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1.
Effect of ceramic veneer thickness and cement shade on the CIELAB system after bonding—an in vitro study
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Javier Montero Cristina Gómez‐Polo Juan Antonio Santos 《Color research and application》2016,41(6):642-648
In restoration dentistry clinicians need to control the effect of the ceramic thickness and cement shade to achieve successful colorimetric results when all‐ceramic veneers are bonded. The purpose of this study was to evaluate the in vitro effects of cement color and the thickness of the final shade on porcelain discs. The study sample comprised 120 e.max Press HT A‐2 ceramic discs of two thicknesses (60 of 1 mm thick and 60 of 0.5 mm thick). Three different lightnesses of Variolink Veneer cement were used (?3, 0, and +3) for the cementation process. An Easyshade spectrophotometer was used to measure color coordinates (L*, C*, h, a*, and b*) on the discs both before and after cementation. To a large extent, color changes (ΔE ) after the cementation process were found to depend on cement thickness, ceramic thickness, and cement lightness. This model predicted 52% of the observed variability. The most marked change in color appeared on discs 0.5 mm thick and a cement lightness of ?3 (ΔE = 12.0 units). By contrast, color was more stable (minor changes) on discs with a cement lightness of +3 (ΔE = 2.3 units). All color coordinates were significantly modified after bonding, both on thin and thick discs and in all three cement color groups (?3, 0, and +3). However the difference in color (ΔE ) is significantly greater in discs 0.5 mm thick as compared with ceramic discs 1 mm thick. The most prominent change after bonding was found in the h (hue) coordinate. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 642–648, 2016 相似文献
2.
Color stability of denture shade tabs is affected by exposure to daylight and decontamination protocols
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Eduardo José Soares Rafaella Tonani Marta Maria Martins Giamatei Contente Carolina Noronha Ferraz Arruda Fernanda de Carvalho Panzeri Pires‐de‐Souza 《Color research and application》2018,43(5):779-784
The purpose of this study was to investigate the effect of light exposure and decontamination protocols on the color stability of denture shade guide tabs. Fifty tabs for shades 62, 66, and 69 (Biotone IPN, Dentsply Sirona) were submitted to baseline L*a*b* measurements (EasyShade, Vita), separated into 5 experimental groups (n = 10), and subjected to one of the following conditions: G1–distilled water (DW‐H2O)–control; G2 ?70% alcohol; G3–sodium hypochlorite 1% (NaClO); G4–no light exposure; G5–natural light exposure for 6 months. The experimental conditions were designed to simulate 6 months of clinical use. After the test period, final color measurements were recorded. The mean tristimulus coordinate difference (ΔL*,Δa*,Δb*) and total color difference values () were analyzed using 2‐way ANOVA and the Tukey test, α = .05. G2 (alcohol) produced less (P < .05) color change in shade 69 than G3 (NaClO). G5 (light exposure) affected the color stability for all shades, producing a statistical difference (P < .05) from G4 (no light exposure). It was concluded that natural light changes the color stability of the shade guides and that decontamination with 70% alcohol had the least impact on the color stability of the shade guide tabs. 相似文献
3.
Patarin Wongsompipatana Mitsuo Ikeda Pichayada Katemake 《Color research and application》2013,38(4):267-276
People get cataract in their eyes when they age. The color perceived by the senile cataract eyes desaturates because of the environment light that scatters in the eyes by the hazy crystalline lenses. We investigated the effect of the desaturation on brightness of objects in terms of the equivalent lightness , which is composed of the achromatic lightness and the chromatic lightness . If the color desaturates, becomes smaller and consequently becomes smaller in the cataract eyes. with and without cataract experiencing goggles at room illuminances to cover mesopic to photopic level was measured. Red, yellow, green, and blue patches of size 2° × 2° arc of the visual angle were investigated with the direct heterochromatic brightness matching between the color patches and a gray scale. Both took about the same value. with goggles was then transferred to the final where the matching gray scale was observed without goggles to express the equivalent lightness of cataract eyes by the gray scale perceived by normal eyes. with goggles was lower than without goggles by about 10 L* units in all the four colors. This reduction was almost equal to the reduction of L* by the reduced transmittance of the goggles showing that there was no effect of color desaturation. The color appearance in the color patches was measured by the elementary color naming method, and the results clearly showed the color desaturation with goggles implying decrease of . We concluded that the scattered environment light compensated the decrease of to keep the brightness of stimuli unchanged. © 2011 Wiley Periodicals, Inc. Col Res Appl, 38, 267–276, 2013 相似文献
4.
