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At least 127 records · Page 7Linked to original sources
PubMed2006

Cleanability of stainless steel surfaces as influenced by heat treatment.

The cleanability of heat-treated 316L stainless steel particles treated at various temperatures of 100 to 500 degrees C was studied in a plug-flow column fed by a 0.1M NaOH solution. Bovine Serum albumin (BSA) was used as the model fouling agent. Heat treatment resulted in the enrichment of iron in passive films on stainless steel particles depending on temperature. The degree of surface hydroxylation and the apparent surface charge density (sigma(app)) of stainless steel particles decreased markedly with increasing heating temperatures. The saturation amounts of BSA adsorbed (gamma(sat)) were larger on the particles heated at higher temperatures. No correlation was observed between the gamma(sat) and sigma(app) values. With increasing heating temperatures, the rate of BSA desorption from stainless steel particles decreased gradually in the initial and later stages of cleaning, resulting in larger amounts of BSA remaining on the particles at the end of 120-min of cleaning. The susceptibility to BSA adsorption and the cleanability were found to be correlated with the iron content of the passive films on stainless steel particles. It could be suggested that the decrease in the cleanability was probably due to the formation of iron-enriched passive films with lower degrees of surface hydroxylation of stainless steel particles due to heat treatment.

Adsorption↗
PubMed2006

Evaluation of chlorine, chlorine dioxide, and a peroxyacetic acid-based sanitizer for effectiveness in killing Bacillus cereus and Bacillus thuringiensis spores in suspensions, on the surface of stainless steel, and on apples.

Chlorine (10 to 200 microg/ml), chlorine dioxide (10 to 200 microg/ml), and a peroxyacetic acid-based sanitizer (40 and 80 microg/ ml) were evaluated for effectiveness in killing spores of Bacillus cereus and Bacillus thuringiensis in suspensions and on the surface of stainless steel and apples. Water and 5% horse serum were used as carriers for spore inoculum applied to the surface of stainless steel coupons, and 5% horse serum was used as a carrier for inoculum applied to apples. Inocula were dried on stainless steel for 5 h and on apples for 22 to 24 h before treating with sanitizers. At the concentrations of sanitizers tested, sensitivities of planktonic B. cereus and B. thuringiensis spores were similar. A portion of the spores surviving treatment with chlorine and, more markedly, chlorine dioxide had decreased tolerance to heat. Planktonic spores of both species were more sensitive to sanitizers than were spores on the surface of stainless steel or apples. At the same concentrations, chlorine was more effective than chlorine dioxide in killing spores in suspension and on stainless steel. The lethality of chlorine dioxide was markedly reduced when inoculum on stainless steel coupons was suspended in 5% horse serum as a carrier rather than water. Chlorine and chlorine dioxide at concentrations of 10 to 100 microg/ml were equally effective in killing spores on apples. Significant reductions of > or = 3.8 to 4.5 log CFU per apple were achieved by treatment with 100 microg/ml of either of the two sanitizers. The peroxyacetic acid sanitizer (40 and 80 microg/ml) was ineffective in killing Bacillus spores in the test systems investigated. Results provide information on the effectiveness of sanitizers commonly used in the food processing industry in killing Bacillus spores in suspension, on a food-contact surface, and on a ready-to-eat food.

Bacillus cereus↗
PubMed1975

[Titanium, steel and their combination in bone surgery].

The combined application of Titanium plates with stainless steel screws appeared interesting, making a more elastic plate available without the risk of screw fractures. 3 different combinations of Titanium und stainless steel implants were tested in the animal and on humans. A morphometric evaluation of the soft tissue (animal) gave similar good results for stainless steel implants as for the combination of Titanium and steel, while pure Titanium gave the best result. Atomic absorption tests (human) showed that in case of the Titanium/steel mixture only the stainless steel screws did corrode. Delayed fracture healing or mechanical instability always gave risk to more metal deposits in the soft tissue than primary bone healing. If the advantages of Titanium seem important and if the rigidity of stainless steel screws may not be missed, the combination of the two metals appears possible and without danger.

