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1

Effect of different surface treatments for ceramic bracket base on bond strength of rebonded brackets.  

PubMed

The aim of this study was to evaluate the shear bond strength of rebonded ceramic brackets after subjecting the bracket base to different treatments. Seventy-five premolars were selected and randomly distributed into five groups (n=15), according to the type of the bracket surface treatment: I, no treatment, first bonding (control); II, sandblasting with aluminum oxide; III, sandblasting + silane; IV, silica coating + silane; and V, silicatization performed in a laboratory (Rocatec system). The brackets were fixed on an enamel surface with Transbond XT resin without acid etching. The brackets were then removed and their bases were subjected to different treatments. Thereafter, the brackets were fixed again to the enamel surface and the specimens were subjected to shear bond strength (SBS) test. The adhesive remnant index (ARI) was then evaluated for each specimen. Data were subjected to ANOVA and Tukey's tests (?=0.05). A statistically significant difference was observed only between Rocatec and the other groups; the Rocatec group showed the lowest SBS values. The highest SBS values were observed for group 1, without any significant difference from the values for groups II, III and IV. Most groups had a higher percentage of failures at the enamel-resin interface (score 1). It was concluded that the surface treatments of rebonded ceramic brackets were effective, with SBS values similar to that of the control group, except Rocatec group. PMID:25672386

Guarita, Monique Kruger; Moresca, Alexa Helena Köhler; Losso, Estela Maris; Moro, Alexandre; Moresca, Ricardo Cesar; Correr, Gisele Maria

2015-01-01

2

The relationship between bond strength and orthodontic bracket base surface area with conventional and microetched foil-mesh bases  

Microsoft Academic Search

The aim of this study was to test the effects on the shear bond strength by sandblasting bracket base surfaces, reducing base surface area, and etching enamel with various acid types. Four different base sizes, used as either standard (untreated), sandblasted or microetched were bonded with Phase II resin (Reliance Orthodontic Products, Inc.) in four groups of 12 bovine enamel

G. A. MacColl; P. E. Rossouw; K. C. Titley; C. Yamin

1998-01-01

3

Improvements in bracket base design.  

PubMed

Acid etch bonding of orthodontic attachments to the labial and lingual surfaces of teeth is generally adequate for clinical service. Failures do occur, and these are related to technique problems in acid etching or resin manipulation or to bracket base design. The widely used foil mesh base can present problems in retention because of design defects or corrosion. Improvement in mechanical retention of resin to the attachment base would result in significant improvements in bonding and fewer clinical failures. One of our approaches to improved retention is to fuse metallic or ceramic particles onto the bracket base so as to achieve a particulate or porous layer into which resin can penetrate. The results of bond-strength tests showed that a 100 percent increase in bond strength could be obtained with sintered porous metal-coated brackets. Further development is proceeding. PMID:6340515

Smith, D C; Maijer, R

1983-04-01

4

Comparative evaluation of ceramic bracket base designs.  

PubMed

Since the initial introduction of ceramic brackets, base designs have been modified to reduce tooth damage during debonding. The purpose of this study was to compare shear and tensile bond strengths and fracture sites of four second-generation ceramic brackets: Allure IV (A) (GAC International, Inc., Central Islip, N.Y.), Ceramaflex (C) (TP Orthodontics, Inc., LaPorte, Ind.), Intrigue (I) (Lancer Orthodontics, Carlsbad, Calif.), Transcend 2000 (T) (Unitek Corp., Monrovia, Calif.), and a foil-mesh base stainless steel bracket, DynaBond II (D) (Unitek Corp., Monrovia, Calif.). Twenty brackets of each type were bonded to 100 mandibular bovine incisor teeth with Concise bonding adhesive. The samples were thermocycled for 24 hours and the brackets were debonded with an Instron universal testing machine (Instron Corp., Canton, Mass.). A modified Transcend debonding instrument was used for tensile debonding, whereas a chisel was used for shear debonding. An analysis of variance was performed with a 0.05 level of confidence. Mean shear strengths (kg/cm2) necessary to debond were 174.0 (A), 71.0 (C), 189.0 (I), 228.0 (T), and 160.0 (D). Mean tensile strengths (kg/cm2) were 27.0 (A), 26.7 (C), 51.3 (I), 56.5 (T), and 48.6 (D). Fracture sites examined with a light microscope showed no enamel damage with any of the ceramic brackets. Intrigue was the only bracket to fracture and had 30% bracket fracture in the tensile mode and 20% bracket fracture in the shear mode. The percentage of fractures at the adhesive-bracket base interface for shear and tensile modes, respectively, were 80, 100 (A); 100, 90 (C); 10, 60 (I); 60, 90 (T); and 90, 80 (D).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8198079

Bordeaux, J M; Moore, R N; Bagby, M D

1994-06-01

5

Alternatives to ceramic brackets: the tensile bond strengths of two aesthetic brackets compared ex vivo with stainless steel foil-mesh bracket bases.  

PubMed

The mean tensile/peel bond strengths were evaluated for three types of aesthetic brackets (a ceramic-reinforced bracket and two generations of a ceramic/polycarbonate combination bracket). These were found to be significantly lower than the mean tensile/peel bond strength of a convention foil-mesh stainless steel bracket base. Failure of the ceramic-reinforced polycarbonate brackets occurred predominantly by fracture of the tie wings during testing. With the ceramic/polycarbonate combination brackets, the majority of the specimens failed due to separation of the ceramic and polycarbonate parts of the bracket. PMID:9218111

Arici, S; Regan, D

1997-05-01

6

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. PMID:23675217

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

2011-01-01

7

SHEAR BOND STRENGTH OF ORTHODONTIC BRACKETS TO ENAMEL UNDER DIFFERENT SURFACE TREATMENT CONDITIONS  

PubMed Central

The purpose of the present study was to evaluate the shear bond strength to enamel and the adhesive remnant index (ARI) of both metallic and polycarbonate brackets bonded under different conditions. Ninety bovine permanent mandibular incisors were embedded in acrylic resin using PVC rings as molds and assigned to 6 groups (n=15). In Groups 1 (control) and 3, metallic and polycarbonate orthodontic brackets were, respectively, bonded to the enamel surfaces using Transbond XT composite according to the manufacturer's recommendations. In Groups 2 and 4, both types of brackets were bonded to enamel with Transbond XT composite, but XT primer was replaced by the OrthoPrimer agent. In Groups 5 and 6, the polycarbonate bracket bases were sandblasted with 50-?m aluminum-oxide particle stream and bonded to the enamel surfaces prepared under the same conditions described in Groups 3 and 4, respectively. After bonding, the specimens were stored in distilled water at 37°C for 24 hours and then submitted to shear bond strength test at a crosshead speed of 0.5 mm/min. The results (MPa) showed no statistically significant difference between Groups 4 and 6 (p>0.05). Likewise, no statistically significant differences (p>0.05) were found among Groups 1, 2, and 5, although their results were significantly lower than those of Groups 4 and 6 (p<0.05). Group 3 had statistically significant lower bond strength than Groups 2, 4, and 6, but no statistically significant differences were found on comparison to Groups 1 and 5. A larger number of fractures at the bracket/composite interface were evidenced by the ARI scores. OrthoPrimer bonding agent yielded higher bond strength in the groups using either conventional or sandblasted polycarbonate brackets, which was not observed in the groups using metallic brackets. PMID:19089115

Pithon, Matheus Melo; de Oliveira, Márlio Vinícius; Ruellas, Antonio Carlos de Oliveira; Bolognese, Ana Maria; Romano, Fábio Lourenço

2007-01-01

8

Comparison surface characteristics and chemical composition of conventional metallic and nickel-free brackets.  

PubMed

This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracket surface was performed using SEM, whereby surface features were described and compared. The elemental composition was analyzed by EDS. According to surface analysis, groups ABZ and RL showed a homogeneous surface, with better finishing, whereas the surfaces in groups NF and RM were rougher. The chemical components with the highest percentage were Fe, Cr and C. Groups NF and MR showed no nickel in their composition. In conclusion, the bracket surface of the ABZ and RL groups was more homogeneous, with grooves and pores, whereas the surfaces in groups NF and RM showed numerous flaws, cracks, pores and grooves. The chemical composition analysis confirmed that the nickel-free brackets had no Ni in their composition, as confirmed by the manufacturer's specifications, and were therefore safe to use in patients with a medical history of allergy to this metal. PMID:25590508

Shintcovsk, Ricardo Lima; Knop, Luegya Amorim Henriques; Gandini, Luiz Gonzaga; Martins, Lidia Parsekian; Pires, Aline Segatto

2015-01-01

9

Effects of self-ligating brackets on the surfaces of stainless steel wires following clinical use: AFM investigation.  

PubMed

In orthodontic treatment, the frictional force between the archwire and bracket reduces the effectiveness of orthodontic treatment. The frictional force is affected not only by the geometry of the self-ligating brackets but also by physical changes between the bracket slots and archwire surfaces during sliding movement. This study examined quantitatively the effect of self-ligating treatments on the surfaces of stainless steel (SS) archwires during tooth movement in vivo by atomic force microscopy. Orthodontic 0.019? × 0.025? SS archwires after clinical use with the first bicuspid-extraction treatment were employed using the Damon 3MX(®) SS self-ligating brackets, Clippy-C(®) ceramic self-ligating brackets, and Kosaka(®) SS brackets. Intact SS archwires were used as the control group. All SS archwires after clinical use showed severe scratches and significantly higher roughness caused by frictional interactions between the brackets and archwires (p < 0.0001 vs. control). The descending order of surface roughness was the SS archwires treated, with ceramic self-ligating brackets, with conventional SS brackets, and with SS self-ligating brackets (p < 0.001). These findings suggest that an orthodontic treatment with SS self-ligating brackets may require smaller orthodontic forces than that with ceramic self-ligating brackets or conventional SS brackets. PMID:22188518

Choi, S; Joo, H-J; Cheong, Y; Park, Y-G; Park, H-K

2012-04-01

10

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. PMID:23984339

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

2013-01-01

11

Collision and intersection detection of two ruled surfaces using bracket method  

Microsoft Academic Search

Collision and intersection detection of surfaces is an important problem in computer graphics and robotic engineering. A key idea of our paper is to use the bracket method to derive the necessary and sufficient conditions for the collision of two ruled surfaces. Then the numerical intersection curve can be characterized. The cases for two bounded ruled surfaces are also discussed.

Ying Chen; Li-Yong Shen; Chun-Ming Yuan

2011-01-01

12

The Application Based on Bracket Method for Planar Computational Geometry  

Microsoft Academic Search

In this paper, we study two basic problems about planar computational geometry with bracket method. One is how to judge whether a point is inside a given convex polygon, the other is how to compute the convex hull of planar points. The key idea of our criteria is to use the bracket, which is made up of the homogeneous coordinates

Ying Chen; Yaogang Du; Chunming Yuan

2009-01-01

13

Effects of light-emitting diode and halogen light curing techniques on ceramic brackets bonded to porcelain surfaces.  

PubMed

The objectives of this study were to test the efficiency of LED curing devices in bonding ceramic brackets to porcelain surfaces and to compare the effects of LED and halogen curing techniques on shear bond strength of ceramic brackets. A total of 20 glazed porcelain facets were randomly divided into two groups of 10. Porcelain surfaces were etched with 9.6% hydrofluoric acid for 2 minutes, and silane was applied on the etched porcelain surface. Ceramic brackets were bonded with an LC composite resin cured with soft start mode LED and a halogen light. Bond strengths, as determined in the shear mode, were higher in the LED group (P < .001). LED curing units with the soft start polymerization mode were more effective than halogen curing units in bonding ceramic brackets on porcelain surfaces. The type of curing light must be considered as an important factor affecting bond strength of ceramic brackets on porcelain surfaces. PMID:16808576

Türkkahraman, Hakan; Küçüke?men, H Cenker

2006-07-01

14

Lens design based on lens form parameters using Gaussian brackets  

NASA Astrophysics Data System (ADS)

The optical power distribution and the symmetry of the lens components are two important attributes that decide the ultimate lens performance and characteristics. Lens form parameters W and S are the key criteria describing the two attributes mentioned above. Lens components with smaller W and S will have a good nature of aberration balance and perform well in providing good image quality. Applying the Gaussian brackets, the two lens form parameters and the Seidel Aberration Coefficients are reconstructed. An initial lens structure can be analytically described by simultaneous equations of Seidel Aberration Coefficients and third-order aberration theory. Adding the constraints of parameters W and S in the solving process, a solution with a proper image quality and aberration distribution is achieved. The optical properties and image quality of the system based on the parameters W and S are also analyzed in this article. In the method, the aberration distribution can be controlled to some extent in the beginning of design, so that we can reduce some workload of optimization later.

Yuan, Xiangyu; Cheng, Xuemin

2014-11-01

15

Influence of surface treatments on the shear bond strength of orthodontic brackets to porcelain  

Microsoft Academic Search

The purpose of this study was to investigate the effect of various surface treatments after different storage time and thermocycling on the shear bond strength of orthodontic brackets to the feldspathic porcelain surfaces. 128 disc-shaped porcelain specimens were randomly assigned to the following surface treatments: 9.6% HFA, 9.6% HFA combined with silane, 50 ? aluminum trioxide sandblasting followed by silane

Cong Wang; Jishan Zeng; Shaoan Wang; Zheng Yang; Qian Huang; Pixiu Chen; Shujuan Zhou; Xiaoqing Liu

2008-01-01

16

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. PMID:23814707

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

2013-01-01

17

Shear bond resistance and enamel surface comparison after the bonding and debonding of ceramic and metallic brackets  

PubMed Central

Objective To evaluate, in vitro, the shear bond strength presented by three brands of polycrystalline ceramic brackets and one brand of metallic bracket; verify the adhesive remnant index (ARI) after the tests, and analyze, through scanning electron microscopy (SEM) the enamel surface topography after debonding, detecting the release of mineral particles. Methods Sixty bovine lower incisors were used. Three ceramic brackets (Allure®, InVu®, and Clarity®) and one metallic bracket (Geneus®) were bonded with Transbond XT®. Kruskal-Wallis's test (significance level set at 5%) was applied to the results of share bond and ARI. Mann Whitney's test was performed to compare the pairs of brackets in relation to their ARI. Brown-Forsythe's test (significance level set at 5%) was applied to the results of enamel chemical composition. Comparisons between groups were made with Games-Howell's and the Post-hoc tests. Results No statistically significant difference was observed in relation to the shear bond strength loads. Clarity® brackets were the most affected in relation to the surface topography and to the release of mineral particles of enamel (calcium ions). Conclusion With regard to the ARI, there was a prevalence of score 4 (40.4%). As for enamel surface topography, the Geneus® bracket was the only one which did not show superficial tissue loss. The InVu® and Clarity® ones showed cohesive fractures in 33.3% and the Allure® in 50%, the latter being the one that presented most fractures during removal. PMID:24713563

da Rocha, José Maurício; Gravina, Marco Abdo; Campos, Marcio José da Silva; Quintão, Cátia Cardoso Abdo; Elias, Carlos Nelson; Vitral, Robert Willer Farinazzo

2014-01-01

18

Porcelain surface-conditioning techniques and the shear bond strength of ceramic brackets.  

PubMed

The aim of this study was to compare the effects of various porcelain surface-conditioning techniques, used either alone or in combination, on the shear bond strength (SBS) of ceramic brackets cured with a light emitting diode (LED). Thirty glazed porcelain facets were randomly divided into three groups of 10. In group I, the porcelain surfaces were etched with 9.6 per cent hydrofluoric acid (HFA) for 2 minutes before silane application, in group II, the porcelain surfaces were sandblasted with aluminium oxide particles, etched with 9.6 per cent HFA for 2 minutes, and silane applied, and in group III, the porcelain surfaces were sandblasted with aluminium oxide particles before silane application. Spirit ceramic brackets were bonded with a light-cured composite resin (Light Bond) and a LED. All specimens were stored in distilled water at 37 degrees C for 24 hours and thermocycled. Bond strength was determined in shear mode at a crosshead speed of 0.5 mm/minute until fracture occurred. Analysis of variance indicated a significant difference between groups (P < 0.001). The lowest SBS was found in group III (5.46 +/- 1.34, P < 0.001). No significant difference was found between group I (11.38 +/- 1.65) and group II (10.45 +/- 1.15; P > 0.05). Surface treatment with HFA and a silane coupling agent produced the highest bond strength. Sandblasting before HFA and silane application did not significantly increase bond strength. Silane application to sandblasted porcelain provided poor results in vitro and clinical trials are needed to determine its reliability for bonding ceramic brackets to ceramic crowns. PMID:16916898

Türkkahraman, Hakan; Küçükesmen, H Cenker

2006-10-01

19

Effects of silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets  

PubMed Central

Objective The aim of this study was to evaluate the effects of tribochemical silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets. Material and Methods Twenty debonded metal and 20 debonded ceramic brackets were randomly assigned to receive one of the following surface treatments (n=10 for each group): (1) sandblasting (control); (2) tribochemical silica coating combined with silane. Brackets were rebonded to the enamel surface on the labial and lingual sides of premolars with a light-polymerized resin composite. All specimens were stored in distilled water for 1 week and then thermocycled (5,000 cycles) between 5-55°C. Shear bond strength values were measured using a universal testing machine. Student's t-test was used to compare the data (?=0.05). Failure mode was assessed using a stereomicroscope, and the treated and non-treated bracket surfaces were observed by scanning electron microscopy. Results Rebonded ceramic brackets treated with silica coating followed by silanization had significantly greater bond strength values (17.7±4.4 MPa) than the sandblasting group (2.4±0.8 MPa, P<0.001). No significant difference was observed between the rebonded metal brackets treated with silica coating with silanization (15±3.9 MPa) and the sandblasted brackets (13.6±3.9 MPa). Treated rebonded ceramic specimens primarily exhibited cohesive failure in resin and adhesive failure at the enamel-adhesive interface. Conclusions In comparison to sandblasting, silica coating with aluminum trioxide particles followed by silanization resulted in higher bond strengths of rebonded ceramic brackets. PMID:21625739

ATSÜ, Saadet; ÇATALBA?, Bülent; GELGÖR, ?brahim Erhan

2011-01-01

20

Bracket for photovoltaic modules  

DOEpatents

Brackets for photovoltaic ("PV") modules are described. In one embodiment, a saddle bracket has a mounting surface to support one or more PV modules over a tube, a gusset coupled to the mounting surface, and a mounting feature coupled to the gusset to couple to the tube. The gusset can have a first leg and a second leg extending at an angle relative to the mounting surface. Saddle brackets can be coupled to a torque tube at predetermined locations. PV modules can be coupled to the saddle brackets. The mounting feature can be coupled to the first gusset and configured to stand the one or more PV modules off the tube.

Ciasulli, John; Jones, Jason

2014-06-24

21

Shear-bond-strength of orthodontic brackets to aged nano-hybrid compositeresin surfaces using different surface preparation.  

PubMed

The aim of this study was to evaluate the effects of different surface preparation methods on the shear bond strength (SBS) of orthodontic metal brackets to aged nano-hybrid resin composite surfaces in vitro. A total of 100 restorative composite resin discs, 6 mm in diameter and 3 mm thick, were obtained and treated with an ageing procedure. After ageing, the samples were randomly divided as follows according to surface preparation methods: (1)Control, (2)37% phosphoric acid gel, (3)Sandblasting, (4)Diamond bur, (5)Air-flow and 20 central incisor teeth were used for the control etched group. SBS test were applied on bonded metal brackets to all samples. SBS values and residual adhesives were evaluated. Analysis of variance showed a significant difference (p<0.001) between the groups. Sandblasted group had the highest SBS value (12.85 MPa) in experimental groups. The sandblasting surface treatment is recommended as an effective method of bonding orthodontic metal brackets to nano-hybrid composite resin surfaces. PMID:25748463

Demirtas, Hatice Kubra; Akin, Mehmet; Ileri, Zehra; Basciftci, Faruk Ayhan

2015-01-01

22

Comparison of bond strength between simple foil mesh and laser-structured base retention brackets  

Microsoft Academic Search

The aims of the current study were to evaluate the bond strength of a new metallic orthodontic bracket with a laser structured base (Discovery, Dentaurum, Ispringen, Germany), and its effects on the site of bond failure and on the behavior of the enamel after debonding. One hundred and twenty recently extracted human premolars were bonded with 1 of 2 types

Olivier Sorel; Rafeh El Alam; Francis Chagneau; Guy Cathelineau

2002-01-01

23

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

PubMed

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-microm) or rough (125-microm) diamond bur, sandblasting (50-microm or 110-microm aluminum oxide [Al2O3]), and silica coating (30-microm silica). Fifty disc-shaped specimens of 5 different alloys (gold-silver, palladium-silver, nickel-chromium, cobalt-chromium, and titanium) were ground with 1200-grit silicone carbide abrasive and polished before being reused for each conditioning method. Polished surfaces were used as negative controls. After measuring surface roughness (RZ), metal brackets were bonded to the conditioned alloys with a self-curing resin composite. Specimens were thermocycled (5000 times, 5 degrees-55 degrees C, 30 seconds), and shear bond tests were performed. Significantly higher (P<.001) surface roughnesses were observed with use of the rough diamond bur (RZ approximately 33 microm), 110-microm Al2O3 (RZ approximately 14 microm), and fine diamond bur (RZ approximately 10 microm), compared with the controls (RZ approximately 1 microm). Silica coating (RZ approximately 4 microm) and 50-microm Al2O3 (RZ approximately 4 microm) demonstrated no significant difference (P>.001) in roughness when compared with the controls. The control group showed no resistance to shear forces (0 MPa). Bond values were greater (19 MPa) when silica coating was used, compared with 50-microm Al2O3 (7 MPa) and 110-microm Al2O3 (8 MPa) for all alloys tested. However, interaction between alloys and conditioning methods exhibited significant differences (P<.0001). PMID:14718878

Nergiz, Ibrahim; Schmage, Petra; Herrmann, Wolfram; Ozcan, Mutlu

2004-01-01

24

Bond strengths of two integral bracket-base combinations: an in vitro comparison with foil-mesh.  

PubMed

The tensile/peel and shear/peel bond strengths of a cast integral bracket-base were compared with a machined integral base and a foil-mesh base. The bases were tested with both a 'no-mix' and a two-paste adhesive. The cast base performed significantly better than the other two. All the bases produced a higher bond strength when subjected to a shear mode of loading and greater bond strengths were obtained with both loading configurations when using the two-paste adhesive. These differences in bond strength between the bases cannot be explained in terms of the differences in the surface areas of the bases, so that other factors will need to be considered. PMID:2670589

Regan, D; van Noort, R

1989-05-01

25

In vitro orthodontic bracket bonding to porcelain.  

PubMed

This in vitro study investigated the influence of using different combinations of bracket, adhesive, and light-curing source on the tensile bond strength to porcelain and on failure patterns at debonding. Tensile tests were performed using: one ceramic bracket versus one metal bracket, two orthodontic composites; type bisphenol A-glycidyldimethacrylate and urethane dimethacrylate (UDMA), and four light-curing units with the same range of emission spectrum but various light intensities: three light-emitting diode (LED) units and one halogen-based unit. One hundred and sixty porcelain samples were randomly divided into 16 equal groups. The porcelain surface was conditioned with 9 per cent hydrofluoric acid before silane application. The composite was photo-polymerized for 40 seconds. After storage in water at 37°C for 24 hours, the samples were subjected to tensile force until bond failure. Bond strength and bond failure mode were recorded; results were analysed (? = 0.05) using R language; linear model with constant variance for the bond strength and multinomial distribution for the failure mode. The bond strength in all groups was sufficient to withstand orthodontic treatment (>6 MPa). There was no statistical difference between the adhesives, but comparing bracket × light interaction, it was significantly higher with the ceramic bracket. No significant differences were seen between the metal bracket groups, but for the ceramic bracket, the results were significantly higher with the LED light. No fracture was observed in porcelain with the metal bracket but it occurred in 35 per cent of the ceramic bracket samples and the risk was higher when using UDMA composite and lower with LED high intensity light. PMID:21447780

Al-Hity, R; Gustin, M-P; Bridel, N; Morgon, L; Grosgogeat, B

2012-08-01

26

El diseño del bracket lingual  

Microsoft Academic Search

Summary It wakes an study of the different bracket that it's been used in lingual orthodontics, going on with on investigation, by scanning techniques of the two types of brackets must used actually. Spacially on it's adhesion surfaces to the tooth. We have faud that the studied surfaces differences between them but not too much important. We can get to

V. Olmos; A. Victoria Fuster; M. Montesinos

27

Shear bond strength of ceramic brackets with chemical or mechanical retention.  

PubMed

The study was undertaken to measure and compare the shear bond strengths of a ceramic bracket with chemical retention, a ceramic bracket with a new type of textured base providing mechanical retention, and a metal bracket with foil-mesh base. The tests were performed on 51 extracted human premolars which were randomly divided into three equally large groups (n = 17)--one group for each type of bracket. After debonding, the site of failure was noted and the enamel surface inspected with scanning electron microscopy. The ceramic bracket with chemical retention exhibited significantly higher bond strength than the corresponding bracket with textured base. In comparison with the metal bracket significantly higher bond strengths were recorded for both types of ceramic brackets. The ceramic bracket with mechanical retention and the metal bracket were comparable as regards the site of bond failure. In some cases the chemical bond provided very high values of bond strength. Enamel failure were recorded in three teeth which had been bonded with this type of ceramic bracket. PMID:1390574

Forsberg, C M; Hagberg, C

1992-08-01

28

Metallurgical characterization of orthodontic brackets produced by Metal Injection Molding (MIM).  

PubMed

The aim of this study was to investigate the bonding base surface morphology, alloy type, microstructure, and hardness of four types of orthodontic brackets produced by Metal Injection Molding technology (Discovery, Extremo, Freedom, and Topic). The bonding base morphology of the brackets was evaluated by scanning electron microscopy (SEM). Brackets from each manufacturer were embedded in epoxy resin, and after metallographic grinding, polishing and coating were analyzed by x-ray energy-dispersive spectroscopic (EDS) microanalysis to assess their elemental composition. Then, the brackets were subjected to metallographic etching to reveal their metallurgical structure. The same specimen surfaces were repolished and used for Vickers microhardness measurements. The results were statistically analyzed with one-way analysis of variance and Student-Newman-Keuls multiple comparison test at the 0.05 level of significance. The findings of SEM observations showed a great variability in the base morphology design among the brackets tested. The x-ray EDS analysis demonstrated that each bracket was manufactured from different ferrous or Co-based alloys. Metallographic analysis showed the presence of a large grain size for the Discovery, Freedom, and Topic brackets and a much finer grain size for the Extremo bracket. Vickers hardness showed great variations among the brackets (Topic: 287 +/- 16, Freedom: 248 +/- 13, Discovery: 214 +/- 12, and Extremo: 154 +/- 9). The results of this study showed that there are significant differences in the base morphology, composition, microstructure, and microhardness among the brackets tested, which may anticipate significant clinical implications. PMID:16448250

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

2005-11-01

29

Effects of surface-conditioning methods on shear bond strength of brackets bonded to different all-ceramic materials.  

PubMed

The aims of this study were to investigate the effects of two surface-conditioning methods on the shear bond strength (SBS) of metal brackets bonded to three different all-ceramic materials, and to evaluate the mode of failure after debonding. Twenty feldspathic, 20 fluoro-apatite, and 20 leucite-reinforced ceramic specimens were examined following two surface-conditioning methods: air-particle abrasion (APA) with 25 ?m Al(2)O(3) and silica coating with 30 ?m Al(2)O(3) particles modified by silica. After silane application, metal brackets were bonded with light cure composite and then stored in distilled water for 1 week and thermocycled (×1000 at 5-55°C for 30 seconds). The SBS of the brackets was measured on a universal testing machine. The ceramic surfaces were examined with a stereomicroscope to determine the amount of composite resin remaining using the adhesive remnant index. Two-way analysis of variance, Tukey's multiple comparison test, and Weibull analysis were used for evaluation of SBS. The lowest SBS was with APA for the fluoro-apatite ceramic (11.82 MPa), which was not significantly different from APA for the feldspathic ceramic (13.58 MPa). The SBS for the fluoro-apatite ceramic was significantly lower than that of leucite-reinforced ceramic with APA (14.82 MPa). The highest SBS value was obtained with silica coating of the leucite-reinforced ceramic (24.17 MPa), but this was not significantly different from the SBS for feldspathic and fluoro-apatite ceramic (23.51 and 22.18 MPa, respectively). The SBS values with silica coating showed significant differences from those of APA. For all samples, the adhesive failures were between the ceramic and composite resin. No ceramic fractures or cracks were observed. Chairside tribochemical silica coating significantly increased the mean bond strength values. PMID:21228120

Saraç, Y ?inasi; Külünk, Tolga; Elekda?-Türk, Selma; Saraç, Duygu; Türk, Tamer

2011-12-01

30

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. PMID:24790708

Shahabi, Mostafa; Mohamadipour, Hamideh; Moosavi, Horieh

2014-01-01

31

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

PubMed

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. PMID:23355777

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

2013-01-01

32

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. PMID:23355777

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

2013-01-01

33

Intraoral corrosion of self-ligating metallic brackets and archwires and the effect on friction  

NASA Astrophysics Data System (ADS)

The purpose of this study was to investigate how the frictional coefficient was affected due to intraoral use. A secondary aim of this study was to determine whether or not there was a relationship between corrosion of orthodontic alloys and friction via scanning electron microscopic qualitative analysis. Orthodontic brackets and 0.019 x 0.025 inch stainless steel archwires were collected and divided into three groups of n=10: used bracket and used wires (UBUW), used brackets and new wires (UBNW), and new brackets and new wires (NBNW). New materials were as-received from the manufacturer, and used materials were clinically used bracket and wires collected from patients following orthodontic treatment. Archwires were pulled through bracket slots at a rate of 0.5mm/min while friction forces were measured. Following a cleaning process, the surface topography of the bracket slots was examined under a scanning electron microscope (SEM). Based on a 1-factor MANOVA, there was no significant group effect (all p>0.05) on frictional forces. Partial eta squared values indicated that intraoral exposure had only a small effect on frictional forces (? 3%). Qualitative analysis of SEM images did not show an association between surface characteristics of the bracket slots and magnitude of frictional force. Results suggest that surface corrosion from intraoral use does not significantly affect friction at the bracket wire interface.

Tima, Lori Lynn

34

The tensile bond strength of new and rebonded stainless steel orthodontic brackets.  

PubMed

The study investigated the effect on the tensile/peel bond strength of the variables associated with the bracket base, the enamel surface, and the type of adhesive when both new and used brackets were rebonded to a previously bonded enamel surface. The tensile/peel bond strength was firstly evaluated for three different types of stainless steel orthodontic bracket/base combinations. The cast integral base gave a significantly lower bond strength than the foil-mesh and photo-etched bases. Following debonding, a group of new brackets were bonded to the teeth using a chemically-activated or a light-cured adhesive. The old adhesive had been removed from the enamel by either a hand scaler or a tungsten-carbide bur. The rebonded new brackets demonstrated a small, but statistically significant fall in bond strength. No differences were found between the enamel preparations or the adhesives. A further group of previously debonded brackets were rebonded to the same teeth. The bracket bases were prepared by either smoothing with a green stone or heating in a bunsen flame followed by sandblasting and electropolishing. Highly significant falls in bond strength were obtained with all the bases. No significant differences were found between the two methods of bracket preparation. PMID:8500538

Regan, D; LeMasney, B; van Noort, R

1993-04-01

35

Rebonding performance of different ceramic brackets conditioned with a new silane coupling agent.  

PubMed

The objective of this study was to investigate the rebonding effect of a new silane coupling agent on various ceramic brackets bonded to ceramic specimen. Different ceramic brackets (Fascination 2, Clarity SL, and In-OvationC) were assigned to three groups: rebonding with new silane coupling agent, rebonding with conventional silane coupling agent, or regular bonding as control (n = 16). Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was evaluated using the adhesive remnant index score. One-way analysis of variance was applied for inferential statistics. Rebonding with the new silane coupling agent resulted in high shear bond strengths (SBSs; mean values: 37.44-41.24 MPa) and ceramic specimen fractures. Rebonding with the conventional silane coupling agent resulted in significantly (P < 0.001) lower clinically adequate SBS (mean values: 20.20-29.92 MPa) with the least ceramic specimen fractures. Regularly bonded ceramic brackets resulted in clinically adequate to high SBS (mean values: 17.06-41.56 MPa) depending on their bracket base design. Rebonded ceramic brackets showed sufficient SBS to ceramic specimen surfaces. However, increased bracket adhesion was associated with a risk of ceramic specimen surface damage. Therefore, ceramic brackets rebonded with the new silane coupling should be debonded cautiously using alternative debonding methods. PMID:21926314

Falkensammer, Frank; Jonke, Erwin; Bertl, Michael; Freudenthaler, Josef; Bantleon, Hans Peter

2013-02-01

36

A comparative study of frictional force in self-ligating brackets according to the bracket-archwire angulation, bracket material, and wire type  

PubMed Central

Objective This study aimed to compare the frictional force (FR) in self-ligating brackets among different bracket-archwire angles, bracket materials, and archwire types. Methods Passive and active metal self-ligating brackets and active ceramic self-ligating brackets were included as experimental groups, while conventional twin metal brackets served as a control group. All brackets were maxillary premolar brackets with 0.022 inch [in] slots and a -7° torque. The orthodontic wires used included 0.018 round and 0.019 × 0.025 in rectangular stainless steel wires. The FR was measured at 0°, 5°, and 10° angulations as the wire was drawn through the bracket slots after attaching brackets from each group to the universal testing machine. Static and kinetic FRs were also measured. Results The passive self-ligating brackets generated a lower FR than all the other brackets. Static and kinetic FRs generally increased with an increase in the bracket-archwire angulation, and the rectangular wire caused significantly higher static and kinetic FRs than the round wire (p < 0.001). The metal passive self-ligating brackets exhibited the lowest static FR at the 0° angulation and a lower increase in static and kinetic FRs with an increase in bracket-archwire angulation than the other brackets, while the conventional twin brackets showed a greater increase than all three experimental brackets. Conclusions The passive self-ligating brackets showed the lowest FR in this study. Self-ligating brackets can generate varying FRs in vitro according to the wire size, surface characteristics, and bracket-archwire angulation. PMID:25667913

Lee, Souk Min

2015-01-01

37

Electron microscopy analysis of different orthodontic brackets and their adhesion to the tooth enamel.  

PubMed

This study proposed to evaluate the surface morphology of different types of orthodontic brackets and the characteristics of their adhesion to the tooth enamel. There have been taken into study six metallic, five ceramic and one polymeric bracket from different brands (Ormco, Lancer, Leone, Damon, 3M, Ultradent, American Orthodontics, Rocky Mountain). The surface base of the each bracket it have been ESEM analyzed using scanning electron microscope Phillips XL-30 ESEM. There have been investigated several parameters that have a potential influence of the bracket-bonding agent interface joint: chemical composition, roughness, surface morphology and wideness. After ESEM analysis, the same metallic and ceramic brackets have been afterwards collated on extracted teeth and subjected to mechanical tests. After the mechanical testing, the samples were once again ESEM investigated. All fractures occurred in the area of the adhesive system, recording adhesive fractures of the tooth-composite resin and composite-bracket, cohesive fractures and both. The metallic brackets surfaces that are optima for a good adhesion is that of a mesh sand blasted and acid etched. From the esthetic brackets, the ceramic ones are superior to polymeric ones regarding bonding to teeth. PMID:25178330

Ciocan, Delia Ioana; Stanciu, Drago?; Popescu, Manuela Anca; Miculescu, Florin; Plotog, Ioan; V?rzaru, Gauden?iu; Ciocan, Lucian Toma

2014-01-01

38

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

39

The effect of surface treatment with Er: YAG laser on shear bond strength of orthodontic brackets to fiber-reinforced composite  

PubMed Central

Objectives: This study aimed to investigate the effect of surface treatment with Er:YAG laser on shear bond strength (SBS) of orthodontic brackets to fiber-reinforced composite (FRC). Study Design: Ninety human premolars were randomly divided into six groups of 15. FRC bars were bonded to the teeth with a flowable composite (FC) and then underwent following treatments. In group 1 no further treatment was performed. In group 2 the FRC surfaces were covered by FC. An Er:YAG laser was employed to treat FRCs in groups 3 ( 200 mJ/10 Hz) and 4 (300 mJ/15 Hz). The FRC strips in groups 5 and 6 were first covered by FC and then irradiated with Er:YAG laser at 200 mJ/10 Hz (group 5) or 300 mJ/15 Hz (group 6). Stainless steel brackets were bonded to FRCs using a light-cure adhesive system. After 24 hours, the samples were tested for SBS and the adhesive remnant index (ARI) scores were determined. Results: There was a significant difference in SBS among the study groups (P <0.001). Pairwise comparisons indicated that SBS was significantly lower in group 1 compared to all other groups (p<0.05) except group 2. Bond strength in group 6 was significantly greater than all the study groups (p<0.05) except group 5. No significant difference was found in ARI scores among the groups. Conclusions: Covering the FRC surface by a layer of flowable composite and then application of Er:YAG laser at 300 mJ/15 Hz could be recommended to increase bond strength of orthodontic attachments to FRC. Key words:Fiber-reinforced composite, orthodontics, Sshear bond strength, laser, Er:YAG, surface treatment, bracket, FRC. PMID:25593660

Dehghani, Mahboobe

2014-01-01

40

Longitudinal epiphyseal bracket.  