Roy S. Berns 《Color research and application》2014,39(4):322-330
CIE L*, a*, b* is a rectangular coordinate system used extensively for numerical color communication and quality assurance. Often the a*, b* coordinates are rotated to cylindrical polar coordinates of (radial distance) and hab (angle measured counterclockwise from the a* axis), reasonably relating to chroma and hue. When each coordinate is considered independently, it is observed that colors in our daily experiences do not change in a similar independent fashion. Changes in concentration for mixtures of colorants result in changes in both chroma and lightness. Directly illuminated three‐dimensional colored objects change in both chroma and lightness between direct illumination and either shadow or highlight. Two new coordinates are defined for CIELAB: vividness, , and depth, . Each represents a Euclidean distance from a color defined by L* and to of 0 and either L* = 0 for vividness or L* = 100 for depth. Image‐based visualizations were made to demonstrate how changes in these variables led to color changes more representative of our daily experiences. For cases where a color and background had the same lightness, it was observed that colors became less distinct with a reduction in chroma. A third dimension was defined, clarity, , a Euclidean distance from a color defined by L*, a*, and b* to its background color, similarly defined. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 322–330, 2014 相似文献
5.
Counterion-Induced Cationic Flexible Nanoparticle Catalytic of Piperidinolysis of Phenyl Salicylate
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Muhammad Azri Mohd Noh Khalisanni Khalid Azhar Ariffin M. Niyaz Khan 《Journal of surfactants and detergents》2017,20(5):1075-1084
The removal of PSa? from bulk aqueous phase to the pseudo‐micellar phase by halobenzoate counterion X is responsible for the monotonic increase in kobs (pseudo first‐order rate constants) with the increase in the values of [MX] where MX = sodium salts of 2‐, and 4‐halobenzoic acids. The values of ion exchange constants, or for X = 2‐ and 4‐halobenzoate ions in the presence of tetradecyltrimethylammonium bromide (TTABr) were calculated from the apparent catalytic rate constants, Xkcat which represent the catalytic effect of CFN. Larger values of or were observed for X = 4‐halobenzoate ions than that for X = 2‐halobenzoate ions due to isomeric factors. The values of or determined in the presence of TTABr were compared with previously determined or values in the presence of cetyltrimethylammonium bromide (CTABr). The values of or are nearly 8 ~ 9‐fold larger for 4‐IBz?, 4‐BrBz? and 4‐ClBz? compared to the respective values of X = 2‐IBz?, 2‐BrBz? and 2‐ClBz?. The values of or for X = 4‐FBz? is nearly 3‐fold larger than that for X = 2‐FBz?. The values of or for X = 2‐ and 4‐halobenzoates are significantly smaller in the presence of TTABr than these in the presence of CTABr nanoparticles. 相似文献
6.
The role of wettability of nonideal nozzle plate: From drop‐on‐demand droplet jetting to impact on solid substrate
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Lei Zhang Tao Ku Jingsong Jia Xiaoding Cheng 《American Institute of Chemical Engineers》2018,64(7):2837-2850
The dynamics of drop‐on‐demand (DoD) droplet formation and subsequently impact on the solid substrate are investigated using a three‐dimensional (3‐D) multirelaxation‐time (MRT) pseudopotential lattice Boltzmann (LB) model. The wettability of nonideal nozzle plate and solid substrate is modeled by a geometric scheme within the LB framework. The dynamics of droplet formation are explored in a range of the inverse of Ohnesorge number , , and , and the Reynolds number , , and . For , no satellite droplet is observed and the wettability of nozzle plate greatly influences the velocity and length of jetting fluids. For , the filament breakup and recombination are observed. The moment of filament breakup is delayed with advancing contact angle increasing. For with , the primary and satellite droplets could not be recombined with and which agree with the literature. Whereas with , the recombination occurs. The dynamics of subsequent oscillating droplet impact on the substrate are similar to that of equilibrium droplet which could obtain high‐resolution printed features. Consequently, considering with large and numbers, the printable range could be extended which could help increase the printing frequency and boost the production outputs of inkjet printing. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2837–2850, 2018 相似文献
7.
