Porous copolymers of methacrylic acid with N-(2-hydroxypropyl) methacrylamide and (2-hydroxyethyl) methacrylate. Preparation, swelling and morphology

1979 ◽  
Vol 44 (6) ◽  
pp. 1925-1930 ◽  
Author(s):  
Jiří Vacík ◽  
Zdeněk Pelzbauer ◽  
Nadezhda N. Kuznetsova ◽  
Klavdia P. Papukova ◽  
Larisa K. Shataeva ◽  
...  
Keyword(s):  
Methacrylic Acid ◽  
Crosslinking Agent ◽  
Scanning Electron Microscopy Data ◽  
Hydroxyethyl Methacrylate ◽  
Electron Microscopy Data ◽  
Bulk Weight ◽  
Hydroxypropyl Methacrylamide ◽  
Porous Copolymers ◽  
Microscopy Data ◽  
Porous Morphology

Porous copolymers of methacrylic acid with N-(2-hydroxypropyl) methacrylamide or (2-hydroxyethyl) methacrylate were prepared using 1,3,5-triacryloylhexahydrotriazine as the crosslinking agent. The copolymers were characterized by their swelling, bulk weight, and morphologically by scanning electron microscopy. Data thus obtained were used in the interpretation of the formation of different porous morphology, differing in the size and ordering of globules.

Porous copolymers of methacrylic acid with N-(2-hydroxypropyl) methacrylamide and (2-hydroxyethyl) methacrylate. Study of sorption properties

1979 ◽  
Vol 44 (6) ◽  
pp. 1931-1941
Author(s):  
Jiří Vacík ◽  
Larisa K. Shataeva ◽  
Georgii V. Samsonov ◽  
Jaroslav Kálal ◽  
Jindřich Kopeček
Keyword(s):  
Methacrylic Acid ◽  
Monomeric Unit ◽  
Organic Cations ◽  
Hydroxyethyl Methacrylate ◽  
Cation Exchangers ◽  
Hydroxypropyl Methacrylamide ◽  
Irreversible Denaturation ◽  
Porous Copolymers ◽  
Univalent Organic Cations ◽  
The Relationship

Porous crosslinked copolymers of methacrylic acid with N-(2-hydroxypropyl) methacrylamide (HPMA) or (2-hydroxyethyl) methacrylate were prepared, and the relationship between their structure and the sorption of papain, bovine serumalbumin, chymotrypsinogen, pepsin, ovalbumin, insulin, novocain and oleandomycin were investigated. The presence of hydrophilic components in the gel structure makes possible additional interactions between sorbent and the compound sorbed. The occurrence of additional interactions (probably hydrogen bonds) is more pronounced with cation exchangers containing the (2-hydroxyethyl) methacrylate monomeric unit, which favourably affects the sorption of univalent organic cations but at the same time contributes to the denaturation of sorbed proteins. In contrast to univalent organic cations, cation exchangers containing the N-(2-hydroxypropyl) methacrylamide monomeric unit are more advantageous in the sorption of proteins, because due to the lower extent of additional interactions no irreversible denaturation of sorbed labile proteins takes place in this case.

Fractographic Regularities in Fatigue Failure of 17Mn1Si Steel

2014 ◽  
Vol 1040 ◽  
pp. 230-235
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Ilya Vlasov ◽  
Iryna Danyliuk ◽  
Roman Bishchak
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Scanning Electron Microscopy Data ◽  
Structural Level ◽  
Deformation And Failure ◽  
Leading Role ◽  
Electron Microscopy Data ◽  
Microscopy Data ◽  
Scanning Electron

Using the scanning electron microscopy data the main regularities of the fatigue crack propagation in the 17Mn1Si steel were studied. Based on fracture surface observation and analysis one can testify that the transition of the leading role of deformation and failure from the lower structural level to the higher one has the ordered pattern.

The effect of pH and temperature on the electrical conductivity of membranes made of methacrylic acid copolymers

1983 ◽  
Vol 48 (11) ◽  
pp. 3071-3078 ◽  
Author(s):  
Jiří Vacík ◽  
Larisa K. Shataeva ◽  
Irina A. Chernova ◽  
Georgii V. Samsonov ◽  
Jan Schauer ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Ion Exchange ◽  
Charge Carrier ◽  
Methacrylic Acid ◽  
Empirical Equation ◽  
Specific Resistance ◽  
Hydroxyethyl Methacrylate ◽  
Hydroxypropyl Methacrylamide ◽  
Carboxylic Groups ◽  
Methacrylic Acid Copolymers

