101
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Braga M, Rink M, Pavan A. Variations in the fracture behaviour of polyethylene pipe materials induced by thermal treatments. POLYMER 1991. [DOI: 10.1016/0032-3861(91)90136-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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102
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Torrisi MR, Pavan A, Lotti LV, Migliaccio G, Pascale MC, Covelli E, Leone A, Bonatti S. Anchorage-dependent surface distribution and partition during freeze-fracture of viral transmembrane glycoproteins. J Histochem Cytochem 1990; 38:1421-6. [PMID: 2401782 DOI: 10.1177/38.10.2401782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have compared in the same cell type the surface distribution and partition in freeze-fractured plasma membranes of Sindbis virus glycoproteins in three different situations: (i) in permanently transformed cells that express the glycoproteins as the only viral product; (ii) in cells in which prebound viruses were forced to fuse with the plasma membrane by low pH treatment; (iii) in virus-infected cells. We report here that the viral proteins expressed on the surface of transfected cells show a uniform and unclustered distribution; conversely, in Sindbis virus-infected cells they appear clustered, regionally distributed, and always associated with budding viruses (i.e., interacting with the nucleocapsid on the cytosolic side of the membrane). Furthermore, the viral proteins expressed on transfected cells or implanted by low pH-mediated fusion partition during freeze-fracture with the exoplasmic faces of the cell plasma membranes, whereas an opposite partition is observed in infected cells. These results strongly suggest that in infected cells the clustering and the partition with the protoplasmic faces of the plasma membrane depend only on the strong "anchorage" of the glycoproteins to the nucleocapsid.
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103
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Zanichelli C, Rink M, Pavan A, Ricco T. Experimental analysis of inertial effects in the impact testing of polymers. POLYM ENG SCI 1990. [DOI: 10.1002/pen.760301802] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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104
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Pavan A, Mancini P, Lucania G, Frati L, Torrisi MR, Pinto da Silva P. High-resolution surface views of human lymphocytes during capping of CD4 and HLA antigens as revealed by immunogold fracture-flip. J Cell Sci 1990; 96 ( Pt 1):151-7. [PMID: 2373738 DOI: 10.1242/jcs.96.1.151] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The surface ultrastructure of lymphocytes during capping of two transmembrane proteins is shown. As seen by fracture-flip the plasma membranes of human lymphocytes are covered by a high density of surface particles. Incubation in 30% glycerol leads to aggregation of these surface particles. Immunogold labelling shows that the transmembrane proteins bearing HLA class I and CD4 antigens are confined to the particle aggregates. These results indicate that surface particles revealed by fracture-flip represent surface protrusions of integral membrane proteins seen as intramembrane particles in freeze-fractured lymphocytes. During capping HLA or CD4 antigens aggregate into progressively larger patches and, finally, into single caps. As revealed by fracture-flip the patches/caps are seen as clearly differentiated raised platforms that are clearly and sharply demarcated relative to contiguous areas of the surface. In non-patched (non-capped) regions, the pattern of distribution and apparent density of surface particles remain unaltered. Immunogold labelling clearly demarcates patches and caps, and shows that virtually no antigen molecules remain dispersed over the non-patched (non-capped) regions. Estimates of the surface density of either HLA or CD4 antigens over the capped areas point to high planar concentrations of the transmembrane proteins that bear these antigens.
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105
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Pavan A, Mancini P, Cirone M, Frati L, Torrisi MR, Pinto da Silva P. Capping of HLA antigens in human lymphocytes as followed by immunogold label-fracture. J Histochem Cytochem 1989; 37:1489-96. [PMID: 2778307 DOI: 10.1177/37.10.2778307] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We used immunogold label-fracture to follow the migration of HLA I class and HLA II class antigens during capping as induced by specific monoclonal antibodies. Capping is achieved through a process of clustering and "consolidation" of clusters into larger patches and, finally, a single cap. All receptors appear to cluster from the very start, with no "stray" molecules joining already formed patches. Characterization of exoplasmic and protoplasmic fracture-faces of capping cells fails to reveal any corresponding accumulation of intramembrane particles and/or subtler rugosities. Our results are consistent with the concepts that view the migration of capping molecules as contemporaneous with the efflux of noncapping integral membrane proteins.