First‐Principles Study of Sc1−xTixF3 (x ≤ 0.375): Negative Thermal Expansion,Phase Transition,and Compressibility
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Lei Wang Cong Wang Ying Sun Sihao Deng Kewen Shi Huiqing Lu Pengwei Hu Xiaoyun Zhang 《Journal of the American Ceramic Society》2015,98(9):2852-2857
We present the first‐principles investigation of (x ≤ 0.375). Controllable thermal expansion of is achieved by different Ti contents. The negative thermal expansion (NTE) behavior is weakened gradually with increasing Ti content, which is consistent with experimental measurements. The Jahn–Teller effect plays an important role in the cubic‐to‐rhombohedral phase transition, which stems from the enhanced energy stability when the 3d orbitals of cation split into triply degenerate and sets. The unusual thermal stiffening of is found, which is similar to that of and but contrary to other NTE materials. 相似文献
8.
Cristina Gómez‐Polo Miguel Gómez‐Polo Juan Antonio Martínez Vázquez De Parga Alicia Celemín‐Viñuela 《Color research and application》2015,40(2):194-200
To find out whether the 26 shade tabs of the Toothguide 3D Master can be grouped according to the five groups of lightness proposed by the manufacturer (Vita‐Zahnfabrik) the three color coordinates L*, C*, and h were studied. Upper central incisor color was measured through the Easyshade Compact spectrophotometer using 1361 participants aged between 16 and 89. The color of the middle third was registered in the Toothguide 3D Master nomenclature and in the CIELCh‐system. Principal Component Analysis and Cluster analysis, were applied for data processing. The statistical analysis reveals the existence of five cluster groups. Cluster 1 comprises samples 1M1 ‐ 2L1.5 ‐ 2M1 ‐ 2R1.5 ‐ 3L1.5 ‐ 3M1. Cluster 2 comprises 1M2 ‐ 2L2.5 ‐ 2M2 ‐ 2M3 ‐ 2R2.5 ?3M2 ‐ 3L2.5. Cluster 3 comprises 3R1.5 ‐ 4L1.5 ‐ 4L2.5 ‐ 4M1 ‐ 4M2 ‐ 4R1.5 ‐ 5M1. Cluster 4 comprises 3M3 ‐ 3R2.5 ‐ 4M3 ‐ 4R2.5. And, finally, Cluster 5 comprises: 5M2 ‐ 5M3. The 26 shade tabs in the Toothguide 3D Master can be grouped into five clusters following coordinates L*, C*, and h resulting from the dental spectrophotometer Vita Easyshade compact. The shade tabs that compose each cluster do not belong to the same lightness group. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 194–200, 2015 相似文献
9.
Synthesis of aminated glycidyl methacrylate grafted rice husk and investigation of its anion‐adsorption properties
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In this study, we focused on the synthesis, characterization, and adsorption capacity testing of aminated glycidyl methacrylate grafted rice husk (RH‐g‐GMA–Am). Our goal was to obtain a high‐performance surface for the adsorption of various anions. Glycidyl methacrylate grafted rice husk (RH‐g‐GMA) was prepared by the graft copolymerization of glycidyl methacrylate with rice husk; the product was further subjected to an amination reaction. The surface properties, sorption characteristic functional groups, isotherm and kinetic studies, pore diffusion models, and effects of the temperature and pH on the material properties were studied under batch conditions. The IR spectroscopy results show additional surface functional groups for RH‐g‐GMA–Am. The adsorptions of and on RH‐g‐GMA–Am were found to follow pseudo‐second‐order kinetics; this indicated a possible dominant role played by chemisorption. The rate‐limiting step for mass transfer was found to be boundary layer diffusion. Furthermore, the sorption isotherms for and fit the Langmuir model. The amination of RH‐g‐GMA drastically increased the removal efficiency from 3 to 82% and from 6 to 93% for and , respectively. Moreover, RH‐g‐GMA–Am exhibited a better removal efficiency in the pH range of 4–6.5. Regeneration studies revealed that the surface of RH‐g‐GMA–Am could be regenerated repetitively by simple acid washing with an insignificant decrease in the active surface for consecutive adsorptions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43002. 相似文献
10.
Grain Boundary Curvatures Measurements in Annealed Yttria‐Stabilized Zirconia (3Y‐TZP) and Their Relation to Mean Grain Size
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It was determined that the mean grain boundary radius of curvature in 3 mol% yttria‐stabilized zirconia isothermally annealed without and with a DC electric field = 18 V/cm was uniquely proportional to the mean linear intercept grain size , the proportionality constant α = 3/2 being in accord with the Rios‐Fonseca stereological model. 相似文献
11.
