Study the fluorescent and conductivity properties of a 4-hydroxy-3-nitro-1,8-naphthalic anhydride

The compound of (4-hydroxy-3-nitro-1,8-naphthalic anhydride) and the dopant material (4-hydroxy-m-benzene-disulfonic acid) were synthesized. The UV-Vis absorption and fluorescence spectra of the compound were recorded. The bathochromic shifts in absorption due to the changes in the solvent polarity was observed, in DMSO solvent, the compound shows different peaks, three bands in the UV region and one band in the visible region, one absorption peak at 402 nm, which might be attributed to the (ICT) band. The emission spectra of this compound were sensitive to the solvent polarity. They moved to lower energies with increasing the polarity of the solvent. The influence of the solvent polarity on the fluorescence maximum was more pronounced compared with the absorption maximum, showing ca. 3 nm red shift on moving from butanol to DMSO. The effect of the dopant material on the conductivities (ionic and specific) of the compound was studied, the ionic conductivity was increased as the weight of the dopant material increases, and the ionic conductivity (G) was measured in water as a solvent. the (G) of the compound was 2.4X10-6 Siemens at 0.01 gm of the dopant material, and was 2.62X10-4 Siemens after the dopant material was added (0.1 gm).

Matching Effects in the Interaction of Ionic Surfactants with Fluorescent Reagents in Micellar Solutions of Triton X-100

The influence of cationic and anionic surfactant solutions on the character of the fluorescence spectra of reagents of different charge and hydrophobicity in aqueous solutions of nonionic surfactant Triton X-100 has been studied. An increase in the fluorescence intensity and a shift in the position of the fluorescence maximum with increasing hydrophobicity of reagents and ionic surfactants have been shown. The analytical signal of the surfactant is further amplified in the proximity of the charge values of the reagent and the counterion of the surfactant. The non-monotonic nature of the hydrophobicity effect of cationic surfactants on their analytical signal in the system has been shown. The observed effects are explained by the realization of charge and hydrophobic matching in the interaction of surfactants with the fluorescent reagents. The obtained effects are significant in the design of fluorescent systems for the determination and study of surfactant micelles. Conditions for detecting the content of cetylpyridinium chloride by reaction with eosin Y and sodium tetradecyl sulfate by reaction with rhodamine 6G in the presence of Triton X-100 were proposed. The methods have been tested in detecting the content of the ionic surfactants in pharmaceuticals.

Morphophysiology of ornamental sunflower plant irrigated with saline water and application of silicon

The use of saline water in agriculture is an alternative, especially in regions with water scarcity, such as the Brazilian Northeast semiarid. However, salt stress considerably reduces plant growth and development. In this sense, the objective was to evaluate the morphophysiological responses of the ornamental sunflower irrigated with saline water under application of silicon. The experimental design was entirely randomized conducted in a factorial 4 x 5 with 6 replicates, related to four electrical conductivity of the irrigation water (ECw): 0.5; 1.5; 2.5 and 3.5 dS m-1 five silicon rates: 0, 50, 100, 150 and 200 mg L-1, proceeding to the evaluation of: plant height, stem diameter, number of leaves, absolute and relative growth rates, initial fluorescence, maximum fluorescence, variable fluorescence, maximum efficiency of the photochemical process in FSII, potential quantum yield of photosystem II, stomatal conductance and instant efficiency in the use of water. The gradual increase of ECw reduces growth, chlorophyll fluorescence a and stomatal opening of the ornamental sunflower plants. The application of silicon above 100 mg L-1 promotes a decrease in ornamental sunflower stomatal conductance. It is recommended to irrigate ornamental sunflower plants with water of 0.5 dS m-1 associated with the application of 100 mg L-1 of silicon.

Variation in cold tolerance in F6 durum wheat [Triticum turgidum (L.) Tell. convar. durum (Desf.) Mackey] RILs and the relationships of cold tolerance with some quality parameters and genetic markers

Low temperature is one of the critical factors for determining agricultural production. Therefore, the main objective was to develop the durum wheat lines, which are tolerant to cold particularly in Central Anatolia. The recombinant inbred lines (RILs) (141) derived from F6 progeny of durum wheat, developed from Kunduru-1149 (female parent) and Cham-1 (male parent) cross, were characterized in terms of their cold tolerance both in the field and under controlled (in growth chamber) conditions. A 0–9 scale was used for the visual evaluation of cold damage under field conditions, and a quantitative measure of photochemical efficiency (Fv/Fm = variable fluorescence/maximum fluorescence) method was used for the evaluation of cold damage under controlled conditions. Seventeen RILs displayed the scores within the range of 1–2.5 in 0–9 scale evaluation, while 41 RILs showed the scores equal to or higher than 0.70 approaching to optimal (~0.83) in Fv/Fm evaluation. Some quality parameters tested and some gliadin fragments and random amplified polymorphic DNA loci showed meaningful correlations with the data of 0–9 scale and Fv/Fm ratios from lower to the medium level. The RILs considered as cold resistant; might have the potential to be used as parental lines to develop cold-resistant durum wheat varieties in the future durum wheat-breeding programmes.