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106
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Torrisi MR, Cirone M, Pavan A, Zompetta C, Barile G, Frati L, Faggioni A. Localization of Epstein-Barr virus envelope glycoproteins on the inner nuclear membrane of virus-producing cells. J Virol 1989; 63:828-32. [PMID: 2536106 PMCID: PMC247756 DOI: 10.1128/jvi.63.2.828-832.1989] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epstein-Barr virus-producing cells were used as a model to analyze, with a fracture-immunolabel technique, the distribution, behavior on fracture, and extent of glycosylation of viral transmembrane glycoproteins at the inner nuclear membrane. Surface and fracture immunolabeling with two monoclonal antibodies directed against the carbohydrate or polypeptide portions of the major viral envelope glycoproteins gp350/220 showed the following. (i) The glycoproteins present on the inner and outer nuclear membranes were labeled only with the monoclonal antibody directed against the polypeptide chain, whereas over the surface of virus-producing cells and on mature virions the labeling was dense and uniformly distributed with both monoclonal antibodies. (ii) The glycoproteins were nonuniformly distributed only over the inner nuclear membranes; at the sites of viral budding, the glycoproteins showed a preferential partition with the protoplasmic face. Since fully glycosylated glycoproteins were not present on the nuclear membranes, our observations support the proposed model of herpesvirus maturation. The peculiar distribution and partition on fracture of the envelope glycoproteins on the inner nuclear membrane are similar to those of Sindbis virus envelope glycoproteins on the plasma membrane of infected cells. Therefore, our results suggest that inner nuclear membranes may behave like plasma membranes during viral assembly.
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107
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Pavan A, Mancini P, Frati L, Torrisi MR, da Silva PP. Molecular cytochemistry of CD3 and CD4 antigens in human lymphocytes as studied by label-fracture and by fracture-label. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 978:158-68. [PMID: 2783650 DOI: 10.1016/0005-2736(89)90511-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Label-fracture and fracture-label membrane immunocytochemistry are used to analyze the surface distribution, dynamics and partition on fracture of CD3 and CD4 antigens of human T lymphocytes. Redistribution of the antigens, induced by treatment at 37 degrees C with specific monoclonal antibodies, results in patching and capping of the labeling as observed in label-fractured specimens. Examination of platinum/carbon replicas of freeze-fractured plasma membranes of antibody-treated cells does not reveal recognizable domains of intramembrane particles. However, in cells where the aggregation of intramembrane particles is induced by incubation with glycerol, colloidal gold-labeled CD3 and CD4 molecules are seen confined to particulate domains of the membrane. Therefore, the lack of visible aggregation of intramembrane particles in patched or capped regions of the membrane implies that migration of CD3 and CD4 antigens with concentration in domains of the membrane is achieved contemporaneously with export of other non-capped integral membrane proteins from the same regions, in a process of diffusional equilibrium. Examination of fracture-labeled specimens shows that CD4 molecules partition on fracture with the inner protoplasmic face of the plasma membrane. This partition illustrates the transmembrane attitude of the antigen molecule and is a probable consequence of interaction of the protein with other components of the membrane or with the cytoskeleton.
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108
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Lotti LV, Pavan A, Mancini P, Frati L, Torrisi MR. Wheat germ agglutinin fracture-label of Golgi apparatus membranes in proliferating cells. CELL BIOLOGY INTERNATIONAL REPORTS 1988; 12:597-605. [PMID: 3197118 DOI: 10.1016/0309-1651(88)90152-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The thin section fracture-label technique has been recently used to analyze the distribution and compartmentalization of fully glycosylated components on intracellular membranes. Labelling with the lectin wheat germ agglutinin over the freeze-fractured membranes of Golgi apparatus in various secretory and non-secretory cells as well as in human peripheral lymphocytes was always very weak or absent even over the trans-most cisternae. In order to investigate if the labelling density may reflect the cellular activity in membrane biogenesis, we used in this study wheat germ agglutinin fracture-label of rapidly proliferating cells and mitogen-activated lymphocytes. Labelling over the fractured cisternae of the medial and trans portions of the Golgi apparatus was intense. Treatment with cycloheximide of proliferating cells induced a drastic reduction of the labelling over the Golgi cisternae.
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109
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Torrisi MR, Pavan A, Lotti LV, Zompetta C, Faggioni A, Frati L. Nonrandom distribution of epidermal growth factor receptors on the plasma membrane of human A431 cells. Exp Cell Res 1988; 175:326-33. [PMID: 3360057 DOI: 10.1016/0014-4827(88)90196-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The localization of epidermal growth factor (EGF) receptors over the plasma membranes of human epidermoid carcinoma A431 cells was analyzed at the electron microscopic level using surface replica techniques and conventional thin sections, in combination with immunocytochemistry. Immunolabeling was performed using two distinct monoclonal antibodies directed against the extracellular portion of the receptor, followed by protein A-colloidal gold conjugates. Unexpectedly, with the first monoclonal antibody used, the distribution of the receptors in both unfixed and glutaraldehyde-fixed cells was clearly regionalized, showing a preferential localization of the immunolabeling at the cell periphery as well as over the areas rich in microvilli and in coated and uncoated pits. A similar pattern of distribution was observed also with the other monoclonal antibody, but only when the cells were fixed with glutaraldehyde before immunolabeling. Treatment with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate modifies this distribution, inducing a more disperse pattern. Our observations suggest that a minor group of EGF receptors, which may represent the high-affinity receptors, presents a regional distribution, similar to that described for typical recycling receptors.
