Note: This page contains sample records for the topic bracket base surface from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Surfaces and the Sklyanin Bracket  

Microsoft Academic Search

:  ?We discuss the Lie Poisson group structures associated to splittings of the loop group LGL(N,?), due to Sklyanin. Concentrating on the finite dimensional leaves of the associated Poisson structure, we show that the geometry\\u000a of the leaves is intimately related to a complex algebraic ruled surface with a ?\\u000a *-invariant Poisson structure. In particular, Sklyanin's Lie Poisson structure admits a

J. C. Hurtubise; E. Markman

2002-01-01

2

Orthodontic molar brackets: the effect of three different base designs on shear bond strength.  

PubMed

The purpose of the study was to assess the relative base designs of three different maxillary molar stainless steel brackets with reference to the shear bond strength of three different adhesive resins. The molar brackets used were Victory series (3M Unitek), Upper Molar (GAC) and Optimesh XRT (Ormco). The adhesives used were Transbond XT (3M Unitek), Enlight (Ormco) and Sure Ortho Light Bond (Sure Orthodontics). The human enamel specimens (144) were randomly divided into nine groups and each group (n=16) was allocated to a bracket/adhesive combination. The contact surface of each of the bracket bases was measured three dimensionally using a reflex microscope. The base designs were also subjected to further microscopic investigations. The brackets were bonded to the enamel, temperature cycled and the shear bond strength was measured. The size and design of each of the brackets was different. The base size, surface treatment, mesh strand diameter and aperture size of the bracket base mesh have a significant effect on the shear bond strength at the bracket/adhesive interface. The shear bond strengths of all three Ormco bracket/adhesive resin combinations (5.8-6.8 MPa) were significantly lower (p<0.05; Kruskal-Wallis) than the other six bracket/adhesive combinations (9.4-12.1 MPa). The different adhesive types (3 types) could not be mainly responsible for the low shear bond values found for the Ormco bracket. The 3M Unitek combination of the Victory series bracket and Transbond XT adhesive proved to have a high shear bond strength without enamel damage. PMID:23675217

Hudson, Athol P; Grobler, Sias R; Harris, Angela M P

2011-03-01

3

Orthodontic Molar Brackets: The Effect of Three Different Base Designs on Shear Bond Strength  

PubMed Central

The purpose of the study was to assess the relative base designs of three different maxillary molar stainless steel brackets with reference to the shear bond strength of three different adhesive resins. The molar brackets used were Victory series (3M Unitek), Upper Molar (GAC) and Optimesh XRT (Ormco). The adhesives used were Transbond XT (3M Unitek), Enlight (Ormco) and Sure Ortho Light Bond (Sure Orthodontics). The human enamel specimens (144) were randomly divided into nine groups and each group (n=16) was allocated to a bracket/adhesive combination. The contact surface of each of the bracket bases was measured three dimensionally using a reflex microscope. The base designs were also subjected to further microscopic investigations. The brackets were bonded to the enamel, temperature cycled and the shear bond strength was measured. The size and design of each of the brackets was different. The base size, surface treatment, mesh strand diameter and aperture size of the bracket base mesh have a significant effect on the shear bond strength at the bracket/adhesive interface. The shear bond strengths of all three Ormco bracket/adhesive resin combinations (5.8-6.8 MPa) were significantly lower (p<0.05; Kruskal-Wallis) than the other six bracket/adhesive combinations (9.4-12.1 MPa). The different adhesive types (3 types) could not be mainly responsible for the low shear bond values found for the Ormco bracket. The 3M Unitek combination of the Victory series bracket and Transbond XT adhesive proved to have a high shear bond strength without enamel damage.

Hudson, Athol P.; Grobler, Sias R.; Harris, Angela M. P.

2011-01-01

4

Effect of surface treatment of brackets and mechanical cycling on adhesion to enamel.  

PubMed

This in vitro study sought to evaluate how surface conditioning from bracket and mechanical cycling aging affected the bond strength between metallic brackets and bovine enamel, and to determine the adhesive remnant index. Eighty bovine incisors were embedded in acrylic resin using polyvinyl chloride rings and divided into 4 groups based on surface treatment (n = 20). Group 1 (control) received no surface treatment, Group 2 specimens were sandblasted with aluminum oxide particles, Group 3 specimens were sandblasted with silicon oxide and treated with a tribochemichemical silica coupling agent, and Group 4 specimens were primed with a multidomain protein-based agent. Half of the specimens were submitted to shear bond testing, while the others were subjected to mechanical cycling. ANOVA showed that mechanical cycling did not have a significant influence on bond strength (P = 0.9244), while surface conditioning of the brackets did (P = 0.0001). Tukey's test results were similar for mechanical cycling, and indicated that only Group 3 significantly improved the resin bond to the brackets; however, this group also demonstrated the highest percentage of enamel failure. PMID:24784526

Arrais, Fabiola Rossato; Degrazia, Felipe; Peres, Bernardo Urbanetto; Ferrazzo, Vilmar Antonio; Grehs, Renesio Armindo; Valandro, Luiz Felipe

2014-01-01

5

In vitro shearing force testing of the Australian zirconia-based ceramic Begg bracket.  

PubMed

The purpose of this study was to investigate the condition of bond failure of the Australian zirconia-based ceramic Begg bracket (Elipse bracket) in comparison with that of a small-base metal Begg bracket (Solitaire bracket) under various environmental conditions. Shear tests were performed and sites of bond failure were also recorded. The results showed that (1) mean shear force of the bonded Elipse ceramic bracket is significantly higher than the metal one (2) shearing force at failure in both ceramic and metal groups, is considered clinically acceptable, (3) thermocycling (1000 cycles) had no significant additional effect on shearing force with both groups, (4) failure sites of the bonding were more likely to be at enamel/resin interfaces, and (5) there was no instance of fracture of the ceramic bracket and the enamel. A particular distinction is noted concerning the test results that measured shearing force rather than shear strength. It is questioned whether some published reports referring to "shear strength" have adequately accounted for bond surface area estimation necessary for proper calculation of strength values. PMID:7661149

Kittipibul, P; Godfrey, K

1995-09-01

6

Changes in the surface roughness and friction coefficient of orthodontic bracket slots before and after treatment.  

PubMed

In this study, we tested the surface roughness of bracket slots and the friction coefficient between the bracket and the stainless steel archwire before and after orthodontic treatment. There were four experimental groups: groups 1 and 2 were 3M new and retrieved brackets, respectively, and groups 3 and 4 were BioQuick new and retrieved brackets, respectively. All retrieved brackets were taken from patients with the first premolar extraction and using sliding mechanics to close the extraction space. The surface roughness of specimens was evaluated using an optical interferometry profilometer, which is faster and nondestructive compared with a stylus profilometer, and provided a larger field, needing no sample preparation, compared with atomic force microscopy. Orthodontic treatment resulted in significant increases in surface roughness and coefficient of friction for both brands of brackets. However, there was no significant difference by brand for new or retrieved brackets. These retrieval analysis results highlight the necessity of reevaluating the properties and clinical behavior of brackets during treatment to make appropriate treatment decisions. PMID:23086715

Liu, Xiaomo; Lin, Jiuxiang; Ding, Peng

2013-01-01

7

The Influence of No-Primer Adhesives and Anchor Pylons Bracket Bases on Shear Bond Strength of Orthodontic Brackets  

PubMed Central

Objective. The aim of this study was to compare the shear bond strength (SBS) and adhesive remnant index (ARI) scores of no-primer adhesives tested with two different bracket bases. Materials and Methods. 120 bovine permanent mandibular incisors were divided into 6 groups of 20 specimens. Two brackets (ODP) with different bracket bases (anchor pylons and 80-gauge mesh) were bonded to the teeth using a conventional adhesive (Transbond XT) and two different no-primer adhesive (Ortho Cem; Heliosit) systems. Groups were tested using an instron universal testing machine. SBS values were recorded. ARI scores were measured. SEM microphotographs were taken to evaluate the pattern of bracket bases. Statistical analysis was performed. ANOVA and Tukey tests were carried out for SBS values, whereas a chi-squared test was applied for ARI scores. Results. Highest bond strength values were reported with Transbond XT (with both pad designs), Ortho Cem bonded on anchor pylons and Heliosit on 80-gauge mesh. A higher frequency of ARI score of “3” was reported for Transbond XT groups. Other groups showed a higher frequency of ARI score “2” and “1.” Conclusion. Transbond XT showed the highest shear bond strength values with both pad designs.

Sfondrini, Maria Francesca; Fraticelli, Danilo; Daina, Paola; Tamagnone, Alessandra; Gandini, Paola

2013-01-01

8

Effect of a DPSS laser on the shear bond strength of ceramic brackets with different base designs.  

PubMed

This study evaluated the shear bond strength (SBS) and adhesive remnant index (ARI) of ceramic brackets with different base designs using a 473-nm diode-pumped solid-state (DPSS) laser to test its usefulness as a light source. A total of 180 caries-free human premolars were divided into four groups according to the base designs: microcrystalline, crystalline particle (CP), dovetail, and mesh. For each base design, teeth were divided into three different subgroups for light curing using three different light-curing units (LCUs) (quartz-tungsten-halogen unit, light-emitting diode unit, and a DPSS laser of 473 nm). Applied light intensities for the DPSS laser and the other LCUs were approximately 630 and 900 mW/cm(2), respectively. Stainless steel brackets with a mesh design served as controls. The failure modes of debonded brackets were scored using ARI. As a result, brackets bonded using the DPSS laser had the highest SBS values (16.5-27.3 MPa) among the LCUs regardless of base design. Regarding base designs, the CP groups showed the highest SBS values (22.9-27.3 MPa) regardless of LCU. Furthermore, stainless steel brackets with a mesh design had the lowest SBS values regardless of LCU. In many cases, brackets bonded using the DPSS laser had higher ARI scores and had more adhesive on their bases than on tooth surfaces. The study shows that the 473-nm DPSS laser has considerable potential for bonding ceramic brackets at lower light intensities than the other light-curing units examined. PMID:23135786

Park, Mi-Gyoung; Ro, Jung-Hoon; Park, Jeong-Kil; Ko, Ching-Chang; Kwon, Yong Hoon

2013-11-01

9

Variations in surface characteristics and corrosion behaviour of metal brackets and wires in different electrolyte solutions.  

PubMed

The aim of this study was to assess the surface characteristics and to compare the corrosion potential of metal brackets and wires in environments containing different media. Four brands of metal brackets and two types of orthodontic wires [stainless steel and nickel-titanium (NiTi)] were investigated. An electrochemical assay was used to compare the corrosion potential (V) of the brackets and wires in different electrolyte media at 37°C. The test media were acidulated sodium fluoride (NaF) and pH 4 and pH 6 artificial saliva solutions. The data were analysed using analysis of variance with a predetermined significance level of ? = 0.05. Scanning electron microscopy (SEM) was used to observe surface defects and corrosion. The results of the potentiodynamic curve showed that most brands of metal brackets were easily corroded in the NaF and pH 4 environments, while the NiTi and stainless steel wires were easily corroded in the pH 4 artificial saliva. SEM observations showed that defects or pitting corrosion occurred on the surfaces of the brackets and wires in all tested media. PMID:20139132

Kao, Chia-Tze; Huang, Tsui-Hsien

2010-10-01

10

Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets  

Microsoft Academic Search

The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-m) or rough (125-m) diamond bur, sandblasting (50-m or 110-m aluminum oxide (Al2O3)), and silica coating (30-m silica). Fifty disc-shaped specimens of 5 different alloys (gold-silver, palladium-silver, nickel-chromium, cobalt- chromium, and titanium) were ground with

Ibrahim Nergiz; Mutlu Ozcan

11

Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets  

Microsoft Academic Search

The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-?m) or rough (125-?m) diamond bur, sandblasting (50-?m or 110-?m aluminum oxide [Al2O3]), and silica coating (30-?m silica). Fifty disc-shaped specimens of 5 different alloys (gold-silver, palladium-silver, nickel-chromium, cobalt-chromium, and titanium) were ground with 1200-grit

Ibrahim Nergiz; Petra Schmage; Wolfram Herrmann; Mutlu Özcan

2004-01-01

12

Effects of silanation time on shear bond strength between a gold alloy surface and metal bracket  

PubMed Central

Objective We aimed to investigate the effects of silanation time on the shear bond strength (SBS) of metal brackets on gold alloy in a silicoating procedure and compare the SBS of metal brackets on gold alloy and enamel. Methods Type III gold alloy plates were sandblasted with 30-µm silicon dioxide. Excess particles were removed with gentle air after silica coating, and silane was applied. Maxillary central-incisor metal brackets were bonded to each conditioned alloy surface with a light curing resin adhesive for 1 s, 30 s, 60 s, or 120 s after applying silane. The brackets were also bonded to 36 upper central incisors with the same adhesive. All samples were cured for 40 s with a light emitting diode curing light. The SBS was tested after 1 h and after 24 h. The adhesive remnant index (ARI) of the samples was also compared. Results The 60-s and 120-s silanation time groups showed a higher SBS than the other groups (p < 0.05). Samples tested after 24 h showed a significantly higher SBS than did the samples tested after 1 h (p < 0.05). The 1-s group showed higher ARI scores. The one-way analysis of variance and Student-Newman-Keuls test showed that the SBS values of the 60-s and 120-s silanation time groups were not significantly different from the SBS values of enamel. Conclusions Adequate silanation time is required to produce sufficient bond strength during silicoating.

Shon, Won-Jun; Park, Young-Seok; Chung, Shin-Hye

2013-01-01

13

Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces  

Microsoft Academic Search

With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface conditioning methods: fine diamond bur, sandblasting, 5% hydrofluoric acid, and silica coating

Petra Schmage; Ibrahim Nergiz; Wolfram Herrmann; Mutlu Özcan

2003-01-01

14

Debonding forces of three different customized bases of a lingual bracket system  

PubMed Central

Objective The purpose of this study was to investigate whether extension of the custom base is necessary for enhancement of bond strength, by comparing the debonding forces and residual adhesives of 3 different lingual bracket systems. Methods A total of 42 extracted upper premolars were randomly divided into 3 groups of 14 each for bonding with brackets having (1) a conventional limited resin custom base; (2) an extended gold alloy custom base: Incognito™; and (3) an extended resin custom base: KommonBase™. The bonding area was measured by scanning the bracket bases with a 3-dimensional digital scanner. The debonding force was measured with an Instron universal testing machine, which applied an occlusogingival shear force. Results The mean debonding forces were 60.83 N (standard deviation [SD] 10.12), 69.29 N (SD 9.59), and 104.35 N (SD17.84) for the limited resin custom base, extended gold alloy custom base, and extended resin custom base, respectively. The debonding force observed with the extended resin custom base was significantly different from that observed with the other bases. In addition, the adhesive remnant index was significantly higher with the extended gold alloy custom base. Conclusions All 3 custom-base lingual brackets can withstand occlusal and orthodontic forces. We conclude that effective bonding of lingual brackets can be obtained without extension of the custom base.

Sung, Jang-Won; Kwon, Tae-Yub

2013-01-01

15

Shear bond strength of orthodontic brackets bonded to different ceramic surfaces.  

PubMed

This study was undertaken to measure the shear bond strength (SBS) of stainless steel brackets bonded to different ceramic surfaces, to compare the SBS of the different ceramics with each other and with conventional ceramo-metal porcelains, and to determine the mode of failure for each group following debonding. A total of 60 ceramic crowns were constructed on extracted teeth and divided into three equal groups as follows: In-Ceram ceramic crowns, IPS-Impress ceramic crowns, and conventional ceramo-metal porcelain. Standard edgewise metal premolar brackets were bonded to the prepared porcelain surfaces. After bonding, all samples were tested in shear mode on an Instron universal testing machine. Statistical analysis was undertaken using analysis of variance, LSD, and chi-squared tests. The results showed that the SBS for the ceramo-metal and the In-Ceram groups were comparable, with mean values of 80.54 +/- 13.44 N and 78.87 +/- 13.47 N, respectively. The IPS-Impress group showed the weakest SBS which averaged 67.40 +/- 8.99 N. This was significantly lower than that of the conventional ceramo-metal porcelain (P < 0.001) and the In-Ceram surface (P < 0.01). The mode of failure in the ceramo-metal group was between the porcelain surface and adhesive and in the other two ceramic groups, between the brackets and adhesive (P < 0.001). The SBS of orthodontic brackets to the three tested ceramic surfaces were adequate for orthodontic use. PMID:17702799

Abu Alhaija, Elham S J; Al-Wahadni, Ahed M S

2007-08-01

16

The effect of different surface treatments of demineralised enamel on microleakage under metal orthodontic brackets  

PubMed Central

Background The aim of this investigation was to assess the effects of different treatments of demineralised enamel on microleakage under orthodontic brackets. Methods Seventy-five intact premolars were randomly assigned to five groups. The teeth in groups 2 through 5 were immersed in a demineralising solution for 16 weeks. In groups 1 (control) and 2 (demineralised/control), conventional acid etching was used. In group 3, sodium hypochlorite (NaOCl) was applied on the enamel surface for 1 min after acid etching, and in group 4, Transbond Plus (3M Unitek, Monrovia, CA, USA) self-etching primer (SEP) was used. The teeth in group 5 were treated with 2% sodium fluoride (NaF) for 4 min before etching. After bracket bonding, the specimens were thermocycled, sealed with nail varnish, immersed in 0.5% basic fuchsine solution for 24 h and sectioned. Microleakage was measured under a stereomicroscope for the enamel-adhesive and adhesive-bracket interfaces of both occlusal and gingival sides. Results Demineralised teeth showed more microleakage at the enamel-adhesive interface on both occlusal and gingival sides compared to sound teeth, but the difference was not significant (P > 0.005). Treating the demineralised enamel with 5% NaOCl or Transbond Plus SEP was not effective in reducing microleakage. NaF treatment followed by acid etching of demineralised enamel resulted in significantly lower microleakage in most comparisons (P < 0.005). Conclusions The use of 2% NaF on hypomineralised enamel before the bracket bonding procedure is an effective way to decrease microleakage.

2013-01-01

17

A comparative study of shear bond strength between metal and ceramic brackets and artificially aged composite restorations using different surface treatments.  

PubMed

This in vitro study evaluated the shear bond strength (SBS) between ceramic brackets (CBs) and resin composite restorations (RCRs) prepared using different surface treatments. The findings were also compared with a similar study that used stainless steel brackets (SSBs). Forty-five premolars were restored with a nano-hybrid composite resin (Tetric EvoCeram) and randomly assigned to three surface treatment groups: group 1, 5 per cent hydrofluoric acid (HF); group 2, air abrasion (50 ?m alumina particles); and group 3, diamond bur. Specimens were bonded with CBs (Fascination) and exposed to thermo-cycling (500 cycles). The shear force at a crosshead speed of 1 mm/minute was transmitted to brackets. The adhesive remnant index (ARIs) scores were recorded after bracket failure. The analysis of SBS variance (P < 0.01) and chi-square test of ARIs scores (P < 0.01) revealed significant differences among three groups tested. The SBS in group 3 (mean: 26.34 ± 4.76 MPa) and group 2 (mean: 26.68 ± 5.93 MPa) was significantly higher than group 1 (mean: 16.25 ± 5.42 MPa). The SBS was significantly higher in CBs (mean: 23.09 ± 7.19 MPa) compared to SSBs (mean: 15.56 ± 5.13 MPa). High ARIs (100 per cent) occurred in SSBs treated with a diamond bur, whereas CBs primarily failed at the resin-adhesive interface (P < 0.01). In two-thirds of the specimens (SSBs or CBs), no adhesive was left on the restoration after HF conditioning. The ARIs profile of CBs and SSBs that received surface treatments with air abrasion were similar (P > 0.05) and bond failure occurred mainly in adhesive-bracket base and resin-adhesive interfaces. The diamond bur surface treatment is recommended as a safe and cost-effective method of bonding CBs to RCRs. PMID:21447779

Eslamian, Ladan; Borzabadi-Farahani, Ali; Mousavi, Nasim; Ghasemi, Amir

2012-10-01

18

Enamel Surface Roughness after Debonding of Orthodontic Brackets and Various Clean-Up Techniques  

PubMed Central

Objective: This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. Materials and Methods: The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively), an ultrafine diamond bur (group 3) or an Er:YAG laser (250 mJ, long pulse, 4 Hz) (group 4), and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed. Results: The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05). Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01). In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05). Conclusion: Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets.

Ahrari, Farzaneh; Akbari, Majid; Akbari, Javad; Dabiri, Ghahraman

2013-01-01

19

Effect of chlorhexidine-containing prophylactic agent on the surface characterization and frictional resistance between orthodontic brackets and archwires: an in vitro study  

PubMed Central

Background The purpose of this study was to assess the surface characterization and frictional resistance between stainless steel brackets and two types of orthodontic wires made of stainless steel and nickel-titanium alloys after immersion in a chlorhexidine-containing prophylactic agent. Methods Stainless steel orthodontic brackets with either stainless steel (SS) or heat-activated nickel-titanium (Ni-Ti) wires were immersed in a 0.2% chlorhexidine and an artificial saliva environment for 1.5 h. The frictional force was measured on a universal testing machine with a crosshead speed of 10 mm/min over a 5-mm of archwire. The surface morphology of bracket slots and surface roughness of archwires after immersion in chlorhexidine were also characterized using a scanning electron microscope (SEM) and an atomic force microscope (AFM), respectively. Results There was no significant difference in the frictional resistance values between SS and Ni-Ti wires immersed in either chlorhexidine or artificial saliva. The frictional resistance values for the SS and Ni-Ti wires immersed in 0.2% chlorhexidine solution were not significantly different from that inartificial saliva. No significant difference in the average surface roughness for both wires before (as-received) and after immersion in either chlorhexidine or artificial saliva was observed. Conclusions One-and-half-hour immersion in 0.2% chlorhexidine mouthrinse did not have significant influence on the archwires surface roughness or the frictional resistance between stainless steel orthodontic brackets and archwires made of SS and Ni-Ti. Based on these results, chlorhexidine-containing mouthrinses may be prescribed as non-destructive prophylactic agents on materials evaluated in the present study for orthodontic patients.

2013-01-01

20

Microleakage and shear bond strength of orthodontc brackets bonded to hypomineralized enamel following different surface preparations  

PubMed Central

Objectives: This study investigated the effects of several conditioning methods on shear bond strength (SBS) and microleakage of orthodontic brackets bonded to demineralized enamel. Study Design: One hundred premolars were selected and immersed in a cariogenic solution for 12 weeks. The teeth were randomly assigned into 5 groups. In groups 1 and 2, the teeth underwent acid etching for 30 and 120 seconds, respectively. In group 3, a combination of laser and acid etching was employed. A self-etch primer (SEP) was applied in group 4 and in group 5, the teeth were exposed to acidulated phosphate fluoride (APF) for 4 minutes before etching. After bracket bonding, the teeth were immersed in methylen blue for 12 hours and then were mounted in acrylic resin. SBS was determined with an Instron Universal Testing Machine and the amount of microleakage under the brackets was assessed under a stereomicroscope. Results: The lowest SBS was related to the SEP group and the highest one was observed in the specimens prepared by APF+acid etching. There was a significant difference in SBS (p=0.009), but not in microleakage (p=0.971) of the study groups. The SBS of the specimens treated with SEP was significantly Lower than the other groups, which were not significantly different from each other. The SEP group displayed a higher frequency of bond failure at the enamel-adhesive interface. Conclusions: Enamel preparation with SEP provided the lowest SBS among the groups. All groups showed some degree of microleakage. There was no significant correlation between SBS and microleakage. Key words:Bond strength, microleakage, bonding, self-etch primer, Er:YAG laser.

Shahabi, Mostafa; Mohamadipour, Hamideh; Moosavi, Horieh

2014-01-01

21

Microleakage under orthodontic brackets bonded with the custom base indirect bonding technique.  

PubMed

The aim of this in vitro study was to compare microleakage of orthodontic brackets between enamel-composite and composite-bracket interfaces at the occlusal and gingival margins, bonded using indirect bonding systems with that of a conventional direct bonding method. Forty freshly extracted human maxillary premolar teeth were randomly divided into two groups. In group 1, the brackets were bonded to teeth directly according to the manufacturer's recommendations. Group 2 consisted of 20 teeth bonded indirectly with Transbond XT (3M-Unitek), as the adhesive, and Sondhi Rapid Set A/B Primer (3M-Unitek), a filled resin primer. After bonding, the specimens were further sealed with nail varnish, stained with 0.5 per cent basic fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage at the enamel-composite and composite-bracket interfaces from both the occlusal and gingival margins. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction. The gingival sides of group 1 displayed a higher median microleakage score than the occlusal side at the enamel-composite interface but this was not statistically significant (P > 0.05). All occlusal margins in both groups showed no microleakage under orthodontic brackets at the enamel-composite or composite-bracket interfaces. Comparisons of the microleakage scores between the direct and the indirect bonding groups at the enamel-composite and composite-bracket interfaces indicated no statistically significant microleakage differences at the gingival and occlusal margins (P > 0.05). The type of bonding method (direct versus indirect) did not significantly affect the amount of microleakage at the enamel-composite-bracket complex. PMID:19752016

Yagci, Ahmet; Uysal, Tancan; Ulker, Mustafa; Ramoglu, Sabri Ilhan

2010-06-01

22

Different corrosive effects on hydroxyapatite nanocrystals and amine fluoride-based mouthwashes on dental titanium brackets: a comparative in vitro study  

PubMed Central

Titanium plates treated in vitro with a mouthwash containing amine fluoride (100 ppm F?) and another containing zinc-substituted carbonate–hydroxyapatite have been analyzed by scanning electron microscopy and atomic force microscopy to evaluate the modification of the surface roughness induced by treatment with these two different mouthwashes. The treatment with F?-based mouthwash produces a roughness characterized by higher peaks and deeper valleys in the streaks on the titanium bracket surface compared with those observed in the reference polished titanium plates. This effect causes a mechanical weakness in the metallic dental implant causing bacterial growth and therefore promotes infection and prosthesis contamination. However, the in vitro treatment with a mouthwash containing zinc-substituted carbonate–hydroxyapatite reduced the surface roughness by filling the streaks with an apatitic phase. This treatment counteracts the surface oxidative process that can affect the mechanical behavior of the titanium dental implant, which inhibits the bacterial growth contaminating prostheses.

Lelli, Marco; Marchisio, Olivia; Foltran, Ismaela; Genovesi, Annamaria; Montebugnoli, Giulia; Marcaccio, Massimo; Covani, Ugo; Roveri, Norberto

2013-01-01

23

The effect of different bonding and debonding techniques on debonding ceramic orthodontic brackets.  

PubMed

Previous studies have indicated that different bonding and debonding techniques affect the removal or detachment of polycrystalline ceramic brackets that use a mechanical mechanism of bonding to resin. The delamination type debonding forces have been shown to be more effective, compared with twisting and tensile type forces. Further, polycrystalline brackets bonded by the indirect techniques debond leaving minimal filled resin on the tooth surface and hence cleanup and enamel damage are minimized. The purpose of this research was to compare the effects of three bonding and debonding techniques on debonding two types of ceramic brackets, using different modes of bonding. The monocrystalline bracket used the chemical and the polycrystalline bracket used the mechanical mechanisms for bonding respectively. Brackets were bonded to 180 freshly extracted bovine teeth, divided into two groups of 90 each, based on the bracket employed, i.e., monocrystalline and polycrystalline brackets. These brackets were bonded with the direct and two different indirect bonding methods: the conventional indirect method (modified Thomas) and the indirect technique that used a thermally cured resin. Each bonding group was further divided into three groups of 10, based on the type of debonding technique used, i.e., lift off, delamination, and twisting. The variables evaluated were bracket failure and remnant adhesive on debonding. The data were subjected to an analysis of variance to determine existence of significant differences, followed by multiple comparisons of means. Bracket failure or fracture was significantly affected, based on the bonding technique and the debonding technique for the monocrystalline at p < 0.0001 and the polycrystalline ceramic brackets at p < 0.001 and p < 0.05, respectively. Remnant adhesive was significantly affected by bonding and debonding techniques for the polycrystalline brackets at p < 0.0001. Remnant adhesive was significantly (p < 0.01) affected by the bonding technique for the monocrystalline brackets. The delamination debonding technique combined with the thermal-cured indirect bonding technique was shown to be a safe combination for debonding both types of ceramic brackets. Therefore both bonding and debonding techniques significantly affect bracket failure or fracture and remnant adhesive of ceramic orthodontic brackets during the debonding procedure. PMID:9267223

Sinha, P K; Nanda, R S

1997-08-01

24

Effect of surface treatment with sandblasting and Er,Cr:YSGG laser on bonding of stainless steel orthodontic brackets to silver amalgam  

PubMed Central

Objectives: Satisfactory bonding of orthodontic attachments to amalgam is a challenge for orthodontists. The aim of this in vitro study was to compare the shear bond strength of stainless steel orthodontic brackets to silver amalgam treated with sandblasting and Er,Cr:YSGG laser. Study Design: Fifty-four amalgam discs were prepared, polished and divided into three groups: In group 1 (the control group) the premolar brackets were bonded using Panavia F resin cement without any surface treatment; in groups 2 and 3, the specimens were subjected to sandblasting and Er,Cr:YSGG laser respectively, before bracket bonding. After immersing in distilled water at 37°C for 24 hours, all the specimens were tested for shear bond strength. Bond failure sites were evaluated under a stereomicroscope. Data was analyzed using one-way ANOVA and a post hoc Tukey test. Results: The highest and lowest shear bond strength values were recorded in the laser and control groups, respectively. There were significant differences in mean shear bond strength values between the laser and the other two groups (p<0.05). However, there were no significant differences between the sandblast and control groups (p=0.5). Conclusions: Amalgam surface treatment with Er,Cr:YSGG laser increased shear bond strength of stainless steel orthodontic brackets. Key words: Amalgam, surface treatment, shear bond strength, sandblasting, Er,Cr:YSGG laser.

Kachoei, Mojgan; Rikhtegaran, Sahand; Fathalizadeh, Farzaneh; Navimipour, Elmira J.

2012-01-01

25

Load-deflection and surface properties of coated and conventional superelastic orthodontic archwires in conventional and metal-insert ceramic brackets  

PubMed Central

Background: Properties of coated archwires, which have been introduced for esthetic demands during orthodontic treatments, along with the use of tooth-colored brackets, are not clear. The aim of this study is to compare the load-deflection and surface properties of coated superelastic archwires with conventional superelastic archwires in conventional and metal-insert ceramic brackets. Materials and Methods: In this experimental study, 3 types of archwires including ultraesthetic polycoated, ultraesthetic epoxyresin coated and conventional (uncoated) superelastic nickel-titanium (NiTi) archwires were used in each of 2 types of brackets including conventional and metal-insert ceramic. To simulate oral environment, all specimens were incubated in artificial saliva using thermocycling model and then were tested in three-bracket bending test machine. Loading and unloading forces, plateau gap and end load deflection point (ELDP) were recorded. Archwires were investigated with a stereomicroscope before and after the experiment. Two-way ANOVA and Tukey tests were used at P<0.05. Results: Epoxyresin archwires produced lower forces (19 to 310 gr) compared to polycoated (61 to 359 gr) and NiTi (61 to 415 gr) (P<0.0001). The maximum ELDP (0.43 mm) was observed in epoxyresin archwires (P<0.001). Coatings of some epoxyresin wires were torn and of polycoated wires peeled off. Conventional ceramic bracket produced higher loading forces with polycoated and NiTi archwires and lower unloading forces with all 3 types of archwires compared to metal-insert type (P<0.05). Conclusion: Epoxyresin-coated archwire had the lowest force and highest ELDP. Coatings were not durable in these experimental conditions. Conventional ceramic bracket produced higher frictional force compared to metal-insert type.

Alavi, Shiva; Hosseini, Navid

2012-01-01

26

Bracketing Mid-Pliocene Sea Surface Temperature: Maximum and Minimum Possible Warming  

Microsoft Academic Search

Abstract Estimates,of sea,surface,temperature,(SST) from,ocean,cores,reveal awarm,phase ,of the ,Pliocene ,between ,about ,3.3 and ,3.0 Mega- annum’s (Ma). Pollen records from land based cores and sections, although not as well dated, also show evidence for a warmer climate atabout,the,same,time.,Increased,greenhouse,forcing,and,altered ocean,heat ,transport ,is the ,leading ,candidates ,for the ,underlying cause of Pliocene global warmth. However, despite being a period of global warmth, there

Harry Dowsett

27

Comparison of ion release from new and recycled orthodontic brackets  

Microsoft Academic Search

Bracket corrosion can occur in the oral environment. The purpose of this study was to compare the release of metal ions from new and recycled brackets in artificial saliva and buffers with different pH values over a 12-week immersion period. The brackets were divided into 2 groups: new and recycled. The recycled bracket bases were coated with adhesive and the

Tsui-Hsien Huang; Chen-Chieh Yen; Chia-Tze Kao

2001-01-01

28

Effects of surface treatment and artificial aging on the shear bond strength of orthodontic brackets bonded to four different provisional restorations.  

PubMed

ABSTRACT Objective: To evaluate the combined effects of material type, surface treatment, and thermocycling on the bond strength of orthodontic brackets to materials used for the fabrication of provisional crowns. Materials and Methods: Four materials were included in this study (ProTemp, Trim Plus, Trim II, and Superpont C+B). Sixty cylindrical specimens (1 × 3 cm) were prepared from each material and equally divided into three groups. The first group was ground with silica carbide paper, the second was polished with pumice, and the last group was sandblasted with 50-µm aluminum oxide particles. Stainless-steel maxillary central incisor brackets (Victory Series, 3M) were bonded to the provisional material specimens with Transbond XT light-cured composite resin, and half of the specimens from each group were thermocycled 500 times in 5°C and 55°C water baths. Then the brackets were debonded with shear testing, and the results were statistically analyzed by three-way analysis of variance and Tukey's multiple-comparison tests at ? ?=? 0.05. Adhesive Remnant Index (ARI) was also identified. Results: Before and after thermocycling, ProTemp materials showed the highest shear bond strength with orthodontic brackets (10.3 and 13.1 MPa, respectively). The statistical analysis indicated an interaction among the three independent variables (P < .05) and statistically significant differences in bond strength among provisional materials (P < .001), surface treatments (P < .001), and thermocycling (P < .05). According to the ARI, most groups demonstrated adhesive failure. Conclusions: The provisional material type, surface treatment, and artificial aging have a significant effect on bond strength. Sandblasting treatment exerts a beneficial effect on shear bond strength. PMID:24446920

Al Jabbari, Youssef S; Al Taweel, Sara M; Al Rifaiy, Mohammed; Alqahtani, Mohammed Q; Koutsoukis, Theodoros; Zinelis, Spiros

2014-07-01

29

Metallographic Structure andHardness of Titanium Orthodontic Brackets  

Microsoft Academic Search

Aim: To determine the elemental composition, microstructure, and hardness of two different brands of titanium (Ti) orthodontic brackets. Materials and Methods: Four specimens of each brand were embedded in epoxy resin and, after metallographic grinding and polishing, were studied under a metallographic microscope. The bonding base morphology of each bracket was studied in as-received brackets by scanning electron microscopy. Energy

Spiros Zinelis; Olga Annousaki; Theodore Eliades; Margarita Makou

2003-01-01

30

A simple bracket placement gauge.  

PubMed

Various techniques for placement of orthodontic brackets have been described. Metallic jigs or instruments are available for bracket placement at a desired height. The present article describes a simple bracket placement gauge to position the brackets accurately during bonding procedure. PMID:24358652

Hattarki, Rohan S

2013-01-01

31

Laboratory evaluation of modern plastic brackets.  

PubMed

The aim of the study was to evaluate some properties of modern orthodontic plastic brackets. Seven bracket brands [Aesthetik-Line (AL), Avalon (AV), Brillant (BR), Elegance (EL), OrthoFlex (OF), Silkon Plus (SL), and Spirit MB (SP)] were included in the study. The properties tested were chemical composition, base morphology, slot roughness, Vickers hardness (VH), and shear bond strength (SBS) with enamel.According to the results, the brackets were composed of polyurethane (AV and OF), polyoxymethylene (BR), and Ca-Al-silicate fibre glass-reinforced polycarbonate (AL, EL, SL, and SP). Metallic slots were composed of austenitic stainless steel (EL and SP) and Ag-Cu alloy (AV). The base morphology exhibited distinct designs, employing parallel retentive canals (AV, EL, and OF) or round-angled square protrusions with major retentive elements (AL, BR, and SP) or a combination of both (SL). The SP metallic slot demonstrated the lowest Sz values. No significant differences were found in VH among the brackets before water immersion (19.6-16.9 VH). After 12 weeks immersion, the brackets showed a significant hardness reduction (16.6-12.9 HV). SBS ranged between 111 and 193 N (8-14 MPa) for all brackets, except from SP (59 N/5 MPa). The predominant failure mode was mixed adhesive and cohesive. Most of the plastic brackets presented a base structure capable of adequate bonding to enamel, regardless of their differences in composition. Slot roughness showed differences among groups. All the brackets demonstrated plasticization after prolonged water storage. PMID:21750238

Ali, Omar; Makou, Margarita; Papadopoulos, Triantafillos; Eliades, George

2012-10-01

32

Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets  

PubMed Central

Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the method showing the highest SBS was selected. A New group (VI) was recycled twice with the selected method. Six subgroups (1-6) were established; the primer was applied for three sub-groups, and the composite was applied for all brackets. Brackets were subjected to the same shear force, and SBS was measured for all sub-groups. Results: There was a significant difference between the mean SBS of the sandblasting method and the means of SBS of each of the other three methods. There was however, no significant difference between the mean SBS of the new bracket and the mean SBS of recycled bracket using sandblasting. The mean SBS of all sub-groups were more than that recommended by Reynolds (17) in 1975. Brackets with primer showed slightly higher SBS compared to those of brackets without bonding agent. Conclusion: To decrease cost, sandblasted recycled orthodontic brackets can be used as an alternative to new brackets. It is recommended to apply a bonding agent on the bracket base to provide greater bond strength. Key words:Recycled bracket, shear bond strength, sandblasting, stainless steel orthodontic bracket.

Bahnasi, Faisal I.; Abu-Hassan, Mohame I.

2013-01-01

33

Bracketing of Probable Atmospheric Wind Conditions through a Family of Surface Layers and Sensitivities of a Building-Model Flowfield.  

National Technical Information Service (NTIS)

A family of simulated atmospheric surface layers, covering a wide range of mean profile exponents, were used to examine the response of the flowfield around a building model to variations in the characteristics of the turbulent layers. Salient features in...

H. M. Nagib T. C. Corke J. Tan-atichat

1976-01-01

34

A study of the development of a new type of bulb bracket for offshore structures using suitable casting steel  

NASA Astrophysics Data System (ADS)

In this study, the optimum structural design of brackets for offshore structures was carried out through the ANSYS program. We wished to propose a new type of bulb bracket made by a casting process compared with the built-up type of bracket. For a better structural design of the bracket, we can't adopt face plate but stiffener and circular type shape at the diagonal surface line. Under the new type of bulb bracket made by a casting process, it was possible to reduce the size by about 30% and the weight by about 50% compared with the face-plate type of bracket.

Kim, Tae-Won; Kang, Chung-Gil; Park, Sang-Sik

2010-06-01

35

Orthodontic Bracket Manufacturing Tolerances and Dimensional Differences between Select Self-Ligating Brackets  

PubMed Central

In all manufacturing processes there are tolerances; however, orthodontic bracket manufacturers seldom state the slot dimensional tolerances. This experiment develops a novel method of analyzing slot profile dimensions using photographs of the slot. Five points are selected along each wall, and lines are fitted to define a trapezoidal slot shape. This investigation measures slot height at the slot's top and bottom, angles between walls, slot taper, and the linearity of each wall. Slot dimensions for 30 upper right central incisor self-ligating stainless steel brackets from three manufacturers were evaluated. Speed brackets have a slot height 2% smaller than the nominal 0.559?mm size and have a slightly convergent taper. In-Ovation brackets have a divergent taper at an average angle of 1.47 degrees. In-Ovation is closest to the nominal value of slot height at the slot base and has the smallest manufacturing tolerances. Damon Q brackets are the most rectangular in shape, with nearly 90-degree corners between the slot bottom and walls. Damon slot height is on average 3% oversized.

Major, Thomas W.; Carey, Jason P.; Nobes, David S.; Major, Paul W.

2010-01-01

36

[The effect of the vertical bracket position on the orthodontic finish].  

PubMed

As during orthodontic treatment and in particular during the phase of the precise adjustment of occlusion by applying the "straight-wire technique" problems arise as far as the vertical dimensions are concerned, the usual distances between the bracket slots and the edges of the incisors respectively the top of the cusps have been verified. Measurements were done on models at the end of treatment of ten patients treated with fixed attachments who may represent ideal occlusion as far as profile radiographs and gnathology were concerned. After regulation of the plane of occlusion the vertical distances between the slot base plane (parallel to the plane of occlusion) and the edge of the incisors respectively tops of cusps were measured by means of a modified parallelometer in connection with a special slot and tube support as well as a specially developed dial test indicator, while a maximum fit between bracket base and buccal crown surface was given. In case of the upper front brackets (torque + 22 degrees) large vertical measurement to the edge of the incisors were recorded, 8.25 respectively 8.33 mm). This may be attributable to excessive torque of the applied brackets. Only approximate figures for the vertical positioning for other teeth could be given, as anatomical variations have to be considered. PMID:2227734

Muchitsch, A P; Droschl, H; Bantleon, H P; Blumauer, D; Stern, G

1990-08-01

37

A pilot study for evaluation of bond strength of orthodontic brackets to enamel using a new impact test machine.  

PubMed

We report an in-vitro pilot study to assess the ability of a new impact test machine to evaluate bond strength of orthodontic brackets to tooth enamel. A total of 37 extracted premolar teeth were bonded with APC Plus MBT Victory orthodontic brackets. Bond strength was tested using a new pendulum-based instrumented impact test machine. The maximum stress, the impact energy and interaction time required to debond the brackets were recorded. Of the total tested, 9 samples were successfully debonded with no obvious damage to the tooth surface although 28 samples fractured through the enamel and dentine. There was a statistically significant difference between the maximum stress required to debond the bracket and that required to fracture the tooth, a higher stress being required to debond the bracket. Significantly less stress was required to fracture older teeth. The high incidence of tooth fracture suggests a need to modify the impact test protocol. The lack of a simulated periodontal ligament, which is present clinically and acts as a shock absorber, may have contributed to the high failure rate, although the striking position of the pendulum also needs to be considered. PMID:18376018

Hendry, R E; Gilgrass, T; Chung, L; MacPherson, R; Yang, T H J; Reuben, R L

2008-01-01

38

[Hardened anodized aluminum as a replacement material for bracket manufacture].  

PubMed

Attention has been repeatedly drawn to the problem of corrosion and the risk of allergic reaction to nickel resulting from the use of stainless steel brackets. In the search for a suitable alternative, manufacturers have turned to thin coating technology using hardened anodized aluminium. Applying resistance to corrosion and abrasion as the criteria to be met, they have selected aluminium alloy type 6082 as the material of choice. Purpose of this study is to examine the physical suitability of this material. Using the above noted alloy, 60 prototype brackets were made with a hardened anodized surface. They were then subjected to the following 3 stress tests: first an abrasion test using a tooth polishing machine, second, a deformation test using a device designed to simulate torque movement, and, third, a corrosion test. The effects on the brackets resulting from the three types of stress were evaluated by light microscopy. A quantitative analysis of the corrosion test was performed by ICP spectrometry. The control group consisted of conventional stainless steel brackets. The light microscopic analysis revealed no evidence of surface damage or signs of deformation in the prototype brackets. The steel brackets, on the other hand, showed clear signs of wear and corrosion. The quantitative analysis of the corrosion solution revealed metallic ion wear of 1.75 ng x mm-2 x h-1 for the prototypes subjected to abrasion. The steel brackets showed at a factor of around 104.6 metallic ion wear of 183 ng x mm-2 x h-1. In addition to this, no Ni ions were found in the corrosion solution of the prototype brackets.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7851828

Fischer-Brandies, H; Bönhoff, M

1994-12-01

39

Frictional properties of aesthetic brackets  

Microsoft Academic Search

SUMMARY The purpose of this study was to compare the frictional properties of two self-ligating aesthetic brackets, Opal (Ultradent Products) and Oyster (Gestenco Int.), with those of four conventionally ligated aesthetic brackets, Transcend (3M Unitek), Inspire (Ormco), Allure (GAC Int.), and Image (Gestenco Int.). Friction was tested with different wire dimensions and qualities (stainless steel (SS) wire 0.017 × 0.025

C. A. Reicheneder; U. Baumert; T. Gedrange; P. Proff; A. Faltermeier; D. Muessig

2007-01-01

40

Heat generated by grinding during removal of ceramic brackets.  

PubMed

When ceramic brackets fracture during treatment or at the time of debonding, it may become necessary to remove residual fragments by grinding with a handpiece. However, the grinding of ceramic surfaces may generate temperatures high enough to have detrimental effects on dental pulp. Intrapulpal temperature measurements were made on extracted teeth during bracket grinding with a small thermocouple probe fixed to the pulpal wall subjacent to the bracket position. These measurements were then compared with established threshold temperatures that have been reported to cause pulpal pathosis. We removed 122 ceramic brackets (A-Company Starfire, GAC Allure, and Unitek Transcend) from eight extracted teeth by grinding with high-speed diamond burs or low-speed green stones, both with and without air or water coolant. It was determined that low-speed grinding without coolant resulted in a significant (p less than 0.001) increase in pulp chamber temperature for all three types of brackets. Neither high-speed nor low-speed grinding during bracket removal caused a rise in pulp chamber temperature when combined with air or water coolant. PMID:1645495

Vukovich, M E; Wood, D P; Daley, T D

1991-06-01

41

A comparative evaluation of the retention of metallic brackets bonded with resin-modified glass ionomer cement under different enamel preparations: A pilot study  

PubMed Central

Introduction: For orthodontists, the ideal bonding material should be less moisture-sensitive and should release fluoride, thereby reducing unfavorable iatrogenic decalcification. Resin-Modified Glass Ionomer Cements (RMGICs), due to their ability to bond in the presence of saliva and blood can be a very good bonding agent for orthodontic attachments especially in the areas of mouth, which are difficult to access. Moreover, their fluoride releasing property makes them an ideal bonding agent for patients with poor oral hygiene. However, their immediate bond strength is said to be too low to immediately ligate the initial wire, which could increase the total number of appointments. The effect of sandblasting and the use of sodium hypochlorite (NaOCL) on the immediate bond failure of RMGIC clinically have not been reported in the literature until the date. This investigation intended to assess the effect of sandblasting (of the bracket base and enamel) and NaOCL on the rate of bond failure (with immediate ligation at 30 min) of Fuji Ortho LC and its comparison with that of conventional light cured composite resin over a period of 1 year. Materials and Methods: 400 sample teeth were further divided into 4 groups of 100 each and bonded as follows: (1) Group 1: Normal metallic brackets bonded with Fuji Ortho LC. (2) Group 2: Sandblasted bracket base and enamel surface, brackets bonded with Fuji Ortho LC. (3) Group 3: Deproteinized enamel surface using sodium hypochlorite and brackets bonded with Fuji Ortho LC. (4) Group 4: Normal metallic bracket bonded with Transbond XT after etching enamel with 37% phosphoric acid. This group served as control group. Results and Conclusion: Results showed that sandblasting the bracket base and enamel, can significantly reduce the bond failure rate of RMGIC.

Sharma, Padmaja; Valiathan, Ashima; Arora, Ankit; Agarwal, Sachin

2013-01-01

42

The friction and wear patterns of orthodontic brackets and archwires in the dry state.  

PubMed

Frictional resistance at the bracket-archwire interface has been demonstrated to impede tooth movement when sliding mechanics are used. Thus, the coefficients of friction of titanium and stainless steel brackets used in conjunction with stainless and ion-implanted beta-titanium archwires were investigated using a single contact interface between the brackets and archwires. The wear patterns between the brackets and the.016- in flat archwire surfaces were also examined using scanning electron microscopy and energy dispersive x-ray analysis. Stainless steel brackets tested with. 016-in flat stainless steel wire surfaces recorded the lowest coefficient of static friction mean (0.289), whereas titanium brackets paired with.016-in flat ion-implanted beta-titanium wire surfaces produced the highest mean (0.767). Stainless steel brackets had significantly (P <.05) lower coefficients of friction than titanium brackets for all wires except.020-in round stainless steel wires. Ion-implanted beta-titanium wires generally had significantly larger coefficients of friction than stainless steel wires. The increased friction of the titanium and ion-implanted beta-titanium alloys is also reflected in the severity of their wear patterns. An inverse relationship between friction and archwire surface dimension was generally found for ion-implanted beta-titanium wires. Round stainless steel wires demonstrated lower coefficients of kinetic friction than the flat stainless steel wire surfaces. PMID:11113802

Michelberger, D J; Eadie, R L; Faulkner, M G; Glover, K E; Prasad, N G; Major, P W

2000-12-01

43

Surface Based Differential Forms  

SciTech Connect

Higher-order basis functions have been constructed for surface-based differential forms that are used in engineering simulations. These surface-based forms have been designed to complement the volume-based forms present in EMSolve[1], a finite element code. The basis functions are constructed on a reference element and transformed, as necessary, for each element in space. Lagrange polynomials are used to create the basis functions. This approach is a necessary step in creating a hybrid finite-element/integral-equation time-domain code for electromagnetic analysis.

Pingenot, J; Yang, C; Jandhyala, V; Champagne, N; White, D; Stowell, M; Rieben, R; Sharpe, R; Madsen, N; Fasenfest, B J; Rockway, J D

2004-12-14

44

An in vitro comparison of the frictional forces between archwires and self-ligating brackets of passive and active types.  

PubMed

The aim of this study was to compare the static and kinetic frictional forces generated by various contemporary designs of self-ligating brackets (SLBs) and different wire alloys. In total, six different brackets (four passive type SLB, one active SLB, and one conventional bracket) were investigated using stainless steel, nickel-titanium, and titanium-molybdenum alloy archwires of several sizes. The friction forces were measured by sliding on a bracket-wire combination system in an EZ instron testing machine. A scanning electron microscope (SEM) was used to examine the wear effects of the wall surfaces of bracket slots. Energy-dispersive spectroscopy (EDS) was used to identify the elemental compositions of the bracket surfaces. The data were collected and statistically analysed using analysis of variance. The results of static and kinetic frictional forces were lower in passive type SLBs (P < 0.05), except in the Smart Clip bracket. The wire materials or wire dimensions in the present study showed similar friction forces with no statistical differences (P > 0.05). The wearing effects were not obviously found in bracket slots under SEM observation. Only conventional brackets and mini-Clippy SLB revealed nickel ions via EDS analysis. This study shows that passive SLBs are associated with lower static or kinetic friction forces than those of active SLBs or conventional brackets. Wear on the bracket slots was not observed in the present study. PMID:21765175

Huang, Tsui-Hsien; Luk, Hoi-Shing; Hsu, Ying-Chi; Kao, Chia-Tze

2012-10-01

45

Evaluation of titanium brackets for orthodontic treatment: part I. The passive configuration.  

