalline region of MCC was not adversely affected after grafting with GMA. The thermogravimetric analysis (TGA) data showed that the decomposition of grafted MCC occurred at higher temperature compared to the base MCC polymer. (author)

  7. Graft-copolymerization of hydrophilic monomers onto irradiated polypropylene fibers

    International Nuclear Information System (INIS)

    A method of graft-copolymerization of hydrophilic monomers such as 1-vinyl-2 pyrolidone, acrylonitrile, acrylic acid and acrylamide onto irradiated polypropylene fibers has been studied. Gamma ray as well as electron beam were employed for the irradiation processes. Graft copolymerization kinetics and the properties of grafted fibers have been investigated. Moisture regain, dyes absorption and the melting point of the grafted fibers increased with the increase of the degree of grafting. Polypropilen 1-vinyl-2 pyrrolidone grafted fibers showed excellent dyes absorption of almost all kinds of dyes such as direct, basic, acid, reactive, dispers, and naphtol. However for polypropylene acrylic acid grafted fibers, the colour fastness to washing was found to be unsatisfactory. The colourfastness to washing for polypropylene grafted fibers was found to be fairly good for certain dyes such as v and naphtol dyes

  8. Coronary Artery Bypass Graft Surgery (Beyond the Basics)

    Science.gov (United States)

    ... for people with coronary heart disease is called "percutaneous coronary intervention" (PCI), or "stenting." This involves using a flexible ... artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention Coronary artery bypass grafting in patients with cerebrovascular ...

  9. Graft patency in off-pump and conventional coronary artery bypass grafting for treatment of triple vessel coronary disease

    Institute of Scientific and Technical Information of China (English)

    胡盛寿; 王小启; 宋云虎; 吕锋

    2003-01-01

    Objective To compare graft patency in off-pump and conventional coronary artery bypass grafting by using the transit time flow meter in the treatment of triple vessel coronary artery disease. Methods Between June 2000 and April 2001, 60 patients with triple vessel coronary artery disease underwent coronary artery bypass grafting. They were divided into two groups: off-pump and conventional coronary artery bypass. All completed grafts were tested intraoperatively using Transit Time Flow Measurement (TTFM). Preoperative and postoperative variables of the two groups were also compared. Results There were no significant differences in sex, age, weight, acute or remote myocardial infarction, hypertension, diabetes and type of bypass grafts between the two groups. The number of bypass grafts and the assisted respiratory time of the off-pump coronary artery bypass grafting (OPCAB) group were significantly less than those of the conventional coronary artery bypass grafting (CCABG) group. The flow and pulsatile index (PI) of the left anterior descending artery bypass grafts and the right coronary artery bypass grafts were not significantly different between the OPCAB and CCABG groups. The flow of OM in the CCABG group with the multiple anastomosis site of sequential grafts was higher than that in the OPCAB group. Diffused narrow coronary artery bypass grafts in both groups had less flow.Conclusion No signficant differences in graft patency were observed in patients with triple vessel coronary artery disease who had undergone OPCAB or CCABG.

  10. Influence of silica matrix morphology on characteristics of grafted nanozirconia

    International Nuclear Information System (INIS)

    Zirconia (CZrO2=3-16wt%) coated silicas (A-380, OX-50, Si-60) were studied using XRD, XPS, FTIR, nitrogen adsorption-desorption, SEM, and quantum chemistry methods. Structure of grafted zirconia depends on the structural characteristics of the silica matrices. The XRD data show the presence of monoclinic, tetragonal and amorphous ZrO2 phases with contribution and crystallite size dependent on the matrix type. The silica gel (ZrO2 crystallite of 3-8 nm in size) or OX-50 (4-5 nm) matrices inhibit the formation of large zirconia crystallites stronger than nanosilica A-380 (13-32 nm) but more uniform ZrO2 coating is formed at the OX-50 surface. The XPS data reveal the formation of the Si-O-Zr bonds in the ZrO2/SiO2 composites, besides individual zirconia and zirconium hydroxide phases.

  11. Radiation-induced grafting of sensitive polymers

    International Nuclear Information System (INIS)

    Films of PP and PTFE were modified by gamma-radiation grafting of pH and thermo sensitive monomers (two step method) by using both the preirradiation and the direct methods. The effects of the absorbed dose, monomer concentration and reaction time were investigated. The surface chemistry of grafted samples was analyzed by FTIR-ATR spectroscopy, while their thermal properties were analyzed by TGA and DSC. The stimuli-responsive behavior was studied by swelling and contact angle in water, as well as by DSC. Sensitive films presented a critical pH and LCST. (author)

  12. Plasma Induced Grafting of PMMA onto Titanium Dioxide Powder

    Institute of Scientific and Technical Information of China (English)

    Zhong Shaofeng; Meng Yuedong; Ou Qiongrong; Xu Xu

    2005-01-01

    Grafting of polymer of methyl methacrylate (PMMA) onto titanium dioxide powder is investigated in this paper. The graft polymerization reaction is induced by dielectric-barrierdischarge produced N2 plasma treatment of titanium dioxide surfaces. IR, XPS and TGA results show that PMMA is grafted onto the surfaces of titanium dioxide powder. And crystal structure of the titanium dioxide powder observed with XRD spectra is unchanged after plasma graft polymerization.

  13. Palatal mucoperiosteal free graft: another reconstruction option for oral defects

    OpenAIRE

    Dulguerov, Pavel; Kerner, M M; Marchal, Francis; Lehmann, Willy

    1998-01-01

    Traditional methods of repair for medium-size (3-5 cm) oral defects include allowing granulation, primary closure, skin grafts, and buccal mucosal grafts. Each of these methods has several disadvantages, and all tend to result in significant scar contracture and often lack sufficient bulk. In 10 patients, the defect left by resection of cancer lesions was reconstructed with a free palatal mucoperiosteal graft. In all patients, the grafts survived with little contracture, allowing for adequate...

  14. History of free skin grafting. Knowledge of empiricism?

    OpenAIRE

    Klasen, Hendrik Jan

    1981-01-01

    In the course of more than a hundred years, skin grafting has become a standard procedure in surgery. The indications for the several types of grafting have become rather uniform.The technical aids at the operations only differ in details. Especially the vast experience gained in World War II provided the opportunity to develop the technique of skin grafting and so the evolution of present day plastics surgery. However, virtually every step in the field of indications, selection of grafts, te...

  15. Railroading technique of dermal grafting for linear atrophic scarring

    Directory of Open Access Journals (Sweden)

    Balakrishnan Nirmal

    2014-01-01

    Full Text Available Dermal grafting is a valuable technique in the field of dermatosurgery for the treatment of atrophic scars where the source of filler material is the patient′s own dermis. However, it is underused for the reasons being difficulties in placing the graft in the tunnel, keratin cysts and complications due to biofilms. Railroading technique used in urology for rupture urethra has been described for dermal grafts to overcome the technical difficulties of graft placement.

  16. Synthetic biodegradable vascular grafts for the regeneration of arteries

    OpenAIRE

    De Valence De Minardiere, Sarra

    2012-01-01

    There is an important clinical need for suitable vascular grafts, especially for small diameter vessel replacements in adult patients and for pediatric reconstructions. The objective of this thesis was to develop a synthetic biodegradable vascular graft to guide the regeneration of a natural artery. The developed graft was made of micro and nano fibers of polycaprolactone, forming a porous, but mechanically strong structure. The long term in vivo performance of the graft was evaluated in an a...

  17. Novel method of drying temporalis fascia graft for tympanomastoid surgery

    OpenAIRE

    Vikram Bhardwaj; Rohit Verma; Sanjeev Puri

    2013-01-01

    Drying the temporalis fascia graft is often an understated step in tympanomastoid surgery. Different surgeons use different methods to dry the graft. We report a novel method of drying temporalis fascia graft for tympanomastoid surgery using hot boiling water. The method is quick, easy, and safe.

  18. Revascularisation of fresh compared with demineralised bone grafts in rats

    DEFF Research Database (Denmark)

    Solheim, E; Pinholt, E M; Talsnes, O;

    2001-01-01

    Revascularisation of bone grafts is influenced by both the anatomical origin and the pre-implantation processing of the graft. We investigated the revascularisation by entrapment of 141Ce (cerium)-labelled microspheres in large, fresh and demineralised syngeneic grafts of predominantly cancellous...

  19. Polymers grafted by ionizing radiations. Regulated desorption of fertilizers

    International Nuclear Information System (INIS)

    Study and development of copolymers for progressive liberation of fertilizers in the soil through a membrane. These copolymers are obtained by grafting a hydrophilic acrylic monomer on a hydrophobic polymer (polyolefine). Desorption of a fertilizer through a membrane of graft polymer as a function of time and grafting ratio was tested both in the laboratory and by plant growing

  20. Spine Fusion Using Cell Matrix Composites Enriched in Bone Marrow-Derived Cells

    OpenAIRE

    Muschler, George F.; Nitto, Hironori; Matsukura, Yoichi; Boehm, Cynthia; Valdevit, Antonio; Kambic, Helen; Davros, William; Powell, Kimerly; Easley, Kirk

    2003-01-01

    Bone marrow-derived cells including osteoblastic progenitors can be concentrated rapidly from bone marrow aspirates using the surface of selected implantable matrices for selective cell attachment. Concentration of cells in this way to produce an enriched cellular composite graft improves graft efficacy. The current study was designed to test the hypothesis that the biologic milieu of a bone marrow clot will significantly improve the efficacy of such a graft. An established posterior spinal f...

  1. Evaluation of early coronary graft patency after coronary artery bypass graft surgery using multislice computed tomography angiography

    OpenAIRE

    Raissi Kamal; Givtaj Nader; Abdi Seifollah; Motevali Marzieh; Noohi Fereidoun; Salari Farzad; Bassri Hosseinali; Haghjoo Majid

    2009-01-01

    Abstract Background Coronary artery bypass graft (CABG) surgery is the standard of care in the treatment of advanced coronary artery disease, and its long-term results are affected by the failure of bypass grafts. The aim of the present study was to evaluate the early patency rate in coronary bypass grafts. Methods A total of 107 consecutive patients who underwent CABG were included in this study. Early graft patency was evaluated via computed tomography (CT) angiography in the first week aft...

  2. IMPROVEMENT OF TENDON REPAIR USING MUSCLE GRAFTS TRANSDUCED WITH TGF-β1 cDNA

    Science.gov (United States)

    Majewski, Martin; Porter, Ryan M.; Betz, Oliver B.; Betz, Volker M.; Clahsen, Harald; Flückiger, Rudolf; Evans, Christopher H.

    2015-01-01

    Tendon rupture is a common injury. Inadequate endogenous repair often leaves patients symptomatic, with tendons susceptible to re-rupture. Administration of certain growth factors improves tendon healing in animal models, but their delivery remains a challenge. Here we evaluated the delivery of TGF-β1 to tendon defects by the implantation of genetically modified muscle grafts. Rat muscle biopsies were transduced with recombinant adenovirus encoding TGF-β1 and grafted onto surgically transected Achilles tendons in recipient animals. Tissue regenerates were compared to those of controls by biomechanical testing as well as histochemical and immunohistochemical analyses. Healing was greatly accelerated when genetically modified grafts were implanted into tendon defects, with the resulting repair tissue gaining nearly normal histological appearance as early as 2 weeks postoperatively. This was associated with decreased deposition of type III collagen in favour of large fibre bundles indicative of type I collagen. These differences in tendon composition coincided with accelerated restoration of mechanical strength. Tendon thickness increased in gene-treated animals at weeks 1 and 2, but by week 8 became significantly lower than that of controls suggesting accelerated remodelling. Thus localised TGF-β1 delivery via adenovirus-modified muscle grafts improved tendon healing in this rat model and holds promise for clinical application. PMID:22354460

  3. Particles Bridge the Gap -- Relevance of Polymer Graft Architecture on the Properties of Particle Brush Assemblies

    Science.gov (United States)

    Bockstaller, Michael

    2011-03-01

    Current interest in the assembly of ligand-coated nanoparticles into 2D and 3D array structures is driven by the opportunities for novel material technologies that derive from the interactions within nanoparticle superlattice structures. A common challenge in the solution-based assembly of particle superlattice structures is the propensity of hard-sphere type particle assemblies to crack formation and brittle fracture during solvent evaporation. Recent progress in controlled radical polymerization offers novel opportunities for polymer-stabilized particle systems (particle brushes) as building blocks of particle superlattice structures. This contribution will discuss synthetic strategies to realize particle brush systems with well defined polymer graft-architecture in the dense or semi-dilute brush regime and discuss the effect of polymer grafting on the structure formation and cohesive interactions in particle brush assemblies. In particular, it will be demonstrated chain entanglements between surface-grafted chains give rise to fracture through polymer-like crazing thus dramatically increasing the toughness and flexibility of the particle assembly. The modulus and toughness of polymer nanocomposites synthesized by self-assembly of particle brush systems will be shown to exceed those of ``conventional'' particle-filled polymer composites -- a result that will be interpreted as a consequence of the particular conformational constraints of surface grafted chains. The author acknowledges financial support by AFOSR and DTRA.

  4. Effect of grafted polytetrafluoroethylene nanoparticles on the mechanical and tribological performances of phenol resin

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hongyan; Lu Renguo; Huang Ting; Ma Yuning; Cong Peihong [Key Laboratory of Molecular Engineering of Polymers of Ministry of Education, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Li Tongsheng, E-mail: lits@fudan.edu.cn [Key Laboratory of Molecular Engineering of Polymers of Ministry of Education, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China)

    2011-08-25

    Highlights: {yields} The addition of nano polytetrafluoroethylene particles (nano-PTFE) undergone grafting acrylic acid irradiation increased the mechanical properties of PF nanocomposites. {yields} The tribological properties of PF nanocomposites were increased by the incorporation of modified nano-PTFE. {yields} Proper amount of grafted nano-PTFE can be well separated in PF matrix. - Abstract: Reinforced phenol resin (PF) was prepared by in situ polymerization of different fractions of nano polytetrafluoroethylene particles (nano-PTFE) undergone grafting acrylic acid irradiation. The bending strength and hardness of the material, according to mechanical property testing, were improved by the grafted nano-PTFE. The tribological properties of PF composites were investigated by a block-on-ring friction and wear tester. The results indicated that nano-PTFE reinforced PF showed lower friction coefficient and higher wear resistance, compared with pure PF. The morphologies of the worn surfaces, debris and transfer films were observed by a scanning electron microscopy (SEM) and an optical microscopy (OM). A continuous and thinner transfer film formed during the friction test led to the significant improvement on the tribological properties.

  5. High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

    Science.gov (United States)

    Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

    2016-02-01

    An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

  6. Effect of grafted polytetrafluoroethylene nanoparticles on the mechanical and tribological performances of phenol resin

    International Nuclear Information System (INIS)

    Highlights: → The addition of nano polytetrafluoroethylene particles (nano-PTFE) undergone grafting acrylic acid irradiation increased the mechanical properties of PF nanocomposites. → The tribological properties of PF nanocomposites were increased by the incorporation of modified nano-PTFE. → Proper amount of grafted nano-PTFE can be well separated in PF matrix. - Abstract: Reinforced phenol resin (PF) was prepared by in situ polymerization of different fractions of nano polytetrafluoroethylene particles (nano-PTFE) undergone grafting acrylic acid irradiation. The bending strength and hardness of the material, according to mechanical property testing, were improved by the grafted nano-PTFE. The tribological properties of PF composites were investigated by a block-on-ring friction and wear tester. The results indicated that nano-PTFE reinforced PF showed lower friction coefficient and higher wear resistance, compared with pure PF. The morphologies of the worn surfaces, debris and transfer films were observed by a scanning electron microscopy (SEM) and an optical microscopy (OM). A continuous and thinner transfer film formed during the friction test led to the significant improvement on the tribological properties.

  7. Improvement of tendon repair using muscle grafts transduced with TGF-β1 cDNA

    Directory of Open Access Journals (Sweden)

    M Majewski

    2012-02-01

    Full Text Available Tendon rupture is a common injury. Inadequate endogenous repair often leaves patients symptomatic, with tendons susceptible to re-rupture. Administration of certain growth factors improves tendon healing in animal models, but their delivery remains a challenge. Here we evaluated the delivery of TGF-β1 to tendon defects by the implantation of genetically modified muscle grafts. Rat muscle biopsies were transduced with recombinant adenovirus encoding TGF-β1 and grafted onto surgically transected Achilles tendons in recipient animals. Tissue regenerates were compared to those of controls by biomechanical testing as well as histochemical and immunohistochemical analyses. Healing was greatly accelerated when genetically modified grafts were implanted into tendon defects, with the resulting repair tissue gaining nearly normal histological appearance as early as 2 weeks postoperatively. This was associated with decreased deposition of type III collagen in favour of large fibre bundles indicative of type I collagen. These differences in tendon composition coincided with accelerated restoration of mechanical strength. Tendon thickness increased in gene-treated animals at weeks 1 and 2, but by week 8 became significantly lower than that of controls suggesting accelerated remodelling. Thus localised TGF-β1 delivery via adenovirus-modified muscle grafts improved tendon healing in this rat model and holds promise for clinical application.

  8. Endothelialized ePTFE Graft by Nanobiotechnology

    Science.gov (United States)

    2013-11-29

    The Apparatus for Processing the Tubular Graft Modification Will be Designed and Evaluated.; The On-site Capturing of the Endothelial (Progenitor) Cells by Peptide-mediated Selective Adhesion in Vitro and in Vivo Will Also be Elucidated.; The Patency Rate of ITRI-made Artificial Blood Vessels Will be Evaluated by the Porcine Animal Model.

