Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Steel”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2006

Comparative corrosion study of "Ni-free" austenitic stainless steels in view of medical applications.

The role of nickel in the biological response to alloys used in medical devices is of immense significance with regard to toxicology and biological performance. There is now a tendency to take nickel out of alloys for medical applications. However, this needs careful evaluation since no compromise is acceptable with regard to mechanical properties, corrosion resistance or any other harmful consequences due to the nickel substitution. This paper analyses the corrosion behaviour and cations released for five austenitic steels, nominally "nickel-free". The analysis of electrochemical parameters, open circuit potential, polarisation resistance, Tafel slopes, corrosion current, breakdown potential, potentiodynamic polarisation curves, and coulometric analysis by zone, reveal that the new austenitic steels, nominally "nickel-free", do not behave in the same way. In the family of steels studied, quite a large dispersion is noted in the corrosion behaviour. With regard to the crevice corrosion behaviour, the steel grades studied can be classified into three groups, with crevice potentials of 600-650mV; 350-450mV and 100-150mV. The release of 18 cations (Al, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, P, Pb, Sn, Sr, Ti, and V) was studied by extraction tests in artificial sweat and bone plasma fluid. The extraction tests reveal that the "nickel-free" steels indeed release only faint traces of nickel. Yet many other elements, some of them potentially harmful, are released in significant amounts. Generally, the amount of cations released is substantially higher in the artificial sweat solution than in the bone plasma.

Alloys↗
PubMed2005

Prospective randomized comparison of early and late results of a carbonized stent versus a high-grade stainless steel stent of identical design: the PREVENT Trial [corrected].

BACKGROUND: Restenosis after coronary interventions with stent implantation is still the main obstacle of interventional cardiology. The aim of this study was to compare a carbonized and high-grade stainless steel stent of identical design with regard to early and late adverse events. METHODS: In this prospective randomized trial the carbonized MAC stent (amg GmbH, Raesfeld-Erle, Germany) was compared with the stainless steel MAC stent of identical design. Primary end point was diameter stenosis at follow-up; secondary end points were angiographic parameters, rate of restenosis, and major cardiac adverse events (MACE; myocardial infarction, reintervention, and death). RESULTS: Between August 1999 and June 2002, 396 patients were randomized in 2 centers of Germany. Diameter stenosis at follow-up (38.6% +/- 23.4% vs 39.1% +/- 22.2%, P = .49) as primary end point, relative late lumen loss (26.8% +/- 23.7% vs 27.7% +/- 22.3%, P = .26), absolute late lumen loss (0.92 +/- 0.71 vs 0.92 +/- 0.66 mm, P = .58), net gain (1.4 +/- 0.8 vs 1.4 +/- 0.8 mm, P = .96), as well as restenosis rates (18.0% vs 19.0%, P = .81) and MACE (13.5% vs 12.2%, P = .71) were not significantly different between the carbonized and the pure stainless steel study arm, respectively. CONCLUSION: The hypothesis of superiority of the carbonized stent over a stainless steel stent of identical design with regard to restenosis and MACE could not be proved. Inactive coating of stents seems to have no advantage over pure stainless steel stents, which was also demonstrated in other trials. The future probably lies in active coating of stents with drugs that reduce the neointimal proliferation process.

Adult↗
PubMed2005

Electric block current induced detachment from surgical stainless steel and decreased viability of Staphylococcus epidermidis.

In vitro studies investigating the influence of electric DC current on bacterial detachment have demonstrated that continuous currents of only 25-125 microA stimulated staphylococcal strains to detach from surgical stainless steel. However, DC currents produce more power that has to be dissipated by the skin as compared to alternating currents. Also, an excess of ions on the steel can cause negative osteogenesis and fixation results. Therefore, it is the aim of this paper to examine whether detachment of Staphylococcus epidermidis from stainless steel surfaces in a parallel plate flow chamber can also be stimulated using electric block currents. Block currents of 15, 60 and 100 microA with different frequencies (0.1-2 Hz) and duty cycles (5-50%) were applied to induce bacterial detachment. Block currents of 100 microA cause detachment of about 76% of adhering staphylococci from stainless steel, whereas in addition the remaining bacteria are less viable, as determined by culturing the remaining bacteria on agar plates. Therewith, block current-induced detachment of adhering bacteria from stainless steel appears to be an equally promising method to prevent infection of orthopaedic fixation pins and screws than application of DC currents.

