Translucent Materials Research Articles

Conventional and Advanced Glazing Technologies for Enhancing Thermal and Lighting Performance

Glass is one of the oldest man-made material that is widely used in architecture. As it is a translucent material, it permits a full penetration of direct sunlight but may also increase the internal space temperature and then increasing cooling loads and energy consumption. As the need for energy optimization is very important and glazing is considered a weak point in any building, the selection of glazing assumes tremendous significance. This paper reviews the different types of glazing which can be categorized into conventional and advanced to optimize the thermal and the lighting performance according to their properties and insulation values. Conventional glazing includes the clear glazing whether it is single double or triple, the tinted glazing, the reflective glazing, and the low-E glazing. Advanced glazing which is mainly the insulated glazing unit such as the gas filled glazing, the vacuum glazing, the aerogel glazing and the phase change material glazing.

Influence of yttria content and surface treatment on the strength of translucent zirconia materials

Statement of problemNewly developed translucent zirconia materials have been used for anterior monolithic complete coverage restorations. Surface treatments can improve adhesion, as well as decrease or increase the strength of ceramics. However, information on the influence of surface treatments on the strength of translucent zirconias is sparse. PurposeThe purpose of this in vitro study was to measure and characterize the effects of different surface treatments, including airborne-particle abrasion, on the strength of different translucent 4 mol% and 5 mol% yttria-stabilized zirconia materials. Materials and methodsDisks (N=160) made from 4 types of translucent yttria-stabilized zirconia materials were surface-treated in 4 ways: Control groups were hand-polished with 2000-grit silicon carbide abrasive paper; as-machined; glass bead airborne-particle abraded; and alumina airborne-particle abraded. The biaxial flexural strength was measured by using a piston-on-3-ball test in a universal testing machine. The simple main effects of material type and surface treatment and their interaction on biaxial flexural strength were evaluated with 2-way ANOVA (α=.05). A priori, 1-way ANOVA and the Tukey multiple comparisons tests were used within material and treatment types (α=.05). Surface morphology was assessed by using scanning electron microscopy. Translucency, absolute transmittance, was measured by using a spectrophotometer. ResultsTwo-way ANOVA revealed that the effects of zirconia type, surface treatment, and their interaction all significantly affected biaxial flexural strength (P<.001). One-way ANOVA revealed that the 4Y material was stronger than all 5Y materials, regardless of surface treatment; all 5Y materials were ranked from strongest to weakest as polished; as-machined, or glass bead abraded; and alumina abraded. The 4Y material was stronger when alumina abraded than when glass bead abraded. Scanning electron microscopy showed that as-polished surfaces were smoother than all others; as-machined and glass bead abraded surfaces displayed little difference; alumina abraded was the roughest; and differences among materials were not discerned. The 1-way ANOVA and multiple comparisons testing showed that the 4Y material had less absolute transmittance, approximately 5% less, than all the 5Y materials. ConclusionsZirconia material type and surface treatment influenced the strength of translucent zirconia materials; a 4 mol% zirconia material was stronger than 5 mol% zirconia materials for all surface treatments tested; airborne-particle abrasion using alumina had a slight strengthening effect on a 4 mol% zirconia but had a weakening effect on 5 mol% materials; airborne-particle abrasion by using alumina produced the roughest surfaces on all materials; and the 4 mol% material was slightly less translucent than the 5 mol% materials.