PYRACLOSTROBIN PRESERVES PHOTOSYNTHESIS IN ARABICA COFFEE PLANTS SUBJECTED TO WATER DEFICIT

The objective of this study was to investigate the effect of pyraclostrobin on the photosynthetic performance of rabica coffee plants subjected or not to a water deficit, using the parameter of gas exchange (net CO2 assimilation, stomatal conductance, transpiration rate, and internal CO2 concentration and nocturnal respiration), chlorophyll fluorescence a parameters (minimum fluorescence, maximum fluorescence, maximum quantum yield of photosystem II, effective quantum yield of PSII, quantum yield of regulated energy dissipation and quantum yield dissipation non-regulated) as well as the concentrations of chloroplast pigments. In the plants maintained without water deficit, pyraclostrobin did not cause any alteration on the parameters of chlorophyll a fluorescence; however, it contributed to an increase in the level of chlorophyll a + b, CO2 assimilation and CO2 influx for the carboxylation sites of the stroma. Decreases in nocturnal respiration in plants treated with pyraclostrobin, submitted or not to water deficit seems to be a common strategy in reducing energy waste in the maintenance metabolism. Under water deficit, pyraclostrobin contributed to increase the photochemical yield, enabling plants to effectively prevent the capture, use and dissipation of light energy.

Fluorescent properties of surface tissues of apples of different varieties in the green area of spectrum

Background: Traditional methods of the content and composition of fruits nutrients determining are labor-intensive and material-intensive, require grinding and special processing of biological material. The fluorescent method is one of the most modern and promising. It allows determining physiological and metabolic parameters without plant tissues destruction. Therefore, the patterns and causes of differences identification of the different apple varieties fluorescent properties is an important task, which will solve the problem of non-invasive determination of the composition and content of useful substances in fruits. Objectives: The determination of the surface tissues fluorescent properties in the green area of the fluorescence spectrum of apple varieties with different coloring of exocarp is the purpose of the work. Materials and methods: The object of the study is apples of four popular winter varieties, close in maturity, with different coloring of exocarp. The method of fluorescence spectroscopy of the apples surface tissues was used. The excitation was made by a semiconductor laser with a wavelength of 405 nm and a power of 36 mW, operating in a continuous mode. The apples coloring is defined as the coordinate a of the CIELAB color mapping system. Results: It was found that the wavelength of the maximum in the green area of the fluorescence spectrum of different apple varieties surface tissues differs by approximately 8–18 nm. At the same time, the difference of wavelengths of the maximum in the red area for different apple varieties does not exceed 5 nm. It was found that wavelength of the maximum in the green area of the fluorescence spectrum differs in different varieties in accordance with the coloring of the exocarp. If green color prevails in the exocarp coloring the fluorescence maximum in the green area has a longer wavelength, and if red prevails it has a shorter wavelength, while if yellow prevails, the wavelength occupies an intermediate position. Conclusions: The pigment composition of the surface tissues of apples affects on their fluorescence in the green area of the spectrum. Possible reasons for the differences of the maximum wavelength in the green area of the fluorescence spectrum are the variability of flavonols composition depending on the apple variety and the influence of red pigments.

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

The permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA) in 600 nm thin films on a glass support was probed by the energy of the charge transfer transition in the oxazine dye Nile red (NR) at 25 °C. The absorption and fluorescence spectra of NR were observed to shift to the red with increasing solvent polarity, because of the intramolecular charge transfer character of the optical transition. New types of solvatochromic plots of emission frequency against absorption frequency and vice versa afforded the Onsager radius-free estimation of the ground and excited states dipole moment ratio. With this approach the values of these dipole moments of 11.97 D and 18.30–19.16 D, respectively, were obtained for NR. An effective local dielectric constant of 5.9–8.3 for PMMA thin films was calculated from the solvatochromic plot and the fluorescence maximum of NR observed in the PMMA films. The fluorescence band of NR in the rigid PMMA films shifted to the red by 130 cm−1 with increasing excitation wavelength from 470 to 540 nm, while in a series of liquids the position of the emission maximum of NR remained constant within same range of the excitation wavelength. It is concluded that the fluorescence spectrum of NR in PMMA undergoes inhomogeneous broadening due to different surroundings of NR molecules in the ground state and slow sub-glass transition (T g) relaxations in PMMA.