Alloys↗
PubMedDate not supplied

Colorimetric values of esthetic stainless steel crowns.

OBJECTIVES: The colorimetric values of two different kinds of esthetic stainless steel crowns were measured and compared with the colorimetric values of primary anterior teeth in Japanese children. METHOD AND MATERIALS: The colorimetric values of resin composite-faced stainless steel crowns (Kinder Krown) and epoxy-coated stainless steel crowns (White Steel Crown) were measured with a color difference meter. The Commission Internationale de Eclairage L*, a*, b*, and delta E*ab values and Munsell value, chroma, and hue were calculated. The data were compared with previously reported colorimetric values of Japanese primary anterior teeth measured with the same color difference meter used in this study. RESULTS: Compared to Japanese primary anterior teeth, Kinder Krown Pedo I and Pedo II showed much higher L* values and lower hue; on the other hand, White Steel Crown showed much higher L*, a*, b* values, much higher value and chroma, and much lower hue. CONCLUSION: Color analysis revealed that the colors of the White Steel Crown and Kinder Krown Pedo I were substantially different from the color of Japanese primary anterior teeth. The color difference between Pedo II crowns and Japanese primary anterior teeth was relatively high, but the color of Pedo II might be acceptable for clinical use.

Algorithms↗
PubMed2003

In vitro surface corrosion of stainless steel and NiTi orthodontic appliances.

Simulated fixed orthodontic appliances were constructed, immersed and incubated in artificial saliva for periods up to three months. Two types of stainless steel archwires and two types of NiTi wires were used. The surface corrosion of the archwires was determined macroscopically, with scanning electron microscopy, and with spectrophotometry. The deposits on the wires were identified with X-ray diffraction. Uniform corrosion was observed on stainless steel wires, and a slight colour change was detected on the NiTi wires beneath stainless steel ligatures. The corrosion product on the stainless steel wires increased with immersion time, and the surface oxide films were easily detached from the underlying matrix. Crevice corrosion was observed under deposits of oxide, and at the interface between bracket and band. Such corrosion may weaken a wire or weld leading to fracture. In contrast, the NiTi archwires did not corrode, and there was no significant difference in surface morphology. The stainless steel archwires showed a significant loss of reflectance after heat treatment and immersion in artificial saliva. The NiTi archwires had the same reflectance before and after the immersion test. NiTi archwires are significantly more stable and resistant to corrosion than stainless steel archwires.

Color↗
PubMed1976

Tissue reaction to middle ear prostheses: in vivo observation (rabbit ear lobe) of polyethylene tube, stainless steel wire and absorbable gelatin sponge used in middle ear surgery.

Over the past ten years, polyethylene tube, stainless steel wire and absorbable gelatin sponge have come to be used in middle ear surgery. A modified Williams' steel chamber with a transparent central area was embedded in a rabbit ear lobe surgically, and cross-sectioned polyethylene tube, stainless steel wire or absorbable gelatin sponge were inserted respectively. The in vivo tissue reaction to each of these installed materials was observed daily microscopically. Finally, in the case of both the cross-sectioned polyethylene tube and the stainless steel wire, the chambers were fixed with 10% formalin solution and the contents stained for histological study. The results were as follows: Absorbable gelatin sponge was absorbed completely by phagocytosis in 62 days. Polyethylene tube was encapsulated by a layer of fibroblasts by day 110 in one case and by day 140 in another case; these findings were confirmed histologically on day 110 and 281. Almost all the surface of the stainless steel wire was encapsulated by a layer consisting of giant cells, on which a dense fibrous layer was superimposed by day 82. It is concluded that polyethylene tube, stainless steel wire, and absorbable gelatin sponge should be well tolerated in middle ear surgery.

Absorption↗
PubMed1991

Corrosion potential of steel bird shot in dogs.

