NEW ACID-BASIC INDICATORS: RESEARCH USING A SMARTPHONE

Modern cameras, desktop scanners, smartphones allow not only registering an image, but also determining its color characteristics. That allows us to quickly, objectively and automatically determine the color characteristics of colored samples in acid-base titration, because there is a significant error at visually determining the pH range of the color transition. In analytical chemistry the characteristics of acid-base indicators are very important, in particular their pH transition interval. But the disadvantage of most indicators is the wide range of color transition: from 1 to 3 pH units. The aim of this work is to find new acid-base indicators that change color in an alkaline environment and have a narrow pH range of the color transition. We have developed the apparatus and technique of convenient and highprecision simultaneous determination of the pH of the medium and the color of the acidbase indicators. In acid-base titration the PH measurements were performed with a combined glass electrode AD1131 by рН-meter AD1000. The color transition was determined with help of a smartphone with the subsequent processing of the results by computer software. The color characteristics were measured for each channel of the RGB model in the range from 0 to 255. Our apparatus is small and mobile, and allows us simultaneously to measure the pH of the medium and accurately to determine the color characteristics. As a result, we can construct graphical dependencies of color on pH for each channel of the RGB model. We found the N-arylsulfonyl-2-aroylamido-1,4-benzo(naphto)quinone monoimines and 2,5-dibenzoylamido-1,4-benzoquinone are good acid-base indicators. They “work” in the pH range from 8.82 to 11.35 and have a very narrow color transition interval from 0.10 to 0.61. Solutions of these compounds in an alkaline medium have bright intense colors due to formation of mesomeric ions. That allows using of these indicators in the titration of weak acids with strong bases and vice versa by the method of neutralization.

Morphometry of fruits, seeds and seedlings of Vitex megapotamica (Lamiaceae)

The present study evaluated the morphology and biometry of tarumã fruits and seeds. The experiment was conducted at the Federal University of Pelotas and the fruits were collected in two matrices located in Quedas do Iguaçu – Paraná, in March 2018. The length, width and thickness of fruits and seeds were determined using a digital caliper. For biometric assessments, the arithmetic mean, standard deviation, variation coefficient and the amplitude of the values obtained were calculated. The seed germination process started in approximately 32 days. Throughout the hypocotyl, a color transition was verified. It was observed that the values of length and width of the fruits varied from 15 to 22 mm and 12 to 18 mm, respectively. Regarding the biometry of the seeds, it can be verified that the length, width and thickness of the seeds varied from 5 to 13 mm, 4 to 10 mm and 3 to 7 mm, respectively. As for morphology, it was identified that the species has germination of the epigeal type with protected cotyledon seedlings (phanerocotyledons).

Transcriptional analysis reveals key insights into seasonal induced anthocyanin degradation and leaf color transition in purple tea (Camellia sinensis (L.) O. Kuntze)

Purple-tea, an anthocyanin rich cultivar has recently gained popularity due to its health benefits and captivating leaf appearance. However, the sustainability of purple pigmentation and anthocyanin content during production period is hampered by seasonal variation. To understand seasonal dependent anthocyanin pigmentation in purple tea, global transcriptional and anthocyanin profiling was carried out in tea shoots with two leaves and a bud harvested during in early (reddish purple: S1_RP), main (dark gray purple: S2_GP) and backend flush (moderately olive green: S3_G) seasons. Of the three seasons, maximum accumulation of total anthocyanin content was recorded in S2_GP, while least amount was recorded during S3_G. Reference based transcriptome assembly of 412 million quality reads resulted into 71,349 non-redundant transcripts with 6081 significant differentially expressed genes. Interestingly, key DEGs involved in anthocyanin biosynthesis [PAL, 4CL, F3H, DFR and UGT/UFGT], vacuolar trafficking [ABC, MATE and GST] transcriptional regulation [MYB, NAC, bHLH, WRKY and HMG] and Abscisic acid signaling pathway [PYL and PP2C] were significantly upregulated in S2_GP. Conversely, DEGs associated with anthocyanin degradation [Prx and lac], repressor TFs and key components of auxin and ethylene signaling pathways [ARF, AUX/IAA/SAUR, ETR, ERF, EBF1/2] exhibited significant upregulation in S3_G, correlating positively with reduced anthocyanin content and purple coloration. The present study for the first-time elucidated genome-wide transcriptional insights and hypothesized the involvement of anthocyanin biosynthesis activators/repressor and anthocyanin degrading genes via peroxidases and laccases during seasonal induced leaf color transition in purple tea. Futuristically, key candidate gene(s) identified here can be used for genetic engineering and molecular breeding of seasonal independent anthocyanin-rich tea cultivars.

