Minimum Color Research Articles

New method for the protection and restoration of calcareous cultural heritage stones by polyelectrolytes and hydroxyapatite nanocrystals

We have investigated the feasibility of a new two-step protocol for the restoration of marbles. The process employs a polyelectrolyte multilayer film that enhances the chemical affinity between the treated stone and restorative material (hydroxyapatite nanocrystals), through functionalization, while at the same time it attributes an acid resistant property to the resulting system. Surface functionalization and material deposition is achieved through spraying; a simple and versatile application method suitable for objects of various sizes and geometries. Polyelectrolyte (polyethylenimine and polyacrylic acid) deposition was examined through Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR-FTIR) and Atomic Force Microscopy (AFM), and tested through contact angle, water absorption and dissolution experiments. The hydroxyapatite nanocrystals were studied by ATR-FTIR, z-potential, AFM and Scanning Electron Microscopy (SEM), and characterized via contact angle and color alteration measurements. Our results show that the polyelectrolyte multilayer was stable in an aqueous environment with increased acid resistance (up to 46% decrease in mass weight loss when compared with untreated samples) and decreased water absorption (up to 39%). Color measurements of the outer hydroxyapatite layer showed a minimal color alteration for one type of the tested substrates showing low color difference values (ΔΕ* < 5). The results suggest that the proposed method holds great potential for marble restoration as it attributes multi-functionality and is easy to apply.

Evaluation of the Novel Dehydration Concept for Wild Multi Floral Honey in Vietnam

Dehydration of honey is an essential step during honey production in tropical countries to prevent rapid deterioration in quality because of the fermentation. In this study, honey dehydration at atmospheric pressure and temperatures of 36°C, 42°C, and 52°C in a pilot dehydration plant based on JEVA concept was carried out to reduce the moisture content of honey to below 17%. Honey dehydration at a temperature range of 36°C - 42°C achieved a high dehydration rate and low energy simultaneously due to integrating a heat pump into the processing loop. The temperature range of 36°C - 42°C was found out to be the most favourable processing temperature for honey dehydration since at these operational conditions, minimal colour degradation of honey, a low decline in diastase number and high retention of TPC and TFC (87.0% - 88.2% and 74.8% - 80.6%) were achieved. Moreover, honey samples dehydrated at 36°C and 42°C preserved antibacterial activity for strains of MRSE, Salmonella Typhimurium, Proteus Vulgaris, and Pseudomonas aeruginosa compared to raw honey. Under similar operational conditions, the proposed dehydration plant has been found to be better than that of other honey dehydrators reported in the literature in terms of dehydration rate, energy consumption, and lighter impacts on physiochemical characteristics.

Development and Verification of an Interspecific Hybridization Protocol for Asclepias

Milkweed (Asclepias sp.) is an important pollinator genus across North America and is a host plant for many butterfly species, notably the monarch butterfly (Danaus plexippus). Commercial production of Asclepias is limited to a few species, because most species lack commercial traits, with minimal branching habit, excessive height, and minimal color variation. This study used a commercially viable Asclepias species, butterfly weed (Asclepias tuberosa L.), as a maternal parent and trialed three different pollination methods in an attempt to create interspecific hybrids. Pollination methods included a traditional method, a pollen–solution-based method, and a novel inverted pollinia method. The inverted pollinia method increased pollination success rates 4-fold among intraspecific crosses of A. tuberosa. When pollination methods were optimized, A. tuberosa was used as the maternal parent, and one-way crosses were made to seven other Asclepias species using the inverted pollinia method. Of the seven species used as pollen donors, four developed hybrid seed successfully: green milkweed (Asclepias hirtella Woodson), purple milkweed (Asclepias purpurascens L.), showy milkweed (Asclepias speciosa Torr.), and common milkweed (Asclepias syriaca L.). As germination methods vary significantly among Asclepias species, three methods of germination were trialed on seed developed via interspecific hybridizations: direct seeded, cold–moist stratification, and embryo rescue. Of the three methods, cold–moist stratification was superior to direct seeding and embryo rescue. This research is the first documented case of a controlled interspecific hybridization event among these species.

