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PubMed1988

[2 cases of early "siliconitis" (silicone synovitis)].

Two cases of early silicone synovitis, 12 and 18 months after surgery for partial scaphoid implant arthroplasty (Swanson design) are reported. None of the implants had been fixed by Kirschner wire or sutured to the radius or an other carpal bone. Both implants had been immobilized for six weeks. Initially the result in both cases was good. Pain and loss of range of movement gradually increased, and a large erosive osteolytic defect of the radius was seen on the X-ray after 12 months for the first case and 18 months for the second one. Surgical revision consisted of implant removal, synovectomy with a proximal row carpectomy in the first case and a soft tissue interposition arthroplasty for the second one. The histologic examination showed a foreign body reaction with birefringent material in multinucleated giant cells. All reports about this type of silicone implant complication emphasises the role of compression forces and micro-fragmentation of the silicone. Should we continue to perform partial scaphoid implant arthroplasty from whom microparticles are creating a severe foreign body reaction?

Adult↗
PubMed2002

Design and implementation of new, silicon-based, cross-coupling reactions: importance of silicon-oxygen bonds.

This Account chronicles the conceptual development, proof of principle, exploration of scope, and mechanistic investigations of a newly developed class of palladium-catalyzed cross-coupling reactions of silicon derivatives. Under the influence of fluoride activation a myriad of oxygen-containing silicon moieties undergo mild and stereospecific cross-coupling. The diversity of methods for introduction of silicon groupings into organic molecules and the range of organic electrophiles that can be used are outlined.

Catalysis↗
PubMed1993

Removal of silicone oil in the management of glaucoma in eyes with emulsified silicone.

Glaucoma and emulsification are two complications of silicone oil injection that are often coexisting. This study was undertaken to determine whether removal of emulsified oil has any effect on the management of the glaucoma. A comparison of eyes with and without glaucoma with emulsified oil also was undertaken. Eighteen eyes that underwent removal of emulsified silicone oil more than 6 months after the injection of the oil were reviewed. All eyes were observed for at least 6 months after removal with attached retinas. Eleven eyes had glaucoma at the time of removal. The diagnosis of glaucoma preceded the identification of emulsification in 8 of 11 eyes (73%). Removal of the emulsified oil did not affect the intraocular pressure (IOP) in 10 of the 11 (91%) glaucomatous eyes. The IOP was reduced in one patient. In the glaucoma patients, the final visual acuity was significantly reduced compared with the best corrected visual acuity obtained during the follow-up period (P = 0.016). In the nonglaucoma eyes with emulsified oil, the visual acuity did not significantly deteriorate during follow-up. At the end of the follow-up period, optic atrophy was observed in 9 of 11 (82%) of the eyes with glaucoma compared with two of seven (28%) of eyes without glaucoma. The results suggest that removal of emulsified silicone oil failed to control the glaucoma, and could not change the aggressive nature of the glaucoma in these eyes.

Adult↗
PubMed1987

Silicone oil removal. I. The effect on the complications of silicone oil.

The results of a retrospective study of the effects of silicone oil removal from 85 eyes in 85 patients are reported. Pars plana vitrectomy and fluid/silicone oil exchange had been undertaken for retinal detachments associated with giant retinal tears or with proliferative vitreoretinopathy in all cases. Clinically significant cataract developed in 60% of lenses that were clear at the time of oil removal, and 85% of pre-existing lens opacities progressed. Removal of oil from 19 eyes with uncontrollable glaucoma was combined with drainage surgery in 14 eyes. Postoperatively the intraocular pressure was controlled in 13. Corneal decompensation either improved or was unchanged in eight out of nine patients after silicone oil removal, and three patients had penetrating keratoplasty and maintained a clear corneal graft. Patients who did not have glaucoma or keratopathy at the time of silicone oil removal did not develop these complications.

Cataract↗
PubMed1998

Clinical and scintigraphic comparison of silicone and polyvinylpyrrolidone coated silicone perforated plugs.

