Brilliant Yellow Color Research Articles

Preparation of Environmentally Friendly BiVO4@SiO2 Encapsulated Yellow Pigment with Remarkable Thermal and Chemical Stability

The preparation of environmentally friendly inorganic encapsulated pigments with a bright color and sufficient stability provides an effective strategy for expanding their applications in plastic, paint, glass, and ceramic decoration. The challenges facing the use of such pigments include the formation of a dense protective coating with the required endurance, the relatively weak color of the encapsulated pigments, and the preferable inclusion particle size. Environmentally friendly BiVO4 is regarded as a very promising pigment for multiple coloring applications due to its brilliant yellow color with high saturation. However, its poor thermal and chemical stability greatly limit the application of BiVO4. Herein, we report a sol–gel method to synthesize inorganic BiVO4@SiO2 yellow pigment with a core–shell structure. By controlling the synthesis conditions, including the particle size and dispersion of BiVO4 and the calcination temperature, a BiVO4@SiO2 encapsulated pigment with excellent chromatic properties was achieved. The obtained environmentally friendly BiVO4@SiO2 pigment with encapsulation modification has a comparable color-rendering performance to BiVO4, and it has a high thermal stability at 700 °C, excellent acid resistance, and good compatibility in plastics. The present research is expected to expand the application of yellow BiVO4 pigment in harsh environments.

A Yellow Lead-Free Pavement Marking Paint Based on Hybrid Dye-Clay Nanopigment: Morphological, Thermomechanical, and Photophysical Properties

This study utilized a yellow hybrid dye-clay nanopigment (DCNP) in a paint formulation to prepare a lead-free, eco-friendly pavement marking paint as an alternative to the conventional lead chromate (PbCrO4) paints. Two paint formulations based on DCNP and PbCrO4 were fabricated using a mechanical mixing method followed by sonication. The paint films were obtained via solution casting. The morphological property investigation demonstrated that the DCNP was well dispersed in the polymeric paint film with the formation of a partially intercalated/exfoliated structure. The film colored with DCNP showed a 75% improvement in storage modulus (E′), much higher than that of the film filled with PbCrO4 (39%). DCNP increased the glass transition temperature (Tg) of the paint by 5 °C, implying a favorable impact of this pigment on the pavement marking’s thermomechanical stability. The photophysical characterization revealed that the brilliant yellow color of the paint featured the yellow component value (+b*) of 69.9 units. Furthermore, the pavement marking standard colors were achieved with a considerably smaller amount of colorant when using DCNP due to its exceptional color strength. In conclusion, the remarkable functional properties of the nanopigment DCNP indicate its great potential as a promising alternative to lead chromate in pavement markings.

Uranium in the History of Medicine

Joachimsthal in Saxony was an important silver mining district since the Middle Ages when around the 1770s production started to decrease and the mining town was about to become a ghost town. It was at that time that Martin Heinrich Klaproth (1743-1817) a pharmacist in Berlin who became later professor of chemistry at the Royal Mining Academy, discovered that the black mineral in the ore can be used to give glass a brilliant yellow color with green fluorescence when added to the molten batch. He was also convinced that this mineral must have contained a new metal. This discovery coincided with the discovery in 1781 of a new planet in the solar system by his compatriot William Herschel who had immigrated to England in 1757 and called the planet Uranus. Hence Klaproth named the new metal “uranium” to honor his compatriot. In 1789 he was able to isolate a black heavy solid from the ore which he thought it to be the new metal. Since that time uranium started to play a dominant role in the history of medicine.

Casein phosphopeptide-metal salts combination: A novel route for imparting the durable flame retardancy to silk

Abstract The environmentally sound flame retardant (FR) treatment of textiles is the hot spot research in the processing of textiles. In this work, the combined treatment of casein phosphopeptide (CPP) and ferrous and titanium sulfates was applied to prepare the wash-resistant FR silk fabric. The complexation of CPP and metal ions was confirmed by Fourier transform infrared spectral analysis. The FR capability of the CPP and metal ions treated fabrics was demonstrated by two combustion methods. The fabrics obtained by treatment of 10 g/L CPP followed by mordanting of 4 g/L ferrous and titanium sulfates had a limiting oxygen index of 27.8% and 28.0%, respectively, and after vertical burning their residual char length was less than 15 cm even after 20 repeated washings. The increased thermal stability at high temperatures and good charring ability of the treated fabrics contributed to their FR capability. Interestingly, the CPP and ferrous sulfate treated fabric displayed a brilliant yellow color with good washing and rubbing fastness.

