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This study aimed to evaluate the optical properties of highly translucent 5 mol% yttria, partially stabilised monolithic zirconia, and 3 mol% yttria-stabilised tetragonal zirconia after their subjection to different milling methods and artificial ageing. Two types of pre-shaded zirconia materials were used: inCoris TZI C and Katana STML. A total of 120 specimens were categorised according to the milling method (dry or wet-milling) and the solution used for milling (fresh distilled water or impregnated water with residues of CAD/CAM ceramic materials). The translucency and contrast ratios of all specimens were calculated after they were subjected to sintering and accelerated ageing. The material phase composition was tested before and after ageing, using X-ray diffraction analysis to evaluate T-M phase transformation. Data were statistically analysed via a three-way analysis of variance between the subject factors, the material and milling method, and the within-subject factor, ageing. The analysis of covariance model was used to analyse the changes in translucency and contrast ratio between baseline and ageing, with statistical significance set at p < 0.05. Katana STML and inCoris TZI C showed the highest translucency when dry-milled (21.9 ± 1.4, and 11.8 ± 0.7, respectively), and the lowest when milled with used impregnated water (5.4 ± 1.2 and 10.7 ± 1.3, respectively). Wet-milling using impregnated water, should be avoided owing to the saturation of alumina particles. Accelerated ageing resulted in the same pattern for both materials. Significance Dry milling of highly translucent zirconia can result in higher translucency and lower contrast ratio values. [ABSTRACT FROM AUTHOR]

This paper makes a case for why Hawaii is the rainbow capital of the world. It begins by briefly touching on the cultural and historical significance of rainbows in Hawaii. Next it provides an overview of the science behind the rainbow phenomenon, which provides context for exploring the meteorology that helps explain the prevalence of Hawaiian rainbows. Last, the paper discusses the art and science of chasing rainbows. [ABSTRACT FROM AUTHOR]

We present algorithms for fast computation of phase functions of atmospheric clouds and for stochastic simulation of such optical phenomena as fogbows, glories, coronas and halos. Using the developed numerical algorithms and software, we analyze optical phenomena for several cloud and fog models. [ABSTRACT FROM AUTHOR]

High‐translucency restorative materials are commonly used in the restoration of anterior teeth where aesthetics is a critical factor. In this in vitro study, the impact of mouthwash on the colour stability and surface characteristics of high‐translucency computer‐aided design and computer‐aided manufacturing (CAD‐CAM) dental restorative materials was evaluated. Two‐hundred specimens were fabricated from five high‐translucency CAD‐CAM materials: a resin nano ceramic; a polymer‐infiltrated ceramic network; a feldspathic ceramic; a lithium disilicate glass ceramic; and high‐translucency zirconia. Each group of ceramic specimens was then divided into four subgroups: conventional mouthwash (LISTERINE); whitening mouthwash (LISTERINE Healthy White); chlorhexidine gluconate; and distilled water. Oral rinsing was simulated at 100 rpm for 180 h, representing 15 yr of clinical simulation. The specimens were then evaluated for colour, translucency, gloss, roughness, and surface morphology. Two‐way ANOVA and linear mixed models were used for intergroup comparisons (α = 0.05). The polymer‐infiltrated ceramic network and feldspathic ceramic became brighter, more opaque, less glossy, and rougher after rinsing with the whitening mouthwash. The long‐term use of specific mouthwashes can cause deterioration of the optical and surface properties of high‐translucency CAD‐CAM dental restorations. [ABSTRACT FROM AUTHOR]