Each year many dogs are accidentally or purposely wounded with shotguns. When lead pellets were used exclusively in the past, clinical problems from chronically embedded shot seldom developed except for rare cases of lead toxicosis. However, because expended lead shot ingested unintentionally by waterfowl and other avian species is fatal, the US Fish and Wildlife Service mandated exclusive use of steel shot for waterfowl hunting beginning in 1991. To discover the effects of implanted steel shot in a biological system, in vitro and in vivo studies were performed. Severe surface corrosion was evident when steel shot was placed in physiologic saline solution and sterile canine plasma. Eight laboratory dogs were surgically implanted with sterile steel shot in various superficial locations for intervals of 2 to 26 weeks. Corrosion of implants and tissue inflammation was observed in all biopsy specimens examined. It has been shown that steel shot embedded in tissues will corrode and result in a severe inflammatory response. If the accompanying inflammation is complicated by bacterial contamination, foreign body reactions resulting in infected, draining tracts could develop. Veterinarians and dog owners should be aware that treatment and prognosis for wounds caused by steel shot may differ from those for similar wounds caused by lead shot.

Animals↗
PubMedDate not supplied

A study of plaque accumulation and gingival health surrounding stainless steel crowns.

From the findings of the present study the following can be stated: The degree of gingivitis surrounding teeth restored with nonideal stainless steel crowns was significantly higher than that of the entire mouth; however, the gingival status of the crowned teeth was not significantly different from that of unrestored contralateral control teeth. The amount of clinically detectable plaque associated with teeth restored with nonideal stainless steel crowns was not significantly different from that of the entire mouth or that of unrestored contralateral control teeth. A moderate positive correlation existed between the plaque index and the gingival index of teeth restored with nonideal stainless steel crowns; strong positive correlations between the same factors existed for the entire mouth and for the unrestored contralateral control teeth. The majority of stainless steel crowns placed by undergraduate dental students were judged as clinically acceptable. Nevertheless, most exhibited one or more observable defects: errors in marginal crimp and length were most common. In view of the association between nonideal stainless steel crowns and gingivitis, the operator must be meticulous in the placement of stainless steel crowns. Errors in adaptation must be avoided in order to minimize irritating factors and to preserve the health of the gingival tissues.

Child↗
PubMed1981

[Study of the distribution of chrome in 17 Cr stainless steel by autoradiography using 51Cr (author's transl)].

The segregation of alloying elements in steels even as small as undetectable in X-ray microanalysers seems to affect physical properties for instance, the ridging phenomenon in a 17 Cr stainless steel sheet due to fine wrinkles of the surface by drawing, the mechanism of which is not yet clear. Study was made of a method for detecting small segregations by autoradiography using 51Cr for the 17 Cr stainless steel. In results. (1) in the steel containing a 0.025% carbon or no carbon content, a small variation in photographic density relating to the concentration of chromium was found. (2) In the case of the steel with a 0.05% carbon content, similar one to commercial steel, a clear photographic density variation was observed which was considered to be a cause of the ridging. (3) The autoradiography is suitable to investigation of the small segregation undetected by an X-ray microanalyser.

Autoradiography↗
PubMedDate not supplied

Mechanical characteristics of poly-L-lactic acid absorbable screws and stainless steel screws in basilar osteotomies of the first metatarsal.

The purpose of this study is to evaluate the structural characteristics of 3.5-mm. stainless steel cortical screws and poly-L-lactic acid (PLA) absorbable screws in oblique closing base wedge osteotomies of the first metatarsal. Six pairs of frozen first metatarsal bones were excised from the specimen group. An oblique base wedge osteotomy was performed and fixated with either a 3.5-mm. stainless steel or PLA screw. Specimens were loaded to failure with the Bionix Material Testing System at a constant rate of 0.166 mm./sec. A Student's t test for paired samples with a 95% confidence interval was used to measure differences in ultimate load, ultimate displacement, and structural stiffness. The following results (mean +/- standard deviation) were obtained: Structural stiffness, PLA 12.35 +/- 3.82 N/mm. and stainless steel 10.13 +/- 5.74 N/mm.: ultimate displacement, PLA 7.39 +/- 3.23 mm. and stainless steel 10.89 +/- 7.91 mm.; ultimate load, PLA 57.95 +/- 1.01 N and stainless steel 51.49 +/- 5.22 N. In this fracture model, there were no statistically significant differences in the structural characteristics of PLA 3.5-mm. screws and stainless steel screws in oblique closing base wedge osteotomies of the first metatarsal.

