Effect of viewing environments on perceived display neutral point.

In this study, the influences of ambient chromaticity, ambient luminance, and display luminance on the perceived neutral point of a display were systematically investigated using 25 experimental settings. The results show that the surround ratio, i.e., the ratio of the ambient luminance to the display luminance, had a greater effect on the display neutral point perception than the absolute intensity of each factor. As the surround ratio decreased, indicating that the display luminance was higher than the ambient luminance, the perceived display neutral point changed from the adapted white to the neutral point in the darkroom condition (corresponding to a surround ratio of zero) at approximately 7,200 K. When the surround ratio exceeded 1.0, the neutral point of the display gradually shifted toward specific levels. The correlated color temperatures of the perceived display neutral points converged to 5,000 and 5,900 K under ambient lighting conditions of 3,000 and 5,000 K, respectively.

Reducing the CIE colorimetric matching failure on wide color gamut displays.

Color matching experiments were conducted for 11 pairs of displays, using 7 displays with different spectral characteristics. The color matching results between the LCD display and displays that have a narrowband spectrum, such as a laser projector, QLED, or OLED, demonstrated a significant color difference between two matched colors. The maximum difference was 18.52 ΔE00, which indicates the white color difference between the LCD and laser projector. There was also a clear observer variability of 2.27 ΔE00. The new cone fundamental function derived from 757 metameric pairs showed good performance compared to CIE standard observers reducing the display color mismatching significantly. This function also demonstrated a better performance when evaluating color matching in color chart image.

Preferred display white prediction model based on mixed chromatic adaptation between "prototypical display white" and surround lighting color.

The correlated color temperature (CCT) of the monitor white needs to be controlled for the preferred image reproduction according to the surround lighting changes. The preferred display white prediction model according to the surround lighting color is proposed both for the emissive transparent display and opaque displays. To develop the model, the preferred CCT of the monitor white of a simulated emissive transparent display and an opaque display were investigated under four different surround lighting CCTs by conducting psychophysical experiments with twenty subjects.

Experimental method for measuring color appearance shifts in high-dynamic-range luminance conditions.

We present an experimental method to determine color appearance shifts under high-dynamic-range conditions. A couple of light booths with variable luminance provide high-dynamic-range luminance conditions, and a perceptual color shift between the two booths is determined using color appearance matching. For red, green, yellow, and blue groups of four surface color samples, color shifts were measured for nine subjects under a dual illumination at background luminance levels of $100\,\,{{\rm cd/m}^2}$100cd/m2 and $4700\,\,{{\rm cd/m}^2}$4700cd/m2. We observed significant perceptual hue shifts toward blue with magnitudes of 2.5 to 3.9 and 5.0 to 6.9 CIELAB units, for the red and green samples, respectively, and decreases in chroma for most samples when changed from low to high luminances.

Transparent effect on the gray scale perception of a transparent OLED display.

Gray scale perception of transparent OLED displays was explored. The difference in luminance between transparent and non-transparent stimuli in the overall gray range was compared. The transparent effect appeared in gray scale perception. The range of the transparent effect was determined experimentally. To explore the practical application of this effect, we proposed a new tone-curve based on the transparent effect. In the preference experiment, participants indicated a higher preference score for the new tone-curve. This implied that the transparent effect is valid and applicable to real situations.

Monitor brightness changes under a wide range of surround conditions.

Display brightness data were collected under a wide range of surround conditions. A 24 in. (60.96 cm) LCD display was used to generate color stimuli, and a 107 in. (271.78 cm) two-dimensional illuminator was used to generate various surround conditions. The brightness values of the display under 89 monitor-surround-luminance combinations were collected from 10 or 24 observers. The surround ratio, SR, i.e., the luminance ratio between the surround and the monitor, varied from 0 to 90. Based on the collected brightness data, we propose a new c value as the log function of the surround ratio, SR, to improve the performance of the CIECAM02 brightness predictor Q.

Discovery of diamide compounds as diacylglycerol acyltransferase 1 (DGAT1) inhibitors.

Diamide compounds were identified as potent DGAT1 inhibitors in vitro, but their poor molecular properties resulted in low oral bioavailability, both systemically and to DGAT1 in the enterocytes of the small intestine, resulting in a lack of efficacy in vivo. Replacing an N-alkyl group on the diamide with an N-aryl group was found to be an effective strategy to confer oral bioavailability and oral efficacy in this lipophilic diamide class of inhibitors.

Visual appearance measurement of surfaces containing pearl flakes.

