The Locating Chromatic Number of Book Graph

Let G = V G , E G be a connected graph and c : V G ⟶ 1,2 , … , k be a proper k -coloring of G . Let Π be a partition of vertices of G induced by the coloring c . We define the color code c Π v of a vertex v ∈ V G as an ordered k -tuple that contains the distance between each partition to the vertex v . If distinct vertices have distinct color code, then c is called a locating k -coloring of G . The locating chromatic number of G is the smallest k such that G has a locating k -coloring. In this paper, we determine the locating chromatic number of book graph.

Improvement of double-layer phosphor structure WLEDS in color homogeneity and luminous flux

The concept of the analysis is to put a CaAl2O4:Mn2+ green phosphor layer on top of the YAG:Ce3+ yellow phosphor layer. After that, find the added CaAl2O4:Mn2+ concentration appropriate for the highest luminous flux (LF) and color homogeneity (CH). In this analysis, five equivalent WLEDs were applied but with distinct color temperatures, including 5600 K - 8500 K. The findings showed that CaAl2O4:Mn2+ brings great benefits to increase not only the luminous flux but also the color homogeneity. Especially, the higher the CaAl2O4:Mn2+ concentration, the more the luminous flux released by WLEDs, owing to the risen content of the light of green in WLEDs. Nevertheless, as the CaAl2O4:Mn2+ concentration raised significantly, a small reduction in the color rendering metric (CRI) and color quality scale (CQS) occurred. This is supported by simulation and calculation according to the theory of Monte Carlo. The paper results are the crucial contribution to the manufacture of WLEDs with better optical performance and color homogeneity of remote phosphor configurations.

Naphthyridine derived colorimetric and fluorescent turn off sensors for Ni2+ in aqueous media

Highly selective and sensitive 2,7-naphthyridine based colorimetric and fluorescence “Turn Off” chemosensors (L1-L4) for detection of Ni2+ in aqueous media are reported. The receptors (L1-L4) showed a distinct color change from yellow to red by addition of Ni2+ with spectral changes in bands at 535–550 nm. The changes are reversible and pH independent. The detection limits for Ni2+ by (L1-L4) are in the range of 0.2–0.5 µM by UV–Visible data and 0.040–0.47 µM by fluorescence data, which is lower than the permissible value of Ni2+ (1.2 µM) in drinking water defined by EPA. The binding stoichiometries of L1-L4 for Ni2+ were found to be 2:1 through Job’s plot and ESI–MS analysis. Moreover the receptors can be used to quantify Ni2+ in real water samples. Formation of test strips by the dip-stick method increases the practical applicability of the Ni2+ test for “in-the-field” measurements. DFT calculations and AIM analyses supported the experimentally determined 2:1 stoichiometries of complexation. TD-DFT calculations were performed which showed slightly decreased FMO energy gaps due to ligand–metal charge transfer (LMCT).

Optical Nature of Non-Substituted Triphenylmethyl Cation: Crystalline State Emission, Thermochromism, and Phosphorescence

Since the discovery of the triphenylmethyl (trityl) cation 120 years ago, a variety of aromatic cations having various colors and luminescence properties have been rigorously studied. Many, differently substituted trityl cations have been synthesized and their optical properties have been elucidated. However, the optical properties of the parent, non-substituted and highly reactive trityl cation, which was observed to be very weakly luminescent, have not been subjected to detailed investigation. In the effort described herein, we explored the optical nature of non-substituted trityl hexafluorophosphate (PF6) in the crystalline state. Trityl PF6 was found to exist as two crystal polymorphs including a yellow (Y) and an orange (O) form. Moreover, we observed that these crystalline forms display crystalline-state emission with different colors. The results of X-ray crystallographic analysis showed that the two polymorphs have totally different molecular packing arrangements. Furthermore, an investigation of their optical properties revealed that the O-crystal undergoes a distinct color change to yellow upon cooling as a consequence of a change in the nature of the charge transfer interaction between the cation and PF6 anion, and that both the Y and O crystal exhibit phosphorescence.