  9. Polyethylene glycol-grafted polystyrene particles

    NARCIS (Netherlands)

    Meng, Fenghua; Engbers, Gerard H.M.; Feijen, Jan

    2004-01-01

    Densely pegylated particles that can serve as a model system for artificial cells were prepared by covalently grafting amino polyethylene glycol (PEG, molecular weight 3400 or 5000) onto carboxyl polystyrene particles (PS-COOH) using carbodiimide chemistry. PEG-modified particles (PS-PEG) were chara

  10. Experimental vascular graft for liver transplantation

    NARCIS (Netherlands)

    Kobori, L; Nemeth, T; Nemes, B; Dallos, G; Sotonyi, P; Fehervari, [No Value; Patonai, A; Slooff, MJH; Jaray, J; De Jong, KP

    2003-01-01

    Hepatic artery thrombosis is a major cause of graft failure in liver transplantation. Use of donor interponates are common, but results are controversial because of necrosis or thrombosis after rejection. Reperfusion injury, hypoxia and free radical production determinate the survival. The aim of th

  11. Dynamics of solvent-free grafted nanoparticles

    KAUST Repository

    Chremos, Alexandros

    2012-01-01

    The diffusivity and structural relaxation characteristics of oligomer-grafted nanoparticles have been investigated with simulations of a previously proposed coarse-grained model at atmospheric pressure. Solvent-free, polymer-grafted nanoparticles as well as grafted nanoparticles in a melt were compared to a reference system of bare (ungrafted) particles in a melt. Whereas longer chains lead to a larger hydrodynamic radius and lower relative diffusivity for grafted particles in a melt, bulk solvent-free nanoparticles with longer chains have higher relative diffusivities than their short chain counterparts. Solvent-free nanoparticles with short chains undergo a glass transition as indicated by a vanishing diffusivity, diverging structural relaxation time and the formation of body-centered-cubic-like order. Nanoparticles with longer chains exhibit a more gradual increase in the structural relaxation time with decreasing temperature and concomitantly increasing particle volume fraction. The diffusivity of the long chain nanoparticles exhibits a minimum at an intermediate temperature and volume fraction where the polymer brushes of neighboring particles overlap, but must stretch to fill the interparticle space. © 2012 American Institute of Physics.

  12. Grafting increases lycopene in seedless watermelon

    Science.gov (United States)

    Although watermelon grafting has been done for years in Asia and Europe, this production method is still novel to the U.S. Fruit from four rootstocks with scions of the seedless watermelons Palomar, TriX313, Matrix, and Petite Perfection were compared for soluble solids content, pH, and carotenoids...

  13. Cellular grafts in management of leucoderma

    Directory of Open Access Journals (Sweden)

    Mysore Venkataram

    2009-01-01

    Full Text Available Cellular grafting methods constitute important advances in the surgical management of leucoderma. Different methods such as noncultured epidermal suspensions, melanocyte cultures, and melanocyte-keratinocyte cultures have all been shown to be effective. This article reviews these methods.

  14. Cultured keratinocyte grafting on various biologic matrices

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Objective: To make attempts to use cell constructs from subconfluent keratinocyte cultures, which contain a much glue (TissucollR) and directly applied onto full thickness wounds in athymic mice or combined with allogenic split thickness overgrafts and compared with cultured sheet grafts. This keratinocyte fibrin glue suspension (KFGS) has also been used in burns up to 88% burned TBSA as well as in chronic wounds. Keratinocytes were also seeded onto various biomaterials (BiobraneR, HYAFF LaserskinR, IntegraTM, TissuFascieR) as carriers. Results: Human suspended keratinocytes were effective to reorganize to skin in vivo both in nude mice and in patients and superior if compared to sheet grafts. 3~ 5 d after seeding onto various biomaterials, cell reached subconfluence and were ready for grafting. These cell-membrane constructs were always tured on microspheres in spinner cultures could increase the cell yield, and the subconfluently covered microspheres were directly grafted onto" the wound. Conclusion: These experiments demonstrated that keratinocytes can grow on a variety of carrier materials in vitro and these cell constructs were able to spontaneously reform a multilayer neoepithelium in vivo. The current screening looks for the ideal carrier for keratinocytes that also would serve as a temporary wound cover and induce dermis formation by tissue conduction which further may be enhanced by gene therapy.

  15. Grafting functional antioxidants on highly crosslinked polyethylene

    Science.gov (United States)

    Al-Malaika, S.; Riasat, S.; Lewucha, C.

    2016-05-01

    The problem of interference of antioxidants, such as hindered phenols, with peroxide-initiated crosslinking of polyethylene was addressed through the use of functional (reactive) graftable antioxidants (g-AO). Reactive derivatives of hindered phenol and hindered amine antioxidants were synthesised, characterised and used to investigate their grafting reactions in high density polyethylene; both non-crosslinked (PE) and highly peroxide-crosslinked (PEXa). Assessment of the extent of in-situ grafting of the antioxidants, their retention after exhaustive solvent extraction in PE and PEXa, and the stabilising performance of the grafted antioxidants (g-AO) in the polymer were examined and benchmarked against conventionally stabilised crosslinked & non-crosslinked polyethylene. It was shown that the functional antioxidants graft to a high extent in PEXa, and that the level of interference of the g-AOs with the polymer crosslinking process was minimal compared to that of conventional antioxidants which bear the same antioxidant function. The much higher level of retention of the g-AOs in PEXa after exhaustive solvent extraction, compared to that of the corresponding conventional antioxidants, accounts for their superior long-term thermal stabilising performance under severe extractive conditions.

  16. Anterior cervical allograft arthrodesis and instrumentation: Multilevel interbody grafting or strut graft reconstruction

    OpenAIRE

    Swank, M. L.; Lowery, G. L.; Bhat, A. L.; McDonough, R. F.

    1997-01-01

    This retrospective study evaluated a single surgeon's series of patients treated by multilevel cervical disc excision (two or three levels), allograft tricortical iliac crest arthrodesis, and anterior instrumentation. The objective of this retrospective study was to compare fusion success and clinical outcome between multilevel Smith-Robinson interbody grafting and tricortical iliac strut graft reconstruction, both supplemented with anterior instrumentation in the cervical spine. The incidenc...

  17. ‘Minipatch’ penile skin graft urethroplasty in the era of buccal mucosal grafting

    OpenAIRE

    Hudak, Steven J.; Hudson, Tillman C.; Allen F. Morey

    2012-01-01

    Objectives To describe our experience with ‘minipatch’ penile skin graft (PSG) urethroplasty, as at our institution we prefer excision and primary anastomosis (EPA) urethroplasty whenever feasible, as it gives better outcomes than substitution urethroplasty. However, despite careful preoperative planning, the unanticipated need for a small graft is occasionally recognised intra-operatively, and in such cases we have found that harvesting a minipatch is an efficient alternative to harvesting a...

  18. Synthesis of Polymer Grafted Magnetite Nanoparticle with the Highest Grafting Density via Controlled Radical Polymerization

    OpenAIRE

    Babu Kothandapani; Dhamodharan Raghavachari

    2009-01-01

    Abstract The surface-initiated ATRP of benzyl methacrylate, methyl methacrylate, and styrene from magnetite nanoparticle is investigated, without the use of sacrificial (free) initiator in solution. It is observed that the grafting density obtained is related to the polymerization kinetics, being higher for faster polymerizing monomer. The grafting density was found to be nearly 2 chains/nm2for the rapidly polymerizing benzyl methacrylate. In contrast, for the less rapidly polymerizing styren...

  19. β2 integrins separate graft-versus-host disease and graft-versus-leukemia effects

    OpenAIRE

    Liang, Yaming; Liu, Chen; Djeu, Julie Y.; Zhong, Bin; Peters, Thorsten; Scharffetter-Kochanek, Karin; Anasetti, Claudio; Yu, Xue-Zhong

    2008-01-01

    Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality in allogeneic hematopoietic stem cell transplantation. Migration of donor-derived T cells into GVHD target organs plays an essential role in the development of GVHD. β2 integrins are critically important for leukocyte extravasation through vascular endothelia and for T-cell activation. We asked whether CD18-deficient T cells would induce less GVHD while sparing the graft-versus-leukemia (GVL) effect. In murine a...

  20. Targeting minor histocompatibility antigens in graft versus tumor or graft versus leukemia responses

    OpenAIRE

    Feng, Xin; Hui, Kwok Min; Younes, Hashem M.; Brickner, Anthony G.

    2008-01-01

    Allogeneic hematopoietic cell transplantation (alloHCT) represents the only curative therapy for several hematologic malignancies, and shows promise as a nascent treatment modality for select solid tumors. Although the original goal of alloHCT was hematopoietic reconstitution after sub-lethal chemoradiotherapy, recognition of a profound donor lymphocyte-mediated graft-versus-leukemia (GVL) or graft-versus-tumor (GVT) effect has shifted the paradigm from pre-transplant cytoreduction to tumor c...

  1. Design of Chitosan-Grafted Carbon Nanotubes: Evaluation of How the –OH Functional Group Affects Cs+ Adsorption

    OpenAIRE

    Shubin Yang; Dadong Shao; Xiangke Wang; Guangshun Hou; Masaaki Nagatsu; Xiaoli Tan; Xuemei Ren; Jitao Yu

    2015-01-01

    In order to explore the effect of –OH functional groups in Cs+ adsorption, we herein used the low temperature plasma-induced grafting method to graft chitosan onto carbon nanotubes (denoted as CTS-g-CNTs), as raw-CNTs have few functional groups and chitosan has a large number of –OH functional groups. The synthesized CTS-g-CNT composites were characterized using different techniques. The effect of –OH functional groups in the Cs+ adsorption process was evaluated by comparison of the adsorptio...

  2. Studies on radiation-induced graft copolymerization to make polymer surfaces hydrophilic and on antithrombogenicity of the surfaces obtained

    International Nuclear Information System (INIS)

    The thrombus formation reaction on the polymer surfaces, which is a sensitive elaborate defense system in living body to the invasion of foreign substances, is supposed to be triggered by adsorption and denaturation of proteins in blood. Accordingly, the polymer surfaces made highly hydrophilic have been expected to give high antithrombogenic surface because they may little interact with the proteins. Hence, the author studied systematically on radiation-induced graft copolymerization to make hydrophobic polymer surfaces hydrophilic and on the relation between the surface composition or properties and antithrombogenicity of the grafted surfaces obtained. The results are summarized. (J.P.N.)

  3. Numerical Simulation of Coronary Artery Bypass Graft with an Assistant Graft

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; WANG Feng

    2014-01-01

    The conventional bypass design is to implant a graft on the stenosed host artery allowing blood to flow bypass the stenotic artery. However, restenosis is a challenging problem which finally results in reoperation. The purpose of this paper is to propose a new bypass graft design of coronary artery with an assistant graft for the treatment of coronary artery stenosis. An additional assistant graft was employed in the new design compared with the conventional ETS anastomosis. Numerical simulations were performed by means of finite volume method using computational fluid dynamics (CFD) solver. Results demonstrated that the new anastomoses model provided a more smooth flow at the distal ETS anastomosis without any stagnation point on anastomotic bed and vortex formation in the heel region. Oscillatory shear index (OSI) and time-averaged wall shear stress gradient (TAWSSG) at the artery bed of the distal ETS anastomosis were reduced. The coronary artery bypass graft with an assistant graft is feasible to improve the local hemodynamics and diminish the probability of restenosis in the treatment of coronary artery stenosis.

  4. Synthesis of Polymer Grafted Magnetite Nanoparticle with the Highest Grafting Density via Controlled Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Babu Kothandapani

    2009-01-01

    Full Text Available Abstract The surface-initiated ATRP of benzyl methacrylate, methyl methacrylate, and styrene from magnetite nanoparticle is investigated, without the use of sacrificial (free initiator in solution. It is observed that the grafting density obtained is related to the polymerization kinetics, being higher for faster polymerizing monomer. The grafting density was found to be nearly 2 chains/nm2for the rapidly polymerizing benzyl methacrylate. In contrast, for the less rapidly polymerizing styrene, the grafting density was found to be nearly 0.7 chain/nm2. It is hypothesized that this could be due to the relative rates of surface-initiated polymerization versus conformational mobility of polymer chains anchored by one end to the surface. An amphiphilic diblock polymer based on 2-hydroxylethyl methacrylate is synthesized from the polystyrene monolayer. The homopolymer and block copolymer grafted MNs form stable dispersions in various solvents. In order to evaluate molecular weight of the polymer that was grafted on to the surface of the nanoparticles, it was degrafted suitably and subjected to gel permeation chromatography analysis. Thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to confirm the grafting reaction.

  5. Soft tissue grafting to improve implant esthetics

    Directory of Open Access Journals (Sweden)

    Moawia M Kassab

    2010-09-01

    Full Text Available Moawia M KassabDivision of Periodontics, Marquette University, School of Dentistry, Milwaukee, WI, USAAbstract: Dental implants are becoming the treatment of choice to replace missing teeth, especially if the adjacent teeth are free of restorations. When minimal bone width is present, implant placement becomes a challenge and often resulting in recession and dehiscence around the implant that leads to subsequent gingival recession. To correct such defect, the author turned to soft tissue autografting and allografting to correct a buccal dehiscence around tooth #24 after a malpositioned implant placed by a different surgeon. A 25-year-old woman presented with the chief complaint of gingival recession and exposure of implant threads around tooth #24. The patient received three soft tissue grafting procedures to augment the gingival tissue. The first surgery included a connective tissue graft to increase the width of the keratinized gingival tissue. The second surgery included the use of autografting (connective tissue graft to coronally position the soft tissue and achieve implant coverage. The third and final surgery included the use of allografting material Alloderm to increase and mask the implant from showing through the gingiva. Healing period was uneventful for the patient. After three surgical procedures, it appears that soft tissue grafting has increased the width and height of the gingiva surrounding the implant. The accomplished thickness of gingival tissue appeared to mask the showing of implant threads through the gingival tissue and allowed for achieving the desired esthetic that the patient desired. The aim of the study is to present a clinical case with soft tissue grafting procedures.Keywords: case report, connective tissue, dental implants, allograft, coronally positioned flap

  6. Humidity Sensing Properties of Pre-irradiation Grafted HDPE Membranes

    Institute of Scientific and Technical Information of China (English)

    Zheng Jiao; Qun Fu; Xiang Geng; Zhen Li; Haijian Zhong

    2006-01-01

    Grafted high density polyethylene (HDPE) films have been prepared by grafting sodium styrene sulfonate (SSS) and acrylic acid (AA) onto HDPE using preirradiation method. The structure and surface morphology of both grafted and ungrafted HDPE films were observed by FTIR spectroscopy and scanning electron microscope (SEM), respectively. The humidity sensing properties of grafted HDPE films were investigated. The results show that the impedance of the film decreases with increasing of relative humidity (RH). The films display high sensitivity with nearly three orders of magnitude change in the resistance during the relative humidity variation from 5% to 98%. Grafted HDPE films exhibit excellent properties as humidity sensors.

  7. Preparation and physical properties of grafted bagasse pulp metal complexes

    International Nuclear Information System (INIS)

    The effect of grafting on the electrical properties of bleached bagasse pulp has been investigated over a frequency range 1-200 Khz. The conductivity increases upon grafting with acrylic acid or acrylonitrile. Grafted bleached bagasse pulp with acrylic acid showed an increase in the dielectric constant ε and dielectric loss ε. The bagasse/acrylic acid copolymer metal complexes have shown further increase in the conductivity. The conductivity decreases as the degree of grafting increased from 25% to 215%, indicating slower rate of complexation at higher grafting percentage

  8. Radiation grafting of pH-sensitive acrylic acid and 4-vinyl pyridine onto nylon-6 using one- and two-step methods

    Science.gov (United States)

    Ortega, Alejandra; Alarcón, Darío; Muñoz-Muñoz, Franklin; Garzón-Fontecha, Angélica; Burillo, Guillermina

    2015-04-01

    Acrylic acid (AAc) and 4-vinyl pyridine (4VP) were γ-ray grafted onto nylon-6 (Ny6) films via pre-irradiation oxidative method. These monomers were grafted using a one-step method to render Ny6-g-(AAc/4VP). A two-step or sequential method was used to render (Ny6-g-AAc)-g-4VP. Random copolymer branches were obtained when the grafting was carried out via one-step method using the two monomers together. The two-step method was applied to graft chains of 4VP on both Ny6 substrate and previously grafted AAc chains (Ny6-g-AAc). The two types of binary copolymers synthesized were characterized to determine the amount of grafted polymers, the thermal behavior (DSC and TGA), the surface composition (XPS), and the pH responsiveness. In the two-step process, it is possible to achieve a higher graft yield, better control of the amount of each monomer, good reversibility in the swelling/deswelling process and shorter time to achieve equilibrium swelling.

  9. Radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate)

    International Nuclear Information System (INIS)

    The graft copolymer poly (3-hydroxybutyrate)-g- polyacrylamide [P (HB-g-AAm)] was synthesized by radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate). The study was conducted by the simultaneous irradiation method. The structure of [P (HB-g-AAm)] was identified by Fourier Transform Infrared (FTIR) spectroscopy. Thermal behavior of the graft copolymer was also studied by Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). From the results it was found that FTIR studies showed new signals (stretching -N-H) as strong evidence of grafting. The grafting degree was found to be 10 % and the thermodynamic parameter obtained from the DSC thermogram of plain PHB and the graft copolymer varied showing decrease in the material crystallinity and increase in the glass transition temperature. These results demonstrate that the radiation induced graft copolymerization reaction of acrylamide onto PHB was successively achieved. (Author)

  10. Free and microvascular bone grafting in the irradiated dog mandible

    International Nuclear Information System (INIS)

    Microvascular and free rib grafts were placed in 4.5 cm defects in an edentate mandibular body defect 18 to 28 days after completion of 50 Gy of irradiation from a 60Co source. The animals were sacrificed from two to forty weeks postoperatively and evaluated clinically, radiographically, and histologically. There was a marked difference in the alveolar mucosal viability with the two grafts. Mucosal dehiscence was not observed over any of the microvascular grafts, but was present in seven-eighths of the free grafts. Union of the microvascular bone graft to the host bone occurred within six weeks. In contrast, after six weeks the free graft was sequestered in all the animals. An unexpected finding with both types of graft was the marked subperiosteal bone formation. This bone appeared to be derived from the host bed, stabilizing and bridging the defects bilaterally. The results suggest that radiated periosteum may play an important role in osteogenesis

  11. Combined bone grafting: an alternative method for bone healing stimulation

    International Nuclear Information System (INIS)

    The most provocative problem in bone grafting is the effectiveness of healing of the graft. When you use the heterogenous bone graft, it may take one or more than two years for consolidation and union depends on the graft quality and the situation of surrounding blood supply. In our preliminary report seven cases of freeze-dried heterogenous bone graft from the Bangkok Biomaterial Center were mixed with autogenous iliac bone graft from the patient in the ratio of 3:1. After that the healing was checked by clinical examination and X-ray in the periodic follow up. The causes of bone lost are post evacuation of benign bone tumor and post infection of bone after trauma. The result of bony union could be tested by clinical examination and showed in the X-ray films as early as 3 months post grafting

  12. ESR spectroscopic investigations of the radiation-grafting of fluoropolymers

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, G.; Roduner, E. [University of Stuttgart (Germany); Brack, H.P.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    ESR spectroscopic investigations have clarified the influence of several preparative parameters on the reaction rates and yields obtained in the radiation-grafting method used at PSI to prepare proton-conducting polymer membranes. At a given irradiation dose, a higher concentration of reactive radical sites was detected in ETFE films than in FEP films. This higher concentration explains the higher grafting levels and rates of the ETFE films found in our previous grafting experiments. Taken together, the in-situ ESR experiments and grafting experiments show that the rates of disappearance of radical species and grafting rates and final grafting levels depend strongly on the reaction temperature and the oxygen content of the system. Average grafted chain lengths were calculated to contain about 1,000 monomer units. (author) 2 figs., 4 refs.