BACKGROUND/AIM: Isolated stenosis of the lacrimal punctum is a frequent cause of epiphora. Treatment relies on surgical opening or dilatation with bi- or monocanalicular prosthesis. Recently, silicone perforated punctum plugs (PPP) were proposed. The drawback with these silicone PPP was that secretions accumulate in the central orifice blocking the spontaneous flow of tears. A modification of the surface of the PPP using polyvinylpyrrolidone (PVP) was thus proposed. The aim was to compare silicone PPP with new PVP surface treated PPP. METHODS: A prospective study was conducted of 20 patients with dilatable stenosis of the lacrimal puncta who developed epiphora. Epiphora, tolerance, implantation of the PPP, and lacrimal drainage were evaluated using scintigraphy of the lacrimal ducts. RESULTS: The raw data and statistical analysis showed evidence of a superior performance of PVP surface treated PPP. CONCLUSION: Long term evaluation of the advantages or risks of PVP plugs and comparison with microsurgical punctoplasty are warranted.

Drainage↗
PubMedDate not supplied

Endoscopically assisted balloon dacryocystoplasty and silicone intubation versus silicone intubation alone in adults.

PURPOSE: To compare the success rate of endoscopically assisted balloon dacryocystoplasty (DCP) and silicone intubation (DCP-SI) with endoscopically assisted silicone intubation alone (SI) in adults with incomplete nasolacrimal duct (NLD) obstruction. METHODS. In a retrospective nonrandomized comparative case series, 62 eyes of 55 adult patients with incomplete NLD obstruction underwent endoscopic probing and either SI (n=39 eyes) or DCP-SI (n=23 eyes) under general anesthesia. The last follow-up examination included diagnostic probing and irrigation if there was not success. Success was defined as disappearance of the symptoms and failure as partial improvement or absence of improvement at last follow-up. RESULTS: Patients ranged from 20 to 85 years of age (mean: 60.93, SD: 15.60). Tubes were removed between 6 and 20 weeks (mean: 7.49, SD: 2.25) postoperatively. Follow-up ranged from 6 to 63 months (mean: 14.60, SD: 10.33). Success rate of the eyes with SI (21/39, 53.84%) and DCP-SI (14/23, 60.86%) were not statistically different (p=0.60). Complications included slight nasal and canalicular bleeding in almost all eyes in both groups which was easily controlled, slit punctum in four eyes with bicanalicular intubation (4/50, 8%), and monocanalicular tube lost in three eyes prematurely. CONCLUSIONS: Success rate of endoscopic DCP-SI had no statistically significant difference from silicone intubation alone in treatment of incomplete NLD obstruction in adults.

Adult↗
PubMed1993

The effects of venous blood, silicone gel and prilocaine on capsular contraction around silicone implants studied with a new method in the rat.

The pressure exerted by wound tissue on a subcutaneously implanted silicone expander was studied in rats. A significant increase in pressure was noted four and eight weeks postoperatively when venous blood was instilled into the cavity around the expander, but this increase was significantly reduced at eight weeks if 1.0 ml of prilocaine 5 mg/ml with adrenaline 4 micrograms/ml was instilled at the same time as the blood. Instillation of silicone gel outside the expander tended to increase the pressure eight weeks postoperatively, but there was no increase when silicone gel was given together with prilocaine and adrenaline. The next step is to investigate whether prilocaine with adrenaline instilled around an implanted mammary prosthesis in humans is not only capable of reducing pain and bleeding but can also inhibit capsular contracture.

Animals↗
PubMed1991

Silicone gel-filled breast prostheses; silicone inflatable breast prostheses: patient risk information--FDA. Notice.