Polyoxotungstate-based nanocomposite films with multi-color change and high volumetric capacitance toward electrochromic energy-storage applications

A facile fabrication strategy is proposed to construct a POMs-based nanocomposite film. It realizes multi-color transition during charging and discharging process, thereby links electrochromic behavior with energy storage performance.

Petal Color-Transition in Lonicera japonica is Mainly Associated with Increase of the Carotenoid Content and Carotenoid Biosynthetic Gene Expression

Background: Plants have remarkable diversity in petal color through the biosynthesis and accumulation of various pigments. To better understand the mechanisms regulating the petal pigmentation, we used multiple approaches to investigate the changes of carotenoids, gene expression dynamics and endogenous hormones in Lonicera japonica during petal color transitions, i.e. green bud petal (GB_Pe), white flower petal (WF_Pe) and yellow flower petal (YF_Pe). Results: Metabolome analysis showed that YF_Pe had a much higher content of carotenoids than white petals, with violaxanthin identified as the major carotenoid compound in YF_Pe. Comparative transcriptome analysis revealed that the key differentially expressed genes (DEGs) involved in carotenoid biosynthesis, such as phytoene synthase, phytoene desaturase and ζ-carotene desaturase, were significantly up-regulated in YF_Pe. However, expression levels of the carotenoid degradation-related genes, including abscisic-aldehyde oxidase 3 and carotenoid cleavage dioxygenase 4, were significantly down-regulated in YF_Pe. The results indicated that upregulated carotenoids concentrations and carotenoids biosynthesis-related genes promote the color transition. Furthermore, enrichment analysis of DEGs was mainly associated with the metabolic pathways of hormone signal transduction during petal color transitions. The DEGs were mainly involved in the auxin, cytokinin, gibberellin (GA), brassinosteroid (BR), jasmonic acid and abscisic acid (ABA) signal pathways. Accordingly, analyses of changes in indoleacetic acid, zeatin riboside, GA, BR, methyl jasmonate and ABA levels indicated that the color transitions are regulated by endogenous hormones. Conclusion: Our results provide new insight into the regulatory mechanisms underlying the petal color transitions during flower development process in L. japonica.

Polychromatic Coloring of Dental Zirconia by Inkjet Printing

To enable the development of an automated coloring process, dental zirconia is examined in terms of porosity, pore size and shrinkage during sintering. The properties of commercially available metal ionic inks such as viscosity, density and surface tension are investigated. Droplet impact on the zirconia surface and the absorption into the pores is analyzed with a high speed camera. The color result after sintering is investigated and compared to tooth samples. A method is developed to achieve a realistic, smooth color transition on flat zirconia samples. This is achieved by mixing the single inks directly on the zirconia through sequential application. Consequently, the number of different inks required to reproduce the full dental color scale can be reduced. Additionally, three dimensional tooth replacements are colored with the developed method.

The effect of 10,12-pentacosadiynoic acid on the morphology and characteristics of electrospun PDA/PU nanofibers

In this study, the effect of 10,12-pentacosadiynoic acid (PCDA) on the fabrication of PDA/PU nanofibers was examined. The PDA/PU nanofibers were prepared by electrospinning PU and PCDA at different mixing ratios, followed by photopolymerization. The viscosity and conductivity of the spinning solution and the morphology of the fabricated nanofibers were analyzed. We also examined the chemical structure changes, physical structure changes, and color transition characteristics of PDA/PU nanofibers. The concentrations of the spinning solutions and the mixing ratio of PCDA and PU had significant effects on the viscosity of the spinning solution and the diameter and shape of the nanofibers. The optimum conditions for economic efficiency and the practicality of the fabrication of a PDA/PU nano-fibers were 12–14 wt% spinning solution and a ratio of PU to PCDA of 4 to 1 or greater. For these conditions, the viscosity was in the range of 225–290 cP, which resulted in the production of smooth, uniform PDA/PU nanofibers without beads. The diameters of the nanofibers ranged from 270 to 550 nm. The results of FT-IR, XRD and DSC analyses confirmed that the PCDA were well mixed with the PU molecules and were electrospun. The fabricated PDA/PU nanofibers exhibited color transition phenomenon by external temperature stimulation above 70 °C.