Yellow-orange Color Research Articles

Electrosynthesis and Electrochromism of a New Crosslinked Polydithienylpyrrole with Diphenylpyrenylamine Subunits

A new electroactive monomer with two 2,5-di(2-thienyl)pyrrole (SNS) units and one diphenylpyrenylamine (DPPA) subunit, namely N,N-bis(4-(2,5-di(2-thienyl)-1H-pyrrol-1-yl)-phenyl)-1-aminopyrene (DPPA-2SNS), was synthesized from 1,4-di-(2-thienyl)butane-1,4-dione with N,N-di(4-aminophenyl)-1-aminopyrene through the Paal–Knorr condensation reaction. Visible and near-infrared (NIR) electrochromic polymer films could be facilely generated on the ITO-glass surface by the electrochemical polymerization of DPPA-2SNS in an electrolyte solution. The electro-synthesized polymer films exhibit multi-staged redox processes and multi-colored anodic electrochromic behavior. A multi-colored electrochromism, with yellowish orange, greyish blue, and purplish black colors, was observed in the polymer film by applying a positive potential. The polymer films exhibit reasonable coloration efficiency, fast response time, and good cycling stability, especially when switched between neutral and the first oxidation states. For comparison, N-(1-pyrenyl)-2,5-di(2-thienyl)pyrrole (Py-SNS) was also prepared and characterized with electrochemical and electro-optical properties.

Pollination of the Orchid Habenaria rhodocheila by the Swallowtail Butterfly Papilio helenus in Subtropical Evergreen Broad-Leaved Forests in Southern China

Habenaria rhodocheila is different from other species in the genus as it has bright yellow-orange, orange-red or red floral colors and grows in subtropical evergreen broad-leaved forests. It is listed as a level II protected plant in China. This study focused on details of the pollination mechanism, including floral structure, the pollinator and its behavior, the pollination process, and fruit set in its natural environment compared to controlled artificial pollination. Our results showed that the flowers of H. rhodocheila are self-compatible, but rely on a pollinating agent due to the lack of an automatic self-pollination mechanism. At three sites the flowers of H. rhodocheila were frequently pollinated by a species of the swallowtail butterfly Papilio helenus L. During pollination, the butterfly inserts its proboscis into the spur aperture. The base of the proboscis then contacts the viscidia and the pollinarium sticks to the insect, followed by contact between pollinia and stigmas. The length of the proboscis of P. helenus is comparable to, but slightly shorter than the length of the floral spur. The pollination activity generally occurs between 9:30 AM to 1:30 PM daily and is especially frequent between 10:30 AM and 11:30 AM. These results suggest that the similarity between the length of the butterfly's proboscis and the length of the orchid's spur is a major factor contributing to the efficient pollination of H. rhodocheila in its natural habitat. Most species in Habenaria are moth-pollinated, whereas our research has shown that H. rhodocheila in subtropical evergreen broad-leaved forests in China is specifically adapted to butterfly pollination by P. helenus.

A review on extending storage life of kinnow

Kinnow is an important crop widely cultivated in the north western part of India. Shelf life is an important part of kinnow mandarin and is possible only by using various organic, inorganic and growth regulators. Kinnow fruits are attractive because of its orange yellow colour rind and gains better market potential that helps to obtain assured income by growers. So in this current review put an effort to address the role of various waxes, packaging materials, fungicides, and plant extracts helps in an extending the storage life of kinnow. Kinnow fruits acquire greater demand in Indian markets as well as in foreign nationals.

Synthesis of Flavonoid Pigments in Grain of Representatives of Poaceae: General Patterns and Exceptions in N.I. Vavilov’s Homologous Series