PubMed

Longitudinal epiphyseal bracket or bracket epiphysis is an uncommon disorder of growth. Alternatively known as a delta phalanx, it is due to an anomalous secondary ossification center that extends longitudinally along the diaphysis. Although rare, longitudinal epiphyseal bracket most commonly manifests in the hands as clinodactyly and in the feet as hallux varus. Previously, longitudinal epiphyseal bracket has been treated with angular osteotomy, but we recommend early surgical physiolysis. We describe this uncommon disorder, our current recommendation for treatment, and present three illustrative cases. PMID:24432108

Choo, Alexander D; Mubarak, Scott J

2013-12-01

41

The Effect of an Acidic Food-Simulating Environment on the Shear Bond Strength of Self-Ligating Brackets with Different Base Designs  

PubMed Central

Aim. This study aims to evaluate the effect of acidic food simulant and (acetic acid 3%) on the shear bond strength (SBS) and adhesive remnant index (ARI) scores of one conventional and three different self-ligating brackets with different base designs. Materials and Methods. Freshly extracted first maxillary premolars (n = 160) were embedded in resin blocks. A conventional stainless steel bracket, Equilibrium 2, and three types of self-ligating brackets, Speed, In-Ovation R, and Damon 3MX, were bonded to teeth and exposed to distilled water (groups 1, 3, 5, and 7) or acetic acid 3% (groups 2, 4, 6, 8) for 12 weeks. SBS and ARI were calculated and statistical analysis was performed with the analysis of variance (SBS) or ?2 test (ARI) to compare values between the different groups. Results. Equilibrium 2 and In-Ovation R showed a significantly lower SBS in the acidic environment than in distilled water. Significant differences in ARI scores were found for Equilibrium 2 after immersion in an acidic environment, shifting from 0 in distilled water to 2 in an acidic environment. Conclusions. Equilibrium 2 and In-Ovation R brackets showed a significant decrease in SBS after a 12-week immersion in acetic acid 3%, although all groups showed clinically acceptable SBS. Equilibrium 2 showed significant differences in ARI scores when exposed to acetic acid 3%. PMID:25328524

Sheibaninia, Ahmad; Sepasi, Sepehr; Saghiri, Mohammad Ali; Sepasi, Setareh

2014-01-01

42

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

43

An in Vitro Evaluation of Remineralization Potential of Novamin® on Artificial Enamel Sub-Surface Lesions Around Orthodontic Brackets Using Energy Dispersive X-Ray Analysis (EDX)  

PubMed Central

Objective: To evaluate and compare the Ca/P ratio of enamel samples around the orthodontic brackets for time periods of 0, 2 and 10 days in two groups (control group and study group). Materials and Methods: Forty extracted teeth were randomly divided into control group and study group. All samples were demineralized and incubated in artificial saliva at 37°C for a period of 10 days after demineralization. During this phase the enamel samples in the study group were treated with remineralizing paste (NuproNusolution containing Novamin®-Dentsply) for 10 days. At the end of the incubation period, Ca/P ratios were analyzed for both the groupsby EDX analysis. Data obtained was subjected to statistical analysis using student t-test for paired samples and Student t- test for individual samples (p ? 0.05). Results: It was found that the mean Ca/P ratio was significantly lower for the control group as compared to the study group (p-value < 0.05) after 10 d of incubation. Conclusion: Novamin® containing remineralization toothpaste showed significant remineralizing potential in inhibition of artificial enamel sub-surface lesion around bracket after 10 days of remineralization phase. EDX element analysis was found to be an efficient method to quantify the changes in mineral content of a sample during in vitro caries studies. PMID:25584326

Padmanabhan, Sridevi; Chitharanjan, Arun B

2014-01-01

44

Algebraic string bracket as a Poisson bracket  

Microsoft Academic Search

In this paper we construct a Lie algebra representation of the algebraic string bracket on negative cyclic cohomology of an associative algebra with appropriate duality. This is a generalized algebraic version of the main theorem of [AZ] which extends Goldman's results using string topology operations.The main result can be applied to the de Rham complex of a smooth manifold as

Hossein Abbaspour; Thomas Tradler; Mahmoud Zeinalian

2008-01-01

45

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

46

Comparison of the frictional resistance between archwire and different bracket system: An in vitro study  

PubMed Central

Background and Objectives: The purpose of this study is to evaluate the frictional resistance generated by conventional stainless steel, radiance ceramic bracket, self-ligating and composite brackets using a 0.019 × 0.025 stainless steel straight length wires in a 022 slot and to select brackets based on their frictional characteristic. Methodology: In order to conduct this study, four different types of bracket system were selected of the mclaughlin-bennet-trevesi (MBT) discipline. They are Group 1 - stainless steel, Group 2 - composite bracket Group 3 - (American Orthodontics) radiance ceramic bracket Group 4 - self-ligating bracket (SLB) (Empower). In this study, five maxillary brackets of an arch of each type were used. All brackets are 0.022 × 0.028 in preadjusted edgewise appliance which simulates the dental arch. Five brackets were bonded to a stainless steel bar of dimension 150 mm × 25 mm × 3 mm. The bracket-arch wire units were submitted to mechanical test with an Instron universal testing machine 3365. A testing apparatus or holding jig was designed to hold the bracket during the mechanical test. Each sample was pulled at a speed of 6 mm for 1 min. Descriptive statistical information including mean and standard deviation of maximum friction force was calculated for each bracket wire combination. Interpretation and Conclusion: The SLB has the least friction among the four groups. The ceramic bracket showed the highest friction followed by stainless steel bracket, composite bracket, and SLB. PMID:25210359

Pillai, Ajith R.; Gangadharan, Anil; Kumar, Satheesh; Shah, Anwar

2014-01-01

47

Hydrodynamic Nambu brackets derived by geometric constraints  

NASA Astrophysics Data System (ADS)

A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fractional Poisson equations for the stream-function are also included as results from the derivation. The formalism is extended to a hydrodynamic system coupled to a second degree of freedom, with the Rayleigh–Bénard convection as an example. This system is reformulated in terms of constitutive conservation laws with two additive brackets which represent individual processes: a first representing inviscid 2D hydrodynamics, and a second representing the coupling between hydrodynamics and thermodynamics. The results can be used for the formulation of conservative numerical algorithms that can be employed, for example, for the study of fronts and singularities.

Blender, Richard; Badin, Gualtiero

2015-03-01

48

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. PMID:24455081

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

2013-01-01

49

A New Bracket System for LingualOrthodontic Treatment  

Microsoft Academic Search

Background and Method: Almost 20 months of practical application of a new lingual bracket system have revealed some clinically relevant advantages and disadvantages deriving from the original design. Numerous modifications in the design of the bracket bodies and bases have contributed towards further optimization of the appliance. The efficiency of the appliance is discussed, taking five treated cases as examples.

Dirk Wiechmann

2003-01-01

50

Bond strengths evaluation of laser ceramic bracket debonding  

NASA Astrophysics Data System (ADS)

Ceramic brackets often used for an orthodontic treatment can lead to problems such as enamel tear outs because of their low fracture resistance and high bond strengths. Therefore the aim of our study was to investigate the positive laser radiation effect on bracket debonding. Moreover, the influence of the enamel shape surface under the bracket and laser radiation power on the debonding strength was investigated. The source of the radiation was the longitudinally diode-pumped Tm:YAP laser operating at 1997 nm. To eliminate the tooth surface roughness the flat enamel surface was prepared artificially and the bracket was bonded on it. The debonding was accomplished by Tm:YAP laser radiation with different the power value while recording the temperature rise in the pulp. To simulate the debonding process in vivo the actual bond strength was measured by the digital force gauge. The results were analyzed by scanning electron microscope.

Dostalová, T.; Jelinková, H.; Šulc, J.; N?mec, M.; Fibrich, M.; Jelínek, M.; Michalík, P.; Bu?ková, M.

2012-09-01

51

Preliminary Process Design of ITER ELM Coil Bracket Brazing  

NASA Astrophysics Data System (ADS)

With the technical requirement of the International Thermonuclear Experimental Reactor (ITER) project, the manufacture and assembly technology of the mid Edge Localized Modes (ELM) coil was developed by the Institute of Plasma Physics, Chinese Academy of Science (ASIPP). As the gap between the bracket and the Stainless Steel jacketed and Mineral Insulated Conductor (SSMIC) can be larger than 0.5 mm instead of 0.01 mm to 0.1 mm as in normal industrial cases, the process of mid ELM coil bracket brazing to the SSMICT becomes quiet challenging, from a technical viewpoint. This paper described the preliminary design of ELM coil bracket brazing to the SSMIC process, the optimal bracket brazing curve and the thermal simulation of the bracket furnace brazing method developed by ANSYS. BAg-6 foil (Bag50Cu34Zn16) plus BAg-1a paste (Bag45CuZnCd) solders were chosen as the brazing filler. By testing an SSMICT prototype, it is shown that the average gap between the bracket and the SSMIC could be controlled to 0.2-0.3 mm, and that there were few voids in the brazing surface. The results also verified that the preliminary design had a favorable heat conducting performance in the bracket.

LI, Xiangbin; SHI, Yi

2015-03-01

52

Friction between different wire bracket combinations in artificial saliva – an in vitro evaluation  

PubMed Central

Objective The objective this work was to assess the friction coefficient between brackets and wires of different materials under conditions simulating the oral environment. Material and Methods Stainless steel (SS) and titanium-molybdenum alloy (TMA) wires of 0.019x0.025-in diameter (American Orthodontics) and polycarbonate bracket (American Orthodontics), ceramic bracket (American Orthodontics), and metal bracket (3M Unitek) with slots of 0.022x0.030-in were used. The friction coefficient was assessed by means of mechanical traction with the system immersed in artificial saliva. The mean roughness of both wire surface and bracket slots was evaluated by using a surface profilometer. Results The system using TMA wire and polycarbonate bracket had the highest roughness (p<0.05). SS wire with ceramic bracket had the highest friction coefficient, whereas the use of metallic bracket yielded the lowest (p<0.05). However, it was observed a statistically significant difference in the system using TMA wire and ceramic bracket compared to that using TMA wire and polycarbonate bracket (p=0.038). Conclusion Ceramic brackets in association with SS wire should be judiciously used, since this system showed a high friction coefficient. PMID:21437471

FIDALGO, Tatiana Kelly da Silva; PITHON, Matheus Melo; MACIEL, José Vinicius Bolognesi; BOLOGNESE, Ana Maria

2011-01-01

53

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

54

Family of boundary Poisson brackets  

Microsoft Academic Search

We find a new d-parameter family of ultra-local boundary Poisson brackets that satisfy the Jacobi identity. The two already known cases by Soloviev [J. Math. Phys. 34 (1993) 5747, hep-th\\/9305133] and the author [Putting an Edge to the Poisson Bracket, Preprint MIT-CTP-2746, hep-th\\/9806249, J. Math. Phys., to appear] are included in this new continuous family as special cases.

K. Bering

2000-01-01

55

Evaluation of mechanical properties of esthetic brackets.  

PubMed

Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing. PMID:25755677

Matsui, Shigeyuki; Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto

2015-01-01

56

Evaluation of mechanical properties of esthetic brackets  

PubMed Central

Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing. PMID:25755677

Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto

2015-01-01

57

Calculation of four-particle harmonic-oscillator transformation brackets  

NASA Astrophysics Data System (ADS)

A procedure for precise calculation of the three- and four-particle harmonic-oscillator (HO) transformation brackets is presented. The analytical expressions of the four-particle HO transformation brackets are given. The computer code for the calculations of HO transformation brackets proves to be quick, efficient and produces results with small numerical uncertainties. Program summaryProgram title: HOTB Catalogue identifier: AEFQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1247 No. of bytes in distributed program, including test data, etc.: 6659 Distribution format: tar.gz Programming language: FORTRAN 90 Computer: Any computer with FORTRAN 90 compiler Operating system: Windows, Linux, FreeBSD, True64 Unix RAM: 8 MB Classification: 17.17 Nature of problem: Calculation of the three-particle and four-particle harmonic-oscillator transformation brackets. Solution method: The method is based on compact expressions of the three-particle harmonics oscillator brackets, presented in [1] and expressions of the four-particle harmonics oscillator brackets, presented in this paper. Restrictions: The three- and four-particle harmonic-oscillator transformation brackets up to the e=28. Unusual features: Possibility of calculating the four-particle harmonic-oscillator transformation brackets. Running time: Less than one second for the single harmonic-oscillator transformation bracket. References:G.P. Kamuntavi?ius, R.K. Kalinauskas, B.R. Barret, S. Mickevi?ius, D. Germanas, Nuclear Physics A 695 (2001) 191.

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

2010-02-01

58

[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

59

Building a Bracketed Corpus Using ? 2 Statistics  

Microsoft Academic Search

Research based on treebanks is ongoing for many natural language applications. However, the work involved in building a large-scale treebank is laborious and time-consuming. Thus, speeding up the process of building a treebank has become an important task. This paper proposes two versions of probabilistic chunkers to aid the development of a bracketed corpus. The basic version partitions part-of-speech sequences

Yue-Shi Lee; Hsin-Hsi Chen

60

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

61

Corrosion behavior of self-ligating and conventional metal brackets  

PubMed Central

Objective To test the null hypothesis that the aging process in self-ligating brackets is not higher than in conventional brackets. Methods Twenty-five conventional (GN-3M/Unitek; GE-GAC; VE-Aditek) and 25 self-ligating (SCs-3M/Unitek; INs-GAC; ECs-Aditek) metal brackets from three manufacturers (n = 150) were submitted to aging process in 0.9% NaCl solution at a constant temperature of 37 ± 1ºC for 21 days. The content of nickel, chromium and iron ions in the solution collected at intervals of 7, 14 and 21 days was quantified by atomic absorption spectrophotometry. After the aging process, the brackets were analyzed by scanning electron microscopy (SEM) under 22X and 1,000X magnifications. Results Comparison of metal release in self-ligating and conventional brackets from the same manufacturer proved that the SCs group released more nickel (p < 0.05) than the GN group after 7 and 14 days, but less chromium (p < 0.05) after 14 days and less iron (p < 0.05) at the three experimental time intervals. The INs group released less iron (p < 0.05) than the GE group after 7 days and less nickel, chromium and iron (p < 0.05) after 14 and 21 days. The ECs group released more nickel, chromium and iron (p < 0.05) than the VE group after 14 days, but released less nickel and chromium (p < 0.05) after 7 days and less chromium and iron (p < 0.05) after 21 days. The SEM analysis revealed alterations on surface topography of conventional and self-ligating brackets. Conclusions The aging process in self-ligating brackets was not greater than in conventional brackets from the same manufacturer. The null hypothesis was accepted. PMID:24945521

Maia, Lúcio Henrique Esmeraldo Gurgel; Lopes Filho, Hibernon; Ruellas, Antônio Carlos de Oliveira; Araújo, Mônica Tirre de Souza; Vaitsman, Delmo Santiago

2014-01-01

62

In vitro tooth cleaning efficacy of manual toothbrushes around brackets.  

PubMed

The purpose of this laboratory study was to assess the potential cleaning efficacy of nine different toothbrushes around brackets in vitro. Standard and Mini Diamond brackets were fixed on coloured teeth in a special model, coated with white titanium oxide, brushed in a machine with different manual toothbrushes (three different types: planar, staged, and v-shaped bristle field), and tested with a horizontal motion for 1 minute. After brushing, the teeth were scanned and the black surfaces were planimetrically assessed using a grey scale. Tooth areas which were black again after brushing indicated tooth surface contact of the filaments. The remaining white tooth areas around the brackets indicated 'plaque-retentive' niches. Statistical analysis was carried out using the Kruskal-Wallis one-way test of variance for individual comparison. Bonferroni adjustment was used for multiple testing, and comparison of bracket size with Wilcoxon signed rank test. In the most critical area of 2 mm around the brackets, there was no statistically significant difference between the different toothbrushes evaluated. The untouched area ranged from 11 to 26 per cent of the initially whitened tooth surface. By pooling the toothbrushes according to their design, the median cleaning efficacy of the v-shaped (73.1 per cent) and staged (75.6 per cent) toothbrushes resulted in significantly superior cleaning efficacy than planar toothbrushes (60.7 per cent) for standard brackets. For mini bracket type, staged toothbrushes showed a significantly better mean cleaning efficacy (77.8 per cent) than planar (65 per cent) and v-shaped (72.4 per cent) toothbrushes. Staged and v-shaped brush designs resulted in superior cleaning efficacy of teeth with fixed orthodontic attachments than toothbrushes with a planar bristle field. None of the tested toothbrushes showed a consistent, significantly higher cleaning efficacy than the others in this in vitro experiment. PMID:19054810

Schätzle, Marc; Imfeld, Thomas; Sener, Beatrice; Schmidlin, Patrick R

2009-02-01

63

The effects of a newly designed twin-slot bracket on severely malpositioned teeth — a typodont experimental study  

Microsoft Academic Search

SUMMARY The aims of this study were to design a twin-slot bracket featuring two horizontal slots and to examine its effi ciency in tooth displacement. Based on the structure of a traditional edgewise bracket, an additional slot was added to a twin-slot bracket and the prototype products were fabricated for the typodont experiments. The orthodontic correction of malpositioned canines was

Gang Shen; Rong-Jing Chen; Zheng Hu; Yu-Fen Qian

64

Composite attachment: the Trek bottom bracket  

E-print Network

Bottom bracket failures have been one of the most common failures in the composite bicycle frames produced by the Trek Bicycle Corporation. The bottom bracket is the portion of the frame that supports the crank and pedals. An aluminum insert...

Mallard, David

2013-02-22

65

Effects of oil-based and oil-free enamel prophylactic agents on bracket failure--a prospective randomized clinical trial.  

PubMed

This study evaluates and compares the effects of enamel prophylaxis using either oil-free pumice or oil-containing prophylaxis paste on the incidence of bracket failure in orthodontic patients. Forty-six orthodontic patients participated in this prospective clinical trial. A cross-mouth method was used in each patient, in which two diagonal quadrants (i.e. upper right and lower left or vice versa) were randomly assigned to the pumice group and the contralateral diagonal quadrants to the Prophy Paste group. A total of 836 teeth were bonded using Transbond XT (3M Unitek) and monitored for an average of 23 months for bond failure. Chi-square analysis was used to compare the number of bracket failures between the groups. Overall, 26 bond failures occurred by the end of the trial. Fifteen bracket failures were observed in the Prophy Paste group (3.6%) and 11 in the pumice group (2.6%). The failure rates were fairly evenly distributed between the upper and lower jaws. There were no statistically significant differences between the groups (P = 0.43). This study showed that enamel prophylaxis using either pumice or Prophy Paste before orthodontic bonding works equally well in a clinical setting. PMID:25102719

Magnius, Magdalena; Bazargani, Farhan

2014-01-01

66

Branes, strings, and odd quantum Nambu brackets.  

SciTech Connect

The dynamics of topological open branes is controlled by Nambu Brackets. Thus, they might be quantized through the consistent quantization of the underlying Nambu brackets, including odd ones: these are reachable systematically from even brackets, whose more tractable properties have been detailed before.

Curtright, T. L.; Zachos, C. K.; High Energy Physics; Univ. Miami

2004-10-01

67

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. PMID:23408742

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

2013-01-01

68

Effect of delayed polymerization time and bracket manipulation on orthodontic bracket bonding  

NASA Astrophysics Data System (ADS)

This study examined the effect of bracket manipulation in combination with delayed polymerization times on orthodontic bracket shear bond strength and degree of resin composite conversion. Orthodontics brackets were bonded to extracted third molars in a simulated oral environment after a set period of delayed polymerization time and bracket manipulation. After curing the bracket adhesive, each bracket underwent shear bond strength testing followed by micro-Raman spectroscopy analysis to measure the degree of conversion of the resin composite. Results demonstrated the shear bond strength and the degree of conversion of ceramic brackets did not vary over time. However, with stainless steel brackets there was a significant effect (p ? 0.05) of delay time on shear bond strength between the 0.5 min and 10 min bracket groups. In addition, stainless steel brackets showed significant differences related to degree of conversion over time between the 0.5 min and 5 min groups, in addition to the 0.5 min and 10 min groups. This investigation suggests that delaying bracket adhesive polymerization up to a period of 10 min then adjusting the orthodontic bracket may increase both shear bond strength and degree of conversion of stainless steel brackets while having no effect on ceramic brackets.

Ponikvar, Michael J.

69

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. PMID:25025560

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

2014-01-01

70

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. PMID:23372594

Alavi, Shiva; Farahi, Ali

2011-01-01

71

Thermal debracketing of single crystal sapphire brackets.  

PubMed

Because of their optical clarity, single crystal sapphire brackets provide an esthetic advantage over many other types of orthodontic brackets. However, debonding of these brackets has caused iatrogenic damage to enamel. Thermal debonding has been proposed for use in removing sapphire brackets without causing damage to teeth. This study determined the temperature required at the enamel/resin interface to thermally debond sapphire brackets from etched bovine enamel using 23 different commercially available orthodontic resins and one experimental product. The results indicate a wide range of debonding temperatures for the various resins. As a group, the powder-liquid materials had a statistically lower debonding temperature than the two-paste, the no-mix products, or the light-cured materials, for which the temperatures were all similar. This paper presents relative information a clinician can use in selecting an orthodontic bonding resin to minimize thermal damage to the teeth while debonding sapphire brackets. PMID:1554162

Rueggeberg, F A; Lockwood, P E

1992-01-01

72

Ectopic canine control with conventional brackets.  

PubMed

Although evident advances have certainly been made, not only in the use of brackets, but also in the mechanics and type of wires and accessories employed, the most recent systematic review of the literature on this topic stated despite claims regarding the clinical superiority of self-ligating brackets, evidence is generally lacking. Thus, the aim of this study was to show, by means of four clinical case reports, that conventional brackets, used in conjunction with relatively recently introduced thermal nickel-titanium archwires of reduced diameter and extremely light nickel-titanium springs, give results comparable with those achieved via the use of self-ligating brackets. PMID:23158435

Lombardo, Luca

2012-12-01

73

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 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...

2012-04-01

74

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 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...

2014-04-01

75

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

76

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 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...

2011-04-01

77

21 CFR 872.5470 - Orthodontic plastic bracket.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 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...

2010-04-01

78

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. PMID:20616392

Bürger, Kai; Krüger, Jens; Westermann, Rüdiger

2011-01-01

79

Sample-based surface coloring.  

PubMed

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. PMID:20616392

Bürger, Kai; Krüger, Jens; Westermann, Rüdiger

2010-01-01

80

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

81

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. PMID:23762825

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

2013-01-01

82

In vitro tooth cleaning efficacy of electric toothbrushes around brackets.  

PubMed

This in vitro study assessed the cleaning efficacy of different electric toothbrushes around upper incisor brackets. Standard and Mini Diamond brackets were fixed on black-stained teeth. The teeth were coated with white titanium oxide and brushed in a machine twice for 1 minute each. Twelve different brush heads with either a wiping or an oscillating-rotating action were tested. After brushing, the teeth were scanned, the black surfaces were assessed planimetrically and a modified plaque index for orthodontic patients (PIOP) was introduced. Tooth areas, which were black again after brushing indicated tooth surface contact of the filaments and were expressed as a percentage of total area. The remaining white areas around the brackets indicated 'plaque-retentive' niches. Analysis of variance was used for individual comparison of the brush types. Bonferroni/Dunn adjustment was applied for multiple testing. The Sonicare toothbrush handle with the brush head 'Compact ProResults' (81.7 per cent) and the brush head 'Standard ProResults' (80.8 per cent), as well as the sonic Waterpik toothbrush SR 800E with the standard brush head (78.2 per cent), showed statistically significantly better cleaning efficacy than all others. The poorest cleaning efficacy was observed for the oscillating-rotating Braun Oral-B Professional Care with the brush head 'Ortho' (less than 50 per cent). The planimetric findings were in correspondence with the results of the PIOP assessment. Cleaning efficacy of electric toothbrushes around brackets on upper incisors was different between the tested brushes. The PIOP was practicable, effective, and easy to use, although it has to be verified in a clinical study. PMID:20551084

Schätzle, Marc; Sener, Beatrice; Schmidlin, Patrick R; Imfeld, Thomas; Attin, Thomas

2010-10-01

83

Covariant Poisson Brackets in Geometric Field Theory  

NASA Astrophysics Data System (ADS)

We establish a link between the multisymplectic and the covariant phase space approach to geometric field theory by showing how to derive the symplectic form on the latter, as introduced by Crnkovi?-Witten and Zuckerman, from the multisymplectic form. The main result is that the Poisson bracket associated with this symplectic structure, according to the standard rules, is precisely the covariant bracket due to Peierls and DeWitt.

Forger, Michael; Romero, Sandro Vieira

2005-06-01

84

Deformation of metal brackets: a comparative study.  

PubMed

The purpose of this study was to determine the effect of material and design on the force and stress required to permanently deform metal brackets. Fourteen types of metal brackets were categorized according to raw material composition, slot torque degree, and wing type. Five types of raw materials, three types of slot torque degree, and four types of wing design were tested using an archwire torque test developed by Flores. An analysis of variance (ANOVA) and t-test showed that all three categories had a significant effect on the force and stress needed to permanently deform metal brackets. Of the three, raw material had the greatest effect on the amount of force. Results showed that 17-4PH and 303S had higher yield strengths and regular twin brackets had higher resistance to deformation. Also, as slot torque degree increased, brackets deformed with less force. Result confirmed that brackets requiring the greatest stress to permanently deform were made of steel with the greatest hardness. PMID:7978523

Flores, D A; Choi, L K; Caruso, J M; Tomlinson, J L; Scott, G E; Jeiroudi, M T

1994-01-01

85

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

86

The effects of recycling on the tensile bond strength of new and clinically used stainless steel orthodontic brackets: an in vitro study.  

PubMed

The tensile bond strength was evaluated for three different types of stainless steel orthodontic bracket/base combinations (both cast and machined integral bases, and a foil-mesh base). The cast base gave a significantly higher initial bond strength than the other two brackets. Following recycling by either chemical or thermal methods, all the bases demonstrated a significant reduction in bond strength. However, thermal recycling produced an unacceptably large reduction in the bond strength of the cast base and this method of reconditioning should be avoided with these brackets. Recycling the brackets an additional four times was found to result in a further reduction in bond strength, but this was not statistically significant. Clinically used brackets demonstrated a slightly lower, though not statistically significant, bond strength compared to unused brackets following one recycling with either the chemical or thermal method. PMID:2192762

Regan, D; van Noort, R; O'Keeffe, C

1990-05-01

87

Direct bonding of orthodontic brackets to porcelain veneer laminates.  

PubMed

The forces required to debond orthodontic attachments from porcelain veneer laminates were studied in vitro. Brackets were bonded to 160 veneered bovine incisor teeth before the determination of the debond force. The independent variables studied were resin type, priming agent, porcelain surface preparation, and debonding time. The average debond forces were compared with those obtained by debonding brackets bonded to natural teeth by means of the acid-etch technique. The bond between the resin and the porcelain surface was found to be satisfactory for direct bonding of orthodontic attachments. Roughening the porcelain surface and using a silane primer required an average debond force comparable to that of the acid-etched enamel bond at 24 hours. However, it increased the risk for porcelain fracture during debonding. Roughened surfaces and surfaces with micro-fractures could be satisfactorily finished and polished with either a series of graded Ceramiste points or a diamond-impregnated polishing wheel followed by a diamond polishing paste. PMID:2973744

Kao, E C; Boltz, K C; Johnston, W M

1988-12-01

88

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. PMID:23229253

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

2013-01-01

89

Process qualification and testing of LENS deposited AY1E0125 D-bottle brackets.  

SciTech Connect

The LENS Qualification team had the goal of performing a process qualification for the Laser Engineered Net Shaping{trademark}(LENS{reg_sign}) process. Process Qualification requires that a part be selected for process demonstration. The AY1E0125 D-Bottle Bracket from the W80-3 was selected for this work. The repeatability of the LENS process was baselined to determine process parameters. Six D-Bottle brackets were deposited using LENS, machined to final dimensions, and tested in comparison to conventionally processed brackets. The tests, taken from ES1E0003, included a mass analysis and structural dynamic testing including free-free and assembly-level modal tests, and Haversine shock tests. The LENS brackets performed with very similar characteristics to the conventionally processed brackets. Based on the results of the testing, it was concluded that the performance of the brackets made them eligible for parallel path testing in subsystem level tests. The testing results and process rigor qualified the LENS process as detailed in EER200638525A.

Atwood, Clinton J.; Smugeresky, John E. (Sandia National Labs, Livermore,CA); Jew, Michael (Sandia National Labs, Livermore,CA); Gill, David Dennis; Scheffel, Simon (Sandia National Labs, Livermore,CA)

2006-11-01

90

Intramural Sports -Team Tennis Bracket Spring 2014  

E-print Network

Intramural Sports - Team Tennis Bracket Spring 2014 Poachers (12) Lambda Chi and Friends Sunday and Friends Tennis Is Sexy Champions Phi Psi Sunday, June 1st 7:00pm Tennis is Sexy (31) Tuesday, May 27th 9:00pm Phi Psi (FF) Our Team's No Djokavic Tuesday, June 3rd Team Top Spin (23) 9:00pm Tennis Sexy (13

Escher, Christine

91

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. PMID:23032212

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

2012-01-01

92

Noncanonical Poisson brackets for elastic and micromorphic solids  

Microsoft Academic Search

This paper investigates the Lagrangian-to-Eulerian transformation approach to the construction of noncanonical Poisson brackets for the conservative part of elastic solids and micromorphic elastic solids. The Dirac delta function links Lagrangian canonical variables and Eulerian state variables, producing noncanonical Poisson brackets from the corresponding canonical brackets. Specifying the Hamiltonian functionals generates the evolution equations for these state variables from the

Kuo-Ching Chen

2007-01-01

93

Optimal enamel conditioning strategy for rebonding orthodontic brackets: a laboratory study  

PubMed Central

Objective: To compare the conventional etching and primer method (CEP) and the self-etching primer method (SEP) in rebonding brackets. Methods: Forty human maxillary second premolars extracted for orthodontic purpose were randomly divided into 4 equal groups. Group 1 and Group 2 were bonded using the CEP method; Group 3 and Group 4 using the SEP method. All the brackets were debonded and 40 new brackets were rebonded with four different protocols after surface cleaning: Group 1: CEP + adhesive; Group 2: CEP without etch step + adhesive; Group 3: SEP + adhesive; Group 4: non-acidic primer + adhesive. Then, the shear bond strength (SBS) of each group was tested and the measurements of adhesive remnant index scores (ARI) and SEM examination were performed. Results: The mean SBSs for Group 1, 2, 3 and 4 were 14.18, 6.57, 11.90, 5.91 MPa, respectively. Statistical differences of the SBS existed between Group 1 and 2 (P < 0.05) and between Group 3 and 4 (P < 0.05). No difference was found between Group 1 and 3, or Group 2 and 4. Conclusion: Omission of the acid-etching step in rebonding orthodontic brackets may be adequate for the clinical requirement. No differences in SBS and ARI of the rebonded brackets were showed between CEP and SEP methods. PMID:25356128

Zhang, Qi-Feng; Yao, Hua; Li, Zhi-Yong; Jin, Li; Wang, Hui-Ming

2014-01-01

94

Influence of lingual bracket position on microbial and periodontal parameters in vivo  

PubMed Central

Objective Lingual orthodontics is becoming more popular in dental practice. The purpose of the present investigation was to compare plaque formation on teeth bonded with the same bracket onto buccal or lingual surface, with non-bonded control teeth, via an in vivo growth experiment over a 30-day period. Material and Methods A randomized controlled trial with split-mouth design was set up enrolling 20 dental students. Within each subject sites with buccal and lingual brackets and control sites were followed. Clinical periodontal parameters (periodontal pocket depth: PPD; bleeding on probing: BOP) were recorded at baseline and on days 1, 7 and 30. Microbiological samples were taken from the brackets and the teeth on days 1, 7 and 30 to detect colony-forming units (CFU). Total CFU, streptococci CFU and anaerobe CFU were measured. Results No significant differences (P>0.05) were found between buccal and lingual brackets in terms of clinical periodontal parameters and microbiological values. Conclusion Bracket position does not have significant impact on bacterial load and on periodontal parameters. PMID:22858704

SFONDRINI, Maria Francesca; DEBIAGGI, Maurizia; ZARA, Francesca; BRERRA, Roberto; COMELLI, Mario; BIANCHI, Marco; POLLONE, Sara Ramella; SCRIBANTE, Andrea

2012-01-01

95

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

96

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

97

Conceptual design for PSP mounting bracket  

SciTech Connect

Protective structural packages (PSP`s or overpacks) used to ship 2 1/2-ton UF{sub 6} product cylinders are bolted to truck trailers. All bolts penetrate two longitudinal rows of wooden planks. Removal and replacement is required at various intervals for maintenance and routine testing. A conceptual design is presented for mounting brackets which would securely attach PSP`s to trailer frames, reduce removal and replacement time, and minimize risk of personnel injury.

Ransom, G.; Stein, R. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

1991-12-31

98

Rankin–Cohen brackets and formal quantization  

Microsoft Academic Search

In this paper, we use the theory of deformation quantization to understand Connes' and Moscovici's results [A. Connes, H. Moscovici, Rankin–Cohen brackets and the Hopf algebra of transverse geometry, Mosc. Math. J. 4 (1) (2004) 111–130, 311]. We use Fedosov's method of deformation quantization of symplectic manifolds to reconstruct Zagier's deformation [D. Zagier, Modular forms and differential operators, in: K.G.

Pierre Bieliavsky; Xiang Tang; Yijun Yao

2007-01-01

99

Global Attitude Representation and its Lie Bracket  

Microsoft Academic Search

Global representation and various properties of the rigid body attitude, i.e., SO(3), are investigated in this paper. The representations, Euler-Lagrange equation, and Hamilton's equation on the second bundle of SO(3) are formally given. For its important role in nonlinear control theory, the global representation of Lie bracket on T ((SO(3))m ?? Rn), a general tangent bundle of the product space

Kuang-Yow Liant; Li-Sheng Wang; Li-Chen Fu

1993-01-01

100

Toothpaste Prevents Debonded Brackets on Erosive Enamel  

PubMed Central

This study evaluated the effect of high fluoride dentifrice on the bond strength of brackets after erosive challenge. Eighty-four enamel specimens were divided into seven groups (n = 12): WN (distilled water/no acid challenge), W3C (distilled water/3 cycles of acid challenge), and W6C (distilled water/6 cycles of acid challenge) were not submitted to dentifrice treatment. Groups RF3C (regular fluoride dentifrice/3 cycles of acid challenge) and RF6C (regular fluoride dentifrice/6 cycles of acid challenge) were treated with dentifrices containing 1450??g F?/g and HF3C (high fluoride dentifrice/3 cycles of acid challenge) and HF6C (high fluoride dentifrice/6 cycles of acid challenge) were with 5000??g F?/g. Acid challenges were performed for seven days. After bond strength test, there was no significant difference among groups submitted to 3 cycles of acid challenge (P > 0.05). Statistically significant difference was found between the regular and high fluoride dentifrices after 6 cycles of acid challenge (<0.05). Similar areas of adhesive remaining were found among control groups and among groups W6C, RF3C, RF6C, HF3C, and HF6C. The high fluoride dentifrice was able to prevent the reduction of bond strength values of brackets submitted to acid challenge. Clinical relevance: the high fluoride toothpaste prevents debonded brackets on erosive enamel. PMID:25879058

Barros, Érico Luiz Damasceno; Pinto, Shelon Cristina Souza; Borges, Alvaro Henrique; Tonetto, Mateus Rodrigues; Ellwood, Roger Phillip; Pretty, Ian; Bandéca, Matheus Coelho

2015-01-01

101

CO2 laser debonding of a ceramic bracket bonded with orthodontic adhesive containing thermal expansion microcapsules.  