Objective: The aim of this in vitro study was to evaluate the effects of substrate colors, different levels of ceramic thickness and translucency, and cement shades on the color difference from a reference color of lithium‐disilicate crowns. Materials and Methods: A premolar tooth preparation was made on a study model for 1.0 and 1.5 mm thick full‐ceramic crowns. Digital impressions were taken (3Shape TRIOS) and crowns designed in a CAD program (DentalDesigner). Shade A1 crowns were milled (Everest, Kavo) from high‐translucency (HT) and low‐translucency IPS e.max (Ivoclar Vivadent) blocks. Twelve substrates were made of different colors and materials (Natural Die Material, Co‐Cr, zirconia, and gold‐colored alloy). Three different shades of try‐in pastes were used to simulate the effect of cements (Variolink Esthetic try‐in paste; Ivoclar). Shade measurement was done three times for each crown by a spectrophotometer (VITA Easyshade Advance); averages were compared to a reference crown (A1, HT, 1.5 mm, ND2 abutment, neutral try‐in paste) with ΔE00 (CIEDE2000, according to the CIE latest standard) calculated. Results: All the examined parameters influenced the ΔE00 of the crowns. The weakest effect was exerted by the try‐in paste. Conclusions: All examined parameters influenced the final color of e.max CAD lithium‐disilicate ceramic crowns. Clinical Significance: Matching the shade of ceramic crowns to the natural tooth color is a great challenge in dentistry. To meet patients' increasing esthetical expectations, CAD/CAM methods are very popular for full‐ceramic crowns. However, several factors such as the shade of the abutment, luting cement color, ceramic thickness, and translucency may influence the final color. Our objective was to measure the optical effect of these factors on the final shade of CAD/CAM lithium‐disilicate ceramic crowns. [ABSTRACT FROM AUTHOR]

The article presents the experience in the extra-curricular activity of using information technologies and interdisciplinary links between the subjects of physics and astronomy, geography and economics and biology and health education in the lower secondary level as means of interactivity. [ABSTRACT FROM AUTHOR]

This work is motivated by previous studies of transatlantic transport of Saharan dust and the observed quasi-static nature of coarse mode aerosol with a volume median diameter (VMD) of approximately 3.5 μm. The authors examine coarse mode contributions from transpacific transport of dust to North American aerosol properties using a dataset collected at the high-elevation Storm Peak Laboratory (SPL) and the nearby Atmospheric Radiation Measurement (ARM) Mobile Facility. Collected ground-based data are complemented by quasi-global model simulations and satellite and ground-based observations. The authors identify a major dust event associated mostly with a transpacific plume (about 65% of near-surface aerosol mass) in which the coarse mode with moderate (~3 μm) VMD is distinct and contributes substantially to total aerosol volume (up to 70%) and scattering (up to 40%). The results demonstrate that the identified plume at the SPL site has a considerable fraction of supermicron particles (VMD ~3 μm) and, thus, suggest that these particles have a fairly invariant behavior despite transpacific transport. If confirmed in additional studies, this invariant behavior may simplify considerably parameterizations for size-dependent processes associated with dust transport and removal. [ABSTRACT FROM AUTHOR]

Koschmieder proposed that visibility is inversely proportional to the extinction coefficient of air, and this model has been widely adopted during the past century. Using radiative transfer theory, the authors present a general relationship for the law of contrast reduction and point out that the Koschmieder model is workable only to situations when a common-size object can be viewed tens of kilometers away. However, the Koschmieder model is not applicable for viewable distances of hundreds of meters when the angular dimension of an object is significantly greater than the eye resolution of the human being. The authors further separate the term 'visible' into 'simple detection' or 'detectability' and 'clear identification' or 'identifiability' and point out that the Koschmieder model is applicable to identifiability, but not necessarily for detectability. In addition, the way of calculating contrast is revised to follow the concept of brightness constancy. The results of this effort advocate the measurement and distribution of detectability in harsh weather conditions, as such data offer more useful and important information for daily life. [ABSTRACT FROM AUTHOR]

Experimental data on the extraordinary optical phenomena observed in our country and abroad during selected rocket launches are discussed. A particular interpretation of these data on the basis of common methodological and theoretical positions is presented. [ABSTRACT FROM AUTHOR]