Flavonoid pigments are a group of secondary plant metabolites. Interest in these compounds is determined by a wide range of their biological properties; thus the saturation of edible parts of plants, in particular, cereal grains, with flavonoids is an urgent task today. The synthesis of flavonoid pigments can be observed in the testa, pericarp, aleurone layer, and grain endosperm in representatives of most cereal crops (maize Zea mays L., rice Oryza sativa L., bread wheat Triticum aestivum L., barley Hordeum vulgare L., rye Secale cereale L., sorghum Sorghum bicolor (L.) Moench., etc.), which is consistent with N.I. Vavilov’s law of homologous series in hereditary variation. However, according to some features, certain types of variability are not observed: for example, in some representatives of the tribe Triticeae, no forms synthesizing anthocyanins in the aleurone layer are found. Homologous series have not been identified for some unique features. For example, compounds belonging to the group of 3-deoxyanthocyanidins having a yellow-orange color uncharacteristic of cereal crops are synthesized in the pericarp only in sorghum. This review provides information on the genetic diversity and biosynthesis of flavonoid pigments in the cereal grains, characterizing the nature of the observed patterns and exceptions to Vavilov’s law.

Dermoscopy of Juvenile Xanthogranuloma

Background: Dermoscopy is useful for the evaluation of juvenile xanthogranuloma (JXG). The classical “setting sun” pattern is characteristic of JXG, but its sensibility appears to be limited. An extensive description of other dermoscopic findings is not available in the literature. Objectives: The aim of this study was to valuate and describe the clinical and dermoscopic characteristics of a series of JXG cases. Methods: This is a retrospective descriptive study, including cases with histopathologic diagnosis of JXG, and the availability of clinical and dermoscopic images, assessed for the presence of dermoscopic features based on the available literature. Results: A total of 17 lesions were analyzed. 70.6% showed global symmetry, 35.3% presented the typical “setting sun” pattern. All lesions showed yellow-orange and/or pink-red structureless color. Other dermoscopic features were yellow globules (35.3%), shiny white streaks (23.5%), brown globules (17.6%), pale-brown network (11.8%), negative network (11.8%), erosion/ulceration (11.8%), rosettes (5.9%), and hemorrhage (5.9%). Scales were seen in 64.7% of patients. Vascular structures were observed in all the lesions, mostly in an irregular distribution (76.5%). The observed vessel types were dotted (52.9%), linear (52.9%), branching-arboriform (29.4%), comma-like (23.5%), hairpin-like (17.6%), globular (17.6%), coiled (11.8%), and milky-red globules (5.9%). Conclusions: Symmetry, yellow/orange-pink/red color, yellow globules, shiny white streaks, and irregularly distributed different types of vascular structures are the main dermoscopic features of JXG. This is the largest dermoscopic registry of JXG published to date.

Influence of enzyme source and catechins on theaflavins formation during in vitro liquid-state fermentation

Theaflavins (TFs) are the main components responsible for the bright, orange-yellow color of liquor and fresh, brisk, and astringent taste of black tea. TFs are formed from the enzymatic oxidative condensation of catechins. In this study, we aimed to optimize the production of TFs from catechins in an in vitro liquid-state fermentation system. We examined (1) three different enzyme sources (2) two different times for the addition of catechins and (3) three different ratios (1:2, 1.5:1.5, and 2:1) of key catechins [(−)-epigallocatechin (EGC); (−)-epigallocatechin gallate (EGCG)]. The results indicated that the use of polyphenol oxidase (PPO) promoted a rapid and uniform consumption of catechins, resulting in a sustained high-level production of TFs. The batchwise addition of catechins was the best method for sustained and high-efficiency TFs formation. An EGC/EGCG ratio of 1:2 led to the formation of relatively higher amounts of theaflavin-3ʹ-gallate (TF-3ʹ-G) and TF-3,3ʹ-digallate (TF-D-G), which resulted in a significantly higher total TFs content. These results demonstrate that the batchwise addition of catechin substrates with a high EGCG content using PPO as an enzyme source can improve the formation of TFs. Our results provide a theoretical basis for understanding the mechanisms of TFs synthesis.

