Red Radiation Research Articles

Structurally similar porphyrins and porphyrazines perform differently under green or red light irradiation against non-melanoma skin tumor cells

A porphyrin (H2P) and a porphyrazine (H2Pz) and their respective zinc complexes (ZnP and ZnPz), with the substituent N-ethylpyridyl-3-yl, were synthesized and their photophysical and phototoxic properties were compared. These substances showed high solubility in water due to the cationic moieties and without notable aggregation in this solvent. Photophysical studies showed that H2P and H2Pz have fluorescence quantum yields (ΦF) of 2.04% and 0.48% in water, respectively, that, upon metalation, decreases to 1.4% for the metalloporphyrin (ZnP) and increases to 6.1% for the metalloporphyrazine (ZnPz). Regarding the singlet oxygen production efficiency (ΦΔ) of the substances in water, a considerable increase from 16.2% to 41% was obtained for the porphyrin upon coordination to zinc, while the porphyrazines practically do not produce singlet oxygen (< 1%) in this solvent. When tested against human squamous cell carcinoma cells (A-431) and immortalized human keratinocytes (HaCaT), the toxicity of all compounds increased using green (520 ± 5 nm) and red (625 ± 5 nm) radiation when compared to the non-irradiated cells, however, phototoxicity was higher for the porphyrins using green light, while the porphyrazines performed better under red radiation. Furthermore, porphyrins had a higher phototoxic index than porphyrazines and greater selectivity for A-431 cancer cells compared to HaCaT cells. To the best of our knowledge, this is the first work that compares the photophysical response and in vitro anticancer activity of porphyrins and porphyrazines with the same substituent.

Investigating high-frequency quasi-periodic oscillations in the 6374 Å red coronal line observed during the total solar eclipse on August 21, 2017

Context. We present the results of the search for high-frequency quasi-periodic oscillations (HFQPOs) in the 6374-Å red line emission from the solar corona during the 2017 total solar eclipse (TSE). Aims. The existence of HFQPOs of coronal intensity remains unclear. Motivated by previous observations, this paper focuses on searching for the HFQPOs (&gt; 0.1 Hz) during the 2017 TSE. Methods. Wavelet analysis tools were used to analyze the radiation intensity oscillations in different height layers, local regions of interest (such as the east coronal loop, west cavity, etc.), and coronal feature points as well as changes in oscillations along coronal feature structures and the kinematic wobble of the coronal magnetic features. Results. We have observed oscillatory signals at multiple spatial locations, which reveal the existence of quasi-periodic slow magnetoacoustic waves. These signals display periods ranging from approximately 3 to 9 seconds, with a notable focus on periods around 4 seconds. Conclusions. High-frequency quasi-periodic slow magnetoacoustic oscillations (with periods less than 9.63 seconds) have been identified in the inner corona (at heights less than 1.4 R⊙) in the 6374 Å red coronal line radiation.

Ultraviolet-to-Blue Light Conversion Film Affects Both Leaf Photosynthetic Traits and Fruit Bioactive Compound Accumulation in Fragaria × ananassa

The influence of light downconversion films (red, pink and blue films) on leaf physiological features and fruit bioactive compound accumulation was studied in strawberry plants. Red, pink and blue films were able to convert light less utilised by plants into more efficient light wavebands with various possibilities depending on the film characteristics (blue film shifts UV into blue radiation; red film shifts green into red radiation, pink film shifts UV and green into blue and red radiation but to a lesser extent than red film). Indeed, by enhancing the quality of light available for photosynthesis, the utilization of these films holds the potential to improve agricultural productivity and sustainability. All of these light downconversion films resulted in higher plant fresh weight compared to a control colourless (Cnt) film, with plants grown under blue film (UV-to-blue light conversion) showing the most impressive results in terms of total leaf area (+25%), leaf thickness (+10%) and leaf mass per area (+15%). Simultaneously, during the flowering stage, plants under blue film had a higher net photosynthetic rate due to the increase in photosynthetically efficient wavelengths. Moreover, blue film resulted in the highest total phenolic (+40% and +28% than red and pink films, respectively) and flavonoid content (+54%, +84%, +70% than Cnt, red and pink films, respectively) in fruit, with specific effects on targeted phenols, i.e., quercetin, ellagic acid and its glycoside, ellagitannins, and procyanidins. In conclusion, the use of the UV-to-blue conversion light film tested herein represents an innovative solution to increase strawberry yield and promote fruit nutraceutical features, playing a pivotal role in ensuring food quality and security and sustainable agricultural practices.