Characterization of enzymatic properties of two novel enzymes, 3,4-dihydroxyphenylacetate dioxygenase and 4-hydroxyphenylacetate 3-hydroxylase, from Sulfobacillus acidophilus TPY

BackgroundAs an environmental pollutant, 4-hydroxyphenylacetate (4-HPA) was a product of softwood lignin decomposition and was found in industrial effluents from olive oil production. Sulfobacillus acidophilus TPY was a moderately thermoacidophilic bacterium capable of degrading aromatic compounds including 4-HPA. The enzymes involved in the degradation of 4-HPA and the role of this strain in the bioremediation of marine pollutants need to be illustrated.Results3,4-dihydroxyphenylacetate dioxygenase (DHPAO) encoded by mhpB2 and two components of 4-hydroxydroxyphenylacetate (4-HPA) 3-hydroxylase encoded by hpaB and hpaC from S. acidophilus TPY, a moderately thermoacidophilic bacterium, involved in the degradation of 4-HPA possessed quite low amino acid sequence identity (22–53%) with other ever reported corresponding enzymes, which suggest their novelty. These two enzymes were expressed in E. coli and purified to homogeneity. DHPAO activity in E. coli was revealed by spraying with catechol or 3,4-dihydroxyphenylacetate (3,4-DHPA) on the colonies to make them turn brilliant yellow color. DHPAO possessed total activity of 7.81 U and 185.95 U/mg specific activity at the first minute when 3,4-DHPA was served as substrate. DHPAO was a thermophilic enzyme with optimum temperature of 50 °C and optimum substrate of 3,4-DHPA. The small component (HpaC) was a flavoprotein, and both HpaB and HpaC of 4-HPA 3-hydroxylase were NADH-dependent and essential in the conversion of 4-HPA to 3,4-DHPA. 4-HPA 3-hydroxylase possessed 3.59 U total activity and 27.37 U/mg specific activity at the first minute when enzymatic coupled assay with DHPAO was applied in the enzymatic determination.ConclusionsThe ability of this extreme environmental marine strain to degrade catechol and substituted catechols suggest its applications in the bioremediation of catechol and substituted catechols polluted marine environments.

Silver and gold nanoparticles as multi-chromatic lateral flow assay probes for the detection of food allergens.

In this study, we report the simultaneous use of gold and silver nanoparticles to set a multicolor multiplex lateral flow immunoassay (xLFIA). Silver nanoparticles (AgNPs), spherical in shape and characterized by a brilliant yellow color, were obtained by a new viable one-step synthetic protocol. AgNPs were stable over time and acceptably robust to conditions used for fabricating LFIA devices. These AgNPs were employed as a colorimetric probe in combination with two different kinds of gold nanoparticles (AuNPs) to set a visual xLFIA for detecting allergens. Surface plasmon resonance peaks of probes (AgNPs, spherical and desert rose-like AuNPs) were centered at 420, 525, and 620nm, respectively. Therefore, the xLFIA output was easily interpreted through a "yellow magenta cyan (YMC)" color code. The prospect of the YMC xLFIA was demonstrated by simultaneously detecting three major allergens in bakery products. Antibodies directed towards casein, ovalbumin, and hazelnut allergenic proteins were individually adsorbed onto metal nanoparticles to produce three differently colored specific probes. These were inserted in a LFIA comprising three lines, each responsive for one allergen. The trichromatic xLFIA was able to detect allergenic proteins at levels as low as 0.1mg/l and enabled the easy identification of the allergens in commercial biscuits based on the color of the probes. Graphical Abstract.

Color performance and near infrared reflectance property of novel yellow pigment based on Fe2TiO5 nanorods decorated mica composites

To obtain cool yellow pigments with high near-infrared reflectance, mica/Fe2TiO5 composite pigments were synthesized by a chemical liquid deposition method. The developed composite pigment powders were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis–NIR diffuse reflectance spectra, and CIEL*a*b* color scales. Different sized Fe2TiO5 nanorods were coated on the surface of mica particles. The particle size of the nanorods increased with increasing molar ratio of Fe3+ to Ti4+. The obtained composite pigments showed strong ultraviolet shielding ability and high near-infrared reflectance property. What's more, the Fe2TiO5 coating with smaller particle size possessed higher reflectance in the region of 700–1500 nm in accordance with the Kubelka-Munk theory. The near-infrared solar reflectance of mica/Fe2TiO5 composites was as high as 80.3%. An approximately 3 °C decrease in interior temperature was obtained for the heat box coated with the composite pigments. Furthermore, the composite pigments exhibit brilliant yellow colors. Therefore, mica/Fe2TiO5 composites are excellent near infrared reflective yellow pigments for efficient solar reflective coatings.

