These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

2

Tensile bond strength of metal bracket bonding to glazed ceramic surfaces with different surface conditionings  

PubMed Central

Objective The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. Materials and Methods Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primer and adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively. Results The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01). Conclusion In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength. PMID:22509459

Akhoundi, MS. Ahmad; Kamel, M. Rahmati; Hashemi, SH. Mahmood; Imani, M.

2011-01-01

3

Heat treatment following surface silanization in rebonded tribochemical silica-coated ceramic brackets: shear bond strength analysis  

PubMed Central

Objective This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets. Material and Methods Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20): Gc, no treatment (control); Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s). Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC) (TC). The specimens were submitted to the shear bond strength (SBS) test using a universal testing machine (1 mm/min). Failure mode was assessed using optical and scanning electron microscopy (SEM), together with the surface roughness (Ra) of the resin cement in the bracket using interference microscopy (IM). 2-way ANOVA and the Tukey test were used to compare the data (p>0.05). Results The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0), but thermocycling did not (p=0.6974). Considering the SBS results (MPa), Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9) and Gt-TC showed the lowest (8.45±6.7). For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157) but the surface treatments did not (p=0.458). For the thermocycled and non-thermocycled groups, Ra (µm) was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces. Conclusion Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are a more effective strategy. PMID:24037072

SILVA, Emilia Adriane; TRINDADE, Flávia Zardo; RESKALLA, Hélcio Nagib José Feres; de QUEIROZ, José Renato Cavalcanti

2013-01-01

4

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

5

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

6

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

PubMed Central

Objective: This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. Materials and Methods: The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively), an ultrafine diamond bur (group 3) or an Er:YAG laser (250 mJ, long pulse, 4 Hz) (group 4), and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed. Results: The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05). Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01). In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05). Conclusion: Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets. PMID:23724206

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

2013-01-01

7

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

8

Tiedown Bracket  

NASA Technical Reports Server (NTRS)

Tiedown bracket secured to concrete slab with lag anchor and lag bolt. A trailer or other heavy equipment can be anchored by tethering it to strapping bolt. When bracket is no longer needed, it can be removed, leaving behind only lag anchor. Bracket is easily installed and removed without damage to concrete slab.

Mashburn, D.; Wald, J. E.; Helmsin, F. K.

1982-01-01

9

Temperature analysis during bonding of brackets using LED or halogen light base units.  

PubMed

The purpose of our investigation is to compare the intrapulpal temperature changes following blue LED system and halogen lamp irradiation at the enamel surface of permanent teeth. The fixation of brackets using composite resin is more comfortable and faster when using a photo-curable composite. Several light sources can be used: halogens, arc plasma, lasers, and recently blue LED systems. An important aspect to be observed during such a procedures is the temperature change. In this study, we have used nine human extracted permanent teeth: three central incisors, three lateral incisors, and three canines. Teeth were exposed to two light sources: blue LED system (preliminary commercial model LEC 470-II) and halogen lamp (conventional photo-cure equipment). The surface of teeth was exposed for 20, 40, and 60 sec at the buccal and lingual enamel surface with an angle of 45 degrees. Temperature values measured by a thermistor placed at pulpar chamber were read in time intervals of 1 sec. We obtained plots showing the temperature evolution as a function of time for each experiment. There is a correlation between heating quantity and exposition time of light source: with increasing exposition time, heating increases into the pulpal chamber. The halogen lamp showed higher heating than the LED system, which showed a shorter time of cooling than halogen lamp. The blue LED system seems like the indicated light source for photo-cure of composite resin during the bonding of brackets. The fixation of brackets using composite resin is more comfortable and faster when using a photo-curable composite. Blue LED equipment did not heat during its use. This could permit a shorter clinical time of operation and better performance. PMID:15782031

Silva, Paulo César Gomes; De Fátima Zanirato Lizarelli, Rosane; Moriyama, Lílian Tan; De Toledo Porto Neto, Sizenando; Bagnato, Vanderlei Salvador

2005-02-01

10

Laser radiation bracket debonding  

NASA Astrophysics Data System (ADS)

Ceramic brackets are an aesthetic substitute for conventional stainless steel brackets in orthodontic patients. However, ceramic brackets are more brittle and have higher bond strengths, which can lead to bracket breakage and enamel damage during classical type of debonding. This study examined the possibility of laser radiation ceramic brackets removing as well as the possible damage of a surface structure of hard dental tissue after this procedure. Two types of lasers were used for the experiments - a laser diode LIMO HLU20F400 generating a wavelength of 808 nm with the maximum output power 20W at the end of the fiber (core diameter 400 ?m, numerical aperture 0.22). As a second source, a diode-pumped Tm:YAP laser system generating a wavelength of 1.9 ?m, with up to 3.8 W maximum output power was chosen. For the investigation, extracted incisors with ceramic brackets were used. In both cases, laser radiation was applied for 0.5 minute at a maximum power of 1 W. Temperature changes of the irradiated tissue was registered by camera Electrophysics PV320. After the interaction experiment, the photo-documentation was prepared by the stereomicroscope Nikon SMZ 2T, Japan. The surface tissue analysis was processed in "low vacuum" (30 Pa) regime without desiccation. This technique was used to record back-scattered electron images. Selecting the appropriate laser, resin, and bracket combination can minimize risks of enamel degradation and make debonding more safe.

Dostálová, Tat'jana; Jelínková, Helena; Šulc, Jan; Koranda, Petr; Nemec, Michal; Racek, Jaroslav; Miyagi, Mitsunobu

2008-02-01

11

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

12

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

13

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

PubMed Central

Objectives: Satisfactory bonding of orthodontic attachments to amalgam is a challenge for orthodontists. The aim of this in vitro study was to compare the shear bond strength of stainless steel orthodontic brackets to silver amalgam treated with sandblasting and Er,Cr:YSGG laser. Study Design: Fifty-four amalgam discs were prepared, polished and divided into three groups: In group 1 (the control group) the premolar brackets were bonded using Panavia F resin cement without any surface treatment; in groups 2 and 3, the specimens were subjected to sandblasting and Er,Cr:YSGG laser respectively, before bracket bonding. After immersing in distilled water at 37°C for 24 hours, all the specimens were tested for shear bond strength. Bond failure sites were evaluated under a stereomicroscope. Data was analyzed using one-way ANOVA and a post hoc Tukey test. Results: The highest and lowest shear bond strength values were recorded in the laser and control groups, respectively. There were significant differences in mean shear bond strength values between the laser and the other two groups (p<0.05). However, there were no significant differences between the sandblast and control groups (p=0.5). Conclusions: Amalgam surface treatment with Er,Cr:YSGG laser increased shear bond strength of stainless steel orthodontic brackets. Key words: Amalgam, surface treatment, shear bond strength, sandblasting, Er,Cr:YSGG laser. PMID:22143706

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

2012-01-01

14

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

15

On Derivation of Goldman Bracket  

E-print Network

In this paper, we derive Goldman-type bracket for traces of monodromy matrices of flat connections on a compact Riemann surface for $G_{2}$ gauge group. As a by-product, we give an alternative derivation of known Goldman bracket for classical gauge groups $GL(n,\\mathbb{R})$, $SL(n,\\mathbb{R})$, $U(n)$, $SU(n)$, $Sp(2n,\\mathbb{R})$ and $SO(n)$.

S. Hasibul Hassan Chowdhury

2013-10-16

16

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

17

On Derivation of Goldman Bracket  

E-print Network

Non abelian Gauge field theory on space-time, modeled as a noncompact 3-manifold $\\Sigma\\times\\mathbb{R}$, with $\\Sigma$ being a compact Riemann surface and time taking values in $\\mathbb{R}$, has been considered. The Atiyah-Bott brackets between the gauge fields have been computed in this infinite dimensional setting. Traces of monodromies of the gauge connections around free homotopy classes of closed loops on the underlying Riemann surface and the Poisson brackets between them are computed using the formalism originated from hamiltonian methods of Soliton theory. Finally, the brackets for real Lie groups $GL(n,\\mathbb{R})$, $SL(n,\\mathbb{R})$, U(n), SU(n) and $Sp(2n,\\mathbb{R})$ are explicitly worked out.

Chowdhury, S Hasibul Hassan

2013-01-01

18

Universal Cable Brackets  

NASA Technical Reports Server (NTRS)

Concept allows routing easily changed. No custom hardware required in concept. Instead, standard brackets cut to length and installed at selected locations along cable route. If cable route is changed, brackets simply moved to new locations. Concept for "universal" cable brackets make it easy to route electrical cable around and through virtually any structure.

Vanvalkenburgh, C.

1985-01-01

19

BRACKETING RESIDENTIAL \\  

Microsoft Academic Search

A net-zero residence is highly dependent on the life- style of the occupants, building construction, equipment operation and maintenance, and the weather conditions. With increasing interest in net-zero energy consumption, it is important to base any claim for the \\

Rohini Brahme; Gregory Dobbs; Thierry Carriere

20

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

21

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

22

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

23

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

24

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

25

[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

26

A tensomeric and planimetric evaluation of the durability of the bond between an orthodontic bracket and enamel.  

PubMed

The development of orthodontics has improved thanks to the introduction of adhesives which are physically and chemically akin to tooth enamel and brackets. These materials often fall short of the required durability standards. The objective was to evaluate the real strength of the adhesives and to introduce a proprietary device, generating multiple vectors of strength between dental brackets and the surface of enamel. 11 types of adhesive materials have been studied. 990 applications have been made using removed teeth, followed by a randomised creation of 11 groups containing 90 samples each. The threshold values of the strength needed to break the brackets off were determined in torsional, shear and tension strength tests. A comparison between tensometric and planimetric methods was made by means based on ARI index. Resistance was highest for torsional stress, weaker for shear stress and the weakest for tension stress. A correlation was found between tensometric results. The study attempted to systematise the methodology of direct tests. PMID:24479646

Pawlus, Bart?omiej; Dyszkiewicz, Andrzej; Spidlen, Miloš

2013-01-01

27

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

28

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

29

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

30

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

31

Bond strengths of ceramic brackets using different bonding techniques.  

PubMed

A series of laboratory investigations was carried out to compare the shear-type bond strengths and site of bond failure of ceramic orthodontic brackets bonded to etched enamel. When light-cured composite resin was used as the luting agent, there was no reduction in bond strength when using 2.5 per cent nitric acid to etch the enamel, compared to 37 per cent phosphoric acid. The use of the two resin modified glass ionomer cements were found to give rise to significantly lower bond strengths than composite resin when used for placing ceramic brackets. Significantly less composite resin remained on the enamel surface following bracket removal in those samples etched with nitric acid. PMID:7786864

Blight, S J; Lynch, E

1995-02-01

32

Trial production of titanium orthodontic brackets fabricated by metal injection molding (MIM) with sintering.  

PubMed

Safety and esthetics are two indispensable factors to consider when fabricating orthodontic brackets. However, these factors are not easily achieved when conventional techniques (including forging and casting) are used in the mass production of titanium brackets, albeit the brackets exhibit excellent biocompatibility. In the present study, orthodontic brackets were manufactured by metal powder injection molding with sintering. Brackets with three different base designs were made and subjected to compression shear tests for evaluation of their bonding strength to enamel substrate. The shapes given to the dimple of the base were spherical, oval, and grooved. The maximum shear forces for each type were 11.1 kgf, 7.6 kgf, and 18.5 kgf, respectively. The bonding strengths of the titanium bracket were equivalent to those obtained with conventional stainless steel brackets. Moreover, uniform distribution of Vickers hardness values (average, 240 +/- 40 Hv) measured at three locations indicated that the titanium bracket was uniformly sintered. Accordingly, titanium brackets thus fabricated exhibit a potential for clinical application. PMID:8876601

Deguchi, T; Ito, M; Obata, A; Koh, Y; Yamagishi, T; Oshida, Y

1996-07-01

33

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.

34

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

35

Exterior differentials in superspace and Poisson brackets  

NASA Astrophysics Data System (ADS)

It is shown that two definitions for an exterior differential in superspace, giving the same exterior calculus, yet lead to different results when applied to the Poisson bracket. A prescription for the transition with the help of these exterior differentials from the given Poisson bracket of definite Grassmann parity to another bracket is introduced. It is also indicated that the resulting bracket leads to generalization of the Schouten-Nijenhuis bracket for the cases of superspace and brackets of diverse Grassmann parities. It is shown that in the case of the Grassmann-odd exterior differential the resulting bracket is the bracket given on exterior forms. The above-mentioned transition with the use of the odd exterior differential applied to the linear even/odd Poisson brackets, that correspond to semi-simple Lie groups, results, respectively, in also linear odd/even brackets which are naturally connected with the Lie superalgebra. The latter contains the BRST and anti-BRST charges and can be used for calculation of the BRST operator cogomology.

Soroka, Dmitrij V.; Soroka, Vyacheslav A.

2003-03-01

36

Degenerate Odd Poisson Bracket on Grassmann Variables  

NASA Astrophysics Data System (ADS)

A linear degenerate odd Poisson bracket (antibracket) realized solely on Grassmann variables is presented. It is revealed that this bracket has at once three nilpotent $\\Delta$-like differential operators of the first, the second and the third orders with respect to the Grassmann derivatives. It is shown that these $\\Delta$-like operators together with the Grassmann-odd nilpotent Casimir function of this bracket form a finite-dimensional Lie superalgebra.

Soroka, V. A.

2000-05-01

37

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

38

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

39

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

40

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

PubMed Central

Objective To compare the influence of archwire material (NiTi, beta-Ti and stainless steel) and brackets design (self-ligating and conventional) on the frictional force resistance. Material and Methods Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M). The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement. Results Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials. Conclusion even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material. PMID:25025564

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

2014-01-01

41

The Effect of Different Soft Drinks on the Shear Bond Strength of Orthodontic Brackets  

PubMed Central

Objective: It is proved that acidic soft drinks that are commonly used, have an adverse effect on dental structures, and may deteriorate oral heath of our patients and orthodontic appliances. The aim of this study was to compare the effect of yoghurt drink with other soft drinks on the shear bond strength of orthodontic brackets. Materials and Methods: Seventy-five first premolar teeth extracted for orthodontic purposes were selected and standard twin metal brackets were bonded on the center of buccal surface with No-Mix composite. The teeth were thermocycled for 625 cycles and randomly divided into five groups of artificial saliva, carbonated yoghurt drink with lactic acid base, non-carbonated yoghurt drink with lactic acid base, 7 up with citric acid base and Pepsi with phosphoric acid base. In all groups, the teeth were immersed in liquid for five-minute sessions three times with equal intervening intervals for 3 months. SBS was measured by a universal testing machine with a speed of 0.5mm/min. Data was analyzed statistically by one-way ANOVA. Results: The results showed that mean values for the shear bond strength of carbonated yoghurt drinks, non-carbonated yoghurt drinks, 7up and Pepsi groups were 12.98(±2.95), 13.26(±4.00), 16.11(±4.89), 14.73(±5.10), respectively. There was no statistically significant difference among the groups (P-value= 0.238) Conclusion: Soft drinks used in this study did not decrease the bond strength of the brackets bonded with this specific type of composite. PMID:23066479

Omid Khoda, M.; Heravi, F.; Shafaee, H.; Mollahassani, H.

2012-01-01

42

Bracket study : textual, computational, and digital  

E-print Network

Bracket system is an important and characteristic component in the traditional Chinese architecture. Much has been studied about the system - its origin, historical evolution, structure, and composition - in the traditional ...

Wu, Qiong, 1972-

2003-01-01

43

Bihamiltonian cohomology of KdV brackets  

E-print Network

Using spectral sequences techniques we compute the bihamiltonian cohomology groups of the pencil of Poisson brackets of dispersionless KdV hierarchy. In particular this proves a conjecture of Liu and Zhang about the vanishing of such cohomology groups.

Guido Carlet; Hessel Posthuma; Sergey Shadrin

2014-06-21

44

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

Microsoft Academic Search

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

David Yarowsky; Grace Ngai

2001-01-01

45

The influence of bracket design on frictional losses in the bracket/arch wire system.  

PubMed

In arch guided tooth movement, the essential role played by bracket configuration with respect to sliding friction has been recognized by the manufacturers, a fact which has had an increasing impact on the design and marketing of new bracket models in recent years. The aim of the present in-vitro study was to investigate the influence of different bracket designs on sliding mechanics. Five differently shaped stainless steel brackets (Discovery: Dentaurum, Damon SL: A-Company, Synergy: Rocky Mountain Orthodontics, Viazis bracket and Omni Arch appliance: GAC) were compared in the 0.022"-slot system. The Orthodontic Measurement and Simulation System (OMSS) was used to quantify the difference between applied force (NiTi coil spring, 1.0 N) and orthodontically effective force and to determine leveling losses occurring during the sliding process in arch guided tooth movement. Simulated canine retraction was performed using continuous arch wires with the dimensions 0.019" x 0.025" (Standard Steel, Unitek) and 0.020" x 0.020" (Ideal Gold, GAC). Comparison of the brackets revealed friction-induced losses ranging from 20 to 70%, with clear-cut advantages resulting from the newly developed bracket types. However, an increased tendency towards leveling losses in terms of distal rotation (maximum 15 degrees) or buccal root torque (maximum 20 degrees) was recorded, especially with those brackets giving the arch wire increased mobility due to their shaping or lack of ligature wire. PMID:10546416

Schumacher, H A; Bourauel, C; Drescher, D

1999-01-01

46

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

PubMed Central

Background: The aim of the present study is to evaluate the effects of a fluoride-releasing composite resin bonding material on reducing enamel demineralization underneath and around orthodontic brackets and compare that with a conventional adhesive system. Materials and Methods: Buccal surfaces of 10 intact extracted premolar teeth were divided into two parts with nail varnish and stainless steel brackets were randomly bonded by two resin composite systems: (Transbond XT) and (Transbond XT plus Color Change) (3M, Unitek, Monrovia, CA, USA) on two sides of the teeth and then samples were placed in a demineralization solution. It is claimed that the second system has the ability of fluoride release. Elastic modulus and hardness of enamel were measured with nanoindentation test in 6 depths in 1-36 ?m from the enamel surface and in 7 regions: Control (intact enamel surface), underneath the brackets and also 50 and 100 ?m from the brackets edge. These nanomechanical features were evaluated in different regions and depths using analysis of variance and paired t-test (P < 0.05). Results: Considerable difference can be seen in different depths and regions in terms of hardness and elastic modulus. The region under the bracket with fluoridated adhesive shows similar results with intact enamel, whereas these parameters in fluoride less side show a significant reduction (P < 0.05). Conclusion: Results show that use of resin composite bonding system with the ability of fluoride release for bracket bonding, may reduce demineralization of enamel around brackets during orthodontic treatment. PMID:24688563

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

2014-01-01

47

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

48

Comparison of shear bond strength of brackets recycled using micro sandblasting and industrial methods.  

PubMed

Objective: To evaluate in vitro the shear bond strength of brackets recycled by sandblasting with aluminum oxide particles of different sizes or reconditioned industrially after successive rebonding. Materials and Methods: Eighty brackets were bonded and debonded sequentially three times. After the first debonding, brackets were divided into four groups: (group 1) sandblasting with aluminum oxide particles of 25 ?, (group 2) 50 ?, and (group 3) 110 ?, and (group 4) industrial recycling. Bond strength and adhesive material remaining on debonded bracket bases were evaluated for each successive debond. Results: No significant differences were detected between the four groups following the first recycle (P > .05). After the second recycle, bond strength was significantly greater for the industrially recycled group than the other groups (P < .016). When shear bond strength was compared within each recycling method, the bond strength of sandblasted brackets decreased with the increase of particle size and with each recycle; for the industrially recycled group, no significant differences were detected between the three sequences (P > .016). In the evaluation of bond material remnant, the industrially recycled group left significantly less bond material after successive recycling than the other groups did (P < .016). Within each recycling method, the adhesive remnant decreased significantly after successive debond (P < .016). Conclusions: Industrial recycling obtained better results than sandblasting after three successive debondings. The brackets' shear bond strength decreased as the size of the aluminum oxide particle used for sandblasting increased and as recycling was repeated. PMID:25230006

Montero, Manuela M Haro; Vicente, Ascensión; Alfonso-Hernández, Noelia; Jiménez-López, Manuel; Bravo-González, Luis-Alberto

2014-09-17

49

Frictional Resistance of Three Types of Ceramic Brackets  

PubMed Central

ABSTRACT Objectives To investigate the static frictional resistance at the bracket/archwire interface in two recently introduced bracket systems and compare them to conventional ceramic and conventional metal bracket systems. Three variables were considered including the bracket system, archwire type and archwire angulation. Material and Methods Four bracket systems were tested in vitro: Self ligating ceramic, ceramic with metal slot and module, conventional ceramic with module and conventional metal with module. A specially constructed jig and an Instron testing machine were used to measure the static frictional resistance for 0.014 inches round and 0.018 x 0.025 inches rectangular stainless steel wires at 0° and 7° angulations. Main outcome measures: static frictional force at the bracket/archwire interface; recorded and measured in units of force (Newtons). Results Self ligating ceramic and metal slot ceramic bracket systems generated significantly less static frictional resistance than conventional ceramic bracket systems with the wire at both angulations (P < 0.05). Changing the wire from 0.014 round to 0.018 x 0.025 rectangular wire significantly increased frictional forces for metal slot ceramic and conventional metal bracket systems (P < 0.01). Increasing wire angulation significantly increased frictional resistance at the bracket/archwire interface for all four types of bracket systems tested (P < 0.001). Conclusions Compared to conventional ceramic, self ligating ceramic and metal slot ceramic bracket systems should give improved clinical performance, matching that of conventional metal brackets. PMID:24478913

Williams, Claire L

2013-01-01

50

Ultrashort pulsed laser conditioning of human enamel: in vitro study of the influence of geometrical processing parameters on shear bond strength of orthodontic brackets.  

PubMed

The surfaces of 63 extracted premolar teeth were processed with intense ultrashort laser pulses (??=?795 nm; pulse duration, 120 fs; repetition rate, 1 kHz) to produce cross patterns with different pitches (s) in the micrometer range in order to evaluate the influence of such microstructures on the shear bond strengths of orthodontic brackets to enamel. The samples were classified in nine groups corresponding to the control group (raw samples) and eight different laser-processed groups (cross patterns with s increasing from 15 to 180 ?m). Brackets were luted with Transbond(TM) XT adhesive resin to all the samples; after 72 h, they all were submitted to strength test in a universal testing machine. Additionally, a third of the samples underwent morphological analysis of the debonded surface by means of scanning electron microscope microscopy and an analysis of the failure mode based on the adhesive remnant index. The results showed that enamel microstructuring with ultrashort laser pulses remarkably increase the bond strength of brackets. Dense cross patterns (s??90 ?m) give rise to smaller improvements of the bond strength. A strong correlation of this behavior with the predominant failure mode in both scenarios was found. So far, the best compromise between suitable adhesive efficiency, processing time minimization, and enamel surface preservation suggests the performance of cross patterns with pitches in the order of 90 ?m. PMID:24249356

Lorenzo, M C; Portillo, M; Moreno, P; Montero, J; García, A; Santos-Del Riego, S E; Albaladejo, A

2015-02-01

51

Interior view, detail to show typical bracket with gold leaf ...  

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

Interior view, detail to show typical bracket with gold leaf ornament, here the bracket is located the north of the speaker on the second floor - National Park Seminary, Ballroom, Linden Lane, Silver Spring, Montgomery County, MD

52

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

PubMed

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

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

2006-06-01

53

An Alternate Approach to the Lie Bracket on Hochschild Cohomology.  

E-print Network

We define Gerstenhaber's graded Lie bracket directly on complexes other than the bar complex, under some conditions. The Koszul complex of a Koszul algebra in particular satisfies our conditions. As examples we recover the Schouten-Nijenhuis bracket for a polynomial ring and the Gerstenhaber bracket for a group algebra of a cyclic group of prime order.

Cris Negron; Sarah Witherspoon

54

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

55

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

PubMed Central

Purpose: To evaluate the shear bond strength (SBS), adhesive remnant index (ARI), and microleakage of low-shrinking and conventional composites used as an orthodontic bracket bonding adhesive. Materials and Methods: A hundred twenty non-caries human premolars, extracted for orthodontic purposes, were used in this study. Sixty of them were separated into two groups. Brackets were bonded to the teeth in the test group with Silorane (3M-Espe) and control group with Transbond-XT (3M-Unitek). SBS values of these brackets were recorded in MPa using a universal testing machine. ARI scores were determined after the failure of brackets. The remaining 60 teeth were divided into two groups and microleakage was evaluated by the dye penetration method. Statistical analyses were performed by Wilcoxon, Pearson Chi-square, and Mann–Whitney U tests at P < 0.05 level. Results: The mean SBS for Transbond XT was significantly greater than low-shrinking composite (P < 0.001). Significant differences (?2 =29.60, P < 0.001) were present between the two groups for the ARI scores. Microleakage values were lower in low-shrinking composite than in the control group, and this difference was found to be statistically significant (P < 0.001). Conclusions: Although low-shrinking composite produced insufficient SBS and ARI scores, microleakage values were lower in low-shrinking composite than in the control group on the etched enamel surfaces, when used as a bracket bonding composite. PMID:24926207

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

2013-01-01

56

Pulpal Thermal Changes following Er-YAG Laser Debonding of Ceramic Brackets  

PubMed Central

Lasers are effective in debonding ceramic brackets. Unfortunately, while reducing the adhesive bond strength, lasers are also reported to increase pulpal temperature. The aim of this study was to evaluate the shear bond strengths and temperature increase levels after debonding ceramic brackets using an Er-YAG laser with or without water-cooling. Sixty polycrystalline upper premolar ceramic brackets were placed on the labial surface of sixty human premolar teeth which were randomly divided into three groups of twenty. A laser pulse at 5?W for 9 seconds was delivered to each bracket in both study groups either with water-cooling (water group) or without water-cooling (waterless group) using an Er-YAG laser. Debonding was performed 45 seconds after laser exposure and shear bond strengths were measured. Data comparison revealed a statistically significant difference between the groups. Mean temperature increases of 2.41°C and 4.59°C were recorded for the water and waterless laser groups, respectively. The shear bond strength value for the control group was 22.76?MPa and 10.46 and 6.36?MPa for the water and waterless laser groups, respectively. The application of Er-YAG laser with water-cooling was an efficient and safe method of debonding ceramic brackets. PMID:25197718

Oztoprak, Mehmet Oguz

2014-01-01

57

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

58

Effect of using self-etching primer for bonding orthodontic brackets.  