PubMed

We have been studying an easy bracket debonding method using heating of an orthodontic adhesive containing thermal expansion microcapsules. However, heating with a high-temperature heater brings obvious risks of burns around the oral cavity. Thus, we examined safer and more effective bracket debonding methods. The purpose of this in vitro study was to examine the reduction in debonding strength and the time taken using a bracket bonded with an orthodontic adhesive containing thermal expansion microcapsules and a CO2 laser as the heating method while maintaining safety. Ceramic brackets were bonded to bovine permanent mandibular incisors using bonding materials containing various microcapsule contents (0, 30, and 40 wt%), and the bond strengths were measured after laser irradiation for 4, 5, and 6 s and compared with nonlaser-treated groups. Subsequently, the temperature in the pulp chamber during laser irradiation was measured. After laser irradiation for 5 or 6 s, the bond strengths of the adhesive containing 40 wt% microcapsules were significantly decreased to ?0.40?-?0.48-fold (4.6-5.5 MPa) compared with the nonlaser groups. The mean temperature rise of the pulp chamber was 4.3 °C with laser irradiation for 6 s, which was less than that required to induce pulp damage. Based on these results, we conclude that the combined use of a CO2 laser and an orthodontic adhesive containing thermal expansion microcapsules can be effective and safe for debonding ceramic brackets with less enamel damage or tooth pain. PMID:24220847

Saito, Ayano; Namura, Yasuhiro; Isokawa, Keitaro; Shimizu, Noriyoshi

2015-02-01

102

Effect of different preventive agents on bracket shear bond strength: in vitro study  

PubMed Central

Background The effects of fluoride and CPP-ACP before bracket bonding on the shear bond strength of orthodontic brackets have been reported with contradicting results. The objective of this in vitro study was to evaluate the effect of different preventive agents namely; casein phosphopeptide-amorphous-calcium-phosphate (CPP-ACP), fluoride-containing-CPP-ACP (CPP-ACPF) and 5% sodium fluoride (5% NaF), on the enamel-bracket shear bond strength (SBS) and to compare their effects when applied before or after acid-etching. Methods Human premolar teeth were randomly divided into seven groups (16 teeth per group) as follows: the control group, where no preventive agent was applied on the enamel and 6 experimental groups. Teeth in groups 1a, 2a, and 3a were treated with CPP-ACP paste, CPP-ACPF paste, and 5% NaF, respectively before acid-etching. Teeth in groups 1b, 2b and 3b were treated using the same preventive agents after acid-etching. The brackets were then bonded and the teeth were thermocycled. The brackets' SBS was measured and the adhesive remnant was assessed using adhesive remnant index (ARI). Analysis of variance (ANOVA) and Tukey test were performed to compare the SBS among different groups. Chi-square test was used to evaluate differences in ARI scores between the groups. Results Enamel surface treatment with CPP-ACPF after acid-etching significantly increased SBS compared to the control and to its application before acid-etching (P?Brackets' SBS significantly increased when fluoride-containing-CPP-ACP was applied after acid-etching. PMID:24678892

2014-01-01

103

SHEAR BOND STRENGTH OF METALLIC BRACKETS: INFLUENCE OF SALIVA CONTAMINATION  

PubMed Central

Objective: To evaluate the influence of saliva contamination on shear bond strength and the bond failure pattern of 3 adhesive systems (Transbond XT, AdheSE and Xeno III) on orthodontic metallic brackets bonded to human enamel. Material and Methods: Seventy-two permanent human molars were cut longitudinally in a mesiodistal direction, producing seventy-two specimens randomly divided into six groups. Each system was tested under 2 different enamel conditions: no contamination and contaminated with saliva. In T, A and X groups, the adhesive systems were applied to the enamel surface in accordance with manufacturer's instructions. In TS, AS and XS groups, saliva was applied to enamel surface followed by adhesive system application. The samples were stored in distilled water at 37°C for 24 h, and then tested for shear bond strength in a universal testing machine (Emic, DL 2000) running at a crosshead speed of 1 mm/min. After bond failure, the enamel surfaces were observed under an optical microscope at 40x magnification. Results: The control and contaminated groups showed no significant difference in shear bond strength for the same adhesive system. However, shear bond strength of T group (17.03±4.91) was significantly higher than that of AS (8.58±1.73) and XS (10.39±4.06) groups (p<0.05). Regarding the bond failure pattern, TS group had significantly higher scores of no adhesive remaining on the tooth in the bonding area than other groups considering the adhesive remnant index (ARI) used to evaluate the amount of adhesive left on the enamel. Conclusion: Saliva contamination showed little influence on the 24-h shear bond strength of orthodontic brackets. PMID:19466249

Retamoso, Luciana Borges; Collares, Fabrício Mezzomo; Ferreira, Eduardo Silveira; Samuel, Susana Maria Werner

2009-01-01

104

A quantum-classical bracket that satisfies the Jacobi identity  

SciTech Connect

A quantum-classical bracket is proposed and is shown to satisfy the Jacobi identity, in contrast to previous definitions that obey this property only up to higher order terms in the Planck constant ({Dirac_h}/2{pi}). The Jacobi identity is required of a true Lie bracket and ensures that the Lie bracket of constants of motion is also a constant of motion. An explicit calculation of the Jacobi identity highlights the difference between the proposed and traditional definitions. A further example illustrates that the proposed bracket generates a more consistent quantum-classical dynamics than the traditional bracket. The traditional quantum-classical dynamics in the Henon-Heiles system diverges due to higher order ({Dirac_h}/2{pi}) terms. The divergence is eliminated with the proposed bracket.

Prezhdo, Oleg V. [Department of Chemistry, University of Washington, Seattle, Washington 98195-1700 (United States)

2006-05-28

105

Bracketing as a skill in conducting unstructured qualitative interviews.  

PubMed

Aim To provide an overview of bracketing as a skill in unstructured qualitative research interviews. Background Researchers affect the qualitative research process. Bracketing in descriptive phenomenology entails researchers setting aside their pre-understanding and acting non-judgementally. In interpretative phenomenology, previous knowledge is used intentionally to create new understanding. Data sources A literature search of bracketing in phenomenology and qualitative research. Review methods This is a methodology paper examining the researchers' impact in creating data in creating data in qualitative research. Discussion Self-knowledge, sensitivity and reflexivity of the researcher enable bracketing. Conclusion Skilled and experienced researchers are needed to use bracketing in unstructured qualitative research interviews. Implications for research/practice Bracketing adds scientific rigour and validity to any qualitative study. PMID:25783146

Sorsa, Minna Anneli; Kiikkala, Irma; Åstedt-Kurki, Päivi

2015-03-01

106

A New Bracket System for Lingual Orthodontic Treatment  

Microsoft Academic Search

Background and Method: This paper presents a new lingual bracket system differing fundamentally both in design and in manufacturing methods from existing appliances. Using state-of-the-art CAD\\/CAM technology, the two normally separate processes of bracket production and bracket positioning are fused into one unit. In this process, the demand for maximum individuality with simultaneously minimized space requirements is put consistently into

Dirk Wiechmann

2002-01-01

107

Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires  

PubMed Central

Objective To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire. Material and Methods Abzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a ligating wire 0.10-in was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa) were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM. Results Steel-tied brackets (16.48 ± 8.31) showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 ) and self-ligating brackets (1.66 ± 1.57) (P < 0.05), which also differed from each other (P < 0.05). As for the type of wire, 0.019 x 0.025-in steel wire (5.67 ± 3.97) showed lower means (P < 0.05) than 0.16-in NiTi wire (8.26 ± 10.92) and 0.016 x 0.021-in NiTi wire (8.51 ± 7.95), which did not differ from each other (P > 0.05). No statistical differences (P > 0.05) were found between zero (7.76 ± 8.46) and five-degree (7.19 ± 7.93) angulations. Conclusions Friction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied PMID:25162575

Leite, Vanessa Vieira; Lopes, Murilo Baena; Gonini Júnior, Alcides; de Almeida, Marcio Rodrigues; Moura, Sandra Kiss; de Almeida, Renato Rodrigues

2014-01-01

108

Effects of adhesion promoters on the shear bond strengths of orthodontic brackets to fluorosed enamel.  

PubMed

The aims of this in vitro study were to evaluate the effect of enamel fluorosis on the shear bond strength (SBS) of orthodontic brackets and to determine whether adhesion promoter, Enhance LC, increases the bond strength of brackets to fluorosed enamel. Forty-five (30 fluorosed and 15 non-fluorosed) non-carious fresh human premolar teeth, extracted for orthodontic reasons and without any caries or visible defects, were used in this study. The fluorosed teeth were selected according to the modified Thylstrup and Fejerskov index, which is based on the clinical changes in fluorosed teeth. In groups 1 (fluorosed teeth) and 3 (control), the brackets were bonded with Light Bond composite resin and cured with a halogen light. In group 2, Enhance LC was applied to fluorosed enamel before bonding. After bonding, the SBS of the brackets was tested with a universal testing machine. One-way analysis of variance and Tukey multiple comparison tests were used to compare the SBS of the groups. Any adhesive remaining after debonding was assessed and scored according to the modified adhesive remnant index. The results showed that while fluorosis significantly reduced the bond strengths of the orthodontic brackets (mean 13.94 +/- 3.24 MPa; P < 0.01), Enhance LC significantly increased bond strength on fluorosed enamel (mean 18.22 +/- 5.97 Mpa; P < 0.05). Groups 1 and 3 had greater bond failures at the composite-bracket interface, whereas group 2 showed bond failure primarily at the enamel-composite interface. PMID:19073952

Adanir, Necdet; Türkkahraman, Hakan; Yalçin Güngör, Ahmet

2009-06-01

109

Corrosion resistance of three orthodontic brackets: a comparative study of three fluoride mouthwashes.  

PubMed

In the present study, three types of orthodontic brackets were investigated: cobalt-chromium (CoCr), iron-chromium-nickel (FeCrNi) and titanium (Ti) based. Their corrosion resistance was compared with that of platinum (Pt), which was chosen as the reference material because of its excellent electrochemical properties. The test solutions were Elmex, Meridol and Acorea fluoride mouthwashes. Fusayama Meyer artificial saliva was used as the reference solution. The corrosion resistance of the different brackets in the three mouthwashes was assessed electrochemically to determine the corrosion potential and corrosion current density, and polarization resistance values were then calculated. A scanning electron microscopic (SEM) study and an analysis of released metal ions confirmed the electrochemical studies. The results showed that the bracket materials could be divided into two groups: Ti and FeCrNi in one, and CoCr, which has properties close to those of Pt, in the other. Similarly, two groups of electrolytes were identified: Elmex and Acorea mouthwashes in one group, and Meridol mouthwash in the second group. The results indicate that because of the risk of corrosion Meridol mouthwash should not be prescribed for patients wearing Ti or FeCrNi-based orthodontic brackets. PMID:16049037

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

2005-12-01

110

Intramural Sports Women's Sand Volleyball Bracket -Summer 2014  

E-print Network

Intramural Sports Women's Sand Volleyball Bracket - Summer 2014 Sike Girls/Double Trouble Some Court 3 Kinky Sets All games will take place on Dixon Sand Courts You will need to bring your OSU ID Men's Sand Volleyball Bracket - Summer 2014 Foreign Tuesday, July 29, 2014 5:00pm Court 1 French Salsa

Escher, Christine

111

RSRM nozzle actuator bracket/lug fracture mechanics qualification test  

NASA Astrophysics Data System (ADS)

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

1993-07-01

112

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

113

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Bracket adhesive resin and tooth conditioner. 872...Prosthetic Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2012-04-01

114

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...Prosthetic Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2013-04-01

115

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...Prosthetic Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2010-04-01

116

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...Prosthetic Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

2011-04-01

117

In vitro evaluation of the frictional forces between brackets and archwire with three passive self-ligating brackets.  

PubMed

The aim of this in vitro study was to evaluate the frictional forces between bracket and archwire that included three passive self-ligating brackets (Damon SL2 SDS). The brackets were individually bonded to a brass mount using a preformed 0.021 x 0.025 inch stainless steel wire jig in order to exclude adverse tipping or torsion. The central bracket was positioned 1 mm higher than the others, in order that the three brackets were vertically unaligned. Thirty-six similar set-ups including in total 108 brackets were investigated using the same wire: copper (nickel-titanium) 0.014 inches. A testing machine was designed and constructed to measure the frictional forces between the wire and the three-bracket set-up. Twelve set-ups were tested to measure kinetic frictional forces between the wire and unaligned passive self-ligating brackets used in the closed position. The frictional properties of two sets of 12 three-bracket set-ups (control) were tested and measured with an open slide and conventional ligation. A stainless steel ligature wire was used in the former, while elastomeric modules were employed in the latter. One-way analysis of variance showed a significant effect of ligation mode on the frictional properties of the three-bracket set-ups (P < 0.001). Post hoc pairwise comparison showed that the frictional forces arising from passive self-ligation were significantly lower (P < 0.01) than those resulting from elastic ligation. The same result was achieved when comparing self-ligation and metallic ligation (P < 0.01). No significant difference was found when comparing elastic and metallic ligation. PMID:19797412

Cordasco, Giancarlo; Farronato, Giampietro; Festa, Felice; Nucera, Riccardo; Parazzoli, Elena; Grossi, Giovanni Battista

2009-12-01

118

Comparative Evaluation of Friction Resistance of Titanium, Stainless Steel, Ceramic and Ceramic with Metal Insert Brackets with Varying Dimensions of Stainless Steel Wire: An In vitro Multi-center Study  

PubMed Central

Background: The orthodontist seeks an archwire–bracket combination that has both good biocompatibility and low friction. Hence, the aim of this multicenter in vitro study was to evaluate and compare the frictional resistance generated between titanium (Ti), stainless steel (SS), ceramic and ceramic with metal insert (CMI) brackets with SS wires of varying dimensions in a specially designed apparatus. Materials and Methods: The material used in this study were Ti, SS, Ceramic and CMI with 0.018? slot manufactured with zero degree tip and ?7° torque premolar brackets (3M, Unitek) and SS wires of varying dimensions (0.016? round, 0.016 × 0.016? square, 0.016 × 0.022? rectangular and 0.017 × 0.025? rectangular) used. The frictional resistance was measured using Instron Universal testing machine (Model no. 4301). The specimen population in each center composed each of 160 brackets and wires. Differences among the all bracket/wire combinations were tested using (one-way) ANOVA, followed by the student Newman Keuls multiple comparisons of means ranking (at P < 0.05) for the determination of differences among the groups. Results: Ti bracket in combination with 0.017 × 0.025? SS rectangular wire produced significant force levels for an optimum orthodontic movement with least frictional resistance. Conclusion: Ti brackets have least resistance and rectangular wires produced significant force. These can be used to avoid hazards of Nickel. SS brackets revealed higher static frictional force values as the wire dimension increased and showed lower static friction than Ti brackets for all wires except the thicker wire. Our study recommends the preclusion of brackets with rough surface texture (Ti brackets) with SS ligature wire for ligating bracket and archwire are better to reduce friction. PMID:25395796

Kumar, B Sunil; Miryala, Suresh; Kumar, K Kiran; Shameem, K; Regalla, Ravindra Reddy

2014-01-01

119

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

120

Nanoparticle Based Surface-Enhanced Raman Spectroscopy  

SciTech Connect

Surface-enhanced Raman scattering is a powerful tool for the investigation of biological samples. Following a brief introduction to Raman and surface-enhanced Raman scattering, several examples of biophotonic applications of SERS are discussed. The concept of nanoparticle based sensors using SERS is introduced and the development of these sensors is discussed.

Talley, C E; Huser, T R; Hollars, C W; Jusinski, L; Laurence, T; Lane, S M

2005-01-03

121

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. PMID:23162591

Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

2012-01-01

122

The bracket-hack package Christopher Roman Nerz  

E-print Network

The bracket-hack package Christopher Roman Nerz June 5, 2014 Abstract This small LATEX-package1 := and =: to be \\coloneqq (..=) and \\eqqcolon (=..), respectively. brackethack@phoenixes.de 1This package is a `dirty-hack

Ould Ahmedou, Mohameden

123

Bracketing in qualitative research: conceptual and practical matters.  

PubMed

Bracketing is presented as two forms of researcher engagement: with data and with evolving findings. The first form is the well-known identification and temporary setting aside of the researcher's assumptions. The second engagement is the hermeneutic revisiting of data and of one's evolving comprehension of it in light of a revised understanding of any aspect of the topic. Both of these processes are ongoing, and they include the careful development of language with which to represent findings. Extensive everyday examples of bracketing and of interviewing are presented. As a form of disclosure in qualitative research, the background from which this article was written is shared. At that point, Husserl's and Heidegger's historical introductions of bracketing are presented briefly, followed by a discussion of reflexivity and hermeneutics. The article closes with warnings of how residual positivism can work against qualitative rigor and with a suggested qualitative research study on bracketing. PMID:20183407

Fischer, Constance T

2009-07-01

124

14. DETAIL VIEW OF THE CANTILEVER & 'S' BRACKETS AND ...  

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

14. DETAIL VIEW OF THE CANTILEVER & 'S' BRACKETS AND THE SOUTH HANDRAIL, PANEL 1, NEAR THE SOUTHEAST ABUTMENT, LOOKING NORTHWEST Harms - Benton Street Bridge, Spanning Iowa River at Benton Street, Iowa City, Johnson County, IA

125

8. Tower detail, showing pedimented windows and brackets; E elevation. ...  

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

8. Tower detail, showing pedimented windows and brackets; E elevation. (Ceronie) - Rock Island Arsenal, Building No. 1, Gillespie Avenue between Terrace Drive & Hedge Lane, Rock Island, Rock Island County, IL

126

Detail of northernmost balconette with delicate scrolled brackets and railing, ...  

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

Detail of northernmost balconette with delicate scrolled brackets and railing, facing southwest. - Marine Barracks, Panama Canal, Barracks Building, 100' North of Thatcher Highway, Balboa, Former Panama Canal Zone, CZ

127

Interior detail of scrolled brackets on post, west side of ...  

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

Interior detail of scrolled brackets on post, west side of first floor by rear entrance; camera facing north. - Mare Island Naval Shipyard, Hospital Headquarters, Johnson Lane, west side at intersection of Johnson Lane & Cossey Street, Vallejo, Solano County, CA

128

Image Based Flow Visualization for Curved Surfaces  

Microsoft Academic Search

A new method for the synthesis of dense, vector-field aligned textures on curved surfaces is presented, called IBFVS. The method is based on Image Based Flow Visualization (IBFV). In IBFV two-dimensional animated textures are produced by defining each frame of a flow animation as a blend between a warped version of the previous image and a number of filtered white

Jarke J. van Wijk

2003-01-01

129

Photoelastic analysis of stress generated by wires when conventional and self-ligating brackets are used: A pilot study  

PubMed Central

OBJECTIVE: By means of a photoelastic model, this study analyzed the stress caused on conventional and self-ligating brackets with expanded arch wires. METHOD: Standard brackets were adhered to artificial teeth and a photoelastic model was prepared using the Interlandi 19/12 diagram as base. Successive activations were made with 0.014-in and 0.018-in rounded cross section Nickel-Titanium wires (NiTi) and 0.019 x 0.025-in rectangular stainless steel wires all of which made on 22/14 Interlandi diagram. The model was observed on a plane polariscope - in a dark field microscope configuration - and photographed at each exchange of wire. Then, they were replaced by self-ligating brackets and the process was repeated. Analysis was qualitative and observed stress location and pattern on both models analyzed. CONCLUSIONS: Results identified greater stress on the region of the apex of premolars in both analyzed models. Upon comparing the stress between models, a greater amount of stress was found in the model with conventional brackets in all of its wires. Therefore, the present pilot study revealed that alignment of wires in self-ligating brackets produced lower stress in periodontal tissues in expansive mechanics. PMID:25715719

Sobral, Guilherme Caiado; Vedovello, Mário; Degan, Viviane Veroni; Santamaria, Milton

2014-01-01

130

Corrosion resistance of three orthodontic brackets: a comparative study of three fl uoride mouthwashes  

Microsoft Academic Search

SUMMARY In the present study, three types of orthodontic brackets were investigated: cobalt- chromium (CoCr), iron-chromium-nickel (FeCrNi) and titanium (Ti) based. Their corrosion resistance was compared with that of platinum (Pt), which was chosen as the reference material because of its excellent electrochemical properties. The test solutions were Elmex®, Meridol® and Acorea® fl uoride mouthwashes. Fusayama Meyer artifi cial saliva

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

131

Development of a Partially Bracketed Corpus with Part-of-Speech Information Only  

Microsoft Academic Search

Resea\\/ch based on a treebank is active for many natural language applications. However, the work to build a large scale treebank is laborious and tedious. This paper proposes a probabilistic chunker to help the development of a partially bracketed corpus. The chunker partitions the part-of-speech sequence into segments called chunks. Rather than using a treebank as our training corpus, a

Hsin-Hsi Chen; Yue-Shi Lee

1995-01-01

132

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

133

Microleakage under orthodontic brackets bonded with different adhesive systems  

PubMed Central

Objective: This in vitro study aimed to compare the microleakage of orthodontic brackets between enamel-adhesive and adhesive-bracket interfaces at the occlusal and gingival margins bonded with different adhesive systems. Materials and Methods: A total of 144 human maxillary premolar teeth extracted for orthodontic reasons was randomly divided into four groups. Each group was then further divided into three sub-groups. Three total-etching bonding systems (Transbond XT, Greengloo and Kurasper F), three one-step self-etching bonding systems (Transbond Plus SEP, Bond Force and Clearfil S3), three two-step self-etching bonding systems (Clearfil SE Bond, Clearfil Protectbond and Clearfil Liner Bond), and three self-adhesive resin cements (Maxcem Elite, Relyx U 100 and Clearfil SA Cement) were used to bond the brackets to the teeth. After bonding, all teeth were sealed with nail varnish and stained with 0.5% basic fuchsine for 24 h. All samples were sectioned and examined under a stereomicroscope to score for microleakage at the adhesive–enamel and adhesive–bracket interfaces from both occlusal and gingival margins. Statistical Analysis Used: Statistical analyses were performed with Kruskal–Wallis and Wilcoxon signed-rank tests. Results: The results indicate no statistically significant differences between the microleakage scores of the adhesives; microleakage was detected in all groups. Comparison of the average values of the microleakage scores in the enamel–adhesive and adhesive–bracket interfaces indicated statistically significant differences (P < 0.05). The amount of the microleakage was higher at the enamel–adhesive interface than at the bracket-adhesive interface. Conclusions: All of the brackets exhibited some amount of microleakage. This result means that microleakage does not depend on the type of adhesive used. PMID:25713494

Alkis, Huseyin; Turkkahraman, Hakan; Adanir, Necdet

2015-01-01

134

Vibration-Based Surface Recognition for Smartphones  

E-print Network

Vibration-Based Surface Recognition for Smartphones Jungchan Cho, Inhwan Hwang, and Songhwai Oh in a smartphone, it is now possible to obtain information about a user and her surround- ings, such as the location of a smartphone and the activity of the smartphone user, and the obtained context information

135

Bonded Bracket Assmebly for Frameless Solar Panels  

SciTech Connect

In February 2011 the US Department of Energy announced their new Sunshot Initiative. The Sunshot goal is to reduce the total cost of solar energy systems by about 75 percent before the end of the decade. The DOE estimated that a total installed cost of $1 per watt for photovoltaic systems would be equivalent to 6���¢/kilowatt hour (kWh) for energy available from the grid. The DOE also estimated that to meet the $1 per watt goal, PV module costs would need to be reduced to $.50 per watt, balance of systems costs would need to be reduced to $.40 per watt, and power electronic costs would need to reach $.10 per watt. To address the BOS balance of systems cost component of the $1 per watt goal, the DOE announced a funding opportunity called (BOS-X) Extreme Balance of System Hardware Cost Reductions. The DOE identified eight areas within the total BOS costs: 1) installation labor, 2) installation materials, 3) installation overhead and profit, 4) tracker, 5) permitting and commissioning, 6) site preparation, 7) land acquisition, 8) sales tax. The BOS-X funding announcement requested applications in four specific topics: Topic 1: Transformational Building Integrated Photovoltaic (BIPV) Modules Topic 2: Roof and Ground Mount Innovations Topic 3: Transformational Photovoltaic System Designs Topic 4: Development of New Wind Load Codes for PV Systems The application submitted by ARaymond Tinnerman reflected the requirements listed in Topic #2, Roof and Ground Mount Innovations. The goal of topic #2 was to develop technologies that would result in the extreme reduction of material and labor costs associated with applications that require physical connections and attachments to roof and ground mount structures. The topics researched in this project included component cost reduction, labor reduction, weight reduction, wiring innovations, and alternative material utilization. The project objectives included: 1) The development of an innovative quick snap bracket assembly that would be bonded to frameless PV modules for commercial rooftop installations. 2) The development of a composite pultruded rail to replace traditional racking materials. 3) In partnership with a roofing company, pilot the certification of a commercial roof to be solar panel compliant, eliminating the need for structural analysis and government oversight resulting in significantly decreased permitting costs. 4) Reduce the sum of all cost impacts in topic #2 from a baseline total of $2.05/watt to $.34/watt.

Murray, Todd

2013-01-30

136

Surface electromyogram signals classification based on bispectrum.  

PubMed

This paper bispectrum is used to classify human arm movements and control a robotic arm based on upper limb's surface electromyogram signals (sEMG). We use bispectrum based on third-order cumulant to parameterize sEMG signals and classify elbow flexion and extension, forearm pronation and supination, and rest states by an artificial neural network (ANN). Finally, a robotic manipulator is controlled based on classification and parameters extracted from the signals. All this process is made in real-time using QNX ® operative system. PMID:21096229

Orosco, Eugenio; Lopez, Natalia; Soria, Carlos; di Sciascio, Fernando

2010-01-01

137

HOTB: High precision parallel code for calculation of four-particle harmonic oscillator transformation brackets  

NASA Astrophysics Data System (ADS)

This new version of the HOTB program for calculation of the three and four particle harmonic oscillator transformation brackets provides some enhancements and corrections to the earlier version (Germanas et al., 2010) [1]. In particular, new version allows calculations of harmonic oscillator transformation brackets be performed in parallel using MPI parallel communication standard. Moreover, higher precision of intermediate calculations using GNU Quadruple Precision and arbitrary precision library FMLib [2] is done. A package of Fortran code is presented. Calculation time of large matrices can be significantly reduced using effective parallel code. Use of Higher Precision methods in intermediate calculations increases the stability of algorithms and extends the validity of used algorithms for larger input values. Catalogue identifier: AEFQ_v4_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEFQ_v4_0.html Program obtainable from: CPC Program Library, Queen’s University of Belfast, N. Ireland Licensing provisions: GNU General Public License, version 3 Number of lines in programs, including test data, etc.: 1711 Number of bytes in distributed programs, including test data, etc.: 11667 Distribution format: tar.gz Program language used: FORTRAN 90 with MPI extensions for parallelism Computer: Any computer with FORTRAN 90 compiler Operating system: Windows, Linux, FreeBSD, True64 Unix Has the code been vectorized of parallelized?: Yes, parallelism using MPI extensions. Number of CPUs used: up to 999 RAM(per CPU core): Depending on allocated binomial and trinomial matrices and use of precision; at least 500 MB Catalogue identifier of previous version: AEFQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 181, Issue 2, (2010) 420-425 Does the new version supersede the previous version? Yes Nature of problem: Calculation of matrices of three-particle harmonic oscillator brackets (3HOB) and four-particle harmonic oscillator brackets (4HOB) in a more effective way, which allows us to calculate matrix of the brackets up to a few hundred times more rapidly and more accurate than in a previous version. Solution method: Using external parallelization libraries and mutable precision we created a pack of numerical codes based on the methods of compact expressions of the three and four-particle harmonics oscillator brackets 3HOB, 4HOB, presented in [3]. Restrictions: For double precision version calculations can be done up to harmonic oscillator (HO) energy quanta e=28. For quadruple precision mantissa is equal to approximately 34 decimal digits, therefore calculations can be done up to HO energy quanta to e=52. Running time: The running time depends on the harmonic oscillator energy quanta, cluster size and the precision of intermediate calculations. More information on Table 1 for 3HOB and Table 2 for 4HOB. Reasons for a new version: The new program version expands the limits of harmonic oscillator energy quanta and gives shorter calculation time. Extend the limits of calculation of HOB First version was able to produce harmonic oscillator transformation brackets for three and four particles if E?HO energy quanta. With this version of our program, if quadruple or arbitrary precision functions are being used, it is possible to calculate three and four particle harmonic oscillator transformation brackets for greater values of energy and momenta, while sustaining tolerable margin of error. Calculation time As the code of previous version of program was redone using parallelism paradigma, it is now possible to reduce the calculation time of transformation matrices significantly, depending on the size of computing cluster, as the dimensions of matrices are growing very rapidly according to the energy and momenta values. subroutinematrix_4HOB_dimensionCalculates the dimension of 4HOB matrix. subroutinematrix_3HOB_dimensionCalculates the dimension of 3HOB matrix, subroutinematrix_3HOBCalculates the global state array which is used in parallel calculation of 3HOB matrix. subroutinematrix_4HOBCalculates the global sta

Stepšys, A.; Mickevicius, S.; Germanas, D.; Kalinauskas, R. K.

2014-11-01

138

Basics of Ternary Algebras and their underlying Nambu Brackets  

NASA Astrophysics Data System (ADS)

Ternary algebras amount to closing systems of antisymmetrized trinomials of operators. The Filippov conditions (FI, which are not identities) for ternary algebras are contrasted to Bremner's identities dictated by associativity of operator products, and thus analogous to Jacobi identities. Maps of the known FI-compliant ternary algebras to underlying classical Nambu brackets are constructed, which then explain this compliance: FI-compliant ternary algebras are essentially classical Nambu brackets in disguise. In some cases involving infinite algebras, we show the classical limit may be obtained by a contraction of the quantal ternary algebra, and then explicitly realized through classical Nambu brackets. We illustrate this classical-contraction method on our Virasoro-Witt ternary algebra paradigm. The content of the talk is in the two references.

Zachos, Cosmas K.

2013-12-01

139

Comparison of the Debonding Characteristics of Conventional and New Debonding Instrument used for Ceramic, Composite and Metallic Brackets – An Invitro Study  

PubMed Central

Background: Debonding procedure is time consuming and damaging to the enamel if performed with improper technique. Various debonding methods include: the conventional methods that use pliers or wrenches, an ultrasonic method, electrothermal devices, air pressure impulse devices, diamond burs to grind the brackets off the tooth surface and lasers. Among all these methods, using debonding pliers is most convenient and effective method but has been reported to cause damage to the teeth. Recently, a New Debonding Instrument designed specifically for ceramic and composite brackets has been introduced. As this is a new instrument, little information is available on efficacy of this instrument. The purpose of this study was to evaluate the debonding characteristics of both “the conventional debonding Pliers” and “the New debonding instrument” when removing ceramic, composite and metallic brackets. Materials and Methods: One Hundred Thirty eight extracted maxillary premolar teeth were collected and divided into two Groups: Group A and Group B (n = 69) respectively. They were further divided into 3 subGroups (n = 23) each according to the types of brackets to be bonded. In subGroups A1 and B1{stainless steel};A2 and B2{ceramic};A3 and B3{composite}adhesive precoated maxillary premolar brackets were used. Among them {ceramic and composite} adhesive pre-coated maxillary premolar brackets were bonded. All the teeth were etched using 37% phosphoric acid for 15 seconds and the brackets were bonded using Transbond XT primer. Brackets were debonded using Conventional Debonding Plier and New Debonding Instrument (Group B). After debonding, the enamel surface of each tooth was examined under stereo microscope (10X magnifications). Amodifiedadhesive remnant index (ARI) was used to quantify the amount of remaining adhesive on each tooth. Results: The observations demonstrate that the results of New Debonding Instrument for debonding of metal, ceramic and composite brackets were statistically significantly different (p = 0.04) and superior from the results of conventional debonding Pliers. Conclusion: The debonding efficiency of New Debonding Instrument is better than the debonding efficiency of Conventional Debonding Pliers for use of metal, ceramic and composite brackets respectively. PMID:25177639

Gill, Vikas; Reddy, Y. N. N.; Sanadhya, Sudhanshu; Aapaliya, Pankaj; Sharma, Nidhi

2014-01-01

140

Structural Analysis of the Redesigned Ice/Frost Ramp Bracket  

NASA Technical Reports Server (NTRS)

This paper describes the interim structural analysis of a redesigned Ice/Frost Ramp bracket for the Space Shuttle External Tank (ET). The proposed redesigned bracket consists of mounts for attachment to the ET wall, supports for the electronic/instrument cables and propellant repressurization lines that run along the ET, an upper plate, a lower plate, and complex bolted connections. The eight nominal bolted connections are considered critical in the summarized structural analysis. Each bolted connection contains a bolt, a nut, four washers, and a non-metallic spacer and block that are designed for thermal insulation. A three-dimensional (3D) finite element model of the bracket is developed using solid 10-node tetrahedral elements. The loading provided by the ET Project is used in the analysis. Because of the complexities associated with accurately modeling the bolted connections in the bracket, the analysis is performed using a global/local analysis procedure. The finite element analysis of the bracket identifies one of the eight bolted connections as having high stress concentrations. A local area of the bracket surrounding this bolted connection is extracted from the global model and used as a local model. Within the local model, the various components of the bolted connection are refined, and contact is introduced along the appropriate interfaces determined by the analysts. The deformations from the global model are applied as boundary conditions to the local model. The results from the global/local analysis show that while the stresses in the bolts are well within yield, the spacers fail due to compression. The primary objective of the interim structural analysis is to show concept viability for static thermal testing. The proposed design concept would undergo continued design optimization to address the identified analytical assumptions and concept shortcomings, assuming successful thermal testing.

Phillips, D. R.; Dawicke, D. S.; Gentz, S. J.; Roberts, P. W.; Raju, I. S.

2007-01-01

141

On Deformations of Multidimensional Poisson Brackets of Hydrodynamic Type  

NASA Astrophysics Data System (ADS)

The theory of Poisson vertex algebras (PVAs) (Barakat et al. in Jpn J Math 4(2):141-252, 2009) is a good framework to treat Hamiltonian partial differential equations. A PVA consists of a pair of a differential algebra and a bilinear operation called the -bracket. We extend the definition to the class of algebras endowed with commuting derivations. We call this structure a multidimensional PVA: it is a suitable setting to study Hamiltonian PDEs with d spatial dimensions. We apply this theory to the study of symmetries and deformations of the Poisson brackets of hydrodynamic type for d = 2.

Casati, Matteo

2015-04-01

142

Evaluation of Surface Fatigue Strength Based on Surface Temperature  

NASA Astrophysics Data System (ADS)

Surface temperature is considered to be an integrated index that is dependent on not only the load and the dimensions at the contact point but also the sliding velocity, rolling velocity, surface roughness, and lubrication conditions. Therefore, the surface durability of rollers and gears can be evaluated more exactly and simply by the use of surface temperature rather than Hertzian stress. In this research, surface temperatures of rollers under different rolling and sliding conditions are measured using a thermocouple. The effects of load P, mean velocity Vm and sliding velocity Vs on surface temperature are clarified. An experimental formula, which expresses the linear relationship between surface temperature and the P0.86Vs1.31Vm-0.83 value, is used to determine surface temperature. By comparing calculated and measured temperature on the tooth surface of a gear, this formula is confirmed to be applicable for gear tooth surface temperature calculation.

Deng, Gang; Nakanishi, Tsutomu

143

Optical resonators based on Bloch surface waves  

NASA Astrophysics Data System (ADS)

A few recent works suggest the possibility of controlling light propagation at the interface of periodic multilayers supporting Bloch surface waves (BSWs), but optical resonators based on BSWs are yet to demonstrate. Here we discuss the feasibility of exploiting guided BSWs in a ring resonator configuration. In particular, we investigate the main issues related to the design of these structures, and we discuss about their limitations in terms of quality factors and dimensions. We believe these results might be useful for the development of a complete BSW-based platform for application ranging from optical sensing to the study of the light-matter interaction in micro and nano structures.

Menotti, Matteo; Liscidini, Marco

2015-03-01

144

Force loss in archwire-guided tooth movement of conventional and self-ligating brackets.  

PubMed

This study aimed to investigate the differences in the force loss during simulated archwire-guided canine retraction between various conventional and self-ligating brackets. Three types of orthodontic brackets have been investigated experimentally using a biomechanical set-up: 1. conventional ligating brackets (Victory Series and Mini-Taurus), 2. self-ligating brackets (SmartClip: passive self-ligating bracket, and Time3 and SPEED: active self-ligating brackets), and 3. a conventional low-friction bracket (Synergy). All brackets had a nominal 0.022? slot size. The brackets were combined with three rectangular 0.019×0.025? archwires: 1. Remanium (stainless steel), 2. Nitinol SE (nickel-titanium alloy, NiTi), and 3. Beta III Titanium (titanium-molybdenum alloy). Stainless steel ligatures were used with the conventional brackets. Archwire-guided tooth movement was simulated over a retraction path of up to 4mm using a superelastic NiTi coil spring (force: 1 N). Force loss was lowest for the Victory Series and SmartClip brackets in combination with the steel guiding archwire (35 and 37.6 per cent, respectively) and highest for the SPEED and Mini-Taurus brackets in combination with the titanium wire (73.7 and 64.4 per cent, respectively). Force loss gradually increased by 10 per cent for each bracket type in combination with the different wires in the following sequence: stainless steel, Nitinol, and beta-titanium. Self-ligating brackets did not show improved performance compared with conventional brackets. There was no consistent pattern of force loss when comparing conventional and self-ligating brackets or passive and active self-ligating brackets. PMID:23382468

Montasser, Mona A; El-Bialy, Tarek; Keilig, Ludger; Reimann, Susanne; Jäger, Andreas; Bourauel, Christoph

2014-02-01

145

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2014 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket...

2014-04-01

146

Surface plasmon resonance based integrable micro spectrometer  

NASA Astrophysics Data System (ADS)

We propose and realize the concept of a surface plasmon resonance based integrable and planar micro spectrometer that is suitable to determine the wavelength of incident light with sub-nanometer resolution over a broad range of frequencies in the infrared, visible, and ultraviolet regime. A dielectric grating structure with an ascending effective refractive index in the direction perpendicular to the periodicity is applied on top of a 20 nm thick gold film. Monochromatic light in normal incidence excites surface plasmons at confined areas on the sample so that the transmission is reduced locally. Depending on the wavelength, this area of low transmission shifts along the grating. The spatial transmission pattern provides information on the wavelength of the incident light.

Ehlermann, Jens; Siebels, Jan; Fohrmann, Simone; Mendach, Stefan

2015-03-01

147

Interior, view of central hall staircase showing bracketed stair, square ...  

