Protective Seal Research Articles

Adhesive coronal seal of Syntac and Tetric flow following different dentine pretreatment protocols

Introduction: The purpose of this study was to test different sealer removal protocols following root canal filling before adhesive seal of access cavities. Material and methods: Forty single root teeth were selected for the study, prepared to size 60 taper .02, and filled with AH plus and a single gutta-percha cone size 55 taper .02. Excess sealer was removed with: ethanol-moisturised foam pellet (group 1), pellet and additional etch-and-rinse procedure (group 2), pellet and additional preparation with a water-cooled diamond bur (group 3) or by etch-and-rinse following temporary filling for one week (group 4). Syntac and Tetric flow were used as a secondary protective seal. A dye penetration test (centrifugation 3min / 30G; 5% methylene blue) was carried out. Results were analyzed statistically using PASW 18.0 (Kolmogorov-Smirnov-test, Kruskal-Wallis-test, Mann-Whitney-test; p < 0.05). Results: Groups 2, 3 and 4 revealed less leakage than group 1 (p < 0.05; Mann-Whitney-tests) and displayed no coloration exceeding the adhesive seal. Teeth with immediate (group 2) or delayed (group 4) adhesive seal showed similar results. Conclusion: Acid etching or bur preparation may be recommended before adhesively sealing the access cavity in single-rooted teeth. There is no need to wait until the sealer has set.

THE USE OF LASER INTERFEROMETER TO STUDY THE TEXTURE AND WEAR OF A PRESERVED BLADES MATERIAL

The works carried out until now have shown how certain parameters act on the wear of turbine blades when they touch the protective seal material. This material is used to replace the airtight labyrinths installed on the rotor and on the turbine internal casing. It is obtained by the process of thermal spraying (Atmospheric Plasma Spraying) and it is projected and deposed on the internal turbine envelop. It is used to protect the blades when it tore very easily without causing intense wear of the blades tip. In this work we showed how the surface of this material become in terms of operating parameters, what is its texture, and especially what are the different values of roughness parameters by linking it to the blades wear. The results obtaining by modelling using the method of experiments design are shown in the results part with detailed interpretations of the obtained graphs and curves.http://dx.doi.org/10.5755/j01.mech.17.4.577

Cyanoacrylate for colonic anastomosis; is it safe?

This experimental study evaluated the effectiveness and safety of using cyanoacrylate adhesive for sutureless colonic anastomosis and as a protective seal to prevent leakage. Sixty male Sprague-Dawley rats (300 +/- 10 g, 9 weeks old) were divided into three groups: in group I, the anastomosis was sutured in a single layer with 5-0 polypropylene; in group II, the anastomosis was fixed using N-butyl-2-cyanoacrylate (Histoacryl(R)); and in group III, the anastomosis was sutured and then sealed with N-butyl-2-cyanoacrylate. The rats were sacrificed on postoperative day 7. The anastomoses among the three groups were compared by measuring wound infection, anastomotic leakage, anastomotic stricture, adhesion formation, anastomotic bursting pressure, and histological appearance. No anastomotic leakage was observed in any group. Anastomotic stricture was significantly more extensive in groups II and III (p < 0.001). Bursting pressure was significantly lower in groups II and III (168 +/- 58, 45 +/- 21, and 60 +/- 38 mmHg for groups I to III, respectively, p < 0.001). The severity of inflammatory reactions was significantly greater and collagen deposition was significantly lower in groups II and III (p < 0.05). N-butyl-2-cyanoacrylate could be a useful method for sutureless colonic anastomosis based on the absence of anastomotic leakage, but it may impede healing of the colonic anastomosis. In addition, when used to seal sutured colonic anastomoses, cyanoacrylate may have a negative influence on anastomotic healing. The clinical use of N-butyl-2-cyanoacrylate in colonic anastomosis does not appear to be acceptable and safer anastomotic methods or alternative forms of cyanoacrylate should be developed.

Effect of fibrin sealant on the healing colonic anastomosis in the rat

Fibrin adhesives have been advocated as a protective seal in colonic anastomosis to prevent leakage. In order to assess the effect of fibrin glue sealing we compared the healing of sutured colonic anastomosis in the rat (group 1) with the addition of human-derived fibrin sealant (group 2). As a control for a possible reaction to foreign protein, in group 3 the sutured anastomosis was sealed with specially prepared rat fibrin adhesive. On days 2, 4 and 7, ten animals in each group were killed. Adhesion formation was scored and the in situ bursting pressure was measured. The collagen concentration and degradation were estimated by measuring hydroxyproline. Adhesion formation was significantly increased in groups 2 and 3 compared with the control group. On days 2 and 7 the bursting pressure was not different between the groups. On day 4 the bursting pressure in groups 2 and 3 was significantly lower than in group 1 (P less than 0.001). These findings correspond with the results of collagen measurements. On day 4 the concentration of hydroxyproline was significantly reduced in groups 2 and 3. Histological examination showed infiltration of neutrophilic granulocytes into the sealant on days 2 and 4; on day 7 the sealant had vanished. From these results it is concluded that fibrin sealing of the colonic anastomosis in the rat does not improve healing, as demonstrated by bursting pressure and hydroxyproline concentration. On the contrary, it seems to have a negative influence.