The Airborne Remote Optical Spotlight System (AROSS) family of sensors consists of airborne imaging systems that provide passive, high-dynamic range, time series image data and has been used successfully to characterize currents and bathymetry of nearshore ocean, tidal flat, and riverine environments. AROSS-multispectral polarimeter (AROSS-MSP) is a 12-camera system that extends this time series capability to simultaneous color and polarization measurements for the full linear polarization of the imaged scene in red, green, and blue, and near-infrared (RGB-NIR) wavelength bands. Color and polarimetry provide unique information for retrieving dynamic environmental parameters over a larger area (square kilometers) than is possible with typical in situ measurements. This particular field of optical remote sensing is developing rapidly, and simultaneous color and polarimetric data are expected to enable the development of a number of additional important environmental data products, such as the improved ability to image the subsurface water column or maximizing wave contrast to improve oceanographic parameter retrievals of wave spectra and wave heights. One of the main obstacles to providing good-quality polarimetric image data from a multicamera system is the ability to accurately merge imagery from the cameras to a subpixel level. This study shows that the imagery from AROSS-MSP can be merged to an accuracy better than one-twentieth of a pixel, comparing two different automated algorithmic techniques. This paper describes the architecture of AROSS-MSP, the approach for providing simultaneous color and polarization imagery in space and time, an error analysis to characterize the measurements, and example color and polarization data products from ocean wave imagery. [ABSTRACT FROM AUTHOR]

A method for estimating multivariate functional relationships between sets of measured oceanographic, meteorological, and other field data is presented. Model II regression is well known for describing functional relationships between two variables. However, there is little accessible guidance for the researcher wishing to apply model II methods to a multivariate system consisting of three or more variables. This paper describes a straightforward method to extend model II regression to the case of three or more variables. The multiple model II procedure is applied to an analysis of the optical spectral scattering coefficient measured in the coastal ocean. The spectral scattering coefficient is regressed against both suspended mineral particle concentration and suspended organic particle concentration. The regression coefficients from this analysis provide adjusted estimates of the mineral particle scattering cross section and the organic particle scattering cross section. Greater accuracy and efficiency of the coefficients from this analysis, compared to semiempirical coefficients, is demonstrated. Examples of multivariate data are presented that have been analyzed by partitioning the variables into arbitrary bivariate models. However, in a true multivariate system with correlated predictors, such as a coupled biogeochemical cycle, these bivariate analyses yield incorrect coefficient estimates and may result in large unexplained variance. Employing instead a multivariate model II analysis can alleviate these problems and may be a better choice in these situations. [ABSTRACT FROM AUTHOR]

Abstract: Currently, photovoltaic (PV) electricity production models are based on thermal principles using constant optical coefficients (reflectance, transmittance and absorbance). However, these coefficients actually depend on the incident angle, and therefore, are a function of the inclination and orientation of PV panel as well as of the geographical position and time. In this paper we take into account the varying optical coefficients in the energy balance equations. Firstly, the incident angle of direct radiation is determined using simplified astronomic calculations and secondly the optical coefficients are calculated following the principles of classical electromagnetic theory. Finally, the energy balance equations are expressed as differential equations and are solved numerically by Runge–Kutta method to obtain the electrical power as a function of time. In order to validate the influence of optical phenomena, several use-cases (different geographical position, inclination, orientation) are considered and the results show significant differences regarding electricity production between our optical–thermal approach and classical thermal model. The difference is time-dependent and can reach up to 13.9% in some cases. [Copyright &y& Elsevier]

Gaspard Monge (1746-1818), creator of descriptive geometry and founder of the École Polytechnique, was one the main boosters of the awakening of higher mathematics that took place at the end of the 18th century. He played an important role in the French government during the Revolution and suffered the consequences after the fall of Napoleon. Among his many activities, he carried on important researches in Chemistry and Physics, particularly in the study of the synthesis and determination of the composition of water, iron metallurgy, capillarity, and the establishment of the meter as a unit of length. [ABSTRACT FROM AUTHOR]

In this article we argue that the views that Francis Bacon and René Descartes held about the role of experiments in the process of discovery are closer than previously accepted. Looking at the way experiments and the heuristics of experimentation are embedded in Bacon's posthumous History of Dense and Rare and Descartes' Discourses 8, 9, 10 of the Meteorology, we will show that experiments help the investigator both in solving specific problems that could not have otherwise been foreseen and in generating relevant information that advances the scope of the investigation. [ABSTRACT FROM AUTHOR]