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

Interior, view of central hall staircase showing bracketed stair, square balusters and fluted newel post, camera facing southwest - Naval Training Station, Senior Officers' Quarters District, Quarters No. 4, Naval Station Treasure Island, 4 Whiting Way, Yerba Buena Island, San Francisco, San Francisco County, CA

148

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

149

Cocycles, Compatibility, and Poisson Brackets for Complex Fluids  

E-print Network

Cocycles, Compatibility, and Poisson Brackets for Complex Fluids Hern´an Cendra , Jerrold Marsden and Dynamical Systems, California Institute of Technology, Pasadena CA 91125. USA. marsden for instance Marsden and Ratiu [1999] for the relevant basic background material), the quotient space (TQ

Marsden, Jerrold

150

Topology optimization for air suspension bracket integrated shape optimization  

Microsoft Academic Search

This paper was concerned with a new integrated method of topology optimization and shape optimization. The new method was used in this paper to optimize the structure of an air suspension bracket. In this article, Method of Moving Asymptotes was employed to solve the variable density model discrete by finite element method. The compliance and mass were regarded as topology

Zhao Hongwei; Chen Xiaokai; Lin Yi; Zheng Mingjun

2008-01-01

151

Laser Guided Automated Calibrating System for Accurate Bracket Placement  

PubMed Central

Background: The basic premise of preadjusted bracket system is accurate bracket positioning. It is widely recognized that accurate bracket placement is of critical importance in the efficient application of biomechanics and in realizing the full potential of a preadjusted edgewise appliance. Aim: The purpose of this study was to design a calibrating system to accurately detect a point on a plane as well as to determine the accuracy of the Laser Guided Automated Calibrating (LGAC) System. Materials and Methods: To the lowest order of approximation a plane having two parallel lines is used to verify the accuracy of the system. On prescribing the distance of a point from the line, images of the plane are analyzed from controlled angles, calibrated and the point is identified with a laser marker. Results: The image was captured and analyzed using MATLAB ver. 7 software (The MathWorks Inc.). Each pixel in the image corresponded to a distance of 1cm/413 (10 mm/413) = 0.0242 mm (L/P). This implies any variations in distance above 0.024 mm can be measured and acted upon, and sets the highest possible accuracy for this system. Conclusion: A new automated system is introduced having an accuracy of 0.024 mm for accurate bracket placement.

Anitha, A; Kumar, AJ; Mascarenhas, R; Husain, A

2015-01-01

152

Investigations in a Simplified Bracketed Grid Approach to Metrical Structure  

ERIC Educational Resources Information Center

In this dissertation, I examine the fundamental mechanisms and assumptions of the Simplified Bracketed Grid Theory (Idsardi 1992) in two ways: first, by comparing it with Parametric Metrical Theory (Hayes 1995), and second, by implementing it in the analysis of several case studies in stress assignment and syllabification. Throughout these…

Liu, Patrick Pei

2010-01-01

153

Optimization of injection molding process for automobile headlamp brackets  

Microsoft Academic Search

This study discusses the variant of weight in injection molding of automobile headlamp brackets. The purpose of this study expects to use the minimum number of experiment to get the optimum combinations of factor-level for injection molding process. This study utilizes the parameter design of quality engineering to carry on the experiment and data analysis. The effect maps of factors

L. C. Chao

2008-01-01

154

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

155

Measurement and Simulation of Distortion of a Steel Bracket Casting D. Galles and C. Beckermann  

E-print Network

1 Measurement and Simulation of Distortion of a Steel Bracket Casting D. Galles and C a cast steel bracket. Additional measurements of various bracket features are taken after shakeout is needed to improve agreement. 1. Introduction During cooling of a steel casting, thermal strains

Beckermann, Christoph

156

Standing surface acoustic wave based cell coculture.  

PubMed

Precise reconstruction of heterotypic cell-cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell-cell interactions. PMID:25232648

Li, Sixing; Guo, Feng; Chen, Yuchao; Ding, Xiaoyun; Li, Peng; Wang, Lin; Cameron, Craig E; Huang, Tony Jun

2014-10-01

157

Hand gesture recognition based on surface electromyography.  

PubMed

Human hands are the most dexterous of human limbs and hand gestures play an important role in non-verbal communication. Underlying electromyograms associated with hand gestures provide a wealth of information based on which varying hand gestures can be recognized. This paper develops an inter-individual hand gesture recognition model based on Hidden Markov models that receives surface electromyography (sEMG) signals as inputs and predicts a corresponding hand gesture. The developed recognition model is tested with a dataset of 10 various hand gestures performed by 25 subjects in a leave-one-subject-out cross validation and an inter-individual recognition rate of 79% was achieved. The promising recognition rate demonstrates the efficacy of the proposed approach for discriminating between gesture-specific sEMG signals and could inform the design of sEMG-controlled prostheses and assistive devices. PMID:25570917

Samadani, Ali-Akbar; Kulic, Dana

2014-01-01

158

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. PMID:24935482

2014-01-01

159

Market-based control of active surfaces  

NASA Astrophysics Data System (ADS)

This paper describes a market-based approach to controlling a smart matter-based object transport system, in which an array of distributed air jets applies forces to levitate and control the motion of a planar object. In the smart matter regime, the effects of spatial and temporal variation of operating parameters among a multiplicity of sensor, actuators, and controllers make it desirable for a control strategy to exhibit a minimal dependence on system models, and to be able to arbitrate among conflicting goals. A market-based strategy is introduced that aggregates the control requirements of multiple relatively simple local controllers, each of which seeks to optimize the performance of the system within a limited spatial and temporal range. These local controllers act as the market's consumers, and two sets of distributed air jets act as the producers. Experiments are performed comparing the performance of the market-based strategy to a near-optimal model-derived benchmark, as well as to a hand-tuned PD controller. Results indicate that even though the local controllers in the market are not based on a detailed model of the system dynamics, the market is able to effectively approximate the performance of the model-based benchmark. In certain specialized cases, such as tracking a step trajectory, the performance of the market surpasses the performance of the model-based benchmark by balancing the needs of conflicting control goals. A brief overview of the active surface smart matter prototype being developed at Xerox PARC that is the motivation behind this work is also presented.

Berlin, Andrew A.; Hogg, Tad; Jackson, Warren B.

1998-12-01

160

Adherence of Streptococcus mutans and Candida albicans to different bracket materials  

PubMed Central

Objective: To quantify the adherence of Streptococcus mutans and Candida albicans on brackets made of stainless steel, plastic, ceramic, titanium, and gold, and to evaluate the various sites of adherence of these microorganisms with scanning electron microscopy (SEM). Materials and Methods: Brackets made of stainless steel, plastic, ceramic, titanium, and gold were used. The adherence of S. mutans and C. albicans were studied. The brackets were placed in flat-bottomed vials containing basal medium with 20% sucrose added; the flasks were inoculated with each of the microbial suspensions. The samples were incubated at 37°C for 48 h, after which the brackets were removed. The cells adhering to the glass were counted and the brackets were studied with SEM. Results: When evaluated together, the adherence of S. mutans and C. albicans was increased in the ceramic bracket group. When evaluated separately, metallic brackets had increased number of colony-forming units (CFUs) of S. mutans and the use of titanium brackets increased the CFUs of C. albicans. SEM demonstrated that the adherence of S. mutans and C. albicans together varied according to the bracket materials, with ceramic having the greatest and stainless steel having the least adherence. Conclusions: Oral hygiene may be of greater concern with esthetic brackets since this study shows that microbial adhesion is greater with these brackets. PMID:23066254

Rammohan, Shrinivaasan Nambi; Juvvadi, Shubhaker Rao; Gandikota, Chandra Sekhar; Challa, Padmalatha; Manne, Ranjit; Mathur, Anirudh

2012-01-01

161

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

2008-09-01

162

Green-Schwarz mechanism and ?'-deformed Courant brackets  

NASA Astrophysics Data System (ADS)

We establish that the unusual two-form gauge transformations needed in the Green-Schwarz anomaly cancellation mechanism fit naturally into an ?'-deformed generalized geometry. The algebra of gauge transformations is a consistent deformation of the Courant bracket and features a nontrivial modification of the diffeomorphism group. This extension of generalized geometry emerged from a `doubled ?'-geometry', which provides a construction of exactly gauge and T-duality invariant ?' corrections to the effective action.

Hohm, Olaf; Zwiebach, Barton

2015-01-01

163

SHEAR BOND STRENGTH OF METALLIC BRACKETS PHOTO-ACTIVATED WITH LIGHT-EMITTING DIODE (LED) AT DIFFERENT EXPOSURE TIMES  

PubMed Central

The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE) and LED light (Ortholux, 3M Unitek). Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek) was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek) were attached to upper central incisors. The teeth were randomly divided into four groups (n=15). In Group I (Control), halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37°C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron) at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa) were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05). Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets. PMID:19089170

Rêgo, Emanuel Braga; Romano, Fábio Lourenço

2007-01-01

164

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. PMID:24995233

2014-01-01

165

A smart car for the surface shape measurement of large antenna based on laser tracker  

NASA Astrophysics Data System (ADS)

The geometric accuracy of the surface shape of large antenna is an important indicator of antenna’s quality. Currently, high-precision measurement of large antenna surface shape can be performed in two ways: photogrammetry and laser tracker. Photogrammetry is a rapid method, but its accuracy is not enough good. Laser tracker can achieve high precision, but it is very inconvenient to move the reflector (target mirror) on the surface of the antenna by hand during the measurement. So, a smart car is designed to carry the reflector in this paper. The car, controlled by wireless, has a small weight and a strong ability for climbing, and there is a holding bracket gripping the reflector and controlling reflector rise up and drop down on the car. During the measurement of laser tracker, the laser beam between laser tracker and the reflector must not be interrupted, so two high-precision three-dimensional miniature electronic compasses, which can real-time monitor the relative angle between the holding bracket and the laser tracker’s head, are both equipped on the car and the head of laser tracker to achieve automatic alignment between reflector and laser beam. With the aid of the smart car, the measurement of laser tracker has the advantages of high precision and rapidity.

Gu, Yonggang; Hu, Jing; Jin, Yi; Zhai, Chao

2012-09-01

166

Systematic Uncertainties of Glacial Chronologies Based on Surface Exposure Dating  

NASA Astrophysics Data System (ADS)

Surface exposure dating using terrestrial cosmogenic nuclides provides the opportunity to establish glacial chronologies in semi-arid high mountain regions, where the lack of organic material for radiocarbon dating has limited our knowledge about the timing and the causes of glacial advances so far. However, several scaling systems and calculation schemes exist. This can result in significant systematic uncertainties, particularly at high altitudes as e.g. in the Central Andes. We present and discuss previously published exposure ages from Bolivia and Argentina in order to illustrate the extent of the current uncertainties. It is neither possible to unambiguously determine whether the local Last Glacial Maximum (local LGM) in the tropics occurred in-phase with or predated the global LGM, nor can the subsequent Late Glacial stages be dated accurately enough to infer temperature or precipitation changes at millennial-scale timescales. We then also present new results from the Tres Lagunas in the Sierra de Santa Victoria, NW Argentina. There we can compare our glacial exposure age chronology with bracketing radiocarbon ages from lake sediments. The Tres Lagunas may thus serve as a high-altitude calibration site for 10Be dating. Paleoclimatically, we conclude that glacial deposits in NW-Argentina document glacial advances in-phase with the global LGM, but that the prominent moraines there date to the Late Glacial. This coincides with the well-documented intensification and/or southward shift of the tropical circulation and reflects the strong precipitation-sensitivity of glaciers in arid and semi-arid environments.

Ilgner, J.; Zech, R.; Baechtiger, C.; Kubik, P. W.; Veit, H.

2008-12-01

167

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

168

Exploring the mechanisms underlying surface-based stimulus selection  

PubMed Central

Valdes-Sosa et al. (2000) introduced a transparent-motion design that provides evidence of surface-based processing of visual motion. We show that this design suffers from a motion-duration confound that admits an alternative explanation based on neuronal adaptation and competition. We tested this explanation by reversing the relationship between motion duration and which perceptual surface was “cued”. We also examined the role of color duration. Our findings support the surface-based account and, more specifically, demonstrate that this type of surface-based selection involves selective spatial processing at the scale of the texture elements that define the transparent surfaces. PMID:19941882

Stoner, Gene R.; Blanc, Georgina

2009-01-01

169

Comparison of the frictional characteristics of aesthetic orthodontic brackets measured using a modified in vitro technique  

PubMed Central

Objective The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined. Methods Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a 0.017 × 0.025-in wire in the 0.018-in slots and a 0.019 × 0.025-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (? = 0.05) were also used for statistical analyses. Results There were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (µ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (µ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (µ = 0.85). Conclusions Brackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases. PMID:25667915

Arici, Nursel

2015-01-01

170

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

171

Coated Rectangular Composite Archwires: A Comparison Of Self-Ligating And Conventional Bracket Systems During Sliding Mechanics  

NASA Astrophysics Data System (ADS)

The purpose of this study was to analyze the resistance to sliding of coated rectangular fiber reinforced composite archwires using various brackets systems and second-order bracket angulations. Resistance to sliding was investigated for eight bracket systems: six self-ligating brackets (four passive and two passive-active) and two conventional brackets. A rectangular fiber reinforced composite archwire of 0.019 x 0.025-in dimension from BiomersRTM SimpliClear was drawn through a three-bracket model system at ten millimeters per minute for 2.5 millimeters. For each bracket, the resistance to sliding was measured at four bracket angulations (0°, 2.5°, 5°, and 10°) in a dry state at room temperature. The fiber reinforced composite archwire produced the lowest sliding resistance with the passive self-ligating bracket system (Damon DQ) at each bracket angulation tested. Overall, self-ligating bracket systems generated lower sliding resistance than conventionally ligated systems, and one passive/active self-ligating bracket system (In-Ovation-R). There was a significant increase in resistance to sliding as bracket angulation increased for all bracket systems tested. Microscopic analysis revealed increased perforation of the archwire coating material as bracket angulations were increased. Our findings show that the rectangular fiber reinforced composite archwire may be acceptable for sliding mechanics during the intermediate stages of orthodontic tooth movement, however more long-term studies are needed.

Woods, David Keith

172

Characterisation of surface wettability based on nanoparticles.  

PubMed

Nanoparticles are becoming frequently used in the research area of creating functional surfaces because they can be more versatile than just making dimensions smaller. Particularly, a variety of nanoparticles have been applied for the construction of superhydrophobic and superhydrophilic surfaces with micro- and nano-scaled structures. As nanoparticles can also be fashioned and modified, their effects will be of great importance to the formed surface structures. In the present paper, we review the recent research progress in the utilization of nanoparticles to form extremely wettable/non-wettable surface structures and their influence on surface wettability. This report manifests an apparent inclination of nanoparticle structured surfaces using the multidisciplinary approaches, from the viewpoint of engineer/scientist. Therefore, the typical methodologies with regard to the use of nanoparticles, including the preparation and functionalisation processes, for the realization of surface wettabilities are discussed in this work. The discussions also represent some of the size-determined phenomena that are related to wettable/non-wettable surfaces. This Review thus provides an insight into the connection between nanoparticles and surface wettability. PMID:22392411

Gao, Nan; Yan, Yuying

2012-04-01

173

Comparisons of surface roughnesses and sliding resistances of 6 titanium-based or TMA-type archwires.  

PubMed

Six titanium-based or TMA-type archwires (Beta III, Resolve, CNA, TMA, low-friction ion-implanted TMA or TMAL, and TiMolium) were studied as functions of composition, morphology, surface roughness, and sliding mechanics by using a scanning electron microscope, an x-ray energy dispersive wavelength analyser, a laser specular reflectometer, and a frictional testing machine. In the last instrument, all wires were coupled with 0.022-in stainless steel brackets in which normal forces were applied by 0.010-in stainless steel ligatures. With regard to composition, 5 wires were true beta-titanium alloys having nominal compositions of 80% titanium, 10% molybdenum, 6% zirconium, and 4% tin, and 1 was an alpha-beta alloy having a nominal composition of 90% titanium, 6% aluminum, 3% vanadium, and 1% other. Morphologies varied from surfaces with striations, scale, or layers of drawn material that suggested surface steps or fissures. Specular reflectance and optical roughness measurements divided the archwires into 2 groups of 3: Beta III, Resolve, and CNA had an overall mean value of 0.148 microm; and TMA, TMAL, and TiMolium had a mean overall value of 0.195 microm. These roughness measurements and their accompanying details of the compositional analyses suggested that there could be as few as 2 vendors manufacturing the 5 beta-titanium products. For 6 different values of angulation that embraced the passive and active regions of sliding, the coefficients of friction varied rather narrowly from 0.17 to 0.27 and were independent of surface roughnesses. Although these contemporary products are better than their predecessors of over a decade ago, other issues might be more important than surface finishes or frictional resistances because all products appear fairly comparable. PMID:15520692

Kusy, Robert P; Whitley, John Q; de Araújo Gurgel, Júlio

2004-11-01

174

Poisson commutator-anticommutator brackets for ray tracing and longitudinal imaging via geometric algebra  

E-print Network

We use the vector wedge product in geometric algebra to show that Poisson commutator brackets measure preservation of phase space areas. We also use the vector dot product to define the Poisson anticommutator bracket that measures the preservation of phase space angles. We apply these brackets to the paraxial meridional complex height-angle ray vectors that transform via a 2x2 matrix, and we show that this transformation preserves areas but not angles in phase space. The Poisson brackets here are expressed in terms of the coefficients of the ABCD matrix. We also apply these brackets to the distance-height ray vectors measured from the input and output sides of the optical system. We show that these vectors obey a partial Moebius transformation, and that this transformation preserves neither areas nor angles. The Poisson brackets here are expressed in terms of the transverse and longitudinal magnifications.

Quirino M. Sugon Jr.; Daniel J. McNamara

2008-12-16

175

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. PMID:22924098

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

2012-01-01

176

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

177

Future singularity free accelerating expansion with the modified Poisson brackets  

E-print Network

We show that the second accelerating expansion of the universe appears smoothly from the decelerating universe remarkably after the initial inflation in the two-dimensional soluble semi-classical dilaton gravity along with the modified Poisson brackets of noncommutativity between the relevant fields. However, the ordinary solution coming from the equations of motion following the conventional Poisson algebra describes permanent accelerating universe without any phase change. In this modified model, it turns out that the phase transition is related to the noncommutative Poisson algebra.

Wontae Kim; Edwin J. Son

2007-01-16

178

Theoretical study of an efficient bracketing camera system architecture  

NASA Astrophysics Data System (ADS)

Although High Dynamic Range (HDR) imaging has represented, in the recent years, the topic of important researches, it has not reached yet an excellent level of the HDR scenes acquisition using the available components. Indeed, many solutions have been proposed ranging from bracketing to the beamsplitter but none of these solutions is really consistent with the moving scenes representing light's level difference. In this paper, we present an optical architecture, which exploits the stereoscopic cameras, ensuring the simultaneous capture of four different exposures of the same image on four sensors with efficient use of the available light. We also present a short description of the implemented fusion algorithm implemented.

Besrour, Amine; Snoussi, Hichem; Siala, Mohamed; Abdelkefi, Fatma

2014-03-01

179

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

180

Voxel-based Surface Area Estimation: From Theory to Practice  

E-print Network

Voxel-based Surface Area Estimation: From Theory to Practice G. Windreich N. Kiryati Department of voxels. How can one estimate the (original, continuous) area of a region of interest on the surface, the surface area of a digital voxel world is generally very different than the area of the underlying

Kiryati, Nahum

181

Physics-Based Approaches to Modeling Surface Color Perception  

E-print Network

19 Physics-Based Approaches to Modeling Surface Color Perception Laurence T. Maloney The diversity) Introduction Surface Color Perception. The study of surface color perception is a proper subset of the study of color perception, and one way to highlight the differ- ence between them is to consider the effective

Maloney, Laurence T.

182

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

183

APPLICATION OF HYDROPHILIC STARCH-BASED COATINGS TO POLYETHYLNE SURFACES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Methods for imparting hydrophilic surface properties to hydrophobic plastics are of interest because of their ability to retard the build-up of static electricity, to alter friction and adhesion properties between surfaces, to allow surfaces to be printed with water-based dyes and inks, and to impro...

184

Global mean sea surface based upon SEASAT altimeter data  

NASA Technical Reports Server (NTRS)

A global mean sea surface based upon the SEASAT altimeter data was derived. A combination of crossing arc techniques, accurate SEASAT reference orbits, and a previously computed GOES-3/SEASAT mean sea surface were used in the computation process. This mean sea surface provides a basis for the determination of global ocean circulation patterns and for detailed analysis of the Earth's internal structure. A contour map of the global mean sea surface is presented.

Marsh, J. G.

1984-01-01

185

COMPUTATIONAL VIEW OF SURFACE BASED ORGANIC MASS SPECTROMETRY  

E-print Network

and experimental researchers. # 2008 Wiley Periodicals, Inc., Mass Spec Rev 27:289­315, 2008 Keywords: computerCOMPUTATIONAL VIEW OF SURFACE BASED ORGANIC MASS SPECTROMETRY Barbara J. Garrison1 * and Zbigniew Surface based mass spectrometric approaches fill an important niche in the mass analysis portfolio

Zbigniew, Postawa

186

Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin  

PubMed Central

Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental bleaching under orthodontic bracket. Material and Methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths were used. Staining of tooth blocks with black tea was performed for six days. They were distributed randomly into 4 groups (1-home bleaching with bracket, 2- home bleaching without bracket, 3- office bleaching with bracket, 4 office bleaching without bracket). The color evaluation was performed (CIE L * a * b *) using color reflectance spectrophotometer. Metal brackets were bonded in groups 1 and 3. The groups 1 and 2 samples were subjected to the carbamide peroxide at 15%, 4 hours daily for 21 days. Groups 3 and 4 were subjected to 3 in-office bleaching treatment sessions, hydrogen peroxide 38%. After removal of the brackets, the second color evaluation was performed in tooth block, difference between the area under the bracket and around it, and after 7 days to verified color stability. Data analysis was performed using the paired t-test and two-way variance analysis and Tukey’s. Results: The home bleaching technique proved to be more effective compared to the office bleaching. There was a significant difference between the margin and center color values of the specimens that were subjected to bracket bonding. Conclusions: The bracket bond presence affected the effectiveness of both the home and office bleaching treatments. Key words:Tooth bleaching, spectrophotometry, orthodontics. PMID:25593650

Correr, Americo-Bortolazzo; Rastelli, Alessandra-Nara-Souza; Lima, Débora-Alves-Nunes-Leite; Consani, Rafael-Leonardo-Xediek

2014-01-01

187

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

188

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 Å 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 Å 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

189

Comparision of Shear Bond Strength of Stainless Steel and Ceramic Brackets at 24 Hours after Etching Enamel with Different Proportions of Acidulated Phosphate Fluoride  

PubMed Central

Aims and Objectives: To evaluate and compare the shear bond strength of stainless steel brackets and ceramic brackets at 24h after etching the enamel with acidulated phosphate fluoride gel (1.23% APF) at different proportions (40%,30%,20%) incorporated in conventional etchant (37% phosphoric acid). Materials and Methods: Eighty premolars (maxillary and mandibular first and second premolars) extracted for orthodontic purpose has been selected for the study and samples were divided into 4 groups containing 10 teeth each. Comprised of teeth etched Group 1 with 40% of APF gel etchant is Group 2 teeth etched with 30% of APF gel in Group 3 teeth etched with 20% of APF gel etchant and Group 4 teeth were etched with conventional etchant (37% phosphoric acid). Results: The experimental group of Acidulated Phosphate Fluoride (APF) at different proportion (40%, 30%, 20%) incorporated with etchant application for 40s on the enamel surface at 24h indicated that group 4 showed the higher bond strength of all other remaining groups and the groups 1, 2 and 3 showed satisfactory bond strength. The statistical evaluation also revealed that the bond strength of control group (37% phosphoric acid) was greater than those of experimental groups. Conclusion: The present study results shows that the ceramic brackets have higher bond strength than stainless steel brackets (material wise). PMID:25302260

Abinaya; Karthikeyan; Sarvanan; Vikram, Raj

2014-01-01

190

Surface Plasmon Resonance Immunoassay for Ochratoxin A Based on Nanogold Hollow Balls with Dendritic Surface  

Microsoft Academic Search

A surface plasmon resonance (SPR)?immunosensor based on nano?size gold hollow ball (GHB) with dendritic surface has been developed for detection of Ochratoxin A (OTA). A thionine thin film was initially electropolymerized onto the SPR?probe surface, and then anti?OTA monoclonal antibody (anti?OTA) was immobilized onto the SPR?probe surface by means of GHB conjugation. The binding of target molecules onto the immobilized

2007-01-01

191

Options for a lunar base surface architecture  

NASA Technical Reports Server (NTRS)

The analysis of the Space Exploration Initiative architectures involves making definitions of systems engineering designs for the construction of lunar and Mars bases for the support of science, exploration, and resource production on these planets. This paper discusses the results of the Space Resource Utilization Architecture study, which was initiated to develop the technical capability for extracting useful materials from the indigenous resources of the moon and Mars. For the moon, an infrastructure concept of a base is designed which can support a crew of 12. The major phases of the lunar-base development, the systems and the elements involved, and the physical layout and evolution of the base are described.

Roberts, Barney B.

1991-01-01

192

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

193

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

194

HOW MALLEABLE ARE CHOICE BRACKETS? THE CASE OF MYOPIC LOSS AVERSION  

E-print Network

HOW MALLEABLE ARE CHOICE BRACKETS? THE CASE OF MYOPIC LOSS AVERSION Daniel Hilgers and Matthias Wibral Job Market Paper November 12, 2014 Abstract We study whether a change in the framing of the decision problem affects how individ- uals bracket their choices in the context of myopic loss aversion. We

Franz, Sven Oliver

195

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. PMID:23323244

Kim, Joo Hyoung; Cha, Jung Yul

2012-01-01

196

Elimination of upper bracket resonance in extremely high head Francis hydro-generators  

Microsoft Academic Search

Resonance occurred in the upper bracket of extremely high head Francis hydro-generators due to rotational vibrations. The vibration source was determined from field tests and a finite element analysis (FEA) of the structure. The first order natural frequency of the integrated structure including the upper bracket and the stator frame was then altered using the FEA model. The resonance during

Yongyao Luo; Zhengwei Wang; Guodong Chen; Zujian Lin

2009-01-01

197

Experimental Study of the Uniaxial Automatic Solar Tracking Device Towards Sun Comparison with Fixed Bracket  

Microsoft Academic Search

Experimental study of the uniaxial automatic solar tracking device towards sun comparison with fixed bracket and the two devices to solar radiation quantity of receiving test had been presented. The results showed that the uniaxial automatic tracking device towards sun receive solar radiation quantity than fixed bracket improved 25%-28%.

Xuexian Chen; Wenfeng Gao; Lan Qing; You gang Zhang

2011-01-01

198

Effect of varnishes on surface microhardness of basing materials.  

PubMed

This study investigated the surface microhardness of five basing materials with four varnishes applied to them. Ten Plexiglass molds with 7-mm diameter holes were prepared. Basing materials of Cavitec, Life, Ketac Bond, TimeLine, and Cavalite were placed in the molds to produce 20 samples each. Copalite, Universal, Contact, and Barrier varnishes were applied to the top and bottom surfaces of the base material samples at 1 hour and 24 hours. After air drying, the surface microhardness of the samples was tested with a Micromet II microhardness tester. The surface microhardness of all the basing materials tested was reduced when varnishes were applied to them. Contact and Barrier reduced surface microhardness value more than Copalite and Universal. PMID:1653583

Yang, Y K; Chan, K C

1991-01-01

199

Using a reflective diary to develop bracketing skills during a phenomenological investigation.  

PubMed

In this article, I have attempted to show how a reflective diary can be an effective tool for developing bracketing skills. A framework is necessary to guide reflective thought and encourage deep and critical thinking. My framework was influenced by the work of Schön (1987) and Johns (1984), and related to the concepts of reflecting 'on' and 'in' action, and identified specific learning that had taken place. Bracketing is an important part of the Husserlian approach to descriptive phenomenology. It is a continuous process that can be used in a number of ways. Within my study I used bracketing 'pre', 'in', and 'on' actions. In addition to using bracketing to facilitate the clear emergence of the phenomenon under investigation, it can also be used to help review the methodology of a study. Examples have been given within the article to highlight different situations where bracketing took place. PMID:15227896

Wall, Christine; Glenn, Sheila; Mitchinson, Susan; Poole, Helen

2004-01-01

200

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. PMID:24987734

Sungurtekin Ekçi, Elif; Sandalli, Nuket

2014-01-01

201

PDE-Based Image and Surface Inpainting  

Microsoft Academic Search

Inpainting, the technique of modifying an image in an undetectable form, is as ancient as art itself. The goals and applications of inpainting are numerous, from the restoration of damaged paintings, photographs and films, to the removal of selected undesirable objects. This chapter is intended to present an overview of PDE based image inpainting algorithms, with emphasis in models developed

M. Bertalmío; V. Caselles; G. Haro; G. Sapiro

202

SURFACE PROPERTIES OF SOY-BASED POLYSOAPS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Vegetable oils are obtained from abundantly available and renewable agricultural products. They are also biodegradable and safe to use. These properties make vegetable oils the preferred raw materials over petroleum-based oils for the manufacture of various consumer and industrial products. Veget...

203

Surface characterization of biopolyurethanes based on cellulose derivatives.  

PubMed

Surface tension parameters and surface morphology of biopolyurethanes based on cellulose derivatives thin films, before and after HF cold plasma treatment has been investigated. Calculations are based on the geometric mean approach of Owens and Wendt, Rabel and Kälble, on the Lifshitz-van der Waals acid/base approach of van Oss and co-workers and on the theoretical methods involving quantitative structure-property relationship. For all the investigated samples the polar component contributes significantly to the total surface tensions, as due to the large electron donor interactions. HF cold plasma treatment modifies the surface energy of biopolyurethanes by changing their surface polarity and hydrophilicity. The hydrophilic/hydrophobic balance was studied by means of the free energy of hydration between the biomaterial film and water. The protein adsorption tests of fibrinogen were effected to evaluate the applicability of these biopolyurethanes as biomedical thromboresistant devices. PMID:19020959

Macocinschi, Doina; Filip, Daniela; Butnaru, Maria; Dimitriu, Cristina Daniela

2009-03-01

204

Acceleration of surface-based hybridization reactions using isotachophoretic focusing.  

PubMed

We present a theoretical model and experimental demonstration of a novel method for acceleration of surface-based reactions using isotachophoresis (ITP). We use ITP to focus a sample of interest and deliver a high concentration target to a prefunctionalized surface, thus enabling rapid reaction at the sensor site. The concentration of the focused analyte is bound in space by the ITP interface and, upon reaction with the surface, continues electromigrating downstream, removing any contamination or reacted sample molecules from the surface. This constitutes a one-step react-and-wash assay which can be performed in a simple channel and does not require flow control elements or moving parts. We designed a novel microfluidic chip where reaction surfaces are formed by paramagnetic beads, immobilized at desired sites by an external magnetic field. Using this chip, we compared ITP-based surface hybridization to standard continuous flow-based hybridization and experimentally demonstrated a 2 orders of magnitude improvement in limit of detection (LoD) in a 3 min nucleic acid hybridization assay. The simple analytical model we present allows prediction of the rate of surface reaction under ITP and can be used to design and optimize such assays as a function of the physical properties of the system, including buffer chemistry, applied voltage, analyte mobility, analyte concentration, probe density, and surface length. The method, model, and experimental setup can be applied to various forms or surface reactions and may serve as the basis for highly genetic analysis and immunoassays. PMID:24517175

Karsenty, Merav; Rubin, Shimon; Bercovici, Moran

2014-03-18

205

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

206

Skeleton-Based Seam Computation for Triangulated Surface Parameterization  

E-print Network

Skeleton-Based Seam Computation for Triangulated Surface Parameterization Xu-Ping Zhu1 , Shi-Min Hu Heidelberg 2003 #12;2 Xu-Ping Zhu, Shi-Min Hu, and Ralph Martin high genus, the surface is usually separated

Martin, Ralph R.

207

A geomatics-based road surface temperature prediction model  

Microsoft Academic Search

A GIS-based model for the prediction of road surface temperature is presented that has the ability to explain up to 74% of the spatial variation in road surface temperature in the West Midlands, UK. The approach combines basic spatial data sets with a synergy of surveying techniques to produce a geographical parameter database that drives the spatial component of a

L. Chapman; J. E. Thornes

2006-01-01

208

Face recognition based on depth maps and surface curvature  

Microsoft Academic Search

This paper explores the representation of the human face by features based on the curvature of the face surface. Curature captures many features necessary to accurately describe the face, such as the shape of the forehead, jawline, and cheeks, which are not easily detected from standard intensity images. Moreover, the value of curvature at a point on the surface is

Gaile G. Gordon

1991-01-01

209

TRIANGLE MESH-BASED EDGE DETECTION AND ITS APPLICATION TO SURFACE SEGMENTATION AND ADAPTIVE SURFACE SMOOTHING  

E-print Network

TRIANGLE MESH-BASED EDGE DETECTION AND ITS APPLICATION TO SURFACE SEGMENTATION AND ADAPTIVE SURFACE, Knoxville, TN 37996, USA yiyong@iristown.engr.utk.edu ABSTRACT Triangle meshes are widely used represented by triangle meshes. This paper proposes a robust edge detection algorithm for triangle meshes

Koschan, Andreas

210

Novel spirometry based on optical surface imaging  

PubMed Central

Purpose: To evaluate the feasibility of using optical surface imaging (OSI) to measure the dynamic tidal volume (TV) of the human torso during free breathing. Methods: We performed experiments to measure volume or volume change in geometric and deformable phantoms as well as human subjects using OSI. To assess the accuracy of OSI in volume determination, we performed experiments using five geometric phantoms and two deformable body phantoms and compared the values with those derived from geometric calculations and computed tomography (CT) measurements, respectively. To apply this technique to human subjects, an institutional review board protocol was established and three healthy volunteers were studied. In the human experiment, a high-speed image capture mode of OSI was applied to acquire torso images at 4–5 frames per second, which was synchronized with conventional spirometric measurements at 5 Hz. An in-house matlab program was developed to interactively define the volume of interest (VOI), separate the thorax and abdomen, and automatically calculate the thoracic and abdominal volumes within the VOIs. The torso volume change (TV C = ?Vtorso = ?Vthorax + ?Vabdomen) was automatically calculated using full-exhalation phase as the reference. The volumetric breathing pattern (BPv = ?Vthorax/?Vtorso) quantifying thoracic and abdominal volume variations was also calculated. Under quiet breathing, TVC should equal the tidal volume measured concurrently by a spirometer with a conversion factor (1.08) accounting for internal and external differences of temperature and moisture. Another matlab program was implemented to control the conventional spirometer that was used as the standard. Results: The volumes measured from the OSI imaging of geometric phantoms agreed with the calculated volumes with a discrepancy of 0.0% ± 1.6% (range ?1.9% to 2.5%). In measurements from the deformable torso/thorax phantoms, the volume differences measured using OSI imaging and CT imaging were 1.2% ± 2.1% (range ?0.5% to 3.6%), with a linear regression fitting (slope = 1.02 and R2 = 0.999). In volunteers, the relative error in OSI tidal volume measurement was ?2.2% ± 4.9% (range ?9.2% to 4.8%) and a correlation of r = 0.98 was found with spirometric measurement. The breathing pattern values of the three volunteers were substantially different from each other (BPv = 0.15, 0.45, and 0.32). Conclusions: This study demonstrates the feasibility of using OSI to measure breathing tidal volumes and breathing patterns with adequate accuracy. This is the first time that dynamic breathing tidal volume as well as breathing patterns is measured using optical surface imaging. The OSI-observed movement of the entire torso could serve as a new respiratory surrogate in the treatment room during radiation therapy. PMID:25832058

Li, Guang; Huang, Hailiang; Li, Diana G.; Chen, Qing; Gaebler, Carl P.; Sullivan, James; Zatcky, Joan; Rimner, Andreas; Mechalakos, James

2015-01-01

211

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

2012-06-01

212

In vitro study of color stability of polycrystalline and monocrystalline ceramic brackets  

PubMed Central

Objective The aim of this in vitro study was to analyze color stability of monocrystalline and polycrystalline ceramic brackets after immersion in dye solutions. Methods Seven ceramic brackets of four commercial brands were tested: Two monocrystalline and two polycrystalline. The brackets were immersed in four dye solutions (coffee, red wine, Coke and black tea) and in artificial saliva for the following times: 24 hours, 7, 14 and 21 days, respectively. Color changes were measured by a spectrophotometer. Data were assessed by Multivariate Profile Analysis, Analysis of Variance (ANOVA) and Multiple Comparison Tests of means. Results There was a perceptible change of color in all ceramic brackets immersed in coffee (?E* Allure = 7.61, Inspire Ice = 6.09, Radiance = 6.69, Transcend = 7.44), black tea (?E* Allure = 6.24, Inspire Ice = 5.21, Radiance = 6.51, Transcend = 6.14) and red wine (?E* Allure = 6.49, Inspire Ice = 4.76, Radiance = 5.19, Transcend = 5.64), but no change was noticed in Coke and artificial saliva (?E < 3.7). Conclusion Ceramic brackets undergo color change when exposed to solutions of coffee, black tea and red wine. However, the same crystalline structure, either monocrystalline or polycrystalline, do not follow the same or a similar pattern in color change, varying according to the bracket fabrication, which shows a lack of standardization in the manufacturing process. Coffee dye produced the most marked color changes after 21 days of immersion for most ceramic brackets evaluated. PMID:25279530

de Oliveira, Cibele Braga; Maia, Luiz Guilherme Martins; Santos-Pinto, Ary; Gandini Júnior, Luiz Gonzaga

2014-01-01

213

Opening and closure forces of sliding mechanisms of different self-ligating brackets  

PubMed Central

Self-ligating brackets engage the wire by means of a slide mechanism. Forces that have to be applied to open and close the sliding mechanism of brackets are still unknown. Objective: The aim of this study was to measure and compare the opening and closure forces of different self-ligating brackets. Material and Methods: Three different stainless steel self-ligating brackets (Carriere LX, Ortho Organizers; F1000, Leone; Damon Q, Ormco) were tested. For each different bracket, 20 maxillary right central incisors and 20 mandibular right central incisors were used. Opening and closure forces were measured using an Instron Universal Testing Machine. Statistical analysis was performed and ANOVA and Tukey tests were carried out. Results: Opening forces were registered between 1.1 N and 5.6 N, whereas closure forces were recorded between 1.57 N and 4.87 N. Significant differences were detected among the different brackets and between the two prescriptions tested. Conclusion: The knowledge of different opening and closure forces of self-ligating brackets can help the orthodontist in the clinical management of these devices. PMID:23857652

GANDINI, Paola; ORSI, Linda; SFONDRINI, Maria Francesca; SCRIBANTE, Andrea

2013-01-01

214

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

215

A surface-acoustic-wave-based cantilever bio-sensor.  