Analisis Rainbow Vertex Connection pada Beberapa Graf Khusus dan Operasinya

Suppose $G=(V(G),E(G))$ is a non-trivial connected graph with edge coloring defined as $c:E(G) \rightarrow \{1,2,...,k\} ,k \in N$, with the condition that neighboring edges can be the same color. An original path is {\it rainbow path} if there are no two edges in the path of the same color. The graph $G$ is called rainbow connected if every two vertices in $G$ with rainbow path in $G$. The coloring here is called rainbow coloring, and the minimal coloring in a graph $G$ rainbow connection number is denoted by $rc(G)$. Suppose $G=(V(G),E(G))$ is a non-trivial connected graph with a vertex coloring defined as $c':V(G) \rightarrow \{1,2,...,k\},k \in N$, with the condition that neighboring interior vertex may have the same color. An original path is rainbow vertex path if there are no two vertices in the path of the same color. The graph $G$ is called rainbow vertex connected if every two vertices in $G$ with rainbow vertex path in $G$. The $G$ coloring is called rainbow vertex coloring, and the minimal coloring in a $G$ graph is called rainbow vertex connection number which is denoted by $rvc(G)$. This research produces rainbow vertex connection number on the graph resulting from the operation \emph{amal}($Bt_{m}$, $v$, $n$), $Wd_{3,m}$ $\Box$ $ P_n$, $P_m$ $\odot$ $Wd_{3,n}$, $Wd_{3,m}$ $+$ $C_n$, and \emph{shack}($Bt_{m}$, $v $, $n$).

Expanding the color gamut of inkjet textile printing during color matching

AbstractOne of the most important subjects of digital printing is evaluation of color gamut mapping. A printer can only reproduce colors that are in its color gamut. Maybe, a color tolerance between reference sample and printed sample is in agreement between manufacturer and customer. The goal of this work is to estimate the expansion of the color gamut of an inkjet textile printer by consideration of the acceptable (predetermined) color difference during color matching. For analyzing the color gamut, a standard color chart IT8.7/4‐2005 CMYK target was printed by nine different mixtures of CMYK, and then the reflectance spectra and colorimetric parameters of the printed samples were measured. The inks used were disperse water‐based inks that were printed on the polyester fabric. The maximum acceptable color difference in this study was equal to 2 CIELAB units for all colors. In order to estimate the color gamut with the maximum acceptable color difference, for all boundary points of gamut, expanded points were obtained by Euclidean distance less than = 2. The results show that when the acceptable color difference is considered in color gamut measuring, the area and volume of the color gamut are increased and so, the reproducibility of printer is increased. The maximum and minimum expansions of color gamut volumes were obtained by the mixtures with minimum and maximum color gamuts, respectively. The volume expansion of the mixture with the minimum color gamut volume was 34.20%, while the volume expansion of the mixture with the maximum color gamut volume was 28.06%.

Fusion of Multispectral and Panchromatic Images by Integrating Standard PCA with Rotated Wavelet Transform

Many pansharpening algorithms are based on the principle of extracting spatial details from panchromatic (PAN) images and injecting them into multispectral (MS) images. In this paper, we present two fusion approach based on same principle by integrating standard principle component analysis (PCA) with decimated and undecimated rotated wavelet transform. When decimated/subsampled rotated wavelet transform (SSRWT) is used for fusion of MS and PAN images, three visual artifacts get introduced in the fused image namely color distortion, shifting effect and shift distortion. To eliminate color distortion, SSRWT is integrated with standard PCA, i.e., PCA–SSRWT. Color distortion is significantly mitigated, but shifting effect and shift distortion persist in the fused image of PCA–SSRWT. After employing undecimated/nonsubsampled rotated wavelet transform (NSRWT), shifting effect and shift distortion get eliminated with minimum color distortion. However, fused image as a result of NSRWT is spectrally high but spatially low. In order to improve spatial quality and remove visual artifacts observed in SSRWT and PCA–SSRWT, NSRWT is integrated with standard PCA, i.e., PCA–NSRWT. Visual and quantitative analysis is carried out to validate the quality of fused image for all the algorithms. Visual interpretation suggests that fused image obtained using PCA–NSRWT is superior to fused images of SSRWT, PCA and NSRWT. The overall quantitative analysis manifests that the PCA–NSRWT is consistent with visual interpretation and performs better than state-of-the-art methods. PCA–NSRWT not only removes visual artifacts but also improves spectral and spatial quality of the fused image compared to individual PCA, SSRWT, NSRWT and PCA–SSRWT. Based on visual and quantitative analysis, it is observed that PCA works better with undecimated compared to decimated rotated wavelet transform for fusion.