Adsorption↗
PubMed2006

Distribution of lead in urban roadway grit and its association with elevated steel structures.

In an effort to determine the source of exterior lead contamination, we investigated the concentration of lead in roadway grit along major thoroughfares in New York City and in certain areas under elevated steel structures supporting elevated rails. Such structures represent only one source of lead in roadway grit. While data revealed that the median lead concentration in roadway grit did not exceed the standard for a lead hazard in bare residential soil in any borough, the limit of 400 microg/g was exceeded 22%, 18%, 10.5%, and 7.7% of the time in Manhattan, Brooklyn, The Bronx, and Queens, respectively. The second part of the study revealed the presence of high concentrations of lead in roadway grit directly under elevated steel structures. The differences in the concentration of lead in roadway grit under steel structures in comparison to areas in NYC not near elevated rails was statistically significant. Of the eight sites studied from 225 total samples, the median roadway grit lead level was 340 ppm, while the level under steel structures was 1480 ppm. Preliminary efforts to determine particle size distribution revealed that 84% of the particles were in the range of 125-500 microm, but the highest concentration of lead was in the smallest fraction analyzed (<63 microm). Lead contamination of roadway grit from restoration of elevated painted steel structures is a public health problem as these lead particulates get re-suspended in the ambient environment and are wafted and tracked into residences.

Air Pollutants↗
PubMed2003

The kinetics of removal of proteins adsorbed on a stainless steel surface by H2O2-electrolysis and factors affecting its performance.

The kinetics of the removal of beta-lactoglobulin (beta-Lg) adsorbed on a stainless steel surface by H(2)O(2)-electrolysis treatment, in which hydroxyl radicals (.OHs) generated by the electrolysis of hydrogen peroxide decompose the substances adhering on the surface, was investigated. The rate of removal of the adsorbed beta-Lg from the stainless steel surface during the treatment was monitored in situ by ellipsometry. The dependencies of the removal rate on the H(2)O(2) concentration, the electric potential applied to the surface, and the supporting electrolyte concentration were examined and the results were compared with those obtained for the treatment of a titanium surface. Differences in the removal rates of the protein from the stainless steel and titanium surfaces are discussed with respect to differences in the nature of the interaction between the protein and the surface. The atomic compositions of the stainless steel surface before and after treatment were analyzed by Auger electron spectroscopy, and the stainless steel surface was found not to be affected by the H(2)O(2)-electrolysis treatment. The influences of various coexisting materials on removal characteristics during the H(2)O(2)-electrolysis treatment were also investigated. The difference between the effect of coexisting substances on the decomposition rate for the radical reaction in the H(2)O(2)-electrolysis treatment and that for the well-known UV-H(2)O(2) treatment in bulk solution is discussed.

Adsorption↗
PubMed1999

Comparison of cutting efficiency and instrumentation of curved canals with nickel-titanium and stainless-steel instruments.

The cutting efficiency and the effects of instrumentation on curved canal shape of both stainless-steel and nickel-titanium nonstandardized ProFile Series 29 hand instruments and stainless-steel Flexoreamer were investigated under standardized conditions. Concerning cutting efficiency in rotary motion, the Flexoreamer had significantly (p < 0.01) greater cutting efficiency than stainless-steel ProFiles and nickel-titanium ProFiles. Changes in the canal shape differed significantly between the different instruments at all measuring points (p < 0.001). After instrumentation with Flexoreamers with inclusion of two half-sizes (#17 and #22), there were fewer undesirable changes in canal shape compared with both stainless-steel and nickel-titanium ProFile Series 29 instruments. In this study, it seemed that flexible stainless-steel instruments with noncutting tips were superior to the nonstandardized ProFile Series 29 instruments with regard to cutting efficiency and instrumentation of curved canals.

Analysis of Variance↗
PubMed2004

Characterization of airborne and bulk particulate from iron and steel manufacturing facilities.

