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At least 865 records · Page 48Linked to original sources
PubMed1979

Adhesion between copper-plated acrylic tray resin and a polysulfide rubber impression material.

The method of copper plating on acrylic resin was developed, and the bond strength to polysulfide rubber was measured in comparison with that of the adhesive coating. The bond strength with copper plating was greater than with adhesive coating. The specimens with adhesive coating failed due to a rupture occurring at the elastomer-adhesive interface, while those with copper plating had cohesive-adhesive failure. The method of copper plating on acrylic resin improved the adhesion between the polysulfide rubber and the custom-built acrylic resin tray.

Acrylic Resins↗
PubMed1983

Controlling the porosity and density of silicone rubber prosthetic materials.

The chemical components of the four silicone rubber polymers were reviewed. Methods of controlling the porosity and density of both the one-component semisolid prepolymer and the two-component fluid prepolymer systems were evaluated. The variables examined were deairing of the fluid systems; trial packing, pressure sealing, and processing of the semisolid materials; injection versus hand packing of the mold; the effects of moist-heat versus dry-heat application during processing; and the need for investment of the mold within the confines of a closed flask. It can be concluded that porosity of medical-grade silicone rubber polymers may be totally prevented, or accurately controlled, by proper handling techniques.

Chemical Phenomena↗
PubMed1991

Blue rubber bleb nevus syndrome with oral hemangiomas.

A case of blue rubber bleb nevus syndrome with oral hemangiomas is reported. Attention is directed to this syndrome because, although rare, it is usually associated with oral lesions. The blue rubber bleb nevus syndrome should always be considered a possibility in patients with oral hemangiomas and bluish skin nodules.

Child↗
PubMed1990

Silicone rubber-hydrogel composites as polymeric biomaterials. II. Hydrophilicity and permeability to water-soluble low-molecular-weight compounds.

The surface and transport properties of water-swollen silicone rubber-hydrogel composites were investigated. Surface wettability of these materials, composed of a polysiloxane matrix and the hydrogel phase consisting of very fine particles of lightly cross-linked poly(2-hydroxyethylmethacrylate), increased markedly with increasing content of the hydrogel phase. For composite materials containing a lightly cross-linked 2-hydroxyethylmethacrylate (HEMA)-methacrylic acid (MAA) copolymer and polymethacrylic acid (PMAA) as the hydrogel phase, permeability to water-soluble organic compounds and drugs were measured. The permeability varied within a broad range depending on the composition and content of the hydrogel phase. High permeation rates could be obtained while still retaining relatively fair mechanical properties. Relationships between the composition of silicone rubber-hydrogel composites, their structure and the permeation coefficients of the individual permeates are discussed.

Biocompatible Materials↗
PubMed1995

Silicone rubber-hydrogel composites as polymeric biomaterials. VI. Transport properties in the water-swollen state.

Permeation of inorganic salts in water-swollen silicone rubber-hydrogel composites consisting of a silicone rubber matrix and lightly cross-linked particles of poly(2-hydroxyethyl methacrylate), poly(2-hydroxyethyl methacrylate-co-methacrylic acid), poly(methacrylic acid), polyacrylamide or poly(acrylamide-co-methacrylic acid) hydrogels was investigated. The results, together with earlier data on permeation of non-ionic low-molecular-weight substances through the composite materials, were evaluated in terms of the free-volume diffusion theory. It was found that the materials with water content exceeding a certain limit are highly permeable to the salts, and that, as regards permeation properties, they behave as homogeneous water-swollen hydrogels. The dependence of electrical conductivity of the water-swollen composites on the hydrogel phase content was measured, and the results are discussed in relation to other transport properties and to the structure of the materials.

Acrylic Resins↗
PubMed1983

A radiological study after parenteral nutrition through silicone rubber catheters: fibrin sleeves without thrombosis.