Fast Single-Image Dehazing Algorithm Based on Piecewise Transformation in Optical Model

Single-image dehazing techniques are extensively used in outdoor optical image acquisition equipment. Most existing methods pay attention to use various priors to estimate scene transmission. In this paper, a fast single-image dehazing algorithm is proposed based on a piecewise transformation model between the minimum channels of the hazy image and the haze-free image in optical model. The minimum channel of the haze-free image is obtained by the piecewise transformation, which is a quadratic function model that we establish for the dark region, and a linear transformation model is established for the bright region. Using the minimum channels of the hazy image and the haze-free image, a transmission estimation model is established based on the haze optical model with adjustment variables. To obtain an accurate estimation of atmospheric light, we estimate the atmospheric light twice. Finally, the haze-free image is restored. Experimental results show that the proposed algorithm has minimal halo artifacts and color distortion in various depths of field, flat areas and sky areas. From the subjective evaluation, objective evaluation and running time analysis, it can be seen that the algorithm in this paper is superior to most existing technologies.

Color Changes in Some UV Irradiated Polymer Nanocomposite Materials for the Application in Textile Industry

Four nanocomposites (NCPs), e.g., polyaniline-copper/polymethyl methacrylate (PANI-Cu/PMMA), polyaniline-copper/cellulose triacetate (PANI-Cu/CTA), polyaniline-copper/polycarbonate (PANI-Cu/PC), and polyaniline-copper/polycarbonate-polyester (PANI-Cu/PC-PBT) were fabricated using both chemical oxidation and casting techniques. The morphology of the prepared NCPs was studied using scanning electron microscopy. The induced alterations in the color of the synthesized NCPs owing to UV irradiation, within fluences 25–120 J/cm2, have been illustrated via UV spectroscopy and CIE color divergence methodology. The color variation between the pristine and irradiated NCP samples (color intensity, ΔE) has been computed for the four NCPs. The results show that, upon UV irradiation up to 120 J/cm2, the values of ΔE for the PANI-Cu/PMMA NCP samples achieved a major color difference which is an acceptable match in commercial reproduction on printing presses since ΔE reached the value of 35.8. The value of ΔE for the PANI-Cu/CTA NCP samples reached 23.8 that also indicates a significant color difference. It is worth mentioning that the PANI-Cu/PC-PBT shows a minimum color difference since ΔE exhibited variation up to 7. This means that the PANI-Cu/PC-PBT NCP samples have higher resistance to color changes against UV radiation. Thus, this NCP may be a suitable candidate in textile industry.

Study on the effect of stepwise decreasing microwave power drying (SDMPD) of moth bean sprouts on its quality

AbstractVigna aconitifolia (Jacq.), locally known as moth bean, is a drought‐resistant pulse crop and grown in arid and semi‐arid areas of India. Green pods and grains, in cooked or sprouted form, are a mostly consumable part of the plant as they are rich in protein. Sprouting increases the bioavailability of protein by 30%, but bacterial contamination is high in sprouts due to its high initial moisture content that creates a problem for its storage. Hence, to rectify the said problem, drying the sprouts up to storable moisture level can be the best solution. The microwave drying was investigated for drying of sprouted moth beans. The microwave drying of sprouted moth beans using single microwave power was not suitable for drying, as the burning of the product takes place before reaching desired moisture content while dried at a microwave power of 900, 720, 540, and 360 W. During the drying at a microwave power of 180 W, it took about an hour for drying. However, during this drying, by the time it reaches moisture content at around 57.89 kg per 100 kg dm, the product shows browning. Therefore, a new technique was employed for drying sprouted moth beans, that is, Stepwise Decreasing Microwave Power Drying (SDMPD). The sprouts were dried at each microwave power level, in decreasing order for a particular time at each respective microwave power, to reduce the browning effect thus protecting the product from burning. The sprouted moth beans were dried in 19 min using SDMPD. The rehydration ratio was found to be 1.96. The moisture content of resultant dried sprouted moth beans was found to be 4.95 kg per 100 kg dm with a minimum color change (∆e*) of 10.46, which was found to be reduced up to 6.84 after rehydration, indicating the improved color.