This work deals with two kinds of contrails. The first comprises a large number of optically thin contrails near the tropopause. They are mapped geographically using a lidar to obtain their height and a camera to obtain azimuth and elevation. These high-resolution maps provide the local contrail geometry and the amount of optically clear atmosphere. The second kind is a single trail of unprecedentedly large optical thickness that occurs at a lower height. The latter was observed fortuitously when an aircraft moving along the wind direction passed over the lidar, thus providing measurements for more than 3 h and an equivalent distance of 620 km. It was also observed by Geostationary Operational Environmental Satellite (GOES) sensors. The lidar measured an optical depth of 2.3. The corresponding extinction coefficient of 0.023 km−1 and ice water content of 0.063 g m−3 are close to the maximum values found for midlatitude cirrus. The associated large radar reflectivity compares to that measured by ultrasensitive radar, thus providing support for the reality of the large optical depth. [ABSTRACT FROM AUTHOR]

Abstract: The CdSe nanoparticles have been prepared in the novel glass matrix P2O5–Na2O–ZnO–Li2O. The prepared nanoparticles and glass matrix are characterized by differential thermal analysis, X-rays diffraction, UV–vis optical absorption, and infrared spectroscopy. X-rays diffraction and optical absorption show that both of the annealing temperature and time play an important role in nanoparticles’ growth. The well-annealed and high-temperature-annealed samples suggest Zn atoms to substitute Cd atoms to form an additional ZnSe–CdSe system. Infrared spectroscopy confirms the decrease of the Zn-content in the host glass due to growing of nanoparticles, causing long phosphate chains within. [Copyright &y& Elsevier]

Abstract: We have prepared Cd1− x Zn x S quantum dots capped with bifunctional molecule mercaptoacetic acid. UV–vis absorption shows an increase of band gap as Zn substitutes Cd; the absorption band shifts from 331nm (x=0) to 295nm (x=1). We have calculated the size differences of CdS and ZnS quantum dots and correlate them to the electron density at sulfur atoms and ligand bond lengths of CdS and ZnS. Photoluminescence emission of CdS shows a sharp peak at 363nm and broad band at around 428nm, whereas ZnS shows the sharp peak at 331nm and a tail at around 415nm. The behavior of surface state emission with respect to band-edge emission for CdS and ZnS has been investigated and explained in terms of the surface per volume ratio of the two nanocrystals. The band-edge emission of CdS nanoparticles has been found to depend on the excitation energy. The trap state emission bands of CdS and ZnS and effect of excitation energy on the position of these bands have been studied. [Copyright &y& Elsevier]

Many attempts have been made to improve the translucency of zirconia in dentistry. The purpose of this study was to evaluate the effect of a rapid-cooling heat treatment on the optical and mechanical properties of dental monolithic zirconia. Zirconia containing 3, 4, and 5 mol% Y2O3 were sintered, sectioned, and polished. The specimens were rapidly cooled from high temperature inducing a diffusionless cubic-to-metastable tetragonal (t') phase transformation. The changes in L*a*b* color coordinates, translucency parameter (TP), and total transmittance (T%) were measured. Three-point bending strength, Vickers hardness, and indentation fracture toughness tests were performed. Quantitative phase analyses were carried out by X-ray diffraction with Rietveld refinement. Scanning electron microscopy (SEM) images were obtained. With increasing Y2O3 contents, TP and T% values increased while strength and toughness decreased. The Rietveld analysis showed that the amount of t'-phase increased after rapid-cooling and annealed 5Y-partially stabilized zirconia (PSZ) contained the highest amount of t'-phase (64.4 wt%). Rapid-cooling improved translucency but the translucency of annealed 5Y-PSZ did not approach that of lithium disilicate glass-ceramic. Rapid-cooling decreased flexural strength significantly, being 306.1 ± 61.8 MPa for annealed 5Y-PSZ. SEM revealed that grains tended to get larger after rapid-cooling. A rapid-cooling treatment can produce t'-phase which can contribute to an increase in translucency but has a negative effect on the mechanical properties of zirconia. [ABSTRACT FROM AUTHOR]