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110
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Torrisi MR, Lotti LV, Pavan A, Migliaccio G, Bonatti S. Free diffusion to and from the inner nuclear membrane of newly synthesized plasma membrane glycoproteins. J Cell Biol 1987; 104:733-7. [PMID: 3818797 PMCID: PMC2114548 DOI: 10.1083/jcb.104.3.733] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Sindbis virus-infected baby hamster kidney (BHK) cells were analyzed by thin section fracture-label. Specific immunolabel with antiviral glycoprotein antibodies was used in conjunction with colloidal gold-conjugated protein A. As we previously reported (Torrisi, M. R., and S. Bonatti, 1985, J. Cell Biol., 101:1300-1306), Sindbis transmembrane glycoproteins are present in the inner nuclear membrane as well as in the outer nuclear membrane, endoplasmic reticulum, Golgi stacks and vesicles, and plasma membranes. Viral glycoproteins located on the inner nuclear membrane resemble those present on the outer membrane in terms of amount, distribution, and preferential partition after fracture. We show in this paper that Sindbis glycoproteins after treatment with cycloheximide are removed from the inner nuclear membrane with the same kinetics as their counterparts present on the outer membrane. This finding strongly suggests that newly synthesized transmembrane glycoproteins may freely diffuse to and from the inner nuclear membrane before entering into the intracellular transport pathway to the plasma membrane.
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111
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Pavan A, Lotti LV, Torrisi MR, Migliaccio G, Bonatti S. Regional distribution of Sindbis virus glycoproteins on the plasma membrane of infected baby hamster kidney cells. Exp Cell Res 1987; 168:53-62. [PMID: 3780874 DOI: 10.1016/0014-4827(87)90415-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sindbis virus-infected baby hamster kidney (BHK) cells were analysed in surface replicas or conventional thin sections after specific immunolabelling with antiviral glycoprotein antibodies in conjunction with colloidal gold-conjugated protein A. Newly synthesized viral glycoproteins were detected, beginning 1 1/2 h after infection, while the virus maturation started 3 h after infection. The glycoproteins appeared to be inserted on the plasma membrane in large spots located mainly in the central area of the cells: no clustering of the labelling was detected. Later, the glycoproteins appeared to arrange linearly in regions in the medial portion of the cells. No labelling was found in the peripheral area or on the cell edges. A drastic change in the surface labelling was detected following the commencement of virus maturation: gold particles were organized mostly in small clusters, each labelling a budding virus. Very few glycoproteins appeared not to be involved in budding figures. The maturation of the virus was clearly regionalized, but during this time it also involved the peripheral area and the cell edges; preferential budding in narrow cellular processes was often observed. It appeared thus that either isolated glycoproteins soon after infection, or clustered glycoproteins at later times, are strictly regionalized on the plasma membrane: however, the early post-infection distribution is clearly different from that seen later during virus maturation. Our experiments support the concept of discrete plasma membrane domains even in cells that do not display distinct specialization of their surface.
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112
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Pacilli L, Cochi S, Ferraro P, Fioravanti D, Ingletto D, Pavan A, Zoli V, Angeloni P, De Laurenzi A, Mannella E. B-chronic lymphocytic leukemia with cells binding sheep erythrocytes during prolymphocytoid transformation. Haematologica 1985; 70:250-3. [PMID: 3932156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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113
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Pavan A. [Chronic headache and personality traits]. MINERVA PSICHIATRICA 1983; 24:37-42. [PMID: 6656548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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114
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Pavan A. [Anxiety and new technics of control]. MINERVA PSICHIATRICA 1982; 23:27-31. [PMID: 7047972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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115
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Rigon F, Pinello L, Pavan A, Monciotti C, Zancan L. [Infantile obesity: clinical and social aspects (author's transl)]. LA PEDIATRIA MEDICA E CHIRURGICA 1981; 3:541-4. [PMID: 7343952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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116
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Tonietti G, Caruso L, Ranucci A, Pavan A, Premrov MG. [Incidence, type and significance of anti-myocardial autoantibodies in patients undergoing cardiac surgery]. BOLLETTINO DELLA SOCIETA ITALIANA DI BIOLOGIA SPERIMENTALE 1981; 57:1237-41. [PMID: 7284098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The incidence of anti-myocardial autoantibodies was investigated in 62 patients suffering from congenital or acquired cardiopathy prior to and 1, 10 and 20 days after cardiac surgery. Anti-myocardial autoantibodies were present in about 23.7 per cent of patients even before surgery, practically doubled one day after intervention, reached their peak (60-70 per cent) at 10 days from surgery and began to diminish at 20 days. At all times and incidence was higher in patients with acquired cardiopathy than in those with congenital heart diseases. In the large majority of cases, the autoantibodies were of the IgG class, of the striational type and in low titers. The relevance of anti-myocardial autoantibodies in the pathogenesis of cardiac lesions and the possible causes of the reversibility of the autoimmune phenomenon are discussed.