Novel environment-friendly yellow pigments based on praseodymium(III) tungstate

The novel environment-friendly inorganic yellow pigments, (Pr1-xCex)2W2O9+δ (0<x≤0.12) with the monoclinic structure, were synthesized and their color properties were investigated. The (Pr1-xCex)2W2O9+δ (0<x≤0.12) samples showed brilliant yellow color by doping trivalent Ce3+ into the Pr2W2O9 lattice due to the optical absorption in blue light region caused by the 4f-5d transition of Ce3+. According to the XPS and Rietveld analysis results, cerium ions in the crystal lattice have two different oxidation states of 3+ and 4+, in which the rate of each oxidation state is 58%:42%, and the Ce3+ and Ce4+ ions are preferentially occupied the PrO9 and the PrO8 polyhedral sites, respectively. Among the samples prepared, the (Pr0.90Ce0.10)2W2O9+δ pigment exhibited the most vivid yellow hue with high color durability for light and acid/base solutions.

Synthesis and optical properties of new highly NIR reflective inorganic pigments RE6Mo2O15 (RE = Tb, Dy, Ho, Er)

Novel near-infrared (NIR) reflecting pigments with colors ranging from yellow to orange to dark brown based on the rare earth molybdenum oxides RE6Mo2O15 (RE = Tb, Dy, Ho, Er) are described. The compounds were prepared by solid state reactions and characterized by XRD analysis and UV–Vis–NIR diffuse reflectance spectroscopy. The compounds RE6Mo2O15 (RE = Tb-Er) crystallize in a trigonal crystal structure with the cell parameters a = 737.6(2)–745.7(2) pm and c = 932.3(1)–946.4(1) pm. For the pigments Er6Mo2O15 and Ho6Mo2O15, optical and detailed color analysis revealed illuminant-dependent, color changing behavior (orange/yellow). Different light emitting sources such as classical bulb, LED, fluorescence lamp, and solar light were used for the characterization of these pigments. A brilliant yellow color hue was obtained for Dy6Mo2O15, whereas Tb6Mo2O15 exhibited a dark brown color. High NIR solar reflectance of 51.1%–98.1% were obtained for Tb6Mo2O15 and Ho6Mo2O15, respectively (recorded in the range between 700 and 2500 nm by using PTFE as reference).

Facile synthesis of NiTiO3 yellow nano-pigments with enhanced solar radiation reflection efficiency by an innovative one-step method at low temperature

Inorganic NiTiO3 nano-pigments have received recent attentions as possible candidates for cool materials to be used in building roofs and facades. In this paper, we have attempted to develop an innovative low temperature pathway (processed at 50 °C) for obtaining NiTiO3 nanocrystals by an ultrasound-assisted wet chemical processing method. Different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS) were used in order to characterize the size, morphology and optical responses of the obtained NiTiO3 nanoparticles. The crystallite size, particle size distribution range and band gap were found to be 10 nm, in the range of 10–20 nm and 3.72 eV, respectively. UV–Vis–NIR diffuse reflectance spectrum of NiTiO3 nanoparticles exhibited an intense reflection peak at around 580 nm, which is related to the brilliant yellow color of the synthesized nano-pigments. The enhanced reflectance seen in this work is much higher than that reported in similar works indicating these nano-pigments can be used as cool colorants for coating the building with better energy saving performance. Scanning electron microscopy studies indicated a uniform particle shape with a narrow size distribution. We believe that the methodology developed in this work provides a simple, cost-effective, and convenient route for synthesizing a variety of perovskite materials for assembling in nanotechnology.

Novel environmentally friendly inorganic yellow pigments based on gehlenite-type structure

The novel environmentally friendly inorganic yellow pigments, (Ca1−x−yEuxZny)2Al2SiO7+δ (0≤x≤0.15; 0≤y≤0.07) solids with the gehlenite-type structure, were synthesized and their color properties were investigated. The (Ca1−x−yEuxZny)2Al2SiO7+δ (0≤x≤0.15; 0≤y≤0.07) solids showed brilliant yellow color by doping divalent Eu2+ into the Ca2Al2SiO7 solid, and the yellowness of the pigment was enhanced by the co-doping of Zn2+ ion. Among the samples prepared, the (Ca0.87Eu0.10Zn0.03)2Al2SiO7+δ pigment exhibited the most vivid yellow hue with a yellowness value of b*=+75.8.