Injection of contrast material through 38 central silicone rubber catheters at the time of withdrawal after a mean catheter life of 55 days (range 5-369) has shown no evidence of occult venous thrombosis despite the presence of a fibrin sleeve around the whole length of the intravascular portion in 37 cases. The presence of this fibrin sleeve appears to have been harmless. The absence of thrombosis suggests that silicone rubber is the material of choice for central venous feeding catheters and that the addition of heparin to the infusion fluid is unnecessary.

Journal Article↗
PubMed1985

Embolisation of silicone rubber catheters used for intravenous feeding; a preventable complication.

The advantages of silicone rubber central venous catheters are widely recognised, but embolisation of the whole catheter can occur due to malfunction of the hub which is used to clamp the catheter to the female luer connector. Two cases are described in which silicone rubber catheters were successfully removed from the heart using percutaneous techniques. A modification is suggestion to prevent this complication.

Journal Article↗
PubMed1992

Silicone rubber distal ulnar replacement arthroplasty.

We retrospectively reviewed 42 patients who underwent resection of the distal ulna with implantation of a silicone rubber ulnar head prosthesis (45 wrists). Two prostheses were used: the original Swanson prosthesis, and a prosthesis of our own design. Follow-up X-rays showed migration or breakage of 63% of the prostheses. No statistically significant correlation existed between the quality of functional outcome and the integrity of the prostheses. There was no significant difference between pre-operative and post-operative range of motion for the entire group or between patients with broken or intact prostheses. Histological confirmation of silicone synovitis was documented in one patient who required implant removal. We suggest that destabilization and breakage of prostheses result from fatigue failure secondary to the torque generated at the distal radio-ulnar joint during repeated pronation and supination. Use of a silicone rubber ulnar head prosthesis following distal ulna resection is not recommended.

Adult↗
PubMed2005

Immobilization of anaerobic bacteria on rubberized-coir for psychrophilic digestion of night soil.

Low-ambient temperatures, <30 degrees C, are known to cause drastic reduction in the efficiency of anaerobic biodigesters due to low-growth rate of the constituent bacterial consortium. Immobilization of anaerobic bacteria has been attempted in the biodigester operating at 10 degrees C. Various matrices were screened and evaluated for the immobilization of bacteria in digesters. Anaerobic digestion of night soil was carried out with hydraulic retention time in the range of 9-18 days. Among the tested matrices, rubberized-coir was found to be the most useful at 10 degrees C with optimum hydraulic retention time of 15 days. Optimum amount of coir was found as 25 g/L of the working volume of biodigesters. Immobilization of bacteria on the coir was observed by scanning electron microscopy and fluorescent microscopy. The study indicates that rubberized-coir can be utilized to increase biodegradation of night soil at higher organic loading. Another advantage of using this matrix is that it is renewable and easily available in comparison to other synthetic polymeric matrices.

Journal Article↗
PubMed2005

An ergonomic evaluation of manual Cleco plier designs: effects of rubber grip, spring recoil, and worksurface angle.

The present study evaluated two design modifications (rubber grip and torsion spring) to the conventional manual Cleco pliers by electromyography (EMG), hand discomfort, and design satisfaction. This study also surveyed workers' satisfaction with selected design features of the pliers for ergonomic improvement. A two-way (plier design x worksurface angle) within-subject (nested within gender and hand size) design was employed. Eleven workers simulated the plier task in an adjustable workstation for different plier designs and worksurface angles (0 degrees , 60 degrees , and 90 degrees ). Lower EMG values were obtained for the pliers with rubber grip and at 60 degrees of worksurface angle. EMG values varied significantly between the participants, but showed low correlations (Spearman's rank correlation = -0.27 approximately -0.58) with their work experience with the pliers. The hand discomfort and design satisfaction evaluations identified that the grip span (max = 14.0 cm) and grip force requirement (peak = 220.5 N) of the current pliers need ergonomic modification. The present study shows the needs of both the ergonomic design of a hand tool and the training of a proper work method to control work-related musculoskeletal disorders at the workplace.

Adult↗
PubMed2004

Effects of sample hardness on human chewing force: a model study using silicone rubber.