Parametric study of solid-solid translucent phase change materials in building windows

Thermal energy storage and solar radiation management are crucial to improve the sustainability and energy efficiency of buildings. Compared with the implementation of phase change materials (PCMs) in opaque components, the energy saving potential of incorporating PCMs in transparent glazing windows is much less studied and not well understood. Here we present a comprehensive parametric study of novel PCM windows for building energy saving with a focus on optimizing and quantitatively distinguishing the contributions from the optical and thermal properties of the PCM, which is particularly useful for the design of solid-solid PCM windows. We investigate a reference commercial office building using EnergyPlus by developing an equivalent model of our PCM window that is compatible with EnergyPlus’s modeling capabilities. Compared with a clear-clear double-pane window, the integration of 3 mm solid-solid PCMs with optimal properties in warm, mixed, and cold climates can respectively save up to 17.2%, 14.0%, and 5.8% energy for the HVAC (heating, ventilation, and air conditioning) system, and 9.4%, 6.7%, and 3.2% energy for the whole building. We also demonstrate that these energy savings are most sensitive to the solar absorptance of PCMs for all three climates. The optimal transition temperature varies with climate and is related to the climate and solar radiation heat gain. Other issues are also briefly discussed, such as hysteresis, window orientations, and the effect of interior lighting. Although the optimal PCM windows show energy saving performance comparable with low-emissivity windows, the PCM windows provide a unique advantage in terms of shifting HVAC loads which can provide benefits to the electrical grid.

Translucency and flexural strength of translucent zirconia ceramics

Statement of problemTranslucent zirconias have been developed with better esthetics than high-strength zirconias by reducing opacity. However, studies on their translucency and strength are sparse. PurposeThe purpose of this in vitro study was to compare the relationship between translucency and biaxial flexural strength of recently developed high-translucency zirconia, high-strength zirconia, and lithium disilicate ceramics. Material and methodsDisks (n=12) were fabricated for 5 ceramic materials: high-strength zirconia (BruxZir 16 shaded), translucent zirconia (BruxZir Anterior shaded, Katana UTML, Katana STML), and lithium disilicate (IPS e.max, Press HT, and LT). A standard tessellation language (STL) file was designed, and the specimen milled, finished, and glazed according to manufacturer's instructions for each material. The translucency parameter was calculated against black and white backgrounds and white and stump shade with ND4 background by using a spectrophotometer. Biaxial flexural strength was calculated by using the 3-ball test. The load was applied at a crosshead speed of 0.5 mm/min with a 49-N load cell until failure occurred. Translucency parameter and biaxial flexural strength data were analyzed with 1-way analysis of variance (ANOVA). A Tukey honest significant difference multiple comparison test was used to determine significant differences (α=.05). ResultsThe IPS e.max HT was more translucent against both backgrounds (32.85 for black/white and 15.34 for white/stump), while BruxZir 16 was the least translucent (19.78 for B/W and 8.83 for W/S). All groups tested differed in translucency (P<.001) except for BruxZir Anterior and Katana STML, which were not significantly different (P=.052). For biaxial flexural strength, BruxZir 16 had the highest strength (995.44 MPa) and e.max HT, the lowest (186.75 MPa). No significant differences were found between BruxZir anterior and Katana STML, Katana UTML and IPS e.max LT, or IPS e.max LT and IPS e.max HT (P>.05). Translucency parameter values using both backgrounds were strongly correlated (r=0.99). However, biaxial flexural strength values were inversely related to translucency parameter values when using black/white and white/stump shade but with high correlation (r=-0.777 and -0.756 respectively). ConclusionsLithium disilicate was the most translucent and yet the weakest material, whereas high-strength zirconia was the most opaque ceramic and the strongest. Katana UTML had the highest translucency but was weakest among translucent and high-strength zirconia materials. Overall, translucency was negatively correlated with biaxial flexural strength.

Porosity Centrifuge: Determination of Pore Sizes of Swellable Porous Materials under Hypergravity.

Porous materials are ubiquitous and essential for many processes in nature as well as in industry, and the need to produce them from renewable materials will definitely increase. A prominent example for such a fully recyclable and biogenic porous material is paper, a material that contains macropores formed in between the fibers as well as a large distribution of much finer pores on and within the fiber walls. While the determination of pore sizes is of central importance for the characterization of such materials, their determination is usually only possible with complex methodologies. The determination of pore sizes in the context of water has remained largely unsolved to date, in particular, if water-swellable materials are considered. Here, we introduce a completely new way of determining pore sizes of materials even under swelling conditions. Using a centrifugal device and studying the imbibition of water into paper at various centrifugal forces that oppose the capillary forces, we can access the mean pore size of different paper materials in an experimentally simple fashion. In addition, we can show that the pore size values obtained with our "centrifugal porosimetry" are consistent with the values obtained using other methods, usually much more involved methods. For this purpose, we measure well-characterized translucent macroporous materials using water, ranging from simple glass capillaries to standard filters and nitrocellulose membranes.