  13. Successful treatment of an infected thoracic endovascular stent graft.

    Science.gov (United States)

    Sueda, Taijiro; Takahashi, Shinya; Katayama, Keijiro; Imai, Katsuhiko

    2016-05-01

    A 70-year-old man with a chronic type B aortic dissection was treated with two stent grafts deployed in the descending thoracic aorta. The patient was re-admitted to the hospital at 16 months after thoracic endovascular stent grafting because of a high fever. A blood culture showed sepsis due to a Staphylococcus species. A CT scan showed an increase in the size of the thrombosed false lumen. Complete excision of the infected descending aortic wall and infected stent graft were performed. The descending thoracic aorta was reconstructed using a rifampicin-bonded Dacron graft and omental wrapping. The combination of in situ graft replacement using a rifampicin-bonded graft and omental wrapping is considered an effective treatment for thoracic stent graft infection. PMID:24990657

  14. Radiation grafting of acrylonitrile on ethylene-propylene diene terpolymer rubber. Optimization of grafting parameters and oil resistance properties

    International Nuclear Information System (INIS)

    Radiation induced grafting of acrylonitrile (ACN) on ethylene-propene diene terpolymer (EPDM) rubber film was investigated by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, type of solvent and monomer content on extent of grafting was studied. From the kinetic studies a mathematical relation Rgα[M]0.7D0.68 showing non-linear relationship for rate of grafting with monomer concentration and dose was deduced. The grafted samples showed increased hardness and oil resistance. (author)

  15. Design, synthesis, and initial evaluation of D-glyceraldehyde crosslinked gelatin-hydroxyapatite as a potential bone graft substitute material

    Science.gov (United States)

    Florschutz, Anthony Vatroslav

    Utilization of bone grafts for the treatment of skeletal pathology is a common practice in orthopaedic, craniomaxillofacial, dental, and plastic surgery. Autogenous bone graft is the established archetype but has disadvantages including donor site morbidity, limited supply, and prolonging operative time. In order to avoid these and other issues, bone graft substitute materials are becoming increasingly prevalent among surgeons for reconstructing skeletal defects and arthrodesis applications. Bone graft substitutes are biomaterials, biologics, and guided tissue/bone regenerative devices that can be used alone or in combinations as supplements or alternatives to autogenous bone graft. There is a growing interest and trend to specialize graft substitutes for specific indications and although there is good rationale for this indication-specific approach, the development and utility of a more universal bone graft substitute may provide a better answer for patients and surgeons. The aim of the present research focuses on the design, synthesis, and initial evaluation of D-glyceraldehyde crosslinked gelatin-hydroxyapatite composites for potential use as a bone graft substitutes. After initial establishment of rational material design, gelatinhydroxyapatite scaffolds were fabricated with different gelatin:hydroxyapatite ratios and crosslinking concentrations. The synthesized scaffolds were subsequently evaluated on the basis of their swelling behavior, porosity, density, percent composition, mechanical properties, and morphology and further assessed with respect to cell-biomaterial interaction and biomineralization in vitro. Although none of the materials achieved mechanical properties suitable for structural graft applications, a reproducible material design and synthesis was achieved with properties recognized to facilitate bone formation. Select scaffold formulations as well as a subset of scaffolds loaded with recombinant human bone morphogenetic protein-2 were

  16. Comparison of mesencephalic free-floating tissue culture grafts and cell suspension grafts in the 6-hydroxydopamine-lesioned rat

    DEFF Research Database (Denmark)

    Meyer, Morten; Widmer, H R; Wagner, B;

    1998-01-01

    Ventral mesencephalon (VM) of fetal rat and human origin grown as free-floating roller-tube (FFRT) cultures can survive subsequent grafting to the adult rat striatum. To further explore the functional efficacy of such grafts, embryonic day 13 ventral mesencephalic tissue was grafted either after 7......-term survival of grafted dopaminergic neurons and to correlate that with the behavioral effects. Additional cultures and acutely prepared explants were also fixed and stored for histological investigation in order to estimate the loss of dopaminergic neurons in culture and after transplantation. Similar...... similar numbers of TH-immunoreactive (TH-ir) neurons in grafts of cultured tissue (775 +/- 98, mean +/- SEM) and grafts of fresh, dissociated cell suspension (806 +/- 105, mean +/- SEM). Cell counts in fresh explants, 7-day-old cultures, and grafted cultures revealed a 68.2% loss of TH-ir cells 7 days...

  17. In vitro release studies of vitamin B12 from poly N-vinyl pyrrolidone /starch hydrogels grafted with acrylic acid synthesized by gamma radiation

    International Nuclear Information System (INIS)

    Co-polymeric hydrogels containing N-vinyl pyrrolidone and starch grafted with acrylic acid were synthesized by gamma radiation. Their gel contents, grafting process and swelling were evaluated. The gels were also characterized by thermal gravimetric analysis. The gel content found to be increase with increasing the irradiation dose up to 50 kGy then decrease. The grafting percent increase by increasing the percentage of acrylic acid in the grafted hydrogels. The thermal stability and the rate of the thermal decomposition showed to be changed according to the different composition of the hydrogels. It also showed a decrease in the maximum rate of the thermal decomposition by the increasing of the irradiation dose from 20 to 30 kGy and increases by increasing the irradiation dose from 30 to 70 kGy. The hydrogels loaded with vitamin B12 as drug model, demonstrated a decrease release in acidic medium than the neutral one

  18. Growth and conversion of solar energy of grafted tomato plants under protected cultivation

    OpenAIRE

    Tiago Pedó; Tiago Zanatta Aumonde; Nei Fernandes Lopes; Carlos Rogério Mauch

    2015-01-01

    The grafting technique favors cultivation tomato under conditions environment adverse, being the effects on the physiology of scarce plants. Thus, this study aimed to evaluate the growth and solar energy conversion efficiency in grafted tomato and not grafted in greenhouse. The grafting was performed by grafting of cleft and the treatments consisted of tomato plants grafted on hybrid Kaguemusha® and not grafted. The samples for growth analysis were performed at intervals of fourteen days afte...

  19. Synthesis and characterization of nanocomposites from amphipathy polyester grafted modified sericite and methylsilicone resin

    International Nuclear Information System (INIS)

    The synthetic process of amphipathy polyester grafted modified sericite and methylsilicone resin composites is studied. The analytical results showed that the initial decomposition temperature and the maximum release energy corresponding temperature are enhanced 120 °C and 51 °C. First, modified methylsilicone resin molecular structure is designed. Molecular chair of methylsilicone resin is grafted macromolecular polymer, which is synthesized by toluene-2, 4-diisocyanate modified sericite grafted amphipathy polyester. A modified sericite /methylsilicone resin composites are synthesized through the reaction of functionalized sericite with hydroxyl-terminated methylsilicone resin. X-ray diffraction analysis result showed that the methylsilicone resin has reacted with the modified sericite. Infrared spectra, x-ray photoelectron spectroscopy and nuclear magnetic resonance analysis show that the weak Si-OH band decreases and the strong Si-O-Si band increases. The mechanism of thermal stability is analyzed from the isolated oxygen atom and activated small molecule; interrupted activated Si-OH, steric hindrance. The result of study evidently shows a significant role in enhancing the decomposition temperature of the methylsilicone resin. (papers)

  20. Aircast Award for Basic Science - The Effect of Dynamic Changes in ACL Graft Force on Soft Tissue ACL Graft-Tunnel Incorporation

    OpenAIRE

    Ma, Richard; Schaer, Michael; Chen, Tina; Sisto, Marco; Voigt, Clifford; Nguyen, Joseph; Ying, Lilly; Deng, Xiang-hua; Rodeo, Scott A.

    2014-01-01

    Objectives: Anterior cruciate ligament grafts that are placed for reconstruction are subject to complex forces with joint motion. Current “anatomic” ACL reconstructions result in greater in situ graft forces. The biologic effect of changing magnitudes of ACL graft force on graft-tunnel osseointegration is not completely understood. The objective of the present study is to determine the effects of dynamic mechanical ACL graft tension or load on graft-tunnel incorporation. Methods: One hundred ...

  1. Five-year outcomes following a randomized trial of femorofemoral and femoropopliteal bypass grafting with heparin-bonded or standard polytetrafluoroethylene grafts

    DEFF Research Database (Denmark)

    Lindholt, J S; Houlind, K; Gottschalksen, B;

    2016-01-01

    BACKGROUND: Cohort studies suggest superior long-term patency of luminal heparin-bonded polytetrafluoroethylene (Hb-PTFE) bypass grafts compared with standard PTFE grafts. The aim of this study was to compare the outcomes of Hb-PTFE grafts with those of standard PTFE grafts 5 years after a random...... likely to have a patent graft at 5 years than those with standard PTFE grafts....

  2. Rheological properties of long-chain branched chlorinated poly(isobutylene-co-isoprene)-graft-polybutadiene terpolymers (CIIR-g-BR)

    Science.gov (United States)

    Sendorek, Jerzy (George)

    Anionically polymerized "living" polybutadiene (BR) was grafted onto chlorinated poly(isobutylene-co-isoprene) (CIIR) to form a series of elastomeric graft copolymers (CIIR-g-BR) of comb-type, long-chain branching structure (LCB) with systematically varying length and number of branches. A comprehensive program of analytical characterization of the structure and morphology of these materials using SEC/DRI-DV, NMR, FT-IR, DSC, TGA, TEM and other techniques, was designed to determine all relevant structural variables and parameters, as well as to exclude the presence of the potential compositional interferences (gel, residual solvent, unattached branch parent polymer, etc.) for intended correlations between branching structure and rheological properties. The principal branching characteristics of comb-like long-chain branched structures were derived from the stoichiometry of the grafting reaction, confirmed by compositional analysis using a combination of NMR/FT-IR/SEC and supplemented by SEC characterization of the parent linear polymers constituting the backbone (CIIR) and the branch of the graft (BR), respectively. Linear viscoelastic properties of these materials were determined by a Rheometrics Mechanical Spectrometer (RMS-800) using small amplitude, dynamic (sinusoidal oscillatory) shear. These measurements were supplemented by Rubber Process Analyzer (RPA 2000sp{TM}) testing in a comparable range of strain amplitudes, frequencies and temperatures. Stress relaxation experiments, following small amplitude step-strain in shear, complemented the dynamic mechanical measurement. Non-linear viscoelastic properties in shear were investigated in a series of isothermal strain and frequency sweeps using large strain (up to 800%) oscillations (RPA 2000), and by stress following a large-amplitude (˜75%) step shear strain, using the Dynamic Stress Relaxometer (DSR). An insight into the morphology of the grafts by means of the TEM and DSC has been compared to the results of

  3. Preparation of thermosensitive membranes by radiation grafting of acrylic acid/ N-isopropyl acrylamide binary mixture on PET fabric

    Science.gov (United States)

    Gupta, Bhuvanesh; Mishra, Swaiti; Saxena, Shalini

    2008-05-01

    Thermosensitive membranes were prepared by radiation-induced graft copolymerization of monomers on PET fabrics. A binary mixture of N-isopropyl acrylamide (NIPAAm) and acrylic acid (AA) was grafted on polyester fabric as a base material to introduce thermosensitive poly( N-isopropyl acrylamide) pendant chains having LCST slightly higher than 37 °C in the membrane. The influence of ferrous sulfate, radiation dose and monomer composition on the degree of grafting was studied. The structure of the grafted fabric was characterized by thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy. The thermosensitive nature of the fabric was monitored by swelling at different temperatures. The graft copolymerization of AA with NIPAAm enhanced the LCST of the resultant membrane to ˜37 °C. The moisture vapor transmission rate (MVTR) and air permeability of the fabric decreased slightly, may be due to the slight blocking of the fabric pores. The immobilization of tetracycline hydrochloride as the model drug and its release characteristics at different temperatures were monitored.

  4. Enhancement of stiffness, strength, ductility and toughness of poly(ethylene oxide) using phenoxy-grafted multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Phenoxy (poly(hydroxyether of bisphenol-A), also known as poly(bisphenol-A-co-epichlorohydrin)) was grafted onto multiwalled carbon nanotubes (MWNTs) by a reactive blending process. Reactions between terminal glycidyl groups of phenoxy and carboxylic acid groups of acidified MWNTs resulted in the grafting of phenoxy chains onto MWNTs. The mechanical properties of composites of poly(ethylene oxide) (PEO) and phenoxy-grafted MWNTs were studied. The miscibility between PEO and phenoxy enabled the good dispersion of nanotubes in the PEO matrix as evidenced by polarized optical microscopy and transmission electron microscopy. The spherulite size of PEO progressively decreased with increasing amount of phenoxy-grafted MWNTs added. At an optimal MWNT content of 1.5 wt%, the addition of phenoxy-grafted MWNTs led to increases of storage modulus, Young's modulus, yield stress, tensile strength, ultimate strain, and toughness of PEO by 113, 228, 166, 442, 1240, and 4080%, respectively. Such simultaneous increases in stiffness, strength, ductility and toughness of a polymer by an additive are rather uncommon

  5. The addition of soft tissue replacement grafts in plastic periodontal and implant surgery: critical elements in design and execution.

    Science.gov (United States)

    Zuhr, Otto; Bäumer, Daniel; Hürzeler, Markus

    2014-04-01

    Soft tissue replacement grafts have become a substantial element to increase tissue volume in plastic periodontal and implant surgery. Autogenous subepithelial connective tissue grafts are increasingly applied in aesthetic indications like soft tissue thickening, recession treatment, ridge preservation, soft tissue ridge augmentation and papilla re-construction. For the clinical performance of connective tissue graft harvesting and transplantation, a fundamental understanding of the anatomy at the donor sites and a sound knowledge of tissue integration and re-vascularization processes are required. Possible donor sites are the anterior and posterior palate including the maxillary tuberosity, providing grafts of distinct geometric shape and histologic composition. The selective clinical application of different grafts depends on the amount of required tissue, the indication and the personal preference of the treating surgeon. One of the main future challenges is to volumetrically evaluate and compare the efficacy and long-term stability of soft tissue autografts and their prospective substitutes. The aim of this review was to discuss the advantages and shortfalls of different donor sites, substitute materials and harvesting techniques. Although standardized recommendations regarding treatment choice and execution can hardly be given, guidelines for predictable and successful treatment outcomes are provided based on clinical experience and the available scientific data. PMID:24640997

  6. Grafting of Interpenetrating Networks of Two Stimuli-responsive Polymers onto PP

    International Nuclear Information System (INIS)

    chemical polymerization and crosslinking of NIPAAm: with a crosslinking agent (MBAAm), N, N, N',N'-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) as redox initiator. With the synthesis of the last network, we have new films which are a full IPN grafted onto PP: net-(PP-g-PAA)-inter-net-PNIPAAm, synthesized in three steps. These films were characterized in their thermal and pH properties (limited swelling, contact angle, pH 'cloud point' and LCST), chemical composition (FTIR), thermal properties (DSC and TGA) and morphology (SEM)

  7. A study on the morphology of polystyrene-grafted poly(ethylene-alt-tetrafluoroethylene) (ETFE) films prepared using a simultaneous radiation grafting method

    International Nuclear Information System (INIS)

    The morphology of polystyrene-grafted poly(ethylene-alt-tetrafluoroethylene) (ETFE) films prepared using a simultaneous radiation grafting method was investigated using DMA, DSC, XRD, and SAXS instruments. The DMA study indicates that the ETFE amorphous phase and PS amorphous phase are mixed well in the PS-grafted ETFE films while the ETFE crystalline phase and the PS amorphous phase are separated, suggesting that the PS chains are grafted mainly on the ETFE amorphous regions. The DSC and XRD data showed that the natural crystalline structures of ETFE in the grafted ETFE films are not affected by the degree of grafting. The SAXS profiles displayed that the inter-crystalline distance of the ETFE films increases with an increasing degree of grafting, which further implies that the PS graft chains formed by the simultaneous irradiation has a significant impact on the amorphous morphology of the resulting grafted ETFE film. Thus, these results indicate that the styrene monomers are mainly grafted on the ETFE amorphous regions during the simultaneous radiation grafting process. - Highlights: • PS-grafted ETFE films were prepared by a simultaneous radiation grafting method was investigated. • The natural crystalline structures of grafted ETFE films are not affect by the degree of grafting. • The inter-crystalline distance of the ETFE films increase with increasing degree of grafting. • The styrene monomers are mainly grafted on the ETFE amorphous regions during a simultaneous radiation grafting using gamma-ray

  8. Novel anterior cruciate ligament graft fixation device reduces slippage

    Directory of Open Access Journals (Sweden)