Curcumin - Properties, Applications and Modification of Structure

In recent years, the interest in biologically active compounds of natural origin has increased significantly. Researchers' research focuses on increasing the activity of curcumin by forming complexes with metals such as vanadium, iron, copper or gallium. Introduction of metal compounds to curcumin increases the scope of application in pharmacology. The main direction of research development is the treatment of tumors, among others stomach cancer or leukemia. Curcuminoids are the main components of turmeric (Curcuma longa L.), a plant from India and South-East Asia. Due to its intense yellow-orange color and pleasant aroma, the powdered rootstalk is widely used in the food industry, as natural dye and spice. The chemical compound responsible for the characteristic color of rhizomes of curcuma is 1,6-heptadien-3,5-dione-1,7-bis(4-hydroxy-3-methoxyphenyl) - (1E, 6E) called curcumin. This work aims to characterize curcumin in terms of its structure, therapeutic properties and also as a substrate for the synthesis of valuable derivatives like tetrahydrocurcumin. Knowledge about this relationship based on literature analysis will enable a better understanding of the factors responsible for its biological activity.

Синтез и исследование новых азокрасителей на основе функционально замещенных производных салициловой кислоты

Three chromatographically pure azo dyes based on salicylic acid and para-nitroaniline were isolated in 60-64% yields. The structure of the synthesized compounds was proved by IR spectroscopy. The spectra of the compounds contain characteristic absorption bands associated with the vibrations of O–H, N–H, C=O, and N=N groups. The products precipitated as orange-brown powders, which corresponds to compounds with a short system of conjugated double bonds. The predominant tautomeric form of existence of the synthesized azo compounds was determined – 5,5'-(diazen-1,2-diyl)bis(2-hydroxybenzoic acid), 2-hydroxy-5-((4-nitrophenyl)-diazenyl)benzoic acid, 5-amino-2-hydroxy-4-((4-nitrophenyl) diazenyl) benzoic acid. It was shown that they all exist as azo-tautomers. To determine the dyeing power of potential dyes, a test cold dyeing was carried out on samples of a multichannel consisting of six main types of fabrics used in the textile industry, under conditions corresponding to dyeing with acid and reactive dyes. The ability of the compounds to act as acid dyes was established, coloring woolen, polyamide and acetate fibers in yellow-orange and beige-brown colors. The introduction of an amino group into the salicylic acid fragment weakens the color properties of the azo dye molecule. The calculation of the toxicity of compounds with intravenous and oral routes of administration, carried out according to the GUSAR program, shows their low toxicity (4-5 toxicity class). The introduction of an amino group into the azo dye molecule is accompanied by an increase in its toxicity. All isolated compounds comply with Lipinski's rule, which indicates their bioavailability. Prediction of the biological activity of the compounds, carried out using the PASS program, shows that with a probability of more than 90%, the synthesized compounds exhibit antiseptic properties without irritating the skin and mucous membranes. This allows the isolated compounds to be considered promising for use as dyes in cosmetics.

C3-symmetric triaminoguanidine based colorimetric and fluorometric chemosensor: Sequential detection of Zn2+/PPi, its RGB performance for detection of Zn2+ ion and construction of IMPLICATION logic gate

In this work, new ethyl(E)-2-cyano-3-(1H-pyrrol-2-yl)acrylate appended C3-symmetric star-shape triaminoguanidine based Schiff base (LH3) was designed and synthesized from simple synthons. New probe, LH3 was completely analyzed by 1H NMR, 13C NMR and mass spectrum. In the present probe LH3, effective π-conjugated ethyl(E)-2-cyano-acrylate unit was introduced on the periphery of the pyrrole-triaminoquanidine conjugates by using carefully chosen building units. The probe LH3 shows high selectivity and sensitivity towards Zn2+ ion via colorimetric and fluorometric changes. The yellowish orange color of LH3 solution turned to wine red color upon addition of Zn2+ solution, along with red shifted absorption maxima from 450nm to 550nm, this indicates the formation of LH3-Zn2+ species. Job's plot and mass spectrum analysis confirms the formation of 1:3 stoichiometric complex between the LH3 and Zn2+ ions. Further this ensemble shows selective detection towards PPi anion over the other anions based on displacement metal ion approach. Hence, reversible colorimetric/emission response of LH3 towards Zn2+ and PPi ions via "on-off-on" manner could allow the construction of IMPLICATION logic gate functions. The practical efficacy of the probe LH3 was established by utilization of the probe for the detection of Zn2+ ions in real water sample analysis. Further, the significant noticeable colorimetric changes of the probe LH3 upon addition of Zn2+ ion have been successfully integrated with a smartphone app RGB color value to construct a real-time analysis of Zn2+ ions.