PubMed

The static and kinetic frictional coefficients of commercially pure titanium brackets were evaluated in the passive configuration in the dry and wet states against stainless steel, nickel-titanium, and beta-titanium arch wires. For comparison, stainless steel brackets were evaluated under identical conditions. Titanium brackets were grayer in color and rougher in texture than the stainless steel brackets. Bracket slots were up to 0.002 inch greater than the nominally stated values. Remarkably, the static and kinetic frictional coefficients of the couples formed by titanium and stainless steel brackets were comparable. When evaluated against stainless steel and nickel-titanium arch wires in the dry state at 34 degrees C, the static coefficient averaged.12 and.20, respectively, independent of bracket alloy. When evaluated against stainless steel and nickel-titanium wires in the wet state at 34 degrees C using human saliva, the static coefficient averaged.15 and.20, respectively, independent of bracket alloy. Only the beta-titanium arch wires increased by about 15%, when tested in either the dry or the wet state against titanium versus stainless steel brackets. Noteworthy, too, was the decrease of both coefficients in the beta-titanium wire couples from their previously reported values. Analyses of electron spectroscopy for chemical analysis spectra and depth profiles show that these new brackets are titanium only in the bulk. Indeed the immediate surfaces are composed of, at least, 80 atomic percent (at.%) carbon and oxygen; whereas, the titanium that is present (>11 at.%) is mostly in the form of titanium dioxide. The presence of this quite thin passivating layer, which resides on top of an oxygen-hardened titanium substrate, reduces the galling and fretting that would normally be expected in such materials. Pending the outcome of future angulation tests, these frictional measurements show that titanium brackets are not only comparable to stainless steel brackets but also are more biocompatible with nickel having been eliminated from their constitution. PMID:9810052

Kusy, R P; Whitley, J Q; Ambrose, W W; Newman, J G

1998-11-01

46

Direct light transmittance through ceramic brackets  

Microsoft Academic Search

The objective of this study was to investigate the degree of direct light transmittance (%T) of various types of esthetic brackets and to correlate these values with their structure, morphologic factors, and composition. Eight types of brackets were used in the study; six brackets of each type were tested. An ultraviolet-visible spectroscopic direct transmission analysis was performed at 320 to

Theodore Eliades; William M. Johnston; George Eliades

1995-01-01

47

Prevention of demineralization around orthodontic brackets using two different fluoride varnishes  

PubMed Central

Objective: This in-vitro study was done to evaluate the effects of two different seal materials, Duraflor™ and Enamel Pro® Varnish, on enamel demineralization adjacent to orthodontic fixed appliances. Methods: Seventy-two extracted solid premolars were allocated to three groups as one control and two study groups after brackets were placed and bonded with Transbond™ XT. The control group received no topical fluoride application after bonding, whereas in the study groups two fluoride varnishes, Enamel Pro® Varnish and Duraflor™ were applied on the teeth adjacent to brackets. All specimens were then immersed separately in demineralization solution for 96 hours at constant temperature. Demineralization of the enamel surface was evaluated quantitatively by cross-sectional microhardness testing: indentations were made at the edge of the bracket base (0 ?m) and at 100 and 200 ?m distant from it. In all of these positions, 5 indentations were made at 10, 20, 40, 70 and 90 ?m of depths from the external surface of the enamel. Results: The results revealed that, Enamel Pro® Varnish and Duraflor™ group values are higher than the values of control group at every depth. The differences between the depths showed that the microhardness values decreased significantly when the depth increased. In the control group, more demineralization occurred in every indentation compared to the study group. Conclusion: Duraflor™ and Enamel Pro® Varnish can be considered for use in clinic as an effective method to prevent or reduce demineralization during orthodontic treatment, especially in patients with poor oral hygiene.

Nalbantgil, Didem; Oztoprak, Mehmet Oguz; Cakan, Derya Germec; Bozkurt, Kemal; Arun, Tulin

2013-01-01

48

Surface Plasmon Based Spectrometer  

NASA Astrophysics Data System (ADS)

A spectrometer that uses surface plasmon excitation in thin metal films to separate light into its component wavelengths is described. The use of surface plasmons as a dispersive medium sets this spectrometer apart from prism, grating, and interference based variants and allows for the miniaturization of this device. Theoretical and experimental results are presented for two different operation models. In the first case surface plasmon tunneling in the near field is used to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution as well as absorption spectra of chlorophyll extracted from a spinach leaf. The second model looks at the far field components of surface plasmon scattering.

Wig, Andrew; Passian, Ali; Boudreaux, Philip; Ferrell, Tom

2008-03-01

49

A New Carbide Finishing Bur for Bracket Debonding  

Microsoft Academic Search

Background: The removal of residual bonding resin with rotary instruments after bracket debonding may damage the enamel surface. Conventional carbide burs may scratch the enamel due to the shape and sharpness of their blades. Carbide Finishing Bur: A new carbide finishing bur with a slightly tapered shape, rounded tip and eight twisted blades has been developed. As a special feature

Ralf J. Radlanski

2001-01-01

50

Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study.  

PubMed

Objective: The aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires. Material and Methods: Seventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide® elastomeric ligature. Results: The results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface. Conclusion: The levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to reduce friction. PMID:25025560

Mendes, Bernardo de Azevedo Bahia; Ferreira, Ricardo Alberto Neto; Pithon, Matheus Melo; Horta, Martinho Campolina Rebello; Oliveira, Dauro Douglas

2014-06-01

51

Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study  

PubMed Central

Objective The aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires. Material and Methods Seventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide® elastomeric ligature. Results The results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface. Conclusion The levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to reduce friction.

MENDES, Bernardo de Azevedo Bahia; FERREIRA, Ricardo Alberto Neto; PITHON, Matheus Melo; HORTA, Martinho Campolina Rebello; OLIVEIRA, Dauro Douglas

2014-01-01

52

Effect of fluoride on friction between bracket and wire  

PubMed Central

Background: Friction is usually encountered during sliding technique for orthodontic space closure. This study aims to investigate the effect of fluoride on frictional resistance between stainless steel orthodontic brackets and steel and NiTi arch wires. Materials and Methods: A total of 144 standard 022 stainless steel brackets were used in this experimental study. 0.016 and 0.019 × 0.025 inch steel and NiTi arch wires were tested. The frictional resistance between wires and brackets immersed in the following three solutions were measured: Sultan fluoride gel containing 1.23% acidulated phosphate fluoride at pH 3.5 for 4 minutes, aquafresh mouth wash containing 0.05% sodium fluoride at pH of 5.1 for 1 minute twice a day for 8 weeks and physiologic serum (pH=7) as the control group. Static and dynamic frictional forces were measured using Testometric machine. Surface topography of wires and brackets was qualitatively assessed using electron microscopy. Three-way and two-way variance analysis and complementary Tuckey analysis were applied to compare the groups for any significant differences (P<0.05). Results: The average static and dynamic frictional forces for all bracket-wire combinations immersed in Sultan fluoride gel were higher than those immersed in NAF and control groups (P<0.001).The forces measured for rectangular wires were higher than round wires (P<0.001). Frictional resistance of 0.016 inch NiTi wire was more than that of the steel one but the difference between steel and NiTi 0.019 × 0.25 arch wires was not significant. Conclusion: Friction between steel brackets and nickel titanium and steel wires is affected by prophylactic agents containing high doses of fluoride and acidity.

Alavi, Shiva; Farahi, Ali

2011-01-01

53

Enhanced mycelial biomass production of the hairy bracket mushroom, Trametes hirsuta (Higher Basidiomycetes), by optimizing medium component with Plackett-Burman design and response surface methodology.  

PubMed

Statistical analyses based on experimental designs were applied to optimize the medium components for mycelial biomass production by Trametes hirsuta in shake flask cultivation. First, the effects of different carbon resources (glucose, sucrose, lactose, maltose, fructose, soluble starch and potato), nitrogen resources (yeast extract, peptone, (NH4)2SO4, NH4NO3, NH4Cl, peanut powder, soybean powder) and mineral elements (CaCl2, ZnSO4·7H2O, FeSO4·7H2O, MnSO4·H2O, CuSO4·7H2O) on mycelial biomass production were investigated using a univariate design. Second, a Plackett-Burman design was applied to identify the significant variables that principally influenced the mycelial biomass production, and the path of steepest ascent was pursued to approach the regions of optimal value of the significant variables. Subsequently, these significant variables were optimized using the Box-Behnken design of response surface methodology. Ultimately, the optimized medium conditions were composed of sucrose 25.65 g·L-1, MgSO4·7H2O 1.24 g·L-1, and FeSO4·7H2O 3.36 g·L-1, and the yield of mycelial biomass reached 15.45 g·L-1, which represents an approximately 1.6-fold increase above the initial yield. PMID:24266383

Yang, Rongling; Liu, Xueming; Zhao, Xiangjie; Xu, Yujuan; Ma, Rongxia

2013-01-01

54

Investigation of bracket bonding for orthodontic treatments using en-face optical coherence tomography  

NASA Astrophysics Data System (ADS)

Despite good diagnosis and treatment planning, orthodontic treatment can fail if bonding fails. It is now common practice to address the aesthetic appearance of patients using aesthetic brackets instead of metal ones. Therefore, bonding aesthetic brackets has become an issue for orthodontists today. Orthodontic bonding is mainly achieved using composite resin but can also be performed with glass ionomer or resin cements. For improving the quality of bonding, the enamel is acid etched for 30 seconds with 38% phosphoric acid and then a bonding agent is applied. In our study we investigated and compared the quality of bonding between ceramic brackets, polymeric brackets and enamel, respectively using a new investigation method-OCT. The aim of our study was to evaluate the resin layer at the bracket base-tooth interface.

Sinescu, Cosmin; Negrutiu, Meda L.; Hughes, Michael; Bradu, Adrian; Todea, Carmen; Rominu, Roxana; Dodenciu, Dorin; Laissue, Philippe L.; Podoleanu, Adrian G.

2008-05-01

55

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Orthodontic plastic bracket. 872.5470 Section...Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic...

2009-04-01

56

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Orthodontic plastic bracket. 872.5470 Section...Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic...

2010-04-01

57

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device...

2013-04-01

58

A comparison of shear bond strength of orthodontic brackets bonded with four different orthodontic adhesives  

PubMed Central

Objectives: The objective of this study is to compare the shear bond strength (SBS) of stainless steel (SS) orthodontic brackets bonded with four different orthodontic adhesives. Materials and Methods: Eighty newly extracted premolars were bonded to 0.022 SS brackets (Ormco, Scafati, Italy) and equally divided into four groups based on adhesive used: (1) Rely-a-Bond (self-cure adhesive, Reliance Orthodontic Product, Inc., Illinois, USA), (2) Transbond XT (light-cure adhesive, 3M Unitek, CA, USA), (3) Transbond Plus (sixth generation self-etch primer, 3M Unitek, CA, USA) with Transbond XT (4) Xeno V (seventh generation self-etch primer, Dentsply, Konstanz, Germany) with Xeno Ortho (light-cure adhesive, Dentsply, Konstanz, Germany) adhesive. Brackets were debonded with a universal testing machine (Model No. 3382 Instron Corp., Canton, Mass, USA). The adhesive remnant index (ARI) was recordedIn addition, the conditioned enamel surfaces were observed under a scanning electron microscope (SEM). Results: Transbond XT (15.49 MPa) attained the highest bond strength. Self-etching adhesives (Xeno V, 13.51 MPa; Transbond Plus, 11.57 MPa) showed clinically acceptable SBS values and almost clean enamel surface after debonding. The analysis of variance (F = 11.85, P < 0.0001) and Chi-square (?2 = 18.16, P < 0.05) tests revealed significant differences among groups. The ARI score of 3 (i.e., All adhesives left on the tooth) to be the most prevalent in Transbond XT (40%), followed by Rely-a-Bond (30%), Transbond Plus with Transbond XT (15%), and Xeno V with Xeno Ortho (10%). Under SEM, enamel surfaces after debonding of the brackets appeared porous when an acid-etching process was performed on the surfaces of Rely-a-Bond and Transbond XT, whereas with self-etching primers enamel presented smooth and almost clean surfaces (Transbond Plus and Xeno V group). Conclusion: All adhesives yielded SBS values higher than the recommended bond strength (5.9-7–8 MPa), Seventh generation self-etching primer Xeno V with Xeno Ortho showed clinically acceptable SBS and the least amount of residual adhesive left on the enamel surface after debonding.

Sharma, Sudhir; Tandon, Pradeep; Nagar, Amit; Singh, Gyan P; Singh, Alka; Chugh, Vinay K

2014-01-01

59

Galvanic corrosion between orthodontic wires and brackets in fluoride mouthwashes.  

PubMed

The aim of this investigation was to determine the influence of fluoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution of Fusayama-Meyer artificial saliva and in two commercially available fluoride (250 ppm) mouthwashes, Elmex and Meridol. Corrosion resistance was assessed by inductively coupled plasma-atomic emission spectrometry (ICP-MS), analysis of released metal ions, and a scanning electron microscope (SEM) study of the metal surfaces after immersion of different wire-bracket pairs in the test solutions. The study was completed by an electrochemical analysis. Meridol mouthwash, which contains stannous fluoride, was the solution in which the NiTi wires coupled with the different brackets showed the highest corrosion risk, while in Elmex mouthwash, which contains sodium fluoride, the CuNiTi wires presented the highest corrosion risk. Such corrosion has two consequences: deterioration in mechanical performance of the wire-bracket system, which would negatively affect the final aesthetic result, and the risk of local allergic reactions caused by released Ni ions. The results suggest that mouthwashes should be prescribed according to the orthodontic materials used. A new type of mouthwash for use during orthodontic therapy could be an interesting development in this field. PMID:16428255

Schiff, Nicolas; Boinet, Mickaël; Morgon, Laurent; Lissac, Michèle; Dalard, Francis; Grosgogeat, Brigitte

2006-06-01

60

Frictional resistance of self-ligating versus conventional brackets in different bracket-archwire-angle combinations  

PubMed Central

Objective To compare the influence of archwire material (NiTi, beta-Ti and stainless steel) and brackets design (self-ligating and conventional) on the frictional force resistance. Material and Methods Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M). The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement. Results Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials. Conclusion even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material.

MONTEIRO, Maria Regina Guerra; da SILVA, Licinio Esmeraldo; ELIAS, Carlos Nelson; VILELLA, Oswaldo de Vasconcellos

2014-01-01

61

Comparison of the Accuracy of Bracket Placement with Height Bracket Positioning Gauge and Boone Gauge  

PubMed Central

Background and aims Diverse gauges have been used to measure and determine bracket height for correct bracket positioning. The aim of the present study was to determine and compare bracket positioning accuracy by using height bracket positioning gauge (HBPG) and Boone gauge (BG). Materials and methods Nineteen sets of stone models were prepared from one patient. One set was employed to de-termine the ideal position of brackets, and the remaining nine pairs of sets for bracket placement by nine clinicians usingHBPG and BG. Teeth were then sectioned from the stone models and placed inside acrylic molds; photographs were takenand imported to a computer. In two groups, the position of each bonded bracket was compared in three aspects of vertical, mesiodistal and angular with the ideal position of every bracket. Finally, bracket positioning errors were measured. Results Mann-Whitney U test demonstrated significant differences in the means ofvertical error between the HBPG group and BG groups (P<0.001), while there were no significant differences between mesiodistal and angular errors. Facto-rial ANOVA revealed that gauge and tooth type, and the position of tooth on the right and left side of the mouth play a ma-jor role in the rate of vertical error. Conclusion Vertical accuracy of bracket positioning by the use of HBPG is more than that by BG. However, there is no difference between two gauges in relation to the mesiodistal and angular errors.

Mohammadi, Amir; Moslemzadeh, Seyed Hossein

2011-01-01

62

Sample-Based Surface Coloring  

Microsoft Academic Search

In this paper, we present a sample-based approach for surface coloring, which is independent of the original surface resolution and representation. To achieve this, we introduce the Orthogonal Fragment Buffer (OFB)-an extension of the Layered Depth Cube-as a high-resolution view-independent surface representation. The OFB is a data structure that stores surface samples at a nearly uniform distribution over the surface,

Kai Bürger; Jens Krüger; Rüdiger Westermann

2010-01-01

63

Shear Bond Strength of Orthodontic Brackets and Disinclusion Buttons: Effect of Water and Saliva Contamination  

PubMed Central

Purpose. The aim of this study was to assess the effect of water and saliva contamination on the shear bond strength and failure site of orthodontic brackets and lingual buttons. Materials and Methods. 120 bovine permanent mandibular incisors were randomly divided into 6 groups of 20 specimens each. Both orthodontic brackets and disinclusion buttons were tested under three different enamel surface conditions: (a) dry, (b) water contamination, and (c) saliva contamination. Brackets and buttons were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bond strength values and adhesive failure rate were recorded. Statistical analysis was performed using ANOVA and Tukey tests (strength values) and Chi squared test (ARI Scores). Results. Noncontaminated enamel surfaces showed the highest bond strengths for both brackets and buttons. Under water and saliva contamination orthodontic brackets groups showed significantly lower shear strengths than disinclusion buttons groups. Significant differences in debond locations were found among the groups under the various enamel surface conditions. Conclusions. Water and saliva contamination of enamel during the bonding procedure lowers bond strength values, more with orthodontic brackets than with disinclusion buttons.

Sfondrini, Maria Francesca; Fraticelli, Danilo; Gandini, Paola

2013-01-01

64

Heat Exchanger Support Bracket Design Calculations  

SciTech Connect

This engineering note documents the design of the heat exchanger support brackets. The heat exchanger is roughly 40 feet long, 22 inches in diameter and weighs 6750 pounds. It will be mounted on two identical support brackets that are anchored to a concrete wall. The design calculations were done for one bracket supporting the full weight of the heat exchanger, rounded up to 6800 pounds. The design follows the American Institute of Steel Construction (AISC) Manual of steel construction, Eighth edition. All calculated stresses and loads on welds were below allowables.

Rucinski, Russ; /Fermilab

1995-01-12

65

Measurement and comparison of bracket transfer accuracy of five indirect bonding techniques.  

PubMed

ABSTRACT Objective: To measure and compare bracket transfer accuracy of five indirect bonding (IDB) techniques. Materials and Methods: Five IDB techniques were studied: double polyvinyl siloxane (double-PVS), double vacuum-form (double-VF), polyvinyl siloxane vacuum-form (PVS-VF), polyvinyl siloxane putty (PVS-putty), and single vacuum-form (single-VF). Brackets were bonded on 25 identical stone working models. IDB trays were fabricated over working models (n ?=? 5 per technique) to transfer brackets to another 25 identical stone patient models. The mesiodistal (M-D), occlusogingival (O-G), and faciolingual (F-L) positions of each bracket were measured on the working and patient models using digital photography (M-D, O-G) and calipers (F-L). Paired t-tests were used to compare bracket positions between working and patient models, and analysis of variance was used to compare bracket transfer accuracy among the five techniques. Results: Between the working and patient models, double-VF had the most teeth with significant differences (n ?=? 6) and PVS-VF the fewest (n ?=? 1; P < .05). With one exception, all significant differences were ?0.26 mm and most (65%) were ?0.13 mm. When the techniques were compared, bracket transfer accuracy was similar for double-PVS, PVS-putty, and PVS-VF, whereas double-VF and single-VF showed significantly less accuracy in the O-G direction. Conclusions: Although overall differences in bracket position were relatively small, silicone-based trays had consistently high accuracy in transferring brackets, whereas methods that exclusively used vacuum-formed trays were less consistent. PMID:24555689

Castilla, Ana E; Crowe, Jennifer J; Moses, J Ryan; Wang, Mansen; Ferracane, Jack L; Covell, David A

2014-07-01

66

Sample-Based Surface Coloring  

PubMed Central

In this paper, we present a sample-based approach for surface coloring, which is independent of the original surface resolution and representation. To achieve this, we introduce the Orthogonal Fragment Buffer (OFB)—an extension of the Layered Depth Cube—as a high-resolution view-independent surface representation. The OFB is a data structure that stores surface samples at a nearly uniform distribution over the surface, and it is specifically designed to support efficient random read/write access to these samples. The data access operations have a complexity that is logarithmic in the depth complexity of the surface. Thus, compared to data access operations in tree data structures like octrees, data-dependent memory access patterns are greatly reduced. Due to the particular sampling strategy that is employed to generate an OFB, it also maintains sample coherence, and thus, exhibits very good spatial access locality. Therefore, OFB-based surface coloring performs significantly faster than sample-based approaches using tree structures. In addition, since in an OFB, the surface samples are internally stored in uniform 2D grids, OFB-based surface coloring can efficiently be realized on the GPU to enable interactive coloring of high-resolution surfaces. On the OFB, we introduce novel algorithms for color painting using volumetric and surface-aligned brushes, and we present new approaches for particle-based color advection along surfaces in real time. Due to the intermediate surface representation we choose, our method can be used to color polygonal surfaces as well as any other type of surface that can be sampled.

Burger, Kai; Kruger, Jens; Westermann, Rudiger

2011-01-01

67

Inducing Multilingual POS Taggers and NP Bracketers via Robust Projection Across Aligned Corpora  

Microsoft Academic Search

This paper investigates the potential for projecting linguistic annotations including part-of-speech tags and base noun phrase bracketings from one language to another via automatically word-aligned parallel corpora. First, experiments assess the accuracy of unmodified direct transfer of tags and brackets from the source language English to the target languages French and Chinese, both for noisy machine-aligned sentences and for clean

David Yarowsky; Grace Ngai

2001-01-01

68

An evaluation of slot size in orthodontic brackets--are standards as expected?  

PubMed

The slots of five upper left central incisor brackets from 11 commercially available bracket systems (3M Unitek, Monrovia, Calif: Twin Torque Roth, Clarity MBT, and Victory Series MBT; Dentarum, Pforzheim, Germany: Discovery Roth (0.56 mm) and Elegance Plastic Roth; Forestadent, Pforzheim, Germany: Mini Mono MBT; TP LaPorte, Indiana: Nu-Edge Roth and Mxi Advant-Edge Roth; Ormco Corp., Orange, Calif: Damon II SL Roth; Ortho Organizers, San Marcos, Calif: Elite Mini Opti-MIM Roth and Elite Mini Opti-MIM MBT) were measured in the 0.022-inch (0.5588 mm) dimension. Measurements were taken after operator calibration, and a digital readout was produced. Results indicate that all bracket slots are oversized. Three bracket systems slots (Twin Torque, Clarity, and Mini Mono) were within 5% (+/-1.08, 1.655, 1.75) of their stated dimensions with essentially parallel slot walls. The Elegance Plastic slot was parallel sided but oversized by 12% (+/-1.15). The geometry of bracket slots was also variable. The Victory Series slot was slightly divergent with the top oversized by 6% (+/-1.035). The Nu-Edge slot was divergent and slot top oversized by 14% (+/-1.32). The Mxi Advant-Edge, Damon II SL, Elite Mini Opti-MIM Roth, and MBT were all convergent, and the base of the Damon slot was oversized by 17% (+/-1.79). The Discovery bracket was convergent, and the slot base was oversized by 24% (+/-1.255), which was the largest recorded variance. This bracket also had a 7% difference between the widths of the slot top and the base. Inaccurate machining of bracket slot dimensions and the use of undersized archwires may directly and adversely affect three-dimensional tooth positioning. PMID:15387021

Cash, A C; Good, S A; Curtis, R V; McDonald, F

2004-08-01

69

Disinclusion of unerupted teeth by mean of self-ligating brackets: Effect of blood contamination on shear bond strength  

PubMed Central

Objectives: The aim of this study was to assess the effect of blood contamination on the shear bond strength and failure site of three different orthodontic self-ligating brackets. Study Design: 240 bovine permanent mandibular incisors were randomly divided into 12 groups of 20 specimens each. Orthodontic self-ligating brackets were tested under four different enamel surface conditions: a) dry, b) blood contamination before priming, c) blood contamination after priming, d) blood contamination before and after priming. Brackets were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bond strength values and adhesive failure rate were recorded. Statistical analysis was performed using ANOVA and Tukey tests (strength values), and Chi squared test (ARI Scores). Results: Non-contaminated enamel surfaces showed highest bond strengths for all self ligating brackets. Under blood-contamination shear bond strengths lowered for all brackets tested. Groups contaminated before and after primer application showed the lowest shear bond strength. Significant differences in debond locations were found among the groups under the various enamel surface conditions. Conclusions: Blood contamination of enamel during the bonding procedure lowers bond strength values of self ligating brackets, expecially when contamination occur in different times of the bonding procedure. Key words:Disinclusion, self ligating brackets, blood, contamination, enamel, orthodontics, oral surgery.

Sfondrini, Maria F.; Gatti, Sara; Gandini, Paola

2013-01-01

70

Effects of fluoride release from orthodontic bonding materials on nanomechanical properties of the enamel around orthodontic brackets  

PubMed Central

Background: The aim of the present study is to evaluate the effects of a fluoride-releasing composite resin bonding material on reducing enamel demineralization underneath and around orthodontic brackets and compare that with a conventional adhesive system. Materials and Methods: Buccal surfaces of 10 intact extracted premolar teeth were divided into two parts with nail varnish and stainless steel brackets were randomly bonded by two resin composite systems: (Transbond XT) and (Transbond XT plus Color Change) (3M, Unitek, Monrovia, CA, USA) on two sides of the teeth and then samples were placed in a demineralization solution. It is claimed that the second system has the ability of fluoride release. Elastic modulus and hardness of enamel were measured with nanoindentation test in 6 depths in 1-36 ?m from the enamel surface and in 7 regions: Control (intact enamel surface), underneath the brackets and also 50 and 100 ?m from the brackets edge. These nanomechanical features were evaluated in different regions and depths using analysis of variance and paired t-test (P < 0.05). Results: Considerable difference can be seen in different depths and regions in terms of hardness and elastic modulus. The region under the bracket with fluoridated adhesive shows similar results with intact enamel, whereas these parameters in fluoride less side show a significant reduction (P < 0.05). Conclusion: Results show that use of resin composite bonding system with the ability of fluoride release for bracket bonding, may reduce demineralization of enamel around brackets during orthodontic treatment.

Raji, Seyed Hamid; Banimostafaee, Hamed; Hajizadeh, Fatemeh

2014-01-01

71

Surface stress-based biosensors.  

PubMed

Surface stress-based biosensors, as one kind of label-free biosensors, have attracted lots of attention in the process of information gathering and measurement for the biological, chemical and medical application with the development of technology and society. This kind of biosensors offers many advantages such as short response time (less than milliseconds) and a typical sensitivity at nanogram, picoliter, femtojoule and attomolar level. Furthermore, it simplifies sample preparation and testing procedures. In this work, progress made towards the use of surface stress-based biosensors for achieving better performance is critically reviewed, including our recent achievement, the optimally circular membrane-based biosensors and biosensor array. The further scientific and technological challenges in this field are also summarized. Critical remark and future steps towards the ultimate surface stress-based biosensors are addressed. PMID:23948243

Sang, Shengbo; Zhao, Yuan; Zhang, Wendong; Li, Pengwei; Hu, Jie; Li, Gang

2014-01-15

72

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Bracket adhesive resin and tooth conditioner. 872...872.3750 Bracket adhesive resin and tooth conditioner. ...Identification. A bracket adhesive resin and tooth conditioner is a...polymethylmethacrylate, intended to cement an orthodontic bracket to...

2010-04-01

73

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Bracket adhesive resin and tooth conditioner. 872...872.3750 Bracket adhesive resin and tooth conditioner. ...Identification. A bracket adhesive resin and tooth conditioner is a...polymethylmethacrylate, intended to cement an orthodontic bracket to...

2009-04-01

74

Effect of acetic NaF solution on the corrosion behavior of stainless steel orthodontic brackets.  

PubMed

This study assessed the effect of acetic NaF solutions on stainless steel orthodontic brackets. Acetic acid was added to a 0.1% NaF solution to make two solutions, one with pH 3.5 and the other with pH 6. For the two different stainless steel brackets (Tomy, Dentaurum) used in this study, they had a similar elemental composition--except with Mo (molybdenum) in the Tomy bracket. The brackets were then immersed in the prepared test solutions for three days and their responses evaluated. In terms of hydrofluoric acid (HF) concentration, the 0.1%/pH 3.5 solution showed a high HF concentration at 227 ppm, while that of 0.1%/pH 6 solution was very low at 7 ppm. In terms of color change and element release, only the Dentaurum brackets in 0.1%/pH 3.5 solution showed an appreciable color change (deltaE* = 4.0) and released a great amount of elements (Fe, Cr, Ni, Mn) after three days. Otherwise, regardless of pH value and product, only minor color change (deltaE* < 1.0) and negligible element release occurred. In terms of surface modification, no visible changes in surface morphology were observed in any product after immersion in test solutions. PMID:16916238

Jang, Hee-Song; Son, Woo-Sung; Park, Soo-Byung; Kim, Hyung-Il; Yong, Hoon Kwon

2006-06-01

75

Retrieval analysis of different orthodontic brackets: the applicability of electron microprobe techniques for determining material heterogeneities and corrosive potential  

PubMed Central

Objective The objective of this study was to investigate the applicability of micro-analytical methods with high spatial resolution to the characterization of the composition and corrosion behavior of two bracket systems. Material and methods The surfaces of six nickel-free brackets and six nickel-containing brackets were examined for signs of corrosion and qualitative surface analysis using an electron probe microanalyzer (EPMA), prior to bonding to patient's tooth surfaces and four months after clinical use. The surfaces were characterized qualitatively by secondary electron (SE) images and back scattered electron (BSE) images in both compositional and topographical mode. Qualitative and quantitative wavelength-dispersive analyses were performed for different elements, and by utilizing qualitative analysis the relative concentration of selected elements was mapped two-dimensionally. The absolute concentration of the elements was determined in specially prepared brackets by quantitative analysis using pure element standards for calibration and calculating correction-factors (ZAF). Results Clear differences were observed between the different bracket types. The nickel-containing stainless steel brackets consist of two separate pieces joined by a brazing alloy. Compositional analysis revealed two different alloy compositions, and reaction zones on both sides of the brazing alloy. The nickel-free bracket was a single piece with only slight variation in element concentration, but had a significantly rougher surface. After clinical use, no corrosive phenomena were detectable with the methods applied. Traces of intraoral wear at the contact areas between the bracket slot and the arch wire were verified. Conclusion Electron probe microanalysis is a valuable tool for the characterization of element distribution and quantitative analysis for corrosion studies.

HOLST, Alexandra Ioana; HOLST, Stefan; HIRSCHFELDER, Ursula; von SECKENDORFF, Volker

2012-01-01

76

Torque Deformation Characteristicsof Plastic Brackets: A Comparative Study  

Microsoft Academic Search

Aim: The purpose of this study was to compare the torque deformation characteristics of seven commercially available plastic brackets, both amongst each other and with stainless steel brackets. Material and Methods: Ten brackets each of (1) pure polycarbonate, (2) ceramic reinforced polycarbonate, (3) fiberglass reinforced polycarbonate, (4) ceramic reinforced polycarbonate with metal slot, (5) fiberglass reinforced polycarbonate with metal slot,

Reza Sadat-Khonsari; Azita Moshtaghy; Volker Schlegel; Bärbel Kahl-Nieke; Mathias Möller; Oskar Bauss

2004-01-01

77

Are the low-shrinking composites suitable for orthodontic bracket bonding?  

PubMed Central

Purpose: To evaluate the shear bond strength (SBS), adhesive remnant index (ARI), and microleakage of low-shrinking and conventional composites used as an orthodontic bracket bonding adhesive. Materials and Methods: A hundred twenty non-caries human premolars, extracted for orthodontic purposes, were used in this study. Sixty of them were separated into two groups. Brackets were bonded to the teeth in the test group with Silorane (3M-Espe) and control group with Transbond-XT (3M-Unitek). SBS values of these brackets were recorded in MPa using a universal testing machine. ARI scores were determined after the failure of brackets. The remaining 60 teeth were divided into two groups and microleakage was evaluated by the dye penetration method. Statistical analyses were performed by Wilcoxon, Pearson Chi-square, and Mann–Whitney U tests at P < 0.05 level. Results: The mean SBS for Transbond XT was significantly greater than low-shrinking composite (P < 0.001). Significant differences (?2 =29.60, P < 0.001) were present between the two groups for the ARI scores. Microleakage values were lower in low-shrinking composite than in the control group, and this difference was found to be statistically significant (P < 0.001). Conclusions: Although low-shrinking composite produced insufficient SBS and ARI scores, microleakage values were lower in low-shrinking composite than in the control group on the etched enamel surfaces, when used as a bracket bonding composite.

Buyuk, Suleyman Kutalmis; Cantekin, Kenan; Demirbuga, Sezer; Ozturk, Mehmet Ali

2013-01-01

78

A method for producing controlled fluoride release from an orthodontic bracket.  

PubMed

The aim of this study was to manufacture and test, in vitro, a novel modification to provide fluoride-releasing orthodontic brackets. Thirty-two orthodontic brackets were drilled to produce a recess (approximately 1.3 mm in diameter and 0.7 mm in depth) at the centre of the bracket base. Four materials, with and without the addition of sodium fluoride, a glass ionomer cement (Ketac Cem micro), a resin-modified glass ionomer cement (RMGIC; GC Fuji Ortho LC), a zinc phosphate (Zinc Cement Improved), and a resin (Transbond XT) were used to fill the recess in the bracket base. Fluoride release was measured daily during the first week and then weekly for 10 weeks. An ion chromatograph with suppressed conductivity was used for free fluoride ion determination. Statistical analysis to determine the amount of flouride release was undertaken using analysis of variance and Tukey's test. During the first 2 weeks, the resin group, with the addition of 38 per cent sodium fluoride added, released significantly more free fluoride (P < 0.05), but after 2 weeks the fluoride release markedly decreased. After 5 weeks, the RMGIC group, with 15 per cent added sodium fluoride, had significantly higher (P < 0.05) daily fluoride release than the other groups. The findings demonstrated that an appropriate fluoridated material can be used as a fluoride-releasing reservoir in a modified orthodontic bracket to enable it to release fluoride over the period of fixed appliance treatment. PMID:17804428

Li, Song; Hobson, Ross S; Bai, Yuxing; Yan, Zhuoqun; Carrick, Thomas E; McCabe, John F

2007-12-01

79

A comparative study of lingual bracket bond strength.  

PubMed

Aim: To compare the adhesive potential, the mechanics implicated in adhesive failure, and the effect on the enamel of four brands of lingual brackets. Methods: One hundred sixty premolars and four types of commercially available lingual brackets (STB, ORG, Magic, and Stealth) were selected. Forty brackets per manufacturer were used, half bonded directly and half indirectly. Each of these bonding groups was further subdivided: 10 brackets were bonded without treatment, while the other 10 were sandblasted. Thus, a total of four groups were created for each type of bracket: (a) sandblasted and directly bonded, (b) sandblasted and indirectly bonded, (c) not sandblasted and directly bonded, and (d) not sandblasted and indirectly bonded. Immediately after bonding, each bracket was tested for adhesion strength, and each appliance was then examined via electron microscopy to calculate the ARI. Results: Statistical analysis showed a significant difference among the four bracket types; a general improvement in lingual appliance mechanical features provoked by sandblasting, albeit with some exceptions; and no significant effect of bonding method on the degree of bond strength. The ARI revealed that the most common area of adhesion crisis was at the adhesive-bracket interface. Conclusion: Overall, STB brackets performed better, and sandblasting proved to be an efficient way of improving the mechanical features of lingual brackets. Bonding technique, on the other hand, did not seem to exert a great influence on bonding success, and the bracket-adhesive interface was identified as the area most prone to failure. PMID:22022688

Lombardo, Luca; Kaplan, Andrea; Lapenta, Roberto; Bratti, Elena; Pera, Claudia; Scuzzo, Giuseppe; Siciliani, Giuseppe

2011-01-01

80

Effect of an acidic primer on shear bond strength of orthodontic brackets  

Microsoft Academic Search

A unique characteristic of some new etching systems is that they combine the conditioning and priming agents into a single acidic primer solution. The purpose of this study was to determine the effects on the shear bond strength and the bracket\\/adhesive failure mode when an acidic primer and other enamel etchants were used to condition the enamel surface before bonding.

Samir E. Bishara; Valeria V. Gordan; Leigh VonWald; Marc E. Olson

1998-01-01

81

Effects of Fluorosis and Bleaching on Shear Bond Strengths of Orthodontic Brackets  

PubMed Central

Objectives To evaluate the effects of fluorosis and bleaching on shear bond strengths of orthodontic brackets. Methods A total of 45 (30 fluorosed and 15 non-fluorosed) non-carious freshly extracted human permanent premolar teeth which were extracted for orthodontic reasons and without any caries or visible defects were used in this study. Fluorosed teeth were selected according to the modified Thylstrup and Fejerskov index (TFI), which is based on the clinical changes in fluorosed teeth. First group consisted of 15 fluorosed teeth. Second group of fluorosed teeth were bleached with a 35% hydrogen peroxide office bleaching agent. Third group served as control. No bleaching procedure was applied. Orthodontic brackets were bonded with a light cure composite resin and cured with a halogen light. After bonding, shear bond strengths of the brackets were tested with Universal testing machine. Results The results showed that fluorosis only and bleaching of fluorosed teeth significantly reduced the bond strengths of the orthodontic brackets (P < .001). Although bleaching of fluorosed teeth decreased the values more, no statistically significant difference was found between fluorosis group and fluorosis+bleaching group (P > .05). Conclusions Fluorosis and bleaching of fluorosed teeth reduce bracket bond strength to enamel, but the bond strength with these still exceed the minimum 6 to 8 MPa required to expect adequate clinical performance.

Adanir, Necdet; Turkkahraman, Hakan; Gungor, Ahmet Yalc?n

2007-01-01

82

Effect of bracket bonding with Er: YAG laser on nanomechanical properties of enamel  

PubMed Central

Background: The aim of this study was to compare the effects of conventional acid etching and laser etching on the nano-mechanical properties of the dental enamel using nano-indentation test. Materials and Methods: In this experimental in vitro study, buccal surfaces of 10 premolars were divided into three regions. One of the regions was etched with 37% phosphoric acid and another etched with Er:YAG laser, the third region was not etched. The brackets were bonded to both of etched regions. After thermocycling for 500 cycles, the brackets were removed and the teeth were decoronated from the bracket bonding area. Seven nano-indentations were applied at 1-31 ?m depth from the enamel surface in each region. Mean values of the hardness and elastic modulus were analyzed with repeated measures analysis of variance and Tukey HSD tests, using the SPSS software (SPSS Inc., version16.0, Chicago, Il, USA). P < 0.05 was considered as significant. Results: The hardness up to 21 ?m in depth and elastic modulus up to 6 ?m in depth from the enamel surface for laser-etched enamel had significantly higher values than control enamel and the hardness up to 11 ?m in depth and elastic modulus up to 6 ?m in depth for acid-etched enamel had significantly lower values than the control enamel. Conclusion: The mechanical properties of the enamel were decreased after bracket bonding with conventional acid etching and increased after bonding with Er:YAG laser.

Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh; Banimostafaee, Hamed

2014-01-01

83

A comparative evaluation of casein phosphopeptide-amorphous calcium phosphate and fluoride on the shear bond strength of orthodontic brackets.  

PubMed

The purpose of the study was to evaluate and compare the effects of topical application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride on the shear bond strength (SBS) of orthodontic brackets bonded to human premolar teeth. Eighty extracted human premolar teeth were cleansed of soft tissue, then polished with non-fluoridated pumice, and immersed in water for 1-3 months until testing. The teeth were randomly divided into four groups: group 1, control, without pre-treatment of the enamel; group 2, the enamel was treated with 5 per cent sodium fluoride varnish for 4 minutes; group 3, the enamel was treated with CPP-ACP for 3 minutes; and group 4, the enamel was treated with 5 per cent sodium fluoride and CPP-ACP. All bonded specimens were immersed in distilled water at room temperature for 24 hours and subsequently tested for SBS in a universal testing machine. After debonding, the bracket bases and the enamel surfaces were examined by eye to assess any adhesive remaining, in accordance with the Adhesive Remnant Index (ARI). Descriptive statistics were calculated for each group. Analysis of variance and Tukey honestly significant difference (HSD) test were performed to compare the SBS of the groups. The chi-square test was used to evaluate differences in ARI scores between the groups. The SBS in group 2 was significantly lower than groups 1, 3, and 4 (P < 0.001). ARI scores were not significantly different between the four groups (P > 0.05). CPP-ACP, either alone or combined with fluoride, may safely be used as a prophylactic agent before bracket bonding. PMID:20651043

Tabrizi, Anis; Cakirer, Banu

2011-06-01

84

Effect of fluoride solutions on the shear bond strength of orthodontic brackets.  

PubMed

The aim of this in vitro study was to evaluate the shear bond strength of brackets after pre-treatment with different fluoride solutions. This study used 48 freshly extracted sound bovine incisors that were randomly assigned to 4 experimental groups (n=12). CG: (control) without treatment; NF: 4 min application of neutral fluoride; APF: application of 1.23% acidulated phosphate fluoride (APF) for 4 min; and SFV: application of 5% sodium fluoride varnish for 6 h. For each group, after surface treatment, prophylaxis of enamel and bracket bonding with Transbond XT composite resin (3M) were performed following the manufacturer's specifications. The shear bond strength was performed with a universal testing machine 24 h after fixing the brackets. The tooth surfaces were analyzed to verify the adhesive remnant index (ARI). Data were analyzed statistically by ANOVA and Tukey's test (?=0.05). There was statistically significant difference among the groups (p<0.0001). CG and NF groups presented significantly higher bond strength than APF and SFV. There was no significant difference between CG and NF or between APF and SFV (p>0.05). The analysis of ARI scores revealed that most failures occurred at the enamel-resin interface. It may be concluded that the pre-treatment of enamel with 1.23% APF and 5% SFV prior to fixing orthodontic brackets reduces shear bond strength values. PMID:23338263

Leódido, Gabriela da Rocha; Fernandes, Hianna Oliveira; Tonetto, Mateus Rodrigues; Presoto, Cristina Dupim; Bandéca, Matheus Coêlho; Firoozmand, Leily Macedo

2012-01-01

85

The Poisson bracket on free null initial data for gravity.  

PubMed

Free initial data for general relativity on a pair of intersecting null hypersurfaces are well known, but the lack of Poisson brackets and concerns about caustics have stymied the development of a constraint free canonical theory. Here it is pointed out how caustics and generator crossings can be neatly avoided and Poisson brackets on free data are given. On sufficiently regular functions of the solution spacetime geometry these brackets match the Poisson brackets defined on such functions by the Hilbert action via Peierls' prescription. The symplectic 2-form is also given in terms of free data. PMID:19113400

Reisenberger, Michael P

2008-11-21

86

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Bracket adhesive resin and tooth conditioner. 872.3750...Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2011-04-01

87

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

...2014-04-01 false Bracket adhesive resin and tooth conditioner. 872.3750...Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2014-04-01

88

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Bracket adhesive resin and tooth conditioner. 872.3750...Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2013-04-01

89

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2010 CFR

... false Bracket adhesive resin and tooth conditioner. 872.3750 Section...872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a device composed...

2012-04-01

90

RSRM nozzle actuator bracket/lug fracture mechanics qualification test  

NASA Technical Reports Server (NTRS)

This is the final report for the actuator bracket/lug fracture mechanics qualification test. The test plan (CTP-0071) outlined a two-phase test program designed to answer questions about the fracture criticality of the redesigned solid rocket motor (RSRM) nozzle actuator bracket. An analysis conducted using the NASA/FLAGRO fracture mechanics computer program indicated that the actuator bracket might be a fracture critical component. In the NASA/FLAGRO analysis, a simple lug model was used to represent the actuator bracket. It was calculated that the bracket would fracture if subjected to an actuator stall load in the presence of a 0.10 in. corner crack at the actuator attachment hole. The 0.10 in. crack size corresponds to the nondestructive inspection detectability limit for the actuator bracket. The inspection method used is the dye penetrant method. The actuator stall load (103,424 lb) is the maximum load which the actuator bracket is required to withstand during motor operation. This testing was designed to establish the accuracy of the analytical model and to directly determine whether the actuator bracket is capable of meeting fracture mechanics safe-life requirements.

Kelley, Peggy

1993-01-01

91

Dynamic frictional behaviour of orthodontic archwires and brackets.  

PubMed

The aim of this study was to evaluate the frictional behaviour of 15 different archwires and 16 different brackets using small oscillating displacements when opposed to a standard stainless steel bracket or a standard stainless steel wire. Tests were run according to a pilot study at a frequency of 1 Hz and with a reciprocating tangential displacement of 200 microm, while the wire remained centred in the bracket slot under a load of 2 N. The results indicated a significant difference between the evaluated wires and brackets. The mean coefficient of friction (COF) of the wires varied from 0.16 for Imagination NiTi tooth-coloured wire to 0.69 for the True Chrome Resilient Purple wire, while for the brackets it ranged from 0.39 for Ultratrimm to 0.72 for the Master Series. The fact that in this study, a large number of different commercially available archwires and brackets were evaluated with the same apparatus according to the same protocol, allows a direct comparison of the different archwire and bracket combinations, and can assist in the choice of the optimal bracket-wire combination with regard to friction. PMID:15130039

Clocheret, K; Willems, G; Carels, C; Celis, J P

2004-04-01

92

Electrothermal debonding of ceramic brackets. An in vitro study.  

PubMed

Two different kinds of devices for electrothermal debonding of ceramic brackets are evaluated. Thirty human premolars were bonded with two types of ceramic brackets. Both devices were tested for electrothermal removal of the two bracket types. The pulpal wall temperature increase during electrothermal debonding was recorded in vitro under various circumstances. After debonding, the fracture site was located. The data were compared to the temperature rise after simulated exposure of the teeth to warm beverages. Irreversible pulp damage due to electrothermal debonding of ceramic brackets with both instruments is not to be expected because the obtained results stayed below established primate threshold temperatures and significantly below that of the stimulated control groups. A significant difference was noted when air cooling was initiated during electrothermal debonding. Fracture site location was significantly different in the two ceramic bracket types after electrothermal debonding. PMID:8500537

Brouns, E M; Schopf, P M; Kocjancic, B

1993-04-01

93

Effect of a Metal Primer on the Adhesive Interface between Composite and Lingual Brackets.  

PubMed

Aim: To test the null hypothesis was that there is no difference in the shear strength of indirectly bonded lingual brackets with or without prior application of metal primer on their bases. Materials and methods: Forty recently extracted human premolars were obtained and randomly divided into two groups of 20 each: group I (control), phosphoric acid and indirect bonding with Maximum Cure (Reliance Orthodontic Products, Itasca, IL, USA); and group II, application of metal primer (Metal Primer, Reliance Orthodontic Products) on bracket base prior to conditioning and indirect bonding. All products were used according to the manufacturer's instructions. A universal testing machine was used to apply a shear force directly onto the enamel- bracket interface at a speed of 1.0 mm/min. Results: Mean (SD) shear bond strength for group I was 12.87 (5.75) MPa and for the group II was 18.47 (8.48) MPa. The Student's t-test showed a signifcant difference (p = 0.0311) between the groups. The chi-square test for the adhesive remnant index (ARI) indicated that there was a signifcant difference (p = 0.2750). Conclusion: The application of metal primer increased the adhesion of lingual brackets, and may be a promising procedure for clinical orthodontics. Keywords: Temporomandibular joint dysfunction, Prevalence, edentulous, North Gujarat, Clicking sounds, Masseter. How to cite this article: e Cal Neto JP, de Albuquerque Calasans-Maia J, de Almeida NV, Rohen H, Freire MAG. Effect of a Metal Primer on the Adhesive Interface Between Composite and Lingual Brackets. J Contemp Dent Pract 2013;14(6):1106- 1108. Source of support: Nil Confict of interest: None declared. PMID:24858759

Neto, Julio Pedra E Cal; Calasans-Maia, José de Albuquerque; Almeida, Natalia Valli de; Rohen, Helen; Freire, Maria Angélica Galvão

2013-01-01

94

Bracketing--practical considerations in Husserlian phenomenological research.  

PubMed

Nursing research leans heavily towards naturalism, with phenomenology commonly adopted. The three main schools of phenomenology used are Husserl's descriptive approach, Heidegger's interpretive hermeneutic approach and the Dutch Utrecht School of phenomenology which combines characteristics of both. Husserl's approach--the description of ordinary human experiences as perceived by each individual--involves four main steps: bracketing, intuiting, analysing and describing. Many phenomenological nurse researchers consciously decide to adopt a Heideggerian approach because of the perceived difficulties in achieving bracketing. This paper examines the concept of bracketing (epoché) and outlines some of the practical considerations when attempting to achieve it. PMID:20222275

Hamill, Conal

2010-01-01

95

Effect of silica coating on bond strength between a gold alloy and metal bracket bonded with chemically cured resin  

PubMed Central

Objective The purpose of this study was to evaluate the effects of three different surface conditioning methods on the shear bond strength (SBS) of metal brackets bonded directly to gold alloy with chemically cured resin. Methods Two hundred ten type III gold alloy specimens were randomly divided into six groups according to the combination of three different surface conditioning methods (aluminum oxide sandblasting only, application of a metal primer after aluminum oxide sandblasting, silica coating and silanation) and thermocycling (with thermocycling, without thermocycling). After performing surface conditioning of specimens in accordance with each experimental condition, metal brackets were bonded to all specimens using a chemically cured resin. The SBS was measured at the moment of bracket debonding, and the resin remnants on the specimen surface were evaluated using the adhesive remnant index. Results Application of metal primer after aluminum oxide sandblasting yielded a higher bond strength than that with aluminum oxide sandblasting alone (p < 0.001), and silica coating and silanation yielded a higher bond strength than that with metal primer after aluminum oxide sandblasting (p < 0.001). There was no significant change in SBS after thermocycling in all groups. Conclusions With silica coating and silanation, clinically satisfactory bond strength can be attained when metal brackets are directly bonded to gold alloys using a chemically cured resin.

