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1

Primary vascular anastomosis in growing pigs: comparison of polypropylene and polyglycolic acid sutures.  

Science.gov (United States)

Stenosis remains a significant problem in vascular anastomoses performed in the growing patient. This study compares the growth of vascular anastomoses performed with either polypropylene or polyglycolic acid sutures. End-to-end infrarenal aortic anastomoses were performed in 18 piglets. Twelve were performed with polypropylene; in six all sutures were placed in a continuous fashion (Group 1A), and in the other six the posterior sutures were continuous and the anterior were interrupted (Group B). Six anastomoses were performed with polyglycolic acid sutures placed in a continuous fashion (Group 2). The animals were killed 6 months following operation. The abdominal aorta was removed, measured, burst tested, and subjected to histologic studies. All anastomoses were patent. There were no burst failures at 300 mm Hg mean pressure. All polypropylene sutures in Group 1A and the continuous portion in Group 1B had straightened without breaking. Straightening without polypropylene suture breakage resulted in stricture in three Group 1A anastomoses and one Group 1B anastomosis; there was intraluminal polypropylene suture material in two Group 1A and five Group 1B anastomoses. Bowstring formation of the straightened, continuous portion of the polypropylene suture in two Group 1A anastomoses and one Group 1B anastomosis resulted in adherent thrombus. Group 2 anastomoses were without stricture and were grossly indistinguishable from adjacent normal vessel. Histologic examination showed varying degrees of chronic inflammation in the polypropylene anastomoses but negligible inflammation in the polyglycolic acid anastomoses. These results suggest that continuous suture techniques with polypropylene in growing vessels may result in stenosis and/or thrombosis. Moreover, synthetic absorbable polyglycolic acid sutures will be of use in vascular anastomoses in growing patients and in cases in which exacting technique with minimal postsurgical inflammation may be crucial to patency. PMID:6262579

Pae, W E; Waldhausen, J A; Prophet, G A; Pierce, W S

1981-06-01

2

Evaluation of endoscopic laser excision of polypropylene mesh/sutures following anti-incontinence procedures.  

LENUS (Irish Health Repository)

We reviewed our experience with and outcome of the largest series to our knowledge of patients who underwent endoscopic laser excision of eroded polypropylene mesh or sutures as a complication of previous anti-incontinence procedures.

Davis, N F

2012-11-01

3

Polypropylene Suture Versus Skin Staples for Securing Mesh in Lichtenstein Inguinal Hernioplasty  

International Nuclear Information System (INIS)

Objective: To compare polypropylene suture and skin staples for securing mesh in Lichtenstein inguinal hernioplasty in terms of mean operating time and postoperative pain. Study Design: Randomized clinical trial. Place and Duration of Study: Surgical Ward, Combined Military Hospital, Kharian, from August 2011 to February 2012. Methodology: All individuals fulfilling inclusion criteria underwent elective Lichtenstein inguinal hernioplasty as admitted patients, under spinal anaesthesia and with aseptic measures. In group 1, during the operation, mesh fixation was done with 2/0 polypropylene suture and skin was closed with subcuticular 2/0 polypropylene suture whereas in group 2, the anchorage of mesh was done with skin staples and skin was closed with staples from the same stapler. Mean operative time and postoperative pain, assessed on a visual analog score, were compared between the groups. Results: The overall postoperative pain was lower (p = 0.026) when staples were used to anchor mesh. Moreover, operative time was also lower (37.42 A +- 2.69 minutes) in staple group versus (42.44 A +- 2.55 minutes in polypropylene group). Conclusion: Mean operating time and postoperative pain is less in securing mesh with skin staples as compared to polypropylene suture in Lichtenstein inguinal hernioplasty. (author)

4

Small Bowel Wall Response to Enterotomy Closure with Polypropylene and Polyglactin 910 Using Simple Interrupted Suture Pattern in Rats  

Directory of Open Access Journals (Sweden)

Full Text Available Effects of polypropylene and polyglactin 910 on enterotomy wound healing were investigated. Sixteen adult W istar albino rats (155.44±30.4 g w ere randomized into two study groups, A with polypropylene (n = 8 and B with polyglactin 910 (n = 8 following 1 cm mid-jejunal enterotomy incisions performed under ketamine/xylazine anaesthesia. Body weights changes were evaluated daily for eleven days and two rats from each group were euthanized at postoperative days 3, 5, 7 and 11. Following euthanasia, the enterotomy sites were examined for dehiscence and adhesion. Evidence of inflammatory reactions and fibroblast proliferation were also evaluated and scored. Leaks from enterotomy site were not observed. Adhesion scores in-group A (3.5 was statistically significant (p0.05 but higher fibroblasts count was recorded in Group A (2.625 compared with group B (1.375. Inflammatory responses in both groups were not statistically significant, although that of Group B was higher in response than group A. Enterotomy closure with polypropylene produced significant adhesion that may be linked with the texture of the suture, and the several knots characteristic of the simple interrupted suture pattern.

Eyarefe O. David

2010-07-01

5

Comparação entre o uso de fio inabsorvível (polipropileno e fio absorvível (poliglactina 910 na fixação de prótese de polipropileno em correção de defeitos músculo-aponeurótico da parede abdominal: estudo experimental em ratos Comparison between fixation of polypropylene mesh with polypropylene suture and polyglactin 910 suture for treatment of muscle-aponeurotic defects of abdominal wall: experimental study in rats  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Comparar a fixação da tela de prolipropileno na correção de defeitos músculo-aponeuróticos da parede abdominal com fio absorvível (poliglactina 910 e fio inabsorvível (polipropileno. MÉTODOS: Oitenta e um ratos machos da linhagem Wistar foram submetidos a ressecção longitudinal de um segmento músculo-aponeurótico e peritoneal (3x2 cm da parede abdominal, seguida por reforço com tela de polipropileno, em forma de ponte sobre a aponeurose. Foram distribuídos em dois grupos de acordo com o fio usado para fixação da tela: grupo poliglactina 910 - fixada com 8 pontos separados e eqüidistantes em forma de "U" com fio 4-0; e grupo polipropileno - fixada com fio 4-0. A pele foi suturada com fio de nylon 4-0. Após 90 dias, os animais foram submetidos à eutanásia e avaliados macroscopicamente, quanto à presença de hérnia e avaliação histológica da reação inflamatória crônica, absorção do fio e percentagem de fibrose pela técnica vídeo-morfométrica assistida por computador. Utilizaram-se as técnicas de coloração de hematoxilina-eosina e picrossírius. RESULTADOS: Não houve diferença estatisticamente significante entre os grupos, quanto à presença de hérnia incisional (p=0,194. Houve maior fibrose no grupo polipropileno pela avaliação histológica de reação inflamatória crônica, o que não foi verificado quando avaliado pela técnica vídeo-morfométrica (p=0,0005. Não houve diferença entre os grupos quando avaliados os gigantócitos, linfócitos e neutrófilos. Houve maior número de macrófagos no grupo polipropileno (p=0,02. Não houve absorção do fio poliglactina 910 após 90 dias. CONCLUSÃO: A fixação de tela de polipropileno pode ser feita com êxito com fios absorvíveis como a poliglactina 910.PURPOSE: The aim of this study is to assess fixation of a polypropylene mesh in the repair of incisional hernias comparing an absorbable (polyglactin 910 suture and an inabsorbable (polypropylene one. METHODS: Eighty-one male rats of the Wistar breed, weighing from 180g to 220g, were submitted to a longitudinally resection of a musculoaponeurotic and peritoneal segment (3x2 cm of the abdominal wall. Reconstruction was performed by reinforcement with polypropylene mesh, overlaid on the aponeurosis. They were distributed in two groups according to the thread used for mesh fixation as follows: (1 polyglactin 910 group, fixed with 8 stitches 4.0 Polyglactin 910 suture; and (2 Polipropylene group, fixed with 4.0 polypropylene suture. The skin suture was performed with 4.0 nylon continuous stitches. After 90 days, animals were sacrificed and submitted to macroscopic evaluation for the presence of hernias. Histologic samples were stained for Hematoxylin-Eosine and Sirius-Red and were assessed for signs of cicatrization such as chronic inflammatory reaction, fibrosis, suture absortion and percentage of fibrosis by computer-assisted video morfometric technic. RESULTS: There was no significant difference between the groups studied in relation to hernia formation (p=0,194. The histologic study showed significant increase of fibrotic reaction in the polipropylene group (p=0,0005, but this finding was not confirmed in the video-morfometric evaluation. Considering chronic inflammatory reaction, there was no difference between groups in relation to giant cells, lymphocytes and neutrophils. However, in the polipropylene group, macrophages were significantly increased (p=0,02. Polyglactin 910 has not been absorved 90 days after the procedure. CONCLUSIONS: The results of this study suggest that the fixation of polipropilene mesh is effective using absorbable sutures in the repair of ventral (incisional hernias.

Álvaro Gianlupi

2004-04-01

6

Comparação entre o uso de fio inabsorvível (polipropileno) e fio absorvível (poliglactina 910) na fixação de prótese de polipropileno em correção de defeitos músculo-aponeurótico da parede abdominal: estudo experimental em ratos / Comparison between fixation of polypropylene mesh with polypropylene suture and polyglactin 910 suture for treatment of muscle-aponeurotic defects of abdominal wall: experimental study in rats  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Comparar a fixação da tela de prolipropileno na correção de defeitos músculo-aponeuróticos da parede abdominal com fio absorvível (poliglactina 910) e fio inabsorvível (polipropileno). MÉTODOS: Oitenta e um ratos machos da linhagem Wistar foram submetidos a ressecção longitudinal de um seg [...] mento músculo-aponeurótico e peritoneal (3x2 cm) da parede abdominal, seguida por reforço com tela de polipropileno, em forma de ponte sobre a aponeurose. Foram distribuídos em dois grupos de acordo com o fio usado para fixação da tela: grupo poliglactina 910 - fixada com 8 pontos separados e eqüidistantes em forma de "U" com fio 4-0; e grupo polipropileno - fixada com fio 4-0. A pele foi suturada com fio de nylon 4-0. Após 90 dias, os animais foram submetidos à eutanásia e avaliados macroscopicamente, quanto à presença de hérnia e avaliação histológica da reação inflamatória crônica, absorção do fio e percentagem de fibrose pela técnica vídeo-morfométrica assistida por computador. Utilizaram-se as técnicas de coloração de hematoxilina-eosina e picrossírius. RESULTADOS: Não houve diferença estatisticamente significante entre os grupos, quanto à presença de hérnia incisional (p=0,194). Houve maior fibrose no grupo polipropileno pela avaliação histológica de reação inflamatória crônica, o que não foi verificado quando avaliado pela técnica vídeo-morfométrica (p=0,0005). Não houve diferença entre os grupos quando avaliados os gigantócitos, linfócitos e neutrófilos. Houve maior número de macrófagos no grupo polipropileno (p=0,02). Não houve absorção do fio poliglactina 910 após 90 dias. CONCLUSÃO: A fixação de tela de polipropileno pode ser feita com êxito com fios absorvíveis como a poliglactina 910. Abstract in english PURPOSE: The aim of this study is to assess fixation of a polypropylene mesh in the repair of incisional hernias comparing an absorbable (polyglactin 910) suture and an inabsorbable (polypropylene) one. METHODS: Eighty-one male rats of the Wistar breed, weighing from 180g to 220g, were submitted to [...] a longitudinally resection of a musculoaponeurotic and peritoneal segment (3x2 cm) of the abdominal wall. Reconstruction was performed by reinforcement with polypropylene mesh, overlaid on the aponeurosis. They were distributed in two groups according to the thread used for mesh fixation as follows: (1) polyglactin 910 group, fixed with 8 stitches 4.0 Polyglactin 910 suture; and (2) Polipropylene group, fixed with 4.0 polypropylene suture. The skin suture was performed with 4.0 nylon continuous stitches. After 90 days, animals were sacrificed and submitted to macroscopic evaluation for the presence of hernias. Histologic samples were stained for Hematoxylin-Eosine and Sirius-Red and were assessed for signs of cicatrization such as chronic inflammatory reaction, fibrosis, suture absortion and percentage of fibrosis by computer-assisted video morfometric technic. RESULTS: There was no significant difference between the groups studied in relation to hernia formation (p=0,194). The histologic study showed significant increase of fibrotic reaction in the polipropylene group (p=0,0005), but this finding was not confirmed in the video-morfometric evaluation. Considering chronic inflammatory reaction, there was no difference between groups in relation to giant cells, lymphocytes and neutrophils. However, in the polipropylene group, macrophages were significantly increased (p=0,02). Polyglactin 910 has not been absorved 90 days after the procedure. CONCLUSIONS: The results of this study suggest that the fixation of polipropilene mesh is effective using absorbable sutures in the repair of ventral (incisional) hernias.

Álvaro, Gianlupi; Manoel Roberto Maciel, Trindade.

2004-04-01

7

Comparação entre o uso de fio inabsorvível (polipropileno) e fio absorvível (poliglactina 910) na fixação de prótese de polipropileno em correção de defeitos músculo-aponeurótico da parede abdominal: estudo experimental em ratos / Comparison between fixation of polypropylene mesh with polypropylene suture and polyglactin 910 suture for treatment of muscle-aponeurotic defects of abdominal wall: experimental study in rats  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Comparar a fixação da tela de prolipropileno na correção de defeitos músculo-aponeuróticos da parede abdominal com fio absorvível (poliglactina 910) e fio inabsorvível (polipropileno). MÉTODOS: Oitenta e um ratos machos da linhagem Wistar foram submetidos a ressecção longitudinal de um seg [...] mento músculo-aponeurótico e peritoneal (3x2 cm) da parede abdominal, seguida por reforço com tela de polipropileno, em forma de ponte sobre a aponeurose. Foram distribuídos em dois grupos de acordo com o fio usado para fixação da tela: grupo poliglactina 910 - fixada com 8 pontos separados e eqüidistantes em forma de "U" com fio 4-0; e grupo polipropileno - fixada com fio 4-0. A pele foi suturada com fio de nylon 4-0. Após 90 dias, os animais foram submetidos à eutanásia e avaliados macroscopicamente, quanto à presença de hérnia e avaliação histológica da reação inflamatória crônica, absorção do fio e percentagem de fibrose pela técnica vídeo-morfométrica assistida por computador. Utilizaram-se as técnicas de coloração de hematoxilina-eosina e picrossírius. RESULTADOS: Não houve diferença estatisticamente significante entre os grupos, quanto à presença de hérnia incisional (p=0,194). Houve maior fibrose no grupo polipropileno pela avaliação histológica de reação inflamatória crônica, o que não foi verificado quando avaliado pela técnica vídeo-morfométrica (p=0,0005). Não houve diferença entre os grupos quando avaliados os gigantócitos, linfócitos e neutrófilos. Houve maior número de macrófagos no grupo polipropileno (p=0,02). Não houve absorção do fio poliglactina 910 após 90 dias. CONCLUSÃO: A fixação de tela de polipropileno pode ser feita com êxito com fios absorvíveis como a poliglactina 910. Abstract in english PURPOSE: The aim of this study is to assess fixation of a polypropylene mesh in the repair of incisional hernias comparing an absorbable (polyglactin 910) suture and an inabsorbable (polypropylene) one. METHODS: Eighty-one male rats of the Wistar breed, weighing from 180g to 220g, were submitted to [...] a longitudinally resection of a musculoaponeurotic and peritoneal segment (3x2 cm) of the abdominal wall. Reconstruction was performed by reinforcement with polypropylene mesh, overlaid on the aponeurosis. They were distributed in two groups according to the thread used for mesh fixation as follows: (1) polyglactin 910 group, fixed with 8 stitches 4.0 Polyglactin 910 suture; and (2) Polipropylene group, fixed with 4.0 polypropylene suture. The skin suture was performed with 4.0 nylon continuous stitches. After 90 days, animals were sacrificed and submitted to macroscopic evaluation for the presence of hernias. Histologic samples were stained for Hematoxylin-Eosine and Sirius-Red and were assessed for signs of cicatrization such as chronic inflammatory reaction, fibrosis, suture absortion and percentage of fibrosis by computer-assisted video morfometric technic. RESULTS: There was no significant difference between the groups studied in relation to hernia formation (p=0,194). The histologic study showed significant increase of fibrotic reaction in the polipropylene group (p=0,0005), but this finding was not confirmed in the video-morfometric evaluation. Considering chronic inflammatory reaction, there was no difference between groups in relation to giant cells, lymphocytes and neutrophils. However, in the polipropylene group, macrophages were significantly increased (p=0,02). Polyglactin 910 has not been absorved 90 days after the procedure. CONCLUSIONS: The results of this study suggest that the fixation of polipropilene mesh is effective using absorbable sutures in the repair of ventral (incisional) hernias.

Álvaro, Gianlupi; Manoel Roberto Maciel, Trindade.

8

Polypropylene; Polypropylene  

Energy Technology Data Exchange (ETDEWEB)

Basell has signed an agreement with the Saudi Sahara Petrochemical firm for the construction of a polypropylene plant of 450000 t/year at Al-Jubail (Saudi Arabia). This project plans the construction of a propane dehydrogenation unit too. These two units should start at the end of the year 2007. (O.M.)

Anon.

2004-12-01

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Effect of suture material on platelet deposition onto prosthetic material  

International Nuclear Information System (INIS)

Previous studies have demonstrated the importance of employing prosthetic material with minimal thrombogenicity. However, the role of different suture materials in early thrombotic events on prosthetic materials has not been examined. Experiments were designed to analyze the effects of suture on platelet graft interaction using an in vivo baboon hemocompatability screen. 111Indium labeled, autologous platelet deposition was determined on expanded polytetrafluoroethylene (ePTFE) containing suture lines of polypropylene (Prolene), polybutester (Novafil), and ePTFE (Gore-Tex). A significant increase in platelet deposition was noted not only at the suture line, but proximal and distal to it as well. The results were different for each of the sutures employed and suggest that the suture line may influence early platelet deposition in the perianastomotic region, not only at the suture line, but proximally and distally as well

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Electron beam sterilization surgical sutures, 2  

International Nuclear Information System (INIS)

Possibility of electron beam (1.5 MeV, Van de Graaff accelerator) sterilization of a polypropylene surgical suture was examined from the points of sterilization effect and material degradation by the reason of that ? ray sterilization has not been permitted of its high degree of degradation. The D values of B. pumilus ATCC 27142 dry spores were determined to be 0.11 x 104 Gy in air and 0.18 x 104 Gy under the nitrogen stream irradiation, and the sterilization doses for electron beam were calculated to be 1.6 x 104 Gy in air and 2.7 x 104 Gy under the nitrogen stream, corresponding to ? ray sterilization assurance level of 2.5 x 104 Gy. Tensile strength of the polypropylene suture was 95 % of original strength soon after electron beam irradiation in air and was changed to be 81 % after 6 months storage, this is within the limit of the recommended value of 80 %. Furthermore, heat treatment (85 deg C, 1 hr.) following irradiation reduced degradation of irradiated polypropylene: its tensile strength was 93 % soon after irradiation but 97 % after 6 months. In the case of irradiation under the nitrogen stream, tensile strength after 6 months storage was 73 % without heat treatment, but 93 % with heat treatment. Based on the above results, we concluded that electron beam sterilization is applicable to the polypropylene surgical suture used in this experiment and heat treatment successive irradiation is effective to restrain material degradation. (author)

11

Vascular anastomoses with absorbable suture material: an experimental study.  

Science.gov (United States)

A synthetic, monofilament, absorbable suture material, polytrimethylene carbonate, was tested to determine its suitability for use in arterial anastomoses. The material studied is a copolymer made of trimethylene carbonate and polyglycolic acid, with a retention time in the tissue of up to six months. In an experimental group of 12 mongrel dogs, using simple end-to-end anastomoses, aortic and femoral patch grafts of bovine heterograft material and iliofemoral bypass implants of 5 mm of expanded polytetrafluoroethylene prostheses were performed and arteriographically and histologically documented. Direct intraindividual comparisons were made with the absorbable (polytrimethylene carbonate) and nonabsorbable (polypropylene, expanded polytetrafluoroethylene suture) materials, a total of 108 anastomoses. No suture material-related complications such as ruptures or suture line aneurysms occurred. Polytrimethylene carbonate sutures led to less inflammation and scar tissue formation than polypropylene sutures. Complete absorption of the suture material by hydrolytic decomposition was followed by an almost complete regeneration in all layers of the vessel wall. Regeneration of the connective tissue structures of the media was noted. Initial associated reactions in the intima eventually disappeared. Both suture materials were equivalent histologically in the early months of the study, but after 10 month follow-up differences were observed, especially in the structure of the media, apart from the fact that polytrimethylene carbonate is absorbed completely after four to seven months. PMID:2064920

Schmitz-Rixen, T; Storck, M; Erasmi, H; Schmiegelow, P; Horsch, S

1991-05-01

12

Quantitative evaluation of stiffness of commercial suture materials.  

Science.gov (United States)

The bending stiffness of 22 commercial suture materials of varying size, chemical structure and physical form was quantitatively evaluated using a stiffness tester (Taber V-5, model 150B, Teledyne). The commercial sutures were Chromic catgut; Dexon (polyglycolic acid); Vicryl (polyglactin 910); PDS (polydioxanone); Maxon (polyglycolide-trimethylene carbonate); Silk (coated with silicone); Mersilene (polyester fiber); Tycron (polyester fiber); Ethibond (polyethylene terephthalate coated with polybutylene); Nurolon (nylon 66); Surgilon (nylon 66 coated with silicone); Ethilon (coated nylon 66), Prolene (polypropylene); Dermalene (polyethylene), and Gore-tex (polytetraflouroethylene). These are both natural and synthetic, absorbable and nonabsorbable and monofilament and multifilament sutures. All of these sutures were size 2-0, but Prolene sutures with sizes ranging from 1-0 to 9-0 were also tested to determine the effect of suture size on stiffness. The bending stiffness data obtained showed that a wide range of bending stiffness was observed among the 22 commercial sutures. The most flexible 2-0 suture was Gore-tex, followed by Dexon, Silk, Surgilon, Vicryl (uncoated), Tycron, Nurolon, Mersilene, Ethibond, Maxon, PDS, Ethilon, Prolene, Chromic catgut, coated Vicryl, and lastly, Dermalene. The large porous volume inherent in Gore-tex monofilament suture was the reason for its lowest flexural stiffness. Sutures with a braided structure were generally more flexible than those of a monofilament structure, irrespective of the chemical constituents. Coated sutures had significantly higher stiffness than the corresponding uncoated ones. This is particularly true when polymers rather than wax were used as the coating material. This increase in stiffness is attributable to the loss of mobility under bending force in the fibers and yarns that make up the sutures. An increase in the size of the suture significantly increased the stiffness, and the magnitude of increase depended on the chemical constituent of the suture. The flexural stiffness of sutures was also found to depend on the duration of bending in the test for stiffness. In general, monofilament sutures exhibited the largest time-dependent stiffness. This was most pronounced with the Gore-tex suture. Most braided sutures also showed less time-dependence in stiffness. Nylon sutures did not exhibit this time-dependent phenomenon regardless of physical form. PMID:2919353

Chu, C C; Kizil, Z

1989-03-01

13

[Ideal suture methods for skin, subcutaneous tissues and sternum].  

Science.gov (United States)

Non-absorbable sternal closure methods such as stainless steel wiring have been widely used, but biocompatibility and osteoconductivity of absorbable materials have advantages in acceleration of wound healing. Combined use of stainless steel wires with absorbable materials may contribute to minimizing sternal complications.Fascial tension reduction sutures, where the tension is placed on the layer of deep fascia and superficial fascia, are recommended for skin/subcutaneous closure. This means that the use of dermal sutures is minimized;indeed, dermal sutures can be avoided altogether if the wound edges can be joined naturally under very small tension. We prefer 0, 2-0 polydioxanone sutures (PDS II) for deep/superficial fascia sutures, 4-0 or 5-0 PDS II for dermal sutures (if they are necessary), and 6-0 or 7-0 polypropylene or nylon sutures (Proline or Ethilon) for superficial sutures. The consequence of such suturing is that the wound edges are elevated smoothly with minimal tension on the dermis that appears to prevent the development of large scars. PMID:22485038

Ogawa, Rei

2012-04-01

14

Ag??ZnO(10 0??????????  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????Ag??ZnO(10 0????????????????????Ag??ZnO(10 0?????????Ag??ZnO (10 0????????????????????ZnO(10 0???Ag??ZnO(10 0?????????????????Ag??ZnO(10 0?????????????Ag????????????????Ag??????????????????????????????????????????Ag??ZnO(10 0?????p???????p????????Ag??ZnO(10 0?????????????p????Based on the density function theory, we have performed first principles calculations of energetic stability and conductive properties and electronic structure of Ag incorporation on ZnO (10 0 surface, and after calculations, we have analyzed the relaxation of the structure and formation energy of Ag incorporation on ZnO (10 0 surface at different layers. Our results show that com-pared with pure ZnO (10 0, there is an obvious effect on the relaxation of the structure for Ag incorporation on ZnO (10 0 surface. Simultaneously, we found that the formation energy of the Ag incorporation on the first layer is the lowest in all cases. Therefore, Ag incorporation on the first layer is the most stable, which indicates that Ag atom prefers to collect in the surface layer instead of the bulk. And we found that the system for Ag incorporation on ZnO (10 0 surface demonstrates as p-type, which is in favors of fabricating p-type material. However, the ionization of Ag incorporation on ZnO (10 0 surface is much higher, which hinders the electronic ionize.

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2014-08-01

15

[The role of suture material on healing of vascular anastomosis].  

Science.gov (United States)

The effect of suture material on healing of vascular anastomosis was examined. Four types of vascular grafts, i.e., autogenous vein, preserved human umbilical cord vein, expanded polytetrafluoroethylene and double velour knitted Dacron, were implanted into the abdominal aorta of 78 adult mongrel dogs using two kinds of absorbable sutures (multifilament polyglycolic acid: PGA and monofilament polydioxanone: PDS) and a nonabsorbable suture (polypropylene: PP). The macroscopic findings and the histologic examinations showed that hyalinoid degeneration and calcification resulting from tissue ischemia due to tight and long lasting suture loops interfered with tissue healing at the PP-anastomotic site. On the other hand, fairly good healing of the anastomoses was observed with absorbable sutures because of the reduction of ischemia. The absorbable suture-anastomoses could tolerate systemic blood pressure within one month after implantation, and there was no anastomotic disruption at 1000 mmHg pressure in the bursting test 12 months after grafting. From Dec., 1984, 55 anastomoses in 34 bypass-operations employing autogenous vein grafts were performed using PGA and PDS in 28 cases clinically. There were no anastomotic complications. In conclusion, the synthetic absorbable suture material, especially in the form of monofilament, seems to be most suitable for suturing or anastomosing autogenous small vessels at present. PMID:2552281

Naoe, A

1989-06-01

16

An innovative method to evaluate the suture compliance in sealing the surgical wound lips  

Directory of Open Access Journals (Sweden)

Full Text Available Background and aim: The increasing number of surgical procedures performed with local anesthesia, followed by immediate patient discharge from the hospital, emphasizes the need for a tight waterproof suture that is capable of maintaining its tensile strength in the postoperative phase when the wound tumescence, edema due to the anesthetic drug, and surgical trauma disappear. Moreover, the issue of having an accurate surgical wound closure is very relevant in vivo in order to prevent hemorrhage and exogenous microbial infections. This study aimed at designing a new a lab technique that could be used for evaluating the best surgical material. Using such a technique, we compared the wound-lip-sealing properties of three commonly-used suture threads, namely polyurethane, polypropylene, and polyamide. Materials and methods: The mechanical properties of same-size suture threads made from polyurethane, polypropylene, and polyamide, were compared in order to define the one that possess the best elastic properties by being able to counteract the tension-relaxation process in the first 12 hours following surgery. The tension holding capacity of the suture materials was measured in both in vivo and in vitro experiments. The surface area of the scar associated with the three different suture threads was measured and compared, and the permeability of the three different suture threads was assessed at 0 minute, 2 minute, 4 minute, 6 minute, and 8 minute- interval. Results: Results showed that polyurethane suture threads had significantly (P < 0.05 better tensile strength, elongation endurance before breakage, and better elasticity coefficient as compared to polypropylene and polyamide suture threads. Moreover, polyurethane suture threads were significantly (P < 0.05 more impermeable as compared to the other two suture thread types (polypropylene and polyamide. This impermeability was also associated with a tighter wound-lip-sealing ability, and with significantly (P < 0.05 less scar formation. Conclusion: Among the main concerns that surgeons, physicians, and patients often have is the development infection, oozing, and scar at the incision site following suturing. This always raises the question about which suture to use to avoid the above problems. This study provides evidence that the new technique developed in our lab could be used to compare the wound-lip sealing properties of different surgical suture threads. Using such a technique, the results show that polyurethane is significantly better than other commonly-used suture threads, like polypropylene and polyamide, in relation to wound sealing and scar formation.

Farid Saleh, Beniamino Palmieri, Danielle Lodi, Khalid Al-Sebeih

2008-01-01

17

Radiochemical sterilization and its use for sutures  

International Nuclear Information System (INIS)

Radiochemical sterilization (RC-S) represents a novel approach to medical device sterilization. It is a hybrid process encompassing the attributes of chemical and high-energy radiation sterilization without the drawbacks associated with the use of the parent processes. It entails the use of a 5-7.5 kGy of ? radiation and a polyformaldehyde insert capable of a radiolytic-controlled release of formaldehyde gas in a hermetically sealed package under dry nitrogen. The RC-S process has been applied successfully to radiation-sensitive sutures, namely polypropylene monofilaments and absorbable polyglycolide braids

18

New-Fangled Slowly-Absorbable versus Non-Absorbable Sutures for Abdominal Fascial Closure. Have the Goals towards an Advantageous Suture Been Met?  

Directory of Open Access Journals (Sweden)

Full Text Available Background-Aim: The technique of abdominal closure along with the material to be used is constantly evolving. The aim of the present study is to evaluate differences in midline laparotomy closure with a standard closure technique and new-fangled slow-absorbable versus non-absorbable sutures. Material and Methods: A prospective, comparative study of patients undergoing laparotomy closure with either STARDIOX (Polydioxanone or STARLENE (Polypropylene sutures during a 9 month period was performed. Patients were evaluated and compared in terms of surgical site infection, incisional hernia, burst abdomen, and suture sinus formation. Results: A total of 284 patients were included [141 in the STARDIOX (Polydioxanone group and 143 in the STARLENE (Polypropylene group]. Sinus formation was not noticed and no palpable knots were reported in both groups. Moreover burst abdomen was never encountered. Incisional hernia rates were similar for both suture materials: n = 6 (4.3% for the STARDIOX (Polydioxanone group and n = 5 (3.5% for the STARLENE (Polypropylene group. There was not statistically significant relationship between the type of suture that was used and wound infection: n = 5 (3.5% in the STARDIOX (Polydioxanone group and n = 6 (4.2% in the STARLENE (Polypropylene group. Complications did not occur in 96.1% of all patients. Conclusions: Our study suggests that there are no significant differences between these two new-fangled sutures. It seems that progress of suture materials has led to a step towards the goals of a beneficial suture and from then on complications of surgical wound closure should be merely a matter of operative technique.

Georgios Anthimidis

2013-05-01

19

The sutured Thurston norm  

CERN Document Server

For sutured 3-manifolds M, there is a sutured Thurston norm due to Scharlemann. We show how depth one foliations of M and corresponding fibrations and the usual Thurston norm on the double of M are useful tools for computing this norm. In many examples, the faces of the unit ball of the sutured norm are related to cones of depth one foliations of M but examples indicate this is not a general relationship.

Cantwell, J; Cantwell, John; Conlon, Lawrence

2006-01-01

20

15 CFR 10.0 - General.  

Science.gov (United States)

...0 Section 10.0 Commerce and Foreign Trade Office of the Secretary of Commerce PROCEDURES FOR THE... The Department of Commerce (hereinafter referred to...recognizes the importance, the advantages, and the...

2010-01-01

 
 
 
 
21

Band taut sutured manifolds  

CERN Document Server

Attaching a 2-handle to a genus two or greater boundary component of a 3-manifold is a natural generalization of Dehn filling a torus boundary component. We prove that there is an interesting relationship between an essential surface in a sutured 3-manifold, the number of intersections between the boundary of the surface and one of the sutures, and the cocore of the 2-handle in the manifold after attaching a 2-handle along the suture. We use this result to show that tunnels for tunnel number one knots or links in any 3-manifold can be isotoped to lie on a branched surface corresponding to a certain taut sutured manifold hierarchy of the knot or link exterior. In a subsequent paper, we use the theorem to prove that band sums satisfy the cabling conjecture, and to give new proofs that unknotting number one knots are prime and that genus is superadditive under band sum. To prove the theorem, we introduce band taut sutured manifolds and prove the existence of band taut sutured manifolds.

Taylor, Scott A

2011-01-01

22

Layer closure of laparotomy wounds with absorbable and non-absorbable suture materials.  

Science.gov (United States)

Opinions vary regarding the best suture material for abdominal wound closure. Some surgeons favour non-absorbable sutures while others use absorbable materials, but there is little objective clinical information regarding the relative merits of the different suture materials. In a randomized prospective clinical trial the synthetic absorbable polyglactin and polyglycolic acid sutures were compared with the non-absorbable polypropylene suture in the closure of 161 laparotomy wounds. A layered closure technique was used in all cases. The total incidence of wound dehiscence and herniation was 8-1 per cent, and there was no significant difference between polylycolic acid (9-6 per cent), polyglactin (5-8 per cent) and polypropylene (8-8 per cent). Dehiscence and herniation were significantly more common in wounds closed by surgeons in training. It was concluded that none of the suture materials provided satisfactory freedom from wound complications. It is possible that these sutures may prove satisfactory with an alternative technique of abdominal wound closure, but this should be the subject of further clinical studies. PMID:791437

Irvin, T T; Koffman, C G; Duthie, H L

1976-10-01

23

Fatigue testing of suture anchors.  

Science.gov (United States)

In a porcine tibia model, we subjected widely used anchor-suture combinations to a fatigue-testing protocol. The Ethibond No. 2 suture was the weakest part of the anchor-suture combinations when they were loaded to failure by a single pull. Under cyclic-loading conditions, fixation strength was decreased compared with single-pull tests. The suture/anchor interface was identified as the weakest link in the Mitek GII/No. 2 combination and in the Zimmer Statak 3.5/No. 2 combination. In most cases the suture was worn through at the eyelet. Threading the GII anchor with a No. 5 suture and use of larger anchors in combination with No. 2 sutures increased the fatigue strength. Suture breakage at the knot was the predominant failure mode for biodegradable anchors inserted into cortical bone. The highest fatigue strength was seen for the Super Anchor/No. 5 combination when the anchor was inserted in cortical bone. Fatigue testing is crucial for evaluation of suture anchors and should be performed along with single-pull testing. The mechanical performance of a suture anchor threaded with a defined suture depends on several key factors: the pullout strength of the anchor, the tensile strength of the suture, and the interaction of anchor and suture at the eyelet (suture/anchor interface). PMID:11912095

Rupp, Stefan; Georg, Thomas; Gauss, Christian; Kohn, Dieter; Seil, Romain

2002-01-01

24

USE OF POLYPROPYLENE MESH FOR INCISIONAL HERNIA REPAIR  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Incisional hernia is an important complication of abdominal surgery. Procedures for the repair of these hernias with sutures and with mesh have been reported, but there is no consensus about which type of procedure is the best. We have performed a retrospective analysis on 1128 patients operated on in our unit between 1994 and 2004 for simple or recurrent incisional hernias. The polypropylene mesh has been used in a number of 138 patients. The mesh has been placed either intraperitone...

Scripcariu V; Timofte D; Timofeiov S; Lefter L; Radu I; Dragomir C

2006-01-01

25

Radiation resistant polypropylene  

International Nuclear Information System (INIS)

The specially modified polypropylene for medical use has been worked out at the Institute of Nuclear Chemistry and Technology, Warsaw (Patent no. P-295304). Its applicability for medical supplies manufacturing being appropriate to radiation sterilization has shown. The chemical and mechanical properties of presented material have been shown and compared with other modified polypropylene available in the world market. 2 figs, 1 tab

26

Selective suture cutting for control of astigmatism following cataract surgery  

Directory of Open Access Journals (Sweden)

Full Text Available Use of 10-0 monofilament nylon in ECCE cataract surgery leads to high with the rule astigmatism. Many intraoperative and post operative methods have been used to minimise post operative astigmatism. We did selective suture cutting in 38 consecutive patients. Mean keratometric astigmatism at three and six weeks post operative was 5.76 and 5.42 dioptres (D respectively. 77.5% of eyes had astigmatism above 2 D. Selective suture cutting along the axis of the plus high cylinder was done after six weeks of surgery. Mean post suture cutting keratometric astigmatism was 3.3 D and 70% of the eyes had astigmatism below 2 D. After 3 months of surgery mean keratometric astigmatism was reduced to 1.84 D. Axis of the astigmatism also changed following suture cutting. 40% of the eyes showed improvement in their Snellen acuity following reduction in the cylindrical power.

Bansal R

1992-01-01

27

Evaluation of 9-0 polyglycolic acid and polyglactin suture in rabbit limbal wounds.  

Science.gov (United States)

Sutures of 9-0 polyglycolic acid (Dexon) or polyglactin (Vicryl) were used to close limbal incision in rabbit eyes. The handling properties of both sutures were excellent and tissue reaction minimal. The majority of sutures disappeared four to six weeks postoperatively. Small areas of anterior wound gaping without leak occurred in half the eyes. While the performance of this suture was superior to that of 10-0 synthetic absorbables studied previously, it is advised that clinical application be approached with caution. PMID:6247679

Sugar, A

1980-05-01

28

Radiation treatment of polypropylene  

International Nuclear Information System (INIS)

Structural changes in polypropylene resulting from high energy electron beam irradiation have been examined. Polymer irradiated in a nitrogen atmosphere is characterized as containing long chain branch structures. A branching index, defined as the ratio of intrinsic viscosity of irradiated polymer to the intrinsic viscosity of linear polymer of equivalent molecular weight, is used to quantify the extent of branching. Polymer crystallization and solution properties undergo significant changes as a result of radiation treatment. Treated polypropylene is highly nucleated. Nucleation density is several orders of magnitude greater than linear polypropylene. Temperature rising elution fractionation (TREF) indicates that the long-chain branched structure contributes to increasing the solubility of polypropylene without greatly reducing the crystallizability and melting point of the solubilized fractions. The presence of long chain branching has a pronounced effect on the polymers extensional rheology in the molten state. Radiation treated polymer exhibits strain hardening elongational viscosity

29

Radiation resistant modified polypropylene  

International Nuclear Information System (INIS)

Radiation technology for production of radiation resistant polypropylene for medical use has been presented. The method consists in radiation induced copolymerization of polypropylene with ethylene and addition of small amount of copolymer of polyethylene and vinyl acetate. The material of proposed composition has a very good mechanical properties and elevated radiation resistivity decided on possibility of radiosterilization of products made of this material and designed for medical use. 3 figs, 3 tabs

30

Suturas mecânicas Mechanic sutures  

Directory of Open Access Journals (Sweden)

Full Text Available The authors review the use of staplers in General Surgery, mainly in Gastroenterological Surgery highlighting safety and effectiveness. They emphasize that the mechanic anastomosis are a viable technique and in some conditions, the best way to perform the anastomosis. The use of staplers makes surgery faster and easier and complications are, generally related to surgeon's experience in using them. Although its costs are higher compared to handsewn suture, it can make the patient total cost lower.

Alexandre Miranda Duarte

2002-10-01

31

Use of chitosan membrane associated with polypropylene mesh to prevent peritoneal adhesion in rats.  

Science.gov (United States)

The correction of wall abdominal defects often requires the use of implants such as polypropylene meshes. In spite of presenting good tissue acceptance, these biomaterials can migrate to adjacent viscera, promote enterocutaneos fistulas, tissue adherence and visceral erosions. In this work, the barrier effect of chitosan films associated with polypropylene meshes on adhesion formation experimentally induced in Wistar rats was evaluated. The animals were divided into two groups with 10 animals each. Animals in the CPP group were implanted with chitosan films associated with polypropylene meshes, whereas the ones in the PP group received only polypropylene meshes. After 8 days, the animals were submitted to euthanasia using CO(2) and a descriptive study focusing adhesion formation, visceral involvement with sutures and mesh peritonization was performed. Also, subimplanted material was collected for histopathology analysis. The results showed that the CPP group presented weak adhesions to the omentum over the stitch knots in eight animals. In all animals, the meshes were peritonized, not allowing their visualization after removing the chitosan films. In the PP group, six animals presented intestinal adhesions to the meshes and, in one of them, hepatic adhesion to the mesh was observed, besides omentum adhesion on more than 50% of the mesh area. The protective effect of chitosan films when sutured over polypropylene meshes, as well as no exacerbation of inflammation associated to the peritoneal lesions was statistically demonstrated. Therefore, chitosan films can indeed minimize the formation of peritoneal adhesions induced by polypropylene meshes in rats. PMID:19399842

Paulo, Neusa Margarida; de Brito e Silva, Marcelo Seixo; Moraes, Angela Maria; Rodrigues, Ana Paula; de Menezes, Liliana Borges; Miguel, Marina Pacheco; de Lima, Flávia Gontijo; de Morais Faria, Aline; Lima, Lívia Maria Lindoso

2009-10-01

32

Comparative study between two techniques of incisional hernia repair with polypropylene mesh in rabbits Estudo comparativo entre duas técnicas de tratamento da hérnia incisional em coelhos utilizando a tela de polipropileno  

Digital Repository Infrastructure Vision for European Research (DRIVER)

PURPOSE: To compare two different incisional hernia repair techniques (repair with a polypropylene mesh reinforcement on the peritonium-aponeurosis versus polypropylene mesh sutured to the borders of the hernial ring as a bridge) in rabbits. METHODS: Incisional hernia was experimentally developed through a 4-cm median incision in 60 rabbits. After 30 days, half of the animals were operated for primary wall closure and placement of a polypropylene mesh reinforcement, while the other half had a...

José Guilherme Minossi; Carlos Antonio Caramori; Celso Vieira de Souza Leite; Luiz Eduardo Naresse

2010-01-01

33

The reaction of nerve tissue to various suture materials: a study in rabbits.  

Science.gov (United States)

Adult, male white New Zealand rabbits were used to compare two new synthetic suture materials, polyglycolic acid (Dexon) and polypropylene (Prolene), with wire, plain catgut, and silk. The purpose of the study was simply to determine the reaction of nerve tissue to each of the five different materials. No attempt was made to measure functional results. The nerves were examined grossly and microscopically in an effort to evaluate which suture incited the least host reaction. Although no difference was noted in the initial cellular response, Prolene was shown to incite the least fibrolastic response. Silk evoked the most marked fibroblastic response. PMID:839053

DeLee, J C; Smith, M T; Green, D P

1977-01-01

34

Influence of suture regularity on corneal astigmatism after penetrating keratoplasty  

DEFF Research Database (Denmark)

Abstract. Purpose: To investigate whether suture regularity affects corneal astigmatism after keratoplasty. Methods: Twenty-one patients undergoing penetrating keratoplasty for various corneal diseases were included in the study. The grafts were sutured in place using a single-running Nylon 10-0 suture, taking 24 bites. Immediately after surgery, standard calibrated images of the grafted eye were captured and stored. Using a dedicated image analysis programme, stitches and needle points were identified, and a number of suture regularity variables were calculated. Corneal topographic images were obtained before suture removal (12 months after surgery) and 3 months after suture removal (18 months after surgery). Topographic measures of astigmatism [surface regularity (SRI), surface asymmetry index (SAI) and simulated keratometric astigmatism] were calculated and correlated with the computed suture regularity variables. Results: The average stitch length was 3.04 +/- 0.28 mm and the distance between the outer needle points was 2.53 +/- 0.09 mm. The SRI was 1.26 +/- 0.36 and the SAI was 1.59 +/- 0.67 after 12 months; these decreased to 1.03 +/- 0.48 and 0.92 +/- 0.46 after 18 months, respectively. Corneal astigmatism was 6.38 +/- 2.99 and 5.87 +/- 3.13 dioptres after 12 and 18 months, respectively. Suture regularity did not affect SAI, SRI or corneal astigmatism significantly 12 months after surgery. Eighteen months after surgery (3 months after suture removal), the standard deviation on the original stitch length was found to significantly increase corneal astigmatism. In addition, the size of the counter-clockwise angle between stitch and graft radian was correlated significantly with a lower SRI. Conclusion: The origin of corneal astigmatism after penetrating keratoplasty is multifaceted. Regular stitch length and stitch advancement on the surface appears to improve the optical quality of the graft after suture removal. Factors such as stitch depth, suture tension and variations in wound construction might also beimportant predictors of corneal astigmatism after penetrating keratoplasty.

Hjortdal, Jesper; SØndergaard, Anders

2011-01-01

35

Polyglycolic acid suture in peripheral nerve II: sutured sciatic nerve.  

Science.gov (United States)

This experiment investigates the holding property of polyglycolic acid suture in repair of divided dog sciatic nerves and the influence of absorption of this synthetic material on regeneration. The conclusion is that PGA maintains its tensile strength sufficently long to allow both physical union and good regeneration of the divided nerve. The suture absorption does not influence regeneration. PMID:1253006

Hudson, A R; Hunter, D

1976-02-01

36

Cecorraphy in single layer using polypropylene and poliglecaprone 25 threads: comparative study in rats Cecorrafia em plano único com fios de polipropileno e poliglecaprone 25: estudo comparativo em ratos  

Digital Repository Infrastructure Vision for European Research (DRIVER)

PURPOSE: To compare sutures with polypropylene and poliglecaprone 25 after partial cecotomy in rats. METHODS: Thirty six rats divided into two groups, A and B, of 18 animals; each group was also divided into three subgroups of six animals sacrificed at 4th, 7th and 14th days after surgery. Were studied the mortality, morbidity, complications attributable to sutures, macroscopy, optical microscopy and measurement of hydroxyproline at the level of the suture. RESULTS: There were no deaths or wo...

Fernando Issamu Tabushi; Luiz Masakatso Nomura; Osvaldo Malafaia; Jurandir Marcondes Ribas-Filho; Benur Polonio; João Carlos Domingues Repka; Sergio Ioshii; Octavio Antonio Azevedo da Costa-Filho

2012-01-01

37

Mechanical performance of monofilament synthetic absorbable sutures.  

Science.gov (United States)

The purpose of this study was to evaluate the mechanical performance of two new synthetic monofilament absorbable sutures. The polydioxanone sutures is prepared by polymerizing and extruding the monomer, paradioxanone, in the presence of a suitable catalyst. The other suture is a modified polyglycolic acid suture, made by reacting trimethylene carbonate and glycolide. The knot configuration (1 = 1 = 1, 1 x 1 x 1, and 2 = 1 = 1) required for knot security was identical for the two synthetic monofilament sutures. The mean knot breaking strengths for the polydioxanone and modified polyglycolic acid sutures did not differ significantly. The surfaces of these sutures exhibited a low coefficient of friction which was slightly increased by hydration. The most distinctive difference between the handling characteristics of these two sutures was their flexural rigidity. The stiffness of the polydioxanone suture was 60 percent greater than that of the modified polyglycolic acid suture. PMID:3118727

Rodeheaver, G T; Powell, T A; Thacker, J G; Edlich, R F

1987-11-01

38

Suturing techniques and postoperative management in penetrating keratoplasty in the United Kingdom  

Science.gov (United States)

Aims To report on the suturing techniques and aspects of postoperative management in penetrating keratoplasty in the United Kingdom. Methods A postal questionnaire was sent to 137 ophthalmic consultants identified from a Royal College of Ophthalmology database as having a special interest in anterior segment surgery. The questionnaire surveyed surgeon preferences for surgical and suturing technique for penetrating keratoplasty surgery, and the postoperative care of corneal grafts. Results In all, 68% of questionnaires were completed and returned: 73% of respondents used a Flieringa ring or equivalent, 94% routinely used cardinal sutures, with 50.5% removing them at the end of the procedure. The most common suturing technique for routine penetrating keratoplasty was a single continuous suture (35%). In these cases, a 10/0 nylon suture was used by 89%. Sixty-six percent changed their technique in high-risk cases, 52% used a 3-1-1 knot, and 75% made a distinction between a reef and granny knot, with 76% using a reef. Thirty percent buried the knots within the donor material, and 29% within the host tissue. Twenty-five percent had no routine time for graft suture removal, but 41% removed them between 1 and 2 years post-surgery. After suture removal, 98% used steroids and 88% used topical antibiotics. Thirty-four percent stopped topical steroids before suture removal, with 38% stopping topical steroids more than 3 months prior to suture removal. Conclusion This survey demonstrates that there is considerable variation in suturing techniques and postoperative care for penetrating keratoplasty. These significant variations in practice need to be considered when interpreting outcomes and research. PMID:22942639

Lee, Richard MH; Lam, Fook Chang; Georgiou, Tassos; Paul, Bobby; Then, Kong Yong; Mavrikakis, Ioannis; Avadhanam, Venkata S; Liu, Christopher SC

2012-01-01

39

Fiber reinforced polypropylene nanocomposites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this thesis is to assess the feasibility of integrating nanoparticles into glass fiber (GF) reinforced isotactic polypropylene (iPP) composites via existing thermoplastic processing routes, and to investigate whether this results in significant improvements in the mechanical properties of the final composites. A longer term aim will be to extend the approach to the preparation of hybrid composites with added non-structural functionality. However, the nanoparticles that have provide...

Houphouet-boigny, Chryste?le; Ma?nson, Jan-anders E.; Plummer, John Christopher

2008-01-01

40

Fiber reinforced polypropylene nanocomposites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this thesis is to assess the feasibility of integrating nanoparticles into glass fiber (GF) reinforced isotactic polypropylene (iPP) composites via existing thermoplastic processing routes, and to investigate whether this results in significant improvements in the mechanical properties of the final composites. A longer term aim will be to extend the approach to the preparation of hybrid composites with added non-structural functionality. However, the nanoparticles that have provide...

Houphouet-boigny, Chryste?le

2007-01-01

 
 
 
 
41

Repair of complex giant ventral hernias with polypropylene and omentoplasty.  

Science.gov (United States)

The Authors in this report describe their experience with complex giant ventral hernias repaired by omentoplasty and polypropylene meshes. They explain their own technique of using the omentum when there is a lack of tissue and the need of an autologous tissue to place between the viscera and the above-lying polypropylene mesh. Among the 5 patients repaired, 4 had a giant sub-umbilical midline ventral hernia and one had a giant border ventral hernia. In all patients, the omentum was placed between the viscera and the mesh, which was fixed by interrupted sutures to the above-lying musculoaponeurotic plane. No complications, signs of bowel obstruction, or recurrences occurred. The Authors stress the omentum as an ideal tissue because of its biocompatibility and prevention of adhesions and fistulas allowing the use of a rigid and efficient prosthesis such as polypropylene. Thus, on the basis of their own short- and long-term good results, they suggest, whenever possible and necessary, the use of omentoplasty to repair complex giant ventral hernias. PMID:10738613

Sperlongano, P; Pisaniello, D; Pone, D

1999-01-01

42

Clinical Outcome and Wound Healing following Carpal Tunnel Decompression: A Comparison of Two Common Suture Materials  

Science.gov (United States)

Introduction. Debate exists amongst surgeons regarding the ideal suture material for skin closure in carpal tunnel decompression (CTD). This study compares wound related complications, patient satisfaction, and functional outcome following open carpal tunnel decompression in patients undergoing wound closure with either of two common absorbable and nonabsorbable suture types. Materials and Methods. 53 patients underwent CTD with either 4/0 polypropylene (ProleneTM, n = 28) or 4/0 polyglactin (Vicryl RapideTM, n = 25) for skin closure. QuickDASH, VAS satisfaction scores, and Southampton wound scores were assessed preoperatively and at 2 and 6 weeks postoperatively. Results. At 6 weeks the mean QuickDASH scores postoperatively were 18.54 and 17.70 for absorbable and nonabsorbable sutures, respectively, (P = 0.86). The mean VAS scores were 0.61 and 0.42 (P = 0.91), respectively. All patients achieved a Southampton wound score of 0 by 6 weeks except one, who achieved 1C in the nonabsorbable group, equivalent to mild erythema. There were no complications in either group. Conclusion. Both suture types are safe and effective materials for CTD, and we recommend surgeons to choose according to personal preference, handling properties, and resources available for suture removal. PMID:25165693

MacFarlane, Robert J.; Donnelly, Thomas D.; Morapudi, Syam; Waseem, Mohammad

2014-01-01

43

Torsion of monofilament and polyfilament sutures under tension decreases suture strength and increases risk of suture fracture.  

LENUS (Irish Health Repository)

A continuous running suture is the preferential method for abdominal closure. In this technique the suture is secured with an initial knot and successive tissue bites are taken. At each tissue bite, the needle is rotated through the tissue; in doing so, the suture can twist around the knot which acts as an anchor.

Hennessey, D B

2012-08-01

44

Tension of knotted surgical sutures shows tissue specific rapid loss in a rodent model  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Every surgical suture compresses the enclosed tissue with a tension that depends from the knotting force and the resistance of the tissue. The aim of this study was to identify the dynamic change of applied suture tension with regard to the tissue specific cutting reaction. Methods In rabbits we placed single polypropylene sutures (3/0 in skin, muscle, liver, stomach and small intestine. Six measurements for each single organ were determined by tension sensors for 60 minutes. We collected tissue specimens to analyse the connective tissue stability by measuring the collagen/protein content. Results We identified three phases in the process of suture loosening. The initial rapid loss of the first phase lasts only one minute. It can be regarded as cutting through damage of the tissue. The percentage of lost tension is closely related to the collagen content of the tissue (r = -0.424; p = 0.016. The second phase is characterized by a slower decrease of suture tension, reflecting a tissue specific plastic deformation. Phase 3 is characterized by a plateau representing the remaining structural stability of the tissue. The ratio of remaining tension to initial tension of phase 1 is closely related to the collagen content of the tissue (r = 0.392; p = 0.026. Conclusions Knotted non-elastic monofilament sutures rapidly loose tension. The initial phase of high tension may be narrowed by reduction of the surgeons' initial force of the sutures' elasticity to those of the tissue. Further studies have to confirm, whether reduced tissue compression and less local damage permits improved wound healing.