Clarification of Byrsonima ligustrifolia Extract by Porous Membranes: Retention of Bioactive Compounds and Stability During Storage

Red-murici (Byrsonima ligustrifolia) extract, rich in bioactive compounds, was clarified by membrane processes for the first time. Permeate flux and bioactive compound retention were evaluated during crossflow filtration with α-alumina (MF-alumina) and polyetherimide (MF-PEI) microfiltration membranes and a polyethersulfone (UF-PES) ultrafiltration membrane. All membranes removed almost 100% of the initial turbidity (343 NTU). MF-PEI displayed the lowest retention of bioactive compounds (0.30–6.67%) and a permeate flux practically constant during 75 min of operation, even reaching a concentration factor above 10. Under the conditions evaluated (temperature of 25 °C, feed flow 150 L h−1 and transmembrane pressure of 0.02 MPa), the process was little affected by fouling, and the membrane was what offered the greatest resistance. Crude and clarified extracts suffered minimal color change and maintained more than 80% of anthocyanin content even after 60 days of storage at 4 °C, and in this condition, clarification increased the half-life of anthocyanins from 174 to 372 days. Higher temperatures (20 and 35 °C) and light exposure reduced the anthocyanins half-life by more than 80%. In summary, MF-PEI was able to produce a high-quality clarified red-murici extract that is maintained if stored at low temperatures and protected from light.

Stabilizing Hybrid Electrochromic Devices through Pairing Electrochromic Polymers with Minimally Color-Changing Ion-Storage Materials Having Closely Matched Electroactive Voltage Windows.

Conjugated electrochromic polymers hold great promises for next-generation color-changing windows and displays. One of the major roadblocks in their solid-state electrochromic devices is the relatively poor cycling stability. Finding ion-storage materials as a charge-balancing component is critical in improving their electrochemical cycling stability. A key criterion for the selection of ion-storage materials is to match their electroactive voltage windows with the paired electrochromic polymers. Thus, we developed a nanostructured, amorphous vanadium oxide (VOx) ion-storage material that exhibits high transmissivity, minimal color interference, and excellent charge-balancing capability in a closely matched electroactive window with the paired electrochromic polymers. High-performance magenta-to-transmissive hybrid electrochromic devices constructed from pairing the polymer with the VOx can be reversibly switched for 50 000 cycles with an optical loss less than 5%.

Optimization of the effect of accelerated weathering conditions on wood surfaces via the Taguchi method

This study investigated the effect of accelerated weathering conditions on total color changes on Scots pine (Pinus sylvestris L.) and poplar (Populus x euroamericana) wood surfaces using the Taguchi method. The experiments, based on the L18 orthogonal array, were conducted separately for both tree species. The radial and tangential surfaces of wood specimens were subjected to an accelerated weathering process using 340 nm ultraviolet (UV) lamps and temperature conditions of 50 °C. The factors for the minimum color change were determined via the signal-to-noise (S/N) ratios of the four parameters thought to be effective on color change. These parameters were cutting direction (two levels), UV-irradiance, conditioning, and water (three levels each). The most important factor affecting the color change was then determined by analysis of variance (ANOVA) testing. The results showed that the maximum UV-irradiance (W/m2) had the largest effect on the total color change, while the cutting direction (radial and tangential) had the smallest effect. The factors that affected the total color change of the poplar and Scots pine wood specimens were the same. However, the analysis revealed that different application times had varying effects on the color change.