PubMed

Questions over the use of self-etching primers with composite resin adhesives in the bonding of orthodontic brackets remain unsolved. In addition, there are no previous reports on the efficacy of self-etching primers with resin-modified glass ionomer cements for bonding orthodontic brackets in orthodontic dentistry. The purpose of this study was to determine the shear bond strengths of orthodontic brackets bonded with one of four protocols: (1) a composite resin adhesive used with 40% phosphoric acid, (2) the same composite resin used with Megabond self-etching primer, (3) a resin-modified glass ionomer cement adhesive used with 10% polyacrylic acid enamel conditioner, and (4) the same resin-modified glass ionomer cement used with Megabond self-etching primer. The appearance of the tooth surfaces after acid etching or priming was observed with a field-emission scanning electron microscope (FE-SEM). When used with resin-modified glass ionomer cement, Megabond self-etching primer gave no significantly different shear bond strength compared with polyacrylic acid etching. But when used with composite resin adhesive, Megabond self-etching primer gave significantly lower shear bond strength than phosphoric acid etching. However, the shear bond strength of orthodontic brackets bonded with composite resin adhesive after Megabond priming was almost the same as that of brackets bonded with resin-modified glass ionomer cement after polyacrylic acid etching. FE-SEM observation revealed that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching. Megabond self-etching primer may be a candidate for bonding orthodontic brackets using the resin-modified glass ionomer cement for minimizing the amount of enamel loss. PMID:12518948

Yamada, Rieko; Hayakawa, Tohru; Kasai, Kazutaka

2002-12-01

59

Generalized nonholonomic mechanics, servomechanisms and related brackets  

Microsoft Academic Search

It is well known that nonholonomic systems obeying D’Alembert’s principle are described on the Hamiltonian side, after using the Legendre transformation, by the so-called almost-Poisson brackets. In this paper we define the Lagrangian and Hamiltonian sides of a class of generalized nonholonomic systems (GNHS), obeying a generalized version of D’Alembert’s principle, such as rubber wheels (like some simplified models of

H. Cendra; S. Grillo

2006-01-01

60

A Comparison of Gender and Socioeconomic Bracket in Fourth Grade Students when Measuring Volume  

NASA Astrophysics Data System (ADS)

The goal of this study was to assess students' abilities when measuring volume as well as providing a hands-on method for designing a water-filtration process. I studied the trends among gender, time, and ability to measure water in two different groups of fourth grade students. Fourth grade students from both higher income and lower income school districts visited a STEM (Science, Technology, Engineering, and Mathematics) Studio in order to participate in hands-on, problem-based learning. The students in this study attempted to solve the "Dirty Water Problem" by measuring 281ml of dirty water solution, and using household tools to filter and clean the dirty water. This study showed that 68% of students from a high-income socioeconomic bracket were able to measure a determined volume of water independently. Meanwhile, only 18% of students from a low-income socioeconomic bracket were able to complete the same task independently. In the low-income bracket, 78% of students required assistance measuring a volume of water, indicating that the majority of these students performed below grade level. Where time spent at the station was concerned, the difference between high-income and low-income socioeconomic brackets was insignificant. Key Words: STEM, measurement, volume, design, Dirty Water Problem, socioeconomic bracket.

Jennings, Kelly A.

61

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

62

Effect of time and pH on physical-chemical properties of orthodontic brackets and wires.  

PubMed

Abstract Objective: To test the hypothesis that treatment time, debris/biofilm, and oral pH have an influence on the physical-chemical properties of orthodontic brackets and arch wires. Materials and Methods: One hundred twenty metal brackets were evaluated. They were divided into four groups (n ?=? 30) according to treatment time: group C (control) and groups T12, T24, and T36 (brackets recovered after 12, 24, and 36 months of treatment, respectively). Rectangular stainless-steel arch wires that remained in the oral cavity for 12 to 24 months were also analyzed. Dimensional stability, surface morphology, composition of brackets, resistance to sliding of the bracket-wire set, surface roughness of wires, and oral pH were analyzed. One-way analysis of variance, followed by a Tukey multiple comparisons test, was used for statistical analysis (P < .05). Results: Carbon and oxygen were shown to be elements that increased expressively and in direct proportion to time, and there was a progressive increase in the coefficient of friction and roughness of wires as a function of time of clinical use after 36 months. Oral pH showed a significant difference between group T36 and its control (P ?=? .014). Conclusions: The hypothesis was partially accepted: treatment time and biofilm and debris accumulation in bracket slots were shown to have more influence on the degradation process and frictional force of these devices than did oral pH. PMID:25023707

Dos Santos, Aretha Aliny Ramos; Pithon, Matheus Melo; Carlo, Fabíola Galbiatti Carvalho; Carlo, Hugo Lemes; de Lima, Bruno Alessandro Silva Guedes; Dos Passos, Tibério Andrade; Lacerda-Santos, Rogério

2014-07-15

63

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

PubMed Central

Background: The aim of this study was to compare the effects of conventional acid etching and laser etching on the nano-mechanical properties of the dental enamel using nano-indentation test. Materials and Methods: In this experimental in vitro study, buccal surfaces of 10 premolars were divided into three regions. One of the regions was etched with 37% phosphoric acid and another etched with Er:YAG laser, the third region was not etched. The brackets were bonded to both of etched regions. After thermocycling for 500 cycles, the brackets were removed and the teeth were decoronated from the bracket bonding area. Seven nano-indentations were applied at 1-31 ?m depth from the enamel surface in each region. Mean values of the hardness and elastic modulus were analyzed with repeated measures analysis of variance and Tukey HSD tests, using the SPSS software (SPSS Inc., version16.0, Chicago, Il, USA). P < 0.05 was considered as significant. Results: The hardness up to 21 ?m in depth and elastic modulus up to 6 ?m in depth from the enamel surface for laser-etched enamel had significantly higher values than control enamel and the hardness up to 11 ?m in depth and elastic modulus up to 6 ?m in depth for acid-etched enamel had significantly lower values than the control enamel. Conclusion: The mechanical properties of the enamel were decreased after bracket bonding with conventional acid etching and increased after bonding with Er:YAG laser. PMID:24688560

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

2014-01-01

64

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

65

In Vitro Evaluation of Microleakage Around Orthodontic Brackets Using Laser Etching and Acid Etching Methods  

PubMed Central

Objective: path of microleakage between the enamel and adhesive potentially allows microbial ingress that may consequently cause enamel decalcification. The aim of this study was to compare microleakage of brackets bonded either by laser or acid etching techniques. Materials and Method: The specimens were 33 extracted premolars that were divided into three groups as the acid etching group (group 1), laser etching with Er:YAG at 100 mJ and 15 Hz for 15s (group 2), and laser etching with Er:YAG at 140 mJ and 15 Hz for 15s (group 3). After photo polymerization, the teeth were subjected to 500 thermal cycles. Then the specimens were sealed with nail varnish, stained with 2% methylen blue for 24hs, sectioned, and examined under a stereomicroscope. They were scored for marginal microleakage that occurred between the adhesive-enamel and bracket-adhesive interfaces from the occlusal and gingival margins. Data were analyzed with the Kruskal- Wallis test. Results: For the adhesive-enamel and bracket-adhesive surfaces, significant differences were not observed between the three groups. Conclusion: According to this study, the Er:YAG laser with 1.5 and 2.1 watt settings may be used as an adjunctive for preparing the surface for orthodontic bracket bonding.

Toodehzaeim, Mohammad Hossein; Yassaei, Sogra; Karandish, Maryam; Farzaneh, Sedigeh

2014-01-01

66

RSRM nozzle actuator bracket\\/lug fracture mechanics qualification test  

Microsoft Academic Search

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

Peggy Kelley

1993-01-01

67

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

68

The Poisson bracket on free null initial data for gravity.  

PubMed

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

Reisenberger, Michael P

2008-11-21

69

From Peierls brackets to a generalized Moyal bracket for type-I gauge theories  

E-print Network

In the space-of-histories approach to gauge fields and their quantization, the Maxwell, Yang--Mills and gravitational field are well known to share the property of being type-I theories, i.e. Lie brackets of the vector fields which leave the action functional invariant are linear combinations of such vector fields, with coefficients of linear combination given by structure constants. The corresponding gauge-field operator in the functional integral for the in-out amplitude is an invertible second-order differential operator. For such an operator, we consider advanced and retarded Green functions giving rise to a Peierls bracket among group-invariant functionals. Our Peierls bracket is a Poisson bracket on the space of all group-invariant functionals in two cases only: either the gauge-fixing is arbitrary but the gauge fields lie on the dynamical sub-space; or the gauge-fixing is a linear functional of gauge fields, which are generic points of the space of histories. In both cases, the resulting Peierls bracke...

Esposito, G; Esposito, Giampiero; Stornaiolo, Cosimo

2006-01-01

70

Orthodontic bracket designs and their impact on microbial profile and periodontal disease: A clinical trial  

PubMed Central

Aim: The aim of the present study was to compare the undisturbed plaque formation on teeth bonded with Preadjusted (Captain Ortho, Libral Traders, Mumbai, India) and Begg Brackets (Captain Ortho, Libral Traders, Mumbai, India) with nonbonded control sites via a de novo plaque growth over a period of 7 days. Materials and Methods: A clinical trial with the split-mouth design was set up enrolling 10 dental students. Within each subject sites with (Preadjusted) (P-site), Begg brackets (B-site) and control sites were followed. Plaque index and gingival index were recorded on days 3 and 7. Supra-gingival and sub-gingival plaque samples were taken from the brackets and the teeth on days 3 and 7, and were sent for aerobic and anaerobic culturing. The total number of bacterial colony forming units (CFU) was assessed for each sample using a colony counter. Tukeys and Dunnett test then statistically analyzed data. Results: The mean plaque index and gingival index increased on P-site and B-site on the third and 7th day. The shift from aerobic to anaerobic species was observed earlier in P-sites than in B-sites. The CFU were significantly higher for all sites on day 7 when compared with day 3. The aerobe/anaerobe CFU ratio was significantly lower in P-sites than in B-sites and then control showing an increase in the number of anaerobic species on the 3rd and 7th day (P < 0.05). Based on observed means, the mean difference was significant (P < 0.05). Conclusion: The present data suggest that Preadjusted brackets accumulated more plaque than Begg brackets. Bracket design can have a significant impact on bacterial load and on periodontal parameters. PMID:25426456

Moolya, Nikesh N; Shetty, Arvind; Gupta, Neha; Gupta, Anvesha; Jalan, Vivek; Sharma, Rashmi

2014-01-01

71

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

72

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

73

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

74

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

75

21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 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...

2014-04-01

76

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

77

Probability Bracket Notation and Probability Modeling  

E-print Network

Inspired by the Dirac notation, a new set of symbols, the Probability Bracket Notation (PBN) is proposed for probability modeling. By applying PBN to discrete and continuous random variables, we show that PBN could play a similar role in probability spaces as the Dirac notation in Hilbert vector spaces. The time evolution of homogeneous Markov chains with discrete-time and continuous-time are discussed in PBN. Our system state p-kets are identified with the probability vectors, while our system state p-bra can be identified with the Doi state function or the Peliti standard bra. We also suggest that, by transforming from the Schrodinger picture to the Heisenberg picture, the time-dependence of a system p-ket of a homogeneous MC can be shifted to the observable as a stochastic process.

Xing M. Wang

2009-09-07

78

Microhardness of enamel adjacent to orthodontic brackets after CO2 laser irradiation and fluoride application.  

PubMed

This study evaluated the effectiveness of carbon dioxide (CO2) laser combined or not with fluoride application on the surface microhardness of enamel adjacent to orthodontic brackets. Fifteen human molars were selected from which 30 enamel fragments measuring 4 mm2 were obtained. The fragments were embedded in PCV tubes with acrylic resin and prepared using water abrasive paper, felt disks and alumina. Orthodontic brackets cut in half were bonded to enamel and 3 microhardness readings were performed on the adjacent surface, as follows: initial, after cariogenic challenge and final. The specimens were divided into the following 3 groups (n=10): Group C: control, Group L: irradiated with CO2 laser, and Group FL: topical fluoride application and CO2 laser irradiation. After initial reading, the specimens were placed in a demineralizing solution for 32 h and the second reading was to verify if demineralization was uniform in all groups. After the treatments, the specimens were submitted to DES-RE cycling for 8 days followed by final surface microhardness reading. The data were analyzed statistically using ANOVA and Duncan test (?=0.05). At the final measurement Group FL obtained higher microhardness value than Groups C and L (p<0.05). Groups L and FL were statistically superior to Group C (p<0.05). Irradiation with CO2 laser around orthodontic brackets combined or not with topical fluoride application was effective to increase the surface microhardness of enamel. PMID:24474294

Stangler, Leonardo Pucci; Romano, Fábio Lourenço; Shirozaki, Mariana Umekita; Galo, Rodrigo; Afonso, Alessandra Marques Correa; Borsatto, Maria Cristina; Matsumoto, Mírian Aiko Nakane

2013-01-01

79

Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.  

PubMed

Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets. PMID:25027301

Krishnan, Manu; Tiwari, Brijesh; Seema, Saraswathy; Kalra, Namitha; Biswas, Papiya; Rajeswari, Kotikalapudi; Suresh, Madireddy Buchi; Johnson, Roy; Gokhale, Nitin M; Iyer, Satish R; Londhe, Sanjay; Arora, Vimal; Tripathi, Rajendra P

2014-11-01

80

In vitro evaluation of corrosion and cytotoxicity of orthodontic brackets.  

PubMed

The corrosion resistance of AISI 304 stainless steel (AISI 304 SS) and manganese stainless steel (low-nickel SS) brackets in artificial saliva was investigated. The cytotoxic effects of their corrosion products on L929 cell culture were compared by two assays, crystal violet, to evaluate cell viability, and MTT (3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide), for cell metabolism and proliferation. The atomic absorption spectroscopic analysis of the corrosion products demonstrated that nickel and manganese ion concentrations were higher for the AISI 304 SS-bracket immersion solution as compared with the low-nickel SS brackets. Scanning electron microscopy and energy-dispersive spectroscopy demonstrated less corrosion resistance for the AISI 304 SS brackets. Although none of the bracket extracts altered L929 cell viability or morphology, the AISI 304 SS-bracket extracts decreased cellular metabolism slightly. The results indicated that the low-nickel SS presents better in vitro biocompatibility than AISI 304 SS brackets. Abbreviations used: AISI, American Iron and Steel Institute; EDS, energy-dispersive spectroscopy; OD, optical density; ISO, International Organization for Standardization; MTT, (3-{4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NiSO(4), nickel sulfate; SEM, standard error of the mean; WHO, World Health Organization; and TNF, tumor necrosis factor. PMID:17452565

Costa, M T; Lenza, M A; Gosch, C S; Costa, I; Ribeiro-Dias, F

2007-05-01

81

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

82

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

83

Cortical Surface-Based Analysis I. Segmentation and Surface Reconstruction  

E-print Network

cortex, which makes up the largest part of the human brain, has the topology of a 2-D sheet and a highly use of cortical surface-based analysis and visualization meth- ods in functional brain imaging. 1999 have been rou- tinely applied. Nevertheless, most approaches to analyz- ing and displaying human brain

Sereno, Martin

84

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

PubMed Central

Objective The purpose of this study was to evaluate the effects of three different surface conditioning methods on the shear bond strength (SBS) of metal brackets bonded directly to gold alloy with chemically cured resin. Methods Two hundred ten type III gold alloy specimens were randomly divided into six groups according to the combination of three different surface conditioning methods (aluminum oxide sandblasting only, application of a metal primer after aluminum oxide sandblasting, silica coating and silanation) and thermocycling (with thermocycling, without thermocycling). After performing surface conditioning of specimens in accordance with each experimental condition, metal brackets were bonded to all specimens using a chemically cured resin. The SBS was measured at the moment of bracket debonding, and the resin remnants on the specimen surface were evaluated using the adhesive remnant index. Results Application of metal primer after aluminum oxide sandblasting yielded a higher bond strength than that with aluminum oxide sandblasting alone (p < 0.001), and silica coating and silanation yielded a higher bond strength than that with metal primer after aluminum oxide sandblasting (p < 0.001). There was no significant change in SBS after thermocycling in all groups. Conclusions With silica coating and silanation, clinically satisfactory bond strength can be attained when metal brackets are directly bonded to gold alloys using a chemically cured resin. PMID:24892023

Ryu, Min-Ju; Lim, Sung-Hoon

2014-01-01

85

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

86

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

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

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

87

Analysis of Bracket Assembly for Portable Leak Detector Station  

SciTech Connect

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

ZIADA, H.H.

1999-08-19

88

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

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

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

89

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

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

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

90

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

91

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.

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

2014-01-01

92

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

PubMed Central

Objective To test the null hypothesis that no difference exists between the effects of at-home bleaching and in-office bleaching on shear bond strength (SBS) with bracket bonding at 4 different time intervals after dental bleaching. Methods Ninety extracted human premolars were randomly divided into 9 groups (n = 10) according to the bleaching methods used (at-home bleaching and in-office bleaching) and the storage time in artificial saliva (30 min, 1 day, 2 weeks, and 3 weeks before bonding). The control group was stored in artificial saliva for 7 days. Brackets were bonded with the Transbond XT adhesive system, and SBS testing was performed. The adhesive remnant index (ARI) was used to assess the amount of resin remaining on the enamel surfaces after debonding. The SBS data were analyzed by analysis of variance (ANOVA) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. Significance for all statistical tests was predetermined to be p < 0.05. Results The SBS of the unbleached group was significantly higher (p < 0.05) than that of the bleached groups (except for the group bonded 30 min after at-home bleaching). Conclusions The null hypothesis was not totally rejected. All bleaching groups tested had decreased SBS of the brackets to the enamel, except for the group bonded 30 min after at-home bleaching. The SBS returned to values close to those of the unbleached enamel within 3 weeks following bleaching. PMID:24228239

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

2013-01-01

93

Probability Bracket Notation: Probability Space, Conditional Expectation and Introductory Martingales  

E-print Network

In this paper, we continue to explore the consistence and usability of Probability Bracket Notation (PBN) proposed in our previous articles. After a brief review of PBN with dimensional analysis, we investigate probability spaces in terms of PBN by introducing probability spaces associated with random variables (R.V) or associated with stochastic processes (S.P). Next, we express several important properties of conditional expectation (CE) and some their proofs in PBN. Then, we introduce martingales based on sequence of R.V or based on filtration in PBN. In the process, we see PBN can be used to investigate some probability problems, which otherwise might need explicit usage of Measure theory. Whenever applicable, we use dimensional analysis to validate our formulas and use graphs for visualization of concepts in PBN. We hope this study shows that PBN, stimulated by and adapted from Dirac notation in Quantum Mechanics (QM), may have the potential to be a useful tool in probability modeling, at least for those who are already familiar with Dirac notation in QM.

Xing M. Wang

2009-10-15

94

Fuzzy vector median-based surface smoothing.  

PubMed

This paper proposes a novel approach for smoothing surfaces represented by triangular meshes. The proposed method is a two-step procedure: surface normal smoothing through fuzzy vector median (FVM) filtering followed by integration of surface normals for vertex position update based on the least square error (LSE) criteria. Median and Order Statistic-based filters are extensively used in signal processing, especially image processing, due to their ability to reject outliers and preserve features such as edges and monotonic regions. More recently, fuzzy ordering theory has been introduced to allow averaging among similarly valued samples. Fuzzy ordering theory leads naturally to the fuzzy median, which yields improved noise smoothing over traditional crisp median filters. This paper extends the fuzzy ordering concept to vector-based data and introduces the fuzzy vector median filter. The application of FVM filters to surface normal smoothing yields improved results over previously introduced normal smoothing algorithms. The improved filtering results, coupled with LSE vertex position update, produces surface smoothing that minimizes the effects of noise while simultaneously preserving detail features. The proposed method is simple to implement and relatively fast. Simulation results are presented showing the performance of the proposed method and its advantages over commonly used surface smoothing algorithms. Additionally, optimization procedures for FVM filters are derived and evaluated. PMID:18579957

Shen, Yuzhong; Barner, Kenneth E

2004-01-01

95

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

96

Surface modification of polypropylene based particle foams  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

97

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

98

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

99

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

PubMed

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

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

2006-07-01

100

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 {({A},{\\cdot_?\\cdot})} of a differential algebra {{A}} and a bilinear operation called the {?} -bracket. We extend the definition to the class of algebras {{A}} endowed with {d ? 1} 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

2014-11-01

101

Poisson-Lie Odd Bracket on Grassmann Algebra  

NASA Astrophysics Data System (ADS)

A Poisson-Lie odd bracket realized solely in terms of Grassmann variables is suggested. It was found that with the bracket, corresponding to a semi-simple Lie algebra, both a Grassmann-odd Casimir function and invariant (with respect to this group) nilpotent differential operators of the first, second and third orders are naturally related and enter into a finite-dimensional Lie superalgebra. A relation of the quantities, forming this Lie superalgebra, with the BRST charge and operator for the ghost number is indicated.

Soroka, Dmitrij V.; Soroka, Vyacheslav A.

2006-03-01

102

Generating Surface Textures based on Cellular Networks  

Microsoft Academic Search

This paper describes a method allowing the automatic multi-tex- turing and simulation of surface imperfections based on a cellu- lar network. In this representation, networks of connected cells are constructed in a natural and dynamic way allowing simulta- neously real-time and multi-behavior simulation. We also intro- duce an original technique to store cells in space in a fast and boundless

Stéphane Gobron; Denis Finck

2006-01-01

103

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

104

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

PubMed Central

Background Self-adhesive resin cements do not require the surface treatment of teeth and are said to release fluoride, which makes them suitable candidates for bonding of orthodontic brackets. The objectives of this study was to investigate the shear bond strength (SBS) of self-adhesive resin cements on etched on non-etched surfaces in vitro and to assess their fluoride release features. Materials and Methods Four fluoride-releasing dual-cure self-adhesive resin cements were investigated. For SBS experiment, 135 freshly extracted human maxillary premolars were used and divided into nine groups of 15 teeth. In the control group, brackets were cemented by Transbond XT (3M Unitek, USA), in four groups self-adhesive resin cements were used without acid-etching and in four groups self-adhesive cements were applied on acid-etched surfaces and the brackets were then deboned in shear with a testing machine. Adhesive remnant index (ARI) scores were also calculated. For fluoride release investigation, 6 discs were prepared for each self-adhesive cement. Transbond XT and Fuji Ortho LC (GC, Japan) served as negative and positive control groups, respectively. The fluoride release of each disc into 5 ml of deionized water was measured at days 1, 2, 3, 7, 14, 28, and 56 using a fluoride ion-selective electrode connected to an ion analyzer. To prevent cumulative measurements, the storage solutions were changed daily. Results The SBS of brackets cemented with Transbond XT were significantly higher compared to self-adhesives applied on non-etched surfaces (P<0.001). However, when the self-adhesive resin cements were used with enamel etching, no significant differences was found in the SBS compared to Transbond XT, except for Breeze. The comparisons of the ARI scores indicated that bracket failure modes were significantly different between the etched and non-etched groups. All self-adhesive cements released clinically sufficient amounts of fluoride for an extended period of time. Conclusion For the tested cements, the strongest bonds were obtained by enamel acid-etching prior to bracket bonding. All the self-adhesive resin cements had significant long-term fluoride release and could be recommended as suitable fluoride-releasing orthodontic bonding materials. PMID:24163808

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

2013-01-01

105

Analysis of Bracket Assembly for Diversion Box Leak Detector  

SciTech Connect

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

ZIADA, H.H.

1999-08-19

106

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

107

hal00009145, RANKIN-COHEN BRACKETS ON QUASIMODULAR  

E-print Network

AND EMMANUEL ROYER Abstract. We give the algebra of quasimodular forms a collection of Rankin-Cohen operatorshal­00009145, version 2 ­ 12 Apr 2008 RANKIN-COHEN BRACKETS ON QUASIMODULAR FORMS FRAN�OIS MARTIN derivation. Rankin-Cohen operators are useful for proving arithmetical identities. In particular, we explain

Paris-Sud XI, Université de

108

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

109

RANKIN-COHEN BRACKETS AND ASSOCIATIVITY MICHAEL PEVZNER  

E-print Network

RANKIN-COHEN BRACKETS AND ASSOCIATIVITY MICHAEL PEVZNER Abstract. Don Zagier introduced in 1956 by R.A. Rankin [13]. Nineteen years later H. Cohen [5] investigated this problem in the framework as in the representation theory of the Lie group SL(2, R). Notice that their generalizations for different series of simple

Boyer, Edmond

110

Principal Component Based Diffeomorphic Surface Mapping  

PubMed Central

We present a new diffeomorphic surface mapping algorithm under the framework of large deformation diffeomorphic metric mapping (LDDMM). Unlike existing LDDMM approaches, this new algorithm reduces the complexity of the estimation of diffeomorphic transformations by incorporating a shape prior in which a nonlinear diffeomorphic shape space is represented by a linear space of initial momenta of diffeomorphic geodesic flows from a fixed template. In addition, for the first time, the diffeomorphic mapping is formulated within a decision-theoretic scheme based on Bayesian modeling in which an empirical shape prior is characterized by a low dimensional Gaussian distribution on initial momentum. This is achieved using principal component analysis (PCA) to construct the eigenspace of the initial momentum. A likelihood function is formulated as the conditional probability of observing surfaces given any particular value of the initial momentum, which is modeled as a random field of vector-valued measures characterizing the geometry of surfaces. We define the diffeomorphic mapping as a problem that maximizes a posterior distribution of the initial momentum given observable surfaces over the eigenspace of the initial momentum. We demonstrate the stability of the initial momentum eigenspace when altering training samples using a bootstrapping method. We then validate the mapping accuracy and show robustness to outliers whose shape variation is not incorporated into the shape prior. PMID:21937344

Younes, Laurent; Miller, Michael I.

2013-01-01

111

An Investigation about the Influence of Bleaching on Shear Bond Strength of Orthodontic Brackets and on Enamel Colour  

PubMed Central

The aim of the study was to investigate the effect of bleaching on the colouration of tooth enamel and shear bond strength of orthodontic ceramic brackets based upon current whitening practice. The bleaching and bonding techniques were performed on extracted bovine teeth for the investigation of their colorimetric spectrum and the adhesive bond strength on surface enamel. One group was designated as the control group with no pre-treatment. Another group was treated with a 45% hydrogen peroxide solution prior to bonding. The difference in colour was expressed as the Euclidian distance ?E. The resulting shear bond strength was analyzed and evaluated by scores of Adhesion Remnant Index. Statistical analysis was performed using the Kruskall-Wallis and post-hoc test. The colorimetric analysis revealed statistically significant differences between original and bleached as well as bleached and debonded teeth setting off a blue colour shift. Furthermore, statistically there was no significant difference noted in bonding strength between non-treated surfaces and those treated with peroxide. It can be concluded that peroxide pre-treatment does result in colour differences of teeth. Bonding and debonding procedures seem to have no statistically significant influence on the enamel colour using current materials. PMID:22536518

Immerz, Isabell; Proff, Peter; Roemer, Piero; Reicheneder, Claudia; Faltermeier, Andreas

2012-01-01

112

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

113

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

114

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

PubMed Central

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

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

2013-01-01

115

Surface Functionalization of Graphene-based Materials  

NASA Astrophysics Data System (ADS)

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

Mathkar, Akshay

116

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

117

A study of frictional forces between orthodontic brackets and archwires.  

PubMed

The differences in magnitude of static and kinetic frictional forces generated by 0.022 x 0.030-inch stainless steel (Dentaurum) and polycrystalline ceramic (Transcend) brackets in combination with archwires of different sizes (0.018 inch and 0.019 x 0.025 inch) and materials (stainless steel, nickel-titanium, and beta-titanium) at a constant ligature force were investigated. A friction-testing assembly using the Instron machine was used. In all cases, the static frictional force was greater than the kinetic frictional force. There were no significant differences in the frictional forces generated by stainless steel and polycrystalline ceramic brackets. Beta-titanium archwires produced greater frictional forces than the other two materials. Increasing the archwire diameter increased the frictional force. PMID:7857894

Downing, A; McCabe, J; Gordon, P

1994-11-01

118

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

119

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

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

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

120

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

121

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

122

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

123

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

124

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

125

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

PubMed Central

Background: Based on contradictory findings concerning the use of lasers for enamel etching, the purpose of this study was to investigate the shear bond strength of teeth prepared for bonding with Er-YAG laser etching and compare them with phosphoric acid etching. Materials and Methods: In this in vitro study forty – eight premolars, extracted for orthodontic purposes were randomly divided in to three groups. Thirty-two teeth were exposed to laser energy for 25 s: 16 teeth at 100 mj setting and 16 teeth at 150 mj setting. Sixteen teeth were etched with 37% phosphoric acid. The shear bond strength of bonded brackets with the Transbond XT adhesive system was measured with the Zwick testing machine. Descriptive statistics, Kolmogorov–Smirnov test, of homogeneity of variances, one- way analysis of variances and Tukey's test and Kruskal Wallis were used to analyze the data. Results: The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa). Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P < 0.001). Conclusions: laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive – enamel interface and is not safe for enamel during debonding. PMID:23087733

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

2012-01-01

126

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

127

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

128

Compatibility, Multi-brackets and Integrability of Systems of PDEs  

Microsoft Academic Search

We establish an efficient compatibility criterion for a system of generalized complete intersection type in terms of certain\\u000a multi-brackets of differential operators. These multi-brackets generalize the higher Jacobi-Mayer brackets, important in the\\u000a study of evolutionary equations and the integrability problem. We also calculate Spencer ?-cohomology of generalized complete intersections and evaluate the formal functional dimension of the solutions space. The

Boris Kruglikov; Valentin Lychagin

2010-01-01

129

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

PubMed Central

AIM: The aim of this study was to compare frictional resistance which was produced between conventional brackets (0.022 slot Otho-Organiser) and self ligating brackets (active Forestadent and passive Damon III) by using various arch wire combinations (0.016 Niti, 0.018 Niti, 0.017 x 0.025 SS and 0.019 x 0.025 SS). Methods: An experimental model which consisted of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces which were produced by SLBs (self ligating brackets) and CELs (conventional elastomeric ligatures) with use of 0.016 nickel titanium, 0.018 nickel titanium, 0.017 X 0.025”stainless steel and 0.019 X 0.025”stainless steel wires. Statistical analysis: One way ANOVA test was used to study the effect of the bracket type, wire alloy and section on frictional resistance test . Results: Conventional brackets produced highest levels of friction for all bracket/archwire combinations. Both Damon III and Forestadent brackets were found to produce significantly lower levels of friction when they were compared with elastomerically tied conventional brackets. Conclusion: SLBs are valid alternatives for low friction during sliding mechanics. PMID:24995241

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

2014-01-01

130

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

131

Surface modified amorphous ribbon based magnetoimpedance biosensor.  