Ryu, Min-Ju; Lim, Sung-Hoon

2014-01-01

96

Automated classification of articular cartilage surfaces based on surface texture.  

PubMed

In this study the automated classification system previously developed by the authors was used to classify articular cartilage surfaces with different degrees of wear. This automated system classifies surfaces based on their texture. Plug samples of sheep cartilage (pins) were run on stainless steel discs under various conditions using a pin-on-disc tribometer. Testing conditions were specifically designed to produce different severities of cartilage damage due to wear. Environmental scanning electron microscope (SEM) (ESEM) images of cartilage surfaces, that formed a database for pattern recognition analysis, were acquired. The ESEM images of cartilage were divided into five groups (classes), each class representing different wear conditions or wear severity. Each class was first examined and assessed visually. Next, the automated classification system (pattern recognition) was applied to all classes. The results of the automated surface texture classification were compared to those based on visual assessment of surface morphology. It was shown that the texture-based automated classification system was an efficient and accurate method of distinguishing between various cartilage surfaces generated under different wear conditions. It appears that the texture-based classification method has potential to become a useful tool in medical diagnostics. PMID:17236517

Stachowiak, G P; Stachowiak, G W; Podsiadlo, P

2006-11-01

97

Evaluation of the effects of CO2 laser on debonding of orthodontics porcelain brackets vs. the conventional method.  

PubMed

Debonding of ceramic brackets due to their high bond strength and low fracture toughness is one of the clinician's complications. The purpose of this study is to evaluate the effect of a laser on shear bond strength, site of debonding, and ARI index during debonding of ceramic brackets and then compare it to the conventional method used for this procedure. Thirty polycrystalline alumina (G & H Series, Germany) brackets were bonded to 30 intact extracted first and second maxillary premolars and stored in a 1% thymol solution. A chemically cured orthodontic composite resin (No-mix, Unitek, USA) was used for bonding the brackets to the enamel surface on all teeth. All brackets were positioned 4 mm from the incisal edge of the teeth with an orthodontic bracket-positioning device. Then the teeth with bonded brackets were embedded in auto-polymerized polymethylmethacrylate (2.2.3 cm) blocks using a special device to make their slots horizontally parallel. These 30 teeth were then divided into two subgroups: control or no-lased (n = 15) and super pulse CO(2) laser (n = 15). To characterize the peak of SBS in two groups, we used an Instron machine while its blade was moving at a constant speed of 1 mm/min. For evaluating the site of debonding and the adhesive remnant index (ARI index), a light microscope and the Photoshop program were used. Means and standard deviations of the SBS in two subgroups shows that in the control group, the teeth have definitely higher values in comparison to the experimental group. The results of the two groups drew no substantial differences with respect to the surface of debonding, which was mostly within the adhesive. However, observing the results of ARI presented a significant distinction between the control and experimental group. This index denoted that the debonding site in the control group was closer to the enamel adhesive interface and, consequently, the rate of enamel damage in this group would be greater. The present study shows that a CO(2) laser has the potential to replace the conventional method for debonding ceramic brackets due to less debonding force and more adhesive remnant index on the tooth surface. PMID:20725757

Tehranchi, Azita; Fekrazad, Reza; Zafar, Morvarid; Eslami, Behnam; Kalhori, Katayoun A M; Gutknecht, Norbert

2011-09-01

98

Enamel resistance to demineralization following Er:YAG laser etching for bonding orthodontic brackets  

PubMed Central

Background: Several studies have shown that laser-etching of enamel for bonding orthodontic brackets could be an appropriate alternative for acid conditioning, since a potential advantage of laser could or might be caries prevention. This study compared enamel resistance to demineralization following etching with acid phosphoric or Er:YAG laser for bonding orthodontic brackets. Materials and Methods: Fifty sound human premolars were divided into two equal groups. In the first group, enamel was etched with 37% phosphoric acid for 15 seconds. In the second group, Er:YAG laser (wavelength, 2 940 nm; 300 mJ/pulse, 10 pulses per second, 10 seconds) was used for tooth conditioning. The teeth were subjected to 4-day PH-cycling process to induce caries-like lesions. The teeth were then sectioned and the surface area of the lesion was calculated in each microphotographs and expressed in pixel. The total surface of each specimen was 196 608 pixels. Results: Mean lesion areas were 7 171 and 7532 pixels for Laser-etched and Acid-etched groups, respectively. The two sample t-test showed that there was no significant difference in lesion area between the two groups (P = 0.914). Conclusion: Although Er:YAG laser seems promising for etching enamel before bonding orthodontic brackets, it does not reduce enamel demineralization when exposed to acid challenge.

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

2012-01-01

99

24. PHOTOGRAPH OF FIRST FLOOR. NOTE BRACKETS ON CENTER COLUMN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. PHOTOGRAPH OF FIRST FLOOR. NOTE BRACKETS ON CENTER COLUMN WHERE BRASS STATUS GAGES WERE MOUNTED TO MONITOR STEAM AND WATER PRESSURES IN YARD MAINS. SEE PHOTO CA-2294-25. - Mare Island Naval Shipyard, Firehouse, Vallejo, Solano County, CA

100

Analysis of Bracket Assembly for Portable Leak Detector Station  

SciTech Connect

This Supporting Document Presents Structural and Stress Analysis of a Portable Leak Detector Station for Tank Farms. The results show that the bracket assembly meets the requirements for dead load and natural phenomena hazards loads (seismic and wind).

ZIADA, H.H.

1999-08-19

101

20. DETAIL OF GAS FIXTURE (CALLED 'CALLA LILY BRACKET'), MANUFACTURED ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. DETAIL OF GAS FIXTURE (CALLED 'CALLA LILY BRACKET'), MANUFACTURED CIRCA 1855, SOUTH WALL OF SOUTHWEST ROOM, FIRST FLOOR - Ronald-Brennan House, 631 South Fifth Street, Louisville, Jefferson County, KY

102

Detail of castiron bracket supporting overhang on Train Shed. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of cast-iron bracket supporting overhang on Train Shed. - Central of Georgia Railway, Passenger Station & Train Shed, Corner of Louisville (Railroad) Road & West Broad Street, Savannah, Chatham County, GA

103

Detail of large, brick columns and bracket inside Electrical Shop ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of large, brick columns and bracket inside Electrical Shop - Central of Georgia Railway, Savannah Repair Shops & Terminal Facilities, Electrical Shop, Bounded by West Broad, Jones, West Boundary & Hull Streets, Savannah, Chatham County, GA

104

Surface-based inversions above central Greenland  

NASA Astrophysics Data System (ADS)

Surface-based temperature inversions (SBIs) are studied at Summit Station in central Greenland during the period spanning July 2010 to May 2012. The frequency and intensity of SBI are examined using microwave radiometer (MWR) temperature retrievals, radiosonde profiles, and near-surface meteorological data. Using the MWRs' high temporal resolution, the diurnal, monthly, and annual cycles are investigated. Monthly mean values in SBI occurrence and intensity show that surface-based inversions are prevalent in the winter with decreasing values in the summer months. A case study on 20 February 2011 suggests that factors other than solar elevation angle influence the intensity of surface-based inversions. An increase in liquid water path corresponds to a decrease in SBI intensity, suggesting that liquid-bearing clouds, especially within the lowest 1 km, are associated with weaker surface-based inversions.

Miller, N. B.; Turner, D. D.; Bennartz, R.; Shupe, M. D.; Kulie, M. S.; Cadeddu, M. P.; Walden, Von P.

2013-01-01

105

The Poisson bracket for q-deformed systems  

NASA Astrophysics Data System (ADS)

It is shown that the quantum system of q-deformed oscillators with the Uq(n) group symmetry can be obtained by the canonical quantization of a classical system with a modified Poisson bracket. The modification of the Poisson bracket is connected with a non-canonical transformation of phase space variables. In this approach, the deformation parameter turns out to be a function of the Planck constant and some dimensional parameters characterizing the classical system.

Shabanov, S. V.

1992-11-01

106

Conventionally ligated versus self-ligating metal brackets--a comparative study  

Microsoft Academic Search

SUMMARY The purpose of this study was to compare the frictional properties of four self-ligating metal brackets, Speed, Damon 2, In-Ovation, and Time, with those of three conventionally ligated metal brackets, Time, Victory Twin, and Discovery. The self-ligating Time bracket can also be used as a conventionally ligated bracket. Friction was tested 20 times for each bracket\\/wire combination using a

C. A. Reicheneder; T. Gedrange; S. Berrisch; P. Proff; U. Baumert; A. Faltermeier; D. Muessig

2008-01-01

107

Devices based on surface plasmon interference filters  

NASA Technical Reports Server (NTRS)

Devices based on surface plasmon filters having at least one metal-dielectric interface to support surface plasmon waves. A multi-layer-coupled surface plasmon notch filter is provided to have more than two symmetric metal-dielectric interfaces coupled with one another to produce a transmission spectral window with desired spectral profile and bandwidth. Such notch filters can form various color filtering devices for color flat panel displays.

Wang, Yu (Inventor)

2001-01-01

108

Effect of etching time and light source on the bond strength of metallic brackets to ceramic.  

PubMed

This study evaluated the bond strength of brackets to ceramic testing different etching times and light sources for photo-activation of the bonding agent. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. After application of silane on the ceramic surface, metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek). The specimens for each etching time were assigned to 4 groups (n=15), according to the light source: XL2500 halogen light, UltraLume 5 LED, AccuCure 3000 argon laser, and Apollo 95E plasma arc. Light-activation was carried out with total exposure times of 40, 40, 20 and 12 s, respectively. Shear strength testing was carried out after 24 h. The adhesive remnant index (ARI) was evaluated under magnification. Data were subjected to two-way ANOVA and Tukey's test (?=0.05). Specimens etched for 20 s presented significantly lower bond strength (p<0.05) compared with those etched for 60 s. No significant differences (p>0.05) were detected among the light sources. The ARI showed a predominance of scores 0 in all groups, with an increase in scores 1, 2 and 3 for the 60 s time. In conclusion, only the etching time had significant influence on the bond strength of brackets to ceramic. PMID:21915523

Gonçalves, Paulo Roberto Amaral; Moraes, Rafael Ratto de; Costa, Ana Rosa; Correr, Américo Bortolazzo; Nouer, Paulo Roberto Aranha; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

2011-01-01

109

Clinical evaluation of the failure rate of metallic brackets bonded with orthodontic composites.  

PubMed

The purpose of the present study was to evaluate in vivo the failure rate of metallic brackets bonded with two orthodontic composites. Nineteen patients with ages ranging from 10.5 to 38.7 years needing corrective orthodontic treatment were selected for study. The enamel surfaces from second premolars to second premolars were treated with Transbond Plus-Self Etching Primer (3M Unitek). Next, 380 orthodontic brackets were bonded on maxillary and mandibular teeth, as follows: 190 with Transbond XT composite (3M Unitek) (control) and 190 with Transbond Plus Color Change (3M Unitek) (experimental) in contralateral quadrants. The bonded brackets were light cured for 40 s, and initial alignment archwires were inserted. Bond failure rates were recorded over a six-month period. At the end of the evaluation, six bond failures occurred, three for each composite. Kaplan-Meyer method and log-rank test (Mantel-Cox) was used for statistical analysis, and no statistically significant difference was found between the materials (p=0.999). Both Transbond XT and Transbond Plus Color Change composites had low debonding rates over the study period. PMID:23207856

Romano, Fábio Lourenço; Valério, Rodrigo Alexandre; Gomes-Silva, Jaciara Miranda; Ferreira, José Tarcísio Lima; Faria, Gisele; Borsatto, Maria Cristina

2012-01-01

110

Does the time interval after bleaching influence the adhesion of orthodontic brackets?  

PubMed Central

Objective To test the null hypothesis that no difference exists between the effects of at-home bleaching and in-office bleaching on shear bond strength (SBS) with bracket bonding at 4 different time intervals after dental bleaching. Methods Ninety extracted human premolars were randomly divided into 9 groups (n = 10) according to the bleaching methods used (at-home bleaching and in-office bleaching) and the storage time in artificial saliva (30 min, 1 day, 2 weeks, and 3 weeks before bonding). The control group was stored in artificial saliva for 7 days. Brackets were bonded with the Transbond XT adhesive system, and SBS testing was performed. The adhesive remnant index (ARI) was used to assess the amount of resin remaining on the enamel surfaces after debonding. The SBS data were analyzed by analysis of variance (ANOVA) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. Significance for all statistical tests was predetermined to be p < 0.05. Results The SBS of the unbleached group was significantly higher (p < 0.05) than that of the bleached groups (except for the group bonded 30 min after at-home bleaching). Conclusions The null hypothesis was not totally rejected. All bleaching groups tested had decreased SBS of the brackets to the enamel, except for the group bonded 30 min after at-home bleaching. The SBS returned to values close to those of the unbleached enamel within 3 weeks following bleaching.

Nascimento, Glaucia Cristina Rodrigues; de Miranda, Cyndi Albuquerque; Machado, Sissy Maria Mendes; Brandao, Gustavo Antonio Martins; de Almeida, Haroldo Amorim

2013-01-01

111

The effect of casein phosphopeptide amorphous calcium phosphate on the in vitro shear bond strength of orthodontic brackets  

PubMed Central

Objective The purpose of this study was to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on the shear bond strength (SBS) of brackets bonded to non-demineralized teeth with either phosphoric acid etching or self-etching primer. Methods Sixty human premolars were randomly assigned to 1 of 4 treatment groups (n = 15 each): phosphoric acid etching (group 1); self-etching primer (group 2); CPP-ACP for 2 weeks + phosphoric acid etching (group 3), and CPP-ACP for 2 weeks + self-etching primer (group 4). After bonding of the maxillary premolar metal brackets, specimens were subjected to shear forces in a testing machine. Scanning electron microscopy was used to observe etching patterns on the enamel surfaces of all teeth. A 2-way analysis of variance was used to test for effects of CPP-ACP and etching system on SBS. Results Significantly higher mean SBSs were observed in groups subjected to phosphoric acid etching (i.e., groups 1 and 3; p < 0.05). On the other hand, SBSs did not appear to be influenced by CPP-ACP (i.e., groups 3 and 4; p > 0.05). We observed a uniform and clear etched pattern on the enamel surface of the phosphoric acid etching groups. Conclusions CPP-ACP does not significantly affect the SBS of orthodontic brackets bonded to non-demineralized teeth, regardless of which adhesive method is used to bond the brackets.

Park, Sun-Youn; Cha, Jung-Yul; Kim, Kyoung-Nam

2013-01-01

112

Comparative analysis of slot dimension in lingual bracket systems  

PubMed Central

Background Orthodontic treatment with fixed appliances requires - among others - the correct clinical expression of torque, which depends on the precise fitting of archwire and slot. Especially in the lingual technique torque problems become clinically more evident than in labial appliances also with respect to the vertical alignment of teeth due to different distances from the center of resistance. The purpose of the present study was to compare the preciseness of slot dimensions of different lingual bracket systems. Methods Three lingual bracket systems were included in the study (7th Generation and STb, Ormco, Glendora, CA, USA; Incognito, TOP-Service/3 M Unitek, Monrovia, CA, USA). Non destructive analysis of vertical slot dimensions was performed using precision pin gauges (Azurea, Belprahon, Switzerland) that were tapered in increments of 0.002 mm (0.00008 inch). The sizes of 240 incisor and canine brackets were measured per system (total: 720). Data were compared using one-way ANOVA. A p-value < 0.05 was considered statistically significant. Results Average slot dimensions were 0.467 mm ± 0.007 mm (0.0184 inch ± 0.0003 inch) for the 7th Generation bracket system, 0.466 mm ± 0.004 mm (0.0183 inch ± 0.0001) inch for the STb bracket system and 0.459 mm ± 0.004 mm (0.0181 inch ± 0.0001) inch for the Incognito bracket system. Differences between systems were statistically significant (p < 0.05). Conclusions The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play. These aspects must be considered in lingual orthodontic treatment.

2009-01-01

113

The Shear Bond Strengths of Metal and Ceramic Brackets: An in-Vitro Comparative Study.  

PubMed

Aim: This study has compared the Shear Bond Strengths (SBSs) of ceramic brackets and metal brackets. Materials and Method: Forty freshly extracted, human maxillary first premolars were selected for bonding. They were equally bonded with ceramic brackets (Transcend series 6000) and metal brackets (Mini Dynalock Straight wire brackets). A no - mix orthodontic adhesive system was used. Their shear bond strengths were measured by using the Instron universal machine. Results: The mean bond strength of the ceramic brackets was 20.68 ± 3.89 Mpa and that of the metal brackets was 12.15 ± 1.32 MPa. Conclusion: The shear bond strength of the ceramic brackets was found to be superior than that of the metal brackets. PMID:23998105

Reddy, Y G; Sharma, Rohit; Singh, Ammandeep; Agrawal, Vishal; Agrawal, Vijay; Chaturvedi, Saurab

2013-07-01

114

The Shear Bond Strengths of Metal and Ceramic Brackets: An in-Vitro Comparative Study  

PubMed Central

Aim: This study has compared the Shear Bond Strengths (SBSs) of ceramic brackets and metal brackets. Materials and Method: Forty freshly extracted, human maxillary first premolars were selected for bonding. They were equally bonded with ceramic brackets (Transcend series 6000) and metal brackets (Mini Dynalock Straight wire brackets). A no – mix orthodontic adhesive system was used. Their shear bond strengths were measured by using the Instron universal machine. Results: The mean bond strength of the ceramic brackets was 20.68 ± 3.89 Mpa and that of the metal brackets was 12.15 ± 1.32 MPa. Conclusion: The shear bond strength of the ceramic brackets was found to be superior than that of the metal brackets.

Reddy, Y G; Sharma, Rohit; Singh, Ammandeep; Agrawal, Vishal; Agrawal, Vijay; Chaturvedi, Saurab

2013-01-01

115

Fracture strengths of ceramic brackets subjected to mesial-distal archwire tipping forces.  

PubMed

This study tested the strength of ceramic orthodontic brackets subjected to mesial-distal tipping forces on five types of preadjusted, maxillary right central incisor ceramic twin brackets for both 0.018" and 0.022" slot sizes. Description of each bracket was by manufacturer's abbreviation-crystallinity-slot bracket, eg., AL-P-18, meaning Allure-polycrystalline-0.018" slot bracket. Thirty brackets of each type were used for a total of 300 brackets, each bonded to a porcelain denture tooth. A special apparatus was designed to hold the denture tooth, the wire, and the bracket in a standard position while an Instron machine applied a tipping force to the full size rectangular archwire at a distance of 7.0 mm lateral to the center of the bracket. The tipping force was applied until the bracket fractured. The fracture force, fracture angle, and fracture location were recorded. High fracture force values tended to accompany large fracture angles while low fracture force values tended to be associated with small fracture angles. The clinical significance was that the stronger ceramic brackets can be expected to withstand larger amounts of archwire tipping adjustments prior to bracket fracture. With the literature indicating the optimum force for tipping of maxillary incisors to be from 50 to 125 g, all the brackets are sufficiently strong to consistently withstand the suggested magnitude of archwire tipping forces. However, if excessive tipping forces were required by the clinician, ceramic brackets would be prone to fracture. PMID:1554165

Rhodes, R K; Duncanson, M G; Nanda, R S; Currier, G F

1992-01-01

116

Helical surface reconstruction based on CMM  

NASA Astrophysics Data System (ADS)

The reconstruction of helical surface plays an important role in many engineering and scientific applications. This paper tends to establish an effective processing scheme of surface reconstruction of scatter 3D points, and make an in-depth exploration for the preprocessing technology of scatter points set and the algorithm of three-dimension model surface reconstruction. This paper has three main aspects: data acquisition, data preprocess and surface reconstruction. First, by comparing several measuring equipments, the screw parts are scanned via CMM (Coordinate Measuring Machine). Initial 3D point clouds are obtained by setting the scanning route according to the shape of the targets. Second, Using "3?" criteria point de-noising is applied to the initial data points. Then Heap Sort is used to sort these points, being convenient for saving data and reconstructing the surface. Third, this paper presents a surface reconstruction method based on triangulation algorithm. The triangular meshes are generated based on Delaunay triangulation technique in two dimensions. And Loop Subdivision is adopted in order to get manifold meshes. Finally the surface reconstruction of an involute worm and an Archimedes worm shows that this approach is feasible.

Pan, Zhikang; Zhu, Lianqing; Chen, Qingshan; Guo, Yangkuan

2010-12-01

117

Quantifying enamel demineralization from teeth with orthodontic brackets--a comparison of two methods. Part 1: repeatability and agreement.  

PubMed

The aim of this investigation was to compare the repeatability of measuring enamel demineralization surrounding an orthodontic bracket using two techniques: computerized image analysis from digitally converted photographic slides and quantitative light-induced fluorescence (QLF). Fifteen human molars were halved and shaped to look like incisors. The teeth were individually numbered and orthodontic brackets bonded to the buccal surface. The crowns were covered with acid resistant varnish, except for windows approximately 1.5 x 3 mm adjacent to the gingival, occlusal, mesial, and distal edges of the bracket. The windows were variously exposed to a demineralizing gel for 0, 3, 7, or 14 days, and the acid resistant varnish was removed. Standardized photographic slides and QLF images of the teeth were taken. These were repeated after 1 week. The slides were converted to grey scale digital format and analysed using Image-Pro Plus 3.0. The QLF images were stored, processed, and analysed using customized software. All images were recoded for blind analysis. The four surfaces of the bracket were inspected and only areas of suspected demineralization were analysed. This was repeated after 1 week. The limits of agreement and mean difference between repeat readings of the area of demineralization were similar for both techniques (-0.04 +/- 0.43 for photographs and -0.10 +/- 0.63 for QLF). Mean grey level (photographs) and mean loss of fluorescence from that area (deltaF) (QLF) showed acceptable limits of agreement. The Intra Class Correlation (ICC) was below 0.81 for the measurement of area from QLF, suggesting that random error needs to be reduced. There was evidence of systematic bias for the repeat readings of the grey levels from the photographs (P < 0.001). Enamel demineralization surrounding an orthodontic bracket can be measured reproducibly using these two techniques. PMID:12737213

Benson, Philip E; Pender, Neil; Higham, Susan M

2003-04-01

118

Bracketed morality revisited: how do athletes behave in two contexts?  

PubMed

The concept of bracketed morality has received empirical support in several sport studies (e.g., Bredemeier & Shields, 1986a, 1986b). However, these studies have focused on moral reasoning. In this research, we examined bracketed morality with respect to moral behavior in sport and university contexts, in two studies. Male and female participants (Study 1: N = 331; Study 2: N = 372) completed questionnaires assessing prosocial and antisocial behavior toward teammates and opponents in sport and toward other students at university. Study 2 participants also completed measures of moral disengagement and goal orientation in both contexts. In most cases, behavior in sport was highly correlated with behavior at university. In addition, participants reported higher prosocial behavior toward teammates and higher antisocial behavior toward opponents in sport than toward other students at university. The effects of context on antisocial behavior were partially mediated by moral disengagement and ego orientation. Our findings extend the bracketed morality concept to prosocial and antisocial behavior. PMID:24197713

Kavussanu, Maria; Boardley, Ian D; Sagar, Sam S; Ring, Christopher

2013-10-01

119

Galvanic corrosion behavior of orthodontic archwire alloys coupled to bracket alloys.  

PubMed

The purpose of this study was to provide a quantitative assessment of galvanic corrosion behavior of orthodontic archwire alloys coupled to orthodontic bracket alloys in 0.9% NaCl solution and to study the effect of surface area ratios. Two common bracket alloys, stainless steels and titanium, and four common wire alloys, nickel-titanium (NiTi) alloy, beta-titanium (beta-Ti) alloy, stainless steel, and cobalt-chromium-nickel alloy, were used. Three different area ratios, 1:1, 1:2.35, and 1:3.64, were used; two of them assumed that the multibracket appliances consists of 14 brackets and 0.016 inch of round archwire or 0.016 x 0.022 inch of rectangular archwire. The galvanic current was measured for 3 successive days using zero-impedance ammeter. When the NiTi alloy was coupled with Ti (1:1, 1:2.35, and 1:3.64 of the surface area ratio) or beta-Ti alloy was coupled with Ti (1:2.35 and 1:3.64 of the surface area ratio), Ti initially was the anode and corroded. However, the polarity reversed in 1 hour, resulting in corrosion of the NiTi or beta-Ti. The NiTi alloy coupled with SUS 304 or Ti exhibited a relatively large galvanic current density even after 72 hours. It is suggested that coupling SUS 304-NiTi and Ti-NiTi may remarkably accelerate the corrosion of NiTi alloy, which serves as the anode. The different anode-cathode area ratios used in this study had little effect on galvanic corrosion behavior. PMID:16808581

Iijima, Masahiro; Endo, Kazuhiko; Yuasa, Toshihiro; Ohno, Hiroki; Hayashi, Kazuo; Kakizaki, Mitsugi; Mizoguchi, Itaru

2006-07-01

120

Lie Bracket of Vector Fields in Noncommutative Geometry  

NASA Astrophysics Data System (ADS)

The aim of this paper is to avoid some difficulties, related with the Lie bracket, in the definition of vector fields in a noncommutative setting, as they were defined by Woronowicz, Schmüdgen-Schüler and Aschieri-Schupp. We extend the definition of vector fields to consider them as derivations of the algebra, through Cartan pairs introduced by Borowiec. Then, using translations, we introduce the invariant vector fields. Finally, the definition of Lie bracket realized by Dubois-Violette, considering elements in the center of the algebra, is also extended to these invariant vector fields.

Jara, P.; Llena, D.

2003-09-01

121

Surface modification of polypropylene based particle foams  

NASA Astrophysics Data System (ADS)

This paper deals with the modification of the surface properties of expanded polypropylene (EPP). EPP is a semi-hard to soft elastic thermoplastic foam. The characteristic surface of EPP shows process-related steam nozzle imprints and gussets. Therefore EPP does not satisfy the quality requirements for visible automotive applications. In order to meet these demands, plastic surfaces are usually enhanced with functional or decorative coatings, e.g. textiles, plastic films or paint. The coating of plastics with low surface energies such as PP often leads to adhesion problems by reason of the missing polar and functional groups. This paper gives an evaluation of activation and pre-treatment methods of EPP, with the aim to identify the most suitable pre-treatment method. For this purpose five typical surface treatment methods - flame treatment, corona, fluorination, atmospheric and low-pressure plasma - were performed on EPP samples. As a comparison criterion the maximum increase in the adhesion force between a polyurethane-based coating and the modified EPP substrate was selected. Moreover the influence of the selected pre-treatment method on the increase in the total surface energy and its polar component was investigated by the drop shape analysis method. The results showed that the contact angle measurement is a suitable method to determine the polar and disperse fractions of the surface tension of EPP. Furthermore, all performed methods increased the adhesion of EPP.

Schreier, P.; Trassl, C.; Altstädt, V.

2014-05-01

122

In-vitro evaluation of an experimental method for bonding of orthodontic brackets with self-adhesive resin cements  

PubMed Central

Background Self-adhesive resin cements do not require the surface treatment of teeth and are said to release fluoride, which makes them suitable candidates for bonding of orthodontic brackets. The objectives of this study was to investigate the shear bond strength (SBS) of self-adhesive resin cements on etched on non-etched surfaces in vitro and to assess their fluoride release features. Materials and Methods Four fluoride-releasing dual-cure self-adhesive resin cements were investigated. For SBS experiment, 135 freshly extracted human maxillary premolars were used and divided into nine groups of 15 teeth. In the control group, brackets were cemented by Transbond XT (3M Unitek, USA), in four groups self-adhesive resin cements were used without acid-etching and in four groups self-adhesive cements were applied on acid-etched surfaces and the brackets were then deboned in shear with a testing machine. Adhesive remnant index (ARI) scores were also calculated. For fluoride release investigation, 6 discs were prepared for each self-adhesive cement. Transbond XT and Fuji Ortho LC (GC, Japan) served as negative and positive control groups, respectively. The fluoride release of each disc into 5 ml of deionized water was measured at days 1, 2, 3, 7, 14, 28, and 56 using a fluoride ion-selective electrode connected to an ion analyzer. To prevent cumulative measurements, the storage solutions were changed daily. Results The SBS of brackets cemented with Transbond XT were significantly higher compared to self-adhesives applied on non-etched surfaces (P<0.001). However, when the self-adhesive resin cements were used with enamel etching, no significant differences was found in the SBS compared to Transbond XT, except for Breeze. The comparisons of the ARI scores indicated that bracket failure modes were significantly different between the etched and non-etched groups. All self-adhesive cements released clinically sufficient amounts of fluoride for an extended period of time. Conclusion For the tested cements, the strongest bonds were obtained by enamel acid-etching prior to bracket bonding. All the self-adhesive resin cements had significant long-term fluoride release and could be recommended as suitable fluoride-releasing orthodontic bonding materials.

Ramazanzadeh, Barat Ali; Merati, Mohsen; Shafaee, Hooman; Dogon, Leon; Sohrabi, Keyvan

2013-01-01

123

Local surface model-based deinterlacing algorithm  

NASA Astrophysics Data System (ADS)

We present an efficient deinterlacing method via mathematical modeling of the neighbor pixels in the local region. The local surface model is designed using the quadratic equation having two-dimensional coordinate variables. Unlike conventional deinterlacing methods, the proposed method avoids using directional difference measures, resulting in reduced limitation on the number of considering edge directions. By modeling the local surface, it is easier to derive the true characteristic of the local region in a natural image than utilizing the directional difference measure. In order to decide the optimal coefficients of the surface model, the neighbor pixels around the current pixel to be interpolated are utilized. Once the coefficients are determined, the surface model estimates the pixel intensity of the current pixel to be interpolated. Simulation results show that the proposed surface model-based deinterlacing method minimizes the interpolation error. Compared to the traditional deinterlacing methods and Wiener filter-based interpolation method, the proposed method improves the subjective quality of the interpolated edges while maintaining a higher peak signal-to-noise-ratio level.

Park, Sang-Jun; Jeong, Jechang

2011-01-01

124

A surface-based cloud observing system  

NASA Technical Reports Server (NTRS)

The paper describes a surface-based system, called the Cloud Observing System (COS), that was developed for measurements of the dynamical and thermodynamical properties of clouds and of their interaction with the large-scale environment, by combining several remote sensors and in situ systems. The atmospheric parameters that will be measured by COS include precipitation, the velocity and direction of wind, the cloud liquid water, the low-level winds and turbulence structure, integrated liquid and vapor quantities, the temperature and water profiles, the cloud radiance and the cloud base temperature, irradiances at the surface, the low-level temperature profile, the cloud-base height, and the cloud fraction; video cameras will provide visual records of clouds.

Albrecht, B. A.; Ackerman, T. P.; Thomson, D. W.; Mace, G.; Miller, M. A.; Peters, R. M.

1991-01-01

125

Image based modeling via plane sweep based surface growing  

Microsoft Academic Search

In this paper, we present a multi-view stereo based shaped modeling method. Using images captured from different viewpoints, our approach can provide objects' 3d models with high fidelity details automatically and efficiently. We firstly use a strict plane based sweep stereo method via GPU to compute quasi-dense depth maps which usually have many holes. Then, a simplified patch based surface

Bo Shu; Xianjie Qiu; Zhaoqi Wang

2009-01-01

126

Torque Capacity of Metal and Plastic Brackets with Reference to Materials, Application, Technology and Biomechanics  

Microsoft Academic Search

Aim: The aim of the present study was to investigate slot deformation and the equivalent torque capacity of plastic brackets in comparison with those of a metal bracket in vitro and to simulate them under clinical conditions. Material and Method: For this purpose the expansion characteristics of the brackets and their resistance to extraoral mechanical loading were compared in in-vitro

Henner Gmyrek; Christoph Bourauel; Gert Richter; Winfried Harzer

2002-01-01

127

Shear bond strength of self-ligating brackets.  

PubMed

The aim of this study was to compare the shear bond strength (SBS) and adhesive remnant index (ARI) scores of conventional and self-ligating brackets. Conventional stainless steel brackets (group 1, Step; Leone) and three different passive and interactive self-ligating brackets (group 2, Smart Clip, 3M Unitek; group 3, Quick, Forestadent; and group 4, Damon 3MX, Ormco) were tested. Four groups of 20 specimens each were bonded with an adhesive system (Ortho Solo primer, Ormco and Transbond XT resin, 3M Unitek) onto bovine enamel and subsequently tested using an Instron universal testing machine. SBS values and adhesive failure rate were recorded. Statistical analysis was performed with analysis of variance and Scheffé tests to determine bond strength values, whereas a chi-square test was used for ARI scores. Groups 2 and 4 showed significantly higher SBS values than the other two groups. Moreover, groups 1 and 3 showed a higher frequency of ARI score 1, whereas groups 2 and 4 showed higher frequency of ARI score 2. All the brackets demonstrated a clinically adequate SBS. PMID:20660129

Sfondrini, Maria Francesca; Gatti, Sara; Scribante, Andrea

2011-02-01

128

Analysis of Bracket Assembly for Diversion Box Leak Detector  

SciTech Connect

This Supporting Document Presents Structural and Stress Analysis of a Bracket Assembly for the diversion box leak detectors related to the Cross Site Transfer Project. The results show that the assembly meets the requirements for dead load and natural phenomena hazards loads (seismic and wind).

ZIADA, H.H.

1999-08-19

129

43. Detail view of pivoting bracket used to move heavy ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

43. Detail view of pivoting bracket used to move heavy iron plate that covered trough next to iron notch when No. 2 Furnace was tapped. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

130

An OSEE Based Portable Surface Contamination Monitor  

NASA Technical Reports Server (NTRS)

Many industrial and aerospace processes involving the joining of materials, require sufficient surface cleanliness to insure proper bonding. Processes as diverse as painting, welding, or the soldering of electronic circuits will be compromised if prior inspection and removal of surface contaminants is inadequate. As process requirements become more stringent and the number of different materials and identified contaminants increases, various instruments and techniques have been developed for improved inspection. One such technique based on the principle of Optically Stimulated Electron Emission (OSEE) has been explored for a number of years as a tool for surface contamination monitoring. Some of the benefits of OSEE are: it's non-contacting; requires little operator training; and has very high contamination sensitivity. This paper describes the development of a portable OSEE based surface contamination monitor. The instrument is suitable for both hand-held and robotic inspections with either manual or automated control of instrument operation. In addition, instrument output data is visually displayed to the operator and may be output to an external computer for archiving or analysis.

Perey, Daniel F.

1997-01-01

131

A surface-stress-based microcantilever aptasensor.  

PubMed

Biosensors based on microcantilevers convert biological recognition events into measurable mechanical displacements. They offer advantages such as small size, low sample volume, label-free detection, ease of integration, high-throughput analysis, and low development cost. The design and development of a microcantilever-based aptasensor employing SU-8 polymer as the fabrication material is presented in this paper. Aptamers are employed as bioreceptor elements because they exhibit superior specificity compared to antibodies due to their small size and physicochemical stability. To immobilise thrombin DNA aptamer on the bare SU-8 surface of the aptasensor, a combined plasma mode treatment method is implemented which modifies the surface of the aptasensor. Label-free detection of thrombin molecules using the fabricated aptasensor is successfully demonstrated. The measured deflection is one order of magnitude higher than that of a silicon nitride microcantilever biosensor. The developed aptasensor also demonstrates high specificity. PMID:24681916

Lim, Yang Choon; Kouzani, Abbas Z; Duan, Wei; Dai, Xiujuan J; Kaynak, Akif; Mair, Douglas

2014-02-01

132

Effect of remineralizing agents on bond strength of orthodontic brackets: an in vitro study  

PubMed Central

Background The purpose of this study is to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and CPP-ACP with fluoride (CPP-ACP-F) on the shear bond strength (SBS) of orthodontic brackets bonded with two different adhesive systems. Methods One hundred twenty-six human premolar teeth were selected. One hundred twenty teeth were used for SBS testing, and six teeth were used for scanning electron microscope (SEM) examination. One hundred twenty premolars were divided into mainly three groups: CPP-ACP (group A), CPP-ACP-F (group B), and control group (group C). Each group was sub-divided into two groups according to the bonding adhesive, light cure (groups A1, B1, and C1) and chemical cure (groups A2, B2, and C2). The teeth were pre-treated with the group-specified preventive agent 1 h/day for five consecutive days. Standard edgewise brackets were bonded with the respective adhesives. SBS evaluation was done with the universal testing machine. After debonding, all the teeth were scored for adhesive remaining on the buccal surface, in accordance to adhesive remnant index, under a stereomicroscope. The acid-etched enamel surfaces were observed under SEM after treatment with CPP-ACP, CPP-ACP-F, and artificial saliva. Result In light-cure adhesive group, CPP-ACP-F (B1) showed superior results compared to the control group (C1), whereas the CPP-ACP group (A1) showed lower mean SBS than the control group (C1). Both these differences were not statistically significant (p?>?0.05). In chemical-cure adhesive group, control group C2 showed significantly superior results (p??0.01). Conclusion The SBS of the orthodontic brackets was non-significantly affected when the brackets were cured with light-cure bonding system and treated with either CPP-ACP or CPP-ACP-F, whereas with chemical-cure adhesive, decreased bond strength was seen, which was within the clinically acceptable limits.

2014-01-01

133

A Computational Fluid Dynamic Analysis of Peri-Bracket Salivary Flow Influencing the Microbial and Periodontal Parameters  

PubMed Central

Fixed vestibular appliances decrease the “self-cleansing” action of saliva and promote aggregation of dental plaque by disturbing the salivary flow field on tooth surfaces, leading to a higher prevalence of enamel demineralization and periodontal diseases. In the current study, we investigated the salivary dynamic characteristics of plaque retention and periodontal status around appliances during orthodontic treatment. By reconstructing lower central incisors and orthodontic appliances, we simulated saliva flow on the tooth surface and then characterized and quantified the salivary flow pattern surrounding the bracket and archwire. In parallel, we tested the total peri-bracket bacterial counts and periodontal status to assess interrelations. Our results demonstrate that orthodontic appliances disturb the salivary flow field on tooth surfaces and can lead to a decrease in salivary velocity and an increase in bacterial numbers. Local vortexes forming in the areas gingival to the bracket, together with the narrow space limitation, contributed to the periodontal inflammatory response. This study confirms that changes in salivary flow are an obvious predisposing factor for bacterial accumulation, and advances the ability to replicate, in vitro, the salivary characteristics of plaque retention and periodontal status around appliances during orthodontic treatment.

Zhu, Ping; Lin, Han; Han, Yi; Lin, Yi; Xu, Yue; Zhang, Zhaoqiang

2013-01-01

134

A computational fluid dynamic analysis of peri-bracket salivary flow influencing the microbial and periodontal parameters.  

PubMed

Fixed vestibular appliances decrease the "self-cleansing" action of saliva and promote aggregation of dental plaque by disturbing the salivary flow field on tooth surfaces, leading to a higher prevalence of enamel demineralization and periodontal diseases. In the current study, we investigated the salivary dynamic characteristics of plaque retention and periodontal status around appliances during orthodontic treatment. By reconstructing lower central incisors and orthodontic appliances, we simulated saliva flow on the tooth surface and then characterized and quantified the salivary flow pattern surrounding the bracket and archwire. In parallel, we tested the total peri-bracket bacterial counts and periodontal status to assess interrelations. Our results demonstrate that orthodontic appliances disturb the salivary flow field on tooth surfaces and can lead to a decrease in salivary velocity and an increase in bacterial numbers. Local vortexes forming in the areas gingival to the bracket, together with the narrow space limitation, contributed to the periodontal inflammatory response. This study confirms that changes in salivary flow are an obvious predisposing factor for bacterial accumulation, and advances the ability to replicate, in vitro, the salivary characteristics of plaque retention and periodontal status around appliances during orthodontic treatment. PMID:23620815

Zhu, Ping; Lin, Han; Han, Yi; Lin, Yi; Xu, Yue; Zhang, Zhaoqiang

2013-01-01

135

The effect of herbal teas on the shear bond strength of orthodontic brackets.  

PubMed

The present study was conducted to evaluate the effects of some types of herbal tea on the shear bond strength (SBS) of orthodontic brackets to enamel surfaces. The brackets were bonded with Transbond XT to 90 extracted human premolar teeth and divided equally into six groups, that is, black, mint-mate herbal, mint-lemon herbal, and rosehip fruit tea and two control groups, Coca-Cola and distilled water. All groups were conditioned for three 5-minute sessions with equal intervening intervals for 90 days. The initial pH, SBS, and adhesive remnant index (ARI) of the groups were evaluated and the data were analysed statistically by Kruskal-Wallis and Mann-Whitney U-tests, one-way analysis of variance, and Duncan and Z-tests, respectively. Rosehip fruit tea (2.4 +/- 0.07) and Coca-Cola (2.5 +/- 0.05) had the lowest pH values. Coca-Cola (6.04 +/- 1.11 MPa) and rosehip fruit tea (7.26 +/- 1.11 MPa) significantly reduced the SBS to enamel (P < 0.001). The SBS results for the other groups were similar (P > 0.05). Except for the Coca-Cola group (ARI score = 0), fracture sites for all other groups were similar with the majority of bond failures at the enamel-adhesive interface (ARI score = 1). Although this experiment could not completely replicate the complex oral environment, it seems to confirm that Coca-Cola and rosehip fruit tea may be a causative factor in bracket-enamel bonding failure. PMID:19336626

Ulusoy, Cagri; Müjdeci, Arzu; Gökay, Osman

2009-08-01

136

Bracket positioning and resets: five steps to align crowns and roots consistently.  

PubMed

Orthodontists strive for accurate bracket positioning because it makes achieving a superior occlusion easier. Whether one uses a direct or an indirect bonding technique, the initial appliance placement typically includes some bracket-positioning errors. The clinician either corrects these errors during treatment or tediously repeats archwire bends to compensate for the misplaced brackets. The clinician should assess bracket positioning early in treatment by clinical and radiographic evaluations and then correct all positioning errors during a single dedicated reset appointment. This article describes a 5-step protocol for assessing and correcting bracket-positioning errors. PMID:11174544

Carlson, S K; Johnson, E

2001-01-01

137

An innovative approach for investigating the ceramic bracket-enamel interface - optical coherence tomography and confocal microscopy  

NASA Astrophysics Data System (ADS)

Bonding has become a routine procedure in several dental specialties - from prosthodontics to conservative dentistry and even orthodontics. In many of these fields it is important to be able to investigate the bonded interfaces to assess their quality. All currently employed investigative methods are invasive, meaning that samples are destroyed in the testing procedure and cannot be used again. We have investigated the interface between human enamel and bonded ceramic brackets non-invasively, introducing a combination of new investigative methods - optical coherence tomography (OCT) and confocal microscopy (CM). Brackets were conventionally bonded on conditioned buccal surfaces of teeth The bonding was assessed using these methods. Three dimensional reconstructions of the detected material defects were developed using manual and semi-automatic segmentation. The results clearly prove that OCT and CM are useful in orthodontic bonding investigations.

Romînu, Roxana Otilia; Sinescu, Cosmin; Romînu, Mihai; Negrutiu, Meda; Laissue, Philippe; Mihali, Sorin; Cuc, Lavinia; Hughes, Michael; Bradu, Adrian; Podoleanu, Adrian

2008-12-01

138

Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic.  

PubMed

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (?=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic. PMID:22814690

Costa, Ana Rosa; Correr, Américo Bortolazzo; Puppin-Rontani, Regina Maria; Vedovello, Silvia Amélia; Valdrighi, Heloísa Cristina; Correr-Sobrinho, Lourenço; Vedovello Filho, Mário

2012-01-01

139

Statistical Seasonal Sea Surface based Prediction Model  

NASA Astrophysics Data System (ADS)

The interannual variability of the sea surface temperature (SST) plays a key role in the strongly seasonal rainfall regime on the West African region. The predictability of the seasonal cycle of rainfall is a field widely discussed by the scientific community, with results that fail to be satisfactory due to the difficulty of dynamical models to reproduce the behavior of the Inter Tropical Convergence Zone (ITCZ). To tackle this problem, a statistical model based on oceanic predictors has been developed at the Universidad Complutense of Madrid (UCM) with the aim to complement and enhance the predictability of the West African Monsoon (WAM) as an alternative to the coupled models. The model, called S4CAST (SST-based Statistical Seasonal Forecast) is based on discriminant analysis techniques, specifically the Maximum Covariance Analysis (MCA) and Canonical Correlation Analysis (CCA). Beyond the application of the model to the prediciton of rainfall in West Africa, its use extends to a range of different oceanic, atmospheric and helth related parameters influenced by the temperature of the sea surface as a defining factor of variability.

Suarez, Roberto; Rodriguez-Fonseca, Belen; Diouf, Ibrahima

2014-05-01

140

Comparative Evaluation of Shear Bond Strength of Orthodontic Brackets on Pretreatment with CPPACP, Fluor Protector and Phosflur: An In-vitro Study  

PubMed Central

Objective: The purpose of this study is to evaluate bond strength, bracket tooth interface of Orthodontic brackets that are bonded for fixed Orthodontic treatment procedure on pretreatment with CPPACP, Fluor Protector and Phosflur. The goal is to assess the adhesive remnants following application of these remineralizing agents using Adhesive Remnant Index. Materials and Methods: Two hundred freshly extracted premolar teeth each divided into Control, CPP-ACP, Fluor Protector and Phosflur. Teeth were pretreated with these agents prior to bonding procedure. Shear Bond Strength was tested using a Universal Testing Machine. A jig was attached to upper jaw of the machine. The acrylic block containing the embedded teeth was secured in the lower jaw of the machine such that the bracket base of the teeth parallel the direction of the shear force at a crosshead speed of 1 mm/minute until bracket failure. The force required to dislodge the bracket was recorded. Results: Mean Shear bond strength value is highest for Phosflur (15.3658 ± 2.4546 ) followed by Fluor Protector , CPP-ACP and lowest for Control (7.0462 ± 0.8838 MPa). Conclusion: Phosflur, Fluor protector,CPP-ACP have comparable Shear bond strength values in comparison to control.

2014-01-01

141

Nuclear techniques to identify allergenic metals in orthodontic brackets  

Microsoft Academic Search

The present study determines the elementary alloy composition of ten commercial brands of brackets, especially related to\\u000a Ni, Cr, and Co metals, confirmed allergenic elements. The nuclear techniques applied in the analyses were X-ray fluorescence\\u000a (XRF) — Centre National de la Recherche Scientifique, France (National Center of Scientific Research), and X-ray energy spectrometry\\u000a (XRES), and Instrumental Neutron Activation Analysis (INAA)

E. G. Zenóbio; M. A. F. Zenóbio; M. C. G. Pantuzo; M. Â. B. C. Menezes

2009-01-01

142

12. FLOOR BEAMS, BRACKETS, STRINGERS. (Also includes a schedule of ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. FLOOR BEAMS, BRACKETS, STRINGERS. (Also includes a schedule of parts.) American Bridge Company, Ambridge Plant No. 5, sheet no. 2, dated April 2, 1928 (revised 4-24-28), order no. F5073. For U.S. Steel Products Company, Pacific Coast Depot, order no. SF578. For Southern Pacific Company, order no. 8873-P-28746. Scale 1/4 inch to one foot. - Napa River Railroad Bridge, Spanning Napa River, east of Soscol Avenue, Napa, Napa County, CA

143

Surface Functionalization of Graphene-based Materials  

NASA Astrophysics Data System (ADS)

Graphene-based materials have generated tremendous interest in the past decade. Manipulating their characteristics using wet-chemistry methods holds distinctive value, as it provides a means towards scaling up, while not being limited by yield. The majority of this thesis focuses on the surface functionalization of graphene oxide (GO), which has drawn tremendous attention as a tunable precursor due to its readily chemically manipulable surface and richly functionalized basal plane. Firstly, a room-temperature based method is presented to reduce GO stepwise, with each organic moiety being removed sequentially. Characterization confirms the carbonyl group to be reduced first, while the tertiary alcohol is reduced last, as the optical gap decrease from 3.5 eV down to 1 eV. This provides greater control over GO, which is an inhomogeneous system, and is the first study to elucidate the order of removal of each functional group. In addition to organically manipulating GO, this thesis also reports a chemical methodology to inorganically functionalize GO and tune its wetting characteristics. A chemical method to covalently attach fluorine atoms in the form of tertiary alkyl fluorides is reported, and confirmed by MAS 13C NMR, as two forms of fluorinated graphene oxide (FGO) with varying C/F and C/O ratios are synthesized. Introducing C-F bonds decreases the overall surface free energy, which drastically reduces GO's wetting behavior, especially in its highly fluorinated form. Ease of solution processing leads to development of sprayable inks that are deposited on a range of porous and nonporous surfaces to impart amphiphobicity. This is the first report that tunes the wetting characteristics of GO. Lastly as a part of a collaboration with ConocoPhillips, another class of carbon nanomaterials - carbon nanotubes (CNTs), have been inorganically functionalized to repel 30 wt% MEA, a critical solvent in CO 2 recovery. In addition to improving the solution processability of CNTs, composite, homogeneous solutions are created with polysulfones and polyimides to fabricate CNT-polymer nanocomposites that display contact angles greater than 150o with 30 wt% MEA. This yields materials that are inherently supersolvophobic, instead of simply surface treating polymeric films, while the low density of fluorinated CNTs makes them a better alternative to superhydrophobic polymer materials.

Mathkar, Akshay

144

Construction of Low-Discrepancy Point Sets of Small Size by Bracketing Covers and Dependent Randomized Rounding  

Microsoft Academic Search

We provide a deterministic algorithm that constructs small point sets exhibiting a low star discrepancy. The algorithm is\\u000a based on bracketing and on recent results on randomized roundings respecting hard constraints. It is structurally much simpler\\u000a than the previous algorithm presented for this problem in [B. Doerr, M. Gnewuch, A. Srivastav. Bounds and constructions for\\u000a the star discrepancy via ?-covers.

Benjamin Doerr; Michael Gnewuch

145

A comparative assessment of torque generated by lingual and conventional brackets.  