Synthesis, characterization and application of gelatine and dithiocarbamylated chitin

Introduction: Gelatin or gelatine is a translucent, colorless, flavorless, and biodegradable material obtained from collagen present in animal body parts, such as skin, bones, and connective tissues of animals, e.g., domestic cattle, chicken, pigs, and fish. It is a mixture of peptides and proteins obtained by acid and alkaline processing of collagen and is commonly used as a gelling agent in food, pharmaceuticals, photographic films and papers, and cosmetics. Dithiocarbamates (DTC) are well known adsorbents (1-2). We reported preparation and characterization of dithiocarbamylated chitin (CHDTC) in a previous communication (3). CHDTC was found to possess good adsorption capacity, but recovery of adsorbent was not convenient. Therefore, it was envisaged to blend CHDTC with gelatine to not only enhance adsorption capacity but enable reuse of adsorbent also. Methods: Gelatine was blended with CHDTC and polyvinyl alcohol (PVA) to prepare an asymmetric membrane (AMCG), which was characterized by FTIR spectral analysis, powder X-ray diffraction measurements and scanning electron microscopy. Results & Discussion: Adsorption of crystal violet dye from its aqueous solution in 5 to 30 mg/L concentration range by AMCG was investigated using ultraviolet spectrophotometric measurements. Adsorption isotherm study indicated that Langmuir equation fitted better than the Freundlich, Temkin and Dubinin-Radushkevich equations, indicating adsorption process mainly to be monolayer. Adsorption kinetics studies suggested pseudo second order kinetics. AMCG was found to be very efficient adsorbent and maximum adsorption capacity was found to be 500 mg/g for crystal violet. Adsorption was studied at pH 4, 7 and 9. Adsorption was most rapid at pH 9 and almost 95% of crystal violet was observed within 1 h. Further, four adsorption/desorption cycles were followed, which clearly indicated AMCG to be a potential adsorbent for recycling of water from industrial effluents. Conclusions: AMCG is a suitable adsorbent for recycling of wastewater especially from industrial effluents. It shows high adsorbent capacity and fast removal of crystal violet as a model pollutant. Monolayer adsorption process enables recycling of adsorbent and recovery of the valuable compounds/ materials from effluents. Keywords: Recycling of water, Gelatine, Dithiocarbamylated chitin, Dye adsorption. Acknowledgment: Authors are thankful to Central Instrumentation Facility Laboratory, Govt. Science College, Jabalpur for XRD and FTIR spectral analysis.

Implant Restorative Options in the Esthetic Zone: Anodized Versus Zirconia Abutments.

Restoring implants in the esthetic zone can be regarded as one of the more difficult procedures in dentistry. The use of customized abutments has become a common practice to aid in the development of a proper emergence profile of restorations. The standard material over the years has been titanium, however, the emergence of zirconia as a restorative option has become popular when restoring with more translucent materials like lithium disilicate. A compromise between strength and esthetics is anodizing the titanium abutments to have a yellow color to help mask the grey hues from the silver abutments. This case report aims to provide readers with information comparing anodized and zirconia abutments when restoring implants with lithium disilicate restorations in the esthetic zone.