Absorption↗
PubMed1993

Dynamic changes in ovarian c-kit and Steel expression during the estrous reproductive cycle.

W and Steel mutant mice exhibit similar developmental defects in melanogenesis, haematopoiesis, and gametogenesis. Consistent with the cell autonomous and microenvironmental nature of W and Sl mutations, respectively, W encodes the c-kit receptor tyrosine kinase while Steel encodes the Kit ligand. Both c-kit and Steel are expressed in various cells in which no corresponding mutant phenotype has yet been demonstrated. In the adult ovary, certain stromal-derived cells (theca and interstitial), as well as oocytes, express c-kit, while granulosa cells express Steel. We show here that the cessation of oocyte growth, at the transition of the follicle to the antral stage, is associated with the cessation of Steel expression in the cumulus granulosa cells in the vicinity of the oocyte. These observations suggest a role for the Kit signaling pathway in oocyte growth or in meiotic arrest. In addition, the cyclic secretion of luteinizing hormone immediately and dramatically results in elevated Steel expression in mural granulosa cells and decreased levels of c-kit transcripts in stromal-derived cells. This influence of the estrous reproductive cycle on c-kit/Steel expression suggests that the Kit signaling pathway, in addition to its previously described role in primordial germ cell development, is involved in follicular development in the adult female.

Animals↗
PubMed2001

Production of Oil-in-Water Microspheres Using a Stainless Steel Microchannel.

From the point of view of practical application of the microchannel (MC) emulsification technique, which can be used to produce super-monodispersed microspheres (MS), we fabricated a stainless steel MC and investigated the production and characterization of oil-in-water (O/W) MS using a stainless steel MC instead of a silicon MC plate. We discovered that a stainless steel MC could not be fabricated precisely at a 1-&mgr;m scale; because of its multicrystal property, it can only be processed mechanically on a 10-&mgr;m scale. O/W-MS ranging from 20 to 210 &mgr;m in average diameter were produced using a stainless steel MC with 10 to 80 &mgr;m in equivalent diameter. The MS produced were monodispersed with a coefficient of variation lower than 3% for each individual channel. This value is smaller than that of normal emulsions obtained by the conventional emulsification techniques by 1 order of magnitude. The average diameter of the MS produced at breakthrough pressure was about 2.6 times the stainless steel MC equivalent diameter. The operation pressure affects the MS formation, causing a size-stable zone, size-expanding zone, and outflow zone observed. Larger stainless steel MC demonstrated difficulties in stably producing monodispersed O/W-MS. The breakthrough pressure was approximately inversely proportional to the MC equivalent diameter. Copyright 2001 Academic Press.

Journal Article↗
PubMed1990

Transgene-induced mutation of the murine steel locus.

The product of the steel locus is essential for normal development of three distinct populations of stem cells--the neural crest-derived melanoblasts, germ cells, and blood cell precursors. Many mutant alleles at steel are lethal in homozygotes and produce coat color dilution in heterozygotes. We have identified a transgenic mouse with diluted pigmentation that closely resembles that of steel heterozygotes. We have demonstrated that the site of transgene insertion is genetically linked to the phenylalanine hydroxylase locus on mouse chromosome 10. In addition, the chromosome carrying the transgene fails to complement the recessive lethality of the Sl allele of steel and the pigmentation defect of the Slpan allele. The data indicate that the inserted transgene has disrupted the steel locus. The resulting allele, designated Sltg, provides a molecular tag for isolation of the steel gene, as well as a new allele for characterization of this developmentally important locus.

Animals↗
PubMed2001

Radiocesium in fish from the Savannah River and Steel Creek: potential food chain exposure to the public.