PubMed

A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices. PMID:25643594

De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

2015-06-15

216

In vitro assessment of competency for different lingual brackets in sliding mechanics  

PubMed Central

Aim: To determine the static frictional resistance of different lingual brackets at different second order angulations when coupled with stainless steel (SS) archwire in dry and wet conditions. Materials and Methods: Using a modified jig, frictional resistance was evaluated under different conditions for a total of 270 upper premolar lingual brackets (0.018? × 0.025? - conventional - 7th generation and STb, self-ligating – evolution) with no in-built tip or torque together with 0.016? × 0.022? straight length SS archwires. For conventional brackets, the archwire was secured with 0.008? preformed SS short ligature ties. Statistical Analysis: One way analysis of variance with Tukey HSD as post-hoc test was applied for degree wise and bracket wise comparison within dry condition and wet condition. For pair wise comparison Student's t-test was used. Results: Under both conditions the static frictional resistance is significantly higher for self-ligating brackets at 0°, while at 5° and 10° it is higher for 7th generation brackets. Statistically, significant difference does not exist at 0° between conventional brackets and the same was found at 5° and 10° between STb and self-ligating brackets. With an increase in second order angulations, all the evaluated samples exhibited an increased frictional value. Wet condition samples obtained a higher value than their corresponding dry condition. Conclusion: The self-ligating bracket evaluated in this in vitro study is not beneficial in reducing friction during en-mass retraction due to its interactive clip type. PMID:25657988

Lalithapriya, S; Kumaran, N Kurunji; Rajasigamani, K

2015-01-01

217

Comparative assessment of forces generated during simulated alignment with self-ligating and conventional brackets.  

PubMed

The objectives of this study were to comparatively assess the magnitude and direction of forces and moments generated from different bracket systems, during the initial levelling and alignment stage of orthodontic treatment. Three types of brackets were used: Orthos2 (Ormco), Damon2 (Ormco), and In-Ovation R (GAC). The brackets were bonded on resin replicas models of a patient's crowded mandibular arch, and a 0.014 inch Damon archform CuNiTi (Ormco) wire was inserted. The model was mounted on the Orthodontic Measurement and Simulation System (OMSS) and six static measurements were taken at the initial crowded state per bracket for the lateral incisor, canine, and first premolar. A total of 10 repetitions were performed for each measurement, with new brackets and archwires used for each trial. The forces and moments generated were registered directly on the OMSS software and were statistically analyzed using a one-way analysis of variance separately for each dental arch location and force component. Group differences were further analyzed with Tukey's post hoc comparisons test at the 0.05 significance level. The lingually inclined, crowded lateral incisor presented an extrusive and buccal movement and showed the lowest force in the vertical direction, whereas the self-ligating group of brackets generated the highest force in the buccolingual direction. The moments applied by the three bracket systems followed the general trend shown for forces; in the vertical axis, the self-ligating brackets exerted lower forces than their conventional counterpart. This was modified in the buccolingual direction where, in most instances, the self-ligating appliances applied higher moments compared with the conventional bracket. In most cases, the magnitude of forces and moments ranged between 30-70 cN and 2-6 N mm, respectively. However, maximum forces and moments developed at the lateral incisor were almost four times higher than the average. PMID:19349418

Pandis, Nikolaos; Eliades, Theodore; Bourauel, Christoph

2009-12-01

218

Mesogondolella and Jinogondolella (Conodonta): Multielement definition of the taxa that bracket the basal Guadalupian (Middle Permian Series) GSSP  

USGS Publications Warehouse

Multielement definitions are presented here for Mesogondolella and Jinogondolella based on species that bracket the basal Guadalupian (Middle Permian Series) GSSP. Distinctive apparatus characters that appear with the first Jinogondolella include several details of P2 element dimorphism and process bifurcation in S3 elements. The sequential expression of these multielement characters is traced through M. idahoensis, M. lamberti, and J. nankingensis. The resulting multielement definition of Jinogondolella serves to distinguish it from all other closely related genera. Mesogondolella lamberti is recognized as a distinct species, and J. serrata is formally designated a junior synonym of J. nankingensis. ?? 2007 Nanjing Institute of Geology and Palaeontology, CAS.

Lambert, L.L.; Wardlaw, B.R.; Henderson, C.M.

2007-01-01

219

Surface-based Growth Simulation for Opening Flowers Takashi Ijiri  

E-print Network

Surface-based Growth Simulation for Opening Flowers Takashi Ijiri 1 , Mihoshi Yokoo 1 , Saneyuki motivated method for creating animations of opening flowers. We simulate the development of petals based on the observation that flower opening is mainly caused by cell expansion. We use an elastic triangular mesh

Igarashi, Takeo

220

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

221

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

222

Chemical monitors based on Surface-Enhanced Raman Scattering (SERS)  

SciTech Connect

This paper presents an overview of the development of chemical monitors using the Surface-Enhanced Raman Scattering (SERS) technique. The SERS effect is based on recent experimental observations, which have indicated enhancement of the Raman scattering efficiency by factors up to 10[sup 8] when a compound is adsorbed on rough metallic surfaces having submicron protrusions. The focus of our research efforts is on the development of SERS-active sensors and instrumentation capable of field analysis and remote sensing.

Vo-Dinh, T.; Alarie, J.P.; Sutherland, W.S.; Stokes, D.L.; Miller, G.H.

1992-01-01

223

Chemical monitors based on Surface-Enhanced Raman Scattering (SERS)  

SciTech Connect

This paper presents an overview of the development of chemical monitors using the Surface-Enhanced Raman Scattering (SERS) technique. The SERS effect is based on recent experimental observations, which have indicated enhancement of the Raman scattering efficiency by factors up to 10{sup 8} when a compound is adsorbed on rough metallic surfaces having submicron protrusions. The focus of our research efforts is on the development of SERS-active sensors and instrumentation capable of field analysis and remote sensing.

Vo-Dinh, T.; Alarie, J.P.; Sutherland, W.S.; Stokes, D.L.; Miller, G.H.

1992-12-31

224

Triangulation of trimmed surfaces based on constructing triangles  

NASA Astrophysics Data System (ADS)

A new approach for triangulating trimmed surfaces is presented in this paper. The main idea is based on constructing triangles net. The algorithm consists of: (1) reconstruction boundaries of the trimmed surfaces; (2) constructing triangles net; (3) triangulation in narrow polygon zone; (4) accuracy checking and triangle subdivision. In this paper, topological consistency of triangles net is checked in parametric domain. Property of a triangle is appraised in 3D space. Excellent triangles net without cracks can finally be received. The algorithm has been successfully used in surface modeling system SCAD 1.0.

Fan, Jin; Wang, Qifu; Zheng, Xianglin; Zhou, Ji

1996-03-01

225

(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

226

Bonding characteristics of a self-etching primer and precoated brackets: an in vitro study  

Microsoft Academic Search

SUMMARY Little is known about the performance of Transbond™ Plus Self-Etching Primer (TPSEP), especially when used with Adhesive Precoated Brackets™ (APC 1 and APC 2). The aim of this study was to compare the shear bond and rebond strengths and failure sites of APC 1 and APC 2 with a non-coated bracket system (Victory Series (V)) using Transbond XT™ light-cured

Sunil Hirani; Martyn Sherriff

227

Surface activation-based nanobonding and interconnection at room temperature  

NASA Astrophysics Data System (ADS)

Flip chip nanobonding and interconnect system (NBIS) equipment with high precision alignment has been developed based on the surface activated bonding method for high-density interconnection and MEMS packaging. The 3? alignment accuracy in the IR transmission system was approximately ±0.2 µm. The performance of the NBIS has been preliminarily investigated through bonding between relatively rough surfaces of copper through silicon vias (Cu-TSVs) and gold-stud bumps (Au-SBs), and smooth surfaces of silicon wafers. The Cu-TSVs of 55 µm diameter and the Au-SBs of 35 µm diameter with ~6-10 nm surface roughness (RMS) were bonded at room temperature after surface activation using an argon fast atom beam (Ar-FAB) under 0.16 N per bump. Silicon wafers of 50 mm diameter with ~0.2 nm RMS surface roughness were bonded without heating after surface activation. Void-free interfaces both in Cu-TSV/Au-SB and silicon/silicon with bonding strength equivalent to bulk fracture of Au and silicon, respectively, were achieved. A few nm thick amorphous layers were observed across the silicon/silicon interface that was fabricated by the Ar-FAB. This study in the interconnection and bonding facilitates the required three-dimensional integration on the same surface for high-density electronic and biomedical systems.

Howlader, M. M. R.; Yamauchi, A.; Suga, T.

2011-02-01

228

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. PMID:23176080

2012-01-01

229

Nanoparticle-Based Surface Modifications for Microtribology Control and Superhydrophobicity  

NASA Astrophysics Data System (ADS)

The emergence of miniaturization techniques for consumer electronics has brought forth the relatively new and exciting field of microelectromechanical systems (MEMS). However, due to the inherent forces that exist between surfaces at the micro- and nanoscale, scientists and semiconductor manufacturers are still struggling to improve the lifetime and reliability of complex microdevices. Due to the extremely large surface area-to-volume ratio of typical MEMS and microstructured surfaces, dominant interfacial forces exist which can be detrimental to their operational lifetime. In particular, van der Waals, capillary, and electrostatic forces contribute to the permanent adhesion, or stiction , of microfabricated surfaces. This strong adhesion force also contributes to the friction and wear of these silicon-based systems. The scope of this work was to examine the effect of utilizing nanoparticles as the basis for roughening surfaces for the purpose of creating films with anti-adhesive and/or superhydrophobic properties. All of the studies presented in this work are focused around a gas-expanded liquid (GXL) process that promotes the deposition of colloidal gold nanoparticles (AuNPs) into conformal thin films. The GXL particle deposition process is finalized by a critical point drying step which is advantageous to the microelectromechanical systems and semiconductor (IC) industries. In fact, preliminary results illustrated that the GXL particle deposition process can easily be integrated into current MEMS microfabrication processes. Thin films of AuNPs deposited onto the surfaces of silicon-based MEMS and tribology test devices were shown to have a dramatic effect on the adhesion of microstructures. In the various investigations, the apparent work of adhesion between surfaces was reduced by 2-4 orders of magnitude. This effect is greatly attributed to the roughening of the typically smooth silicon oxide surfaces which, in turn, dramatically decreases the "real are of contact" between two contacting surfaces. The studies found that AuNP thin films produced using the lowest initial concentrations of nanoparticles in solution produced estimated real contact areas of around 1%, reducing the adhesion of oxidized Si (100) surfaces from about 37 mJ/m2 down to 0.02 mJ/m 2. In addition, the reducing in real contact area effectively reduced the coefficient of static friction between silicon-based surfaces due to the extremely high dependence of stiction on friction and wear at the microscale. This work also investigated methods of permanently immobilizing AuNP-based films on the silicon surfaces of microstructures in order to create more mechanically robust coatings. The use of organic self-assembled monolayers (SAMs) functionalized with tail-groups known to bond to metallic surfaces were effective in producing much more durable coatings as opposed to non-immobilized AuNP films. Chemical vapor deposition (CVD) techniques were also used to coat rough AuNP films with very thin films of silica (SiO2) to create a robust, rough surface. This method was also very effective in creating a durable coating which is capable of reducing the adhesion energy and friction between two microscale surfaces for extended periods of time. Similar CVD techniques were also used to begin investigating the production of alumina nanoparticle-based superhydrophobic films for use in consumer electronics. Overall, the work presented in this dissertation illustrates that engineered nanoparticle-based surface modifications can be extremely effective in the reduction of the inherent interfacial phenomena that exist on microfabricated systems. This work is can potentially lead us into a new age of the miniaturization of mechanical and electronic devices.

Hurst, Kendall Matthew

2010-11-01

230

Effect of Argon Laser on Enamel Demineralization around Orthodontic Brackets: An In Vitro Study  

PubMed Central

Objective This study was designed to evaluate the effect of argon laser irradiation on development and progress of enamel demineralization around orthodontic brackets. Materials and Methods: Fifty caries-free, intact human premolars were randomly assigned to one of the following five equal groups: Groups 1 (control) and 2: The brackets were bonded using conventional halogen light for 40s and argon laser for 10s, respectively. Teeth in group 3 were lased with argon laser for 10s before bracket bonding with halogen light. Group 4 was the same as group 3 except that brackets were also bonded with argon laser. In group 5 samples were bonded conventionally, immersed in an artificial caries solution for two days and then irradiated for 10s with argon laser. All samples were subjected to demineralization by artificial caries solution for 10 days. After bracket removal, samples were buccolingually sectioned and evaluated by polarized light microscopy. Decalcified lesion depth in each section was measured by a trained examiner in a blind fashion. Data were analyzed in SPSS 14 using one-way ANOVA and Tukey’s HSD post hoc test. Results: The control group showed the greatest mean lesion depth while group 5 revealed the lowest. The laser-treated groups had significantly lower mean lesion depth compared with the control group (P<0.05) except for group 4 (P=0.192). Conclusion: Argon laser irradiation for 10s before or during bracket bonding can increase caries resistance of intact and demineralized enamel. PMID:25584052

Miresmaeili, Amirfarhang; Etrati Khosroshahi, Mohammad; Motahary, Pouya; Rezaei-Soufi, Loghman; Mahjub, Hossein; Dadashi, Maryam; Farhadian, Nasrin

2014-01-01

231

Comparative Evaluation of Shear Bond Strength of Recycled Brackets using Different Methods: An In vitro Study  

PubMed Central

Background: Debonding of brackets commonly occurs during orthodontic treatment. Due to increase in costs replacement of a damaged bracket is not liked by the dentist. This study is done to assess the shear bond strength of recycled brackets using different methods. Materials and Methods: This study was conducted using five groups of orthodontic brackets (0.022” × 0.028”, MBT prescription) bonded on the premolars mounted in cubes. Other materials required were cubical trays, bonding material, light cure unit, universal testing machine, digital camera and sandblasting unit. Results: From the result of ANOVA test we observed the test is significant (F = 20.79, P < 0.01) and the test is rejected. When the Tukey’s t-test result was applied it was seen that the mean shear bond strength of all groups of brackets is as follows: Group I (5.31 Megapascals [Mpa]) < Group II (7.37 Mpa) < Group III (8.96 Mpa) < Group IV (5.56 Mpa) < Control group (9.24 Mpa). Alternatively we can say that shear bond strength of following bracket groups can be arranged as Group I < Group IV < Group II < Group III. Conclusion: From this study we conclude that Group III, which was recycled with an ultrasonic cleaner with electropolisher and silane coupling agent in place of primer, showed the highest shear bond strength. PMID:25395785

Kumar, Mukesh; Maheshwari, Amit; Lall, Rajeev; Navit, Pragati; Singh, Rajeshwar; Navit, S

2014-01-01

232

Comparison of Shear Bond Strength of RMGI and Composite Resin for Orthodontic Bracket Bonding  

PubMed Central

Objective: The aim of this study was to compare the shear bond strength (SBS) of resin modified glass ionomer (RMGI) and composite resin for bonding metal and ceramic brackets. Materials and Methods: Eighty-eight human premolars extracted for orthodontic purposes were divided into 4 groups (n=22). In groups 1 and 2, 22 metal and ceramic brackets were bonded using composite resin (Transbond XT), respectively. Twenty-two metal and ceramic brackets in groups 3 and 4, respectively were bonded using RMGI (Fuji Ortho LC, Japan). After photo polymerization, the teeth were stored in water and thermocycled (500 cycles between 5° and 55°). The SBS value of each sample was determined using a Universal Testing Machine. The amount of residual adhesive remaining on each tooth was evaluated under a stereomicroscope. Statistical analyses were done using two-way ANOVA. Results: RMGI bonded brackets had significantly lower SBS value compared to composite resin bonded groups. No statistically significant difference was observed between metal and ceramic brackets bonded with either the RMGI or composite resin. The comparison of the adhesive remnant index (ARI) scores between the groups indicated that the bracket failure mode was significantly different among groups (P<0.001) with more adhesive remaining on the teeth bonded with composite resin. Conclusion: RMGIs have significantly lower SBS compared to composite resin for orthodontic bonding purposes; however the provided SBS is still within the clinically acceptable range. PMID:25628663

Yassaei, Soghra; Davari, Abdolrahim; Goldani Moghadam, Mahjobeh; Kamaei, Ahmad

2014-01-01

233

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

234

Universal Quantum Transducers based on Surface Acoustic Waves  

E-print Network

We propose a universal, on-chip quantum transducer based on surface acoustic waves in piezo-active materials. Because of the intrinsic piezoelectric (and/or magnetostrictive) properties of the material, our approach provides a universal platform capable of coherently linking a broad array of qubits, including quantum dots, trapped ions, nitrogen-vacancy centers or superconducting qubits. The quantized modes of surface acoustic waves lie in the gigahertz range, can be strongly confined close to the surface in phononic cavities and guided in acoustic waveguides. We show that this type of surface acoustic excitations can be utilized efficiently as a quantum bus, serving as an on-chip, mechanical cavity-QED equivalent of microwave photons and enabling long-range coupling of a wide range of qubits.

Martin J. A. Schuetz; Eric M. Kessler; Geza Giedke; Lieven M. K. Vandersypen; Mikhail D. Lukin; J. Ignacio Cirac

2015-04-20

235

Fundamental normal surfaces and the enumeration of Hilbert bases  

E-print Network

Normal surfaces are a key tool in computational knot theory and 3-manifold topology, and have featured in significant computational breakthroughs in recent years. Despite this, there has been little practical progress on algorithms that use fundamental normal surfaces, which are described in terms of a Hilbert basis for a pointed rational cone on a high-dimensional integer lattice. In this paper we develop and implement several algorithms to enumerate fundamental normal surfaces, by merging domain-specific techniques from normal surface theory with classical Hilbert basis algorithms. The most successful of these combines a maximal admissible face decomposition with the primal Hilbert basis algorithm of Bruns, Ichim and Koch, and in many cases can solve 168-dimensional enumeration problems (based on 24-tetrahedron knot complements) in a matter of hours. As an application, we use this new algorithm to compute 164 previously unknown crosscap numbers in the KnotInfo database of knot invariants.

Burton, Benjamin A

2011-01-01

236

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

237

Multivariate Statistics of Tensor-Based Cortical Surface Morphometry  

E-print Network

. It t d f ti i f ti th J bi Multivariate Tensor-Based Morphometry on Williams Syndrome can capture more confirmed Williams syndrome ·Surfaces were obtained from a prior research (Thompson 2005) Methods. al (2005), `Abnormal cortical compliexity and thickness profiles mapped in Williams syndrome`, J

Wang, Yalin

238

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. PMID:24743157

Liu, Jiansheng; Lu, Yanyan

2014-01-01

239

Topographic Surface-Based Modeling: Building Complex Stratigraphy with Geomorphic Surfaces  

NASA Astrophysics Data System (ADS)

Most three-dimensional geological models built using geostatistical techniques honor well data without difficulty, but fail to achieve geological realism. More often than not, model grids do not capture the stratigraphic complexity present in many depositional settings, and do not follow the actual layering in the sedimentary record, in particular where there are local volumes of steeper dips in channelized environments. Adding to the variety of surface-based modeling techniques that have been developed during the last decade, here we discuss 'topographic surface-based modeling': modeling approaches that build stratigraphy through reproducing the evolution of topographic surfaces over time. The topographies are derived from a variety of sources, including numerical forward modeling, present-day topography and bathymetry, outcrop data, and three-dimensional seismic reflection data. Whenever deposition and erosion occur at the same time, in a spatially predictable pattern (as it is often the case with instability-related morphodynamics, e.g., bedforms, meandering rivers, submarine channels), erosional surfaces are time-transgressive and can have complicated 3D geometries. These complexities are difficult to represent in object-based or voxel-based stochastic models but are easily captured in topographic surface-based models. As locations of deposition, nondeposition, and erosion are recorded for each time step, it is possible to build 3D Wheeler diagrams that show the space-time distribution of preserved and eroded sediment and the time-transgressive nature of erosional surfaces. 3D grids generated this way preserve significant stratigraphic detail without the need for a large number of grid cells. In addition, the topographic surfaces serve as inputs for realistic distribution of properties such as grain size, porosity, and permeability. For example, elevation above channel thalweg can be a proxy for property distribution in channelized settings. The methodology is applicable in modeling different depositional environments, especially in ones dominated by single-thread patterns of deposition and erosion. Examples include sinuous submarine slope channels, submarine lobe deposits, incised river valleys, and tidal inlets. These examples of topographic surface-based models show how the idea of translating geomorphology into stratigraphy has a number of useful applications.

Sylvester, Z.; Cantelli, A.; Howes, N. C.; Jobe, Z. R.; Wolinsky, M. A.; Pirmez, C.; Smith, R.

2012-12-01

240

Bonding bases coated with porous metal powder: a comparison with foil mesh.  

PubMed

This study was undertaken to test the theory that a special porous metal powder coating can provide better mechanical keying than mesh by virtue of its greater surface area and intricate microscopic void network. Identical brackets were laser-welded to an equal number of conventional foil-mesh and powder-coated bases of identical shape and peripheral dimensions. The experimental base material was found to provide significantly greater tensile bond strength at the metal/adhesive interface. PMID:6336902

Hanson, G H; Gibbon, W M; Shimizu, H

1983-01-01

241

Spectrometers for particle measurements in space based on surface reflection  

NASA Astrophysics Data System (ADS)

This is a review talk on space particle spectrometers based on the surface reflection technique. We sum up the experience in development and operation of such instruments accumulated for the last 15 years at the Swedish Institute of space Physics, Kiruna, Sweden in close cooperation with University of Bern, Bern, Switzerland. The technique is relatively new and used in space for measurements of few eV - few keV particles. It was first introduced for neutral atom detection in the GAS instrument onboard the ESA/NASA Ulysses mission (Witte et al., 1992) and later for ion measurements (Barabash et al., 2007) onboard Indian Chandrayaan-1. When a particle hit a surface, secondary electrons release and the particle is either absorbed by the surface or get scattered or reflected. The charge state of the reflected particles normally does not depend on the initial charge state and is neutral but also includes a fraction of negative and positive ions. These charged particles can be analyzed by conventional ion optics. The secondary electrons can be used for triggering a time-of-flight system. The surface reflection technique is close to the usage of foils/ulta-thin foils for particle detections but has a number of advantages. First, it does not require high pre-acceleration potentials and thus allows making more compact and light weight instruments. Secondly, it permits detection of neutral atoms down to 10 eV. Despite the interaction with the surface modifies the original particle velocity, the proper design of the following analyzer section and ion optics can mitigate this effect. We shortly introduce main characteristics of the particle - surface interactions important for this application, describe designs of the instruments flown in space, and show performances of the surface reflection based ENA and ion spectrometers developed for Mars / Venus Express, Chandrayaan-1, BepiColombo, Phobos-Grunt, and Swedish PRISMA.

Barabash, S.; Wieser, M.; Wurz, P.

2012-04-01

242

Prism-coupled surface wave accelerator based on silicon carbide  

NASA Astrophysics Data System (ADS)

A compact, solid-state accelerating structure based on surface waves is proposed and experimentally characterized. The structure, consisting of two SiC layers epitaxially grown on Si slabs and separated from each other by a subwavelength acceleration channel, is shown to support both longitudinal (accelerating) and transverse (deflecting) surface modes. Both modes are experimentally excited and characterized by performing angle-resolved spectroscopy with a wavelength-tunable carbon dioxide laser. Phase velocities of superluminous and subluminous modes are experimentally demonstrated, paving the way for tabletop charged particle acceleration. The same structure can be used for optical characterization of ultrashort electron bunches that generate longitudinal and transverse Cherenkov radiation.

Neuner, Burton, III; Korobkin, Dmitriy; Ferro, Gabriel; Shvets, Gennady

2012-03-01

243

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. PMID:23429517

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

2013-01-01

244

Surface Coverage in Wireless Sensor Networks Based on Delaunay Tetrahedralization  

NASA Astrophysics Data System (ADS)

In this work is presented a new method for sensor deployment on 3D surfaces. The method was structured on different steps. The first one aimed discretizes the relief of interest with Delaunay algorithm. The tetrahedra and relative values (spatial coordinates of each vertex and faces) were input to construction of 3D Voronoi diagram. Each circumcenter was calculated as a candidate position for a sensor node: the corresponding circular coverage area was calculated based on a radius r. The r value can be adjusted to simulate different kinds of sensors. The Dijkstra algorithm and a selection method were applied to eliminate candidate positions with overlapped coverage areas or beyond of surface of interest. Performance evaluations measures were defined using coverage area and communication as criteria. The results were relevant, once the mean coverage rate achieved on three different surfaces were among 91% and 100%.

Ribeiro, M. G.; Neves, L. A.; Pinto, A. R.; Nascimento, M. Z.; Zafalon, G. F. D.; Valêncio, C.

2015-01-01

245

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

246

Development of an integrated capillary valve-based preconcentrator and surface-based immunoassay  

E-print Network

A new generation of integrated preconcentrator and immunoassay was developed. A novel, self-aligned method for patterning Nafion resin was developed and applied to create a preconcentrator. In a parallel effort, a surface-based ...

Liu, Vincent Hok

2009-01-01

247

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. PMID:22666036

Costa, Manuel F. M.

2012-01-01

248

Modeling apple surface temperature dynamics based on weather data.  

PubMed

The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST) dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed) was recorded for seven hours between 11:00-18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of "Fuji" apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management. PMID:25350507

Li, Lei; Peters, Troy; Zhang, Qin; Zhang, Jingjin; Huang, Danfeng

2014-01-01

249

Modeling Apple Surface Temperature Dynamics Based on Weather Data  

PubMed Central

The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST) dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed) was recorded for seven hours between 11:00–18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of “Fuji” apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management. PMID:25350507

Li, Lei; Peters, Troy; Zhang, Qin; Zhang, Jingjin; Huang, Danfeng

2014-01-01

250

Lunar surface roughness based on multiscale morphological method  

NASA Astrophysics Data System (ADS)

Surface roughness is a useful tool to reflect numerous geological characteristics. Lunar Orbiter Laser Altimeter (LOLA) Gridded Data Records (GDRs) are used as the datum. In this paper, Lunar surface roughness maps are built based on morphological methods in image processing. As roughness measure, elevations of GDRs are considered as pixels of an image. Structuring element (SE) is employed as a scale-dependent measure of roughness maps. Global roughness maps with different resolutions are built to interpret the stability of our roughness measure. Global roughness with different-size SEs is mapped based on GDRs with the resolution of 64 pixels per degree to discuss the roughness variations in local regions determined by SEs. Regional roughness maps provide significant melt-related overviews of typical topography.

Cao, Wei; Cai, Zhanchuan; Tang, Zesheng

2015-04-01

251

Standing surface acoustic wave (SSAW)-based cell washing.  

PubMed

Cell/bead washing is an indispensable sample preparation procedure used in various cell studies and analytical processes. In this article, we report a standing surface acoustic wave (SSAW)-based microfluidic device for cell and bead washing in a continuous flow. In our approach, the acoustic radiation force generated in a SSAW field is utilized to actively extract cells or beads from their original medium. A unique configuration of tilted-angle standing surface acoustic wave (taSSAW) is employed in our device, enabling us to wash beads with >98% recovery rate and >97% washing efficiency. We also demonstrate the functionality of our device by preparing high-purity (>97%) white blood cells from lysed blood samples through cell washing. Our SSAW-based cell/bead washing device has the advantages of label-free manipulation, simplicity, high biocompatibility, high recovery rate, and high washing efficiency. It can be useful for many lab-on-a-chip applications. PMID:25372273

Li, Sixing; Ding, Xiaoyun; Mao, Zhangming; Chen, Yuchao; Nama, Nitesh; Guo, Feng; Li, Peng; Wang, Lin; Cameron, Craig E; Huang, Tony Jun

2015-01-01

252

Miniature polarization analyzer based on surface plasmon polaritons  

NASA Astrophysics Data System (ADS)

We investigated a miniature plasmonic polarization analyzer measuring Stokes parameters of a light. The optical component consists of a 2 × 2 polarizer array, three linear polarizers, and one right-handed circular polarizer. These polarizers are formed with bull's eye structures on a metal surface. The measurements of Stokes parameters in a unit radius Poincaré sphere were demonstrated. Compact polarization-dependent optical sensing and imaging can be envisioned based on the miniature polarization analyzer.

Xie, Yu-Bo; Liu, Zheng-Yang; Wang, Qian-Jin; Zhu, Yong-Yuan; Zhang, Xue-Jin

2014-09-01

253

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

254

Palladium nanoparticle-based surface acoustic wave hydrogen sensor.  

PubMed

Palladium (Pd) nanoparticles (5-20 nm) are used as the sensing layer on surface acoustic wave (SAW) devices for detecting H2. The interaction with hydrogen modifies the conductivity of the Pd nanoparticle film, producing measurable changes in acoustic wave propagation, which allows for the detection of this explosive gas. The nanoparticle-based SAW sensor responds rapidly and reversibly at room temperature. PMID:25746067

Sil, Devika; Hines, Jacqueline; Udeoyo, Uduak; Borguet, Eric

2015-03-18

255

Randomized controlled clinical trial of oral health-related quality of life in patients wearing conventional and self-ligating brackets  

PubMed Central

Objective The aim of this randomized controlled clinical trial was to compare oral health-related quality of life (OHRQoL) of patients treated with conventional, active self-ligating (ASL), and passive self-ligating (PSL) brackets in different therapeutic phases. Methods Sixty patients (mean age 18.3 years; 29 males and 31 females) requiring orthodontic treatment were randomly and equally assigned to receive conventional (Victory Series), ASL (In-Ovation R), or PSL (Damon 3MX) brackets. OHRQoL was measured with a self-administered modified 16-item Malaysian version of the Oral Health Impact Profile for immediate (soon after the visit) and late (just before the subsequent visit) assessments of the bonding and activation phases. Data were analyzed with the Kruskal-Wallis and chi-square tests. Results The PSL and ASL groups showed more immediate and late impacts in the bonding phase, respectively; the conventional group was affected in both the assessments. The first activation phase had similar impacts in the groups. After the second activation, the conventional group showed more immediate impacts, whereas the PSL and ASL groups had more late impacts. The commonly affected domains were "physical disability," "functional limitation," "physical pain," and "psychological discomfort." No significant differences in the prevalence and severity of immediate and late impacts on OHRQoL of the patients were noted in any therapeutic phase. Conclusions No bracket system seems to ensure superior OHRQoL. This information could be useful for explaining the therapeutic phases, especially the initial one, and selecting the optimal bracket system based on the patient's preference. PMID:25133131

Mansor, Noorhanizar; Saub, Roslan

2014-01-01

256

Effects of self-ligating and conventional brackets on halitosis and periodontal conditions.  

PubMed

Abstract Objective: To evaluate the effects of fixed orthodontic treatment with steel-ligated conventional brackets and self-ligating brackets on halitosis and periodontal health. Materials and Methods: Sixty patients, at the permanent dentition stage aged 12 to 18 years, who had Angle Class I malocclusion with mild-to-moderate crowding were randomly selected. Inclusion criteria were nonsmokers, without systematic disease, and no use of antibiotics and oral mouth rinses during the 2-month period before the study. The patients were subdivided into three groups randomly: the group treated with conventional brackets (group 1, n ?=? 20) ligated with steel ligature wires, the group treated with self-ligating brackets (group 2, n ?=? 20), and the control group (group 3, n ?=? 20). The periodontal records were obtained 1 week before bonding (T1), immediately before bonding (T2), 1 week after bonding (T3), 4 weeks after bonding (T4), and 8 weeks after bonding (T5). Measurements of the control group were repeated within the same periods. The volatile sulfur components determining halitosis were measured with the Halimeter at T2, T3, T4, and T5. A two-way repeated measures of analysis of variance (ANOVA) was used to compare the groups statistically. Results: No statistically significant group × time interactions were found for plaque index, gingival index, pocket depth, bleeding on probing, and halitosis, which means three independent groups change like each other by time. The risk of tongue coating index (TCI) being 2 was 10.2 times higher at T1 than at T5 (P < .001). Therefore, the probability of higher TCI was decreased by time in all groups. Conclusions: The self-ligating brackets do not have an advantage over conventional brackets with respect to periodontal status and halitosis. PMID:25101909

Kaygisiz, Emine; Uzuner, Fatma Deniz; Yuksel, Sema; Taner, Levent; Culhao?lu, Rana; Sezgin, Yasemin; Ate?, Can

2014-08-01

257

Standing surface acoustic wave (SSAW)-based microfluidic cytometer.  

PubMed

The development of microfluidic chip-based cytometers has become an important area due to their advantages of compact size and low cost. Herein, we demonstrate a sheathless microfluidic cytometer which integrates a standing surface acoustic wave (SSAW)-based microdevice capable of 3D particle/cell focusing with a laser-induced fluorescence (LIF) detection system. Using SSAW, our microfluidic cytometer was able to continuously focus microparticles/cells at the pressure node inside a microchannel. Flow cytometry was successfully demonstrated using this system with a coefficient of variation (CV) of less than 10% at a throughput of ~1000 events s(-1) when calibration beads were used. We also demonstrated that fluorescently labeled human promyelocytic leukemia cells (HL-60) could be effectively focused and detected with our SSAW-based system. This SSAW-based microfluidic cytometer did not require any sheath flows or complex structures, and it allowed for simple operation over a wide range of sample flow rates. Moreover, with the gentle, bio-compatible nature of low-power surface acoustic waves, this technique is expected to be able to preserve the integrity of cells and other bioparticles. PMID:24406848

Chen, Yuchao; Nawaz, Ahmad Ahsan; Zhao, Yanhui; Huang, Po-Hsun; McCoy, J Phillip; Levine, Stewart J; Wang, Lin; Huang, Tony Jun

2014-03-01

258

Estimating illuminant color based on luminance balance of surfaces.  

PubMed

To accomplish color constancy the illuminant color needs to be discounted from the light reflected from surfaces. Some strategies for discounting the illuminant color use statistics of luminance and chromaticity distribution in natural scenes. In this study we showed whether color constancy exploits the potential cue that was provided by the luminance balance of differently colored surfaces. In our experiments we used six colors: bright and dim red, green, and blue, as surrounding stimulus colors. In most cases, bright colors were set to be optimal colors. They were arranged among 60 hexagonal elements in close-packed structure. The center element served as the test stimulus. The observer adjusted the chromaticity of the test stimulus to obtain a perceptually achromatic surface. We used simulated black body radiations of 3000 (or 4000), 6500, and 20000 K as test illuminants. The results showed that the luminance balance of surfaces with no chromaticity shift had clear effects on the observer's achromatic setting, which was consistent with our hypothesis on estimating the scene illuminant based on optimal colors. PMID:22330370

Uchikawa, Keiji; Fukuda, Kazuho; Kitazawa, Yusuke; MacLeod, Donald I A

2012-02-01

259

Low-frequency balancing of two-bracket rotors of turbomachines  

Microsoft Academic Search

A method for balancing high-speed two-bracket turbomachine rotors, widely employed in gas-turbine engines, general-purpose\\u000a air compressors, turbogenerators, and engine turbosupercharging units, is examined. A procedure is proposed for stage-by-stage\\u000a dynamic balancing of turbomachine rotors, including dynamic balancing of impellers on a mandrel. The influence-coefficients\\u000a method has been used to calculate disbalances. Recommendations are offered for applying low-frequency balancing of bracket

S. S. Evgen’ev; R. R. Zalyaev

2007-01-01

260

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.

2012-04-01

261

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

262

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

263

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. PMID:23435208

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

2013-01-01

264

Surface Deformation Mapping Applications using Ground Based Interferometric Radar  

NASA Astrophysics Data System (ADS)

For earth sciences, one application of ground based interferometric radar (GBIR) is surface deformation mapping with sub-millimeter sensitivity. A number of studies found in the open literature have successfully demonstrated the ability to apply GBIR to a variety scenarios including terrain mapping and monitoring of landslide movements. In this study, we explore further the potential of GBIR with variable frequency and full polarimetry capabilities for use in surface deformation mapping. In addition, portability and repeatability issues are addressed such that the system can be removed and re-positioned at the same point with relatively high (geodetic-grade) precision. Phase noise and sensitivity to deformation will be tested using a controlled experiment involving incremental, relative motion of targets. Study results and development progress will be presented. This project is sponsored in part by a grant from the National Science Foundation.

Legarsky, J. J.; Gomez, F. G.; Rosenblad, B.; Loehr, E.