    Lopez MJ

    2013-05-01

    Full Text Available Mandi J Lopez,1 Allen Borne,2 W Todd Monroe,3 Prakash Bommala,1 Laura Kelly,1 Nan Zhang11Laboratory for Equine and Comparative Orthopedic Research, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, 2Louisiana State University, New Orleans Health Sciences Center, School of Medicine, New Orleans, 3Department of Biological and Agricultural Engineering, Agricultural Center, Louisiana State University, Baton Rouge, LA, USAAbstract: Clinically significant laxity occurs in 10%–30% of knees after anterior cruciate ligament reconstruction. Graft slippage and tension loss at the hamstring graft tibial fixation site during and after reconstruction surgery contribute to postoperative joint laxity and are detrimental to long-term knee stability and graft properties. Limiting graft slippage will reduce associated complications. We sought to compare the in vitro mechanical properties and in vivo joint stabilization, postoperative limb use, and graft incorporation of the novel GraftGrab™ (GG device designed to reduce hamstring graft tibial fixation slippage with the commercially available bioabsorbable Bio-Post™ and spiked washer (BP. Mechanical testing was performed on canine tibia-hamstring graft constructs to quantify initial fixation properties. In vivo joint stabilization, postoperative limb use and graft incorporation of hamstring graft reconstructions were determined in a canine model. Outcomes included tibial translation and ground reaction forces preoperatively and 4 and 8 weeks postoperatively, three-dimensional graft and bone tunnel dimensions at the latter two time points, and graft-bone microstructure, as well as mechanical properties 8 weeks after implantation. Immediately after fixation, all grafts slipped from the BP constructs versus about 30% of GG constructs. In vivo limb use remained low, and tibial translation increased with time in the BP cohort. These results together

  9. Modification of polyetherurethane for biomedical application by radiation-induced grafting. I. Grafting procedure, determination of mechanical properties, and chemical modification of grafted films

    International Nuclear Information System (INIS)

    Radiation grafting of monomers onto suitable trunk polymers is a useful tool for tailoring new polymers for special purposes. This technique has been used in the past for the development of biocompatible materials, e.g., by grafting hydrogels onto mechanically stable polymers. In this first part of our work, the radiation grafting of hydrophilic or reactive monomers onto a polyetherurethane film using the pre-swelling technique is described. Following this technique the trunk polymer was swollen in the monomer before irradiation. As monomers 2-hydroxyethyl methacrylate (HEMA), 2,3-epoxypropyl methacrylate (GMA), 2,3-dihydroxypropyl methacrylate (GOMA), and acrylamide (AAm) were used. The kinetics of the grafting reactions were examined, and the distribution of the graft component inside the trunk polymer was investigated by means of infrared (IR) spectroscopy. Surface-grafted as well as bulk- and surface-grafted products could be obtained. The mechanical behavior of the grafted films--especially in the water-swollen state--was examined and compared with that of the pure trunk polymer. In nearly all cases it was found that the tensile strength sigma B and the elongation at break epsilon R decreases as the grafting yield increases. Modification of GMA- and AAm-grafted films via chemical reactions was performed to create new functional groups of biomedical interest. In this manner a diol structure, a carboxylic acid structure, and a sulfonic acid group could be introduced in the grafted polymer. The water uptake of such modified films is increased markedly when compared with that of the unmodified samples

  10. Subepithelial connective tissue graft: a case report

    Directory of Open Access Journals (Sweden)

    Juliana Alcarás Saraiva

    2011-07-01

    Full Text Available Introduction and objective: Marginal tissue recession represents a common condition in Periodontology. Miller’s Classes I and II recessions, in which the etiological factors are well diagnosed and eliminated, show great predictability of total coverage when the technique of subepithelial connective tissue graft is used. This technique success has been mainly attributed to the double blood supply for graft’s nutrition, originating from the connective tissue of both the periosteum and flap. Case report and conclusion: The authors reported a clinical case in which a Miller’s Class I recession was treated by the surgical technique of subepithelial connective tissue graft, obtaining total coverage, eliminating the aesthetic deficiency and the dentin hypersensitivity complained by patient.

  11. Radiation-induced grafting of TMPM onto polypropylene

    International Nuclear Information System (INIS)

    The gamma radiation-induced graft copolymerization of 2,2,6,6-tetramethyl-4-piperidinyl-methacrylate (TMPM), a very effective hindered amine light stabilizer (HALS), onto polypropylene was investigated by simultaneous- irradiation technique. The various synthesis conditions on the graft content was studied. It was found that benzene, CCl4 and petroleum ether are more effective than other solvents, the percent grafting reached 7.1% for benzene. The percent grafting is higher when graft copolymerization is carried out in argon atmosphere than those in air. For all the grafting copolymerization carried out in benzene and CCl4, percent grafting increase linearly from 1 to 5 Mrad and beyond 5 Mrad, a tendency to level off appeared. At a constant dose, the percent grafting was found to be higher at high dose rate until 228 rad/s. Percent grafting also increased continuously with increasing monomer concentration up to 2.85 mol/L, but significant increase in grafting was observed only up to 1.14 mol/L

  12. Radiation initiated grafting onto fluoro polymers for membrane preparation

    Science.gov (United States)

    El-Assy, N. B.; Dessouki, A. M.

    The radiation initiating grafting of acrylamide (AAm) onto poly(tetrafluoroethylene/ hexafluoropropylene/vinylidene fluoride), TFB, films using the post-radiation grafting technique has been investigated. The factors affecting the grafting process such as radiation dose, dose rate, monomer concentration and temperature on the grafting yield were studied. It was found that the grafting yield is strongly dependent on the dose but independent on the dose rate. The dependence of the grafting rate on monomer concentration was found to be of 1.44 order. The results showed a steady increase of the initial grafting rate with temperature, whereas the final grafting yield passes a maximum around 45°C. The Arrhenius plot reveals two straight lines with different slope intersecting around 35°C. The overall activation energy for this grafting system was calculated and found to be 16.5 and 32.4 kcal/mol above and below 35°C, respectively. This behaviour is presumably correlated to a glass transition of the trunk polymer arising from amorphous material under restraint by crystallites. Some properties of the grafted films such a specific electric resistance, water uptake, mechanical properties and chemical and thermal stability were investigated. An improvement in these properties was observed which makes possible the use of these membranes in some practical applications.

  13. Insolubilisation of biologically active materials with novel radiation graft copolymers

    International Nuclear Information System (INIS)

    The use of radiation grafting to immobilise a typical enzyme, trypsin, is reported. The technique involves radiation grafting to a backbone polymer a monomer containing an appropriate functional group to which the enzyme is bonded. In the present work, p-nitrostyrene has been grafted to representative trunk polymers, polypropylene and PVC, the nitro group in the resulting copolymer converted to the isothiocyanato derivative to which trypsin is attached. Of importance to this insolubilisation process, especially for radiation sensitive backbone polymers, is the inclusion of additives which enhance grafting. A new class of additives which increase the grafting yields is reported using as representative backbone polymers, naturally occurring cellulose and synthetic low density polyethylene. The new additives are specific metal salts such as LiClO4. The reactivity of these salts in grafting enhancement has been compared with that of mineral acid which has previously been used as an additive to increase grafting yields in both preirradiation and simultaneous techniques. A new model for grafting enhancement in the presence of the metal salts as well as acids is proposed whereby increased grafting yields are attributed to increased partitioning of monomer into the graft region in the presence of ionic solutes. The value of these additives in preparing copolymers suitable for general reagent insolubilisation reactions is discussed

  14. Insolubilisation of biologically active materials with novel radiation graft copolymers

    Science.gov (United States)

    Garnett, J. L.; Jankiewicz, S. V.; Levot, R.; Sangster, D. F.

    The use of radiation grafting to immobilise a typical enzyme, trypsin, is reported. The technique involves radiation grafting to a backbone polymer a monomer containing an appropriate functional group to which the enzyme is bonded. In the present work, p-nitrostyrene has been grafted to representative trunk polymers, polypropylene and PVC, the nitro group in the resulting copolymer converted to the isothiocyanato derivative to which trypsin is attached. Of importance to this insolubilisation process, especially for radiation sensitive backbone polymers, is the inclusion of additives which enhance grafting. A new class of additives which increase the grafting yields is reported using as representative backbone polymers, naturally occurring cellulose and synthetic low density polyethylene. The new additives are specific metal salts such as LiClO 4. The reactivity of these salts in grafting enhancement has been compared with that of mineral acid which has previously been used as an additive to increase grafting yields in both preirradiation and simultaneous techniques. A new model for grafting enhancement in the presence of the metal salts as well as acids is proposed whereby increased grafting yields are attributed to increased partitioning of monomer into the graft region in the presence of ionic solutes. The value of these additives in preparing copolymers suitable for general reagent insolubilisation reactions is discussed.

  15. Dynamic, nondestructive imaging of a bioengineered vascular graft endothelium.

    Directory of Open Access Journals (Sweden)

    Bryce M Whited

    Full Text Available Bioengineering of vascular grafts holds great potential to address the shortcomings associated with autologous and conventional synthetic vascular grafts used for small diameter grafting procedures. Lumen endothelialization of bioengineered vascular grafts is essential to provide an antithrombogenic graft surface to ensure long-term patency after implantation. Conventional methods used to assess endothelialization in vitro typically involve periodic harvesting of the graft for histological sectioning and staining of the lumen. Endpoint testing methods such as these are effective but do not provide real-time information of endothelial cells in their intact microenvironment, rather only a single time point measurement of endothelium development. Therefore, nondestructive methods are needed to provide dynamic information of graft endothelialization and endothelium maturation in vitro. To address this need, we have developed a nondestructive fiber optic based (FOB imaging method that is capable of dynamic assessment of graft endothelialization without disturbing the graft housed in a bioreactor. In this study we demonstrate the capability of the FOB imaging method to quantify electrospun vascular graft endothelialization, EC detachment, and apoptosis in a nondestructive manner. The electrospun scaffold fiber diameter of the graft lumen was systematically varied and the FOB imaging system was used to noninvasively quantify the affect of topography on graft endothelialization over a 7-day period. Additionally, results demonstrated that the FOB imaging method had a greater imaging penetration depth than that of two-photon microscopy. This imaging method is a powerful tool to optimize vascular grafts and bioreactor conditions in vitro, and can be further adapted to monitor endothelium maturation and response to fluid flow bioreactor preconditioning.

  16. Surgical complications after renal transplantation in grafts with multiple arteries

    Directory of Open Access Journals (Sweden)

    Eduardo Mazzucchi

    2005-04-01

    Full Text Available INTRODUCTION: Renal transplantation with multiple arteries appears, in literature, associated to a major index of surgical complications. This study compared the surgical complications and short-term outcome renal transplants with multiple arteries and single artery grafts. MATERIALS AND METHODS: The data of 64 renal transplants with multiple arteries performed between January 1995 and December 1999 were compared to the ones of 292 transplants with single renal artery. The aspects analyzed were number of arteries of the graft, donor type, vascular reconstruction technique, the occurrence of surgical complications, the incidence of delayed graft function, graft function 1 month after transplantation, graft loss and the patients' deaths. RESULTS: The incidence of surgical complications in grafts with multiple arteries and single renal artery was respectively: vascular - 3.1% and 3.1%; urological - 6.3% and 2.7% and other surgical complications - 15.6% and 10.6%, respectively. The incidence of lymphoceles was 3.1% in grafts with a single artery and 12.5% in grafts with more than 1 artery (p = 0.0015. The incidence of delayed graft function in grafts with multiple arteries and with a single renal artery was respectively 35.1 and 29.1% (p = 0.295. Mean serum creatinine at the 30th postoperative day was 2.46 and 1.81 in grafts with multiple and with 1 artery, respectively (p=0.271. CONCLUSIONS: Kidney transplantation using grafts with single and multiple arteries present similar indexes of surgical complications and short-term outcome; lymphoceles were more frequent among grafts with multiple arteries.

  17. Hydrogen, a potential safeguard for graft-versus-host disease and graft ischemia-reperfusion injury?

    Science.gov (United States)

    Yuan, Lijuan; Shen, Jianliang

    2016-01-01

    Post-transplant complications such as graft-versus-host disease and graft ischemia-reperfusion injury are crucial challenges in transplantation. Hydrogen can act as a potential antioxidant, playing a preventive role against post-transplant complications in animal models of multiple organ transplantation. Herein, the authors review the current literature regarding the effects of hydrogen on graft ischemia-reperfusion injury and graft-versus-host disease. Existing data on the effects of hydrogen on ischemia-reperfusion injury related to organ transplantation are specifically reviewed and coupled with further suggestions for future work. The reviewed studies showed that hydrogen (inhaled or dissolved in saline) improved the outcomes of organ transplantation by decreasing oxidative stress and inflammation at both the transplanted organ and the systemic levels. In conclusion, a substantial body of experimental evidence suggests that hydrogen can significantly alleviate transplantation-related ischemia-reperfusion injury and have a therapeutic effect on graft-versus-host disease, mainly via inhibition of inflammatory cytokine secretion and reduction of oxidative stress through several underlying mechanisms. Further animal experiments and preliminary human clinical trials will lay the foundation for hydrogen use as a drug in the clinic.

  18. Mechanics of laser cut stent grafts

    Czech Academy of Sciences Publication Activity Database

    Major, Štěpán; Kocour, Vladimír; Hubálovský, Š.

    Prague: Institute of theoretical and applied mechanics, Academy of Sciences of the Czech Republic, v. v. i., 2015 - (Náprstek, J.; Fischer, C.), s. 186-187 ISBN 978-80-86246-42-0. ISSN 1805-8248. [Engineering mechanics 2015 /21./. Svratka (CZ), 11.05.2015-14.05.2015] Institutional support: RVO:68378297 Keywords : stent-grafts * nitinol * finite element analysis * fatigue * fracture Subject RIV: JJ - Other Materials

  19. LATE RENAL GRAFT REJECTION: PATHOLOGY AND PROGNOSIS

    Directory of Open Access Journals (Sweden)

    E.S. Stolyarevich

    2014-01-01

    Full Text Available Rejection has always been one of the most important cause of late renal graft dysfunction. Aim of the study was to analyze the prevalence of different clinico-pathological variants of rejection that cause late graft dysfunction, and evaluate their impact on long-term outcome. Materials and methods. This is a retrospective study that analyzed 294 needle core biopsy specimens from 265 renal transplant recipients with late (48,8 ± 46,1 months after transplantation allograft dysfunction caused by late acute rejection (LAR, n = 193 or chronic rejection (CR, n = 78 or both (n = 23. C4d staining was performed by immunofl uorescence (IF on frozen sections using a standard protocol. Results. Peritubular capillary C4d deposition was identifi ed in 36% samples with acute rejection and in 62% cases of chronic rejection (including 67% cases of transplant glomerulopathy, and 50% – of isolated chronic vasculopathy. 5-year graft survival for LAR vs CR vs their combination was 47, 13 and 25%, respectively. The outcome of C4d– LAR was (p < 0,01 better than of C4d+ acute rejection: at 60 months graft survival for diffuse C4d+ vs C4d− was 33% vs 53%, respectively. In cases of chronic rejection C4d+ vs C4d– it was not statistically signifi cant (34% vs 36%. Conclusion. In long-term allograft biopsy C4d positivity is more haracteristic for chronic rejection than for acute rejection. Only diffuse C4d staining affects the outcome. C4d– positivity is associated with worse allograft survival in cases of late acute rejection, but not in cases of chronic rejection. 

  20. Tissue Engineering: Creating Living Cardiovascular Grafts

    OpenAIRE

    Muylaert, D.E.P.

    2016-01-01

    When heart valves or coronary arteries fail, the surgical implantation of a replacement structure can be a life-saving operation. Right now, replacement vessels for bypass grafting are harvested from the leg or chest of the patient, which is an additional and invasive procedure. Similarly, heart valve prostheses are currently made out of non-living materials that do not grow along with patients, which is a particular disadvantage for pediatric patients. Immediately following implantation, the...

  1. Block and Graft Copolymers of Polyhydroxyalkanoates

    Science.gov (United States)

    Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

    2004-03-01

    Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

  2. Electron beam induced modification of grafted polyamides

    International Nuclear Information System (INIS)

    It is well known that irradiation, when applied on its own or in combination with other physical and chemical treatments, can manifest in radiation damage to materials. Radiation processing technology focuses upon producing favourable modification of materials through use of relatively high dose and dose rates. Current interest is in modifying the thermal and electrical properties of textured polymers in an effort to improve safety and wear comfort of clothing. No less important is the production of textiles which are safe to use, both in homes and offices. Present investigations provide additional data in support of findings which show that polyamides, a particular class of textured polymer, are amenable to radiation processing. Accelerated electron beam irradiation of sheets of polyamide fibre results in induced grafting of acrylic and methacrylic acids. The degree of grafting is critically dependent upon irradiation dose and the extent of monomers dilution. Of particular importance is the high correlation which is found between degree of grafting and a decrease in the softening rate of the modified polyamide. A systematic modification of electrical conductivity is also observed. (author)

  3. A Patient with Recurrent Arteriovenous Graft Thrombosis.

    Science.gov (United States)

    Allon, Michael

    2015-12-01

    Arteriovenous grafts (AVGs) are prone to frequent thrombosis that is superimposed on underlying hemodynamically significant stenosis, most commonly at the graft-vein anastomosis. There has been great interest in detecting AVG stenosis in a timely fashion and performing preemptive angioplasty, in the belief that this will prevent AVG thrombosis. Three surveillance methods (static dialysis venous pressure, flow monitoring, and duplex ultrasound) can detect AVG stenosis. Whereas observational studies have reported that surveillance with preemptive angioplasty substantially reduces AVG thrombosis, randomized clinical trials have failed to confirm such a benefit. There is a high frequency of early AVG restenosis after angioplasty caused by aggressive neointimal hyperplasia resulting from vascular injury. Stent grafts prevent AVG restenosis better than balloon angioplasty, but they do not prevent AVG thrombosis. Several pharmacologic interventions to prevent AVG failure have been evaluated in randomized clinical trials. Anticoagulation or aspirin plus clopidogrel do not prevent AVG thrombosis, but increase hemorrhagic events. Treatment of hyperhomocysteinemia does not prevent AVG thrombosis. Dipyridamole plus aspirin modestly decreases AVG stenosis or thrombosis. Fish oil substantially decreases the frequency of AVG stenosis and thrombosis. In patients who have exhausted all options for vascular access in the upper extremities, thigh AVGs are a superior option to tunneled internal jugular vein central vein catheters (CVCs). An immediate-use AVG is a reasonable option in patients with recurrent CVC dysfunction or infection. Tunneled femoral CVCs have much worse survival than internal jugular CVCs. PMID:25883073

  4. Grafting of protein-protein binding sites

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A strategy for grafting protein-protein binding sites is described. Firstly, key interaction residues at the interface of ligand protein to be grafted are identified and suitable positions in scaffold protein for grafting these key residues are sought. Secondly, the scaffold proteins are superposed onto the ligand protein based on the corresponding Ca and Cb atoms. The complementarity between the scaffold protein and the receptor protein is evaluated and only matches with high score are accepted. The relative position between scaffold and receptor proteins is adjusted so that the interface has a reasonable packing density. Then the scaffold protein is mutated to corresponding residues in ligand protein at each candidate position. And the residues having bad steric contacts with the receptor proteins, or buried charged residues not involved in the formation of any salt bridge are mutated. Finally, the mutated scaffold protein in complex with receptor protein is co-minimized by Charmm. In addition, we deduce a scoring function to evaluate the affinity between mutated scaffold protein and receptor protein by statistical analysis of rigid binding data sets.