The Food and Drug Administration (FDA) is issuing a notice to promote the dissemination of information on risks associated with silicone gel-filled breast prostheses and silicone inflatable ("saline-filled") breast prostheses to women considering having the devices implanted. This notice addresses an important public health issue presented by the continued marketing and implantation of these unapproved devices. FDA has identified significant deficiencies in premarket approval applications for silicone gel-filled breast prostheses. FDA will regard breast prostheses as misbranded under the Federal Food, Drug, and Cosmetic Act (the act) if their labeling does not provide adequate written information to patients on the risks associated with these devices. Such information should be written so as to be easily comprehensible to most patients and should be provided to patients prior to scheduling implantation, so that patients have sufficient time to review the information and discuss it with their physicians. To satisfy the requirements of the act, such patient risk information must set out the known, suspected, and potential risks associated with implantation of these devices. This notice includes suggested patient risk information sheets as guidance.

Female↗
PubMed2001

Overstoichiometric low-energy nitrogen implantations into silicon--formation of gas nanobubbles vs. silicon nanowhiskers.

Accelerator-based ion implantation can be used to produce stoichiometric ratios beyond thermodynamic equilibrium. In the studies reported here, single crystalline silicon wafer material was implanted with high fluences of nitrogen. The implantations, performed with 15N at 5 keV/ion, resulted in the formation of highly swollen nitrogen rich surfaces that incorporated up to 63 at.% nitrogen. The implanted specimens were subsequently annealed with electron beams at high temperature, typically 1150 degrees C for moderately short periods of time (15 s) to investigate the formation of silicon nanowhiskers. However, it was observed that nanowhiskers, the formation of which can be expected by comparable understoichiometric implantations, did not appear. Although the shallow implantations created ultrathin silicon nitride films with typical thickness of 25 nm, laterally swollen areas of 400 +/- 50 nm were observed with atomic force microscopy operated in supersonic mode.

Crystallization↗
PubMedDate not supplied

Nanotribological effects of silicone type, silicone deposition level, and surfactant type on human hair using atomic force microscopy.

The atomic/friction force microscope (AFM/FFM) has recently become an important tool for studying the micro/nanoscale structure and tribological properties of human hair. Of particular interest to hair and beauty care science is how common hair-care materials, such as conditioner, deposit onto and change hair's tribological properties, since these properties are closely tied to product performance. Since a conditioner is a complex network of many different ingredients (including silicones for lubrication and cationic surfactants for static control and gel network formulation), studying the effects of these individual components can give insight into the significance each has on hair properties. In this study, AFM/FFM is used to conduct nanotribological studies of surface roughness, friction force, and adhesive forces as a function of silicone type, silicone deposition level, and cationic surfactant type. Changes in the coefficient of friction as a result of soaking hair in de-ionized water are also discussed.

Adhesiveness↗
PubMed1990

Reactions at silicone-injected sites on the face associated with silicone breast implant "inflammation" or "rejection".

Although complications in various parts of the body have been suggested as being produced when silicone mammary implants are "rejected" or produce inflammation, there have apparently been no reports describing "flares" at previous sites of facial silicone injections as complications of mammary silicone implants. Such reactions appear to be comparable to so-called "systemic contact dermatitis." However, in the absence of results of skin testing, the mechanism of such "ectopic" flares remains in doubt.

Breast↗
PubMed1986

Silicone synovitis following silicone implant arthroplasty.

Silicone synovitis is a late complication of silicone implant arthroplasty. The problem is usually heralded by pain and limitation of motion caused by synovitis and bone destruction. Once silicone synovitis develops, secondary procedures include removal of the implant, synovectomy, and reconstructive surgery individualized to the patient's pathology.

Carpal Bones↗
PubMed2006

Silicon radicals in silicon oxynitride: a theoretical ESR study.

Quantum mechanical calculations are performed on a series of silicon radical defects. These are the upward arrow Si[triple bond]O(3-x)Nx, upward arrow Si[triple bond]N(3-x)Si(x), and upward arrow Si[triple bond]Si(3-x)Ox defects, where x takes on values between 0 and 3. The defects under study constitute a central silicon radical, upward arrow Si, with differing first-nearest-neighbor substitution, as may be found at a Si/SiOxNy interface. These first-nearest neighbor atoms are connected to the silicon radical via three single covalent bonds, denoted as " [triple bond] ". A hybrid defect, upward arrow Si[triple bond]ONSi, is also included. Calculations are performed on gas-phase-like cluster models, as well as more-constrained hybrid quantum and molecular mechanical (QM/MM) models. The isotropic hyperfine coupling constants of these defects are calculated via density functional theory (DFT). Trends in these calculated hyperfines are consistent between the different models utilized. Analysis of the electronic structure and geometries of defects correlate well with trends in the electronegativity of the first-nearest-neighbor atoms. Changes in radical hybridization, induced by changes in the first-nearest-neighbor composition, are the primary factor that affects the calculated hyperfines. Furthermore, comparisons to experimental results are encouraging. Agreement is found between experiments on amorphous to crystalline materials.