Incandescent Lamp from Black Body Perspective

The incandescent lamp from black body perspective was investigated using commercial lamps of various watts. The major component of the incandescent lamp is the tungsten filament. The resistance of the tungsten filament was measured using a digital multimeter at an initial laboratory temperature. Light produced from lamp was separated into visible colours by an equilateral triangular glass prism. Deduced resistances were used to obtain equivalent temperatures by power-law parameterization. The Wien’s displacement law was used to estimate Peak wavelengths at different temperatures. The diameter of the tungsten was measured after dissecting the lamp, and this was used to determine its cross-sectional area. Both Wien’s displacement law and Stefan-Boltzmann expressions were applied in determining the filament’s spectral emissive power (SEP) in comparison with that of the visible spectrum. Planck’s graph of intensity using peak wavelength of tungsten filament as reference was juxtaposed with the intensity of visible spectrum using OriginPro 2016 SR0 b9.3.226. The maximum temperature attained was 2852.87 K with (SEP) of 1478955.24 Wm-2 for the 200W lamp. For the 100W lamp, the (SEP) obtained was 749347.9078 Wm-2 at 2489.14 K. Both temperatures, and even as low as 1250 K, were in agreement with Wien’s displacement law. The percentage estimation of visible spectrum in the radiation was about fourteen percent (14 %) while the rest was infra red radiation. This low visible light produced may be as a result of the non-ideal black body nature of the tungsten filament; and so, the incandescent lamp may be considered a quasi-black body.

Far-red radiation management for lettuce growth: Physiological and morphological features leading to energy optimization in vertical farming

Recently, far-red wavelengths (FR, 700–750 nm) have been largely investigated in indoor cultivation systems due to their morphological effects on plants (e.g., leaf expansion and stem elongation), resulting also in increasing yield. This work investigated the effect of substituting part of the red (R) and blue (B) radiation with far-red radiation, while keeping constant the photon flux density, in the light spectrum for lettuce grown in a vertical farm. Lettuce (Lactuca sativa var. Canasta) plants were transplanted and grown in an ebb-and-flow system for 29 days. During the cycle, plants were subjected to five different light treatments: a control treatment consisting of an optimized R and B spectrum (ratio of 3; RB3) with a photosynthetic photon flux density of 200 µmol m−2 s−1, and four treatments in which R and B were partially replaced by 10, 30, 50 and 70 µmol m−2 s−1 of FR light, resulting in an increasing FR fraction. Biomass production and most of the morphological parameters were affected from 15 days after transplanting (DAT), while stomatal conductance from 22 DAT. Leaf greenness and specific leaf area values were influenced by the FR radiation starting from 8 DAT. At 29 DAT, substitution of an amount of R and B photons equal to 30 (RB3–30) or 50 (RB3–50) µmol m−2 s−1 with the same amount of FR radiation resulted in increased leaf biomass in both fresh (+49 and +47%, respectively) and dry weight (+45 and +42%, respectively). With RB3–30, the increase was due to leaf area expansion (+103%), whereas stomatal conductance (gs) and quantum efficiency of photosystem II (ΦPSII) did not change compared with the spectrum with only R and B. With RB3–50, gs and ΦPSII decreased compared with RB3 (-27 and -6%, respectively), but the greater biomass accumulation was supported by the greater leaf expansion (+119 %). The adoption of RB3–30 and RB3–50 also promoted light use efficiency (+45 and +42 %, respectively), lighting energy use efficiency (+48 and +53 %, respectively) and therefore the overall energy performance of the system. The adoption of RB3–30 and RB3–50 is a valid strategy to increase yield for lettuce production, but further studies, also in relation to blue radiation intensity, are needed to avoid the negative effect on leaf pigmentation.