Klink Christian D

2011-12-01

45

21 CFR 882.4650 - Neurosurgical suture needle.  

Science.gov (United States)

...2010-04-01 false Neurosurgical suture needle. 882.4650 Section 882.4650 Food...Devices § 882.4650 Neurosurgical suture needle. (a) Identification. A neurosurgical suture needle is a needle used in suturing during...

2010-04-01

46

Experimental Studies on Mortar Using Polypropylene Fibers  

Directory of Open Access Journals (Sweden)

Full Text Available An experimental program was carried out to evaluate the properties of cement Mortar. Compressive strength test, splitting tensile strength test and the water absorption test were performed and the results were analysed statistically. Polypropylene fibers can greatly increase the properties of cement Mortar. Specimens containing fiber of 0.00%, 0.10%, 0.20% and 0.30% are prepared and tested in this work. It is demonstrated that a certain amount of fibers enhances the compressive, splitting tensile strength and the water absorption capacity of the fiber reinforced cement mortar. The Compressive strength of mortar was increased to 118.15 % at 7 days & 29.14 % at 28days and splitting tensile strength was increased by 130.30 % at 7 days & 56.15 % at 28 days.

Divyeshkumar D. Paradava*1

2014-05-01

47

Unusual sutural bones at pterion  

Directory of Open Access Journals (Sweden)

Full Text Available The existence of Wormian (sutural bones in the skull is well known. We found three unusual Wormian bones at the right pterion in an adult Indian skull. The variation noted was unilateral. This type of variation has not been reported yet.

Nayak SB

2008-08-01

48

The radiation degradation of polypropylene  

International Nuclear Information System (INIS)

Polypropylene is used extensively in the manufacture of disposable medical devices because of its superior properties. Unfortunately this polymer does not lend itself well to radiation sterilization, undergoing serious degradation which affects the mechanical properties of the polymer. In this paper the effects of radiation on the mechanical and physical properties of polypropylene are discussed. A programme of research to minimize the radiation degradation of this polymer through the addition of crosslinking agents to counteract the radiation degradation is proposed. It is furthermore proposed that a process of annealing of the irradiated polymer be investigated in order to minimize the post-irradiation degradation of the polypropylene

49

Rheological properties of polypropylene nanocomposites  

International Nuclear Information System (INIS)

In this work, composites of polypropylene with a master batch to obtain clay containing nano composites were obtained. The materials were characterized by X ray diffraction, small angle X-ray scattering and by rheological analysis. (author)

50

Polypropylene/clay nanocomposites revisited  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis is devoted to the optimization of polypropylene (PP)/clay nanocomposites preparation by trying to resolve or find alternatives to the actual limitations of producing PP/clay nanocomposites which restrain their industrial development. A large part of this work is focused on the study and optimization of functionalized polypropylenes as compatibilizers and an optimized PP-graft-maleic anhydride (PP-g-MA), having significantly higher graft content than classic PP-g-MAs, was selected....

Rousseaux, Dimitri

2010-01-01

51

The Bentong Raub Suture Zone  

Science.gov (United States)

It is proposed that the Bentong-Raub Suture Zone represents a segment of the main Devonian to Middle Triassic Palaeo-Tethys ocean, and forms the boundary between the Gondwana-derived Sibumasu and Indochina terranes. Palaeo-Tethyan oceanic ribbon-bedded cherts preserved in the suture zone range in age from Middle Devonian to Middle Permian, and mélange includes chert and limestone clasts that range in age from Lower Carboniferous to Lower Permian. This indicates that the Palaeo-Tethys opened in the Devonian, when Indochina and other Chinese blocks separated from Gondwana, and closed in the Late Triassic (Peninsular Malaysia segment). The suture zone is the result of northwards subduction of the Palaeo-Tethys ocean beneath Indochina in the Late Palaeozoic and the Triassic collision of the Sibumasu terrane with, and the underthrusting of, Indochina. Tectonostratigraphic, palaeobiogeographic and palaeomagnetic data indicate that the Sibumasu Terrane separated from Gondwana in the late Sakmarian, and then drifted rapidly northwards during the Permian-Triassic. During the Permian subduction phase, the East Malaya volcano-plutonic arc, with I-Type granitoids and intermediate to acidic volcanism, was developed on the margin of Indochina. The main structural discontinuity in Peninsular Malaysia occurs between Palaeozoic and Triassic rocks, and orogenic deformation appears to have been initiated in the Upper Permian to Lower Triassic, when Sibumasu began to collide with Indochina. During the Early to Middle Triassic, A-Type subduction and crustal thickening generated the Main Range syn- to post-orogenic granites, which were emplaced in the Late Triassic-Early Jurassic. A foredeep basin developed on the depressed margin of Sibumasu in front of the uplifted accretionary complex in which the Semanggol "Formation" rocks accumulated. The suture zone is covered by a latest Triassic, Jurassic and Cretaceous, mainly continental, red bed overlap sequence.

Metcalfe, I.

2000-12-01

52

Radiation effect on stabilized polypropylene  

International Nuclear Information System (INIS)

Radiation-induced oxidative degradation of stabilized polypropylene films using Co-60 ? irradiation at room temperature under different irradiation conditions (vacuum and oxygen) was investigated. Gas evolution, oxygen consumption, and mechanical properties were studied and analyzed quantitatively. The G values for the evolved gases during irradiation of stabilized polypropylene films under vacuum and in presence of oxygen are given. The stabilized polypropylene, irradiated at low doses under different conditions (air, oxygen, and vacuum), shows mechanical properties almost similar to those of the unirradiated one. However, at higher doses the mechanical properties were sharply decreased and deterioration was enhanced in the presence of oxygen due to the oxidative degradation. On the other hand, post-irradiation effect on the stabilized polypropylene irradiated up to 0.02 MGy under vacuum, was studied at various annealing temperatures and different storage time at room temperature. Molecular weight distribution curves for polypropylene samples irradiated in air atmosphere show that degradation of the high molecular weight chains is the predominant process in the range of irradiation doses under investigation. (author)

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The benefits of using barbed sutures with automated suturing devices in gynecologic endoscopic surgeries.  

Science.gov (United States)

Laparoscopic suturing and knot tying are some of the most difficult surgical skills to acquire, and are often times regarded as a rate-limiting step in the performance of advanced gynecologic endoscopic procedures. Automated suturing devices can significantly decrease the steep learning curve of this task but still require laparoscopic knot tying. Barbed sutures offer several advantages including rapid, consistent wound closure with even distribution of tension across the wound, the suture holds tension on its own, the need for knot tying with associated issues related to suture tensile strength and knot security is eliminated, and suturing time is decreased. Use of a barbed suture with an automated suturing device can offer many advantages to both the novice and the experienced surgeon, including increased efficiency, more uniform wound closure, and the ability to perform a laparoscopic continuous running stitch without the need for intracorporeal knot tying. PMID:24081852

Hart, Stuart; Sobolewski, Craig J

2013-09-01

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Suture needles in Oral Surgery: Alterations depending on the type and number of sutures  

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This study examined whether the number and type of sutures used in oral surgery influence two ad hoc variables (incision plane and displaced area), which are two variables related to whether the suture needle is suitable for the task. Seventy-five TB-15 needles were studied, which were used to suture between zero and three mucosa and/subperiosteal sutures, producing 15 groups with 5 needles in each one. The incision plane and displaced area were measured for each group, which are ...

Torres-lagares, Daniel; Barranco-piedra, Sebastian; Rodri?guez-caballero, Angela; Serrera-figallo, Mari?a-angeles; Segura-egea, Juan-jose?; Gutie?rrez-pe?rez, Jose?-luis

2012-01-01

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Transoral Mucosal Excision Sutured Gastroplasty  

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Introduction. An outpatient transoral endoscopic procedure for gastroesophageal reflux disease (GERD) and obesity would be appealing if safe, effective, and durable. We present the first in human experience with a new system. Methods. Eight patients with GERD (3) and obesity (5) were selected according to a preapproved study protocol. All GERD patients had preprocedure manometry and pH monitoring to document GERD as well as quality of life and symptom questionnaires. Obese patients (body mass index >35) underwent a psychological evaluation and tests for comorbidities. Under general anesthesia, a procedure was performed at the gastroesophageal junction including mucosal excision, suturing of the excision beds for apposition, and suture knotting. Results. One patient with micrognathia could not undergo the required preprocedural passage of a 60 F dilator and was excluded. The first 2 GERD patients had incomplete procedures due to instrument malfunction. The subsequent 5 subjects had a successfully completed procedure. Four patients were treated for obesity and had an average excess weight loss of 30.3% at 2-year follow-up. Of these patients, one had an 8-mm outlet at the end of the procedure recognized on video review—a correctable error—and another vomited multiple times postoperatively and loosened the gastroplasty sutures. The treated GERD patient had resolution of reflux-related symptoms and is off all antisecretory medications at 2-year follow-up. Her DeMeester score was 8.9 at 24 months. Conclusion. The initial human clinical experience showed promising results for effective and safe GERD and obesity therapy. PMID:24623807

Legner, Andras; Altorjay, Aron; Juhasz, Arpad; Stadlhuber, Rudolph; Reich, Viktor; Hunt, Brandon; Rothstein, Richard

2014-01-01

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Suturing techniques and postoperative management in penetrating keratoplasty in the United Kingdom  

Directory of Open Access Journals (Sweden)

Full Text Available Richard MH Lee,1 Fook Chang Lam,1 Tassos Georgiou,1 Bobby Paul,1 Kong Yong Then,1 Ioannis Mavrikakis,1 Venkata S Avadhanam,1 Christopher SC Liu1,21Sussex Eye Hospital, Brighton, United Kingdom; 2Tongdean Eye Clinic, Hove, United KingdomAims: To report on the suturing techniques and aspects of postoperative management in penetrating keratoplasty in the United Kingdom.Methods: A postal questionnaire was sent to 137 ophthalmic consultants identified from a Royal College of Ophthalmology database as having a special interest in anterior segment surgery. The questionnaire surveyed surgeon preferences for surgical and suturing technique for penetrating keratoplasty surgery, and the postoperative care of corneal grafts.Results: In all, 68% of questionnaires were completed and returned: 73% of respondents used a Flieringa ring or equivalent, 94% routinely used cardinal sutures, with 50.5% removing them at the end of the procedure. The most common suturing technique for routine penetrating keratoplasty was a single continuous suture (35%. In these cases, a 10/0 nylon suture was used by 89%. Sixty-six percent changed their technique in high-risk cases, 52% used a 3-1-1 knot, and 75% made a distinction between a reef and granny knot, with 76% using a reef. Thirty percent buried the knots within the donor material, and 29% within the host tissue. Twenty-five percent had no routine time for graft suture removal, but 41% removed them between 1 and 2 years post-surgery. After suture removal, 98% used steroids and 88% used topical antibiotics. Thirty-four percent stopped topical steroids before suture removal, with 38% stopping topical steroids more than 3 months prior to suture removal.Conclusion: This survey demonstrates that there is considerable variation in suturing techniques and postoperative care for penetrating keratoplasty. These significant variations in practice need to be considered when interpreting outcomes and research.Keywords: corneal graft, penetrating keratoplasty, anterior segment surgery, cornea, corneal surgery, corneal transplantation

Lee RM

2012-08-01

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21 CFR 878.4495 - Stainless steel suture.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Stainless steel suture. 878.4495 Section 878.4495...Surgical Devices § 878.4495 Stainless steel suture. (a) Identification. A stainless steel suture is a needled or unneedled...

2010-04-01

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21 CFR 878.4495 - Stainless steel suture.  

Science.gov (United States)

...Surgical Devices § 878.4495 Stainless steel suture. (a) Identification. A stainless steel suture is a needled or unneedled nonabsorbable surgical suture composed of 316L stainless steel, in USP sizes 12-0 through 10,...

2010-04-01

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Anastomose arterial com fio de polidioxanona e fio de polipropileno. Estudo comparativo em cães Arterial anastomose with polydioxanone and polypropilene suture. Comparative study in dogs  

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Full Text Available Este estudo teve por objetivo comparar os efeitos do fio absorvível de polidioxanona com o fio inabsorvível de polipropileno, em anastomoses término-terminais, em artérias femorais de cães. Foram utilizados 20 cães, separados em dois grupos, para observação no 7º e no 30º dia de pós-operatório. Cada cão teve suas artérias femorais seccionadas e aproximadas em um lado com pontos separados de fio de polidioxanona 6-0, e no lado contralateral com o fio de polipropileno 6-0. A escolha do fio foi feita por sorteio, totalizando 40 anastomoses. Para análise estatística dos resultados aplicaram-se os testes de Fisher, Mac Nemar, Wilcoxon, Mann-Witney e o teste T de Student (a ? 0,05. Nas avaliações clínicas não foram observadas diferenças significantes entre os fios utilizados. Os resultados obtidos nas avaliações arteriográfica e macroscópica dos segmentos arteriais foram semelhantes, assim como na análise histológica morfológica. Na análise histológica morfométrica o fio de polipropileno apresentou número de células gigantes de corpo estranho significativamente maior que o fio de polidioxanona aos 7 e 30 dias de pós-operatório. Os resultados nos permitem concluir que, apesar da maior reação de corpo estranho observada com o fio de polipropileno, o fio de polidioxanona apresentou resultados semelhantes ao fio de polipropileno, em anastomoses arteriais em cães.The objetive of this study was to compare the effects of the absorbable polidioxanone suture to the nonabsorbable polypropylene suture, in end-to-end anastomoses, using dog’s femoral arteries. Twenty dogs were separated in two groups for observation on the 7th and 30th post-operatory day. Each dog had its femoral arteries seccioned and then aproximated one side with separate stitches of polidioxanone 6-0 suture, and the other side with polypropylene 6-0 suture. For the statistical studies Fisher, Mac nemar, Wilsoxon, Mann-Witney and T of Student tests (a ? 0,05 were carried out. No significant differences were observed between the sutures employed in clinical evolution. The results obtained in the arteriographic and macroscopic avaliation were similar, as well as the morphological histologic analysis. In the morfometric histologic analysis the polypropylene suture showed a significantly higher number of foreign body giant cells reaction, comparing to the polydioxanone suture on the 7th or 30th post-operatory day. The results allow us to conclude that, in spit of the higher reaction of foreign body observed with the polypropilene suture, the polydioxanone suture showed similar results in dog’s arterial anastomoses.

Eloísa de Brida Tormena

2002-03-01

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Mesenchymal stem cell-coated sutures enhance collagen depositions in sutured tissues.  

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Sutures are commonly used for surgical procedures and new sutures are being developed to improve wound healing. In the past decade, it has been extensively shown that mesenchymal stem cells (MSCs) have a wound healing potential. To benefit the overall wound healing process, we aimed to analyze the usage of pretreated sutures for improving the implantation of MSCs in the tissues. Our results firstly showed that suture pretreatments with gelatin, poly-L-lysine, and NaOH improved the adhesive strength of MSCs to sutures. These cells remained surrounding the sutured tissue and no significant phenotypic changes were found in those cells cultured onto pretreated sutures. In vivo experiments showed that the implantation of MSCs by suturing increases the collagen content in the sutured tissue. Moreover, proteomics analysis of secreted proteins showed that collagen alpha-1(I) chain was the most abundant collagen found. To our knowledge, this is the first report that aimed to improve the implantation of MSCs in tissue by suture pretreatments. Moreover, in vivo experiments suggest that MSC-coated sutures may enhance wound healing and tissue remodeling through the release of different collagen types being applicable for those patients that tend to have difficulty healing. PMID:24635176

Casado, Javier G; Blazquez, Rebeca; Jorge, Inmaculada; Alvarez, Veronica; Gomez-Mauricio, Guadalupe; Ortega-Muñoz, Mariano; Vazquez, Jesus; Sanchez-Margallo, Francisco M

2014-01-01

 
 
 
 
61

The double loop mattress suture.  

Science.gov (United States)

An interrupted stitch type with favorable tissue characteristics will reduce local wound complications. We describe a novel high-strength, low-tension repair for the interrupted closure of skin, cartilage, and muscle, the double loop mattress stitch, and compare it experimentally with other interrupted closure methods. The performance of the double loop mattress technique in porcine cartilage and skeletal muscle is compared with the simple, mattress, and loop mattress interrupted sutures in both a novel porcine loading chamber and mechanical model. Wound apposition is assessed by electron microscopy. The performance of the double loop mattress in vivo was confirmed using a series of 805 pediatric laparotomies/laparoscopies. The double loop mattress suture is 3.5 times stronger than the loop mattress in muscle and 1.6 times stronger in cartilage (p???0.001). Additionally, the double loop mattress reduces tissue tension by 66% compared with just 53% for the loop mattress (p???0.001). Wound gapping is equal, and wound eversion appears significantly improved (p???0.001) compared with the loop mattress in vitro. In vivo, the double loop mattress performs as well as the loop mattress and significantly better than the mattress stitch in assessments of wound eversion and dehiscence. There were no episodes of stitch extrusion in our series of patients. The mechanical advantage of its intrinsic pulley arrangement gives the double loop mattress its favorable properties. Wound dehiscence is reduced because this stitch type is stronger and exerts less tension on the tissue than the mattress stitch. We advocate the use of this novel stitch wherever a high-strength, low-tension repair is required. These properties will enhance wound repair, and its application will be useful to surgeons of all disciplines. PMID:24698436

Biddlestone, John; Samuel, Madan; Creagh, Terry; Ahmad, Tariq

2014-01-01

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Endoscopic dacryocystorhinostomy with flap suturing.  

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Multiple reports have demonstrated the efficacy of endoscopic dacryocystorhinostomy (DCR). However the results of the same have varied from centre to centre. Many still regard external DCR as the gold standard. To describe an endoscopic DCR technique which anatomically simulates an external DCR and assess its results. Prospective, nonrandomized and noncomparative interventional case series. Clinical charts of patients with nasolacrimal duct obstruction based on symptomatic, clinical and radiological basis were included in the study. All surgeries were done endonasally using standard operative technique. The modification in the standard technique included creating a wide exposure of the lacrimal sac, incising the sac and the suturing the medial wall of the lacrimal sac with the lateral nasal wall. The same was achieved by using either vascular clips or 5.0 vicryl sutures. Twenty (11 females and 9 males) were included in the study. The average age of the patients was 56.86 years old (range 27-85 years old). The main presenting symptom was epiphora and 1 patient with mucocele. Successful outcome was measured in terms of relief of sympto anatomical patency assessed by sac syringing and nasal endoscopy showing a wide patent lumen. A primary success rate of 95% and ultimate rate of 100% was achieved in the cases with a nasolacrimal duct (NLD) block while an overall success rate of 82.6% was noted when the cases with NLD block and common canalicular block were considered together. Endoscopic DCR can now easily replace external DCR as a standard. It is not only minimally invasive, but has minimal complications and using this technique, we have been able to achieve very high success rates. PMID:24427653

Kirtane, Milind V; Lall, Abhineet; Chavan, Kashmira; Satwalekar, Dhruv

2013-08-01

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Terminal Area Simulation System User's Guide - Version 10.0  

Science.gov (United States)

The Terminal Area Simulation System (TASS) is a three-dimensional, time-dependent, large eddy simulation model that has been developed for studies of wake vortex and weather hazards to aviation, along with other atmospheric turbulence, and cloud-scale weather phenomenology. This document describes the source code for TASS version 10.0 and provides users with needed documentation to run the model. The source code is programed in Fortran language and is formulated to take advantage of vector and efficient multi-processor scaling for execution on massively-parallel supercomputer clusters. The code contains different initialization modules allowing the study of aircraft wake vortex interaction with the atmosphere and ground, atmospheric turbulence, atmospheric boundary layers, precipitating convective clouds, hail storms, gust fronts, microburst windshear, supercell and mesoscale convective systems, tornadic storms, and ring vortices. The model is able to operate in either two- or three-dimensions with equations numerically formulated on a Cartesian grid. The primary output from the TASS is time-dependent domain fields generated by the prognostic equations and diagnosed variables. This document will enable a user to understand the general logic of TASS, and will show how to configure and initialize the model domain. Also described are the formats of the input and output files, as well as the parameters that control the input and output.

Switzer, George F.; Proctor, Fred H.

2014-01-01

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Fracture Toughness Studies of Polypropylene- Clay Nanocomposites and Glass Fibre Reinfoerced Polypropylene Composites  

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In this paper, a comparative study on the fracture toughness of woven glass fibre reinforced polypropylene, chopped glass fibre reinforced polypropylene and nanoclay filled polypropylene composites is presented. Nanoclays (Cloisite 15A) of 1 wt. % to 5 wt. % were filled in polypropylene (PP) matrix and they were subjected to fracture toughness stu-dies. The specimen with 5 wt. % nanoclay showed 1.75 times and 3 times improvement in critical stress intensity factor (KIC) and strain energy rele...

Ramsaroop, A.; Kanny, K.; Mohan, T. P.

2010-01-01

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[Experimental evaluation, in vitro and in vivo, of the risk of infection related to the use of the most common surgical sutures].  

Science.gov (United States)

Many parameters contribute to surgical infections. Of these, surgical sutures with their chemical and physical characteristics like tissue and cell reaction degree and bacterial adhesion, play an important role. Cell vitality, bacterial adhesion, cell reaction degree were tested "in vitro" and tissue reaction with an "in vivo" model on: plain catgut, silk, polyglycolic acid, polyglactin 910, polyglyconate, polypropylene and nylon. Vitality cell test did not reveal any cytotoxicity; bacterial adhesion showed a lower adhesion degree to synthetic materials; cell reaction showed an increase in soluble receptor (sIL 2R) values in all materials except catgut. Tissue reaction was higher for resorbable sutures, and lower for nylon. These results suggest that special attention should be paid to the choice of suture materials. PMID:1289753

Giardino, R; Rocca, M; Fini, M; Buscaroli, S; Giavaresi, G; Nicoli Aldini, N; Bacchini, P; Bertoni, F

1992-12-01

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Effects of primary suture and fib sealant on hemostasis and liver regeneration in an experimental liver injury  

Science.gov (United States)

AIM: To investigate the effects of fib sealant on hemostasis and liver regeneration and intra-abdominal adhesions in an experimental liver injury. METHODS: Thirty-six Wistar rats were randomly divided into primary suture group (n = 15), fib sealant group (n = 15) and control group (n = 6). A wedge resection was performed on the left lobe of the liver. In primary suture group, liver was sutured using polypropylene material, while fib glue was administrated on the liver surface in fib sealant group. RESULTS: More intra-abdominal adhesions were observed in the primary suture group compared to the fib sealant group on 3rd (2.50 ± 0.5 vs 0.25 ± 0.5, P = 0.015), 10th (2.75 ± 0.5 vs 0.50 ± 0.6, P = 0.06) and 20th (1.75 ± 0.5 vs 0.70 ± 0.5, P = 0.015) postoperative days. Histopathological scores were better in the fib sealant group in comparison with the primary suture group on 3rd (8.75 ± 0.5 vs 6.75 ± 0.5, P = 0.006), 10th (7.50 ± 1.0 vs 5.5 ± 0.6, P = 0.021) and 20th (6.40 ± 1.7 vs 3.20 ± 1.6, P = 0.025) postoperative days. CONCLUSION: Out data suggest that fib sealant is preferred over primary suture in appropriate cases including liver trauma since it causes less intra-abdominal adhesions while allowing shorter hemostasis time as assessed in experimental liver trauma. PMID:18176966

Demirel, Arif Hakan; Basar, Ozgur Taylan; Ongoren, Ali Ulvi; Bayram, Erkut; Kisakurek, Mustafa

2008-01-01

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Effects of primary suture and fib sealant on hemostasis and liver regeneration in an experimental liver injury  

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Full Text Available AIM: To investigate the effects of fib sealant on hemostasis and liver regeneration and intra-abdominal adhesions in an experimental liver injury.METHODS: Thirty-six Wistar rats were randomly divided into primary suture group (n = 15, fib sealant group (n = 15 and control group (n = 6. A wedge resection was performed on the left lobe of the liver. In primary suture group, liver was sutured using polypropylene material, while fib glue was administrated on the liver surface in fib sealant group.RESULTS: More intra-abdominal adhesions were observed in the primary suture group compared to the fib sealant group on 3rd (2.50 ± 0.5 vs 0.25 ± 0.5, P = 0.015, 10th (2.75 ± 0.5 vs 0.50 ± 0.6, P = 0.06 and 20th (1.75 ± 0.5 vs 0.70 ± 0.5, P = 0.015 postoperative days. Histopathological scores were better in the fib sealant group in comparison with the primary suture group on 3rd (8.75 ± 0.5 vs 6.75 ± 0.5, P = 0.006, 10th (7.50 ± 1.0 vs 5.5 ± 0.6, P = 0.021 and 20th (6.40 ± 1.7 vs 3.20 ± 1.6, P = 0.025 postoperative days.CONCLUSION: Out data suggest that fib sealant is preferred over primary suture in appropriate cases including liver trauma since it causes less intra-abdominal adhesions while allowing shorter hemostasis time as assessed in experimental liver trauma.

Arif Hakan Demirel, Ozgur Taylan Basar, Ali Ulvi Ongoren, Erkut Bayram, Mustafa Kisakurek

2008-01-01

68

Evaluation of an improved suture for cataract surgery.  

Science.gov (United States)

An improved synthetic absorbable suture for ophthalmic surgery, 8-0 Dexon "S" polyglycolic acid, was evaluated in 25 cataract extractions and, in 5 cases, compared with 8-0 Vicryl polyglactin sutures. Dexon "S" sutures caused less tissue drag than Vicryl sutures; Vicryl was more easily knotted. With respect to handling, knotting, tissue drag, absorption, and postoperative complications, the improved Dexon suture was found to be well suited for use in cataract surgery. PMID:434745

Sherman, S E

1979-02-01

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Functional implications of squamosal suture size in paranthropus boisei.  

Science.gov (United States)

It has been hypothesized that the extensively overlapping temporal and parietal bones of the squamosal sutures in Paranthropus boisei are adaptations for withstanding loads associated with feeding. Finite element analysis (FEA) was used to investigate the biomechanical effects of suture size (i.e., the area of overlap between the temporal and parietal bones) on stress, strain energy, and strain ratio in the squamosal sutures of Pan troglodytes and P. boisei (specimen OH 5) during biting. Finite element models (FEMs) of OH 5 and a P. troglodytes cranium were constructed from CT scans. These models contain sutures that approximate the actual suture sizes preserved in both crania. The FEM of Pan was then modified to create two additional FEMs with squamosal sutures that are 50% smaller and 25% larger than those in the original model. Comparisons among the models test the effect of suture size on the structural integrity of the squamosal suture as the temporal squama and parietal bone move relative to each other during simulated premolar biting. Results indicate that with increasing suture size there is a decreased risk of suture failure, and that maximum stress values in the OH 5 suture were favorable compared to values in the Pan model with the normal suture size. Strain ratios suggest that shear is an important strain regime in the squamosal suture. This study is consistent with the hypothesis that larger sutures help reduce the likelihood of suture failure under high biting loads. PMID:24242913

Dzialo, Christine; Wood, Sarah A; Berthaume, Michael; Smith, Amanda; Dumont, Elizabeth R; Benazzi, Stefano; Weber, Gerhard W; Strait, David S; Grosse, Ian R

2014-02-01

70

Pullout strength of suture anchors in comparison with transosseous sutures for rotator cuff repair.  

Science.gov (United States)

Suture anchors are increasingly gaining importance in rotator cuff surgery. This means they will be gradually replacing transosseous sutures. The purpose of this study was to compare the stability of transosseous sutures with different suture anchors with regard to their pullout strength depending on bone density. By means of bone densitometry (CT scans), two groups of human humeral head specimens were determined: a healthy and a osteopenic bone group. Following anchor systems were being tested: SPIRALOK 5.0 mm (resorbable, DePuy Mitek), Super Revo 5 mm (titanium, Linvatec), UltraSorb (resorbable, Linvatec) and the double U-sutures with Orthocord USP 2 (partly resorbable, DePuy Mitek) and Ethibond Excel 2 (non-resorbable, Ethicon). The suture anchors/double U-sutures were inserted in the greater tuberosity 12 times. An electromechanical testing machine was used for cyclic loading with power increasing in stages. We recorded the ultimate failure loads, the system displacements and the modes of failure. The suture anchors tended to bring about higher ultimate failure loads than the transosseous double U-sutures. This difference was significant in the comparison of the Ethibond suture and the SPIRALOK 5.0 mm-both in healthy and osteopenic bone. Both the suture materials and the SPIRALOK 5.0 mm showed a significant difference in pullout strength on either healthy or osteopenic bone; the titanium anchor SuperRevo 5 mm and the tilting anchor UltraSorb did not show any significant difference in healthy or osteopenic bone. There was no significant difference concerning system displacement (healthy and osteopenic bone) between the five anchor systems tested. The pullout strength of transosseous sutures is neither on healthy nor on osteopenic bone higher than that of suture anchors. Therefore, even osteopenic bone does not constitute a valid reason for the surgeon to perform open surgery by means of transosseous sutures. The choice of sutures in osteopenic bone is of little consequence anyway since it is mostly the bone itself which is the limiting factor. PMID:18193198

Pietschmann, Matthias F; Fröhlich, Valerie; Ficklscherer, Andreas; Hausdorf, Jörg; Utzschneider, Sandra; Jansson, Volkmar; Müller, Peter E

2008-05-01

71

Radiation stabilization of polypropylene by phenolic stabilizers  

International Nuclear Information System (INIS)

The radiation stability of polypropylene stabilized with two phenolic stabilizers and synergistic behaviour of these stabilizers have been investigated. The variation of carbonyl index and mechanical properties of stabilized and unstabilized polypropylene has been followed for 6 months after irradiation at 25 kGy. The extent of chain scission has been followed by measuring the change in apparent viscosity. (author)

72

Radiation stabilization of polypropylene by phenolic stabilizers  

Energy Technology Data Exchange (ETDEWEB)

The radiation stability of polypropylene stabilized with two phenolic stabilizers and synergistic behaviour of these stabilizers have been investigated. The variation of carbonyl index and mechanical properties of stabilized and unstabilized polypropylene has been followed for 6 months after irradiation at 25 kGy. The extent of chain scission has been followed by measuring the change in apparent viscosity. (author).

Hassanpour, S.; Yousefi, A. (Atomic Energy Organization of Iran, Teheran (Iran, Islamic Republic of))

73

Mechanical performance of gamma irradiated surgical sutures  

International Nuclear Information System (INIS)

Surgical sutures are medical devices made of natural or synthetic polymeric materials that, due to its end-use, have to be sterilized. Historically, the sterilization by heat or using ethylene oxide had presented so numerous drawbacks that today the non-pollutant radiation sterilization has become a well established sterilization process, that brings, environmental, technical, and economical advantages. The amount of irradiation doses required for sterilization of health care products is 25 kGy in most instances to achieve the necessary sterility assurance level. As high energy radiation produces modifications in the molecular structure of organic materials with changes in its mechanical properties, the aim of this work was to evaluate the mechanical behavior of surgical sutures under irradiation. Silk, polyamide and catgut sutures were gamma irradiated up to doses of 50 kGy in an industrial irradiation sterilization plant. Afterwards, these sutures were mechanical tested for tensile strength under knot following the specifications of the NBR13904 draft standard, using the CTRD-INSTRON at IPEN. The mechanical lab results show that sutures made of Silk and Polyamide do not present any change in their mechanical performance up to the dose of 50 kGy. On the other hand, Catgut present mechanical stability up to 30 kGy and afterwards, a slight decrease in its tensile strength was detected. (author)

74

Cauterization technique for suture erosion in transscleralfixation of intraocular lenses  

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Full Text Available Transscleral suturing is a commonly applied technique to fix intraocular implants in the sulcus. A major problem after transscleral implantation is suture erosion that normally happens in the late post-surgery period and may result in an increased incidence of endophthalmitis. Here we describe an original cauterization method by using a glass rod to melt the exposed suture end without damaging the suture knot in the sclera to avoid suture exposure in sclera-fixed IOL implantation. This is a simple, quick and effective technique that can be performed without conjunctiva incisions and will help to reduce suture erosion related complications.

Xu-Ting Hu

2013-12-01

75

Scapholunate ligament repair using suture anchors.  

Science.gov (United States)

Background. This article describes the surgical repair of scapholunate ligament injury using Mitek suture anchors. Material and methods. 3 patients with neglected injuries of the scapholunate ligament were operated from 8 weeks to 5 months after trauma. The authors found that using the Mitek anchor suture simplifies the operative technique, obviates the technical difficulties involved in guiding the tendon through the bone tunnel, and reduces the possibility of the complications seen in the standard ligament repair techniques. Results and Conclusions. The operative technique used in the Clinic of Hand Surgery at the Medical University of Gdansk combines reduction of the displaced scaphoid bone from the dorsal approach and temporary scaphocapitate fixation with K wires, bringing the ruptured ligament closer with capsulodesis using Mitek suture anchors. PMID:17603433

Baczkowski, Bogus?aw; Lorczy?ski, Adam; Kabu?a, Jaros?aw; Camilleri, Rafa?

2006-04-28

76

Transcutaneous lower blepharoplasty, painless suture removal.  

Science.gov (United States)

Despite being referred to as one of the more challenging procedures in plastic surgery, lower blepharoplasty is one of the most commonly requested and performed aesthetic procedures.Our experience, from February 2007 to March 2012, is based on 214 transcutaneous lower blepharoplasty procedures in which the skin flap was sutured by means of the epidermal-dermal U stitch, a new, simple, and reliable method. Patients were followed up for a mean period ranging from 7 to 70 months. To our knowledge, the literature proposes a single-stitch closure or continuous suture in transcutaneous lower blepharoplasty using nylon or silk 4-5-0 to close the skin incision (1-3-5). According to our experience before 2007 based on patients' reports, single-stitch subciliary suture removal is a source of stress for the patient that causes anxiety, discomfort, and pain.Thus, in February 2007, following transepithelial lower blepharoplasty, we started using a new, simple way to suture the subciliary skin flap adopting the epidermal-dermal U nylon 5-0 stitch to avoid any discomfort and drastically reduce the level of anxiety and pain at the time of suture removal. According to our experience, the healing of the wound does not require any subsequent scar revision resulting from healing defects or pathological scar tissue; the complication rate in our series is in keeping with that reported by other authors in the literature.In conclusion, our experience indicates that the suture technique we describe is an easily reproducible, rapid, discomfort-free, and painless means of removing stitches. PMID:24036781

De Vita, Roy; Buccheri, Ernesto Maria

2013-01-01

77

Flexor Tenorrhaphy Using Absorbable Suture Materials  

Directory of Open Access Journals (Sweden)

Full Text Available Background Nonabsorbable sutures are favorable for repairing flexor tendons. However,absorbable sutures have performed favorably in an animal model.Methods Two-strand sutures using the interlocking modified Kessler method with polydioxanoneabsorbable sutures 4-0 were used to repair completely ruptured flexor tendons in 55 fingersfrom 41 consecutive patients. The medical records of average 42 follow up weeks were analyzedretrospectively. The data analyzed using the chi-squared test, and Fisher’s exact test was used forpostoperative complications. The results were compared with those of other studies.Results Among the index, middle, ring, and little fingers were injured in 9, 17, 16, and13 fingers, respectively. The injury levels varied from zone 1 to 5. Of the 55 digits in ourstudy, there were 26 (47% isolated flexor digitorum profundus (FDP injuries and 29 (53%combined FDP and with flexor digitorum superficialis injuries. Pulley repair was also conducted.Concomitant injuries of blood vessels and nerves were found in 17 patients (23 fingers; nerveinjuries occurred in 5 patients (10 fingers. Two patients had ruptures (3.6%, and one patienthad two adhesions (3.6%. Using the original Strickland criteria, all the patients were assessedto be excellent or good. Also, fibrosis and long-term foreign body tissue reactions such as stitchgranuloma were less likely occurred in our study. Compared to the Cullen’s report that usednonabsorbable sutures, there was no significant difference in the rupture or adhesion rates.Conclusions Therefore, this study suggests that appropriate absorbable core sutures can beused safely for flexor tendon repairs.

Hyung Joo Kang

2012-07-01

78

Prolene monofilament suture in Boston Keratoprosthesis surgery  

Science.gov (United States)

Summary Toxic reaction to nylon following uncomplicated cataract surgery and vitrectomy has been documented in the literature. We report the case of an aniridic patient with a known adverse reaction to nylon in whom Prolene suture was used in Boston Keratoprosthesis type 1 (KPro) surgery. During follow-up the cornea was checked for signs of inflammation and toxic reaction; at last follow-up (18 months) the patient showed no signs of complications due to Prolene. Our study suggests that Prolene suture may be used as an alternative to nylon in Boston KPro surgery in patients with a history of nylon toxicity. PMID:23362386

Kyrillos,, Ralph; Harissi-Dagher, Mona

2011-01-01

79

Using the argon laser to cut corneoscleral sutures.  

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The Coherent 900 argon blue-green laser can be used to cut pigmented corneoscleral sutures without damage to the overlying tissue. This is useful in tight corneoscleral sutures causing undue corneal astigmatism. PMID:6706822

Thompson, F B

1984-01-01

80

Multiaxial yield behaviour of polypropylene  

Science.gov (United States)

In order to characterize the yield behavior of polypropylene as a function of pressure and to verify the applicability of the Drucker-Prager yield function, various tests were conducted to cover a wide range of stress states from uniaxial tension and compression to multiaxial tension and confined compression. Tests were performed below and above the glass transition temperature, to study the combined effect of pressure and temperature. The pressure sensitivity coefficient as an intrinsic material parameter was determined as a function of temperature. Increasing pressure sensitivity values were found with increasing temperature, which can be related to the change in the free volume and thus, to the enhanced molecular mobility. A best-fit Drucker-Prager yield function was applied to the experimental yield stresses and an average error between the predictions and the measurements of 7 % was obtained.

Jerabek, M.; Tscharnuter, D.; Major, Z.; Ravi-Chandar, K.; Lang, R.

2010-06-01

 
 
 
 
81

A simple device for loading radioactive seeds into absorbable sutures  

International Nuclear Information System (INIS)

Radioactive I-125 seeds that are loaded into absorbable sutures are convenient for permanent or removable interstitial-implantation. A simple device for loading radioactive seeds into commercially available sutures is described. This loader permits fast placement of seeds in the suture with minimal exposure to the involed personnel. Variable spacing is accomplished either by absorbable spacers or by minor manipulation of the loaded suture

82

Vibrational overtone in crystalline isotactic polypropylene  

International Nuclear Information System (INIS)

Crystalline isotactic polypropylene is subjected to high but non-hydrostatic pressures and the Raman Spectra analyzed. There is evidence that the band at 2725 cm-1 is an overtone of the 1376 cm-1 band

83

Mechanical similarities observed between polypropylene gels and molten polypropylenes  

Science.gov (United States)

The gelation of syndiotactic and isotactic polypropylenes (sPP and iPP) was found when PPs were dissolved in 1,2,3,4-tetrahydronaphthalene (tetralin). Interestingly, it was found that the storage modulus of sPP-gel became higher than that of iPP-gel when PPs were dissolved in tetralin at low PP concentration (40 wt%). The result was distinctly different from the result of the neat PPs without solvent, as it is widely known that the modulus of sPP is significantly lower than that of iPP. Moreover, by measuring the storage moduli of solid sPP and iPP as a function of temperature, it was found that, above the melting points of PP, the storage modulus of sPP became higher than that of iPP, which was similar to the behavior of the storage modulus observed in the dilute PP-gels. Such mechanical similarity between PP-gels and PP-melts was also observed within iPP samples with different molecular weights. From these experimental results, it was considered that the amorphous phase of PP had profound influence on the mechanical properties of PP-gels at low PP concentration (40 wt%), while the crystalline phase of PP had a major impact on the mechanical properties of PP-gels at relatively higher PP concentration (40 wt%).

Ouchi, Tetsu; Yamazaki, Misuzu; Hotta, Atsushi

2013-03-01

84

A temporary nontoxic lubricant for a synthetic absorbable suture.  

Science.gov (United States)

Synthetic absorbable sutures have been coated with lubricants to improve their handling characteristics. A unique surfactant, poloxamer 188, has been used to coat the surface of the polyglycolic acid sutures. This lubricant was chosen because it does not damage the tissues defenses of the host and invite infection. Since poloxamer 188 is readily soluble in aqueous solutions, it is rapidly absorbed in the tissue environment resulting in an uncoated suture that displays increased knot security. The coating of polyglactin 910 is also minimally reactive in tissues and does not damage tissue defense. In contrast with the coated polyglycolic acid sutures, the knot security of the coated polyglactin 910 sutures is not altered by exposure to an aqueous environment or implantation. The increased knot security of the coated polyglycolic acid suture after implantation is considered to be a distinct clinical advantage over that of the coated polyglactin 910 sutures. PMID:3541257

Rodeheaver, G T; Foresman, P A; Brazda, M T; Edlich, R F

1987-01-01

85

Knotting and handling characteristics of coated synthetic absorbable sutures.  

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The purpose of this study was to evaluate the knotting and handling characteristics of the new coated synthetic absorbable sutures. When compared to the coated polyglactin 910 sutures, the coated polyglycolic acid sutures displayed a lower coefficient of friction, encountered less tissue drag forces, and exhibited less flexural rigidity. In the case of sizes O, 2-O, and 3-O coated polyglycolic sutures, knot security was achieved with one less throw than with similar sizes of coated polyglactin 910 sutures. On the basis of these comprehensive mechanical performance tests, the knotting and handling characteristics of the coated polyglycolic acid sutures were judged to be superior to that of the coated polyglactin 910 sutures. PMID:6317984

Rodeheaver, G T; Thacker, J G; Owen, J; Strauss, M; Masterson, T; Edlich, R F

1983-12-01

86

Argon plasma irradiation of polypropylene  

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Polypropylene samples were exposed to argon plasma discharge and the changes of the PP surface properties were studied by different methods. Surface wettability was derived from contact angle measured by standard goniometry and chemical structure of the plasma modified PP was studied using X-ray photoelectron spectroscopy (XPS) and by Rutherford backscattering spectroscopy (RBS), surface morphology and roughness of samples using AFM. Zeta potential of pristine and modified PP was determined with the SurPASS. The presence of incorporated oxygen in the PP surface layer, about 60 nm thick, was observed in RBS spectra. Oxygen concentration is a decreasing function of the depth. With progressing aging time the oxygen concentration on the PP surface decreases. Plasma treatment results in a rapid decrease of the contact angle, which increases again with increasing aging time. In XPS measurement the oxygen containing structures, created by the plasma treatment, were found on the very surface of the modified PP and the zeta potential being changed too. The significant difference in zeta potential between pristine and plasma treated PP clearly indicates that the plasma treatment leads to a more hydrophilic PP surface.

Slepicka, P., E-mail: petr.slepicka@vscht.c [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic); Vasina, A. [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic); Kolska, Z. [J.E. Purkyne University, Department of Chemistry, 40096 Usti Nad Labem (Czech Republic); Luxbacher, T. [Anton Paar GmbH, 8054 Graz (Austria); Malinsky, P.; Mackova, A. [Nuclear Physics Institute of Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic)

2010-06-15

87

Aksa plans polypropylene joint venture  

International Nuclear Information System (INIS)

Turkish acrylic fiber maker Aksa (Yalova), part of the Akkok textile conglomerate, is studying construction of a world-scale polypropylene (PP) plant as part of its diversification plans. The company says it is engaged in discussions with three 'multinations in the PP business' on the possibility of a joint venture. One of the firms is understood to be Amoco. Aksa is looking at three possible locations for the 100,000 m.t.-150,000 m.t./year plant: Yalova, near Istanbul, where its existing plants are located; Zonguldak, on the Black Sea coast; and within one of the existing complexes or a new site belonging to state-owned Petkim. Aksa has not yet discussed that option with Petkim, which recently received approval to build a $2.5-billion petrochemical complex. The Aksa PP plant would cost about $100 million and would use propylene from world markets. The onstream date depends on Aksa's ability to link up with a foreign partner, but it hopes to complete the unit within three years. Turkey has only one PP plant, a 65,000-m.t./year Petkim unit at Aliaga. The domestic market is currently two to three times that amount and is growing. Petkim also plans a 200,000-m.t./year PP plant as part of its new complex

88

Squamosal suture craniosynostosis in Muenke syndrome.  

Science.gov (United States)

Muenke syndrome caused by point mutation (C749G) in the FGFR3 gene affects 1 in 30,000 newborns and accounts for 25% to 30% of genetic causes of craniosynostosis. Anomalies in patients with Muenke syndrome include craniosynostosis, hypertelorism, sensorineural hearing loss, and developmental delay, among others. Most craniosynostoses in patients with Muenke syndrome involve bicoronal suture fusion. This article reports, for the first time, the existence of squamosal craniosynostosis in patients with Muenke syndrome. PMID:24448525

Doumit, Gaby D; Sidaoui, Joseph; Meisler, Eileen; Papay, Frank A

2014-03-01

89

Mechanical failure of a lightweight polypropylene mesh.  

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We report the case of a 41-year-old male who underwent repair of a recurrent midline abdominal incisional hernia with components separation. The hernia defect was repaired with a 30 cm × 30 cm underlay biological (Strattice) mesh used to partially bridge a small residual gap between the rectus muscles and reinforced with a 30 cm × 30 cm lightweight polypropylene onlay mesh (BARD™ soft mesh). The patient later developed a large persistent seroma that was excised 18 weeks later. On exploration of the previous hernia repair, it was noted that the onlay polypropylene mesh had fractured leaving a 3 cm by 2 cm defect, but the underlying biological mesh was intact preventing a recurrence of the hernia (see Fig. 1). The fractured mesh was repaired with an additional onlay 10 cm × 10 cm polypropylene mesh, the seroma was de-roofed, and the patient was later discharged. This case highlights the early mechanical failure of a lightweight polypropylene mesh; the precise mechanism of failure in this case is unclear and, however, may be related to high intra-abdominal pressures postoperatively. Fig. 1 Photograph showing onlay polypropylene (BARD™ soft mesh) mesh superficial to a biological (Strattice) sublay mesh bridging the recti (on the left and right wound edges). Arrow indicates the 2 cm by 3 cm fracture. PMID:22824989

Lintin, L A D; Kingsnorth, A N

2014-02-01

90

Effect of ?-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials  

International Nuclear Information System (INIS)

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of ?-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity

91

Effect of ?-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials  

Science.gov (United States)

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of ?-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity.

George, Johnsy; Kumar, R.; Sajeevkumar, V. A.; Sabapathy, S. N.; Vaijapurkar, S. G.; Kumar, D.; Kchawahha, A.; Bawa, A. S.

2007-07-01

92

Stahl's ear correction: synergistic use of cartilage abrading, strategic Mustarde suture placement, and anterior anticonvexity suture.  

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Stahl ear deformity is characterized by a third auricular crus with a horizontal orientation. A diminutive superior crus and prominence of the upper pole of the ear are also generally present. Many acknowledge that Stahl ear is a challenging deformity to correct. In the present report, an effective technique is introduced that uses 3 different, yet synergistic, maneuvers to oblate the third crus, enhance the superior crus, and normalize superior pole projection. The maneuvers are posterior abrading of the third crus, strategic placement of a posterior Mustarde suture, and placement of an anterior anticonvexity suture. Postoperative care involves the use of a custom scaphoid fossa splint and headband. PMID:22565922

Weinfeld, Adam Bryce

2012-05-01

93

[Comparison between antibacterial coated suture vs standard suture to prevent the surgical site infections].  

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The surgical site infections (SSI) still represent an issue, which causes prolonged hospital staying, major costs for both healthcare system and professional insurance. Recent studies enlighten that using the antibacterial agent triclosan® leads to decrease infections rates. In this observational study we compared two groups of patients undergoing scheduled the so called clean surgery. The absence of SSI was assessed in all patients, 30 days later the surgery, through a telephone interview as indicated by the National Group for SSI surveillance protocol. The use of antibacterial sutures shows to be successful in preventing the SSI in comparison to standard sutures, even if results are not statistically significant. PMID:23591032

Palma, Elisabetta; Brocanelli, Nicoletta; Luconi, Antonella; Cicolini, Giancarlo

2013-01-01

94

The effect of ?-irradiation on polypropylene  

International Nuclear Information System (INIS)

Change of mechanical strength, thermal properties, and IR spectroscopy were studied for the ? ray irradiation of isotactic polypropyiene under various conditions, such as vacuum or air or at room temperature. The change of crystalinity was calculated from the IR spectroscopy and the change of melting point was measured too. And the effects of storage time were compared. For irradiation under vacuum, the G value of crosslinking and scission were calculated by measuring gel fractiion. There was a significant decrease in the tensile break stress and strain of irradiated polypropylene in air for all doses but slight decrease in stress and strain of irradiated polypropylene in vacuum

95

Organobentonite / Polypropylene Nanocomposite for Packaging Application  

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Na-bentonite was treated with several kind of quaternary alkyl ammonium cation by ion exchange reaction to find the high efficiency one to exfoliate the longer of nanoclay. DOEM exhibited the good performance to continue the work. The organomodified bentonite was compounded with polypropylene by using Surlyn^ ionomer as a compatibilizer to produce the packaging film. In addition the organobentonite was modified by ethylene scavenger chemical and characterized by XRD and FT-IR. It was compound with polypropylene to prepare the active packaging film.The gas permeability, ethylene adsorption-desorption, thermal and mechanical properties were investigated.

Varothai, Yukhanthorn; Phandee, Atinuch; Nithitanakul, Manit; Magaraphan, Rathanawan; Manuspiya, Hathaikarn

2007-03-01

96

Polypropylene mesh repair of incisional hernia  

International Nuclear Information System (INIS)

Objective: The purpose of this study is to report the results of tension-free repair of primary and recurrent incisional hernias using polypropylene (Prolene) mesh. Results: The mean age was 43.7 years. The only death occurred in a known cirrhotic presenting with obstructed hernia. Another patient was seen developing seroma and wound infection in one case. No recurrence was seen during the mean follow-up period of 2.2 years. Conclusion: the tension-free repair of incisional hernia, with polypropylene mesh in extra facial position, is safe and easy procedure with acceptable morbidity and no recurrence. (author)

97

Degradation study of polypropylene (PP) and bioriented polypropylene (BOPP) in the environment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polymers are vastly employed for numerous purposes in different industrial segments and generate soaring quantities of discarding in the environment. This research analyzed the degradability/biodegradability of polypropylene films (PP) and Bioriented polypropylene (BOPP) polymers after 11 months interred in the São Giácomo landfill in Caxias do Sul. Comparing the buried PP film to a sample of virgin PP, two peaks of degrading activity appeared at the TG curve as well as structure modificati...

Carina Longo; Michele Savaris; Mára Zeni; Rosmary Nichele Brandalise; Ana Maria Coulon Grisa

2011-01-01

98

Blueschists in major suture zones of China  

Science.gov (United States)

Blueschist facies rocks and C-type eclogites occur as allochthonous terranes or as small tectonic blocks in almost all the accretionary fold belts and major suture zones within the interior of China and along the Circum-Pacific and Tethys-Himalayan belts. At least forty blueschist localities have been described. Blueschists around the Pacific margins and the Himalaya-Alpine belts are mostly Mesozoic in age; only those in Taiwan and New Caledonia are Cenozoic. Intracratonal blueschists of China are older than Late Permian, when the collision-amalgamation presumably occurred. Several alleged Precambrian blueschist localities [Ye, 1987] are shown in the recently published Metamorphic Map of China. A Precambrian(?) blueschist belt in Anhui-Hubei (central China) extends for about 2300 km. However, except for the pre-Sinian blueschist terrane in Aksu, the age determination for Precambrian blueschist metamorphism elsewhere has not been confirmed. Characteristic features of Chinese blueschists include the following: (1) blueschist facies metamorphism predates the continental collision-amalgamation, (2) most blueschists have undergone multistage metamorphism, commonly with increasing temperature and/or decreasing pressure for later events, (3) assemblages include sodic amphibole + epidote + albite + quartz + phengite + chlorite + sphene; lawsonite, jadeitic pyroxene, and aragonite are not common, and (4) protoliths are mainly mafic, pelagic, and clastic rocks. Blueschist facies metamorphism in China may be divided into two types on the basis of the imposed geothermal gradient, hence the progressive change in mineral assemblage. The rare lawsonite-bearing blueschists produced at lower temperatures and higher pressures are confined to the Inner Mongolia and Yarlung Zangbo suture zones where aragonite and possibly jadeitic pyroxene + quartz occur, and the blueschists are associated with subgreenschist facies rocks. Most other blueschists of China formed at higher temperatures along the transitional blueschist-greenschist facies boundary where epidote, sodic, and calcic amphiboles are ubiquitous, and the blueschists are interlayered with greenschist facies rocks. The common occurrence of intracratonal blueschists in major suture zones of China and elsewhere in Eurasia indicates pre-Mesozoic subduction-accretion of oceanic crust and flysch sediments. These zones of accretion represent growth around the periphery of major Precambrian cratons. This fact, together with the distribution of ophiolite belts and available paleomagnetic data, provides evidence for an extremely mobile history of plate movement in Eurasia. However, the Paleozoic intracontinental blueschists and ophiolites of China have formed before, rather than during, final closure between cratons. They do not usually mark the location of terminal sutures but are the result of earlier accretion and continental growth by subduction, underplating, and imbrication of oceanic materials similar to the accretion history of westernmost North America.

Liou, J. G.; Wang, Xiaomin; Coleman, R. G.; Zhang, Zh. M.; Maruyama, S.

1989-06-01

99

Chorioretinitis caused by synthetic absorbable sutures.  