Interdisciplinary Conflict Analysis and Conflict Mitigation in Local Resource Management

Within the Swedish research program SUCOZOMA (Sustainable Coastal Zone Management) several conflict studies have been carried out. Whereas the detailed results of these studies are published separately, this paper reviews important results from conflict research in combination with a summarizing and generalizing discussion of approaches and main results of SUCOZOMA's resource and conflicts studies. After an analysis of interdisciplinary and theoretical research about environmental and resource use conflicts, the methodology used in SUCOZOMA is presented, a combined stakeholder and conflict analysis. It can be summarized in four main points: i) to map the stakeholders and their interests; i) to analyse the conflicts; iii) to develop methods for conflict mitigation and cooperation with stakeholders; iv) to integrate these components in a system for the management of natural resources. Exemplary case studies of resource use conflicts have been carried out at the Swedish west and east coast including coastal fishery, mussel culture, coastal planning and specific conflicts such as between species protection (seals) and coastal fishery. Researchers are involved as experts and as conflicting parties, and the role of scientists as stakeholders deserves special attention in conflict research. Conflict management is not only for the solution of present conflicts, but part of integrated resource management systems where knowledge transfer, institutional development, collective learning of scientific, political and administrative actors, and cooperation between scientists and resource users can occur.

HISTOACRYL BLUE VERSUS SUTURED LEFT COLONIC ANASTOMOSIS: EXPERIMENTAL STUDY

Cyanoacrylates have been advocated as a protective seal in colonic anastomosis to prevent leakage. In order to assess the effects of n-butyl-2-cyanoacrylate on left colonic anastomosis it was compared to the sutured anastomosis in the rat. Forty male Wistar albino rats were divided into two groups of 20 each. On days 3 and 7, 10 animals in each group were killed. The comparisons between n-butyl-2-cyanoacrylate and sutured groups were made with respect to outcome measures including anastomotic leakage, anastomotic stricture, peritonitis and wound infections, and adhesion formation, anastomotic bursting pressure, histological appearance of the anastomotic area. Although the adhesion formation was significantly more extensive in the n-butyl-2-cyanoacrylate group on day 3 (P < 0.001), there was no significant difference between the groups on day 7. The more inflammatory reaction also occurred in the n-butyl-2-cyanoacrylate group. The mean +/- SD anastomotic bursting pressure was significantly higher in the suture group than in the n-butyl-2-cyanoacrylate group (63 +/- 14 mmHg vs 43 +/- 8 mmHg) on day 3. The bursting pressure was also found to be higher on day 7 in the suture group (187 +/- 26 mmHg vs 49 +/- 12 mmHg, P < 0.0001). The suture group had a significantly higher bursting pressure on day 7 compared to day 3 (P < 0.05). Left colonic anastomosis with n-butyl-2-cyanoacrylate in rats does not improve the healing process; on the contrary, it has a negative influence during the first week. As a consequence, the routine use of n-butyl-2-cyanoacrylate in colonic anastomosis in the clinical situation does not appear to be justifiable.

Regional Bond Strengths of Adhesive Resins to Pulp Chamber Dentin

Microleakage of oral microorganisms, which can occur due to the lack of sealing ability of permanent restorative materials, may cause failure of root canal treatments. Although a great deal of research has been done on sealing enamel and coronal dentin with resins, little research has been done on the adhesion of resins to the walls of pulp chambers. The purpose of this study was to evaluate regional bond strengths of two adhesive systems to the walls of pulp chambers. A section was made horizontally through the middle of the pulp chamber of extracted human third molars to divide the chamber into upper and lower halves. The pulp tissue was removed and the tooth segments were then divided into treatment subgroups. The pulp chambers were bonded with C&B Metabond (Parkell) or One-Step (Bisco), with or without 5% NaOCI pretreatment. The microtensile bond strengths of these resins to four different pulp chamber regions (bottom, wall, roof, and pulp horn areas) were then measured using an Instron machine. The data were expressed in MPa and were analyzed by a three-way ANOVA. Statistically significant differences were found among the test groups (p < 0.001). One-Step produced higher bond strengths to all pulp chamber regions except the floor, compared with C&B Metabond. The results indicated that high bond strengths can be achieved between adhesive resins and the various regions of the pulp chamber. This should permit the use of a thick layer of unfilled resin along the floor of the pulp chamber and over the canal orifices as a secondary protective seal after finishing root canal therapy.