Halogenated BOIMPYs and Their Efficiency in Photodynamic Therapy

BOIMPY (bis‐ (borondifluoride)‐8‐imidazodipyrromethene) photosensitizers were developed for imaging‐guided photodynamic therapy (PDT). The introduction of heavy atoms (Br and I) to the b‐positions of BOIMPY combined with the twisted structure of the molecule was the strategy to enhance the intersystem crossing process of the BOIMPYs and reduce intermolecular π−π interactions of BOIMPY core. To clarify the electronic features of BOIMPY derivatives, their optical properties were studied using UV‐vis absorption, fluorescence spectroscopy, electrochemistry, and density functional theory (DFT) computing. The halogenated BOIMPYs exhibited a high absorption coefficient with high singlet oxygen generation ability (Φ∆ = 0.46 and 0.94 for brominated and iodinated BOIMPY, respectively). More significantly, an in vitro investigation showed that all derivatives displayed vivid fluorescence in cancer cells and that the halogenated BOIMPYs increased the effectiveness of tumor inhibition upon exposure to 660 nm red LED light radiation. The half‐maximal inhibitory concentrations for the iodinated and brominated BOIMPYs were 2.14 µM and 14.78 µM, respectively. Consequently, iodinated BOIMPY has been shown to represent a new class of photosensitizers with potential use in imaging‐guided photodynamic therapy.

Ca2LaTaO6:Bi3+/Mn4+ Phosphors with High Brightness Far-Red Emitting and Luminescence Enhancement for Plant Growth LED Lights and Temperature Sensor.

Herein, Bi3+/Mn4+ doped Ca2LaTaO6 phosphors with a double-perovskite structure were successfully synthesized with solid-state reaction at high temperature. The photoluminescence (PL) performances were investigated in detail. The blue radiation (∼465 nm) from the Bi3+ ion and the red radiation (∼686 nm) originating from the Mn4+ ion were obtained under 313 nm excitation. Especially, the pathway of energy transfer (Bi3+ → Mn4+) contributes to enhance the red emission intensity (Mn4+: ∼686 nm) in Ca2LaTaO6:Bi3+/Mn4+ system. The PL mechanism of Ca2LaTaO6:Bi3+/Mn4+ was analyzed through luminescence lifetimes and PL spectra. Moreover, the emitting bands of Ca2LaTaO6:Bi3+/Mn4+ were primarily matched with the absorbing bands of carotenoids and phytochrome PFR on behalf of plant growth, so the phosphors were suitable for the design of a plant growth light under near-ultraviolet to blue excitation. At last, the optical temperature dependent performances of the Ca2LaTaO6:Bi3+/Mn4+ were analyzed with luminescence intensity ratio technology. The sample has presented excellent temperature measuring relative sensitivity (SR = 2.106% K-1). The results illustrated that the Ca2LaTaO6:Bi3+/Mn4+ phosphor also can be used to develop an optical temperature sensor.

Compact source of energetic sub-nanosecond red pulses based on cascaded quasi-phase-matching in aperiodically poled lithium niobate.

We present a simple, compact source of sub-nanosecond pulsed red radiation, based on cascaded nonlinear optical processes-degenerate optical parametric generation and sum-frequency generation-performed with a sample of aperiodically poled lithium niobate pumped by passively Q-switched 1.064µm Nd:YAG laser. This system does not require feedback from an optical cavity; a single pass of the short pump is all that is required to obtain the cascaded processes, which shortens the output pulse. When pumped with a 1.2ns, 75µJ pulse, we obtain 670ps pulses centered around 709nm with an energy of 2.8µJ, corresponding to a peak power of over 4kW. A numerical model that predicts qualitatively the main characteristics of this source is also presented.

Effects of light qualities on growth and physiological-biochemical traits of Scutellaria baicalensis.

Canopy spectral composition significantly affects growth and functional traits of understory plants. In this study, we explored the optimal light condition suitable for enhancing Scutellaria baicalensis's yield and quality, aiming to provide scientific reference for the exploitation and utilization of medicinal plant resources in the understory of forests. We measured the responses of growth, morphology, biomass allocation, physiological traits, and secon-dary metabolites of S. baicalensis to different light qualities. S. baicalensis was cultured under five LED-light treatments including full spectrum light (control), ultraviolet-A (UV-A) radiation, blue, green, and red light. Results showed that UV-A significantly reduced plant height, base diameter, leaf thickness, leaf area ratio, and biomass of each organ. Red light significantly reduced base diameter, biomass, effective quantum yield of photosystem Ⅱ (ФPSⅡ), and total flavonoid concentration. Under blue light, root length and total biomass of S. baicalensis significantly increased by 48.0% and 10.8%, respectively, while leaf number and chlorophyll content significantly decreased by 20.0% and 31.6%, respectively. The other physiological and biochemical traits were consistent with their responses in control. Our results suggested that blue light promoted photosynthesis, biomass accumulation, and secondary metabolite synthesis of S. baicalensis, while red light and UV-A radiation negatively affected physiological and biochemical metabolic processes. Therefore, the ratio of blue light could be appropriately increased to improve the yield and quality of S. baicalensis.