Science.gov (United States)

Two cases of chorioretinitis were caused by polymer material from the suture (Dexon) used in squint surgery. The lesions were macula edema, granulomatous uveitis and capillary occlusions on the ocular fundus located in the operated area. To confirm the cause of this injury, an immunological investigation was performed. Macrophage block and an incomplete adjuvant were necessary to lead delayed hypersensitivity against the synthetic polymer polyglycolic acid (PGA). The mice showed a strong reaction as hyperemia and swelling on their experimental footpads after the injection of PGA. Histologically the footpad accumulated a large quantity of lymphocytes in the swollen tissue but the control footpad had no reaction. PMID:1338756

Yamanaka, T

1992-01-01

100

Registration temperature effect in polypropylene detectors  

Energy Technology Data Exchange (ETDEWEB)

The registration temperature effect (RTE) was investigated using two types of polypropylene (PP) detectors. It was found that the RTE depends on the content of radical scavenger in the polymer. The results are compared with published radiothermoluminescence data and discussed in terms of relaxation transitions. (Author).

Apel, P.Y.; Didyk, A.Y.; Kravets, L.I.; Kuznetsov, V.I. [Joint Inst. for Nuclear Research, Dubna (Russian Federation); Fursov, B.I. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

1993-12-31

 
 
 
 
101

Does UV disinfection compromise sutures? An evaluation of tissue response and suture retention in salmon surgically implanted with transmitters  

Energy Technology Data Exchange (ETDEWEB)

Ultraviolet radiation (UVR) can be used as a tool to disinfect surgery tools used for implanting transmitters into fish. However, the use of UVR could possibly degrade monofilament suture material used to close surgical incisions. This research examined the effect of UVR on monofilament sutures to determine if they were compromised and negatively influenced tag and suture retention, incision openness, or tissue reaction. Eighty juvenile Chinook salmon Oncorhynchus tshawytscha were surgically implanted with an acoustic transmitter and a passive integrated transponder. The incision was closed with a single stitch of either a suture exposed to 20 doses of UV radiation (5 minute duration per dose) or a new, sterile suture. Fish were then held for 28 d and examined under a microscope at day 7, 14, 21 and 28 for incision openness, ulceration, redness, and the presence of water mold. There was no significant difference between treatments for incision openness, redness, ulceration or the presence of water mold on any examination day. On day 28 post-surgery, there were no lost sutures; however, 2 fish lost their transmitters (one from each treatment). The results of this study do not show any differences in negative influences such as tissue response, suture retention or tag retention between a new sterile suture and a suture disinfected with UVR.

Walker, Ricardo W.; Brown, Richard S.; Deters, Katherine A.; Eppard, M. B.; Cooke, Steven J.

2013-10-01

102

Prospective randomized controlled trial investigating the type of sutures used during hepatectomy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

AIM: To determine whether absorbable sutures or non-absorbable sutures are better in preventing surgical site infection (SSI), in this paper we discuss the results of a randomized clinical trial which examined the type of sutures used during hepatectomy.

2011-01-01

103

21 CFR 878.4494 - Absorbable poly(hydroxybutyrate) surgical suture produced by recombinant DNA technology.  

Science.gov (United States)

...surgical suture produced by recombinant DNA technology. 878.4494 Section...surgical suture produced by recombinant DNA technology. (a) Identification...Surgical Suture Produced by Recombinant DNA Technology.” For the...

2010-04-01

104

Nose tip refinement using interdomal suture in caucasian nose  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Refinement of the nose tip can be accomplished by a variety of techniques, but currently, the use of sutures in the nasal tip with conservative resection of the alar cartilage is the most frequently recommended approach. Objective: To classify the nasal tip and to demonstrate the interdomal suture applied to nasal tip refinement in the Caucasian nose, as well as to provide a simple and practical presentation of the surgical steps. Method: Development of surgical algorithm for nasal tip surgery: 1. Interdomal suture (double binding suture, 2. Interdomal suture with alar cartilage weakening (cross-hatching, 3. Interdomal suture with cephalic removal of the alar cartilage (McIndoe technique based on the nasal tip type classification. This classification assesses the interdomal distance (angle of domal divergence and intercrural distance, domal arch width, cartilage consistency, and skin type. Interdomal suture is performed through endonasal rhinoplasty by basic technique without delivery (Converse-Diamond technique under local anesthesia Conclusion: This classification is simple and facilitates the approach of surgical treatment of the nasal tip through interdomal suture, systematizing and standardizing surgical maneuvers for better refinement of the Caucasian nose.

Pasinato, Rogério

2012-01-01

105

Structural grafts and suture techniques in functional and aesthetic rhinoplasty  

Directory of Open Access Journals (Sweden)

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.

Gassner, Holger G.

2010-01-01

106

A biomechanical comparison of suture constructs used for coracoclavicular fixation.  

Science.gov (United States)

There is no consensus regarding surgical treatment for severely dislocated acromioclavicular joints. Although many treatments are suture-based, the suture materials and resulting suture-bone constructs have been subjected to limited systematic evaluation. This study identifies the strongest and least deforming suture construct among those commonly used for such repairs. Each suture-based repair was tested on a simulated clavicle and coracoid process with the skeletal components distracted until the suture failed to obtain tensile strength. Additional groups of sutures were subjected to cyclic loading to determine resistance to deformation. Panacryl braid had significantly greater tensile strength than all other constructs: Polydioxanone (PDS) braid, Mersilene tape, and Ethibond #5. Deformation after cyclic loading of Panacryl braid, PDS braid, and two strands of Mersilene tape was significantly less than that of the other constructs. A bioabsorbable suture loop, such as Panacryl, can act as a temporary internal splint, maintaining acromioclavicular joint reduction long enough for ligamentous healing during rehabilitation, and can avoid complications associated with permanent fixation materials. Panacryl braid deserves serious consideration for coracoclavicular fixation because of its strength, resistance to deformation, and bioabsorbable properties. PMID:14577722

Wickham, M Quinn; Wyland, Douglas J; Glisson, Richard R; Speer, Kevin P

2003-01-01

107

Arthroscopic transosseous suture anchor technique for rotator cuff repairs.  

Science.gov (United States)

The skin is incised 1 to 2 cm distal to the lateral portal. A transosseous tunnel is created through the greater tuberosity by a sharp penetrator, entering 1.5 to 2 cm distal to the top of the greater tuberosity. The penetrator exits medially, between the tip of the greater tuberosity and the articular surface of the humeral head, in the middle of the footprint. The first anchor, a 5-mm Spiralok (DePuy Mitek, Norwood, MA) is placed at the penetrator's exit site on the footprint. Using a specially designed suture leader, the lateral limb of the suture in the anchor, which passes through the previously created transosseous tunnel, is taken from the anchor and pulled out. The other suture end is passed through the supraspinatus tendon. The second suture, placed superficially in the anchor, is passed from the anchor through the supraspinatus tendon, as a mattress suture. If more anchors are required, the procedure should be repeated. The transosseous suture limb and the suture limb that is passed through the supraspinatus tendon are tied through the lateral portal. The knot tying is then performed with a sliding Delimar knot. The mattress suture, passing through the supraspinatus tendon, is tied through the anterior lateral portal. The knot tying procedure is repeated depending on the number of anchors. PMID:16651169

Cicak, Nikola; Klobucar, Hrvoje; Bicanic, Goran; Trsek, Denis

2006-05-01

108

Effect of Braiding and Hot Stretching Conditions on Sutures Performances  

Directory of Open Access Journals (Sweden)

Full Text Available The success of wound healing depends on suture performances, such as slippage ratio, deformation recovery, knot performance and tensile properties. The main objective of this study is to determine the effect of manufacturing parameters related to braiding and hot stretching steps on suture performances. Obtained results showed that hot stretching contributes to macromolecular chains arrangement as well as suture performances and structural properties improving. The percentage of crystallinity of fabricated suture was ameliorated by hot stretching suture and reaches 25.51% under temperature of 170C and during 3 min. An increase of hot stretching load to 15 N reduces slippage ratio and improves percentage of deformation recovery as a consequence of the improving of macromolecular chains arrangement.

Faten Debbabi

2011-01-01

109

Albumin-coated bioactive suture for cell transplantation.  

Science.gov (United States)

Cell therapy holds the promise for a novel modality in the surgical toolkit; however, delivery of cells into damaged soft tissues constitutes a challenge. The authors hypothesized that growing stem cells on the surface of absorbable sutures in vitro and then implanting them via stitching would be a suitable delivery route for cell therapy. Fibronectin, poly-L-lysine, and albumin coatings were used to increase attachment of human and rat bone-marrow-derived mesenchymal stem cells (BMSC) to polyfilament absorbable sutures in vitro. Fluorescence microscopy was performed to localize the cells on the suture. After 48 hours of incubation, the albumin-coated sutures had the highest cell number, and after 168 hours cell number reached confluency. In the in vivo experiments, a 10-mm incision was made on the triceps surae muscle of male Wistar rats and rat BMSC coated sutures were placed into the muscle. Two days after the implantation, cells were seen on the surface of the sutures as well as in the surrounding muscle tissue. Long-term results at 5 weeks showed that transplanted cells survived and the sutures were partly absorbed. In conclusion, coating absorbable sutures with proteins, especially serum albumin, improves attachment and proliferation of cells, and only 48 hours in culture is enough to cover the sutures sufficiently. Using these stitches in vivo resulted in short-term and long-term survival of cells. As a result, albumin-coated suture can be a vehicle for stem cell therapy in soft tissues such as muscle, tendon, or peripheral nerves. PMID:22717700

Horváthy, Dénes Balázs; Vácz, Gabriella; Cselenyák, Attila; Weszl, Miklós; Kiss, Levente; Lacza, Zsombor

2013-06-01

110

The effect of two nonresorbable suture types on the mechanical performance over a metal suture anchor eyelet.  

Science.gov (United States)

An understanding of the mechanical properties of different suture materials is valuable when selecting the most appropriate suture and repair technique. Sutures should be strong, easy to handle and have high knot security. The introduction of suture anchors adds an additional variable regarding the effect of stress risers over the eyelet. Improving the mechanical properties of a suture may be a possible method to help avoid failure over stress risers such as the eyelet of suture anchor. This study examined the static and viscoelastic properties of a new polyethylene based non-resorbable suture (Fibrewire) over the eyelet of a standard anchor compared to braid polyester non-resorbable suture (Ethibond). Fibrewire had superior ultimate load properties compared to Ethibond (360.2 N+/-23.8 vs 191.9 N+/-17.3) as well as greater stiffness (61.3 N/mm+/-9.7 vs 8.1 N/mm+/-0.4) when tested in uniaxial tension through a metal anchor eyelet (Mitek) ( psuture may have implications in the post-operative period or during rehabilitation. PMID:13680105

Acton, D; Perry, A; Evans, R; Butler, A; Stephens, P; Bruce, W; Goldberg, J; Sonnabend, D; Walsh, W R

2004-03-01

111

Usefulness of continuous suture using short-thread double-armed micro-suture for cerebral vascular anastomosis  

Science.gov (United States)

Background: When microvascular anastomosis is performed in a deep, narrow operating field, securing space to throw knots is difficult. To simplify the procedure and avoid obstruction of the anastomosis, we use a continuous suturing with short-thread double-armed micro-suture. Methods: Sixty-four patients (38 cerebral revasculazation, 16 moyamoya disease, and 10 aneurysm surgery) undergoing microvaucular anastomosis were included. During anastomosis, a continuous suture was placed with short-thread double-armed micro-suture. Results: During 64 microanastomosis procedures, 64 consecutive continuous sutures were performed with 1-year follow up. All patients showed patency of anastomosis with long-term follow up. Conclusions: This technique is especially useful for anastomosis in a deep, narrow surgical field, such as in superior cerebellar artery anastomosis.

Haga, Sei; Nagata, Shinji

2014-01-01

112

A Knotless Suture Anchor: Technique for use in arthroscopic Bankart repair.  

Science.gov (United States)

Arthroscopic Bankart repair performed using suture anchors most closely mimics open repair techniques. One of the challenges with the arthroscopic technique is tying consistent, good-quality arthroscopic knots. The unique Knotless Suture Anchor (Mitek Products, Westwood, MA) and method of use for arthroscopic Bankart repair is described. The Knotless Suture Anchor has a short loop of suture secured to the tail end of the anchor. A channel is located at the tip of the anchor that functions to capture the loop of suture after it has been passed through the ligament. The ligament is tensioned as the anchor is inserted into bone to the appropriate depth. The doubled suture configuration that is created with the loop increases the suture strength in the Knotless Suture Anchor compared with standard suture anchors with the same size suture. To my knowledge, this article describes the first knotless suture anchor. A secure, low-profile repair can be created without arthroscopic knot tying. PMID:11172255

Thal, R

2001-02-01

113

Cyclic viscoelastoplasticity of polypropylene/nanoclay composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Observations are reported on isotactic polypropylene/organically modified nanoclay hybrids with concentrations of filler ranging from 0 to 5 wt.% in cyclic tensile tests with a stress–controlled program (oscillations between various maximum stresses and the zero minimum stress). A pronounced effect of nanofiller is demonstrated: reinforcement with 2 wt.% of clay results in strong reduction of maximum and minimum strains per cycle and growth of number of cycles to failure compared with neat ...

Drozdov, A.; Christiansen, Jesper Claville

2012-01-01

114

POLYPROPYLENE/CLAY NANOCOMPOSITES: SYNTHESIS AND CHARACTERIZATION  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polypropylene nanocomposites were synthesized by using the method of mixing in the molten state. Nanocomposites were obtained in twin-screw co-rotating extruders and the nanocomposites were prepared with percentage of nanoclay (C2) from 5 wt-%, with and without compatibilizer agent (PP-g-MA). The thermal (DSC, TGA), morphology (XRD, TEM), and dynamical mechanical (DMA) properties of the nanocomposites were characterized. All nanocomposites prepared are in intercalated state as corroborated by...

Pe?rez, Mo?nica A.; Rivas, Bernabe? L.; Rodri?guez, Saddys M.; ÁLVARO MALDONADO; CAROLA VENEGAS

2010-01-01

115

Compression of polypropylene across a wide range of strain rates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Three grades of polypropylene were tested in uniaxial compression at room temperature, across a wide range of strain rate: 10-4 s-1 to 104 s-1. One grade is a conventional polypropylene homopolymer. The two other grades are the polypropylene forming the matrix phase of a continuous glass fibre-reinforced thermoplastic composite prepreg, with and without blending with a carbon-black master batch. Tests at the highest strain rates were performed using a compression split Hopkinson pressure bar....

Okereke, Mi; Buckley, Cp; Siviour, Cr

2012-01-01

116

EVALUATION OF COMPOSITE POLYPROPYLENE FIBRE REINFORCED CONCRETE  

Directory of Open Access Journals (Sweden)

Full Text Available Improvements in fly ash based concrete strength in compression and flexural direction are the main objectives of this study. The compressive and flexure strength of concrete for various mixtureproportions of concrete containing the inclusions of different percentage of polypropylene fibers from 0% to 0.3% and fly ash replacement levels at 25% , 50% of fly ash were investigated. The experimental test results showed that PP fibers possess increased extensibility and tensile strength, both at first crack and at ultimate, particular under flexural loading; and the fibers were able to hold the matrix together even after extensive cracking. The net result of all these is to impart to the fiber composite pronounced post – cracking ductility which is absence of ordinary concrete. To provide a basis for comparison, reference concrete specimens were cast without polypropylene fiber. The experimental test result showed that the addition of polypropylene fibers at 0.1% volume fraction (Vf showed a consistent improvement in the concrete strength of 44.50 MPa and 55.50 MPa at 7 and 28 days respectively.

V.M. Sounthararajan

2013-04-01

117

Cyclic viscoelastoplasticity of polypropylene/nanoclay composites  

DEFF Research Database (Denmark)

Observations are reported on isotactic polypropylene/organically modified nanoclay hybrids with concentrations of filler ranging from 0 to 5 wt.% in cyclic tensile tests with a stress–controlled program (oscillations between various maximum stresses and the zero minimum stress). A pronounced effect of nanofiller is demonstrated: reinforcement with 2 wt.% of clay results in strong reduction of maximum and minimum strains per cycle and growth of number of cycles to failure compared with neat polypropylene. To rationalize these findings, a constitutive model is developed in cyclic viscoelasticity and viscoplasticity of polymer nanocomposites. Adjustable parameters in the stress–strain relations are found by fitting experimental data. The model correctly describes the growth of the ratcheting strain and shows that fatigue failure is driven by a pronounced increase in plastic strain in the crystalline phase. To assess the influence of loading conditions on the changes in the material parameters, experimental data on polypropylene are studied in cyclic tests with a strain–controlled program (oscillations between fixed maximum and minimum strains) and a mixed program (oscillations between various maximum strains and the zero minimum stress). Numerical simulation confirms the ability of the model to predict the evolution of stress–strain diagrams with the number of cycles.

Drozdov, A.; Christiansen, Jesper de Claville

2012-01-01

118

High strain rate behaviour of polypropylene microfoams  

Science.gov (United States)

Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

2012-08-01

119

Cyclic viscoelastoplasticity of polypropylene/nanoclay composites  

Science.gov (United States)

Observations are reported on isotactic polypropylene/organically modified nanoclay hybrids with concentrations of filler ranging from 0 to 5 wt.% in cyclic tensile tests with a stress-controlled program (oscillations between various maximum stresses and the zero minimum stress). A pronounced effect of nanofiller is demonstrated: reinforcement with 2 wt.% of clay results in strong reduction of maximum and minimum strains per cycle and growth of number of cycles to failure compared with neat polypropylene. To rationalize these findings, a constitutive model is developed in cyclic viscoelasticity and viscoplasticity of polymer nanocomposites. Adjustable parameters in the stress-strain relations are found by fitting experimental data. The model correctly describes the growth of the ratcheting strain and shows that fatigue failure is driven by a pronounced increase in plastic strain in the crystalline phase. To assess the influence of loading conditions on the changes in the material parameters, experimental data on polypropylene are studied in cyclic tests with a strain-controlled program (oscillations between fixed maximum and minimum strains) and a mixed program (oscillations between various maximum strains and the zero minimum stress). Numerical simulation confirms the ability of the model to predict the evolution of stress-strain diagrams with the number of cycles.

Drozdov, A. D.; deC. Christiansen, J.

2012-11-01

120

Effects of ?-ray irradiation on polypropylene  

International Nuclear Information System (INIS)

The authors have found that the G-value of free radical formation by ?-ray irradiation on polyolefin depends on the higher order structure. Therefore, efforts were made to separately observe the changes in the amorphous and crystalline phases by ?-irradiation using visco-elastic measurement, differential scanning calorimetry, and X-ray method. Isotactic polypropylene was chosen as the material. The drawn and bulk samples were irradiated by ?-ray of 60Co at room temperature. Wide angle X-ray diffraction was measured to estimate the lattice constant and the halfwidth of the diffraction peak. The results obtained were discussed for the change of dynamic loss modulus E'' with temperature for the bulk samples, irradiation effects on the viscoelastic behavior of the drawn samples, and thermograms for the undrawn and drawn samples. Polypropylene has been classified as a cross-linking type polymer. In the amorphous phase, cross-linking occurs to increase the temperature location of ?a absorption. While it was found that crystal imperfection was introduced by irradiation from the illustrated facts. This crystal imperfection can be introduced by two mechanisms, (1) cross-linking formation between adjacent chains, and (2) chain scission to form chain ends. The mechanism (2) seems to be responsible for the crystal imperfection resulting in decrease of maximum temperature in polypropylene. (Wakatsuki, Y.)

 
 
 
 
121

Development of braided drug-loaded nanofiber sutures  

International Nuclear Information System (INIS)

The objectives of this work are twofold. Firstly, while most work on electrospinning is limited to the development of only functional materials, a structural application of electrospun nanofibers is explored. Secondly, a drug-loaded tissue suture is fabricated and its various properties are characterized. Braided drug-loaded nanofiber sutures are obtained by combining an electrospinning process with a braiding technique followed by a coating procedure. Two different electrospinning techniques, i.e. blend and coaxial electrospinning, to incorporate a model drug cefotaxime sodium (CFX-Na) into poly(L-lactic acid) (PLLA) nanofibers have been applied and compared with each other. Properties of the braided drug-loaded sutures are characterized through a variety of methods including SEM, TEM and tensile testing. The results show that the nanofibers had a preferable micromorphology. The drug was incorporated into the polymer nanofibers homogeneously, with no cross-linking. The nanofibers maintained their fibrous structures. An in vitro release study indicates that the drug-loaded nanofibers fabricated by blend electrospinning and coaxial electrospinning had a different drug release behavior. An inhibition zone experiment shows that both sutures obtained from the nanofibers of the different electrospinning techniques had favorable antibacterial properties. The drug-loaded sutures had preferable histological compatibility performance compared with commercial silk sutures in anompared with commercial silk sutures in an in vivo comparative study.

122

[Suture technics for the abdominal wall after midline laparotomy].  

Science.gov (United States)

During the last 10 years 268 laparotomies by a midline incision were performed. A high incidence of seromas, fistulas caused by suturing material and wound ruptures were observed. After finding only a small number of publications in the veterinary medicine about wound healing disturbances an analysis of the human medical literature was done. This induced the change of our surgical procedure and suturing technique: The midline incision and surgical management during the laparotomies in 14 horses suffering from colic were performed by a minimized trauma. The abdominal wall was closed layer by layer in the following manner: peritoneum by a running suture of catgut metric 5, linea alba by Sultan single sutures of polyglycolic acid material metric 5 (12 cases) or of polydioxanone metric 4 (2 cases), subcutaneous layer by a running suture of polyglycolic acid material metric 4, skin by single sutures of monofilamentous synthetic material metric 2. Thus, no complications in wound healing were observed in these 14 horses. Therefore, we recommend to prove the described surgical and suturing procedure by a larger number of horses undergoing a laparotomy by a midline incision. PMID:3907012

Becker, M

1985-01-01

123

Granuloma formation secondary to Achilles tendon repair with nonabsorbable suture  

Science.gov (United States)

INTRODUCTION Several complications can be observed after Achilles tendon repairs. In this study we aimed to report granuloma formation secondary to Achilles tendon repair with Ethibond (Ethicon INC, Somerville, New Jersey) suture. PRESENTATION OF CASE A 31 year-old man operated for Achilles tendon rupture. The Ethibond suture was used for primary repair. The patient attended to polyclinic with the complaints of swelling and discharge around the operation site four months after operation. A mass around distal portion of the Achilles tendon was detected. The granulomatous tissue was excised. Inside the mass Ethibond suture was detected. On histopathologic examination, typical findings of the foreign body reaction were observed. No microorganism was cultivated in the tissue culture. The patient has no complaint on the twelfth month control after surgery. DISCUSSION The results of primary repair of Achilles tendon are good but several complications were reported. In tendon repairs generally nonabsorbable sutures are used. The Ethibond is nonabsorbable, braided suture. In the literature, granuloma formations secondary to the suture materials such as polygylactine and braided polyethylen–polyester after Achilles tendon repair were reported but granuloma secondary to the Ethibond is very rare. CONCLUSION Although Ethibond suture is a strong and safe material for Achilles tendon repairs it may cause soft tissue problems such as granuloma. PMID:25212905

Kara, Adnan; Celik, Haluk; Seker, Ali; Uysal, Mehmet Ali; Uzun, Metin; Malkoc, Melih

2014-01-01

124

Green aqueous surface modification of polypropylene for novel polymer nanocomposites.  

Science.gov (United States)

Polypropylene is one of the most widely used commercial commodity polymers; among many other applications, it is used for electronic and structural applications. Despite its commercial importance, the hydrophobic nature of polypropylene limits its successful application in some fields, in particular for the preparation of polymer nanocomposites. Here, a facile, plasma-assisted, biomimetic, environmentally friendly method was developed to enhance the interfacial interactions in polymer nanocomposites by modifying the surface of polypropylene. Plasma treated polypropylene was surface-modified with polydopamine (PDA) in an aqueous medium without employing other chemicals. The surface modification strategy used here was based on the easy self-polymerization and strong adhesion characteristics of dopamine (DA) under ambient laboratory conditions. The changes in surface characteristics of polypropylene were investigated using FTIR, TGA, and Raman spectroscopy. Subsequently, the surface modified polypropylene was used as the matrix to prepare SiO2-reinforced polymer nanocomposites. These nanocomposites demonstrated superior properties compared to nanocomposites prepared using pristine polypropylene. This simple, environmentally friendly, green method of modifying polypropylene indicated that polydopamine-functionalized polypropylene is a promising material for various high-performance applications. PMID:24841134

Thakur, Vijay Kumar; Vennerberg, Danny; Kessler, Michael R

2014-06-25

125

Ophiolite belts in the sw-iberian variscan suture  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The SW-Iberia Variscan suture is the boundary between the Iberian (IT) and the South-Portuguese (SPT) Terranes, materializing the closure of Rheic and related oceans by northeast ward subduction of the SPT under the IT. The western segment of this suture displays imbrications of various units belonging to: (1) Neoproterozoic - Lower Palaeozoic Ossa Morena Zone (OMZ) relative autochthonous (locally covered by Lower-Middle Devonian limestones and shales); and (2) allochthonous complexes. The la...

Ribeiro, Anto?nio; Pedro, Jorge; Tassinari, Colombo; Munha?, Jose?; Arau?jo, Alexandre; Fonseca, Paulo; Mateus, Anto?nio; Gil, Pedro

2008-01-01

126

Sutures and iris wound-healing in the baboon.  

Science.gov (United States)

This paper reports an experimental study of iris wound-healing and the response of iris tissue in baboons to different suture materials following a planned surgical incision. The wound was sutured with 8-0 virgin silk, 22 mum Ethilon or 7-0 chromacised catgut, or left unsutured. The iris produces a minimal inflammatory response to aseptic trauma characterised by round cell infiltration, clump cell proliferation, pigment cell proliferation from the posterior epithelial surface and proliferation of non-pigmented ciliary epithelium (knots). This response is associated with microscopic hemorrhages in the iris. There does not appear to be any fibrous union of wound edges, instead the wound surfaces become lined with a layer of pigmented cells, probably from the posterior epithelium. Sutures play the dual role of accurately apposing the wound edges and, because there is no fibrous union of iris tissue, of keeping them in apposition. Therefore, they must remain in situ permanently. Catgut is poorly tolerated by the iris and is eventually absorbed. For these two reasons it is unsuitable. Ethilon is the least reactive and virgin silk only slightly more reactive. Both of these are suitable for iris suture. The suture material at present available is not entirely satisfactory. Finer suture material is required to reduce even more the iris response to sutures. Needles, even those supplied with Ethilon or virgin silk, are too large and clumsy. The answer to this problem probably lies in strengthening and sharpening the suture material ends so that they can act as needles. PMID:1098426

Luntz, M H; Kaufmann, J C; Spiller, M

1975-01-01

127

Single suture laparoscopic tubal re-anastomosis.  

Science.gov (United States)

The goal of this article is to report our experience and review recent articles obtained for laparoscopic tubal sterilization reversal. The technique we describe is 'single suture laparoscopic tubal re-anastomosis'. This technique is simple and atraumatic and requires only one stitch in the tube. After preparing the tube stumps and bringing the edges of the mesosalpinx together, laparoscopic anastomosis is achieved by one stitch placed at '12 o'clock' on the antimesial edge of the tube. Between May 1994 and June 1997 we operated on 32 patients using this technique and carried out 48 tubal sterilization reversals. For the patients who underwent postoperative hysterosalpingography during the first or second month after the operation, the rate of patency was 87.5% (42/48). The overall intrauterine pregnancy rate was 53.1% (17 out of 32 patients). The overall delivery rate was 40.6% (13 out of 32 patients). The intrauterine pregnancy rate for the 17 patients who were aged 38 years or under was 58.8% (10 out of 17 patients). Laparoscopic tubal sterilization reversal is feasible with a simplified technique. Review of the publications concerning laparoscopic microsurgical tubal anastomosis confirms satisfactory fertility results. The surgeon should be experienced in microsurgical tubal anastomosis by laparotomy as well as operative laparoscopic procedures. PMID:9719882

Dubuisson, J B; Chapron, C

1998-08-01

128

The sutured Floer polytope and taut depth one foliations  

CERN Document Server

For closed 3-manifolds Ozsv\\'ath and Szab\\'o, Ni, and Hedden show that there exists a certain duality between an appropriate flavour of the Heegaard Floer polytope and the Thurston norm unit ball. For instance, extremal vertices of the HF^+ polytope carrying the group Z correspond bijectively to the fibred faces of the Thurston norm unit ball. We prove a similar result for sutured manifolds and taut depth one foliations. Equivalence classes of taut depth one foliations of a sutured manifold form foliation cones, defined by Cantwell and Conlon. We show that the extremal vertices of the sutured Floer polytope carrying the group Z correspond bijectively to these foliation cones. Moreover, the foliation cones are subtended by the foliated faces of an asymmetric seminorm arising from the dual sutured Floer polytope. In some cases this seminorm has a purely geometric definition akin to that of the sutured Thurston norm. An important step in our work is the following fact: a sutured manifold admits a fibration or a ...

Altman, Irida

2012-01-01

129

Effects of two suture techniques in conjunctival autograft surgery  

Directory of Open Access Journals (Sweden)

Full Text Available AIM: To compare the effects of continuous side whipstitch suture and interrupted suture in conjunctival autograft surgery after resection of primary pterygium.METHODS: A comparative, prospective and randomized clinical trial was performed in 48 eyes of 48 patients with primary pterygium. All patients were randomly divided into two groups with 24 eyes of 24 patients in each group. In group A and B, continuous side whipstitch suture and interrupted suture were respectively adopted. The time spent in suture was recorded during surgery. The postoperative ocular discomfort and the time spent in taking out stitches were recorded during the 6-month follow-up. RESULTS: The average surgical time was 14.05±2.30 minutes for group A and 19.34±2.12 minutes for group B(Prd (1.32±0.60 vs 1.68±0.35, Pth(0.87±0.24 vs 1.26±0.68, PPCONCLUSION: In the surgical management of primary pterygium, continuous side whipstitch suture can improve the surgical efficiency and decrease the ocular discomfort in the postoperative period. It proves to be an excellent option for conjunctival autograft attachment in primary pterygium surgery.

Chao-Peng Li

2013-09-01

130

Bearing area: a new indication for suture anchor pullout strength?  

Science.gov (United States)

Studies performed to quantify the pullout strength of suture anchors have not adequately defined the basic device parameters that control monotonic pullout. The bearing area of a suture anchor can be used to understand and predict anchor pullout strength in a soft-bone model. First, conical-shaped test samples were varied in size and shape and tested for pullout in 5, 8, and 10 pcf sawbone models. Next, bearing area and pullout strength relationships developed from the test samples were validated against nine commercially available suture anchors, including the Mitek QuickAnchor and SpiraLok, Opus Magnum(2), ArthroCare ParaSorb, and Arthrex BioCorkscrew. The samples showed a direct correlation between bearing area and pullout strength. Increased insertion depth was a secondary condition that also increased pullout strength. The pullout strength for the suture anchors followed the predicted trends of conical devices based on their individual bearing areas. For the 5 and 8 pcf models, only two and three devices, respectively, fell outside the predicted pullout strength range by more than a standard deviation. The use of a synthetic sawbone model was validated against the pullout strength of an Arthrex Corkscrew in five fresh-frozen cadaver humeral heads. The bearing area of a suture anchor can be used to predict the pullout strength independent of design in a soft-bone model. This work helps provide a foundation to understand the principles that affect the pullout strength of suture anchors. PMID:19226593

Yakacki, Christopher Michael; Griffis, Jack; Poukalova, Mariya; Gall, Ken

2009-08-01

131

Evaluation of coated and uncoated synthetic absorbable sutures in rabbit limbal wounds.  

Science.gov (United States)

Polymer coatings have been applied to braided synthetic absorbable sutures to decrease tissue drag and improve knot tying characteristics. To examine the possibility that increased "slipperiness" would decrease knot security, coated (Dexon Plus) and uncoated (Dexon S) polyglycolic acid sutures were compared in rabbit limbal wounds. Both suture types had comparable knot security, tissue reaction, and absorption rates, while the coated sutures caused less tissue drag. Clinical trials of coated polyglycolic acid suture for limbal wounds are warranted. PMID:6298682

Sugar, A; Bahn, C F

1982-12-01

132

[Pathophysiologic aspects, progressive and new developments in absorbable fully synthetic suture materials].  

Science.gov (United States)

Polyglycolic acid (PGA) sutures and Polyglactin-910 sutures show only minimal tissue reaction, nearly no scar formation and no immunological reactions. PGA sutures of the third generation have the same advantages, but surgical handling is to much improved that they may be technically employed in unfavourable locations, e.g. gastrointestinal tract and respiratory organs. PGA sutures of the third generation and the new monofil Polydioxanon suture need special knot techniques. PMID:6306952

Lünstedt, B; Thiede, A

1983-01-01

133

Structure development in melt processing isotactic polypropylene, polypropylene blends/compounds and dynamically vulcanized polyolefin TPEs  

Science.gov (United States)

The influence of various fillers, nucleating agents and ethylene propylene diene terpolymer (EPDM) additive on crystalline modification (alpha-, beta- and smectic forms) and crystalline orientation of polypropylene in die extrudates, melt spun filaments, thick rods, blow molded bottles and injection molded parts of isotactic polypropylene (PP), its blends/compounds and dynamically vulcanized polypropylene thermoplastic elastomers (TPEs) were experimentally studied under a range of cooling and processing conditions. The phenomena of crystallization, polymorphism and orientation in processing of both thin and thick samples (filaments, rods, bottles and injection molded parts) were simulated through transport laws incorporating polymer crystallization kinetics. Continuous cooling transformation (CCT) curves for the various material systems investigated were developed under quiescent and uniaxial stress conditions. We applied experimental data on polymorphism of thin sections to predict crystalline structure variation in thick parts. The predictions were consistent with experiments. For filaments, the polypropylene crystalline orientation-spinline stress relationship is generally similar for the neat PP, blends/compounds and TPEs. However, the blends and TPEs have much lower birefringence apparently due to a lack of orientation in the rubber phase. It was shown that the polypropylene contribution to the birefringence for the neat PP and its blends is the same at the same spinline stress. For bottles, the inflation pressures used have little effect on orientation of either polypropylene crystals or disc-shaped talc filler. The talc discs are highly oriented parallel to the bottle surface. For the bottles without talc, the orientation of polypropylene crystallographic axes are low. The polypropylene crystallographic b-axes in the talc filled bottles are more highly oriented. For injection molded parts, it was found that a low orientation layer exists between the part surface and an intermediate highly oriented layer in the parts of neat PP and its blends/compounds. The thickness of this layer increases as the injection pressure decreases. This layer was not formed in the TPE parts. This would seem to be associated with the TPEs exhibiting a yield stress in shear flow and not exhibiting fountain flow in mold filling. For all parts studied, the orientation characteristics of polypropylene crystallographic axes in the highly oriented layer are similar from sample to sample. The strong orientation of the c-axis parallel to the machine direction and the b-axis perpendicular to the machine direction are observed in the highly oriented layer. The talc discs in both the highly oriented layer and the intermediate position are highly oriented parallel to the part face due to melt flow. At intermediate position in the talc-filled parts, the polypropylene crystallographic (040) planes prefer to align themselves parallel to the part surface but are not so well oriented when the talc is absent.

Yu, Yishan

134

Utilização do laser de argônio na remoção de sutura corneana Use of argon laser in corneal suture removal  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Descrever a técnica da retirada de sutura em córnea clara, evitando-se o contato da parte externa do fio com o meio intra-ocular e avaliar se esse procedimento evitaria infecções. MÉTODOS: Foi realizado estudo retrospectivo de 1.233 casos de retirada de sutura de mononylon 10.0 em córnea clara, utilizando-se laser de argônio para cortar o fio, no qual se avaliou a incidência de infecções. RESULTADOS: Em 1.071 olhos, um tiro foi suficiente para cortar o ponto. Em 162 olhos, o tiro do laser atingiu a parte epitelial da sutura, sendo necessários disparos extras para cortar a parte intra-estromal e, assim, retirá-la sem que a parte externa do fio passasse pelo interior da córnea. Não ocorreram complicações após a retirada da sutura. CONCLUSÕES: A técnica utilizada mostrou-se eficaz na remoção das suturas e possivelmente apresenta risco menor de infecção, uma vez que a parte do fio sobrejacente ao epitélio não entra em contato com as camadas mais internas da córnea, nem com a câmara anterior, não tendo sido observado nenhum caso de infecção nesta pesquisa.PURPOSE: To describe the technique of clear-cornea suture removal, that avoids the contact of the external part of the thread with the intraocular medium, and to evaluate whether this procedure would prevent infections. METHODS: A retrospective study of 1.233 cases of clear-cornea mononylon 10.0 suture removal, by the use of an argon laser to cut the thread, was performed. Incidence of infection was then assessed. RESULTS: In 1.071 eyes, one shot was enough to cut the stitch. In 162 eyes, the laser shot hit the epithelial part of the suture, making new shots necessary to cut the intrastromal part, and thus to remove it assuring that the outer part of the stitch would not come in to contact with the interior of the cornea. There were no complications after suture removal. CONCLUSIONS: The technique has shown to be effective in suture removal. And, possibly, presents a lower risk for infection, since the external part of the thread does not come in to contact with the innermost parts of the cornea, or with the anterior chamber. No cases of infection have been observed during this research.

Edélcio Vieira

2004-12-01

135

Cierre de la pared abdominal: qué técnica y qué sutura se deben usar / Closing the abdominal wall: what technique and type of suture to use  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Introducción: El cierre de la pared abdominal es un procedimiento frecuente en la práctica de los cirujanos generales. El tipo de cierre y el material de sutura en la mayoría de los casos se realizan y escogen en forma empírica. El presente estudio valora la mejor evidencia disponible sobre la técni [...] ca para el cierre de la fascia abdominal y el tipo de sutura. Métodos: Se realizó una búsqueda sistemática de la literatura y se evaluaron los artículos de más alta calidad (revisiones sistemáticas). Los resultados se analizaron particularmente. Resultados: La mejor técnica de sutura de la fascia abdominal es aquella con puntos continuos con material de absorción lenta (polidioxanona) o no absorbible (polipropileno), los cuales tienen índices de hernia incisional menores que las suturas de absorción rápida. Conclusiones: Es recomendable utilizar sutura de material de absorción lenta o no absorbible para el cierre de la pared abdominal. Abstract in english Introduction: Closure of the abdominal wall is a frequently performed procedure in general surgical practice. The type of closure and the suture material are often chosen on empirical bases. The present study evaluates the best evidence available regarding the technique of closure of the abdominal w [...] all and the best suture material to be used. Methods: A systematic literature search was undertaken and the best quality articles (systematic reviews) were analyzed. Results: The best technique appears to be the closure with interrupted sutures of slow absorption (polydioxanone) or non absorbable (polypropylene) material, which exhibit lower recurrence rates that those observed with materials of rapid absorption. Conclusions: It is recommended to utilize interrupted sutures of slow absorption or non absorbable material for closing the abdominal wall.

Carlos, Lehmann; Álvaro, Sanabria; Eduardo, Valdivieso; Gabriel, Gómez.

136

Cierre de la pared abdominal: qué técnica y qué sutura se deben usar Closing the abdominal wall: what technique and type of suture to use  

Directory of Open Access Journals (Sweden)

Full Text Available Introducción: El cierre de la pared abdominal es un procedimiento frecuente en la práctica de los cirujanos generales. El tipo de cierre y el material de sutura en la mayoría de los casos se realizan y escogen en forma empírica. El presente estudio valora la mejor evidencia disponible sobre la técnica para el cierre de la fascia abdominal y el tipo de sutura. Métodos: Se realizó una búsqueda sistemática de la literatura y se evaluaron los artículos de más alta calidad (revisiones sistemáticas. Los resultados se analizaron particularmente. Resultados: La mejor técnica de sutura de la fascia abdominal es aquella con puntos continuos con material de absorción lenta (polidioxanona o no absorbible (polipropileno, los cuales tienen índices de hernia incisional menores que las suturas de absorción rápida. Conclusiones: Es recomendable utilizar sutura de material de absorción lenta o no absorbible para el cierre de la pared abdominal.Introduction: Closure of the abdominal wall is a frequently performed procedure in general surgical practice. The type of closure and the suture material are often chosen on empirical bases. The present study evaluates the best evidence available regarding the technique of closure of the abdominal wall and the best suture material to be used. Methods: A systematic literature search was undertaken and the best quality articles (systematic reviews were analyzed. Results: The best technique appears to be the closure with interrupted sutures of slow absorption (polydioxanone or non absorbable (polypropylene material, which exhibit lower recurrence rates that those observed with materials of rapid absorption. Conclusions: It is recommended to utilize interrupted sutures of slow absorption or non absorbable material for closing the abdominal wall.

Carlos Lehmann

2007-06-01

137

Uniaxial nonlinear viscoelastic viscoplastic modeling of polypropylene  

Science.gov (United States)

This paper presents the application of the Schapery viscoelastic and the Perzyna viscoplastic models to strain recovery data of polypropylene. In a previous study, the recovery of strain after monotonic uniaxial tensile loading was measured to gather information on the viscoelasticity and viscoplasticity. The viscoplastic strains from several load histories were determined and are used to calibrate the viscoplastic model. The parameters of the one-dimensional Schapery model are then found by nonlinear optimization using the strain recovery history. The prediction of stress relaxation and creep behavior is investigated.

Tscharnuter, Daniel; Jerabek, Michael; Major, Zoltan; Pinter, Gerald

2012-08-01

138

"Tissue-drag" with polyglycolic acid (Dexon) and polyglactin 910 (Vicryl) sutures in strabismus surgery.  

Science.gov (United States)

The new absorbable synthetic sutures, polyglycolic and (Dexon) and Polyglactin 910 (Vicryl), are excellent sutures for strabismus surgery, but they have a bothersome tendency to attract adjacent tissue (tissue-drag). This difficulty is found especially with the 5-0 size suture, less so with the 6-0 size suture, and minimally with the 7-0 size suture. The presence and number of short, stubbly, protuberant strands (hooklets) seen on the surface of these sutures under high magnification correlates with the lack of ease with which the sutures pass through tissue. Other factors involved in tissue-drag include the crevices between braids in these sutures and the fiber-tissue friction due to the innate nature of the suture materials. Sutures which pass with ease through tissue, such as catgut and nonabsorbable sutures, are seen to have smooth surfaces under high magnification. Coating the 5-0 and 6-0 Dexon and Vicryl sutures to smooth their surfaces and reduce tissue-drag was ineffective with isotonic saline solution, minimally to moderately effective with glycerine and with methylcellulose and polyvinyl alcohol solutions, but highly effective with peanut and sesame oils. Though tissue-passage of Dexon and Vicryl sutures was much improved by coating with oil and entirely satisfactory, it still was not quite as good as with catgut. Clinically, the oil did not compromise the knot security or ease of handling of the sutures. No unusual postoperative reaction was seen with the use of the oiled sutures. Although oiling the synthetic absorbable sutures at time of surgery is effective, we recommend that suture manufacturers reduce the tissue-drag of synthetic absorbable sutures either by smoothing the surface in the manufacturing process or by developing an absorbable coating applied to the sutures during manufacture. PMID:1018225

Apt, L; Henrick, A

1976-01-01

139

Effect of recombinant human platelet-derived growth factor-BB-coated sutures on Achilles tendon healing in a rat model: A histological and biomechanical study  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Repairing tendon injuries with recombinant human platelet-derived growth factor-BB has potential for improving surgical outcomes. Augmentation of sutures, a critical component of surgical tendon repair, by coating with growth factors may provide a clinically useful therapeutic device for improving tendon repair. Therefore, the purpose of this study was to (a coat Vicryl sutures with a defined dose of recombinant human platelet-derived growth factor-BB without additional coating excipients (e.g. gelatin, (b quantify the recombinant human platelet-derived growth factor-BB released from the suture, and (c use the recombinant human platelet-derived growth factor-BB-coated sutures to enhance tendon repair in a rat Achilles tendon transection model. Methods: Vicryl sutures were coated with 0, 0.3, 1.0, and 10.0 mg/mL concentrations of recombinant human platelet-derived growth factor-BB using a dip-coating process. In vitro release was quantified by an enzyme-linked immunosorbent assay. Acutely transected rat Achilles tendons were repaired using one of the four suture groups (n = 12 per group. Four weeks following repair, the tensile biomechanical and histological (i.e. collagen organization and angiogenesis properties were determined. Results: A dose-dependent bolus release of recombinant human platelet-derived growth factor-BB occurred within the first hour in vitro, followed by a gradual release over 48 h. There was a significant increase in ultimate tensile strength (p < 0.01 in the two highest recombinant human platelet-derived growth factor-BB dose groups (1.9 ± 0.5 and 2.1 ± 0.5 MPa relative to controls (1.0 ± 0.2 MPa. The modulus significantly increased (p = 0.031 with the highest recombinant human platelet-derived growth factor-BB dose group (7.2 ± 3.8 MPa relative to all other groups (control: 3.5 ± 0.9 MPa. No significant differences were identified for the maximum load or stiffness. The histological collagen and angiogenesis scores were comparable in all groups, although there was a trend for improved collagen organization in the recombinant human platelet-derived growth factor-BB-treated groups (p = 0.054. Conclusions: The results of this study suggest that recombinant human platelet-derived growth factor-BB can be used to reproducibly coat Vicryl sutures and improve remodeling in a rat Achilles tendon transection model by significantly decreasing the resulting cross-sectional area, thus improving the material properties of the repaired tendon.

Stephen H Cummings

2012-07-01

140

Single-helix crystal in atactic polypropylene  

Science.gov (United States)

The conformational arrangement of a locally stereoregular sequence of atactic polypropylene (aPP) was investigated via X-ray diffraction, thermal analysis, and infrared spectroscopy. Since the aPP used was an isotactic-rich sample, the X-ray diffraction pattern showed the typical profile of an ?-iPP (isotactic polypropylene) crystal, indicating that the crystal is constructed from locally stereoregular sequences. Even for a sample with low stereoregularity (meso pentad = 16%), small peaks due to ?-iPP crystals were observed. The melting temperature of aPP was reduced compared with an ?-iPP crystal. This corresponds to a shortening of the lamellar thickness. Helical units from chloroform insoluble and soluble fractions having meso pentads of 0.64 and 0.16, respectively, were composed of 3.5 and 1.2 repeating units, respectively. Such short conformational order was also confirmed by infrared spectroscopy. In general, a conformationally sensitive band is observed over a critical regular sequence (n). For the chloroform soluble fraction, a 977 cm-1 band for n = 5 was observed, but the typical 998 and 841 cm-1 bands for n = 11-12 and 13-15, respectively, were not observed. This signals that the regular conformation consists of 1-2 repeating units. It is concluded that a short conformational order (about 1-2 helical units) can construct the crystalline unit for aPP.

Nakaoki, Takahiko; Fukui, Daisuke

2013-11-01

 
 
 
 
141

Improved oil spill recovery using polypropylene fabric  

International Nuclear Information System (INIS)

An active boom for recovering oil spills was tested in a tank with diesel fuel, a motor oil, and a heavy crude oil. The boom consisted of a porous pipe wrapped in a polypropylene fabric to which a vacuum was applied. The diesel was recovered at a rate of 29 gal/h per ft2 of fabric surface area (GHPF) using a vacuum of 17 in. of water without any entrained water. The motor oil was recovered at a rate of 2.5 GHPF using a vacuum of 20 in. of water without any entrained water. The crude oil test at a vacuum of 8 in. Hg also resulted in a fluid recovery rate of 2.5 GHPF, but half of the recovered fluid was water. The results suggest that a device presenting a large surface area of polypropylene fabric to a spill of light or medium oil will separate the oil from the water. Uses for the device extend to other situations where oil-water separation is required. 1 ref., 4 figs., 3 tabs

142

Preparation and Characterization of Polypropylene / MWCNT Dispersions  

Science.gov (United States)

Dispersions of multiwall carbon nanotubes in polypropylene are prepared via melt batch mixing and solid-state shear pulverization, and characterized via linear viscoelastic measurements, SEM, polypropylene crystallization kinetics, electrical conductivity and dynamic mechanical analysis. Increasing the intensity or duration of the melt mixing leads to higher dispersion, evidenced by increases in a low-frequency elastic plateau and accelerated PP crystallization kinetics attributed to more effective heterogeneous nucleation. The sample prepared by pulverization exhibits faster crystallization kinetics than any of the melt blended samples, but in contrast shows no measurable low frequency elastic plateau. Electrical conductivity measurements similarly show higher conductivity in melt blended samples. This may be attributable to scission of the nanotubes during pulverization, such that even well dispersed tubes cannot form an entangled network at a given concentration. At the same time, pulverized composites show marked increase in stiffness at low loadings, indicating that tube scission due to pulverization is not catastrophic. Conversely, long mixing times required in melt blending cause substantial thermal degradation of the polymer matrix with a corresponding loss of mechanical properties.

Pujari, Saswati; Burghardt, Wesley; Ramanathan, Thillaiyan; Brinson, L. Catherine; Kasimatis, Kosmas; Torkelson, John

2008-03-01

143

Sutures and shear zones in the Arabian-Nubian Shield  

Science.gov (United States)

Deformational belts in the Arabian-Nubian Shield (ANS) are divided into: (1) those associated with sutures, both arc-arc and arc-continental; and (2) post-accretionary structures which include north trending shortening zones and northwest trending strike-slip faults. The arc-arc sutures manifest collision between arc terranes at -800-700 Ma. They are orientated east to northeast in the northern part of the ANS and north to north-northeast in the south. North or south verging ophiolitic nappes are associated with the east to northeast trending sutures. These nappes were steepened by upright folds associated with the final stages of collision between terranes. East or west verging ophiolitic nappes are associated with the north to north-northeast trending sutures. These were deformed by upright folds and strike-slip faults related to oblique collision between terranes and/or post-accretionary deformations. The arc-continental sutures define the eastern and western boundaries of the ANS and are marked by north trending deformational belts which accompanied collision of the ANS with east and west Gondwana at -750-650 Ma. The post-accretionary structures were developed between -650-550 Ma due to continued shortening of the ANS. This produced north trending shortening zones which offset the east to northeast trending sutures in the northern part of the ANS but were superimposed as co-axial deformation on the north to north-northeast trending sutures in the south. The shortening deformation culminated with the development of northwest trending strike-slip faults and shear zones.

Abdelsalam, M. G.; Stern, R. J.

1996-10-01

144

Midwives conducting perineal repair: The Danish Suture Trial  

DEFF Research Database (Denmark)

Midwives conducting perineal repair: The Danish Suture Trial.     Background Suture techniques and materials for repair of 2nd degree perineal lacerations and episiotomies have been tested in several clinical trials. Danish midwives and obstetricians have developed a new, simple and time-efficient suture technique which needed systematic evaluation. Objective To compare two standardized suture techniques for perineal repair of 2nd degree perineal lacerations or episiotomies. Design and setting A double-blind randomised clinical trial conducted in Aarhus University Hospital, Denmark. Initiated August 2004, enrolment of patients finished October 2005. Sample size: 400. Inclusion: Healthy primipara sustaining a 2nd degree perineal laceration or an episiotomy following vaginal birth. Perineal repair was carried out by a midwife. Exclusion: Lacerations involving the sphincter ani, post partum haemorrhage >1000 ml, Diabetes, mental disorders. Both suture techniques were 2-layered using a polyglactin910 multifilament suture (Vicryl Rapid or Vicryl). Treatment A was a continuous suture technique and treatment B was interrupted, inverted stitches. Primary outcomes: Perineal pain and wound healing assessed day 1-2 and 10 post partum. Secondary outcomes: patient satisfaction with wound healing, need for secondary repair, superficial pain during intercourse.   Data management: Double entry of all data and intention-to-treat analysis.   Results The follow up rate was 97%. Baseline data were evenly distributed between the two treatment groups. Major difference in pain and healing was observed between spontaneous lacerations and episiotomies. Follow up 6 months post partum will be finished by April 2006.   Conclusion Primary results will be presented on the NFOG Congress in Göteborg, May 2006.

Kindberg, Sara

2007-01-01

145

Study on thermal decomposition of calix[4]arene and its application in thermal stability of polypropylene  

International Nuclear Information System (INIS)

Thermal decomposition kinetics of calix[4]arene (C4) was investigated using thermogravimetric analysis (TGA) and derivative of TG curve (DTG). TG experiments were carried out under static air atmosphere with nominal heating rates of 1.0, 2.5, 5.0 and 10.0 K/min. Model-fitting methods and model-free methods such as Friedman and Ozawa-Flynn-Wall methods were employed to evaluate the kinetic parameters such as activation energy (Ea), exponential factor (ln A) and reaction order (n). To determine the antioxidant property of C4 the non-isothermal kinetics of polypropylene (PP) with C4 as additive was studied. The FTIR, ESR and 13C NMR CP-MAS techniques were used to propose the decomposition mechanism of C4 in the presence of PP.