2010-12-01

265

Discrete Surface Modeling Based on Google Earth: A Case Study  

E-print Network

Google Earth (GE) has become a powerful tool for geological, geophysical and geographical modeling; yet GE can be accepted to acquire elevation data of terrain. In this paper, we present a real study case of building the discrete surface model (DSM) at Haut-Barr Castle in France based on the elevation data of terrain points extracted from GE using the COM API. We first locate the position of Haut-Barr Castle and determine the region of the study area, then extract elevation data of terrain at Haut-Barr, and thirdly create a planar triangular mesh that covers the study area and finally generate the desired DSM by calculating the elevation of vertices in the planar mesh via interpolating with Universal Kriging (UK) and Inverse Distance Weighting (IDW). The generated DSM can reflect the features of the ground surface at Haut-Barr well, and can be used for constructingthe Sealed Engineering Geological Model (SEGM) in further step.

Mei, Gang; Xu, Nengxiong

2012-01-01

266

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

267

A new light-cured glass ionomer cement that bonds brackets to teeth without etching in the presence of saliva  

Microsoft Academic Search

Previous studies stress certain advantages of glass ionomer cements, for use in bonding orthodontic brackets to teeth. Failure rate, however, had been higher than with conventional procedures. A new light-cured glass ionomer cement exhibited all the necessary qualities needed to bond brackets, without any etching and in the presence of saliva. The tensile strength of this cement exhibited enough resistance

Elliott Silverman; Morton Cohen; Richard S. Demke; Mitchell Silverman

1995-01-01

268

A comparative experimental investigation of torque capabilities induced by conventional and active, passive self-ligating brackets.  

PubMed

Summary INTRODUCTION : A proper selected bracket-archwire combination displays a determining factor in the efficacy of torque applied to a tooth at the final stages of an orthodontic treatment. The objective of the current study was to assess the torque capabilities of various bracket systems combined with diverse archwire materials and cross-sections. PMID:25414477

Katsikogianni, Eleni N; Reimann, Susanne; Weber, Anna; Karp, Jakob; Bourauel, Christoph

2014-11-19

269

Shear bond strength of metal brackets to feldspathic porcelain treated by Nd:YAG laser and hydrofluoric acid.  

PubMed

Adult orthodontic treatment requires bonding orthodontic attachment to dental restorations. Ceramics are commonly used as esthetic restorative materials for the crowns and bridges. The present study evaluated the shear bond strength of metal orthodontic brackets to the feldspathic porcelain surfaces following conditioning by different powers of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and hydrofluoric acid as a conventional method. Seventy-two glazed porcelain samples were prepared and randomly attributed to six equal groups of 12. In the conventional hydrofluoric (HF) group, the specimens were etched by 9.6% hydrofluoric acid for 4 min. In laser groups, samples were conditioned by 0.75-, 1-, 1.25-, 1.5-, and 2-W Nd:YAG laser for 10 s. Metal brackets were bonded to porcelain samples and after being stored in distilled water for 24 h, they were subjected to thermocycling for 500 cycles. The debonding was carried out by a Zwick testing machine. The data were statistically analyzed by ANOVA and Tamhane multiple comparisons tests. The mean ± SD of the shear bond strength in the laser group 0.75, 1, 1.25, 1.5, and 2 W and HF group was 2.2?±?0.9, 4.2?±?1.1, 4.9?±?2.4, 7?±?1.7, 9.6?±?2.7, and 9.4?±?2.5, respectively. Together with the increased power of laser, the mean shear bond strength was increased continuously and no significant differences were found between the HF group and the laser groups with power of 1.5 or 2 W. Also, there was no significant difference between all test groups in ARI scores. There was no significant difference between bond strength of laser groups with power of 1.5 and 2 W and HF-etched group. So, Nd:YAG laser with appropriate parameters can be used as an alternative method for porcelain etching. PMID:24142046

Hosseini, Mohammad Hashem; Sobouti, Farhad; Etemadi, Ardavan; Chiniforush, Nasim; Shariati, Mahsa

2015-02-01

270

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

271

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

272

Monitoring Surface Deformation using Polarimetric Ground Based Interferometric Radar  

NASA Astrophysics Data System (ADS)

Surface deformation monitoring using ground based interferometric radar (GBIR) measurements may be desirable for a number of applications in the earth sciences. The University of Missouri (MU) research team has ongoing efforts to use the MU GBIR for monitoring surface deformation at a number of sites. Measurements have been collected at sites requiring access by various transportation means such as using off-road vehicle, hiking, and helicopter. Once on site, initial setup takes about 10 minutes. After setup, an image may be acquired by azimuth scan about every 20 seconds. The highly portable system lends itself to rapid deployment in remote environments and repeat survey sites. The MU GBIR's high portability and fast imaging capabilities allow rapid surveying and long-term surveying potential of surface deformation. Imagery may be formed in near real time for initial quick looks. After data collection, imagery data may be further enhanced by radiometric calibration, polarimetric calibration, and time-series analysis. Imaging may be acquired at the electromagnetic spectral bands of C-band and Ku-band. Prior demonstration of millimeter and better sensitivity to deformation over the course of a day of data collects has been performed using the MU GBIR. In addition, the MU GBIR can be removed and re-positioned at the same point with geodetic-grade precision for repeat surveys. Study results and additional development progress will be presented. This project is sponsored by a grant from the National Science Foundation.

Legarsky, J. J.; Gomez, F.; Rosenblad, B.; Loehr, E.; Cherukumilli, S.; Deng, H.; Held, B.; Jenkins, W.

2012-12-01

273

Small reactor power systems for manned planetary surface bases  

SciTech Connect

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, H.S.

1987-12-01

274

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

275

Spatial resolution in prism-based surface plasmon resonance microscopy.  

PubMed

Several optical surface sensing techniques, such as Surface Plasmon Resonance (SPR), work by imaging the base of a prism by one of its faces. However, such a fundamental optical concern has not been fully analyzed and understood so far, and spatial resolution remains a critical and controversial issue. In SPR, the propagation length L(x) of the surface plasmon waves has been considered as the limiting factor. Here, we demonstrate that for unoptimized systems geometrical aberrations caused by the prism can be more limiting than the propagation length. By combining line-scan imaging mode with optimized prisms, we access the ultimate lateral resolution which is diffraction-limited by the object light diffusion. We describe several optimized configurations in water and discuss the trade-off between L(x) and sensitivity. The improvement of resolution is confirmed by imaging micro-structured PDMS stamps and individual living eukaryote cells and bacteria on field-of-view from 0.1 to 20 mm(2). PMID:25321746

Laplatine, Loïc; Leroy, Loïc; Calemczuk, Roberto; Baganizi, Dieudonné; Marche, Patrice N; Roupioz, Yoann; Livache, Thierry

2014-09-22

276

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. PMID:21764442

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

2011-01-01

277

Surface-Based Assays for Enzyme Adsorption and Activity on Model Cellulose Films  

E-print Network

Cellulose Surfaces by Using Horizontal Dipping Procedure. Applicationand application of surface-based assays for elucidating cellulase kinetics on model films of cellulose.cellulose surface rather than solely with chain ends. Application

Maurer, Samuel Andrew

2012-01-01

278

A Complete Example of an Optimal Two-Bracket Income Tax  

E-print Network

A Complete Example of an Optimal Two-Bracket Income Tax Jean-François Wen Department of Economics tidy expressions for the Pareto e¢ cient tax structures and the optimal two- backet marginal tax rates in designing the personal income tax schedule. It forms a cornerstone of modern public ...nance and garnered

Habib, Ayman

279

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. PMID:25006465

Alsulaimani, Fahad F.

2014-01-01

280

AdaptiviTree: adaptive tree visualization for tournament-style brackets.  

PubMed

Online pick'em games, such as the recent NCAA college basketball March Madness tournament, form a large and rapidly growing industry. In these games, players make predictions on a tournament bracket that defines which competitors play each other and how they proceed toward a single champion. Throughout the course of the tournament, players monitor the brackets to track progress and to compare predictions made by multiple players. This is often a complex sensemaking task. The classic bracket visualization was designed for use on paper and utilizes an incrementally additive system in which the winner of each match-up is rewritten in the next round as the tournament progresses. Unfortunately, this representation requires a significant amount of space and makes it relatively difficult to get a quick overview of the tournament state since competitors take arbitrary paths through the static bracket. In this paper, we present AdaptiviTree, a novel visualization that adaptively deforms the representation of the tree and uses its shape to convey outcome information. AdaptiviTree not only provides a more compact and understandable representation, but also allows overlays that display predictions as well as other statistics. We describe results from a lab study we conducted to explore the efficacy of AdaptiviTree, as well as from a deployment of the system in a recent real-world sports tournament. PMID:17968054

Tan, Desney; Smith, Greg; Lee, Bongshin; Robertson, George

2007-01-01

281

A Longitudinal Study of Regional Bracket Equality in the NCAA Men's Basketball Tournament  

E-print Network

A Longitudinal Study of Regional Bracket Equality in the NCAA Men's Basketball Tournament John A that will be invited, as the non-automatic-qualifiers, to the NCAA men's basketball tournament. These are the positions Athletic Association (NCAA) basketball championship tournament was expanded from 8 to 16 teams in 1951

Trono, John A.

282

Weight-reduction design on mounting bracket of commercial vehicle cab  

Microsoft Academic Search

The mounting bracket is one of the most important connecting components in commercial vehicle cab. The FEM provides guidance for maximizing the effectiveness of weight reduction efforts on condition that the structure meets the requirements for strength, stiffness and vibration performance. The work presents two kinds of structural optimization methods, which are topology optimization and size optimization respectively, and introduces

Chen Jing; Li Zheng-mao; Wang Deng-feng; Wang Xin-Yu

2010-01-01

283

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

2011-10-01

284

Protein Based Localized Surface Plasmon Resonance Gas Sensing  

NASA Astrophysics Data System (ADS)

We apply the localized surface plasmon resonance (LSPR) of gold nanoparticles (GNPs) covalently coupled with cytochrome c (cyt c) to create a nanobiosensor for detecting hydrogen sulfide (H2S) in the range of 15–100 ppb. Monolayer formation of GNPs on glass surface functionalized with 3-aminopropyltrimethoxysilane (APTMS) is performed for fabricating a chip-based format of the optical transducer. By chemical introduction of short-chain thiol derivatives on cyt c protein shell via its lysine residues, a very fast self-assembled monolayer (SAM) of cyt c is formed on the GNPs. Significant shifts in the LSPR peak (??LSPR) are observed by reacting H2S with cyt c. Results show a linear relationship between ??LSPR and H2S concentration. Furthermore, shifts in the LSPR peak are reversible and the peak positions return to their pre-exposure values once the H2S is removed. The experimental results strongly indicate that the protein based LSPR chip can be successfully used as a simple, fast, sensitive and quantitative sensor for H2S detection.

Meisam, Omidi; Gh., Amoabediny; Yazdian, F.; Habibi-Rezaei, M.

2015-01-01

285

On the Canonical Structure of the De Donder-Weyl Covariant Hamiltonian Formulation of Field Theory I. Graded Poisson brackets and equations of motion  

Microsoft Academic Search

The analogue of the Poisson bracket for the De Donder-Weyl (DW) Hamiltonian formulation of field theory is proposed. We start from the Hamilton- Poincar\\\\'{e}-Cartan (HPC) form of the multidimensional variational calculus and define the bracket on the differential forms over the space-time (=horizontal forms). This bracket is related to the Schouten-Nijenhuis bracket of the multivector fields which are associated with

Igor V. Kanatchikov; RWTH Aachen

1993-01-01

286

Automatic Feature-based Surface Mapping for Brain Cortices  

Microsoft Academic Search

We present a method that maps a complex surface geometry to an equally complicated, similar surface. One main objective of our effort is to develop technology for automatically transferring surface annotations from an atlas brain to a subject brain. While macroscopic regions of brain surfaces often correspond, the detailed surface geometry of corresponding areas can vary greatly. We have developed

Fabien Vivodtzev; David F. Wiley; Lars Linsen; James Jones; Nina Amenta; Bernd Hamann; Kenneth I. Joy

287

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

288

Surface parameterization in volumetric images for curvature-based feature classification  

Microsoft Academic Search

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

Francis K. H. Quek; Richard W. I. Yarger; Cemil Kirbas

2003-01-01

289

A Optical Probe of Thin Film and Surface Contamination Based on Surface Plasmon Resonance.  

NASA Astrophysics Data System (ADS)

The microcontamination of optical surfaces or optical thin films affects many of their properties. In this work, we investigated several measurement systems to detect many types of surface contamination of coatings based on the surface plasmon resonance (SPR) phenomenon. The attenuated total reflection (ATR) coupling, also known as the Kretschmann configuration, excited the nonradiative surface plasmon wave for SPR measurement. Several microcontamination layers thinner than 10 nm were studied. The results showed that in all the cases SPR curves shifted to larger incident angles. From the amount of angle shift, the thickness of contamination was determined with a sensitivity of as little as one angstrom. The optical constants of those contamination layers were also derived. The shifts of the SPR curves served as an index for the efficiency of cleaning processes. It was found that the contamination by moisture can be removed with Iso-propyl alcohol by the ultrasonic cleaning process, while acetone was the more effective solvent in removing the contamination left by strippable coating residue show that the contamination layer was roughened by ultrasonic cleaning. In studies of island-like discontinuous thin layers of Ag, Al, and MgF_2, we found that the refractive index of MgF_2, a dielectric film material, slightly decreased as the thickness decreased, but for discontinuous metal films, the optical constants changed rapidly and became more dielectric in nature. Direct detection of contamination by coating processes in a small vacuum chamber was also carried out. In a chamber with high backstreaming from a diffusion pump, a broad SPR curve for an Ag film revealed obvious optical constant changes. Measuring and comparing the shift indicates that a significant amount of contamination was occurring right after the coating was completed. This suggests that for good evaporated optical thin films, it is important to have a more tightly controlled evaporation process. Finally, particulate, as well as layered, contamination can also be measured. A radiative SPR wave was generated by illuminating a contaminated surface. Similar radiative SPR waves also can be observed by adding a rough contaminant layer on an Ag film.

Wang, Ran-Hong Raymond

1990-01-01

290

Mapping ear canal movement using area-based surface matching  

NASA Astrophysics Data System (ADS)

Movement of the external ear canal, associated with jaw motion, relative to the concha region of the pinna has been studied. Pairs of open-jaw and closed-jaw impressions were taken of 14 ears from 10 subjects. Three-dimensional coordinate data were obtained from the concha and the anterior surface of the canal using a reflex microscope. Proprietary area-based matching software was used to evaluate distortion of the two surfaces between the two jaw positions. The canal data from each pair were placed into the same coordinate system with their respective concha regions aligned. Difference maps of the canal data were used to demonstrate the amount of anterior-posterior (A-P), superior-inferior (S-I), and medial-lateral (M-L) movement, relative to the concha, that occurred between the open- and closed-jaw impressions. The concha regions did not undergo significant deformation. The canal regions underwent varying amounts of deformation with all canals conforming within an rms of 136 ?m across the entire surface. The majority of canals underwent significant movement relative to the concha. M-L movement ranged from +2.0 to -3.8 mm; eight canals moved laterally, five moved medially, and two showed no movement. S-I movement ranged from +3.7 to -2.7 mm; nine canals moved inferiorly, two moved superiorly, and three showed no movement. A-P movement ranged between +7.5 and -8.5 mm, with five canals moving anteriorly, three posteriorly, and four in a mixed fashion. This study has shown the variability of canal movement relative to the concha and does not support previous reports that suggest that the ear canal only widens with jaw opening.

Grenness, Malcolm J.; Osborn, Jon; Weller, W. Lee

2002-02-01

291

Surface plasmon resonance based fiber optic refractive index sensors  

NASA Astrophysics Data System (ADS)

Refractive index sensors based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber are presented. The sensing element of the fiber optic SPR sensors is a bare core of a step-index optical fiber made of fused silica with a double-sided sputtered gold film. First, an in-line transmissionbased sensing scheme with the fiber optic SPR probe is used. Second, a reflection-based sensing scheme with a terminated fiber optic SPR probe is employed. The fiber optic SPR probes have different lengths and the thickness of the sputtered gold film is about 50 nm. Both sensing schemes utilize a wavelength interrogation method so that the refractive index of a liquid is sensed by measuring the position of the dip in the transmitted or reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured. For the transmission-based sensing scheme a polarization-dependent response is revealed.

Hlubina, Petr; Kadulova, Miroslava; Ciprian, Dalibor

2014-12-01

292

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. PMID:22163531

Christensen, Sune M.; Stamou, Dimitrios G.

2010-01-01

293

Polarimetric Ground Based Interferometric Radar for Surface Deformation Mapping  

NASA Astrophysics Data System (ADS)

Ground based interferometric radar (GBIR) measurements of surface deformation at sub-millimeter sensitivity may be desirable for a number of earth science applications including terrain mapping and monitoring of landslide movements. Through University of Missouri (MU) led efforts, a portable polarimetric GBIR has been developed for surface deformation mapping. Fully polarimetric capabilities allow the application of polarimetric interferometry, scatterer decomposition, and other advanced polarimetric methods. Using open literature techniques, polarimetric calibration and absolute radiometric calibration using known targets may be performed. The MU GBIR radiates electromagnetic waves at a number of free space wavelengths including C-band approximately 5.7 cm and Ku-band about 1.8 cm. The initial mechanical deployment setup time is typically about 10 minutes. For image formation, the MU GBIR employs azimuth scanning, which may collect data for a single pass interferogram in 20 seconds for a 180 degree azimuth sweep. Initial inteferograms may be formed at the deployment site in near real time. Moreover, the MU GBIR can be removed and re-positioned at the same point with relatively high (geodetic-grade) precision. A number of field experiments have been performed at various sites using the system. Demonstration of millimeter and better sensitivity to deformation over the course of a day of data collects has been performed at a test site using the MU GBIR. Study results and further development progress will be presented. This project is sponsored by a grant from the National Science Foundation.

Legarsky, J. J.; Gomez, F. G.; Rosenblad, B.; Loehr, E.; Deng, H.; Held, B.; Jenkins, W.

2011-12-01

294

Hippocampal shape analysis: surface-based representation and classification  

NASA Astrophysics Data System (ADS)

Surface-based representation and classification techniques are studied for hippocampal shape analysis. The goal is twofold: (1) develop a new framework of salient feature extraction and accurate classification for 3D shape data; (2) detect hippocampal abnormalities in schizophrenia using this technique. A fine-scale spherical harmonic expansion is employed to describe a closed 3D surface object. The expansion can then easily be transformed to extract only shape information (i.e., excluding translation, rotation, and scaling) and create a shape descriptor comparable across different individuals. This representation captures shape features and is flexible enough to do shape modeling, identify statistical group differences, and generate similar synthetic shapes. Principal component analysis is used to extract a small number of independent features from high dimensional shape descriptors, and Fisher's linear discriminant is applied for pattern classification. This framework is shown to be able to perform well in distinguishing clear group differences as well as small and noisy group differences using simulated shape data. In addition, the application of this technique to real data indicates that group shape differences exist in hippocampi between healthy controls and schizophrenic patients.

Shen, Li; Ford, James; Makedon, Fillia; Saykin, Andrew

2003-05-01

295

Multichannel surface electromyography classification based on muscular synergy.  

PubMed

With the aim to control a multiple degrees of freedom electromechanical devices, e.g., assistive robots, powered wheelchair, etc., this paper proposes a real-time multichannel surface electromyography classification scheme based on the coordination or synergies between a functional group of muscles: biceps brachii, triceps brachii, pronator teres, and brachioradialis. The muscular synergy is evaluated by the analysis of a multivariate function, composed by the four corresponding neuromuscular activation functions, and the cross-correlation matrix of muscular force estimated through the root mean square (RMS) value of sEMG amplitude. The resulting features from the training set were used to train an artificial neural network with classification accuracy up of 90%. PMID:21096390

Lopez, Natalia M; Orosco, Eugenio; di Sciascio, Fernando

2010-01-01

296

Infrared transparent frequency selective surface based on metallic meshes  

SciTech Connect

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 [Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China) [Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Xu, Nianxi; Liu, Hai; Gao, Jinsong, E-mail: gaojs@ciomp.ac.cn [Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China)] [Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China)

2014-02-15

297

Infrared transparent frequency selective surface based on iterative metallic meshes  

NASA Astrophysics Data System (ADS)

In this paper, we present an infrared transparent frequency selective surface (ITFSS) based on iterative metallic meshes, which possesses the properties of high transmittance in infrared band and band-pass effect in millimeter wave band. Cross-slot units are designed on the iterative metallic meshes, which is composed of two same square metallic meshes with a misplaced overlap. In the infrared band of 3–5 ?m, the ITFSS has an average transmittance of 80% with a MgF2 substrate. In the millimeter wave band, a transmittance of ?0.74 dB at the resonance frequency of 39.4 GHz is obtained. Moreover, theoretical simulations of the ITFSS diffractive characteristics and transmittance response are also investigated in detail. This ITFSS may be an efficient way to achieve the metamaterial millimeter wave/infrared functional film. Project supported by the National Natural Science Foundation of China (Grant No. 61401424).

Yu, Miao; Xu, Nian-Xi; Gao, Jin-Song

2015-03-01

298

The circular polarization interferometer based surface plasmon biosensor  

NASA Astrophysics Data System (ADS)

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 "OBMorph" includes a light source, an easy to use incident angle varying scheme based on a parabolic and a spherical mirrors, and prism coupled sample stages. To increase the metrology sensitivity, which depends on precisely control the angular resolution, a precision step-motor coupled with a parabolic mirror were used to control the incident angle accurately. By using fault tolerance algorithm, the imperfect adjustment of circular polarization interferometer was eliminated to obtain a perfect Lissajous curve needed for circular polarization interferometry. The instrument developed was shown to have resolution as high as 4.92×10-6 RIU. The effect that refractive index of ITO thin film changes with respect to externally applied voltage was also adopted by coating an ITO thin film onto biochips so as to shift the surface plasmon resonance angle for larger phase interrogation ranges. We successfully measured CRP and anti-CRP specific interaction in 0.75 ?g/ml ~ 400 ?g/ml ranges. In addition, the concentrations of tuberculosis inhibitor - DHFR and compound Mg2P4O7 that can interact with CYP450 were also quantified successfully. The OBMorph was shown to have potential applications in areas such as flat panel displays, optical coating, and drug delivery, to name a few.

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

2010-02-01

299

Chemical and Biological Sensing Based on the Surface Photovoltage Measurement of the Si Surface Potential Barrier  

NASA Astrophysics Data System (ADS)

Chemical and biological species deposited on the crystalline silicon surface created surface barrier changes that were detected using the non-contact Surface Photovoltage technique. The magnitude of the surface barrier modifications provided a signature allowing quantification of the sensed species. The simplicity and sensitivity of this technique offers an exciting opportunity for a new type of low cost sensing devices.

Nauka, K.; Li, Zhiyong; Kamins, T. I.

2005-06-01

300

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.

2012-02-01

301

ERT inversion with the incorporation of surface-based GPR  

NASA Astrophysics Data System (ADS)

The inversion of resistivity data produces smoothed results due to regularization. This potentially adds difficulty into interpretations if regions within the subsurface are separated by sharp boundaries. This problem is improved by incorporating prior information into the inversion. Prior information applied to such inversions have recently been obtained from other geophysical datasets, such as seismic, well-logs, or borehole-based GPR. I propose to incorporate data obtained from land-based GPR. This approach will achieve higher spatial resolutions, improved accuracy resistivity values, and more realistic models, and will be especially useful for near-surface geophysical investigations. The Boise Hydrogeophysical Research Site (BHRS) located in Boise, Idaho, is a well known area due to several previous studies at the site, and will be used to test the performance of this inversion method. An application study will also be conducted at a research site near the Bogus Basin recreational ski resort, located just outside of Boise, Idaho, where the inverted results will be used to estimate lateral variations in soil moisture of a hill slope during melt events of an overlying snowpack.

Hetrick, H. F.; Marshall, H.; Bradford, J. H.; Mead, J.

2013-12-01

302

Boundary Contour Based Surface Integration Affected by Color  

PubMed Central

The visual system represents occluded surfaces by integrating the visible and partially occluded fragments with reliance on surface boundary contours. Does surface integration also depend on color similarity? Using displays with aligned images, we found the visual system has a preference to integrate images with the same color to form occluded surfaces and construct illusory occluding surfaces. This results in enhanced shape discrimination of briefly presented stimuli, and a tendency to perceive global motion of the integrated fragments. The contribution of color to surface integration is observed both in equiluminous setting and in non-equiluminous setting where achromatic contrast exists. PMID:20558193

Su, Yong R; He, Zijiang J; Ooi, Teng Leng

2010-01-01

303

Determining surface areas of marine alga cells by acid-base titration method  

Microsoft Academic Search

A new method for determining the surface area of living marine alga cells was described. The method uses acid-base titration to measure the surface acid\\/base amount on the surface of alga cells and uses the BET (Brunauer, Emmett, and Teller) equation to estimate the maximum surface acid\\/base amount, assuming that hydrous cell walls have carbohydrates or other structural compounds which

Xiulin Wang; Yanjun Ma; Yuenlan Su

1997-01-01

304

Multivariate Tensor-based Brain Anatomical Surface Morphometry via Holomorphic  

E-print Network

surface morphometry in HIV/AIDS (19 subjects) and cortical surface morphometry in Williams Syndrome (WS (holomorphic one-forms). We performed three empirical studies of brain abnormalities in Williams syndrome (WS

Wang, Yalin

305

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

306

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

307

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

308

Poisson Bracket for Fermion Fields: Correspondence Principle, Second Class Constraints and Hamilton-Jacobi equation  

E-print Network

We introduce a symmetric Poisson bracket that allows us to describe anticommuting fields on a classical level in the same way as commuting fields, without the use of Grassmann variables. By means of a simple example, we show how the Dirac bracket for the elimination of the second class constraints can be introduced, how the classical Hamiltonian equations can be derived and how quantization can be achieved through a direct correspondence principle. Finally, we show that the semiclassical limit of the corresponding Schroedinger equation leads back to the Hamilton-Jacobi equation of the classical theory. Summarizing, it is shown that the relations between classical and quantum theory are valid for fermionic fields in exactly the same way as in the bosonic case, and that there is no need to introduce anticommuting variables on a classical level.

Leclerc, M

2012-01-01

309

Poisson Bracket for Fermion Fields: Correspondence Principle, Second Class Constraints and Hamilton-Jacobi equation  

E-print Network

We introduce a symmetric Poisson bracket that allows us to describe anticommuting fields on a classical level in the same way as commuting fields, without the use of Grassmann variables. By means of a simple example, we show how the Dirac bracket for the elimination of the second class constraints can be introduced, how the classical Hamiltonian equations can be derived and how quantization can be achieved through a direct correspondence principle. Finally, we show that the semiclassical limit of the corresponding Schroedinger equation leads back to the Hamilton-Jacobi equation of the classical theory. Summarizing, it is shown that the relations between classical and quantum theory are valid for fermionic fields in exactly the same way as in the bosonic case, and that there is no need to introduce anticommuting variables on a classical level.

M. Leclerc

2012-11-18

310

An in-process surface recognition system based on neural networks in end milling cutting operations  

Microsoft Academic Search

An in-process based surface recognition system to predict the surface roughness of machined parts in the end milling process was developed in this research to assure product quality and increase production rate by predicting the surface finish parameters in real time. In this system, an accelerometer and a proximity sensor are employed as in-process surface recognition sensors during cutting to

Yu-Hsuan Tsai; Joseph C. Chen; Shi-Jer Lou

1999-01-01

311

Comparison of clinical bracket point registration with 3D laser scanner and coordinate measuring machine  

PubMed Central

OBJECTIVE: The aim of the present study was to assess the diagnostic value of a laser scanner developed to determine the coordinates of clinical bracket points and to compare with the results of a coordinate measuring machine (CMM). METHODS: This diagnostic experimental study was conducted on maxillary and mandibular orthodontic study casts of 18 adults with normal Class I occlusion. First, the coordinates of the bracket points were measured on all casts by a CMM. Then, the three-dimensional coordinates (X, Y, Z) of the bracket points were measured on the same casts by a 3D laser scanner designed at Shahid Beheshti University, Tehran, Iran. The validity and reliability of each system were assessed by means of intraclass correlation coefficient (ICC) and Dahlberg's formula. RESULTS: The difference between the mean dimension and the actual value for the CMM was 0.0066 mm. (95% CI: 69.98340, 69.99140). The mean difference for the laser scanner was 0.107 ± 0.133 mm (95% CI: -0.002, 0.24). In each method, differences were not significant. The ICC comparing the two methods was 0.998 for the X coordinate, and 0.996 for the Y coordinate; the mean difference for coordinates recorded in the entire arch and for each tooth was 0.616 mm. CONCLUSION: The accuracy of clinical bracket point coordinates measured by the laser scanner was equal to that of CMM. The mean difference in measurements was within the range of operator errors. PMID:25741826

Nouri, Mahtab; Farzan, Arash; Baghban, Ali Reza Akbarzadeh; Massudi, Reza

2015-01-01

312

[Effect of thermoelectrochemical recycling treatment on direct orthodontic brackets: morphological and dimensional S.E.M. analysis].  

PubMed

The AA, analyze the effects of recycling treatment of orthodontic stainless direct brackets. The ESMA method has been utilized, by BIG JANE E3762. A morphological and dimensional analysis has been done, before and after recycling, by SEM. PMID:3079107

Laino, A; Sangiovanni, R; Manfredi, C; Michelotti, A; Valletta, R

1988-12-01

313

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

314

Graphene-based active slow surface plasmon polaritons  

NASA Astrophysics Data System (ADS)

Finding new ways to control and slow down the group velocity of light in media remains a major challenge in the field of optics. For the design of plasmonic slow light structures, graphene represents an attractive alternative to metals due to its strong field confinement, comparably low ohmic loss and versatile tunability. Here we propose a novel nanostructure consisting of a monolayer graphene on a silicon based graded grating structure. An external gate voltage is applied to graphene and silicon, which are separated by a spacer layer of silica. Theoretical and numerical results demonstrate that the structure exhibits an ultra-high slowdown factor above 450 for the propagation of surface plasmon polaritons (SPPs) excited in graphene, which also enables the spatially resolved trapping of light. Slowdown and trapping occur in the mid-infrared wavelength region within a bandwidth of ~2.1 ?m and on a length scale less than 1/6 of the operating wavelength. The slowdown factor can be precisely tuned simply by adjusting the external gate voltage, offering a dynamic pathway for the release of trapped SPPs at room temperature. The presented results will enable the development of highly tunable optoelectronic devices such as plasmonic switches and buffers.

Lu, Hua; Zeng, Chao; Zhang, Qiming; Liu, Xueming; Hossain, Md Muntasir; Reineck, Philipp; Gu, Min

2015-02-01

315

Cortical surface shape analysis based on spherical wavelets.  

PubMed

In vivo quantification of neuroanatomical shape variations is possible due to recent advances in medical imaging and has proven useful in the study of neuropathology and neurodevelopment. In this paper, we apply a spherical wavelet transformation to extract shape features of cortical surfaces reconstructed from magnetic resonance images (MRIs) of a set of subjects. The spherical wavelet transformation can characterize the underlying functions in a local fashion in both space and frequency, in contrast to spherical harmonics that have a global basis set. We perform principal component analysis (PCA) on these wavelet shape features to study patterns of shape variation within normal population from coarse to fine resolution. In addition, we study the development of cortical folding in newborns using the Gompertz model in the wavelet domain, which allows us to characterize the order of development of large-scale and finer folding patterns independently. Given a limited amount of training data, we use a regularization framework to estimate the parameters of the Gompertz model to improve the prediction performance on new data. We develop an efficient method to estimate this regularized Gompertz model based on the Broyden-Fletcher-Goldfarb-Shannon (BFGS) approximation. Promising results are presented using both PCA and the folding development model in the wavelet domain. The cortical folding development model provides quantitative anatomic information regarding macroscopic cortical folding development and may be of potential use as a biomarker for early diagnosis of neurologic deficits in newborns. PMID:17427744

Yu, Peng; Grant, P Ellen; Qi, Yuan; Han, Xiao; Ségonne, Florent; Pienaar, Rudolph; Busa, Evelina; Pacheco, Jenni; Makris, Nikos; Buckner, Randy L; Golland, Polina; Fischl, Bruce

2007-04-01

316

Detection of tonic epileptic seizures based on surface electromyography.  

PubMed

The purpose of this project was to design an algorithm for detection of tonic seizures based on surface electromyography signals from the deltoids. A successful algorithm has a future prospect of being implemented in a wearable device as part of an alarm system. This has already been done for generalized tonic-clonic seizures, and the hypothesis was that some of the same characteristics could be found for tonic seizures. The signals were pre-processed by a high-pass filter to remove low frequency noise such as movement artifacts. Several different features were investigated, including kurtosis, median frequency, zero crossing rate and approximate entropy. These features were used as input in the random forest classifier to decide if a data segment was from a seizure or not. The goal was to develop a generic algorithm for all tonic seizures, but better results were achieved when certain parameters were adapted specifically for each patient. With patient specific parameters the algorithm obtained a sensitivity of 100% for four of six patients with false detection rates between 0.08 and 7.90 per hour. PMID:25570115

Larsen, Sigge N; Conradsen, Isa; Beniczky, Sandor; Sorensen, Helge B D

2014-08-01

317

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

318

Safely Conducting Airport Surface Trajectory-Based Operations  

NASA Technical Reports Server (NTRS)

A piloted simulation study was conducted at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) to evaluate the ability to safely conduct surface trajectory-based operations (STBO) by assessing the impact of providing traffic intent information, conflict detection and resolution (CD&R) system capability, and the display of STBO guidance to the flight crew on both head-down and head-up displays (HUD). Nominal and off-nominal conflict scenarios were conducted using 12 airline crews operating in a simulated Memphis International Airport terminal environment. The flight crews met their required time-of-arrival at route end within 10 seconds on 98 percent of the trials, well within the acceptable performance bounds of 15 seconds. Traffic intent information was found to be useful in determining the intent of conflict traffic, with graphical presentation preferred. The CD&R system was only minimally effective during STBO because the prevailing visibility was sufficient for visual detection of incurring traffic. Overall, the pilots indicated STBO increased general situation awareness but also negatively impacted workload, reduced the ability to watch for other traffic, and increased head-down time.

Jones, Denise R.; Prinzel, Lawrence J., III; Bailey, Randall E.; Arthur, Jarvis J., III; Barnes, James R.

2014-01-01

319

Graphene-based active slow surface plasmon polaritons  

PubMed Central

Finding new ways to control and slow down the group velocity of light in media remains a major challenge in the field of optics. For the design of plasmonic slow light structures, graphene represents an attractive alternative to metals due to its strong field confinement, comparably low ohmic loss and versatile tunability. Here we propose a novel nanostructure consisting of a monolayer graphene on a silicon based graded grating structure. An external gate voltage is applied to graphene and silicon, which are separated by a spacer layer of silica. Theoretical and numerical results demonstrate that the structure exhibits an ultra-high slowdown factor above 450 for the propagation of surface plasmon polaritons (SPPs) excited in graphene, which also enables the spatially resolved trapping of light. Slowdown and trapping occur in the mid-infrared wavelength region within a bandwidth of ~2.1??m and on a length scale less than 1/6 of the operating wavelength. The slowdown factor can be precisely tuned simply by adjusting the external gate voltage, offering a dynamic pathway for the release of trapped SPPs at room temperature. The presented results will enable the development of highly tunable optoelectronic devices such as plasmonic switches and buffers. PMID:25676462

Lu, Hua; Zeng, Chao; Zhang, Qiming; Liu, Xueming; Hossain, Md Muntasir; Reineck, Philipp; Gu, Min

2015-01-01

320

Retention of features on a mapped Drosophila brain surface using a Bézier-tube-based surface model averaging technique.  

PubMed

Model averaging is a widely used technique in biomedical applications. Two established model averaging methods, iterative shape averaging (ISA) method and virtual insect brain (VIB) method, have been applied to several organisms to generate average representations of their brain surfaces. However, without sufficient samples, some features of the average Drosophila brain surface obtained using the above methods may disappear or become distorted. To overcome this problem, we propose a Bézier-tube-based surface model averaging strategy. The proposed method first compensates for disparities in position, orientation, and dimension of input surfaces, and then evaluates the average surface by performing shape-based interpolation. Structural features with larger individual disparities are simplified with half-ellipse-shaped Bézier tubes, and are unified according to these tubes to avoid distortion during the averaging process. Experimental results show that the average model yielded by our method could preserve fine features and avoid structural distortions even if only a limit amount of input samples are used. Finally, we qualitatively compare our results with those obtained by ISA and VIB methods by measuring the surface-to-surface distances between input surfaces and the averaged ones. The comparisons show that the proposed method could generate a more representative average surface than both ISA and VIB methods. PMID:22922691

Chen, Guan-Yu; Wu, Cheng-Chi; Shao, Hao-Chiang; Chang, Hsiu-Ming; Chiang, Ann-Shyn; Chen, Yung-Chang

2012-12-01

321

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

322

Superhydrophobic alumina surface based on stearic acid modification  

NASA Astrophysics Data System (ADS)

A novel superhydrophobic alumina surface is fabricated by grafting stearic acid layer onto the porous and roughened aluminum film. The chemical and phase structure, morphology, and the chemical state of the atoms at the superhydrophobic surface were investigated by techniques as FTIR, XRD, FE-SEM, and XPS, respectively. Results show that a super water-repellent surface with a contact angle of 154.2° is generated. The superhydrophobic alumina surface takes on an uneven flowerlike structure with many nanometer-scale hollows distribute in the nipple-shaped protrusions, and which is composed of boehmite crystal and ?-Al2O3. Furthermore, the roughened and porous alumina surface is coated with a layer of hydrophobic alkyl chains which come from stearic acid molecules. Therefore, both the roughened structure and the hydrophobic layer endue the alumina surface with the superhydrophobic behavior.