Characterization of airborne and bulk particulate material from iron and steel manufacturing facilities, commonly referred to as kish, indicated graphite flakes and graphite flakes associated with spherical iron oxide particles were unique particle characteristics useful in identifying particle emissions from iron and steel manufacturing. Characterization of airborne particulate material collected in receptor areas was consistent with multiple atmospheric release events of kish particles from the local iron and steel facilities into neighboring residential areas. Kish particles deposited in nearby residential areas included an abundance of graphite flakes, tens of micrometers to millimeters in size, and spherical iron oxide particles, submicrometer to tens of micrometers in size. Bulk kish from local iron and steel facilities contained an abundance of similar particles. Approximately 60% of blast furnace kish by volume consisted of spherical iron oxide particles in the respirable size range. Basic oxygen furnace kish contained percent levels of strongly alkaline components such as calcium hydroxide. In addition, concentrations of respirable Mn in airborne particulate in residential areas and at local iron and steel facilities were approximately 1.6 and 53 times the inhalation reference concentration of 0.05 microg/m3 for chronic inhalation exposure of Mn, respectively. Thus, airborne release of kish may pose potential respirable particulate, corrosive, or toxic hazards for human health and/or a corrosive hazard for property and the environment.

Air Pollutants↗
PubMed2001

The growth of Bacillus stearothermophilus on stainless steel.

AIMS: To determine the potential for Bacillus stearothermophilus cells to form biofilms of significance in dairy manufacture. METHODS AND RESULTS: The ability of isolates of B. stearothermophilus from dairy manufacturing plants to attach to stainless steel surfaces was demonstrated by exposing stainless steel samples to suspensions of spores or vegetative cells and determining the numbers attaching using impedance microbiology. Spores attached more readily than vegetative cells. The attachment of cells to stainless steel was increased 10-100-fold by the presence of milk fouling the stainless steel. The growth of B. stearothermophilus as a biofilm on stainless steel surfaces was determined using a continuously flowing experimental reactor. Vegetative cells were released in greater numbers than spores from biofilms of most strains studied. Biofilms of one strain (B11) were studied in detail. Biofilms of > 106 cells cm-2 formed in the reactor and released approximately 106 cells ml-1 into milk passing over the biofilm. A doubling time of 25 min was calculated for this organism grown as a biofilm. CONCLUSION: The formation of biofilms of thermophilic Bacillus species within the plant appears to be a likely cause of contamination of manufactured dairy products. Methods to control the formation of biofilms in dairy manufacturing plants are required to reduce the contamination of dairy products with thermophilic bacilli. SIGNIFICANCE AND IMPACT OF THE STUDY: Biofilms of B. stearothermophilus growing in dairy manufacturing plants can explain the contamination of dairy products with these bacteria.

Bacterial Adhesion↗
PubMed2002

Comparison of adhesion of the food spoilage bacterium Shewanella putrefaciens to stainless steel and silver surfaces.

AIMS: To compare the number of attached Shewanella putrefaciens on stainless steel with different silver surfaces, thus evaluating whether silver surfaces could contribute to a higher hygienic status in the food industry. METHODS AND RESULTS: Bacterial adhesion to three types of silver surface (new silver, tarnished silver and sulphide-treated silver) was compared with adhesion to stainless steel (AISI 316) using the Malthus indirect conductance method to estimate the number of cfu cm(-2). The number of attached bacteria on new silver surfaces was lower than on steel for samples taken after 24 h. However, this was not statistically significant (P > 0.05). The numbers of attached bacteria were consistently lower when tarnished silver surfaces were compared with stainless steel and some, but not all, experiments showed statistical significance (P < 0.05). Treating new silver with sulphide to reproduce a tarnished silver surface did not result in a similar lowering of adhering cells when compared with steel (P > 0.05). CONCLUSIONS: New or tarnished silver surfaces caused a slight reduction in numbers of attached bacteria; however, the difference was only sometimes statistically significant. SIGNIFICANCE AND IMPACT OF THE STUDY: The lack of reproducibility in differences in numbers adhering to the different surfaces and lack of statistical significance between numbers of adhered viable bacteria do not indicate that the tested silver surfaces can be used to improve hygienic characteristics of surfaces in the food industry.