PubMed

Magnetoimpedance (MI) changes due to surface modification of the sensitive element caused by human urine, were studied with the aim of creating a robust biosensor working on a principle of electrochemical magnetoimpedance spectroscopy. A biosensor prototype with an as-quenched amorphous ribbon sensitive element was designed and calibrated for a frequency range of 0.5-10 MHz at a current intensity of 60 mA. Measurements as a function of the exposure time were made both in a regime where chemical surface modification and MI measurements were separated as well as in a regime where they were done simultaneously. The MI variation was explained by the change of the surface magnetic anisotropy. It was shown that the magnetoimpedance effect can be successfully employed as a new option to probe the electric features of the Fe(5)Co(70)Si(15)B(10) amorphous ribbon magnetic electrode surface modified by human urine. PMID:16914305

Kurlyandskaya, Galina V; Fal Miyar, Vanessa

2007-04-15

132

[An in-vitro study of the bonding and fracture pattern of light-hardening, fluoride-releasing bonding materials in metal brackets].  

PubMed

Three hundred bovine incisors, which were divided into 6 groups of 50 teeth each, were used in this study. Two types of metal brackets, 1 with a conventional foil mesh base and the other with a photo-etched Micro-Loc base, were adhered to the teeth with 3 different bonding agents, namely, Sequence, a fluoride-releasing, light-activated composite, Photac-Fil, a light-hardened glass ionomer cement, and, in the control group, Concise, a 2-component composite which hardens chemically. A universal testing machine was employed to test tensile bonding strength and the site of failure was visually determined and analyzed. The study showed that Sequence can be considered as a qualitatively equal alternative to Concise. Both composites demonstrate equal tensile bonding strength. The use of Photac-Fil, the light-hardened glass ionomer bonding agent, cannot be recommended. It possesses significantly less tensile bonding strength than the other 2 bonding agents. Sequence and Concise, which showed better results with the brackets with conventional foil mesh base than with the brackets with photo-etched Micro-Loc base, had no significant differences in their failure sites. The interface of the composite with the bracket was the main failure site. Both composites demonstrated a significantly reduced rate of failure at the interface of the composite with the enamel, when they were used with the brackets with the Micro-Loc base. This differed from the failure site of Photac-Fil, when the photo-etched base was used. With Photac-Fil the main site of failure came at the interface of the enamel with this glass ionomer cement.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7851826

Eberhard, H; Hirschfelder, U; Nkenke, E; Boulouchou, O; Martus, P

1994-12-01

133

Surface albedo based on geostationary satellite observations  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

134

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...

135

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.

136

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

137

Surface plasmon modes revealed by fast electron based spectroscopies  

E-print Network

Surface plasmon modes revealed by fast electron based spectroscopies Arthur Losquin Laboratoire de, fast electron based spectroscopies, EELS and CL studies of SP modes - Experimental details - Electron Energy Loss Spectroscopy (EELS) and Cathodoluminescence (CL): nanometric optical spectroscopies

138

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

139

Ricci Flow-based Spherical Parameterization and Surface Registration.  

PubMed

This paper presents an improved Euclidean Ricci flow method for spherical parameterization. We subsequently invent a scale space processing built upon Ricci energy to extract robust surface features for accurate surface registration. Since our method is based on the proposed Euclidean Ricci flow, it inherits the properties of Ricci flow such as conformality, robustness and intrinsicalness, facilitating efficient and effective surface mapping. Compared with other surface registration methods using curvature or sulci pattern, our method demonstrates a significant improvement for surface registration. In addition, Ricci energy can capture local differences for surface analysis as shown in the experiments and applications. PMID:24019739

Chen, X; He, H; Zou, G; Zhang, X; Gu, X; Hua, J

2013-09-01

140

Ricci Flow-based Spherical Parameterization and Surface Registration  

PubMed Central

This paper presents an improved Euclidean Ricci flow method for spherical parameterization. We subsequently invent a scale space processing built upon Ricci energy to extract robust surface features for accurate surface registration. Since our method is based on the proposed Euclidean Ricci flow, it inherits the properties of Ricci flow such as conformality, robustness and intrinsicalness, facilitating efficient and effective surface mapping. Compared with other surface registration methods using curvature or sulci pattern, our method demonstrates a significant improvement for surface registration. In addition, Ricci energy can capture local differences for surface analysis as shown in the experiments and applications. PMID:24019739

Chen, X.; He, H.; Zou, G.; Zhang, X.; Gu, X.; Hua, J.

2013-01-01

141

Study of the composition, structure, and optical properties of a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket films erbium doped from the Er(pd){sub 3} complex compound  

SciTech Connect

Rutherford backscattering, IR spectroscopy, ellipsometry, and atomic-force microscopy are used to perform an integrated study of the composition, structure and optical properties of a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket amorphous films. The technique employed to obtain the a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket amorphous films includes the high-frequency decomposition of a mixture of gases, (SiH{sub 4}){sub a} + (CH{sub 4}){sub b}, and the simultaneous thermal evaporation of a complex compound, Er(pd){sub 3}. It is demonstrated that raising the amount of CH{sub 4} in the gas mixture results in an increase in the carbon content of the films under study and an increase in the optical gap E{sub g}{sup opt} from 1.75 to 2.2 eV. Changes in the composition of a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket amorphous films, accompanied, in turn, by changes in the optical constants, are observed in the IR spectra. The ellipsometric spectra obtained are analyzed in terms of multiple-parameter models. The conclusion is made on the basis of this analysis that the experimental and calculated spectra coincide well when variation in the composition of the amorphous films with that of the gas mixture is taken into account. The existence of a thin (6-8 nm) silicon-oxide layer on the surface of the films under study and the validity of using the double-layer model in ellipsometric calculations is confirmed by the results of structural analyses by atomic-force microscopy.

Kudoyarova, V. Kh., E-mail: kudoyarova@mail.ioffe.ru; Tolmachev, V. A.; Gushchina, E. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2013-03-15

142

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

143

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

144

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

145

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

146

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

147

MOVING FRAMES, GEOMETRIC POISSON BRACKETS AND THE KDV-SCHWARZIAN EVOLUTION OF PURE SPINORS  

E-print Network

MOVING FRAMES, GEOMETRIC POISSON BRACKETS AND THE KDV-SCHWARZIAN EVOLUTION OF PURE SPINORS GLORIA brackets. The resulting restriction is given by a decoupled system of KdV Poisson structures. We define system of KdV equations on the invariants of projective type, when restricted to a certain level set. We

148

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

149

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

150

Evaluation of Self-Etching Adhesive and Er:YAG Laser Conditioning on the Shear Bond Strength of Orthodontic Brackets  

PubMed Central

The purpose of this study was to evaluate the shear bond strength, the adhesive remnant index scores, and etch surface of teeth prepared for orthodontic bracket bonding with self-etching primer and Er:YAG laser conditioning. One hundred and twenty bovine incisors were randomly divided into four groups. In Group I (Control), the teeth were conditioned with 35% phosphoric acid for 15 seconds. In Group II the teeth were conditioned with Transbond Plus SEP (5?sec); III and IV were irradiated with the Er:YAG 150?mJ (11.0?J/cm2), 150?mJ (19.1?J/cm2), respectively, at 7–12?Hz with water spray. After surface preparation, upper central incisor stainless steel brackets were bonded with Transbond Plus Color Change Adhesive. The teeth were stored in water at 37°C for 24 hours and shear bond strengths were measured, and adhesive remnant index (ARI) was determined. The conditioned surface was observed under a scanning electron microscope. One-way ANOVA and chi-square test were used. Group I showed the significantly highest values of bond strength with a mean value of 8.2 megapascals (MPa). The lesser amount of adhesive remnant was found in Group III. The results of this study suggest that Er:YAG laser irradiation could not be an option for enamel conditioning. PMID:24228014

Contreras-Bulnes, Rosalía; Scougall-Vilchis, Rogelio J.; Rodríguez-Vilchis, Laura E.; Centeno-Pedraza, Claudia; Olea-Mejía, Oscar F.; Alcántara-Galena, María del Carmen Z.

2013-01-01

151

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

152

Patterned superhydrophobic surface based on Pd-based metallic glass  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

153

Surface wave Cherenkov maser based on a periodic lattice  

NASA Astrophysics Data System (ADS)

The excitation of a surface wave cavity based on a two-dimensional periodic structure by an energy source, such as relativistic electrons, results in stimulated, single frequency coherent emission. A high-Q cavity has been achieved via a resonant coupling between surface waves and volume waves. The concept of a Cherenkov maser based on the surface wave cavity is discussed and results of numerical studies presented. Links between the model described and the concept of a surface plasmon amplifier, which has been recently introduced are described.

Konoplev, I. V.; Fisher, L.; Cross, A. W.; Phelps, A. D. R.; Ronald, K.; Robertson, C. W.

2010-06-01

154

Plasma based Ar+ beam assisted poly(dimethylsiloxane) surface modification  

NASA Astrophysics Data System (ADS)

Plasma based Ar+ beam performed in RF (13.56 MHz) low-pressure (200 mTorr) glow discharge (at 100 W, 1200 W and 2500 W) with a serial capacitance was employed for surface modification of poly(dimethylsiloxane) (PDMS) aimed at improvement of its interactions with living cells. The presence of a serial capacitance ensures arise of an ion-flow inside the plasma volume directed toward the treated sample and the vary of the discharge power ensures varied density of the ion-flow. XPS analysis was performed to study the changes in the surface chemical composition of the modified samples and the corresponding changes in the surface energy were monitored by contact angle measurements. We found that plasma based Ar+ beam transforms the initially hydrophobic PDMS surface into a hydrophilic one mainly due to a raising of the polar component of the surface tension, this effect being most probably due to an enrichment of the modified surface layer with permanent dipoles of a [SiOx]-based network and elimination of the original methyl groups. The initial adhesion of human fibroblast cells was studied on the described above plasma based Ar+ beam modified and acrylic acid (AA) grafted or not fibronectin (FN) pre-coated or bare surfaces. The cell response seems to be related with the peculiar structure and wettability of the modified PDMS surface layer after plasma based Ar+ beam treatment followed or not by AA grafting.

Vladkova, T. G.; Keranov, I. L.; Dineff, P. D.; Youroukov, S. Y.; Avramova, I. A.; Krasteva, N.; Altankov, G. P.

2005-07-01

155

Hall position encoder-based touch surface  

Microsoft Academic Search

We can note that in these days touch screen technology began to flourish and it is more widely used both in hardware and in different applications. A touch screen based interface is beginning to be a basic requirement in almost every mobile appliance, and at the same time demand to equip other products with this technology is on the rise.

Norbert Hoz; Jozsef Veres; Gyorgy Cserey

2011-01-01

156

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...

157

Femtosecond laser surface texturing of a nickel-based superalloy  

Microsoft Academic Search

Femtosecond laser (180fs, 775nm, 1kHz) surface modification of the nickel-based superalloy C263 is investigated. The laser beam was scanned onto areas on the substrate with macroscopic dimensions using different fluences (F=0.28–30J\\/cm2), speeds (?=1–10mm\\/s) and number of overscans (5–90). The evolution of surface morphology, roughness, ablation depth and volume ablation rate with laser micromachining parameters were determined. The surface morphology is

N. G. Semaltianos; W. Perrie; M. Sharp; G. Dearden; K. G. Watkins

2008-01-01

158

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

159

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

160

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

161

Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched  

PubMed Central

Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG) laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under ×10 magnification and adhesive remnant index (ARI) score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa) was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa) (P = 0.41). There was no significant difference in the ARI scores between two groups (P = 0.08). However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching. PMID:25097641

Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh

2014-01-01

162

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.

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

2015-01-01

163

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

164

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

165

Rough surface scattering based on facet model  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

166

Surface bond strength in nickel based alloys.  

PubMed

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

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

2013-12-01

167

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

PubMed

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

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

2014-05-01

168

Surface versus Edge-Based Determinants of Visual Recognition.  

ERIC Educational Resources Information Center

The latency at which objects could be identified by 126 subjects was compared through line drawings (edge-based) or color photography (surface depiction). The line drawing was identified about as quickly as the photograph; primal access to a mental representation of an object can be modeled from an edge-based description. (SLD)

Biederman, Irving; Ju, Ginny

1988-01-01

169

(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

170

Algebraic construction of a Nambu bracket for the two-dimensional vorticity equation  

PubMed Central

So far fluid mechanical Nambu brackets have mainly been given on an intuitive basis. Alternatively an algorithmic construction of such a bracket for the two-dimensional vorticity equation is presented here. Starting from the Lie–Poisson form and its algebraic properties it is shown how the Nambu representation can be explicitly constructed as the continuum limit from the structure preserving Zeitlin discretization. PMID:21980219

Sommer, M.; Brazda, K.; Hantel, M.

2011-01-01

171

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

PubMed Central

Background: The success of bonding brackets to enamel with resin bonding systems is negatively affected by contamination with oral fluids such as blood and saliva. The new self-etch primer systems combine conditioning and priming agents into a single application, making the procedure more cost effective. Objective: The purpose of the study was to investigate the effect of moisture, saliva and blood contamination on shear bond strength of orthodontic brackets bonded with conventional bonding system and self-etch bonding system. Materials and Methods: Each system was examined under four enamel surface conditions (dry, water, saliva, and blood), and 80 human teeth were divided into two groups with four subgroups each of 10 according to enamel surface condition. Group 1 used conventional bonding system and Group 2 used self-etched bonding system. Subgroups 1a and 2a under dry enamel surface conditions; Subgroups 1b and 2b under moist enamel surface condition; Subgroups 3a and 3b under saliva enamel surface condition and Subgroup 4a and 4b under blood enamel surface condition. Brackets were bonded, and all the samples were then submitted to a shear bond test with a universal testing machine with a cross head speed of 1mm/sec. Results: The results showed that the contamination reduced the shear bond strength of all groups. In self-etch bonding system water and saliva had significantly higher bond strength when compared to other groups. Conclusion: It was concluded that the blood contamination showed lowest bond strength from both bonding systems. Self-etch bonding system resulted in higher bond strength than conventional bonding system under all conditions except the dry enamel surface. PMID:24678210

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

2014-01-01

172

An Ultracompact Surface Plasmon Polariton-Effect-Based Polarization Rotator  

Microsoft Academic Search

A3 - m-long ultrasmall surface plasmon polariton- effect-based transverse-magnetic (TM) mode to transverse-elec- tric (TE) mode polarization rotator was demonstrated both the- oretically and experimentally. Effective polarization rotation with 11-dB polarization extinction ratio (PER) was achieved in fabri- cated devices. The insertion loss at the transition region was about 11 dB. Surface Plasmon polaritons (SPP) are electromagnetic ex- citations propagating

Jing Zhang; Shiyang Zhu; Huijuan Zhang; Shiyi Chen; Guo-Qiang Lo; Dim-Lee Kwong

2011-01-01

173

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

174

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

175

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

176

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

177

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

178

Comparison of Surface Plasmon Resonance and Localized Surface Plasmon Resonance-based optical fibre sensors  

Microsoft Academic Search

In this work, two of surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR)-based optical fibre sensors have been successfully developed and cross-compared. With one SPR sensor being coated with a thin layer of gold film and the other gold-nanorods (GNRs), forming a LSPR sensor, both sensors are subjected to various refractive index changes. As a result their sensitivities

J. Cao; E. K. Galbraith; T. Sun; K. T. V. Grattan

2011-01-01

179

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

180

Chemical sensors based on surface-confined dendrimers  

SciTech Connect

The use of dendrimers for preparing chemically sensitive interfaces for detecting volatile organic compounds (VOCs) using surface acoustic wave (SAW) device transducers is described. Specifically, the synthesis of the dendrimers and the means by which they are affixed to SAW devices is discussed, followed by a detailed spectroscopic analysis of the surface-confined dendrimers and a discussion of their interaction with different VOCs. Most of these preliminary experiments focus on dendrimer surface modification using benzoylchloride, which leads to phenyl terminal groups linked to the dendrimer via amide groups. The results of this study lead us to conclude that dendrimers: (1) provide general specificity towards classes of functional groups and are therefore suitable for array-based sensing schemes; (2) are intermediate in structure between monolayers and polymers and exhibit the desirable properties of both; (3) can be straightforwardly attached to the surfaces of acoustic wave devices.

Tokuhisa, Hideo; Crooks, R.M. [Texas A& M Univ., College Station, TX (United States). Dept. of Chemistry; Ricco, A.J.; Osbourn, G.C. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

181

Residual-based variational multiscale simulation of free surface flows  

NASA Astrophysics Data System (ADS)

In this work we apply the residual-based variational multiscale method (RB-VMS) to the volume-of-fluid (VOF) formulation of free-surface flows. Using this technique we are able to solve such problems in a Large Eddy Simulation framework. This is a natural extension of our Navier-Stokes solver, which uses the RB-VMS finite element formulation, edge-based data structures, adaptive time step control, inexact Newton solvers and supports several parallel programming paradigms. The VOF interface capturing variable is advected using the computed coarse and fine scales velocity field. Thus, the RB-VMS technique can be readily applied to the free-surface solver with minor modifications on the implementation. We apply this technique to the solution of two problems where available data indicate complex free-surface behavior. Results are compared with numerical and experimental data and show that the present formulation can achieve good accuracy with minor impacts on computational efficiency.

Lins, Erb F.; Elias, Renato N.; Rochinha, Fernando A.; Coutinho, Alvaro L. G. A.

2010-09-01

182

A surface coordination network based on copper adatom trimers.  

PubMed

Surface coordination networks formed by co-adsorption of metal atoms and organic ligands have interesting properties, for example regarding catalysis and data storage. Surface coordination networks studied to date have typically been based on single metal atom centers. The formation of a novel surface coordination network is now demonstrated that is based on network nodes in the form of clusters consisting of three Cu adatoms. The network forms by deposition of tetrahydroxybenzene (THB) on Cu(111) under UHV conditions. As shown from a combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations, all four hydroxy groups of THB dehydrogenate upon thermal activation at 440?K. This highly reactive ligand binds to Cu adatom trimers, which are resolved by high-resolution STM. The network creates an ordered array of mono-dispersed metal clusters constituting a two-dimensional analogue of metal-organic frameworks. PMID:25251167

Bebensee, Fabian; Svane, Katrine; Bombis, Christian; Masini, Federico; Klyatskaya, Svetlana; Besenbacher, Flemming; Ruben, Mario; Hammer, Bjørk; Linderoth, Trolle R

2014-11-17

183

Land surface albedo based on GOES geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Land surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore can be a sensitive indicator of environmental changes. To this end, surface albedo is identified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). NOAA's National Climatic Data Center (NCDC) recently adapted the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for use with GOES data in support of a global albedo initiative led by the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM). SCOPE-CM helps coordinate ECV production responding to GCOS, WMO, and CEOS goals. The GSA algorithm was developed jointly by EUMETSAT and Joint Research Centre (JRC) using a method proposed by Pinty et al. (2000) to determine surface albedo using day-time, cloud-free geostationary observations from a single visible band. For the GOES implementation, raw GOES observations are calibrated using International Satellite Cloud Climatology Project (ISCCP) coefficients. Surface angular anisotropy is determined through the inversion of the GSA radiative transfer model using multiple geostationary images collected over a day under different illumination conditions. The inversion process requires ancillary total column ozone and water vapor values, which are acquired from the 20th Century Reanalysis V2 data set. The GSA algorithm produces a 10-day composite surface albedo map. This product is initially being developed for the years 2000-2003. Product quality is being assessed through comparisons with MODIS products as well as ground-based measurements. NCDC is producing albedo products from both GOES-E (75°W) and GOES-W (135°W). These are being merged with like products from EUMETSAT based on METEOSAT (0° and 63°E) and from JMA based on the Geostationary Meteorological Satellite System (140°E). In the near future, NOAA's Climate Data Record Program will provide the albedo product over the entire GOES period of record (1978-present).

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

2012-12-01

184

A deformable surface model based automatic rat brain extraction method  

Microsoft Academic Search

The extraction of the brain portion of a neurological image is often necessary prior to tissue segmentation or image registration. While MR Imaging studies on the rat have gained much interest lately, an automatic and robust rat brain extraction tool is still lacking. In this paper, we present a deformable surface model-based rat brain extraction method which extends the popular

Jiehua Li; Xiaofeng Liu; Jiachen Zhuo; Rao P. Gullapalli; Jason M. Zara

2011-01-01

185

Effects of enamel deproteinization on bracket bonding with conventional and resin-modified glass ionomer cements.  

PubMed

The objective of this study was to test the effects of enamel deproteinization on bracket bonding with conventional and resin-modified glass ionomer cement (RMGIC). One hundred premolars, extracted for orthodontic reasons, were divided into five groups (n = 20). Group 1 (control): enamel was etched with 35 per cent phosphoric acid, a thin layer of adhesive was applied, and the brackets were bonded with Transbond XT. Group 2: enamel was etched with 10 per cent polyacrylic acid and the brackets were bonded with conventional glass ionomer cement (GIC). Group 3: enamel was treated with 5.25 per cent NaOCl, etched with 10 per cent polyacrylic acid, and the brackets were bonded with conventional GIC. Group 4: enamel was etched with 10 per cent polyacrylic acid and the brackets were bonded with RMGIC. Group 5: enamel was treated with 5.25 per cent NaOCl, etched with 10 per cent polyacrylic acid, and the brackets were bonded with RMGIC. The teeth were stored in distilled water for 24 hours before they were submitted to shear testing. The results demonstrated that bond strength values of group 1 (17.08 ± 6.39 MPa) were significantly higher in comparison with the other groups. Groups 2 (3.43 ± 1.94 MPa) and 3 (3.92 ± 1.57 MPa) presented values below the average recommended in the literature. With regard to adhesive remnant index, the groups in which the enamel was treated with NaOCl showed a behaviour similar to that of the resin composite. It is conclude with enamel treatment with NaOCl increased bonding strength of brackets bonded with GIC and RMGIC, but increased bond strength was not statistically significant when compared to the untreated groups. PMID:22379131

Pereira, Tatiana Bahia Junqueira; Jansen, Wellington Corrêa; Pithon, Matheus Melo; Souki, Bernardo Quiroga; Tanaka, Orlando Motohiro; Oliveira, Dauro Douglas

2013-08-01

186

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

187

Microwave-assisted hydrothermally grown epitaxial ZnO films on Left-Pointing-Angle-Bracket 1 1 1 Right-Pointing-Angle-Bracket MgAl{sub 2}O{sub 4} substrate  

SciTech Connect

In this report, epitaxial ZnO films were grown on Left-Pointing-Angle-Bracket 1 1 1 Right-Pointing-Angle-Bracket MgAl{sub 2}O{sub 4} single crystal substrates using Microwave Assisted Hydrothermal (MAH) method with microwave radiation heating (2.45 GHz) at 90 Degree-Sign C in a short time (within 15 min). Scanning electron microscopy confirms that these films possess smooth surface morphology with fully coalesced grains. In addition, photoluminescence (PL) measurements exhibit strong ultraviolet emission at room temperature, indicating potential applications for short-wave light-emitting photonic devices. The PL properties were improved by a thermal annealing process without generating structural defects. Hall measurements after thermal treatment show the carrier concentration to be of the order of 10{sup 19} cm{sup -3} which is comparable to those grown by conventional solution methods. The MAH method will offer a rapid route to synthesize epitaxial ZnO films with good optical and electrical properties for various applications. - Graphical abstract: FESEM images showing the morphology and cross sectional view of ZnO films grown using microwave assisted hydrothermal method at 90 Degree-Sign C for 30 min. Highlights: Black-Right-Pointing-Pointer Microwave Assisted Hydrothermal (MAH) method was introduced to synthesize epitaxial ZnO films. Black-Right-Pointing-Pointer The films possess smooth surface morphology, fully coalesced grains with high optical properties. Black-Right-Pointing-Pointer It exhibit good electrical properties (carrier concentration 10{sup 19} cm{sup -3}, mobility 19 cm{sup 2}/Vs).

Liew, Laura-Lynn [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Le, Hong Quang, E-mail: lehq@imre.a-star.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link Singapore 117602 (Singapore); Goh, Gregory K.L. [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore)

2012-05-15

188

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

189

Face recognition based on depth maps and surface curvature  

NASA Astrophysics Data System (ADS)

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 also viewpoint invariant. Until recently range data of high enough resolution and accuracy to perform useful curvature calculations on the scale of the human face had been unavailable. Although several researchers have worked on the problem of interpreting range data from curved (although usually highly geometrically structured) surfaces, the main approaches have centered on segmentation by signs of mean and Gaussian curvature which have not proved sufficient in themselves for the case of the human face. This paper details the calculation of principal curvature for a particular data set, the calculation of general surface descriptors based on curvature, and the calculation of face specific descriptors based both on curvature features and a priori knowledge about the structure of the face. These face specific descriptors can be incorporated into many different recognition strategies. A system that implements one such strategy, depth template comparison, giving recognition rates between 80% and 90% is described.

Gordon, Gaile G.

1991-09-01

190

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

191

Laser-Based Transient Surface Acceleration of Thermoelastic Layers  

NASA Astrophysics Data System (ADS)

The removal of particles from elastic substrates has been an important practical problem in the electronics industry especially as the sizes of electronic units shrink. In recent years, there has been an interest in removingsubmicron level particles from surfaces. The use of traditional surface cleaning methods, such as ultrasonically induced fluid flow, vibrational methods, centrifugal techniques, is limited to particles that require surface acceleration lower than 107m/s2. For the effective removal of submicron particles, a higher level surface acceleration is needed since the adhesion forces (mainly van der Waals force for dry surfaces) are related to the particle size and increase approximately linearly as the characteristic radius of small particles that are to be removed decreases. In current work, based on the generalized dynamic theory of thermoelasticity reported, a transfer matrix formulation including the second sound effect is developed for a thermoelastic layer. The transfer matrix for axisymmetric wave propagation in a thermoelastic layer is obtained by adopting a double integral transform approach. The second sound effect is included to eliminate the thermal wave travelling with infinite velocity as predicted by the diffusion heat transfer model, and, consequently, the immediate arrival of waves. Using the current formulation and the periodic systems framework, a transfer function formulation for calculating the accelerations is developed for transient analysis. A double integral transform inversion method is used for transient response calculations. Acceleration levels, sufficient for submicron particle removal, are reported. Various processes such as thermoelastic stresses, surface evaporation, and optical breakdown may be responsible for surface acceleration components and particle removal. In current work, only the surface acceleration due to transient thermoelastic wave propagation is under investigation.

CETINKAYA, CETIN; WU, CUNLI; LI, CHEN

2000-03-01

192

Notching of orthodontic bonding resin to facilitate ceramic bracket debond--an ex vivo investigation.  