Binocular summation is affected by crowding and tagging

In perceptual crowding, a letter easily recognized on its own, becomes unrecognizable if it is surrounded by other letters, an effect that confers a limit on the visual processing. Models assume that crowding is a hallmark of the periphery but that it is almost absent in the fovea. However, recently it was shown that crowding occurs in the fovea of people with an abnormal development of functional vision (amblyopia), when the stimulus is presented for a very short time. When targets and flankers are dissimilar, the crowding is reduced (tagging). Since a combination of binocular inputs increases the processing load, we investigated whether color tagging the target reduces crowding in the fovea of subjects with normal vision and determined how crowding is combined with binocular vision. The crowding effect at the fovea was significantly reduced by tagging with a color target. Interestingly, whereas binocular summation for a single letter was expected to be about 40%, it was significantly reduced and almost absent under crowding conditions. Our results are consistent with the notion that the crowding effect produces a high processing load on visual processing, which interferes with other processes such as binocular summation. We assume that the tagging effect in our experiment improved the subject's abilities (sensitivity and RT) by creating a "segmentation", i.e., a visual simulated separation between the target letter and the background. Interestingly, tagging the target with a distinct color can eliminate or reduce the crowding effect and consequently, binocular summation recovers.

Color and Translucency Stability of Three-Dimensional Printable Dental Materials for Crown and Bridge Restorations

The purpose of this study was to examine and compare color and translucency stability of three-dimensional (3D) printable dental materials for crown and bridge restorations. Five different materials were investigated, and twelve disc-shaped specimens of two different thicknesses (1 and 2 mm) were prepared using a digital light processing 3D printer. Color measurements were made according to the CIELAB color scale (L*, a*, and b*) using a spectrophotometer 1 h, 1 day, 1 week, one month, and six months after post-curing of the materials, and the translucency parameter (TP) was calculated. The L*, a*, b*, and TP values were compared among the different materials and storage periods using repeated measures analysis of variance. Color and translucency changes of the specimens after the different storage periods were compared with 1 h measurements to determine whether they exceeded clinically perceivable thresholds. The L*, a*, b*, and TP values showed significant differences according to the storage periods, as well as among the materials. Until one month, some materials demonstrated distinct color differences, while others showed small color differences below a clinically perceivable threshold. The translucency differences were not clinically perceivable for any specimen. After six months, all specimens demonstrated large color changes, whereas the changes in translucency were relatively small. In conclusion, the color of 3D printable dental materials changed with time, and the differences varied with the materials used. On the contrary, the changes in translucency were small. Overall, the materials became darker, more yellowish, and more opaque after six months of water storage.

Anion Binding Studies of Urea and Thiourea Functionalized Molecular Clefts

Two rationally designed 4-nitrophenyl-based molecular clefts functionalized with thiourea (L1) and urea (L2) have been synthesized and studied for a variety of anions by UV-Vis and colorimetric techniques in DMSO. Results from the binding studies suggest that both L1 and L2 bind halides showing the order: fluoride > chloride > bromide > iodide; and oxoanions showing the order: dihydrogen phosphate > hydrogen sulfate > nitrate > perchlorate. Each receptor has been shown to form a 1:1 complex with an anion via hydrogen bonding interactions, displaying distinct color change for fluoride and dihydrogen phosphate in solution. As compared to the urea-based receptor L2, the thiourea-based receptor L1 exhibits stronger affinity for anions due the presence of more acidic thiourea functional groups.