Optical properties evaluation of rapid sintered translucent zirconia with two dental colorimeters

Background/purposeThe efficient rapid sintering technique has employed to dental zirconia ceramics for shortening the fabrication time of zirconia restorations. The purpose was to compare the optical properties of two generations of rapid sintered translucent zirconia using two dental colorimeters. Materials and methodsTwo generations of translucent zirconia ceramics, 3 mol% yttria-tetragonal zirconia polycrystal (3Y-TZP): Copran Zr-i Ultra-T (UT) and Cercon HT (HT), and 5 mol% yttria-tetragonal zirconia polycrystal (5Y-TZP): Cercon xt (XT), of different thicknesses (0.5, 0.8, and 1.2 mm; n = 5) underwent rapid sintering (RS) or conventional sintering (CS). The CIELAB values were measured on the white and black backgrounds, respectively, by digital colorimeters, shadepilot, DeguDent (DD) and Easyshade V, Vita (Vita). Translucency parameter (TP), color difference (ΔE), surface morphology, and surface roughness were evaluated. ResultsRS resulted in reduced lightness, except in the XT group. The chromaticity increased slightly after RS. Translucency decreased with increasing material thickness. ΔE values differed between both sintering processes but were clinically acceptable (ΔE < 5). Grain size of XT decreased after RS. RS did not affect the surface roughness. ConclusionRS is a feasible method for shortening the manufacturing time of zirconia restorations. A significant difference in TP value was only in the XT group between both sintering methods as measured on DD. Color differences in rapid sintered translucent zirconia materials are imperceptible and acceptable. The specimen thickness affected more in the TP values of Vita than DD. DD has higher sensitivity to translucency and color compared with Vita.

Learning Multiple‐Scattering Solutions for Sphere‐Tracing of Volumetric Subsurface Effects

AbstractAccurate subsurface scattering solutions require the integration of optical material properties along many complicated light paths. We present a method that learns a simple geometric approximation of random paths in a homogeneous volume with translucent material. The generated representation allows determining the absorption along the path as well as a direct lighting contribution, which is representative of all scatter events along the path. A sequence of conditional variational auto‐encoders (CVAEs) is trained to model the statistical distribution of the photon paths inside a spherical region in the presence of multiple scattering events. A first CVAE learns how to sample the number of scatter events, occurring on a ray path inside the sphere, which effectively determines the probability of this ray to be absorbed. Conditioned on this, a second model predicts the exit position and direction of the light particle. Finally, a third model generates a representative sample of photon position and direction along the path, which is used to approximate the contribution of direct illumination due to in‐scattering. To accelerate the tracing of the light path through the volumetric medium toward the solid boundary, we employ a sphere‐tracing strategy that considers the light absorption and can perform a statistically accurate next‐event estimation. We demonstrate efficient learning using shallow networks of only three layers and no more than 16 nodes. In combination with a GPU shader that evaluates the CVAEs’ predictions, performance gains can be demonstrated for a variety of different scenarios. We analyze the approximation error that is introduced by the data‐driven scattering simulation and shed light on the major sources of error.

Mechanical properties of translucent cement under the action of sodium sulfate and magnesium sulfate

This study is a study of Mechanical properties of translucent cement under the action of sodium sulfate and magnesium sulfate. The objectives of the study are: 1. to find the appropriate ratio to obtain a cement substitute for high compressive strength welding. The ratio of epoxy resin (translucent material) can be obtained at the lowest cost. 2. To study the influence of the electric oven energy curing condition on the compressive strength properties and physical properties corrosion resistance, both acid and base. 3. To study the feasibility of capping gypsum and resin that qualifies for construction work. From the property analysis and to estimate the duration of using capping gypsum and epoxy resin (Translucent material) cured by electric oven and room temperature conditions, it was found that the optimal ratio for obtaining the highest compressive strength cement replacement material was the by-weight ratio of epoxy resin of substance A and substance B is 100/60, baked at 80 degrees, soaked in water for 56 days to obtain a cement substitute for high compressive strength welding. The amount of water to be used mixed with high strength gypsum powder was 21%, duration 7 days, baked at 90 degrees and soaked in air. When considering the angle of use in construction instead of concrete, it was found that the most common ready-mixed concrete in the design of compressive strength ranging from 180-400 ksc and the most commonly used is 240 ksc cylinder. Therefore, when considered and found that Translucent cement under the action of sodium sulfate and magnesium sulfate. The compressive strength is between 200-800 ksc. General concrete work is mainly tested for the compressive strength. This is used to control the quality of work and can also be used as an indicator of other aspects as well. This is because the resistance to other forces is directly proportional to the compressive strength.