Journal Article↗
PubMed2002

Preparation of porous n-type silicon sample plates for desorption/ionization on silicon mass spectrometry (DIOS-MS).

This study focuses on porous silicon (pSi) fabrication methods and properties for desorption ionization on silicon mass spectrometry (DIOS-MS). PSi was prepared using electrochemical etching of n-type silicon in HF-ethanol solution. Porous areas were defined by a double-sided illumination arrangement: front-side porous areas were masked by a stencil mask, eliminating the need for standard photolithography, and backside illumination was used for the backside ohmic contact. Backside illumination improved the uniformity of the porosified areas. Porosification conditions, surface derivatizations and storage conditions were explored to optimize pSi area, pore size and pore depth. Chemical derivatization of the pSi surfaces improved the DIOS-MS performance providing better ionization efficiency and signal stability with lower laser energy. Droplet spreading and drying patterns on pSi were also examined. Pore sizes of 50-200 nm were found to be optimal for droplet evaporation and pore filling with the sample liquid, as measured by DIOS efficiency. With DIOS, significantly better detection sensitivity was obtained (e.g. 150 fmol for midazolam) than with desorption ionization from a standard MALDI steel plate without matrix addition (30 pmol for midazolam). Also the noise that disturbs the detection of low-molecular weight compounds at m/z < 500 with MALDI could be clearly reduced with DIOS. Low background MS spectra and good detection sensitivity at the 100-150 fmol level for pharmaceutical compounds were achieved with DIOS-MS.

Journal Article↗
PubMed2003

Direct synthesis of aligned silicon carbide nanowires from the silicon substrates.

Aligned silicon carbide nanowires were synthesized directly from the silicon substrates via a novel catalytic reaction with a methane-hydrogen mixture at 1,100 degrees C, with a mean diameter of 40 nm and length of 500 microm; they consist of a single-crystalline zinc blende structure crystal in the [111] growth direction; X-ray diffraction, Raman, and infrared spectroscopy confirm the synthesis of high-purity silicon carbide nanowires.

Journal Article↗
PubMed2005

Silicon-based nanowires from silicon wafers catalyzed by cobalt nanoparticles in a hydrogen environment.

We present here the synthesis of silicon-based nanowires directly from silicon wafers at high temperatures and in the presence of cobalt nanoparticles and hydrogen gas. All three ingredients were critical to the growth of Si-based nanowires, which were between 5-60 nm in diameter and microm-mm long. Both heavily coiled and straight Si-based nanowires were made. Experimental evidence suggested that the sources of silicon for the nanowires growth were in the gas phase.

Journal Article↗
PubMed2003

The effects of silicone fluid additives and silicone elastomer matrices on barnacle adhesion strength.

Barnacle adhesion strength was used to screen seventy-seven polydimethylsiloxane elastomeric coatings for fouling-release properties. The test coatings were designed to investigate the effect on barnacle adhesion strength of silicone fluid additive type, additive location, additive molecular weight, additive loading level, mixtures of additives, coating matrix type and coating fillers. The type of silicone fluid additive was the primary controlling factor in barnacle fouling-release. The type of silicone matrix in which the fluid resided was found to alter the effect on fouling-release. Two PDMS fluids, DMSC15 and DBE224, significantly reduced the adhesion strength of barnacles compared to unmodified elastomers. Optimum fouling-release performance was dependent on the interaction of fluid type and elastomeric matrix.

Adhesiveness↗