Expression of cell cycle genes among the residents of settlements along the Techa River exposed to ionizing radiation &lt;i&gt;in utero&lt;/i&gt;

BACKGROUND: The period of intrauterine development is highly susceptible to the effects of ionizing radiation. While the consequences of radiation exposure during pregnancy are not yet fully understood, it is believed that individuals exposed to ionizing radiation in utero are at a greater risk of long-term health consequences.&#x0D; AIM: To analyze the expression of mRNA of cell cycle genes (TP53, MDM2, CDKN1A, ATM) in individuals exposed during intrauterine development to chronic radiation exposure after the Techa River accident.&#x0D; MATERIAL AND METHODS: The study was conducted over 60–70 years after the onset of chronic radiation exposure in a group of 170 individuals. Among them, 54 individuals were exposed to radiation during both prenatal and postnatal periods of development, while 80 individuals were exposed to chronic radiation after birth. The comparison group consisted of 36 individuals living in similar socio-economic conditions, with a lifetime cumulative dose of red bone marrow radiation not exceeding 70 mGy.&#x0D; RESULTS: Individuals residing in coastal villages along the Techa River, who were exposed to radiation during both the prenatal and postnatal stages of development, experience a reduction in the relative mRNA content of the MDM2 and CDKN1A genes compared to the control group and individuals who were exposed to chronic radiation after birth. The results of the correlation analysis indicate that there is no association between changes in mRNA expression of the studied genes and the accumulated absorbed dose of intrauterine and postnatal exposure of red bone marrow.&#x0D; CONCLUSION: The reduced transcriptional activity of the MDM2 and CDKN1A genes in individuals exposed to chronic radiation in utero may play a role in the development of long-term effects of radiation exposure in humans.

THE NDVI INDEX CHANGE OF THE CARPATHIAN REGION OF UKRAINE DURING 2000-2022

Systematic monitoring of the Carpathian region is necessary to preserve its unique natural resource potential. The NDVI index, or - Normalized Differential Vegetation Index, - is a convenient and informative indicator of the state of the vegetation cover, and is calculated on the basis of satellite data on the absorption and reflection of red and near-infrared radiation by the studied surface.&#x0D; To study the dynamics of vegetation index values and the state of the vegetation cover of the Carpathian region, images from the space projects Landsat 7 and 8 for the years 2000, 2013, 2020, 2021 and 2022 were downloaded and processed. The best indicator for analyzing changes in the state of vegetation cover in space and time is the integral index NDVImean. For 12 out of 15 processed images, the highest value of the integral index NDVImean=0.40-0.42 was found for polygon 1, which covers part of the Transcarpathian region. The lowest values of 0.13-0.16 were found for polygon 3, which covers parts of the Lviv, Ivano-Frankivsk, and Ternopil regions. The values of the areas covered with healthy or dense vegetation, for which NDVI˃0.33, were calculated. The maximum value of this indicator was 81.54% for polygon 1 in 2021, and the minimum was - 52.89% - for the polygon 3 in 2013.&#x0D; Keywords: Carpathian region; vegetation cover; vegetation index; multispectral analysis; raster; extent.

Mechanism of influence of water mist in a closed vessel on the explosion overpressure and flame propagation characteristics of magnesium dust