Bacterial Adhesion↗
PubMed2000

A comparison of stainless steel and nickel-titanium H-type instruments of identical design: torsional and bending tests.

OBJECTIVE: For a true comparison of clinically relevant qualities of instruments manufactured from different alloys, the instrument must be identical in design. The purpose of this study was to perform mechanical tests on stainless steel and nickel-titanium instruments of identical design. STUDY DESIGN: Identical experimental endodontic files of H-type with double helix were fabricated from stainless steel and nickel-titanium alloys. Torsional and bending tests were carried out according to American National Standards Institute/American Dental Association specification No. 58 and International Standards Organization No. 3630/1. Changes in instruments during the testing were also analyzed with scanning electron microscope technique. RESULTS: The results indicated that the torsional moment of the stainless steel files was significantly higher than for the nickel-titanium files (P <.001), whereas the mean angular deflection for the nickel-titanium files was significantly higher. The mean bending moment for the nickel-titanium files was significantly lower (P <.001) than the mean value for the stainless steel files. The scanning electron microscope demonstrated that the fracture surfaces of the stainless steel files were brittle, whereas the nickel-titanium files had a ductile fracture. CONCLUSIONS: When the design of endodontic instruments of different alloys is identical, the nickel-titanium files are more flexible in bending. However, nickel-titanium files require less force to deform to fracture.

Dental Alloys↗
PubMedDate not supplied

Occult exposure to asbestos in steel workers revealed by bronchoalveolar lavage.

To investigate the asbestos burden in a steelplant environment, we counted asbestos bodies (ABs) in the bronchoalveolar lavage fluid (BALF) of 65 steel workers who had retired during the previous 5 y. They had worked for at least 15 y in the same area of the plant (coke oven or blast furnace) as maintenance or production workers. On the basis of occupational anamnesis, 28 had occasional past professional exposure to asbestos; the remaining 37 workers denied any contact with asbestos. A total of 54 white-collar workers who had no occupational exposure to asbestos were included in the study as controls. An increased prevalence and concentration of ABs was found in the BALF of steel workers. Electron microscopy and EDAX analysis of AB from steel workers revealed that the core fibers were mainly amphiboles. More ABs were found in the BALF of maintenance workers than in production workers. However, the BALF from steel workers who denied any contact with asbestos revealed an increased AB burden v. controls. This demonstrates that steel workers may be subject to an occult exposure to amphiboles in the steelplant environment.

Asbestos↗
PubMedDate not supplied

Age and smoking-adjusted lung cancer incidence in a Utah county with a steel mill.

In a recent study of urban air pollution, a Utah county with a steel mill was compared with a county without a steel mill. The result was that 38% of respiratory cancer deaths could be attributed to the air pollution emanating from the mill. Rates for smoking in this previous study were not adjusted, but assumed rats were similar in both counties. We used smoking information obtained from an ongoing radon and lung cancer case-control study to adjust for smoking, and no difference was found in incidence rates of respiratory cancer in the county with the steel mill, compared with the other urban counties and the rural counties among male and female nonsmokers and male smokers. There was a slight excess of lung cancer among female smokers in the county with the steel mill when compared with the other urban counties (rate ratio [RR] = 1.3, 95% confidence interval [95% CI] = 1.0-1.6), but there was no effect in nonsmoking women. We conclude that the findings of the previous study can be explained by differences in smoking rates between the county with the steel mill and the other counties.

Adult↗
PubMedDate not supplied

Adhesion of monocytes to medical steel as used for vascular stents is mediated by the integrin receptor Mac-1 (CD11b/CD18; alphaM beta2) and can be inhibited by semiconductor coating.