COUNTCOLORS, AN R PACKAGE FOR QUANTIFICATION OF THE FLUORESCENCE EMITTED BY PSEUDOGYMNOASCUS DESTRUCTANS LESIONS ON THE WING MEMBRANES OF HIBERNATING BATS.

Pseudogymnoascus destructans colonizes the wing membrane of hibernating bats with the potential to form dense fungal hyphae aggregates within cupping erosions. These fungal cupping erosions emit a characteristic fluorescent orange-yellow color when the wing membrane is transilluminated with 385 nm ultraviolet (UV) light. The purpose of this study was to create and validate the R package, countcolors, for quantifying the distinct orange-yellow UV fluorescence in bat-wing membrane lesions caused by P. destructans. Validation of countcolors was completed by first quantifying the percent area of 20, 2.5 cm2 images. These generated images were of two known pixel colors ranging from 0% to 100% of the pixels. The countcolors package accurately measured the known proportion of a given color in each image. Next, 40, 2.5 cm2 sections of UV transilluminated photographs of little brown bat (Myotis lucifugus) wings were given to a single evaluator. The area of fluorescence was both manually measured and calculated using image analysis software and quantified with countcolors. There was good agreement between the two methods (Pearson's correlation=0.915); however, the manual use of imaging software showed a consistent negative bias. Reproducibility of the analysis methods was tested by providing the same images to naive evaluators who previously never used the software; no significant difference (P=0.099) was found among evaluators. Using the R package countcolors takes less time than does manually measuring the fluorescence in image analysis software, and our results showed that countcolors can improve the accuracy when quantifying the area of P. destructans infection in bat wing-membranes.

Two new sponge species (Demospongiae: Chalinidae and Suberitidae) isolated from hyperarid mangroves of Qatar with notes on their potential antibacterial bioactivity.

This study presents the taxonomic description of two new sponge species that are intimately associated with the hyperarid mangrove ecosystem of Qatar. The study includes a preliminary evaluation of the sponges’ potential bioactivity against pathogens. Chalinula qatari sp. nov. is a fragile thinly encrusting sponge with a vivid maroon colour in life, often with oscular chimneys and commonly recorded on pneumatophores in the intertidal and shallow subtidal zone. Suberites luna sp. nov. is a massive globular-lobate sponge with a greenish-black colour externally and a yellowish orange colour internally, recorded on pneumatophores in the shallow subtidal zone, with large specimens near the seagrass ecosystem that surrounds the mangrove. For both species, a drug extraction protocol and an antibacterial experiment was performed. The extract of Suberites luna sp. nov. was found to be bioactive against recognized pathogens such as Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis, but no bioactive activity was recorded for Chalinula qatari sp. nov. This study highlights the importance of increasing bioprospecting effort in hyperarid conditions and the importance of combining bioprospecting with taxonomic studies for the identification of novel marine drugs.

Analisis Kualitatif dan Kuantitatif Metabolit Sekunder Ekstrak Etanol Buah Okra (Abelmoschus esculentus L. Moench) dengan Metode Spektrofotometri UV-Vis

This study aims to determine the content of secondary metabolites and the levels of total secondary metabolites in ethanol extract of Okra (Abelmoschus esculentus L. Moench) fruit with UV-Vis Spectrophotometry method. Okra (Abelmoschus esculentus L. Moench) fruit extract was prepared by maceration method with 96% ethanol. The extract was concentrated using a rotary evaporator that followed by a qualitative test for alkaloids, flavonoids, saponins, and tannins using suitable reagents with the test parameters, while for the qualitative assay using a UV-Vis Spectrophotometry. Qualitative analysis of alkaloids using test parameters of total alkaloids equivalent to quinine, flavonoid using parameter of total flavonoids equivalent to quercetin, saponin using parameters of standard saponins total from the Quillaja Bark, and tannin using test parameters of total tannins equivalent to tannic acid. Qualitative test results indicated that the ethanol extract of Okra fruit tested positive for alkaloids content wich characterized by the orange deposition, flavonoids characterized by the formation of an orange-yellow color, a stable foam for saponins and tannins marked in black. The quantitative analysis resulted alkaloids of 2228.06 mg/gram, flavonoids of 2.79 mg/gram, saponins of 10.03 mg/gram, and tannins of 1973.27 mg/gram.
 Keywords: Okra fruit, secondary metabolites, UV- Vis spectrophotometry, qualitative, quantitative.