Impact of varying step-stress protocols on the fatigue behavior of 3Y-TZP, 4Y-TZP and 5Y-TZP ceramic

ObjectiveTo test the impact of three varying step-stress protocols on the fatigue behavior of two 3Y-TZP, one 4Y-TZP and one 5Y-TZP zirconia materials. MethodsEight specimens per zirconia material (N = 32) were selected for static testing to determine the start load for dynamic tests (30% of the mean value of static fracture load). 45 specimens per material (N = 180) were used for dynamic load tests using three step-stress protocols: 1. 50 N/5000 cycles; 2. 5% of static load/5000 cycles, and 3. 10 N/1000 cycles. Following materials were tested: 3Y-TZP(<0.25 Al2O3) (O: opaque) 3Y-TZP(<0.05 Al2O3) (T: translucent), 4Y-TZP(<0.01 Al2O3) (ET: extra translucent) and 5Y-TZP(<0.01 Al2O3) (HT: high translucent). The specimens (4 ± 0.02 × 3 ± 0.02 × 45 mm) were placed centrally on the support rolls and the load was applied perpendicularly over the 4 mm specimen side (∼4-point flexural strength according to the DIN 6872:2019). Data was analyzed with Kolmogorov–Smirnov-test, t-test, one-way ANOVA with post-hoc Scheffé-test, Chi-square-test, Kaplan–Meier with Log-Rank-test and two-parametric Weibull analysis (p < 0.05). ResultsThe step-stress protocols showed no impact on the fracture load or Weibull modulus within one zirconia material. However, the zirconia materials T, ET and HT showed differences in cycle number to fracture between the step-stress protocols (T: 3 > 2 > 1; ET: 2 > 3 > 1; HT: 2, 3 > 1) with lowest cycle number to fracture for protocol 1. Within one step-stress protocol, the cycle number to fracture varied according to the zirconia material as follows: 1: T, O ≥ O, ET > HT; 2: ET > O, T, HT; 3: O, T, ET > HT. Cracking started at the tensile side of the specimens at all times. All specimens showed typical compression curls (single or double). Fragmentation patterns were similar for all materials with a lot of crack branching and fragmentation due to secondary cracks indicating high energy fractures. SignificanceDynamic fatigue tests seem to provide important information on the long-term stability of zirconia materials. Zirconia materials with higher opacity seem to be more robust towards varying step-stress protocols than translucent zirconia materials. Regarding expenditure of time, a step-stress protocol with a load increase of 50 N every 5000 cycles seems favorable to gain information on the long-term stability of zirconia materials.

Obtaining plasticized starch and microfibrillated cellulose from oil palm empty fruit bunches: Preparation and properties of the pure materials and their composites

Starch and celluloses are biodegradable resources of great importance in terms of marketing. These biopolymers can be used to generate films with interesting mechanical, optical, and thermal properties, which can substitute for plastic films in certain applications, e.g., packaging materials. This study describes the preparation of pure plasticized starch films, prepared from soluble starch and glycerol, and the preparation of microfibrillated cellulose films from oil palm empty fruit bunches fabricated via casting. Composites made of plasticized starch were also prepared with microfibrillated cellulose added in 10% increments. The density, color difference, opacity, morphology, water activity, water affinity, and thermal and mechanical characteristics of the films were investigated. Plasticized starch is a translucent material with contact transparency; it is fragile and has relatively high water and glycerol contents. The thermogravimetric analysis of materials displayed up to four stages of weight loss related to water evaporation, glycerol, starch, and cellulose thermal degradation. As a consequence, the materials with higher cellulose content exhibited better thermal resistance. The composites with 90% of microfibrillated cellulose resulted in increased tensile strength when compared to the pure materials. The pure microfibrillated cellulose presented the highest values of Young modulus. The addition of plasticized starch to microfibrillated cellulose improved the maximum strain of the composites.