PubMed

The aim of this study was to assess the effect of bracket type on the labiopalatal moments generated by lingual and conventional brackets. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), In-Ovation L lingual brackets (DENTSPLY GAC), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on identical maxillary acrylic resin models with levelled and aligned teeth. Each model was mounted on the orthodontic measurement and simulation system and 10 0.0175 × 0.0175 TMA wires were used for each bracket type. The wire was ligated with elastomerics into the Incognito, STb, and conventional brackets and each measurement was repeated once after religation. A 15 degrees buccal root torque (+15 degrees) and then a 15 degrees palatal root torque (-15 degrees) were gradually applied to the right central incisor bracket. After each activation, the bracket returned to its initial position and the moments in the sagittal plane were recorded during these rotations of the bracket. One-way analysis of variance with post hoc multiple comparisons (Tukey test at 0.05 error rate) was conducted to assess the effect on bracket type on the generated moments. The magnitude of maximum moment at +15 degrees ranged 8.8, 8.2, 7.1, and 5.8 Nmm for the Incognito, STb, conventional Gemini, and the In-Ovation L brackets, respectively; similar values were recorded at -15 degrees: 8.6, 8.1, 7.0, and 5.7 Nmm, respectively. The recorded differences of maximum moments were statistically significant, except between the Incognito and STb brackets. Additionally, the torque angles were evaluated at which the crown torque fell well below the minimum levels of 5.0 Nmm, as well as the moment/torque ratio at the last part of the activation/deactivation curve, between 10 and 15 degrees. The lowest torque expression was observed at the self-ligating lingual brackets, followed by the conventional brackets. The Incognito and STb lingual brackets generated the highest moments. PMID:22573909

Sifakakis, Iosif; Pandis, Nikolaos; Makou, Margarita; Eliades, Theodore; Katsaros, Christos; Bourauel, Christoph

2013-06-01

146

Evaluation of shear bond strength of orthodontic brackets bonded with Er-YAG laser etching  

PubMed Central

Background: Based on contradictory findings concerning the use of lasers for enamel etching, the purpose of this study was to investigate the shear bond strength of teeth prepared for bonding with Er-YAG laser etching and compare them with phosphoric acid etching. Materials and Methods: In this in vitro study forty – eight premolars, extracted for orthodontic purposes were randomly divided in to three groups. Thirty-two teeth were exposed to laser energy for 25 s: 16 teeth at 100 mj setting and 16 teeth at 150 mj setting. Sixteen teeth were etched with 37% phosphoric acid. The shear bond strength of bonded brackets with the Transbond XT adhesive system was measured with the Zwick testing machine. Descriptive statistics, Kolmogorov–Smirnov test, of homogeneity of variances, one- way analysis of variances and Tukey's test and Kruskal Wallis were used to analyze the data. Results: The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa). Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P < 0.001). Conclusions: laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive – enamel interface and is not safe for enamel during debonding.

Raji, S. Hamid; Birang, Reza; Majdzade, Fateme; Ghorbanipour, Reza

2012-01-01

147

Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared By Er:YAG Laser and Conventional Acid-Etching  

PubMed Central

Introduction: The purpose of this study was to compare shear bond strength (SBS) of orthodontic brackets bonded to enamel prepared by Er:YAG laser with two different powers and conventional acid-etching. Materials and Methods: Forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group 1- conventional etching with 37% phosphoric acid; Group 2- irradiation with Er:YAG laser at 1 W; and Group 3- irradiation with Er:YAG laser at 1.5 W. Metal brackets were bonded on prepared enamel using a light-cured composite. All groups were subjected to thermocycling process. Then, the specimens mounted in auto-cure acryle and shear bond strength were measured using a universal testing machine with a crosshead speed of 0.5 mm per second. After debonding, the amount of resin remaining on the teeth was determined using the adhesive remnant index (ARI) scored 1 to 5. One-way analysis of variance was used to compare shear bond strengths and the Kruskal-Wallis test was performed to evaluate differences in the ARI for different etching types. Results: The mean and standard deviation of conventional acid-etch group, 1W laser group and 1.5W laser group was 3.82 ± 1.16, 6.97 ± 3.64 and 6.93 ± 4.87, respectively. Conclusion: The mean SBS obtained with an Er:YAG laser operated at 1W or 1.5W is approximately similar to that of conventional etching. However, the high variability of values in bond strength of irradiated enamel should be considered to find the appropriate parameters for applying Er:YAG laser as a favorable alternative for surface conditioning.

Hosseini, M.H.; Namvar, F.; Chalipa, J.; Saber, K.; Chiniforush, N.; Sarmadi, S.; Mirhashemi, A.H.

2012-01-01

148

Robust Toponym Resolution Based on Surface Statistics  

NASA Astrophysics Data System (ADS)

Toponyms and other named entities are main issues in unknown word processing problem. Our purpose is to salvage unknown toponyms, not only for avoiding noises but also providing them information of area candidates to where they may belong. Most of previous toponym resolution methods were targeting disambiguation among area candidates, which is caused by the multiple existence of a toponym. These approaches were mostly based on gazetteers and contexts. When it comes to the documents which may contain toponyms worldwide, like newspaper articles, toponym resolution is not just an ambiguity resolution, but an area candidate selection from all the areas on Earth. Thus we propose an automatic toponym resolution method which enables to identify its area candidates based only on their surface statistics, in place of dictionary-lookup approaches. Our method combines two modules, area candidate reduction and area candidate examination which uses block-unit data, to obtain high accuracy without reducing recall rate. Our empirical result showed 85.54% precision rate, 91.92% recall rate and .89 F-measure value on average. This method is a flexible and robust approach for toponym resolution targeting unrestricted number of areas.

Sano, Tomohisa; Nobesawa, Shiho Hoshi; Okamoto, Hiroyuki; Susuki, Hiroya; Matsubara, Masaki; Saito, Hiroaki

149

Evaluation of Friction in Orthodontics Using Various Brackets and Archwire Combinations-An in Vitro Study  

PubMed Central

AIM: The aim of this study was to compare frictional resistance which was produced between conventional brackets (0.022 slot Otho-Organiser) and self ligating brackets (active Forestadent and passive Damon III) by using various arch wire combinations (0.016 Niti, 0.018 Niti, 0.017 x 0.025 SS and 0.019 x 0.025 SS). Methods: An experimental model which consisted of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces which were produced by SLBs (self ligating brackets) and CELs (conventional elastomeric ligatures) with use of 0.016 nickel titanium, 0.018 nickel titanium, 0.017 X 0.025”stainless steel and 0.019 X 0.025”stainless steel wires. Statistical analysis: One way ANOVA test was used to study the effect of the bracket type, wire alloy and section on frictional resistance test . Results: Conventional brackets produced highest levels of friction for all bracket/archwire combinations. Both Damon III and Forestadent brackets were found to produce significantly lower levels of friction when they were compared with elastomerically tied conventional brackets. Conclusion: SLBs are valid alternatives for low friction during sliding mechanics.

Kumar, Sujeet; Hamsa P.R, Rani; Ahmed, Sameer; Prasanthma; Bhatnagar, Apoorva; Sidhu, Manreet; Shetty, Pramod

2014-01-01

150

Elemental composition of brazing alloys in metallic orthodontic brackets.  

PubMed

The aim of this study was to assess the elemental composition of the brazing alloy of representative orthodontic brackets. The brackets examined were Gemini (3M, Unitec, Monrovia, Calif), MicroLoc (GAC, Bohemia, NY), OptiMESHxrt (Ormco, Glendora, Calif), and Ultratrim (Dentarum, Ispringen, Germany). Four metallic brackets for each brand were embedded in epoxy resin and after metallographic grinding and polishing were cleaned in a water ultrasonic bath. Scanning electron microscopy and energy-dispersive x-ray microanalysis (EDS) were used to assess the quantitative composition of the brazing alloy. Four EDS spectra were collected for each brazing alloy, and the mean value and standard deviation for the concentration of each element were calculated. The elemental composition of the brazing alloys was determined as follows (percent weight): Gemini: Ni = 83.98 +/- 1.02, Si = 6.46 +/- 0.37, Fe = 5.90 +/- 0.93, Cr = 3.52 +/- 0.34; MicroLoc: Ag = 42.82 +/- 0.18, Au = 32.14 +/- 0.65, Cu = 24.53 +/- 0.26, Mg = 1.12 +/- 0.33; OptiMESHxrt: Au = 67.79 +/- 0.97, Fe = 15.69 +/- 0.29, Ni = 13.01 +/- 0.93, Cr = 4.01 +/- 0.35; Ultratrim: Ag = 87.97 +/- 0.33, Cu = 10.51 +/- 0.45, Mg = 1.29 +/- 0.63, Zn = 1.13 +/- 0.24. The findings of this study showed that different brazing materials were used for the different brands, and thus different performances are expected during intraoral exposure; potential effects on the biological properties also are discussed. PMID:15264653

Zinelis, Spiros; Annousaki, Olga; Eliades, Theodore; Makou, Margarita

2004-06-01

151

GLDAS Land Surface Models based Aridity Indices  

NASA Astrophysics Data System (ADS)

Identification of dryland areas is crucial to guide policy aimed at intervening in water stressed areas and addressing its perennial livelihood or food insecurity. Aridity indices based on spatially relative soil moisture conditions such as NCEP aridity index allow cross comparison of dry conditions between sites. NCEP aridity index is based on the ratio of annual precipitation (supply) to annual potential evaporation (demand). Such an index ignores subannual scale competition between evaporation and drainage functions well as rainfall and temperature regimes. This determines partitioning of annual supply of precipitation into two competing (but met) evaporation and runoff demands. We here introduce aridity indices based on these additional considerations by using soil moisture time series for the past 3 decades from three Land Surface Models (LSM) models and compare it with NCEP index. We analyze global monthly soil moisture time series (385 months) at 1 x 1 degree spatial resolution as modeled by three GLDAS LSMs - VIC, MOSAIC and NOAH. The first eigen vector from Empirical Orthogonal Function (EOF) analysis, as it is the most dominant spatial template of global soil moisture conditions, is extracted. Frequency of nonexceedences of this dominant soil moisture mode for a location by other locations is calculated and is used as our proposed aridity index. An area is indexed drier (relative to other areas in the world) if its frequency of nonexceedence is lower. The EOF analysis reveals that their first eigen vector explains approximately 32%, 43% and 47% of variance explained by first 385 eigen vectors for VIC, MOSAIC and NOAH respectively. The temporal coefficients associated with it for all three LSMS show seasonality with a jump in trend around the year 1999 for NOAH and MOSAIC. The VIC aridity index displays a pattern most closely resembling that of NCEP though all LSM based indices isolate dominant dryland areas. However, all three LSMs identify some parts of south central Africa, southeast United States and eastern India as drier than NCEP classification. NOAH and MOSAIC indentify parts of Western Africa drier than the other two classifications, while NOAH and VIC indentify parts of central India as wetter than the other two classifications.

Pande, S.; Ghazanfari, S.

2011-12-01

152

Maslov indices, Poisson brackets, and singular differential forms  

NASA Astrophysics Data System (ADS)

Maslov indices are integers that appear in semiclassical wave functions and quantization conditions. They are often notoriously difficult to compute. We present methods of computing the Maslov index that rely only on typically elementary Poisson brackets and simple linear algebra. We also present a singular differential form, whose integral along a curve gives the Maslov index of that curve. The form is closed but not exact, and transforms by an exact differential under canonical transformations. We illustrate the method with the 6j-symbol, which is important in angular-momentum theory and in quantum gravity.

Esterlis, I.; Haggard, H. M.; Hedeman, A.; Littlejohn, R. G.

2014-06-01

153

Dental plaque associated with self-ligating brackets during the initial phase of orthodontic treatment: A 3-month preliminary study  

PubMed Central

Background: To compare changes in the amount and distribution of dental plaque associated with placement of elastomeric modules over a self-ligating bracket during orthodontic treatment and to relate these changes to the periodontal inflammation. Materials and Methods: A cross-arch randomization trial was carried out at Bristol Dental School, United Kingdom. Clinical measurements of periodontal inflammation and plaque accumulation and microbiological test were done on 24 patients aged 11-14 years [Mean (SD) age = 12.6 (1.01) years] wearing fixed appliances (Damon 2 brackets, Ormco, Orange, CA, USA) at the start and 3 months into fixed orthodontic treatment. Results: In the first 3 months of treatment there was no statistically significant difference in bleeding on probing between incisors with and without elastomeric modules (P = 0.125 and 0.508, respectively). The difference in plaque accumulation was not statistically significant (P = 0.78). The difference in probing depths between the incisors was not statistically significant (P = 0.84). The microbiological analysis showed no difference. Conclusions: Based on this preliminary 3 months study, elastomeric modules were not significantly associated with any increased risk during treatment when compared to self-ligating brackets. The longer term studies are needed to further confirm the findings of the present study.

Al-Anezi, Saud A

2014-01-01

154

A comparison of the frictional characteristics of five initial alignment wires and stainless steel brackets at three bracket to wire angulations--an in vitro study.  

PubMed

The study investigated static planar frictional resistance between five initial alignment wires and stainless steel brackets at three bracket to wire angulations (0, 5 and 10 degrees). It was demonstrated that static frictional resistance increased significantly with increasing bracket to wire angulation due to binding within the system. Epoxy-coated steel had the highest static frictional resistance and coaxial stainless steel the lowest. Fibre-optic glass (Optiflex) had low frictional resistance. The coefficient of friction followed the trends of static frictional resistance in all respects. PMID:8199160

Dickson, J A; Jones, S P; Davies, E H

1994-02-01

155

Options for a lunar base surface architecture  

NASA Technical Reports Server (NTRS)

The Planet Surface Systems Office at the NASA Johnson Space Center has participated in an analysis of the Space Exploration Initiative architectures described in the Synthesis Group report. This effort involves a Systems Engineering and Integration effort to define point designs for evolving lunar and Mars bases that support substantial science, exploration, and resource production objectives. The analysis addresses systems-level designs; element requirements and conceptual designs; assessments of precursor and technology needs; and overall programmatics and schedules. This paper focuses on the results of the study of the Space Resource Utilization Architecture. This architecture develops the capability to extract useful materials from the indigenous resources of the Moon and Mars. On the Moon, a substantial infrastructure is emplaced which can support a crew of up to twelve. Two major process lines are developed: one produces oxygen, ceramics, and metals; the other produces hydrogen, helium, and other volatiles. The Moon is also used for a simulation of a Mars mission. Significant science capabilities are established in conjunction with resource development. Exploration includes remote global surveys and piloted sorties of local and regional areas. Science accommodations include planetary science, astronomy, and biomedical research. Greenhouses are established to provide a substantial amount of food needs.

Roberts, Barney B.

1992-01-01

156

Carbon nanotube-based robust steamphobic surfaces.  

PubMed

The wetting behavior of a surface under steam condensation depends on its intrinsic wettability and micrometer or nanoscale surface roughness. A typical superhydrophobic surface may not be suitable as a steamphobic surface because of the nucleation and growth of water inside the valleys and thus the failure to form an air-liquid-solid composite interface. Here, we present the results of steam condensation on chemically modified nanostructured carbon nanotube (CNT) mats. We used a plasma-enhanced chemical vapor deposition (PECVD) process to modify the intrinsic wettability of nanostructured CNT mats. The combination of low surface energy achieved by PECVD and the nanoroughness of the surface provides a mechanism to retain the superhydrophobicity of the CNT mats under steam condensation. The ability to withstand steam temperature and pressure for as long as 10 h implies the remarkably improved stability of the superhydrophobic state of the surface. The thermodynamic calculations carried out using a unit cell model clearly explain the steamphobic wetting behavior of the surface. PMID:22087571

Badge, Ila; Sethi, Sunny; Dhinojwala, Ali

2011-12-20

157

Electrical servo actuator bracket. [fuel control valves on jet engines  

NASA Technical Reports Server (NTRS)

An electrical servo actuator is mounted on a support arm which is allowed to pivot on a bolt through a fixed mounting bracket. The actuator is pivotally connected to the end of the support arm by a bolt which has an extension allowed to pass through a slot in the fixed mounting bracket. An actuator rod extends from the servo actuator to a crank arm which turns a control shaft. A short linear thrust of the rod pivots the crank arm through about 90 for full-on control with the rod contracted into the servo actuator, and full-off control when the rod is extended from the actuator. A spring moves the servo actuator and actuator rod toward the control crank arm once the actuator rod is fully extended in the full-off position. This assures the turning of the control shaft to a full-off position. A stop bolt and slot are provided to limit pivot motion. Once fully extended, the spring pivots the motion.

Sawyer, R. V. (inventor)

1981-01-01

158

Revised calculation of four-particle harmonic-oscillator transformation brackets matrix  

NASA Astrophysics Data System (ADS)

In this article we present a new, considerably enhanced and more rapid method for calculation of the matrix of four-particle harmonic-oscillator transformation brackets (4HOB). The new method is an improved version of 4HOB matrix calculations which facilitates the matrix calculation by finding the eigenvectors of the 4HOB matrix explicitly. Using this idea the new Fortran code for fast and 4HOB matrix calculation is presented. The calculation time decreases more than a few hundred times for large matrices. As many problems of nuclear and hadron physics structure are modeled on the harmonic oscillator (HO) basis our presented method can be useful for large-scale nuclear structure and many-particle identical fermion systems calculations. Program summaryTitle of program: HOTB_M Catalogue identifier: AEFQ_v3_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFQ_v3_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 2149 No. of bytes in distributed program, including test data, etc.: 17576 Distribution format: tar.gz Programming language: Fortran 90. Computer: Any computer with Fortran 90 compiler. Operating system: Windows, Linux, FreeBSD, True64 Unix. RAM: Up to a few Gigabytes (see Tables 1 and 2 included in the distribution package) Classification: 17.16, 17.17. Catalogue identifier of previous version: AEFQ_v2_0 Journal reference of previous version: Comput. Phys. Comm. 182(2011)1377 Does the new version supersede the previous version?: Yes Nature of problem: Calculation of the matrix of the 4HOB in a more effective way, which allows us to calculate the matrix of the brackets up to a few hundred times more rapidly than in a previous version. Solution method: The method is based on compact expressions of 4HOB, presented in [1] and its simplifications presented in this paper. Reasons for new version: We facilitated the calculation of the 4HOB, based on the method presented in the section 'Theoretical aspects'. The new program version gives shorter calculation times for the 4HOB Summary of revisions: New subroutines for calculation of the matrix of the 4HOB. For theoretical issues of revision see the section 'Theoretical aspects'. Restrictions: The 4HOB matrices up to e=28. Running time: Depends on the dimension of the 4HOB matrix (see Tables 1 and 2 included in the distribution file). References: [1] D. Germanas, S. Mickevicius, R.K. Kalinauskas, Calculation of four-particle harmonic-oscillator transformation brackets, Computer Physics Communications 181, 420-425 (2010).

Mickevi?ius, S.; Germanas, D.; Kalinauskas, R. K.

2013-02-01

159

Friction Forces during Sliding of Various Brackets for Malaligned Teeth: An In Vitro Study  

PubMed Central

Aims. To measure the friction force generated during sliding mechanics with conventional, self-ligating (Damon 3 mx, Smart Clip, and Time 3) and low-friction (Synergy) brackets using different archwire diameters and ligating systems in the presence of apical and buccal malalignments of the canine. Methods. An experimental setup reproducing the right buccal segment of the maxillary arch was designed to measure the friction force generated at the bracket/wire and wire/ligature interfaces of different brackets. A complete factorial plan was drawn up and a three-way analysis of variance (ANOVA) was carried out to investigate whether the following factors affect the values of friction force: (i) degree of malalignment, (ii) diameter of the orthodontic wire, and (iii) bracket/ligature combination. Tukey post hoc test was also conducted to evaluate any statistically significant differences between the bracket/ligature combinations analyzed. Results. ANOVA showed that all the above factors affect the friction force values. The friction force released during sliding mechanics with conventional brackets is about 5-6times higher than that released with the other investigated brackets. A quasilinear increase of the frictional forces was observed for increasing amounts of apical and buccal malalignments. Conclusion. The Synergy bracket with silicone ligature placed around the inner tie-wings appears to yield the best performance.

Crincoli, Vito; Di Bisceglie, Maria Beatrice; Balsamo, Antonio; Serpico, Vitaliano; Chiatante, Francesco; Pappalettere, Carmine; Boccaccio, Antonio

2013-01-01

160

In vitro physical, chemical, and biological evaluation of commercially available metal orthodontic brackets  

PubMed Central

Objective This in vitro study was undertaken to evaluate the physical, chemical, and biological properties of commercially available metal orthodontic brackets in South Korea, because national standards for these products are lacking. Methods Four bracket brands were tested for dimensional accuracy, (manufacturing errors in angulation and torque), cytotoxicity, composition, elution, and corrosion: Archist (Daeseung Medical), Victory (3M Unitek), Kosaka (Tomy), and Confidence (Shinye Odontology Materials). Results The tested rackets showed no significant differences in manufacturing errors in angulation, but Confidence brackets showed a significant difference in manufacturing errors in torque. None of the brackets were cytotoxic to mouse fibroblasts. The metal ion components did not show a regular increasing or decreasing trend of elution over time, but the volume of the total eluted metal ions increased: Archist brackets had the maximal Cr elution and Confidence brackets appeared to have the largest volume of total eluted metal ions because of excessive Ni elution. Confidence brackets showed the lowest corrosion resistance during potentiodynamic polarization. Conclusions The results of this study could potentially be applied in establishing national standards for metal orthodontic brackets and in evaluating commercially available products.

Kim, Joo Hyoung; Cha, Jung Yul

2012-01-01

161

Effect of tooth layers' segmentation on pattern of stress distribution in bracket adhesive tooth system  

Microsoft Academic Search

Orthodontic braces are used to modify, malocclusions of teeth and jaws. Most of problems in dentistry can be investigated from a biomechanical point of view. Stress distribution in bracket, adhesive and tooth has been used as a criterion to determine bond strength of bracket- adhesive- tooth system. Tooth is consisted of three layers including enamel, dentin and pulp with three

Maryam Hajizadeh; Behnam Mirzakouchaki; Farzan Ghalichi

2011-01-01

162

Experience With Bayesian Image Based Surface Modeling  

NASA Astrophysics Data System (ADS)

Bayesian surface modeling from images requires modeling both the surface and the image generation process, in order to optimize the models by comparing actual and generated images. Thus it differs greatly, both conceptually and in computational difficulty, from conventional vusual surface recovery techniques. But it offers the possibility of generating a single surface model that fuses all available information, from any number of images, taken under quite different conditions, and by different instruments that provide independent and often complementary information. I describe an implemented system, with a brief introduction to the underlying mathematical models and the compromises made for computational efficiency. I describe successes and failures achieved on actual imagery, where we went wrong and what we did right, and how our approach could be improved. Lastly I discuss how the same approach can be extended to distinct types of instruments, to achieve true sensor fusion.

Stutz, John C.

2005-11-01

163

Experience With Bayesian Image Based Surface Modeling  

NASA Technical Reports Server (NTRS)

Bayesian surface modeling from images requires modeling both the surface and the image generation process, in order to optimize the models by comparing actual and generated images. Thus it differs greatly, both conceptually and in computational difficulty, from conventional stereo surface recovery techniques. But it offers the possibility of using any number of images, taken under quite different conditions, and by different instruments that provide independent and often complementary information, to generate a single surface model that fuses all available information. I describe an implemented system, with a brief introduction to the underlying mathematical models and the compromises made for computational efficiency. I describe successes and failures achieved on actual imagery, where we went wrong and what we did right, and how our approach could be improved. Lastly I discuss how the same approach can be extended to distinct types of instruments, to achieve true sensor fusion.

Stutz, John C.

2005-01-01

164

A three-year clinical trial using a glass ionomer cement for the bonding of orthodontic brackets.  

PubMed

Recent clinical studies measuring orthodontic bracket failure, when using glass ionomer cement as an adhesive, have reported a wide range of percentages of bracket failure. The present study recorded bracket failure over a 3-year period, longer than had been previously measured. Seventeen participants were randomly assigned to one of two treatment groups, either using glass ionomer cement or composite resin for bonding. In each group, brackets were bonded to incisors, canines, and premolars. Bracket failure was measured over the duration of comprehensive orthodontic treatment for all participants. Brackets bonded with the glass ionomer cement were more likely to fail (log-rank test; P < or = 0.022). This difference was clinically significant. At the present time, the disadvantage of extra bracket failures appears to outweigh potential advantages when considering glass ionomer cement for the routine bonding of orthodontic brackets. PMID:8863967

Miller, J R; Mancl, L; Arbuckle, G; Baldwin, J; Phillips, R W

1996-01-01

165

Local Reconstruction and Visualization of Point-Based Surfaces Using Subdivision Surfaces  

Microsoft Academic Search

Point-Based Surfaces, i.e. surfaces represented by discrete point sets which are either directly obtained by current 3D acquisition devices or converted from other surface representations, are well designed for multiresolution storage and transmission of complex objects. Unfortunately, visualization of point-based surfaces requires to develop specic rendering techniques (e.g. splat- ting) since point sets are not well adapted to existing graphics

Tamy Boubekeur; Patrick Reuter; Christophe Schlick

2006-01-01

166

Cytotoxic effects of the nickel release from the stainless steel brackets: An in vitro study  

PubMed Central

Aims: The purpose of the study is to determine whether the nickel released from the stainless steel brackets have any cytotoxic effects on gingival fibroblast. Materials and Methods: Brackets are an important component of fixed orthodontics. Orthodontists are mainly concerned about the brands and various systems incorporated into the brackets. The manufactures claim bracket superiority without valid research. Since we are dealing with a biologic system factors like biocompatibility, cytotoxic potential should be taken into consideration before selecting an appliance to the patient. The cytotoxic activity of the media was investigated with MTT and comet assay. Results: The results of the study show that the amount of nickel leached is capable of bringing damage to the fibroblast. Conclusion: Our study concludes that nickel solution at minimal concentration of 1.18 ?g could damage human gingival fibroblast and the nickel released from the different brands of the brackets are not uniform.

Pillai, Ajith Rajasekharan; Gangadharan, Anil; Gangadharan, Jithin; Kumar, Nallasamy Vijaya

2013-01-01

167

Surface albedo based on geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore is a sensitive indicator of environmental changes. To this end, surface albedo is identified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). NOAA's National Climatic Data Center (NCDC) is implementing the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for GOES data in support of an activity of the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM). SCOPE-CM helps coordinate ECV production responding to GCOS, WMO, and CEOS goals. The GSA algorithm was developed jointly by EUMETSAT and Joint Research Centre (JRC) using a method proposed by Pinty et al. (2000) to retrieve surface albedo by processing day-time, cloud-free geostationary observations from a single visible band. Currently, the GSA algorithm generates products operationally at EUMETSAT using geostationary data from satellites at 0° and 63°E and at JMA using 140°E geostationary data. To support development of an aggregate global albedo product, NCDC will apply the GSA algorithm to data from GOES-E (75°W) and GOES-W (135°W). For the GOES implementation, raw GOES observations are calibrated against AVHRR reflectance data available in PATMOS-x. Surface angular anisotropy is then determined through the inversion of the GSA radiative transfer model using multiple geostationary images collected over a day under different illumination conditions. The inversion process additionally requires ancillary total column ozone and water vapor values, which for the GOES implementation are acquired from the 20th Century Reanalysis V2 data set provided by the NOAA/OAR/ESRL PSD. The GSA algorithm produces a 10-day composite surface albedo map. This product will initially be developed for the period 2000-2003. Later, it will be applied to the complete GOES data collection (1978-present) as part of NOAA's Climate Data Record Program.

Matthews, J. L.; Lattanzio, A.; Hankins, B.; Inamdar, A.; Knapp, K.; Privette, J. L.

2011-12-01

168

In Vitro Effects of Two Topical Varnish Materials and Er:YAG Laser Irradiation on Enamel Demineralization around Orthodontic Brackets  

PubMed Central

The aim of this in vitro was to evaluate the effects of tricalcium phosphate (TCP) and amorphous calcium phosphate (ACP) containing varnish materials and Er:YAG laser irradiation on enamel demineralization around orthodontic brackets. Forty extracted human premolar teeth were randomly divided into four treatment groups (i.e., 10 in each group): (1) 5% NaF-ACP varnish, (2) 5% NaF-TCP varnish, (3) Er:YAG laser, and (4) control (no treatment). Er:YAG laser was operated at a wavelength of 2.94??m and the energy output was 80?mJ per pulse; a pulse duration of 200??sec and and a frequency of 2?Hz were used with water cooling. All samples were then put into pH cycles. Surface microhardness values and representative SEM images were assessed. Surface microhardness values were evaluated using Kruskal-Wallis and Mann-Whitney U tests. The results revealed that demineralization was significantly lower in the TCP and ACP varnish groups, whereas mean surface microhardness values of the TCP varnish were found higher than the ACP (P < 0.05). TCP and ACP varnish materials were found effective for reducing enamel demineralization around orthodontic brackets. Use of Er:YAG laser irradiation as described in this study for inhibition of demineralization was found not satisfactory.

Sungurtekin Ekci, Elif; Sandalli, Nuket

2014-01-01

169

Tools for quality assessment of surface-based flux measurements  

Microsoft Academic Search

The Navier-Stokes equations, after application of the Reynolds' averaging procedures, are the basis of direct surface-based measurements of turbulent fluxes via the eddy correlation method. Under restrictive conditions in the atmospheric surface layer, these equations are valid in a simplified form. These conditions are the stationarity of the data, the homogeneity of the underlying surface, a fully developed turbulence, and

Th. Foken; B. Wichura

1996-01-01

170

Surface characterization based on optical phase shifting interferometry  

DOEpatents

Apparatus, techniques and systems for implementing an optical interferometer to measure surfaces, including mapping of instantaneous curvature or in-plane and out-of-plane displacement field gradients of a sample surface based on obtaining and processing four optical interferograms from a common optical reflected beam from the sample surface that are relatively separated in phase by .pi./2.

Mello, Michael (Pasadena, CA), Rosakis; Ares J. (Altadena, CA)

2011-08-02

171

Correction of palatally displaced maxillary lateral incisors without brackets  

PubMed Central

This article describes the orthodontic treatment of a 25-year-old Korean female patient with anterior crowding, including palatally displaced lateral incisors. Her facial profile was satisfactory, but 3.5 mm of maxillary anterior crowding was observed. To correct this crowding, we decided to minimize the use of the conventional fixed orthodontic appliances and employed a less bulky and more aesthetic appliance for applying light continuous force. We determined the final positions of the maxillary teeth via a working model for diagnostic set up and achieved space gaining and alignment with simple Ni-Ti spring and stainless steel round tubes. Tooth alignment was achieved efficiently and aesthetically without the conventional brackets.

Choi, Kyung-Hee; Lee, Yoonjung; Kim, Minji

2013-01-01

172

Nanostructure-Based Localized Surface Plasmon Resonance Biosensors  

NASA Astrophysics Data System (ADS)

This chapter reviews the characteristics of localized surface plasmon resonance (LSPR), the excitation of which is mediated by nanostructures, and its applications to biosensing. The LSPR is explored in three regimes in terms of creation and coupling of localized surface plasmons (LSPs): LSPs created in surface-relief patterns coupled to propagating surface plasmons (SPs), LSPs in surface-relief patterns coupled to particle plasmons, and LSPs created in particles. The results, in general, suggest that localized field enhancement in the near-field be correlated with enhanced detection sensitivity for LSPR over conventional thin film-based SP resonance while LSPR-based biosensors can potentially maintain flexibility by using nanoparticles.

Kim, Donghyun

173

Nanoparticle-based etching of silicon surfaces  

DOEpatents

A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

Branz, Howard (Boulder, CO); Duda, Anna (Denver, CO); Ginley, David S. (Evergreen, CO); Yost, Vernon (Littleton, CO); Meier, Daniel (Atlanta, GA); Ward, James S. (Golden, CO)

2011-12-13

174

Surfaced-Based Investigations Plan, Volume 4. Yucca Mountain Project.  

National Technical Information Service (NTIS)

This document represents a detailed summary of design plans for surface-based investigations to be conducted for site characterization of the Yucca Mountain site. These plans are current as of December 1988. The description of surface-based site character...

1988-01-01

175

Ion Beam Analysis Of Silicon-Based Surfaces And Correlation With Surface Energy Measurements  

NASA Astrophysics Data System (ADS)

The water affinity of Si-based surfaces is quantified by contact angle measurement and surface free energy to explain hydrophobic or hydrophilic behavior of silicone, silicates, and silicon surfaces. Surface defects such as dangling bonds, surface free energy including Lewis acid-base and Lifshitz-van der Waals components are discussed. Water nucleation and condensation is further explained by surface topography. Tapping mode atomic force microscopy (TMAFM) provides statistical analysis of the topography of these Si-based surfaces. The correlation of the above two characteristics describes the behavior of water condensation at Si-based surfaces. Surface root mean square roughness increasing from several A? to several nm is found to provide nucleation sites that expedite water condensation visibly for silica and silicone. Hydrophilic surfaces have a condensation pattern that forms puddles of water while hydrophobic surfaces form water beads. Polymer adsorption on these surfaces alters the water affinity as well as the surface topography, and therefore controls condensation on Si-based surfaces including silicone intraocular lens (IOL). The polymer film is characterized by Rutherford backscattering spectrometry (RBS) in conjunction with 4.265 MeV 12C(?, ?)12C, 3.045 MeV 16O(?,?)16O nuclear resonance scattering (NRS), and 2.8 MeV elastic recoil detection (ERD) of hydrogen for high resolution composition and areal density measurements. The areal density of hydroxypropyl methylcellulose (HPMC) film ranges from 1018 atom/cm2 to 1019 atom/cm2 gives the silica or silicone surface a roughness of several A? and a wavelength of 0.16+/-0.02 ?m, and prevents fogging by forming a complete wetting layer during water condensation.

Xing, Qian; Herbots, N.; Hart, M.; Bradley, J. D.; Wilkens, B. J.; Sell, D. A.; Sell, Clive H.; Kwong, Henry Mark; Culbertson, R. J.; Whaley, S. D.

2011-06-01

176

Ion Beam Analysis Of Silicon-Based Surfaces And Correlation With Surface Energy Measurements  

SciTech Connect

The water affinity of Si-based surfaces is quantified by contact angle measurement and surface free energy to explain hydrophobic or hydrophilic behavior of silicone, silicates, and silicon surfaces. Surface defects such as dangling bonds, surface free energy including Lewis acid-base and Lifshitz-van der Waals components are discussed. Water nucleation and condensation is further explained by surface topography. Tapping mode atomic force microscopy (TMAFM) provides statistical analysis of the topography of these Si-based surfaces. The correlation of the above two characteristics describes the behavior of water condensation at Si-based surfaces. Surface root mean square roughness increasing from several A ring to several nm is found to provide nucleation sites that expedite water condensation visibly for silica and silicone. Hydrophilic surfaces have a condensation pattern that forms puddles of water while hydrophobic surfaces form water beads. Polymer adsorption on these surfaces alters the water affinity as well as the surface topography, and therefore controls condensation on Si-based surfaces including silicone intraocular lens (IOL). The polymer film is characterized by Rutherford backscattering spectrometry (RBS) in conjunction with 4.265 MeV {sup 12}C({alpha}, {alpha}){sup 12}C, 3.045 MeV {sup 16}O({alpha},{alpha}){sup 16}O nuclear resonance scattering (NRS), and 2.8 MeV elastic recoil detection (ERD) of hydrogen for high resolution composition and areal density measurements. The areal density of hydroxypropyl methylcellulose (HPMC) film ranges from 10{sup 18} atom/cm{sup 2} to 10{sup 19} atom/cm{sup 2} gives the silica or silicone surface a roughness of several A ring and a wavelength of 0.16{+-}0.02 {mu}m, and prevents fogging by forming a complete wetting layer during water condensation.

Xing Qian; Herbots, N.; Hart, M.; Bradley, J. D.; Wilkens, B. J.; Sell, D. A.; Culbertson, R. J.; Whaley, S. D. [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States); Sell, Clive H.; Kwong, Henry Mark Jr. [Associated Retina Consultants, 7600 N 15th Street, Suite 155, Phoenix, AZ 85020 (United States)

2011-06-01

177

Patterned superhydrophobic surface based on Pd-based metallic glass  

NASA Astrophysics Data System (ADS)

Without any modification or post-treatment, superhydrophobic surfaces with good stability were fabricated by hot-embossing honeycomb patterns on Pd40Cu30Ni10P20 bulk metallic glass (BMG). The water contact angle reaches above 150° when the pitch between adjacent cells is larger than the critical size of 115.5 ?m. The wetting behavior on the patterned BMG can be well rationalized in terms of the modified Cassie-Baxter theory [A. B. D. Cassie and S. Baxter, Trans. Faraday Soc. 40, 546 (1944)] by considering surface energy gradient. The achievement of the superhydrophobicity on BMG surface opens a window for the functional applications of metallic glasses.

Xia, Ting; Li, Ning; Wu, Yue; Liu, Lin

2012-08-01

178

Electrostatic painting of nonconductive surfaces with water-base paints  

SciTech Connect

Electrostatic corona painting on nonconductive surfaces normally requires a ground-connected conductive precoating of the surface in order to dissipate the continuously incoming ionic charge from the corona gun. If the surface charge does not flow to ground, the resulting surface electric field will repel a substantial amount of the incoming paint. The authors present a new painting method consisting of generating ultrasonically atomized electrically charged water particles behind the nonconductive surface to be painted. The paint spraying is carried out with a mechanical spray gun maintained at ground potential. The water base paint becomes charged by induction under the influence of the space charge behind the nonconductive surface to be painted. As the resulting charge on the water base paint particles is of opposite polarity to that of the ultrasonically atomized electrically charged water particles cloud, all propelling electric fields converge toward the surface to be painted. The results show excellent transfer efficiencies.

Inculet, I.I. [Univ. of Western Ontario, London, Ontario (Canada). Dept. of Electrical Engineering] [Univ. of Western Ontario, London, Ontario (Canada). Dept. of Electrical Engineering; Klein, R.G. [Nordson Corp., Westlake, OH (United States)] [Nordson Corp., Westlake, OH (United States)

1996-01-01

179

Surface similarity-based molecular query-retrieval  

PubMed Central

Background Discerning the similarity between molecules is a challenging problem in drug discovery as well as in molecular biology. The importance of this problem is due to the fact that the biochemical characteristics of a molecule are closely related to its structure. Therefore molecular similarity is a key notion in investigations targeting exploration of molecular structural space, query-retrieval in molecular databases, and structure-activity modelling. Determining molecular similarity is related to the choice of molecular representation. Currently, representations with high descriptive power and physical relevance like 3D surface-based descriptors are available. Information from such representations is both surface-based and volumetric. However, most techniques for determining molecular similarity tend to focus on idealized 2D graph-based descriptors due to the complexity that accompanies reasoning with more elaborate representations. Results This paper addresses the problem of determining similarity when molecules are described using complex surface-based representations. It proposes an intrinsic, spherical representation that systematically maps points on a molecular surface to points on a standard coordinate system (a sphere). Molecular surface properties such as shape, field strengths, and effects due to field super-positioningcan then be captured as distributions on the surface of the sphere. Surface-based molecular similarity is subsequently determined by computing the similarity of the surface-property distributions using a novel formulation of histogram-intersection. The similarity formulation is not only sensitive to the 3D distribution of the surface properties, but is also highly efficient to compute. Conclusion The proposed method obviates the computationally expensive step of molecular pose-optimisation, can incorporate conformational variations, and facilitates highly efficient determination of similarity by directly comparing molecular surfaces and surface-based properties. Retrieval performance, applications in structure-activity modeling of complex biological properties, and comparisons with existing research and commercial methods demonstrate the validity and effectiveness of the approach.

Singh, Rahul

2007-01-01

180

In vitro analysis of femtosecond laser as an alternative to acid etching for achieving suitable bond strength of brackets to human enamel.  

PubMed

This study aims to evaluate the effect of laser irradiation and orthophosphoric acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel. Three groups (n?=?20) of extracted premolar teeth were randomly established depending on the laser treatment performed on the buccal surfaces: (1) no laser (control); (2) Er:YAG laser (2,940 nm, 0.8 W, 100 ?s/pulse, 10 Hz) and; (3) Ti:Sapphire laser (795 nm, 1 W, 120 fs/pulse, 1 kHz). Each group was divided into two subgroups according to whether 37 %-orthophosphoric acid etching was made after laser irradiation or not. Brackets were randomly luted with Transbond(TM) XT adhesive resin. After 72 h, a SBS test was developed in a universal testing machine (crosshead speed, 0.5 mm/min). Representative specimens from each experimental subgroup were examined by means of scanning electron microscopy. Cement residuals remaining on the premolar surfaces were assessed using the adhesive remnant index. ANOVA, post-hoc tests for intergroup comparisons, chi-square test and linear regression were run for data analyses (??=?0.05). After acid etching, SBS values did not differ regardless the laser treatment. When phosphoric acid was not applied, the SBS values of the femtosecond laser group were significantly higher than for the other groups. Femtosecond laser without acid seems to be the most suitable method to improve bond strengths at the bracket/enamel interface, thus avoiding the disadvantages inherent to acid etching. PMID:23483297

Lorenzo, M C; Portillo, M; Moreno, P; Montero, J; Castillo-Oyagüe, R; García, A; Albaladejo, A

2014-05-01

181

Fluorescence molecular tomography with optimal radon transform based surface reconstruction.  

PubMed

Full angle non-contact fluorescence molecular tomography allows acquiring large data sets from complete angles, and simplifies the experimental setups. Accurately extracting animal surface is important for this kind of imaging systems. However, in in-vivo experiments, mouse breath movements and mechanical errors will influence the surface reconstruction. An optimal radon transform based surface reconstruction method is proposed to handle these two factors. The proposed method uses a line searching method to minimize the mismatch between the reconstructed 3D surface and the projected silhouettes at different angles. Therefore, the proposed method generates the optimal 3D surface compared to other methods based on radon transform. Results show that the mean mismatch of 3D surface generated is less than two CCD pixels (0.154 mm) in in-vivo experiments. In-vivo fluorescence molecular tomography is also performed to demonstrate the efficiency of the proposed method. PMID:19964524

Liu, Xin; Wang, Daifa; Bai, Jing

2009-01-01

182

Deformations of the nondegenerate constant Poisson bracket and antibracket on superspaces of an arbitrary superdimension  

Microsoft Academic Search

We consider (anti-)Poisson superalgebras with a constant nondegenerate (anti)bracket realized on smooth Grassmann-valued functions\\u000a with compact supports in ?n and find the deformations of these superalgebras and their central extensions.

S. E. Konstein; I. V. Tyutin

2008-01-01

183

Deformations of the nondegenerate constant Poisson bracket and antibracket on superspaces of an arbitrary superdimension  

NASA Astrophysics Data System (ADS)

We consider (anti-)Poisson superalgebras with a constant nondegenerate (anti)bracket realized on smooth Grassmann-valued functions with compact supports in ?n and find the deformations of these superalgebras and their central extensions.

Konstein, S. E.; Tyutin, I. V.

2008-04-01

184

Bracketing the Warm Peak Phases of the Middle Pliocene Climate  

Microsoft Academic Search

Estimates of sea surface temperature (SST) from ocean cores reveal a warm phase of the Pliocene between about 3.3 and 3.0 Ma. Pollen records from land-based cores and sections, although not as well-dated, also show evidence for a warmer climate at about the same time. Increased greenhouse forcing and altered ocean heat transports are the leading candidates for the underlying

H. J. Dowsett; M. A. Chandler; G. S. Dwyer; T. M. Cronin

2004-01-01

185

Acoustic emission-based monitoring of surfaces subjected to friction  

NASA Astrophysics Data System (ADS)

Machine parts often contain components which experience relative motion during service. Relative motion between surfaces causes fatigue crack, wear and eventual surface deterioration. Acoustic emission based machinery condition monitoring is a method which can potentially be used to monitor the state of damage present on surfaces during service. This research deals with changes that occur in the characteristics of acoustic emission signals due to altering surface roughness and texture caused by friction loading. A test fixture was used to simulate friction between surfaces of comparable surface finish and obtain acoustic emission signals generated in the process. The different characteristics of signal waveforms obtained at different instances during the test were examined. It was shown that some features like amplitude and duration of the waveforms are sensitive to surface wear.

Asamene, Kassahun; Sundaresan, Mannur

2012-03-01

186

Rough surface scattering based on facet model  

NASA Technical Reports Server (NTRS)

A model for the radar return from bare ground was developed to calculate the radar cross section of bare ground and the effect of the frequency averaging on the reduction of the variance of the return. It is shown that, by assuming that the distribution of the slope to be Gaussian and that the distribution of the length of the facet to be in the form of the positive side of a Gaussian distribution, the results are in good agreement with experimental data collected by an 8- to 18-GHz radar spectrometer system. It is also shown that information on the exact correlation length of the small structure on the ground is not necessary; an effective correlation length may be calculated based on the facet model and the wavelength of the incident wave.

Khamsi, H. R.; Fung, A. K.; Ulaby, F. T.

1974-01-01

187

Small reactor power systems for manned planetary surface bases  

Microsoft Academic Search

A preliminary feasibility study of the potential application of small nuclear reactor space power systems to manned planetary surface base missions was conducted. The purpose of the study was to identify and assess the technology, performance, and safety issues associated with integration of reactor power systems with an evolutionary manned planetary surface exploration scenario. The requirements and characteristics of a

Harvey S. Bloomfield

1987-01-01

188

Surface properties of electrochemically oxidised viscose rayon based carbon fibres  

Microsoft Academic Search

A viscose rayon based activated carbon cloth (ACC) was subjected to electrochemical oxidation under a wide variety of current conditions to modify the surface properties. The changes in the surface properties were physically and chemically characterised. The cation exchange capacity of ACC increased with an increase in the extent of oxidation. The electrochemically oxidised ACC at 1.1A for 6h showed

I. D. Harry; B. Saha; I. W. Cumming

2007-01-01

189

The effect of different porcelain conditioning techniques on shear bond strength of stainless steel brackets.  

PubMed

With the increasing demand for adult orthodontics, a growing need arises to bond attachments to porcelain surfaces. Optimal adhesion to a porcelain surface should allow orthodontic treatment without bond failure but not jeopardize porcelain integrity after debonding. In this study, 90 glazed porcelain facets were divided into three groups according to different conditioning techniques: (1) roughening with a coarse diamond; (2) hydrofluoric acid 8%; (3) microetching with 60 micron aluminum oxide particles. Each group was divided into three groups and stainless steel brackets were then bonded to the conditioned porcelain with three different dental adhesives. The adhesives used were: (1) silane+Right-On; (2) silane+Concise; (3) High-Q-Bond without silane. Four additional facets (three of which conditioned as above and one intact) were analyzed macroscopically and by scanning electron microscopy. Shear bond strength was measured with an Instron universal testing machine and a macroscopic examination of the debonded porcelain surfaces was performed. Results showed that shear bond strength was highly influenced by both conditioning technique and the adhesive. Shear bond strength of the High-Q-Bond groups was significantly lower than both the silane+Right-On and the silane+Concise groups; nevertheless the shear bond strength achieved by High-Q-Bond was enough to sustain full orthodontic treatment duration (except for the group conditioned by roughening with a coarse diamond). Scanning electronic microscopy analysis revealed that diamond roughening and microetching produced only a surface-peeling pattern, whereas hydrofluoric acid conditioning produced an extensive in-depth penetrating pattern. Hydrofluoric acid preparation produced greater shear bond strength than both diamond roughening and microetching. After debonding by means of a shearing force, the percentage of damaged porcelain surfaces in the silane+Concise groups was significantly higher than the silane+Right-On and High-Q-Bond groups. PMID:9790322

Gillis, I; Redlich, M

1998-10-01

190

(p + 1)-Algebra for a super p-brane: the Nambu bracket reformulation  

SciTech Connect

We express the covariant actions of a super p-brane and the corresponding equations of motion, in flat and curved superspaces, in terms of the Nambu (p + 1)-brackets. These brackets make the (p + 1)-algebra structure of a super p-brane manifest. For the flat superspace, this reconstruction of the action also allows reformulating it in terms of two sets of differential forms.

Kamani, D., E-mail: kamani@aut.ac.ir [Amirkabir University of Technology (Tehran Polytechnic), Physics Department (Iran, Islamic Republic of)

2011-05-15

191

Galvanic corrosion between orthodontic wires and brackets in fl uoride mouthwashes  

Microsoft Academic Search

SUMMARY The aim of this investigation was to determine the infl uence of fl uoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution

Nicolas Schiff; Mickaël Boinet; Laurent Morgon; Michèle Lissac; Francis Dalard; Brigitte Grosgogeat

2006-01-01

192

Development of a Physically Based Land Surface Emissivity for TMI  

NASA Astrophysics Data System (ADS)

Over-land precipitation retrieval using active or passive microwave spaceborne measurements requires accurate estimates of the radiometric signature of the surface to constrain the rainfall solutions. Such measurements are a vital part of the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Mission (GPM). For a passive microwave (PMW) radiometer, the radiometric signature is the land surface emissivity, which is characterized by uncertainties introduced by temporal variations of temperature, soil moisture and vegetation water content. Because no such characterization of the surface signature is available at microwave frequencies above L-band, current PMW land rainfall algorithms rely upon scattering-induced signatures at high frequencies (? 85 GHz) and are empirical in nature. Typically, not only is it difficult to quantify the spatial and temporal variability of the surface characteristics that are due to the rain itself, one would also need to know how the surface signature under the rain differs from the signature in neighboring clear areas. Therefore, an improved assessment of the surface emissivities are crucial if one is to make better use of emission-based channels (< 85 GHz) over land for TRMM and future GPM algorithms. In principle, accurate estimates of surface characteristics require accurate knowledge of land surface parameters including surface type, soil moisture and vegetation water content, and the forward modeling to convert land surface parameters to rain-affected surface emissivity. We demonstrate an adaptation of the land surface forward and inverse models that were developed for the AMSR-E and WindSat radiometers, to construct dynamic land surface emissivity datasets for use in physically-based precipitation retrievals over land. TRMM’s long life provides ample data to examine the surface properties under a wide range of environmental conditions, seasons, rain events, etc., and provides the means to examine the variability of the background state under clear and precipitating conditions.

Turk, F. J.; Li, L.; Haddad, Z.

2010-12-01

193

NORTH PORTAL SURFACE - BASED COMPRESSED AIR SYSTEM ANALYSIS  

SciTech Connect

The purpose of this analysis is to capture the design requirements and analyze equipment performance relevant to the Surface-Based Compressed Air System (CAS) design at the Yucca Mountain Site Characterization Project (YMP) Exploratory Studies Facility (ESF).

C.L. Mellen

1995-01-18

194

Surface bond strength in nickel based alloys.  