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117
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Pavan A, Riccò T, Rink M. High performance polymer blends II: Density, elastic modulus, glass transition temperatures and heat deflection temperature of polyvinylchloride-(acrylonitrile-butadiene-styrene) blends. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/0025-5416(81)90060-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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118
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Rusconi L, Pavan A, Ferruti P. Solution characterization of starch nicotinates with different degrees of esterification. Biomaterials 1981; 2:49-52. [PMID: 7236833 DOI: 10.1016/0142-9612(81)90088-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A series of starch-nicotinic acid copolymers with a degree of esterification ranging from about 15% to about 90% was prepared, and the stability in solution of two representative samples of the series was tested. The variation of some physico-chemical characteristics in the series was examined by solubility tests, viscometry and refractometry, and found to be not simply correlatable to the nicotinylation degree.
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119
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Pavan A, Riccò T, Rink M. High performance polymer blends I: The impact behaviour of blends of polyvinylchloride and acrylonitrile-butadiene-styrene terpolymers as a function of the composition of the (Styrene-Acrylonitrile) copolymer-butadiene rubber-polyvinylchloride system. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/0025-5416(80)90147-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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120
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Pavan A, Bosio M, Longo T. A comparative study of poly(glycolic acid) and catgut as suture materials. Histomorphology and mechanical properties. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1979; 13:477-96. [PMID: 155699 DOI: 10.1002/jbm.820130312] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The "quality" of poly(glycolic acid) as an absorbable suture material was investigated in comparison with catgut. Tissue reactions to poly(glycolic acid) and plain catgut were examined histomorphologically at different time intervals after implantation in rats, and compared. Four mechanical properties were also examined as relevant quality factors: elastic stiffness, tensile strength, toughness, and percent elongation at rupture of the suture material per se (unknotted). The variation of these properties in poly(glycolic acid) implants was followed since their insertion in the tissues. Histological behavior and mechanical properties appear to be more closely correlated in the case of poly(glycolic acid) than in the case of catgut, as a consequence of a greater regularity of tissue reaction towards the synthetic material. Both tissue reaction and tensile properties variation are independent of size in the case of the braided poly(glycolic acid) sutures examined. Elastic stiffness and tensile strength decrease steadily in time; toughness and ultimate elongation display an increase up to a maximum within one day since implantation, and then decrease.
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121
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Ricco T, Pavan A, Danusso F. Crazing within glassy occlusions in rubber particles of toughened glassy polymers: a micromechanical investigation. POLYMER 1979. [DOI: 10.1016/0032-3861(79)90102-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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122
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Rink M, Pavan A, Roccasalvo S. Concentration dependence of zero-shear viscosity for polymer solutions: A test of the lyons-tobolsky equation. POLYM ENG SCI 1978. [DOI: 10.1002/pen.760181005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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123
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Pavan A, Provasoli A, Moraglio G, Zambelli A. Mikrostruktur und Schmelzpunkt von stereoregulären Polymeren. Eine vorläufige experimentelle Beziehung für isotaktisches Polypropylen. Colloid Polym Sci 1978. [DOI: 10.1007/bf01784580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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124
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Rink M, Riccò T, Lubert W, Pavan A. Force–displacement evaluation of macromolecular materials in flexural impact tests. II. Influence of rubber content, degree of grafting, and temperature on the impact behavior of ABS resins. J Appl Polym Sci 1978. [DOI: 10.1002/app.1978.070220212] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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125
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Lubert W, Rink M, Pavan A. Force-displacement evaluation of macromolecular materials in flexural impact tests. I. Apparatus and data handling. J Appl Polym Sci 1976. [DOI: 10.1002/app.1976.070200421] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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