Crystal Structures of MBi2Br7 (M = Rb, Cs) – Filled Variants of AX7 Sphere Packing

AbstractThe reinvestigation of the pseudo‐binary systems MBr–BiBr3 (M = Rb, Cs) revealed two new phases with composition MBi2Br7. Both compounds are hygroscopic and show brilliant yellow color. The crystal structures were solved from X‐ray single crystal diffraction data. The isostructural compounds adopt a new structure type in the triclinic space group P$\bar{1}$. The lattice parameters are a = 755.68(3) pm, b = 952.56(3) pm, c = 1044.00(4) pm, α = 76.400(2)°, β = 84.590(2)°, γ = 76.652(2)° for RbBi2Br7 and a = 758.71(5) pm, b = 958.23(7) pm, c = 1060.24(7) pm, α = 76.194(3)°, β = 83.844(4)°, γ = 76.338(3)° for CsBi2Br7. The crystal structures consist of M+ cations in anticuboctahedral coordination by bromide ions and bromidobismuthate(III) layers 2∞[Bi2Br7]–. The 2D layers comprise pairs of BiBr6 octahedra sharing a common edge. The Bi2Br10 double octahedra are further connected by common vertices. The bismuth(III) atoms increase their mutual distance in the double octahedra by off‐centering so that the BiBr6 octahedra are distorted. The CsBi2Br7 type can be interpreted as a common hexagonal close sphere packing of M and Br atoms, in which 1/4 of the octahedral voids are filled by Bi atoms. The structure type was systematically analyzed and compared with alternative types of common packings. The existence of a compound with the suggested composition CsBiBr4 could not be verified experimentally.

Synthesis of Bi&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;&amp;ndash;Nb&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; solid solutions for environmental-friendly reddish yellow pigments

Bi2O3–Nb2O5 solid solutions were synthesized by conventional ceramic method and their color properties were investigated as environmental-friendly inorganic yellow pigments. Powder samples showed from light yellow color to brilliant reddish yellow color depending on their composition. The most brilliant reddish yellow color was obtained for 0.94Bi2O3–0.06Nb2O5 composition heated at 800°C for 30 min, which had color parameters (L*a*b*) of L* = 66.8, a* = 21.4, and b* = 63.6. The a*, b* values are comparable to that of commercial Cr2O3–Sb2O5–TiO2 based reddish yellow pigments. Since the present compounds are composed of nontoxic elements, it should be an attractive alternative to the conventional reddish yellow pigments.

Synthesis and Crystal Structure of Rutile‐type ScTa2O5N

AbstractA new phase in the system Sc‐Ta‐O‐N was synthesized by reaction of an amorphous oxide precursor with a gaseous NH3/O2 mixture at 800 °C. Crystal structure determination was performed using X‐ray powder data. ScTa2O5N crystallizes in the tetragonal space group P42/mnm (rutile‐type structure) and exhibits a brilliant yellow color (optical bandgap: 2.67 eV), making it a promising material for photocatalytical water splitting. Further investigation methods (SEM, TEM, and N2‐physisorption) were applied for more detailed characterization of the new phase. Unfortunately, the new compound could not be prepared as pure phase. So far a phase purity of ca. 90 % was the best result.

The hormonal regulation of color changes in the sexually dichromatic frog Buergeria robusta.

During the breeding season, dynamic changes in body coloration are regularly observed in the male brown tree frog Buergeria robusta. This study investigated the hypothesis that this sexual dichromatism in male B. robusta is mediated through hormonal regulation. Frogs were exogenously injected with testosterone (T) or estradiol (E2). This manipulation revealed that the body coloration (hue, brightness, and saturation) of the male frog increased significantly (i.e., the brilliant yellow color developed) in response to T but not in response to E2. Concurrently, the levels of expression of brain-derived neurotrophic factor (BDNF) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the pituitary gland were reduced in frogs whose coloration was pale brown on a yellow background. In particular, the weakest expressions of BDNF, PACAP, and PACAP type II receptors (VPAC-1R) were found in male frogs with a brilliant yellow body color during the breeding season regardless of background color. These changes may decrease α-melanocyte-stimulating hormone production associated with the PACAP receptors (VPAC-1R), resulting in the aggregation of black pigment in melanophores and the production of a brilliant yellow body color. The effects of hormones on skin coloration were further examined in isolated skin in vitro. The results of this investigation showed that the dispersion of xanthophores was stimulated by T or prolactin (PRL) and that the melanophores were aggregated by melatonin (MEL) but not by E2. Furthermore, yellow pigments in the xanthophores were significantly dispersed following the PRL+T treatment. In the T+MEL, PRL+MEL, and T+PRL+MEL treatments, xanthophores were dispersed, and melanophores were aggregated and subsequently moved to the low spongiosum layer of the dorsal skin, causing the increase in yellow coloration. These results reveal that multiple hormones play major roles in the regulation of the brilliant yellow coloration of male B. robusta by high plasma T during the breeding season.