Jongseong Park Dae‐Hyeon Kim Su‐Jin Park Tae‐gon Lee Mir Im Jeong‐Seog Kim Sahn Nahm 《Journal of the American Ceramic Society》2016,99(7):2229-2232
A specimen having a stoichiometric composition of KSbO3·(KSb) calcined at 800°C has an R rhombohedral structure (RS), and changes to a Pn cubic structure (CS) when calcined at 1100°C. Finally, a <111>‐oriented rhombohedral phase is formed in the specimen calcined at 1230°C. K/Sb ratio decreases from 1.0 in RS, 0.93 in CS, and finally to 0.85 in <111>‐oriented rhombohedral phases. On the other hand, a specimen having a K‐excess composition of K1.1SbO3 calcined at 800°C shows a RS that is maintained in the K‐excess specimen calcined at 1230°C. The composition of these specimens is very close to KSb. Therefore, the RS with a space group of R is a stable form of KSbO3. The formation of Pn cubic and <111>‐oriented R phases can be explained by the evaporation of K2O during the calcination process at temperatures above 1100°C. 相似文献
12.
M. M. de Beer J. T. F. Keurentjes J. C. Schouten J. van der Schaaf 《American Institute of Chemical Engineers》2016,62(10):3763-3773
Boiling of a pure fluid inside the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, average temperature driving force and mass flow rate . The average boiling heat transfer coefficient hb increases a factor 3 by increasing ω up to 105 rad s?1, independently of and . The performance of the srs‐SDR, in terms of hb vs. specific energy input ?, is similar to tubular boiling, where pressure drop provides the energy input. The srs‐SDR enables operation at Wm , yielding values of hb not practically obtainable in passive evaporators, due to prohibitively high pressure drops required. Since hb is increased independently of the superficial vapor velocity, hb is not a function of and the local vapor fraction. Therefore, the srs‐SDR enables a higher degree of control and flexibility of the boiling process, compared to passive flow boiling. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3763–3773, 2016 相似文献
13.
Removal of NO from flue gas using UV/S2
process in a novel photochemical impinging stream reactor
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A novel photochemical impinging stream reactor was developed for the first time. Removal process of NO from flue gas using sulfate radical ( ·) and hydroxyl radical (·OH) from UV‐light activation of persulfate (UV/S2 advanced oxidation process) was investigated in the novel reactor. Experiments were conducted to evaluate the effects of S2 concentration, solution pH, UV power, solution temperature, liquid‐gas ratio, flue gas flow, NO, SO2,and O2 concentrations on removal of NO. Mechanism and kinetics of NO removal were also studied. The results show that increasing UV power, solution temperature, S2 concentration, or solution circulation rate promotes NO removal. Increasing solution pH (1.2–11.9), NO concentration or flue gas flow weakens NO removal. O2 concentration has no significant effect on NO removal. · and ·OH were the major active species for NO removal. Absorption rate equation and kinetic parameters of NO removal were obtained. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2968–2980, 2017 相似文献
14.
Synthesis,Characterization and Aqueous Properties of a New Hybrid Fluorocarbon Cationic Surfmer
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YuJu Che Qing Gao Meiling Fang Yebang Tan Xiaoli Wang Fanjun Meng 《Journal of surfactants and detergents》2015,18(2):233-244
A novel hybrid fluorocarbon cationic surfmer has been synthesized and its aggregation and surface properties have been studied by surface tension, electrical conductivity, steady‐state fluorescence, Rayleigh light scattering, dynamic light scattering and transmission electron microscopy. Through surface tension, electrical conductivity, steady‐state fluorescence and Rayleigh light scattering measurements, the effectiveness of surface tension reduction, the maximum surface excess concentration, the minimum area occupied per surfactant molecule at the air/water interface, the micropolarity and aggregation number of micelles were investigated. The results shows that the surfmer has superior surface activity and lower micropolarity than other surfmers. The critical micelle concentration at different temperatures and a series of thermodynamic parameters (, , and , , , and ) of micellization were evaluated. The thermodynamic parameters showed that the micelle formation was entropy‐driven in the temperature range of 15–40 °C. The size and morphology of the aggregates were also confirmed by dynamic light scattering and transmission electron microscopy. 相似文献
15.