PubMed

Bonding of ceramic to the alloy is essential for the longevity of porcelain fused to metal restorations. Imported alloys used now a days in processing them are not economical. So this study was conducted to evaluate and compare the bond strength of ceramic material to nickel based cost effective Nonferrous Materials Technology Development Center (NFTDC), Hyderabad and Heraenium S, Heraeus Kulzer alloy. An Instron testing machine, which has three-point loading system for the application of load onto the specimen was utilized for analyzing bond strength of both alloys. Student t test was conducted and t value obtained was 0.644, and the mean value of flexural bond strength of indigenous alloy is 81.75 with standard deviation of 12.25 and of imported alloy is 84.42 with standard deviation of 10.35, indicating that there was no significant difference between the two alloys. Due to ever increasing cost of imported non-precious alloy the need for a cost-effective replacement was fulfilled by indigenous NFTDC alloy. PMID:24431791

Ramesh, Ganesh; Padmanabhan, T V; Ariga, Padma; Joshi, Shalini; Bhuminathan, S; Vijayaraghavan, Vasantha

2013-12-01

195

Comparison of shear bond strengths of ceramic brackets after different time lags between lasing and debonding.  

PubMed

Laser use is effective in the debonding of ceramic brackets. However, a standardization of the laser debonding techniques used has not yet been implemented. The purpose of this study was to evaluate the effect of the time lag elapsed between lasing and shearing on debonding of ceramic brackets. One hundred polycrystalline ceramic brackets were placed on human premolar teeth, which were randomly divided into five groups of 20. One group was assigned as the control. The Er-YAG laser was applied on each bracket in four experimental groups at 5 W for 6 s with the scanning method. Debonding was performed 1 s, 18 s, 30 s, or 60 s after laser exposure. Shear bond strengths and adhesive remnant index scores were measured. Statistically significant difference was observed between the control and experimental groups when the data for the shear bond strengths was considered (p < 0.05). Adhesive remnant index scores of the groups were not statistically different (p > 0.05). Debonding ceramic brackets after 18 s when lased 6 s using an Er-YAG laser with the scanning method is safe and also suitable for clinical use since three brackets can be debonded at a time in succession. PMID:22076589

Tozlu, Murat; Oztoprak, Mehmet Oguz; Arun, Tülin

2012-11-01

196

Surface classification and detection of latent fingerprints based on 3D surface texture parameters  

NASA Astrophysics Data System (ADS)

In the field of latent fingerprint detection in crime scene forensics the classification of surfaces has importance. A new method for the scientific analysis of image based information for forensic science was investigated in the last years. Our image acquisition based on a sensor using Chromatic White Light (CWL) with a lateral resolution up to 2 ?m. The used FRT-MicroProf 200 CWL 600 measurement device is able to capture high-resolution intensity and topography images in an optical and contact-less way. In prior work, we have suggested to use 2D surface texture parameters to classify various materials, which was a novel approach in the field of criminalistic forensic using knowledge from surface appearance and a chromatic white light sensor. A meaningful and useful classification of different crime scene specific surfaces is not existent. In this work, we want to extend such considerations by the usage of fourteen 3D surface parameters, called 'Birmingham 14'. In our experiment we define these surface texture parameters and use them to classify ten different materials in this test set-up and create specific material classes. Further it is shown in first experiments, that some surface texture parameters are sensitive to separate fingerprints from carrier surfaces. So far, the use of surface roughness is mainly known within the framework of material quality control. The analysis and classification of the captured 3D-topography images from crime scenes is important for the adaptive preprocessing depending on the surface texture. The adaptive preprocessing in dependency of surface classification is necessary for precise detection because of the wide variety of surface textures. We perform a preliminary study in usage of these 3D surface texture parameters as feature for the fingerprint detection. In combination with a reference sample we show that surface texture parameters can be an indication for a fingerprint and can be a feature in latent fingerprint detection.

Gruhn, Stefan; Fischer, Robert; Vielhauer, Claus

2012-05-01

197

Effect of moisture, saliva, and blood contamination on the shear bond strength of brackets bonded with a conventional bonding system and self-etched bonding system  

PubMed Central

Background: The success of bonding brackets to enamel with resin bonding systems is negatively affected by contamination with oral fluids such as blood and saliva. The new self-etch primer systems combine conditioning and priming agents into a single application, making the procedure more cost effective. Objective: The purpose of the study was to investigate the effect of moisture, saliva and blood contamination on shear bond strength of orthodontic brackets bonded with conventional bonding system and self-etch bonding system. Materials and Methods: Each system was examined under four enamel surface conditions (dry, water, saliva, and blood), and 80 human teeth were divided into two groups with four subgroups each of 10 according to enamel surface condition. Group 1 used conventional bonding system and Group 2 used self-etched bonding system. Subgroups 1a and 2a under dry enamel surface conditions; Subgroups 1b and 2b under moist enamel surface condition; Subgroups 3a and 3b under saliva enamel surface condition and Subgroup 4a and 4b under blood enamel surface condition. Brackets were bonded, and all the samples were then submitted to a shear bond test with a universal testing machine with a cross head speed of 1mm/sec. Results: The results showed that the contamination reduced the shear bond strength of all groups. In self-etch bonding system water and saliva had significantly higher bond strength when compared to other groups. Conclusion: It was concluded that the blood contamination showed lowest bond strength from both bonding systems. Self-etch bonding system resulted in higher bond strength than conventional bonding system under all conditions except the dry enamel surface.

Prasad, Mandava; Mohamed, Shamil; Nayak, Krishna; Shetty, Sharath Kumar; Talapaneni, Ashok Kumar

2014-01-01

198

Engineered surface Bloch waves in graphene-based hyperbolic metamaterials.  

PubMed

A kind of tunable hyperbolic metamaterial (HMM) based on the graphene-dielectric layered structure at near-infrared frequencies is presented, and the engineered surface Bloch waves between graphene-based HMM and isotropic medium are investigated. Our calculations demonstrate that the frequency and frequency range of surface Bloch waves existence can be tuned by varying the Fermi energy of graphene sheets via electrostatic biasing. Moreover, we show that the frequency range of surface Bloch waves existence can be broadened by decreasing the thickness of the dielectric in the graphene-dielectric layered structure or by increasing the layer number of graphene sheets. PMID:24663596

Xiang, Yuanjiang; Guo, Jun; Dai, Xiaoyu; Wen, Shuangchun; Tang, Dingyuan

2014-02-10

199

Isotherms of surface tension in copper-based systems  

NASA Astrophysics Data System (ADS)

The surface tensions of pure copper and its alloys with antimony, tin, and indium have been measured for free surfaces and grain boundaries. The measurements have been conducted at 1000°C in a hydrogen atmosphere by the zero-creep method in combination with the thermal-grooving method. The surface-tension isotherms satisfy the Szyszkowski’s equation. Based on the data obtained, the values of adsorptive capacity of free surface and grain boundaries ( z FS and z GB), constants of adsorption equilibrium ( b FS and b GB), occupancies (fraction of occupied sites ?), and free energies of binding of impurity atoms with the surface (? F) have been calculated. All these parameters for copper alloys with Sb, Sn, and In within their solid solutions as well as for alloys with Sb, Bi, and Au at other temperatures based on the data obtained by the other authors have been compared.

Zhevnenko, S. N.

2008-09-01

200

In vivo bracket bond strength using two adhesive systems applied under wet and dry conditions.  

PubMed

The purpose of this study was to investigate, in vivo, the bond strength of two adhesive materials: a moisture insensitive primer (MIP)* and a one step self etching primer (SEP)*, both used with Transbond XT* on dry and wet enamel and an adhesion time of 10-15 minutes. First or second upper and/or lower bicuspids (n = 124), to be extracted for orthodontic reasons, were used. A comparison of the materials' behavior was conducted under four different situations: 1) MIP on enamel etched and dry; 2) MIP on a surface etched and wetted with patient's saliva; 3) SEP on a dry field, 4) SEP on a saliva-wet enamel. For statistical analysis, Dunn-Sidak's multiple comparison test was applied with a probability of less than 0.05 (before correction). Stainless steel brackets with mesh-backed pads were bonded to the teeth. Bond strength was tested with modified orthodontic pliers on which a strain-gage was fixed to measure handle deformation while debonding. Moisture insensitive primer tested on wet enamel showed the highest mean bond strength outcomes (8.98 MPa) compared to one step etching primer (5.81 MPa). Statistical difference between these groups was significant (p = 0.000). Standard deviation was lower for the one-step technique, under dry and wet conditions. Since the media bond strength of SEP proved sufficient for clinical purposes and its behavior tended to be more homogeneous, this was considered the best choice. PMID:17121197

Ciola, Elida N; Picco, Alicia M; Sois, Ana M; Lucena, Mercedes H; Alonso, Verónica; Valvo, Maela; García, Luis; Geazzi, Ariel

2006-01-01

201

Mechanically robust superhydrophobic polymer surfaces based on protective micropillars.  

PubMed

Considerable attention is currently being devoted less to the question of whether it is possible to produce superhydrophobic polymer surfaces than to just how robust they can be made. The present study demonstrates a new route for improving the mechanical durability of water-repellent structured surfaces. The key idea is the protection of fragile fine-scale surface topographies against wear by larger scale sacrificial micropillars. A variety of surface patterns was manufactured on polypropylene using a microstructuring technique and injection molding. The surfaces subjected to mechanical pressure and abrasive wear were characterized by water contact and sliding angle measurements as well as by scanning electron microscopy and roughness analysis based on optical profilometry. The superhydrophobic polypropylene surfaces with protective structures were found to maintain their wetting properties in mechanical compression up to 20 MPa and in abrasive wear tests up to 120 kPa. For durable properties, the optimal surface density of the protective pillars was found to be about 15%. The present approach to the production of water-repellent polymer surfaces provides the advantages of mass production and mechanical robustness with practical applications of structurally functionalized surfaces. PMID:24483340

Huovinen, Eero; Takkunen, Laura; Korpela, Tarmo; Suvanto, Mika; Pakkanen, Tuula T; Pakkanen, Tapani A

2014-02-11

202

Shear bond strength comparison between direct and indirect bonded orthodontic brackets.  

PubMed

The purpose of this study was to compare the shear bond strength of orthodontic brackets bonded to teeth with either an indirect bonding technique and a new adhesive resin or a direct bonding technique and a light-activated adhesive. Fifty-four extracted premolars were mounted in acrylic blocks and randomly divided into 2 groups (n = 27). In one group, orthodontic brackets were bonded to premolars with an indirect bonding adhesive system; in the other, brackets were bonded with the direct method. Seventy-two hours later, the brackets were placed in a testing machine and subjected to a shear force with a crosshead speed of 1 mm/minute. The mean shear bond strengths for the indirect and direct groups were 11.2 and 10.9 MPa, respectively, both exceeding the minimum shear bond strength range of 5.9 to 7.8 MPa often cited in the literature for clinical success. Data were analyzed with Student t tests. No significant difference in shear bond strength between the 2 groups was detected (P =.76). Resin remnants on orthodontic bracket pads were observed with a dissecting microscope at 30x magnification and scored with a modified adhesive remnant index. There was no significant difference between groups (P >.05). There was also no correlation between shear bond strength and the percentage of adhesive resin remnants left on the orthodontic bracket. Under the conditions of this study, no evidence suggests a difference in shear bond strength of orthodontic brackets bonded to tooth enamel, whether they are bonded with the direct or indirect technique. PMID:14614426

Yi, Gia K; Dunn, William J; Taloumis, Louis J

2003-11-01

203

Contour-Based Surface Reconstruction using MPU Implicit Models  

PubMed Central

This paper presents a technique for creating a smooth, closed surface from a set of 2D contours, which have been extracted from a 3D scan. The technique interprets the pixels that make up the contours as points in ?3 and employs Multi-level Partition of Unity (MPU) implicit models to create a surface that approximately fits to the 3D points. Since MPU implicit models additionally require surface normal information at each point, an algorithm that estimates normals from the contour data is also described. Contour data frequently contains noise from the scanning and delineation process. MPU implicit models provide a superior approach to the problem of contour-based surface reconstruction, especially in the presence of noise, because they are based on adaptive implicit functions that locally approximate the points within a controllable error bound. We demonstrate the effectiveness of our technique with a number of example datasets, providing images and error statistics generated from our results.

Braude, Ilya; Marker, Jeffrey; Museth, Ken; Nissanov, Jonathan; Breen, David

2007-01-01

204

A pyramidal data structure for triangle-based surface description  

Microsoft Academic Search

A hierarchical model for approximating 2-1\\/2-dimensional surfaces is described. This model, called a Delaunay pyramid, is a method for compression of spatial data and representation of a surface at successively finer levels of detail. A Delaunay pyramid is based on a sequence of Delaunay triangulations of suitably defined subsets of the set of data points. A triangle-oriented encoding structure for

Leila De Floriani

1989-01-01

205

Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach.  

PubMed

In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers. PMID:23572003

Andryieuski, Andrei; Lavrinenko, Andrei V

2013-04-01

206

Local functional descriptors for surface comparison based binding prediction  

PubMed Central

Background Molecular recognition in proteins occurs due to appropriate arrangements of physical, chemical, and geometric properties of an atomic surface. Similar surface regions should create similar binding interfaces. Effective methods for comparing surface regions can be used in identifying similar regions, and to predict interactions without regard to the underlying structural scaffold that creates the surface. Results We present a new descriptor for protein functional surfaces and algorithms for using these descriptors to compare protein surface regions to identify ligand binding interfaces. Our approach uses descriptors of local regions of the surface, and assembles collections of matches to compare larger regions. Our approach uses a variety of physical, chemical, and geometric properties, adaptively weighting these properties as appropriate for different regions of the interface. Our approach builds a classifier based on a training corpus of examples of binding sites of the target ligand. The constructed classifiers can be applied to a query protein providing a probability for each position on the protein that the position is part of a binding interface. We demonstrate the effectiveness of the approach on a number of benchmarks, demonstrating performance that is comparable to the state-of-the-art, with an approach with more generality than these prior methods. Conclusions Local functional descriptors offer a new method for protein surface comparison that is sufficiently flexible to serve in a variety of applications.

2012-01-01

207

Wavelet-based detection of clods on a soil surface  

NASA Astrophysics Data System (ADS)

One of the aims of the tillage operation is to produce a specific range of clod sizes, suitable for plant emergence. Due to its cloddy structure, a tilled soil surface has its own roughness, which is connected also with soil water content and erosion phenomena. The comprehension and modeling of surface runoff and erosion require that the micro-topography of the soil surface is well estimated. Therefore, the present paper focuses on the soil surface analysis and characterization. An original method consisting in detecting the individual clods or large aggregates on a 3D digital elevation model (DEM) of the soil surface is introduced. A multiresolution decomposition of the surface is performed by wavelet transform. Then a supervised local maxima extraction is performed on the different sub surfaces and a last process makes the validation of the extractions and the merging of the different scales. The method of detection was evaluated with the help of a soil scientist on a controlled surface made in the laboratory as well as on real seedbed and ploughed surfaces, made by tillage operations in an agricultural field. The identifications of the clods are in good agreement, with an overall sensitivity of 84% and a specificity of 94%. The false positive or false negative detections may have several causes. Some very nearby clods may have been smoothed together in the approximation process. Other clods may be embedded into another peace of the surface relief such as another bigger clod or a part of the furrow. At last, the low levels of decomposition are dependent on the resolution and the measurement noise of the DEM. Therefore, some borders of clods may be difficult to determine. The wavelet-based detection method seems to be suitable for soil surfaces described by 2 or 3 levels of approximation such as seedbeds.

Vannier, E.; Ciarletti, V.; Darboux, F.

2009-11-01

208

The Effects of Prophylactic Ozone Pretreatment of Enamel on Shear Bond Strength of Orthodontic Brackets Bonded with Total or Self-Etch Adhesive Systems  

PubMed Central

Objectives: The aim of this in vitro study is to determine (1) shear bond strength (SBS) of brackets bonded with self-etch and total-etch adhesive after ozone treatment (2) bond failure interface using a modified Adhesive Remnant Index (ARI). Methods: 52 premolars were randomly assigned into four groups (n=13) and received the following treatments: Group 1: 30 s Ozone (Biozonix, Ozonytron, Vehos Medikal, Ankara, Turkey) application + Transbond Plus Self-Etching Primer (SEP) (3M) + Transbond XT (3M), Group 2: Transbond Plus SEP + Transbond XT, Group 3: 30 s Ozone application + 37% orthophosphoric acid + Transbond XT Primer (3M) + Transbond XT, Group 4: 37% orthophosphoric acid + Transbond XT Primer + Transbond XT. All samples were stored in deionised water at 37°C for 24 hours. Shear debonding test was performed by applying a vertical force to the base of the bracket at a cross-head speed of 1 mm/min. Results: The mean SBS results were Group 1: 10.48 MPa; Group 2: 8.89 MPa; Group 3: 9.41 MPa; Group 4: 9.82 MPa. One-Way Variance Test revealed that the difference between the groups was not statistically significant (P=0.267). Debonded brackets were examined by an optical microscope at X16 magnification to determine the bond failure interface using a modified ARI. The results were (mean) Group 1: 2.38; Group 2: 1.31; Group 3: 3.00; Group 4: 1.92. Multiple comparisons showed that Groups 1 and 2, 2 and 3, 3 and 4 were statistically different (P=0.014, P<.001 and P=0.025). Conclusions: Ozone treatment prior to bracket bonding does not affect the shear bond strength.

Cehreli, Sevi Burcak; Guzey, Asli; Arhun, Neslihan; Cetinsahin, Alev; Unver, Bahtiyar

2010-01-01

209

The Effect on Final Bond Strength of Bracket Manipulation Subsequent To Initial Positioning  

NASA Astrophysics Data System (ADS)

The shear bond strength of light activated orthodontic adhesives varies according to the composition of the material, placement protocol, and time prior to light curing. Manipulating brackets after their initial placement on a tooth can disrupt the adhesive's polymerization and compromise final bond strength. No previous research has investigated how a specific degree of manipulation, and the amount of time elapsed prior to curing, under specific lighting conditions, affects the orthodontic adhesives shear bond strength. Victory SeriesRTM, MBT prescription, premolar (3M Unitek, Monrovia, CA) orthodontic brackets were bonded using three different adhesives to sixty (60) bicuspids and varying the time after bracket manipulation before curing. The shear bond strength was calculated for each specimen. The brackets were debonded and the same teeth were rebonded with new, identical brackets, using the same protocol and under the same conditions. The results showed a statistically significant difference between the shear bond strength of Transbond XT and Grengloo, with Transbond XT having the highest strength. There was also a statistically significance difference in bond strength between the group cured 30 seconds after manipulation and the groups manipulated at different intervals prior to curing, with the 30 second group having the highest bond strength. This study confirms that various orthodontic adhesives have different bond strengths depending on manipulation and varying times prior to curing each adhesive.

Beebe, David A.

210

Wavelet frame based surface reconstruction from unorganized points  

NASA Astrophysics Data System (ADS)

Applications of wavelet frames to image restoration problems (e.g. image deblurring and inpainting) have been successful due to their redundancy and capability of sparsely approximating piecewise smooth functions like images (see e.g. [13,14,8]). However, wavelet frames have not yet been used for surface reconstruction problems. Recently in [6], connections between one of the wavelet frame based image restoration model [8,28,48] and variational models (e.g. the ROF model [45]) were rigorously established. Such connections not only grant new insights to wavelet frame based image restorations, it also case a geometric explanation to wavelet frame based approaches. This leads us to a wavelet frame based model, as well as a fast algorithm, to reconstruct implicit surfaces from unorganized point sets in R3. We will demonstrate the effectiveness of the proposed model using several commonly used examples.

Dong, Bin; Shen, Zuowei

2011-09-01

211

Novel Micrometeorological Surface Parameterization Using Physically Based Scaling Variables  

NASA Astrophysics Data System (ADS)

Surface parameterizations based on novel scaling parameters were developed, tested in a field experiment, and compared to the Monin-Obuhov similarity theory. Dimensionless wind shears based on the standard deviation of the turbulent vertical velocity, and a turbulent kinetic energy defined velocity scale, FMsw and FMuTKE respectively, are better at characterizing the stable regime and are far better for the strongly unstable conditions than the conventionally defined dimensionless wind shear based on the friction velocity, FMu* . This establishes that direct turbulent velocity measures, rather than the momentum-flux based friction velocity, are superior scaling variables for surface layer dimensional analyses. The same scaling velocities were applied to the dimensionless temperature profile but due to experimental errors in temperature gradient measurements the relationships between them couldn't be examined. Richardson numbers, whether defined conventionally or on new scaling variables, were also not reliable because of the large experimental errors in the temperature profile measurements.

Stephens, Jilmarie

212

Reusable localized surface plasmon sensors based on ultrastable nanostructures.  

PubMed

Nanoparticle arrays created by nanosphere lithography are widely used in sensing applications since their localized surface plasmon resonances are extremely sensitive to changes in the local dielectric environment. A major drawback for any biologically oriented sensing application of conventionally produced particle arrays is the lack of stability of the nanoparticles in aqueous media and buffer solutions. Here, a robust and reusable nanoscale sensing platform based on localized surface plasmon resonances of gold nanoparticles embedded in a silicon dioxide matrix is presented. The architecture exhibits extremely high stability in aqueous environments and can be regenerated several times by simple mechanical cleaning of the surface. The platforms surface is ultraflat by design, thus making it an ideal substrate for any bio-oriented sensing application. PMID:19899088

Vogel, Nicolas; Jung, Mathieu; Bocchio, Noelia L; Retsch, Markus; Kreiter, Maximilian; Köper, Ingo

2010-01-01

213

The effect of clusters on surface based transport modeling  

NASA Astrophysics Data System (ADS)

Clusters are common bedforms that develop as part of the surface structure of gravel and sand channels. Surface grains may re-arrange during a receding flood flow or a sustained low flow such that the larger size fractions group into clusters of two or more grains. These clusters can increase the sheltering effect of the large grains and also the shear stress necessary to mobilize fine sediment sizes. Transport models, both surface and subsurface beds, continue to show scatter when compared to observed transport data. Residuals, the ratio of predicted to measured transport value, remain even when the transport model accounts for the coarser surface sediments through adjustment of the hiding factor. This work examines whether clusters may be responsible for some of the mismatch between predicted and observed transport rates. The Wilcock and Crowe Surface Based Transport Model has been used to predict the transport from beds for which fractional transport data were available. Residuals were then examined against channel bed surface structure. Data from the flume runs used to develop the SBTM were analyzed and clusters were identified from photographs of the channel bed surfaces. Specific residuals were then analyzed for corresponding cluster presence. This analysis provides a first estimate of how the presence of clusters can cause predicted transport rates to deviate from observation.

Curran, Joanna C.; Ockelford, Annie

2013-04-01

214

Bases on multipunctured Riemann surfaces and interacting strings amplitudes  

Microsoft Academic Search

The Krichever-Novikov bases are studied on Riemann surfaces with more-than-two punctures. The bases are presented and the completness theorem is proven for the case of integer (up to a common constant) momenta. Then the interacting strings are considered, the amplitudes and partition functions are obtained, comparable with that of path-integral approach. For the amplitudes the simple geometric implication is proposed.

V. A. Sadov; Moscow V

1991-01-01

215

Ab initio based multiscale modeling of alloy surface segregation.  

PubMed

A fully integrated ab initio based multiscale model for analysis of segregation at alloy surfaces is presented. Major components of the model include a structure-energy analysis from the first-principles density functional theory (DFT), a Monte Carlo/molecular dynamics (MC/MD) hybrid simulation scheme for atomic transport, and a reactive force field formalism that binds the two. The multiscale model accurately describes the atomic transport processes in a multi-component alloy system at finite temperature, and is capable of providing quantitative predictions for surface compositions. The validity of the model was demonstrated by investigating the temperature-dependent segregation behavior of B2 FeAl binary alloy surfaces with a detailed description of the segregation mechanism. Based on the model's prediction capabilities, potential extension of the model to the analysis of systems undergoing rapid chemical reactions is discussed. PMID:23114706

Kwak, Hyunwook; Shin, Yun Kyung; van Duin, Adri C T; Vasenkov, Alex V

2012-12-01

216

Two simple designs for surface-plasmon-resonance-based sensing  

Microsoft Academic Search

Surface plasmon resonance spectroscopy is becoming an increasingly important technique in biotechnology and chemical sensing. We present two simple, low cost, high sensitivity devices. The first is laser based mechanical implementation of a Kretschmann setup. Angle sweep is realized in two stages: step motor is used for coarse angle setting, and continuous angle sweep is achieved with a mirror on

Andrea Kobe; Janez I. Mozina

1999-01-01

217

Improving light-based geolocation by including sea surface temperature  

Microsoft Academic Search

An approach to integrate sea surface temperature (SST) measurements into estimates of geolocations calculated by changes in ambient light level from data downloaded from pop-up satellite archival tags (PSAT) is presented. The model is an extension of an approach based on Kalman filter estimation in a state-space model. The approach uses longitude and latitude estimated from light, and SST. The

Anders Nielsen; Keith A. Bigelow

2005-01-01

218

Improving light-based geolocation by including sea surface temperature  

Microsoft Academic Search

An approach to integrate sea surface temperature (SST) measurements into estimates of geolocations calculated by changes in ambient light level from data downloaded from pop-up satellite archival tags (PSAT) is presented. The model is an extension of an approach based on Kalman filter estimation in a state- space model. The approach uses longitude and latitude estimated from light, and SST.

ANDERS NIELSEN; KEITH A. BIGELOW; MICHAEL K. MUSYL; JOHN R. SIBERT

2006-01-01

219

Control of myoelectric prosthetic hand based on surface EMG  

Microsoft Academic Search

In this paper, a robot hand with two fingers, thumb and index finger, aiming at application to a myoelectric prosthetic hand was built to implement fundamental motions, such as grasping and holding, required in daily life. In order to control each finger of the developed robot hand independently, an identifier which recognizes the finger motions based on the surface EMG

Chiharu Ishii; Akitoshi Harada; Takashi Nakakuki; Hiroshi Hashimoto

2011-01-01

220

The circular polarization interferometer based surface plasmon biosensor  

Microsoft Academic Search

Circular polarization interferometry configuration was used to develop surface plasmon based instrument, which had two light beams with p- and s- polarization states individually within the common path. We used evanescent field to determine the concentration of the biological sample via varying incident angles enabled phase interrogation. The instrument named \\

C.-M. Jan; Y.-H. Lee; C.-K. Lee

2010-01-01

221

Deformations of Poisson brackets and extensions of Lie algebras of contact vector fields  

NASA Astrophysics Data System (ADS)

CONTENTSIntroduction § 1. Main theoremsChapter I. Algebra § 2. Moyal deformations of the Poisson bracket and *-product on \\mathbb R^{2n} § 3. Algebraic construction § 4. Central extensions § 5. ExamplesChapter II. Deformations of the Poisson bracket and *-product on an arbitrary symplectic manifold § 6. Formal deformations: definitions § 7. Graded Lie algebras as a means of describing deformations § 8. Cohomology computations and their consequences § 9. Existence of a *-productChapter III. Extensions of the Lie algebra of contact vector fields on an arbitrary contact manifold §10. Lagrange bracket §11. Extensions and modules of tensor fieldsAppendix 1. Extensions of the Lie algebra of differential operatorsAppendix 2. Examples of equations of Korteweg-de Vries typeReferences

Ovsienko, V.; Roger, C.

1992-12-01

222

Response mechanism for surface acoustic wave gas sensors based on surface-adsorption.  

PubMed

A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data. PMID:24743157

Liu, Jiansheng; Lu, Yanyan

2014-01-01

223

Response Mechanism for Surface Acoustic Wave Gas Sensors Based on Surface-Adsorption  

PubMed Central

A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data.

Liu, Jiansheng; Lu, Yanyan

2014-01-01

224

A combined voxel and surface based method for topology correction of brain surfaces  

NASA Astrophysics Data System (ADS)

Brain surfaces provide a reliable representation for cortical mapping. The construction of correct surfaces from magnetic resonance images (MRI) segmentation is a challenging task, especially when genus zero surfaces are required for further processing such as parameterization, partial inflation and registration. The generation of such surfaces has been approached either by correcting a binary image as part of the segmentation pipeline or by modifying the mesh representing the surface. During this task, the preservation of the structure may be compromised because of the convoluted nature of the brain and noisy/imperfect segmentations. In this paper, we propose a combined, voxel and surfacebased, topology correction method which preserves the structure of the brain while yielding genus zero surfaces. The topology of the binary segmentation is first corrected using a set of topology preserving operators applied sequentially. This results in a white matter/gray matter binary set with correct sulci delineation, homotopic to a filled sphere. Using the corrected segmentation, a marching cubes mesh is then generated and the tunnels and handles resulting from the meshing are finally removed with an algorithm based on the detection of nonseparating loops. The approach was validated using 20 young individuals MRI from the OASIS database, acquired at two different time-points. Reproducibility and robustness were evaluated using global and local criteria such as surface area, curvature and point to point distance. Results demonstrated the method capability to produce genus zero meshes while preserving geometry, two fundamental properties for reliable and accurate cortical mapping and further clinical studies.

Gris, Florence; Favreau, Jean-Marie; Acosta, Oscar; Barra, Vincent; Salvado, Olivier

2010-03-01

225

Photonic Crystal Biosensor Based on Optical Surface Waves  

PubMed Central

A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS/PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately.

Konopsky, Valery N.; Karakouz, Tanya; Alieva, Elena V.; Vicario, Chiara; Sekatskii, Sergey K.; Dietler, Giovanni

2013-01-01

226

A physically based model of global freshwater surface temperature  

NASA Astrophysics Data System (ADS)

Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5° on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for the Arctic rivers because the timing of ice breakup is predicted too late in the year due to the lack of including a mechanical breakup mechanism. Moreover, surface water temperatures for tropical rivers were overestimated, most likely due to an overestimation of rainfall temperature and incoming shortwave radiation. The spatiotemporal variation of water temperature reveals large temperature differences between water and atmosphere for the higher latitudes, while considerable lateral transport of heat can be observed for rivers crossing hydroclimatic zones, such as the Nile, the Mississippi, and the large rivers flowing to the Arctic. Overall, our model results show promise for future projection of global surface freshwater temperature under global change.

Beek, Ludovicus P. H.; Eikelboom, Tessa; Vliet, Michelle T. H.; Bierkens, Marc F. P.

2012-09-01

227

Finite element analysis and optimal design of the mudsill and bracket of large-scale bag filter  

Microsoft Academic Search

By using the finite element analysis software ANSYS, the model of the mudsill and bracket of large-scale bag filter was established, and the stress distribution and deformation of the structure were analyzed. Then under the prerequisite of the mudsill and bracket structure satisfied in possessing enough strength and stiffness and taking the mass of the structure to be the lightest

Wang Shijie; Zhang Zhichen; Liao Shanmei; Zhang Lei; Lv Guosheng; Liu Linzhi

2010-01-01

228

Hyperspherical/Oscillator Brackets and Symmetrized States: A Simple Algorithm for A > 3 Few-Body Calculations  

NASA Astrophysics Data System (ADS)

A simple universal algorithm for the construction of symmetrized states of hyperspherical harmonics/oscillator functions and for the calculation of transformation brackets between their different sets is proposed and tested. In a A > 3 case it allows practical calculations for high excitations. Various matrix elements can be effectively computed using the brackets obtained.

Efros, V. D.

1995-11-01

229

Enamel loss and adhesive remnants following bracket removal and various clean-up procedures in vitro.  

PubMed

This study evaluated the enamel loss and composite remnants after debonding and clean-up. The tested null hypothesis is that there are no differences between different polishing systems regarding removing composite remnants without damaging the tooth surface. Brackets were bonded to 75 extracted human molars and removed after a storage period of 100 hours. The adhesive remnant index (ARI) was evaluated. The clean-up was carried out with five different procedures: 1. carbide bur; 2. carbide bur and Brownie and Greenie silicone polishers; 3. carbide bur and Astropol polishers; 4. carbide bur and Renew polishers; and 5. carbide bur, Brownie, Greenie and PoGo polishers. Silicone impressions were made at baseline (T0) and after debonding (T1) and polishing (T2) to produce plaster replicas. The replicas were analysed with a three-dimensional laser scanner and measured with analytical software. Statistical analysis was performed with the Kruskal-Wallis test and pairwise Wilcoxon tests with Bonferroni-Holm adjustment (? = 0.05). Enamel breakouts after debonding were detectable in 27 per cent of all cases, with a mean volume loss of 0.02 mm(3) (±0.03 mm(3)) and depth of 44.9 ?m (±48.3 ?m). The overall ARI scores was 3 with a few scores of 1 and 2. The composite remnants after debonding had a mean volume of 2.48 mm(3) (±0.92 mm(3)). Mean volume loss due to polishing was 0.05 mm(3) (±0.26 mm(3)) and the composite remnants had a mean volume of 0.22 mm(3) (±0.32 mm(3)). There were no statistically significant differences in volumetric changes after polishing (P?=?0.054) between the different clean-up methods. However, sufficient clean-up without enamel loss was difficult to achieve. PMID:21228118

Ryf, Sacha; Flury, Simon; Palaniappan, Senthamaraiselvi; Lussi, Adrian; van Meerbeek, Bart; Zimmerli, Brigitte

2012-02-01

230

Torque Stability of Plastic Brackets Following Multiple Loading and Artificial Material Aging – an In-Vitro Comparison  

Microsoft Academic Search

\\u000a Abstract\\u000a \\u000a \\u000a Objective:\\u000a   The objective of this study was to compare the loaddeflection\\u000a behavior of plastic brackets made of various materials in\\u000a response to repeated torque loads with each other and with steel\\u000a brackets. Material fatigue during wire’s play in the bracket slot, the\\u000a brackets’ elasticity and the torsional forces applied were analyzed.\\u000a \\u000a \\u000a \\u000a \\u000a Material and Methods:\\u000a   Groups of ten brackets, each

Matthias Möller; Arndt Klocke; Reza Sadat-Khonsari; Volker Schlegel; Bärbel Kahl-Nieke

2009-01-01

231

Surface-based passive microwave studies of multiyear sea ice  

NASA Technical Reports Server (NTRS)

Results are presented on surface-based multifrequency passive microwave observations of multiyear (MY) sea ice in the eastern Arctic Basin, the Beaufort Sea, the Canadian archipelago, and the northern Greenland Sea. The analyses of these data show that the magnitude of the spectral gradient of emissivity is directly related to the existence and the thickness of a decomposed surface ice layer with very high porosity. Spectra for melt ponds with a frozen surface layer closely resembled those of lake ice and showed a positive spectral gradient. The variance among emissivity spectra for MY ice was caused primarily by the distributions of melt ponds and by the presence of significant amounts of scattering inhomogeneities in the snow and the upper 20-30-cm layer of the ice.

Grenfell, T. C.

1992-01-01

232

3D reconstruction of surface based on binocular vision  

NASA Astrophysics Data System (ADS)

This paper proposes a feasible program of 3D curve surface reconstruction based on the method of binocular stereo vision system which is composed of two industrial CCD cameras. On the basis of bipolar linear constraints, the method gets information modules to match the 3D curve surface feature at sub-pixel level by the sift algorithm so that the reconstruction of 3D stereo structure can be realized. Then, through the combination of the acquired feature vectors with 2D image to affine the curve surface, the feature extraction and the recognition progress can be realized by iteration. Finally, a 3D depth map can be produced. This method can help improve the robustness of the stereo matching and get a better 3D reconstruction in a simple way with low cost.

Hu, Xiaoping; Peng, Tao; Xie, Ke

2013-10-01

233

Optical Triangulation-Based Microtopographic Inspection of Surfaces  

PubMed Central

The non-invasive inspection of surfaces is a major issue in a wide variety of industries and research laboratories. The vast and increasing range of surface types, tolerance requirements and measurement constraints demanded during the last decades represents a major research effort in the development of new methods, systems and metrological strategies. The discreet dimensional evaluation the rugometric characterization and the profilometric inspection seem to be insufficient in many instances. The full microtopographic inspection has became a common requirement. Among the different systems developed, optical methods have the most important role and among those triangulation-based ones have gained a major status thanks to their flexibility, reliability and robustness. In this communication we will provide a brief historical review on the development of optical triangulation application to the dimensional inspection of objects and surfaces and on the work done at the Microtopography Laboratory of the Physics Department of the University of Minho, Portugal, in the development of methods and systems of optical triangulation-based microtopographic inspection of surfaces.

Costa, Manuel F. M.

2012-01-01

234

A block-based landslide model using smooth surface reconstructions  

NASA Astrophysics Data System (ADS)

The present work is combining the block-based landslide-model developed by Tinti and Bertolucci (2000) with different smooth surface reconstruction methods. This enables us to directly solve the underlying ODE-system, that is describing the blocks motion, numerically. The numerical model is based on the idea that the sliding mass can be discretized by a certain number of quadrilateral blocks of finite volume, where the movement of the single blocks is described using a Lagrangian approach. Within this approach, the underlying equations of motion require for each time-step the computation of the acceleration of each of the blocks from their position on the sliding surface, where information on its curvature is needed in order to compute the centripetal component. To come up to this, different methods were used to interpolate smooth, two times differentiable, surface reconstructions from a given number of points that are describing the real sliding surface. The numerical solution of the model in time is obtained using higher-order explicit and implicit time-integration methods The results of the simulations are evaluated especially with respect to the arrival times and final velocities of the sliding mass and therefore a possible tsunamigenic impact.

Elsen, Katharina; Tinti, Stefano

2014-05-01

235

Lunar base surface mission operations. Lunar Base Systems Study (LBSS) task 4.1  

NASA Technical Reports Server (NTRS)

The purpose was to perform an analysis of the surface operations associated with a human-tended lunar base. Specifically, the study defined surface elements and developed mission manifests for a selected base scenario, determined the nature of surface operations associated with this scenario, generated a preliminary crew extravehicular and intravehicular activity (EVA/IVA) time resource schedule for conducting the missions, and proposed concepts for utilizing remotely operated equipment to perform repetitious or hazardous surface tasks. The operations analysis was performed on a 6 year period of human-tended lunar base operation prior to permanent occupancy. The baseline scenario was derived from a modified version of the civil needs database (CNDB) scenario. This scenario emphasizes achievement of a limited set of science and exploration objectives while emplacing the minimum habitability elements required for a permanent base.

1987-01-01

236

Orbit to surface beamed power for Mars bases expansion  

NASA Technical Reports Server (NTRS)

A scenario is presented wherein the interplanetary supply vehicles for the expansion of the Mars bases are nuclear powered and electrically propelled. For the initial buildup phase supply vehicles need not return to earth but could be utilized as a one-way transport to a Mars synchronous orbit. Upon arriving at Mars, they would land their cargos with one-way descent vehicles. Base personnel would arrive at Mars in separate, faster vehicles. Once the vehicles are in Mars synchronous orbits, the nuclear power system would no longer be needed for propulsion and could be used as an orbital power station beaming its megawatts of power to locations on the surface of the planet. Placing a number of such power systems at strategically located synchronous orbit positions would permit coverage of the major portion of the Martian surface.

Cull, Ronald; Faymon, Karl A.

1989-01-01

237

Whispering gallery mode and surface plasmon resonance based refractometric sensors  

NASA Astrophysics Data System (ADS)

We present four refractometric sensing platforms based on whispering gallery mode (WGM) modulated fluorescence spectra from active microsphere or capillary microresonators and scattered surface plasmon (SP) spectra from rough thin metal coatings and metal nanoparticles in waveguide and fibre dip configurations, respectively. Redshifts of the detected spectra upon increasing sample refractive index are demonstrated for each platform; label-free bio-sensing is also demonstrated.

Rowland, Kristopher J.; François, Alexandre; Sciacca, Beniamino; Monro, Tanya M.

2013-10-01

238

Surface plasmon-based nanopatterning assisted by gold nanospheres  

Microsoft Academic Search

A pulsed laser is used to produce surface plasmon excitation in a monolayer of gold (Au) spheres to nanopattern a silicon substrate. An electrodynamic model accompanies the experimental data, based on the numerical solution to the complete Maxwell’s equations including near- and far-field effects and reflection from the substrate. The Drude-employing finite-difference time-domain method describes the deformation and enhancement of

Alex Heltzel; Senthil Theppakuttai; S C Chen; John R Howell

2008-01-01

239

Surface plasmon-based nanopatterning assisted by gold nanospheres  

Microsoft Academic Search

A pulsed laser is used to produce surface plasmon excitation in a monolayer of gold (Au) spheres to nanopattern a silicon substrate. An electrodynamic model accompanies the experimental data, based on the numerical solution to the complete Maxwell's equations including near- and far-field effects and reflection from the substrate. The Drude-employing finite-difference time-domain method describes the deformation and enhancement of

Alex Heltzel; Senthil Theppakuttai; S. C. Chen; John R. Howell

2008-01-01

240

Microprocessor-based simulator of surface ECG signals  

NASA Astrophysics Data System (ADS)

In this work, a simulator of surface electrocardiogram recorded signals (ECG) is presented. The device, based on a microcontroller and commanded by a personal computer, produces an analog signal resembling actual ECGs, not only in time course and voltage levels, but also in source impedance. The simulator is a useful tool for electrocardiograph calibration and monitoring, to incorporate as well in educational tasks and in clinical environments for early detection of faulty behaviour.

Martínez, A. E.; Rossi, E.; Siri, L. Nicola

2007-11-01

241

Novel Love mode surface acoustic wave based immunosensors  

Microsoft Academic Search

Abstract Love mode,surface acoustic wave (SAW) immunosensors,were developed. The Love mode,guiding layers in these sensors are ZnO and SiO2 thin films. It is shown,that mass sensitivity of the devices with ZnO layer are larger than that of with SiO2 guiding layers. A system comprising dual delay line, based on ZnO\\/908 rotated ST-cut quartz crystal devices, was set up for conducting

Kourosh Kalantar-zadeh; Wojtek Wlodarski; Yuen Y. Chen; Benjamin N. Fry; Kosmas Galatsis

242

Fabry-Pérot-based surface plasmon resonance sensors.  

PubMed

A new sensing approach based on the use of an optical Fabry-Pérot (FP) cavity in conjunction with surface plasmon resonance (SPR) is proposed and theoretically investigated. The impact of the SPR on the intensity and phase response of the proposed sensor structure is evaluated using a modified FP model that takes into account the SPR effect. Compared to the conventional optical-phase-detection-based Kretschmann configuration, the proposed sensing approach requires only the measurement of the output power spectrum over a narrow wavelength span of several nanometers to evaluate the phase responses of the sensor, making it more attractive for practical high-sensitivity sensing applications. PMID:23164845

Xiao, Feng; Li, Guangyuan; Alameh, Kamal; Xu, Anshi

2012-11-15

243

Surfaced-based investigations plan, Volume 4: Yucca Mountain Project  

SciTech Connect

This document represents a detailed summary of design plans for surface-based investigations to be conducted for site characterization of the Yucca Mountain site. These plans are current as of December 1988. The description of surface-based site characterization activities contained in this document is intended to give all interested parties an understanding of the current plans for site characterization of Yucca Mountain. The maps presented in Volume 4 are products of the Geographic Information System (GIS) being used by the Yucca Mountain Project. The ARC/INFO GIS software, developed by Environmental Systems Research Institute, was used to digitize and process these SBIP maps. The maps were prepared using existing US Geological Survey (USGS) maps as a planimetric base. Roads and other surface features were interpreted from a variety of sources and entered into the GIS. Sources include the USGS maps, 1976 USGS orthophotoquads and aerial photography, 1986 and 1987 aerial photography, surveyed coordinates of field sites, and a combination of various maps, figures, descriptions and approximate coordinates of proposed locations for future activities.

NONE

1988-12-01

244

An algorithm for restoring the wafer surface based on B-spline surface reconstruction  

NASA Astrophysics Data System (ADS)

Project lithography has experienced the development of contact, stepper, and step and scan lithography machine. Currently lithography machine has entered the age of twinscan lithography machine. The twinscan lithography machine took advantages of high efficiency and good compatibility, but the focal depth of twinscan lithography machine was only in the nanometer range. In order to guarantee the quality of the exposure, the twinscan lithography machine put forward high request for detecting the map of the wafer surface. Usually, the uniform sampling method and the whole map rebuilding method were used to detect the map of the silicon wafer surface, which is a main cause for the data redundancy. On the other hand, the map reconstructed by this means was not smooth which caused the motor of lithography machine can't response. To avoid these disadvantages, an algorithm for restoring the wafer surface based on B-spline surface reconstruction is proposed in this paper. This method is able to satisfy requirements for the local adaptive refinement, which effectively avoid data redundancy. This method is robust, which means the effect of solving nonlinear problems and inhibiting fuzzy noise is remarkable. The surface reconstructed by this new method is very smooth, which is more suitable for the movement of the motor in lithography machine.

Wang, Nan; Jiang, Wei; Yan, Wei; Hu, Song

2013-08-01

245

On a generalization of the Dirac bracket in the De Donder-Weyl Hamiltonian formalism  

Microsoft Academic Search

The elements of the contrained dynamics algorithm in the De Donder-Weyl (DW) Hamiltonian theory for degenerate Lagrangian theories are discussed. A generalization of the Dirac bracket to the DW Hamiltonian theory with second class constraints (defined in the text) is presented.

I. Kanatchikov

2008-01-01

246

Bracket Brook Micro-Hydroelectric Project. Progress Reports and Final Technical Report.  

National Technical Information Service (NTIS)

Construction of the Bracket Brook micro-hydroelectric system is described, along with preliminary operation. The operating head is 105 ft, or 240 ft of head. It supplies 21,600 kWh of electricity per year. Design insights are given. (ERA citation 11:01290...

1982-01-01

247

Rasetti-Regge Dirac bracket formulation of Lagrangian fluid dynamics of vortex filaments  

Microsoft Academic Search

We review the Rasetti-Regge Dirac bracket (RRDB) for determining the constrained Hamiltonian dynamics of vortex filaments moving with an incompressible potential flow of superfluid helium-II in the Lagrangian fluid picture. We compare the equations for Lagrangian vortex filaments with their corresponding Eulerian vorticity dynamics in the examples of the Euler fluid, superfluid vortices, the local induction approximation (LIA), the Rosenhead

Darryl D. Holm

2003-01-01

248

Effect of Lactic Acid Etching on Bonding Effectiveness of Orthodontic Bracket after Water Storage  

PubMed Central

Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C) 30%, and (D) 50%; group E, 37% phosphoric acid (control). Metal brackets were bonded using a Transbond XT. Bonding effectiveness was assessed by shear bond strength after 24 hours and 6 months of water storage at 37°C. The data were analyzed with 2-way analysis of variance and Tukey's Honestly Significant Difference (HSD) test (? = .001). Results. Lactic acid concentration and water storage resulted in significant differences for brackets bond strength (P < .001). 20% lactic acid had significantly higher mean bond strength values (SD) for all conditions: 24 hours [12.2 (.7) MPa] and 6 months [10.1 (.6) MPa] of water storage. 37% phosphoric acid had intermediate bond strength values for all conditions: 24 hours [8.2 (.6) MPa] and 6 months [6.2 (.6) MPa] of water storage. Also, there were differences in bond strength between storage time, with a reduction in values from 24 hours and 6 months for all experimental groups (P < .001). Conclusion. Lactic acid could be used in place of phosphoric acid as an enamel etchant for bonding of orthodontic brackets.

Alsulaimani, Fahad F.

2014-01-01

249

Comparison of shear bond strength of orthodontic brackets bonded with halogen and plasma arc light curing  

PubMed Central

Background: Reduced time and appropriate bond strength of brackets is one of the most important aspects of orthodontic treatments. Prolonged halogen light curing for bonding of brackets is undesirable, so the purpose of this study was to compare the shear bond strength of brackets bonded with halogen light and plasma arc system. Materials and Mehods: This was an experimental in vitro study. A total of 60 intact premolar teeth were collected and divided into four groups. Stainless steel orthodontic brackets were bonded to them. In groups 1 and 2, curing was done using halogen light given for 20 seconds from two and four angles. In groups 3 and 4, curing was carried out using the plasma arc system for 6 seconds from two and four angles. The shear bond strength was recorded by Instron. The statistics of ANOVA, Tukey's test, and T-test were used in data analysis. Results: There was a statistically significant difference in shear bond strength among the four groups (P = 0.043) and between group 1 with group 2 (P = 0.035). Yet, there was no statistically significant difference between brackets bonded with plasma arc and those bonded with halogen light or between the two groups of plasma arc. Conclusion: Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles.

Toodehzaeim, Mohammad Hossein; Kazemi, Alireza Danesh; Aghili, Hossein Agha; Barzegar, Kazem; Fallahtafti, Taranom

2012-01-01

250

Frictional behavior of stainless steel bracket-wire combinations subjected to small oscillating displacements.  

PubMed

In orthodontic treatment, sliding is frequently used to cause tooth movement. Inherent to this technique is the generation of a counteracting frictional force. In this pilot study, a fretting test consisting of reciprocating tangential displacements was used to investigate test parameters influencing frictional forces during sliding processes. Tests were run at a normal load of 2 N and a frequency of 1 Hz for tangential displacement strokes of 200 microm. Stainless steel orthodontic wires with cross-sections of .017 x .025 in (W17) and .018 x .025 in (W18), and brackets with slot sizes of .018 in (B18) and .022 in (B22) were used. A specific centered positioning method was developed to achieve a parallel alignment of the wire and the bracket slot. The experimental results indicated the significant role of the centered positioning method on the friction value. Implementation of the centered positioning method resulted in a friction force ranging from 0.89 N to 0.97 N at a 200 microm displacement amplitude and 1 Hz frequency, corresponding to a coefficient of friction ranging from 0.45 to 0.49 for the B18-W17 and the B22-W17 bracket-wire combinations, respectively. When the centered positioning method was not used, significantly higher values for the coefficient of friction were found for both bracket-wire combinations. The slot-filling, bracket-wire combinations (B18-W18 and B22-W22) resulted in an increased coefficient of friction and therefore are not recommended as sliding systems. PMID:11606961

Willems, G; Clocheret, K; Celis, J P; Verbeke, G; Chatzicharalampous, E; Carels, C

2001-10-01

251

Intra-patient colon surface registration based on tæniæ coli  

NASA Astrophysics Data System (ADS)

CT colonography, a prevalent tool to diagnose colon cancer in its early stages, is often limited by bad distention, or retained fluids, which will cause segments of the colon to be impossible to process by CAD tools. By scanning patients in both prone and supine positions, collapsed segments and retained fluids will not be in the same place in both images, increasing the length of the colon that can be processed correctly. In order to fully use these two scans, they must be registered, so that a lesion identified on one of them can be mapped to the other, thus increasing sensitivity and specificity of CAD tools. The surface of the colon is however large (more than half a million vertices on our images), and has no canonical shape, which makes atlases and other widely used registration algorithms non optimal. We present in this paper a fast method to register the colon surface between prone and supine scans using landmarks present on the colon, the teniae coli. Our method is composed of three steps. First, we register the body, based on manually placed landmarks. Then we register the three tæniæ coli, and, from this registration, we compute a deformation field for each vertex of the colon surface. We tested our method on 5 cases, by measuring the RMS error after body registration, quantifying the intrisic movement of the colon, and after colon surface registration. The RMS error was reduced from 1.8 cm to 0.49 cm, a reduction of 71%.