Improved luminescence and LPG sensing properties of Sm3+-doped lanthanum aluminate thin films

Undoped and (1 mol%) Sm3+-doped LaAlO3 nanoparticles were synthesized by solution combustion technique utilizing sucrose as fuel. These rhombohedral perovskite nanoparticles thin films were prepared by spin coating on the ITO glass substrate. The XRD, SEM and TEM results show that the 40–60 nm crystallites are formed. The Photoluminescence Emission spectra and CIE coordinates show the enhancement of the yellowish orange color from Sm3+-doped LaAlO3 nanoparticles under the excitation wavelength of 406 nm. LPG detection was carried out for 0–1000 ppm concentrations. The sensor response of the Sm3+-doped LaAlO3 thin films was perceived to be > 87% for the detection of LPG through enhanced response as well as recovery time. Also, the stability analysis implied that the % sensor response remained favorably steady over a time period of 30 days. Owing to the improved % sensor response, quick response and recovery along with greater stability, these thin-film sensors showed better applications for detection of LPG leakage at room temperature.

<p><strong><em>Gastrodia gunatillekeorum </em></strong><strong>(Gastrodieae, Epidendroideae, Orchidaceae), a new species from a lowland rainforest of Sri Lanka</strong></p>

Gastrodia gunatillekeorum, a new species in the family Orchidaceae, is described and illustrated from a tropical lowland rainforests of Sri Lanka. It is morphologically close to G. spatulata which is endemic to Indonesia owing to the white flower front with yellowish-orange colour on the inner wall of perianth tube and free part of perianth tube reflexed backwards. However, these two species can be very well differentiated on the basis of spathulate to linear petals which are shorter than sepals, fused only at the base and present inside the perianth tube; labellum elongate-elliptic and column broadest in the middle part in G. spatulata, whereas petals as long as sepals with apical 1/3rd part free (rest fused with sepals) and reflexed backwards, labellum rhomboid in shape, column broadest towards the apex in G. gunatillekeorum. Taxonomic account, line drawing, color photographs and conservation assessment are provided for the new species.

Skin Color Cues to Human Health: Carotenoids, Aerobic Fitness, and Body Fat.

Colorful carotenoid ornaments are sexually selected signals of health in many species. In humans too, carotenoids could provide a perceptible cue to health as they impart an attractive yellow-orange color to skin. Increasing carotenoid pigmentation and skin yellowness is associated with increased fruit and vegetable intake, but whether other aspects of human health benefit skin color is unknown. Carotenoids, as antioxidants, help maintain oxidative balance but are expended in this role. Therefore, any health factor affecting oxidative balance could alter the quantity of carotenoids available to color skin. Exercise increases endogenous antioxidant capacity and consequently may decrease expenditure of carotenoids. Fitness could also raise skin carotenoids by lowering body fat (a source of oxidative stress). Here we investigate the relationship between skin color (measured spectrophotometrically), aerobic fitness (measured by estimating the maximum volume of oxygen that a person can use per unit of time, VO2 max), and body fat. In a cross-sectional design, we find that both higher aerobic fitness and lower body fat are predictors of skin yellowness, independent of each other and dietary fruit and vegetable intake. In a longitudinal design over 8 weeks, we found that increase in fitness and decrease in body fat were independently associated with an increase in skin yellowness. Change in self-reported stress and sleep were further predictors of skin yellowness indicating a more general relation between health and skin tone. Simulations of the skin color associated with higher fitness were found to appear healthier. Hence, our results suggest that increasing cardiovascular fitness and decreasing fat levels produce a healthier skin color. Such findings have repercussions for public health because improved attractiveness can provide an incentive for a healthier lifestyle, including exercise and weight regulation.