The color, gloss, and texture (i.e., pearliness) of 15 glossy samples containing pearl flakes were investigated. Psychophysical experimental data from 21 observers were compared with measurement data. Color measurement data obtained using the CIE D/0 and ASTM E2539-08 multiangle geometry did not predict the overall color appearance variation of pearly samples. Pearly samples have a lower perceived glossiness than non-pearly surfaces with the same level of gloss treatment, but a much higher measured gloss. Pearliness describes the texture of pearly samples well and can be predicted as a function of the pearl flakes' average size and area coverage measured from magnified surface images. These results suggest that an image statistics approach is required to properly describe the visual appearance of pearly surfaces.

Concise Synthesis of Broussonone A.

A concise and expeditious approach to the total synthesis of broussonone A, a p-quinol natural compound, has been developed. The key features of the synthesis include the Grubbs II catalyst mediated cross metathesis of two aromatic subunits, and a chemoselective oxidative dearomatizationin the presence of two phenol moieties. Especially, optimization associated with the CM reaction of ortho-alkoxystyrenes was also studied, which are known to be ineffective for Ru-catalyzed metathesis reactions under conventional reaction conditions because ortho-alkoxy group could coordinate to the ruthenium center, resulting in the potential complication of catalyst inhibition.

Synthesis of xanthone derivatives based on α-mangostin and their biological evaluation for anti-cancer agents.

A xanthone-derived natural product, α-mangostin is isolated from various parts of the mangosteen, Garcinia mangostana L. (Clusiaceae), a well-known tropical fruit. Novel xanthone derivatives based on α-mangostin were synthesized and evaluated as anti-cancer agents by cytotoxicity activity screening using 5 human cancer cell lines. Some of these analogs had potent to moderate inhibitory activities. The structure-activity relationship studies revealed that phenol groups on C3 and C6 are critical to anti-proliferative activity and C4 modification is capable to improve both anti-cancer activity and drug-like properties. Our findings provide new possibilities for further explorations to improve potency.

Discovery of a novel class of diacylglycerol acyltransferase 2 inhibitors with a 1H-pyrrolo[2,3-b]pyridine core.

Diacylglycerol acyltransferase 2 (DGAT2), which catalyzes the final step in triacylglycerol (TG) synthesis, is a key enzyme associated with hepatic steatosis and insulin resistance. Here, using an in vitro screen of 20000 molecules, we identified a class of compounds with a substituted 1H-pyrrolo[2,3-b]pyridine core which proved to be potent and selective inhibitors of human DGAT2. Of these compounds, H2-003 and -005 exhibited a considerable reduction in TG biosynthesis in HepG2 hepatic cells and 3T3-L1 preadipose cells. These compounds exert DGAT2-specific-inhibitory activity, which was further confirmed in DGAT2- or DGAT1-overexpressing HEK293 cells. In addition, these compounds almost completely abolished lipid droplet formation in 3T3-L1 cells when co-treated with a DGAT1 inhibitor, which was not attained using either a DGAT2 or DGAT1 inhibitor alone. Collectively, we identified two DGAT2 inhibitors, H2-003 and -005. These compounds will aid in DGAT2-related lipid metabolism research as well as in therapeutic development for the treatment of metabolic diseases associated with excessive TG.

Identification and validation of a selective small molecule inhibitor targeting the diacylglycerol acyltransferase 2 activity.

Diacylglycerol acyltransferase 2 (DGAT2) is one of two distinct DGAT enzymes that catalyze the last step in triacylglycerol (TG) synthesis. Findings from previous studies suggest that inhibition of DGAT2 is a promising strategy for the treatment of hepatic steatosis and insulin resistance. Here, we identified compound 122 as a potent and selective inhibitor of human DGAT2, which appeared to act competitively against oleoyl-CoA in vitro. The selective inhibition of DGAT2 was also confirmed by the reductions in enzymatic activity and de novo TG synthesis in DGAT2-overexpressing HEK293 cells and hepatic cells HepG2. Compound 122, as a newly identified inhibitor of DGAT2, will be useful for the research on DGAT2-related lipid metabolism as well as the development of therapeutic drug for several metabolic diseases.

Design and synthesis of 4-O-methylhonokiol analogs as inhibitors of cyclooxygenase-2 (COX-2) and PGF1 production.

A series of novel 4-O-methylhonokiol analogs were synthesized in light of revealing structure-activity relationship for inhibitory effect of COX-2 enzyme. The key strategy of the molecular design was oriented towards modification of the potential metabolic soft spots (e.g., phenol and olefin) or by altering the polar surface area via incorporating heterocycles such as isoxazole and triazole. Most of all exhibited the inhibitory effects on COX-2 and PGF(1) production but not macrophage NO production. Especially, aryl carbamates 10 and 11 exhibited more potent inhibitory activity against COX-2 and PGF(1) production.

Novel GPR43 Agonists Exert an Anti-Inflammatory Effect in a Colitis Model.