PubMed

This ex vivo study assessed the potential of introducing a notch in the bond layer, as a means of facilitating the removal of ceramic brackets. Sixty extracted premolar teeth were divided into three groups of 20 teeth and bonded with Intrigue brackets using Concise chemically-cured adhesive. The bonding technique was modified with groups 1 and 2 by introducing a notch in the bond layer. Group 1 was notched from the gingival aspect, group 2 from the occlusal, and group 3 served as a control. The brackets were removed by applying a shear load from the gingival aspect using an Instron universal testing machine. The mean force to debond was calculated for each group. The results showed that introducing a notch significantly reduced the mean and maximal debond forces. This was confirmed with Weibull analysis with the notched specimens having a higher probability of failure at any force. In addition, ceramic bracket fracture was eliminated. Notching the bonding resin may be helpful in facilitating the removal of ceramic brackets. PMID:9884780

Larmour, C J; McCabe, J F; Gordon, P H

1998-11-01

193

Surface-based determination of the pelvic coordinate system  

NASA Astrophysics Data System (ADS)

In total hip replacement (THR) one technical factor influencing the risk of dislocation is cup orientation. Computer-assisted surgery systems allow for cup navigation in anatomy-based reference frames. The pelvic coordinate system most used for cup navigation in THR is based on the mid-sagittal plane (MSP) and the anterior pelvic plane (APP). From a geometrical point of view, the MSP can be considered as a mirror plane, whereas the APP can be considered as a tangent plane comprising the anterior superior iliac spines (ASIS) and the pubic tubercles. In most systems relying on the pelvic coordinate system, the most anterior points of the ASIS and the pubic tubercles are selected manually. As manual selection of landmark points is a tedious, time-consuming and error-prone task, a surface-based approach for combined MSP and APP computation is presented in this paper: Homologous points defining the MSP and the landmark points defining the APP are selected automatically from surface patches. It is investigated how MSP computation can benefit from APP computation and vice versa, and clinical perspectives of combined MSP and APP computation are discussed. Experimental results on computed tomography data show that the surface-based approach can improve accuracy.

Fieten, Lorenz; Eschweiler, Jörg; Heger, Stefan; Kabir, Koroush; Gravius, Sascha; de la Fuente, Matías; Radermacher, Klaus

2009-02-01

194

Testing smooth surface characteristics based on thermal infrared polarization  

NASA Astrophysics Data System (ADS)

A novel optical method was provided to test the sample surface using a thermal polarimeter. The polarimeter consists of a rotary polarization filter and a thermal imaging system that is based on an uncooled focal plane array (UFPA) in long wave infrared (LWIR, 8~12?m) band. The thermal infrared polarization images of a Vernier caliper head were taken by a rotary polarizing filter at angles of 0°, 60°, 120° degrees. These images were saved into a computer and were calculated with Stokes parameter formulas to produce digital images of Stokes parameters I, Q and U, degree of linear polarization and direction of polarization. These images clearly show the difference between different areas of Vernier caliper, and this difference is not obtainable from the intensity images. Experimental results show that the introduced method can extract surface roughness information from thermal images and can distinguish different surface characteristics quickly.

Sun, Li; Wang, Zhen; Hong, Jin; Qiao, Yan-li; Chen, Yi-qiong

2007-12-01

195

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

196

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

197

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

198

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

199

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

200

Roughness-based Superhydrophobic Surfaces: Fundamentals and Future Directions  

NASA Astrophysics Data System (ADS)

Superhydrophobicity of rough surfaces has attracted global interest through the past decade. There are naturally occurring instances of such surfaces, e.g., lotus leaves, which led to the popular term ``lotus effect.'' Numerous applications in wide ranging areas such as drag reduction, self-cleaning, heat exchangers, energy conversion, condensation, anti-icing, textile, desalination, etc., are being explored by researchers worldwide. The signature configuration for superhydrophobicity has been ``bead-like'' drops on rough surfaces that roll-off easily. This becomes possible if the liquid does not impale the roughness grooves, and if the contact angle hysteresis is low. Finding appropriate surface roughness is therefore necessary. A thermodynamic framework to enable analysis of this problem will be presented. It will be noted that the success of rough superhydrophobic substrates relies on the presence of gas pockets in the roughness grooves underneath the liquid. These gas pockets could be those of air from the surrounding environment. Current design strategies rely on the availability of air. However, if the rough substrates are fully submerged in the liquid then the trapped air in the roughness grooves may not be sustained. A design approach based on sustaining a vapor phase of the liquid itself in the roughness grooves, instead of relying on the presence of air, will be presented. The resulting surfaces, referred to as vapor stabilizing substrates, are deemed to be robust against wetting transition even if no air is present. Applications of this approach include low drag surfaces, nucleate boiling at dramatically low superheats, among others. The concept can be generalized to other transitions on the phase diagram, thus enabling the design of rough surfaces for phase manipulation in general.

Patankar, Neelesh

2011-11-01

201

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

202

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

203

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

2014-12-01

204

Point Based Rendering of Implicit 4Dimensional Surfaces  

Microsoft Academic Search

We present a point based rendering algorithm that uses hyper-cubes to perform spatial subdivision in a 4D volume. A 4D function interval exclusion test is used to speed up the rendering of 4D Implicit surfaces in this hyper-volume. A 4D orthonormal basis function is used to define a 4D camera, which projects isometric or perspective views onto a plane in

Ronald J. Balsys; Kevin G. Suffern

2007-01-01

205

Advanced construction management for lunar base construction - Surface operations planner  

NASA Technical Reports Server (NTRS)

The study proposes a conceptual solution and lays the framework for developing a new, sophisticated and intelligent tool for a lunar base construction crew to use. This concept integrates expert systems for critical decision making, virtual reality for training, logistics and laydown optimization, automated productivity measurements, and an advanced scheduling tool to form a unique new planning tool. The concept features extensive use of computers and expert systems software to support the actual work, while allowing the crew to control the project from the lunar surface. Consideration is given to a logistics data base, laydown area management, flexible critical progress scheduler, video simulation of assembly tasks, and assembly information and tracking documentation.

Kehoe, Robert P.

1992-01-01

206

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

207

Development of surface-plasmon-resonance-based immunoassay for cephalexin  

NASA Astrophysics Data System (ADS)

The public concern surrounding antibiotic contamination in food and food products has made it imperative to develop analytical methods for their detection. Polyclonal antibodies and protein-hapten conjugates to cephalexin were used in the development of a surface plasmon resonance (SPR)-based inhibition immunoassay to cephalexin. A conjugate consisting of cephalexin-bovine serum albumin (BSA) was immobilised on the dextran gel surface. Dissociation between the antibody and antigen was easily achieved with 10 mmol l-1 NaOH and was very reproducible. Standards of free hapten were prepared and premixed with antibody and, after a suitable incubation time, passed over the surface of the chip with the protein-hapten conjugate immobilised. The hapten in solution inhibited the binding of antibody to the surface resulting in higher response units of antibody bound at lower concentrations of free drug. Model inhibition immunoassays to cephalexin were developed in PBS and spiked milk samples. These assays had detection ranges between 4.88 to 2,500 ng ml-1 and 244 to 3,900 ng ml-1, respectively, with reproducible results.

Dillon, Paul P.; Daly, Stephen J.; Browne, Johnathan; Manning, Bernadette M.; O'Kennedy, Richard; van Amerongen, Aart

2003-03-01

208

GPGPU-based surface inspection from structured white light  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

209

26 CFR 1.63-1 - Change of treatment with respect to the zero bracket amount and itemized deductions.  

Code of Federal Regulations, 2010 CFR

...treatment with respect to the zero bracket amount and itemized deductions...treatment with respect to the zero bracket amount and itemized deductions...taxable year. A taxable year of one spouse corresponds to a taxable...year. If the taxable year of one spouse ends with death,...

2010-04-01

210

arXiv:math.QA/0304316v228Sep2003 Rankin-Cohen Brackets and the Hopf  

E-print Network

deformations. Introduction In [1] H. Cohen constructed a collection of bilinear operations on functionsarXiv:math.QA/0304316v228Sep2003 Rankin-Cohen Brackets and the Hopf Algebra of Transverse Geometry to extend the Rankin-Cohen brackets from modular forms to modular Hecke al- gebras. More generally, our

Connes, Alain

211

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

212

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

213

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

214

Airborne LIDAR borsight error calibration based on surface coincide  

NASA Astrophysics Data System (ADS)

Light Detection and Ranging (LIDAR) is a system which can directly collect three-dimensional coordinate information of ground point and laser reflection strength information. With the wide application of LIDAR system, users hope to get more accurate results. Boresight error has an important effect on data accuracy and thus, it is thought that eliminating the error is very important. In recent years, many methods have been proposed to eliminate the error. Generally, they can be categorized into tie point method and surface matching method. In this paper, we propose another method called try value method based on surface coincide that is used in actual production by many companies. The method is simple and operable. Further, the efficacy of the method was demonstrated by analyzing the data from Zhangye city.

Yuan, Fangyan; Li, Guoqing; Zuo, Zhengli; Li, Dong; Qi, Zengying; Qiu, Wen; Tan, Junxiang

2014-03-01

215

Surface skeleton generation based on 360-degree profile scan  

NASA Astrophysics Data System (ADS)

A rapid prototyping method is invented, which works on a specific data structure produced by an optical metrology technique: 360-degree surface profile scanning. A computer algorithm takes an object profile data, restructure the format, generate horizontal and vertical ribs, lay out the ribs on a 2D canvas and output the geometries to a file format compatible with laser cutters. A laser cutting machine is subsequently used to cut all the ribs from sheet materials. Then, the ribs are manually assembled based on computer-generated assembly codes. Through this process, the original object's 3D surface can be prototyped rapidly at an arbitrary scale, which may well exceed the working dimension of the laser cutter.

Chen, Lujie; Sass, Lawrence; Sung, Woong Ki; Noel, Vernelle

2013-05-01

216

Wide steering angle microscanner based on curved surface  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

217

Silicon nanohybrid-based surface-enhanced Raman scattering sensors.  

PubMed

Nanomaterial-based surface-enhanced Raman scattering (SERS) sensors are highly promising analytical tools, capable of ultrasensitive, multiplex, and nondestructive detection of chemical and biological species. Extensive efforts have been made to design various silicon nanohybrid-based SERS substrates such as gold/silver nanoparticle (NP)-decorated silicon nanowires, Au/Ag NP-decorated silicon wafers (AuNP@Si), and so forth. In comparison to free AuNP- and AgNP-based SERS sensors, the silicon nanohybrid-based SERS sensors feature higher enhancement factors (EFs) and excellent reproducibility, since SERS hot spots are efficiently coupled and stabilized through interconnection to the semiconducting silicon substrates. Consequently, in the past decade, giant advancements in the development of silicon nanohybrid-based SERS sensors have been witnessed for myriad sensing applications. In this review, the representative achievements related to the design of high-performance silicon nanohybrid-based SERS sensors and their use for chemical and biological analysis are reviewed in a detailed way. Furthermore, the major opportunities and challenges in this field are discussed from a broad perspective and possible future directions. PMID:25243935

Wang, Houyu; Jiang, Xiangxu; Lee, Shuit-Tong; He, Yao

2014-11-01

218

Surface sensitivity of straight long-range surface plasmon waveguides for attenuation-based biosensing  

NASA Astrophysics Data System (ADS)

The sensing performance of straight long-range surface plasmon waveguides consisting of a thin gold stripe embedded in Cytop is explored theoretically as a function of the metal stripe cross-sectional dimensions and the length of the sensing channel, and as a function of the sensing medium refractive index. The surface sensitivity and detection limit of such waveguides for attenuation-based biosensing are assessed. We find that changes in coupling efficiency between the sensing waveguide and the access waveguides, and changes in attenuation constant, due to adlayer formation, can contribute additively to the sensing performance. We observed a trade-off between the insertion loss and the change in insertion loss occurring during sensing. Optimum designs leading to compact, sensitive, and cost-effective biosensors are reported.

Wong, Wei Ru; Mahamd Adikan, Faisal Rafiq; Berini, Pierre

2014-08-01

219

On the use of projectors for Hamiltonian systems and their relationship with Dirac brackets  

E-print Network

Chandre1 , L de Guillebon1 , A Back1 , E Tassi1 and P J Morrison2 1 Centre de Physique Th´eorique, CNRS system with quasineutrality. hal-00696091,version1-10May2012 #12;Dirac projectors for Hamiltonian systems 2 1. Introduction We consider an arbitrary Poisson bracket of a Poisson algebra of functionals

Boyer, Edmond

220

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

221

J. Ramanujan Math. Soc. 24, No.3 (2009) 213233 Rankin-Cohen brackets on quasimodular forms  

E-print Network

Abstract. We give the algebra of quasimodular forms a collection of Rankin-Cohen operators. These operatorsJ. Ramanujan Math. Soc. 24, No.3 (2009) 213­233 Rankin-Cohen brackets on quasimodular forms Franc extend those defined by Cohen on modular forms and, as for modular forms, the first of them provides

Royer, Emmanuel

222

hal-00009145,version2-12Apr2008 RANKIN-COHEN BRACKETS ON QUASIMODULAR  

E-print Network

AND EMMANUEL ROYER Abstract. We give the algebra of quasimodular forms a collection of Rankin-Cohen operatorshal-00009145,version2-12Apr2008 RANKIN-COHEN BRACKETS ON QUASIMODULAR FORMS FRANC¸OIS MARTIN. Rankin-Cohen operators are useful for proving arithmetical identities. In particular, we explain why

Boyer, Edmond

223

Treatment of Longitudinal Epiphyseal Bracket by Excision and Polymethylmethacrylate Insertion at the Preossified Disease Stage.  

PubMed

Longitudinal epiphyseal bracket is a rare ossification anomaly involving the tubular bones of the hand or foot that have a proximal epiphysis, which becomes deformed as a result of the bracket. Untreated, the deformity becomes worse with age, because longitudinal growth cannot occur. The present report discusses the use of polymethylmethacrylate at the preossified disease stage in 2 patients with first metatarsal involvement. A medical record and radiographic review was performed for 2 children (3 feet), aged 1 year and 2 years and 5 months, who were treated with insertion of polymethylmethacrylate after excision of the aberrant epiphyseal bracket. Two different radiographic parameters (i.e., the intraosseous angulation and the metadiaphyseal length index) were used to measure the effect of treatment on the subsequent longitudinal growth of the metatarsals. An excellent clinical result after a long follow-up period was observed in 2 feet, and a good result was documented in 1 foot, which developed hallux valgus angulation. The use of polymethylmethacrylate as an interposition material after excision of the aberrant metatarsal epiphyseal bracket appeared to be an effective method of treatment during the preossified first stage of the disease, despite the general recommendation to use a cement spacer during the third ossified stage. Normal longitudinal growth of the metatarsals was noted without complications or risk of deformity recurrence. PMID:25441856

Bor, Noam; Rozen, Nimrod; Rubin, Guy

2014-10-23

224

The Jacobi identity for graded-commutative variational Schouten bracket revisited  

NASA Astrophysics Data System (ADS)

This short note contains an explicit proof of the Jacobi identity for variational Schouten bracket in ?2-graded commutative setup; an extension of the reasoning and assertion to the noncommutative geometry of cyclic words (see [1]) is immediate. The reasoning refers to the product bundle geometry of iterated variations (see [2]); no ad hoc regularizations occur anywhere in this theory.

Kiselev, A. V.

2014-12-01

225

Effects of different chlorhexidine pretreatments on adhesion of metal brackets in vitro  

PubMed Central

Objective To investigate the effect of chlorhexidine applications in various forms and concentrations on adhesion and failure modes of metal brackets in vitro. Material and methods Ninety bovine enamel specimens were allocated to six groups (n=15). Metal brackets were bonded on all specimens after chlorhexidine pre-treatments forming the following groups: (1) untreated specimens (control); (2) 40% varnish (EC40, Biodent BV, Netherlands), remnants removed with brushing mimicking patient cleaning; (3) 40% varnish (EC40), remnants removed with brushing mimicking professional cleaning; (4) 1% varnish (Cervitec Plus, Ivoclar vivadent, Schaan, Liechtenstein), remnants not removed; (5) brushed with% 1 gel (Corsodyl, GlaxoSmithKline, Münchenbuchsee, Germany), remnants not removed; (6) immersed in 0.07% mouthrinse (Corsodyl, GlaxoSmithKline, Münchenbuchsee, Germany), remnant not rinsed. Debonding of brackets was performed using a universal testing machine. Data were analysed using one-way ANOVA and post-hoc Scheffé test. Results Group 4 performed significantly inferior than all the other groups and the control. Group 4 presented the highest number of adhesive failures at the enamel-resin interface whereas in other groups no failures at adhesive-resin interface was observed. Conclusion Presence of chlorhexidine varnish prior to bracket bonding adversely affects adhesion. Concentration of chlorhexidine pre-treatment has no influence on shear bond strength. PMID:23273111

2012-01-01

226

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

227

AdaptiviTree: Adaptive Tree Visualization for Tournament-Style Brackets  

E-print Network

representation, but also allows overlays that display predictions as well as other statistics. We describe predictions on a tournament bracket that defines which competitors play each other and how they proceed toward and to compare predictions made by multiple players. This is often a complex sensemaking task. The classic

Rajamani, Sriram K.

228

Effect of argon laser irradiation on shear bond strength of orthodontic brackets: An in vitro study  

Microsoft Academic Search

Argon lasers, due to their significant time savings over conventional curing lights, are being investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel. The purpose of this study was to evaluate the effects of argon laser irradiation on bond strength at 3 different laser energies (200, 230, and

Travis Q. Talbot; Richard J. Blankenau; Mark E. Zobitz; Amy L. Weaver; Christine M. Lohse; Joe Rebellato

2000-01-01

229

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

230

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

231

Osteoconductive protamine-based polyelectrolyte multilayer functionalized surfaces.  

PubMed

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; Hammond, Paula T

2011-10-01

232

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

233

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

234

Remote surface water monitoring radio based telemetry system  

SciTech Connect

The Environmental Protection Department of EG&G Rocky Flats has designed and developed a unique Remote Surface Water Monitoring System using radio telemetry hardware and computer control software. The system is based on new technologies in microelectronics and envirorunental monitoring sensors. An engineering team, headed up by the Surface Water Division at EG&G, has proven that with careful evaluation of new technologies and hardware components, a reliable, cost effective and graphical user interface (GUI) system can be designed and installed. The network utilizes standard industrial control hardware and off-the-shelf components in order to meet several time requirements outlined by an Interagency Agreement (IAG) between the Department of Energy, the U.S. Environmental Protection Agency, and state and local authorities. In addition, the system had to meet tight environmental specifications and procedures. The Rocky Flats Plant is part of the U.S. Department of Energy Weapons Complex and is located near the Denver metropolitan area. The plant is required by law, and Interagency Agreement, to maintain strict environmental standards for surface water monitoring and discharge characteristics, including the requirement for utilization of best available technology.

Goodwin, W.L.; Baxter, D.

1993-02-01

235

Ring resonator-based surface emitting quantum cascade lasers  

NASA Astrophysics Data System (ADS)

We describe the design, simulation, fabrication and operation of ring cavity surface emitting lasers (RCSEL) based on quantum cascade structures for the midinfrared (MIR) and terahertz (THz) spectral range. MIR RCSELs facilitate an enhancement of optical power and a reduction in threshold current density, as compared to Fabry-Perot (FP) lasers. In continuous wave operation the maximum temperature of ring based devices is 50 K higher than in FP emitters. Also in THz QCLs a twofold increase in radiation efficiency is observed when compared to FP lasers. The emitters exhibit a robust single-mode operation around 8 ?m and 3.2 THz, with a side mode suppression ratio of 30 dB. The ring-shaped resonator forms symmetric far-field profiles, represented by a lobe separation of ~1.5° and ~15° for MIR and THz lasers, respectively.

Mujagic, E.; Schwarzer, C.; Nobile, M.; Detz, H.; Ahn, S.; Klang, P.; Andrews, A. M.; Schrenk, W.; Deutsch, C.; Unterrainer, K.; Chen, J.; Gmachl, C.; Strasser, G.

2010-02-01

236

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

PubMed Central

Background: Reduced time and appropriate bond strength of brackets is one of the most important aspects of orthodontic treatments. Prolonged halogen light curing for bonding of brackets is undesirable, so the purpose of this study was to compare the shear bond strength of brackets bonded with halogen light and plasma arc system. Materials and Mehods: This was an experimental in vitro study. A total of 60 intact premolar teeth were collected and divided into four groups. Stainless steel orthodontic brackets were bonded to them. In groups 1 and 2, curing was done using halogen light given for 20 seconds from two and four angles. In groups 3 and 4, curing was carried out using the plasma arc system for 6 seconds from two and four angles. The shear bond strength was recorded by Instron. The statistics of ANOVA, Tukey's test, and T-test were used in data analysis. Results: There was a statistically significant difference in shear bond strength among the four groups (P = 0.043) and between group 1 with group 2 (P = 0.035). Yet, there was no statistically significant difference between brackets bonded with plasma arc and those bonded with halogen light or between the two groups of plasma arc. Conclusion: Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles. PMID:23087739

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

2012-01-01

237

Graphene-based textured surface by pulsed laser deposition as a robust platform for surface enhanced Raman scattering applications  

E-print Network

1 Graphene-based textured surface by pulsed laser deposition as a robust platform for surface scattering (SERS)-active substrate based on gold nanoparticles-decorated few-layer (fl) graphene grown by pulsed laser deposition. Diamond-Like Carbon film has been converted to fl-graphene after thermal

Boyer, Edmond

238

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

239

Micro-and nanostructured silicon-based superomniphobic surfaces.  

PubMed

We report on the fabrication of silicon nanostructured superhydrophobic and superoleophobic surfaces also called "superomniphobic" surfaces. For this purpose, silicon interfaces with different surface morphologies, single or double scale structuration, were investigated. These structured surfaces were chemically treated with perfluorodecyltrichlorosilane (PFTS), a low surface energy molecule. The morphology of the resulting surfaces was characterized using scanning electron microscopy (SEM). Their wetting properties: static contact angle (CA) and contact angle hysteresis (CAH) were investigated using liquids of various surface tensions. Despite that we found that all the different morphologies display a superhydrophobic character (CA>150° for water) and superoleophobic behavior (CA ? 140° for hexadecane), values of hysteresis are strongly dependent on the liquid surface tension and surface morphology. The best surface described in this study was composed of a dual scale texturation i.e. silicon micropillars covered by silicon nanowires. Indeed, this surface displayed high static contact angles and low hysteresis for all tested liquids. PMID:24370432

Nguyen, Thi Phuong Nhung; Boukherroub, Rabah; Thomy, Vincent; Coffinier, Yannick

2014-02-15

240

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

241

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

242

A response surface methodology based damage identification technique  

NASA Astrophysics Data System (ADS)

Response surface methodology (RSM) is a combination of statistical and mathematical techniques to represent the relationship between the inputs and outputs of a physical system by explicit functions. This methodology has been widely employed in many applications such as design optimization, response prediction and model validation. But so far the literature related to its application in structural damage identification (SDI) is scarce. Therefore this study attempts to present a systematic SDI procedure comprising four sequential steps of feature selection, parameter screening, primary response surface (RS) modeling and updating, and reference-state RS modeling with SDI realization using the factorial design (FD) and the central composite design (CCD). The last two steps imply the implementation of inverse problems by model updating in which the RS models substitute the FE models. The proposed method was verified against a numerical beam, a tested reinforced concrete (RC) frame and an experimental full-scale bridge with the modal frequency being the output responses. It was found that the proposed RSM-based method performs well in predicting the damage of both numerical and experimental structures having single and multiple damage scenarios. The screening capacity of the FD can provide quantitative estimation of the significance levels of updating parameters. Meanwhile, the second-order polynomial model established by the CCD provides adequate accuracy in expressing the dynamic behavior of a physical system.

Fang, S. E.; Perera, R.

2009-06-01

243

Plasma-based physical vapor deposition surface engineering processes  

NASA Astrophysics Data System (ADS)

Plasma-based physical vapor deposition (PVD) process developments occurring over the past few decades now allow the production of tribological coatings with properties which were previously unachievable. These new coatings will be critical in the creation of new products with improved functionality and performance, which will have a dramatic impact on, for example, their operating efficiency and lifetime. The key pioneers behind these PVD developments are discussed here, together with some significant process innovations. The latter include ionization-enhancing systems, such as thermionic assistance and arc evaporation, as well as unbalanced magnetron sputtering and magnetic plasma confinement. These developments have provided the impetus behind the recent growth in the technology field which we now know as surface engineering, and the recognition that surfaces provide the functionality and durability for almost all engineered products. Vacuum plasma technologies can thus be regarded as critical, not only for functional devices and thin film applications (for which their importance was previously most recognized), but also for structural product applications; they will thus underpin the entire spectrum of manufacturing industry.

Matthews, Allan

2003-09-01

244

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

245

Surface plasmon resonance imaging biosensor based on silicon photodiode array  

NASA Astrophysics Data System (ADS)

The detection limit of surface plasmon resonance imaging (SPRI) biosensor is constrained in part by the SPR biochip and in part by the resolution of the optical intensity of detecting instruments. In this paper, silicon photodiode is proposed as the optical intensity detecting element instead of the traditionally used charge coupled device (CCD), combining with high resolution analog/digital converter, this method can efficiently reduce the cost and increase the sensitivity of the SPRI system while keeping its virtue of multiple channels real time detecting. Based on this method, An SPRI experimental system with two channels is designed and the optical intensity of each channel is detected by a photodiode. By carrying out testing experiments using sucrose solution with different concentrations (corresponding to different refractive index), the system sensitivity of 10-6 refractive index unit (RIU) is obtained.

Yin, Shaoyun; Sun, Xiuhui; Deng, Qiling; Xia, Liangping; Du, Chunlei

2010-11-01

246

bFGF immunochemical detection based on surface plasmon resonance  

NASA Astrophysics Data System (ADS)

Surface Plasmon Resonance (SPR) is very sensitive to the change of the refractive index of the dielectric medium on metallic films. Without labeling and purification the samples can quickly, real-timely and dynamically analyze bio-molecular interactions. The biochip detection system based on SPR has been established to detect the immunoreactions for the prepared bFGF protein chip, including the reaction between bFGF antigen and antibody, between bFGF antibody and antibody's antibody respectively. After the immunoreactions occur on sample arrays the refractive index as well as the resonant angle will increase. The reflected light images of the chips taken by the CCD camera can determine the happening of the immunoreactions on the probes of the chips and the existing of substances that are needed to be detected. SPR system can analyze qualitatively and quantitatively.

Li, Ying; Zhong, Jingang; Zhang, Yonglin; Tang, Yong

2009-11-01

247

Frequency Selective Surface Based Bandpass Filter for THz Communication System  

NASA Astrophysics Data System (ADS)

In this work, a band pass filter based on frequency selective surface (FSS) is presented. The resonance of the FSS is achieved by perforating slot type ring structure on an Aluminum layer. To ensure adequate mechanical strength, this structure is again supported by a dielectric layer. The physical dimensions of the FSS, i.e. ring radius, slot width, cell dimension and width of the layers all are responsible for the resonance behavior. In its electrical equivalent circuit, these dimensions act as inductor and capacitor. The center frequency of the designed filter is at 0.16 THz with a -3 dB bandwidth of 18 GHz. This filter can be utilized as a part of any THz communication system to achieve application specific frequency discrimination. The simulation has been carried by using commercial software-CST Microwave Studio. The performance of the fabricated FSS is evaluated by Microwave Vector Network Analyzer.

Das, Subrata; Reza, Khan Mamun; Habib, Md. Ahsan

2012-11-01

248

Quantifying modern biomes based on surface pollen data in China  

NASA Astrophysics Data System (ADS)

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

Chen, Yu; Ni, Jian; Herzschuh, Ulrike

2010-12-01

249

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

SciTech Connect

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

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

2004-04-01

250

Effects of a fluoride-containing casein phosphopeptide-amorphous calcium phosphate complex on the shear bond strength of orthodontic brackets.  