This study aims to clarify the effects of sample hardness on chewing force of humans. Silicone rubber was chosen as a food model, and three silicone rubber samples of varying hardness were chewed between the upper and lower incisors or molars in a natural way. Chewing force, contact area between a specimen and teeth, and pressure applied into the specimen were dynamically measured with a multiple-point sheet sensor. The multiple-point measurement revealed that a harder sample evoked higher peak force, longer duration, higher impulse, and higher active pressure values, whereas the chewing cycle and time to peak were not affected by sample hardness. The contact area between the sample and teeth decreased for the harder sample during incisor chewing. The peak force and force-related parameters, contact area, time to peak and bite force duration showed higher values for molar bites than for incisor bites, while the chewing cycle was similar in both cases. The measurement with the sheet sensor system clearly indicated that sample hardness modified chewing force of humans. We hypothesise that the effect of sample hardness is mainly mediated by mechanoreceptors in the periodontal ligament.

Adult↗
PubMed2005

Platelet adhesion and protein adsorption on silicone rubber surface by ozone-induced grafted polymerization with carboxybetaine monomer.

Platelet adhesion and protein adsorption on the silicone rubber film grafted with N,N'-dimethyl-N-methacryloyloxyethyl-N-(2-carboxyethyl) ammonium (DMMCA) was studied. The grafting was carried out by means of ozone-induced method and was confirmed by ATR-FTIR and XPS investigations. The grafted films possessed relatively hydrophilic surface revealed by contact angle measurement. The blood compatibility of the grafted film was evaluated in vitro by platelet adhesion in platelet-rich plasma (PRP) and protein absorption in bovine fibrinogen (BFG) using silicone film as the reference. No substantial platelet adhesion was observed for the grafted films incubated in PRP for 60 and 180 min. The protein absorption was also significantly reduced after incubated in bovine fibrinogen for 60 min. Both the results indicated that the blood compatibility of silicone rubber was greatly improved by ozone-induced grafting of carboxybetaine zwitterionic polymer onto its surface.

Animals↗
PubMed2006

Purification and characterization of cassiicolin, the toxin produced by Corynespora cassiicola, causal agent of the leaf fall disease of rubber tree.

Cassiicolin, a phytotoxin produced by the necrotrophic fungus Corynespora cassiicola, was purified to homogeneity from a rubber tree isolate. The optimized protocol involves reverse phase chromatography followed by size exclusion chromatography, with monitoring of the toxicity on detached rubber tree leaves. Cassiicolin appeared to be a peptide composed of 27 amino acids, glycosylated on the second residue, with a N-terminal pyroglutamic acid and 6 cysteines involved in disulfide bonds. Its molecular mass was estimated to be 2885 Da. No significant sequence homology with other proteins could be found. The availability of pure toxin in sufficient amount is a prerequisite for its structure determination, which is a key step in the understanding of the aggression mechanism.

Amino Acid Sequence↗
PubMedDate not supplied

Transcystic cholangiogram access via rubber band with early withdrawal after liver transplantation: a safe technique.

OBJECTIVE: Since different techniques have been described for cholangiogram access after liver transplantation, we compared two different methods for patients with duct-to-duct biliary anastomoses. METHODS: Adult liver transplant patients from program inception in 1993 to May 2003 in whom a duct-to-duct biliary anastomosis with a T-tube choledochostomy were compared with those having a transcystic duct catheter using a rubber band. We excluded 10 patients in which a different technique was used or graft or patient survived less than 21 days. Group A (n = 28,) had a number 10 T-tube exteriorized through the recipient main bile duct; and group B (n = 33) a number 5 Bard ureteral stent tied to the cystic stump with reabsorbable suture and secured with a hemorrhoidal rubber ligature. RESULTS: The biliary complication rate was lower among the transcystic catheter group (9.1%, 3/33) compared to the T-tube group (35.7%, 10/28). Postcatheter withdrawal peritonitis was present in two patients in the T-tube group, one of whom required emergency laparotomy. A satisfactory postoperative cholangiogram was obtained in both groups. The transcystic catheter was withdrawn on average at 29 days, compared to 136 days in the T-tube group. CONCLUSIONS: Both techniques are equally effective in obtaining a satisfactory postoperative cholangiogram. However, the transcystic catheter technique allows a significantly earlier withdrawal with fewer complications compared to the T-tube technique.