Investigation of drying kinetics and qualities of turkey berry in fluidized bed dryer

In this work, drying kinetics, physical and bio-chemical properties of turkey berry were studied at an air velocity of 3.6 and 4.2 m/s along with different temperatures of 70, 80, 90 °C as well as open sun drying. The parameters such as drying rate, effective moisture diffusivity, activation energy, shrinkage, total color changes and Vitamin-C were analyzed in detail. The maximum moisture diffusivity of the sample was measured as 7.56 × 10−10 m2/s, at 90 °C with velocity of 4.2 m/s. The minimum and maximum activation energy was found as 30.79 and 32.29 kJ/mol at an inlet fluidized velocity of 3.6 and 4.2 m/s. The minimum volumetric shrinkage of the product was observed at 90 °C with velocity of 4.2 m/s while the minimum color change and maximum Vitamin-C retention was observed at 70 °C with velocity of 4.2 m/s. The morphology of the dried turkey berries was investigated using scanning electron microscope.

Color vision in civil aviation.

Color vision deficiency (CVD) is a condition that results in individuals being unable to distinguish differences between certain colors. Occupational color vision standards were introduced in aviation in 1919 by The Aeronautical Commission of the International Civil Air Navigation Authority. Concern has been expressed during the last few years that the current color vision standards in aviation may be too stringent and, at the same time, also variable across the world. The tests employed do not always reflect the tasks pilots encounter in today’s aviation environment. This ambiguity leads to the possible exclusion of deserving applicants for selection as aircrew. The compatibility of CVD with aircraft crew is assessed by medical personnel using clinical diagnosis tests on the ground level. These clinical tests were developed specifically to detect the presence, nature, and severity of CVD. No clinical tests yet provide a measure of operational performance in operating an aircraft. Arbitrary pass marks have been assigned to clinical tests such that a failing candidate will either be subject to operational restrictions or excluded completely. The prescribed clinical tests and associated pass marks vary considerably between regulators. While an individual may be subject to no restrictions in one jurisdiction, they may be excluded in another. This article highlights newer diagnostic techniques adopted by different countries for assessing color vision to see for the scope of evidence-based guidelines for minimum color vision requirements for flight crew as well as for civil aviation in India.

The Locating Chromatic Number of some Modified Path with Cycle having Locating Number Four

The locating-chromatic number was introduced by Chartrand in 2002. The locating-chromatic number of a graph is a combined concept between the coloring and partition dimension of a graph. The locating chromatic number of a graph G is defined as the cardinality of minimum color classes. In this paper, we discuss about the locating chromatic number of three types modified path with cycle having locating chromatic number four.

Colorimetric chemosensor for spermine based on pyrocatechol violet and anionic phenylboronic acid in aqueous solution

A new sensing method for colorimetric detection of spermine has been developed using a simple mixture of anionic pyrocatechol violet (PV) and 3-carboxyphenylboronic acid (CPB) in a neutral aqueous solution. In the absence of spermine, the boronate ester between PV and CPB formed to a small extent, resulting in slight spectral and insignificant color changes. The addition of spermine to the mixture caused solution color change from yellow to reddish-brown with a bathochromic shift in absorption spectra by the boronate ester formation between PV and CPB against the electrostatic repulsive interactions, while basic amino acids and other amines induced no or minimal color and spectral changes. The detection limit was determined to be 6.24 μM for spermine, which was within the critical concentration for cancer diagnosis. The mixture was demonstrated as a novel colorimetric chemosensor for spermine with high sensitivity and sensitivity. This present study can contribute to the facile method for colorimetric detection of cationic analytes by mixing anionic catechol dyes and similarly charged boronic derivatives.