PubMed

The purpose of this study was to investigate the effects of enamel pre-treatment with a new fluoride-containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) complex on the shear bond strength (SBS) of brackets bonded with etch-and-rinse or self-etching adhesive systems. The material comprised 66 extracted human premolars randomly divided into six equal groups with respect to the enamel pre-treatment and adhesive system employed: 1. No pre-treatment and brackets bonded with the etch-and-rinse adhesive system (Transbond XT). 2. Pre-treatment with fluoride-containing CPP-ACP paste (MI Paste Plus) and Transbond XT. 3. Pre-treatment with non-fluoride CPP-ACP paste (MI Paste) and Transbond XT.4. No pre-treatment and brackets bonded with the self-etching adhesive system (Transbond Plus). 5 and 6. Enamel pre-treated as for groups 2 and 3, respectively, and the Transbond Plus. Bonded specimens were subjected to thermal cycling (×1000) before SBS testing. The residual adhesive on the enamel surface was evaluated after debonding with the adhesive remnant index (ARI). Data evaluation was made using one-way analysis of variance and Tukey test for SBS results, and Kruskal-Wallis test for ARI results. The results showed that enamel pre-treatment with either fluoride or non-fluoride CPP-ACP paste had no significant effect on the SBS of the self-etching adhesive system (P > 0.05). Enamel pre-treatment with non-fluoride CPP-ACP in group 3 significantly reduced the SBS of the etch-and-rinse adhesive (P < 0.001), while pre-treatment with fluoride-containing CPP-ACP paste (groups 2 and 5) did not affect debonding values (P > 0.05). The fluoride-containing CPP-ACP did not compromise the SBS of brackets bonded with the tested etch-and-rinse and self-etching systems, but its non-fluoride version significantly decreased the SBS of the etch-and-rinse adhesive system. PMID:21317209

Cehreli, Sevi Burçak; Sar, Cagla; Polat-Özsoy, Omür; Unver, Bahtiyar; Ozsoy, Serhat

2012-04-01

251

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

252

Satellite-based estimates of Antarctic surface meltwater fluxes  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

253

Are self-ligating brackets related to less formation of Streptococcus mutans colonies? A systematic review  

PubMed Central

Objective To verify, by means of a systematic review, whether the design of brackets (conventional or self-ligating) influences adhesion and formation of Streptococcus mutans colonies. Methods Search strategy: four databases (Cochrane Central Register of Controlled Trials, Ovid ALL EMB Reviews, PubMed and BIREME) were selected to search relevant articles covering the period from January 1965 to December 2012. Selection Criteria: in first consensus by reading the title and abstract. The full text was obtained from publications that met the inclusion criteria. Data collection and analysis: Two reviewers independently extracted data using the keywords: conventional, self-ligating, biofilm, Streptococcus mutans, and systematic review; and independently evaluated the quality of the studies. In case of divergence, the technique of consensus was adopted. Results The search strategy resulted in 1,401 articles. The classification of scientific relevance revealed the high quality of the 6 eligible articles of which outcomes were not unanimous in reporting not only the influence of the design of the brackets (conventional or self-ligating) over adhesion and formation of colonies of Streptococcus mutans, but also that other factors such as the quality of the bracket type, the level of individual oral hygiene, bonding and age may have greater influence. Statistical analysis was not feasible because of the heterogeneous methodological design. Conclusions Within the limitations of this study, it was concluded that there is no evidence for a possible influence of the design of the brackets (conventional or self-ligating) over colony formation and adhesion of Streptococcus mutans. PMID:24713561

do Nascimento, Leonard Euler Andrade Gomes; de Souza, Margareth Maria Gomes; Azevedo, Angela Rita Pontes; Maia, Lucianne Cople

2014-01-01

254

Comparison of frictional forces between aesthetic orthodontic coated wires and self-ligation brackets  

PubMed Central

Objective The purpose of this study was to evaluate the clinical efficacy of polymer- and rhodium-coated wires compared to uncoated wires by measuring the frictional forces using self-ligation brackets. Methods 0.016-inch nickel titanium (NiTi) wires and 0.017 × 0.025-inch stainless steel (SS) wires were used, and the angulations between the brackets and wires were set to 0°, 5°, and 10°. Upper maxillary premolar brackets (Clippy-C®) with a 0.022-inch slot were selected for the study and a tensile test was performed with a crosshead speed of 5 mm/min. The maximum static frictional forces and kinetic frictional forces were recorded and compared. Results The maximum static frictional forces and the kinetic frictional forces of coated wires were equal to or higher than those of the uncoated wires (p < 0.05). The maximum static frictional forces of rhodium-coated wires were significantly higher than those of polymer-coated wires when the angulations between the brackets and wires were set to (i) 5° in the 0.016-inch NiTi wires and (ii) all angulations in the 0.017 × 0.025-inch SS wires (p < 0.05). The kinetic frictional forces of rhodium-coated wires were higher than those of polymer-coated wires, except when the angulations were set to 0° in the 0.016-inch NiTi wires (p < 0.05). Conclusions Although the frictional forces of the coated wires with regards to aesthetics were equal to or greater than those of the uncoated wires, a study under similar conditions regarding the oral cavity is needed in order to establish the clinical implications. PMID:25133130

Kim, Yunmi; Cha, Jung-Yul; Hwang, Chung-Ju; Tahk, Seon Gun

2014-01-01

255

Effectiveness of varnish with CPP-ACP in prevention of caries lesions around orthodontic brackets: an OCT evaluation.  

PubMed

Summary OBJECTIVE: To evaluate the in vitro efficiency of applying varnish containing casein phosphopeptide (CPP) and amorphous calcium phosphate (ACP) in prevention of caries lesions around orthodontic brackets. PMID:24997026

Pithon, Matheus M; Dos Santos, Mariana J; Andrade, Camilla S S; Leão Filho, Jorge César B; Braz, Ana Karla S; de Araujo, Renato E; Tanaka, Orlando M; Fidalgo, Tatiana K S; Dos Santos, Adrielle M; Maia, Lucianne C

2014-07-01

256

Comparison of friction produced by two types of orthodontic bracket protectors  

PubMed Central

Introduction Fixed orthodontic appliances have been regarded as a common causative factor of oral lesions. To manage soft tissue discomfort, most orthodontists recommend using a small amount of utility wax over the brackets in order to alleviate trauma. This in vitro study aimed at evaluating friction generated by two types of bracket protectors (customized acetate protector [CAP] and temporary resin protector [TRP]) during the initial stages of orthodontic treatment. Methods An experimental model (test unit) was used to assess friction. In order to measure the friction produced in each test, the model was attached to a mechanical testing machine which simulated maxillary canines alignment. Intergroup comparison was carried out by one-way ANOVA with level of significance set at 5%. Results The friction presented by the TRP group was statistically higher than that of the control group at 6 mm. It was also higher than in the control and CAP groups in terms of maximum friction. Conclusion The customized acetate protector (CAP) demonstrated not to interfere in friction between the wire and the orthodontic bracket slot. PMID:24713564

Mendonça, Steyner de Lima; Praxedes Neto, Otávio José; de Oliveira, Patricia Teixeira; dos Santos, Patricia Bittencourt Dutra; Pinheiro, Fábio Henrique de Sá Leitão

2014-01-01

257

Evaluation of the effects of CO 2 laser on debonding of orthodontics porcelain brackets vs. the conventional method  

Microsoft Academic Search

Debonding of ceramic brackets due to their high bond strength and low fracture toughness is one of the clinician’s complications.\\u000a The purpose of this study is to evaluate the effect of a laser on shear bond strength, site of debonding, and ARI index during\\u000a debonding of ceramic brackets and then compare it to the conventional method used for this procedure.

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

2011-01-01

258

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

259

Inverse offset method for adaptive cutter path generation from point-based surface  

Microsoft Academic Search

The inverse offset method (IOM) is widely used for generating cutter paths from the point- based surface where the surface is characterised by a set of surface points rather than parametric polynomial surface equations. In the IOM, cutter path planning is carried out by specifying the grid sizes, called the step-forward and step-interval distances respectively in the forward and transverse

Prasenjit Kayal

260

Roughness-Adaptive 3-D Watermarking Based on Masking Effect of Surface Roughness  

Microsoft Academic Search

We present a method to improve watermark robustness by exploiting the masking effect of surface roughness on watermark visibility. Our idea is to adapt watermark strength to local surface roughness based on the knowledge that human eyes are less sensitive to changes on a rougher surface patch than those on a smoother surface. In order to quantify human sensitivity to

Kwangtaek Kim; Mauro Barni; Hong Z. Tan

2010-01-01

261

Weak bonding of Zn in an Al-based approximant based on surface measurements  

Microsoft Academic Search

We have studied two surfaces of a new Al–Pd–Zn approximant using mass spectrometry, X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM). Zn is bonded weakly in this approximant, perhaps as weakly as in elemental Zn. This is based upon three observations: (1) the low vapor pressure of Zn above the approximant (detectable in the gas phase at 600?K), (2)

Chad D. Yuen; Baris Unal; Dapeng Jing; Patricia A. Thiel

2011-01-01

262

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

263

Continuous integrable systems with multi-Poisson brackets  

SciTech Connect

For discrete finite systems, it is known that the zero Nijenhuis tensor condition can be used to explicitly construct conserved quantities in involution. Although the same method is not directly generalizable for continuous systems because of the divergence problem, the difficulty can be overcome with some minor modifications. In this way, various cases of KdV, nonlocal KdV, continuous Toda lattice, Kac--Moody hierarchy, and a model based upon a {ital W}{sub 3}-algebra systematically by the same technique can be discussed.

Okubo, S. (Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States))

1992-06-01

264

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

265

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

266

The string topology BV algebra, Hochschild cohomology and the Goldman bracket on surfaces  

Microsoft Academic Search

In 1999 Chas and Sullivan discovered that the homology H_*(LX) of the space of free loops on a closed oriented smooth manifold X has a rich algebraic structure called string topology. They proved that H_*(LX) is naturally a Batalin-Vilkovisky (BV) algebra. There are several conjectures connecting the string topology BV algebra with algebraic structures on the Hochschild cohomology of algebras

Dmitry Vaintrob

2007-01-01

267

Design of anticoagulant surfaces based on cellulose nanocrystals.  

PubMed

The anticoagulant activity of surfaces decorated with cellulose nanocrystals (CNCs) prepared via sulfuric acid hydrolysis, is explored. Such surfaces bear a high amount of negatively charged sulfate groups, which mimic the naturally occurring anticoagulant heparin in terms of charge density. It is demonstrated that CNC decorated surfaces significantly enhance the coagulation times of blood plasma and whole blood as proven by QCM-D and simple clotting tests. PMID:25225660

Ehmann, Heike M A; Mohan, Tamilselvan; Koshanskaya, Maria; Scheicher, Sylvia; Breitwieser, Doris; Ribitsch, Volker; Stana-Kleinschek, Karin; Spirk, Stefan

2014-11-01

268

3D fractal-based characterisation for engineered surface topography  

Microsoft Academic Search

We investigate the concept of surface roughness by assuming that z(x) verifies a Lipschitz condition in terms of variance var(z(x+?)?z(x))????2H with 0surfaces are only locally self-affine at scale where the prev relation is verified. The Lipshitz Hölder exponent H, which is directly connected to the surface fractal dimension D, is determined from the log-log plot of

J. Lopez; G. Hansali; H. Zahouani; J. C. Le Bosse; T. Mathia

1995-01-01

269

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

270

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

NASA Astrophysics Data System (ADS)

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

Morjan, Martin; Züchner, Harald; Cammann, Karl

2009-06-01

271

Flow condensation on copper-based nanotextured superhydrophobic surfaces.  

PubMed

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

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

2013-01-15

272

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

273

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

274

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

275

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

276

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

277

Cauchy problem as a two-surface based ‘geometrodynamics’  

NASA Astrophysics Data System (ADS)

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 {{? }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 {{? }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. Dedicated to Zoltán Cseke on the occasion of his 70th birthday.

Rácz, István

2015-01-01

278

Ground-based measurement of surface temperature and thermal emissivity  

NASA Technical Reports Server (NTRS)

Motorized cable systems for transporting infrared thermometers have been used successfully during several international field campaigns. Systems may be configured with as many as four thermal sensors up to 9 m above the surface, and traverse a 30 m transect. Ground and canopy temperatures are important for solving the surface energy balance. The spatial variability of surface temperature is often great, so that averaged point measurements result in highly inaccurate areal estimates. The cable systems are ideal for quantifying both temporal and spatial variabilities. Thermal emissivity is also necessary for deriving the absolute physical temperature, and measurements may be made with a portable measuring box.

Owe, M.; Van De Griend, A. A.

1994-01-01

279

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

280

Correspondences search for surface-based intra-operative registration.  

PubMed

Intra-operative registration is one of the main challenges related to computer-assisted interventions. One common approach involves matching intra-operatively acquired surfaces (e.g. from a laser range scanner) to pre-operatively acquired planning data. In this paper, we propose a new method for correspondences search between surfaces, which can be used for the computation of an initial alignment. It generates graph representations and establishes correspondences by maximizing a global similarity measure. The method does not rely on landmarks or prominent surface characteristics and is independent on the initial pose of the surfaces relative to each other. According to an evaluation on a set of liver meshes, the method is able to correctly match small submeshes even in this presence of noise. PMID:20879372

dos Santos, Thiago R; Seitel, Alexander; Meinzer, Hans-Peter; Maier-Hein, Lena

2010-01-01

281

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.

282

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

283

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

284

Forced eruption without orthodontic brackets using fiber reinforced composite prostheses: a case report.  

PubMed

Maintenance of periodontal health is one of the most important factors governing success of the restoration and longevity of teeth. For proper maintenance of periodontal health, the biologic width functions as a protective barrier against the entrance of microorganisms in to the internal medium of the periodontal ligament and osseous connective tissue. This clinical case describes a technique to reestablish the biologic width surrounding a fractured central incisor by forced eruption without orthodontic brackets, using fibre reinforced composite prostheses. Main advantages of using fibre reinforced composite prostheses are aesthetic maintenance during the treatment period, no need for occlusal adjustments, simplicity, low cost, and stability. PMID:23101175

Mete, J J; Dange, S P; Khalikar, A N; Vaidya, S P

2012-09-01

285

From Dirac Notation to Probability Bracket Notation: Time Evolution and Path Integral under Wick Rotations  

E-print Network

In this article, we continue to investigate the application of Probability Bracket Notation (PBN). We show that, under Special Wick Rotation (caused by imaginary-time rotation), the Schrodinger equation of a conservative system and its path integral in Dirac rotation are simultaneously shifted to the master equation and its Euclidean path integral of an induced micro diffusion in PBN. Moreover, by extending to General Wick Rotation and using the anti-Hermitian wave-number operator, we execute the path integral in Dirac notation side-by-side with the Euclidean path integral in PBN, and derive the Euclidean Lagrangian of induced diffusions and Smoluchowski equation.

Xing M. Wang

2009-01-30

286

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

287

Probability Bracket Notation: the Unified Expressions of Conditional Expectation and Conditional Probability in Quantum Modeling  

E-print Network

After a brief introduction to Probability Bracket Notation (PBN), indicator operator and conditional density operator (CDO), we investigate probability spaces associated with various quantum systems: system with one observable (discrete or continuous), system with two commutative observables (independent or dependent) and a system of indistinguishable non-interacting many-particles. In each case, we derive unified expressions of conditional expectation (CE), conditional probability (CP), and absolute probability (AP): they have the same format for discrete or continuous spectrum; they are defined in both Hilbert space (using Dirac notation) and probability space (using PBN); and they may be useful to deal with CE of non-commutative observables.

Xing M. Wang

2009-11-07

288

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

PubMed Central

Background ?-amyloid (A?) plaques in brain's grey matter (GM) are one of the pathological hallmarks of Alzheimer's disease (AD), and can be imaged in vivo using Positron Emission Tomography (PET) with 11C or 18F radiotracers. Estimating A? burden in cortical GM has been shown to improve diagnosis and monitoring of AD. However, lacking structural information in PET images requires such assessments to be performed with anatomical MRI scans, which may not be available at different clinical settings or being contraindicated for particular reasons. This study aimed to develop an MR-less A? imaging quantification method that requires only PET images for reliable A? burden estimations. Materials and Methods The proposed method has been developed using a multi-atlas based approach on 11C-PiB scans from 143 subjects (75 PiB+ and 68 PiB- subjects) in AIBL study. A subset of 20 subjects (PET and MRI) were used as atlases: 1) MRI images were co-registered with tissue segmentation; 2) 3D surface at the GM-WM interfacing was extracted and registered to a canonical space; 3) Mean PiB retention within GM was estimated and mapped to the surface. For other participants, each atlas PET image (and surface) was registered to the subject's PET image for PiB estimation within GM. The results are combined by subject-specific atlas selection and Bayesian fusion to generate estimated surface values. Results All PiB+ subjects (N?=?75) were highly correlated between the MR-dependent and the PET-only methods with Intraclass Correlation (ICC) of 0.94, and an average relative difference error of 13% (or 0.23 SUVR) per surface vertex. All PiB- subjects (N?=?68) revealed visually akin patterns with a relative difference error of 16% (or 0.19 SUVR) per surface vertex. Conclusion The demonstrated accuracy suggests that the proposed method could be an effective clinical inspection tool for A? imaging scans when MRI images are unavailable. PMID:24427295

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

2014-01-01

289

Monocular Template-Based 3D Surface Reconstruction: Convex Inextensible and Nonconvex Isometric Methods  

E-print Network

Monocular Template-Based 3D Surface Reconstruction: Convex Inextensible and Nonconvex Isometric.Bartoli@gmail.com Abstract We study the 3D reconstruction of an isometric surface from point correspondences between a tem isometric constraint and the same continuous surface model. It is formulated with Nonlinear Least

Bartoli, Adrien

290

The k-model - green's function based analysis of surface acoustic wave devices  

Microsoft Academic Search

We have derived a model for the analysis of surface acoustic wave devices based on relating the surface potential adherent to surface acoustic waves propagating on a piezoelectric substrate and applied transducer potentials. Device structures are analyzed on the basis of the Green's function, including end effects, electrical loading, mass loading effects, electrode resis- tance, dispersion, and propagation loss, leading

J. H. Kuypers; D. A. Eisele; L. M. Reindl

2005-01-01

291

Efficiency Improvements for RBF Based Surface Measurement from 3D Point Cloud  

Microsoft Academic Search

RBF based surface recovery provides good implicit representation of 3D object's shapes, but it has the disadvantage of time consuming. To apply automatic surface measurement from scanned 3D points in industry, this paper presents several techniques for efficiency improvements of RBF method. Partial surface recovery, octree division and combination, inverse power method and improved Cholesky factorization can either avoid unnecessary

Yihua Ding; Jianhui Zhao; Yuanyuan Zhang; Chengjiang Long; Zhiyong Yuan

2008-01-01

292

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

293

An ex vivo assessment of resin-modified glass ionomer bonding systems in relation to ceramic bracket debond.  

PubMed

This ex vivo study assessed three new resin-modified glass ionomer cements (Fuji ORTHO LC, Vitremer, and Dyract-Cem) in relation to ceramic bracket removal. It was hypothesized that the use of these cements would facilitate bracket removal and eliminate debond complications Eighty extracted premolar teeth were divided into four groups of 20 teeth and bonded with Intrigue brackets using each of the resin-modified cements (groups 1, 2, and 3), the control group 4 was bonded with Concise chemically-cured adhesive. The teeth were debonded by applying a shear load using an Instron universal testing machine. The mean force to debond was calculated for each group and each tooth was examined under the stereomicroscope to record the site of bond failure and the Adhesive Remnant Index (ARI). The results showed that the resin-modified cements were very effective at eliminating ceramic bracket debond problems. Bracket fracture was eliminated compared with a 40 per cent fracture rate with the control and the ARI scores were all reduced. The elimination of debond problems appears to be related to the significantly reduced (P < 0.001 using ANOVA and Tukey tests) mean and maximal debond forces compared with the control. PMID:11099572

Larmour, C J; McCabe, J F; Gordon, P H

2000-12-01

294

Laser-based nanoengineering of surface topographies for biomedical applications  

NASA Astrophysics Data System (ADS)

In this study femtosecond laser systems were used for nanoengineering of special surface topographies in silicon and titanium. Besides the control of feature sizes, we demonstrated that laser structuring caused changes in material wettability due to a reduced surface contact area. These laser-engineered topographies were tested for their capability to control cellular behavior of human fibroblasts, SH-SY5Y neuroblastoma cells, and MG-63 osteoblasts. We found that fibroblasts reduced cell growth on the structures, while the other cell types proliferated at the same rate. These findings make laser-surface structuring very attractive for biomedical applications. Finally, to explain the results the correlation between topography and the biophysics of cellular adhesion, which is the key step of selective cell control, is discussed.

Schlie, Sabrina; Fadeeva, Elena; Koroleva, Anastasia; Ovsianikov, Aleksandr; Koch, Jürgen; Ngezahayo, Anaclet; Chichkov, Boris. N.

2011-04-01

295

Cyclodextrin-based surface acoustic wave chemical microsensors  

SciTech Connect

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

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

1996-07-01

296

Surface characteristics of chitin-based shape memory polyurethane elastomers.  

PubMed

Shape memory polyurethanes (SMPUs) were prepared from polycaprolactone diol 4000 (PCL 4000), 1,4-butanediol (BDO), chitin, dimethylol propionic acid (DMPA), triethylamine (TEA) and 4,4'-diphenylmethane diisocyanate (MDI), and the structures of the synthesized materials were verified by infrared spectroscopy. The effects of chitin and DMPA contents in the polyurethane formulation on surface properties were investigated. DMPA provides function of making hydrophilic polyurethanes. The crystalline structure of chitin enhanced the hydrophobicity of the synthesized materials. Contact angle, water absorption, surface free energy, work of water adhesion and swelling behavior of the synthesized polyurethanes were affected by varying the DMPA and chitin contents. The interactions of the PU films with solvents on the surface were clearly related to the contents of DMPA and chitin in the final polyurethane formulation. PMID:19427176

Zia, Khalid Mahmood; Zuber, Mohammad; Barikani, Mehdi; Bhatti, Ijaz Ahmad; Khan, Mohammad Bilal

2009-09-01

297

Characterization and Applications of Affinity Based Surface Modification of Polypyrrole  

NASA Astrophysics Data System (ADS)

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

Nickels, Jonathan D.

298

Surface-Charge-Based Micro-Models--A Solid Foundation for Learning about Direct Current Circuits  

ERIC Educational Resources Information Center

This study explores how the use of a surface-charge-based instructional approach affects introductory university level students' understanding of direct current (dc) circuits. The introduced teaching intervention includes electrostatics, surface-charge-based micro-models that explain the existence of an electric field inside the current-carrying…

Hirvonen, P. E.

2007-01-01

299

2013 ISES Solar World Congress Review of satellite-based surface solar irradiation databases for  

E-print Network

2013 ISES Solar World Congress Review of satellite-based surface solar irradiation databases explores the possibilities provided by satellite-based surface solar irradiation databases of solar dataset or time-series is addressed with the example of the French national meteorological network

Recanati, Catherine

300

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 using jour Canadian linseed oil- based sealants on concrete specimens madejrom G30120 and G45120 Keywords: Unseed Oil, Concrete Surface Treatment, Salt Spray Resistance, Carbonation, Bond Strength, Ultra

301

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 ...

302

Mastering Interactive Surface Rendering for JavaBased Diagnostic Applications  

E-print Network

of iso­surfaces in medical data sets is an important vi­ sualization technique used by radiologists for the diagnosis of vol­ umetric density data sets. The demands put by radiologists on such a display technique. CR Categories: I.3.3 [Computer Graphics]: Picture / Image generation---display algorithms; J.3 [Life

303

Shape-based Diffeomorphic Registration on Hippocampal Surfaces Using Beltrami  

E-print Network

(Alzheimer's dis- ease) subjects show our proposed algorithm is effective in registering HP surfaces, for shape analysis in Alzheimer's disease, schizophrenia and epilepsy. 1 Introduction The hippocampus to pathologies such as Alzheimer disease (AD), schizophrenia and epilepsy[11]. When comparing data on two

304

Corrosion protection of aluminum by silane-based surface treatment  

Microsoft Academic Search

The possibility of using silane coupling agents as replacements for chromate treatments was investigated for aluminum substrates. In order to understand the influence of deposition parameters on silane film formation, pure Al substrates were used to study the interaction between silane coupling agents and aluminum surfaces. The silane films formed on pure A1 substrates from aqueous solutions were characterized by

Jun Song

2004-01-01

305

Micro mixer based on surface acoustic wave driving  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

306

Standing surface acoustic wave (SSAW) based multichannel cell sorting.  

PubMed

We introduce a novel microfluidic device for cell sorting in continuous flow using tunable standing surface acoustic waves. This method allows individual cells to be precisely directed into five different outlet channels in a single step. It is versatile, simple, label-free, non-invasive, and highly controllable. PMID:22992833

Ding, Xiaoyun; Lin, Sz-Chin Steven; Lapsley, Michael Ian; Li, Sixing; Guo, Xiang; Chan, Chung Yu; Chiang, I-Kao; Wang, Lin; McCoy, J Philip; Huang, Tony Jun

2012-11-01

307

Asteroid surface mineralogy: Evidence from earth-based telescope observations  

NASA Technical Reports Server (NTRS)

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

Mccord, T. B.

1978-01-01

308

Adaptive Surface Reconstruction Based on Implicit PHT-Splines  

E-print Network

:chenfl@ustc.edu.cn Permission to make digital or hard copies of all or part of this work for personal or classroom use in many industries, such as jewelry and automobile industries, where free-form surfaces are usually used of point samples, which constitute the discrete building blocks of 3D object geometry. 1.1 Related work

Deng, Jiansong

309

Prototype Modeling from Sketched Silhouettes based on Convolution Surfaces  

Microsoft Academic Search

This paper presents a hybrid method for creating three-dimensional shapes by sketching silhouette curves. Given a silhouette curve, we approximate its medial axis as a set of line segments, and convolve a linearly weighted kernel along each segment. By summing the fields of all segments, an analytical convolution surface is obtained. The resulting generic shape has circular cross-section, but can

Chiew-lan Tai; Hongxin Zhang; Jacky Chun-kin Fong

2004-01-01

310

Incomplete Points Cloud Data Surface Reconstruction Based on Neural Network  

Microsoft Academic Search

Neural network arithmetic was employed in incomplete points cloud data surface reconstruction, Radial basis function neural network and simulated annealing arithmetic was combined. The new arithmetic can approach any nonlinear function by arbitrary precision, and also keep the network from getting into local minimum. Global optimization feature of simulated annealing was employed to adjust the network weights. MATLAB program was

Xue-mei Wu; Gui-xian Li; Wei-min Zhao

2008-01-01

311

Compact RGBD Surface Models Based on Sparse Coding Michael Ruhnke  

E-print Network

with a binary weighting scheme that ignores undefined surface cells. Through exper- imental evaluation on real for the corresponding application. With the availability of cheap RGBD sensors like the recently introduced Microsoft of object detection (Bo, Ren, and Fox 2012) because a search or comparison in the compact sparse code space

Anderson, Richard

312

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.

313

Bracket Gamma, Molecular Hydrogen, and Singly-Ionized Iron in GGD 37 (Cep A West)  

NASA Astrophysics Data System (ADS)

We present near-infrared images of the Herbig-Haro objects in GGD 37 in the 2.166 mu m hydrogen recombination line Bracket gamma (R = 70), molecular hydrogen, v = 1 - 0 S(1), 2.122 mu m line, (R = 70), and in the forbidden ionized iron 1.644 mu m line, (R = 800). The Bracket gamma emission appears as a knot near the location of the HW object. The molecular hydrogen emission forms arcs exterior to the iron emission; the morphology is similar to that of the molecular hydrogen / singly-ionized sulfur image of Hartigan, Carpenter, Dougados and Skrutskie (A.J., 111 (3), 1278, 1996). The peak H_2 and [Fe II] line emissions for several of the H-H objects are clearly separated relative to one another, suggestive of multiple shocks. We compare the relative locations of the peak emisssion to predictions from competing shock models. All observations were carried out at the Wyoming Infrared Observatory 2.3 m telescope with the University of Rochester 3rd Generation Infrared Camera. The iron imaging was accomplished in conjunction with the National Air and Space Museum / Naval Research Laboratory Fabry-Perot Interferometer.