Two new species of Balacha (Insecta: Hemiptera: Cicadellidae: Cicadellinae) from Brazil with comments on their phylogenetic position and biogeography

The sharpshooter genus Balacha Melichar, 1926 has seven recognized species and is distributed in southern South America (Argentina, Brazil, Paraguay, and Uruguay). Here, two new Brazilian species of this genus are described and illustrated, one (B. ancora sp. nov.) from Serra do Caraça and Serra do Cipó (Minas Gerais State) and another (B. nigroflava sp. nov.) from Ponta Grossa (Paraná State) and Passo Fundo (Rio Grande do Sul State). Based on 67 morphological characters, we carried out a parsimony analysis to estimate the phylogenetic position of the two new species. Using implied weighting in TNT, a single topology within Balacha was obtained with k values that varied from 1.599 to 7.412. In this topology, the two new taxa appeared within the clade of black Balacha species. A biogeographical analysis (S-DIVA) suggested that the ancestral area of distribution of Balacha was the Atlantic Forest domain. Balacha species were so far known to have only Eryngium (Apiaceae) species as host plants. Here we report a new host plant for the genus: B. ancora sp. nov. specimens were collected on Actinocephalus polyanthus (Eriocaulaceae). Balacha similis and B. rubripennis are newly recorded from Argentina and specimens of the latter have a very distinct color pattern from the typical Brazilian specimens. Finally, a key to species and maps showing the known distribution of the genus are given (several state records of species are also provided).

Anthocyanins from the Red Juvenile Leaves of Loropetalum Chinense var. rubrum (Chinese Fringe Flower) Identification and pH Sensing Behaviors

<p>In this study, anthocyanins were extracted from the frozen juvenile leaves of <i>Loropetalum Chinense</i> var. <i>rubrum</i><b> </b>with high efficiency using ethanol containing 0.1% HCl as extractant. After being purified with AB-8 resin, this extract was investigated with HPLC-DAD-MS/MS determination, and six anthocyanins were identified according to chromatogram, MS data and ratios of absorbance at 400-460 nm to that at absorption maximum (~520 nm), A_400-460/A₅₂₀. Besides cyanidin 3-O-glucoside, peonidin 3-O-glucoside, malvidin 3-O-glucoside, the most abundant malvidin 3,5-O-diglucoside was confirmed through preparative HPLC separation and ¹H NMR determination. However, two delphinidin- and petunidin-derived anthocyanins should be further clarified whether they are 3,5-O-diglucoside or 5-O-glucobioside. In addition, a novel anthocyanin, 2H-pyran[5,6]malvidin 3-O-glucobioside was also proposed yet need more data to confirm. Moreover, malvidin 3,5-O-diglucoside showed excellent pH sensing ability, displaying distinct color change from pink (pH 1.5) to colorlessness (pH 5.5), to blue (pH 6.8) and finally green (pH 8.8 to pH 10.5). All these should be helpful to evaluate this plant as natural pigment resource. </p>

Anthocyanins from the Red Juvenile Leaves of Loropetalum Chinense var. rubrum (Chinese Fringe Flower) Identification and pH Sensing Behaviors

<p>In this study, anthocyanins were extracted from the frozen juvenile leaves of <i>Loropetalum Chinense</i> var. <i>rubrum</i><b> </b>with high efficiency using ethanol containing 0.1% HCl as extractant. After being purified with AB-8 resin, this extract was investigated with HPLC-DAD-MS/MS determination, and six anthocyanins were identified according to chromatogram, MS data and ratios of absorbance at 400-460 nm to that at absorption maximum (~520 nm), A_400-460/A₅₂₀. Besides cyanidin 3-O-glucoside, peonidin 3-O-glucoside, malvidin 3-O-glucoside, the most abundant malvidin 3,5-O-diglucoside was confirmed through preparative HPLC separation and ¹H NMR determination. However, two delphinidin- and petunidin-derived anthocyanins should be further clarified whether they are 3,5-O-diglucoside or 5-O-glucobioside. In addition, a novel anthocyanin, 2H-pyran[5,6]malvidin 3-O-glucobioside was also proposed yet need more data to confirm. Moreover, malvidin 3,5-O-diglucoside showed excellent pH sensing ability, displaying distinct color change from pink (pH 1.5) to colorlessness (pH 5.5), to blue (pH 6.8) and finally green (pH 8.8 to pH 10.5). All these should be helpful to evaluate this plant as natural pigment resource. </p>