Anti-caking Agent Effects on the Properties of Spray-dried ‘Cempedak’ Fruit Powder

‘Cempedak’ fruit, an aromatic fruit that has a short shelf life can be converted into powder through spray-drying process. However, the spray-dried powder that was obtained had a high tendency to cake. Hence, three different anti-caking agents (calcium silicate, silicon dioxide, and calcium phosphate) were added separately at a concentration of 1.5% (w/w). It was found that calcium phosphate (1.5% w/w) yielded ‘cempedak’ fruit powder with lowest moisture content, water activity, hygroscopicity, and caking (change in cake height ratio), with minimal color changes in its reconstituted form and low viscosity. Different calcium phosphate concentration (0-2.00% w/w) was then applied in the production of ‘spray-dried’ powder. With increase of calcium phosphate addition from 0 to 0.66%, the moisture content, water activity, hygroscopicity, cake height ratio of ‘cempedak’ powder decreased, with no significant decrease with further addition. Calcium phosphate (0.66 % w/w) yielded powder with the best properties: lowest moisture content (4.65%), water activity (0.18), hygroscopicity (22.0), and change in cake height ratio (0.17). In addition, there was a minimal change in color of its reconstituted powder, with a slight change in viscosity.

Sources of Variability in Vena Contracta Area Measurement for Tricuspid Regurgitation Severity Grading: Comparison of Technical Settings and Vendors

Previous studies found different cutoffs of vena contracta area (VCA) to define severe tricuspid regurgitation (TR). The aim of this study was to investigate the factors associated with such variability by comparing technical variables and vendors. Sixty-nine patients with scheduled tricuspid surgery were included in this prospective study. For each patient, TR data sets were obtained on three-dimensional color Doppler transthoracic echocardiography on at least two of three systems: GE Vivid E95 (n=39), Siemens SC2000 Prime (n=64), and Philips EPIQ 7C (n=60). VCA was measured using default settings or with color baseline shifted on all three platforms and with minimal color gain (10%-20%) on the GE platform. Color gain reduction and baseline shift caused significant change sin VCA measurement (-46% and 10%, respectively). Intervendor comparison exhibited wide limits of agreement (narrowest range, -74% to 167%), with either default or optimized settings. Different technical settings, platforms, and reference methods all produced different VCA cutoffs for severe TR. VCA measurement in TR is sensitive to technical factors and demonstrates intervendor variability. Technical variables in VCA measurement should be reported in detail to allow comparison among research studies. The same vendor and settings should be used for longitudinal analysis of TR VCA in the same patient in multivendor echocardiography laboratories.

Characterization of Color Differences for Color Palettes

Various color difference metrics were developed for characterizing the perceived color difference between individual color patches. Color difference between palettes containing multiple color patches, however, is critically important in product design and computer graphics. This study aimed to investigate how the perceived color difference between a pair of color palettes containing more than a single color patch is affected by the order and number of color patches in the palette. Two reference color sets were generated and each set had four color palettes containing 1, 4, 9, and 16 color patches that were arranged as 1 × 1, 2 × 2, 3 × 3, and 4 × 4 patterns. Human observers scaled the color differences between a color palette of the reference set and a color palette that had revised colors, or revised orders, or a combination of revised colors and orders compared to the reference palette. The calculated color differences between the two palettes were derived using the Minimum Color Difference Model (MICDM) algorithm proposed in a recent work with different color difference metrics, including CIELAB, CMC, CIE94, and DE2000. It was found that the perceived color differences of pairs of individual color patches were significantly larger than those containing multiple patches, when the calculated color differences were the same. The color differences metrics, except for CIE94, had similar performance when characterizing perceived color differences between color palettes.

Advanced polymerization system of photoinitiators in dental materials for aesthetic-functional restoration: case report

Introduction: In restorative dentistry, the faceting of teeth with aesthetic compromise is considered an effective procedure in which the clinician must choose the ideal treatment and select appropriate materials to obtain satisfactory and predictable aesthetic results. In this sense, the use of the Advanced Polymerization System (APS) has advantages, such as aesthetics, durability, degree of conversion and minimal color change. Objective: Demonstrate the aesthetic-functional restoration using adhesive system and composite resin with APS polymerization technology. Case report: A female patient attended the Integrated Clinic of the Faculty of Dentistry of UFRJ with a complaint of blackening of teeth related to ceramic laminates. After clinical and radiographic examination, it was decided to use composite resin veneers. Results: The composite resin veneers associated with the adhesive system promoted an excellent aesthetic result. Conclusion: The improvement of direct restorations with acid etching techniques and the use of new adhesive systems, combined with the constant development and scientific improvement of composite resins, enabled dentists to perform restorations in the most diverse clinical indications.