146

Nanoparticle effects during pressure-induced crystallization of polypropylene  

International Nuclear Information System (INIS)

We describe here phase and morphological changes that are induced when polypropylene containing dispersion of nanoclay is isothermally crystallized in the pressure range of 0.1-200 MPa. To delineate and separate the effects of applied crystallization pressure from nanoparticle effects, a relative comparison is made between neat polypropylene and polypropylene containing dispersion of nanoclay under similar experimental conditions. The significant finding is that nanoparticles of clay interact with the host polypropylene in a manner such that they alter the structural morphology of ?- and ?-crystals of polypropylene presumably via nanoparticle interface driven evolution. Interestingly, nanoclay promotes the formation of ?-phase at low pressure, which is expected to have significant bearing on physico-chemical and mechanical properties. The equilibrium melting point measurements point to thermodynamic interaction between nanoclay and polypropylene, which is supported by the change in glass transition temperature and modification of absorption bands of polypropylene between 995 and 973 cm-1 corresponding to tertiary methyl skeletal in Fourier transform infrared spectrum

147

Nanoparticle effects during pressure-induced crystallization of polypropylene  

Energy Technology Data Exchange (ETDEWEB)

We describe here phase and morphological changes that are induced when polypropylene containing dispersion of nanoclay is isothermally crystallized in the pressure range of 0.1-200 MPa. To delineate and separate the effects of applied crystallization pressure from nanoparticle effects, a relative comparison is made between neat polypropylene and polypropylene containing dispersion of nanoclay under similar experimental conditions. The significant finding is that nanoparticles of clay interact with the host polypropylene in a manner such that they alter the structural morphology of {alpha}- and {gamma}-crystals of polypropylene presumably via nanoparticle interface driven evolution. Interestingly, nanoclay promotes the formation of {gamma}-phase at low pressure, which is expected to have significant bearing on physico-chemical and mechanical properties. The equilibrium melting point measurements point to thermodynamic interaction between nanoclay and polypropylene, which is supported by the change in glass transition temperature and modification of absorption bands of polypropylene between 995 and 973 cm{sup -1} corresponding to tertiary methyl skeletal in Fourier transform infrared spectrum.

Yuan, Q. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Rajan, V.G. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Department of Chemical Engineering, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Misra, R.D.K. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Department of Chemical Engineering, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States)], E-mail: dmisra@louisiana.edu

2008-09-25

148

Ultimate tensile strength of gamma irradiated human scleral sutures.  

Science.gov (United States)

Scleral sutures were prepared by hand from the equatorial region of 53 paired donor eyes. The weakening produced by two doses of gamma Co-60 radiation (2.7 and 4.0 Mrads) was compared using measurements of tensile strength; the strength of unirradiated scleral sutures was also measured, for comparison. The three variables of tensile strength, viz. Breaking Elongation, Breaking Load, and Work of Rupture was determined for each suture. As compared to unirradiated sutures, Breaking Elongation decreased on irradiation (P less than 0.01), but the two doses of irradiation were not statistically significant (P greater than 0.05); Breaking Load increased on irradiation (P less than 0.01), but the two doses of irradiation were again not significant (P greater than 0.05). Only 4.0 Mrads irradiated scleral sutures, as compared to unirradiated ones, showed a statistically significant reduction (P less than 0.01) for Work of Rupture. No definite relationships were found by regression analysis among the tensile strength variables and the independent variables of sex and various storage times for the 4.0 Mrad data. Work of Rupture showed a negative relationship to the age of donors, though the change with age was small. PMID:890593

Cutz, A; Reid, D B; Basu, P K

1977-07-01

149

Complexity of serrated sutures of a human skull  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: to reveal the variability mechanism of complexity of serrated sutures of a human skull in the correlation with cranial form. Materials and methods. Researches of 253 arches of male and female skulls of patients at the age of 1 day-105 years without signs of cranial trauma or skeletal systemic diseases with absence of morphological signs of increase of intracranial pressure. Minimal (Min and maximal (Max values, average arithmetic (M, a mistake of average arithmetic (m have been studied. For definition of reliability of average size difference parametrical and non-parametric statistical criteria were used: parametrical criterion (t-criterion of Student applied for parameters submitting to the law of normal distribution (Lakin G. R, 1990. Distinctions of average arithmetic size were considered statistically authentic from 95% (p<0,05 a level of correct judgement (Plokhinskiy N.A., 1970. Results. On the surface of the arch lambdoid and coronal sutures in male skulls and lambdoid and sagittal sutures in female were found out to be of the greatest degree of complexity. Conclusion. The increase of complexity of sutures has been observed in children and adolescents; the directed asymmetry of sutures form is absent

Kochenkova ?.V.

2011-09-01

150

Punto interdomal en técnica cerrada / Interdomal suture in closed approach  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish El manejo de la punta nasal es un elemento clave en toda rinoplastía. Las primeras técnicas empleadas sacrificaban la estructura del arco alar con resultados posoperatorios indeseables. En la era moderna de la rinoplastía, el manejo de la punta nasal se enfocó en remodelar, preservar y reposicionar [...] los cartílagos alares mediante el uso de suturas. El punto interdomal es una sutura en forma de ocho o loop simple desde la porción más anterior de un domo hacia el contralateral uniendo la región más alta de las cruras mediales. En el presente artículo se realiza una revisión del uso de puntos de suturas en el manejo de la punta nasal, se describen las características del punto interdomal en técnica cerrada y se muestran sus resultados en una serie de casos. Abstract in english The nasal tip surgery is a key element in rhinoplasty. The first techniques employed sacrificed the alar arch structure with undesirable postoperative results. In the modern era of rhinoplasty, nasal tip surgery focused on reshaping, preserving and repositioning the alar cartilages using reversible [...] sutures. The interdomal suture is a figure-eight or simple loop suture placed from the most anterior portion of one dome to the contralateral joining the highest region of the medial crura. This article reviews the use of suture techniques in nasal tip reshaping and describes the interdomal suture in closed approach and its results in a clinical series.

Roberto, Arias A; Leandro, Rodríguez H; Mónica, Rojas O; Mariana, Bogado C.

151

Effects of gamma irradiation on polypropylene, polypropylene + high density polyethylene and polypropylene + high density polyethylene + wood flour  

Energy Technology Data Exchange (ETDEWEB)

The effect of the gamma-irradiation on the mechanical properties of the composites, Polypropylene (PP), PP+high density Polyethylene (HDPE), PP+ HDPE+wood flour, where HDPE is virgin and recycled, was studied. This paper discusses the behavior of the composites after exposure to various doses of gamma irradiation (1-7 MRads) in the presence of oxygen. The dependence of mechanical properties on the integral dose for a constant dose rate of 0.48 MRads/h confirms the influence of the irradiation. Strong effects on the elongation at break and break strength is noticed. The mathematical analysis suggests for the PP+r-HDPE a bimolecular process of the elongation at break. On the order hand, for the PP+HDPE a complex process is represented for a three exponential equation. (orig.)

Reyes, J.; Albano, C.; Davidson, E.; Poleo, R. [Universidad Central de Venezuela, Caracas (Venezuela). Escuela de Quimica; Gonzalez, J.; Ichazo, M. [Universidad Simon Bolivar, Dept. de Mecanica, Caracas (Venezuela); Chipara, M. [Research Institute for Electrotechnics, Bucharest (Romania)

2001-04-01

152

Effects of gamma irradiation on polypropylene, polypropylene + high density polyethylene and polypropylene + high density polyethylene + wood flour  

International Nuclear Information System (INIS)

The effect of the gamma-irradiation on the mechanical properties of the composites, Polypropylene (PP), PP+high density Polyethylene (HDPE), PP+ HDPE+wood flour, where HDPE is virgin and recycled, was studied. This paper discusses the behavior of the composites after exposure to various doses of gamma irradiation (1-7 MRads) in the presence of oxygen. The dependence of mechanical properties on the integral dose for a constant dose rate of 0.48 MRads/h confirms the influence of the irradiation. Strong effects on the elongation at break and break strength is noticed. The mathematical analysis suggests for the PP+r-HDPE a bimolecular process of the elongation at break. On the order hand, for the PP+HDPE a complex process is represented for a three exponential equation. (orig.)

153

Degradation study of polypropylene (PP and bioriented polypropylene (BOPP in the environment  

Directory of Open Access Journals (Sweden)

Full Text Available Polymers are vastly employed for numerous purposes in different industrial segments and generate soaring quantities of discarding in the environment. This research analyzed the degradability/biodegradability of polypropylene films (PP and Bioriented polypropylene (BOPP polymers after 11 months interred in the São Giácomo landfill in Caxias do Sul. Comparing the buried PP film to a sample of virgin PP, two peaks of degrading activity appeared at the TG curve as well as structure modification typified by occurrence of new absorption bands at FTIR, which can be credited to changes in crystallinity. Thermal analysis carried out on the buried PP and BOPP showed decreases in the percentage of crystallinity due to chain scission. The major reduction was observed in the PP, since its crystallinity is a consequence of polymerization instead of chain orientation processes, as in BOPP. Cracks and erosion of the polymer surface were detected in both PP and BOPP, indicating degrading processes by microorganisms.

Carina Longo

2011-12-01

154

Prosthetic abdominal wall hernia repair in emergency surgery: from polypropylene to biological meshes  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract The use of nonabsorbable prosthetic materials such as polypropylene, polyester, and ePTFE, have expanded and are now widely used in reparative surgery for abdominal wall hernias. There are still difficulties to find correct indication for prosthetic implant in emergency hernia surgery: as a matter of fact there is still a great debate if to use non-absorbable prostheses in potentially or truly infected operating fields [e.g. after intestinal resections]. All these problems can be avoided with the use of absorbable prosthetic materials such as those composed of lactic acid polymers or lactic and glycolic acid copolymers: however, the use of these absorbable prosthesis exposes the patient to a rapid and inevitable hernia recurrence. It is important to remember that prosthetic repair has been proven to have a significant less risk of recurrence than repair with direct sutures. Recently, new "biologic" prosthetic materials have been developed and proposed for the clinical use in infected fields. These materials can be called "remodeling" for the way by which they are replaced after their placement within the patient. The "remodeling" process is made possible through a process of incorporation, where a reproduction of a site-specific tissue similar to the original host tissue is created.

Campanelli G

2008-12-01

155

Electrophysical Properties of Composites Based on Atactic Polypropylene  

Science.gov (United States)

Results of investigations of the dielectric permittivity and dielectric loss tangent are presented for a wide frequency range. Physical and chemical properties of modified atactic polypropylene are investigated and experimental parameters of its adhesion to the steel and concrete surfaces are given. It is demonstrated that atactic polypropylene can be used as an electric insulator and water repellent to protect from corrosion metal structures and concrete products used in power engineering. Modification of atactic polypropylene increases the real component of the dielectric permittivity and decreases the dielectric loss tangent, thereby significantly decreasing its conductive properties. This can be used for electric insulation of energy-intensive units.

Debelova, N. N.; Suslyaev, V. I.; Gorlenko, N. P.; Zhuravlev, V. A.; Zav'yalova, E. N.; Dotsenko, O. A.; Zav'yalov, P. B.; Ul'yanova, O. A.

2014-07-01

156

2-hydroxyethyl methacrylate composite - polypropylene mesh for preventing peritoneal adhesions in female dogs / Compósito 2-hidroxietil dimetacrilato-tela de polipropileno para prevenção de aderências peritoneais em cadelas  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese OBJETIVO: Avaliar se o revestimento da face visceral de uma tela de polipropileno com 2-hidroxietil dimetacrilato (p(HEMA)) poderia evitar aderências peritoniais em cadelas. MÉTODOS: Em oito animais (Grupo PP) foram implantadas telas de polipropileno para correção de um defeito do músculo reto abdom [...] inal, enquanto em outro grupo (Grupo PH) fez-se a implantação de uma tela de polipropileno cuja face peritonial foi revestida por 2-hidroxietil dimetacrilato (p(HEMA)). RESULTADOS: Foram observados 62,5% de aderências peritoniais sobre a tela nos animais do Grupo PP, enquanto que no Grupo PH estas não ocorreram, exceto sobre a linha se sutura. CONCLUSÃO: O hidrogel de p(HEMA) foi bem tolerado pelos animais e mostrou-se efetivo na prevenção das aderências viscerais e omentais sobre a tela de polipropileno. Abstract in english PURPOSE: To evaluate whether the lining facing the visceral side of polypropylene mesh made with 2-hydroxyethyl methacrylate (p(HEMA)) hydrogel could avoid peritoneal adhesion in female dogs. METHODS: Eight animals (group PP) had a polypropylene mesh implanted to correct a defect in the rectal abdom [...] inal muscle, whereas in the other group (group PH) the polypropylene mesh was coated with p(HEMA) composite on the surface facing the peritoneal area. RESULTS: Adhesions were observed on the mesh in 62.5% of the PP group. In the PH group adhesions were present only on the suture lines. CONCLUSION: p(HEMA) hydrogel was well tolerated and effective in avoiding visceral and omental adhesions on the surface of the polypropylene mesh.

Marcelo Seixo de Brito e, Silva; Renato Miranda de, Melo; Liliana Borges de, Menezes; Sonia Maria, Malmonge; Leandro Guimarães, Franco; Neusa Margarida, Paulo.

157

2-hydroxyethyl methacrylate composite - polypropylene mesh for preventing peritoneal adhesions in female dogs Compósito 2-hidroxietil dimetacrilato-tela de polipropileno para prevenção de aderências peritoneais em cadelas  

Directory of Open Access Journals (Sweden)

Full Text Available PURPOSE: To evaluate whether the lining facing the visceral side of polypropylene mesh made with 2-hydroxyethyl methacrylate (p(HEMA hydrogel could avoid peritoneal adhesion in female dogs. METHODS: Eight animals (group PP had a polypropylene mesh implanted to correct a defect in the rectal abdominal muscle, whereas in the other group (group PH the polypropylene mesh was coated with p(HEMA composite on the surface facing the peritoneal area. RESULTS: Adhesions were observed on the mesh in 62.5% of the PP group. In the PH group adhesions were present only on the suture lines. CONCLUSION: p(HEMA hydrogel was well tolerated and effective in avoiding visceral and omental adhesions on the surface of the polypropylene mesh.OBJETIVO: Avaliar se o revestimento da face visceral de uma tela de polipropileno com 2-hidroxietil dimetacrilato (p(HEMA poderia evitar aderências peritoniais em cadelas. MÉTODOS: Em oito animais (Grupo PP foram implantadas telas de polipropileno para correção de um defeito do músculo reto abdominal, enquanto em outro grupo (Grupo PH fez-se a implantação de uma tela de polipropileno cuja face peritonial foi revestida por 2-hidroxietil dimetacrilato (p(HEMA. RESULTADOS: Foram observados 62,5% de aderências peritoniais sobre a tela nos animais do Grupo PP, enquanto que no Grupo PH estas não ocorreram, exceto sobre a linha se sutura. CONCLUSÃO: O hidrogel de p(HEMA foi bem tolerado pelos animais e mostrou-se efetivo na prevenção das aderências viscerais e omentais sobre a tela de polipropileno.

Marcelo Seixo de Brito e Silva

2010-08-01

158

Structure-property correlations in polypropylene from metallocene catalysts: stereodefective, regioregular isotactic polypropylene.  

Science.gov (United States)

A series of MAO-activated C(1)-symmetric indenyl-ansa-dithienocyclopentadienyl-based zirconocenes have been used to produce isotactic polypropylenes of medium to high molecular weights, of different degrees of stereoregularity, and free from regioerrors. The effect of the presence of rr defects on the polymorphic behavior and mechanical properties of polypropylene is analyzed. The presence of rr defects induces crystallization of gamma form and of disordered modifications intermediate between alpha and gamma forms. A linear relationship between the amount of gamma form and the average length of isotactic sequences has been found. Samples with low concentration of rr defects, up to 3-4%, present high melting temperatures, in the range 160-130 degrees C, and behave as stiff-plastic materials; sample with higher rr content, in the range 4-6% and melting temperatures around 115-120 degrees C are highly flexible thermoplastic materials, and, finally, samples with concentration of rr defects in the range 7-11% and melting temperatures in the range 80-110 degrees C are thermoplastic elastomers with high strength. The fine-tuning of the chain microstructure, achieved by a tailored design of new metallocene catalysts, has allowed production of new polypropylenes having desired properties, intermediate between those of stiff plastic and elastomeric materials. PMID:15612743

De Rosa, Claudio; Auriemma, Finizia; Di Capua, Annunziata; Resconi, Luigi; Guidotti, Simona; Camurati, Isabella; Nifant'ev, Ilya E; Laishevtsev, Ilya P

2004-12-29

159

Comparison of otoplasty outcomes using different types of suture materials.  

Science.gov (United States)

Prominent ears are the most common congenital deformity. Numerous techniques for the correction of this deformity have been described in the literature, but there is no single technique widely accepted by most surgeons. Usually, more attention is focused on sculpturing or suturing techniques but not on suture material. The aim of this study is to evaluate clinical outcomes after otoplasty for surgical correction of prominent ears with different suture materials for the formation of new antihelical fold. During a 3-year period (2006-2008), 133 patients underwent operative correction of protruding ears in a private plastic surgery center. A total of 100 patients came for the follow-up visits, and the data of these patients were included in further analysis. The surgical technique consisted of scoring of the antihelical cartilage, suturing to recreate the fold of the antihelix (in the manner of Nachlas), and conchal setback procedure according to Furnas technique. According to suture material used for formation of new antihelix fold, the patients were divided into three groups: 4/0 Monocryl group (35 patients, 70 ears; Group 1), 4/0 PDS group (27 patients, 54 ears; Group 2), and 4/0 Mersilene group (38 patients, 7 ears; Group 3). Distances from the temporomastoid surface of the skull to the helix border in the upper, middle, and lower parts of the ear were measured before surgery and 6 months following surgery, and these measures were compared among groups. In addition, early and late complications were analyzed. There were 48 men and 52 women, and the median age was 20 years. The groups were matched for age, sex, and protrusion degree. No statistically significant differences were found comparing the groups of different suture material by skull-helical rim distance before operation. Comparison of skull-helical rim distance among groups after surgery showed that this distance in the medial and lower parts of the ear was the same in all groups, but this distance was smaller in the upper part of the ear in the Mersilene group; however, this difference was not statistically significant. Three patients in the Monocryl group (6 ears, 8.57%) and 3 patients in the PDS group (6 ears, 11.11%) had unsatisfactory aesthetic outcome because of recurrence of protrusion in the upper part of the ear. All of them underwent reoperation. In the Mersilene group, no recurrence was documented, but suture extrusion occurred in one patient (2 ears, 2.63%), and the sutures were removed. In our experience, formation of new antihelical fold with a 4/0 Mersilene suture resulted in the lowest rates of late complications. Using this type of suture material, some suture extrusions occurred, but this problem was easily solved by removing sutures. No recurrences of protrusion were documented in this group; therefore, no revision surgeries were necessary. PMID:20480848

Maslauskas, Kestutis; Astrauskas, Tautrimas; Viksraitis, Saulius; Samsanavidius, Donatas

2010-01-01

160

Superficial wound closure complications with barbed sutures following knee arthroplasty.  

Science.gov (United States)

As quality measures may be increasingly used in knee surgery reimbursement, an important focus in outcome assessment will shift toward minimizing complications and increasing efficiency in knee arthroplasty reconstruction. The purpose of this study was to evaluate the efficacy of barbed, absorbable sutures in closure of the longitudinal surgical incision following knee arthroplasty, using post-operative complication occurrences. In 416 operations, primary outcomes assessed were deep infection, superficial infection, dehiscence, or stitch abscesses. Secondary outcomes included self-limiting eschar, severe effusion, arthrofibrosis, and keloid formation. Evaluation of overall primary outcomes showed a higher rate of wound complications using barbed sutures (P < 0.001). With increased rates of infection and overall closure related complications, this study shows that barbed suture use for superficial closure after knee arthroplasty should be avoided. PMID:24184326

Campbell, Abigail L; Patrick, David A; Liabaud, Barthelemy; Geller, Jeffrey A

2014-05-01

 
 
 
 
161

Suture Retention Strength of Expanded Polytetrafluoroethylene (ePTFE Graft  

Directory of Open Access Journals (Sweden)

Full Text Available

Our meticulous investigation of ePTFE graft breakage when a wire placed at the edge of an ePTFE graft was pulled, revealed that, depending on the breakage pattern, a break starts much earlier than the peak suture retention strength, which is the current international indicator for anastomotic-site break strength. Furthermore, the breakage patterns differ based on the thickness of the wire and the fiber direction of the ePTFE graft. Based on these findings, we advocate measuring the peak suture retention strength using 0.10-mm sutures and a standardized wire thickness in order to assess the anastomotic retention strength of ePTFE grafts.

Mine,Yoshinari

2010-04-01

162

Effect of Electron Irradiation on Polypropylene Films  

International Nuclear Information System (INIS)

Effects of both electron beam irradiation on the properties of polypropylene (PP) films and the irradiation on the different layers of a multilayer PP film are studied. A Fourier transform infrared spectroscope was used to investigate the chemical structure of the films. The results showed that the chemical properties of the first layer were improved, that is, more functional groups responsible for dye ability and hydrophilicity of the film were produced on its surface, while noticeable improvement was not detected on the surface of other layers. This was also confirmed by testing the dye ability of the layers. However, the results obtained by atomic force microscopy showed that the electron irradiation caused some topographical changes, not only on the surface of the first layer but also on the others. (low temperature plasma)

163

Electron beam modification of polypropylen fabrics  

International Nuclear Information System (INIS)

In this study, Electron bombardment with the energy of 10-40 Kev and different period of time has been carried out. Electron beam processing of polypropylene (PP) fabrics is found to promote significant changes in physical and chemical properties. The obtained data show that, electron beam processing of PP fabrics allows an adjustable modification of their surface properties. The functional groups on the surface of samples were examined using FTIR spectrometer. Moreover, dyeing properties for treated fabrics has been tested. Relative increase in color strength has been achieved. Morphology of samples was examined by Scanning Electron Microscopy (SEM). The absorption times and contact angle were utilized to analyze the result of the treated samples. This process is promising for the compatibilization of PP fiber and matrix with various compound in blends and production of multilayered composites for versatile applications such as laminates and supported compound. (author)

164

POLYPROPYLENE/CLAY NANOCOMPOSITES: SYNTHESIS AND CHARACTERIZATION  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Polypropylene nanocomposites were synthesized by using the method of mixing in the molten state. Nanocomposites were obtained in twin-screw co-rotating extruders and the nanocomposites were prepared with percentage of nanoclay (C2) from 5 wt-%, with and without compatibilizer agent (PP-g-MA). The th [...] ermal (DSC, TGA), morphology (XRD, TEM), and dynamical mechanical (DMA) properties of the nanocomposites were characterized. All nanocomposites prepared are in intercalated state as corroborated by XRD and TEM. The Tm and Xc were not affected by the presence of clay, PP-g-MA, or processing support. The incorporation of clay and compatibilizer agent increases the thermal stability and heat deflection temperature (HDT).

MÓNICA A, PÉREZ; BERNABÉ L, RIVAS; SADDYS M, RODRÍGUEZ; ÁLVARO, MALDONADO; CAROLA, VENEGAS.

2010-12-01

165

Surface properties of polypropylene/organoclay nanocomposites  

Energy Technology Data Exchange (ETDEWEB)

Influence of nanoclay amount on surface properties of the nanocomposites was investigated using Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement, scanning electron microscopy (SEM) and transmission spectroscopy (TS). Polypropylene based nanocomposites containing various loads of nanoclay were prepared by melt compounding. X-ray diffraction (XRD) characterized the dispersion of nanoclay in polymer matrix. AFM and SEM studies have shown increase in surface roughness by raising the amount of nanoclay. Contact angle measurements of the resultant nanocomposites have also shown improvement in wettability related to disperse part of surface tension. POM images illustrated an increase in the number of spherulite simultaneously with a decrease in their size; this result was also supported by differential scanning calorimetry (DSC).

Ataeefard, Maryam, E-mail: m.ataeefard@aut.ac.ir [Faculty of Polymer and Color Engineering, Amirkabir University of Technology, P.O.Box 15875-4413, Tehran (Iran, Islamic Republic of); Moradian, Siamak, E-mail: moradian@aut.ac.ir [Faculty of Polymer and Color Engineering, Amirkabir University of Technology, P.O.Box 15875-4413, Tehran (Iran, Islamic Republic of)

2011-01-01

166

Surface properties of polypropylene/organoclay nanocomposites  

International Nuclear Information System (INIS)

Influence of nanoclay amount on surface properties of the nanocomposites was investigated using Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement, scanning electron microscopy (SEM) and transmission spectroscopy (TS). Polypropylene based nanocomposites containing various loads of nanoclay were prepared by melt compounding. X-ray diffraction (XRD) characterized the dispersion of nanoclay in polymer matrix. AFM and SEM studies have shown increase in surface roughness by raising the amount of nanoclay. Contact angle measurements of the resultant nanocomposites have also shown improvement in wettability related to disperse part of surface tension. POM images illustrated an increase in the number of spherulite simultaneously with a decrease in their size; this result was also supported by differential scanning calorimetry (DSC).

167

Development of radiation-resistant medical polypropylene  

International Nuclear Information System (INIS)

In order to develop a radiation resistant polypropylene (PP) which can be sterilized by gamma radiation for medical use, optimal concentrations of various additives in PP were determined by observing the synergistic effect. The radiation durability of the disposable PP syringes prepared by the formulations was investigated. Their chemical and biological safety was also examined in accordance with the test method on the medical appliances stipulated by the Ministry of Health and Social Welfare. The samples with 0.01 % AO and 0.5 % PL showed sufficient radiation durability to maintain the mechanical strength even after 63 day aging at 60 deg C. The results of the chemical tests and the biological safety tests met the requirements of Korean and US pharmacopoeia. The PP medical products manufactured in accordance with the formulations could be sterilizable by radiation. (author)

168

POLYPROPYLENE/CLAY NANOCOMPOSITES: SYNTHESIS AND CHARACTERIZATION  

Directory of Open Access Journals (Sweden)

Full Text Available Polypropylene nanocomposites were synthesized by using the method of mixing in the molten state. Nanocomposites were obtained in twin-screw co-rotating extruders and the nanocomposites were prepared with percentage of nanoclay (C2 from 5 wt-%, with and without compatibilizer agent (PP-g-MA. The thermal (DSC, TGA, morphology (XRD, TEM, and dynamical mechanical (DMA properties of the nanocomposites were characterized. All nanocomposites prepared are in intercalated state as corroborated by XRD and TEM. The Tm and Xc were not affected by the presence of clay, PP-g-MA, or processing support. The incorporation of clay and compatibilizer agent increases the thermal stability and heat deflection temperature (HDT.

MÓNICA A PÉREZ

2010-12-01

169

Mechanical performance of polyglycolic acid and polyglactin 910 synthetic absorbable sutures.  

Science.gov (United States)

The mechanical performance of polyglycolic acid and polyglactin 910 sutures has been assessed using standardized reproducible tests. The results of these studies demonstrated distinct differences in their performance that can be related, in part, to their structural configuration. The size of the 4-0 polyglactin suture was significantly larger than that of the 4-0 polyglycolic acid suture. Since the strength of any suture is proportional to its cross sectional area, the strength of unknotted and knotted polyglactin 910 sutures was signficantly greater than that of the polyglycolic acid sutures. The strength of both sutures was similarly diminished by the formation of the knot. When these sutures were added to tissue, the breaking strength was even further reduced. The rate of decline in breaking strength of the two absorbable sutures in healing skin wounds was comparable. These absorbable sutures displayed knot security with a two throw square knot, 1 = 1. The ability of these sutures to reach knot break with this knot configuration is characteristic of sutures in which the surface exhibits a high coefficient of friction. Their rough surface also caused them to drag through tissue, making difficult to adjust tension on a continuous running suture. PMID:6272438

Rodeheaver, G T; Thacker, J G; Edlich, R F

1981-12-01

170

The scleral yoke suture for anterior segment surgery.  

Science.gov (United States)

A safe effective method of global control during anterior segment surgery is presented. The method used in 1184 consecutive cases was the scleral yoke traction suture adapted from a method often used in strabismus surgery. The incidence of postoperative ptosis severe enough to require surgical correction is presented in that group as well as in a group of 591 consecutive cataract extractions utilizing the classic superior rectus traction surgery. The principle advantages of this method as compared to the classic superior rectus traction suture are pointed out, with emphasis on the reduction of postoperative ptosis. PMID:3540769

McKenzie, K S; Adams, W L

1986-10-01

171

Familial idiopathic hypertrophic osteoarthropathy and cranial suture defects in children  

International Nuclear Information System (INIS)

Three children with idiopathic hypertrophic osteoarthropathy and cranial suture defects are reported. The syndrome was recognized after birth and in the two oldest siblings, the cranial defects and subperiosteal bone formation resolved almost completely by age 4 and 6 years. The joint swelling and clubbing persisted and mild bone reabsorption of the distal phalanges became apparent at an older age. Two siblings and both parents had normal bone X-rays and no clubbing. This study confirms the association of cranial sutural defects and familial idopathic hypertrophic osteoarthropathy. (orig.)

172

The effects of normal paraffins mobilizers on irradiated polypropylene  

International Nuclear Information System (INIS)

The n-paraffins blended with polypropylene (PP) as mobilizer had been investigated. The effectiveness of mobilizer (n-paraffins) on irradiated polypropylene is dependent on the molecular weight of mobilizer and its content on polypropylene. The n-docosame (n-C22) possesses the best effectiveness of radiation tolerance on PP among the mobilizer paraffins: n-decane (n-C10), n-hexadecane (n-C16), n-docosane (n-C22) and n-hexatriacontane (n-C36). The 2% (w/w) content of a given mobilizer is the most effective at reducing the embrittlement of irradiated PP as evidenced by the elongation at break. The physical properties of polypropylene with mobilizers such as density, Young's modulus, the Fraction of free volume and the weight swelling ratio in p-xylene at room temperature were measured. Above phenomena are related with the constructive of blended PP and demonstrated by its physical properties

173

Effect of ultraviolet radiation (300-400 nanometers) on polypropylene  

International Nuclear Information System (INIS)

Polypropylene discs and shavings were exposed to simulated ambient ultraviolet (UV) radiation (lambda 300-400 nm) for a period equivalent to at least two years of wear within the eye, assuming the eye to be exposed to ambient UV radiation for four hours per day at 1 mW/cm2. The polypropylene and the incubation media were measured by several forms of optical spectroscopy, and there was no photochemical change in either. Where polypropylene discs were exposed to a very high level of UV radiation (greater than 500 W/cm2), they became brittle and discolored within five to ten days. This level of exposure, however, was equivalent to a total of over 20 million joules/cm2, which is at least one million times levels for expected ambient UV exposure to polypropylene within the eye

174

Utilização do laser de argônio na remoção de sutura corneana / Use of argon laser in corneal suture removal  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Descrever a técnica da retirada de sutura em córnea clara, evitando-se o contato da parte externa do fio com o meio intra-ocular e avaliar se esse procedimento evitaria infecções. MÉTODOS: Foi realizado estudo retrospectivo de 1.233 casos de retirada de sutura de mononylon 10.0 em córnea c [...] lara, utilizando-se laser de argônio para cortar o fio, no qual se avaliou a incidência de infecções. RESULTADOS: Em 1.071 olhos, um tiro foi suficiente para cortar o ponto. Em 162 olhos, o tiro do laser atingiu a parte epitelial da sutura, sendo necessários disparos extras para cortar a parte intra-estromal e, assim, retirá-la sem que a parte externa do fio passasse pelo interior da córnea. Não ocorreram complicações após a retirada da sutura. CONCLUSÕES: A técnica utilizada mostrou-se eficaz na remoção das suturas e possivelmente apresenta risco menor de infecção, uma vez que a parte do fio sobrejacente ao epitélio não entra em contato com as camadas mais internas da córnea, nem com a câmara anterior, não tendo sido observado nenhum caso de infecção nesta pesquisa. Abstract in english PURPOSE: To describe the technique of clear-cornea suture removal, that avoids the contact of the external part of the thread with the intraocular medium, and to evaluate whether this procedure would prevent infections. METHODS: A retrospective study of 1.233 cases of clear-cornea mononylon 10.0 sut [...] ure removal, by the use of an argon laser to cut the thread, was performed. Incidence of infection was then assessed. RESULTS: In 1.071 eyes, one shot was enough to cut the stitch. In 162 eyes, the laser shot hit the epithelial part of the suture, making new shots necessary to cut the intrastromal part, and thus to remove it assuring that the outer part of the stitch would not come in to contact with the interior of the cornea. There were no complications after suture removal. CONCLUSIONS: The technique has shown to be effective in suture removal. And, possibly, presents a lower risk for infection, since the external part of the thread does not come in to contact with the innermost parts of the cornea, or with the anterior chamber. No cases of infection have been observed during this research.

Edélcio, Vieira; Vinícius dos Santos Watzl Costa, Lima; Mírian da Silva, Azevedo; Wantuil Ferreira de, Souza Júnior; Roberto Reis Xavier dos, Santos; Ruiz Simonato, Alonso.

175

Polypropylene/graphite nanocomposites by in situ polymerization  

International Nuclear Information System (INIS)

This work presents the synthesis of nanocomposites of polypropylene/graphite by in situ polymerization using metallocene catalyst and graphene nanosheets. Initially was analyzed which of the metallocene catalysts rac-Et(Ind)2ZrCl2 or rac-Me2Si(Ind)2ZrCl2 produces polypropylene with mechanical properties more relevant. Then it were performed the in situ polymerization reactions to obtain the nanocomposites. The polymeric materials were characterized by XRD, DSC, GPC and DMTA. (author)

176

Radiation resistant modified polypropylene; Polipropylen modyfikowany odporny radiacyjnie  

Energy Technology Data Exchange (ETDEWEB)

Radiation technology for production of radiation resistant polypropylene for medical use has been presented. The method consists in radiation induced copolymerization of polypropylene with ethylene and addition of small amount of copolymer of polyethylene and vinyl acetate. The material of proposed composition has a very good mechanical properties and elevated radiation resistivity decided on possibility of radiosterilization of products made of this material and designed for medical use. 3 figs, 3 tabs.

Bojarski, J.; Zimek, Z. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

1997-10-01

177

Study on the Dynamic Performance of Polypropylene Fiber Reinforced Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The dynamic performance of polypropylene fiber reinforced concrete is studied with the SHPB experiment. The relationship of the strain-stress curves are all obtained in the experiment. The crack characteristics of polypropylene reinforced concrete and plain concrete are also investigated. Analyzed the relation between the character on the crack surface of concrete and material properties and the impact pressure. Also the multi-fractal characteristics are given on the crack surface of concrete...

Zhang Ying; Zheng Chunhang; Wu Rujun; Chen Xi; Guoping Jiang

2013-01-01

178

Preparation of Polypropylene/Montmorillonite Nanocomposites Using Ionizing Radiation  

International Nuclear Information System (INIS)

Polymer/clay nanocomposites are new generation materials that bring significant changes in mechanical, thermal and permeation properties of base polymers by low clay loading. In this study, polypropylene/montmorillonite nanocomposites were prepared by melt intercalation method by using batch type mixer. Two polypropylene samples with different melt flow indexes are used as the matrix, maleic anhydride grafted polypropylene (PP-g-MAH), and polypropylene granules oxidized by radiation/ozone are used as compatibilizer and unmodified clay (Na+ montmorillonite, MMT) as the filler. Aim of this study is to examine the effect of different compatibilizers in the mechanical properties of polypropylene composite. Firstly, PP/clay samples were prepared and the effect of clay was examined, then 5, 10, 20kGy oxidized/degraded polypropylenes were used as compatibilizer and, 10 kGy was determined to be the most suitable irradiation dose for the best compatibilizing effect. Polypropylene granules were ozonated until they contained carbonyl groups equivalent to 10kGy oxidized PP, which was checked by FTIR-ATR spectroscopy. UV-visible reflectance measurements were also made on film samples and no significant changes were observed in visible region. Nano structures of some nanocomposites were characterized by PALS (Positron Annihilation Lifetime Spectroscopy) where it was observed that the addition of clay decreased the number of free volume holes and free volume hole radia. The dispersion state of MMT within polymer matrix was analyzed by XRD (X-ray diffraction). Tensile tests were made and the effect of the addition of clay and compatibilizers investigated. At low melt flow index PP, 1% MMT of PP/10kGyPP/MMT nanocomposite showed an increase in E-modulus 26% and in tensile strength 8% as compared to those of pristine PP. In conclusion radiation degraded (chain scissioned and oxidized) PP has been found to show very good compatibilizing effect for the natural montmorillonite/polypropylene composites. (author)

179

21 CFR 878.4494 - Absorbable poly(hydroxybutyrate) surgical suture produced by recombinant DNA technology.  

Science.gov (United States)

...surgical suture produced by recombinant DNA technology. 878.4494 Section 878...surgical suture produced by recombinant DNA technology. (a) Identification...produced by recombinant deoxyribonucleic acid (DNA) technology. The device is intended...

2010-04-01

180

A safety technique for Mitek anchor suture rupture: a useful trick.  

Science.gov (United States)

We propose that the simple method of passing an extra suture through the Mitek anchor eyelet before bony insertion provides a safety net against failure of the preloaded suture and gives extra strength to the core repair. PMID:21802866

Othman, Diaa; Le Cocq, Heather; Majumder, Sanjib

2011-09-01

 
 
 
 
181

Changes in Latitude: A Chandra Study of G296.5+10.0  

Science.gov (United States)

G296.5+10.0 is a supernova remnant at high Galactic latitude, with a distinctive bilateral morphology. Faraday rotation measurements provide evidence for a toroidal magnetic field component that may have been produced in a magnetic wind from the progenitor star. Gamma-ray observations indicate that the remnant has been an efficient particle accelerator. We propose Chandra observations of the remnant to search for evidence of the expected wind composition and density profile, and to determine the nature and spatial distribution of a hard spectral component. We will also investigate an apparent interaction with a small molecular cloud and search for X-ray emission corresponding to observed filamentary structure in the radio.

Slane, Patrick

2014-09-01

182

The Nuclear Network Generator NETGEN v10.0: A Tool for Nuclear Astrophysics  

Science.gov (United States)

We present an updated release of the Brussels Nuclear Network Generator. NETGEN is a tool to help astrophysicists build nuclear reaction networks by generating tables of rates of light-particle (mostly n, p, ?) induced reactions, nucleus-nucleus fusion reactions, and photodisintegrations, as well as ?-decays and electron captures on temperature grids specified by the user. Nuclear reaction networks relevant to a large variety of astrophysical situations can be constructed, including Big-Bang nucleosynthesis, stellar hydrostatic and explosive hydrogen-, helium- and later burning phases, as well as the synthesis of heavy nuclides (s-, r-, p-, rp-, ?-processes). The latest version, NETGEN v10.0, is available on the ULB-IAA website www.astro.ulb.ac.be/Netgen/form.html.

Xu, Y.; Goriely, S.; Jorissen, A.; Takahashi, K.; Arnould, M.

2011-09-01

183

Complexity of suture zones:Example from the Yarlung Zangbo Suture Zone , southern Tibet. (Invited)  

Science.gov (United States)

Decade-long investigation of the Yarlung Zangbo Suture Zone (YZSZ), southern Tibet, has revealed it's high complexity in terms of structure, geochronology and metamorphic and igneous histories. For instance, YZSZ comprises Late Devonian to mid-Miocene rocks, metamorphic intensities vary from high-grade to very-low grade and deformation styles range from ductile to brittle. Late Devonian rocks (363.7 × 1.7 Ma) are alkalic gabbros resulting from activity of a plume active within the Paleo-Tethys basin. Two ophiolite sub-groups are recognized. Sub-group 1 is Mid- to Late Jurassic (150-177 Ma) in age and ill-defined because only few sequences have been found and studied so far. IThis sub-group is probably derived from the destruction of a marginal basin comprising intra-oceanic arc and fore-arc settings. Spontang and Zedong sequences are good examples of this sub-group. Sub-group 2 is Lower Cretaceous (120-130 Ma) and represents the destruction of a marginal basin comprising an arc-back-arc system. These ophiolites are spatially associated with ophiolitic mélanges and flysch respectively representing the reworking of the Cretaceous ophiolites and Indian continental margin and the Neo-Tethyan ocean floor although such affinities need clarification. Most ophiolitic sequences belong to sub-group 2 such as Xiugubagu, Saga, Xigaze. Amphibolite and garnet amphibolite blocks (123-130 Ma) found within the ophiolitic mélange share similar geochemical attributes with sub-group 2 ophiolites. Their protoliths were probably generated within back-arc spreading center and metamorphosed in a subduction zone at depth around 50 km. Some radiometric ages suggest events at 80 Ma and 90 old represent the entry of Indian continental margin into the intra-oceanic subduction zone and/or obduction of ophiolites. However these ages seem to be very rare throughout the whole suture zone and are therefore considered as resulting from local metamorphic events. Some alkaline igneous rocks (131-144 Ma) within the flysch could represent Kerguelen OIB plume products. The study of igneous blocks and the sedimentary matrix suggests a continuous passive margin model. The Miocene (11-17 Ma) post-collisional ultrapotassic rocks discovered in 2006-2007 result from the collapse of the Tibet Plateau accommodated by E-W extensional regime. They carry crustal xenoliths of metamorphic origins representing a window through the deep crustal section underlying the YZSZ. The geochemistry of these shoshonitic intrusives shows strong subduction components resulting from the metasomatism of the mantle wedge over the subduction zones accommodating the closure of Neo-Tethys basin. ?Nd values suggest the source reservoir for these magmatic rocks has mostly Asian late Precambrian affinity. YZSZ contains features related to the interplay between India and Eurasian plates once separated by the large Tethys Ocean or one of associated smaller basin such as the Neo-Tethys basin. However, the complexity of the YZSZ and the diversity of rock types call for a redefinition of the suture zone to include such a mosaic of terranes now tectonically adjacent within this narrow orogenic collisional zone.

Hebert, R.; Guilmette, C.

2013-12-01

184

Comparison of the cheese-wiring effects among three sutures used in rotator cuff repair  

Science.gov (United States)

Purpose: The goal of this study was to compare the cheese-wiring effects of three sutures with different coefficients of friction. Materials and Methods: Sixteen human cadaveric shoulders were dissected to expose the distal supraspinatus and infraspinatus muscle tendons. Three sutures were stitched through the tendons: #2 Orthocord™ suture (reference #223114, DePuy Mitek, Inc., Raynham, MA), #2 ETHIBOND* EXCEL Suture, and #2 FiberWire® suture (FiberWire®, Arthrex, Naples, FL). The sutures were pulled by cyclic axial forces from 10 to 70 N at 1 Hz for 1000 cycles through a MTS machine. The cut-through distance on the tendon was measured with a digital caliper. Results: The cut-through distance in the supraspinatus tendons (mean ± standard deviation, n = 12) were 2.9 ± 0.6 mm for #2 Orthocord™ suture, 3.2 ± 1.2 mm for #2 ETHIBOND* suture, and 4.2 ± 1.7 mm for #2 FiberWire® suture. The differences were statistically significant analyzing with analysis of variance (P = 0.047) and two-tailed Student's t-test, which showed significance between Orthocord™ and FiberWire® sutures (P = 0.026), but not significant between Orthocord™ and ETHIBOND* sutures (P = 0.607) or between ETHIBOND* and FiberWire® sutures (P = 0.103). Conclusion: The cheese-wiring effect is less in the Orthocord™ suture than in the FiberWire® suture in human cadaveric supraspinatus tendons. Clinical Relevance: Identification of sutures that cause high levels of tendon cheese-wiring after rotator cuff repair can lead to better suture selection.

Lambrechts, Mark; Nazari, Behrooz; Dini, Arash; O'Brien, Michael J.; Heard, Wendell M. R.; Savoie, Felix H.; You, Zongbing

2014-01-01

185

Prospective randomized controlled trial investigating the type of sutures used during hepatectomy  

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AIM: To determine whether absorbable sutures or non-absorbable sutures are better in preventing surgical site infection (SSI), in this paper we discuss the results of a randomized clinical trial which examined the type of sutures used during hepatectomy. METHODS: All hepatic resections performed from January 2007 to November 2008 at the Department of Surgery at Iizuka Hospital in Japan were included in this study. There were 125 patients randomly assigned to an absorbable sutures (Vicryl) gro...

Norifumi Harimoto; Ken Shirabe; Tomoyuki Abe; Takafumi Yukaya; Eiji Tsujita; Tomonobu Gion; Kiyoshi Kajiyama; Takashi Nagaie

2011-01-01

186

Percutaneous Mesh Expansion and Fixation at the Retro-Rectus Plane without Stabs by Using Redirecting Suture Hook in Midline Hernias Repair  

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Full Text Available Background: Mesh expansion and fixation at retro-rectus plane through multiples stabs produces good results. But these stabs cause cosmetic disorders for the patients and doctors. So, we find some modification to do this procedure without these stabbing wounds in midline hernial repair. Patients and methods: This technique was used to fix the mesh at retro-rectus plane in 50 patients suffering from midline hernias, from January 2008 through January 2010 at Zagazig university Hospital, Egypt. Laparotomy incision was done over the hernial sac or at old incision; the contents were then released and reduced into peritoneal cavity without much subcutaneous dissection. The suitable sheet of polypropylene mesh to cover the hernial defect and any weak area was prepared and fixed at retro-rectus plane percutaneously without stabbing wounds by using redirecting suture hook. The mean period of follow up was 26 months. Results: There was no recurrence during the period of follow up. Five patients developed subcutaneous bluish discoloration at the site of some stitches, which disappear within two weeks with conservative treatment. Conclusion: Percutaneous mesh expansion and fixation at retro-rectus plane by using redirecting suture hook procedure has good results in recurrence rate and cosmetic appearance.

Ayman F Mehanna

2011-06-01

187

Comparison of suture methods and materials in experimental inferior alveolar nerve grafting.  

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Currently, peripheral nerve defects are being treated successfully by microsurgical techniques using autogenous nerve transplantations and synthetic suture materials. This paper describes the influence of various suture methods and materials on nerve repair as experimentally evaluated in rabbits. The results show that the action potentials of the nerves anastomosed with polyglycolic acid sutures recovered faster than those anastomosed with nylon. PMID:6294261

Yamazaki, Y; Noma, H

1983-01-01

188

[Fascial closure of median laparotomies with a synthetic, resorbable suture material (polyglycolic acid)].  

Science.gov (United States)

In a prospective randomized study polyglycolic acid sutures (PGA) and polyester sutures for closure of median abdominal fascial incisions are compared. Occurrence of infection, incisional hernia, wound dehiscence and suture fistulas is evaluated. With regard to these complications no significant differences could be detected. PGA shows its advantage in less tissue reaction (avoiding fistulae). PMID:6274592

Ullrich, F; Henningsen, B; Böttcher, W

1981-12-01

189

Tensile strength of fascia lata sutures following gamma radiation.  

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Gamma radiation (Co-60) is used to sterilize biological sutures. We wished to compare the effect of gamma-radiation in doses of 2.7 and 4.0 Mrads on the tensile strength of human fascia lata sutures obtained from the same cadaver. Five variables of tensile strength viz. Breaking Elongation, Breaking Load, Yield Point Load, Work of Rupture and Elastic Stiffness were determined for each suture. For Breaking Elongation the mean strength for the 4.0 Mrad dose was 3% less than for 2.7 Mrad dose (P less than 0.05); for Breaking Load 11% less (P less than 0.01); for Yield Point Load 9% less (P less than 0.02); for Work of Rupture 14% less (P less than 0.01); and for Elastic Stiffness 8% less (P less than 0.02). Irradiation with 4.0 Mrads, does not greatly change the tensile strength characteristics of fascia lata sutures. PMID:890592

Cutz, A; Reid, D B; Basu, P K

1977-07-01

190

Angiogenesis and osteogenesis in an orthopedically expanded suture  

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The purpose of this study was to examine the angiogenic and the subsequent osteogenic responses during a 96-hour time-course after sutural expansion. Fifty rats were divided into: (1) a control group that received only angiogenic induction through injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) an experimental group that received orthopedic expansion and rhECGF; (3) a sham group that received expansion and sodium chloride (NaCl) injection; and (4) a baseline group that received no expansion or injection. All rats were injected with 3H-thymidine (1.0 microCi/gm) 1 hour before death to label the DNA of S-phase cells. Demineralized sections (4 microm thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration were analyzed with a previously established cell kinetics model. Analysis of variance was used to test the hypothesis that enhancement of angiogenesis stimulates reestablishment of osteogenic capability. Blood vessel number, area, and endothelial cell-labeled index significantly increased in experimental groups, but no difference was found between control and baseline groups. Labeled-pericyte index and activated pericyte numbers in the experimental group were also higher than in the sham groups. These results show that supplemental rhECGF enhances angiogenesis in expanded sutures but not in nonexpanded sutures. Data also suggest that pericytes are the source of osteoblasts in an orthopedically expanded suture.

Chang, H. N.; Garetto, L. P.; Potter, R. H.; Katona, T. R.; Lee, C. H.; Roberts, W. E.

1997-01-01

191

Healing of the suture line in the irradiated small intestine  

International Nuclear Information System (INIS)

With the help of data from literature the author goes more deeply into the aetiology, treatment and possible prevention of lesions of the small intestine related to preceding irradiation. In a clinical retrospective study at twenty patients who, after irradiation of the abdominal and pelvic areas, have been submitted to abdominal surgery, the relation is studied between predistion factors for gastrointestinal complications after irradiation, the surgeries applied in case of small-intestine problems and postoperative complications. The third part of the thesis covers an experimental part in which the healing process of suture line in the terminal ileum has been studied after resection and reanastomosis in previously irradiated bowel of the rat. It was investigated whether differences occurred in the healing process of suture line after various periods - 4, 10 and 40 weeks, after irradiation. Also comparison took place with a control group which underwent a similar procedure with the exception of the radiation treatment, which was simulated in this group. In a second experiment it was investigated if the healing process of suture line depends on the type of anastomosis. An end-to-end anastomosis was chosen versus side-to-side anastomosis. Also in this experiment an irradiated group was compared with a control group. Furthermore a method was developed for performing micro-angiographies of the rat intestine in order to demonstrate obliteration of blood vessels in irradiated intestine and to assess neovascularization in the intestinal wall at the suture line. (author). 84 refs.; 18 figs.; 27 tabs

192

Obliteration of serrated sutures of a human skull (review  

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Full Text Available The review presents information on obliteration of serrated sutures of a human skull. It considers the age-specific variability and sexual dimorphism. The causes of craniostenosis and dependence of cranial form on degree and type of craniostenosis are described

Zaichenko A.A.

2011-09-01

193

Suture supported P C IOL in a homocystinuric child.  

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Full Text Available A homocystinuric child presented with a secondary pupillary block glaucoma due to anteriorly subluxated lens. After removal of the subluxated lens, a suture supported posterior chamber IOL was implanted. Postoperative complication of cerebral venous thrombosis following general anaesthesia was managed with high doses of pyridoxine special diet and drugs.

Bhatti S

1996-01-01

194

Study on grafting acrylonitrile and acrylic acid onto polypropylene nonwoven fabrics polypropylene nonwoven fabrics  

International Nuclear Information System (INIS)

In this paper, co-grafting reaction of acrylonitrile and acrylic acid onto pre-irradiated polypropylene nonwoven fabrics in air medium has been studied. The degree of grafting has been determined as a function of irradiation dose, reaction temperature, reaction time, monomer concentration, ratio of monomers and the concentration of Mohr's. The results showed that the best condition of grafting reaction was reaction temperature 75 degree C, reaction time 4 h, monomer concentration 50%. Structure of the grafted polymer have been studied by FT-IR. (authors)

195

Unravelling the molecular control of calvarial suture fusion in children with craniosynostosis  

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Full Text Available Abstract Background Craniosynostosis, the premature fusion of calvarial sutures, is a common craniofacial abnormality. Causative mutations in more than 10 genes have been identified, involving fibroblast growth factor, transforming growth factor beta, and Eph/ephrin signalling pathways. Mutations affect each human calvarial suture (coronal, sagittal, metopic, and lambdoid differently, suggesting different gene expression patterns exist in each human suture. To better understand the molecular control of human suture morphogenesis we used microarray analysis to identify genes differentially expressed during suture fusion in children with craniosynostosis. Expression differences were also analysed between each unfused suture type, between sutures from syndromic and non-syndromic craniosynostosis patients, and between unfused sutures from individuals with and without craniosynostosis. Results We identified genes with increased expression in unfused sutures compared to fusing/fused sutures that may be pivotal to the maintenance of suture patency or in controlling early osteoblast differentiation (i.e. RBP4, GPC3, C1QTNF3, IL11RA, PTN, POSTN. In addition, we have identified genes with increased expression in fusing/fused suture tissue that we suggest could have a role in premature suture fusion (i.e. WIF1, ANXA3, CYFIP2. Proteins of two of these genes, glypican 3 and retinol binding protein 4, were investigated by immunohistochemistry and localised to the suture mesenchyme and osteogenic fronts of developing human calvaria, respectively, suggesting novel roles for these proteins in the maintenance of suture patency or in controlling early osteoblast differentiation. We show that there is limited difference in whole genome expression between sutures isolated from patients with syndromic and non-syndromic craniosynostosis and confirmed this by quantitative RT-PCR. Furthermore, distinct expression profiles for each unfused suture type were noted, with the metopic suture being most disparate. Finally, although calvarial bones are generally thought to grow without a cartilage precursor, we show histologically and by identification of cartilage-specific gene expression that cartilage may be involved in the morphogenesis of lambdoid and posterior sagittal sutures. Conclusion This study has provided further insight into the complex signalling network which controls human calvarial suture morphogenesis and craniosynostosis. Identified genes are candidates for targeted therapeutic development and to screen for craniosynostosis-causing mutations.

Morris C Phillip

2007-12-01

196

Polypropylene and silica short fibers composites  

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Full Text Available The mechanical properties of composites strongly depend on the type of filler-polymeric matrix interface. An interface characterized by a strong bond between the filler and the matrix generally results in better mechanical properties. In this work, polypropylene, PP, was used as polymeric matrix and silica short fibers, SF, which are amorphous biogenic silica, were employed as filler. In order to promote a better filler-matrix interfacial adhesion, these fibers were previously modified with vinyltrimethoxysilane. The composites were prepared by extrusion and injection molding processes and their mechanical properties were evaluated according to tensile testing, ASTM D 268, by means a fractional factorial design (25-1. The studied factors included fiber content in the matrix, fiber surface modification, injection flow and testing rate. The composite cryogenic fractured surfaces were investigated by field emission scanning electron microscopy, FESEM. The fiber modification promoted a better fiber-matrix interfacial adhesion, resulting in optimized mechanical properties in relation to the others. In this way, the fiber modification was the most important factor on the mechanical performance of the composites.

Mariana Gava Segatelli

2012-04-01

197

Chemical imaging of wood-polypropylene composites.  