This study examined radiocesium (137Cs) levels in fish from the vicinity of the Department of Energy's Savannah River Site (SRS), a former nuclear weapons production facility in South Carolina. Fish from the Savannah River were sampled above (upstream), along, and below (downstream) the SRS, and from Steel Creek, a tributary that runs through the SRS. There was some off-site contamination of 137Cs in the Savannah River watershed due to low-level releases from past nuclear production on the SRS. The null hypotheses tested were that there would be no differences in 137Cs levels as a function of location along the river, and between species collected from the river and from Steel Creek on the SRS. For six of eight species of fish collected from the Savannah River, there were no differences in 137Cs levels in muscle from fish collected above, along, or below the SRS; exceptions were bowfin and shellcracker. Fish collected from Steel Creek had significantly higher levels (by about an order of magnitude) of 137Cs in muscle tissue than fish collected in the Savannah River. However, no fish from either Steel Creek or the Savannah River had 137Cs levels above the European Economic Community limit for fresh meat of 0.6 Bq/g. Lifetime cancer risk was calculated using the cancer slope factor of 3.2 x 10(-11)/pCi, and various fish consumption scenarios reflecting actual data from Savannah River fishermen. Using mean 137Cs concentrations and median fish consumption for 70 years for Black males-the group with the highest consumption-the excess lifetime risk associated with the eight species of fish in the Savannah River ranged from 9.0 x 10(-7) to 1.0 x 10(-5). The same calculation for fish from Steel Creek gave risk estimates from 1.4 to 8.0 x 10(-5). The 95% level for consumption by Blacks, however, was about 70 kg/year. Black fishermen consuming that amount of bass from Steel Creek would sustain a lifetime risk of 3.1 x 10(-4), whereas the same consumption of Savannah River bass would yield a risk estimate of 1.5 x 10(-5).

Animals↗
PubMed2006

Hydrogen-induced defects in austenite and ferrite of a duplex steel.

The influence of hydrogen on the microstructure of two types of austeno-ferritic duplex stainless steel (Cr26-Ni6 model steel and Cr22-Ni5-Mo3 commercial steel), each of them after two thermo-mechanical treatments, was investigated. The aim of this study was to reveal microstructural changes appearing during the hydrogen charging and particularly to clarify the occurrence of phase transformations induced by hydrogen. The specific microstructural changes in the ferrite (alpha) and austenite (gamma) of both types of steel were observed. A strong increase of dislocation density was noticed in the alpha phase. In the case of model steel, longer hydrogen charging times led to significant ferrite grain refinement. In the commercial steel, the strips and twin plates appeared in the ferrite after hydrogenation. The appearance of stacking faults was revealed in the gamma phase. The martensite laths appeared in austenite after longer hydrogenation times. It seems that the microstructural changes gave rise to the formation of microcracks in the alpha and gamma phases as well as on the alpha/gamma interphase boundaries.

Journal Article↗
PubMed1991

Contiguous patterns of c-kit and steel expression: analysis of mutations at the W and Sl loci.

Mutations in either the dominant white-spotting (W) or Steel (Sl) loci of the mouse lead to coat color, primordial germ cell and hematopoietic defects. Consistent with the cell autonomous and microenvironmental nature of W and Sl mutations, respectively, it has recently been shown that W encodes the c-kit receptor tyrosine kinase while Sl encodes a ligand for this receptor. Previous in situ hybridization analysis has shown that both c-kit and steel are expressed in the embryo in anatomical sites known to be affected by W and Sl mutations and in various tissues in which no corresponding phenotype has been described. To investigate the possible involvement of the Kit transduction pathway in developmental processes, we compared the patterns of expression of c-kit and steel in wild-type embryos and in embryos homozygous for severe (lethal) and mild (viable) alleles at the W and Sl loci. In addition, we analyzed the patterns of expression of both genes in adult wild-type and mutant gonads and brain. Both c-kit and steel are contiguously expressed in a wide variety of anatomical locations in both the developing embryo and in the adult. In adult gonads, steel is expressed in the follicular cells of the ovary and in Sertoli cells of the testis, the layers that immediately surround the c-kit expressing germ cells. In adult brain, the complementary patterns are particularly striking in the olfactory bulb, cerebral cortex, hippocampus region and cerebellum. steel expression in brain is probably restricted to neurons in certain areas, while c-kit is expressed in neurons and in some glial cells. Severe mutations in the W or Sl loci result in dramatic reduction or absence of c-kit positive cells in lineages known to be affected by these mutations. In contrast, these mutations do not affect the number or histological organization of c-kit positive cells in the embryonic peripheral or central nervous systems, nor is the number or organization of c-kit positive cells detectably altered in Wv/Wv or Sld/Sld adult brain. Taken together, these results suggest that the Kit signaling pathway is not obligatory for the viability and/or migration of most c-kit expressing cells either because of functional redundancy with another signaling pathway or because the Kit pathway is involved in post-developmental processes of mature cells.