Transient Protection of Incomplete Colonic Anastomoses with Fibrin Sealant: An Experimental Study in the Rat

Fibrin glue has been used as a protective seal in normal and high-risk anastomoses to prevent leakage. The influence of fibrin adhesive on the healing colonic anastomosis in a control and high-risk model was tested. Resection and anastomosis of the left colon was performed in rats. In group Ia an end-to-end anastomosis was constructed with 12 7-O polypropylene sutures; in group Ib the anastomosis was sealed with fibrin adhesive. In group II an incomplete anastomosis was constructed with only 4 sutures at 9°, therefore potentially leaking. In group IIb additional sealing with fibrin glue was performed. On Days 2, 4, and 7 body weight, adhesion formation, anastomotic bursting pressure, and collagen concentration were measured. The results showed increased adhesion formation after fibrin sealing. The anastomotic bursting pressure of incomplete anastomoses showed a significant increase after sealing on Day 2 only; on Day 4 and 7 no differences were found. Sealing of control anastomoses caused lower bursting pressures on Day 4. Collagen concentration is significantly reduced after fibrin sealing of normal anastomoses. We conclude that fibrin sealing of control anastomoses inhibits wound healing. Incomplete anastomoses are temporarily protected by fibrin glue sealing. Finally, fibrin sealing of the colon wound does not prevent adhesion formation.

4708257 Protective seal for a can: Douglas Deline

4708257 Protective seal for a can: Douglas Deline

Effect of a contact and protective seal on aluminum electromigration

The electromigration characteristics of Al-0.5%Cu films deposited by a new Varian electron gun were evaluated. Their electromigration resistance is an order of magnitude worse than that previously reported for similarly evaporated films. Such a degradation in properties has been correlated with a more heterogenous grain structure and a loss of 〈111〉 fiber texture in the present films. An encapsulating layer partially restores the electromigration lifetimes, with the degree of improvement proportional to the mechanical rigidity of the overlying layer. Thus, a trimethylmethoxysilane contact and protective seal (CAPS) enhances conductor reliability by a factor of 2, whereas silicon nitride (SiN) increases the electromigration resistance by a factor of 9. These results suggest that the present design criterion of a d.c. current density of 1×10 5 A cm -2 in aluminum interconnects, based on data on uncovered lines, is somewhat conservative. To enhance layout density, this value may be increased to as much as 2.5×10 5 A cm -2, depending on the CAPS layer, without compromising chip reliability.

Circulation, respiration and fluid dynamics in the gastropod mollusc, Hemifusus tuba (Gmelin)

Cardiac activity, respiratory rate, and fluid movements in and out of the shell and tissues of Hemifusus tuba (Gmelin) have been investigated. Estimates of cardiac output (Q̇) were in the range 0.1 to 2.22 ml·min −1 (in individuals of 7.0 to 14.2 cm shell length). Maximum systolic ventricular pressure was between 6.4 to 11.4 cm H 2O, with highest values being recorded from large, partially-retracted specimens. Respiratory rate (V̇ 2) increased with size according to V̇ O2 α dry weight (g) −0.43. This mass exponent is low compared with that for many other species. Perfusion indices ( Q ̇ V ̇ o2 ) increased with size indicating that del was less efficient in larger Hemifusus. During retraction, two phases of fluid expulsion were recognized. The first allowed Hemifusus to retreat rapidly within the confines of its shell. The second, slower phase of retraction drew up the operculum to form a tight, protective seal with the shell. Expelled fluid, particularly from the second phase, contained blood proteins, suggesting that fluid is lost from the blood system during full retraction.

Plastic-Reinforced Asphalt Seepage Barrier

This report is concerned with laboratory equipment development, laboratory testing, and field investigations of a water seepage barrier consisting of plastic-reinforced asphalt. Three testing methods were utilized and evaluated in the asphalt-plastic-asphalt-chip-coated (APAC) membrane investigation. The first test method evaluated the hydrostatic puncture resistance of an asphalt-polyethylene combination. This test confirmed the hypothesis that the asphalt effectively increases the puncture resistance of the APAC membrane over that of plain polyethylene. The second test investigated the slope stability of a protective APAC chip seal. It was found that a typical 3/8-in. (9.5-mm) cover aggregate remained stable on constructed slopes of 3:1 and 4:1 and also remained stable on a 2:1 slope up to a surface temperature of 122°F (50°C). The third test method evaluated adhesive materials and determined the best suited adhesive for sealing polyethylene overlaps. Subsequent field investigations resulted in equipment development that increased construction efficiency in the installation of the APAC membrane.