Adult↗
PubMed2001

Intermittent visual loss and exophthalmos due to the Blue rubber bleb nevus syndrome.

PURPOSE: To describe the occurrence of intermittent visual loss in a patient with orbital hemangioma due to the blue rubber bleb nevus syndrome. METHODS: Case report. RESULTS: A 70-year-old woman complained of intermittent blurred vision combined with pressure behind her left eye occurring after head bending or Valsalva maneuvers. Examination revealed 2 mm of enophthalmos on the left. After downward bending of the head the eye became exophthalmic by 12 mm and visual acuity decreased to finger counting. Neuro-ophthalmologic examination was otherwise normal. Magnetic resonance imaging revealed an intraconal hemangioma. Bluish, soft, rubber-like, compressible and slowly refilling hemangiomas on the inferior lip, sublingually, on the hand, and vagina led to the diagnosis of BRBNS. CONCLUSIONS: Intermittent visual loss may be the presenting symptom of an orbital hemangioma in BRBNS. Recognition of this rare condition is important because of its potentially life-threatening complications.

Aged↗
PubMed1981

Use of silicone rubber to facilitate shunt takedown.

The takedown of systemic-pulmonary artery shunts at the time of corrective operation is time-consuming and potentially dangerous because of adhesions at the previous operative site. A method of facilitating shunt takedown is described in which a strip of silicone rubber is used to surround the subclavian artery or polytetrafluoroethylene graft interposed between the subclavian artery and the pulmonary artery. The ends of the strip are left loosely attached to the anterior mediastinum so that an adhesion-free plane is left between the strips down to the shunt. The experience of the Yale University School of Medicine with this technique in 14 patients is described. Five underwent reoperation, at which time the silicone rubber strip facilitated access to the shunt and shunt takedown.

Blood Vessel Prosthesis↗
PubMed1977

Silicone rubber band for laparoscopic tubal sterilization.

In 1974, Yoon and associates (Am J Obstet Gynecol 120:132, 1974) described a new approach in which laparoscopic tubal occlusion was accomplished by utilizing the silicone rubber band technique. Recognizing the great advantages of the new technique in eliminating potential thermal injury associated with electrocoagulation, the authors have utilized the Yoon silicone rubber band technique in these institutions over the past 20 months. Thus far the procedure has been performed in 304 patients without any major complications. In the hope of eliminating and/or reducing possible pregnancy-failure rates, in 110 cases. In addition to application of the silicone band, the tube within the band was transected with non-electrical Seigler biopsy forceps. This, we believe, should provide an interesting long-term comparative study.

Female↗
PubMed1995

Randomized, prospective study of cyanoacrylate injection, sclerotherapy, or rubber band ligation for endoscopic hemostasis of bleeding canine gastric varices.

The purpose of this randomized, nonblinded study was to compare the effectiveness, safety, and technical ease of three different endoscopic techniques for the treatment of bleeding gastric varices in a canine model. Twenty dogs with large, bleeding gastric varices underwent endoscopic hemostasis with rubber band ligation, sclerotherapy, and cyanoacrylate injection. The time and number of attempts required to achieve definitive hemostasis were evaluated for each technique, and each method was assessed for ease of use. Ulceration rates, ulcer size and depth, and stigmata of ulcer hemorrhage were assessed at 1 week. Intravariceal sclerotherapy was the fastest and easiest to perform. Rubber band ligation was intermediate in technical ease, but it caused the largest and deepest ulcers and had the highest rates of stigmata of ulcer hemorrhage and secondary bleeding. Cyanoacrylate injection was the most cumbersome endoscopic method to perform. All three treatments were effective for controlling gastric variceal bleeding. Intravariceal sclerotherapy had the most favorable results overall because of its technical ease, efficacy, and modest complication rates.

Animals↗