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Recent investigations of wood plastic composites have revealed a detrimental effect of using lubricant systems in production. This includes nullifying part or all of the mechanical benefit of using a polar compatibilizer, maleic anhydride polypropylene (MAPP), in the composite formulation. This investigation utilizes lubricants labeled with deuterium in conjunction with Fourier transform infrared (FT-IR) spectroscopy to allow for the separation of individual lubricants from all other material constituents. All of the deuterium labeled lubricants, used without MAPP, revealed their expulsion from the wood interface during crystallization. MAPP coupling agent was found to exist near the wood, but it is unclear if any covalent bonding with the hydroxyl functionality on the wood surface occurred. The addition of zinc stearate lubricants appears to nullify the activity of the anhydride functionality near the wood surface as evidenced by a shift in the FT-IR spectra to the hydrolyzed form of the coupling agent. Most of the additives collect at the edges of the spherulites in mostly amorphous regions of the material. The consequence of this morphology may be a weak interface between crystallites. PMID:16925926

Harper, David P; Wolcott, Michael P

2006-08-01

198

Diffusion in Polypropylene Melts: Role of Stereochemistry.  

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We have performed numerical simulations and experiments at 180^oC to study the effect of stereochemical composition on the diffusion (D) of linear polypropylene melts of moderate polydispersity. The coarse-grained Monte-Carlo (MC) simulations were based on the rotational isomeric state model and repulsive Lennard-Jones potentials. For the pulsed-gradient ^1H NMR diffusion measurements the three specimens used had probabilities of meso diad Pm = 0.02, 0.23, and 0.89. The conversion factor between MC steps and real time was obtained by comparison with the measured D; no dependence on stereochemistry was evident. Using a molecular-weight (M)-scaling known from earlier work on n-alkanes, results were normalized to a common M after accounting for differences in experimental polydispersity. Results agreed closely with the monodisperse simulations. D at high Pm was found to be several times faster than at low Pm, but the simulation also showed a maximum in D at Pm near 0.75, an effect attributed to quenched randomness. Likely for similar reasons the experimental D-distribution for the Pm = 0.89 sample greatly exceeded that expected from the known polydispersity.

von Meerwall, Ernst; Waheed, Numan; Mattice, Wayne

2007-03-01

199

Polypropylene matrix composites reinforced with coconut fibers  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Polypropylene matrix composites reinforced with treated coconut fibers were produced. Fibers chemically treated (alkalization-CCUV samples) or mechanically treated (ultrasonic shockwave-CMUV samples) were dried using UV radiation. The goal was to combine low cost and eco-friendly treatments to impro [...] ve fiber-matrix adhesion. Composite samples containing up to 20 vol. (%) of untreated and treated coconut fibers were taken from boxes fabricated by injection molding. Water absorption and mechanical properties were investigated according to ASTM D570-98 and ASTM D638-03, respectively. Electrical characterizations were carried out to identify applications of these composites in the electrical sector. NBR 10296-Electrical Tracking Standard (specific to industry applications) and conductivity measurements were obtained applying 5 kV DC to the samples. CMUV samples containing 5 vol. (%) fiber presented superior tensile strength values (?~28 MPa) compared to the untreated fibers composite (?~22 MPa) or alkali treatment (?~24 MPa). However, CMUV composites containing 10 vol. (%) fiber presented best results for the electrical tracking test and electrical resistivity (3 × 10(7) ?.m). The results suggest that composites reinforced with mechanically treated coconut fibers are suitable for electrical applications.

Maria Virginia, Gelfuso; Pedro Vieira Gurgel da, Silva; Daniel, Thomazini.

2011-09-01

200

Surface modification of polypropylene based particle foams  

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This paper deals with the modification of the surface properties of expanded polypropylene (EPP). EPP is a semi-hard to soft elastic thermoplastic foam. The characteristic surface of EPP shows process-related steam nozzle imprints and gussets. Therefore EPP does not satisfy the quality requirements for visible automotive applications. In order to meet these demands, plastic surfaces are usually enhanced with functional or decorative coatings, e.g. textiles, plastic films or paint. The coating of plastics with low surface energies such as PP often leads to adhesion problems by reason of the missing polar and functional groups. This paper gives an evaluation of activation and pre-treatment methods of EPP, with the aim to identify the most suitable pre-treatment method. For this purpose five typical surface treatment methods - flame treatment, corona, fluorination, atmospheric and low-pressure plasma - were performed on EPP samples. As a comparison criterion the maximum increase in the adhesion force between a polyurethane-based coating and the modified EPP substrate was selected. Moreover the influence of the selected pre-treatment method on the increase in the total surface energy and its polar component was investigated by the drop shape analysis method. The results showed that the contact angle measurement is a suitable method to determine the polar and disperse fractions of the surface tension of EPP. Furthermore, all performed methods increased the adhesion of EPP.

Schreier, P.; Trassl, C.; Altstädt, V.

2014-05-01

 
 
 
 
201

Organoclay Networking in Polypropylene-Clay Nanocomposites  

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We report on networking of organoclays and its influence on the rheology of polypropylene-clay nanocomposites. Samples are blended using either a twin screw extruder (TSE) or a single screw extruder with in situ addition of supercritical CO2 (SCCO2). Blends contain proportional amounts (3:1) of maleic anhydride functionalized PP and organically modified montmorillonite (Cloisite^ 15A, Southern Clay Products) at several clay loadings in a base PP resin (MFI 12 g/10 min at 230 C). Small-amplitude oscillatory shear (SAOS) and steady shear flow were utilized to probe clay morphology with varying annealing time. In SAOS experiments repeated over several hours, the terminal behavior of the TSE samples became increasingly solid-like; in steady shear, the magnitude of the viscosity overshoot increased with annealing time. The single-screw/SCCO2 materials at the same clay loadings differed little rheologically from the neat resin. Finally, network formation kinetics accelerated with increasing temperature, and sufficiently large deformations irreversibly weakened the network structure.

Oberhauser, James; Treece, Mark

2006-03-01

202

Influence of Morphology on Electrical Properties of Syndiotactic Polypropylene Compared with Those of Isotactic Polypropylene  

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The influence of morphology on the electrical properties of syndiotactic polypropylene (sPP) has been investigated in comparison with those of conventional isotactic polypropylene (iPP). The evolution of spherulite in sPP occurred at a lower temperature than in iPP, and the size of spherulites in sPP is much smaller than those of iPP, though the number of spherulites increases drastically. The influence of heat treatment on the electrical properties of sPP, such as conductivity and current density-electric field characteristics, is negligible in contrast to iPP, in which the conductivity increased drastically and breakdown strength decreased markedly due to growth of large spherulites upon heat treatment. These results are discussed in terms of morphological change upon heat treatment. As a result, sPP is confirmed to be an excellent candidate for a new insulating polymer for cables which can be used at a much higher operating temperature than that of widely used cables with cross-linked polyethylene (XLPE) (90°C), because of its thermal stability, stable electrical properties even following heating treatment and mechanical flexibility due to the small spherulite size and low crystallinity under any preparation and treatment conditions.

Kim, Dong; Yoshino, Katsumi; Inoue, Takeo; Abe, Masaru; Uchikawa, Nobutaka

1999-06-01

203

Post irradiation degradation of polypropylene radiation durability of polypropylene stabilized with phenolic stabilizer (II)  

Energy Technology Data Exchange (ETDEWEB)

Post irradiation degradation of {sup 60}Co gamma irradiated polypropylene stabilized with a phenolic type stabilizer has been followed up to two years after being irradiated. The effectiveness of the stabilizer at various concentrations on the polypropylene samples irradiated up to 150 kGy has been studied and the buildup of carbonyl group in the irradiated samples measured. The obtained results indicated that the oxidative reactions are retarded by addition of stabilizer. The variation of bend strength of the irradiated samples with and without stabilizer was also followed. This property was found to be greatly improved for the stabilized samples irradiated at low doses. However at high doses the effectiveness of the stabilizer declined. In order to correlate these results with the change in the molecular weight of polymer, trends of the change in rheological behaviour such as melt viscosity ({mu}{sub a}) and flow behavior parameters (K, n) of both stabilized and unstabilized samples have been investigated. Results showed that at low doses, addition of the stabilizer greatly reduces the extent of chain scission, and therefore, the mechanical properties of the irradiated polymer are retained. (Author).

Yousefi, A. [Atomic Energy Organization of Iran, Tehran (Iran, Islamic Republic of). Gamma Irradiation Center; Katbab, A.A. [Amir Kabir Technical Univ., Teheran (Iran, Islamic Republic of). Dept. of Physics

1994-12-01

204

Post irradiation degradation of polypropylene radiation durability of polypropylene stabilized with phenolic stabilizer (II)  

International Nuclear Information System (INIS)

Post irradiation degradation of 60Co gamma irradiated polypropylene stabilized with a phenolic type stabilizer has been followed up to two years after being irradiated. The effectiveness of the stabilizer at various concentrations on the polypropylene samples irradiated up to 150 kGy has been studied and the buildup of carbonyl group in the irradiated samples measured. The obtained results indicated that the oxidative reactions are retarded by addition of stabilizer. The variation of bend strength of the irradiated samples with and without stabilizer was also followed. This property was found to be greatly improved for the stabilized samples irradiated at low doses. However at high doses the effectiveness of the stabilizer declined. In order to correlate these results with the change in the molecular weight of polymer, trends of the change in rheological behaviour such as melt viscosity (?a) and flow behavior parameters (K, n) of both stabilized and unstabilized samples have been investigated. Results showed that at low doses, addition of the stabilizer greatly reduces the extent of chain scission, and therefore, the mechanical properties of the irradiated polymer are retained. (Author)

205

Degradation study of polypropylene (PP) and bioriented polypropylene (BOPP) in the environment  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Polymers are vastly employed for numerous purposes in different industrial segments and generate soaring quantities of discarding in the environment. This research analyzed the degradability/biodegradability of polypropylene films (PP) and Bioriented polypropylene (BOPP) polymers after 11 months int [...] erred in the São Giácomo landfill in Caxias do Sul. Comparing the buried PP film to a sample of virgin PP, two peaks of degrading activity appeared at the TG curve as well as structure modification typified by occurrence of new absorption bands at FTIR, which can be credited to changes in crystallinity. Thermal analysis carried out on the buried PP and BOPP showed decreases in the percentage of crystallinity due to chain scission. The major reduction was observed in the PP, since its crystallinity is a consequence of polymerization instead of chain orientation processes, as in BOPP. Cracks and erosion of the polymer surface were detected in both PP and BOPP, indicating degrading processes by microorganisms.

Carina, Longo; Michele, Savaris; Mára, Zeni; Rosmary Nichele, Brandalise; Ana Maria Coulon, Grisa.

2011-12-01

206

Effect of wollastonite and talc on the micromechanisms of tensile deformation in polypropylene composites  

International Nuclear Information System (INIS)

The work presented here describes the effect of wollastonite and talc on the micromechanisms of surface deformation and subsequent propagation into the bulk of low and high crystallinity polypropylenes during tensile straining. The potential of high resolution electron microscopy is utilized to examine deformation processes, and develop deformation mechanism maps. While mineral-reinforced polypropylenes exhibited an increase in tensile modulus, yield strength remained unaffected. Crystallization behavior indicated that the reinforcement minerals increase the rate of nucleation with consequent increase in percentage of bulk crystallinity. The reinforcement of polypropylene with wollastonite or talc alters the primary micromechanism of deformation from deformation bands/crazing in neat polypropylenes to wedge/ridge tearing in mineral-reinforced low crystallinity polypropylene composites. However, wedges were absent in high crystallinity polypropylene composites. The final fracture in reinforced polypropylene occurs by a mixed mode consisting of fibrillation and brittle mode, while crazing-tearing and brittle deformation are fracture modes for neat polypropylenes

207

Barbed versus standard sutures for closure in total knee arthroplasty: a multicenter prospective randomized trial.  

Science.gov (United States)

Barbed suture has been associated with improved closure efficiency and safety in TKA in prior studies. We performed a multicenter randomized controlled trial to determine the efficiency and safety of this technology in TKA. We prospectively randomized 411 patients undergoing primary TKA to either barbed running (n=191) or knotted interrupted suture closure (n=203). Closure time was measured intra-operatively. Cost analysis was based on suture and OR time costs. Closure time was shorter with barbed suture (9.8 vs. 14.5 min, p<0.001). Total closure cost was less with barbed suture ($324 vs. $419, p<0.001). Early complications and outcomes were similar between groups. The use of barbed suture in TKA is associated with shorter closure time, lower cost and similar outcomes and complications when compared with standard sutures. PMID:24973931

Gililland, Jeremy M; Anderson, Lucas A; Barney, Jacob K; Ross, Hunter L; Pelt, Christopher E; Peters, Christopher L

2014-09-01

208

Co-60 gamma radiation assisted diffusion of iodine in polypropylene  

Energy Technology Data Exchange (ETDEWEB)

Thin films of polypropylene having dimensions 50 mm x 15 mm x 350 {mu}m were immersed in 1 N iodine solution and then irradiated with Co-60 gamma radiation for the periods of 48, 96 and 144 h at the doses varying from 14.4 to 43.2 kGy. The films were also kept immersed in iodine solution for similar periods but without irradiation. Furthermore, the films were also directly-irradiated with Co-60 gamma radiation for similar periods and doses. The radiation-iodinated, plain-iodinated and directly-irradiated samples were characterized by using various techniques such as weight gain EDS, SEM, FTIR, UV-visible spectroscopy, contact angle and XRD. Weight gain, EDS and SEM collectively reveal that gamma irradiation enhances iodine intake in polypropylene. FTIR, EDS and contact angle measurements indicate that presence of iodine during irradiation resists radiation induced carbonylation of polypropylene. FTIR also shows presence of HOI (Hypoiodous acid) species instead of expected C-I bonds. UV-visible analysis unambiguously shows that presence of iodine enhances radiation induced band gap reduction process of polypropylene. XRD indicates that iodine decreases the crystallinity of polypropylene.

Mathakari, N.L.; Bhoraskar, V.N. [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune, Maharashtra 411007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ernet.i [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune, Maharashtra 411007 (India)

2010-09-15

209

Co-60 gamma radiation assisted diffusion of iodine in polypropylene  

Science.gov (United States)

Thin films of polypropylene having dimensions 50 mm × 15 mm × 350 ?m were immersed in 1 N iodine solution and then irradiated with Co-60 gamma radiation for the periods of 48, 96 and 144 h at the doses varying from 14.4 to 43.2 kGy. The films were also kept immersed in iodine solution for similar periods but without irradiation. Furthermore, the films were also directly-irradiated with Co-60 gamma radiation for similar periods and doses. The radiation-iodinated, plain-iodinated and directly-irradiated samples were characterized by using various techniques such as weight gain EDS, SEM, FTIR, UV-visible spectroscopy, contact angle and XRD. Weight gain, EDS and SEM collectively reveal that gamma irradiation enhances iodine intake in polypropylene. FTIR, EDS and contact angle measurements indicate that presence of iodine during irradiation resists radiation induced carbonylation of polypropylene. FTIR also shows presence of HOI (Hypoiodous acid) species instead of expected C-I bonds. UV-visible analysis unambiguously shows that presence of iodine enhances radiation induced band gap reduction process of polypropylene. XRD indicates that iodine decreases the crystallinity of polypropylene.

Mathakari, N. L.; Bhoraskar, V. N.; Dhole, S. D.

2010-09-01

210

Comparison of life cycle assessment for different volume polypropylene jars  

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Full Text Available When deciding what packaging is the most appropriate for a product there are many factors to be considered. One of them is the impact of the packaging on environment. In this work, life cycle inventory and life cycle assessment of two different volume packagings were compared. The data were collected on the types and amounts of materials and energy consumption in the process of packaging and distribution of hand cream packed in polypropylene jars of 200 and 350 mL. Life cycle inventory (LCI and life cycle impact assessment (LCA were calculated. It was found that the total mass flow was higher for the jars of 350 mL. After analyzing individual flows, it was found that in both cycles (polypropylene jars of 200 and 350 mL,the consumption of fresh water was a dominant flow. This fresh water flow is mostly (95% consumed in the injection molding process of manufacturing jars from polypropylene granules. The LCA analysis showed no significant difference in global warming potential between different volume jars. The process that mostly affected global warming was the production of polypropylene jars from polypropylene granules by injection molding for both jar volumes. Judging by the global warming potential, there is no difference of the environmental impact between investigated jars, but considering the mass flow and water consumption, more environmental friendly were the 200 mL jars.

Krki? Nevena M.

2012-01-01

211

Molecular conformation of polypropylene in the molten and crystalline states  

International Nuclear Information System (INIS)

Small-angle neutron scattering studies have been made of molten and crystalline polypropylene by using samples containing small amounts of deuterated polypropylene in a protonated polypropylene matrix. The specimens were characterized by small- and wide-angle X-ray scattering to determine the d-spacing and the degree of crystallinity x and by gel permeation chromatography to determine molecular weights Msub(w) and molecular weight distributions. The degree of crystallinity was varied from 0.5 to 0.7, the d-spacing from 120A to 250A and the molecular weight from 34,000 to 1,540,000. Clustering effects were not observed. The radii of gyration (s2)sup(1/2)sub(w) of the tagged molecules varied approximately proportional to Msup(1/2)sub(w) and were almost independent of d and x. In the melt, similar values were obtained which are within experimental uncertainties equal to those in theta-solution. For (s2)sub(w) kappa2 much >1, the scattering law approaches a kappa-2 dependence. A chain molecule model for the crystalline state is introduced which takes into account experimental results concerning the morphology of the polypropylene specimens as well as conformational parameters of the polypropylene molecules. (author)

212

Production of high melt strength polypropylene by gamma irradiation  

International Nuclear Information System (INIS)

High melt strength polypropylene (HMS-PP) has been recently developed and introduced in the market by the major international producers of polypropylene. Therefore, BRASKEM, the leading Brazilian PP producer, together with EMBRARAD, the leading Brazilian gamma irradiator, and the IPEN (Institute of Nuclear Energy and Research) worked to develop a national technology for the production of HMS-PP. One of the effective approaches to improve melt strength and extensibility is to add chain branches onto polypropylene backbone using gamma radiation. Branching and grafting result from the radical combinations during irradiation process. Crosslinking and main chain scission in the polymer structure are also obtained during this process. In this work, gamma irradiation technique was used to induce chemical changes in commercial polypropylene with two different monomers, Tri-allyl-isocyanurate (TAIC) and Tri-methylolpropane-trimethacrylate (TMPTMA), with concentration ranging from 1.5 to 5.0 mmol/100 g of polypropylene. These samples were irradiated with a 60Co source at dose of 20 kGy. It used two different methods of HMS-PP processing. The crosslinking of modified polymers was studied by measuring gel content melt flow rate and rheological properties like melt strength and drawability. It was observed that the reaction method and the monomer type have influenced the properties. However, the concentration variation of monomer has no effectr has no effect

213

A Case of Intraluminal Endoscopic Suturing of Gastric Perforation  

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Full Text Available Recent endoscopic equipment development enabled to diagnose premalignant conditions and early gastric and colon cancer resulting in the rise of new methods of endoscopic treatment — endoscopic mucosal resection and endoscopic submucosal dissection. The advantages of such operation are obvious — minimal invasion, organ function preservation, a reduced hospitalization period, though these interventions carry the risk of iatrogenic complications (bleeding, perforation. Perforation is the most dangerous complication requiring immediate laparotomy. The authors have described a case of successful application of endoscopic suturing device to manage gastric wall iatrogenic perforation resulted from endoscopic submucosal dissection for submucous gastric tumor. The defect was closed using Apollo Overstitch endoscopic suturing device (USA avoiding laparotomy. The postoperative period was uneventful, and the patient was discharged 5 days after surgery.

S.V. Kantsevoy

2014-06-01

214

Local tissue reaction to implantation of biodegradable suture materials.  

Science.gov (United States)

Morphological changes in tissues adjacent to the implant were studied 1, 2, 6, and 12 months after implantation of biodegradable suture materials (catgut thread, DemeTECH polyfilament thread, and Surgilactin monofilament thread) into subcutaneous fat of rats. Tissue reaction to implantation of different suture materials developed as usual in response to a wound process and to a foreign body. By the end of month 1. the stage of traumatic perifocal inflammation was replaced in all groups by the proliferative phase with formation of new vessels and connective tissue. A trend to reduction of the productive inflammation activity from month 1 to month 12 was noted. Complete degeneration of the material after 12 months with complete recovery of the histoarchitecture of the adjacent tissues (restitution) was detected only after implantation of DemeTECH polyfilament thread. PMID:25065322

Kuznetsova, I V; Maiborodin, I V; Shevela, A I; Barannik, M I; Manaev, A A; Brombin, A I; Maiborodina, V I

2014-07-01

215

HUESOS SUTURALES EN EL PTERION SUTURAL BONES IN THE PTERION  

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Full Text Available Las variaciones de los huesos del cráneo son de interés para la anatomía, antropología física, imagenología y medicina legal. Con el propósito de aportar mayores detalles sobre los huesos suturales que se presentan en el pterion, fueron analizados 205 cráneos secos de individuos brasileños, adultos, de ambos sexos, blancos y no blancos. El hueso sutural fue observado en 31 cráneos (15,1%, localizándose 19 en el lado derecho (61,3%, 8 en el izquierdo (25,8% y 4 en ambos lados (12,9%. Con relación al sexo, 14 estuvieron presentes en cráneos masculinos (45,2% y 17 en femeninos (54,8%. En relación al grupo étnico, 20 eran del grupo blancos (64,5% y 11 de no blancos (35,5%. Las articulaciones de este hueso sutural con los huesos vecinos fueron clasificados en 4 tipos: Tipo I, donde se articuló con los huesos frontal, parietal, ala mayor del esfenoides y temporal, disposición encontrada en 17 cráneos (54,8%; Tipo II, donde se articuló con el parietal, temporal y ala mayor del esfenoides, encontrado en 11 cráneos (35,5%; Tipo III, donde se articuló con el temporal, frontal y ala mayor del esfenoides, observado en 2 cráneos (6,5 % y Tipo IV, donde se articuló con el parietal, frontal y ala mayor del esfenoides, encontrado en 1 cráneo (3,2%. Correlacionando las variables lado, sexo, grupo étnico y hueso sutural, el análisis estadístico reveló que la presencia de estos huesos es significativa en los individuos blancos y en el lado derechoCranium bones variations have been an object of interest for Anatomy, Physical Anthropology, X-Rays and Tomographic Images and Forensic Medicine. The aim of this article is to increase the knowledge of anatomical details about a sutural bone localized in the pterion. We observed 205 cranium of adult cadavers from Brazilian origin, of both sexs, white and non white ethnic group. The sutural bone was found in 31 cranium (15.1%, 19 in the right side (61.3%, 8 in the left side (25.5% and 4 in both sides (12.9%. In respect of the sex, 14 were observed in male cranium (45.2% and 17 in female cranium (54.8%. With respect to the ethnic group, 20 cases (64.5% corresponded to white individuals and 11 (35.5% to non white. Sutural bone joints with the next bones, were classified in four groups: Type I, the sutural bone joined with the frontal, parietal, greater wing of the sphenoid and temporal bones, this type was observed in 17 cranium (54.8%; Type II, it joined with the greater wing of the sphenoid, parietal and temporal bones, this type was observed in 11 cranium (35.5%; Type III, the sutural bone joined with the greater wing of the sphenoid, temporal and frontal bones, this type was observed in only 2 cranium (6.5% and Type IV, it joined with the greater wing of the sphenoid, parietal and frontal bones, this type was observed in only 1 cranium (3.2%. The statistical analysis of the different variables considered in this article showed that the presence of these bones is significative in white individuals and also in the right side in respect of all specimens

M. T. T. Braga

2000-01-01

216

HUESOS SUTURALES EN EL PTERION / SUTURAL BONES IN THE PTERION  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Las variaciones de los huesos del cráneo son de interés para la anatomía, antropología física, imagenología y medicina legal. Con el propósito de aportar mayores detalles sobre los huesos suturales que se presentan en el pterion, fueron analizados 205 cráneos secos de individuos brasileños, adultos, [...] de ambos sexos, blancos y no blancos. El hueso sutural fue observado en 31 cráneos (15,1%), localizándose 19 en el lado derecho (61,3%), 8 en el izquierdo (25,8%) y 4 en ambos lados (12,9%). Con relación al sexo, 14 estuvieron presentes en cráneos masculinos (45,2%) y 17 en femeninos (54,8%). En relación al grupo étnico, 20 eran del grupo blancos (64,5%) y 11 de no blancos (35,5%). Las articulaciones de este hueso sutural con los huesos vecinos fueron clasificados en 4 tipos: Tipo I, donde se articuló con los huesos frontal, parietal, ala mayor del esfenoides y temporal, disposición encontrada en 17 cráneos (54,8%); Tipo II, donde se articuló con el parietal, temporal y ala mayor del esfenoides, encontrado en 11 cráneos (35,5%); Tipo III, donde se articuló con el temporal, frontal y ala mayor del esfenoides, observado en 2 cráneos (6,5 %) y Tipo IV, donde se articuló con el parietal, frontal y ala mayor del esfenoides, encontrado en 1 cráneo (3,2%). Correlacionando las variables lado, sexo, grupo étnico y hueso sutural, el análisis estadístico reveló que la presencia de estos huesos es significativa en los individuos blancos y en el lado derecho Abstract in english Cranium bones variations have been an object of interest for Anatomy, Physical Anthropology, X-Rays and Tomographic Images and Forensic Medicine. The aim of this article is to increase the knowledge of anatomical details about a sutural bone localized in the pterion. We observed 205 cranium of adult [...] cadavers from Brazilian origin, of both sexs, white and non white ethnic group. The sutural bone was found in 31 cranium (15.1%), 19 in the right side (61.3%), 8 in the left side (25.5%) and 4 in both sides (12.9%). In respect of the sex, 14 were observed in male cranium (45.2%) and 17 in female cranium (54.8%). With respect to the ethnic group, 20 cases (64.5%) corresponded to white individuals and 11 (35.5%) to non white. Sutural bone joints with the next bones, were classified in four groups: Type I, the sutural bone joined with the frontal, parietal, greater wing of the sphenoid and temporal bones, this type was observed in 17 cranium (54.8%); Type II, it joined with the greater wing of the sphenoid, parietal and temporal bones, this type was observed in 11 cranium (35.5%); Type III, the sutural bone joined with the greater wing of the sphenoid, temporal and frontal bones, this type was observed in only 2 cranium (6.5%) and Type IV, it joined with the greater wing of the sphenoid, parietal and frontal bones, this type was observed in only 1 cranium (3.2%). The statistical analysis of the different variables considered in this article showed that the presence of these bones is significative in white individuals and also in the right side in respect of all specimens

M. T. T., Braga; C., Gabrielli; A, De Souza; C. F. S., Rodrigues; J. C., Marino.

217

Effect of concentration on ultrasonic degradation of chlorinated polypropylene  

International Nuclear Information System (INIS)

The molecular weights of chlorinated polypropylene in toluene solution at various concentrations were determined. Limiting molecular weight of polymers under ultrasonic irradiation could be obtained by the data fitting technique. The fitting accuracy of common kinetic equations for experimental data of chlorinated polypropylene was evaluated. It was found that the fitting results of these kinetic equations were not satisfactory. In order to fit the experimental data better, a new second order kinetic equation was proposed. This equation described well the experimental data. It was found that the fitting results for available experimental data of other polymers using this new equation were better than when using equations in the literature. Therefore, the equation proposed here is a new supplement to the original kinetic equations for polymers under ultrasonic irradiation. For chlorinated polypropylene, the rate of ultrasonic degradation decreased with increasing concentration while the limiting molecular weights increased with increasing concentration

218

Morphology and mechanical properties of polypropylene-wood flour composites  

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Full Text Available The microstructure and mechanical properties of polymer composites based on polypropylene and wood flour modified with monochloroacetic acid were investigated. Scanning electron microscopy and wide-angle X-ray diffraction were used as methods to probe the composite microstructures, while the tensile test was used to measure the physical strength. The wood flour modification was performed at different levels of monochloroacetic acid, ranging from 0.01 to 1 mol, while the modified wood flour was used as filler for polypropylene at 10, 20 and 30 wt.-%. It was found that increasing the monochloroacetic acid fraction influences the microstructure of the composites and leads to more homogeneous products. The introduction of non-modified wood flour decreases the polypropylene crystallization degree, but it improves after introduction of monochloroacetic acid. Physical-mechanical tests showed positive effects on tensile tests and Charpy notched impact strength. The new composites appear to be promising materials for construction purposes.

Vasileva, St.

2006-11-01

219

Development of a Constitutive Model of Polypropylene for Thermoforming  

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In this paper the authors outline a constitutive model, implemented within finite element analyses, which was developed for large deformation, high temperature multi-axial stretching of polypropylenes. The model has been generalised to a fully 3-dimensional thermally coupled form. The paper describes how model parameters were characterised using constant width, biaxial and sequential stretching of polypropylenes at elevated temperature using a custom built flexible biaxial stretching machine developed at Queen's University Belfast. The paper presents results of finite element model predictions of material stretching behaviour compared to range of physical experiments. The results presented in the paper confirm that this model is very effective in predicting the complex thermo-mechanical behaviours of polypropylenes at elevated temperatures.

O'Connor, C.; Martin, P.; Menary, G.; Sweeney, J.; Caton-Rose, P.; Spencer, P.

2011-05-01

220

Gamma radiation resistance of tale-polypropylene composite materials  

International Nuclear Information System (INIS)

Samples of isostatic polypropylene mixed with 10, 20 and 30 wt.% Talc were prepared. Sample films were gamma irradiated at 10 - 300 k Gy under air. The results from DSC suggested that fine particles of Talc showed pronounced nucleating effect by increasing the rate of crystallization and thermal stability. However, Talc-filled composites did not showed radiation resistant property. Absorbance intensity of carbonyl and hydroperoxide indicated the amount of oxidative degradation were increased with increasing radiation dose but would not depend on the Talc content. Talc was found to enhance polypropylene embrittlement and to lower the mechanical properties. However at appropriate concentration of Talc and low gamma dose. It is possible to improve the mechanical properties of the composites. In the field of environmental study, Talc-filled composites of iso tactic polypropylene may be used as a degradable plastic

 
 
 
 
221

Efficacy of b-lynch brace suture in postpartum haemorrhage  

International Nuclear Information System (INIS)

Massive uncontrolled haemorrhage after childbirth is the leading cause of maternal death in developing countries. Postpartum haemorrhage is traditionally defined as blood loss of more than 500 ml after vaginal delivery and more than 1000 ml after caesarean section, but intraoperative estimation of blood loss is inaccurate. Uterine atony alone accounts for 75 - 90% of PPH. To estimate the effectiveness and safety of B-Lynch brace Suture in the management of primary postpartum haemorrhage (PPH). (author)

222

Penile torsion correction by diagonal corporal plication sutures  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Penile torsion is commonly encountered. It can be caused by skin and dartos adherence or Buck’s fascia attachments. The authors suggest a new surgical approach to solve both problems. If Buck’s fascia involvement is demonstrated by artificial erection then a new diagonal corporal plication suture is [...] described to effectively solve this problem.

Brent W., Snow.

2009-02-01

223

Silicon oxide diffusion barrier coatings on polypropylene  

International Nuclear Information System (INIS)

In this study the influence of process conditions for the plasma-enhanced chemical vapor deposition of SiOx diffusion barrier coatings on polypropylene (PP) is investigated and compared to results obtained on polyethylene terephthalate (PET). It was observed that the thermal load during deposition is much more crucial in the case of PP. If the thermal load is not the limiting factor, the composite parameter (CP) energy input per mass of precursor showed to be valuable to describe plasma conditions at constant oxygen to monomer ratio. Low oxygen transmission rates (OTRs) of 5.1 ± 3.6 and 0.3 ± 0.1 cm3/m2day/atm were achieved on PP and PET foil, respectively, for an optimal CP of 4.1 x 105 J/g. Fourier transform infrared (FTIR) spectroscopy revealed that low carbon and silanol content is necessary for good barrier performance. Low RF power, necessary to reduce thermal load on PP, can be compensated by increasing the oxygen to monomer ratio. For favorable plasma conditions, the dependence of the OTR on the coating thickness follows a similar trend for both substrate materials with a critical thickness of approximately 12 nm. The residual permeation can be correlated to the defect density at each stage of film growth by means of a simple correlation. Further support for permeation through defects is found by the activated rate theory, since the apparent activation energy of oxygen permeation is below typical values of amorphous glasses and remains unchanged due to the deposition of SiOx on both substrates.

224

Morphology of drawn syndiotactic polypropylene films  

Science.gov (United States)

Morphological studies were conducted to investigate the drawability of melt-quenched (MQ) and slowly cooled (MSC) films of syndiotactic polypropylene (sPP) with a high syndiotactic pentad fraction. Transmission electron microscopy (TEM) using the ruthenium tetraoxide staining and ultrathin sectioning method revealed that amorphous chains as the matrix of MQ film played a role in drawability of the film by their alignment to machine direction (MD) and partial crystallizations into nanofibrils. On the other hand, the initial strain induced, rotations of clusters of long lamellar crystals as the major entity of MSC film accompanying breaks of long lamellae and formation of crazes and microvoids at the cluster boundary. Compared with a homogeneous thinning of MQ film by drawing, ca. 100 nm-thick layer slips along MD and parallel to the film surface took place in MSC film. This gave rise to the formation of V-shaped bent lamellar morphology and their further break into a smaller cluster of stacked lamellae which were aligned oblique by ca. 35° from MD. With elongation, some nanofibrils formed from chains generated by the partial breaks of lamellae are aligned perpendicular to the remained oblique lamellae and others parallel to MD in region where lamellar morphology almost disappeared. No chain slips in the nanofibrils can be related to a low elongation at break, i.e. a low ductility of sPP films. The lower elongation at break for MSC film than for MQ one can be interpreted by microvoids initially formed in the neck region and later moved to the fully drawn part, the microvoids initiating the break of the drawn film.

Harasawa, J.; Uehara, H.; Yamanobe, T.; Komoto, T.; Terano, M.

2002-06-01

225

Efeitos cardiovasculares e midriáticos da fenilefrina tópica a 2,5 e a 10,0% em voluntários sadios Cardiovascular and pupillary effects of topical ophthalmic 2.5 and 10.0% phenylephrine in healthy volunteers  

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Full Text Available OBJETIVO: Comparar os efeitos cardiovasculares e midriáticos da fenilefrina tópica nas concentrações de 2,5 e 10,0%. MÉTODOS: Ensaio clínico do tipo caso controle, randomizado, com auto-emparelhamento. Foram monitoradas a freqüência cardíaca (FC, a pressão arterial (PA e a midríase em voluntários sadios, com idade entre 18 e 45 anos, após a instilação da fenilefrina a 2,5 e a 10,0% em duas ocasiões diferentes. RESULTADOS: A amostra foi constituída de 28 voluntários, sendo 17 do sexo masculino e 11 do sexo feminino, com a idade média de 26,5 anos. Não foi verificado nenhum padrão de mudanças com relação à freqüência cardíaca e à pressão arterial sistólica. Com relação à pressão arterial diastólica média dos indivíduos, não foi encontrada variação significativa após a instilação da fenilefrina a 2,5% nos tempos de um, cinco, dez e 30 minutos, o que se revelou bem diferente quando do uso da fenilefrina a 10,0%, com a qual houve aumento da pressão arterial diastólica média após cinco e dez minutos, e subseqüente queda após 30 minutos, porém sem significância estatística. A midríase foi maior com a fenilefrina a 10,0% nos dois olhos, sendo a diferença estatisticamente significativa. CONCLUSÕES: Observou-se maior efeito midriático da fenilefrina a 10,0%, quando comparada a 2,5%, com significância estatística. Já com relação aos efeitos cardiovasculares não houve diferença estatística entre as duas concentrações.PURPOSE: To compare the cardiovascular and mydriatic effects of 2.5% and 10.0% phenylephrine. METHODS: A case-control, randomized, crossover clinical trial study. We monitored heart rate (HR, blood pressure (BP and mydriasis in healthy volunteers aged 18-45 years after the instillation of 2.5% and 10.0% phenylephrine in two different occasions. RESULTS: The sample comprised 28 healthy volunteers, 17 male and 11 female, with a mean age of 26.5 years. No changes in heart rate and systolic blood pressure were observed. No significant variation of the mean diastolic blood pressure was found after 1, 5, 10 and 30- minute instillation of 2.5% phenylephrine. However, with 10.0% phenylephrine, there was an increase in mean diastolic blood pressure after five and ten minutes, followed by a drop after 30 minutes, which was not statistically significant. Mydriasis was more marked in both eyes with a statistically significant difference after instillation of 10.0% phenylephrine. CONCLUSIONS: The mydriatic effect was greater with 10.0% phenylephrine than with 2.5% phenylephrine and the difference was statistically significant. No statistically significant difference was found in relation to cardiovascular effects in both phenylephrine concentrations.

Alberto Diniz Filho

2007-12-01

226

Arthroscopic Suture Bridge Fixation of Tibial Intercondylar Eminence Fractures  

Science.gov (United States)

Tibial intercondylar eminence fractures that are displaced and non-reducible require open or arthroscopically assisted repair. Ideally, fracture reduction and fixation would be performed with a technique that has low morbidity, allows easy visualization and reduction, provides firm fixation, does not violate the proximal tibial physis, avoids metal hardware, and does not require a second procedure for implant removal. The suture bridge technique, used in the shoulder for rotator cuff tears and greater tuberosity fracture repair, has the ability to produce high contact pressures with rigid fixation. We describe an all-inside and all-epiphyseal arthroscopic suture bridge technique for tibial intercondylar eminence fracture repair performed with PushLock anchors (Arthrex, Naples, FL). One or 2 anchors preloaded with No. 2 FiberWire (Arthrex) are placed in the posterior fracture bed, followed by fracture reduction. The suture limbs are shuttled through and around the anterior cruciate ligament and over the fracture fragment in crossing fashion and are secured by use of additional anchors placed at the anteromedial and anterolateral fracture margin. The anchors are placed obliquely to avoid the proximal tibial physis in the pediatric population. Anatomic reduction and secure fixation allow more aggressive rehabilitation and faster restoration of joint function. PMID:24400173

Sawyer, Gregory A.; Hulstyn, Michael J.; Anderson, Brett C.; Schiller, Jonathan

2013-01-01

227

Modified technique for arthroscopic Bankart repair using anchor sutures.  

Science.gov (United States)

Bankart repair, or one of its modifications, is currently the gold standard procedure for treatment of anterior traumatic shoulder instability. It is now possible to perform the operation arthroscopically with the introduction of suture anchors. As described by Eugene Wolf, arthroscopic shoulder stabilization using the Mitek (Mitek Surgical Products, Ethicon, Edinburgh, U.K.) anchors requires two anterior portals and intra-articular knot tying. However, sliding the anchor on the inside limb of a suture loop could be challenging because the other limb could get tangled in the nitinol arc of the anchor. We describe a modification of the original technique to prevent that possibility and avoid any tension on the repair tissue during anchor passage. The proposed modification involves the use of a cheap, readily available silastic feeding tube to isolate the outside limb of the suture loop and stabilize labral tissues while the anchor is being passed. This tube also serves as a stent for knot tying. By allowing the whole operation to be performed through one anterior portal, the modified technique reduces possible morbidity associated with a second portal and further reduces cost. PMID:15243444

Saweeres, Emad S B; Thomas, Andrew P

2004-07-01

228

Polypropylene—Polyethylene Melts: Phase Structure Determination by Rheology  

Science.gov (United States)

Using dynamic moduli and transmission electron microscopy images the phase structure of polypropylene-polyethylene melts was studied. Blends consisting of 80% base material (polypropylene-homopolymer or ethylene-propylene copolymer) and of 20% modifier polymer (a C2/C8-elastomer, a linear low density polyethylene or a high density polyethylene) forming a two-phase structure in the melt were investigated. The influence of the viscosity ratio and the interfacial tension on the particle size of the inclusions was investigated. Both factors can be determined from dynamic moduli by using the emulsion model of Palierne [1] to calculate the interfacial tension.

Kock, Cornelia; Schausberger, A.; Aust, N.; Gahleitner, M.; Ingolic, E.

2008-07-01

229

Synthesis and Modification of Polypropylene by Radiation-induced Grafting  

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Full Text Available Polypropylene fiber (PP was radiation-induced graft polymerization of lauryl acrylate (LA and butyl acrylate (BAusing a 60Co gamma radiation source. Then the grafted polypropylene fiber was characterized by a Fourier transforminfrared (FT-IR spectrometer, Scanning Electron Microscopy (SEM, differential scanning calorimetry (DSC andthermogravimetry (TG, which indicated that LA and BA have been grafted onto PP. The article focused on somefactors that influenced on the graft degree, such as the cross-linking agent concentration, monomer concentration. Theresults showed that: the degree of grafting BA reached the maximum of 20.53%, while the maximum graft degree of LAwas 29.90%.

Feng Yuan

2009-02-01

230

Preparation of organophilic clays and polypropylene nano composites  

International Nuclear Information System (INIS)

Polypropylene/montmorillonite nano composites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organo clay. The modified clays with the quaternary ammonium salts were introduced in a polypropylene matrix with 3 wt. % of clay. The interlayer distance (d001) of the clay particles were obtained by X- ray diffraction and the thermal stability of the systems were investigated by thermogravimetry. The organo clay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. (author)

231

Investigation of Mechanical Properties of Rice Straw Fibre Polypropylene Composites  

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Full Text Available The main objective of present work is to investigate the mechanical properties of rice straw fibre reinforced polypropylene composites at different weight fractions (0%, 5%, 10%, 15%, 20% and 25% of rice straw fibre. Rice straw fibre reinforced polypropylene composites were manufactured according to ASTM standards using injection moulding technique. The developed composites were then tested for their tensile, bending and impact properties. The standard test methods ASTM-D638M for tensile properties, ASTM-D790M for flexural properties and ASTM-D256M for impact properties of rice straw fibre composites, were used.

K Sudhakar,

2014-01-01

232

Anomalous behavior of secondary dielectric relaxation in polypropylene glycols  

International Nuclear Information System (INIS)

A surprising slow down in the dielectric secondary ?-relaxation with temperature increasing near the glass transition is confirmed for several polypropylene glycols. The peculiar behavior diminishes as the molecular weight grows. The minimal model (Dyre and Olsen 2003 Phys. Rev. Lett. 91 155703) is applied successfully to describe the temperature dependences of the ?-relaxation times. The minimal model parameters are analyzed for different molecular weights. A molecular explanation of the ?-process anomaly for polypropylene glycols is proposed on the basis of the minimal model prediction

233

Influence of different types of surgical suture materials on mehanical damage of oral mucosa  

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Full Text Available Introduction. Throughout history many kinds of different suture materials have been used for closing and suturing surgical wounds. Medical literature describes four basic characteristics of suture material: knot safety, tensile strength, tissue reaction and wound safety. The tissue reaction is reflected in an inflammatory response, which, though minimal, occurs during first two to seven days after implanting suture into the tissue. The aim of this research was to investigate whether different suture materials affect the development of decubital damage of oral mucosa, which to a great extent can compromise the process of wound healing. Material and methods. The investigation was designed as a prospective clinical study including 150 patients of both genders, aged between 25 and 60. The patients were distributed into three groups of 50 persons. The suture Black Silk was used in the first group, designated as a control group. Nylon and Vicril were used in the second and third group, i.e. experimental groups, respectively. Decubital damage of the surrounding soft tissues was the main parameter for monitoring the effects of selected suture materials on the oral mucosa. Conclusion. The comparison of results obtained for the investigated suture materials after suturing oral mucosa revealed that certain advan­tage could be given to synthetic monofilament suture materials

Mirkovi? Siniša

2011-01-01

234

Bending and abrasion fatigue of common suture materials used in arthroscopic and open orthopedic surgery.  

Science.gov (United States)

In orthopedic surgery, the reattachment of tendon to bone requires suture materials that have stable and durable properties to allow time for healing at the tendon-bone interface. The suture, not rigidly restrained within the anchor eyelet, is free to move during surgery and potentially after surgery with limb motion. During such movement, the suture is subjected to bending and frictional forces that can lead to fatigue-induced failure. We investigated some common contemporary commercial number-two-grade suture materials and evaluated their resistance to bending abrasion fatigue and the consequent failure. Sutures were oscillated over a stainless steel wire at low frequency under load. Number of abrasion cycles to failure, changes in suture morphology, and fatigue-failure method was recorded for each material. Suture structure had a significant effect on abrasion resistance, with braided sutures containing large numbers of fine high tenacity core filaments performing 15-20 times better than other braided suture structures. Ultra high molecular weight polyethylene (UHMWPE) core filaments resisted bending abrasion failure better than other core materials due to the load spreading and abrasion resistance of these filaments. Sutures with UHMWPE cores also had high resistance to tensile failure. Limited correlation was observed between tensile strength and abrasion resistance. PMID:22777625

Savage, Earle; Hurren, Christopher J; Slader, Simon; Khan, Lukman A K; Sutti, Alessandra; Page, Richard S

2013-01-01

235

Ultrastructure, Histochemistry, and Mineralization Patterns in the Ecdysial Suture of the Blue Crab, Callinectes sapidus  

Science.gov (United States)

The ecdysial suture is the region of the arthropod exoskeleton that splits to allow the animal to emerge during ecdysis. We examined the morphology and composition of the intermolt and premolt suture of the blue crab using light microscopy and scanning electron microscopy. The suture could not be identified by routine histological techniques; however 3 of 22 fluorescein isothiocyanate-labeled lectins tested (Lens culinaris agglutinin, Vicia faba agglutinin, and Pisum sativum agglutinin) differentiated the suture, binding more intensely to the suture exocuticle and less intensely to the suture endocuticle. Back-scattered electron (BSE) and secondary electron observations of fracture surfaces of intermolt cuticle showed less mineralized regions in the wedge-shaped suture as did BSE analysis of premolt and intermolt resin-embedded cuticle. The prism regions of the suture exocuticle were not calcified. X-ray microanalysis of both the endocuticle and exocuticle demonstrated that the suture was less calcified than the surrounding cuticle with significantly lower magnesium and phosphorus concentrations, potentially making its mineral more soluble. The presence or absence of a glycoprotein in the organic matrix, the extent and composition of the mineral deposited, and the thickness of the cuticle all likely contribute to the suture being removed by molting fluid, thereby ensuring successful ecdysis.

Priester, Carolina; Dillaman, Richard M.; Gay, D. Mark

2005-12-01

236

Absorbable and nonabsorbable sutures in microsurgery: standardized comparable studies in rats.  

Science.gov (United States)

In order to study the applicability and value of synthetic absorbable suture materials in microvascular surgery, 8-0 monofilament nonabsorbable polyamide sutures and 8-0 absorbable polyglycolic acid and polyglactin 910 sutures were used in end-to-end anastomoses of the aorta in rats, employing the same microsurgical model for all procedures. Comparable investigations of the anastomotic sites were carded out macroscopically and histologically at various intervals postoperatively. It was found that when placed under unphysiologic strain, microvascular anastomoses sutured with absorbable materials had less mechanical endurance than anastomoses stitched with nonabsorbable suture materials. It was also found, however, that this had no significance in vivo, inasmuch as no vascular ruptures or aneurysms appeared with either the absorbable or nonabsorbable sutures even after long-term observation. The nonabsorbable sutures were fully recognizable up to 150 days, microscopically showing clear evidence of granuloma formation. The absorbable sutures, on the other hand, could hardly be discerned after 50 days, and after 150 days the foreign body and scar reactions had almost completely disappeared. Absorbable suture materials lead to more rapid restitution of the vascular wall than nonabsorbable sutures and consequently appear to be superior. PMID:16317948

Thiede, A; Lütjohann, K; Beck, C; Blunck, F

1979-01-01

237

Análise das aderências resultantes da fixação de telas cirúrgicas com selantes de fibrina e sutura: modelo experimental intraperitoneal / Analysis of adhesions resulted from mesh fixation with fibrin sealant and suture: experimental intraperitoneal model  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Comparar fixação cirúrgica de telas de polipropileno (PP) e telas de polipropileno revestido (PCD), usando fio de sutura de polipropileno e cola biológica, quanto à formação de aderências intraperitoneais. MÉTODOS: Amostra de 46 ratas Wistar, randomizadas em seis grupos: dois grupos-contro [...] le, com cinco ratas cada, que foram submetidos um à incisão medial (IM) e o outro à uma incisão em forma de U (IU); nenhum desses grupos recebeu tela. Dois grupos com tela de PP, um com dez ratas, fixada com sutura (PPF), e o outro, com seis ratas, fixada com cola biológica (PPC). E Dois grupos com tela de PCD, no primeiro, com dez animais, a tela foi fixada com sutura (PCDF), e no segundo, com dez animais, com cola biológica (PCDC). RESULTADOS: Após o prazo de 21 dias, os grupos-controle não apresentaram aderências significantes. O grupo PPC apresentou menor grau de aderência do que o grupo PPF (p=0,01). Não houve diferença entre as fixações nos grupos com PCD. CONCLUSÃO: A comparação da fixação apresentou diferença estatística significativa apenas à tela de PP, com menor grau de aderência utilizando a cola. As aderências se localizaram predominantemente nas extremidades das telas estudadas. Abstract in english OBJECTIVE: To compare surgical fixation of polypropylene mesh (PP) and coated polypropylene mesh (PCD) using polypropylene suture and fibrin glue, as for the formation of intraperitoneal adhesions. METHODS: A sample of 46 female Wistar rats were randomized into six groups: two control groups, with f [...] ive rats each, were subjected to one medial incision (MI) and the other to a U-shaped incision (UI), none of these groups received the mesh. Two groups of PP mesh, with ten rats, fixed with suture (PPF), the other with six rats, fixed with biological glue (PPC). And two groups of PCD mesh, at first, with ten animals, the mesh was fixed with sutures (PCDFs) and the second with ten animals with biological glue (PCDC). RESULTS: After 21 days, the control groups showed no significant adhesions. The PPC group showed a lower degree of adhesion than the PPF group (p = 0.01). There was no difference between the groups with PCD. CONCLUSION: Comparison of fixation was statistically different only with PP mesh, with lesser degrees of adherence when using the glue. Adhesions were predominantly located at the extremities of the meshes studied.

Juliano Hermes Maeso, Montes; André Vicente, Bigolin; Renata, Baú; Roberto, Nicola; João Vicente Machado, Grossi; Cláudia Juliana, Loureiro; Leandro Totti, Cavazzola.

238

Análise das aderências resultantes da fixação de telas cirúrgicas com selantes de fibrina e sutura: modelo experimental intraperitoneal Analysis of adhesions resulted from mesh fixation with fibrin sealant and suture: experimental intraperitoneal model  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Comparar fixação cirúrgica de telas de polipropileno (PP e telas de polipropileno revestido (PCD, usando fio de sutura de polipropileno e cola biológica, quanto à formação de aderências intraperitoneais. MÉTODOS: Amostra de 46 ratas Wistar, randomizadas em seis grupos: dois grupos-controle, com cinco ratas cada, que foram submetidos um à incisão medial (IM e o outro à uma incisão em forma de U (IU; nenhum desses grupos recebeu tela. Dois grupos com tela de PP, um com dez ratas, fixada com sutura (PPF, e o outro, com seis ratas, fixada com cola biológica (PPC. E Dois grupos com tela de PCD, no primeiro, com dez animais, a tela foi fixada com sutura (PCDF, e no segundo, com dez animais, com cola biológica (PCDC. RESULTADOS: Após o prazo de 21 dias, os grupos-controle não apresentaram aderências significantes. O grupo PPC apresentou menor grau de aderência do que o grupo PPF (p=0,01. Não houve diferença entre as fixações nos grupos com PCD. CONCLUSÃO: A comparação da fixação apresentou diferença estatística significativa apenas à tela de PP, com menor grau de aderência utilizando a cola. As aderências se localizaram predominantemente nas extremidades das telas estudadas.OBJECTIVE: To compare surgical fixation of polypropylene mesh (PP and coated polypropylene mesh (PCD using polypropylene suture and fibrin glue, as for the formation of intraperitoneal adhesions. METHODS: A sample of 46 female Wistar rats were randomized into six groups: two control groups, with five rats each, were subjected to one medial incision (MI and the other to a U-shaped incision (UI, none of these groups received the mesh. Two groups of PP mesh, with ten rats, fixed with suture (PPF, the other with six rats, fixed with biological glue (PPC. And two groups of PCD mesh, at first, with ten animals, the mesh was fixed with sutures (PCDFs and the second with ten animals with biological glue (PCDC. RESULTS: After 21 days, the control groups showed no significant adhesions. The PPC group showed a lower degree of adhesion than the PPF group (p = 0.01. There was no difference between the groups with PCD. CONCLUSION: Comparison of fixation was statistically different only with PP mesh, with lesser degrees of adherence when using the glue. Adhesions were predominantly located at the extremities of the meshes studied.