THE STUDY OF THE CAROTENOID COMPOSITION OF THE FRUITS OF SEA BUCKTHORN DIFFERENT VARIE-TIES BY THIN LAYER CHROMATOGRAPHY

Sea buckthorn (Hippophae rhamnoides L.) is an object of general interest due to the high content of biologically active substances (BAS). Fruits contain water- and fat-soluble vitamins, organic acids, sugars, tannins, amino acids, flavonoids and carotenoids. The latter, in turn, give the fruits a typical yellow-orange color. Carotenoids (α-, β-, and γ-carotenes) make up 11% of the unsaponifiable fraction of sea buckthorn oil and are very valuable compounds for the cosmetics industry. Leading scientists of the world have found that carotenoids have antioxidant, antimutagenic and antitumor properties, and therefore are actively used for the prevention of cancer. The fruits of sea buckthorn are the raw materials for the pharmacopeia drug - sea buckthorn oil and a large number of various herbal medicines based on it. To separate and identify complex compounds, such as carotenoids, considerable attention is paid to the TLC method. In connection with the foregoing objective of the study was the study of the TLC profile of carotenoids of sea buckthorn fruits of various varieties.
 Optimal chromatographic conditions were selected that ensure the best separation of carotenoid zones in a thin sorbent layer. In the used eluting system, satisfactory separation of the chromatographic zones of carotenoids is observed, since the value of sorption selectivity is greater than unity. To characterize the chromatographic profile of each variety, it is proposed to use a value of Rs that is more independent of the influence of various parameters and does not require standards. The difference in the obtained TLC profile of carotenoids of sea buckthorn fruits of representatives of ten different varieties, as well as for the fruits of a wild plant, was established. The maximum number of chromatographic zones is observed for the Ryabinovaya variety, and the minimum for the Stolichnaya variety. It was established that by the method of «fingerprints» it is possible to identify the sort of fruits of sea buckthorn by the type of chromatographic profile of carotenoids.

Designing a logo for renewable energy sources with public participation: Empirical evidence from Greece

This contribution looks into logos as a powerful designing tool which can promote the implementation of Renewable Energy Sources (RES) policy. Given the lack of universal logo which would communicate the RES-derived products and services effectively, we initially explored the public’s emotions, thoughts, perceptions, images, experiences, beliefs and attitudes towards RES and non-RES through their design illustration. Experts decoded a total of 769 RES and 737 non-RES designs of four different sample groups ranging from the less informed children to well-informed engineers, and defined the design variables of a RES logo. On the basis of these design guidelines, professional designers created 60 RES logos. Besides, 432 participants randomly selected evaluated the logos on a score scale from 1 to 6. Interdisciplinary, cross-cultural and semiotic analysis of the winner logo revealed that in order to promote the RES use, a logo should be of round shape; present a sense of movement; convey a clear positive message; embed natural elements in the composition of the image with various hues of green, white and yellow-orange colours; include visually acute, religious and cultural symbols, and carry connotations of personal and social responsibility. This is the first attempt of designing a RES logo with public participation.

Influence of TiO2 charge and BSA-metal ion complexation on retention of Cr (VI) in ultrafiltration process

TiO 2 nanoparticles (NPs), functionalized poly vinyl chloride (PVC) and polysulfone (PSf) were assembled together in different compositions to fabricate composite membranes with potential application in Cr (VI) and antifouling treatment. Here, TiO 2 nanoparticles were synthesized via sol-gel process and Poly vinyl chloride chemically altered with 4-amino benzoic acid. Functionalized PVC was blended uniformly throughout PSf matrix rendering the yellowish-orange color and porous structure giving better productivity. TiO 2 NPs were studied for optimum concentration to provide the excess charge for Cr (VI) rejection. SEM images revealed the porous finger like structure within the membranes and the molecular weight cutoff confirmed the ultrafiltration nature of the membranes. Composites showed good wetting behavior with contact angle (between 67 and 76°) and swelling behavior (≈50–79%). Cr (VI) aqueous rejection and the key parameters namely pressure, pH, filler TiO 2 concentration and BSA protein were studied in detail. Maximum of 87 ± 5% rejection of Cr (VI) was obtained with productivity of 6.5 L/m 2 h at 100 kPa pressure in acidic medium. While the antifouling experiments indicated incorporation of TiO 2 NPs increased the flux recovery ratio, presence of BSA protein in feed solution showed binding effects with Cr 2 O 7 2− anions. The membranes showed good reusability for continuous 3 cycles maintaining the rejection efficiency above 70 ± 5% at the end of 3rd cycle. • Work reports the effect of TiO 2 NPs on performance of 4-amino benzoic acid/PSf membranes. • Presence of BSA feed and interaction between Cr (VI) ions on membrane performance is deliberated. • Complexation between BSA protein and Cr 2 O 7 2− ions lead to increased rejection efficiency with time. • The composite membranes showed improved rejection of Cr (VI) throughout the whole pH range owing to TiO 2 NPs.