GPR43 (also known as FFAR2), a metabolite-sensing G-protein-coupled receptor stimulated by short-chain fatty acid (SCFA) ligands is involved in innate immunity and metabolism. GPR43 couples with Gαi/o and Gαq/11 heterotrimeric proteins and is capable of decreasing cyclic AMP and inducing Ca2+ flux. The GPR43 receptor has additionally been shown to bind ß-arrestin 2 and inhibit inflammatory pathways, such as NF-ΚB. However, GPR43 shares the same ligands as GPR41, including acetate, propionate, and butyrate, and determination of its precise functions in association with endogenous ligands, such as SCFAs alone, therefore remains a considerable challenge. In this study, we generated novel synthetic agonists that display allosteric modulatory effects on GPR43 and downregulate NF-ΚB activity. In particular, the potency of compound 187 was significantly superior to that of preexisting compounds in vitro. However, in the colitis model in vivo, compound 110 induced more potent attenuation of inflammation. These novel allosteric agonists of GPR43 clearly display anti-inflammatory potential, supporting their clinical utility as therapeutic drugs.

A new structural alert for benzimidazoles: 2,6-dimethylphenyl substituents increase mutagenic potential and time-dependent CYP3A4 inhibition risk.

A series of 2-[(2,6)-dimethylphenyl]benzimidazole analogs displayed strong potential for mutagenicity following metabolic activation in either TA98 or TA100 Salmonella typhimurium strains. The number of revertants was significantly reduced by replacing the 2,6-dimethylphenyl group with a 2,6-dichlorophenyl moiety. Time-dependent CYP3A4 inhibition was also observed with a compound containing a 2-[(2,6)-dimethylphenyl] benzimidazole ring, implying risk for this scaffold to generate reactive metabolites.

Syntheses of sulfur and selenium analogues of pachastrissamine via double displacements of cyclic sulfate.

Bioisosteric analogues of pachastrissamine that contain sulfur and selenium atoms replacing the oxygen in the ring system, were efficiently prepared from a cyclic sulfate intermediate by sequential intermolecular and intramolecular S(N)2 displacement reactions of the dianions. The analogues exhibited cytotoxicities comparable to that of pachastrissamine.

Efficient and convenient preparation of 3-aryl-2,2-dimethylpropanoates via Negishi coupling.

An efficient and convenient Negishi coupling protocol was developed for the preparation of 3-aryl-2,2-dimethylpropanoates providing easy access to key pharmaceutical intermediates that often require multi-step synthesis using conventional enolate chemistry.

Rapid Access to the Structural Core of Aflavinines via Stereoselective Tandem Intramolecular Diels-Alder Cycloaddition Controlled by the Allylic 1,3-Strain.

An expedient route to access the functionalized structural core of aflavinines has been developed starting from three readily available fragments over 12 steps in 29.1% overall yield without using any transition metal catalysis. The key feature of this approach is a tandem intramolecular Diels-Alder cycloaddition to complete the hexacyclic framework with the correct stereochemistry and all the requisite structural elements in place to achieve the total synthesis of aflavinine and its congeners.

Generating vivid colors on red-green-blue-white electonic-paper display.

Color characteristics of an RGBW (red, green, blue, white) electrophoretic display (EPD) prototype developed by Samsung Electronics are analyzed. EPD shows strong crosstalk between subpixels because of both the fringe field between subpixels and the scattering phenomena at the display surface. An RGB-to-RGBW color-decomposition algorithm optimized to EPD characteristics is developed that compensates for color deterioration due to the fringe field and scattering phenomena. For the four-color-decomposition algorithm, white is added to the primary colors to enhance the reflectance of the vivid colors while minimizing chroma loss. The psychophysical experimental result shows that images rendered with the algorithms developed in this study are preferred more than 90% of the time over those rendered with algorithms from previous studies. This research proves that, in spite of the limited physical property of EPD, the color quality can be improved dramatically through the use of well-designed color-rendering algorithms.

Facile ring opening reaction of oxazolone enables efficient amidation for aminoisobutyric acid.

4,4-Dimethyloxazolones derived from N-protected aminoisobutyric acid (AIB) are particularly known as poor electrophiles due to the steric hindrance around the carbonyl and not employed as useful intermediates for amidation whereas numerous examples have been reported to support the utility of other oxazolones in amidation. AIB is an important and strategical synthon in medicinal chemistry but the peptide bond formation of the N-protected urethane derivatives of AIB is known to be often unproductive due to the rapid formation of the stable 4,4-dimethyloxazolone via an intramolecular cyclization. We discovered that the 4,4-dimethyloxazolone of an AIB urethane is in fact an excellent electrophile that enables efficient amidation even with weakly reactive nucleophiles. The 4,4-dimethyloxazolone can be stored in a pure form and used as a reagent offering an efficient and convenient synthetic tool for generating AIB-peptide analogs.