Juliano Hermes Maeso Montes

2012-12-01

239

Síntese da parede abdominal: avaliação de dois tipos de sutura contínua em ratos / Abdominal wall syntheses: comparison between two types of continuous suture  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Comparar a sutura simples contínua e a sutura contínua em oito vertical no fechamento da parede abdominal de ratos. MÉTODOS: Quarenta e oito ratos machos Wistar, foram submetidos a laparotomia padronizada e fechamento da parede abdominal com sutura simples contínua (n=24) e sutura contínua [...] em oito-vertical (n=24), com fio de polipropileno. No 7° e 14° pós-operatório foram submetidos a eutanásia 12 animais de cada grupo e deles retirados a camada músculo-aponevrótica da parede abdominal envolvendo a cicatriz operatória e preparados para exames histológico e imunohistoquímico. Os segmentos levados ao exame histológico foram corados por Hematoxilina-eosina sendo feita observação qualitativa do processo cicatricial e Picrosirius red F3BA, para avaliação quantitativa do colágeno. Também foram estudadas as porcentagens de macrófagos na linha de sutura por imunohistoquímica. Para a quantificação de macrófagos e fibras colágenas foi utilizado avaliação histológica por digitalização de imagem, baseados nos princípios de espectrofotometria. Os dados encontrados foram analisados estatisticamente pelos testes qui-quadrado, exato de Fisher e Mann-Whitney (p Abstract in english PURPOSE: To establish morphologic relationship between the continuous "simple mass" suture and the continuous far-near, near-far mass suture of longitudinal midline abdominal incision. METHODS: A total of 48 male Wistar rats underwent longitudinal standard laparotomy with equal distribution to one o [...] f two groups: GI- continuous "simple mass" suture, GII-continuous far-near, near-far suture, both with polypropylene. On postoperative day 7th or14th, 12 animals of each group were submitted to euthanasia and anterior abdominal wall was removed (without skin) for histologic and immune- histochemistry analysis. The samples of the abdominal wall were stained by hematoxylin-eosin in order to performed a qualitative healing tissue reaction. Others samples were stained by Picrosirius red F3BA in order to performed a quantitative analysis of macrophages and collagen. Statistical analysis was done by use the chi-square test, Fisher exact test and Mann-Whitney variance test ( p

Vanessa Medeiros, Loureiro; Djalma José, Fagundes; Murched Omar, Taha.

240

Síntese da parede abdominal: avaliação de dois tipos de sutura contínua em ratos Abdominal wall syntheses: comparison between two types of continuous suture  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Comparar a sutura simples contínua e a sutura contínua em oito vertical no fechamento da parede abdominal de ratos. MÉTODOS: Quarenta e oito ratos machos Wistar, foram submetidos a laparotomia padronizada e fechamento da parede abdominal com sutura simples contínua (n=24 e sutura contínua em oito-vertical (n=24, com fio de polipropileno. No 7° e 14° pós-operatório foram submetidos a eutanásia 12 animais de cada grupo e deles retirados a camada músculo-aponevrótica da parede abdominal envolvendo a cicatriz operatória e preparados para exames histológico e imunohistoquímico. Os segmentos levados ao exame histológico foram corados por Hematoxilina-eosina sendo feita observação qualitativa do processo cicatricial e Picrosirius red F3BA, para avaliação quantitativa do colágeno. Também foram estudadas as porcentagens de macrófagos na linha de sutura por imunohistoquímica. Para a quantificação de macrófagos e fibras colágenas foi utilizado avaliação histológica por digitalização de imagem, baseados nos princípios de espectrofotometria. Os dados encontrados foram analisados estatisticamente pelos testes qui-quadrado, exato de Fisher e Mann-Whitney (pPURPOSE: To establish morphologic relationship between the continuous "simple mass" suture and the continuous far-near, near-far mass suture of longitudinal midline abdominal incision. METHODS: A total of 48 male Wistar rats underwent longitudinal standard laparotomy with equal distribution to one of two groups: GI- continuous "simple mass" suture, GII-continuous far-near, near-far suture, both with polypropylene. On postoperative day 7th or14th, 12 animals of each group were submitted to euthanasia and anterior abdominal wall was removed (without skin for histologic and immune- histochemistry analysis. The samples of the abdominal wall were stained by hematoxylin-eosin in order to performed a qualitative healing tissue reaction. Others samples were stained by Picrosirius red F3BA in order to performed a quantitative analysis of macrophages and collagen. Statistical analysis was done by use the chi-square test, Fisher exact test and Mann-Whitney variance test ( p< 0,05. RESULTS: The findings of the macrophages cells and the collagen evaluation were statistical significantly on day 7th. CONCLUSION:The continuous far-near, near-far technique improved the abdominal wall healing on day 7th. On day 14th the findings were the same.

Vanessa Medeiros Loureiro

2003-06-01

 
 
 
 
241

Near-surface deformation in polypropylene blends  

Science.gov (United States)

Polypropylene blends with up to 20% rubber phase are known as thermoplastic polyolefin or TPO and have been widely used in the automotive industry in both painted and unpainted components. Poor scratch resistance and paint adhesion have been of great concern for TPO applications. The research described in this thesis has addressed both of these issues by studying the near-surface deformation under scratches in unpainted TPO, and the interfacial adhesion and deformation of painted TPO. A transmission electron microscopy approach has been developed to study the microstructure and microdeformation in this important class of engineering materials. It was observed that highly oriented near-surface material in injection-molded TPO plastically deformed by forming periodic shear bands under scratches. The material inside the shear band dilated as revealed by the difference in the angles between the shear band boundary and the rubber particles inside and outside the shear bands. The extent of material dilation inside the shear bands decreased with the distance from the free surface and increased with normal applied load. At high applied normal loads (>400 g), a significant amount of voiding caused by the debonding between the rubber phase and the PP matrix was observed. Talc particles were found to preferentially wet the rubber phase and this may prevent debonding between talc particles and the PP matrix as observed in talc-filled pure PP. The anisotropy in scratching behavior correlates with the anisotropy in mechanical properties. The morphology of the scratching deformation was found to be particularly sensitive to the near-surface structural anisotropy. A tensile cracking test was applied to quantitatively measure the interfacial adhesion between paint and TPO substrates. Interfacial structure between chlorinated polyolefin adhesion promoter and TPO substrate was studied by electron microscopy. The swelling of the rubber phase near the interface was observed, evidently arising from the interaction with the solvent in the paint and adhesion promoter. Diffusion of the rubber phase near the interface was also observed. Baking at high temperature enhanced both the swelling and interfacial diffusion of rubber phase. Paint adhesion was improved in TPO substrates with lower molecular weight PP homopolymer, which was ascribed to the enhanced interfacial diffusion.

Tang, Honxiang

242

Effect of hot drawing process on physical and thermal properties of polypropylene fiber containing selective peroxide and comparison with conventional polypropylene fibers  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this research, the effect of the drawing process on the physical and thermal properties of commercially available polypropylene fiber containing selective peroxide was studied. Attempts have also been made to compare this drawn fiber sample with conventional polypropylene fibers produced from rea [...] ctor and with controlled rheology grades. The results showed that the drawn PP/Peroxide fiber has higher birefringence, tenacity, and initial modulus compared with that of the drawn polypropylene fiber. Moreover, the fraction of load carrying chains in various drawn polypropylene fibers was evaluated on the basis of simplified models.

Bahareh, Kalantari; Mohammad R. M., Mojtahedi; Ahmad M., Shoushtari; Aminoddin, Haji.

243

Effect of hot drawing process on physical and thermal properties of polypropylene fiber containing selective peroxide and comparison with conventional polypropylene fibers  

Directory of Open Access Journals (Sweden)

Full Text Available In this research, the effect of the drawing process on the physical and thermal properties of commercially available polypropylene fiber containing selective peroxide was studied. Attempts have also been made to compare this drawn fiber sample with conventional polypropylene fibers produced from reactor and with controlled rheology grades. The results showed that the drawn PP/Peroxide fiber has higher birefringence, tenacity, and initial modulus compared with that of the drawn polypropylene fiber. Moreover, the fraction of load carrying chains in various drawn polypropylene fibers was evaluated on the basis of simplified models.

Bahareh Kalantari

2012-01-01

244

Orientation of late Precambrian sutures in the Arabian-Nubian shield  

Science.gov (United States)

Recent tectonic models have resulted in conflicting descriptions of how the late Precambrian sutures of the Arabian-Nubian shield extend into northeast Africa. The Hamisana shear zone in northeastern Sudan is critical to this discussion because it truncates and disrupts two sutures, the Allaqi-Heiani and the Onib-Sol Hamed. Analysis of field structural data, Thematic Mapper imagery, and Rb-Sr and U-Pb geochronology suggests that the Allaqi-Heiani suture is the western extension of the Onib-Sol Hamed suture and that both make up the exposed parts of a far-traveled, polydeformed ophiolitic nappe complex. Subsequent deformation localized in the Hamisana shear zone disrupted this nappe and displaced the suture between 660 and 550 Ma during regional deformation associated with the Najd fault system. These results indicate that at least one suture extends westward into the interior of northern Africa.

Stern, Robert J.; Nielsen, Kent C.; Best, Eric; Sultan, Mohamed; Arvidson, Raymond E.

1990-01-01

245

Use of synthetic absorbable sutures for abdominal and chest wound closure. Experience with 650 consecutive cases.  

Science.gov (United States)

The advent of synthetic collagen suture (polyglycolic acid and polyglacin 910) has provided a new dimension in surgical suturing. However, surgeons in general have not yet taken full advantage of the potential that this new material offers. Associated evisceration and wound dehiscence rates as well as the incidence rate of wound infection were assessed since these represent standards by which the suture material can be evaluated. In an entire series of 650 cases, there has been one case of wound dehiscence with evisceration. The incidence of infection has been less than 1%, which is comparable to previous experience with interrupted, nonabsorbable sutures. The time required for closure using the new material has been approximately one third of that associated with the use of conventional interrupted closure sutures. This implies a substantial cost reduction for the patient. As a result of this experience, the synthetic absorbable sutures seem to represent the material of choice for routine abdominal or chest wound closure. PMID:346006

Murray, D H; Blaisdell, F W

1978-04-01

246

Broad-line NMR study of hot drawn polypropylene fibres  

International Nuclear Information System (INIS)

The influence of polypropylene fiber hot drawing on molecular mobility of polymer chains has been investigated by line broadening NMR method. Measurements have been done in the temperature range (200-420 K) where ?-relaxation processes in non crystalline regions are dominant and deformation are mostly probable

247

Broad-line NMR study of hot drawn polypropylene fibres  

Energy Technology Data Exchange (ETDEWEB)

The influence of polypropylene fiber hot drawing on molecular mobility of polymer chains has been investigated by line broadening NMR method. Measurements have been done in the temperature range (200-420 K) where {beta}-relaxation processes in non crystalline regions are dominant and deformation are mostly probable. 10 refs, 3 figs, 1 tab.

Mucha, L.; Murin, J.; Sevcovic, L. [Dept. of Physics, Technical Univ., Kosice (Slovakia)

1994-12-31

248

CRUDE PALM OIL AS A BIOADDITIVE IN POLYPROPYLENE BLOWN FILMS  

Directory of Open Access Journals (Sweden)

Full Text Available Growing public concern about environment and potential risks to health in the polymer and plasticizer industry promises to increase the market for a safer alternative plasticizer such as a vegetable oil-based agent. The purpose of this study was to investigate the potential of crude palm oil as a bio-additive in polypropylene blown films. The polypropylene was blended with 1%, 3%, and 5% dosages of CPO using a twin screw extruder. The extruded samples were blown using the blown thin film technique. Mechanical, physical, and morphological properties were characterized. Modifying polypropylene with CPO showed good enhancement in the mechanical properties of the polypropylene. Tensile strength, elongation at break, impact strength, and tear strength all increased. The scanning electron microscopy photographs of the CPO-modified PP clearly supported the results from the mechanical strength tests. The presence of CPO in the PP matrices decreased the density and increased the melt flow rate. These findings contribute new knowledge to the additives area and give important implications for designing and manufacturing polymer packaging materials.

Emiliana Rose Jusoh,

2012-01-01

249

Solution and Melt Rheology of Polypropylene Comb and Star Polymers  

Science.gov (United States)

Syndiotactic polypropylene macromonomer arms have been prepared by coordination-insertion polymerization. These arms have been made into polypropylene star polymers by the homopolymerization of the syndiotactic arms with a living alkene polymerization catalyst. The macromonomer arms have also been randomly copolymerized with propylene using rac-dimethylsilyl(2-methyl-4-phenylindenyl) zirconium dichloride catalysts to make polypropylene combs. Consequently we have star polymers and a series of comb polymers with different backbone lengths that are all made from the same macromonomer arms. We compare linear viscoelastic data on star and comb polypropylene melts and solutions in squalane to predictions of the tube dilation model and the tube model without tube dilation. The ratio of comb terminal relaxation time to star terminal relaxation time eliminates the friction coefficient and allows determination of the extent of tube dilation the backbone experiences when it relaxes. The concentration dependence of the comb/star terminal relaxation time ratio can be described by either model, owing to adjustable parameters that are not known apriori, so independent means to evaluate those parameters will be discussed.

Ghosh, Arnav; Colby, Ralph H.; Rose, Jeffrey M.; Cherian, Anna E.; Coates, Geoffrey W.

2006-03-01

250

Nanogels and microgels of polypropylene obtained by gamma irradiation  

International Nuclear Information System (INIS)

In preparation of HMS-PP (polypropylene modified by gamma irradiation), we use the iPP (isotactic polypropylene) in pellets, which was packaged in plastic container an then irradiated with 60Co gamma source containing acetylene pressure of 110 kPa and at doses of 5, 12.5 and 20 kGy. The gel fraction of the samples was determined by extraction of soluble components in boiling xylene for 12 hours at 138 deg C. The soluble portion of the sample was decanted with the total volatilization of xylene at room temperature (25 deg C) and deposited on glass slides. These samples were characterized by: scanning electron microscopy, scanning electron microscope with field emission. In this study the morphology, we obtained the formation of microgels with a higher incidence of polypropylene in PP 12.5 kGy and 20 kGy. Also it was found nanoscale structures of gels of polypropylene (nanogels) in samples of PP 12.5 kGy. (author)

251

Colorimetry analysis of polypropylene-polyethylene base copoliners  

International Nuclear Information System (INIS)

In this paper, crystallisation process study has been performed, from the molten material, in polypropylene-polyethylene (PP-PE) copolymers rich in PP (? 95 wgh.%), using different additives. Some samples have been artificially aged. Calorimetric analysis has been performed by different scanning calorimetry (DSC), from which crystallisation kinetics has been studied under dynamic conditions. (Author) 22 refs

252

Unidirectional barbed suture versus standard monofilament for urethrovesical anastomosis during robotic assisted laparoscopic radical prostatectomy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

PURPOSE: V-LocTM180 (Covidien Healthcare, Mansfield, MA) is a new unidirectional barbed suture that may reduce loss of tension during a running closure. We evaluated the use of the barbed suture for urethrovesical anastomosis (UVA) during robotic assisted laparoscopic prostatectomy (RALP). Time to completion of UVA, post-operative anastomotic leak rate, and urinary incontinence were compared in patients undergoing UVA with 3-0 unidirectional-barbed suture vs. 3-0 MonocrylTM (Ethicon, Somervil...

Marc Manganiello; Patrick Kenney; David Canes; Andrea Sorcini; Alireza Moinzadeh

2012-01-01

253

Complications of suture ligation ablation for ulnar polydactyly: a report of two cases  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report two cases resulting in complications following suture ligation treatment for ulnar polydactyly. One case consisted of bilateral, retained gangrene and cellulitis, and a second case consisted of a residual, sensitive skin tag. The case involving gangrene and cellulitis developed after an unsuccessful suture ligation of bilateral pedunculated duplicated digits. The second case developed after suture ligature ablation of a rudimentary digit in the nursery but presented 3 years later w...

Patillo, Dominic; Rayan, Ghazi M.

2011-01-01

254

Evaluation of surgical implantation of electronic tags in European eel and effects of different suture materials  

DEFF Research Database (Denmark)

Effects of implanting data-storage tags in European eel, Anguilla anguilla, and the suitability of different suture materials (braided permanent silk, permanent monofilament, absorbable and absorbable antibacterial) were examined. The tags consisted of an electronic unit and three floats on a wire, making them flexible and able to follow the swimming movements of the eel. No mortality occurred, and tagged fish did not differ from the control fish in growth. Sutures were shed or dissolved slowly. After 4 weeks, there was no difference among the groups in the proportion of sutures left. After 6 months, fish with braided silk had largely shed their sutures, fish with monofilament sutures had the majority of sutures left, whereas the fish with absorbable sutures were intermediate in between. Fish with monofilament sutures showed the least-extensive inflammation reactions and fastest wound healing. Antibacterial treatment had no effect on inflammation or healing rates. After 6 months, the tag started to become expelled through the incision in five fish (12%). The internal reaction appeared stronger around the floats, suggesting that the coating material of the floats created a tissue reaction, which should be further investigated. Intraperitoneal implantation appears to be a suitable tagging method for European silver eel, and it is recommended to close incisions using permanent monofilament sutures

Aarestrup, Kim

2013-01-01

255

A study of the efficacy of antibacterial sutures for surgical site infection: a retrospective controlled trial.  

Science.gov (United States)

To reduce bacterial adherence to surgical sutures, triclosan-coated polyglactin 910 suture materials with antiseptic activity were developed. The aim of this study was to evaluate whether the incidence of surgical site infections can be reduced when triclosan-coated sutures are used. Until December 2009, we used conventional polyglactin 910 sutures (VICRYL, Ethicon) for the closure of the fascia in digestive tract surgery. Therefore, for the control group we retrospectively collected surveillance data for 1.5 years. In the control group, 611 patients underwent digestive tract surgery with VICRYL sutures. Beginning in July 2010, we used triclosan-coated polyglactin 910 sutures (VICRYL Plus, Ethicon, Tokyo, Japan) for the closure of the fascia in all digestive surgeries. So, we collected data for the study group from July 2010 until June 2011. In the study group, 467 patients underwent digestive tract surgery with triclosan-coated VICRYL Plus sutures. In the control group, 75 patients (12.2%) developed wound infections. In the study group, 31 patients (6.6%) developed wound infections, which was significantly lower. Emergency cases; laparoscopic cases, including some cholecystectomy and colectomy cases; American Society of Anesthesiologists classification; the use of immunosuppressive therapy; colostomy cases; wound classification; and suture material were identified as the risk factors for wound infections. In both groups, as the wound classification worsened, the wound infection rate increased. Triclosan-coated polyglactin 910 antimicrobial sutures lead to a significant decrease in the incidence of surgical site infections, especially in clean/contaminated cases. PMID:23701147

Hoshino, Seiichiro; Yoshida, Yoichiro; Tanimura, Syu; Yamauchi, Yasushi; Noritomi, Tomoaki; Yamashita, Yuichi

2013-01-01

256

Comparative analysis of cranial suture complexity in the genus Caiman (Crocodylia, alligatoridae  

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Full Text Available The variation in degrees of interdigitation (complexity in cranial sutures among species of Caiman in different skull regions was studied by fractal analysis. Our findings show that there is a small species effect in the fractal dimension of cranial sutures, but most variation is accounted for by regional differentiation within the skull. There is also a significant interaction between species and cranial regions. The braincase sutures show higher fractal dimension than the facial skull sutures for all three species. The fractal dimension of nasal-maxilla suture is larger in Caiman latirostris than in the other species. The braincase sutures show higher fractal dimensions in C. sclerops than in the other species. The results suggest that different regions of the skull in caimans are under differential functional stress and the braincase sutures must counteract stronger disarticulation forces than the facial sutures. The larger fractal dimension shown by C. latirostris in facial sutures has probably a functional basis also. Caiman latirostris is known to have preferences for harder food items than the other species.

MONTEIRO L. R.

2000-01-01

257

Extrusion of bone anchor suture following flexor digitorum profundus tendon avulsion injury repair.  

LENUS (Irish Health Repository)

Flexor digitorum profundus (FDP) zone I tendon avulsion injury is traditionally repaired with a pullout suture technique. More recently, bone anchor sutures have been used as a viable alternative and have largely replaced areas in hand surgery where pullout suture technique was once required. To date, there have been very few complications reported related to bone anchor suture use in FDP tendon reattachment to the bone. We report a very unusual case of extrusion of bone anchor through the nailbed, 6 years after zone I FDP tendon avulsion injury repair and a brief review of literature.

Tiong, William H C

2011-09-01

258

Molecular basis of cranial suture biology and disease: Osteoblastic and osteoclastic perspectives  

Science.gov (United States)

The normal growth and development of the skull is a tightly regulated process that occurs along the osteogenic interfaces of the cranial sutures. Here, the borders of the calvarial bones and neighboring tissues above and below, function as a complex. Through coordinated remodeling efforts of bone deposition and resorption, the cranial sutures maintain a state of patency from infancy through early adulthood as the skull continues to grow and accommodate the developing brain's demands for expansion. However, when this delicate balance is disturbed, a number of pathologic conditions ensue; and if left uncorrected, may result in visual and neurocognitive impairments. A prime example includes craniosynostosis, or premature fusion of one or more cranial and/or facial suture(s). At the present time, the only therapeutic measure for craniosynostosis is surgical correction by cranial vault reconstruction. However, elegant studies performed over the past decade have identified several genes critical for the maintenance of suture patency and induction of suture fusion. Such deeper understandings of the pathogenesis and molecular mechanisms that regulate suture biology may provide necessary insights toward the development of non-surgical therapeutic alternatives for patients with cranial suture defects. In this review, we discuss the intricate cellular and molecular interplay that exists within the suture among its three major components: dura mater, osteoblastic related molecular pathways and osteoclastic related molecular pathways.

Beederman, Maureen; Farina, Evan M.; Reid, Russell R.

2014-01-01

259

A Comparative In Vivo Study of Tissue Reactions to Four Suturing Materials  

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Full Text Available INTRODUCTION: The purpose of this study was to compare the histopathologic reaction of four suturing materials: silk, polyvinylidene fluoride (PVDF, polyglycolic acid, and catgut in the oral mucosa of albino rabbits. MATERIALS AND METHODS: The twenty-one male mature albino rabbits which were used in this study were randomly divided into three groups of seven each. Silk, PVDF, polyglycolic acid and catgut suture materials were tested in the oral mucosa of these animals. The animals were sacrificed 2, 4, and 7 days after suturing. Two pathologists evaluated the samples by determining the presence and level of inflammation, granulation tissue, and fibrosis formation. Data were statistically analyzed by Kruskal Wallis and Mann-Whitney U tests. RESULTS: Histological features of the samples showed that PVDF and plain catgut suture materials produced more fibrous tissue (favorable response on the fourth day in comparison with silk suture (P=0.02. Also, in the 7-day samples PVDF sutures produced the mildest inflammation when compared with the silk sutures (P=0.015. CONCLUSION: According to the results of this study, it can be convey that PVDF suture materials created mild tissue reactions and can be a reasonable candidate for suturing oral tissues.

Shahla Kakoei

2010-06-01

260

Efeitos cardiovasculares e midriáticos da fenilefrina tópica a 2,5 e a 10,0% em voluntários sadios / Cardiovascular and pupillary effects of topical ophthalmic 2.5 and 10.0% phenylephrine in healthy volunteers  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Comparar os efeitos cardiovasculares e midriáticos da fenilefrina tópica nas concentrações de 2,5 e 10,0%. MÉTODOS: Ensaio clínico do tipo caso controle, randomizado, com auto-emparelhamento. Foram monitoradas a freqüência cardíaca (FC), a pressão arterial (PA) e a midríase em voluntários [...] sadios, com idade entre 18 e 45 anos, após a instilação da fenilefrina a 2,5 e a 10,0% em duas ocasiões diferentes. RESULTADOS: A amostra foi constituída de 28 voluntários, sendo 17 do sexo masculino e 11 do sexo feminino, com a idade média de 26,5 anos. Não foi verificado nenhum padrão de mudanças com relação à freqüência cardíaca e à pressão arterial sistólica. Com relação à pressão arterial diastólica média dos indivíduos, não foi encontrada variação significativa após a instilação da fenilefrina a 2,5% nos tempos de um, cinco, dez e 30 minutos, o que se revelou bem diferente quando do uso da fenilefrina a 10,0%, com a qual houve aumento da pressão arterial diastólica média após cinco e dez minutos, e subseqüente queda após 30 minutos, porém sem significância estatística. A midríase foi maior com a fenilefrina a 10,0% nos dois olhos, sendo a diferença estatisticamente significativa. CONCLUSÕES: Observou-se maior efeito midriático da fenilefrina a 10,0%, quando comparada a 2,5%, com significância estatística. Já com relação aos efeitos cardiovasculares não houve diferença estatística entre as duas concentrações. Abstract in english PURPOSE: To compare the cardiovascular and mydriatic effects of 2.5% and 10.0% phenylephrine. METHODS: A case-control, randomized, crossover clinical trial study. We monitored heart rate (HR), blood pressure (BP) and mydriasis in healthy volunteers aged 18-45 years after the instillation of 2.5% and [...] 10.0% phenylephrine in two different occasions. RESULTS: The sample comprised 28 healthy volunteers, 17 male and 11 female, with a mean age of 26.5 years. No changes in heart rate and systolic blood pressure were observed. No significant variation of the mean diastolic blood pressure was found after 1, 5, 10 and 30- minute instillation of 2.5% phenylephrine. However, with 10.0% phenylephrine, there was an increase in mean diastolic blood pressure after five and ten minutes, followed by a drop after 30 minutes, which was not statistically significant. Mydriasis was more marked in both eyes with a statistically significant difference after instillation of 10.0% phenylephrine. CONCLUSIONS: The mydriatic effect was greater with 10.0% phenylephrine than with 2.5% phenylephrine and the difference was statistically significant. No statistically significant difference was found in relation to cardiovascular effects in both phenylephrine concentrations.

Alberto, Diniz Filho; Maria, Frasson; Rafael Vidal, Mérula; Patrick Reis, Morais; Sebastião, Cronemberger.

 
 
 
 
261

Effectivity of intraoperative adjustable suture technique in horizontal strabismus  

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AIM To compare the long-term effectivity of intraoperative adjustable suture technique with traditional non-adjustable strabismus surgery. METHODS Two hundred and thirty-three patients, who underwent strabismus surgery either with traditional procedures or one-stage intraoperative adjustable suture technique, were included in our long-term follow-up study. One hundred and eighteen patients were evaluated in traditional surgery group (TSG) and 115 who underwent adjustable suture were in the one-stage intraoperative adjustable surgery group (ASG). In this group 9 patients had paralytic strabismus and 16 had reoperations, 2 patients had restrictive strabismus related to thyroid eye disease. The mean follow up in the TSG was 26.2 months and it was 24.8 months in the ASG group. RESULTS In patients with exotropia (XT) the mean correction of deviation for near fixation in ASG (32.4±13.2PD) and in TSG (26.4±8.2PD) were similar (P=0.112). The correction for distant fixation in ASG (33.2±11.4PD) and TSG (30.9±7.2PD) were not significantly different (P=0.321). In patients with esotropia (ET) even the mean correction of deviation for both near (31±12PD) and distant (30.6±12.8PD) fixations were higher in ASG than in TSG, for both near (28.27±14.2PD) and distant (28.9±12.9PD) fixations, the differences were not significant (P=0.346, 0.824 respectively). The overall success rate of XT patient was 78.9% in TSG and 78.78% in ASG, the difference was not significant (P=0.629). The success rates were 78.75% in TSG and 75.51% in ASG in ET patient, which was also not significantly different (P=0.821). CONCLUSION Although patients in ASG had more complex deviation such as paralysis, reoperations and restrictive strabismus, success rates of this tecnique was as high as TSG which did not contain complicated deviation. One-stage intraoperative adjustable suture technique is a safe and effective method for cooperative patient who has complex deviation. PMID:23991385

Altintas, Ayse Gul Kocak; Arifoglu, Hasan Basri; Midillioglu, Inci Kocak; Gungor, Elif Damar; Simsek, Saban

2013-01-01

262

Bone suture in management of mandibular degloving injury.  

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Traumatic degloving injuries of the mandible are rare intraoral soft tissue traumas. A simple review of the medical literature shows that no article up to this date has reported the prevalence of the degloving injuries of the mandible. Moreover, the highest incidence of mandibular degloving injuries is reported in children and young adults. In this article, the author describes the mandibular degloving injury, characterized by the separation of periosteum and soft tissues of the anterior buccal side of the mandible, and the bone suture technique. This article outlines that a correct diagnostic assessment and appropriate treatment plan can reduce the complications after mandibular degloving injuries. PMID:24470849

Rahpeyma, Amin; Khajeahmadi, Saeedeh

2013-01-01

263

Development of foams from linear polypropylene (PP) and high melt strength polypropylene (HMSPP) polymeric blends  

International Nuclear Information System (INIS)

Foamed polymers are future materials, with a comprehensive application field. They can be used in order to improve appearance of insulation structures, for example, or to reduce costs involving materials. This work address to Isotactic Polypropylene / High Melt Strength Polypropylene blends, for foams production. Rheological behavior of polymer melt, especially referring to viscosity in processing temperature, plays a decisive role in applications where dominates extensional flow, as in case of foaming. If the viscosity is very low, it will correspond to a low melt strength, as in case of linear homopolymer (Isotact PP), and the foam will be prejudiced, due to the impossibility of expansion. Otherwise, if the viscosity is very high, with a high melt strength, the foam will collapse immediately after its formation. In order to get foams with an homogeneous and defined cellular structure, there were accomplished blends, 50% in weight, between linear homopolymer (isotactic PP) and HMSPP, from PP modified as per gamma radiation, in acetylene environment and at a 12.5 kGy doses. Extrusion process used a soluble foaming methodology, according to a processing/dissolution principle, which involves the dissolution of a Physical Blowing Agent (PBA), under 30 bar pressure, homogeneously mixed with polymeric melt. Extrusion conditions, that generally involve temperature, pressure and viscoelastic material flow control were experimentally investigated to define prevalent characteristics for producing foams. Nitrogen was the used PBA and process extrusion parameters were adapted to PP, HMSPP and their 50% in weight mixtures thereof. Major PP and HMSPP characteristics were obtained via melt Index and melt strength and thermal analyses (DSC/TGA), in order to make viable and to reproduce foaming as per extrusion process. Foams cellular morphology of PP, HMSPP and their 50% in weight mixtures thereof was investigated, with and without talc addition, as nucleating agent, by using Scanning Electron Microscope (SEM). Micrographs obtained pointed to closed cells foams, in which the pressure is kept during all cell formation stage, informing that closed cells foams are used in thermal insulation in Civil Construction and in thermal vials. Density analyses accomplished in foams produced in our work showed typical results for high density foams (320 to 800 kg/m3 range), around 500 kg/m3, used for wire and cables and for structural purposes (structural foams), by replacing wood, metals or solid plastics. Structural foams have high density (above 320 kg/m3) and cellular structures are specially composed by holes. (author)

264

Reducing the number of sutures for vesicourethral anastomosis in radical retropubic prostatectomy  

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Full Text Available OBJECTIVE: To prospectively evaluate the outcome of using a two-suture technique for the vesicourethral anastomosis (VUA during radical retropubic prostatectomy (RRP. MATERIAL AND METHODS: Two groups of 50 patients each underwent nerve-sparing RRP for localized prostate cancer by one surgeon. In one group, the vesicourethral anastomosis was performed using 2 Vicryl 2-0 stitches placed at the 3- and 9-o’clock positions and in the other group 6 Vicryl 2-0 stitches were placed at the 2-, 4-, 6-, 8-, 10- and 12-o’clock positions. The intraoperative and perioperative parameters analyzed were time to perform the VUA, time to remove the drain and hospitalization. The rate of incontinence, anastomotic stricture and erectile function were included in the outcome analysis. RESULTS: The anastomotic time differed statistically between the 2 groups (mean 3.3 minutes for the 2-suture group and 10.5 minutes for the 6-suture group, p < 0.0001 with similar periods of drain removal (mean 3.12 days for the 2-suture group and 3.45 days for the 6-suture group; p = 0.13 and hospitalization (mean 4.66 days for the 2-suture group and 5.3 days for the 6-suture group; p = 0.09. The functional outcome was excellent for the 2-suture group with no patient suffering from incontinence or anastomotic strictures 1 year postoperatively, while in the 6-suture group there were 2 patients (4% suffering from incontinence (2 underwent sling procedure and 1 patient suffered from anastomotic stricture. CONCLUSION: The low number of sutures in the 2-suture VUA technique reduces operating times, does not influence perioperative and intraoperative parameters and results in excellent functional outcome.

Evangelos M. Mazaris

2009-04-01

265

[Primary strength of conventional and alternative suture techniques of the rotator cuff. A biomechanical study].  

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The aim of this biomechanical study was to evaluate rotator cuff repair strength using different suture anchor techniques compared to conventional repair, taking into consideration the native strength of the supraspinatus tendon. Therefore, a defined defect of the supraspinatus was created in 50 freshly frozen cadaver specimen (group size n = 10; median age at death: 56 years). Five methods were employed for cuff repair: standard transosseous suture, modified transosseous suture with patch augmentation and three suture anchors (Acufex Wedge TAG, Acufex Rod TAG und Mitek GII). The maximum tensile load of the five techniques was: standard transosseous suture, 410 N; modified transosseous suture, 552 N; Wedge TAG, 207 N; Rod TAG, 217 N; Mitek GII, 186 N. The difference between the suture anchor and standard techniques were highly significant (P Mitek Gll anchor showed the lowest anchor dislocation rate at 3% (n = 1). The Wedge TAG system had a dislocation rate of 27% (n = 8) and the Rod TAG system 43% (n = 13). Suture anchor techniques revealed about 20%, the standard technique 34% and its modification 60% of the hypothetically calculated native tendon strength. Compared to conventional transosseous suture techniques, the use of the suture anchors tested in this series does not significantly increase the primary fixation strength of rotator cuff repair. The metallic implant with two barbs (Mitek GII) seems to be superior to the polyacetal anchors when inserted into the spongiform bone of the greater tubercle. The considerably weaker repair strength needs to be taken into consideration in postoperative patient rehabilitation, especially after the use of suture anchors. PMID:11968555

Rickert, M; Witzel, U; Kölbel, R; Georgousis, H

2002-01-01

266

An experimental model to retraining in microvascular suture  

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Full Text Available SciELO Brazil | Language: English Abstract in english PURPOSE: To demonstrate an experimental model of up to four hours a week of independent study that allows relearning in microvascular sutures. METHODS: Wistar rats between 200 and 500 grams surplus research experiments were used. Femoral vessels are covered on one or both sides through a groin i [...] ncision obliquely along the inguinal ligament. Femoral artery and vein are isolated and measured being clamped and cut. The individual performs in microvascular anastomosis complexity arterial and venous terminoterminal sequence. terminolateral and venous and arterial grafts in vessels. Permeability is evaluated by testing vascular patency after creation of microvascular anastomosis. RESULTS: In the first specimen, only arterial and venous vascular anastomosis are performed terminoterminal. The average diameter of the femoral veins varies from 0.8 to 2 mm between rodents (artery, between 0.6 and 1.4 mm, between 0.8 and 2 mm vein). The superficiality of the vessels allows faster dissection, may also be held in other inguinal region. CONCLUSION: The model of individual retraining allows learning microvascular suture in individuals of permanent staff.

Marcos Ricardo de Oliveira, Jaeger; Pedro Bins, Ely; Jefferson André, Pires; Lydia Masako, Ferreira.

267

Assessing suturing techniques using a virtual reality surgical simulator.  

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Advantages of virtual-reality simulators surgical skill assessment and training include more training time, no risk to patient, repeatable difficulty level, reliable feedback, without the resource demands, and ethical issues of animal-based training. We tested this for a key subtask and showed a strong link between skill in the simulator and in reality. Suturing performance was assessed for four groups of participants, including experienced surgeons and naive subjects, on a custom-made virtual-reality simulator. Each subject tried the experiment 30 times using five different types of needles to perform a standardized suture placement task. Traditional metrics of performance as well as new metrics enabled by our system were proposed, and the data indicate difference between trained and untrained performance. In all traditional parameters such as time, number of attempts, and motion quantity, the medical surgeons outperformed the other three groups, though differences were not significant. However, motion smoothness, penetration and exit angles, tear size areas, and orientation change were statistically significant in the trained group when compared with untrained group. This suggests that these parameters can be used in virtual microsurgery training. PMID:20201052

Kazemi, Hamed; Rappel, James K; Poston, Timothy; Hai Lim, Beng; Burdet, Etienne; Leong Teo, Chee

2010-09-01

268

Polypropylene/calcium carbonate nanocomposites – effects of processing techniques and maleated polypropylene compatibiliser  

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Full Text Available The mechanical properties and crystalline characteristics of polypropylene (PP and nano precipitated calcium carbonate (NPCC nanocomposites prepared via melt mixing in an internal mixer and melt extrusion in a twin screw extruder, were compared. The effect of maleic anhydride grafted PP (PP-g-MAH as a compatibiliser was also studied using the internal mixer. At low filler concentration of 5 wt%, impact strength was better for the nanocomposites produced using the internal mixer. At higher filler loading of more than 10 wt%, the extrusion technique was more effective to disperse the nanofillers resulting in better impact properties. The impact results are consistent with the observations made from Scanning Electron Microscope (SEM morphology study. As expected, the flexural modulus of the nanocomposites increased with filler concentration regardless of the techniques utilised. At a same filler loading, there was also no significant difference in the moduli for the two techniques. The tensile strength of the mixed nanocomposites were found to be inferior to the extruded nanocomposites. Introduction of PP-g-MAH improved the impact strength, tensile strength and modulus of the mixed nanocomposites. The improvements may be attributed to better interfacial adhesion, as evident from the SEM micrographs which displayed better dispersion of the NPCC in the presence of the compatibiliser. Though NPCC particles have weak nucleating effect on the crystallization of the PP, addition of PP-g-MAH into the mixed nanocomposites has induced significant crystallization of the PP.

2010-10-01

269

Evaluation of polypropylene/saw dust composites prepared with maleated polypropylene (mapp) produced by reactive extrusion  

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Full Text Available SciELO Brazil | Language: English Abstract in english Considering the importance of the environment and fuel economy, the Brazilian automotive industry has focused on the development of lightweight materials based on renewable resources. Replacement of PP- talc composite by PP- saw dust composite is a promising possibility. This paper presents the prep [...] aration of maleated polypropylene (MAPP) through reactive extrusion using different amounts of peroxides and maleic anhydride as well its characterization. Using 20% of saw dust coated with different amounts of prepared MAPP, several composites were prepared including one with commercial MAPP. Injection molded samples of all these composites along with that without the compatibilizer were characterized for mechanical properties. These studies indicated fulfilling the proposed objectives: (i) finding the optimal reactive extrusion conditions to prepare MAPP samples; (ii) preparation of PP/saw dust composites with and without MAPP coating; (iii) to arrive at optimized composite to get the best performance through their characterization for various properties of all the produced composites.

Ernani, Trombetta; Thais, Flores-Sahagun; Kestur G., Satyanarayana.

270

Comparative study between two techniques of incisional hernia repair with polypropylene mesh in rabbits Estudo comparativo entre duas técnicas de tratamento da hérnia incisional em coelhos utilizando a tela de polipropileno  

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Full Text Available PURPOSE: To compare two different incisional hernia repair techniques (repair with a polypropylene mesh reinforcement on the peritonium-aponeurosis versus polypropylene mesh sutured to the borders of the hernial ring as a bridge in rabbits. METHODS: Incisional hernia was experimentally developed through a 4-cm median incision in 60 rabbits. After 30 days, half of the animals were operated for primary wall closure and placement of a polypropylene mesh reinforcement, while the other half had a polypropylene mesh sutured to the borders of the hernial ring as a bridge. Clinical development, scar breaking strength, as well as gross, microscopic and morphometric parameters were evaluated in all animals 30, 60, and 90 days after repair. RESULTS: No significant differences in breaking strength or histological parameters were observed between groups at any time point studied. No statistical difference regarding complications was detected, although denser and firmer adhesions to the abdominal wall were seen after the mesh was placed as a " bridge" . CONCLUSIONS: No significant differences between the incisional hernia repair techniques assessed were observed regarding breaking strength, and histological and morphometric parameters. The number of complications was similar in both study groups. However, adhesion of abdominal cavity organs to the scar area was much denser after the placement of a mesh to bridge the defect.OBJETIVO: Comparar duas técnicas de tratamento da hérnia incisional em coelhos utilizando a tela de polipropileno apoiando um reforço peritônio - aponeurótico ou suturada nas bordas do anel herniário 'em ponte" . MÉTODOS: Foram operados 60 coelhos para a produção de hérnia incisional, em uma incisão mediana de 4 centímetros. Após 30 dias, metade dos animais foram operados com o fechamento primário da parede, com colocação de uma tela de polipropileno apoiando o reforço e a outra metade dos animais com a colocação da tela suturada nas bordas do anel herniário " em ponte" . Os animais foram avaliados com 30 (M1, 60 (M2e 90 (M3 dias de pós-operatório. Os parâmetros analisados foram a evolução clínica, análise da força de ruptura da cicatriz, estudo macroscópico, análise microscópica e morfométrica. RESULTADOS: Não foram observadas diferenças significantes com relação a força de ruptura e estudos histológicos nos dois grupos e vários momentos estudados. Não houve diferença estatística com relação às complicações, embora os animais que receberam a tela " em ponte" tiveram aderências mais firmes e intensas à parede abdominal. CONCLUSÕES: As duas técnicas utilizadas para correção da hérnia incisional em coelhos não mostraram diferenças significantes quanto a força de ruptura, análise histológica e morfométrica. O número de complicações foi semelhante, porém a aderência de órgãos da cavidade abdominal à área de cicatriz foi muito mais intensa no grupo em que a tela foi colocada " em ponte" .

José Guilherme Minossi

2010-10-01

271

Blood flow through sutured and coupled microvascular anastomoses: a comparative computational study.  

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This study uses computational fluid dynamics (CFD) to model blood flow through idealised sutured and coupled arterial anastomoses to investigate the affect of each technique on intravascular blood flow. Local flow phenomena are examined in detail to study characteristics that potentially initiate thrombus formation; for example, changes in velocity profile, wall shear stress (WSS), and shear strain rate (SSR). Idealised geometries of sutured and coupled anastomoses were created with dimensions identical to microvascular suture material and a commercially available coupling device using CFD software. Vessels were modelled as non-compliant 1 mm diameter ducts, and blood was simulated as a Newtonian fluid, in keeping with previous studies. All analyses were steady-state and performed on arteries. The sutured simulation revealed a reduced boundary velocity profile; high WSS; and high SSR at the suture sites. The coupled anastomosis simulation showed a small increase in maximum WSS at the anastomotic region compared to a pristine vessel, however, this was less than half that of the sutured model. The coupled vessel displayed an average WSS equivalent to a pristine vessel simulation. Taken together these observations demonstrate a theoretically more thrombogenic profile in a sutured anastomosis when compared to a coupled vessel. Data from simulations on a coupled anastomosis reveal a profile that is nearly equivalent to that of a pristine vessel. Based purely on the combination of less favourable flow properties shown using these idealised arterial models, the sutured method is potentially more thrombogenic than a coupled anastomosis. PMID:24731801

Wain, Richard A J; Whitty, Justin P M; Dalal, Milind D; Holmes, Michael C; Ahmed, Waqar

2014-07-01

272

Prospective randomized controlled trial investigating the type of sutures used during hepatectomy  

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Full Text Available AIM: To determine whether absorbable sutures or non-absorbable sutures are better in preventing surgical site infection (SSI, in this paper we discuss the results of a randomized clinical trial which examined the type of sutures used during hepatectomy. METHODS: All hepatic resections performed from January 2007 to November 2008 at the Department of Surgery at Iizuka Hospital in Japan were included in this study. There were 125 patients randomly assigned to an absorbable sutures (Vicryl group or non-absorbable sutures (Silk group. RESULTS: SSI was observed in 13.6% (17/125 patients participating in this study, 11.3% in the Vicryl group and 15.8% in the Silk group. Incisional SSI including superficial and deep SSI, was observed in 8% of the Vicryl group and 9.5% of the Silk group. Organ/space SSI was observed in 3.2% of the Vicryl group and 6.0% of the Silk group. There were no significant differences, but among the patients with SSI, the period for recovery was significantly shorter for the Vicryl group compared to the Silk group. CONCLUSION: The incidence of SSI in patients receiving absorbable sutures and silk sutures is not significantly different in this randomized controlled study; however, the period for recovery in patients with SSI was significantly shorter for absorbable sutures.

Norifumi Harimoto

2011-01-01

273

Modification of Siepser sliding suture technique for iris repair and endothelial keratoplasty.  

Science.gov (United States)

We describe a technique for closed-chamber iris repair that prevents knot and suture tail exposure into the anterior chamber. This modification of the Siepser sliding slipknot suture technique is particularly important in the setting of combined or future endothelial keratoplasty to prevent mechanical damage to donor endothelium during transplantation. PMID:24767906

Schoenberg, Evan D; Price, Francis W

2014-05-01

274

Comparison of effects of suture and cyanoacrylate tissue adhesive on bacterial counts in contaminated lacerations.  

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We studied the effects of closing lacerations with suture or cyanoacrylate tissue adhesive on staphylococcal counts in inoculated guinea pig lacerations. Wounds closed with adhesive alone had lower counts than wounds containing suture material (P < 0.05). The results of a time-kill study were consistent with a bacteriostatic adhesive effect of the adhesive against Staphylococcus aureus.

Howell, J. M.; Bresnahan, K. A.; Stair, T. O.; Dhindsa, H. S.; Edwards, B. A.

1995-01-01

275

A novel technique of rotator cuff repair using spinal needle and suture loop  

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Full Text Available Abstract Background We present a simple technique of arthroscopic rotator cuff repair using a spinal needle and suture loop. Methods With the arthroscope laterally, a spinal needle looped with PDS is inserted percutaneously into the shoulder posteriorly and penetrated through the healthy posterior cuff tear margin. Anteriorly, another spinal needle loaded with PDS is inserted percutaneously to engage the healthy tissue at the anterior tear margin. The suture in the anterior needle is then delivered into the suture loop of the posterior needle using a suture retriever. The posterior needle and loop are then pulled out carrying the anterior suture with it. The two limbs of this suture are then retrieved through a cannula for knotting. The same procedure is then repeated for additional suturing. Suture anchors placed over the greater tuberosity are used to complete the repair. Conclusion This is an easy method of rotator cuff repair using simple instruments and lesser time, hence can be employed at centers with less equipment and at reduced cost to the patient.

Muzaffar Nasir

2010-11-01

276

Biomechanical Features of Bidirectional-barbed Suture: A Randomized Laboratory Analysis.  

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The aim of the current prospective study was to evaluate the biomechanical stability of barbed suture vs. conventional suture. Biomechanical stability of a 14x14-cm PDO/polydioxanone, with a half circle and 36-mm needle, bidirectional barbed 0-Quill suture (Angiotech, Vancouver, British Columbia, Canada) vs. 1-Poliglecaprone 25 (Monocryl, Ethicon, Inc, Somerville, NJ) suture was evaluated on biological specimens. The 1-Monocryl suture was chosen because it is widely used by gynecological surgeons in the repair either of the vaginal cuff or the uterine wall defects. Forty specimens of aponeurotic muscle, obtained from abdominal wall of a lamb, were prepared, and randomly assigned to 1 of 2 repair groups: Group A (n = 20) classic repair with 1-Monocryl suture; Group B (n = 20) 0-Quill barbed suture. Each specimen was transected at the midpoint and then repaired. Biomechanical stability of the repaired specimen was verified on a CMT6000 electromechanical universal testing machine (SANS, MTS SYSTEMS, China Co., Ltd., Shenzhen, China), with a 1kN cell. Biomechanical tests showed that maximum force was similar for 1-Monocryl and 0-Quill respectively (p = non-significant). This randomized laboratory study shows that biomechanical stability of the sutures is comparable. PMID:24700213

Castaldi, Maria Antonietta; Cobellis, Luigi; Fraternali, Fernando; Ardovino, Mario; Ardovino, Italo; Colacurci, Nicola

2014-03-01

277

Use of suture anchors in the reconstruction of soft tissue defects with pedicled muscle flaps.  

Science.gov (United States)

Suture anchors have been commercially developed to facilitate stable attachment of soft tissues to bone. Although their use is well characterized in orthopedic literature, suture anchors may also be of benefit in the reconstruction of large soft tissue defects by plastic surgeons. Suture anchors (Mitek Surgical Products, Inc., Westwood, MA) were used to fasten pedicled muscle flaps to exposed bone in 7 patients at Duke University undergoing reconstruction of large soft tissue defects. The suture anchor appeared to provide stability for the advancement flap, and there were no suspected postoperative muscle dehiscences or suture breakages. The suture anchor provides an easy, secure method to attach soft tissue to exposed bone, and preliminary experience appears to support their use in certain soft tissue reconstruction procedures by plastic surgeons. Suture anchors should be reserved for cases in which a large muscle flap is needed to cover exposed bone and poses a risk of shearing away from the bone, or adequate periosteum and soft tissue is not available for standard suture techniques. PMID:16186705

Ravin, Adam G; Gonyon, Denis L; Levin, L Scott

2005-10-01

278

Effect of gamma irradiation on the enzymatic degradation of polyglycolic acid absorbable sutures  

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The effect of gamma irradiation on the enzymatic as well as the in vivo degradation of polyglycolic acid sutures was examined. The sutures of size 2-0 were irradiated at dosage levels of 0-20 mrad. The three enzymes chosen for this study were esterase, alpha-chymotrypsin, and trypsin. The irradiated sutures were both immersed in the enzyme solutions; their corresponding buffer controls, and implanted in inbred black-and-white hooded hister rats (Liverpool strain). The degradation of PGA sutures was determined mechanically. Among the three enzymes studied, esterase showed the highest enzymatic effect on the degradation of the unirradiated and irradiated PGA sutures. Trypsin's effect on PGA sutures was not observed until 20 mrad. The findings of trypsin demonstrated the hypothesis that synthetic high molecular weight polymers, which are initially resistant to enzymatic degradation, could become prone to enzymatic attack after altering their physical and chemical structures. Implanted PGA sutures maintained a similar or slightly higher mean tensile breaking strength in in vivo degradation compared to in vitro degradation (0.1M tris buffer of pH . 7.5); these degradation profiles suggest that PGA does not display similar behavior in in vivo and in vitro degradations. The magnitude of dissimilarity depends on the radiation dosage and on the duration of degradation, and is speculated to be attributable to the specific action of enzymes with respect to the configuration and chemical structure of the PGA sutures.

Chu, C.C.; Williams, D.F.

1983-11-01

279

The effect of gamma irradiation on the enzymatic degradation of polyglycolic acid absorbable sutures.  

Science.gov (United States)

The purpose of the study was to examine the effect of gamma irradiation on the enzymatic as well as the in vivo degradation of polyglycolic acid sutures. The sutures of size 2-0 were irradiated at dosage levels of 0-20 mrad. The three enzymes chosen for this study were esterase, alpha-chymotrypsin, and trypsin. The irradiated sutures were both immersed in the enzyme solutions; their corresponding buffer controls, and implanted in inbred black-and-white hooded hister rats (Liverpool strain). The degradation of PGA sutures was determined mechanically. Among the three enzymes studied, esterase showed the highest enzymatic effect on the degradation of the unirradiated and irradiated PGA sutures. Trypsin's effect on PGA sutures was not observed until 20 mrad. The findings of trypsin demonstrated the hypothesis that synthetic high molecular weight polymers, which are initially resistant to enzymatic degradation, could become prone to enzymatic attack after altering their physical and chemical structures. Implanted PGA sutures maintained a similar or slightly higher mean tensile breaking strength in in vivo degradation compared to in vitro degradation (0.1M tris buffer of pH = 7.5); these degradation profiles suggest that PGA does not display similar behavior in in vivo and in vitro degradations. The magnitude of dissimilarity depends on the radiation dosage and on the duration of degradation, and is speculated to be attributable to the specific action of enzymes with respect to the configuration and chemical structure of the PGA sutures. PMID:6317694

Chu, C C; Williams, D F

1983-11-01

280

The Roman Bridge: a "double pulley – suture bridges" technique for rotator cuff repair  

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Full Text Available Abstract Background With advances in arthroscopic surgery, many techniques have been developed to increase the tendon-bone contact area, reconstituting a more anatomic configuration of the rotator cuff footprint and providing a better environment for tendon healing. Methods We present an arthroscopic rotator cuff repair technique which uses suture bridges to optimize rotator cuff tendon-footprint contact area and mean pressure. Results Two medial row 5.5-mm Bio-Corkscrew suture anchors (Arthrex, Naples, FL, which are double-loaded with No. 2 FiberWire sutures (Arthrex, Naples, FL, are placed in the medial aspect of the footprint. Two suture limbs from a single suture are both passed through a single point in the rotator cuff. This is performed for both anchors. The medial row sutures are tied using the double pulley technique. A suture limb is retrieved from each of the medial anchors through the lateral portal, and manually tied as a six-throw surgeon's knot over a metal rod. The two free suture limbs are pulled to transport the knot over the top of the tendon bridge. Then the two free suture limbs that were used to pull the knot down are tied. The end of the sutures are cut. The same double pulley technique is repeated for the other two suture limbs from the two medial anchors, but the two free suture limbs are used to produce suture bridges over the tendon, by means of a Pushlock (Arthrex, Naples, FL, placed 1 cm distal to the lateral edge of the footprint. Conclusion This technique maximizes the advantages of two techniques. On the one hand, the double pulley technique provides an extremely secure fixation in the medial aspect of the footprint. On the other hand, the suture bridges allow to improve pressurized contact area and mean footprint pressure. In this way, the bony footprint in not compromised by the distal-lateral fixation, and it is thus possible to share the load between fixation points. This maximizes the strength of the repair and provides a barrier preventing penetration of synovial fluid into the healing area of tendon and bone.

Maffulli Nicola

2007-12-01

 
 
 
 
281

The ramp mattress suture: a new suturing technique combined with a surgical procedure to obtain papillae between implants in the buccal area.  