Animals↗
PubMed1995

Soluble and cell-bound forms of steel factor activity play distinct roles in melanocyte precursor dispersal and survival on the lateral neural crest migration pathway.

Trunk neural crest cells segregate from the neuroepithelium and enter a 'migration staging area' lateral to the embryonic neural tube. After some crest cells in the migration staging area have begun to migrate on a medial pathway, a subpopulation of crest-derived cells remaining in the migration staging area expresses mRNAs for the receptor tyrosine kinase, c-kit, and tyrosinase-related protein-2, both of which are characteristic of melanocyte precursors. These putative melanocyte precursors are subsequently observed on the lateral crest migration pathway between the dermatome and overlying epithelium, and then dispersed in nascent dermal mesenchyme. Melanocyte precursors transiently require the c-kit ligand, Steel factor for survival. Although Steel factor mRNA is transiently expressed in the dorsal dermatome before the onset of trunk neural crest cell dispersal on the lateral pathway, it is no longer produced by dermatomal cells when melanocyte precursors have dispersed in the dermal mesenchyme. To assess the role of Steel factor in migration of melanocyte precursors on the lateral pathway, we analyzed melanocyte precursor dispersal and fate on the lateral pathway of two different Sl mutants, Sl, a null allele, and Sld, which lacks cell surface-associated Steel factor but produces a soluble form. No melanocyte precursors were detected in the dermatome of embryos homozygous for the Sl allele or in W mutants that lack functional c-kit. In contrast, in embryos homozygous for the Sld allele, melanocyte precursors appeared on the lateral pathway, but subsequently disappear from the dermis. These results suggest that soluble Steel factor is required for melanocyte precursor dispersal on the lateral pathway, or for their initial survival in the migration staging area. In contrast, membrane-bound Steel factor appears to promote melanocyte precursor survival in the dermis.

Animals↗
PubMed1991

Diamond-Blackfan anemia: heterogenous response of hematopoietic progenitor cells in vitro to the protein product of the steel locus.

Diamond-Blackfan anemia is a congenital disorder of erythropoiesis in humans, characterized by a macrocytic anemia often associated with physical anomalies. Mutations at either the W or Steel loci in the mouse also leads to a severe macrocytic anemia, as well as other developmental abnormalities. The W locus encodes the proto-oncogene c-kit, a member of the receptor tyrosine kinase family, while the Steel locus encodes a potent hematopoietic growth factor that is the ligand for c-kit. Growth of clonogenic marrow erythroid progenitor cells in vitro in the presence of the recombinant hematopoietic growth factors interleukin-3 (IL-3) and Steel was used to characterize this disease at the cellular level. Three patterns of in vitro marrow response to both recombinant IL-3 or Steel were observed among 10 Diamond-Blackfan patients: those that responded quantitatively and qualitatively almost as well as cells from normal marrow, those that responded at an intermediate level, and those that did not respond at all. These results provide evidence for cellular heterogeneity underlying the pathogenesis of this disorder and therefore raise the possibility that there may be more than one underlying molecular basis for the disease. No gross abnormalities in the structure of either the c-kit or Steel loci were observed in these patients. The normal response in culture of the progenitor cells from at least some patients to Steel with or without IL-3 raises the possibility of using this novel growth factor as a therapeutic agent in Diamond-Blackfan anemia.

Adolescent↗