  5. Patient's Perception About Coronary Artery Bypass Grafting

    Directory of Open Access Journals (Sweden)

    Kelminda Maria Bulhões Mendonça

    2015-10-01

    Full Text Available ABSTRACT OBJECTIVE: The diagnosis of coronary artery disease referred for heart surgery has an important psychological component. The purpose of this study was to access the difficulties experienced by individuals awaiting coronary artery bypass grafting and to determine strategies that facilitate adaptation to a new lifestyle, modified by the disease. METHODS: A qualitative, exploratory study involving patients admitted to a university teaching hospital in the city of Salvador, Bahia, Brazil, awaiting coronary artery bypass grafting. Semi-structured interviews were performed in accordance with a previously defined script based on the study objective. Each transcription was read in its entirety to verify the representativeness, homogeneity and pertinence of the data obtained (pre-analysis, followed by separation of categories of analysis. RESULTS: The descriptions of this study show that patients admitted to the completion of coronary artery bypass grafting experience a wide range of psychological difficulties, considering that surgery acquires interpretations that vary according to individuals' subjectivity. The patients recognized the benefit of being able to discuss their feelings as a means of diminishing their fear and anxiety. CONCLUSION: Helping patients find resources to confront more positively the daily hospitalization is an important aspect for the health care professionals who assist them. This goal can be achieved through modification of the biomedical model of care for a biopsychosocial view. The investment of time and attention is of fundamental importance and aims to overcome existing deficiencies that interfere with the outcome of patients after cardiac surgery.

  6. [Tissue grafts: an activity concerning many patients].

    Science.gov (United States)

    Loty, B

    1997-11-15

    Tissue allografts mainly include corneas, bone (and cartilage, tendon, ligament, aponevrosis), skin, vessels and cardiac valves. All these grafts have been widely used for many years and were the subject of a large number of experimental and clinical studies. The different steps allowing the obtention of different tissue allografts have in fact a common organization through tissue procurement and banking activities. Tissue banks have a central situation ensuring security, safety, traceability and distribution of tissues. Appropriate organization of the banks, and respect of high level standards are thus mandatory. Tissue transplantation activity in France has been studied through national surveys: they concern more than 600 hospitals and clinics, and grafts procured in France (excluding imported allografts) are around 15,000 a year. Precise regulation implied by the bioethical law published in 1994 and homogeneous organization of the activity allow the use of stringent and regularly updated standards, allowing the distribution to the patients of safe grafts procured in ethical conditions. The actual shortage of tissue allografts in France implies increasing procurement through a better organization of retrieval in hospitals and clinics and donation promotion. PMID:9501596

  7. Enhancing Osteochondral Allograft Viability: Effects of Storage Media Composition

    OpenAIRE

    Teng, Margie S.; Yuen, Audrey S.; Kim, Hubert T.

    2008-01-01

    Osteochondral allograft transplantation is a well-accepted treatment for articular cartilage damage. However, chondrocyte viability declines during graft storage, which may compromise graft performance. We first tested the hypothesis that the composition of commonly used storage media affects the viability of articular chondrocytes over time; we then tested the hypothesis that the addition of insulin growth factor-1 or the apoptosis inhibitor ZVAD-fmk could enhance the storage properties of s...

  8. Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

    Science.gov (United States)

    Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

    2015-01-01

    A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

  9. The Palatal Bone Block Graft for Onlay Grafting Combined with Maxillary Implant Placement: A Case Series.

    Science.gov (United States)

    Gluckman, Howard; Du Toit, Jonathan; Salama, Maurice

    2016-01-01

    The aim of this study was to introduce an intraoral bone block harvesting technique--the palatal bone block graft (PBBG)--as an alternative harvest site for autogenous bone blocks. The PBBG technique was used to onlay graft esthetic zone defects simultaneous to implant placement in five patients. Measurable objectives were used to evaluate outcomes, and treatment was reassessed at up to 6 years. Defects of the maxilla were successfully grafted with PBBG in all five cases, and tissues remained stable at 1- and 6-year follow-ups. Harvesting an autogenous bone block from the palate is an advantageous, predictable, and reproducible method for augmenting buccofacial defects at implant placement, and may be considered as an alternative to conventional intraoral bone block donor sites when treating the maxilla. PMID:27333009

  10. Fluorescence spectroscopy for assessment of liver transplantation grafts concerning graft viability and patient survival

    Science.gov (United States)

    Vollet Filho, José D.; da Silveira, Marina R.; Castro-e-Silva, Orlando; Bagnato, Vanderlei S.; Kurachi, Cristina

    2015-06-01

    Evaluating transplantation grafts at harvest is essential for its success. Laser-induced fluorescence spectroscopy (LIFS) can help monitoring changes in metabolic/structural conditions of tissue during transplantation. The aim of the present study is to correlate LIFSobtained spectra of human hepatic grafts during liver transplantation with post-operative patients' mortality rate and biochemical parameters, establishing a method to exclude nonviable grafts before implantation. Orthotopic liver transplantation, piggyback technique was performed in 15 patients. LIFS was performed under 408nm excitation. Collection was performed immediately after opening donor's abdominal cavity, after cold perfusion, end of back-table period, and 5 min and 1 h after warm perfusion at recipient. Fluorescence information was compared to lactate, creatinine, bilirubin and INR levels and to survival status. LIFS was sensitive to liver changes during transplantation stages. Study-in-progress; initial results indicate correlation between fluorescence and life/death status of patients.

  11. Impact of solvent selection on graft polymerization of acrylamide onto starch

    Science.gov (United States)

    The impact on polymer properties [molecular weight, monomer conversion, graft content, graft efficiency and anhydroglucose units between grafts (AGU/graft)] that result from changing the solvent for the graft co-polymerization of acrylamide onto starch from water to dimethylsulfoxide (DMSO) was eval...

  12. Radiation grafting of monomers on plastics and fibers

    International Nuclear Information System (INIS)

    The various methods for grafting monomers to a variety of backbone polymers utilizing ionizing radiation are briefly reviewed with emphasis on the most commonly used technique, namely, simultaneous grafting. The variables influencing the optimization of grafting are discussed. These include role of solvent, effects of temperature, radiation dose and dose rate, and homopolymer formation. Recent developments involving the use of novel additives in these reactions are also summarized. Additive effects discussed include the role of mineral acids, polyfunctional monomers, multifunctional acrylates, and inorganic salts. Mechanisms to explain effects of these additives are proposed. Applications of radiation grafting including potential commercial utilization are summarized. The significance of concurrent grafting in curing reactions, particularly with electron beam irradiation, is discussed, including the possible role of ionic intermediates in these reactions. Future trends in grafting are delineated. (orig.)

  13. Radiation grafting of styrene on starch with high efficiency

    Science.gov (United States)

    Sheikh, N.; Akhavan, A.; Ataeivarjovi, E.

    2013-04-01

    Wheat starch grafted with polystyrene (PS-g-starch) was synthesized via polymerization grafting of styrene on starch by gamma-ray. The effects of starch/styrene weight ratio, and amount of applied doses (5-40 kGy) on the percentage of grafting, G (%), were investigated. The results showed that G (%) increased with increasing starch content. The optimum condition, starch/styrene weight ratio 1/3 and the applied dose 10 kGy, led to 252.9% of grafting. The obtained graft copolymer was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, and scanning electron microscopy. FTIR spectroscopy as well as the XRD analysis exhibited the changes in chemical and crystalline structure of starch after grafting reaction. TGA demonstrated the changes in thermal stability of PS-g-starch copolymer. SEM micrographs indicated porous patches of PS adhering on the starch.

  14. Characterization of Grafted Polypropylene-Acrylamide Films for Dye Removal

    International Nuclear Information System (INIS)

    The graft copolymerization of Acrylamide onto polypropylene film using the direct gamma irradiation technique was studied. The factors affecting the grafting process such as type of solvent, inhibitor, radiation dose, and monomer concentration on the grafting yield were studied. It was found that the additions of 0.5 wt % , Mohr's salt reduced effectively the homo polymerization of acrylamide. The change in chemical structural of the pp-films due to grafting was investigated using IR, X-ray diffraction, thermal gravimeterical analysis, and scanning electron microscope (SEM). PP-g-p(AAm) films were allowed to react with two ionic dyes; organic reactive blue dye (Remazol Brilliant Bright Blue) and organic reactive red dye (Drimarene Scarlet K-2 G). The sshas been analyzed with visible spectrophotometry at 460 nm for dyed grafted film by red dye and at 490 nm for dyed grafted film by blue dye

  15. Graft-Derived Cell-Free DNA as a Marker of Transplant Graft Injury.

    Science.gov (United States)

    Oellerich, Michael; Walson, Philip D; Beck, Julia; Schmitz, Jessica; Kollmar, Otto; Schütz, Ekkehard

    2016-04-01

    Although short-term success after solid organ transplantation is good, long-term graft and recipient survival are both not satisfactory. Despite therapeutic drug monitoring (TDM) of immunosuppressive drugs (ISDs), both excessive and insufficient immunosuppression still do occur. There is a need for new biomarkers that, when combined with TDM, can be used to provide more effective and less toxic, personalized immunosuppression to improve long-term survival. Currently used methods are insufficient to rapidly, cost-effectively, and directly interrogate graft integrity after solid organ transplantation. However, because organ transplants are also genome transplants, measurement of graft-derived circulating cell-free DNA (GcfDNA) has shown promise as a way to improve both graft and recipient outcomes after solid organ transplantation through the early detection of severe graft injury, enabling an early intervention. A newly developed droplet digital polymerase chain reaction (ddPCR) method has advantages over expensive high-throughput sequencing methods to rapidly quantify GcfDNA percentages and absolute amounts. This procedure does not require donor DNA and therefore can be applied to any organ donor/recipient pair. The droplet digital polymerase chain reaction method allows for the early, sensitive, specific, and cost-effective direct assessment of graft integrity and can be used to define individual responses to ISDs including the minimal ISD exposures necessary to prevent rejection. This is especially important in patients undergoing ISD switches due to ISD toxicity, infections, or malignancies. Although prospective, multicenter clinical trials in liver, heart, and kidney transplantation have not been completed, early results suggest that GcfDNA can be combined with TDM to guide changes in immunosuppression to provide more effective, and less toxic treatment. Personalized immunosuppression will shift emphasis in transplantation from reaction to prevention and could

  16. Primary Graft Function, Metabolic Control, and Graft Survival After Islet Transplantation

    OpenAIRE

    Vantyghem, Marie-Christine; Kerr-Conte, Julie; Arnalsteen, Laurent; Sergent, Geraldine; Defrance, Frederique; Gmyr, Valery; Declerck, Nicole; Raverdy, Violeta; Vandewalle, Brigitte; Pigny, Pascal; Noel, Christian; Pattou, Francois

    2009-01-01

    OBJECTIVE To investigate the influence of primary graft function (PGF) on graft survival and metabolic control after islet transplantation with the Edmonton protocol. RESEARCH DESIGN AND METHODS A total of 14 consecutive patients with brittle type 1 diabetes were enrolled in this phase 2 study and received median 12,479 islet equivalents per kilogram of body weight (interquartile range 11,072–15,755) in two or three sequential infusions within 67 days (44–95). PGF was estimated 1 month after ...

  17. Plasma Induced Grafting of PSt onto Titanium Dioxide Powder

    International Nuclear Information System (INIS)

    An investigation of grafting of polymer of styrene (PSt) onto titanium dioxide powder is reported in this paper. The graft polymerization reaction was induced by N2 plasma treatment on the surface of titanium dioxide. Infrared (IR) spectra and X-ray photospectrum (XPS) results showed that PSt was grafted onto the titanium dioxide powder. An observation by X-ray diffraction (XRD) spectra indicated that the crystal structure of the titanium dioxide powder was unchanged after the plasma treatment

  18. Immunocytochemical features of obstructed saphenous vein coronary artery bypass grafts.

    OpenAIRE

    Brody, J I; Pickering, N J; Fink, G B

    1989-01-01

    The peroxidase-immunoperoxidase immunocytochemical method was used on 27 saphenous vein coronary artery bypass grafts, which had been resected because of recurrent angina, to identify in situ cellular and humoral elements possibly associated with graft occlusion. Immunostaining was performed on paraffin wax embedded control saphenous vein and graft sections incubated directly with primary antibodies against von Willebrand antigen (vWFAg), fibronectin, fibrinogen, leucocyte common antigen (LCA...

  19. Bone graft substitutes for spine fusion: A brief review

    OpenAIRE

    Gupta, Ashim; Kukkar, Nitin; Sharif, Kevin; Main, Benjamin J; Albers, Christine E; El-Amin III, Saadiq F

    2015-01-01

    Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been develo...

  20. The oriented graph of graftings in the Fuchsian case

    CERN Document Server

    Calsamiglia, Gabriel; Francaviglia, Stefano

    2012-01-01

    We prove the connectedness and calculate the diameter of the oriented graph of graftings associated to exotic complex projective structures on a compact surface S with a given holonomy representation of Fuchsian type. The oriented graph of graftings is the graph whose vertices are the equivalence classes of marked CP^1-structures on S with a given fixed holonomy, and there is an oriented edge between two structures if the second is obtained from the first by grafting.

  1. Radiation grafting of acrylic acid onto polypropylene films

    International Nuclear Information System (INIS)

    A study has been made for the preparation of membranes by the direct radiation grafting of acrylic acid (AAc) onto polypropylene (PP) films. The appropriate reaction conditions were selected under which the graft polymerization was carried out successfully. The effect of different solvents such as benzene, methanol/water mixture, isopropanol/water mixture, dimethyl formamide and distilled water on the swelling and grafting process of AAc onto PP films was investigated. In this grafting system ammonium ferrous sulphate (Mohr's salt) and ferric chloride were used as inhibitors to minimize the homopolymerisation of AAc and the suitable concentration of the inhibitor was found to be 1.0 and 1.5 wt% for Mohr's salt and ferric chloride, respectively. Also, the effect of monomer concentration on the rate of grafting was investigated. The dependence of the grafting rate on monomer concentration was found to be 1.1 order. This grafting system proceeded by diffusion controlled process. Some selected properties of the grafted films such as swelling behaviour, gel determination, mechanical and electrical properties were also investigated. It was found that the grafted membranes possess good hydrophilic properties which may make them promising in some practical applications. (author)

  2. Grafting polymerization of styrene onto preirradiated polypropylene fabric

    International Nuclear Information System (INIS)

    The grafting copolymerization of styrene onto polypropylene (PP) fabric has been studied by the preirradiation of gamma rays and electron beam, respectively. The PP fabric samples wee irradiated in the air and nitrogen gas individually. The effects of absorbed dose, styrene concentration in methanol, reaction temperature and reaction time on the degree of grafting were studied. Effects of storage time and temperature on the grafting rate were also observed. And a comparison of γ-ray and EB irradiation has been made. The results were reasonably interpreted by assuming that the grafting reaction was predominately initiated by trapped radicals

  3. Do Stem Cells Have an Effect When We Fat Graft?

    Science.gov (United States)

    Rinker, Brian D; Vyas, Krishna S

    2016-06-01

    Fat grafting has become a widely accepted modality of soft tissue restoration and has found applications in many areas of aesthetic and reconstructive plastic surgery. Numerous claims have been made regarding the regenerative effects of fat grafting on the recipient bed. The purpose of this paper is to survey the available literature to answer the question of whether fat grafting has a positive effect on the surrounding tissues. It has been convincingly demonstrated that fat grafts contain viable adipose-derived stem cells (ASCs). The fate of these cells is determined by the microenvironment of the recipient bed, but animal studies have shown that a large fraction of ASCs survive engraftment. Numerous clinical studies have demonstrated the positive effects of fat grafting on recipient tissues. Improvement in validated scar scores as well as scar stiffness measurements have been documented after fat grafting of burn scars. Fat grafting has also been convincingly demonstrated to improve the quality of irradiated tissues, as measured by validated clinical scales and staged histology. It is ultimately unclear whether ASCs are responsible for these effects, but the circumstantial evidence is weighty. Fat grafting is effective for volumizing and improving skin quality in the setting of radiation, burns, and other scars. The observed effects are likely due to ASCs, but the evidence does not support the routine use of ASC-enriched fat grafts. PMID:26545225

  4. Evaluation of different graft material in type 1 tympanoplasty

    OpenAIRE

    Kshitij Patil; Nitish Baisakhiya; Deshmukh, P. T.

    2014-01-01

    Aims and Objective: The present study was undertaken to compare the results of various autogeneous tissues temporalis fascia, tragal perichondrium, and fascia lata as graft materials for the type 1 tympanoplasty. Materials and Methods: A total of 120 cases with large, subtotal and total perforation were considered in the study. Of the 120 cases, temporalis fascia graft was used in 60 cases (Group-I), tragal perichondrium graft in 40 cases (Group-II), and fascia lata graft in 20 cases (Group-I...