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This article has been written to show the opportunity and eventually the predictability to obtain new papillae between implants and a better esthetic result by the use of a new suturing technique. After raising a full-thickness flap from the palatal to the vestibular side, it can be stabilized in such a position using a new suturing technique (ramp mattress suture) to apply pressure and tearing forces on the flap in an apicocoronal direction at the vestibular site and an opposite traction in a coronoapical direction at the palatal site. The ramp mattress suture seems to be capable of pulling the flap in an apicocoronal direction in the vestibular site, as well as in a coronoapical direction in the palatal site. Thanks to such a mattress suture, it will be possible to obtain a more coronal gingival margin. After an adequate healing period of approximately 5 weeks, a vestibular scalloped gingivectomy is performed around the vestibular surface of the abutment to create either a scalloped gingival margin or interproximal papillae only in the vestibular area, forming a gingival ramp in a palatovestibular direction to reasonably reduce the residual increased vestibular depth and optimize the esthetic result. Eight patients, for a total of 56 papillae, were treated with this new suturing technique. The esthetic results satisfied both clinician and patient expectations. PMID:11922220

Tinti, Carlo; Benfenati, Stefano Parma

2002-02-01

282

Effects of environmental ageing on HMS-polypropylene/Cloisite nanocomposites  

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High melt strength polypropylene Nanocomposites (NC-HMSPP) were obtained with concentrations of 0.1 and 5 wt% of Cloisite 20A. The melt intercalation, using twin screw extruder was done to homogenize the nanocomposite in presence of polypropylene graft maleic anhydride (PP-g-MA) compatibilizer agent. In this work, the manufactured dumbbell samples were settled in device for natural ageing assay. The period of exposition was January to December of 2012. The effects of environmental ageing was determined by carbonyl index (FT-IR) and the results showed that nanocomposites were more stable than HMSPP. The mechanical properties (elongation and rupture strength) were evaluated and the thermal behavior was investigated by differential scanning calorimetry (DSC) and X ray diffraction (DRX). The morphology was observed by scanning electron microscopy (SEM) in which the nanocomposites showed intense cracks on the surface.

Komatsu, L. G. H., E-mail: dfparra@ipen.br; Oliani, W. L., E-mail: dfparra@ipen.br; Ferreto, H. F. R., E-mail: dfparra@ipen.br; Lugao, A. B., E-mail: dfparra@ipen.br; Parra, D. F., E-mail: dfparra@ipen.br [Nuclear and Energy Research Institute, IPEN-CNEN/SP (Brazil)

2014-05-15

283

Analysis of the fracture behavior of polypropylene: sawdust composites  

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Full Text Available SciELO Brazil | Language: English Abstract in english Natural fiber reinforced composite is an emerging area in Polymer science. The use of lignocellulosic materials in thermoplastic composites may contribute to reduce the waste of vegetal biomass. The natural fibers are biodegradable, low cost materials having density and specific properties comparabl [...] e to those of conventional fiber composites. In this work composites of polypropylene (PP) plus maleated polypropylene (MAPP) filled with sawdust were prepared under fixed processing conditions (mixing temperature, mixing time and rate of rotation). The composites were fractured by tension and the fracture mechanisms were characterized by scanning electron microscopy. The SEM studies of the fractured surfaces of the composites indicate that the failure is due to fiber pull-out accompanied by tearing of the matrix; the pull-out increases with MAPP content.

João C. Miguez, Suarez; Fernanda M. B., Coutinho; Thais H., Sydenstricker.

284

Mechanical properties of rubberwood fibers polypropylene epoxidized natural rubber composites  

International Nuclear Information System (INIS)

Research on rubberwood fibers-thermoplastic composites have been carried out by several workers in the past several years. The main focus was to enhance the properties of the resultant composites in view of the incompatibility of the two components. Thus, efforts have been made to enhance their properties by using coupling agents, treating the fibers and modifying the matrices. In this study, the rubberwood polypropylene composite was used as a base material and the addition of epoxidized natural rubber (ENR) is to provide a damping property of the composite with the final aim to produce a sound and noise proofing products. Initially, the processing and compositions of rubberwood fibers and polypropylene was optimized at the 50:50 w/w ratio using melt blend internal mixer. The processing parameters were established. Subsequently, the mechanical properties of the composites were determined with addition of 1-4% of ENR. (Author)

285

Effect of ?-irradiation on the paracrystalline structure of polypropylene film  

International Nuclear Information System (INIS)

Thin isotactic polypropylene film (50 ?m), irradiated in air, has been investigated by infrared (IR) spectroscopy, wide and small angle X-ray diffraction, and light microscopy. Infrared spectra show that the concentrations of carbonyl, hydroxyl, peroxyl and carboxyl groups increase with irradiation dose as well as the content of molecular chains with helical structure. X-ray experiments and light microscopy studies show that the ?-irradiation does not cause any change in the paracrystalline structure and crystallisation is possible after appropriate thermal treatment or melting. It may be concluded that the paracrystalline structure is not sensitive to ?-irradiation up to doses of 370 kGy (37 Mrad). It is believed that changes at the molecular level such as conformational, destructive, crosslinking, oxidation, post-irradiation effects, etc., do not effect the supermolecular smectic structure of thin film samples of polypropylene. (author)

286

POLYPROPYLENE/STARCH BLENDS: STUDY OF THERMAL AND MORPHOLOGICAL PROPERTIES  

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Full Text Available SciELO Chile | Language: English Abstract in english Polypropylene/starch blends were prepared using starch of different botanical source. The influence of starch type and starch content on thermal properties and morphology of polypropylene/starch blends was studied. Corn and potato starches were used as starch source. The starch content in the blends [...] was 7 and 15 wt-%. Characterization of PP and PP/starch blends by (DSC), (TGA), and (SEM) was carried out to obtain information on miscibility among PP and starch. The starch domains exhibited characteristic voids be due to thermal degradation. Two types of PP, PP1 poly(propylene-co-ethylene), random copolymer, and PP3 poly(propylene-co-ethylene), heterophasic copolymer were studied.

MONICA A, PÉREZ R; BERNABÉ L, RIVAS Q; SADDYS, RODRÍGUEZ-LLAMAZARES.

287

POLYPROPYLENE/STARCH BLENDS: STUDY OF THERMAL AND MORPHOLOGICAL PROPERTIES  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Polypropylene/starch blends were prepared using starch of different botanical source. The influence of starch type and starch content on thermal properties and morphology of polypropylene/starch blends was studied. Corn and potato starches were used as starch source. The starch content in the blends [...] was 7 and 15 wt-%. Characterization of PP and PP/starch blends by (DSC), (TGA), and (SEM) was carried out to obtain information on miscibility among PP and starch. The starch domains exhibited characteristic voids be due to thermal degradation. Two types of PP, PP1 poly(propylene-co-ethylene), random copolymer, and PP3 poly(propylene-co-ethylene), heterophasic copolymer were studied.

MONICA A, PÉREZ R; BERNABÉ L, RIVAS Q; SADDYS, RODRÍGUEZ-LLAMAZARES.

1643-16-01

288

DSC Study on Polypropylene Modified with Calcium Carbonate Nanoparticles  

International Nuclear Information System (INIS)

The exposure of polypropylene containing various concentrations of calcium carbonate nanoparticles was performed in air and water. The radiolysis products of water determine different behaviour of polymer substrate. The irradiation effect induced on polymer and the contribution of nanoparticles to the scavenging of oxygenated products that were created during ? exposure were investigated by DSC measurements over the temperature range from 340-400 K, the usual temperatures for thermal overcharge. Two kinds of carbonate particles, one type is represented by unmodified filler, while the second type is the superficially modified with stearic acid. The covering of particle surface with stearic acid confers to them a different ability in the abstraction of degradation products formed in irradiated isotactic polypropylene

289

Effects of environmental ageing on HMS-polypropylene/Cloisite nanocomposites  

International Nuclear Information System (INIS)

High melt strength polypropylene Nanocomposites (NC-HMSPP) were obtained with concentrations of 0.1 and 5 wt% of Cloisite 20A. The melt intercalation, using twin screw extruder was done to homogenize the nanocomposite in presence of polypropylene graft maleic anhydride (PP-g-MA) compatibilizer agent. In this work, the manufactured dumbbell samples were settled in device for natural ageing assay. The period of exposition was January to December of 2012. The effects of environmental ageing was determined by carbonyl index (FT-IR) and the results showed that nanocomposites were more stable than HMSPP. The mechanical properties (elongation and rupture strength) were evaluated and the thermal behavior was investigated by differential scanning calorimetry (DSC) and X ray diffraction (DRX). The morphology was observed by scanning electron microscopy (SEM) in which the nanocomposites showed intense cracks on the surface

290

Strength of polyethylene, polypropylene and polystyrene behind a shock front  

International Nuclear Information System (INIS)

There is a recent interest in the response of thermoplastics to shock. Previous work on three simple hydrocarbons has indicated that the shear strength increases with the complexity of the side group. Strength values have been calculated using lateral stress measurements with manganin gauges that have been recalibrated for use in the low stress regime. The present work aims to investigate the effect of the configuration of the thermoplastic's chain when side groups are added. Results show that whilst polyethylene has the lowest shear strength, polypropylene and polystyrene have similar values. In all cases the strength of polymer increases with time after the shock has past. As the applied stress increases, polystrene and polypropylene strengthen to a higher degree when compared with polyethylene. Explanations are offered in terms of microstructure and tacticity of the chain

291

Radiation effects in ricinyl-2-oxazoline maleate-modified polypropylene  

International Nuclear Information System (INIS)

Polypropylene (PP) and ricinyl-2-oxazoline maleate-modified polypropylene were irradiated with a 10-MeV electron beam (from a LAE 13/9 linear accelerator). The resulting radicals were studied by electron paramagnetic resonance spectroscopy (EPR). The chemical modification of PP was found to have affected the mechanism of radical formation. The chemical and radiative modification of PP was found to proceeded through the formation of proxy rather than alkyl radicals. The incorporation of ricinyl-2 oxazoline maleate into PP chain- and the degradation of the PP chain by the fast electron beam resulted in a modified melt flow rate index (MFR), viscosity and thermal properties as evidenced by DSC. (author)

292

Lateral intercrural suture in the caucasian nose: Decreased domal divergence angle in endonasal rhinoplasty without delivery  

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Full Text Available Introduction: Several techniques can be performed to improve nasal tip definition such as cartilage resection, tip grafts, or sutures. Objective: To evaluate the outcome of lateral intercrural suture at the lower lateral cartilage by endonasal rhinoplasty with a basic technique without delivery in decreasing the angle of domal divergence and improving the nasal tip definition. Method: This prospective study was performed in 64 patients in which a suture was made on the board head of the lower lateral cartilage in the joint between the dome and lateral crus, using polydioxanone (PDS with sharp, curved needle. Results: In all of the cases, better definition of the nasal tip was achieved by intercrural suturing for at least 6 months postoperatively. Conclusion: Lateral intercrural suture of the lower lateral cartilage provides improved nasal tip definition and can be performed by endonasal rhinoplasty without delivery in the Caucasian nose.

Berger, Cezar Augusto Sarraf

2012-01-01

293

Comparative trial of Dexon (polyglycolic acid), collagen, and silk sutures in ophthalmic surgery.  

Science.gov (United States)

The tissue reaction, absorption, and handling properties of Dexon synthetic absorbable sutures, which are made from polymerized hydroxyacetic acid, were compared with those of silk and collagen in 51 eye operations, consisting mainly of cataract extractions and squint corrections. There was no significant difference between the sutures as regards degree of tissue reaction. The Dexon sutures were very strong and the knots held well. The sizes used in this series were found to be a little too thick and stiff for use in micro-surgery; smaller sizes would be easier to use and still remain strong enough. The Dexon was reliably absorbed in 5 weeks on average. No serious adverse reactions were seen with any of the sutures. Dexon was as well tolerated as the control sutures but had the advantage over silk of being absorbed and over collagen of containing no foreign protein. PMID:766826

Chatterjee, S

1975-12-01

294

Modification of bentonite clay and application on polypropylene nano composites  

International Nuclear Information System (INIS)

This work consisted on the modification of Brasgel PA clay with ionic surfactant Praepagen WB and its incorporation into polypropylene. The results of infrared and DR-X was showed that the intercalation of surfactant in the clay and the incorporation of organoclay in PP matrix resulted in the formation of an intercalated structure. The impact strength of PP increased with the incorporation of organoclay. (author)

295

[Toxicity of products resulting from the cold combustion of polypropylene].  

Science.gov (United States)

The cool flame combustion of polypropylene at 350 degrees C leads to the formation of toxic compounds which can cause death in mice. Under the conditions described, the LD50 is close to 0.95 g. However the survival times with 0.50 g samples are longer than those obtained by operating in an ambient atmosphere at 500 degrees and 800 degrees C after a slow introduction of the material into the oven. PMID:6817858

Chaigneau, M; Le Moan, G

1982-09-27

296

GC-MS OF POLYETHYLENE AND POLYPROPYLENE THERMAL CRACKING PRODUCTS  

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Low-density polyethylene and polypropylene were thermally decomposed individually in a batch reactor at 450°C as a recycling route from the aspect of the production of petrochemical feedstock. The resulting transformation liquid products were analysed by high resolution gas chromatographic-mass spectrometric analysis. More detailed separation of polyalkenes splitting compounds was achieved using high resolution GC (efficiencies up to 490 000 plates) than before. The GC-MS as well as the depe...

Martin Bajus; Elena Hájeková; Helena Jurdáková; Robert Kubinec; Ladislav Soják

2006-01-01

297

Functional Block Copolymers as Compatibilizers for Nanoclays in Polypropylene Nanocomposites  

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With the aim of creating tough nanocomposits (NC) [1] based on polypropylene (PP) and nanoclay (NCl) in the framework of the 7th EU program NANOTOUGH we have designed amphiphilic block copolymers utilizing Atom Transfer Radical Polymerization (ATRP) [2]. They consist of a hydrophobic block of Kraton L-1203 from Kuraray Co., Japan with molecular weight 7000 and PDI=1.05, and a hydrophilic block of quaternized dimethylaminoethyl methacrylate (DMAEMA). The size of the hydrophilic block was varie...

Jankova Atanasova, Katja; Daugaard, Anders Egede; Stribeck, Norbert; Zeinolebadi, Ahmad; Sari, Morteza Ganjaee; Potarniche, Catalina-gabriela; Jensen, Erik Appel; Christiansen, Jesper Claville; Hvilsted, Søren

2011-01-01

298

Microstructure and mechanical properties of Polypropylene/Polycarbonate blends  

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Purpose: Researches, which are presented in this paper, consider the effect of chosen different weight ratios polycarbonate blended in a polypropylene matrix (PP/PC) at variable injection moulding conditions and its effect on the microstructure, and also on fracture and flexural properties.Design/methodology/approach: Composites contain between 0 and 30 wt % of polycarbonate and changes at constant rate of 10wt%. Specimens were produced with advantage of melt manipulation technology, further ...

Viana, J. C.; Bilewicz, M.; Kro?l, M.; Dobrzan?ski, L. A.

2008-01-01

299

Compression of polypropylene across a wide range of strain rates  

Science.gov (United States)

Three grades of polypropylene were tested in uniaxial compression at room temperature, across a wide range of strain rate: 10-4 s-1 to 104 s-1. One grade is a conventional polypropylene homopolymer. The two other grades are the polypropylene forming the matrix phase of a continuous glass fibre-reinforced thermoplastic composite prepreg, with and without blending with a carbon-black master batch. Tests at the highest strain rates were performed using a compression split Hopkinson pressure bar. The test specimens, for all the three rates, were imaged using appropriate digital cameras in order to observe the deformation process. In addition, the images obtained were analysed digitally to obtain true strain measurements for the medium rates category. All three grades of polypropylene showed pronounced strain-rate dependence of compressive yield stress, increasing by factors of up to 4 across the range of rates. At the lowest rates, there was close agreement between the yield stresses for all three materials, and also close agreement with the Eyring theory. Considering the highest strain rates, however, yield stresses increased more rapidly with log(strain-rate) than would be expected from a linear Eyring prediction and values for the three materials diverged. This was attributed to the contributions made in each material by both alpha and beta relaxation processes. Also prominent in the medium- and high-rate experimental results was pronounced post-yield strain softening, greatest at the highest strain-rates. This resulted from a combination of thermal softening from adiabatic heating, and structural rejuvenation as often seen in glassy polymers in quasi-static tests.

Okereke, M. I.; Buckley, C. P.; Siviour, C. R.

2012-11-01

300

Reinforcing Efficiency of Crimped Profile of Polypropylene Fibres on the Cementitious Matrix  

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Fibre reinforcement in concrete is an effective solution for improving tensile properties of concrete. Different types of fibres such as steel, polypropylene, glass and polyester were commonly used in concrete. In the present study, the effect of adding crimped polypropylene fibres on the improvement in the compressive properties of hardened concrete was studied. Crimped polypropylene fibres with different levels of reinforcements index was investigated systematically with designed concrete m...

Thirumurugan, S.; Sounthararajan, V. M.; Sivakumar, A.

2013-01-01

 
 
 
 
301

Investigating the Effect of Nanoclay on Polypropylene-Made Cellulose Composite  

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This study investigates the effect of adding the nanoclay particles on the mechanical properties of polypropylene-made cellulose composite. Based-on-polypropylene composites are mixed with the particles of wheat stalk flour with the dimensional size (mesh 80), nanoclay at three different levels (0, 2 and 4) per hundred compounds (phc) and also with Maleic Anhydride-grafted Polypropylene (MAPP) as compatibilizer by Dr. Colin machine at 180°C and 60 rpm and the standard test samples were made ...

Naeli Shokoufa; Nourbakhsh Amir; Ghodrati Ashkan; Talaeipour Mohammad; Khademi-Eslam; Habibollah

2013-01-01

302

Effect of recycling on properties of rice husk-filled-polypropylene  

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This research concerned with the use of rice husk (Oryza sativa) as a filler for polypropylene and its recycle ability. Rice husk (200 mesh and 40% by weight) and polypropylene were compounded in a twinscrew extruder and injection moulding technique was applied in order to obtain testing specimens. It was found that tensile, flexural and impact properties as well as % water absorption of the rice husk-filled polypropylene were only slightly dropped upon recycling process, presenting the abili...

Jutarat Prachayawarakorn; Niracha Yaembunying

2005-01-01

303

End-on extramucosal single layer suture with double anchoring in the submucosa on rabbits  

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Full Text Available The techniques of gastrointestinal surgical sutures have been frequently focused in controversial publications. These ones concern not only anastomosis? types but also about thread types and how to apply them. The values of the submucosa as layer of greatest resistence of the digestive tube was already known since the past century. The aim of this study is to avaluate the suture in an extramucosal single-layer suture with double anchoring of the submucosa, a technical detail not found in the searched literature. This experiment was carried out using 36 white,male adults New Zealand, rabbits divided into three groups which differed only regarding day of re-operation and euthanasia, as followed: group I ( 4 days, group II (7 days and group III ( 15 days. Two transversal and parallel gastrotomies were perfomed in the same animal, one distal and other proximal, of with 4 cm extension each. In these gastrotomies two types of sutures were alternated : 1- End-on extramucosal single-layer suture and 2- End-on extramucosal single-layer suture, with double anchoring in the submucosa. Macroscopic and microscopic studies were perfomed on the suture line in both gastrotomies and in each period of euthanasia. Except for the serosa item whose results were similar for both sutures, statiscally, the extramucosal single-layer suture, with double anchoring of submucosa layer showed better macro and microscopic results than the extramucosal single-layer suture in group I (4 days. In the others periods of euthanasia (groups II and III, the statistical results were similar.

Nascimento Luiz Roberto do

1999-01-01

304

Transcutaneous Serdev Suture For Buttock’s Lift  

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Full Text Available This article presents the author's technique and experience in the treatment of the flaccid "unhappy buttock" form with his surgical procedure of buttock lift by suture, without incision scars. The author first presented this new operation technique on a national level at the 2nd Annual Meeting of the National Bulgarian Society for Aesthetic Surgery and Aesthetic Medicine in Sofia on March 18, 1994 [1] and internationally at many scientific meetings over the world [2, 3, 4…]. The result is a visual change in the buttock position to a higher one, which elongates the lower limbs and changes the proportions between lower and upper half of the body. The aim of this study is to describe a mini-invasive procedure of beautification of the buttock form without scars by creating a lifting effect on the buttock's subcutaneous tissue, using a suture that takes the inferiorly positioned deep fibrose tissue and fixes it upwards to the sacro-cutaneous fascia, discovered by the author. Aesthetic and technical considerations required properly sculpting the buttocks into a higher position, demonstrating nicely rounded form. Preoperative shape is discussed and patient evaluations, operative techniques, postoperative management and results after 4 years of experience are emphasized. 1032 female patients, and 26 male patients aged 18-62 years, with ptosis and cellulite on the buttocks were treated since 1993 on an outpatient basis by the "Serdev suture technique without visible scars". Important instrumentarium is a long, curved, elastic needle and Polycon semi-elastic Bulgarian antimicrobial polycaproamide long term (in 2 years absorbable surgical threads Polycon, produced in Bulgaria. This operation has been performed either alone or after ultrasonic assisted liposculpture (UAL that reduces the amount of fat and heaviness. All patients reported a high degree of satisfaction. A stable improvement in the buttock position and form was observed for the period described. In the postoperative period the complication rate was minimal and resolved in the first 4-5 days post operative period. The skin puncture in the perianal zone makes antibiotic prophylaxis obligatory as well as a strict follow up for the first 7 days. Some pain in the sitting position was observed for at least 5 to 10 days, but all other social and professional duties and activities were possible. This outpatient procedure is effective in the correction of buttock laxity and ptosis and creates a new form, universally accepted as "happy buttocks".

Nikolay Serdev

2013-10-01

305

Celastrol nanoparticles inhibit corneal neovascularization induced by suturing in rats  

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Full Text Available Zhanrong Li1, Lin Yao1, Jingguo Li2, Wenxin Zhang1, Xianghua Wu1, Yi Liu1, Miaoli Lin1, Wenru Su1, Yongping Li1, Dan Liang11State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, 2School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, People's Republic of ChinaPurpose: Celastrol, a traditional Chinese medicine, is widely used in anti-inflammation and anti-angiogenesis research. However, the poor water solubility of celastrol restricts its further application. This paper aims to study the effect of celastrol nanoparticles (CNPs on corneal neovascularization (CNV and determine the possible mechanism.Methods: To improve the hydrophilicity of celastrol, celastrol-loaded poly(ethylene glycol-block-poly(?-caprolactone nanopolymeric micelles were developed. The characterization of CNPs was measured by dynamic light scattering and transmission electron microscopy analysis. Celastrol loading content and release were assessed by ultraviolet-visible analysis and high performance liquid chromatography, respectively. In vitro, human umbilical vein endothelial cell proliferation and capillary-like tube formation were assayed. In vivo, suture-induced CNV was chosen to evaluate the effect of CNPs on CNV in rats. Immunohistochemistry for CD68 assessed the macrophage infiltration of the cornea on day 6 after surgery. Real-time quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay were used to evaluate the messenger ribonucleic acid and protein levels, respectively, of vascular endothelial growth factor, matrix metalloproteinase 9, and monocyte chemoattractant protein 1 in the cornea.Results: The mean diameter of CNPs with spherical shape was 48 nm. The celastrol loading content was 7.36%. The release behavior of CNPs in buffered solution (pH 7.4 showed a typical two-phase release profile. CNPs inhibited the proliferation of human umbilical vein endothelial cells in a dose-independent manner and suppressed the capillary structure formation. After treatment with CNPs, the length and area of CNV reduced from 1.16 ± 0.18 mm to 0.49 ± 0.12 mm and from 7.71 ± 0.94 mm2 to 2.29 ± 0.61 mm2, respectively. Macrophage infiltration decreased significantly in the CNP-treated corneas. CNPs reduced the expression of vascular endothelial growth factor, matrix metalloproteinase 9, and monocyte chemoattractant protein 1 in the cornea on day 6 after suturing.Conclusion: CNPs significantly inhibited suture-induced CNV by suppressing macrophage infiltration and the expression of vascular endothelial growth factor and matrix metalloproteinase 9 in the rat cornea.Keywords: celastrol, PEG-b-PCL nanopolymeric micelles, corneal neovascularization, macrophages, VEGF, MMP-9

Li ZR

2012-03-01

306

Rheological study of polypropylene irradiated with polyfunctional monomers  

International Nuclear Information System (INIS)

The aim of this paper is to investigate the rheological properties of polypropylene (PP) modified by ionization radiation (gamma rays) in the presence of two different monomers. The samples were mixed in a twin-screw extruder with ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TMPTMA) with concentration in the range of 0.5-5.0 mmol. After that, they were irradiated with 20 kGy dose of gamma radiation. The structural modification of polypropylene was analyzed in the melt state by measuring melt flow rate (MFR), ?* (complex viscosity) and G' (storage modulus) in the angular frequency range of 10-1 to 3 x 102 rad s-1. From the oscillatory rheology data, one could obtain the values of ?0 (zero shear viscosity) that would be related to the molar mass. All results were discussed with respect to the crosslinking and degradation process that occur in the post-reactor treatment to produce controlled rheology polypropylene. The resulting polymeric materials were submitted the cytotoxicity in vitro test by neutral red uptake methodology with NCTC L 929 cell line from American Type Culture Collection bank. All modified PP samples presented no cytotoxicity

307

Rheological study of polypropylene irradiated with polyfunctional monomers  

Energy Technology Data Exchange (ETDEWEB)

The aim of this paper is to investigate the rheological properties of polypropylene (PP) modified by ionization radiation (gamma rays) in the presence of two different monomers. The samples were mixed in a twin-screw extruder with ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TMPTMA) with concentration in the range of 0.5-5.0 mmol. After that, they were irradiated with 20 kGy dose of gamma radiation. The structural modification of polypropylene was analyzed in the melt state by measuring melt flow rate (MFR), {eta}* (complex viscosity) and G' (storage modulus) in the angular frequency range of 10{sup -1} to 3 x 10{sup 2} rad s{sup -1}. From the oscillatory rheology data, one could obtain the values of {eta}{sub 0} (zero shear viscosity) that would be related to the molar mass. All results were discussed with respect to the crosslinking and degradation process that occur in the post-reactor treatment to produce controlled rheology polypropylene. The resulting polymeric materials were submitted the cytotoxicity in vitro test by neutral red uptake methodology with NCTC L 929 cell line from American Type Culture Collection bank. All modified PP samples presented no cytotoxicity.

Otaguro, H.; Rogero, S.O.; Yoshiga, A.; Lima, L.F.C.P.; Parra, D.F. [IPEN/CNEN - Instituto de Pesquisas Energeticas e Nucleares, Av. Professor Lineu Prestes, 2242, CEP 05508-000 - Cidade Universitaria, Sao Paulo, SP (Brazil); Artel, B.W.H. [EMBRARAD - Empresa Brasileira de Radiacoes Ltda, Av. Cruzada Bandeirante, 269, CEP 06705-140 - Cotia (Brazil); Lugao, A.B. [IPEN/CNEN - Instituto de Pesquisas Energeticas e Nucleares, Av. Professor Lineu Prestes, 2242, CEP 05508-000 - Cidade Universitaria, Sao Paulo, SP (Brazil)], E-mail: ablugao@ipen.br

2007-12-15

308

Rheological study of polypropylene irradiated with polyfunctional monomers  

Science.gov (United States)

The aim of this paper is to investigate the rheological properties of polypropylene (PP) modified by ionization radiation (gamma rays) in the presence of two different monomers. The samples were mixed in a twin-screw extruder with ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TMPTMA) with concentration in the range of 0.5-5.0 mmol. After that, they were irradiated with 20 kGy dose of gamma radiation. The structural modification of polypropylene was analyzed in the melt state by measuring melt flow rate (MFR), ?* (complex viscosity) and G' (storage modulus) in the angular frequency range of 10 -1 to 3 × 10 2 rad s -1. From the oscillatory rheology data, one could obtain the values of ?0 (zero shear viscosity) that would be related to the molar mass. All results were discussed with respect to the crosslinking and degradation process that occur in the post-reactor treatment to produce controlled rheology polypropylene. The resulting polymeric materials were submitted the cytotoxicity in vitro test by neutral red uptake methodology with NCTC L 929 cell line from American Type Culture Collection bank. All modified PP samples presented no cytotoxicity.

Otaguro, H.; Rogero, S. O.; Yoshiga, A.; Lima, L. F. C. P.; Parra, D. F.; Artel, B. W. H.; Lugão, A. B.

2007-12-01

309

Pubovaginal sling with a low-cost polypropylene mesh  

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Full Text Available OBJECTIVE: The aim of this study was to present the results of pubovaginal sling with a low-cost polypropylene mesh in the treatment of stress urinary incontinence MATERIALS AND METHODS: 118 women diagnosed with stress urinary incontinence (SUI due to urethral hypermobility or intrinsic sphincteric deficiency, treated with pubovaginal sling (PVS with a low-cost polypropylene mesh confectioned by the surgeon, were analyzed. All patients had a basic evaluation that included a medical history, physical examination, stress tests and urodynamic investigation RESULTS: The average follow up was of 42 months. Urethral hypermobility was observed in 67% of the cases. The process was carried out on an outpatient basis on 67 patients. Intra-operative complications included 4 vesical injuries, treated with catheterization for 3 days. There were 13 early complications, of which 8 were urinary retentions treated with vesical drainage for 1 to 3 weeks and 3 vaginal extrusions of the mesh treated with covering of the sections with mucous membrane. There was a need for 6 urethrolysis in patients who presented irritative and postoperative obstructive symptoms; 81.3% of the patients were considered cured, while 9.3% had significant improvement. Three initially unsuccessful cases required sling reconfiguration. All cases were eventually cured CONCLUSION: The construction of a pubovaginal sling using a low-cost polypropylene mesh is a safe and effective technique for the relief of SUI. It should be considered an alternative, especially for patients in public health systems with low financial resources.

Fransber R. Rodrigues

2007-10-01

310

Development and characterisation of injection moulded, all-polypropylene composites  

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Full Text Available In this work, all-polypropylene composites (all-PP composites were manufactured by injection moulding. Prior to injection moulding, pre-impregnated pellets were prepared by a three-step process (filament winding, compression moulding and pelletizing. A highly oriented polypropylene multifilament was used as the reinforcement material, and a random polypropylene copolymer (with ethylene was used as the matrix material. Plaque specimens were injection moulded from the pellets with either a film gate or a fan gate. The compression moulded sheets and injection moulding plaques were characterised by shrinkage tests, static tensile tests, dynamic mechanical analysis and falling weight impact tests; the fibre distribution and fibre/matrix adhesion were analysed with light microscopy and scanning electron microscopy. The results showed that with increasing fibre content, both the yield stress and the perforation energy significantly increased. Of the two types of gates used, the fan gate caused the mechanical properties of the plaque specimens to become more homogeneous (i.e., the differences in behaviour parallel and perpendicular to the flow direction became negligible.

A. Kmetty

2013-02-01

311

Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites  

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Full Text Available Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. Rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes.

Alejandra J. Monsiváis-Barrón

2014-10-01

312

Mixing of Isotactic and Syndiotactic Polypropylenes in the Melt  

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The miscibility of polypropylene (PP) melts in which the chains differ only in stereochemical composition has been investigated by two different procedures. One approach used detailed local information from a Monte Carlo simulation of a single chain, and the other approach takes this information from a rotational isomeric state model devised decades ago, for another purpose. The first approach uses PRISM theory to deduce the intermolecular packing in the polymer blend, while the second approach uses a Monte Carlo simulation of a coarse-grained representation of independent chains, expressed on a high-coordination lattice. Both approaches find a positive energy change upon mixing isotactic PP (iPP) and syndiotactic polypropylene (sPP) chains in the melt. This conclusion is qualitatively consistent with observations published recently by Muelhaupt and coworkers. The size of the energy chain on mixing is smaller in the MC/PRISM approach than in the RIS/MC simulation, with the smaller energy change being in better agreement with the experiment. The RIS/MC simulation finds no demixing for iPP and atactic polypropylene (aPP) in the melt, consistent with several experimental observations in the literature. The demixing of the iPP/sPP blend may arise from attractive interactions in the sPP melt that are disrupted when the sPP chains are diluted with aPP or iPP chains.

CLANCY,THOMAS C.; PUTZ,MATHIAS; WEINHOLD,JEFFREY D.; CURRO,JOHN G.; MATTICE,WAYNE L.

2000-07-14

313

Contact angle analysis of corona treated polypropylene films  

International Nuclear Information System (INIS)

In this work, the effect of the surface modification of polypropylene films via corona treatment was investigated. Polypropylene films were treated with negative and positive corona discharge, at atmospheric pressure, for 5 minutes, at two different temperatures – 25 °C and 90 °C. The changes in the surface free energy were investigated by means of contact angle measurements. The Bickerman's method was applied to determine the polar and dispersion components of the polymer surface free energy, on the basis of the theory of Owens, Wendt, Kaelble and Uy. Atomic force microscopy was used to analyze the polymer surface morphology changes of the films with temperature. According to the findings, in all cases the corona treatment increases the surface free energy of polypropylene films and its polar part, in comparison with the untreated samples. The effects of negative and positive corona polarities display some specific features which could be associated with different charged group introduced onto the film surface during the corona treatment. The total final effect depends on the simultaneous action of the two competing factors – temperature and corona polarity. The most pronounced effect was observed for high temperature negative corona treatment.

314

Study of polypropylene/polybutene blends submitted to ionizing radiation  

International Nuclear Information System (INIS)

PP has been used in various applications instead of polyvinylchloride, polyurethane or polyethylene. However, PP as linear polymer exhibits low melt strength. One of the effective approaches to achieve high melt strength is to add chain branches onto backbone species using gamma radiation. Branching and grafting result from the macroradicals combinations during irradiation process. Crosslinking and main chain scission in the polymer structure are also obtained during this process. In this paper the gamma radiation technique was used to induce chemical changes in polypropylene/polybutene blends with an acetylene atmosphere. Acetylene was injected into polyethylene bags with polypropylene/polybutene blends. These samples were irradiated with a 60Co source from Embrarad, at doses of 12,5 and 20 kGy. The crosslinking of polymer was studied by measuring gel content and changes in the rheological properties of theses samples were observed as a function of melt strength and drawability obtained with a Rheotens apparatus and of melt index measurements. The polypropylene/polybutene blends showed a remarkable increase at drawability. (author)

315

The effect of electrostatic force on air filtration by polypropylene filter media  

International Nuclear Information System (INIS)

In this paper, the effect of irradiation with 60Co on the efficiency and strength of the polypropylene filter media is mainly researched. The charge density of polypropylene fibre is evaluated by radiation discharge method. Based on isolated cylinder model, the efficiency of the polypropylene filter media, which takes account of the effect of impaction, interception, diffusion and electrostatic, is calculated. A better agreement between theoretical analysis and experimental results is obtained. The results indicate that electrostatic force is the most important factor in solid aerosol filtration of the polypropylene filter media

316

The role of micrometric wollastonite particles on stress whitening behavior of polypropylene composites  

International Nuclear Information System (INIS)

The micromechanism and susceptibility to stress whitening during tensile straining of micrometric wollastonite mineral-reinforced polypropylenes is studied by electron microscopy and compared with unreinforced neat polypropylenes. Mineral-reinforced polypropylene composite exhibit significantly reduced susceptibility to stress whitening, and are characterized by lower gray level in the plastically deformed stress whitened zone. This behavior is attributed to the effective reinforcement of polypropylene by wollastonite that acts in concert increasing the tensile modulus of the composite and restricts plastic deformation of the matrix. The increase in tensile modulus is explained in terms of a three-phase model involving matrix, particle, and interface zone. Furthermore, isothermal crystallization indicated that the reinforcement mineral increases the rate of nucleation with consequent increase in % bulk crystallinity. The reinforcement of polypropylene alters the primary micromechanism of stress whitening from deformation bands/crazing in neat polypropylenes to wedge/ridge-tearing in mineral-reinforced polypropylene composites. The final fracture in reinforced polypropylene occurs by a mixed mode consisting of fibrillation and brittle mode, while crazing-tearing and brittle deformation are fracture modes for neat polypropylene

317

Stabilization of polypropylene, polypropylene blends with poly (styrene-b-(ethylene-co-butylene)-b-styrene) under irradiation: A comparative investigation  

International Nuclear Information System (INIS)

The aim of this paper is to investigate the stabilization of polypropylene in the poly (styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)/polypropylene (PP) blends under irradiation with respect to PP. The PP films, SEBS/PP films were subjected to electron beam irradiation and characterized by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and dynamic mechanical thermal analysis (DMTA). It demonstrated that upon irradiation, the molecular weight of PP had a pronounced decrease due to the major chain scission, and the minor chain cross-linking or chain branching occurred at the higher irradiation dose. Stabilization of PP was improved in the presence of SEBS, exhibiting an enhanced irradiation resistance.

318

Uterine artery suture: a preventive approach for pernicious placenta previa.  

Science.gov (United States)

Pernicious placenta previa is an obstetric complication that results in a crisis situation for many patients. Most existing options deal with the problems after delivery leading to unfavorable outcomes. To circumvent this situation, a few preventive simple surgical options have been discussed in this paper. The highlight of the approach is the application of ascending uterine artery suture that drastically reduced the amount of bleeding as compared to that observed in regular surgeries. Combined with the placenta accrete location, wedge resection and 'patch' homeostasis of the serous membrane, the surgical modifications adopted effectively reduced the need for hysterectomy thus preserving the fertility of the patients for the future. Since fetuses were safely removed within 1-2 min, the Apgar scores of the neonates were also largely unaffected. PMID:23949849

Du, Xiaodong; Xie, Xiaoe; Wang, Yi

2014-03-01

319

Application analysis on different suture of scleral flap in trabeculectomy  

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Full Text Available AIM: To research the application of scleral flap suture in trabeculectomy. METHODS: Totally 114 primary angle-closure glaucoma patients, aged from 36-72 years old, were selected as the objects, and randomly divided into research group and control group. The two groups received different administration methods. Traditional sewing method of sclera flap was used in research group and improved sewing method of sclera flap was used in control group. RESULTS: There was statistical differences between postoperative intraocular pressure of the patients in the observation group and the control group after 1d; 2wk; 1, 3mo(PPP>0.05.CONCLUSION: It is safe and effective that the improved sewing method of sclera flap for trabeculectomy of acute angle-closure glaucoma, and it is a better method to avoid the occurrence of shallow anterior chamber than the traditional sewing method in the early stage after operation.

Ning Liu

2014-05-01

320

Effects of maleated polypropylene on the morphology, thermal and mechanical properties of short carbon fiber reinforced polypropylene composites  

International Nuclear Information System (INIS)

Highlights: ? Carbon fibers (CFs) are the most widely used advanced reinforcing fiber materials. ? Improvement of adhesion between polypropylene (PP) matrix and CF were aimed. ? PP matrix was modified by addition of maleic anhydride grafted PP (PP-g-MAH). ? Mechanical properties of the composites were improved by PP-g-MAH compatibilizer. ? Modification of matrix with PP-g-MAH was improved the interfacial adhesion. -- Abstract: The aim of this study was to determine the effect of the maleic anhydride grafted polypropylene (PP-g-MAH) on the properties of short carbon fiber (CF) reinforced polypropylene (PP) composites. The composites were prepared by melt blending and injection molding techniques at different percentages of CF. Tensile tests, hardness, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) were performed to characterize the physical and morphological properties of the prepared composites. It was observed from SEM photographs that modification with PP-g-MAH improved the interfacial adhesion between the carbon fibers and PP matrix. The ultimate tensile strength, hardness and modulus values of modified PP composites were higher compared to the values of CF reinforced PP composites. Melting temperature of all composites was not changed significantly with increasing CF content; however degree of crystallinity values were decreased with the increasing CF content level.

 
 
 
 
321

Radiological assessment of skull base changes in children with syndromic craniosynostosis: role of ''minor'' sutures  

International Nuclear Information System (INIS)

This study aims to identify the premature synostosis of ''major'' and ''minor'' sutures of the four ''sutural arches'' of the skull and to perform a morphometric analysis in children with syndromic craniosynostosis in order to evaluate changes in the skull base linked with premature suture synostosis. We reviewed multiplanar high-resolution CT images, implemented with 3D reconstructions, from 18 patients with complex syndromic craniosynostosis and compared them with 18 age-matched healthy subjects. We assessed the calvarial sutures and their extension to the skull base, and then we correlated specific types of synostosis with the size, shape and symmetry of the cranial fossae. We found a marked asymmetry of the skull base growth in all patients. The synostotic involvement around the coronal ring caused a reduction in the growth of the anterior and middle fossae. The size of the posterior cranial fossa was related not only to ''major'' but also to ''minor'' suture synostosis of the lambdoid and parieto-squamosal arches. Changes in the skull base and craniofacial axis symmetry are due to structural and functional relationships between ''major'' and ''minor'' skull sutures, suggesting a structural and functional relationship between the neurocranium and basicranium. The early recognition of prematurely closed skull base sutures may help clinicians and neurosurgeons to establish correct therapeutic approaches. (orig.)

322

Development of silver nano-coatings on silk sutures as a novel approach against surgical infections.  

Science.gov (United States)

The infections give rise to a range of clinical problems and prolong hospitalization with increased healthcare costs. Moreover, persistent infections exasperate the problem of antibiotic resistance. The aim of this study was the development of effective and low-cost antibacterial silver coatings on surgical sutures by adopting an innovative photochemical deposition process to prevent early contamination of surgical wounds. The silver deposition technology adopted in this work is an innovative process based on the in situ photoreduction of a silver solution. The samples were dipped in the silver solution and then exposed to UV radiation in order to induce the synthesis of silver clusters on the surface of the suture. The homogeneous distribution of silver particles on the surface and on the cross-section of the treated sutures was demonstrated. All the antibacterial studies clearly demonstrated that the use of novel silver treated sutures could represent clinical advantages in terms of the prevention of surgical infections against bacterial colonization. The silver coating deposited on the sutures demonstrated no cytotoxic effect on a selected cell population. The results obtained suggested that the antibacterial silver-coated sutures developed in this work could represent an interesting alternative to conventional sutures, with evident advantages in terms of prevention of the surgical infections and on the health costs. In addiction, very low concentrations of silver significantly inhibited the microbial load, without affecting the cell viability. PMID:24997984

De Simone, S; Gallo, A L; Paladini, F; Sannino, A; Pollini, M

2014-09-01

323

Anatomy-Based navigation for ventriculostomy: Nasion-coronal suture distance measurement  

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Full Text Available Objective: In this study we aimed to determine a landmark that can be measured through the skin with nasal mid-point (bregma to coronal suture, and additionally an average value was calculated. We report, to our knowledge, the distance between the nasion-coronal sutures is reported for the first time in Turkish population. Methods: The study included 30 craniums and 30 frontal bones. Each skull from midline nasal suture to coronal suture curved up at the distance was measured with tape measure. Results: Mean values were determined. Nasal suture between coronal suture distance average 12,2 cm (min10,3 cm, up to 13,5 cm were detected. Conclusion: Nasal suture is an easily palpable area through the skin. A small incision is carried down through skin to bone at the spot 12 cm back from the nasion 3 cm lateral to the midline for ventricular drainage operation. This data provide practical information for neurosurgeon and is available everywhere. J Clin Exp Invest 2014; 5 (3: 368-370

Mevci Özdemir

2014-09-01

324

Healing time of incision infection after hepatobiliary surgery treated by needle-free incision suture closure  

Science.gov (United States)

AIM: To compare the effectiveness of needle-free incision suture closure with butterfly tape and traditional secondary suturing techniques in treating incision infection. METHODS: Two hundred and twenty-three patients with incision infection following hepatobiliary surgery at a tertiary hospital were randomly divided into three groups: 90 patients were closed by needle-free incision suture closure, which gradually closed the incision wound when drainage from incision infection was visibly decreased and healthy granulation tissues had grown; 79 patients were closed by butterfly bandage; another 54 patients were closed by traditional secondary suturing technique. Healing time of incision infection was calculated from the beginning of dressing change to the healing of the incision. RESULTS: Healing time in the needle-free incision suture closure group (24.2 ± 7.2 d) was significantly shorter than that in the butterfly bandage group (33.3 ± 11.2 d) and the traditional secondary suturing group (36.2 ± 15.3 d) (P 0.05). CONCLUSION: Needle-free incision suture closure could gradually close the infection wound at the same time of drainage and dressing change, thereby shortening the healing time.

Ma, Wen-Jie; Zhou, Yong; Mao, Hui; Xu, Rui-Hua; Shrestha, Anuj; Li, Fu-Yu; Lorance, Alex; Yang, Qin; Zhang, Yong-Qiong; Jiang, Ting; Feng, Huan; Zhang, Wei; Cheng, Nan-Sheng

2014-01-01

325

Effectiveness of ultrasonographic evaluation of the cranial sutures in children with suspected craniosynostosis  

Energy Technology Data Exchange (ETDEWEB)

Computed tomography (CT) is the 'gold standard' for evaluation of the cranial sutures. While prenatal cranial suture evaluation with ultrasound (US) is common, US has not been established as a postnatal screening tool. We evaluated the effectiveness of US for diagnosis of craniosynostosis (CS). During 2006, 24 infants with questionable CS were assessed with US of the sagittal, metopic, and bilateral coronal and lambdoid sutures. US findings and clinical records were reviewed retrospectively. Sixteen boys and eight girls (ages 1-11 months, mean 4.3) underwent US. The correct diagnosis was provided in 23 (95%), with equivocal findings in one patient. Cranial sutures appeared normal in 15 infants, who had normal clinical presentation at mean 5.8 months follow-up; CT confirmation was obtained in two. In eight children, US identified premature closure of one or more cranial sutures. Three-dimensional CT was performed as a preparation for surgery in four, with classical CS findings. In one case with inconclusive US findings, CT showed narrow but open sutures. Sonographic examination of cranial sutures may serve as a first imaging tool for evaluation of craniosynostosis. CT may be reserved for children with abnormal or equivocal ultrasound and for preoperative planning. (orig.)

Simanovsky, Natalia; Hiller, Nurith; Koplewitz, Benjamin; Rozovsky, Katya [Hadassah Hebrew University Medical Center, Department of Medical Imaging, Mount, Scopus, P.O. Box 24035, Jerusalem (Israel)

2009-03-15

326

Comparison of polydioxanone (PDS and polyamid (nylon sutures complications in abdominal midline repair (laparotomy surgery  

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Full Text Available Background and purpose: Despite progresss in the techniques of surgery, there is still a lot of controversy about selection of the best technique and suture material. Many post operation complications such as infection, wound dehiscence, pain and sinus formation are related to the type of the suture used. In this study we compared the complications due to the absorbent suture (PDS with a non absorbent suture (nylon in laparotomy operation.Materials and Methods: This clinical trial was performed on 120 patients referring to Imam Khomeini hospital, Sari, 2003-2005 for laparotomy. They were randomly divided in tow groups of equal number. The incision was repaired with PDS sutures in case and with nylon suture in control group. All patients under study were followed up for one year. Data about chronic pain,wound dehiscence, infection, hernia and sinus formation were recorded and analyzed using SPSS software and Chi- square test.Results: In this study 120 patients (60 in case and 60 in control groups were enrolled. After laparotomy, the incidence of chronic pain and sinus formation in case group was significantly less than the control group. There were no significant differences between the rate of infection, hernia and wound dehiscence in the two groups.Conclusion: No significant differences in the rate of infection, hernia and wound dehiscence between two types of suture materials were observed. However, application of PDS leads to less pain and sinus formation. Therefore, it can be a better choice in surgical incisions.

F.Eshghi

2006-01-01

327

Immunostimulatory sutures that treat local disease recurrence following primary tumor resection  

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Neuroblastoma is a common childhood cancer that often results in progressive minimal residual disease after primary tumor resection. Cytosine-phosphorothioate-guanine oligonucleotides (CpG ODN) have been reported to induce potent anti-tumor immune responses. In this communication, we report on the development of a CpG ODN-loaded suture that can close up the wound following tumor excision and provide sustained localized delivery of CpG ODN to treat local disease recurrence. The suture was prepared by melt extruding a mixture of polylactic acid-co-glycolic acid (PLGA 75:25 0.47 dL g{sup -1}) pellets and CpG ODN 1826. Scanning electron microscopy images showed that the sutures were free of defects and cracks. UV spectrophotometry measurements at 260 nm showed that sutures provide sustained release of CpG ODN over 35 days. Syngeneic female A/J mice were inoculated subcutaneously with 1 x 10{sup 6} Neuro-2a murine neuroblastoma wild-type cells and tumors were grown between 5 to 10 mm before the tumors were excised. Wounds from the tumor resection were closed using CpG ODN-loaded sutures and/or polyglycolic acid Vicryl suture. Suppression of neuroblastoma recurrence and mouse survival were significantly higher in mice where wounds were closed using the CpG ODN-loaded sutures relative to all other groups. (communication)

Intra, Janjira; Zhang Xueqing; Salem, Aliasger K [Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242 (United States); Williams, Robin L; Zhu Xiaoyan [Department of Surgery, Roy J and Lucille Carver College of Medicine, University of Iowa, Iowa City, IA 52242 (United States); Sandler, Anthony D, E-mail: aliasger-salem@uiowa.edu [Department of Surgery and Center for Cancer and Immunology Research, Children' s National Medical Center, Washington DC 20010 (United States)

2011-02-15

328

Effectiveness of ultrasonographic evaluation of the cranial sutures in children with suspected craniosynostosis  

International Nuclear Information System (INIS)

Computed tomography (CT) is the 'gold standard' for evaluation of the cranial sutures. While prenatal cranial suture evaluation with ultrasound (US) is common, US has not been established as a postnatal screening tool. We evaluated the effectiveness of US for diagnosis of craniosynostosis (CS). During 2006, 24 infants with questionable CS were assessed with US of the sagittal, metopic, and bilateral coronal and lambdoid sutures. US findings and clinical records were reviewed retrospectively. Sixteen boys and eight girls (ages 1-11 months, mean 4.3) underwent US. The correct diagnosis was provided in 23 (95%), with equivocal findings in one patient. Cranial sutures appeared normal in 15 infants, who had normal clinical presentation at mean 5.8 months follow-up; CT confirmation was obtained in two. In eight children, US identified premature closure of one or more cranial sutures. Three-dimensional CT was performed as a preparation for surgery in four, with classical CS findings. In one case with inconclusive US findings, CT showed narrow but open sutures. Sonographic examination of cranial sutures may serve as a first imaging tool for evaluation of craniosynostosis. CT may be reserved for children with abnormal or equivocal ultrasound and for preoperative planning. (orig.)

329

Mechanical Properties of Cranial Bones and Sutures in 1–2-Year-Old Infants  

Science.gov (United States)

Background The mechanical properties of 1–2-year-old pediatric cranial bones and sutures and their influential factors were studied to better understand how the pediatric calvarium reacts to loading. Material/Methods Cranial bone and suture specimens were extracted from seven fresh-frozen human infant cadavers (1.5±0.5 years old). Eight specimens were obtained from each subject: two frontal bones, two parietal bones, two sagittal suture samples, and two coronal suture samples. The specimens were tested in a three-point bend setup at 1.5 mm/s. The mechanical properties, such as ultimate stress, elastic modulus, and ultimate strain, were calculated for each specimen. Results The ultimate stress and elastic modulus of the frontal bone were higher than those of the parietal bone (Pelastic modulus, or ultimate strain (P>0.05). The ultimate stress and elastic modulus of the frontal and parietal bones were higher than those of the sagittal and coronal sutures (Pelastic modulus, or ultimate strain between the sagittal and coronal sutures. However, there were significant differences in ultimate stress, elastic modulus, and ultimate strain between the frontal and parietal bones as well as between the cranial bones and sutures. PMID:25279966

Wang, Jiawen; Zou, Donghua; Li, Zhengdong; Huang, Ping; Li, Dongri; Shao, Yu; Wang, Huijun; Chen, Yijiu

2014-01-01

330

Experimental studies on the influence of irradiation (60Co) on wound healing of colonic suture  

International Nuclear Information System (INIS)

Effects of preoperative 60Co irradiation on wound healing of colonic suture in adult dogs of mixed breed were discussed. Wound healing 7 days after colonic suture was compared among dogs which received colonic suture immediately, or 3 days, or 7 days after the 60Co irradiation. As a result, there was not a big difference in their wound healing among these dogs, and disorders of wound healing were not found. Bursting pressure at sutured sites was always lower in irradiated dogs than controls. Recovery of the bursting pressure was 2 days slower in irradiated dogs than non-irradiated dogs for 7 days after the suture. Bursting pressure was the lowest on the 3rd day after the suture in both groups. As to fine changes in irradiated dogs, appearance of recommunicating phenomena in blood vessels, delay of a decrease in avascular regions, delay of granulation, and hypertrophy of vascular walls seemed to be influenced by 60Co irradiation, but there was not a big difference in these results between irradiated and non-irradiated dogs. An increase in postoperative concentration of hydroproline tended to be little lower in irradiated dogs than controls, which seemed to be influenced by the 60Co irradiation. This result was also suggested from delay of granulation and remaining inflammations. Effects of 60Co irradiation on wound healing of colonic suture seemed to be slight generally, because ruptured suture scarecely occurred icause ruptured suture scarecely occurred in the irradiated dogs. When doses used in this experiment were calculated roughly by Ellis's method, irradiation of 60Co seemed not to influence seriously wound healing if the total of 2,000 to 2,500 rad was irradiated in 8 to 10 doses to human colon. (Tsunoda, M.)