Lamy, Julien; Summers, Ronald M.

2007-03-01

252

GPGPU-based surface inspection from structured white light  

NASA Astrophysics Data System (ADS)

Automatic surface inspection has been used in the industry to reliably detect all kinds of surface defects and to measure the overall quality of a produced piece. Structured light systems (SLS) are based on the reconstruction of the 3D information of a selected area by projecting several phase-shifted sinusoidal patterns onto a surface. Due to the high speed of production lines, surface inspection systems require extremely fast imaging methods and lots of computational power. The cost of such systems can easily become considerable. The use of standard PCs and Graphics Processing Units (GPUs) for data processing tasks facilitates the construction of cost-effective systems. We present a parallel implementation of the required algorithms written in C with CUDA extensions. In our contribution, we describe the challenges of the design on a GPU, compared with a traditional CPU implementation. We provide a qualitative evaluation of the results and a comparison of the algorithm speed performance on several platforms. The system is able to compute two megapixels height maps with 100 micrometers spatial resolution in less than 200ms on a mid-budget laptop. Our GPU implementation runs about ten times faster than our previous C code implementation.

Bordallo López, Miguel; Niemelä, Karri; Silvén, Olli

2012-02-01

253

Vitrified collagen-based conjunctival equivalent for ocular surface reconstruction.  

PubMed

The main functions of the conjunctiva, an essential part of the ocular surface, are to maintain the equilibrium of the tear film and to protect the eye. Upon injuries, the prerequisite to successful ocular surface repair is conjunctival reconstruction. Tissue engineering techniques, including transplantation of autografts, amniotic membranes and numerous synthetic/natural materials, have been developed. However, none of these strategies is completely satisfactory due to lack of goblet cell repopulation, poor mechanical properties or non-standardized preparation procedure. Here, we cultured conjunctival epithelial cells on vitrified collagen membranes and developed a tissue equivalent for repairing damaged conjunctiva. Optimized vitrified collagen has superior mechanical and optical properties to previous biomaterials for ocular surface application, and its unique fibrillar structure significantly benefited conjunctival epithelial cell growth and the phenotypic development in vitro. In a rabbit model, vitrified collagen greatly promoted conjunctival regeneration with rapid re-epithelization, sufficient repopulation of goblet cells and minimized fibrosis and wound contracture, proved by gene expression analyses and histological staining. In conclusion, we have demonstrated the potential suitability of utilizing vitrified collagen-based tissue equivalent in ocular surface reconstruction. PMID:24933512

Zhou, Huifang; Lu, Qiaozhi; Guo, Qiongyu; Chae, Jemin; Fan, Xianqun; Elisseeff, Jennifer H; Grant, Michael P

2014-08-01

254

Graphene-based high-performance surface plasmon resonance biosensors  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) biosensors have become a central tool for the study of biomolecular interactions, chemical detection, and immunoassays in various fields. SPR biosensors offer unparalleled advantages such as label-free and real-time analysis with very high sensitivity. To further push the limits of SPR capabilities, novel SPR structures and approaches are being actively investigated. Here we experimentally demonstrate a graphene-based SPR biosensor. By incorporating a graphene layer to the conventional gold thin film SPR structure, its biosensing sensitivity is significantly increased. This is shown in a typical affinity biosensing experiment to measure the real-time binding kinetics of biotin-streptavidin. In addition to higher sensitivity, we also obtain a much higher signal-to-noise ratio without the slightest modification of the usual measurement setup. This implies that a considerably lower limit of detection can be made possible with the novel structure. Moreover, our graphene-based SPR biosensors do not require sophisticated surface functionalization schemes as in conventional SPR in order to function. Previous reports have also suggested that graphene might effectively prevent non-specific binding of biomolecules on the sensor surface. With relatively simple fabrication methods and large scalability, these combined distinctive advantages can enable future generation of high-performance SPR biosensors.

Wijaya, E.; Maalouli, N.; Boukherroub, R.; Szunerits, S.; Vilcot, J.-P.

2012-05-01

255

Erosion In Surface-based Modeling Using Tank Experiment Data  

NASA Astrophysics Data System (ADS)

The purpose of reservoir characterization is to reproduce the complex heterogeneity of permeability. In the case of deepwater lobate reservoirs, the interbed, subseismic scale shale layers are impermeable and greatly laterally continuous, which determines that the shale layer coverage is one of the most important model parameters to the reservoir permeability and should be modeled explicitly. One challenge of modeling erosion in deepwater environment is the extremely limited data. In the early appraisal stage of a deepwater reservoir, only a handful of wells and low resolution seismic data are obtained, which impede further understanding of the complex stratigraphy and structures. The contribution of this work is the use of tank experiment as a new data source for reservoir modeling. The advantage of tank experiment over a 2D outcrop is that the deposition-erosion processes are recorded in real time for their whole period, so geometry of deposited sediment bodies and erosion caused by them can be inferred. Data recorded from a delta basin experiment, in the form of intermediate elevations and correlated overhead photos, are used in this work. The elevation changes in response to ongoing deposition-erosion processes, implying thickness of deposition and depth of erosion; the overhead photos provide information of channel-lobe horizontal boundaries. In this work, we developed a workflow of using information in tank experiment data to build reservoir models. First of all, deposition and erosion geometries are extracted and visualized from changes of intermediate elevations. Because the tank experiment is not designed to simulate any real scale environment, we characterized the uncertainty of deposition and erosion gemetries, and the uncertainty of relationship between deposition-erosion geometries by distributions of several specifically chosen dimensionless ratios. In the second step, the distributions are used as input parameters to a technique known as surface-based modeling. In surface-based modeling, channel-lobe bodies, whose dimensionless ratios are drawn from input distributions, are generated sequentially. Each body is placed in a topography surface using depositional rules, and the stacked channel-lobe sequence forms a 3D reservoir model. We have demonstrated the simulation procedure of a surface-based model and comparison of simulation and tank experiment data reveals that surface-based model can reproduce the input distributions from tank experiment data and provide realistic stratigraphy of a lobate reservoir.

Xu, S.; Mukerji, T.; Caers, J.

2012-12-01

256

Subpixel measurement of image features based on paraboloid surface fit  

SciTech Connect

A digital image processing inspection system is under development at Oak Ridge National Laboratory that will locate image features on printed material and measure distances between them to accuracies of 0.001 in. An algorithm has been developed for this system that can locate unique image features to subpixel accuracies. It is based on a least-squares fit of a paraboloid function to the surface generated by correlating a reference image feature against a test image search area. normalizing the correlation surface makes the algorithm robust in the presence of illumination variations and local flaws. Subpixel accuracies better than 1/16 of a pixel have been achieved using a variety of different reference image features. 5 refs., 6 figs.

Gleason, S.S.; Hunt, M.A.; Jatko, W.B.

1990-01-01

257

Tapered optical fiber sensor based on localized surface plasmon resonance.  

PubMed

A tapered fiber localized surface plasmon resonance (LSPR) sensor is demonstrated for refractive index sensing and label-free biochemical detection. The sensing strategy relies on the interrogation of the transmission intensity change due to the evanescent field absorption of immobilized gold nanoparticles on the tapered fiber surface. The refractive index resolution based on the interrogation of transmission intensity change is calculated to be 3.2×10?? RIU. The feasibility of DNP-functionalized tapered fiber LSPR sensor in monitoring anti-DNP antibody with different concentrations spiked in buffer is examined. Results suggest that the compact sensor can perform qualitative and quantitative biochemical detection in real-time and thus has potential to be used in biomolecular sensing applications. PMID:23037288

Lin, Hsing-Ying; Huang, Chen-Han; Cheng, Gia-Ling; Chen, Nan-Kuang; Chui, Hsiang-Chen

2012-09-10

258

Static-dynamic friction transition of FRP esthetic orthodontic wires on various brackets by suspension-type friction test.  

PubMed

A new testing apparatus for the measurement of frictional properties was designed and the frictional coefficients were obtained and compared with each other in various combinations of brackets and orthodontic wires, including esthetic fiber-reinforced plastic (FRP) wire that was especially designed and manufactured. Three kinds of wires (stainless steel, nickel-titanium, and FRP) and four brackets (single-crystal alumina, polycrystalline alumina, polycarbonate, and stainless steel) were used. The testing was done under dry and wet conditions. The friction testing equipment was designed to attach the bracket to a C-shaped bar suspended with a variable mass, and sliding along a fixed wire. The transition between static and dynamic friction was measured as a breakaway force, with the use of a universal test machine. In addition to material properties, this testing fixture eliminates geometrical factors, such as the rotational moment at the edge of the bracket slot, deflection of the orthodontic wire, and tension of the ligature wire. Nearly ideal frictional properties between materials are obtained. The frictional properties of FRP wire were similar to those of metal wires on all brackets, except the polycrystalline alumina bracket. The frictional coefficient between the polycrystalline ceramic bracket and FRP wire was larger than that of other combinations. There was little difference in frictional coefficients between dry and wet conditions. PMID:14598404

Suwa, N; Watari, F; Yamagata, S; Iida, J; Kobayashi, M

2003-11-15

259

Applying tensor-based morphometry to parametric surfaces can improve MRI-based disease diagnosis.  

PubMed

Many methods have been proposed for computer-assisted diagnostic classification. Full tensor information and machine learning with 3D maps derived from brain images may help detect subtle differences or classify subjects into different groups. Here we develop a new approach to apply tensor-based morphometry to parametric surface models for diagnostic classification. We use this approach to identify cortical surface features for use in diagnostic classifiers. First, with holomorphic 1-forms, we compute an efficient and accurate conformal mapping from a multiply connected mesh to the so-called slit domain. Next, the surface parameterization approach provides a natural way to register anatomical surfaces across subjects using a constrained harmonic map. To analyze anatomical differences, we then analyze the full Riemannian surface metric tensors, which retain multivariate information on local surface geometry. As the number of voxels in a 3D image is large, sparse learning is a promising method to select a subset of imaging features and to improve classification accuracy. Focusing on vertices with greatest effect sizes, we train a diagnostic classifier using the surface features selected by an L1-norm based sparse learning method. Stability selection is applied to validate the selected feature sets. We tested the algorithm on MRI-derived cortical surfaces from 42 subjects with genetically confirmed Williams syndrome and 40 age-matched controls, multivariate statistics on the local tensors gave greater effect sizes for detecting group differences relative to other TBM-based statistics including analysis of the Jacobian determinant and the largest eigenvalue of the surface metric. Our method also gave reasonable classification results relative to the Jacobian determinant, the pair of eigenvalues of the Jacobian matrix and volume features. This analysis pipeline may boost the power of morphometry studies, and may assist with image-based classification. PMID:23435208

Wang, Yalin; Yuan, Lei; Shi, Jie; Greve, Alexander; Ye, Jieping; Toga, Arthur W; Reiss, Allan L; Thompson, Paul M

2013-07-01

260

APPLYING TENSOR-BASED MORPHOMETRY TO PARAMETRIC SURFACES CAN IMPROVE MRI-BASED DISEASE DIAGNOSIS  

PubMed Central

Many methods have been proposed for computer-assisted diagnostic classification. Full tensor information and machine learning with 3D maps derived from brain images may help detect subtle differences or classify subjects into different groups. Here we develop a new approach to apply tensor-based morphometry to parametric surface models for diagnostic classification. We use this approach to identify cortical surface features for use in diagnostic classifiers. First, with holomorphic 1-forms, we compute an efficient and accurate conformal mapping from a multiply connected mesh to the so-called slit domain. Next, the surface parameterization approach provides a natural way to register anatomical surfaces across subjects using a constrained harmonic map. To analyze anatomical differences, we then analyze the full Riemannian surface metric tensors, which retain multivariate information on local surface geometry. As the number of voxels in a 3D image is large, sparse learning is a promising method to select a subset of imaging features and to improve classification accuracy. Focusing on vertices with greatest effect sizes, we train a diagnostic classifier using the surface features selected by an ?1-norm based sparse learning method. Stability selection is applied to validate the selected feature sets. We tested the algorithm on MRI-derived cortical surfaces from 42 subjects with genetically confirmed Williams syndrome and 40 age-matched controls, multivariate statistics on the local tensors gave greater effect sizes for detecting group differences relative to other TBM-based statistics including analysis of the Jacobian determinant and the largest eigenvalue of the surface metric. Our method also gave reasonable classification results relative to the Jacobian determinant, the pair of eigenvalues of the Jacobian matrix and volume features. This analysis pipeline may boost the power of morphometry studies, and may assist with image-based classification.

Wang, Yalin; Yuan, Lei; Shi, Jie; Greve, Alexander; Ye, Jieping; Toga, Arthur W.; Reiss, Allan L.; Thompson, Paul M.

2013-01-01

261

Wide steering angle microscanner based on curved surface  

NASA Astrophysics Data System (ADS)

Intensive industrial and academic research is oriented towards the design and fabrication of optical beam steering systems based on MEMS technology. In most of these systems, the scanning is achieved by rotating a flat micromirror around a central axis in which the main challenge is achieving a wide mirror rotation angle. In this work, a novel method of optical beam scanning based on reflection from a curved surface is presented. The scanning occurs when the optical axis of the curved surface is displaced with respect to the optical axis of the incident beam. To overcome the possible deformation of the spot with the scanning angle, the curved surface is designed with a specific aspherical profile. Moreover, the scanning exhibits a more linearized scanning angle-displacement relation than the conventional spherical profile. The presented scanner is fabricated using DRIE technology on an SOI wafer. The curved surface (reflector) is metalized and attached to a comb-drive actuator fabricated in the same lithography step. A single-mode fiber, behaving as a Gaussian beam source, is positioned on the substrate facing the mirror. The reflected optical beam angle and spotsize in the far field is recorded versus the relative shift between the fiber and the curved mirror. The spot size is plotted versus the scanning angle and a scanning spot size uniformity of about +/-10% is obtained for optical deflection angles up to 100 degrees. As the optical beam is propagating parallel to the wafer substrate, a completely integrated laser scanner can be achieved with filters and actuators self-aligned on the same chip that allows low cost and mass production of this important product.

Sabry, Yasser; Khalil, Diaa; Saadany, Bassam; Bourouina, Tarik

2013-03-01

262

Localized surface plasmon resonance based fiber optic sensor with nanoparticles  

NASA Astrophysics Data System (ADS)

A localized surface plasmon resonance (LSPR) based fiber optic sensor with a nanoparticle layer coated on the core of the optical fiber has been presented and theoretically analyzed. Nanoparticles of four materials: ITO, Au, Ag and Cu have been considered for the study. The complete analysis of sensitivity of the LSPR based fiber optic sensor with each nanoparticle layer individually for various values of thickness and particle size has been done numerically in order to use these four materials in plasmonic sensing applications. The sensitivity of LSPR based fiber optic sensor increases with the increase in the thickness of nanoparticles layer for all four materials. Also, for a fixed value of thickness of nanoparticles layer, the sensitivity of LSPR based fiber optic sensor further increases as the particle size of nanoparticles increases (up to 20 nm). The optimized values of thickness and particle size of nanoparticles layers for all four materials individually are revealed to be 60 nm and 20 nm respectively. With sensitivity of 6240 nm/RIU, the 60 nm thick ITO nanoparticles layer (with 20 nm particle size) based LSPR sensor has been shown to have better performance than other three material's naoparticles based LSPR sensors.

Rani, Mahima; Sharma, Navneet K.; Sajal, Vivek

2013-04-01

263

An Ab Initio Based Potential Energy Surface for Water  

NASA Technical Reports Server (NTRS)

We report a new determination of the water potential energy surface. A high quality ab initio potential energy surface (PES) and dipole moment function of water have been computed. This PES is empirically adjusted to improve the agreement between the computed line positions and those from the HITRAN 92 data base. The adjustment is small, nonetheless including an estimate of core (oxygen 1s) electron correlation greatly improves the agreement with experiment. Of the 27,245 assigned transitions in the HITRAN 92 data base for H2(O-16), the overall root mean square (rms) deviation between the computed and observed line positions is 0.125/cm. However the deviations do not correspond to a normal distribution: 69% of the lines have errors less than 0.05/cm. Overall, the agreement between the line intensities computed in the present work and those contained in the data base is quite good, however there are a significant number of line strengths which differ greatly.

Partridge, Harry; Schwenke, David W.; Langhoff, Stephen R. (Technical Monitor)

1996-01-01

264

Localized surface plasmon resonance of silver nanoisland based glucose sensor  

NASA Astrophysics Data System (ADS)

Study of optical properties of glucose is an attractive research topic for years. One of the goals is to develop a portable device for simple, reliable, cost effective and non-invasive monitoring of glucose in blood for diabetics. In this work, we study localized surface plasmon resonance (LSPR) of Ag nanoisland based glucose sensor. The progressive shift in LSPR caused by the various concentration of glucose from 2M to 10M has been investigated to monitor the sensing property. We correlate the redshift of LSPR is due to the change in refractive index of surrounding glucose medium. Preliminary results show that this may possibly reveal a new pathway for sensing glucose.

Venugopal, N.; Mitra, Anirban

2013-06-01

265

Progress report on microstructured surfaces based on chemical vapor deposition.  

PubMed

This book chapter discusses recent advances in the fabrication of microscale surface patterns using chemical vapor deposition polymerization. Reactive poly(p-xylylene) (PPX) coatings are useful for their ability to immobilize specific biomolecules, as determined by the PPX functional group. PPXs can either be modified postdeposition, or they can be patterned onto a substrate in situ. Specific methods discussed in this progress report include microcontact printing, vapor-assisted micropatterning in replica structures, projection lithography-based patterning, and selective polymer deposition. PMID:20967636

Elkasabi, Yaseen; Lahann, Joerg

2011-01-01

266

Three-dimensional surface reconstruction based on laser triangulation  

NASA Astrophysics Data System (ADS)

At the present time, a great number of applications exist that need the reconstruction of three-dimensional surfaces, such as: medicine, reverse engineer, industrial tasks and virtual world recreation. A system of reconstruction of surfaces was made up of three parts: capture of image, calibration of the camera and generation of a mesh from the cloud of three-dimensional points (3D). The data 3D is captured using the principle of triangulation between a camera or receiver, a generator of structured light (emitting laser) and the object. The capture of the image is made through a digital camera, having used a set of algorithms developed in Borland C++ Builder5. For the camera's calibration the method of flexible calibration was implemented (Zhang, 2002), which consists of a solution of closed form, followed by a nonlinear refinement based on the criterion of maximal probability. In order to generate the three-dimensional surface a rectangular mesh was create using a set of B-spline curves.

Lizcano, C.; Marquez, M.

2004-10-01

267

Osteoconductive Protamine-based Polyelectrolyte Multilayer Functionalized Surfaces  

PubMed Central

The integration of orthopedic implants with host bone presents a major challenge in joint arthroplasty, spinal fusion and tumor reconstruction. The cellular microenvironment can be programmed via implant surface functionalization allowing direct modulation of osteoblast adhesion, proliferation, and differentiation at the implant-bone interface. The development of layer-by-layer assembled polyelectrolyte multilayer (PEM) architectures has greatly expanded our ability to fabricate intricate nanometer to micron scale thin film coatings that conform to complex implant geometries. The in vivo therapeutic efficacy of thin PEM implant coatings for numerous biomedical applications has previously been reported. We have fabricated protamine-based PEM thin films that support the long-term proliferation and differentiation of pre-osteoblast cells on non-cross-linked film coated surfaces. These hydrophilic PEM functionalized surfaces with nanometer-scale roughness facilitated increased deposition of calcified matrix by osteoblasts in vitro, and thus offer the potential to enhance implant integration with host bone. The coatings can make an immediate impact in the osteogenic culture of stem cells and assessment of the osteogenic potential of new therapeutic factors.

Samuel, Raymond E.; Shukla, Anita; Paik, Daniel H.; Wang, Mary X.; Fang, Jean C.; Schmidt, Daniel J.

2011-01-01

268

Small reactor power systems for manned planetary surface bases  

NASA Astrophysics Data System (ADS)

A preliminary feasibility study of the potential application of small nuclear reactor space power systems to manned planetary surface base missions was conducted. The purpose of the study was to identify and assess the technology, performance, and safety issues associated with integration of reactor power systems with an evolutionary manned planetary surface exploration scenario. The requirements and characteristics of a variety of human-rated modular reactor power system configurations selected for a range of power levels from 25 kWe to hundreds of kilowatts is described. Trade-off analyses for reactor power systems utilizing both man-made and indigenous shielding materials are provided to examine performance, installation and operational safety feasibility issues. The results of this study have confirmed the preliminary feasibility of a wide variety of small reactor power plant configurations for growth oriented manned planetary surface exploration missions. The capability for power level growth with increasing manned presence, while maintaining safe radiation levels, was favorably assessed for nominal 25 to 100 kWe modular configurations. No feasibility limitations or technical barriers were identified and the use of both distance and indigenous planetary soil material for human rated radiation shielding were shown to be viable and attractive options.

Bloomfield, Harvey S.

1987-12-01

269

Small reactor power systems for manned planetary surface bases  

NASA Technical Reports Server (NTRS)

A preliminary feasibility study of the potential application of small nuclear reactor space power systems to manned planetary surface base missions was conducted. The purpose of the study was to identify and assess the technology, performance, and safety issues associated with integration of reactor power systems with an evolutionary manned planetary surface exploration scenario. The requirements and characteristics of a variety of human-rated modular reactor power system configurations selected for a range of power levels from 25 kWe to hundreds of kilowatts is described. Trade-off analyses for reactor power systems utilizing both man-made and indigenous shielding materials are provided to examine performance, installation and operational safety feasibility issues. The results of this study have confirmed the preliminary feasibility of a wide variety of small reactor power plant configurations for growth oriented manned planetary surface exploration missions. The capability for power level growth with increasing manned presence, while maintaining safe radiation levels, was favorably assessed for nominal 25 to 100 kWe modular configurations. No feasibility limitations or technical barriers were identified and the use of both distance and indigenous planetary soil material for human rated radiation shielding were shown to be viable and attractive options.

Bloomfield, Harvey S.

1987-01-01

270

Subwavelength surface plasmons based on novel structures and metamaterials  

NASA Astrophysics Data System (ADS)

With the rapid development of nanofabrication technology and powerful computational tools over the last decade, nanophotonics has enjoyed tremendous innovation and found wide applications in ultrahigh-speed data transmission, sensitive optical detection, manipulation of ultra-small objects, and visualization of nanoscale patterns. Surface plasmon-based photonics (or plasmonics) merges electronics and photonics at the nanoscale, creating the ability to combine the superior technical advantages of photonics and electronics on the same chip. Plasmonics focuses on the innovation of photonic devices by exploiting the optical property of metals. In particular, the oscillation of free electrons, when properly driven by electromagnetic waves, would form plasmon-polaritons in the vicinity of a metal surface and potentially result in extreme light confinement, which may beat the diffraction limit faced by conventional photonic devices and enable greatly enhanced light-matter interactions at the deep subwavelength scale. The objective of this dissertation is to develop subwavelength or deep subwavelength plasmonic waveguides and explore their integration on conventional dielectric platforms for multiple applications. Three novel structures (or mechanisms) are employed to develop and integrate nanoplasmonic waveguides; each consists of one part of the dissertation. The first part of this dissertation covers the design, fabrication, and demonstration of two-dimensional and three-dimensional metal-insulator-metal plasmonic couplers for mode transformation between photonic and nanoplasmonic domains on the silicon-on-insulator platform. In particular, deep subwavelength plasmonic modes under 100-nm are achieved via end-fire coupling and adiabatic mode transformation at telecom wavelengths. The second part studies metallic gratings as spoof plasmonic waveguides hosting deep subwavelength surface propagation modes. Metallic gratings under different dielectric coatings are numerically investigated for terahertz and gigahertz regions. The third part proposes, explores, and experimentally demonstrates the "metametal" for super surface wave excitation based on multilayered metal-insulator stacks, where the dispersion of the supported surface modes can be engineered by insulator dopant films in a given metal. The final part discusses the potential applications of active plasmonics for optical sensing, modulation and photovoltaics.

Yang, Ruoxi

271

Cell Kinase Activity Assay Based on Surface Enhanced Raman Spectroscopy  

PubMed Central

Kinases control many important aspects of cell behavior, such as signal transduction, growth/differentiation, and tumorogenesis. Current methods for assessing kinase activity often require specific antibodies, and/or radioactive labeling. Here we demonstrated a novel detection method to assess kinase activity based on surface enhanced Raman spectroscopy (SERS). Raman signal was obtained after amplification by silver nanoparticles. The sensitivity of this method was comparable to fluorescence measurement of peptide concentration. When purified kinase enzyme was used, the detection limit was comparable to conventional radio-labeling method. We further demonstrated the feasibility to measure kinase activity in crude cell lysate. We suggested this SERS-based kinase activity assay could be a new tool for biomedical research and application.

Yue, Zhicao; Zhuang, Fengfeng; Kumar, Rajar; Wong, Ieong; Cronin, Stephen B; Liu, Yi-Hsin

2009-01-01

272

A large surface photomultiplier based on SiPMs  

NASA Astrophysics Data System (ADS)

Light detection through photosensitive devices represents one of the key issues for a large variety of experiments. In the recent years, Silicon PhotoMultipliers (SiPMs) based on limited Geiger-mode avalanche have been extensively studied in view of their future applications. However, their use is strongly limited by their small sensitive surfaces and by the fact that any increment in the surface turns out into an increase of the dark count rate. In the present work we describe the dark count rate reduction obtained by using a FPGA-based logical circuit for fast pre-processing of pulses from a 3×3 matrix of SiPMs. The prototype we developed supports two SiPMs: we show that a rate reduction from 6.6 Mcps (Mega counts per second) down to 0.436 Mcps at the lowest threshold (0.5 photon-equivalent) and from 1.2 kcps down to 0.02 cps for the highest threshold (3.5 photon-equivalent) is obtainable.

Barbarino, Giancarlo; de Asmundis, Riccardo; De Rosa, Gianfranca; Vivolo, Daniele; Mollo, Carlos Maximiliano

2013-10-01

273

Surface modification of nickel based alloys for improved oxidation resistance  

SciTech Connect

The present research is aimed at the evaluation of a surface modification treatment to enhance the high temperature stability of nickel-base superalloys. A low Coefficient Thermal Expansion (CTE ~12.5x10-6/°C) alloy based on the composition (in weight %) of Ni-22Mo-12.5Cr was produced by Vacuum Induction Melting and Vacuum Arc Melting and reduced to sheet by conventional thermal-mechanical processing. A surface treatment was devised to enhance the oxidation resistance of the alloys at high temperature. Oxidation tests (in dry and wet air; treated and untreated) were conducted 800°C to evaluate the oxidation resistance of the alloys. The results were compared to the behavior of Haynes 230 (Ni-22Cr) in the treated and untreated conditions. The treatment was not very effective for Haynes 230, as this alloy had similar oxidation behavior in both the treated and untreated conditions. However, the treatment had a significant effect on the behavior of the low CTE alloy. At 800°C, the untreated Ni-12.5Cr alloy was 5 times less oxidation resistant than Haynes 230. However, in the treated condition, the Ni-12.5Cr alloy had comparable oxidation resistance to the Haynes 230 alloy.

Jablonski, Paul D.; Alman, David E.

2005-02-01

274

Surface relief gratings in azobenzene supramolecular systems based on polyimides  

NASA Astrophysics Data System (ADS)

The paper describes formation of new supramolecular azopolymers based on hydrogen bonds as perspective materials for laser induced surface relief gratings (SRGs) and for polarization gratings. Supramolecular films were built on the basis of hydrogen bonds between the functional groups of polymer and azobenzene derivatives, that is 4-[4-(3-hydroxypropyloxy)phenylazo]-pyridine and 4-[4-(6-hydroxyhexyloxy)phenylazo]pyridine. Polymers with imide rings, i.e., poly(esterimide)s and poly(etherimide)s, with phenolic hydroxyl or carboxylic groups were applied as matrixes for polymer-dye supramolecular systems. They revealed glass transition temperatures (Tg) in the range of 170-260 °C, whereas supramolecular systems exhibited lower Tg (88-187 °C). The polymers were easily soluble in aprotic polar solvents and exhibited remarkable good film forming properties. Moreover, new chromophore 4-[4-(3-hydroxypropyloxy)phenylazo]pyridine was synthesized and characterized. The light induced SRGs formation and simultaneous formation of the polarization gratings were explored in prepared polymer-chromophore assembles films using a holographic grating recording technique. First time to the best of our knowledge SRGs were formed in hydrogen-bonded supramolecular systems based on polyimides. The highest SRG amplitude and thus the highest diffraction efficiency were obtained in poly(esterimide)s with the hydroxyl functional group. Additionally, the thermal stability of the photoinduced surface gratings and polarization gratings were tested revealing in the case of the SRGs partial stability and almost complete erasure of the polarization gratings.

Schab-Balcerzak, Ewa; Sobolewska, Anna; Stumpe, Joachim; Hamryszak, Lukasz; Bujak, Piotr

2012-12-01

275

Comparative performance of AVHRR-based multichannel sea surface temperatures  

NASA Astrophysics Data System (ADS)

A brief outline of the basic concepts of cloud filtering and atmospheric attenuation corrections used in the Multi-channel Sea Surface Temperature (MCSST) method is given. The operational MCSST procedures and products are described in detail. The comparative performance of AVHRR-based MCSST'S is discussed via the use of the results of the JPL Satellite-Derived Sea Surface Temperature workshops. For the four data periods there is surprisingly good correspondence in the sign and location of the major monthly mean SST anomaly features derived from MCSST's and those from a screened set of ship-based SST's. With the partial exception of the one data period severely affected in some areas by volcanic aerosol from El Chichon eruptions, global statistical measures of the MCSST anomalies relative to the the ship data are as follows: biases, 0.3-0.4°C (MCSST lower than ship); standard deviations, 0.5-0.6°C; and cross-correlations, +0.3 to +0.7. A refined technique in use with NOAA 9 data in 1985 has yielded consistent biases and rms differences near -0.1°C and 0.5°C, respectively.

McClain, E. Paul; Pichel, William G.; Walton, Charles C.

1985-11-01

276

Detecting surface deformation by phase stacking based on the PS  

NASA Astrophysics Data System (ADS)

In the surface deformation monitoring, synthetic aperture radar differential interferometry (D-InSAR) has the advantages of all-weather, large-scale and high accuracy, it is hard to form interferogram for limited factors such as spatial decorrelation, temporal decorrelation and atmospheric effect. For the reason, the method of PS-DInSAR was proposed. However, the method needs so many SAR images, more than twenty scenes. Therefore, the method based on the phase stacking of PS for surface deformation monitoring was proposed and verified. The PS-DInSAR model and D-InSAR model are combined and simplified under certain conditions that assume the phase error of atmospheric disturbances are random and equal in an interferogram and the deformation is linear. The optimal master image for interferometric combinations is selected by comprehensive correlation function model. Then the PS points are detected and the Delaunay triangle is established according to the PS. The Minimum Cost Flow is used based on the Delaunay triangle of PS to unwrap the phase. Then the deformation and deformation rate are obtained by the linear analysis for temporal series of interferograms. At last, nine ENVISAT images captured during 2003.6-2006.3 in Tianjin area were processed, and the mean subsidence rate of this area was obtained.

Hao, Ming; Deng, Kazhong; Fan, Hongdong

2011-06-01

277

Lunar surface base propulsion system study, volume 1  

NASA Technical Reports Server (NTRS)

The efficiency, capability, and evolution of a lunar base will be largely dependent on the transportation system that supports it. Beyond Space Station in low Earth orbit (LEO), a Lunar-derived propellant supply could provide the most important resource for the transportation infrastructure. The key to an efficient Lunar base propulsion system is the degree of Lunar self-sufficiency (from Earth supply) and reasonable propulsion system performance. Lunar surface propellant production requirements must be accounted in the measurement of efficiency of the entire space transportation system. Of all chemical propellant/propulsion systems considered, hydrogen/oxygen (H/O) OTVs appear most desirable, while both H/O and aluminum/oxygen propulsion systems may be considered for the lander. Aluminized-hydrogen/oxygen and Silane/oxygen propulsion systems are also promising candidates. Lunar propellant availability and processing techniques, chemical propulsion/vehicle design characteristics, and the associated performance of the total transportation infrastructure are reviewed, conceptual propulsion system designs and vehicle/basing concepts, and technology requirements are assessed in context of a Lunar Base mission scenario.

1987-01-01

278

Engineering aperiodic nanostructured surfaces for scattering-based optical devices  

NASA Astrophysics Data System (ADS)

Novel optical devices such as biosensors, color displays and authentication devices can be obtained from the distinctive light scattering properties of resonant nanoparticles and nanostructured arrays. These arrays can be optimized through the choice of material, particle morphology and array geometry. In this thesis, by engineering the multi-frequency colorimetric responses of deterministic aperiodic nanostructured surfaces (DANS) with various spectral Fourier properties, I designed, fabricated and characterized scattering-based devices for optical biosensing and structural coloration applications. In particular, using analytical and numerical optimization, colorimetric biosensors are designed and fabricated with conventional electron beam lithography, and characterized using dark-field scattering imaging as well as image autocorrelation analysis of scattered intensity in the visible spectral range. These sensors, which consist of aperiodic surfaces ranging from quasi-periodic to pseudo-random structures with flat Fourier spectra, sustain highly complex structural resonances that enable a novel optical sensing approach beyond the traditional Bragg scattering. To this end, I have experimentally demonstrated that DANS with engineered structural colors are capable of detecting nanoscale protein monolayers with significantly enhanced sensitivity over periodic structures. In addition, different aperiodic arrays of gold (Au) nanoparticles are integrated with polydimethylsiloxane (PDMS) microfluidic structures by soft-lithographic micro-imprint techniques. Distinctive scattering spectral shifts and spatial modifications of structural color patterns in response to refractive index variations were simultaneously measured. The successful integration of DANS with microfluidics technology has introduced a novel opto-fluidic sensing platform for label-free and multiplexed lab-on-a-chip applications. Moreover, by studying the isotropic scattering properties of homogenized Pinwheel aperiodic arrays, angle-insensitive (i.e. isotropic) coloration from nanostructured metal surfaces can be designed and optimized without randomization. Pinwheel nanoparticle arrays on a gold thin film were fabricated for the first time and investigated using dark-field scattering and angle-resolved reflectivity measurements. In sharp contrast to the colorimetric responses of periodically nanopatterned surfaces, which strongly depend on the observation angle, spatially uniform and isotropic green coloration of gold films were demonstrated using these engineered metal surfaces. In addition, the intensity of the scattered light is enhanced by plasmonic resonance originated from gold nanoparticles deposited on the gold substrates. The development of the enhanced isotropic scattering devices could advance plasmonic applications to color display, optical tagging and colorimetric sensing technologies.

Lee, Yuk Kwan Sylvanus

279

Evaluation of volume-based and surface-based brain image registration methods  

PubMed Central

Establishing correspondences across brains for the purposes of comparison and group analysis is almost universally done by registering images to one another either directly or via a template. However, there are many registration algorithms to choose from. A recent evaluation of fully automated nonlinear deformation methods applied to brain image registration was restricted to volume-based methods. The present study is the first that directly compares some of the most accurate of these volume registration methods with surface registration methods, as well as the first study to compare registrations of whole-head and brain-only (de-skulled) images. We used permutation tests to compare the overlap or Hausdorff distance performance for more than 16,000 registrations between 80 manually labeled brain images. We compared every combination of volume-based and surface-based labels, registration, and evaluation. Our primary findings are the following: 1. de-skulling aids volume registration methods; 2. custom-made optimal average templates improve registration over direct pairwise registration; and 3. resampling volume labels on surfaces or converting surface labels to volumes introduces distortions that preclude a fair comparison between the highest ranking volume and surface registration methods using present resampling methods. From the results of this study, we recommend constructing a custom template from a limited sample drawn from the same or a similar representative population, using the same algorithm used for registering brains to the template.

Klein, Arno; Ghosh, Satrajit S.; Avants, Brian; Yeo, B.T.T.; Fischl, Bruce; Ardekani, Babak; Gee, James C.; Mann, J.J.; Parsey, Ramin V.

2010-01-01

280

Bracketed Two-Level Grammars - A Decidable and Practical Approach to Language Definitions  

Microsoft Academic Search

Bracketed two-level grammars are not a variation of two-level grammars (van Wijngaarden grammars) but consitute a restriction within the general scheme. The resulting grammars give rise to an effective top-down analysis, where the replacement of metanotions is governed by rules similar to the evaluation dependencies in attribute grammars. Supplemented by the formalized concept of predicates, the class of languages is

Lutz Michael Wegner; Formale Beschreibungsverfahren

1979-01-01

281

Evaluation of acquired acid resistance of enamel surrounding orthodontic brackets irradiated by laser and fluoride application.  

PubMed

Demineralization of enamel around orthodontic brackets is a clinical problem which can lead to some esthetic concerns like white spot lesions. The aim of this in vitro study was to evaluate the effect of the Er, Cr:YSGG laser and fluoride application on the acid resistance of enamel adjacent to orthodontic brackets. A total of 60 healthy, permanent, human premolars were selected and bonded with brackets, then they were randomly assigned to four groups (n?=?15): topical APF gel (1.23 % F, pH 3.5, for 4 min); Er,Cr:YSGG laser (P:0.25 W, E:12.5 mJ, RR:20 Hz, PD:140 ?s, 11 % air, without water, for 10 s); fluoride + laser group (F + L), and control group (C). All specimens were demineralized for 10 days in a 0.2 M acetate buffer solution, and the calcium content were subsequently determined with atomic absorption spectrometry. There were significant differences between the calcium content of F + L and F group in comparison to control group. The least concentration of calcium was seen in F + L group, and the most value was observed in C group. Combination of Er, Cr:YSGG laser with fluoride and fluoride alone decreased enamel solubility significantly more than laser alone. In addition, combination of laser and fluoride leads to less consumption of fluoride amount. And patients can use it at the beginning of treatment instead of daily use of fluoride. So we suggest using it in preventing enamel demineralization around orthodontic brackets. PMID:23624699

Fekrazad, Reza; Ebrahimpour, Leila

2013-04-30

282

Sensitivity of microarray based immunoassays using surface-attached hydrogels.  

PubMed

A promising pathway to improve on the sensitivity of protein microarrays is to immobilize the capture antibodies in a three dimensional hydrogel matrix. We describe a simple method based on printing of an aqueous protein solution containing a photosensitive polymer and the capture antibody onto a plastic chip surface. During short UV-exposure photocrosslinking occurs, which leads to formation of a hydrogel, which is simultaneously bound to the substrate surface. In the same reaction the antibody becomes covalently attached to the forming hydrogel. As the capture antibodies are immobilized in the three-dimensional hydrogel microstructures, high fluorescence intensities can be obtained. The chip system is designed such, that non-specific protein adsorption is strongly prevented. Thus, the background fluorescence is strongly reduced and very high signal-to-background ratios are obtained (SBR>6 for c(BSA)=1 pM; SBR>100 for c(BSA)>100 pM). The kinetics of antigen binding to the arrayed antibodies can be used to determine the concentration of a specific protein (for example the tumor marker ?2-microglobulin) in solution for a broad range of analyte concentrations. By varying size and composition of the protein-filled hydrogel microstructures as well as adjusting the extent of labeling it is possible to easily adapt the surface concentration of the probe molecules such that the fluorescence signal intensity is tuned to the prevalence of the protein in the analyte. As a consequence, the signal tuning allows to analyze solutions, which contain both proteins with high (here: upper mg mL(-1) range) and with very low concentrations (here: lower ?g mL(-1) range). This way quantitative analysis with an exceptionally large dynamic range can be performed. PMID:23684467

Moschallski, Meike; Evers, Andreas; Brandstetter, Thomas; Rühe, Jürgen

2013-06-01

283

A glucose biosensor based on surface active maghemite nanoparticles.  

PubMed

A simple carbon paste (CP) electrode, modified with novel maghemite (?-Fe2O3) nanoparticles, called SAMNs (surface active maghemite nanoparticles) and characterized by a mean diameter of about 10nm, has been developed. The electrode catalyzes the electro-reduction of hydrogen peroxide at low applied potentials (-0.1 V vs SCE). In order to improve the electrocatalytic properties of the modified electrode an ionic liquid, namely 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), was introduced. At -0.1 V, the sensitivity of the SAMN-BMIM-PF6-CP electrode was 206.51 nA ?M(-1)cm(-2), with a detection limit (S/N=3) of 0.8 ?M, in the 0-1.5mM H2O2 concentration range. Furthermore, glucose oxidase was immobilized on the surface of maghemite nanoparticles as a monomolecular layer, by a bridge constituted of rhodamine B isothiocyanate, leading to a fluorescent, magnetic drivable nanocatalyst, containing 10 ± 2 enzyme molecules per nanoparticle. The resulting enzyme electrode presents a linear calibration curve toward glucose in solution in the concentration range of 0-1.5mM glucose, characterized by a sensitivity of 45.85 nA ?M(-1)cm(-2) and a detection limit (S/N=3) of 0.9 ?M. The storage stability of the system was evaluated and a half-life of 2 months was calculated, if the electrode is stored at 4°C in buffer. The present work demonstrates the feasibility of these surface active maghemite nanoparticles as efficient hydrogen peroxide electro-catalyst, which can be easily coupled to hydrogen peroxide producing enzymes in order to develop oxidase based reagentless biosensor devices. PMID:23454337

Baratella, Davide; Magro, Massimiliano; Sinigaglia, Giulietta; Zboril, Radek; Salviulo, Gabriella; Vianello, Fabio

2013-07-15

284

Evaluation of Shear Bond Strength of Orthodontic Brackets Bonded with Nano-Filled Composites  

PubMed Central

Objectives: The purpose of this study was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded with two types of nano-composites in comparison to a conventional orthodontic composite. Materials and Methods: Sixty extracted human first premolars were randomly divided into 3 groups each containing 20 teeth. In group I, a conventional orthodontic composite (Transbond XT) was used to bond the brackets, while two nano-composites (Filtek TM Supreme XT and AELITE Aesthetic Enamel) were used in groups II and III respectively. The teeth were stored in distilled water at 37°C for 24 hours, thermocycled in distilled water and debonded with a universal testing machine at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was also evaluated using a stereomicroscope. Results: AELITE Aesthetic Enamel nano-composite revealed a SBS value of 8.44±2.09 MPa, which was higher than Transbond XT (6.91±2.13) and Filtek TM Supreme XT (6.04±2.01). Statistical analysis revealed a significant difference between groups II and III (P < 0.05). No significant difference was found between groups I and III, and between groups I and II (P > 0.05). Evaluation of ARI showed that Transbond XT left fewer adhesive remains on teeth after debonding. Conclusion: Results of this study indicate that the aforementioned nano-composites can be successfully used for bonding orthodontic brackets.

Chalipa, Javad; Akhondi, Mohammad Sadegh Ahmad; Arab, Sepideh; Kharrazifard, Mohammad Javad; Ahmadyar, Maryam

2013-01-01

285

Sensing-Applications of Surface-Based Single Vesicle Arrays  

PubMed Central

A single lipid vesicle can be regarded as an autonomous ultra-miniaturised 3D biomimetic “scaffold” (Ø ? 13 nm) ideally suited for reconstitution and interrogation of biochemical processes. The enclosing lipid bilayer membrane of a vesicle can be applied for studying binding (protein/lipid or receptor/ligand interactions) or transmembrane events (membrane permeability or ion channel activation) while the aqueous vesicle lumen can be used for confining few or single macromolecules and probe, e.g., protein folding, catalytic pathways of enzymes or more complex biochemical reactions, such as signal transduction cascades. Immobilisation (arraying) of single vesicles on a solid support is an extremely useful technique that allows detailed characterisation of vesicle preparations using surface sensitive techniques, in particular fluorescence microscopy. Surface-based single vesicle arrays allow a plethora of prototypic sensing applications in a high throughput format with high spatial and high temporal resolution. In this review we present a series of applications of single vesicle arrays for screening/sensing of: membrane curvature dependent protein-lipid interactions, bilayer tension, reactions triggered in the vesicle lumen, the activity of transmembrane protein channels and biological membrane fusion reactions.

Christensen, Sune M.; Stamou, Dimitrios G.

2010-01-01

286

Surface chemistry to minimize fouling from blood-based fluids.  

PubMed

Upon contact with bodily fluids/tissues, exogenous materials spontaneously develop a layer of proteins on their surface. In the case of biomedical implants and equipment, biological processes with deleterious effects may ensue. For biosensing platforms, it is synonymous with an overwhelming background signal that prevents the detection/quantification of target analytes present in considerably lower concentrations. To address this ubiquitous problem, tremendous efforts have been dedicated over the years to engineer protein-resistant coatings. There is now extensive literature available on stealth organic adlayers able to minimize fouling down to a few ng cm(-2), however from technologically irrelevant single-protein buffered solutions. Unfortunately, few coatings have been reported to present such level of performance when exposed to highly complex proteinaceous, real-world media such as blood serum and plasma, even diluted. Herein, we concisely review the surface chemistry developed to date to minimize fouling from these considerably more challenging blood-based fluids. Adsorption dynamics is also discussed. PMID:22772072

Blaszykowski, Christophe; Sheikh, Sonia; Thompson, Michael

2012-09-01

287

Sensing-applications of surface-based single vesicle arrays.  

PubMed

A single lipid vesicle can be regarded as an autonomous ultra-miniaturised 3D biomimetic "scaffold" (Ø?13 nm) ideally suited for reconstitution and interrogation of biochemical processes. The enclosing lipid bilayer membrane of a vesicle can be applied for studying binding (protein/lipid or receptor/ligand interactions) or transmembrane events (membrane permeability or ion channel activation) while the aqueous vesicle lumen can be used for confining few or single macromolecules and probe, e.g., protein folding, catalytic pathways of enzymes or more complex biochemical reactions, such as signal transduction cascades. Immobilisation (arraying) of single vesicles on a solid support is an extremely useful technique that allows detailed characterisation of vesicle preparations using surface sensitive techniques, in particular fluorescence microscopy. Surface-based single vesicle arrays allow a plethora of prototypic sensing applications in a high throughput format with high spatial and high temporal resolution. In this review we present a series of applications of single vesicle arrays for screening/sensing of: membrane curvature dependent protein-lipid interactions, bilayer tension, reactions triggered in the vesicle lumen, the activity of transmembrane protein channels and biological membrane fusion reactions. PMID:22163531

Christensen, Sune M; Stamou, Dimitrios G

2010-01-01

288

Infrared transparent frequency selective surface based on metallic meshes  

NASA Astrophysics Data System (ADS)

This paper presents an infrared transparent frequency selective surface (ITFSS) based on metallic meshes. In this ITFSS structure, periodic cross-slot units are integrated on square metallic meshes empowered by coating and UV-lithography. A matching condition is proposed to avoid the distortion of units. Experimental results show that this ITFSS possesses a good transmittance of 80% in the infrared band of 3-5 ?m, and also a stable band-pass behavior at the resonance frequency of 36.4 GHz with transmittance of -0.56 dB. Theoretical simulations about the ITFSS diffractive characteristics and frequency responses are also investigated. The novel ITFSS will attract renewed interest and be exploited for applications in various fields.

Yu, Miao; Xu, Nianxi; Liu, Hai; Gao, Jinsong

2014-02-01

289

Quantifying modern biomes based on surface pollen data in China  

NASA Astrophysics Data System (ADS)

Large-scale surface pollen records and reconstructions of modern biomes are a necessary prerequisite for the understanding of past vegetation and climate changes, especially in large countries such as China which is subject to a variety of climatic regimes and has experienced long-term intensive anthropogenic disturbances. An updated surface pollen data set consisting of 2324 samples and 737 taxa is used to reconstruct biome distribution in China according to a newly established and well-tested global classification of plant functional types, based on the regional assessment of pollen taxa and the quantitative pollen-biome assignment method of biomization. Nineteen reconstructed types of biome present a reasonable reflection of the latitudinal and altitudinal distributions of modern vegetation in China. Incorrect assignment has previously occurred in some biomes, for example among the cold and cool temperate coniferous forests and mixed forest, among warm-temperate evergreen forest, mixed forest and tropical forests, and among temperate shrubland, grassland, desert and tundra biomes. Mega-biomes, grouped for the same bioclimatic zones, result in a better reconstruction than the nineteen separate biome types. The correct assignments increased from 68.8% to 80.6%. However, comparison of pollen-based biome reconstructions to climate-driven vegetation simulations performed using the global vegetation model BIOME4 indicates a low correlation rate (only 24.8%), suggesting that more needs to be done to combine palaeoenvironmental data with model simulations of past vegetation changes. The misassignment of surface pollen to modern biomes usually occurs in areas which have similar bioclimatic features and vegetation types and for biomes which share the same plant functional types. These mis-matches often occur in mountainous regions where transitional vegetation zones occur on hill slopes at mid-altitudes. Our new modern biome reconstruction for China is more robust and reliable; however continued analysis of pollen records is required in the remote areas of western China and the Tibetan Plateau, as well as in regions of central and eastern China which have suffered from high levels of anthropogenic activity. This type of anthropogenic biome reconstruction presents a new challenge.

Chen, Yu; Ni, Jian; Herzschuh, Ulrike

2010-12-01

290

Highly antibacterial activity of N-doped TiO2 thin films coated on stainless steel brackets under visible light irradiation  

NASA Astrophysics Data System (ADS)

In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO2 thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi; Liu, Bin; Cao, Baocheng

2014-08-01

291

Computer Vision Based Non-contact Surface Roughness Assessment Using Wavelet Transform and Response Surface Methodology  

Microsoft Academic Search

This paper describes a new non-contact measurement approach in characterizing manufactured surfaces. Computer vision is applied to capture digital images of three types of anisotropic steel specimen surfaces from shaping, grinding, and polishing processes. Multiresolution wavelet decomposition is used to obtain signatures of surface profiles from the digital images. Relationships between these signatures and surface roughness parameters (Ra and Rq)

Shing I. Chang; Jayakumar S. Ravathur

2005-01-01

292

Implementation of Frictional Contact Conditions in Surface to Surface, Mortar Based Computational Frameworks  

SciTech Connect

A number of recent works have established the mortar technique as an accurate and robust spatial discretization method for contact problems in computational solid mechanics. Since methods based on this idea rely on an integral, non-local representation of the contact operators, their formulation is somewhat more involved than is true for more traditional ''point to surface'' contact algorithms; in particular, the integral projections have nontrivial linearizations in the fully large deformation context. In this work, we concentrate on another aspect of formulations of this type--definition and implementation of frictional contact operators within the mortar contact framework. Issues associated with frame indifference of frictional tractions and kinematics are discussed, and a numerical demonstration of the technique is given.