The primary purpose of this paper is to deeply investigate the impact of water mist on the explosive characteristics of magnesium dust and to broaden the inerting and suppression strategies for magnesium dust explosions. The explosion characteristics and flame propagation behaviors of magnesium dust/water mist mixtures were examined in a 16.2-L visualized closed vessel. The explosion products were further analyzed using SEM and XRD. The results indicate that with the addition of water mist, the explosivity of low-concentration magnesium dust (≤600 g/m3) increases. The explosive strength of three higher concentrations of magnesium dust (800 g/m3, 1200 g/m3, 1600 g/m3) notably decreases, with the Pmax dropping by 69.86%, 54.08%, and 46.22% respectively compared to pure magnesium dust. The leading edge of the preheat zone exhibits red radiation, the fluctuation range of the instantaneous flame propagation speed decreases, and cubic particles appear in the explosion products. These changes are mainly attributed to the hydrogen produced in the explosion of the magnesium dust/water mist mixture. Under the combined effects of hydrogen and steam, the preheat zone significantly expands. Moreover, as the concentration of hydrogen increases, its presence weakens the suppressing effect of the water mist, manifested by the evident slowing of the average flame speed, the maximum flame speed, and the rate of decrease in explosive strength. The suppression of magnesium dust explosions by water mist mainly relies on physical actions such as heat absorption, blocking thermal radiation, and diluting oxidizer concentration.

Impact of pre-sowing red laser irradiation of corn seeds on quality and quantity of harvest yield

As the population increases, more people need to be fed. In order to find a physical method that influence the corn production, this work is dedicated to evaluating the impact of pre-sowing red laser irradiation of corn (Zea mays L.) seeds on harvest yield. The aim was to analyze the influence of red laser radiation on corn seeds, on the quantity and quality of yield, on large-scale and open field production. It is hypothesized that at least one red laser irradiation treatment could improve corn crop yield. In radiation, a red laser diode at 660 nm with a power of 100 mW was used, two radiation densities were used (D1: 2 mW cm-2 and D2: 4 mW cm-2), applied during 4 exposure times (T1: 15, T2: 30, T3: 60 and T4: 120 s) and a control group without treatment (C). A random arrangement was used, in a 2 x 4 factorial scheme, totaling 8 treatments and control, with four replications. The data were subjected to an ANOVA and the means were compared with the Tukey test (HSD; p ≤ 0.05). The D2-T4 treatment produced the most significant impact concerning the control, improving yield by 19±1% (3 t ha-1), cob length 18±1%, cob diameter 22±3%, weight (16±2%) and corn kernels size (14±2%). We also find negative effects on yield, D2-T1 decreased crop yield around 16±1% (2.24 t ha-1). The results show a way to include this technique as a technique that can to increase or decrease corn yield. Keywords: Cob length; Maize; open field; Thousand kernel weight.

Allelopathy of Ricinus communis and light spectrum variation decrease emergence and growth of Cyperus rotundus

Weeds negatively influence agricultural production. However, those losses depend on weed specie, its time of emergence, and period of interference on agricultural crops. Synthetic herbicides are commonly used to control these plants species; however, they may cause damage to the environment, human beings and animals health, and this problem justify the need to develop alternative bioherbicides. To evaluate the allelopathic potential of Ricinus communis (Castor bean) and light spectrum variation on the emergence and growth of Cyperus rotundus L., a trial was carried out in a protected environment with 15% of brightness reduction at the Center for Agricultural and Environmental Sciences at the Paraíba State University. Four aqueous extract concentrations of R. communis leaves were tested (0, 5, 10, and 15%) and four light spectrums variations (white, purple, blue, and red lights). Variables such as emergence, length, dry matter accumulation and growth rates of shoots and root of C. rotundus seedlings were assessed. Data were analyzed by normality test, analysis of variance, polynomial regression, and averages test. Soot and root emergence, length, and dry matter accumulation of C. rotundus seedlings were reduced due to the allelopathy caused by R. communis aqueous extract leaves (15% concentration) and under purple or red light spectrum radiation.

Supplemental Lighting Quality Influences Time to Flower and Finished Quality of Three Long-Day Specialty Cut Flowers