331

Sutura intestinal monoplano extramucosa en dos hemisurget en pacientes con operaciones abdominales / Single layer intestinal extramucosal suturing using two semi-continuous sutures in patients with abdominal surgery  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish Objetivo: comparar el empleo de la sutura intestinal monoplano extramucosa en dos hemisurget con la sutura en dos planos, en pacientes con operaciones abdominales. Métodos: se realizó un estudio observacional-analítico de tipo prospectivo, de evaluación de tecnología quirúrgica, controlado, aleatori [...] zado y a simple ciegas, en 126 pacientes mayores de 15 años de edad, de ambos sexos. En 76 se empleó el método monoplano extramucosa en dos hemisurget y en 50 pacientes se utilizó el método de sutura intestinal en dos planos. Se tuvo en cuenta la frecuencia y el tipo de las complicaciones y su relación con el método de sutura empleado, así como la influencia en el tiempo quirúrgico y el tiempo de estadía hospitalaria. Resultados: con el método monoplano extramucosa en dos hemisurget, solo 13 pacientes sufrieron algún tipo de complicación; 64 pacientes (84,2 %) fueron intervenidos en un tiempo menor a las 2 h y el 80,3 % tuvo una estadía hospitalaria menor de 7 días. Las complicaciones más frecuentes en ambos grupos fueron la infección del sitito operatorio, las fístulas estercoráceas y la dehiscencia parcial de la sutura. La sutura intestinal monoplano extramucosa en dos hemisurget presentó menor frecuencia de complicaciones y una disminución considerable en el tiempo quirúrgico y la estadía hospitalaria. Conclusiones: la sutura intestinal monoplano en dos hemisurget resulta el método de elección para la sutura intestinal. Abstract in english Objective: compare the use of single layer intestinal extramucosal suturing using two semi-continuous sutures versus two-layer suturing in patients with abdominal surgery. Methods: a controlled randomized single-blind observational-analytical prospective surgical technique evaluation study was condu [...] cted with 126 patients of both sexes aged over 15. The single-layer extramucosal method using two semi-continuous sutures was used in 76 patients, and the two-layer intestinal suturing method in 50. Account was taken of the frequency and type of complications, and their relation to the suturing method used, as well as the influence upon surgical time and the length of hospital stay. Results: with the single layer extramucosal method using two semi-continuous sutures only 13 patients had complications of any sort; surgical time was under 2 h in 64 patients (84.2 %), and the length of hospital stay was under 7 days in 80.3 %. The most common complications in both groups were surgical site infection, stercoraceous fistulas and partial suture dehiscence. Single layer intestinal extramucosal suturing using two semi-continuous sutures showed a lower rate of complications and a considerable decrease in surgical time and length of hospital stay. Conclusions: single layer intestinal suturing using two semi-continuous sutures is the method of choice for intestinal suturing.

Yury, Valle Lara; Vivian, Rodríguez Tápanes.

2012-06-01

332

Modification of conductive properties of (10, 0) zigzag single-walled carbon nanotubes (SWCNT) by alkali metals absorption  

Science.gov (United States)

We have investigated the electronic and structural properties of (10, 0) zigzag single-walled carbon nanotubes (SWCNT) which have adsorbed different alkali metals (X: Li, Na, K, and Cs) and the hydrogen atom by using Density Functional Theory (DFT). It was discovered that among the alkali elements, Li atoms form the strongest bond with SWCNT. In addition, a significant shift was observed in the electronic state of alkali-adsorbed SWCNT compared to pristine SWCNT. Finally, it was proposed that due to showing excellent electronic structure, these modified nanotubes can be applied in new electronic devices, such as transistors, and field emission displays.

Hamadanian, Masood; Tavangar, Zahra; Noori, Banafsheh

2014-11-01

333

Microsurgical reparation of facial nerve of Wistar rat with suture – Part 1  

Directory of Open Access Journals (Sweden)

Full Text Available The right-side facial nerve of 20 Wistar rats was trans-sectioned and,immediately treated with three plain epineural suture stitches. Analysisof the results was based on histopathological aspects of the anastomoticarea. It was noticed that the presence of the suture material was responsible for the poor directioning of the nerve fibers and the neuroma formation in the anastomosis area, due to the collision of the regenerating nerve fibers with the granulomatous reaction to the suture string. Wallerian degeneration and proliferation of fibrous tissue were noticed.

João Armando BRANCHER

2005-05-01

334

Making straight suture needles a little safer: a technique to keep fingers from harm's way.  

Science.gov (United States)

Straight suture needles are commonly employed to secure arterial and venous catheters to the skin. These needles have been demonstrated to be more dangerous than curved or blunt suture needles, with a higher rate of injury for health care workers. This article describes a technique for using the straight needle that may reduce the chances of injury. By utilizing the plastic needle sheath present in most central venous line kits as a "thimble," counter pressure and skin puncture may be achieved without bringing the fingers near the sharp end of the suture. PMID:18282537

Nelson, Bret P

2008-02-01

335

Knot integrity of coated synthetic absorbable sutures used for extraocular muscle surgery in a rabbit model.  

Science.gov (United States)

Knot integrity of a new coated polyglycolic acid suture (Dexon Plus) was compared to that using uncoated polyglycolic acid (Dexon-S) and coated polyglactin-910 (Vicryl) for extraocular muscle recessions in rabbits. Knot integrity was found to be virtually identical using 6-0 sutures of any of these materials. Top throws of 5-0 coated Dexon or 5-0 coated Vicryl had a tendency to loosen in a few cases, though this was eliminated in later operations by more careful tightening of knots and avoidance of cutting suture ends to a length less than 2 mm. Subjectively observed differences in "tissue drag" were insignificant in this model. PMID:6279814

Estes, R L; Sugar, A

1982-01-01

336

Faraday rotation of the supernova remnant G296.5+10.0: Evidence for a Magnetized Progenitor Wind  

CERN Document Server

We present spectropolarimetric radio images of the supernova remnant (SNR) G296.5+10.0 at frequencies near 1.4 GHz, observed with the Australia Telescope Compact Array. By applying rotation measure (RM) synthesis to the data, a pixel-by-pixel map of Faraday rotation has been produced for the entire remnant. We find G296.5+10.0 to have a highly ordered RM structure, with mainly positive RMs (mean RM of +28 rad/m**2) on the eastern side and negative RMs (mean RM of -14 rad/m**2) on the western side, indicating a magnetic field which is directed away from us on one side and toward us on the other. We consider several possible mechanisms for creating the observed RM pattern. Neither Faraday rotation in foreground interstellar gas nor in a homogeneous ambient medium swept up by the SNR shell can easily explain the magnitude and sign of the observed RM pattern. Instead, we propose that the observed RMs are the imprint of an azimuthal magnetic field in the stellar wind of the progenitor star. Specifically, we calcul...

Harvey-Smith, L; Kothes, R; Townsend, R; Heald, G H; Ng, C -Y; Green, A J

2010-01-01

337

Preliminary calculations of coolant flow in a SCWR Fuel assembly with the code ANSYS CFX 10.0  

International Nuclear Information System (INIS)

For the design of Supercritical-Water Cooled Reactors (SCWRs) it is important to get know the thermal phenomena and the flow field in the different fuel assembly concepts. The ANSYS-CFX-10.0 code, a commercial computational fluid dynamics code has been used for investigating this field. The specific feature of the supercritical heat transfer is that the material properties change dramatically in a specific temperature range around the so-called pseudo-critical temperature. Because of this specific feature, we had to validate the ANSYS-CFX-10.0 code to see if it is capable for handling the heat transfer phenomena for supercritical state fluids. The calculations of a 2950 mm long straight pipe model were compared with measurement data and the prediction of the Swenson correlation recommended by international literature. The validation has been successful and the study could keep on. Three different sub-channel models were developed based on the European SCWR fuel assembly concept. Several calculations were performed with these sub-channel models for different boundary conditions. The calculations performed have showed problems with imbalance values. This investigation has showed the difficulty of the calculation of heat transfer processes when the temperature is around the value of the pseudo-critical temperature

338

Pubovaginal sling with a low-cost polypropylene mesh  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english OBJECTIVE: The aim of this study was to present the results of pubovaginal sling with a low-cost polypropylene mesh in the treatment of stress urinary incontinence MATERIALS AND METHODS: 118 women diagnosed with stress urinary incontinence (SUI) due to urethral hypermobility or intrinsic sphincteric [...] deficiency, treated with pubovaginal sling (PVS) with a low-cost polypropylene mesh confectioned by the surgeon, were analyzed. All patients had a basic evaluation that included a medical history, physical examination, stress tests and urodynamic investigation RESULTS: The average follow up was of 42 months. Urethral hypermobility was observed in 67% of the cases. The process was carried out on an outpatient basis on 67 patients. Intra-operative complications included 4 vesical injuries, treated with catheterization for 3 days. There were 13 early complications, of which 8 were urinary retentions treated with vesical drainage for 1 to 3 weeks and 3 vaginal extrusions of the mesh treated with covering of the sections with mucous membrane. There was a need for 6 urethrolysis in patients who presented irritative and postoperative obstructive symptoms; 81.3% of the patients were considered cured, while 9.3% had significant improvement. Three initially unsuccessful cases required sling reconfiguration. All cases were eventually cured CONCLUSION: The construction of a pubovaginal sling using a low-cost polypropylene mesh is a safe and effective technique for the relief of SUI. It should be considered an alternative, especially for patients in public health systems with low financial resources.

Fransber R., Rodrigues; Romulo, Maroccolo Filho; Roberto R., Maroccolo; Lucio C., Paiva; Fernando A., Diaz; Eduardo C., Ribeiro.

339

Conversion of atactic polypropylene waste to fuel oil. Final report  

Energy Technology Data Exchange (ETDEWEB)

A stable, convenient thermal pyrolysis process was demonstrated on a large scale pilot plant. The process successfully converted high viscosity copolymer atactic polypropylene to predominantly liquid fuels which could be burned in commercial burners. Energy yield of the process was very high - in excess of 93% including gas phase heating value. Design and operating data were obtained to permit design of a commercial size atactic conversion plant. Atactic polypropylene can be cracked at temperatures around 850/sup 0/F and residence time of 5 minutes. The viscosity of the cracked product increases with decrease in time/temperature. A majority of the pyrolysis was carried out at a pressure of 50 psig. Thermal cracking of atactic polypropylene is seen to result in sigificant coke formation (0.4% to 0.8% on a weight of feed basis) although the coke levels were of an order of magnitude lower than those obtained during catalytic cracking. The discrepancy between batch and continuous test data can be atrributed to lowered heat transfer and diffusion rates. Oxidative pyrolysis is not seen as a viable commercial alternative due to a significant amount of water formation. However, introduction of controlled quantities of oxygen at lower temperatures to affect change in feedstock viscosity could be considered. It is essential to have a complete characterization of the polymer composition and structure in order to obtain useful and duplicable data because the pyrolysis products and probably the pyrolysis kinetics are affected by introduction of abnormalities into the polymer structure during polymerization. The polymer products from continuous testing contained an olefinic content of 80% or higher. This suggests that the pyrolysis products be investigated for use as olefinic raw materials. Catalytic cracking does not seem to result in any advantage over the Thermal Cracking process in terms of reaction rates or temperature of operation.

Bhatia, J.

1981-04-01

340

GC-MS OF POLYETHYLENE AND POLYPROPYLENE THERMAL CRACKING PRODUCTS  

Directory of Open Access Journals (Sweden)

Full Text Available Low-density polyethylene and polypropylene were thermally decomposed individually in a batch reactor at 450°C as a recycling route from the aspect of the production of petrochemical feedstock. The resulting transformation liquid products were analysed by high resolution gas chromatographic-mass spectrometric analysis. More detailed separation of polyalkenes splitting compounds was achieved using high resolution GC (efficiencies up to 490 000 plates than before. The GC-MS as well as the dependence of homomorphy factors and isopropyl group increments on the number of carbon atoms of alk-1-enes, alk-2-enes, alka-?,?-dienes and alkanes were used for identification of separated analytes.Thermal cracking of LDPE products in the range C5-C23 were characterized by quintets of peaks in the chromatogram which were assigned to n-alkanes, alk-1-enes, (E-alk-2-enes, (Z-alk-2-enes and alka-?,?-dienes with average quantitative ratio 1 : 1.2 : 0.07 : 0.05 : 0.08. In fraction up to n-C8 140 GC peaks were separated and identified, including around 30 acyclic octenes.In contrast to the polyethylene thermal cracking which yields products with straight-chain hydrocarbon structure, polypropylene cracking is characterized by the formation of compounds with branched and high prevailingly unsaturated hydrocarbon structure. The pretention of this analytical problem lies in stereoisomerism and corresponding multicomponentity of branched alkenes, alkadienes and alkanes in a broad range of carbon atoms number as main decomposition products of polypropylene. In the liquid fraction up to n-C8 84 peaks including around 40 acyclic octenes were identified. Other 149 GC peaks were analysed in the C9-C25 fraction with quantitative ratio of alkane : alkene : alkadiene equal to 1 : 17 : 4. High resolution GC allowed more detailed and more reliable analysis of multicomponent polyalkenes cracking products.

Martin Bajus

2006-03-01

 
 
 
 
341

Tribological properties of polypropylene composites with carbon nanotubes and sepiolite.  

Science.gov (United States)

Carbon nanotubes (CNTs) and sepiolite (SEP) were modified in order to improve their compatibility with the polypropylene (PP) matrix. Carboxylic groups were introduced into the CNTs through an oxidative treatment and aliphatic chains were incorporated on SEP by ion exchange of a cationic surfactant. Maleic anhydride grafted polypropylene (PPgMA) was mixed with neat PP to introduce polar groups into the polymer matrix. Composites including modified and non-modified fillers were prepared by melt extrusion. Dispersion and interaction of the CNTs with the PP and PPgMA matrices were evaluated by Raman spectroscopy while a focused ion beam/scanning electron microscopy (FIB/SEM) was used for SEP containing composites. Scratch resistance, microhardness, dynamic friction and wear were determined. Raman spectroscopy shows that the introduction of polar groups into PP matrices has a positive effect on the dispersion of modified CNTs. FIB/SEM results show that the modification of SEP improves its dispersion in the polypropylene matrix; filler clusters found in the PPgMA matrix are much times smaller than those in the neat PP. Despite of SEP agglomerates in the composites, a good interaction between both phases is seen; SEP particles are fully coated and embedded inside the PP matrix. The 'lack of cooperation' between unmodified PP and its fillers results in nanocomposites with larger residual depths; by contrast, PPgMA does 'cooperate' with its fillers so that the nanocomposites in scratch resistance testing have smaller residual depths R(h) than the neat PPgMA. Addition of the fillers to PPgMA also increases the hardness. As for wear rates, some our fillers provide higher and some lower wear rates than PP. PMID:24757963

Orozco, Victor H; Vargas, Andres F; Brostow, Witold; Datashvili, Tea; López, Betty L; Mei, Kevin; Su, Lisa

2014-07-01

342

Pubovaginal sling with a low-cost polypropylene mesh  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english OBJECTIVE: The aim of this study was to present the results of pubovaginal sling with a low-cost polypropylene mesh in the treatment of stress urinary incontinence MATERIALS AND METHODS: 118 women diagnosed with stress urinary incontinence (SUI) due to urethral hypermobility or intrinsic sphincteric [...] deficiency, treated with pubovaginal sling (PVS) with a low-cost polypropylene mesh confectioned by the surgeon, were analyzed. All patients had a basic evaluation that included a medical history, physical examination, stress tests and urodynamic investigation RESULTS: The average follow up was of 42 months. Urethral hypermobility was observed in 67% of the cases. The process was carried out on an outpatient basis on 67 patients. Intra-operative complications included 4 vesical injuries, treated with catheterization for 3 days. There were 13 early complications, of which 8 were urinary retentions treated with vesical drainage for 1 to 3 weeks and 3 vaginal extrusions of the mesh treated with covering of the sections with mucous membrane. There was a need for 6 urethrolysis in patients who presented irritative and postoperative obstructive symptoms; 81.3% of the patients were considered cured, while 9.3% had significant improvement. Three initially unsuccessful cases required sling reconfiguration. All cases were eventually cured CONCLUSION: The construction of a pubovaginal sling using a low-cost polypropylene mesh is a safe and effective technique for the relief of SUI. It should be considered an alternative, especially for patients in public health systems with low financial resources.

Fransber R., Rodrigues; Romulo, Maroccolo Filho; Roberto R., Maroccolo; Lucio C., Paiva; Fernando A., Diaz; Eduardo C., Ribeiro.

2007-10-01

343

Radiation grafting of styrene and acrylic acid onto pre-irradiated polypropylene fabric  

International Nuclear Information System (INIS)

Grafting copolymerization of styrene and acrylic acid onto polypropylene fabric has been studied by using a pre-irradiation technique. The polypropylene fabric samples were irradiated by ?-ray and electron beam under the conditions of air and nitrogen gas. The effect of absorbed dose, monomer concentration in solvent, reaction temperature and reaction time on the degree of grafting were determined. The effects of metallic salts and sulphuric acid on the grafting yield of acrylic acid were also examined. The samples irradiated by electron beam gave a much higher degree of grafting than those by ?-ray when styrene was grafted to polypropylene fabric. However, the grafting yield of acrylic acid on polypropylene fabric in the condition of metallic salts and sulphuric acid showed the opposite results from the case of styrene. This effect was reasonably interpreted by assuming that the grafting is dominated by trapped radicals and peroxides in polypropylene. (author)

344

Physical and Mechanical Properties of Natural Fibers Filled Polypropylene Composites and Its Recycle  

Directory of Open Access Journals (Sweden)

Full Text Available This study discusses the influence of natural fiber type on the performance of polypropylene and its recycle. Composites consisting of polypropylene (PP and natural fiber from wood (Acacia mangium, water hyacinth (Eichornia crassipes, kenaf (Hibiscus cannabinus, banana (Musa paradisiaca and empty fruit bunch of oil palm (Elaeis guineensis were prepared by extrusion and compression process based on the ratio of 50:50% (w/w with the addition of 2.5% polypropylene modified with maleic anhydride (MAPP. The effect of fiber type on the composites was evaluated. Physical and mechanical properties were studied. The composite showed significantly different properties based on the fiber type. Kenaf filled composite showed high tensile strength, break strain and modulus of elasticity properties but least absorbed water. Banana fiber filled propylene composite is comparable with that of kenaf. In general, recycle polypropylene can replace virgin polypropylene since their natural fibers filled composites showed similar mechanical and physical properties.

Myrtha Karina

2007-01-01

345

Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The effect of incorporating (C2-C8) ethylene-octene elastomer on the mechanical properties and morphology of polypropylene copolymers has been investigated employing two types of PP copolymer, with and without nucleating agent. The results were compared to the ones presented by a commercial PP heter [...] ophase (reactor impact modified PP/EPR). The addition of the elastomer increases the toughness of the blends but reduces their stiffness. PP blends in the low elastomer content region (

Cybele, Lotti; Carlos A., Correa; Sebastião V., Canevarolo.

2000-04-01

346

Physical changes associated with gamma doses on Wood/ Polypropylene Composites  

Science.gov (United States)

The effect of gamma- radiation on the morphology, thermal behavior and mechanical properties of wood polypropylene composites has been investigated. Simultaneous thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been performed on WPC samples of (9.5 ± 0.1) mg. These samples were exposed to different gamma-dose in the range 10 to 100kGy. The results indicated that gamma radiation improves the mechanical properties while the thermal stability is decreased. With gamma radiation, the scanning electron microscopy (SEM) of the micrographs became smoother and we can notice an improvement of interaction between polymer and wood fibers.

Ndiaye, Diène; Tidjani, Adams

2014-08-01

347

Early Stage Crystallization in Isotactic Polypropylene: Influence of Nanofillers  

Science.gov (United States)

Formation of helices in isotactic polypropylene was studied using on-lattice, coarse-grained, Metropolis Monte Carlo simulations. Influence of polymer-particle interaction and particle size on polymer crystallization was studied by inserting isotropic particles into neat iPP melt. Results indicated that the surface of isotropic particle exerts a strong orientation effect on helices and their ordering. In addition, isotropic particle shows a length scale effect on the formation of long helical structures at low temperatures, i.e., below melting temperature.

Ozisik, Rahmi; Chen, Xiaofeng; Kumar, Sanat; Choi, Phillip

2008-03-01

348

Light weight polarized polypropylene foam for noise shielding  

Science.gov (United States)

The high levels of noise generated during launch can destroy sensitive equipment on space craft. Passive damping systems, like acoustic blankets, work to reduce the high frequency noise but do little to the low frequency noise (materials with a multiple loop feedback system will give a total damping effect that is adaptable over a wide band of low frequencies. This paper covers the manufacturing methods that were used to make polarized polypropylene foam, to test the foam for its polarized response and its noise shielding ability.

Zelfer, Travis J.; Warne, Derik S.; Korde, Umesh A.

2009-03-01

349

Polypropylene-polyethylene blends modified by gamma radiation  

International Nuclear Information System (INIS)

One way to obtain a better mechanical property of polypropylene and polyethylene is to increasing the number of polymer chains cross-linked by gamma radiation. After irradiation a network is formed as a result of various chemical reactions and the radicals formed are concentrated in the amorphous phase. With the objective to improve the mechanical properties of PP, blends with PE were prepared and irradiated in doses up to 500 kGy, in atmospheric ambient. The molecular characterization of the blends was made by infrared spectroscopy and the data showed an increase in rigidity and a unique behaviour in Izod impact resistance. (author)

350

Elastic properties of highly anisotropic thin poly(propylene) foams  

CERN Document Server

In this letter, elastic properties of highly anisotropic cellular poly(propylene) films are reported. The material shows peculiar elastic properties compared to other foams in the literature. The data is displayed as the relative Young's modulus $E^*/E_s$ versus relative density $\\rho^*/\\rho_s$. Almost all the data from the literature are located on the region $E^*/E_s=(\\rho^*/\\rho_s)^n$ with $1\\le n\\le6$. The introduced material on the other hand have lower relative Young's modulus at high relative densities, $n\\ge6$.

Tuncer, E; Tuncer, Enis; Wegener, Michael

2004-01-01

351

Post gamma-irradiation grafting of polypropylene film  

International Nuclear Information System (INIS)

The post ?-irradiation grafting of gaseous butadiene to isotactic polypropylene film has been continuously monitored by monomer uptake. Grafting is most efficient to prior annealed polymer in the temperature range 35 to 45 deg C. At higher temperatures, competition by radical termination leads to lower graft content. The effect of dose is small initially but increases markedly with conversion. For example after 30 hr at 45 deg C the rate is close to second order in dose. The results are compatible with a model for post irradiation grafting to semi-crystalline polymers developed from the literature. Some properties of the copolymer are described. (author)

352

Formation of silver nanoparticles on polypropylene microfibrous carriers  

Science.gov (United States)

Methods of physical and numerical experiments are used to investigate formation of quantum dissipative silver nanostructures on polypropylene microfibrous condensed-state carriers under two-stage activation by UV- and microwave radiation. For these two nanoprocessing stages, two different mechanisms of quantum activated silver nanoparticle relaxation are suggested, including dissipation of their energy into the polymeric matrix through the exciton femtosecond and phonon picosecond channels. A comparison of the results of mathematical modeling and physical experiments testifies to the adequacy of these models to the physical processes of self-assembly and self-organization of polymeric biomimetic fibrous material modified by silver nanoparticles.

Zhukovsky, M. S.; Lysak, I. A.; Lysak, G. V.; Vazhenin, S. V.; Malinovskaya, T. D.; Beznosjuk, S. A.

2011-12-01

353

Polypropylene/organoclay/SEBS nanocomposites with toughness-stiffness properties  

DEFF Research Database (Denmark)

Polypropylene nanocomposites with a different amount of styrene-ethylene-butylene-styrene block copolymer (SEBS)/clay were prepared via a melt mixing technique. To improve the dispersion of commercial organoclay (denoted as OMMT), various amounts of SEBS were incorporated. At a fixed content of OMMT, the mechanical properties were improved with increasing SEBS content. The obtained nanocomposites were characterized through X-ray diffraction (XRD), differential scanning calorimetry (DSC-TG) and mechanical tests. The thermal-morphological-mechanical properties were investigated. The nanomaterials presented an improved decomposition temperature, a small decrease in tensile strength, a higher Young's modulus and a spectacular increase of 300% in impact strength.

Sanporean (nee Potarniche), Catalina-Gabriela; Vuluga, Zina

2014-01-01

354

Fracture of ultrafine calcium carbonate/polypropylene composites  

Energy Technology Data Exchange (ETDEWEB)

The strength and fracture properties of a polypropylene filled with ultrafine calcium carbonate (0.07 micron) have been studied in the composition range of 0 to 40 percent by volume. Untreated and surface treated (with stearic acid and a titanate coupling agent) grades have been considered. The untreated filler caused a decrease of toughness, whereas a maximum, at about 10 percent, was observed for the treated filler. The fracture energy was analyzed in terms of the crack-pinning model. Due to the very small size of particles, the pinning contribution proved to be negligible. 30 references.

Levita, G.; Marchetti, A.; Lazzeri, A.

1989-02-01

355

High temperature pipeline coatings using polypropylene over fusion bonded epoxy  

Energy Technology Data Exchange (ETDEWEB)

The following is a discussion of test results and application techniques for high temperature pipe line coatings of polypropylene over fusion bonded epoxy. Recent tests to internal temperatures of 150 C (300 F) indicate these coatings, when applied properly, will perform well at these temperatures. Test results from several different tests are included. Repairs, field joints and bend coating with these type coatings are discussed. Problems during and after application are summarized. Use of well written specifications and experienced, dedicated inspectors add to the quality of the coating process. As industry moves to hotter and hotter production, these factors become even more critical in the pipeline coating process.

Norsworthy, R. [Tomar Systems, Inc., DeSoto, TX (United States)

1996-12-31

356

Timing of cranial suture closure in placental mammals: phylogenetic patterns, intraspecific variation, and comparison with marsupials.  

Science.gov (United States)

Used as markers of postnatal growth closure sequences of 22 ectocranial sutures and synchondroses were recorded in a sample of 1161 skulls belonging to 38 species from all major placental clades: Afrotheria, Xenarthra, Laurasiatheria and Euarchontoglires (Boreoeutheria). The maximum closure level, which is not significantly correlated to body mass, is higher in Afrotheria and Xenarthra than in Boreoeutheria. Only the basioccipito-basisphenoid and the basioccipito-exoccipital synchondroses close in all species sampled, the supraoccipito-exoccipital and the inter-parietal sutures do in most species. Parsimov retrieved more heterochronic shifts for Afrotheria and Xenarthra than for Boreoeutheria. The amount of intraspecific variation differs among the species sampled being high among xenarthran species and low among afrotherians. Specimens (162) representing 12 marsupial genera were also analysed. Placentals exhibit a larger number of suture closures than marsupials and in both groups the sutures at the base of the skull are the first to fuse starting with the basioccipito-exoccipital. PMID:24127274

Rager, Lisa; Hautier, Lionel; Forasiepi, Analía; Goswami, Anjali; Sánchez-Villagra, Marcelo R

2014-02-01

357

Vein patch angioplasty with non-penetrating titanium clips. Comparison to standard suture technique.  

Science.gov (United States)

Our purpose was to compare the Vascular Closure Staples (VCS) clips to a standard suture technique for vein patch angioplasty in a porcine model. Six female pigs underwent vein patch angioplasty of the common iliac arteries with either VCS clips or continuous suturing. The reconstructed vessels were evaluated macroscopically, angiographically and histologically after two months by re-operation. There was a non significant trend towards shorter reconstruction (6.5 +/- 1.8 min. for clips vs. 8.5 +/- 1.7 min. for sutures, p = 0.15) and clamp times when clips were used (8.4 +/- 1.5 min. vs. 10.1 +/- 1.3 min., p = 0.15). At re-operation all vessels were found patent without significant histological differences regarding the intimal reaction. VCS clips are a reliable alternative to sutures for vein patch angioplasty. PMID:20184062

Pikoulis, E; Rhee, P; Nishibe, T; Koronarchis, D; Leppäniemi, A; Karavokyros, I; Burris, D; Bakoyiannis, C; Fishback, N; Wherry, D; Rich, N

2009-01-01

358

Deformation and sedimentation along a developing terrane suture: Eastern Sunda forearc, Indonesia  

Science.gov (United States)

The collision of the eastern Sunda arc with northwest Australia has resulted in the development of a suture between the Sumba ridge and Sawu-Timor terrenes along a zone of intraforearc convergence. The developing suture varies from the low-angle Sawu thrust, with attendant mud diapirs in the Sumba basin, to high-angle reverse faults near a basement: high of the underthrust Sumba ridge terrane. Bottom currents, associated with the flow of Pacific Ocean deep water into the Indian Ocean, have eroded the terrenes and subsequently deposited the detritus in an assemblage of contourites along the suture. This study reveals the high structural variability of a terrane suture and the oceanographic influence on trie deposition of overlap assemblages.

Reed, Donald L.; Silver, Eli A.; Prasetyo, Hardi; Meyer, Audrey W.

1986-12-01

359

Bilateral squamosal suture synostosis: A rare form of isolated craniosynostosis in Crouzon syndrome  

Science.gov (United States)

Craniosynostosis is a pathologic condition which is characterized by the premature fusion of cranial sutures. It may occur alone or in association with other anomalies making up various syndromes. Crouzon syndrome is the most common craniosynostosis syndrome. Bicoronal sutures fusion is most commonly involved in Crouzon syndrome. There have only been a handful of cases of squamosal suture synostosis described in the surgery literature with the few ones described in Crouzon syndrome associated with other types of craniosynostosis. To the best of our knowledge, we are presenting the first case of isolated bilateral squamosal suture synostosis in a patient with Crouzon syndrome in a radiology journal with emphasis on its radiological appearance. PMID:25071892

Tandon, Yasmeen K; Rubin, Michael; Kahlifa, Mohamed; Doumit, Gaby; Naffaa, Lena

2014-01-01

360

Performance Assessment of Suture Type in Juvenile Chinook Salmon Surgically Implanted with Acoustic Transmitters.  

Science.gov (United States)

The objective of this study was to determine the best overall suture material to close incisions from the surgical implantation of Juvenile Salmon Acoustic Telemetry System (JSATS) acoustic microtransmitters in subyearling Chinook salmon Oncorhynchus tsha...

J. W. Boyd, K. A. Deters, K. M. Carter, R. S. Brown

2009-01-01

 
 
 
 
361

One stage vertical rectus muscle recession using adjustable sutures under local anaesthesia.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

AIMS: To assess the results of visual axis alignment following one stage adjustable suture surgery to correct vertical diplopia. METHOD: Eight patients with a mean age of 44.9 years (range 16-80 years) complaining of vertical diplopia underwent rectus muscle recession under local anaesthesia with intraoperative adjustment of sutures. Diplopia was secondary to superior oblique paresis in four patients, dysthyroid eye disease in two patients, superior rectus paresis in one patient, and one deve...

Rauz, S.; Govan, J. A.

1996-01-01

362

Treatment of thyroid ocular myopathy with adjustable and nonadjustable suture strabismus surgery.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Our results pooled with those of others demonstrate a statistically significant improvement in outcome when adjustable sutures are implemented in the treatment of thyroid ocular myopathy. To our knowledge, this degree of significance has not been reported previously. We believe the value of adjustable suture strabismus surgery lies mainly in the prevention of large undercorrections and overcorrections. However, one cannot guarantee fusion or long-term alignment stability, especially without p...

Kraus, D. J.; Bullock, J. D.

1993-01-01

363

B-Lynch suture technique to control postpartum hemorrhage in a patient with mullerian anomaly  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Congenital anomalies of the uterus may cause gynecologic, obstetric and fertility problems. Obstetrical complications are reported to occur more commonly with mullerian duct anomalies, such as postpartum hemorrhage (PPH). Uterine compression sutures may be effective in controlling PPH in these conditions as an alternative to hysterectomy, especially if the patient has a desire to conceive. As the shape of the uterus is changed in congenital malformation, the usage of compression sutures such...

Mehmet Vural; Nuray Boyar; Fazilet Kübra Boynukal?n; ?brahim Hakan Boyar

2011-01-01

364

The Kolar Schist Belt: A possible Archaean suture zone  

Science.gov (United States)

The Kolar Schist Belt represents a N-S trending discontinuity in the structures, lithologies, and emplacement and metamorphic ages of late Archean gneisses. The suggestion of a much older basement on the west side of the belt is not seen on the east. Within the schist belt amphibolites from each side have distinctly different chemical characteristics, suggesting different sources at similar mantle depths. These amphibolites were probably not part of a single volcanic sequence, but may have formed about the same time in two completely different settings. Could the amphibolites with depleted light REE patterns represent Archean ocean floor volcanics which are derived from a mantle source with a long term depletion of the light REE? Why are the amphibolites giving an age which may be older than the exposed gneisses immediately on either side of the belt? These results suggest that it is necessary to seriously consider whether the Kolar Schist Belt may be a suture between two late Archean continental terranes.

Hanson, G. N.; Krogstad, E. J.; Ragamani, V.; Balakrishnan, S.

365

Deep electromagnetic soundings conducted in Trans-European Suture Zone  

Science.gov (United States)

A consortium of nine geophysical institutions recently carried out a large-scale geomagnetic experiment focused on revealing the deep electrical structure beneath central and eastern Europe around the Trans-European Suture Zone (TESZ), the region's first-order geological lineament. The TESZ is considered a broad zone of deformation that crosses all of Europe, from the British Isles in the northwest to the Black Sea area in the southeast, and it most likely continues in North America [Keller and Hatcher, 1999].The geomagnetic experiment was called Central Europe Mantle Geoelectrical Structure (CEMES). Initiated by Polish scientists, geophysicists from eight other countries joined the project during a NATO Advanced Research Workshop held in the spring of 2001 in Belsk, Poland. The experimental phase of the project was held from 2001 through 2002; and altogether, 12 geomagnetic observatories, the international codes of which are shown among others in Figure 1, took part in acquiring the data. They will serve the objective of inferring information on the mantle conductivity structures beneath the region of TESZ, as well as beneath surrounding units, specifically the western part of the East European Craton (EEC), Variscides, including the Bohemian Massif, the Carpathians, and the Pannonian Basin.

Semenov, Vladimir Yu.; Jozwiak, Waldemar; Pek, Josef

366

Silicon Mach-Zehnder modulator of extinction ratio beyond 10 dB at 10.0-12.5 Gbps.  

Science.gov (United States)

Silicon Mach-Zehnder modulators with reduced series resistance in lateral PN junction rib-waveguide phase shifters for enhanced high-speed response are fabricated and characterized. Extinction ratio higher than 10 dB is obtained at 10.3-11.7 Gbps with mask margins of 27% (10.3-Gbps 10GBE), 16% (10.7-Gbps STM-64/OC-192) and 10% (11.3-Gbps STM-64/OC-192) in eye-diagram measurements incorporating mask tests using a RF cut-off filter. In unfiltered eye-diagram measurements without mask tests, extinction ratio higher than 13 dB is obtained at 10.0-12.5 Gbps. The silicon modulators reveal high-speed performance comparable with that of lithium-niobate modulators in high-speed optical fiber telecommunications. PMID:22274027

Ogawa, Kensuke; Goi, Kazuhiro; Tan, Yong Tsong; Liow, Tsung-Yang; Tu, Xiaoguang; Fang, Qing; Lo, Guo-Qiang; Kwong, Dim-Lee

2011-12-12

367

CFD Analysis of Coolant Flow in VVER-440 Fuel Assemblies with the Code ANSYS CFX 10.0  

International Nuclear Information System (INIS)

From the aspect of planning the power upgrading of nuclear reactors - including the VVER-440 type reactor - it is essential to get to know the flow field in the fuel assembly. For this purpose we have developed models of the fuel assembly of the VVER-440 reactor using the ANSYS CFX 10.0 CFD code. At first a 240 mm long part of a 60 degrees segment of the fuel pin bundle was modelled. Implementing this model a sensitivity study on the appropriate meshing was performed. Based on the development of the above described model, further models were developed: a 960 mm long part of a 60-degree-segment and a full length part (2420 mm) of the fuel pin bundle segment. The calculations were run using constant coolant properties and several turbulence models. The impacts of choosing different turbulence models were investigated. The results of the above-mentioned investigations are presented in this paper. (authors)

368

Nasal tip narrowing: Minimally invasive suture technique for thick nose tip  

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Full Text Available Introduction: Suture techniques are mandatory methods to shape the nasal cartilages. For purposes of achieving a better contour on thick or globose nasal tips, the authors have approached a controlled intercrural and minimally invasive suture technique and the results obtained by submitting 34 patients to rhinoplasty. Objective: Illustrate the intercrural suture technique as a treatment for a thick or globose nasal tip under closed rhinoplasty and explain the esthetical results. Method: Retrospective study with 34 patients' clinical documents and photographs (5 male and 20 female aged between 16 and 52, who were submitted to the thick or globose nasal tip rhinoplasty as an anatomic element found in the physical examination. In all the cases, closed rhinoplasty technique was used. A suture that cannot be absorbed is performed throughout the intermediate process. The study was performed at the Brazilian Red Cross Hospital in the State of Paraná and Sugisawa Hospital in 2009 and 2010. Patients were operated on by the main author and the junior doctors under training. Results: The controlled intercrural suture enabled the nasal tip to be narrowed and improved the shape in the frontal and lateral angles of the nasal tip. Conclusion: Controlled intercrural suture is a minimally invasive method providing the thick nasal tip narrowing with satisfactory results.

Nassif Filho, Antonio Celso Nunes

2011-07-01

369

Postauricular fascial flap and suture otoplasty: a prospective outcome study of 227 patients.  

Science.gov (United States)

The anterior scoring technique is criticised for a higher risk of haematoma related complications while the suture techniques for suture-extrusion and recurrence. Horlock et. al. described a suture otoplasty with addition of a postauricular fascial flap to reduce suture extrusion and noted recurrence rates of 8%. We report the senior author's experience with this technique in 227 consecutive cases. All cases were done by or under supervision of the senior author and the data collected prospectively. Complications, recurrence, revision rate and results as recorded were analysed. A total of 10 (7 early 3 late) complications were recorded (4.4%). Suture extrusion (n = 6, 2.64%), Keloids (n = 3, 1.32%), Infection, anterior skin necrosis (n = 1 each, 0.44%). A total of 6 unilateral and 5 bilateral cases had a recurrence (3.67% total ears) and 97% of recorded outcomes were reported as good or excellent results. The low complication rate seems to support the hypothesis that the fascial flap prevents suture extrusion and reduces risk of recurrence. Lack of Anterior dissection avoids risks of bleeding and haematoma. PMID:22071456

Sinha, Manish; Richard, Bruce

2012-03-01

370

Influence of different types of surgical suture material on the intensity of tissue reaction in oral cavity  

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Full Text Available Throughout the history the most diverse suture material have been used for closing and suturing surgical wounds. The four basic features of suture material are described: knot safety, stretch capacity, tissue reactivity and wound safety. Tissue reaction, even the minimum one, which develops during the first to seven days after applying the suture in the tissue. The aim of this study was to investigate influence of a monofilament suture material (nylon on the intensity of local tissue reaction in experimental conditions, and to compare it with the multifilament suture used in the routine practice of oral surgery (silk. This investigation is a prospective experimental study carried out on Wistar rats. The experiment included 30 animals, in which Black Silk (thickness 4-1 and Nylon (thickness 4-0 were applied in the upper and lower jaw, respectively. To monitor tissue reaction on different suture materials the following parameters were used: coagulum formation, presence of polymorphonuclear leukocytes, presence of macrophages and granuloma, formation of epithelial bridge and connective tissue, collagen synthesis, granulomatous tissue formation and presence of fibrous tissue. After comparing parameters for the intensity of tissue reaction to the investigate suture materials by suturing the oral mucosa, certain advantage could be given to the monofilament suture materials.

Mirkovi? Siniša M.

2008-01-01

371

Characterization of carbon nanofibre-reinforced polypropylene foams.  

Science.gov (United States)

In this paper, carbon-nanofibre-reinforced polypropylene foams were prepared and characterized regarding their foaming behaviour, cellular structure and both thermo-mechanical as well as electrical properties. Polypropylene (PP) nanocomposites containing 5, 10 and 20 wt% of carbon nanofibres (CNF) and a chemical blowing agent were prepared by melt-mixing inside a twin-screw extruder and subsequently water-cooled and pelletized. The extruded nanocomposites were later foamed using a one-step compression-moulding process. The thermo-mechanical properties of the CNF-reinforced PP foams were studied, analyzing the influence of the carbon nanofibres on the cellular structure and subsequent thermo-mechanical behaviour of the foams. Carbon nanofibres not only seemed to act as nucleating agents, reducing the average cell size of the foams and increasing their cell density for similar expansion ratios, but also helped produce mechanically-improved foams, even reaching for the 20 wt% CNF-reinforced ones a specific modulus around 1.2 GPa x cm3/g for densities as low as 300 kg/m3. An increasingly higher electrical conductivity was assessed for both the solids as well as the foams with increasing the amount of carbon nanofibres. PMID:20352783

Antunes, M; Velasco, J I; Realinho, V; Arencón, D

2010-02-01

372

Morphology and properties of recycled polypropylene/bamboo fibers composites  

International Nuclear Information System (INIS)

Polypropylene (PP) is among the most widely used thermoplastics in many industrial fields. However, like other recycled polymers, its properties usually decrease after recycling process and sometimes are degraded to poor properties level for direct re-employment. The recycled products, in general, need to be reinforced to have competitive properties. Short bamboo fibers (BF) have been added in a recycled PP (RPP) with and without compatibilizer type maleic anhydride polypropylene (MAPP). Several properties of composite materials, such as helium gas permeability and mechanical properties before and after ageing in water, were examined. The effects of bamboo fiber content and fiber chemical treatment have been also investigated. We showed that the helium permeability increases if fiber content is higher than 30% because of a poor adhesion between untreated bamboo fiber and polymer matrix. The composites reinforced by acetylated bamboo fibers show better helium permeability due to grafting of acetyl groups onto cellulose fibers surface and thus improves compatibility between bamboo fibers and matrix, which has been shown by microscopic observations. Besides, mechanical properties of composite decrease with ageing in water but the effect is less pronounced with low bamboo fiber content.

373

Aging effects of polypropylene used in heating systems  

Science.gov (United States)

The aging effects of polypropylene targets used in heating systems were investigated using the nuclear reaction analysis (NRA) technique. Deuterium beams of energies 900, 1200 and 1500 keV, supplied from the University of Jordan Van de Graaff accelerator, were employed. Different working times between 1 and 6 years were investigated in addition to a new fresh sample which was considered as standard. The reactions resulting from 12C(d,p) 13C, 16O(d,p 1) 17O and 14N(d,? 1) 12C were monitored. The oxygen and nitrogen concentrations data reveal similar behavior for both elements. The initial concentration of both quantities resulting from fusion, processing and storage times decreases and then gradually increases to reach higher levels than those initially, as the working time is increased. A model, based on mass transfer of air-oxygen and nitrogen and solubility of polypropylene to both elements, was proposed to explain our observation. The uptake of these light impurities and their presence at high concentration levels in the thermopipes material, in addition to microstructural effects, are responsible for the degradation of many of its observed properties. The main effect was demonstrated by the influence of several parameters on strength and embrittlement.

Arafah, D.-E.; Ramadin, Y.; Hammad, M.; Zihlif, A.

1993-03-01

374

Aging effects of polypropylene used in heating systems  

International Nuclear Information System (INIS)

The ageing effects of polypropylene targets used in heating systems were investigated using the nuclear reaction analysis (NRA) technique. Deuterium beams of energies 900, 1200 and 1500 keV, supplied from the University of Jordan Van de Graaff accelerator, were employed. Different working times between 1 and 6 years were investigated in addition to a new fresh sample which was considered as standard. The reactions resulting from 12C(d,p)13C, 16O(d,p1)17O and 14N(d,?1)12C were monitored. The oxygen and nitrogen concentrations data reveal similar behaviour for both elements. The initial concentration of both quantities resulting from fusion, processing and storage times decreases and then gradually increases to reach higher levels than those initially, as the working time is increased. A model, based on mass transfer of air-oxygen and nitrogen and solubility of polypropylene to both elements, was proposed to explain our observation. The uptake of these light impurities and their presence at high concentration levels in the thermopipes material, in addition to microstructural effects, are responsible for the degradation of many of its observed properties. The main effect was demonstrated by the influence of several parameters on strength and embrittlement. (Author)

375

Does the type of suturing technique used affect astigmatism after deep anterior lamellar keratoplasty in keratoconus patients?  

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Full Text Available Banu Torun Acar, Ece Turan Vural, Suphi AcarHaydarpasa Numune Education and Research Hospital, Ophthalmology Clinic, Istanbul, TurkeyPurpose: To compare the effect of three different suturing techniques on astigmatism after deep anterior lamellar keratoplasty (DALK in patients with keratoconus.Methods: In this retrospective study, 54 eyes of 54 patients with advanced keratoconus underwent DALK with three suturing techniques: single running, interrupted running, and combined interrupted and running. Postkeratoplasty astigmatism was evaluated during examinations 1, 3, and 6 months postoperatively and 2 months after completing suture removal.Results: Twenty-four eyes had single running sutures, 16 eyes had interrupted sutures, and in 14 eyes the suturing technique used was combined interrupted and running sutures. Mean age was 25.6 ± 5.9 years, 27.3 ± 6.8 years, and 26.5 ± 5.7 years (P = 0.422, and postoperative astigmatism 1 month after surgery was 3.79 ± 1.19 D, 5.56 ± 1.78 D, and 4.21 ± 1.55 D in the three groups, respectively (P = 0.012. However, 2 months after completing the suture removal, final postoperative astigmatism was 3.43 ± 1.44 D, 3.87 ± 1.38 D, and 3.71 ± 1.46 D (P = 0.846. Final astigmatism less than 4 D was seen in 18 cases (75% in the single running group, nine cases (56.2% in the interrupted running group, and nine cases (64.2% in the combined interrupted and running group (P = 0.08.Conclusion: Postkeratoplasty astigmatism is comparable with three different suturing techniques used in patients with keratoconus after completing suture removal in DALK. Due to earlier suture removal in DALK, the type of suturing technique used is not considerably important.Keywords: astigmatism, deep anterior lamellar keratoplasty, suturing technique

Acar BT

2011-04-01

376

TENSILE STRENGTH CHARACTERISTICS OF POLYPROPYLENE COMPOSITES REINFORCED WITH STONE GROUNDWOOD FIBERS FROM SOFTWOOD  

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Full Text Available The behavior of stone groundwood / polypropylene injection-molded composites was evaluated with and without coupling agent. Stone groundwood (SGW is a fibrous material commonly prepared in a high yield process and mainly used for papermaking applications. In this work, the use of SGW fibers was explored as a reinforcing element of polypropylene (PP composites. The surface charge density of the composite components was evaluated, as well as the fiber’s length and diameter inside the composite material. Two mixing extrusion processes were evaluated, and the use of a kinetic mixer, instead of an internal mixer, resulted in longer mean fiber lengths of the reinforcing fibers. On the other hand, the accessibility of surface hydroxyl groups of stone groundwood fibers was improved by treating the fibers with 5% of sodium hydroxide, resulting in a noticeable increase of the tensile strength of the composites, for a similar percentage of coupling agent. A new parameter called Fiber Tensile Strength Factor is defined and used as a baseline for the comparison of the properties of the different composite materials. Finally the competitiveness of stone groundwood / polypropylene / polypropylene-co-maleic anhydride system, which compared favorably to sized glass-fiber / polypropylene GF/PP and glass-fiber / polypropylene / polypropylene-co-maleic anhydride composite formulations, was quantified by means of the fiber tensile strength factor.

Joan P. López,

2012-06-01

377

Susceptibility to scratch surface damage of wollastonite- and talc-containing polypropylene micrometric composites  

International Nuclear Information System (INIS)

The paper describes the effect of wollastonite and talc on the scratch deformation behavior of low and high crystallinity polypropylenes under identical test conditions. The vertical resolution of atomic force microscopy and lateral resolution of scanning electron microscopy is utilized to examine the characteristics of scratch damage. Contrary to the expectations that high crystallinity and stiffness of polypropylene composites should increase resistance to scratch deformation, the susceptibility to mechanical deformation depends on bonding of mineral particles to the polymer matrix. Scratch deformed regions in neat polypropylenes were free of voids and grooves, while reinforced-polypropylenes exhibited voids and debonding/detachment of filler particles. The severity of plastic deformation in reinforced polypropylenes is a function of debonding/detachment of mineral particles, which is comparatively more for talc-reinforced polypropylenes than wollastonite-reinforced polypropylenes because of the layered structure of talc that encourages delamination. Usage of coating and coupling agents improved the resistance to scratch deformation by promoting adhesion and bonding between the reinforcement and matrix

378

Study of polypropylene/polybutene blends modified by gamma irradiation and (high melt strength polypropylene)/polybutene blends  

Energy Technology Data Exchange (ETDEWEB)

It is well-known that polypropylene (PP) is difficult to process as a consequence of its linear structure. It is also known that grafting of long-chain branches on PP backbone using ionizing radiation is an effective approach to achieve high melt strength polypropylene (HMS PP). Chain-scission and, in minor extend, crosslinking and grafting are the predominant reaction in order to branch PP backbone. However, if multifunctional monomers are used to promote the grafting reaction, crosslinking can surpass chain scission and grafting, reducing drawability. Therefore, in an effort to enhance the processability and so the drawability, it has been found helpful to add a small amount of polybutene-1. Gamma irradiation technique was used to induce chemical changes in blends of PP and polybutene in acetylene atmosphere (crosslinker promoter) and in HMSPP/polybutene blends. The samples were irradiated with a {sup 60}Co source with doses of 12.5 and 20 kGy in the presence of acetylene. In this work, two different methods of blends processing were compared regarding rheological and mechanical properties. Effects on the strength and elongation at the yield point and at rupture were observed by mechanical tests and showed decrease of tensile strength and increase of elongation at rupture for samples obtained by irradiation of blends. The results from rheology demonstrated an increase in melt strength and drawability of blends.

Yoshiga, Adriana; Otaguro, Harumi; Lima, Luis Filipe C.P. [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, CEP 05508-900, Sao Paulo-SP (Brazil); Artel, Beatriz W.H. [Empresa Brasileira de Radiacao, Av. Cruzada Bandeirante, 269, CEP 06700-000, Cotia-SP (Brazil); Parra, Duclerc F.; Rodrigues Bueno, Jeferson; Shinzato, Rodrigo [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, CEP 05508-900, Sao Paulo-SP (Brazil); Farrah, Marcelo [BRASKEM, III Polo Petroquimico, Via Oeste, Lote 5, CEP 95853-000, Triunfo-RS (Brazil); Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, CEP 05508-900, Sao Paulo-SP (Brazil)], E-mail: ablugao@ipen.br

2007-12-15

379

Molecular origin of demixing, prior to crystallization, of atactic polypropylene/isotactic polypropylene blends upon cooling from the melt  

Science.gov (United States)

An amorphous 50/50 atactic polypropylene (aPP)/isotactic polypropylene (iPP) mixture at 125 °C was simulated using a second nearest neighbor diamond lattice and a three states rotational isometric state model. The result suggests that at the liquidlike density that corresponds to the atmospheric pressure, aPP prefers to interact with other aPP chains rather than with iPP chains. The result is consistent with the inference of Keith and Padden [J. Appl. Phys. 35, 1286 (1964)] that aPP and iPP will tend to separate from one another in their melt at 125 °C, before the onset of crystallization of iPP. The tendency for immiscibility of the amorphous aPP/iPP blend is likely attributed to the presence of short syndiotactic sequences in the aPP chains adopting all-trans conformations. The attractive intermolecular interaction of pairs of such subchains at 125 °C promotes the separation of aPP from iPP. This interaction is weakened at higher temperature, where aPP and iPP become miscible. The result also shows that miscibility of the blend increases with increasing pressure. However, the origin of the pressure effect is not clear.

Choi, Phillip; Mattice, Wayne L.

2004-11-01

380

Study of polypropylene/polybutene blends modified by gamma irradiation and (high melt strength polypropylene)/polybutene blends  

International Nuclear Information System (INIS)

It is well-known that polypropylene (PP) is difficult to process as a consequence of its linear structure. It is also known that grafting of long-chain branches on PP backbone using ionizing radiation is an effective approach to achieve high melt strength polypropylene (HMS PP). Chain-scission and, in minor extend, crosslinking and grafting are the predominant reaction in order to branch PP backbone. However, if multifunctional monomers are used to promote the grafting reaction, crosslinking can surpass chain scission and grafting, reducing drawability. Therefore, in an effort to enhance the processability and so the drawability, it has been found helpful to add a small amount of polybutene-1. Gamma irradiation technique was used to induce chemical changes in blends of PP and polybutene in acetylene atmosphere (crosslinker promoter) and in HMSPP/polybutene blends. The samples were irradiated with a 60Co source with doses of 12.5 and 20 kGy in the presence of acetylene. In this work, two different methods of blends processing were compared regarding rheological and mechanical properties. Effects on the strength and elongation at the yield point and at rupture were observed by mechanical tests and showed decrease of tensile strength and increase of elongation at rupture for samples obtained by irradiation of blends. The results from rheology demonstrated an increase in melt strength and drawability of blends

 
 
 
 
381

Comparison of a polyglycolic-polylactic acid suture to black silk and plain catgut in human oral tissues.  

Science.gov (United States)

A polylactic-polyglycolic acid synthetic absorbable suture material (Vicryl, Polyglactin 910) was compared with black silk and plain catgut in human oral tissues. Inflammation was graded clinically and histologically after seven days. Handling characteristics, including suture retention, were evaluated. Vicryl and black silk sutures produced comparable inflammation after seven days. Plain catgut sutures were usually absorbed before seven days, but when retained generally produced a more severe reaction. The polylactic-polyglycolic acid suture is braided and dyed, and has handling characteristics similar to those of black silk. Although they are absorbable, Vicryl sutures may be retained longer than desired and probably should be used like silk when exposed to the oral cavity. PMID:280644

Racey, G L; Wallace, W R; Cavalaris, C J; Marguard, J V

1978-10-01

382

Development of polypropylene/wood flour ecocomposites. Evaluation of silane as coupling agent  

International Nuclear Information System (INIS)

The effects of Pinus Sylvestris wood flour as filler in polypropylene matrix was evaluated. The mechanical properties and the morphology of different wood flour/polypropylene composites (WPC) were studied. The composites materials were prepared with several amounts of wood flour from 10 to 30% wt. Mechanical properties show that the wood flour incorporation increases the rigidity of the composites. Morphological analysis indicates that agglomerates are formed, with amounts exceeding 30% of wood flour. For the silane--treated composites, the dispersion of the filler into the polypropylene (PP) matrix improved. Shore D hardness of the composites is decreased with the addition of the coupling agent.

383

Mechanical Properties and Energy-saving Effect of Polypropylene Fiber Foam Concrete  

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Full Text Available Compared with ordinary concrete, foam concrete possesses advantages such as lightweight, heat insulation, etc., but the internal bubbles have of great influence on its strength. This study examined the impa