  5. The Radiation Induced Graft Copolymerization of Methacrylic Acid to Nylon

    International Nuclear Information System (INIS)

    The grafting of methacrylic acid to nylon by the preirradiation technique has been studied. The rate of grafting is appreciably larger than that of homopolymerization. No simple relation exists between reaction rate and total dose. The temperature dependence of the rate of grafting to the fibre, preirradiated in air, indicates that initiation of grafting is likely to take place by decomposition of peroxide groups formed on irradiation. Electrical resistance measurements on the irradiated fibre indicate that this has been reduced by a factor of 10. (author)

  6. Target-like pigmentation after minipunch grafting in stable vitiligo

    Directory of Open Access Journals (Sweden)

    Nelee Bisen

    2014-01-01

    Full Text Available Surgical treatment for vitiligo has been ever evolving. Each surgical modality has its own benefits and limitations. Miniature punch grafting is the most extensively performed surgery, which gives good results in stable vitiligo. Herein we report an unusual type of repigmentation observed after minipunch grafting in a patient of stable vitiligo, which resembled target-like lesions with a "perigraft halo" surrounding individual grafts. Such pigment spread occurred despite the use of 0.5 mm larger graft from the donor site.

  7. pH responsive graft copolymers of chitosan.

    Science.gov (United States)

    Yilmaz, Elvan; Yalinca, Zulal; Yahya, Kovan; Sirotina, Uliana

    2016-09-01

    Grafting suitable polymers onto chitosan can produce cationic or polyampholyte polymers or hydrogels that are potential smart biomedical materials. Chitosan-graft-[poly(diethylamino)ethyl methacrylate] has been prepared in three different physical forms as linear free chains in solution, chemical gels crosslinked with glutaraldehyde, and poly(diethylamino)ethyl methacrylate] grafted onto chitosan tripolyphosphate gel beads. In addition to chemical structure, the graft copolymers were characterized with respect to their dissolution and swelling behavior in aqueous solution. It has been established that solubility of the products is controlled by the grafting yield. While pH sensitive polymers, which collapse at a given pH value are obtained at lower grafting yields, hydrogels form at higher grafting yields with pH responsive swelling behavior. Glutaraldehyde crosslinked chitosan-graft-[poly(diethylamino)ethyl methacrylate] gels and chitosan tripolyphosphate gel beads grafted with poly[(diethylamino)ethyl methacrylate] exhibit pH sensitive swelling with highest equilibrium swelling capacity at pH=1.2. PMID:26500176

  8. PDMS content affects in vitro hemocompatibility of synthetic vascular grafts.

    Science.gov (United States)

    Spiller, Dario; Losi, Paola; Briganti, Enrica; Sbrana, Silverio; Kull, Silvia; Martinelli, Ilaria; Soldani, Giorgio

    2007-06-01

    An unsolved problem when employing small-diameter vascular grafts for aorto-coronary by-pass and peripheral reconstruction is the early thrombotic occlusion. The PEtU-PDMS is a new elastomeric material, composed of poly(ether)urethane and polydimethylsiloxane, synthesized to realize grafts with improved hemocompatibility characteristics. In order to investigate the effect of PDMS content on hemocompatibility, three different percentages of PDMS containing grafts (10, 25 and 40) were evaluated. Grafts realized with Estane 5714-F1 and silicone medical grade tubes were used as references. The hemocompatibility was investigated by an in vitro circuit in which human anticoagulated blood was circulated into grafts by a peristaltic pump modified to obtain a passive flow. For each experiment, 40 cm length graft was closed into a circular loop and put in rotation for 2 h at 37 degrees C. At the end of the experiments different parameters regarding platelet adhesion and activation were evaluated: circulating platelets count, beta-thromboglobulin release, platelet CD62P expression and amount of monocyte-platelet conjugates. PEtU-PDMS grafts with 25 and 40% of PDMS induced the lowest platelet adhesion, plasma level of beta-TG and amount of monocyte-platelet conjugates. No significative variations were observed in CD62P expression. In conclusion, PDMS content significatively affects blood-graft surface interaction, in fact higher PDMS percentage containing grafts showed the best in vitro hemocompatibility. PMID:17268875

  9. An interesting grafting reactivity of EB preirradiated polypropylene film[Radiation grafting; Polypropylene; Free radical; peroxide; Acrylic acid; Acrylamide

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jie E-mail: chenjjd@online.sh.cn; Yang Liming; Chen Liqin; Wu Minhong; Nho, Y.C.; Kaetsua, Isao

    2004-02-01

    An interesting grafting reactivity of electron beam preirradiated polypropylene (PP) film was found by grafting of acrylic acid (AAc) and acrylamide (AAm) repeatedly or intermittently. The preirradiated PP film could be grafted several times intermittently and the free radicals or peroxides on the samples could be determined after several times grafting reaction. The effects of storage time, reaction time and repeated reaction times on the degree of grafting were investigated. The trapped radicals, peroxy-radicals and peroxides on the preirradiated and reacted PP films were determined by using electron spin resonance (ESR) and 1,1-diphenyl-2-picryl hydrazyl (DPPH), respectively. An interpenetrating polymer networks (IPN) with both temperature and pH sensitive properties was obtained by two times grafting of AAm and AAc onto preirradiated PP film.

  10. MRI of double-bundle ACL reconstruction: evaluation of graft findings

    International Nuclear Information System (INIS)

    To demonstrate the magnetic resonance imaging (MRI) findings of double-bundle (DB) anterior cruciate ligament (ACL) reconstruction grafts. Sixty-six patients with DB ACL reconstruction were evaluated with MRI 2 years postoperatively. Graft thickness was measured separately by two musculoskeletal radiologists. The MRI findings of graft disruption, signal intensity (SI) changes, cystic degeneration, arthrofibrosis, and impingement were analyzed. The statistical significance of the association between MRI findings was calculated. The mean anteromedial (AM) graft thickness was reduced 9% and the mean posterolateral (PL) graft thickness was reduced 18% from the original graft thickness. Disruption was seen in 3% of AM grafts and 6% of PL grafts and a partial tear in 8 and 23%, respectively. Both grafts were disrupted in 3% of patients. Increased SI was seen in 14% of intact AM grafts and in 60% of partially torn AM grafts (p = 0.032). In PL grafts the increased SI was seen in 51% of the intact grafts and in 93% of the partially torn grafts (p = 0.005). Cystic degeneration was seen in 8% of AM grafts and in 5% of PL grafts. Diffuse arthrofibrosis was seen in 5% of patients and a localized cyclops lesion in 3% of patients. Impingement of the AM graft was seen in 8% of patients. Both grafts were disrupted in 3% of patients. Also, the frequencies of other complications were low. The use of orthogonal sequences in the evaluation of the PL graft SI seems to cause volume-averaging artefacts. (orig.)

  11. MRI of double-bundle ACL reconstruction: evaluation of graft findings

    Energy Technology Data Exchange (ETDEWEB)

    Kiekara, Tommi; Paakkala, Antti [Tampere University Hospital, Medical Imaging Centre, Tampere (Finland); Jaervelae, Timo [Sports Clinic and Hospital Mehilaeinen, Tampere (Finland); Huhtala, Heini [University of Tampere, School of Health Sciences, Tampere (Finland)

    2012-07-15

    To demonstrate the magnetic resonance imaging (MRI) findings of double-bundle (DB) anterior cruciate ligament (ACL) reconstruction grafts. Sixty-six patients with DB ACL reconstruction were evaluated with MRI 2 years postoperatively. Graft thickness was measured separately by two musculoskeletal radiologists. The MRI findings of graft disruption, signal intensity (SI) changes, cystic degeneration, arthrofibrosis, and impingement were analyzed. The statistical significance of the association between MRI findings was calculated. The mean anteromedial (AM) graft thickness was reduced 9% and the mean posterolateral (PL) graft thickness was reduced 18% from the original graft thickness. Disruption was seen in 3% of AM grafts and 6% of PL grafts and a partial tear in 8 and 23%, respectively. Both grafts were disrupted in 3% of patients. Increased SI was seen in 14% of intact AM grafts and in 60% of partially torn AM grafts (p = 0.032). In PL grafts the increased SI was seen in 51% of the intact grafts and in 93% of the partially torn grafts (p = 0.005). Cystic degeneration was seen in 8% of AM grafts and in 5% of PL grafts. Diffuse arthrofibrosis was seen in 5% of patients and a localized cyclops lesion in 3% of patients. Impingement of the AM graft was seen in 8% of patients. Both grafts were disrupted in 3% of patients. Also, the frequencies of other complications were low. The use of orthogonal sequences in the evaluation of the PL graft SI seems to cause volume-averaging artefacts. (orig.)

  12. Osseous scintigraphy and auxiliary graft. Scintigraphie osseuse et greffe d'appoint

    Energy Technology Data Exchange (ETDEWEB)

    Khelifa, F.; Siles, S. (Hopital de la Timone, 13 - Marseille (France)); Puech, B.

    1992-12-01

    The scintigraphy could be a good way to survey the osseous graft: three cases are studied in which were recognized the presence of a graft, surinfection, graft lysis, pseudo-arthrosis, algodystrophy. 8 refs., 5 figs.

  13. PVDF multifilament yarns grafted with polystyrene induced by γ-irradition: Influence of the grafting parameters on the mechanical properties

    Science.gov (United States)

    Marmey, P.; Porté, M. C.; Baquey, Ch.

    2003-08-01

    The development of alternative prosthetic materials for cardiovascular applications has found growing interest due to the failure to date to be able to implement functional patent small diameter vascular grafts (∅Biomed. Eng. 7 (1979) 429]. A four step method is necessary to achieve this "heparin-like" surface transformation [J. Biomed. Mater. Res. 52 (2000) 119]. The first step consists in grafting polystyrene onto the PVDF surface by γ irradiation. The purpose of this study was to evaluate the influence of grafting parameters on the mechanical properties: (i) γ-ray irradiation time and (ii) grafting time of styrene monomers, which polymerize and form polystyrene bound to the PVDF surface.

  14. Angiographic Evaluation of Carotid Artery Grafting with Prefabricated Small-Diameter, Small-Intestinal Submucosa Grafts in Sheep

    International Nuclear Information System (INIS)

    The purpose of this study was to report the longitudinal angiographic evaluation of prefabricated lyophilized small-intestinal submucosa (SIS) grafts placed in ovine carotid arteries and to demonstrate a variety of complications that developed. A total of 24 grafts, 10 cm long and 6 mm in diameter, were placed surgically as interposition grafts. Graft patency at 1 week was evaluated by Doppler ultrasound, and angiography was used for follow-up at 1 month and at 3 to 4 months. A 90% patency rate was found at 1 week, 65% at 1 month, and 30% at 3 to 4 months. On the patent grafts, angiography demonstrated a variety of changes, such as anastomotic stenoses, graft diffuse dilations and dissections, and aneurysm formation. These findings have not been previously demonstrated angiographically by other investigators reporting results with small-diameter vessel grafts made from fresh small-intestinal submucosa (SIS). The complications found were partially related to the graft construction from four SIS layers. Detailed longitudinal angiographic study should become an essential part of any future evaluation of small-vessel SIS grafting.

  15. Dilatation of Stent-Grafts by Luminal Pressures: Experimental Evaluation of Polytetrafluoroethylene (PTFE) and Woven Polyester Grafts

    International Nuclear Information System (INIS)

    Purpose: To evaluate the effect on dilatation of three types of covering materials used for endovascular stent-grafts.Methods: Stent-grafts with three types of covering material [0.1-mm polytetrafluoroethylene (PTFE), 0.2-mm PTFE, and 0.15-mm woven polyester] were placed in a fluid circuit. For the pulsatile pressure test, the luminal pressure of 190/130 mmHg was loaded up to 300,000 pulses. For the static pressure test, the luminal pressure was increased from 50 to 300 mmHg at 50-mmHg increments. The percent of dilatation of each stent-graft was compared.Results: The 0.1-mm PTFE stent-graft was significantly more dilated than the 0.2-mm PTFE and the 0.15-mm woven polyester stent-graft (p < 0.005) in both examinations. There was no significant difference between the 0.2-mm PTFE and the 0.15-mm woven polyester stent-grafts. The dilatation of the 0.1-mm PTFE stent-graft was irreversible.Conclusion: The 0.15-mm woven polyester and the 0.2-mm PTFE stent-grafts may be preferable to the 0.1-mm PTFE stent-graft with regard to dilatation and deformity

  16. Impact of bone graft harvesting techniques on bone formation and graft resorption

    DEFF Research Database (Denmark)

    Saulacic, Nikola; Bosshardt, Dieter D; Jensen, Simon S;

    2015-01-01

    BACKGROUND: Harvesting techniques can affect cellular parameters of autogenous bone grafts in vitro. Whether these differences translate to in vivo bone formation, however, remains unknown. OBJECTIVE: The purpose of this study was to assess the impact of different harvesting techniques on bone fo...

  17. Synthesis and characterization of polyvinylimidazole-grafted superparamagnetic iron oxide nanoparticles (Si-PVIm-grafted SPION)

    International Nuclear Information System (INIS)

    Polyvinylimidazole (PVIm)-grafted superparamagnetic iron oxide nanoparticles (SPION) (Si-PVIm-grafted Fe3O4 NPs) were prepared by grafting of telomere of PVIm on the SPION. The product identified as magnetite, which has an average crystallite size of 9 ± 2 nm as estimated from X-ray line profile fitting. Particle size was estimated as 10.0 ± 0.5 nm from TEM micrographs. Mean particle size is found as 8.4 ± 1.0 nm which agrees well with the values calculated from XRD patterns (9 ± 2 nm). Vibrating Sample Magnetometer (VSM) analysis explained the superparamagnetic nature of the nanocomposite. Thermogravimetric analysis showed that the Si-Imi is 25 % of the Si-PVIm-grafted SPION, which means an inorganic content is about 75 %. Detailed electrical and dielectric properties of the properties of the product are also presented. The conductivity of the sample increases significantly with temperature and has the value in the range of 1.14 × 10−7–1.78 × 10−4 S cm−1. Analysis of the real and imaginary parts of the permittivities indicated temperature and frequency dependency representing interfacial polarization and temperature-assisted reorganization effects.

  18. Study of the conformational behavior of graft copolymers by chromatography with solvents selective for grafts

    Czech Academy of Sciences Publication Activity Database

    Netopilík, Miloš; Janata, Miroslav; Svitáková, Romana; Trhlíková, Olga; Berek, D.; Macova, E.; Limpouchová, Z.; Procházka, K.

    Prague: Organic, Bioorganic and Pharmaceutical Chemistry Branch of the Czech Chemical Society, 2015. s. 147. [Advances in Organic, Bioorganic and Pharmaceutical Chemistry /50./ - "Liblice 2015". 06.11.2015-08.11.2015, Olomouc] R&D Projects: GA ČR(CZ) GA13-02938S Institutional support: RVO:61389013 Keywords : graft copolymer * SEC * light scattering Subject RIV: CD - Macromolecular Chemistry

  19. Synthesis and characterization of polyvinylimidazole-grafted superparamagnetic iron oxide nanoparticles (Si-PVIm-grafted SPION)

    Energy Technology Data Exchange (ETDEWEB)

    Erdemi, H. [Yalova University, Department of Polymer Engineering (Turkey); Soezeri, H. [TUBITAK-UME, National Metrology Institute (Turkey); Senel, M.; Baykal, A., E-mail: hbaykal@fatih.edu.tr [Fatih University, Department of Chemistry, Faculty of Arts and Sciences (Turkey)

    2012-08-15

    Polyvinylimidazole (PVIm)-grafted superparamagnetic iron oxide nanoparticles (SPION) (Si-PVIm-grafted Fe{sub 3}O{sub 4} NPs) were prepared by grafting of telomere of PVIm on the SPION. The product identified as magnetite, which has an average crystallite size of 9 {+-} 2 nm as estimated from X-ray line profile fitting. Particle size was estimated as 10.0 {+-} 0.5 nm from TEM micrographs. Mean particle size is found as 8.4 {+-} 1.0 nm which agrees well with the values calculated from XRD patterns (9 {+-} 2 nm). Vibrating Sample Magnetometer (VSM) analysis explained the superparamagnetic nature of the nanocomposite. Thermogravimetric analysis showed that the Si-Imi is 25 % of the Si-PVIm-grafted SPION, which means an inorganic content is about 75 %. Detailed electrical and dielectric properties of the properties of the product are also presented. The conductivity of the sample increases significantly with temperature and has the value in the range of 1.14 Multiplication-Sign 10{sup -7}-1.78 Multiplication-Sign 10{sup -4} S cm{sup -1}. Analysis of the real and imaginary parts of the permittivities indicated temperature and frequency dependency representing interfacial polarization and temperature-assisted reorganization effects.