Year-round demand for locally sourced specialty cut flowers continues to increase. However, due to low radiation intensities and temperatures, growers in northern latitudes must utilize greenhouses, but limited production information detailing manipulation of the radiation environment exists. Therefore, our objective is to quantify the influence of supplemental lighting (SL) quality on time to flower and harvest and stem quality of three long-day specialty cut flowers. Godetia ‘Grace Rose Pink’ (Clarkia amoena), snapdragon ‘Potomac Royal’ (Antirrhinum majus), and stock ‘Iron Rose’ (Matthiola incana) plugs are transplanted into bulb crates and placed in one of six greenhouse compartments with SL providing a total photon flux density of 120 µmol·m−2·s−1 from 0700 to 1900 HR. After four weeks, SL is extended to provide a 16 h photoperiod to induce flowering. SL treatments are provided by either high-pressure sodium (HPS) fixtures or various light-emitting diode (LED) fixtures. Treatments are defined by their 100 nm wavebands of blue (B; 400–500 nm), green (G; 500–600 nm), red (R; 600–700 nm), and far-red (FR; 700–800 nm) radiation (photon flux density in μmol·m−2·s−1) as B7G60R44FR9 (HPS120), B20G50R45FR5, B20R85FR15, B30G25R65, B120, or R120. Time to harvest (TTH) is up to 14, 15, and 10 d slower under R120 SL for godetia, snapdragon, and stock, respectively, compared to the quickest treatments (HPS120, B120, and B20R85FR15 SL). However, R120 SL produces cut flowers up to 18% longer than those grown under the quickest treatments. Both broad-spectrum LED fixtures slightly delay TTH compared to the quickest treatments. Stem caliper is not commercially different between treatments for godetia or snapdragon, although stems are up to 14% thinner for stock grown under B120 SL compared to the other treatments. Flower petal color is not commercially different between SL treatments. We recommend utilizing a SL fixture providing a spectrum similar to B20R85FR15 SL or B20G50R45FR5, as they elicit desirable crop responses with minimal developmental, quality, and visibility tradeoffs. While HPS lamps perform similarly to the recommended fixtures, we recommend utilizing LEDs for their higher photon efficacy and potential energy savings.

Роль спектральных характеристик источников излучения в формировании урожая салата при выращивании методом гидропоники

Growing plants indoors in the controlled environment involves the use of LED systems with an adjustable spectrum and intensity with manual or remote control. The aim of the study was to determine the role of different LED emission spectra in growth, development, and yield of lettuce cultivated hydroponically to develop requirements for the LED irradiator design. Studies were carried out in a growth chamber with periodic flooding hydroponics when irradiating lettuce plants of Kuk, Afitsion, and Khrizolit varieties under multispectral irradiators. The first irradiator has a radiation spectrum coinciding with the spectral distribution function of relative photosynthetic activity of solar radiation (control). The radiation of the second one coincides with the function of the spectral sensitivity of plants according to K.J. McCree. The third irradiator has an adjustable spectrum by three control channels for three parts of the spectrum coinciding with chlorophyll synthesis functions. It was found that the response of different lettuce varieties to the spectral composition of irradiation is specific. The maximum yield of the Kuk variety (4.45 kg/m2 ) was obtained under the first irradiator, that of lettuce Afitsion (4.7 kg/m2 ) and Khrizolit (6.55 kg/m2 ) - under the second one. Based on the results obtained the authors made requirements and designed an LED irradiator, which combines all the advantages of LED and digital technologies and provides for the implementation of the required radiation functions for laboratory research and in-vitro plant cultivation. It is noted that the LED module of the irradiator should include LEDs of violet, blue, red, dark red, and far red radiation, as well as LEDs of warm and cool white light colours.

Enhanced bright green luminescence from GdOF:Ho3+ up-conversion phosphor via Yb3+ doping

In this paper, a series of GdOF-based green phosphors doped with Ho3+ and Yb3+ ions was prepared by a simple co-precipitation method. The crystal structures and optical properties were investigated in detail. The intensity of the emission of GdOF:Yb3+,Ho3+ phosphors is enhanced by the effective energy transfer from Yb3+ to Ho3+, and the optimal luminescence is achieved with the Ho3+ doping amount of 0.1 mol% as well as Yb3+ doping amount of 5 mol%. Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho3+ or Yb3+. The purity of the green UC emission is further improved by enhancing the excitation pumping power. In addition, logarithmic functions of green, red and near-infrared radiation intensities were calculated versus logarithmic function of pump power for further study. A possible UC luminescence mechanism between Yb3+ and Ho3+ is discussed based on power-dependent UC luminescence spectrum and decay lifetimes. These results suggest that GdOF:Yb3+,Ho3+ phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging, display and illumination.

Structural, Optical, and Electrical Characterization of Biological and Bioactive Propolis Films.

