Comparative study of photosynthetic pigments in the leaves of forage plants of the cryolithozone of Yakutia

Thin-layer chromatography and spectrophotometry were used to determine the content of photosynthetic pigments (chlorophylls a and b, carotenoids) in green leaves of forage plants. It was found that the content of carotenoids was high for forage grasses with a high content of green pigments. It was revealed that β-carotene plays the most important role since it is a precursor of vitamin A and lutein, which has a high antioxidant (protective) property. According to modern concepts, lutein and β-carotene actively function in various organs of herbivores. They play a special role in the functioning of the mammalian visual apparatus, protecting this organ from the light factor. In addition, lutein is one of the physiologically active substances that make up cow’s milk.

The impact of the mulberry (Morus nigra L.) leaf extract on the physicochemical properties of poly(vinyl alcohol) blend films

In this work, mulberry (Morus nigra L.) leaf extract was added in poly(vinyl alcohol) (PVA)-based films and its impact on the film’s properties was evaluated. In addition, HCl and glycerol were studied for their use as additives to prepare PVA-based films. The results showed that HCl and glycerol have minimal impacts on the films’ appearance, while mulberry leaf extract imparted green colour to the films produced, mainly due to the presence of green pigments. Moreover, the results suggested that a significant interaction has occurred between the polymer matrix and leaf extract, contributing to a more compact and uniform film morphology. The tensile strengths of the films increased from 21.38 to 28.28 MPa after the addition of mulberry leaf extract. Additionally, the films were tested for their application as food wrapping films. Overall, the results showed that PVA-based films incorporated with mulberry leaf extract have higher capability to preserve the freshness of food when compared to commercial cling wraps from brands such as Diamond and Glad. Appropriate proportions of additives (mulberry leaf extract, HCl and glycerol) used in the formulation of P-GH-M20 films showed improvement in its mechanical properties and food preservation capability.

A Multi-Analytical Study of Egyptian Funerary Artifacts from Three Portuguese Museum Collections

A diachronic, multi-analytical approach combining EDXRF, µFTIR, µRaman, SEM-EDS, and Py-GC/MS has been adopted with the aim to study for the first time the painting materials used to decorate Egyptian funerary masks and sarcophagi ranging from the Late Period to the Roman Period and stored in the Archaeological National Museum (MNA) and the Carmo Archaeological Museum (MAC) of Lisbon and the Natural History Museum of the University in Oporto (MNH-FCUP). Results indicate that yellow and red ochres, realgar, cinnabar, Egyptian blue, and Egyptian green were used as pigments while chalk served as the preparatory layer. Over the 1000-year timeline of the studied artifacts, the palette remained remarkably consistent with previous findings as exemplified by cinnabar being used for red pigments in samples only dated after the Ptolemaic period. The presence of Sn in Egyptian blue and Egyptian green pigments used in one sample suggests the use of recycled bronze scraps during pigment production. Black pigments in two Late Period masks were found to be produced by mixing Egyptian blue with red ochre suggesting either a hitherto unknown method for production of purple pigments in the Egyptian palette or, alternatively, an attempt to create a specific hue or shade of dark brown or black. The results of this study contribute to further expand the database of Ancient Egyptian painting materials while at the same time helping to valorize three important Egyptian collections in Portugal.

Impact of NaCl on physiological and biochemical characteristics of maize (Zea mays L.) plants

Aim. The effect of 50 and 100 mmol NaCl concentrations on seed germination, the content of green pigments in seedlings, and on the activity of photosystem II in seedlings of maize varieties Zagatala 420, Zagatala 514, Zagatala 68 and Gurur and hybrid Gurur x Zagatala 68 was studied. Methods. Plant seeds were germinated under laboratory conditions in Petri dishes and pots with soil using 50 and 100 mmol of sodium chloride solutions. Germination, seed germination energy had been determined. In two-week old seedlings determined the number of photosynthetic pigments and the activity of photosystem II. Results. High concentrations (100 mmol) of NaCl reduced seed germination, pigments number, and photosystem II activity. At a salt concentration of 100 mmol, an increase in the carbohydrate content was noted. Conclusions. Varieties Gurur and Zagatala 68 and hybrid Gurur x Zagatala 68 were more tolerant compared to varieties Zagatala 420, Zagatala 514. Keywords: maize, NaCl, photosynthetic pigments, photosystem II.