Feng, Libang; Zhang, Hongxia; Mao, Pengzhi; Wang, Yanping; Ge, Yang

2011-02-01

323

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

324

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

325

A novel monopole-alike surface-wave antennas designed based on periodic structures  

Microsoft Academic Search

From applications of high-impedance surfaces, TM surface wave pass-band below TM band-gap was found, and for periodic artificial surfaces without a band-gap, a similar phenomenon can be found below the leaky-wave band, which form the primary discovered special features in the present research work. A novel type of surface-wave antenna based on artificial surface was built, the antenna, which has

Ke Xiao; Le-Wei Li; Fei Zhao; Shun-Lian Chai; Jun-Jie Mao

2011-01-01

326

Surface Reconstruction with Feature Preservation based on Graph-cuts  

E-print Network

, the surface reconstruction attempts to make the unorganized data points to be "perceptible" by machines is to reconstruct the surface as faithful as possible from the data set with some interruptions such as noise specific applica- tions such as computer-aided design (CAD). The sharp features represent the high

Soatto, Stefano

327

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

328

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

329

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

330

GPU Based Fluid Animation over Elastic Surface Models  

Microsoft Academic Search

In this work, we focus on flow animation in elastic surfaces described by mass-spring models for computer game applications. We propose the combination of an efficient fluid model, that does not require solution of complicated equations, with a mass-spring approach to simulate the deformable surface. Firstly, we describe the fluid model for simulating the flow and its GPU implementation. The

B. B. S. Coutinho; G. A. Giraldi; A. L. Apolinario

2009-01-01

331

EPS control technology based on road surface conditions  

Microsoft Academic Search

An Electric Power Steering (EPS) System will be considered in this paper. We will discuss electrical power steering (EPS) design by utilizing information related to road surface conditions. Information regarding varying road surface conditions includes both pertinent information and ineffective information, which can be separated by frequency. These frequencies can be utilized in designing an EPS system more effectively in

Zhao Yan; Cheng Yi; Wang Hong

2009-01-01

332

Shading-Based Surface Editing Yotam Gingold and Denis Zorin  

E-print Network

a system for free-form surface modeling that allows a user to modify a shape by changing its rendered types of free-form surface edits which may be difficult to cast in terms of standard deformation Three-dimensional models are often created and manipulated using two-dimensional interfaces. User

Mohri, Mehryar

333

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

334

FEATURE ARTICLE Unified Molecular Picture of the Surfaces of Aqueous Acid, Base, and Salt Solutions  

E-print Network

FEATURE ARTICLE Unified Molecular Picture of the Surfaces of Aqueous Acid, Base, and Salt Solutions inorganic ions. Molecular dynamics calculations show that in salt solutions and bases the positively charged, consequently, these acids (unlike bases and salts) reduce the surface tension of water. The results

335

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

336

Ultranarrow band absorbers based on surface lattice resonances in nanostructured metal surfaces.  

PubMed

Nanostructured metals have received a significant amount of attention in recent years due to their exciting plasmonic and photonic properties enabling strong field localization, light concentration, and strong absorption and scattering at their resonance frequencies. Resonant plasmonic and metamaterial absorbers are of particular interest for applications in a wide variety of technologies including photothermal therapy, thermophotovoltaics, heat-assisted magnetic recording, hot-electron collection, and biosensing. However, it is rather challenging to realize ultranarrow absorption bands using plasmonic materials due to large optical losses in metals that decrease the quality factor of optical resonators. Here, we theoretically and experimentally demonstrate an ultranarrow band absorber based on the surface lattice resonances (SLRs) in periodic nanowire and nanoring arrays on optically thick, reflecting metallic films. In experiments, we observed ultranarrow band resonant absorption peaks with a bandwidth of 12 nm and absorption amplitude exceeding 90% at visible frequencies. We demonstrate that the resonance absorption wavelength, amplitude of the absorption peak, and the bandwidth can be controlled by tuning the periodicity and the thickness of nanoring and nanowire arrays. Unlike conventional plasmonic absorbers utilizing common metal–insulator–metal stacks, our narrow band absorber consists solely of metals, facilitating stronger optical interaction between the SLR of periodic nanostructures and the highly reflective film. Moreover, by introducing asymmetry to the nanoring/nanowire hybrid system, we observe the spectral evolution of resonance splitting enabled by strong coupling between two individual SLRs arising from nanoring and nanowire arrays. Designing such all-metallic nanostructure arrays is a promising route for achieving ultranarrow band absorbers which can be used as absorption filters, narrow band thermal emitters in thermophotovoltaics, and plasmonic biosensors. PMID:25072803

Li, Zhongyang; Butun, Serkan; Aydin, Koray

2014-08-26

337

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

338

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

SciTech Connect

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 [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191 (China); Wang Weihua [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Jiang Lei [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2011-12-26

339

Cauchy problem as a two-surface based `geometrodynamics'  

E-print Network

Four-dimensional spacetimes foliated by a two-parameter family of homologous two-surfaces are considered in Einstein's theory of gravity. By combining a 1+(1+2) decomposition, the canonical form of the spacetime metric and a suitable specification of the conformal structure of the foliating two-surfaces a gauge fixing is introduced. It is shown that, in terms of the chosen geometrically distinguished variables, the 1+3 Hamiltonian and momentum constraints can be recast into the form of a parabolic equation and a first order symmetric hyperbolic system, respectively. Initial data to this system can be given on one of the two-surfaces foliating the three-dimensional initial data surface. The 1+3 reduced Einstein's equations are also determined. By combining the 1+3 momentum constraint with the reduced system of the secondary 1+2 decomposition a mixed hyperbolic-hyperbolic system is formed. It is shown that solutions to this mixed hyperbolic-hyperbolic system are also solutions to the full set of Einstein's equations provided that the 1+3 Hamiltonian constraint is solved on the initial data surface $\\Sigma_0$ and the 1+2 Hamiltonian and momentum type expressions vanish on a world-tube yielded by the Lie transport of one of the two-surfaces foliating $\\Sigma_0$ along the time evolution vector field. Whenever the foliating two-surfaces are compact without boundary in the spacetime and a regular origin exists on the time-slices---this is the location where the foliating two-surfaces smoothly reduce to a point---it suffices to guarantee that the 1+3 Hamiltonian constraint holds on the initial data surface. A short discussion on the use of the geometrically distinguished variables in identifying the degrees of freedom of gravity are also included.

István Rácz

2014-12-06

340

Surfaces  

E-print Network

Surfaces is a collection of four individual essays which focus on the characteristics and tactile qualities of surfaces within a variety of perceived landscapes. Each essay concentrates on a unique surface theme and purpose; ...

DeMaio, Ernest Vincent, 1964-

1989-01-01

341

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

342

RTM-based Teleseismic Reflection Tomography with Free Surface Multiples  

NASA Astrophysics Data System (ADS)

Receiver function analysis of teleseismic converted and free surface reflected phases has long been a cornerstone of lithospheric studies. Discontinuities in elastic properties are revealed by deconvolving the incident wavefield from scattered phases and projecting the time differences to depth to form an image. The accuracy of the image is determined to a large extent by the accuracy of the method and background velocity model used, but popular approaches for projecting receiver functions to depth commonly rely on simplifying assumptions of a 1D velocity and planar discontinuities. In tectonically complex regions like subduction zones and rift systems, strong heterogeneity can create an ambiguous tradeoff between the background velocity and the depth of the discontinuities. Furthermore, such structures are apt to create caustics at high frequencies, rendering ray-based methods inadequate. In order to better constrain the background velocity and correctly place the discontinuities at depth, we employ a novel reverse-time migration (RTM) based reflection tomography method. We adapt our reflection tomography from exploration seismology for use with teleseismic phases. Active source methods for exploration have focused on the annihilation of extended images - image gathers formed with different subsurface angle or offset information - as a means of judging the accuracy of the model. Applying these approaches to teleseismic data is untenable because 1) the sparse and uneven distribution of earthquake sources leads to the incomplete construction of extended image, 2) the imperfect separation and source deconvolution of the scattered wavefield render previous error measurements unreliable, and 3) the planar geometry of incoming arrivals makes measures of subsurface offset insensitive to perturbations in the model. To overcome these obstacles, we have developed a flexible approach based on pairwise single-source image correlations. We determine the success of the RTM and thus the accuracy of the background velocity model by cross-correlation of the images produced using different teleseismic sources. Single-source images are created by propagating the incident and scattered wavefields to depth using a Helmholtz operator and combining the by applying an inverse scattering operator. The error function is then comprised of the weighted image correlation power at depth windows. The optimized velocity model is the one that minimizes power in the correlations away from zero depth shift. We develop our inversion scheme using the Augmented Lagrangian method and solve by conjugate gradient on a spline basis. We present details of the method and a 2D application to data from LA RISTRA in the western United States. In order to be effective in 2D, we require teleseismic phases arriving at the array at a broad sweep of incidence angles. With the Andean and Aleutian subduction zones along the strike of the array between 35° and 85° epicentral distance, LA RISTRA provides the ideal illumination for a tomographic inversion.

Burdick, S. A.; De Hoop, M. V.; van der Hilst, R. D.

2013-12-01

343

A “self-pinning” adhesive based on responsive surface wrinkles  

E-print Network

Surface wrinkles are interesting since they form spontaneously into well-defined patterns. The mechanism of formation is well-studied and is associated with the development of a critical compressive stress that induces the ...

Chan, Edwin P.

344

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

345

Contour-based surface reconstruction using MPU implicit models  

Microsoft Academic Search

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 R3 and employs Multi-level Partition of Unity (MPU) implicit models to create a surface that approximately fits to the 3D points. Since

Ilya Braude; Jeffrey Marker; Ken Museth; Jonathan Nissanov; David E. Breen

2007-01-01

346

Arc Length Based Grid Distribution For Surface and Volume Grids  

NASA Technical Reports Server (NTRS)

Techniques are presented for distributing grid points on parametric surfaces and in volumes according to a specified distribution of arc length. Interpolation techniques are introduced which permit a given distribution of grid points on the edges of a three-dimensional grid block to be propagated through the surface and volume grids. Examples demonstrate how these methods can be used to improve the quality of grids generated by transfinite interpolation.

Mastin, C. Wayne

1996-01-01

347

Surface characterization of functionalized imidazolium-based ionic liquids.  

PubMed

The surface composition of oligo(ethylene glycol) ether functionalized bis(trifluoromethylsulfonyl)imide ionic liquids has been studied by means of X-ray photoelectron spectroscopy (XPS). For [Me(EG)MIM][Tf 2N], [Et(EG) 2MIM][Tf 2N], and [Me(EG) 3MIM][Tf 2N], which vary by the number of ethylene glycol (EG) units (from 1 to 3), we have shown that the stoichiometry of the surface near region is in excellent agreement with the bulk stoichiometry, which confirms the high purity of the ionic liquid samples investigated and rules out pronounced surface orientation effects. This has been deduced from the experimental observation that the angle-resolved XP spectra of all elements present in the IL anions and cations (C, N, O, F, S) show identical signals in the bulk and surfaces sensitive geometry, i.e., at 0 degrees and 70 degrees emission angle, respectively. The relative intensity ratios of all elements were found to be in nearly perfect agreement with the nominal values for the individual ILs. In contrast to these findings, we identified surface-active impurities in [Me(EG)MIM]I, which is the starting material for the final anion exchange step to synthesize [Me(EG)MIM][Tf 2N]. Sputtering of the surface led to a depletion of this layer, which however recovered with time. The buildup of this contamination is attributed to a surface enrichment of a minor bulk contamination that shows surface activity in the iodide melt. PMID:18672915

Kolbeck, Claudia; Killian, Manuela; Maier, Florian; Paape, Natalia; Wasserscheid, Peter; Steinrück, Hans-Peter

2008-09-01

348

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

349

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

350

The effect of perturbations on resistance to sliding in second-order moments comparing two different bracket types  

PubMed Central

Orthodontic literature has shown all ligation methods to behave similarly in the clinical situation; however, the reasoning behind this still requires further investigation. A novel frictional device able to measure forces at the level of the bracket along with a custom perturbation device was used to investigate the effect of perturbations on resistance to sliding (RS) using conventional and passive ligated brackets. 150 3M Victory Series twins (0.022 slot) and 150 Damon Q brackets (0.022 slot) were tested using an 0.018 x 0.025 stainless steel wire for RS. There were 5 test groups consisting of equal numbers (n=30) representing combinations of high and low amplitude and frequency of perturbations along with a control. Second order angulation tested ranged from 0 to 6 degrees. Results for conventional brackets in the presence of perturbations at 0 degrees showed there was a statistically significant reduction (P<0.001) in RS when compared to controls. At 6 degrees, this difference (P<0.001) was seen in both high perturbation groups and one of the low perturbation groups. For passive ligated brackets, no statistically significant difference between groups was seen at 0 degrees. However, at 6 degrees high perturbation groups both resulted in statistically significant (P<0.001) reductions in RS when compared to controls. From this study it was concluded that passive ligated brackets have a lower RS when compared to conventional ligated brackets under all test conditions and angulations. Also, amplitude of perturbations has a larger role than frequency in reduction of RS values. PMID:25395993

Wong, Justin K; Romanyk, Dan L; Toogood, Roger W; Heo, Giseon; Carey, Jason P

2014-01-01

351

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

352

Linseed Oil-Based Concrete Surface Treatment -for Building and Highway Structures in  

E-print Network

, Linseed Oil-Based Concrete Surface Treatment -for Building and Highway Structures in Hong Kong Y, The University ofManitoba This experimental program investigated the effectiveness oj concrete sUrface treatment Keywords: Unseed Oil, Concrete Surface Treatment, Salt Spray Resistance, Carbonation, Bond Strength, Ultra

353

Automotive crashworthiness design using response surface-based variable screening and optimization  

Microsoft Academic Search

Purpose – The purpose of this paper is to provide a methodology with which to perform variable screening and optimization in automotive crashworthiness design. Design\\/methodology\\/approach – The screening method is based on response surface methodology in which linear response surfaces are used to create approximations to the design response. The response surfaces are used to estimate the sensitivities of the

K. J. Craig; Nielen Stander; D. A. Dooge; S. Varadappa

2005-01-01

354

Superomniphobic, transparent, and antireflection surfaces based on hierarchical nanostructures.  

PubMed

Optical surfaces that can repel both water and oil have much potential for applications in a diverse array of technologies including self-cleaning solar panels, anti-icing windows and windshields for automobiles and aircrafts, low-drag surfaces, and antismudge touch screens. By exploiting a hierarchical geometry made of two-tier nanostructures, primary nanopillars of length scale ? 100-200 nm superposed with secondary branching nanostructures made of nanoparticles of length scale ? 10-30 nm, we have achieved static contact angles of more than 170° and 160° for water and oil, respectively, while the sliding angles were lower than 4°. At the same time, with respect to the initial flat bare glass, the nanotextured surface presented significantly reduced reflection (<0.5%), increased transmission (93.8% average over the 400 to 700 nm wavelength range), and very low scattering values (about 1% haze). To the authors' knowledge, these are the highest optical performances in conjunction with superomniphobicity reported to date in the literature. The primary nanopillars are monolithically integrated in the glass surface using lithography-free metal dewetting followed by reactive ion etching,1 while the smaller and higher surface area branching structure made of secondary nanoparticles are deposited by the NanoSpray2 combustion chemical vapor deposition (CCVD). PMID:24988148

Mazumder, Prantik; Jiang, Yongdong; Baker, David; Carrilero, Albert; Tulli, Domenico; Infante, Daniel; Hunt, Andrew T; Pruneri, Valerio

2014-08-13

355

Superhydrophobic surface directly created by electrospinning based on hydrophilic material  

Microsoft Academic Search

We describe a method to form hydrophobic surfaces using PHBV (Poly (hydroxybutyrate-co-hydroxyvalerate))—a kind of intrinsically\\u000a hydrophilic material. The concentration of polymer solutions was varied to control the surface morphology and resultant wetting\\u000a property. The as-prepared films were characterized by micro-scale valley-and-hill structure, which was formed by aggregating\\u000a of electrospun beads. The bead morphology changed from smooth to porous and popcorn-like

Meifang Zhu; Weiwei Zuo; Hao Yu; Wen Yang; Yanmo Chen

2006-01-01

356

Explicit bracket in the exceptional simple Lie superalgebra cvect(0|3)_*  

E-print Network

This note is devoted to a more detailed description of one of the five simple exceptional Lie superalgebras of vector fields, cvect(0|3)_*, a subalgebra of vect(4|3). We derive differential equations for its elements, and solve these equations. Hence we get an exact form for the elements of cvect(0|3)_*. Moreover we realize cvect(0|3)_* by "glued" pairs of generating functions on a (3|3)-dimensional periplectic (odd symplectic) supermanifold and describe the bracket explicitly.

Irina Shchepochkina; Gerhard Post

1997-03-18

357

Probability Bracket Notation, Term Vector Space, Concept Fock Space and Induced Probabilistic IR Models  

E-print Network

After a brief introduction to Probability Bracket Notation (PBN) for discrete random variables in time-independent probability spaces, we apply both PBN and Dirac notation to investigate probabilistic modeling for information retrieval (IR). We derive the expressions of relevance of document to query (RDQ) for various probabilistic models, induced by Term Vector Space (TVS) and by Concept Fock Space (CFS). The inference network model (INM) formula is symmetric and can be used to evaluate relevance of document to document (RDD); the CFS-induced models contain ingredients of all three classical IR models. The relevance formulas are tested and compared on different scenarios against a famous textbook example.

Xing M. Wang

2011-06-19

358

Three-dimensional ray tracing on Delaunay-based reconstructed surfaces  

Microsoft Academic Search

A method of ray tracing for free-form optical surfaces has been developed. The ray tracing through such surfaces is based on Delaunay triangulation of the discrete data of the surface and is related to finite-element modeling. Some numerical examples of applications to analytical, noisy, and experimental free-form surfaces (in particular, a corneal topography map) are presented. Ray-tracing results (i.e., spot

Sergio Ortiz; Damian Siedlecki; Laura Remon; Susana Marcos

2009-01-01

359

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

2014-09-01

360

Orthodontic bracket shear bond strengths produced by two high-power light-emitting diode modes and halogen light.  

PubMed

The aim of this in vitro study was to compare the shear bond strength of orthodontic brackets cured with two different high-power light-emitting diode (LED) polymerization modes with traditional halogen polymerization. A total of forty-five extracted human premolar teeth were randomly divided into three groups. Each group consisted of 15 teeth mounted in an acrylic block. Following a standard enamel etching protocol, orthodontic brackets were cured on the first group of teeth with fast-mode LED, the second group with soft-start mode LED, and on the last group with a halogen light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. The results showed that brackets cured with soft-start mode LED produced the highest shear bond strengths (23.86 +/- 6.20 MPa). No significant difference was found between fast-mode LED (17.14 +/- 5.75 MPa) and the halogen group (17.38 +/- 5.41 MPa) (P > .05). The LED is effective for bonding metal brackets to teeth, and the soft-start mode gives higher bond strengths than the fast mode. PMID:16283816

Türkkahraman, Hakan; Küçüke?men, H Cenker

2005-09-01

361

A surface-based electrophysiology model relying on asymptotic analysis and motivated by cardiac atria modeling  

E-print Network

, the cardiac muscle cells, see e.g. [16, 15, 19, 3] and references therein. Given the frequent occurrenceA surface-based electrophysiology model relying on asymptotic analysis and motivated by cardiac a surface-based electrophysiology formulation, motivated by the modeling of thin structures such as cardiac

362

The Rhetorical Parsing of Unrestricted Texts: A Surface-based Approach  

E-print Network

The Rhetorical Parsing of Unrestricted Texts: A Surface-based Approach Daniel Marcu* Information well-formed rhetorical structures can be automatically derived by means of surface-form-based algorithms. These algorithms identify discourse usages of cue phrases and breaksentences into clauses, hy

Toronto, University of

363

Acid-base properties of the surface of the ?-Al2O3 suspension  

NASA Astrophysics Data System (ADS)

The distribution of the acid-base centers on the surface of ?-Al2O3 suspension particles was studied by potentiometric titration, and the corresponding p K spectra were constructed. It was inferred that the double electric layer created by the supporting electrolyte substantially affected the screening of the acid-base centers on the particle surface of the suspension.

Ryazanov, M. A.; Dudkin, B. N.

2009-12-01

364

Water-Vapor Plasma-Based Surface Activation for Trichlorosilane Modification of PMMA  

E-print Network

Water-Vapor Plasma-Based Surface Activation for Trichlorosilane Modification of PMMA Timothy M in polymer-based CE systems can be achieved by surface potential alteration through chemical modification hasbecomeincreasinglyimportantfortheenvironmentaldetection of chemical3 and biological4 warfare threats, as well as biological assays of DNA5 and proteins6

365

PHYSICALLY BASED ESTIMATION OF BARE SURFACE SOIL MOISTURE WITH THE PASSIVE RADIOMETERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A physically based bare surface soil moisture inversion technique for application with passive microwave satellite measurements including AMSR-E, SSM/I, SSMR and TMI was developed in this study. The inversion technique is based on the concept of a simple parameterized surface emission model, the Qp ...

366

Toward physically based estimation of surface irrigation infiltration  

Technology Transfer Automated Retrieval System (TEKTRAN)

Irrigation practitioners continue to use empirical infiltration equations. Theoretical infiltration equations are currently not capable of capturing surface irrigation infiltration behaviour, particularly at short times. An example is shown where the Green-Ampt equation can be adjusted to match fiel...

367

Reconfigurable active reflector based on High Impedance Surface  

Microsoft Academic Search

In this paper, the manufacturing and testing of a prototype concluding the development of a waveguide fed active antenna using an active High Impedance Surface (HIS) as main reflector are reported. The capability of such an antenna to generate various types of radiation beam (focalised, scanned…) has been demonstrated.

P. Ratajczak; J. M. Baracco; P. Brachat; J. M. Fargeas

2010-01-01

368

Surface-enhanced Raman spectroscopy of DNA bases  

Microsoft Academic Search

A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS spectrum new lines, not visible in the solution spectrum, appear while some lines visible

C. Otto; Tweel van den T. J. J; Mul de F. F. M; J. Greve

1986-01-01

369

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

370

Comparing Roughness Metrics with Geometric-based Roughness Lengths for a Snowpack Surface  

NASA Astrophysics Data System (ADS)

The snow surface is the interface between the atmosphere and the snowpack, and it is the location of the latent and sensible heat transfer, driven by the overlying wind. The wind speed can be dictated by the surface roughness. The aerodynamic roughness length is used to estimate the aforementioned heat fluxes, and, while values over three orders of magnitude are reported in the literature, most modeling efforts use a constant value over time and space. Here, two surface forms were measured using a Terrestrial Laser Scanner (TLS): a manually-altered "rough" surface and an undisturbed "smooth" surface. These TLS data were collected at Somport in the French Pyrenees Mountains in March 2012. Each surface was used to estimate the geometric-based (also morphometric) aerodynamic roughness length using two methods (height based and frontal area index) and three roughness metrics (random roughness, autocorrelation, fractal dimension). Since the spacing of surface snowpack data is often large, the TLS data were randomly subset at various resolutions and interpolated using several standard techniques. Each interpolated rough and smooth surface was evaluated based on the geometric roughness lengths and roughness metrics. When the interpolated subsetted surface adequately resembled the complete TLS surface (based on spatial statistics), the roughness metrics are well correlated to the geometric roughness length. Both the interpolation procedure and the resolution of the data are important to generate an adequate snow surface, as has been shown by previous snow depth interpolation research.

Fassnacht, S. R.; Oprea, I.; Sadre-Marandi, F.; Lopez Moreno, J.; Revuelto, J.; Webb, R.; Dangelmayr, G.

2012-12-01

371

Sketch and constraint-based design of B-spline surfaces  

Microsoft Academic Search

This paper describes a sketch- and constraint-based approach to editing of free-form curves and surfaces. We present a simple touch-and-replace technique to edit 2D and 3D curves. We introduce auxiliary surfaces that allow for a reliable interpretation of users' pen-strokes in 3D and we present a new method for sketch-and constraint-based surface sculpting.

Paul Michalik; Dae-Hyun Kim; Beat D. Bruderlin

2002-01-01

372

Polyurethane-based polymer surface modifiers with alkyl ammonium copolyoxetane soft segments: Reaction engineering, surface morphology and antimicrobial behavior  

NASA Astrophysics Data System (ADS)

Concentrating quaternary (positive) charge at polymer surfaces is important for applications including layer-by-layer polyelectrolyte deposition and antimicrobial coatings. Prior techniques to introduce quaternary charge to the surface involve grafting of quaternary ammonium moieties to a substrate or using polyurethanes with modified hard segments however there are impracticalities involved with these techniques. In the case of the materials discussed, the quaternary charge is introduced via polyurethane based polymer surface modifiers (PSMs) with quaternized soft segments. The particular advantage to this method is that it utilizes the intrinsic phase separation between the hard and soft segments of polyurethanes. This phase separation results in the surface concentration of the soft segments. Another advantage is that unlike grafting, where modification has to take place after device fabrication, these PSMs can be incorporated with the matrix material during device fabrication. The soft segments of these quaternized polyurethanes are produced via ring opening co-polymerization of oxetane monomers which possess either a trifluoroethoxy (3FOx) side chains or a quaternary ammonium side chain (C12). These soft segments are subsequently reacted with 4,4'-(methylene bis (p-cyclohexyl isocyanate)), HMDI and butanediol (BD) to form the PSM. It was initially intended to increase the concentration of quaternary ammonium charge by increasing PSM soft segment molecular weight. Unexpectedly, produced blends with surface microscale phase separation. This observation prompted further investigation of the effect of PSM soft segment molecular weight on phase separation in PSM-base polyurethane blends and the subsequent effects of this phase separation on the biocidal activity. Analysis of the surface morphology via tapping mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) revealed varying complexities in surface morphology as a function of the PSM soft segment molecular weight and initial annealing temperature. Many of these features include what are described as nanodots (100-300 nm), micropits (0.5-2 mum) and micropeaks (1-10 mum). It was also observed that surface morphology continued to coarsen with time and that the larger features were typically observed in blends containing PSMs with low molecular weight soft segments. This appearance of surface morphological feature correlates with decreased biocidal activity of the PSM blends, that is, the PSM blends exhibit little to no activity upon development of phase separated features. A model has been developed for phase separation and concomitant reduction of surface quaternary charge. This model points the way to future work that will stabilize surface charge and provide durability of surface modification.

Brunson, Kennard Marcellus, Jr.

373

Studying protein structural changes based on surface plasmon resonance and surface-enhanced Raman scattering  

NASA Astrophysics Data System (ADS)

The ability to recognize the conformational changes and structural variations of a protein when immobilized in a solid surface is of great importance in a variety of applications. Surface plasmon resonance (SPR) sensing is an appropriate technique for investigating interfacial phenomena, and enables the conformational changes of proteins to be monitored through the variation in the SPR angle shift. Meanwhile, the surface-enhanced Raman scattering (SERS) system can also assist in clarifying the changes in protein structure. The present study utilizes a 1 mM CrO3 phosphate buffer solution (PBS) to induce conformational changes of human serum albumin (HSA). Monitoring the corresponding SPR angle shifts and the SPR reflectivity spectrum enables the relationships between the conformational changes of the surface-immobilized protein and the thickness and dielectric constants of the protein layer to be estimated. The experimental SPR results indicate that the Cr6+ ions cause significant conformational change of the protein. It is established that the ions are not merely absorbed into the protein as a result of electrostatic forces, but that complex protein refolding events also take place. Furthermore, the data acquired from the SERS system yield valuable information regarding the changes which take place in the protein structure.

Hu, Wen-Pin; Chen, Shean-Jen; Yih, Jenq-Nan; Lin, G.-Y.; Chang, Guan L.

2004-06-01

374

Optical Sensing and Trapping Based on Localized Surface Plasmons  

NASA Astrophysics Data System (ADS)

This project involves the study of novel plasmonic nanodevices that provide unique functionality in optical sensing, surface-enhanced Raman scattering (SERS), and optical trapping. The first design is based on a coupling system involving double-layered metal nano-strips arrays. This system has the advantages of simple geometry and direct integration with microfluidic chips. The intense optical localization due to field coupling within the system can enhance detection sensitivity of target molecules, especially by virtue of the optical trapping of plasmonic nanoparticles. The optical resonant condition is obtained theoretically through analyzing the SPs modes. Numerical modeling based on two-dimensional (2D) finite-difference time-domain (FDTD) is consistent with the theoretical analysis and demonstrates the feasibility of using this system for optical sensing and trapping. In the second design, a gold nano-ring structure is demonstrated to be an effective approach for plasmonic nano-optical tweezers (PNOTs) for trapping metallic nanoparticles. In our demonstration example, we have optimized a device for SERS operation at the wavelength of 785 nm. Three-dimensional (3D) FDTD techniques have been employed to calculate the optical response, and the optical force distribution have been derived using the Maxwell stress tensor (MST) method. Simulation results indicate that the nano-ring produces a maximum trapping potential well of ~32 kBT on a 20 nm gold nanoparticle. The existence of multiple potential well results in a very large active trapping volume of ~106 nm3 for the target particles. Furthermore, the trapped gold nanoparticles further lead to the formation of nano-gaps that offer a near-field enhancement of ~160 times, resulting in an achievable EF of 108 for SERS. In the third design, we propose a concept of all-optical nano-manipulation. We show that target molecules, after being trapped, can be transferred between the trapping sites within a linear array of PNOTs. The system consists of an array of graded plasmonic nano-disks (NDs) with individual elements coded with different resonant wavelengths according to their dimensions. Thus, by switching the wavelength and rotating the polarization of the excitation source, the target nanoparticles trapped by the device can be manipulated from one ND to another. 3D FDTD simulation and MST calculation are utilized to demonstrate the operation of this idea. Our results reveal that the target experiences a trapping potential strength as high as 5000 kBT/W/microm 2, maximum optical torque of ~336 pN?nm/W/microm2, and the total active volume may reach ~106 nm3. The potential applications in terms of optical sensing are also discussed. In the final design, for which experimental demonstration has been conducted, we show that PNOTs are achievable with random plasmonic nano-islands. Two laser beams having wavelengths of 633 nm and 785 nm are utilized to stimulate the PNOTs and excite the Raman signals simultaneously. The PNOTs are formed by annealing of a thermal evaporated gold film. This so-called nano-island substrate (Au-NIS) has a resonant peak close to 633 nm. The target is photochemical synthesized silver nanodecadedrons (AgNDs) functionalized with 4-Mercaptobenzoic acid (4-MBA) and the resonant peak of these AgNDs is far away from 633 nm and 785 nm. As the target is trapped to the hot-spots when the PNOTs are active, the near-field intensity is enhanced significantly, which results in the emergence of SERS signals, i.e. confirming the expected outcome of SERS upon nanotrapping by the PNOTs. This process is also elucidated numerically through 3D FDTD simulation and MST calculation. Furthermore, the target can be released as the PNOTs become inactive, i.e. disappearance of the SERS signal. Therefore, this design offers not only a robust avenue for monitoring trapping events in PNOTs, but also a reproducible "trap-and-sense" platform for bio-detection. (Abstract shortened by UMI.)

Kang, Zhiwen

375

Simple, benign, aqueous-based amination of polycarbonate surfaces.  

PubMed

Polycarbonate is a desirable material for many applications due to its favorable mechanical and optical properties. Here, we report a simple, safe, environmentally friendly aqueous method that uses diamines to functionalize a polycarbonate surface with amino groups. The use of water as the solvent for the functionalization ensures that solvent induced swelling does not affect the optical or mechanical properties of the polycarbonate. We characterize the efficacy of the surface amination using X-ray photo spectroscopy, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and contact angle measurements. Furthermore, we demonstrate the ability of this facile method to serve as a foundation upon which other functionalities may be attached, including antifouling coatings and oriented membrane proteins. PMID:25695347

VanDelinder, Virginia; Wheeler, David R; Small, Leo J; Brumbach, Michael T; Spoerke, Erik D; Henderson, Ian; Bachand, George D

2015-03-18

376

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

377

Control of surface shear stress by MEMS based transducers  

NASA Astrophysics Data System (ADS)

A micromachined silicon actuator is placed downstream of a stationary vortex generator to investigate the control of the surface shear stress. Polysilicon coil is deposited on a bulk micromachined flap. The AC current passing through the coil induces a time- varying magnetic field to interact with a stationary permanent magnet such that a well-defined oscillatory motion of the flap can be obtained. On the silicon flap, a permalloy layer is electroplated for determining the mean displacement of the actuator. By driving the flap in a proper motion, large surface shear stress reduction can be achieved. Various driving modes of the actuator are examined. The results will be used for designing the adaptive control logic for turbulent shear stress reduction experiment. This work is supported by a AFOSR-URI grant.

Tung, Steve; Ho, Chih-Ming; Jiang, Fukang; Tai, Yu-Chong

1996-11-01

378

Derivation of thermokarst distribution based on climate and surface characteristics  

NASA Astrophysics Data System (ADS)

About one quarter of the northern hemisphere is covered by permafrost. Permafrost areas inherit a high amount of deposited soil organic carbon, which represents approximately 50% of the estimated global below-ground organic carbon pool and is more than twice the size of the current atmospheric carbon pool. A destabilization due to the expected amplitude of future Arctic climate warming would lead to a global-scale feedback mechanism. This feedback comprise interactions between snow, permafrost, hydrology, and ecosystems, which include altered energy and water fluxes between atmosphere and land surface. The representation of permafrost related processes in GCMs and ESMs is still rudimentary and needs to be extended to improve the climate model performance in high latitudes. In this sense thermokarst processes should be included into JSBACH, the land-surface component of MPI-ESM. Initially, a 1-D scheme of thermal dynamics will be implemented into JSBACH, which fits into very recent developments with regards to permafrost melting and freezing (T. Blome; Ekici et al., in prep.) and a dynamical wetland scheme (Stacke and Hagemann, 2012). Structural improvements and new parametrization of the model are required with regard to heat and water flow (physical processes) and carbon and nitrogen dynamics (bio-geochemical processes). The implementation of a thermokarst module is one task within the EU project PAGE21 and is a joint activity between MPI-M Hamburg and MPI-BGC Jena. Thermokarst changes are coupled thermal-hydrological processes, which lead to an enhanced thawing of ice-rich permafrost on local-to-regional scales, where the soil structure is characterized by segregated ice and ice-wedges. They result in severe consequences for soil structure, hydrology, and depletion of soil organic carbon. Thermokarst affected areas appear as a very uneven surface of hummocks and marshy hollows. The initial heat balance of the surface is disturbed by different trigger mechanisms, which cause the ground ice to melt and the soil to subside into depressions due to developing cavities in the interior. The depressions fill up with melting and precipitating water. Since deeper water bodies do not freeze up entirely, the annual mean surface temperature increases in the soil beneath. Therefore permafrost thawing is continued and depressions grow further due to soil subsidence and slope wash at the margins until a new soil surface heat balance is reached. Here I'd like to give a short overview and an introduction into the ongoing thermokarst process in the Arctic tundra. The main focus will be on investigating the actual distribution of thermokarst lakes in the high northern latitudes. The development of thermokarst lakes depends on soil parameters like ice content, surface temperature, soil texture as well as on climate states like monthly mean temperature, precipitation, winter snow depth. They contribute to the surface heat balance and may serve as a measure for thermokarst potential. Since thermokarst mechanism is a small-scale process of 10-1000m in spatial extent, it needs to be parametrized for GCM applications on ESM grid scale. Thus, we want to derive the thermokarst distribution as a function of climate and soil parameters.

Schöngaßner, Thomas; Hagemann, Stefan

2013-04-01

379

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

380

Surface WGM sensor based on a cylindrical dielectric waveguide  

NASA Astrophysics Data System (ADS)

The dispersion equation of a layered cylindrical dielectric waveguide operating in the whispering gallery mode (WGM) is derived. We demonstrate that when the waveguide is coated with a negative permittivity layer, a surface WGM can be generated. It exposes a strong evanescent field to the ambient substance, rendering the negative permittivity material assisted microring sensor much more sensitive to a slight change in surrounding medium. This opens up an avenue towards designing optical WGM sensors with superior performance.

Yang, Jing Jing; Huang, Ming; Zhang Chen, De; Ding, Hong Wei; Mao, Fu Chun

2013-01-01

381

Reconstruction of Two-Dimensional Randomly Rough Surfaces Based on Bidirectional Reflectance Distribution Function  

NASA Astrophysics Data System (ADS)

This article presents an inverse method for reconstructing two-dimensional randomly rough surfaces based on the available (experimental or given) data of the bidirectional reflectance distribution function (BRDF). The Maxwell's equations of electromagnetic waves are applied to describe the light scattering process of rough surfaces by accounting for the near-field effect. Such a forward problem is numerically solved with the finite-difference time-domain algorithm. The inverse scattering problem of reconstructing the surface profile is handled by means of an optimization technique—the particle swarm optimizer algorithm. As an example, reconstruction of a Gaussian rough surface is conducted based on the experimental data of BRDFs. The retrieved results of the surface profile are compared with those measured by atomic force microscopy from the samples, which shows that the reconstruction algorithm can provide the credible prediction of surface profiles. The reconstruction approach studied in this study can make reliable predictions of the actual or required surface profiles.