The cospecification of the shape and material properties of light permeable materials

The problem of extracting the three-dimensional (3D) shape and material properties of surfaces from images is considered to be inherently ill posed. It is thought that a priori knowledge about either 3D shape is needed to infer material properties, or knowledge about material properties are needed to derive 3D shape. Here, we show that there is information in images that cospecify both the material composition and 3D shape of light permeable (translucent) materials. Specifically, we show that the intensity gradients generated by subsurface scattering, the shape of self-occluding contours, and the distribution of specular reflections covary in systematic ways that are diagnostic of both the surface's 3D shape and its material properties. These sources of image covariation emerge from being causally linked to a common environmental source: 3D surface curvature. We show that these sources of covariation take the form of "photogeometric constraints," which link variations in intensity (photometric constraints) to the sign and direction of 3D surface curvature (geometric constraints). We experimentally demonstrate that this covariation generates emergent cues that the visual system exploits to derive the 3D shape and material properties of translucent surfaces and demonstrate the potency of these cues by constructing counterfeit images that evoke vivid percepts of 3D shape and translucency. The concepts of covariation and cospecification articulated herein suggest a principled conceptual path forward for identifying emergent cues that can be used to solve problems in vision that have historically been assumed to be ill posed.

Ballistic performance of Polycarbonate and Polymethyl methacrylate under normal and inclined dynamic impacts

Polymeric materials have exceptional mechanical properties, making them attractive for automotive, aerospace, defence and buildings industries. The numerical analysis of translucent polymeric materials' ballistic performance is investigated to analyse the deflection and perforation performance at high impact velocities. Computational methods are exploited to predict the ballistic performance of thick targets and projectile damage, and the results are validated against published works. The 3D numerical analysis is conducted by simulating plates and projectiles' mechanical performance that controls the deflection and ricochet procedure. Impact damage analysis is undertaken on monolithic Polycarbonate (PC) and Polymethyl methacrylate (PMMA) targets under various impact velocities, projectile's core density with inclined 30∘ and normal 90∘ impact angle. The results are analysed in terms of failure performance, depth of penetration (DOP), penetration path (POP), and residual velocity. The numerical analysis is further developed to investigate the projectile's impact velocity effects on the DOP and its direction. The results showed that the DOP changes linearly with the impact velocity, where the POP is as yet nonlinear. Extended Drucker Prager Strength (EDP) material model with the failure criteria of principal stress and tensile pressure failure is used to simulate the brittle-ductile PMMA target's performance under dynamic impact. Shock Hugoniots equation of state with plastic strain failure is conducted to affect PC plates' tensile performance.

Influence of different material substrates on the accuracy of 3 intraoral scanners: A single-blinded in vitro study.

To compare the accuracy of three commercially available intraoral scanners when imaging various dental material substrates.A maxillary dentate typodont model with 11 different dental material substrates was prepared and scanned using three intraoral scanners (TRIOS 3, 3Shape; CS 3600, Carestream; and Emerald S, Planmeca). The model was further scanned with a laboratory scanner (7series, Dental Wings) for reference. Files were exported in standard tessellation language format and inserted into a metrology 3D mesh software (CloudCompare).In terms of influence of different substrates on IOS trueness, a significant effect on the performance of TRIOS 3 and Emerald S was revealed. Concerning the accuracy of different intraoral scanners when scanning more translucent and reflective materials, pairwise comparisons revealed significant differences among scanners. In terms of complete-arch trueness and precision, pairwise comparisons revealed that TRIOS 3 had significantly higher trueness and precision compared to CS3600 and Emerald S. The complete-arch trueness and precision of CS3600 and Emerald S did not differ significantly.Dental material substrates influenced the accuracy of all three tested scanners. The full metal crown exhibited significantly lower trueness compared to other substrates across all three scanners. For the high-translucency substrate group, TRIOS 3 exhibited significantly higher trueness compared to CS 3600. Polished and unpolished class II amalgam restorations of similar dimensions did not exhibit significant differences in trueness regardless of intraoral scanner. In terms of complete-arch accuracy, TRIOS 3 had significantly higher trueness and precision compared to CS 3600 and Emerald S. All three scanners exhibited complete-arch average accuracy below 100 μm.