  20. Insitu grafting silica nanoparticles reinforced nanocomposite hydrogels

    Science.gov (United States)

    Yang, Jun; Han, Chun-Rui; Duan, Jiu-Fang; Xu, Feng; Sun, Run-Cang

    2013-10-01

    Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties.Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties. Electronic supplementary information (ESI) available: FTIR spectra of SNP after silane treatment, dynamic oscillatory shear measurements as a function of frequency, constrained polymer chain analysis by a change in the peak height in loss factor spectra, molecular weight of grafted chains at different stages of gelation, prediction of the SNP reinforcing mechanism in the

  1. Perfluorinated polymer grafting: influence of preirradiation conditions

    International Nuclear Information System (INIS)

    The technological interest of perfluorinated polymers is related to its specific properties like low chemical reactivity and high mechanical and temperature resistance. The development of polymeric membranes for PEM fuel cell dispositives requires beyond these characteristics, a long-life time performance and low cost compared to Nafion membranes. By these material have high crystallinity, the radiation grafting indeed occurs but this process generate a low mechanical resistance aggregate. In this way, it is necessary to render the polymer with a low crystallinity or even amorphous. Generally, irradiation under polymer melt temperatures makes the crystallinity breaking and polymer crosslinking. The main objective of this work was promoting the crosslinking process into perfluorinated polymers by pre-irradiation method and to precede styrene grafting by electron beam irradiation in a second step. The experimental methodology consists in pre-irradiate perfluorinated polymers films like PTFE and PFA under high temperature (> 300 deg C) and vacuum conditions by electron beam irradiation at 5 kGy to 30 kGy doses and 2,85 kGy/s to 22,4 kGy/s dose rates. To obtain temperatures above 300 deg C, it was necessary construct a vacuum chamber with a heating system where temperature process could be follow up in real time. Some molecular alterations in polymeric matrix were analyzed by Mid-ATR-FTIR spectroscopy; macroscopic changes are verified by gravimetry. The styrene grafting onto these samples is realized by electron beam irradiation at doses between 30 and 100 kGy. These results are discussed. (author)

  2. Reshaping Human Antibodies: Grafting an Antilysozyme Activity

    Science.gov (United States)

    Verhoeyen, Martine; Milstein, Cesar; Winter, Greg

    1988-03-01

    The production of therapeutic human monoclonal antibodies by hybridoma technology has proved difficult, and this has prompted the ``humanizing'' of mouse monoclonal antibodies by recombinant DNA techniques. It was shown previously that the binding site for a small hapten could be grafted from the heavy-chain variable domain of a mouse antibody to that of a human myeloma protein by transplanting the hypervariable loops. It is now shown that a large binding site for a protein antigen (lysozyme) can also be transplanted from mouse to human heavy chain. The success of such constructions may be facilitated by an induced-fit mechanism.

  3. Grafting of Porous Polymers for Biological Applications

    International Nuclear Information System (INIS)

    Research on application of radiation processing to polymers is mainly focused by the National Atomic Commission (CNEA). The Agricultural and Industrial Applications Laboratory Unit operates at the Ezeiza Atomic Center since the end of 1980s. Since 1997 a new research group headed by Dr. O. Cascone and Dr. M. Grasselli, devoted to downstream processing of proteins from the University of Buenos Aires, was involved in the implementation of grafting techniques in collaboration with Dr. E. Smolko from CNEA. In 1999 Dr. M. Grasselli moved to the Universidad Nacional de Quilmes where he continued working on application of gamma radiation to materials for biotechnological process. (author)

  4. Thermal behaviors and grafting process of LDH/benzene derivative hybrid systems

    International Nuclear Information System (INIS)

    Highlights: ► Orientation of the organic entities between the layers of the mineral network. ► Influence of the organics functional group on the stability of the hybrid material. ► Demonstration of three different behaviors in terms of the grafting process. - Abstract: Thermal behaviors of four hybrid layered double hydroxide (LDH) phases have been studied by thermogravimetric analyses coupled with mass spectroscopy, temperature dependence of X-ray powder diffraction measurements, and temperature dependence of infrared spectroscopy measurements. Inorganic zinc–aluminium LDH main layers (with a Zn2+/Al3+ cationic ratio of 2) inserted the following four organic anions: benzene carboxylate, 4-hydroxy-benzene carboxylate, benzene sulfonate and 4-hydroxy-benzene sulfonate. The four LDH hybrids have been synthesized by the coprecipitation method. The as-prepared samples have been characterized and their compositions were determined. Thermal evolution of the crystalline phases during the dehydration (occurring before 200 °C) and the dehydroxylation (occurring between 200 and 300 °C) gave evidence for organic anion grafting onto the inorganic main layer. The thermal stability of the LDH hybrid system depends on the nature of the intercalated aromatic anion. The thermal grafting process can be monitored, as well as its thermal reversibility, by choosing the functionalizations of the benzenic anion and the temperature of the applied heat treatment.

  5. Grafting of ionic liquids on stainless steel surface for antibacterial application.

    Science.gov (United States)

    Pang, Li Qing; Zhong, Li Juan; Zhou, Hui Fang; Wu, Xue E; Chen, Xiao Dong

    2015-02-01

    Stainless steel (SS) is favored for many uses due to its excellent chemical resistance, thermal stability and mechanical properties. Biofilms can be formed on stainless steel and may lead to serious hygiene problems and economic losses in many areas, e.g. food processing, public infrastructure and healthcare. For the first time, our work endeavored to make SS having antibacterial properties, ionic liquids (ILs) were grafted on SS surface via silane treatment followed by thiol-ene click reaction. The chemical structure and composition of the ILs grafted stainless-steel coupon surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The antibacterial activity has been investigated, and the results showed that the ILs grafted SS surface exhibited significant antibacterial effects against Gram-negative Escherichia coli. Additionally, the results obtained here indicated that the ILs used here having bromide anion showed much better antibacterial activity against E. coli than the corresponding ILs with tetrafluoroborate and hexafluorophosphate as anions. These results obtained here can help to design novel and more efficient stainless steel having antibacterial surface. PMID:25561415

  6. Preparation and biocompatibility of grafted functional β-cyclodextrin copolymers from the surface of PET films.

    Science.gov (United States)

    Jiang, Yan; Liang, Yuan; Zhang, Hongwen; Zhang, Weiwei; Tu, Shanshan

    2014-08-01

    The hydrophobic inert surface of poly(ethylene terephthalate) (PET) film has limited its practical bioapplications, in which case, better biocompatibility should be achieved by surface modification. In this work, the copolymer of functional β-cyclodextrin derivatives and styrene grafted surfaces was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized PET. The structures, composition, properties, and surface morphology of the modified PET films were characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by a thick targeted copolymer layer, and the hydrophobic surface of PET was changed into an amphiphilic surface. The copolymer-grafted surfaces were also shown good biocompatibility on which SGC-7901 A549 and A549/DDP cells readily attached and proliferated, demonstrating that the functional copolymer-grafted PET films could be a promising alternative to biomaterials especially for tissue engineering. PMID:24907730

  7. Diffusivities, viscosities, and conductivities of solvent-free ionically grafted nanoparticles

    KAUST Repository

    Hong, Bingbing

    2013-01-01

    A new class of conductive composite materials, solvent-free ionically grafted nanoparticles, were modeled by coarse-grained molecular dynamics methods. The grafted oligomeric counterions were observed to migrate between different cores, contributing to the unique properties of the materials. We investigated the dynamics by analyzing the dependence on temperature and structural parameters of the transport properties (self-diffusion coefficients, viscosities and conductivities) and counterion migration kinetics. Temperature dependence of all properties follows the Arrhenius equation, but chain length and grafting density have distinct effects on different properties. In particular, structural effects on the diffusion coefficients are described by the Rouse model and the theory of nanoparticles diffusing in polymer solutions, viscosities are strongly influenced by clustering of cores, and conductivities are dominated by the motions of oligomeric counterions. We analyzed the migration kinetics of oligomeric counterions in a manner analogous to unimer exchange between micellar aggregates. The counterion migrations follow the "double-core" mechanism and are kinetically controlled by neighboring-core collisions. © 2013 The Royal Society of Chemistry.

  8. Controlling Free Volume for Permeability enhancement in Polymer-Grafted Nanocomposites

    Science.gov (United States)

    Bilchak, Connor; Buenning, Eileen; Kumar, Sanat; Durning, Christopher; Benicewicz, Brian

    Significant advances in polymer membrane technology have been made by exploring glassy materials with intrinsically high `free volume', allowing for diffusion selectivity. However, the permeability of these materials is restricted by the Robeson Upper Bound and exhibits long-term aging. While nanofiller have been used to avoid the deleterious effect of aging, they further limit transport properties and can result in non-equilibrium structures that phase-separate. We here show that 14nm silica nanoparticles grafted with rubbery Poly(Methyl Acrylate) (PMA) chains form hexatic lattices, solving a common difficulty in this class of membrane constructs of controlled dispersion morphology. In addition, our results show that these materials have permeabilities elevated relative to the neat polymer matrix, offering surprising beneficial gas transport properties. We also show that the `free volume' available for diffusion can be adequately controlled by tuning polymer chain length and graft density. We propose the morphology of these grafted nanoparticle systems may be manipulated to optimize these composites for a wide variety of vital gas separations.

  9. Effect of 60Co radiation-induced grafting of methyl methacrylate on mechanical properties of bamboo

    International Nuclear Information System (INIS)

    In order to investigate the effect of radiation grafting on mechanical properties of bamboo, the original and carbonized bamboo soaked with monomer MMA were radiation grafted by 60Co γ rays with the doses of 60-220 kGy. The results showed that compared with original blanks, treated with MMA and irradiated with the dose of 180 kGy the specific gravity, bending strength modulus of elasticity of original bamboo increased by 6.7%, 4.4%, and 28%, meanwhile its oven-dried radial, tangential and volumetric shrinkage decreased by 38.9%, 47.4%, and 32.9%, respectively. What is more, treated with MMA and irradiated with the doses of 140 kGy the specific gravity and modulus of elasticity of carbonized bamboo increased by 6.8% and 20%, while its oven-dried radial, tangential, volumetric shrinkage decreased by 11%, 4.6% and 12%, respectively. The study reveals that mechanical properties of original and carbonized bamboo can be enhanced by radiation grafting copolymerization with suitable absorbed doses, which may be valuable for the further research of developing new bamboo plastic composites. (authors)

  10. Extraction, characterization of components, and potential thermoplastic applications of camelina meal grafted with vinyl monomers.

    Science.gov (United States)

    Reddy, Narendra; Jin, Enqi; Chen, Lihong; Jiang, Xue; Yang, Yiqi

    2012-05-16

    Camelina meal contains oil, proteins, and carbohydrates that can be used to develop value-added bioproducts. In addition to containing valuable polymers, coproducts generated during the production of biofuels are inexpensive and renewable. Camelina is a preferred oilseed crop for biodiesel production because camelina is easier to grow and provides better yields. In this research, the components in camelina meal were extracted and studied for their composition, structure, and properties. The potential of using the camelina meal to develop thermoplastics was also studied by grafting various vinyl monomers. Oil (19%) extracted from camelina meal could be useful for food and fuel applications, and proteins and cellulose in camelina meal could be useful in the development of films, fibers, and thermoplastics. Thermoplastic films developed from grafted camelina meal had excellent wet tensile properties, unlike thermoplastics developed from other biopolymers. Camelina meal grafted with butylmethacrylate (BMA) had high dry and wet tensile strengths of 53.7 and 17.3 MPa, respectively. PMID:22540881

  11. Correlation between Density and Resorption of Fresh-Frozen and Autogenous Bone Grafts

    OpenAIRE

    2014-01-01

    Trial Design. This analysis compared the outcome of fresh-frozen versus autologous bone block grafts for horizontal ridge augmentation in patients with Cawood and Howell class IV atrophies. Methods. Seventeen patients received autologous grafts and 21 patients received fresh-frozen bone grafts. Patients underwent CT scans 1 week and 6 months after surgery for graft volume and density analysis. Results. Two autologous and 3 fresh-frozen grafts failed. Autologous and fresh-frozen grafts lost, r...

  12. Radiation grafting polymerization of N,N-dimethyl acrylamide on polypropylene

    International Nuclear Information System (INIS)

    The radiation grafting of N,N-dimethlacrylamide (DMAA) on polypropylene (PP) films was investigated by the following three methods. In the mutual grafting, the effect of solvents on the grafting was notable. The grafting did not occur in the aqueous solution of DMAA due to the formation of insoluble homopolymers. The suitable solvent for the grafting was benzene. The maximum grafting occurred in 45 - 65% monomer concentration. In the grafting on peroxidized PP, the effect of solvents on the grafting was notable. The grafting did not occur in the aqueous solution of DMAA due to the formation of insoluble homopolymers. The suitable solvent for the grafting was benzene. The extent of grafting increased with increasing DMAA content. The graft polymerization was induced above 50 deg C, and increased with the rist of reaction temperature. In the grafting by trapped radicals, the graft polymerization was induced even at 0 deg C. The conversion of DMAA homopolymer was very small, and the extent of grafting was larger than that obtained by two methods mentioned above. The PP films on which more than 500 % of DMAA was grafted were easily obtained. It is important for the grafting to suppress the formation of DMAA homopolymer outside PP films, and to diffuse monomer into PP films. The graft polymerization was induced only in the amorphous region of PP films. (Kako, I.)

  13. EVALUATION OF PAL ACTIVITY, PHENOLIC AND FLAVONOID CONTENTS IN THREE PISTACHIO ( PISTACIA VERA L.) CULTIVARS GRAFTED ONTO THREE DIFFERENT ROOTSTOCKS

    OpenAIRE

    N. Nadernejad; Ahmadimoghadam, A.; J. Hossyinifard; S. Poorseyedi

    2013-01-01

    Phenylalanine ammonia lyase (PAL) is a biochemical marker of the environmental stress and plays a pivotal role in phenolic synthesis. The lower ROS level and oxidative damage was observed in grafted plants and the rootstocks have a profound influence on the biochemical composition, especially phenolic compounds. Regarding the importance of the effect rootstocks have on scion in pistachio trees, this study was carried out to assess and compare three pistachio cultivars ("Ahmadaghaii", "Ohadi" ...

  14. Polymer electrolyte membranes for fuel cells by radiation induced grafting with electron beam irradiation: state-of-the-art

    International Nuclear Information System (INIS)

    Polymer electrolyte membranes have generated considerable interest in various fields of industrial interest due to their wide spread applications in fuel cells, batteries, electrolyzers sensors and actuators. Such diversity in applications implies a strong demand to architect the membranes towards particular properties for specific applications. Radiation induced grafting of vinyl and acrylic monomers into polymeric films, is an appealing method for producing various polymer electrolyte membranes. This method has the advantages of simplicity, controllability over the composition leading to tailored membrane properties and absence of shaping problem as preparation starts with substrate in a film form. It also has the flexibility of using various types of radiation sources such as gamma-rays and electron beam. Of all, electron beam (EB) accelerator is an advantageous source of high energy radiation that can initiate grafting reactions required for preparation of the membranes particularly when pilot scale production and commercial applications are sought. The grafting penetration can be varied from surface to bulk of membranes depending on the acceleration energy. This lecture reviews the-state of- the-art in the use of EB irradiation in preparation of composite and grafted polymer electrolyte membranes for fuel cell applications by radiation induced grafting with simultaneous irradiation and preirradiation methods. The use of simultaneous EB irradiation method was found to simplify the process and reduce the reaction time as well as the monomer consumption whereas the use of preirradiation method in a single-step route provides a shorter route to prepare polymer electrolyte membranes with improved properties and reduced cost in addition of setting basis for designing a continuous line to produce these membranes with dedicated EB facilities

  15. Preimplantation biopsy predicts delayed graft function, glomerular filtration rate and long-term graft survival of transplanted kidneys

    Directory of Open Access Journals (Sweden)

    José A. Pedroso

    2016-01-01

    Full Text Available The predictive value of preimplantation biopsies for long-term graft function is often limited by conflicting results. The aim of this study was to evaluate the influence of time-zero graft biopsy histological scores on early and late graft function, graft survival and patient survival, at different time points. We retrospectively analyzed 284 preimplantation biopsies at a single center, in a cohort of recipients with grafts from live and deceased donors (standard and nonstandard, and their impact in posttransplant renal function after a mean follow-up of 7 years (range 1-16. Implantation biopsy score (IBS, a combination score derived from 4 histopathological aspects, was determined from each sample. The correlation with incidence of delayed graft function (DGF, creatinine clearance (1st, 3rd and 5th posttransplant year and graft and patient survival at 1 and 5 years were evaluated. Preimplantation biopsies provided somewhat of a prognostic index of early function and outcome of the transplanted kidney in the short and long term. In the immediate posttransplantation period, the degree of arteriolosclerosis and interstitial fibrosis correlated better with the presence of DGF. IBS values between 4 and 6 were predictive of worst renal function at 1st and 3rd years posttransplant and 5-year graft survival. The most important histological finding, in effectively transplanted grafts, was the grade of interstitial fibrosis. Patient survival was not influenced by IBS. Higher preimplantation biopsy scores predicted an increased risk of early graft losses, especially primary nonfunction. Graft survival (at 1st and 5th years after transplant but not patient survival was predicted by IBS.

  16. Characterization of Functionalized Acrylic acid /4- Vinyl Pyridine Graft Copolymers

    International Nuclear Information System (INIS)

    Properties and characterization of the membranes prepared by radiation grafting of acrylic acid (AAc) or/ and 4-vinyl pyridine (4VP) onto low density polyethylene (LDPE) and polypropylene (PP) films were carried out. The FTIR spectra for the grafted membranes were studied to evaluate the structure change as a result of grafting. The swelling behaviour of the graft copolymer in methanol was studied. It was found that the grafting of AAc and/ or 4- VP onto LDPE and PP resulted in introducing good hydrophilic properties to such polymer substrates. The hydrophilic properties were directly proportional to the amount of functional groups. The mechanical properties (Young's modulus, elongation percent and tensile strength) of the grafted membranes also, have been investigated. As the grafting degree increases, the modulus also increases. Increasing the hydrophilicity of the membranes by chemical treatment enhances its mechanical properties. The thermal parameters of the grafted membranes such as δHm1. δHm2, and Trc have been also studied by using DSC

  17. HRP-Mediated Synthesis of Starch-Polyacrylamide Graft Copolymers

    Science.gov (United States)

    Modified starch-based polymers can be engineered for specific properties by combining starch with synthetic polymers through graft copolymerization. Polyacrylamide grafted starch have received a great deal of applications in areas such as superabsorbent paper-making additives, drag reduction and te...

  18. Sulfonated hydrocarbon graft architectures for cation exchange membranes

    DEFF Research Database (Denmark)

    Nielsen, Mads Møller; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    to various degrees. Series of grafting densities and graft lengths are prepared, and membranes are solvent cast from DMSO. The membrane properties in aqueous environments are evaluated from their water swelling behavior, and their thermal properties and stability are investigated by thermogravimetric...