The specific resistance was measured of swollen homogeneous and heterogeneous ion-exchange membranes made of methacrylic acid copolymers with N-(2-hydroxypropyl)methacrylamide and of its copolymers with 2-hydroxyethyl methacrylate. In the case of copolymers of 2-hydroxyethyl methacrylate and methacrylic acid, an increase in the methacrylic acid content raises the specific resistance of the membrane if the carboxylic groups are not ionized. At the degree of neutralization 0.5 the dependence becomes a reverse one. In copolymers of N-(2-hydroxypropyl)methacrylamide with 50 and more per cent of methacrylic acid the specific resistance of the membrane increases with increasing content of methacrylic acid in the case of the nonionized form while remaining virtually unchanged in the ionized form. All the investigated copolymers of N-(2-hydroxypropyl)methacrylamide have a maximum on the curve describing the dependence of the specific resistance on pH. This pH coincides with pH at which the diffusion mobility of the charge carrier of Na+ is highest. The dependence of the specific resistance on temperature can be described in terms of an empirical equation ρT = ρ0e-bT.

scholarly journals Structural resistance of orthodontic mini-screws inserted for extra-alveolar anchorage

2021 ◽  
Vol 34 (1) ◽  
pp. 27-34
Author(s):  
Carlos Vieira ◽  
Francyelle Pires ◽  
Wallisen Hattori ◽  
Cleudmar de Araújo ◽  
Marcelo Garcia-Junior ◽  
...  
Keyword(s):  
Stainless Steel ◽  
In Vivo Studies ◽  
Scanning Electron Microscopy Data ◽  
Insertion Angle ◽  
Electron Microscopy Data ◽  
Alloy Type ◽  
Structural Resistance ◽  
Microscopy Data ◽  
Post Hoc

The risk of fracture or strain in mini-screws is higher if diameter, length, type of alloy or insertion angle is selected inappropriately. The aims of this study were to test the structural resistance of two types of orthodontic mini-screws –one made of stainless steel and another of titanium– from an international brand and to evaluate the efficacy of two other titanium miniscrews of Brazilian origin, during an extra-alveolar anchorage procedure. The mini-screws analyzed were: Bomei stainless steel and Bomei titanium / Taiwan, Morelli titanium and Neodent titanium/ Brazil. Experiments were conducted on pig mandibles to simulate the process of extra-alveolar anchorage. Two insertion processes were used: Direct at 30º, and Indirect, starting at 60º and ending at 30º with gradual continuous movement. Strain was evaluated using Optical and Scanning Electron Microscopy. Data were evaluated using Kruskal-Wallis non-parametric statistical analysis and post hoc Tamhane test. Significant statistical differences in strain were observed among the mini-screws used in the extra-alveolar insertions, both for the direct and indirect procedures. In the indirect insertion tests, both stainless steel and titanium mini-screws suffered deformation, showing that angling can be an important factor in mini-screw failure rates. The change in angle during the insertion movement increased deformation rates independently of alloy type, increasing the risk of failure. These results could help orthodontists in choosing mini-screws for extra-alveolar anchorage, which can be performed with direct or indirect insertion. In vivo studies should be conducted to confirm the findings of this study.

scholarly journals Influence of Implant Connection, Abutment Design and Screw Insertion Torque on Implant-Abutment Misfit

2020 ◽  
Vol 9 (8) ◽  
pp. 2365
Author(s):  
Jorge Vélez ◽  
Jesús Peláez ◽  
Carlos López-Suárez ◽  
Rubén Agustín-Panadero ◽  
Celia Tobar ◽  
...  
Keyword(s):  
Insertion Torque ◽  
Scanning Electron Microscopy Data ◽  
Test Results ◽  
Tightening Torque ◽  
Screw Insertion ◽  
Electron Microscopy Data ◽  
Implant Abutment ◽  
External Connection ◽  
Microscopy Data ◽  
One Way Anova

Background: An accurate fit at the implant-abutment interface is an important factor to avoid biological and mechanical complications. The aim of this study was to evaluate the marginal misfit at the implant-abutment interface on external and Morse taper connection, with straight and angulated abutments under different insertion torque loads. Materials and Methods: A total of 120 implants were used, 60 with external connection (EC) and 60 with Morse taper connection (IC). Straight (SA) (n = 60) and angulated abutments (AA) (n = 60) were randomly screwed to each connection at different torque levels (n = 10 each): 10, 20 and 30 Ncm. All specimens were subjected to thermal and cyclic loading and the misfit was measured by scanning electron microscopy. Data were analyzed with one-way ANOVA, t-test and Kruskal-Wallis test. Results: Significant differences (p < 0.001) were found between connections and abutments regardless of the torque applied. Morse taper connections with straight and angulated abutments showed the lowest misfit values (0.6 µm). Misfit values decreased as torque increased. Conclusions: The misfit was affected by the type of connection. The type of abutment did not influence the fit in the Morse taper connection. The higher the tightening torque applied the increase in the fit of the implant-abutment interface.

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