Xuan, Yimin; Han, Yuge; Zhou, Yue

2013-03-01

382

The Stealth in comparison with other lingual brackets: properties and procedures for indirect bonding.  

PubMed

There are a number of brackets available for lingual orthodontics. One, the Stealth bracket system, which can be positioned in the laboratory with Class or Targ or Pacon bonding systems and can be transferred with multiple or single transfers made either with thermoplastic materials or with resin has some advantages. 1) A single wing with horizontal engagement of the arch and good interbracket distance, permitting early engagement of rectangular arch wire with good torque control. 2) A deep slot and easy ligation that provides good arch wire stability in the slot during friction mechanics without double overties. 3) A thin design that gives little discomfort to the patient, reduces tongue stress and pain during therapy and allows good cleaning of the appliance. 4) A wide mesh with a strong bonding force 5) A horizontal extension on both sides of the slot that provides two points of contact between the slot and the arch wire for rotation control 6) A horizontal slot for insertion of auxiliaries such as a bite plane that can be used when it is clinically indicated. PMID:17364041

Quadrelli, Carlo; Veneziani, Antonio

2007-01-01

383

Production of A357 motor mount bracket by the metal compression forming process  

SciTech Connect

The use of aluminum alloy castings for safety critical structural components such as engine mount brackets, steering knuckles, and control arms, offers significant opportunities for achieving weight reduction in automobiles, since they are typically about half the weight of the steel, cast iron, or ductile iron component that they replace. Metal Compression Forming (MCF) is a variant of the squeeze casting process, in which molten metal is allowed to solidify under pressure in order to close porosity and form a sound part. However, the MCF process applies pressure on the entire mold face, thereby directing pressure on all regions of the casting and producing a uniformly sound part. The process is capable of producing parts with properties close to those of forgings, while retaining the near net shape, complexity in geometry, and relatively low cost of the casting process. The paper describes the casting process development involved in the production of an aluminum A357 alloy motor mount bracket, including the use of a filling and solidification model to design the gating and determine process parameters. Tensile properties of the component are presented and correlated with those of forged components. Limited fatigue properties obtained by fully reversed strain controlled testing are also presented.

Viswanathan, S.; Brinkman, C.R.; Porter, W.D. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Purgert, R.M. [Precision Metal Forming Co., Garfield Heights, OH (United States)

1997-09-01

384

Au Nanostructured Surfaces for Electrochemical and Localized Surface Plasmon Resonance-Based Monitoring of ?-Synuclein-Small Molecule Interactions.  

PubMed

In this proof-of-concept study, the fabrication of novel Au nanostructured indium tin oxide (Au-ITO) surfaces is described for the development of a dual-detection platform with electrochemical and localized surface plasmon resonance (LSPR)-based biosensing capabilities. Nanosphere lithography (NSL) was applied to fabricate Au-ITO surfaces. Oligomers of ?-synuclein (?S) were covalently immobilized to determine the electrochemical and LSPR characteristics of the protein. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed using the redox probe [Fe(CN)6](3-/4-) to detect the binding of Cu(II) ions and (-)-epigallocatechin-3-gallate (EGCG) to ?S on the Au-ITO surface. Electrochemical and LSPR data were complemented by Thioflavin-T (ThT) fluorescence, surface plasmon resonance imaging (SPRi), and transmission electron microscopy (TEM) studies. EGCG was shown to induce the formation of amorphous aggregates that decreased the electrochemical signals. However, the binding of EGCG with ?S increased the LSPR absorption band with a bathochromic shift of 10-15 nm. The binding of Cu(II) to ?S enhanced the DPV peak current intensity. NSL fabricated Au-ITO surfaces provide a promising dual-detection platform to monitor the interaction of small molecules with proteins using electrochemistry and LSPR. PMID:25622115

Cheng, Xin R; Wallace, Gregory Q; Lagugné-Labarthet, François; Kerman, Kagan

2015-02-25

385

Comparative study of friction between metallic and conventional interactive self-ligating brackets in different alignment conditions  

PubMed Central

Objective The aim of this study was to compare the friction between three bracket models: conventional stainless steel (Ovation, Dentsply GAC), self-ligating ceramic (In-Ovation, Denstply GAC) and self-ligating stainless steel brackets (In-Ovation R, Dentsply GAC). Methods Five brackets were used for each model. They were bonded to an aluminum prototype that allowed the simulation of four misalignment situations (n = 10). Three of these situations occurred at the initial phase (in which a 0.016-in nickel-titanium wire was used): 1. horizontal; 2. vertical; and 3. simultaneous horizontal/vertical. One of the situations occurred at the final treatment phase: 4. no misalignment (in which a 0.019 x 0.025-inch stainless steel rectangular wire was used). The wires slipped through the brackets and friction was measured by a Universal Testing Machine. Results Analysis of variance followed by Tukey's Test for multiple comparisons (? = 0.05) were applied to assess the results. Significant interaction (p < 0.01) among groups was found. For the tests that simulated initial alignment, Ovation® bracket produced the highest friction. The two self-ligating models resulted in lower and similar values, except for the horizontal situation, in which In-Ovation C® showed lower friction, which was similar to the In-Ovation R® metallic model. For the no misalignment situation, the same results were observed. Conclusion The self-ligating system was superior to the conventional one due to producing less friction. With regard to the material used for manufacturing the brackets, the In-Ovation C® ceramic model showed less friction than the metallic ones. PMID:25162570

Jakob, Sérgio Ricardo; Matheus, Davison; Jimenez-Pellegrin, Maria Cristina; Turssi, Cecília Pedroso; do Amaral, Flávia Lucisano Botelho

2014-01-01

386

Increased reactivity and in vitro cell response of titanium based implant surfaces after anodic oxidation.  

PubMed

In the quest for improved bone growth and attachment around dental implants, chemical surface modifications are one possibility for future developments. The biological properties of titanium based materials can be further enhanced with methods like anodic polarization to produce an active rather than a passive titanium oxide surface. Here we investigate the formation of hydroxide groups on sand blasted and acid etched titanium and titanium-zirconium alloy surfaces after anodic polarization in an alkaline solution. X-ray photoelectron spectroscopy shows that the activated surfaces had increased reactivity. Furthermore the activated surfaces show up to threefold increase in OH(-) concentration in comparison to the original surface. The surface parameters Sa, Sku, Sdr and Ssk were more closely correlated to time and current density for titanium than for titanium-zirconium. Studies with MC3T3-E1 osteoblastic cells showed that OH(-) activated surfaces increased mRNA levels of osteocalcin and collagen-I. PMID:23912792

Walter, M S; Frank, M J; Sunding, M F; Gómez-Florit, M; Monjo, M; Bucko, M M; Pamula, E; Lyngstadaas, S P; Haugen, H J

2013-12-01

387

Fabrication of superhydrophobic surface from binary micro-/nano-structure of mullite-whisk-based films  

NASA Astrophysics Data System (ADS)

The wettability of solid surface is a very important property of materials, which depends on both surface chemical composition and the geometry of the solid surface. We herein report a simple and inexpensive method to fabricate superhydrophobic surfaces with the use of mullite whisks (MWs) for the first time. Binary micro-/nano-structural surfaces were created by the incorporation of hydrophilic needlelike MWs with poly( ?-methacryloxypropyltrimethoxysilane) to exhibit hydrophobic behavior, which further showed superhydrophobicity with water contact angle of 152.4±2? after modified with stearic acid. The wettability variation from hydrophilicity to hydrophobicity and superhydrophobicity during the assembly process are discussed based on the scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and contact-angle system. The superhydrophobicity of the surface could be attributed to the hierarchical microstructure of the rough surface induced by MWs and low surface energy of stearic acid.

Deng, Zhengyan; Yin, Yongjin; Yang, Shengyang; Wang, Cai-Feng; Chen, Su

2013-11-01

388

Shore-based Photogrammetry of Surface Oil Films  

NASA Astrophysics Data System (ADS)

Naturally occurring oil slicks are commonly visible in coastal waters. These slicks are suitable proxies for fuel oil spills. We took advantage of these naturally occurring slicks by developing a low-cost system to measure these features and monitor their movement. The use of low-cost digital cameras and a mapping program produces georectified animations of surface features, which can then be used to model surface oceanography, including currents and fine-scale processes such as Langmuir cells. A digital SLR camera was mounted on a bridge overlooking Portland Harbor, and it took still images every minute during daylight hours. Images were then averaged over a five minute period in order to reduce small scale variations such as boat traffic and wind waves. These mean images were then normalized to a Z-score, with the range restricted to +/- 2 standard deviations about the mean, and a threshold of approximately the lower third was used to identify slick regions. It then became possible to create a two dimensional histogram showing the probability of a slick occurring at each lat/long pixel by summing matrices over a given period. The histograms could then be constrained to various stages in the tidal cycle (e.g. high or low water), or to specific weather conditions, thus creating an atlas showing the behavior of surface features. This atlas can then be used to improve planning and pre-sighting for oil spill response in both Portland Harbor and further afield. We also found that the algorithm could also be used in other low-cost situations. Because the image is currently set to detect areas that are relatively lighter than surrounding waters, ice in the harbor showed up clearly. A digital SLR system like the one used here could therefore be used to implement a low-cost ice monitoring station. Another potential use is in red tide monitoring, which is currently being developed. Perhaps most usefully, after detecting and highlighting surface features, these highlights can be used in particle image velocimetry to model, track and interpret small scale oceanographic features for considerably lower cost and higher spatial resolutions than the current generation of many remote sensing platforms.

Whitefield, J.; Record, N.; Pershing, A. J.

2010-12-01

389

Chromium boron surfaced nickel-iron base alloys  

NASA Technical Reports Server (NTRS)

Chromium boron diffusion coatings on nickel iron alloys uniquely provide them with improvement in high cycle fatigue strength (up to 30%) and erosion resistance (up to 15 times), compared to uncoated alloy. The diffused chromium layer extends in two essential concentration zones to a total depth of about 40.times.10.sup.-6 m, while the succeeding boron layer is limited to 50-90% of the depth of the richest Cr layer nearest the surface. Both coatings are applied using conventional pack diffusion processes.

Rashid, James M. (Inventor); Friedrich, Leonard A. (Inventor); Freling, Melvin (Inventor)

1984-01-01

390

Physically-based Surface Texture Synthesis Using a Coupled Finite Element System.  

PubMed

This paper describes a stable and robust finite element solver for physically-based texture synthesis over arbitrary manifold surfaces. Our approach solves the reaction-diffusion equation coupled with an anisotropic diffusion equation over surfaces, using a Galerkin based finite element method (FEM). This method avoids distortions and discontinuities often caused by traditional texture mapping techniques, especially for arbitrary manifold surfaces. Several varieties of textures are obtained by selecting different values of control parameters in the governing differential equations, and furthermore enhanced quality textures are generated by fairing out noise in input surface meshes. PMID:21625294

Bajaj, Chandrajit; Zhang, Yongjie; Xu, Guoliang

2008-01-01

391

Fundamental validation for surface texture imaging using a microsphere as a laser-trapping-based microprobe  

NASA Astrophysics Data System (ADS)

A surface imaging technique using a laser-trapped microsphere is proposed. The goal of this research is to image the surface texture, while simultaneously measuring the position of the engineered surfaces using the laser-trapping-based microprobe. This paper presents an investigation of imaging characteristics for the microsphere technique. Depending on the distance from the surface to the microsphere, the available images could be either real or virtual. Virtual images had a higher contrast than real images. Contrast and magnification varies depending on the positions of the focal point of the objective lens and surface.

Michihata, Masaki; Takami, Kosuke; Hayashi, Terutake; Takaya, Yasuhiro

2014-08-01

392

Sub surface damage measurements based on short coherent interferometry  

NASA Astrophysics Data System (ADS)

During the manufacturing process of glass lenses, especially the grinding step, it is important to control such parameters as shape and sub-surface damage (SSD) with high accuracy which essentially influences the duration and costs of the subsequent polishing process. Typically used methods measure the parameters only separately and suffer from limited resolution. Especially, the nondestructive measurement of SSD is a challenge for the metrology of grinded surfaces. In order to detect these parameters simultaneously, the scanning short-coherence interferometer, a method very similar to optical coherence tomography, is setup and tested at Aalen University. The lens under test is mounted on a rotation stage which can be translated in lateral direction. The sensor beam of the interferometer is focused onto the sample and can be moved along the axial direction. The precision of the depth measurements is 0.25 ?m, lateral positioning accuracy is 2 ?m and lateral resolution is 4 ?m. The system is able to measure SSD at several positions on a lens within 10 min inside the optical workshop.

Sergeeva, M.; Khrenikov, K.; Hellmuth, T.; Boerret, R.

2010-01-01

393

A silicon-based surface code quantum computer  

E-print Network

Individual impurity atoms in silicon can make superb individual qubits, but it remains an immense challenge to build a multi-qubit processor: There is a basic conflict between nanometre separation desired for qubit-qubit interactions, and the much larger scales that would enable control and addressing in a manufacturable and fault tolerant architecture. Here we resolve this conflict by establishing the feasibility of surface code quantum computing using solid state spins, or `data qubits', that are widely separated from one another. We employ a second set of `probe' spins which are mechanically separate from the data qubits and move in-and-out of their proximity. The spin dipole-dipole interactions give rise to phase shifts; measuring a probe's total phase reveals the collective parity of the data qubits along the probe's path. We introduce a protocol to balance the systematic errors due to the spins being imperfectly located during device fabrication. Detailed simulations show that the surface code's threshold then corresponds to misalignments that are substantial on the scale of the array, indicating that it is very robust. We conclude that this simple `orbital probe' architecture overcomes many of the difficulties facing solid state quantum computing, while minimising the complexity and offering qubit densities that are several orders of magnitude greater than other systems.

Joe O'Gorman; Naomi H. Nickerson; Philipp Ross; John J. L. Morton; Simon C. Benjamin

2014-10-07

394

Reflectance-Based Sensor Validation Over Ice Surfaces  

NASA Technical Reports Server (NTRS)

During this period work was performed in the following areas. These areas are defined in the Work Schedule presented in the original proposal: BRDF development, Data acquisition and processing, THR Table generation and Presentations and Publications. BRDF development involves creating and/or modifying a reflectance model of the Antarctic surface. This model must, for a temporal and spatial average, be representative of the East Antarctic plateau and be expressed in terms of the three standard surface angles: solar zenith angle (SolZA), view zenith angle (SatZA), and relative azimuth angle (RelAZ). We successfully acquired a limited amount of NOAA-9 AVHRR data for radiance validation. The data were obtained from the Laboratory for Terrestrial Physics at Goddard Space Flight Center. We developed our own reading and unpacking software, which we used to select Channel 1 data (visible). We then applied geographic subsetting criteria (same as used for TOMS), and wrote only the relevant data to packed binary files. We proceeded with analysis of these data, which is not yet complete.

Jaross, Glen; Dodge, James C. (Technical Monitor)

2003-01-01

395

Efficient Antifouling Surface for Quantitative Surface Plasmon Resonance Based Biosensor Analysis  

PubMed Central

Non-specific binding to biosensor surfaces is a major obstacle to quantitative analysis of selective retention of analytes at immobilized target molecules. Although a range of chemical antifouling monolayers has been developed to address this problem, many macromolecular interactions still remain refractive to analysis due to the prevalent high degree of non-specific binding. In this manuscript we explore the dynamic process of the formation of self-assembled monolayers and optimize physical and chemical properties thus reducing considerably non-specific binding while maintaining the integrity of the immobilized biomolecules. As a result, analysis of specific binding of analytes to immobilized target molecules is significantly facilitated. PMID:22984487

Nogues, Claude; Leh, Hervé; Lautru, Joseph; Delelis, Olivier; Buckle, Malcolm

2012-01-01

396

Hierarchical construction of stratigraphic elements in surface-based reservoir models  

NASA Astrophysics Data System (ADS)

We present a surface-based simulation algorithm connecting stratigraphic hierarchy with surface-based reservoir models through statistical metrics. Geostatistical simulation algorithms provide tools for modeling spatial complexity and the resulting uncertainties for energy resource assessments. As a new family within a wide array of stochastic geological models, surface-based models and rule-based algorithms effectively represent stratigraphic responses to geological events in both time and space by assigning depositional and erosional surfaces with predefined geometries and rules. Recent advances in surface-based modeling focus on simulating morphological evolution of deep-water depositional systems and constraining models to available well and seismic data. However, especially in deep-water plays, scarce well data can only bring information about local stratal features rather than relatively general information such as hierarchy or organization, when these features are below seismic resolution. Without such information, surface-based models lack geological realism and may not be reliable even when conditioned to data. Our proposed surface-based simulation algorithm links stratigraphic hierarchy with surface-based reservoir modeling through spatial statistical tools. Ripley's K-function is used to quantitatively describe the stratigraphic distribution patterns of channel deposits. We also use the compensation index metric for quantifying the strength of compensational stacking in stratigraphic elements. These two metrics help us to extract information about sedimentary hierarchy and element organization from a set of experimental strata, and bridge physical tank experiments with numerical models. We utilize these two geostatistical metrics in conjunction with a surface-based simulation algorithm to 1) integrate clustering and compensational stacking patterns of channel deposits into reservoir modeling 2) make numerical models represent a stratigraphic hierarchical framework comparable to physical tank experiments 3) explore a means of imparting stochastic structures to models and improving geological realism. These models can be used to better assess subsurface spatial uncertainty.

Wang, Y.; Xu, S.; Mukerji, T.

2013-12-01

397

Simulation of a Lunar Surface Base Power Distribution Network for the Constellation Lunar Surface Systems  

NASA Technical Reports Server (NTRS)

The Lunar Surface Power Distribution Network Study team worked to define, breadboard, build and test an electrical power distribution system consistent with NASA's goal of providing electrical power to sustain life and power equipment used to explore the lunar surface. A testbed was set up to simulate the connection of different power sources and loads together to form a mini-grid and gain an understanding of how the power systems would interact. Within the power distribution scheme, each power source contributes to the grid in an independent manner without communication among the power sources and without a master-slave scenario. The grid consisted of four separate power sources and the accompanying power conditioning equipment. Overall system design and testing was performed. The tests were performed to observe the output and interaction of the different power sources as some sources are added and others are removed from the grid connection. The loads on the system were also varied from no load to maximum load to observe the power source interactions.

Mintz, Toby; Maslowski, Edward A.; Colozza, Anthony; McFarland, Willard; Prokopius, Kevin P.; George, Patrick J.; Hussey, Sam W.

2010-01-01

398

A Fast Terahertz Spectrometer Based on Frequency Selective Surface Filters  

NASA Astrophysics Data System (ADS)

We present a fast spectrometer working in the 0.7-4.8 THz range. Broadband radiation from a blackbody source is focused first on a rotating silicon wafer, whose surface was patterned with 18 metal band-pass filters, then on the sample under test and finally is detected by a superconducting microbolometer with microsecond time constant. The bolometer sensor is coupled to a spiral antenna whose frequency band matches the spectral range of the filters. The spectral resolution is set by the filters quality factor of about 3. A dynamic range of 100 and a S/N ratio of 20 are achieved by integrating for less than 10 second. The detector can operate up to 6 K in a closed-cycle cooler, hence making the present apparatus suitable for building up a simple terahertz video-rate spectrometer.

Carelli, P.; Chiarello, F.; Cibella, S.; Di Gaspare, A.; Leoni, R.; Ortolani, M.; Torrioli, G.

2012-05-01

399

Nanoparticle array based optical frequency selective surfaces: theory and design.  

PubMed

We demonstrate a synthesis procedure for designing a bandstop optical frequency selective surface (FSS) composed of nanoparticle (NP) elements. The proposed FSS uses two-dimensional (2-D) periodic arrays of NPs with subwavelength unit-cell dimensions. We derive equivalent circuit for a nanoparticle array (NPA) using the closed-form solution for a 2-D NPA excited by a plane wave in the limit of the dipole approximation, which includes contribution from both individual and collective plasmon modes. Using the extracted equivalent circuit, we demonstrate synthesis of an optical FSS using cascaded NPA layers as coupled resonators, which we validate with both circuit model and full-wave simulation for a third-order Butterworth bandstop prototype. PMID:23842402

Saeidi, Chiya; van der Weide, Daniel

2013-07-01

400

Laser-based structural sensing and surface damage detection  

NASA Astrophysics Data System (ADS)

Damage due to age or accumulated damage from hazards on existing structures poses a worldwide problem. In order to evaluate the current status of aging, deteriorating and damaged structures, it is vital to accurately assess the present conditions. It is possible to capture the in situ condition of structures by using laser scanners that create dense three-dimensional point clouds. This research investigates the use of high resolution three-dimensional terrestrial laser scanners with image capturing abilities as tools to capture geometric range data of complex scenes for structural engineering applications. Laser scanning technology is continuously improving, with commonly available scanners now capturing over 1,000,000 texture-mapped points per second with an accuracy of ~2 mm. However, automatically extracting meaningful information from point clouds remains a challenge, and the current state-of-the-art requires significant user interaction. The first objective of this research is to use widely accepted point cloud processing steps such as registration, feature extraction, segmentation, surface fitting and object detection to divide laser scanner data into meaningful object clusters and then apply several damage detection methods to these clusters. This required establishing a process for extracting important information from raw laser-scanned data sets such as the location, orientation and size of objects in a scanned region, and location of damaged regions on a structure. For this purpose, first a methodology for processing range data to identify objects in a scene is presented and then, once the objects from model library are correctly detected and fitted into the captured point cloud, these fitted objects are compared with the as-is point cloud of the investigated object to locate defects on the structure. The algorithms are demonstrated on synthetic scenes and validated on range data collected from test specimens and test-bed bridges. The second objective of this research is to combine useful information extracted from laser scanner data with color information, which provides information in the fourth dimension that enables detection of damage types such as cracks, corrosion, and related surface defects that are generally difficult to detect using only laser scanner data; moreover, the color information also helps to track volumetric changes on structures such as spalling. Although using images with varying resolution to detect cracks is an extensively researched topic, damage detection using laser scanners with and without color images is a new research area that holds many opportunities for enhancing the current practice of visual inspections. The aim is to combine the best features of laser scans and images to create an automatic and effective surface damage detection method, which will reduce the need for skilled labor during visual inspections and allow automatic documentation of related information. This work enables developing surface damage detection strategies that integrate existing condition rating criteria for a wide range damage types that are collected under three main categories: small deformations already existing on the structure (cracks); damage types that induce larger deformations, but where the initial topology of the structure has not changed appreciably (e.g., bent members); and large deformations where localized changes in the topology of the structure have occurred (e.g., rupture, discontinuities and spalling). The effectiveness of the developed damage detection algorithms are validated by comparing the detection results with the measurements taken from test specimens and test-bed bridges.

Guldur, Burcu

401

Spatially nonreciprocal Bragg gratings based on surface plasmons  

NASA Astrophysics Data System (ADS)

Using the concept of parity-time symmetry in optics, we propose a spatially non-reciprocal Bragg grating at near infrared wavelengths, operating with long-range surface plasmon polaritons, by employing balanced modulation of index and gain/loss in a step-in-width configuration. The index perturbation is created by stepping the width of an Ag stripe supporting long-range plasmons. Gain/loss modulation is generated by periodically doping the top polymer cladding of the structure with IR-140 dye molecules and pumping the grating optically from top. Loss exists inherently in the undoped regions due to plasmonic propagation loss. The transmission matrix method was employed as an accurate modeling technique to compute the reflectance and transmittance spectra of the proposed structures. Simulation results exhibit a strong reflectance from one end of the grating at about 880 nm as opposed to nearly no reflectance from the other end at the same wavelength.

Keshmarzi, Elham Karami; Tait, R. Niall; Berini, Pierre

2014-11-01

402

Multilayer magnetostrictive structure based surface acoustic wave devices  

NASA Astrophysics Data System (ADS)

This study addresses the experimental and theoretical investigations of guided elastic waves propagation in piezo-magnetic multi-layered structure. The structure is composed of a 20×TbCo2(5nm)/FeCo(5nm) nanostructured multi-layer deposited between two Aluminum (Al) Inter-Digitals Transducers forming a surface acoustic wave delay line, on a Y-cut LiNbO3 substrate. We compare the calculated and measured phase velocity variation under the action of the external magnetic field orientation and magnitude. We find quantitative agreement between the measured and modeled phase velocity shift for all external magnetic field configurations (hard axis and easy axis) and for different shape modes of elastic waves at their first and third harmonic operation frequencies. The shear horizontal mode exhibits a maximum phase velocity shift close to 20% for a ratio close to 1 between magneto-elastic film thickness and wavelength.

Zhou, H.; Talbi, A.; Tiercelin, N.; Bou Matar, O.

2014-03-01

403

The localized surface plasmon resonances based on a Bragg reflector  

NASA Astrophysics Data System (ADS)

In this paper, we present the theoretical analysis on how the wavelength of the localized surface plasmon resonances of gold nanoparticle can lead shift for the resonance wavelength. In our results, we calculate the scattering cross-section, the absorption cross-section and the field enhancement due to the nanoparticle. Numerical simulation were done using the finite element method (FEM). The work that we do here is different from the previous work because we use the Bragg reflector as a substrate. The Bragg reflector has a property of high reflectivity in some certain frequency bandwidth because of its periodic structure. The coherence interference of the Bragg reflector contributes to the plasmon resonances and results in some special character for a wide variety application, from sensing to photovoltaic. The periodic number of the Bragg reflector substrate and shapes of the nanoparticles are also discussed that result in a shift of the resonance wavelength.

Wang, Jie; Liu, Yumin; Yu, Zhongyuan; Ye, Chunwei; Lv, Hongbo; Shu, Changgan

2014-09-01

404

Optofluidic FRET microlasers based on surface-supported liquid microdroplets  

NASA Astrophysics Data System (ADS)

We demonstrate optofluidic microlasers using highly efficient non-radiative Förster resonance energy transfer (FRET) for pumping of gain medium placed within liquid microdroplets situated on a superhydrophobic surface. Microdroplets generated from a mixture of ethylene glycol, glycerol, and water and stained with the FRET donor–acceptor dye pair Rhodamine 6G-Rhodamine 700 serve as active optical resonant cavities hosting high-quality whispering gallery modes. Upon direct optical pumping of the donor with a pulsed laser, lasing is observed in the emission band of the acceptor as a result of efficient FRET coupling between the acceptor and donor molecules. FRET lasing is characterized for different acceptor and donor concentrations, and threshold pump fluences of acceptor lasing as low as 6.3 mJ cm?2 are demonstrated. We also verify the dominance of the non-radiative FRET over cavity-assisted radiative energy transfer for the range of parameters studied in the experiments.

Özelci, E.; Aas, M.; Jonáš, A.; Kiraz, A.

2014-04-01

405

Speaker-Adaptive Speech Recognition Based on Surface Electromyography  

NASA Astrophysics Data System (ADS)

We present our recent advances in silent speech interfaces using electromyographic signals that capture the movements of the human articulatory muscles at the skin surface for recognizing continuously spoken speech. Previous systems were limited to speaker- and session-dependent recognition tasks on small amounts of training and test data. In this article we present speaker-independent and speaker-adaptive training methods which allow us to use a large corpus of data from many speakers to train acoustic models more reliably. We use the speaker-dependent system as baseline, carefully tuning the data preprocessing and acoustic modeling. Then on our corpus we compare the performance of speaker-dependent and speaker-independent acoustic models and carry out model adaptation experiments.

Wand, Michael; Schultz, Tanja

406

Surface, Interfacial and Tribological Properties of Cereal-based Amphiphiles  

Technology Transfer Automated Retrieval System (TEKTRAN)

Starch, protein and oil are the major components of most cereals such as corn and soybean. These components, with or without further chemical modification, display a number of important amphiphilic characteristics that are of interest in a number of applications. Cereal-based oils have polar compo...

407

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. PMID:23066253

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

2012-01-01

408

Excitation of surface electromagnetic waves in a graphene-based Bragg grating  

PubMed Central

Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc. PMID:23071901

Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting

2012-01-01

409

Surface acid-base properties and hydration/dehydration mechanisms of aluminum (hydr)oxides.  

PubMed

In this paper, surface physiochemical properties of three typical aluminas, gamma-Al(OH)3, gamma-Al2O3, and alpha-Al2O3, were investigated by means of XRD, SEM, TEM, BET surface area, TG/DTA, and potentiometric titration techniques. Based on the titration data, surface protonation and deprotonation constants were determined using the constant capacitance model (CCM). The emphasis of this research was laid on the comparison of the crystal structure, surface hydration/dehydration and acid-base properties of these three typical alumina minerals. The calculation results revealed that the surface acidity of the aluminas is in the order of alpha-Al2O3>gamma-Al(OH)3>gamma-Al2O3 after being hydrated for 1 h. The correlation between the hydration/dehydration mechanisms of alumina and its acid/base properties is discussed. PMID:17275018

Yang, Xiaofang; Sun, Zhongxi; Wang, Dongsheng; Forsling, Willis

2007-04-15

410

Dynamic surface control-backstepping based impedance control for 5DOF flexible joint robots  

Microsoft Academic Search

A new impedance controller based on the dynamic surface control-backstepping technique to actualize the anticipant dynamic\\u000a relationship between the motion of end-effector and the external torques was presented. Comparing with the traditional backstepping\\u000a method that has “explosion of terms” problem, the new proposed control system is a combination of the dynamic surface control\\u000a technique and the backstepping. The dynamic surface

Gen-liang Xiong; Zong-wu Xie; Jian-bin Huang; Hong Liu; Zai-nan Jiang; Kui Sun

2010-01-01

411

Enhanced output power in GaN-based LEDs with naturally textured surface grown by MOCVD  

Microsoft Academic Search

GaN-based light-emitting diodes (LEDs) with naturally textured surfaces grown by MOCVD were demonstrated. In this study, a growth-interruption step and a surface treatment using biscyclopentadienyl magnesium (CP2Mg) were simultaneously performed to form a plurality of nuclei sites on the surface of a p-type cladding layer, and then a p-type contact layer was grown on the p-type cladding layer, so as

C. M. Tsai; J. K. Sheu; W. C. Lai; Y. P. Hsu; P. T. Wang; C. T. Kuo; C. W. Kuo; S. J. Chang; Y. K. Su

2005-01-01

412

Surface damage in ZrB 2 -based composite ceramics induced by electro-discharge machining  

Microsoft Academic Search

Electro-conductive ZrB2-based composite ceramics, containing SiC and B4C, were machined with an electro-discharge machining (EDM) process. The EDMed surfaces were covered with resolidified ZrB2 layers. Many open pores and surface cracks were observed on the surfaces. The strength degradation of the ceramics caused by machining was evaluated by three point bending tests of the partially EDMed bending specimens. The effects

M. Nakamura; I. Shigematsu; K. Kanayama; Y. Hirai

1991-01-01

413

Moving Surface Spline Interpolation Based on Green’s Function  

Microsoft Academic Search

Some commonly used interpolation algorithms are analyzed briefly in this paper. Among all of the methods, biharmonic spline\\u000a interpolation, which is based on Green’s function and proposed by Sandwell, has become the mainstream method for its high\\u000a precision, simplicity and flexibility. However, the minimum curvature method has two flaws. First, it suffers from undesirable\\u000a oscillations between data points, which is

Xingsheng Deng; Zhong-an Tang

2011-01-01

414

Evaluation of a photosyntheses-based canopy resistance formulation in the Noah Land-surface model  

Technology Transfer Automated Retrieval System (TEKTRAN)

Accurately representing complex land-surface processes balancing complexity and realism remains one challenge that the weather modelling community is facing nowadays. In this study, a photosynthesis-based Gas-exchange Evapotranspiration Model (GEM) is integrated into the Noah land-surface model repl...

415

Space-based detection of wetlands' surface water level changes from L-band SAR interferometry  

E-print Network

Space-based detection of wetlands' surface water level changes from L-band SAR interferometry­1996 reveals detectable surface changes in the Everglades wetlands. Although our study is limited to south Florida it has implication for other large-scale wetlands, because south Florida wetlands have diverse

Amelung, Falk

416

A theoretical analysis of FGM thin plates based on physical neutral surface  

Microsoft Academic Search

This paper presents a theoretical analysis to the FGM (functionally graded materials) thin plates based on the physical neutral surface. Under the assumption of changeable parameters such as the Young’s modulus E and the mass density ? along the thickness of the plate, the physical neutral surface of a FGM plate is determined by the theory of thin plate when

Da-Guang Zhang; You-He Zhou

2008-01-01

417

Satellite-based observations of surface turbulent stress during severe weather  

E-print Network

Satellite-based observations of surface turbulent stress during severe weather Mark A. Bourassa and a vertical offset (i.e., displacement height) of the log-wind profile, due to wave modification The environment of severe marine weather is harsh: in situ and satellite observations of surface turbulent

418

3D MHD Free Surface Fluid Flow Simulation Based on Magnetic-Field Induction Equations  

E-print Network

1 3D MHD Free Surface Fluid Flow Simulation Based on Magnetic-Field Induction Equations H.L. HUANG, a penalty factor is introduced in order to force the local divergence free condition of the magnetic fields boundaries is null. These simulation results for lithium film free surface flows under NSTX outboard mid

California at Los Angeles, University of

419

3D MHD free surface fluid flow simulation based on magnetic-field induction equations  

E-print Network

3D MHD free surface fluid flow simulation based on magnetic-field induction equations H.L. Huang 1 in order to force the local divergence free condition of the magnetic fields. The second is that we extend. These simulation results for lithium film free surface flows under NSTX outboard mid-plane magnetic field

Abdou, Mohamed

420

Triangle Mesh-Based Surface Modeling Using Adaptive Smoothing and Implicit Texture Integration  

E-print Network

Triangle Mesh-Based Surface Modeling Using Adaptive Smoothing and Implicit Texture Integration Y a framework of surface model- ing from multi-view range data. The input to the al- gorithms are triangle meshes, each of which is from a single view range scan. The triangle meshes gener- ated from raw data

Koschan, Andreas

421

Reconfigurable Artificial Surfaces Based on Impedance Loaded Wires Close to a Ground Plane  

Microsoft Academic Search

This contribution investigates artificial surfaces based on arrays of impedance loaded wires in the proximity of a ground plane. It is found that for specific loads it is possible to realize high impedance surfaces and absorbing boundaries with very low profile. Furthermore, it is demonstrated that such loads correspond with realistic values which can be implemented with lumped elements and\\/or

Iñigo Liberal; Igor S. Nefedov; Iñigo Ederra; Ramón Gonzalo; Sergei A. Tretyakov

2012-01-01

422

A model-based four-dimensional left ventricular surface detector  

Microsoft Academic Search

The authors have developed a general model-based surface detector for finding the four-dimensional (three spatial dimensions plus time) endocardial and epicardial left ventricular boundaries. The model encoded left ventricular (LV) shape, smoothness, and connectivity into the compatibility coefficients of a relaxation labeling algorithm. This surface detection method was applied to gated single photon emission computed tomography (SPECT) perfusion images, tomographic

Tracy L. Faber; Ernest M. Stokely; Ronald M. Peshock; James R. Corbett

1991-01-01

423

Mapping surface soil moisture using an aircraft-based passive microwave instrument: algorithm and example  

Microsoft Academic Search

Microwave remote sensing at L-band (21 cm wavelength) can provide a direct measurement of the surface soil moisture for a range of cover conditions and within reasonable error bounds. Surface soil moisture observations are rare and, therefore, the use of these data in hydrology and other disciplines has not been fully explored or developed. Without satellite-based observing systems, the only

T. J. Jackson; David E. Le Vine

1996-01-01

424

Construction of intermediate section profiles of a blade, based on initial profiles predetermined on conical surfaces  

Microsoft Academic Search

The authors describe how to obtain blade profiles of an axial turbine perpendicular to the radial direction and used for producing a working drawing of the blade based on initial profiles designed for the purpose of reducing the energy losses in an annular cascade on conical surfaces approximating the axisymmetrical surfaces of the flow of the working medium.

M. P. Kaplan; N. N. Kovalenko

1983-01-01

425

High Light-Extraction GaN-Based Vertical LEDs With Double Diffuse Surfaces  

Microsoft Academic Search

High light -extraction (external quantum efficiency ~40%) 465 -nm GaN -based vertical light -emitting diodes (LEDs) employing double diffuse surfaces were fabricated. The high scattering efficiency of double diffused surfaces could be responsible for the high light output power. ©2006 Optical Society of America OCIS codes: (230. 3670 )

Ya-Ju Lee; Hao-Chung Kuo; Tien-Chang Lu; Shing-Chung Wang

2006-01-01

426

Theory and experiment of novel frequency selective surface based on substrate integrated waveguide technology  

Microsoft Academic Search

A novel frequency selective surface (FSS) based on substrate integrated waveguide (SIW) technology is investigated with simulation and experiment. The periodic unit is made of a SIW cavity with slots on the top and bottom surfaces, and the whole FSS is fabricated on a microwave substrate with standard PCB process. The high-Q property of SIW cavities greatly improved the frequency

Guo Qing Luo; Wei Hong; Zhang-Cheng Hao; Bing Liu; Wei Dong Li; Ji Xin Chen; Hou Xing Zhou; K. Wu

2005-01-01

427

Predictions on surface finish in electrical discharge machining based upon neural network models  

Microsoft Academic Search

Predictions on the surface finish of work-pieces in electrical discharge machining (EDM)