Glucose Induces Thylakoid Formation and Upregulates Green Pigment Contents in Complete Dark Culture of the Angiosperm Pachiramacrocarpa

In addition to angiosperms, most plants are able to synthesize chlorophyll (Chl)-generating green tissues in total darkness. In this study, 140 plants of the angiosperm Pachira macrocarpa were divided into five groups. Among them, one group was grown for 2 weeks under natural light conditions, whereas the others were grown in complete darkness (0 μmol m−2 s−1). Dark-grown plants were then treated with 0~6% glucose for another 8 weeks. The budding and greening ratios, ultrastructure of chloroplasts (ChlPs) of newly developed leaves, and green pigment contents of pre-illuminated mature and young leaves, and totally dark-grown newly developed leaves were measured. Results showed that glucose inhibited the budding and promoted the greening of newly developed leaves. Pre-illuminated mature and young leaves were able to synthesize green pigments during the 2 weeks of dark adaption. Dark-grown newly developed leaves contained high levels of green pigments at 2 and 3 weeks after budding. Green pigments of glucose-fed newly developed leaves had increased, whereas they had decreased in control leaves. In addition, ChlPs of dark-grown glucose-fed newly developed leaves contained both giant grana and prolamellar bodies (PLBs), usually found in shade plants and etiolated seedlings, respectively. The higher the glucose concentration was, the greater the numbers of grana, thylakoids, and PLBs. Glucose increased the green pigment contents and grana formation in newly developed leaves in a dark condition, and the mechanisms are discussed.

Crystal structure of copper perchlorophthalocyanine analysed by 3D electron diffraction

Copper perchlorophthalocyanine (CuPcCl16, CuC32N8Cl16, Pigment Green 7) is one of the commercially most important green pigments. The compound is a nanocrystalline fully insoluble powder. Its crystal structure was first addressed by electron diffraction in 1972 [Uyeda et al. (1972). J. Appl. Phys. 43, 5181–5189]. Despite the commercial importance of the compound, the crystal structure remained undetermined until now. Using a special vacuum sublimation technique, micron-sized crystals could be obtained. Three-dimensional electron diffraction (3D ED) data were collected in two ways: (i) in static geometry using a combined stage-tilt/beam-tilt collection scheme and (ii) in continuous rotation mode. Both types of data allowed the crystal structure to be solved by direct methods. The structure was refined kinematically with anisotropic displacement parameters for all atoms. Due to the pronounced crystal mosaicity, a dynamic refinement was not feasible. The unit-cell parameters were verified by Rietveld refinement from powder X-ray diffraction data. The crystal structure was validated by many-body dispersion density functional theory (DFT) calculations. CuPcCl16 crystallizes in the space group C2/m (Z = 2), with the molecules arranged in layers. The structure agrees with that proposed in 1972.

Metal complex pigments

There are several commercially significant metal complex organic pigments that are based on first row transition metals. The most important of these are the copper phthalocyanine blue and green pigments which find virtually universal use in paints, printing inks, and plastics. These pigments are of such prime importance that they are dealt with separately in three other chapters in this series. This paper describes a group of pigments that are complexes of iron, copper, nickel, and cobalt with polydentate colored ligands of azo, azomethine, oxime, and isoindoline chemical types. The oldest metal complex organic pigment that still finds some use is CI Pigment Green 8, an octahedral oxime iron complex. In the 1970s and 1980s, there was considerable industrial research effort aimed at developing metal complex pigments based on azomethine and isoindoline structures, many of which were found to offer excellent lightfastness, good solvent resistance and thermal stability, although they exhibited rather dull colors. However, several products provide brilliant effects when used in combination with metallic and pearlescent pigments in automotive paints. Many of the pigments introduced have since been withdrawn by the original manufacturers, but a few remain on the market. The synthesis of metal complex pigments generally involves the preparation of the colored ligand, which is then complexed with the transition metal ion

Phthalocyanine green pigments

The dominant organic green pigments are polyhalogenated copper phthalocyanines (CuPcs). These pigments exhibit similar excellent coloristic and technical performance to CuPc blue pigments and are produced worldwide in large quantities. The green pigments are halogenated CuPcs. There are two pigments with CI designations. CI Pigment Green 7 is a bluish green product, in which the 16 ring hydrogen atoms of the CuPc molecule are replaced virtually completely by chlorine. Products designated as CI Pigment Green 36 incorporate a range of bromo- and bromochlorocopper phthalocyanines and are yellowish-green pigments. CuPc green pigments are manufactured by direct exhaustive halogenation of crude CuPc blue with chlorine or bromine or an appropriate mixture of the two halogens, depending on the composition of the product required. The synthesis is carried out at elevated temperatures in a suitable solvent, commonly a molten AlCl3/NaCl eutectic mixture.

Chromium oxide pigments

The chromium(III) oxide pigments Cr2O3 (chromium oxide green) and CrOOH (chromium oxide hydrate green) are representatives of the inorganic green and blue–green pigments. Cr2O3 pigments are very important for the coloration of paints, coatings, plastics, building materials and other application systems. CrOOH pigments have lost their technical importance because of the low thermal stability. Chromium oxide green pigments are characterized by excellent application properties. They are synthesized starting from alkali dichromates or ammonium dichromate by reduction in liquid or solid phase.