Implantation of stents into stenosed arteries helps to restore normal blood flow in ischemic organs. However, limited biocompatibility of the applied medical steel can cause acute thrombosis and long-term restenosis. Adhesion of monocytes to stent metal may participate in those acute and long-term complications of stent placement. Based on described prominent electrochemical properties of the interaction between the monocyte integrin receptor Mac-1 and its various ligands, we hypothesized, that this receptor is a central mediator of monocyte adhesion to stent metal and that semiconductor coating of medical steel reduces monocyte adhesion. Adhesion of monocytes on L-316 stainless steel was directly evaluated by light microscopy. Mac-1 could be identified as mediator of monocyte adhesion, since cell adhesion could be blocked by anti-Mac-1-antibodies, including the cross-reacting anti-GPIIb/IIIa antibody fragment abciximab. To further prove the central role of Mac-1, two CHO cell lines were generated expressing recombinant Mac-1 either as wild type, resulting in a low affinity receptor, or mutant with a GFFKR deletion of the alpha(M) subunit, resulting in a high affinity receptor. Indeed, adhesion was specific for Mac-1 and dependent on the affinity state of this integrin. Finally, we could demonstrate that Mac-1-mediated adhesion of monocytes to stents can be significantly inhibited by silicon carbide coating of the stent metal. In conclusion, the integrin Mac-1 and its affinity state could be identified as major mediators of monocyte adhesion on medical steel. As therapeutic strategies, the blockade of Mac-1 by antibodies or silicon carbide coating of steel inhibits monocyte adhesion on stents.

Adhesiveness↗
PubMed2004

Infectivity of prion protein bound to stainless steel wires: a model for testing decontamination procedures for transmissible spongiform encephalopathies.

OBJECTIVES: To establish an animal model to study transmissible spongiform encephalopathy using hamsters and steel wires contaminated with infectious brain materials as transfer vehicles, and, based on this model, to test decontamination procedures against the infectious prion proteins on the steel wires as a near real situation bioassay. DESIGN: Infectious brain materials were given to healthy hamsters intracerebrally either as a suspension or as dried materials on the surface of steel wires. The animals were observed for 18 months. During this period, animals showing definitive clinical signs were euthanized. Decontamination studies were performed by reprocessing contaminated steel wires with different disinfection agents and procedures before implantation. RESULTS: Pathological prion proteins were able to bind to the steel wires and caused disease after the contaminated wires were implanted in the brains of hamsters. When the contaminated wires were treated with different reprocessing procedures before implantation, infectivity was reduced, which was manifested directly by prolonged survival time of the test animals. These results show that this model can be used as a bioassay to validate reprocessing procedures for surgical instruments. CONCLUSIONS: At the time of submission of this article, only the group of hamsters incubated with wires reprocessed with an alkaline detergent, followed by sterilization with a modified cycle in a hydrogen peroxide gas plasma sterilizer (4 injections), showed no clinical signs of disease and remained alive. Two animals from the group receiving sodium hydroxide followed by autoclaving (at 134 degrees C for 18 minutes) died. Furthermore, the tested enzymatic cleaning agent seemed to have no positive effect.

Animals↗
PubMed2000

Influence of ceramic and stainless steel brackets on the notching of archwires during clinical treatment.

The surface topography of 100 clinically used archwires of stainless steel, beta-, or nickel-titanium were investigated that had contacted either ceramic or stainless steel brackets. One group consisted of two sets: 60 wires with no treatment records accessed to bias analyses, and 40 wires for which extensive clinical records were available, half of which were used with ceramic or stainless steel brackets. A control group consisted of two sets: 30 unused wires comprised of five round and rectangular wires of each alloy, and four wires that were ligated and immediately removed from patients' mouths. After ultrasonic cleaning, each wire was inspected under an optical and/or a scanning electron microscope. Notches were categorized with regard to frequency, patterns, and severity, and mapped as a function of wire aspect (lingual, facial, and occlusal/gingival) and anatomical regions (molar, premolar, canine, and incisor). From these data the average severity of notch patterns and a notching index were derived. Although no recognizable defect patterns were observed in the control group, seven basic patterns were recognized for each wire cross-sectional shape in the clinically used wires. These wires appeared most damaged on their lingual aspect and least damaged on their facial aspect. With regard to anatomical regions, notching was prevalent in the anterior regions and sparse in the molar regions. The notch activity and the severity were nearly three times greater from ceramic brackets than from stainless steel brackets. Over one-third of all notches documented in ceramic bracket cases had severity numbers of 3 and penetrated at least one-quarter of each wire's dimension, However, over two-thirds of all notches documented in stainless steel bracket cases had severity numbers of 1. From these tabulations a theory of notch formation was proposed in which vertical movement from tooth or wire during mastication caused fretting wear, and horizontal movement during orthodontic procedures such as space closure, tipping, or bodily movement caused sliding wear.