Role of curcuma longa in health: A review

Turmeric is a plant that has a very long history of medicinal use, dating back nearly 4000 years. In Southeast Asia, turmeric is used not only as a principal spice but also as a component in religious ceremonies. Because of its brilliant yellow color, turmeric is also known as Indian Saffron. Periodontal disease affects approximately 75 percent of adults over age 30. The leading cause of tooth loss, periodontal disease begins with an accumulation of plaque- a sticky deposit of mucus, food particles and bacteria that adheres to the teeth. Turmeric relieves pain and inflammation linked with gingival disease. The objective of this article is to highlight uses of turmeric in the reduction of periodontal disease.

Novel and environmentally friendly (Bi,Ca,Zn)VO4 yellow pigments

Bi1−x−yCaxZnyVO4−(x+y)/2 (0 ≤ x ≤ 0.10, 0 ≤ y ≤ 0.10) pigments were synthesized as novel inorganic yellow pigments that are environmentally friendly, and their color properties were characterized. The Bi1−x−yCax–ZnyVO4−(x+y)/2 pigments exhibited brilliant yellow colors, and using the CIE L*a*b* system, the most vivid yellow hue was obtained for Bi0.90Ca0.08Zn0.02VO3.95 with a yellowness value (b*) that is larger than that of a commercially available bismuth vanadate yellow pigment. BiVO4 is an environmentally friendly inorganic yellow pigment, and Ca and Zn are also nontoxic elements; therefore, the Bi0.90Ca0.08Zn0.02VO3.95 pigment should be an effective alternative to conventional toxic yellow pigments.

Potential NIR Reflecting Yellow Pigments in (BiV)1−x(YNb)xO4 Solid Solutions

Abstract New yellow inorganic pigments, (BiV)1−x(YNb)xO4 with high NIR reflectance were synthesized by a conventional solid-state reaction method. The effect of isovalent dopants, namely, Y3+ and Nb5+ on BiVO4 samples was characterized using powder X-ray diffractometer, scanning electron microscope, UV–vis–NIR diffuse reflectance spectrometer, and CIE 1976 L*a*b* color scales. The prepared pigments exhibit brilliant yellow colors with significant enhancement of NIR reflectance to 90.8% when compared to undoped BiVO4 at the 1100 nm range. Further, the solid solutions allow fine tuning of the band gap displaying various yellow colors. The lattice distortion and reduction in particle size are responsible for the enhancement of the pigment characteristics. The above results indicate that these yellow pigments have potential to be used as cool colorants for roofs and automotives as energy-saving coatings.

Brilliant yellow color and enhanced NIR reflectance of monoclinic BiVO4 through distortion in VO43− tetrahedra

Bright yellow coloration and enhanced NIR reflectance of monoclinic bismuth vanadate are obtained by the substitution of Ta/P into the vanadium sites of BiVO4. Pentavalent metal ion substitution in bismuth vanadate blue shifted the absorption edge leading to bright yellow coloration and the color properties are comparable to that of commercially used praseodymium yellow. Lattice distortion and reduced crystallite size imposed by pentavalent metal ion substitution are responsible for the special optical properties. The synthesized pigments with improved yellow coloration exhibits good NIR reflectance making them potential candidate for cool colorants to reduce the heat build-up.

I DRONI PER L’AGRICOLTURA

New trends in precision farming show the deployment of different types of technology among which Infrared photography is becoming progressively relevant. Thanks to the special op tical behavior shown by plants in the band of infrared radiation, it is po ssible to measure indexes from infrared photos -such as NDVI (Normalized Difference Vegetation Index)-able to assess the health status of a crop . These photos, depicting vegetation in brilliant red, yellow and other colors can detect problems such as lack of nutrients, infection of parasites or water stress. Following this technology evolution, different types of cameras have becom e available with a low weight and an affordable cost to be used on small, unmanned aerial vehicles. Salt & Lemon is carrying out various experimental activities along with academic bod ies, research centers and agronom ists in order to exploit drones features in agriculture refining the techniques for capturing and analyzing data to provide farmers with the most useful health assessment of their crop s.