Influence of Different Material Substrates on the Accuracy of Three Intraoral Scanners: A Single-Blinded In Vitro Study

George Michelinakis, DDS, MSc, MPhil/Dimitrios Apostolakis, DDS, MSc, MSc/Andreas Tsagarakis, DDS/Panagiotis Lampropoulos, DDS, Dr Med Dent: Purpose: To compare the accuracy of three commercially available intraoral scanners for the imaging of various dental material substrates. Materials and Methods: A maxillary dentate typodont model with 11 different dental material substrates was prepared and scanned using three intraoral scanners (Trios 3, 3Shape; CS 3600, Carestream; and Emerald S, Planmeca). The model was also scanned with a laboratory scanner (7series, Dental Wings) for reference. Files were exported in standard tessellation language (STL) format and inserted into a metrology 3D mesh software (CloudCompare). Results: In terms of the influence of different substrates on intraoral scanner trueness, a significant effect on the performance of Trios 3 and Emerald S was found. Pairwise comparisons revealed significant differences among scanners concerning accuracy when scanning more translucent and reflective materials. In terms of complete-arch trueness and precision, pairwise comparisons revealed that the Trios 3 had significantly higher trueness and precision compared to both the CS 3600 and Emerald S, but the complete-arch trueness and precision of the CS 3600 and Emerald S did not differ significantly. Conclusions: Dental material substrates influenced the accuracy of all three tested scanners. The full-metal crown exhibited significantly lower trueness compared to other substrates across all three scanners. For the high-translucency substrate group, the Trios 3 exhibited significantly higher trueness compared to the CS 3600. Polished and unpolished Class II amalgam restorations of similar dimensions did not exhibit significant differences in trueness regardless of intraoral scanner. In terms of complete-arch accuracy, the Trios 3 had significantly higher trueness and precision compared to both the CS 3600 and Emerald S. All three scanners exhibited a mean complete-arch accuracy below 100 μm.

Adaptive Irradiance Sampling for Many-Light Rendering of Subsurface Scattering.

Rendering a translucent material involves integrating the product of the transmittance-weighted irradiance and the BSSRDF over the surface of it. In previous methods, this spatial integral was computed by creating a dense distribution of discrete points over the surface or by importance-sampling based on the BSSRDF. Both of these approaches necessitate specifying the number of samples, which affects both the quality and the computation time for rendering. An insufficient number of samples leads to noise and artifacts in the rendered image and an excessive number results in a prohibitively long rendering time. In this article, we propose an error estimation method for translucent materials in a many-light rendering framework. Our adaptive sampling can automatically determine the number of samples so that the estimated relative error of each pixel intensity is less than a user-specified threshold. We also propose an efficient method to generate the sampling points that make large contributions to the pixel intensity taking into account the BSSRDF. This enables us to use a simple uniform sampling, instead of costly importance sampling based on the BSSRDF. The experimental results show that our method can accurately estimate the error. In addition, in comparison with the previous methods, our sampling method achieves better estimation accuracy in equal-time.