  19. Study on biotribological properties of UHMWPE grafted with MPDSAH

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yaling; Xiong, Dangsheng, E-mail: xiongds@163.com; Shao, Silong

    2013-04-01

    In order to prolong the service life of artificial joints, a zwitterion monomer of MPDSAH ((3-(methacryloylamino)propyl)dimethyl (3-sulfopropyl)ammonium hydroxide) was grafted onto ultra-high molecular weight polyethylene (UHMWPE) powders to construct a brush-like structure by UV irradiation, and then the grafted UHMWPE powders were hot pressed as the bulk materials. The wettability of bulk materials surface with different monomer concentrations was analyzed. The tribological properties of modified UHMWPE bulk materials were investigated under distilled water and saline by sliding against stainless steel ball. The measurement of Fourier-transform infrared (FT-IR) spectroscopy indicates that MPDSAH is successfully grafted onto the surface of UHMWPE powders by UV irradiation. The contact angles of modified UHMWPE are decreased and the surface wettability is effectively improved. The friction coefficient of the modified sample is lower than that of untreated UHMWPE in aqueous lubricants during a long-term friction. With the increase of monomer concentration, the wear rate of grafted UHMWPE decreases gradually in distilled water. The grafting hydrophilic macromolecule polymer is helpful to form a lubricating film of water, which leads to the improvement of the lubricity of UHMWPE. - Highlights: ► PMPDSAH brushes were grafted onto UHMWPE powders by UV radiation. ► Wettability of PMPDSAH-grafted UHMWPE bulk material is improved. ► UHMWPE grafted with PMPDSAH brushes shows lower friction coefficient and wear rate.

  20. Experimental autologous substitute vascular graft for transplantation surgery

    NARCIS (Netherlands)

    Kobori, L; Dallos, G; Gouw, ASH; Nemeth, T; Nemes, B; Fehervari, I; Tegzess, Adam; Slooff, MJH; Perner, F; De Jong, KP

    2000-01-01

    Vascular complications in fiver transplantation are a major cause of graft failure and mortality. The aim of the study was to create autologous vascular graft without risk of rejection. Posterior rectus fascia sheath lined with peritoneum was used for iliac artery replacement in seven mongrel dogs.

  1. The use of irradiated tissue grafts in surgical practice

    International Nuclear Information System (INIS)

    Radiated tissue grafts are in vogue in various surgical corrective procedures. Tissue Banks are needed to preserve tissues of blood vessels, skin, cartilage, cornea, bone and fascia lata. Since 1988, Tata Memorial Hospital's tissue bank is functional and it uses gamma chamber. An attempt is made in this paper to discuss the advantages of the use of irradiated tissue grafts in surgical practice. (author)

  2. A device for a noninvasive evaluation of coronary bypass grafts.

    Science.gov (United States)

    McInerney, J J; Lamser, D G; Herr, M D

    1994-01-01

    A new device is presented for evaluating the patency of coronary bypass grafts. Bypass grafts are located within the chest cavity using a Compton backscatter imaging (CBI) technique that creates frontal plane tomographic images. The tomographic image pixels are mapped into computer memory and displayed. A display pointer is used to mark the position of the bypass graft. The computer uses that information to subsequently position a radiation detector, such that it "looks" at the location of the bypass graft within the closed chest. The patency of the graft is then evaluated by monitoring an X-ray induced iodine fluorescence transient in the graft, subsequent to a peripheral intravenous contrast injection. This imaging and graft evaluation device is relatively inexpensive and its application does not require cutdowns or catheterization. The associated radiation dose is 1/10 to 1/50 of that associated with alternative X-ray graft patency evaluation techniques. Preliminary testing has been performed on mechanical and animal models. PMID:18218544

  3. Solvent influence during radiation induced grafting of styrene in PVDF

    International Nuclear Information System (INIS)

    Radiation-induced grafting was studied to produce styrene grafted poly(vinylidene fluoride) (PVDF) membranes. PVDF films with 0.125 mm thickness were irradiated at doses between 5 and 20 kGy in the presence of styrene/N,N-dimethylformamide (DMF), styrene/acetone or styrene/toluene solutions (1:1, v/v) at dose rate of 5 kGy h-1 by simultaneous method, using gamma rays from a Co-60, under nitrogen atmosphere and at room temperature. The films were characterized before and after modification by grafting yield (GY %), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM and EDS), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose and toluene hinders the grafting, leading to a small GY comparing to DMF and acetone. It was possible to confirm the grafting of styrene by FT-IR due to the new characteristics peaks and by the TG and DSC due to changes in thermal behavior of the grafted material. SEM and EDS show surface and cross-section distribution of the grafting, which takes place on the surface and heterogeneously with toluene as solvent and homogeneously and penetrating into the inner layers of the matrix using DMF and acetone as solvent. (author)

  4. Stent Graft in Managing Juxta-Renal Aortoiliac Occlusion

    International Nuclear Information System (INIS)

    Endovascular procedures are frequently used as an alternative to surgical bypass in aortic and iliac occlusion. Stents have revolutionized the scope of such endovascular procedures, but there are few reports of stents or stent grafts in occlusive juxta-renal aortic occlusion. We present a case where such occlusion was managed by use of a stent graft with successful outcome

  5. Graft Copolymerization Of Methyl Methacrylate Onto Agave Cellulose

    International Nuclear Information System (INIS)

    The grafting polymerization of methyl methacrylate (MMA) and Agave cellulose was prepared and the grafting reaction conditions were optimized by varying the reaction time and temperature, and ratio of monomer to cellulose. The resulting graft copolymers were characterized by Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy (SEM). The experimental results showed that the optimal conditions were at a temperature of 45 degree Celsius for 90 min with ratio monomer to cellulose at 1:1 (g/ g). An additional peak at 1738 cm-1 which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted cellulose, respectively. Grafting of MMA onto cellulose enhanced its thermal stability and SEM observation further furnished evidence of grafting MMA onto Agave cellulose with increasing cellulose diameter and surface roughness. (author)

  6. Grafted hydroxypropyl guargum: Development, characterization and application as flocculating agent

    Indian Academy of Sciences (India)

    B R Nayak; D R Biswal; N C Karmakar; R P Singh

    2002-11-01

    Synthesis of hydroxypropyl guargum--polyacrylamide was carried out by ceric ion induced redox polymerization technique at 28 ± 1°C. The graft copolymer was characterized by IR and thermal analysis. The flocculation performance of graft copolymer was tested in 1 wt% coal suspension.

  7. Fibrocellular contraction of a lamellar posterior corneal graft

    DEFF Research Database (Denmark)

    Hjortdal, Jesper; Ivarsen, Anders; Heegaard, Steffen

    2011-01-01

    To report a case of progressive fibrotic contraction of the posterior lamellar graft after initially successful Descemet's stripping automated endothelial keratoplasty (DSAEK).......To report a case of progressive fibrotic contraction of the posterior lamellar graft after initially successful Descemet's stripping automated endothelial keratoplasty (DSAEK)....

  8. Serial Transmission of Plant Viruses by Cutting During Grafting

    Science.gov (United States)

    Reciprocal grafts of two tomato (Solanum lycopersicum L.) cultivars were made by hand using commercial grafting techniques. The razor blade used to cut rootstock or scion was first contaminated by making a single cut on tomato plants infected with either tomato spotted wilt virus (TSWV) or tomato m...

  9. Study on biotribological properties of UHMWPE grafted with MPDSAH

    International Nuclear Information System (INIS)

    In order to prolong the service life of artificial joints, a zwitterion monomer of MPDSAH ((3-(methacryloylamino)propyl)dimethyl (3-sulfopropyl)ammonium hydroxide) was grafted onto ultra-high molecular weight polyethylene (UHMWPE) powders to construct a brush-like structure by UV irradiation, and then the grafted UHMWPE powders were hot pressed as the bulk materials. The wettability of bulk materials surface with different monomer concentrations was analyzed. The tribological properties of modified UHMWPE bulk materials were investigated under distilled water and saline by sliding against stainless steel ball. The measurement of Fourier-transform infrared (FT-IR) spectroscopy indicates that MPDSAH is successfully grafted onto the surface of UHMWPE powders by UV irradiation. The contact angles of modified UHMWPE are decreased and the surface wettability is effectively improved. The friction coefficient of the modified sample is lower than that of untreated UHMWPE in aqueous lubricants during a long-term friction. With the increase of monomer concentration, the wear rate of grafted UHMWPE decreases gradually in distilled water. The grafting hydrophilic macromolecule polymer is helpful to form a lubricating film of water, which leads to the improvement of the lubricity of UHMWPE. - Highlights: ► PMPDSAH brushes were grafted onto UHMWPE powders by UV radiation. ► Wettability of PMPDSAH-grafted UHMWPE bulk material is improved. ► UHMWPE grafted with PMPDSAH brushes shows lower friction coefficient and wear rate

  10. 21 CFR 870.3450 - Vascular graft prosthesis.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vascular graft prosthesis. 870.3450 Section 870... prosthesis. (a) Identification. A vascular graft prosthesis is an implanted device intended to repair... Prostheses 510(k) Submissions.”...

  11. Structural grafts and suture techniques in functional and aesthetic rhinoplasty

    Directory of Open Access Journals (Sweden)

    Gassner, Holger G.

    2010-01-01

    Full Text Available Rhinoplasty has undergone important changes. With the advent of the open structure approach, requirements for structural grafting and direct manipulation of the cartilaginous skeleton through suture techniques have increased substantially. The present review analyzes the current literature on frequently referenced structural grafts and suture techniques. Individual techniques are described and their utility is discussed in light of available studies and data.

  12. Maleic anhydride grafting on EPDM rubber in the melt

    NARCIS (Netherlands)

    Oostenbrink, A.J.; Gaymans, R.J.

    1992-01-01

    The grafting of maleic anhydride on a EPDM rubber was studied with a twin screw extruder. The effect of barrel temperatures, throughput, maleic anhydride concentration and peroxide concentration [bis(t-butyl peroxy isopropyl)benzene] on the degree of grafting and melt viscosity was studied. The male

  13. Fat grafting for alleviating persistent pain after breast cancer treatment

    DEFF Research Database (Denmark)

    Juhl, Alexander A; Karlsson, Páll; Damsgaard, Tine E

    2016-01-01

    after mastectomy and whether fat grafting had a remodeling effect on the mastectomy scar. METHODS: This study was conducted as a randomized controlled trial. Patients were randomized to either receive fat grafting to the pain-afflicted area around the missing breast or a control group without any...

  14. PREPARATION AND APPLICATION OF DIMER ACID/LIGNIN GRAFT COPOLYMER

    Directory of Open Access Journals (Sweden)

    Run Fang

    2011-06-01

    Full Text Available Dimer acid (DA was grafted onto lignin (EHL to form a graft copolymer DA-g-EHL. The selection of the reaction type and the optimization of the reaction conditions for the grafting reaction were conducted through orthogonal and single factor experiments. FT-IR and thermal analysis were used to characterize the graft product. It was found that, compared with free radical grafting, DA can be grafted onto EHL more effectively by ester condensation with strongly acidic cation exchange resin as a catalyst. Under optimum reaction conditions, the increase of acid value and the yield of graft copolymer can reach about 9.3% and 83%, respectively. The application of DA-g-EHL in preparing modified phenolic aldehyde amine curing agent (PAA was studied. Results showed that the flexibility of the epoxy resin cured by DA-g-EHL modified PAA is significant higher than that of the resin cured by EHL modified PAA. The graft of DA onto EHL may reduce the rigidity of EHL and the chain stiffness of the PAA modified by EHL.

  15. Nursery and field serial grafting of Ilex paraguariensis

    Directory of Open Access Journals (Sweden)

    Delmar Santin

    2015-12-01

    Full Text Available The long time required to produce seedlings and the formation of plantations with low-quality genetic material are problems that need to be solved in the culture of yerba mate. Grafting for new plants production or for replacement of mate plants canopy may overcome those restrictions. However, that technique still lacks better investigation, especially regarding adult genetic material. Thus, we aimed to evaluate the effect of serial grafting (subcultures, clones, grafting environments and gender of parent plants in the survival and vitality of yerba mate grafts. An experiment with seedlings in a nursery was conducted in order to evaluate 3 subcultures and 2 clones. In another experiment, field and nursery environments were compared for six clones (three male and three female. The survival and vitality of grafts were evaluated for both experiments every 35 days and at the 105th day. The survival and vigor of grafts were affected by the clones and subcultures, there was a trend for the field ones to be superior to the nursery ones. Two subcultures were concluded to result in higher survival and vigor of yerba mate grafts, and those characteristics were concluded to be favored when grafting was directly conducted in the field and, especially, when the propagules came from female parent trees.

  16. A device for a noninvasive evaluation of coronary bypass grafts

    International Nuclear Information System (INIS)

    A new device is presented for evaluating the patency of coronary bypass grafts. Bypass grafts are located within the chest cavity using a Compton Backscatter Imaging (CBI) technique that creates frontal plane tomographic images. The tomographic image pixels are mapped into computer memory and displayed. A display pointer is used to mark the position of the bypass graft. The computer uses that information to subsequently position a radiation detector, such that it looks at the location of the bypass graft within the closed chest. The patency of the graft is then evaluated by monitoring an X-ray induced iodine fluorescence transient in the graft, subsequent to a peripheral intravenous contrast injection. This imaging and graft evaluation device is relatively inexpensive and its application does not require cutdowns or catheterization. The associated radiation dose is 1/10 to 1/50 of that associated with alternative X-ray graft patency evaluation techniques. Preliminary testing has been performed on mechanical and animal models

  17. Molecular Simulation Studies of Covalently and Ionically Grafted Nanoparticles

    Science.gov (United States)

    Hong, Bingbing

    Solvent-free covalently- or ionically-grafted nanoparticles (CGNs and IGNs) are a new class of organic-inorganic hybrid composite materials exhibiting fluid-like behaviors around room temperature. With similar structures to prior systems, e.g. nanocomposites, neutral or charged colloids, ionic liquids, etc, CGNs and IGNs inherit the functionality of inorganic nanopariticles, the facile processibility of polymers, as well as conductivity and nonvolatility from their constituent materials. In spite of the extensive prior experimental research having covered synthesis and measurements of thermal and dynamic properties, little progress in understanding of these new materials at the molecular level has been achieved, because of the lack of simulation work in this new area. Atomistic and coarse-grained molecular dynamics simulations have been performed in this thesis to investigate the thermodynamics, structure, and dynamics of these systems and to seek predictive methods predictable for their properties. Starting from poly(ethylene oxide) oligomers (PEO) melts, we established atomistic models based on united-atom representations of methylene. The Green-Kubo and Einstein-Helfand formulas were used to calculate the transport properties. The simulations generate densities, viscosities, diffusivities, in good agreement with experimental data. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. Coupled with thermodynamic integration methods, the models give good predictions of pressure-composition-density relations for CO 2 + PEO oligomers. Water effects on the Henry's constant of CO 2 in PEO have also been investigated. The dependence of the calculated Henry's constants on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. CGNs are modeled by the inclusion of solid-sphere nanoparticles into the atomistic

  18. Pediatric burn wound impetigo after grafting.

    Science.gov (United States)

    Aikins, Kimberly; Prasad, Narayan; Menon, Seema; Harvey, John G; Holland, Andrew J A

    2015-01-01

    Modern burn care techniques have reduced the risk of infection of the acute burn wound, resulting in more rapid healing and a lower incidence of graft loss. Secondary breakdown may still occur. The loss of epithelium in association with multifocal superficial abscesses and ulceration has been termed burns impetigo. This may result in considerable morbidity and require prolonged treatment. The events preceding development, the impact on the patient, and the ideal treatment appear unclear and poorly reported. In 5 years, between 2006 and 2011, 406 pediatric burns were treated with skin grafts, with 7% developing burns impetigo. Time to resolution ranged from 5 to 241 days: the mean time to complete healing was greatest with conservative management (96 days), followed by antibacterial dressings (37 days), oral antibiotics (36 days), topical steroids (16 days), and oral antibiotics in combination with topical steroids (13.5 days). Burns impetigo resulted in significant morbidity, requiring multiple visits to the treatment center and prolonged symptoms. Delay in diagnosis and treatment resulted in worse outcomes. Prompt consideration of burns impetigo should occur when postgraft patients present with suggestive clinical signs and treatment with oral antibiotics plus topical steroids should be considered. PMID:24823337

  19. An experimental study of nerve bypass graft

    Institute of Scientific and Technical Information of China (English)

    XU Jie; LI Xue-shi

    2008-01-01

    Objective: To study the use of a nerve "bypass" graft as a possible alternative to neurolysis or segmental resection with interposition grafting in the treatment of neuroma-in-continuity. Methods: A sciatic nerve crush injury model was established in the Sprague-Dawley rat by compression with a straight hemostatic forceps. Epineurial windows were created proximal and distal to the injury site. An 8-mm segment of radial nerve was harvested and coaptated to the sciatic nerve at the epineurial window sites proximal and distal to the compressed segment (bypass group). A sciatic nerve crush injury without bypass served as a control. Nerve conduction studies were performed over an 8-week period. Sciatic nerves were then harvested and studied under transmission electron microscopy. Myelinated axon counts were obtained. Results: Nerve conduction velocity was significantly faster in the bypass group than in the control group at 8 weeks (63.57 m/s±5.83 m/s vs. 54.88 m/s±4.79m/s, P<0.01). Myelinated axon counts in distal segments were found more in the experimental sciatic nerve than in the control sciatic nerve. Significant axonal growth was noted in the bypass nerve segment itself. Conclusion: Nerve bypass may serve to augment peripheral axonal growth while avoiding further loss of the native nerve.

  20. Evaluation the success of osseointegrated implants in maxillary sinus grafts

    Directory of Open Access Journals (Sweden)

    Rubens Eduardo Gigli

    2008-01-01

    Full Text Available Objective: To analyze implants placed in maxillary sinus grafts with biomaterial of bovine origin and platelet-rich plasma, observing bone neoformation and the clinical and histologic success rate presented.Methods: Analysis of the clinical findings was based on 36 maxillary sinus grafts with 101 implants placed in 30 patients with a mean age of 47 years, and the histologic analysis, based on nine samples of the 36 grafts performed, with a mean interval of 7.5 months time of the graft, the majority of patients being men with a mean age of 42 years. Results: Clinically, 91 implants placed were osseointegrated.Conclusion: Based on the results presented, it was concluded that when implants are placed in the maxillary sinus region grafted with biomaterial, they present a high success rate. ISRCTN24003246