Laursen, T A; Yang, B; Puso, M A

2004-04-01

293

Surface plasmon resonance-based immunoassay for human fetuin A.  

PubMed

This article describes a highly-sensitive surface plasmon resonance (SPR)-based immunoassay (IA) for human fetuin A (HFA), a specific biomarker for atherosclerosis and hepatocellular carcinoma. The assay is based on a novel immobilization procedure that simply involves the dilution of an anti-HFA capture antibody (Ab) in 1% (v/v) 3-aminopropyltriethoxysilane (APTES), followed by its dispensing on a KOH-treated gold (Au)-coated SPR chip and incubation for 30 min. The developed SPR IA detected 0.3-20 ng mL(-1) of HFA with a limit of detection and sensitivity of 0.7 ng mL(-1) and 1 ng mL(-1), respectively. The highly-simplified Ab immobilization procedure is also 5-fold more rapid than conventional procedures. It leads to the leach-proof binding of the capture Ab, which means that the developed SPR IA is highly cost-effective, as the Ab-bound SPR chip could be reused for many repeated HFA IAs after regeneration with 10 mM glycine-HCl, pH 2.0. The Ab-bound SPR chip, stored at 4 °C, lost only 18% of its original activity after 4 months. For the detection of HFA spiked in diluted human whole blood and plasma, the results obtained by the developed SPR IA agreed well with the commercial HFA sandwich ELISA. PMID:24652275

Vashist, S K; Schneider, E M; Luong, J H T

2014-05-01

294

Surface plasmon resonance based fiber optic glucose biosensor  

NASA Astrophysics Data System (ADS)

A surface plasmon resonance (SPR) based fiber optic biosensor has been fabricated and characterized for the detection of blood glucose. Optical fiber sensor was fabricated by first coating a 50 nm thick gold film on the bare core of optical fiber and then immobilizing glucose oxidase (GOx) over it. Aqueous glucose solutions of different concentrations were prepared. To mimic the blood glucose levels, the concentration of glucose solutions were kept equal to that in human blood. The refractive indices of these sample solutions were equal to that of water up to third decimal place. SPR spectra for the sensor were recorded for these glucose solutions. When the glucose comes in contact to glucose oxidase, chemical reactions take place and as a result, the refractive index of the immobilized GOx film changes, giving rise to a shift in the resonance wavelength. Unlike electrochemical sensors, the present sensor is based on optics and can be miniaturized because of optical fiber. The present study provides a different approach for blood glucose sensing and may be commercialized after optimization of certain parameters.

Srivastava, Sachin K.; Verma, Roli; Gupta, Banshi D.

2012-01-01

295

Satellite-based estimates of Antarctic surface meltwater fluxes  

NASA Astrophysics Data System (ADS)

study generates novel satellite-derived estimates of Antarctic-wide annual (1999-2009) surface meltwater production using an empirical relationship between radar backscatter from the QuikSCAT (QSCAT) satellite and melt calculated from in situ energy balance observations. The resulting QSCAT-derived melt fluxes significantly agree with output from the regional climate model RACMO2.1 and with independent ground-based observations. The high-resolution (4.45 km) QSCAT-based melt fluxes uniquely detect interannually persistent and intense melt (>400 mm water equivalent (w.e.) year-1) on interior Larsen C Ice Shelf that is not simulated by RACMO2.1. This supports a growing understanding of the importance of a föhn effect in this region and quantifies the resulting locally enhanced melting that is spatially consistent with recently observed Larsen C thinning. These new results highlight important cryosphere-climate interactions and processes that are presently not fully captured by the coarser-resolution (27 km) regional climate model.

Trusel, Luke D.; Frey, Karen E.; Das, Sarah B.; Munneke, Peter Kuipers; Broeke, Michiel R.

2013-12-01

296

The Cbf5-Nop10 Complex is a Molecular Bracket that Organizes Box H/ACA RNPs  

SciTech Connect

Box H/ACA ribonucleoprotein particles (RNPs) catalyze RNA pseudouridylation and direct processing of ribosomal RNA, and are essential architectural components of vertebrate telomerases. H/ACA RNPs comprise four proteins and a multihelical RNA. Two proteins, Cbf5 and Nop10, suffice for basal enzymatic activity in an archaeal in vitro system. We now report their cocrystal structure at 1.95-A resolution. We find that archaeal Cbf5 can assemble with yeast Nop10 and with human telomerase RNA, consistent with the high sequence identity of the RNP componenets between archaea and eukarya. Thus, the Cbf5-Nop10 architecture is phylogenetically conserved. The structure shows how Nop10 buttresses the active site of Cbf5, and it reveals two basic troughs that bidirectionally extend the active site cleft. Mutagenesis results implicate an adjacent basic patch in RNA binding. This tripartite RNA-binding surface may function as a molecular bracket that organizes the multihelical H/ACA and telomerase RNAs.

Hamma, Tomoko; Reichow, Steve L.; Varani, Gabriele; Ferre-D'Amare, Adrian R.

2005-12-01

297

The Cbf5-Nop10 complex is a molecular bracket that organizes box H/ACA RNPs.  

PubMed

Box H/ACA ribonucleoprotein particles (RNPs) catalyze RNA pseudouridylation and direct processing of ribosomal RNA, and are essential architectural components of vertebrate telomerases. H/ACA RNPs comprise four proteins and a multihelical RNA. Two proteins, Cbf5 and Nop10, suffice for basal enzymatic activity in an archaeal in vitro system. We now report their cocrystal structure at 1.95-A resolution. We find that archaeal Cbf5 can assemble with yeast Nop10 and with human telomerase RNA, consistent with the high sequence identity of the RNP components between archaea and eukarya. Thus, the Cbf5-Nop10 architecture is phylogenetically conserved. The structure shows how Nop10 buttresses the active site of Cbf5, and it reveals two basic troughs that bidirectionally extend the active site cleft. Mutagenesis results implicate an adjacent basic patch in RNA binding. This tripartite RNA-binding surface may function as a molecular bracket that organizes the multihelical H/ACA and telomerase RNAs. PMID:16286935

Hamma, Tomoko; Reichow, Steve L; Varani, Gabriele; Ferré-D'Amaré, Adrian R

2005-12-01

298

The surface of Mercury from ground-based astronomical observations  

NASA Astrophysics Data System (ADS)

Recent ground-based astronomical short-exposure observations of Mercury have yielded more than 50000 electronic pictures of the planet at different phases and different positions relative to the Earth. The work was fulfilled in several observatories. The use of available and newly developed processing methods applied to large volumes of electronic frames allowed the images of a considerable portion of Mercury’s surface to be synthesized. We present the images of the 90° 180°W, 215° 280°W, and 50° 90°W sectors containing, among others, the longitudes not covered by spacecraft imaging. Along with the listed images, we present the results of recent observations of Mercury carried out on November 20 24, 2006 during the morning elongation at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) (Nizhnii Arkhyz, Karachai-Circassia, the Caucasus). The 265° 350°W longitude sector of Mercury was observed. The observations were made under good weather conditions. Among the main tasks of the new observations was obtaining a complete view of the S Basin. Previously, this basin had been investigated in fragments only by the actual solar illumination conditions. During the period of November 20 24, 2006, the S Basin was on the sunlit side of the planet. The complete image of the basin was obtained from the processing of a large number of electronic frames. The appearance of the S Basin is compared with the data on its relief acquired with radar methods. In this longitude sector, a number of other unusual surface features were found; among them, are a huge “Medallion” crater and other formations. The results considered in the present and earlier published studies are compared with the Mariner 10 data (1974 1975) and with the data received from the Messenger spacecraft during its first flyby of the planet (January 2008).

Ksanfomality, L. V.

2008-12-01

299

Vacuum-based surface modification of organic and metallic substrates  

Microsoft Academic Search

Surface physico-chemical properties play an important role in the development and performance of materials in different applications. Consequently, understanding the chemical and physical processes involved during surface modification strategies is of great scientific and technological importance. This dissertation presents results from the surface modification of polymers, organic films and metallic substrates with reactive species, with the intent of simulating important

Jessica Torres

2004-01-01

300

Molding reflection from metamaterials based on magnetic surface plasmons  

Microsoft Academic Search

We demonstrate a dramatically molded reflection of an electromagnetic (EM) wave from the magnetic metamaterial (MM) surface occurring near the magnetic surface plasmon (MSP) resonance. It is found that on one side of the source the reflected field nearly cancels the incoming field, giving rise to a shadowy region near the MM surface, while on the other side the reflected

Shiyang Liu; Wanli Lu; Zhifang Lin; S. T. Chui

2011-01-01

301

Intelligent observer-based road surface condition detection and identification  

Microsoft Academic Search

Road surface condition is greatly dependent on the surface's friction coefficient. The abrupt change of the coefficient results in variation of wheel slip which likely leads to vehicle instability. Although the vehicle on-board sensors can measure the vehicle's velocities and yaw rate, the measurements, often containing noise and drift, are limited to the surface that the vehicle is engaged. In

Paul P. Lin; Maosheng Ye; Kuo-Ming Lee

2008-01-01

302

High-temperature molecular magnets based on cyanovanadate building blocks: Spontaneous magnetization at 230 K  

Microsoft Academic Search

The molecular-based magnetic materials Cs2Mn(sup II) (left bracket) V(sup II)(CN)6 (right bracket) (1) and (Et4N)(0.5)Mn(1.25)- (left bracket) V(CN)5 (right bracket) center-dot 2H2O (2) (where Et is ethyl) were prepared by the addition of manganese(II) triflate to aqueous solutions of the hexacyanovanadate(II) ion at 0 C. Whereas 1 crystallizes in a face-centered cubic lattice, 2 crystallizes in a noncubic space group.

William R. Entley; Gregory S. Girolami

1995-01-01

303

Reproducibility of UAV-based earth surface topography based on structure-from-motion algorithms.  

NASA Astrophysics Data System (ADS)

A representation of the earth surface at very high spatial resolution is crucial to accurately map small geomorphic landforms with high precision. Very high resolution digital surface models (DSM) can then be used to quantify changes in earth surface topography over time, based on differencing of DSMs taken at various moments in time. However, it is compulsory to have both high accuracy for each topographic representation and consistency between measurements over time, as DSM differencing automatically leads to error propagation. This study investigates the reproducibility of reconstructions of earth surface topography based on structure-from-motion (SFM) algorithms. To this end, we equipped an eight-propeller drone with a standard reflex camera. This equipment can easily be deployed in the field, as it is a lightweight, low-cost system in comparison with classic aerial photo surveys and terrestrial or airborne LiDAR scanning. Four sets of aerial photographs were created for one test field. The sets of airphotos differ in focal length, and viewing angles, i.e. nadir view and ground-level view. In addition, the importance of the accuracy of ground control points for the construction of a georeferenced point cloud was assessed using two different GPS devices with horizontal accuracy at resp. the sub-meter and sub-decimeter level. Airphoto datasets were processed with SFM algorithm and the resulting point clouds were georeferenced. Then, the surface representations were compared with each other to assess the reproducibility of the earth surface topography. Finally, consistency between independent datasets is discussed.

Clapuyt, François; Vanacker, Veerle; Van Oost, Kristof

2014-05-01

304

Global surface-based cloud observation for ISCCP  

NASA Technical Reports Server (NTRS)

Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight. Ten years of nighttime weather observations from the northern hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6 degrees or from a partial moon at higher elevation, or twilight from the sun less than 9 degrees below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon. The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is now found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans far from the continents, particularly in summer. However, near noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night, by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a few regions; they are generally in better agreement if the moonlight criterion is imposed on the surface observations. Using the moonlight criterion, we have analyzed ten years (1982-1991) of surface weather observations over land and ocean, worldwide, for total cloud cover and for the frequency of occurrence of clear sky, fog and precipitation The global average cloud cover (average of day and night) is about 2% higher if we impose the moonlight criterion than if we use all observations. The difference is greater in winter than in summer, because of the fewer hours of darkness in the summer. The amplitude of the annual cycle of total cloud cover over the Arctic Ocean and at the South Pole is diminished by a few percent when the moonlight criterion is imposed. The average cloud cover for 1982-1991 is found to be 55% for northern hemisphere land, 53% for southern hemisphere land, 66% for northern hemisphere ocean, and 70% for southern hemisphere ocean, giving a global average of 64%. The global average for daytime is 64.6% for nighttime 63.3%.

1994-01-01

305

Root resorption, treatment time and extraction rate during orthodontic treatment with self-ligating and conventional brackets  

PubMed Central

Introduction This study determined the amount and severity of EARR (external apical root resorption) after orthodontic treatment with self-ligating (SL) and conventional (Non-SL) brackets. Differences regarding rate of extraction cases, appointments and treatment time were evaluated. Material and methods 213 patients with a mean age of 12.4?±?2.2 years were evaluated retrospectively. The treatments were performed with SL brackets (n?=?139, Smartclip, 3 M Unitek, USA) or Non-SL brackets (n?=?74, Victory Series, 3 M Unitek, USA). Measurements of the crown and root length of the incisors were taken using panoramic radiographs. Three-factor analysis of variance (ANOVA) was performed for an appliance effect. Results There was no difference between patients treated with Non-SL or SL brackets regarding the amount (in percentage) of EARR (Non-SL: 4.5?±?6.6 vs. SL: 3.0?±?5.6). Occurrence of severe EARR (sEARR) did also not differ between the two groups (Non-SL 0.5 vs. SL: 0.3). The percentage of patients with need of tooth extraction for treatment (Non SL: 8.1 vs. SL: 6.9) and the number of appointments (Non-SL: 12.4?±?3.4 vs. SL: 13.9?±?3.3) did not show any differences. The treatment time was shorter with Non-SL brackets (Non-SL: 18.1?±?5.3 vs. SL: 20.7?±?4.9 months). Conclusions This is the largest study showing that there is no difference in the amount of EARR, number of appointments and extraction rate between conventional and self-ligating brackets. For the first time we could demonstrate that occurrence of sEARR does not differ between the two types of brackets.

2014-01-01

306

Symbolic algorithms for the computation of Moshinsky brackets and nuclear matrix elements  

NASA Astrophysics Data System (ADS)

To facilitate the use of the extended nuclear shell model (NSM), a FERMI module for calculating some of its basic quantities in the framework of MAPLE is provided. The Moshinsky brackets, the matrix elements for several central and non-central interactions between nuclear two-particle states as well as their expansion in terms of Talmi integrals are easily given within a symbolic formulation. All of these quantities are available for interactive work. Program summaryTitle of program:Fermi Catalogue identifier:ADVO Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVO Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions:None Computer for which the program is designed and others on which is has been tested:All computers with a licence for the computer algebra package MAPLE [Maple is a registered trademark of Waterloo Maple Inc., produced by MapleSoft division of Waterloo Maple Inc.] Instalations:GSI-Darmstadt; University of Kassel (Germany) Operating systems or monitors under which the program has beentested: WindowsXP, Linux 2.4 Programming language used:MAPLE 8 and 9.5 from MapleSoft division of Waterloo Maple Inc. Memory required to execute with typical data:30 MB No. of lines in distributed program including test data etc.:5742 No. of bytes in distributed program including test data etc.:288 939 Distribution program:tar.gz Nature of the physical problem:In order to perform calculations within the nuclear shell model (NSM), a quick and reliable access to the nuclear matrix elements is required. These matrix elements, which arise from various types of forces among the nucleons, can be calculated using Moshinsky's transformation brackets between relative and center-of-mass coordinates [T.A. Brody, M. Moshinsky, Tables of Transformation Brackets, Monografias del Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 1960] and by the proper use of the nuclear states in different coupling notations. Method of solution:Moshinsky's transformation brackets as well as two-nucleon matrix elements are provided within the framework of MAPLE. The transformation brackets are evaluated recursively for a given number of shells and utilized for the computation of the two-particle matrix elements for different coupling schemes and interactions. Moreover, a simple notation has been introduced to handle the two-particle nuclear states in ll-, LSJ-, and jj-coupling, both in the center-of-well and the relative and center-of-mass coordinates. Restrictions onto the complexity of the problem:The program supports in principle an arbitrary number of shell states with the only limitation given by the computer resources themselves. Typically, the time requirements for the recursive computation of the Moshinsky brackets and matrix elements increase rapidly with the number of the allowed shell states but can be reduced significantly by the pre-calculation of the transformation brackets. Unusual features of the program:Moshinsky brackets are computed and provided in either numeric, algebraic or some symbolic form. In addition, the two-particle matrix elements are calculated for a scalar potential, spin-orbit coupling and tensorial forces, both in floating-point and algebraic notation. All two-particle matrix elements are expressed in terms of the Talmi integrals but can be evaluated also explicitly for several predefined types of the interaction. To simplify the handling of the program, a short but very powerful notation has been introduced which help the user to deal with the two-particle states in various coupling notations. The main commands of the current version of the program are described in detail in Appendix B. Typical running time:The computation of all Moshinsky brackets in floating-point notation, up to ?=6, takes about 5 s at a 2.26 GHz Intel Pentium IIII processor with 512 MB; in algebraic form, the same computations take about 13 s. Similarly, the computation of these brackets up to ?=10 requires in numeric and algebraic form about 5 and 15 min, respectively. Once the

Ursescu, D.; Tomaselli, M.; Kuehl, T.; Fritzsche, S.

2005-12-01

307

FBG hydrogen sensors based on surface plasmon resonance interaction  

NASA Astrophysics Data System (ADS)

Many different types of fiber optic hydrogen gas sensors have been used to detect hydrogen concentration. Almost invariably these sensors, as well as the electrical hydrogen sensors, use palladium as the gas-sensitive layer by detecting its electrical and optical properties change, when it exposed to hydrogen. However the sensibility of them is poor and the minimum hydrogen detecting level is still very high. Fiber Bragg gratings (FBG) control over the properties of light propagating within the fiber. A change of the effective refractive index of grating period caused by the surrounding environment will cause a shift in the reflective Bragg wavelength. The totally different principle makes FBG with good sensing characters. In addition, FBG has a built-in self-referencing capability and can be multiplexed along a single fiber. Here a new method is put forward to detect the hydrogen concentration by FBG. The working principle of FBG hydrogen sensor is based on surface plasmon resonance. Fiber is firstly side polished in the FBG region to enable evanescent wave interaction. Experiment showed that this method is very sensitive, as low as 0.1% (1000ppm) of hydrogen concentration can be detected and the response time is less then 5 seconds.

Sun, Yan; Yang, Minghong; Wang, Bingbing; Wei, He

2009-08-01

308

Gis-Based Surface Analysis of Archaeological Finds  

NASA Astrophysics Data System (ADS)

The international research project HiMAT (History of Mining Activities in the Tyrol and adjacent areas) is dedicated to the study of mining history in the Eastern Alps by various scientific disciplines. The aim of this program is the analysis of the mining activities' impacts on environment and human societies. Unfortunately, there is only a limited number of specific regions (e.g. Mitterberg) to offer possibilities to investigate the former mining expansions. Within this multidisciplinary project, the archaeological sites and finds are analyzed by the Surveying and Geoinformation Unit at the University of Innsbruck. This paper shows data fusion of different surveying and post-processing methods to achieve a photo-realistic digital 3D model of one of these most important finds, the Bronze Age sluice box from the Mitterberg. The applied workflow consists of four steps: 1. Point cloud processing, 2. Meshing of the point clouds and editing of the models, 3. Image orientation, bundle and image adjustment, 4. Model texturing. In addition, a short range laser scanning survey was organized before the conservation process of this wooden find. More accurate research opportunities were offered after this detailed documentation of the sluice box, for example the reconstruction of the broken parts and the surface analysis of this archaeological object were implemented using these high-resolution datasets. In conclusion, various unperceived patterns of the wooden boards were visualized by the GIS-based tool marks investigation.

Kovács, K.; Hanke, K.; Moser, M.

2011-09-01

309

Ground Based Interferometric Radar for Surface Monitoring Applications  

NASA Astrophysics Data System (ADS)

Ground based interferometric radar (GBIR) measurements may be desirable for a number of surface deformation monitoring applications in the earth sciences. The University of Missouri (MU) GBIR system is highly portable, which helps facilitate rapid deployment to sites of interest. The MU GBIR has demonstrated millimeter and better sensitivity to deformation. In addition, the MU GBIR can be removed and re-positioned at the same point with geodetic-grade precision for repeat and long-term surveys. The MU GBIR's high portability and fast imaging capabilities allow rapid surveying scans about every 20 seconds when deployed. Near real time C-band and Ku-band imagery may be formed on site for initial quick looks. Imagery data may be further enhanced by polarimetric calibration, radiometric calibration, and time-series analysis. Over the 2012 and 2013 field seasons, the MU GBIR has collected measurements from multiple locations such as a glacier in Greenland, a canyon in Colorado, and several dams in Kansas and Missouri. Study results and additional progress will be presented. These projects are sponsored by grants from the University of Missouri Research Board and the National Science Foundation.

Legarsky, J. J.; Gomez, F. G.; Rosenblad, B.; Loehr, E.; Gilliam, J.; Panigrahi, D.; Held, B.; Gurnani, G.

2013-12-01

310

Long-term changes in Arctic surface-based inverions  

NASA Astrophysics Data System (ADS)

Surface-based inversions (SBI) are a common feature of the atmospheric boundary layer in the Arctic and play a significant role in processes such as vertical mixing of energy, pollutants, cloud formation etc. Recent studies have linked changes in SBI characteristics to some key aspects of polar climate change, such as, variability of sea ice and snowmelt. This study investigates changes in SBI behavior in the Arctic during the past five decades using radiosonde observations, reanalysis data (ERA40) and simulations by two state-of-the-art climate models (NCAR's CAM3 and NOAA/GFDL AM3). Changes in radiosonde observational methods, particularly changes in sounding vertical resolution, introduce artificial changes in radiosonde data that trend estimates. SBI intensity and depth are particularly sensitive to this problem, but SBI frequency of occurrence is more robust. We report observed SBI frequency trends and compare these model simulations. SBI depth and intensity changes over shorter periods, with more homogeneous observations, are also presented.

Zhang, Y.; Seidel, D. J.; Golaz, J.; Deser, C.; Tomas, R. A.

2010-12-01

311

An integrated software suite for surface-based analyses of cerebral cortex  

NASA Technical Reports Server (NTRS)

The authors describe and illustrate an integrated trio of software programs for carrying out surface-based analyses of cerebral cortex. The first component of this trio, SureFit (Surface Reconstruction by Filtering and Intensity Transformations), is used primarily for cortical segmentation, volume visualization, surface generation, and the mapping of functional neuroimaging data onto surfaces. The second component, Caret (Computerized Anatomical Reconstruction and Editing Tool Kit), provides a wide range of surface visualization and analysis options as well as capabilities for surface flattening, surface-based deformation, and other surface manipulations. The third component, SuMS (Surface Management System), is a database and associated user interface for surface-related data. It provides for efficient insertion, searching, and extraction of surface and volume data from the database.

Van Essen, D. C.; Drury, H. A.; Dickson, J.; Harwell, J.; Hanlon, D.; Anderson, C. H.

2001-01-01

312

Evaluation of stresses developed in different bracket-cement-enamel systems using finite element analysis with in vitro bond strength tests  

PubMed Central

Background The purpose of this study was to determine the bond strength of different orthodontic bracket materials (ceramic, stainless steel, and titanium) as well as stresses developed in bracket-cement-enamel systems using finite element (FE) analysis. Methods One hundred and thirty-five extracted human caries-free upper central incisors were divided into three groups (n?=?45/group) according to the type of orthodontic bracket materials (stainless steel, ceramic, and titanium). Each group was further subdivided into three subgroups (n?=?15/group) according to the bond strength test loading mode (shear short side, shear long side, and tensile). After debonding, the fractured specimen was examined, and the adhesive remnant index (ARI) was determined. FE analysis models analyzed the stress distribution within the cement and enamel. Bond strengths were analyzed using ANOVA and Tukey's test, and the ARI scores were analyzed using chi-square (?2) test. Results Shear loading at the short side of the bracket resulted in the highest bond strength and lowest maximum principal stress both on cement and enamel compared with the other loading modes (P?brackets presented with higher bond strength and lower maximum principal stress than metallic brackets (P?brackets (?2?=?64.852, P?brackets and the selection of orthodontic bracket materials affect the bond strength and stresses developed both on cement and enamel.

2014-01-01

313

Automatic vertebral identification using surface-based registration  

NASA Astrophysics Data System (ADS)

This work introduces an enhancement to currently existing methods of intra-operative vertebral registration by allowing the portion of the spinal column surface that correctly matches a set of physical vertebral points to be automatically selected from several possible choices. Automatic selection is made possible by the shape variations that exist among lumbar vertebrae. In our experiments, we register vertebral points representing physical space to spinal column surfaces extracted from computed tomography images. The vertebral points are taken from the posterior elements of a single vertebra to represent the region of surgical interest. The surface is extracted using an improved version of the fully automatic marching cubes algorithm, which results in a triangulated surface that contains multiple vertebrae. We find the correct portion of the surface by registering the set of physical points to multiple surface areas, including all vertebral surfaces that potentially match the physical point set. We then compute the standard deviation of the surface error for the set of points registered to each vertebral surface that is a possible match, and the registration that corresponds to the lowest standard deviation designates the correct match. We have performed our current experiments on two plastic spine phantoms and one patient.

Herring, Jeannette L.; Dawant, Benoit M.

2000-06-01

314

Mutual Information-Based 3D Surface Matching with Applications to Face Recognition and Brain Mapping  

Microsoft Academic Search

Face recognition and many medical imaging applica- tions require the computation of dense correspondence vec- tor elds that match one surface with another. In brain imaging, surface-based registration is useful for tracking brain change, and for creating statistical shape models of anatomy. Based on surface correspondences, metrics can also be designed to measure differences in facial geome- try and expressions.

Yalin Wang; Ming-chang Chiang; Paul M. Thompson

2005-01-01

315

Venus surface investigation based on VIRTIS measurements on Venus Express  

NASA Astrophysics Data System (ADS)

The dense atmosphere of Venus prevented systematic studies of its surface at optical wavelengths in the past. The discovery of near infrared nightside atmospheric windows has opened a new challenge for detailed surface studies. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express is the first experiment collecting continuously nightside surface emission data from the planet. The observed high variability of measured signatures is mainly due to spatial variations of cloud optical depth and surface elevation. The investigation of surface properties requires a convergent approach of radiative transfer simulations and VIR- TIS data analyses. Therefore, a selection of orbits with well calibrated data over the northern hemisphere was performed for footprints that cover a maximum range of surface elevation variations. Radiative transfer calculations demonstrate that the conservative character of cloud multiple scattering below 2 µm and a strong dependence of radiance ratios on surface elevation in this spectral region allow the mapping of surface topography and a retrieval of the surface temperature. To the first order, the surface temperature is a function of ground elevation. Small deviations from this first order dependence have been identified that are possibly due to different surface materials. 1 Institut f¨r Planetologie, Westf¨lische Wilhelms-Universit¨t M¨nster, Wilhelm-Klemm-Str.10, u a a u 48129 M¨nster, Germany u 2 German PlaceNameAerospace PlaceTypeCenter (DLR), Remote Sensing Technology Institute, Dpt. Marine Remote Sensing, Rutherfordstrasse 2, 12489 CityplaceBerlin, countryregionGermany 3 German PlaceNameAerospace PlaceTypeCenter (DLR), Institute for Planetary Research, Rutherfordstrasse 2, 12489 CityplaceBerlin, country-regionGermany 4 LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 place Jules Janssen, e 92195 Meudon, France 5 INAF-IASF (Instituto di Astrofisica Spaziale e Fisica Cosmica), via Statedel Fosso del Cavaliere, 100 00133 placeplaceCityRome, placeItaly

Arnold, Gabriele; Haus, Rainer; Döhler, Wolfgang; Kappel, David; Piccioni, Giuseppe; Drossart, Pierre

316

Evaluation of different LED light-curing devices for bonding metallic orthodontic brackets.  

PubMed

The aim of this study was to assess the influence of different light-emitting diodes (LED) light-curing devices for bonding orthodontic brackets, using the shear bond strength and analysis of adhesive remnant index (ARI). Crowns from 60 bovine incisors received brackets bonded with Transbond XT. Specimens were divided into 4 groups (n=15) according to the light-curing procedures: HL = control, halogen light; OR = Ortholux LED; UL = Ultraled XP, and RD = Radii LED. All light-curing procedures were performed for 40 s. Shear bond strength test was evaluated using an universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test. The ARI scores were evaluated with a stereoscopic magnifying glass and analyzed statistically by Kruskal-Wallis test. A significance level of 5% was set for all analyses. Shear bond strength means in MPa and standard deviations were 9.82 (3.28), 12.70 (3.35), 9.04 (2.80) and 11.22 (2.36) for HL, OR, UL and RD, respectively. OR presented the highest shear bond strength mean value. HL differed significantly (p<0.05) from Groups OR and RD. However, these groups did not differ significantly from each other (p>0.05). Regarding the ARI scores, no statistically significant difference was observed (p>0.05) among the groups. In conclusion, Ortholux LED and Radii LED units provided the highest values of bracket adhesive strength. PMID:21915524

Pinto, Corina Maia de Souza; Ferreira, José Tarcísio Lima; Matsumoto, Mírian Aiko Nakane; Borsatto, Maria Cristina; Silva, Raquel Assed Bezerra da; Romano, Fábio Lourenço

2011-01-01

317

Contributions to a reliable hydrogen sensor based on surface plasmon surface resonance spectroscopy  

NASA Astrophysics Data System (ADS)

Hydrogen is being seen as a potentially inexhaustible, clean power supply. Direct hydrogen production and storage techniques that would eliminate carbon by-products and compete in cost are accelerated in R&D due to the recent sharp price increase of crude oil. But hydrogen is also linked with certain risks of use, namely the danger of explosions if mixed with air due to the very low energy needed for ignition and the possibility to diminish the ozone layer by undetected leaks. To reduce those risks efficient, sensitive and very early warning systems are needed. This paper will contribute to this challenge in adopting the optical method of Surface-Plasmon-Resonance (SPR) Spectroscopy for a sensitive detection of hydrogen concentrations well below the lower explosion limit. The technique of SPR performed with fiberoptics would in principle allow a remote control without any electrical contacts in the potential explosion zone. A thin palladium metal layer has been studied as sensing element. A simulation programme to find an optimum sensor design lead to the conclusion that an Otto-configuration is more advantageous under intended "real world" measurement conditions than a Kretschmann configuration. This could be experimentally verified. The very small air gap in the Otto-configuration could be successfully replaced by a several hundred nm thick intermediate layer of MgF 2 or SiO 2 to ease the fabrication of hydrogen sensor-chips based on glass slide substrates. It could be demonstrated that by a separate detection of the TM- and TE-polarized light fractions the TE-polarized beam could be used as a reference signal, since the TE-part does not excite surface plasmons and thus is not influenced by the presence of hydrogen. Choosing the measured TM/TE intensity ratio as the analytical signal a sensor-chip made from a BK7 glass slide with a 425 nm thick intermediate layer of SiO 2 and a sensing layer of 50 nm Pd on top allowed a drift-free, reliable and reversible determination of hydrogen concentrations up to about 10 vol.% in dry or humid air with a detection limit of 0.04 vol.% with response times of around 2 min.

Morjan, Martin; Züchner, Harald; Cammann, Karl

2009-06-01

318

Range Image Segmentation Based on Decomposition of Surface Normals  

Microsoft Academic Search

A method for segmenting range images into homo- geneous regions is presented. The resulting regions are either planar or smooth curved surfaces. Surface con- tinuity is estimated by inspecting the values of normal vector components, which are linearized in respect to angular changes, and scaled depth values. The x- and y-components of the normal vector, and the depth map are

Kari Pulli; Matti Pietikainen

319

Model-based deformable surface finding for medical images  

Microsoft Academic Search

Describes a new global shape parameterization for smoothly deformable three-dimensional (3-D) objects, such as those found in biomedical images, whose diversity and irregularity make them difficult to represent in terms of fixed features or parts. This representation is used for geometric surface matching to 3-D medical image data, such as from magnetic resonance imaging (MRI). The parameterization decomposes the surface

L. H. Staib; J. S. Duncan

1996-01-01

320

Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles  

NASA Astrophysics Data System (ADS)

A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al2O3 and Fe3O4, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

2014-06-01

321

The need for satellite based observations of global surface waters  

Microsoft Academic Search

River discharge as well as lake and wetland storage of water are critical elements of land surface hydrology, yet they are poorly observed globally and the prospects for improvement from in-situ networks are bleak. Considering this, our NASA Surface Water working group is focused on the following science and applications questions: (1) What are the observational and data assimilation requirements

D. Lettenmaier; D. Alsdorf; C. Vörösmarty; C. Birkett

2003-01-01

322

A classification of duct modes based on surface waves  

Microsoft Academic Search

For the relatively high frequencies relevant in a turbofan engine duct, the modes of a lined section may be classified in two categories: genuine acoustic 3D duct modes resulting from the finiteness of the duct geometry, and 2D surface waves that exist only near the wall surface in a way essentially independent of the rest of the duct. Per frequency

Sjoerd W. Rienstra

2003-01-01

323

Surface Reactions Studied by Synchrotron Based Photoelectron Spectroscopy  

SciTech Connect

The goal of this article is to illustrate the use of synchrotron radiation for investigating surface chemical reactions by photoelectron spectroscopy. A brief introduction and background information is followed by examples of layer resolved spectroscopy, oxidation and sulfidation of metallic, semiconducting and oxide surfaces.

Hrbek, J.

1998-11-03

324

Fast example-based surface texture synthesis via discrete optimization  

Microsoft Academic Search

We synthesize and animate general texture pat- terns over arbitrary 3D mesh surfaces. The animation is con- trolled by o w elds over the target mesh, and the texture can be arbitrary user input as long it satises the Markov- Random-Field assumptions. We achieve this by extending the texture optimization framework over 3D mesh surfaces. We propose an efcient discrete

Jianwei Han; Kun Zhou; Li-yi Wei; Minmin Gong; Hujun Bao; Xinming Zhang; Baining Guo

2006-01-01

325

Surface-based bedload transport relation for gravel rivers  

Microsoft Academic Search

Bedload transport in gravel-bed rivers is accomplished by means of the mobilization of grains exposed on the bed surface. This mobilization is due to the action of fluid forces on the exposed grains. Substrate particles can participate in the bedload only to the extent that local or global scour results in their exposure on the surface. It follows that a

G. Parker

1990-01-01

326

Flow condensation on copper-based nanotextured superhydrophobic surfaces.  

PubMed

Superhydrophobic surfaces have shown excellent ability to promote dropwise condensation with high droplet mobility, leading to enhanced surface thermal transport. To date, however, it is unclear how superhydrophobic surfaces would perform under the stringent flow condensation conditions of saturated vapor at high temperature, which can affect superhydrophobicity. Here, we investigate this issue employing "all-copper" superhydrophobic surfaces with controlled nanostructuring for minimal thermal resistance. Flow condensation tests performed with saturated vapor at a high temperature (110 °C) showed the condensing drops penetrate the surface texture (i.e., attain the Wenzel state with lower droplet mobility). At the same time, the vapor shear helped ameliorate the mobility and enhanced the thermal transport. At the high end of the examined vapor velocity range, a heat flux of ~600 kW m(-2) was measured at 10 K subcooling and 18 m s(-1) vapor velocity. This clearly highlights the excellent potential of a nanostructured superhydrophobic surface in flow condensation applications. The surfaces sustained dropwise condensation and vapor shear for five days, following which mechanical degradation caused a transition to filmwise condensation. Overall, our results underscore the need to investigate superhydrophobic surfaces under stringent and realistic flow condensation conditions before drawing conclusions regarding their performance in practically relevant condensation applications. PMID:23249322

Torresin, Daniele; Tiwari, Manish K; Del Col, Davide; Poulikakos, Dimos

2013-01-15

327

Rapid debonding of polycrystalline ceramic orthodontic brackets with an Er:YAG laser: an in vitro study.  

PubMed

The usefulness of erbium-doped yttrium aluminum garnet laser irradiation for debonding ceramic brackets is assessed using a single laser pulse. Damon Clear brackets were chosen for their 85 % transmission of 2.94 ?m radiation and were bonded to 20 human third molars using the Blugloo adhesive system. Laser parameters comprised of 600 mJ pulse energy with 800 ?s duration, 1.3 mm fiber tip. Light microscopy was used to assess Adhesive Remnant Index (ARI) scores, and scanning electron microscope (SEM) images were taken of the cross-section of the enamel-adhesive interface. Nineteen brackets (95 %) were successfully debonded with a single laser pulse, while one bracket (5 %) required eight pulses for debonding. For all teeth, the SEM analysis showed no signs of damage to the enamel, and ARI scores of three were observed, supporting the result that the laser effect is confined in the adhesive. The presented laser parameters are able to rapidly debond suitable brackets. The debonding mechanism was concluded to be thermomechanical ablation for single pulse debonding. PMID:23525867

Mundethu, Ambili Roselina; Gutknecht, Norbert; Franzen, Rene

2013-03-24

328

Liquid radiation detectors based on nanosilver surface plasmon resonance phenomena.  

PubMed

The rapid development of micro- and nanostructures containing silver nanoparticles is based on their unique physical properties. Despite the new applications of silver nanoparticles in nanomedicine are under heavy discussions, silver nanoparticles could be used in liquid radiation detectors thanks to the irradiation-induced surface plasmon resonance (SPR) phenomena observed in the colloidal solutions. Silver nitrate (1 mM AgNO(3)) and sodium citrate (1 wt% and 5 wt% C(6)H(5)O(7)Na(3)) were used as precursors for the fabrication of colloidal solutions. Prepared solutions were exposed to gamma-rays from a (60)Co gamma therapy unit 'Rokus-M' to varying absorbed doses, from 2 to 250 Gy. A UV/VIS/NIR spectrometer (Avantes-2048) was used for the measurement of the optical properties (absorbance) of the silver solutions. It was found that an initial absorbed dose of 2 Gy induced the formation of spherical silver nanoparticles as it was indicated in the absorbance spectrum of the solution, which had a well-pronounced absorption maximum at the wavelength of 410 nm. There is a potential to measure absorbed doses down to around 20 mGy. The SPR peaks at the wavelengths of 500-700 nm were found at the highest investigated doses >100 Gy, indicating the presence of silver nanorods. The colour of colloidal solutions ranged from pale yellow to green and was dependent on the absorbed dose. The investigation has shown that density, size and shape of synthesised silver nanoparticles are dependent on the absorbed dose and that shape transformations of the particles due to irradiation are possible. Application of colloidal solutions containing silver nanoparticles for dosimetric purposes is discussed on the basis of the obtained results. PMID:20159913

Puiso, Judita; Laurikaitiene, Jurgita; Adliene, Diana; Prosycevas, Igoris

2010-01-01

329

LTS Gradiometers Based-On Superconducting Imaging Surface Design  

SciTech Connect

Gradiometer-like devices can be built using a superconducting imaging surface design. Such devices behave similarly to conventional wire-wound gradiometers for nearby magnetic sources. A large gradiometer array can be built by placing SQUID magnetometers close to the surface of a large superconducting plane. The most attractive advantage of such a gradiometer array is the ability to change a baseline for all channels simultaneously by mechanically moving the superconducting imaging surface relative to the sensor array. This can easily be accomplished even when the gradiometer array is cold. We built, experimentally tested, and simulated both first- and second-order gradiometer-like devices with adjustable baseline using the superconducting imaging surface design. First-order radial gradiometer sensors were made by placing planar magnetometers parallel to and near the superconducting imaging surface. A second-order electronic gradiometer was realized by subtracting the output from two of the first-order gradiometers described above.

Matlachov, A.N.; Kraus, R.H., Jr.; Espy, M.A.

1999-06-21

330

Simultaneous Estimation of Sea Surface Temperature and Precipitable Water Based on MOS-1/VTIR Data.  

National Technical Information Service (NTIS)

In the retrieval of the precipitable water and the sea surface temperature simultaneously from the data of satellite observation based on the linearized radiative transfer equation, selection of the optimum initial guess values of sea surface temperature,...

S. Takasaki M. Matsumoto K. Tsuchiya

1990-01-01

331

Acid base properties of cyanobacterial surfaces. II: Silica as a chemical stressor influencing cell surface reactivity  

NASA Astrophysics Data System (ADS)

Bacteria grow in complex solutions where the adsorption of aqueous species and nucleation of mineral phases on the cell surface may interfere with membrane-dependent homeostatic functions. While previous investigations have provided evidence that bacteria may alter their surface chemical properties in response to environmental stimuli, to our knowledge no effort has been made to evaluate surface compositional changes resulting from non-nutritional chemical stresses within a quantitative framework applicable to surface complexation modeling. We consider here the influence of exposure to silica on cyanobacterial surface chemistry, particularly in light of the propensity for cyanobacteria to become silicified in geothermal environments. Using data modeled from over 50 potentiometric titrations of the unsheathed cyanobacterium Anabaena sp. strain PCC 7120, we find that both abiotic geochemical and biotic biochemical-assimilatory factors have important and different effects on cell surface chemistry. Changes in functional group distribution that resulted from growth by different nitrogen assimilation pathways were greatest in the absence of dissolved silica and less important in its presence. Furthermore, out of the three nitrogen assimilation pathways investigated, in terms of surface functional group distribution, nitrate-reducing cultures were least sensitive, and ammonium-assimilating cultures were most sensitive, to changes in media silica concentration. When functional group distributions were plotted as a function of silica concentration, it appears that, with higher silica concentrations, basic groups (p Ka > 7) increase in concentration relative to acidic groups (p Ka < 7), and the total ligand densities (on a per-weight basis) decreased. The results imply a decrease in both the magnitude and density of surface charge as the net result of growth at high silica concentrations. Thus, Anabaena sp. appears to actively respond to growth in silicifying solutions by altering its surface properties in a manner that is likely to be manifested in nature by facilitated surface attachment. We conclude that potentiometric titrations reveal a Gram-negative bacterial surface whose properties are dynamic with respect to both nutrient and geochemical stressors.

Lalonde, S. V.; Smith, D. S.; Owttrim, G. W.; Konhauser, K. O.

2008-03-01

332

Effects of acid and alkaline based surface preparations on spray deposited cerium based conversion coatings on Al 2024-T3  

Microsoft Academic Search

Cerium based conversion coatings were spray deposited on Al 2024-T3 and characterized to determine the effect of surface preparation on the deposition rate and surface morphology. It was found that activation of the panel using a 1-wt.% sulfuric acid solution increased the coating deposition rate compared to alkaline cleaning alone. Analysis of the surface morphology of the coatings showed that

W. Pinc; S. Geng; M. O’Keefe; W. Fahrenholtz; T. O’Keefe

2009-01-01

333

Surface engineering approaches to micropattern surfaces for cell-based assays  

Microsoft Academic Search

The ability to produce patterns of single or multiple cells through precise surface engineering of cell culture substrates has promoted the development of cellular bioassays that provide entirely new insights into the factors that control cell adhesion to material surfaces, cell proliferation, differentiation and molecular signaling pathways. The ability to control shape and spreading of attached cells and cell–cell contacts

Didier Falconnet; Gabor Csucs; H. Michelle Grandin; Marcus Textor

2006-01-01

334

What Role Do Surfaces Play in GB Models? A New-Generation of Surface-Generalized Born Model Based on a Novel Gaussian Surface for Biomolecules  

PubMed Central

We have developed a version of our surface generalized Born (SGB) model that employs a Gaussian surface, as opposed to the van der Waals surface used previously. The Gaussian surface is smooth and its properties are analytically differentiable with respect to the positions of atoms. A significant advantage of a solvent model based on this analytically differentiable surface is the availability of analytical gradients of the surface and solvation forces. An efficient and robust algorithm is designed to construct and triangulate the Gaussian surface for large biomolecules with arbitrary shapes, and to compute the various terms required for energy gradients. The Gaussian surface is shown to better mimic the boundary between the solute and solvent by properly addressing solvent accessibility, as is demonstrated by comparisons with standard Poisson–Boltzmann calculations for proteins of different sizes. These results also demonstrate that surface definition is a dominant contribution to differences between GB and PB calculations, especially if the system is large. Application of the new surface to prediction of long loop regions is presented, and significant improvement in the energetics is seen compared with results obtained using the van der Waals surface, even in the absence of optimized empirical correction terms that were used in the latter calculations.

YU, ZHIYUN; JACOBSON, MATTHEW P.; FRIESNER, RICHARD A.

2009-01-01

335

Physics-Based Subdivision Surface Modeling for Medical Imaging and Simulation  

Microsoft Academic Search

In this paper a physics-based dynamic subdivision surface model based on Catmull-Clark surfaces is introduced and a new technique for exact evaluation of the dynamic model parameters, such as mass, damping and stiffness matrices, and dynamic forces etc. is presented for the dynamic subdivision surface. A closed-form analytic formula for thin-plate energy of Catmull-Clark surfaces of arbitrary topology is derived,

Kaihuai Qin; Huawei Wang; Denggao Li; Ron Kikinis; Michael Halle

2001-01-01

336

Structural Surface of Mould Softness Abrasive Flow Precision Polishing Machining Method Based on VOF  

Microsoft Academic Search

Aiming to improve the surface roughness of precision mould structural surface in finish machining, a new mould structural surface no-tool precision polishing method based on softness abrasive flow was brought forward. Dynamical model of softness abrasive flow in bound flow oriented to mould structural surface precision machining was established based on liquid-solid two-phase flow coupling theory and a continuous media

Bo Tang; Shiming Ji; Dapeng Tan

2010-01-01

337

Superhydrophobic graphene-based materials: surface construction and functional applications.  

PubMed

Many naturally occurring surfaces have superhydrophobicity that fulfils their functional demands, which has inspired considerable interest to develop similar artificial superhydrophobic surfaces with a variety of functionalities. Graphene is an ideal candidate for functional superhydrophobic surfaces due to its exceptional physicochemical properties. The recent advances in this emerging field are summarized, including the wetting behavior of water on graphene and the formation of crumpling/nanoparticle/foam-induced hierarchical structures, with emphasis on fundamental understanding for related processes. The potential applications in energy, environmental remediation, and thermal management are also discussed. PMID:24089354

Chen, Zhongxin; Dong, Lei; Yang, Dong; Lu, Hongbin

2013-10-01

338

Surface treatment of silicate based glass: base Piranha treatment versus 193nm laser processing  

NASA Astrophysics Data System (ADS)

Contact angle measurements of water on pathology grade borosilicate glass microscope slides before and after base piranha treatment are compared to treatment with 193nm laser irradiation. 193nm irradiation in the presence of hydrogen was also explored. Within experimental resolution, the observed changes in contact angle as a result of treatment either with base Piranha solution or with laser processing are identical. The contact angle, a, in both cases is reduced from a = (27 +/- 6)º to a = (8 +/- 3)º with treatment. However, for the piranha base method, there is an observed reversal over time either fully recovering or partially recovering within hours. By contrast, with laser processed, the increased surface wettability is retained with no change for more than 15 hours. In all cases, surface functionalisation, as measured by contact angle, with (3-mercaptopropyl)trimethoxysilane (MPTS) is found to be largely independent of any processing. We conclude that the method of contact angle as a means for qualitatively asserting improvements in attachment is unjustified.

Canning, J.; Petermann, I.; Cook, K.

2012-01-01

339

Chemical sensors based on surface-confined dendrimers.  

National Technical Information Service (NTIS)

The use of dendrimers for preparing chemically sensitive interfaces for detecting volatile organic compounds (VOCs) using surface acoustic wave (SAW) device transducers is described. Specifically, the synthesis of the dendrimers and the means by which the...

H. Tokuhisa R. M. Crooks A. J. Ricco G. C. Osbourn

1997-01-01

340

Vacuum-based surface modification of organic and metallic substrates  

NASA Astrophysics Data System (ADS)

Surface physico-chemical properties play an important role in the development and performance of materials in different applications. Consequently, understanding the chemical and physical processes involved during surface modification strategies is of great scientific and technological importance. This dissertation presents results from the surface modification of polymers, organic films and metallic substrates with reactive species, with the intent of simulating important modification processes and elucidating surface property changes of materials under different environments. The reactions of thermally evaporated copper and titanium with halogenated polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) are used to contrast the interaction of metals with polymers. Results indicate that reactive metallization is thermodynamically favored when the metal-halogen bond strength is greater than the carbon-halogen bond strength. X-ray post-metallization treatment results in an increase in metal-halide bond formation due to the production of volatile halogen species in the polymer that react with the metallic overlayer. The reactions of atomic oxygen (AO) and atomic chlorine with polyethylene (PE) and self-assembled monolayers (SAMs) films were followed to ascertain the role of radical species during plasma-induced polymer surface modification. The reactions of AO with X-ray modified SAMs are initially the dominated by the incorporation of new oxygen containing functionality at the vacuum/film interface, leading to the production of volatile carbon containing species such as CO2 that erodes the hydrocarbon film. The reaction of atomic chlorine species with hydrocarbon SAMs, reveals that chlorination introduces C-Cl and C-Cl2 functionalities without erosion. A comparison of the reactions of AO and atomic chlorine with PE reveal a maximum incorporation of the corresponding C-O and C-Cl functionalities at the polymer surface. A novel method to prepare phosphorous-containing polymer surfaces through ion implantation of trimethyl phosphine onto PE is presented. Air exposure of the resulting P-implanted PE leads to the surface selective oxidation of phosphorous moieties. P-containing hydrocarbon films are used to model the surface chemical changes of P-containing polymers exposed to AO. Results indicate that oxidized phosphorous species protect the film from AO-induced erosion. The low temperature (<150 K) oxidation of nitrided iron surfaces exposed to oxygen reveal the formation of iron oxynitride (FexNyO z, nitrosonium ions (NO+) as well as nitrite/nitrito and nitrate type species. The production of nitrite/nitrito and nitrate species is taken as evidence for the existence of oxygen insertion chemistry into the iron nitride lattice under these low temperature oxidation conditions. Upon annealing the oxidized iron nitride surface, nitrogen desorbs exclusively as nitric oxide (NO).