Ceramics↗
PubMedDate not supplied

Biomechanical comparison of stainless steel and titanium nails for fixation of simulated femoral fractures.

Flexible intramedullary nails are commonly used to treat femoral fractures in children. This study evaluated the biomechanical differences between stainless steel and titanium nails when securing transverse and comminuted fractures in a synthetic femur model. Retrograde flexible stainless steel and titanium nails placed in a divergent "C" pattern were mechanically tested, and axial rotation and compression stiffness were analyzed with a two-way ANOVA. Rotational stability was significantly greater for titanium nails than stainless steel nails for both fracture patterns. Axial compression stiffness was significantly greater for titanium nails than stainless steel nails for both fracture patterns. There was no statistical difference between materials for axial "failure" load that produced 5 mm of shortening. Titanium intramedullary nails were more stable than stainless steel nails in torsion and axial compression. Both materials stabilized simulated fractures at levels beyond physiologic non-weight-bearing loads without permanent deformation.

Biomechanical Phenomena↗
PubMed2004

Microstructural and microtextural characterization of oxide scale on steel using electron backscatter diffraction.

High-temperature oxidation of steel has been extensively studied. The microstructure of iron oxides is, however, not well understood because of the difficulty in imaging it using conventional methods, such as optical or electron microscopy. A knowledge of the oxide microstructure and texture is critical in understanding how the oxide film behaves during high-temperature deformation of steels and more importantly how it can be removed following processing. Recently, electron back-scatter diffraction (EBSD) has proved to be a powerful technique for distinguishing the different phases in scales. This technique gives valuable information both on the microstructure and on the orientation relationships between the steel and the scale layers. In the current study EBSD has been used to investigate the microstructure and microtexture of iron oxide layers grown on interstitial free steel at different times and temperatures. Heat treatments have been carried out under normal oxidation conditions in order to relate the results to real steel manufacturing in industry. The composition, morphologies, microstructure and microtexture of selected conditions have been studied using EBSD.

Ferric Compounds↗
PubMed2005

Canal preparation with Hero 642 rotary Ni-Ti instruments compared with stainless steel hand K-file assessed using computed tomography.

AIM: To compare ex vivo root canal preparation with conventional stainless steel K-files and Hero 642 rotary Ni-Ti instruments. METHODOLOGY: Mesiobuccal canals of 20 maxillary first molars (with angles of curvature between 25 degrees and 35 degrees ) were used. After preparation with Hero 642 rotary instruments and stainless steel K-files, the amount of transportation that occurred was assessed using computed tomography. The teeth were scanned by computed tomography before instrumentation. One millimetre thick slices were prepared from the apical end point to the pulp chamber. The first two sections were 3 mm from the apical end of the root (apical level) and 3 mm below the orifice (coronal level). A further section (mid-root level) was recorded, dividing the distance between the sections of apical and coronal levels into two equal lengths. Ten teeth were instrumented using Hero 642 rotary instruments and another 10 teeth were instrumented using stainless steel K-files. Following the completion of the instrumentation, the teeth were again scanned and compared with the cross-sectional images taken prior to canal preparation. Amount of transportation and centreing ability was assessed. Student's t-test was used for statistical analysis. RESULTS: Less transportation occurred with Hero 642 rotary instruments than stainless steel K-files at the mid-root and coronal levels (mid-root: P < 0.05 and coronal: P < 0.001). Hero 642 rotary instruments had better centreing ability than K-files at all three levels (apical: P < 0.05, mid-root: P < 0.05 and coronal: P < 0.001). CONCLUSIONS: Hero 642 rotary instruments transported canals less, especially at the middle and coronal thirds of the root canals than stainless steel K-files. Hero 642 instruments had better centreing ability.

Dental Alloys↗