ICT and AIE Characteristics Two Cyano-Functionalized Probes and Their Photophysical Properties, DFT Calculations, Cytotoxicity, and Cell Imaging Applications.

Two probes, AIE-1 and AIE-2, were synthesized to investigate the effect of substitutional functional group on aggregation (aggregation-caused quenching (ACQ) or aggregation-induced emission (AIE)) and intramolecular charge transfer (ICT) behavior as well as on the cell imaging aspect. The yellow-color non-substituted probe AIE-1 showed weak charge-transfer absorption and an emission band at 377 nm and 432 nm, whereas the yellowish-orange color substituted probe AIE-2 showed a strong charge-transfer absorption and an emission band at 424 nm and 477 nm in THF solvent. The UV-Vis studies of AIE-1 and AIE-2 in THF and THF with different water fractions showed huge absorption changes in AIE-2 with high water fractions due to its strong aggregation behavior, but no such noticeable absorption changes were observed for AIE-1. Interestingly, the fluorescence intensity of AIE-1 at 432 nm gradually decreased with increasing water fractions and became almost non-emissive at 90% water. However, the monomer-type emission of AIE-2 at 477 nm was shifted to 584 nm with a 6-fold increase in fluorescence intensity in THF-H2O (1:9, v/v) solvent mixtures due to the restriction of intramolecular rotation on aggregation in high water fractions. This result indicates that the probe AIE-1 shows ACQ and probe AIE-2 shows AIE behaviors in THF-H2O solvent mixtures. Furthermore, the emission spectra of AIE-1 and AIE-2 were carried out in different solvent and with different concentrations to see the solvent- or concentration-dependent aggregation behavior. Scanning electron microscope (SEM) and dynamic light scattering (DLS) experiments were also conducted to assess the morphology and particle size of two probes before and after aggregation. Both of the probes, AIE-1 and AIE-2, showed less toxicity on HeLa cells and were suitable for cell imaging studies. Density functional theory (DFT) calculation was also carried out to confirm the ICT process from an electron-rich indole moiety to an electron-deficient cyano-phenyl ring of AIE-1 or AIE-2.

Investigations of enhanced luminescence properties of Sm3+ doped LaAlO3 nanophosphors for field emission displays

LaAlO3: Sm3+ (1–9 mol%) nanophosphors were synthesized using solution combustion synthesis technique. The structural analysis is carried out using different analytical techniques such as Powder X-Ray Diffraction (PXRD), Fourier Transform InfraRed spectra (FTIR), Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM). The bandgap is found to be in the range 4.9–5.3 eV. Photoluminescence and cathodoluminescence spectra are studied for the investigation of the optical property of the synthesized nanoparticles. The pure rhombohedral phase is obtained after calcination at 900 °C. The agglomerated porous structure is revealed from SEM images of the nanoparticles. Under the 406 nm excitation wavelength and 10 keV accelerating voltage the PL and CL spectra are observed with characteristic emission peaks of Sm3+ ions from 4G5/2 to 6HJ=5/2,7/2,9/2 transitions with yellowish-orange color. The CIE coordinates confirm the emission of yellowish-orange luminescence from LaAlO3: Sm3+ phosphors. The results obtained reveal that these materials are potential candidates for the fabrication of field emission displays, photoluminescence liquid crystal displays, and other optical devices.