Color compatibility between dental structures and three different types of ceramic systems

BackgroundTo assess color compatibility between dental structures (human enamel and dentine) and three different types of ceramic systems.MethodsSamples (1 and 2 mm-thick) of extracted tooth (containing dentine and enamel areas) and three ceramic systems with different shades and opacities (HT–High Translucent, T–Translucent) were prepared for this study: Vita Suprinity—VS (HT, T; A1, A2, A3, A3.5, B2, C2, D2) (Vita Zahnfabrik); Vita Enamic—VE (HT, T; 1M1, 1M2, 2M2, 3M2) (Vita Zahnfabrik) and Noritake Super Porcelain EX-3—NKT (A1, A2, A3, A3.5, B2, C2, D2) (Kuraray Noritake Dental). Reflectance measurements of all samples were performed over black backgrounds using a non-contact spectroradiometer (SpectraScan PR-670, Photo Research) under a CIE 45°/0° geometry. CIE L*a*b* color parameters were measured and CIELAB/CIEDE2000 color differences (ΔE00/ΔE*ab) and corresponding Coverage Error (CE) of ceramic system for dentine or enamel samples were calculated. Color data was analyzed using one-way ANOVA and post-hoc multiple comparisons tests. CE values were interpreted by comparisons with available 50:50% acceptability color threshold (AT) for dentistry.ResultsStatistically significant differences in lightness were found among all ceramic systems and human dentine (p < 0.001), while no significant differences were registered between enamel and VSHT, T and VEHT. 1 mm dentine showed no statistical differences with VST and VSHT for a* coordinate, while 2 mm dentine showed no significant differences (p > 0.05) with VEHT. Thin samples (1 mm) of dentine and enamel showed significant statistical differences (p < 0.05) for b* coordinate with less translucent materials (NKT, VET and VST). For dentine samples, none of the ceramic materials provided a CE lower than AT. VSHT provided the best CE for 1 mm-thick (CE00 = 1.7, CEab = 1.9) and for 2 mm-thick (CE00 = 2.3; CEab = 2.5) enamel samples.ConclusionsColor coordinates of evaluated esthetic ceramic systems were statistically different from those of human dentine in almost all cases. The evaluated ZrO2 lithium silicate glass–ceramic (VS), with its two levels of translucency, provided lower CE values with human enamel samples while conventional feldspathic ceramic (NKT) and hybrid ceramic systems (VE) demonstrated a better color compatibility with dentin samples.

Optical and thermal properties of commercial polymer film, modeling the albedo effect

AbstractGreenhouse cladding materials are an important part of greenhouse design. The cladding material controls the light transmission and distribution over the plants within the greenhouse, thereby exerting a major influence on the overall yield. Greenhouse claddings are typically translucent materials offering more diffusive transmission than reflection; however, the reflective properties of the films offer a potential route to increasing the surface albedo of the local environment. We model thermal properties by modeling the films based on their optical transmissions and reflections. We can use this data to estimate their albedo and determine the amount of short wave radiation that will be transmitted/reflected/blocked by the materials and how it can influence the local environment.

Bayesian analysis of depth resolved OCT attenuation coefficients

Optical coherence tomography (OCT) is an optical technique which allows for volumetric visualization of the internal structures of translucent materials. Additional information can be gained by measuring the rate of signal attenuation in depth. Techniques have been developed to estimate the rate of attenuation on a voxel by voxel basis. This depth resolved attenuation analysis gives insight into tissue structure and organization in a spatially resolved way. However, the presence of speckle in the OCT measurement causes the attenuation coefficient image to contain unrealistic fluctuations and makes the reliability of these images at the voxel level poor. While the distribution of speckle in OCT images has appeared in literature, the resulting voxelwise corruption of the attenuation analysis has not. In this work, the estimated depth resolved attenuation coefficient from OCT data with speckle is shown to be approximately exponentially distributed. After this, a prior distribution for the depth resolved attenuation coefficient is derived for a simple system using statistical mechanics. Finally, given a set of depth resolved estimates which were made from OCT data in the presence of speckle, a posterior probability distribution for the true voxelwise attenuation coefficient is derived and a Bayesian voxelwise estimator for the coefficient is given. These results are demonstrated in simulation and validated experimentally.