Raines, S. N.; Watson, D. M.; Forrest, W. J.; Pipher, J. L.; Delamarter, G.; Woodward, C. E.; Hodge, T.; Greenhouse, M. A.; Smith, H. A.; Satyapal, S.; Fischer, J.; Thompson, K. L.; Muzerolle, J.

1996-12-01

314

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

315

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

316

Broadband omnidirectional antireflection coating based on subwavelength surface Mie resonators  

PubMed Central

Reflection is a natural phenomenon that occurs when light passes the interface between materials with different refractive index. In many applications, such as solar cells or photodetectors, reflection is an unwanted loss process. Many ways to reduce reflection from a substrate have been investigated so far, including dielectric interference coatings, surface texturing, adiabatic index matching and scattering from plasmonic nanoparticles. Here we present an entirely new concept that suppresses the reflection of light from a silicon surface over a broad spectral range. A two-dimensional periodic array of subwavelength silicon nanocylinders designed to possess strongly substrate-coupled Mie resonances yields almost zero total reflectance over the entire spectral range from the ultraviolet to the near-infrared. This new antireflection concept relies on the strong forward scattering that occurs when a scattering structure is placed in close proximity to a high-index substrate with a high optical density of states. PMID:22353722

Spinelli, P.; Verschuuren, M.A.; Polman, A.

2012-01-01

317

Bionanohybrid based on bioplastic and surface-functionalized carbon nanotubes.  

PubMed

A bionanohybrid consisting of biodegradable/biocompatible poly(butylene succinate) (PBS) and surface-oxidized carbon nanotubes (o-CNTs) was prepared via melt-mixing method. The inherent properties of PBS were concurrently improved by the incorporation of a small amount of o-CNTs. For example, at room temperature, elongation at break increased from approximately 21.2% for pure PBS to approximately 55.1% for the nanohybrid and an increase of about approximately 150% in the value of toughness with moderate improvement in tensile modulus and strength. The dynamic mechanical properties of PBS also increased significantly after nanocomposite formation with o-CNTs. Electron microscopy and Raman spectroscopy were used to investigate the mechanical properties and improvement mechanism of surface-functionalized o-CNTs containing PBS nanohybrid. PMID:21121286

Singh, Ravina; Ray, Suprakas Sinha

2010-12-01

318

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

319

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

320

Broadband omnidirectional antireflection coating based on subwavelength surface Mie resonators  

NASA Astrophysics Data System (ADS)

Reflection is a natural phenomenon that occurs when light passes the interface between materials with different refractive index. In many applications, such as solar cells or photodetectors, reflection is an unwanted loss process. Many ways to reduce reflection from a substrate have been investigated so far, including dielectric interference coatings, surface texturing, adiabatic index matching and scattering from plasmonic nanoparticles. Here we present an entirely new concept that suppresses the reflection of light from a silicon surface over a broad spectral range. A two-dimensional periodic array of subwavelength silicon nanocylinders designed to possess strongly substrate-coupled Mie resonances yields almost zero total reflectance over the entire spectral range from the ultraviolet to the near-infrared. This new antireflection concept relies on the strong forward scattering that occurs when a scattering structure is placed in close proximity to a high-index substrate with a high optical density of states.

Spinelli, P.; Verschuuren, M. A.; Polman, A.

2012-02-01

321

Surface Plasmon Resonance Based Sensitive Immunosensor for Benzaldehyde Detection  

NASA Astrophysics Data System (ADS)

Fragrant compounds used to add flavor to beverages remain in the manufacturing line after the beverage manufacturing process. Line cleanliness before the next manufacturing cycle is difficult to estimate by sensory analysis, making excessive washing necessary. A new measurement system to determine line cleanliness is desired. In this study, we attempted to detect benzaldehyde (Bz) using an anti-Bz monoclonal antibody (Bz-Ab) and a surface plasmon resonance (SPR) sensor. We fabricated two types of sensor chips using self-assembled monolayers (SAMs) and investigated which sensor surface exhibited higher sensitivity. In addition, anti-Bz antibody conjugated with horseradish peroxidase (HRP-Bz-Ab) was used to enhance the SPR signal. A detection limit of ca. 9ng/mL (ppb) was achieved using an immobilized 4-carboxybenzaldehyde sensor surface using SAMs containing ethylene glycol. When the HRP-Bz-Ab concentration was reduced to 30ng/mL, a detection limit of ca. 4ng/mL (ppb) was achieved for Bz.

Onodera, Takeshi; Shimizu, Takuzo; Miura, Norio; Matsumoto, Kiyoshi; Toko, Kiyoshi

322

Inconsistencies in surface anatomy: The need for an evidence-based reappraisal.  

PubMed

Accurate surface anatomy is a key component of safe clinical practice. But how consistent are modern clinical and surface anatomy texts in their reporting of common surface anatomy landmarks? Thirteen popular texts in common use were analyzed in detail: one clinical and anatomical reference text; seven clinical anatomy texts; two surface anatomy texts; and three clinical examination texts. Content relating to surface anatomy was reviewed, summarized, and assessed for consistency. Four main findings emerged: (i) there are numerous inconsistencies in clinically important surface markings (e.g., the femoral artery in the groin, superficial and deep inguinal rings, and accessory nerve in the posterior triangle), including inconsistencies within some texts; (ii) there is a consensus on many surface markings, e.g., the spleen and termination of the spinal cord; (iii) few texts address variation in surface anatomy related to age, sex, body mass, posture, respiration, and ethnicity; and (iv) the three standard clinical examination texts included in this review contain comparatively little surface anatomy. Seven surface anatomy landmarks were redefined within an evidence-based framework: termination of the spinal cord, supracristal plane, base of the appendix, renal length, the deep inguinal ring, the femoral artery in the groin, and the accessory nerve in the posterior triangle of the neck. An evidence-based framework is essential if surface anatomy is to be accurate and clinically relevant. PMID:20830790

Hale, Samuel J M; Mirjalili, S Ali; Stringer, Mark D

2010-11-01

323

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

324

CAD system for footwear design based on whole real 3D data of last surface  

NASA Astrophysics Data System (ADS)

Two major parts of application of CAD in footwear design are studied: the development of last surface; computer-aided design of planar shoe-template. A new quasi-experiential development algorithm of last surface based on triangulation approximation is presented. This development algorithm consumes less time and does not need any interactive operation for precisely development compared with other development algorithm of last surface. Based on this algorithm, a software, SHOEMAKERTM, which contains computer aided automatic measurement, automatic development of last surface and computer aide design of shoe-template has been developed.

Song, Wanzhong; Su, Xianyu

2000-10-01

325

A surface systems architecture for an evolutionary lunar base  

NASA Technical Reports Server (NTRS)

The NASA Office of Exploration has completed a Systems Engineering and Integration effort to define a point design for an evolving lunar base that supports substantial science, exploration, and resource production objectives. This study addressed systems level design; element requirements and conceptual designs; assessments of precursor and technology needs, and operations concepts. The central base is assumed to be located equatorially on the lunar nearside north of the crater Moltke in Mare Tranquillitatis. The study considers an aggressive case with three main phases. The initial Man-Tended Phase establishes basic enabling facilities that include a modular habitat that periodically houses a crew of four. During the Experimental Phase the base becomes permanently manned with the construction of a larger habitat that provides augmented workshop and laboratory volumes and housing for crew. The Operational Phase expands base capabilities to a substantially mature level while reducing reliance on earth.

Roberts, Barney B.; Pieniazek, Lester A.

1990-01-01

326

Research on optical surface quality online monitoring based on support vector machine  

NASA Astrophysics Data System (ADS)

The interference of grinding wheel and optic surface during grinding process causes numerous acoustic emission (AE) phenomena. AE signals are competent for monitoring the quality of the ground surface. A quality prediction model of grinding optics is established based on support vector machine (SVM). Some time domain characteristics of AE signals are chosen as the input vectors. And surface roughness (Ra) and surface shape accuracy (P-V) are the output vectors, respectively. The experiment results show that the model can accurately predict the surface quality of the optics during grinding.

Bi, Guo; Sun, Zhiji; Zhang, Dongxu

2014-08-01

327

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

328

Development of surface plasmon based x-ray detector  

NASA Astrophysics Data System (ADS)

We propose a novel ultra-fast x-ray detector by use of the evanescent field assisted by surface plasmon resonance (SPR). Under the SPR condition driven by the short laser pulse, the plasmons in the metal surface are excited followed by emitting free electrons in vacuum, which are accerelated by the gradient of the strength of the evanescent electric field. Under the condition that an additional x-ray pulse is temporally synchronized with the driving pulse of SPR, the kinetic energy of the emitted electrons originated from the evanescent field may be shifted due to the effect of the photoionization with the incident x-ray. This scheme has potential to determine the duration of the x-ray pulse by monitoring the energy shift as a function of the timing of the driving pulse of SPR. The temporal resolution is comparable to the decay time of the plasmon excitation, which is around 50 fs. In the presentation, we report the preliminary experiment and show the prospect of this scheme as the ultra-fast x-ray detector.

Kunieda, Yuichi; Kawachi, Tetsuya; Hasegawa, Noboru; Nagashima, Keisuke

2008-11-01

329

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

330

Surface-based supramolecular chemistry using hydrogen bonds.  

PubMed

Conspectus The arrangement of molecular species into extended structures remains the focus of much current chemical science. The organization of molecules on surfaces using intermolecular interactions has been studied to a lesser degree than solution or solid-state systems, and unanticipated observations still lie in store. Intermolecular hydrogen bonds are an attractive tool that can be used to facilitate the self-assembly of an extended structure through the careful design of target building blocks. Our studies have focused on the use of 3,4,9,10-perylene tetracarboxylic acid diimides (PTCDIs), and related functionalized analogues, to prepare extended arrays on surfaces. These molecules are ideal for such studies because they are specifically designed to interact with appropriate diaminopyridine-functionalized molecules, and related species, through complementary hydrogen bonds. Additionally, PTCDI species can be functionalized in the bay region of the molecule, facilitating modification of the self-assembled structures that can be prepared. Through a combination of PTCDI derivatives, sometimes in combination with melamine, porous two-dimensional arrays can be formed that can entrap guest molecules. The factors that govern the self-assembly processes of PTCDI derivatives are discussed, and the ability to construct suitable target arrays and host-specific molecular species, including fullerenes and transition metal clusters, is demonstrated. PMID:25330179

Slater, Anna G; Perdigão, Luis M A; Beton, Peter H; Champness, Neil R

2014-12-16

331

Rough surface scattering results based on bandpass autocorrelation forms  

NASA Technical Reports Server (NTRS)

Surface-height autocorrelation forms such as Gaussian and exponential are often used in studies of near-normal incidence rough-surface scattering. Such models require the existence of a constant, or DC, value in the spectrum. The consequences of autocorrelation forms that correspond to spectral processes that are essentially bandpass in nature are examined. One such process is that of ocean wind waves. In this case, the spectral components do not extend down to zero frequency. The physical optics backscatter theory is reexamined relative to such autocorrelation functions. Experimental results obtained from a wavetank are compared to the autocorrelation model used in the analysis. The analysis indicates that Gaussian correlation length or mean-square slope is not an appropriate parameter for narrowband conditions and that significant slope is a more relevant parameter. Inherent in the deep-phase assumption is some form of slope dependency. The analysis given (and variants thereof) can be used to provide insight into the physical effects of separate spectral components and of spectral directionality.

Miller, Lee S.; Parsons, Chester L.

1990-01-01

332

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

333

Laser surface annealing of Ni-base superalloy for enhancement of material performance in hydrogen environment  

NASA Astrophysics Data System (ADS)

In the present work, laser surface annealing has been applied to an age-hardened Ni base supper alloy Inconel 718 using a 2.5kW CO2 laser to improve its performance in hydrogen environment. Laser surface annealing can produce a locally solutionized zone at the surface of Inconel 718. In the solutionized zone the age precipitates of (gamma) ' and (gamma) '' are dissolved in the matrix, and thereby the hardness of the solutionized zones is reduced to below 250Hv from approximately 450Hv of the aged base metal hardness. The surface softened zones having several hundred micro meters in depth can be obtained without melting the treated zone by controlling the laser parameters, i.e. thee defocus distance and traverse speed. Having much greater ductility than the aged base metal in hydrogen environment, the surface softened zones can effectively prevent hydrogen induced cracking, which tends to occur at the surface of a stress concentrated region. In the present case, the ductility of the surface annealed specimen is almost twice that of the base metal in a tensile test under a 29.3MPa hydrogen atmosphere at room temperature with hydrogen pre- charging. Since a controlled laser irradiation can precisely and locally anneal the surface of a stress concentrated region where hydrogen induced cracking is liable to occur, a sacrifice of strength of the structure caused by the surface softening is negligible.

Hirose, Akio; Liu, Liufa; Kobayashi, Kojiro F.

2000-11-01

334

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

335

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

336

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

337

Surface-enhanced Raman spectroscopy based on ordered nanocap arrays  

NASA Astrophysics Data System (ADS)

We fabricated the Ag cap array for surface-enhanced Raman scattering (SERS) by Ag deposition onto two dimensional polystyrene colloid sphere templates, and 4-mercaptopyridine (4-MPy) was used as the probing molecule. When the colloids with different size were chosen as the substrate for 20 nm Ag deposition, the film on 100 nm colloids gave the significant enhancement. SERS intensity increased with the increase of Ag thickness. When 20 nm Ag film was coated by Ta, the SERS signals decreased with the increase of Ta thickness, indicating the main effect from the top of cap structure. When Co layer was added under the Ag film, the SERS intensity decreased with the increase of Co thickness because the Co layer affects electromagnetic and plasmon resonance.

Wang, Y. X.; Liu, S. S.; Gao, W. T.; Li, W.; Zhang, Y. J.; Yang, J. H.

2012-10-01

338

Surface plasmon resonance based biosensor technique: a review.  

PubMed

Optical Surface plasmon resonance (SPR) biosensors represent the most advanced and developed optical label-free biosensor technology. Optical SPR biosensors are a powerful detection and analysis tool that has vast applications in environmental protection, biotechnology, medical diagnostics, drug screening, food safety and security. This article reviews the recent development of SPR biosensor techniques, including bulk SPR and localized SPR (LSPR) biosensors, for detecting interactions between an analyte of interest in solution and a biomolecular recognition. The concepts of bulk and localized SPs and the working principles of both sensing techniques are introduced. Major sensing advances on biorecognition elements, measurement formats, and sensing platforms are presented. Finally, the discussions on both biosensor techniques as well as comparison of both SPR sensing techniques are made. PMID:22467335

Guo, Xiaowei

2012-07-01

339

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

340

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

341

Version 2 Goddard Satellite-Based Surface Turbulent Fluxes (GSSTF2)  

NASA Technical Reports Server (NTRS)

Information on the turbulent fluxes of momentum, moisture, and heat at the air-sea interface is essential in improving model simulations of climate variations and in climate studies. We have derived a 13.5-year (July 1987-December 2000) dataset of daily surface turbulent fluxes over global oceans from the Special Sensor Mcrowave/Imager (SSM/I) radiance measurements. This dataset, version 2 Goddard Satellite-based Surface Turbulent Fluxes (GSSTF2), has a spatial resolution of 1 degree x 1 degree latitude-longitude and a temporal resolution of 1 day. Turbulent fluxes are derived from the SSM/I surface winds and surface air humidity, as well as the 2-m air and sea surface temperatures (SST) of the NCEP/NCAR reanalysis, using a bulk aerodynamic algorithm based on the surface layer similarity theory.

Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.; Shie, Chung-Lin; Starr, David O'C. (Technical Monitor)

2002-01-01

342

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...

343

Subpixel measurement of image features based on paraboloid surface fit  

Microsoft Academic Search

A digital image processing inspection system is under development at Oak Ridge National Laboratory that will locate image features on printed material and measure distances between them to accuracies of 0.001 in. An algorithm has been developed for this system that can locate unique image features to subpixel accuracies. It is based on a least-squares fit of a paraboloid function

Shaun S. Gleason; Martin A. Hunt; W. Bruce Jatko

1990-01-01

344

Surface chemistry of tin oxide based gas sensors  

Microsoft Academic Search

Four types of gas sensors based on SnOx thin film with and without additives (Pt and Sb) were investigated by means of x-ray photoelectron spectroscopy and scanning Auger microscopy. The sensors were deposited on Si substrates by using reactive dc magnetron sputtering. The temperature dependencies of the electrical resistivity response to CO gas exposure were measured in order to characterize

G. Gaggiotti; A. Galdikas; S. Kaciulis; G. Mattogno; A. Setkus

1994-01-01

345

Surfaces and interfaces in polymer-based electronics  

Microsoft Academic Search

Research on electronics applications such as light-emitting devices for flat-panel displays, transistors, sensors and even solid state lasers based on conducting polymers is presently under way and in some cases has reached the stage of prototype production. The mechanisms for charge injection and conduction in these materials are being studied, as are the physics of luminescence and its quenching. Lately,

M. Fahlman; W. R. Salaneck

2002-01-01

346

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

347

A Wavelet–Fractal-Based Approach for Composite Characterisation of Engineering Surfaces  

Microsoft Academic Search

Many types of engineering surfaces have been seen to have fractal characteristics. A good model of the properties can be produced\\u000a using wavelet-based expansions. For multiscale analysis of surface topography, a difficulty exists in determining quantitatively\\u000a the feature separation index for comprehensively characterising roughness, waviness, and form errors from a primary surface\\u000a structure. In this project, we utilise the fractal

S. Tse; Y. Goa; S. Lu

2002-01-01

348

An Interacting Gauge Field Theoretic Model for Hodge Theory: Basic Canonical Brackets  

NASA Astrophysics Data System (ADS)

We derive the basic canonical brackets amongst the creation and annihilation operators for a two (1 + 1)-dimensional (2D) gauge held theoretic model of an interacting Hodge theory where a U(1) gauge field (A?) is coupled with the fermionic Dirac fields (? and bar psi). In this derivation, we exploit the spin-statistics theorem, normal ordering and the strength of the underlying six infinitesimal continuous symmetries (and the concept of their generators) that are present in the theory. We do not use the definition of the canonical conjugate momenta (corresponding to the basic fields of the theory) anywhere in our whole discussion. Thus, we conjecture that our present approach provides an alternative to the canonical method of quantization for a class of gauge field theories that are physical examples of Hodge theory where the continuous symmetries (and corresponding generators) provide the physical realizations of the de Rham cohomological operators of differential geometry at the algebraic level.

R., Kumar; Gupta, S.; R. P., Malik

2014-06-01

349

Effect of a self-etch primer\\/adhesive on the shear bond strength of orthodontic brackets  

Microsoft Academic Search

Conventional adhesive systems use 3 different agents (an enamel conditioner, a primer solution, and an adhesive resin) during the bonding of orthodontic brackets to enamel. A unique characteristic of some new bonding systems in operative dentistry is that they combine the conditioning and priming agents into a single product. Combining conditioning and priming saves time and should be more cost-effective

Samir E. Bishara; Leigh VonWald; John F. Laffoon; John J. Warren

2001-01-01

350

Bio-based hyperbranched polyurethanes for surface coating applications  

Microsoft Academic Search

High performance vegetable oil based hyperbranched polymers are not only interesting but also very useful with respect to current scenario of advanced coating materials. So in the present study hyperbranched polyurethanes have been synthesized from the monoglyceride of Mesua ferrea L. seed oil, poly(?-caprolactone)diol, 2,4-toluene diisocyanate and glycerol without using any catalyst by a two-step one pot A2+B3 approach. The

Harekrishna Deka; Niranjan Karak

2009-01-01

351

Surface Plasmon Sensor Based on the Enhanced Light Transmission through Arrays of Nanoholes in Gold Films  

E-print Network

Surface Plasmon Sensor Based on the Enhanced Light Transmission through Arrays of Nanoholes in Gold resonance (SPR) devices. The array of nanoholes is well suited for dense integration in a sensor chip Kretschmann (reflection) arrangement for SPR sensing. Surface plasmon resonance (SPR) sensors are widely used

Brolo, Alexandre G.

352

Graphene-based long-wave infrared TM surface plasmon modulator  

Microsoft Academic Search

We describe theoretically a new long-wave infrared optical modulator based on the characteristics of TM surface plasmons in graphene. Calculations made using a finite-? random phase approxima- tion model, of relevant surface plasmon propagation parameters, are presented. We show that the plasmon losses vary as a function of carrier density; for large carrier densities, interband absorption of the plasmon energy

David R. Andersen

2010-01-01

353

Differentiation of red wines using an electronic nose based on surface acoustic wave devices  

Microsoft Academic Search

An electronic nose, utilizing the principle of surface acoustic waves (SAW), was used to differentiate among different wines of the same variety of grapes which come from the same cellar. The electronic nose is based on eight surface acoustic wave sensors, one is a reference sensor and the others are coated by different polymers by spray coating technique. Data analysis

M. García; M. J. Fernández; J. L. Fontecha; J. Lozano; J. P. Santos; M. Aleixandre; I. Sayago; J. Gutiérrez; M. C. Horrillo

2006-01-01

354

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

355

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

356

Stability Conditions on Kummer Surfaces (based on arXiv:1201.5830)  

E-print Network

Stability Conditions on Kummer Surfaces (based on arXiv:1201.5830) Magnus Engenhorst Mathematisches Institut, Universität Freiburg 05.09.2012 Magnus Engenhorst (Universität Freiburg) Stability Conditions on Kummer Surfaces 05.09.2012 1 / 17 #12;Introduction Why stability conditions? 1 associates a complex

Bovier, Anton

357

Three-dimensional reconstruction of a surface based on scanning electron microscopy images  

NASA Astrophysics Data System (ADS)

Modern methods of three-dimensional reconstruction of sample surfaces based on scanning electron microscopy images allow one to quantitatively estimate morphological surface characteristics (specifically, parameters of irregularities, volumes of convexities and concavities, etc.). The accuracy of the method is analyzed by an example of commercial and specially prepared test samples. Examples of application to various objects are given.

Mikhutkin, A. A.; Vasiliev, A. L.

2014-11-01

358

Improving satellite-based rainfall estimates over land using spaceborne surface soil moisture retrievals  

Technology Transfer Automated Retrieval System (TEKTRAN)

Over land, remotely-sensed surface soil moisture and precipitation accumulation retrievals contain complementary information that can be exploited for the mutual benefit of both products. Here a Kalman filtering based tool is developed that utilizes a time series of spaceborne surface soil moisture ...

359

Structural and Functional Analyses of Human Cerebral Cortex Using a Surface-Based Atlas  

E-print Network

Structural and Functional Analyses of Human Cerebral Cortex Using a Surface-Based Atlas D. C. Van- spheres generated from a digital atlas (the Visible Man). The total surface area of the reconstructed areas VP and V4v) involved in both form and color processing. Foci associated with motion processing

Van Essen, David

360

Proxy-based reconstructions of hemispheric and global surface temperature variations  

E-print Network

Proxy-based reconstructions of hemispheric and global surface temperature variations over the past Press, Washington, DC).], we reconstruct surface temperature at hemi- spheric and global scale for much centuries. Many previous proxy data studies have emphasized hemispheric or global mean temperature (3

Lachniet, Matthew S.

361

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

362

Silicon carbide surface structure investigated by synchrotron radiation-based x-ray diffraction  

E-print Network

Silicon carbide surface structure investigated by synchrotron radiation-based x-ray diffraction H silicon or germanium surfaces. © 2003 American Vacuum Society. DOI: 10.1116/1.1588650 Silicon carbide Si, with alternating silicon and carbon atomic planes in the 100 direction, so that one can expect some similarity

Chiang, Shirley

363

Protein Patterning Based on Electrochemical Activation of Bioinactive Surfaces with Hydroquinone-Caged Biotin  

E-print Network

Protein Patterning Based on Electrochemical Activation of Bioinactive Surfaces with Hydroquinone@pusan.ac.kr (H.Y.) An efficient attachment and patterning method of proteins on surfaces is crucial to the construction of protein chips1 and bioelectronic devices.2 In the attachment step, the site

Kwak, Juhyoun

364

Fast Surface Reconstruction and Segmentation with Ground-Based and Airborne LIDAR Range Data1  

E-print Network

Fast Surface Reconstruction and Segmentation with Ground-Based and Airborne LIDAR Range Data1 and fly through, urban planning, disaster management, object recognition, training, and simulations. In this paper, we present general methods for surface reconstruction and segmentation of 3D colored point clouds

Zakhor, Avideh

365

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

366

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

367

Fully automated Liquid Extraction-Based Surface Sampling and Ionization Using a Chip-Based Robotic Nanoelectrospray Platform  

SciTech Connect

A fully automated liquid extraction-based surface sampling device utilizing an Advion NanoMate chip-based infusion nanoelectrospray ionization system is reported. Analyses were enabled for discrete spot sampling by using the Advanced User Interface of the current commercial control software. This software interface provided the parameter control necessary for the NanoMate robotic pipettor to both form and withdraw a liquid microjunction for sampling from a surface. The system was tested with three types of analytically important sample surface types, viz., spotted sample arrays on a MALDI plate, dried blood spots on paper, and whole-body thin tissue sections from drug dosed mice. The qualitative and quantitative data were consistent with previous studies employing other liquid extraction-based surface sampling techniques. The successful analyses performed here utilized the hardware and software elements already present in the NanoMate system developed to handle and analyze liquid samples. Implementation of an appropriate sample (surface) holder, a solvent reservoir, faster movement of the robotic arm, finer control over solvent flow rate when dispensing and retrieving the solution at the surface, and the ability to select any location on a surface to sample from would improve the analytical performance and utility of the platform.

Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

2010-01-01

368

Surface-Enhanced Raman Scattering Based Ligase Detection Reaction  

PubMed Central

Genomics provides a comprehensive view of the complete genetic makeup of an organism. Individual sequence variations, as manifested by single nucleotide polymorphisms (SNPs), can provide insight into the basis for a large number of phenotypes and diseases including cancer. The ability rapidly screen for SNPs will have a profound impact on a number of applications, most notably personalized medicine. Here we demonstrate a new approach to SNP detection through the application of surface-enhanced Raman scattering (SERS) to the ligase detection reaction (LDR). The reaction uses two LDR primers, one of which contains a Raman enhancer and the other a reporter dye. In LDR, one of the primers is designed to interrogate the SNP. When the SNP being interrogated matches the discriminating primer sequence, the primers are ligated and the enhancer and dye are brought into close proximity enabling the dye’s Raman signature to be detected. By detecting the Raman signature of the dye rather than its fluorescence emission, our technique avoids the problem of spectral overlap which limits number of reactions which can be carried out in parallel by existing systems. We demonstrate the LDR-SERS reaction for the detection of point mutations in the human K-ras oncogene. The reaction is implemented in an electrokinetically active microfluidic device that enables physical concentration of the reaction products for enhanced detection sensitivity and quantization. We report a limit of detection of 20 pM of target DNA with the anticipated specificity engendered by the LDR platform. PMID:19199618

Huh, Yun Suk; Lowe, Adam J.; Strickland, Aaron D.; Batt, Carl A.; Erickson, David

2009-01-01

369

Spline-based models for predictiveness curves and surfaces  

PubMed Central

A biomarker is defined to be a biological characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. The use of biomarkers in cancer has been advocated for a variety of purposes, which include use as surrogate endpoints, early detection of disease, proxies for environmental exposure and risk prediction. We deal with the latter issue in this paper. Several authors have proposed use of the predictiveness curve for assessing the capacity of a biomarker for risk prediction. For most situations, it is reasonable to assume monotonicity of the biomarker effects on disease risk. In this article, we propose the use of flexible modelling of the predictiveness curve and its bivariate analogue, the predictiveness surface, through the use of spline algorithms that incorporate the appropriate monotonicity constraints. Estimation proceeds through use of a two-step algorithm that represents the “smooth, then monotonize” approach. Subsampling procedures are used for inference. The methods are illustrated to data from a melanoma study. PMID:22003414

Ghosh, Debashis; Sabel, Michael

2010-01-01

370

Cell-based Metabolomics for Monitoring Ecological Impacts of Environmental Surface Waters  

EPA Science Inventory

Numerous surface waters are adversely impacted by contaminants released from sources such as WWfPs, CAFOs, mining activities, and agricultural operations. Ideally, an assessment strategy for these applications would include both chemical identification and effects-based monitorin...