SUBSTRATE AND FERTILIZATION IN THE QUALITY OF Myrocarpus frondosus SEEDLINGS

Myrocarpus frondosus is a native species with high commercial timber value. Thus, the objective of this research was to evaluate the quality of seedlings of Myrocarpus frondosus in the nursery and to indicate the most adequate substrate and fertilization for the production of seedlings. The experiment was conducted in a completely randomized design, with four replications, in a factorial scheme, composed of four combinations of substrates: S1-100% commercial substrate (CS); S2 - 80% CS and 20% carbonated rice husk (CRH); S3 - 60% CS and 40% CRH; S4 - 40% CS and 60% CRH, and four fertilizations: NF – No fertilization; CRF – controlled release fertilizer (ammonium sulfate, simple superphosphate and potassium chloride); RRF – ready release fertilizer and micronutrients. Physical and chemical analyses were performed on the substrate. At 300 days after emergence, the following morphological variables were evaluated: (height, stem diameter, H/SD ratio, leaf area, root length, aerial dry mass, root dry mass, total dry mass, Dickson quality index) and the physiological variables chlorophyll a, chlorophyll b, carotenoids, initial fluorescence, maximum fluorescence, Fv/Fm ratio and electron transport rate). Regardless of the substrate and fertilization, slow growth of the species was observed, even for the best treatment, which was verified from the height (17.87 cm) and stem diameter (2.62 mm). The use of the commercial substrate (40%) with carbonated rice husk (60%) associated with the concentration of 6 g L-1 of controlled release fertilizer is recommended, since they present the best results for the morphological and physiological variables in the nursery in general.

Synthesis, photophysical and electrochemical properties of pyridine, pyrazine and triazine-based (D–π–)2A fluorescent dyes

The donor–acceptor–π-conjugated (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 with two (diphenylamino)carbazole thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and a pyridine, pyrazine or triazine ring as electron-withdrawing group (electron-accepting group, A) have been designed and synthesized. The photophysical and electrochemical properties of the three dyes were investigated by photoabsorption and fluorescence spectroscopy, Lippert–Mataga plots, cyclic voltammetry and density functional theory calculations. The photoabsorption maximum (λmax,abs) and the fluorescence maximum (λmax,fl) for the intramolecular charge-transfer characteristic band of the (D–π–)2A fluorescent dyes show bathochromic shifts in the order of OUY-2 < OUK-2 < OUJ-2. Moreover, the photoabsorption bands of the (D–π–)2A fluorescent dyes are nearly independent of solvent polarity, while the fluorescence bands showed bathochromic shifts with increasing solvent polarity (i.e., positive fluorescence solvatochromism). The Lippert–Mataga plots for OUY-2, OUK-2 and OUJ-2 indicate that the Δμ (= μe − μg) value, which is the difference in the dipole moment of the dye between the excited (μe) and the ground (μg) states, increases in the order of OUY-2 < OUK-2 < OUJ-2. Therefore, the fact explains our findings that OUJ-2 shows large bathochromic shifts of the fluorescence maxima in polar solvents, as well as the Stokes shift values of OUJ-2 in polar solvents are much larger than those in nonpolar solvents. The cyclic voltammetry of OUY-2, OUK-2 and OUJ-2 demonstrated that there is little difference in the HOMO energy level among the three dyes, but the LUMO energy levels decrease in the order of OUY-2 > OUK-2 > OUJ-2. Consequently, this work reveals that for the (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 the bathochromic shifts of λmax,abs and λmax,fl and the lowering of the LUMO energy level are dependent on the electron-withdrawing ability of the azine ring, which increases in the order of OUY-2 < OUK-2 < OUJ-2.

Theoretical study of charge-transport and optical properties of organic crystals: 4,5,9,10-pyrenediimides

This work presents a systematic study of the conducting and optical properties of a family of aromatic diimides reported recently and discusses the influences of side-chain substitution on the reorganization energies, crystal packing, electronic couplings and charge injection barrier of 4,5,9,10-pyrenediimide (PyDI). Quantum-chemical calculations combined with the Marcus–Hush electron transfer theory revealed that the introduction of a side chain into 4,5,9,10-pyrenediimide increases intermolecular steric interactions and hinders close intermolecular π–π stacking, which results in weak electronic couplings and finally causes lower intrinsic hole and electron mobility in t-C5-PyDI (μh = 0.004 cm2 V−1 s−1 and μe = 0.00003 cm2 V−1 s−1) than in the C5-PyDI crystal (μh = 0.16 cm2 V−1 s−1 and μe = 0.08 cm2 V−1 s−1). Furthermore, electronic spectra of C5-PyDI were simulated and time-dependent density functional theory calculation results showed that the predicted fluorescence maximum of t-C5-PyDI, corresponding to an S 1→S 0 transition process, is located at 485 nm, which is close to the experimental value (480 nm).