Natural substances are potential compounds for green electronic devices. So, scientists have to explore and optimize their properties to insert them as active layers in electronic heterostructures. In this study, microstructural, optical, and electrical properties of thin layers of the propolis are investigated. Propolis is a biological organic bioactive material produced by honeybees. A stable, bioactive, green, and low-cost thin layer of this biocompatible material was deposited on different substrates using a propolis alcohol solution. The morphological studies show that the propolis thin film is dense and well covers the substrate surfaces. Transmittance spectra show that propolis film cuts off blue and ultraviolet (UV) radiation, which are responsible for food oxidation, nutrient losses, flavor degradation, and discoloration. Therefore, to prevent food deterioration, a propolis film can be used in food packaging. For red and near-infrared radiation (∼600-2700 nm), a propolis film is transparent. Between near-infrared and mid-infrared radiation (∼2700-3200 nm), a propolis film reveals significant photosensitivity and so can be used as a photosensor. The propolis film reveals an energy gap of 2.88 eV at room temperature, which enables potential optoelectronic applications in the UV and blue ranges. The electrical study shows that the propolis layer has semiconductor behavior and can be a potential active layer in biocompatible temperature sensors. In addition to its medical, pharmaceutical, and food industry applications, in light of this study, propolis presents amazing optical and electrical properties and is a promising candidate for food packaging, optoelectronics, transparent electronics, and bioelectronics.

Evaluation of the Effectiveness of Different LED Irradiators When Growing Red Mustard (Brassica juncea L.) in Indoor Farming

Investigation is devoted to the optimization of light spectrum and intensity used for red mustard growing. Notably, most of the studies devoted to red mustard growing were conducted on micro-greens, which is not enough for the development of methods and recommendations for making the right choices about the irradiation parameters for full-cycle cultivation. In this study, we tested four models of LED with different ratios of blue, green red and far red radiation intensity: 12:20:63:5; 15:30:49:6; 30:1:68:1, in two values of photon flux density (PFD)—120 and 180 µmol m−2 s−1—to determine the most effective combination for red mustard growing. The study was conducted in a container-type climate chamber, where the red leaf mustard was cultivated in hydroponics. On the 30th day of cultivation, the plant’s morphological, biochemical and chlorophyll fluorescence parameters, and reflection coefficients were recorded. The results indicated that the PFD 120 µmol m−2 s−1 had a worse effect on both mustard leaf biomass accumulation and nitrate concentration (13–30% higher) in the plants. The best lighting option for growing red mustard was the blue–red spectrum, as the most efficient in terms of converting electricity into biomass (77 Wth/g). This light spectrum contributes to plant development with a larger leaf area (60%) and a fresh mass (54%) compared with the control, which has a maximum similarity in spectrum percentage to the sunlight spectrum. The presence of green and far red radiation with the blue–red light spectrum in various proportions at the same level of PFD had a negative effect on plant fresh mass, leaf surface area and photosynthetic activity. The obtained results could be useful for lighting parameters’ optimization when growing red mustard in urban farms.

Influence of pre-sowing red laser irradiation of tomato seeds on the initial plant development, salinity stress tolerance, and harvest yield

This work discusses the laser irradiation effects on tomato seeds (Solanum lycopersicum L), regarding the initial plant development, salinity stress tolerance and harvest yield. The aim of this study was to find an optimal pre-sowing laser irradiation treatment to enhance tomato crop.A diode laser with wavelength of 660 nm and power 100 mW was used, 16 treatments were tested by 4 power densities (0.2, 0.4, 2 and 4 mW cm-2) applied during 4 exposure times (15, 30, 60, 120 s) and a control group without treatment. The study was divided into three stages,firstly it was selected an optimal laser treatment (04 mW cm-2, 30 s), in the second stage the optimal laser treatment was evaluated under salinity stress, and finally in the third stage the optimal laser treatment was evaluated on harvest yield. The optimal laser treatment, on the initial plant development enhanced germination by 10%, radicle growth by 19%, and hypocotyl growth by 13%, in comparison to the control. On seedlings under salinity stress, optimal laser treatment promote germination up to 20%, radicle growth up to 23%, and hypocotyl growth up to 12%.According to this study, saline stress inhibits PSII activity in tomato seedlings,whereas optimal laser treatment increased PSII activity around 71%. About greenhouse crop, optimal laser treatment improved mass produced by 26%. The present study shows a path for application ofpre-sowing red laser radiation treatments in tomato seeds to improve development, saline stress tolerance and final production of tomato crop.