371

Ultraviolet-sensitive AlGaN-based surface acoustic wave devices  

Microsoft Academic Search

Two types of novel ultraviolet-sensitive III-nitride based surface acoustic wave devices are presented. We demonstrate the AlxGal-xN-based surface acoustic wave delay-line oscillator, which is applied as an ultraviolet sensor capable of solar-blind operation with remote wireless pickup of the output signal. Also, we report on the SAW-induced high-frequency resistance modulation effect, which is dramatically increased under ultraviolet illumination.

D. Ciplys; M. S. Shur; N. Pala; A. Sereika; R. Rimeika; R. Gaska; Q. Fareed

2004-01-01

372

Does the bracket–ligature combination affect the amount of orthodontic space closure over three months? A randomized controlled trial  

PubMed Central

Objective: To investigate the effect of bracket–ligature combination on the amount of orthodontic space closure over three months. Design: Randomized clinical trial with three parallel groups. Setting: A hospital orthodontic department (Chesterfield Royal Hospital, UK). Participants: Forty-five patients requiring upper first premolar extractions. Methods: Informed consent was obtained and participants were randomly allocated into one of three groups: (1) conventional pre-adjusted edgewise brackets and elastomeric ligatures; (2) conventional pre-adjusted edgewise brackets and Super Slick® low friction elastomeric ligatures; (3) Damon 3MX® passive self-ligating brackets. Space closure was undertaken on 0·019×0·025-inch stainless steel archwires with nickel–titanium coil springs. Participants were recalled at four weekly intervals. Upper alginate impressions were taken at each visit (maximum three). The primary outcome measure was the mean amount of space closure in a 3-month period. Results: A one-way ANOVA was undertaken [dependent variable: mean space closure (mm); independent variable: group allocation]. The amount of space closure was very similar between the three groups (1 mm per 28 days); however, there was a wide variation in the rate of space closure between individuals. The differences in the amount of space closure over three months between the three groups was very small and non-significant (P?=?0·718). Conclusion: The hypothesis that reducing friction by modifying the bracket/ligature interface increases the rate of space closure was not supported. The major determinant of orthodontic tooth movement is probably the individual patient response. PMID:23794696

Wong, Henry; Collins, Jill; Tinsley, David; Sandler, Jonathan; Benson, Philip

2013-01-01

373

Effects of long-term repeated topical fluoride applications and adhesion promoter on shear bond strengths of orthodontic brackets  

PubMed Central

Objective: The purpose of this study was to assess the effects of long-term repeated topical application of fluoride before bonding and an adhesion promoter on the bond strength of orthodontic brackets. Materials and Methods: A total of 76 bovine incisors were collected and divided equally into four groups. In group 1, the brackets were bonded without topical fluoride application or adhesion promoter. In group 2, before bonding, the adhesion promoter was applied to nonfluoridated enamel. In group 3, the brackets were bonded without the application of the adhesion promoter to enamel, which had undergone long-term repeated topical fluoride treatments. Teeth in group 4 received the long-term repeated topical applications of fluoride, and the brackets were bonded using the adhesion promoter. All the brackets were bonded using BeautyOrtho Bond self-etching adhesive. The shear bond strength was measured and the bond failure modes were evaluated with the use of the adhesive remnant index (ARI) after debonding. Results: The mean shear bond strength was significantly lower in group 3 than in groups 1, 2, and 4, and there were no significant differences between the groups except for group 3. There were significant differences in the distribution of ARI scores between groups 2 and 3, and between groups 3 and 4. Conclusions: The adhesion promoter can recover the bond strength reduced by the long-term repeated topical applications of fluoride to the prefluoridation level and had a significantly great amount of adhesives left on either fluoridated or nonfluoridated enamel. PMID:25512720

Endo, Toshiya; Ishida, Rieko; Komatsuzaki, Akira; Sanpei, Shinya; Tanaka, Satoshi; Sekimoto, Tsuneo

2014-01-01

374

Nonfunctionalized polydimethyl siloxane superhydrophobic surfaces based on hydrophobic-hydrophilic interactions.  

PubMed

Superhydrophobic surfaces based on polydimethyl siloxane (PDMS) were fabricated using a 50:50 PDMS-poly(ethylene glycol) (PEG) blend. PDMS was mixed with PEG, and incomplete phase separation yielded a hierarchic structure. The phase-separated mixture was annealed at a temperature close to the crystallization temperature of the PEG. The PEG crystals were formed isothermally at the PDMS/PEG interface, leading to an engineered surface with PDMS spherulites. The resulting roughness of the surface was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The PDMS spherulites, a few micrometers in diameter observed from SEM images, were found to have an undulated (rippled) surface with nanometer-sized features. The combination of micrometer- and nanometer-sized surface features created a fractal surface and increased the water contact angle (WCA) of PDMS more than 60°, resulting in a superhydrophobic PDMS surface with WCA of >160°. The active surface layer for the superhydrophobicity was approximately 100 ?m thick, illustrating that the material had bulk superhydrophobicity compared to conventional fluorocarbon or fluorinated coated rough surfaces. Theoretical analysis of the fractal surface indicates that the constructed surface has a fractal dimension of 2.5, which corresponds to the Apollonian sphere packing. PMID:21294505

Polizos, Georgios; Tuncer, Enis; Qiu, Xiaofeng; Aytu?, Tolga; Kidder, Michelle K; Messman, Jamie M; Sauers, Isidor

2011-03-15

375

Nonfunctionalized Polydimethyl Siloxane Superhydrophobic Surfaces Based on Hydrophobic-Hydrophilic Interactions  

SciTech Connect

Superhydrophobic surfaces based on polydimethyl siloxane (PDMS) were fabricated using a 50:50 PDM-poly(ethylene glycol) (PEG) blend. PDMS was mixed with PEG, and incomplete phase separation yielded a hierarchic structure. The phase-separated mixture was annealed at a temperature close to the crystallization temperature of the PEG. The PEG crystals were formed isothermally at the PDMS/PEG interface, leading to an engineered surface with PDMS spherulites. The resulting roughness of the surface was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The PDMS spherulites, a few micrometers in diameter observed from SEM images, were found to have an undulated (rippled) surface with nanometer-sized features. The combination of micrometer- and nanometer-sized surface features created a fractal surface and increased the water contact angle (WCA) of PDMS more than 60, resulting in a superhydrophobic PDMS surface with WCA of >160 degrees. The active surface layer for the superhydrophobicity was approximately 100 mu m thick, illustrating that the material had bulk superhydrophobicity compared to conventional fluorocarbon or fluorinated coated rough surfaces. Theoretical analysis of the fractal surface indicates that the constructed surface has a fractal dimension of 2.5, which corresponds to the Apollonian sphere packing.

Polizos, Georgios [Oak Ridge National Laboratory (ORNL); Tuncer, Enis [ORNL; Qiu, Xiaofeng [ORNL; Aytug, Tolga [ORNL; Kidder, Michelle [ORNL; Messman, Jamie M [ORNL; Sauers, Isidor [ORNL

2011-01-01

376

Pdf modeling for premixed turbulent combustion based on the properties of iso-concentration surfaces  

NASA Technical Reports Server (NTRS)

In premixed turbulent flames the presence of intense mixing zones located in front of and behind the flame surface leads to a requirement to study the behavior of iso-concentration surfaces defined for all values of the progress variable (equal to unity in burnt gases and to zero in fresh mixtures). To support this study, some theoretical and mathematical tools devoted to level surfaces are first developed. Then a database of direct numerical simulations of turbulent premixed flames is generated and used to investigate the internal structure of the flame brush, and a new pdf model based on the properties of iso-surfaces is proposed.

Vervisch, L.; Kollmann, W.; Bray, K. N. C.; Mantel, T.

1994-01-01

377

Friction and surface chemistry of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

The friction properties of some ferrous-base metallic glasses were measured both in argon and in vacuum to a temperature of 350 C. The alloy surfaces were also analyzed with X-ray photoelectron spectroscopy to identify the compounds and elements present on the surface. The results of the investigation indicate that even when the surfaces of the amorphous alloys, or metallic glasses, are atomically clean, bulk contaminants such as boric oxide and silicon dioxide diffuse to the surfaces. Friction measurements in both argon and vacuum indicate that the alloys exhibit higher coefficients of friction in the crystalline state than they do in the amorphous state.

Miyoshi, K.; Buckley, D. H.

1982-01-01

378

Surface impedance based microwave imaging method for breast cancer screening: contrast-enhanced scenario  

NASA Astrophysics Data System (ADS)

A new microwave imaging method that uses microwave contrast agents is presented for the detection and localization of breast tumours. The method is based on the reconstruction of breast surface impedance through a measured scattered field. The surface impedance modelling allows for representing the electrical properties of the breasts in terms of impedance boundary conditions, which enable us to map the inner structure of the breasts into surface impedance functions. Later a simple quantitative method is proposed to screen breasts against malignant tumours where the detection procedure is based on weighted cross correlations among impedance functions. Numerical results demonstrate that the method is capable of detecting small malignancies and provides reasonable localization.

Güren, Onan; Çayören, Mehmet; Tükenmez Ergene, Lale; Akduman, Ibrahim

2014-10-01

379

Land surface energy partitioning revisited: A novel approach based on single depth soil measurement  

NASA Astrophysics Data System (ADS)

partitioning of solar energy into sensible, latent, and ground heat fluxes over the land surface is responsible for changes of state variables in the soil-atmosphere system. Recent research enables the reconstruction of the land surface temperature and ground heat flux using Green's function approach, as well as the estimate of the distribution of available energy into latent and sensible heat fluxes based on linear stability analysis. Combining the Green's function approach and linear stability analysis, we propose a new physically based numerical procedure to estimate the land surface energy partitioning in this paper. The new method is capable of predicting all surface energy budgets using a single depth soil measurement; the model reliability is evaluated with comparisons to flux tower measurements. The results of this study deepen our insight into the implicit link between surface energy partition and subsurface soil dynamics and how the link can be employed to related research areas.

Yang, Jiachuan; Wang, Zhi-Hua

2014-12-01

380

Surface transport properties of Fe-based superconductors: The influence of degradation and inhomogeneity  

SciTech Connect

Surface properties of Co-doped BaFe{sub 2}As{sub 2} epitaxial superconducting thin films were inspected by X-ray photoelectron spectroscopy, scanning spreading resistance microscopy (SSRM), and point contact spectroscopy (PCS). It has been shown that surface of Fe-based superconductors degrades rapidly if being exposed to air, what results in suppression of gap-like structure on PCS spectra. Moreover, SSRM measurements revealed inhomogeneous surface conductivity, what is consistent with strong dependence of PCS spectra on contact position. Presented results suggest that fresh surface and small probing area should be assured for surface sensitive measurements like PCS to obtain intrinsic properties of Fe-based superconductors.

Plecenik, T.; Gregor, M.; Sobota, R.; Truchly, M.; Satrapinskyy, L.; Kus, P.; Plecenik, A. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia)] [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Kurth, F.; Holzapfel, B.; Iida, K. [Institute for Metallic Materials, IFW Dresden, P. O. Box 270116, D-01171 Dresden (Germany)] [Institute for Metallic Materials, IFW Dresden, P. O. Box 270116, D-01171 Dresden (Germany)

2013-07-29

381

Functional surface chemistry of carbon-based nanostructures  

NASA Astrophysics Data System (ADS)

The recently discovered abilities to synthesize single-walled carbon nanotubes and prepare single layer graphene have spurred interest in these sp2-bonded carbon nanostructures. In particular, studies of their potential use in electronic devices are many as silicon integrated circuits are encountering processing limitations, quantum effects, and thermal management issues due to rapid device scaling. Nanotube and graphene implementation in devices does come with significant hurdles itself. Among these issues are the ability to dope these materials and understanding what influences defects have on expected properties. Because these nanostructures are entirely all-surface, with every atom exposed to ambient, introduction of defects and doping by chemical means is expected to be an effective route for addressing these issues. Raman spectroscopy has been a proven characterization method for understanding vibrational and even electronic structure of graphene, nanotubes, and graphite, especially when combined with electrical measurements, due to a wealth of information contained in each spectrum. In Chapter 1, a discussion of the electronic structure of graphene is presented. This outlines the foundation for all sp2-bonded carbon electronic properties and is easily extended to carbon nanotubes. Motivation for why these materials are of interest is readily gained. Chapter 2 presents various synthesis/preparation methods for both nanotubes and graphene, discusses fabrication techniques for making devices, and describes characterization methods such as electrical measurements as well as static and time-resolved Raman spectroscopy. Chapter 3 outlines changes in the Raman spectra of individual metallic single-walled carbon nantoubes (SWNTs) upon sidewall covalent bond formation. It is observed that the initial degree of disorder has a strong influence on covalent sidewall functionalization which has implications on developing electronically selective covalent chemistries and assessing their selectivity in separating metallic and semiconducting SWNTs. Chapter 4 describes how optical phonon population extinction lifetime is affected by covalent functionalization and doping and includes discussions on static Raman linewidths. Increasing defect concentration is shown to decrease G-band phonon population lifetime and increase G-band linewidth. Doping only increases G-band linewidth, leaving non-equilibrium population decay rate unaffected. Phonon mediated electron scattering is especially strong in nanotubes making optical phonon decay of interest for device applications. Optical phonon decay also has implications on device thermal management. Chapter 5 treats doping of graphene showing ambient air can lead to inadvertent Fermi level shifts which exemplifies the sensitivity that sp2-bonded carbon nanostructures have to chemical doping through sidewall adsorption. Removal of this doping allows for an investigation of electron-phonon coupling dependence on temperature, also of interest for devices operating above room temperature. Finally, in Chapter 6, utilizing the information obtained in previous chapters, single carbon nanotube diodes are fabricated and characterized. Electrical performance shows these diodes are nearly ideal and photovoltaic response yields 1.4 nA and 205 mV of short circuit current and open circuit voltage from a single nanotube device. A summary and discussion of future directions in Chapter 7 concludes my work.

Abdula, Daner

382

Interactive object modelling based on piecewise planar surface patches?  

PubMed Central

Detecting elements such as planes in 3D is essential to describe objects for applications such as robotics and augmented reality. While plane estimation is well studied, table-top scenes exhibit a large number of planes and methods often lock onto a dominant plane or do not estimate 3D object structure but only homographies of individual planes. In this paper we introduce MDL to the problem of incrementally detecting multiple planar patches in a scene using tracked interest points in image sequences. Planar patches are reconstructed and stored in a keyframe-based graph structure. In case different motions occur, separate object hypotheses are modelled from currently visible patches and patches seen in previous frames. We evaluate our approach on a standard data set published by the Visual Geometry Group at the University of Oxford [24] and on our own data set containing table-top scenes. Results indicate that our approach significantly improves over the state-of-the-art algorithms. PMID:24511219

Prankl, Johann; Zillich, Michael; Vincze, Markus

2013-01-01

383

Peculiar surface behavior of some ionic liquids based on active pharmaceutical ingredients  

NASA Astrophysics Data System (ADS)

The ionic liquids based on biologically active cations and anions, commonly designated by ionic liquids based on active pharmaceutical ingredients (ILs-APIs), are interesting compounds for use in pharmaceutical applications. Lidocaine docusate, ranitidine docusate, and didecyldimethylammonium ibuprofen are examples of promising ILs-APIs that were recently synthesized. They were submitted to biological testing and calorimetric measurements, but nothing is known about their surface properties. In this work, we measured the surface tension and the contact angles on both hydrophilic and hydrophobic surfaces in a temperature range as wide as possible. Based on the wettability data, the polarity fractions were estimated using the Fowkes theory. The peculiar surface behavior observed was tentatively attributed to the presence of mesophases.

Restolho, José; Mata, José Luis; Saramago, Benilde

2011-02-01

384

A novel surface preparation methodology for epi-ready antimonide based III-V substrates  

NASA Astrophysics Data System (ADS)

Surfaces of GaSb substrates currently available from various commercial vendors are nowhere close to device grade GaAs, Si or InP wafer surfaces. Hence epitaxial growth and device fabrication on as-received commercial substrates poses significant difficulties amongst antimonide based researchers. Antimonide based materials are known to have poor surface oxide quality and not so well understood chemical reactions with various chemicals used to remove the oxides prior to growth. There are no existing reports on the detailed recipe for the preparation of "atomically flat and clean" surfaces that works on wafers obtained from various commercial vendors. This paper presents a detailed recipe for obtaining atomically flat and clean GaSb surfaces, irrespective of the initial polishing source. The same recipe (with slight modification) has been found to be successful with other III-V and II-VI compounds. The novel surface preparation process developed in our laboratory includes, chemical-mechanical polishing using an agglomerate-free sub-micron alumina slurry on a soft pad such as velvet, surface cleaning using dilute ammonium or potassium hydroxide-H2O solution and surfactant or glycerol, surface degreasing using organic solvents, oxide desorption using HCl-H2O and HF-H2O mixtures, mild chemical etching using ammonium sulfide and a final rinse in high purity deionized (DI) water and methanol. Using this recipe, we have been able to achieve surfaces with atomic flatness (RMS surface roughness close to 0.5 nm over a 10 x 10 mm2) and extremely clean surfaces, irrespective of the initial contamination or the sources of the wafers. Results of wafer surfaces before and after polishing using our recipe will be presented.

Dutta, P. S.; Rajagopalan, G.; Kim, H. J.; Kumar, A.

2005-05-01

385

Graphene-based textured surface by pulsed laser deposition as a robust platform for surface enhanced Raman scattering applications  

NASA Astrophysics Data System (ADS)

We have developed a surface enhanced Raman scattering (SERS)-active substrate based on gold nanoparticles-decorated few-layer (fl) graphene grown by pulsed laser deposition. Diamond-Like Carbon film has been converted to fl-graphene after thermal annealing at low temperature. The formation of fl-graphene was confirmed by Raman spectroscopy, and surface morphology was highlighted by scanning electron microscopy. We found that textured fl-graphene film with nanoscale roughness was highly beneficial for SERS detection. Rhodamine 6G and p-aminothiophenol proposed as test molecules were detected with high sensitivity. The detection at low concentration of deltamethrin, an active molecule of a commercial pesticide was further demonstrated.

Tite, T.; Donnet, C.; Loir, A.-S.; Reynaud, S.; Michalon, J.-Y.; Vocanson, F.; Garrelie, F.

2014-01-01

386

Graphene-based textured surface by pulsed laser deposition as a robust platform for surface enhanced Raman scattering applications  

SciTech Connect

We have developed a surface enhanced Raman scattering (SERS)-active substrate based on gold nanoparticles-decorated few-layer (fl) graphene grown by pulsed laser deposition. Diamond-Like Carbon film has been converted to fl-graphene after thermal annealing at low temperature. The formation of fl-graphene was confirmed by Raman spectroscopy, and surface morphology was highlighted by scanning electron microscopy. We found that textured fl-graphene film with nanoscale roughness was highly beneficial for SERS detection. Rhodamine 6G and p-aminothiophenol proposed as test molecules were detected with high sensitivity. The detection at low concentration of deltamethrin, an active molecule of a commercial pesticide was further demonstrated.

Tite, T.; Donnet, C.; Loir, A.-S.; Reynaud, S.; Michalon, J.-Y.; Vocanson, F.; Garrelie, F., E-mail: florence.garrelie@univ-st-etienne.fr [Université de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, F-42000 Saint-Etienne (France); and Université de Saint-Etienne, Jean Monnet, F-42000 Saint-Etienne (France)

2014-01-27

387

A Comparison of Shear Bond Strengths of Metal and Ceramic Brackets using Conventional Acid Etching Technique and Er:YAG Laser Etching  

PubMed Central

Background and aims. The aim of this study was to compare shear bond strength (SBS) of metal and ceramic brackets bonded to enamel using acid versus Er:YAG laser etching. Materials and methods. Eighty premolars were divided into 4 groups: AM (acid etching/ metal brackets), AC (acid etching/ ceramic brackets), LM (laser etching/ metal brackets) and LC (laser etching/ ceramic brackets). Enamel condition-ing was done using acid in AC and AM and Er:YAG laser in LC and LM. Brackets were debonded with a Dartec machine and the SBSs were determined. Adhesive remnant index was evaluated under a stereomicroscope. Two additional teeth were conditioned with acid and laser for scanning electron microscopy examination. Comparisons of SBS value were done by ANOVA test. Results. statistical analyses showed that SBSs of acid groups were significantly higher than that of laser groups, but dif-ferences between SBS values of AC/ AM and LC/LM were not significant. SEM examination revealed different etching pattern. Conclusion. Low power Er:YAG laser etching offers clinically acceptable SBS which besides its other superiorities to acid etching can be an appropriate alternative for bonding of ceramic brackets. PMID:25024836

Yassaei, Sogra; Fekrazad, Reza; Shahraki, Neda; Goldani Moghadam, Mahdjoube

2014-01-01

388

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

PubMed Central

Background The purpose of this study was to determine the bond strength of different orthodontic bracket materials (ceramic, stainless steel, and titanium) as well as stresses developed in bracket-cement-enamel systems using finite element (FE) analysis. Methods One hundred and thirty-five extracted human caries-free upper central incisors were divided into three groups (n?=?45/group) according to the type of orthodontic bracket materials (stainless steel, ceramic, and titanium). Each group was further subdivided into three subgroups (n?=?15/group) according to the bond strength test loading mode (shear short side, shear long side, and tensile). After debonding, the fractured specimen was examined, and the adhesive remnant index (ARI) was determined. FE analysis models analyzed the stress distribution within the cement and enamel. Bond strengths were analyzed using ANOVA and Tukey's test, and the ARI scores were analyzed using chi-square (?2) test. Results Shear loading at the short side of the bracket resulted in the highest bond strength and lowest maximum principal stress both on cement and enamel compared with the other loading modes (P?brackets presented with higher bond strength and lower maximum principal stress than metallic brackets (P?brackets (?2?=?64.852, P?brackets and the selection of orthodontic bracket materials affect the bond strength and stresses developed both on cement and enamel. PMID:24934213

2014-01-01

389

Solutions of half-space and half-plane contact problems based on surface elasticity  

NASA Astrophysics Data System (ADS)

Analytical solutions for the problems of an elastic half-space and an elastic half-plane subjected to a distributed normal force are derived in a unified manner using the general form of the linearized surface elasticity theory of Gurtin and Murdoch. The Papkovitch-Neuber potential functions, Fourier transforms and Bessel functions are utilized in the formulation. The newly obtained solutions are general and reduce to the solutions for the half-space and half-plane contact problems based on classical linear elasticity when the surface effects are not considered. Also, existing solutions for the half-space and half-plane contact problems based on simplified versions of Gurtin and Murdoch's surface elasticity theory are recovered as special cases of the current solutions. By applying the new solutions directly, Boussinesq's flat-ended punch problem, Hertz's spherical punch problem and a conical punch problem are solved, which lead to depth-dependent hardness formulas different from those based on classical elasticity. The numerical results reveal that smoother elastic fields and smaller displacements are predicted by the current solutions than those given by the classical elasticity-based solutions. Also, it is shown that the out-of-plane displacement and stress components strongly depend on the residual surface stress. In addition, it is found that the new solutions based on the surface elasticity theory predict larger values of the indentation hardness than the solutions based on classical elasticity.

Zhou, Songsheng; Gao, Xin-Lin

2013-02-01

390

Active illumination based 3D surface reconstruction and registration for image guided medialization laryngoplasty  

NASA Astrophysics Data System (ADS)

The medialization laryngoplasty is a surgical procedure to improve the voice function of the patient with vocal fold paresis and paralysis. An image guided system for the medialization laryngoplasty will help the surgeons to accurately place the implant and thus reduce the failure rates of the surgery. One of the fundamental challenges in image guided system is to accurately register the preoperative radiological data to the intraoperative anatomical structure of the patient. In this paper, we present a combined surface and fiducial based registration method to register the preoperative 3D CT data to the intraoperative surface of larynx. To accurately model the exposed surface area, a structured light based stereo vision technique is used for the surface reconstruction. We combined the gray code pattern and multi-line shifting to generate the intraoperative surface of the larynx. To register the point clouds from the intraoperative stage to the preoperative 3D CT data, a shape priori based ICP method is proposed to quickly register the two surfaces. The proposed approach is capable of tracking the fiducial markers and reconstructing the surface of larynx with no damage to the anatomical structure. We used off-the-shelf digital cameras, LCD projector and rapid 3D prototyper to develop our experimental system. The final RMS error in the registration is less than 1mm.

Jin, Ge; Lee, Sang-Joon; Hahn, James K.; Bielamowicz, Steven; Mittal, Rajat; Walsh, Raymond

2007-03-01

391

A survey of surface structures and subsurface developments for lunar bases  

NASA Technical Reports Server (NTRS)

Concepts proposed for lunar-base structures and shelters include those fabricated on earth, fabricated locally using lunar materials, and developed from subsurface features. Early bases may rely on evolutionary growth using Space Station modules and nodes covered with regolith for protection against thermal and radiative stresses. Expandable/inflatable shelters used alone on the surface or in conjunction with subselene (beneath the lunar surface) features and spent portions of the Space Shuttle's fuel tanks offer early alternatives. More mature lunar bases may need larger volumes provided by erectable buildings, hybrid inflatable/rigid spheres, modular concrete buildings using locally derived cement, or larger subselene developments.

Hypes, Warren D.; Wright, Robert L.

1990-01-01

392

Fast time-of-flight camera based surface registration for radiotherapy patient positioning  

SciTech Connect

Purpose: This work introduces a rigid registration framework for patient positioning in radiotherapy, based on real-time surface acquisition by a time-of-flight (ToF) camera. Dynamic properties of the system are also investigated for future gating/tracking strategies. Methods: A novel preregistration algorithm, based on translation and rotation-invariant features representing surface structures, was developed. Using these features, corresponding three-dimensional points were computed in order to determine initial registration parameters. These parameters became a robust input to an accelerated version of the iterative closest point (ICP) algorithm for the fine-tuning of the registration result. Distance calibration and Kalman filtering were used to compensate for ToF-camera dependent noise. Additionally, the advantage of using the feature based preregistration over an ''ICP only'' strategy was evaluated, as well as the robustness of the rigid-transformation-based method to deformation. Results: The proposed surface registration method was validated using phantom data. A mean target registration error (TRE) for translations and rotations of 1.62 {+-} 1.08 mm and 0.07 deg. {+-} 0.05 deg., respectively, was achieved. There was a temporal delay of about 65 ms in the registration output, which can be seen as negligible considering the dynamics of biological systems. Feature based preregistration allowed for accurate and robust registrations even at very large initial displacements. Deformations affected the accuracy of the results, necessitating particular care in cases of deformed surfaces. Conclusions: The proposed solution is able to solve surface registration problems with an accuracy suitable for radiotherapy cases where external surfaces offer primary or complementary information to patient positioning. The system shows promising dynamic properties for its use in gating/tracking applications. The overall system is competitive with commonly-used surface registration technologies. Its main benefit is the usage of a cost-effective off-the-shelf technology for surface acquisition. Further strategies to improve the registration accuracy are under development.