Effect of Oxygen Vacancy on Electrical Property of Acceptor Doped BaTiO3–Na0.5Bi0.5TiO3–Nb2O5 X8R Systems
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Yue Sun Hanxing Liu Hua Hao Shujun Zhang 《Journal of the American Ceramic Society》2016,99(9):3067-3073
In this study, we reported a new BaTiO3–Na0.5Bi0.5TiO3–Nb2O5–Mn2O3/Fe2O3/Co3O4/In2O3 X8R system with high dielectric constant (>2100) at room temperature. The impacts of oxygen vacancy ( ) on dielectric, electrical conductivity, and ferroelectric properties were systematically studied. The Curie point is largely depended on the concentration, which can be confirmed by the dielectric behavior and A1g octahedral breathing modes in Raman spectrum. In addition, the activation energy of diffusion is greatly reduced with the increase in concentration. It was found that the remnant polarization and coercive field were both decreased with increasing concentration, due to the facilitated defect dipoles reorientation and domain switching. 相似文献
16.
Confirmation of the Dominant Defect Mechanism in Amorphous In–Zn–O Through the Application of In Situ Brouwer Analysis
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Stephanie L. Moffitt Alexander U. Adler Thomas Gennett David S. Ginley John D. Perkins Thomas O. Mason 《Journal of the American Ceramic Society》2015,98(7):2099-2103
The dominant point defect mechanism of amorphous (a‐) indium zinc oxide (IZO) was probed through in situ electrical characterization of sputtered a‐IZO thin films in response to changes in oxygen partial pressure (pO) at 300C. The results yielded a power law dependence of conductivity (σ) versus pO of ~?1/6. This experimental method, known as Brouwer analysis, confirms doubly‐charged oxygen vacancies as the dominant defect species in a‐IZO. The success of this study suggests that Brouwer analysis is a viable method for studying the defect mechanisms of amorphous oxides. 相似文献
17.
Natural convection inside heated channel of a facility representing prismatic modular reactor core
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Mahmoud M. Taha Ibrahim A. Said Shoaib Usman Muthanna H. Al‐Dahhan 《American Institute of Chemical Engineers》2018,64(9):3467-3478
The newly developed Plenum‐to‐Plenum facility (P2PF) at Missouri S&T has shown to be an innovative separate effects test facility representing the geometry of prismatic modular reactors. Thermal and velocity fields inside this dual channel facility have been investigated under different natural circulation intensities. It is found that temperature and velocity profiles are function of the measurements locations and the amount of heat supplied to the channel. Quantification of the overall Rayleigh number versus overall Reynold number are found to be related by . Upper plenum mixing was characterized by determining the modified Reynold number and Froude number dimensionless groups. Analysis of these dimensionless groups along with observable turbulence amplifications emphasize relevance of adopting axial temperature inflection as a criterion for initiation of naturally driven flow destabilization inside vertical heated channels. Additionally, quantification of the distortion factors for characteristic dimensionless groups reveal a good similarity between the P2PF and the Modular High Temperature Gas‐cooled Reactor. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3467–3478, 2018 相似文献
18.
The influence of injection velocity and relaxation time on the spreading of tracers in viscoelastic liquids agitated by submerged,recirculating jets with low reynolds numbers
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Pradipto K. Bhattacharjee Stephen P. Kennedy Qian Xu Nicky Eshtiaghi Rajarathinam Parthasarathy 《American Institute of Chemical Engineers》2017,63(7):3132-3140
We provide experimental demonstration that the spread of tracer elements in a tank containing a viscoelastic liquid and agitated by a submerged jet pointing to the base of the tank can be influenced by the relaxation time of the liquid. We analyzed the temporal spreading of the boundary of a tracer‐front in two dimensions using flow visualization at early stages and found that for a given fluid, the evolution of the tracer‐front at various injection velocities follows a universal trajectory when considered on a normalized time scale of , where t is observation time, is injection velocity and is the effective diffusivity of the tracer elements in the medium. For a different fluid, at a given , the trajectory scales with the relaxation time of the fluid. The importance of relaxation time to the evolution of a tracer‐front is something previously unreported. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3132–3140, 2017 相似文献
19.
Let {X n :n∈N}be a linear process with bounded probability density function f(x). We study the estimation of the quadratic functional ∫ R f 2(x)dx. With a Fourier transform on the kernel function and the projection method, it is shown that, under certain mild conditions, the estimator has similar asymptotical properties as the i.i.d. case studied in Giné and Nickl 2008 if the linear process {X n :n∈N}has the defined short range dependence. We also provide an application to divergence and the extension to multi‐variate linear processes. The simulation study for linear processes with Gaussian and α‐stable innovations confirms our theoretical results. As an illustration, we estimate the divergences among the density functions of average annual river flows for four rivers and obtain promising results. 相似文献