Torres, Jessica

341

Model-based interpretation of stereo imagery of textured surfaces  

Microsoft Academic Search

.   We present a scheme for reliable and accurate surface reconstruction from stereoscopic images containing only fine texture\\u000a and no stable high-level features. Partial shape information is used to improve surface computation: first by fitting an approximate,\\u000a global, parametric model, and then by refining this model via local correspondence processes. This scheme eliminates the window\\u000a size selection problem in existing

Wen-yi Zhao; N. Nandhakumar; Philip W. Smith

1997-01-01

342

Surface Roughness Parameter Uncertainties on Radar Based Soil Moisture Retrievals  

NASA Technical Reports Server (NTRS)

Surface roughness variations are often assumed to be negligible for the retrieval of sol moisture. Although previous investigations have suggested that this assumption is reasonable for natural vegetation covers (i.e. Moran et al. 2002), in-situ measurements over plowed agricultural fields (i.e. Callens et al. 2006) have shown that the soil surface roughness can change considerably due to weathering induced by rain.

Joseph, A. T.; vanderVelde, R.; O'Neill, P. E.; Lang, R.; Su, Z.; Gish, T.

2012-01-01

343

Three-dimensional surface reconstruction based on laser triangulation  

Microsoft Academic Search

At the present time, a great number of applications exist that need the reconstruction of three-dimensional surfaces, such as: medicine, reverse engineer, industrial tasks and virtual world recreation. A system of reconstruction of surfaces was made up of three parts: capture of image, calibration of the camera and generation of a mesh from the cloud of three-dimensional points (3D). The

C. Lizcano; M. Marquez

2004-01-01

344

Topologically consistent trimmed surface approximations based on triangular patches  

Microsoft Academic Search

Topologically consistent algorithms for the intersection and trimming of free-form parametric surfaces are of fundamental importance in computer-aided design, analysis, and manufactur- ing. Since the intersection of (for example) two bicubic tensor-product surface patches is not a rational curve, it is usually described by approximations in the parameter domain of each sur- face. If these approximations are employed as \\

Rida T. Farouki; Chang Yong Han; Joel Hass; Thomas W. Sederberg

2004-01-01

345

Surface-recombination-free InGaAs/InP HBTs and the base contact recombination  

NASA Astrophysics Data System (ADS)

Surface-recombination-free InGaAs/InP HBTs with graded base have been demonstrated. The HBTs were passivated by ammonium sulfide. The current gain of the nonself-aligned HBTs was independent of the emitter periphery, indicating that the surface recombination was removed by the passivation. For the self-aligned HBTs, the current gain was still dependent on the emitter periphery after the passivation due to the base contact recombination. A surface leakage channel has been identified to result in a significant increase in the base contact recombination. The passivation has two effects: one is the surface recombination velocity reduction and the other is the surface leakage channel elimination.

Jin, Z.; Liu, X.; Prost, W.; Tegude, F.-J.

2008-07-01

346

Influence of surface properties of resin-based composites on in vitro Streptococcus mutans biofilm development.  

PubMed

The aim of this in vitro study was to evaluate the influence of physicochemical surface properties of resin-based composites on Streptococcus mutans biofilm formation. Specimens were prepared from each of four resin-based composites by polymerization against Mylar strips. Half of the number of specimens received no further surface treatment, whereas the other half were subjected to a polishing treatment. Surface roughness (SR) and topography were assessed using profilometry and atomic force microscopy. Surface free-energy (SFE) was determined, and the chemical surface composition was analysed by X-ray photoelectron spectroscopy (XPS). S. mutans biofilms were formed on the surface of the resin-based composite specimens for either 48 or 96 h using an artificial mouth system (AMS). Polishing caused a significant decrease in SFE, and XPS analysis indicated an increase of surface silicon and a decrease of surface carbon. Only for Grandio was a significant increase in SR identified after polishing, which was probably related to the higher concentration of filler particles on its surface. Significantly less S. mutans biofilm formation was observed on polished resin-based composites than on unpolished resin-based composites. These results indicate that the proportions of resin matrix and filler particles on the surface of resin-based composites strongly influence S. mutans biofilm formation in vitro, suggesting that minimization of resin matrix exposure might be useful to reduce biofilm formation on the surface of resin-based composites. PMID:22985005

Ionescu, Andrei; Wutscher, Elisabeth; Brambilla, Eugenio; Schneider-Feyrer, Sibylle; Giessibl, Franz J; Hahnel, Sebastian

2012-10-01

347

Acid base properties of cyanobacterial surfaces I: Influences of growth phase and nitrogen metabolism on cell surface reactivity  

NASA Astrophysics Data System (ADS)

Significant efforts have been made to elucidate the chemical properties of bacterial surfaces for the purposes of refining surface complexation models that can account for their metal sorptive behavior under diverse conditions. However, the influence of culturing conditions on surface chemical parameters that are modeled from the potentiometric titration of bacterial surfaces has received little regard. While culture age and metabolic pathway have been considered as factors potentially influencing cell surface reactivity, statistical treatments have been incomplete and variability has remained unconfirmed. In this study, we employ potentiometric titrations to evaluate variations in bacterial surface ligand distributions using live cells of the sheathless cyanobacterium Anabaena sp. strain PCC 7120, grown under a variety of batch culture conditions. We evaluate the ability for a single set of modeled parameters, describing acid-base surface properties averaged over all culture conditions tested, to accurately account for the ligand distributions modeled for each individual culture condition. In addition to considering growth phase, we assess the role of the various assimilatory nitrogen metabolisms available to this organism as potential determinants of surface reactivity. We observe statistically significant variability in site distribution between the majority of conditions assessed. By employing post hoc Tukey-Kramer analysis for all possible pair-wise condition comparisons, we conclude that the average parameters are inadequate for the accurate chemical description of this cyanobacterial surface. It was determined that for this Gram-negative bacterium in batch culture, ligand distributions were influenced to a greater extent by nitrogen assimilation pathway than by growth phase.

Lalonde, S. V.; Smith, D. S.; Owttrim, G. W.; Konhauser, K. O.

2008-03-01

348

Operational Satellite-based Surface Oil Analyses (Invited)  

NASA Astrophysics Data System (ADS)

During the Deepwater Horizon spill, NOAA imagery analysts in the Satellite Analysis Branch (SAB) issued more than 300 near-real-time satellite-based oil spill analyses. These analyses were used by the oil spill response community for planning, issuing surface oil trajectories and tasking assets (e.g., oil containment booms, skimmers, overflights). SAB analysts used both Synthetic Aperture Radar (SAR) and high resolution visible/near IR multispectral satellite imagery as well as a variety of ancillary datasets. Satellite imagery used included ENVISAT ASAR (ESA), TerraSAR-X (DLR), Cosmo-Skymed (ASI), ALOS (JAXA), Radarsat (MDA), ENVISAT MERIS (ESA), SPOT (SPOT Image Corp.), Aster (NASA), MODIS (NASA), and AVHRR (NOAA). Ancillary datasets included ocean current information, wind information, location of natural oil seeps and a variety of in situ oil observations. The analyses were available as jpegs, pdfs, shapefiles and through Google, KML files and also available on a variety of websites including Geoplatform and ERMA. From the very first analysis issued just 5 hours after the rig sank through the final analysis issued in August, the complete archive is still publicly available on the NOAA/NESDIS website http://www.ssd.noaa.gov/PS/MPS/deepwater.html SAB personnel also served as the Deepwater Horizon International Disaster Charter Project Manager (at the official request of the USGS). The Project Manager’s primary responsibility was to acquire and oversee the processing and dissemination of satellite data generously donated by numerous private companies and nations in support of the oil spill response including some of the imagery described above. SAB has begun to address a number of goals that will improve our routine oil spill response as well as help assure that we are ready for the next spill of national significance. We hope to (1) secure a steady, abundant and timely stream of suitable satellite imagery even in the absence of large-scale emergencies such as Deepwater Horizon, (2) acquire a 24 x 7 oil spill response capability at least on a pre-operational basis, (3) acquire improved and expanded ancillary datasets, (4) reduce the number of false positives (analyzed oil that is not actually oil), (5) acquire the ability to reliably differentiate, at least in general qualitative terms, thick oil (“recoverable oil”) from oil sheens, and (6) join our Canadian counterparts (the Integrated Satellite Tracking of Pollution group in Environment Canada) to create a joint North American center for oil spill response.

Streett, D.; Warren, C.

2010-12-01

349

Facile creation of bio-inspired superhydrophobic Ce-based metallic glass surfaces  

NASA Astrophysics Data System (ADS)

A bio-inspired synthesis strategy was conducted to fabricate superhydrophobic Ce-based bulk metallic glass (BMG) surfaces with self-cleaning properties. Micro-nanoscale hierarchical structures were first constructed on BMG surfaces and then modified with the low surface energy coating. Surface structures, surface chemical compositions, and wettability were characterized by combining scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and contact angle measurements. Research indicated that both surface multiscale structures and the low surface free energy coating result in the final formation of superhydrophobicity.

Liu, Kesong; Li, Zhou; Wang, Weihua; Jiang, Lei

2011-12-01

350

An assessment of conventional and self-ligating brackets in Class I maxillary constriction patients.  

PubMed

ABSTRACT Objective: To evaluate two different treatment systems with regard to incisor position, transverse dimension changes in maxillary arch, changes in maxillary molar inclinations, clinical periodontal parameters, and pain intensity in patients with a Class I malocclusion. Materials and Methods: Seventeen patients (with a mean age of 14.5 years) underwent orthodontic treatment with the Roth prescribed edgewise bracket systems after expanding the maxillary arch with a quad-helix appliance, and 16 patients (with a mean age of 14.8 years) underwent orthodontic treatment with the Damon 3MX bracket system. Each subject's lateral cephalometric and posteroanterior radiographs and dental casts were obtained at the beginning of the treatment and after debonding. In addition to these, the periodontal index and pain scores were taken. Results: Cephalometric data showed that in both treatment systems, overjet value decreased and maxillary and mandibular incisors proclined. Posteroanterior measurements demonstrated a greater increase in the maxillary molar inclination in the Damon group. Significant increase of maxillary intercanine, interpremolar, and intermolar widths was shown in both systems. Periodontal index and pain score changes between different observation periods were the same. Conclusions: The conventional and Damon systems were found similar with regard to the incisor position, transverse dimension changes in maxillary arch, clinical periodontal parameters, and pain intensity. The only significant difference was that the Damon system inclined the maxillary molars more buccally than the conventional group. PMID:24423203

Atik, Ezgi; Ci?er, Semra

2014-07-01

351

Shear bond strength of a new dental adhesive used to bond brackets to unetched enamel.  

PubMed

The aims of the present study were to measure the shear bond strength of a new multipurpose dental adhesive, IntegraCem, for direct bonding of stainless steel and ceramic brackets to unetched enamel, and to determine the mode of bond failure. Both stainless steel and ceramic brackets (GAC) were bonded with IntegraCem to unetched extracted human premolars. After bonding, the teeth were either stored in a water bath at 37 degrees C for 3 days or passed 2500 thermocycles from 6 to 60 degrees C. Debonding was then performed with a shearing force using an Instron universal testing machine. The force was recorded at bond failure. The results showed that the shear bond strength achieved was between 6.7 and 10.8 megapascals (MPa). Bond failure occurred at the enamel-adhesive interface, enabling more efficient enamel clean up. The shear bond strengths measured suggest that IntegraCem adhesive may be effectively used in orthodontic treatment. PMID:12407947

Harari, Doron; Gillis, Immanuel; Redlich, Meir

2002-10-01

352

Surface Danger Zone (SDZ) Methodology Study, Probability Based Surface Danger Zones.  

National Technical Information Service (NTIS)

Surface danger zones (SDZs) are exclusion areas identified to protect personnel from weapons firing during training. Limited real estate at certain training sites and observation of inadequacies in current danger zones has forced the Army to investigate a...

E. B. Vazquez S. Hoxha

1995-01-01

353

Surface acid-base characteristics of fiber materials by contact angle measurements  

SciTech Connect

Contact angle measurements were used to study the surface acid-base characteristics of treated and untreated carbon fibers, and of treated and untreated silicon carbide fibers. It has been shown that, when untreated the surfaces of these two fibers exhibits amphoteric, but the base character is dominant. After oxidization in a liquid phase, the surface acid character of the carbon fibers changes little, whereas the base character becomes much stronger. The treatment, with boiling-concentrated HNO[sub 3] for three hours and the sintering treatment in air at 500 C. for eight hours, has little effect on the surface acid-base characteristics of the silicon carbide fibers.

Mao Youan (National Univ., of Defense and Technology, Changsha (China). Dept. of Materials Science and Applied Chemistry)

1993-11-05

354

MR-Less Surface-Based Amyloid Assessment Based on 11C PiB PET  

PubMed Central

Background ?-amyloid (A?) plaques in brain's grey matter (GM) are one of the pathological hallmarks of Alzheimer's disease (AD), and can be imaged in vivo using Positron Emission Tomography (PET) with 11C or 18F radiotracers. Estimating A? burden in cortical GM has been shown to improve diagnosis and monitoring of AD. However, lacking structural information in PET images requires such assessments to be performed with anatomical MRI scans, which may not be available at different clinical settings or being contraindicated for particular reasons. This study aimed to develop an MR-less A? imaging quantification method that requires only PET images for reliable A? burden estimations. Materials and Methods The proposed method has been developed using a multi-atlas based approach on 11C-PiB scans from 143 subjects (75 PiB+ and 68 PiB- subjects) in AIBL study. A subset of 20 subjects (PET and MRI) were used as atlases: 1) MRI images were co-registered with tissue segmentation; 2) 3D surface at the GM-WM interfacing was extracted and registered to a canonical space; 3) Mean PiB retention within GM was estimated and mapped to the surface. For other participants, each atlas PET image (and surface) was registered to the subject's PET image for PiB estimation within GM. The results are combined by subject-specific atlas selection and Bayesian fusion to generate estimated surface values. Results All PiB+ subjects (N?=?75) were highly correlated between the MR-dependent and the PET-only methods with Intraclass Correlation (ICC) of 0.94, and an average relative difference error of 13% (or 0.23 SUVR) per surface vertex. All PiB- subjects (N?=?68) revealed visually akin patterns with a relative difference error of 16% (or 0.19 SUVR) per surface vertex. Conclusion The demonstrated accuracy suggests that the proposed method could be an effective clinical inspection tool for A? imaging scans when MRI images are unavailable.

Zhou, Luping; Salvado, Olivier; Dore, Vincent; Bourgeat, Pierrick; Raniga, Parnesh; Macaulay, S. Lance; Ames, David; Masters, Colin L.; Ellis, Kathryn A.; Villemagne, Victor L.; Rowe, Christopher C.; Fripp, Jurgen

2014-01-01

355

Magnesium-based composites with improved in vitro surface biocompatibility  

PubMed Central

In this study, bioactive glass (BG, 45S5) particles were added to a biodegradable magnesium alloy (ZK30) through a semi-solid high-pressure casting process in order to improve the surface biocompatibility of the biomaterial and potentially its bioactivity. The observation of the as-cast microstructures of ZK30-BG composites indicated homogeneous dispersion of BG particles in the matrix. SEM, EDX and EPMA showed the retention of the morphological characteristics and composition of BG particles in the as-cast composite materials. In vitro tests in a cell culture medium confirmed that the composites indeed possessed an enhanced ability to induce the deposition of a bone-like apatite layer on the surface, indicating an improved surface biocompatibility as compared with the matrix alloy.

Huan, Zhiguang; Duszczyk, Jurek

2010-01-01

356

Cyclodextrin-based surface acoustic wave chemical microsensors  

SciTech Connect

Cyclodextrin thin films were fabricated using either self-assembled monolayer (SAM) or solgel techniques. The resulting host receptor thin films on the substrates of surface acoustic wave (SAW) resonators were studied as method of tracking organic toxins in vapor phase. The mass loading of surface-attached host monolayers on SAW resonators gave frequency shifts corresponding to typical monolayer surface coverages for SAM methods and ``multilayer`` coverages for sol-gel techniques. Subsequent exposure of the coated SAW resonators to organic vapors at various concentrations, typically 5,000 parts per millions (ppm) down to 100 parts per billions (ppb) by mole, gave responses indicating middle-ppb-sensitivity ({approximately}50 ppb) for those sensor-host-receptors and organic-toxin pairs with optimum mutual matching of polarity, size, and structural properties.

Li, D.Q.; Shi, J.X.; Springer, K.; Swanson, B.I.

1996-07-01

357

Characterization and Applications of Affinity Based Surface Modification of Polypyrrole  

NASA Astrophysics Data System (ADS)

I present the characterization and applications of a technique to modify the surface of the conducting polymer, polypyrrole, via a novel, 12-amino acid peptide, THRTSTLDYFVI (T59). This peptide non-covalently binds to the chlorine-doped conducting polymer polypyrrole, allowing it to be used in tethering molecules to polypyrrole for uses such as a scaffold for the treatment of peripheral nerve injury or in surface coatings of neural recording electrodes. I have quantified the binding of this peptide as well as investigating the mechanism of the binding. The equilibrium constant of the binding interaction of PPyCl and the T59 peptide was found through a binding assay to be 92.6 nM, and the off rate was found to be approximately 2.49 s-1, via AFM force spectroscopy. The maximum observed surface density of the peptide was 1.27 +/- 0.42 femtomoles/cm2. Furthermore, my studies suggest that the eighth residue, aspartic acid, is the main contributor of the binding, by interacting with the partially positive charge on the backbone of polypyrrole. I have demonstrated practical applications of the technique in the successful modification of a PPyCl surface with the laminin fragment IKVAV, as well as the so-called stealth molecule poly(ethylene glycol) (PEG). A subcutaneous implant study was performed to confirm that the T59 peptide did not induce any significant reaction in vivo. Significantly, the conductivity of a PPyCl surface was unaffected by this surface modification technique.

Nickels, Jonathan D.

358

Investigation of possibility of surface rupture derived from PFDHA and calculation of surface displacement based on dislocation  

NASA Astrophysics Data System (ADS)

A probability of surface rupture is important to configure the seismic source, such as area sources or fault models, for a seismic hazard evaluation. In Japan, Takemura (1998) estimated the probability based on the historical earthquake data. Kagawa et al. (2004) evaluated the probability based on a numerical simulation of surface displacements. The estimated probability indicates a sigmoid curve and increases between Mj (the local magnitude defined and calculated by Japan Meteorological Agency) =6.5 and Mj=7.0. The probability of surface rupture is also used in a probabilistic fault displacement analysis (PFDHA). The probability is determined from the collected earthquake catalog, which were classified into two categories: with surface rupture or without surface rupture. The logistic regression is performed for the classified earthquake data. Youngs et al. (2003), Ross and Moss (2011) and Petersen et al. (2011) indicate the logistic curves of the probability of surface rupture by normal, reverse and strike-slip faults, respectively. Takao et al. (2013) shows the logistic curve derived from only Japanese earthquake data. The Japanese probability curve shows the sharply increasing in narrow magnitude range by comparison with other curves. In this study, we estimated the probability of surface rupture applying the logistic analysis to the surface displacement derived from a surface displacement calculation. A source fault was defined in according to the procedure of Kagawa et al. (2004), which determined a seismic moment from a magnitude and estimated the area size of the asperity and the amount of slip. Strike slip and reverse faults were considered as source faults. We applied Wang et al. (2003) for calculations. The surface displacements with defined source faults were calculated by varying the depth of the fault. A threshold value as 5cm of surface displacement was used to evaluate whether a surface rupture reach or do not reach to the surface. We carried out the logistic regression analysis to the calculated displacements, which were classified by the above threshold. The estimated probability curve indicated the similar trend to the result of Takao et al. (2013). The probability of revere faults is larger than that of strike slip faults. On the other hand, PFDHA results show different trends. The probability of reverse faults at higher magnitude is lower than that of strike slip and normal faults. Ross and Moss (2011) suggested that the sediment and/or rock over the fault compress and not reach the displacement to the surface enough. The numerical theory applied in this study cannot deal with a complex initial situation such as topography.

Inoue, N.; Kitada, N.; Irikura, K.

2013-12-01

359

The comparison of frictional resistance in titanium, self-ligating stainless steel, and stainless steel brackets using stainless steel and TMA archwires: An in vitro study  

PubMed Central

Aim: The aim of the study was to compare the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and titanium molybdenum alloy (TMA) archwires. Materials and Methods: We compared the frictional resistance in 0.018 slot and 0.022 slot of the three brackets – titanium, self-ligating stainless steel, and conventional stainless steel – using stainless steel archwires and TMA archwires. An in vitro study of simulated canine retraction was undertaken to evaluate the difference in frictional resistance between titanium, self-ligating stainless steel, and stainless steel brackets, using stainless steel and TMA archwires. Results and Conclusion: We compared the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and TMA archwires, with the help of Instron Universal Testing Machine. One-way analysis of variance (ANOVA), Student's “t” test, and post hoc multiple range test at level of <0.05 showed statistically significant difference in the mean values of all groups. Results demonstrated that the titanium, self-ligating stainless steel, and stainless steel brackets of 0.018-inch and 0.022-inch slot had no significant variations in frictional résistance. The self-ligating bracket with TMA archwires showed relatively less frictional resistance compared with the other groups. The titanium bracket with TMA archwires showed relatively less frictional resistance compared with the stainless steel brackets.

Khalid, Syed Altaf; Kumar, Vadivel; Jayaram, Prithviraj

2012-01-01

360

Radar Absorbers Based on Frequency Selective Surfaces on Perforated Substrates  

Microsoft Academic Search

A new type of metamaterials is introduced which can be fabricated by printing metal patches on inhomogeneous, periodic substrates. Such structures without periodic substrate are known as Frequency Selective Surfaces (FSS) but they are more promising for EMC shielding than common FSS structures because both the effective dielectric permittivity and loss of the substrate can be controlled. A numerical method

Arya Fallahi; Matthew Mishrikey; Christian Hafner; Rüdiger Vahldieck

361

A Taxonomy of Global Optimization Methods Based on Response Surfaces  

Microsoft Academic Search

This paper presents a taxonomy of existing approaches for using response surfaces for global optimization. Each method is illustrated with a simple numerical example that brings out its advantages and disadvantages. The central theme is that methods that seem quite reasonable often have non-obvious failure modes. Understanding these failure modes is essential for the development of practical algorithms that fulfill

DONALD R. JONES

2001-01-01

362

A response surface methodology based damage identification technique  

Microsoft Academic Search

Response surface methodology (RSM) is a combination of statistical and mathematical techniques to represent the relationship between the inputs and outputs of a physical system by explicit functions. This methodology has been widely employed in many applications such as design optimization, response prediction and model validation. But so far the literature related to its application in structural damage identification (SDI)

S. E. Fang; R. Perera

2009-01-01

363

Triangulation-Based L1-Fitting of Terrain Surfaces.  

National Technical Information Service (NTIS)

Given a planar triangulation, the goal is to select elevations at its vertices so that resulting piecewise-linear triangulated surface approximates specified elevations using the L(sub 1)-norm as the primary measure-of-fit. Several suboptimal algorithms r...

J. Bernal C. Witzgall

1999-01-01

364

Tilted refractive surfaces at Eglin Air Force Base, Florida  

NASA Astrophysics Data System (ADS)

Radar ducting layers along the Gulf coast of Florida are examined for a 9-day period in May of 1976. Tilted refractive surfaces are shown to exist with enough of a slope to significantly increase the chance of radar ducting at small look angles. Radiosonde observations are found to agree with average refractometer measurements but do not detect ducting layers with small vertical depths.

Schleher, J. S.

1982-10-01

365

Video based surface alignment technique for 3D patient positioning  

Microsoft Academic Search

Presents a technique to align a 3D surface model of a patient to video images of the patient on the treatment table. The technique can be used to quantify patient positioning errors in 3D. Three video cameras were mounted to the ceiling of the treatment room and geometrically calibrated in linear accelerator beam coordinate system. The calibration essentially determines how

S. W. Hadley; L. S. Johnson; C. A. Pelizzari

2000-01-01

366

Asteroid surface mineralogy: Evidence from earth-based telescope observations  

NASA Technical Reports Server (NTRS)

The interpretation of asteroid reflectance spectrophotometry in terms of mineralogical types gives inferred mineral assemblages for about 60 asteroids. Asteroid surface materials are compared with similar materials that make up many meteorites. The absence of asteroids with spectra that match identically the ordinary chondrites is noted.

Mccord, T. B.

1978-01-01

367

Micro mixer based on surface acoustic wave driving  

NASA Astrophysics Data System (ADS)

A resonance frequency of 8.9MHz copper Interdigital Transducer (IDT) is fabricated on a 127.8°YX type LiNbO3 substrate by lift-off process and the rapid droplet mixing is experimentally realized using the surface acoustic wave(SAW). The droplet mixing principle and the manufacturing process of the mixer are illustrated in detail. The droplet generates one swirl when only portion of the droplet is located on the saw propagating surface. The droplet generates two swirls when the whole of droplet is located on the saw propagating surface. The mixing between red particles with an average diameter of 1.5?m and a droplet with a volume of 3 ?l is successfully implemented. No matter the droplet covers whole or just partly the saw propagating surface, the mixing process can be completed in one second when the applied driving power is 9W. The applications of SAW micro fluidics should be greatly enhanced using the rapid mixing process proposed in this paper.

Zhang, Guan; Li, Yigui; Zhang, Junfeng; Yang, Chunshen; Liu, Jingquan

2010-08-01

368

HandsDown: hand-contour-based user identification for interactive surfaces  

Microsoft Academic Search

HandsDown is a novel technique for user identification on interactive surfaces. It enables users to access personal data on a shared surface, to associate objects with their identity, and to fluidly customize appearance, content, or functionality of the user interface. To identify, users put down their hand flat on the surface. HandsDown is based on hand contour analysis; neither user

Dominik Schmidt; Ming Ki Chong; Hans Gellersen

2010-01-01

369

A Novel Surface Tension Coefficient Measurement Method Based on Microposts Array Microfluidic Chip  

Microsoft Academic Search

A novel surface tension measurement method based on microposts array microfluidic chip is presented and the fabrication process is studied. When the surface tension balance was broken due to evaporation, the tips of the microposts array submerged in aqueous solvent were pulled as vertical micro-cantilever at the liquid-air interface and displaced. In micro- or nanometers scale, the surface area to

Zhiguo Zhou; Zhiwen Liu

2011-01-01

370

The Effect of Base Paper and Coating Method on the Surface Roughness of Pigment Coatings  

Microsoft Academic Search

Ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) was applied on base paper with various coating amounts and two different coating methods. The surface topographical images were captured by atomic force microscopy and confocal optical microscopy. The surface roughness of pigment coatings was analyzed by using a two-point correlation method where both the amplitude and lateral spacing of surface

S. Wang; P. Ihalainen; J. Järnström; J. Peltonen

2009-01-01

371

Theoretical analysis of cell separation based on cell surface marker density  

Microsoft Academic Search

A theoretical analysis was performed to deter- mine the number of fractions a multidisperse, immuno- magnetically labeled cell population can be separated into based on the surface marker (antigen) density. A number of assumptions were made in this analysis: that there is a proportionality between the number of surface markers on the cell surface and the number of immuno- magnetic

Jeffrey J. Chalmers; Maciej Zborowski; Lee Moore; Sushim Mandal; BingBing Fang; Liping Sun

1998-01-01

372

Surfaces in RN2-1 based on harmonic maps S2-->CPN-1  

NASA Astrophysics Data System (ADS)

We show that many surfaces in RN2-1 can be generated by harmonic maps of S2-->CPN-1. These surfaces are based on the projectors in CPN-1 which describe maps of S2-->CPN-1. In the case when these maps form the Veronese sequence, all the surfaces have a constant curvature.

Zakrzewski, W. J.

2007-11-01

373

An Electrolysis-Bubble-Actuated Micropump Based on the Roughness Gradient Design of Hydrophobic Surface  

Microsoft Academic Search

A novel electrolysis-bubble-actuated micropump based on the roughness gradient design in the microchannel is reported in this paper. This micropump is implemented by taking advantage of both the electrolysis actuation and the surface tension effect. The surface tension effect is controlled via the periodic generation of electrolytic bubbles and the roughness gradient design of microchannel surface, which results in the

Chih-Ming Cheng; Cheng-Hsien Liu

2007-01-01

374

Surface extraction for volume rendering based on zero crossing points detection in wavelet domain  

Microsoft Academic Search

Surface extraction is a popular preprocessing method for volume rendering acceleration. We discuss a surface extraction algorithm based on the wavelet transform. Given a basis wavelet function meeting certain conditions, the points on object surfaces can be picked up by detection of zero crossing points from the 3D wavelet transform components of the volume data. The experimental results show that

Shen Haige; Wang Weidong; Ke Youan

2000-01-01

375

Effects of deformation behavior on fatigue fracture surface morphology in a nickel-base superalloy  

Microsoft Academic Search

Fatigue crack propagation fracture surface morphologies in nickel-base superalloys vary substantially with changes in loading parameters such as temperature, ?K, load ratio, frequency, and additionally microstructure. Quantitative fracture surface roughness can vary from sub-micron levels to a maximum value of approximately half the grain size. Atomic Force Microscope studies of surface slip traces in compression specimens revealed a clear relationship

A Shyam; W. W Milligan

2004-01-01

376

Surface modification of polyacrylonitrile-based carbon fiber and its interaction with imide  

Microsoft Academic Search

In this work, sized polyacrylonitrile (PAN)-based carbon fibers were chemically modified with nitric acid and maleic anhydride (MA) in order to improve the interaction between carbon fiber surface and polyimide matrix. Bismaleimide (BMI) was selected as a model compound of polyimide to react with modified carbon fiber. The surface characteristic changing after modification and surface reaction was investigated by element

Bing Xu; Xiaoshu Wang; Yun Lu

2006-01-01

377

Listener-based analysis of surface importance for acoustic metrics.  

PubMed

Acoustic quality in room acoustics is measured by well defined quantities, like definition, which can be derived from simulated impulse response filters or measured values. These take into account the intensity and phase shift of multiple reflections due to a wave front emanating from a sound source. Definition (D50) and clarity (C50) for example correspond to the fraction of the energy received in total to the energy received in the first 50 ms at a certain listener position. Unfortunately, the impulse response measured at a single point does not provide any information about the direction of reflections, and about the reflection surfaces which contribute to this measure. For the visualization of room acoustics, however, this information is very useful since it allows to discover regions with high contribution and provides insight into the influence of all reflecting surfaces to the quality measure. We use the phonon tracing method to calculate the contribution of the reflection surfaces to the impulse response for different listener positions. This data is used to compute importance values for the geometry taking a certain acoustic metric into account. To get a visual insight into the directional aspect, we map the importance to the reflecting surfaces of the geometry. This visualization indicates which parts of the surfaces need to be changed to enhance the chosen acoustic quality measure. We apply our method to the acoustic improvement of a lecture hall by means of enhancing the overall speech comprehensibility (clarity) and evaluate the results using glyphs to visualize the clarity (C50) values at listener positions throughout the room. PMID:17968125

Michel, Frank; Deines, Eduard; Hering-Bertram, Martin; Garth, Christoph; Hagen, Hans

2007-01-01

378

Understanding the Water Retention of Composite Proton Exchange Membranes Based on Surface Chemistry of Inorganic Fillers  

SciTech Connect

Use of metal oxide additives is considered a viable option for improving thermal, chemical, and transport properties of the proton exchange membranes for fuel cells operating at elevated temperatures (>100 C) and reduced relative humidity (<70%). The purpose of this paper is to review the characteristics of some specific oxide materials for fuel cell applications based on available experimental surface chemistry data and surface modeling. Several commonly used oxides were differentiated based on their thermodynamic solubility, surface charge, and states of the surface water. Surface charge is discussed as a primary factor controlling water retention by the composite membranes in dehydrating environments.

Fedkin, Mark V. [Pennsylvania State University; Chalkova, E. [Pennsylvania State University; Wesolowski, David J [ORNL; Lvov, Serguei N. [Pennsylvania State University

2008-01-01

379

Surface parameterization in volumetric images for curvature-based feature classification.  

PubMed

Curvature-based surface features are well suited for use in multimodal medical image registration. The accuracy of such feature-based registration techniques is dependent upon the reliability of the feature computation. The computation of curvature features requires second derivative information that is best obtained from a parametric surface representation. We present a method of explicitly parameterizing surfaces from volumetric data. Surfaces are extracted, without a global thresholding, using active contour models. A monge/spl acute/ basis for each surface patch is estimated and used to transform the patch into local, or parametric, coordinates. Surface patches are fit to a bicubic polynomial in local coordinates using least squares solved by singular value decomposition. We tested our method by reconstructing surfaces from the surface model and analytically computing Gaussian and mean curvatures. The model was tested on analytical and medical data. PMID:18238229

Quek, F H; Yarger, R I; Kirbas, C

2003-01-01

380

Nanosensors based on functionalized nanoparticles and surface enhanced raman scattering  

DOEpatents

Surface-Enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopic technique that utilizes metal surfaces to provide enhanced signals of several orders of magnitude. When molecules of interest are attached to designed metal nanoparticles, a SERS signal is attainable with single molecule detection limits. This provides an ultrasensitive means of detecting the presence of molecules. By using selective chemistries, metal nanoparticles can be functionalized to provide a unique signal upon analyte binding. Moreover, by using measurement techniques, such as, ratiometric received SERS spectra, such metal nanoparticles can be used to monitor dynamic processes in addition to static binding events. Accordingly, such nanoparticles can be used as nanosensors for a wide range of chemicals in fluid, gaseous and solid form, environmental sensors for pH, ion concentration, temperature, etc., and biological sensors for proteins, DNA, RNA, etc.

Talley, Chad E. (Brentwood, CA); Huser, Thomas R. (Livermore, CA); Hollars, Christopher W. (Brentwood, CA); Lane, Stephen M. (Oakland, CA); Satcher, Jr., Joe H. (Patterson, CA); Hart, Bradley R. (Brentwood, CA); Laurence, Ted A. (Livermore, CA)

2007-11-27

381

Surface plasmon-based infrared spectroscopy for cell biosensing  

NASA Astrophysics Data System (ADS)

Cell morphology is often used as a valuable indicator of the physical condition and general status of living cells. We demonstrate a noninvasive method for morphological characterization of adherent cells. We measure infrared reflectivity spectrum at oblique angle from living cells cultured on thin Au film, and utilize the unique properties of the confined infrared waves (i.e., surface plasmon and guided modes) traveling inside the cell layer. The propagation of these waves strongly depends on cell morphology and connectivity. By tracking the resonant wavelength and attenuation of the surface plasmon and guided modes we measure the kinetics of various cellular processes such as (i) cell attachment and spreading on different substrata, (ii) modulation of the outer cell membrane with chlorpromazine, and (iii) formation of intercellular junctions associated with progressive cell polarization. Our method enables monitoring of submicron variations in cell layer morphology in real-time, and in the label-free manner.

Yashunsky, Victor; Lirtsman, Vladislav; Zilbershtein, Alexander; Bein, Amir; Schwartz, Betty; Aroeti, Benjamin; Golosovsky, Michael; Davidov, Dan

2012-08-01

382

Environmentally friendly plasma-based surface engineering technologies  

NASA Astrophysics Data System (ADS)

Weakly ionised reactive plasmas are characterised by a very low degree of ionization, which rarely exceeds the order of 10-4, and by a very high degree of dissociation, which often reaches values above 50%. Thus the most numerous plasma species are free neutral atoms originated from the dissociation of the source gas molecules. Neutral atoms are chemically very reactive species, which makes such plasma suitable for material processing. At the same time the neutral atoms have a low kinetic energy and therefore they cannot penetrate into the bulk material, so their effect is restricted to the topmost atomic layers of the material surface hence weakly ionised, reactive plasmas are suitable for surface engineering. Here we present examples of weakly ionised plasma applications as environmentally friendly alternatives to processes that otherwise utilise aggressive chemicals and produce toxic waste.

Drenik, A.; Mozetic, M.; Vesel, A.; Cvelbar, U.

2010-01-01

383

Aptamer-based surface plasmon fibre sensor for thrombin detection  

NASA Astrophysics Data System (ADS)

A series of surface plasmonic fibre devices were fabricated using multiple coatings deposited on a lapped section of a single mode fibre and post-fabrication UV laser irradiation processing with a phase mask, producing a surface relief grating structure. These devices showed high spectral sensitivity in the aqueous index regime ranging up to 4000 nm/RIU for wavelength and 800 dB/RIU for intensity. The devices were then coated with human thrombin binding aptamer. Several concentrations of thrombin in buffer solution were made, ranging from 1nM to 1?M. All the concentrations were detectable by the devices demonstrating that sub-nM concentrations may be monitored.

Allsop, T.; Nagel, D.; Neal, R.; Davies, E. M.; Mou, C.; Bond, P.; Rehman, S.; Kalli, K.; Webb, D. J.; Calverhouse, P.; Mascini, M.; Bennion, I.

2010-04-01

384

Surface Plasmon Resonance for Cell-Based Clinical Diagnosis  

PubMed Central

Non-invasive real-time observations and the evaluation of living cell conditions and functions are increasingly demanded in life sciences. Surface plasmon resonance (SPR) sensors detect the refractive index (RI) changes on the surface of sensor chips in label-free and on a real-time basis. Using SPR sensors, we and other groups have developed techniques to evaluate living cells' reactions in response to stimuli without any labeling in a real-time manner. The SPR imaging (SPRI) system for living cells may visualize single cell reactions and has the potential to expand application of SPR cell sensing for clinical diagnosis, such as multi-array cell diagnostic systems and detection of malignant cells among normal cells in combination with rapid cell isolation techniques.

Yanase, Yuhki; Hiragun, Takaaki; Ishii, Kaori; Kawaguchi, Tomoko; Yanase, Tetsuji; Kawai, Mikio; Sakamoto, Kenji; Hide, Michihiro

2014-01-01

385

Nanomaterial sensing layer based surface acoustic wave hydrogen sensors  

Microsoft Academic Search

Pd-cluster coated, engineered tobacco mosaic virus (TMV) and similarly coated single-walled carbon nanotube (SWNT) particles have been studied for hydrogen detection with the help of surface acoustic wave (SAW) resonators. SAW resonators were coated with these two different nano-structured sensing layers (Pd-TMV and Pd-SWNT) which produced differently useful hydrogen sensor responses. The Pd-TMV coated resonator responded to hydrogen with nearly

krishnan Srinivasan; Stefan Cular; V. R. Bhethanabotla; Sang Yup Lee; Michael T. Harris

2005-01-01

386

Video-based online face recognition using identity surfaces  

Microsoft Academic Search

A multi-view dynamic face model is designed to extract the shape-and-pose-free texture patterns effaces. The model provides a precise correspondence to the task of recognition since the 3D shape information is used to warp the multi-view faces onto the model mean shape in frontal-view. The identity surface of each subject is constructed in a discriminant feature space from a sparse

Yongmin Li; Shaogang Gong; Heather Liddell

2001-01-01

387

Biodegradation-based polymer surface erosion and surface renewal for foul-release at low ship speeds.  

PubMed

Non-toxic foul-release provides an environmentally friendly and sustainable technical solution to control micro- and/or macrofouling on ships' hulls. Silicone-based coatings have been used for foul-release at high or moderate ship speeds (> 15 knots). To remove the fouling from slower ships (< 15 knots), the macrofoulers in particular, biodegradable polymers may be used to make the coating surface self-renewable. Synthesized by micro-organisms for carbon and energy storage under controlled conditions, polyhydroxyalkanoates (PHAs) are hydrophobic bipolymers that are gradually decomposed into CO2 and water in the environment. Because of their hydrophobic property and lack of hydrolysis in sterile aqueous solution, PHAs do not dissolve in water, but erode at the polymer surface (2-5 microns in depth) catalyzed exclusively by microbial enzymes (depolymerases) that are attached on the solid surface. The thin-layer surface erosion behaves like a self-renewable surface coating, which approaches a constant renewal rate at a relative hydraulic speed as low as 3 knots. A turbulence eddy model is used to describe the effect of energy consumption per mass of liquid on the turbulent shear stress and the surface renewal rate. Furthermore, the polymer biodegradation or surface renewal rate can be controlled within a broad range by blending the material with polymers such as poly (epsilon-caprolactone) (PCL). The biodegradation of binary blends of PHA/PCL of different compositions was quantitatively monitored by means of weight loss and Raman spectroscopy. PMID:14618708

Yu, Jian

2003-04-01

388

Surface Plasmon Resonance Based Sensitive Immunosensor for Benzaldehyde Detection  

NASA Astrophysics Data System (ADS)

Fragrant compounds used to add flavor to beverages remain in the manufacturing line after the beverage manufacturing process. Line cleanliness before the next manufacturing cycle is difficult to estimate by sensory analysis, making excessive washing necessary. A new measurement system to determine line cleanliness is desired. In this study, we attempted to detect benzaldehyde (Bz) using an anti-Bz monoclonal antibody (Bz-Ab) and a surface plasmon resonance (SPR) sensor. We fabricated two types of sensor chips using self-assembled monolayers (SAMs) and investigated which sensor surface exhibited higher sensitivity. In addition, anti-Bz antibody conjugated with horseradish peroxidase (HRP-Bz-Ab) was used to enhance the SPR signal. A detection limit of ca. 9ng/mL (ppb) was achieved using an immobilized 4-carboxybenzaldehyde sensor surface using SAMs containing ethylene glycol. When the HRP-Bz-Ab concentration was reduced to 30ng/mL, a detection limit of ca. 4ng/mL (ppb) was achieved for Bz.

Onodera, Takeshi; Shimizu, Takuzo; Miura, Norio; Matsumoto, Kiyoshi; Toko, Kiyoshi

389

Ultrasmooth surface polishing based on the hydrodynamic effect.  

PubMed

This study will examine the feasibility of applying the hydrodynamic effect to ultrasmooth surface polishing. Differing from conventional pad polishing, hydrodynamic effect polishing is noncontact, as the polishing wheel is floated on the workpiece under the hydrodynamic effect. The material removal mechanism and the removal contour are analyzed in detail. Dynamic pressure and shear stress distribution on the workpiece are numerically simulated in three dimensions under different clearances between the polishing wheel and the workpiece, showing that the dynamic pressure distribution and the magnitude of shear stress on the workpiece are greatly influenced by the clearance. It is clearly demonstrated from fixed-point polishing experiments that material removal rates and contours are determined by the combined action of dynamic pressure and shear stress. A material removal analytic model is presented with the hydrodynamic effect polishing method. Finally, a polishing experiment is conducted on a quartz glass and the plastic scratches, cracks, and bumpy structures on the initial surface are clearly removed. Moreover, the processed surface roughness is improved to 0.145 nm rms, 0.116 nm Ra. PMID:24085104

Peng, Wenqiang; Guan, Chaoliang; Li, Shengyi

2013-09-01

390

Reliability-based topology optimization using successive standard response surface method  

Microsoft Academic Search

Standard response surface method (SRSM) is used for generating limit state function since the chosen random variables are independent each other. Also, successive SRSM is implemented for obtaining an accurate limit state function with much fewer experimental points than traditional response surface method (RSM). Reliability-based topology optimization (RBTO) based on bi-directional evolutionary structural optimization (BESO) using RSM and successive SRSM

Kwang-Sun Yoo; Young-Sop Eom; Jae-Yong Park; Min-Gyu Im; Seog-Young Han

2011-01-01

391

Calibration and Validation of Earth-Observing Sensors Using Deployable Surface-Based Sensor Networks  

Microsoft Academic Search

Satellite-based instruments are now routinely used to map the surface of the globe or monitor weather conditions. However, these orbital measurements of ground-based quantities are heavily influenced by external factors, such as air moisture content or surface emissivity. Detailed atmospheric models are created to compensate for these factors, but the satellite system must still be tested over a wide variety

Stephen Williams; Lonnie T. Parker; Ayanna M. Howard

2010-01-01

392

A complete analytic surface potential-based core model for intrinsic nanowire surrounding-gate MOSFETs  

Microsoft Academic Search

An analytic surface potential-based non-charge-sheet core model for intrinsic nanowire surrounding-gate (SRG) MOSFETs is presented in this paper. Starting from the Poisson–Boltzmann equation in the cylindrical SRG MOSFETs, a surface potential equation is derived. Based on the exact surface potential solutions evaluated at the source and drain ends, a single set of the analytic drain current expression is obtained from

Jin He; Lining Zhang; Jian Zhang; Chenyue Ma; Feilong Liu; Mansun Chan

2009-01-01

393

Poster: Design considerations for fabric-based input for surface design  

Microsoft Academic Search

Fabric is a dynamic, flexible surface material that holds promise to represent many different kinds of surfaces. We explore how we can use such a flexible material as an interactive 3D input device for various kinds of surface design, such as garment and 3D model design. We discuss our fabric-based interactive system and key design considerations for using fabric-based input.

Anamary Leal; Doug A. Bowman

2012-01-01

394

Determination of an image point on a surface based on a plane-based algorithm  

NASA Astrophysics Data System (ADS)

Constitutive models of particulate materials often rely on distances between the current stress state in stress space and various surfaces. Examples of these surfaces include the bounding surface and the dilatancy surface. This paper proposes a rigorous method for determination of distance to a surface in stress space. It starts by examining operations on stress variables defined in the plane. Algorithms for determination of an image point on a surface are then presented as a function of the location of the current stress state with respect to the surface. For points within the surface, the bisection method is used; otherwise, the secant method is used. The paper shows that implementation of the proposed algorithm locates the image point on a surface in stress space with accuracy and rigor, providing an accurate measure of the distance to the surface that can be used in hardening or flow rules.

Woo, Sang Inn; Salgado, Rodrigo

2014-05-01

395

Grinding surface roughness measurement based on the co-occurrence matrix of speckle pattern texture  

NASA Astrophysics Data System (ADS)

Surface speckle pattern intensity distribution resulting from laser light scattering from a rough surface contains various information about the surface geometrical and physical properties. A surface roughness measurement technique based on the texture analysis of surface speckle pattern texture images is put forward. In the surface roughness measurement technique, the speckle pattern texture images are taken by a simple setup configuration consisting of a laser and a CCD camera. Our experimental results show that the surface roughness contained in the surface speckle pattern texture images has a good monotonic relationship with their energy feature of the gray-level co-occurrence matrices. After the measurement system is calibrated by a standard surface roughness specimen, the surface roughness of the object surface composed of the same material and machined by the same method as the standard specimen surface can be evaluated from a single speckle pattern texture image. The robustness of the characterization of speckle pattern texture for surface roughness is also discussed. Thus the surface roughness measurement technique can be used for an in-process surface measurement.

Lu, Rong-Sheng; Tian, Gui-Yun; Gledhill, Duke; Ward, Steve

2006-12-01

396

The effect of tooth bleaching on the shear bond strength of orthodontic brackets using self-etching primer systems  

PubMed Central

Objective: The purpose of this study was to determine the effect of 10% carbamide peroxide and 38% hydrogen peroxide bleaching agents on the shear bond strength of orthodontic brackets using self-etching primer systems. Methods: Forty five freshly extracted human premolar teeth were randomly divided into 3 groups of 15 teeth each: control (group 1), 10% carbamide peroxide at-home bleached (group 2), and 38% hydrogen peroxide in-office bleached (group 3). Three weeks later, all brackets were bonded using a self-etching primer system. The shear bond strength of these brackets was measured and recorded in MPa. Adhesive remnant index (ARI) scores were determined after the brackets failed. Data were analyzed using Kruskal- Wallis test, pairwise comparisons were made using the Mann-Whitney U test and ARI scores were analyzed using a chi-square test at a significance level of P<.05. Results: The shear bond strengths of group 1 (mean: 17.7 ± 9.7 MPa) were significantly higher (P<.05) than those of group 3 (mean: 9.9 ± 5.4 MPa). No significant differences were found between group 2 (mean: 12.3 ± 4.7) and either group 1 or group 3 (P>.05). ARI scores did not differ significantly among the 3 groups. Conclusions: The use of 10% carbamide peroxide bleaching does not significantly reduce shear bond strength values. In contrast, use of 38% hydrogen peroxide bleaching significantly reduces these values.

Akin, Mehmet; Aksakalli, Sertac; Basciftci, Faruk Ayhan; Demir, Abdullah

2013-01-01

397

Effect of a self-etch primer\\/adhesive on the shear bond strength of orthodontic brackets  

Microsoft Academic Search

Conventional adhesive systems use 3 different agents (an enamel conditioner, a primer solution, and an adhesive resin) during the bonding of orthodontic brackets to enamel. A unique characteristic of some new bonding systems in operative dentistry is that they combine the conditioning and priming agents into a single product. Combining conditioning and priming saves time and should be more cost-effective

Samir E. Bishara; Leigh VonWald; John F. Laffoon; John J. Warren

2001-01-01

398

Metal Work--Making a Hanging Basket Bracket. Kit No. 22. Instructor's Manual [and] Student Learning Activity Manual.  

ERIC Educational Resources Information Center

An instructor's manual and student activity guide on making a hanging basket bracket are provided in this set of prevocational education materials which focuses on the vocational area of trade and industry (metal work). (This set of materials is one of ninety-two prevocational education sets arranged around a cluster of seven vocational offerings:…

White, Jim

399

Sonar Dome and a Mounting Bracket for Removably Connecting an Acoustic Sensor Element to a Sonar Dome.  

National Technical Information Service (NTIS)

A mounting bracket for removably connecting an acoustic sensor element to an inside wall of a sonar dome of a marine vessel includes a first protrusion bonded at a first end thereof to the inside wall of the sonar dome, extending inwardly therefrom, and p...

T. S. Ramotowski

2004-01-01

400

Automatic Magnetic Particle Inspection System for the Bracket Welds of Atucha i Nuclear Power Plant Pressure Vessel  

Microsoft Academic Search

The present work refers to the welding inspection of the brackets of Atucha I Nuclear Power Plant's Pressure Vessel (RPV) using the wet fluorescent magnetic particles technique (MT). Due to limited access and high radiation levels in the inspection area, it was necessary to automate the testing and use non conventional magnetization techniques. This paper describes the design and implementation

P. Katchadjian; C. Desimone; A. Garcia; C. Antonaccio; F. Schroeter; P. Mastroleonardo

2011-01-01

401

An examination of the effects of levelingwith nickel titanium rectangular arch wires combined with torqued incisor brackets  

Microsoft Academic Search

Leveling the curve of Spee with sequential round cross-section arch wires characteristically results in incisor proclination. To prevent this, the use of low modulus, rectangular cross-section arch wires combined with torqued incisor brackets has been recommended by some clinicians. Clinical data were analyzed to determine whether this is the case. It showed that proclination does occur at a lesser angle

Stanley Braun

2001-01-01

402

Accurate evaluation of free-form surface profile error based on quasi particle swarm optimization algorithm and surface subdivision  

NASA Astrophysics Data System (ADS)

Although significant progress has been made in precision machining of free-form surfaces recently, inspection of such surfaces remains a difficult problem. In order to solve the problem that no specific standards for the verification of free-form surface profile are available, the profile parameters of free-form surface are proposed by referring to ISO standards regarding form tolerances and considering its complex