Placht, Simon; Stancanello, Joseph; Schaller, Christian; Balda, Michael; Angelopoulou, Elli [Metrilus GmbH, Henkestr. 91, 91052 Erlangen (Germany) and Pattern Recognition Lab, Friedrich Alexander University Erlangen-Nuremberg, Martensstr. 3, 91058 Erlangen (Germany); German Research Cancer Centre, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Metrilus GmbH, Henkestr. 91, 91052 Erlangen (Germany); Pattern Recognition Lab, Friedrich Alexander University Erlangen-Nuremberg, Martensstr. 3, 91058 Erlangen (Germany)

2012-01-15

393

Effect of Surface Nonequilibrium Thermochemistry in Simulation of Carbon Based Ablators  

NASA Technical Reports Server (NTRS)

This study demonstrates that coupling of a material thermal response code and a flow solver using finite-rate gas/surface interaction model provides time-accurate solutions for multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal Response and Ablation Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas momentum conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of gas/surface interaction chemistry between air and carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was a Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.

Chen, Yih-Kang; Gokcen, Tahir

2012-01-01

394

The Spinning Membrane, SUPER-SU(?)-GAUGE Theories and Moyal Brackets  

NASA Astrophysics Data System (ADS)

Several important topics concerning the membrane and its symmetries are discussed. The fact that a space-time-independent Lagrangian density for a gauge-field configuration of a (d - 1)-dimensional SU(?) super Yang-Mills theory, reduced to one dimension (time), is equivalent to a Green-Schwarz formalism of the Euclidean Eguchi-Schild string action in d - 1 dimensions, naturally raises the question whether one can construct a Neveu-Ramond-Schwarz analog. The answer is in the negative; the world-sheet supersymmetric extension of the Eguchi-Schild action for the string cannot be viewed as a classical-vacuum configuration of a super-SU(?)-gauge theory. For the second topic we construct a "supersymmetry" charge operator, Qf, which plays the role of a residual fermionic symmetry, for fixed time, of the light-cone spinning membrane. It is explicitly shown how the Yang-Mills type of actions and, in particular, the ones for vacuum-field configurations, associated with Q(?) supergauge theories, are invariant under both Qf "supersymmetry" and the superalgebra of area-preserving superdiffeomorphisms of the light-cone spinning torus membrane, Q(?). More general actions can be constructed which are invariant under deformations of this superalgebra. In this case the ordinary (graded) Poisson brackets are replaced by super Moyal brackets. Finally, we conjecture why these actions, in analogy with what happens with the light-cone supermembrane, should correspond to a superfiber bundle (over space-time) formulation of the supersymmetric-gauge quantum-mechanical models (SGQMM's) of Flume and Baake et al.; with the general supergroup of trigonometric structure constants of Fairlie, Fletcher and Zachos as the structure supergroup of the superfiber. To support our concluding conjecture, preliminary steps are outlined which are necessary in order to fix the light-cone gauge for the spinning-membrane action. We discuss why the Qf "supersymmetry" (the remnant world-volume light-cone local supersymmetry) and the Q(?) supergauge transformations must arise as its residual symmetries.

Castro, Carlos

395

Mapping surface energy balance components by combining Landsat Thematic Mapper and ground-based meteorological data  

NASA Technical Reports Server (NTRS)

Surface energy balance components were evaluated by combining satellite-based spectral data with on-site measurements of solar irradiance, air temperature, wind speed, and vapor pressure. Maps of latent heat flux density and net radiant flux density were produced using Landsat TM data for three dates. The TM-based estimates differed from Bowen-ratio and aircraft-based estimates by less than 12 percent over mature fields of cotton, wheat, and alfalfa.

Moran, M. Susan; Jackson, Ray D.; Raymond, Lee H.; Gay, Lloyd W.; Slater, Philip N.

1989-01-01

396

Functional specializations in human cerebral cortex analyzed using the Visible Man surface-based atlas  

NASA Technical Reports Server (NTRS)

We used surface-based representations to analyze functional specializations in the human cerebral cortex. A computerized reconstruction of the cortical surface of the Visible Man digital atlas was generated and transformed to the Talairach coordinate system. This surface was also flattened and used to establish a surface-based coordinate system that respects the topology of the cortical sheet. The linkage between two-dimensional and three-dimensional representations allows the locations of published neuroimaging activation foci to be stereotaxically projected onto the Visible Man cortical flat map. An analysis of two activation studies related to the hearing and reading of music and of words illustrates how this approach permits the systematic estimation of the degree of functional segregation and of potential functional overlap for different aspects of sensory processing.

Drury, H. A.; Van Essen, D. C.

1997-01-01

397

Phase-locked loop based on machine surface topography measurement using lensed fibers.  

PubMed

We present the phase-locked loop (PLL)-based metrology concept using lensed fibers for on-machine surface topography measurement. The shape of a single-mode fiber at the endface was designed using an ABCD matrix method, and two designed lensed fibers-the ball type and the tapered type-were fabricated, and the performance was evaluated, respectively. As a result, the interferometric fringe was not found in the case of the ball lensed fiber, but the machined surface could be measured by utilization of autofocusing and intensity methods. On the other hand, a very clear Fizeau interferometric fringe was observed in the case of the tapered lensed fiber. Its performance was compared with the results of the capacitance sensor and a commercially available white-light interferometer. We confirmed that PLL-based surface profile measurement using the tapered and ball lensed fibers can be applied for on-machine surface topography measurement applications. PMID:21283236

Kang, Jin-Ho; Lee, ChaBum; Joo, Jae-Young; Lee, Sun-Kyu

2011-02-01

398

Phase-locked loop based on machine surface topography measurement using lensed fibers  

SciTech Connect

We present the phase-locked loop (PLL)-based metrology concept using lensed fibers for on-machine surface topography measurement. The shape of a single-mode fiber at the endface was designed using an ABCD matrix method, and two designed lensed fibers--the ball type and the tapered type--were fabricated, and the performance was evaluated, respectively. As a result, the interferometric fringe was not found in the case of the ball lensed fiber, but the machined surface could be measured by utilization of autofocusing and intensity methods. On the other hand, a very clear Fizeau interferometric fringe was observed in the case of the tapered lensed fiber. Its performance was compared with the results of the capacitance sensor and a commercially available white-light interferometer. We confirmed that PLL-based surface profile measurement using the tapered and ball lensed fibers can be applied for on-machine surface topography measurement applications.

Kang, Jin-Ho; Lee, ChaBum; Joo, Jae-Young; Lee, Sun-Kyu

2011-02-01

399

Extraction of urban impervious surface information based on object-oriented technology  

NASA Astrophysics Data System (ADS)

Impervious surface is an important part of urban underlying surface, as well as an important monitoring index for city ecological system and environment changes. However, accurate impervious surface extraction is still a challenge. This paper uses the color, shape and overall heterogeneity features from the high spatial resolution remote sensing image to extract the impervious surface. An edge-based image segmentation algorithm is put forward to fuse heterogeneous objects which integrates edge features and multi-scale segmentation algorithm and uses the edge information to guide image objects generation. Results showed that this method can greatly improve the accuracy of image segmentation. Accuracy assessment indicated that the overall impervious surface classification accuracy and a Kappa coefficient yield 87% and 0.84, respectively.

Liu, Aixia; Zhao, Xiaojie; Wang, Jing; He, Ting

2013-10-01

400

A physical model based on surface potential for double-gate aSi:H TFTs  

Microsoft Academic Search

In this paper, a physical model based on surface potential is presented for double gate a-Si:H TFTs. Firstly, a new model for the distribution of potential and electrical field along the bulk a-Si:H layer is proposed when both the front and back gates are biased in the positive voltages. Using this model, the front and back surface potential can be

Yuan Liu; Ruo-He Yao; Bin Li; Wen-Niu Xie

2009-01-01

401

Acid–base chemistry of albite surfaces in aqueous solutions at standard temperature and pressure  

Microsoft Academic Search

Surface acidity of albite has been determined by potentiometric titration of water-washed and unwashed powders at 23.5°C and pH range of 2–9.5. Using NH4Cl as the background electrolyte the surface was titrated with HCl and NH4OH in both forward and backward directions. These titrants have the advantage of possessing the same acid- and base-radicals as those of the background electrolyte

Biswajit Mukhopadhyay; John V. Walther

2001-01-01

402

Band-Structure Based model for photoelectron emission from metal surfaces  

NASA Astrophysics Data System (ADS)

Photoelectron emission spectra induced by grazing incidence of intense and ultrashort laser pulses on a metal surface are studied within a distorted-wave formalism. The proposed aproximation, named Band-Structure Based-Volkov (BSB-V) approach, includes a precise description of the surface potential, incorporating information of the band structure of the solid. Results are compared with the numerical solution of the time-dependent Schrodinger equation and with values derived from simpler theoretical models.

Rios, C. A.; Gravielle, M. S.; Mitnik, D. M.; Silkin, V. M.

2012-11-01

403

Hyperspectral Observations of Land Surfaces Using Ground-based, Airborne, and Satellite Sensors  

Microsoft Academic Search

The University of Wisconsin-Madison Space Science and Engineering Center (UW-SSEC) has helped pioneer the use of high spectral resolution infrared spectrometers for application to atmospheric and surface remote sensing. This paper is focused on observations of land surface infrared emission from high spectral resolution measurements collected over the past 15 years using airborne, ground-based, and satellite platforms. The earliest data

R. O. Knuteson; F. A. Best; H. E. Revercomb; D. C. Tobin

2006-01-01

404

Fragment-based Evaluation of Non-Uniform B-spline Surfaces on GPUs  

Microsoft Academic Search

In this paper, we propose a fragment-based evaluation method for non-uniform B-spline surfaces using recent programmable graphics hardware (GPU). A position on a non-uniform B-spline surface is evaluated by the linear combination of both control points and B-spline basis functions. Hence the computational costs can be reduced by pre-computing a knot interval of a parameter from a knot vector. We

Takashi Kanai

2007-01-01

405

RESIDUAL STRESS ASSESSMENT IN SURFACE-TREATED NICKEL-BASE SUPERALLOYS  

Microsoft Academic Search

Experimental results are presented to illustrate that there exists a unique window of opportunity for eddy current NDE of residual stress in surface-treated nickel-base superalloys. In light of its frequency-dependent penetration depth, the measurement of eddy current conductivity has been suggested as a possible means to allow the nondestructive evaluation of subsurface residual stresses in surface-treated components. This technique is

M. P. Blodgett; P. B. Nagy

406

Microdetermination of silicon dioxide on the surface by sensors based on perfluorinated proton-conducting membranes  

NASA Astrophysics Data System (ADS)

A microdetermination method of silicon dioxide on the silicon surface is studied. In this method, a thin SiO2 layer is dissolved in an aqueous solution of hydrofluoric acid and then the resulting solution is analyzed with sensors based on perfluorinated proton-conducting membranes. Quantitative determination of silicon dioxide remaining on the silicon surface in a quantity as low as 1 × 10-6 mol is demonstrated to be feasible.

Nikitin, S. E.; Terukov, E. I.; Timofeev, S. V.; Manabaev, N. K.

2012-06-01

407

Characteristics of thin surface layers of cobalt-based alloys deposited by laser cladding  

Microsoft Academic Search

Thin surface layers of cobalt-based alloys (Stellite 6 and Tribaloy T-900) and 410 stainless steel (SS) were deposited on mild steel substrates by a coaxial laser cladding process. This process could produce a thin surface layer of less than 0.5 mm with low energy input. Laser-clad Stellite 6 and Tribaloy T-900 specimens exhibited refined dendritic microstructure. The interdendritic eutectics consisted

W. C. Lin; C. Chen

2006-01-01

408

Satellite Based Mapping of Land Surface ET using MODIS and Alternate Surface Meteorological Inputs from AMSR-E, Reanalysis, and Surface Weather Stations  

NASA Astrophysics Data System (ADS)

Regional evapotranspiration (ET), including water loss from plant transpiration and soil evaporation, is essential to understanding interactions between land-atmosphere surface energy and water balances. Vapor pressure deficit (VPD) and surface air temperature are key variables for stomatal conductance and ET estimation. We developed an algorithm to estimate ET using a modified Penman-Monteith approach driven by MODIS derived vegetation data and daily surface meteorological inputs including net incoming solar radiation, air temperature and VPD. The model was applied using alternate daily meteorological inputs, including: 1) site level weather station observations, 2) VPD and air temperature derived from the Advanced Microwave Scanning Radiometer (AMSR-E) on the EOS Aqua satellite, and 3) Global Modeling and Assimilation Office (GMAO) reanalysis based surface temperature, humidity and solar radiation data. Model performance was assessed across a North American boreal-Arctic transect (>50o N) of six eddy covariance flux towers representing boreal grassland, boreal forest and tundra biomes. Model results derived from the three meteorology data sets agree well with observed tower fluxes (r>0.6; P<0.00001; RMSE<30W/m2) and capture spatial patterns and seasonal variability in ET. The MODIS-AMSR-E derived ET results also show comparable accuracy to ET results derived from the reanalysis meteorology, while ET estimation error was generally more a function of algorithm parameterization than differences in meteorology drivers. Our results indicate significant potential for regional mapping and monitoring daily land surface evaporation using synergistic information from satellite optical-IR and microwave remote sensing.

Mu, Q.; Jones, L. A.; Kimball, J. S.; Running, S. W.

2007-12-01

409

Anamorphic microlens arrays based on breath-figure template with adaptive surface reconstruction  

NASA Astrophysics Data System (ADS)

We describe an approach for fabricating anamorphic microlens array films based on a microporous polymer film template created by self-assembly of condensed water droplets. By using a copolymer of hydrophobic and hydrophilic functionalities for the template material, we create an "environmentally responsive" surface. The hydrophilic groups attract water to create the microvoid pattern but upon heating and stretching in dry air the copolymer reorients to create a low surface energy "nonstick" surface. This enables a variety of polymer precursor materials to be coated on the template, cured, and released to provide anamorphic films with the proper mechanical and optical properties.

Chari, Krishnan; Lander, Charles W.; Sudol, Ronald J.

2008-03-01

410

Triton's surface properties - A preliminary analysis from ground-based, Voyager photopolarimeter subsystem, and laboratory measurements  

NASA Technical Reports Server (NTRS)

The surface properties of Triton were investigated using data from the ground-based and Voyager photopolarimeter subsystem (PPS) observations of Triton's phase curve. The results indicate that Triton has a high single-scattering albedo (0.96 +/-0.01 at 0.75 micron) and an unusually compacted surface, possibly similar to that of Europa. Results also suggest that Triton's single-particle phase function and the macroscopically rough character of its surface are similar to those of most other icy satellites.

Buratti, B. J.; Lane, A. L.; Gibson, J.; Burrows, H.; Nelson, R. M.; Bliss, D.; Smythe, W.; Garkanian, V.; Wallis, B.

1991-01-01

411

Surface characterization of collagen/elastin based biomaterials for tissue regeneration  

NASA Astrophysics Data System (ADS)

Collagen and elastin are the main proteins of extracellular matrix. Collagen plays a crucial role in tensile strength of tissues, whereas elastin provides resilience to many organs. Both biopolymers are readily available and biocompatible. These properties point out that collagen and elastin are good components of materials for many potential medical applications. The surface properties of biomaterials play an important role in biomedicine as the majority of biological reactions occur on the surface of implanted materials. One of the methods of surface modification is UV-irradiation. The exposition of the biomaterial on ultraviolet light can alterate surface properties of the materials, their chemical stability, swelling properties and mechanical properties as well. The aim of our work was to study the surface properties and biocompatibility of new collagen/elastin based biomaterials and consideration of the influence of ultraviolet light on these properties. The surface properties of collagen/elastin based biomaterials modified by UV-irradiation were studied using the technique of atomic force microscopy (AFM) and contact angle measurements. On the basis of the results the surface free energy and its polar component was calculated using Owens-Wendt method. To assess the biological performance of films based on collagen, elastin and their blends, the response of 3T3 cell was investigated. It was found that the surface of collagen/elastin film is enriched in less polar component - collagen. Exposition on UV light increases polarity of collagen/elastin based films, due to photooxidation process. The AFM images have shown that topography and roughness of the materials had been also affected by UV-irradiation. The changes in surface properties influence on interaction between the material's surface and cells. The investigation of 3T3 cells grown on films based on collagen, elastin and their blends, leads to the conclusion that higher content of elastin in biomaterial promotes the cell adhesion and their viability on the surface. Also the suitable dose of UV light (1, 2 h) improves the biocompatibility of the materials.

Skopinska-Wisniewska, J.; Sionkowska, A.; Kaminska, A.; Kaznica, A.; Jachimiak, R.; Drewa, T.

2009-07-01

412

Multi-dimensional respiratory motion tracking from markerless optical surface imaging based on deformable mesh registration  

NASA Astrophysics Data System (ADS)

Real-time optical surface imaging systems offer a non-invasive way to monitor intra-fraction motion of a patient's thorax surface during radiotherapy treatments. Due to lack of point correspondence in dynamic surface acquisition, such systems cannot currently provide 3D motion tracking at specific surface landmarks, as available in optical technologies based on passive markers. We propose to apply deformable mesh registration to extract surface point trajectories from markerless optical imaging, thus yielding multi-dimensional breathing traces. The investigated approach is based on a non-rigid extension of the iterative closest point algorithm, using a locally affine regularization. The accuracy in tracking breathing motion was quantified in a group of healthy volunteers, by pair-wise registering the thoraco-abdominal surfaces acquired at three different respiratory phases using a clinically available optical system. The motion tracking accuracy proved to be maximal in the abdominal region, where breathing motion mostly occurs, with average errors of 1.09 mm. The results demonstrate the feasibility of recovering multi-dimensional breathing motion from markerless optical surface acquisitions by using the implemented deformable registration algorithm. The approach can potentially improve respiratory motion management in radiation therapy, including motion artefact reduction or tumour motion compensation by means of internal/external correlation models.

Schaerer, Joël; Fassi, Aurora; Riboldi, Marco; Cerveri, Pietro; Baroni, Guido; Sarrut, David

2012-01-01

413

Biodegradable polyester-based microcarriers with modified surface tailored for tissue engineering.  

PubMed

Microcarriers have been proposed in tissue engineering, namely for bone, cartilage, skin, vascular, and central nervous system. Although polyester-based microcarriers have been already used for this purpose, their surface properties should be improved to provide better cell growth. The goal of this study was to prepare microbeads based on poly(d,l-lactide) acid, poly(l-lactide) acid, and to study cell behavior (adhesion, spreading, growth, and proliferation) in function of microbead topography and surface chemistry. To improve L-929 fibroblasts adhesion, microbead surface has been modified with three polycations: chitosan, poly(2-dimethylamino ethylmethacrylate) (PDMAEMA), or chitosan-g-oligolactide copolymer (chit-g-OLA). Although modification of the microbead surface with chitosan and PDMAEMA was performed through physical adsorption on the previously prepared microbeads, chit-g-OLA copolymer was introduced directly during microbead processing. This simple approach (1) bypass the use of an emulsifier (polyvinyl alcohol, PVA); (2) avoid surface "contamination" with PVA molecules limiting a control of the surface characteristics. In vitro study of the growth of mouse fibroblasts on the microbeads showed that both surface topography and chemistry affected cell attachment, spreading, and proliferation. Cultivation of L-929 fibroblasts for 7 days resulted in the formation of a 3D cell-scaffold network. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 939-948, 2015. PMID:24832052

Privalova, A; Markvicheva, E; Sevrin, Ch; Drozdova, M; Kottgen, C; Gilbert, B; Ortiz, M; Grandfils, Ch

2015-03-01

414

The role of surface treatments on the bond between acrylic denture base and teeth.  

PubMed

The aim of this study was to compare the bond strength between acrylic denture base and teeth subjected to 6 surface treatments. Ninety-six specimens were made with poly(methylmethacrylate) teeth bonded to a microwave-polymerized acrylic denture base material. The specimens were distributed into 6 groups (n=16) according to surface treatments: CT - no treatment (control); MN - methylmethacrylate monomer etching; AO - 50-microm-particle aluminum oxide air abrasion; BR - glaze removal with a round bur; ST - surface grinding with an aluminum oxide abrasive stone; group CV - cavity preparation (diatorics). The control and surface-treated groups were subjected to a compressive load at 45 masculine angle to the long axis of the teeth. Data were analyzed by one-way ANOVA, followed by Scheffé's test (p<0.05). Bond strength means and (SD) in kgf for groups were: CT: 18.19 (7.14), MN: 18.34 (5.28), AO: 23.82 (5.40), BR: 23.30 (4.79), ST: 25.39 (7.80) and CV: 17.48 (7.17). There was statistically significant difference (p=0.037997) only between ST and CV. In conclusion, ridge lap surface grinding with an aluminum oxide abrasive stone provided the highest bond strength, though it differed significantly only when compared to diatorics. The other surface treatments provided similar bond between the acrylic denture base and teeth. PMID:19738950

Bragaglia, Lauro Egídio; Prates, Luiz Henrique Maykot; Calvo, Maria Cristina Marino

2009-01-01

415

Interaction of preosteoblasts with surface-immobilized collagen-based nanotubes.  

PubMed

In a previous work, we demonstrated the successful use of electrophoretic deposition (EPD) to immobilize collagen-based nanotubes onto indium-tin-oxide-coated glass (ITO glass), leading to the creation of biointerfaces with protein-based chemistry and topography [1]. In this work, we present a first study of preosteoblasts behavior in contact with surface-immobilized collagen-based nanotubes. Changes in cell morphology after their interaction with ITO glass modified with collagen-based nanotubes were studied using fluorescence microscopy and compared to those observed on virgin ITO glass as well as on ITO glass on which a collagen layer was simply adsorbed. Scanning electron microscopy (SEM) was used to study interactions of cell filopodias with the deposited nanotubes. Cytotoxicity of these biointerfaces was examined as well in short term cultures, using Alamar blue assay. Cells showed particular morphologies on ITO glass coated with nanotubes compared to virgin ITO glass or collagen adsorbed layer on ITO glass. High resolution SEM images suggest that apart from cell morphology, length and thickness of filopodias seem to be significantly affected by surface modification with collagen-based nanotubes. Moreover, nanotube-coated ITO glass did not show any obvious cytotoxicity in short term culture, opening new perspectives for the surface modification of biomaterials. We show the versatility of the proposed surface modification procedure by tailoring biointerfaces with a mixture of micro- and nanometer-scale collagen-based tubes. PMID:23792554

Kalaskar, Deepak M; Demoustier-Champagne, Sophie; Dupont-Gillain, Christine C

2013-11-01

416

Dielectrophoresis-Based Discrimination of Bacteria at the Strain Level Based on Their Surface Properties  

E-print Network

Insulator-based dielectrophoresis can be used to manipulate biological particles, but has thus far found limited practical applications due to low sensitivity. We present linear sweep three-dimensional insulator-based ...

Willner, Dana

417

An implicit evolution scheme for active contours and surfaces based on IIR filtering.  

PubMed

In this work, we present an approach for implementing an implicit scheme for the numerical solution of the partial differential equation of the evolution of an active contour/surface. The proposed scheme is applicable to any variant of the traditional active contour (AC), irrespectively of the calculation of the image-based force field and it is readily applicable to explicitly parameterized active surfaces (AS). The proposed approach is formulated as an infinite impulse response (IIR) filtering of the coordinates of the contour/surface points. The poles of the filter are determined by the parameters controlling the shape of the active contour/surface. We show that the proposed IIR-based implicit evolution scheme has very low complexity. Furthermore, the proposed scheme is numerically stable, thus it allows the convergence of the AC/AS with significantly fewer iterations than the explicit evolution scheme. It also possesses the separability property along the two parameters of the AS, thus it may be applied to deformable surfaces, without the need to store and invert large sparse matrices. We implemented the proposed IIR-based implicit evolution scheme in the Vector Field Convolution (VFC) AC/AS using synthetic and clinical volumetric data. We compared the segmentation results with those of the explicit AC/AS evolution, in terms of accuracy and efficiency. Results show that the VFC AC/AS with the proposed IIR-based implicit evolution scheme achieves the same segmentation results with the explicit scheme, with considerably less computation time. PMID:24637146

Delibasis, Konstantinos K; Asvestas, Pantelis A; Kechriniotis, Aristides I; Matsopoulos, George K

2014-05-01

418

Lithium-based surfaces controlling fusion plasma behavior at the plasma-material interface  

SciTech Connect

The plasma-material interface and its impact on the performance of magnetically confined thermonuclear fusion plasmas are considered to be one of the key scientific gaps in the realization of nuclear fusion power. At this interface, high particle and heat flux from the fusion plasma can limit the material's lifetime and reliability and therefore hinder operation of the fusion device. Lithium-based surfaces are now being used in major magnetic confinement fusion devices and have observed profound effects on plasma performance including enhanced confinement, suppression and control of edge localized modes (ELM), lower hydrogen recycling and impurity suppression. The critical spatial scale length of deuterium and helium particle interactions in lithium ranges between 5-100 nm depending on the incident particle energies at the edge and magnetic configuration. Lithium-based surfaces also range from liquid state to solid lithium coatings on a variety of substrates (e.g., graphite, stainless steel, refractory metal W/Mo/etc., or porous metal structures). Temperature-dependent effects from lithium-based surfaces as plasma facing components (PFC) include magnetohydrodynamic (MHD) instability issues related to liquid lithium, surface impurity, and deuterium retention issues, and anomalous physical sputtering increase at temperatures above lithium's melting point. The paper discusses the viability of lithium-based surfaces in future burning-plasma environments such as those found in ITER and DEMO-like fusion reactor devices.

Allain, Jean Paul; Taylor, Chase N. [School of Nuclear Engineering, Purdue University, 400 Central Avenue, West Lafayette, Indiana 47907 (United States)

2012-05-15

419

Improving long time behavior of Poisson bracket mapping equation: A non-Hamiltonian approach  

SciTech Connect

Understanding nonadiabatic dynamics in complex systems is a challenging subject. A series of semiclassical approaches have been proposed to tackle the problem in various settings. The Poisson bracket mapping equation (PBME) utilizes a partial Wigner transform and a mapping representation for its formulation, and has been developed to describe nonadiabatic processes in an efficient manner. Operationally, it is expressed as a set of Hamilton's equations of motion, similar to more conventional classical molecular dynamics. However, this original Hamiltonian PBME sometimes suffers from a large deviation in accuracy especially in the long time limit. Here, we propose a non-Hamiltonian variant of PBME to improve its behavior especially in that limit. As a benchmark, we simulate spin-boson and photosynthetic model systems and find that it consistently outperforms the original PBME and its Ehrenfest style variant. We explain the source of this improvement by decomposing the components of the mapping Hamiltonian and by assessing the energy flow between the system and the bath. We discuss strengths and weaknesses of our scheme with a viewpoint of offering future prospects.

Kim, Hyun Woo; Rhee, Young Min, E-mail: ymrhee@postech.ac.kr [Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang 790-784, Korea and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

2014-05-14

420

Evolution of microstructure and magnetic properties in Co-Pt alloys bracketing the eutectoid composition  

NASA Astrophysics Data System (ADS)

This work correlates the evolution of magnetic properties with microstructure for aging of Co-Pt alloys with compositions bracketing the A1?L10+L12 eutectoid at about 60 at% Pt. The magnetic properties of Co41.7Pt58.3 were observed to vary intricately with annealing time and temperature, corresponding to changes in microstructural lengthscales, phase fractions, and degree of ordering. This alloy exhibited a maximum coercivity of 4 kOe and a maximum remanence ratio of 0.8, occurring at an early stage of transformation when strained L10 nanoparticles are embedded in the A1 matrix. For particle sizes below 40 nm, robust exchange coupling is observed. Although the L10 nanoparticles are rigorously below the single-domain critical size for zero applied field, we argue that a form of domain wall pinning controls magnetization reversal in the peak coercivity sample. After extended aging that completely consumes the A1 phase, quantitative x-ray analysis indicates that the L12 phase is also present, suggesting that two-phase region is broader than expected. Samples with composition Co37.6Pt62.4 formed only soft ferromagnetic L12 upon aging.

Ghatwai, P.; Vetter, E.; Hrdy, M.; Soffa, W. A.; Floro, J. A.

2015-02-01